JPS62278535A - Powder composition - Google Patents

Abstract

PURPOSE:To distribute respective particles to a specified ratio and to decrease uneven spraying by using a mixture composed of epoxy spherical particles which contain a latent curing agent compatibly in the particles and are partially cured by an amine compd. and silica spherical particles. CONSTITUTION:The epoxy compd. contg. >=2 epoxy groups in the molecule is added to the latent curing agent. The amt. of the curing agent is usually specified to 0.05-1 equiv. per epoxy equiv. of an epoxy compd. and the epoxy compd. is partially cured by the amine curing agent to a spherical particle state. The epoxy spherical particles act as an adhesive component and are formed to have <=50mum average particle and <=100% fluctuation rate of the particle size. The silica spherical particles act as a spacer component and are formed to have <=10mum average particle size and 20% fluctuation rate of the particle size. The mixing ratio of the epoxy and silica spherical particles is in the range of about 0.01-100 pieces epoxy spherical particles per piece of the silica spherical particles when counted as the number of the particles within + or -20% of the average particle size.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a powder composition for a spacer before an adhesive for a liquid crystal electro-optical element (liquid crystal display device).

[Prior Art] Generally, only spacer particles are used in liquid crystal electro-optical elements, but adhesive particles are also being used together with the demand for larger screens.

However, due to the state of the art, the optimal combination of spacer particles and adhesive particles is not yet known.

[Problems to be Solved by the Invention] The conventional technique of separately dispersing spacer particles and adhesive particles has the disadvantage that the distribution ratio of the two tends to be uneven. Furthermore, it is not easy to detect uneven distribution when it occurs.

An object of the present invention is to provide a technique that can always keep the microscopic distribution ratio of spacer particles and adhesive particles constant and reduce uneven distribution.

[Means for solving problems] In order to achieve the above object, the present invention consists of the following configuration.

"A powder composition comprising a mixture of epoxy-based spherical particles and silica-based spherical particles that contain a latent curing agent in a compatible manner inside the particles and are partially cured with an amine compound." The details of the invention will be sequentially explained below.

Epoxy-based spherical particles containing a latent curing agent compatibly inside the particles and partially hardened with an amine compound can be produced as follows.

The epoxy compound used in the present invention is preferably one containing two or more epoxy groups in the molecule. Examples include bisphenol A-type glycidyl ethers at both ends, diglycidyl ethers of polyethylene glycol, polyglycidyl ethers of phenol novolak-type compounds, N, N, N", N"-te1-laglycidyl m-xylene. Diamines are used alone or in combination. If necessary, it is also possible to use a compound having one epoxy group in the molecule, such as 2-ethylhexyl glycidyl ether.

Before forming the above-mentioned epoxy compound into fine spherical particles, a latent curing agent is added to the epoxy compound. The latent curing agent used here is preferably a curing agent that exhibits a pot life of one day or more at room temperature in an optimal mixing ratio composition (composition with the fastest curing rate) with bisphenol A tucuricidyl ether.

Examples of such curing agents include dicyandiamide,
imidazoles, Lewis acid complexes, phenols, phenol novolaks, polyvinylphenols, carboxylic acids, acid anhydrides, acidic polyesters,
Examples include carboxyl group-containing polymers such as styrene-maleic acid copolymers, polyamines, and modified polyamines.

Among these, preferred latent curing agents are polycondensation type compounds, and phenolic curing agents such as phenol novolacs, polyvinylphenols, and polybisphenol A are particularly suitable. The epoxy compound and the latent curing agent are preferably used in combination when they exhibit at least partial compatibility, preferably complete compatibility.

In order to make the epoxy compound and the latent curing agent compatible, the epoxy compound and the latent curing agent can be mixed by heating or dissolved in a common solvent for both, and if necessary, the solvent can be removed by drying under reduced pressure or the like.

The amount of latent curing agent to be used is usually preferably 0.05 to 1 equivalent per equivalent of the epoxy group of the epoxy compound, but it is preferable to partially cure the latent curing agent with an amine curing agent to form spherical particles as described in (2) below. Therefore, the optimal value may be found in a fairly small amount. In addition, when using a catalytic latent curing agent,
Approximately 20% or less of the weight of the epoxy compound is used.

When a latent curing agent is partially cured into particles with an amine-based curing agent, it is inevitable that it will be separated into islands from the epoxy compound as the degree of polymerization of the epoxy compound increases, but in all cases the separated state is fine. Therefore, curing by the latent curing agent is not significantly affected, and this state is defined as "compatible" here. The method of spheroidization will be described below.

