JP4622428B2 - Epoxy resin powder coating and manufacturing method thereof - Google Patents

Description

  The present invention relates to an epoxy resin powder coating material and a method for producing the same.

  Epoxy resin powder coatings have excellent electrical, mechanical, and thermal properties, and contain less solvent than solvent-based coatings. Insulation protection of electronic parts, OA equipment, home appliances, building materials, automobile parts, etc., because of advantages such as being able to be used immediately after painting, being relatively inexpensive, and being able to collect and use excess paint during painting In recent years, there is a high demand for decorative paints.

  Among them, in particular, in applications where electrical and electronic parts are insulated and insulated, if the coating film is cracked or chipped due to rapid heating expansion or external impact, dielectric breakdown occurs, so the mechanical strength of the coating film There is always a need for improvement.

As a means for improving the mechanical strength of the coating film, for example, there is a method of imparting flexibility to the coating film using an appropriate amount of an internal plasticized liquid epoxy resin together with a normal epoxy resin (for example, Patent Document 1). reference.).
However, when a large amount of low melting point epoxy resin is blended, the melting point of the powder coating material is lowered, and problems such as fusion of particles of the powder coating material occur.

There is also a method of using an epoxy resin having a large molecular weight. Since the epoxy resin powder coating is solid at room temperature, an epoxy resin having a higher molecular weight than that of the liquid epoxy resin coating can be blended. As a result, it is possible to prevent the particles of the epoxy resin powder coating from fusing with each other and to significantly improve the mechanical strength of the coating film.
However, since an epoxy resin having a large molecular weight usually has a high melting point and is hard, when it is blended in a large amount, it becomes difficult to uniformly disperse the raw material mixture at the time of melt kneading when producing an epoxy resin powder coating, and the grindability is poor. Problems such as inability to finely pulverize, high resin viscosity at the time of melting the coating, and difficulty in obtaining a good coating appearance occur.

  As described above, in conventional epoxy resin powder coatings, there are limits to the amount of low melting point epoxy resin or high molecular weight epoxy resin, and it may be difficult to impart the desired properties.

Japanese Patent Laid-Open No. 05-279552

  The present invention provides an epoxy resin powder paint capable of forming a coating film excellent in mechanical strength without impairing productivity and coating characteristics, and a method for producing the same.

Such an object is achieved by the following present inventions (1) to (6).
(1) An epoxy resin powder coating containing an epoxy resin and a curing agent thereof, wherein the epoxy resin has a first epoxy resin having an epoxy equivalent of 2000 or more and a softening point of 70 ° C. or less. An epoxy resin powder paint comprising a second epoxy resin.
(2) Content of said 1st epoxy resin is 25 to 75 weight% with respect to the whole epoxy resin.
The epoxy resin powder coating according to (1) above.
(3) The content of the first epoxy resin is 40 to 85% by weight based on the total of the first epoxy resin and the second epoxy resin. Powder paint.
(4) The epoxy resin powder coating according to any one of (1) to (3), further containing an inorganic filler.
(5) The epoxy resin powder coating according to any one of (1) to (4), wherein the total amount of the epoxy resin and the curing agent is 20 to 95% by weight with respect to the entire powder coating.
(6) The method for producing an epoxy resin powder paint according to any one of (1) to (5) above,
(A) a step of melt-mixing a raw material mixture containing the first epoxy resin and the second epoxy resin and not containing a curing agent;
(B) A method for producing an epoxy resin powder coating, comprising: a step of melt-mixing the remaining raw material mixture containing a curing agent into the molten mixture.

  The present invention contains an epoxy resin and its curing agent, and contains, as an epoxy resin, a first epoxy resin having an epoxy equivalent of 2000 or more and a second epoxy resin having a softening point of 70 ° C. or less. This is an epoxy resin powder coating characterized in that it can form a coating film excellent in mechanical strength without impairing productivity and coating characteristics as compared with conventional ones. .

Hereinafter, the epoxy resin powder coating of the present invention and the production method thereof will be described.
The epoxy resin powder paint of the present invention (hereinafter sometimes simply referred to as “powder paint”) is an epoxy resin powder paint containing an epoxy resin and a curing agent thereof, The epoxy resin contains a first epoxy resin having an epoxy equivalent of 2000 or more and a second epoxy resin having a softening point of 70 ° C. or less.
In addition, the method for producing the powder paint of the present invention includes:
(A) melt-mixing a raw material mixture containing a first epoxy resin and a second epoxy resin and not containing a curing agent;
(B) a step of melt-mixing the remaining raw material mixture containing a curing agent into the molten mixture;
It is characterized by having.
First, the powder coating material of the present invention will be described in detail.

