CN119630995A

CN119630995A - Optical laminate and image display device

Info

Publication number: CN119630995A
Application number: CN202380055804.9A
Authority: CN
Inventors: 久野和树; 山本悟士; 木村智之; 形见普史
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2022-07-22
Filing date: 2023-07-21
Publication date: 2025-03-14
Also published as: JP2024014849A; WO2024019160A1; TW202411375A

Abstract

The present invention provides an optical laminate suitable for use in image display devices that may be exposed to high temperature environments. An optical laminate is provided with an adhesive sheet formed from a photocurable composition containing a monomer group and/or a partial polymer of the monomer group, and a retardation film. The pressure-sensitive adhesive sheet is in contact with the retardation film directly or via a layer having a thickness of 10 μm or less. The amount of residual monomer contained in the adhesive sheet was 16000ppm (weight basis) or less.

Description

Optical laminate and image display device

Technical Field

The present invention relates to an optical laminate and an image display device.

Background

Various image display devices, such as liquid crystal display devices and Electroluminescent (EL) display devices, generally include an optical laminate including an optical film such as a polarizing film and an adhesive sheet. An adhesive sheet is generally used for bonding optical films included in the optical laminate and bonding the optical laminate to the image display panel. As the pressure-sensitive adhesive sheet, a sheet obtained by curing a monomer group including an acrylic monomer, a silicone monomer, and the like by polymerization and crosslinking is typical. Patent document 1 discloses an adhesive sheet formed of a photocurable composition (hereinafter, "photocurable adhesive sheet"). As a different type from this, there is an adhesive sheet (hereinafter, "thermosetting adhesive sheet") formed by curing a layer containing an adhesive composition and a solvent by heat.

Prior art literature

Patent literature

Japanese patent application laid-open No. 2016-155981

Disclosure of Invention

Problems to be solved by the invention

When the photocurable pressure-sensitive adhesive sheet is used for an optical laminate, there is a tendency that the image quality of the image display device is impaired, compared with the case where the thermosetting pressure-sensitive adhesive sheet is used. The above problems are particularly likely to occur in an image display device for a vehicle or the like which may be exposed to a high temperature environment.

The object of the present invention is to provide an optical laminate suitable for use in an image display device that may be exposed to a high temperature environment.

Means for solving the problems

The optical laminate generally contains residual monomers such as unreacted monomers remaining in the adhesive sheet. According to the studies of the present inventors, among optical films that may be included in the optical laminate, the retardation film is susceptible to the influence of residual monomers. Typically, the retardation film is prone to cracking caused by repeated changes in ambient temperature. In addition, according to studies, the amount of residual monomers contained in the photocurable adhesive sheet tends to be larger than that of the thermosetting adhesive sheet. This may be affected by the fact that atmospheric oxygen tends to inhibit curing of the photocurable composition particularly in the vicinity of the surface of the sheet.

In view of the above, the present invention provides an optical laminate comprising:

adhesive sheet formed from photocurable composition containing monomer group and/or partial polymer of the monomer group, and method for producing the same

A phase difference film, which is formed of a film,

The pressure-sensitive adhesive sheet is in contact with the retardation film directly or via a layer having a thickness of 10 μm or less,

The amount of residual monomer contained in the pressure-sensitive adhesive sheet was 16000ppm (weight basis) or less.

In another aspect, the present invention provides an image display device comprising the optical laminate of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an optical laminate suitable for use in an image display device that may be exposed to a high-temperature environment can be provided.

Drawings

Fig. 1 is a cross-sectional view schematically showing an example of an optical laminate of the present invention.

Fig. 2 is a cross-sectional view schematically showing an example of the optical laminate of the present invention.

Fig. 3 is a cross-sectional view schematically showing an example of the optical laminate of the present invention.

Fig. 4A is a schematic diagram for explaining an example of a method for forming the pressure-sensitive adhesive sheet provided in the optical laminate of the present invention.

Fig. 4B is a schematic diagram for explaining an example of a method for forming the pressure-sensitive adhesive sheet provided in the optical laminate of the present invention.

Fig. 4C is a schematic diagram for explaining an example of a method for forming the pressure-sensitive adhesive sheet provided in the optical laminate of the present invention.

Detailed Description

An optical laminate according to claim 1 of the present invention comprises:

A phase difference film, which is formed of a film,

In aspect 2 of the present invention, for example, the optical laminate of aspect 1 includes two pressure-sensitive adhesive sheets disposed so as to sandwich the retardation film.

In the 3 rd aspect of the present invention, for example, the optical laminate of the 1 st or 2 nd aspect is provided with two or more of the adhesive sheets, and the amount of the residual monomer contained in the two or more adhesive sheets is 16000ppm (weight basis) or less in total.

In the 4 th aspect of the present invention, for example, the optical laminate according to any one of the 1 st to 3 rd aspects further comprises a polarizing film.

In the 5 th aspect of the present invention, for example, in the optical laminate of the 4 th aspect, the polarizing film and the retardation film sandwich the pressure-sensitive adhesive sheet.

In the invention according to claim 6, for example, in the optical laminate according to any one of claims 1 to 5, the monomer group includes a (meth) acrylic monomer.

In the 7 th aspect of the present invention, for example, in the optical laminate according to any one of the 1 st to 6 th aspects, the monomer group includes a carboxyl group-containing monomer.

In the 8 th aspect of the present invention, for example, in the optical laminate of the 7 th aspect, the content of the carboxyl group-containing monomer in the monomer group is 4.5 wt% or more.

In the 9 th aspect of the present invention, for example, in the optical laminate according to any one of the 1 st to 8 th aspects, the monomer group includes a nitrogen atom-containing monomer.

In the 10 th aspect of the present invention, for example, in the optical laminate according to any one of the 1 st to 9 th aspects,

The photocurable composition contains a photopolymerization initiator,

The photopolymerization initiator is a compound having a chemical structure represented by the following formula (1) in a molecule,

[ Chemical formula 1]

R ¹ and R ² of the above formula (1) are each independently a C1-C8 alkyl group, a C1-C4 alkyl group in which a hydrogen atom is substituted with-OH, a C1-C4 alkoxy group, -CN, -COOR ⁵¹、-OOCR⁵² or-NR ⁵³R⁵⁴, a C3-C6 alkenyl group, or-CH ₂-C₆H₄-R⁵⁵,

R ¹ and R ² are optionally bonded to each other to form a C2-C9 alkylene group, or a C3-C6 oxyalkylene group, or an azaalkylene group,

X is-OR ⁵⁶, OR-NR ⁵⁷R⁵⁸,

R ⁵¹ is C1-C8 alkyl,

R ⁵² is C1-C4 alkyl,

R ⁵³ and R ⁵⁴ are each independently a hydrogen atom, a C1-C12 alkyl group, a C2-C4 alkyl group in which the hydrogen atom is substituted with at least one group selected from the group consisting of-OH, a C1-C4 alkoxy group, -CN and-COOR ⁵⁹, a C3-C5 alkenyl group, or a cyclohexyl group,

R ⁵³ and R ⁵⁴ may be C3-C9 alkylene groups bonded to each other and optionally interrupted by-O-or-N (R ⁶⁰) -,

R ⁵⁵ is C1-C4 alkyl,

R ⁵⁶ is a hydrogen atom, -SiR ⁶² ₃, C1-C8 alkyl, or C3-C6 alkenyl,

R ⁵⁷ and R ⁵⁸ are C1-C12 alkyl, C2-C4 alkyl in which a hydrogen atom is substituted with at least one group selected from the group consisting of-OH, C1-C4 alkoxy, -CN and-COOR ⁶³, C3-C5 alkenyl, or cyclohexyl,

R ⁵⁷ and R ⁵⁸ may be C3-C9 alkylene groups bonded to each other and optionally interrupted by-O-or-N (R ⁶⁴) -,

R ⁵⁹ is C1-C4 alkyl,

R ⁶⁰ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a C1-C4 hydroxyalkyl group, -CH ₂CH₂-COOR⁶¹ or-CH ₂CH₂ CN,

R ⁶¹ is C1-C4 alkyl,

R ⁶² is C1-C6 alkyl,

R ⁶³ is C1-C4 alkyl,

R ⁶⁴ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a C1-C4 hydroxyalkyl group, -CH ₂CH₂-COOR⁶⁵ or-CH ₂CH₂ CN,

R ⁶⁵ is C1-C4 alkyl,

The chemical structure may be bonded to a hydrogen atom or a substituted structure of a hydrogen atom via a carbon atom represented by the formula (1).

In the 11 th aspect of the present invention, for example, in the optical laminate according to any one of the 1 st to 10 th aspects, the photocurable composition contains a 1 st photopolymerization initiator having a relatively small 1 st reaction rate and a 2 nd photopolymerization initiator having a relatively large 2 nd reaction rate, and the ratio of the 2 nd reaction rate to the 1 st reaction rate is represented by a ratio of a polymerization rate a evaluated by the following measurement method using only each of the photopolymerization initiators, and is 1.1 or more,

[ Measurement method ]

A mixed solution of 99 parts by weight of n-butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate as monomers and 0.1 part by weight of a photopolymerization initiator to be evaluated was irradiated with ultraviolet light to prepare a monomer slurry in which the above monomers were partially polymerized. The irradiation of the ultraviolet ray is performed until the viscosity of the mixed solution at 30 ℃ reaches 20 Pa.s. Then, a coating layer having a thickness of 20 μm formed from the monomer slurry thus produced was formed between a pair of polyethylene terephthalate (PET) flakes each having a thickness of 75 μm, and then, the coating layer was irradiated with ultraviolet rays having an LED having a peak wavelength of 340 nm.+ -. 10nm as a light source from one of the PET flakes. The illuminance and irradiation time of the irradiated ultraviolet ray were set to 4mW/cm ² and 1200 seconds, respectively. The polymerization rate of the monomer measured for the coating layer after the photo-curing by irradiation of the ultraviolet rays is determined as the polymerization rate a.

In the 12 th aspect of the present invention, for example, in the optical laminate according to any one of the 1 st to 11 th aspects, the pressure-sensitive adhesive sheet has a surface to which a surface modification treatment is applied.

In aspect 13 of the present invention, for example, in the optical laminate according to any one of aspects 1 to 12, the thickness of the pressure-sensitive adhesive sheet is 50 μm or less.

