CN109153245B

CN109153245B - Resin laminate, display device, and polarizing plate

Info

Publication number: CN109153245B
Application number: CN201780032646.XA
Authority: CN
Inventors: 大松一喜; 大关美保; 山下恭弘
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2016-05-30
Filing date: 2017-05-22
Publication date: 2020-05-05
Anticipated expiration: 2037-05-22
Also published as: JP6503410B2; TW201808638A; JP2017213879A; KR20190007071A; WO2017208881A1; KR102008473B1; CN109153245A

Abstract

The invention provides a resin laminate which is not easy to warp and can be suitably used in a display device. A resin laminate comprising at least an intermediate layer (A) and thermoplastic resin layers (B) and (C) respectively present on both sides of the intermediate layer (A), wherein the intermediate layer (A) comprises 10 to 90 mass% of a (meth) acrylic resin and 90 to 10 mass% of a vinylidene fluoride resin based on the total resin contained in the intermediate layer (A), the (meth) acrylic resin has a weight average molecular weight of 100,000 to 300,000, and the thermoplastic resin layers (B) and (C) satisfy a specific relationship.

Description

Resin laminate, display device, and polarizing plate

Technical Field

The present invention relates to a resin laminate suitably used for a display device, a display device including the resin laminate, and a polarizing plate with a resin laminate obtained by laminating the resin laminate and a polarizing plate.

Background

In recent years, display devices including touch panels have been increasing in display devices such as smart phones, portable game machines, audio players, and tablet terminals. In general, glass sheets are used for the surface of such display devices, but from the viewpoint of weight reduction and workability of the display devices, plastic sheets have been developed as substitutes for the glass sheets. For example, patent document 1 discloses a transparent sheet containing a methacrylic resin and a vinylidene fluoride resin as a plastic sheet that is a substitute for a glass sheet.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-244604

Disclosure of Invention

Problems to be solved by the invention

Display devices are used in a variety of environments due to their high versatility. When a display device including a plastic sheet is used in a severe environment such as high temperature and high humidity, for example, warpage may occur due to expansion and contraction of the resin. In recent years, thinning of a display device is desired, and warping becomes a greater problem. The purpose of the present invention is to provide a resin laminate which is less likely to warp and which can be suitably used in a display device.

Means for solving the problems

In order to solve the above problems, the inventors of the present application have made extensive and intensive studies on a resin laminate that can be suitably used in a display device, and have completed the present invention.

That is, the present invention includes the following preferred embodiments.

[1] A resin laminate comprising at least an intermediate layer (A) and thermoplastic resin layers (B) and (C) respectively present on both sides of the intermediate layer (A),

the intermediate layer (A) contains 10 to 90 mass% of a (meth) acrylic resin and 90 to 10 mass% of a vinylidene fluoride resin based on the total resins contained in the intermediate layer (A), the (meth) acrylic resin having a weight average molecular weight (Mw) of 100,000 to 300,000,

the thermoplastic resin layers (B) and (C) satisfy the following relationships.

ΔL＝|L_B-L_C|≤20μm

Δλ_BC＝|Δλ_B-Δλ_C|≤0.19×10^-4

ΔT＝|T_B-T_C|≤4℃

[ in the formula, L_BAnd L_CRespectively represents the average film thicknesses of the thermoplastic resin layers (B) and (C), Delta lambda_BAnd delta lambda_CAre respectively provided withIs represented by the following formula (I),

Δλ_B＝|λ’_B-λ_B|

Δλ_C＝|λ’_C-λ_C|

in the above formula, λ'_BAnd λ'_CRespectively shows birefringence values (I), (lambda) measured for the thermoplastic resin layers (B) and (C) in the resin laminate_BAnd lambda_CRespectively shows birefringence values (II), T, measured for the thermoplastic resin layers (B) and (C) in the resin laminate after annealing treatment at a temperature 25 ℃ lower than the Vicat softening temperature of the thermoplastic resin layers (B) and (C) for 4 hours_BAnd T_CThe Vicat softening temperatures of the thermoplastic resin layers (B) and (C) are shown, respectively.]

[2] The resin laminate according to the above [1], wherein the intermediate layer (A) comprises 35 to 45 mass% of a (meth) acrylic resin and 65 to 55 mass% of a vinylidene fluoride resin based on the total resins contained in the intermediate layer (A).

[3] The resin laminate according to the above [1] or [2], wherein the content of the alkali metal in the intermediate layer (A) is 50ppm or less based on the total resin contained in the intermediate layer (A).

[4] The resin laminate according to any one of the above [1] to [3], wherein the (meth) acrylic resin is:

(a1) homopolymers of methyl methacrylate; and/or

(a2) A copolymer comprising 50 to 99.9 mass% of a structural unit derived from methyl methacrylate and 0.1 to 50 mass% of at least 1 structural unit derived from a (meth) acrylate represented by the following formula (1) based on the total structural units constituting the polymer.

[ chemical formula 1]

[ in the formula, R₁Represents a hydrogen atom or a methyl group, R₁When it is a hydrogen atom, R₂Represents an alkyl group having 1 to 8 carbon atoms, R₁When it is methyl, R₂Represents an alkyl group having 2 to 8 carbon atoms.]

[5] The resin laminate according to any one of the above [1] to [4], wherein the vinylidene fluoride resin is polyvinylidene fluoride.

[6] The resin laminate according to any one of the above [1] to [5], wherein the vinylidene fluoride resin has a melt mass flow rate of 0.1 to 40g/10 min as measured under a load of 3.8kg and at 230 ℃.

[7] The resin laminate according to any one of the above [1] to [6], wherein the average film thickness of the resin laminate is 100 to 2000 μm, and the average film thicknesses of the thermoplastic resin layers (B) and (C) are 10 to 200 μm, respectively.

[8] The resin laminate as described in any one of the above [1] to [7], wherein the vicat softening temperatures of the thermoplastic resins contained in the thermoplastic resin layers (B) and (C) are 100 to 160 ℃.

[9] The resin laminate according to any one of the above [1] to [8], wherein the thermoplastic resin layers (B) and (C) are (meth) acrylic resin layers or polycarbonate resin layers.

[10] The resin laminate according to any one of the above [1] to [9], wherein the thermoplastic resin layers (B) and (C) are polycarbonate resin layers and contain an ultraviolet absorber in an amount of 0.005 to 2.0 mass% based on the total resin contained in each thermoplastic resin layer.

[11] The resin laminate according to any one of the above [1] to [9], wherein the thermoplastic resin layers (B) and (C) contain a (meth) acrylic resin in an amount of 50 mass% or more based on the total resin contained in each thermoplastic resin layer.

[12] The resin laminate according to [11], wherein the (meth) acrylic resin contained in the thermoplastic resin layers (B) and (C) has a weight average molecular weight of 50,000 to 300,000.

[13] A display device comprising the resin laminate according to any one of [1] to [12 ].

[14] A polarizing plate with a resin laminate, which is obtained by laminating the resin laminate according to any one of the above [1] to [12] and a polarizing plate.

[15] A display device comprising the polarizing plate with a resin laminate according to [14 ].

ADVANTAGEOUS EFFECTS OF INVENTION

The resin laminate of the present invention is less likely to warp even when used in an environment such as high temperature and high humidity, and can be suitably used for a display device or the like.

Drawings

FIG. 1 is a schematic view of an apparatus for producing a resin laminate of the present invention used in examples.

FIG. 2 is a schematic cross-sectional view showing a preferred embodiment of a liquid crystal display device comprising the resin laminate of the present invention.

Detailed Description

The resin laminate of the present invention has at least an intermediate layer (a) and thermoplastic resin layers (B) and (C) respectively present on both sides of the intermediate layer (a). In other words, the resin laminate of the present invention has a structure in which at least the thermoplastic resin layer (B)/the intermediate layer (a)/the thermoplastic resin layer (C) are sequentially laminated.

The intermediate layer (A) contains 10-90 mass% of (meth) acrylic resin and 90-10 mass% of vinylidene fluoride resin based on the total resin contained in the intermediate layer (A). When the amount of the (meth) acrylic resin is less than the lower limit, sufficient transparency cannot be obtained, and when the amount of the (meth) acrylic resin is more than the upper limit, sufficient dielectric constant cannot be obtained. When the amount of the vinylidene fluoride resin is less than the lower limit, a sufficient dielectric constant cannot be obtained, and when the amount of the vinylidene fluoride resin is more than the upper limit, durability and sufficient transparency cannot be obtained.

The intermediate layer (a) preferably contains 30 to 60 mass% of a (meth) acrylic resin and 70 to 40 mass% of a vinylidene fluoride resin, more preferably contains 35 to 45 mass% of a (meth) acrylic resin and 65 to 55 mass% of a vinylidene fluoride resin, even more preferably contains 37 to 45 mass% of a (meth) acrylic resin and 63 to 55 mass% of a vinylidene fluoride resin, particularly preferably contains 38 to 45 mass% of a (meth) acrylic resin and 62 to 55 mass% of a vinylidene fluoride resin, and very particularly preferably contains 38 to 43 mass% of a (meth) acrylic resin and 62 to 57 mass% of a vinylidene fluoride resin, based on the total resins contained in the intermediate layer (a), from the viewpoint of easily improving the dielectric constant and easily improving the transparency of the resin laminate.

Examples of the (meth) acrylic resin contained in the intermediate layer (a) of the resin laminate of the present invention include homopolymers of (meth) acrylic monomers such as (meth) acrylic acid esters and (meth) acrylonitrile, copolymers of 2 or more (meth) acrylic monomers, and copolymers of (meth) acrylic monomers and monomers other than (meth) acrylic monomers. In the present specification, the term "(meth) acryl-" means "acryl-" or "methacryl-".

