JPH051106A - Production of hydrophilic crosslinkable polymer fine particle - Google Patents

Abstract

PURPOSE:To obtain the subject fine particles useful as a spacer for liquid crystal display having excellent adhesion to electrode panel face and capable of preventing damage of polyimide oriented film by linking a polyethylene glycol to the surface of crosslinkable polymer particles using a specific method. CONSTITUTION:(A) Crosslinkable polymer fine particles having a reactive functional group on at least the surface is reacted with (B) (modified) polyethylene glycol having a reactive group capable of reacting with the functional group of fine particles (A) by heating both components at 24-48hr under reflex to provide the objective fine particles. The fine particles (A) are e.g. obtained by subjecting a functional group-containing monomer such as glycidyl (meth) acrylate to suspension polymerization with a styrene-based monomer such as styrene or a (meth)acrylic acid ester-based monomer such as methyl (meth) acrylic and a crosslinkable monomer such as a divinyl benzene selected according to uses.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing hydrophilic crosslinked polymer fine particles, and more particularly to a method for producing hydrophilic crosslinked polymer fine particles suitable as a spacer for a liquid crystal display panel.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
In a liquid crystal display panel, in order to maintain the parallelism of the panel, inorganic or organic particles satisfying predetermined performance requirements are used as spacers for the liquid crystal display panel. The performance required as a spacer for a liquid crystal display panel includes 1) narrow particle size distribution, 2) sufficient strength, and 3) good adhesion to the liquid crystal panel surface. The particle size distribution and strength are basic performance requirements for a spacer for a liquid crystal display panel. Further, the reason why the adhesiveness to the liquid crystal display panel surface is required 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 and the liquid crystal alignment in that portion is hindered. It can be mentioned that.

Among these performances, various improvements have been attempted with regard to the particle size distribution and strength, and have reached almost a satisfactory level, but the performance of adhesion to the liquid crystal display panel surface is not satisfactory. Things have not been obtained. In addition, conventional organic liquid crystal display panel spacers are often composed of hydrophobic polymers in order to maintain strength,
For this reason, the spraying of the spacers on the panel surface has been mainly carried out using a flon-based organic solvent dispersion system. However, in consideration of the influence on the global environment which is increasing in recent years, the use of these CFC-based organic solvents is not preferable.

[0004]

Means for Solving the Problems As a result of intensive investigations by the present inventors, a spacer for an organic liquid crystal display panel, which solves the above-mentioned drawbacks of the prior art and has excellent adhesion to the electrode panel surface, has been obtained. The present invention has been completed by finding that the adhesion to a polyimide film is remarkably improved by chemically bonding polyethylene glycol to the surface of crosslinked polymer particles to make it hydrophilic, and further the dispersibility in water is remarkably improved. Came to do. That is, the present invention is characterized in that at least a crosslinked polymer fine particle having a reactive functional group on the surface and a modified or unmodified polyethylene glycol having a reactive group capable of causing a chemical reaction with these functional groups are reacted. The present invention provides a method for producing crosslinked polymer particles.

The reactive functional group of the crosslinked polymer fine particles in the invention includes at least one functional group selected from an epoxy group, a hydroxyl group and a carboxylic acid group. The crosslinked polymer fine particles having a functional group on at least the surface used in the present invention is a monomer having a functional group as described above [for example, epoxy group: glycidyl (meth) acrylate,
Hydroxyl group: hydroxyethyl (meth) acrylate, carboxylic acid group: (meth) acrylic acid], and styrene-based monomers such as styrene, p-methylstyrene, p-chlorostyrene and methyl (meth) acrylate, depending on the application. Suspension polymerization of (meth) acrylic acid ester-based monomers such as ethyl (meth) acrylate with crosslinkable monomers such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate, seeding It can be obtained by reacting by a method such as polymerization, but is not limited to these monomers, and it is possible to use a mixture of two or more kinds. As another method for producing crosslinked polymer fine particles having a functional group on at least the surface, an alkali of crosslinked copolymer fine particles containing a halohydrin derivative such as 3-chloro-2-hydroxypropyl (meth) acrylate as a constituent monomer Introduction of epoxy group by treatment, pt-
Introduction of hydroxyl groups by hydrolysis of cross-linked copolymer fine particles having butoxystyrene as a constituent monomer, and (meth) acrylic acid ester having methyl (meth) acrylate, ethylene glycol di (meth) acrylate as a constituent monomer A method of chemically treating the crosslinked copolymer fine particles to introduce a functional group, such as introduction of a carboxylic acid group by hydrolysis of the system crosslinked copolymer fine particles, can also be used.

