JPH02300238A - Impregnation with resin - Google Patents

Abstract

PURPOSE:To increase the rate of impregnation of a fiber layer with a resin and to improve the rate of production of a fiber-reinforced plastic by pressing a resin into a sheet by pressing or clamping with an endless belt having a rugged pattern. CONSTITUTION:A laminate prepared by laying a sheet 2 comprising a reinforcing fiber on a resin film 1 applied to a release paper and further applying a release film 3 to the surface is heated on the surface of a heating drum 4, and when the resin becomes flowable, the resin is infiltrated into the fiber layer of the sheet 2 with an endless belt. As the endless belt, a belt (tube belt) having a sealed space to or from which a fluid can enter or leave in its inside and being capable of giving a pressure to the surface when a fluid enters the endless belt is used. When this tubeless belt is used, the belt is provided with a rotary body having a strong central shaft in position 6-1 as a support and a fluid is introduced into the inside of the tube belt to exert a pressure on the sheet surface by the cooperation of 6-1.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to the use of a novel resin in the production of fiber-reinforced plastics, particularly in the production of flat materials consisting of sheet-like reinforcing fibers and matrix resin. Regarding impregnation method.

<Prior art> One form of fiber reinforced plastic (hereinafter abbreviated as FRP), or a form of medium-thin material for obtaining FRP, is a structure in which a 5y-) shaped material of reinforcing fiber is impregnated with resin. be.

The above-mentioned intermediate material is generally known as Gripreg, and the present invention relates to a method for impregnating it with resin in the production of this prepreg.

Impregnation of resin in this field, regardless of whether the resin is thermosetting or thermoplastic, is the common element of impregnating the resin into the fiber layer by fluidizing the resin by means such as a solvent or heating. For this reason, a typical resin impregnation method that is currently widely used is a hot melt method in which the resin is fluidized by heating.

Specifically, as shown in FIG. 7, a sheet-like material 19 made of one reinforcing fiber is laminated on a resin film 18 in which resin is uniformly coated on a release paper 17, and a heating roll 20 and a press roll 21 are used to stack the sheet-like material 19 into the sheet-like material. The aim is to obtain a prepreg 22 impregnated with resin, and prepreg manufacturing equipment using such an impregnation method has been announced by, for example, California Graphite Machine Enc (Canada) or Calani^G (Switzerland). ing.

These impregnation methods are called breath roll impregnation methods, but the basic problem with this impregnation method is that when trying to improve productivity, that is, to increase the speed of sheet materials, the resin is squeezed out by the press roll. It's about doing. That is, in FIG. 7, the resin fluidized by the heating roll 20 is compressed by the press roll 21 to form the fibers of the sheet material 19! ! Rather than impregnating the layer, the front of the roll (roll 20.
This causes a phenomenon in which the liquid is squeezed out (to the left of the nip point of No. 21).

This phenomenon increases as the diameter of the fibers constituting the sheet material 19 to be impregnated becomes smaller, the direction of the fibers is aligned with the direction of the sheet material, and the thicker the fiber layer becomes. is more pronounced as the resin viscosity increases.

For this reason, the conventional roll impregnation method has been based on reducing the viscosity as much as possible and using a press roll to gradually impregnate the *m layer with the resin. Therefore, the production rate of prepreg is determined by the rate of impregnation of the resin into the fibers mPm of the sheet material, and the conventional roll impregnation method has a problem.

Furthermore, in the conventional roll impregnation method, it is necessary to maintain a low viscosity state for a long time, and in particular, when manufacturing prepreg with a thermosetting resin as a matrix, it is necessary to pay attention to the progress of the curing reaction, and the resin composition must be carefully controlled. This was one of the limiting factors.

Previously, the present inventors proposed a resin impregnation method λ using an uneven press roll as an improved method of the conventional roll impregnation method (@Condylar 63-' (No. 55588)).

However, if the resin has a high viscosity, the prepreg surface is thick, or if you want to increase the production speed compared to K, the method using a concave and convex press roll requires a significant increase in the pressure when applying roll pressure. It was discovered that the production speed had to be lowered. As a result, in the case of a thermosetting resin, a curing reaction of the resin occurs due to heat.

