JPH06910B2 - Spherical powder adhesive and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a powder adhesive mainly composed of a fluorinated epoxy resin or a silicone-modified epoxy resin having a substantially spherical shape, and a method for producing the same.

More specifically, the present invention relates to a spherical powder adhesive which is suitable for adhesion of various display devices that dislike impurities such as adhesion between substrates of liquid crystal display elements on which various alignment films are formed and which requires precise adhesion, and a manufacturing method thereof. .

[Prior Art] As a conventional epoxy powder adhesive, a spherical powder adhesive composed of an epoxy resin as a main component and containing a latent curing agent inside the particles is disclosed in JP-A-62-174284. There is.

[Problems to be Solved by the Invention] However, practically, a powder adhesive having a stronger adhesive force is desired especially when it is used for adhesion of a liquid crystal display panel.

The present invention is intended to solve such problems,
An object of the present invention is to provide a spherical powder adhesive having high adhesion and a method for producing the same.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

"(1) A spherical powder adhesive characterized in that at least the following components A and B are compatiblely contained inside the particles and the average particle diameter is 0.3 to 500 µm.

A: Fluorinated epoxy resin having at least two epoxy groups in one molecule B: Latent type curing agent (2) At least a mixture of components A and B according to claim 1 is compatible with an aqueous solution. A method for producing a spherical powder adhesive, which comprises suspending in a dispersion 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 compatibly contained inside the particles. And the average particle size is 0.3 to 500μ.
A spherical powder adhesive characterized by being in the range of m.

(In the formula, R _{1 to} R ₆ are alkyl groups, phenyl groups or alkoxy groups, R ₇ is a hydrocarbon having a functional group such as an alkyl group, a phenyl group, an alkoxy group or an epoxy group, an amino group, a carboxyl group and a hydroxyl group. Group, R ₈ is a hydrocarbon group having a functional group such as an alkoxy group or an epoxy group, an amino group, a carboxyl group or a hydroxyl group, n is a positive integer) (4) At least two or more epoxies in one molecule A mixture of a reaction product of an epoxy resin having a group and the silicone compound represented by the general formula (II) and a latent curing agent is suspended in an aqueous dispersion medium to prepare a spherical powder. A method for producing a spherical powder adhesive, comprising: The present invention will be described in more detail below.

The fluorinated epoxy resin having two or more epoxy groups in one molecule of the present invention includes bisphenol hexafluoroacetone diglycidyl ether and 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 and the like can be mentioned, and bisphenol hexafluoroacetone diglycidyl ether represented by the following structural formula is particularly preferable. .

(In the formula, n is 0 or any positive number.) Bisphenolhexafluoroacetone diglycidyl ether can be produced at a relatively low cost among expensive fluorinated epoxy resins and has a desired degree of polymerization depending on the reaction conditions. It has the advantages that it can be prepared with good reproducibility, it has high compatibility with other general epoxy resins, and it is easy to handle.

The silicone-modifying epoxy resin used in the present invention is one having two or more epoxy groups in one molecule, and preferably has a group reactive with a silicone compound such as a hydroxyl group in the molecule. I like what you have. Examples of such epoxy resin include bisphenol A type epoxy resin,
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-p-aminophenol,
Examples thereof include tetraglycidylaminodiphenylmethane, tetraglycidyl metaxylenediamine, triglycidyl isocyanurate, triglycidyl ether triphenylmethane, tetraglycidyl ether tetraphenylethane and derivatives thereof.

As the silicone compound for modifying the above-mentioned epoxy resin, the one represented by the general formula (II) is used, and a functional group capable of reacting with one or more epoxy resins in at least one molecule, that is, an alkoxy group. It must have a group, epoxy group, amino group, carboxyl group, hydroxyl group and the like.

The spherical powder adhesive of the present invention is mainly composed of a reaction product of the above-mentioned epoxy resin and silicone compound, and when they are simply mixed and used without reacting, the silicone compound may be changed by moisture in the air. There is a possibility that the function as a powder adhesive may deteriorate because it changes with time such as hydrolysis or the migration of the silicone compound.

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

In each of the above inventions containing a fluorinated epoxy resin and a silicone-modified epoxy resin, the epoxy resin used in the silicone-modified epoxy resin and a derivative thereof may be used in combination, if necessary. Further, if necessary, an epoxy compound having one epoxy group in the molecule can be used. 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 powdery material comprising an epoxy compound containing a fluorinated epoxy resin and / or a silicone-modified epoxy resin is heated and pressed (1 kg / cm ² , 180 ° C. ×
The contact angle of water on the surface of the molded product obtained by the treatment for 20 minutes) is preferably 75 ° or more, and more preferably 80 ° or more.

