JP3234267B2 - Liquid crystal display spacer and method of manufacturing the same - Google Patents

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 a liquid crystal display and a method for producing the same.

[0002]

2. Description of the Related Art
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 required performance of the spacer for a liquid crystal display panel includes 1) a narrow particle size distribution, 2) sufficient strength, and 3) good adhesion to a liquid crystal panel surface. Regarding particle size distribution and strength,
This is the 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 during panel production, the polyimide alignment film on the electrode panel surface is damaged,
That is, the liquid crystal alignment at that portion is hindered.

[0003] Among these properties, various methods have been tried with regard to particle size distribution and strength, and have reached almost satisfactory levels. Further, with respect to a method for improving the adhesion to the liquid crystal panel surface, a method of coating a so-called hot melt resin is disclosed (JP-A-52-29754 and JP-A-58-102922).
Nos. 59-218425 and 63-94224).
There were problems such as agglomeration of particles and poor dispersion in a dispersion medium, and satisfactory performance was not obtained.

[0004]

The present inventors have made intensive studies on a liquid crystal display spacer which has solved the above-mentioned disadvantages of the prior art and has excellent adhesion to the electrode panel surface. At least hydroxyl group and carboxyl on the surface
It has been found that by introducing at least one functional group selected from the groups , the adhesion to the polyimide film is significantly improved, and the present invention has been completed. That is, the present invention is a polymerization reaction using a polymerizable monomer (A) having at least one functional group selected from a hydroxyl group and a carboxyl group as a substituent in a molecule and having no epoxy group as an essential component. Provided are a spacer for liquid crystal display, characterized by comprising crosslinked polymer fine particles having at least one type of functional group selected from a hydroxyl group and a carboxyl group on the surface and having no epoxy group, and a method for producing the same. Things.

[0005] In order to obtain a liquid crystal display spacers of the present invention, amino groups on the surface of the crosslinked polymer fine particles, a hydroxyl group, an amido group, it is necessary to introduce at least one functional group selected from a carboxyl group To achieve this,
The following three methods can be given. (1) as an essential component, as a substituent in the molecule amino groups,
A method of performing polymerization using a polymerizable monomer (A) having at least one functional group selected from a hydroxyl group, an amide group, and a carboxyl group. (2) When producing crosslinked polymer fine particles, the reaction rate is 90%
% Of the polymerizable monomer (A), a crosslinkable monomer and a polymerization initiator. (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 carried out.

[0006] These methods will be described in detail below. In the first method, the polymerizable monomer (A) having the above functional group (for example , an 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 monomers such as styrene, p-methylstyrene, p-chlorostyrene and pt-butoxystyrene, and (meth) acrylate esters such as methyl (meth) acrylate and ethyl (meth) acrylate. Monomers, vinyl monomers such as vinyl acetate and vinyl chloride, and crosslinkable monomers such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, methylenebisacrylamide, and divinyloxybutane. It is a method in which the monomer is polymerized by a method such as suspension polymerization or seed polymerization, but is not limited to these monomers, and it is possible to use a mixture of two or more monomers. is there.

Further, as another production method of the first method, introduction of an amino group by reacting ethylenediamine, triethylenetetramine or the like with a crosslinked polymer fine particle having an epoxy group and a carboxyl group,
Introduction of hydroxyl groups by hydrolysis of crosslinked polymer fine particles such as t-butoxystyrene, introduction of carboxyl groups by hydrolysis of (meth) acrylate crosslinked polymer fine particles such as methyl (meth) acrylate and ethylene glycol dimethacrylate, etc. Alternatively, a method of chemically treating crosslinked polymer fine particles to introduce a functional group can also be used. Further, the crosslinked polymer fine particles having an epoxy group and a carboxyl group are modified with modified polyethylene glycol @ amino
The spacer for liquid crystal display of the present invention can also be obtained by a method of reacting PEO # 400 amine and PEO # 6000 amine (manufactured by Kawaken Fine Chemical Co., Ltd.).

