TW201700300A - Layered body - Google Patents

Abstract

The purpose of the present invention is to provide a novel layered body, which is a layered body that has an adhesive sheet and a front panel comprising a polycarbonate-based resin layer and a thermoplastic resin different from this polycarbonate-based resin, and that also has outstanding shape stability in a high-temperature and high-humidity environment. Provided is a layered body having a front panel and an adhesive sheet, the layered body being characterized in that: the front panel comprises a B layer having a polycarbonate-based resin as a principal constituent resin and an A layer having a thermoplastic resin different from the polycarbonate-based resin as a principal constituent; the total thickness of the A layer is 10-250 [mu]m, and the ratio ((A)/(T)) of the thickness (A) of one A layer to the total thickness (T) of the A layer and the B layer is 0.05-0.40; and the internal stress ([sigma]) of the front panel and the adhesive sheet when the layered body of the front panel and the adhesive sheet is exposed for 120 hours to an environment with a temperature of 85 DEG C and a humidity of 85% RH is 0.47 MPa or less.

Description

Laminated body

The present invention relates to a laminate. In detail, regarding a substrate material or a protective material, for example, a surface protection panel which can be preferably used as an image display device, or a housing material such as a mobile phone, a smart phone, a tablet device, a wearable terminal, or the like The layered body.

Since the beginning, as the outer casing material of the image display device, glass is mainly used. However, since glass is easily broken by impact and is heavy, research has been conducted on the use of a resin material instead of glass.

For such a resin material as a glass substitute material, impact resistance, surface hardness, and shape stability in a high-temperature and high-humidity environment are mainly required.

Since the polycarbonate resin sheet has transparency and is excellent in impact resistance or heat resistance, it is used for a sound insulating partition wall, a carport, a kanban, a reflective material, a lighting fixture, and the like. However, since the surface hardness is low, there is a disadvantage that it is easily damaged.

In order to improve the disadvantage, for example, Patent Document 1 discloses a resin laminate in which a laminate obtained by coextruding a polycarbonate resin and an acrylic resin is subjected to a hard coating treatment.

Further, as a method of suppressing the warpage of the polycarbonate resin sheet, for example, Patent Document 2 discloses a resin laminate in which a layer of a methyl methacrylate-styrene copolymer resin (MS resin) is laminated on a polycarbonate resin. body.

Similarly, as a method of suppressing warpage of a polycarbonate resin sheet, Patent Document 3 discloses that a polycarbonate resin is laminated to define a glass transition temperature difference of each layer. A resin laminate having a poor water absorption rate.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-103169

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-167659

[Patent Document 3] WO2014/061817

As described above, the front panel provided with the polycarbonate resin layer and the thermoplastic resin different from the polycarbonate resin is used as a surface protection for an image display device by laminating an adhesive sheet on a substrate or the like, for example. Panel or housing material. However, in the front panel, the polycarbonate resin and the thermoplastic resin different from the polycarbonate resin have different thermal expansion coefficients or hygroscopic properties, and thus have problems such as being placed in, for example, a high temperature and high humidity environment. Then, a resin layer absorbs moisture and changes in size, and it is difficult to maintain the shape stability of the front panel.

Therefore, the present invention relates to a laminate comprising a polycarbonate resin layer and a thermoplastic resin layer different from the polycarbonate resin, and an adhesive sheet, and is intended to provide a high temperature and high humidity environment. A novel laminate with excellent shape stability.

The present invention provides a laminate comprising a front panel and an adhesive sheet, wherein the front panel includes a B layer mainly composed of a polycarbonate resin, and the polycarbonate resin A thermoplastic resin A layer containing a different thermoplastic resin as a main component, the total thickness of the A layer is 10 to 250 μm, and the ratio of the thickness (A) of the A layer 1 layer to the total thickness (T) of the A layer and the B layer ((A)/(T)) is 0.05 to 0.40, and the laminate is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours by the following formulas (1) and (2). The internal stress (σ) of the front panel and the adhesive sheet is 0.47. Below MPa.

In the laminated body of the present invention, the total thickness of the thermoplastic resin A layer mainly composed of a thermoplastic resin different from the polycarbonate resin and the thickness of the A layer 1 layer are defined with respect to A in the configuration of the front panel. The ratio of the total layer thickness of the layer and the layer B ((A)/(T)), and the internal stress (σ) is set within a specific range, whereby the shape stability in an environment of high temperature and high humidity can be exhibited. performance.

Therefore, the laminate according to the present invention can be preferably used as a substrate material, a protective material, or the like, for example, by being bonded to a substrate or the like. In addition to various substrate materials or protective materials such as mobile phone terminals, smart phones, portable video game devices, portable information terminals, tablet devices, mobile personal computers, and wearable terminals, etc. It can also be preferably used as various substrate materials or protective materials for constituent materials of a display type display device such as a liquid crystal television, a liquid crystal display, a desktop personal computer, a car navigation, and an automobile instrument.

δ‧‧‧The height of the front end of the front panel from the static surface

L‧‧‧ sample length

ρ‧‧‧The radius of curvature of the front panel warped shape

θ‧‧‧The center of curvature from the warp shape of the front panel falls to the ground point of the front panel The perpendicular line and the angle between the center of curvature connecting the warped shape of the front panel and the end of the front panel

10‧‧‧ front panel

20‧‧‧Adhesive sheets

Figure 1 is a schematic diagram of a model for calculating internal stress.

Hereinafter, an example of an embodiment of the present invention will be described in detail.

In the present specification, the term "main component" of each layer means that the resin component forming the respective layers contains the resin component having the highest ratio (% by mass). The specific content is not specified, but as a standard, it is formed as a standard. 50% by mass or more, particularly 80% by mass or more, and more particularly 90% by mass or more (including 100% by mass) of the resin contained in the resin composition. Further, when the main component is two or more types The total amount of these is equivalent to the above content.

Further, the phrase "the main component" of the polymer and its derivative means the monomer having the highest proportion among the monomer units constituting the polymer and its derivative.

<This laminate>

The laminated body (hereinafter referred to as "the present laminated body") according to an embodiment of the present invention includes a front panel and an adhesive sheet, and is characterized as follows: in a specific exposure test, the front panel is The internal stress of the adhesive sheet is a specific range.

<front panel>

The front panel of the laminate may have a layer B of a polycarbonate resin as a main component and a thermoplastic resin layer A containing a thermoplastic resin different from the polycarbonate resin as a main component. As an example, the A layer including the resin containing the acrylic resin as a main component and the B layer including the resin containing the polycarbonate resin as a main component are mentioned.

Further, for example, a front panel formed by forming an A layer on one side or both sides of the B layer may be mentioned.

Here, the front panel preferably has characteristics such as transparency, rigidity, impact resistance, secondary workability, and high surface hardness.

<A layer>

The layer A is a layer mainly composed of a thermoplastic resin different from the above polycarbonate resin.

Here, "different" means a case where the type or composition ratio of the monomers constituting the polymer is different.

The thermoplastic resin which is a main component of the layer A is not particularly limited as long as it is different from the polycarbonate resin which is a main component of the layer B described below, and examples thereof include polyethylene terephthalate and poly Aromatic polyester such as ethylene naphthalate, polytrimethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate-1,4-cyclohexanedimethyl ester, and polylactic acid A polyester resin such as a polyester resin such as a polymer, a polyolefin resin such as polyethylene, polypropylene, or a cycloolefin resin, a polycarbonate resin, an acrylic resin, a polystyrene resin, or a polyamide. Resin, polyether resin, polyurethane resin, polyphenylene sulfide resin, polyester amide resin, polyether ester resin, vinyl chloride resin, acrylonitrile - styrene copolymer, acrylonitrile-butadiene-styrene copolymer, modified polyphenylene ether resin, polyarylate resin, polyfluorene resin, polyether quinone resin, polyamine An amine resin, a polyimide resin, a copolymer containing these as a main component, or a mixture of such resins. These may be one type or a mixture of two or more types.

In addition, the polycarbonate resin used as the main component of the layer A may be different from the polycarbonate resin which is a main component of the layer B described below, and examples thereof include aliphatic polycarbonate or fat. A cyclocarbonate, an aromatic polycarbonate containing bisphenol C, or the like.

Here, the present invention is not particularly limited. However, when the layer A is used as a surface layer, for example, it is preferred to select a resin having a hardness higher than that of the layer B. Specifically, the following acrylic resin (a1) or a polycarbonate resin (a3) having a specific structure can be used.

<Specific Configuration Example of Layer A>

As a preferable example of the A layer, a layer of a resin containing an acrylic resin (a1) as a main component is exemplified. Preferably, the layer A contains an acrylic resin (a1), and a copolymer (a2) having an aromatic vinyl monomer unit, a (meth) acrylate monomer unit, and an unsaturated dicarboxylic anhydride monomer unit. Floor.

Moreover, as another preferable example of the A layer, a layer containing a polycarbonate resin (a3) derived from a structural unit of a dihydroxy compound as a main component resin in one part of the structure may be mentioned.

Next, the respective component resins (a1) to (a3) will be described.

(acrylic resin (a1))

The acrylic resin (a1) is a (co)polymer and a derivative thereof obtained by polymerizing a (meth) acrylate monomer unit as a main component.

Here, the "(meth) acrylate monomer unit" means an acrylate monomer unit or a methacrylate monomer unit.

Examples of the (meth) acrylate monomer unit include methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylate. Isobutyl ester, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, (meth)acrylic acid Stearyl ester, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, (A) Base) hexyl acrylate, (meth) acrylate Base ester, (meth)acrylic acid drop Base ester, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofuran methyl (meth)acrylate, propylene oxime Base (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-(meth) propylene methoxyethyl succinate, 2-(methyl) propylene methoxyethyl maleate, 2-(Methyl)propenyloxyethyl phthalate, 2-(meth)acryloxyethyl hexahydrophthalate, pentamethylpiperidine (meth)acrylate, (A) Tetramethyl methacrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Further, examples of the other monomer unit which can be polymerized with the acrylic monomer units include an olefin monomer unit and a vinyl monomer unit.