In the 14 th aspect of the present invention, for example, in the optical laminate according to any one of the 1 st to 13 th aspects, the anchoring force of the adhesive sheet to the retardation film is 13N/25mm or more.

An image display device according to claim 15 of the present invention includes the optical laminate according to any one of claims 1 to 14.

The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented within a range not departing from the gist of the present invention.

[ Optical laminate ]

An example of the optical laminate of the present embodiment is shown in fig. 1. The optical laminate 10 (10A) of fig. 1 includes an adhesive sheet 1 and a retardation film 2. The pressure-sensitive adhesive sheet 1 is directly in contact with the retardation film 2. However, the pressure-sensitive adhesive sheet 1 and the retardation film 2 may be in contact with each other with a layer having a thickness of 10 μm or less, preferably 5 μm or less interposed therebetween. The layer may be a single layer or a plurality of layers. Examples of such layers are primer layers, antistatic layers, protective layers, coating layers and hard coats. The optical laminate 10 may be used in the form of an optical film with an adhesive sheet.

(Adhesive sheet)

The adhesive sheet 1 is formed from a photocurable composition containing a monomer group and/or a partial polymer of the monomer group. The photocurable composition is a composition which forms the adhesive sheet 1 by irradiation with light. The amount of residual monomer contained in the adhesive sheet 1 was 16000ppm or less. The amount of the residual monomer may be 15000ppm or less, 12000ppm or less, 10000ppm or less, 9000ppm or less, 8000ppm or less, 7000ppm or less, 6000ppm or less, 5000ppm or less, 4500ppm or less, 4000ppm or less, 3500ppm or less, 3000ppm or less, 2500ppm or less, 2000ppm or less, and further 1500ppm or less. The pressure-sensitive adhesive sheet 1 having a small amount of residual monomer is less likely to cause cracking of the retardation film 2 due to changes in ambient temperature. In addition, when the amount of the residual monomer is 16000ppm or less, the adhesive sheet 1 having a small amount of 3500ppm or less, 2500ppm or less, or 2000ppm or less is suitable for improving the anchoring force to the retardation film 2, and the anchoring force to the retardation film 2 is also suitable for improving the anchoring force to the retardation film 2. In the adhesive sheet 1 with improved anchoring force, there is a possibility that the cohesive force of the adhesive sheet 1 is improved due to a decrease in the amount of the low-molecular compound contained in the adhesive sheet 1. The lower limit of the amount of the residual monomer is not particularly limited, and may be, for example, 300ppm or more, 500ppm or more, and further 750ppm or more. The adhesive sheet 1 having the lower limit of the amount of the residual monomer in the above range is suitable for suppressing deterioration of the phase difference film 2 which may occur due to exposure to irradiation of light or heat in the case where the adhesive sheet 1 is formed by irradiating light to a laminate including the phase difference film 2. In this specification, "ppm" is all weight basis.

The amount of residual monomer in the adhesive sheet 1 can be evaluated by Gas Chromatography (GC) analysis.

Fig. 2 shows another example of the optical laminate of the present embodiment. The optical laminate 10 (10B) of fig. 2 includes two pressure-sensitive adhesive sheets 1 (1A, 1B) disposed so as to sandwich the retardation film 2. The optical laminate 10B includes, in order, an adhesive sheet 1A, a phase difference film 2, and an adhesive sheet 1B. The amount of residual monomer contained in the two pressure-sensitive adhesive sheets 1A and 1B, that is, the amount of residual monomer contained in the two or more pressure-sensitive adhesive sheets 1 when the optical laminate 10B includes the two or more pressure-sensitive adhesive sheets 1 may be 16000ppm or less, 15000ppm or less, 12000ppm or less, 10000ppm or less, less than 10000ppm, 9000ppm or less, 8000ppm or less, 7500ppm or less, 7000ppm or less, 6000ppm or less, 5000ppm or less, 4000ppm or less, 3500ppm or less, and 3000ppm or less in total. The optical laminate 10 having the small total amount of the residual monomers is less likely to crack in the retardation film 2 due to the change in the ambient temperature. In addition, the total amount of the residual monomers is 16000ppm or less, which is suitable for improving the anchoring force between the retardation film 2 and the adhesive sheet 1, and particularly, the optical laminate 10B of 3500ppm or less, 2500ppm or less, or 2000ppm or less is suitable for improving the anchoring force between the retardation film 2 and the adhesive sheet 1. The lower limit of the amount is, for example, 300ppm or more, 500ppm or more, 600ppm or more, 750ppm or more, and 1000ppm or more in total. The optical laminate 10B having a lower limit in the above range is suitable for suppressing deterioration of the retardation film 2 which may occur due to exposure to irradiation of light or heat in the case where the adhesive sheet 1 is formed by irradiating light to a laminate including the retardation film 2.

The amount of the residual monomer contained in the adhesive sheet 1 varies depending on, for example, the composition of the photocurable composition used for forming the adhesive sheet 1, the kind and amount of the photopolymerization initiator possibly contained in the photocurable composition, the forming conditions and thickness of the adhesive sheet 1, and the kind and presence of post-treatment of the adhesive sheet 1. An example of the post-treatment is a surface modification treatment described later.

Fig. 3 shows another example of the optical laminate of the present embodiment. The optical laminate 10 (10C) of fig. 3 further includes a polarizing film 3. The polarizing film 3 sandwiches the adhesive sheet 1 (1A) together with the phase difference film 2. The optical laminate 10C includes, in order, a polarizing film 3, an adhesive sheet 1A, and a phase difference film 2. The optical laminate 10C further includes a polarizing film 3, an adhesive sheet 1A, a phase difference film 2, and an adhesive sheet 1B in this order. However, the position of the polarizing film 3 in the optical laminate 10 is not limited to this example. The polarizing film 3 is directly in contact with the adhesive sheet 1A. However, the polarizing film 3 and the pressure-sensitive adhesive sheet 1A may be in contact with each other with a layer having a thickness of 10 μm or less, preferably 5 μm or less. Examples of this layer are described above.

The polarizing film 3 tends to have a large dimensional change due to heat in the optical film. The dimensional change of the polarizing film 3 imparts a force that promotes the generation of cracks to the retardation film 2 contained in the same optical laminate 10. Therefore, the present invention is particularly advantageous in the case where the optical laminate 10 further includes the polarizing film 3.

< Photocurable composition >

The photocurable composition capable of forming the adhesive sheet 1 contains, for example, a monomer group containing a (meth) acrylic monomer and/or a partial polymer of the monomer group. The content of the (meth) acrylic component, that is, the (meth) acrylic monomer and its partial polymer in the photocurable composition may be 50% by weight or more, 60% by weight or more, 70% by weight or more, and further 80% by weight or more. In this case, an acrylic pressure-sensitive adhesive sheet containing a (meth) acrylic polymer and a crosslinked product thereof as a main component can be formed. However, the photocurable composition is not limited to the above examples. In the present specification, (meth) acrylic acid means acrylic acid and methacrylic acid. (meth) acrylate means acrylate and methacrylate.

Examples of the (meth) acrylic monomer are alkyl (meth) acrylates having an alkyl group having 1 to 20 carbon atoms in a side chain. The number of carbon atoms of the alkyl group may be 7 or less, 6 or less, 5 or less, and further may be 4 or less. The alkyl group may be linear or branched. Examples of alkyl (meth) acrylates are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, n-hexyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate and octadecyl (meth) acrylate. The alkyl (meth) acrylate may be n-butyl (meth) acrylate.

The content of the alkyl (meth) acrylate in the monomer group may be, for example, 40 wt% or more, 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 85 wt% or more, 90 wt% or more, and further 95 wt% or more. When the content was calculated, the weight of the partial polymer was converted to the weight of each monomer before polymerization.

The monomer group may comprise carboxyl group-containing monomers. The carboxyl group-containing monomer may be a (meth) acrylic monomer, in other words, the (meth) acrylic monomer may contain a carboxyl group-containing monomer. Examples of carboxyl group-containing monomers are (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid. The content of the carboxyl group-containing monomer in the monomer group is, for example, 0.1 to 15% by weight. The lower limit of the content may be 0.5 wt% or more, 1 wt% or more, 2.5 wt% or more, 4.5 wt% or more, 5 wt% or more, 7.5 wt% or more, and further 9.5 wt% or more. The upper limit of the content may be 13 wt% or less, 11 wt% or less, 10 wt% or less, 9.5 wt% or less, and further 7.5 wt% or less. The use of a monomer group containing a carboxyl group-containing monomer is particularly suitable for reducing the amount of residual monomer in the adhesive sheet 1. The monomer group may not contain a carboxyl group-containing monomer.

The monomer group may comprise hydroxyl-containing monomers. The hydroxyl group-containing monomer may be a (meth) acrylic monomer, in other words, the (meth) acrylic monomer may contain a hydroxyl group-containing monomer. The hydroxyl group-containing monomer can contribute to the improvement of the cohesive force of the adhesive sheet. Examples of hydroxyl group-containing monomers are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) methyl acrylate. The hydroxyl group-containing monomer is preferably 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate. The content of the hydroxyl group-containing monomer in the monomer group is, for example, 5% by weight or less, may be 4% by weight or less, 3% by weight or less, 2% by weight or less, and may be 1% by weight or less. The lower limit of the content is, for example, 0.01% by weight or more, may be 0.05% by weight or more, and may be 0.1% by weight or more. The monomer group may not contain a hydroxyl group-containing monomer.

The monomer group may contain a nitrogen atom-containing monomer. According to the studies by the present inventors, the nitrogen atom-containing monomer can contribute to the reduction of the amount of the residual monomer. The nitrogen atom-containing monomer means a monomer having at least one nitrogen atom in the molecule (1 molecule). In the present specification, monomers having a hydroxyl group and a nitrogen atom in the molecule are classified as nitrogen atom-containing monomers. Monomers having a carboxyl group and a nitrogen atom in the molecule are classified as carboxyl group-containing monomers.

The nitrogen atom-containing monomer is preferably an N-vinyl cyclic amide, (meth) acrylamide, or the like. The monomer containing nitrogen atom may be used alone or in combination of two or more.

The N-vinyl cyclic amide is preferably represented by the following formula (A).

[ Chemical formula 2]

In the formula (A), R ¹ is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (for example, an alkylene group having 3 to 5 carbon atoms or the like). The formula (a) represents that N and R ¹ are directly bonded to each other by a single bond to form a ring structure.

