KR20210049969A - Optical laminate - Google Patents

Abstract

To provide an optical laminate that can achieve both the adhesion and hardness of the hard coat layer and the base layer, and can be produced without requiring heating at a temperature that may cause deformation of the base film. The optical laminate of the present invention includes a base layer formed from a (meth)acrylic resin film, a hard coat layer formed by coating a composition for forming a hard coat layer on the (meth)acrylic resin film, and the base layer and the hard coat layer. Between the coat layers, the hard coat layer-forming composition permeates the (meth)acrylic resin film, and a permeable layer formed therein is provided. The composition for forming a hard coat layer contains a curable compound (A) containing at least one radically polymerizable unsaturated group and an aromatic ring, and a curable compound containing at least two radically polymerizable unsaturated groups, but does not contain an aromatic ring ( B) and a monofunctional monomer (C) which contains one radically polymerizable unsaturated group but does not contain an aromatic ring.

Description

Optical laminated body {OPTICAL LAMINATE}

The present invention relates to an optical laminate.

Image display devices such as a liquid crystal display (LCD), a cathode ray tube display device (CRT), a plasma display (PDP), and an electroluminescent display (ELD) display when scratches occur on their surface due to external contact. The visibility of the image may decrease. For this reason, for the purpose of protecting the surface of an image display device, an optical laminate comprising a base film and a hard coat layer is used. As the base film of the optical laminate, triacetyl cellulose (TAC) is typically used (Patent Document 1). However, the base film made of TAC has high moisture permeability. Therefore, when the optical laminated body containing such a base film is used for an LCD, a problem arises that moisture transmits through the optical laminate and deteriorates the optical properties of the polarizer under high temperature and high humidity. In recent years, in addition to indoor use, LCD is also used in outdoor equipment such as car navigation systems and portable information terminals in many cases, and the reliability of the above problem does not occur even under severe conditions such as high temperature and high humidity. High LCD is required.

In order to solve the above problem, the composition for forming a hard coat layer is impregnated into the base film by applying and heating the composition for forming a hard coat layer on an acrylic base film having low moisture permeability, whereby the base film and the hard coat layer Optical laminates having improved the adhesion of are proposed (for example, Patent Literature 2 and Patent Literature 3). However, in the manufacture of the optical laminated body of Patent Document 2, since it is necessary to heat at a temperature close to the Tg of the base film in order to obtain sufficient adhesion, there is a concern that the base film may be deformed (for example, shrink). On the other hand, in the manufacture of the optical laminate of Patent Document 3, the composition for forming a hard coat layer can be penetrated into the base film by heating at a relatively low temperature to improve adhesion, but the hardness may be insufficient.

Japanese Patent Application Laid-Open No. 2008-165205 Japanese Laid-Open Patent Publication No. 2012-234163 Japanese Unexamined Patent Publication No. 2013-50641

The present invention provides an optical laminate that can achieve both the adhesion and hardness of the hard coat layer and the base layer, and can be manufactured without requiring heating at a temperature that may cause deformation of the base film.

The optical laminate of the present invention includes a base layer formed from a (meth)acrylic resin film, a hard coat layer formed by coating a composition for forming a hard coat layer on the (meth)acrylic resin film, and the base layer and the hard coat layer. Between the coat layers, the hard coat layer-forming composition permeates the (meth)acrylic resin film, and a permeable layer formed therein is provided. The composition for forming a hard coat layer contains a curable compound (A) containing at least one radically polymerizable unsaturated group and an aromatic ring, and a curable compound containing at least two radically polymerizable unsaturated groups, but does not contain an aromatic ring ( B) and a monofunctional monomer (C) which contains one radically polymerizable unsaturated group but does not contain an aromatic ring.

In one embodiment, the content ratio of the curable compound (A) to all curable compounds in the composition for forming a hard coat layer is 10% by weight to 60% by weight.

In one embodiment, the total content ratio of the curable compound (A) and the monofunctional monomer (C) to all curable compounds in the composition for forming a hard coat layer is 20% by weight to 70% by weight.

In one embodiment, the composition for forming a hard coat layer contains, as a curable compound (B), a curable compound (B1) containing 9 or more radically polymerizable unsaturated groups.

In one embodiment, the weight average molecular weight of the monofunctional monomer (C) is 500 or less.

In one embodiment, the monofunctional monomer (C) has a hydroxyl group.

In one embodiment, the (meth)acrylic resin forming the (meth)acrylic resin film has a structural unit expressing positive birefringence and a structural unit expressing negative birefringence.

In one embodiment, the weight average molecular weight of the (meth)acrylic resin forming the (meth)acrylic resin film is 10000 to 500000.

In one embodiment, the surface of the hard coat layer on the opposite side to the permeable layer has an uneven structure.

In one embodiment, an antireflection layer is further provided on the side opposite to the penetration layer of the hard coat layer.

According to another aspect of the present invention, a polarizing film is provided. The polarizing film contains the said optical laminated body.

According to another aspect of the present invention, an image display device is provided. The image display device includes the optical laminate.

According to another aspect of the present invention, a method of manufacturing an optical laminate is provided. The manufacturing method includes applying a composition for forming a hard coat layer on a (meth)acrylic resin film to form a coating layer, and heating the coating layer at 50°C or more and less than 100°C. The composition for forming a hard coat layer contains a curable compound (A) containing at least one radically polymerizable unsaturated group and an aromatic ring, and a curable compound containing at least two radically polymerizable unsaturated groups, but does not contain an aromatic ring ( B) and a monofunctional monomer (C) which contains one radically polymerizable unsaturated group but does not contain an aromatic ring.

According to the present invention, by using a composition for forming a hard coat layer containing three types of curable compounds, both the adhesion and hardness of the base layer and the hard coat layer are excellent, and furthermore, deformation of the base film can be caused. An optical laminate is obtained that can be manufactured without requiring heating at a possible temperature.

Fig. 1(a) is a schematic cross-sectional view of an optical laminate according to a preferred embodiment of the present invention, and (b) is an example of a schematic cross-sectional view of an optical laminate having no permeable layer.
2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Overall configuration of optical laminate

Fig. 1(a) is a schematic sectional view of an optical laminate according to a preferred embodiment of the present invention, and Fig. 1(b) is a schematic sectional view of an optical laminate having no permeable layer. The optical laminated body 100 shown in FIG. 1(a) includes a base layer 10 formed from a (meth)acrylic resin film, a penetration layer 20, and a hard coat layer 30 in this order. . The hard coat layer 30 is formed by coating a composition for forming a hard coat layer on a (meth)acrylic resin film. The permeable layer 20 is formed by permeating the composition for forming a hard coat layer into a (meth)acrylic resin film. The base layer 10 is a portion in which the composition for forming a hard coat layer does not reach (permeate) in the (meth)acrylic resin film when the composition for forming a hard coat layer in this way penetrates the (meth)acrylic resin film. . On the other hand, in the optical laminated body 200 shown in Fig. 1(b), no penetration layer is formed. The boundary (A) shown in Figs. 1(a) and (b) is a boundary defined by the coating surface of the composition for forming a hard coat layer of a (meth)acrylic resin film. Therefore, the boundary (A) is a boundary between the permeable layer 20 and the hard coat layer 30 in the optical laminate 100, and in the optical laminate 200 in which no permeable layer is formed, the base layer ( 10') (that is, the (meth)acrylic resin film) and the hard coat layer 30'. In addition, in this specification, "(meth)acryl" means acrylic and/or methacrylic.

