JPH08211379A - Laminated body for liquid crystal display - Google Patents

Abstract

PURPOSE: To provide a laminated body for a liquid crystal display in which one of a polarizing plate film, phase difference plate film and laminated sheet of a polarizing plate film and phase difference film is firmly adhered to a glass cell for a liquid crystal display without peeling from the glass cell even under conditions of high temp. and high humidity and bad influence is hardly given to wirings for the liquid crystal. CONSTITUTION: A glass cell for a liquid crystal display has a three-layer structure comprising a glass having <5mol% alkali metal content in the glass, a glass having >=5mol% alkali metal content, and an adhesive layer between these glasses. An acryl adhesive and a film for a liquid crystal display are successively deposited on the glass surface side of the glass cell to constitute a laminated body for a liquid crystal display. This film for a liquid crystal display is one of a polarizing plate film, phase difference plate film and laminated sheet of a polarizing plate film and phase difference plate film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a polarizing plate film, retardation film,
Alternatively, the present invention relates to a liquid crystal display laminate in which any one of a laminate of a polarizing plate film and a retardation film is laminated.

[0002]

2. Description of the Related Art As a liquid crystal display panel for display,
It is common that a polarizing plate film or a retardation film is laminated on an alkali glass cell for liquid crystal display via an adhesive layer or an adhesive layer. When left to stand, the pressure-sensitive adhesive layer and the alkalinity layer may be changed due to the accumulation of deformation stress due to the heat shrinkage of the polarizing plate film or the retardation film, or the intrusion of water into the interface between the pressure-sensitive adhesive and the alkali glass cell for liquid crystal display. There is a problem that peeling is likely to occur at the interface of the glass cell.

In order to solve the above problems, the pressure-sensitive adhesive used has been improved. For example, by adding a silane compound having an epoxy group to an acrylic pressure-sensitive adhesive in advance, good adhesion to glass can be obtained. Acrylic pressure sensitive adhesives are disclosed (Japanese Patent Laid-Open No. 4-223403).

However, the above-mentioned JP-A-4-22340.
The acrylic pressure-sensitive adhesive of Japanese Patent No. 3 has a problem that the silane compound in the pressure-sensitive adhesive has poor stability over time and the adhesive strength changes over time.

To solve the above problems, for example, there is a method of increasing the alkali metal concentration in the glass to improve the wettability of the glass surface.

[0006]

However, in the above method, the alkali metal ions such as sodium ions existing on the surface of the glass cell are formed of indium oxide or the like which is in contact with the side opposite to the surface on which the adhesive is laminated. Since it is unevenly distributed in the liquid crystal wiring and permeates and partially reduces the resistance value, the amount of current passing through the liquid crystal wiring is different, which causes a new problem of an unclear screen.

It is an object of the present invention that either the polarizing plate film, the retardation film or the laminated sheet of the polarizing film and the retardation film is peeled from the glass cell for liquid crystal display even under high temperature and high humidity conditions. It is to provide a laminated body for liquid crystal display, which is firmly adhered without any damage, and has little adverse effect on liquid crystal wiring even when used as a liquid crystal display body.

[0008]

The glass cell for liquid crystal display used in the present invention comprises (A) a glass having an alkali metal content of less than 5 mol% and (B) an alkali metal content of 5 mol% or more. It has a three-layer structure in which glass is laminated via an adhesive layer.

By using the glass (A) having an alkali metal content of less than 5 mol% (hereinafter referred to as "glass A"), adverse effects on the liquid crystal wiring can be reduced. The glass A is a method of preliminarily eluting the alkali metal in the vicinity of the glass cell surface by treating the ordinary glass surface with a hydrosilicofluoric acid solution, or by eluting the alkali metal with sodium, which is easy to elute. It can be obtained by a method of substituting difficult potassium or titanium.

For glass (B) having an alkali metal content of 5 mol% or more (hereinafter referred to as "glass B"), a pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer provided on a polarizing plate film or a retardation film is attached. Even when attached, sufficient adhesive strength can be obtained, and even when left under high temperature and high humidity conditions,
It is used to reduce problems such as foaming and peeling. As such a glass, for example, a general glass generally known as "soda glass" can be mentioned.

The adhesive used to bond the two glasses A and B together does not impair the optical properties such as the transparency of the glass cell and firmly bonds the two glasses even under high temperature and high humidity conditions. It requires heat resistance or moisture resistance, and includes acrylic adhesives, epoxy adhesives, silicone adhesives, etc. Among them, epoxy adhesives are preferred because of their high adhesiveness and weather resistance. Adhesives are preferably used.