Among them, from the viewpoint of lowering the internal stress, the acrylic resin (a1) can preferably use a methyl methacrylate monomer and a methacrylic acid monomer, an acrylic monomer, a maleic anhydride monomer, an aromatic vinyl group. a copolymer of any one or more of a monomer and an acrylonitrile monomer.

The stereoregularity of the acrylic resin (a1) is not particularly limited. However, the higher the ratio of the three-dimensional structure of the (meth) acrylate monomer unit to the row structure, the higher the glass transition temperature and the higher the heat resistance, which is preferable. From this point of view, a three-dimensional structure having the highest molar ratio of rr in mm, mr, and rr having a ternary component ratio can be preferably used. The ternary component ratio can be measured by a known method using a nuclear magnetic resonance measuring apparatus (1H-NMR).

(copolymer (a2))

As described above, the layer A preferably contains a layer of the above acrylic resin (a1) and copolymer (a2). Among them, it is preferred to mix the acrylic resin (a1) and the copolymer (a2) to form A. Floor.

The copolymer (a2) is a copolymer of an aromatic vinyl monomer unit, a (meth) acrylate monomer unit, and an unsaturated dicarboxylic anhydride monomer unit.

Examples of the "aromatic vinyl monomer unit" include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, 2,4-dimethyl styrene, and ethyl benzene. A unit of each styrene monomer such as ethylene, p-t-butylstyrene, α-methylstyrene, or α-methyl-p-methylstyrene. These aromatic vinyl monomer units may be used alone or in combination of two or more.

Among them, a styrene unit or an α-methylstyrene unit is preferred. Since the styrene monomer unit is industrially easy to obtain and economical, it is preferred that the α-methylstyrene monomer unit is preferred because it can increase the glass transition temperature.

Examples of the "(meth) acrylate monomer unit" include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid. Dicyclopentyl ester, methacrylic acid Each methacrylate monomer such as a base ester, and an acrylate monomer such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate or decyl acrylate unit. These (meth) acrylate monomer units may be used alone or in combination of two or more.

Among them, a methyl methacrylate monomer unit is preferred in terms of compatibility with the acrylic resin (a1), appearance, and the like.

Examples of the "unsaturated dicarboxylic anhydride monomer unit" include units derived from various anhydride monomers such as maleic anhydride, itaconic anhydride, citraconic anhydride, and aconitic anhydride. These unsaturated dicarboxylic anhydride monomer units may be used alone or in combination of two or more.

Among them, a maleic anhydride monomer unit is preferred in terms of compatibility with the acrylic resin (a1), transparency, and the like.

The constituent unit of the copolymer (a2) is preferably an aromatic vinyl monomer unit of 45 to 85% by mass, a (meth) acrylate monomer unit of 4 to 45% by mass, and an unsaturated dicarboxylic anhydride monomer. The unit is 8 to 20% by mass, more preferably 55 to 85% by mass of the aromatic vinyl monomer unit, 5 to 30% by mass of the (meth) acrylate monomer unit, and 10 to 18% by mass of the unsaturated dicarboxylic anhydride monomer unit. The range of %.

Further, the constituent unit of the copolymer (a2) can be qualitatively and quantitatively analyzed by a known method, for example, a nuclear magnetic resonance (NMR) measuring apparatus or another apparatus analyzing apparatus.

When the aromatic vinyl monomer unit in all the constituent units of the copolymer (a2) accounts for 45 mass% or more, particularly 55 mass% or more, the thermal stability is improved, and when the acrylic resin (a1) is mixed, good results can be obtained. The appearance, which in turn reduces water absorption, is preferred.

In addition, when the (meth) acrylate monomer unit in all the constituent units of the copolymer (a2) accounts for 4% by mass or more, particularly 5% by mass or more, compatibility with the acrylic resin (a1) is improved and transparent The sex becomes good, so it is better.

In addition, when the unsaturated dicarboxylic anhydride monomer unit in all the constituent units of the copolymer (a2) accounts for 8 mass% or more, particularly 10 mass% or more, the compatibility with the acrylic resin (a1) is improved, and transparency is improved. Or heat resistance is improved, so it is preferable.

On the other hand, when the ratio of the aromatic vinyl monomer unit in all the constituent units of the copolymer (a2) is 85% by mass or less, the miscibility with the acrylic resin (a1) can be maintained, and heat resistance or heat resistance can be improved. It is preferable to reduce water absorption and the like.

In addition, when the ratio of the (meth) acrylate monomer unit in all the constituent units of the copolymer (a2) is 45% by mass or less, particularly 30% by mass or less, compatibility with the acrylic resin (a1) can be ensured. It is preferable because it can suppress water absorption.

In addition, when the ratio of the unsaturated dicarboxylic anhydride unit in all the constituent units of the copolymer (a2) is 20% by mass or less, particularly 18% by mass or less, compatibility with the acrylic resin (a1) can be ensured, and It is preferred because it can improve thermal stability or inhibit water absorption.

The copolymer (a2) may contain "other copolymerizable" in addition to the above three monomer units, that is, an aromatic vinyl monomer unit, a (meth) acrylate monomer unit, and an unsaturated dicarboxylic anhydride monomer unit. unit". However, the content ratio thereof is preferably 5% by mass or less.

Examples of the "other copolymerizable unit" include an acrylonitrile monomer such as acrylonitrile or methacrylonitrile, a vinyl carboxylic acid monomer such as acrylic acid or methacrylic acid, and N-methyl maleimide. N-alkyl maleimide monomer such as N-ethyl maleimide, N-butyl maleimide, N-cyclohexylmaleimide, N-phenyl malayan A unit of each monomer such as an N-arylmaleimine monomer such as an amine, N-methylphenylmaleimide or N-chlorophenylmaleimide. These copolymerizable units may be used alone or in combination of two or more.

The polystyrene-equivalent weight average molecular weight (Mw) of the copolymer (a2) measured by gel permeation chromatography (GPC) is preferably from 100,000 to 200,000. When the weight average molecular weight (Mw) is in this range, the layer A obtained by mixing with the acrylic resin (a1) is excellent in moldability and appearance, and the like. From this point of view, a more preferred weight average molecular weight (Mw) ranges from 110,000 to 180,000.

The method for producing the copolymer (a2) can be produced by a known polymerization method, and is not particularly limited. For example, solution polymerization or bulk polymerization may be applied, and the polymerization process may suitably employ a batch type or a semi-batch type, a continuous type, or the like. In the present laminate, a batch polymerization process under solution polymerization can be preferably used in terms of less by-products and easy control of molecular weight adjustment and transparency.

((a1)/(a2))

In the layer A, the mixing quality of the acrylic resin (a1) and the copolymer (a2) is preferably (a1)/(a2)=80/20 to 20/80.

When the mixing ratio of the acrylic resin (a1) and the copolymer (a2) is within the above range, the adhesion to the layer of the layer B is excellent, and the surface hardness or transparency which is characteristic of the acrylic resin can be maintained, and heat resistance can be improved. It is preferred to inhibit or inhibit water absorption.

Further, in order to reduce the internal stress generated in the high-temperature and high-humidity environment of the laminate, it is preferably (a1)/(a2)=70/30 to 40/60, more preferably 70/30 to 60/40.

(polycarbonate resin (a3))

As described above, the layer A is also preferably composed of a polycarbonate resin (a3) having a specific structure as a main component. Thereby, the laminated body can be imparted with a high surface hardness.

Here, the polycarbonate resin (a3) is a polycarbonate resin containing a structural unit derived from a dihydroxy compound represented by the following (Chemical Formula 1) in a part of the structure.

Examples of the dihydroxy compound represented by the above (Chemical Formula 1) include isosorbide, isomannide, and isoidide in a relationship of a stereoisomer. These may be used alone or in combination of two or more.

The dihydroxy compound represented by the above (Chemical Formula 1) is an ether diol which can be produced from a saccharide using a biologically derived substance as a raw material. In particular, isosorbide can be produced inexpensively by hydrogenating D-glucose obtained from starch, followed by dehydration, and can be obtained abundantly as a resource. Based on these conditions, the best is isosorbide.

In the polycarbonate resin (a3) which is a main component of the layer A, the content of the structural unit derived from the dihydroxy compound represented by the above (Chemical Formula 1) is preferably 50 mol% or more, more preferably 60 mol%. The above is further preferably 90 mol% or less, more preferably 80 mol% or less.

The content ratio of the structural unit derived from the dihydroxy compound represented by the above (Chemical Formula 1) in the polycarbonate resin (a3) which is the main component of the A layer is in the above range, so the hardness of the polycarbonate resin (a3) is The intermediate value of the aromatic polycarbonate resin and the acrylic resin is drastically improved as compared with the front panel for a display in which the acrylic resin layer is disposed on the surface layer.

More specifically, since the content ratio of the structural unit is 90% by mole or less, surface hardness or heat resistance is excellent, and impact resistance and interlayer adhesion to the following B layer can be suppressed. Since it is reduced, it is possible to prevent various defects such as a decrease in yield during press working and breakage when handling a product as a front panel for a display.

On the other hand, since the content ratio is 50% by mole or more, the impact resistance and the press formability are excellent, and the reduction in surface hardness or heat resistance can be suppressed. Further, the laminated body can be preferably used for any of the front panel for display and the transparent building material by providing a hard coat layer on at least one side to obtain sufficient surface hardness.

The polycarbonate resin (a3) may have a structural unit other than the above structural unit, and examples thereof include a structural unit derived from an aliphatic dihydroxy compound described in International Publication No. 2004/111106, or International Publication No. 2007/ A structural unit derived from an alicyclic dihydroxy compound described in Japanese Patent Publication No. 148604.