[0008] The second method is styrene / divinylbenzene, styrene / ethylene glycol dimethacrylate,
Styrene-based crosslinked polymers such as styrene / butadiene; (meth) acrylate-based crosslinks such as methyl (meth) acrylate / divinylbenzene, methyl (meth) acrylate / ethylene glycol dimethacrylate, and methyl (meth) acrylate / methylenebisacrylamide Polymer; ethylene / butadiene, methyl vinyl ether /
When producing fine particles comprising a known crosslinked polymer such as an olefinic crosslinked polymer such as divinyloxybutane, vinyl acetate / divinyloxybutane, and vinyl chloride / divinylbenzene, when the polymerization rate is less than 90%, This is a method of adding a polymerizable monomer (A) having a functional group, a crosslinking monomer and a polymerization initiator to carry out copolymerization. At this time, as the crosslinking 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 of adding a monomer mixture containing these polymerizable monomers (A), the monomer mixture may be added as it is, or dispersed in an aqueous solution of a surfactant such as sodium lauryl sulfate using a homomixer or the like. It may be added as a prepared emulsion.

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

[0010]

(Equation 1)

A third method is to use styrene / divinylbenzene, styrene / ethylene glycol dimethacrylate,
Styrene-based crosslinked polymers such as styrene / butadiene; (meth) acrylate-based crosslinks such as methyl (meth) acrylate / divinylbenzene, methyl (meth) acrylate / ethylene glycol dimethacrylate, and methyl (meth) acrylate / methylenebisacrylamide Polymer; ethylene / butadiene, methyl vinyl ether /
A polymerizable monomer having the above functional group with respect to fine particles comprising a known crosslinked polymer such as an olefinic crosslinked polymer such as divinyloxybutane, vinyl acetate / divinyloxybutane, and vinyl chloride / divinylbenzene. (A) is a method of impregnating a crosslinkable monomer and an initiator and then performing polymerization.

The amount of the polymerizable monomer (A) and the crosslinkable monomer to be added to the crosslinked polymer fine particles depends on the solubility of these monomers in water. The amount is preferably about 5 to 500 parts by weight based on 50 parts by weight of the combined fine particles.
When the amount is less than 5 parts by weight, sufficient adhesion cannot be provided, and when the amount is more than 500 parts by weight, problems such as aggregation of the polymerization system tend to occur, which is not preferable.

As a solvent used in the impregnation treatment, a solvent in which these monomers are soluble and in which the crosslinked polymer fine particles are not dissolved 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 is performed at a temperature of room temperature to about 40 ° C. Also,
Disperse / dissolve the crosslinked polymer fine 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 a temperature of about room temperature to about 40 ° C. And may be impregnated.

In the above method of mixing a polymerization initiator and a monomer and impregnating the crosslinked polymer fine particles, a known polymer soluble in these solvents, for example, polyvinyl alcohol, polytetrahydrofuran, polyethylene oxide, Propylene oxide, ethyleneimine, polyvinylpyrrolidone, poly (N-ethyleneimine) and the like may be added. Further, the solvent used for 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 inorganic salts are added, Aliphatic hydrocarbon solvents such as hexane and cyclohexane are used. In the polymerization step, various surfactants or protective colloids may be used to improve the dispersion stability of the polymer particles.

When the crosslinked polymer fine particles of the present invention are obtained by a polymerization reaction according to the three methods described above, a polymer containing a polymerizable monomer (A) as a constituent component for the purpose of further enhancing the effects of the present invention. The union may be added by a method such as mixing with the 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) at a temperature of about room temperature to about 150 ° C.

In the three methods exemplified above, the monomers serving as constituent units of the crosslinked polymer fine particles can be used alone or in combination of two or more. The weight ratio of the polymerizable monomer (A) having a functional group to the monomer having no functional group and the crosslinkable monomer is preferably from 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 effect of the present invention is reduced because the amount of the functional group is reduced. When the amount exceeds 70% by weight, the proportion of the crosslinkable monomer in the crosslinked polymer fine particles is inevitably increased. As a result, the strength of the particles is not sufficient, and when the particles are incorporated into a liquid crystal display panel, they cause 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 chlorobenzoyl peroxide and o-methoxybenzoyl peroxide; azo compounds such as 2,2-azobisisobutyronitrile and 2,2-azobis (2,4-dimethylvaleronitrile) Initiators can be used.

The average particle size 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 cross-linkable polymer fine particles having a wide particle size distribution are incorporated in a liquid crystal display panel, the distance between two transparent electrodes in the panel cannot be kept constant, and color unevenness may occur during display. Because
It is preferable that the standard deviation of the particle size distribution is not more than 20% of the particle size.

