JPH11326916A - Spacer for liquid crystal display element and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide spacers which does not exert an adverse influence on liquid crystals, such as disturbance of the alignment of the liquid crystals, and do not move in the liquid crystals. SOLUTION: The spacers for liquid crystal display elements are plastic microspherical bodies contg. at least >=5 wt.% monomer having >=2 ethylenically unsatd. groups and are formed by coating the surfaces of the plastic microspherical bodies obtd. by polymerizing at least >=1 kind of monomer having the ethylenically unsatd. groups with a monomer having 8-22C alkyl group and a monomer having an amino group or a monomer having an amide group and polymerizing the monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a spacer for a liquid crystal display device and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Generally, in a liquid crystal display device, a transparent electrode substrate on which an alignment layer is formed is opposed to a predetermined distance via a spacer for a liquid crystal display device, a liquid crystal is injected after a periphery is sealed, and an injection port is sealed. It is manufactured by stopping.

[0003] The spacer for a liquid crystal display element is used to keep the distance between the transparent electrode substrates constant, and glass fiber, polymer beads, and the like have been conventionally used. It was not easy to stably exist without giving any adverse effects such as disturbing and moving in the liquid crystal.

Japanese Patent Application Laid-Open No. 1-247154 discloses a method for producing fine particles in which organic or inorganic fine particles are coated with an olefin resin. However, in the fine particles obtained by this production method, the olefin-based resin is merely attached to the fine particles, and the olefin-based resin is separated from the fine particles with time, and moves in the liquid crystal, or contamination or the like. As a result, there is a problem that display unevenness or the like occurs in the liquid crystal display element and the display quality of the liquid crystal display element is degraded.

[0005] Japanese Patent Application Laid-Open No. 1-243027 discloses a method in which an acrylic resin is fixed to microspheres by a mechanical method (mechanofusion method) to obtain coated microspheres. However, even with these coated fine particles, the adhesion of the acrylic resin to the microspheres is insufficient, and the acrylic resin easily swells with the liquid crystal, and peels off.
Furthermore, there is a problem that the display quality of the liquid crystal display element is deteriorated by being eluted in the liquid crystal and contaminating the liquid crystal.

JP-A-5-216049 discloses crosslinked polymer fine particles having at least one of an amino group and an amide group on the surface. Although the crosslinked polymer fine particles do not cause a problem such as migration in the liquid crystal, there is a problem that the display quality of the liquid crystal display element is deteriorated due to the occurrence of abnormal alignment of the liquid crystal.

[0007]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a liquid crystal display having no adverse effects such as disturbing the alignment of liquid crystal.
It is another object of the present invention to provide a liquid crystal display element spacer that does not move in liquid crystal and a liquid crystal display element using the same.

[0008]

The spacer for a liquid crystal display device of the present invention is a plastic microsphere containing at least 5% by weight or more of a monomer having two or more ethylenically unsaturated groups. A monomer having an alkyl group having 8 to 22 carbon atoms, and a monomer having an amino group on the surface of the plastic microsphere obtained by polymerizing at least one or more monomers having a group Alternatively, it is characterized in that a monomer having an amide group is coated and polymerized.

Further, a liquid crystal display device according to the present invention is characterized by using the above-mentioned spacer for a liquid crystal display device. Hereinafter, the present invention will be described in detail.

The plastic microspheres constituting the spacer for a liquid crystal display element of the present invention are plastic microspheres containing at least 5% by weight or more of the monomer having two or more ethylenically unsaturated groups, It is obtained by polymerizing at least one or more monomers having an unsaturated group.

Examples of the monomer having two or more ethylenically unsaturated groups include, for example, a methylol alkyl having a plurality of methylol groups and a part or all of which forms an ester with (meth) acrylic acid. Examples include (meth) acrylate, polyoxyalkylene glycol di (meth) acrylate, triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, and diallyl acrylamide. These monomers may be used alone or in combination of two or more.

The plastic microspheres contain at least 5% by weight or more of the monomer having two or more ethylenically unsaturated groups. When the amount of the monomer having two or more ethylenically unsaturated groups is at least less than 5% by weight in the plastic fine sphere, the strength of the plastic fine sphere is reduced and the plastic fine sphere can function as a spacer for a liquid crystal display element. Disappears.

