JPH0545518A - Polarizing plate having tacky adhesive layer - Google Patents

Abstract

(57) [Summary] [Objective] A polarizing plate having good durability is obtained by using a specific pressure-sensitive adhesive in a cellulose-based protective film layer coated to protect a polarizing film. [Structure] A cellulose-based protective film is provided on both sides of a polarizing film, and an acrylic resin pressure-sensitive adhesive layer containing an alkyl ester of orthophosphoric acid is formed on at least one of the protective films.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a polarizing plate having a pressure-sensitive adhesive layer provided on a protective layer such as a cellulose type coating a polarizing film.

[0002]

2. Description of the Related Art Conventionally, a polarizing plate in which both sides of a polarizing film such as a polyvinyl alcohol film having a polarizing property is covered with a protective layer of a cellulosic film such as a cellulose triacetate film is applied to a liquid crystal cell surface. The liquid crystal display plate is used as a liquid crystal display plate, and the application to the liquid crystal cell surface is usually performed by bringing the pressure-sensitive adhesive layer provided on the surface of the polarizing plate into contact with and pressing the cell surface.

[0003]

As the above-mentioned pressure-sensitive adhesive,
Acrylic resins are often used because of their excellent adhesiveness and transparency, but when used in a relatively high humidity environment for a long time, the cellulose film that constitutes the polarizing plate is This causes problems such as decomposition and deterioration, and appearance defects such as foaming and peeling of the pressure-sensitive adhesive when used in a high-humidity and high-temperature environment.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the present situation of polarizing plates as described above, and an object thereof is to provide a polarizing plate excellent in heat resistance and humidity resistance that can be used in an environment of high temperature and high humidity. As a result of research, it was found that the purpose can be achieved when an acrylic resin containing an alkyl ester of orthophosphoric acid is used as an adhesive provided on a polarizing plate.

That is, the present invention is characterized in that "an orthophosphoric acid alkyl ester-containing acrylic resin pressure-sensitive adhesive layer is provided on at least one of the protective layers of a polarizing plate in which both surfaces of a polarizing film are covered with protective layers. A polarizing plate having a pressure-sensitive adhesive layer.

Examples of the constituent components of the acrylic resin of the present invention include a soft monomer component having a low glass transition temperature, a hard comonomer component having a high glass transition temperature, and a small amount of a functional group-containing monomer component, if necessary.

The main monomer components include ethyl acrylate, n-butyl acrylate, iso-acrylate
Butyl, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, cyclohexyl acrylate, etc. Alkyl acrylates having 2 to 12 carbon atoms, n-butyl methacrylate, iso-butyl methacrylate, methacrylic acid 2-ethylhexyl,
Carbon number of alkyl group such as lauryl methacrylate, benzyl methacrylate and cyclohexyl methacrylate is 4 to 12
Examples include methacrylic acid alkyl esters.
Examples of the comonomer component include methyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid alkyl ester having 1 to 3 carbon atoms of an alkyl group such as propyl methacrylate, vinyl acetate, acrylonitrile, methacrylonitrile, and styrene. Can be mentioned.

In addition to the above, the functional group-containing monomer component is a monocarboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, a polyvalent carboxylic acid such as maleic acid, fumaric acid, citraconic acid, glutaconic acid or itaconic acid, and Carboxyl group-containing monomers such as anhydrides, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxylpropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, etc. In addition to hydroxyl group-containing monomers such as N-methylol acrylamide, (meth) acrylamide, dimethylaminoethyl methacrylate, glycidyl methacrylate, allyl glycidyl ether and the like can be mentioned.

Among such functional group-containing monomer components,
It is particularly preferable to use a carboxyl group-containing monomer. The content of the main monomer component cannot be unconditionally specified depending on the types and contents of the comonomer component and the functional group-containing monomer component to be included in other components, but generally, the content of the main monomer is 5
It is preferable to contain 0% by weight or more.

The acrylic resin of the present invention comprises a main monomer,
It is easily produced by a method well known to those skilled in the art, such as radical copolymerization of a comonomer and, if necessary, a functional group-containing monomer in an organic solvent.