The powder coating material of the present invention uses a first epoxy resin having an epoxy equivalent of 2000 or more as an epoxy resin. Thereby, high mechanical strength can be imparted to the coating film.
And considering the productivity of the powder coating material, the smoothness of the coating film surface, etc., it is preferable to use those having an epoxy equivalent of 2000 or more and 4500 or less.

Although it does not specifically limit as said 1st epoxy resin, For example, in addition to bisphenol type epoxy resins, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, these are bromine. Brominated bisphenol type epoxy resin. These can be used alone or in combination of two or more.
Among these, bisphenol A type epoxy resins and bisphenol F type epoxy resins can be suitably used from the viewpoint of paintability and cost.

The powder coating material of the present invention uses, as the epoxy resin, a second epoxy resin having a softening point of 70 ° C. or lower together with the first epoxy resin.
Thereby, while being able to provide the said effect by the said 1st epoxy resin, it can suppress that the productivity at the time of powder coating manufacture falls.

Although it does not specifically limit as said 2nd epoxy resin, For example, bisphenol type epoxy resins, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, phenol novolak type epoxy resin In addition to novolak type epoxy resins such as cresol novolak type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, aromatic amine type epoxy resins, brominated epoxy resins obtained by brominating these, and the like. These can be used alone or in combination of two or more.
Among these, bisphenol A type epoxy resin and bisphenol F type epoxy resin can be suitably used because of low melt viscosity and low cost.

In addition to the first epoxy resin and second epoxy resin, other epoxy resins can be used in combination with the powder coating material of the present invention.
Although it does not specifically limit as said epoxy resin which can be used together, For example, bisphenol type epoxy resins, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, phenol novolac type epoxy resin, Examples thereof include novolak type epoxy resins such as cresol novolak type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, aromatic amine type epoxy resins, and brominated epoxy resins obtained by brominating these. These can be used alone or in combination of two or more.

In the powder coating of the present invention, the amount of the epoxy resin is not particularly limited, but the content of the first epoxy resin is preferably 25 to 75% by weight with respect to the entire epoxy resin. More preferably, it is 30 to 65% by weight. Thereby, the effect of the mechanical strength improvement of a coating film by a 1st epoxy resin can be heightened.
If the blending amount of the first epoxy resin is less than the above lower limit, a sufficient mechanical strength improvement effect may not be obtained. On the other hand, when the above upper limit is exceeded, depending on the formulation of the powder coating, the viscosity at the time of heating and melting may increase, and coating defects such as a decrease in the appearance of the coating film may occur.

Moreover, it is preferable that content of a 1st epoxy resin is 40 to 85 weight% with respect to the sum total of a 1st epoxy resin and a 2nd epoxy resin. More preferably, it is 45 to 75% by weight.
Thereby, the said effect by a 1st epoxy resin can be expressed, without reducing the productivity and storage stability of a powder coating material.
When the content of the first epoxy resin is less than the above lower limit, depending on the type of the second epoxy resin, the mechanical strength of the coating film may be reduced, or the particles of the powder coating material may be fused. There is a case. On the other hand, when the above upper limit is exceeded, depending on the formulation of the powder coating, the viscosity at the time of heating and melting may increase, and coating defects such as a decrease in the appearance of the coating film may occur.

The above-mentioned epoxy resin curing agent is used in the powder coating of the present invention.
Here, the curing agent is not particularly limited, and various types can be used singly or in combination depending on the type of epoxy resin to be used and the purpose to which the powder coating is applied.
Specifically, for example, aromatic amines such as diaminodiphenylmethane and aniline resins, condensates of aliphatic amines and aliphatic dicarboxylic acids, dicyandiamide and its derivatives, various imidazoles and imidazoline compounds, adipic acid, sebacic acid, phthalic acid , Polycarboxylic acids such as maleic acid, trimellitic acid, benzophenone dicarboxylic acid and pyromellitic acid or their anhydrides, dihydrazides such as adipic acid and phthalic acid, phenols, cresols, xylenol, bisphenol A, etc. Novolacs,
Examples thereof include carboxylic acid amides, methylolated melamines, and block type isocyanurates.
Among these, an acid anhydride curing agent is particularly preferable. Thereby, the hardening characteristic of a powder coating material can be improved.