The (meth) acrylic resin is preferably a methacrylic resin from the viewpoint of easily improving the hardness, weather resistance and transparency of the resin laminate. The methacrylic resin is a polymer of a monomer mainly composed of a methacrylic acid ester (also referred to as an alkyl methacrylate), and examples thereof include a homopolymer of a methacrylic acid ester (also referred to as an alkyl methacrylate), a copolymer of 2 or more methacrylic acid esters, a copolymer of 50 mass% or more of a methacrylic acid ester and 50 mass% or less of a monomer other than a methacrylic acid ester, and the like. As the copolymer of a methacrylate ester and a monomer other than a methacrylate ester, a copolymer of a methacrylate ester of 70 mass% or more and another monomer of 30 mass% or less with respect to the total amount of monomers is preferable, and a copolymer of a methacrylate ester of 90 mass% or more and another monomer of 10 mass% or less is more preferable, from the viewpoint of easily improving optical properties and weatherability.

Examples of the monomer other than the methacrylate ester include acrylate esters and monofunctional monomers having 1 polymerizable carbon-carbon double bond in the molecule.

Examples of the monofunctional monomer include styrene monomers such as styrene, α -methylstyrene and vinyltoluene, alkenyl cyanides such as acrylonitrile and methacrylonitrile, acrylic acid, methacrylic acid, maleic anhydride, and N-substituted maleimide.

In the (meth) acrylic resin, from the viewpoint of heat resistance, N-substituted maleimide such as phenylmaleimide, cyclohexylmaleimide, and methylmaleimide may be copolymerized, and a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, or the like may be introduced into the molecular chain (also referred to as the main skeleton or main chain in the polymer).

From the viewpoint of easily improving the hardness, weather resistance and transparency of the resin laminate, specifically, the (meth) acrylic resin is preferably:

(a1) homopolymers of methyl methacrylate; and/or

(a2) A copolymer comprising 50 to 99.9 mass% (preferably 70.0 to 99.8 mass%, more preferably 80.0 to 99.7 mass%) of a structural unit derived from methyl methacrylate and 0.1 to 50 mass% (preferably 0.2 to 30 mass%, more preferably 0.3 to 20 mass%) of at least 1 structural unit derived from a (meth) acrylate represented by the following formula (1) based on the total structural units constituting the copolymer. Here, the content of each structural unit can be calculated by: the obtained polymer was analyzed by pyrolysis gas chromatography, and the peak area corresponding to each monomer was measured.

[ chemical formula 2]

In the formula (1), R₁Represents a hydrogen atom or a methyl group, R₁When it is a hydrogen atom, R₂Represents an alkyl group having 1 to 8 carbon atoms, R₁When it is methyl, R₂Represents an alkyl group having 2 to 8 carbon atoms. Examples of the alkyl group having 2 to 8 carbon atoms include ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group and the like. From the viewpoint of heat resistanceConsider that R₂Preferably an alkyl group having 2 to 4 carbon atoms, and more preferably an ethyl group.

The weight average molecular weight (hereinafter, sometimes referred to as Mw) of the (meth) acrylic resin contained in the intermediate layer (A) is 100,000 to 300,000. When Mw is less than the lower limit, transparency when exposed to a high-temperature and high-humidity environment is insufficient, and when Mw is more than the upper limit, film formability in the production of a resin laminate cannot be obtained. The Mw of the (meth) acrylic resin is preferably 120,000 or more, and more preferably 150,000 or more, from the viewpoint of easily improving transparency when exposed to a high-temperature and high-humidity environment. From the viewpoint of film formability in the production of the resin laminate, the Mw of the (meth) acrylic resin is preferably 250,000 or less, and more preferably 200,000 or less. The weight average molecular weight can be measured by Gel Permeation Chromatography (GPC) measurement.

The (meth) acrylic resin generally has a melt mass flow rate (hereinafter sometimes referred to as MFR) of 0.1 to 20g/10 min, preferably 0.2 to 5g/10 min, more preferably 0.5 to 3g/10 min, as measured under a load of 3.8kg and at 230 ℃. Since the strength of the obtained film is easily improved, the MFR is preferably not more than the upper limit, and from the viewpoint of film forming properties of the resin laminate, the MFR is preferably not less than the lower limit. MFR may be determined in accordance with JIS K7210: 1999 "test methods for melt Mass Flow Rate (MFR) and melt volume flow Rate (MVR) of Plastic-thermoplastics". The poly (methyl methacrylate) -based material was measured under the conditions of a temperature of 230 ℃ and a load of 3.80kg (37.3N) as specified in JIS.

From the viewpoint of heat resistance, the (meth) acrylic resin has a vicat softening temperature (hereinafter sometimes referred to as VST) of preferably 90 ℃ or higher, more preferably 100 ℃ or higher, and still more preferably 102 ℃ or higher. The upper limit of VST is not particularly limited, and is usually 150 ℃ or lower. VST may be measured according to JIS K7206: 1999. the measurement was carried out by the method B50 described therein. The VST can be adjusted to the above range by adjusting the kind of the monomer, the ratio thereof.

The (meth) acrylic resin can be prepared by polymerizing the above-mentioned monomers by a known method such as suspension polymerization, bulk polymerization, or the like. At this time, MFR, Mw, VST, etc. can be adjusted to a preferable range by adding an appropriate chain transfer agent. As the chain transfer agent, a commercially available product can be suitably used. The amount of the chain transfer agent to be added may be appropriately determined depending on the kind of the monomer, the ratio thereof, the desired characteristics, and the like.

Examples of the vinylidene fluoride resin contained in the intermediate layer (a) of the resin laminate of the present invention include homopolymers of vinylidene fluoride and copolymers of vinylidene fluoride and other monomers. From the viewpoint of easily improving the transparency of the obtained resin laminate, the vinylidene fluoride resin is preferably a copolymer of at least 1 monomer selected from the group consisting of trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, perfluoroalkyl vinyl ether and ethylene and vinylidene fluoride, and/or a homopolymer of vinylidene fluoride (polyvinylidene fluoride), and more preferably polyvinylidene fluoride.

The vinylidene fluoride resin contained in the intermediate layer (A) has a weight average molecular weight (Mw) of preferably 100,000 to 500,000, more preferably 150,000 to 450,000, still more preferably 200,000 to 450,000, and particularly preferably 350,000 to 450,000. When Mw is not less than the above lower limit, the transparency of the resin laminate of the present invention is easily improved when the resin laminate is exposed to a high-temperature and high-humidity environment (for example, 60 ℃ c, 90% relative humidity), and therefore, it is preferable. When Mw is not more than the above upper limit, the film formability of the resin laminate is easily improved, and therefore, Mw is preferable. The weight average molecular weight can be measured by Gel Permeation Chromatography (GPC) measurement.

The vinylidene fluoride resin has a melt Mass Flow Rate (MFR) of preferably 0.1 to 40g/10 min, more preferably 0.1 to 30g/10 min, still more preferably 0.1 to 25g/10 min, as measured under a load of 3.8kg and at 230 ℃. The MFR is more preferably 0.2g/10 min or more, and still more preferably 0.5g/10 min or more. The MFR is more preferably 20g/10 min or less, still more preferably 5g/10 min or less, and particularly preferably 2g/10 min or less. When the MFR is not more than the upper limit, it is preferable because the decrease in transparency is easily suppressed when the resin laminate is used for a long period of time. When the MFR is not less than the above lower limit, the film formability of the resin laminate is easily improved, and therefore, it is preferable. MFR may be determined in accordance with JIS K7210: 1999 "test methods for melt Mass Flow Rate (MFR) and melt volume flow Rate (MVR) of Plastic-thermoplastics".

Vinylidene fluoride resins can be industrially produced by suspension polymerization or emulsion polymerization. The suspension polymerization process can be carried out by: dispersing a monomer in a medium in the form of droplets by using water as a medium and a dispersant, and polymerizing an organic peroxide dissolved in the monomer as a polymerization initiator; a granular polymer having a particle size of 100 to 300 μm can be obtained. The suspension polymer is preferred because it is simpler in production process and superior in handling property of powder as compared with the emulsion polymer, and it does not contain an alkali metal-containing emulsifier or salting-out agent as in the case of the emulsion polymer.

As the vinylidene fluoride resin, commercially available products can be used. Examples of preferable commercially available products include "KF Polymer (registered trademark) T #1300, T #1100, T #1000, T #850, W #1000, W #1100 and W # 1300" of KUREHA, "SOLEF (registered trademark) 6012, 6010 and 6008" of Solvay corporation.

The intermediate layer (a) may further contain another resin different from the (meth) acrylic resin and the vinylidene fluoride resin. When other resin is contained, the kind thereof is not particularly limited as long as the transparency of the resin laminate is not significantly impaired. From the viewpoint of the hardness and the weatherability of the resin laminate, the amount of the other resin is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total resin contained in the intermediate layer (a). Examples of the other resin include polycarbonate resin, polyamide resin, acrylonitrile-styrene copolymer, methyl methacrylate-styrene copolymer, and polyethylene terephthalate. The intermediate layer (a) may further contain another resin, but the amount of the other resin is preferably 1 mass% or less from the viewpoint of transparency, and the resin contained in the intermediate layer (a) is more preferably only a (meth) acrylic resin and a vinylidene fluoride resin.

The content of the alkali metal in the intermediate layer (a) is preferably 50ppm or less, more preferably 30ppm or less, further more preferably 10ppm or less, and particularly preferably 1ppm or less, based on the entire resin contained in the intermediate layer (a). When the content of the alkali metal in the intermediate layer (a) is not more than the above upper limit, the decrease in transparency when the resin laminate is used for a long period of time under a high-temperature and high-humidity environment is easily suppressed, and therefore, the content is preferable. The lower limit of the content of the alkali metal in the intermediate layer (a) is 0, and it is very preferable that the resin laminate contains substantially no alkali metal from the viewpoint of easily suppressing the decrease in transparency of the resin laminate. Here, a trace amount of an emulsifier used in the production process and the like remains in the (meth) acrylic resin and/or the vinylidene fluoride resin contained in the intermediate layer (a). Therefore, the alkali metal such as sodium and potassium derived from the residual emulsifier is contained in the intermediate layer (a) in an amount of, for example, 0.05ppm or more. In particular, when the (meth) acrylic resin and/or vinylidene fluoride resin contained in the intermediate layer (a) is obtained by emulsion polymerization, the amount of the emulsifier remaining in the resin increases, and the content of the alkali metal in the intermediate layer (a) also increases. From the viewpoint of easily suppressing the decrease in the transparency of the resin laminate, it is preferable to use a resin having a small alkali metal content as the (meth) acrylic resin and the vinylidene fluoride resin contained in the intermediate layer (a).

