JPS61148274A - Epoxy resin powder coating composition - Google Patents

Abstract

PURPOSE:To produce the titled compound having remarkably excellent thermal shock resistance and moisture resistance as an insulating coating of electrical or electronic parts, by compounding a filler containing a specific amount of polyethylene wax or microcrystalline wax. CONSTITUTION:The objective composition is produced by adding 0.5-40wt% polyethylene wax and/or mirocrystalline wax to the filler of an epoxy resin powder coating and kneading the filler together with an epoxy resin and a hardener.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention is an epoxy resin powder coating that is used as an insulating coating coating for electric/electronic parts by blending polyethylene wax and/or microcrystalline wax. The present invention relates to a powder coating composition characterized by improved thermal shock resistance and temperature resistance.

[Prior Art 1] In recent years, powder coatings have been increasingly used in place of solvent-based coatings. Among these, as insulation coating paints for electrical and electronic parts, compared to solvent-based paints, it has advantages such as reduced painting man-hours, automation of the painting process, and superior properties of coated parts. Epoxy resin powder coatings are now mainly used.

In this way, epoxy resin powder coatings are used for insulating coatings on electrical and electronic parts, but recently it has become clear that even if these electrical and electronic parts are subjected to thermal shock, their appearance and characteristics will not change, and that they can be treated by boiling. Extremely strict requirements have been placed on materials, such as that their appearance and characteristics remain unchanged even when they are subjected to pressure steam treatment at a pressure of 1 atm or more (so-called pressure steamer treatment).

These conventional epoxy resin powder coatings used for insulating coatings on electrical and electronic components consist of epoxy resin, curing agents, fillers, pigments, additives, etc., and are uniformly melted and kneaded, then pulverized into powder. It is used as body paint. As the epoxy resin, a solid resin such as a bisphenol A glycidyl ether type epoxy resin or a borac glycidyl ether type epoxy resin is used, and in some cases, a liquid resin is used.

As the curing agent, various amine curing agents, dicyandiamide derivatives, imiguzol conductors, acid anhydrides, etc. are used.

As the filler, inorganic powders such as silica, alumina, alumina, and calcium carbonate are used. others,
It consists of pigments or additives for coloring.

With such conventional powder coatings, it is difficult to achieve both the moisture resistance and thermal shock resistance described in 011.

For example, improvements in thermal shock resistance have been achieved by incorporating epoxy resins that are compatible, but this results in poor moisture resistance, such as in front-line treatment. On the other hand, improvement in moisture resistance has been achieved by increasing the heat deformation temperature of the cured product, but this results in poor thermal shock resistance.

[Objective of the invention 1 Thermal shock resistance and moisture resistance are required characteristics that are incompatible with each other, but as a result of repeated research to achieve both properties, we have found that polyethylene wax and/or microcrystalline wax are suitable for epoxy resin powder coatings. Of the fillers,
It has been found that both can be achieved by blending 0.5 to 30% (weight %, same hereinafter).

Thermal shock resistance is improved by blending polyethylene wax and/or microcrystalline wax.
1) Water repellency is imparted and moisture resistance is improved.

[Structure of the Invention I#, 1 The polyethylene wax used in the present invention is a low molecular weight polyethylene wax with a molecular weight of about 1 f) On, crystallized once, and has high density, medium density, and low density. Either can be used, but lower density is preferred.

It is also possible to use microcrystalline wax, which is a refined petroleum product and has a structure similar to that of synthesized polyethylene wax. The polyethylene wax and microcrystalline wax may be used together or in combination.

The melting point of the polyethylene wax and/or microcrystalline wax of the present invention is preferably 50 to 200°C. If the temperature is below 50℃, the wax will easily solidify with each other as a powder coating, and the wax will melt and flow out of the powder during powder coating, baking, and reliability testing. , the combination effect will be lost.

In addition, if the temperature is less than 2 (1r) °C, the powder coating's I
It does not melt when forming ft and has no effect on imparting flexibility. Furthermore, it is preferable to use a material having a melting point that melts during firing. Since the firing temperature varies depending on the application, it is preferable that the melting point is about 10 to 20°C lower than the firing temperature used. For example, 15
In applications where firing is performed at 0°C, 100 to 130°C is preferable.

The shape of the polyethylene wax and/or microcrystalline wax of the present invention does not matter, including solid lumps, flakes, and powder, as long as it can be uniformly melted and kneaded during the production of powder coatings.

14= The blending amount of the polyethylene wax and/or microcrystalline wax of the present invention is preferably 5 to 30% based on the epoxy resin. If it is less than 0.5%, there will be no blending effect because it is a small amount, and if it is more than 30%, the powder coating will flow, the appearance will be poor, and the adhesion to the object to be coated will be poor. will have poor moisture resistance. More preferably, the best effects on thermal shock resistance and moisture resistance can be obtained when the epoxy resin is blended in an amount of 3 to 10%.

The epoxy resin used in the present invention may be any epoxy resin used in conventional epoxy resin powder coatings, and the filler is a conventional inorganic powder as the main component, and polyethylene wax and/or microcrystalline wax is added to the epoxy resin. against C), 5-3
Add 0%. The amounts of other components such as curing agents, pigments, additives, and their constituent components are not limited.

As mentioned above, as the composition of the epoxy resin powder coating, by blending polyethylene wax and/or microcrystalline wax with a melting point of 50 to 2 ('l r) °C to the epoxy resin in an amount of +1.5 to 30%, the epoxy resin powder coating can be baked. When melted and stretched like a resin, an epoxy resin powder coating composition is imparted with flexibility and water repellency, and has extremely excellent moisture resistance and thermal shock resistance.

=5- As described in "Effects of the Invention 1 and 2" above, by blending polyethylene wax and/or microcrystalline wax with the epoxy resin powder coating, it can be used as an insulating coating coating for electrical and electronic parts and has thermal shock resistance and moisture resistance. It has the feature of being significantly improved.

[Example 1 A powder coating was prototyped using the formulation (parts by weight) shown in Table 1,
Examples No. 1 and No. 2 and comparative examples No. 1 and No. 2 were used.

The manufacturing conditions for the powder coating were adjusted by melt-kneading at 70 to 80°C, cooling, and pulverizing.

The coating was applied to the IKΩ resistor network by a fluidized dip coating method (preheated to 150°C), and baked at 150°C for 12 hours.

The resistance value of the resistor was measured using a digital multimeter.

Thermal shock resistance was determined by repeatedly heating and cooling at -50°C for 30 minutes and at 125°C for 30 minutes, and the number of cracks generated in the appearance was determined.

Moisture resistance was evaluated by performing a pressure cooker treatment at 2.1 atm (120° C.) for 10 hours and determining the rate of change in resistance value.

Table 1 *1 Manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat EP-
1004 pieces 2 Neowax LS, Yasushi Oil Co., Ltd. Melting point: 110±5°C As can be seen from Tables 1 and 2, the examples have better thermal shock resistance than the comparative examples. It is understood that the rate of change in resistance value is extremely small, or that the epoxy resin powder coating has both thermal shock resistance and moisture resistance.

Patent applicant Sumitomo Bakelite Co., Ltd. Sumitomo Durez Co., Ltd.

Claims (2)

[Claims] (1) An epoxy resin powder coating consisting of an epoxy resin, a curing agent, a filler, etc., characterized in that the filler contains 0.5 to 30% by weight of polyethylene wax and/or microcrystalline wax. Body paint composition. (2) The epoxy resin powder coating composition according to claim 1, wherein the polyethylene wax and/or microcrystalline wax has a melting point of 50 to 200°C.