As the N-vinyl cyclic amide represented by the formula (A), N-vinyl-2-pyrrolidone (NVP), N-vinyl-2-piperidone, N-vinyl-2-caprolactam, N-vinyl-3-morpholinone, N-vinyl-1, 3-Oxazin-2-one, N-vinyl-3, 5-morpholinedione and the like, more preferably N-vinyl-2-pyrrolidone, N-vinyl-2-caprolactam, still more preferably N-vinyl-2-pyrrolidone.

Examples of the (meth) acrylamide include (meth) acrylamide, N-alkyl (meth) acrylamide, and N, N-dialkyl (meth) acrylamide. Examples of the N-alkyl (meth) acrylamide include N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-N-butyl (meth) acrylamide, and N-octyl acrylamide. The N-alkyl (meth) acrylamides also include (meth) acrylamides having an amino group such as dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide.

Examples of the N, N-dialkyl (meth) acrylamides include N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di-N-butyl (meth) acrylamide, and N, N-di-t-butyl (meth) acrylamide.

(Meth) acrylamides also include, for example, various N-hydroxyalkyl (meth) acrylamides. Examples of the N-hydroxyalkyl (meth) acrylamide include N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) (meth) acrylamide, and N-methyl-N-2-hydroxyethyl (meth) acrylamide.

(Meth) acrylamides also include, for example, various N-alkoxyalkyl (meth) acrylamides. Examples of the N-alkoxyalkyl (meth) acrylamide include N-methoxymethyl (meth) acrylamide and N-butoxymethyl (meth) acrylamide.

Examples of the nitrogen atom-containing monomer other than N-vinyl cyclic amide or (meth) acrylamide include amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, cyano group-containing monomers such as acrylonitrile and methacrylonitrile, and cyano group-containing monomers such as (meth) acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine and vinylAzole, vinyl isoHeterocyclic-containing monomers such as oxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth) acryloylpyrrolidone, (meth) acryloylpyrrolidine, and N-methylvinylpyrrolidone, maleimide-containing monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide, maleimide-containing monomers such as N-methylitaconyl imide, N-ethylitaconyl imide, N-butylitaconyl imide, N-octylitaconyl imide, N-2-ethylhexyl itaconyl imide, N-month Gui Jiyi-itaconyl imide, and N-cyclohexylitaconyl imide, and isocyanate-containing monomers such as N- (meth) acryloyloxymethylsuccinimide, N- (meth) acryl-6-oxohexamethylenesuccinimide, and N- (meth) acryl-8-oxooctamethylenesuccinimide, and 2- (meth) acryloyloxyethyl isocyanate.

The content of the nitrogen atom-containing monomer in the monomer group is, for example, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 18% by weight or less, 15% by weight or less, 14% by weight or less, 13% by weight or less, 12% by weight or less, 11% by weight or less, and further 10% by weight or less. The lower limit of the content is, for example, 1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more, 9% by weight or more, and further 10% by weight or more.

The monomer group may contain both carboxyl group-containing monomers and nitrogen atom-containing monomers.

The photocurable composition may contain the above monomers as a partial polymer. The partial polymer may be any of a homopolymer and a copolymer. The partial polymer can contribute to stable formation of a coating layer described later by moderately increasing the viscosity of the photocurable composition.

The photocurable composition generally contains a photopolymerization initiator. Examples of photopolymerization initiators are photo radical generators which generate radicals by visible light and/or ultraviolet light having a wavelength shorter than 450 nm.

Examples of the photopolymerization initiator include benzoin methyl ether, benzoin isopropyl ether, benzoin dimethyl ether and other benzoin ethers, anisole methyl ether and other substituted benzoin ether, 2-diethoxyacetophenone, 2-dimethoxy-2-phenylacetophenone and other substituted acetophenone, 1-hydroxycyclohexylphenyl ketone and other substituted alpha-hydroxy alkyl phenyl ketone, 2-methyl-2-hydroxy phenyl ketone and other substituted alpha-alcohol ketone, 2-naphthalenesulfonyl chloride and other aromatic sulfonyl chloride, 1-phenyl-1, 1-propanedione-2- (o-ethoxycarbonyl) -oxime and other photoactive oximes, benzophenone, benzoyl benzoic acid, benzoyl methyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4 ' -methyldiphenyl sulfide, 3', 4' -tetra (t-butylperoxycarbonyl) benzophenone and other benzophenone compounds, thioxanthone, 2-chlorothioxanthone, 2-methyl thioxanthone, isopropyl thioxanthone, 2, 4-diisopropyl thioxanthone, 2- (o-ethoxycarbonyl) -oxime, 4-dimethyl thioxanthone, 6-bis (6-methyl) -triazine, 6-bis (6-methyl-6-p-chlorotriazine and other benzophenone compounds, and the like, triazine compounds such as 2, 4-bis (trichloromethyl) -6-styryl-s-triazine, 2- (naphthalen-1-yl) -4, 6-bis (trichloromethyl) -s-triazine, 2- (4-methoxy-naphthalen-1-yl) -4, 6-bis (trichloromethyl) -s-triazine, 2, 4-trichloromethyl- (piperonyl) -6-triazine, 2, 4-trichloromethyl- (4 '-methoxystyryl) -6-triazine, triazine compounds such as 1, 2-octadione, 1- [4- (phenylthio) -,2- (O-benzoyloxime) ], oxime esters such as O- (acetyl) -N- (1-phenyl-2-oxo-2- (4' -methoxy-naphthalenyl) ethylidene) hydroxylamine, phosphine compounds such as bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, phosphine compounds such as 2,4, 6-trimethylbenzoyl diphenylphosphine oxide, phenanthrenequinone compounds such as 9, 10-quinone, camphorquinone, ethyl anthraquinone compounds, boronic acid carbazole compounds, imidazole compounds, and dititanium compounds. The photocurable composition may contain one or two or more photopolymerization initiators.

Another example of the photopolymerization initiator is a compound having a chemical structure (hereinafter, referred to as chemical structure X) represented by the following formula (1) in a molecule. According to the studies by the present inventors, the compound can contribute to the reduction of the amount of residual monomers.

[ Chemical formula 3]

R ¹ and R ² of the above formula (1) are each independently a C1-C8 alkyl group, a hydrogen atom is represented by-OH, a C1-C4 alkoxy group, -CN, -COOR ⁵¹、-OOCR⁵² or-NR ⁵³R⁵⁴ substituted C1-C4 alkyl, C3-C6 alkenyl, or-CH ₂-C₆H₄-R⁵⁵.R¹ and R ² optionally bonded to each other to form C2-C9 alkylene, or C3-C6 oxyalkylene or azaalkylene. R ⁵¹ is C1-C8 alkyl. R ⁵² is C1-C4 alkyl. R ⁵³ and R ⁵⁴ are each independently a hydrogen atom, a C1-C12 alkyl group, a C2-C4 alkyl group in which the hydrogen atom is substituted with at least one group selected from the group consisting of-OH, a C1-C4 alkoxy group, -CN and-COOR ⁵⁹, a C3-C5 alkenyl group, or a cyclohexyl group. R ⁵³ and R ⁵⁴ may be C3-C9 alkylene groups bonded to each other and optionally interrupted by-O-or-N (R ⁶⁰) -. R ⁵⁵ is C1-C4 alkyl. R ⁵⁹ is C1-C4 alkyl. R ⁶⁰ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a C1-C4 hydroxyalkyl group, -CH ₂CH₂-COOR⁶¹ or-CH ₂CH₂CN.R⁶¹ is a C1-C4 alkyl group.

X is-OR ⁵⁶ OR-NR ⁵⁷R⁵⁸.R⁵⁶ is hydrogen, -SiR ⁶² ₃, C1-C8 alkyl OR C3-C6 alkenyl. R ⁵⁷ and R ⁵⁸ are C1-C12 alkyl, C2-C4 alkyl substituted by at least one group selected from-OH, C1-C4 alkoxy, -CN and-COOR ⁶³, C3-C5 alkenyl or cyclohexyl. R ⁵⁷ and R ⁵⁸ may be C3-C9 alkylene groups bonded to each other and optionally interrupted by-O-or-N (R ⁶⁴) -. R ⁶² is C1-C6 alkyl. R ⁶³ is C1-C4 alkyl. R ⁶⁴ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a C1-C4 hydroxyalkyl group, -CH ₂CH₂-COOR⁶⁵ or-CH ₂CH₂CN.R⁶⁵ is a C1-C4 alkyl group.

The chemical structure X can be bonded to a hydrogen atom or a substituted structure of a hydrogen atom via a carbon atom represented by the formula (1).

The alkyl group, alkoxy group, alkenyl group, alkylene group, oxyalkylene group, azaalkylene group and hydroxyalkyl group described in the description of the formula (1) may be either unbranched or branched. In addition, the description of "Cn1 to Cn2" (n 1 and n2 are natural numbers) in the present specification means that the number of carbon atoms is within the range of n1 to n2, inclusive of the description of the formula (1).

R ¹ and R ² may be independently C1-C8 alkyl or C3-C6 alkenyl, or may be C1-C8 alkyl. R ¹ and R ² may be independently C1-C4 alkyl, C1-C3 alkyl, or C1-C2 alkyl. R ¹ and R ² may be methyl.

R ¹ and R ² may be the same.

X may be-OR ⁵⁶.R⁵⁶ OR a hydrogen atom OR a C1 to C8 alkyl group OR a hydrogen atom. In other words, X may be-OH.

R ¹、R² and X may be any combination of the above preferred examples.

The chemical structure X may be a structure represented by the following formula (2). In the chemical structure X of formula (2), in the case of a substituted structure in which a hydrogen atom is bonded to a carbon atom represented by a X, the substituted structure is in a para-relationship with the-COCR ¹XR² group of formula (2) with respect to the benzene ring of chemical structure X.

[ Chemical formula 4]

The photopolymerization initiator may be a compound having two or more chemical structures X within 1 molecule.

The photopolymerization initiator may be a compound represented by the following formula (3). The compound of formula (3) has two chemical structures X within 1 molecule. Two chemical structures X are located at both ends of the molecule of the photopolymerization initiator, respectively. More specifically, two chemical structures X are bonded to each other through-a-, via the carbon atom of the phenylene group indicated above.

[ Chemical formula 5]

R ¹ 'and R ²' of formula (3) independently of one another and independently of R ¹ and R ² are groups which can be taken as R ¹ and R ². R ¹ 'and/or R ²' may be the same as R ¹ and/or R ². R ¹、R²、R¹ 'and R ²' may all be the same.

