JPH05216049A - Spacer for liquid crystal display and production thereof - Google Patents

Abstract

PURPOSE:To prevent the damage of poly imide oriented films having excellent adhesiveness to electrode panel surfaces and to optimize the spacers as the spacers for liquid crystal display by constituting the spacers of crosslinked polymer particulates having specific functional groups. CONSTITUTION:The spacers are constituted of the crosslinked polymer particulates having at least one kind of the functional groups selected from an epoxy group, amino group, hydroxyl group, amide group and carboxyl group on the surface. A polymerizable monomer, crosslinkable monomer and polymn. initiator having at least one of the functional groups selected from the epoxy group, amino group, hydroxyl group, amide group and carboxyl group as the substituent within the molecule at <90% reaction rate are preferably added to the crosslinked polymer particulates and are subjected to a copolymn. at the time of producing the crosslinked polymer particulates. The crosslinkable monomer is exemplified by a styrene monomer, acrylate monomer, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel spacer for liquid crystal display and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
In a liquid crystal display panel, predetermined inorganic or organic particles are used as a liquid crystal display spacer in order to maintain the parallelism of the panel. The performance required as a spacer for a liquid crystal display panel includes 1) a narrow particle size distribution, 2) sufficient strength, and 3) good adhesion to the liquid crystal panel surface. Regarding particle size distribution and strength,
This is a basic required performance as a liquid crystal display spacer. Also, the reason why the adhesiveness to the liquid crystal panel surface is necessary is that when the spacer moves in the liquid crystal when the panel is created, the polyimide alignment film on the electrode panel surface is damaged,
It can be mentioned that the liquid crystal alignment in that portion is disturbed.

Regarding the particle size distribution and strength among these performances, various methods have been tried and have reached almost satisfactory levels. Regarding the method of improving the adhesion to the liquid crystal panel surface, what is called a hot-melt resin coating is disclosed (JP-A-52-29754 and JP-A-58-102922).
No. 59-218425, No. 63-94224).
Due to problems such as particle aggregation and poor dispersion in the dispersion medium, satisfactory performance has not been obtained.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies as to a spacer for a liquid crystal display which solves the above-mentioned drawbacks of the prior art and has excellent adhesion to the electrode panel surface. It was found that the adhesion to a polyimide film is remarkably improved by introducing at least one kind of functional group selected from epoxy group, amino group, hydroxyl group, amide group and carboxyl group on the surface, and the present invention is completed. I arrived. That is, the present invention, the surface of the epoxy group,
The present invention provides a liquid crystal display spacer comprising a crosslinked polymer fine particle having at least one kind of functional group selected from an amino group, a hydroxyl group, an amide group and a carboxyl group, and a method for producing the same.

To obtain the spacer for liquid crystal display of the present invention, an epoxy group, an amino group,
It is necessary to introduce at least one kind of functional group selected from a hydroxyl group, an amide group and a carboxyl group, and in order to achieve this, the following three kinds of methods can be mentioned. (1) As an essential component, a polymerizable monomer having at least one functional group selected from an epoxy group, an amino group, a hydroxyl group, an amide group, and a carboxyl group as a substituent in the molecule.
Polymerization method using (A). (2) When producing crosslinked polymer fine particles, the reaction rate is 90%.
%, The polymerizable monomer (A), the crosslinkable monomer and the polymerization initiator are added to carry out copolymerization. (3) A method in which the polymerizable monomer (A), the crosslinkable monomer and the polymerization initiator are adsorbed or absorbed on the surface or inside of the crosslinked polymer fine particles, and then the polymerization is performed.

