CN105934335B - Multilayer film and its manufacturing method - Google Patents

Abstract

An object of the present invention is to provide a multilayer film comprising a base film and a particle-containing resin layer provided on the base film, wherein the resin layer is on a side opposite to the base film. The surface has a plurality of protrusions, and among the protrusions, (a) the number of protrusions with a height of 5 nm per 1 mm ² is set as N _A /mm ² , and (b) the number of protrusions with a height of 10 nm per 1 mm ² Let N _B pieces/mm ² , (c) the number of protrusions with a height of 15 nm per 1 mm ² be NC pieces/mm ² , and (d) the number of protrusions with a height of 20 nm per 1 mm ² be set as _{N D} (e) The number of protrusions with a height of 25 nm per 1 mm ² is set as NE /mm ² , ( _f ) The number of protrusions with a height of 30 nm per ¹ mm ² is set as NF _/ mm ² When , the value G expressed by _G =NA /NF is _3.5≤G≤7 , and NB _≥NC ≥N _{D ≥NE ≥NF .}

Description

Multilayer film and method of making the same

technical field

The present invention relates to multilayer films and methods for their manufacture.

Background technique

A multilayer film including a plurality of layers is known in the prior art (refer to Patent Documents 1 and 2). Such a multilayer film can realize various functions obtained by combining the properties of each layer, and thus has been used in a wide range of applications. For example, multilayer films are sometimes used in optical films used in various image display devices such as liquid crystal display devices, organic EL display devices, and plasma displays.

From the viewpoint of improving the production efficiency, the multilayer film as described above is often produced in the form of a long film. In addition, such a long multilayer film is generally wound up into a film roll, and is stored and conveyed in the state of the film roll.

Further, techniques such as Patent Document 3 are also known.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2000-79664

Patent Document 2: Japanese Patent Laid-Open No. 2010-264643

Patent Document 3: Japanese Patent Laid-Open No. 8-73623

SUMMARY OF THE INVENTION

Invention to solve problem

In a film roll manufactured by winding up a long multilayer film, a convex defect called a "bump" and having a width of about 1 mm to 3 mm may occur. If the above-described convex defects are transferred to the multilayer film, the multilayer film may be deformed at the transferred portion, and the optical properties of the portion may be impaired.

Furthermore, since the defect occurs not before winding the multilayer film, but after the roll is produced, it is difficult to detect by inspection on the production line of the multilayer film.

Furthermore, in order to detect the above-mentioned defects after the production of the film roll, the multilayer film needs to be successively fed out from the film roll to be inspected. Therefore, it takes time and labor to rewind the successively fed multilayer film. Therefore, it is difficult to screen out the film roll that does not have the above-mentioned defects while maintaining the state of the film roll.

In view of such a background, the development of a multilayer film capable of suppressing the occurrence of the above-mentioned defects in the case of a film roll has been demanded.

In addition, in optical films such as retardation films, it is generally required that the internal haze be small. The requirement for such a small internal haze is also the same when the optical film is a multilayer film. Therefore, in the multilayer film which can suppress the generation|occurrence|production of convex-shaped defect when it is made into a film roll as mentioned above, it is also requested|required that the internal haze can be reduced.

The present invention was made in view of the above problems, and an object of the present invention is to provide a multilayer film capable of suppressing the occurrence of the above-mentioned convex defects and reducing internal haze, and a method for producing the same when the film is wound up to form a film roll.

way of solving the problem

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, found that in a multilayer film including a base film and a resin layer containing particles, the surface of the resin layer on the opposite side to the base film has a predetermined regularity. The multilayered film of protrusions having different heights can suppress the occurrence of convex defects when the multilayered film is made into a film roll, and can reduce the internal haze of the multilayered film. Thus, the present invention has been completed.

That is, the present invention is as follows.

[1] A multilayer film comprising a base film and a particle-containing resin layer provided on the base film; wherein the surface of the resin layer opposite to the base film has a plurality of protrusions , among the protrusions (a) the number of protrusions with a height of 5 nm per 1 mm ² is set as N _A /mm ² , and (b) the number of protrusions with a height of 10 nm per 1 mm ² is set as N _B /mm ² , (c) the number of protrusions with a height of 15 nm per 1 mm ² is set to _NC /mm ² , (d) the number of protrusions with a height of 20 nm per 1 mm ² is set to _ND /mm ² , (e) When the number of protrusions with a height of 25 nm per 1 mm ² is set as NE/mm ² , and ( _f ) the number of protrusions with a height of 30 nm per 1 mm ² is set as NF _/ mm ² , G= The value G represented by N _A /NF is 3.5≤G≤7, and N _B ≥N _C ≥N _D ≥N _E ≥N _{F .}

[2] The multilayer film according to [1], wherein the resin layer contains a polymer, and the polymer contains a polyurethane.

[3] The multilayer film according to [1] or [2], wherein the particles include plural kinds of particles having different average particle diameters.

[4] The multilayer film according to [3], wherein the particles include particles (S) having an average particle diameter of less than 150 nm and particles (L) having an average particle diameter of 150 nm or more.

[5] The multilayer film according to [1], wherein the resin layer contains a polymer, and the particles contain particles (S) having an average particle diameter of less than 150 nm and particles having an average particle diameter of 150 nm or more Particles (L), the amount of the particles (S) in the resin layer is 2 parts by weight or more and 24 parts by weight or less with respect to 100 parts by weight of the polymer.

[6] The multilayer film according to [1], wherein the resin layer contains a polymer, and the particles contain particles (S) having an average particle diameter of less than 150 nm and particles having an average particle diameter of 150 nm or more Particles (L), the amount of the particles (L) in the resin layer is 5 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the polymer.

[7] The multilayer film according to any one of [1] to [6], wherein the particles are silica.

[8] The multilayer film according to any one of [1] to [7], wherein the resin layer has a thickness of 10 nm or more and 100 nm or less.

[9] The multilayer film according to any one of [1] to [8], wherein the multilayer film is a retardation film.

[10] The multilayer film according to any one of [1] to [8], wherein the multilayer film is a polarizer protective film.

[11] A method for producing a multilayer film, which is the method for producing a multilayer film according to any one of [1] to [10], wherein the method includes:

The process of mixing a polymer and a plurality of particles with different average particle diameters to obtain a fluid resin;

a step of applying the resin in a fluid state on a base film to form a film of the resin; and

A step of curing and/or drying the resin film formed on the base film to obtain a resin layer.

[12] The method for producing a multilayer film according to [11], wherein the particles include particles (S) having an average particle diameter of less than 150 nm and particles (L) having an average particle diameter of 150 nm or more.

effect of invention

When the multilayer film of the present invention is wound up to form a film roll, the occurrence of convex defects can be suppressed, and the internal haze can be reduced.

According to the manufacturing method of the multilayer film of this invention, when it winds up to make a film roll, the generation|occurence|production of a convex defect can be suppressed, and the multilayer film which can reduce internal haze can be manufactured.

Description of drawings

[ Fig. 1] Fig. 1 is a cross-sectional view schematically showing an example of a multilayer film according to an embodiment of the present invention.

[ Fig. 2] Fig. 2 is a front view schematically showing an example of a situation in which wrinkles are generated due to film adhesion in a conventional film roll.

[ Fig. 3] Fig. 3 is an example of a multilayer film that satisfies the conditions of _3.5≤G≤7 and N _B ≥N _C ≥N _D ≥N _E ≥NF The number of distribution plots on the vertical axis.

Symbol Description

100 Multilayer Films

110 substrate film

111 Surface of the base film opposite to the resin layer

120 resin layer

121 The surface opposite to the base film of the resin layer

122 Protrusions

200 film rolls

210 Wrinkles

220 take-up shaft

230 Sag

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the embodiments and examples, but the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily selected within the scope of the claims and equivalents of the present invention. change to be implemented.

In the following description, "(meth)acrylic acid" includes both acrylic acid and methacrylic acid. In addition, "(meth)acrylate" includes both acrylate and methacrylate.

In the following description, "(co)polymer" includes both polymers and copolymers.

In the following description, as long as the average particle diameter of the particles is not particularly limited, a particle size distribution is measured by a laser diffraction method, and the cumulative volume calculated from the small particle diameter side in the measured particle diameter distribution is 50%. particle size.

In the following description, the retardation in the in-plane direction of the film is a value represented by Re=(nx−ny)×d, unless otherwise specified. Further, the retardation Rth in the thickness direction of the film is a value represented by Rth={(nx+ny)/2-nz}×d. Here, nx represents the refractive index in the direction which gives the maximum refractive index among the directions (in-plane direction) perpendicular to the thickness direction of the film. ny represents the refractive index in the direction perpendicular to the direction of nx among the in-plane directions of the film. nz represents the refractive index in the thickness direction of the film. d represents the film thickness of the film. Unless otherwise specified, the measurement wavelength of the retardation is 550 nm. The retardation can be measured using a commercially available phase difference measuring apparatus (for example, "KOBRA-21ADH", manufactured by Oji Scientific Instruments Co., Ltd.) or the Senarmont method.

In addition, the "polarizer" includes not only a rigid member but also a flexible member such as a resin-made film.

[1. Overview of multilayer films]

FIG. 1 is a cross-sectional view schematically showing an example of a multilayer film 100 according to an embodiment of the present invention.

As shown in FIG. 1 , a multilayer film 100 according to an embodiment of the present invention includes a base film 110 and a resin layer 120 containing particles provided on the base film 110 . In addition, the resin layer 120 has a plurality of protrusions 122 on the surface 121 opposite to the base film 110 . In FIG. 1 , the symbol “T” represents the thickness of the resin layer 120 , and the symbol “H” represents the height of the protrusion 122 . As shown in FIG. 1 , the thickness T of the resin layer 120 represents the thickness of the region of the resin layer 120 where the protrusions 122 are not present.

In the multilayer film 100, the protrusions 122 on the surface 121 of the resin layer 120 satisfy: 3.5≤G≤7, and NB ≥N _C ≥N _D ≥N _{E ≥NF .}

Here, the value G is a value represented by G=N _A /NF _.

In addition, NA , _NB , _NC , _ND , _NE and _{NF represent} the following numbers.

( _a ) NA (unit: piece/mm ² ) represents the number of protrusions 122 with a height of 5 nm per 1 mm ² of protrusions 122 located on the surface 121 of the resin layer 120 opposite to the base film 110 .

( _b ) NB (unit: piece/mm ² ) represents the number of protrusions 122 with a height of 10 nm per 1 mm ² of protrusions 122 located on the surface 121 of the resin layer 120 opposite to the base film 110 .

(c) N _C (unit: piece/mm ² ) represents the number of protrusions 122 with a height of 15 nm per 1 mm ² of protrusions 122 located on the surface 121 of the resin layer 120 opposite to the base film 110 .

(d) N _D (unit: piece/mm ² ) represents the number of protrusions 122 with a height of 20 nm per 1 mm ² of protrusions 122 located on the surface 121 of the resin layer 120 opposite to the base film 110 .

( _e ) NE (unit: piece/mm ² ) represents the number of protrusions 122 with a height of 25 nm per 1 mm ² of protrusions 122 located on the surface 121 of the resin layer 120 opposite to the base film 110 .

( _f ) NF (unit: piece/mm ² ) represents the number of protrusions 122 with a height of 30 nm per 1 mm ² of protrusions 122 located on the surface 121 of the resin layer 120 opposite to the base film 110 .

Here, in the value of the protrusion height, when significant figures are considered, a height of 5 nm means 4.5 nm or more and 5.4 nm or less. In addition, similarly, considering significant figures, a height of 10 nm means 9.5 nm or more and 10.4 nm or less, a height of 15 nm means 14.5 nm or more and 15.4 nm or less, a height of 20 nm means 19.5 nm or more and 20.4 nm or less, and a height of 25 nm means 24.5 nm. 25.4 nm or more and 30 nm in height means 29.5 nm or more and 30.4 nm or less.

By having such a configuration, when the multilayer film 100 is wound up to form a film roll, the occurrence of convex defects can be suppressed, and the internal haze can be reduced.

(1) Regarding the suppression of the occurrence of convex defects:

The reason why the multilayer film of the present invention can suppress the occurrence of convex defects is not certain, but is presumed as follows according to the research of the present inventors. In addition, this invention is not limited to the estimation demonstrated below.

When a conventional film is wound up to manufacture a film roll, the rolled film may be partially stuck. The displacement of the film is restricted in the portion where the sticking occurs in this way. Therefore, during winding, the tension applied to the film cannot be dispersed in the entire film, and stress unevenness occurs in the film. Such uneven stress can sometimes lead to wrinkles on the film roll.

