JP2003043494A - Spacer for liquid crystal display element and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide spacers for liquid crystal display element having a small quantity of plastic deformation when holding compression load, excellent in particle size distribution and having a small quantity of mixed large size particles and to provide a liquid crystal display element using the spacers. SOLUTION: In the spacers for liquid crystal display element, the ratio (ΔL/D) of an indenter movement quantity ΔL during load holding time, when 17 mN load is applied to an optional particle at 0.28 mN/s loading speed and the load is held for 30 seconds, to the particle size R of the particle is <=0.02 and the mixed quantity of the particles having the particle size 1.26 times as large as the average particle size or more is <=1 ppm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spacer for a liquid crystal display device, which has a small amount of plastic deformation while retaining a compressive load, an excellent particle size distribution, and a small amount of large particles mixed therein, and a liquid crystal display device using the spacer.

[0002]

2. Description of the Related Art A liquid crystal display device is composed of two corresponding electrode substrates, a spacer for a liquid crystal display device and a liquid crystal substance interposed between the electrode substrates. The spacer for a liquid crystal display device is used to keep the thickness of the liquid crystal layer uniform and constant.

Conventionally, as the display performance which is practically required for a liquid crystal display element, high-speed response, high contrast and high viewing angle have been mentioned. However, liquid crystal display devices used in mobile devices, mobile phones, and the like, which are in great demand in recent years, are also required to have compression resistance and vibration resistance. For example, mobile phones are often carried in clothes pockets, bags, etc., but when a load is locally applied to the liquid crystal display element for a long time, the spacer for the liquid crystal display element is plastically deformed. As a result, a gap in the liquid crystal display element may occur and display defects may occur. In order to improve the compression resistance of the liquid crystal display element, it is necessary to reduce the gap unevenness due to the permanent deformation of the spacer for the liquid crystal display element, that is, the amount of plastic deformation.

Inorganic or organic particles are generally used as spacers for liquid crystal display elements. The particles used as the spacers for the liquid crystal display device have a K value of 120 so as not to physically damage the coating layers such as electrodes, alignment film and color filter on the substrate during the production of the liquid crystal display device.
It is preferably 00 N / mm ² or less. However, if it is too soft, a uniform gap cannot be maintained when a liquid crystal display device is manufactured by pressing, which causes display unevenness. Therefore, a hardness not to damage an alignment film on the liquid crystal display device during fabrication, and as the K value can keep a uniform gap preferably 5000~12000N / mm ^2, more preferably 6000~9000N / mm ^2.

As the inorganic particle spacer for a liquid crystal display device, for example, JP-A-63-73225 discloses a spacer made of silicon dioxide. However, the conventional inorganic particle spacers for liquid crystal display elements have too high hardness, so that pressing when manufacturing a liquid crystal display element causes physical damage to the electrodes on the substrate, the alignment film, and the coating layers such as color filters. However, there is a problem in that image unevenness and pixel defects occur.

As the spacer of the above-mentioned organic particles for a liquid crystal display element, for example, a spacer made of a penzoguanamine-based polymer is disclosed in JP-A-60-200228.
Japanese Patent Laid-Open No. 293316 discloses a material made of a polystyrene-based polymer. These have a suitable hardness that does not damage the alignment film even when pressed during the production of a liquid crystal display element, and have the characteristic of easily following changes in the liquid crystal due to thermal expansion or contraction, but when a load is applied for a long time. However, there is a problem that display unevenness is likely to occur when used in mobile devices, mobile phones, etc.

Japanese Unexamined Patent Publication (Kokai) No. 5-148328 discloses, as one of the methods for improving the strength of a spacer for a liquid crystal display element, a vinyl monomer containing a vinyl monomer having a nitrile group and a crosslinkable vinyl monomer. A method for obtaining crosslinked polymer particles by polymerizing a body mixture with a relatively large amount of an organic oxide-based radical polymerization initiator in an aqueous medium is disclosed. Further, Japanese Patent Application Laid-Open No. 7-2913 discloses a technique similar to the above with respect to a pigment-dispersed light-shielding liquid crystal display element spacer.

However, although these methods can improve the hardness of the spacer for a liquid crystal display element, they are not very effective in improving the amount of plastic deformation during holding a compressive load.
Further, there is an inherent process problem that vinyl monomers having a nitrile group are practically limited to acrylonitrile and methacrylonitrile. Particularly, acrylonitrile is described as having a remarkably excellent effect, but it is specified as a specific chemical substance, and when used on an industrial scale, there is a concern that the working environment and the surrounding environment may deteriorate.

