JPH01234487A - Spherical powdery adhesive and production thereof - Google Patents

Abstract

PURPOSE:To obtain a spherical powdery adhesive, having high adhesive strength especially as a dot adhesive between liquid display elements and maintaining a gap constant, by compatibly containing a fluorinated epoxy resin and latent type curing agent in the interior of particles. CONSTITUTION:The objective adhesive, obtained by compatibly containing (A) a fluorinated epoxy resin, consisting of preferably a resin expressed by the formula (n is 0 or 1) and having >=2 epoxy groups in one molecule and (B) a latent type curing agent consisting of preferably phenolic novolaks, polyvinylphenols, bisphenols, etc., and having 0.3-500mum average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a powder adhesive whose main component is a substantially spherical fluorinated epoxy resin or a silicone-modified epoxy resin, and a method for producing the same.

In more detail, we will introduce a spherical powder adhesive suitable for adhesion of various display devices that are sensitive to impurities and require precise adhesion, such as adhesion between substrates of liquid crystal display elements on which various alignment films are formed, and a method for producing the same. Regarding.

[Prior Art] As a conventional epoxy powder adhesive, a spherical particulate adhesive whose main component is an epoxy resin and contains a latent curing agent inside the particles is disclosed in JP-A-62-174284. ing.

[Problems to be Solved by the Invention] However, for practical purposes, particularly when used for adhering liquid crystal display panels, there is a desire for a powder adhesive having even stronger adhesive strength.

The present invention aims to solve such problems,
The object of the present invention is to provide a spherical powder adhesive with high adhesive strength and a method for producing the same.

[Means to solve the problem] In order to achieve the above object, the present invention consists of the following configuration.

(1) A spherical powder adhesive which contains at least the following components A and B in a compatible manner inside the particles and has an average particle diameter of 0.3 to 500 μm.

A: Fluorinated epoxy resin having at least two or more epoxy groups in one molecule B: Latent curing agent (2) Aqueous dispersion of a mixture in which at least components A and B according to claim (1) are dissolved. 1. A method for producing a spherical powder adhesive, which comprises suspending the adhesive in a medium to prepare a spherical powder.

(3) At least a reaction product of an epoxy resin having two or more epoxy groups in one molecule and a silicone compound represented by the following general formula (II) and a latent curing agent are mutually contained inside the particles. and the average particle diameter is 0.3-5
A spherical powder adhesive characterized in that it is in the range of 00 μm.

(In the formula, R1-R6 are an alkyl group, a phenyl group, or an alkoxy group, R7 is an alkyl group, a phenyl group, an alkoxy group, an epoxy group, an amino group, a carboxyl group,
A hydrocarbon group having a functional group such as a hydroxyl group, R8 is an alkoxy group or an epoxy group, an amino group, a carboxyl group,
a hydrocarbon group having a functional group such as a hydroxyl group, n is a positive integer) (4) At least an epoxy resin having two or more epoxy groups in one molecule and the general formula (II>
A method for producing a spherical powder adhesive, which comprises preparing a spherical powder by suspending a mixture of a reaction product with a silicone compound represented by the formula and a latent curing agent in an aqueous dispersion medium. . ” The present invention will be described in rough detail below.

Examples of the fluorinated epoxy resin having two or more epoxy groups in one molecule of the present invention include bisphenol hexafluoroacetone diglycidyl ether, 1.3-bis[1-
(2,3-epoxypropoxy)-1-trifluoromethyl-2,2,2-trifluoroethyl]benzene, 1
．． 4-bis[1-(2,3-epoxypropoxy)-1
-trifluoromethyl-2,2,2-trifluoromethyl]benzene, 4,4°-bis(2,3-epoxypropoxy)octafluorobiphenyl, etc., and in particular, the following (: "11 formula Bisphenol hexafluoroazetone diglycidyl ether represented by is preferred.

(In the formula, n is O or any positive number.) Bisphenol hexafluoroacetone diglycidyl ether is
Among the expensive fluorinated epoxy resins, it can be produced relatively cheaply, the desired degree of polymerization can be prepared with good reproducibility depending on the reaction conditions, it is highly compatible with other general epoxy resins, and it is easy to handle. It has advantages.

The silicone-modifying epoxy resin used in the present invention has two or more epoxy groups in one molecule, preferably a group that reacts with a silicone compound such as a hydroxyl group in the molecule. What you have is good. Such epoxy resins include bisphenol A epoxy resins,
Bisphenol F type epoxy resin, bisphenol S type epoxy resin, polypropylene glycol diglycidyl ether, dimer acid diglycidyl ester, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triglycidyl-Kanoamine phenol,
Examples include tetraglycidyl aminodiphenylmethane, tetraglycidyl metaxylene diamine, trig, lycidyl isocyanurate, triglycidyl ether triphenylmethane, tetraglycidyl ether tetraphenylethane, and derivatives thereof.

