JPH07331205A - Pressure-sensitive adhesive composition for liquid crystal element and liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain a pressure-sensitive adhesive composition for a liquid crystal element presenting good adhesiveness without causing the debonding or blister of a polarizing plate, etc., and capable of releasing and applying again the polarizing plate, etc., without damaging the liquid crystal element. CONSTITUTION:This adhesive (composition) comprises (a) 100 pts.wt. of a copolymer from 50-99.9wt.% of a (meth)acrylic 4-12C alkyl-ester, 0.1-10wt.% of an ethylenic unsaturated monomer having polar group in the molecule and 0-49.9wt.% of a monomer copolymerizable therewith and (b) 0.5-20 pts.wt. of a higher fatty acid and/or derivative therefrom with the phase transition temperature from solid to liquid phase within 30-60 deg.C. The other objective liquid crystal element is obtained by applying a polarizing plate, etc.,on a substrate through this adhesive composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal element or a liquid crystal display device (hereinafter sometimes simply referred to as “LCD”).
TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition for use, and a liquid crystal device manufactured using the pressure-sensitive adhesive composition. More specifically, the present invention is a pressure-sensitive adhesive composition for a liquid crystal device, which can be peeled off at the time of manufacturing an LCD and has excellent durability under high temperature and high humidity conditions, and a pressure-sensitive adhesive composition manufactured using this pressure-sensitive adhesive composition. Liquid crystal device.

[0002]

BACKGROUND OF THE INVENTION A liquid crystal element is composed of two substrates having transparent electrodes arranged on the surface in contact with liquid crystal, a liquid crystal material filled between the two substrates, and outer surfaces of the two substrates. Or a laminated plate of a polarizing plate and a retardation plate.

In such a liquid crystal element, a polarizing plate or a laminated plate of a polarizing plate and a retardation plate is attached to the surface of a substrate by using a pressure sensitive adhesive. An acrylic resin is often used as a pressure-sensitive adhesive used for attaching such a polarizing plate or a laminated plate of a polarizing plate and a retardation plate to the surface of a substrate.

In recent years, the liquid crystal element has a remarkably wide range of use such as a display unit of a desk-top electronic computer, a display panel of a personal computer, an in-vehicle liquid crystal display device, a screen of a television, and the like, and thus the application is widened. Accordingly, the usage environment of liquid crystal elements has become extremely severe.
Accordingly, it is desirable that the adhesive strength between the polarizing plate or the laminated plate of the polarizing plate and the retardation plate and the glass is high so as to withstand such use conditions, and that the high adhesive strength does not fluctuate for a long period of time. From this point of view, an acrylic resin adhesive is used.

By the way, in the process of manufacturing a liquid crystal element using such an adhesive, when a problem occurs in bonding the polarizing plate or the laminated plate of the polarizing plate and the retardation plate,
It is necessary to peel off the polarizing plate or the laminated plate of the polarizing plate and the retardation plate, and reattach the polarizing plate or the laminated plate of the polarizing plate and the retardation plate to manufacture a liquid crystal element. That is,
Compared with a polarizing plate or a laminated plate of a polarizing plate and a retardation plate, the liquid crystal cell and the liquid crystal material filled in the cell are extremely expensive, and thus the polarizing plate or the polarizing plate and the retardation plate are Since the liquid crystal material and the cell itself filled with the liquid crystal material often have no problem even if the laminated plate is poorly adhered, reattach the polarizing plate or the laminated plate of the polarizing plate and the retardation plate. If so, good liquid crystal performance is exhibited.

However, since the environment in which the liquid crystal element is used has become considerably severe as described above, the adhesive strength of the adhesive for adhering the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is also extremely high. A polarizing plate or a laminated plate of a polarizing plate and a retardation plate, which has been pasted with an acrylic resin-based adhesive, has a glass substrate at the time of peeling because of high adhesive strength. In many cases, it cannot be used as a liquid crystal element because it is damaged or the width of the gap filled with the liquid crystal material changes. Further, even if the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is peeled off, the adhesive remains on the glass substrate, and in fact, a new polarizing plate or the laminated plate of the polarizing plate and the retardation plate is attached. There is a problem that you cannot wear it.

Further, as the use range and purpose of such liquid crystal element materials have become widespread in recent years, they are often exposed to more severe environmental conditions, such as liquid crystal elements for vehicles, and thus are used as pressure sensitive adhesives for liquid crystals. Is required to have the property (durability) that foaming or peeling does not occur in the polarizing plate or the laminated plate of the polarizing plate and the retardation plate even under such severer conditions of high temperature and high humidity. The adhesive strength required for the pressure-sensitive adhesive is higher.

Under such circumstances, the pressure-sensitive adhesive used for sticking the polarizing plate or the laminated plate of the polarizing plate and the retardation plate to the glass substrate of the liquid crystal element has a stable adhesive strength for a long time. It is more preferable that the polarizing plate or the laminated plate of the polarizing plate and the retardation plate can be easily peeled off without damaging the liquid crystal element when the peeling is attempted.

