JP4580641B2 - Liquid crystal cell spacer and liquid crystal panel - Google Patents

Description

  The present invention relates to a liquid crystal cell spacer and a liquid crystal panel that can suppress abnormal alignment of liquid crystal around and between spacers and prevent light leakage that occurs during energization. Specifically, the present invention physically regulates the orientation of liquid crystal molecules at the interface between the liquid crystal and the spacer by forming micropores on the spacer surface by chemical etching and introducing long-chain alkyl groups. In addition, the present invention relates to a liquid crystal cell spacer and a liquid crystal panel that make it possible to achieve both the prevention of light leakage due to liquid crystal alignment anomaly and the prevention of liquid crystal cracking due to the excessive restriction of liquid crystal. In addition, the present invention relates to a liquid crystal cell spacer that is effective as a transparent spacer and a colored spacer, and a good liquid crystal panel with high contrast.

  In recent years, liquid crystal display devices are widely used for mobile applications, touch panel applications, and the like, and there is a strong demand for good display quality as image quality and screen size increase. However, in such an element of the liquid crystal display device, the alignment of the liquid crystal becomes irregular at the interface between the liquid crystal and the spacer, an abnormal alignment phenomenon occurs, and light deterioration resulting from the phenomenon causes a deterioration in quality. Reduce the contrast. The light leakage that occurs at the spacer interface disappears when liquid crystal molecules are aligned vertically to the spacer interface.

As a method of solving the problem caused by the abnormal alignment phenomenon by vertical alignment of liquid crystal molecules, a linear alkyl group is introduced to the spacer surface and the liquid crystal molecules are vertically aligned to the spacer surface to avoid the occurrence of abnormal alignment phenomenon. It has been proposed (see, for example, Patent Document 1).
JP-A-8-328018

  However, although the present inventor has a certain effect in preventing the abnormal alignment phenomenon of the liquid crystal at the interface between the spacer and the liquid crystal in the method as in Patent Document 1, the regulation range of the liquid crystal is too wide. As a new problem, it has been found that disclination, that is, a phenomenon that the liquid crystal between the spacers appears to be connected (hereinafter referred to as “liquid crystal cracking”) occurs, and the display quality is greatly deteriorated. It was. In particular, in a super twisted nematic liquid crystal (hereinafter referred to as “STN liquid crystal”) mode liquid crystal display element, such abnormal alignment of the liquid crystal is likely to occur. Moreover, when it modifies with a linear alkyl group like patent document 1, the entanglement phenomenon of alkyl will appear, and aggregation will generate | occur | produce in the dry spraying which does not use a dispersion medium, and the tendency to reduce display performance significantly is strong.

The object of the present invention is to solve the problems that could not be solved conventionally, and the object is to provide a liquid crystal cell spacer useful for preventing liquid crystal cracking of the liquid crystal panel. It is.
Another object of the present invention is to prevent liquid crystal cracks and advantageously suppress abnormal alignment of the liquid crystal at the interface between the liquid crystal and the spacer and between the spacers to prevent light leakage that occurs during non-energization and energization. It is.
Furthermore, the subject of this invention is preventing the aggregation which generate | occur | produces at the time of dry spraying, and improving adhesiveness with the prevention of a liquid crystal crack or the abnormal orientation of a liquid crystal.

  In order to solve the above-mentioned problems, the present inventor has made various types of fine particles as prototypes and studied in detail. As a result, liquid crystal molecules can be successfully regulated by the physical regulation force of the micropores formed by chemical etching of the fine particle surface and in addition to the orientation regulation force of the long-chain alkyl group. The headline and the present invention were completed.

That is, the present invention comprises a group of synthetic resin fine particles obtained by polymerization of monomers, and the surface of each synthetic resin fine particle is chemically etched with acid or alkali, a surfactant and an organic solvent as essential components. The present invention relates to a liquid crystal cell spacer characterized in that fine holes are formed by treatment and a long-chain alkyl group is introduced on the surface of the synthetic resin fine particles.

