JPH02298520A - Prepreg and production thereof - Google Patents

Abstract

PURPOSE:To obtain a cloth prepreg having excellent appearance without any voids in formed laminated boards by shaping continuous recessed parts on the surface of a cloth-reinforced thermosetting type resin prepreg with a roll having uneven parts. CONSTITUTION:The objective prepreg obtained by shaping continuous recessed parts on the surface of a cloth-reinforced thermosetting type resin prepreg with a roll having uneven parts. Furthermore, the depth of the recessed parts in the prepreg is preferably 20-50% based on the thickness of the prepreg and the distance of both sides in the recessed parts is preferably 1-3mm. The total surface area ratio of the recessed parts is preferably 30-70%.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a novel textile fiber-reinforced thermosetting resin prepreg (hereinafter abbreviated as "cross prepreg") with excellent moldability and a method for producing the same.

<Conventional technology> Thermosetting resins such as epoxy resins are combined with carbon fibers,
Cross prepreg, which is semi-cured by impregnating reinforcing fabrics made of aramid fibers, etc., is used in industrial materials such as leaf springs and structural materials, sports leisure equipment such as fishing rods and golf shafts, and more recently in aircraft, automobiles, ships, etc. Many books have come to be used as materials.

Molding of the cross prepreg is carried out by methods such as compression molding using a mold, autoclave molding using a Kakuda kettle, and normal pressure vacuum bag molding. A common technical problem in these moldings is how to eliminate voids in the molded cured product and pinholes that occur on the surface of the molded product.

As shown in FIG. 2, voids can be divided into two types: intralayer voids that occur within the prepreg layer, and interlayer voids that occur between the blib V layers.

What does not have a particularly negative effect on the mechanical properties of the molded product are the relatively large interlayer voids that occur.

The causes of voids include moisture contained in the prepreg resin, volatile matter from the solvent, or bubbles from air remaining in the resin, but the biggest cause of interlayer voids is between the prepreg layers during lamination. It is thought that this is an air pocket that was taken in and left behind. Therefore, when trying to obtain a large molded product with a large number of laminated layers in a void-free state using an autoclave, etc., it is necessary to make holes in each laminated ply with the tip of a pin or a cutter blade to expel the air taken in during lamination. Wow, it was necessary to remove the air by hanging the bag with plastic film or the like every few briars and vacuum degassing. In addition, pinholes that occur on the surface of molded products are thought to have the same mechanism as voids between prepreg layers, and in this case, air is left behind between the prepreg and the mirror-like substrate used when laminating it. Conceivable.

<Problem to be solved by the invention> Deaeration work in autoclave molding requires a great deal of labor and time, and in reality, air pockets between the layers cannot be removed completely, resulting in the formation of interlayer voids. There are also many.

If the surface tackiness is weakened at this time, air pockets trapped between KNs will occur less frequently during lamination, making it easier to obtain a good void-free molded product. However, due to its weak tackiness, it is difficult to stack layers when forming curved surfaces, etc.
There are problems such as books that are laminated and one that peels off easily. or,
The same applies to pinholes on the surface of the molded product that occur during vacuum forming. In other words, the desired characteristics of a cross prepreg are that it has appropriate tackiness and good degassing properties during lamination. The inventors of the present invention arrived at the present invention as a result of extensive research into cross prepregs that have both of these two characteristics of tackiness and degassing properties.

Means for Solving the Problems The gist of the present invention is a textile-reinforced thermosetting resin prepreg having continuous recesses on at least one surface, and a method for producing the same.

The present invention will be explained below with reference to the drawings.

FIG. 1(A) is a schematic cross-sectional view of the prepreg of the present invention after lamination, and FIG. 1(B) is a schematic diagram of the prepreg of the present invention supported on release paper.

The prepreg of the present invention has four continuous parts on its surface as shown in Fig. 1(B), so when the prepregs are stacked as shown in Fig. 1(A), the concave part becomes an air passage. This will prevent air pockets from forming.