[0009]

It is an object of the present invention to exhibit high adhesive strength under higher temperature and high humidity conditions, and to remove a polarizing plate or a laminated plate of a polarizing plate and a retardation plate from a liquid crystal glass substrate. Without damaging the liquid crystal element,
An object of the present invention is to provide a pressure-sensitive adhesive composition for a liquid crystal element, which has the contradictory characteristics that are required for a pressure-sensitive adhesive for a liquid crystal element and that can be easily peeled off.

Another object of the present invention is to provide a liquid crystal device in which a polarizing plate or a laminated plate of a polarizing plate and a retardation plate is adhered on a glass substrate with the above adhesive composition. .

[0011]

SUMMARY OF THE INVENTION The pressure-sensitive adhesive composition for a liquid crystal device of the present invention comprises (a) 50 to 99.9% by weight of a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms and a molecule. A copolymer of 0.1 to 10% by weight of an ethylenically unsaturated monomer having a polar group therein and 0 to 49.9% by weight of a monomer copolymerizable therewith, and (b) from solid phase to liquid phase Has a phase transition temperature in the range of 25 to 85 ° C., and at least a part of the organic compound is soluble in the copolymer (a) at the phase transition temperature or higher, and the organic compound (b) is It is characterized in that it is contained in an amount of 0.5 to 20 parts by weight with respect to 100 parts by weight of the copolymer (a).

Further, the liquid crystal element of the present invention is
In a liquid crystal device in which a liquid crystal is filled in a gap formed by two substrates on which a polarizing plate or a laminated plate of a polarizing plate and a retardation plate is arranged, the polarizing plate or the polarizing plate The laminated plate with the retardation plate is (a) having 4 to 12 carbon atoms.
50% to 99.9% by weight of (meth) acrylic acid alkyl ester having an alkyl group, 0.1 to 10% by weight of an ethylenically unsaturated monomer having a polar group in the molecule, and a monomer copolymerizable therewith ˜49.9% by weight, and (b) solid phase to liquid phase transition temperature of 25
To 85 ° C., consisting of an organic compound at least a part of which dissolves in the copolymer (a) at the phase transition temperature or higher, and the organic compound (b) is the copolymer (a). 1
The pressure-sensitive adhesive composition for liquid crystal elements is contained in an amount of 0.5 to 20 parts by weight with respect to 00 parts by weight, and is adhered.

In the present invention, the organic compound (b)
Preferably has a molecular weight of 200 to 5,000, and the organic compound (b) is a carboxylic acid compound and / or a derivative thereof, and the derivative of the carboxylic acid compound has 4 carbon atoms. Ester compounds derived from -24 alcohols and carboxylic acid compounds,
Selected from the group consisting of an ester compound of a C4-24 fatty acid and an alcohol, a reaction product of a C4-24 fatty acid and an amino compound, and a polymer of the carboxylic acid compound and / or its derivative. Preferably, the compound is

After sticking the polarizing plate or the laminated plate of the polarizing plate and the retardation plate and the liquid crystal element substrate such as glass, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is detached from the substrate. In order to prevent this, the composition of the adhesive must be determined so that the adhesive strength increases as the temperature and humidity increase. However, in the manufacturing process of the liquid crystal element, when a problem occurs in the bonding of the polarizing plate or the laminated plate of the polarizing plate and the retardation plate, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is peeled from the substrate. Then it is necessary to re-attach the polarizing plate or the laminated plate of the polarizing plate and the retardation plate,
In this case, when the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is peeled off, it must be peeled off so as not to damage the glass substrate or the like.

Particularly, in a manufacturing process of a liquid crystal element, it may be exposed to a high temperature (for example, 80 ° C.) for a long time (for example, 10 hours), and a polarizing plate or a polarizing plate and a retardation plate attached to the substrate surface by such heating. The laminated plate of and is strongly adhered to the surface of the substrate. Since this adhesive strength is irreversible, the adhesive strength does not decrease even when the temperature becomes low.

Therefore, in the conventional adhesive, even if a problem occurs in the adhesion state of the polarizing plate or the laminated plate of the polarizing plate and the retardation plate after the heating step, the polarizing plate or the polarizing plate and the retardation plate are laminated. It was difficult to peel the plate.

The inventor of the present invention blends a specific compound, which undergoes a phase transition depending on environmental conditions and changes the degree of compatibilization with an acrylic polymer, into a specific acrylic adhesive to obtain the optimum optimum under various temperature conditions. The present invention has been completed based on the finding that various adhesive strengths can be obtained, and that these adhesive strengths can be reversibly changed with temperature.

