JP2007310414A - Spacer dispersion liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spacer dispersion liquid capable of accurately arranging spacers on a non-display part of a liquid crystal display device substrate and manufacturing a liquid crystal display device having such a high display quality as to permit prevention of light leakage and light escaping due to spacers. <P>SOLUTION: The spacer dispersion liquid used in a manufacturing method of the liquid crystal display device in which the spacers are arranged on arbitrary positions on the substrate according to an inkjet method comprises at least the spacers and a medium and contains a liquid having a boiling point of <100°C by 10 to 80 wt.% as the medium, wherein a spacer content is 0.05 to 5 wt.% and the viscosity in a temperature range of -5 to 50°C falls into the range of 0.5 to 15 mPa s. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention provides a spacer dispersion liquid in which a spacer can be accurately placed on a non-display portion of a liquid crystal display device substrate, and a liquid crystal display device having high display quality that prevents light leakage and light leakage by the spacer can be manufactured. About.

Liquid crystal display devices are currently widely used in personal computers, portable electronic devices, and the like. In general, as shown in FIG. 1, the liquid crystal display device includes a transparent electrode 3, an alignment film 9, a color filter 4, a black matrix 5, and the like formed inside two transparent substrates 1. The polarizing plate 2 is disposed outside the substrate, the sealing material 10 is disposed around the two transparent substrates 1, and the liquid crystal 7 is sealed in the gap between the two transparent substrates 1 disposed so as to face each other through the sealing material 10. Has been configured. In this liquid crystal display device, a spacer 8 is used for the purpose of regulating the distance between the two transparent substrates 1 and maintaining an appropriate liquid crystal layer thickness (cell gap).

In the conventional method for manufacturing a liquid crystal display device, spacers are randomly and uniformly distributed on the substrate on which the pixel electrodes are formed. Therefore, as shown in FIG. It was sometimes done. The spacer is usually made of synthetic resin, glass or the like, and when the spacer is arranged on the pixel electrode, the portion where the spacer is arranged causes light leakage due to the biasing action. Further, when the alignment of the liquid crystal is disturbed on the surface of the spacer, light leakage occurs, and the contrast and color tone are lowered to deteriorate the display quality. Further, in the TFT liquid crystal display device, when the spacer is disposed on the TFT element on the substrate, there is a serious problem that the element is damaged when pressure is applied to the substrate.

In order to solve the problem associated with the random dispersion of the spacers, it has been proposed to arrange the spacers only in the light-shielding region that is a non-display portion of the liquid crystal display device. As a method of arranging the spacer only at a specific position as described above, for example, in Patent Document 1, a mask having an opening corresponds to the opening after combining the opening and the position where the opening is desired to be arranged. A method of disposing only at a position is disclosed, and Patent Document 2 discloses a method of electrostatically attracting a spacer to a photosensitive member and then transferring it to a transparent substrate. However, in these methods, since a mask or a photoreceptor is brought into direct contact with the substrate, there is a problem in that the image quality of the liquid crystal display is deteriorated by damaging the alignment film on the substrate.

On the other hand, Patent Document 3 proposes a method in which a voltage is applied to pixel electrodes on a substrate, and charged resin spacers are dispersed to dispose them at specific positions by electrostatic repulsion. However, since this method requires electrodes according to the pattern to be arranged, it cannot be completely arranged at any position, and may not be applicable to the production of a specific type of liquid crystal display device. It was.

On the other hand, Patent Document 4 discloses a method of arranging spacers by an ink jet method. This method can be said to be an effective method in that the spacer can be arranged in an arbitrary pattern at an arbitrary position without bringing a mask or the like into contact with the substrate as in the above-described method.

However, in the conventional ink jet method, the droplets that have landed on the substrate spread in a circular shape, or even if the ejected droplets are separated into a plurality of droplets, the droplets land on the same location, so the droplets are superimposed again and become large. There is a problem that the size (landing diameter) of the landed droplet becomes a droplet and cannot be controlled to be equal to or smaller than the size of a light shielding region called a black matrix on the substrate suitable for arranging the spacer. In particular, in an inkjet printer for printing, there is a problem that the resolution of an image may be lowered if the landing position of a discharged droplet is slightly shifted.
While the width of the black matrix is usually 10 to 30 μm, the landing diameter of droplets ejected from the ink jet apparatus in the ink jet method is generally about 40 to 200 μm, and it is necessary to reduce the landing diameter. .

As a method of reducing the landing diameter, for example, a method of reducing the nozzle diameter of the ink jet apparatus is conceivable, but the diameter of the nozzle of the current ink jet apparatus is about 20 μm at the minimum, and the particles of the spacer for the liquid crystal display device Since the diameter is generally 2 to 10 μm, it is difficult to further reduce the nozzle diameter of the ink jet apparatus because the nozzle is blocked and the ejection becomes unstable.
As described above, it is extremely difficult to arrange the spacers in the non-display portion of the liquid crystal display device by the conventional ink jet method in view of the size of the droplets discharged from the ink jet device.
Japanese Patent Laid-Open No. 4-198919 JP-A-6-258647 JP-A-10-339878 JP-A-57-58124

In view of the above-described present situation, the present invention can manufacture a liquid crystal display device having high display quality in which spacers can be accurately arranged in a non-display portion of a liquid crystal display device substrate and light leakage and light leakage by the spacers are prevented. An object of the present invention is to provide a spacer dispersion that can be used.

The present invention is a spacer dispersion used in a method for manufacturing a liquid crystal display device in which spacers are arranged at arbitrary positions on a substrate by an ink jet method, and contains at least a spacer and a medium, and has a boiling point of 100 as the medium. A spacer dispersion containing 10 to 80% by weight of a liquid having a temperature of less than 0 ° C., a spacer content of 0.05 to 5% by weight, and a viscosity in the temperature range of −5 to 50 ° C. of 0.5 to 15 mPa · s. is there.
The present invention is described in detail below.