FIG. 2 is a front view schematically showing an example of a situation in which a wrinkle 210 is generated by the adhesion of the film in the conventional film roll 200 . As shown in FIG. 2, when the film roll 200 is manufactured by winding a film on the winding shaft 220, the wrinkles 210 are generally formed in a polygonal shape. Specifically, in many cases, a plurality of polygonal (generally rhombus) depressions 230 are formed in the axial and circumferential directions of the film roll 200 , and wrinkles 210 are formed at positions corresponding to polygonal sides of the depressions 230 .

Such wrinkles 210 do not substantially flex the membrane when they first occur. However, when the film roll is stored, the degree of depression (depth) of the polygonal depression 230 will gradually increase due to the self-weight of the film. Then, if the degree of depression of the depressions 230 increases, the degree of bending of the film increases in the portion where the wrinkles 210 are generated. It is considered that when the film is greatly bent beyond the elastic limit, the film is plastically deformed at the bent portion, resulting in a convex defect called a "bump".

On the other hand, as shown in FIG. 1 , the multilayer film 100 provided with the plurality of protrusions 122 satisfying the above conditions on the surface 121 opposite to the base film 110 of the resin layer 120 is excellent in the sliding properties of the surface 121 . It is presumed that the surface 121 of the resin layer 120 on the opposite side of the base film 110 is usually the outermost surface of the multilayer film 100 . Therefore, by making this surface 121 excellent in slidability, when the multilayer film 100 is wound up , the sticking of the rolled-up multilayer film 100 can be suppressed. Therefore, since the occurrence of wrinkles in the film roll can be suppressed, the occurrence of convex defects attributable to the wrinkles can be suppressed.

(2) Regarding the internal haze:

As a method of improving the slidability of the surface of the film as described above, it is conceivable to provide protrusions on the surface to increase the roughness of the surface, for example. However, when the protrusion height is high, the surface haze greatly increases due to optical effects such as reflection and refraction of the surface on which the protrusions are provided, and it is difficult to obtain an optical film. For this reason, the present inventors studied to provide low protrusions on the surface of the film to the extent that the surface haze can be kept small.

Further, the resin layer is formed as a resin layer containing particles. In general, in a resin layer containing particles, depending on the amount and size of the particles, the internal haze of the resin layer may increase significantly in some cases. Therefore, from the viewpoint of application to an optical film, it is preferable to design the resin layer so that the internal haze can be reduced. Generally, in order to avoid the increase of internal haze, it is preferable that the particle size is small. In addition, in order to prevent the increase of the internal haze and the occurrence of optical defects due to the mixing of large particles, it is preferable to use particles of the same size.

Therefore, the inventors of the present invention tried to provide a resin layer containing particles having a small size and uniform particle size on a base film, and to provide protrusions with a low height on the surface of the film. However, the slidability of the surface having the protrusions of the film thus obtained is small, and it is difficult to suppress the occurrence of convex defects in the film roll.

Therefore, the present inventors predicted that when the size of the particles is increased and the height of the protrusions is increased, the sliding properties of the surface on which the protrusions are provided will be improved. Then, the present inventors increased the protrusion height and the particle size, and conducted the same research as above. However, even if the protrusion height is increased, the slidability is not sufficiently improved, and it is difficult to suppress the occurrence of convex defects in the film roll.

In addition, it is considered that it is possible to increase the slidability of the surface having the protrusions by increasing the number of protrusions. However, in order to increase the number of protrusions, it is necessary to increase the number of particles. On the other hand, if the number of particles is too large, the internal haze may increase due to reflection and refraction inside the resin layer.

On the other hand, in the multilayer film 100 shown in FIG. 1 , the surface 121 of the resin layer 120 on the opposite side to the base film 110 is provided with a surface 121 that satisfies 3.5≦G≦7 and N _B ≧N _C ≧ _ND ≧ _{Protrusions 122} for the condition of NE ≥ NF. These conditions (3.5≤G≤7 and N _B ≥N _C ≥N _D ≥N _E ≥N _F ) relate to the low protrusions 122 to such an extent that the surface haze does not increase, indicating that the distribution of the heights of the protrusions 122 is wide, And the number of high protrusions is less than the number of low protrusions. As an example of the multilayer film 100 that satisfies this condition, FIG. 3 shows a distribution diagram with the height of the protrusions 122 as the horizontal axis and the number of the protrusions 122 as the vertical axis. These conditions indicate that, in a distribution diagram as shown in FIG. 3 with the height of the protrusions 122 on the horizontal axis and the number of the protrusions 122 on the vertical axis, the width of the peak is wide and gentle, and the apex of the peak is located in a desired small range. In this way, the surface 121 including the protrusions 122 having different heights has remarkably high sliding properties. Conventionally, it has not been considered that the slidability of the surface having the protrusions can be adjusted by adjusting the distribution of the protrusions for the low protrusions to the extent that the surface haze can be suppressed. From such a conventional knowledge, it can be said that the slidability of the surface having the protrusions is improved by adjusting the distribution of the height of the protrusions as described above, which is an unexpected effect.

In addition, the resin layer having protrusions satisfying the above-mentioned conditions (3.5≤G≤7 and N _B ≥ N _C ≥ N _D ≥ N _E ≥ N _F ) can be used by appropriately combining small-sized particles with large-sized particles. Thereby using a small amount of particles to manufacture. Since the amount of particles can be reduced, an increase in the internal haze caused by the resin layer can be avoided.

Therefore, the multilayer film of the present invention can suppress the occurrence of convex defects in the film roll without causing an increase in internal haze even when protrusions are formed by particles contained in the resin layer. Conventionally, from the viewpoint of not impairing the proper properties of the optical film, the smaller the size of the particles used in the optical film, the more preferable it is, and the more uniform the particle size is, the more preferable. From such a conventional understanding, it can be said that it is an unexpected effect to provide a resin layer with a small internal haze and excellent surface slidability by using a combination of small-sized particles and large-sized particles as described above.

[2. Substrate film]

As the base film, a resin-made film is usually used. As the resin constituting the base film, any polymer-containing resin can be used. Among them, as the resin constituting the base film, a thermoplastic resin is preferable, and an alicyclic olefin resin is particularly preferable. The alicyclic olefin resin is a resin containing an alicyclic olefin polymer, has excellent properties such as transparency, low moisture absorption, dimensional stability, and light weight, and is suitable for use in optical films.

In addition, the base film may be a film of a single-layer structure including only one layer, or may be a film of a multilayer structure including two or more layers. When the base film has a multilayer structure, it is preferable that one or more of the layers included in the base film are formed of an alicyclic olefin resin.

The alicyclic olefin polymer is a polymer having an alicyclic structure in the structural unit of the polymer, and any of a polymer having an alicyclic structure in the main chain and a polymer having an alicyclic structure in a side chain can be used polymer. Moreover, an alicyclic olefin polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Among them, from the viewpoints of mechanical strength, heat resistance, and the like, polymers having an alicyclic structure in the main chain are preferred.

As an alicyclic structure, a saturated alicyclic hydrocarbon (cycloalkane) structure, an unsaturated alicyclic hydrocarbon (cycloolefin, a cycloalkyne) structure, etc. are mentioned, for example. Among them, from the viewpoints of mechanical strength, heat resistance, and the like, a cycloalkane structure and a cycloolefin structure are preferable, and among them, a cycloalkane structure is particularly preferable.

In terms of the number of carbon atoms constituting the alicyclic structure, the number of carbon atoms per alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, especially The range of 15 or less is preferable. Thereby, the mechanical strength, heat resistance, and moldability of the base film can be highly balanced, which is preferable.

The ratio of the structural unit having an alicyclic structure in the alicyclic olefin polymer can be appropriately selected according to the purpose of use, but is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. If the ratio of the structural unit which has an alicyclic structure in an alicyclic olefin polymer exists in this range, it is preferable from a viewpoint of transparency and heat resistance of a base film.

Examples of alicyclic olefin polymers include norbornene polymers, monocyclic cyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrogenation thereof things etc. Among them, norbornene polymers are preferable because of their good transparency and moldability.

As the norbornene polymer, for example, a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and an arbitrary monomer, or a hydrogenated product thereof can be mentioned. ; an addition polymer of a monomer having a norbornene structure, or an addition copolymer of a monomer having a norbornene structure and any monomer, or their hydrogenated products. Among them, from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, light weight, and the like, hydrogenated products of ring-opening polymers of monomers having a norbornene structure, and hydrogenated polymers having reduced Hydrogenated products of ring-opening copolymers of bornene-structured monomers.

Examples of monomers having a norbornene structure include bicyclo[2.2.1]hept-2-ene (common name: norbornene), tricyclo[ ^4.3.0.12,5 ]dec-3,7 -diene (common name: dicyclopentadiene), 7,8-benzotricyclo[4.3.0.1 ^2,5 ]dec-3-ene (common name: epimethylenetetrahydrofluorene), tetracyclo[ 4.4.0.1 ^{2,5.1 7,10} ] Dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, derivatives having substituents on the ring), etc. . Here, as a substituent, an alkyl group, an alkylene group, a polar group, etc. are mentioned, for example. In addition, these substituents may be the same or different, and a plurality of them may be bonded to form a ring. Moreover, the monomer which has a norbornene structure may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

As a kind of polar group, a hetero atom, the atomic group which has a hetero atom, etc. are mentioned, for example. As a hetero atom, an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a halogen atom, etc. are mentioned, for example. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, a sulfonic acid group, and the like.

Examples of any monomers that can undergo ring-opening copolymerization with a monomer having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene, and derivatives thereof; Cyclic conjugated dienes such as alkene, cycloheptadiene, and derivatives thereof, etc. Any monomer which can undergo ring-opening copolymerization with a monomer having a norbornene structure may be used alone or in combination of two or more at any ratio.

A ring-opening polymer of a monomer having a norbornene structure, and a ring-opening copolymer of an arbitrary monomer copolymerizable with a monomer having a norbornene structure, for example, can be obtained by subjecting the monomer to a known ring-opening polymerization catalyst. It is produced by polymerization or copolymerization in the presence of .

Examples of arbitrary monomers that can be addition-copolymerized with monomers having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; Cycloalkenes such as cyclobutene, cyclopentene, cyclohexene and their derivatives; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4- Non-conjugated dienes such as hexadiene, etc. Among them, α-olefins are preferable, and ethylene is more preferable. Moreover, the arbitrary monomer which can be addition-copolymerized with the monomer which has a norbornene structure may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

An addition polymer of a monomer having a norbornene structure, and an addition copolymer of any monomer copolymerizable with a monomer having a norbornene structure, for example, can be obtained by subjecting the monomer to a known addition polymerization catalyst. It is produced by polymerization or copolymerization in the presence of .

Examples of the monocyclic cyclic olefin polymer include addition polymers of cyclic olefin monomers having a monocyclic ring, such as cyclohexene, cycloheptene, and cyclooctene.

Examples of the cyclic conjugated diene polymer include a cyclization reaction of an addition polymer of a conjugated diene monomer such as 1,3-butadiene, isoprene, and chloroprene. The obtained polymers; 1,2- or 1,4-addition polymers of cyclic conjugated diene monomers such as cyclopentadiene and cyclohexadiene; and their hydrogenated products.

Examples of vinyl alicyclic hydrocarbon polymers include polymers of vinyl alicyclic hydrocarbon monomers such as vinyl cyclohexene and vinyl cyclohexane, and their hydrogenated products; Hydrogenated product obtained by hydrogenating the aromatic ring part contained in a polymer obtained by polymerizing vinyl aromatic hydrocarbon monomers such as vinyl styrene; vinyl alicyclic hydrocarbon monomer, or vinyl aromatic hydrocarbon monomer Hydrogenated products of aromatic rings of copolymers such as random copolymers and block copolymers formed with arbitrary monomers copolymerizable with these vinyl aromatic hydrocarbon monomers, and the like. As said block copolymer, a diblock copolymer, a triblock copolymer, or a multiblock copolymer of the above, and a gradient block copolymer etc. are mentioned, for example.

The weight average molecular weight (Mw) of the polymer contained in the resin constituting the base film is usually 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, usually 100,000 or less, preferably 80,000 or less, and more preferably 50,000 or less . Here, the weight average molecular weight is the weight average molecular weight in terms of polyisoprene or polystyrene measured by gel permeation chromatography using cyclohexane as a solvent. In addition, when a sample is insoluble in cyclohexane, toluene can also be used as a solvent for gel permeation chromatography. When the weight average molecular weight is in such a range, the mechanical strength and moldability of the multilayer film can be highly balanced, which is preferable.

The molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the polymer contained in the resin constituting the base film is usually 1.2 or more, preferably 1.5 or more, more preferably 1.8 or more, and usually 3.5 or less , preferably 3.0 or less, more preferably 2.7 or less. By making molecular weight distribution more than the lower limit of the said range, productivity of a polymer can be improved, and cost can be suppressed. Moreover, since low molecular weight components can be reduced by being below the upper limit, relaxation time can be lengthened. Therefore, relaxation at the time of exposure to high temperature can be suppressed, and the stability of the base film can be improved.