Furthermore, as the silicone compound for modifying the above-mentioned epoxy resin, one represented by the above-mentioned general formula (II) is used, and at least one functional group in one molecule that can react with the epoxy resin, ie, an alkoxy group, epoxy group, amino group, carboxyl group, hydroxyl group, etc.

The spherical powder adhesive of the present invention is mainly composed of a reaction product of the above-mentioned epoxy resin and a silicone compound, and if they are simply mixed without reacting, the silicone compound will be dissolved by the moisture in the air. Hydrolyze or
Alternatively, the silicone compound may undergo migration or other changes over time, which may reduce its functionality as a powder adhesive.

The combination of an epoxy resin and a silicone compound is not particularly limited, but an epoxy resin having a hydroxyl group in the molecule or an epoxy resin obtained by graft polymerization of a polymerizable monomer having a hydroxyl group, and a silicone compound having an alkoxy group as a functional group may be used. A combination is preferable because it can more strongly function as a powder adhesive.

In each of the inventions containing the above-mentioned fluorinated epoxy resin and silicone-modified epoxy resin, it is also possible to use the epoxy resin used in the above-mentioned silicone-modified epoxy resin and derivatives thereof in combination, if necessary. It is also possible to use an epoxy compound having one epoxy group in the molecule, if necessary. Further, in the present invention, it is also possible to use a mixture of the above-mentioned fluorinated epoxy resin and silicone-modified epoxy resin.

In the present invention, a powder made of an epoxy compound containing a fluorinated epoxy resin and/or a silicone-modified epoxy resin is heated and pressed (1 km, 180'C).
It is preferable that the contact angle of the surface of the molded product obtained by the treatment with water for 20 minutes is 75 degrees or more, more preferably 80 degrees or more.

Before preparing the above epoxy resin into a spherical powder, a latent curing agent is added to the epoxy resin. Examples of such curing agents include dicyandiamide, imidazoles, Lewis acid complexes, phenols, bisphenols, phenol novolaks, polyvinylphenols, carboxylic acids, acid anhydrides, acidic polyesters, and carboxyl group-containing styrene-maleic acid copolymers. Examples include polymers, polyamines, modified polyamines, and amine-modified epoxy resins in which a primary or secondary amine is added to the epoxy group of an epoxy resin. Among these, phenolic curing agents such as phenol novolacs, polyvinylphenols, bisphenols and condensates thereof are particularly preferably used as latent curing agents in the present invention.

A combination of the epoxy resin and the latent curing agent that exhibits at least partial compatibility, preferably complete compatibility, is preferably used. In order to make the epoxy compound and the latent curing agent compatible, they can be heated and mixed within a range that does not impair the present invention, or they can be dissolved and mixed in a common good solvent for both, and if necessary, a method such as reducing the pressure can be used. It is best to distill off the solvent.

The amount of latent curing agent used to achieve the present invention is usually 0.05 per equivalent of epoxy group in the epoxy resin.
The range of 1 to 1 equivalent is preferable, but when partially curing with an amine curing agent to form a spherical powder as described later, the optimum value may be found in a considerably small amount. Further, when using a catalytic latent curing agent, it is preferable to use it in an amount of 20% by weight or less based on the weight of the epoxy resin.

A typical method for turning the mixture of the above-mentioned epoxy resin and latent curing agent into spherical powder will be described below.

If the mixture of epoxy resin and latent curing agent is a non-adhesive solid at around room temperature, mechanically pulverized particles may be spheroidized by straining in a heated cylinder or falling by gravity. Method 1), or a method of suspending and dispersing a mixture of an epoxy resin and a latent curing agent in a dispersion medium mainly consisting of water to form spheroids (method 2). Although the present invention does not particularly limit the first method and the second method,
The second method is preferable in consideration of particle uniformity, sphericity, alteration, etc.

There are various methods for suspending the mixture of epoxy resin and latent curing agent in the aqueous dispersion medium in the second method.

Typical methods are listed below, but the method of the present invention is not limited thereto.

(2) A method in which the mixture or its solution is continuously ejected from a nozzle that vibrates in the air or in the liquid, cutting it into droplets and collecting them in the liquid.