X' of formula (3) is independently X of formula (1) a group that can be taken as X. X' and X may be the same.

A is-O-, -CYR ³ -, or-C (CH ₃)R⁴).

Y is hydrogen atom, -Cl, -Br, -O-R ⁷¹、-NR⁷²R⁷³, or-S-R ⁷⁴.R³ is hydrogen atom, C1-C8 alkyl, C3-C6 alkenyl, benzyl, -CH ₂-C₆H₄-R⁷⁵, or phenyl. R ⁴ is a C1-C6 alkyl group or an alkylene group bonded to a carbon atom of a phenylene group of the compound of formula (3).

R ⁷¹ is a hydrogen atom, -Si (R ⁷⁶)₃, C1-C12 alkyl, C2-C18 acyl, -CO-NH-R ⁷⁷, C2-C20 hydroxyalkyl, C2-C20 methoxyalkyl, 3-R ⁷⁸ -2-hydroxypropyl, 3- [1, 3-tetramethyl-1- [ (trimethylsilyl) oxy ] disiloxy ] propyl, 2, 3-dihydroxypropyl, or C2-C21 hydroxyalkyl groups interrupted by 1 to 9 oxygen atoms in the carbon chain, or C3-C25 alkyl groups. R ⁷² and R ⁷³ are each independently C1-C12 alkyl, C2-C4 alkyl in which a hydrogen atom is substituted with at least one group selected from the group consisting of-OH, C1-C4 alkoxy, -CN and-COOR ⁷⁹, C3-C5 alkenyl, cyclohexyl, and C7-C9 phenylalkyl. R ⁷² and R ⁷³ may be C3-C9 alkylene groups bonded to each other and optionally interrupted by-O-or-N (R ⁸⁰) -. R ⁷⁴ is C1-C18 alkyl, hydroxyethyl, 2, 3-dihydroxypropyl, cyclohexyl, benzyl, phenyl, C1-C12 alkylphenyl, -CH ₂-COOR⁸¹-CH₂CH₂-COOR⁸², or-CH (CH ₃)-COOR⁸³.R⁷⁵ is C1-C4 alkyl). R ⁷⁶ is C1-C6 alkyl. R ⁷⁷ is C1-C12 alkyl. R ⁷⁸ is C1-C18 alkoxy. R ⁷⁹ is C1-C4 alkyl. R ⁸⁰ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a benzyl group, a C1-C4 hydroxyalkyl group, -CH ₂CH₂-COOR⁸⁴, or-CH ₂CH₂CN.R⁸¹、R⁸² and R ⁸³ are each independently a C1-C18 alkyl group. R ⁸⁴ is C1-C4 alkyl.

The alkyl group, alkenyl group, acyl group, hydroxyalkyl group, methoxyalkyl group, alkoxy group, and phenylalkyl group described in the description of the formula (3) may be partially or partially branched, or may be branched.

Preferred examples of R ¹、R²、R¹ 'and R ²' in the formula (3) are the same as those of R ¹ and R ² in the description of the formula (1). The preferable example of X' in the formula (3) is the same as the preferable example of X in the above description of the formula (1). A may be-CYR ³ -. Y may be a hydrogen atom. R ³ may be a hydrogen atom. It may be that A is-CYR ³ -, and Y and R ³ are both hydrogen atoms. In other words, A may be-CH ₂ -.

R ¹、R²、R¹'、R² ', X, X', A of formula (3) may be any combination of the above preferred examples.

The photopolymerization initiator may be a compound represented by the following formula (4). The compound of formula (4) is one of the compounds of formula (3).

[ Chemical formula 6]

Specific examples of the photopolymerization initiator are shown in the following formulas (5) to (9). The photopolymerization initiator may be a compound represented by at least one chemical formula selected from the group consisting of formulas (5) to (9), a compound represented by at least one chemical formula selected from the group consisting of formulas (5) to (8), a compound represented by at least one chemical formula selected from the group consisting of formulas (5) to (7), or a compound represented by the formula (5). The compound of formula (8) is derived from a vinyl compound having a chemical structure X in a side chain. More specifically, it is an oligomer of the vinyl compound.

[ Chemical formula 7]

[ Chemical formula 8]

[ Chemical formula 9]

[ Chemical formula 10]

[ Chemical formula 11]

Photopolymerization initiators represented by the formulas (5) to (9) are commercially available as Omnirad127, esacure KIP160, esacure one, esacure KIP150, omnirad1173 (each manufactured by IGM RESINS). The photopolymerization initiator may be at least one selected from them.

Specific examples of photopolymerization initiators are 1-hydroxycyclohexyl-phenyl ketone, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and 2-hydroxy-1- (4- (4- (2-hydroxy-2-methylpropanoyl) benzyl) phenyl) 2-methylpropan-1-one. Among them, 2-hydroxy-1- (4- (4- (2-hydroxy-2-methylpropanoyl) benzyl) phenyl) 2-methylpropan-1-one is preferable. The photopolymerization initiators are commercially available as Omnirad184, omnirad819 and Omnirad127 (all made by IGM Resin Co.).

The amount of the photopolymerization initiator blended in the photocurable composition may be, for example, not more than 20 parts by weight, not more than 10 parts by weight, not more than 5.0 parts by weight, not more than 4.0 parts by weight, not more than 3.0 parts by weight, not more than 2.5 parts by weight, not more than 2.0 parts by weight, not more than 1.5 parts by weight, not more than 1.0 parts by weight, not more than 0.5 parts by weight, not more than 0.3 parts by weight, not more than 0.25 parts by weight, and not more than 0.2 parts by weight based on 100 parts by weight of the total of the monomer group and the partial polymer thereof. The lower limit of the amount of the photopolymerization initiator to be blended is, for example, 0.01 parts by weight or more, 0.03 parts by weight or more, 0.05 parts by weight or more, 0.08 parts by weight or more, 0.1 parts by weight or more, 0.13 parts by weight or more, 0.15 parts by weight or more, and further 0.18 parts by weight or more, based on 100 parts by weight of the total of the monomer group and the partial polymer thereof.

The photocurable composition may contain one or two or more photopolymerization initiators.

The photocurable composition may include a1 st photopolymerization initiator having a relatively small 1 st reaction rate, and a2 nd photopolymerization initiator having a relatively large 2 nd reaction rate. The reaction rate of each photopolymerization initiator may be determined based on the polymerization rate achieved when the monomer is polymerized using only the photopolymerization initiator. The ratio of the 2 nd reaction rate to the 1 st reaction rate is 1.1 or more as represented by the ratio of the polymerization rate A evaluated by the following measurement method using only each photopolymerization initiator. The ratio of the polymerization rate A may be 1.15 or more, or may be 1.2 or more, 1.22 or more, or 1.25 or more, or may be 1.27 or more. The upper limit of the ratio is not particularly limited, and is, for example, 3 or less. The ratio of the polymerization rate a was determined by [ polymerization rate a in the case where only the 2 nd photopolymerization initiator was used ]/[ polymerization rate a in the case where only the 1 st photopolymerization initiator was used ].

[ Measurement method ]

A mixed solution of 99 parts by weight of n-butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate as monomers and 0.1 part by weight of a photopolymerization initiator to be evaluated was irradiated with ultraviolet light to prepare a monomer slurry in which the above monomers were partially polymerized. The irradiation of ultraviolet rays was performed until the viscosity of the mixed solution at 30℃reached 20 Pa.s. Next, a coating layer of 20 μm in thickness formed from the produced monomer slurry was formed between a pair of polyethylene terephthalate (PET) pellets each having a thickness of 75 μm. Next, the coating layer was irradiated with ultraviolet rays having an LED having a peak wavelength of 340nm±10nm as a light source from the PET sheet-making side of one side. The illuminance and irradiation time of the irradiated ultraviolet were set to 4mW/cm ² and 1200 seconds, respectively. The polymerization rate of the monomer measured on the coating layer after the photo-curing by irradiation with ultraviolet rays was determined as a polymerization rate a.

According to the studies by the present inventors, the combination of the 1 st and 2 nd photopolymerization initiators affects the state of polymerization when forming the adhesive sheet, and can contribute to the reduction of the amount of residual monomers. The composition of the monomer syrup used for evaluating the polymerization rate a is known as a general composition for forming an acrylic pressure-sensitive adhesive sheet. The ultraviolet irradiation conditions are suitable for evaluating the polymerization state.

The polymerization rate a of the 1 st photopolymerization initiator may be 80% or less, 79% or less, and further 78% or less. The lower limit of the polymerization rate a is, for example, 65% or more, 66% or more, 67% or more, 68% or more, 69% or more, and further 70% or more.

The polymerization rate a of the 2 nd photopolymerization initiator may be 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, and further 99% or more. The upper limit of the polymerization rate A is, for example, 99.9% or less, and may be 99.5% or less.

The polymerization ratio A of the 1 st photopolymerization initiator and the polymerization ratio A of the 2 nd photopolymerization initiator may satisfy the above ranges at the same time. For example, the polymerization rate a of the 1 st photopolymerization initiator may be 80% or less, and the polymerization rate a of the 2 nd photopolymerization initiator may be 90% or more.

Examples of the 1 st and 2 nd photopolymerization initiators are benzoyl ethers, substituted acetophenones, alpha-hydroxyacetophenone, substituted alpha-ketols, aromatic sulfonyl chlorides, photoactive oximes benzophenone compounds, thioxanthone compounds, triazine compounds, oxime ester compounds, phosphine compounds, quinone compounds, boric acid ester compounds, carbazole compounds, imidazole compounds and titanocene compounds.

The 1 st photopolymerization initiator is preferably an alpha-hydroxyacetophenone compound. The 1 st photopolymerization initiator as an α -hydroxyacetophenone compound is particularly suitable for increasing the molecular weight of the polymer in combination with the 2 nd photopolymerization initiator. The number of the α -hydroxyacetophenone structures contained in the 1 st photopolymerization initiator in the 1 st molecule is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

A specific example of the 1 st photopolymerization initiator is 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methylpropanediol. The photopolymerization initiator is an α -hydroxyacetophenone compound and is commercially available as Omnirad2959 (IGM RESINS).