As described above, the permeable layer 20 is formed by permeating the composition for forming a hard coat layer into the (meth)acrylic resin film in the optical laminate 100. That is, in the (meth)acrylic resin film, the permeable layer 20 is a portion in which the hard coat layer component is present. The thickness of the permeable layer 20 is, for example, 1.0 µm or more. In addition, the thickness of the permeable layer 20 is the thickness of the portion in which the hard coat layer component is present in the (meth)acrylic resin film, and specifically, the hard coat layer component in the (meth)acrylic resin film is It is the distance between the boundary (B) between the existing part (permeable layer) and the non-existing part (substrate layer) and the boundary (A).

In the optical laminate of the present invention, if necessary, any suitable other layer (not shown) may be disposed outside the hard coat layer 30. Other layers are typically arranged via an adhesive layer (not shown).

The (meth)acrylic resin forming the (meth)acrylic resin film may be eluted into the composition for forming a hard coat layer, and the (meth)acrylic resin may be present in the hard coat layer.

2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention. The optical laminated body 300 further includes a block layer 40 on the side opposite to the permeable layer 20 of the hard coat layer 30. In the block layer 40, the (meth)acrylic resin forming the (meth)acrylic resin film is eluted into the composition for forming a hard coat layer, and the composition for forming the hard coat layer is phase separated from the (meth)acrylic resin. It is caused by causing The optical laminated body provided with the block layer 40 is excellent in hardness.

The amplitude of the reflection spectrum of the hard coat layer in the wavelength region of 500 nm to 600 nm of the optical laminate of the present invention is preferably 0.5% or less, more preferably 0.3% or less, and still more preferably 0.1 % Or less. According to the present invention, it is possible to obtain an optical laminate having a small amplitude of a reflection spectrum, that is, a small interference unevenness.

The pencil hardness on the surface of the hard coat layer of the optical laminate of the present invention is preferably 2H or more, and more preferably 3H or more.

The optical layered product of the present invention is applied to, for example, a polarizing film (also referred to as a polarizing plate). Specifically, in a polarizing film, the optical laminated body of the present invention is formed on one side or both sides of a polarizer, and can be preferably used as a protective material for a polarizer.

B. Substrate layer

The base layer is formed from a (meth)acrylic resin film. More specifically, as described above, when the composition for forming a hard coat layer is applied to the (meth)acrylic resin film, the composition for forming the hard coat layer reaches the (meth)acrylic resin film ( This is the part that did not penetrate.

The (meth)acrylic resin film contains a (meth)acrylic resin. The (meth)acrylic resin film is obtained by extrusion molding a molding material containing a resin component containing, for example, a (meth)acrylic resin as a main component.

The moisture permeability of the (meth)acrylic resin film is preferably 200 g/m 2 ·24 hr or less, and more preferably 80 g/m 2 ·24 hr or less. According to the present invention, even if a (meth)acrylic resin film having high moisture permeability is used as described above, an optical laminate having excellent adhesion between the (meth)acrylic resin film and the hard coat layer and suppressed interference non-uniformity can be obtained. . In addition, moisture permeability can be measured under the test conditions of 40 degreeC and 92% of relative humidity by the method according to JIS Z 0208, for example.

The transmittance of light at a wavelength of 380 nm of the (meth)acrylic resin film is preferably 15% or less, more preferably 12% or less, and still more preferably 9% or less. When the transmittance of light having a wavelength of 380 nm is in such a range, since excellent ultraviolet absorption ability is expressed, ultraviolet deterioration due to external light or the like of the optical laminate can be prevented.

The in-plane retardation Re of the (meth)acrylic resin film is preferably 10 nm or less, more preferably 7 nm or less, still more preferably 5 nm or less, particularly preferably 3 nm or less, most preferably It is preferably 1 nm or less. The retardation Rth in the thickness direction of the (meth)acrylic resin film is preferably 15 nm or less, more preferably 10 nm or less, still more preferably 5 nm or less, particularly preferably 3 nm or less, most preferably It is preferably 1 nm or less. If the in-plane retardation and the thickness direction retardation are in such a range, the adverse influence on the display characteristics of the image display device resulting from the retardation can be remarkably suppressed. More specifically, uneven interference or deformation of a 3D image when used in a liquid crystal display device for a 3D display can be significantly suppressed. A (meth)acrylic resin film having such a range of in-plane retardation and thickness direction retardation can be obtained using, for example, a (meth)acrylic resin having a glutarimide structure described later. In addition, the in-plane retardation Re and the thickness direction retardation Rth are each obtained by the following equation:

Re = (nx-ny) × d

Rth = (nx-nz) × d

Here, nx is the refractive index in the slow axis direction of the (meth)acrylic resin film, ny is the refractive index in the fast axis direction of the (meth)acrylic resin film, nz is the refractive index in the thickness direction of the (meth)acrylic resin film, d (Nm) is the thickness of the (meth)acrylic resin film. The slow axis refers to a direction in which the refractive index in the plane of the film becomes the maximum, and the fast axis refers to a direction perpendicular to the slow axis in the plane. Typically, Re and Rth are measured using light having a wavelength of 590 nm.

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be used. For example, poly(meth)acrylic acid ester such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (e.g., methyl methacrylate-cyclohexyl methacrylate copolymer, methacrylic acid Methyl-(meth)acrylate norbornyl copolymer, etc.) are mentioned. _{Preferably, poly(meth)acrylate C 1-6} alkyl such as poly(meth)acrylate methyl is used. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is mentioned.

The weight average molecular weight of the (meth)acrylic resin is preferably 10000 to 500000, more preferably 30000 to 300000, still more preferably 50000 to 200000. When the weight average molecular weight is within the range, compatibility with the composition for forming a hard coat layer is excellent. In addition, when the weight average molecular weight is too small, there is a tendency that the mechanical strength in the case of a film is insufficient. When the weight average molecular weight is too large, the viscosity at the time of melt extrusion is high, the molding processability decreases, and the productivity of the molded article tends to decrease.

The glass transition temperature of the (meth)acrylic resin is preferably 110°C or higher, and more preferably 120°C or higher. When the glass transition temperature is in such a range, a (meth)acrylic resin film excellent in durability and heat resistance can be obtained. The upper limit of the glass transition temperature is not particularly limited, but from the viewpoint of moldability and the like, it is preferably 170°C or less.

The (meth)acrylic resin preferably has a structural unit expressing positive birefringence and a structural unit expressing negative birefringence. If it has these structural units, the abundance ratio can be adjusted, the retardation of a (meth)acrylic resin film can be controlled, and a (meth)acrylic resin film of low phase difference can be obtained. As a structural unit expressing positive birefringence, for example, a lactone ring, polycarbonate, polyvinyl alcohol, cellulose acetate, polyester, polyallylate, polyimide, a structural unit constituting a polyolefin, etc., a general formula ( The structural unit represented by 1) is mentioned. As a structural unit expressing negative birefringence, for example, a structural unit derived from a styrene-based monomer, a maleimide-based monomer, or the like, a structural unit of polymethyl methacrylate, and a structural unit represented by general formula (3) described later And the like. In the present specification, the structural unit expressing positive birefringence means a structural unit when a resin having only the structural unit exhibits positive birefringence properties (that is, when a slow axis is expressed in the stretching direction of the resin). In addition, the structural unit expressing negative birefringence means a structural unit when a resin having only the structural unit exhibits negative birefringence properties (that is, when a slow axis is expressed in a direction perpendicular to the stretching direction of the resin).