That is, the pressure-sensitive adhesive composition for a liquid crystal device of the present invention undergoes a phase transition (state change) from a solid to a liquid in the range of 25 to 85 ° C. to a specific acrylic copolymer, and at least a part thereof. By blending a specific compound capable of dissolving the above compound, this compound is compatible with the acrylic copolymer in a high temperature range (a temperature higher than the phase transition temperature, the same applies hereinafter), and high adhesive strength is exhibited. On the other hand, in the low temperature range (temperature lower than the phase transition temperature,
(The same applies hereinafter), crystals of this compound precipitate and the adhesive strength is reduced. When adhesion failure occurs in the polarizing plate or the laminated plate of the polarizing plate and the retardation plate, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate may be peeled off in a working environment of 20 to 25 ° C. In many cases, therefore, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate can be peeled off without damaging the liquid crystal element, and the adhesive hardly remains on the substrate.

Although the pressure-sensitive adhesive of the present invention has the characteristic that it can be peeled off in the manufacturing process of a liquid crystal element as described above, it can be used under severe conditions such as high temperature and high humidity. Even when a liquid crystal element is used, the pressure-sensitive adhesive composition of the present invention exhibits good adhesiveness, and even when used under such conditions, a polarizing plate or a laminate of a polarizing plate and a retardation plate is laminated. Adhesion failure such as blistering and peeling is unlikely to occur on the board.

A liquid crystal element to which a polarizing plate or a laminated plate of a polarizing plate and a retardation plate is attached with the adhesive composition of the present invention is a laminated body of a transparent substrate and a polarizing plate or a polarizing plate and a retardation plate. The adhesion to the plate is good, and the adhered state of the two is stable for a long period of time. Therefore, the liquid crystal device of the present invention can maintain excellent optical characteristics for a long period of time.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The pressure-sensitive adhesive composition for a liquid crystal element and the liquid crystal element of the present invention will be specifically described.

The pressure-sensitive adhesive composition for liquid crystal device of the present invention comprises
It is composed of an acrylic copolymer (a) and an organic compound (b) that changes state under specific temperature conditions. The acrylic copolymer is a copolymer of (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms and an ethylenically unsaturated monomer containing a polar group in the molecule, and If necessary, other monomers copolymerizable with these may be copolymerized.

Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms used herein include butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. , Lauryl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, cyclohexyl (meth) acrylate and phenyl (meth) acrylate.

These can be used alone or in combination. In the acrylic copolymer (a) used in the present invention, repeating units derived from the (meth) acrylic acid ester are copolymerized in an amount of 50 to 99.9% by weight, and It is preferred that it is copolymerized in an amount of 80 to 98% by weight.

Further, examples of the ethylenically unsaturated monomer containing a polar group in the molecule include acrylic acid, methacrylic acid, β-carboxyethyl acrylate, 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth). ) Acrylate, chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and glycidyl (meth) acrylate. be able to.

These can be used alone or in combination. In the acrylic copolymer (a) used in the present invention, a repeating unit derived from an ethylenically unsaturated monomer containing a polar group in the molecule is 0.
Copolymerized in an amount of 1 to 10% by weight, and further 2 to 10
It is preferred that they are copolymerized in an amount of wt%.

In addition to the above-mentioned (meth) acrylic acid ester and polar group-containing monomer, other monomers copolymerizable with these monomers include (meth) acrylic acid alkyl ester having an alkyl group having 3 or less carbon atoms. Having an alkyl group having 13 or more carbon atoms (meth)
Mention may be made of acrylic acid alkyl esters, styrene-based monomers, and vinyl-based monomers. As a specific example, as a (meth) acrylic acid alkyl ester having an alkyl group having 3 or less carbon atoms, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate and isopropyl (meth) acrylate can be mentioned, and as the (meth) acrylic acid alkyl ester having an alkyl group having 13 or more carbon atoms, stearyl (meth) acrylate, isostearyl (meth) Mention may be made of acrylates and behenyl (meth) acrylates.

Further, as an example of the styrene-based monomer,
Alkyl styrenes such as styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene; fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene. And halogenated styrenes such as iodostyrene; and also nitrostyrene, acetylstyrene and methoxystyrene.

Examples of vinyl monomers include vinylpyridine, vinylpyrrolidone, vinylcarbazole, divinylbenzene, vinyl acetate and acrylonitrile; conjugated diene monomers such as butadiene, isoprene and chloroprene; halogens such as vinyl chloride and vinyl bromide. Vinyl chloride; vinylidene halide such as vinylidene chloride can be mentioned.

These monomers can be used alone or in combination. The repeating unit derived from the other monomer in the acrylic copolymer (a) used in the present invention is copolymerized in an amount of 0 to 49.9% by weight, and further 0 to 20% by weight. % Copolymerization is preferred.

As described above, the acrylic copolymer (a)
The compatibility between the copolymer (a) and the organic compound (b) can be adjusted by adjusting the copolymerization amount of the monomer in the above.

The acrylic copolymer (a) used in the present invention is prepared, for example, by adding the above monomers to a reaction solvent and replacing the air in the reaction system with an inert gas such as nitrogen gas. After that, if necessary, in the presence of a reaction initiator, the mixture can be heated and stirred to cause a polymerization reaction, whereby the product can be produced.

