JPH03246521A - Production of spacer for liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain the spacers for liquid crystal display having the good adhesiveness to a panel surface by impregnating a hydrophilic monomer to fine particles of a crosslinked polymer and executing polymn. CONSTITUTION:The hydrophilic monomer is impregnated into the fine particles of the crosslinked polymer and the polymn. is executed. The average particle size of the fine particles of the crosslinked polymer varies with the kinds of liquid crystal display panels and is usually about 5 to 10 mum. If the particle size distribution is wide, the specified spacing between two sheets of transparent electrodes in the panel cannot be maintained in the case of incorporation of the spacers into the liquid crystal display panel and such is the cause for the generation of unequal colors at the time of display; therefore, the standard deviation is preferably <=20% of the particle sizes specified above. The hydrophilic monomers soluble in water or alcohol org. solvents are usable as the hydrophilic monomer. The spacers for liquid crystal display having excellent adhesiveness on the electrode panel surface are obtd. in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a novel spacer for a liquid crystal display, and in particular to a method for manufacturing a spacer for a liquid crystal display that has good adhesion to a panel surface. be.

[Problems to be solved by conventional techniques and inventions] Conventionally,
In liquid crystal display panels, particles of a predetermined diameter made of inorganic or organic substances are used as spacers in order to maintain the parallelism of the panel.

The required performance as a spacer for liquid crystal display panels is as follows:
l) Narrow particle size distribution, 2) Sufficient strength,
3) Good adhesion to the liquid crystal panel surface. Among these performances, various methods have been tried with respect to particle size distribution hardness and have reached a nearly satisfactory level, but no satisfactory performance has been obtained regarding adhesion to the liquid crystal panel surface. do not have. If the spacer moves between panels during panel fabrication, the panel gap will not be properly adjusted, and the polyimide alignment film on the electrode panel surface will be damaged, causing problems such as inhibiting liquid crystal alignment in that area.

[Means to solve the problem]

The present inventors have completed the present invention as a result of intensive studies aimed at solving the above-mentioned drawbacks of the prior art and obtaining a spacer for a liquid crystal display that has excellent adhesion to the electrode panel surface.

That is, the present invention provides a method for producing a spacer for a liquid crystal display, characterized in that crosslinked polymer fine particles are impregnated with a hydrophilic monomer and polymerized, and the crosslinked polymer fine particles are impregnated with a hydrophilic monomer, a crosslinked A method for producing a spacer for a liquid crystal display, characterized in that the spacer is impregnated with a hydrophilic monomer and a polymerization initiator and polymerized, and the crosslinked polymer fine particles are impregnated with a hydrophilic monomer, a hydrophilic polymer, and a crosslinkable monomer. A method for producing a spacer for a liquid crystal display, characterized in that the spacer is impregnated with a polymer and a polymerization initiator, and polymerized, and a monomer mixture containing a nonionic hydrophilic monomer and a crosslinkable monomer as essential components. The present invention provides a method for manufacturing a spacer for a liquid crystal display, characterized in that suspension polymerization is carried out using the present invention.

The crosslinked polymer fine particles used in the present invention include styrene crosslinked polymers such as styrene/divinylbenzene, styrene/ethylene glycol dimethacrylate, styrene/diethylene glycol dimethacrylate, styrene/butadiene, methyl (meth)acrylate/divinylbenzene, methyl (meth)acrylate/ethylene glycol dimethacrylate, methyl(meth)acrylate/diethylene glycol dimethacrylate, methyl(meth)acrylate/methylenebisacrylamide, etc.
meth)acrylic acid ester crosslinked copolymer; ethylene/
Fine polymer particles made of known copolymers such as olefin crosslinked copolymers such as butadiene, methyl vinyl ether/divinyloxybutane, vinyl acetate/divinyloxybutane, and vinyl chloride/divinylbenzene can be used.

In the above copolymer composition, the amount of the crosslinkable monomer in the total monomers can be appropriately selected depending on the desired physical properties of the polymer fine particles, but it is 5% by weight of the total monomers. In particular, it is preferably 5 to 70% by weight.