These methods will be described in detail below. The first method is the polymerizable monomer (A) having the above functional group [eg, epoxy group: glycidyl (meth) acrylate, divinylbenzene monoxide, p-glycidylstyrene, p-glycidyl-α-methylstyrene]. ,
Allyl glycidyl ether, etc., amino group: dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, p-aminostyrene, etc., hydroxyl group: hydroxyethyl (meth) acrylate, hydroxypropyl (meth) Acrylate, glycerol mono (meth)
Acrylate, etc., amide group: acrylamide, isopropylacrylamide, dimethylaminopropylacrylamide, etc., carboxyl group: (meth) acrylic acid, maleic acid, etc.] and styrene, p-methylstyrene, p-chlorostyrene, pt-butoxystyrene Styrene-based monomers such as, and (meth) acrylate (meth) acrylate-based monomers such as ethyl (meth) acrylate,
Vinyl monomers such as vinyl acetate and vinyl chloride, divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, methylenebisacrylamide,
It is a method of polymerizing a crosslinkable monomer such as divinyloxybutane by a method such as suspension polymerization and seed polymerization, but the method is not limited to these monomers, and two or more kinds of monomers It is possible to mix and use.

Further, as another production method of the first method, an epoxy group is obtained by alkali treatment of fine particles of a crosslinked polymer having a halohydrin derivative such as 3-chloro-2-hydroxypropyl (meth) acrylate as a constituent monomer. Introduction, introduction of an amino group by reacting ethylenediamine, triethylenetetramine or the like with respect to the crosslinked polymer fine particles having an epoxy group and a carboxyl group, p-
Introduction of hydroxyl groups by hydrolysis of fine particles of cross-linked polymer such as t-butoxystyrene, introduction of carboxyl groups by hydrolysis of fine particles of (meth) acrylic acid ester-based cross-linked polymers such as methyl (meth) acrylate and ethylene glycol dimethacrylate Alternatively, a method of chemically treating the crosslinked polymer fine particles to introduce a functional group can also be used. Furthermore, for crosslinked polymer fine particles having an epoxy group and a carboxyl group, modified polyethylene glycol {epoxy modified: epoxy PEG # 400, 100 [SR-8EG, SR
-2EG [Sakamoto Yakuhin Kogyo Co., Ltd.], amino modified: PE
The spacer for liquid crystal display of the present invention can also be obtained by a method of reacting O # 400 amine and PEO # 6000 amine [produced by Kawaken Fine Chemicals Co., Ltd.].

The second method is styrene / divinylbenzene, styrene / ethylene glycol dimethacrylate,
Styrene-based cross-linking polymers such as styrene / butadiene; methyl (meth) acrylate / divinylbenzene, methyl (meth) acrylate / ethylene glycol dimethacrylate, methyl (meth) acrylate / methylene bisacrylamide, etc. (meth) acrylate cross-linking Polymer; ethylene / butadiene, methyl vinyl ether /
When producing fine particles of a known crosslinked polymer such as an olefinic crosslinked polymer such as divinyloxybutane, vinyl acetate / divinyloxybutane, vinyl chloride / divinylbenzene, etc., when the polymerization rate is less than 90%, Is a method in which the polymerizable monomer (A) having the functional group (1), the crosslinkable monomer and the polymerization initiator are added to carry out copolymerization. At this time, as the crosslinkable monomer, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate,
Examples include polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and divinyloxybutane. As a method for adding a monomer mixture containing these polymerizable monomers (A), the monomer mixture is added as it is or dispersed in a surfactant aqueous solution such as sodium lauryl sulfate by a homomixer or the like. It may be added as an emulsion.

Even if the above-mentioned monomer (A) having a functional group is added when the polymerization rate of the polymer fine particles exceeds 90%, the effect of the present invention is difficult to obtain, and the shape of Particles may be generated, which is not preferable. The polymerization rate was determined by the following weight method. That is, a constant weight of a dispersion liquid is sampled from a polymerization tank during synthesis of crosslinked polymer fine particles, and dispersed in a large amount of methanol (containing 1000 ppm of hydroquinone monomethyl ether). The obtained precipitate was isolated by a method such as filtration or centrifugation, dried under reduced pressure, and the polymerization rate was calculated by the following formula. Here, the weight of the monomer (g) in the polymerization dispersion is the weight of the dispersion sampled (g) × concentration of the charged monomer (%).