(2) A method of ejecting the mixture or its solution in a pulsed manner from a nozzle in the air or in the liquid, and collecting it in the liquid.

(2) A method of emulsifying the mixture or its solution using an emulsifier. Among the above methods, method (1) is particularly preferably used in the present invention from the viewpoint of productivity, but methods (1) to (4) may be used in combination.

In the above method, if the mixture of the epoxy resin and the latent curing agent is liquid at room temperature, it is necessary to partially cure the epoxy resin to form solid spherical particles at least at room temperature. For this purpose, curing agents other than latent curing agents may be used. The curing agent and curing method are not particularly limited, but
■ A method in which a mixture of an epoxy compound and a latent hardener that has been blended with a hardening agent in advance is suspended in an aqueous dispersion medium and partially cured as it is. A method of partially curing by adding an amine curing agent is used.

Regardless of which method is used, in order to harden the suspended particles without bonding them to each other,
Curing conditions at relatively low temperatures are preferred, and therefore room temperature curing agents, particularly amine-based curing agents, are preferably used.

The amine curing agent is prepared by mixing a stoichiometrically calculated equivalent amount of amine with an epoxy resin at room temperature (23°C).
It is preferable that the hardened product has a Shore A hardness of 50 or more after being left for a period of time. When the Shore A hardness is less than 50, the curability of the suspended particles decreases, and it tends to be difficult to obtain a good cured product. Examples of amine-based curing agents that satisfy such characteristics include, but are not limited to, piperazine, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, monoethanolamine, and N(2-aminoethyl)piperazine. isn't it.

The amount of the curing agent used is determined by the average particle diameter of the target particles,
Although it varies depending on the timing of adding the curing agent or the concentration of the suspension, it is usually preferable to use about 0.1 to 0.6 equivalents to the epoxy resin.

However, when added to an aqueous suspension, the curing reaction proceeds from the particle surface, resulting in a non-uniform reaction, and
Good results can sometimes be obtained using tli or more.

As described above, amino groups are introduced into the particles by partially curing with an amine curing agent. Among latent curing agents, amino groups, especially tertiary amino groups, may act as curing accelerators, and low-temperature curing is particularly easy to achieve when a phenolic latent curing agent is used.

In addition, when the mixture of epoxy resin and latent curing agent is solid at room temperature, (1) heating the mixture and suspending it in an aqueous dispersion medium in a liquid state, followed by cooling to form a spherical powder; (2) A method includes suspending a solution of the mixture in an organic solvent in an aqueous liquid and then removing the solvent to form a spherical powder. In the latter method, favorable results are likely to be obtained when using an organic solvent that is poorly soluble in the aqueous dispersion medium. Even when the mixture of the epoxy resin and the latent curing agent is solid at room temperature, the above amine curing agent may be used as necessary.

When prepared as an aqueous suspension, the spherical powder can be separated and recovered by a method such as filtration after neutralization with a mineral acid or the like if necessary.

In the present invention, the average particle diameter of the spherical powder is 0.3 to 500,
czm, preferably from 0.5 to 300 μm, results suitable for the adhesive can be obtained. Average particle size is 0.3μm
Smaller ones are substantially more difficult to prepare and have reduced functionality as adhesives. On the other hand, if the thickness exceeds 500 μm, there are practical problems such as decreased coating properties.

The spherical powder adhesive of the present invention is suitably used as a point adhesive between substrates of a liquid crystal display element. In such applications, large particles are undesirable because they are conspicuous in the display. Furthermore, particles smaller than the gap between the substrates are not preferred because they do not contribute to adhesion.

Generally, the average particle size of the spherical powder used for this purpose is between 1 and 30 μm. It is difficult to directly prepare powders that all fall within this range, and it is preferable to have a sharp particle size distribution, so suitability for use is usually determined by classification.

Although there are no particular limitations on the classification technology, wind selection,
Examples include liquid or dry cyclone, wet or dry sieving, water sieving method (static method, etc.), and it is generally preferable to use a combination of these methods.

When producing the spherical powder adhesive of the present invention, pigments, dyes, antioxidants, lubricants, antistatic agents, etc. may be dispersed or dissolved in the raw material composition. It is also possible to obtain colored particles such as dark-colored particles by preparing pigments, dyes, etc. in the form of spherical powder and then adsorbing them physically or chemically. In addition, ultrafine powder such as silica or alumina is adsorbed or sprinkled on the surface of spherical powder in an aqueous suspension state and/or dry state to improve dispersibility and fluidity.
It is also possible. In addition, it may contain fine powder with a sharp particle size distribution, such as crushed glass fibers, glass spheres, alumina spheres, silica spheres, crosslinked polystyrene spheres, etc., thereby obtaining a powder adhesive containing spacers.

