JPH01115935A - Prepreg manufacturing method - Google Patents

Abstract

PURPOSE:To rationally obtain a high-quality prepreg at increased production speed and reduced energy loss, by impregnating a resin which lowers the viscosity with heat in a carbon fiber tow or sheet heated by passing electric current. CONSTITUTION:The objective prepreg can be produced by impregnating a resin which lowers the viscosity with heat in a carbon fiber tow or sheet while heating the tow, etc., with electric current (the tow, etc., can be heated up to room temperature-500 deg.C).

Description

Detailed Description of the Invention <Field of Industrial Application> The present invention relates to prepreg (hereinafter referred to as hot-melt carbon fiber prepreg), which is a carbon fiber tow or sheet impregnated with a resin whose viscosity decreases when heated. ).

<Prior art> As a method for producing hot-melt primary fiber prepreg, the resin is heated on a heater plate or heater roll to lower the viscosity of the resin, and then the resin is impregnated with edges or pressed with a flat roller, etc. It is carried out by impregnation. According to these methods, if an attempt is made to increase the production speed, it is accompanied by poor impregnation of the resin into the fibers or foaming in the prepreg.
It is difficult to significantly increase the resin temperature to about double the production rate, and in order to rapidly raise the resin temperature to cope with such a production rate, energy loss will be large, or the curing reaction will be slow in thermosetting resins. There are major problems when considering productivity improvement, such as start-up.

<Problems to be Solved by the Invention> The present invention improves the production speed and reduces energy loss, and even when the production speed is significantly increased, there is no impregnation failure or generation of bubbles in the prepreg, and The present invention relates to an excellent and rational method for obtaining a good prepreg in which the curing reaction is suppressed as much as possible even in thermosetting resins.

<Means for Solving the Problems> The gist of the present invention is to impregnate a tow-like material or sheet-like material made of carbon fibers with a resin that causes a decrease in viscosity when heated. The object is to produce prepreg by promoting resin impregnation by energizing a material and generating heat.

The present invention is a method of self-heating the CF) by passing an electric current through the CF), contrary to the process of heating the resin to reduce its viscosity and then impregnating it with the CF). This softens the resin in and around the CF contact area and impregnates the CF with the resin. By this method, since the CF main body has heat, it becomes compatible with the resin, improving the interfacial adhesion between the fiber and the resin, and making it possible to produce a good prepreg. In addition, since the CF) is directly heated by electricity, heat loss is small, and temperature control can be easily and well controlled, making it possible to handle high production rates.

When passing current to CF), either alternating current or direct current can be used. CF) By applying current to the
It is possible to heat up to about 00°C, and the impregnating property of the resin is controlled by adjusting the temperature appropriately depending on the production rate or resin conditions. In addition, when impregnating with resin,
There is no problem in preheating the resin itself on a heater at the same time as the CF) electrical heating, and it is possible to set conditions that balance with the CF temperature to obtain a good prepreg.

Various methods can be considered to further promote impregnation, including edge impregnation, low μ press, and increasing tension in the direction perpendicular to the resin surface of the fibers, but the methods are not limited. The resins used in the present invention include thermosetting resins such as unsaturated polyester resin, Epoquin resin, phenol resin, urea resin, mefmin resin, diallyl phthalate resin, silicone resin, nylon, polysulfone, PEEK,
Polytheimide, vinyl chloride, PBT, PET, P
The type of thermoplastic resin is not limited as long as it is a thermoplastic resin such as P%PE, and its viscosity decreases so that it can be impregnated into a tow-like material or a tow-like material by heating.

The method of applying the electrodes may be low μ application, conductive film application, etc., but is not particularly limited, and the number of electrodes is also not particularly limited. The first example of how to attach the electrode is
As shown in Fig. 2.

In this case, one electrode is removed after resin impregnation, but current flows even if the carbon fiber is covered with resin, and the ti
functions as

〔Example〕

The present invention will be specifically explained below using examples.

