JPS6195016A - Spacer - Google Patents

Abstract

PURPOSE:A spacer having particle diameters with high uniformity, improved reliability of liquid crystal display device, etc., comprising polymer particles obtained by making seed polymer particles dispersed in an aqueous dispersing medium absorb a lipophilic substance, absorb a monomer, and polymerizing it with an oil-soluble polymerization initiator. CONSTITUTION:Seed polymer particles (e.g., polystyrene, etc.) having particle diameters with high uniformity is dispersed into water to give an aqueous dispersion, a lipophilic substance (e.g., 1-chlorododecane, etc.) is emulsified and dispersed into water with soap, etc., and is added to the aqueous dispersion. A monomer (e.g., stylene, etc.) is absorbed in the seed polymer particles, incorporated with an oil-soluble polymerization initiator (e.g., azobisisobutyronitrile, etc.), and, if necessary, a polymerization adjustor (e.g., carbon tetrachloride, etc.), a water-soluble polymerization inhibitor (e.g., hydroquinone, etc.) and a polymerization reaction is done to give the aimed polymer particles. EFFECT:A liquid crystal display device keeping thickness of liquid crystal layer in high accuracy uniformly, having high reliability and improved durability, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spacer used to define a gap of about 0.5 to 100 μm.

In particular, the present invention relates to a spacer that defines the distance between electrodes in a liquid crystal display device, or a spacer that functions as a support material for microcapsules containing a coloring agent in pressure-sensitive copying paper.

[Prior Art] Generally, in a liquid crystal display device, liquid crystal is sealed between two electrodes, at least one of which is made of a transparent material. A spacer is interposed between the electrodes to define a distance between the electrodes. Conventionally, such a spacer is a spherical material such as glass fiber or a resin such as glass, silica, or polystyrene, which has a diameter corresponding to the thickness of the liquid crystal layer.

However, when using glass fiber as a spacer, ##! It is difficult to avoid a situation where some of the fibers become entangled or overlap, and it is difficult to define a predetermined gap with high precision.

Furthermore, when the above-mentioned spherical substances are used as spacers, it is difficult to make the particle size of these spherical substances uniform;
Therefore, it has been difficult to define a predetermined gap with high precision.

In a liquid crystal display device, if the thickness of the liquid crystal layer is non-uniform, (1) interference colors may differ locally, so-called color unevenness, and (2) the electric field strength applied to the liquid crystal layer may be non-uniform. As a result, the contrast ratio is not uniform,
(c) Since the response speed is proportional to the square of the thickness of the liquid crystal layer, problems arise such as the response speed not being uniform, so the spacer is required to have high precision.

On the other hand, pressure-sensitive copying paper called carbonless copying paper includes, for example, a color former layer containing microcapsules containing a color former (hereinafter also referred to as "color former microcapsules") and a color developer layer. A type in which an egg coloring agent layer is formed on the back and front surfaces of two stacked supports (usually paper), or a color former microcapsule and a color developer are formed on the front side of a lower support. Types in which a recording layer is formed by mixing or laminating these are known.

In such pressure-sensitive copying paper, when mechanical or impact pressure is applied to the surface of the upper support by a writing instrument, typewriter, or various other mechanical printers, the microcapsules containing the coloring agent are released. When the capsule is destroyed, the color forming agent inside the capsule is exposed and comes into contact with the color developing agent, thereby developing color and achieving copy recording.

By the way, in this type of conventional pressure-sensitive copying paper, so-called "color-forming fog" occurs when color-forming agent microcapsules are destroyed by unexpected mechanical pressure applied during handling other than during manufacturing, storage, etc. ” is likely to occur. As a technique to solve such problems, as disclosed in Japanese Patent Application Laid-Open No. 54-68307, a recording layer consisting of color former microcapsules and a color developer contains a plastic pigment. Pressure-sensitive recording paper is known, but even with this pressure-sensitive recording paper, sufficiently satisfactory results have not been obtained.

