JPS5928462B2 - Method of manufacturing laminates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a laminate with less substrate breakage and bubbles.

In the conventional method for producing a laminate, a base material is impregnated or coated with a thermosetting resin, pre-dried, and then stacked, inserted between press platens, and immediately heated and pressurized to form the material.

The base materials used for laminates are generally glass cloth, glass mat, glass nonwoven fabric, paper, cloth, etc. Glass mats and glass nonwoven fabrics are particularly weak in strength when wet and have low density. When used as a laminate, increasing the molding pressure can reduce air bubbles in the laminate and improve electrical performance and moisture resistance, but on the other hand, the flowing resin during molding may wash away the base material. A so-called base material breakage phenomenon occurs, which tends to cause damage to the appearance and properties of the laminate.
On the other hand, if the molding pressure is lowered, the phenomenon of substrate breakage can be prevented, but the number of air bubbles in the laminate increases and the electrical performance deteriorates.
There is a tendency for conditions such as edge humidity to worsen. In this way, conventional laminates using glass mat or glass non-woven fabric as a base material have relatively strong strength in a wet state, compared to laminates using dense glass cloth, paper, fabric, etc. In order to prevent material breakage, the molding pressure must be lowered; therefore, the result is generally a laminate containing many air bubbles. The present invention improves electrical performance and moisture resistance by increasing molding pressure and reducing air bubbles in laminates that use glass mats, glass nonwoven fabrics, etc. as base materials, which have low strength and low density especially in wet conditions. The present invention provides a method for manufacturing a laminate that prevents the phenomenon of substrate breakage.

Glass mat with low strength and low density in wet condition,
In the present invention, in order to increase the molding pressure and prevent the substrate breakage phenomenon, and to produce a good laminate with few air bubbles, the present invention uses Once melted, the viscosity decreases and the flowing thermosetting resin reaches its lowest viscosity. Before the thermosetting resin reaches its lowest viscosity, it is first heated at zero contact pressure until the base material can no longer be washed away, and then air bubbles in the laminate can be reduced. It was then pressurized to the maximum pressure and molded.

In order to explain the principle of the present invention, Fig. 1 shows the change in viscosity of the thermosetting resin over time during laminate molding, and Fig. 2 shows the change in pressure during molding according to the method of the present invention. Shown. That is, as shown in FIG. 1, the resin viscosity during molding first decreases as the temperature of the press heating plate increases, and then increases as the curing reaction occurs. As shown in Fig. 2, in the present invention, before the thermosetting resin reaches its lowest viscosity, the contact pressure is maintained until the viscosity drops to a predetermined value and the base material is no longer washed away (time t), and then the pressure is increased to a predetermined pressure. This is a manufacturing method in which the material is cured as it is. The present invention is capable of preventing base material breakage by heating the thermosetting resin with contact pressure until it reaches a viscosity that does not wash away the base material at a stage before the thermosetting resin reaches its lowest viscosity. Since it is pressurized, the thermosetting resin can be pressurized for a long time while it has a low viscosity, and by degassing sufficiently during that time, it is possible to obtain a laminate with small bubbles and excellent electrical properties. .

The resin viscosity η, at which the thermosetting resin that flows during molding cannot wash away the base material, is not affected by the resin or filler used, but it changes depending on the wet strength of the base material used and the molding pressure. Therefore, it should be determined experimentally.

In addition, in the process where the resin undergoes a curing reaction and its viscosity increases, it is thought that the base material is washed away from the point at which the viscosity reaches η again, causing the base material breakage phenomenon, but in this case, the increase in viscosity is rapid. Thermosetting resins applicable to the present invention, which do not actually cause the substrate breakage phenomenon, include all thermosetting resins such as epoxy resins, phenolic resins, melamine resins, and polyester resins.

Applicable substrates include glass cloth, glass mat, glass non-woven fabric, paper, cloth, synthetic fiber woven fabric, non-woven fabric, etc., all of which are used for laminates, but especially those with high strength in wet conditions. In the case of a laminate using glass mat, glass non-woven fabric, etc., as a base material, which has a low density and a low density, it is possible to provide a laminate with good moisture resistance and electrical properties much more easily than the conventional technology. Next, examples of the present invention will be shown.

Example 1 10 sheets of prepredder obtained by adhering epoxy resin to a glass non-woven fabric base material in a resin amount of 60% and pre-drying were laminated and heated and pressed in a press for 60 minutes to form a 1.6 medium thickness laminate. I made it.

