JPH0121770B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a prepreg used for manufacturing a laminate, and more particularly, to a method for impregnating a base material with a resin varnish. Conventional prepreg has a base material 1 as shown in Figure 1.
is immersed in resin varnish 2, passed through it, squeezed to a certain amount with squeeze roll 3, and heated to 120 to 180 in the drying room 4.
℃ for 1 to 5 minutes and cut into predetermined dimensions. 5 is the manufactured prepreg. However, in this method, the amount of resin deposited was adjusted by adjusting the resin varnish concentration and was also adjusted to a constant amount using a squeeze roll. Therefore, the resin varnish used is impregnated in a very diluted state with a concentration of 10 to 60% (same as below weight%), and the solvent used increases the cost of prepreg products and is difficult to dispose of the material scattered in the drying room. It was expensive. In the present invention, a resin varnish is one in which a thermosetting resin such as a phenol resin, an epoxy resin, or a polyester resin is dissolved in a solvent such as acetone, methyl ethyl ketone, toluene, or alcohol. When applying resin varnish at a high concentration of 60 to 80%, it is possible to apply it using conventional methods, such as the dipping method shown in Figure 1, but in that case, the amount of prepreg applied will be lower than the paper and fibers that are the base material. Since the amount of adhesion increases in proportion to the amount of voids, if the required amount of adhesion is 40 to 50%, a considerable amount must be removed with a squeeze roll or the like. If the amount of resin is reduced to an appropriate amount using a squeeze roll or the like, meandering will occur due to paper breakage and imbalance between the right and left sides, making it impossible to perform actual work. Also, if a high-concentration resin varnish with a concentration of 60 to 80% is applied using the kiss coating method as shown in Figure 2, the resin tank 6
It is not suitable because it has a large capacity and the amount of application varies widely due to changes in resin varnish temperature and concentration. In Figure 2, 7
is a guide roll, and 8 is a kiss roll. The present invention was made in view of these points, and includes a resin varnish with a resin concentration of 60 to 80% on the base material.
It is characterized in that it is applied to one side of the substrate from above and then dried. Figure 3 shows an example of a method in which a resin varnish with a resin concentration of 60 to 80% is applied to one side of the base material from above the base material. The resin varnish is stored on the upper surface of the base material using a weir plate and a cut bar, and the resin varnish is applied to the base material while adjusting the coating film thickness of the resin varnish using the cut bar. In FIG. 3, 1 is a base material, 9 is a guide roll, 10 is a compression roll, 11 is a weir plate, 12 is a cut bar, and 13 is a high concentration resin varnish. The base material 11 is sent by a guide roll 9 and the thickness of the base material is reduced by a compression roll 10.
The compressed base material is compressed by 10 to 50% by volume (heating the guide roll 9 and compression roll 10 will improve the effect). The high-concentration resin varnish is applied to one side of the substrate from above, with the thickness of the deposited film being adjusted by the gap between the cut bar 12 and the guide roll 9.
The most suitable viscosity of the resin varnish is 200 to 5000 centipoise, and a varnish with too low a viscosity may flow from both ends of the weir plate and may also stick to the guide roll 9 through the base material. In this case, a second weir plate is installed at right angles to both ends of the weir plate, and the weir plates 11, 2
It is preferable that a rectangular space having a constant slit width is formed by the second cutter plate and the cut bar 12, and the resin varnish is supplied into this rectangular space. If the second plate is attached inside the width of the base material, the resin varnish can be prevented from being applied to both ends of the base material, for example, 5 to 20 mm. In that case, you can leave a 5-20mm gap between both ends of the paper cloth and coat only the necessary areas.This is because the edges must be cut off by 5-20mm during the finishing process in the production of laminates, so the base material Even if the end portions are not coated with resin varnish, the yield can be improved by 5 to 20 mm of resin varnish. In addition, in this method, if uneven penetration occurs with a normal base material, even penetration can be achieved by thinning the thickness (density) of the paper cloth using a compression roll and reducing the amount of voids in the paper cloth. Figure 4 shows another method of applying a resin varnish with a resin concentration of 60 to 80% to one side of the base material from above the base material. wood,
14 is a guide roll, 15 is a coating roll, 16 is a metering roll, and 17 is a weir plate. The high concentration resin varnish 13 is accumulated on the coating roll 15 by the metering roll 16 and the weir plate 17. The high-concentration resin varnish 13 is transferred to a base material such as paper cloth, which is transferred to a base material such as paper cloth, which is passed through a guide roll 14, with a film thickness of a certain amount adjusted by a cap of a metering roll and a coating roll 15, and a certain amount of resin varnish is applied. Prepreg is manufactured by applying it to paper cloth and drying it. Adjustment of the amount of resin attached to the prepreg is determined by the thickness and density of the base material used, such as paper cloth, to be impregnated. Therefore, in the case of the roll transfer method shown in Figure 4, sufficient precision and maintenance between rolls must be maintained. In addition, the accuracy between rolls is controlled to prevent fluctuations in the amount of resin deposited, safety between rolls, and non-uniform film thickness at high speeds. As shown in FIGS. 3 and 4, the cut bar 12 and the weir plate 11 or the metering roll 1
6 and the weir plate 17, the high concentration resin varnish 13 is accumulated on the upper surface of the base material or on the coating roll.
It is preferable to apply heat to lower the viscosity of the high concentration resin varnish. In this case, heating is preferably from 35°C to 50°C. By lowering the viscosity, the varnish can more easily penetrate between the paper fibers and improve its wettability to the fibers. To apply heat to the high concentration resin varnish, for example, in FIG. 3, the guide roll 9 and the cut bar 12, and in FIG.
5. This can be carried out by providing high-temperature heat medium (steam, hot water) piping in one or both of the metering rolls 16 and using these as a heat roll.
FIG. 5 is a perspective view of the guide roll 9 and cut bar 12 shown in FIG. 3 with heat medium piping 18 installed therein. In FIG. 3, the highly concentrated resin that the guide roll 9 and cut bar 12 come into contact with in a cold state removes heat from the base material such as varnish or paper, increasing the viscosity of the varnish and having an adverse effect. These rollers pass through the heat medium to prevent the varnish from increasing in viscosity and to maintain the time required for the high concentration resin varnish to penetrate into the base material such as paper. By varying the amount of heat given to the high-concentration resin varnish, the varnish viscosity can be adjusted to a required value regardless of the ambient temperature. As explained above, the present invention is a prepreg manufacturing method characterized by applying a resin varnish with a resin concentration of 60 to 80% to one side of the base material from above the base material and then drying it. In the present invention, as the base material, not only paper but also glass nonwoven fabric, glass cloth, and synthetic fiber cloth or nonwoven fabric can be used. resin concentration
When applying a 60-80% high concentration resin varnish to one side of a substrate from above, it can be applied not only from directly above the substrate, that is, vertically, but also from a 45° angle. . Further, drying is performed by heating at 80 to 180°C for 20 seconds to 5 minutes. In the present invention, when producing prepreg by impregnating and drying a resin varnish on a base material, a resin varnish with a high concentration of 60 to 80% can be used, and the amount of solvent used is small, which improves the efficiency of prepreg production. is achieved. Example 1 After pre-treating the paper base material with a water-soluble phenolic resin, it was impregnated with a 70% varnish of tung oil-modified phenolic resin using the coating method shown in Figure 3 and dried at room temperature so that the resin coverage was 50%. Prepreg was obtained. The properties of a 1.6 mm laminate obtained by laminating 8 sheets of this prepreg under heat and pressure are shown in the attached table. Example 2 After pre-treating a Kotonlinta paper base material with a water-soluble phenolic resin, a varnish of 65% varnish concentration of tung oil-modified phenolic resin was applied using the coating method shown in Figure 4 to reduce the amount of resin attached.
A prepreg was obtained by impregnating and drying at room temperature to a concentration of 50%. The properties of a 1.6 mm laminate obtained by laminating 8 sheets of this prepreg under heat and pressure are shown in the attached table. Example 3 After pre-treating a paper base material with a water-soluble phenolic resin, a varnish of 75% varnish concentration of tung oil-modified phenolic resin was applied using the coating method shown in Figure 3 to reduce the amount of resin attached.
A prepreg was obtained by heating the varnish to 40°C and impregnating and drying it so that the concentration was 50%. This prepreg is 8
The properties of the 1.6 mm laminate obtained by laminating the sheets under heating and pressure are shown in the attached table. Comparative Example After pre-treating a Kotton Rinter paper base material with a water-soluble phenolic resin, it was impregnated with a 50% varnish concentration of tung oil-modified phenolic resin varnish using the coating method shown in Figure 1 and dried at room temperature so that the resin coverage was 50%. A prepreg was obtained. The properties of a 1.6 mm laminate obtained by laminating 8 sheets of this prepreg under heat and pressure are shown in the attached table.