[Problems to be Solved by the Invention] The present invention has been made against the above background, and its purpose is to improve the accuracy of spacers,
The object of the present invention is to provide a spacer that can define a minute gap or space of about 100 μm with high accuracy.

More specifically, an object of the present invention is to provide a spacer that can maintain a uniform thickness of a liquid crystal layer with high precision and form a highly reliable and durable liquid crystal display device. It is in. −.

Furthermore, another object of the present invention is to suppress the occurrence of colored capri due to the accidental destruction of color former microcapsules, and to form a small pressure-sensitive copying paper which is excellent in color development and does not deteriorate over time. Another object of the present invention is to provide a spacer that functions as a protective agent for color former microcapsules.

[Means for Solving the Problems] The spacer of the present invention is characterized by absorbing a lipophilic substance into the rod polymer particles dispersed in an aqueous dispersion medium, and then absorbing a monomer therein. It is different from the polymer particles obtained by polymerization.

The present invention will be explained in detail below.

In the spacer of the present invention, in an aqueous dispersion prepared by dispersing seed polymer particles having a highly uniform particle size in water, the nuclide polymer particles have a solubility in water of 10.
The absorption capacity of the monomer is increased by swelling the seed polymer particles by absorbing a lipophilic substance of less than 'lj/l, and then adding the monomer into the system and further absorbing it into the seed polymer particles at a temperature of 40°C. ~100℃
, preferably spherical polymer particles obtained by polymerization under conditions of 60 to 90°C.

The average particle size of the polymer particles thus obtained can be estimated by the following formula.

The particle size of the polymer particles can be controlled by selecting the particle size of the seed polymer particles, and can be increased by repeating the same process using the polymer particles obtained by the above process as the seed polymer particles. It is possible to form polymer particles with a diameter of approximately 100
A spacer having a desired particle size can be obtained within a range of .mu.m or less, usually within a range of about O,S to 30 .mu.m. Further, since the polymer particles have a particle size distribution corresponding to that of the seed polymer particles, it is necessary to use seed polymer particles with a narrow particle size distribution in order to obtain a spacer with a uniform particle size.

The ridge polymer particles used for manufacturing the spacer are not particularly limited as long as they can be swollen with the lipophilic substance used in the present invention, and may be ordinary polymer latex, polymer emulsion, or polymer dispersion. Specifically, polystyrene made by emulsion polymerization, styrene/-butadiene copolymer, carboxyl-modified styrene-butadiene copolymer, acrylic polymer, acrylic copolymer, polybutadiene, vinyl acetate polymer,
Examples include vinyl chloride polymers.

As mentioned above, it is necessary to use seed polymer particles having a uniform particle size, and in order to obtain such seed polymer particles, for example, A, R, Goodal 1eta1.
J, Polym, Sci, Po1m Chem Edi
tionvol15. The technique disclosed in J. P., 2193 (1977) can be used.

The lipophilic substance used in the manufacture of the spacer has a solubility in water of l·Og/! Hereinafter, preferably xo”li/l
The following substances, with a molecular weight of 5000 or less, preferably 5
00 or less, and specific examples thereof include 1-chlordodecane, dioctyl adipate, n-hexane, and the like. Dioctanoyl peroxide, uroylpe!reoquinde, etc. can also be used as lipophilic substances, and when these are used, they can also function as a polymerization initiator.

Although there are no particular limitations on the method for absorbing the lipophilic substance into the seed polymer particles, the lipophilic substance is usually emulsified and dispersed in water using soap or the like and then added to the water containing the seed polymer particles. At this time, it is also possible to add a water-soluble solvent such as acetone to promote the transfer of the lipophilic substance to the glazed polymer particles.

There are no particular limitations on the seven polymers used in the production of spacers as long as they can undergo radical polymerization. Specific examples of monomers include aromatic monomers such as styrene, α-methidistyrene, p-methidistyrene, halogenated styrene, divinylbenzene, and 4-vinypyridine, vinyl diesters such as acetic acid and vinyl propionate, and vinyl propionate. ,.