In the acrylic adhesive, the trade name "Olivine BPS-4940" (manufactured by Toyo Ink Co., Ltd.) is used. In the epoxy adhesive, the trade name is "Epicoat #".
828 "(manufactured by Yukacel Epoxy Co., Ltd.) and a highly transparent mixture such as triethylenetetramine. In the above silicone-based adhesive, a trade name" YR-3286 "(manufactured by Toshiba Silicone Co., Ltd.) and the like can be mentioned. .

The thickness of the adhesive layer between the two sheets of glass is
If the thickness is reduced, the adhesive force may be reduced and peeling may occur between the two sheets of glass, and if the thickness is increased, the light transmittance may be reduced and the screen of the liquid crystal display device may be darkened.
It is 0 μm, more preferably 1.0 to 5 μm.

If desired, a silane coupling agent may be added to the above-mentioned adhesive used in the present invention for the purpose of improving the adhesion to glass. For example, trade name "SH6040" (Chisso (Manufactured by the company) and the like are commercially available.

In the liquid crystal display laminate of the present invention, the acrylic adhesive and the liquid crystal display film are sequentially laminated on the glass B surface of the glass cell obtained by the above-mentioned method.

The above acrylic pressure-sensitive adhesive does not impair the optical properties such as transparency as a laminate for liquid crystal displays, and can be used as a polarizing plate film, a retardation film, or a polarizing film and a retardation film even under high temperature and high humidity conditions. A method for firmly adhering a laminated sheet of a film to a glass cell, having sufficient weather resistance,
In terms of obtaining heat resistance or humidity resistance, for example,
It is preferable that the main component is a high molecular weight acrylic polymer having a weight average molecular weight of 800,000 or more.

Examples of the acrylic polymer include those obtained by copolymerizing an alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms and a vinyl monomer having a polar group.

Examples of the alkyl (meth) acrylate include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, Isononyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate,
Stearyl (meth) acrylate etc. are mentioned.

When the content of the alkyl (meth) acrylate is small, the cohesive force is high and it is difficult to obtain sufficient pressure-sensitive adhesiveness, and when it is large, the cohesive force is low and it is difficult to obtain sufficient shear strength. The total amount of constituent monomers is preferably 50 to 98% by weight, more preferably 70 to 95% by weight.

Examples of the vinyl monomer having a polar group include (meth) acrylic acid, itaconic acid, crotonic acid, (anhydrous) maleic acid, (anhydrous) fumaric acid, and carboxyalkyl (meth) acrylates such as carboxyethyl acrylate. Carboxyl group-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, 2
-Hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone modified (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth)
In addition to vinyl monomers having a hydroxyl group such as acrylate, (meth) acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyllaurylolactam, (meth) acryloylmorpholine, (meth) acrylamide, dimethyl (meth) acrylamide , N-
Methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl ( Examples thereof include nitrogen-containing vinyl monomers such as (meth) acrylate.

Vinyl monomers such as vinyl acetate, vinyl pivalate, vinyl propionate, styrene and isobornyl (meth) acrylate may be copolymerized in the acrylic polymer.

When the content of the vinyl monomer having the above polar group and the content of the other vinyl monomer are small, the cohesive force is low and it is difficult to obtain sufficient shear strength, and when the content is large, the cohesive force is high and the pressure-sensitive adhesive property is sufficient. Since it is difficult to obtain, 2 to 50% by weight is preferable in the total amount of constituent monomers.
And preferably 5 to 30% by weight.

As the method for obtaining the above acrylic polymer, solvent polymerization is preferable from the viewpoint of easy control of the polymerization reaction, and in that case, a thermal polymerization initiator is generally used.

Examples of the thermal polymerization initiator include ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, isobutyryl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and the like. Diacyl peroxides such as P-chlorobenzoyl peroxide, hydroperoxides such as diisopropylbenzene hydroperoxide and t-butyl hydroperoxide, 2,5
-Dialkyl peroxides such as dimethyl-2,5-di- (t-butylperoxy) hexane, 1,3-bis- (t-butylperoxyisopropyl) benzene and di-t-butylperoxide, 1, Peroxyketals such as 1-di-t- (butylperoxy) -3,3,5-trimethylcyclohexane and 1,1-di- (t-butylperoxy) cyclohexane, t-butylperoxypivalate, Alkyl peresters such as t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, di-2-ethylhexylperoxydicarbonate, bis- (4-t-butylcyclohexyl) peroxy In addition to organic peroxides such as percarbonates such as dicarbonates, 2,2′-azobis-isobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azo Examples thereof include azobis compounds such as bisisobutyrate, 4,4′-azobis-4-cyanovaleric acid, and 2,2′-azobis- (2-aminopropane) dihydrochloride.