The above-mentioned monomers to be the constituent units of the cross-linked copolymer can be used alone or in admixture of two or more. The weight ratio of the monomer having a functional group such as an epoxy group, a hydroxyl group and a carboxylic acid group to the monomer having no functional group and the crosslinkable monomer is 1/99 to 50/50. It is preferable. When the proportion of the monomer having a functional group is less than 1% by weight, the amount of the functional group becomes small and the effect of the present invention due to the bonding with the modified or unmodified polyethylene glycol becomes small. If it exceeds%, the proportion of the crosslinkable monomer in the crosslinked polymer fine particles inevitably decreases, resulting in insufficient particle strength, and when incorporated in a liquid crystal display panel, color unevenness during display is observed. It is not preferable because it causes the occurrence. 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 5 to 10 μm. When cross-linkable polymer fine particles having a wide particle size distribution are incorporated into a liquid crystal display panel, the distance between the two transparent electrodes in the panel cannot be kept constant, which causes color unevenness during display. Therefore, the standard deviation of the particle size distribution is preferably 20% or less of the particle size.

Modified or unmodified polyethylene glycol (hereinafter abbreviated as PEG) that can be used in the present invention
Has a reactive group capable of causing a chemical reaction with the functional group of the crosslinked polymer fine particles, and as such a reactive group,
Examples thereof include those selected from an epoxy group, a hydroxyl group, a carboxylic acid group, a carboxylic acid chloride residue, an amino group and an isocyanate group. Among such modified or unmodified PEG,
The modified or unmodified PEG having the above reactive groups at both ends is industrially produced, and epoxy modified: epoxy PE
G # 400, # 100 [SR-8EG, SR-2EG, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.], carboxylic acid modified: PEO # 400 acid, PEO
# 1000 acid, PEO # 4000 acid [Kawaken Fine Chemicals Co., Ltd.], amino modified: PEO # 400 amine, PEO
# 6000 amine (produced by Kawaken Fine Chemicals Co., Ltd.) and the like can be used. Both ends isocyanate modified P
EG can be easily synthesized by treating commercially available PEG with, for example, TDI (tolylene diisocyanate) or MDI (4,4′-diphenylmethane diisocyanate). Further, the modified PEG having the reactive group at one end is a method of introducing a carboxylic acid group by reacting commercially available monomethoxypolyethylene glycol (manufactured by Aldrich) with succinic anhydride, and reacting with ammonia gas after halogenation treatment. It can be easily obtained by modifying PEG having a hydroxyl group at one end by a known method such as a method of introducing an amino group. Further, the carboxylic acid group can be converted to a carboxylic acid chloride by treating with thionyl chloride.

The modified or unmodified PEG that can be used in the present invention preferably has a molecular weight of 2 mol or more and 250 mol or less in terms of the number of moles of ethylene oxide added, and is hydrophilic when the number of moles of addition is less than 2 mol. Is insufficient, the effect of the present invention is less manifested, and when it exceeds 250 mol, the reactivity is lowered. Further, it may be a copolymer with propylene oxide. In the present invention, it is necessary to appropriately select the reactive groups of the one-end and / or both-end modified or unmodified PEG depending on the functional groups present on the surface of the crosslinked polymer fine particles. For example, when the functional group present on the surface of the crosslinked polymer particles used is 1) an epoxy group: PE
The reactive group of G is a hydroxyl group, a carboxylic acid group or an amino group, and 2) the hydroxyl group: the reactive group of PEG is an epoxy group, a carboxylic acid group, a carboxylic acid chloride residue or an isocyanate group, 3 ) Carboxylic acid group: The reactive group of PEG is preferably an epoxy group, a hydroxyl group, or an amino group because surface treatment can be performed under mild conditions.