In Japanese Patent Laid-Open No. 10-139830, a polyfunctional acrylic monomer having a functionality of 3 or more is used as an organic peroxide-based radical polymerization initiator in a method of manufacturing a spacer for a liquid crystal display device having an excellent recovery rate and a relatively high hardness. A method of polymerizing is disclosed. However, although this method can improve hardness and recovery rate, the effect of suppressing plastic deformation is not sufficient.

As a problem of using inorganic or organic particles as a spacer for a liquid crystal display element, there is a problem of variation in particle diameter. In particular, when a large amount of particles having a particle diameter of 1.26 times or more of the average particle diameter, which are called large particles, is mixed, the large particles support the substrate, resulting in gap unevenness and spacer destruction. At present, spacers in which the amount of plastic deformation when a load is continuously applied for a long time are sufficiently small and the amount of large particles mixed in is 1 ppm or less have not been supplied to the market.

Conventionally, a method for measuring the amount of plastic deformation of a spacer for a liquid crystal display element has not been specified. As a method for evaluating compression resistance, a liquid crystal display element is manufactured and a load is applied to the liquid crystal display element. In addition, there is only a method of evaluating display unevenness after removing the load, and there is a problem that the evaluation takes time and man-hours.

[0012]

DISCLOSURE OF THE INVENTION In view of the above situation, the present invention provides a spacer for a liquid crystal display device, which has a small amount of plastic deformation during holding a compressive load, an excellent particle size distribution, and a small amount of large particles mixed therein. It is intended to provide a liquid crystal display element used.

[0013]

Means for Solving the Problems The present inventors have found that a spacer for a liquid crystal display element, which has a small amount of plastic deformation when a compressive load is held, has an excellent particle size distribution, and has a small amount of large particles mixed therein, is used as a spacer for a liquid crystal display element. They have found that they are effective in improving compressibility and vibration resistance, and have completed the present invention.

The present invention provides 0.28 m for any one particle.
Indenter movement amount Δ during load holding time when a load of 17 mN was applied at a load speed of N / S and the load was held for 30 seconds
The ratio (ΔL / R) of L to the particle diameter R of the particle is 0.0
The spacer for a liquid crystal display device is 2 or less, and the mixing amount of particles having a particle diameter of 1.26 times or more the average particle diameter is 1 ppm or less. The present invention is described in detail below.

The spacer for a liquid crystal display device of the present invention is not particularly limited, but a polymer having a high molecular weight is preferable because it is easy to obtain a spacer having appropriate elasticity, flexibility and recoverability. The high molecular weight material is not particularly limited,
For example, phenol resin, amino resin, acrylic resin,
Ethylene-vinyl acetate resin, styrene-butadiene block copolymer, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, urethane resin,
Thermoplastic resins such as epoxy resins; curable resins, crosslinked resins, organic-inorganic hybrid polymers and the like.

The recovery rate is one of the methods for evaluating the mechanical properties of the spacer for a liquid crystal display device. This is an evaluation method in which a load of 10 mN is applied to any one particle and the displacement amount of the liquid crystal display element spacer when the load is removed is measured. In this measurement of the recovery rate, the load begins to be removed at the moment when the maximum load is applied, and therefore the creep characteristic peculiar to the polymer material cannot be evaluated. The creep property is a property caused by elastic deformation and plastic deformation of a high molecular weight substance, and the amount of creep can be measured by holding the polymer under a certain load. When a load is applied to the liquid crystal display element, if the spacer for the liquid crystal display element is deformed only by elastic deformation, the original shape is completely restored even after the load is removed, so that no gap unevenness occurs. However, when plastic deformation occurs due to the creep phenomenon while holding the load, the original shape cannot be completely restored even after the load is removed, resulting in gap unevenness. Therefore, it is possible to improve the compression resistance of the spacer for a liquid crystal display element by reducing the amount of plastic deformation due to this creep characteristic.

The present inventor has found that the plastic deformation amount of the spacer for a liquid crystal display device is 0.28 mN / s for any one particle.
It was found that the load can be evaluated by applying a load of 17 mN at a load speed of, holding the load for 30 seconds, and measuring the indenter movement amount ΔL during that time. Further, the inventor has found that the amount of plastic deformation greatly changes depending on the particle size, and it becomes a large value when a particle having a large average particle size is measured.
It has been found that the compression resistance of the spacer for a liquid crystal display device can be evaluated regardless of the particle size by measuring the ratio ΔL / R of L to the particle size R.