A chain transfer agent may be added for the purpose of suppressing variations in the polymerization reaction when polymerizing the acrylic polymer and appropriately controlling the molecular weight of the resulting copolymer.
For example, n-dodecyl mercaptan, 2-mercaptoethanol, β-mercaptopropionic acid, octyl β-mercaptopropionate, methoxybutyl β-mercaptopropionate, trimethylolpropane tris (β-
Thiopropionate), butyl thioglycolate, propanethiols, butanethiols, thiophosphites and other thiol compounds, and carbon tetrachloride and other halogen compounds.

The acrylic polymer obtained by the above-mentioned method may be cross-linked with a cross-linking agent, and the cross-linking agent is capable of reacting with a polar group in a copolymer as used in general solvent-type pressure-sensitive adhesives. All of these can be used, for example, tolylene diisocyanate (TDI), naphthylene-1,5-diisocyanate, diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate. (IPD
I), xylene diisocyanate (XDI), trimethylolpropane modified TDI, etc., isocyanate type crosslinking agent, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, etc. , N, N-hexamethylene-1,6-bis (1-aziridinecarboxamide) and the like.

The acrylic adhesive used in the present invention is
Although the above-mentioned acrylic polymer is the main component, a tackifier resin or the like may be added, if necessary, within a range that does not impair optical characteristics such as transparency.

Examples of the tackifying resin include C5
-Based and C9-based petroleum resin, rosin resin, rosin ester resin, terpene resin, terpene phenol resin, coumarone indene resin, disproportionated rosin resin, disproportionated rosin ester resin, polymerized rosin resin, polymerized rosin ester resin,
Examples thereof include xylene resin, styrene resin, and hydrogenated products thereof, and these may be used alone or in combination of two or more kinds.

Since the above tackifying resin becomes an uncrosslinked component in the acrylic pressure-sensitive adhesive, the cohesive force becomes low when the addition amount is large, and it becomes difficult to obtain sufficient shear strength.
The addition amount is 30 with respect to 100 parts by weight of the acrylic polymer.
It is preferably less than or equal to parts by weight.

When the thickness of the acrylic pressure-sensitive adhesive layer becomes thin, the adhesive force between the polarizing plate film or retardation film and the glass cell decreases, so that the polarizing plate film or retardation plate under high temperature and high humidity conditions. Interfacial fracture is likely to occur due to stress at the time of heat shrinkage of the film, and when it becomes thick, the residual solvent in the acrylic pressure-sensitive adhesive increases, and foaming occurs under high temperature conditions. Therefore, it is preferably 5 to 40 μm, more preferably 10 μm. ˜30 μm.

The liquid crystal display film is either a polarizing plate film, a retardation film, or a laminated sheet of a polarizing plate film and a retardation film. Particularly, in the case of the above laminated sheet, a retardation film It is preferably laminated on the glass cell for a liquid crystal display so that the surface is in contact with the acrylic pressure-sensitive adhesive.

In the liquid crystal display laminate of the present invention, the acrylic pressure-sensitive adhesive is laminated on one side of the liquid crystal display film, and the acrylic pressure-sensitive adhesive layer surface is further coated with a heating roller or the like to prepare the liquid crystal display glass cell. It is obtained by laminating on the glass B side.

[0033]

The glass cell used in the present invention has a three-layer structure in which glass having a high alkali metal content and glass having a low alkali metal content are bonded together by an adhesive. Thereby, since the glass surface having a large content of the alkali metal expresses higher adhesive strength, after sticking the polarizing plate or the retardation plate through the acrylic pressure-sensitive adhesive layer, even under high temperature and high humidity conditions. It has no problems such as foaming and peeling. Further, in the glass containing a small amount of the alkali metal, the elution of the alkali metal from the surface is small, so that the glass penetrates into the liquid crystal wiring made of indium oxide, tin oxide or the like, and the adverse effect of lowering its resistance value is small. .

[0034]

EXAMPLES Examples of the present invention will be described below. still,
Hereinafter, "part" means "part by weight". (Preparation of glass cell) Table 1 shows the results of elemental analysis of the surfaces of the glass plates A to C used for preparing the glass cell using "ESCA750" (manufactured by Shimadzu Corporation). However,
The unit is mol%. An epoxy-based adhesive obtained by mixing the glass plates A to C with an epoxy resin (manufactured by Yukacel Epoxy Co., Ltd., trade name “Epicoat # 828”) and triethylenetetramine at a ratio of 10: 1 according to the configuration shown in Table 2 was used. 1
0 μm was applied and adhered to obtain glass cells I to VI. (Preparation of Acrylic Adhesive) In a 5-neck separable flask equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen gas inlet tube, and a dropping funnel, 48.8 parts of 2-ethylhexyl acrylate and n-butyl acrylate. 46 parts, acrylic acid 5 parts, hydroxyethyl methacrylate 0.2
Parts, 0.03 parts of n-dodecyl mercaptan and 100 parts of ethyl acetate were added and mixed uniformly by stirring, and then dissolved oxygen was removed by purging with nitrogen gas for 30 minutes while heating. .