Preferably, the structural unit derived from the aliphatic dihydroxy compound has a source selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexyl a structural unit of at least one dihydroxy compound in the group consisting of diols.

The structural unit derived from the alicyclic dihydroxy compound preferably contains a 5-membered ring structure or a 6-membered ring structure. The 6-member ring structure can also be fixed to a chair shape or a boat shape by a covalent bond. The heat resistance of the obtained polycarbonate can be improved by including a structural unit derived from an alicyclic dihydroxy compound as a 5-membered ring structure or a 6-membered ring structure. The number of carbon atoms contained in the alicyclic dihydroxy compound is usually preferably 70 or less, more preferably 50 or less, still more preferably 30 or less.

Examples of the alicyclic dihydroxy compound containing the above 5-membered ring structure or 6-membered ring structure include those described in the above-mentioned International Publication No. 2007/148604. Among them, cyclohexane dimethanol, tricyclodecane dimethanol, adamantane diol, and pentacyclopentadecane dimethanol are preferably exemplified.

Further, from the viewpoint of industrial availability, cyclohexane dimethanol is preferred, and among them, 1,4-cyclohexanedimethanol is preferred. On the other hand, in the case where heat resistance or interlayer adhesion to the layer B described below is important, tricyclodecane dimethanol is preferably selected.

The polycarbonate resin (a3) used in the above-mentioned layer A can be produced by a polymerization method generally used, and can be either a phosgene method or a transesterification method in which a reaction with a carbonic acid diester is carried out. Among them, a dihydroxy compound represented by the above (Chemical Formula 1), an aliphatic and/or alicyclic hydroxy compound, or other dihydroxy group used as needed in a part of the structure in the presence of a polymerization catalyst is preferred. A transesterification method in which a compound and a carbonic acid diester are reacted.

The transesterification method is a production method in which a dihydroxy compound represented by the above (Chemical Formula 1), an aliphatic and/or alicyclic hydroxy compound, other dihydroxy compounds used as needed, and carbonic acid are used in a part of the structure. The diester is added with a basic catalyst and an acidic substance neutralized by the basic catalyst to carry out a transesterification reaction.

Typical examples of the carbonic acid diester include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis(biphenyl) carbonate, and diethyl carbonate. Ester, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, and the like. Among these, it is particularly preferred to use diphenyl carbonate.

The molecular weight of the polycarbonate resin (a3) can be expressed by a specific viscosity. The lower limit of the specific viscosity is preferably 0.20 dl/g or more, more preferably 0.30 dL/g or more, and still more preferably 0.35 dL/g. The upper limit of the rich viscosity is preferably 1.20 dL/g or less, more preferably 1.00 dL/g or less, still more preferably 0.80 dL/g or less.

When the specific viscosity of the polycarbonate resin is too low, the mechanical strength of the molded article may be small. If the viscosity is too large, the fluidity at the time of molding may be lowered, and the productivity or moldability tends to be lowered.

(other ingredients)

The layer A may appropriately contain various additives, modifiers, and the like within a range that does not impair the effects of the present invention. Here, examples of the additive include an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, a flame retardant, and a colorant. Moreover, examples of the modifier include an impact resistance improver, a compatibilizer, and an antistatic agent.

<B layer>

The B layer has a layer which functions as a function of impact resistance or heat resistance among the functions of the laminate.

In the layer B, the polycarbonate resin (b1) may be used as the main component resin alone, or the following various modifiers (b2) may be mixed in the polycarbonate resin (b1) to be used as the main component resin.

(Polycarbonate resin (b1))

Examples of the polycarbonate resin (b1) include an aromatic polycarbonate resin and an aliphatic polycarbonate resin.

The polycarbonate resin (b1) may be a homopolymer or a copolymer with other copolymerizable monomers.

Further, the structure of the polycarbonate resin (b1) may be a branched structure, a linear structure, or a mixture of a branched structure and a linear structure.

In addition, the polycarbonate resin (b1) can be obtained by any known production method such as a phosgene method, a transesterification method, or a pyridine method.

The weight average molecular weight of the polycarbonate resin (b1) may be 10,000 to 100,000, and preferably 20,000 or more, or more preferably 40,000 or less, and more preferably 22,000 or more and 28,000 or less.

The polycarbonate resin (b1) may be used alone or in combination of two or more kinds having different weight average molecular weights.

When the weight average molecular weight of the polycarbonate resin (b1) is in the above range, impact resistance can be ensured and extrusion formability is also good, which is preferable.

(modifier (b2))

In order to adjust the melt viscosity, increase the hardness, and the like, it is preferred to mix the polycarbonate resin (b1) and the modifier (b2) for the formation of the layer B.

As the modifier (b2), a specific acrylic resin (b2) can be exemplified.

(acrylic resin (b2))

The acrylic resin (b2) is preferably an acrylic copolymer containing 5 to 80% by mass of an aromatic (meth) acrylate monomer unit and 95 to 20% by mass of a methyl methacrylate monomer unit.

When the content ratio of the aromatic (meth) acrylate monomer unit to the methyl methacrylate monomer unit in the acrylic resin (b2) is within the above range, the polycarbonate resin (b1) can be expressed. It is preferable because the compatibility or the surface hardness is improved.

From this point of view, it is more preferably 10 to 70% by mass of the aromatic (meth) acrylate monomer unit and 90 to 30% by mass of the methyl methacrylate monomer unit, and more preferably aromatic (methyl). The acrylate monomer unit is 25 to 60% by mass and the methyl methacrylate monomer unit is 75 to 40% by mass.

Examples of the aromatic (meth) acrylate monomer unit include phenyl (meth) acrylate and benzyl (meth) acrylate. These may be used alone or in combination of two or more.

Among them, phenyl methacrylate or benzyl methacrylate is preferred from the viewpoint of compatibility with the polycarbonate resin (b1), and more preferably phenyl methacrylate.

The acrylic resin (b2) may contain other monomer units copolymerizable than the aromatic (meth) acrylate monomer unit and the methyl methacrylate monomer unit, as needed.

When the acrylic resin (b2) contains another monomer unit, the other monomer unit in the acrylic resin (b2) is preferably 0.1 to 10% by mass.

The polystyrene-equivalent weight average molecular weight (Mw) of the acrylic resin (b2) measured by gel permeation chromatography (GPC) is preferably 5,000 to 30,000.

When the weight average molecular weight (Mw) of the acrylic resin (b2) is in the above range, the compatibility with the polycarbonate resin (b1) is good, and the formability, surface hardness improvement effect, appearance, and the like of the obtained B layer are good. Excellent, so it is better.

From this point of view, the weight average molecular weight (Mw) of the acrylic resin (b2) is more preferably in the range of 10,000 to 28,000.

The mass ratio of the mixture of the polycarbonate resin (b1) and the acrylic resin (b2) is not particularly limited, and is preferably (b1)/(b2)=99 to 65/1 to 35. When the mixing ratio of the two is within this range, the obtained layer B is excellent in moldability, surface hardness improving effect, appearance, and the like, and is therefore preferable.

From this point of view, it is more preferable that (b1) / (b2) = 95/5 to 70/30.

(preferably polycarbonate resin)

In the above description, from the viewpoint of reducing the internal stress generated in the high-temperature and high-humidity environment of the laminate, the polycarbonate resin-based glass which is the main component resin of the B layer has a higher transition temperature, and is preferably better. A homopolymer of a polycarbonate resin (b1) is used. On the other hand, when the surface hardness of the laminated body is important, the polycarbonate resin (b1) and the modifying agent (b2) are preferably contained.

(other ingredients)

The layer B can be formulated with various additives or other resins as described above within a range not impairing the effects of the present invention.

Examples of the additive include an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, a flame retardant, a colorant, an anti-hydrolysis agent, and the like.

(glass transition temperature of each layer)

The smaller the difference between the glass transition temperature of the layer A and the glass transition temperature of the layer B, the better, preferably from 100 to 140 ° C, more preferably 110, from the viewpoint of suppressing internal stress generated in a high-temperature and high-humidity environment. °C or more or 140 °C or less, more preferably 115 ° C or more, and still more preferably 120 ° C or more.

On the other hand, from the viewpoint of suppressing the internal stress generated in a high-temperature and high-humidity environment, the glass transition temperature of the layer B is preferably as high as possible, preferably from 100 ° C to 160 ° C, and further preferably more than 120 ° C or Below 155 °C.

Moreover, if the absolute value of the difference between the glass transition temperature of the layer A and the glass transition temperature of the layer B is 30 ° C or less, the high temperature and high humidity ring having a temperature of 85 ° C and a humidity of 85% RH can be further suppressed. It is better to warp the panel before the test. From this point of view, the absolute value of the difference is preferably 30 ° C or less, more preferably 20 ° C or less, further preferably 10 ° C or less, and further preferably 5 ° C or less.

It is considered that the reason is that in the high-temperature and high-humidity environment, the layer A is softened by the water absorption, and the temperature is lowered. Therefore, if the absolute value of the difference is within the above range, the temperature is high and high. In the environment, the dimensional change behavior of the two layers is close, and as a result, the warpage is suppressed.

In addition, the glass transition temperature is a value obtained by measuring with a differential scanning calorimeter in accordance with JIS K7111 at a heating rate of 10 ° C /min. However, the glass transition temperature can also be measured by other known machine analysis devices, such as dynamic viscoelastic devices.

<hard coating (layer C)>

The front panel may further have a hard coat layer (C layer) as the outermost layer on one side or both sides. However, it is also possible not to have a hard coat layer (C layer).

The hard coat layer (C layer) is a layer that imparts excellent surface hardness or scratch resistance to the front panel.

The hard coat layer (C layer) can be formed by, for example, curing the curable resin composition for forming a C layer by irradiation with an energy beam such as an electron beam, radiation, or ultraviolet rays, or curing the curable resin composition for forming a C layer by heating. .

In the viewpoint of molding time and productivity, it is preferred to form a hard coat layer (C layer) by curing the curable resin composition for forming a C layer by irradiation with ultraviolet rays.