As the reaction solvent used here, an organic solvent is used, and specifically, aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as n-hexane, ethyl acetate and butyl acetate. And the like, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, and ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.

As the reaction initiator, for example, azobisisobutyronitrile, benzoyl peroxide, diester
-tert-Butyl peroxide and cumene hydroperoxide can be used.

The reaction temperature of the above polymerization reaction is usually 50 to
90 ° C, the reaction time is usually 2 to 20 hours, preferably 4
~ 12 hours. In the reaction as described above, the monomer can be blended according to the amount of each repeating unit in the acrylic copolymer (a) to be obtained.

The reaction solvent is a total amount of monomers of 100.
It is used in an amount of 50 to 1000 parts by weight with respect to parts by weight. Further, the reaction initiator is usually from 0.01 to
Used in an amount of 10 parts by weight.

By carrying out the reaction as described above, the acrylic copolymer (a) used in the present invention is obtained as a solution or a dispersion liquid in which the reaction solvent contains the copolymer in an amount of 10 to 70% by weight. . In the present invention, after removing the solvent from this dispersion liquid or solution, the obtained acrylic copolymer (a) may be mixed with other components. However, in the present invention, the acrylic copolymer (a) is mixed with other components in a state of being dispersed or dissolved in the reaction solvent without removing the reaction solvent obtained as described above. Is preferred. Generally, the acrylic copolymer (a) obtained as described above is stably dispersed or dissolved in a reaction solvent, and by using such a dispersion or solution as it is, each component is It can be mixed uniformly.

The acrylic copolymer (a) used in the present invention has a weight average molecular weight of usually 100,000 to 15,000,000, preferably 300,000 to 800,000.

The pressure-sensitive adhesive composition for liquid crystal devices of the present invention contains an organic compound (b) having a predetermined phase transition temperature. The organic compound (b) has a phase transition temperature from a solid phase to a liquid phase within a range of 25 to 85 ° C., preferably 30.
It is in the range of -60 ° C and consists of an organic compound that is at least partially soluble in the copolymer (a) above the phase transition temperature.

The organic compound (b) is a carboxylic acid compound and / or a derivative thereof, and the organic compound has a carboxyl group bonded to an alkyl group or an aryl group. Specific examples thereof include cyclohexylcarboxylic acid, decanoic acid, lauric acid, myristic acid, 2-butenoic acid, palmitic acid and stearic acid.

As the derivative of the carboxylic acid compound, an ester compound derived from an alcohol and a carboxylic acid compound having 4 to 24 carbon atoms, preferably 6 to 22 carbon atoms, and 4 to 24 carbon atoms, preferably 6 to 22 carbon atoms. Ester compound of 22 fatty acid and alcohol, or 4 carbon atoms
There is a reaction product of -24, preferably 6-22, fatty acid with an amino compound, and examples thereof include polymers of their derivatives. These can be used alone or in combination.

Specific examples of the above ester compounds include tetradecyl palmitate, stearyl (meth) acrylate, behenyl (meth) acrylate, methyl stearate, myristyl myristate, and distearyl phthalate. it can.

Examples of the reaction product of a fatty acid and an amino compound include reaction products of the above fatty acid with an amide, N-methylamide, anilide, β-naphthylamide, phenylhydrazide or N-acylglucosamine, and Examples thereof include cyclohexylamine salts of fatty acids and benzylamine salts of fatty acids.

By adjusting the number of carbon atoms of the alkyl group, esterifying and aminating in this way, the phase transition temperature and the compatibility of the above compound with the acrylic copolymer (a) can be adjusted. .

Further, examples of the derivative of the carboxylic acid compound used in the present invention include reaction products of ester compounds and amino acid compounds of the above carboxylic acid compounds or their derivatives, polymers produced by thermal polymerization, and organic peroxides. Polymers and oligomers reacted in the presence of a catalyst such as nickel and nickel can be mentioned.

Particularly in the present invention, the molecular weight is 200 to 500.
Carboxylic acid compounds and derivatives thereof in the range of 0 are preferable, and carboxylic acid compounds and derivatives thereof in which the molecular weight is in the range of 200 to 3000 are particularly preferable.

By adjusting the molecular weight in this way,
The phase transition temperature and the compatibility of the above compound with the acrylic copolymer (a) can be adjusted. These derivatives can be used alone or in combination.

The carboxylic acid compound and its derivative having the above-mentioned molecular weight are well compatible with the acrylic copolymer at least in part in the high temperature range, and at the low temperature range, the acrylic copolymer is good. Therefore, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate can be peeled off from the substrate surface without satisfactorily depositing on the liquid crystal element substrate surface and damaging the liquid crystal element.

Despite the fact that the adhesive composition of the present invention has good adhesiveness, it can be easily peeled off from the liquid crystal element substrate after the heat treatment because the compounded carboxylic acid compound and It is considered that this is because / or its derivative acts as follows.