Examples of the methylolalkyl (meth) acrylate in which a part or all of the methylolalkyl having a plurality of methylol groups form an ester with (meth) acrylic acid include, for example, tetramethylolmethanetetra (meth) acrylate, Tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, tetramethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate Acrylate, glycerol di (meth) acrylate and the like can be mentioned.

The polyoxyalkylene glycol di (meth) acrylate includes, for example, polypropylene glycol tri (meth) acrylate and polypropylene glycol di (meth) acrylate.

The other monomer having an ethylenically unsaturated group is not particularly limited as long as it is a monomer having an ethylenically unsaturated group. For example, a styrene monomer such as styrene or α-methylstyrene may be used. And (meth) acrylates such as methyl (meth) acrylate.

Since the plastic microspheres contain at least 5% by weight of a monomer having two or more ethylenically unsaturated groups, at least one kind of the monomer having two or more ethylenically unsaturated groups is used. Although they are used, two or more of these may be used in combination, and one or more of the above-mentioned other monomers having an ethylenically unsaturated group may be used.

The plastic microspheres constituting the spacer of the liquid crystal display element of the present invention can be prepared by subjecting at least one kind of the monomer having an ethylenically unsaturated group to a known method, for example, a radical polymerization initiator. It can be obtained by performing suspension polymerization or the like in the presence. The obtained plastic microspheres preferably have an average particle size in the range of 0.1 to 100 μm, particularly preferably 1 to 100 μm. The plastic microspheres are colorless and transparent,
Alternatively, if necessary, it may be colored by a known method.

The spacer for a liquid crystal display element of the present invention has a monomer having an alkyl group having 8 to 22 carbon atoms and a monomer having an amino group or an amide group on the surface of the plastic fine sphere. It is obtained by coating and polymerizing a monomer.

The alkyl group having 8 to 22 carbon atoms is not particularly limited. For example, (meth) acrylic esters having a (meth) acryloyl group, organic silanes having a reactive functional group and the like are preferable.

The above (meth) acrylic esters having a (meth) acryloyl group include, for example, (meth) acrylic esters.
Examples thereof include 2-ethylhexyl acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate.

Examples of the reactive functional group of the organosilane having a reactive functional group include a silanol group, a trialkoxysilyl group, a dialkoxysilyl group, a monoalkoxysilyl group, and a trichlorosilyl group which can be converted into a silanol group. , A dichlorosilyl group, a monochlorosilyl group and the like. As the organic silanes, for example, octyltriethoxysilane, octylmethyldiethoxysilane, octyltrichlorosilane, octylmethyldichlorosilane, octyldimethylchlorosilane, isooctyltrichlorosilane, decyltriethoxysilane, decyltrichlorosilane, dodecyltrimethoxy Examples include silane, dodecyltrichlorosilane, octadecyltrimethoxysilane, octadecyltrichlorosilane, docosyltrichlorosilane, and the like.

The compound having an amino group is not particularly limited, but for example, an amino (meth) acrylate having a (meth) acryloyl group, an organic silane having a reactive functional group and the like are preferable.

The amino (meth) acrylates having a (meth) acryloyl group include, for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate and the like.

Examples of the reactive functional group of the organosilane having a reactive functional group include those having 8 to 22 carbon atoms.
And the same as in the case of the alkyl group. Examples of the organic silanes include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, and N-β (aminoethyl) γ-amino Propylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, bis (trimethoxysilylpropyl) amine, bis [3- (trimethoxysilyl) propyl] ethylenediamine and the like.

The compound having an amide group is not particularly limited. For example, (meth) acrylic amides having a (meth) acryloyl group, organic silanes having a reactive functional group and the like are preferable.

Examples of the (meth) acrylamides having a (meth) acryloyl group include acrylamide, N-isopropylacrylamide, N-isobutoxymethylacrylamide, N-hydroxymethylacrylamide, 2-acrylamide-2-methyl And propanesulfonic acid and 3-acrylamide-N, N-dimethylpropylamine.

Examples of the reactive functional group of the organosilane having a reactive functional group include those having 8 to 22 carbon atoms.
And the same as in the case of the alkyl group. Examples of the organic silanes include N- (3-triethoxysilylpropyl) -4-hydroxybutylamide, N-
(3-triethoxysilylpropyl) gluconamide and the like.

The monomer having an alkyl group having 8 to 22 carbon atoms, the monomer having an amino group or the monomer having an amide group may be used alone or in combination of two or more. May be.

