JP7632540B2 - Hard coat film and curable composition - Google Patents

Description

The present invention relates to a hard coat film and a curable composition that have excellent anti-Newton ring properties, excellent transparency, and reduced glare.

Plastic products, for example, resin substrates such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, styrene-based resins such as ABS, MS resin, and AS resin, vinyl chloride-based resins, and cellulose acetate such as triacetyl cellulose, are particularly excellent in terms of their light weight, ease of processing, and impact resistance, and are therefore used in a variety of applications, including as containers, instrument panels, packaging materials, various housing materials, optical disc substrates, plastic lenses, and substrates for display devices such as liquid crystal displays and plasma displays.

These plastic products have low surface hardness and are easily scratched, and in the case of transparent resins such as polycarbonate and polyethylene terephthalate, the inherent transparency or appearance of the resin is significantly impaired, making it difficult to use plastic products in fields that require abrasion resistance. For this reason, active energy ray-curable hard coat materials (coating materials) are used to impart abrasion resistance to the surface of these plastic products.

In recent years, transparent resin films coated with a hard coat have come to be widely used in image display devices such as touch panels. In such touch panels, particularly resistive touch panels, there is a problem in that when an input is made by pressing the upper electrode film and the lower electrode substrate come close to each other, causing interference of reflected light and resulting in the generation of optical patterns known as Newton rings.

A typical method for preventing such Newton rings is known to suppress the interference of reflected light by providing irregularities on the surface of the upper electrode. For example, in Patent Document 1, silica particles are blended to form the irregularities. In Patent Document 2, organic fine particles are blended to form the irregularities. Meanwhile, in Patent Document 3, the irregularities are formed by phase separation between a multifunctional acrylate with different compatibility and an acrylic polymer with a small solubility parameter.

JP 2002-373056 A JP 2003-191393 A JP 2009-123685 A

In the above Patent Document 1, the high hardness of the silica particles may damage the lower electrode, resulting in reduced durability. In contrast, in the above Patent Document 2, although the organic fine particles prevent the lower electrode from being damaged, there is a problem in that the particles may detach and the anti-Newton ring properties may be reduced. Furthermore, in the above Patent Document 3, the viscosity adjustment range of the multifunctional acrylate is narrow, making it difficult to achieve sufficiently good transparency.

The present invention aims to solve the various problems mentioned above. That is, the object of the present invention is to provide a hard coat film that has excellent anti-Newton ring properties and transparency and reduces glare, and a curable composition therefor.

The present inventors conducted intensive research to solve the above problems, and as a result, discovered that the above problems can be solved by a hard coat film having a surface unevenness structure obtained by curing a curable composition containing a polymer (A) containing a specific high SP value amide group and an unsaturated double bond, a specific low SP value polymer (B) and a polyfunctional (meth)acrylate (C) in a specified ratio, in which the recesses are composed of domains derived from the polymer (A) and the protrusions are composed of domains containing the polymer (B) and derived from the polyfunctional (meth)acrylate (C). That is, the present invention is as follows.

[1] A hard coat film having an uneven surface structure, the recesses being composed of domains derived from a polymer (A) containing an amide group and an unsaturated double bond and having a solubility parameter (SP value) of 16 to 20, and the protrusions being composed of domains derived from a polymer (B) containing a solubility parameter (SP value) of 10 to 15 and a multifunctional (meth)acrylate (C) having an SP value of 10 to 15.

[2] The hard coat film described in [1], which has a surface roughness (Ra) of 0.05 to 1.5 μm as measured by a white light interference microscope.

[3] The hard coat film according to [1] or [2], which is a cured product of a curable composition containing a polymer (A), a polymer (B), and a polyfunctional (meth)acrylate (C), in which the ratio of [the weight of the polymer (A)]:[the total weight of the polymer (B) and the polyfunctional (meth)acrylate (C)] is 10:90 to 80:20.

[4] The hard coat film according to [3], in which the ratio of the polymer (B) weight to the polyfunctional (meth)acrylate (C) weight in the curable composition is 5:95 to 40:60.

[5] The hard coat film according to any one of [1] to [4], wherein the viscosity of polymer (A) measured at 25°C and at a concentration of 30% by weight in propylene glycol monomethyl ether is 100 to 4,000 mPa·s.

[6] The hard coat film according to any one of [1] to [5], wherein the amount of unsaturated double bonds in the polymer (A) is 1.00 to 10.00 mmol/g.

[7] The hard coat film according to any one of [1] to [6], wherein the polymer (A) has a (meth)acryloyl group.

[8] The hard coat film according to any one of [1] to [7], wherein the polymer (B) is a (meth)acrylic polymer.

[9] The hard coat film according to any one of [1] to [8], wherein the polymer (A) has a structural unit derived from a (meth)acrylamide monomer.

（式（１）中、Ｒは重合体（Ａ）の主鎖部分を表し、Ｒ^１は水素原子またはメチル基を表す。） [10] The hard coat film according to any one of [1] to [9], wherein the polymer (A) has a side chain of a structural unit represented by the following formula (1):

(In formula (1), R represents the main chain portion of the polymer (A), and ^R1 represents a hydrogen atom or a methyl group.)

[11] A hard coat film according to any one of [1] to [10], having a thickness of 1 to 10 μm.

[12] A curable composition comprising a polymer (A) having a solubility parameter (SP value) of 16 to 20, which contains an amide group and an unsaturated double bond, a polymer (B) having a solubility parameter (SP value) of 10 to 15, and a polyfunctional (meth)acrylate (C) having an SP value of 10 to 15, and in which the ratio of [weight of polymer (A)]:[total weight of polymer (B) and weight of polyfunctional (meth)acrylate (C)] is 10:90 to 80:20.

[13] The curable composition according to [12], in which the ratio of [weight of polymer (B)] to [weight of multifunctional (meth)acrylate (C)] is 5:95 to 40:60.

[14] The curable composition according to [12] or [13], wherein the viscosity of the polymer (A) measured at 25°C and at a concentration of 30% by weight in propylene glycol monomethyl ether is 100 to 4,000 mPa·s.

[15] The curable composition according to any one of [12] to [14], wherein the amount of unsaturated double bonds in the polymer (A) is 1.00 to 10.00 mmol/g.

[16] The curable composition according to any one of [12] to [15], wherein the polymer (A) has a (meth)acryloyl group.

[17] The curable composition according to any one of [12] to [16], wherein the polymer (B) is a (meth)acrylic polymer.

[18] The curable composition according to any one of [12] to [17], wherein the polymer (A) has a structural unit derived from a (meth)acrylamide monomer.

（式（１）中、Ｒは重合体（Ａ）の主鎖部分を表し、Ｒ^１は水素原子またはメチル基を表す。） [19] The curable composition according to any one of [12] to [18], wherein the polymer (A) has a side chain of a structural unit represented by the following formula (1):

(In formula (1), R represents the main chain portion of the polymer (A), and ^R1 represents a hydrogen atom or a methyl group.)

The present invention provides a hard coat film that has excellent anti-Newton ring properties, transparency, and reduced glare.

FIG. 2 is a diagram showing the results of Raman mapping of the hard coat film formed in Example 1.

The present invention will be described in detail below, but the following description is merely an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not exceed the gist of the invention. The present invention can be modified and implemented as desired without departing from the gist of the invention.