A method such as dropping mechanically pulverized particles of a mixture of an epoxy compound and a latent hardener that are solid at around room temperature, or a mixture of an epoxy compound and a latent hardener that are partially hardened with a hardener, through a heating cylinder by gravity. There is a method to make it spherical (first
method).

Another method involves suspending a mixture of an epoxy compound and a latent curing agent in an aqueous liquid to form spheres (this is the second method).

Although there are no particular limitations on the first method and the second method, the second method is particularly preferred from the viewpoint of particle uniformity, sphericity, etc. Among these, a method of emulsification using a surfactant or the like is preferred in terms of productivity.

There are various methods for suspending the mixture of the second method epoxy compound and latent curing agent in an aqueous liquid.

Typical methods are listed below, but these methods are not particularly limited.

(2) A method of cutting the mixture or its solution into droplets by continuously discharging the mixture or its solution from a nozzle that moves in the air or in the liquid, and collecting the droplets in the liquid.

(2) A method in which the mixture or its solution is ejected in pulses from a nozzle in the air or in a liquid, and the mixture or its solution is collected in the liquid.

(2) A method of emulsifying using a combination of the mixture containing a surfactant and water.

■ A method of emulsifying using a combination of a powder emulsifier, the mixture, and water.

(2) A method of emulsifying using a combination of water containing a protective colloidal substance and the mixture.

Among the above methods, methods 1 to 2 are preferably used in the present invention from the viewpoint of productivity, but a rough combination of methods 1 to 2 is also preferably used.

What is important in the second method is to partially cure the mixture of the epoxy compound and the latent curing agent with an amine compound and to keep it in the state of solid spherical particles at least at room temperature. The amine curing agent and curing method for this purpose are not particularly limited; ■ A mixture of an epoxy compound and a latent curing agent to which a curing agent has been added is suspended in an aqueous liquid and partially cured as it is. There are two methods: (1) a method in which a water-soluble amine curing agent is added to an aqueous suspension of a mixture of an epoxy compound and a latent curing agent for partial curing;

Whichever method is used, in order to cure the suspended particles without bonding them to each other, it is preferable to cure at room temperature. agents often give favorable results.

A case in which a mixture of an epoxy compound and a latent curing agent is suspended in an aqueous liquid using a surfactant will be described below.

The kudzu surfactant used preferably has an HLBliIli of 10 or more. When the H2S value is lower than this, the stability of the emulsion is impaired and it tends to be difficult to obtain a good particulate cured product. Particularly suitable surfactants include ether-type nonionic surfactants such as polyoxyethylene/phenol-substituted ethers, polyoxyethylene/polyoxypropylene block polyethers, and higher fatty acid esters of polyethylene glycol. These include ester-type nonionic surfactants such as ethyl fatty acids of polyhydric alcohols, and alkoxylated rosins.

The amount of surfactant used is important. The above surfactant is
It is preferable that the amount is 2% by weight or more based on the mixture of the epoxy compound and the latent curing agent. When the amount of surfactant is less than this, the stability of the emulsion tends to decrease and it becomes difficult to obtain a good particulate cured product. The upper limit of the amount of surfactant used is not particularly limited, but it is generally preferably 30% by weight or less based on the mixture in order to prevent deterioration of the physical properties of the particles.

Generally, the difficulty of emulsifying a compound is affected by its viscosity. When the mixture has a high viscosity or is solid at room temperature, it is difficult to emulsify it sufficiently using mechanical force alone. In such cases, there is a method of using a diluent of an epoxy compound together with a surfactant, or of heating and liquefying the material.

Diluents include ketones, alcohols, cellosolves,
Examples include dioxane, aromatic hydrocarbons, and esters such as ethyl acetate.

Although the emulsification method is not particularly limited, typical methods are shown below.

The above-mentioned epoxy composition containing a surfactant is heated at room temperature, cooled or heated, and water is gradually added thereto while stirring at high speed.

The particles may contain other additives as long as they do not impair the present invention. The most typical additives are organic and solid pigments and dyes used for coloring purposes. These are usually added before the epoxy composition is suspended in an aqueous liquid, but it is also possible to dye the epoxy composition after it is formed into spherical particles.

The mixture of epoxy compound and latent curing agent suspended in an aqueous liquid is partially cured by adding an amine curing agent to the suspension in the aqueous liquid or before forming into suspended particles.

For this purpose, particularly favorable results are often obtained when the following amine curing agents are used.

The amine curing agent is an amine characterized by mixing a stoichiometrically calculated equivalent amount of amine with an epoxy compound at room temperature, and having a Shore A hardness of 50 or more after being left at room temperature for 8 hours. It is preferable to use a type compound.