The absolute value of the photoelastic coefficient C of the polymer contained in the resin constituting the base film is preferably 10×10 ^-12 Pa ^-1 or less, more preferably 7×10 ^-12 Pa ^-1 or less, and particularly preferably 4× 10 ^-12 Pa ^-1 or less. When the birefringence is Δn and the stress is σ, the photoelastic coefficient C is a value represented by “C=Δn/σ”. By making the photoelastic coefficient of the polymer into the above-mentioned range, the variation in retardation Re in the in-plane direction of the base film can be reduced.

The saturated water absorption of the polymer contained in the resin constituting the base film is preferably 0.03% by weight or less, more preferably 0.02% by weight or less, and particularly preferably 0.01% by weight or less. If the saturated water absorption is within the above-mentioned range, the time-dependent changes in the retardation in the in-plane direction and the retardation in the thickness direction of the base film can be reduced. In addition, the deterioration of the polarizing plate and the image display device including the multilayer film of the present invention can be suppressed, and the display of the display can be kept stable and good for a long period of time.

The saturated water absorption is a value expressed as a percentage of the mass increased after immersing a test piece in water at a constant temperature for a certain period of time with respect to the mass of the test piece before immersion. Usually, the test piece is immersed in water at 23° C. for 24 hours and measured. The saturated water absorption rate of the polymer can be adjusted to the above range, for example, by reducing the amount of polar groups in the polymer. Therefore, from the viewpoint of further reducing the saturated water absorption rate, the polymer contained in the resin constituting the base film preferably does not have a polar group.

As long as the effects of the present invention are not significantly impaired, the resin constituting the base film may contain arbitrary components other than the polymer. Examples of the optional components include colorants such as pigments and dyes; plasticizers; optical brighteners; dispersants; heat stabilizers; light stabilizers; ultraviolet absorbers; antistatic agents; antioxidants; lubricants additives; surfactants and other additives. These components may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

In addition, when an alicyclic olefin resin is used as resin which comprises a base film, it is preferable that this alicyclic olefin resin does not contain particle|grains substantially. Here, the term "substantially not containing particles" means that even if the resin contains particles, only the amount allowed to increase the haze of the base film is 0.05% or less relative to the state in which particles are not contained at all . The alicyclic olefin polymer tends to have insufficient affinity with many organic particles and inorganic particles. Therefore, when the alicyclic olefin resin containing particles is stretched, voids are likely to be generated. However, by reducing the amount of particles as described above, the generation of voids during stretching can be suppressed, thereby preventing an increase in haze.

The amounts of the polymer and additives contained in the resin constituting the base film can be arbitrarily set within a range in which the multilayer film of the present invention can express desired optical properties. For example, the ratio of the polymer in the resin constituting the base film is generally 50% to 100%, or 70% to 100%. In particular, when an alicyclic olefin resin is used as the resin constituting the base film, the ratio of the polymer contained in the alicyclic olefin resin is usually 80 to 100%, preferably 90 to 100%.

As described above, the base film may be a film of a single-layer structure including only one layer, or may be a film of a multilayer structure including two or more layers. By making the base film a film of a multilayer structure, the multilayer film of the present invention can be used as an optical film having various properties.

When the base film is provided with two or more layers, it may be provided with one type of two or more layers, or may be provided with two or more different layers. In addition, a layer formed of a resin other than the above-mentioned alicyclic olefin resin may be provided in the base film. As a layer which consists of resins other than alicyclic olefin resin, the layer which has functions, such as damage prevention, antireflection, antistatic, antiglare, and antifouling, is mentioned, for example.

The average thickness of the base film is preferably 5 μm or more, more preferably 20 μm or more, preferably 500 μm or less, and more preferably 300 μm or less.

Further, the thickness variation of the base film is preferably within ±3% of the above-mentioned average thickness in the longitudinal direction and the width direction. By changing the thickness to the above-mentioned range, variation in optical properties such as retardation of the base film can be reduced.

The amount of the volatile component contained in the base film is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and still more preferably 0.02% by weight or less. By making the quantity of a volatile component into the said range, dimensional stability can be improved, and the time-dependent change of the retardation in the in-plane direction of the base film and the retardation in the thickness direction can be reduced. Moreover, since the deterioration of the polarizing plate, the image display apparatus, etc. provided with the multilayer film of this invention can be suppressed, the display of a display can be kept stable and favorable for a long period of time. Here, the volatile component refers to a substance having a molecular weight of 200 or less. As a volatile component, a residual monomer, a solvent, etc. are mentioned, for example. The amount of volatile components can be quantified by analyzing by gas chromatography as the total amount of substances having a molecular weight of 200 or less.

There is no limitation on the manufacturing method of the base film. The base film can be obtained by molding the resin for forming the base film by any film forming method. As a film forming method, a casting method, an extrusion forming method, an inflation forming method, etc. are mentioned, for example. Among them, the melt extrusion method which does not use a solvent can effectively reduce the amount of residual volatile components, and is preferable from the viewpoint of the global environment, the operating environment, and the viewpoint of being excellent in production efficiency. As a melt extrusion method, the inflation method using a die etc. is mentioned, Of these, the method using a T-die is preferable from a viewpoint of being excellent in productivity and thickness accuracy.

In addition, when the base film is provided with two or more layers, there is no limitation on the manufacturing method of the base film. For example, a base film can be manufactured by laminating the separately manufactured film layers using an adhesive as needed. The adhesive agent can be appropriately selected according to the kind of resin which forms the film layer to be bonded. Examples of adhesives include acrylic adhesives, urethane adhesives, polyester adhesives, polyvinyl alcohol adhesives, polyolefin adhesives, and modified polyolefin adhesives , polyvinyl alkyl ether adhesive, rubber adhesive, ethylene-vinyl acetate adhesive, vinyl chloride-vinyl acetate adhesive, SEBS (styrene-ethylene-butylene-styrene copolymer) Adhesives, SIS (styrene-isoprene-styrene block copolymer) adhesives, vinyl adhesives such as ethylene-styrene copolymers, ethylene-methyl (meth)acrylate copolymers, ethylene -Acrylate adhesives such as ethyl (meth)acrylate copolymers, etc. An adhesive may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios. The average thickness of the adhesive layer formed from the adhesive is preferably 0.1 μm or more, more preferably 0.5 μm or more, preferably 10 μm or less, and more preferably 5 μm or less.

In the case of producing a base film having two or more layers without using an adhesive, for example, co-extrusion molding such as co-extrusion T-die method, co-extrusion inflation method, and co-extrusion lamination method can be used. method; dry lamination and other film lamination methods, etc.

In addition, a base film including two or more layers can also be produced by, for example, a coating molding method in which a solution containing a resin constituting another film layer is applied to the surface of a certain film layer.

Among them, the co-extrusion molding method is preferable from the viewpoint of production efficiency and from the viewpoint of not leaving volatile components such as solvents remaining in the base film. Among the co-extrusion molding methods, the co-extrusion T-die method is particularly preferable. Further, among the co-extrusion T-die method, the feed block method and the multi-manifold method are exemplified, and the multi-manifold method is more preferable from the viewpoint that the variation in thickness of each layer can be reduced.

The base film may be an unstretched film that has not been stretched, or a stretched film that has been stretched. In addition, when the base film is provided with two or more layers, a stretched film may be obtained by bonding the film layers that have been stretched in advance, or a multilayer structure obtained by co-extrusion or the like may be stretched. The front film is stretched to obtain a stretched film.

The stretching method is not particularly limited, and for example, any method of a uniaxial stretching method and a biaxial stretching method can be employed. As an example of the stretching method, examples of the uniaxial stretching method include: a method of uniaxially stretching in the longitudinal direction using the difference in the peripheral speed of the rolls for film transport; using a tenter stretching machine A method of uniaxial stretching in the width direction, etc. In addition, as an example of the biaxial stretching method, stretching in the longitudinal direction while increasing the interval between the jigs for fixing and stretching in the width direction according to the opening angle of the guide rails can be mentioned. Biaxial stretching method: After stretching in the longitudinal direction using the difference in the peripheral speed between the rolls for film conveying, the both ends of the film are clamped with clamps and stretched in the width direction using a tenter stretching machine. Biaxial stretching method, etc. Furthermore, for example, it is also possible to use a tenter stretching machine that can apply a conveying force, a stretching force, or a receiving force at different speeds on the left and right in the width direction or the longitudinal direction, and a tenter stretching machine that is neither parallel nor perpendicular to the width direction of the film can be used. A diagonal stretching method in which the direction is continuously stretched diagonally.

As an apparatus for stretching, a longitudinal uniaxial stretching machine, a tenter stretching machine, a foam stretching machine, a roll stretching machine, etc. are mentioned, for example. In terms of stretching temperature, when the glass transition temperature of the resin constituting the film to be stretched is Tg, the stretching temperature is preferably (Tg-30°C) or higher, more preferably (Tg-10°C) or higher, and preferably (Tg+60°C) or less, more preferably (Tg+50°C) or less. The draw ratio can be appropriately selected according to the optical properties of the base film to be used. A specific draw ratio is usually 1.05 times or more, preferably 1.1 times or more, usually 10.0 times or less, preferably 2.0 times or less.

[3. Resin layer]

The resin layer is a layer provided on the base film, and has protrusions on the surface opposite to the base film. The value G represented by G=N _{A /} NF of the protrusion is usually 3.5 or more, preferably 3.6 or more, preferably 4.0 or more, more preferably 4.5 or more, usually 7.0 or less, preferably 6.4 or less, more preferably 6.0 or less, more preferably 5.5 or less . A value G greater than 0 indicates that a region without low protrusions is not provided on the face 121 of the resin layer 120 such as shown in FIG. 1 . Further, if the value G is equal to or less than the upper limit of the above-mentioned range, it means that a local area with excessively low protrusions and an area with few high protrusions are not provided on the surface 121 of the resin layer 120 shown in FIG. 1 . Therefore, the value G being equal to or less than the upper limit of the above-mentioned range indicates that the low protrusion and the high protrusion are combined in a well-balanced manner. Further, that the value G is equal to or greater than the lower limit of the above-mentioned range indicates that the number of protrusions can be suppressed to an extent that does not cause an increase in the internal haze because the number of protrusions is appropriate. Therefore, by making the value G in the said range, when winding up and making a film roll, generation|occurrence|production of a convex defect can be suppressed, and internal haze can be reduced.

Further, the protrusions located on the surface opposite to the base film of the resin layer satisfy N _B ≧N _C ≧N _D ≧N _E ≧ _NF . This means that the number of protrusions with a low height is greater than the number of protrusions with a high height. By satisfying such conditions, it is possible to improve the slidability of the surface having the protrusions of the resin layer, and further, to reduce the internal haze of the resin layer.

The height and number of protrusions as described above can be controlled by, for example, adjusting the size of particles contained in the resin layer, the method of evaporation of the solvent during production of the resin layer, and the order of steps for forming the resin layer. The "solvent" in this specification includes not only a so-called solvent but also a dispersion medium.

The resin layer contains particles. In the resin layer, the particles have a function of forming protrusions on the surface of the resin layer opposite to the base film. Furthermore, the resin layer usually contains a polymer. Hereinafter, this polymer is also appropriately referred to as a "binding polymer". In the resin layer, the binding polymer has a function of keeping particles from being detached from the resin layer and a function of bonding the resin layer and the base film. The resin layer containing the particles and the binder polymer in this way can generally be produced by a production method including the steps of: mixing the particles and the binder polymer to obtain a fluid resin; A step of applying a fluid resin on a base film to form a resin film; and a step of curing and/or drying the resin film formed on the base film to obtain a resin layer. Hereinafter, the fluid-like resin used for the formation of the resin layer is also referred to as "coating resin". Hereinafter, this production method will be described.

As the binding polymer, a suitable polymer can be arbitrarily used according to the application of the multilayer film. Among them, the binder polymer preferably contains polyurethane from the viewpoint of being able to stably prevent convex defects when the multilayer film is made into a film roll.

As the polyurethane, for example, a polyurethane obtained by reacting (i) a component containing an average of two or more activated hydrogens in one molecule and (ii) a polyisocyanate component can be used.

Further, as the polyurethane, for example, a polyurethane produced by chain-extending an isocyanate group-containing prepolymer with a chain extender and adding water to form a dispersion can be used. The above-mentioned isocyanate group-containing prepolymer can be produced by subjecting the above-mentioned (i) component and the above-mentioned (ii) component to a urethanization reaction on the condition that the isocyanate group is excessive. The urethanization reaction can be carried out in an organic solvent that is inactive to the reaction and has a high affinity for water. Furthermore, the prepolymer containing isocyanate groups may be neutralized prior to chain extension of the prepolymer. As a chain extension method of the isocyanate group-containing prepolymer, a method of reacting an isocyanate group-containing prepolymer and a chain extender in the presence of a catalyst as necessary can be mentioned. In this case, as the chain extender, water, water-soluble polyamines, glycols, or the like can be used.