In the present invention, "(meth)acrylate" is a general term for acrylate and methacrylate, and means either one or both. Similarly, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, and means either one or both, and "(meth)acryloyl group" is a general term for acryloyl group and methacryloyl group, and means either one or both. The same applies to "(meth)acrylamide-based monomer".
In the present invention, the weight average molecular weight (Mw) of the polymers (A) and (B) can be determined as a polystyrene-converted value by gel permeation chromatography (GPC). A specific method for measuring the weight average molecular weight will be described in the Examples section below.
The viscosity of the polymer (A) and the polymer (B) can be measured using an E-type viscometer under the following measurement conditions, but for commercially available products, catalog values can be used.
<Viscosity measurement conditions>
Solid content: 30% by weight
Temperature: 25°C
Equipment: TOKIMEC E-type viscometer TV-20

The hard coat film of the present invention is a hard coat film having an uneven structure on the surface, in which the recesses are composed of domains derived from a polymer (A) containing an amide group and an unsaturated double bond and having a solubility parameter (SP value) of 16 to 20, and the protrusions are composed of domains containing a polymer (B) having a solubility parameter (SP value) of 10 to 15 and derived from a multifunctional acrylate (C) having an SP value of 10 to 15.
As described above, the hard coat film of the present invention has recesses and protrusions each composed of a specific domain, and the composition of each domain can be confirmed, for example, by microscopic Raman spectroscopy, as shown in the examples described later.

[Reasons why the present invention is effective]
The hard coat film of the present invention has excellent anti-Newton ring properties, transparency, etc., and further has the effect of reducing glare. The reason why the hard coat film of the present invention has such effects is not clear, but is presumed to be due to the following reasons.

First, the curable composition of the present invention, which will be described later, contains polymer (A), polymer (B) and polyfunctional (meth)acrylate (C). Since each of these components has a specific solubility parameter (SP value), when the curable composition is applied to a substrate and irradiated with ultraviolet light or the like, phase separation occurs prior to the curing reaction into polymer (A) with a higher SP value and polymer (B) and polyfunctional (meth)acrylate (C) with a lower SP value. As the curing reaction progresses, a recessed portion composed of a domain derived from polymer (A) and a protruding portion composed of a domain containing polymer (B) and derived from polyfunctional (meth)acrylate (C) are formed.

Newton rings are interference fringes that occur when the surface of a hard coat film is pressed with a finger or the like, due to interference between the light reflected from the hard coat film surface and the light reflected from the substrate surface. However, because the hard coat film of the present invention has an uneven structure as described above, it is believed that interference between the light reflected from the hard coat film surface and the light reflected from the substrate surface is suppressed, thereby suppressing the occurrence of Newton rings (obtaining anti-Newton ring properties).

In high-definition display devices with fine pixel sizes, glare is a problem when the size of conventional surface irregularities leads to reduced image quality, such as glare on the screen and blurred text. In other words, in the case of high-definition display devices, the size of conventional surface irregularities is close to the order of the pixel size of high-definition displays, and glare occurs due to the lens effect of the surface irregularities. Details will be described later, but the hard coat film of the present invention is thought to be able to reduce glare because the shape of the surface irregularities is controlled so that it is not spherical as in the past.

The hard coat film of the present invention can also have excellent transparency (light transmittance, haze) because the refractive index of the domains derived from the polymer (A) constituting the recesses is close to the refractive index of the domains derived from the polymer (B) and the polyfunctional (meth)acrylate (C) constituting the protrusions.

[SP value]
The solubility parameter (SP value) is a measure of solubility. The larger the SP value, the higher the polarity, and conversely, the smaller the SP value, the lower the polarity. In the present invention, the SP value is a value actually measured by the following method.
0.5 g of sample is weighed into a 100 ml Erlenmeyer flask, and 10 ml of acetone is added to dissolve the resin. While stirring with a magnetic stirrer, hexane is added dropwise to obtain the amount of hexane added (vh) at the point where the solution becomes turbid (cloudy point). Next, the amount of deionized water added (vd) at the cloudy point when deionized water is used instead of hexane is obtained. From vh and vd, the SP value can be obtained using the formula given in the reference: SUH, CLARKE, J. P. S. A-1, 5, 1671-1681 (1967). In addition, when the solubility parameter cannot be obtained by the above method, such as when the sample is not dissolved in acetone, it is estimated by the method proposed by Fedors et al. Specifically, it can be determined by referring to "POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (pp. 147-154)".

[Curable composition]
Specifically, the hard coat film of the present invention can be produced by curing the curable composition of the present invention, which contains the above-mentioned polymer (A), polymer (B), and polyfunctional (meth)acrylate (C), and in which the ratio of [weight of polymer (A)]:[total weight of polymer (B) and polyfunctional (meth)acrylate (C)] is 10:90 to 80:20.

In addition, in the curable composition of the present invention, the ratio of [weight of polymer (A)] to [total weight of polymer (B) and polyfunctional (meth)acrylate (C)] is preferably 12:88 to 60:40, more preferably 14:86 to 45 to 55, particularly preferably 16:84 to 40:60, and most preferably 20:80 to 35:65. When the blending amounts of polymer (A), polymer (B), and polyfunctional (meth)acrylate (C) are within the above ranges, it is preferable from the viewpoint of improving anti-Newton ring properties, transparency, glare, and the like. Furthermore, from the viewpoint of further improving these effects, the ratio of [weight of polymer (B)] to [weight of polyfunctional (meth)acrylate (C)] is preferably 5:95 to 40:60, more preferably 10:90 to 35:65, and most preferably 20:80 to 30:70.

The hard coat film of the present invention will be described in detail below according to the method for producing the hard coat film of the present invention by curing the curable composition of the present invention, but the method for producing the hard coat film of the present invention is not limited to the following method.

<Polymer (A)>
The polymer (A) has an SP value of 16 to 20 and contains an amide group and an unsaturated double bond.

When the curable composition is cured, in order to form domains of recesses and domains of protrusions, the polymer (A) undergoes phase separation between the polymer (B) and the functional (meth)acrylate (C), so that the SP value of the polymer (A) must be at least 16. When the SP value of the polymer (A) is at most 20, the curable composition has good coatability and good anti-Newton ring properties.
The SP value of the polymer (A) is particularly preferably from 17 to 19.8, more preferably from 17.5 to 19.6, and most preferably from 18 to 19.4.

The polymer (A) is not particularly limited as long as it contains an amide group and an unsaturated double bond, but it is preferable for the polymer (A) to have a (meth)acryloyl group from the viewpoint of UV curability, and it is also preferable for the polymer (A) to have an amide group from the viewpoint of improving glare. Furthermore, it is preferable from the viewpoint of improving the SP value that the amide group is contained in the polymer (A) as a structural unit derived from a (meth)acrylamide monomer.

In addition, from the viewpoints of transparency and UV curability, it is preferable that polymer (A) has a side chain of a structural unit represented by the following formula (1).

（式（１）中、Ｒは重合体（Ａ）の主鎖部分を表し、Ｒ^１は水素原子またはメチル基を
表す。）

(In formula (1), R represents the main chain portion of the polymer (A), and ^R1 represents a hydrogen atom or a methyl group.)

Such a polymer (A) can be obtained, for example, by reacting acrylic acid with the glycidyl group portion of the structural unit derived from glycidyl methacrylate in a copolymer of a (meth)acrylamide monomer, which is a (meth)acrylic monomer having an amide group, and glycidyl methacrylate. By appropriately adjusting the components of the (meth)acrylamide monomer and glycidyl methacrylate, a polymer (A) having an SP value in the above range can be obtained.

Examples of the (meth)acrylamide monomer used in the production of the polymer (A) include acryloylmorpholine, hydroxylmethylacrylamide, hydroxylethylacrylamide, dimethylacrylamide, diethylacrylamide, and N-isopropylacrylamide.
In producing the polymer (A), these may be used alone or in combination of two or more.

The copolymerization ratio of the (meth)acrylamide monomer and glycidyl methacrylate is preferably (meth)acrylamide monomer:glycidyl methacrylate=10-90:90-10 by weight, more preferably 75-25:75-25, and particularly preferably 60-40:60-40. When the copolymerization ratio of the (meth)acrylamide monomer and glycidyl methacrylate is within the above range, the SP value and refractive index of the polymer (A) become appropriate values, which is preferable.