The 2 nd photopolymerization initiator is not limited, and may be an α -hydroxyacetophenone compound. The 2 nd photopolymerization initiator as an α -hydroxyacetophenone compound is particularly suitable for increasing the molecular weight of the polymer in combination with the 1 st photopolymerization initiator, particularly the 1 st photopolymerization initiator as an α -hydroxyacetophenone compound. The number of the α -hydroxyacetophenone structures contained in the 1 st molecule of the 2 nd photopolymerization initiator is, for example, 1 to 3, preferably 1 or 2, and more preferably 2.

The 2 nd polymerization initiator may be the above-mentioned compound having the chemical structure X in the molecule, including the preferred mode.

The photocurable composition may contain one or more of the 1 st photopolymerization initiator. The photocurable composition may contain one or two or more of the 2 nd photopolymerization initiators.

The ratio of the compounding amount X1 of the 1 st photopolymerization initiator to the compounding amount X2 of the 2 nd photopolymerization initiator is, for example, 5:1 to 1:5 in terms of weight ratio, and may be 4:1 to 1:4, 3:1 to 1:3, 2:1 to 1:2, and may be 1.5:1 to 1:1.5.

The photocurable composition may include a crosslinking agent. Examples of the crosslinking agent are polyfunctional monomers having two or more polymerizable functional groups in 1 molecule. The multifunctional monomer may be a (meth) acrylic monomer. Examples of polyfunctional monomers are monomers having two or more c=c bonds in 1 molecule, and monomers having one or more c=c bonds and one or more epoxy groups, aziridinyl groups in 1 molecule,Monomers having polymerizable functional groups such as an oxazoline group, a hydrazine group, and a hydroxymethyl group. The polyfunctional monomer is preferably a monomer having two or more c=c bonds in 1 molecule.

Examples of the polyfunctional monomer are polyfunctional acrylates (e.g., an ester compound of a polyhydric alcohol and (meth) acrylic acid) such as (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 2-ethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 9-nonanediol diacrylate (NDDA), 1, 12-dodecanediol di (meth) acrylate, trimethylol propane tri (meth) acrylate, and tetramethylol methane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di (meth) acrylate, and hexyl di (meth) acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, more preferably trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate.

The amount of the crosslinking agent to be blended varies depending on the molecular weight, the number of functional groups, etc., and is, for example, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and further 0.5 parts by weight or less, based on 100 parts by weight of the total of the monomer group and the partial polymer thereof. The lower limit of the amount is, for example, 0.01 parts by weight or more, and further may be 0.05 parts by weight or more.

The photocurable composition may contain additives other than the above. Examples of additives are chain transfer agents, silane coupling agents, viscosity modifiers, tackifiers, plasticizers, softeners, age resistors, fillers, colorants, antioxidants, surfactants, antistatic agents, and ultraviolet absorbers.

The amount of the silane coupling agent to be blended is, for example, 3 parts by weight or less, may be 2 parts by weight or less, 1 part by weight or less, and may be 0.5 part by weight or less, per 100 parts by weight of the total of the monomer group and the partial polymer thereof. The lower limit of the amount is, for example, 0.1 part by weight or more, and further may be 0.2 part by weight or more. The photocurable composition may not contain a silane coupling agent.

The content of the solvent in the photocurable composition is, for example, 5% by weight or less, and may be 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, and further may be 0.5% by weight or less. The photocurable composition may contain substantially no solvent. Substantially not containing a solvent means that a solvent derived from an additive or the like is allowed to be contained at a content of, for example, 0.1 wt% or less, preferably 0.05 wt% or less, and more preferably 0.01 wt% or less.

The viscosity of the photocurable composition is preferably 5 to 100 poise. The photocurable composition having the viscosity in the above range is particularly suitable for forming a coating layer described later.

The polymerization rate of the monomer group in the adhesive sheet 1 is preferably 95% or more. The polymerization rate may be 96% or more, 97% or more, 98% or more, and further 99% or more.

The gel fraction of the pressure-sensitive adhesive sheet 1 is, for example, 50% or more, 75% or more, 80% or more, and 85% or more.

The thickness of the pressure-sensitive adhesive sheet 1 may be, for example, 70 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, and further 20 μm or less. The lower limit of the thickness is, for example, 2 μm or more, may be 5 μm or more, and may be 10 μm or more.

The adhesive sheet 1 may have a surface (hereinafter, "modified surface") 4 to which a surface modification treatment is applied. Typically, the surface modification treatment is a treatment using active energy rays. The surface modification treatment may be at least one selected from corona treatment, plasma treatment, excimer UV light treatment and flame treatment, and may be corona treatment and/or plasma treatment, or corona treatment. Each surface modification treatment may be performed by a corresponding known treatment device.

The surface modification treatment condition for the corona treatment is represented by the discharge amount, and is, for example, 0.6 to 100kJ/m ². The lower limit of the discharge amount can be more than 1kJ/m ², more than 2kJ/m ², more than 5kJ/m ², more than 7kJ/m ², 10kJ/m ² or more, 13kJ/m ² or more, 15kJ/m ² or more, 20kJ/m ² or more, 25kJ/m ² or more, 30kJ/m ² or more, and further 35kJ/m ² or more. The upper limit of the discharge amount can be below 70kJ/m ², below 60kJ/m ², below 50kJ/m ², below 45kJ/m ², 40kJ/m ² or less, 30kJ/m ² or less, 20kJ/m ² or less, and further 18kJ/m ² or less.

The pressure-sensitive adhesive sheet 1 of fig. 1 has a modified surface 4 on the retardation film 2 side. This method is particularly suitable for improving the anchoring force of the adhesive sheet 1 to the retardation film 2. The pressure-sensitive adhesive sheet 1 may have the modified surface 4 on the side opposite to the retardation film 2 side, or may have the modified surface 4 on both sides of the retardation film 2 side and the opposite side.

The anchoring force of the pressure-sensitive adhesive sheet 1 to the retardation film 2 may be 10N/25mm or more, 12N/25mm or more, 13N/25mm or more, 14N/25mm or more, 15N/25mm or more, 16N/25mm or more, 17N/25mm or more, and further 18N/25mm or more. The upper limit of the anchoring force is, for example, 50N/25mm or less, and may be 30N/25mm or less.

Improving the anchoring force of the adhesive sheet 1 to the retardation film 2 can help to suppress peeling between the adhesive sheet 1 and the retardation film 2, for example. The optical laminate with the peeling suppressed is suitable for suppressing degradation of image quality in an image display device that may be used in a severe environment for a long period of time, for example.

The anchoring force of the adhesive sheet 1 to the retardation film 2 can be measured by the following method. The laminate including the retardation film 2 and the pressure-sensitive adhesive sheet 1 was cut out to have a width of 25mm×a length of 150mm, and a test piece was produced. Next, the entire surface of the retardation film 2 provided in the test piece was laminated with a stainless steel test plate via a double-sided tape, and a 2kg roller was reciprocated 1 time to press the film. Next, the pressure-sensitive adhesive sheet 1 provided in the test piece was laminated with the evaluation sheet, and a 2kg roller was reciprocated 1 time to press the two sheets together. The evaluation sheet has dimensions of 30mm in width by 150mm in length, and is not particularly limited as long as it is not peeled off from the adhesive sheet 1 in the test. As the evaluation sheet, for example, an ITO film (125 Tetoraito OES (manufactured by Tail pool Co., ltd.) or the like can be used. Next, using a commercially available tensile tester, the adhesive sheet 1 was peeled from the retardation film 2 at a peeling angle of 180 ° and a stretching speed of 300 mm/min while holding the sheet for evaluation, and the average value of the peeling forces at this time was determined as the anchoring force of the adhesive sheet 1 to the retardation film 2. The above test was performed in an atmosphere of 23.+ -. 5 ℃.

(Retardation film)

As the retardation film 2, a film obtained by stretching a polymer film, or a film obtained by aligning and fixing a liquid crystal material can be used. The retardation film 2 has birefringence in the in-plane and/or thickness direction, for example.

The retardation film 2 includes an antireflection retardation film (see japanese patent application laid-open nos. 2012-133303 [0221], [0222], [0228 ]), a retardation film for viewing angle compensation (see japanese patent application laid-open nos. 2012-133303 [0225], [0226 ]), a tilt orientation retardation film for viewing angle compensation (see japanese patent application laid-open nos. 2012-133303 [0227 ]), and the like.

The specific constitution of the retardation film 2, for example, the retardation value, the arrangement angle, the three-dimensional birefringence, whether it is a single layer or a plurality of layers, and the like are not particularly limited, and a known retardation film can be used.

The thickness of the retardation film 2 is, for example, 30 to 200. Mu.m, preferably 40 to 150. Mu.m.

The retardation film 2 may include, for example, a 1/4 wave plate and/or a 1/2 wave plate obtained by aligning and immobilizing a liquid crystal material.

The retardation film 2 containing the cycloolefin polymer is particularly prone to cracking. In addition, in the case of the uniaxially stretched film, the crack is more likely to occur in the retardation film 2 as the stretched film than in the case of the biaxially stretched film. Therefore, the present invention is particularly advantageous in the case where the retardation film 2 contains a cycloolefin polymer and in the case of a uniaxially stretched film.

The retardation film 2 may have a modified surface. The retardation film 2 of fig. 1 has a modified surface 5 on one side of the pressure-sensitive adhesive sheet 1. This method is particularly suitable for improving the anchoring force between the retardation film 2 and the adhesive sheet 1. Examples of the surface modification treatment including the preferred examples are as described above.

Examples of residual monomers that may be contained in the retardation film 2 and the optical laminate 10 are (meth) acrylic monomers. Examples of the (meth) acrylic monomer are the same as those contained in the photocurable composition capable of forming the adhesive sheet 1.

(Polarizing film)

The polarizing film 3 includes a polarizer. Typically, the polarizing film 3 includes a polarizer and a protective film (transparent protective film). The protective film is disposed in contact with, for example, a principal surface (surface having the widest area) of the polarizer. The polarizer may be disposed between the two protective films. The protective film may be disposed on at least one surface of the polarizer.

Examples of the polarizer include, but are not limited to, a polarizer obtained by unidirectionally stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, an ethylene-vinyl acetate copolymer partially saponified film, a dehydrated polyvinyl alcohol product, and a polyene oriented film such as a desalted polyvinyl chloride product. Typically, the polarizer is formed of a dichroic substance such as polyvinyl alcohol film (the polyvinyl alcohol film includes an ethylene-vinyl acetate copolymer-based partially saponified film).

