JP2006243719A - Manufacturing method for liquid crystal display device, spacer particle dispersion liquid, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a liquid crystal display device with which spacer particles can be arranged at positions corresponding to a non-pixel region on a substrate by using an ink jet device to suppress contamination of liquid crystal and an alignment film, and a spacer particle dispersion liquid, and the liquid crystal display device. <P>SOLUTION: The manufacturing method for the liquid crystal display device 1 which has a pixel region and the non-pixel region includes the stages of: discharging the spacer particle dispersion liquid having spacer particles 14 dispersed in a medium on the surface of a 1st substrate 2 or 2nd substrate 3 by using the ink jet device and arranging the spacer particles at designated positions corresponding to the non-pixel region; and placing the 1st substrate and 2nd substrate oppositely to each other one over the other across the liquid crystal and spacer particles. In the stage of overlapping the substrates oppositely to each other across the liquid crystal and spacer particles, the liquid crystal varies in volume resistance value by ≥1% before and after the liquid crystal is arranged, and change in nematic isotropic phase shift temperature of the liquid crystal is ≤±1°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for manufacturing a liquid crystal display device including a step of disposing spacer particles on a substrate using an inkjet device, and in particular, a method for manufacturing a liquid crystal display device with an improved spacer particle dispersion, and a spacer particle dispersion. And a liquid crystal display device.

Currently, liquid crystal display devices are widely used in personal computers, portable electronic devices, and the like. As shown in FIG. 9, a general liquid crystal display device has a structure in which two transparent substrates 201 and 202 are stacked so as to face each other.

On the inner surface of the transparent substrate 201, a color filter 203 and a black matrix 204 that defines the color filter 203 are formed. An overcoat layer 205 is formed on the color filter 203 and the black matrix 204. A transparent electrode 206 is formed on the overcoat layer 205. Further, an alignment film 207 is formed so as to cover the transparent electrode 206. On the other hand, a transparent electrode 208 is formed on the inner surface of the transparent substrate 202 at a position facing the color filter 203. Further, an alignment film 209 is formed so as to cover the inner surface of the transparent substrate 202 and the transparent electrode 208. On the other hand, polarizing plates 210 and 211 are disposed on the outer surfaces of the transparent substrates 201 and 202, respectively. The transparent electrodes 206 and 208 include a pixel electrode disposed in the pixel region and an electrode disposed outside the pixel region.

The transparent substrate 201 and the transparent substrate 202 are bonded via a sealant 212 in the vicinity of the outer peripheral edge of each. Spacer particles 213 are arranged in the gap between the alignment film 207 and the alignment film 209, and liquid crystal 214 is sealed. In this liquid crystal display device, the spacer particles 213 function to regulate the distance between the two transparent substrates 201 and 202 to maintain an appropriate liquid crystal layer thickness (cell gap).

As a method of arranging the spacer particles 213 when obtaining the liquid crystal display device 200, conventionally, the spacer particles 213 are dispersed using a wet spraying method using a solvent such as isopropanol, or using the pressure of air without using a solvent. A dry spraying method for spraying was used.
In this manufacturing method, since the spacers are uniformly and randomly distributed on the substrate of the transparent substrate 201, as shown in FIG. 9, on the pixel electrode, that is, on the display unit (pixel region) of the liquid crystal display device 200. Also, the spacer particles 213 were easily arranged. The spacer particles are generally made of synthetic resin, glass, or the like, and when the spacer particles are arranged on the pixel electrode, the spacer particle portion leaks light due to a biasing action. Further, when the alignment of the liquid crystal on the surface of the spacer particles is disturbed, light leakage occurs, the contrast and color tone are lowered, and the display quality is deteriorated. On the other hand, in a TFT liquid crystal display device, TFT elements are arranged on a substrate. When spacer particles are disposed on the TFT element, the element may be damaged when pressure is applied to the substrate.

In order to solve the problems associated with random dispersion of the spacers, various attempts have been made to dispose the spacers under the light shielding layer (non-pixel region).

As a method of arranging the spacers only at specific positions, for example, Patent Document 1 discloses a method of dispersing the spacers through the mask after matching the position where the mask having the opening is desired to be arranged. On the other hand, Patent Document 2 discloses a method in which a spacer is electrostatically attracted to a photoconductor and then transferred to a transparent substrate. Patent Document 3 discloses a method for manufacturing a liquid crystal display device in which a spacer is arranged at a specific position by electrostatic repulsion by applying a voltage to pixel electrodes on a substrate and dispersing charged spacers. Has been.

However, in the method described in Patent Document 1 or Patent Document 2, since the mask and the photoconductor are in direct contact with the substrate, the alignment film on the substrate tends to be damaged. Therefore, the image quality of the liquid crystal display tends to deteriorate. On the other hand, in the method described in Patent Document 3, an electrode according to the pattern to be arranged is required, and therefore it is impossible to arrange the spacer at an arbitrary position.

On the other hand, Patent Document 4 discloses a method of arranging spacers using an ink jet apparatus. In this method, the mask and the photoconductor do not come into direct contact with the substrate itself, and the spacer can be arranged in an arbitrary pattern at an arbitrary position.
Japanese Patent Laid-Open No. 4-198919 JP-A-6-258647 JP-A-10-339878 JP-A-57-58124

As described above, in the methods described in Patent Documents 1 to 3, the alignment film on the substrate may be damaged, or the spacer may not be disposed at an arbitrary position.

On the other hand, in the spacer particle dispersion method described in Patent Document 4, droplets of a spacer particle dispersion liquid in which spacer particles are dispersed are discharged onto a substrate. In order to obtain a liquid crystal display device having excellent display quality without light leakage due to the spacer particles, it is necessary to discharge the spacer particle dispersion liquid toward the light shielding region of the substrate and to dispose the spacer particles under the light shielding region. Furthermore, in order to improve the display quality of the liquid crystal display device, it is necessary to prevent contamination of the liquid crystal and the alignment film.

However, the spacer particle dispersion liquid discharged to the substrate may contain impurities, and the liquid crystals and the alignment film may be contaminated by the impurities. In this case, display quality such as color tone and contrast cannot be sufficiently improved.

Also, if the spacer particles are poorly dispersed in the spacer particle dispersion or if impurities are contained in the spacer particle dispersion, the spacer particles are applied to the substrate during the drying process of the droplets discharged onto the substrate. In some cases, the spacer particles are difficult to be fixed, and the spacer particles are not disposed under the light shielding region.

The object of the present invention is to take into account the current state of the prior art described above, and by using an inkjet device, spacer particles can be arranged at positions corresponding to non-pixel regions on a substrate, and contamination of liquid crystals and alignment films is suppressed. Another object of the present invention is to provide a manufacturing method of a liquid crystal display device, a spacer particle dispersion, and a liquid crystal display device.

A method for manufacturing a liquid crystal display device according to the present invention is a method for manufacturing a liquid crystal display device having a pixel region and a non-pixel region, using an inkjet device on the surface of a first substrate or a second substrate, A step of disposing spacer particles at a specific position corresponding to the non-pixel region by discharging a spacer particle dispersion in which spacer particles are dispersed in the medium, and the first substrate and the second substrate, A step of superposing the liquid crystal and the spacer particles so as to face each other, and in the step of superposing the liquid crystal and the spacer particles so as to face each other, before and after disposing the liquid crystal, the volume resistance value change rate of the liquid crystal Is 1% or more, and the change in nematic / isotropic phase transition temperature of the liquid crystal is within ± 1 ° C.
The spacer particle dispersion used in such a method for producing a liquid crystal display device of the present invention is also one aspect of the present invention.

In a specific aspect of the method for producing a liquid crystal display device according to the present invention, the spacer particles dispersed in the spacer particle dispersion are surface-modified by graft polymerization, and the spacer particle dispersion having a particle size of less than 1 μm The content ratio of the non-volatile components present in the liquid is less than 0.001% by weight with respect to 100% by weight of the spacer particle dispersion.

The spacer particle dispersion of the present invention is a spacer particle dispersion used when spacer particles are arranged on the surface of a substrate using an ink jet device, and contains at least spacer particles and a medium. The particles are surface-modified by graft polymerization, and the content ratio of nonvolatile components having a particle size smaller than 1 μm is less than 0.001% by weight.

The liquid crystal display device of the present invention is characterized by using the liquid crystal display device manufacturing method of the present invention or the spacer dispersion liquid of the present invention.

In the present invention, before and after disposing the liquid crystal, the volume resistance change rate of the liquid crystal is 1% or more, and the change in nematic / isotropic phase transition temperature of the liquid crystal is within ± 1 ° C. Is prevented. Therefore, the display quality such as the color tone and contrast of the liquid crystal display device is hardly deteriorated.

When the spacer particles dispersed in the spacer particle dispersion are surface-modified by graft polymerization, the density of the surface layer of the spacer particles is increased and a sufficiently thick surface layer is formed. Therefore, the dispersibility of the spacer particles in the spacer particle dispersion is improved, and the spacer particles are excellently fixed to the substrate when discharged onto the substrate. Therefore, it is easy to arrange the spacer particles at positions corresponding to the non-pixel regions on the substrate.

When the content ratio of the non-volatile components present in the spacer particle dispersion having a particle size smaller than 1 μm is less than 0.001% by weight with respect to 100% by weight of the spacer particle dispersion, a liquid crystal or alignment film However, the display quality such as contrast of the liquid crystal display device can be improved.

Details of the present invention will be described below.
FIG. 1 is a front sectional view schematically showing a liquid crystal display device obtained by a method for manufacturing a liquid crystal display device according to an embodiment of the present invention.

As shown in FIG. 1, in the liquid crystal display device 1, the 1st, 2nd board | substrates 2 and 3 which consist of transparent substrates are facing. As in the case of the conventional liquid crystal display device 200 shown in FIG. 9, the color filter 4 and the black matrix 5 are formed on the inner surface of the first substrate 1. An overcoat layer 6 is formed so as to cover the color filter 4 and the black matrix 5. A transparent electrode 7 is formed on the overcoat layer 6. An alignment film 8 is formed so as to cover the transparent electrode 7.

On the other hand, a transparent electrode 9 is formed on the inner surface of the second substrate 3 at a position facing the color filter 4. An alignment film 10 is formed so as to cover the transparent electrode 9.

Note that polarizing plates 11 and 12 are laminated on the outer surfaces of the first and second substrates 2 and 3, respectively.

The 1st board | substrate 2 and the 2nd board | substrate 3 are joined via the sealing material 13 by each outer periphery vicinity. A liquid crystal 15 is sealed in a space surrounded by the first substrate 2 and the second substrate 3. A plurality of spacer particles 14 are arranged at positions corresponding to the black matrix 6, that is, non-pixel regions. Therefore, the distance between the first and second substrates 2 and 3 is regulated by the spacer particles 14, and an appropriate thickness of the liquid crystal layer is maintained.

(Spacer particles)
The material of the spacer particles used in the present invention is not particularly limited, and may be inorganic particles such as silica particles or organic particles such as organic polymers. Among them, the organic particles have an appropriate hardness that does not damage the alignment film formed on the substrate of the liquid crystal display device, can easily follow a change in thickness due to thermal expansion and contraction, and are further spacer particles inside the cell. Is preferably used because it has the advantage of relatively little movement.

Although it does not specifically limit as said organic type particle | grain, Usually, since intensity | strength etc. exist in the suitable range, the copolymer of a monofunctional monomer and a polyfunctional monomer is used preferably. At this time, the ratio of the monofunctional monomer to the polyfunctional monomer is not particularly limited, and is appropriately adjusted depending on the strength and hardness required for the obtained organic particles.

