TWI723985B - Layered body - Google Patents

Abstract

The present invention relates to a laminate including a polycarbonate resin layer, a front panel of a thermoplastic resin different from the polycarbonate resin, and an adhesive sheet, and provides an excellent shape stability in a high temperature and high humidity environment Novel laminated body.

The present invention proposes a laminated body characterized in that it includes a front panel and an adhesive sheet, and the front panel includes a layer B containing polycarbonate resin as the main component resin, and the polycarbonate resin A layer of thermoplastic resin with different resin as the main component, the total thickness of the A layer is 10μm~250μm, the ratio of the thickness (A) of the above layer A to the total thickness (T) of the above layer A and the above layer B ( (A)/(T)) is 0.05~0.40. When the laminate of the front panel and the adhesive sheet is exposed for 120 hours in an environment with a temperature of 85°C and a humidity of 85%RH, the inside of the front panel and the adhesive sheet The stress (σ) is 0.47 MPa or less.

Description

Layered body

The present invention relates to a laminated body. In detail, regarding a material that can be used as a substrate material or a protective material, for example, it can be preferably used as a surface protection panel of an image display device, or a housing material for mobile phones, smart phones, tablet devices, wearable terminals, etc. The multi-layered body.

Since the beginning, glass has been mainly used as the housing material of image display devices. However, glass is easily broken by impact and is heavy. Therefore, research has been conducted on the use of resin materials instead of glass.

For this kind of resin material as a glass substitute material, impact resistance, surface hardness, and shape stability under high temperature and high humidity environment are mainly required.

Polycarbonate resin plates have transparency and are excellent in impact resistance or heat resistance, so they are used for soundproof partitions or carports, signage, reflective materials, lighting fixtures, and the like. However, due to the low surface hardness, it has the disadvantage of being easily damaged.

In order to improve this disadvantage, for example, Patent Document 1 discloses a resin laminate obtained by subjecting a laminate formed by co-extruding a polycarbonate resin and an acrylic resin to a hard coating process.

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

Similarly, as a method of suppressing the warpage of the polycarbonate resin sheet, Patent Document 3 discloses a laminated polycarbonate resin that defines the glass transition temperature difference of each layer A resin laminate with poor water absorption.

[Prior Technical Literature] [Patent Literature]

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

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

[Patent Document 3] WO2014/061817

As described above, the front panel is provided with a polycarbonate resin layer and a layer containing a thermoplastic resin different from the polycarbonate resin, for example, by laminating an adhesive sheet on a substrate, etc., and is used as a surface protection for an image display device. Panel or housing material. However, in the front panel of this configuration, the thermal expansion coefficient or hygroscopicity of the polycarbonate resin is different from that of the thermoplastic resin that is different from the polycarbonate resin. Therefore, there are problems as follows: , A resin layer will absorb moisture and cause dimensional changes, etc., and it is difficult to maintain the shape stability of the front panel.

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

The present invention proposes a laminate characterized in that it includes a front panel and an adhesive sheet, and the front panel includes a layer B containing polycarbonate resin as the main component, and is combined with the polycarbonate resin A layer of thermoplastic resin with a different thermoplastic resin as the main component, the total thickness of the A layer is 10~250μm, the ratio of the thickness (A) of the above A layer to the total thickness (T) of the above A layer and the above B layer ((A)/(T)) is 0.05~0.40, using the following formula (1) and formula (2) to obtain the above-mentioned laminated body exposed to a temperature of 85 ℃, humidity 85% RH environment for 120 hours In this case, the internal stress (σ) of the front panel and the adhesive sheet is 0.47 Below MPa.

In the laminate proposed by the present invention, in the structure of the front panel, the total thickness of the A layer of the thermoplastic resin mainly composed of a thermoplastic resin different from the polycarbonate resin, and the thickness of the layer A relative to the thickness of the A layer are specified. The ratio ((A)/(T)) of the total layer thickness of the layer and the above-mentioned B layer, and the internal stress (σ) is specified in a specific range, which can exert excellent shape stability in a high temperature and high humidity environment performance.

Therefore, the laminate proposed by the present invention can be bonded to a base material, for example, and is preferably used as various substrate materials, protective materials, and the like. In addition to various substrate materials or protective materials that are used as constituent materials of portable display devices such as mobile phone terminals, smart phones, portable electronic game equipment, portable information terminals, tablet devices, mobile personal computers, wearable terminals, etc. It can also be preferably used as various substrate materials or protective materials as constituent materials of set-up display devices such as liquid crystal televisions, liquid crystal displays, desktop personal computers, car navigation, car meters, etc.

δ‧‧‧The bulge height of the end surface of the front panel from the resting surface

L‧‧‧Sample length

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

θ‧‧‧From the center of curvature of the warped shape of the front panel to the grounding point of the front panel The angle between the vertical line and the straight line connecting the center of curvature of the front panel's warped shape and the end point of the front panel

10‧‧‧Front Panel

20‧‧‧Adhesive sheet

Figure 1 is a schematic diagram of the model used to calculate the internal stress.

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

In this specification, the "main component" of each layer refers to the resin component with the highest proportion (mass%) in the resin composition forming each layer. The specific content is not specified, but as a standard, it accounts for the amount of the resin composition that forms each layer. 50% by mass or more of the resin contained in the resin composition, especially 80% by mass or more, and more particularly 90% by mass or more (including 100% by mass) resin. In addition, when the main component is more than two kinds , The total amount of them is equivalent to the above content.

In addition, the so-called ""principal component" of the polymer and its derivatives" means the monomer with the highest proportion among the monomer units constituting the polymer and its derivatives.

<This multilayer body>

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

<Front Panel>

The front panel of the laminated body only needs to have a layer B containing a polycarbonate resin as a main component and a layer A thermoplastic resin containing a thermoplastic resin different from the polycarbonate resin as a main component. As an example, a layer A having an acrylic resin as a main component resin and a layer B having a polycarbonate resin as a main component resin can be cited.

In addition, for example, a front panel in which the A layer is formed on one side or both sides of the B layer is exemplified.

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

<Level A>

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

Here, the term "different" means that the types or composition ratios of the monomers constituting the polymer are different.

The thermoplastic resin that is the main component of the A layer is not particularly limited as long as it is different from the polycarbonate resin that is the main component of the B layer described below. For example, it can be exemplified by polyethylene terephthalate, poly(ethylene terephthalate) and polycarbonate resin. Aromatic polyesters such as ethylene naphthalate, polytrimethylene terephthalate, polybutylene terephthalate, poly-1,4-cyclohexane dimethyl terephthalate, and polylactic acid series Polyester resins represented by aliphatic polyesters such as polymers, polyolefin resins such as polyethylene, polypropylene, cycloolefin resins, polycarbonate resins, acrylic resins, polystyrene resins, and polyamide resins Resin, polyether resin, polyurethane resin, polyphenylene sulfide resin, polyester amide resin, polyether ester resin, vinyl chloride resin, acrylonitrile -Styrenic copolymer, acrylonitrile-butadiene-styrene copolymer, modified polyphenylene ether resin, polyarylate resin, polysulfide resin, polyetherimide resin, polyamide resin Amine resins, polyimide resins and copolymers with these as main components, or mixtures of these resins, etc. These may be one kind or a mixture of two or more kinds.

In addition, as the above-mentioned polycarbonate resin used as the main component of the A layer, it is sufficient if it is different from the polycarbonate resin used as the main component of the B layer described below. For example, aliphatic polycarbonate or grease may be mentioned. Cyclic polycarbonate, aromatic polycarbonate containing bisphenol C, etc.

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

<Preferable specific structure example of A layer>

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

In addition, as another preferable example of the A layer, a layer containing a polycarbonate resin (a3) derived from a dihydroxy compound-derived structural unit in a part of the structure as a main component resin can also be cited.

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

(Acrylic resin (a1))

The acrylic resin (a1) is a (co)polymer and its derivatives obtained by polymerizing (meth)acrylate monomer units as the main component.