  According to the liquid crystal cell spacer of the present invention, the surface of the synthetic resin fine particles obtained by polymerization of the monomer is provided with micropores by chemical etching treatment, and long-chain alkyl groups are introduced. Due to the alignment restriction of the liquid crystal molecules due to the fine pores, when used in a liquid crystal panel, the restriction range is much narrower than the liquid crystal restriction range when only a long-chain alkyl group effective for alignment restriction is used, and liquid crystal cracks may occur. Furthermore, since the alignment regulating force of the long-chain alkyl group is adjusted by the micropores, it is possible to prevent liquid crystal cracking and effectively suppress abnormal alignment of the liquid crystal.

(1) Liquid crystal cell spacer Synthetic resin-based fine particles obtained by polymerization of monomers, the surface of which is provided with micropores by chemical etching treatment, and a long-chain alkyl group is introduced. .

  The fine holes are fine holes having a shape, a size, a depth, a number, and the like showing a liquid crystal regulation range that does not cause liquid crystal cracks. Preferably, the fine holes exhibit an appropriate liquid crystal regulation range, can physically prevent light leakage during non-energization and energization, and do not cause aggregation of spacers during dry spraying.

  The long chain alkyl group suppresses abnormal alignment of the liquid crystal by aligning the liquid crystal in a direction perpendicular to the surface of the fine particles. Since the long-chain alkyl group maintains the regulating ability due to the fine pores, a sufficient light leakage prevention effect can be obtained even with a small amount of introduction or with a relatively short-chain alkyl group.

  Preferably, the long chain alkyl group does not interfere with the fluidity of the fine particles. In general, when a surface treatment is performed with a long-chain alkyl group, the alkyl group is a long-chain molecule, so that the fine particles tend to be entangled with each other. However, when the alkyl group is introduced into the micropore, Since the contact of the fine particles with the alkyl group is suppressed and the range of entanglement due to the alkyl group is reduced, the fluidity between the fine particles is improved and the dry dispersibility is improved.

  Preferably, the long chain alkyl group enhances the adhesion of the synthetic resin-based fine particles to the substrate. The long-chain alkyl group present on the surface is entangled with, for example, molecules on the alignment film as the substrate, for example, polyimide molecules, and the adhesion to the substrate is increased.

(2) Synthetic resin fine particles Obtained by polymerization of monomers. Synthetic resin-based fine particles include composite fine particles such as inorganic-organic composite particles that can be chemically etched.

(3) Method for producing synthetic resin fine particles
The monomer polymerization method is not particularly limited, and an emulsion polymerization method, a suspension polymerization method, a seed polymerization method, and the like can be used. In particular, when the liquid crystal cell spacer of the present invention is produced, an emulsion polymerization method or a suspension polymerization method in an aqueous medium is preferable.

  Synthetic resin fine particles can be formed by aqueous suspension polymerization of a crosslinked polymer material. A polyfunctional monomer as a monomer can be used for such a crosslinked polymer material. Polyfunctional monomers include ethylene di (meth) acrylate, propylene di (meth) acrylates, butylene di (meth) acrylates, hexylene di (meth) acrylates, polyethylene glycol di (meth) acrylates, trimethylolpropane tri (meth) Acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol (meth) acrylate, allyl (meth) acrylate, metaallyl ( (Meth) acrylate, triallyl (meth) acrylate, triallyl (iso) cyanurate, triallyl trimellite, divinylbenzenes, di (meth) allyl phthalates, di (meth) acryloyl Examples include ruoxyethyl phthalates, vinylphenyl (meth) allyl ethers, di (meth) allylacrylamide, and the like.

  You may add the monofunctional monomer which can be copolymerized with the said polyfunctional monomer in the raw material of a bridge | crosslinking polymeric material. Examples of monofunctional monomers include methyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate, styrene, vinyltoluene, α-methylstyrene, (meth) acrylonitrile, malein dimethyl. Dimethyl fumarate, maleic acid, fumaric acid, (meth) acrylic acid, itaconic acid and the like.