[0010]

[Equation 1]

The third method is styrene / divinylbenzene, styrene / ethylene glycol dimethacrylate,
Styrene-based cross-linking polymers such as styrene / butadiene; methyl (meth) acrylate / divinylbenzene, methyl (meth) acrylate / ethylene glycol dimethacrylate, methyl (meth) acrylate / methylene bisacrylamide, etc. (meth) acrylate cross-linking Polymer; ethylene / butadiene, methyl vinyl ether /
Polymerizable monomer having the above functional group for fine particles composed of known cross-linked polymers such as olefin cross-linked polymers such as divinyloxybutane, vinyl acetate / divinyloxybutane, vinyl chloride / divinylbenzene (A) is a method in which after impregnating the crosslinkable monomer and the initiator, further polymerization is performed.

The addition amount of the above-mentioned polymerizable monomer (A) and crosslinkable monomer to the crosslinked polymer fine particles depends on the solubility of these monomers in water, but generally, About 5 to 500 parts by weight is preferable to 50 parts by weight of the combined fine particles.
If the amount is less than 5 parts by weight, sufficient adhesion cannot be imparted, and if the amount is more than 500 parts by weight, problems such as aggregation of the polymerization system may occur, which is not preferable.

As the solvent used for this impregnation treatment, a solvent in which these monomers are soluble but the crosslinked polymer fine particles are insoluble may be used. Among them, a solvent that expands the crosslinked polymer fine particles is more preferable. For example, tetrachloroethane,
Dichloroethane, toluene, DMF (dimethylformamide), DMSO (dimethylsulfoxide), THF
A solvent such as (tetrahydrofuran) is more preferably used, and the impregnation treatment is performed at a temperature of room temperature to about 40 ° C. Also,
Disperse / dissolve the crosslinked polymer particles, the polymerizable monomer (A), the crosslinkable monomer and the polymerization initiator in a solvent such as methanol or ethanol, and distill the solvent under reduced pressure at room temperature to 40 ° C. Alternatively, the impregnation treatment may be performed.

In the above method of mixing the polymerization initiator and the monomer and impregnating the fine particles of the crosslinked polymer, known polymers soluble in these solvents, such as polyvinyl alcohol, polytetrahydrofuran, polyethylene oxide, Propylene oxide, ethyleneimine, polyvinylpyrrolidone, poly (N-ethyleneimine), etc. may be added. Further, the solvent used for the polymerization after the impregnation treatment is not particularly limited as long as the polymerizable monomer (A) and the crosslinkable monomer are insoluble, for example, water to which an inorganic salt is added, Aliphatic hydrocarbon solvents such as hexane and cyclohexane are used. In the polymerization step, various surfactants or protective colloids may be used in order to improve the dispersion stability of the polymer particles.

When the crosslinked polymer fine particles of the present invention are obtained by the polymerization reaction by the above-mentioned three methods, the polymerizable monomer (A) is added as a constituent component for the purpose of enhancing the effect of the present invention. It may be added by a method such as mixing the polymer with a polymerization dispersant. Further, the crosslinked polymer fine particles of the present invention may be immersed in a solvent containing a polymer containing the polymerizable monomer (A) as a constituent at a temperature of room temperature to about 150 ° C.

In the above-mentioned three methods, the monomers to be the constituent units of the crosslinked polymer particles can be used alone or in combination of two or more. The weight ratio of the polymerizable monomer (A) having the functional group to the monomer having no functional group and the crosslinkable monomer is preferably 1/99 to 70/30. The ratio of the monomer (A) having a functional group is 1
When the amount is less than 70% by weight, the amount of the functional group is small and the effect of the present invention is small, and when the amount is more than 70% by weight, the ratio of the crosslinkable monomer in the crosslinked polymer fine particles is inevitably inevitable. As a result, the particle strength is not sufficient, and when incorporated into a liquid crystal display panel, it causes color unevenness during display, which is not preferable.

As the polymerization initiator that can be used in the present invention, generally used oil-soluble polymerization initiators can be used. For example, benzoyl peroxide, lauroyl peroxide, o
-Peroxide initiators such as benzoyl chloroperoxide, benzoyl o-methoxyperoxide, etc. Azo such as 2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethylvaleronitrile) Initiators can be used.