Even during molding, these grooves become passageways for the resin containing air and volatile matter to move, and the fibers around the grooves move in the lateral direction, ultimately resulting in a good molded product with no interlayer voids. However, the shape of the recess is not limited to that shown in this figure.

In addition, although the example shows a prepreg with unevenness on only one side, the same effect can be expected with a prepreg with unevenness on both sides.

FIG. 3 shows an example of air pockets that occur when a conventional type of prepreg is layered. When the air pocket shown in FIG. 3(A) is viewed from the x-x' cross section in the figure, it is shown in a schematic diagram as shown in FIG. 3(B). Even if the air pockets shown in FIG. 3 are pressed down a little, they do not disappear, and some of them remain even during molding and pressurization, and remain in the molded product as interlayer voids.

The prepreg of the present invention has significantly enhanced surface tackiness, and as long as the recesses are not blocked, a laminate with almost no air pockets can be obtained by simply pressing and laminating lightly by hand or with a roller, and there are almost no interlayer voids. It is possible to obtain a molded product with good quality. Moreover, when the surface having irregularities during lamination is made to face the substrate surface for lamination, a similar effect can be obtained, and a good molded article without pinholes on the surface of the molded article can be obtained.

The depth of the recessed portion of the prepreg of the present invention is preferably 15 to 70%, more preferably 20 to 50%, of the thickness of the prepreg. Also, depending on the size and depth of the recess,
The distance between both sides of the recess is α5 to 5 m, more preferably 1 to 3 ridges is 0, and the area ratio of the recess to the whole depends on the depth K of the four parts, but it is more preferably 30 to 95 cm.
70 section is good. If the recesses are too shallow, they will close immediately during lamination and the effects of the present invention cannot be fully exhibited, and if the recesses are too deep, traces of the grooves may remain on the surface of the molded product, which is undesirable.

If the distance between the side surfaces of the four parts is too small, it will be difficult to shape and the clogging will occur more frequently during lamination, resulting in a prepreg that is not suitable for the present invention.If it is too large, the sunken part of the recess will come into contact with the prepreg laminated thereon. On the contrary, it creates air pockets and leads to frequent interlayer voids. If the area ratio of the recesses is too small, it will be impossible to obtain the required air flow, and clogging will occur frequently during lamination, resulting in prepregs that are not suitable for the present invention. On the other hand, if the area of the concave portion is too large, the tackiness between the prepregs or between the base and the prepreg will weaken, making it difficult to stack them, and even if they are stacked, they will peel off easily.

The prepreg manufacturing method of the present invention is a roll having uneven parts (
This is a method of pressing a concavo-convex roll (hereinafter abbreviated as a concavo-convex roll) onto the prepreg surface. In that case, the grooves may be shaped online during the prepreg impregnation process, or with a prepreg machine). Hour 7.7e2. picture,. hot water. hot water. 4
Off-line shaping with post-processing at 6°-2 may also be used. FIG. 4 shows an example of a prepreg manufacturing apparatus of the present invention using an online forming method, and FIG. 5 shows an example of surface processing of a textured roll suitable for use in the present invention.

In Fig. 4, 1 is a roll for unwinding the fabric, 2 is a hot melt resin film made of double-sided silicone release paper coated with thermosetting resin, 3 is a winding shaft for a polyolefin film for the cover of the hot melt resin film, and 4 is Dancer roll for tension control, 5 is polyolefin film for cover used to prevent the roll from being contaminated with resin, 6 is preheating plate heater for impregnation, 7, 8, 9 is heating nip roll for impregnation, 10 is cooling A traction nip roll also serves as a roll, 11 is a preheating plate heater for forming, and 12 is an uneven roll. This roll and 1
The prepreg is nipped between two preheating plates and shaped. Reference numeral 13 indicates a winding axis of the polyolefin film for the cover, and 14 indicates a winding axis of the product.