Examples of the monofunctional monomer include styrene derivatives such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and chloromethylstyrene; vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; acrylonitrile. Unsaturated nitriles such as: methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, ethylene glycol (meth) acrylate And (meth) acrylic acid ester derivatives such as trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, and cyclohexyl (meth) acrylate. These monofunctional monomers may be used alone or in combination of two or more.

Examples of the polyfunctional monomer include divinylbenzene, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolpropanetetra (meta ) Acrylate, diallyl phthalate and its isomers, triallyl isocyanurate and its derivatives, trimethylolpropane tri (meth) acrylate and its derivatives, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (Meth) acrylate, polyethylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, etc. Ripropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 2,2-bis [4- (methacrylic) 2,2-bis [4- (methacryloxypolyethoxy) phenyl] propane di (meth) acrylate such as loxyethoxy) phenyl] propanedi (meth) acrylate, 2,2-hydrogenated bis [4- (acryloxypolyethoxy) Phenyl] propane di (meth) acrylate, 2,2-bis [4- (acryloxyethoxypolypropoxy) phenyl] propane di (meth) acrylate, and the like. These polyfunctional monomers may be used independently and 2 or more types may be used together.

Further, as the monofunctional or polyfunctional monomer, a monomer having a hydrophilic group may be used in order to increase dispersibility in the ink. Examples of the hydrophilic group include a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonyl group, an amino group, an amide group, an ether group, a thiol group, and a thioether group.

As monomers having such a hydrophilic group, 2-hydroxyethyl (meth) acrylate, 1,4-hydroxybutyl (meth) acrylate, (poly) caprolactone-modified hydroxyethyl (meth) acrylate, allyl alcohol, glycerin Monomers having a hydroxyl group such as monoallyl ether; acrylic acids such as (meth) acrylic acid, α-ethylacrylic acid and crotonic acid, and α- or β-alkyl derivatives thereof; fumaric acid, maleic acid, citracone Unsaturated dicarboxylic acids such as acids and itaconic acids; monomers having a carboxyl group such as mono 2- (meth) acryloyloxyethyl ester derivatives of these unsaturated dicarboxylic acids; t-butylacrylamidesulfonic acid, styrenesulfonic acid, 2 -Acrylamide-2-methylpropanesulfonic acid, etc. Monomers having a sulfonyl group; Monomers having a phosphonyl group such as vinyl phosphate and 2- (meth) acryloyloxyethyl phosphate; Amino groups such as amines having an acryloyl group such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate A compound having both a hydroxyl group and an ether group such as (poly) ethylene glycol (meth) acrylate and (poly) propylene glycol (meth) acrylate; a terminal alkyl ether of (poly) ethylene glycol (meth) acrylate , Monomers having an ether group such as (poly) propylene glycol (meth) acrylate terminal alkyl ether, tetrahydrofurfuryl (meth) acrylate, etc .; (meth) acrylamide, methylol (meth) acrylate Amides, monomer having a amide group such as vinyl pyrrolidone.

The method for producing particles by polymerizing the monomer is not particularly limited, and examples thereof include various polymerization methods such as a suspension polymerization method, a seed polymerization method, and a dispersion polymerization method.

In the suspension polymerization method, since the particle size distribution of the obtained particles is relatively wide and polydisperse particles are obtained, when used as spacer particles, classification operation is performed to obtain a desired particle size or particle size distribution. It is suitably used when obtaining various types of particles. On the other hand, seed polymerization and dispersion polymerization can be suitably used when producing a large amount of particles having a specific particle diameter because monodispersed particles can be obtained without going through a classification step.

The suspension polymerization method is a method in which a monomer composition comprising a monomer and a polymerization initiator is dispersed and polymerized in a poor solvent so as to have a target particle size. As the dispersion medium used for the suspension polymerization, a solution obtained by adding a dispersion stabilizer to water is usually used. Examples of the dispersion stabilizer include polymers soluble in the medium, such as polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylamide, and polyethylene oxide. Nonionic or ionic surfactants are also used as appropriate. The polymerization conditions vary depending on the polymerization initiator and the type of monomer, but the polymerization temperature is usually 50 to 80 ° C. and the polymerization time is 3 to 24 hours.

The seed polymerization method is a polymerization method in which a monodispersed seed particle synthesized by soap-free polymerization or emulsion polymerization is further expanded to a target particle size by further absorbing a monomer. The organic monomer used for the seed particles is not particularly limited, and the above-mentioned monomers are used. The composition of the seed particles is a monomer for seed polymerization in order to suppress phase separation during seed polymerization. A monomer having an affinity for the component is preferred, and styrene and its derivatives are preferred from the viewpoint of monodispersity of the particle system distribution.

Since the particle size distribution of the seed particles is also reflected in the particle size distribution after seed polymerization, it is preferably monodispersed as much as possible, and the Cv value is preferably 5% or less. As described above, phase separation from the seed particles is likely to occur during seed polymerization. Therefore, the monomer absorbed during seed polymerization is preferably as close to the seed particle composition as possible. If the seed particles are styrene, aromatic divinyl is used. In the case of a monomer or acrylic, it is preferable to polymerize by absorbing an acrylic polyfunctional vinyl monomer.

In the seed polymerization method, a dispersion stabilizer can be used as necessary. The dispersion stabilizer is not particularly limited as long as it is a polymer soluble in the medium, and examples thereof include polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylamide, and polyethylene oxide. Nonionic or ionic surfactants are also used as appropriate.

In the seed polymerization method, it is preferable to add 20 to 100 parts by weight of the monomer with respect to 1 part by weight of the seed particles.

The medium used for the seed polymerization is not particularly limited and should be appropriately determined depending on the monomer used. Generally, suitable organic solvents include alcohols, cellosolves, ketones or hydrocarbons. Furthermore, these can be used alone or as a mixed solvent with other organic solvents, water, etc. which are compatible with each other. Specifically, for example, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, alcohols such as ethyl acetate, methanol, ethanol and propanol, cellosolves such as methyl cellosolve and ethyl cellosolve, acetone, methyl ethyl ketone and methyl butyl ketone And ketones such as 2-butanone.

The above dispersion polymerization method is a polymerization in a poor solvent system in which the monomer is dissolved but the generated polymer is not dissolved, and the resulting polymer is precipitated in a particle shape by adding a polymer dispersion stabilizer to this system. It is a method to make it.

In general, when the cross-linking component is polymerized by dispersion polymerization, the particles tend to aggregate and it is difficult to stably obtain monodisperse cross-linked particles. However, by selecting the conditions, the monomer containing the cross-linking component is polymerized. It becomes possible to do.

In the polymerization, a polymerization initiator is used, and is not particularly limited. For example, benzoyl peroxide, lauroyl peroxide, benzoyl peroxide, benzoyl orthomethoxybenzoate, 3,5,5-trimethylhexanoyl peroxide, Organic peroxides such as t-butylperoxy-2-ethylhexanoate and di-t-butylperoxide, azobisisobutyronitrile, azobiscyclohexacarbonitrile, azobis (2,4-dimethylvaleronitrile) An azo compound such as) is preferably used. In general, the amount of the polymerization initiator used is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer used in the polymerization.

The particle diameter of the spacer particles used in the present invention is not particularly limited because it can be appropriately selected depending on the type of the liquid crystal display element. If the thickness is less than 1 μm, the opposing substrates may come into contact with each other and may not sufficiently function as a spacer of the liquid crystal display element. As a result, the distance between the opposing substrates is increased, making it impossible to sufficiently meet the recent demands for downsizing liquid crystal display elements.

Since the spacer particles used in the present invention are used as a gap material for maintaining an appropriate thickness of the liquid crystal layer, a certain strength is required. As an index indicating the compressive strength of the particles, when expressed by a compressive elastic modulus (10% K value) when the diameter of the particles is displaced by 10%, in order to maintain an appropriate thickness of the liquid crystal layer, 2000 to 15000 MPa is used. Is preferred. When the pressure is less than 2000 MPa, the spacer particles are deformed by the press pressure when assembling the display element, and an appropriate gap is hardly generated. If it is greater than 15000 MPa, the display film may be damaged due to damage to the alignment film on the substrate when incorporated in the display element.

The compression elastic modulus (10% K value) of the spacer particles is a value determined according to the method described in JP-T-6-503180. For example, using a micro compression tester (PCT-200, manufactured by Shimadzu Corporation), a smooth end face of a diamond column having a diameter of 50 μm is used to determine the weight for straining the particles by 10%.

The spacer particles obtained by the above method may be colored and used for improving the contrast of the display element. As colored particles, for example, particles treated with carbon black, disperse dyes, acid dyes, basic dyes, metal oxides, etc., and organic films are formed on the surface of the particles, and decomposed or carbonized at high temperatures. And colored particles. In addition, when the material itself which forms particle | grains has a color, you may use as it is, without coloring.

The spacer particles may be subjected to a chargeable process. The chargeable treatment is treatment in which the spacer particles have some potential in the spacer particle dispersion, and this potential (charge) can be measured by an existing method such as a zeta potential measuring device.

Examples of a method for performing chargeable treatment include a method in which a charge control agent is contained in spacer particles, a method in which spacer particles are produced from a monomer containing a monomer that is easily charged, and a surface in which spacer particles can be charged. The method of processing etc. are mentioned.

In addition, when the spacer particles can be charged in this manner, the dispersibility and dispersion stability of the spacer particles in the spacer particle dispersion liquid are improved, and the spacer particles are located near the wiring portion (step) portion by the electrophoretic effect when sprayed. Makes it easier to get together.

As a method of containing the charge control agent, there are a method in which the charge control agent is allowed to coexist when polymerizing the spacer particles and the polymerization is performed in the spacer particles, and a monomer constituting the spacer particles when the spacer particles are polymerized. A charge control agent having a functional group copolymerizable with a monomer that is copolymerized with a monomer constituting the spacer particle and contained in the spacer particle, a monomer used for surface modification in the surface modification of the spacer particle described later A charge control agent having a functional group copolymerizable with the surface modification layer by copolymerization, charged particles having a functional group opposite to the surface modification layer or the surface functional group of the spacer particle are reacted and contained on the surface And the like.

Although it does not specifically limit as said charge control agent, For example, the method of Unexamined-Japanese-Patent No. 2002-148865 can be used. Specifically, for example, organometallic compounds, chelate compounds, monoazo dye metal compounds, acetylacetone metal compounds, aromatic hydroxyl carboxylic acids, aromatic mono and polycarboxylic acids and their metal salts, anhydrides, esters, bisphenols, etc. Phenol derivatives and the like.

Further, the charge control agent is not particularly limited, but urea derivatives, metal-containing salicylic acid compounds, quaternary ammonium salts, calixarene, silicon compounds, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene- Acrylic-sulfonic acid copolymer, non-metallic carboxylic acid compound, modified product with nigrosine and fatty acid metal salt, etc., quaternary such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate Ammonium salts and onium salts such as phosphonium salts which are analogs thereof and lake pigments thereof, triphenylmethane dyes and lake lake pigments (the rake agents include phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdenum Acid, tan Acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids, diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide, dibutyltin borate, dioctyltin And diorganotin borates such as borate and dicyclohexyl tin borate.

These charge control agents may be used alone or in combination of two or more.

The polarity of the spacer particles containing the charge control agent can be set by appropriately selecting an appropriate charge control agent from the charge resistance control agent. That is, the spacer particles can be charged positively or negatively with respect to the surrounding environment.