The curable resin composition for forming a C layer for forming a hard coat layer (C layer) may be a resin composition containing the curable resin C1. When the curable resin composition for forming a C layer is cured by irradiation with ultraviolet rays as described above, the curable resin composition for forming a C layer preferably contains a photopolymerization initiator in addition to the curable resin C1. A resin composition.

As a specific example of the above-mentioned curable resin C1, for example, an acrylate compound can be exemplified , acrylate urethane compound, epoxy acrylate compound, carboxyl modified epoxy acrylate compound, polyester acrylate compound, copolymer acrylate, alicyclic epoxy resin, glycidyl ether epoxy resin, A vinyl ether compound, an oxetane compound, or the like. These curable resins may be used alone or in combination of two or more.

Examples of the curable resin C1 that imparts a more excellent surface hardness include a polyfunctional acrylate compound, a polyfunctional urethane urethane compound, a polyfunctional epoxy acrylate compound, and the like, and a radical polymerizable curable compound, or An organic or inorganic complex curable resin composition in which the curable resin contains an inorganic component, such as an alkoxy decane or an alkyl alkoxy decane, and a thermopolymerizable curable compound.

An organic or inorganic mixed curable resin composition is exemplified as the curable resin composition for forming a C layer which is particularly excellent in surface hardness. The organic-inorganic hybrid-curable resin composition includes a curable resin composition containing an inorganic component having a reactive functional group in the curable resin.

By using such an inorganic component having a reactive functional group, for example, an organic or inorganic composite system in which the inorganic component and the radical polymerizable monomer are copolymerized and crosslinked, and the organic binder alone contains an inorganic component The hardenable resin composition is less likely to cause hardening shrinkage and exhibits a higher surface hardness, which is preferable. Furthermore, as a more preferable example, an organic or inorganic mixed curable resin composition containing a UV-reactive colloidal ceria as an inorganic component having a reactive functional group is mentioned as a preferable example.

In order to impart particularly excellent surface hardness to the hard coat layer (C layer), it is preferred to adjust the concentration of the inorganic component contained in the hard coat layer (C layer), particularly the inorganic component having a reactive functional group.

From this point of view, the concentration of the inorganic component contained in the hard coat layer (C layer), particularly the inorganic component having a reactive functional group, is preferably 10 to 65% by mass. When the concentration is 10% by mass or more, excellent surface hardness can be obtained for the hard coat layer (C layer). Therefore, it is better. On the other hand, when the concentration is 65% by mass or less, the inorganic component, particularly the inorganic component having a reactive functional group, can be most densely packed in the hard coat layer (C layer), and the surface hardness can be effectively imparted. Therefore, it is better.

From this point of view, the concentration is preferably from 10 to 65% by mass, more preferably from 20% by mass to 60% by mass, and further preferably from 40% by mass to 55% by mass.

Further, from the viewpoint of improving the adhesion to the adhesive sheet described below and reducing the internal stress generated in the high-temperature and high-humidity environment of the laminate, the main component resin of the hard coat layer (C layer) is preferably The same resin as the main component resin of the adhesive sheet. For example, when the main component resin of the adhesive sheet is an acrylic resin, the main component resin of the hard coat layer (C layer) is preferably an acrylic resin.

The curable resin composition for forming a layer C preferably contains a photopolymerization initiator which is excited and activated by absorption of ultraviolet rays to cause a polymerization reaction to cause a curing reaction of the ultraviolet curable resin.

Examples of the photopolymerization initiator include benzophenone, benzophenone or a derivative thereof, and 9-oxosulfuric acid. Classes, benzoin dimethyl ketals, α hydroxyalkyl phenones, α-hydroxyacetophenones, hydroxy ketones, aminoalkyl phenones, fluorenyl phosphine oxides, and the like. Among them, α-hydroxyalkylphenones are less likely to cause yellowing upon hardening, and a transparent cured product can be obtained, which is preferable. Further, the aminoalkyl benzophenones are preferred because they have a very high reactivity and can obtain a cured product having excellent hardness. The photopolymerization initiator may be used alone or in combination of two or more.

The amount of the photopolymerization initiator to be added is preferably 0.1 to 5 parts by mass based on 100 parts by mass of the curable resin.

The curable resin composition for forming a C layer may contain a leveling agent as a surface conditioning component.

Examples of the leveling agent include an anthrone-based leveling agent and an acrylic leveling agent. Among them, those having a reactive functional group at the terminal are preferred, and more preferably having two or more functional groups. Reactive functional group.

Specifically, a polyether-modified polydimethylsiloxane having an acrylic group having a double bond at both terminals, or a poly(acrylic acid group having two double bonds at the terminal and having a total of four double bonds) Ester-modified polydimethyl siloxane or the like.

Among these, an acrylic-modified polyester-modified polydimethyl siloxane having a stable haze value and contributing to an improvement in scratch resistance is particularly preferable.

In addition to the curable resin component, the curable resin composition for forming a C layer may contain, for example, a ruthenium compound, a fluorine compound, or a lubricant such as a mixed compound, or an antioxidant, insofar as the effects of the present invention are not impaired. Various additives such as a flame retardant such as an ultraviolet absorber, an antistatic agent, and an anthrone compound, a filler, a glass fiber, and an impact modifier.

The thickness of the above hard coat layer (C layer) is not particularly limited. For example, it is preferably 1 μm to 30 μm, more preferably 3 μm or more or 25 μm or less, and further preferably 5 μm or more or 20 μm or less, and particularly preferably 7 μm or more or 15 μm or less.

Here, when the thickness of the hard coat layer (C layer) is in the above range, scratch resistance can be imparted, and cracking due to stress is less likely to occur, which is preferable.

Further, in the case where the hard coat layer (C layer) is provided on both sides, the thickness of each of the hard coat layers may be the same or different. Preferably, the thickness of each hard coat layer is in the range of 7 μm to 15 μm, and the thickness of the hard coat layer on the surface of the acrylic resin layer (layer A) is equal to or larger than the surface of the polycarbonate resin layer (layer B). The thickness of the hard coat layer.

<Layer of front panel>

The front panel may have a layer structure of a thermoplastic resin layer (layer A) different from the polycarbonate resin on one side or both sides of the polycarbonate resin layer (layer B), and may have another layer. . For example, a layered body having an acrylic resin layer (layer A) on one side or both sides of the polycarbonate resin layer (layer B) may be provided, and other layers may be provided.

Further, for example, as described above, the outermost surface of the one-sided side or the outermost surface of both sides may be provided. Hard coating (layer C).

As the layer constitution of the front panel, (A) / (B), (A) / (B) / (A), (C) / (A) / (B), (C) / (A) / ( B) / (A), (C) / (A) / (B) / (C), and (C) / (A) / (B) / (A) / (C).

Here, in the case where the layer has the same classification layer of two or more layers, the layer may have the same composition or a different composition.

In the above description, it is preferably (A) / (B), (A) / (B) / (A), (C) / (A) / (B), (C) / (A) / (B) /(C), (C)/(A)/(B)/(A)/(C).

Further, in the case of a display panel or the like, it is more preferable to arrange it as (viewing side) (C)/(A)/(B)/(C) (light source side) or (visual side) (C)/(A) ) / (B) (light source side).

<thickness of front panel>

The front panel, the thickness (a ₁₎ of the front panel is not particularly limited, is preferably 0.1mm ~ 3.0mm, more preferably 1.5mm or less wherein, further preferably wherein more than 0.15mm 1.2mm or less.

Moreover, the thickness (a ₁ ) of the front panel also has a preferred range depending on the application of the laminate. For example, in the case of the outer casing material applied to various image display devices, it is preferably 0.1 to 2.0 mm, more preferably 0.15 mm or more or 1.5 mm or less, 0.2 mm or more, 0.8 mm or less, 0.2 mm or more, or 0.7. Below mm. If it is in this range, it is preferable because it is excellent in the shape stability in the environment of light weight, rigidity, and high temperature or high humidity.

Further, in the case where an adhesive layer or the like is laminated on the front panel and applied to the surface of the protective glass or the like without causing stains or damage, or the use of scattering of broken pieces or the like, the thickness (a ₁ ) of the front panel is preferably 0.1. Mm~0.6mm, more preferably 0.15mm or more or 0.5mm or less.

The thickness (a ₁ ) of the front panel is preferably thinner in terms of reducing the internal stress (σ) of the laminate regardless of the use. From this point of view, the thickness (a ₁ ) of the front panel is preferably 0.7 mm or less, more preferably 0.6 mm or less, still more preferably 0.5 mm or less.

In the laminate, in order to suppress the internal stress and shape stability generated in the high-temperature and high-humidity environment of the laminate, the total thickness of the A layer is preferably as small as possible, but on the other hand, in order to increase the surface hardness, it is preferably A certain thickness or more is preferably adjusted to an appropriate range according to the physical properties of the target.

From this point of view, the total thickness of the layer A is preferably from 10 μm to 250 μm, more preferably from 30 μm to 200 μm, and further preferably from 50 μm to 150 μm.

In the case where the laminate has two layers as the A layer, for example, the total thickness of the two layers is the total thickness of the A layer.

Further, from the viewpoint of reducing the internal stress of the laminate and improving the shape stability in a high-temperature and high-humidity environment, the thickness (A) of the thermoplastic resin layer A layer 1 layer is relative to the thermoplastic resin layer A layer and the polycarbonate system. The ratio ((A)/(T)) of the total thickness (T) of the resin layer B layer is preferably 0.05 to 0.40, more preferably 0.07 or more or 0.35 or less, and further preferably 0.10 or more or 0.30 or less.

Further, in the case where the two-layer A layer is provided, in order to eliminate the difference in the expansion and contraction behavior between the A layer and the B layer on the front and back sides, the thickness of each of the A layers is preferably set to be the same thickness.