In the method for manufacturing a liquid crystal display device using the spacer dispersion liquid of the present invention, the spacers are arranged on the substrate by discharging droplets of the spacer dispersion liquid of the present invention from the nozzles of the ink jet apparatus and landing on the substrate. And a step of disposing the spacer on the substrate, the relative velocity V ₁ (m / s) between the nozzle and the substrate, and the tip of the droplet of the spacer dispersion liquid starts to be discharged from the nozzle. The time t (s) required until the trailing edge of the spacer dispersion liquid droplet is completely discharged from the nozzle, the distance L (m) between the nozzle and the substrate, the surface of the substrate and the droplet of the spacer dispersion liquid The angle θ (degrees) formed with the discharge direction, the velocity V ₂ (m / s) of the leading edge of the spacer dispersion liquid droplet, and the velocity V ₃ (m / s) of the trailing edge of the spacer dispersion liquid are controlled. By The landing distance l which is obtained by the following formula (1) to greater than 40 [mu] m.

The method for manufacturing a liquid crystal display device includes a step of disposing spacers on a substrate by discharging droplets of the spacer dispersion liquid of the present invention from nozzles of an ink jet device and landing on the substrate.
The ink jet device is not particularly limited, and for example, a normal discharge method such as a piezo method that discharges liquid by vibration of a piezo element or a thermal method that discharges liquid by using rapid expansion of the liquid is used. An ink jet apparatus etc. are mentioned.

The preferable lower limit of the nozzle diameter of the ink jet apparatus is 20 μm, and the preferable upper limit is 100 μm. When the spacer is less than 20 μm, when a spacer having a particle diameter of 2 to 10 μm is discharged, the difference from the particle diameter is too small and the discharge accuracy is lowered or, in the case of remarkably, the nozzle is blocked and the discharge cannot be performed. is there. If it exceeds 100 μm, the droplets to be ejected become large and the landing diameter becomes large, so that the accuracy of arranging the spacers may be rough.
A plurality of nozzles of the ink jet apparatus are usually arranged on the head by an arrangement method in which the nozzles are arranged at equal intervals in a direction orthogonal to the moving direction of the head of the ink jet apparatus.

The preferable lower limit of the diameter of the droplets of the spacer dispersion discharged from the nozzle is 10 μm, and the upper limit is 80 μm. If it is less than 10 μm, the droplets become lighter, so that the landing position may be displaced by being disturbed by the air flow. If it exceeds 80 μm, the landing diameter becomes large, so it is necessary to land the droplets with very high accuracy. There is.
Examples of the method for controlling the diameter of the droplet include a method for optimizing the nozzle diameter and a method for optimizing an electric signal for controlling the ink jet head. The method of optimizing the electric signal for controlling the ink jet head is particularly effective when a piezo ink jet apparatus is used.

In the method for manufacturing the liquid crystal display device, the spacer is disposed on the substrate by discharging droplets of the spacer dispersion liquid from the nozzles of the ink jet device and landing on the substrate.
If the manufacturing method of the liquid crystal display device is used, the spacers on the substrate can be arranged randomly or arranged in a specific position, but the display image quality is deteriorated due to the spacer such as light leakage. In order to suppress it, it is preferable to arrange it in a non-display portion of the panel. The non-display portion includes a light blocking layer called a black matrix formed around the pixel and a portion where the TFT element is located in the TFT liquid crystal display device, but the TFT element is not destroyed. The spacer is preferably disposed under the black matrix. The width of the black matrix is usually 10 to 30 μm.

The number of spacers arranged is preferably 50 to 350 in a 1 mm square region. Any pattern may be arranged in any part of the black matrix as long as the particle density is satisfied. However, in order to prevent protrusion to the display part, a color filter composed of a lattice-shaped light shielding region is used. On the other hand, it is preferable to aim at a position corresponding to the lattice point of the lattice-shaped light shielding region on one substrate.

In order to enable such a spacer arrangement, in the liquid crystal display device manufacturing method, droplets are ejected while the nozzle and the substrate are moved relatively, and the position at which the tip of the droplet lands on the substrate. The distance between the positions where the trailing edge of the droplet landed (inter-landing distance l) is set to be larger than 40 μm.
By increasing the inter-landing distance l to more than 40 μm, in the conventional method for discharging the spacer dispersion liquid, the spacer dispersion liquid has landed on the substrate as one circular droplet, whereas the liquid crystal display device In this manufacturing method, the spacer dispersion liquid lands on the substrate as elliptical droplets or circular droplets divided into several small droplets.
When the ejected liquid droplets are divided and landed, the inter-drop distance between the first landed liquid droplet and the liquid droplet landed farthest is the inter-landing distance l.

FIG. 2 shows a schematic diagram of a landing state when droplets of spacer dispersion liquid are landed on a substrate by a conventional spacer dispersion liquid discharge method, and a method for manufacturing a liquid crystal display device using the spacer dispersion liquid of the present invention FIG. 3 is a schematic diagram showing an example of a landing state when droplets of the spacer dispersion liquid are landed on the substrate by the spacer dispersion liquid discharging method in FIG.
Compared to the landing diameter (D1) when the spacer dispersion liquid droplets are landed on the substrate by the conventional spacer dispersion liquid discharge method shown in FIG. 2, the spacer dispersion liquid of the present invention shown in FIG. 3 is used. Among the elliptical droplets having a short diameter (D2) or small droplets when the spacer dispersion liquid droplets land on the substrate by the spacer dispersion liquid discharge method in the manufacturing method of the liquid crystal display device. The maximum impact diameter (D3) is small and easily fits in the non-display portion of the panel.