It is preferable to use 10 to 50 parts by weight, more preferably 15 to 40 parts by weight, and especially 20 to 30 parts by weight, of acrylic acid per 100 parts by weight of the total of the (meth)acrylamide monomer and glycidyl methacrylate. By using acrylic acid within the above range, double bonds can be effectively introduced into the polymer side chain of polymer (A), transparency is improved, and it is preferable from the viewpoint of UV curability.

Polymer (A) can be produced, for example, as follows using the above-mentioned (meth)acrylamide monomer, glycidyl methacrylate, and acrylic acid.

Propylene glycol monomethyl ether is added to a separable flask equipped with a thermometer, a stirrer, a reflux condenser, etc.
Meanwhile, in a measuring cylinder or the like, glycidyl methacrylate, a (meth)acrylamide monomer such as acryloylmorpholine, propylene glycol monomethyl ether, and 2,2'-azobis(2,4-dimethylvaleronitrile) are added to prepare a monomer solution.
Thereafter, the stirrer in the separable flask is started, and then nitrogen gas is introduced into the separable flask and the measuring cylinder.

Next, the separable flask is immersed in an oil bath and heated to an internal temperature of approximately 65°C. The monomer solution prepared in the measuring cylinder is then pumped into the separable flask using a pump or similar device, and added dropwise to carry out radical polymerization. After the addition is complete, stirring is continued for approximately 2 hours at an internal temperature of approximately 65°C, after which 2,2'-azobis(2,4-dimethylvaleronitrile) is added and reacted for approximately 3 hours, after which 258.8 g of propylene glycol monomethyl ether and p-methoxyphenol are added and the mixture is heated to approximately 100°C.

Next, acrylic acid and triphenylphosphine are added and reacted at about 110°C for about 6 hours to obtain polymer (A) having an amide group and an unsaturated double bond.

The weight average molecular weight (Mw) of the polymer (A) thus obtained is preferably 5,000 to 100,000, more preferably 10,000 to 80,000, particularly preferably 15,000 to 50,000, and most preferably 20,000 to 40,000. If the weight average molecular weight (Mw) of the polymer (A) is equal to or greater than the lower limit, the fluidity of the components forming the domains in the coating film during drying is appropriately reduced, making it possible to adjust the magnitude of phase separation to an appropriate level for suppressing glare, and if it is equal to or less than the upper limit, the fluidity of the components forming the domains in the coating film during drying is appropriately maintained, resulting in good anti-Newton ring properties without impeding the progress of phase separation.

The viscosity of polymer (A) measured at 25°C and a concentration of 30% by weight in propylene glycol monomethyl ether is preferably 100 to 4,000 mPa·s, more preferably 500 to 3000 mPa·s, and most preferably 800 to 2000 mPa·s. If the viscosity of polymer (A) is equal to or higher than the lower limit, the fluidity of the components forming the domains in the coating film during drying is appropriately reduced, making it possible to adjust the magnitude of phase separation to an appropriate level for suppressing glare. If the viscosity is equal to or lower than the upper limit, the fluidity of the components forming the domains in the coating film during drying is appropriately maintained, and the anti-Newton ring properties are good without impeding the progress of phase separation. The viscosity of polymer (A) can be adjusted by appropriately adjusting the molecular weight.

The amount of unsaturated double bonds in polymer (A) is preferably 1.00 to 10.00 mmol/g, more preferably 1.5 to 4.5 mmol/g, and most preferably 2 to 4 mmol/g. If the amount of unsaturated double bonds in polymer (A) is equal to or greater than the lower limit, the transparency (total light transmittance) and curability of the cured film are good, and if it is equal to or less than the upper limit, the anti-Newton ring properties of the cured film are good.

The curable composition of the present invention may contain only one type of polymer (A), or may contain two or more types of polymers having different monomer compositions, physical properties, etc.

<Polymer (B)>
The polymer (B) has an SP value of 10 to 15.

When the SP value of the polymer (B) is 10 or more, the choice of solvents in which the polymer can be dissolved is broadened, and when the SP value is 15 or less, phase separation from the polymer (A) is easily caused, improving the anti-Newton ring property.
The SP value of polymer (B) is particularly preferably 11 to 14.5, and more preferably 12 to 14. The difference between the SP value of polymer (B) and the SP value of polymer (A) is preferably about 1 to 9, more preferably about 3 to 8, and most preferably about 4 to 7. If the difference is within this range, phase separation is likely to occur, and the anti-Newton ring properties are improved, as described above.

There are no particular limitations on the polymer (B), but a (meth)acrylic polymer is preferred.

In the present invention, the term "(meth)acrylic polymer" refers to a polymer synthesized from a raw material containing (meth)acrylic acid and/or a (meth)acrylic acid derivative, and is used to include a polymer obtained by further modifying this polymer. As long as the polymer uses at least one raw material ((meth)acrylate monomer) containing (meth)acrylic acid or a (meth)acrylic acid derivative, there is no particular limitation on the other raw materials. For example, the polymer may be a copolymer using a known polymerizable monomer such as a hydrocarbon monomer having a vinyl group other than a (meth)acrylate monomer. In addition, the term "(meth)acrylic acid derivative" refers to a compound having a structure similar to that of (meth)acrylic acid, such as a metal salt of (meth)acrylic acid, a (meth)acrylic acid ester, or an (meth)acrylic acid amide.

Examples of raw material monomers for producing a (meth)acrylic polymer include acrylic acid, methacrylic acid, and alkyl (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, stearyl (meth)acrylate, phenoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate;
(meth)acrylate monomers having an oxirane structure, such as glycidyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate;
(meth)acrylate monomers having a fluoroalkyl group, such as perfluorohexylethyl (meth)acrylate, 1H,1H,7H-dodecafluoroheptyl (meth)acrylate, and 1H,1H,9H-hexadecafluorononyl (meth)acrylate;
(meth)acrylate monomers having an amino group, such as N,N-diethylaminoethyl (meth)acrylate and N,N-dimethylaminoethyl (meth)acrylate;
(meth)acrylate monomers having a hydroxyl group, such as 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 1,6-hexanediol mono(meth)acrylate;
Furthermore, examples of raw materials other than the (meth)acrylic acid derivatives include hydrocarbon monomers having a vinyl group, such as styrene, p-chlorostyrene, p-methoxystyrene, divinylbenzene, N-vinylpyrrolidone, N-vinylcaprolactam, acrylonitrile, ethylene glycol divinyl ether, pentaerythritol divinyl ether, 1,6-hexanediol divinyl ether, trimethylolpropane divinyl ether, ethylene oxide-modified hydroquinone divinyl ether, ethylene oxide-modified bisphenol A divinyl ether, pentaerythritol trivinyl ether, dipentaerythritol hexavinyl ether, and ditrimethylolpropane polyvinyl ether.

These may be used alone or in combination of two or more.

Among these, alkyl (meth)acrylates such as methyl (meth)acrylate and ethyl (meth)acrylate are preferred.
By appropriately adjusting the composition of the raw material monomers used in the production of the polymer (B), the SP value of the polymer (B) can be adjusted to fall within the above range.

Polymer (B) can be produced by a conventional method, for example, a radical polymerization reaction in which raw material monomers are polymerized in an organic solvent in the presence of a radical polymerization initiator.

The weight average molecular weight (Mw) of the polymer (B) thus obtained is preferably 50,000 to 500,000, more preferably 60,000 to 300,000, even more preferably 65,000 to 200,000, particularly preferably 70,000 to 100,000, and most preferably 75,000 to 90,000. If the weight average molecular weight (Mw) of the polymer (B) is equal to or greater than the lower limit, the fluidity of the components forming the domains in the coating film during drying is appropriately reduced, making it possible to adjust the magnitude of phase separation to an appropriate level for suppressing glare. If the weight average molecular weight (Mw) of the polymer (B) is equal to or less than the upper limit, the fluidity of the components forming the domains in the coating film during drying is appropriately maintained, and the anti-Newton ring properties are improved without impeding the progress of phase separation.