(Hereinafter referred to as invention product 1) At this time, the contact pressure was maintained until the resin viscosity of the prepreg inserted between the press hot platens decreased to 104 poise, and then the pressure was increased to 80 kg/CTII and molded. The temperature of the press hot plate was set at 170° C. during molding. Example 2 9 sheets of prepreg obtained by adhering phenolic resin (30% light tankal added) to a paper base material to a resin amount of 50% and pre-drying were laminated and heated and pressed in a press for 60 minutes.1. A 6mm thick laminate was made.

(Hereinafter referred to as invention product 2) At this time, the contact pressure was maintained until the resin viscosity of the prepreg inserted between the press hot platens reached 105 poise, and then the pressure was increased to 100 k9/d for molding. The press platen temperature was set at 170° C. during molding. Next, a conventional method will be described for comparison.

Conventional Example 1 Ten prepregs similar to those in Example 1 were laminated and heated and pressed in a press for 60 minutes to produce a laminate with a thickness of 1.6 mm.

(Hereinafter referred to as conventional product 1) At this time, immediately after inserting the prepreg between press hot platens, the pressure was increased to 301<9/~ and molding was performed. The press platen temperature was set at 170° C. during molding. Conventional Example 2 10 sheets of prepreg similar to Example 1 were laminated, heated and pressed in a press for 60 minutes, and the result was 1.6 m77! I made a thick laminate.

(Hereinafter referred to as conventional product 2) Immediately after inserting the prepreg between the press hot plates, the pressure was increased to 80 kg/(-Fil) and molded. The press hot plate temperature was set at 170 °C during molding. Conventional Example 3 Implementation Laminate 9 sheets of prepreg similar to Example 2 and press 6 sheets.
A 1.6 mm thick laminate was produced by heating and pressing for 0 minutes.

(Hereinafter referred to as conventional product 3) At this time, immediately after inserting the prepreg between press hot platens, the pressure was increased to 60 k9/d and molding was performed. The press platen temperature was set at 170°C during molding. Conventional example 4 Nine prepregs similar to those in Example 2 were laminated and pressed into six
A 1.6 inch thick laminate was produced by heating and pressing for 0 minutes.

(Hereinafter referred to as conventional product 4) At this time, immediately after inserting the prepreg between press hot platens, the pressure was increased to 100 kg/~ and molded. The press platen temperature was set at 170° C. during molding. Table 1 shows the results of measuring the appearance, insulation resistance, and water absorption of Invention Products 1 and 2 and Conventional Products 1 to 4.

From the results in Table 1, it can be seen that in the case of conventional product 1 with a molding pressure of 30k9/d in the case of a laminate using glass nonwoven fabric as the base material, breakage of the base material can be prevented, but the insulation resistance is low and the amount of water absorbed is large. In the case of conventional product 2 under a molding pressure of 80k9/, the insulation resistance and water absorption were good, but the base material broke. On the other hand, invention product 1 has a molding pressure of 80k9/Crl.
However, it can be seen that the performance is good as there is no breakage of the base material. Furthermore, it can be seen that even in the case of a laminate using paper as the base material, Invention Product 2 has good performance without the base material being cut.

As described above, according to the present invention, even when molding is performed using glass matte, glass nonwoven fabric, etc., which have low strength especially in a wet state and low density as a base material, the phenomenon of base material breakage is prevented and the molding process is performed with few bubbles. laminates can be obtained.

Furthermore, even when paper, which has relatively strong strength in wet conditions and high density, is used as a base material, a large amount of filler may be added to the resin for the purpose of reducing costs, or for the purpose of improving chemical resistance. According to the present invention, even when the amount of resin is increased, the molding pressure can be increased, the phenomenon of substrate breakage can be prevented, and a good laminate with few bubbles can be obtained. Although the present invention is particularly applicable to base materials with low strength and low density in a wet state, it is also effective for base materials with high strength and high density in a wet state, and has no industrial value. It is extremely large.

[Brief explanation of drawings]

FIG. 1 is a curve diagram showing the change over time in the viscosity of the thermosetting resin during laminate molding, and FIG. 2 is a curve diagram showing the change over time in the molding pressure in the present invention.

Claims (1)

[Claims] 1 When prepregs obtained by impregnating a base material with thermosetting resin and pre-drying are stacked and inserted between press hot plates and heated and pressurized, the thermosetting resin, which is once melted by heating, reaches its lowest viscosity. 1. A method for producing a laminate, which comprises first heating with contact pressure until the viscosity reaches a level that does not wash away the base material, and then increasing the pressure to a predetermined pressure, heating, and pressure forming.