The landing state is determined by the relative velocity V ₁ flight conditions and the substrate and the nozzle since the liquid droplets from the nozzle provided jumps out in the head. That is, the spacer dispersion liquid ejected by the ink jet method is ejected as a rod-like droplet from the nozzle, but the spacer dispersion liquid droplets are directly on the substrate without being split in the air as shown in FIG. Or split into two or more droplets in the air and land on the substrate as shown in FIG. At this time, when the relative velocity V ₁ of the nozzle and the substrate is very small, even any flight conditions, the lands near the same place on the substrate, becomes substantially circular. When the relative velocity V ₁ of the nozzle and the substrate is small, an elliptical shape be in any flight condition. When the relative velocity V ₁ is greater between the nozzle and the substrate, if not separated in the air, it becomes elliptical shape, when separating the air becomes circular or elliptical few drops which split small.

Although the details of the inter-landing distance l are omitted, it can be calculated by the above formula (1). Therefore, the relative velocity V ₁ (m / s) between the nozzle and the substrate, and the tip of the droplet of the spacer dispersion liquid is the nozzle. The time t (s) required from the start of discharge until the trailing edge of the droplet of the spacer dispersion liquid is completely discharged from the nozzle, the distance L (m) between the nozzle and the substrate, the surface of the substrate and the droplet of the spacer dispersion liquid By controlling the angle θ (degrees) made with the ejection direction, the velocity V ₂ (m / s) of the leading edge of the spacer dispersion liquid droplet, and the velocity V ₃ (m / s) of the trailing edge of the spacer dispersion liquid. The landing distance 1 can be made larger than 40 μm.

Next, each parameter of the above equation (1) will be described.
First, the distance between the droplet discharge port (nozzle tip) of the head and the substrate is L, and the head (nozzle) is tilted so that the angle between the substrate surface and the droplet discharge direction is θ, etc. Install. From the nozzle, the spacer dispersion liquid was discharged to the substrate moving so that the relative velocity between the head and the substrate was V ₁ so that the velocity of the droplet tip was V _2, and time t passed. Later, the trailing edge of the droplet finishes ejection. The speed of the droplet trailing end of this time is V _3. This is set as one cycle, and this is repeated to dispose spacer dispersion liquid droplets on the substrate.

From the above formula (1), in order to increase the landing distance 1, the relative velocity V ₁ between the nozzle and the substrate, the discharge time t, the distance L between the nozzle and the substrate, or the surface of the substrate and the spacer dispersion liquid are increased. The angle θ formed by the droplet discharge direction is made closer to the horizontal to reduce sin θ, or the velocity V ₂ at the leading edge of the spacer dispersion liquid and the velocity V _{3 at the} trailing edge of the spacer dispersion liquid are decreased, and, it may be or reduce the speed V ₃ of the droplet trailing end of the spacer dispersion with respect to the droplet tip speed V ₂ of the spacer dispersion.

The upper limit of the relative velocity V ₁ of the the above nozzle and the substrate is determined by the capability of the drive device such as an acceleration accuracy and positional accuracy of the drive unit at the moment is about 100 m / s.
By increasing the relative speed V ₁ of the the above nozzle and the substrate, when the discharge gap of the spacer dispersion (1 cycle time) is short, it can not be arranged spacers in the desired spacing, a plurality of times spacers This can be solved by landing the dispersion liquid or increasing the number of nozzles. The method for landing the spacer dispersion liquid in a plurality of times is not particularly limited. For example, the movement direction may be alternately changed every time (reciprocating discharge), or may be discharged only when moving in one direction. You may discharge (unidirectional discharge).

The ejection time t is set to 3 μs to 1 ms depending on the control condition of the voltage applied to the piezo element. The control condition of the voltage applied to the piezo element is set according to the waveform control condition, the surface tension, the viscosity, etc. of the spacer dispersion so that the spacer dispersion can be discharged stably.

The preferable lower limit of the distance L between the nozzle and the substrate is 200 μm, and the preferable upper limit is 3 mm. If it is less than 200 μm, the nozzle and the substrate may come into contact with each other due to unexpected vibration, and the substrate may be damaged or the nozzle may be damaged. If it exceeds 3 mm, the droplets of the spacer dispersion liquid are so small that they are easily affected by the airflow in the atmosphere, or the slight bending of the droplets is enlarged, so that it is easy to deviate from the expected landing position. Problems can occur. A more preferable lower limit is 300 μm, and a more preferable upper limit is 1.5 mm.

The preferable lower limit of the angle θ formed by the surface of the substrate and the discharge direction of the droplets of the spacer dispersion liquid is 5 degrees, and the preferable upper limit is 175 degrees. If the angle is less than 5 degrees or exceeds 175 degrees, the time during which the droplet stays in the air before landing is increased, and the spacer dispersion liquid is increased in the same manner as when the distance L between the nozzle and the substrate is increased. Since the droplets are small, they may be easily affected by the air flow in the atmosphere, or a slight bend of the main droplet may be enlarged, which may cause problems such as being easily displaced from the expected landing position.

The velocity V ₂ at the tip of the spacer dispersion liquid droplets can be generally controlled in the range of 3 to 20 m / s by increasing or decreasing the voltage applied to the piezo element in a piezo ink jet apparatus. A preferred lower limit of the droplet tip velocity _{V 2} of the spacer dispersion 5 m / s, preferably the upper limit is 12m / s.
Velocity V ₃ of the droplet trailing end of the spacer dispersion is smaller than the speed V ₂ of the droplet leading end of the spacer dispersion, it is generally 1 to 10 m / s. Velocity V ₃ of the droplet trailing end of the spacer dispersion, separation state of the droplets of the spacer dispersion, i.e., determined by the surface tension and viscosity of the spacer dispersion.