In the present invention, the reaction ratio between the crosslinked polymer fine particles and the modified or unmodified PEG varies depending on the combination of the reactive functional group of the crosslinked polymer fine particles and the modifying group of PEG and the introduction amount of these functional groups. Basically, about 10 times the amount of the above modified or unmodified PEG by weight of the crosslinked polymer particles.
The hydrophilic crosslinked polymer fine particles can be obtained by heating and reacting with the above in an inert solvent such as dioxane or toluene under reflux condition for about 24 to 48 hours. The hydrophilic cross-linked polymer fine particles obtained here are diluted and dispersed in a solvent such as methanol, filtered, washed with water and / or washed with a solvent, and then sprayed, dried under reduced pressure and the like to obtain a powder by a simple method. Can be separated.

[0010]

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. Reference Example 1 (Synthesis of Cross-Linked Polymer Fine Particles Containing Hydroxyl Group) Glycerol monomethacrylate (manufactured by NOF CORPORATION)
Suspension polymerization was carried out using 20 parts of Bremmer GLM), 10 parts of ethylene glycol dimethacrylate (manufactured by Tokyo Kasei Co., Ltd.), and 70 parts of divinylbenzene (purity 55%), and classification operation was performed to obtain an average particle size of 10 μm and standard deviation. To obtain 1.8 μm of crosslinked polymer fine particles. The obtained fine particles were washed with ion-exchanged water and a solvent and then isolated and dried to obtain crosslinked polymer fine particles.

Reference Example 2 (Synthesis of Epoxy Group-Containing Crosslinked Polymer Fine Particles) 40 parts of glycidyl methacrylate (manufactured by Tokyo Kasei)
Suspension polymerization was carried out using 60 parts of divinylbenzene (purity 55%), and classification was performed to obtain an average particle size of 7.8 μm with a standard deviation of
Crosslinked polymer particles having a size of 1.5 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.

Reference Example 3 (Synthesis of Crosslinked Polymer Fine Particles Containing Carboxylic Acid Group) 10 parts of methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 10 parts of ethylene glycol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), divinylbenzene (purity (55%) 80 parts were used for suspension polymerization and classification was performed to obtain an average particle size of 6.9 μm and a standard deviation of 1.3.
Crosslinked polymer particles having a size of 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.

[0013]Example 1 10 parts of the crosslinked polymer fine particles obtained in Reference Example 2 was added to dioxane.
Disperse into 50 parts, PEG # 2000 (Aldrich, MW
2000) 50 parts was added and the mixture was reacted under reflux for 96 hours. Obtained
Fine particles are dispersed / washed in methanol and then ion exchanged
After washing with water and solvent, isolate and dry to remove hydrophilic crosslinked polymer particles.
The particles were obtained. Hydrophilic cross-linked polymer thus obtained
Fine particles are used as spacers for liquid crystal display, and the liquid crystal panel
The adhesiveness to the adhesive was evaluated by the following method. That is, decrease in advance
0.5 g of pressure-dried (60 ℃ / 24hr) liquid crystal display spacer
Weighed, and Freon S3-E (manufactured by Daikin Industries, Ltd.) / ISOP
Lopanol (Wako Pure Chemical Industries, Ltd.) = 3/2 (V / V) mixed
Disperse in 50 ml of combined solvent. Into it Polyimide film-glass
(Nissan Kagaku Co., Ltd., Sun Ever 150 10cm x 5cm glass
Coated with a thickness of 100 μm and sintered at 200 ° C for 30 minutes)
It was immersed for 2 seconds, and the dispersion medium was evaporated at room temperature for 5 minutes. Optical microscope
The number of liquid crystal spacers within a given field of view was measured with a microscope.
After, air gun (1kg / cm², Caliber 1mm, distance 9mm)
Spray the air on the glass plate for 10 seconds, and
The number of sensors was measured again. Change in number before and after spraying
Then, the residual rate was calculated and the adhesiveness was evaluated. As a result,
The liquid crystal display spacer had a residual rate of 78.5%.