The viscosity of polymer (B) measured at 25°C in methyl ethyl ketone at a concentration of 30% by weight is preferably 400 to 2500 mPa·s, more preferably 600 to 2200 mPa·s, and most preferably 800 to 2000 mPa·s. If the viscosity of polymer (B) is equal to or higher than the lower limit, the fluidity of the components forming the domains in the coating film during drying is appropriately reduced, making it possible to adjust the magnitude of phase separation to an appropriate level for suppressing glare. If the viscosity is equal to or lower than the upper limit, the fluidity of the components forming the domains in the coating film during drying is appropriately maintained, resulting in good anti-Newton ring properties without impeding the progress of phase separation. The viscosity of polymer (B) can be adjusted by appropriately adjusting the molecular weight.

The curable composition of the present invention may contain only one type of polymer (B), or may contain two or more types of polymers having different monomer compositions, physical properties, etc.

<Polyfunctional (meth)acrylate (C)>
The polyfunctional (meth)acrylate (C) is a compound having a (meth)acryloyl group and having two or more unsaturated double bonds in one molecule. Examples of such polyfunctional (meth)acrylates include polyfunctional (meth)acrylates having two or more unsaturated double bonds in one molecule, which are dealcoholization products of polyhydric alcohols and (meth)acrylates.

In the present invention, the polyfunctional (meth)acrylate (C) has an SP value of 10 to 15. When the SP value of the polyfunctional (meth)acrylate (C) is 10 or more, the choice of solvents in which it can be dissolved is broadened, and when the SP value is 15 or less, phase separation with the polymer (A) occurs easily, improving the anti-Newton ring properties. The SP value of the polyfunctional (meth)acrylate (C) is particularly preferably 11 to 14.5, more preferably 12 to 14. The difference from the SP value of the polymer (A) is preferably about 1 to 9, more preferably about 3 to 8, and most preferably about 4 to 7. If the difference is within this range, phase separation occurs easily, as described above, improving the anti-Newton ring properties.

Among the polyfunctional (meth)acrylates, from the viewpoint of obtaining a good hardness of the hard coat film and good curability of the curable composition, it is preferable to use a polyfunctional (meth)acrylate having three or more (meth)acryloyl groups in one molecule. Specific examples include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate (the SP value of a mixture of pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate is 12.6), dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate (the SP value of a mixture of dipentaerythritol hexa(meth)acrylate and dipentaerythritol penta(meth)acrylate is 12.4), trimethylolpropane tri(meth)acrylate, etc. Among these, from the viewpoint of obtaining a good hardness of the hard coat film and good curability of the curable composition, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and dipentaerythritol penta(meth)acrylate are preferred, and dipentaerythritol hexa(meth)acrylate is particularly preferred.

The curable composition of the present invention may contain only one type of these polyfunctional (meth)acrylates (C), or may contain two or more types.

<Compound (D)>
The hard coat film of the present invention is preferable because it has a domain derived from a compound (D) having 10 or more carbon atoms and one or more double bonds, and can improve the wet heat resistance. Therefore, similarly, the curable composition of the present invention preferably contains a compound (D) having 10 or more carbon atoms and one or more double bonds. More specifically, the compound (D) is preferably an acrylate having a dimer acid skeleton.

The lower limit of the number of carbon atoms in compound (D) is 10 or more, and from the viewpoint of water resistance, 14 or more is preferable, 18 or more is more preferable, and 20 or more is particularly preferable. The upper limit is preferably 70 or less, more preferably 65 or less, and particularly preferably 60 or less, from the viewpoint of crosslinkability and compatibility.

The lower limit of the number of double bonds in compound (D) is 1 or more, preferably 2 or more, and from the viewpoint of water resistance, the upper limit is preferably 5 or less, more preferably 4 or less, and particularly preferably 3 or less.

Specific examples of compound (D) include TA37198 and Teslac manufactured by Hitachi Chemical.

The content of compound (D) in the curable composition of the present invention is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and most preferably 1 to 10 parts by weight, in terms of moisture resistance and moist heat resistance, when the total amount of polymer (A), polymer (B), and polyfunctional (meth)acrylate (C) is taken as 100 parts by weight.

<Polymerization initiator>
The curable composition of the present invention preferably contains a polymerization initiator in order to cure it by active energy rays. The polymerization initiator can be added in an amount of usually 0.01 parts by weight or more, preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and usually 20 parts by weight or less, preferably 10 parts by weight or less, based on 100 parts by weight in total of the polymer (A), the polymer (B), the polyfunctional (meth)acrylate (C), and the compound (D) used as needed in the curable composition of the present invention.

As the polymerization initiator, a photopolymerization initiator is preferable, and examples thereof include 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1. These polymerization initiators may be used alone or in combination of two or more.

<Inorganic particles>
The curable composition of the present invention may further contain inorganic particles having an average primary particle diameter of 1 μm or less. By containing such inorganic particles, it is possible to provide a hard coat film having good anti-blocking properties while maintaining high hardness.

In other words, by containing the aforementioned high SP value polymer (A), the low SP value polymer (B), and the polyfunctional (meth)acrylate (C), phase separation can be achieved, and by adding inorganic particles as well, when cured, the inorganic particles will be present near the surface along with the phase-separated resin. The presence of these resins and inorganic particles can form appropriate irregularities on the surface of the hard coat film, allowing it to exhibit excellent anti-blocking properties.

Examples of inorganic particles include silica (including organosilica sol), alumina, titania, zeolite, mica, synthetic mica, calcium oxide, zirconium oxide, zinc oxide, magnesium fluoride, smectite, synthetic smectite, vermiculite, ITO (indium oxide/tin oxide), ATO (antimony oxide/tin oxide), tin oxide, indium oxide, and antimony oxide, with silica being preferred. The inorganic particles listed above may be used alone or in combination of two or more.

The average primary particle size of the inorganic particles is 1 μm or less, preferably 200 nm or less, and more preferably 100 nm or less. The lower limit of the average primary particle size of the inorganic particles is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more. If inorganic particles with an average primary particle size of more than 1 μm are used, sedimentation may occur due to the particle's own weight, and the storage stability of the coating liquid of the curable composition may decrease.

On the other hand, the movement of inorganic particles having an average primary particle size within the above range in the coating liquid of the curable composition is dominated by thermal diffusion rather than settling due to gravity, so the inorganic particles can be stably dispersed in the coating liquid of the curable composition, and when a hard coat film is formed, they are effectively present on the surface. In addition, the smaller the average primary particle size of the inorganic particles, the better the optical properties tend to be.

The average primary particle size of the inorganic particles refers to the average particle size observed, for example, with an electron microscope such as a TEM.

The above inorganic particles may be blended in the curable composition of the present invention as inorganic particles surface-modified with polymer (A) in order to improve anti-blocking properties and hardness. To produce inorganic particles surface-modified with polymer (A), for example, a method can be used in which polymer (A) and inorganic particles are reacted in the presence of an acid, a base, or a silane coupling reaction catalyst such as aluminum acetylacetonate at 25 to 120°C for about 1 to 24 hours.

<Other ingredients>
The curable composition of the present invention may contain other components in addition to the above-mentioned polymer (A), polymer (B), polyfunctional (meth)acrylate (C), compound (D), polymerization initiator and inorganic particles, within the scope of not impairing the effects of the present invention. Examples of other components that the curable composition of the present invention may contain include a solvent for uniformly mixing each component, and various commonly used additives such as an antistatic agent, a plasticizer, a surfactant, an antioxidant and an ultraviolet absorber.

