JPS6339404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermosetting synthetic resin-impregnated laminate such as an insulating board, a copper-clad laminate, or a laminate tube, and more particularly, the present invention relates to a method for producing a thermosetting synthetic resin-impregnated laminate such as an insulating board, a copper-clad laminate, or a laminate tube. (abbreviated simply as resin) relates to a method of impregnating varnish. Resin-impregnated laminate products are generally made by impregnating a base material such as paper, organic or inorganic natural fibers, glass fibers, chemical fibers, non-woven fabrics, etc. with resin varnish, drying it to obtain prepreg, and stacking the required number of prepregs and heating them. Manufactured under pressure. When impregnating a base material with resin varnish, the resin must be applied uniformly to the base material, that is, the resin must be applied in equal amounts to the front and back surfaces of the base material, up to the center of the thickness, and the resin must be applied to each part of the base material. The amount distribution also needs to be uniform. For this reason, the resin varnish is carefully controlled so that the impregnation of the resin varnish into the base material is improved and so that a uniform amount of the resin varnish is deposited on the base material. These impregnating properties and uniform amount of adhesion are mainly adjusted by the viscosity and resin concentration of the resin varnish. If the impregnating property is not sufficient, the laminate will have poor insulation properties and poor punching properties, and if a uniform amount of resin varnish is not applied to the base material, the thickness of the laminate may not be accurate and the properties may not be uniform. Both have serious flaws. Conventionally, in order to improve the impregnability of the base material, resin varnish is diluted with a solvent to achieve the desired viscosity.
Because the base material is impregnated with resin varnish, some of the solvent evaporates during the coating and impregnation process, increasing the viscosity of the varnish.If the solvent is not replenished, the viscosity reaches the upper control limit. Since the viscosity was adjusted by replenishing the solvent in the process, the resin content of the resin-impregnated base material varied. The present invention has been made in view of these points, and includes a method for manufacturing resin-impregnated laminates in which a base material is impregnated with resin varnish, dried to obtain a prepreg, and the required number of prepregs are stacked and heated and pressurized. By maintaining the resin varnish at a constant temperature of 35 to 60℃ and adjusting the viscosity to a specified level without intermittently adding large amounts of solvent to the resin varnish, it is possible to eliminate variations in the resin content of the resin-impregnated base material and create a homogeneous product. The present invention relates to a method of manufacturing a laminate. That is, the present invention provides the resin varnish with the desired viscosity required to improve its impregnating property by heating and maintaining the resin varnish at a constant temperature of 35 to 60°C at the stage of impregnating the base material with the resin varnish. It is. The viscosity of the resin varnish required from the viewpoint of impregnating properties varies depending on the type of base material, resin, and solvent, but in general
30-1000CP is preferred. The viscosity of a resin varnish depends on temperature and concentration, and in the present invention, the resin varnish is maintained at a constant temperature of 35 to 60°C. When a resin varnish is heated and maintained at a constant temperature of 35 to 60°C, the temperature is higher than that of a resin varnish at room temperature, so if the concentration is constant, the former evaporates more solvent, but in the present invention, the desired temperature is The amount of solvent required to achieve the viscosity of Although it depends on the temperature, the amount of solvent evaporated is slightly larger in the former case than in the case held at room temperature. However, depending on the resin, type of solvent, and temperature,
For a desired viscosity, the amount of solvent saved due to increased temperature (because the resin varnish can be made highly concentrated) typically far exceeds the amount of solvent evaporated due to increased temperature. If the temperature of the resin varnish is too high, the reaction rate of the resin will increase and the variation in gel time will increase, so the optimum temperature is determined from this point as well.
If the resin has a long gel time, it can be heated to a fairly high temperature. The concentration of the resin varnish is determined by the amount of resin attached to the base material, but a resin varnish with a resin content of 40 to 80% is generally used. Next, the present invention will be further explained with reference to drawings showing one embodiment of the present invention. A strainer 3 is installed at the outlet between the head tank 1 and the impregnation tank 2 where the varnish stock solution and solvent are continuously supplied.