Furthermore, when the press pressure is high and the surface of the prepreg has irregularities, it becomes difficult to apply uniform pressure to the entire prepreg, that is, to impregnate the prepreg.

When a fluid impregnates into a porous material, the rate of penetration is proportional to the pressure applied to the fluid, and the distance of impregnation is proportional to the time the pressure is applied. Therefore, in order to satisfactorily impregnate K into the sheet material, the pressure applied to the resin and the time period during which the pressure is applied may be adjusted. In view of these considerations, the inventors achieved sufficient impregnation of resin into the fibers by increasing the pressurization time, and increased the production speed by increasing the distance between the pressurizing parts. We conducted extensive research on a method for achieving good impregnation by uniformly applying pressure.

<Problems to be Solved by the Invention> The present invention solves the basic drawbacks of the conventional roll impregnation technology, namely, the impregnation rate of resin into the fiber M layer is low, and when trying to increase the production rate, it is difficult to squeeze out the resin. The purpose is to solve various problems caused by the inability to obtain high production rates and long-term heating.

Means for Solving the Problems> That is, the gist of the present invention is to press and hold the resin into the sheet-like material by pressing or clamping it with an endless belt having an uneven pattern when stacking the sheet-like material on top of the resin layer and impregnating it with resin under pressure. The purpose is to press fit the resin inside and impregnate it with resin.

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

FIG. 1 is a schematic diagram showing a resin impregnation method using an endless belt having a specific uneven pattern in the method of the present invention, that is, an impregnation method using an endless belt as a pressurizing section (hereinafter abbreviated as press belt impregnation method). be.

A sheet-like material 2 made of reinforcing fibers is laminated on a resin film 1 coated on a release paper, and the layered product is further covered with a release film 3 on top of the resin film 1. The laminate is heated on the surface of a heating drum 4 to fluidize the resin. Endless belt 5-
1, the fiber layer of the sheet-like material 2 is impregnated with resin.

Here, a belt (hereinafter abbreviated as tube belt) was used as an endless belt, which has a closed space inside which fluid can be taken in and taken out, and whose surface can be pressurized by injecting fluid into the endless belt. When using this tube belt, the pressure applied to the top of the seat must be generated.
The belt was attached to the position of 6-1 using a rotating body with a strong central axis as a support base, and by entering the fluid into the tube belt KE, pressure was generated on the seat surface by interaction with 6-1. .

This tube belt was used as an example because it can effectively apply uniform pressure to the entire body, but other pressurizing methods may also be used. Figure 2 shows an example of a tube belt. FIG. 2-A is an overall view in which a specific pattern with unevenness is formed on the surface of the blade 8.

9 is a fluid inlet, and 10 is a shaft that supports the tube belt main body via a bearing in order to rotate the tube belt. Although air was used as the fluid in this study, other gases or liquids may also be used. FIG. 2-B shows an example of a concavo-convex pattern. FIG. 2-0 is a cross-sectional view of the tube belt. Since the belt receives heat of 100°C to 140°C, ordinary rubber is not suitable.
M5 was constructed by laminating 3.

This uneven belt can be used in combination with a plurality of 5-1, 5-2, etc., and can also be used in combination with an uneven roll, a flat belt, or a flat roll.

The uneven pattern used in the present invention will be explained. The present inventors believe that the key to improving the productivity of prepreg lies in increasing the impregnation rate in the thickness direction of the fiber layer. We investigated the uneven pattern. As a result, it has been found that the most preferable uneven pattern is a pattern having a region of protrusions surrounded by straight lines, curved lines, or both. Although the uneven patterns are illustrated in FIGS. 2-B, 59, and 4, the patterns of the present invention are not limited to these examples.

FIG. 2-B is a typical plan view (FIG. 2-B-a) of a concavo-convex pattern having a convex region surrounded by straight lines, and FIG.
Cross-sectional view of A-A' cross section at B-aK (Figure 2-s-b
). Further, the arrow in the figure coincides with the circumferential direction of an endless belt having unevenness (hereinafter abbreviated as an uneven press belt).