<Elastic Modulus of Front Panel>

The elastic modulus (E ₁ ) of the front panel is preferably 1500 to 4500 (MPa), and more preferably 1800 or more, from the viewpoint of reducing the internal stress in the high-temperature and high-humidity environment of the laminate and improving the shape stability. Or 4,000 (MPa) or less, and further preferably 2,000 or more and 3,500 (MPa) or less.

<the amount of warpage of the front panel>

From the viewpoint of reducing the internal stress of the laminate and improving the shape stability in a high-temperature and high-humidity environment, the front panel is allowed to stand in an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, followed by a temperature of 23 ° C. 4, after 4 hours of humidity, 50% RH The average value of the amount of warpage of the corners is preferably 1.5 mm or less, more preferably 1.0 mm or less, and particularly preferably 0.3 mm or less.

On the other hand, even when the amount of warpage (δ) is large to some extent, the inside of the laminate can be made thin by reducing the thickness of the front panel, reducing the elastic modulus of the adhesive sheet, and the like. The stress (σ) is adjusted to a specific range to improve the shape stability in a high temperature and high humidity environment.

The lower limit of the warpage amount (δ) is preferably 0.01 mm or more, and more preferably 0.05 mm or more from the viewpoint of industrial productivity or yield of the front panel.

In order to adjust the above-mentioned warpage amount (δ) of the front panel to the above range, it is preferable to reduce the total thickness of the A layer and adjust the thickness of the A layer 1 layer (A) with respect to the total of the A layer and the B layer. The method of the ratio of the layer thickness (T) ((A)/(T)), or the method of obtaining the balance of the elastic modulus, the hardening shrinkage amount, and the thickness of the hard coat layer on the front side. However, it is not limited to these methods.

<Manufacturing method of front panel>

As a film forming method in which the A layer and the B layer are laminated, a known method can be employed. From the viewpoints of workability or productivity, etc., it is preferable to use a melt mixing apparatus having, for example, a single-axis extruder, a multi-axis extruder, a Banbury mixer, a kneader, and the like, and using a T-die extrusion Casting method.

As the lamination method, a method of co-extruding a melt-kneaded resin by a T-die having a feed module or a multi-manifold can be preferably used.

In order to make the appearance of the laminated body good, it is preferable to use a forming roll (metal elastic roll or polishing roll, etc.) whose surface is mirror-finished.

The molding temperature in the extrusion casting method using the T-die is appropriately adjusted depending on the flow characteristics, film forming properties, and the like of the resin composition to be used, and is approximately 300 ° C or lower, preferably 230 to 260 ° C. The forming roll temperature is approximately 90 to 160 ° C, preferably 95 to 150 ° C.

Further, in the case of extruding each layer, a single-axis extruder or a multi-axis extruder can be preferably used, and it is preferable to have an exhaust function and a filtering function for the extruder of each layer. Exhaust function It is preferable to use a dry or a small amount of a volatile component in the resin composition used in each layer to remove a layered body having few defects such as bubbles. Further, there are various methods for the filtration function, and specific examples thereof include a leaf disc filter, a chassis filter, a cone filter, a candle filter, a cylindrical filter, and the like. Among them, a leaf disc filter which is easy to ensure an effective filtration area is preferable. By the filtration function, it is preferable to remove a foreign matter, a microgel or the like, and to obtain a laminate having less appearance defects.

Further, the resin composition for forming each layer may be used by mixing the components in advance by a mixer such as a tumbler mixer, a V-type mixer, a Banbury mixer, or an extruder, or may be metered. Each component is directly supplied to the supply port of the extruder, or further, the separately metered components are supplied to the respective supply ports of the extruder having two or more supply ports.

Further, a known method can be used for the mixing method of various additives. For example, (a) a masterbatch obtained by mixing various additives at a high concentration (about 3 to 60% by mass as a representative content) in an appropriate base resin, and mixing the master batch into A method of adjusting the concentration in the resin to be used; (b) a method of directly mixing various additives in the resin to be used, and the like.

A method of dissolving or dispersing the curable resin composition for forming a C layer in an organic solvent by coating the surface of the layer A or the layer B (referred to as "the surface of the resin layer") which is laminated as described above. After the coating, a cured film is formed, whereby it is formed and laminated on the surface of the resin layer. However, it is not limited to this method.

As a method of the surface layer of the resin layer, a known method can be used. For example, a lamination method using a cover film, a dip coating method, a direct coating method, a reverse coating method, a kama coating method, a roll coating method, a spin coating method, a wire bar coating method, and extrusion may be mentioned. Coating method, curtain coating method, spray coating method, gravure coating method, and the like. Further, for example, a method of forming a transfer sheet formed by forming a hard coat layer (C layer) on a release layer, and laminating the hard coat layer (C layer) on the surface of the resin layer may be employed.

Further, in order to improve the adhesion between the hard coat layer (C layer) and the surface of the resin layer, the resin may be added. The surface of the layer is subjected to various surface treatments such as corona treatment or plasma treatment and primer treatment.

In addition, after the curable resin composition is formed on the resin layer surface area layer C layer, the curable resin composition is cured by irradiation with an energy ray such as an electron beam, radiation, or ultraviolet rays, or by heating. The curable resin composition is cured. Among them, from the viewpoint of molding time and productivity, it is preferred to be cured by ultraviolet irradiation.

Here, as the light source that emits ultraviolet light, for example, an electrodeless high pressure mercury lamp, an electrode high pressure mercury lamp, an electrodeless metal halide lamp, an electrode metal halide lamp, a xenon lamp, an ultrahigh pressure mercury lamp, or a mercury xenon lamp can be used. Among them, the electrodeless high-pressure mercury lamp is easy to obtain high-intensity ultraviolet rays, and is advantageous for hardening of the ultraviolet curable resin, which is preferable.

When the curable resin composition for forming a C layer contains an ultraviolet curable resin and is cured by irradiation with ultraviolet rays, since the transparency of ultraviolet rays is high, there is a case where the inside of the curable resin composition hardens rapidly. However, the surface hardening of the curable resin composition is slow due to the hardening action by oxygen (referred to as oxygen inhibition). In the oxygen barrier, when the resin composition is placed under a nitrogen atmosphere by the supply of nitrogen gas, and then ultraviolet rays are irradiated, the surface of the resin composition can be hardened together with the hardening of the inside, which is preferable.

The resin laminate may be heat-treated by laminating a thermoplastic resin layer (layer A) on one side or both sides of the polycarbonate resin layer (layer B) to form a resin laminate.

As the heat treatment condition, it is preferably in a temperature region lower than the glass transition temperature of the layer A by 5 ° C to 30 ° C, especially in a temperature region of 5 ° C to 25 ° C lower, especially in a temperature region of 5 ° C to 20 ° C lower. The resin laminate is subjected to heat treatment.

Further, the outermost surface of the single-sided side or both sides of the front panel may be subjected to any one of anti-reflection treatment, anti-fouling treatment, antistatic treatment, weather resistance treatment, and anti-glare treatment.

The method of each treatment is not particularly limited, and a known method can be used. For example, a method of applying a reflection reducing paint, a method of vaporizing a dielectric film, and applying an antistatic coating can be exemplified. Method and so on.

<Adhesive sheet>

The composition of the adhesive sheet used in the laminate is not particularly limited. However, from the viewpoints of adhesion, transparency, weather resistance, and the like, it is preferred to use an adhesive sheet obtained by crosslinking an adhesive composition containing an acrylic resin as a main component resin.

(adhesive composition)

The pressure-sensitive adhesive composition preferably contains an acrylic resin, a crosslinking monomer, a crosslinking initiator which is used as needed, a reaction catalyst, and the like.

As the acrylic resin used as the main component resin, an acrylate polymer (including a copolymer) is preferable.

The acrylate polymer (including the copolymer) can be appropriately adjusted in glass transition temperature by the kind, composition ratio, polymerization condition, and the like of the acrylic monomer or the methacrylic monomer to be polymerized into the acrylate polymer ( Tg) and other characteristics.

Examples of the acrylic monomer or methacrylic monomer to be polymerized into an acrylate polymer include 2-ethylhexyl acrylate, n-octyl acrylate, n-butyl acrylate, ethyl acrylate, and methacrylic acid. Methyl ester, etc. Vinyl acetate, hydroxyethyl acrylate, acrylic acid, glycidyl acrylate, acrylamide, acrylonitrile, methacrylonitrile, fluoroacrylate, which are copolymerized with a hydrophilic group or an organic functional group or the like, may also be used. , anthrone acrylate, and the like.

Among the acrylate polymers, a (meth)acrylic acid alkyl ester copolymer is particularly preferred.

As a (meth) acrylate for forming an alkyl (meth) acrylate-based copolymer, that is, an alkyl acrylate or an alkyl methacrylate component, the alkyl group is preferably an n-octyl group or an isooctyl group. Or one of alkyl acrylate or alkyl methacrylate of any one of 2-ethylhexyl, n-butyl, isobutyl, methyl, ethyl or isopropyl or selected from the group consisting of A mixture of two or more kinds.

As other ingredients, organic officials such as carboxyl groups, hydroxyl groups, and glycidyl groups can also be used. Copolymer acrylate or methacrylate copolymerization. Specifically, a monomer component obtained by selectively combining the (meth)acrylic acid alkyl ester component and the (meth)acrylic acid ester component having an organic functional group as a starting material can be obtained by heat polymerization ( Methyl) acrylate copolymer polymer.

Preferred examples thereof include one of an alkyl acrylate such as isooctyl acrylate, n-octyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate; or a mixture of two or more selected from the group consisting of, or At least one or more of isooctyl acrylate, n-octyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like are copolymerized with acrylic acid.

As the crosslinking monomer (also referred to as "crosslinking agent"), a polyfunctional (meth) acrylate having two or more (meth) acrylonitrile groups, two or more isocyanate groups, and epoxy can be used. A polyfunctional organofunctional resin having an organic functional group such as a melamine group, a diol group, a decyloxy group or an amine group; or an organometallic compound having a metal complex of zinc, aluminum, sodium, zirconium, calcium or the like.