As the (meth)acrylic resin, a (meth)acrylic resin having a lactone ring structure or a glutarimide structure is preferably used. The (meth)acrylic resin having a lactone ring structure or a glutarimide structure is excellent in heat resistance. More preferably, it is a (meth)acrylic resin which has a glutarimide structure. When a (meth)acrylic resin having a glutarimide structure is used, as described above, a (meth)acrylic resin film having a low moisture permeability and a low retardation and ultraviolet transmittance can be obtained. The (meth)acrylic resin having a glutarimide structure (hereinafter, also referred to as glutarimide resin) is, for example, JP 2006-309033, JP 2006-317560, JP 2006 -328329, JP 2006-328334, JP 2006-337491, JP 2006-337492, JP 2006-337493, JP 2006-337569, Japan It is described in Unexamined Patent Publication No. 2007-009182 and Japanese Unexamined Patent Publication No. 2009-161744. These descriptions are incorporated herein by reference.

Preferably, the glutarimide resin is a structural unit represented by the following general formula (1) (hereinafter, also referred to as a glutarimide unit) and a structural unit represented by the following general formula (2) (hereinafter, (meth)acrylic acid Also referred to as an ester unit).

[Formula 1]

In formula (1), R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is hydrogen, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or It is a substituent containing an aromatic ring having 5 to 15 carbon atoms. In formula (2), R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is hydrogen, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or It is a substituent containing an aromatic ring having 5 to 15 carbon atoms.

If necessary, the glutarimide resin may further contain a structural unit represented by the following general formula (3) (hereinafter, also referred to as an aromatic vinyl unit).

[Formula 2]

In formula (3), R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.

In the general formula (1), preferably, R ¹ and R ² are each independently hydrogen or a methyl group, R ³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group, more preferably, R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group.

The glutarimide resin may contain only a single type as a glutarimide unit, and may contain a plurality of types different ^{from R 1} , R ² , and R ^{3 in the general formula (1).} .

The glutarimide unit can be formed by imidizing the (meth)acrylic acid ester unit represented by the general formula (2). Further, the glutarimide unit is an acid anhydride such as maleic anhydride, or a half ester of such an acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms; Also formed by imidizing α,β-ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, and citraconic acid. I can.

In the general formula (2), preferably, R ⁴ and R ⁵ are each independently hydrogen or a methyl group, R ⁶ is hydrogen or a methyl group, more preferably R ⁴ is hydrogen, and R ⁵ Is a methyl group, and R ⁶ is a methyl group.

The glutarimide resin may contain only a single type as a (meth)acrylic acid ester unit, and includes a plurality of different types ^{of R 4} , R ⁵ , and R ^{6 in the general formula (2),} You may have it.

The glutarimide resin is an aromatic vinyl unit represented by the general formula (3), preferably styrene, α-methylstyrene, and the like, and more preferably styrene. By having such an aromatic vinyl unit, the positive birefringence of the glutarimide structure can be reduced, and a (meth)acrylic resin film having a lower phase difference can be obtained.

The glutarimide resin may contain only a single type as an aromatic vinyl unit, and may contain a plurality of types different from ^{R 7} and R ^8.

It is preferable to change the content of the glutarimide unit in the glutarimide resin ^{depending on, for example, the structure of R 3.} The content of the glutarimide unit is preferably 1% by weight to 80% by weight, more preferably 1% by weight to 70% by weight, further preferably They are 1% by weight to 60% by weight, particularly preferably 1% by weight to 50% by weight. When the content of the glutarimide unit is in such a range, a low-phase difference (meth)acrylic resin film excellent in heat resistance can be obtained.

The content of the aromatic vinyl unit in the glutarimide resin may be appropriately set according to the purpose or desired properties. Depending on the application, the content of the aromatic vinyl unit may be zero. When the aromatic vinyl unit is contained, the content thereof is preferably 10% by weight to 80% by weight, more preferably 20% by weight to 80% by weight, based on the glutarimide unit of the glutarimide resin. , More preferably 20% by weight to 60% by weight, particularly preferably 20% by weight to 50% by weight. When the content of the aromatic vinyl unit is within such a range, a (meth)acrylic resin film excellent in low phase difference, heat resistance, and mechanical strength can be obtained.

In the glutarimide resin, if necessary, a glutarimide unit, a (meth)acrylic acid ester unit, and other structural units other than the aromatic vinyl unit may be further copolymerized. Examples of other structural units include nitrile monomers such as acrylonitrile and methacrylonitrile, maleimides such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. Structural units composed of system monomers can be mentioned. These other structural units may be directly copolymerized or graft copolymerized in the glutarimide resin.

The (meth)acrylic resin film contains an ultraviolet absorber. As the ultraviolet absorber, any suitable ultraviolet absorber may be employed as long as the desired properties are obtained. Representative examples of the ultraviolet absorber include a triazine ultraviolet absorber, a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, a cyanoacrylate ultraviolet absorber, a benzoxazine ultraviolet absorber, and an oxadiazole ultraviolet absorber. . These ultraviolet absorbers may be used alone, or may be used in combination of a plurality of them.

The content of the ultraviolet absorber is preferably 0.1 parts by weight to 5 parts by weight, and more preferably 0.2 parts by weight to 3 parts by weight, based on 100 parts by weight of the (meth)acrylic resin. When the content of the ultraviolet absorber is in such a range, ultraviolet rays can be effectively absorbed, and the transparency of the film at the time of film forming does not decrease. When the content of the ultraviolet absorber is less than 0.1 part by weight, the blocking effect of ultraviolet rays tends to be insufficient. When the content of the ultraviolet absorber is more than 5 parts by weight, the coloration becomes intense, the haze of the film after molding becomes high, and the transparency tends to deteriorate.

The (meth)acrylic resin film may contain any appropriate additive depending on the purpose. Examples of additives include antioxidants such as hindered phenol, phosphorus, and sulfur; Stabilizers such as light-resistant stabilizers, weather-resistant stabilizers, and heat stabilizers; Reinforcing materials such as glass fiber and carbon fiber; Near-infrared absorber; Flame retardants such as tris(dibromopropyl)phosphate, triallyl phosphate, and antimony oxide; Antistatic agents such as anionic, cationic, and nonionic surfactants; Coloring agents such as inorganic pigments, organic pigments, and dyes; Organic fillers and inorganic fillers; Resin modifier; Plasticizer; Lubricant; And a retardation reducing agent. The type, combination, content, etc. of the additives to be contained may be appropriately set according to the purpose or desired properties.

Although it does not specifically limit as a manufacturing method of the said (meth)acrylic resin film, For example, (meth)acrylic resin, an ultraviolet absorber, and, if necessary, other polymers or additives, any suitable mixing method After sufficiently mixing with, and making it a thermoplastic resin composition in advance, this can be film-molded. Alternatively, a (meth)acrylic resin, an ultraviolet absorber, and if necessary, other polymers or additives, etc. may be mixed into different solutions and then mixed to obtain a uniform liquid mixture, and then film-molded.

In preparing the thermoplastic resin composition, for example, after pre-blending the film raw materials with an arbitrary suitable mixer such as an omni mixer, the obtained mixture is extruded and kneaded. In this case, the mixer used for extrusion and kneading is not particularly limited, and for example, any suitable mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used.

As the method of forming the film, any suitable film forming method such as a solution casting method (solution casting method), a melt extrusion method, a calender method, and a compression molding method may be mentioned. The melt extrusion method is preferred. Since the melt extrusion method does not use a solvent, it is possible to reduce the manufacturing cost and the load on the global environment or work environment caused by the solvent.

Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is preferably 150 to 350°C, more preferably 200 to 300°C.

In the case of forming a film by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded into a film is wound up to obtain a roll-shaped film. At this time, it is also possible to uniaxially stretch by appropriately adjusting the temperature of the take-up roll and stretching in the extrusion direction. Further, simultaneous biaxial stretching and sequential biaxial stretching may be performed by stretching the film in a direction perpendicular to the extrusion direction.