When manufacturing the spacer particles, as a method for selecting a monomer appropriately from monomers including a monomer that is easily charged, a hydrophilic functional group is used as the monomer described in the section for manufacturing the spacer particles. The method of using what it has in combination is mentioned. By appropriately selecting an appropriate monomer from these monomers having a hydrophilic functional group, the spacer particles can be charged positively or negatively with respect to the surrounding environment. .

The spacer particles are preferably subjected to a surface treatment for improving adhesion to the substrate. Examples of the method for modifying the surface of the spacer particles include, for example, a method in which a resin is deposited on the surface of the spacer particles as disclosed in JP-A-1-247154, JP-A-9-11915, and the like. As disclosed in Kaihei 7-300587, a method of modifying by acting a compound that reacts with a functional group on the surface of spacer particles, as described in JP-A-11-223811, Japanese Patent Application No. 2002-102848 Although the method etc. which carry out graft polymerization on the spacer particle | grain surface and performing surface modification etc. are mentioned, When performing these, the method that a spacer particle | grain is charged is selected suitably.

As a method for modifying the surface of the spacer particles, a method of forming a surface layer chemically bonded to the surface of the spacer particles is preferable because there are few problems such as peeling of the surface layer and elution into the liquid crystal in the cell of the liquid crystal display device.

Of these, the method of performing graft polymerization described in JP-A-11-223821 is preferred. In the method of performing graft polymerization, particles having a reducing group on the surface of spacer particles are reacted with an oxidizing agent, radicals are generated on the surfaces of spacer particles, and the surface is graft-polymerized. When the graft polymerization is performed, the density of the surface layer of the spacer particles can be increased, and a sufficiently thick surface layer can be formed. Therefore, the graft-polymerized spacer particles are excellent in dispersibility in a spacer particle dispersion described later. Furthermore, when the spacer particle dispersion is discharged onto the substrate, the spacer particles are excellent in adhesion to the substrate. In order to perform the charging treatment in this method, it is preferable to use a monomer having a hydrophilic functional group in combination as a monomer when performing graft polymerization.

In addition, by performing the surface treatment in this way, there is an effect that the adhesion of the spacer particles to the substrate is increased, or if the monomer to be used is appropriately selected, the alignment of the liquid crystal in the liquid crystal display body is not disturbed. . Therefore, the surface modification may be performed on the spacer particles regardless of the presence or absence of the charging treatment.

The spacer particles are preferably surface-modified by grafting. Specifically, a vinyl thermoplastic resin obtained by radical polymerization of a vinyl monomer having a hydrophilic functional group and / or an alkyl group having 3 to 22 carbon atoms is bonded to the surface of the spacer particle by graft polymerization. It is preferable.

The hydrophilic functional group is not particularly limited, and examples thereof include a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonyl group, an amino group, an amide group, an ether group, a thiol group, and a thioether group. Since there is little interaction, a hydroxyl group, a carboxyl group, and an ether group are preferably used. These hydrophilic functional groups may be used alone or in combination of two or more.

The vinyl monomer having a hydrophilic functional group is not particularly limited. For example, 2-hydroxyethyl (meth) acrylate, 1,4-hydroxybutyl (meth) acrylate, (poly) caprolactone-modified hydroxyethyl (meta ) Vinyl monomers having a hydroxyl group such as acrylate, allyl alcohol, glycerin monoallyl ether; acrylic acid such as (meth) acrylic acid, α-ethylacrylic acid, crotonic acid, and their α-alkyl derivatives or β-alkyl Derivatives; Unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid; vinyl monomers having a carboxyl group such as mono 2- (meth) acryloyloxyethyl ester derivatives of the above unsaturated dicarboxylic acids; t -Butylacrylamide sulfonic acid, styrene sulfone , Vinyl monomers having a sulfonyl group such as 2-acrylamido-2-methylpropanesulfonic acid; vinyl monomers having a phosphonyl group such as vinyl phosphate and 2- (meth) acryloyloxyethyl phosphate; dimethylaminoethyl Vinyl-based monomers having amino groups such as methacrylate and diethylaminoethyl methacrylate; terminal alkyl ether of (poly) ethylene glycol (meth) acrylate, terminal alkyl ether of (poly) propylene glycol (meth) acrylate, tetrahydrofurfuryl (meta ) Vinyl monomers having an ether group such as acrylate; vinyl groups having a hydroxyl group and an ether group such as (poly) ethylene glycol (meth) acrylate and (poly) propylene glycol (meth) acrylate Mer; (meth) acrylamide, methylol (meth) acrylamide, vinyl monomers having a amide group such as vinyl pyrrolidone. These vinyl monomers having a hydrophilic functional group may be used alone or in combination of two or more.

It does not specifically limit as said C3-C22 alkyl group, For example, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, n- Hexyl group, cyclohexyl group, 2-ethylhexyl group, n-heptyl group, n-octyl group, n-nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, nonadecyl group, eicodecyl group, Examples include henicosyl group, docosyl group, isobornyl group and the like. These C3-C22 alkyl groups may be used independently and 2 or more types may be used together.

The vinyl monomer having an alkyl group having 3 to 22 carbon atoms is not particularly limited. For example, an ester compound composed of (meth) acrylic acid and the alkyl group having 3 to 22 carbon atoms; vinyl alcohol and the above Examples thereof include ester compounds composed of an alkyl group having 3 to 22 carbon atoms; vinyl ether compounds composed of a vinyl group and the above alkyl group having 3 to 22 carbon atoms. These vinyl monomers having a C 3-22 alkyl group may be used alone or in combination of two or more. The vinyl monomer having a hydrophilic functional group and the vinyl monomer having an alkyl group having 3 to 22 carbon atoms may be used alone or in combination.

The vinyl monomer constituting the vinyl thermoplastic resin is a vinyl monomer having 30 to 80% by weight of the vinyl monomer having the hydrophilic functional group and the alkyl group having 3 to 22 carbon atoms. It is preferable to contain 20 to 60% by weight of the monomer.

When the content of the vinyl monomer having a hydrophilic functional group in the vinyl monomer is less than 30% by weight, the spacer particle dispersion medium containing the obtained spacer particles is sufficiently single-particled It becomes difficult to disperse in the liquid, and aggregated particles are likely to be generated, and stable ejection with an ink jet device may be difficult, and the cell gap may not be formed accurately. When the content of the vinyl monomer having a hydrophilic functional group exceeds 80% by weight, abnormal alignment of the liquid crystal occurs on the surface of the spacer particles protruding into the display pixel when the cell of the liquid crystal display device is formed. May lead to a decrease in display quality.

Further, when the content of the vinyl monomer having an alkyl group having 3 to 22 carbon atoms in the vinyl monomer is less than 20% by weight, when the cell of the liquid crystal display device is formed, It is easy to cause abnormal alignment of the liquid crystal on the surface of the protruding spacer, which may lead to a decrease in display quality. Conversely, a vinyl monomer having an alkyl group having 3 to 22 carbon atoms in the vinyl monomer. When the body content exceeds 60% by weight, the dispersion stability of the obtained spacer particles in the medium may be lowered.

The spacer particles are bonded by graft polymerization with a vinyl thermoplastic resin obtained by radical polymerization of the vinyl monomer having the hydrophilic functional group and / or the alkyl group having 3 to 22 carbon atoms on the surface of the spacer particles. When laminating a plurality of vinyl-based thermoplastic resin layers having different compositions for the purpose of increasing the thickness of the surface coating layer of the particles, 30 to 80% by weight of the vinyl-based monomer having the hydrophilic functional group and The use of a preferred vinyl monomer comprising 20 to 60% by weight of a vinyl monomer having an alkyl group having 3 to 22 carbon atoms is only for the vinyl thermoplastic resin which is the outermost layer of the surface coating layer. Consider it. This is because the functions such as the dispersibility of the spacer particle dispersion and the medium used in the ink-jet ink and the suppression of abnormal liquid crystal orientation are manifested by the state near the surface of the spacer.
By performing such a surface treatment, spacer movement is eliminated in an impact test or the like after the panel is manufactured.

(Spacer particle dispersion)
In the present invention, in the spacer particle dispersion, the above-described spacer particles are dispersed in a medium in which the spacer particles can be dispersed.

As the medium for the spacer particle dispersion, for example, various solvents that are liquid at the temperature discharged from the head are used. Of these, a water-soluble or hydrophilic solvent is preferable. In addition, since the heads of some ink jet devices are made for aqueous media, when these heads are used, a solvent having a strong hydrophobic property may cause the member constituting the head to be affected by the solvent or to adhere the member. This is not preferable because a part of the adhesive may be dissolved.

Examples of the water-soluble or hydrophilic solvent include water, ethanol, n-propanol, 2-propanol, 1-butanol, 2-butanol, 1-hexanol, 1-methoxy-2-propanol, furfuryl alcohol, tetrahydro Monoalcohols such as furfuryl alcohol, multimers of ethylene glycol such as ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol; multimers of propylene glycol such as propylene glycol, dipropylene glycol, tripropylene glycol, and tetrapropylene glycol Lower monoalkyl ethers of glycols such as monomethyl ether, monoethyl ether, monoisopropyl ether, monopropyl ether, monobutyl ether; Lower dialkyl ethers such as ter, diethyl ether, diisopropyl ether and dipropyl ether; alkyl esters such as monoacetate and diacetate, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 3-hexene-2,5-diol, 1,5-pentanediol, 2,4-pentanediol, 2-methyl-2,4- Diols such as pentanediol, 2,5-hexanediol, 1,6-hexanediol, neopentylglycol, ether derivatives of diols, acetate derivatives of diols, glycerin, 1,2,4-butanetriol, 1, 2,6-hexanetriol, 1,2,5-pentanetriol, tri Polyhydric alcohols such as tyrolpropane, trimethylolethane, pentaerythritol or ether derivatives thereof, acetate derivatives, dimethyl sulfoxide, thiodiglycol, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidine, sulfolane, formamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylformamide, acetamide, N-methylacetamide, α-terpineol, ethylene carbonate, propylene carbonate Bis-β-hydroxyethylsulfone, bis-β-hydroxyethylurea, N, N-diethylethanolamine, abietinol, diacetone alcohol, urea and the like.

In the present invention, it is preferable that the surface tension of the spacer particle dispersion is 33 mN / m or more by combining the above-described solvents. When the surface tension is 33 mN / m or more, the droplet diameter of the spacer particle dispersion liquid that has landed on the substrate becomes small.

In the present invention, the spacer particle dispersion may contain a solvent having a boiling point of 100 ° C. or higher. More preferably, an organic solvent having a boiling point of 70 ° C. or higher and lower than 100 ° C. is included.
In addition, the boiling point as used in the field of this invention means the boiling point on 1 atmosphere conditions.

As the solvent having a boiling point of less than 100 ° C., for example, lower monoalcohols such as ethanol, n-propanol and 2-propanol, acetone and the like are preferably used.

When spraying the spacer particle dispersion and drying the solvent, if the medium comes into contact with the alignment film at a high temperature, the alignment film is contaminated and the display image quality of the liquid crystal display device is impaired. However, since the drying temperature can be lowered by using a solvent having a temperature lower than 100 ° C. as described above, the alignment film is not contaminated.