  The molar ratio of the polyfunctional monomer to the monofunctional monomer in the above raw material is preferably 50 mol% or more when the total of the monomers is 100 mol%, More preferably, it is 100 mol%. Thus, when the ratio of the polyfunctional monomer is increased, a crosslinked polymer that hardly swells in an organic solvent can be obtained.

  As the radical polymerization initiator used for polymerization, a commonly used oil-soluble polymerization initiator can be used. For example, peroxide initiators such as benzoyl peroxide, o-chlorobenzoyl peroxide, o-methoxybenzoyl peroxide, 2,2-azobisisobutyronitrile, 2--2-azobis (2,4-dimethyl) An azo initiator such as valeronitrile can be used.

  In order to stably produce the spacer as a spherical body, aqueous suspension polymerization can be used. In the aqueous suspension polymerization, one or more suspension stabilizers can be used. Examples of the suspension stabilizer include polyvinyl alcohol, partially saponified polyvinyl alcohol, poly (meth) acrylate, or a copolymer thereof, polyacrylamide or a copolymer thereof, partially saponified polyacrylamide, carboxymethylcellulose, methylcellulose, Examples include water-soluble polymers such as ethyl cellulose, inorganic salt powders such as calcium phosphates and calcium carbonate.

  In order to stably produce the spacer as a granular material, aqueous emulsion polymerization can be used. In the aqueous emulsion polymerization, one or more emulsifiers can be used. Examples of the emulsifier include higher fatty acid salts such as sodium laurate and sodium oleate, alkyl sulfates such as sodium lauryl sulfate, and anionic surfactants such as alkylbenzene sulfonic acids such as dodecylbenzene sulfonate sodium. .

  In addition to the suspension polymerization method, a seed polymerization method can also be used. That is, the seed polymer particles dispersed in the aqueous dispersion medium can absorb a hydrophobic monomer and a polymerizable monomer other than these that can be polymerized in the presence of a polymerization initiator. Examples of hydrophobic monomers include styrene monomers such as styrene and divinylbenzene, (meth) acrylic acid esters such as glycidyl (meth) acrylate, ethylene glycol dimethacrylate, dimethylaminoethyl (meth) acrylate, and methylenebisacrylamide. And olefin monomers such as ethylene monomer, butadiene, vinyl chloride, and divinyloxybutane.

  The composite fine particle is not particularly limited. For example, an organic polymer skeleton and spherical fine particles having organic silicon in which a silicon atom is directly chemically bonded to at least one carbon atom in the organic polymer skeleton. Can be mentioned. These fine particles may be colored by including a dye and / or a pigment.

(4) Chemical etching treatment This treatment produces micropores on the surface of the synthetic resin fine particles. Various chemical etching methods are included.

For the chemical etching treatment, an acidic or alkaline etching solution can be used, and in particular, an etching solution containing acid or alkali, a surfactant and an organic solvent as essential components is used. When a surfactant or an organic solvent is not used, the treatment becomes uneven, and there is a possibility that the resulting fine particles are not sufficiently dispersed and the light leakage prevention effect is insufficient .

  As the etching solution, an acid solution containing at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, perchloric acid, and the like can be used as the acid. An alkaline solution containing at least one alkali selected from the group consisting of sodium, potassium hydroxide, lithium hydroxide, barium hydroxide, calcium hydroxide, ammonia and the like can be used.

  The acid or alkali concentration can be arbitrarily set. However, if the acid or alkali is too strong, the average particle diameter of the particles tends to be small, and the physical properties tend to be greatly reduced. Also, abnormal orientation occurs, and there is a tendency to cause light leakage and aggregation. The acid or alkali concentration is preferably 1 to 80% by weight, more preferably 5 to 70% by weight. The acid may have a high concentration, but the alkali has a lower concentration because particles dissolve when the concentration is high.

  As the surfactant, a nonionic surfactant can be used, and as the organic solvent, a water-miscible organic solvent that dissolves in water at an arbitrary ratio can be used. Using these components as essential components is particularly advantageous because the fine particles can be uniformly dispersed and stable treatment can be performed.