The (meth)acrylic resin film may be either an unstretched film or a stretched film as long as the desired retardation is obtained. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used.

The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition as a raw material for the film, specifically, preferably (glass transition temperature-30°C) to (glass transition temperature + 30°C), more preferably Is in the range of (glass transition temperature-20°C) to (glass transition temperature + 20°C). If the stretching temperature is less than (glass transition temperature-30°C), there is a fear that the haze of the obtained film increases, or the film is torn or cracks occur, and a predetermined draw ratio may not be obtained. Conversely, when the stretching temperature exceeds (glass transition temperature + 30° C.), there is a tendency that the resulting film has a large thickness unevenness, or mechanical properties such as elongation, tear propagation strength, and oil fatigue resistance cannot be sufficiently improved. In addition, there is a tendency that troubles such as adhesion of the film to the roll are likely to occur.

The draw ratio is preferably 1.1 to 3 times, more preferably 1.3 to 2.5 times. When the draw ratio is within such a range, mechanical properties such as elongation, tear propagation strength, and oil fatigue resistance of the film can be significantly improved. As a result, it is possible to produce a film having small thickness non-uniformity, substantially zero birefringence (hence, small phase difference), and small haze.

The (meth)acrylic resin film may be subjected to heat treatment (annealing) or the like after stretching treatment in order to stabilize its optical isotropy and mechanical properties. As the conditions for heat treatment, any suitable conditions can be adopted.

The thickness of the (meth)acrylic resin film is preferably 10 µm to 200 µm, more preferably 20 µm to 100 µm. If the thickness is less than 10 µm, there is a fear that the strength will decrease. When the thickness exceeds 200 µm, there is a concern that transparency may decrease.

The wetting tension on the surface of the (meth)acrylic resin film is preferably 40 mN/m or more, more preferably 50 mN/m or more, and still more preferably 55 mN/m or more. When the surface wetting tension is at least 40 mN/m or more, the adhesion between the (meth)acrylic resin film and the hard coat layer is further improved. In order to adjust the wetting tension of the surface, any suitable surface treatment can be performed. Examples of the surface treatment include corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, and chemical treatment. Among these, preferably, they are corona discharge treatment and plasma treatment.

C. Penetration layer

As described above, the permeable layer is formed by infiltrating the composition for forming a hard coat layer into the (meth)acrylic resin film. In other words, the permeable layer may correspond to a part of the commercialization area of the (meth)acrylic resin forming the (meth)acrylic resin film and the component forming the hard coat layer.

In the permeable layer, it is preferable that the concentration of the (meth)acrylic resin forming the (meth)acrylic resin film is continuously increased from the side of the hard coat layer to the side of the substrate layer. Interfacial reflection can be suppressed by continuously changing the concentration of the (meth)acrylic resin, i.e., the interface resulting from the change in the concentration of the (meth)acrylic resin, and an optical laminate with less interference unevenness can be obtained. Because you can get it.

The lower limit of the thickness of the permeable layer is, for example, 1.0 µm, preferably 1.2 µm, more preferably 1.5 µm, and still more preferably 2 µm. The upper limit of the thickness of the permeable layer is preferably (thickness of (meth)acrylic resin film × 70%) µm, more preferably (thickness of (meth)acrylic resin film × 40%) µm, further preferably Is (thickness of a (meth)acrylic resin film x 30%) µm, and particularly preferably ((meth)acrylic resin film x 20%) µm. When the thickness of the permeable layer is within such a range, an optical layered product having excellent adhesion between the (meth)acrylic resin film and the hard coat layer and suppressing interference unevenness can be obtained. In addition, the thickness of the permeable layer can be measured by the reflection spectrum of the hard coat layer or observation with an electron microscope such as SEM or TEM. The details of the method of measuring the thickness of the permeable layer by the reflection spectrum will be described later as an evaluation method in Examples.

D. Hard coat layer

The hard coat layer is formed by coating the composition for forming a hard coat layer on the (meth)acrylic resin film as described above. The composition for forming a hard coat layer contains a curable compound that can be cured by, for example, heat, light (ultraviolet rays, etc.), electron beams, or the like. Preferably, the composition for forming a hard coat layer contains a photocurable curable compound. The curable compound may be any of a monomer, an oligomer, and a prepolymer.

The composition for forming a hard coat layer contains, as essential constituents, a curable compound (A) containing at least one radically polymerizable unsaturated group and an aromatic ring, and two or more radically polymerizable unsaturated groups, but contains an aromatic ring. It contains the curable compound (B) which does not contain, and the monofunctional monomer (C) which contains one radically polymerizable unsaturated group, but does not contain an aromatic ring. Examples of the radically polymerizable unsaturated group include a (meth)acryloyl group and a (meth)acryloyloxy group. According to the composition for forming a hard coat layer containing the three types of curable compounds, even if the heating temperature of the coating layer (described later) at the time of forming the hard coat layer is set low, the (meth)acrylic resin film and the hard coat layer are An optical laminate having excellent adhesion and hardness can be obtained.

The curable compound (A) contains a radically polymerizable unsaturated group and one or more aromatic rings, respectively. The curable compound (A) can improve the cohesive strength of the compatible region of the (meth)acrylic resin and the forming component of the hard coat layer, and, as a result, can improve the adhesion between the base layer and the hard coat layer. In addition, since the curable compound (A) can make the hard coat layer high refractive index, when a low refractive index antireflection layer is laminated on the hard coat layer, an antireflection film having a lower reflectance can be obtained.

The number of radically polymerizable unsaturated groups contained in the curable compound (A) is preferably 1 to 4. Further, the number of aromatic rings contained in the curable compound (A) is preferably 1 to 6. As an aromatic ring, a benzene ring, a hetero ring, or their condensed ring can be illustrated. Preferably, the aromatic ring is a benzene ring. The aromatic ring may or may not have a substituent.

As specific examples of the curable compound (A), ethoxylated o-phenylphenol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, benzyl (meth)acrylate, 2-hydroxy-3-phenoxy ( Oligomers or prepolymers of (meth)acrylates containing monomers such as meth)acrylate and phenoxyethyl (meth)acrylate, aryl groups such as benzyl groups and phenyl groups, or fluorene structures. The curable compound (A) may be used alone, or may be used in combination of a plurality of them.

The molecular weight (a weight average molecular weight in the case of an oligomer or polymer) of the curable compound (A) is preferably 250 or more, more preferably exceeds 450, and still more preferably 450 to 10000. When the molecular weight is within this range, since the cohesive force in the compatible region can be sufficiently improved, an optical laminate having excellent adhesion between the substrate layer and the hard coat layer can be obtained.

The content ratio of the curable compound (A) to the total curable compound in the composition for forming a hard coat layer is 10% by weight to 60% by weight, preferably 15% by weight to 55% by weight, more preferably 20% by weight It is-50% by weight. In such a range, the heating temperature at the time of forming the hard coat layer can be set low, the heating time can be set short, and the optical laminate in which the deformation due to heating (e.g., shrinkage of the (meth)acrylic resin film) is suppressed is efficient. Can be produced.

While the curable compound (B) contains two or more radically polymerizable unsaturated groups, it does not contain an aromatic ring. When the composition for forming a hard coat layer contains a polyfunctional curable compound (B) containing two or more radically polymerizable unsaturated groups, a hard coat layer having sufficient hardness can be formed.