A solvent having a boiling point of less than 100 ° C. has a preferable lower limit of 1.5% by weight and a preferable upper limit of 80% by weight with respect to 100% by weight of the spacer particle dispersion excluding the spacer particles. If the solvent having a boiling point of less than 100 ° C. is less than 1.5% by weight, the drying rate as a dispersion at a relatively low drying temperature applied in the present invention is slow, and production efficiency is lowered, which is not preferable. Further, if the solvent having a boiling point of less than 100 ° C. exceeds 80% by weight, the surface tension of the spacer dispersion becomes too low, and the droplets become too wide when landing on the substrate, making it difficult for the spacers to collect, The nearby spacer particle dispersion is liable to dry, and ink jetting properties may be impaired. Furthermore, it may be easy to dry in the production of the spacer particle dispersion or in the tank, and as a result, there is a high possibility that aggregated particles are generated.

The solvent having a boiling point of less than 100 ° C. preferably has a surface tension at 20 ° C. of 38 mN / m or less, more preferably 25 mN / m or less. When the surface tension of the solvent is larger than 38 mN / m, the dischargeability by the ink jet apparatus may be deteriorated. In addition, it is preferable that the surface tension in 20 degreeC of the solvent whose boiling point is 100 degreeC or more is 38 mN / m or more.

Since the spacer particle dispersion contains a solvent having a boiling point of less than 100 ° C. and a surface tension of 38 mN / m or less, the spacer particle dispersion can be easily introduced into an ink jet apparatus to be described later. Can be improved.

As described above, the spacer particle dispersion liquid may contain a solvent having a boiling point of less than 100 ° C. and a solvent having a boiling point of 100 ° C. or higher. The solvent having a boiling point of 100 ° C. or higher is preferably a mixture of water and a solvent having a boiling point of 150 ° C. or higher, and more preferably a mixture of water and a solvent having a boiling point of 150 ° C. or higher and 200 ° C. or lower.

In the present invention, it becomes easy to set the receding contact angle to 5 degrees or more by mixing a solvent having a boiling point of 150 ° C. or more and a surface tension of 38 mN / m or more. That is, after the droplets of the spacer particle dispersion liquid land on the substrate, the low surface tension solvent with a boiling point of less than 100 ° C. is volatilized first, and the surface tension of the remaining dispersion liquid becomes high and moves toward the center of the landing point. It is preferable because all the spacer particles easily move.

Conversely, if the surface tension of the solvent having a boiling point of 150 ° C. or higher is less than 38 mN / m, after the droplet of the spacer particle dispersion has landed on the substrate, the solvent having a boiling point of less than 100 ° C. Since it volatilizes, the surface tension of the remaining dispersion becomes lower than the initial. Therefore, the landing droplet diameter is not reduced, the landing droplet diameter is easily expanded from the initial stage, and the spacer particles are difficult to move toward the center of the landing point.

Specific examples of the solvent having a boiling point of 150 ° C. or higher include lower alcohol ethers such as ethylene glycol, diethylene glycol, propylene glycol, and 1,2-butanediol. Such a solvent prevents the dispersion of the spacer particle dispersion from being excessively dried in the vicinity of the nozzles of the ink jet apparatus and lowering the discharge accuracy. Further, since the spacer particle dispersion is produced or dried in a tank, the generation of aggregated particles is suppressed.

The ratio of the solvent having a boiling point of 150 ° C. or higher in the medium of the spacer particle dispersion is preferably in the range of 0.1 to 95% by weight, more preferably 0.2 to 90% by weight. If the ratio of the solvent is less than 0.1% by weight, it is not preferable because the discharge accuracy is lowered and the generation of aggregated particles is likely to occur due to drying of the dispersion liquid as described above. When the solvent ratio exceeds 95% by weight or the boiling point exceeds 200 ° C., not only the drying time is remarkably reduced but the efficiency is lowered, and the display image quality of the liquid crystal display device is liable to be deteriorated due to contamination of the alignment film.

As the spacer particle dispersion used in the present invention, those having a small amount of non-volatile components excluding spacer particles in the spacer particle dispersion are preferably used. Specific non-volatile components include those containing less non-volatile components such as dust in the atmosphere, impurities contained in the solvent used to disperse the spacer particles, pulverized spacer particles, and ionic non-volatile materials. Preferably used. The non-volatile component includes solids that do not have shape retention in the spacer particle dispersion, non-spherical fine particles, and extremely fine particles that do not contribute to maintaining the gap even when spherical.
Thus, by the spacer particle dispersion liquid with a small non-volatile component excluding the spacer particles, the volume resistivity change rate of the liquid crystal is 1% or more and the change of the nematic / isotropic phase transition temperature of the liquid crystal is within ± 1 ° C. A spacer particle dispersion can be obtained.
The change in the volume resistance value and the change in the nematic / isotropic phase transition temperature of the liquid crystal are, for example, changes before and after the spacer particle dispersion is discharged onto a substrate and dried and brought into contact with the liquid crystal.

The content ratio of the non-volatile component present in the spacer particle dispersion used in the present invention is preferably less than 0.001% by weight with respect to 100% by weight of the spacer particle dispersion. If the content ratio of the nonvolatile component is 0.001% by weight or more, the liquid crystal and the alignment film are contaminated, and the display quality such as contrast of the liquid crystal display device may be deteriorated.
A spacer particle dispersion used when arranging spacer particles on the surface of a substrate using such an ink jet apparatus, which contains at least spacer particles and a medium. A spacer particle dispersion that is modified and has a non-volatile component content of less than 0.001% by weight is also one aspect of the present invention.

As a method of reducing the non-volatile components in the spacer particle dispersion liquid and adjusting the non-volatile components to the above-mentioned content ratio, for example, a solvent from which impurities have been removed by precision distillation is used, or filtration that is first larger than the particle size of the spacer particles The spacer particle dispersion is filtered with a filter having a diameter to remove large dust, and then the spacer particle dispersion is centrifuged to precipitate the spacer particles. Then, the supernatant liquid is discarded, and the filtered spacer particles are further filtered. And a method of dispersing the spacer particles by adding a solvent filtered through a filter having a filtration diameter of 1 μm. Alternatively, the spacer particles are filtered by a filter having a filtration diameter smaller than the particle diameter of the spacer particles, and the filtered spacer particles are dispersed in a solvent filtered by a filter having a filtration diameter of 1 μm. The method used is also mentioned. These methods may be repeated. In addition, as an instrument to be used / stored when the non-volatile component is contained in the above-described content ratio, a device that causes less elution of non-volatile components such as ionic components and organic substances is used. Examples of the equipment to be used / stored include containers such as stainless steel, fluororesin, alkali-free glass, bloom-treated glass, and borosilicate glass.

As the ion-adsorptive solid, a layered inorganic compound is preferably used. The layered inorganic compound has a laminated structural unit having a certain property and a gap structure, so that it has high designability and function-imparting property, and has unique properties and functions such as two-dimensional physical properties and ion exchange. is doing.

By using the layered inorganic compound, metal atoms present between the layers of the layered inorganic compound trap ionic impurities. Further, since the layered inorganic compound has a layered structure, the ionic impurities once trapped and adsorbed are unlikely to elute again.

The layered inorganic compound is preferably a layered silicate mineral.

Examples of the layered silicate mineral include hydrotalcite group compounds, serpentine-kaolin group compounds, talc pyrophyllite group compounds, smectite group compounds, vermiculite group compounds, mica groups, interlayer-deficient mica compounds, and brittle mica. Group compounds, chlorite group compounds, mixed layer minerals, diatomaceous earth, aluminum silicate and the like, preferably hydrotalcite group compounds and serpentine-kaolin group compounds. The layered silicate mineral may be a naturally produced product or a synthesized product. These layered silicate minerals may be used alone or in combination of two or more.

As the hydrotalcite compound is preferably one represented by the following general formula (1), inter _{alia, Mg 6 Al 2 (OH)} 16 CO 3 · 4H 2 O are preferred.
Mg _n1 Al _n2 (OH) _r1 (CO ₃ ) _r2 · sH ₂ O (1)

In said formula (1), n1, n2, r1 and r2 represent an integer greater than or equal to 1.

Examples of the serpentine-kaolin group compounds include lizardite, burcerin, amesite, cronsteite, nepoite, keriaite, fraponite, brindriaite, kaolinite, dickite, nacrite, halosite (plate-like), audinite Etc.

Examples of the talc pyrophyllite group compound include talc, willemsite, kellolite, pimelite, pyrophyllite, ferripyrophyllite and the like.

Examples of the smectite group compound include sapoinite, hectorite, saconite, stevensite, swin holderite, montmorillonite, beidellite, nontronite, bolcon score.

Examples of the vermiculite group compound include 3 octahedral vermiculite, 2 octahedral vermiculite, and the like.

Examples of the mica group compound include biotite, phlogopite, iron mica, yeast knight, siderophyllite tetraferri iron mica, scale mica, polyriccionite, muscovite, celadonite, iron ceradonite, iron aluminoceradone. Stones, aluminoceradone stones, abrasive mica, soda mica and the like.

Examples of the interlaminar defect type mica compound include a dioctahedral type (illite, sea green stone, bramerlite), a trioctahedral type (wonnesite), and the like.

Examples of the brittle mica group compounds include clintonite, kinoshita, hide mica, ananda stone, and pearl mica.

Examples of the chlorite group compounds include clinochlore, chamosite, penantite, nimite, bailicroa, dombasite, kukeaite, and suedoite.

Examples of the mixed layer mineral include collensite, hydrobiotite, arietite, crucareite, rectolite, tosudite, dodrite, lnjanglite, salioite and the like.

The ion-adsorptive solid is preferably a granular solid so that it can be easily separated after contact with the spacer particle dispersion. Further, the shape of the ion-adsorbing solid is not particularly limited, and its particle size is preferably small for the purpose of increasing the chance of contact with the ionic impurities to be recovered, but it becomes a problem such as clogging during filtration. Therefore, it is preferably 2 μm or more.

As a method of reducing the non-volatile component in the spacer particle dispersion using the ion-adsorptive solid and making the non-volatile component the content ratio, the ion-adsorptive solid is passed as a cleaning solvent for cleaning the spacer particles. A method using a cleaning solvent from which ions have been removed, a method in which a dispersion of spacer particles before dispersing the spacer particles is passed through the ion-adsorptive solid to remove ions, and a spacer particle dispersion in which spacer particles are dispersed. Examples include a method of removing ions by passing through the ion-adsorbing solid.

In the spacer particle dispersion produced using the ion-adsorptive solid, ionic impurities such as sodium ion, potassium ion, chlorine ion, acrylic acid, and methacrylic acid are removed, and these flow out into the liquid crystal. Can be prevented.

Further, as the spacer particle dispersion liquid, a spacer particle dispersion liquid having a receding contact angle (θr) with respect to the substrate to be discharged of 5 degrees or more is preferably used. If the receding contact angle is 5 degrees or more, the droplets of the spacer particle dispersion that have landed on the substrate dries and shrinks toward the center, and at least one spacer particle contained in the droplets. It is possible to gather near the center of the droplet. Further, when the charged ink is ejected there, the spacer particles are more easily moved to the landing point of the charged ink by the force acting electrostatically, and the arrangement accuracy of the spacer particles is further improved.

When the receding contact angle (θr) is less than 5 degrees, the droplets are dried around the center (landing center) where the droplets land on the substrate, the droplet diameter is reduced, and the spacer particles It becomes difficult to gather at the center.

Here, the receding contact angle refers to the landing of the droplet of the spacer particle dispersion placed on the substrate when it is first placed on the substrate in the process from placing on the substrate to drying. It refers to the contact angle shown when it becomes smaller than the diameter (when the droplet starts to shrink), or the contact angle shown when 80 to 95% by weight of the volatile components of the droplet are volatilized.

Examples of the method for adjusting the receding contact angle to 5 ° or more include a method for adjusting the composition of the dispersion medium of the spacer particle dispersion liquid and a method for adjusting the surface of the substrate.