Since the adhesive composition of the present invention contains a carboxylic acid compound and / or a derivative thereof which undergoes a phase transition under a specific temperature condition, the carboxylic acid can be used in a low temperature range, that is, at a temperature below the phase transition temperature. The compound and / or its derivative (b) becomes partially incompatible with the acrylic copolymer (a) polymer and is localized on the surface of the acrylic copolymer (a). , At that part, it becomes a state of being separated and crystallized. In the high temperature range, that is, at a temperature above the phase transition temperature, the carboxylic acid compound
Alternatively, its derivative (b) is an acrylic copolymer (a)
On the other hand, at least a part (preferably almost all) becomes a completely compatible state and uniformly diffuses inside the acrylic copolymer (a). Then, when the temperature of the completely compatible state is again lowered to the phase transition temperature or lower, the carboxylic acid compound and / or the derivative (b) thereof is again converted into the acrylic copolymer (a ) Is partially incompatible with each other, is localized on the surface of the acrylic polymer, and is separated and crystallized at that site. Therefore, the adhesive composition of the present invention has a high adhesive strength in a high temperature region, and has an adhesive strength in a low temperature region to such an extent that it does not damage the liquid crystal element during peeling,
Moreover, this adhesive strength reversibly changes with temperature.

The carboxylic acid compound and / or its derivative as described above is contained in the composition of the present invention in an amount of 0.5 to 20 parts by weight, preferably 0 to 20 parts by weight, based on 100 parts by weight of the acrylic copolymer. It is contained in an amount of 0.5 to 10 parts by weight. If the amount of the carboxylic acid compound and / or its derivative deviates from the above range and is small, the effect of adding these compounds will not be exhibited, and if it deviates from the above range and is large,
The initial adhesive strength and the adhesive strength at high temperature are reduced. That is, in the low temperature range, the adhesive strength between the adherend and the acrylic polymer is smaller than that of the acrylic copolymer (a) containing no carboxylic acid compound and / or its derivative (b), but in this case, The adhesive strength must be sufficient to bond the polarizing plate or the laminated plate of the polarizing plate and the retardation plate to the liquid crystal element substrate. The amount of carboxylic acid compound and / or its derivative (b) required for this is
20 parts by weight per 100 parts by weight of the acrylic copolymer (a)
It is necessary to be less than or equal to parts by weight.

In the high temperature range, the carboxylic acid compound and / or its derivative (b) act as an external plasticizer of the acrylic copolymer (a) to act as the acrylic copolymer (a). The physical properties such as elastic modulus of are changed, and the stress relaxation property is improved. Therefore, as compared with the acrylic copolymer (a) containing no carboxylic acid compound and / or its derivative, the adhesive composition of the present invention has an adhesive strength with an adherend equal to or higher than that of the acrylic copolymer (a). become. In order to exert such an action, the carboxylic acid compound and / or its derivative (b) is an acrylic copolymer (a) 1.
It is necessary to add 0.5% by weight or more to 00 parts by weight.

The phase transition temperature of the carboxylic acid compound and / or its derivative can be adjusted by appropriately selecting the number of carbon atoms of the alkyl group and the structure or molecular weight of the compound within the scope of the present invention.

The pressure-sensitive adhesive composition for liquid crystal elements of the present invention may contain a cross-linking agent which is usually used. Examples of the cross-linking agent include conventionally known ones such as an isocyanate cross-linking agent, a melamine cross-linking agent, a metal chelate cross-linking agent, an epoxy cross-linking agent and a peroxide cross-linking agent. Such a cross-linking agent is usually added just before using the adhesive composition of the present invention. The amount of the crosslinking agent used is 100% of the acrylic copolymer (a).
It is generally preferable that the amount is 15 parts by weight or less with respect to parts by weight.
Further, instead of using such a cross-linking agent or after using the cross-linking agent, irradiation with an electron beam or an ultraviolet ray may be performed to form a cross-linked structure (so-called cross-linking treatment).

The pressure-sensitive adhesive composition for liquid crystal elements of the present invention comprises
Further, it may contain other components. Examples of other components that can be added to the pressure-sensitive adhesive composition for liquid crystal devices of the present invention include tackifiers, plasticizers, dyes, and inorganic fillers. As the above-mentioned other components themselves, already known components can be blended alone or in combination.

In the liquid crystal device of the present invention, a polarizing plate or a laminated plate of a polarizing plate and a retardation plate is adhered to a substrate with the above pressure-sensitive adhesive composition for liquid crystal devices. FIG. 1 schematically shows a cross section of the liquid crystal element of the present invention.

As shown in FIG. 1, the liquid crystal element 1 of the present invention.
Has two substrates 2 and 2 and a liquid crystal 3 filled in a gap formed by the two substrates 2 and 2. This substrate is made of glass or transparent synthetic resin.
The thickness of this substrate is usually 0.01 to 2.0 mm. In the present invention, a glass substrate is particularly preferable as this substrate.