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

基酯、(甲基)丙烯酸降

基酯、(甲基)丙烯酸二環戊烯酯、(甲基)丙烯酸二環戊酯、(甲基)丙烯酸二環戊烯基氧基乙酯、(甲基)丙烯酸四氫呋喃甲酯、丙烯醯基(甲基)丙烯酸酯、(甲基)丙烯酸2-羥基乙酯、琥珀酸2-(甲基)丙烯醯氧基乙酯、馬來酸2-(甲基)丙烯醯氧基乙酯、鄰苯二甲酸2-(甲基)丙烯醯氧基乙酯、六氫鄰苯二甲酸2-(甲基)丙烯醯氧基乙酯、(甲基)丙烯酸五甲基哌啶酯、(甲基)丙烯酸四甲基哌啶酯、(甲基)丙烯酸二甲胺基乙酯、(甲基)丙烯酸二乙胺基乙酯等。該等可僅單獨使用1種或組合2種以上而使用。又，作為可與該等丙烯酸系單體單元聚合之其他單體單元，例如可列舉烯烴系單體單元、乙烯系單體單元等。 Examples of the (meth)acrylate monomer unit include methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic acid. Isobutyl ester, tertiary 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, (meth)acrylate Base) cyclohexyl acrylate, (meth) acrylate iso

Base ester, (meth)acrylic acid

Base ester, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, methyl tetrahydrofuran (meth)acrylate, acrylic acid Base (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acryloxyethyl succinate, 2-(meth)acryloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidine (meth)acrylate, (meth) Yl)tetramethylpiperidine acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like. These can be used individually by 1 type or in combination of 2 or more types. In addition, examples of other monomer units that can be polymerized with these acrylic monomer units include olefin-based monomer units and vinyl-based monomer units.

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

There is no particular restriction on the stereoregularity of the acrylic resin (a1). 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, so it is preferable. From this viewpoint, the three-dimensional structure having the highest molar ratio of rr among the ternary component ratios of mm, mr, and rr can be preferably used. The ternary component ratio can be measured by a known method using a nuclear magnetic resonance measuring device (1H-NMR).

(Copolymer (a2))

As described above, the A layer is preferably a layer containing the above-mentioned acrylic resin (a1) and the copolymer (a2). Among them, it is preferable to mix the acrylic resin (a1) and the copolymer (a2) to form A Floor.

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

Examples of the above-mentioned "aromatic vinyl monomer unit" include those derived from styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, and ethylbenzene. Units of styrene monomers such as ethylene, p-tert-butylstyrene, α-methylstyrene, and α-methyl-p-methylstyrene. These aromatic vinyl monomer units can be used individually by 1 type or in combination of 2 or more types.

Among them, styrene units or α-methylstyrene units are preferred. The styrene monomer unit is preferred because it is easy to obtain industrially and has excellent economic efficiency, and the α-methylstyrene monomer unit is preferred because it can increase the glass transition temperature.

基酯等各甲基丙烯酸酯單體、及丙烯酸甲酯、丙烯酸乙酯、丙烯酸正丁酯、丙烯酸2-甲基己酯、丙烯酸2-乙基己酯、丙烯酸癸酯等丙烯酸酯單體之單元。該等(甲基)丙烯酸酯單體單元可僅單獨使用1種或組合2種以上而使用。 Examples of the above-mentioned "(meth)acrylate monomer unit" include those derived from methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid. Dicyclopentyl ester, methacrylic acid iso

Of methacrylate monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, decyl acrylate and other acrylate monomers unit. These (meth)acrylate monomer units can be used individually by 1 type or in combination of 2 or more types.

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

Examples of the "unsaturated dicarboxylic anhydride monomer unit" include units derived from each anhydride monomer such as maleic anhydride, itaconic anhydride, citraconic anhydride, and aconitic anhydride. These unsaturated dicarboxylic anhydride monomer units can be used individually by 1 type or in combination of 2 or more types.

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

The constituent units of the above-mentioned copolymer (a2) are preferably 45 to 85% by mass of aromatic vinyl monomer units, 4 to 45% by mass of (meth)acrylate monomer units, and unsaturated dicarboxylic anhydride monomers. Unit 8-20% by mass, more preferably 55-85% by mass of aromatic vinyl monomer units, 5-30% by mass of (meth)acrylate monomer units, and 10-18% by mass of unsaturated dicarboxylic anhydride monomer units % Range.

Furthermore, the constituent units of the copolymer (a2) can be qualitatively and quantitatively analyzed by a well-known method, such as a nuclear magnetic resonance (NMR) measuring device and other equipment analysis devices.

If the aromatic vinyl monomer units in all the constituent units of the copolymer (a2) account for 45% by mass or more, especially 55% by mass or more, the thermal stability is improved, and good performance can be obtained when mixed with the acrylic resin (a1) The appearance can further reduce the water absorption, so it is better.

In addition, if the (meth)acrylate monomer units in all the structural units of the copolymer (a2) account for 4% by mass or more, especially 5% by mass or more, the compatibility with the acrylic resin (a1) is improved and transparency The sex becomes better, so it is better.

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

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

In addition, if the ratio of (meth)acrylate monomer units in all the constituent units of the copolymer (a2) is 45% by mass or less, especially 30% by mass or less, compatibility with the acrylic resin (a1) can be ensured It is preferred because of its properties and can inhibit water absorption.

In addition, if the proportion of unsaturated dicarboxylic anhydride units in all the structural units of the copolymer (a2) is 20% by mass or less, especially 18% by mass or less, compatibility with the acrylic resin (a1) can be ensured, and It can improve thermal stability or inhibit water absorption, so it is preferred.

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

Examples of the "other copolymerizable units" include acrylonitrile monomers such as acrylonitrile and methacrylonitrile, vinyl carboxylic acid monomers such as acrylic acid and methacrylic acid, N-methylmaleimide, N-alkylmaleimide monomers such as N-ethylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide Units of various monomers such as N-aryl maleimide monomers such as amine, N-methylphenyl maleimide, and N-chlorophenyl maleimide. These copolymerizable units can be used individually by 1 type or in combination of 2 or more types.

The weight average molecular weight (Mw) of the copolymer (a2) measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 100,000 to 200,000. Here, if the weight average molecular weight (Mw) is in this range, the A layer obtained by mixing with the acrylic resin (a1) has excellent moldability, appearance, and the like, which is preferable. From this point of view, a more preferable range of the weight average molecular weight (Mw) is 110,000~180,000.

The method for producing the copolymer (a2) can be produced by a known polymerization method, and it is not particularly limited. For example, solution polymerization or bulk polymerization can be applied, and the polymerization process can also adopt batch or semi-batch, continuous, etc. as appropriate. In this laminate, in terms of fewer by-products, easy control of molecular weight adjustment and transparency, etc., a batch-type polymerization process under solution polymerization can be preferably used.

((a1)/(a2))

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

If the mixing ratio of the acrylic resin (a1) and the copolymer (a2) is within the above range, the interlayer adhesion to layer B is excellent, the surface hardness or transparency characteristic of acrylic resins can be maintained, and the heat resistance can be improved It is preferred because of its properties or inhibition of water absorption.

In addition, in order to reduce the internal stress generated in the high-temperature and high-humidity environment of the laminated body, (a1)/(a2)=70/30~40/60 is preferred, and 70/30~60/40 is more preferred.

(Polycarbonate resin (a3))

As described above, it is also preferable that the A layer has a polycarbonate resin (a3) having a specific structure as a main component. Thereby, high surface hardness can be imparted to the laminate.

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

As the dihydroxy compound represented by the above (Chemical Formula 1), for example, isosorbide, isomannide, and isoidide which are in the relationship of stereoisomers can be cited. These can be used individually or in combination of 2 or more types.

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

In the polycarbonate resin (a3) as the main component of the A layer, the content of the structural unit derived from the dihydroxy compound represented by (Chemical 1) is preferably 50 mol% or more, more preferably 60 mol% Above, it is preferably 90 mol% or less, and more preferably 80 mol% or less.