In order to adjust the composition of the dispersion medium of the spacer particle dispersion, a medium having a receding contact angle of 5 degrees or more may be used alone, or two or more kinds of media may be mixed and used. It is preferable to use a mixture of two or more types because it is easy to adjust the dispersibility of the spacer particles, the workability of the spacer particle dispersion, the drying speed, and the like.

When two or more solvents are mixed and used as the spacer particle dispersion, the spacer particles are mixed so that the receding contact angle (θr) of the solvent having the highest boiling point is 5 degrees or more. It is preferable. If the receding contact angle (θr) of the solvent having the highest boiling point is less than 5 degrees, the droplet diameter increases in the late stage of drying (droplet spreads on the substrate), and the spacer particles gather on the landing center on the substrate. It becomes difficult.

The receding contact angle tends to be smaller than the so-called contact angle (the initial contact angle when a droplet is placed on a substrate, which is usually called the contact angle in most cases). This is because the initial contact angle is the contact angle of the droplet with respect to the substrate on the surface of the substrate not in contact with the solvent constituting the spacer particle dispersion, whereas the receding contact angle constitutes the spacer particle dispersion. This is considered to be due to the contact angle of the droplet with respect to the substrate on the surface of the substrate after contacting with the solvent. That is, when the receding contact angle is remarkably lower than the initial contact angle, it indicates that the alignment film is damaged by those solvents. , It was not preferable.

The spacer particle dispersion is preferably adjusted so that the initial contact angle θ between the spacer particle dispersion and the substrate surface is 10 to 110 degrees. When the initial contact angle between the spacer particle dispersion and the substrate surface is less than 10 degrees, the spacer particle dispersion droplets discharged on the substrate are wet and spread on the substrate, and the arrangement interval of the spacer particles cannot be reduced. If the angle is greater than 110 degrees, the droplets easily move around on the substrate with a slight vibration, resulting in a problem that the placement accuracy is deteriorated and the adhesion between the spacer particles and the substrate is deteriorated.

The viscosity at the time of discharging the spacer particle dispersion in the present invention is preferably in the range of 0.5 to 15 mPa · s, more preferably in the range of 5 to 10 mPa · s. If the viscosity at the time of discharge is higher than 15 mPa · s, the ink jet device may not be able to discharge, and if it is lower than 0.5 mPa · s, it can be discharged stably even if it is possible to control the discharge amount. It may disappear. When discharging the spacer particle dispersion, the head temperature of the inkjet device is cooled by a Peltier element, a refrigerant, or the like, or heated by a heater or the like, so that the liquid temperature at the time of discharging the spacer particle dispersion is − You may adjust between 5 degreeC and 50 degreeC.

The solid content concentration of the spacer particles in the spacer particle dispersion is preferably in the range of 0.01 to 10% by weight, more preferably in the range of 0.1 to 3% by weight. If it is less than 0.01% by weight, the probability that the discharged droplets do not contain spacer particles increases, which is not preferable. In addition, if it exceeds 10% by weight, the nozzles of the ink jet apparatus may be blocked, and the number of spacer particles contained in the landed dispersed droplets will increase so that the movement of the spacer particles is difficult to occur during the drying process. It is not preferable.

The spacer particle dispersion according to the present invention preferably does not contain non-volatile substances that do not cause a change in volume resistivity or nematic / isotropic phase transition temperature in terms of cell gap and optical characteristics. It is preferable that the content of such a nonvolatile material is less than 0.001% by weight with respect to 100% by weight of the spacer particle dispersion according to the present invention. When the content of the nonvolatile material is 0.001% by weight or more, the liquid crystal and the alignment film are contaminated, and the display quality such as contrast of the liquid crystal display device may be inferior.

In the spacer particle dispersion, the spacer particles are preferably dispersed in a single particle form. The presence of aggregates in the dispersion liquid is not preferable because not only the discharge accuracy is lowered, but also the nozzles of the ink jet apparatus may be clogged in a remarkable case.

In the present invention, within the range that does not impair the effects of the present invention, the adhesive component for imparting adhesion to the spacer particle dispersion liquid, the dispersion of the spacer particles is improved, and the physical properties such as surface tension and viscosity are controlled. Various surfactants, viscosity modifiers, and the like may be added for the purpose of improving the discharge accuracy and improving the mobility of the spacer particles.

(Inkjet device)
Next, an ink jet apparatus used for discharging the spacer particle dispersion onto the substrate will be described.

The ink jet apparatus used in the present invention is not particularly limited. For example, a normal ejection method such as a piezo system that ejects a liquid by vibration of a piezo element or a thermal system that ejects a liquid by utilizing the expansion of the liquid by rapid heating. Is used. Among them, a piezo method that has little thermal influence on the discharged material such as spacer particle dispersion is preferably used.

It is preferable that the liquid contact portion of the ink chamber containing the spacer particle dispersion of the ink jet apparatus is made of a hydrophilic material having a surface tension of 31 mN / m or more. Note that the wetted part may be subjected to a hydrophilic treatment with a chemical solution or the like to obtain a hydrophilic material having a surface tension of 31 mN / m or more.
As the material, a hydrophilic organic material such as hydrophilic polyimide is used, or a head made of a material of a liquid contact part of a normal ink chamber is treated with a hydrophilizing agent (oxidized by the material of the liquid contact part). In addition, an inorganic material, that is, a metal material such as ceramics, glass, and stainless steel with low corrosiveness is preferably used.

In a normal head, resin or the like is used in this portion for insulation from a voltage application component. However, when such a material having a surface tension lower than 31 mN / m is used, a spacer particle dispersion is introduced into the head. Since the familiarity with the spacer particle dispersion is poor, bubbles are likely to remain, and if bubbles remain, the nozzle with bubbles remaining may not be ejected, which is not preferable.

The nozzle diameter of the ink jet device is preferably 5 times or more the spacer particle diameter. If it is less than 5 times, the nozzle diameter is too small compared to the particle diameter and the discharge accuracy is lowered, and if it is remarkable, the nozzle is blocked and discharge is not preferable. More preferably, it is 7 times or more.

The reason why the discharge accuracy is lowered is considered as follows. In the piezo method, ink is sucked into an ink chamber adjacent to the piezo element by vibration of the piezo element, or ink is ejected from the ink chamber through the tip of a nozzle. As a droplet discharge method, the meniscus (interface between ink and gas) at the tip of the nozzle is pulled in immediately before discharge, and then the liquid is pushed out and the liquid is pushed out directly from the position where the meniscus is on standby Although there is a method, in the general ink jet apparatus, the former striking method is the mainstream, and as a feature thereof, small droplets can be ejected. In the ejection of the spacer particles of the present invention, the diameter of the nozzle is somewhat large and the ejection of small droplets is required, so this striking method is effective.

However, in the case of the pulling method, the meniscus is drawn immediately before discharge, so that, for example, when the nozzle diameter is small such that the nozzle diameter is less than 5 times the particle diameter, the drawn meniscus is shown in FIG. If the spacer particles 21 are present in the vicinity of the meniscus 22, the meniscus 22 is not drawn in an axial symmetry. Therefore, it is considered that the droplets of the spacer particle dispersion liquid 23 are not straight but bent during the extrusion after the drawing, and the discharge accuracy is lowered. For example, when the nozzle diameter is large such that the nozzle diameter is 7 times or more of the particle diameter, even if the spacer particles 21 are in the vicinity of the drawn meniscus 22 as shown in FIG. Not affected. Therefore, it is considered that the meniscus 22 is drawn in an axisymmetric manner, and the liquid droplets of the spacer particle dispersion liquid 23 go straight in the push-out after the pull-in to improve the discharge accuracy. However, if the nozzle diameter is increased unnecessarily in order to eliminate the bending of the droplets during ejection, the ejected droplets become larger and the landing diameter becomes larger. Therefore, the accuracy with which the charged ink and spacer particles 21 are arranged is improved. It becomes rough and is not preferable.

The amount of droplets ejected from the nozzle is preferably in the range of 10 to 80 pL in the case of a spacer particle dispersion. As a method for controlling the droplet amount, there are a method for optimizing the nozzle diameter and a method for optimizing an electric signal for controlling the ink jet head. The latter is particularly important when a piezo ink jet apparatus is used.

In an ink jet apparatus, an ink jet head is provided with a plurality of nozzles as described above in a fixed arrangement. For example, 64 or 128 are provided at equal intervals in a direction orthogonal to the moving direction of the head. In some cases, these are provided in a plurality of rows such as two rows.

The interval between the nozzles is restricted by the structure of the piezoelectric element and the nozzle diameter. Therefore, when the spacer particle dispersion is discharged onto the substrate at intervals other than the intervals at which the nozzles are arranged, it is difficult to prepare a head for each of the discharge intervals. Accordingly, when the distance is smaller than the distance between the heads, the head, which is normally arranged at right angles to the scanning direction of the head, is discharged while being tilted or rotated in a plane parallel to the substrate while being parallel to the substrate. When the interval is larger than the interval between the heads, the discharge is not performed by all the nozzles, but is performed by discharging only a certain nozzle, or by additionally tilting the head.

In order to increase productivity, it is possible to attach a plurality of such heads to the ink jet apparatus. However, if the number of attachments is increased, the control becomes complicated, so care must be taken.

FIGS. 8A and 8B schematically show an example of a head of an ink jet apparatus used in the present invention. FIG. 8A is a partially cutaway perspective view schematically showing the structure of an example of an ink jet head, and FIG. 8B is a partially cutaway perspective view showing a cross section of the nozzle hole portion. As shown in FIGS. 8A and 8B, the head 100 includes an ink chamber 101 in which ink is filled in advance by suction or the like, and an ink chamber 102 into which ink is sent from the ink chamber 101. Yes. A nozzle hole 104 extending from the ink chamber 102 to the ejection surface 103 is formed in the head 100. The ejection surface 103 is previously subjected to water repellent treatment in order to prevent contamination with ink. The head 100 is provided with temperature control means 105 for adjusting the viscosity of the ink. The head 100 includes a piezo element 106 that functions to send ink from the ink chamber 101 to the ink chamber 102 and further functions to discharge ink from the nozzle hole 104.

Since the temperature control means 105 is provided in the head 100, when the viscosity is too high, the ink can be heated by a heater to reduce the viscosity of the ink, and when the viscosity is too low, the temperature can be reduced by Peltier. It is possible to increase the viscosity of the ink by cooling the ink.

(Substrate for liquid crystal display)
As a 1st, 2nd board | substrate for liquid crystal display devices used for this invention, what is normally used as a panel substrate of liquid crystal display devices, such as glass and resin, can be used. As the one substrate, a substrate in which a color filter is provided in a pixel region can be used. In this case, the pixel region is defined by a black matrix such as a resin in which a metal such as chrome or carbon black that hardly transmits light is dispersed. This black matrix constitutes a non-pixel region.

(Step of ejecting a spacer particle dispersion liquid in which spacer particles are dispersed using an ink jet apparatus to land droplets on the surface of the first substrate)
In the present invention, the spacer particle dispersion is discharged onto the surface of the first substrate or the second substrate using an inkjet device, and the spacer particles are arranged at positions corresponding to the non-pixel regions.

At this time, the location on the substrate where the droplets of the spacer particle dispersion are discharged and landed is adjusted so that the receding contact angle (θr) of the spacer particle dispersion is 5 degrees or more, or the spacer When the particle dispersion is a mixture composed of one or more solvents, the receding contact angle (θr) of the solvent having the highest boiling point among the solvents is preferably adjusted to be 5 degrees or more. In the case of charged ink, it is not necessary to adjust the receding contact angle to be 5 degrees or more as described above. However, there is no problem even if the receding contact angle is adjusted to 5 degrees or more.

