JP2740615B2 - Epoxy resin composition suitable for laser printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition suitable for laser printing, which is used for insulating coating of electric / electronic parts and which can apply clear laser irradiation to the surface of the insulating coating. It is.

[0002]

2. Description of the Related Art Conventionally, thermosetting and ultraviolet curable inks have been used for printing on electric / electronic parts insulated with an epoxy resin composition to specify characteristics and model numbers. For the purpose of streamlining the process, a method for printing in a shorter time has been demanded. As one of the methods to cope with this, a printing system using laser irradiation has attracted attention. In this laser printing system, a portion irradiated with a laser in the form of a character or pattern is discolored by thermal energy, or the irradiated portion is sublimated and the surface is roughened, and the character or pattern can be identified by scattering of light. . The printing time of this method is 0.01 second or less, which is much shorter than the conventional heat or ultraviolet curable ink requiring several minutes to several tens of minutes for curing. However, when a conventional insulating coating of an epoxy resin composition is irradiated with a laser, discoloration does not occur simply by roughening the coating surface, and clear characters and patterns cannot be printed.

[0003] Recently, it has been found that when a conventional epoxy resin composition contains yellow ferric hydroxide, the color changes from yellow to brown by laser irradiation (Japanese Patent Application Laid-Open No. Sho 62-62).
No. 50360). However, since ferric hydroxide is yellow, it can only be used for hues such as yellow or orange, and it is a future task to apply black laser printing on blue and green bases, especially light-colored bases. And has been.

[0004]

SUMMARY OF THE INVENTION The present invention has been intensively studied to obtain a resin composition which changes from a blue or green light color to a black color by laser, which was impossible in the prior art, and as a result, it contains copper (II) tartrate. Then, they found that the color changed from light blue to black when irradiated with a laser, and based on this finding, further advanced various studies and completed it. It is an object of the present invention to provide an epoxy resin composition which gives a cured product capable of giving a clear print on a resin surface by irradiating a laser without deteriorating electric characteristics and other various characteristics. is there.

[0005]

SUMMARY OF THE INVENTION The present invention provides copper (II) tartrate.
The present invention relates to an epoxy resin composition suitable for laser printing, comprising: The reason why copper (II) tartrate is used in the epoxy resin composition of the present invention will be described below. Copper (II) tartrate is a pale blue powder, which when heated decomposes at 200-300 ° C. and changes to copper (II) oxide, turning black. Therefore, when the epoxy resin composition containing copper (II) tartrate is irradiated with a laser in the form of letters or patterns, the resin surface is heated by the thermal energy of the laser, and the copper (II) tartrate contained in the resin becomes A chemical reaction occurs and turns black. That is, only the portion irradiated with the laser becomes black, and the portion not irradiated remains light blue, so that a black character or pattern can be clearly printed on the light blue base.

The average particle size of the copper (II) tartrate used in the present invention is preferably 100 μm or less. The reason is that when copper (II) tartrate is mixed and dispersed in the epoxy resin composition, if the average particle diameter is 100 μm or more, the surface becomes spot-like when coated on an electronic / electric part, which only lowers the commercial value of the part. Dispersion tends to be insufficient, and when laser irradiation is performed, discoloration does not occur in portions where copper (II) tartrate does not exist, characters and patterns are cut off, and clear printing may not be possible. The average particle size is suitably determined by weight-averaging the particle size distribution obtained by a Coulter counter (manufactured by Nikkaki), but may be determined by a measuring method other than the Coulter counter. The content of copper (II) tartrate is 0.5 to
20% by weight is preferred. The reason for this is that if the content is 0.5% by weight or less, the degree of discoloration is small even when irradiated with a laser, so that clear printing is not obtained. This is because it is difficult to satisfy the original performance as an insulating material for electronic components.