As said (i) component, the component which has a hydroxylic activated hydrogen is preferable, for example, the compound which has an average of 2 or more hydroxyl groups in 1 molecule is preferable. Specific examples of the component (i) include the following (1) polyol compounds, (2) polyether polyols, (3) polyester polyols, (4) polyether ester polyols, and (5) ) polycarbonate polyol.

(1) Polyol compound:

As the polyol compound, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-Butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl- 1,3-pentanediol, tricyclodecanedimethanol, 1,4-cyclohexanedimethanol, 2,2-dimethylpropanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, glycerol, trimethylolpropane, etc.

(2) Polyether polyol:

Examples of polyether polyols include the above-mentioned (1) alkylene oxide adducts of polyol compounds; ring-opening (co)polymers of alkylene oxides and cyclic ethers (for example, tetrahydrofuran, etc.); polyethylene glycol, poly Propylene glycol, ethylene glycol-propylene glycol copolymer, 1,4-butanediol copolymer; glycols such as ethylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and polyoctamethylene glycol class; etc. Specific examples of polyether polyols include poly(oxypropylene ether) polyols, poly(oxyethylene-trimethylene ether) polyols, and the like.

(3) Polyester polyol:

As a polyester polyol, the thing obtained by polycondensing polyvalent carboxylic acid or its acid anhydride, and the said (1) polyol compound under the condition that a hydroxyl group is excessive, etc. are mentioned, for example. Here, examples of polyvalent carboxylic acids include adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. Dicarboxylic acids such as formic acid; tricarboxylic acids such as trimellitic acid. Specific examples of polyester polyols include ethylene glycol-adipic acid condensate, butanediol-adipic acid condensate, hexamethylene glycol-adipic acid condensate, ethylene glycol- Propylene glycol-adipic acid condensate, or polylactone diol obtained by ring-opening polymerization of lactone using diol as an initiator, etc.

(4) Polyetherester polyol:

As the polyetherester polyol, for example, an ether group-containing polyol, or a mixture of the polyol and other diols, a polyvalent carboxylic acid exemplified in the above (3) or an acid anhydride thereof, and an oxidative mixture can be mentioned. Substances formed by the reaction of alkenes, etc. Here, as said ether group-containing polyol, the said (2) polyether polyol, diethylene glycol, etc. are mentioned, for example. As a specific example of a polyetherester polyol, a polytetramethylene glycol-adipic acid condensate etc. are mentioned.

(5) Polycarbonate polyol:

As a polycarbonate polyol, the compound etc. which are represented by general formula HO-R-(OC(O)-OR) _x -OH are mentioned, for example. Here, R in the above formula represents a saturated fatty acid polyol residue having 1 to 12 carbon atoms. In addition, x in the said formula represents the number of the structural unit of a molecule, and is an integer of 5-50 normally. These compounds can be obtained by a transesterification method in which a saturated aliphatic polyol and a substituted carbonate (for example, diethyl carbonate, diphenyl carbonate, etc.) are reacted with excess hydroxyl groups; A method of reacting a polyol and phosgene, or a method of further reacting with a saturated aliphatic polyol, if necessary, and the like.

The said (i) component may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

As (ii) component (that is, a polyisocyanate component) which reacts with said (i) component, the compound which contains an average of 2 or more isocyanate groups in 1 molecule is mentioned, for example. The compound may be an aliphatic compound, an alicyclic compound, or an aromatic compound.

The aliphatic polyisocyanate compound is preferably an aliphatic diisocyanate having 1 to 12 carbon atoms, and examples thereof include hexamethylene diisocyanate, 2,2,4-trimethylhexanediisocyanate, and hexanediisocyanate. (HDI) etc.

As the alicyclic polyisocyanate compound, an alicyclic diisocyanate having 4 to 18 carbon atoms is preferable, and examples thereof include 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and isophorone diisocyanate. Isocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), etc.

Examples of the aromatic polyisocyanate include toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and the like.

The said (ii) component may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The above-mentioned (i) component and (ii) component can be arbitrarily selected and used appropriately according to the application of the multilayer film. Among them, as the component (i), those having a bond that is not easily hydrolyzed are preferably used, (2) polyether polyol and (5) polycarbonate polyol are specifically preferred, and (2) polyether polyol is particularly preferred.

In addition, an acid structure may be contained in the molecular structure of these polyurethanes. Since the acid structure-containing polyurethane can be dispersed in water without using a surfactant or in a small amount of the surfactant, improvement in the water resistance of the resin layer can be expected. This polyurethane is called a self-emulsifying type, which means that the polyurethane particles can be stably dispersed in water only by molecular ionicity even in the absence of a surfactant. In addition, since the acid structure-containing polyurethane does not require a surfactant or only needs a small amount of the surfactant, it is excellent in adhesion to the base film and can maintain high transparency.

As an acid structure, acid groups, such as a carboxyl group (-COOH), a sulfo group ( _-SO3H ), etc. are mentioned, for example. In addition, in polyurethane, an acid structure may exist in a side chain, and may exist in a terminal. One type of acid structure may be used, or two or more types may be used in combination in any ratio.

The amount of the acid structure is preferably 20 mgKOH/g or more, more preferably 25 mgKOH/g or more, preferably 250 mgKOH/g or less, and more preferably 150 mgKOH/g or less, in terms of the acid value of the coating resin. By making the acid value more than the lower limit of the above-mentioned range, the water dispersibility of the polyurethane can be improved. Moreover, the water resistance of a resin layer can be made favorable by making an acid value less than an upper limit.

As a method of introducing an acid structure into polyurethane, for example, by substituting a part or all of the component (i) described in the above (2) to (4) with dimethylolalkanoic acid, a polyether polyol is preliminarily introduced. , polyester polyols, polyetherester polyols and other methods of introducing carboxyl groups. As a dimethylol alkanoic acid used here, a dimethylol acetic acid, a dimethylol propionic acid, a dimethylol butyric acid, etc. are mentioned, for example. A dimethylol alkanoic acid may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

Part or all of the acid structure contained in the polyurethane may also be neutralized by a nonvolatile base. By neutralizing the acid structure, even if the multilayer film has a thermal history of being exposed to a high temperature, the properties as an optical material can be maintained, or it can be bonded with other members with strong adhesive force. In addition, even if the acid structure is neutralized, the polyurethane particles can be dispersed in water without using a surfactant or with a small amount of the surfactant.

Among the acid structures contained in the polyurethane, the ratio of the neutralized acid structures is preferably 20% or more, particularly preferably 50% or more. By neutralizing 20% or more of the acid structure, even if the multilayer film has a thermal history of being exposed to a high temperature, the properties as an optical material can be maintained, or it can be bonded with other members with strong adhesive force.

In order to be able to react with the crosslinking agent, it is preferred that the polyurethane contains polar groups. As a polar group, a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, a sulfo group, etc. are mentioned. Among them, a methylol group, a hydroxyl group, a carboxyl group, and an amino group are preferable, a hydroxyl group and a carboxyl group are more preferable, and a carboxyl group is particularly preferable. The amount of the polar group in the polyurethane is preferably 0.0001 equivalent/1 kg or more, more preferably 0.001 equivalent/1 kg or more, and preferably 1 equivalent/1 kg or less.

As the polyurethane, those commercially available as aqueous polyurethane resins can also be used. The aqueous polyurethane resin is a composition containing polyurethane and water, and is usually a composition in which polyurethane and optional components contained as needed are dispersed in water. Examples of water-based polyurethane resins include "ADEKA BONTIGHTER" series by ADEKA, "OLESTER" series by Mitsui Chemicals, "VONDIC" series by DIC, "HYDRAN (WLS201, WLS202, etc.)" series, "IMPRANIL" series manufactured by Bayer Corporation, "POIZ" series manufactured by Kao Corporation, "SANPLEN" series manufactured by Sanyo Chemical Co., Ltd., "SUPERFLEX" series manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., "NEOREZ" series manufactured by Kusumoto Chemical Corporation , "Sancure" series manufactured by Lubrizol Company, etc. Moreover, urethane may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The glass transition temperature of the binder polymer is preferably 50°C or higher, more preferably 55°C or higher, particularly preferably 60°C or higher, preferably 150°C or lower, more preferably 125°C or lower, and particularly preferably 100°C or lower. By making the glass transition temperature of a binder polymer more than the lower limit of the said range, it can prevent that the conveying roller on the downstream side of a furnace is contaminated after exiting a drying furnace in a manufacturing process. Further, by being equal to or less than the upper limit value, curling of the multilayer film can be prevented.

In the fluid coating resin, the state of the binder polymer is arbitrary, and it may be dispersed in the form of particles or dissolved in other components such as a solvent. For example, in the case of using polyurethane as the binding polymer, the polyurethane is mostly dispersed in the form of particles. In this case, from the viewpoint of the optical properties of the multilayer film, the average particle diameter of the polyurethane particles is preferably 0.01 μm to 0.4 μm.

As the particles, inorganic particles formed of an inorganic material, organic particles formed of an organic material, and composite particles containing an inorganic material and an organic material in combination can be used. On the other hand, from the viewpoint of facilitating the formation of the resin layer, it is preferable to use water-dispersible particles. Examples of the material of the inorganic particles include inorganic oxides such as silica, titania, alumina, and zirconia; calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, silicic acid Aluminum, magnesium silicate, calcium phosphate, etc. Moreover, as a material of an organic particle, a silicone resin, a fluororesin, an acrylic resin, etc. are mentioned, for example. These may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

Among the materials of these exemplified particles, silica is preferred. Silica particles are excellent in the ability to suppress the occurrence of wrinkles and have excellent transparency, do not easily generate internal haze, and have no coloration, and therefore have little influence on the optical properties of the multilayer film. In addition, silica has good dispersibility and dispersion stability in the coating resin. Among the silica particles, amorphous colloidal silica particles are particularly preferred.

As the above silica particles, commercially available products can be used. Examples of commercially available products include EPOSTAR MX-050W (average particle size: 80 nm), SEAHOSTER KE-W10 (average particle size: 110 nm), and EPOSTAR MX-100W (average particle size: 150 nm to 200 nm) manufactured by Nippon Shokubai Corporation; SNOWTEX MP-2040 (average particle size: 150 nm to 200 nm) manufactured by Nissan Chemical Corporation.

Moreover, as a particle, the particle|grain which can form the protrusion which satisfy|fills the said conditions on the surface on the opposite side to the base film of a resin layer can be used. Generally, the protrusion height can be adjusted according to the size of the particles. In this case, the diameter of the particles does not directly become the height of the protrusions, but there is usually a correlation between the diameter of the particles and the height of the protrusions. Therefore, by adjusting the distribution of the particle diameters, it is possible to form the above-mentioned resin layer on the surface of the resin layer. Has widely distributed protrusions.

Usually, by using a combination of a plurality of particles having different average particle diameters, protrusions satisfying the above-mentioned conditions are formed on the surface of the resin layer. Therefore, the particles of the resin layer generally contain a combination of plural kinds of particles having different average particle diameters. By combining a plurality of types of particles having different average particle diameters, the particle size distribution of the particles contained in the resin layer as a whole can be widened, so that the height of the protrusions formed on the surface of the resin layer containing the particles can be adjusted to The distribution widens. Therefore, in this production method, in the step of mixing the particles and the binder polymer to obtain the coating resin, it is preferable to mix a plurality of types of particles having different average particle diameters with the binder polymer.

In addition, when a plurality of particles having different average particle diameters are used in combination, the average particle diameter of at least one particle is preferably larger than the thickness of the resin layer. In this way, by using particles having an average particle diameter larger than the thickness of the resin layer, protrusions satisfying the above-described conditions can be efficiently formed on the surface of the resin layer opposite to the base film. In addition, the average particle diameter of at least one of the plurality of particles may be smaller than the thickness of the resin layer.

Among them, the particles (S) having an average particle diameter of less than 150 nm and the particles (L) having an average particle diameter of 150 nm or more are preferably used in combination. Therefore, the particles of the resin layer preferably contain particles (S) having an average particle diameter of less than 150 nm and particles (L) having an average particle diameter of 150 nm or more in combination.

The average particle diameter of the particles (S) is usually 20 nm or more, preferably 30 nm or more, more preferably 40 nm or more, and usually less than 150 nm, preferably 140 nm or less, and more preferably 130 nm or less. By making the average particle diameter of the particle (S) more than the lower limit of the said range, protrusion can be stably formed in the surface of a resin layer. Moreover, by being below the upper limit, the distribution of the protrusion height on the surface of the resin layer can be widened.