  Nonionic surfactants include Triton X-100, and various types can be used. Examples of water-miscible organic solvents include propanols such as methanol, ethanol, 2-propanol, and butanol. And lower alcohols such as acetone, dimethyl ketone, methyl ethyl ketone and methyl ketone, and ethers such as diethyl ether and dipropyl ether.

(5) Conditions for chemical etching treatment
Various conditions can be set. The treatment temperature is preferably 50 to 90 ° C, more preferably 60 to 80 ° C. When the processing temperature is low, it is difficult to form micropores. On the other hand, when the processing temperature is high, the mechanical strength of the spacer tends to decrease. From the relationship of the material, size, etc., of the synthetic resin fine particles, it may be controlled to have appropriate fine pores by changing the etching solution concentration, processing temperature, processing time, etc.

(6) Effect of chemical etching treatment Because of chemical etching in a wet rather than dry manner, fine pores are uniformly formed on the surface of the fine particles, unlike a physical etching phenomenon such as a low temperature plasma treatment. The micropores preferably regulate the liquid crystal molecules, so that the liquid crystal molecules are avoided from being aligned along the horizontal direction of the spacer surface and are aligned vertically. As a result, liquid crystal cracks can be prevented, light leakage of the liquid crystal between the spacer and the liquid crystal at the interface and between the spacers is effectively prevented, and a liquid crystal display with excellent contrast can be obtained.

  The microparticles having such micropores can both prevent liquid crystal cracking and prevent abnormal orientation. In addition, since the contact area between the particles is small, the fluidity between the particles is improved, and the dry dispersibility is good. Further, the fine particles may include a case where the synthetic resin-based fine particles subjected to the chemical etching treatment are colored particles, and the effect is maintained even when the colored particles are chemically etched. The display contrast can be increased.

(7) Introduction of long-chain alkyl group A long-chain alkyl group can be introduced by various methods. Long chain alkyl groups can be provided using a surface treating agent. In general, long-chain alkyl groups are introduced by treating the surface of raw material particles with a surface treatment agent.

A conventionally known method is adopted as a method for treating particles with a surface treatment agent, and is not particularly limited, and examples thereof include methods (i) to (iii) shown below.
(I) A method in which the raw material particles are immersed in a treatment liquid containing a surface treatment agent and then heated or reacted as it is, filtered and then dried.
(Ii) A method in which a surface treatment agent is added to a dispersion of raw material particles and then heated or reacted as it is, filtered and dried.
(Iii) A method in which a treatment liquid containing a surface treatment agent is sprayed onto the raw material particles, or the treatment liquid and the raw material particles are mixed and heated, or reacted as they are and dried.

  The solvent (dispersion medium) used in the treatment liquid or dispersion used in the above method is preferably one that does not react with the synthetic resin fine particles, and in particular, dioxane such as 1,4-dioxane, toluene, xylene and the like. It is better not to have a functional group, and it is preferable to carry out the reaction using an acid catalyst or an alkali catalyst in the presence of a nonpolar solvent.

  Preferably, the long chain alkyl group has 6 to 24 carbon atoms. Long-chain alkyl groups in this range can be suitably used for preventing liquid crystal cracking, preventing abnormal orientation, preventing light leakage, and improving fluidity and adhesion. When the number of carbon atoms is 6 or less, the effect of regulating the liquid crystal is hardly recognized. On the other hand, when the number of carbon atoms is 24 or more, it is generally difficult to obtain.

  Surface treatment agents for long-chain alkyl group introduction include caproic acid chloride, caprylic acid chloride, pelargonic acid chloride, capric acid chloride, lauric acid chloride, myristic acid chloride, palmitic acid chloride, stearic acid chloride, pehenic acid chloride, Acid chlorides such as lignoceric acid chloride, lauric acid anhydride, myristic acid anhydride, acid anhydrides such as palmitic acid anhydride, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl Acrylate, isobornyl acrylate, octyl acrylate, isooctyl acrylate, nonylphenoxyethyl acrylate, nonylphenol 10EO acrylate , Lauryl polyoxyethylene acrylate, octylphenol polyoxyethylene acrylate, stearylphenol polyoxyethylene acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, isobornyl methacrylate, octyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, cetyl methacrylate Polymerizable vinyl monoliths such as behenyl methacrylate, isodecyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, polyethylene glycol polytetraethylene glycol monomethacrylate, lauryl polyoxyethylene methacrylate, polyoxyethylene allyl glycidyl nonyl phenyl ether 2-ethylhe Sill isocyanate, isocyanate compound and octadecyl isocyanate, hexyl trimethoxy silane, silylated agent having an alkyl silyl group such as decyl trimethoxysilane.