In order to control the content of the alkali metal in the resin within the above range, the amount of the compound containing the alkali metal may be reduced or the washing step after the polymerization may be increased to remove the compound containing the alkali metal when the resin is polymerized. The content of the alkali metal can be determined by inductively coupled plasma mass spectrometry (ICP/MS), for example. As the inductively coupled plasma mass spectrometry, for example, a sample to be measured is ashed by an appropriate method such as a high-temperature ashing melting method, a high-temperature ashing acid dissolution method, a Ca-addition ashing acid dissolution method, a combustion absorption method, or a low-temperature ashing acid dissolution method, and the like, and is dissolved in an acid, and the dissolved solution is fixed in volume, and the alkali metal content is measured by inductively coupled plasma mass spectrometry.

The resin laminate of the present invention has at least thermoplastic resin layers (B) and (C) present on both sides of an intermediate layer (a). The thermoplastic resin layer (B) and the thermoplastic resin layer (C) may be the same layer or different layers from each other.

The thermoplastic resin layers (B) and (C) contain at least 1 thermoplastic resin. From the viewpoint of ease of improvement in molding processability, the thermoplastic resin layers (B) and (C) contain preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more of the thermoplastic resin based on the total resin contained in each thermoplastic resin layer. The upper limit of the amount of the thermoplastic resin is 100 mass%. Examples of the thermoplastic resin include (meth) acrylic resins, polycarbonate resins, cycloolefin resins, and the like. The thermoplastic resin is preferably a (meth) acrylic resin or a polycarbonate resin from the viewpoint of easily improving the adhesion between the thermoplastic resin layers (B) and (C) and the intermediate layer (a). The thermoplastic resin layers (B) and (C) may contain the same thermoplastic resin or different thermoplastic resins. From the viewpoint of easily suppressing the warpage of the resin laminate, the thermoplastic resin layers (B) and (C) preferably contain the same thermoplastic resin.

From the viewpoint of heat resistance of the resin laminate, the resin laminate is produced according to JIS K7206: 1999, the thermoplastic resins contained in the thermoplastic resin layers (B) and (C) have Vicat softening temperatures of preferably 100 to 160 ℃, more preferably 102 to 155 ℃, and still more preferably 102 to 152 ℃. Here, when the thermoplastic resin layer contains 1 kind of thermoplastic resin, the vicat softening temperature is the vicat softening temperature of the resin, and when the thermoplastic resin layer contains 2 or more kinds of thermoplastic resins, the vicat softening temperature is the vicat softening temperature of a mixture of a plurality of kinds of thermoplastic resins.

The thermoplastic resin layers (B) and (C) may further contain other resins (for example, thermosetting resins such as fillers and resin particles) than the thermoplastic resin for the purpose of improving the strength, elasticity, and the like of the thermoplastic resin layers. In this case, the amount of the other resin is preferably 40% by mass or less, more preferably 30% by mass or less, and further more preferably 20% by mass or less, based on the total resin contained in each thermoplastic resin layer. The lower limit of the amount of the other resin is 0 mass%.

In the resin laminate of the present invention, the thermoplastic resin layers (B) and (C) satisfy the following relationship.

ΔL＝|L_B-L_C|≤20μm

[ in the formula, L_BAnd L_CThe average film thicknesses of the thermoplastic resin layers (B) and (C) are shown, respectively.]

From the viewpoint of easily suppressing the warpage of the resin laminate of the present invention, Δ L is preferably 17 μm or less, and more preferably 15 μm or less. Δ L represents the difference between the average film thicknesses of the thermoplastic resin layers (B) and (C), and Δ L can be adjusted to fall within the above range by adjusting the film thicknesses of the thermoplastic resin layers (B) and (C), respectively. Here, the film thickness of the thermoplastic resin layer can be measured using a microscope (for example, a microscope made by Micro Square, inc.). The average value of the values obtained by the above measurement at any 10 points of the thermoplastic resin layer was defined as the average value of the film thickness. Since Δ L is an absolute value, the lower limit thereof is 0 μm.

In the resin laminate of the present invention, the thermoplastic resin layers (B) and (C) further satisfy the following relationship.

Δλ_BC＝|Δλ_B-Δλ_C|≤0.19×10^-4

[ wherein, Delta lambda_BAnd delta lambda_CAre respectively represented by the following formula, wherein in the formula, lambda'_BAnd λ'_CRespectively shows birefringence values (I), (lambda) measured for the thermoplastic resin layers (B) and (C) in the resin laminate_BAnd lambda_CThe birefringence values (II) measured for the thermoplastic resin layers (B) and (C) in the resin laminate after annealing treatment at a temperature 25 ℃ lower than the Vicat softening temperature of the thermoplastic resin layers (B) and (C) for 4 hours, respectively, are shown.]

Δλ_B＝|λ’_B-λ_B|

Δλ_C＝|λ’_C-λ_C|

Lambda 'in the specification'_BAnd λ'_CThe birefringence value (I) measured for the thermoplastic resin layers (B) and (C) in the resin laminate is obtained by measuring the wave of the thermoplastic resin layer (B) or (C) in the resin laminate using an automatic birefringence meter (for example, "KOBRA-CCD" manufactured by Oerson instruments K.K.)A retardation (R) at 590nm in length and a birefringence value (λ) calculated from the obtained retardation by the following equation.

λ＝R/L

[ in the formula, λ represents a birefringence value, R represents a retardation at a wavelength of 590nm, and L represents a length (nm) of a short side of a sample for measuring a retardation. ]

Lambda in the present specification_BAnd lambda_CThe birefringence values (II) measured for the thermoplastic resin layers (B) and (C) in the resin laminate after annealing treatment at a temperature 25 ℃ lower than the vicat softening temperature of the thermoplastic resin layers (B) and (C) for 4 hours are: the retardation (R) at a wavelength of 590nm of the thermoplastic resin layer (B) or (C) is measured using the resin laminate after the annealing treatment using an automatic birefringence meter (for example, "KOBRA-CCD" manufactured by prince instruments), and the birefringence value (λ) is calculated from the obtained retardation using the following formula. The annealing treatment is a treatment of leaving the resin laminate at a temperature 25 ℃ lower than the vicat softening temperatures of the thermoplastic resin layers (B) and (C) for 4 hours, and when the vicat softening temperatures of the thermoplastic resin layers (B) and (C) are different from each other, the annealing treatment is performed at a temperature 25 ℃ lower than the higher vicat softening temperature.

λ＝R/L

In the embodiment of the present invention in which the thermoplastic resin layers (B) and (C) are (meth) acrylic resin layers, Δ λ is an aspect that the warpage of the resin laminate of the present invention is easily suppressed_BAnd delta lambda_CPreferably 0.16X 10^-4Hereinafter, more preferably 0.15 × 10^-4The following. In another embodiment of the present invention in which the thermoplastic resin layers (B) and (C) are polycarbonate resin layers, Δ λ is determined from the same viewpoint_BAnd delta lambda_CAre preferably 0.61X 10, respectively^-4Hereinafter, more preferably 0.60 × 10^-4The following. Delta lambda_BAnd delta lambda_CRespectively represent: the birefringence values (I) of the thermoplastic resin layers (B) and (C) in the resin laminate, and the annealing treatment of the resin laminateAnd the difference in birefringence values (II) of the thermoplastic resin layers (B) and (C) measured after eliminating the orientation intrinsic birefringence values generated during molding of the thermoplastic resin layers (B) and (C). When the difference is large, it means that the strain of the polymer arrangement of the resin generated when each layer is molded is large. Δ λ can be adjusted by adjusting the cooling rate at the time of production of the resin laminate_BAnd delta lambda_CAdjusted to the above range. In addition, Δ λ_BAnd delta lambda_CThe lower limit value is 0 because of its absolute value.

From the viewpoint of easily suppressing the warpage of the resin laminate of the present invention, Δ λ_BCPreferably 0.18X 10^-4The following. Delta lambda_BCThe absolute value is obtained by subtracting the difference between the birefringence value (II) and the birefringence value (I) of the thermoplastic resin layer (C) from the difference between the birefringence value (II) and the birefringence value (I) of the thermoplastic resin layer (B), and when the absolute value is large, it indicates that the difference in the degree of strain generated during molding processing is large between the thermoplastic resin layer (B) and the thermoplastic resin layer (C). The amount of the thermoplastic resin contained in the thermoplastic resin layers (B) and (C) can be adjusted to control the amount of the resin, the cooling rate, and the like_BCAdjusted to the above range. Delta lambda_BCThe lower limit value is 0 because of its absolute value.

It is considered that the thermoplastic resin layers (B) and (C) having a polymer arrangement strain within a specific range in the resin laminate are one of the causes of the resin laminate of the present invention being less likely to warp even when the resin laminate is used under conditions such as high temperature and high humidity.

ΔT＝|T_B-T_C|≤4℃

[ in the formula, T_BAnd T_CThe Vicat softening temperatures of the thermoplastic resin layers (B) and (C) are shown, respectively.]