In addition, the average particle diameter of the particles (S) is preferably 2 times or more, more preferably 3 times or more, particularly preferably 4 times or more, preferably 15 times or less, more preferably 15 times or less, with respect to the mode height of the protrusions formed on the surface of the resin layer. It is preferably 14 times or less, particularly preferably 13 times or less. Here, the mode height of the protrusions refers to the height of the protrusions having the most protrusions among the protrusion heights of 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, and 30 nm. By making the average particle diameter of the particle (S) more than the lower limit of the said range, protrusion can be stably formed in the surface of a resin layer. Moreover, by being below the upper limit, the distribution of the protrusion height on the surface of the resin layer can be widened.

The average particle diameter of the particles (S) is preferably 3 times or more, more preferably 4 times or more, particularly preferably 5 times or more, preferably 10 times or less, more preferably 8 times or less, and particularly preferably 7 times or less with respect to the thickness of the resin layer. . By making the average particle diameter of the particle (S) more than the lower limit of the said range, protrusion can be stably formed in the surface of a resin layer. Moreover, by being below the upper limit, the distribution of the protrusion height on the surface of the resin layer can be widened.

The amount of particles (S) is usually 2 parts by weight or more, preferably 3 parts by weight or more, more preferably 5 parts by weight or more, usually 24 parts by weight or less, preferably 20 parts by weight or less, relative to 100 parts by weight of the binder polymer. It is preferably 18 parts by weight or less. By making the quantity of particle (S) into the said range, the protrusion which satisfy|fills the said condition can be formed easily on the surface of a resin layer.

The average particle diameter of the particles (L) is usually 150 nm or more, preferably 160 nm or more, more preferably 170 nm or more, and usually 250 nm or less, preferably 230 nm or less, and more preferably 200 nm or less. By making the average particle diameter of the particle (L) more than the lower limit of the said range, the distribution of the protrusion height of the surface of a resin layer can be widened. Further, by being equal to or less than the upper limit value, the internal haze of the resin layer can be reduced.

In addition, the average particle diameter of the particles (L) is preferably 15 times or more, more preferably 16 times or more, particularly preferably 17 times or more, preferably 25 times or less, more preferably 25 times or less, with respect to the mode height of the protrusions formed on the surface of the resin layer. 23 times or less, particularly preferably 20 times or less. By making the average particle diameter of the particle (L) more than the lower limit of the said range, the distribution of the protrusion height of the surface of a resin layer can be widened. Moreover, by being below the upper limit, the internal haze of the resin layer can be reduced.

In addition, the average particle diameter of the particles (L) is preferably 2 times or more, more preferably 3 times or more, particularly preferably 4 times or more, preferably 10 times or less, more preferably 8 times or less, and particularly preferably 7 times the thickness of the resin layer. the following. By making the average particle diameter of the particle (L) more than the lower limit of the said range, the distribution of the protrusion height of the surface of a resin layer can be widened. Moreover, by being below the upper limit, the internal haze of the resin layer can be reduced.

In addition, the difference between the average particle diameter of the particles (S) and the average particle diameter of the particles (L) is preferably 70 nm or more, more preferably 100 nm or more, particularly preferably 120 nm or more, preferably 200 nm or less, more preferably 180 nm or less, and particularly preferably 160 nm or less. By setting the difference between the average particle diameter of the particles (S) and the average particle diameter of the particles (L) within the above range, protrusions satisfying the above conditions can be easily formed on the surface of the resin layer.

The amount of particles (L) is usually 5 parts by weight or more, preferably 6 parts by weight or more, more preferably 7 parts by weight or more, usually 20 parts by weight or less, preferably 18 parts by weight or less, relative to 100 parts by weight of the binder polymer. It is preferably 15 parts by weight or less. By making the quantity of particle (L) into the said range, the protrusion which satisfy|fills the said condition can be formed easily on the surface of a resin layer.

The difference between the amount of particles (L) and the amount of particles (S) is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, particularly preferably 2 parts by weight or more, and preferably 25 parts by weight relative to 100 parts by weight of the binder polymer part or less, more preferably 20 parts by weight or less, particularly preferably 15 parts by weight or less. By making the difference between the amount of particles (L) and the amount of particles (S) within the above range, protrusions satisfying the above conditions can be easily formed on the surface of the resin layer.

Usually, when the particles (S) and the particles (L) are used in combination as described above, peaks corresponding to the particles (S) and the particles (L) appear in the particle size distribution of the entire particles contained in the resin layer. However, even in this case, the distribution of the height of the protrusions formed on the surface of the resin layer usually shows a single peak. In this way, the distribution of particle diameters does not simply correspond to the distribution of protrusion heights. However, when a plurality of types of particles having different average particle diameters are combined in this way, the particle size distribution of the entire particles becomes wide, and the distribution of the height of the protrusions formed on the surface of the resin layer is also widened. Therefore, by utilizing the correlation between the distribution of the average particle diameter of such particles and the distribution of the height of the protrusions, protrusions satisfying the above conditions can be obtained.

In addition to the particles and the binder polymer, the coating resin may contain a crosslinking agent. The crosslinking agent reacts with the reactive group of the binder polymer to form a bond, thereby crosslinking the binder polymer. Therefore, for example, the adhesiveness between the resin layer and the base film, as well as the mechanical strength and heat-and-moisture resistance of the resin layer can be improved by crosslinking the binder polymer after applying the coating resin to the base film. For example, in the case where polyurethane is used as the binder polymer, the crosslinking agent may be usually unreacted with the carboxyl group and its acid anhydride group contained as the above-mentioned acid structure, and after the reaction of the components (i) and (ii) On the other hand, polar groups such as remaining hydroxyl groups react to form a cross-linked structure.

As the crosslinking agent, for example, a compound having, in one molecule, two or more functional groups capable of reacting with a reactive group of the binder polymer to form a bond can be used. Among them, as the crosslinking agent, a compound having a functional group capable of reacting with a carboxyl group or an acid anhydride group thereof is preferable.

Specific examples of the crosslinking agent include epoxy compounds, carbodiimide compounds, oxazoline compounds, isocyanate compounds, etc. In addition, a crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

As the epoxy compound, a polyfunctional epoxy compound having two or more epoxy groups in one molecule can be used. Among them, as the epoxy compound, an epoxy compound which is soluble in water or dispersible in water and emulsified is preferable. When the epoxy compound is soluble in water or emulsifiable, when the coating resin is an aqueous resin, the coating properties of the aqueous resin can be improved, and the resin layer can be easily produced. Here, the aqueous resin refers to a fluid resin containing solid components such as polymers in a state of being dissolved or dispersed in an aqueous solvent such as water.

Examples of the above epoxy compounds include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, and 1,6-hexanediol Diepoxide compounds obtained by etherifying 1 mole of glycols such as alcohol and neopentyl glycol and 2 moles of epichlorohydrin; polyols such as glycerin, polyglycerol, trimethylolpropane, pentaerythritol, and sorbitol 1 A polyepoxy compound obtained by etherification with more than 2 moles of epichlorohydrin and 2 moles of epichlorohydrin; 1 mole of dicarboxylic acids such as phthalic acid, terephthalic acid, oxalic acid, and adipic acid and 2 mol of diepoxide compound etc. obtained by esterification.

More specific examples of epoxy compounds include 1,4-bis(2',3'-glycidoxy)butane, 1,3,5-triglycidyl isocyanurate , 1,3-diglycidyl-5-(γ-acetoxy-β-oxypropyl) isocyanurate, sorbitol polyglycidyl ethers, polyglycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers Glycidyl ethers, diglycidyl polyglycidyl ether, 1,3,5-triglycidyl (2-hydroxyethyl) isocyanurate, glycerol polyglycidyl ether and trimethylol Propane polyglycidyl ethers, etc.

Moreover, as an example of the commercial item of an epoxy compound, "Denacol (Denacol EX-521, EX-614B etc.)" series by Nagase ChemteX company etc. are mentioned.

An epoxy compound may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The amount of the epoxy compound is usually 5 parts by weight or more, preferably 7 parts by weight or more, more preferably 10 parts by weight or more, usually 50 parts by weight or less, preferably 40 parts by weight or less, relative to 100 parts by weight of the binder polymer , more preferably 30 parts by weight or less. By making the amount of the epoxy compound more than the lower limit of the above-mentioned range, the reaction between the epoxy compound and the binder polymer proceeds sufficiently, and therefore, the mechanical strength of the resin layer can be appropriately increased. In addition, by being below the upper limit, the remaining of the unreacted epoxy compound can be reduced, and the mechanical strength of the resin layer can be appropriately improved.

In addition, the amount of the epoxy compound is preferably 0.2 times or more, more preferably 0.4 times or more, and particularly preferably 0.6 times on a weight basis relative to the amount of the epoxy compound equivalent to the polar group of the binder polymer. Above, preferably 1.4 times or less, more preferably 1.2 times or less, and particularly preferably 1.0 times or less. Here, the amount of the epoxy compound equivalent to the polar group of the binder polymer refers to the amount of the epoxy compound that can react with the total amount of the polar groups of the binder polymer not more or less. theoretical amount. The polar groups of the binding polymer can react with the epoxy groups of the epoxy compound. Therefore, by controlling the amount of the epoxy compound within the above-mentioned range, the reaction between the polar group and the epoxy compound can be advanced to an appropriate degree, thereby effectively improving the mechanical strength of the resin layer.

As the carbodiimide compound, a compound having two or more carbodiimide groups in one molecule can be used. The carbodiimide compound can be produced using organic isocyanates such as organic monoisocyanates, organic diisocyanates, and organic triisocyanates as raw materials. Examples of these organic isocyanates include aromatic isocyanates, aliphatic isocyanates, and mixtures thereof. Therefore, as the organic group which the organic isocyanate has, either aromatic or aliphatic may be used, and an aromatic organic group and an aliphatic organic group may be used in combination. Among them, from the viewpoint of reactivity, an organic isocyanate having an aliphatic organic group is particularly preferable. In general, carbodiimide compounds can be synthesized by condensation reaction of organic diisocyanates.

Specific examples of organic isocyanates include 4,4'-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4 -toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, Organic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate and 1,3-phenylene diisocyanate; organic monoisocyanates such as isophorone isocyanate, phenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate and naphthyl isocyanate Isocyanates.

Examples of commercially available carbodiimide compounds include "Carbodilite (Carbodilite V-02, V-02-L2, SV-02, V-Carbodilite V-02, V-02-L2, SV-02, V- 04, E-02, etc.)” series.

A carbodiimide compound may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The amount of the carbodiimide compound is usually 1 part by weight or more, preferably 3 parts by weight or more, usually 40 parts by weight or less, preferably 30 parts by weight or less, relative to 100 parts by weight of the binder polymer. By making the amount of the carbodiimide compound more than the lower limit of the above range, the reaction between the carbodiimide compound and the binder polymer proceeds sufficiently, and therefore, the mechanical strength of the resin layer can be appropriately increased. In addition, by setting the amount of the carbodiimide compound to be equal to or less than the upper limit value, the residual of the unreacted carbodiimide compound can be reduced, and the mechanical strength of the resin layer can be appropriately improved.

as As the oxazoline compound, those represented by the following formula (I) can be used. oxazoline-based polymers. In the following formula (I), R ¹ , R ² , R ³ and R ⁴ are the same or different, and represent any group selected from a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, a phenyl group and a substituted phenyl group .

[Chemical formula 1]

Should The oxazoline compound can contain addition polymerizable The oxazoline is produced by performing solution polymerization in an aqueous medium by a known polymerization method as a monomer component containing an arbitrary unsaturated monomer as required. as addition polymerizable As an oxazoline, the compound represented by following formula (II) is mentioned, for example. In the following formula (II), R ¹ , R ² , R ³ and R ⁴ have the same definitions as in the formula (I). In addition, R ⁵ represents an acyclic organic group having an addition polymerizable unsaturated bond.

[Chemical formula 2]

as addition polymerizable Specific examples of oxazolines include 2-vinyl-2- oxazoline, 2-vinyl-4-methyl-2- oxazoline, 2-vinyl-5-methyl-2- oxazoline, 2-isopropenyl-2- oxazoline, 2-isopropenyl-4-methyl-2- oxazoline, 2-isopropenyl-5-ethyl-2- oxazoline etc. Moreover, these may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Among them, 2-isopropenyl-2- The oxazoline is also easy to obtain industrially, so it is preferable.