Example 1 12K (12,000 carbon fibers) CF') 5
150 pieces are sent out in parallel within the width of 0 tan and made into a sheet, which is made into a 50 ctn sheet with a resin date of 106 fi/rrL".
A voltage was applied by guiding the material onto the release paper, passing through the low/L' electrode before the CF) came into contact with the resin S/), and then contacting it again immediately after the edge after being integrated with the resin sheet. .

The distance between the electrodes was 2fi, the inner part of the resin sheet was 1.5 m, and the voltage sov and current were 140 A.
, the CF temperature was 120°C.

Note that the supply speed was 5 m/min.

A simplified diagram of the electrode setup is shown in FIG. At this time, the impregnating properties of the fibers and the physical properties of the molded product were as follows.

The molding conditions are prepreg sheet 90'C1 vacuum 1k
g/cwt” for 30 minutes, then pressurized at 130°C for 9
/crd'60 minutes.

Impregnability Good Bending strength without unimpregnated parts 180 kg/+m" Flexural modulus 150 T/2 ILSS 11.5 Y/2 Vf 60% Example 2 Under the same conditions as Example 1, except that resin The impregnation method was changed to press pressure skg/α2 using press flow μ instead of edge impregnation.
It was carried out in The electrodes were installed before the resin sheets were integrated and after they were pressed with a press roll μ.

The feed speed was 5 m/min. A simplified diagram of the electrode setup is shown in the second
Shown in the figure. The distance between the electrodes is 2.57FL, and the voltage is 6
The voltage was 0V and the current was 130A.

At this time, the impregnation of the resin into the fibers and the physical properties of the molded product were as follows.

Impregnability Good Bending strength without unimpregnated area 178 Y/2 Bending modulus 115 T/2 I L S S 11.9 kg/w+”Vf
60Ls Example 5 The conditions were the same as in Example 1, except that the tension generating plate in the figure of Example 10 was heated with a heater, and the resin surface was also heated. At this time, C
F) The voltage, current, and interelectrode distance applied to the
The temperature of the tension generating plate was 90°C. The feeding speed at this time was 10 m/min.

At this time, the impregnating properties of the resin into the fibers and the physical properties of the molded product were as follows.

Impregnability Good Bending strength without unimpregnated area 175kg/m" Flexural modulus 13=OT/vm" ILSS 1 t1kl? /w" Vf 60chi Comparative Example 1 The temperature of the resin surface was increased by heating the tension generating plate under the same conditions as in Example 1, except that the CF) current heating was not performed. At this time, the temperature of the resin surface was increased by heating the tension generating plate. The temperature of the resin was 120°C just before the edge.CF) The resin supply rate was as follows:
It was 57 FL/min.

At this time, the impregnation of the resin into the fibers and the physical properties of the molded product were as follows.

Impregnability: Slightly poor Approximately 4 inches of prepreg surface is not impregnated Bending strength: 170 cm/■2 Flexural modulus: 12.8 T/2 ILSS: 9.5 Yu/2 Vf: 60 cm <Effects of the invention> Method of the present invention By using prepregs, the productivity of prepregs can be significantly improved, and products with good physical properties can also be obtained.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are examples showing the steps of the present invention.
The figure shows how to prepare electrodes using the edge impregnation method, and Figure 2 shows how to prepare the electrodes using the breath roll impregnation method. A...! ff1O-~, B...electrode roll, C...
・Film electrode, 1...carbon fiber, 2...resin sheet, 3...tension generation plate, 4...-2dge plate, 5...
Free roll, 6...Press roll, 7...Support plate, 8...Fi μA feed C'-/L', ? ...Film winding roll, 10...Film

Claims (1)

[Claims] A resin characterized in that when impregnating a tow or sheet made of carbon fiber with a resin whose viscosity decreases when heated, the resin impregnation is promoted by energizing the tow or sheet to generate heat. Prepreg manufacturing method using impregnation method.