JPS59135121A - Mold release paper for fabricating prepreg - Google Patents

Abstract

PURPOSE:To provide the titled mold release paper generating no transfer of resin to the back surface of the titled paper when the mold release paper is wound up and subsequently unwound, obtained by coating the front and back surfaces of paper with silicone resins so as to bring about specific difference in mold release characteristics. CONSTITUTION:For example, the front and back surfaces of paper are coated with two kinds of silicone resins different in mold releasing characteristics and the mold release characteristics of the back surface are brought to 3 times or more, pref., 5 times or more as compared with that of the front surface to obtain objective mold release paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to resin-impregnated unidirectionally aligned fiber-reinforced prepregs used to make fiber-reinforced plastics.

Unidirectionally aligned fiber-reinforced prepreg is used for sports and leisure goods such as golf shafts, fishing rods, badminton shafts, and tennis racket frames, as well as for industrial use such as leaf springs for vehicles, driving shafts for automobiles, leaf springs, and other ply plates. Silipreg, which is becoming widely used as a material for molding, must maintain its shape well in order to impart excellent properties to molded products made from it. In particular, turbulence that occurs during storage and transportation of fiber-reinforced prepregs that are aligned in one direction not only reduces the moldability of the prepreg but also makes it impossible to impart the desired properties to the molded product, so it must be avoided. It is something that must be prevented.

The unidirectionally aligned reinforced silicone preg that has been developed so far is convenient for storage, transportation, and cutting during molding.
The release paper is pasted and rolled up, and the release paper can withstand the tension when Silipreg is rolled up, and also has a suitable amount of rigidity, and is easy to handle when cutting. Manufactured products have been used. The requirements for the paper quality are to be able to withstand the tension when winding up the prepreg, to have a small dimensional difference between when dry and when absorbing moisture, or to have a rigidity suitable for handling the prepreg, and when cutting the prepreg. There are many things to choose from, such as optimizing the thickness of the paper for ease of tearing, solvent resistance, permeation resistance, and the need for heat resistance as it is subjected to heat treatment of 130°C or higher depending on the Silipreg manufacturing process. requires a high degree of knowledge and experience. In addition to these various performances, in order to supplement the performance of release paper, it is necessary to optimize the release properties of the adhesive surface of the prepreg.

Conventionally, as release paper for unidirectional alignment reinforced prepreg,
Previously, one or both sides of the paper was subjected to a release treatment called polythene coat, and Puri 7' and L/G were laminated to this coated surface, but this polyethylene was removed during the heating process during prepreg manufacturing. There were problems in that Senkoat melted and shattered, and that the release layer and Silipreg were difficult to peel off when the prepreg was used. Furthermore, although silicone coating was applied to the polythene coated surface on one or both sides of the paper to control the mold releasability, there were two cases where the releasability of the adhesive surface of the prepreg was not suitable. It easily peels off from the release paper, and it is difficult to handle because it peels off when rewinding or cutting the flexible preg.

Furthermore, these also had the problem that the polythene coat layer melted during the heating process during prepreg production.

Therefore, instead of forming a release layer using polythene coating, we developed a release paper that coated both sides of paper with silicone, or coated both sides of paper with heat-resistant metal foil and then coated with silicone. The problem of heat resistance was resolved. However, it has been found that the degree of releasability on both sides is a major requirement for release paper for Silipreg.

The general method for producing unidirectional fiber-reinforced pre-regs is to arrange a large number of fiber bundles in one direction, impregnate them with a matrix resin, and roll them up, but the key lies in the method of impregnating the matrix resin.

Impregnation with matrix resin: 1) A method of applying matrix resin dissolved in a solvent to release paper, drying to remove the solvent, and impregnating the aligned fiber bundle with the same, 2) Applying the melted matrix resin to release paper. 3) A method in which a matrix resin dissolved in a solvent is directly adhered to and impregnated into a fiber bundle, placed on a release paper, and dried to remove the solvent. In these methods, if the release characteristics of both sides of the release paper are not appropriate, when the release paper with the matrix resin film attached or the Silipreg placed on the release paper is rolled up once and then rewound, the resin may be transferred to the back side of the release paper. However, it has been found that it is extremely important to differentiate the release properties of both sides of the release paper.

An object of the present invention is to solve this problem and provide a release paper for unidirectionally aligned reinforcing fiber printing legs. That is, the gist of the present invention is a double-sided release paper in which a release layer made of silicone resin is provided on the front and back sides of the paper, and the release property on the back side is three times or more as much as the release property on the front side. Release paper for Silipreg.