  Although the usage-amount of a surface treating agent is not specifically limited, In order to fully process the surface of raw material particle, for example, a surface treating agent becomes like this. Preferably it is 0.1-100 weight% with respect to raw material particle, More preferably Is 0.5 to 70% by weight, more preferably 1 to 40% by weight. Within the above range, the surface of the raw material particles can be easily made hydrophobic. When the amount of the surface treatment agent is less than 0.1% by weight, the treatment efficiency may be lowered. When the amount of the surface treatment agent is more than 100% by weight, a large amount of unreacted surface treatment agent remains, and there is a possibility that the dry waving property is lowered.

  The temperature for surface treatment of the fine particles is preferably 50 to 250 ° C, more preferably 50 to 100 ° C. The time for the surface treatment is preferably 1 to 24 hours, and more preferably 2 to 10 hours. If the temperature or time is out of the above range, the surface may not be hydrophobicized. Further, drying under reduced pressure or under vacuum is preferable because surface treatment is promoted.

  The surface of the liquid crystal cell spacer obtained by surface-treating the raw material particles with a surface treatment agent containing a long-chain alkyl group as an active ingredient is considered to have a hydrophobic group that the long-chain alkyl group had, The hydrophobicity of the spacer surface increases, and light leakage around the spacer is difficult to increase even when vibration or impact is applied.

  In this way, after the treatment with the surface treatment agent, in order to remove the remaining surface treatment agent, after washing with a solvent such as water or alcohol, it is separated by filtration, centrifugation, etc., and crushed into single particles. Thus, a liquid crystal cell spacer is obtained.

  The average particle size of the fine particles used as the liquid crystal cell spacer can vary depending on the purpose, the function of the liquid crystal panel, etc., but is usually about 2 to 12 μm. In addition, when fine particles with a wide particle size distribution are incorporated in a liquid crystal display panel, it is difficult to keep the distance between the two transparent electrodes in the panel constant, and this may cause color unevenness during display. The standard deviation of the particle size distribution is preferably 20% or less, more preferably 10% or less of the particle size. Therefore, when the obtained crosslinked polymer fine particles have a wide particle size distribution, it is preferable to classify by the water tank classification method, the wet cyclone method, the dry method or the like.

(8) Liquid crystal panel The liquid crystal panel of the present invention can be obtained as a liquid crystal cell spacer in which the fine particles obtained as described above are interposed between electrode substrates. The liquid crystal cell spacer is composed of synthetic resin-based fine particles obtained by polymerization of a monomer, and the surface thereof is subjected to chemical etching treatment, provided with micropores, and a long-chain alkyl group is introduced. The liquid crystal cell spacer may have the above characteristics.

  Such a liquid crystal panel can solve various conventional problems and has high quality as a liquid crystal panel. Such a liquid crystal panel is capable of preventing liquid crystal cracking, preventing abnormal alignment of liquid crystal around the liquid crystal cell spacer, and preventing light from leaking around the spacer even when subjected to vibrations or shocks. Display quality can be maintained. The liquid crystal panel includes, for example, a pair of substrates, a liquid crystal interposed between the substrates, and a liquid crystal cell spacer that maintains a predetermined distance between the substrates.

Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited to these examples.
<Example 1>
(1) Chemical etching with acid on the surface of fine particles Into a separable flask, 24 parts by weight of a spacer [Hayakawa Rubber Co., Ltd., Haya beads L-11, particle size 5.75 μm], IPA (2-propanol) 16.6 Parts by weight, 16.6 parts by weight of deionized water, 0.1 part by weight of a nonionic surfactant [Wako Pure Chemical Industries, Ltd .: Triton X-100] 30% aqueous solution, and subjected to ultrasonic treatment, A dispersion is prepared.