Examples of the method of setting the receding contact angle to 5 degrees or more include a method of selecting the solvent of the spacer particle dispersion described above and a method of setting the surface of the substrate to a low energy surface.

As a method of setting the surface of the substrate to a low energy surface, a method of applying a resin having a low energy surface such as a fluorine film or a silicone film may be applied, but it is necessary to regulate the alignment of liquid crystal molecules on the surface of the substrate. Therefore, a method of providing a resin thin film (usually 0.1 μm or less) called an alignment film is generally performed. A polyimide resin film is usually used for these alignment films. The polyimide resin film is obtained by applying a polyamic acid soluble in a solvent and then thermally polymerizing it, or by applying a soluble polyimide resin and then drying. As these polyimide resins, those having a long side chain and a main chain are more preferable for obtaining a low energy surface. In order to control the alignment of the liquid crystal, the alignment film may be rubbed on the surface after coating. In addition, it is necessary to select the medium of the above-mentioned spacer particle dispersion liquid that does not contaminate the alignment film by permeating or dissolving in the alignment film.

In the present invention, the location where the spacer particle dispersion liquid is discharged and landed on the first substrate is preferably a low energy surface. Here, the position corresponding to the non-pixel region is the substrate on the non-pixel region (the above-described black matrix if a color filter substrate) or on the other substrate (TFT array substrate if a TFT liquid crystal panel). Is a region corresponding to the non-pixel region when the substrate is overlapped with the substrate having the non-pixel region (a wiring portion or the like in the case of a TFT array substrate).

The surface energy of the portion having a low energy surface is preferably 45 mN / m or less, more preferably 40 mN / m or less. If it exceeds 45 mN / m, as long as a spacer particle dispersion having a surface tension that can be discharged by an ink jet device is used, the droplets are likely to spread on the substrate, and the spacer particles may protrude from the non-pixel region. become.

The low energy surface obtained by applying an alignment film or the like may be only the location where the spacer particles land, or the entire surface of the substrate. Considering processes such as patterning, the entire surface is usually a low energy surface.

In the present invention, the first substrate to which the spacer particle dispersion is discharged has a portion having a low energy surface in a region corresponding to the non-pixel region, and the droplet after landing is a low energy surface. The droplets of the spacer particle dispersion liquid are landed so as to be present at the locations having, but there may be included locations having a step and a periphery. In addition, it is more preferable that the charged ink is discharged and dried only at a portion having a step.

Here, the step is an unintentional unevenness (level difference from the surroundings) caused by wiring provided on the substrate, or intentionally provided to collect spacer particles as in the present invention. The structure below the uneven surface is not important. Therefore, the step here refers to a step between a concave portion or a convex portion and a flat portion (reference surface) in the surface uneven shape.

Specifically, for example, in an array substrate in a TFT liquid crystal panel, a step (about 0.2 μm) due to a gate electrode or a source electrode as shown in FIGS. 3A to 3C, FIG. ), A step (about 1.0 μm) due to the array as shown in FIG. Further, in the color filter substrate, there is a recess step (about 1.0 μm) between the image color filters on the black matrix as shown in FIGS. 3D to 3F and 3H. .

In the present invention, when the spacer particle diameter is D (μm) and the step is B (μm), the step is preferably a step having a relationship of 0.01 μm <| B | <0.95D. If it is smaller than 0.01 μm, it may be difficult to collect spacer particles around the step, and if it exceeds 0.95 D, it may be difficult to obtain a substrate gap adjusting effect by the spacer particles.

As for the effect of the step, if there is a step, the droplet drying center is artificially fixed to the step portion at the final stage of drying. It is explained that the images can be collected at a very limited position around the step in the region corresponding to the non-pixel region.

In this case, as shown in FIG. 4, the position where the spacer particles 31 finally remain after drying is often a corner if it is a convex portion and is in a recess if it is a concave portion.

Regarding the effect of the step, if there is a metal in the vicinity of a step portion such as a wiring or a thin film such as an alignment film and the spacer particles are surface-modified or contain a charge control agent, Electrical interaction It is also considered that particles are moved and adsorbed by the so-called electrostatic “electrophoresis” effect. In this case, the metal species or the functional group of the compound used for the surface treatment such as wiring is changed by using, for example, an ionic functional group, or the charge control agent is added while adjusting the type, or A positive or negative voltage is applied to the wiring such as the source wiring and the gate wiring and the entire surface of the substrate so as not to damage the circuit. In this way, the crowding of the spacer particles can be controlled.

In the present invention, the spacer particle dispersion is discharged to a position including the position corresponding to the non-pixel region of the substrate described above using an ink jet apparatus.

In the present invention, it is preferable that the spacer particle dispersion is discharged to the substrate at intervals of the following formula (1) or more. This interval is the minimum interval between droplets when the next droplet is ejected while the landed spacer particle dispersion droplet is not dried.

In the above formula (1), D represents the particle diameter (μm) of the spacer particles, and θ represents the initial contact angle between the spacer particle dispersion and the substrate surface.

If the droplets are ejected at an interval smaller than the above formula (1), the droplet diameter remains large, the landing diameter also increases and droplet coalescence occurs, and the aggregation direction of the spacer particles occurs toward one place during the drying process. Disappear. As a result, there arises a problem that the arrangement accuracy of the spacer particles after drying is deteriorated. Further, if the nozzle diameter is reduced in order to reduce the amount of ejected droplets, the spacer particle diameter becomes relatively larger than the nozzle diameter. Therefore, as described above, the ink jet head nozzle is more stable, for example, always linear in the same direction. In particular, the spacer particles cannot be discharged, and the landing position accuracy decreases due to the flight bend. Further, the nozzle may be blocked by the spacer particles.

It is preferable that the arrangement number (dispersion density) of the spacer particles discharged and arranged on the substrate as in the above formula (1) is usually 50 to 350 / mm ² . Any pattern may be arranged in any part of the region corresponding to the non-pixel region such as black matrix or the non-pixel region such as wiring as long as the particle density is satisfied. However, in order to prevent protrusion to the display portion (pixel region), for a color filter composed of a lattice-shaped light-shielding region (non-pixel region), the lattice point of the lattice-shaped light-shielding region on one substrate It is more preferable to arrange for the corresponding part.

The number of spacer particles at one arrangement position is different for each arrangement position, but is generally about 0 to 12, and the average number is about 2 to 6. The average number is adjusted by the particle diameter of the spacer particles and the concentration of the spacer particle dispersion.

As described above, as a method of adjusting the spray density, for example, a method of changing the concentration of spacer particles in the spacer particle dispersion, a method of changing the discharge interval of the spacer particle dispersion, or the amount of droplets discharged at one time. The method of changing is mentioned.

Examples of a method for changing the amount of droplets landed on one location include a method for adjusting a waveform such as a voltage of an inkjet head, and a method for ejecting droplets multiple times at one location.

When changing the spray density by a method of changing the concentration of the spacer particles in the spacer particle dispersion, the type of spacer particles contained in the spacer dispersion can be changed. Therefore, various physical properties such as particle diameter hardness and recovery rate of the spacer particles to be used can be changed for each specific range of the substrate.

Regarding the dispersion density of the spacer particles, the standard deviation of the dispersion density of the spacer particles per mm ² is within 40% of the average value of the dispersion density within the specific range within a specific range on the substrate. Is preferred. When using the ink jet apparatus as described above, the normal state, i.e., the occurrence of non-ejection nozzles due to the variation in density due to the sedimentation of spacer particles, the clogging of the nozzles, and the remaining bubbles in the nozzles does not occur. If the discharge state is correct, the standard deviation can be easily within the above range. If the standard deviation is larger than 40% of the average value of the distribution density, the display state may be adversely affected due to a difference in cell gap between the substrates.

The number of spacer particles at one arrangement position is different for each arrangement position, but is generally about 0 to 12, and the average number is about 2 to 6. The average number is adjusted by the particle diameter of the spacer particles and the concentration of the spacer particle dispersion.

Further, in this way, in order to discharge the spacer particle dispersion and land the droplets on the substrate, the inkjet head can be scanned once or divided into a plurality of times. In particular, when the interval at which the spacer particles are to be arranged is narrower than the above formula (1), the particles are discharged at an integer multiple of the interval, dried once, shifted by that interval, and discharged again, etc. May be. With respect to the moving (scanning) direction as well, it can be alternately changed (reciprocating discharge) for each discharge and discharged only when moving in one direction (unidirectional discharge).

Further, as such an arrangement method, as disclosed in Japanese Patent Application No. 2000-19456, the head is inclined so as to have an angle with the perpendicular to the substrate surface, and the droplet discharge direction is changed (usually parallel to the perpendicular to the substrate surface). ) Further, the relative speed between the head and the substrate is controlled. In this way, it is possible to reduce the diameter of the droplets that land and make it easier to place the spacer particles in a region that further defines the pixel region or a region corresponding thereto.

(Method for drying spacer particle dispersion)
Next, after the droplets of the spacer particle dispersion liquid have landed on the substrate, the step of drying the medium (solvent, solvent) in the droplets and arranging the spacer particles at positions corresponding to the non-pixel regions will be described. .

The method of drying the spacer particle dispersion is not particularly limited, and examples thereof include a method of heating the substrate, blowing hot air or cold air, and drying under reduced pressure. However, in order to gather the spacer particles near the center of the landing droplet during the drying process, the boiling point of the medium, the drying temperature, the drying time, the surface tension of the medium, the contact angle of the medium with the alignment film, the concentration of the spacer particles, etc. It is preferable to set an appropriate condition.

In order to gather the spacer particles in the landing droplets during the drying process, the spacer particles are dried with a certain time width so that the liquid does not run out while the spacer particles move on the substrate. For this reason, the conditions under which the medium dries rapidly are not preferable. Further, when the medium comes into contact with the alignment film at a high temperature, the alignment film may be contaminated and the display image quality of the liquid crystal display device may be impaired. Accordingly, the substrate surface temperature until the drying is completed is preferably 90 ° C. or less, more preferably 60 ° C. or less. If the substrate temperature until the drying is completed exceeds 90 ° C., it is not preferable because the alignment film is damaged and the display image quality of the liquid crystal display device is impaired.

If the medium is extremely volatile at room temperature, or if the medium is used under conditions where it is violently volatile, the spacer particle dispersion near the nozzles of the ink jet device tends to dry out, and ink jetting properties are impaired. Further, aggregated particles may be generated during the production of the dispersion or by drying in a tank, which is not preferable.

Even if the substrate temperature is relatively low, if the drying time becomes extremely long, not only the production efficiency of the liquid crystal display device is lowered, but also the alignment film is contaminated or damaged due to the ink medium contacting the alignment film for a long time. Since it occurs, it is not preferable.

In the present invention, the substrate surface temperature when the spacer particle dispersion has landed on the substrate is preferably 20 ° C. or more lower than the boiling point of the lowest boiling solvent contained in the dispersion. More preferably, it is near room temperature (15-35 degreeC). When the temperature is higher than the boiling point of the lowest boiling point solvent by 20 ° C., the lowest boiling point solvent evaporates rapidly and the spacer particles cannot move. And the arrangement accuracy of the spacer particles is remarkably lowered.

Further, when the medium is dried while the substrate temperature is gradually increased after the spacer particle dispersion has landed on the substrate, the substrate surface temperature until the drying is completed is preferably 90 ° C. or less, and more preferably. Is 70 ° C. or lower. When the substrate temperature until the drying is completed exceeds 90 ° C., the alignment film is contaminated and the display image quality of the liquid crystal display device is deteriorated.