Hereinafter, reinforcing fibers for preparing prepregs used in carrying out the present invention include inorganic fibers including carbon fibers, graphite fibers, glass fibers, boron fibers, metal fibers, etc.
Examples include organic fibers such as polyamide fibers and aromatic polyamide fibers. Further, as the matrix resin to be impregnated into the reinforcing fibers aligned in one direction, various materials such as thermosetting or thermoplastic resins can be used, and specific examples thereof include epoxy resin, unsaturated polyester resin, allyl resin, Examples include phenol resin and polyamide resin.

These Silipregs have a fiber content of 30~8゜wt%.
, especially 50 to 70 wt%, and the thickness is 0.05
It is best to set it in the range of ~05 wins. As the thickness of Silipreg increases, the amount of resin coated on the release paper increases, and the resin tends to be transferred to the back side of the release paper, but when the release paper of the present invention is used, such inconvenience does not occur. .

As for the release paper used in the present invention, if the release property of the surface coated with matrix resin or the surface to which resin-impregnated aligned fiber bundles are laminated is 1, the release property of the release surface of the release paper is 3. It is necessary to have a releasability that is easy to peel off, and this value is preferably 5 times or more. It is preferable that the measure of the releasability of the front and back sides of the release paper be expressed by the peel resistance value of the matrix resin itself for Purisoleg used or of the matrix resin-impregnated Purisoleg, but since it is difficult to measure it, in the present invention. This was determined by measuring the peel resistance between the standard adhesive tape and the release surface of release paper. In other words, place three samples of about 180 x 25 mm in the release paper, and then apply standard adhesive tape (length 150 x 19 mm) in the horizontal direction of the paper, gently to prevent air bubbles from entering the treated surface. Crimp. Immediately 3
A static load of 5 g/cm" was applied to the product, and the product was placed in a hot air circulation dryer at 70°C and left for 4 hours. Under the load, it was placed in a measurement chamber (20°C, 65% RH) for mold releasability measurement for 30 minutes. Leave to cool.Use a universal tensile testing machine and apply an appropriate splint.
Measure the 180 degree peel resistance at a speed of 00 + mn/min. Take the measured values at three points (average value, maximum value) and the average value.

According to this measurement method, the releasability of the matrix resin itself or the surface to which the resin-impregnated prepreg is attached and the peel resistance value of the back side are 1/3 or less of the value of the front side. In this case, the desired purpose is achieved because the transfer of resin to the back side of the release paper does not occur when the matrix resin-coated release paper or Silipreg with the release paper bonded to it is rolled up or unwound. It is best to make a difference in mold releasability depending on the type of silicone resin applied to the paper.

The present invention will be explained in more detail by showing an example of producing Grisireg using the release paper of the present invention.

Example: By coating both sides of a paper with a width of 550 mm, a flat surface of 11997 m2, and a thickness of 0125 mm, two types of silicone resins with different release properties were used to achieve a peel resistance value of 4209/1 on the surface.
A release paper of the present invention was prepared using 9111111 and had a resistance value of 55g/19m+n on the back side of about 8.

(a) Using a nip coater, coat the surface of the release paper with a MEK solution containing 85q6 epoxy resin composition and having a viscosity of 20.0OOcpa (25°C);
The resin film was rolled up through a dryer.

While unwinding this again, it was combined with the carbon fiber bundle aligned in one direction, impregnated with resin while rolling with a heated roller, and the Grishireg was rolled up.

When unwinding this resin film and unwinding Grishireg, there was no transfer of resin to the back side of the release paper or sticking of the prepreg, resulting in a product that was easy to handle.

(b) An epoxy resin composition having a melt viscosity of 15,000 cps (70° C.) was coated on the surface of the release paper using a calendar coater and then rolled up. While unrolling this again, it was combined with a carbon fiber bundle aligned in one direction, impregnated with resin while being nipped with a heating roller, and the Silipreg was rolled up.

Both during unwinding of this resin film and unwinding of Silipreg, there was no transfer of the resin to the back surface of the release paper and no sticking of the prepreg.

(c) Carbon fibers aligned in one direction are passed through a MEK solution containing 60 epoxy resin compositions, impregnated with resin, placed on the release paper, and placed in a dryer at approximately 100°C. was passed through and rolled up as prepreg. Even when this prepreg was unrolled again, there was no transfer of the resin to the back side of the release paper and no sticking of the glycereg.

On the other hand, if the ratio of the resistance values on the peeled front and back sides is about 1:2,
(a), (b) and (
When a Presoleg resin film coated product was produced in the same manner as in c), the resin was transferred and Silipreg was stuck to the back side of the release paper, resulting in an inconvenient resin film or prepreg.

Patent applicant: Mitsubishi Rayon Co., Ltd.

Claims (1)

[Claims] A release paper for prepregs that is double-sided release paper with a release layer made of silicone resin on the front and back sides of the paper, and in which the release property on the back side is three times or more higher than that on the front side.