Since the polycarbonate resin (a3), which is the main component of the A layer, contains the structural unit derived from the dihydroxy compound represented by (Chemical 1) in the above range, the hardness of the polycarbonate resin (a3) is Taking the intermediate value between the aromatic polycarbonate resin and the acrylic resin, the press workability is significantly improved compared to the display front panel with the acrylic resin layer arranged on the surface layer.

More specifically, since the content of the structural unit is 90 mol% or less, it has excellent surface hardness and heat resistance, and can suppress impact resistance and interlayer adhesion with the following layer B Therefore, it is possible to prevent various defects such as a decrease in yield rate during press processing and damage during processing of products used as front panels for displays.

On the other hand, since the above-mentioned content ratio is 50 mol% or more, it is excellent in impact resistance or press workability, and can suppress a decrease in surface hardness or heat resistance. In addition, the laminated body can obtain sufficient surface hardness by arranging a hard coat on at least one side, and can be preferably used for any application of a front panel for a display and a transparent building material.

The polycarbonate resin (a3) may also have structural units other than the above structural units, for example, the structural units derived from aliphatic dihydroxy compounds described in International Publication No. 2004/111106, or International Publication No. 2007/ The structural unit derived from an alicyclic dihydroxy compound described in No. 148604.

Among the above-mentioned structural units derived from aliphatic dihydroxy compounds, it is preferable to have those derived from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. The structural unit of at least one dihydroxy compound in the group consisting of diols.

Among the structural units derived from the alicyclic dihydroxy compound, those containing a 5-membered ring structure or a 6-membered ring structure are preferred. The 6-membered ring structure can also be fixed into a chair or boat shape by covalent bonds. By including a structural unit derived from an alicyclic dihydroxy compound as a 5-membered ring structure or a 6-membered ring structure, the heat resistance of the obtained polycarbonate can be improved. The number of carbon atoms contained in the alicyclic dihydroxy compound is generally preferably 70 or less, more preferably 50 or less, and still more preferably 30 or less.

Examples of the alicyclic dihydroxy compound containing the above-mentioned 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 can be preferably exemplified.

Furthermore, from the viewpoint of easy industrial availability, it is preferable to select cyclohexane dimethanol, and among them, 1,4-cyclohexane dimethanol is preferable. On the other hand, when attaching importance to heat resistance or indirect adhesion to the layer of the following B layer, tricyclodecane dimethanol is preferably selected.

The polycarbonate resin (a3) used in the A layer can be produced by a generally used polymerization method, and can be any of a phosgene method or a transesterification method that reacts with a carbonic acid diester. Among them, it is preferable to make the dihydroxy compound represented by (Chemical 1) above, aliphatic and/or alicyclic hydroxy compound, and other dihydroxy compounds as necessary in a part of the structure in the presence of a polymerization catalyst A transesterification method in which a compound and a carbonic acid diester are reacted.

The transesterification method is a manufacturing method as follows: to a part of the structure represented by the above (Chemical 1) dihydroxy compound, aliphatic and/or alicyclic hydroxy compound, other dihydroxy compounds used as needed, and carbonic acid The diester adds an alkaline catalyst and an acidic substance that neutralizes the alkaline catalyst to perform a transesterification reaction.

Representative examples of carbonic acid diesters include diphenyl carbonate, xylene carbonate, bis(chlorophenyl) carbonate, m-tolyl carbonate, dinaphthyl carbonate, bis(biphenyl) carbonate, and diethyl carbonate. Ester, dimethyl carbonate, dibutyl carbonate and dicyclohexyl carbonate, etc. Among these, it is particularly preferable to use diphenyl carbonate.

The molecular weight of the polycarbonate resin (a3) can be expressed in terms of reduced viscosity, and the lower limit of the reduced viscosity is preferably 0.20 dl/g or more, more preferably 0.30 dL/g or more, and even more preferably 0.35 dL/g As described above, the upper limit of the reduced viscosity is preferably 1.20 dL/g or less, more preferably 1.00 dL/g or less, and still more preferably 0.80 dL/g or less.

If the specific viscosity of the polycarbonate resin is too low, the mechanical strength of the molded product may be low. If it is too large, the fluidity during molding may decrease, which may reduce productivity or moldability.

(Other ingredients)

The A layer may appropriately contain various additives, modifiers, etc. within a range that does not impair the effects of the present invention. Here, examples of additives include antioxidants, ultraviolet absorbers, light stabilizers, lubricants, flame retardants, colorants, and the like. Moreover, as a modifier, an impact resistance modifier, a compatibilizer, an antistatic agent, etc. are mentioned, for example.

<Level B>

The B layer is a layer having functions such as impact resistance or heat resistance among the functions of the laminate.

The layer B may use the polycarbonate resin (b1) alone as the main component resin, or the polycarbonate resin (b1) may be mixed with the following various modifiers (b2) and used as the main component resin.

(Polycarbonate resin (b1))

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

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

Furthermore, 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 the phosgene method, the transesterification method, and the pyridine method.

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

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

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

(Modifier (b2))

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

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 aromatic (meth)acrylate monomer units and 95 to 20% by mass of methyl methacrylate monomer units.

If 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-mentioned range, it can show a difference with the polycarbonate resin (b1) Compatibility or surface hardness improvement effect, so it is better.

From this viewpoint, 10 to 70% by mass of aromatic (meth)acrylate monomer units and 90 to 30% by mass of methyl methacrylate monomer units are more preferable, and aromatic (meth) acrylate monomer units are more preferable. 25-60% by mass of acrylate monomer units and 75-40% by mass of methyl methacrylate monomer units.

As said aromatic (meth)acrylate monomer unit, phenyl (meth)acrylate, benzyl (meth)acrylate, etc. are illustrated, for example. These can be used individually by 1 type or in combination of 2 or more types.

Among them, in terms of compatibility with the polycarbonate resin (b1), etc., phenyl methacrylate or benzyl methacrylate is preferred, and phenyl methacrylate is more preferred.

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

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

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

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

From this viewpoint, the range of the weight average molecular weight (Mw) of the acrylic resin (b2) is more preferably 10,000-28,000.

The mixing mass ratio of the polycarbonate resin (b1) and the acrylic resin (b2) is not particularly limited, but it is preferably (b1)/(b2)=99~65/1~35. If the mixing ratio of the two is within this range, the obtained B layer has excellent moldability, surface hardness improvement effect, appearance, and the like, which is preferable.

From this viewpoint, (b1)/(b2)=95/5~70/30 is more preferable.

(Preferable 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 higher the glass transition temperature of the polycarbonate-based resin, which is the main component resin of the B layer, the better. It is a homopolymer using polycarbonate resin (b1). On the other hand, when attaching importance to the surface hardness of the laminate, it is preferable to contain the polycarbonate resin (b1) and the modifier (b2).

(Other ingredients)

The layer B can be blended with the above various additives or other resins within a range that does not impair the effects of the invention.

Examples of the additives include antioxidants, ultraviolet absorbers, light stabilizers, lubricants, flame retardants, colorants, and anti-hydrolysis agents.

(Glass transition temperature of each layer)

From the viewpoint of suppressing internal stress generated in a high-temperature and high-humidity environment, the smaller the difference between the glass transition temperature of layer A and the glass transition temperature of layer B, the better, preferably 100~140℃, and more preferably 110 The temperature is higher than or equal to 140°C, and among these, 115°C or higher is more preferable, and 120°C or higher is particularly preferable among them.

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

In addition, if the absolute value of the difference between the glass transition temperature of the A layer and the glass transition temperature of the B layer is 30°C or less, the high-temperature and high-humidity ring with a temperature of 85°C and a humidity of 85%RH can be further suppressed The warpage of the front panel after the environmental test is better. From this point of view, the absolute value of the difference is preferably 30°C or less, particularly preferably 20°C or less, particularly preferably 10°C or less, and particularly preferably 5°C or less.

It is believed that the reason is that in a high temperature and high humidity environment, the softening temperature of the A layer will be lowered due to water absorption, and therefore, various strain relaxation phenomena are likely to occur. However, if the absolute value of the difference is within the above range, it will be in high temperature and high humidity. The dimensional change behavior of the two layers under the environment is similar, and as a result, the warpage is suppressed.

