JPS634575B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a laminate. Conventionally, laminates are made by impregnating a paper base material with a phenolic resin varnish consisting of a phenolic resin and a solvent, drying and removing the solvent to form a B-stage prepreg, and then laminating a plurality of prepregs and pressing them under heat and pressure ( It was manufactured by press molding). However, recently, it has been desired to provide a laminate with even better performance. Therefore, a method of manufacturing a laminate using an unsaturated resin such as an unsaturated polyester resin, which has excellent properties (insulating properties, etc.) of the resin itself, has been considered. For example, an unsaturated polyester resin (liquid) is made using unsaturated polyester and a liquid cross-linking agent (styrene, etc.), this is impregnated into a paper base material, and multiple sheets of this impregnated base material are stacked and laminated by passing them through a roll. At the same time, excess resin is squeezed out, and then the laminate is manufactured by heating under no pressure. In this case, the unsaturated polyester resin (liquid) suddenly changes from the A stage to the C stage without passing through the B stage, so if press molding is performed like when using phenolic resin, the liquid resin will change when pressurized. It oozes out from the paper base material, preventing smooth molding. Therefore, a method is adopted in which the laminate is heated under no pressure. However, by doing this, the laminate can be manufactured continuously (press molding is done in batches). Also,
In this case, since the unsaturated polyester resin (liquid) is made from the unsaturated polyester and the crosslinking agent, there is no need to use a solvent unlike when making phenolic resin varnish, and it is also effective in terms of resource and energy saving. Are better. However, since the laminate thus obtained has high water absorption, its electrical performance deteriorates after absorbing moisture, making it unsuitable for use as an electrical insulating board. Furthermore, the punching processability is poor, and when a laminate is punched, it has the disadvantage that delamination occurs. In this way, the reason why it is not possible to obtain a laminate with excellent performance even when using unsaturated polyester resin, which has excellent performance itself, is due to the lack of affinity between unsaturated polyester resin (liquid) and paper base material. This is thought to be due to this. Therefore, in order to eliminate the above-mentioned drawbacks of laminates obtained using unsaturated resins such as unsaturated polyester resins, the inventors developed melamine resins and phenolic resins, which are known to have water absorption improving effects. The base material was pretreated with a normal water absorbency improving treatment resin (hereinafter referred to as treatment resin) having a hydrophilic group such as . Although water absorption was improved in this way, punching workability was not improved at all. Therefore, as a result of further research using various resins, the inventors pre-treated the base material with commonly used treatment resins such as melamine resin and phenolic resin and epoxy resin, and The present inventors have discovered that when the content of the resin in the base material is set within a certain range, both water absorption and punching workability are improved, and this invention has been completed. That is, the present invention is a method of impregnating a base material with an unsaturated resin and manufacturing a laminate using this resin-impregnated base material, the base material containing a processing resin and an epoxy resin, If the content of the processing resin in the base material is A, and the content of the epoxy resin in the base material is B, the content A, B
The gist thereof is to use a base material in which the following formulas are set: 25>A+B>5% by weight, A>4% by weight, and B>1% by weight. As the base material used in this invention, a cellulose base material is usually used. Among these, paper base materials such as kraft paper, linter paper, and kraft linter mixed paper are mainly used. However, the material is not limited thereto, and a wide variety of commonly used base materials can be used. The processing resin to be included in the base material is as follows:
Resins commonly used to improve water absorption, such as melamine resin, phenolic resin, urea resin, benzoguanamine resin, acetoguanamine resin, and polymethylol acrylamide, are used. In addition, the epoxy resin contained in the base material together with the processing resin is not limited in any way,
Common epoxy resins are used. Note that, in the present invention, epoxy resins that contain a curing agent and a curing accelerator are also included. The unsaturated resin to be impregnated into the base material containing the treatment resin and epoxy resin includes, but is not limited to, unsaturated polyester resin. Resin, vinyl ester resin, etc. are used. In this invention, the unsaturated polyester resin refers to an unsaturated polyester diluted with a crosslinking agent (crosslinking monomer). The same applies to diallyl phthalate resin and vinyl ester resin. Examples of such crosslinking agents include styrene, tert-butylstyrene, chlorostyrene, divinylbenzene, diallyl phthalate, methyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, etc. Used alone or in combination. In the present invention, a laminate is manufactured in the following manner using the raw materials as described above. That is, first, ordinary processing resins such as melamine resin, phenolic resin, urea resin, etc. and epoxy resin are mixed with water and epoxy resin, respectively.
Methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, toluene,
It is diluted with trichlorethylene, chloroform, dioxane, tetrahydrofuran, etc. singly or as a mixture, and the base material is impregnated with these and dried for pretreatment. The method of impregnation does not matter. It may be immersed or coated. By performing the pretreatment in this manner, the treatment resin and epoxy resin are contained in the base material. In this case, the content of the processing resin with respect to the base material exceeds 4% by weight (hereinafter abbreviated as "%"), and the content of the epoxy resin with respect to the base material is 1%.
It is necessary to adjust the content so that the total content of both resins with respect to the base material is more than 5% and less than 25%. That is, when the treatment resin is 4% or less relative to the base material, the improvement in water absorption is insufficient, and when the epoxy resin is 1% or less relative to the base material, the improvement in punchability is insufficient. In addition, if the total amount of both resins is less than 5% of the base material, the improvement in water absorption and punching properties will be insufficient;
This is because even if it exceeds the above limit, no further improvement in the effect is observed, which is undesirable from the viewpoint of the occurrence of folding of the base material. Next, the base material containing the processing resin and epoxy resin through the above pretreatment is impregnated with the above-mentioned unsaturated resin. In this case, the viscosity of the unsaturated resin is preferably set to 500 to 4000 centipoise by adjusting the amount of crosslinking agent added. In addition, 0.5 to 2% of the usual thermal polymerization initiators listed below are usually added alone or in combination to this unsaturated resin. Thermal polymerization initiator: benzoyl peroxide, methyl ethyl ketone peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl perbenzoate, dicumyl peroxide, etc. Furthermore, an accelerator such as a naphthenic acid metal salt or dimethylaniline is added to the unsaturated resin as necessary. A predetermined number of base materials impregnated with the unsaturated resin in this manner are stacked in a predetermined number and rolled over a roll to form a laminate, and heated under no pressure to form a laminate. In this case, the above-mentioned base material may be used in combination with a base material that has not been pretreated with the treatment resin or epoxy resin and is impregnated with an unsaturated resin, or if necessary, the base material may be impregnated with metal foil. It may be layered on the base material. In this way, the laminate referred to in the present invention includes a metal foil-clad laminate. The thus obtained laminate has improved water absorption and punching workability, and has excellent performance. In order to manufacture a laminate in the manner described above, the present invention provides a laminate with improved water absorption and punching workability, and excellent performance while achieving resource and energy savings (because no solvent is used). It can be manufactured continuously. Next, examples will be described together with comparative examples. [Examples 1 to 5, Comparative Examples 1 to 3] Kraft paper with a thickness of 254μ (10 mils) was impregnated with the epoxy resin and treatment resin shown in the table below.
The kraft paper was pretreated by drying at 50° C. for 5 minutes, and the kraft paper contained an epoxy resin and a treatment resin in the amounts shown in the table, respectively, based on the kraft paper. Next, five sheets of pre-treated kraft paper are impregnated with unsaturated resin of the composition shown in the table below, then both sides are covered with polyester film, and the sheets are laminated by passing between rolls with a clearance of 1.6 mm. did. The resulting uncured laminate was then placed in a dryer set at 120°C and cured to form a laminate. The performance of the obtained laminate is summarized in the following table. As is clear from the table,
The laminates obtained in the examples differ from the laminates obtained in the comparative examples in terms of punching workability, water absorption,
All insulation properties are excellent. 【table】

Claims (1)

[Claims] 1. A method of impregnating a base material with an unsaturated resin and manufacturing a laminate using this resin-impregnated base material, the base material containing a resin for water absorption improvement treatment and an epoxy resin. If the content of the resin for water absorption improvement treatment in the base material is A, and the content of the epoxy resin in the base material is B, then the contents A and B are 25>A+B>5% by weight A>4% by weight % B > 1% by weight. 2. The method for manufacturing a laminate according to claim 1, wherein the base material is a cellulose base material. 3. Claim 1 or 3, wherein the resin for water absorption improvement treatment is at least one resin selected from the group consisting of melamine resin, phenolic resin, urea resin, benzoguanamine resin, acetoguanamine resin, and polymethylol acrylamide. 2
Method for manufacturing the laminate described in Section 1. 4. The laminate according to any one of claims 1 to 3, wherein the unsaturated resin is at least one resin selected from the group consisting of unsaturated polyester resin, diallyl phthalate resin, and vinyl ester resin. manufacturing method.