JP3022993B2 - Polarizing plate having an adhesive layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a polarizing plate in which a pressure-sensitive adhesive layer is provided on a protective layer made of cellulose or the like which covers a polarizing film.

[0002]

2. Description of the Related Art Conventionally, a polarizing plate in which both surfaces of a polarizing film such as a polyvinyl alcohol film having a polarizing property are coated with a protective layer of a cellulose film such as a cellulose triacetate film is applied to a liquid crystal cell surface. In general, application to the liquid crystal cell surface is performed by bringing an adhesive layer provided on the polarizing plate surface into contact with the cell surface and pressing it.

[0003]

The above-mentioned pressure-sensitive adhesives include:
Acrylic resins are often used for their excellent adhesiveness and transparency.However, in long-term use in relatively high humidity environments, the cellulose film that constitutes the polarizing plate is There are problems such as decomposition and deterioration, and appearance defects such as foaming and peeling of the pressure-sensitive adhesive layer 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 above-mentioned current situation of polarizers, and has as its object to provide a polarizer excellent in heat resistance and moisture resistance that can withstand use in a high-temperature and high-humidity environment. As a result of research, it has been found that the purpose can be achieved when an acrylic resin containing a silane compound having an epoxy group is used as an adhesive provided on a polarizing plate.

[0005] That is, the present invention provides a polarizing film comprising a polarizing film in which both surfaces of a polarizing film are coated with a protective layer, at least one of which is provided with a silane compound-containing acrylic resin pressure-sensitive adhesive layer having an epoxy group. Polarizing plate having a pressure-sensitive adhesive layer ”.

The acrylic resin composition of the present invention includes 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 as required.

The main monomer components include ethyl acrylate, n-butyl acrylate and iso-acrylate.
Butyl, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, cyclohexyl acrylate, etc., alkyl esters of alkyl groups having about 2 to 12 carbon atoms, n-butyl methacrylate, iso-butyl methacrylate, methacrylic acid 2-ethylhexyl,
Alkyl groups such as lauryl methacrylate, benzyl methacrylate and cyclohexyl methacrylate have 4 to 12 carbon atoms
About methacrylic acid alkyl ester,
Examples of the comonomer component include methyl methacrylate, methyl methacrylate, ethyl methacrylate, alkyl methacrylate having 1 to 3 carbon atoms such as propyl methacrylate, vinyl acetate, acrylonitrile, methacrylonitrile, and styrene. No.

In addition to the above, the functional group-containing monomer components include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, polycarboxylic acids such as maleic acid, fumaric acid, citraconic acid, glutaconic acid and 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, and the like 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,
Particularly, use of a carboxyl group-containing monomer is preferred. Although the content of such a main monomer component cannot be unconditionally defined by the type or content of a comonomer component or a functional group-containing monomer component to be contained in another component, 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 can be 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 in the polymerization includes:
Aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. And the like. Specific examples of the polymerization catalyst used in the radical polymerization include azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide and the like, which are ordinary radical polymerization catalysts.

The silane compound having an epoxy group of the present invention is not particularly limited, but includes methyltri (glycidyl) silane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane,
-Glycidoxytriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like, and preferably, 3-glycidoxypropyltrimethoxysilane is used. The addition amount of the silane compound of the present invention is 0.01 to 100 parts by weight of the acrylic resin.
It is 10 parts by weight, preferably 0.05 to 3.0 parts by weight. If the amount is less than 0.01 part by weight, the desired effect cannot be obtained, and if it exceeds 10 parts by weight, the adhesive properties at high temperatures are reduced.

[0013] Such an acrylic resin pressure-sensitive adhesive alone,
Of course, it can be used, but in order to make the effect of the present invention more remarkable, a curing agent of 0.001 to 10% by weight, preferably about 0.01 to 5% by weight is used in combination. 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, tolylene diisocyanate adduct of trimethylolpropane, xylylene diisocyanate adduct of trimethylolpropane, triphenylmethane triisocyanate, methylene bis (4 -Phenylmethane) triisocyanate, isophorone diisocyanate, and the like, and ketoxime-blocked products or phenol-blocked products thereof.

As the epoxy compound, 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, diglycidylaniline, diglycidylamine, N, N, N ′, N′-tetraglycidyl m-xylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane and the like. ,

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

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

Examples of the metal chelate compound include acetylacetone and acetoacetate coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. . Examples of the ammonium salt include ammonium chloride, ammonium sulfate, ammonium acetate, ammonium propionate and the like.
Examples of the hydrazine compound include hydrazine, hydrazine hydrate, and inorganic salts such as base salts, sulfates, and phosphates thereof, 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-based polarizing plate film as a base material, providing a protective layer thereon, and then adding a pressure-sensitive adhesive layer and a release film. As a method of adding an adhesive layer and a release film, a method in which an adhesive layer is provided on a release film and a polarizing film is attached thereon, or conversely, an adhesive layer is provided on a polarizing film and peeled therefrom A method of attaching a film is usually employed.