Further, the average particle diameter of these crosslinked polymer fine particles varies depending on the purpose and the type of liquid crystal display panel, but is usually about 2 to 10 μm. When the crosslinkable polymer fine particles having a wide particle size distribution are incorporated in the liquid crystal display panel, the distance between the two transparent electrodes in the panel cannot be kept constant, and the cause of color unevenness at the time of display. Therefore,
The standard deviation of the particle size distribution is preferably 20% or less of the particle size.

When the spacer for liquid crystal display of the present invention is sprayed on the polyimide alignment film by a method commonly used (wet and dry spraying), sufficient adhesion to the polyimide alignment film can be obtained. The effect of the present invention can be further enhanced by heating at 100 to 200 ° C. for 30 minutes to 1 hour. However, in the process of assembling the liquid crystal panel, 10
No special consideration is required because it includes a step of heating and curing the sealant at 0 to 200 ° C.

[0020]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. In addition, a part shows a weight part in an Example.

Example 1 40 parts of glycidyl methacrylate (manufactured by Tokyo Kasei Co., Ltd.),
Polyvinyl alcohol (GH-17, manufactured by Nippon Synthetic Chemical Industry Co., Ltd .; saponification degree: 86.5) in a mixed solution of 60 parts of divinylbenzene (purity 55%) and 3 parts of benzoyl peroxide (manufactured by NOF CORPORATION, Niper BW). ~ 89mol%) 3% aqueous solution 800
Parts were added and suspension polymerization was carried out at 80 ° C. for 10 hours under a nitrogen stream while stirring. The obtained fine particles were washed with ion-exchanged water and a solvent, and then classified to 6.2 μm with a standard deviation of 1.5 μm.
Thus, crosslinked polymer fine particles were obtained.

The resulting crosslinked polymer fine particles were evaluated for adhesion to liquid crystal panels by the following method. That is, 0.5 g of a liquid crystal display spacer previously dried under reduced pressure (40 ° C./24 hours) was weighed, and Freon S3-E (manufactured by Daikin Industries, Ltd.) / Isopropanol (Wako Pure Chemical Industries, Ltd.)
Manufactured) = 3/2 (v / v) dispersed in 50 ml of mixed solvent. A polyimide film (manufactured by Nissan Chemical Industries, Ltd.)-Glass was immersed therein for 10 seconds, and the dispersion medium was evaporated at room temperature for 5 minutes. This test piece was heat-treated with a warm air dryer at 170 ° C. for 1 hour. Further, after measuring the number of liquid crystal display spacers within a predetermined visual field with an optical microscope, an air gun (3 kg / cm ² , hole diameter 1
Air was blown onto the glass plate for 10 seconds at a distance of 29 mm), and the number of liquid crystal display spacers within a predetermined visual field was measured again. The residual rate was calculated from the change in the number before and after spraying, and the adhesiveness was evaluated. When the adhesiveness was evaluated by this method, the spacer for liquid crystal display showed a residual rate of 97.5%.

Example 2 10 parts of methacrylic acid (manufactured by Tokyo Kasei), 10 parts of ethylene glycol dimethacrylate (manufactured by Tokyo Kasei), 80 parts of divinylbenzene (purity 55%), peroxide as a polymerization initiator Benzoyl (NIPPER BW) 3
Part is used for suspension polymerization, and classification is performed to obtain an average particle size.
Crosslinked polymer microparticles having a size of 6.9 μm and a standard deviation of 1.3 μm were obtained. The obtained fine particles were washed with ion-exchanged water and a solvent and then isolated and dried to obtain crosslinked polymer fine particles. When the adhesion was evaluated in the same manner as in Example 1, this liquid crystal display spacer showed a residual rate of 90.8%.

Example 3 10 parts of the crosslinked polymer fine particles obtained in Example 2 were mixed with 10 parts of toluene.
Dispersed in 0 parts, ethylenediamine (Tokyo Kasei Co., Ltd.)
(Manufactured by Mfg. Co., Ltd.) was added and the mixture was reacted under reflux for 24 hours. The obtained fine particles were dispersed / washed in chloroform, further washed with methanol, and then isolated and dried to obtain a spacer for liquid crystal display. When the adhesion was evaluated in the same manner as in Example 1, this liquid crystal display spacer showed a residual rate of 92.9%.