Transparent electrodes 4, 4 are formed on the surfaces of the two substrates 2, 2 which are in contact with the liquid crystal material 3. The transparent electrode is usually made of ITO or the like. The thickness of this transparent electrode is typically 100-2000 Angstroms.
A liquid crystal compounding film (not shown) may be further formed on the transparent electrodes 4, 4. This liquid crystal alignment film can be formed by rubbing a polyimide resin.

The substrate having the transparent electrode and the liquid crystal alignment film formed on one surface as described above is arranged so that the transparent electrodes 4 face each other and form a constant gap. Transparent electrode 4,
The fixed gap formed between the four is normally formed using the spacer 5. As the spacer 5, for example, inorganic particles, inorganic fibers, resin particles, or a resin film formed in a predetermined pattern (for example, comb shape) can be used. The spacer may also serve as the liquid crystal alignment film.

The width of the gap thus formed is usually 1
10 to 10 μm. The two transparent substrates arranged with a gap as described above are usually bonded by sealing the periphery 6 with a sealing material. As the sealing material 6, an epoxy resin, a silicone resin, or the like can be used.

The liquid crystal 3 is filled in the gap formed as described above. As the liquid crystal 3 filled here, a Schiff base liquid crystal compound, an azoxy liquid crystal compound,
Examples thereof include benzoic acid ester liquid crystal compounds, cyclohexylcarboxylic acid ester liquid crystal compounds, phenyl liquid crystal compounds, terphenol liquid crystal compounds, cyclohexyl liquid crystal compounds, and pyrimidine liquid crystal compounds. These liquid crystal compounds can be used alone or in combination.

The liquid crystal element has the above-mentioned constitution, and the liquid crystal element of the present invention uses a specific adhesive composition on the outer surface of the above-mentioned substrate to form a polarizing plate or a phase difference with the polarizing plate. Laminated boards 7, 7'with boards are attached.

The polarizing plate used here is, for example, a polyester film, a polyvinyl alcohol resin film,
It can be manufactured by dyeing a resin film such as a polyvinyl butyral resin film with iodine or a dichroic dye, stretching it uniaxially, and laminating a protective film such as a triacetate film from both sides.

The polarizing plate or the laminated plates 7 and 7'of the polarizing plate and the retardation plate are attached to the surface of the substrate 2 as follows.
First, a laminated plate 7 or 7'of a polarizing plate or a polarizing plate and a retardation plate
A polarizing plate or a laminated plate of the polarizing plate and the retardation plate is adhered to the surface of the polarizing plate or the laminated plate of the polarizing plate and the retardation plate by using the pressure-sensitive adhesive composition for liquid crystal element described above. Then, the adhesive layers 8 and 8 are formed. The thickness of the adhesive layers 8, 8 thus formed is usually 10 to 50 μm, preferably 15 to 40 μm. By forming the adhesive layer with the above thickness, the substrate and the polarizing plate, or the substrate and the laminated plate of the polarizing plate and the retardation plate can be bonded with necessary and sufficient adhesive strength. At the same time, the adhesive layers 8 and 8 are transparent, and the optical characteristics of the liquid crystal element are not deteriorated by the adhesive layers.

The polarizing plate on which the adhesive layer 8 is thus formed or the laminated plate of the polarizing plate and the retardation plate is pressure-bonded to the outer surface of the substrate 2. If necessary, heating can be performed during this pressure bonding. By pressure-bonding in this manner, the pressure-sensitive adhesive composition for a liquid crystal device, which comprises a reactive oligomer and an acrylic polymer, and the substrate surface and the polarizing plate surface (or the laminated plate surface comprising the polarizing plate and the retardation plate) Adhesive strength of suitable strength is developed between and. The time required for this pressure bonding is, for example, about 10 to 30 minutes at 50 ° C. and 5 atmospheres.

By using the pressure-sensitive adhesive composition for liquid crystal elements of the present invention in this manner, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is adhered to the surface of the substrate with a suitable adhesive force. It becomes difficult for a gap to occur between the substrate and the polarizing plate, or between the substrate and the laminated plate of the polarizing plate and the retardation plate. Further, even if the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is peeled from the glass substrate, the adhesive does not remain on the glass substrate surface, and the glass substrate or the liquid crystal cell is damaged during the peeling. There is nothing to do.

Further, in the liquid crystal element of the present invention, the substrate and the polarizing plate or the laminated plate of the polarizing plate and the retardation plate are stably bonded for a long period of time, so that the substrate and the polarizing plate or the substrate and the polarizing plate are adhered to each other. It is possible to effectively prevent the performance of the liquid crystal element from being deteriorated due to poor adhesion between the retardation plate and the laminated plate.

[0068]

The pressure-sensitive adhesive composition for liquid crystal elements of the present invention comprises an acrylic copolymer (a) and a specific carboxylic acid compound and / or its derivative (b). By using the agent, the substrate and the polarizing plate or the laminated plate of the polarizing plate and the retardation plate can be bonded to each other with an adhesive strength necessary and sufficient for use in an environment where the liquid crystal element is actually used.