Examples of the above polyfunctional (meth) acrylate include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,9-nonanediol diacrylate. , trimethylolpropane triacrylate, and the like.

The content of the crosslinking monomer may be adjusted in accordance with other elements so as to obtain a desired holding strength, and is usually 0.01 to 40.0 parts by mass, preferably 0.1 to 30.0 parts by mass based on 100 parts by mass of the main component resin. It is particularly preferred to adjust the ratio within a range of from 0.5 to 30.0 parts by mass. However, it is also possible to exceed this range on the condition that it is balanced with other elements.

When the acrylate polymer is crosslinked, a crosslinking initiator (peroxidation initiator, photoinitiator) or a reaction catalyst (a tertiary amine compound, a quaternary ammonium compound, a laurel) is appropriately added. Acid tin compounds, etc.) are more effective.

In the case of ultraviolet irradiation crosslinking (also referred to as "UV (Ultraviolet) crosslinking), it is preferred to formulate a photoinitiator.

As the photoinitiator, either a cleavage type photoinitiator or a hydrogen abstraction type photoinitiator can be used, or both can be used in combination.

Examples of the cleavage type photoinitiator include benzoin butyl ether, benzoin dimethyl ketal, hydroxyacetophenone, and the like.

On the other hand, examples of the hydrogen abstraction type photoinitiator include benzophenone, mischrone, dibenzocycloheptanone, 2-ethyl fluorene, isobutyl 9-oxosulfuric acid. Wait.

However, it is not limited to the above-mentioned substances.

The amount of the photoinitiator to be added is usually adjusted as appropriate within a ratio of 0.05 to 5.0 parts by mass based on 100 parts by mass of the main component resin, and is preferably 1: The proportion of 1 is combined with the photo-initiating agent of the hydrogen abstraction type and the cleavage type. However, it is also possible to exceed this range in order to achieve a balance with other elements.

(other additives)

In addition to the above components, a pigment such as a pigment or a dye having near-infrared absorption characteristics, an adhesion-imparting agent, an antioxidant, an anti-aging agent, a moisture absorbent, an ultraviolet absorber, a decane coupling agent, a natural substance or Various additives such as resin, glass fiber or glass beads of the composition.

In the above-mentioned adhesive sheet, an adhesive sheet can be prepared by adding an acrylic resin as a main component resin, a crosslinking agent, a reaction initiator or a reaction catalyst, which are optionally used, and stirring and mixing. The film is formed on the release film so as to have a desired thickness, and is subjected to heat drying or ultraviolet irradiation to be crosslinked.

(thickness)

The thickness (a ₂ ) of the adhesive sheet is preferably from 10 μm to 300 μm, particularly preferably from 30 μm to 250 μm, from the viewpoint of reducing the internal stress of the laminate and improving the shape stability in a high-temperature and high-humidity environment. More preferably, it is 50 μm or more or 200 μm or less.

(elastic modulus)

The elastic modulus (E ₂ ) of the adhesive sheet is preferably 0.001 MPa or more from the viewpoint of improving the shape stability in a high-temperature and high-humidity environment. From this viewpoint, it is more preferably 0.01 MPa or more, and still more preferably 0.1 MPa or more.

Further, from the viewpoint of improving the tackiness and the like, the elastic modulus (E ₂ ) is preferably 30 MPa or less, more preferably 20 MPa or less, still more preferably 10 MPa or less.

The so-called touch stick is defined as "the person who expresses the adhesion with the moment when the body is adhered to the body". "There are more cases of qualitative judgment by fingers, etc." (High performance followed by Kimura Hiroshi, Iwakawa Sei and others) Agent, Adhesive" Kyoritsu Publishing Co., Ltd. issued on February 20, 1989)

Further, the elastic modulus (E ₂ ) of the adhesive sheet can be measured by performing a tensile test at a test speed of 300 mm/min along the longitudinal direction of the cut adhesive sheet using a tensile tester.

(Tg)

The Tg of the adhesive sheet can be a rheometer ("MARS" manufactured by Yinghong Seiki Co., Ltd.) on the adhesive jig: Φ25 mm parallel plate, strain: 0.5%, frequency: 1 Hz, temperature: -50 to 200 ° C, heating rate: The loss tangent (tan δ) of the dynamic viscoelasticity measurement by the shearing method was measured at 3 ° C/min.

<Characteristics of this laminate>

This laminate is characterized in that the laminate of the front panel and the adhesive sheet is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours by the following formulas (1) and (2). The internal stress (σ) of the front panel and the adhesive sheet at the time is 0.47 MPa or less.

Here, the meaning of each character in the above formulas (1) and (2) is as follows.

δ: In the front panel warp shape when the front panel is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, the front panel is left horizontally in a downwardly convex shape. Height of self-standing surface

L: sample length (10cm)

θ: in the front panel warp shape when the front panel is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, the front panel is horizontally placed in a downwardly convex shape from the front panel The angle between the center of curvature of the warped shape falling to the ground point of the front panel and the line connecting the center of curvature of the warped shape of the front panel to the end of the front panel

ρ ₁ : Curvature radius of the front panel warp shape when the front panel is exposed to an environment of temperature 85 ° C and humidity 85% RH for 120 hours.

a ₁ : thickness of the front panel

a ₂ : thickness of the adhesive sheet

b: sample width (10cm)

E ₁ : the modulus of elasticity of the front panel

E ₂ : elastic modulus of the adhesive sheet

I ₁ : the second moment of the area of the front panel

I ₂ : the second moment of the area of the adhesive sheet

h:a1+a2

σ: internal stress

According to the results of the test conducted by the inventors of the present invention, it is confirmed that the internal stress (σ) obtained by the above formulas (1) and (2) is 0.47 MPa or less in the laminate, and the high temperature can be effectively suppressed. Warpage in a high-humidity environment.

From this point of view, the internal stress (σ) in the laminated body is preferably 0.47 MPa or less, more preferably 0.46 MPa or less, still more preferably 0.45 MPa or less. Further, it is preferably 0.40 MPa or less, more preferably 0.30 MPa or less.

The above internal stress (σ) in the laminated body can be mainly composed of the thickness of the A layer, (layer A) The ratio of the thickness (A) to the total thickness (T) of the (A) layer and the (B) layer ((A)/(T)), the material of the A layer and the B layer, the thickness of the adhesive sheet, and the material, etc. Make adjustments.

Further, in the following embodiments, as a method of evaluating warpage in a high-temperature and high-humidity environment, an environment having a temperature of 85 ° C and a humidity of 85% RH is used as a high-temperature and high-humidity environment, but other environmental conditions such as temperature 60 may be employed. Environmental conditions such as °C, humidity 90% RH, or temperature 70 ° C, humidity 90% RH are used as a high temperature and high humidity environment.

<Use of this laminate>

As described above, the laminate is excellent in shape stability in a high-temperature and high-humidity environment, and can also improve transparency, impact resistance, surface hardness, and the like. Therefore, the laminate can be preferably used for various purposes, for example, it can be bonded to a substrate or the like and used as various substrate materials or protective materials. Other than various substrate materials or protective materials which are constituent materials of image display devices such as mobile phone terminals, smart phones, portable electronic game devices, portable information terminals, tablet devices, mobile personal computers, and wearable terminals. It can also be preferably used as various substrate materials or protective materials for constituent materials of a display type display device such as a liquid crystal television, a liquid crystal display, a desktop personal computer, a car navigation, and an automobile instrument.

Further, the laminated body can be imparted with a shape by various processing methods. For example, in addition to the method of heating and pressurizing using a mold, a vacuum forming method, a vacuum forming method, a roll forming method, or the like can be exemplified as a molding method. By imparting a shape to the laminated body, it can be used for an image display device having a curved surface or various flexible machines.

<Description of words, etc.>

Generally, the term "sheet" refers to a product which is thin in definition in JIS and whose thickness and length are small and flat compared with the width. Generally, the term "film" means that the thickness is extremely small compared with the length and the width. A thinner and flat article whose maximum thickness is arbitrarily defined is usually a supplier in the form of a reel (Japanese Industrial Standard JISK6900). However, the boundary between the sheet and the film is not clear, and in the present invention, it is not necessary to distinguish between the two words, therefore, the present invention In the case of "film", "sheet" is included, and even in the case of "sheet", "film" is included.

Further, when it is expressed as a "panel" as in an image display panel or a protective panel, it includes a plate body, a sheet, a film, or the like.

In the present specification, when it is described as "X~Y" (X, Y is an arbitrary number), unless otherwise specified, the meaning of "X or more and Y or less" is included, and "better" is included. Greater than X" or "preferably less than Y".

In addition, when it is described as "X or more" (X is an arbitrary number), unless otherwise specified, the meaning of "preferably greater than X" is included, and it is described as "Y or less" (Y is an arbitrary number) In the case of "), unless otherwise specified, the meaning of "preferably less than Y" is included.

[Examples]

Hereinafter, the description will be made in more detail by way of examples. However, the invention is not limited to the embodiments described below.

In addition, various measured values and evaluations shown in this specification are performed as follows.

(1) Thickness

The measurement was performed using a commercially available thickness measuring instrument (manufactured by MITUTOYO).

(2) Elastic modulus (E ₁ , E ₂ )

For the elastic modulus (E1) of the front panel, the dynamic viscoelasticity measuring device "DVA-200" manufactured by IT Meter and Control was used for the film by the dynamic viscoelasticity measurement method described in the JIS K-7198A method. The transverse direction (TD) was measured at a temperature rise rate of 1 ° C/min from -100 ° C to 200 ° C under conditions of a vibration frequency of 10 Hz and a strain of 0.1%. From the obtained data, a storage elastic modulus at a temperature of 20 ° C was obtained. The number (E') is used as the E _{1 for} the storage elastic modulus (E').