[0014]Example 2 10 parts of the crosslinked polymer fine particles obtained in Reference Example 2 was added to dioxane.
Dispersed in 50 parts, PEG # 4000 carboxylic acid at both ends (Kawaken
Fine Chemical Co., Ltd., PEO # 4000 carboxylic acid)
50 parts was added and the reaction was carried out under reflux for 48 hours. Fine particles obtained
Dispersed / washed in methanol and further deionized water and
After washing with a solvent, isolate and dry to obtain hydrophilic crosslinked polymer particles.
Obtained. Hydrophilic cross-linked polymer fine particles thus obtained
Using as a spacer for liquid crystal display,
The adhesiveness was evaluated by the
Pacer showed a survival rate of 82.9%.

[0015]Example 3 10 parts of the crosslinked polymer fine particles obtained in Reference Example 2 was added to dioxane.
Dispersed in 50 parts, PEG # 6000 amine at both ends (Kawaken fa
Added 50 parts of PEO # 6000 amine manufactured by In-Chemical Co., Ltd.
Therefore, the reaction was carried out under reflux for 48 hours. The obtained fine particles are
Disperse / wash in nol and then wash with ion-exchanged water and solvent
After purification, isolation and drying were performed to obtain hydrophilic crosslinked polymer fine particles. This
The hydrophilic crosslinked polymer fine particles obtained as
Used as an indicating spacer and attached in the same manner as in Example 1.
When the adhesion was evaluated, this liquid crystal display spacer
The residual rate was 81.6%.

[0016]Example 4 10 parts of the crosslinked polymer fine particles obtained in Reference Example 1 was added to dioxane.
Dispersed in 50 parts, epoxy modified PEG # 400 (SR-8EG,
Add 50 parts of Sakamoto Yakuhin Kogyo Co., Ltd. and reflux for 48 hours
I responded. Disperse / wash the obtained fine particles in methanol
After washing with ion-exchanged water and solvent, isolation and drying
Aqueous crosslinked polymer particles were obtained. Thus obtained
Use of hydrophilic crosslinked polymer particles as spacers for liquid crystal displays
And the adhesion was evaluated in the same manner as in Example 1.
By the way, this LCD spacer shows a survival rate of 85.4%.
It was

[0017]Example 5 10 parts of the crosslinked polymer fine particles obtained in Reference Example 1 was added to dioxane.
Dispersed in 50 parts, PEG # 4000 carboxylic acid at both ends (Kawaken
Fine Chemical Co., Ltd., PEO # 4000 carboxylic acid)
50 parts was added and the reaction was carried out under reflux for 48 hours. Fine particles obtained
Dispersed / washed in methanol and further deionized water and
After washing with a solvent, isolate and dry to obtain hydrophilic crosslinked polymer particles.
Obtained. Hydrophilic cross-linked polymer fine particles thus obtained
Using as a spacer for liquid crystal display,
The adhesiveness was evaluated by the
Pacer had a survival rate of 82%.

[0018]Example 6 Methoxy PEG # 5000 (manufactured by Aldrich) 250 parts, none
Mix 4.5 parts of water succinic acid and react at 120 ° C for 48 hours.
It was The acid value of the obtained carboxy-modified PEG is 11.7 KOHmg
/ G, hydroxyl value is 2.2KOHmg / g, which is almost quantitative
I was responding. 10 parts of crosslinked polymer fine particles obtained in Reference Example 1
Was dispersed in 50 parts of dioxane, and the carbohydrate obtained by the above method was
Add 50 parts of xy-modified PEG and react under reflux for 48 hours
It was Disperse / wash the obtained fine particles in methanol and
After washing with ion-exchanged water and solvent, isolate and dry to make it hydrophilic.
Bridge polymer particles were obtained. Hydrophilicity thus obtained
Using crosslinked polymer particles as spacers for liquid crystal displays,
When the adhesion was evaluated by the same method as in Example 1,
This liquid crystal display spacer showed a residual rate of 79%.