Any one particle of the spacer for a liquid crystal display element of the present invention has a particle size of 17 m at a load speed of 0.28 mN / S.
The ratio (ΔL / R) between the indenter movement amount ΔL and the particle size R of the particles during the load holding time when the load of N is applied and the load is held for 30 seconds is 0.02 or less. If it exceeds 0.02, the amount of plastic deformation during holding a compressive load is large, resulting in gap unevenness.

The method of measuring the indenter movement amount ΔL is not particularly limited, and it can be measured by, for example, an ultrafine hardness test system (Fisherscope H-100) manufactured by Fisher Instruments. . 0.28 mN / for any one particle using this tester
The load is gradually applied at a load speed of s, and the load is 17 mN
At that time, the load is held for 30 seconds and the indenter movement amount ΔL during that time is measured. Further, the particle size R of the particles used for the measurement is measured, and the ratio of the indenter movement amount ΔL to the particle size R (Δ
L / R) can be calculated.

In the spacer for a liquid crystal display device of the present invention, the amount of large particles having a particle diameter of 1.26 times or more the average particle diameter is 1 ppm or less. When it exceeds 1 ppm, the load is supported by the large particles, and since these large particles do not exist due to the continuous distribution of the particle size, when the load is applied to the liquid crystal display element. Will be subjected to a very strong stress on those large particles, and may be destroyed if the load value is large. When the spacer for a liquid crystal display element is broken, fragments are scattered on the liquid crystal layer, and the orientation of the liquid crystal molecules is disturbed by them, which causes display failure.

When a load is applied to the liquid crystal display element, it is possible to reduce the amount of load applied to one particle by supporting the load with more particles, and as a result, the spacer for the liquid crystal display element is reduced. The amount of plastic deformation can be reduced. The present inventor has found that the particles supporting the cell gap of the liquid crystal display element are particles on the relatively large particle side of the particle size distribution, and therefore the narrower the particle size distribution of the particles, the larger the particle size distribution. It was found that the sharper the rise on the side, the higher the compression resistance. The spacer for a liquid crystal display element of the present invention preferably has a CV value represented by the following formula of 3% or less. If it exceeds 3%, the above-mentioned effects cannot be obtained and gap unevenness may occur. CV (%) = average particle size (μm) / standard deviation (μm) × 1
In the present specification, the CV value refers to a value obtained from an average value of particle diameters and standard deviations obtained by measuring about 40,000 particles using a Coulter counter.

The average particle size of the spacer for a liquid crystal display device of the present invention is preferably 1 to 20 μm. If it is out of this range, the gap between the electrode substrates of the liquid crystal display element may be inappropriate for injecting liquid crystal. More preferably 1
It is 15 μm.

The method for producing the spacer for a liquid crystal display device of the present invention is not particularly limited, and examples thereof include emulsion polymerization method, suspension polymerization method, precipitation polymerization method, seed polymerization method and soap-free polymerization method. Among them, the suspension polymerization method and the seed polymerization method are preferable when the production is carried out on an industrial scale. From the viewpoint of particle size distribution and the amount of large particles mixed, seed polymerization is more preferable. Seed polymerization is a method in which seed particles prepared by soap-free polymerization or dispersion polymerization are allowed to absorb a polymerizable monomer and a radical polymerization initiator, and then polymerization is performed. In this seed polymerization method, since the seed particles are produced by soap-free polymerization or dispersion polymerization, monodisperse particles having an excellent particle size distribution can be obtained. Further, the large particles generated during the polymerization are generated by the coalescence of the seed particles and exist as a discrete distribution instead of a continuous distribution. Therefore, it is also very easy to remove the large particles in a post process.

The polymerizable monomer used in the preparation of the seed particles is not particularly limited, and examples thereof include styrene derivatives such as styrene, α-methylstyrene, P-methylstyrene, P-chlorostyrene and chloromethylstyrene; Ethyl derivatives such as vinyl chloride, vinyl bromide and ethylene; vinyl ester cheeks such as vinyl acetate and vinyl propionate; unsaturated nitrile cheeks such as acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, (meth) acrylic acid-2-
Monofunctional such as (meth) acrylic acid ester derivatives such as ethylhexyl, stearyl (meth) acrylate, ethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate and cyclohexyl (meth) acrylate Examples include monomers. These monomers may be used alone or in combination of two or more. In this specification, (meth) acrylic acid means acrylic acid or methacrylic acid, and (meth) acrylate means acrylate or methacrylate.