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

[0020]

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

Example 1 10 parts of methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), ethylene glycol
Coal dimethacrylate (Tokyo Kasei Co., Ltd.) 10 parts,
80 parts of vinylbenzene (purity 55%) , excess as a polymerization initiator
Benzoyl oxide (Nipper BW, manufactured by NOF Corporation) 3
Perform suspension polymerization using a part and classify it to obtain an average particle size.
Crosslinked polymer microparticles with 6.9 μm and standard deviation 1.3 μm
I got Wash the obtained fine particles with ion exchanged water and solvent
Thereafter, the polymer was isolated and dried to obtain crosslinked polymer fine particles.

The resulting crosslinked polymer fine particles were evaluated for adhesion to a liquid crystal panel 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 (manufactured by Wako Pure Chemical Industries, Ltd.)
) = 3/2 (v / v) Disperse in 50 ml of a 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. The test piece was subjected to a heating treatment at 170 ° C./1 hour using a hot air drier. 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 , a hole diameter of 1
(mm, distance 29 mm) was blown onto the glass plate for 10 seconds, and the number of liquid crystal display spacers within a predetermined field of view was measured again. The residual ratio was calculated from the change in the number before and after spraying, and the adhesion was evaluated. When the adhesion was evaluated by this method, this liquid crystal display spacer showed a residual rate of 90.8% .

Example 2 10 parts of the crosslinked polymer fine particles obtained in Example 1 were
0 parts of ethylenediamine (Tokyo Kasei Co., Ltd.)
10 parts) and reacted under reflux for 24 hours. The obtained fine particles were dispersed / washed in chloroform, 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 ratio of 92.9%.

Example 3 Hydroxyethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)
20 parts, 10 parts of ethylene glycol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 70 parts of divinylbenzene (purity 55%),
Benzoyl peroxide as a polymerization initiator (Nippon Oil & Fats Co., Ltd.)
Polymerization, Niper BW, Inc., 3 parts, and subjected to a classification operation to obtain crosslinked polymer fine particles having an average particle size 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 4 Isopropylacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) 40
Part, methylenebisacrylamide (Tokyo Kasei Co., Ltd.)
Suspension polymerization was carried out using 30 parts of divinylbenzene (purity 55%), 30 parts of 2,2-azobisisobutyronitrile as a polymerization initiator, and 1.0 parts of 2,2-azobisisobutyronitrile.
Thus, crosslinked polymer fine particles having a standard deviation of 1.1 μm were obtained. After washing the obtained fine particles with ion-exchanged water and a solvent,
It was 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 90.6%.

Example 5 Dimethylaminoethyl methacrylate (Tokyo Kasei Co., Ltd.)
35 parts, ethylene glycol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) 30 parts, divinylbenzene (purity 55%) 35
, Suspension polymerization using 5.0 parts of 2,2-azobisisobutyronitrile as a polymerization initiator, and performing classification operation to obtain crosslinked polymer fine particles having an average particle size of 8.2 μm and a standard deviation of 1.5 μm. 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 ratio of 90.8%.

Comparative Example 1 60 parts of styrene and 40 parts of divinylbenzene (purity 55%) were used.
Perform suspension polymerization and perform classification operation to obtain an average particle size of 7.2 μm.
m, a styrene-based crosslinked polymer fine particle having a standard deviation of 1.3 μm.
Particles were obtained. When the adhesion of the obtained styrene-based crosslinked polymer fine particles was evaluated in the same manner as in Example 1, only a residual ratio of 4.8% was shown.

[0028]

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

Continuation of the front page (72) Inventor Akira Yoshimatsu 674-50 Hironishi, Wakayama (56) References JP-A-1-197721 (JP, A) JP-A-1-96626 (JP, A) JP-A-62-86331 (JP, A) JP-A-1-243028 (JP, A) JP-A-59-189324 (JP, A) JP-A-56-137123 (JP, U) JP-A-49-142253 (JP, U) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1339

Claims (2)

(57) [Claims] 1. A hydroxyl group or a carboxy group as a substituent in a molecule.
A hydroxyl group or a carboxyl group obtained by a polymerization reaction using a polymerizable monomer (A) having at least one functional group selected from a sil group and having no epoxy group as an essential component.
Having at least one type of functional group selected from a sil group ,
A spacer for a liquid crystal display, comprising crosslinked polymer fine particles having no epoxy group. 2. As an essential component, as a substituent in a molecule
The liquid crystal display spacer according to claim 1, wherein the polymerization is carried out using a polymerizable monomer (A) having at least one functional group selected from a hydroxyl group and a carboxyl group and having no epoxy group. Manufacturing method.