If the amount of the crosslinkable monomer is less than the above amount, the strength of the resulting polymer fine particles will not be sufficient, which will cause color unevenness when incorporated into a liquid crystal display panel.

The average particle diameter of these crosslinked polymer fine particles varies depending on the type of liquid crystal display panel, but is usually about 5 to 10 mm. Note that when crosslinked polymer fine particles with a wide particle size distribution are incorporated into a liquid crystal display panel, it is not possible to maintain a constant distance between the two transparent electrodes in the panel, which may cause color unevenness during display. Therefore, it is preferable that the standard deviation of the particle size distribution is 20% or less of the particle size.

These crosslinked polymer fine particles are produced by methods such as suspension polymerization and seed polymerization, and are subjected to treatments such as classification as necessary.

After impregnating the thus obtained crosslinked polymer fine particles with a hydrophilic monomer and, if necessary, a crosslinking monomer and a polymerization initiator, polymerization is carried out. Hydrophilic monomers soluble in organic solvents are used, such as hydroxyethyl (meth)acrylate, diethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, butanediol mono(meth)acrylate, and glycerol. Things (
Examples include (meth)acrylic acid ester monomers such as meth)acrylate and polyethylene glycol polypropylene glycol mono(meth)acrylate; and water-soluble vinyl monomers such as N-vinylpyrrolidone and N-vinyloxazolidone. In addition, examples of crosslinking monomers include polyfunctional monomers such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and divinyloxybutane. Examples include monomers, and it is preferable to use relatively hydrophilic monomers. These monomers can be used alone or in combination of two or more.

However, from the viewpoint of liquid crystal contamination, these monomers are preferably nonionic, for example, cationic,
When an anionic monomer is used, the liquid crystal is likely to be contaminated, and as a result, the transition temperature is likely to be lowered.

In addition, when crosslinked polymer fine particles made of a monomer containing a halogen element such as chloromethylstyrene, bromoethyl methacrylate, or chloromethyl vinyl ether are used, the hydrophilic monomers include 2-methyloxazoline, 2-
Using oxazoline compounds such as ethyloxazoline,
They may be subjected to ring-opening polymerization.

On the other hand, as the initiator used for the polymerization of the vinyl monomer, commonly used oil-soluble polymerization initiators can be used. For example, benzoyl peroxide, lauroyl peroxide, 0-
Peroxide initiators such as chlorobenzoyl peroxide and 0-methoxybenzoyl peroxide; azo initiators such as 2,2-azobisisobutyronitrile and 2,2-azobis(2,4-dimethylvaleronitrile); agent can be used.

In the present invention, the amount of the hydrophilic monomer used is approximately 0.1 to 50 parts by weight, more preferably 0.1 to 20 parts by weight, per 1 part by weight of the crosslinked polymer fine particles.

The crosslinkable monomer may not be used in some cases, but when it is used, it is used in an amount of 0.01 to 20 parts by weight, more preferably 0.01 to 10 parts by weight, per 1 part by weight of the crosslinked polymer fine particles.

Incidentally, the total amount of the hydrophilic monomer and the crosslinkable monomer is preferably 50 parts by weight or less based on 1 part by weight of the crosslinked polymer fine particles. If the amount is too large, agglomeration during polymerization and stickiness of the obtained polymer particles tend to occur, which is not preferable.

Further, the above-mentioned polymerization initiator is appropriately used in a range of 0.1 to 15% by weight based on the total monomers.

In the impregnation (adsorption or absorption) step, a solvent may be used that dissolves the monomer and polymerization initiator to be impregnated, but does not dissolve the crosslinked polymer fine particles.

Among these, solvents that swell crosslinked polymer fine particles are more preferred. For example, tetrachloroethane, dichloroethane,
Toluene, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (T
HF) is more preferably used, and the temperature range is from room temperature to 40°C.
Impregnation treatment is carried out at a temperature of about In addition, crosslinked polymer fine particles are dispersed in a solvent such as methanol or ethanol, and a hydrophilic monomer, a crosslinkable monomer, and an initiator are added, and
The impregnation treatment may be carried out at a temperature of about 100°C, after distilling off the solvent under reduced pressure.