The thickness of the polarizer is not particularly limited, and may be, for example, 80 μm or less, 50 μm or less, 30 μm or less, 28 μm or less, 25 μm or less, 20 μm or less, and further 18 μm or less. The lower limit of the thickness of the polarizer is not particularly limited, and may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, and further 15 μm or more. The thin polarizer (for example, having a thickness of 20 μm or less) is suppressed in dimensional change due to heat, and can contribute to improvement in durability of the optical laminate, particularly durability at high temperature. Further, since the larger the thickness of the polarizer is, the larger the dimensional change by heat tends to be, for example, in the case where the thickness of the polarizer exceeds 20 μm, particularly, in the case of 25 μm or more, the present invention is particularly advantageous.

As a material of the protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like can be used. Specific examples of such thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the protective film may be a thermosetting resin such as (meth) acrylic, urethane, acrylic urethane, epoxy, or silicone, or an ultraviolet curable resin. In the case where the polarizing film has two protective films, the materials of the two protective films may be the same or different from each other. For example, a protective film made of a thermoplastic resin may be bonded to one principal surface of the polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet-curable resin may be bonded to the other principal surface of the polarizer. The protective film may contain one or more arbitrary additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like.

The thickness of the protective film can be appropriately determined, and is generally 5 to 200 μm, preferably 10 to 80 μm, in view of handling properties such as strength and handling properties, film properties, and the like.

The polarizer and the protective film are usually adhered together via an aqueous adhesive or the like. Examples of the aqueous adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex, aqueous polyurethane, aqueous polyester, and the like. Examples of the adhesive other than the above-mentioned adhesive include an ultraviolet-curable adhesive, an electron beam-curable adhesive, and the like. The adhesive for electron beam curable polarizing plates exhibits suitable adhesion to various protective films. The adhesive may also contain a metal compound filler.

The protective film may be provided with a hard coat layer on a surface thereof facing the surface to which the polarizer is bonded, and may be subjected to treatments for the purpose of antireflection, antiblocking, diffusion, antiglare, and the like.

Polarizing film 3 may be a circular polarizing film.

The thickness of the polarizing film 3 is, for example, 500 μm or less, 300 μm or less, 200 μm or less, 100 μm or less, and further 60 μm or less. The lower limit of the thickness is, for example, 10 μm or more, may be 25 μm or more, and may be 40 μm or more.

The optical laminate 10 may include layers other than the pressure-sensitive adhesive sheet 1, the retardation film 2, and the polarizing film 3. Examples of such layers are an optical film other than the retardation film 2 and the polarizing film 3, an undercoat layer, an antistatic layer, a protective layer, a coating layer, a hard coat layer, a glass cover, an adhesive sheet other than the adhesive sheet 1, and a base sheet that can be used for formation of the adhesive sheet 1.

[ Method for producing optical laminate ]

The optical laminate 10 can be formed by laminating other layers such as the pressure-sensitive adhesive sheet 1, the retardation film 2, and the polarizing film 3, if necessary. The pressure-sensitive adhesive sheet 1 can be formed by, for example, irradiating the 1 st laminate 15 sequentially including the base sheet 21, the coating layer 22 containing the photocurable composition, and the release liner 23 with light 14 (see fig. 4A to 4C). The coating layer 22 is cured by irradiation with light 14, and becomes the adhesive sheet 1.

In the example of fig. 4A, light 14 is irradiated from one side of the base sheet 21. At this time, the light 14 passes through the base sheet 21 and reaches the coating layer 22. However, the light 14 may be irradiated from one side of the release liner 23, or may be irradiated from both sides of the release liner 23 and the base material sheet 21 (fig. 4B). The formed adhesive sheet 1 is sandwiched between the base sheet 21 and the release liner 23 to form a part of the 2 nd laminate 16 until the release liner 23 is peeled off.

An example of the base material of the release liner 23 (hereinafter, "liner base material") is a resin film. Examples of the resin that can be contained in the backing material are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfones, polycarbonates, polyamides, polyimides, polyolefins, (meth) acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylates, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

The release liner 23 may have the same degree of transmittance of the light 14 as the base sheet 21 or may have the same degree of transmittance of the light 14.

The thickness of the release liner 23 may be, for example, 10 to 200. Mu.m, and 25 to 150. Mu.m.

The release liner 23 may be provided with a layer other than the liner base material. The release liner 23 may be provided with a release layer. The release liner 23 includes, for example, a liner base material and a release layer formed on one surface of the liner base material. The release liner 23 may be used so that the release layer is on the coating layer 22 side.

Typically, the release layer is a cured layer of a release agent composition comprising a release agent. As the release agent, various release agents such as silicone release agents, fluorine release agents, long-chain alkyl release agents, fatty acid amide release agents, and silica powder can be used. The release liner 23 may include a cured layer (hereinafter, "silicone release layer") of a release agent composition containing a silicone release agent as a main component. The silicone release layer is particularly suitable for both adhesion to and release from the adhesive sheet 1. In the present specification, the main component means a component having the largest content.

The silicone release agent is, for example, an addition reaction type, a condensation reaction type, an ultraviolet ray curing type, an electron beam curing type, a solvent-free type or other curing type silicone material, and is preferably an addition reaction curing type silicone material. The addition reaction curable silicone material is particularly suitable for forming a release layer that combines adhesion to the adhesive sheet 1 and releasability. The curable silicone material may be a silicone modified resin obtained by introducing a reactive silicone into an organic resin such as urethane, epoxy, or alkyd resin by graft polymerization or the like.

Examples of addition reaction curable silicone materials are polyorganosiloxanes having vinyl groups or alkenyl groups (alkenyl groups) in the molecule. The addition reaction curable silicone material may not have a hydrosilyl group. Examples of alkenyl are 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl and 11-dodecenyl. Examples of the polyorganosiloxane include a polyalkylalkyl siloxane such as polydimethylsiloxane, polydiethyl siloxane and polymethyl ethyl siloxane, a polyalkylaryl siloxane, and a copolymer of a plurality of Si atom-containing monomers such as poly (dimethylsiloxane-diethylsiloxane). The polyorganosiloxane is preferably is polydimethylsiloxane.

The release agent composition containing a silicone-based release agent as a main component (hereinafter, "silicone release agent composition") generally contains a crosslinking agent. Examples of crosslinking agents are polyorganosiloxanes having hydrosilyl groups. The crosslinking agent may have two or more hydrosilyl groups in one molecule.

The silicone release agent composition may also contain a curing catalyst. An example of a curing catalyst is a platinum-based catalyst. Examples of platinum-based catalysts are chloroplatinic acid, olefin complexes of platinum, olefin complexes of chloroplatinic acid. The amount of the platinum-based catalyst used is, for example, 10 to 1000ppm (calculated as platinum on a weight basis) based on the total solid content of the composition.

The silicone release agent composition may also contain additives. Examples of the additive are a peeling control agent and an adhesion improving agent. Examples of the release control agent are unreacted silicone resins, and more specific examples are organosiloxanes such as octamethyl cyclotetrasiloxane and MQ resins. The amount of the peeling controlling agent and the adhesion improving agent is, for example, 1 to 30% by weight in total based on the total solid content of the composition. Other examples of additives are fillers, antistatic agents, antioxidants, ultraviolet absorbers, plasticizers and colorants. The amount of the other additives is, for example, 10% by weight or less in total with respect to the total solid content of the composition.

The silicone release agent composition may also comprise an organic solvent. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, n-hexane and n-heptane, aromatic solvents such as toluene and xylene, ester solvents such as ethyl acetate and methyl acetate, ketone solvents such as acetone and methyl ethyl ketone, and alcohol solvents such as methanol, ethanol and butanol. Two or more organic solvents may be contained. The amount of the organic solvent is preferably 80 to 99.9% by weight of the silicone release agent composition.

The release layer can be formed, for example, by heating and drying a coating film containing the release agent composition formed on the substrate. The release agent composition may be applied by various coating methods such as roll coating, roll lick coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, die lip coating, and die coating. The heating and drying may be, for example, hot air drying. The heating temperature and time vary depending on the heat resistance of the backing material, and are usually about 80 to 150 ℃ and about 10 seconds to 10 minutes. If necessary, irradiation with active energy rays such as ultraviolet rays may be used in combination.

The thickness of the release layer is, for example, 10 to 300nm. The upper limit of the thickness may be 200nm or less, 150nm or less, 120nm or less, 110nm or less, 100nm or less, less than 100nm, 90nm or less, 80nm or less, 70nm or less, less than 70nm, and further 65nm or less. The lower limit of the thickness may be 15nm or more, 20nm or more, 25nm or more, 30nm or more, 35nm or more, 40nm or more, 45nm or more, and further 50nm or more.

The release liner 23 may be a single sheet or a long sheet.

An example of the base sheet 21 is a resin film. Examples of the resin contained in the base material sheet 21 are the same as examples of the resin that can be contained in the backing material.

The base sheet 21 preferably has excellent light transmittance to the light 14.

The thickness of the base sheet 21 may be, for example, 10 to 200 μm or 25 to 150 μm.

The base sheet 21 may have a release layer on the side of the coating layer 22. Examples of the release layer and the method for producing the same that can be provided for the base sheet 21 are the same as examples of the release layer and the method for producing the same that can be provided for the release liner 23. The release liner 23 and the base sheet 21 may be provided with release layers. In this case, the release layers of both may be formed of a release agent composition containing the same release agent as a main component. The thickness of the release layer may be different between the two, and for example, the release layer provided in the base sheet 21 may be thicker.

The base sheet 21 may be a sheet having a larger peeling force from the adhesive sheet 1 than the release liner 23.

The base sheet 21 may be a single sheet or a long sheet.

The 1 st laminate 15 can be formed, for example, by forming the coating layer 22 on the base sheet 21 (or the release liner 23) and disposing the release liner 23 (or the base sheet 21) on the formed coating layer 22. The 1 st layered body 15 may be formed by coating the photocurable composition so as to flow into a space between the base material sheet 21 and the release liner 23 which are held at a predetermined interval so as to face each other on the principal surface.

The coating layer 22 may be formed by various coating methods such as roll coating, roll lick coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, die lip coating, and die coating.

The thickness of the coating layer 22 may be adjusted corresponding to the thickness of the adhesive sheet 1 of interest.