From the viewpoint of easily suppressing the warpage of the resin laminate of the present invention, Δ T is preferably 3 ℃ or lower, more preferably 2 ℃ or lower, further preferably 1 ℃ or lower, and very preferably 0 ℃. Δ T represents the difference in vicat softening temperatures between the thermoplastic resin layers (B) and (C), and when this difference is large, it represents that the difference in the relaxation rates of strain is large. Δ T can be adjusted to be within the above range by adjusting the kind and composition of the resin contained in the thermoplastic resin layers (B) and (C). Here, the vicat softening temperature of the thermoplastic resin layer may be in accordance with JIS K7206: 1999 "Plastic-thermoplastic-Vicat Softening Temperature (VST) test method" by method B50. The Vicat softening temperature can be measured using a heat distortion tester (for example, 148-6 link model manufactured by Kabushiki Kaisha Anthemis Co., Ltd.). The measurement can be carried out using a test piece obtained by press molding each raw material to a thickness of 3 mm. Since Δ T is an absolute value, the lower limit value thereof is 0.

The thermoplastic resin layers (B) and (C) are preferably (meth) acrylic resin layers or polycarbonate resin layers from the viewpoint of good moldability and easy improvement in adhesion to the intermediate layer (a).

One embodiment of the present invention in which the thermoplastic resin layers (B) and (C) are (meth) acrylic resin layers will be described below. In this embodiment, the thermoplastic resin layers (B) and (C) contain 1 or more kinds of (meth) acrylic resins. From the viewpoint of surface hardness, the thermoplastic resin layers (B) and (C) contain preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more of a (meth) acrylic resin based on the total resin contained in each thermoplastic resin layer.

Examples of the (meth) acrylic resin include those described with respect to the (meth) acrylic resin contained in the intermediate layer (a). The preferable (meth) acrylic resin described for the intermediate layer (a) is also preferably the (meth) acrylic resin contained in the thermoplastic resin layers (B) and (C), unless otherwise specified. The (meth) acrylic resin contained in the thermoplastic resin layers (B) and (C) may be the same as or different from the (meth) acrylic resin contained in the intermediate layer (a).

The weight average molecular weight (Mw) of the (meth) acrylic resin is preferably 50,000 to 300,000, more preferably 70,000 to 250,000, from the viewpoint of good moldability and easy improvement of mechanical strength. The weight average molecular weight can be measured by Gel Permeation Chromatography (GPC) measurement.

In this embodiment, the thermoplastic resin layers (B) and (C) may further contain 1 or more kinds of thermoplastic resins other than the (meth) acrylic resin. As the thermoplastic resin other than the (meth) acrylic resin, a thermoplastic resin compatible with the (meth) acrylic resin is preferable. Specific examples thereof include a methyl methacrylate-styrene-maleic anhydride copolymer (for example, "RESISFY" manufactured by the electrochemical industry), a methyl methacrylate-methacrylic acid copolymer (for example, "ALTUMALHT 121" manufactured by Arkema), and a polycarbonate resin. As for the thermoplastic resin other than the (meth) acrylic resin, from the viewpoint of heat resistance, the resin composition is prepared in accordance with JIS K7206: 1999, preferably has a Vicat softening temperature of preferably 115 ℃ or higher, more preferably 117 ℃ or higher, and still more preferably 120 ℃ or higher. From the viewpoint of heat resistance and surface hardness, the thermoplastic resin layers (B) and (C) preferably contain substantially no vinylidene fluoride resin.

In this embodiment, the pencil hardness of the thermoplastic resin layers (B) and (C) is preferably HB or more, more preferably F or more, and even more preferably H or more, from the viewpoint of improving scratch resistance.

Next, another embodiment of the present invention in which the thermoplastic resin layers (B) and (C) are polycarbonate resin layers will be described below. In this embodiment, the thermoplastic resin layers (B) and (C) contain 1 or more kinds of polycarbonate resins. From the viewpoint of impact resistance, the thermoplastic resin layers (B) and (C) contain preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more of a polycarbonate resin based on the total resin contained in each thermoplastic resin layer.

Examples of the polycarbonate resin include polymers obtained by a phosgene method in which various dihydroxy diaryl compounds are reacted with phosgene, or a transesterification method in which a dihydroxy diaryl compound is reacted with a carbonate ester such as diphenyl carbonate, and specifically, a polycarbonate resin produced from 2, 2-bis (4-hydroxyphenyl) propane (generally referred to as bisphenol a).

Examples of the dihydroxydiaryl compound include bis (hydroxyaryl) alkanes such as bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane, 2-bis (4-hydroxyphenyl) butane, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2-bis (4-hydroxyphenyl-3-methylphenyl) propane, 1-bis (4-hydroxy-3-tert-butylphenyl) propane, 2-bis (4-hydroxy-3-bromophenyl) propane, 2-bis (4-hydroxy-3, 5-dibromophenyl) propane and 2, 2-bis (4-hydroxy-3, 5-dichlorophenyl) propane, in addition to bisphenol A, Bis (hydroxyaryl) cycloalkanes such as 1, 1-bis (4-hydroxyphenyl) cyclopentane and 1, 1-bis (4-hydroxyphenyl) cyclohexane, dihydroxydiaryl ethers such as 4, 4 '-dihydroxydiphenyl ether and 4, 4' -dihydroxy-3, 3 '-dimethyldiphenyl ether, dihydroxydiaryl sulfides such as 4, 4' -dihydroxydiphenyl sulfide, dihydroxydiaryl sulfoxides such as 4, 4 '-dihydroxydiphenyl sulfoxide and 4, 4' -dihydroxy-3, 3 '-dimethyldiphenyl sulfoxide, dihydroxydiaryl sulfones such as 4, 4' -dihydroxydiphenyl sulfone and 4, 4 '-dihydroxy-3, 3' -dimethyldiphenyl sulfone.

These can be used alone or in combination of 2 or more, and besides these, can also be mixed with piperazine, two piperidine group hydroquinone, resorcinol, 4' -two hydroxy biphenyl and use.

The dihydroxyaryl compound may be used in combination with a ternary or higher phenol compound as shown below. Examples of the trihydric or higher phenols include phloroglucinol, 4, 6-dimethyl-2, 4, 6-tris (4-hydroxyphenyl) -heptene, 2, 4, 6-dimethyl-2, 4, 6-tris (4-hydroxyphenyl) -heptane, 1, 3, 5-tris (4-hydroxyphenyl) -benzene, 1, 1, 1-tris (4-hydroxyphenyl) -ethane, and 2, 2-bis- [4, 4- (4, 4' -dihydroxydiphenyl) -cyclohexyl ] -propane.

Examples of the polycarbonate resin other than the above-mentioned polycarbonate resin include polycarbonates synthesized from isosorbide and an aromatic diol. An example of the polycarbonate is DURABIO (trademark registered) manufactured by Mitsubishi chemical corporation.

As the polycarbonate resin, commercially available products can be used, and examples thereof include "CALIBER (registered trademark) 301-4, 301-10, 301-15, 301-22, 301-30, 301-40, SD2221W, SD2201W, TR 2201" manufactured by Sumika Styron polycarbonate Limited.

In this embodiment, the weight average molecular weight (Mw) of the polycarbonate resin is preferably 20,000 to 70,000, more preferably 25,000 to 60,000, from the viewpoint of easily improving impact resistance and molding processability. The weight average molecular weight can be measured by Gel Permeation Chromatography (GPC) measurement.

In this embodiment, the polycarbonate resin contained in the thermoplastic resin layers (B) and (C) is preferably 3 to 120cm when measured at a temperature of 300 ℃ and a load of 1.2kg ³10 minutes, more preferably 3 to 80cm ³10 minutes, more preferably 4 to 40cm ³10 minutes, particularly preferably 10 to 40cm³Melt volume flow rate (hereinafter, also referred to as MVR.) of 10 minutes. When the MVR is higher than the above lower limit, the fluidity is sufficiently high, and molding processing is easy in melt coextrusion molding or the like, and poor appearance is less likely to occur, which is preferable. When the MVR is less than the above upper limit, mechanical properties such as strength of the polycarbonate resin layer are easily improved, and therefore, the MVR is preferable. MVR can be measured at 300 ℃ under a load of 1.2kg in accordance with JIS K7210.

In this embodiment, the thermoplastic resin layers (B) and (C) may further contain 1 or more kinds of thermoplastic resins other than the polycarbonate resin. As the thermoplastic resin other than the polycarbonate resin, a thermoplastic resin compatible with the polycarbonate resin is preferable, a (meth) acrylic resin is more preferable, and a methacrylic resin having an aromatic ring or a cycloolefin in the structure is further more preferable. When the thermoplastic resin layers (B) and (C) contain a polycarbonate resin and the above-mentioned (meth) acrylic resin, the surface hardness of the thermoplastic resin layers (B) and (C) can be further improved as compared with the case where only the polycarbonate resin is contained, and therefore, this is preferable.

At least 1 of the intermediate layer (a), the thermoplastic resin layers (B) and (C) in the resin laminate of the present invention may further contain various additives that are generally used within a range that does not impair the effects of the present invention. Examples of the additives include colorants such as stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, foaming agents, lubricants, mold release agents, antistatic agents, flame retardants, mold release agents, polymerization inhibitors, flame retardant aids, reinforcing agents, nucleating agents, and bluing agents.

Examples of the colorant include a compound having an anthraquinone skeleton, a compound having a phthalocyanine skeleton, and the like. Among these, compounds having an anthraquinone skeleton are preferable from the viewpoint of heat resistance.

When at least 1 of the intermediate layer (a), the thermoplastic resin layers (B) and (C) further contains a colorant, the content of the colorant in each layer can be appropriately selected depending on the purpose, the kind of the colorant, and the like. When a bluing agent is used as the colorant, the content thereof may be about 0.01 to 10ppm based on the total resin contained in each layer containing the bluing agent. The content thereof is preferably 0.01ppm or more, more preferably 0.05ppm or more, further more preferably 0.1ppm or more, and further preferably 7ppm or less, more preferably 5ppm or less, further more preferably 4ppm or less, and particularly preferably 3ppm or less. As the bluing agent, known bluing agents can be suitably used, and examples thereof include Macrolex (registered trademark) Blue RR (manufactured by Bayer), Macrolex (registered trademark) Blue 3R (manufactured by Bayer), Sumiplast (registered trademark) viloe B (manufactured by sumika chemtex Company, Limited), POLYSYNTHREN (registered trademark) Blue RLS (manufactured by Clariant), Diaresin Violet D, Diaresin Blue G, and Diaresin Blue N (manufactured by mitsubishi chemical corporation), which are trade names, respectively.