Furthermore, in the impregnation step, a hydrophilic polymer soluble in the solvent, such as polyvinyl alcohol, polytetrahydrofuran, polyethylene oxide, polypropylene oxide, polyethyleneimine, polyvinylpyrrolidone,
Bo+J (N-acyl ethyleneimine) or the like may be added.

In addition, the polymerization operation after the impregnation treatment involves redispersing the polymer fine particles from which the impregnating solvent has been separated into a solvent in which the impregnated hydrophilic monomer, crosslinkable monomer, and hydrophilic polymer are insoluble. Just go. As the solvent, for example, water to which an inorganic salt is added, or an aliphatic hydrocarbon solvent such as hexane or cyclohexane is used. In the polymerization step, various surfactants or protective colloids may be used to improve the dispersion stability of the polymer particles.

The object of the present invention can also be achieved by crosslinked polymer fine particles obtained by suspension polymerization using a monomer mixture containing a nonionic hydrophilic monomer and a crosslinkable monomer as essential components. be done.

Examples of the nonionic hydrophilic monomers include hydroxyethyl (meth)acrylate, diethylene glycol 7-(meth)acrylate, polyethylene glycol mono (meth)acrylate, butanediol mono (meth)acrylate, and glycerol mono (meth)acrylate. , (meth)acrylic acid ester monomers such as polyethylene glycol polybrobylene glycol mono (meth)acrylate, water-soluble vinyl monomers such as N-vinylpyrrolidone, N-vinyloxazolidone, etc. Among them, polyethylene glycol mono(meth)acrylate , polyethylene glycol polypropylene glycol mono(meth)acrylate are preferred.

Examples of crosslinking monomers include divinylbenzene, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinyloxybutane, etc. Examples include polyfunctional monomers, and lipophilic or hydrophilic monomers can be used as appropriate.

In the present invention, monomers of the above two groups are essential components, but monomers other than the above, such as lipophilic monomers such as styrene and methyl (meth)acrylate, can be combined as necessary. .

Among the above monomers, the amount of crosslinking monomer used is preferably 5% by weight or more, particularly 5 to 70% by weight of the total monomers. If the amount of the crosslinkable monomer is less than the above, the resulting fine polymer particles will not have sufficient strength, and if it is too much, the adhesion will be insufficient, which is not preferable.

As a suspension polymerization method, in addition to normal suspension polymerization, a seed polymerization method in which a monomer mixture is absorbed into seed polymer particles and then polymerized is used.

The fine polymer particles after polymerization can be filtered to remove the aqueous layer, washed with water and/or a solvent, and then isolated as a powder by conventional means such as spray drying and vacuum drying.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. In addition, in the examples, parts indicate parts by weight.

Example 1 50 parts of styrene, 50 parts of divinylbenzene (purity 55%)
Suspension polymerization was carried out using
Crosslinked polymer fine particles having a 0-1 standard deviation of 1.8-1 were obtained.

5 parts of the obtained crosslinked polymer fine particles were dispersed in 20 parts of DMF, 0.18 parts of 2.2-azobisisobutyronitrile, 2 parts of ethylene glycol dimethacrylate, and polyethylene glycol monomethacrylate (manufactured by NOF ■, Bremmer). PE350, ethylene oxide polymerization degree 7-9
By adding 10 parts (mol) and stirring at 35° C. for 15 hours, the crosslinked polymer fine particles were impregnated with the initiator, the hydrophilic monomer, and the crosslinkable monomer. This dispersion was filtered, the resulting polymer was redispersed in 450 parts of cyclohexane, 0.45 parts of Rheodol 5P-SIO (manufactured by Kao ■, nonionic surfactant) was added, and the mixture was stirred at 62°C for 15 hours. The monomer was then polymerized. The obtained fine particles were washed with ion-exchanged water and alcohol, and then isolated and dried to obtain the intended spacer for liquid crystal display.

When the adhesion of the obtained spacer to the liquid crystal panel was evaluated by the method described below, it showed a residual rate of 85%.