The solvent is not particularly limited, and is selected appropriately taking into consideration the polymer (A), polymer (B), polyfunctional (meth)acrylate (C), compound (D) used as needed, the material of the base material, the method of applying the composition, etc. Specific examples of solvents that can be used include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone; ether solvents such as diethyl ether, isopropyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, anisole, and phenetole; ester solvents such as ethyl acetate, butyl acetate, isopropyl acetate, and ethylene glycol diacetate; amide solvents such as dimethylformamide, diethylformamide, and N-methylpyrrolidone; cellosolve solvents such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol; and halogen-based solvents such as dichloromethane and chloroform.

These solvents may be used alone or in combination of two or more. Of these solvents, ester-based solvents, ether-based solvents, alcohol-based solvents, and ketone-based solvents are preferably used.

There is no particular limit to the amount of solvent used, and it is appropriately determined taking into consideration the coatability of the prepared curable composition, the viscosity and surface tension of the liquid, the compatibility of the solids, etc. Usually, the curable composition of the present invention is prepared using the above-mentioned solvent as a coating liquid having a solids concentration of 20 to 100% by weight, particularly 30 to 80% by weight. Here, the solids in the curable composition of the present invention refer to the total of the components other than the solvent contained in the curable composition of the present invention.

<Method of preparing curable composition>
A method for preparing the curable composition of the present invention is not particularly limited, and the composition can be prepared, for example, by mixing the polymer (A), the polymer (B), the polyfunctional (meth)acrylate (C), and, if necessary, the compound (D), a solvent, a polymerization initiator, an additive, and the like.

[Hard coat film/laminate]
The hard coat film of the present invention is obtained by curing the above-mentioned curable composition of the present invention. That is, the hard coat film of the present invention can be obtained by applying the curable composition of the present invention onto a substrate or the like and curing it into a film. In addition, the hard coat film of the present invention can be obtained by applying the curable composition of the present invention onto another resin film as a substrate and curing it to form the hard coat film of the present invention, thereby obtaining a film laminate in which the hard coat film of the present invention is laminated onto the other resin film.

As the substrate for forming the hard coat film, various resin films and resin plates can be used. As the resin film, for example, triacetyl cellulose (TAC) film, polyethylene terephthalate (PET) film, diacetylene cellulose film, acetate butyrate cellulose film, polyethersulfone film, polyacrylic resin film, polyurethane resin film, polyester film, polycarbonate film, polysulfone film, polyether film, polymethylpentene film, polyetherketone film, (meth)acrylonitrile film, cycloolefin polymer (COP) film, etc. can be used. In addition, as the resin plate, for example, acrylic plate, triacetyl cellulose plate, polyethylene terephthalate plate, diacetylene cellulose plate, acetate butyrate cellulose plate, polyethersulfone plate, polyurethane plate, polyester plate, polycarbonate plate, polysulfone plate, polyether plate, polymethylpentene plate, polyetherketone plate, (meth)acrylonitrile plate, etc. can be mentioned. In addition, glass, etc. can be used as necessary. All of these substrates have excellent transparency and are also preferable for application to the display device described later. The thickness of the substrate can be selected appropriately depending on the application, but typically is around 25 to 1000 μm.

The method for applying the curable composition of the present invention is not particularly limited. For example, the composition can be applied by a dip coating method, an air knife coating method, a curtain coating method, a spin coating method, a roller coating method, a bar coating method, a wire bar coating method, a gravure coating method, an extrusion coating method (U.S. Pat. No. 2,681,294), or the like.

The thickness of the hard coat film of the present invention is not particularly limited and can be set appropriately taking into consideration various factors, but it is preferably in the range of 1 to 10 μm, particularly 3 to 8 μm, and most preferably 4 to 7 μm.

The coating film applied and formed on the substrate may be phase-separated at room temperature, or the composition may be dried before curing to cause phase separation in advance. When the applied coating film is dried or heated before curing, it is preferably dried at 30 to 200°C, more preferably 40 to 150°C, for preferably 0.01 to 30 minutes, more preferably 0.1 to 10 minutes, to cause phase separation in advance between the components constituting the concaves and convex parts of the surface unevenness structure of the hard coat film. Drying before curing to cause phase separation in advance is preferable because it effectively removes the solvent in the coating film having fine unevenness, and it also allows unevenness of the desired size to be formed in the hard coat film, which is a cured film.

As another method for phase separation before curing, a method of irradiating the coating film with active energy rays to cause phase separation can also be used. As the active energy rays to be irradiated, for example, light with an exposure dose of 0.1 to 3.5 J/cm ² , preferably light with an exposure dose of 0.5 to 1.5 J/cm ² can be used. The wavelength of the irradiated light is not particularly limited, but for example, irradiation light having a wavelength of 360 nm or less can be used. For example, when 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one or the like is used as the polymerization initiator, it is preferable to irradiate light having a wavelength of about 310 nm or about 360 nm, and more preferably light having a wavelength of about 360 nm. Such light can be obtained using a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, or the like. By irradiating light in this way, phase separation and curing will occur. By irradiating light to cause phase separation, it is preferable because unevenness in the surface shape caused by uneven drying of the solvent contained in the curable composition can be avoided.

The hard coat film of the present invention having a fine uneven structure on the surface is formed by curing the coating film obtained by coating the curable composition or the coating film dried after coating. The curing can be performed by irradiating the coating film with light using a light source that emits active energy rays of a wavelength according to need. It is preferable that the light irradiation for curing is performed so that the accumulated light amount is 100 mJ/ ^cm2 or more and 20,000 mJ/ ^cm2 or less. As the light source, a high pressure mercury lamp, an ultra-high pressure mercury lamp, etc. can be used.

[Physical Properties]
The hard coat film of the present invention provides a favorable unevenness on the surface by phase separation between the component constituting the recesses and the component convexities of the surface unevenness structure of the hard coat film.

The surface roughness (Ra) of the hard coat film of the present invention measured by a white light interference microscope is preferably 0.05 to 1.5 μm, more preferably 0.1 to 1.2 μm, even more preferably 0.15 to 1.0 μm, particularly preferably 0.2 to 0.85 μm, and most preferably 0.25 to 0.65 μm. By having a surface roughness (Ra) equal to or greater than the above lower limit, good anti-blocking properties can be obtained. On the other hand, by having a surface roughness (Ra) equal to or less than the above upper limit, both low haze and anti-Newton ring properties can be achieved.

For the hard coat film of the present invention, the surface roughness (Rz) measured by a white light interference microscope is preferably 0.05 to 1.5 μm, more preferably 0.1 to 7 μm, even more preferably 0.5 to 5.5 μm, particularly preferably 1 to 5 μm, and most preferably 2 to 4.5 μm. By having a surface roughness (Rz) equal to or greater than the above lower limit, good anti-blocking properties can be obtained. On the other hand, by having a surface roughness (Rz) equal to or less than the above upper limit, both low haze and anti-Newton ring properties can be achieved.

The hard coat film of the present invention also has good hardness. For example, the pencil hardness of a hard coat film formed with the curable composition of the present invention and having a film thickness of 3 μm, as measured according to JIS K-5600, is preferably H or more, and more preferably 2H or more.

The hard coat film of the present invention also has good transparency. For example, the total light transmittance of a hard coat film formed with a thickness of 2 to 3 μm using the curable composition of the present invention is 85% or more, preferably 90% or more, and the haze is 2.0% or less, preferably 1.8% or less, more preferably 1.5% or less, even more preferably less than 1.0%, and particularly preferably less than 0.5%.

The surface roughness (Ra), surface roughness (Rz), total light transmittance, and haze of the hard coat film are measured by the methods described in the Examples section below.