The light 14 irradiated to the 1 st laminate 15 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light 14 may contain light having a wavelength in the same region as the absorption wavelength of the photopolymerization initiator contained in the photocurable composition. The light 14 obtained by cutting short wavelength light having a wavelength of 300nm or less by a filter or the like can be irradiated, and the short wavelength light cut is suitable for suppressing degradation of the base sheet 21 and/or the release liner 23 due to the light 14. The light source of the light 14 is, for example, an illumination device provided with an ultraviolet irradiation lamp. Examples of ultraviolet irradiation lamps are ultraviolet LEDs, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, microwave-excited mercury lamps, black light lamps, chemical lamps, germicidal lamps, low-pressure discharge mercury lamps, and excimer lasers. Two or more ultraviolet irradiation lamps may be combined.

The irradiation of light 14 may be continuous or intermittent.

The irradiation intensity of the light 14 is, for example, 1 to 20mW/cm ². The irradiation time of the light 14 is, for example, 5 minutes to 5 hours. The cumulative amount of light 14 to the 1 st laminate 15 is, for example, 100 to 5000mJ/cm ².

Then, the release liner 23 is peeled from the 2 nd laminate 16 to expose the surface of the adhesive sheet 1. The optical laminate 10 can be formed by disposing the retardation film 2 on the exposed surface of the pressure-sensitive adhesive sheet 1. The exposed surface of the pressure-sensitive adhesive sheet 1 may be subjected to a surface modification treatment before the retardation film 2 is disposed.

The optical laminate of the present embodiment may be distributed and stored in the form of a wound body obtained by winding a band-shaped optical laminate, or in the form of a sheet-shaped optical laminate, for example.

Typically, the optical layered body of the present embodiment can be used for an image display device. The image display device may be formed by joining the optical laminate 10 to an image display panel, for example. The bonding is performed by, for example, the adhesive sheet 1. The image display device may be an organic EL display or a liquid crystal display. However, the image display device is not limited to the above example. The image display device may be an Electroluminescent (EL) display, a Plasma Display (PD), a field emission display (FED: field Emission Display), or the like. The image display device may be an image display device for use that may be exposed to a high-temperature environment, and typically may be an image display device for use in a vehicle. However, the application of the image display device is not limited. The image display device can be used for various applications such as home appliance applications and Public Information Display (PID) applications.

Examples

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples shown below.

[ Preparation of polarizing film ]

(Polarizing film A)

Between rolls having different speed ratios, a polyvinyl alcohol film having a thickness of 80 μm was stretched to 3 times while being dyed in an iodine solution having a concentration of 0.3% at a temperature of 30℃for 1 minute. Next, the sheet was stretched to a total stretching ratio of 6 times while immersed in an aqueous solution containing boric acid at a concentration of 4% and potassium iodide at a concentration of 10% for 0.5 minutes at a temperature of 60 ℃. Next, the resultant was immersed in an aqueous solution containing potassium iodide at a concentration of 1.5% and having a temperature of 30 ℃ for 10 seconds, and then washed, and dried at 50 ℃ for 4 minutes, whereby a polarizer having a thickness of 18 μm was obtained. A30 μm thick transparent protective film made of a modified acrylic polymer having a lactone ring structure was bonded to one surface of the polarizer via a polyvinyl alcohol adhesive. Further, a transparent protective film having a thickness of 47 μm, in which a hard coat layer (HC) was formed on a cellulose triacetate film (trade name "KC4UY", manufactured by konicar, inc.) was bonded to the other surface of the polarizer via a polyvinyl alcohol adhesive. The polarizing film a was produced by drying in an oven set at 70 ℃ for 5 minutes. Further, the surface of the polarizing film a on the transparent protective film side formed of the modified acrylic polymer was subjected to corona treatment at a discharge amount of 63W/(m ² ·min).

(Polarizing film B)

Except that the stretching conditions were changed, a polarizing plate having a thickness of 28 μm was obtained in the same manner as in the production of the polarizing film a. A30 μm thick transparent protective film made of a modified acrylic polymer having a lactone ring structure was bonded to one surface of the polarizer with a polyvinyl alcohol adhesive. Further, a 40 μm thick transparent protective film having a hard coat layer (HC) formed on a cellulose triacetate film (trade name "KC4UY", manufactured by Konikoku Meida) was bonded to the other surface of the polarizer by a polyvinyl alcohol adhesive. The polarizing film B was produced by performing heat drying in an oven set at 70 ℃ for 5 minutes. Further, the surface of the polarizing film B on the transparent protective film side formed of the modified acrylic polymer was subjected to corona treatment at a discharge amount of 63W/(m ² ·min).

[ Preparation of retardation film ]

Biaxially oriented polypropylene films (trade name "TORAYFAN" BO 2570A-5, thickness 60 μm, manufactured by Toli) were laminated on both sides of a polymer film (trade name "Zeonor ZF14-100, thickness 100 μm, manufactured by Japanese Rui Weng Zhushi Co., ltd.) containing a resin obtained by hydrogenating a ring-opened polymer of a norbornene-based monomer via an acrylic pressure-sensitive adhesive layer (thickness 15 μm). Then, the film was stretched to 1.38 times in an air circulation type constant temperature oven at 146.+ -. 1 ℃ by a roll stretcher, thereby producing a retardation film having a thickness of 108. Mu.m.

[ Production of monomer slurry ]

Synthesis example 1

99 Parts by weight of n-Butyl Acrylate (BA), 1 part by weight of 4-hydroxybutyl acrylate (HBA) and 10 parts by weight of Acrylic Acid (AA), and 0.1 part by weight of Omnirad184 (1-hydroxycyclohexyl-phenyl ketone, IGM RESINS) as a photopolymerization initiator were put into a four-necked flask, and ultraviolet rays were irradiated in a nitrogen atmosphere, thereby obtaining a partially photopolymerized monomer syrup A1. The irradiation with ultraviolet rays was performed until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No.5 rotor, 10rpm, measurement temperature 30 ℃) reached about 20 Pa.s.

Synthesis example 2

Monomer slurries A2 to a14 were prepared in the same manner as monomer slurry A1 except that the monomers used were changed as shown in table 1.

TABLE 1

The abbreviations in table 1 are as follows. Omnirad2959 and Omnirad127 are α -hydroxyacetophenone compounds.

BA n-butyl acrylate

HBA 4-hydroxybutyl acrylate

AA acrylic acid

NVP N-vinyl-2-pyrrolidone

Omnirad 184. 1-hydroxycyclohexyl-phenyl ketone (Omnirad 184, manufactured by IGM Resin Co., ltd.)

Omnirad651, 2-dimethoxy-1, 2-diphenylethan-1-one (manufactured by Omnirad651, IGM RESINS Co., ltd.)

Omnirad127 2-hydroxy-1- (4- (4- (2-hydroxy-2-methylpropanoyl) benzyl) phenyl) 2-methylpropan-1-one (Omnirad 127, manufactured by IGM Resin Co., ltd.)

Omnirad2959 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methylpropionne (Omnirad 2959, manufactured by IGM Resin Co., ltd.)

[ Production of photocurable composition ]

The monomer slurry, the crosslinking agent, and the silane coupling agent were mixed so as to have the compositions shown in table 2 below, to obtain photocurable compositions C1 to C14. The crosslinking agent used was 1, 9-nonanediol diacrylate (NDDA). As the silane coupling agent, an epoxy group-containing silane coupling agent (KBM-403, made by Xinyue silicone) was used.

TABLE 2

[ Production of adhesive sheet ]

Production example 1 production of Release liner A

30 Parts BY weight of addition reaction curable silicone (LTC 761 containing hexenyl polyorganosiloxane, 30% BY weight of toluene solution, toray Dow Corning), 0.9 part BY weight of release control agent (BY 24-856, toray Dow Corning) containing unreacted silicone resin, 2 parts BY weight of curing catalyst (SRX 212 containing platinum catalyst, toray Dow Corning), and toluene/hexane mixed solvent (volume ratio 1:1) as a diluent were mixed to obtain an organosilicon release agent composition. The concentration of the silicone solid component in the release agent composition was 1.0% by weight. Next, a release liner a having a release layer (thickness 60 nm) on one side was prepared by applying a release agent composition to one side of a liner substrate (Lumirror XD500P as a polyester film, thickness 75 μm) with a wire bar and heating at 130 ℃ for 1 minute.

Production example 2 production of Release liner B

A release liner B having a release layer (thickness 120 nm) on one surface was produced in the same manner as in production example 1, except that the thickness of the release agent composition applied to the liner base material was changed.

Example 1

The photocurable composition C1 was applied to one surface of the release liner a produced in production example 1 by an applicator to form a coating layer. Next, the release liner B produced in production example 2 was disposed on the formed coating layer, and a1 st laminate was obtained. The release liners A, B are each disposed so that the release layer and the coating layer are in contact with each other. Then, ultraviolet rays (Black light source) were irradiated from the release liner a side of the 1 st laminate under irradiation intensity of 2.5mW/cm ² and irradiation time of 640 seconds, and the coating layer was photo-cured, thereby forming a2 nd laminate composed of the release liner a, the adhesive sheet (thickness 20 μm) and the release liner B. Then, the release liner B was peeled from the 2 nd laminate, and the retardation film having been corona-treated on both sides was bonded to the exposed surface of the pressure-sensitive adhesive sheet formed by the peeling. Next, another pressure-sensitive adhesive sheet formed in the same manner as described above was bonded to the exposed surface of the retardation film, to obtain an optical laminate having a laminated structure of release liner a/pressure-sensitive adhesive sheet/retardation film/pressure-sensitive adhesive sheet/release liner a. Then, the release liner a on one side is peeled from the optical laminate, and the prepared polarizing film a or polarizing film B is bonded to the exposed adhesive sheet. The bonding is performed such that the adhesive sheet is in contact with a transparent protective film made of a modified acrylic polymer in the polarizing film A, B. Thus, an optical laminate a (thickness of a polarizer was 18 μm) having a laminate structure of polarizing film a/adhesive sheet/retardation film/adhesive sheet/release liner a, and an optical laminate B (thickness of a polarizer was 28 μm) having a laminate structure of polarizing film B/adhesive sheet/retardation film/adhesive sheet/release liner a were obtained.

Example 2

An optical laminate a and an optical laminate B of example 2 were obtained in the same manner as in example 1, except that the photocurable composition C2 was used in place of the photocurable composition C1, and a corona treatment (discharge amount 61W/(m ² ·min)) was applied to the surface of each adhesive sheet on the phase difference film side before bonding to the phase difference film.