The ultraviolet absorber is not particularly limited, and various conventionally known ultraviolet absorbers can be used. Examples thereof include ultraviolet absorbers having a maximum absorption at 200 to 320nm or 320 to 400 nm. Specific examples thereof include triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzoate-based ultraviolet absorbers and cyanoacrylate-based ultraviolet absorbers. As the ultraviolet absorber, 1 kind of these ultraviolet absorbers may be used alone, or 2 or more kinds may be used in combination. From the viewpoint of more effectively protecting against damage caused by ultraviolet rays, it is also preferable to use at least 1 ultraviolet absorber having a maximum absorption at 200 to 320nm and at least 1 ultraviolet absorber having a maximum absorption at 320 to 400nm in combination. As the ultraviolet absorber, commercially available products can be used, and examples thereof include "Kemisorb 102" (2, 4-bis (2, 4-dimethylphenyl) -6- (2-hydroxy-4-N-octyloxyphenyl) -1, 3, 5-triazine manufactured by CHEMICPRO KASEI KAISHA, LTD.) (absorbance 0.1), "ADK STAB LA-F70" (2, 4, 6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1, 3, 5-triazine) (absorbance 0.6), "ADK STABLA-31, LA-31RG, LA-31G" (2, 2 '-methylenebis (4- (1, 1, 3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) (absorbance 0.2); "AdK STABLA RG, and" SACK-31G "(2, 2' -methylenebis (4- (1, 1, 3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) (absorbance 0.2) "ADK STAB LA-46" (2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- (2- (2-ethylhexanoyloxy) ethoxy) phenol, manufactured by ADEKA K.) (absorbance: 0.05) or "Tinuvin 1577" (2, 4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1, 3, 5-triazine) (absorbance: 0.1), manufactured by BASF Japan K. The absorbance of the exemplified ultraviolet absorber was the absorbance at 380 nm. The absorbance can be determined by: the ultraviolet absorber was dissolved in chloroform at a concentration of 10mg/L, and the concentration was measured using a spectrophotometer (e.g., spectrophotometer U-4100 manufactured by HITACHI).

When at least 1 of the intermediate layer (a), the thermoplastic resin layers (B) and (C) further contains an ultraviolet absorber, the content of the ultraviolet absorber in each layer can be appropriately selected depending on the purpose, the kind of the ultraviolet absorber, and the like. For example, the content of the ultraviolet absorber may be about 0.005 to 2.0 mass% based on the total resin contained in each layer containing the ultraviolet absorber. The content of the ultraviolet absorber is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and still more preferably 0.03% by mass or more. The content of the ultraviolet absorber is preferably 1.5% by mass or less, and more preferably 1.0% by mass or less. The content of the ultraviolet absorber is preferably not less than the above-described lower limit and not more than the above-described upper limit from the viewpoint of easily improving the ultraviolet absorption effect, and is therefore preferable because a change in the color tone (for example, the yellowness YI) of the resin laminate is easily prevented. Preferably, the above-mentioned amounts of "ADK STAB LA-31, LA-31RG and LA-31G" which are commercially available products are used.

In another embodiment of the present invention, the thermoplastic resin layers (B) and (C) are preferably polycarbonate resin layers, and when the ultraviolet absorber is contained in an amount of 0.005 to 2.0 mass% based on the total resin contained in each thermoplastic resin layer, a resin laminate having excellent light resistance is easily obtained.

In the resin laminate of the present invention, it is preferable that the average film thickness of the resin laminate is 100 to 2000 μm and the average film thicknesses of the thermoplastic resin layers (B) and (C) are 10 to 200 μm, respectively, from the viewpoint of easily suppressing warpage of the resin laminate of the present invention.

From the viewpoint of rigidity of the resin laminate, the average film thickness of the resin laminate of the present invention is preferably 100 μm or more, more preferably 200 μm or more, and still more preferably 300 μm or more. From the viewpoint of transparency, the thickness is preferably 2000 μm or less, more preferably 1500 μm or less, and still more preferably 1000 μm or less. The film thickness of the resin laminate can be measured by a digital micrometer (digital micrometer). The average value obtained by the above measurement at 10 points of the resin laminate was defined as the average value of the film thickness.

In the resin laminate of the present invention, the average film thicknesses of the thermoplastic resin layers (B) and (C) are each preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, from the viewpoint of facilitating improvement in surface hardness. From the viewpoint of dielectric constant, each of the thicknesses is preferably 200 μm or less, more preferably 175 μm or less, and still more preferably 150 μm or less. The average thickness of the thermoplastic resin layer was measured as described above.

In the resin laminate of the present invention, the average thickness of the intermediate layer (a) is preferably 100 μm or more, more preferably 200 μm or more, and still more preferably 300 μm or more, from the viewpoint of dielectric constant. From the viewpoint of transparency, the thickness is preferably 1500 μm or less, more preferably 1200 μm or less, and still more preferably 1000 μm or less. The average value of the film thickness of the intermediate layer (a) can be measured by the same method as the measurement of the average value of the film thickness of the thermoplastic resin layer.

The resin laminate of the present invention has a dielectric constant of preferably 3.5 or more, more preferably 4.0 or more, and still more preferably 4.1 or more, from the viewpoint of obtaining a function sufficient for use in a display device such as a touch panel. The upper limit of the dielectric constant is not particularly limited, and is usually 20. The dielectric constant can be adjusted to the above range by adjusting the kind and amount of the vinylidene fluoride resin contained in the intermediate layer (a) of the resin laminate of the present invention, or by adding a high dielectric constant compound such as ethylene carbonate, 1, 2-propylene carbonate, or the like. The dielectric constant is a value obtained in the following manner: according to JIS K6911: 1995, the resin laminate of the present invention was left to stand at 23 ℃ for 24 hours in an environment with a relative humidity of 50%, and measured at 3V and 100kHz by an auto-equilibrium bridge method in this environment. For the measurement, a commercially available machine can be used, and for example, "precision LCR meter HP 4284A" manufactured by Agilent Technologies Japan, Ltd.

The resin laminate of the present invention is preferably transparent when visually observed. Specifically, the resin laminate of the present invention has a total light transmittance (Tt) of preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more, as measured according to JIS K7361-1: 1997. The upper limit of the total light transmittance is 100%. Preferably, the resin laminate after exposure to an environment having a relative humidity of 90% at 60 ℃ for 120 hours has a total light transmittance within the above range.

The resin laminate of the present invention used in an environment at 60 ℃ and a relative humidity of 90% after exposure for 120 hours was subjected to a curing treatment in accordance with JIS K7136: when measured at 2000, the haze (haze value) is preferably 2.0% or less, more preferably 1.8% or less, and still more preferably 1.5% or less. In addition, the resin laminate of the present invention used in an environment at 60 ℃ and a relative humidity of 90% after exposure for 120 hours was subjected to a treatment in accordance with JIS Z8722: 2009, it has a yellowness (YellowIndex: YI value) of preferably 1.5 or less, more preferably 1.4 or less, still more preferably 1.3 or less. The resin laminate of the present invention having the above-described haze and yellowness is preferable in that warpage is less likely to occur even when used in an environment such as high temperature and high humidity, transparency is easily maintained, and yellowing is suppressed.

The resin laminate of the present invention may further have at least 1 functional layer in addition to the intermediate layer (a), the thermoplastic resin layers (B) and (C). The functional layer is preferably present on the surface of the thermoplastic resin layer (B) and/or (C) opposite to the intermediate layer (a). Examples of the functional layer include a hard coat layer, an antireflection layer, an antiglare layer, an antistatic layer, and an anti-fingerprint layer. These functional layers may be laminated on the resin laminate of the present invention via an adhesive layer, or may be coating layers laminated by coating. As the functional layer, for example, a cured film as described in japanese patent application laid-open No. 2013-86273 can be used. The functional layer may be a layer obtained by further applying an antireflection layer to one or both surfaces of at least 1 functional layer selected from the group consisting of a hard coat layer, an antiglare layer, an antistatic layer, and an anti-fingerprint layer by a coating method, a sputtering method, a vacuum deposition method, or the like, or a layer obtained by bonding an antireflection sheet to one or both surfaces of the at least 1 functional layer.

The thickness of the functional layer may be appropriately selected depending on the purpose of each functional layer, and is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more from the viewpoint of easily developing the function, and is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less from the viewpoint of easily preventing cracking of the functional layer.

The resin laminate of the present invention can be produced from the resin composition (a) providing the intermediate layer (a), and the resin compositions (B) and (C) providing the thermoplastic resin layers (B) and (C), respectively. In the present specification, the resin compositions (B) and (C) may include at least the resin providing the thermoplastic resin layers (B) and (C), and may include 2 or more components such as a resin and an optional additive, or may simply include 1 resin.

The resin composition (a) can be obtained by kneading a (meth) acrylic resin and a vinylidene fluoride resin. The kneading can be carried out, for example, by a method comprising a step of melt-kneading at a temperature of 150 to 350 ℃ and a shear rate of 10 to 1000/sec.

When the temperature at the time of melt kneading is 150 ℃ or higher, the resin can be sufficiently melted, and therefore, it is preferable that the temperature at the time of melt kneading is 350 ℃ or lower, because pyrolysis of the resin is easily suppressed. Further, when the shear rate is 10/sec or more at the time of melt kneading, it is easy to sufficiently knead the resin, and therefore, it is preferable that the shear rate is 1000/sec or less at the time of melt kneading, it is easy to suppress decomposition of the resin, and thus it is preferable.