In one embodiment, the composition for forming a hard coat layer contains, as a curable compound (B), a curable compound (B1) containing 9 or more radically polymerizable unsaturated groups. When a hard coat layer is formed by coating a composition for forming a hard coat layer containing a curable compound (B1), a component in the (meth)acrylic resin film eluted in the composition for forming a hard coat layer (typically, (meth)acrylic The resin component in the resin film) is prevented from diffusing to the air interface of the hard coat layer at the time of formation of the hard coat layer, and an optical laminate having excellent hardness can be obtained. Preferably, a block layer made of the curable compound (B1) is formed on the hard coat layer. When the block layer is formed, an optical laminate having more excellent hardness can be obtained. The number of radically polymerizable unsaturated groups contained in the curable compound (B1) is preferably 10 or more, more preferably 15 or more, and still more preferably 20 to 100. As the number of radically polymerizable unsaturated groups contained in the curable compound (B1) increases, the hardness of the hard coat layer itself can be improved.

Examples of the curable compound (B1) include urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, melamine (meth)acrylate, triazine (meth)acrylate, and silicone ( Oligomers or prepolymers such as meth)acrylate; And a methacrylate polymer having an unsaturated group. Among them, from the viewpoint of reactivity and transparency, oligomers or prepolymers of urethane (meth)acrylate are preferred. The curable compound (B1) may be used alone, or may be used in combination of a plurality of them.

The urethane (meth)acrylate can be obtained, for example, by reacting (meth)acrylic acid or hydroxy (meth)acrylate obtained from a (meth)acrylic acid ester and a polyol with a diisocyanate.

As the (meth)acrylic acid ester, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Can be mentioned.

Examples of the polyol include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, hydroxypi Neopentyl glycol ester, tricyclodecanedimethylol, 1,4-cyclohexanediol, spiroglycol, hydrogenated bisphenol A, ethylene oxide added bisphenol A, propylene oxide added bisphenol A, trimethylolethane, trimethylolpropane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, glucose, etc. are mentioned.

As the diisocyanate, for example, various diisocyanates of aromatic, aliphatic or alicyclic can be used. As a specific example of the diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3 ,3-dimethyl-4,4-diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-diphenylmethane diisocyanate, and hydrogenated products thereof.

The weight average molecular weight of the curable compound (B1) is preferably 1000 or more, more preferably 1500 or more, and still more preferably 2000 to 50000. Since the curable compound (B1) has 9 or more radically polymerizable unsaturated groups, even if the curable compound (B1) has a relatively small weight average molecular weight, the component in the (meth)acrylic resin film does not diffuse to the air interface of the hard coat layer. It is prevented, and an optical laminated body excellent in hardness can be obtained. Of course, for the purpose of obtaining an optical laminate having more excellent hardness, and the like, a curable compound (B1) having a larger weight average molecular weight may be used.

In another embodiment, the composition for forming a hard coat layer may contain, as a curable compound (B), a curable compound (B2) having 2 to 8 radically polymerizable unsaturated groups. In this other embodiment, the composition for forming a hard coat layer may contain only the curable compound (B2) as the curable compound (B), but from the viewpoint of obtaining an optical laminate having superior hardness, the curable compound (B1 ) It is preferable to contain both of the curable compound (B2).

The number of radically polymerizable unsaturated groups contained in the curable compound (B2) may be 2 to 6, for example. When the composition for forming a hard coat layer contains a curable compound (B2) containing 2 to 6 radically polymerizable unsaturated groups, even if the heating temperature of the coating layer at the time of forming the hard coat layer is set low, (meth) An optical laminate having excellent adhesion between the acrylic resin film and the hard coat layer can be obtained.

Examples of the curable compound (B2) include polyethylene glycol di(meth)acrylate, tricyclodecanedimethanol diacrylate, 1,10-decanediol diacrylate, 1,6-hexanediol diacrylate, 1 ,9-nonanediol diacrylate, dipropylene glycol diacrylate, polypropylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dimethylolpropanetetra Acrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol(meth)acrylate , Isocyanuric acid tri(meth)acrylate, ethoxylated glycerin triacrylate, ethoxylated pentaerythritol tetraacrylate, and compounds having a (meth)acryloyl group such as oligomers or polymers thereof; Urethane (meth)acrylate, and oligomers or prepolymers thereof, and the like. These compounds may be used alone, or may be used in combination of a plurality of them.

Curable compound (B2) preferably has a hydroxyl group. When the composition for forming a hard coat layer contains such a curable compound (B2), the heating temperature at the time of forming the hard coat layer can be set lower, the heating time can be set shorter, and deformation due to heating is suppressed. Sieve can be produced efficiently. Further, an optical laminate having excellent adhesion between the (meth)acrylic resin film and the hard coat layer can be obtained. Examples of the curable compound (B2) having a hydroxyl group include pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and the like.

The weight average molecular weight of the curable compound (B2) is preferably 3000 or less, more preferably 2000 or less, still more preferably 1500 or less, particularly preferably 1000 or less, and particularly preferably 500 or less. By using the curable compound (B2) having a relatively small weight average molecular weight, the thickness of the permeable layer can be increased. As a result, it is possible to obtain an optical laminate having excellent adhesion between the (meth)acrylic resin film and the hard coat layer, and suppressing interference unevenness.

The content ratio of the curable compound (B) to the total curable compound in the composition for forming a hard coat layer is 30% by weight to 80% by weight, preferably 30% by weight to 75% by weight, more preferably 35% by weight. They are -70% by weight, particularly preferably 40% by weight to 60% by weight. In such a range, an optical laminate having sufficient hardness can be obtained.

When the composition for forming a hard coat layer contains both the curable compound (B1) and the curable compound (B2), the blending weight ratio (B1/B2) thereof is, for example, 30/70 to 99/1, preferably May be 40/60 to 99/1, more preferably 50/50 to 99/1.

While the monofunctional monomer (C) contains one radically polymerizable unsaturated group, it does not contain an aromatic ring. Since the monofunctional monomer (C) easily penetrates the (meth)acrylic resin film, a penetration layer can be preferably formed. In addition, if the composition for forming a hard coat layer contains a monofunctional monomer (C), the heating temperature at the time of forming the hard coat layer can be set to be low, the heating time can be set to be short, and an optical laminate in which deformation due to heating is suppressed can be obtained. It can be produced efficiently.

The weight average molecular weight of the monofunctional monomer (C) is preferably 500 or less, more preferably 300 or less, still more preferably less than 250, and particularly preferably less than 200. If it is such a monofunctional monomer, it easily permeates and diffuses into a (meth)acrylic resin film. Examples of such monofunctional monomers include methoxypolyethylene glycol (meth)acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isooctyl acrylate, isostearyl acrylate, cyclohexyl acrylate, Isophoronylacrylate, acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, dimethylaminopropylacrylamide, N-(2-hydroxyethyl) ( Meth)acrylamide, acryloylmorpholine, and the like.

The monofunctional monomer (C) preferably has a polar group such as a hydroxyl group, an ether, and an amine (including a morpholine ring), and more preferably has a hydroxyl group. If it is such a monofunctional monomer, it is excellent in permeability or solubility to a (meth)acrylic resin film. As a result, the heating temperature at the time of forming the hard coat layer can be set lower, the heating time can be set shorter, and an optical laminate in which deformation due to heating is suppressed can be efficiently produced. Further, when the composition for forming a hard coat layer contains a monofunctional monomer having a hydroxyl group, an optical laminate having excellent adhesion between the (meth)acrylic resin film and the hard coat layer can be obtained. Examples of such monofunctional monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 1,4-cyclo Hydroxyalkyl (meth)acrylates such as hexane methanol monoacrylate; N-(2-hydroxyalkyl)(meth)acrylamide, cyclohexanedimethanol monoacrylate, etc., such as N-(2-hydroxyethyl)(meth)acrylamide, N-methylol(meth)acrylamide, etc. Can be lifted. Among these, 4-hydroxybutyl acrylate and N-(2-hydroxyethyl) acrylamide are preferred.