  In addition, in the powder coating material of this invention, hardening accelerators, such as tertiary amines, imidazoles, and an organic phosphorus compound, can be used together with the said hardening | curing agent as needed. In the present invention, for the sake of convenience, these curing accelerators are also referred to as curing agents.

  Although the compounding quantity of the said hardening | curing agent can be suitably selected with the kind of epoxy resin to be used and a hardening | curing agent, when the characteristic of hardened | cured material is considered, generally 0.6-1.2 with respect to an epoxy resin. It is preferable to use in an equivalent range.

In the powder coating material of the present invention, the total amount of the epoxy resin and the curing agent is preferably 20 to 95% by weight with respect to the whole powder coating material. More preferably, it is 40 to 70% by weight.
Thereby, the applicability | paintability of a powder coating material can be made favorable. If the total amount is less than the lower limit value, the smoothness of the coating film may be reduced. On the other hand, if the total amount is higher than the upper limit value, the appearance of the coating film such as sagging or togari during firing is a curing step after coating. May occur.

  In addition to the epoxy resin and the curing agent described above, an inorganic filler can be added to the powder coating material of the present invention. Thereby, while being able to adjust the fluidity | liquidity of a powder coating material, mechanical strength and heat resistance can be provided to a coating film.

  The inorganic filler used here is not particularly limited. For example, calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide, crystals or fused silica, talc, kaolin, clay, mica, dolomite , Wollastonite, glass fiber, glass beads, zircon, titanium compound, molybdenum compound and the like. These can be used alone or in combination of two or more.

  Although it does not specifically limit as a particle size of the said inorganic filler, Usually, a 5-30 micrometers thing is preferably used as an average particle diameter. Thereby, favorable fluidity | liquidity is provided at the time of powder coating melting | fusing, coating property improves more, and also it can be made optimal also about the mechanical strength of a coating film.

When the inorganic filler is blended in the powder coating of the present invention, the blending amount is not particularly limited, but is preferably 10 to 80% by weight based on the whole powder coating. More preferably, it is 30 to 60% by weight.
Thereby, the applicability | paintability of a powder coating material can be made favorable. If the blending amount is less than the lower limit, the blending effect of the inorganic filler may not be sufficient. On the other hand, when the amount is larger than the upper limit, the smoothness of the coating film may be lowered.

  In addition to the components described above, the powder coating material of the present invention includes various pigments, flame retardants, leveling agents, additives such as coupling agents and antifoaming agents, etc. within the range not impairing the effects of the present invention. Can be blended. These can be used alone or in combination of two or more.

Next, the method for producing a powder coating material of the present invention (hereinafter sometimes simply referred to as “manufacturing method”) will be described in detail.
The production method of the present invention is a method for producing the above-described powder coating material of the present invention,
(A) melt-mixing a raw material mixture containing a first epoxy resin and a second epoxy resin and not containing a curing agent;
(B) a step of melt-mixing the remaining raw material mixture containing a curing agent into the molten mixture;
It is characterized by having.

In the production method of the present invention, first,
(A) A raw material mixture containing the first epoxy resin and the second epoxy resin and not containing the curing agent is melt-mixed.

The raw material mixture melt-mixed in the step (a) contains the first epoxy resin and the second epoxy resin. Since the second epoxy resin used here has a low softening point and a low melt viscosity, the melt mixture obtained in the step (a) has a lower melt viscosity than the first epoxy resin. be able to. Thereby, the thermal history required at the time of the melt mixing in the (b) process mentioned later can be reduced.
Furthermore, this raw material mixture does not contain a curing agent. Thereby, a molten mixture can be prepared, without giving a comparatively high heat history required in (a) process to a hardening | curing agent.

Next, in the production method of the present invention,
(B) The remaining raw material mixture containing the curing agent is melt-mixed into the molten mixture.

  In the step (b), the remaining raw material mixture containing the curing agent is melted and mixed with the molten mixture obtained in the step (a). In the step (a), the first epoxy resin having a high melt viscosity and the second epoxy resin having a low melt viscosity are already melt-mixed, and the melt mixture used in the step (b) has a melt viscosity of Since it has been optimized to a sufficiently low level, it can be sufficiently mixed with the remaining raw material mixture containing the curing agent with a thermal history smaller than that in the step (a).