The weight average molecular weight of the seed particles is not particularly limited, but is preferably 30,000 or less. If it exceeds 30,000, the mechanical strength may be significantly reduced due to phase separation from the crosslinking component added during seed polymerization. It is more preferably 25,000 or less. The method for obtaining the weight average molecular weight in the above range is not particularly limited, for example,
Known techniques such as a method of adding a chain transfer agent and a method of adjusting the addition amount of a polymerization initiator can be used.

The polymerizable monomer to be absorbed by the seed particles is not particularly limited, and examples thereof include styrene derivatives such as styrene, α-methylstyrene, P-methylstyrene, P-chlorostyrene and chloromethylstyrene; vinyl chloride. Ethylene derivatives such as vinyl bromide and ethylene; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated nitriles such as acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid Butyl, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, ethylene glycol (meth) acrylate, trifluoroethyl (meth)
Examples thereof include monofunctional monomers such as (meth) acrylic acid ester derivatives such as acrylate, pentafluoropropyl (meth) acrylate, and cyclohexyl (meth) acrylate. Further, divinylbenzene; polyethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate. Examples thereof include polyfunctional monomers such as acrylate and tetramethylolmethanetetra (meth) acrylate; diallylphthalate and its derivatives; and polyfunctional monomers such as triallyl isocyanurate and its derivatives. These polymerizable monomers may be used alone or in combination of two or more.

The polymerizable monomer to be absorbed by the seed particles should contain 40% by weight or more of a crosslinkable monomer having two or more unsaturated double bonds in the molecule, based on the total amount of the monomers. Is preferred. This makes it possible to obtain a liquid crystal display element spacer having higher strength. More preferably, it is 60% by weight or more.

The amount of the polymerizable monomer added is preferably 20 to 120 parts by weight with respect to 1 part by weight of the seed particles. If the amount is less than 20 parts by weight, the phase separation between the seed particles and the cross-linking component may be remarkable and the mechanical strength may be significantly reduced. If the amount is more than 120 parts by weight, polymerizable monomers that cannot be completely absorbed are generated. However, the particle size distribution may deteriorate.

The polymerization initiator and the polymerization temperature used for the seed polymerization are not particularly limited, but a peroxide radical polymerization initiator having a decomposition temperature of 85 to 170 ° C. for obtaining a half-life of 10 hours is used. From the viewpoint of the mechanical strength of the spacer for a liquid crystal display device, it is preferable to carry out the polymerization reaction at a temperature higher by 10 ° C. or more than the decomposition temperature for obtaining the half-life of 10 hours of the polymerization initiator. Generally, when a peroxide type initiator is used as an initiator in a radical polymerization reaction, highly active hydrogen is extracted from a polymer produced as a side reaction to generate a radical in the polymer. Polymerization proceeds from the generated radicals, and the product becomes a polymer having a crosslinked structure. This reaction is more likely to proceed at higher temperatures, but when a radical polymerization initiator having a high activity at a low temperature is used and the polymerization is carried out at a high temperature of 95 ° C or higher, for example, the growth reaction of the polymer remarkably increases. Since the reaction is promoted and the above reaction hardly occurs, it is impossible to obtain a spacer for liquid crystal display element having high strength. Further, when polymerization is carried out using an azo radical polymerization initiator, the hydrogen abstraction reaction does not occur, and therefore the strength of the spacer for a liquid crystal display element cannot be increased. On the other hand, a peroxide radical polymerization initiator having a decomposition temperature of 85 to 170 ° C. for obtaining a half-life of 10 hours is used, and the decomposition temperature for obtaining the half-life of 10 hours of the polymerization initiator is Further, when the polymerization reaction is further performed at a temperature higher by 10 ° C. or more, the hydrogen abstraction reaction is promoted and the growth reaction of the polymer proceeds gently. Therefore, the obtained spacer for a liquid crystal display device has an increased cross-linking structure in the particles and thus has higher strength.