Unsaturated nitriles such as acrylonitrile, methidiacrylate, methidimethacrylate, ethyl acrylate,
Ethyl methacrylate, butyl acrylate, butydimethacrylate, 2-ethysehexyleacrylate, 2-
Ethyl νhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, N,
Examples include ethylenically unsaturated carboxylic acid esters such as N-dimethycyaminoethyl methacrylate.

Conjugated diolefins such as mata, butadiene, isoprene, etc. can also be used.

In addition, acrylamide, methacrylamide, glycidyl acrylate, glycidifre methacrylate, N
-Methyloacrylamide, N-methylo-! Dimethacrylamide, 2-hydroquine, ethyl acrylate, 2
-Hydroquine ethyl methacrylate, etc., Diary I7
Tallate, allyl acrylate, allyl methacrylate, etc. can also be used depending on the purpose. Acrylic acid, methacrylic acid, itaconic acid, and fumaric acid can also be used in proportions that do not inhibit swelling polymerization, if necessary.

In addition, when a difunctional vinylene monomer such as divinylbenzene, ethylene glycol diacrylate, or ethylene glycol dimethacrylate is used in an amount of 2 to 70% by weight, preferably 5 to 50% by weight based on the total monomer, the hardness of the resulting polymer particles increases. becomes high, and the durability as a spacer improves.

If the amount of the difunctional vinyl monomer is too large, the particles will shrink significantly during polymerization, resulting in distorted particle shapes.
Therefore, it is not preferable as a spacer.

The amount of Mosomashi used is not particularly limited as long as it can be absorbed by the seed polymer particles, but in terms of absorption capacity,
It is 200 times or less, preferably 100 times or less relative to the weight of the seed polymer particles.

In the production of spacers, a small amount of emulsifier may be added when adding monomers to the reaction system or during polymerization in order to increase the stability of the resulting particles after polymerization. In that case, the amount of emulsifier added is at most below the critical micelle formation concentration (C, M, C) at the in-water melting point during polymerization. Above this concentration, small-sized polymer particles are generated during polymerization,
It becomes difficult to obtain homogeneous polymer particles.

The polymerization initiator used in the production of the spacer is an oil-soluble polymerization initiator, such as azohisisobutylnidrya, benzoylbeyaoxide, 2,4-dichlorol-lebenzoylberoquinde, diocta)-d/l. /peroxide, di-3.5.5-)rimethylrehexanoyl peroxide, lawaloyl peroxide, etc., which may be used alone or in combination. The oil-soluble polymerization initiator is usually dissolved in a monomer or Aishi φ poison solvent beforehand and added to the polymerization system.

In the present invention, if a water-soluble polymerization initiator such as hydrogen peroxide or potassium persulfate is used, a large amount of small-sized polymer particles will be generated, making it impossible to obtain homogeneous polymer particles.

Further, during polymerization, a polymerization regulator such as carbon tetrachloride or t-dodecylmercaptan, or a water-soluble polymerization inhibitor such as hydroquinone or N,N-diethylhydroxylamine may be added. The presence of a water-soluble polymerization inhibitor is effective in suppressing the generation of small-sized polymer particles. Furthermore, during polymerization, commonly used suspension protectants, such as polyvinifleacicol, polyvinylpyrrolidone, gelatin, carboxymethylcellulose, magnesium phosphate, barium carbonate, etc., can be added.

For the spacer of the present invention, it is necessary to set an allowable range of the glass transition temperature of the polymer constituting the spacer depending on the purpose of use. For example, when used at room temperature, the glass transition temperature of the polymer is 50%. ℃ or higher is required. .

Furthermore, the spacer of the present invention can be coated or chemically treated on the surface of the particles according to the state of use or purpose of use.
1.

Next, a case will be described in which the above-described spacer of the present invention is used as a spacer for a liquid crystal display device.