The addition polymerizability The amount of oxazoline relative to 100 weight part of all monomer components used for manufacture of an oxazoline compound, Preferably it is 3 weight part or more. Thus, the inclusion of When the coating resin of the oxazoline compound is cured, the curing can be sufficiently advanced, and a resin layer excellent in durability and water resistance can be obtained.

as available for Arbitrary unsaturated monomers for the production of oxazoline compounds can be used with addition polymerizable oxazoline copolymerization without Any monomer in which an oxazoline group reacts. Such arbitrary unsaturated monomers can be arbitrarily selected from the above-mentioned monomers and used.

as Examples of commercial products of the oxazoline compound include EPOCROS WS-500 and WS-700 manufactured by Nippon Shokubai Corporation among water-soluble types. Moreover, as an emulsion type, EPOCROS K-2010, K-2020, and K-2030 by Nippon Shokubai Corporation are mentioned, for example. Among them, the water-soluble type having high reactivity with the binder polymer contained in the coating resin is preferable.

in addition, An oxazoline compound may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

as The amount of the oxazoline compound can be set so that the polar group of the binding polymer is oxazoline compounds have Molar ratio of oxazoline groups (moles of polar groups/ moles of oxazoline groups) are within the given ranges. Specifically, the molar ratio can be set to be 100/20 to 100/100. By making the said molar ratio more than the lower limit of the said range, the unreacted polar group can be prevented from remaining. In addition, by making the above molar ratio equal to or less than the upper limit value, it is possible to prevent excess The generation of oxazoline groups prevents the hydrophilic groups from becoming excessive.

In addition, when the binding polymer has a carboxyl group and the carboxyl group is neutralized, the binding polymer and the In the reaction of oxazoline compounds, The oxazoline group does not easily react with the carboxylate. Therefore, the reactivity can be controlled by adjusting the kind of the nonvolatile base used for neutralization and the degree of nonvolatileness.

As the isocyanate compound, a compound containing two or more isocyanate groups in one molecule can be used. These isocyanate compounds may be aliphatic compounds, alicyclic compounds, or aromatic compounds. As a specific example of an isocyanate compound, the same example as (ii) component demonstrated as a raw material of a polyurethane is mentioned.

Among the above-mentioned crosslinking agents, epoxy compounds and carbodiimide compounds are preferable, and epoxy compounds are particularly preferable. When an epoxy compound is used as a crosslinking agent, the adhesiveness between a resin layer and a base film can be improved significantly especially. In addition, if a carbodiimide compound is used as a crosslinking agent, the pot life of the coating resin can be improved.

Furthermore, the coating resin may contain a non-volatile base in addition to the particles and the binding polymer. As a nonvolatile base, the base which is substantially nonvolatile under the processing conditions at the time of apply|coating a coating resin to a base film and drying it is mentioned. As the above-mentioned treatment conditions, for example, a treatment of standing at 80° C. for 1 hour can be exemplified. Here, "substantially nonvolatile" generally means that the reduction amount of the nonvolatile base is 80% or less. Such a nonvolatile base can function as a neutralizer for neutralizing the acid structure contained in binder polymers such as polyurethane.

As a nonvolatile base, an inorganic base can be used, and an organic base can also be used. Among them, organic bases having a boiling point of 100°C or higher are preferable, amine compounds having a boiling point of 100°C or higher are more preferable, and amine compounds having a boiling point of 200°C or higher are particularly preferable. In addition, the organic base may be a low molecular compound or a polymer.

If an example of a nonvolatile base is mentioned, as an inorganic base, sodium hydroxide and potassium hydroxide are mentioned, for example. In addition, examples of the organic base include 2-amino-2-methyl-1-propanol (AMP), triethanolamine, triisopropanolamine (TIPA), monoethanolamine, diethanolamine, tri[(2 -Hydroxy)-1-propyl]amine, 2-amino-2-methyl-1,3-propanediol (AMPD), 2-amino-2-hydroxymethyl-1,3-propane potassium hydroxide, zinc ammonium Complex, copper ammonium complex, silver ammonium complex, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyl N-β(aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N,N-bis( Trimethylsilyl)urea, 3-ureidopropyltrimethoxysilane, 3-aminopropyl-tris(2-methoxy-ethoxy-ethoxy)silane, N-methyl-3 -Aminopropyltrimethoxycarboxylic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide Alkanoic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, quinoline, picoline, pyridine, morpholine, piperazine, cyclohexylamine, hexamethylenediamine, N, N-dimethylformamide, ethylenediamine, diethylenetriamine, tetraethylenepentamine, pentaethylenepentamine, monoethanolamine, diethanolamine, isopropanolamine, N,N-diethyl methylethanolamine, N,N-dimethylethanolamine, aminoethylethanolamine, N-methyl-N-N-diethanolamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-Methylpiperazine, 2,5-Dimethylpiperazine, Isophoronediamine, 4,4'-Dicyclohexylmethanediamine, 3,3'-Dimethyl-dicyclohexylmethanediamine Amine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, aminopropylethanolamine, aminohexylethanolamine, aminoethylpropanolamine, aminopropylpropanolamine, Aminohexylpropanolamine, diethylenetriamine, dipropylenetriimidazole, 1-(2-aminoethyl)-2-methylimidazole, 1-(2-aminoethyl)-2-ethyl Imidazole, 2-aminoimidazole sulfate, 2-(2-aminoethyl)-benzimidazole, pyrazole, 5-aminopyrazole, 1-methyl-5-aminopyrazole, 1-isopropyl-5 -Aminopyrazole, 1-benzyl-5-aminopyrazole, 1,3-dimethyl-5-aminopyrazole, 1-isopropyl-3-methyl-5-aminopyrazole, 1-benzyl yl-3-methyl-5-aminopyrazole, 1-methyl-4-chloro-5-aminopyrazole, 1-methyl-4-cyano-5-aminopyrazole, 1-isopropyl- 4-Chloro-5-aminopyrazole, 3-methyl-4-chloro-5-aminopyrazole, 1-benzyl-4-chloro-5-aminopyrazole, amino resins (e.g., 1,3-diaminopyrazole) Methyl-4-chloro-melamine resin, urea-formaldehyde resin, guanamine resin, etc.) and the like. Moreover, these may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The amount of the non-volatile base is usually 0.5 parts by weight or more, preferably 1 part by weight or more, more preferably 2 parts by weight or more, usually 30 parts by weight or less, preferably 20 parts by weight relative to 100 parts by weight of the binder polymer Hereinafter, it is more preferably 10 parts by weight or less. Sufficient adhesive force can be obtained by making the quantity of a nonvolatile base more than the lower limit of the said range. Moreover, discoloration of the polarizing plate made of polyvinyl alcohol can be prevented by making the quantity of a nonvolatile base less than an upper limit.

Furthermore, the coating resin may contain a wetting agent in addition to the particles and the binding polymer. By using a wetting agent, the coating properties when coating the coating resin on the base film can be improved.

As the wetting agent, for example, an acetylenic surfactant, a fluorine-based surfactant, or the like can be used. As the acetylenic surfactant, for example, Surfynol series, Dynol series, etc. manufactured by Air Products and Chemicals can be used. Moreover, as a fluorine type surfactant, for example, MEGAFAC series by DIC Corporation, Ftergent series by Neos Corporation, SURFLON series by AGC Corporation, etc. can be used. As the wetting agent, an acetylenic surfactant is preferably used from the viewpoint of repeatability.

Moreover, these wetting agents may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The blending amount of the wetting agent is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 5% by weight or less, preferably 4% by weight relative to the solid content of the coating resin. % by weight or less, more preferably 3% by weight or less. Sufficient coatability can be obtained by making the quantity of a wetting agent more than the lower limit of the said range. In addition, when it is below the upper limit value, the bleed-out of the wetting agent can be suppressed, and the recoatability can be further improved.

The coating resin usually contains a solvent. As the solvent, water or a water-soluble solvent is used. As a water-soluble solvent, methanol, ethanol, isopropanol, acetone, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, etc. are mentioned, for example. Among them, as the solvent, water is preferably used. In addition, a solvent may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The amount of the solvent can be set so that the viscosity of the coating resin is in a range suitable for coating. Usually, the amount of the solvent is set so that the solid content concentration of the coating resin falls within a desired range. The above-mentioned desired range is preferably 0.5% by weight or more, more preferably 1% by weight or more, preferably 15% by weight or less, and more preferably 10% by weight or less. Thereby, the handleability and coatability of the coating resin can be made favorable.

The coating resin may contain a curing accelerator in combination with the above-mentioned crosslinking agent. For example, when an epoxy compound is used as a crosslinking agent, as a curing accelerator, a tertiary amine compound (a compound having a 2,2,6,6-tetramethylpiperidinyl group having a tertiary amine at the 4-position) is preferable except), boron trifluoride complexes, etc. Moreover, a hardening accelerator may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The amount of the curing accelerator is usually 0.001 part by weight or more, preferably 0.01 part by weight or more, more preferably 0.03 part by weight or more, usually 30 parts by weight or less, preferably 10 parts by weight or less, more preferably 100 parts by weight of the binder polymer. 5 parts by weight or less.

The coating resin may contain a curing adjuvant in combination with the above-mentioned crosslinking agent. Specific examples of curing aids include oxime-nitroso-based curing aids such as quinone dioxime, benzoquinone dioxime, and p-nitrosophenol; N,N-m-phenylenebismaleimide Maleimide curing assistants such as amines; Allyl curing assistants such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, etc.; Alcohol dimethacrylate, trimethylolpropane trimethacrylate and other methacrylate curing assistants; vinyl toluene, ethyl vinylbenzene, divinylbenzene and other vinyl curing assistants; etc. . Moreover, a hardening adjuvant may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

The amount of the curing assistant is usually 1 part by weight or more, preferably 10 parts by weight or more, and usually 100 parts by weight or less, preferably 50 parts by weight or less, relative to 100 parts by weight of the crosslinking agent.

The coating resin may also contain, for example, a heat-resistant stabilizer, a weather-resistant stabilizer, a leveling agent, a surfactant, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, an antifogging agent, as long as the effects of the present invention are not significantly impaired agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, etc. In addition, these substances may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

In the step of obtaining the coating resin, the particles, the binder polymer, and optionally a crosslinking agent, a nonvolatile base, a wetting agent, a solvent, and optional components are mixed to obtain a fluid coating resin. It is preferable that the obtained coating resin can be uniformly coated on the surface of the base film. From the viewpoint of having such excellent coatability, the viscosity of the coating resin is preferably 15 mPa·s or less, particularly preferably 10 mPa·s or less. Here, the said viscosity is the value measured on the condition of 25 degreeC with a tuning-fork-type vibration viscometer. This viscosity can be adjusted according to the ratio of a solvent, the particle diameter of a particle, etc., for example.

After the coating resin is obtained, a step of coating the coating resin on the base film to form a resin-coated film is performed. In this case, the coating resin is usually directly provided on the surface of the base film without intervening through other layers such as an adhesive layer. In addition, the coating resin may be coated only on one side of the base film, or may be coated on both sides. Among them, from the viewpoint of suppressing the production cost of the multilayer film, it is preferable to apply the coating resin only to one side of the base film.

When coating the coating resin on the base film, any coating method can be employed. Specific coating methods include, for example, wire bar coating, dipping, spray coating, spin coating, roll coating, gravure coating, air knife coating, curtain coating, and slide coating. Coating method, extrusion coating method, etc.

After the resin-coated film is formed on the base film, a step of curing and/or drying the resin-coated film to obtain a resin layer is performed. Usually, since the coating resin contains a solvent, the step of obtaining a resin layer includes drying and removing the solvent. The drying method is arbitrary, and for example, it can be performed by an arbitrary method such as drying under reduced pressure and drying by heating. Among them, from the viewpoint of rapidly advancing reactions such as a crosslinking reaction in the coating resin, it is preferable to cure and dry the coating resin by heating and drying. In the case of heat drying, a crosslinking reaction of the binding polymer usually occurs.

In the case of curing and drying the coating resin by heating, the heating temperature is appropriately set within a range capable of drying the solvent and curing the polymer component in the coating resin. In addition, when using a stretched film as a base film and it is not desired to change the retardation exhibited by the base film, the heating temperature is preferably set so that orientation relaxation does not occur in the base film. temperature. Specifically, when the glass transition temperature of the material forming the base film is defined as Tg, it is preferably (Tg-30°C) or higher, more preferably (Tg-10°C) or higher, and preferably (Tg+60°C) ) or less, more preferably (Tg+50°C) or less.

In addition, the above-mentioned manufacturing method may include arbitrary steps in addition to the above-mentioned steps. For example, the production method may include a step of subjecting the surface of the base film to a modification treatment before forming the resin-coated film on the base film. Thereby, the adhesiveness of a base film and a resin layer can be improved. As the surface modification treatment of the base film, for example, energy ray irradiation treatment, chemical treatment, and the like can be mentioned. Examples of the energy ray irradiation treatment include corona discharge treatment, plasma treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, etc. From the viewpoint of treatment efficiency, corona discharge treatment and plasma treatment are preferred, and particularly preferred Corona discharge treatment. Moreover, as a chemical|drug process, a saponification process is mentioned, for example. In addition, as the chemical treatment, for example, a method of immersing the base film in an aqueous solution of an oxidizing agent such as potassium dichromate solution and concentrated sulfuric acid, and then washing with water is exemplified.