Thus, the manufacturing method of this invention has the said (a) process and (b) process, It is characterized by the above-mentioned.
As described above, by performing the melt mixing of the raw materials in two stages, even if a material having a high melt viscosity and requiring a high heat history for melt kneading is used like the first epoxy resin, the heat given to the curing agent Melting and mixing can be performed with sufficient accuracy while minimizing the history. As a result, it is possible to optimize the melting characteristics of the powder coating material, to reduce the variation in characteristics, and to effectively develop the mechanical strength improvement effect by the first epoxy resin.

Although it does not specifically limit as embodiment which implements the manufacturing method of this invention, For example,
(1) In the step (a), in addition to the epoxy resin containing the first epoxy resin and the second epoxy resin, a raw material mixture containing an additive such as an inorganic filler and a pigment is melt-kneaded, and then ( In the step b), a method in which a curing agent is mixed and melt mixed in the molten mixture obtained in the step (a),
(2) In the step (a), the first epoxy resin and the second epoxy resin are melt-kneaded, and then in the step (b), the molten mixture obtained in the step (a) is added to the first mixture. A method of mixing and melting and mixing a raw material mixture containing an epoxy resin other than the second epoxy resin, an inorganic filler, an additive, and a curing agent;
Etc. can be applied.
In the method (1), the raw material mixture used in step (a) may contain all raw materials other than the curing agent. For example, a part of the second epoxy resin, A part or all of an epoxy resin other than the first and second epoxy resins, an inorganic filler, an additive and the like can be used together with the curing agent in the step (b). However, it is preferable to use the entire amount of the first epoxy resin in the step (a).

  In the production method of the present invention, in addition to the steps (a) and (b), other steps can be incorporated. For example, the molten mixture obtained in the step (a) can be used as it is in the step (b), but can also be used after being cooled and coarsely pulverized. Moreover, after the step (b), it is possible to usually have a step of cooling the obtained product and pulverizing it to a predetermined particle size.

In the production method of the present invention, the apparatus used in the steps (a) and (b) is not particularly limited, and an apparatus usually used for production of a powder coating material can be applied.
For example, a mixer such as a concrete mixer or a Hensial mixer can be used for preparing the raw material mixture, and a melt mixing device such as an extruder, a twin-screw kneader, or a pressure kneader can be used for the melt mixing of the raw material mixture. Ordinary reaction devices equipped with a stirrer, a temperature controller and the like can be used. Further, after melt mixing, the powder coating material can be obtained by pulverizing to a suitable particle size using a pulverizer such as a hammer mill and a ball mill, and performing classification operation.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example. In the examples and comparative examples, “parts” indicates “parts by weight” and “%” indicates “% by weight”.

<Example 1>
As the first epoxy resin, 75 parts of “Epicoat 1010” (bisphenol A type epoxy resin) manufactured by Japan Epoxy Resin Co., Ltd. As the second epoxy resin, “Epicoat 828” (bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.) ) 25 parts, as epoxy resin other than these, 50 parts by “Epicoat 5051” (brominated bisphenol A type epoxy resin) manufactured by Japan Epoxy Resin Co., Ltd., and “A-1” (crystal) manufactured by Tatsumori Co., Ltd. as inorganic filler Crushing silica) 120 parts, as pigment, 29 parts manufactured by Ishihara Sangyo Co., Ltd. “TTO-55” (white pigment / titanium oxide), manufactured by Sumitomo Chemical Co., Ltd., 1 part “Cyanine Blue GH” (blue pigment / cyanine blue), cup As a ring agent, Nippon Unicar Co., Ltd., "A-187" (silane coupling agent) 0.3 part, mixer It was prepared raw material mixture in combination. This was charged into a pressure kneader, melt mixed at 150 ° C. for 60 minutes, then cooled and coarsely pulverized.
Next, 15 parts of BTDA (benzophenone tetracarboxylic acid anhydride) and 0.2 part of 2-methylimidazole are added as a curing agent to the coarsely pulverized product and mixed with a mixer. Supply was made so that the supply amount per hour was constant, and a molten mixture having a discharge temperature of 105 ° C. was obtained. This was pulverized after cooling and classified to obtain a powder coating having an average particle size of 50 μm.

<Example 2>
As the first epoxy resin, 45 parts of “Epicoat 1010” (bisphenol A type epoxy resin) manufactured by Japan Epoxy Resin Co., Ltd. As the second epoxy resin, “Epicoat 1001” (bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.) ) A powder paint was obtained in the same manner as in Example 1 except that 55 parts were used.