It is preferable that the boiling point of the monofunctional monomer (C) is higher than the heating temperature (described later) of the coating layer at the time of forming the hard coat layer. The boiling point of the monofunctional monomer is, for example, preferably 150°C or higher, more preferably 180°C or higher, and particularly preferably 200°C or higher. In such a range, the monofunctional monomer can be prevented from volatilization due to heating at the time of forming the hard coat layer, and the monofunctional monomer can be sufficiently permeated into the (meth)acrylic resin film.

The content ratio of the monofunctional monomer (C) to the total curable compound in the composition for forming a hard coat layer is preferably 10% by weight to 40% by weight, more preferably 12% by weight to 35% by weight, still more preferably Is from 15% by weight to 30% by weight. If the content ratio of the monofunctional monomer (C) is within such a range, the heating temperature at the time of forming the hard coat layer can be set low, the heating time can be set short, and an optical laminate in which deformation due to heating is suppressed can be efficiently produced. have.

The total content ratio of the curable compound (A) and the monofunctional monomer (C) to all the curable compounds in the composition for forming a hard coat layer is preferably from 20% by weight to 70% by weight, more preferably from 30% by weight. 65% by weight, more preferably 40% by weight to 60% by weight.

The composition for forming a hard coat layer preferably contains any suitable photopolymerization initiator. As a photoinitiator, for example, 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dime Toxybenzophenone, benzoinpropyl ether, benzyldimethylketal, N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone, 1-(4-isopropylphenyl)-2-hydroxy -2-methylpropan-1-one, thioxanthone compounds, and the like.

In one embodiment, the surface of the hard coat layer on the opposite side to the base layer has an uneven structure. If the surface of the hard coat layer has an uneven structure, anti-glare properties can be imparted to the optical laminate. As a method of forming such an uneven structure, a method of including fine particles in the composition for forming a hard coat layer is exemplified. The fine particles may be inorganic fine particles or organic fine particles. Examples of the inorganic fine particles include silicon oxide fine particles, titanium oxide fine particles, aluminum oxide fine particles, zinc oxide fine particles, tin oxide fine particles, calcium carbonate fine particles, barium sulfate fine particles, talc fine particles, kaolin fine particles, calcium sulfate fine particles, etc. have. Examples of the organic fine particles include polymethyl methacrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, and polyolefin. Resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyethylene fluoride resin powder, and the like. These fine particles may be used individually or may be used in combination of a plurality.

The shape of the fine particles may be any suitable shape. It is preferably approximately spherical, more preferably approximately spherical with an aspect ratio of 1.5 or less. The weight average particle diameter of the fine particles is preferably 1 µm to 30 µm, more preferably 2 µm to 20 µm. The weight average particle diameter of the fine particles can be measured, for example, by a coulter count method.

When the composition for forming the hard coat layer contains the fine particles, the content ratio of the fine particles is preferably 1% by weight to 60% by weight with respect to the total amount of the monomer, oligomer, and prepolymer in the composition for forming the hard coat layer. , More preferably, they are 2 weight%-50 weight%.

The composition for forming a hard coat layer may further contain any suitable additive. Examples of the additives include leveling agents, anti-blocking agents, dispersion stabilizers, thixotropic agents, antioxidants, ultraviolet absorbers, antifoaming agents, thickeners, dispersants, surfactants, catalysts, fillers, lubricants, antistatic agents, and the like.

Examples of the leveling agent include a fluorine-based or silicone-based leveling agent, and preferably a silicone-based leveling agent. Examples of the silicone-based leveling agent include reactive silicone, polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane. Among them, reactive silicone is preferred. When reactive silicone is added, the slip property is imparted to the surface of the hard coat layer and the scratch resistance is maintained over a long period of time. The content ratio of the leveling agent is preferably 5% by weight or less, and more preferably 0.01% by weight to 5% by weight with respect to the total amount of the monomer, oligomer, and prepolymer in the composition for forming a hard coat layer.

The composition for forming a hard coat layer may or may not contain a solvent. As a solvent, for example, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane , Tetrahydrofuran, acetone, methyl ethyl ketone (MEK), diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone (CPN), cyclohexanone, methyl cyclohexanone, ethyl formate, propyl formate, formic acid n-pentyl, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, acetylacetone, diacetone alcohol, methyl acetoacetate, ethyl acetoacetate, methanol, ethanol, 1-propanol, 2-propanol, 1- Butanol, 2-butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, isopropyl alcohol (IPA), isobutyl acetate, methyl isobutyl ketone (MIBK), 2-octanone, 2-penta Non, 2-hexanone, 2-heptanone, 3-heptanone, ethylene glycol monoethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene And glycol monomethyl ether. These may be used individually or may be used in combination of a plurality.

According to the present invention, even if a composition for forming a hard coat layer containing no solvent or a composition for forming a hard coat layer containing only a poor solvent of a (meth)acrylic resin film forming material as a solvent is used, forming a hard coat The solvent composition penetrates into the (meth)acrylic resin film, and a penetration layer having a desired thickness can be formed.

The thickness of the hard coat layer is preferably 1 µm or more, more preferably 3 µm or more, and still more preferably 4 µm to 10 µm. If it is such a range, an optical laminated body excellent in hardness can be obtained. Further, in the optical laminate of the present invention, since diffusion of the components in the (meth)acrylic resin film into the hard coat layer (composition for forming a hard coat layer) is suppressed as described above, even if the thickness of the hard coat layer is reduced, It has excellent hardness.

As described above, the (meth)acrylic resin forming the (meth)acrylic resin film may be eluted into the composition for forming a hard coat layer, and the (meth)acrylic resin may be present in the hard coat layer. In the present invention, since the hard coat layer is formed by the composition for forming a hard coat layer containing a polyfunctional curable compound (B), the (meth)acrylic resin is prevented from moving to the surface side of the hard coat layer. can do. In one embodiment, the concentration of the (meth)acrylic resin is continuously lowered from the base layer side of the permeable layer to the hard coat layer. In such an embodiment, since the concentration of the (meth)acrylic resin continuously changes, that is, the interface caused by the change in the concentration of the (meth)acrylic resin is not formed, it is possible to suppress interfacial reflection, and interference. An optical laminate with little unevenness can be obtained. In another embodiment, the (meth)acrylic resin and the composition for forming a hard coat layer are phase-separated, and a block layer is formed on the side opposite to the permeable layer of the hard coat layer. Also in such an embodiment, it is preferable that the concentration of the (meth)acrylic resin is continuously lowered from the base layer side of the permeable layer to the hard coat layer excluding the block layer.

The thickness of the block layer is preferably 1 µm to 10 µm, more preferably 2 µm to 5 µm.

In addition, the thickness of the block layer can be measured by the reflection spectrum of the hard coat layer or observation with an electron microscope such as SEM or TEM.

E. Other layers

In the optical laminate of the present invention, if necessary, any suitable other layer may be disposed outside the hard coat layer. Representative examples include an antireflection layer and an anti-glare layer. As the anti-reflection layer and anti-glare layer, an anti-reflection layer and an anti-glare layer commonly used in the art may be employed.

F. Manufacturing method of optical laminated body

The manufacturing method of the optical laminate of the present invention includes applying a composition for forming a hard coat layer on a (meth)acrylic resin film to form a coating layer, and heating the coating layer. Preferably, the hard coat layer is formed by curing the coating layer after heating.

Any suitable method can be adopted as a method of applying the composition for forming a hard coat layer. For example, a bar coat method, a roll coat method, a gravure coat method, a rod coat method, a slot orifice coat method, a curtain coat method, a fountain coat method, and a comma coat method are mentioned.

