JPH0618991B2 - 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 electric and electronic parts, and an epoxy resin for laser printing capable of sharply printing on 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 is used for printing on an electric / electronic component insulating-coated with an epoxy resin composition in order to clearly indicate the characteristics and model number, but the purpose is to rationalize the process. 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 0.0
The time is 1 second or less, which is significantly shorter than the conventional heat-curable or ultraviolet-curable ink which requires several minutes to several tens of minutes for curing.

However, when the insulating coating of the conventional epoxy resin composition was irradiated with a laser, the coating surface was simply roughened, discoloration did not occur, and clear characters or patterns could not be printed.

Recently, it has been found that when a conventional epoxy resin composition contains yellow ferric hydroxide, the color is changed from yellow to brown by laser irradiation (JP-A-62-50360).

However, since ferric hydroxide is yellow, it can be used only for hues such as yellow and orange, and blue or green substrates,
In particular, it has been an issue in the future to apply black laser printing to a light-colored base.

[Problems to be Solved by the Invention]

The present invention has been intensively studied to obtain a resin composition in which a bright color such as blue, red, and green, which has been impossible in the past, is changed to black by a laser. The present invention has led to the completion of the present invention through various researches based on this finding.

It is an object of the present invention 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. It is in.

[Means for Solving the Problems]

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

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

Silver acetate is a colorless crystal, and when heated it is 150-250.
It is deacetic acid at ℃, it changes to silver oxide (I), and it becomes black.

Accordingly, when the epoxy resin composition containing silver acetate is irradiated with a laser in a character or pattern, the resin surface is heated by the thermal energy of the laser, and the silver acetate 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 white, so that black characters and patterns can be clearly printed on a white background.

The grain size of silver acetate used in the present invention has an average grain size of 100 μm.
It is preferably m or less. The reason for this is that when silver acetate is mixed and dispersed in an epoxy resin composition, when the average particle size is 100 μm or more, the surface of the product becomes speckled when coated with electronic and electrical parts, which not only tends to reduce the commercial value of the part. Dispersion is likely to be insufficient, and when irradiated with laser, discoloration does not occur in a portion where silver acetate does not exist, and characters or patterns may be interrupted to make clear printing impossible.

The average particle size is appropriately determined by weight-averaging the particle size distribution obtained by a Coulter counter (manufactured by Nikkaki Co., Ltd.), but may be determined by a measuring method other than the Coulter counter.

The content of silver acetate is preferably 0.5 to 20% by weight. The reason for this is that if the content is 0.5 wt% or less, the degree of color change even when irradiated with laser is small and clear printing cannot be performed, while if it exceeds 20 wt%, the electrical insulating property of the resin composition is reduced. 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 by the present invention usually exhibits white due to the color tone of silver acetate, and thus pigments such as red, blue, green and black can be used in combination.

The resin composition of the present invention may be in any state such as liquid such as casting material, powder such as powder coating material, granule such as molding material and lump.

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 Silver acetate (average particle size 17 μm) 5 〃 crystalline silica powder 50 〃 2 methyl imidazole 1 〃 The above composition was blended and blended with a Henschel mixer, and a kneader After being melt-kneaded in, a powder coating of an epoxy resin composition having an average particle diameter of 60 to 70 μm was obtained by pulverizing with a pulverizer.

Example A powder coating material of an epoxy resin composition having an average particle size of 6 to 70 μm was obtained in the same manner as in Example 1 except that the amount of silver acetate added was changed to 20 parts by weight.

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 silver acetate was changed to 0.1 part by weight.

Comparative Example 2 A powder coating material 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 amount of silver acetate added was changed to 50 parts by weight.

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

Carbon dioxide gas laser (USHIO INC. 40
A 0 type laser mark and an energy density of 6 Joul / cm ² were used to irradiate a laser through a predetermined mask for one millionth of a second to mark the surface of the cured product.

The dielectric breakdown 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 silver acetate. 2. The epoxy resin composition for laser printing according to claim 1, wherein the average particle size of silver acetate 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 silver acetate based on the composition.