As described above, the liquid droplets are ejected in the form of a rod, and there are cases where the liquid droplets do not break up or break up before landing on the substrate. In the case where the droplet does not break up and becomes a spherical droplet in the air as shown in FIG. 4 before landing, the leading edge velocity and the trailing edge velocity at the landing are almost the same. Since the rod-shaped droplets become spherical, the droplet velocity at landing is strictly different from the droplet tip velocity and trailing edge velocity at ejection, but the difference is small relative to the droplet velocity, so here The same.
On the other hand, in the case of splitting into several droplets, the leading edge velocity at the time of ejection becomes the velocity of the leading droplet at the time of landing (hereinafter also referred to as the main droplet), and the trailing edge velocity at the time of ejection is It is considered that the velocity of the last droplet upon landing (hereinafter also referred to as satellite droplet) is obtained.
In general, when the droplet tip speed is 3 m / s or less, the droplet often does not break, and when the droplet tip speed is 3 to 20 m / s, the droplet often breaks.

The spacer is disposed on the substrate by drying the spacer dispersion liquid landed on the substrate by the above-described method.
The drying method is not particularly limited, and examples thereof include a method of heating the substrate, a method of blowing hot air, and the like, but in order to gather the spacer near the center of the landing droplet in the drying process, It is preferable to set the boiling point, the drying temperature, the drying time, the surface tension of the medium, the contact angle of the medium with respect to the alignment film, the concentration of the spacer, and the like under appropriate conditions.

In order to gather the spacers near the center of the landing droplets during the drying process, it is preferable to dry the spacers with a certain time width so that the liquid does not run out while the spacers move on the substrate. However, if the medium is in contact with the alignment film for a long time at a high temperature, the alignment film may be contaminated and the display image quality of the liquid crystal display device may be impaired. In addition, even when the substrate temperature is relatively low, the production efficiency of the liquid crystal display device is lowered when the drying time is remarkably increased. Furthermore, it is not preferable to use a medium that easily volatilizes at room temperature, because the spacer dispersion near the nozzles of the ink jet apparatus is easily dried and the ink jet discharge property is impaired. In addition, there is a possibility that aggregated particles are generated during the production of the dispersion or by drying in a tank.

In consideration of these conditions, in the manufacturing method of the liquid crystal display device, the substrate surface temperature when the spacer dispersion liquid lands on the substrate is 20 ° C. or more lower than the boiling point of the lowest boiling liquid contained in the spacer dispersion liquid. Preferably it is temperature. If the temperature exceeds 20 ° C. lower than the boiling point of the lowest-boiling liquid contained in the spacer dispersion liquid, this liquid will be volatilized rapidly and the spacer will not be able to move. The droplets may move around on the substrate, and the spacer placement accuracy may be significantly reduced.

In addition, when a drying method is adopted in which the medium is dried while the substrate temperature is gradually increased after the spacer dispersion liquid has landed on the substrate, the substrate surface temperature when the spacer dispersion liquid has landed on the substrate is determined by the spacer dispersion liquid. It is preferable that the temperature of the substrate surface is 20 ° C. or more lower than the boiling point of the lowest boiling liquid contained in the substrate, and the substrate surface temperature until the drying is completed does not exceed 90 ° C., and further does not exceed 70 ° C. preferable. When the substrate temperature when the droplets land exceeds 20 ° C. lower than the boiling point of the lowest boiling liquid contained in the spacer dispersion liquid, not only does this liquid volatilize and the spacer cannot move, In extreme cases, the liquid may suddenly boil and move around the substrate along with the droplets, and the spacer placement accuracy may be significantly reduced. Further, when the substrate temperature until the drying is completed exceeds 90 ° C., the alignment film may be contaminated and the display image quality of the liquid crystal display device may be impaired.
The completion of drying means the time when the droplets on the substrate disappear.

In the manufacturing method of the liquid crystal display device, the substrate on which the spacers are arranged in the above process is heat-pressed using an opposing substrate and a peripheral sealing material, and liquid crystal is filled in a gap between the two substrates.

The spacer used in the spacer dispersion of the present invention is not particularly limited, and examples thereof include inorganic silica fine particles and organic polymer fine particles. Among these, organic polymer fine particles have an appropriate hardness that does not damage the alignment film formed on the substrate of the liquid crystal display device, and can easily follow changes in thickness due to thermal expansion and contraction. This is preferable because the movement of the spacer inside the apparatus is relatively small.

The organic polymer-based fine particles are not particularly limited, and usually include those obtained by polymerizing a mixture of a monofunctional monomer and a polyfunctional monomer for reasons such as strength. The blending amount of the polyfunctional monomer in the mixture is preferably 30% by weight or less.
The monofunctional monomer is not particularly limited. For example, styrene derivatives such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene; vinyl chloride; vinyl acetate, vinyl propionate, etc. Vinyl esters of; unsaturated nitriles such as acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, And (meth) acrylic acid ester derivatives such as ethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, and cyclohexyl (meth) acrylate. These monofunctional monomers may be used alone or in combination of two or more.

The polyfunctional monomer is not particularly limited. For example, divinylbenzene, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylol. Propanetetra (meth) acrylate, diallyl phthalate and isomers thereof, triallyl isocyanurate and derivatives thereof, trimethylolpropane tri (meth) acrylate and derivatives thereof, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, Polyethylene glycol di (meth) acrylates such as dipentaerythritol hexa (meth) acrylate and ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate Polypropylene glycol di (meth) acrylate such as relate, polytetramethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 2,2-bis [4- 2,2-bis [4- (methacryloxypolyethoxy) phenyl] propane di (meth) acrylate such as (methacryloxyethoxy) phenyl] propanedi (meth) acrylate, 2,2-hydrogenated bis [4- (acryloxypoly) Ethoxy) phenyl] propanedi (meth) acrylate, 2,2-bis [4- (acryloxyethoxypolypropoxy) phenyl] propanedi (meth) acrylate, and the like. These polyfunctional monomers may be used alone or in combination of two or more.