The heating temperature of the coating layer may be set to an appropriate temperature depending on the composition of the composition for forming a hard coat layer, and is preferably set to be less than or equal to the glass transition temperature of the resin contained in the (meth)acrylic resin film. When heated at a temperature equal to or lower than the glass transition temperature of the resin contained in the (meth)acrylic resin film, it is possible to obtain an optical laminate in which deformation due to heating was suppressed. The heating temperature of the coating layer is, for example, 50°C or more and less than 100°C, preferably 50°C or more and less than 80°C, and more preferably 50°C to 75°C. When heated at a temperature in such a range, the monomer, oligomer, and/or prepolymer (particularly, monofunctional monomer (C)) in the composition for forming a hard coat layer is satisfactorily penetrated and diffused into the (meth)acrylic resin film. The permeable layer described in the above item C is formed by the composition for forming a hard coat layer and the material for forming a (meth)acrylic resin film that have penetrated through the heating and subsequent curing treatment. As a result, it is possible to obtain an optical laminate having excellent adhesion between the (meth)acrylic resin film and the hard coat layer, and suppressing interference unevenness. In addition, when the composition for forming a hard coat layer contains a solvent, the applied composition for forming a hard coat layer can be dried by the heating.

In one embodiment, the heating temperature can be set according to the content ratio of the curable compound (A) and the monofunctional monomer (C). For example, if the total content ratio of the curable compound (A) and the monofunctional monomer (C) to all curable compounds in the composition for forming a hard coat layer is 20% by weight to 70% by weight, at a heating temperature of less than 80°C , It is possible to obtain an optical laminate having excellent adhesion and hardness, and suppressed interference unevenness and deformation due to heating, and a manufacturing process having low environmental load and high efficiency can be obtained.

As the hardening treatment, any suitable hardening treatment can be employed. Typically, the curing treatment is performed by ultraviolet irradiation. The accumulated light amount of ultraviolet irradiation is preferably 200 mJ to 400 mJ.

Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. The evaluation method in Examples is as follows. In addition, in Examples, unless otherwise specified, "parts" and "%" are based on weight.

(1) pencil hardness

About the hard coat layer side surface of the optical laminated body obtained in Examples and Comparative Examples, according to JIS K 5400 (load 500 g), pencil hardness was measured, and evaluated according to the following criteria.

○: Pencil hardness is 2H or more.

X: Pencil hardness is H or less.

(2) adhesion of the hard coat layer

The adhesion of the hard coat layer to the base film was measured according to the cross cut peeling test (substrate scale number: 100) of JIS K-5400, and evaluated according to the following criteria.

○: The number of peelings is 0.

X: The number of peelings is 1 or more.

(3) interference non-uniformity

On the side of the base film of the optical laminate obtained in Examples and Comparative Examples, a black acrylic plate (manufactured by Mitsubishi Rayon, thickness 2 mm) was adhered through an acrylic pressure-sensitive adhesive, and then, under a 3-wavelength fluorescent lamp, interference non-uniformity was visually observed. And evaluated based on the following criteria.

○: No occurrence of interference unevenness.

X: The occurrence of interference unevenness is confirmed.

(4) thickness of the penetration layer

A black acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd., thickness 2 mm) was adhered to the substrate layer side of the optical laminate obtained in Examples and Comparative Examples through an acrylic pressure-sensitive adhesive having a thickness of 20 µm. Next, the reflection spectrum of the hard coat layer was measured under the following conditions using an instantaneous multi-photometric system (manufactured by Otsuka Electronics Co., Ltd., brand name: MCPD3700), and from the peak position of the FFT spectrum, (hard coat layer + penetration layer) The thickness was evaluated. Incidentally, the refractive index was measured by selecting monobromonaphthalene as an intermediate solution using an Abbe refractometer (trade name: DR-M2/1550) manufactured by Atago Corporation.

· Reflection spectrum measurement conditions

Reference: Mirror

Algorithm: FFT method

Calculation wavelength: 450 nm to 850 nm

· Detection conditions

Exposure time: 20 ms

Ramp Gain: Normal

Number of integrations: 10 times

· FFT method

Film thickness range: 2 to 15 ㎛

Film thickness resolution: 24 ㎚

In addition, the thickness of the hard coat layer was evaluated by the measurement of the reflection spectrum for the following laminate (R).

Laminate (R): The same as in Example 1, except that a PET substrate (manufactured by Toray, brand name: U48-3, refractive index: 1.60) was used as the substrate film, and the heating temperature of the coating layer was set to 60°C. I got it.

In addition, since the composition for hard coat layer formation does not penetrate into the PET substrate used in the laminate, the thickness of only the hard coat layer is measured from the peak position of the FFT spectrum obtained from the laminate (R). As a result of this evaluation, the thickness of the hard coat layer was 5.3 µm.

The positive value calculated from (thickness of (hard coat layer + permeable layer))-(thickness of (hard coat layer)) was taken as the thickness of the permeable layer.

<Production Example 1> Preparation of base film A

100 parts by weight of the imidized MS resin (weight average molecular weight: 105,000) described in Preparation Example 1 of JP 2010-284840 A and 0.62 parts by weight of a triazine-based ultraviolet absorber (manufactured by Adeka Corporation, brand name: T-712), biaxial kneading It mixed at 220 degreeC with a group, and the resin pellet was produced. The obtained resin pellets were dried at 100.5 kPa and 100°C for 12 hours, extruded from a T-die at a die temperature of 270°C with a single screw extruder to form a film (thickness: 160 μm). Moreover, the said film was stretched in the 150 degreeC atmosphere in the conveyance direction (thickness 80 micrometers), and then stretched in a 150 degreeC atmosphere in the direction orthogonal to the film conveyance direction, and the base film A ((meth) of 40 micrometers in thickness) Acrylic resin film) was obtained. The light transmittance of the obtained base film A at a wavelength of 380 nm was 8.5%, the in-plane retardation Re was 0.4 nm, and the thickness direction retardation Rth was 0.78 nm. Moreover, the moisture permeability of the obtained base film A was 61 g/m 2 ·24 hr. In addition, as for the light transmittance, the transmittance spectrum was measured in a wavelength range of 200 nm to 800 nm using a spectrophotometer (device name: U-4100) manufactured by Hitachi Hi-Tech Co., Ltd., and the transmittance at a wavelength of 380 nm was read. I did. In addition, the phase difference value was measured at a wavelength of 590 nm and 23 degreeC using the brand name "KOBRA21-ADH" manufactured by Oji Measuring Instruments Co., Ltd. The moisture permeability was measured under conditions of a temperature of 40°C and a relative humidity of 92% by a method according to JIS K 0208.

<Example 1>

30 parts of phenol novolac-based acrylate as curable compound (A) (manufactured by Hitachi Chemical Co., Ltd., product name ``Hitaroid UV251''), and oligomer of urethane acrylate as curable compound (B) (Mw = 2300, number of functional groups: 15) And dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name ``UA53H'') 70 parts and hydroxybutyl acrylate as monofunctional monomer (C) (manufactured by Osaka Organic Chemical Co., Ltd., product name ``4-HBA'') 20 parts, a leveling agent (manufactured by DIC, brand name: PC4100) 0.5 parts, and a photoinitiator (manufactured by Chiba Japan, brand name: Irgacure 907) are mixed, and methyl It diluted with isobutyl ketone, and the composition for hard coat layer formation was prepared.