This exemplary pattern has a region of a messenger-shaped convex portion surrounded by straight lines.

The example shown in FIG. 3 is a plan view of a concavo-convex pattern in which a convex region surrounded by curved lines has an elliptical shape.

FIG. 4 is a plan view of another example in which the convex portion is surrounded by straight lines, and is an example in which the convex portion is bent, and all arrows in the figure coincide with the circumferential direction of the uneven press belt.

Figure 5 shows the impregnation mechanism.

In FIG. 5, the resin 1 placed below the y) shaped object 14
5 is pressurized by the convex portion 16-1 of the uneven press belt, so that part of the resin is squeezed out into the fiber layer constituting the sheet-like material, and the remaining resin is squeezed out to the front (right side in the figure). . However, when the convex portion is discontinuous as in the present invention, if the flow is stopped at the concave portion 16-2 by appropriately setting the volume of the concave portion, there is no KEE force. The flow direction of the resin can be changed in the thickness direction. That is, the pressure generated by the excess resin at the convex portion can be converted into pressure for impregnating the fiber layer in the thickness direction. Impregnation is performed by the movement of the resin due to this pressure. When the viscosity is particularly high, it is necessary to increase the time during which this pressure is applied, and the belt method becomes effective.

Therefore, the size of the uneven pattern depends on the belt material and V
-) It should be determined by the pressure a characteristics of the material, etc., but as an example, when rubber is used as the belt material, the maximum length of the convex region in the direction of the belt center is preferably 8 to 10+a+.

In contrast to the concavo-convex pattern having relatively finely divided convex areas as explained above, a pattern in which linear or curved convexities are arranged in parallel, for example, a groove along the rotation axis of the press belt. When using an uneven press belt, the direction of the resin flow as shown in Fig. 5 theoretically occurs, but especially when the sheet-like object is a dough sheet aligned in the positional direction, the fiber orientation is disturbed due to the flow of the resin. This is not a preferred pattern for use as a textured press belt for impregnation, for reasons such as the formation of turbidity and the closure of the flow path for the air that replaces the resin.

However, as will be described later, after the fiber layer is impregnated with a resin using the patterns of the present invention shown in FIGS. 2 to 4, an uneven press belt or an uneven press roll (e.g. This does not restrict the use of a groove roll having a constant pitch in the circumferential direction KFA.

Next, the ratio of the area of the convex portion to the total circumferential area of the uneven press belt (hereinafter referred to as the convex area ratio) is the thickness of the sheet material to be impregnated, and the ratio of the weight of the resin to the weight of the impregnated sheet material. (hereinafter referred to as resin content wt*) is determined by the resin viscosity, but the most important factor is the resin content. - For example, if the sheet-like material is made up of aligned carbon fiber tows, 1
50 f/m'' and the resin to be impregnated is a 10 voice (100°C) epoxy resin, the optimum area ratio of the resin content and the convex portion was determined by experiment, as shown in Figure 6VC. It is necessary to lower the convex area ratio as the area increases.

If the convex area ratio is too large, the resin will be squeezed out by the uneven press belt at the introduction part of the sheet's breath belt, and if it is too small, the pressure that promotes the flow of the resin in the thickness direction of the sheet material will be increased. This does not occur and the effects of the uneven press belt of the present invention as described above cannot be expected. The resin content in the PRP manufacturing method is about 15-60 wt, and the preferable convex area ratio is about 20-90 wt.

In addition, the depth of the recess needs to have a volume that can capture the resin that has penetrated through the sheet material in the thickness direction by the convex part. B-t)
In the case of the triangular shape shown in , the depth may be at least α6 times the depth of the recess. According to experimental results, the optimum pressure for the uneven press belt varies depending on the contact area of the uneven press belt with the sheet, the material of the belt, the viscosity of the resin, the thickness of the fiber layer, the resin content, etc. When the contact length is 250-, the surface pressure is approximately (L1~
20 kg/cm”, preferably 2~I Q kl//
cm” is appropriate.

Next, how to use the uneven belt will be explained.

The textured belt is used as an impregnation method in conjunction with a multi-texture press belt or conventional press rolls as shown in FIG.