<Example 3>
As the first epoxy resin, 75 parts of “Epicoat 1010” (bisphenol A type epoxy resin) manufactured by Japan Epoxy Resin Co., Ltd. As the second epoxy resin, “Epicoat 828” (bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.) ) 25 parts were charged into a reactor equipped with a stirrer, a reflux condenser and a thermometer, melt mixed at 150 ° C. for 120 minutes, then cooled and coarsely pulverized.
Next, as the epoxy resin other than the first and second epoxy resins, 25 parts of “Epicoat 1002” (bisphenol A type epoxy resin) 25 parts and Japan Epoxy Resin Co., Ltd.・ 25 parts of “Epicoat 5051” (brominated bisphenol A type epoxy resin), manufactured by Tatsumori Co., Ltd. as an inorganic filler, 120 parts of “A-1” (crystal crushed silica), manufactured by Ishihara Sangyo Co., Ltd., “TTO” -55 "(white pigment / titanium oxide) 29 parts, manufactured by Sumitomo Chemical Co., Ltd." Cyanine Blue GH "(blue pigment / cyanine blue) 1 part, as a coupling agent, Nippon Unicar Co., Ltd." A-187 "(silane Coupling agent) 0.3 part, BTDA (benzophenone tetracarboxylic anhydride) 15 part, 2-methylimidazole 0.2 part as a curing agent In addition, the mixture was mixed with a mixer, and this was supplied to a twin-screw kneader so that the supply amount per unit time was constant, thereby obtaining a molten mixture having a discharge product temperature of 105 ° C. This was pulverized after cooling and classified to obtain a powder coating having an average particle size of 50 μm.

<Comparative Example 1>
As epoxy resin, Japan Epoxy Resin, "Epicoat 1001" (bisphenol A type epoxy resin) 25 parts, Japan Epoxy Resin, "Epicoat 1002" (bisphenol A type epoxy resin) 75 parts, Japan Epoxy Resin Co., Ltd. -"Epicoat 5051" (brominated bisphenol A type epoxy resin) 50 parts, manufactured by Tatsumori as inorganic filler-"A-1" (crystal crushed silica) 120 parts, manufactured by Ishihara Sangyo Co., Ltd.-"TTO -55 "(white pigment / titanium oxide) 29 parts, manufactured by Sumitomo Chemical Co., Ltd." Cyanine Blue GH "(blue pigment / cyanine blue) 1 part, as a coupling agent, Nippon Unicar Co., Ltd." A-187 "(silane Coupling agent) 0.3 parts, BTDA (benzophenone tetracarboxylic acid anhydride) 15 parts as curing agent Was prepared raw material mixture was mixed in a mixer by adding 0.2 parts of 2-methylimidazole.
This was supplied to the twin-screw kneader so that the supply amount per unit time was constant, and a molten mixture having a discharge temperature of 95 ° C was obtained. This was pulverized after cooling and classified to obtain a powder coating having an average particle size of 50 μm.

<Comparative Example 2>
As epoxy resins, Japan Epoxy Resin, "Epicoat 1010" (bisphenol A type epoxy resin) 40 parts, Japan Epoxy Resin, "Epicoat 1002" (bisphenol A type epoxy resin) 30 parts, Japan Epoxy Resin Co., Ltd.・ Epicoat 5051 (brominated bisphenol A type epoxy resin) 80 parts, Tatsumori Co., Ltd. as inorganic filler ・ A-1 (crystal crushed silica) 120 parts, Ishihara Sangyo Co., Ltd. as pigment ・ TTO -55 "(white pigment / titanium oxide) 29 parts, manufactured by Sumitomo Chemical Co., Ltd." Cyanine Blue GH "(blue pigment / cyanine blue) 1 part, as a coupling agent, Nippon Unicar Co., Ltd." A-187 "(silane Coupling agent) 0.3 parts, BTDA (benzophenone tetracarboxylic acid anhydride) 15 parts as curing agent Was prepared raw material mixture was mixed in a mixer by adding 0.2 parts of 2-methylimidazole.
This was supplied to the twin-screw kneader so that the supply amount per unit time was constant to obtain a molten mixture having a discharge product temperature of 108 ° C. This was pulverized after cooling and classified to obtain a powder coating having an average particle size of 50 μm.

  Table 1 shows the raw material compositions of Examples and Comparative Examples, and the results of evaluation of the obtained powder coating materials. The raw materials used and the evaluation methods are as follows.

1. Raw materials A. First epoxy resin (1) manufactured by Japan Epoxy Resin Co., Ltd. “Epicoat 1010” (bisphenol A type epoxy resin / epoxy equivalent 4000: softening point 148 ° C.)