Moreover, the said manufacturing method may include the process of carrying out the hydrophilization surface treatment to the surface which has a protrusion of a resin layer. The surface which has a protrusion of a resin layer normally becomes the bonding surface at the time of bonding a multilayer film and another member. Therefore, the adhesiveness of the multilayer film and other members can be remarkably improved by further increasing the hydrophilicity of the surface having the protrusions of the resin layer.

Examples of the hydrophilization surface treatment include corona discharge treatment, plasma treatment, saponification treatment, ultraviolet irradiation treatment, and the like. Among them, from the viewpoint of treatment efficiency and the like, corona discharge treatment and plasma treatment are preferable, and corona discharge treatment is more preferable. In addition, as the plasma treatment, atmospheric pressure plasma treatment is preferable.

By the above-described production method, a resin layer can be formed on the base film. As shown in FIG. 1 , the surface 121 of the resin layer 120 obtained in this way on the opposite side to the base film 110 has protrusions 122, and thus has good sliding properties. Therefore, the coefficient of static friction between the surface 121 of the resin layer 120 opposite to the base film 110 and the surface 111 of the base film 110 opposite to the resin layer 120 can be reduced. The static friction coefficient is preferably 0.3 to 0.5. Thereby, when the multilayer film 100 is wound into a roll shape, the occurrence of convex defects can be effectively suppressed.

Furthermore, the resin layer does not contain a large amount of particles to such an extent that the internal haze of the resin layer increases. In general, particles with a small particle size have a small weight per particle. Therefore, even if the amount on a weight basis is small, the number of the particles may be large. Therefore, by using a combination of particles with a small particle size and particles with a large particle size in this way, the amount of particles can be reduced compared to forming a large number of protrusions on the surface of the resin layer to the extent that the sliding properties can be improved. Therefore, the internal haze of the resin layer can be reduced.

The thickness of the resin layer is usually 10 nm or more, preferably 15 nm or more, more preferably 20 nm or more, and usually 100 nm or less, preferably 80 nm or less, and more preferably 70 nm or less. The mechanical strength of a resin layer can be improved by making the thickness of a resin layer more than the lower limit of the said range. Further, by being equal to or less than the upper limit value, desired protrusions can be stably formed on the surface of the resin layer, so that the sliding property of the surface of the resin layer can be effectively improved. In addition, by reducing the thickness of the resin layer as described above, it is generally possible to make the resin layer less likely to affect the optical properties of the base film. Therefore, it is not necessary to change the configuration of the resin layer in order to adjust the optical properties of the multilayer film, so that the adjustment of the optical properties of the multilayer film can be easily performed.

In addition, the thickness of the resin layer is preferably 1 time or more, more preferably 2 times or more, particularly preferably 3 times or more, preferably 10 times or less, more preferably 7 times or less, with respect to the mode height of the protrusions formed on the surface of the resin layer, It is especially preferable that it is 5 times or less. The haze value can be reduced by making the thickness of the resin layer more than the lower limit value of the above-mentioned range. In addition, by being below the upper limit value, sufficient lubricity without causing surface defects can be imparted to the film surface.

The difference in refractive index at the interface between the base film and the resin layer is preferably 0.05 or less. When the difference in refractive index is within the above-mentioned range, the loss of light through the multilayer film can be suppressed.

[4. Physical properties of multilayer films]

Since the multilayer film of the present invention includes the above-mentioned resin layer, the surface on the resin layer side has high sliding properties. Therefore, it can suppress the generation|occurrence|production of a convex defect after winding up in a roll shape and making it into a film roll.

In addition, since the multilayer film of the present invention includes a resin layer having a small internal haze as described above, the internal haze can be reduced. Specifically, the internal haze of the multilayer film is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. Here, the internal haze of the multilayer film can be measured by the following method.

Prepare a quartz cell with a height of 55 mm, a width of 36 mm, and an optical path length of 10 mm. The quartz cell is filled with silicone oil. The multilayer film was put into this silicone oil to obtain a measurement sample. Using the measurement sample thus prepared, the internal haze of the multilayer film was measured with a haze meter.

In addition, from the viewpoint of stably exerting a function as an optical film, it is preferable that the total light transmittance of the multilayer film is high. Specifically, the total light transmittance in terms of thickness of 1 mm is preferably 80% or more, and more preferably 90% or more. Here, the total light transmittance can be measured based on JIS K0115 using a spectrophotometer (manufactured by JASCO Corporation, UV-visible-near-infrared spectrophotometer "V-570").

The multilayer film may be a retardation film having retardation in the in-plane direction or the thickness direction. The specific retardation range can be set according to the application of the multilayer film. If a specific range is given, the retardation Re in the in-plane direction can usually be appropriately selected in the range of 10 nm to 500 nm, and the retardation Rth in the thickness direction can be appropriately selected in the range of -500 nm to 500 nm.

In addition, the deviation of the retardation Re in the in-plane direction of the multilayer film is usually within 10 nm, preferably within 5 nm, and more preferably within 2 nm. By making the variation of the retardation Re in the in-plane direction within the above-mentioned range, when the multilayer film is used as a retardation film for a liquid crystal display device, the display quality can be improved. Here, the variation in the retardation Re in the in-plane direction refers to the difference between the maximum value and the minimum value of the retardation Re in the in-plane direction when the retardation Re in the in-plane direction at a light incident angle of 0° is measured along the width direction of the film. . Here, the light incident angle of 0° refers to a state in which the incident light ray is perpendicular to the surface of the film.

The amount of residual volatile components in the multilayer film is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and more preferably 0.02% by weight or less. By setting the amount of the volatile component within the above-mentioned range, dimensional stability is improved, and changes over time in retardation Re in the in-plane direction and retardation Rth in the thickness direction of the multilayer film can be reduced.

The dimension in the width direction of the multilayer film may be, for example, 1000 mm to 3000 mm. In addition, the dimension in the longitudinal direction of the multilayer film is not limited, but a long film is preferable. Here, a "long" film means a length of at least 5 times or more, preferably 10 times or more, of the width of the film, and specifically means that it can be wound into a roll for storage or transport. length of film.

[5. Manufacturing method of multilayer film]

The multilayer film of the present invention can be produced by a production method including a step of preparing a base film and a step of producing a resin layer on the prepared base film. Here, as described above, the step of producing the resin layer on the base film includes the step of obtaining a fluid coating resin, the step of applying the coating resin on the base film to form a resin-coated film, and The process of hardening and/or drying the film of the coating resin formed on the base film to obtain a resin layer. Therefore, the multilayer film can be produced by, for example, a production method including the following steps: a step of preparing a base film; a step of mixing a plurality of particles with different average particle diameters and a binder polymer to obtain a fluid coating resin a step of applying a coating resin on a base film to form a resin-coated film; and a step of curing and/or drying the coating resin film formed on the base film to obtain a resin layer.

In addition, when the multilayer film includes arbitrary layers other than the base film and the resin layer, the step of providing the arbitrary layers can be performed at any point in the manufacturing method of the multilayer film. In addition, the surface on the opposite side to the base film of the resin layer is usually exposed as the outermost surface of the multilayer film. Therefore, an arbitrary layer is usually provided on the surface of the base film on the opposite side to the resin layer.

Moreover, the process of extending|stretching a base film, a resin layer, and a multilayer film can also be performed at any point in the manufacturing method of a multilayer film.

Moreover, the process of winding up a multilayer film into a roll shape can be performed.

[6. Use of multilayer films]

The multilayer film of the present invention is generally used as an optical film. As an example of the optical film used as a multilayer film, a protective film, a retardation film, an optical compensation film, etc. are mentioned. Among them, the multilayer film of the present invention is preferably used as a retardation film or a polarizer protective film, and is particularly preferably used as a polarizer protective film.

The polarizer usually has a polarizer and a polarizer protective film. Therefore, when using the multilayer film of the present invention as a polarizer protective film, the multilayer film of the present invention is usually bonded to a polarizer. At this time, the multilayer film and the polarizer are usually bonded together on the surface on the resin layer side of the multilayer film.

When bonding the multilayer film and the polarizer, the multilayer film and the polarizer may be directly bonded without intervening through the adhesive layer, or may be bonded through the adhesive layer. In addition, the multilayer film may be bonded only on one side of the polarizer, or may be bonded on both sides. When the multilayer film is bonded only on one side of the polarizer, another film with high transparency may be bonded on the other side of the polarizer.

The polarizer can be produced, for example, by uniaxial stretching in a boric acid bath after adsorbing iodine or a dichroic dye to a polyvinyl alcohol film. Moreover, it can also manufacture by making a polyvinyl alcohol film adsorb|suck iodine or a dichroic dye, and extending it, for example, and modifying a part of the polyvinyl alcohol unit in a molecular chain to a polyvinylidene unit, for example. Further, as the polarizer, for example, a polarizer having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer, a multilayer polarizer, and a cholesteric liquid crystal polarizer, can be used. Among them, a polarizer containing polyvinyl alcohol is preferable. The polarization degree of the polarizer is preferably 98% or more, and more preferably 99% or more. The average thickness of the polarizer is preferably 5 μm to 80 μm.

As the adhesive for bonding the polarizer and the multilayer film, an optically transparent adhesive can be used. As this adhesive agent, an aqueous adhesive agent, a solvent type adhesive agent, a two-component curable adhesive agent, a photocurable adhesive agent, a pressure-sensitive adhesive agent etc. are mentioned, for example. Among them, aqueous adhesives are preferred, and polyvinyl alcohol-based aqueous adhesives are particularly preferred. Moreover, an adhesive agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

As a photocurable adhesive, for example, an acrylate-based adhesive containing urethane (meth)acrylate, hydroxyalkyl (meth)acrylate, and an acrylamide derivative can be used.

For example, urethane (meth)acrylate can be obtained by reacting a polyisocyanate and a polyol, and then further reacting a hydroxyl-containing (meth)acrylic compound and, if necessary, a hydroxyl-containing allyl ether compound. Obtained from oligomers containing radically polymerizable unsaturated groups. Moreover, urethane (meth)acrylate can also be obtained, for example, by making a hydroxyl-containing (meth)acrylic compound and a polyol react, and further reacting with a polyisocyanate.

As the urethane (meth)acrylate, since it is easy to balance the adhesive strength, flexibility, photocurability, viscosity, etc., it is preferable to use 2 to 3 double bonds per molecule, and one double bond per molecule is preferably used. Urethane (meth)acrylate having a number-average molecular weight of double bonds of 500 to 3,000.

The amount of the urethane (meth)acrylate in the photocurable adhesive is usually 30% by weight to 50% by weight. Embrittlement of an adhesive bond layer can be prevented by making the quantity of a urethane (meth)acrylate more than the lower limit of the said range. In addition, by being below the upper limit value, the viscosity of the adhesive can be reduced, and the adhesive strength can be improved.

As hydroxyalkyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate are mentioned, for example. Among them, hydroxyethyl methacrylate is particularly preferred.

The amount of the hydroxyalkyl (meth)acrylate in the photocurable adhesive is usually 13% by weight to 40% by weight. By making the amount of hydroxyalkyl (meth)acrylate more than the lower limit of the above-mentioned range, the hydrophilicity of the entire adhesive can be improved, and therefore, the adhesion to a polyvinyl alcohol-based polarizing film in particular can be improved strength. Moreover, by being below the upper limit, the adhesive layer can be prevented from becoming brittle, and the photocurability of the adhesive can be improved.

Examples of acrylamide derivatives include N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-dimethylaminoethylacrylamide, N,N-dimethylacrylamide aminopropylacrylamide, N-isopropylacrylamide, N,N-dimethylaminopropylacrylamide, N-hydroxyethylacrylamide. Among them, N,N-diethylacrylamide, N-isopropylacrylamide, N,N-dimethylaminopropylacrylamide, and N-hydroxyethylacrylamide are particularly preferred.

The amount of the acrylamide derivative in the photocurable adhesive is usually 0 to 30% by weight, preferably 1 to 30% by weight.

The photocurable adhesive preferably contains 30 to 40 wt % of isobornyl (meth)acrylate in addition to the above-mentioned components. By containing isobornyl (meth)acrylate, heat resistance can be imparted to the adhesive layer. In addition, the viscosity for improving coating properties can be adjusted without causing a decrease in adhesive properties.