In addition, the said glass transition temperature is the value measured using the differential scanning calorimeter in accordance with JIS K7121 at a heating rate of 10 degreeC/min. However, other well-known machine analysis devices, such as dynamic viscoelastic devices, etc., can also be used to measure the glass transition temperature.

<Hard coat (C layer)>

The front panel may further have a hard coat layer (C layer) as the outermost layer on one side or both sides. However, the hard coat layer (layer C) may not be provided.

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 the C layer by irradiating energy rays such as electron beams, radiation, or ultraviolet rays, or curing the curable resin composition for forming the C layer by heating. .

Among them, from the viewpoint of molding time and productivity, it is preferable to form a hard coat layer (C layer) by curing the curable resin composition for forming the C layer by irradiating ultraviolet rays.

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

As a specific example of the above-mentioned curable resin C1, for example, an acrylate compound Compounds, acrylic urethane compounds, epoxy acrylate compounds, carboxyl modified epoxy acrylate compounds, polyester acrylate compounds, copolymerized acrylates, alicyclic epoxy resins, glycidyl ether epoxy resins, Vinyl ether compounds, oxetane compounds, etc. These curable resins can be used individually by 1 type or in combination of 2 or more types.

As the curable resin C1 that imparts more excellent surface hardness, polyfunctional acrylate compounds, polyfunctional acrylate urethane compounds, polyfunctional epoxy acrylate compounds, etc., radical polymerization-based curable compounds, or Alkoxysilane, alkylalkoxysilane, etc., a thermally polymerized curable compound, and further, may be an organic-inorganic composite curable resin composition in which the above-mentioned curable resin contains an inorganic component.

Examples of the curable resin composition for forming a C layer that imparts particularly excellent surface hardness include organic and inorganic hybrid curable resin compositions. As an organic-inorganic hybrid curable resin composition, the curable resin composition containing the said curable resin containing the inorganic component which has a reactive functional group is mentioned.

By using such an inorganic component with a reactive functional group, for example, the inorganic component is copolymerized and crosslinked with a radical polymerizable monomer, and the organic and inorganic composite system is formed by only the organic binder containing the inorganic component. Compared with the curable resin composition, it is difficult to produce curing shrinkage, and can exhibit a higher surface hardness, so it is preferable. Furthermore, from the viewpoint of reducing curing shrinkage, a more preferable example is an organic-inorganic hybrid curable resin composition containing ultraviolet-reactive colloidal silica as an inorganic component having a reactive functional group.

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

From this viewpoint, it is preferable to set the concentration of the inorganic component contained in the hard coat layer (C layer), particularly the inorganic component having a reactive functional group, to 10 to 65% by mass. If the concentration is 10% by mass or more, the effect of imparting excellent surface hardness to the hard coat layer (C layer) can be obtained Fruit, therefore better. On the other hand, if the concentration is 65% by mass or less, the hard coat layer (C layer) can be most densely filled with inorganic components, especially inorganic components with reactive functional groups, and can effectively impart excellent surface hardness , Therefore better.

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

Furthermore, from the viewpoint of improving the adhesion with the following adhesive sheets 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 acrylic resin, it is preferable that the main component resin of the hard coat layer (C layer) is also acrylic resin.

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

類、苯偶醯二甲基縮酮類、α羥基烷基苯酮類、α-羥基苯乙酮類、羥基酮類、胺基烷基苯酮類、醯基氧化膦類等。其中，α-羥基烷基苯酮類於硬化時難以引起黃變，可獲得透明之硬化物，故而較佳。又，胺基烷基苯酮類具備非常高之反應性，可獲得優異之硬度之硬化物，故而較佳。上述光聚合起始劑可僅單獨使用1種或組合2種以上而使用。 As the photopolymerization initiator, for example, benzyl, benzophenone or its derivatives, 9-oxysulfur

Ketals, benzyl dimethyl ketals, α-hydroxyalkyl phenones, α-hydroxyacetophenones, hydroxy ketones, amino alkyl phenones, phosphine oxides, etc. Among them, α-hydroxyalkyl phenones are hard to cause yellowing during hardening, and a transparent hardened product can be obtained, so it is preferable. In addition, amino alkyl phenones have very high reactivity and can obtain cured products with excellent hardness, so they are preferred. The said photopolymerization initiator can be used individually by 1 type or in combination of 2 or more types.

Regarding the addition amount of the photopolymerization initiator, it is preferable to add 0.1 to 5 parts by mass relative to 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 adjustment component.

As the leveling agent, a silicone-based leveling agent, an acrylic-based leveling agent, etc. can be cited. Among them, those having a reactive functional group at the terminal are more preferred, and those having two or more functions are more preferred. Reactive functional groups.

Specifically, examples include: polyether-modified polydimethylsiloxane having acrylic groups having double bonds at both ends, or polyether-modified polydimethylsiloxanes having acrylic groups each having 2 at each end and 4 double bonds in total. Ester modified polydimethylsiloxane, etc.

Among them, particularly preferred is a polyester-modified polydimethylsiloxane having an acrylic group that has a stable haze value and contributes to the improvement of scratch resistance.

The curable resin composition for forming the C layer may contain, in addition to the curable resin component, a lubricant such as a silicon-based compound, a fluorine-based compound, or a mixed compound thereof, or an antioxidant, within a range that does not impair the effects of the present invention Various additives such as UV absorbers, antistatic agents, flame retardants such as silicone compounds, fillers, glass fibers, and impact-resistant modifiers.

The thickness of the 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 even more preferably 5 μm or more or 20 μm or less, and particularly preferably 7 μm or more or 15 μm or less.

Here, if the thickness of the hard coat layer (C layer) is in the above range, abrasion resistance can be imparted, and cracks due to stress are unlikely to occur, which is preferable.

Moreover, when there are hard coats (layer C) on both sides, the thickness of each hard coat may be the same or different. Among them, 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 greater than the surface of the polycarbonate resin layer (layer B) The thickness of the hard coating.

<Layer structure of the front panel>

As long as the front panel has a layer structure with a thermoplastic resin layer (A layer) different from the polycarbonate resin on one side or both sides of the polycarbonate resin layer (layer B), other layers may also be provided . For example, as long as it is a laminated body which has an acrylic resin layer (A layer) on one side or both sides of a polycarbonate resin layer (B layer), it may be equipped with another layer.

Also, for example, as described above, the outermost surface on one side or the outermost surface on both sides may have Prepare hard coating (layer C).

As the layer structure 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), etc.

Here, when there are two or more layers of the same classification in the layer structure, the layers may have the same composition or different compositions.

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

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

<The thickness of the front panel>

In the front panel, the thickness (a ₁ ) of the front panel is not particularly limited. For example, it is preferably 0.1 mm to 3.0 mm, more preferably 1.5 mm or less, and further preferably 0.15 mm or more or 1.2 mm or less.

In addition, the thickness (a ₁ ) of the front panel also has a preferable range according to the application of the laminate. For example, when applied to the case of a housing material before various image display devices, it is preferably 0.1~2.0mm, and more preferably 0.15mm or more or 1.5mm or less, 0.2mm or more or 0.8mm or less, 0.2mm or more or 0.7 mm or less. If it is within this range, lightness, rigidity, and shape stability under a high temperature or high humidity environment are excellent, which is preferable.

In addition, when laminating an adhesive layer on the front panel to protect the surface of glass, etc. without stains or damage, or to prevent the scattering of broken fragments, 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.

Regardless of the application, in terms of reducing the internal stress (σ) of the laminate, the thickness (a ₁ ) of the front panel is preferably thinner. From this viewpoint, the thickness (a ₁ ) of the front panel is preferably 0.7 mm or less, more preferably 0.6 mm or less, and still more preferably 0.5 mm or less.

In this laminate, in order to suppress the internal stress generated under the high temperature and high humidity environment of the laminate, as well as the shape stability, the total thickness of the layer A should be as small as possible. On the other hand, in order to increase the surface hardness, it is preferably The thickness is greater than a certain level, and is preferably adjusted to an appropriate range according to the target physical properties.

From this viewpoint, the total thickness of the A layer is preferably 10 μm to 250 μm, more preferably 30 μm or more or 200 μm or less, and still more preferably 50 μm or more or 150 μm or less.