When forming recesses in prepreg using the apparatus shown in Figure 4, the temperature of the preheating plate 11 is important, and it also depends on the nip pressure, resin viscosity, resin content of the prepreg, prepreg thickness, production speed, etc. 35 to 85 °C, more preferably 40 to 60 °C, is a good value. If the preheating temperature for molding is too high, the resin will be squeezed out, a resin pool will be formed, and it will flow sideways, leading to uneven resin content. Also, if it continues to be low, molding becomes difficult.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1. Comparative Example 1 A plain weave cloth of 200 t/m'' was obtained by using untwisted 3-strand yarn obtained by bundling carbon fibers with a diameter of 8 μm as the warp and weft.

The above plain weave cloth and 250°C curing type Epoquine resin were coated using the prepreg manufacturing apparatus shown in Fig. 4 and a grooved roll having grooved grooves as shown in Fig. 5 (A). Molded with silicone double-sided release paper, fiber basis weight 20097m! , a cross prepreg with a target resin content of 45wt4 was produced. For comparison, prepreg was also prepared by opening the nip of the grooved roll and subjecting it to a pre-station type treatment. Both prepreg surfaces were measured using an optical roughness meter (
KEY ACE ■High precision laser displacement meter Do-2000-[
Table 1 shows the groove depths measured in 01o). Each of these prepregs was heated to 100 ml without degassing in the middle as shown in Figure 6.
After laminating the braai, hang a nylon bag, 75511111
Autoclave molding was performed according to the curing schedule shown in FIG. 7 while vacuuming at a vacuum level of 1 Hg or more.

The molded products are arranged on the a-32 plane, b-b' plane, and
After cutting at five locations: c-c' plane, a-a' plane, and e-e' plane, and polishing the cut surfaces, the number of interlayer voids larger than lsoμ was counted using an optical microscope, and the results are shown in Table 1. It is also shown in . The thickness of the prepreg in Table 1 was measured using a dial gauge type cloth thickness meter.

Example 2. Comparative Example 2 The same prepreg used in Example 1 was used to conduct an experiment regarding pinholes on the surface of the molded article.

The stainless steel mold shown in FIG. 6 was mirror-finished, and vacuum bag molding was performed with the prepreg surface treated with a textured roll facing down during lamination. In this case, 5 layers were laminated and no pressure molding was performed. The temperature profile was as shown in Figure 7. At this time, for comparison, a laminate was similarly prepared using prepreg without being subjected to the nip treatment of the uneven roll.

As a result, no pinholes were observed on the surface of the molded product with the prepreg using the uneven roll, but with the prepreg that had not been nipped, more than 20 pinholes were observed at the intersections of the fiber bundles in the 100m x 100 wax cloth. The hall! ! ! It was noticed.

<Effects of the Invention> According to the present invention, by using a textured roll, it is possible to produce cloth (y-nareg) which can be formed so that there are no voids in the formed running laminate and the surface of the laminate has a good appearance. becomes possible.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the prepreg of the present invention after lamination (A
) and a schematic diagram (B) of the prepreg of the present invention supported on release paper, FIG. 2 is a schematic cross-sectional diagram of a conventional laminated prepreg, and FIG. ) and its side view (B), and FIG. 4 show a schematic diagram of an apparatus suitable for manufacturing the prepreg of the present invention. 6 is a preheating plate, and 12 is an uneven roll. Fig. 5 shows a plan view (Fig. 5-A-a and Fig. 5-B-a) and a cross-sectional view (Fig. 5-A-b and Fig. 5-B-1)) of the uneven roll. Matches the direction of the roll. FIG. 6 shows a degassing device for prepreg production, FIG. 7 shows a profile of prepreg curing time and temperature and pressure, and FIG. 8 shows a schematic diagram showing a cut surface of the prepreg.

Claims (1)

[Claims] 1. Textile-reinforced thermosetting resin prepreg having continuous recesses on at least one surface; 2. Forming continuous recesses on the surface of the textile-reinforced thermosetting resin prepreg using a roll having uneven parts. The method for producing a prepreg according to claim 1, characterized in that