The photocurable adhesive preferably contains a photopolymerization initiator. Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthracene Quinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone Ketone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzoin dimethyl ether, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one , 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethyl thioxanthone, 2-isopropyl thioxanthone, 2-chlorothioxanthone, 2-methyl thioxanthone base-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc. Moreover, the quantity of the photoinitiator in a photocurable adhesive agent is 2 weight% - 10 weight% normally.

The viscosity of the adhesive at 23°C is usually 20 mPa or more, preferably 30 mPa or more, more preferably 50 mPa or more, usually 5000 mPa or less, preferably 3000 mPa or less, and more preferably 1500 mPa or less.

The average thickness of the adhesive bond layer is preferably 0.05 μm or more, more preferably 0.1 μm or more, preferably 5 μm or less, and more preferably 1 μm or less.

There is no limitation on the method of bonding the multilayer film to the polarizer. For example, it is preferable to apply an adhesive to one side of the polarizer as necessary, and to bond the polarizer and the multilayer film together using a roll laminator, and to dry or irradiate light such as ultraviolet light as necessary. .

Example

Hereinafter, the present invention will be specifically described with reference to the embodiments. However, the present invention is not limited to the examples shown below.

In the following description, "%", "ppm" and "part" indicating the amount are based on weight unless otherwise specified. In addition, the following operations were performed in normal temperature and normal pressure atmosphere unless otherwise specified.

[Evaluation method]

[Measurement method of height and number of protrusions]

Using a micro-shape measuring device (“ET4000M” manufactured by Kosaka Laboratory), the protrusions present on the surface opposite to the base film of the resin layer of the multilayer film were measured with a cutoff value of 0.8 mm and a measurement range of 1 mm×1 mm. height and quantity. This measurement is performed in the center part of the width direction of a multilayer film.

[Measuring method of internal haze]

A quartz cell with a height of 55 mm, a width of 36 mm, and an optical path length of 10 mm was prepared. Silicone oil ("SH710" manufactured by TorayDow Corning) was filled in the quartz cell. The multilayer film was put into the silicone oil to prepare a measurement sample. Using the measurement sample thus prepared, the internal haze of the multilayer film was measured with a haze meter (“NDH-2000” manufactured by Nippon Denshoku Kogyo Co., Ltd.).

[Measuring method of peel strength]

(Manufacturing method of adhesive)

In a 100-g glass container, 66.5 g of pure water was measured. This pure water was heated to 80 degreeC, and it stirred with a stirring bar. 3.5 g of polyvinyl alcohol ("GOHSEFIMER Z200" manufactured by Nippon Synthetic Chemical Co., Ltd.) was gradually added to the pure water to completely dissolve it, thereby obtaining a 5% polyvinyl alcohol solution. Then, the polyvinyl alcohol solution was returned to room temperature. To this polyvinyl alcohol solution, 1% of glyoxal with respect to the polyvinyl alcohol in the polyvinyl alcohol solution was added as a crosslinking agent, and the mixture was sufficiently stirred to obtain an adhesive.

(Manufacturing method of polarizer)

A polyvinyl alcohol film with a thickness of 80 μm was dyed in a 0.3% iodine aqueous solution. Then, the dyed polyvinyl alcohol film was stretched to 5 times in an aqueous solution containing 4% of boric acid and 2% of potassium iodide, and dried at 50° C. for 4 minutes to obtain a polarizer.

(Manufacture of polarizer)

The above-mentioned adhesive was applied on the resin layer side surface of the multilayer film using a bar coater. The polarizer was mounted on this adhesive bond layer, and was pressed with a roll laminator to bond the multilayer film and the polarizer. Thereby, the polarizing plate provided with a polarizer, an adhesive bond layer, a resin layer, and a base material film in this order was obtained.

(Measurement of peel strength)

The produced polarizing plate was cut into a width of 10 mm to obtain a test piece. The surface of the multilayer film side of this test piece was bonded to the surface of the glass plate with an adhesive ("No. 5601" manufactured by Nitto Denko Corporation). Then, the polarizer of the test piece was clamped with the upper chuck of a precision universal testing machine (“Autograph AGS-5kNG” manufactured by Shimadzu Corporation), and the polarizer of the test piece was moved at a speed of 20 mm/min toward the surface perpendicular to the glass plate. Pull in the direction. As the polarizer was pulled, peeling occurred at the interface between the resin layer and the base film. At this time, the magnitude of the force pulling the polarizer was measured. The average value was calculated|required from the measured value in the range of 50 mm in which the magnitude of the force measured in the longitudinal direction of the test piece was stable, and the average value was used as the peel strength.

[Evaluation method of roll appearance]

About the external appearance of the film roll which wound up the multilayer film 3000m, it evaluated by visual inspection and tactile discrimination.

The case where there were no polygonal depressions on the peripheral surface of the film roll was evaluated as "good", and the case where polygonal depressions were present on the peripheral surface of the film roll was evaluated as "poor".

[Evaluation method of surface state of multilayer film]

Samples were cut from the multilayer films. Two linear polarizers were prepared, and the sample cut out from the multilayer film was sandwiched between these linear polarizers. At this time, the two linear polarizers were made to be crossed Nicol, and the polarized light transmission axes viewed from the thickness direction were perpendicular to each other. As a result, a laminate including a linear polarizer, a sample, and a linear polarizer in this order was obtained.

The above-mentioned laminate was observed from the thickness direction. The light leakage portion was regarded as an optical defect, and the number of optical defects was counted. Here, the light leakage portion refers to a portion where the light transmitted through the laminate can be observed. In addition, the area of the sample used for the measurement was 100 m ² . The smaller the number of light leaking parts, the less wrinkles and creases are present in the multilayer film, and the better the surface state is.

[Example 1]

(Manufacture of water-based resin)

840 parts of polyester polyol ("MAXIMOL FSK-2000" manufactured by Kawasaki Chemical Industry Co., Ltd.; hydroxyl value 56 mgKOH/g), 119 parts of toluene diisocyanate, And 200 parts of methyl ethyl ketone, it was made to react at 75 degreeC for 1 hour, introducing nitrogen gas.

It cooled to 60 degreeC after completion|finish of reaction, 35.6 parts of dimethylolpropionic acids were added, and it reacted at 75 degreeC. Thus, a polyurethane solution containing an acid structure was obtained. The isocyanate group (-NCO group) content of the polyurethane contained in this solution was 0.5%.

Then, the polyurethane solution was cooled to 40°C. To the cooled polyurethane solution, 1,500 parts of water and 120 parts of isophthalic hydrazide (boiling point of 224° C. or higher) as a nonvolatile base (7 parts with respect to 100 parts of polyurethane) were added, and the homogenizer was used. It was emulsified by stirring at a high speed. From this emulsified liquid, methyl ethyl ketone was distilled off under heating and reduced pressure, and a neutralized polyurethane aqueous dispersion was obtained. The solid content concentration of this aqueous dispersion was 40%.

Then, only an amount such that the amount of the polyurethane contained therein was 100 parts was extracted from the aqueous dispersion of the polyurethane. 40 parts of glycerol polyglycidyl ether ("Denacol EX-313" manufactured by Nagase ChemteX; epoxy equivalent: 141 g/eq) and an average particle diameter of 40 nm were blended into the water dispersion of the separated polyurethane as an epoxy compound. 24 parts of silica particles (“UFP-80” manufactured by Denki Chemical Industry Co., Ltd.), 20 parts of silica particles (“SNOWTEX MP-2040” manufactured by Nissan Chemical Industry Co., Ltd.) with an average particle diameter of 200 nm, as a nonionic surfactant The ethylene oxide adduct of 4,7-dihydroxy-2,4,7,9-tetramethyl-5-decyne (“Surfynol 465” manufactured by Nissin Chemical Industry Co., Ltd.) and water were obtained as untreated A liquid water-based resin with a solid content concentration of 5% of the urethane resin in a cured state. Here, the addition amount of the nonionic surfactant is an amount of 100 ppm with respect to the obtained aqueous resin.

(Manufacture of multilayer films)

A pellet of an alicyclic olefin resin (“ZEONOR” manufactured by Zeon Corporation; glass transition temperature of 135° C.) was dried at 70° C. for 2 hours using a hot air dryer through which air was circulated. Then, using a T-die type film melt extrusion molding machine equipped with a resin melt-kneader (with a screw having a diameter of 65 mm), a thickness of the film was produced under the molding conditions of the molten resin temperature of 270° C. and the width of the T-die of 500 mm. 100μm, 1000m long base film. The base film is a base film formed of an alicyclic olefin resin.

Discharge treatment was performed on one side of the base film using a corona treatment apparatus. The above-mentioned liquid water-based resin was applied to the surface of the base film to which the discharge treatment was performed using a roll coater so that the dry thickness was 50 nm to form a film of the water-based resin. Then, the film was heated at a temperature of 100° C. for 60 seconds to cure and dry the film of the aqueous resin, thereby forming a resin layer on the base film. Thus, a multilayer film including a base film and a resin layer was obtained. The thickness of the resin layer of the obtained multilayer film was measured with a film thickness meter ("FE-300" manufactured by Otsuka Electronics Co., Ltd.), and it was 50 nm.

The obtained multilayer film was evaluated by the above-mentioned method.

[Examples 2, 3 and Comparative Examples 1 to 4]

When producing the water-based resin, the amount of glycerol polyglycidyl ether as an epoxy compound, the amount of silica particles having an average particle diameter of 40 nm, and the amount of silica particles having an average particle diameter of 200 nm were changed as follows shown in Table 1.

The production and evaluation of the multilayer film were carried out as in Example 1 except for the above.

[result]

The results of Examples and Comparative Examples are shown in the following table. In the table below, the abbreviations have the following meanings.

The amount of large particles: the amount of silica particles having an average particle diameter of 200 nm.

The amount of small particles: the amount of silica particles having an average particle diameter of 40 nm.

Epoxy amount: the amount of glycerol polyglycidyl ether.

[Table 1]

[Table 1. Results of Examples and Comparative Examples]

[inspection]

From the results of the Examples and Comparative Examples, it was confirmed that in the multilayer film including the base film and the resin layer in combination, the protrusions formed on the surface of the resin layer opposite to the base film satisfy 3.5≤G≤7, In addition, when N _B ≥ N _C ≥ N _D ≥ N _E ≥ N _F , when it is wound up to form a film roll, the occurrence of convex defects can be suppressed, and the internal haze can be reduced.

Claims (7)

1. A multilayer film comprising: substrate film, and The particle-containing resin layer provided on the base film, in, The resin layer has a plurality of protrusions on the surface opposite to the base film, Among the protrusions, (a) the number of protrusions with a height of 5 nm per 1 mm ² is set as N _A pieces/mm ² , and (b) the number of protrusions with a height of 10 nm per 1 mm ² is set as N _B pieces/ mm ² , (c) the number of protrusions with a height of 15 nm per 1 mm ² is set as N _C /mm ² , (d) the number of protrusions with a height of 20 nm per 1 mm ² is set as N _D /mm ² , ( e) When the number of protrusions with a height of 25 nm per 1 mm ² is set as NE/mm ² , and ( _f ) the number of protrusions with a height of 30 nm per 1 mm ² is set as NF _/ mm ² , The value G expressed by G=N _A /NF is _3.5≤G≤7 , And, N _B ≥ N _C ≥ N _D ≥ N _E ≥ N _F , The particles include: particles S having an average particle diameter of less than 150 nm, and particles L having an average particle diameter of 150 nm or more, The resin layer has a thickness of 10 nm or more and 100 nm or less, the resin layer comprises a polymer, The amount of the particles S in the resin layer is 2 parts by weight or more and 24 parts by weight or less with respect to 100 parts by weight of the polymer, The amount of the particles L in the resin layer is 5 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the polymer, The difference between the average particle diameter of the particles S and the average particle diameter of the particles L is 120 nm or more and 160 nm or less, The difference between the amount of the particles L and the amount of the particles S is 0.5 parts by weight or more and 25 parts by weight or less with respect to 100 parts by weight of the polymer. 2. The multilayer film of claim 1, wherein the polymer comprises polyurethane. 3 . The multilayer film according to claim 1 , wherein the average particle diameter of the particles L is twice or more the thickness of the resin layer. 4 . 4. The multilayer film according to any one of claims 1 to 3, wherein the particles are silica. 5. The multilayer film of claim 4, wherein the multilayer film is a retardation film. 6. The multilayer film of claim 4, wherein the multilayer film is a polarizer protective film. 7. A method for producing a multilayer film, which is the method for producing a multilayer film according to any one of claims 1 to 6, Wherein, the manufacturing method includes: The process of mixing a polymer and a plurality of particles with different average particle diameters to obtain a fluid resin; a step of applying the resin in a fluid state on a base film to form a film of the resin; and A step of curing and/or drying the resin film formed on the base film to obtain a resin layer.