JPH0662835B2 - Epoxy resin composition for laser printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used for an insulating coating of an electric / electronic component, and an epoxy resin for laser printing capable of sharply printing the surface of the insulating coating by laser irradiation. It relates to a composition.

[Conventional technology]

Conventionally, a thermosetting ink or an ultraviolet curable ink has been used for printing on an electric / electronic component insulation-coated with an epoxy resin composition in order to clearly indicate its characteristics and model number. As a result, there is a demand for a method capable of printing in a shorter time.

As one of the countermeasures against this, a printing system using laser irradiation is drawing attention. In this laser marking system, the part irradiated with laser in characters or patterns is discolored by heat energy, or the irradiated part is sublimated and surface roughened, and characters or patterns can be identified by scattering of light. The printing time of this method is 0.01 seconds or less, which is significantly shorter than the conventional heat-curable or UV-curable ink which requires several minutes to several tens of minutes for curing.

However, when the insulating coating of the conventional epoxy resin composition is irradiated with a laser, the coating surface is simply roughened, discoloration does not occur, and a clear character pattern cannot be printed.

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. (JP 62-50360).

However, since ferric hydroxide is yellow, it can be used only for hues such as yellow and orange, and a blue or green substrate,
Especially, it is possible to apply black laser printing on a light-colored base,
It has been regarded as a future issue.

[Problems to be Solved by the Invention]

The present invention, as a result of earnestly studying to obtain a resin composition that changes from a blue or green bright color to a black color by a laser, which has been impossible in the past, as a result, when copper carbonate was contained, a light blue to a black color was obtained when irradiated with a laser. It was found that the present invention was discolored, and based on this finding, various researches were conducted to complete the present invention.

An object of the present invention is to provide an epoxy resin composition which gives a cured product capable of sharply marking a resin surface by laser irradiation without deteriorating electrical properties and other properties. is there.

[Means for Solving the Problems]

The present invention relates to an epoxy resin composition for laser printing, which contains copper carbonate.

The reason why copper carbonate is used in the epoxy resin composition of the present invention will be described below.

Copper carbonate is a light green powder, and when heated, it is decarbonated at 300 to 400 ℃ and changes to copper (II) oxide, which turns black.

Therefore, when the epoxy resin composition containing copper carbonate is irradiated with a laser in a letter or pattern, the resin surface is heated by the thermal energy of the laser, and the copper carbonate contained in the resin causes the above chemical reaction to turn black. Become. That is, only the portion irradiated by the laser becomes black, and the non-irradiated portion remains light green, so that black characters or patterns can be clearly printed on the light green substrate.

The average particle size of the copper carbonate used in the present invention is 100 μm.
The following is preferable. The reason for this is that when copper carbonate is mixed and dispersed in an epoxy resin composition, an average particle size of 100 μm or more causes spots on the surface when it is coated on electronic and electrical components, which not only reduces the commercial value of the component but also disperses it. Is likely to be insufficient, and when irradiated with laser, discoloration does not occur in a portion where copper carbonate does not exist, and characters or patterns may be interrupted to make clear printing impossible.

In addition, this average particle size
It is appropriate to obtain the particle size distribution by a weight average of the particle size distribution obtained by Co., Ltd., but it may be obtained by a measuring method other than the Coulter counter.

The content of copper carbonate is preferably 0.5 to 20% by weight. The reason for this is that if the content is 0.5% by weight or less, the degree of discoloration even when irradiated with laser is small and clear printing cannot be performed, while if it exceeds 20% by weight, the electrical insulation of the resin composition deteriorates. This is because it is difficult to satisfy the original performance as an insulating material for electronic and electrical parts.

Examples of the epoxy resin used in the present invention include diglycidyl ether type epoxy resins such as bisphenol A type epoxy resins and bisphenol F type epoxy resins, phenol novolac type epoxy resins, novolac type epoxy resins such as cresol novolac type epoxy resins, and glycidyl. Examples thereof include ester type epoxy resins, glycidyl amine type epoxy resins, linear 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, novolac type phenol resin,
There are tertiary amines, imidazole compounds and the like, but 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, and alumina powder may be added. .

The resin composition obtained according to the present invention usually exhibits a light green color depending on the color tone of copper carbonate, but pigments such as red, blue, green, black and white may be used together.

The resin composition of the present invention may be in a liquid state such as a casting material, a powder state such as a powder coating material, a granular state such as a molding material or a lump state.

As a method for producing the resin composition of the present invention, for example, in the case of powder coating, after thoroughly mixing the raw material components weighed at a predetermined ratio with a mixer, melt kneading with an extruder, a co-kneader or a roll, Then, there is a method of crushing with a crusher. As a method for performing insulation coating of electronic and electrical parts with the powder coating obtained by the above method, a fluidized immersion method, an electrostatic fluidized immersion method, a rolling method,
A general powder coating method such as a sprinkling method, a hot spray method, or an electrostatic spray method is used.

Also, in the case of a casting material or a molding material, it can be manufactured by a known technique and can be used as an insulating material.

〔Example〕

 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 carbonate (average particle size 10 μm) 5 parts by weight Crystalline silica powder 50 parts by weight 2 Methylimidazole 1 part by weight The above composition was blended and blended with a Henschel mixer. Then, after melt-kneading with a cokneader, it was pulverized with a pulverizer to obtain a powder coating material of an epoxy resin composition having an average particle diameter of 60 to 70 μm.

Example 2 In Example 1, the amount of copper carbonate added was changed to 20 parts by weight,
Otherwise in the same manner, a powder coating material of an epoxy resin composition having an average particle size of 60 to 70 μm was obtained.

Comparative Example 1 A powder coating material of an epoxy resin composition having an average particle diameter of 60 to 70 μm was obtained in the same manner as in Example 1, except that the addition amount of copper carbonate was changed to 0.1 part by weight.

Comparative Example 2 In Example 1, the amount of copper carbonate added was changed to 50 parts by weight,
Otherwise in the same manner, a powder coating material of an epoxy resin composition having an average particle size of 60 to 70 μm was obtained.

Cured products were prepared from the resin compositions of Examples 1 and 2 and Comparative Examples 1 and 2.

A carbon dioxide laser (400 type laser mark energy density 6 Joule / cm ² manufactured by Ushio Inc.) was applied to this sample with a laser through a predetermined mask for 1 millionth of a second to mark the surface of the cured product. gave.

The insulation coating voltage of the cured product was measured according to JIS K6911. The results are shown in Table-1.

[Effects of the Invention] When the laser-printing epoxy resin composition of the present invention is used as an insulating coating material, it is possible to perform clear printing on the resin surface by laser irradiation without deteriorating electrical characteristics and other characteristics. It is possible to provide a coating capable of
Therefore, since printing can be performed in a much shorter time than in the past, the production process of electric and electronic parts can be rationalized.

Claims (3)

[Claims] 1. An epoxy resin composition for laser printing, which comprises an epoxy resin, a curing agent, a filler, and the like, and contains copper carbonate. 2. The epoxy resin composition for laser printing according to claim 1, wherein the average particle size of copper carbonate is 100 μm or less. 3. The epoxy resin composition for laser printing according to claim 1, which contains 0.5 to 20% by weight of copper carbonate with respect to the composition.