The elastic modulus (E ₂ ) of the adhesive sheet was measured and stretched at a test speed of 300 mm/min along the longitudinal direction of the adhesive sheet cut by the tensile tester.

(3) Warpage evaluation of the front panel alone by wet heat exposure test

The resin laminate (front panel) obtained in the examples and the comparative examples was cut into a size of 10 cm × 10 cm, and placed in a constant temperature and humidity chamber set to a temperature of 85 ° C and a humidity of 85% RH for 120 hours, and then set to The amount of warpage of the four corners was evaluated immediately after standing for 4 hours in a constant temperature and humidity chamber having an environment of a temperature of 23 ° C and a humidity of 50% RH.

In the amount of warpage, the convex surface of the test piece, that is, the resin laminate (front panel) was placed on a quartz pressure plate, and the height of the ridge of the four-corner self-pressing disk was visually measured using a height gauge to calculate the warpage amount δ of the four corners ( The average of mm).

(4) Calculation of internal stress

The front panel obtained in the examples and the comparative examples was cut into a size of 10 cm × 10 cm, and was calculated in a constant temperature and humidity chamber set to a temperature of 85 ° C and a humidity of 85% RH using the following formulas (1) and (2). Internal stress generated when exposed for 120 hours.

δ: In the front panel warp shape when the front panel is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, the front panel is left horizontally in a downwardly convex shape. Height of self-standing surface

L: sample length (10cm)

θ: in the front panel warp shape when the front panel is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, the front panel is horizontally placed in a downwardly convex shape from the front panel The angle between the center of curvature of the warped shape falling to the ground point of the front panel and the line connecting the center of curvature of the warped shape of the front panel to the end of the front panel

ρ ₁ : Curvature radius of the front panel warp shape when the front panel is exposed to an environment of temperature 85 ° C and humidity 85% RH for 120 hours.

a ₁ : thickness of the front panel

a ₂ : thickness of the adhesive sheet

b: sample width (10cm)

E ₁ : the modulus of elasticity of the front panel

E ₂ : elastic modulus of the adhesive sheet

I ₁ : the second moment of the area of the front panel

I ₂ : the second moment of the area of the adhesive sheet

h:a ₁ +a ₂

σ: internal stress

Here, the mode of the internal stress calculation model is shown in Fig. 1.

As a calculation process, first, the amount of warpage (δ) actually measured by the wet heat exposure test of the front panel alone is substituted into the formula (1), and the front panel is calculated only at a temperature of 85 ° C and a humidity of 85% RH. The radius of curvature (ρ ₁ ) of the front panel warp shape when exposed to an environment of 120 hours.

Then, the second moments (I _{1 and} I ₂ ) of the area of the front panel and the adhesive are calculated according to the following formulas (3) and (4). Then, the calculated ρ ₁ and other physical property values are substituted into the formula (2), and the internal stress (σ) is calculated.

(5) Damp heat exposure test of front panel/adhesive sheet/glass laminate

The laminate of the front panel/adhesive sheet/glass obtained in the examples and the comparative examples was It was set to a constant temperature and humidity chamber with a temperature of 85 ° C and a humidity of 85% RH for 120 hours, and then placed in a constant temperature and humidity chamber set to a temperature of 23 ° C and a humidity of 50% RH for 4 hours, and immediately confirmed by visual inspection. The appearance of the film.

At this time, if the amount of warpage caused by the wet heat exposure of the front panel is large, peeling occurs at the interface between the front panel and the adhesive sheet, and the appearance of the bubbles (air) at the peeling place may cause poor appearance. The size of the defective portion was evaluated by visual observation in accordance with the following criteria.

○ (better): the area ratio of the defective part is less than 10%

× (poor): The area ratio of the defective part is 10% or more

<Examples, Comparative Examples>

The main raw materials and materials used in the examples and comparative examples will be described.

(thermoplastic resin (a1-1))

Acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., trade name: ACRYPET VH001, density: 1.19 g/cm ³ , methyl methacrylate/methyl acrylate = 99/1 mass%, stereoregularity (ternary component ratio) ): mm (9.2 mol%), mr (41.8 mol%), rr (49.0 mol%), Tg: 111 ° C, MFR (Melt Flow Rate) (temperature: 230 ° C, load: 37.3N): 2.0g/10min)

(thermoplastic resin (a2-1))

Copolymer (Electrical Chemical Industry Co., Ltd., trade name: RESISFY R-100, density: 1.14 g/cm ³ , styrene / methyl methacrylate / maleic anhydride = 75 / 15/10 mass %, Tg: 127 ° C, MFR (temperature: 230 ° C, load: 37.3 N): 4.2 g/10 min)

(thermoplastic resin (a3-1))

The molar ratio of the monomer unit derived from isosorbide as a dihydroxy compound to the monomer unit derived from tricyclodecane dimethanol obtained by the method of JP-A-2008-024919 is an isosorbent Ester/tricyclodecane dimethanol = 70/30 mol% of polycarbonate copolymer (density: 1.36 g/cm ³ , Tg: 128 ° C, MFR (temperature: 230 ° C, load: 37.3 N): 9.6 g /10min)

(Polycarbonate resin (b1-1))

(Manufactured by Sumika Styron Polycarbonate, trade name: CALIBRE 301-15, density: 1.20 g/cm ³ , Tg: 149 ° C, MFR (temperature: 300 ° C, load: 11.8 N): 15.0 g/10 min)

(curable resin composition (c))

(c-1) (manufactured by MOMENTIVE, trade name "UVHC7800G")

(c-2) (manufactured by MOMENTIVE, trade name "XRC39-6210")

(adhesive sheet)

As the adhesive sheet, an adhesive resin composition containing an acrylate copolymer, a crosslinking agent, and a photopolymerization initiator is sandwiched between two peeled polyethylene terephthalate films to form a thickness. The modulus of elasticity (E ₂ ) formed by a sheet shape of 150 μm is 0.30 MPa and Tg: -10 ° C.

(glass plate)

As the glass plate, commercially available soda lime glass (width: 100 mm × length: 100 mm × thickness: 0.5 mm) was used.

<Example 1>

Each of the resin composition obtained by mixing 60 parts by mass of the acrylic resin (a1-1) and 40 parts by mass of the copolymer acrylic resin (a2-1) and 100 parts by mass of the polycarbonate resin (b1-1) The mixture is supplied to an extruder having a different exhaust function and a filtering function, and is melt-kneaded at a resin temperature of 240 to 265 ° C, and is used as a laminate of (A layer) / (B layer) in the feed module. After the T-die at 260 ° C was co-extruded, the first cooling roll set to 100 ° C, the second cooling roll set to 110 ° C, and the third cooling roll set to 150 ° C were sequentially cooled. The total thickness is 0.675 mm, and the thickness of each layer is (A layer) / (B layer) = 0.075 mm / 0.600 mm before the panel.

Then, a curable resin composition (cf) containing 60 parts by mass of the curable resin composition (c-1) and 40 parts by mass of the curable resin composition (c-2) is applied to the above by using a bar coater. The surface of the acrylic resin layer (layer A) of the front panel was dried at 90 ° C for 1 minute in this state, and then exposed to ultraviolet rays at an exposure amount of 700 mJ/cm ^{2 to} cure the curable resin composition (c) to form a surface. Hard coating (Cf).

Then, a curable resin composition (cb) containing 60 parts by mass of the curable resin composition (c-2) and 40 parts by mass of the curable resin composition (c-3) is applied to the above by using a bar coater. The surface of the polycarbonate resin layer (layer B) of the resin laminate was dried at 90 ° C for 1 minute in this state, and then exposed to ultraviolet rays at an exposure amount of 700 mJ/cm ² to obtain a curable resin composition (c). The hard coat layer (Cb) is hardened to form a front panel.

Then, the adhesive surface which peeled off the peeling film of one of the adhesive sheets was superposed on the surface of the hard-coat layer (Cb) of the said front panel, and was bonded by the hand-pressure roll. Then, the remaining release film was peeled off, and the soda lime glass (thickness: 0.5 mm) was superposed on the exposed adhesive surface, and pressure-bonded under reduced pressure (absolute pressure: 5 kPa), and then autoclaved (50 ° C, 0.2). MPa and 20 minutes) were bonded together to produce a laminate. Further, the laminated body was subjected to ultraviolet irradiation with a soda lime glass by a high-pressure mercury lamp at a wavelength of 2,000 nm to 2000 mJ/cm ^{2 to} cure the adhesive sheet, thereby producing the above-mentioned front panel/adhesive sheet/glass laminate.

<Examples 2 and 3>

As shown in Table 1, the front panel and the front panel/adhesive sheet were produced in the same manner as in Example 1 except that the thickness ratio and the total thickness of the layers of the A layer and the B layer of the front panel were changed in the first embodiment. Material/glass laminate.

<Example 4>

100 parts by mass of the thermoplastic resin (a3-1) and the polycarbonate resin (b1-1) parts by mass are supplied to an extruder having a difference in exhaust function and filtration function, and melted at a resin temperature of 240 to 265 ° C. Kneading, using a T-die having a multi-manifold to form a two-layered layer of (Af layer) / (B layer) / (Ab layer) by a T-die at 240 ° C Then, the first cooling roller set to 100 ° C and the second cooling roller set to 110 ° C were sequentially passed. And cooling the third cooling roll set to 120 ° C to obtain a total thickness of 0.675 mm, the thickness of each layer is (Af layer) / (B layer) / (Ab layer) = 0.075 mm / 0.525 mm / 0.075 mm before the panel, Thereafter, a hard coat layer was applied in the same manner as in Example 1 to prepare a front panel/adhesive sheet/glass laminate.