In addition, when the present laminated body is provided with, for example, two layers as the A layer, the total thickness of the two layers becomes the total thickness of the A layer.

In addition, 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 one layer of the thermoplastic resin layer A is relative to that of 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 still more preferably 0.10 or more or 0.30 or less.

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

<The elastic modulus of the front panel>

From the viewpoint of reducing the internal stress of the laminate under the high temperature and high humidity environment and improving the shape stability, the elastic modulus (E ₁ ) of the front panel is preferably 1500~4500 (MPa), and more preferably 1800 or more Or 4000 (MPa) or less, and among them, it is more preferably 2000 or more or 3500 (MPa) or less.

<Warpage amount of 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 above-mentioned front panel is allowed to stand for 120 hours in an environment with a temperature of 85°C and a humidity of 85%RH, and then at a temperature of 23°C , 4 hours after placed in an environment with a humidity of 50%RH The average amount of corner warpage 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) mentioned above is relatively large, the thickness of the front panel can be thinned, and the elastic modulus of the adhesive sheet can be reduced. Adjusting the stress (σ) to a specific range can improve the shape stability under high temperature and high humidity environments.

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

In order to adjust the amount of warpage (δ) of the front panel in the above range, it is preferable to reduce the total thickness of the A layer and adjust the thickness (A) of the first layer of the A layer relative to the total of the A layer and the B layer. The method of the ratio of layer thickness (T) ((A)/(T)), or the method of obtaining the balance of elastic modulus, hardening shrinkage, and thickness of the hard coating on the front and back. However, it is not limited to these methods.

<Manufacturing method of front panel>

As a method of forming a film when layering A and B, a known method can be used. From the viewpoint of operability or productivity, it is preferable to use an extruder with melt mixing equipment such as a single-screw extruder, a multi-screw extruder, a Banbury mixer, a kneader, and the like and a T-die head. The casting method.

As a layering method, a method of co-extrusion molding the melt-kneaded resin by a T-die with a feed module or a multi-manifold can be preferably used.

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

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

In addition, when extruding each layer, a single-screw extruder or a multi-screw extruder can be preferably used. As for the extruder of each layer, it is preferable to have an exhaust function and a filtering function. Exhaust function can be It is preferably used for drying of the resin composition used in each layer or removal of trace amounts of volatile components, etc., since a laminate with fewer defects such as bubbles can be obtained. In addition, there are various types of filtering functions. Specifically, a leaf disc filter, a pan filter, a cone filter, a candle filter, a cylindrical filter, etc. can be exemplified. Among them, a leaf disc filter that can easily ensure an effective filtering area is preferred. With the filtering function, foreign matter or fine gel matter can be removed, and a laminate with less appearance defects can be obtained, which is preferable.

Furthermore, the resin composition used to form each layer can be used by mixing the components in advance with a mixer such as a roller mixer, a V-type mixer, a Bamburi mixer, and an extruder. Each component is directly supplied to the supply port of the extruder, or further separately metered components are supplied to each supply port of an extruder with two or more supply ports.

Furthermore, a well-known method can be used for the mixing method of various additives. For example: (a) Prepare a masterbatch prepared by mixing various additives in a suitable base resin at a high concentration (as a representative content, about 3-60% by mass) in advance, and mix the masterbatch to The method of adjusting the concentration in the used resin; (b) The method of directly mixing various additives in the used resin, etc.

The following methods can be cited: coating the surface of the layer A or layer B (referred to as the "resin layer surface") laminated as described above to dissolve or disperse the curable resin composition for forming the C layer in an organic solvent After the paint is applied, a cured film is formed, which is formed and laminated on the surface of the resin layer. However, it is not limited to this method.

As a method for the surface area layer of the resin layer, a known method can be used. Examples include: lamination method using cover film, dip coating method, direct coating method, reverse coating method, kama coating method, roll coating method, spin coating method, wire bar coating method, extrusion Coating method, curtain coating method, spraying method, gravure coating method, etc. In addition, for example, a method of using a transfer sheet formed by forming a hard coat layer (C layer) on the release layer and laminating the hard coat layer (C layer) on the surface of the resin layer can also be adopted.

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

Furthermore, it is preferable that after the curable resin composition for forming layer C of the resin layer surface area layer, the curable resin composition is cured by irradiating energy rays such as electron beams, radiation, or ultraviolet rays, or the curable resin composition is heated by heating. The curable resin composition hardens. Among them, from the viewpoint of molding time and productivity, it is preferable to cure by ultraviolet irradiation.

Here, as a light source emitting ultraviolet rays, 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 ultra-high pressure mercury lamp, or a mercury xenon lamp can be used. Among them, the electrodeless high-pressure mercury lamp can easily obtain high-illuminance ultraviolet rays, and is beneficial to the hardening of the ultraviolet-curable resin, so it is preferred.

When the curable resin composition for forming layer C contains an ultraviolet curable resin and is cured by irradiating ultraviolet rays, the transparency to ultraviolet rays is high, so there are cases where the inside of the curable resin composition hardens quickly It progresses, but due to the hardening inhibition effect of oxygen (called oxygen inhibition), the surface hardening of the curable resin composition is slow. In view of the oxygen barrier, if the surroundings of the resin composition are placed in a nitrogen atmosphere by the supply of nitrogen, and then ultraviolet rays are irradiated, the curing of the surface of the resin composition and the curing of the inside can be performed quickly, which is preferable.

After a thermoplastic resin layer (layer A) is laminated on one side or both sides of the polycarbonate resin layer (layer B) to form a resin laminate, the resin laminate may be heat-treated.

As the heat treatment conditions, it is preferable to perform the treatment in a temperature range 5°C to 30°C lower than the glass transition temperature of the A layer, especially a temperature range of 5°C to 25°C lower, and especially a temperature range of 5°C to 20°C lower. The resin laminate is heat-treated.

In addition, the outermost surface of the front panel on one side or both sides can be treated with at least one of anti-reflection treatment, anti-fouling treatment, anti-static 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, the method of coating reflection reduction coating, the method of vapor deposition of dielectric film, and the coating of antistatic coating The method and so on.

<Adhesive Sheet>

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

(Adhesive composition)

The above-mentioned adhesive composition preferably contains an acrylic resin, a crosslinking monomer, a crosslinking initiator, a reaction catalyst and the like used as needed.

The acrylic resin used as the main component resin is preferably an acrylate polymer (including a copolymer).

Acrylate polymers (including copolymers) can appropriately adjust the glass transition temperature by the type, composition ratio, and polymerization conditions of the acrylic monomer or methacrylic monomer used to polymerize the acrylate polymer ( Tg) and other characteristics.

Examples of acrylic monomers or methacrylic monomers used to polymerize into acrylate polymers include 2-ethylhexyl acrylate, n-octyl acrylate, n-butyl acrylate, ethyl acrylate, and methacrylic acid. Methyl ester and so on. It is also possible to use vinyl acetate, hydroxyethyl acrylate, acrylic acid, glycidyl acrylate, acrylamide, acrylonitrile, methacrylonitrile, fluoroacrylate, which are copolymerized with hydrophilic groups or organic functional groups, etc. , Silicone acrylate, etc.

Among acrylate polymers, alkyl (meth)acrylate copolymers are particularly preferred.

As the (meth)acrylate component used to form the alkyl (meth)acrylate copolymer, that is, the alkyl acrylate or the alkyl methacrylate component, the alkyl group is preferably n-octyl or isooctyl One of alkyl acrylate or alkyl methacrylate of any one of, 2-ethylhexyl, n-butyl, isobutyl, methyl, ethyl, isopropyl or selected from these A mixture of more than 2 kinds.

As other ingredients, organic functions such as carboxyl group, hydroxyl group, glycidyl group and the like can also be used. Copolymerization of functional acrylate or methacrylate. Specifically, a monomer component obtained by appropriately combining the above-mentioned alkyl (meth)acrylate component and a (meth)acrylate component having an organic functional group as a starting material can be obtained by heat polymerization ( Meth) acrylate-based copolymer polymer.