When two or more of the above-mentioned polymerization initiators are used in combination, it is preferable to carry out the polymerization at a temperature higher than the 10-hour half-life temperature by 10 degrees or more, based on the initiator having the lowest 10-hour half-life temperature. .

When the polymerization is carried out in an aqueous system, the polymerization temperature is 1
When the temperature is higher than 00 ° C, water as a solvent boils and stable polymerization cannot be carried out. Therefore, when the polymerization temperature exceeds 100 ° C, it is preferable to carry out the polymerization using a pressure resistant polymerization vessel.

The above-mentioned polymerization initiator is not particularly limited as long as it has a decomposition temperature of 85 to 170 ° C. for obtaining a half-life of 10 hours, and it is not particularly limited. , 1-bis (t-hexylperoxy)
-3,3,5-Trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1
-Bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, t-butylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, cumene hydroperoxide, dicumyl peroxide and the like can be mentioned. These polymerization initiators may be used alone or in combination of two or more kinds.

The amount of the polymerization initiator added is preferably 1 to 10 parts by weight based on the total amount of the monomers. When it is less than 1 part by weight, the polymerization rate is lowered and the production amount per hour is lowered, which may cause a problem in production efficiency. When it is more than 10 parts by weight, the polymerization reaction may run away. It is more preferably 3 to 7 parts by weight.

In the above-mentioned seed polymerization, a dispersion stabilizer can be used if necessary. The dispersion stabilizer is not particularly limited, and surfactants such as sodium lauryl sulfate, sodium lauryl benzene sulfonate, sodium polyoxyethylene lauryl ether sulfate; gelatin, starch, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl alkyl ether. Water-soluble polymers such as partially saponified polyvinyl acetate; sparingly water-soluble inorganic salts such as barium sulfate, calcium sulfate, magnesium carbonate, and calcium phosphate.

The particles obtained by the above-mentioned seed polymerization are washed according to a conventional method, and then large particles are removed by a method such as a wet classification method, and used as a spacer for a liquid crystal display device of the present invention.

The liquid crystal display device using the spacer for a liquid crystal display device of the present invention is excellent in compression resistance and does not cause display failure even when a load is applied for a long time.
Suitable for mobile phones and mobile devices. A liquid crystal display element using the spacer for a liquid crystal display element of the present invention is also one aspect of the present invention.

[0037]

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

Example 1 86 parts by weight of ion-exchanged water,
10 parts by weight of styrene, 2.5 parts by weight of octyl mercaptan and 0.02 part by weight of sodium chloride were weighed and put into a separable flask. A cooling tube, a stirring blade, and a nitrogen introducing tube were attached to this separable flask, and nitrogen was flown in for 30 minutes to perform nitrogen replacement. After that, the temperature was raised to 70 ° C. while rotating the stirring blade, nitrogen substitution was further performed for 1 hour, and then a solution prepared by dissolving 0.1 part by weight of potassium persulfate in 5 parts by weight of ion-exchanged water was charged using a syringe. did. The reaction was carried out at 70 ° C. for 24 hours, then cooled to room temperature to stop the reaction. The obtained reaction product was subjected to solid-liquid separation by centrifugation, ethanol was added to the solid component to wash the solid component, and then solid-liquid separation was performed again by centrifugation. After this washing operation was performed once again, seed particles A were obtained by further washing twice with ion-exchanged water. The average particle size of the obtained seed particles A is 0.71 μm,
The CV value was 5.0%.

To 4 parts by weight of the obtained seed particles A, 600 parts by weight of ion-exchanged water and 2 parts by weight of sodium lauryl sulfate were added and uniformly dispersed to obtain a seed particle dispersion liquid.
On the other hand, as a monomer to be absorbed by the seed particles A, 250 parts by weight of divinylbenzene, 50 parts by weight of iriamyl acetate, t-butyl peroxybenzoate (Perbutyl Z manufactured by NOF CORPORATION, 10-hour half-life temperature 104.3 ° C.) )
10 parts by weight, 1500 parts by weight of deionized water, and 4 parts by weight of sodium lauryl sulfate were added, and ultrasonication was performed to obtain an emulsion. The obtained emulsion was added to the seed particle dispersion liquid to form a mixed dispersion liquid, and the mixture was stirred at 35 ° C. for 4 hours, whereby the monomer was completely absorbed by the seed particles A.