  Next, while sufficiently stirring this dispersion, 150.5 parts by weight of 64% sulfuric acid water (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise, and then chemical etching with acid was performed at 80 ° C. for 10 hours. . After the etching is completed, the substrate is sufficiently washed with hot deionized water and then dried to obtain spacer particles. The average particle diameter of the spacer particles is 5.75 μm.

(2) Introduction of long-chain alkyl group (C = 6) 25 parts by weight of spacer particles obtained by the above chemical etching treatment are dispersed in 100 parts by weight of 1,4-dioxane. Next, while sufficiently stirring this dispersion, 10 parts by weight of caproic acid chloride [manufactured by Nippon Seika Co., Ltd.] was added dropwise, and then the particle surface was modified with an alkyl chain under the conditions of 60 ° C. for 10 hours. Thorough washing is performed and then dried to obtain spacer particles. The average particle diameter of the spacer particles is 5.75 μm.

<Example 2>
Introduction of long-chain alkyl group (C = 12) In Example 1, the same operation as in Example 1 was performed except that caproic acid chloride was replaced with lauric acid chloride [manufactured by Nippon Seika Co., Ltd.] to obtain spacer particles. . The average particle size of the spacer particles is 5.75 μm.
<Example 3>
Introduction of long-chain alkyl group (C = 18) In Example 1, the same procedure as in Example 1 is performed except that the acid chloride is changed to stearic acid chloride [manufactured by Nippon Seika Co., Ltd.] to obtain spacer particles. The average particle diameter of the spacer particles is 5.75 μm.
<Example 4>
Introduction of long-chain alkyl group (C = 24) In Example 1, the same procedure as in Example 1 is performed except that the acid chloride is replaced with lignoceric acid chloride [manufactured by Hayakawa Rubber Co., Ltd.] to obtain spacer particles. The average particle diameter of the spacer particles is 5.75 μm.

<Example 5>
(1) Chemical etching with alkali on the surface of fine particles Into a separable flask, 16 parts by weight of a spacer [Hayakawa Rubber Co., Ltd., Hayabies L-11, particle size 5.75 μm], 15.2 parts by weight of IPA, deionized water 15.2 parts by weight and 0.1 part by weight of a 30% aqueous solution of nonionic surfactant Triton X-100 are added and subjected to ultrasonic treatment to prepare a dispersion.

  Next, 246 parts by weight of a 0.1 mol / L sodium hydroxide solution [manufactured by Wako Pure Chemical Industries, Ltd.] was added dropwise with sufficient stirring of the dispersion, and then at 80 ° C. for 10 hours. Chemical etching with alkali is performed. After the etching is completed, the substrate is sufficiently washed with hot deionized water and then dried to obtain spacer particles. The average particle diameter of the spacer particles is 5.75 μm.

(2) Introduction of long-chain alkyl group (C = 24) In Example 4, the same operation as in Example 4 was carried out except that the spacer particles were replaced with spacers obtained by the above-mentioned chemical etching treatment. obtain. The average particle diameter of the spacer particles is 5.75 μm.

<Example 6>
(1) Chemical etching of colored particles In the etching process of Example 1, the spacer to be etched was manufactured by Hayakawa Rubber Co., Ltd., Hayabies L-11, particle size of 5.75 μm as described in JP 2000-319529 A. Except for the colored particles (particle size 5.9 μm) obtained by the production method, the same operation as the etching treatment of Example 1 is performed to obtain spacer particles. The average particle size is 5.9 μm.

(2) Introduction of long-chain alkyl group (C = 24) In Example 4, the same operation as in Example 4 was performed except that the spacer particles were replaced with the spacer particles obtained by the above chemical etching treatment to obtain spacer particles. . The average particle diameter of the spacer particles is 5.9 μm.