FIG. 1 is an explanatory cross-sectional view schematically showing a liquid crystal display device. In this example, a transparent conductive film 21 made of, for example, tin oxide, indium oxide, etc. is coated on the surfaces of non-conductive transparent plates 11 and 12 made of, for example, glass or synthetic resin.
and 22 are vapor-deposited or coated so as to have a predetermined shape according to the display pattern.
A spacer 3 is interposed between the electrode plates El and E2 to define a constant distance between the electrode plates El and E2. Furthermore, a space partitioned by electrode plates E1 and E2 is cooled by a cooling material 4 made of epoxy resin or the like, and liquid crystal is sealed inside to form a liquid crystal layer 5.

The spacer 3 has a grain size corresponding to the thickness of the liquid crystal layer 5 to be defined, and is usually in the range of about 2 to 50 μm, and its standard deviation value is preferably within 10 inches of the grain size.

Next, the case where the above-described spacer of the present invention is used as a coating composition for pressure-sensitive copying paper will be described.

The spacer of the present invention is mixed with a color former and applied to a support such as paper to form pressure-sensitive copying paper. Such pressure-sensitive copying paper is produced by applying a color former composition containing color former microcapsules and the spacer of the present invention and a color developer composition to the surface of a support in a laminated state to form a color former layer and a color developer composition. A coating composition formed by mixing the color former composition and a color developer composition was applied to the surface of the support to form a single coating layer. It also includes those in which a color forming agent layer and a color developing agent layer are formed on the surfaces of different supports and stacked so that the two layers are in contact with each other.

The particle size of the spacer used for pressure-sensitive paper is 1 to 30μ.
It is desirable that the standard deviation value is within 20% of the particle size.

In addition, the amount of spacer used is
It is desirable that the amount is 5 to 200]ti parts based on L/lOO parts by weight.

The coloring agent constituting the coloring agent microcapsules is not particularly limited, and commonly used coloring agents can be used. As a coloring agent, for example, 3,3-bis(p
-dimethylaminophenyl)-6-dimethyaamino7thalide (so-called crista, rL/violet lactone), triaryamethane compounds such as 3,3-bis(p-dimethylaminophenyl)phthalide, 4,4'-bis-dimethyl Diphenymethane compounds such as aminobenzhydrin benjaether, xanthine compounds such as rhodamine-B-anilinolactam, rhodamine-(p-nitroanilino)lactam, 7-dimethylamino-2-methoxy7-silane, and thiazines such as benzoyalucomethylene blue Examples include spiro-based compounds such as 3-methycyspirodinaphthopyran and the like.

These color formers can be used alone or in combination of two or more.

Microcapsules containing a coloring agent can be prepared using commonly used methods such as coacervation method, interfacial polymerization method, 1n
- It can be formed by an in-situ polymerization method or the like.

Further, the color developer is not particularly limited, and commonly used ones can be used.

Examples of color developers include inorganic color developers such as acid clay, activated clay, bentonite, and zeolite, phenolic resins,
Examples include organic color developers such as salicylic acid salt conductors.

[Examples] Examples of the present invention will be described below, but the present invention is not limited thereto. Note that "parts" represent parts by weight.

Example 1 Styrene-butadiene latex A obtained by ordinary emulsion polymerization (styrene/butadiene = 50750, average particle size)
Diameter: 0.22 μm, 1 grain, this? -) standard deviation value 0.0
2μm 1'solid content 21.5%') IIl (as solids), 2fI of 1-chloryadodecane and 0.15% of lawaryl sodium sulfate. li+, water 10Ii and acetone 31
An emulsion obtained by stirring the mixture with a homogenizer was added thereto, and the mixture was stirred for 12 hours to allow Latex A to absorb dodecane mouth-to-mouth over an overnight period. To this, a mixture of 1.9 t of azobisisobutyronitrile dissolved in styrene 90I and dipinylbenzene OI and 150I of water were added, and the mixture was stirred for 30 minutes to allow latex A to absorb the monomer and azobisisobutyronitrile. Polymerization was carried out at 70° C. for 12 hours. The polymerization conversion rate was 95.4, and the average particle size was 1. Latex B was obtained which consisted of particles having a spherical shape with a standard deviation value of 0.10 μm and a substantially uniform particle size.

The polymer particles obtained from this latex B will be referred to as "spacer I".