<Example 5>

100 parts by mass of the thermoplastic resin (a3-1) and the polycarbonate resin (b1-1) parts by mass are supplied to an extruder having a difference in exhaust function and filtration function, and melted at a resin temperature of 240 to 265 ° C. Kneading, using a T-die having a multi-manifold to form a two-layered layer of (Af layer) / (B layer) / (Ab layer) by a T-die at 240 ° C Thereafter, the first cooling roll set to 100 ° C, the second cooling roll set to 110 ° C, and the third cooling roll set to 120 ° C were sequentially cooled to obtain a total thickness of 0.275 mm, and the thickness of each layer was (Af). Layer)/(B layer)/(Ab layer)=0.075 mm/0.125 mm/0.075 mm front panel, after which a hard coat layer was applied in the same manner as in Example 1 to prepare a front panel/adhesive sheet/glass The fit of the body.

<Comparative Examples 1 to 4>

As shown in Table 1, the front panel was obtained in the same manner as in Example 1 except that the thickness ratio and the total thickness of the A layer and the B layer of the front panel were changed in the first embodiment, and thereafter, the front panel was produced/ Adhesive sheet/glass laminate.

<Comparative Examples 5 and 6>

As shown in Table 1, the thickness of the hard coat layer (Cb) was changed in Example 1, except that the front panel was obtained in the same manner as in Example 1, and thereafter, the front panel/adhesive sheet/glass was produced. Fit the body.

<Comparative Examples 7, 8>

As shown in Table 1, the front panel was obtained in the same manner as in Example 1 except that the temperature of the third cooling roll was changed during the co-extrusion molding of the front panel in Example 1, and thereafter, the front panel was produced/ Adhesive sheet/glass laminate.

As shown in Tables 1 and 2, in the configurations of Examples 1 to 5, peeling was not performed in the wet heat environment test, and in contrast, in Comparative Examples 1 to 8, peeling occurred.

It is considered that there is a correlation between the peeling behavior when the wet heat environment test is performed and the internal stress σ calculated by the formula (1) and the formula (2), and it can be confirmed that when the internal stress σ is not more than a certain value, the wet heat environment test can be suppressed. Stripping. The reason for this is considered to be that if the internal stress caused by the warpage generated when the front panel is subjected to the wet heat exposure test is reduced to a certain level or less, the adhesion to the adhesive sheet prevails, and peeling can be suppressed. It was confirmed that the internal stress: 0.47 MPa was approximately the threshold value at which peeling occurred.

Examples of the factors affecting the front panel of the internal stress include the elastic modulus, the thickness, and the amount of warpage according to the formulas (1) and (2). Among them, the internal stress can be mainly reduced by making the thickness thin or making the amount of warpage small. That is, when it is easy to assume that any one is large, it is also possible to reduce the internal stress by adjusting another parameter to an appropriate range, thereby suppressing peeling.

Examples of the method for reducing the amount of warpage include adjusting the layer constitution of the A layer and the B layer, the thickness ratio of the A layer and the B layer, the thickness ratio of the front and back coating layers, and the processing conditions such as the roll temperature conditions at the time of production. The method.

Among them, it is effective to form a layer of the A layer and the B layer into two layers of the A layer/B layer/A layer. By setting it as a symmetrical structure, the difference in the expansion and contraction behavior of the A layer and the B layer can be eliminated on the front and back sides, so that the reduction in warpage is effective.

It can be confirmed from the examples 4 and 5 that the front panel symmetrical structure can be used as the front panel by using two types of three-layered front and back symmetrical constitutions, and the two panels of the two layers of the A layer and the B layer can be used. And internal stress suppression is small.

As another method of reducing the amount of warpage, the thickness (A) of the first layer (A layer) of the two layers of the A layer/B layer is made larger than the total thickness of the (A) layer and the (B) layer (T). The method of decreasing the ratio ((A)/(T)) is effective. Since the warping is caused by the difference in the expansion and contraction behavior of the two layers, for example, if the layer A is made extremely thin and the thickness ratio becomes uneven in a manner close to the single layer of the layer B, the layer A is The influence is hard to appear, so warping behavior can be suppressed.

As another method of reducing the amount of warpage, it is effective to make the composition of the hard coat layer (C layer) on the front and back sides close to the front and back objects. When the hard coat layer (C layer) is exposed to the damp heat test, the hard coat layer itself shrinks due to the progress of the hardening shrinkage and becomes a cause of warpage. Therefore, in order to suppress warpage, it is preferable to obtain a hard coat layer of the front side. The composition is the balance of material and thickness.

When the material composition of the hard coat layer is the same on the front side and the back side, it is preferable to make the thickness of the two layers close to each other. When the material composition of the hard coat layer is different between the front and back sides, it is preferable to consider each hard coat layer. The thickness is adjusted so as to obtain a balance between the front and the back in terms of the elastic modulus of the material and the amount of hardening shrinkage.

As another method of reducing the amount of warpage, a method of reducing the thermal strain during cooling by adjusting the film forming conditions at the time of co-extrusion is effective. For example, the thermal strain can be reduced by the annealing effect by increasing the temperature of the third cooling roll in a range that does not cause an appearance defect.

In Comparative Examples 1 to 8, since the internal stress was large, peeling occurred.

In Comparative Example 1, the total thickness was as thick as 1000 μm, and even when the amount of warpage was small, the influence of the thickness was large and the internal stress was large.

In Comparative Examples 2 to 4, since the thickness ratio of the A layer to the B layer was large, the amount of warpage of the front panel was large, and the internal stress was large.

In Comparative Examples 5 to 6, the thickness of the hard coat layer (Cf) on the back surface was thin, and the balance of the hard coat layer on the front and back sides could not be obtained. Therefore, the amount of warpage of the front panel was large, and the internal stress was large.

In Comparative Examples 7 to 8, the temperature of the third cooling roll did not sufficiently reach the high temperature, the thermal strain of the front panel was large, the amount of warpage was large, and the internal stress was large.

δ‧‧‧The height of the front end of the front panel from the static surface

L‧‧‧ sample length

ρ‧‧‧The radius of curvature of the front panel warped shape

θ‧‧‧An angle from the center of curvature of the warp shape of the front panel to the ground line of the front panel and the line connecting the center of curvature of the warped shape of the front panel to the end of the front panel

10‧‧‧ front panel

20‧‧‧Adhesive sheets

Claims (11)

A laminated body comprising a front panel and an adhesive sheet; and the front panel has a B layer mainly composed of a polycarbonate resin and a thermoplastic different from the polycarbonate resin The thermoplastic resin A layer mainly composed of a resin, the total thickness of the A layer is 10 μm to 250 μm, and the ratio of the thickness (A) of the A layer 1 layer to the total thickness (T) of the A layer and the B layer ((A) ) / (T)) is 0.05 to 0.40, and the laminate of the front panel and the adhesive sheet is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH by the following formulas (1) and (2). The internal stress (σ) of the front panel and the adhesive sheet at 120 hours is 0.47 MPa or less: δ: In the front panel warp shape when the front panel is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, the front panel is left horizontally in a downwardly convex shape. Height of the ridge of the self-standing surface L: Sample length (10 cm) θ: In the front panel warp shape when the front panel is exposed to an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, the front panel is When the downwardly convex shape is horizontally rested, the center of curvature from the warping shape of the front panel falls to the perpendicular line of the grounding point of the front panel and the line connecting the center of curvature of the warping shape of the front panel and the end point of the front panel Angle ρ ₁ : Curvature radius of the front panel warp shape when the front panel is exposed to an environment of temperature 85 ° C and humidity 85% RH for 120 hours a ₁ : thickness of the front panel a ₂ : adhesive sheet Thickness b: sample width (10 cm) E ₁ : elastic modulus of the front panel E ₂ : elastic modulus of the adhesive sheet I ₁ : area of the front panel second moment I ₂ : area of the adhesive sheet second moment h: a ₁ + a ₂ σ: internal stress. The laminate according to claim 1, wherein the front panel is allowed to stand in an environment of a temperature of 85 ° C and a humidity of 85% RH for 120 hours, and then placed at a temperature of 23 ° C and a humidity of 50% RH for 4 hours. The average amount of warpage (δ) is 1.5 mm or less. The laminate according to claim 1 or 2, wherein the thermoplastic resin which is a main component resin of the A layer is an acrylic resin. The laminate according to any one of claims 1 to 3, wherein the thermoplastic resin as the main component resin of the A layer comprises a methyl methacrylate monomer and a methacrylic acid monomer, an acrylic monomer, and a maleic anhydride monomer. An acrylic resin (a1) of a copolymer of any one or more of an aromatic vinyl monomer and an acrylonitrile monomer. The laminate according to any one of claims 1 to 3, wherein the thermoplastic resin as the main component resin of the layer A contains: an acrylic resin (a1) comprising a methyl methacrylate monomer and a methacrylic monomer, a copolymer of any one or more of an acrylic monomer, a maleic anhydride monomer, an aromatic vinyl monomer, and an acrylonitrile monomer; and a copolymer (a2) having an aromatic vinyl monomer unit, (methyl An acrylate monomer unit and a maleic anhydride monomer. The laminate according to claim 1 or 2, wherein the thermoplastic resin as a main component of the layer A is a polycarbonate resin containing a structural unit derived from a dihydroxy compound represented by the following (Chemical Formula 1) in a part of the structure (a3) ): The laminate according to any one of claims 1 to 6, wherein the polycarbonate resin as the main component resin of the B layer contains the polycarbonate resin (b1) and contains an aromatic (meth) acrylate monomer. 5 to 80% by mass of an acrylic copolymer (b2) having a methyl methacrylate monomer unit of 95 to 20% by mass. The laminate according to any one of claims 1 to 7, wherein the adhesive sheet has an elastic modulus (E ₂ ) of 0.001 to 30 MPa. The laminate according to any one of claims 1 to 8, wherein the total thickness of the front panel is 0.7 mm or less. The laminate according to any one of claims 1 to 9, wherein the front panel is provided with the same main resin as the main component of the adhesive sheet, in addition to the A layer and the B layer, on the side of the adhesive sheet. Resin as a hard coating of the main component. An image display device comprising the laminate according to any one of claims 1 to 10.