Among them, one of alkyl acrylates such as isooctyl acrylate, n-octyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc., or a mixture of two or more selected from these, or It is obtained by copolymerizing at least one of isooctyl acrylate, n-octyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like with acrylic acid.

As a crosslinking monomer (also called a "crosslinking agent"), polyfunctional (meth)acrylates with more than two (meth)acrylic groups, two or more isocyanate groups, epoxy resins can be used Multifunctional organofunctional resins with organic functional groups such as cyanogen, melamine, diol, siloxane, amine, etc., and organometallic compounds with metal complexes such as zinc, aluminum, sodium, zirconium, and calcium.

If the example of the above-mentioned polyfunctional (meth)acrylate is cited, for example, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,9-nonanediol diacrylate can be cited. , Trimethylolpropane triacrylate, etc.

Regarding the content of the crosslinking monomer, it is only necessary to adjust it with other elements in a way to obtain the required retention force. Generally, it is 0.01-40.0 parts by mass, preferably 0.1-30.0 parts by mass relative to 100 parts by mass of the main component resin. Parts, it is particularly preferable to adjust within the range of the ratio of 0.5 to 30.0 parts by mass. However, this range can also be exceeded under the condition of achieving a balance with other factors.

When crosslinking acrylate polymers, if appropriate crosslinking initiators (peroxidation initiators, photoinitiators) or reaction catalysts (tertiary amine compounds, quaternary ammonium compounds, laurel Tin acid compounds, etc.) are more effective.

In the case of cross-linking by ultraviolet radiation (also referred to as "UV (Ultraviolet, ultraviolet) cross-linking"), it is preferable to prepare a photoinitiator.

As the photoinitiator, any one of a cleavage-type photoinitiator and 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, benzalkonium dimethyl ketal, and hydroxyacetophenone.

等。 On the other hand, as a hydrogen abstraction type photoinitiator, for example, benzophenone, Michelone, dibenzocycloheptanone, 2-ethylanthraquinone, isobutyl 9-oxysulfur

Wait.

However, it is not limited to the substances listed above.

Regarding the addition amount of the photoinitiator, it can be adjusted appropriately. Generally, it is preferably adjusted within the range of 0.05 to 5.0 parts by mass relative to 100 parts by mass of the main component resin, and preferably 1: The ratio of 1 and each photoinitiator of the hydrogen abstraction type and the cleavage type are used together. However, it is also possible to exceed this range in order to balance with other elements.

(Other additives)

In addition to the above-mentioned ingredients, pigments such as pigments or dyes with near-infrared absorption properties, adhesion imparting agents, antioxidants, anti-aging agents, moisture absorbents, ultraviolet absorbers, silane coupling agents, natural products or Various additives such as synthetic resins, glass fibers or glass beads.

Regarding the above-mentioned adhesive sheet, the adhesive sheet can be made by adding the acrylic resin as the main component resin, the crosslinking agent, the reaction initiator or the reaction catalyst, etc., as necessary, and stirring and mixing, A film is formed on the release film so as to have a target thickness, and it is crosslinked by heat drying or ultraviolet irradiation.

(thickness)

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

(Modulus of Elasticity)

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

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

The so-called tactile adhesion is defined as "the one that expresses the adhesive force at the moment of adhesion to the adherend", "there are many cases where it is qualitatively judged by fingers etc." (Kinumura, Makoto Sunagawa, etc., "High-performance Adhesion" Agents and Adhesives" Kyoritsu Publishing Co., Ltd. issued on February 20, 1989)

Furthermore, the elastic modulus (E ₂ ) of the adhesive sheet can be measured by using a tensile tester to perform a tensile test along the length of the cut adhesive sheet at a test speed of 300 mm/min.

(Tg)

The Tg of the adhesive sheet can be used with a rheometer (“MARS” manufactured by Yinghong Precision Machinery Co., Ltd.) in the adhesive fixture: Φ25mm parallel plate, strain: 0.5%, frequency: 1Hz, temperature: -50~200℃, heating rate: Measured by the loss tangent (tanδ) of the dynamic viscoelasticity measurement performed by the shear method under the condition of 3°C/min.

<Characteristics of this laminate>

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

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

δ: In the warped shape of the front panel only when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours, the front panel end face when the front panel is left horizontally in a protruding shape Height of bulge from resting surface

L: sample length (10cm)

θ: Only in the warped shape of the front panel when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours, from the front panel when the front panel is left horizontally in a protruding shape The angle formed by the vertical line that the center of curvature of the warped shape falls to the grounding point of the front panel and the straight line connecting the center of curvature of the warped shape of the front panel and the end point of the front panel

ρ ₁ ：The curvature radius of the front panel warped shape only when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours

a ₁ : The thickness of the front panel

a ₂ : The thickness of the adhesive sheet

b: sample width (10cm)

E ₁ : The elastic modulus of the front panel

E ₂ : The 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 test results conducted by the inventors, it can be confirmed that in this laminate, if the internal stress (σ) obtained by the above formula (1) and formula (2) is 0.47 MPa or less, the high temperature can be effectively suppressed Warpage in high humidity environment.

From this viewpoint, the internal stress (σ) in the present laminate is preferably 0.47 MPa or less, more preferably 0.46 MPa or less, and even more preferably 0.45 MPa or less. Furthermore, it is preferably 0.40 MPa or less, and more preferably 0.30 MPa or less.

The above-mentioned internal stress (σ) in this laminate can be mainly determined by the thickness of A layer, (A layer) 1 layer The ratio of the thickness (A) to the total thickness (T) of the (A) and (B) layers ((A)/(T)), the materials of the A and B layers, the thickness and materials of the adhesive sheet, etc. Make adjustments.

Furthermore, in the following examples, as a method for evaluating warpage in a high-temperature and high-humidity environment, an environment with a temperature of 85°C and a humidity of 85% RH is used as the high-temperature and high-humidity environment, but other environmental conditions, such as a temperature of 60 Environmental conditions such as ℃, humidity 90%RH, or temperature 70℃, humidity 90%RH are regarded as high temperature and high humidity environment.

<Use of this laminate>

As explained above, the present laminate has excellent 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 suitably used for various applications, for example, it can be bonded to a base material and used as various substrate materials, protective materials, and the like. In addition to various substrate materials or protective materials that are used as constituent materials for image display devices such as mobile phone terminals, smart phones, portable electronic game equipment, portable information terminals, tablet devices, mobile personal computers, wearable terminals, etc. It can also be preferably used as various substrate materials or protective materials as the constituent materials of set-up display devices such as LCD TVs, liquid crystal displays, desktop personal computers, car navigations, and car meters.

In addition, the present laminate can also be shaped by various processing methods. For example, in addition to the method of heating and pressurizing using a mold, a pressure forming method, a vacuum forming method, a roll forming method, etc. can also be exemplified as the forming method. By giving the shape to the laminate, it can be used for image display devices with curved surfaces or various flexible devices.

<Explanation of words, etc.>

Generally, the so-called "sheet" refers to a product that is thinner as defined in JIS and whose thickness and length are smaller and flat compared to the width and width. Generally, the so-called "film" refers to the thickness that is extremely small compared to the length and width. The thinner and flat products whose maximum thickness is arbitrarily limited are usually supplied in the form of rolls (Japanese Industrial Standard JISK6900). However, the boundary between the sheet and the film is not clear. In the present invention, there is no need to distinguish between the two in terms of words. Therefore, the present invention In this, even in the case of "film", it also includes "sheet", and even in the case of "sheet", it also includes "membrane".

In addition, when it is expressed as a "panel" such as an image display panel, a protection panel, etc., it includes a plate, a sheet, and a film, or a laminate of these.

In this manual, when it is described as "X~Y" (X, Y are arbitrary numbers), unless otherwise specified, it not only includes the meaning of "more than X and less than Y", but also includes "preferably The meaning of "greater than X" or "preferably less than Y".

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

[Example]

Hereinafter, a more detailed description will be given by using examples. However, the present invention is not limited to the examples described below.

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

(1) Thickness

A commercially available thickness measuring device (manufactured by MITUTOYO) was used for measurement.

