JPS61287936A - Unidirectional prepreg and its production - Google Patents

Abstract

PURPOSE:To produce the titled uniform prepreg at a good rate of production, by impregnating reinforcing fibers drawn unidirectionally and parallelly in sheet form with a B-stage thermosetting resin containing a thermoplastic low- melting polymer. CONSTITUTION:Two release papers 4 and 5 coated with a B-stage thermosetting resin are laid upon the respective upper and lower surfaces of a prepreg base 3 in which warps consist of thermoplastic low-melting polymer yarns (e.g., nylon 6/nylon 12 copolymer) 1 and wefts consist of a number of reinforcing fibers 2 drawn unidirectionally and parallelly with each other in sheet form, and the assemblage is passed between a pair of impregnation rolls 6 heated to 120-170 deg.C and pressed at a pressure of 3-8kg/cm<2> to allow melting of polymer yarns 1 and promotion of spread of fibers 2 and at the same time to allow transfer and infiltration of the resin in the release papers 4 and 5 into material 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a unidirectional prepreg used for molding fiber-reinforced plastics and a method for manufacturing the same.

Conventional technology Unidirectional prepreg (UD prepreg) is made by impregnating B-stage thermosetting resin into reinforcing fibers that are aligned parallel to each other in one direction in a sheet shape, and is a fiber-reinforced plastic (FRP). It is used as a molding material.

Such UD prepregs are generally manufactured by unwinding reinforcing fibers from a number of packages, aligning them parallel to each other in a sheet shape, and then impregnating them with a B-stage thermosetting resin. According to this method, a tJD prepreg in which reinforcing fibers are arranged in the longitudinal direction can be obtained. There is also a method described in Japanese Patent Application Laid-open No. 114046/1983. In this method, first a UD prepreg in which reinforcing fibers are arranged in the longitudinal direction is made by the method described above, the UD prepreg is cut diagonally with respect to the longitudinal direction, and the cut pieces are placed on a release paper with reinforcing fibers arranged in the longitudinal direction. This is a method in which the paper is rearranged so that it is arranged diagonally with respect to the longitudinal direction of the release paper. According to this method, a UD prepreg in which reinforcing fibers are arranged diagonally with respect to the longitudinal direction can be obtained. However, in all of these methods, prior to resin impregnation, it is necessary to arrange a large number of reinforcing fibers in one direction parallel to each other in a sheet shape, or it is necessary to cut and rearrange the reinforcing fibers. Therefore, productivity is very low. In addition, since there is nothing to restrain the reinforcing fibers that are aligned,
It has the disadvantage that it is difficult to obtain a homogeneous UD prepreg because the arrangement of reinforcing fibers becomes disordered during resin impregnation, cracks occur between reinforcing fibers when rearranging, etc., and gaps are formed at the seams between cut pieces.

Problems to be Solved by Akira The purpose of the present invention is to provide a homogeneous UD prepreg. Another object of the present invention is to provide a method for manufacturing such a UD prepreg with high productivity.

Means for Solving the Sub-Problem In order to achieve the above object, in this invention, reinforcing fibers that are aligned parallel to each other in one direction and in the form of a sheet are impregnated with an 8-stage thermosetting resin. , and the thermosetting resin contains a thermoplastic low melting point polymer. In addition, in this invention, as a method for producing such a unidirectional prepreg, a prepreg material made of a large number of reinforcing fibers held in a sheet shape in parallel with each other in one direction by thermoplastic low-melting polymer threads is heated. There is also provided a method for producing a unidirectional prepreg, which comprises melting the low melting point polymer thread and impregnating the reinforcing fiber with a B-stage thermosetting resin.

To explain this invention in more detail, in this invention, first, a prepreg material is prepared in which a large number of reinforcing fibers are held in a sheet shape in parallel with each other in one direction by thermoplastic low-melting polymer threads. This can be done, for example, as follows.

That is, using a loom, the low melting point polymer thread is used as the warp thread, and the reinforcing fiber is used as the weft thread, and both are plainly woven. As a result, a plain woven fabric having the low melting point polymer yarn 1 as the warp and the reinforcing fiber 2 as the weft is obtained as shown in FIG. A prepreg material 3 is obtained in which the fibers are held together by the low melting point polymer threads 1. In this method, by shifting the phase of one of the ears, a prepreg material in which reinforcing fibers are arranged diagonally with respect to the longitudinal direction can be obtained.