A 5% aqueous solution of polyvinyl alcohol (GH-20, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added to the mixed dispersion 8
After adding 00 parts by weight, while stirring in a pressure resistant polymerization vessel,
Polymerization was performed at 120 ° C. for 8 hours, the obtained solid component was washed, and then large particles were removed to obtain particles. The average particle size of the particles was 3.2 μm, and the CV value was 2.9%. In addition, when the particle size distribution was examined, the amount of large particles having a particle size of 1.26 times or more the average particle size was 0 ppm.
Further, by using an ultra-micro hardness test system (Fisherscope H-100) manufactured by Fisher Instruments, a load of 17 mN is applied to any one particle at a load load speed of 0.28 mN / S, and the load is applied for 30 seconds. When the indenter movement amount ΔL was measured during the load holding time when it was held, ΔL was 0.058 μm. The ΔL / R of the particles was 0.018.

Next, a compression resistance test of a liquid crystal display device using the particles as a spacer for a liquid crystal display device was conducted by the following method. A pair of transparent glass plates (150 mm x 15
0 mm), a SiO ₂ film is deposited on one surface by the CVD method, and then the entire surface of the SiO ₂ film is sputtered by I
A TO film was formed to obtain a glass substrate with ITO. This I
A polyimide alignment film (SE-7210 manufactured by Nissan Chemical Industries, Ltd.) is arranged on a glass substrate with TO by spin coating.
After baking at 280 ° C. for 90 minutes, rubbing treatment was performed.
Next, the particles are dry-sprayed (D
ISm-μR) 100-200 per 1 mm ²
The cells were sprayed into individual pieces, arranged facing each other so that the rubbing direction was 90 °, and treated at 160 ° C. for 90 minutes to cure the sealing agent to prepare empty cells. In the obtained empty cell, T
After injecting N-type liquid crystal (MLC-6222 manufactured by Merck & Co., Inc.), the injection port was closed with an adhesive to manufacture a liquid crystal display element, and further heat treatment was performed at 120 ° C. for 30 minutes. A metal rod having a cross section of 7 mm × 7 mm was used to apply a load of 170 N to the liquid crystal display element thus obtained, and then sandwiched with a light-retaining film arranged in crossed Nicols so as to be in a normally white display mode. When the display unevenness was visually observed while applying a voltage of 7 V, no display unevenness was observed.

Example 2 To 72 parts of polyvinylpyrrolidone having a molecular weight of 40,000 and 2 parts of aerosol OT (anionic surfactant manufactured by Wako Pure Chemical Industries, Ltd.), 60 parts of styrene and 360 parts of ethanol were added and homogenized. Mixed in. To this solution, 1.0 part of azoisobutyronitrile was added, the temperature was raised to 65 ° C. under a nitrogen stream, and the reaction was continued for 30 hours to obtain seed particles B. The seed particles B had an average particle diameter of 1.3 μm and a CV value of 2.1%.

Ion-exchanged water 60 was added to 4 parts by weight of seed particles B.
0 part by weight and 2 parts by weight of sodium lauryl sulfate were added and uniformly dispersed to obtain a seed particle dispersion liquid. On the other hand, divinylbenzene 250 is used as a monomer to be absorbed by the seed particles B.
50 parts by weight of isoamyl acetate, 10 parts by weight of t-butylperoxybenzoate, and 1 part of deionized water.
500 parts by weight and 4 parts by weight of sodium lauryl sulfate were added, and ultrasonication was performed to obtain an emulsion. The emulsion was added to the seed particle dispersion liquid to prepare a mixed dispersion liquid, and the mixture was stirred at 35 ° C. for 4 hours, whereby the monomer was completely absorbed by the seed particles B.

A 5% aqueous solution of polyvinyl alcohol (GH-20, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added to the mixed dispersion.
After adding 00 parts by weight, while stirring in a pressure resistant polymerization vessel,
Polymerization was performed at 120 ° C. for 8 hours, the obtained solid component was washed and large particles were removed to obtain particles. The average particle size of the particles was 5.3 μm, and the CV value was 2.9%. In addition, when the particle size distribution was examined, the amount of large particles having a particle size of 1.26 times or more the average particle size was 0 ppm. Further, when ΔL and ΔL / R were measured in the same manner as in Example 1,
ΔL was 0.100 μm, and ΔL / R was 0.019. Further, a liquid crystal display element using the particles as a spacer for a liquid crystal display element was subjected to a compression resistance test in the same manner as in Example 1, and no display unevenness was observed in the liquid crystal display element.