Example 2 To the latex Bl, 9 (in terms of solid content) obtained in Example 1, 2 I (dioctanoylperoxy) was added to 10 ml of water.
11. Sodium lauryl sulfate 0.15. il.

An emulsion obtained by emulsifying an acetone 3I solution using a homogenizer was added and stirred for 12 hours to absorb the dioctanoyl peroxide into the seed polymer particles.

Next, add 87g of styrene to the system and add ethylene glycol! 10 g of resin methacrylate, 3I methacrylic acid, 10 pt of polyvinyl urecol, and 400 It of dissolved water were added, and polymerization was carried out at a temperature of 75° C. for 20 hours to obtain Latex C.

This latex C has a polymerization conversion rate of 96 cm and an average particle size of 4
．． Spherical shape with a standard deviation value of 0.50 μm for a particle size of 5 μm.

It was confirmed that the particles were composed of polymer particles with almost uniform particle size.

The polymer particles obtained from this latex C will be referred to as "spacer 2."

Example 3 Latex C instead of latex B in Example 2
Latex D was obtained in the same manner as in Example 2 except that .

This latex D has a polymerization conversion rate of 95% and an average particle size of 2.
It was confirmed that the polymer particles were almost perfectly spherical and had a uniform diameter with a standard deviation value of 2.3 μm per particle size of 0.0 μm.

The polymer particles obtained from this latex D will be referred to as "Spacer 3."

In addition, the following three types of spacers were prepared for comparison.

(1) Average particle size obtained by ordinary suspension polymerization: 1.
Polystyrene particles with a standard deviation of 0.7 μm and a particle diameter of 7 μm are referred to as “Comparative Spacer 1”.

(2) Obtained by ordinary suspension polymerization, average particle size 5.
Bo17 styrene particles with a standard deviation value of 2.11° C.m for a particle diameter of 2 μm are designated as “Comparative Spacer 2”.

(3) A columnar body formed by cutting glass fiber with a diameter of 7 μm into a length of 2 mm is referred to as “Comparative Spacer 3”.

(Application to Liquid Crystal Display Device) Using each of the above spacers 1 to 3, a 39i liquid crystal display device having the configuration shown in FIG. 1 was formed. Note that indium oxide was used as the transparent conductive film in the liquid crystal display device, and phenyl nematic liquid crystal was used as the liquid crystal material.

It was confirmed that in all such liquid crystal display devices, the interference color was uniform, and the liquid crystal layer was defined to have a uniform thickness with high precision.

Further, for comparison, when similar liquid crystal display devices were formed using each of Comparative Spacers 1 to 3, all of these devices had partially different interference colors and color unevenness occurred.

(Application to pressure-sensitive copying paper) Color former microcapsules prepared by the method described below, 20 parts of wheat starch particles, 50 parts of a 20% by weight starch aqueous solution
Three types of color former compositions were prepared by mixing 10 parts of an aqueous dispersion containing 45% by weight of each of spacers 1 to 3 as a solid content.

The color former microcapsules were prepared as follows.

Dissolve 5 parts of crystal violet lactone in 50 parts of phenylquinlylethane and add this to an aqueous solution consisting of 10 parts of gum arabic and 60 parts of warm water at 40°C to form 2 to 2 oil droplets.
A 3 μm aqueous emma I rejo/ was prepared. Next, isoelectric point 7
．． Add 10 parts of acid-treated gelatin containing 8% to 40°C warm water.
50% acetic acid was added under constant stirring to adjust the pH to 4.2. Then,
Coaselevation was induced by adding 250 parts of K4 warm water at 40°C. At this time, a thick liquid film of gelatin and gum arabic was formed around the oil droplets in which the color former was dissolved. Next, in order to gel the thick liquid film,
The mixture was cooled to .degree. C., and 4 parts of a 37-mer formaldehyde aqueous solution was added to harden the wall film.

Here, 40 parts of a 10% sodium hydram salt aqueous solution of carboxymethylseV-lose was added, and 1
An aqueous solution of sodium hydroxide was added dropwise to raise the pH to 9.5, and the temperature of the solution was further raised to 50°C.