(2) Elastic modulus (E ₁ , E ₂ )

For the elastic modulus (E1) of the front panel, use the dynamic viscoelasticity measuring method described in JISK-7198A method, using the dynamic viscoelasticity measuring device "DVA-200" manufactured by IT Meter and Control (stock). For the film The transverse direction (TD) is measured under the conditions of vibration frequency of 10Hz and strain of 0.1% at a heating rate of 1°C/min from -100°C to 200°C, and the storage elastic modulus at a temperature of 20°C is obtained from the obtained data (E'), use the storage elastic modulus (E') as E ₁ .

For the elastic modulus (E ₂ ) of the adhesive sheet, the test speed is 300mm/min along the length direction of the adhesive sheet cut out with a tensile testing machine and measured.

(3) The warpage evaluation of the front panel alone by the damp heat exposure test

The resin laminate (front panel) obtained in the Examples and Comparative Examples was cut into a size of 10cm×10cm, and placed in a constant temperature and humidity bath set at a temperature of 85°C and a humidity of 85%RH for 120 hours, and then set it to After being placed in a constant temperature and humidity bath with a temperature of 23°C and a humidity of 50%RH for 4 hours, the warpage of the four corners was evaluated immediately.

The amount of warpage is that the convex surface of the resin laminate (front panel) of the test piece is statically placed on the quartz platen, and the height of the four corners from the platen is visually measured using a height gauge to calculate the warpage amount δ( mm) average value.

(4) Calculation of internal stress

Cut the front panel obtained in the Examples and Comparative Examples into a size of 10cm×10cm, and use the formulas (1) and (2) shown below to calculate in a constant temperature and humidity tank set at a temperature of 85°C and a humidity of 85%RH Internal stress generated when exposed for 120 hours.

δ: In the warped shape of the front panel only when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours, the front panel end face when the front panel is left horizontally in a protruding shape Height of bulge from resting surface

L: sample length (10cm)

θ: Only in the warped shape of the front panel when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours, from the front panel when the front panel is left horizontally in a protruding shape The angle formed by the vertical line that the center of curvature of the warped shape falls to the grounding point of the front panel and the straight line connecting the center of curvature of the warped shape of the front panel and the end point of the front panel

ρ ₁ ：The curvature radius of the front panel warped shape only when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours

a ₁ : The thickness of the front panel

a ₂ : The thickness of the adhesive sheet

b: sample width (10cm)

E ₁ : The elastic modulus of the front panel

E ₂ : The 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 schematic diagram of the internal stress calculation model is shown in FIG. 1.

As the calculation process, firstly, the warpage (δ) of the front panel alone measured by the above-mentioned damp heat exposure test is substituted into the formula (1), and the calculation is calculated by using only the front panel at a temperature of 85°C and a humidity of 85%RH. _{The radius of curvature (ρ 1} ) of the warped shape of the front panel when exposed to the environment for 120 hours.

Then, according to the following formulas (3) and (4), the area second moments (I _1, I ₂ ) of the front panel and the adhesive are respectively calculated. Then, the calculated ρ ₁ and other physical property values are substituted into equation (2) to calculate the internal stress (σ).

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

The laminated body of the previous panel/adhesive sheet/glass obtained in the examples and comparative examples Place it in a constant temperature and humidity tank set at a temperature of 85°C and a humidity of 85%RH for 120 hours, and then place it in a constant temperature and humidity tank set at a temperature of 23°C and a humidity of 50%RH for 4 hours, then immediately confirm the test by visual inspection The appearance of the film.

At this time, if the amount of warpage of the front panel caused by exposure to moisture and heat is large, peeling will occur at the interface between the front panel and the adhesive sheet, and the appearance of poor appearance will be caused by the mixing of bubbles (air) in the peeled area. The size of the defective appearance portion was evaluated by visual observation in accordance with the following criteria.

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

×(Unsatisfactory): The area ratio of the defective appearance part is more than 10%

<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 (stock), 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 (manufactured by Electric Chemical Industry Co., Ltd., trade name: RESISSFY 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: 37.3N): 4.2g/10min)

(Thermoplastic resin (a3-1))

The molar ratio of the monomer unit derived from isosorbide which is a dihydroxy compound to the monomer unit derived from tricyclodecane dimethanol obtained by the method according to Japanese Patent Laid-Open No. 2008-024919 is isosorbide Ester/tricyclodecane dimethanol=70/30 mol% polycarbonate copolymer (density: 1.36g/cm ³ , Tg: 128°C, MFR (temperature: 230°C, load: 37.3N): 9.6g /10min)

(Polycarbonate resin (b1-1))

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

(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 ): 0.30MPa, Tg: -10°C.

(glass plate)

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

<Example 1>

100 parts by mass of a resin composition obtained by mixing 60 parts by mass of acrylic resin (a1-1) and 40 parts by mass of copolymer acrylic resin (a2-1), and 100 parts by mass of polycarbonate resin (b1-1) The parts are supplied to different extruders with exhaust function and filtering function, melted and kneaded at a resin temperature of 240~265℃, and used in the feed module as a layered structure of (A layer)/(B layer) After co-extrusion molding with a T-die at 260°C, it is cooled by the first cooling roll set at 100°C, the second cooling roll set at 110°C, and the third cooling roll set at 150°C. The total thickness is 0.675mm, and the thickness of each layer is (A layer)/(B layer)=0.075mm/0.600mm front panel.

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

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

Then, the adhesive surface exposed by peeling off the peeling film of one of the adhesive sheets was superimposed on the surface of the hard coat layer (Cb) of the front panel and pasted with a hand roller. Then, the remaining peeling film was peeled off, soda lime glass (thickness: 0.5mm) was superimposed on the exposed adhesive surface, and pressure bonding was carried out under reduced pressure (absolute pressure of 5kPa), and then subjected to autoclave treatment (50°C, 0.2 MPa, 20 minutes) bonding to produce a layered body. Furthermore, the laminate was irradiated with ultraviolet rays through soda lime glass using a high-pressure mercury lamp so that ultraviolet rays of 365 nm reached 2000 mJ/cm ^{2 to} harden the adhesive sheet to produce the above-mentioned front panel/adhesive sheet/glass laminate.

<Example 2, 3>

As shown in Table 1, in Example 1, the thickness ratio and total thickness of each layer of the A layer and B layer of the front panel were changed. Except for this, the front panel and the front panel/adhesive sheet were produced in the same manner as in Example 1. Material/glass fitting body.

<Example 4>

Supply 100 parts by mass of thermoplastic resin (a3-1) and polycarbonate resin (b1-1) by mass to different extruders with venting and filtering functions, and melt them at a resin temperature of 240~265°C Kneading and co-extrusion molding with a T-die with a multi-manifold to form a two-layer three-layer structure of (Af layer)/(B layer)/(Ab layer) using a T-die at 240°C After that, pass through the first cooling roll set at 100°C and the second cooling roll set at 110°C in sequence And set the third cooling roll at 120°C to cool it to obtain a total thickness of 0.675mm, and the thickness of each layer is (Af layer)/(B layer)/(Ab layer)=0.075mm/0.525mm/0.075mm before the panel, After that, a hard coat layer was applied in the same manner as in Example 1 to produce a bonded body of front panel/adhesive sheet/glass.

<Example 5>

Supply 100 parts by mass of thermoplastic resin (a3-1) and polycarbonate resin (b1-1) by mass to different extruders with venting and filtering functions, and melt them at a resin temperature of 240~265°C Kneading and co-extrusion molding with a T-die with a multi-manifold to form a two-layer three-layer structure of (Af layer)/(B layer)/(Ab layer) using a T-die at 240°C After that, it was cooled by the first cooling roll set at 100°C, the second cooling roll set at 110°C, and the third cooling roll set at 120°C in order to obtain a total thickness of 0.275mm, and the thickness of each layer was (Af Layer)/(Layer B)/(Layer Ab)=0.075mm/0.125mm/0.075mm front panel, after that, a hard coat was applied in the same manner as in Example 1 to produce front panel/adhesive sheet/glass The fit body.