If the Shore A hardness is smaller than this value, the curability of the suspended particles tends to decrease, making it difficult to obtain a good particulate cured product. Note that the normal temperature here refers to 20'C.

Examples of the curing agent that can be used in the present invention include the following compounds, but are not particularly limited thereto. Polyethylene polyamines such as piperazine, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, alcohol amines such as monoethanolamine, N(2-aminoethyl)piperazine, etc.

The curing method is particularly preferably achieved by adding to an aqueous liquid suspension an amine curing agent that satisfies the Shore A hardness conditions described above.

Monovalent amines such as diethylamine are also sometimes used for the purpose of lowering the degree of polymerization, but particularly good results are often obtained when used in combination with piperazines and hydrazines.

The amount of the above curing agent to be used depends on the average particle diameter of the target particles, the timing of adding the curing agent, and 9! Although it varies depending on the concentration of the suspension, etc., if it is too small, particles that are solid at room temperature cannot be obtained, and if it is too large, the melting point (softening point) tends to be high and no adhesive strength is exhibited. Generally 0.1 for epoxy compounds
It is preferable to use about 0.6 equivalents, but when adding it to an aqueous liquid suspension, the curing reaction becomes a non-uniform reaction, resulting in poor reaction efficiency, so it is good to use 1 equivalent or more. You may receive 1q results.

The general method for adding an amine curing agent to an aqueous liquid suspension is to add the curing agent directly or in the form of an aqueous solution.

In the second method, if the curing agent is added to the mixture of the epoxy compound and the latent curing agent in advance to form an aqueous suspension, then the curing agent is added after the aqueous suspension; When adding the curing agent, it is preferable to allow the curing reaction to occur after the addition of the curing agent by allowing the curing agent to stand still or with gentle stirring.

When the particles are prepared as an aqueous suspension, the particles are separated from the aqueous liquid by the method of neutralizing the whole with mineral acid, etc., if necessary, and then washed or dried at low temperature. Then, it can be taken out as dry particles without damaging the adhesive strength.

The silica-based spherical particles used in the present invention can be obtained by contacting an alkyl silicate with ammonia and water in an alcohol solvent.

Alkyl silicates are ortho-m (Has 10
4) with the general formula 5i (OR>4(R:
Usually, the alkyl group R has about 1 to 5 carbon atoms, but due to the reactivity of alkyl silicates and the ease of obtaining them on an industrial scale, alkyl silicates with 2 to 3 carbon atoms, That is, ethyl silicate, propyl silicate, etc. are preferred.

The alcohol used may be one that dissolves the alkyl silicate, and various liquid alcohols can be used; however, if the number of carbon atoms is too large, the particle size distribution will become broad, which is not preferable. Generally, alkyl alcohols having 1 to 6 carbon atoms can be used, but particularly preferred are alkyl alcohols having 1 to 3 carbon atoms, such as methanol, ethanol, and propatool.

The larger the amount of the alcohol solvent used relative to the alkyl silicate is, the more effective it is to suppress particle aggregation and make the particle size uniform.
50 times, particularly preferably 2 to 20 times.

The amount of water added to hydrolyze the alkyl silicate needs to be at least 4 times the molar ratio of the alkyl silicate, but is usually about 5 to 100 times. Also, the amount of ammonia depends on the type of alkyl silicate used and the purpose'@
Although it may vary depending on the diameter etc., the molar ratio is about 1 to 20 times that of the alkyl silicate.

The silica-based spherical particles are prepared by mixing alkyl ester I~, ammonia, and water in an amount of 10~100'' in an alcohol solvent as described above.
C. Prepared by stirring and mixing for 15 minutes to several hours. In addition,
A hydrocarbon compound can be added to the alcohol solvent. The hydrocarbon used in combination with alcohol is not particularly limited as long as it is compatible with alcohol. From the viewpoint of ease of solvent recovery, price of hydrocarbons, etc., aliphatic, alicyclic, and aromatic hydrocarbons having 5 to 12 carbon atoms are preferred, and those having 6 to 9 carbon atoms are particularly preferred. Examples of particularly preferred hydrocarbons include n-hexane, n-hebutane,
Examples include cyclohexane, methylcyclohexane, benzene, toluene, and xylene.

The mixing ratio of hydrocarbon to alcohol may vary depending on the size of the target particles or other hydrolysis conditions, but usually the weight ratio is 1 part alcohol to 0.
01-5 is preferable, and 0.05-2 is especially preferable.

Addition of hydrocarbons promotes particle size growth and
It has the effect of preventing particle agglomeration.