The circulating fluid is circulated by a pump equipped with a pump, and the circulating fluid is heated to a constant temperature above room temperature. As a heating device,
A heater provided in the impregnation tank, a jacket, a heat exchanger 4 provided at the outlet of a pump, etc. are used. The head tank 1 is kept at a constant temperature, and the viscosity is measured here, and a diluting solvent is continuously added to keep the viscosity constant. As the solvent, a general solvent used for resin varnish for impregnation is used. For mixing with this diluting solvent, it is necessary to either stir the head tank or install a line mixer or the like between the head tank and the impregnating tank. By adding a solvent to part of the circulation system between the head tank 1 and the impregnation tank 2 and diluting it continuously, the viscosity of the impregnating resin varnish can be kept constant even if the evaporation of the solvent varies. It will be done. When the temperature is raised in this way, the resin hardens, so it is necessary to keep the high temperature circulation rate constant and control the curing reaction rate; therefore, the circulation rate cannot be maintained at a constant level. It becomes necessary. To do this, the resin varnish is sent from the head tank to the impregnation tank by overflow, and the resin liquid is sent by controlling the liquid level in the impregnation tank, or the resin varnish is taken out from the impregnation tank by overflow and sent to the head tank, and the liquid level in the head tank is controlled. Either method of feeding the resin liquid under control is required. If the amount of resin varnish held in the circulation system, temperature, and viscosity can be kept constant through continuous circulation in this way, even if curing progresses, the circulation system of the impregnation tank and head tank will act like a continuous stirring tank, which will prevent curing. Since the degree is constant, it is not a problem that the curing progresses as long as the amount of resin that has not yet undergone curing reaction is fed. When resin varnish is kept at a fairly high temperature, evaporation of the solvent can be significantly reduced by making the impregnation tank and head tank nearly airtight. Furthermore, by sealing the entrance and exit of the base material 5 with a roll or the like and sealing the impregnating tank and head tank, it becomes possible to raise the temperature considerably. In the figure, 6 is a resin varnish stock solution tank, 7 is a solvent tank, 8 is a hot water tank, and 9 is a squeeze roll. The temperature and viscosity of the resin varnish are kept constant in the circulation system, but depending on the purpose of the final product, the temperature can be adjusted to ±3°C, the viscosity can be adjusted to ±0.2 poise, or ±0.2 poise.
A variation of approximately ±5% in the retained amount is acceptable. Note that the temperature varies by 10 to 20 degrees Celsius depending on the location of the heating location in the entire circulatory system, but the steady state is not a problem, and the above-mentioned variations are for the same location. The base material can be paper such as kraft paper, linter paper, glass cloth, glass nonwoven fabric, polyester cloth, polyester nonwoven fabric, carbon fiber cloth, asbestos cloth, asbestos nonwoven fabric, or organic or inorganic natural fiber, glass fiber, or chemical fiber. Cloth and non-woven fabric can be used. Further, as the resin, common resins for laminated products such as phenol resin, epoxy resin, polyester resin, melamine resin, and silicone resin are used. As explained above, according to the present invention, there is no variation in the amount of resin attached to the base material, making it possible to manufacture a homogeneous and stable laminate product, and reducing the amount of solvent used. Furthermore, the moving speed of the base material can be increased, and productivity can be improved. Example: Using the impregnation equipment shown in the drawing, the temperature was 40℃ and the viscosity was
100CP, a phenolic resin varnish with a resin concentration of 60% and methanol as a solvent is impregnated into a paper base material, and the usual method is used (150℃, 100Kg/cm ² , 1 hour heat and pressure).
A copper foil-clad laminate was manufactured. Note that the resin varnish was heated using steam. In this case, the variation in the amount of resin attached to the base material is
Compared to the conventional method (diluting resin varnish with a solvent to achieve the desired viscosity), the ratio of impregnated base material outside the weight standard is 1/1
2, the amount of solvent used was reduced by 30% compared to the conventional method, and the moving speed of the substrate was increased by 25% compared to the conventional method due to the reduction in solvent and variation. The properties of the obtained copper-clad laminate are shown in the table below. 【table】

[Brief explanation of the drawing]

The drawing is a system diagram of an impregnating apparatus showing an embodiment of the present invention. Explanation of symbols, 1... Head tank, 2... Impregnation tank, 3... Strainer, 4... Heat exchanger, 5...
... Base material, 6 ... Resin rinse stock solution tank, 7 ... Solvent tank, 8 ... Hot water tank, 9 ... Squeeze roll.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a thermosetting synthetic resin-impregnated laminate in which a required number of prepregs impregnated into a base material with a thermosetting synthetic resin varnish and dried are superimposed and heated and pressed,
The resin varnish is applied at the stage of impregnating the base material with the resin varnish.
A method for producing a thermosetting synthetic resin-impregnated laminate product, which is characterized by heating and maintaining at a constant temperature of 35 to 60°C. 2. Circulate the resin varnish between the impregnation tank and the head tank to which the resin varnish stock solution and solvent are continuously supplied so that the amount of resin varnish held in the circulation system is constant, and maintain the viscosity of the resin varnish constant. A method for producing a thermosetting synthetic resin-impregnated laminate product according to claim 1.