In addition, if this adhesive strength causes a problem in the adhesion in the liquid crystal element manufacturing process, the adhesive can be peeled off without leaving the adhesive component on the substrate. Alternatively, the liquid crystal cell is rarely damaged.

As described above, the pressure-sensitive adhesive composition for a liquid crystal element of the present invention is swellable or peeled off when the liquid crystal element is used under high temperature and high humidity conditions, although it is peelable in the manufacturing process. Is less likely to occur, and by using this adhesive, the liquid crystal element can be used for a long time under severe conditions.

Further, the liquid crystal element of the present invention has good adhesion between the glass substrate and the polarizing plate or the laminated plate of the polarizing plate and the retardation plate, and the adhesion state of both is stable for a long period of time. Therefore, the liquid crystal device of the present invention can maintain excellent optical characteristics for a long time.

[0072]

The present invention will be described in more detail below with reference to examples of the present invention, but the present invention should not be construed as limited by these examples.

In the following, "parts" means "parts by weight" unless otherwise specified.

[0074]

Example 1 25 parts of 2-ethylhexyl acrylate, n-
40 parts of butyl acrylate, 5 parts of styrene, 20 parts of ethyl acrylate, 8 parts of acrylic acid, 2 parts of 2-hydroxyethyl acrylate, 100 parts of toluene and 0.2 part of azobis (ishibutyronitrile) were placed in a reactor, and this reactor was used. After replacing the air inside with nitrogen gas, the temperature of this reaction solution was raised to 60 ° C. in a nitrogen atmosphere with stirring, and the reaction was carried out for 4 hours.

Separately, a solution was prepared by dissolving 0.4 part of azobisisobutyronitrile in 10 parts of toluene. After 4 hours, 10 parts of the thus-prepared solution of azobisisobutyronitrile was added dropwise to the reaction solution heated to 60 ° C. over 4 hours.

Further, this reaction solution was heated to 70 ° C., and 10 parts of a solution of azobisisobutyronitrile prepared in the same manner as above was added dropwise over 4 hours. 220 parts of a toluene solution of an acrylic polymer was obtained by operating as described above and polymerizing for a total of 12 hours. The concentration of the acrylic copolymer in this toluene solution is 4
It is 5% by weight.

220 parts of the above reaction liquid (corresponding to 100 parts by weight of the acrylic copolymer) had a phase transition temperature of 49.5 ° C.
5 parts of tetradecyl palmitate, which is an organic compound, and a polyisocyanate compound, which is a cross-linking agent (a polyisocyanate compound obtained by adding 1 mol of trimethylolpropane to 3 mol of tolylene diisocyanate, trade name: Coronate L, Nippon Polyurethane Co., Ltd.) 2 parts) and well stirred to obtain the adhesive composition of the present invention.

The adhesive composition obtained as described above was applied to a polyester release film and dried (adhesive composition dry coating thickness 25 μm). Then, the adhesive composition applied on the release film was coated with a thickness of
After transfer onto a 20 mm polarizing plate and aging for 7 days at a temperature of 23 ° C. and a humidity of 65%, the polarizing plate and the glass substrate are held at a temperature of 50 ° C. and a pressure of 5 kg / cm ² for 20 minutes. Glued.

According to JIS-Z-0237 and JIS-Z-0238, the adhesive strength between the polarizing plate and the glass substrate adhered in this way is determined as follows: a) Initial adhesive strength (adhesive strength after leaving at 23 ° C. for 1 hour) It was measured.

(A) The sample prepared in the same manner was left at 50 ° C. for 10 hours, and then the adhesive strength was measured under the temperature condition. C) After the sample prepared in the same manner was left at 80 ° C. for 10 hours, the adhesive strength was measured under the temperature condition.

D) Furthermore, the sample prepared in the same manner was
After leaving it at 0 ° C. for 10 hours, it was left to cool to 23 ° C. and left at this temperature for 1 hour to measure the adhesive strength. The higher the adhesive strength of (a) than the adhesive strength of (a) and the higher adhesive strength of (c) than the adhesive strength of (a), the polarizing plate or the polarizing plate and the retardation film attached to the liquid crystal element substrate. No peeling or foaming occurs even when the laminate is exposed to a more severe environment. Further, the smaller the difference in the adhesive strength between a) and d), the better the removability. Furthermore, when the adhesive strengths of a) and d) were measured, the residual property (residual residue) of the adhesive on the surface of the glass substrate was visually observed and evaluated.

Also, 20 samples prepared in the same manner were used.
Cut into 30 cm ² and adhere under the above conditions, 100 ℃
The condition of occurrence of foaming and peeling under the conditions of 500 hours at 60 ° C. and 90% RH was visually observed and evaluated.

The results are shown in Table 1. The liquid crystal device in which the polarizing plate prepared as described above was attached to the surface showed good characteristics.

[0084]

Comparative Example 1 Using the adhesive composition prepared as described above except that the amount of tetradecyl palmitate added in Example 1 was changed to 0.1 part, the properties of the adhesive composition were the same as in Example 1. Was evaluated.