Example 4 Hydroxyethyl methacrylate (manufactured by Tokyo Kasei Co., Ltd.)
20 parts, ethylene glycol dimethacrylate (Tokyo Kasei Co., Ltd.) 10 parts, divinylbenzene (purity 55%) 70 parts,
Benzoyl peroxide as a polymerization initiator (NOF Corporation)
(Manufactured by Niper BW), suspension polymerization was carried out, and classification was carried out to obtain crosslinked polymer fine particles having an average particle diameter of 10 μm and a standard deviation of 1.8 μm. The obtained fine particles were washed with ion-exchanged water and a solvent and then isolated and dried to obtain crosslinked polymer fine particles. When the adhesion was evaluated in the same manner as in Example 1, this liquid crystal display spacer showed a residual rate of 92.6%.

Example 5 Isopropylacrylamide (manufactured by Tokyo Kasei Co., Ltd.) 40
Department, Methylenebisacrylamide (manufactured by Tokyo Kasei Co., Ltd.)
Suspension polymerization was carried out using 30 parts, 30 parts of divinylbenzene (purity 55%), and 1.0 part of 2,2-azobisisobutyronitrile as a polymerization initiator, and classification was performed to obtain an average particle size of 5.9 μm.
A crosslinked polymer fine particle having a standard deviation of 1.1 μm was obtained. After washing the obtained fine particles with ion-exchanged water and a solvent,
It was isolated and dried to obtain crosslinked polymer particles. When the adhesion was evaluated in the same manner as in Example 1, this liquid crystal display spacer showed a residual rate of 90.6%.

Example 6 Styrene 40 parts, divinylbenzene (purity 55%) 60 parts 2,
To a mixed solution of 1.0 part of 2-azobisisobutyronitrile, a 3% aqueous solution of polyvinyl alcohol (GH-17, manufactured by Nippon Synthetic Chemical Industry Co., Ltd .; saponification degree: 86.5 to 89 mol%) 800
Parts were added, and polymerization was carried out at 80 ° C. for 1 hour under a nitrogen stream while stirring. When the polymerization rate at this time was determined by the gravimetric method,
It was 32.7%. 2,2-azobisisobutyronitrile 1.0 part, ethylene glycol dimethacrylate 10 parts, glycidyl methacrylate (Tokyo Kasei Co., Ltd.)
(Manufactured by Mitsui Chemicals Co., Ltd.), 40 parts, 1.5 parts of sodium lauryl sulfate, and 200 parts of ion-exchanged water were added to the mixture, and an emulsion was added to the mixture. The obtained fine particles are washed with ion-exchanged water and a solvent, subjected to classification operation, further isolated and dried, and have an average particle size of 7.
A liquid crystal display spacer having a size of 2 μm and a standard deviation of 1.4 μm was obtained. When the adhesion was evaluated in the same manner as in Example 1, this liquid crystal display spacer showed a residual rate of 90.2%.

Example 7 Suspension polymerization was carried out using 50 parts of styrene and 50 parts of divinylbenzene (purity 55%), and classification was carried out to obtain an average particle size of 10 μm.
Thus, crosslinked polymer fine particles having a standard deviation of 1.8 μm were obtained.

5 parts of the obtained crosslinked polymer fine particles were added to DMF20.
Parts, 2,2-azobisisobutyronitrile 0.18
Part, 2 parts of ethylene glycol dimethacrylate, and 10 parts of glycidyl methacrylate (manufactured by Tokyo Kasei Co., Ltd.) are added.
The mixture was stirred for 15 hours at 0 ° C. to impregnate the initiator, the polymerizable monomer (A), and the crosslinkable monomer. This solution was filtered, the obtained polymer was redispersed in 450 parts of cyclohexane, and 0.45 part of Rheidol SP-S10 (manufactured by Kao Corporation, nonionic surfactant) was added, and polymerization was carried out at 62 ° C. for 15 hours. The monomer was polymerized. The obtained fine particles were washed with ion-exchanged water and a solvent and then isolated and dried to obtain a liquid crystal display spacer. Example 1
When the adhesiveness was evaluated by the same method as described above, this spacer for liquid crystal display showed a residual rate of 93.6%.