In order to obtain a resin composition in which the respective components are more uniformly mixed, the melt kneading is carried out at a temperature of preferably 180 to 300 ℃, more preferably 200 to 300 ℃, and at a shear rate of preferably 20 to 700/sec, more preferably 30 to 500/sec.

As a machine for melt kneading, a usual mixer or kneader can be used. Specific examples thereof include a single-screw mixer, a twin-screw mixer, a multi-screw extruder, a Henschel mixer, a banbury mixer, a kneader, and a roll mixer. When the shear rate is increased within the above range, a high shear processing apparatus or the like may be used.

The resin compositions (B) and (C) can be produced by, for example, melt kneading at the above-mentioned temperature and shear rate in the same manner as the resin composition (a). For example, when the thermoplastic resin layers (B) and (C) include 1 thermoplastic resin, the resin laminate may be produced by melt extrusion described later without previously melt-kneading.

When the intermediate layer (a), the thermoplastic resin layers (B) and (C) contain an additive, the additive may be contained in the resin contained in each layer in advance, may be added at the time of melt-kneading of the resin, may be added after melt-kneading of the resin, or may be added at the time of producing a resin laminate using the resin composition.

The resin laminate of the present invention having at least the intermediate layer (a) and the thermoplastic resin layers (B) and (C) respectively present on both sides of the intermediate layer (a) can be produced by separately producing the respective layers (a) to (C) from the resin compositions (a) to (C) by, for example, melt extrusion molding, solution casting film forming method, hot press method, injection molding method, etc., and bonding them via, for example, an adhesive or an adhesive, or by integrally laminating the resin compositions (a) to (C) by melt coextrusion molding. In the case of producing a resin laminate by lamination, the layers are preferably produced by injection molding or melt extrusion molding, and more preferably by melt extrusion molding. The resin laminate of the present invention is preferably produced by melt coextrusion molding of the resin compositions (a) to (C), because a resin laminate which can be easily subjected to secondary molding can be usually obtained as compared with a resin laminate produced by lamination.

The melt coextrusion molding is, for example, the following molding method: the resin composition (a) and the resin compositions (B) and (C) are fed into 2 or 3 extruders each having a single screw or a twin screw, respectively, and melt-kneaded, and then the interlayer (a) formed of the resin composition (a) and the thermoplastic resin layers (B) and (C) are laminated and integrated via a feed head die, a multi-manifold die, and the like, and extruded. When the resin compositions (B) and (C) are the same, the thermoplastic resin layers (B) and (C) can be formed by equally dividing 1 part of the composition melt-kneaded in 1 extruder into 2 parts through a feed head die. The obtained resin laminate is preferably cooled and cured by, for example, a roller unit.

The resin laminate of the present invention can be cut out from the laminate produced as described above, and can be distributed in the form of a resin laminate having a size of, for example, 500 to 3000mm in width and 500 to 3000mm in length.

The resin laminate of the present invention can be used in various display devices. The display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic Electroluminescence (EL) display device, an inorganic Electroluminescence (EL) display device, a touch panel display device, an electron emission display device (e.g., an electric field emission display device (FED), a surface field emission display device (SED)), electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection display device (e.g., a Grating Light Valve (GLV) display device, a display device having a Digital Micromirror Device (DMD)), a piezoelectric ceramic display device, and the like. The liquid crystal display device includes any of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, a projection liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images or may be stereoscopic display devices that display three-dimensional images. The resin laminate of the present invention can be suitably used as, for example, a front panel or a transparent electrode in these display devices.

When the resin laminate of the present invention is used as a transparent electrode in a touch panel or the like, a transparent conductive sheet is produced by forming a transparent conductive film on at least one surface of the resin laminate of the present invention, and a transparent electrode is produced from the transparent conductive sheet.

As a method for forming a transparent conductive film on at least one surface of the resin laminate of the present invention, a transparent conductive film may be formed directly on the surface of the resin laminate of the present invention, or a plastic film on which a transparent conductive film is formed in advance may be laminated on the surface of the resin laminate of the present invention.

The film substrate of the plastic film on which the transparent conductive film is formed in advance is not particularly limited as long as it is a substrate capable of forming the transparent conductive film as a transparent film, and examples thereof include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, acrylic resin, polyamide, a mixture thereof, a laminate thereof, and the like. For the purpose of improving surface hardness, preventing newton's rings, imparting antistatic properties, and the like, the film may be coated in advance before forming the transparent conductive film.

The method of laminating a film on which a transparent conductive film is formed in advance on the surface of the resin laminate of the present invention may be any method as long as a uniform and transparent sheet free from bubbles or the like can be obtained. The lamination may be performed using an adhesive that is cured by room temperature, heat, ultraviolet light, or visible light, or may be performed using a transparent adhesive tape.

As a method for forming a transparent conductive film, a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, a spraying method, and the like are known, and these methods can be appropriately applied depending on a desired film thickness.

In the case of the sputtering method, for example, a normal sputtering method using an oxide target, a reactive sputtering method using a metal target, or the like can be used. In this case, oxygen, nitrogen, or the like may be introduced as the reactive gas, or ozone, plasma irradiation, ion assist, or the like may be added in combination. Further, a bias voltage such as a direct current, an alternating current, or a high frequency may be applied to the substrate as necessary. Examples of the transparent conductive metal oxide used for the transparent conductive film include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, indium-zinc composite oxide, and the like. Among these, indium-tin composite oxide (ITO) is preferable from the viewpoint of environmental stability and circuit processability.

As a method for forming a transparent conductive film, the following method can be applied: a method in which a coating agent containing various conductive polymers capable of forming a transparent conductive coating film is applied to the surface of the resin laminate of the present invention, and the coating layer is cured by ionizing radiation such as heat or ultraviolet irradiation; and so on. As the conductive polymer, polythiophene, polyaniline, polypyrrole, and the like are known, and these conductive polymers can be used.

The thickness of the transparent conductive film is not particularly limited, and when a transparent conductive metal oxide is used, it is usually the case

Preferably, it is

. When the amount is within the above range, both the conductivity and the transparency are excellent.

The thickness of the transparent conductive sheet is not particularly limited, and the most suitable thickness that meets the requirements of the product specifications of the display can be selected.

The resin laminate of the present invention can be used as a display panel, and a transparent conductive sheet produced from the resin laminate of the present invention can be used as a transparent electrode of a touch panel or the like to produce a touch sensor panel. Specifically, the resin laminate of the present invention can be used as a window sheet (window sheet) for a touch panel, and a transparent conductive sheet can be used as an electrode substrate for a touch panel of a resistive film type or a capacitive type. By disposing this touch panel on the front surface of a liquid crystal display device, an organic EL display device, or the like, an externally mounted touch sensor panel having a touch panel function can be obtained.

The present invention also provides a display device comprising the resin laminate of the present invention. The display device of the present invention may be, for example, the display device described above.

The present invention also provides a polarizing plate with a resin laminate obtained by laminating the resin laminate of the present invention and a polarizing plate, and a display device including the polarizing plate with a resin laminate. In the polarizing plate with a resin laminate of the present invention, the resin laminate of the present invention is laminated on the polarizing plate via an optical adhesive such as an adhesive or a pressure-sensitive adhesive. As the adhesive or the bonding agent, a known adhesive or bonding agent may be suitably used.

Fig. 2 schematically shows a preferred embodiment of a liquid crystal display device including the resin laminate of the present invention in a cross-sectional view. The resin laminate 10 of the present invention is laminated on a polarizing plate 11 via an optical adhesive layer 12, and the laminate can be disposed on the viewing side of a liquid crystal cell 13. Normally, the polarizing plate 11 is disposed on the back side of the liquid crystal cell 13. The liquid crystal display device 14 is constituted by such a member. Fig. 2 shows an example of a liquid crystal display device, and the display device of the present invention is not limited to this configuration.

Examples

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[ Vicat softening temperature ]

According to JIS K7206: 1999 "Plastic-thermoplastic-Vicat Softening Temperature (VST) test method" by the method B50. The Vicat softening temperature was measured by a heat distortion tester (148-6 continuous type manufactured by Kabushiki Kaisha Anta Seisakusho K.K.). The test piece was measured by press molding each raw material to a thickness of 3 mm.

[ content of alkali Metal ]

And (3) carrying out determination by using inductively coupled plasma mass spectrometry.

〔MFR〕

According to JIS K7210: 1999 "test methods for melt Mass Flow Rate (MFR) and melt volume flow Rate (MVR) of Plastic-thermoplastics". The poly (methyl methacrylate) -based material was measured under the conditions specified in JIS under the temperature of 230 ℃ and the load of 3.80kg (37.3N).

〔MVR〕

The polycarbonate-based resin material was measured under a load of 1.2kg at 300 ℃ using a Semi-Automatic Melt index measuring instrument 2A (Semi-Automatic Melt index tester 2A) manufactured by Toyo Seiki Seisaku-Sho, JIS K7210.

[ Total light transmittance and haze ]

According to JIS K7361-1: 1997 "test method for total light transmittance of plastic-transparent material-part 1: the single beam method "was carried out using a haze transmittance meter (" HR-100 "manufactured by COLOUR TECHNOLOGY, Inc. of Kyowa, Ltd.).

[ YI value ]

The measurement was carried out using a Spectrophotometer SQ2000 manufactured by Nippon Denshoku industries Co., Ltd.

[ average value of film thickness ]

The film thickness of the resin laminate was measured by a digital micrometer. The average value obtained by the above measurement at 10 points was defined as the average value of the film thickness of the resin laminate.

The film thicknesses of the respective layers of the intermediate layer (a), the thermoplastic resin layer (B), and the thermoplastic resin layer (C) were measured in the following manner: the resin laminate was cut perpendicularly to the plane direction, the cross section was ground with sandpaper, and then observed with a microscope made of Micro Square, inc. The average value obtained by the above measurement at 10 points was defined as the average value of the film thickness of each layer.