For example, in Fig. 1, pressure impregnation is performed on 5-1 and 5-2 using an uneven press belt, 5-3 is a roll with continuous grooves in the circumferential direction, and 5-4 is a smooth roll. A typical example is a combination that provides uniformity and prepreg surface smoothness.

By using such a combination, it is possible to obtain a prepreg with a higher quality with the same thermal history as when using the uneven roll at the 5-1° and 5-2 positions.

Next, the matrix resin used in the present invention will be explained. Since the present invention impregnates a fluid resin into the fiber layer, any resin that shows fluidity when heated may be used, such as unsaturated polyester resin, epoxy V resin,
Thermosetting resins such as phenolic resin, urea resin, melamine resin, diallyl phthalate resin, silicone resin, nylon, polysulfone, polyetherimide, polyether/etherketone, polyvinyl chloride, PBT, PW
Suitable resins include thermoplastic resins such as T% PK.

A sheet-like article to which the present invention is directed will be explained.

The most commonly used form of sheet-like material is the so-called unidirectional notebook, which is a sheet-like form of tow-like material, and the characteristics of the impregnation method of the present invention are particularly exhibited in this unidirectional sheet impregnation.

In other words, in a unidirectional sheet-like material, the flow speed of resin in the thickness direction of the fiber layer and the longitudinal direction of the fibers (longitudinal direction of the sheet) are the most different, and the conventional roll impregnation method has the greatest difficulty in squeezing out the resin. This easily occurs and easily disturbs the fiber orientation. However, according to the impregnation method of the present invention, squeezing and disordered fiber orientation can be solved at the same time.

In addition, since the impregnation method of the present invention performs impregnation while locally restraining the sheet-like material as described above, it is also possible to apply the sheet-like material to a woven fabric or a non-woven fabric that is an aggregate of non-oriented fibers. be.

Such sheet-like materials include carbon fibers, glass fibers, wholly aromatic polyamide fibers, polyester fibers, polyethylene fibers, etc., and the type of material is not particularly limited.

In the case of a sheet made of carbon fiber tow, which has a small fiber diameter and is highly elastic, the difference in resin flow velocity between the thickness direction of the sheet and the orientation direction of the fibers is particularly large. The law is particularly effective.

〔Example〕

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

Example 1 In the impregnation equipment shown in Fig. 1, a resin film 1 with a width of 50 cPR was coated with 6097 m'' of resin on a release paper.
Using resin film,! 12,000 carbon fiber filaments with a diameter of 8μ are arranged in parallel in a 50cfR width as a unidirectional V-toe (240t/?PI), with a thickness as a release film 3. A polypropylene film having a thickness of 20μ was laminated and supplied onto a heating roll 4 whose surface temperature was heated to 130°C.

The uneven press belt and press roll used were as follows.

a. Concave and convex press belt 5-1.5-2 The concave and convex pattern is diamond-shaped as shown in Fig. 2, the short axis of the convex diamond is 3-1, the major axis is 6 m, the concave groove width is α9-1, the depth is αB, and in the circumferential direction. Contact length with the sheet is 250cm (convex area ratio approx. 45mm)
Section). The surface pressure when pressurized is 5 kg.

b. Press roll 5-3 A sinew roll having grooves with a pitch of 1 pitch and a depth α7m in the circumferential direction on a metal roll having an outer diameter of 125mm.

C. Press roll 5-4 Press pressure 30 using a flat roll with an outer diameter of 125 cm
9/Bi3, resin impregnation was carried out at a moving speed of the carbon fiber sheet of 5 ml/minute, but there was no unimpregnated area or disordered orientation of the carbon fibers, and a high quality carbon fiber unidirectional prepreg was obtained.

Comparative Example 1 Impregnation was attempted under the same conditions as in Example 1, except that the uneven press belt used in Example 1 was replaced with an uneven press roll having the same pattern. At this time, the press pressure of the uneven press roll is 50 kg/cm''.As a result, even with the uneven press roll that can perform impregnation at a normal resin content (30~sswt%), the In the case of the low resin content (20wt4) studied, many unimpregnated areas remained.As a result of reducing the production speed to 1 m/min to improve impregnation, the impregnability improved slightly but was sufficient. Moreover, it involved a curing reaction of the resin due to heat, and it was not possible to obtain a prepreg that could be put to practical use.