As described above, as a drying method for preventing the alignment film from being damaged, it is preferable to dry it at a temperature as low as possible in a short time. Specifically, it is preferable that the surface temperature of the substrate is set to 60 ° C. or less, and the droplets are dried within 5 seconds to 4 minutes (more preferably within 5 seconds to 2 minutes) after the droplets contact. . If the drying is performed in an excessively short time, the gathering of the spacer particles is deteriorated as described above, and the alignment film is damaged when the drying is performed for a long time.
Means for achieving this is to quickly remove the medium vapor in the vicinity of the droplets, that is, to apply wind or to dry under reduced pressure. However, if the air flow is too strong, the particles move around in the droplets, and as a result, the gathering of the spacer particles is hindered. Therefore, it is necessary to adjust the air flow appropriately.
However, depending on the type of the alignment film, it may be dried in a short time at a high temperature exceeding 90 ° C. in order to improve the gathering of the spacer particles. Specifically, it is preferable to perform drying at 100 to 150 ° C. for about 5 to 20 seconds.

In the present invention, the term “drying completion” refers to the time when the droplets on the substrate disappear.

Thereafter, the substrate may be heated to a higher temperature of about 120 to 230 ° C. in order to enhance the adhesion of the spacer particles to the substrate or remove the residual solvent.

(Step of superposing the first substrate and the second substrate so as to face each other through the liquid crystal and the spacer particles)
The substrate on which the spacer particles are arranged according to the manufacturing method of the present invention is thermocompression-bonded using a substrate on which the spacer particles are not arranged and a peripheral sealant, and a liquid crystal is filled in a gap between the formed substrates to form a liquid crystal display device. Fabricated (vacuum injection method). Alternatively, a peripheral sealing agent is applied to one substrate, a liquid crystal is dropped within a range surrounded by the other substrate, the other substrate is bonded, and the sealing agent is cured to prepare a liquid crystal display device (liquid crystal adversary method). In this case, spacer particles may be disposed on any substrate.

In the manufacturing method of the present invention, before and after disposing the liquid crystal, the volume resistance change rate of the liquid crystal is 1% or more, and the change in nematic / isotropic phase transition temperature of the liquid crystal is within ± 1 ° C. Yes.

When the volume resistivity change rate of the liquid crystal is 1% or more, the liquid crystal display device is excellent in display quality such as contrast and color tone. If the volume resistivity change rate of the liquid crystal is less than 1%, the liquid crystal is contaminated by the inclusion of conductive foreign substances present in the spacer particle dispersion liquid, and the display quality of the liquid crystal display device decreases, and afterimages and Display unevenness occurs. More preferably, the volume resistivity change rate of the liquid crystal is 10% or more. When the volume resistivity change rate of the liquid crystal is 10% or more, the display quality of the liquid crystal display device is further improved.

When the change in nematic / isotropic phase transition temperature of the liquid crystal is within ± 1 ° C., the display quality such as contrast and color tone of the liquid crystal display device is excellent. If the change in the nematic / isotropic phase transition temperature of the liquid crystal is outside the range of ± 1 ° C, impurities such as organic substances present in the dispersion of spacer particles are compatible with the liquid crystal and the liquid crystal is contaminated. The display quality of the apparatus deteriorates, and afterimages and display unevenness occur.

Thus, the voltage holding ratio of the liquid crystal display device configured according to the manufacturing method of the present invention is 90% or more. When a liquid crystal display device is manufactured regardless of the manufacturing method of the present invention, the voltage holding ratio is often less than 90%. When the voltage holding ratio is less than 90%, the voltage is lowered within one driving time of the pixel, the display quality of the liquid crystal display device is lowered, and an afterimage or display unevenness may occur.

Thus, the residual DC voltage of the liquid crystal display device configured according to the manufacturing method of the present invention is 200 mV or less. When a liquid crystal display device is manufactured regardless of the manufacturing method of the present invention, the residual DC voltage often exceeds 200 mV. When the residual DC voltage exceeds 200 mV, the voltage may remain in the pixel even after the voltage application is stopped, and the display quality deteriorates due to the occurrence of afterimages and display unevenness. The residual DC voltage is an index of contamination of the liquid crystal and the alignment film.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

[Examples and Comparative Examples]
(Preparation of spacer particles)
In a separable flask, 15 parts by weight of divinylbenzene, 5 parts by weight of isooctyl acrylate, and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were uniformly mixed. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (trade name “Kuraray Poval GL-03”, manufactured by Kuraray Co., Ltd.) and 0.5 parts by weight of sodium dodecyl sulfate were added and stirred well. Thereafter, 140 parts by weight of ion-exchanged water was added. The solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. The obtained particles were washed with hot water and acetone and then classified to obtain spacer particles having an average particle size of 3.0 μm, 4.0 μm and 5.0 μm, and a CV value of 3.0%.

(Surface modification of spacer particles)
5 parts by weight of spacer particles having an average particle diameter of 3.0 μm, 4.0 μm and 5.0 μm and a CV value of 3.0% were obtained, 20 parts by weight of dimethyl sulfoxide (DMSO), and 2 parts by weight of hydroxymethyl methacrylate And 18 parts by weight of N-ethylacrylamide, and uniformly dispersed by a sonicator. Thereafter, nitrogen gas was introduced into the reaction system and stirring was continued at 30 ° C. for 2 hours. Next, 10 parts by weight of a 0.1 mol / L ceric ammonium nitrate solution prepared with a 1N nitric acid aqueous solution was added, and the reaction was continued for 5 hours. After completion of the reaction, the particles and the reaction solution were separated by filtration with a 2 μm membrane filter. The particles were sufficiently washed with ethanol and acetone, and dried under reduced pressure in a vacuum dryer to obtain spacer particles SA.

5 parts by weight of spacer particles having an average particle diameter of 4.0 μm and a CV value of 3.0% obtained by the preparation of the spacer particles, 20 parts by weight of dimethyl sulfoxide (DMSO), 2 parts by weight of hydroxymethyl methacrylate, The solution was charged into 16 parts by weight of methacrylic acid and 2 parts by weight of lauryl acrylate, and uniformly dispersed by a sonicator. Thereafter, spacer particles SB were obtained in the same manner as the spacer particles SA.

5 parts by weight of spacer particles having an average particle diameter of 4.0 μm and a CV value of 3.0% obtained by the preparation of the spacer particles, 20 parts by weight of dimethyl sulfoxide (DMSO), 2 parts by weight of hydroxymethyl methacrylate, The solution was put into 18 parts by weight of polyethylene glycol methacrylate (molecular weight 800) and uniformly dispersed by a sonicator. Thereafter, spacer particles SC were obtained in the same manner as the spacer particles SA.

10 parts by weight of spacer particles having an average particle diameter of 4.0 μm and a CV value of 3.0% obtained by the preparation of the spacer particles, 20 parts by weight of methyl ethyl ketone, and 3 parts by weight of a 30% toluene solution of methacryloyl isocyanate The mixture was allowed to react at 100 to 150 ° C. for 1 to 2 hours to introduce vinyl groups on the surface of the spacer particles. Thereafter, spacer particles whose surface was modified with vinyl groups were obtained by centrifugation. 10 parts by weight of the spacer particles introduced with the vinyl group were put into 1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts by weight of methyl cellosolve. Next, the temperature was raised to 60 ° C., which is the initiator cleavage temperature, and reacted for 2 hours under a nitrogen stream to generate radicals on the vinyl groups on the particle surface. Thereafter, 5 parts by weight of hydroxymethyl methacrylate, which is a polymerized vinyl monomer having an OH group and capable of dissolving the homopolymer in methyl cellosolve, and 45 parts by weight of polyethylene glycol methacrylate (molecular weight 800) are dropped and reacted for 1 hour. Thus, spacer particles having an adhesion layer composed of graft polymerization chains on the surface were obtained. After completion of the reaction, the spacer particles and the reaction solution were separated by filtration with a 2 μm membrane filter. The spacer particles were thoroughly washed with ethanol and acetone, and dried under reduced pressure in a vacuum dryer to obtain spacer particles SD that were surface-modified by graft polymerization.

(Preparation of spacer particle dispersion)
All the solvents used for preparing the spacer dispersion were grades for the electronics industry. The spacer particle dispersion was prepared in a clean room (Class 10000).

Disperse the spacer particles obtained by the above-mentioned method by taking a necessary amount so as to have a predetermined particle concentration, slowly adding to the solvent having the composition described in Tables 1 and 2 below, and stirring sufficiently while using a sonicator. I let you. Thereafter, the mixture was filtered through a stainless steel mesh having an opening of 10 μm to remove aggregates, thereby obtaining a spacer particle dispersion.

Next, in Examples 1 to 10 shown in Table 1 below, the spacer particle dispersion was filtered with a filter having a filtration diameter through which the spacer particles can pass. Next, a centrifugal sedimentation operation was performed to remove dust particles and dust substances, which are non-volatile components, and then the supernatant was discarded. This was dispersed in a solvent having the composition described in Table 1 below, which was filtered through a filter having a diameter of 0.1 μm. This operation was performed again. The obtained spacer particle dispersions S1 to S10 from which the non-volatile components were removed were placed in a borosilicate glass container.

On the other hand, in the spacer particle dispersion liquid of Comparative Example 1 shown in Table 2 below, the same operation as that performed in Examples 1 to 10 was performed. The obtained spacer particle dispersion S11 from which the non-volatile components were removed was placed in an alkali (soda) glass container.

On the other hand, in the spacer particle dispersion liquids of Comparative Examples 2 to 6 shown in Table 2 below, the operations performed in Examples 1 to 10 were not performed, and the nonvolatile components were not removed. The obtained spacer particle dispersions S12 to S16 were put in a borosilicate glass container.

The surface tension of the obtained spacer particle dispersions S1 to S16 was measured by the Wilhelmy method using a platinum plate. The measurement results of surface tension, viscosity, specific gravity and sedimentation rate are shown in Tables 1 and 2 below.

(Production of substrate)
A liquid crystal display device substrate (TFT array model substrate) simulating a step in the TFT array substrate was used as the first substrate for the liquid crystal test panel, and a color filter substrate was used as the second substrate.

(Color filter substrate)
The color filter substrates used in Examples and Comparative Examples are shown in a plan view in FIG. 5A and a front sectional view in FIG. The color filter substrate 41 having a smooth surface was produced as follows.
As shown in FIGS. 5A and 5B, a black matrix 43 (width 25 μm, vertical interval 150 μm, horizontal interval 75 μm, thickness 0. 2 μm). Color filter 44 pixels (thickness 1.5 μm) composed of three colors of red, green and blue were formed on and between the black matrix 43 so as to have a flat surface. An overcoat layer 45 and an ITO transparent electrode 46 having a substantially constant thickness were provided thereon.

Furthermore, a polyimide resin solution (manufactured by Nissan Chemical Industries, Ltd., Sunever SE1211) was uniformly applied thereon by a spin coat method. After coating, the film was dried at 80 ° C., then baked at 190 ° C. for 1 hour, and cured to form an alignment film (PI2) 47 having a substantially constant thickness. The formed alignment film (PI2) 47 had a surface tension (γ) of 39 mN / m.

(TFT array model substrate)
The TFT array model substrate provided with the steps shown in the plan view in FIG. 6A and in the front view in FIG. 6B was produced as follows.