In addition, if reinforcing fibers are used as the warp and low melting point polymer threads are used as the weft threads, the reinforcing fibers are arranged parallel to each other in the longitudinal direction in a sheet shape, and the prepreg material is created in which the arrangement is held by the low melting point polymer threads. can get. Note that the low melting point polymer thread only needs to maintain the arrangement of the reinforcing fibers, so it is not limited to a plain texture, but may have other textures such as a satin texture or a twill texture. It is also possible to depend on the knitting structure.

In the above, the thermoplastic low melting point polymer yarn is, for example, a monofilament, multifilament, or slit yarn of nylon, copolymerized nylon, polyester, vinylidene chloride, vinyl chloride, or the like. Among these, it is preferable to use a copolymerized nylon that has good adhesion to a resin forming a so-called matrix of FRP, which will be described later, especially an epoxy resin, and melts at the impregnation temperature of the resin. Such copolymerized nylons include nylon 6 and 12 copolymers, nylon 6 and 66 copolymers, nylon 6.66 and 610 copolymers, nylon 6.12.66 and 610 copolymers. and so on. As mentioned above, the low melting point polymer thread only serves to maintain the arrangement of reinforcing fibers, and does not essentially form the so-called matrix of FRP, so it is better to use as little as possible. good. Therefore,
Although the amount used varies depending on the thickness, arrangement density, retention structure, etc. of the reinforcing fibers, it is preferably about 0.2 to 10% by weight based on the reinforcing fibers. Further, it is preferable that the low melting point polymer thread is as thin as possible so as not to significantly bend the reinforcing fibers. This is because if the reinforcing fibers are bent, stress will be concentrated at the bent portions when FRP is used, and the reinforcing effect will be diminished.

The reinforcing fibers are high-strength, high-strength fibers commonly used in FRP, such as carbon fibers, glass fibers, organic high-modulus fibers (e.g., polyaramid fibers), silicon carbide fibers, alumina fibers, alumina-silica fibers, and boron fibers. Elastic fiber strands (multifilament)
It is. However, two or more types of these reinforcing fibers may be used in combination, for example, by arranging them alternately.

In the present invention, the prepreg material is then heated to melt the low melting point polymer threads, and the reinforcing fibers are impregnated with a B-stage thermosetting resin to obtain a tJD prepreg. This can be done, for example, as follows.

That is, in FIG. 1, the prepreg material 3 has the following properties:
Two sheets of release paper 4.5, each coated with a B-stage thermosetting resin on the - side, are stacked from above and below with the resin-coated side facing the prepreg material 3, and the polymerized body is heated. The material 3 is passed through a pair of impregnated rolls 6 to melt the low-melting point polymer yarn and promote the spreading of the single reinforcing fibers, and at the same time transfer and impregnate the material 3 with the resin of the release paper 4.5 to form a UD prepreg. It is also preferred to preheat the polymer prior to resin impregnation. After impregnation with the resin, the upper release paper 5 is peeled off, but the lower release paper 4 is left as it is and is wound onto the core 7 together with the tJD prepreg.

As shown in FIG. 2, the thus obtained UD prepreg is made by impregnating B-stage thermosetting resin 8 into reinforcing fibers 2 arranged in a sheet shape parallel to each other in the width direction. is. However, as a result of the reinforcing fibers being expanded in the resin impregnation step described above, in this state they are almost separated into individual filaments and do not substantially maintain the form of strands anymore. Therefore, the low melting point polymer thread used for the material remains as polymer 9 in the thermosetting resin. Depending on the type and thickness of the thread used, the temperature conditions during resin impregnation, etc., this polymer may remain in the form of dots, or may remain almost in the form of a thread.

In the above, the release paper is made by coating a blocker such as clay, starch, polyethylene, or polyvinyl alcohol on both sides of paper such as kraft paper, roll paper, or glassine paper with a thickness of about 0.05 to 0.2 mm, and making it rough. A silicone or non-silicone release agent is coated on top of the coating layer.

In addition, the resin applied to such a female pattern is what is called a matrix in the case of FRP, and is a thermosetting resin such as epoxy resin, unsaturated polyester resin, phenol resin, or polyimide resin. .