The method of coating and polymerizing the surface of the plastic microspheres with a monomer having an alkyl group having 8 to 22 carbon atoms, a monomer having an amino group or a monomer having an amide group is as follows. Although not particularly limited, for example, the surface of the plastic fine sphere has the carbon number of 8
And a method of directly graft-polymerizing a monomer having an alkyl group of from 22 to 22. Further, when a hydroxyl group is present on the surface of the plastic microsphere, a monomer having an isocyanate group and an ethylenically unsaturated group is reacted to form a urethane bond, and after the surface has no hydroxyl group, Further, a monomer having an alkyl group having 8 to 22 carbon atoms and a monomer having an amino group or a monomer having an amide group may be reacted.

There is also a method of dispersing the plastic microspheres in a dispersion medium and then performing a surface treatment with the organic silanes. The dispersion medium is not particularly limited, but includes, for example, aromatic solvents such as toluene and xylene, aliphatic solvents such as hexane, heptane, octane, nonane, and decane; and alcohols such as ethanol and isopropyl alcohol. Or a mixed solvent of alcohols and water.

In the liquid crystal display device of the present invention, a spacer for a liquid crystal display device is scattered on a glass or film substrate on which a polyimide alignment film is arranged and rubbed, and the upper substrate is heated and pressed, and the liquid crystal is filled in the formed gap. Is obtained by filling.

Since the plastic microsphere contains at least 5% by weight or more of a monomer having two or more ethylenically unsaturated groups, the above-mentioned monomer having an alkyl group having 8 to 22 carbon atoms is coated and polymerized. The resulting coating layer firmly adheres to the plastic microspheres and does not peel off. Therefore, the spacer for a liquid crystal display element does not adversely affect the alignment of the liquid crystal and does not move in the liquid crystal.

In the above-mentioned spacer for a liquid crystal display element, the plastic microspheres may contain the monomer having an alkyl group having 8 to 22 carbon atoms and the monomer having an amino group or the monomer having an amide group. Since the coating is polymerized, the coating layer is rich in elasticity and adheres closely to the polyimide film of the liquid crystal display device. Therefore, the spacer for the liquid crystal display element does not have an adverse effect such as disturbing the alignment of the liquid crystal and does not move in the liquid crystal.

[0034]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 30 parts by weight of tetramethylol methane triacrylate
Suspension polymerization was carried out using 70 parts by weight of divinylbenzene and polyvinyl alcohol as a dispersant, and the average particle size was 6.0.
Polymer fine particles having a size of 2 μm and a standard deviation of 0.29 μm were obtained.
The obtained polymer microparticles were subjected to Charales Evans
Time-of-flight secondary ion mass spectrometer (TOF-SI)
As a result of surface analysis by MS), it was confirmed that a hydroxyl group derived from polyvinyl alcohol was present.

Next, 10 g of the obtained polymer fine particles were dispersed in 50 ml of toluene, and while stirring, di-n-dilaurate di-n-
0.1 g of butyltin was dissolved. To this solution, a solution of 5.0 g of methacryloyloxyethyl isocyanate dissolved in 30 ml of toluene was added dropwise with stirring, and further, 8
The reaction was performed for 5 hours in a water bath at 0 ° C. Thereafter, toluene was distilled off, and the polymer was washed and dried to obtain polymer fine particles having a polymerizable functional group in which a hydroxyl group on the surface reacted with an isocyanate group.

Next, 5 g of the obtained polymer fine particles were dispersed in 30 ml of toluene, and 3 g of stearyl acrylate was stirred under stirring.
And 1 g of N-isopropylacrylamide were dissolved, and then 0.2 g of benzoyl peroxide was further added. Then, this was heated to 75 ° C. under a nitrogen stream, stirred for 8 hours, reacted, and toluene was distilled off, washed, and washed at 140 ° C.
The spacer was obtained by drying in a dryer for 1 hour.

The obtained spacers were evaluated for the following spacer movement and abnormal liquid crystal alignment. The results are shown in Table 1 below.

Evaluation method (1) Evaluation of spacer movement The obtained spacer was sprayed at a rate of about 200 pieces / mm ² on a rubbed 15 cm × 15 cm glass substrate on which a polyimide alignment film was arranged. Rubbing direction (twist angle)
Is set to be 240 °, and the sealing around the glass substrate is heat-pressed using a sealing agent (Struct Bond XN-21-S manufactured by Mitsui Toatsu Chemicals, Inc.) to produce an empty cell. STN liquid crystal (ZL manufactured by Merck)
I-2293) was injected to obtain a liquid crystal cell. The approximate center of this liquid crystal cell was percussed with a Katsunuma percussion instrument 30 times, and the presence or absence of the spacer movement was observed with an optical microscope.