On the base film A obtained in Production Example 1, the obtained composition for forming a hard coat layer was applied to form a coating layer, and the coating layer was heated at 75°C for 1 minute. The coating layer after heating was irradiated with ultraviolet rays with a cumulative amount of light of 300 mJ/cm 2 with a high-pressure mercury lamp to cure the coating layer to form a base layer, a hard coat layer, and a permeable layer to obtain an optical laminate.

<Example 2>

As the curable compound (A), an optical laminate was obtained in the same manner as in Example 1, except that 30 parts of an oligomer of fluorene-containing acrylate (manufactured by Osaka Gas Chemicals, product name "EA-HR034") was used.

<Example 3>

As the curable compound (A), an optical laminate was obtained in the same manner as in Example 1, except that 30 parts of an oligomer of fluorene-containing acrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name "HIC-GL") was used.

<Example 4>

An optical laminate was prepared in the same manner as in Example 1, except that 30 parts of ethoxylated o-phenylphenol (meth)acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name ``A-LEN-10'') was used as the curable compound (A). Got it.

<Example 5>

A phenol novolac-based acrylate (manufactured by Hitachi Chemical Co., Ltd., product name ``Hitaroid UV251'') is 50 parts, and a curable compound (B) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name ``UA53H'') is 50 parts , And except having changed the heating temperature to 65°C, it carried out similarly to Example 1, and obtained the optical laminated body.

<Example 6>

As the curable compound (A), 50 parts of a fluorene-containing acrylate oligomer (manufactured by Osaka Gas Chemicals, product name ``EA-HR034'') was used, and the curable compound (B) (manufactured by Shin-Nakamura Chemical Corporation, product name ``UA53H'') An optical laminate was obtained in the same manner as in Example 1, except that the blending amount was set to 50 parts and the heating temperature was set to 65°C.

<Example 7>

An optical laminate was obtained in the same manner as in Example 1, except that 30 parts of acryloylmorpholine (manufactured by Kojin Corporation, product name "ACMO") was used as the monofunctional monomer (C).

<Example 8>

As the monofunctional monomer (C), an optical laminate was obtained in the same manner as in Example 1, except that 30 parts of cyclohexanedimethanol monoacrylate (manufactured by Nippon Chemical Co., Ltd., product name "CHDMMA") was used.

<Comparative Example 1>

An optical laminate was obtained in the same manner as in Example 1, except that the curable compound (A) was not added and the amount of the curable compound (B) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name ``UA53H'') was set to 100 parts. .

<Comparative Example 2>

No curable compound (A) added, curable compound (B) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name ``UA53H'') of 100 parts, and hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., product name `` 4-HBA"), except that the compounding amount of 50 parts, was carried out in the same manner as in Example 1 to obtain an optical laminate.

<Comparative Example 3>

Except having not added the monofunctional monomer (C), it carried out similarly to Example 1, and obtained the optical laminated body.

<Comparative Example 4>

A phenol novolac-based acrylate (manufactured by Hitachi Chemical Co., Ltd., product name ``Hitaroid UV251'') is 50 parts, and a curable compound (B) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name ``UA53H'') is 100 parts , And except not having added the monofunctional monomer (C), it carried out similarly to Example 1, and obtained the optical laminated body.

<Comparative Example 5>

Examples except that 30 parts of an oligomer of fluorene-containing acrylate (manufactured by Osaka Gas Chemicals, product name ``EA-HR034'') was used as the curable compound (A), and a monofunctional monomer (C) was not added. It carried out similarly to 1, and obtained the optical laminated body.

<Comparative Example 6>

Optical lamination in the same manner as in Example 1 except that the blending amount of phenol novolac-based acrylate (manufactured by Hitachi Chemical Co., Ltd., product name ``Hitaroid UV251'') was set to 100 parts, and no curable compound (B) was added. I got a sieve.

Various properties of the optical laminates obtained in the above Examples and Comparative Examples were evaluated. The evaluation results are shown in Table 1 together with the composition of the composition for forming a hard coat layer.

As is also clear from Table 1, in the optical laminate of Examples, a permeable layer is preferably formed at a heating temperature of less than 80° C., and interference non-uniformity is not observed. In addition, the adhesion between the hard coat layer and the substrate layer is excellent, and the hardness is also excellent. On the other hand, in the optical laminates of Comparative Examples 1 and 2 obtained using the composition for forming a hard coat layer that does not contain an aromatic ring-containing curable compound (A), a permeable layer was formed, and interference non-uniformity was not observed. , The adhesion is insufficient. In addition, in the optical laminate obtained using the composition for forming a hard coat layer of Comparative Examples 3 to 5 that does not contain a monofunctional monomer (C), the formation of the permeable layer is insufficient, and as a result, there is a problem in adhesion and non-uniformity of interference. There is. In addition, in the optical laminated body of Comparative Example 6 obtained using the composition for hard coat layer formation which does not contain a polyfunctional curable compound (B), pencil hardness is H or less.

Industrial applicability

The optical laminate of the present invention can be suitably used for an image display device. The optical laminate of the present invention can be preferably used as a front plate of an image display device or a protective material for a polarizer, and in particular, it will be preferably used as a front plate of a liquid crystal display device (in particular, a three-dimensional liquid crystal display device). I can.

10; Base layer
20; Penetration layer
30; Hard coat layer
40; Block layer
100, 200, 300; Optical laminate

Claims (11)

A base layer formed from a (meth)acrylic resin film, and
A hard coat layer formed by coating a composition for forming a hard coat layer on the (meth)acrylic resin film,
A method for manufacturing an optical laminate comprising a permeable layer formed by infiltrating the (meth)acrylic resin film between the base layer and the hard coat layer, the composition for forming the hard coat layer,
The composition for forming a hard coat layer contains a curable compound (A) containing at least one radically polymerizable unsaturated group and an aromatic ring, and a curable compound containing at least two radically polymerizable unsaturated groups, but does not contain an aromatic ring ( B) and a monofunctional monomer (C) containing one radically polymerizable unsaturated group, but not containing an aromatic ring,
A method for producing an optical laminate comprising applying the composition for forming a hard coat layer on the (meth)acrylic resin film to form a coating layer, and heating the coating layer at 50°C or more and less than 100°C. The method of claim 1,
The method for producing an optical laminate, wherein the content ratio of the curable compound (A) to all curable compounds in the composition for forming a hard coat layer is 10% by weight to 60% by weight. The method of claim 1,
The method for producing an optical laminate, wherein the total content ratio of the curable compound (A) and the monofunctional monomer (C) to all curable compounds in the composition for forming a hard coat layer is 20% by weight to 70% by weight. The method of claim 1,
The method for producing an optical laminate, wherein the composition for forming a hard coat layer contains, as the curable compound (B), a curable compound (B1) containing 9 or more radically polymerizable unsaturated groups. The method of claim 1,
The method for producing an optical layered product, wherein the weight average molecular weight of the monofunctional monomer (C) is 500 or less. The method of claim 1,
The method for producing an optical laminate, wherein the monofunctional monomer (C) has a hydroxyl group. The method of claim 1,
The method for producing an optical laminate, wherein the (meth)acrylic resin forming the (meth)acrylic resin film has a structural unit expressing positive birefringence and a structural unit expressing negative birefringence. The method of claim 1,
The method for producing an optical laminate, wherein the weight average molecular weight of the (meth)acrylic resin forming the (meth)acrylic resin film is from 10000 to 500000. The method of claim 1,
The method for producing an optical laminate, wherein the composition for forming a hard coat layer contains fine particles having a weight average particle diameter of 1 µm to 30 µm. The method of claim 1,
The heating temperature of the coating layer is 50°C or more and less than 80°C. The method according to any one of claims 1 to 10,
The method for manufacturing an optical laminate, wherein the permeable layer has a thickness of 1.0 µm or more.

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