<Comparative Example 1>
A spacer not subjected to a chemical etching treatment (Hayakawa Rubber Co., Ltd., Haya beads L-11, particle size of 5.75 μm) is used as the liquid crystal spacer.
<Comparative Example 2>
Long-chain alkyl groups are introduced into colored fine particles that have not been chemically etched.
In a separable flask, 25 parts by weight of colored particles (particle size: 5.9 μm) obtained by the production method described in JP-A-2000-319529 is dispersed in 100 parts by weight of 1,4-dioxane. Next, 10 parts by weight of dodecanoyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise with sufficient stirring of the dispersion, and then the particle surface was modified with an alkyl chain at 60 ° C. for 10 hours, and acetone was added. Thorough cleaning with is performed and then dried to obtain spacer particles. The average particle diameter of the spacer particles is 5.9 μm.

A liquid crystal display element using the obtained fine particles as a liquid crystal cell spacer is evaluated. The results are shown in Table 1.
Evaluation method Each parameter is measured as follows.
<Particle size>
For measurement of the particle size and particle size distribution, a Coulter counter ZM / VC-256 (manufactured by Beckman Coulter, Inc.) is used, and about 30,000 particles are measured and averaged. When using, calibrate using the company's standard particles.
<Mechanical strength>
About mechanical strength, 10% compressive strength and compression recoverability are measured using a micro compression tester [MCTM-200 type, manufactured by Shimadzu Corporation]. The measurement method will be described below.
The 10% compressive strength is obtained by determining the particle diameter d for one sample particle spread on the sample stage with the attached microscope measuring instrument, and then breaking the sample particle toward the center of the particle at a compression rate of 0.675 g / sec. The load P at the initial 10% compression modulus of the particles is applied to the formula: G = 28P / πd ² and obtained. In this way, the 10% compressive strength G value (kgf / mm ² ) at 20 ° C. is calculated. This operation is performed for five different particles whose diameter is observed to be the average, and the average value is defined as the 10% compressive strength of the particles. In this case, the load speed is 0.27 g / sec.
The 100% recovery rate applies a load up to 1 grf in the direction of the center of the particle and then unloads the load to 0 grf. Data during this period is recorded in a displacement-load curve, and the ratio of the measured value of the recovery displacement (L ₂ ) when unloaded to 0 grf to the displacement (L ₁ ) from the origin to ₁ grf is expressed as a percentage. In this case, the loading speed is 0.27 g / second and the unloading speed is 0.029 g / second. If necessary, convert 1kgf ≈ 9.80665N.
<Evaluation of light dispersion between spraying property, adhesion, liquid crystal spacer interface and spacer>
A glass substrate having a transparent electrode and an alignment film is rubbed with absorbent cotton and subjected to an alignment treatment, and the obtained spacer particles are used as spacers for a liquid crystal display device. Spread up. The N ₂ gas flow rate is 3.0 kgf / cm ² , and the pipe is a minus pipe. At this time, the number of rotations of the feeder is adjusted so that the dispersion amount of the spacers on the glass substrate is 100 to 120 pieces / mm ² . The glass substrate thus obtained is observed with an optical microscope to evaluate the dispersibility.
Next, 0.4 MPa of air is sprayed from an angle of 90 ° to an arbitrary location on the glass substrate for 1 minute from a distance of 3 cm, and the remaining ratio of the spacer is confirmed with an optical microscope to evaluate the fixing property.
Next, after forming a peripheral sealing material around the other glass substrate, they are bonded together so that the rubbing direction is at an angle of 240 degrees. Thereafter, the treatment is performed at 160 ° C. for 3 hours to cure the sealing agent, thereby producing an empty cell. After injecting a predetermined amount of STN type liquid crystal into the empty cell thus obtained, the injection port is closed, and a deflection film is attached to the surface of the glass substrate to produce a normally black mode liquid crystal display panel.
In this liquid crystal display panel, the presence or absence of liquid crystal spacers that break when bonded, light leakage at the liquid crystal spacer interface that occurs when a voltage of 2.5 V is applied between the upper and lower transparent electrodes, disclination between the liquid crystal spacers (liquid crystal cracks) ) Is observed with a transmission microscope.