Evaluation method: Weigh 0.5 g of a spacer for liquid crystal display that has been dried under reduced pressure (60°C/24 hours), and use Freon 53-E (manufactured by Daikin Industries, Ltd.) / Isopropanol (manufactured by Wako Pure Chemical Industries, Ltd.) =
3/2 (V/V) Disperse in 50 t ILl of mixed solvent.

A glass plate coated with a polyimide film (manufactured by Nichichi Kagaku ■, Sunever 150) was placed on a 1010x5 glass plate.
After coating with a thickness of 0 μm and sintering at 200° C. for 30 minutes), it was immersed for 10 seconds and left at room temperature for 5 minutes to evaporate the dispersion medium. After measuring the number of liquid crystal spacers within a predetermined field of view using an optical microscope, an air gun (1 kg/cm", diameter 1
III11, distance Ws911III) Air was blown onto the glass plate for 10 seconds, and the number of liquid crystal spacers within a predetermined field of view was remeasured. The residual rate was calculated from the change in the number of particles before and after spraying, and was used as an index of adhesion.

Examples 2 to 9 Comparative Examples 1 to 4 Suspension polymerization was carried out using various monomer compositions shown in Table 1, and a classification operation was performed to obtain crosslinked polymer fine particles.

These crosslinked polymer fine particles were treated in the same manner as in Example 1 using various hydrophilic monomers and crosslinkable monomers. Furthermore, the adhesion of each of the obtained liquid crystal display spacers was evaluated in the same manner as in Example 1.

The results are shown in Table 1.

For comparison, crosslinked polymer fine particles that were not treated with various hydrophilic monomers and crosslinkable monomers were also evaluated for adhesion, and the results are shown in Table 1.

As is clear from Table 1, the liquid crystal display spacers treated by the method of the present invention showed a residual rate of 72.3 to 92.0% and had good adhesion, but the liquid crystal display spacers without treatment It was found that the spacer used for this purpose showed almost no adhesion.

Example 10 Suspension polymerization was carried out using 50 parts of chloromethylstyrene and 50 parts of divinylbenzene (purity 55%), and a classification operation was performed to obtain a crosslinked polymer with an average particle size of 7.5-1 and a standard deviation of 1.4-1. Coalesced fine particles were obtained. 5 parts of the obtained crosslinked polymer fine particles were dispersed in 100 parts of dry benzonitrile, 10 parts of 2-methyloxazoline was added, and the mixture was reacted at 110°C for 15 hours. After washing the obtained fine particles with ion-exchanged water and a solvent,
It was isolated and dried to obtain a spacer for liquid crystal display.

The adhesion of the obtained spacer for liquid crystal display was evaluated in the same manner as in Example 1, and the residual rate was 82.3%.

Example 11 50 parts of styrene, 50 parts of divinylbenzene (purity 55%)
Suspension polymerization was carried out using
Crosslinked polymer fine particles having an oI of 1m and a standard deviation of 1.8 tm were obtained.

Five parts of the obtained crosslinked polymer fine particles were dispersed in 20 parts of DMF, and 0.18 parts of 2.2-azobisisobutyronitrile, 2 parts of ethylene glycol dimethacrylate, and polyethylene glycol monomethacrylate (manufactured by NOF ■, l/:/7-PE350) 10 parts, polyvinylpyrrolidone (manufactured by BASF, 9 companies, 40,000 parts) and 3
By stirring at 5° C. for 15 hours, the crosslinked polymer fine particles were impregnated with the initiator, the hydrophilic monomer, the crosslinkable monomer, and the hydrophilic polymer. This dispersion was filtered, and the obtained polymer was redispersed in 450 parts of cyclohexane. - Rheodol 5P-SIO (manufactured by Kao ■, nonionic surfactant)
0.45 part was added and the 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 spacer for a liquid crystal display.

When the adhesiveness of the obtained spacer for liquid crystal display was evaluated in the same manner as in Example 1, it showed a residual rate of 75.2%.