A color developer composition was prepared by mixing 10 parts of fine particles of phenol-hydramayadehyde resin, 30 parts of kaolin clay, and 5 parts of styrene-getadiene copolymer latex.

Next, the color former composition was coated with an air knife on the surface of a base paper having a basis weight of 401/m 2 to a solid content of 5.
It was coated in an amount of 9 parts m2 and dried. Further, the color developer composition was coated on the coating layer of the color former composition by air knife coating so that the solid content was 61 parts m2, and dried to produce a total of three types of pressure-sensitive copying papers.

When the degree of color development fog during coating on each of these pressure-sensitive copying papers was measured using a reflection densitometer, the reflectance of the coating layer surface was 98.0, 98.5, and 98.0, respectively. There was no color fogging at all.

In addition, in order to investigate color fogging during stacking and storage of this pressure-sensitive copying paper, a uniform stacking pressure of 5001/crrt2 was applied to the copying paper, and after 240 hours, the reflectance of the coated layer surface was measured. The measurements were 9 each.
6.0%, 95.0%, and 94.5%, and no color fogging due to stacking pressure was observed.

It was also found that the pressure-sensitive copying paper has good abrasion resistance and sufficiently high color density due to writing pressure and typing pressure, and has excellent quality as a pressure-sensitive copying paper.

For comparison, pressure-sensitive copying paper obtained in the same manner as described above except that the spacer of the present invention was not used, and Comparative Spacer 1.2 were used instead of the spacer of the present invention, and For each pressure-sensitive copying paper obtained in the same manner as in the above method, the occurrence of color fog was examined in the same manner as in the above method.

As a result, the color fog during coating was hardly observed, as the reflectance of the coating layer surface was 95.0%, 93.0%, and 92.0%, respectively, but the coloration during stacking was not observed. Regarding fog, the reflectance of the paint layer surface is 73.0 and 82, respectively.
．． 5, 80.5%, and almost the entire surface of the coating layer was colored blue.

[Effects of the Invention] As is clear from the description of the examples, the spacer of the present invention emulsifies a monomer by absorbing it into seed polymer particles whose average particle size and particle size distribution are selected depending on the use of the spacer. Since they are spherical polymer particles formed by polymerization or suspension polymerization and have a strictly defined uniform particle size, spacers that define a certain gap or space in the range of about 0.5 to 100 μm are used. It is extremely practical.

When the spacer of the present invention is used as a spacer for a liquid crystal display device, since the spacer has a strictly defined uniform particle size, it becomes possible to define the thickness of the liquid crystal layer with high precision, and the thickness of the liquid crystal layer can be defined with high precision. Improved reliability and durability can be achieved.

When the spacer of the present invention is mixed with the color former microcapsules and used as a coating composition for pressure-sensitive copying paper, the color former microcapsules may be mixed with the pressure-sensitive copying paper during storage, transportation, etc. It is possible to suppress the destruction caused by unexpected mechanical pressure applied to the surface, and to extremely effectively prevent the occurrence of colored capri. The reason why such an effect is produced is not necessarily clear, but by using a spacer with a highly uniform particle size mixed with color former microcapsules, the coating layer containing the color former microcapsule can be improved. It is possible to achieve a state in which each component particle is extremely homogeneously dispersed, and since the coloring agent microcapsules exist in the gaps between the spacers with high mechanical strength, a large amount of pressure is applied directly to the microcapsules. This is thought to be due to the fact that the effects of

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view schematically showing a liquid crystal display device. 11.12... Non-conductive transparent plate 21.22... Transparent conductive film El, E2... Electrode plate 3... Spacer 4... Hole material 5
...Liquid crystal layer

Claims (1)

[Claims] 1) A spacer comprising polymer particles obtained by absorbing a lipophilic substance into seed polymer particles dispersed in an aqueous dispersion medium, then absorbing a monomer, and polymerizing the seed polymer particles with an oil-soluble polymerization initiator.