  As shown in Table 1, in Examples 1 to 6, the obtained liquid crystal display elements were not observed to have any abnormal alignment at the interface between the liquid crystal molecules and the liquid crystal spacers even when a voltage of 2.5 V was applied. It is confirmed that vertical alignment of liquid crystal molecules occurs at the interface. There are no disclination lines (liquid crystal cracks) between the liquid crystal spacers, and no aggregation of the liquid crystal spacers scattered on the glass substrate is observed. Further, the movement after air injection hardly occurs due to the entanglement phenomenon between the long chain molecule of the alkyl group modified on the surface of the spacer particle and the polyimide molecule of the alignment film.

  In Comparative Example 1, the obtained liquid crystal display element has an abnormal alignment of the liquid crystal molecules at the interface between the liquid crystal molecules and the liquid crystal spacer when a voltage of 2.5 V is applied, and many particles that cause light leakage are generated. However, no disclination line between the spacers is observed. Aggregation occurs in the liquid crystal spacers dispersed on the glass substrate. Moreover, the movement of the liquid crystal spacer after air injection is confirmed.

  In Comparative Example 2, the liquid crystal display element obtained was not observed to have an abnormal alignment at the interface between the liquid crystal molecules and the liquid crystal spacer even when a voltage of 2.5 V was applied, and the vertical alignment of the liquid crystal molecules at the interface between the liquid crystal molecules and the liquid crystal spacer was It is confirmed that it is super heavy. However, since the range that regulates the liquid crystal is too wide, it is observed that the alignment of the liquid crystal molecules around the liquid crystal spacer interface is disturbed and a large number of disclination lines are generated between the liquid crystal spacers. In addition, in the liquid crystal spacers spread on the glass substrate, many aggregations due to entanglement of alkyls occur.

  The liquid crystal cell spacer of the present invention can be produced by subjecting the surface of the synthetic resin fine particles to chemical etching and introducing a long chain alkyl group to the surface of the synthetic resin fine particles. The fine pores formed by chemical etching treatment can prevent liquid crystal cracking due to the alignment regulating force of the liquid crystal molecules. In addition to being able to produce a sufficient light leakage prevention effect even with a short alkyl group, it is possible to improve the fixing force and the dry dispersibility, which is useful as the shape of a spacer for a liquid crystal panel. The liquid crystal panel of the present invention can be manufactured using a liquid crystal cell spacer having such characteristics, and can prevent not only abnormal alignment of liquid crystal molecules but also liquid crystal cracks, has high contrast, and has display defects. Even if vibration or impact is applied, the display performance does not change and the display performance is high over a long period of time.

Claims (6)

It consists of a group of synthetic resin fine particles obtained by polymerization of monomers, and the surface of each synthetic resin fine particle is provided with fine pores by chemical etching treatment using acid or alkali, surfactant and organic solvent as essential components. A liquid crystal cell spacer, wherein a long chain alkyl group is introduced on the surface of the synthetic resin fine particles. The etching solution containing at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and perchloric acid is used for the chemical etching treatment. Liquid crystal cell spacer . Etching solution containing at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, calcium hydroxide and ammonia is used for the chemical etching treatment. The liquid crystal cell spacer according to claim 1 . The liquid crystal cell spacer according to claim 1, wherein the long-chain alkyl group contains 6 to 24 carbon atoms . The liquid crystal cell spacer according to claim 1, wherein the liquid crystal cell spacer is a colored particle . A liquid crystal panel comprising a pair of substrates, a liquid crystal interposed between the substrates, and a liquid crystal cell spacer that maintains a predetermined distance between the substrates,
The liquid crystal cell spacer is composed of a group of synthetic resin fine particles obtained by polymerization of monomers, and the surface of each synthetic resin fine particle is chemically etched with acid or alkali, surfactant and organic solvent as essential components. A liquid crystal panel, wherein fine holes are provided by treatment, and a long-chain alkyl group is introduced on the surface of the synthetic resin fine particles .