Example 8 Suspension polymerization was carried out using 60 parts of styrene and 40 parts of divinylbenzene (purity 55%), and classification was carried out to obtain an average particle size of 7.2 μm.
Crosslinked polymer fine particles having m 2 and standard deviation of 1.3 μm were obtained. 5 parts of the obtained crosslinked polymer fine particles were dispersed in 20 parts of DMF, and 0.5 part of 2,2-azobisisobutyronitrile, 5 parts of triallyl isocyanurate, and 20 parts of allyl glycidyl ether (manufactured by Tokyo Kasei Co., Ltd.). The mixture was stirred at 35 ° C. for 15 hours to impregnate the initiator, the polymerizable monomer (A), and the crosslinkable monomer. This solution was filtered, and the obtained polymer was redispersed in 450 parts of cyclohexane to give Rheidol SP-S10.
(Kao Corporation, nonionic surfactant) 0.45 parts was added.
The polymerizable monomer was polymerized at 62 ° C for 15 hours. The obtained fine particles were washed with ion-exchanged water and a solvent and then isolated and dried to obtain a liquid crystal display spacer. When the adhesion was evaluated in the same manner as in Example 1, this liquid crystal display spacer showed a residual rate of 92.5%.

Example 9 Dimethylaminoethyl methacrylate (Tokyo Kasei Co., Ltd.)
35 parts), ethylene glycol dimethacrylate (Tokyo Kasei Co., Ltd.) 30 parts, divinylbenzene (purity 55%) 35
Parts, suspension polymerization was carried out using 5.0 parts of 2,2-azobisisobutyronitrile as a polymerization initiator, and classification was performed to obtain crosslinked polymer fine particles having an average particle size of 8.2 μm and a standard deviation of 1.5 μm. It was The obtained fine particles were washed with ion-exchanged water and a solvent and then isolated and dried to obtain crosslinked polymer fine particles. When the adhesion was evaluated in the same manner as in Example 1,
This liquid crystal display spacer showed a residual rate of 90.8%.

Comparative Example 1 The styrene-based crosslinked polymer fine particles obtained in Example 8 were evaluated for adhesion without the impregnation treatment as described above, and as a result, only a residual rate of 4.8% was shown.

[0033]

As is clear from the results of the above examples, the liquid crystal display spacer obtained by the present invention has excellent adhesion to the electrode panel surface. Therefore, the polyimide alignment film can be prevented from being damaged, and it is suitable as a spacer for a liquid crystal display.

Claims (4)

[Claims] 1. An epoxy group, an amino group, a hydroxyl group on the surface,
A spacer for a liquid crystal display, comprising crosslinked polymer fine particles having at least one kind of functional group selected from an amide group and a carboxyl group. 2. A polymerizable monomer (A) having at least one functional group selected from the group consisting of an epoxy group, an amino group, a hydroxyl group, an amide group and a carboxyl group as a substituent in the molecule is used as an essential component for polymerization. The method for manufacturing a spacer for a liquid crystal display according to claim 1, wherein 3. When producing a crosslinked polymer fine particle, when the reaction rate is less than 90%, at least a functional group selected from an epoxy group, an amino group, a hydroxyl group, an amide group and a carboxyl group is contained in the molecule as a substituent. The method for producing a spacer for a liquid crystal display according to claim 1, wherein the polymerizable monomer (A) having one, the crosslinkable monomer and the polymerization initiator are added and copolymerized. 4. The surface or inside of the crosslinked polymer fine particles,
Epoxy group, amino group, hydroxyl group as a substituent in the molecule,
An amide group, a polymerizable monomer having at least one functional group selected from a carboxyl group (A), the cross-linking monomer and the polymerization initiator is adsorbed or absorbed, followed by polymerization Item 2. A method of manufacturing a liquid crystal display spacer according to item 1.