Next, while maintaining the temperature at 70 ° C., 0.0
An initiator solution prepared by dissolving 3 parts of benzoyl peroxide in 3 parts of ethyl acetate was dropped by a dropping funnel and then reacted under a nitrogen atmosphere for 15 hours to give a weight average molecular weight of 900,000 and a weight average molecular weight (M
w) to number average molecular weight (Mn) ratio (Mw / Mn) is 3.
Acrylic polymer No. 1 was obtained, and after further reaction, it was diluted with ethyl acetate to obtain a solution of an acrylic copolymer having a solid content of 40% by weight.

Next, based on 100 parts of the solid content of the acrylic copolymer, N, N'-hexamethylene-1,6-
0.03 parts of bis (1-aziridinecarboxamide) (manufactured by Nippon Shokubai Co., Ltd., trade name “HDU”) and trimethylolpropane modified TDI (manufactured by Nippon Polyurethane Company, trade name “Coronate L”, solid content 45% by weight) 0 An acrylic pressure-sensitive adhesive was obtained by adding 40 parts.

(Preparation of Polarizing Plate Adhesive Sheet) The above acrylic adhesive was applied to a release-treated 38 μm polyethylene terephthalate film (hereinafter referred to as “release PET film”), and then in an oven at 110 ° C. for 5 minutes. By drying, an acrylic pressure-sensitive adhesive film having a thickness of 25 μm was obtained.
A 0 μm stretched polyvinyl alcohol-based polarizing plate was laminated with a laminator to obtain a polarizing plate pressure-sensitive adhesive sheet.

(Production of Polarizing Plate / Phase Difference Plate Adhesive Sheet) The release PET film of the polarizing plate adhesive sheet was peeled off, and a stretched polycarbonate type phase difference plate having a thickness of 80 μm was attached, and further the phase difference plate. A 25 μm thick acrylic pressure-sensitive adhesive film was laminated on the surface using a laminator to obtain a polarizing plate / retarder laminate pressure-sensitive adhesive sheet.

(Examples 1 to 3 and Comparative Examples 1 to 8) The above polarizing plate pressure-sensitive adhesive sheet or the polarizing plate / retarder laminate pressure-sensitive adhesive sheet was allowed to stand for 1 week, then cut into a size of 75 mm × 150 mm and separated. The type PET film was peeled off, and the glass cell having the constitution shown in Table 2 was laminated with a laminator so that air bubbles did not enter the acrylic pressure-sensitive adhesive surface to obtain a liquid crystal display laminate. In this case, the laminate of the polarizing plate pressure-sensitive adhesive sheet and the glass cell is referred to as "P / G", and the laminate of the polarizing plate / retarder laminate pressure-sensitive adhesive sheet and the glass cell is referred to as "P / G" below. / R / G ".

The evaluation items and evaluation methods are shown below. (Heat Resistance Adhesion Test) Each of the above liquid crystal display laminates was placed on a glass stand and allowed to stand in a thermostatic chamber at a temperature of 80 ° C. for 100 hours, and the results of microscopic observation of peeling or foaming were shown in Tables 3 to 4. Show.

(Moisture Resistance Adhesion Test) Each of the above liquid crystal display laminates was placed on a glass stand, and the temperature was 60 ° C. and the relative humidity was 90.
The results of microscopic observation of the state of peeling or foaming after standing in a constant temperature and humidity chamber of 100% for 100 hours are shown in Tables 3 and 4.

(Measurement of Alkali Metal Elution Amount from Glass Surface) The results of measuring the alkali metal elution amount from the glass surface according to JIS R3502 are shown in Tables 3 and 4. The unit is mg / cm ² , and 0.3 mg / cm ² or less was regarded as good.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

The structure of the laminated body for liquid crystal display of the present invention is as described above, and since the glass cell for liquid crystal display is formed by bonding two sheets of glass having different alkali metal contents, a polarizing plate is provided on a specific surface thereof. If the retardation plate or its laminate is attached via an acrylic pressure-sensitive adhesive, sufficient adhesive force can be obtained even under high temperature and high humidity conditions, and the liquid crystal wiring in the glass cell is not deteriorated. Therefore, it is suitably used as a liquid crystal display laminate.

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Claims (1)

[Claims] 1. The (A) glass has an alkali metal content of 5
On the glass (B) side of the liquid crystal display glass cell having a three-layer structure in which a glass of less than mol% and a glass of (B) having an alkali metal content of at least 5 mol% or more are laminated via an adhesive layer, A laminate for a liquid crystal display in which an acrylic adhesive and a film for a liquid crystal display are sequentially laminated, wherein the liquid crystal display film is a polarizing plate film, a retardation film, or a lamination of a polarizing plate film and a retardation film. A laminate for a liquid crystal display, which is a sheet.