[Application]
The film laminate obtained by laminating the above-mentioned substrate and the hard coat film of the present invention can be used together with a light source to be applied to a display device. In this case, the substrate is preferably a light-transmitting substrate. The light source is preferably disposed on the back surface of the substrate, i.e., on the surface of the substrate opposite to the surface on which the hard coat film is laminated, and irradiates light toward the substrate from there.

The light source is not particularly limited as long as it can emit light. Examples include light-emitting diodes, cold cathode fluorescent lamps, hot cathode fluorescent lamps, and EL elements, but liquid crystal modules, backlight units, and the like may also be used.

The liquid crystal module includes the light source, and further has a configuration in which a polarizing plate/liquid crystal cell/polarizing plate are arranged on the light source in this order. The liquid crystal cell is not particularly limited as long as it is one that is generally used in liquid crystal display devices. For example, TN (Twisted Nematic) type liquid crystal cell, STN (Super Twisted Nematic) type liquid crystal cell, HAN (Hybrid Alignment Nematic) type liquid crystal cell, IPS (In Plane Switching) type liquid crystal cell, VA (Vertical Alignment) type liquid crystal cell, MVA (Multiple Vertical Alignment) type liquid crystal cell, OCB (Optical Compensated Bend) type liquid crystal cell, etc. can be mentioned. Such a display device may further include a retardation plate, a brightness enhancement film, a light guide plate, a light diffusion plate, a light diffusion sheet, a light collecting sheet, a reflector, etc.

Display devices using film laminates having the hard coat film of the present invention can be applied to flat panel displays such as liquid crystal displays (liquid crystal displays), LEDs (light emitting diode displays), ELDs (electroluminescent displays), VFDs (fluorescent displays), and PDPs (plasma display panels).

Display devices using film laminates having the hard coat film of the present invention can be used in applications such as touch panels, which have a mechanism for operating equipment by pressing the display on the screen, and are useful in, for example, bank ATMs, vending machines, personal digital assistants (PDAs), copiers, facsimiles, game machines, information display devices installed in facilities such as museums and department stores, car navigation systems, multimedia stations (multifunction terminals installed in convenience stores), mobile phones, and monitor devices for railway cars.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. Note that the various manufacturing conditions and evaluation result values in the following examples are meant as preferred upper or lower limit values in the embodiments of the present invention, and the preferred range may be a range defined by a combination of the above-mentioned upper or lower limit values and the values of the following examples or values between the examples.

The weight average molecular weights of the polymers (A-1), (A-2), (a-1), and (a-2) synthesized in the following synthesis examples were measured under the following measurement conditions.

<Conditions for measuring weight average molecular weight (Mw)>
Equipment: Tosoh Corporation "HLC-8120GPC"
Column: Tosoh Corporation
"TSKgel Super H1000+H2000+H3000"
Detector: Differential refractive index detector (RI detector/built-in)
Solvent: Tetrahydrofuran Temperature: 40°C
Flow rate: 0.5mL/min Injection volume: 10μL
Concentration: 0.2% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polystyrene equivalent

The viscosities of the polymer solutions (A-1), (A-2), (a-1), and (a-2) synthesized in the following Synthesis Examples 1 to 4 and the resin solutions (B-1) to (B-6) prepared in the following Preparation Examples 1 to 6 were measured using an E-type viscometer under the following measurement conditions.

<Viscosity measurement conditions>
Solid content: 30% by weight
Temperature: 25°C
Equipment: TOKIMEC E-type viscometer TV-20

The amount of unsaturated double bonds in the polymers (A-1), (A-2), (a-1), and (a-2) was calculated from the amount of monomer used in the reaction. The consumption rate of acrylic acid was calculated by quantifying the amount of unreacted acrylic acid using the acid-base titration described below, and the reaction rate was calculated.

<Titration of acrylic acid with potassium hydroxide solution>
0.5 g of the reaction solution was dispensed into an Erlenmeyer flask and diluted to 10 g with propylene glycol monomethyl ether solution.
To this solution, about 0.1 g of an ethanol solution (10%) of phenolphthalein was added as an indicator, and a 0.1 N ethanolic potassium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise until the solution turned red. The amount of unreacted acrylic acid was determined from the amount added.

The SP value of each resin was measured using the method described above.

[Synthesis Example 1: Synthesis of polymer (A-1) containing amide group and unsaturated double bond]
To a 2000 mL separable flask equipped with a thermometer, a stirrer and a reflux condenser, 359.6 g of propylene glycol monomethyl ether was added.
Meanwhile, a monomer solution was prepared by adding 180.0 g of glycidyl methacrylate, 180.0 g of acryloylmorpholine, 180.0 g of propylene glycol monomethyl ether, and 1.80 g of 2,2'-azobis(2,4-dimethylvaleronitrile) to a 1000 mL measuring cylinder.
Thereafter, the stirrer of the separable flask was started, and then nitrogen gas was introduced into the separable flask and the measuring cylinder at a flow rate of 300 mL/min for about 1 hour.

Next, the separable flask was immersed in an oil bath and heated to an internal temperature of 65°C. The monomer solution prepared in the measuring cylinder was then pumped into the separable flask and added dropwise over a period of 2 hours to carry out radical polymerization. After the dropwise addition was complete, stirring was continued for another 2 hours at an internal temperature of 65°C, after which 0.9 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added and reacted for 3 hours, after which 258.8 g of propylene glycol monomethyl ether and 1.55 g of p-methoxyphenol were added and heated to 100°C.

Next, 93.07 g of acrylic acid and 6.80 g of triphenylphosphine were added and reacted at 110° C. for 6 hours to obtain a (meth)acryloyl copolymer (A-1) having an amide group and an unsaturated double bond and an unsaturated double bond amount (acryloyl equivalent (amount of acryloyl group introduced)) of 2.82 mmol/g.
The resulting (meth)acryloyl copolymer (A-1) had an SP value of 19.1 and a consumption rate of acrylic acid of 93%.
The viscosity of this solution (solid content: 30% by weight) was 1,050 mPa·s at 25° C. The weight average molecular weight (Mw) of the (meth)acryloyl copolymer (A-1) was 22,500.

[Synthesis Example 2: Synthesis of polymer (A-2) containing amide group and unsaturated double bond]
To a 2000 mL separable flask equipped with a thermometer, a stirrer and a reflux condenser, 359.6 g of propylene glycol monomethyl ether was added.
Meanwhile, a monomer solution was prepared by adding 180.0 g of glycidyl methacrylate, 180.0 g of acryloylmorpholine, 180.0 g of propylene glycol monomethyl ether, 1.80 g of 2,2'-azobis(2,4-dimethylvaleronitrile), and 7.2 g of γ-trimethoxysilylpropanethiol (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) to a 1000 mL measuring cylinder.
Thereafter, the stirrer of the separable flask was started, and then nitrogen gas was introduced into the separable flask and the measuring cylinder at a flow rate of 300 mL/min for about 1 hour.

Next, the separable flask was immersed in an oil bath and heated to an internal temperature of 65°C. The monomer solution prepared in the measuring cylinder was then pumped into the separable flask and added dropwise over a period of 2 hours to carry out radical polymerization. After the dropwise addition was complete, stirring was continued for another 2 hours at an internal temperature of 65°C, after which 0.9 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added and reacted for 3 hours, after which 258.8 g of propylene glycol monomethyl ether and 1.55 g of p-methoxyphenol were added and heated to 100°C.

Next, 93.07 g of acrylic acid and 6.80 g of triphenylphosphine were added and reacted at 110°C for 6 hours to obtain a (meth)acryloyl copolymer (A-2) having an amide group and an unsaturated double bond and an unsaturated double bond content of 2.81 mmol/g.

The resulting (meth)acryloyl copolymer (A-2) had an SP value of 19.1 and an acrylic acid consumption rate of 93%.
The viscosity of this solution (solid content 30% by weight) was 220 mPa·s at 25° C. The weight average molecular weight (Mw) of the (meth)acryloyl copolymer (A-2) was 10,080.