B. Second epoxy resin (1) “Epicoat 828” manufactured by Japan Epoxy Resin Co., Ltd. (bisphenol A type epoxy resin / epoxy equivalent 189: liquid at room temperature)
(2) “Epicoat 1001” manufactured by Japan Epoxy Resin Co., Ltd. (bisphenol A type epoxy resin / epoxy equivalent 475: softening point 64 ° C.)

C. Epoxy resins other than the first and second epoxy resins (1) Made by Japan Epoxy Resin Co., Ltd. “Epicoat 1002” (bisphenol A type epoxy resin / epoxy equivalent 650, softening point 78 ° C.)
(2) “Epicoat 5051” manufactured by Japan Epoxy Resin Co., Ltd. (brominated bisphenol A type epoxy resin / epoxy equivalent 625, softening point 105 ° C.)

D. Inorganic filler (1) "A-1" (manufactured by Tatsumori Co., Ltd.)

E. Pigment (1) Ishihara Sangyo "TTO-55" (white pigment / titanium oxide)
(2) “Cyanine Blue GH” manufactured by Sumitomo Chemical Co., Ltd. (blue pigment / cyanine blue)

F. Additive (coupling agent)
(1) Nippon Unicar Co., Ltd. “A-187” (silane coupling agent)

G. Curing agent (1) BTDA: benzophenone tetracarboxylic anhydride (2) 2MZ: 2-methylimidazole

2. Evaluation Method (1) Smoothness About 20 g of powder coating material was uniformly spread in an aluminum dish, and the surface smoothness after heating this at 150 ° C. for 30 minutes with a drying apparatus was judged visually. Each code is as follows.
○: The surface is smooth.
X: The surface has wavy undulations, pinholes or protruding foreign matters, and is not smooth.

(2) Gel time Measured on a hot platen at 165 ° C. according to JIS C 2161.

(3) Bending strength In accordance with JIS K 7203, a bending fracture test was performed under the following conditions to measure the bending strength.
Distance between fulcrums: 40mm
Test piece: width 10 mm, thickness 2 mm
Test speed: 5mm / min

(4) Tensile stress Based on JIS K7113, the bending tensile fracture test was done on the following conditions, and the tensile stress was measured.
Test piece: width 4 mm, thickness 0.5 mm
Distance between grips: 10mm
Test speed: 5mm / min

Examples 1 to 3 are all powder coating materials of the present invention containing a first epoxy resin having an epoxy equivalent of 2000 or more and a second epoxy resin having a softening point of 70 ° C. or less, A coating film excellent in mechanical strength could be formed. Moreover, the smoothness of the coating film was also good.
On the other hand, since Comparative Example 1 did not use the first epoxy resin, the mechanical strength was greatly reduced. In Comparative Example 2, the second epoxy resin was not used, and the melt mixing was performed in a temperature range where the reaction between the epoxy resin and the curing agent did not proceed substantially, but the first epoxy resin had a high melt viscosity and was dispersed. Since the mixing property was insufficient, both the mechanical strength and smoothness of the coating film were reduced.

  The epoxy resin powder coating material of the present invention has good paintability and high mechanical strength, and is particularly suitably used for a coating film of an epoxy resin powder coating material used for the purpose of insulating exterior electrical and electronic parts. be able to.

Claims (6)

An epoxy resin powder coating containing an epoxy resin and a curing agent thereof, wherein the epoxy resin includes a first epoxy resin having an epoxy equivalent of 2000 or more and a softening point of 70 ° C. or less. An epoxy resin powder coating comprising an epoxy resin. 2. The epoxy resin powder coating material according to claim 1, wherein the content of the first epoxy resin is 25 to 75 wt% with respect to the entire epoxy resin. 3. The epoxy resin powder coating according to claim 1, wherein the content of the first epoxy resin is 40 to 85 wt% with respect to the total of the first epoxy resin and the second epoxy resin. Furthermore, the epoxy resin powder coating material in any one of Claim 1 thru | or 3 containing an inorganic filler. The epoxy resin powder coating material according to any one of claims 1 to 4, wherein a total amount of the epoxy resin and the curing agent is 20 to 95% by weight with respect to the entire powder coating material. A method for producing an epoxy resin powder coating material according to any one of claims 1 to 5, comprising: (a) the first epoxy resin and the second epoxy resin, and no curing agent. Melting and mixing the raw material mixture;
(B) melt-mixing the remaining raw material mixture containing a curing agent into the molten mixture;
The manufacturing method of the epoxy resin powder coating material characterized by having.