(Example 3. About.10)

Optical laminates a and B of examples 3 to 10 were obtained in the same manner as in example 1, except that each of the photocurable compositions C3 to C11 was used instead of the photocurable composition C1.

Example 11

An optical laminate a and an optical laminate B of example 11 were obtained in the same manner as in example 2, except that the photocurable composition C11 was used instead of the photocurable composition C2.

(Comparative example 1 to 4)

Optical laminates a and B of comparative examples 1 to 4 were obtained in the same manner as in example 1, except that the photocurable compositions C5 and C12 to 14 were used instead of the photocurable composition C1.

[ Polymerization Rate ]

The polymerization rate of each adhesive sheet formed in examples and comparative examples was calculated from the weight change of the adhesive sheet before and after heat drying at 130 ℃. Specifically, the weight of the adhesive sheet immediately after the release liner a and the release liner B were peeled from the 2 nd laminate was represented by W ₀ (weight before drying), and the weight of the adhesive sheet at the time of cooling at room temperature (23 ℃) for about 20 minutes after the heating was represented by W ₁ (weight after drying), which was obtained by the formula: polymerization ratio (%) =w ₁/W₀ ×100.

[ Amount of residual monomer ]

The amounts of residual monomers in each of the adhesive sheets formed in examples and comparative examples were evaluated by GC analysis. The apparatus and measurement conditions used for GC analysis are shown below.

Use device GC7890A (Agilent Technologies)

HP-1 (Agilent Technologies)

Detector-Hydrogen Flame Ionization Detector (FID)

Injection port temperature 250 °c

The temperature conditions were measured by the following steps (1) to (4). (1) maintaining at 0 ℃ for 3 minutes, (2) raising the temperature at 10 ℃ per minute at a temperature raising rate, (3) raising the temperature at 20 ℃ per minute after reaching 120 ℃, and (4) maintaining at 300 ℃

Sample preparation method 0.05g of the sample (adhesive sheet) was collected in a screw bottle, and 2.5mL of ethyl acetate was added thereto, followed by shaking overnight. The obtained solution was filtered by a 0.45 μm membrane filter, and 1. Mu.L of the filtrate was injected into GC for analysis.

[ Anchoring force ]

Using each of the optical laminates a produced in examples and comparative examples, the anchoring force of the adhesive sheet to the retardation film was evaluated by the method described above. The double-sided tape was used under the trade name "No.531" manufactured by Ridong electric Co., ltd. As the stainless steel test plate, SUS304 plate (width 40 mm. Times.length 120 mm) was used. The evaluation sheet used was an ITO film (125 Tetoraito OES manufactured by Tail pool Industrial Co., ltd.). A tensile tester (manufactured by Shimadzu corporation) of Autograph SHIMAZU AG-I10 KN was used.

[ Easiness of crack formation ]

For each of the optical laminates a and B of examples and comparative examples, the ease of occurrence of cracks in the retardation film was evaluated as follows. The optical laminate was cut into a rectangular shape of 300mm×210mm to prepare test pieces. Then, the release liner a was peeled off, and the test piece was attached to the surface of the glass plate via the pressure-sensitive adhesive sheet exposed by the peeling. Subsequently, heating was performed in an autoclave at 50 ℃ for 15 minutes, whereby the bonding of the test piece to the glass plate was stabilized, and a sample for evaluation was obtained. The thermal shock test was repeated at-40 ℃ and 85 ℃ for the obtained samples, and the presence or absence of cracking of the retardation film after 100, 200 and 300 thermal cycles was confirmed by an optical microscope. 3 samples were prepared for each optical laminate, and the ease of crack generation of the retardation film was evaluated based on the number of samples in which cracks were generated. The conditions of the thermal cycle are as follows.

1 Cycle after 30 minutes in an atmosphere at-40 ℃,30 minutes in an atmosphere at 85 ℃.

The evaluation results are shown in table 3 below. The "corona treatment" in table 3 refers to corona treatment for the adhesive sheet. The amounts of the residual monomers shown in table 3 are the total amounts of the residual monomers in all the adhesive sheets contained in the optical laminate to be evaluated. In the column of "easiness of cracking", the number of samples in which cracking occurred out of the 3 samples evaluated was denoted as n, and it was noted as "n/3".

TABLE 3

Industrial applicability

The optical laminate of the present invention can be used for an image display device, for example.

Claims

1. An optical laminate comprising:

An adhesive sheet formed from a photocurable composition containing a monomer group and/or a partial polymer of the monomer group, and

Retardation film,

The adhesive sheet is in contact with the phase difference film directly or via a layer having a thickness of 10 μm or less.

The amount of residual monomers contained in the pressure-sensitive adhesive sheet is 16000 ppm (weight basis) or less.

2. The optical laminate according to claim 1, wherein:

The optical laminate includes the two pressure-sensitive adhesive sheets disposed so as to sandwich the retardation film.

3. The optical layered body according to claim 1, wherein:

The optical laminate comprises two or more adhesive sheets.

The total amount of the residual monomers contained in the two or more PSA sheets is 16000 ppm (weight basis) or less.

4. The optical layered body according to claim 1, wherein:

The optical laminate further includes a polarizing film.

5. The optical layered body according to claim 4, wherein:

The polarizing film and the phase difference film sandwich the adhesive sheet.

6. The optical layered body according to claim 1, wherein:

The monomer group includes a (meth)acrylic monomer.

7. The optical layered body according to claim 1, wherein:

The monomer group includes a carboxyl group-containing monomer.

8. The optical layered body according to claim 7, wherein:

The content of the carboxyl group-containing monomer in the monomer group is 4.5% by weight or more.

9. The optical layered body according to claim 1, wherein:

The monomer group includes nitrogen atom-containing monomers.

10. The optical layered body according to claim 1, wherein:

The photocurable composition comprises a photopolymerization initiator,

The photopolymerization initiator is a compound having a chemical structure represented by the following formula (1) in the molecule,

^R1 and ^R2 in the formula (1) are each independently C1-C8 alkyl; C1-C4 alkyl whose hydrogen atom is substituted by -OH, C1-C4 alkoxy, -CN, ^-COOR51 , ^-OOCR52 or ^-NR53R54 ; C3-C6 ^alkenyl ; or _-CH2 - _C6H4 - _R55 ^,

^R1 and ^R2 may be bonded to each other to form a C2-C9 alkylene group, a C3-C6 oxyalkylene group, or an azaalkylene group,

X is -OR ⁵⁶ , or -NR ⁵⁷ R ⁵⁸ ,

R ⁵¹ is a C1-C8 alkyl group,

R ⁵² is a C1-C4 alkyl group,

R ⁵³ and R ⁵⁴ are each independently a hydrogen atom, a C1-C12 alkyl group; a C2-C4 alkyl group in which the hydrogen atom is substituted with at least one group selected from -OH, a C1-C4 alkoxy group, -CN and -COOR ⁵⁹ ; a C3-C5 alkenyl group; or a cyclohexyl group,

R ⁵³ and R ⁵⁴ are optionally C3-C9 alkylene groups which are bonded to each other and optionally interrupted by -O- or -N(R ⁶⁰ )-,

R ⁵⁵ is a C1-C4 alkyl group,

R ⁵⁶ is a hydrogen atom, -SiR ⁶² ₃ , a C1-C8 alkyl group, or a C3-C6 alkenyl group,

R ⁵⁷ and R ⁵⁸ are C1-C12 alkyl; C2-C4 alkyl in which the hydrogen atom is substituted by at least one group selected from -OH, C1-C4 alkoxy, -CN and -COOR ⁶³ ; C3-C5 alkenyl; or cyclohexyl,

R ⁵⁷ and R ⁵⁸ are optionally C3-C9 alkylene groups which are bonded to each other and optionally interrupted by -O- or -N(R ⁶⁴ )-,

R ⁵⁹ is a C1-C4 alkyl group,

R ⁶⁰ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a C1-C4 hydroxyalkyl group, -CH ₂ CH ₂ -COOR ⁶¹ or -CH ₂ CH ₂ CN,

R ⁶¹ is a C1-C4 alkyl group,

R ⁶² is a C1-C6 alkyl group,

R ⁶³ is a C1-C4 alkyl group,

R ⁶⁴ is a hydrogen atom, a C1-C4 alkyl group, an allyl group, a C1-C4 hydroxyalkyl group, -CH ₂ CH ₂ -COOR ⁶⁵ or -CH ₂ CH ₂ CN,

R ⁶⁵ is a C1-C4 alkyl group,

The chemical structure can be bonded to a hydrogen atom or a substituted structure of a hydrogen atom via the carbon atom represented by * in the formula (1).

11. The optical layered body according to claim 1, wherein:

The photocurable composition includes a first photopolymerization initiator having a relatively small first reaction rate and a second photopolymerization initiator having a relatively large second reaction rate.

The ratio of the second reaction rate to the first reaction rate, represented by the ratio of the polymerization rates A evaluated by the following measurement method using only the respective photopolymerization initiators, is 1.1 or more.

Determination method:

A mixed solution of 99 parts by weight of n-butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate as monomers and 0.1 parts by weight of a photopolymerization initiator to be evaluated is irradiated with ultraviolet rays to prepare a monomer slurry in which the monomers are partially polymerized; the ultraviolet irradiation is carried out until the viscosity of the mixed solution at 30° C. reaches 20 Pa·s; then, a coating layer with a thickness of 20 μm formed by the prepared monomer slurry is formed between a pair of polyethylene terephthalate (PET) sheets each having a thickness of 75 μm; then, the coating layer is irradiated with ultraviolet rays using an LED having a peak wavelength of 340 nm±10 nm as a light source from one side of the PET sheet; the illuminance and irradiation time of the irradiated ultraviolet rays are set to 4 mW/ ^cm2 and 1200 seconds, respectively; the polymerization rate of the monomer measured for the coating layer after photocuring by irradiation with the ultraviolet rays is determined as the polymerization rate A.

12. The optical layered body according to claim 1, wherein:

The adhesive sheet has a surface to which a surface modification treatment has been applied.

13. The optical layered body according to claim 1, wherein:

The thickness of the adhesive sheet is 50 μm or less.

14. The optical layered body according to claim 1, wherein:

The adhesive sheet has an anchoring force of 13 N/25 mm or more with respect to the phase difference film.

15 . An image display device comprising the optical layered body according to claim 1 .