[Synthesis Example 3: Synthesis of polymer (a-1) (for comparison) containing no amide group but containing unsaturated double bonds]
To a flask equipped with a thermometer, a stirrer, and a reflux condenser, 157.3 g of propylene glycol monomethyl ether, 98.0 g of glycidyl methacrylate, 1.0 g of methyl methacrylate, 1.0 g of ethyl acrylate, 1.9 g of mercaptopropyltrimethoxysilane, 1.0 g of 2,2'-azobis(2,4-dimethylvaleronitrile), and 1.9 g of γ-trimethoxysilylpropanethiol (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and the mixture was allowed to react at 65°C for 3 hours.
Then, 0.5 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was further added and reacted for 3 hours, after which 138.1 g of propylene glycol monomethyl ether and 0.45 g of p-methoxyphenol were added and heated to 100°C.
Next, 50.7 g of acrylic acid and 3.08 g of triphenylphosphine were added and reacted at 110° C. for 6 hours to obtain a (meth)acryloyl copolymer (a-1) having an unsaturated double bond amount of 4.62 mmol/g.

The resulting (meth)acryloyl copolymer (a-1) had an SP value of 17.4 and a consumption rate of acrylic acid of 94%.
The viscosity of this solution (solid content: 30% by weight) was 100 mPa·s at 25° C. The weight average molecular weight (Mw) of the (meth)acryloyl copolymer (a-1) was 17,700.

[Synthesis Example 4: Synthesis of polymer (a-2) (for comparison) containing no amide group but containing unsaturated double bonds]
To a flask equipped with a thermometer, a stirrer, and a reflux condenser, 155.1 g of propylene glycol monomethyl ether, 76.0 g of glycidyl methacrylate, 24.0 g of methyl methacrylate, 1.0 g of ethyl acrylate, 1.9 g of mercaptopropyltrimethoxysilane, 1.0 g of 2,2'-azobis(2,4-dimethylvaleronitrile), and 1.9 g of γ-trimethoxysilylpropanethiol (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and the mixture was allowed to react at 65°C for 3 hours.
Then, 0.5 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was further added and reacted for 3 hours, after which 185.6 g of propylene glycol monomethyl ether and 0.49 g of p-methoxyphenol were added and heated to 100°C.
Next, 39.3 g of acrylic acid and 2.82 g of triphenylphosphine were added and reacted at 110° C. for 6 hours to obtain a (meth)acryloyl copolymer (a-2) having an unsaturated double bond amount of 4.59 mmol/g.

The resulting (meth)acryloyl copolymer (a-2) had an SP value of 17.1 and an acrylic acid consumption rate of 95%.
The viscosity of this solution (solid content: 30% by weight) was 200 mPa·s at 25° C. The weight average molecular weight (Mw) of the (meth)acryloyl copolymer (a-2) was 20,700.

The composition (parts by weight) of the raw material components used in Synthesis Examples 1 to 4 is summarized in Table 1. In the table, "-" indicates that the component was not used.

[Preparation Example 1: Preparation of resin solution (B-1)]
700 g of methyl ethyl ketone was placed in a 2000 mL eggplant flask and heated to an internal temperature of 80°C. Next, 300 g of a (meth)acrylic polymer (methyl methacrylate-methyl acrylate copolymer Parapet HR-L manufactured by Kuraray, weight average molecular weight (Mw) 80,700 (measured value measured under the following measurement conditions)) was added little by little, and stirring was continued until completely dissolved. The viscosity of this resin solution (solid content 30% by weight) was 1,100 mPa·s. The SP value of the (meth)acrylic polymer Parapet HR-L used was 13.5.

<Conditions for measuring weight average molecular weight>
Equipment: Tosoh Corporation "HLC-8120GPC"
Column: Tosoh Corporation "TSKgel Super H3000+H4000+H6000"
Detector: Differential refractive index detector (RI detector/built-in)
Solvent: Tetrahydrofuran Temperature: 40°C
Flow rate: 0.5ml/min Injection volume: 10μL
Concentration: 0.2% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polystyrene equivalent

[Preparation Example 2: Preparation of resin solution (B-2)]
The same procedure was carried out except that the resin used in the preparation of the resin solution was BR-75 (acrylic copolymer, weight average molecular weight (Mw) 85,000 (catalog value)) manufactured by Mitsubishi Rayon. The viscosity of this resin solution (solid content 30% by weight) was 470 mPa s. The SP value of the (meth)acrylic polymer BR-75 used was 13.5.

[Preparation Example 3: Preparation of resin solution (B-3)]
The same procedure was carried out except that the resin used in preparing the resin solution was BR-80 (acrylic copolymer, weight average molecular weight (Mw) 95,000 (catalog value)) manufactured by Mitsubishi Rayon Co., Ltd. The viscosity of this resin solution (solid content 30% by weight) was 1,900 mPa s. The SP value of the (meth)acrylic polymer BR-80 used was 13.4.

[Preparation Example 4: Preparation of resin solution (B-4)]
The same procedure was carried out except that the resin used in preparing the resin solution was BR-84 (acrylic copolymer, weight average molecular weight (Mw) 120,000 (catalog value)) manufactured by Mitsubishi Rayon. The viscosity of this resin solution (solid content 30% by weight) was 1,940 mPa s. The SP value of the (meth)acrylic polymer BR-84 used was 13.6.

[Preparation Example 5: Preparation of resin solution (B-5)]
The same procedure was carried out except that the resin used in preparing the resin solution was BR-85 (acrylic copolymer, weight average molecular weight (Mw) 280,000 (catalog value)) manufactured by Mitsubishi Rayon. The viscosity of this resin solution (solid content 30% by weight) was greater than 50,000 mPa s. The SP value of the (meth)acrylic polymer BR-85 used was 13.5.

The physical properties of the (meth)acryloyl copolymers (A-1), (A-2), (a-1), and (a-2) and the (meth)acrylic polymers of the resin solutions (B-1) to (B-5) are summarized in Table 2. The viscosities of the (meth)acryloyl copolymers (A-1), (A-2), (a-1), and (a-2) are measured at 25°C in 30% by weight propylene glycol monomethyl ether (PGME), and the viscosities of the (meth)acrylic polymers used in the resin solutions (B-1) to (B-5) are measured at 25°C in 30% by weight methyl ethyl ketone (MEK).

[Example 1]
<Preparation of Curable Composition>
A glass sample bottle was mixed with 7.32 parts by weight of the (meth)acryloyl copolymer (A-1), 2.05 parts by weight of the resin solution (B-1), and 4.51 parts by weight of dipentaerythritol hexaacrylate (DPHA (SP value: 12.1)) as the polyfunctional (meth)acrylate (C-1), and then 0.183 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (BASF Corporation's "Irgacure (registered trademark) 184") was added as a polymerization initiator, and 15.94 parts by weight of methyl ethyl ketone was further added to obtain a curable composition.

<Coating process>
The obtained curable composition was applied to a transparent biaxially stretched PET film having a thickness of 188 μm (haze value: 0.8%; product name: Diafoil (registered trademark) O321E, manufactured by Mitsubishi Plastics, Inc.) using a bar coater so that the coating thickness after drying would be 2 to 3 μm, and the film was dried by heating at 80° C. for 1 minute.

<Curing process>
The PET film on which the coating of the curable composition was formed was irradiated with ultraviolet light from a high pressure mercury lamp with an output density of 120 W/cm at a position 15 cm below the light source using an "EYE UV METER UVPF-A1, PD365" manufactured by EYE GRAPHICS, Inc., so that the cumulative light amount was 500 mJ/ ^cm2 , to obtain a cured film. The film laminate on which this cured film (hard coat film) was formed was subjected to the following evaluations. The results are shown in Table 3.