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 glass or other substrates that are mating substrates,
Used for anti-glare or as sunglasses. Further, by providing a reflection plate and / or a translucent layer in a polarizing plate having the above-mentioned pressure-sensitive adhesive layer, it can be used for a reflection type or semi-transmission type liquid crystal display panel. A foil or plate of aluminum or the like is usually used as the reflection plate. Further, as the translucent layer, the reflectance and the transmittance are selected so that the translucent layer can be used for both the reflection type and the transmission type, and the material is appropriately selected.

For liquid crystal, an ultraviolet absorbing sheet may be attached to protect the liquid crystal. In order to adhere these various materials to the polarizing film, a polyester-isocyanate-based adhesive is suitable. As a polyvinyl alcohol-based polarizing film, the average degree of polymerization is 300 to 5000, and the degree of saponification is 85 to 100 mol%.
Which are stretched about 2 to 8 times in a uniaxial direction.

Examples of the protective film include conventionally known cellulose acetate-based films, acrylic films, polyester-based resin films, polyolefin-based resin films, polycarbonate-based films, polyetheretherketone-based films, and polysulfone-based films.

[0023]

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

[0024]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Incidentally, the degree of polarization referred to in the present invention is shown by Expression 1.

[0025]

(Equation 1) Here H ₁₁ at the time of superposition of two polarizing film sample, transmittance was measured using a spectrophotometer in a state in which the orientation direction is superposed so as to become the same direction of the polarizing film (%), H ₁ Is the transmittance (%) measured in a state where the polarizing films are superposed such that the orientation directions of the polarizing films are orthogonal to each other when the two samples are superposed. Example 1 Acrylic resin (A) (resin component: 2-ethylhexyl acrylate / n-butyl acrylate / acrylic acid /
3-glycidoxy in 100 parts by weight of hydroxyethyl methacrylate / vinyl acetate = 45% by weight / 46% by weight / 3.9% by weight / 0.1% by weight / 5% by weight) and 15 parts by weight of pentaerythritol ester of polymerized rosin 2.0 parts by weight of a 75% by weight ethyl acetate solution of a tolylene diisocyanate (3 mol) adduct of trimethylolpropane (1 mol) was added to a 45% by weight solution containing 1.0 part by weight of propyltrimethoxysilane. An adhesive was obtained. The adhesive was applied on a 1.1 mm-thick glass plate using an applicator at a dry coating weight of 25 g / m ² ,
For 1 minute to obtain an adhesive plate.

On the other hand, a 25 μm-thick polyvinyl alcohol polarizing film (average degree of polymerization 1700, average degree of saponification 9
(9.5 mol%, stretched 5 times) to form a polarizing plate laminated on both sides with a triacetyl cellulose film having a thickness of 80 μm.
The pressure-sensitive adhesive plate was laminated on one surface thereof, and pressed with a roller to produce a polarizing plate. Heat resistance test (8
0 ° C, 1000 hours), moisture resistance test (60 ° C, 90 hours)
% RH for 1000 hours). Table 2 shows the results.

Examples 2 to 4, Comparative Example 1 In Example 1, Table 1 was used instead of the acrylic resin (A).
Table 2 using the acrylic resins (B) to (D) shown in Table 2.
The adhesive of the adhesive composition shown by was manufactured. Table 2 also shows the physical properties measured in the same manner as in the same example.

[0028]

[Table 1]

[Table 2]

[0029]

According to the present invention, at least one of the protective layers of the polarizing plate in which both surfaces of the polarizing film are covered with the protective layers,
By providing a silane compound-containing acrylic resin pressure-sensitive adhesive layer having an epoxy group, a polarizing plate having excellent durability can be obtained.

Claims (3)

(57) [Claims] 1. A pressure-sensitive adhesive layer comprising an acrylic resin-containing pressure-sensitive adhesive layer having an epoxy group provided on at least one of the protective layers of a polarizing plate having both surfaces of a polarizing film covered with protective layers. Polarizing plate with 2. The polarizing plate according to claim 1, wherein a curing agent is compounded in the acrylic pressure-sensitive adhesive. 3. The polarizing plate according to claim 1, wherein the polarizing film is a polyvinyl alcohol film.