Example 12 40 parts of styrene, 40 parts of divinylbenzene (purity 55%)
1 part and 20 parts of polyethylene glycol monomethacrylate (manufactured by NOF ■, Premer PE350) were subjected to suspension polymerization, and a classification operation was performed to obtain a crosslinked polymer with an average particle size of 8.1-1 standard deviation of 1.4 tm. Fine particles were obtained.

The obtained crosslinked polymer fine particles were washed with ion-exchanged water and a solvent, and then isolated and dried to obtain a spacer for a liquid crystal display.

When the adhesiveness of the obtained spacer for liquid crystal display was evaluated in the same manner as in Example 1, it showed a residual rate of 78.9%.

Example 13 Styrene 50m, divinylbenzene (purity 55%) 45
1 part and 5 parts of polyethylene glycol monomethacrylate (manufactured by NOF ■, Blenmar PE350) were subjected to suspension polymerization, and a classification operation was performed to obtain crosslinked polymer fine particles having an average particle size of 9.14 and a standard deviation of 1.7. I got it.

5 parts of the obtained crosslinked polymer fine particles were dispersed in 20 parts of DNSo, and 0.18 parts of 2.2-azobisisobutyronitrile was dispersed in 20 parts of DNSo.
1 part, 2 parts of ethylene glycol dimethacrylate, polyethylene glycol monomethacrylate (manufactured by NOF ■,
By adding 10 parts of polyvinylpyrrolidone (manufactured by BASF, molecular weight 40,000) and stirring at 35°C for 15 hours, the initiator, hydrophilic monomer, and crosslinkable monomer were added to the crosslinked polymer fine particles. impregnated with a hydrophilic polymer and a hydrophilic polymer. This solution was filtered, the obtained polymer was redispersed in 450 parts of cyclohexane, and Rheodol 5P-S
0.45 part of IO (manufactured by Kao ■, nonionic surfactant) was added, and the 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 spacer for a liquid crystal display.

When the adhesiveness of the obtained spacer for liquid crystal display was evaluated in the same manner as in Example 1, it showed a residual rate of 90.2%.

Example 14 50 parts of styrene, 50 parts of divinylbenzene (purity 55%)
Suspension polymerization was carried out using
Crosslinked polymer fine particles with a standard deviation of 0.0711 m and a standard deviation of 1.8- were obtained.

5 parts of the obtained crosslinked polymer fine particles were dispersed in 50 parts of methanol, and 0.01 parts of 2,2-azobisisobutyronitrile was dispersed in 50 parts of methanol.
1 part, 0.8 part of N-vinylpyrrolidone, and 0.2 part of divinyloxybutane were added, and the solvent was distilled off under reduced pressure at 35°C. Next, the polymer particles were redispersed in 100 parts of cyclohexane, 0.1 part of Rheodol 5P-SIO (manufactured by Kao ■, nonionic surfactant) was added, and the monomer was polymerized at 62°C for 15 hours. Ta. The obtained fine particles were washed with ion-exchanged water and alcohol, and then isolated and dried to obtain a spacer for a liquid crystal display.

When the adhesiveness of the obtained spacer for liquid crystal display was evaluated in the same manner as in Example 1, it showed a residual rate of 95.4%.

〔Effect of the invention〕

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, damage to the polyimide alignment film can be prevented, making it suitable as a spacer for liquid crystal displays.

Claims (1)

[Claims] 1. A method for producing a spacer for a liquid crystal display, which comprises impregnating crosslinked polymer fine particles with a hydrophilic monomer and polymerizing the impregnated particles. 2. A method for producing a spacer for a liquid crystal display, which comprises impregnating crosslinked polymer fine particles with a hydrophilic monomer, a crosslinkable monomer, and a polymerization initiator, and polymerizing the impregnated particles. 3. A method for producing a spacer for a liquid crystal display, which comprises impregnating crosslinked polymer fine particles with a hydrophilic monomer, a hydrophilic polymer, a crosslinking monomer, and a polymerization initiator, and polymerizing the impregnated particles. 4. A method for producing a spacer for a liquid crystal display, which comprises carrying out suspension polymerization using a monomer mixture containing a nonionic hydrophilic monomer and a crosslinkable monomer as essential components.