[ birefringent values (birefringent value I) of thermoplastic resin layers (B) and (C) in the resin laminate ]

The resin laminate was cut in a direction perpendicular to the lamination surface to obtain a rectangular parallelepiped having a size of 8mm in the short side and the long side of 600 μm on the thermoplastic resin layer surface and a thickness equal to the film thickness of the resin laminate. The plate was fixed to glass so that the cross section thereof was oriented upward, to obtain a phase difference measurement sample. The fixation is performed using an epoxy-based adhesive. The obtained sample was set in an automatic birefringence meter ("KOBRA-CCD" manufactured by prince measurement corporation) so that the layer to be measured faced the incident side of the measurement light, and the retardation (R) at a wavelength of 590nm was measured under the conditions of a temperature of 23 ± 2 ℃ and a humidity of 50 ± 5%. Using the obtained phase difference, the birefringence value (λ) was calculated from the following equation. The birefringence value calculated as described above is referred to as birefringence value (I).

λ＝R/L

[ in the formula, λ represents a birefringence value, R represents a retardation, and L represents a length (nm) of a short side of a sample for measuring a retardation. ]

[ birefringence values (birefringence values II) of the thermoplastic resin layers (B) and (C) in the resin laminate after annealing treatment at a temperature 25 ℃ lower than the Vicat softening temperature of the thermoplastic resin layers (B) and (C) for 4 hours ]

In order to eliminate the influence of strain at the time of molding, the resin laminate was placed in an oven set to a temperature 25 ℃ lower than the vicat softening temperature of the thermoplastic resin layers (B) and (C) for 4 hours, and subjected to annealing treatment to obtain a resin laminate for measuring birefringence value (II) from which strain at the time of molding was removed. Using the obtained resin laminate, the retardation was measured by the same method as the measurement of the birefringence value (I), and the birefringence value was calculated by substituting the measured retardation into the above formula. The birefringence value calculated as described above is referred to as birefringence value (II). When the vicat softening temperatures of the thermoplastic resin layers (B) and (C) are different from each other, the annealing treatment is performed at a temperature 25 ℃ lower than the higher vicat softening temperature.

[ evaluation of warpage ]

The resulting sheet-like resin laminate was cut into a size of 100X 56mm to prepare a sample for warpage evaluation. The sample was left to stand in a constant temperature and humidity apparatus at a temperature of 60 ℃ and a relative humidity of 90% for 120 hours, and the change in warpage before and after the standing was evaluated. The evaluation was carried out as follows: the sample was observed at 4 ends with a high-precision CCD micrometer manufactured by Keyence Corporation, and the height of the generated warpage was measured to calculate the average value of the heights of the 4 ends.

[ production example 1]

97.7 parts by mass of methyl methacrylate and 2.3 parts by mass of methyl acrylate were mixed, and 0.05 part by mass of a chain transfer agent (octyl mercaptan) and 0.1 part by mass of a release agent (stearyl alcohol) were added to obtain a monomer mixture. Further, 0.036 part by mass of a polymerization initiator [1, 1-bis (t-butylperoxy) -3, 3, 5-trimethylcyclohexane ] was added to 100 parts by mass of methyl methacrylate to obtain an initiator mixture. The monomer mixture and the initiator mixture were continuously supplied to a complete mixing type polymerization reactor so that the flow ratio of the monomer mixture to the initiator mixture became 8.8: 1, and the mixture was polymerized under the conditions of an average residence time of 20 minutes and a temperature of 175 ℃ until the average polymerization rate became 54%, to obtain a partial polymer. The obtained partial polymer was heated to 200 ℃ and introduced into a devolatilizing extruder with a vent, unreacted monomers were devolatilized from the vent at 240 ℃, and the devolatilized polymer was extruded in a molten state, cooled with water, and cut to obtain a granular methacrylic resin (i).

The obtained granular methacrylic resin composition was analyzed by pyrolysis gas chromatography under the conditions shown below, and the respective peak areas corresponding to methyl methacrylate and acrylic ester were measured. As a result, in the methacrylic resin (i), the structural unit derived from methyl methacrylate was 97.0 mass%, and the structural unit derived from methyl acrylate was 3.0 mass%.

[ content of structural units by pyrolysis gas chromatography ]

(pyrolysis conditions)

Sample preparation: the methacrylic resin composition was precisely weighed (target amount was 2 to 3mg), and put into the center of a cylindrical metal chamber (cell), the metal chamber was closed, and both ends were lightly pressed with a pincer to perform sealing.

A pyrolysis device: CURIE POINT PYROLYZER JHP-22 (manufactured by JAN ANALYSIS INDUSTRIAL CO., LTD.)

A metal chamber: pyrofoil F590 (manufactured by Nippon analytical industries Co., Ltd.)

Set temperature of thermostatic bath: 200 deg.C

Setting temperature of the heat preservation pipe: 250 deg.C

Pyrolysis temperature: 590 deg.C

Pyrolysis time: 5 seconds

(gas chromatography conditions)

Gas chromatography analysis apparatus: GC-14B (manufactured by Shimadzu Kaisha)

The detection method comprises the following steps: FID

Column: 7G 3.2 m.times.3.1 mm phi (manufactured by Shimadzu corporation)

Filling agent: FAL-M (manufactured by Shimadzu Kaisha)

Carrier gas: air/N2/H2 ═ 50/100/50(kPa), 80 ml/min

Temperature rise conditions of the column: maintaining at 100 deg.C for 15 min, heating to 150 deg.C at a rate of 10 deg.C/min, and maintaining at 150 deg.C for 14 min

INJ temperature: 200 deg.C

DET temperature: 200 deg.C

The methacrylic resin composition was pyrolyzed under the pyrolysis conditions, the decomposition product generated was measured under the gas chromatography conditions, and the peak area (a1) corresponding to the methyl methacrylate and the peak area (b1) corresponding to the acrylic ester detected at that time were measured. Then, from these peak areas, a peak area ratio a (═ b1/a1) was determined. On the other hand, the weight ratio of the acrylate ester unit to the methyl methacrylate unit is W under the above pyrolysis conditions₀(known) a standard of a methacrylic resin was pyrolyzed, the decomposition product produced was measured under the above-mentioned gas chromatography conditions, and the peak area (a) corresponding to the methyl methacrylate detected at that time was measured₀) And the peak area corresponding to the acrylate (b)₀) The peak area ratio A was determined from these peak areas₀(＝b₀/a₀). Then, the peak area ratio A is determined from the above₀And the aforementioned weight ratio W₀The coefficient f (═ W) is obtained₀/A₀)。

The peak area ratio a is multiplied by the coefficient f to obtain a weight ratio W of the acrylate ester unit to the methyl methacrylate unit in the copolymer contained in the methacrylic resin composition, and from the weight ratio W, a ratio (mass%) of the methyl methacrylate unit to the total of the methyl methacrylate unit and the acrylate ester unit and a ratio (mass%) of the acrylate ester unit to the total of the methyl methacrylate unit and the acrylate ester unit are calculated.

[ production example 2]

A granular methacrylic resin (ii) was obtained in the same manner as in production example 1 except that the amount of methyl methacrylate was changed to 98.9 parts by mass, the amount of methyl acrylate was changed to 1.1 parts by mass, and the amount of the structural unit was measured, and the amount of the chain transfer agent was changed to 0.16 part by mass. In the methacrylic resin (ii), the structural unit derived from methyl methacrylate was 97.5 mass%, and the structural unit derived from methyl acrylate was 2.5 mass%.

[ production example 3]

Acrylic rubber particles having a spherical 3-layer structure and an average particle diameter of 0.22 μm were produced in accordance with example 3 of Japanese patent publication No. 55-27576 and used as the acrylic rubber particles (i). The acrylic rubber particles (i) have: an innermost layer which is a hard polymer obtained by polymerization using methyl methacrylate and a small amount of allyl methacrylate; an intermediate layer which is an elastic polymer obtained by polymerizing butyl acrylate as a main component and further using styrene and a small amount of allyl methacrylate; and an outermost layer which is a hard polymer obtained by polymerization using methyl methacrylate and a small amount of methyl acrylate. The average particle diameter of the acrylic rubber particles (i) is determined by mixing the acrylic rubber particles with a methacrylic resin to form a film, dyeing the elastic polymer (intermediate layer) with ruthenium oxide on the cross section of the film, observing the dyed portion with an electron microscope, and measuring the diameter of the dyed portion.

65 parts of pellets of the methacrylic resin (i) and 35 parts of the acrylic rubber particles (i) were mixed in a super mixer, and melt-kneaded in a twin-screw extruder to prepare pellets.

The physical properties of the methacrylic resins (i) to (iii) obtained in production examples 1 to 3 are shown in Table 1.

[ Table 1]

[ production example 4]

In order to form the bluing agent into a Master Batch (MB), 99.99 parts by weight of the methacrylic resin (i) obtained in production example 1 and 0.01 part by weight of the colorant were dry-blended, and melt-mixed at a set temperature of 250 to 260 ℃ by a 40mm phi single screw extruder (manufactured by Takeda plastic mechanical Co., Ltd.) to obtain colored master batch particles (MB (i)). As the colorant, bluing agent ("Sumiplast (trademark registration) Violet B" manufactured by ltd., Sumika Chemtex co., ltd.) was used.

In examples and comparative examples, commercially available vinylidene fluoride resins having physical properties shown in table 2 were used.

Vinylidene fluoride resin (i): polyvinylidene fluoride produced by suspension polymerization

Vinylidene fluoride resin (ii): polyvinylidene fluoride produced by emulsion polymerization

[ Table 2]

The weight average molecular weight (Mw) of the vinylidene fluoride resin was measured by Gel Permeation Chromatography (GPC). The weight average molecular weight of each resin was determined by preparing a calibration curve from the elution time and the molecular weight using polystyrene as a standard reagent. Specifically, 40mg of the resin was dissolved in 20ml of an N-methylpyrrolidone (NMP) solvent to prepare a measurement sample. As the measuring apparatus, the following apparatus was used: 2 columns "TSKgel SuperHM-H" made by TOSOHCORPORATION and 1 column "SuperH 2500" were arranged in series, and an RI detector was used as the detector.