The silica-based spherical particles obtained by the above method may be treated with a C4 or higher alcohol, a silane coupling agent,
It can be treated with a titanate coupling agent to make it hydrophobic.

The epoxy-based spherical particles used in the present invention serve as an adhesive component,
It is suitably used when the average particle size is 50 μm or less and the particle size variation rate is 100% or less, preferably 50% or less. If the average particle diameter or particle diameter fluctuation rate becomes larger than this, the quality of the liquid crystal display device tends to be impaired.

In addition, the silica-based spherical particles used in the present invention serve as a spacer component, and have an average particle diameter of 10 μm or less and a particle size fluctuation rate of 20 μm or less.
% or less.

When the average particle diameter of the epoxy spherical particles is 2R and the average particle diameter of the spacer particles is 2r, it is suitably used when there is a relationship of r≦2R1, preferably 2r≦2R.

If the average particle diameter of the epoxy-based spherical particles is too small than the average particle diameter of the silica-based spherical particles, the adhesion performance tends to fail.

The epoxy-based spherical particles used in the present invention are prone to secondary agglomeration during drying and are strongly electrostatically charged, so when used alone, they have poor dispersibility over the liquid crystal display device substrate, and uniform dispersion is required. is quite difficult. Furthermore, the silica-based spherical particles used in the present invention tend to undergo secondary aggregation during drying, making it difficult to control the uniformity and clearance of devices.

However, it was surprisingly found that when the epoxy-based spherical particles and the silica-based spherical particles were mixed in advance, the uniformity of dispersion over the device substrate was significantly improved. In particular, when a slurry of epoxy-based spherical particles and a slurry of silica-based spherical particles are mixed using a wet method and then made into a dry mixed powder, secondary agglomeration of particles is less likely to occur, ensuring uniform dispensing, control of rearrangement, and uniformity. - It was found that the dispersibility was significantly improved.

The epoxy-based spherical particles and the silica-based spherical particles used in the present invention are generally mixed by grinding the dry powders together in a mortar, homogenizer, ball mill, or pulverization.

However, since secondary aggregation is likely to occur during the process of forming dry powder, even if macroscopic mixing of the two is possible, it is sometimes quite difficult to release the agglomerated state and perform microscopic mixing. Therefore, the most preferable mixing method is wet mixing. Among these, it is most preferable that epoxy-based spherical particles and silica-based spherical particles be prepared by a wet method as described above and then used in the mixing step in a slurry state without drying. If one or both of them are dry powders, there is a method of sufficiently dispersing them in a surfactant, particularly a nonionic surfactant, or water containing the surfactant, and then mixing them. In any case, when mixing the epoxy-based spherical particles and the silica-based spherical particles in a wet state, it is easy to obtain the best mixing state.

The mixing ratio of epoxy-based spherical particles and silica-based spherical particles varies depending on the particle size and adhesive strength of the epoxy-based spherical particles, but when counted by the number of particles within ±20% of the average particle size. In general, it is preferable to use a range of about 0.01 to 100 epoxy-based spherical particles to one silica-based spherical particle, which tends to exhibit the spacer function and adhesive performance.

[Example] Example 1 Epoxy-based spherical particles were prepared by the following method. Epikote 828, which is a commercially available bisphenol △ diglycidyl ether type epoxy resin, was mixed with 53 and Epicoat 1001.
53 (all made of Yuka shell epoxy) 100cc
13 times of Neugen EA-137 (manufactured by Dai-Kogyo Seiyaku Co., Ltd.), a commercially available polyoxyethylene/phenol-substituted ether surfactant with an HLB of 13, was added to a polycup.

Epicure 17, a phenolic latent curing agent
19 (approximately 0.12 equivalents) of 1N (manufactured by Yuka Shell Epoxy) was added, the whole was heated to 90'C, and stirred quickly to form a transparent compatible solution. Immediately stir at 800 rpm with a Teflon plate blade attached to the tip to prevent the temperature from dropping.
Kneaded for 1 minute. Next, add 6cc of water to the syringe.
．． 5 cc of each was added at 1 minute intervals while stirring at ao o rpm. A milky white emulsion was obtained in the polycup.

Bcc 0.44 equivalents of piperazine was added to this emulsion.
A hardening solution diluted with water was added and stirred gently to homogenize.

After being left at 25°C for 6 days, a slurry containing spherical particles with an average particle diameter of about 4.9 μm was obtained.

Wet classification yields an average particle size of 5 μm and a particle size variation rate of 42%.
After adjusting the distribution, some of the particles were filtered and dried, and their thermal meltability and adhesive strength were measured.