On the other hand, when using an organic solvent, thermoplastic resins that are soluble in organic solvents, specifically acrylic resins, vinyl resins, polyesters, nylon, polyoxide, cellulose derivatives, polysulfone, etc., may impair the present invention. It can also be used within the range. In particular, acrylic or vinyl rubber-like resins are preferred because they form a phase-separated structure when blended with epoxy resins and can impart toughness to the epoxy resins without degrading other properties.

[Example] Examples of the present invention are listed below, but the present invention is not limited thereto.

Example 1 Bisphenol hexafluoroacetone and epichlorohydrin were reacted according to a conventional method to obtain bisphenol hexafluoroacetone diglycidi/L=I-thyl with a melting point of 75°C and an epoxy equivalent of ff1232 (g/eQ,).
This is called fluorinated epoxy resin.)

50 parts by weight of ethyl acetate was added to 100 parts by weight of the fluorinated epoxy resin (■) and 20 parts by weight of the phenolic latent curing agent "Epicure 171N" (manufactured by Yuka Shell Epoxy ■, trade name), and dissolved. A homogeneous solution was obtained. The solution was stirred at room temperature at 60 Orpm with 5% concentration of polyvinyl alcohol (trade name Pagosenol EG-0).
5'', manufactured by Nippon Gosei Kagaku ■) was continuously added to obtain an epoxy resin emulsion. The emulsion was heated to 75°C, and ethyl acetate was removed by volatilization while stirring slowly. After cooling, 50% piperazine (0.6 equivalent to epoxy resin) was added to the emulsion.
A hardening solution dissolved in part by weight of water was added, and the mixture was gently stirred at 25° C. for 4 days to allow partial hardening. Thereafter, it was dehydrated, washed, and dried to obtain a spherical powder with an average particle size of 10.7 μm.

Example 2 In Example 1, 70 parts by weight of fluorinated epoxy resin (■), 30 parts by weight of "Epicure 1001" (manufactured by Yuka Shell Epoxy VtJ, trade name), which is a bisphenol A type epoxy resin, and "Epicure 171N" ( All operations were carried out in the same manner as in Example 1 except that 15 parts by weight of Yuka Shell Epoxy (trade name) (manufactured by Yuka Shell Epoxy ■) was used, and the average particle size was 10.
A 2 μm spherical powder was obtained.

Example 3 In Example 1, 50 parts by weight of fluorinated epoxy resin ■, 25 parts by weight of "'Epicote 1001" (manufactured by Yuka Shell Epoxy ■, trade name), and acrylic copolymer (trade name "
All operations were carried out in the same manner as in Example 1, except that 25 parts by weight of "Tissan Resin NT-850" (manufactured by Teikoku Kagaku Sangyo ■) and 11 parts by weight of "Epicure 171N" (manufactured by Yuka Shell Epoxy ■, trade name) were used. , the average particle diameter is 10.
A spherical powder of 8 μm was obtained.

Example 4 "Epicote 1" which is a bisphenol A type epoxy resin
001'' (manufactured by Yuka Shell Epoxy U, trade name) and structural formula [(C6H5)(CHz) 0.6
7S! 0□, 67 (OCH3> 25 parts by weight of a silicone compound represented by 13 was heated at 175°C under reduced pressure.
The reaction was carried out for a period of time to obtain a silicone-modified epoxy resin (this will be referred to as silicone-modified epoxy resin (2)).

100 parts by weight of the silicone-modified epoxy resin (1) and "Epicure 171N" which is a phenolic latent curing agent.
12 parts by weight of Yuka Shell Epoxy (manufactured by !1, trade name) was weighed out, and 50 parts by weight of ethyl acetate was added thereto and dissolved to obtain a homogeneous solution.

The solution was stirred at room temperature at 700 rpm with 4% concentration of polyvinyl alcohol (trade name "Gohsenol EG-").
05", manufactured by Nippon Gosei Kagaku ■) was continuously added to obtain an epoxy resin emulsion. The emulsion was heated to 75°C, and ethyl acetate was removed by volatilization while stirring slowly.

After cooling to room temperature, a curing solution prepared by dissolving 0.6 equivalents of piperazine based on the epoxy resin in 50 parts by weight of water was added to the emulsion, and the emulsion was gently stirred at 25° C. for 5 days for partial curing. Thereafter, it was dehydrated, washed, and dried to obtain a spherical powder with an average particle diameter of 11.1 μm.