The organic solvent used for the above polymerization is
Aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and iso-propyl alcohol, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone Can be mentioned. Specific examples of the polymerization catalyst used for the radical polymerization include azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide and the like, which are ordinary radical polymerization catalysts.

The alkyl group of the alkyl ester of orthophosphoric acid is practically one having about 1 to 20 carbon atoms,
Methyl orthophosphate, ethyl orthophosphate, and propyl orthophosphate are useful (the ester may be mono, di, or tri). The addition amount of the alkyl orthophosphate of the present invention is 100 parts by weight of the acrylic resin. 0.01 to 5.0 parts by weight, preferably 0.3 to 2.0
Parts by weight. If the amount of addition is less than 0.01 parts by weight, the desired effect cannot be obtained, and if it exceeds 5.0 parts by weight, the adhesive properties at high temperatures deteriorate.

Such an acrylic resin pressure sensitive adhesive alone,
Of course, the curing agent can be used, but in order to exert the effects of the present invention more remarkably, a curing agent of about 0.001 to 10% by weight, preferably about 0.01 to 5% by weight is used together. Representative examples of the curing agent include isocyanate compounds, epoxy compounds, aldehyde compounds, amine compounds, metal salts, metal alkoxides, metal chelate compounds, ammonium salts and hydrazine compounds.

Among the curing agents, the isocyanate compounds include tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylol propane tolylene diisocyanate adduct, trimethylol propane xylylene diisocyanate adduct, triphenyl methane triisocyanate and methylene bis (4). -Phenylmethane) triisocyanate, isophorone diisocyanate, and the like, and ketoxime block products or phenol block products thereof.

Examples of the epoxy compound include bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane. Triglycidyl ether, diglycidyl aniline, diglycidyl amine, N, N, N ′, N′-tetraglycidyl m-xylene diamine, 1,3-bis (N, N′-diglycidyl aminomethyl) cyclohexane and the like can be mentioned. ..

Examples of aldehyde compounds include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like. Examples of the amine compound include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin and melamine resin.

As the metal salt, aluminum, iron, copper,
Salts of polyvalent metals such as zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium, salts such as bromide, nitrates, sulfates, acetates, for example, cupric chloride, aluminum chloride, chloride Examples thereof include ferric iron, stannic chloride, zinc chloride, nickel chloride, magnesium chloride, aluminum sulfate, copper acetate and chromium acetate. Examples of the metal alkoxide include tetraethyl titanate, tetraethyl zirconate, and aluminum isopropionate.

Examples of the metal chelate compound include acetylacetone and acetoacetic acid ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. .. Examples of ammonium salts include ammonium chloride, ammonium sulfate, ammonium acetate, ammonium propionate and the like.
Examples of the hydrazine compound include hydrazine, hydrazine hydrate, and their inorganic salts such as base salts, sulfates and phosphates, and organic acid salts such as formic acid and oxalic acid.

The polarizing plate of the present invention is obtained mainly by using a polyvinyl alcohol type polarizing plate film as a base material, providing a protective layer thereon, and then adding an adhesive layer and a peeling film. The adhesive layer and the peeling film can be added by forming a pressure-sensitive adhesive layer on the peeling film and sticking a polarizing film on the peeling film, or conversely, forming a pressure-sensitive adhesive layer on the polarizing film and peeling the peeling film on it. The method of pasting the film is usually adopted.

The polarizing plate having the pressure-sensitive adhesive layer thus obtained is appropriately cut at the time of use, and the release film is peeled off.
Laminated with mating substrate glass or other substrate,
Used for antiglare or as sunglasses. Further, by providing a reflecting plate and / or a semitransparent layer in the polarizing plate having the pressure-sensitive adhesive layer, the polarizing plate is used as a reflective or semitransparent liquid crystal display plate. A foil or plate of aluminum or the like is usually used as the reflector. Further, the translucent layer has a reflectance and a transmittance selected so that it can be used for both a reflection type and a transmission type, and a material is appropriately selected.