In other words, pour the filtered and dried particles onto a slide glass.
When treated at 40'C, it became transparent and integrated. In addition, place 10 m3 of these particles on a glass slide (75 mm x 25 nm + m, 1 mm thick) and scatter them evenly over a distance of 30 mm from one end. Then, cover the same area with another glass slide and use cellophane tape. Both glass slides were fixed in place. When treated in a hot air dryer at 140°C for 8 hours, the adhesive part did not peel off, but the other parts of the glass slide were destroyed.

Silica-based spherical particles were prepared as follows.

A flask was charged with 100 g of ethanol and 50 y of concentrated ammonia water, and a mixed solution of 20 g of ethyl silicate and 20 g of ethanol was added at 20° C. and 30 Q rpm to generate particle nuclei with an average particle diameter of 1.2 μm.

Furthermore, ethanol 2003, n-hexane 603, and 150 g of concentrated ammonia water were added to the flask, and 8 liquids (mixture of 1 to 100 g of ethyl silicate and ethanol 1009) were added to 12
The mixture was slowly added dropwise for 0 minutes to prepare silica fine particles with an average particle diameter of 2.0 μm.

Most of the solvent is then removed under reduced pressure.

The 1q silica particles were wet classified in a methanol solvent to cut particles of 1.5 μm or less, and the average particle size was 2.0.
A slurry of perfectly spherical silica particles with a particle diameter variation rate of 8.0% was obtained.

The epoxy-based spherical particle slurry and the silica-based spherical particle slurry were mixed at a ratio of approximately 1:1 (the number ratio of particles must be within ±20% of the average particle diameter), and filtered and dried.

The epoxy-based spherical particles and the silica-based spherical particles are mixed in a very good condition, and the chargeability of the powder as a whole is low, making it very easy to spread onto the liquid crystal display device substrate, making it possible to spread it extremely evenly. Ta.

Approximately 1000 pieces/- as epoxy spherical particles on the substrate
After spraying to a certain extent, fix the four circumferences with sealing material, and
Curing treatment was performed at C for 8 hours.

When the liquid crystal was sealed between the boards, it worked stably.

Example 2 Epoxy-based spherical particles were prepared by the following method. 40g of Epicoat 828 used in Example 1 was placed in a 300CC polycup, and Emulgit 9, a polyoxyethylene nonylphenyl ether surfactant with an HLB of 16.2, was placed in a 300CC polycup.
(manufactured by Dai-Kogyo Seiyaku) 49 and 2 cJ (about 0.26 equivalents) of the latent curing agent Epicure 171N used in Example 1 were added and heated to 90°C to form a transparent compatible solution. After cooling to room temperature for 50 minutes, an emulsion was obtained in the same manner as in Example 1 using 24 cc of water.

Approximately O031 dissolved in 32CC water in this emulsion
The piperazine aqueous solution of the present invention was added and cured in the same manner as in Example 1 to obtain a slurry containing spherical particles with an average particle diameter of 19.2 μm.

Wet classification resulted in an average particle size of 13 μm and a particle size variation rate of 15.
% distribution, some of the particles were filtered and dried, and the adhesive strength was measured by the method of Example 1, and the same results as in Example 1 were obtained.

Mix the slurry of the silica-based spherical particles obtained in Example 1 and the slurry of the epoxy-based spherical particles at a ratio of approximately 10:1 (number ratio of particles within ±20% of the average particle diameter); Filter and dry.

The mixing state of both was very good, and the dispersibility to the substrate was very good.

As a liquid crystal display device, it exhibited good performance similar to that of Example 1.

[Effects of the Invention] The powder according to the present invention can be used as an adhesive and a spacer for liquid crystal display devices, and has excellent uniformity of dispersion onto a substrate, and can evenly distribute the spacer particles and adhesive particles anywhere on the dispersion surface. can. As a result, the quality of the liquid crystal display device could be improved.

Special applicant: Toshi Co., Ltd.

Claims (3)

[Claims] (1) A powder composition comprising a mixture of epoxy-based spherical particles and silica-based spherical particles that contain a latent curing agent in a compatible manner inside the particles and are partially cured with an amine compound. (2) Average particle diameter in which the number of epoxy spherical particles is in the range of 0.01 to 100 per silica spherical particle when counted by the number of particles within ±20% of the average particle diameter. Epoxy spherical powder with a diameter of 50 μm or less and an average particle size of 10
The powder composition according to claim 1, wherein the powder composition is a mixture of silica-based spherical powders having a particle diameter of .mu.m or less. (3) The powder composition according to claim (1), wherein the silica-based spherical particles are prepared by hydrolyzing an alkyl silicate.