The epoxy resin used in the present invention includes, for example, diglycidyl ether type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, phenol novolak type epoxy resin and cresol novolak type epoxy resin. Examples include resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, chain aliphatic type epoxy resins, heterocyclic type epoxy resins, halogenated epoxy resins, and the like, but are not limited thereto. As the curing agent and curing accelerator used in the present invention, acid anhydride, polyamine, novolak type phenol resin,
There are a secondary amine, an imidazole compound and the like, and any of them may be used. If necessary, known inorganic fillers such as zircon powder, talc powder, crystalline silica powder, fused silica powder, calcium carbonate powder, magnesia powder, calcium silicate powder, hydrated alumina powder, alumina powder and the like may be blended. .

[0008] The resin composition obtained by the present invention usually exhibits a light blue color depending on the color tone of copper (II) tartrate.
Green, black, and white pigments may be used in combination. The resin composition of the present invention may be in any state such as a liquid state such as a casting material, a powder state such as a powder coating, a granular state such as a molding material, and a lump. As a method for producing the resin composition of the present invention, for example, when raising the case of a powder coating, after sufficiently mixing the raw material components weighed at a predetermined ratio by a mixer, melt-kneading with an extruder, a co-kneader or a roll, Then, there is a method of pulverizing with a pulverizer. Examples of the method of performing insulating coating of electronic and electric parts with the powder coating obtained by the above method include general powders such as a fluid immersion method, an electrostatic fluid immersion method, a rolling method, a sprinkling method, a hot spray method, and an electrostatic spray method. There is a body painting method. Also, casting materials and molding materials can be manufactured by known techniques and used as insulating materials.

[0009]

Next, the present invention will be described in more detail with reference to examples. << Example 1 >> Bisphenol A type epoxy resin (epoxy equivalent 950) 50 parts by weight Copper (II) tartrate (average particle size 5 μm) 5 parts by weight Crystalline silica powder 50 parts by weight 2-methylimidazole 1 part by weight The above composition is blended. Then, the mixture was blended with a Henschel mixer, melt-kneaded with a co-kneader, and then pulverized with a pulverizer to obtain a powder coating of an epoxy resin composition having an average particle size of 60 to 70 μm.

Example 2 A powder coating of an epoxy resin composition having an average particle size of 60 to 70 μm was obtained in the same manner as in Example 1 except that the addition amount of copper (II) tartrate was changed to 20 parts by weight. Was. << Comparative Example 1 >> In Example 1, the addition amount of copper (II) tartrate was changed to 0.1 part by weight, and the other conditions were the same.
A powder coating of an epoxy resin composition of about 70 μm was obtained. << Comparative Example 2 >> In Example 1, the addition amount of copper (II) tartrate was changed to 50 parts by weight, and the other conditions were the same.
A 70 μm epoxy resin composition powder coating was obtained.

Cured products were prepared from the resin compositions of Examples 1 and 2 and Comparative Examples 1 and 2. The sample was irradiated with laser using a carbon dioxide laser (Ushio 400 model laser mark, energy 6 Joule) through a predetermined mask for 1 / 100,000 seconds to mark the cured product surface. In addition, the dielectric breakdown voltage of the cured product is determined in accordance with JIS K
6911. Table 1 shows the results.

[0012]

[Table 1]

[0013]

According to the present invention, when the epoxy resin composition suitable for laser printing according to the present invention is used as an insulating coating material, clear printing can be performed on the resin surface by laser irradiation without deteriorating the electrical characteristics and other characteristics. Can be provided. Therefore, since printing can be performed in a much shorter time than in the past, the production process of electric / electronic parts can be rationalized.

Claims (3)

(57) [Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent, a filler and the like, wherein the epoxy resin composition contains copper (II) tartrate. 2. The average particle size of copper (II) tartrate is 100 μm.
The epoxy resin composition according to claim 1, wherein: 3. Copper (II) tartrate is added to the composition in an amount of 0.5%.
3 to 20 parts by weight.
The epoxy resin composition according to the above.