In examples and comparative examples, commercially available products shown below were used as polycarbonate resins. The physical properties of the resin are shown in Table 3.

Polycarbonate resin (i): "CALIBRA (registered trademark) 301-30" manufactured by Sumika Styron Polycarbonate Limited "

[ Table 3]

The weight average molecular weight of the polycarbonate resin was measured by GPC. A calibration curve was prepared from the elution time and the molecular weight using a methacrylic resin having a narrow molecular weight distribution and a known molecular weight, manufactured by Showa Denko K.K., as a standard reagent, and the weight average molecular weight was measured. Specifically, 40mg of the resin was dissolved in 20ml of Tetrahydrofuran (THF) solvent to prepare a measurement sample. As the measuring apparatus, the following apparatus was used: 2 columns "TSKgel SuperHM-H" made by TOSOHCORPORATION and 1 column "SuperH 2500" were arranged in series, and an RI detector was used as the detector.

[ production of resin laminates according to examples 1 to 3 and comparative examples 1 to 6]

The methacrylic resin and the vinylidene fluoride resin shown in tables 1 and 2 and the master batch pellets mb (i) obtained in production example 4 were mixed at the ratio shown in table 4 to obtain a resin composition (a) for forming the intermediate layer (a). As the resin compositions (B) and (C) for forming the thermoplastic resin layers (B) and (C), methacrylic resins shown in table 1, the mixtures obtained in production example 3, or polycarbonate resins shown in table 3 were used. Using the apparatus shown in fig. 1, a resin laminate was produced from these resin compositions. Specifically, the resin composition (A) was melted by a 65mm phi single screw extruder 2 (manufactured by Toshiba mechanical Co., Ltd.), and the resin compositions (B) and (C) were melted by 45mm phi single screw extruders 1 and 3 (manufactured by Hitachi Kayak Co., Ltd.). Then, they were supplied to a 3-type 3-layer distribution type feed head 4 having a set temperature of 230 to 270 ℃ and distributed so as to have a 3-layer structure, and then extruded from a manifold-type die 5 (manufactured by hitachi ship corporation, distributed in 2 types of 3-layer) so as to be laminated so as to have a structure represented by B layer/a layer/C layer, thereby obtaining a film-shaped molten resin 6. The obtained molten resin 6 in the form of a film was sandwiched between a1 st cooling roll 7 (having a diameter of 350mm) and a2 nd cooling roll 8 (having a diameter of 450mm) which were disposed so as to face each other, and then sandwiched between the 2 nd roll 8 and a 3 rd roll 9 (having a diameter of 350mm) while being wound around the 2 nd roll 8, and then wound around the 3 rd cooling roll 9 to be molded and cooled, thereby obtaining a resin laminate 10 having a 3-layer structure in which each layer had an average value of the film thicknesses shown in table 4. The obtained resin laminates 10 each had a total film thickness of about 800 μm, and were colorless and transparent as a result of visual observation.

[ Table 4]

Table 5 shows the temperature and drawing speed of each cooling roll in the production of the resin laminate, and the discharged resin temperature obtained by measuring the resin discharged from the die with a non-contact thermometer.

[ Table 5]

Regarding the thermoplastic resin layers (B) and (C) of the resin laminates of examples 1 to 3 and comparative examples 1 to 5, Δ L and Δ λ were measured_B、Δλ_C，Δλ_BCAnd Δ T are shown in table 6 below.

[ Table 6]

In the resin laminates of examples 1 to 3 and comparative examples 1 to 5, the content of alkali metals (Na and K) in the intermediate layer (a) was 0.3ppm in examples 1 and 2 and comparative examples 1 to 5, and 100ppm in example 3.

The dielectric constants of the resin laminates of examples 1 to 3 and comparative examples 1 to 5 were 5.2 in example 1 and comparative examples 2, 3 and 5, 5.3 in example 2, 5.1 in comparative examples 1 and 4, and 4.9 in example 3. It was confirmed that all of the resin laminates had a dielectric constant sufficient for use in display devices such as touch panels.

The resin laminates of examples 1 to 3 and comparative examples 1 to 5 were used to evaluate the total light transmittance (Tt), Haze (Haze) and warpage. The obtained results are shown in table 7. The resin laminates of examples 1 to 3 and comparative examples 1 to 5 were exposed to 60 ℃ for 120 hours in an environment with a relative humidity of 90%, and warpage was evaluated in the same manner for the resin laminates after the durability test. The results after the durability test are also shown in Table 7.

[ Table 7]

It is clear that the resin laminates of the present invention shown in examples 1 to 3 have not only high transparency but also less warpage. Furthermore, the resin laminates of the present invention shown in examples 1 to 3 were less likely to warp even after the durability test under high-temperature and high-humidity conditions.

Description of the reference numerals

1 Single screw extruder (extruding the melt of resin composition B)

2 Single screw extruder (extruding the melt of resin composition A)

3 Single screw extruder (extruding the melt of resin composition C)

4 feed head

5 multi-manifold die head

6 film-like molten resin

7 st 1 Cooling roll

8 nd 2 cooling roller

9 rd 3 chill roll

10 resin laminate

10A intermediate layer (A)

10B thermoplastic resin layer (B)

10C thermoplastic resin layer (C)

11 polarizing plate

12 optical bonding layer

13 liquid crystal cell

14 liquid crystal display device

Claims

1. A resin laminate obtained by melt coextrusion molding and having at least an intermediate layer (A) and thermoplastic resin layers (B) and (C) present on both sides of the intermediate layer (A), wherein,

the thermoplastic resin layers (B) and (C) satisfy the following relationship,

[ mathematical formula 1]

5μm≤ΔL＝|L_B-L_C|≤20μm

[ mathematical formula 2]

Δλ_BC＝|Δλ_B-Δλ_C|≤0.19×10^-4

[ mathematical formula 3]

ΔT＝|T_B-T_C|≤4℃

In the formula, L_BAnd L_CRespectively, the average film thicknesses of the thermoplastic resin layers (B) and (C),

Δλ_Bis represented by the following formula (I),

[ mathematical formula 4]

Δλ_B＝|λ’_B-λ_B|

Δλ_CIs represented by the following formula (I),

[ math figure 5]

Δλ_C＝|λ’_C-λ_C|

λ’_BAnd λ'_CRespectively shows birefringence values (I), (lambda) measured for the thermoplastic resin layers (B) and (C) in the resin laminate_BAnd lambda_CRespectively shows birefringence values (II), T, measured for the thermoplastic resin layers (B) and (C) in the resin laminate after annealing treatment at a temperature 25 ℃ lower than the Vicat softening temperature of the thermoplastic resin layers (B) and (C) for 4 hours_BAnd T_CThe Vicat softening temperatures of the thermoplastic resin layers (B) and (C) are shown, respectively.

2. The resin laminate according to claim 1, wherein the intermediate layer (A) comprises 35 to 45 mass% of a (meth) acrylic resin and 65 to 55 mass% of a vinylidene fluoride resin based on the total resins contained in the intermediate layer (A).

3. The resin laminate according to claim 1 or 2, wherein the content of the alkali metal in the intermediate layer (a) is 50ppm or less based on the total resin contained in the intermediate layer (a).

4. The resin laminate according to claim 1 or 2, wherein the (meth) acrylic resin is:

(a1) homopolymers of methyl methacrylate; and/or

(a2) A copolymer comprising 50 to 99.9 mass% of a structural unit derived from methyl methacrylate and 0.1 to 50 mass% of at least 1 structural unit derived from a (meth) acrylate represented by the formula (1) based on the total structural units constituting the polymer,

[ chemical formula 1]

In the formula, R₁Represents a hydrogen atom or a methyl group, R₁When it is a hydrogen atom, R₂Represents an alkyl group having 1 to 8 carbon atoms, R₁When it is methyl, R₂Represents an alkyl group having 2 to 8 carbon atoms.

5. The resin laminate according to claim 1 or 2, wherein the vinylidene fluoride resin is polyvinylidene fluoride.

6. The resin laminate according to claim 1 or 2, wherein the vinylidene fluoride resin has a melt mass flow rate of 0.1 to 40g/10 min as measured under a load of 3.8kg and at 230 ℃.

7. The resin laminate according to claim 1 or 2, wherein the average thickness of the resin laminate is 100 to 2000 μm, and the average thickness of the thermoplastic resin layers (B) and (C) is 10 to 200 μm.

8. The resin laminate according to claim 1 or 2, wherein the vicat softening temperatures of the thermoplastic resins contained in the thermoplastic resin layers (B) and (C) are 100 to 160 ℃.

9. The resin laminate according to claim 1 or 2, wherein the thermoplastic resin layers (B) and (C) are (meth) acrylic resin layers or polycarbonate resin layers.

10. The resin laminate according to claim 1 or 2, wherein the thermoplastic resin layers (B) and (C) are polycarbonate resin layers, and each of the thermoplastic resin layers contains 0.005 to 2.0 mass% of an ultraviolet absorber based on the total resin contained in the thermoplastic resin layer.

11. The resin laminate according to claim 1 or 2, wherein the thermoplastic resin layers (B) and (C) comprise 50% by mass or more of a (meth) acrylic resin based on the total resin contained in each thermoplastic resin layer.

12. The resin laminate according to claim 11, wherein the weight average molecular weight of the (meth) acrylic resin contained in the thermoplastic resin layers (B) and (C) is 50,000 to 300,000.

13. A display device comprising the resin laminate according to any one of claims 1 to 12.

14. A polarizing plate with a resin laminate, which is obtained by laminating the resin laminate according to any one of claims 1 to 12 and a polarizing plate.

15. A display device comprising the polarizing plate with a resin laminate according to claim 14.