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

A combination showing at least partial compatibility, preferably complete compatibility, between the epoxy resin and the latent curing agent is preferably used. In order to make the epoxy compound and the latent curing agent compatible with each other, both are heated and mixed within a range not impairing the present invention, or both are dissolved and mixed in a good solvent common to both, and if necessary, a method such as decompression is used. It is better to distill off the solvent with.

The amount of latent curing agent used to achieve the present invention is usually 0.05 per 1 equivalent of epoxy groups of the epoxy resin.
The range of 1 to 1 equivalent is preferable, but in the case of partial curing with an amine-based curing agent to form a spherical powder as described below, a considerably small amount may have an optimum value. Further, when a catalyst type latent curing agent is used, it is preferable to use 20% by weight or less based on the weight of the epoxy resin.

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

When the mixture of the epoxy resin and the latent curing agent is a non-adhesive solid at around room temperature, the mechanically pulverized particles are spheroidized by a method such as floating or gravity falling in a heating cylinder (first Method), or a method in which a mixture of an epoxy resin and a latent curing agent is suspended and dispersed in a water-based dispersion medium to form a sphere (second method). In the present invention, the first method and the second method are not particularly limited,
The second method is preferable in consideration of particle uniformity, sphericity, alteration and the like.

There are various methods for suspending the mixture of the epoxy resin and the latent curing agent in the aqueous dispersion medium by the second method. Next, a typical method will be described, but the method of the present invention is not limited thereto.

A method of continuously discharging the mixture or a solution thereof from a nozzle vibrating in the air or in a liquid to cut the mixture or the solution into droplets, and collecting the mixture in the liquid.

A method of ejecting the mixture or a solution thereof in a pulse form from a nozzle in air or a liquid and collecting the mixture in the liquid.

A method of emulsifying the mixture or a solution thereof with an emulsifier.

Among the above methods, the method from the viewpoint of productivity is particularly preferably used in the present invention, but the methods of to may be used in combination.

In the above method, when 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, a curing agent other than the latent curing agent may be used. Although the curing agent and the curing method are not particularly limited,
A method of suspending a mixture of an epoxy resin and a latent curing agent that have been mixed with a curing agent in advance in an aqueous dispersion medium to partially cure the mixture, and a water-soluble amine-based suspension in an aqueous suspension of the mixture of the epoxy resin and the latent curing agent. For example, a method of adding a curing agent and performing partial curing is used.

Whichever of the above methods is used, in order to cure the particles in suspension without bonding them to each other,
Curing conditions at a relatively low temperature are preferable, and therefore a room temperature curable curing agent, particularly an amine curing agent is preferably used.

The amine-based curing agent is a stoichiometrically equivalent amount of amine mixed with an epoxy resin at room temperature (23 ° C.), and at room temperature
It is preferable that the Shore A hardness of the cured product after standing for 50 hours is 50 or more. If 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 piperazine, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, monoethanolamine, and N (2-aminoethyl) piperazine, but are not limited thereto. is not.

The amount of the curing agent used is 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 equivalent to the epoxy resin. However, when added to the aqueous suspension, the curing reaction proceeds from the particle surface, resulting in a heterogeneous reaction, and good results may be obtained even if 1 equivalent or more is used.

An amino group is introduced into the particles by partially curing with the amine-based curing agent as described above. An amino group, especially a tertiary amino group, may serve as a curing accelerator in some latent curing agents, and it is easy to achieve low temperature curing particularly when a phenolic latent curing agent is used.

When the mixture of the epoxy resin and the latent curing agent is solid at room temperature, the mixture is heated to suspend it in a liquid state in an aqueous dispersion medium, and then cooled to obtain a spherical powder. There is a method in which an organic solvent solution of the mixture is suspended in an aqueous liquid and then desolvated to give a spherical powder. In the latter method, preferable results are easily obtained when an organic solvent which is poorly soluble in the aqueous dispersion medium is used. Even when the mixture of the epoxy resin and the latent curing agent is solid at room temperature, the amine curing agent may be used if necessary.

When prepared as an aqueous suspension, the spherical powder can be separated and recovered by a method such as filtration after being neutralized 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 μm.
When m, preferably 0.5 to 300 μm, suitable results as an adhesive can be obtained. Those having an average particle size of less than 0.3 μm are substantially difficult to prepare, and the function as an adhesive decreases. On the other hand, when it exceeds 500 μm, there is a problem in practical use such as a decrease in coating property.

The spherical powder adhesive of the present invention is preferably used as a point adhesive between substrates of a liquid crystal display device. In such applications, the presence of large particles is noticeable in the display, which is not preferable. Further, particles smaller than the gap between the substrates do not contribute to the adhesion, which is not preferable. Generally, the spherical powder used for this purpose has an average particle size of 1 to 30 μm. Since it is difficult to directly prepare powders all of which fall within this range, and it is preferable that the particle size distribution is sharp, the usability is usually adjusted by classification.