Example 2 Same conditions as Example 1, except that the amount of resin was 106f 7m
When the experiment was carried out at a moving speed of 40 m/min, carbon fiber, 1!!/-), there was no unimpregnated portion and a high quality carbon fiber unidirectional prepreg could be obtained.

Comparative Example 2 Impregnation was attempted under the same conditions as in Example 1, except that the uneven press belt used in Example 2 was replaced with an uneven press roll with the same pattern. At this time, impregnation using an uneven press roll was possible, but compared to Example 2, <4OF
F! Impregnation at a high speed of /min was not carried out satisfactorily.

Example 3 The same equipment as in Example 1 was used, except that 200 t/m'' nylon with a melting point of 120°C was used as the matrix resin for the resin film.The resin had a viscosity of about 5000 voids when heated to 140°C. , 1000 times the viscosity of a general purpose thermoset epoxy at that temperature.

At this time, the heating roll surface was set at 150° C., the surface pressure of the uneven press belt was set at 5 m/m/min, and the moving speed of the carbon fiber sheet was set at 12 m/min. As a result, a thermoplastic carbon fiber unidirectional prepreg without any unimpregnated portions could be obtained.

If a thermoplastic film is used as the matrix, impregnation is possible even with a textured press roll by raising the temperature and lowering the speed, but the belt method is not recommended because the heat resistance of the release film or the heat resistance of the roller itself becomes a problem. In comparison, its impregnation is difficult.

<Effects of the Invention> According to the present invention, by using the uneven press belt, impregnation with high viscosity resin, production of low resin content prepreg,
It becomes possible to perform high-speed production of general-purpose prepreg.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing a resin impregnation method using a press belt having a specific uneven pattern in the press belt impregnation method of the present invention, and Figures 2 to 4 are planes illustrating the specific patterns used in the present invention Fig. 5 is a schematic diagram for explaining the impregnation process with the uneven pre-preg of the present invention; Fig. 6 is the relationship between the appropriate convex area and the resin content in the prepreg for good impregnation. FIG. 7 is a schematic diagram for explaining the conventional pressurized impregnation method using rolls. 1: Resin film (book with resin coated on release paper) 2: Sheet-like material 3: Release film 4: Heating roll s-t, 5-2: Endless belt 5-3.5--4 Nibbles roll 6 : Pressure support belt 7: Prepreg (resin-impregnated V-) shaped material) 8: Tube belt body 9; Fluid inlet 10: Tube belt center axis 11 to 13: Tube belt structure (M cloth, aluminum foil,
(Silicone rubber) 14: Sheet-like material 15: Resin 16: Uneven belt 17: Release paper 18 Nibbles roll 19: V-)-like material 20: Heater roll 21 Nibbles roll 22 Niblipreg Applicant: Mitsubishi Rayon Co., Ltd. Figure 1 ,6-/Ki 2 concave 3 (2]4 concave 5 citrus citrus spicy (wtl=)

Claims (1)

[Scope of Claims] 1. When pressing and impregnating a sheet-like material on a resin layer with resin, the resin is press-fitted into the sheet-like material by being crimped or clamped with an endless belt having an uneven pattern. Characteristic resin impregnation method. 2. The impregnation method according to claim 1, wherein the uneven pattern has a convex region surrounded by straight lines, curved lines, or both. 3. The impregnation method according to claim 1, characterized in that an endless belt having a concavo-convex pattern in which the area of the convex regions is 20 to 90% of the surface area is used. 4. The impregnation method according to claim 1, wherein the endless belt has a closed space inside which fluid can be taken in and taken out, and the sheet surface can be pressurized by injecting fluid into the inside. 5. The impregnation method according to claim 1, wherein the sheet-like material is a stretched sheet of tow-like material. 6. Claim 1, wherein the sheet-like material is a woven fabric.
Impregnation method as described. 7. The impregnation method according to claim 1, wherein the sheet-like material is carbon fiber.