The method for producing fine particles by polymerizing a mixture of the monofunctional monomer and polyfunctional monomer is not particularly limited, and examples thereof include suspension polymerization, seed polymerization, and dispersion polymerization.
The suspension polymerization 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.
Although the polymerization conditions in the suspension polymerization vary depending on the polymerization initiator and the type of the monomer, generally, the polymerization temperature is preferably 50 to 80 ° C., and the polymerization time is preferably 3 to 24 hours.
The above suspension polymerization is suitable for the purpose of producing fine particles having a plurality of particle sizes because the obtained particles have a relatively wide particle size distribution and polydisperse particles can be obtained.

The seed polymerization is a polymerization method in which a monodisperse seed particle synthesized by soap-free polymerization or emulsion polymerization is further absorbed with a polymerizable monomer to expand to a target particle diameter. The organic monomer used for the seed particles is not particularly limited, but the composition of the seed particles is preferably a material close to the monomer component at the time of seed polymerization in order to suppress phase separation at the time of seed polymerization, Styrene and its derivatives are preferred from the standpoint of monodispersity in the particle system distribution. Since the particle size distribution of the seed particles is reflected in the particle size distribution after seed polymerization, it is preferably monodispersed as much as possible, and is preferably 5% or less as the CV value. Since phase separation with seed particles is likely to occur during seed polymerization, the monomer absorbed during seed polymerization is preferably as close to the seed particle composition as possible. For example, it is preferable to absorb an aromatic divinyl monomer if the seed particles are styrene, and an acrylic multivinyl monomer if the seed particles are acrylic.
In the seed polymerization, 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. When the amount is less than 20 parts by weight, the fracture strength of the resulting crosslinked particles may be insufficient. When the amount exceeds 100 parts by weight, particle coalescence may occur during seed polymerization, and the particle size distribution may be widened.

In the seed polymerization, a dispersion stabilizer can be used as necessary. The dispersion stabilizer is preferably a polymer soluble in a 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.
The seed polymerization is suitable for the purpose of producing a large amount of fine particles having a specific particle diameter because monodispersed particles can be obtained without classification.

The above dispersion polymerization is a method of polymerizing in a poor solvent system in which the monomer dissolves but the produced polymer does not dissolve, and the resulting polymer is precipitated in a particle shape by adding a polymer dispersion stabilizer to this system. It is. In general, when the cross-linking component is polymerized by dispersion polymerization, it is difficult to obtain stable monodisperse cross-linked particles because the particles tend to aggregate. However, it is possible to polymerize the monomer containing the cross-linking component by selecting the conditions. It becomes. However, from the viewpoint of aggregation during polymerization and strength, the crosslinkable monomer is preferably 50% by weight or more based on the total monomers. When the amount of the crosslinkable monomer is less than 50% by weight based on the total monomer, the surface of the fine particles formed at the time of polymerization is soft in the solvent. In some cases, it may be widened or aggregated, and even if the monodispersity is maintained, if the crosslinking density is low, sufficient breaking strength as a spacer may not be obtained.
The dispersion polymerization is suitable for the purpose of producing a large amount of fine particles having a specific particle diameter because monodispersed particles can be obtained without classification.

A polymerization initiator is used in the polymerization. Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate And organic peroxides such as di-t-butyl peroxide, and azo compounds such as azobisisobutyronitrile, azobiscyclohexacarbonitrile, and azobis (2,4-dimethylvaleronitrile). In general, the amount of the polymerization initiator used is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

The medium used in the polymerization should be appropriately determined depending on the polymerizable monomer to be used, but alcohols, cellosolves, ketones or hydrocarbons are suitable, for example, acetonitrile, N, N -Dimethylformamide, cymethyl sulfoxide, ethyl acetate; alcohols such as methanol, ethanol, propanol; cellosolves such as methyl cellosolve, ethyl cellosolve; ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, 2-butanone, etc. . These media may be used independently and may use 2 or more types together.

Since the spacer is used as a gap material of a liquid crystal display device, a certain strength is required, and a preferable lower limit of the compressive elastic modulus (hereinafter also referred to as 10% K value) when the diameter is displaced by 10% is 2000 MPa, A preferred lower limit is 15000 MPa. If the pressure is less than 2000 MPa, the spacer may be deformed due to the press pressure when assembling the liquid crystal display device, and an appropriate gap may not be obtained. If the pressure exceeds 15000 MPa, the alignment film on the substrate may be damaged and display anomalies may occur. There is.
The 10% K value is determined by using a micro compression tester (such as Shimadzu PCT-200) in accordance with Japanese Patent Publication No. 6-503180 and using a smooth end face of a 50 μm diameter cylinder made of diamond. It can be obtained from the weight for distorting 10%.

The spacer may be colored and used for improving the contrast of the liquid crystal display device. Examples of the colored spacer include those treated with carbon black, disperse dyes, acid dyes, basic dyes, metal oxides, and the like, and organic films are formed on the surface and decomposed or carbonized at high temperatures to be colored. And the like.
In addition, when the material itself which forms a spacer has a color, you may use as it is, without coloring.