These resins are B-stage when applied to release paper. However, although the amount applied to the release paper varies depending on the thickness and arrangement density of the reinforcing fibers,
It may be about 50g/m2. Thickness o, ooa~Q,
It is about 3 mm. With such a resin amount, a UD prepreg having a resin content of about 20 to 60% by weight can be obtained. In addition, the release paper coated with resin is t
In order to prevent a difference in the amount of resin between the front and back sides of the JD prepreg, it is preferable to overlap the prepreg materials from both the upper and lower sides as shown in FIG. 1, but it is also possible to overlap only from either side.

Melting of the low melting point polymer yarn and impregnation with resin using an impregnating roll is carried out at about 120 to 170'c. This temperature is the temperature at which the low-melting point polymer thread melts, and the viscosity of the thermosetting resin once becomes low, making it easy to impregnate the reinforcing fibers. In addition, the pressing force is 3 to 8 kg in linear pressure.
/Cm is sufficient. Note that the impregnating rolls may be provided in multiple stages, or a combination of a heat plate and a pressure roll may be used instead of the impregnating rolls.

Example Toshi Co., Ltd.'s carbon fiber "Torayka" T-300 (number of filaments: 6000, fineness: 1B00 denier) and copolymerized nylon yarn "Elder" manufactured by Toshi Co., Ltd. (number of filaments: 10, fineness: 50 denier) , melting point: about 120
'C) was prepared.

Next, using a rapier loom, using the copolymerized nylon yarn as the warp and the carbon fiber as the weft,
Both were flat-woven to obtain a prepreg material with a width of 1 m, which was then wound around a winding core. The density of warp and weft are both 3.
book/cm.

Next, the prepreg material was unwound with a tension of 5 KCI while applying a brake to the winding core, and was supplied to the process shown in FIG.

Next, release paper coated with B-stage prepreg epoxy resin #2500 manufactured by Toshi Co., Ltd. at a rate of 43 g/m2 was superimposed on the above prepreg material from above and below. 1 variable temperature preheated to 125℃
The copolymerized nylon thread was melted and the reinforcing fibers were impregnated with resin by passing through an impregnated roll with a linear pressure of 4 Kq/cm and a circumferential speed of 5 m/min, so that the reinforcing fibers were arranged parallel to each other in the width direction in a sheet shape. UD prepreg was obtained.

In the obtained UD prepreg, there was no disorder in the arrangement of the reinforcing fibers, and the copolymerized nylon existed in dots, but as a whole, in the longitudinal direction of the D prepreg.

Effects of the Invention This invention impregnates a B-stage thermosetting resin into a prepreg material made of a large number of reinforcing fibers held parallel to each other in one direction in a sheet form by thermoplastic low-melting polymer threads. There is no need to line up the reinforcing fibers prior to impregnation, resulting in high productivity. In addition, by selecting the direction in which the reinforcing fibers are arranged, it is possible to
Even UD prepreg in which reinforcing fibers are arranged diagonally with respect to the longitudinal direction can be easily manufactured without going through processes such as cutting and rearranging. Moreover, the alignment of reinforcing fibers is maintained by low melting point polymer threads,
In addition, since the resin impregnation is carried out at the same time as the melting of the low-melting point polymer thread, the arrangement of the reinforcing fibers is not disturbed.Furthermore, the spreading of the reinforcing fibers is promoted by the melting of the low-melting point polymer thread, and the resin is well penetrated between the single threads. The prepared UD prepreg is very homogeneous.

[Brief explanation of the drawing]

Fig. 1 is a schematic process diagram showing how the method of this invention is carried out, Fig. 2 is a schematic perspective view showing a unidirectional prepreg of this invention, and Fig. 3 shows a prepreg material used in this invention. It is a schematic perspective view. 1: Low melting point polymer yarn 2: Reinforcing fiber 3 Niblipreg material 4: Release paper 5: Release paper 6: Impregnated roll 7: Winding core 8: B-stage thermosetting resin 9: Low melting point polymer

Claims (2)

[Claims] (1) B-stage thermosetting resin is impregnated into reinforcing fibers that are aligned parallel to each other in one direction in a sheet form, and the thermosetting resin contains a thermoplastic low melting point polymer. A unidirectional pre-pre rig characterized by: (2) A prepreg material consisting of a large number of reinforcing fibers held parallel to each other in one direction in a sheet shape by thermoplastic low melting point polymer threads is heated, and the low melting point polymer threads are melted and the reinforcing fibers are A method for producing a unidirectional prepreg, characterized by impregnating it with a B-stage thermosetting resin.