Comparative Example 1 10 parts by weight of benzoyl peroxide (manufactured by NOF CORPORATION, NIVER BW, 10-hour half-life temperature 73.6 ° C.) was used in place of t-butyl peroxybenzoate, and the polymerization temperature was 90 ° C. Particles having an average particle size of 3.3 μm, a CV value of 2.8% and a particle size of 1.26 times or more the average particle size and a mixing amount of 0 ppm as in Example 1 except that Got When ΔL and ΔL / R of this particle were measured in the same manner as in Example 1, ΔL was 0.104 μm and ΔL / R was 0.032. Further, a liquid crystal display device using the particles as a spacer for a liquid crystal display device was subjected to a compression resistance test in the same manner as in Example 1. As a result, noticeable display unevenness was observed in the liquid crystal display device.

Comparative Example 2 10 parts by weight of benzoyl peroxide (manufactured by NOF CORPORATION, NIVER BW, 10 hour half-life temperature 73.6 ° C.) was used in place of t-butyl peroxybenzoate, and the polymerization temperature was 90 ° C. Except that the average particle size was 5.1 μm, the CV value was 2.4%, and the amount of large particles having a particle size of 1.26 times or more the average particle size was 0 ppm. Obtained. When ΔL and ΔL / R of this particle were measured in the same manner as in Example 1, ΔL was 0.133 μm and ΔL / R was 0.026. Further, a liquid crystal display device using the particles as a spacer for a liquid crystal display device was subjected to a compression resistance test in the same manner as in Example 1. As a result, noticeable display unevenness was observed in the liquid crystal display device.

(Comparative Example 3) 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (manufactured by NOF CORPORATION) in place of t-butylperoxybenzoate
Perocta O, 10 hour half-life temperature 66.3 ° C.) 10 parts by weight were used, and the average particle size was 5.2 μm and the CV value was 2.6% in the same manner as in Example 2 except that the polymerization temperature was 90 ° C.
Particles having a mixed amount of 0 ppm of large particles having a particle size of 1.26 times or more the average particle size were obtained. About this particle Example 1
When ΔL and ΔL / R were measured in the same manner as
Was 0.128 μm and ΔL / R was 0.025. Further, a liquid crystal display device using the particles as a spacer for a liquid crystal display device was subjected to a compression resistance test in the same manner as in Example 1. As a result, noticeable display unevenness was observed in the liquid crystal display device.

(Comparative Example 4) 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (manufactured by NOF CORPORATION) in place of t-butylperoxybenzoate
Perocta O, 10-hour half-life temperature 65.3 ° C.) 6 parts by weight were used, and the average particle size was 6.2 μm and the CV value was 2.6% in the same manner as in Example 2 except that the polymerization temperature was 90 ° C. Particles having a mixed amount of large particles having a particle diameter of 1.26 times or more the average particle diameter of 5 ppm were obtained. When ΔL and ΔL / R of this particle were measured in the same manner as in Example 1, ΔL was 0.128 μm and ΔL / R was 0.025. Further, a liquid crystal display device using the particles as a spacer for a liquid crystal display device was subjected to a compression resistance test in the same manner as in Example 1. As a result, noticeable display unevenness was observed in the liquid crystal display device. Further, when the compression load site was observed, the breakage of the spacer was observed. The results of Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Table 1.

[0049]

[Table 1]

[0050]

According to the present invention, there is provided a spacer for a liquid crystal display element, which has a small amount of plastic deformation while retaining a compressive load, an excellent particle size distribution, and a small amount of large particles mixed therein, and a liquid crystal display element using the spacer. can do.

Claims (3)

[Claims] 1. An indenter movement amount ΔL during load holding time when a load of 17 mN is applied to any one particle at a load speed of 0.28 mN / s and the load is held for 30 seconds, and the particle size of the particle. A liquid crystal having a ratio (ΔL / R) to the diameter R of 0.02 or less, and a mixing amount of particles having a particle diameter of 1.26 times or more the average particle diameter of 1 ppm or less. Spacer for display element. 2. The spacer for a liquid crystal display element according to claim 1, wherein the average particle diameter is 1 to 20 μm, and the CV value represented by the following formula is 3% or less. CV (%) = average particle size (μm) / standard deviation (μm) × 1
00 3. A liquid crystal display element comprising the spacer for liquid crystal display element according to claim 1 or 2.