Although there is no particular limitation on the classification technique, wind selection,
Examples include liquid or dry cyclones, wet or dry sieving, and water sluice method (stationary method, etc.), which are generally preferably used in combination.

In the production of the spherical powder adhesive of the present invention, pigments, dyes, antioxidants, lubricants, antistatic agents and the like may be dispersed or dissolved in the raw material composition. It is also possible to obtain colored particles such as dark colors by physically or chemically adsorbing the pigments and dyes in the form of spherical powder. It is also possible to improve the dispersibility and fluidity by adsorbing or sprinkling ultrafine powder such as silica or alumina on the surface of the spherical powder in the aqueous suspension state and / or the dried state. Furthermore, fine powder with a sharp particle size distribution,
For example, it may contain ground glass fibers, glass spheres, alumina spheres, silica spheres, cross-linked polystyrene spheres, etc., whereby a powder adhesive containing spacers is obtained.

On the other hand, when an organic solvent is used, a thermoplastic resin soluble in an organic solvent, specifically, acrylic resin, vinyl resin, polyester, nylon, polycarbonate, polyacetal, polyphenylene oxide, cellulose derivative, polysulfone, etc. It can also be used within a range that does not impair the present invention. In particular, an acrylic or vinyl rubber-like resin is preferable because it can form a phase-separated structure when blended with an epoxy resin and impart toughness to the epoxy resin without degrading other properties.

[Examples] Examples of the present invention will be given 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 diglycidyl ether having an epoxy equivalent of 232 (g / eq.) At a melting point of 75 ° C. (this is referred to as fluorinated epoxy resin I). ).

50 parts by weight of ethyl acetate was added to 100 parts by weight of the fluorinated epoxy resin I and 20 parts by weight of "Epicure 171N" (trade name of Yuka Shell Epoxy Co., Ltd.), which is a phenol-based latent curing agent, and dissolved. To obtain a uniform solution.
While stirring the solution at room temperature at 600 rpm, polyvinyl alcohol having a concentration of 5% (trade name "Gosenol EG-0
An epoxy resin emulsion was obtained by continuously adding 100 parts by weight of an aqueous solution of 5 ", manufactured by Nippon Synthetic Chemical Industry Co., Ltd. The temperature of the emulsion was raised to 75 ° C, and ethyl acetate was removed by volatilization with slow stirring. After cooling to room temperature, a hardening liquid prepared by dissolving 0.6 equivalent of piperazine in 50 parts by weight of water with respect to the epoxy resin was added to the emulsion, and the emulsion was added at 4 ° C at 25 ° C.
The mixture was gently stirred for a day to partially cure it. Then dehydration,
It was washed and dried to obtain a spherical powder having an average particle diameter of 10.7 μm.

Example 2 In Example 1, 70 parts by weight of fluorinated epoxy resin I and “Epicoat 1001” which is a bisphenol A type epoxy resin (trade name of Yuka Shell Epoxy Co., Ltd.) are used.
Except that 30 parts by weight and 15 parts by weight of "Epicure 171N" (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) were used, and the same operation as in Example 1 was performed, and the average particle diameter was 10.2 μm. A powder was obtained.

Example 3 In Example 1, 50 parts by weight of fluorinated epoxy resin I, 25 parts by weight of "Epicoat 1001" (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), and an acrylic copolymer (trade name "Taisan Resin") were used. NT-850 ", 25 parts by weight of Teikoku Chemical Industry Co., Ltd. and" Epicure 171 "
The same operation as in Example 1 was carried out except that 11 parts by weight of N ″ (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) was used to obtain a spherical powder having an average particle diameter of 10.8 μm.

Example 4 "Epicoat 1" which is a bisphenol A type epoxy resin
001 ”(trade name of Yuka Shell Epoxy Co., Ltd.)
5 parts by weight and structural formula [(C ₆ H ₅ ) (CH ₃ ) _0.67 SiO
_0.67 (OCH ₃ )] ₃ 25 parts by weight of a silicone compound was reacted under reduced pressure at 175 ° C. for 3 hours to obtain a silicone-modified epoxy resin (this is referred to as silicone-modified epoxy resin I).