The spacer may be provided with an adhesive layer on the surface, or may be subjected to surface modification so as not to disturb the alignment of the surrounding liquid crystal.
As a method for performing the surface modification, for example, as disclosed in JP-A-1-247154, a resin is deposited on the spacer surface for modification, and as disclosed in JP-A-9-11915. And a method in which a compound reacting with a functional group on the surface of the spacer is allowed to act, and a method in which the surface is modified by graft polymerization on the spacer surface as disclosed in JP-A-11-223821. A method of forming a surface layer chemically bonded to the spacer surface is preferable because peeling of the surface layer in the cell of the liquid crystal display device and elution into the liquid crystal can be prevented. Among them, the method disclosed in JP-A-9-113915, in which graft polymerization is performed on the surface by reacting an oxidant with a spacer having a reducing group on the surface to generate radicals, increases the density of the surface layer. It is preferable because it can be formed with a high and sufficient thickness.

The spacer dispersion liquid of the present invention is obtained by dispersing the spacer in a medium.
As the medium of the spacer dispersion liquid of the present invention, various compounds that are liquid at room temperature can be used. Of these, a water-soluble or hydrophilic liquid is preferable. In addition, since the heads of some ink jet devices are made for water-based applications, when these heads are used, a strong hydrophobic solvent may cause adhesion of liquids to the members constituting the heads or adhesion of the members. It is not preferable because a part of the agent is dissolved.
In addition, a resin thin film made of a polyamide resin or the like called an alignment film for regulating the alignment of liquid crystal molecules is usually formed on the surface of a substrate used in a liquid crystal display device. It must not be contaminated with the alignment film that penetrates or dissolves in it.

Examples of the water-soluble or hydrophilic liquid include pure water, ethanol, n-propanol, 2-propanol, 1-butanol, 2-butanol, 1-methoxy-2-propanol, furfuryl alcohol, and tetrahydrofluor. Examples include monoalcohols such as furyl alcohol.
In addition, ethylene glycol multimers such as ethylene glycol, diethylene glycol recall, triethylene glycol and tetraethylene glycol; lower monoalkyl ethers such as monomethyl ether, monoethyl ether, monoisopropyl ether, monopropyl ether and monobutyl ether; Examples include lower dialkyl ethers such as dimethyl ether, diethyl ether, diisopropyl ether, and dipropyl ether; alkyl esters such as monoacetate and diacetate.
In addition, a multimer of propylene glycol such as propylene glycol, dipropylene glycol recall, tripropylene glycol, tetrapropylene glycol; or lower monomonomers such as monomethyl ether, monoethyl ether, monoisopropyl ether, monopropyl ether, monobutyl ether, etc. Alkyl ethers; lower dialkyl ethers such as dimethyl ether, diethyl ether, diisopropyl ether, and dipropyl ether; and 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 Diols such as 1,5-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 1,6-hexanediol, neopentylglycol, and the like Ether derivatives of diols, acetate derivatives of diols, glycerin, 1,2,4, -butanetriol, 1,2,6-hexanetriol, 1,2,5, -pentanetriol, trimethylolpropane, trimethylolethane, penta And polyhydric alcohols such as erythritol or ether derivatives thereof, acetate derivatives, etc.
Further, dimethyl sulfoxide, thiodiglycol, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, r-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- Examples include diethylethanolamine, abiethinol, diacetone alcohol, urea and the like.

The spacer dispersion medium of the present invention preferably contains a liquid having a boiling point of less than 100 ° C. More preferably, the organic solvent has a boiling point of 70 ° C. or higher and lower than 100 ° C.
Examples of such an organic solvent include lower monoalcohols such as ethanol, n-propanol, and 2-propanol; acetone and the like. When such an organic solvent is used, it can be volatilized at a relatively low temperature when the spacer dispersion liquid is discharged onto the substrate and then dried.
In the manufacturing method of the liquid crystal display device using the spacer dispersion liquid of the present invention, when a high-temperature medium comes into contact with the alignment film, the alignment film is contaminated and the display image quality of the liquid crystal display device is deteriorated, so that the drying temperature cannot be so high. Therefore, it is preferable to use a liquid having a relatively low boiling point.
The preferable lower limit of the content of the liquid having a boiling point of less than 100 ° C. is 10% by weight, and the preferable upper limit is 80% by weight. If it is less than 10% by weight, the drying speed at a relatively low drying temperature may be slow and the production efficiency may be reduced. If it exceeds 80% by weight, the spacer dispersion near the nozzles of the ink jet device is easily dried. In some cases, the properties may be impaired, and it is easy to dry in the production of the spacer dispersion liquid or in the tank.
In the present invention, the boiling point refers to the boiling point at 1 atm.

The liquid having a boiling point of less than 100 ° C. preferably has a surface tension at 20 ° C. of 25 mN / m or less. A general inkjet device exhibits good ejection accuracy when the surface tension of the liquid to be ejected is 30 to 50 mN / m. On the other hand, a higher surface tension of the dispersed liquid droplets discharged onto the substrate is suitable for moving the spacer during the drying process. When the surface tension of the liquid having a boiling point of less than 100 ° C. is 25 mN / m or less, since the surface tension of the spacer dispersion liquid is relatively low at the time of discharge, good discharge accuracy can be obtained and after landing on the substrate Volatilizes prior to the other components in the spacer dispersion liquid, and the surface tension of the dispersion liquid increases, and the spacer tends to move toward the center of the landing point.