Further, another STN-type liquid crystal display element was manufactured in the same manner and annealed at 90 ° C. for 1 hour. After applying an AC voltage of 80 V for 10 seconds, the presence or absence of the spacer movement was observed with an optical microscope.

(2) Evaluation of liquid crystal alignment abnormality An STN type liquid crystal display element was manufactured by a known method, and 9
The alignment state of the liquid crystal after annealing at 0 ° C. for 1 hour was observed with an optical microscope.

Example 2 A spacer was obtained in the same manner as in Example 1 except that 2 g of decyl acrylate was used instead of 3 g of stearyl acrylate, and 1 g of dimethylaminoethyl methacrylate was used instead of 1 g of N-isopropylacrylamide. Was.

The spacer movement and abnormal liquid crystal alignment of the obtained spacer were evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Example 3 10 g of the polymer fine particles having an average particle size of 6.02 μm and a standard deviation of 0.29 μm obtained in Example 1 were mixed with hexane 100
The solution was immersed in a solution in which 0.2 g of dodecyltrimethoxysilane and 0.1 g of γ-aminopropyltrimethoxysilane were dissolved. This was heated to 60 ° C. and stirred for 1 hour, then hexane was distilled off, washed, and dried in a dryer at 140 ° C. for 1 hour to obtain a spacer.

The spacer movement and abnormal liquid crystal alignment of the obtained spacer were evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Example 4 0.2 g of octyltriethoxysilane was used instead of 0.2 g of dodecyltrimethoxysilane, and N- (3- was used instead of 0.1 g of γ-aminopropyltrimethoxysilane.
A spacer was obtained in the same manner as in Example 3, except that 0.2 g of (triethoxysilylpropyl) -4-hydroxybutyramide was used.

The movement of the obtained spacer and the abnormal liquid crystal alignment were evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

[0048]

[Table 1]

As is evident from the results shown in Table 1, the obtained spacer has no adverse effect such as disturbing the orientation of the liquid crystal and does not move in the liquid crystal.
It was confirmed that the spacer was suitable as a liquid crystal display element spacer.

Comparative Example 1 A spacer was obtained in the same manner as in Example 1 except that 2 g of methyl methacrylate was used instead of 3 g of stearyl acrylate.

The movement of the obtained spacer and the abnormal liquid crystal alignment were evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 2 A spacer was obtained in the same manner as in Example 3 except that 0.2 g of dodecyltrimethoxysilane was not used.

The movement of the obtained spacer and the abnormal liquid crystal alignment were evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

[0054]

[Table 2]

As is clear from the results shown in Table 2, it was confirmed that the obtained spacer exhibited abnormal liquid crystal alignment and was not suitable as a spacer for a liquid crystal display device.

[0056]

Since the spacer for a liquid crystal display element of the present invention has the above-described structure, it does not adversely affect the alignment of the liquid crystal and does not move in the liquid crystal. Therefore, the liquid crystal display element using the liquid crystal display element spacer of the present invention has high contrast and excellent display quality.

Claims (3)

[Claims] 1. A plastic microsphere containing at least 5% by weight or more of a monomer having two or more ethylenically unsaturated groups, wherein at least one or more monomers having an ethylenically unsaturated group are polymerized. The surface of the plastic microsphere obtained by the above is coated and polymerized with a monomer having an alkyl group having 8 to 22 carbon atoms and a monomer having an amino group or a monomer having an amide group. A spacer for a liquid crystal display device, characterized in that: 2. A method according to claim 1, wherein the monomer having two or more ethylenically unsaturated groups is a methylol alkyl (meth) having some or all of methylol alkyl having a plurality of methylol groups forming an ester with (meth) acrylic acid. ) Acrylate,
2. The composition according to claim 1, wherein the polyoxyalkylene glycol is at least one selected from the group consisting of poly (alkylene glycol) di (meth) acrylate, triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate and diallyl acrylamide. A spacer for a liquid crystal display element as described in the above. 3. A liquid crystal display device comprising the liquid crystal display device spacer according to claim 1.