100 parts by weight of the silicone modified epoxy resin I and "Epicure 171" which is a phenol-based latent curing agent.
12 parts by weight of N "(trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) was weighed, and 50 parts by weight of ethyl acetate was added thereto and dissolved to obtain a uniform solution. Polyvinyl alcohol with a concentration of 4% while stirring (trade name "Gothenol EG-05", manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
An epoxy resin emulsion was obtained by continuously adding 90 parts by weight of the aqueous solution. The emulsion was heated to 75 ° C., and ethyl acetate was removed by volatilization with slow stirring. After cooling to room temperature, the emulsion contains 0.6% of epoxy resin.
A curing liquid prepared by dissolving an equivalent amount of piperazine in 50 parts by weight of water was added, and the mixture was partially stirred at 25 ° C. for 5 days for partial curing. Then, it is dehydrated, washed and dried to have an average particle size of 11.
A 1 μm spherical powder was obtained.

Example 5 In Example 4, the silicone-modified epoxy resin I was
5 parts by weight, bisphenol A type epoxy resin "Epicoat 828" (produced by Yuka Shell Epoxy Co., Ltd.,
The same operation as in Example 1 was carried out except that 25 parts by weight of (trade name) was used to obtain a spherical powder having an average particle diameter of 10.6 μm.

Comparative Example 1 "Epicoat 828" (produced by Yuka Shell Epoxy Co., Ltd.,
100 parts by weight of trade name and 20 parts by weight of "Epicure 171N" (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) were mixed and heated to obtain a uniform compatible solution. After cooling to room temperature, 70 parts by weight of a 4% aqueous solution of polyvinyl alcohol was continuously added while stirring the mixture 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 in 60 parts by weight of water with respect to the epoxy resin, and the mixture was stirred gently at 25 ° C. for 4 days to partially cure it. Then, it was dehydrated, washed and dried to obtain a spherical powder having an average particle diameter of 10.8 μm.

Evaluation of Adhesiveness With respect to the spherical powder adhesives obtained in Examples 1 to 5 and Comparative Example 1, the adhesiveness was evaluated according to the procedure described below according to JIS K-6853 "Cleaving adhesive strength test method".

(A) A glass substrate with ITO coated with a polyimide alignment film (trade name “San Ever”, manufactured by Nissan Chemical Industries, Ltd.) (2
1 mg of the measurement sample is evenly dispersed in the central portion (15 × 15 mm) of 5 × 25 × 1 mm).

(B) Another glass substrate is overlaid, and the load is 600 g / cm ² ,
Heat-pressure treatment is performed at a temperature of 180 ° C. for 2 hours.

(C) An aluminum block is fixed to this test piece from both sides with an instant adhesive to form a test piece for measurement.

(D) The above test piece is set in a tensile tester, and measurement is carried out 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 the silicone-modified epoxy resin of the present invention has a good adhesive force.

EFFECTS OF THE INVENTION The spherical powder adhesive of the present invention has excellent adhesive strength, exhibits high adhesive strength as a point adhesive between substrates of liquid crystal display devices, particularly for liquid crystal display devices, and maintains a constant gap. Has high performance.

Claims (7)

[Claims] 1. A spherical powder adhesive characterized in that at least the following components A and B are compatibly contained in the inside of the particles and the average particle diameter is 0.3 to 500 μm. A: Fluorinated epoxy resin having at least two epoxy groups in one molecule B: Latent curing agent 2. A fluorinated epoxy resin is represented by the following general formula (I):
The spherical powder adhesive according to claim 1, which is a fluorinated epoxy resin represented by: (In the formula, n is 0 or any positive number) 3. A spherical powder adhesive, characterized in that it is prepared into a spherical powder by suspending a mixture of at least the components A and B according to claim 1 in an aqueous dispersion medium. Production method. 4. A spherical powder is prepared by partially curing a compatible solution of a fluorinated epoxy resin and a latent curing agent suspended in an aqueous dispersion medium with a water-soluble amine curing agent. A method for producing the spherical powder adhesive according to claim (3). 5. A reaction product of at least 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 compatible with each other inside the particles. And has an average particle size of 0.3
A spherical powder adhesive characterized in that it is ˜500 μm. (In the formula, R _{1 to} R ₆ are alkyl groups, phenyl groups or alkoxy groups, R ₇ is a hydrocarbon having a functional group such as an alkyl group, a phenyl group, an alkoxy group or an epoxy group, an amino group, a carboxyl group and a hydroxyl group. Group, R ₈ is a hydrocarbon group having a functional group such as an alkoxy group or an epoxy group, an amino group, a carboxyl group, and a hydroxyl group, and n is a positive integer) 6. An epoxy resin having at least two epoxy groups in one molecule and the general formula (I) according to claim (5).
A spherical powder adhesive characterized by preparing a spherical powder by suspending a mixture of a reaction product with a silicone compound represented by I) and a latent curing agent in an aqueous dispersion medium. Production method. 7. The spherical powder adhesive according to claim 6, wherein the mixture suspended in an aqueous dispersion solvent is partially cured with a water-soluble amine curing agent to prepare a spherical powder. Production method.