In Table 3, the amounts of the curable composition are shown as converted amounts when the total of the (meth)acryloyl copolymer (A-1) and the (meth)acrylic polymer and DPHA (C-1) in the resin solution (B-1) is taken as 100 parts by weight, and all amounts are pure amounts. The same applies to the following Examples 2 to 9 and Comparative Examples 1 to 13.

[Evaluation of hard coat film]
<Ra and Rz (arithmetic mean roughness)>
The measurements were performed using a white light interference microscope ("WYKO NP9100" manufactured by Nippon Veeco Co., Ltd.) to determine the arithmetic mean roughness (Ra) and (Rz) in an area of 900 μm×1300 μm in accordance with JIS B0601-1994.
Ra and Rz (JIS B 0601-1994) refer to values expressed in micrometers (μm) that can be calculated by a formula in which a reference length is cut out from a roughness curve in the direction of the average line, the X axis is plotted in the direction of the average line of the cut out portion, and the Y axis is plotted in the direction of the longitudinal magnification when the roughness curve is expressed as y = f(x).

<Total light transmittance/haze>
The total light transmittance (Tt (%)) of the hard coat film was calculated by measuring the incident light intensity (T0) on the hard coat film and the total transmitted light intensity (T1) that transmitted through the hard coat film, according to the following formula.
Tt (%) = (T1/T0) x 100
The total light transmittance can be measured, for example, by using a haze meter (SH7000, manufactured by Nippon Denshoku Industries Co., Ltd.).
The haze of the hard coat film was calculated according to the following formula in accordance with JIS K-7136 (2000).
H (%) = (Td/Tt) x 100
H: Haze (%)
Td: Diffuse transmittance (%)
Tt: Total light transmittance (%)

<Glare>
The obtained film laminate was placed on a liquid crystal display of about 123 dpi (diagonal 10.4 inches, XGA (1,024 x 768 dots)), and the presence or absence of glare was visually confirmed. Those with absolutely no noticeable glare were rated as excellent (◎), those with no noticeable glare but inferior to those of ◎ were rated as good (◯), those with only a faint glare were rated as somewhat good (△), and those with clearly noticeable glare were rated as poor (×).

<Anti-Newton Ring (ANR) Property>
A 5 mm thick glass plate was placed on the hard coat film of the film laminate so that the glass plate and the hard coat film were in contact with each other, and then the hard coat film was pressed against the glass plate. The presence or absence of Newton's rings in the area where the hard coat film and the glass plate were in contact was visually observed from an oblique direction of 60 degrees.
Those in which no Newton's rings were observable were rated as excellent (◎), those in which no Newton's rings were observable but were inferior to those in which Newton's rings were observable were rated as good (◯), those in which the rings were faintly observable were fairly good (△), and those in which the rings were clearly observable were rated as poor (×).

<Microscopic Raman Spectroscopic Measurement>
A confocal Raman microscope spectrometer (RAMANTouch manufactured by Nanophoton Corporation) was used to perform Raman spectroscopy of the hard coat film. Excitation light was 532 nm (laser output: 0.1 mW or less), introduced into the microscope, and focused on the sample by the objective lens. Backscattering from the sample was collected by the same objective lens and passed through a pinhole to obtain a confocal effect. The Rayleigh scattered light was removed by a notch filter, introduced into a spectroscope (diffraction grating: 300 groove/mm), and a Raman spectrum was obtained by a CCD camera.

In the above Raman spectroscopy, the piezo stage was moved with an exposure time of 10 s at each point, a Raman spectrum was obtained at each point, and Raman mapping was performed. For the Raman spectrum at each point, the Raman band with a peak at 3100 to 3400 cm ⁻¹ attributed to DPHA was used as an indicator of the multifunctional (meth)acrylate (C-1), and this was used as the reference peak. Furthermore, the Raman band with a peak at 950 to 1050 cm ⁻¹ was used as an indicator of the (meth)acryloyl copolymer (A-1), and the Raman band with a peak at 800 to 850 cm ⁻¹ was used as an indicator of the polymer (B)-1. The results of Raman mapping based on the respective peak intensities are shown in FIG. 1.

Figure 1 shows that the recesses in the hard coat film are primarily composed of domains of (meth)acryloyl copolymer (A-1), while the protrusions are composed of domains of resin (B-1) and polyfunctional (meth)acrylate (C-1).

[Examples 2 to 9, Comparative Examples 1 to 13]
A hard coat film was obtained in the same manner as in Example 1, except that the formulation of the curable composition was changed as shown in Tables 3 and 4. Ra, Rz, total light transmittance, haze, glare, and ANR were evaluated in the same manner as in Example 1, and the results are shown in Tables 3 and 4.
In Tables 3 and 4, “polymer (A)”, “polymer (B)”, and “polyfunctional (meth)acrylate (C)” are respectively described as “component (A)”, “component (B)”, and “component (C)”.

Tables 3 and 4 show that the hard coat film of the present invention, which uses components (A), (B), and (C), has excellent anti-Newton ring properties and transparency, and is free of glare problems.

Claims (5)

A hard coat film having an uneven surface structure.
the recess is constituted by a domain derived from a polymer (A) containing an amide group and an unsaturated double bond and having a solubility parameter (SP value) of 18 to 19.4 ;
the convex portions are formed of domains derived from a polymer (B) having a solubility parameter (SP value) of 12 to 14 and a polyfunctional (meth)acrylate (C) having an SP value of 12 to 14 ,
The surface roughness (Ra) measured by a white light interference microscope is 0.25 to 1.2 μm;
a cured product of a curable composition comprising a polymer (A), a polymer (B), and a polyfunctional (meth)acrylate (C), in which the ratio of [weight of polymer (A)]:[total weight of polymer (B) and polyfunctional (meth)acrylate (C)] is 20:80 to 35:65 and the ratio of [weight of polymer (B)]:[weight of polyfunctional (meth)acrylate (C)] is 10:90 to 35:65,
The amount of unsaturated double bonds in the polymer (A) is 2 to 4 mmol/g,
The polymer (B) is a (meth)acrylic polymer,
A hard coat film, comprising a polymer (A) having a side chain of a structural unit represented by the following formula (1):

(In formula (1), R represents the main chain portion of the polymer (A), and R1 ^represents a hydrogen atom or a methyl group.) 2. The hard coat film according to claim 1 , wherein the viscosity of the polymer (A) measured at 25° C. and at a concentration of 30% by weight in propylene glycol monomethyl ether is 100 to 4,000 mPa·s. 3. The hard coat film according to claim 1, which has a thickness of 1 to 10 μm. A curable composition comprising a polymer (A) containing an amide group and an unsaturated double bond and having a solubility parameter (SP value) of 18 to 19.4 , a polymer (B) having a solubility parameter (SP value) of 12 to 14 , and a polyfunctional (meth)acrylate (C) having an SP value of 12 to 14 , wherein the ratio of [weight of polymer (A)]:[total weight of polymer (B) and weight of polyfunctional (meth)acrylate (C)] is 20:80 to 35:65 ,
[the weight of the polymer (B)]:[the weight of the polyfunctional (meth)acrylate (C)] is 10:90 to 35:65,
The amount of unsaturated double bonds in the polymer (A) is 2 to 4 mmol/g,
The polymer (B) is a (meth)acrylic polymer,
A curable composition, wherein the polymer (A) has a side chain of a structural unit represented by the following formula (1):

(In formula (1), R represents the main chain portion of the polymer (A), and R1 ^represents a hydrogen atom or a methyl group.) The curable composition according to claim 4 , wherein the viscosity of the polymer (A) measured at 25° C. and at a concentration of 30% by weight in propylene glycol monomethyl ether is 100 to 4,000 mPa·s.

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