The spacer dispersion medium of the present invention preferably contains a liquid having a boiling point of 150 ° C. or higher. More preferably, it is an organic solvent at 150 ° C. or higher and 200 ° C. or lower.
Examples of such an organic solvent include lower alcohol ethers such as ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol, and dimethyl ether. By containing such a liquid, the spacer dispersion liquid is excessively dried in the vicinity of the nozzles of the ink jet device and the discharge accuracy is lowered, or the spacer dispersion liquid is dried during the production of the spacer dispersion liquid or in the tank, and aggregated particles are generated. Can be suppressed.
The preferable lower limit of the content of the liquid having a boiling point of 150 ° C. or higher is 10% by weight, and the preferable upper limit is 80% by weight. If it is less than 10% by weight, the discharge accuracy of the spacer dispersion liquid is reduced and the generation of aggregated particles tends to occur. If it exceeds 80% by weight, not only the drying time is remarkably reduced but also the efficiency is lowered. The display image quality of the liquid crystal display device is likely to deteriorate due to contamination of the liquid crystal display.

The liquid having a boiling point of 150 ° C. or higher preferably has a surface tension at 20 ° C. of 30 mN / m or higher. Thereby, after the liquid droplets of the spacer dispersion liquid land on the substrate and the liquid having a lower boiling point evaporates, the surface tension of the spacer dispersion liquid is kept high, and the spacer easily moves.

The preferable lower limit of the viscosity of the spacer dispersion of the present invention is 0.5 mPa · s, and the preferable upper limit is 15 mPa · s. If the pressure is less than 0.5 mPa · s, it may be difficult to control the discharge amount, and stable discharge may not be possible. If the pressure exceeds 15 mPa · s, the ink jet apparatus may not be able to discharge. A more preferred lower limit is 5 mPa · s, and a more preferred upper limit is 10 mPa · s. The liquid temperature at the time of discharging the spacer dispersion liquid may be adjusted, for example, by controlling the head temperature of the ink jet apparatus between −5 to 50 ° C. so as to be in a preferable viscosity range.

The preferable lower limit of the spacer concentration in the spacer dispersion of the present invention is 0.05% by weight, and the preferable upper limit is 5% by weight. If it is less than 0.05% by weight, there is a high probability that the ejected droplet does not contain a spacer. If it exceeds 5% by weight, the nozzle of the ink jet device is likely to close or In some cases, the number of spacers included in the plate increases so that the movement of the spacers is difficult to occur during the drying process. A more preferred lower limit is 0.1% by weight, and a more preferred upper limit is 2% by weight.

In the spacer dispersion liquid of the present invention, the spacers are preferably dispersed in the form of single particles. When aggregates are present in the spacer dispersion liquid, not only the ejection accuracy is lowered, but in the case of remarkable, the nozzles of the ink jet apparatus may be clogged.

The spacer dispersion liquid of the present invention further includes an adhesive component for imparting adhesiveness, the dispersion of the spacer is improved, the physical properties such as surface tension and viscosity are controlled to improve the discharge accuracy, and the mobility of the spacer. Various surfactants, viscosity modifiers and the like may be added for the purpose of improving the viscosity.

The substrate used in the method for producing a liquid crystal display device using the spacer dispersion of the present invention is not particularly limited, and examples thereof include those generally used as a panel substrate for liquid crystal display devices such as glass and resin plates.

In the manufacturing method of the liquid crystal display device, the relative velocity V ₁ between the head and the substrate, the substrate surface of the spacer dispersion liquid ejected from the nozzle of the ink jet device is set so that the landing distance l is larger than 40 μm with respect to the substrate surface. And the angle θ formed by the droplet ejection direction, the time t required from the time when the leading edge of the droplet is ejected from the head ejection port to the time when the trailing edge is completely ejected, the distance L between the droplet ejection port of the head and the substrate, Since the velocity V ₂ at the leading end of the droplet and the velocity V ₃ at the trailing end of the droplet are controlled, the droplet shape at the time of landing becomes elliptical or the droplet breaks up. Becomes narrower and easily fits in the non-display portion of the panel.
As a result, in the method for manufacturing a liquid crystal display device using the spacer dispersion liquid of the present invention, the spacers can be selectively disposed in the non-display portion having a narrow width, and light leakage or light leakage occurs from the periphery of the spacers. Therefore, it is possible to efficiently manufacture an excellent liquid crystal display device in which the display image quality is not deteriorated by the above.

According to the present invention, a spacer can be accurately arranged on a non-display portion of a liquid crystal display device substrate, and a spacer capable of manufacturing a liquid crystal display device having high display quality that prevents light leakage and light leakage by the spacer. A dispersion can be provided.

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

Example 1
(Preparation of spacer fine 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, and then polyvinyl alcohol (GL-03, manufactured by Kuraray Co., Ltd.) After adding 20 parts by weight of a 3% aqueous solution and 0.5 parts by weight of sodium dodecyl sulfate and stirring well, 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 fine particles were washed with hot water and acetone, and then classified, and acetone was volatilized to obtain fine particles. The obtained fine particles had an average particle size of 5.0 μm and a CV value of 3.0%.

(Spacer surface treatment)
5 parts by weight of the obtained fine particles were put into 20 parts by weight of dimethyl sulfoxide (DMSO) and 20 parts by weight of hydroxy methacrylate, dispersed with a sonicator, and then uniformly stirred. Nitrogen gas was introduced into the reaction system and stirring was continued at 30 ° C. for 2 hours. To this was added 10 parts by weight of a 0.1 mol / L ceric ammonium nitrate solution prepared with a 1N nitric acid aqueous solution, and the reaction was continued for 5 hours. After completion of the polymerization reaction, the reaction solution was taken out, and the particles and the reaction solution were separated by a 3 μm membrane filter. The particles were thoroughly washed with ethanol and acetone, and dried under reduced pressure in a vacuum dryer to obtain a spacer.

(Preparation of spacer dispersion)
A spacer dispersion is prepared by taking a necessary amount of the obtained spacer so as to have a predetermined spacer concentration, adding it slowly to a dispersion medium having the composition shown in Table 1, and dispersing it by sufficiently stirring while using a sonicator. did.
The obtained spacer dispersion was filtered through a stainless steel mesh having a mesh size of 10 μm to remove aggregates and subjected to evaluation with an ink jet apparatus.