The results are shown in Table 1.

[0086]

Comparative Example 2 In the same manner as in Example 1, except that the amount of tetradecyl palmitate added in Example 1 was changed to 40 parts, the characteristics of the adhesive composition were evaluated in the same manner as in Example 1. did.

The results are shown in Table 1.

[0088]

Comparative Example 3 An adhesive composition was obtained in the same manner as in Example 1, except that the organic compound was not added.

Using the adhesive composition produced as described above, its characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0090]

Comparative Example 4 An adhesive composition was obtained in the same manner as in Example 1 except that 5 parts of stearyl stearate having a phase transition temperature of 60 ° C. was added instead of adding tetradecyl palmitate.

As a result, the molded sample was heated at 23 ° C. and 50 ° C.
The adhesive layer becomes white at any temperature of 80 ° C and 80 ° C.
It was found that the stearyl stearate was not dissolved in the acrylic polymer even in a high temperature range above the phase transition temperature of the additive.

Using the adhesive composition produced as described above, its characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0093]

[Table 1]

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a liquid crystal element of the present invention.

[Explanation of symbols]

1 ... Liquid crystal element 2 ... Substrate 3 ... Liquid crystal material 4 ... Transparent electrode 5 ... Spacer 6 ... Sealing material 7, 7 '... Polarizing plate Laminated plate with phase difference plate 8 ... Adhesive layer

Claims (8)

[Claims] 1. A (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms (50 to 9).
A copolymer of 9.9% by weight, 0.1 to 10% by weight of an ethylenically unsaturated monomer having a polar group in the molecule, and 0 to 49.9% by weight of a monomer copolymerizable therewith, and ( b) Phase transition temperature from solid phase to liquid phase is 25 to 85
The organic compound is in the range of 0 ° C. and is at least partially soluble in the copolymer (a) at the phase transition temperature or higher, and the organic compound (b) is 100 parts by weight of the copolymer (a). A pressure-sensitive adhesive composition for liquid crystal devices, characterized in that it is contained in an amount of 0.5 to 20 parts by weight based on parts. 2. The organic compound (b) has a molecular weight of 200.
1. It is within the range of -5000.
A pressure-sensitive adhesive composition for a liquid crystal device according to the item. 3. The organic compound (b) is a carboxylic acid compound and / or a derivative thereof, and the derivative of the carboxylic acid compound is an ester compound derived from an alcohol having 4 to 24 carbon atoms and a carboxylic acid compound, An ester compound of a fatty acid having 4 to 24 carbon atoms and an alcohol,
The reaction product of a fatty acid having 4 to 24 carbon atoms and an amino compound, and a compound selected from the group consisting of a polymer of the carboxylic acid compound and / or its derivative. The pressure-sensitive adhesive composition for liquid crystal devices according to item 2. 4. The pressure-sensitive adhesive composition for a liquid crystal device contains 15 parts by weight or less of a cross-linking agent with respect to 100 parts by weight of the copolymer (a). The pressure-sensitive adhesive for liquid crystal devices according to any one of item 3. 5. A liquid crystal device in which a liquid crystal is filled in a gap formed by two substrates in which a polarizing plate or a laminated plate of a polarizing plate and a retardation plate is arranged on the surface of the substrate. In addition, the polarizing plate or the laminated plate of the polarizing plate and the retardation plate is (a) 50 to 99.9% by weight of (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms.
A copolymer of 0.1 to 10% by weight of an ethylenically unsaturated monomer having a polar group in the molecule and 0 to 49.9% by weight of a monomer copolymerizable therewith, and (b) from a solid phase Phase transition temperature to liquid phase is 25-85
The organic compound is in the range of 0 ° C. and is at least partially soluble in the copolymer (a) at the phase transition temperature or higher, and the organic compound (b) is 100 parts by weight of the copolymer (a). A liquid crystal device, wherein the pressure-sensitive adhesive composition for liquid crystal device is contained in an amount of 0.5 to 20 parts by weight based on 100 parts by weight. 6. The organic compound (b) has a molecular weight of 200.
6. It is within the range of -5000.
The liquid crystal element according to the item. 7. The organic compound (b) is a carboxylic acid compound and / or a derivative thereof, and the derivative of the carboxylic acid compound is an ester compound derived from an alcohol having 4 to 24 carbon atoms and a carboxylic acid compound, An ester compound of a fatty acid having 4 to 24 carbon atoms and an alcohol,
6. A reaction product of a fatty acid having 4 to 24 carbon atoms and an amino compound, and a compound selected from the group consisting of polymers of the carboxylic acid compound and / or its derivative, 6. A liquid crystal device according to item 6. 8. The pressure-sensitive adhesive composition for a liquid crystal device contains 15 parts by weight or less of a cross-linking agent based on 100 parts by weight of the copolymer (a). Item 7. The liquid crystal device according to any one of items 7.