For liquid crystals, an ultraviolet absorbing sheet may be attached to protect the liquid crystals. Polyester-isocyanate-based adhesives are suitable for adhering these various materials to the polarizing film. The polyvinyl alcohol polarizing film has an average degree of polymerization of 300 to 5,000 and a degree of saponification of 85 to 100 mol%.
The one that is stretched about 2 to 8 times in the uniaxial direction is used.

Examples of the protective film include conventionally known cellulose acetate film, acrylic film, polyester resin film, polyolefin resin film, polycarbonate film, polyether ether ketone film, and polysulfone film.

[0023]

[Working] The polarizing plate of the present invention has improved durability under high temperature and high humidity conditions, and its polarization degree does not decrease even when left for a long time. Further, there is no foaming or peeling of the pressure-sensitive adhesive layer. Utilizing such properties, it is used for liquid crystal displays, and is particularly useful for vehicles, various industrial instruments, and displays of household electric appliances.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples. The degree of polarization referred to in the present invention is expressed by the equation 1.

[0025]

[Equation 1] Here, H ₁₁ is the transmittance (%) measured with a spectrophotometer in a state where the two polarizing film samples are superposed so that the orientation directions of the polarizing films are the same, and H _{1 is} Is the transmittance (%) measured in a state where the two samples were superposed so that the orientation directions of the polarizing films were orthogonal to each other. Example 1 Acrylic resin (A) (resin component: 2-ethylhexyl acrylate / n-butyl acrylate / acrylic acid /
Hydroxyethyl methacrylate / vinyl acetate = 45% by weight / 46% by weight / 3.9% by weight / 0.1% by weight / 5% by weight) 100 parts by weight and 15 parts by weight of pentaerythritol ester of polymerized rosin with orthophosphoric acid dimethyl ester To a 45 wt% solution added with 0.5 part by weight, tolylene diisocyanate (3 mol) of trimethylolpropane (1
2.0 parts by weight of a 75% by weight ethyl acetate solution of the (mole) adduct was added to obtain an adhesive. The adhesive was dried on a glass plate having a thickness of 1.1 mm using an applicator to give a dry coating amount of 25.
It was applied at a ratio of g / m ² and dried at 100 ° C. for 1 minute to obtain an adhesive plate.

On the other hand, a polyvinyl alcohol polarizing film having a film thickness of 25 μm (average degree of polymerization 1700, average degree of saponification 9
9.5 mol%, stretched 5 times) to prepare a polarizing plate in which both sides are laminated with a 80 μm thick triacetyl cellulose film,
The pressure-sensitive adhesive plate was laminated on one surface of the plate and pressed by a roller to manufacture a polarizing plate. Heat resistance test (8
0 ℃, left for 1000 hours), humidity resistance test (60 ℃, 90
% RH, left for 1000 hours). The results are shown in Table 2.

Examples 2 to 4 and Comparative Example 1 Table 1 instead of the acrylic resin (A) in Example 1
The acrylic resins (B) to (D) shown in Table 2 are used, and Table 2
An adhesive having the adhesive composition shown by was produced. Table 2 also shows the physical property values measured in the same manner as in the same example.

[0028]

[Table 1]

[Table 2]

[0029]

INDUSTRIAL APPLICABILITY In the present invention, at least one of the protective layers of a polarizing plate having both sides of a polarizing film coated with protective layers,
By providing the acrylic resin adhesive layer containing an alkyl ester of orthophosphoric acid, a polarizing plate having excellent durability can be obtained.

Claims (3)

[Claims] 1. A pressure-sensitive adhesive layer comprising an acrylic resin pressure-sensitive adhesive layer containing an alkyl ester of orthophosphoric acid, which is provided on at least one of the protective layers of a polarizing plate in which both sides of a polarizing film are covered with protective layers. A polarizing plate having. 2. The polarizing plate according to claim 1, wherein the acrylic pressure sensitive adhesive is mixed with a curing agent. 3. The polarizing plate according to claim 1, wherein the polarizing film is a polyvinyl alcohol film.