(Spacer placement by inkjet method)
The ink was ejected onto a substrate heated to 80 ° C. by an ink jet apparatus equipped with a piezo head having a diameter of 40 μm. The substrate was heated by heating the stage with a heater attached to the stage.
Table 2 shows the values of each parameter in the spacer dispersion discharge.
In addition, as a substrate, a solution containing polyimide (Sanever 150, manufactured by Nissan Chemical Co., Ltd.) was uniformly applied by spin coating on a color filter substrate having an ITO transparent electrode on the surface, dried at 150 ° C., and then 230 An alignment film was formed by baking and curing at 1 ° C. for 1 hour. In this color filter substrate, a black matrix having a width of 25 μm is formed between the pixels of the color filter (vertical 150 μm × horizontal 75 μm pitch), and every other vertical line of the black matrix is arranged at 110 μm intervals by an inkjet device. It was supposed to be placed. That is, they are arranged at a pitch of 110 μm × 150 μm.
The dispersion density of the spacers arranged in this way was 200 pieces / mm ² .

After confirming that the spacer dispersion liquid discharged onto the substrate was completely dried by visual observation, the substrate was transferred onto a hot plate heated to 150 ° C. for further drying and for fixing the spacer to the substrate. And heated for 30 minutes.

The substrate on which the obtained spacer is arranged and the counter substrate are bonded together using a peripheral sealing material, and the sealing material is cured by heating at 150 ° C. for 1 hour to produce an empty cell having a cell gap of 5 μm. Liquid crystal was filled by the method, and the inlet was sealed with a sealing agent to prepare a liquid crystal display device.

About the obtained liquid crystal display device, display image quality was evaluated according to the following criteria.
A: Almost no spacer was observed in the display area, and there was no light leakage due to the spacer, and the image was good.
Δ: Some spacers were observed in the display area, and light leakage due to the spacers was observed.
X: Many spacers were recognized in the display area, and there was light leakage due to the spacers.
The results are shown in Table 2.

(Examples 2 to 8)
A liquid crystal display device was produced in the same manner as in Example 1 except that the dispersion liquid and the inkjet discharge control parameters were as shown in Table 2, and the display image quality was evaluated.
The results are shown in Table 2.

(Comparative Examples 1-3)
A liquid crystal display device was produced in the same manner as in Example 1 except that the dispersion liquid and the inkjet discharge control parameters were as shown in Table 2, and the display image quality was evaluated.
The results are shown in Table 2.

(Examples 9 and 10)
A liquid crystal display device was manufactured and the display image quality was evaluated in the same manner as in Examples 4 and 8, except that the landing position of the droplets of the spacer dispersion liquid was adjusted so as to be on the intersection of the black matrix. Was better than Examples 4 and 8.

According to the present invention, a spacer can be accurately arranged on a non-display portion of a liquid crystal display device substrate, and a spacer capable of manufacturing a liquid crystal display device having high display quality that prevents light leakage and light leakage by the spacer. A dispersion can be provided.

It is a schematic diagram which shows the structure of the conventional liquid crystal display device. It is a schematic diagram showing a landing state when droplets of a spacer dispersion liquid are landed on a substrate by a conventional spacer dispersion liquid discharge method. It is a schematic diagram which shows a landing state when the droplet of spacer dispersion liquid is made to land on a board | substrate with the discharge method of the spacer dispersion liquid which concerns on this invention. It is a schematic diagram which shows a mode that the droplet discharged from the nozzle lands on a board | substrate, without dividing | segmenting. It is a schematic diagram which shows a mode that the droplet discharged from the nozzle is split in the air and landed on the substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Polarizing plate 3 Transparent electrode 4 Color filter 5 Black matrix 6 Overcoat 7 Liquid crystal 8 Spacer 9 Alignment film 10 Landing droplet

Claims (5)

A spacer dispersion used in a manufacturing method of a liquid crystal display device in which spacers are arranged at arbitrary positions on a substrate by an inkjet method,
At least a spacer and a medium are contained, and a liquid having a boiling point of less than 100 ° C. is contained as the medium in an amount of 10 to 80% by weight, and the spacer content is 0.05 to 5% by weight in a temperature range of −5 to 50 ° C. A spacer dispersion having a viscosity of 0.5 to 15 mPa · s. A spacer dispersion used in a manufacturing method of a liquid crystal display device in which spacers are arranged at arbitrary positions on a substrate by an inkjet method,
At least a spacer and a medium are contained, and a liquid having a boiling point of 150 ° C. or higher is contained as the medium in an amount of 10 to 80% by weight. A spacer dispersion having a viscosity of 0.5 to 15 mPa · s. A spacer dispersion used in a manufacturing method of a liquid crystal display device in which spacers are arranged at arbitrary positions on a substrate by an inkjet method,
At least a spacer and a medium are contained, and the medium contains 10 to 80% by weight of a liquid having a boiling point of less than 100 ° C. and 80 to 10% by weight of a liquid having a boiling point of 150 ° C. or more, and the spacer content is 0.05 to A spacer dispersion liquid having a viscosity in a temperature range of 5 wt% and -5 to 50 ° C of 0.5 to 15 mPa · s. Liquids having a boiling point of 150 ° C. or higher are ethylene glycol, propylene glycol, 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-pentanediol, 2,5-hexanediol, 1,6-hexane The spacer dispersion liquid according to claim 2 or 3, wherein the spacer dispersion liquid is at least one selected from the group consisting of a diol and neopentyl glycol. A liquid crystal display device comprising the spacer dispersion liquid according to claim 1, 2, 3 or 4.

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