[0019]Example 7 PEG # 1000 (manufactured by Aldrich) 300 parts, TDI 10
4.4 parts were mixed and reacted at 60 ° C. for 8 hours. Got
Isocyanate-modified PEG has an isocyanate (%) of 5.
69%, hydroxyl value is 1.2KOHmg / g and reacts almost quantitatively
Was. 10 parts of the crosslinked polymer fine particles obtained in Reference Example 1
Dispersed in 50 parts of dioxane, isocyanate obtained by the above method
Add 50 parts of nate-modified PEG and react at 50 ° C for 48 hours
It was Disperse / wash the obtained fine particles in methanol and
After washing with ion-exchanged water and solvent, isolate and dry to make it hydrophilic.
Bridge polymer particles were obtained. Hydrophilicity thus obtained
Using crosslinked polymer particles as spacers for liquid crystal displays,
When the adhesion was evaluated by the same method as in Example 1,
This liquid crystal display spacer showed a residual rate of 82.6%.

[0020]Example 8 10 parts of the crosslinked polymer fine particles obtained in Reference Example 3 were mixed with 50 parts of toluene.
Part, and epoxy modified PEG # 400 (SR-8EG, Saka
Add 50 parts of Hakuyaku Kogyo Co., Ltd. and react under reflux for 48 hours
Let Disperse / wash the obtained fine particles in methanol.
After washing with deionized water and solvent, isolate and dry to make it hydrophilic.
Fine crosslinked polymer particles were obtained. Parents obtained in this way
Aqueous cross-linked polymer fine particles are used as spacers for liquid crystal display
And the adhesion was evaluated in the same manner as in Example 1.
By the way, this LCD spacer shows 90.1% survival rate.
It was

[0021]Example 9 10 parts of the crosslinked polymer fine particles obtained in Reference Example 3 were mixed with 50 parts of toluene.
50 parts of PEG # 1000 (manufactured by Aldrich)
Was added and the mixture was reacted under reflux for 48 hours. The obtained fine particles
Dispersed / washed in methanol and deionized water and solvent
After washing with, isolated and dried to obtain hydrophilic crosslinked polymer particles.
It was The hydrophilic crosslinked polymer fine particles thus obtained are
The same method as in Example 1 using as a spacer for liquid crystal display
When the adhesiveness was evaluated by
The rate of survival was 75.2%.

[0022]Example 10 10 parts of the crosslinked polymer fine particles obtained in Reference Example 3 were mixed with 50 parts of toluene.
And PEG # 6000 both ends amine (Kawaken Phi
Chemicals Co., Ltd., PEO # 6000 amine) 50 parts added
And reacted under reflux for 48 hours. The obtained fine particles are
Dispersed / washed in water and washed with ion-exchanged water and solvent
Then, it was isolated and dried to obtain hydrophilic crosslinked polymer fine particles. this
Liquid crystal display of the hydrophilic cross-linked polymer fine particles thus obtained
Used as a spacer for use and attached in the same manner as in Example 1.
The spacer for liquid crystal display showed 9
The residual rate was 1.6%.

[0023]Comparative Example 1 Obtained in Reference Example 1 without surface treatment by the method of the present invention
When the adhesiveness of the obtained crosslinked polymer fine particles was evaluated,
It only showed a residual rate of 4.8%.

[0024]

As is clear from the results of the above examples, the fine particles of the hydrophilic crosslinked polymer obtained in the present invention have 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 liquid crystal display.

Claims (3)

[Claims] 1. Hydrophilic cross-linking, characterized in that at least a cross-linked polymer fine particle having a reactive functional group on its surface is reacted with a modified or unmodified polyethylene glycol having a reactive group capable of chemically reacting with these functional groups. Method for producing polymer fine particles. 2. The method for producing hydrophilic crosslinked polymer particles according to claim 1, wherein the reactive functional group of the crosslinked polymer particles is at least one kind of functional group selected from an epoxy group, a hydroxyl group and a carboxylic acid group. 3. The modified or unmodified polyethylene glycol reactive group is selected from an epoxy group, a hydroxyl group, a carboxylic acid group, a carboxylic acid chloride residue, an amino group and an isocyanate group. The method for producing fine particles of the hydrophilic cross-linked polymer according to.