<Comparative Examples 1~4>

As shown in Table 1, in Example 1, the thickness ratio and total thickness of the A layer and B layer of the front panel were changed. Except for this, the front panel was obtained in the same manner as in Example 1. After that, the front panel was produced. Adhesive sheet/glass body.

<Comparative Examples 5 and 6>

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

<Comparative Examples 7, 8>

As shown in Table 1, in Example 1, the temperature of the third cooling roll was changed during the co-extrusion molding of the front panel. Except for this, the front panel was obtained in the same manner as in Example 1. Thereafter, the front panel/ Adhesive sheet/glass body.

As shown in Tables 1 and 2, in the constitution of Examples 1 to 5, the peeling in the non-humid heat environment test was a good result. On the other hand, in Comparative Examples 1 to 8, peeling occurred.

It is believed that there is a correlation between the peeling behavior during the hot and humid environment test and the internal stress σ calculated using equations (1) and (2). It can be confirmed that if the internal stress σ is less than a certain value, it can be suppressed during the hot and humid environment test.之 stripping. It is considered that the reason is that if the internal stress due to warpage generated when only the front panel is subjected to the damp heat exposure test is reduced to a certain level or less, the adhesion force with the adhesive sheet prevails and peeling can be suppressed. It can be confirmed that the internal stress: 0.47 MPa is roughly the threshold for peeling.

As the factors affecting the internal stress of the front panel, according to formula (1) and formula (2), elastic modulus, thickness, and warpage can be listed. Among them, the internal stress can be reduced mainly by thinning the thickness or reducing the amount of warpage. Even if any one of them is larger, the internal stress can be reduced by adjusting the other parameter to an appropriate range, thereby suppressing peeling.

As a method to reduce the amount of warpage, processing conditions such as adjustment of the layer composition 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 coatings, and the roll temperature conditions at the time of manufacturing, etc.的方法。 The method.

Among them, the method of making the layer structure of the A layer and the B layer into a two-type three-layer symmetrical structure of A layer/B layer/A layer is more effective. By adopting a symmetrical structure, the difference between the expansion and contraction behavior of the A layer and the B layer can be eliminated on the front and back, so it is more effective for reducing the warpage.

From Examples 4 and 5, it can be confirmed that the amount of warpage of the front panel can be compared with the two types of two-layer structure of A-layer/B-layer with respect to the front panel adopting two types of three-layer symmetrical structure And the internal stress is suppressed to be small.

As another method to reduce the amount of warpage, the thickness (A) of one layer (A) in the two-layer structure of A layer/B layer is relative to the total thickness of (A) layer and (B) layer (T The method of reducing the ratio ((A)/(T)) of) is more effective. Since the warpage is caused by the difference in the expansion and contraction behavior of the two layers, for example, if the A layer is made extremely thin and the thickness ratio becomes non-uniform in a manner close to the single layer of the B layer, the A layer The effect will be difficult to show, so the warping behavior can be suppressed.

As another method to reduce the amount of warpage, it is more effective to make the composition of the hard coat layer (C layer) on the front and back surfaces 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 the cause of warpage. Therefore, in order to suppress the warpage, it is better to obtain the hard coat layer on the front and back sides. Composition is the balance of material and thickness.

When the material composition of the hard coat is the same on the front and back, it is better to make the thickness of the two close. When the material composition of the hard coat is different on the front and back, it is better to consider the decision of each hard coat. Adjust the thickness by balancing the elastic modulus of the material and the amount of hardening shrinkage.

As another method to reduce the amount of warpage, it is more effective to reduce the thermal strain during the cooling process by adjusting the film forming conditions during co-extrusion. For example, by increasing the temperature of the third cooling roll within a range that does not cause poor appearance, the thermal strain can be reduced by the annealing effect.

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

In Comparative Example 1, the total thickness is thick, 1000 μm. Even when the amount of warpage is small, the internal stress becomes large due to the large influence of the thickness.

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

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

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

δ‧‧‧The bulge height of the end surface of the front panel from the resting surface

L‧‧‧Sample length

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

θ‧‧‧The angle formed by the vertical line falling from the center of curvature of the front panel to the grounding point of the front panel and the straight line connecting the center of curvature of the front panel with the end point of the front panel

10‧‧‧Front Panel

20‧‧‧Adhesive sheet

Claims (10)

A laminated body characterized in that it includes a front panel and an adhesive sheet; and the front panel includes a layer B mainly composed of a polycarbonate resin, and a thermoplastic resin that is different from the polycarbonate resin A layer of thermoplastic resin with resin as the main component, the total thickness of the A layer is 10μm~250μm, the ratio of the thickness (A) of the above A layer 1 layer to the total thickness (T) of the above A layer and the above B layer ((A )/(T)) is 0.05~0.40, the elastic modulus (E ₂ ) of the above-mentioned adhesive sheet is 0.001~30MPa, and the front panel and the adhesive sheet are calculated by the following formulas (1) and (2) The internal stress (σ) of the front panel and the adhesive sheet when the laminated body of the material is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours is 0.47MPa or less:

δ: In the warped shape of the front panel only when the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours, the front panel end face when the front panel is left horizontally in a protruding shape Protrusion height from the resting surface L: Sample length (10cm) θ: In the warped shape of the front panel when only the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours, the front panel is When the downwardly protruding shape is placed horizontally, it is formed by a vertical line falling from the center of curvature of the front panel to the grounding point of the front panel and a straight line connecting the center of curvature of the front panel with the end point of the front panel. The angle ρ ₁ : the curvature radius of the front panel warped shape when only the front panel is exposed to an environment with a temperature of 85°C and a humidity of 85%RH for 120 hours a ₁ : the thickness of the front panel a ₂ : of the adhesive sheet Thickness b: sample width (10cm) E ₁ : elastic modulus of the front panel E ₂ : elastic modulus of the adhesive sheet I ₁ : second moment of area of the front panel I ₂ : second moment of the area of the adhesive sheet h: a ₁ +a ₂ σ: internal stress. Such as the laminate of claim 1, in which the above-mentioned front panel is allowed to stand for 120 hours in an environment with a temperature of 85°C and a humidity of 85%RH, and then placed in an environment with a temperature of 23°C and a humidity of 50%RH for 4 hours. The average value of the amount of warpage (δ) is 1.5mm or less. The laminate of claim 1 or 2, wherein the thermoplastic resin as the main component resin of the A layer is an acrylic resin. Such as the laminate of claim 1 or 2, wherein the thermoplastic resin as the main component resin of the A layer contains methyl methacrylate monomer, methacrylic acid monomer, acrylic acid monomer, maleic anhydride monomer, and aromatic vinyl Acrylic resin (a1) which is a copolymer of any one or more of base monomers and acrylonitrile monomers. Such as the laminate of claim 1 or 2, wherein the thermoplastic resin as the main component resin of the A layer contains: acrylic resin (a1), which contains methyl methacrylate monomers, methacrylic monomers, acrylic monomers, Copolymers of any one or more of maleic anhydride monomers, aromatic vinyl monomers, and acrylonitrile monomers; and copolymers (a2) having aromatic vinyl monomer units and (meth)acrylate monomers Body unit and maleic anhydride monomer. The laminate of claim 1 or 2, wherein the thermoplastic resin as the main component of the A layer contains a polycarbonate resin (a3) derived from the structural unit of the dihydroxy compound represented by the following (Chemical 1) in a part of the structure ):

Such as the laminate of claim 1 or 2, wherein the polycarbonate resin as the main component resin of the B layer contains polycarbonate resin (b1) and 5 to 80% of aromatic (meth)acrylate monomers The acrylic copolymer (b2) is composed of 95 to 20% by mass of methyl methacrylate monomer units. Such as the laminate of claim 1 or 2, wherein the total thickness of the front panel is 0.7 mm or less. Such as the laminate of claim 1 or 2, wherein the front panel, in addition to the A layer and the B layer, on the side of the adhesive sheet laminated layer, further includes the same resin as the main component resin of the adhesive sheet as the main component The hard coating. An image display device provided with a laminate as claimed in any one of claims 1 to 9.

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