Example 5 In Example 4, silicone-modified epoxy resin ■ was added to 7
5 parts by weight, and 25 parts by weight of "Epicote 828" (manufactured by Yuka Shell Epoxy U, trade name), which is a bisphenol A type epoxy resin, was carried out in exactly the same manner as in Example 1. A spherical powder of 10.6 μm was obtained.

Comparative Example 1 100 parts by weight of "'Epicure 828" (manufactured by Yuka Shell Epoxy ■, trade name) and 20 parts by weight of "Epicure 171N" (manufactured by Yuka Shell Epoxy ■, trade name) were mixed and heated to homogenize. It was made into a compatible solution.

After cooling to room temperature, 70 parts by weight of a 4% polyvinyl alcohol aqueous solution was continuously added to the mixture while stirring at 600 rpm to obtain an epoxy resin emulsion. To the emulsion was added a curing solution prepared by dissolving 0.6 equivalents of piperazine based on the epoxy resin in 60 parts by weight of water.
The mixture was gently stirred at 5° C. for 4 days to allow partial curing. Thereafter, it was dehydrated, washed, and dried to obtain a spherical powder with an average particle size of 10.8 μm.

Evaluation of Adhesiveness Regarding the spherical powder adhesives obtained in Examples 1 to 5 and Comparative Example 1, the adhesiveness was evaluated according to the procedure shown below in accordance with JIS K-6853r "Tearing and tearing strength test method".

(a) Polyimide alignment film (product name “Sunever”, 8
1 ml of the measurement sample is uniformly sprinkled on the center (15 x 15 mm) of the ITO-coated glass substrate 5 x 25 x 1 mm coated with Sankagaku 11) l).

(b) Another glass substrate was placed on top of the glass substrate, and heat and pressure treatment was performed at a load of 600 g/-1 and a temperature of 180° C. for 2 hours.

(c) Fix aluminum blocks to this test piece from both sides with instant adhesive to use it as a test piece for measurement.

(d) Set the above test piece in a tensile tester and perform measurement at a tensile speed of 0.5 mm/min (23° C., 60% RH).

The measurement results are shown in Table 1, and it was found that the spherical powder adhesive containing the fluorinated epoxy resin or silicone-modified epoxy resin of the present invention had good adhesive strength.

Table 1 [Effects of the Invention] The spherical powder adhesive of the present invention has excellent adhesive strength and exhibits high adhesive strength as a point adhesive between substrates related to electronic materials, especially liquid crystal display elements, and can maintain a constant gap. Maintains high performance.

Claims (7)

[Claims] (1) A spherical powder adhesive which contains at least the following components A and B in a compatible manner inside the particles and has an average particle diameter of 0.3 to 500 μm. A: Fluorinated epoxy resin having at least two or more epoxy groups in one molecule B: Latent curing agent (2) The spherical powder adhesive according to claim (1), wherein the fluorinated epoxy resin is a fluorinated epoxy resin represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, n is 0 or any positive number) (3) A method for producing a spherical powder adhesive, characterized by preparing a spherical powder by suspending a mixture in which at least components A and B according to claim (1) are dissolved in an aqueous dispersion medium. . (4) A claim characterized in that a compatible solution of a fluorinated epoxy resin and a latent curing agent suspended in an aqueous dispersion medium is partially cured with a water-soluble amine curing agent to form a spherical powder. (3) A method for producing a spherical powder adhesive as described. (5) At least a reaction product of an epoxy resin having two or more epoxy groups in one molecule and a silicone compound represented by the following general formula (II) and a latent curing agent are mutually contained inside the particles. and the average particle diameter is 0.3 to 50
A spherical powder adhesive characterized by having a diameter of 0 μm. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_1 to R_6 are alkyl groups, phenyl groups, or alkoxy groups, R_7 is alkyl groups, phenyl groups,
Hydrocarbon group having a functional group such as an alkoxy group or an epoxy group, an amino group, a carboxyl group, a hydroxyl group, R_8
(n is a positive integer) (6) an epoxy resin having at least two or more epoxy groups in one molecule; and general formula (II) according to claim (5).
A method for producing a spherical powder adhesive, which comprises preparing a spherical powder by suspending a mixture of a reaction product with a silicone compound represented by the formula and a latent curing agent in an aqueous dispersion medium. . (7) The method for producing a spherical powder adhesive according to claim (6), characterized in that the mixture suspended in an aqueous dispersion solvent is partially cured with a water-soluble amine curing agent to prepare a spherical powder. .