As shown in FIGS. 6A and 6B, the TFT array model substrate 51 is formed on the glass substrate 52 at a position facing the black matrix 43 of the color filter substrate 41 by a conventionally known method. A step 53 (width 8 μm, height difference 5 nm) made of copper was provided. An ITO transparent electrode 54 having a substantially constant thickness was provided thereon, and an alignment film 55 having a substantially constant thickness was formed by the method described above. In the TFT array model substrate 51, the alignment film 55 was formed using the same polyimide resin solution as that of the counter substrate.

(Inkjet device)
An inkjet apparatus equipped with a piezo-type head having a diameter of 50 μm was prepared. The liquid contact part of the ink chamber of this head was made of a glass ceramic material. The nozzle surface was subjected to fluorine-based water repellent finish.

(Spacer particle arrangement by inkjet method)
Spacer particles were arranged on the TFT array model substrate 51 by the following method using the spacer particle dispersions S1 to S9 shown in Tables 1 and 2 below. In addition, when arrange | positioning spacer particle | grains, arrangement | positioning was started after throwing away 0.5 mL of the initial spacer particle dispersion liquid discharged from the nozzle of an inkjet apparatus.

First, the TFT array model substrate 51 having the step 53 shown in FIG. 6 was placed on a stage heated to 45 ° C. with a heater. On this substrate, using the above-described ink jet device, aiming at the step 53 corresponding to the black matrix 43, the spacers shown in Table 1 are arranged at intervals of 110 μm on every other vertical line and on the vertical line. The droplets of the particle dispersion were discharged at a pitch of 110 μm in length and 150 μm in width and placed and dried. The distance between the nozzle tip and the substrate during ejection was 0.5 mm, and ejection was performed by the double pulse method.

After ejection, the initial contact angle (θ) and receding contact angle (θr) of the droplets of the spacer particle dispersion with respect to the substrate were measured with a contact angle meter. The results are shown in Tables 1 and 2.

(Production of liquid crystal display device for evaluation)
The TFT array model substrate 51 on which the spacer particles are arranged as described above and the color filter substrate 41 serving as the counter substrate are bonded together using a peripheral sealant. After the bonding, the sealing agent is heated at 150 ° C. for 1 hour to be cured to produce an empty cell in which the cell gap is equal to the particle diameter of the spacer particles, and then the liquid crystal is filled by a vacuum method. Then, the inlet was sealed to prepare a liquid crystal display device.

(Evaluation of Examples 1 to 10 and Comparative Examples 1 to 6)
The following items were evaluated. The results are shown in Tables 1 and 2.

(Change rate of volume resistance of liquid crystal)
Each of the spacer particle dispersions 0.5 g of S1 to S16 was put into a sample bottle, and dried at 90 ° C. for 5 hours under vacuum to dryness. After that, in the sample bottle, liquid crystal (chisso Li
xon JC5007XX) 0.5 g was added and allowed to stand at room temperature for 12 hours.

Thereafter, the volume resistance value was measured under the conditions of 5 V and 25 ° C. using a Toyo Technica Corporation specific resistance measuring device, and the volume resistance change rate was calculated according to the following formula (2).
Volume resistance change rate = Volume resistance value of liquid crystal after test / Volume resistance value of liquid crystal before test) × 100 (%) (2)

(Change of nematic and isotropic phase transition temperature of liquid crystal)
0.5 g of the spacer particle dispersion obtained by preparing the spacer particle dispersion described above was put in a sample bottle and dried in a vacuum at 90 ° C. for 5 hours to dry. Thereafter, 0.5 g of liquid crystal (chisso Lixon JC5007XX) was placed in the sample bottle and allowed to stand at room temperature for 12 hours.

Thereafter, using a DSC apparatus, the nematic / isotropic phase transition temperature is measured by scanning at a rate of 10 ° C./min in the range of 0 to 110 ° C., and the nematic / isotropic phase transition is measured according to the following formula (3). The change in temperature was calculated.
Change in nematic / isotropic phase transition temperature of liquid crystal = nematic / isotropic phase transition temperature before test−nematic / isotropic phase transition temperature of liquid crystal after test (3)

(Non-volatile content)
200 g of the S1-S16 spacer particle dispersion was centrifuged at 2500 rpm for 3 minutes to precipitate most of the spacer particles, and then the first supernatant was collected. Thereafter, the solvent composition of the spacer particle dispersion liquid described in Tables 1 and 2 below was added to the precipitated spacer particles and sufficiently dispersed by ultrasonic waves. Next, the same operation as described above was performed again, and a second supernatant was collected. Thereafter, the second supernatant was added to the first supernatant.

Next, the 1st and 2nd supernatant liquids were filtered using the filter which consists of a fluororesin which has a 1 micrometer filtration diameter smaller than spacer particle | grains. Thereafter, the supernatant liquid passed without being captured by the filter made of a fluororesin having a filtration diameter of 1 μm was dried. After drying, the weight of the dried product was measured, and the content ratio of the non-volatile components present in 100% by weight of the S1-S16 spacer particle dispersion was calculated.

When observing the presence of non-volatile components, small particles that are thought to be related to dust in the atmosphere, those in which the surface of the spacer particles is peeled off, those in which the spacer particles are destroyed, and the above-described surface modification of the spacer particles An amorphous solid that appears to be a homopolymer, monomer, or oligomer was observed in the treatment.

(Spacer particle dispersion density)
After the spacer particles were fixed to the substrate, the number of spacer particles dispersed per 1 mm ² was observed to obtain the distribution density.

(Average number of spacer particles)
An average value of the number of spacer particles aggregated per one arrangement position was measured within the range of 1 mm ² . In Table 1, “-” indicates that measurement is not possible because no aggregation occurs.

(Spacer particle placement accuracy)
The arrangement state of the spacer particles after the droplets were dried was determined according to the following criteria.

○: Almost all spacer particles were at positions corresponding to the non-pixel areas (light-shielding areas).
(Triangle | delta): It existed in the position which one part spacer particle protruded from the position (light-shielding area | region) corresponding to a non-pixel area | region.
X: Many spacer particles were in a position protruding from the position corresponding to the non-pixel area (light shielding area).

(Spacer particle existence range)
As shown in FIG. 7, parallel lines are drawn at equal intervals on both sides from the center of the black matrix or the corresponding portion, and 95% or more spacer particles are present between the two parallel lines. The distance between the existing parallel lines was defined as the spacer particle existence range.

(Display quality)
(1) Evaluation of exposure to light The display image quality of the liquid crystal display device was observed and judged according to the following criteria.

A: Almost no spacer particles were observed in the display area, and no light leakage due to the spacer particles was observed.
Δ: Some spacer particles were observed in the display area, and light leakage due to the spacer particles was observed.
X: Spacer particles were observed and light leakage due to the spacer particles was observed.

(2) Voltage holding ratio and (3) Residual DC voltage A 50 mm × 50 mm substrate patterned with an ITO transparent electrode was prepared. An alignment film was formed on the substrate using a polyimide solution (NISSAN CHEMICAL SUNEVER SE7942).

Thereafter, according to the above process, spacer particles were arranged using an ink jet apparatus. Next, the substrate on which the spacer particles were arranged was bonded to the substrate on which the other spacer particles were not arranged with a sealant (MITSHI CHRMICALS STRACTBOND XN-21-S) and cured. Next, liquid crystal (CHISSO LIXON JC5007) was injected under vacuum to produce an evaluation cell.

The voltage holding ratio and residual DC voltage of the produced evaluation cell were measured under the following conditions using a liquid crystal property measuring system 6254 (manufactured by Toyo Technica Co., Ltd.).

VHR: 60μs 5V-16.61msec voltage measured after holding (ratio)
RDC: measurement of voltage between substrates after application of 1 hr 5 V-1 sec short-10 minutes In the evaluation of the voltage holding ratio and residual DC voltage, if the voltage holding ratio is less than 90% in the manufactured TFT array model, the actual liquid crystal When the panel is manufactured, there may be a problem that the liquid crystal driving voltage of the panel changes.

Further, if the residual DC voltage exceeds 200 mV in the TFT array model, an afterimage may occur on the panel when an actual liquid crystal panel is manufactured.

  Table 3 below shows the boiling points, viscosities, and surface tensions of the solvents used in the examples and comparative examples.

  As is clear from Table 1, the liquid crystal display device of the example was excellent in display image quality.

1 is a front cross-sectional view schematically showing a liquid crystal display device obtained by a method for manufacturing a liquid crystal display device according to an embodiment of the present invention. It is a schematic diagram showing the droplet discharge state from an inkjet nozzle, (a) shows the case where a meniscus is not an axis object, and (b) shows the case where a meniscus is an axis object. (A)-(h) is a schematic diagram showing the example of the level | step-difference part provided in the surface of the board | substrate. The schematic diagram showing the position where spacer particle | grains remain. (A), (b) is the top view and front sectional drawing which show typically the color filter board | substrate used by an Example and a comparative example. (A), (b) is the top view and front view which show typically the TFT array model board | substrate used by an Example and a comparative example. The schematic diagram which shows the evaluation method of the existence range of spacer particle | grains. (A), (b) is the partial notch perspective view which shows typically the structure of an example of an inkjet head, and the partial notch perspective view which shows the cross section in a nozzle hole part. Front sectional drawing which shows the conventional liquid crystal display device typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device 2 ... 1st board | substrate 3 ... 2nd board | substrate 4 ... Color filter 5 ... Black matrix 6 ... Overcoat layer 7 ... Transparent electrode 8 ... Alignment film 9 ... Transparent electrode 10 ... Alignment film 11, 12 ... Deflection plate 13 ... Sealing material 14 ... Spacer particle 15 ... Liquid crystal 21 ... Spacer particle 22 ... Meniscus 23 ... Spacer particle dispersion 31 ... Spacer particle 41 ... Color filter substrate 42 ... Crow substrate 43 ... Black matrix 44 ... Color filter 45 ... Over Coat layer 46 ... Transparent electrode 47 ... Alignment film 51 ... TFT array model substrate 52 ... Glass substrate 53 ... Step 54 ... Transparent electrode 55 ... Alignment film 100 ... Head 101 ... Ink chamber 1 (common ink chamber)
102: Ink chamber 2 (pressure ink chamber)
103 ... discharge surface (nozzle surface)
104 ... Nozzle hole 105 ... Temperature control means 106 ... Piezo element

Claims (4)

A method of manufacturing a liquid crystal display device having a pixel region and a non-pixel region,
By ejecting a spacer particle dispersion liquid in which spacer particles are dispersed in a medium using an ink jet apparatus on the surface of the first substrate or the second substrate, a specific position corresponding to the non-pixel region is obtained. Arranging the spacer particles;
Stacking the first substrate and the second substrate so as to face each other with the liquid crystal and the spacer particles interposed therebetween,
In the step of superposing the liquid crystal and the spacer particles so as to face each other, the volume resistivity change rate of the liquid crystal is 1% or more before and after the liquid crystal is disposed, and the nematic / isotropic phase transition temperature of the liquid crystal The method of manufacturing a liquid crystal display device, characterized in that the change in temperature is within ± 1 ° C. A spacer particle dispersion used in the method for producing a liquid crystal display device according to claim 1. A spacer particle dispersion used when spacer particles are arranged on the surface of a substrate using an ink jet apparatus, which contains at least spacer particles and a medium, and the spacer particles are surface-modified by graft polymerization. A spacer particle dispersion having a nonvolatile component content of less than 0.001% by weight. A liquid crystal display device comprising the liquid crystal display device manufacturing method according to claim 1 or the spacer dispersion liquid according to claim 2 or 3.

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