【table】

[Table] As is clear from this table, in the present invention, even if a high concentration resin varnish of 60 to 80% is used, the laminate obtained using a conventional low concentration resin varnish and each In terms of characteristics, it is possible to obtain something comparable in no way.

[Brief explanation of drawings]

Figures 1 to 4 are simplified sectional views showing the prepreg manufacturing method, with Figures 1 and 2 being the conventional method, and Figures 3 and 4 being the same.
The figure shows the invention. FIG. 5 is a perspective view showing the guide roll and cut bar shown in FIG. 3 in a heated state. Description of symbols, 1...Base material, 2...Resin varnish, 3
... Squeeze roll, 4 ... Drying room, 5 ... Prepreg, 6 ... Resin tank, 7 ... Guide roll, 8 ... Kiss roll, 9 ... Guide roll, 1
0... Compression roll, 11... Weir plate, 12... Cut bar, 13... High concentration resin varnish, 14... Guide roll, 15... Coating roll, 16
...Metaling roll, 17...Weir plate, 18...
Heat medium piping.

Claims (1)

[Claims] 1. A resin varnish with a resin concentration of 60 to 80% is applied to the base material,
A prepreg manufacturing method characterized by coating one side of a base material from above and then drying. 2 While moving the base material in the horizontal direction, resin varnish is collected on the upper surface of the base material using a weir plate and a cut bar, and the resin varnish is applied to the base material while adjusting the coating film thickness of the resin using the cut bar. A method for producing a prepreg according to claim 1. 3. The prepreg manufacturing method according to claim 1 or 2, which comprises heating the resin varnish. 4. The prepreg manufacturing method according to claim 1, 2, or 3, characterized in that the resin varnish is applied to the base material except for both ends thereof. 5. A prepreg manufacturing method, which comprises compressing the base material to reduce the amount of voids, then applying a resin varnish with a resin concentration of 60 to 80% to one side of the base material from above the base material, and drying.