JPH02298519A - Method for impregnating cloth with resin - Google Patents

Abstract

PURPOSE:To obtain a cloth-reinforced resin prepreg excellent in appearance at a high speed by superposing a clothlike material on a resin layer, pressurizing the superposed material with rolls of uneven pattern, carrying out impregnation of a resin and opening of fiber bundles and preventing resin from its squeezing out or flowing. CONSTITUTION:For example, a clothlike material 2 (preferably composed of carbon fiber) is laminated onto a resin film 1 applied to release paper and coated with a release film 3. The resultant laminated substance is then pressed with uneven press rolls 5 while being heated with the surface of a heating drum 4 to carry out impregnation of the resin and opening of fiber bundles. Furthermore, uneven patterns of the uneven rolls are preferably such that the narrowest width of protruding parts is within 5 times, preferably within 2 times based on the fiber bundle width of the clothlike material and the area of the protruding parts is preferably 20-90% based on the surface area.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for impregnating resin into textiles, which is suitable for manufacturing textile-reinforced resin prepregs (hereinafter abbreviated as cross prepregs) with excellent productivity and product appearance. It depends.

<Prior art and problems to be solved by the invention> As a form of fiber-reinforced plastic (hereinafter abbreviated as FRP) or an intermediate material for obtaining PEP, a sheet-like material of reinforcing fibers is impregnated with resin. There is a structure.

The above-mentioned intermediate material is generally known as prepreg, and includes threads aligned in one direction, woven material,
There are paper-like materials, but woven materials are particularly popular because of their ease of handling and good appearance.

Impregnation with resin in this field, regardless of whether the resin is thermosetting or thermoplastic, is a common element in which the resin is fluidized by means such as a solvent or heating, and the resin is incorporated into the fiber layer. It is impregnation. In the past, most of the IM manufacturing of cross prepregs used solvents, but in recent years, from the viewpoint of ease of handling, methods have been adopted in which fluidization is performed by heating and resin impregnation is carried out in a solvent-free system. has come to be widely used.

Specifically, as shown in FIG. 8, a woven fabric 9 made of reinforcing fibers is laminated on a resin film 8 in which a resin is evenly applied on a release paper 7, and then pressed with a press roll 11 or a belt-like object on a heating roll 1o. The purpose is to obtain a prepreg 12 in which the fabric is impregnated with resin. Alternatively, the resin may be directly coated on the fabric by a transfer method or the like, and the resin may be impregnated under pressure using a similar method. These impregnation methods are called press impregnation methods, but the problems with these impregnation methods are that when trying to improve productivity, that is, increase the moving speed of the sheet material, the press part squeezes out the resin. This is due to the fact that the effect of improving the mobility of the yarn by adding Ff and VC after resin fluidization cannot be fully utilized.

In the press roll method, the resin fluidized by the heating roll 1D in FIG. A phenomenon occurs in which the liquid is squeezed out (to the left of the nip point No. 11). This is squeezing out the resin.

Generally, when a textile is in its gray state, the threads are converged, so the weave is open (Figure 9). Therefore, if this is made into prepreg using the conventional method, the finished prepreg will still have open eyes.

Originally, after the resin becomes fluid and impregnated into the fabric, the fibers become extremely mobile using the fluidity of the resin.
By utilizing this effect, it is possible to eliminate the opening of the fabric, but in the conventional method, this effect cannot be utilized because the entire press surface restrains the yarn.

<Problems to be Solved by the Invention> The present invention solves the basic drawbacks of the conventional press impregnation technology as described above, namely, the inefficiency of squeezing out the resin by the press and the inefficiency of fiber movement using the resin flow. It is.

Means for Solving the Problems〉 The gist of the present invention is that in a pressure impregnation method in which a woven material is layered on a resin layer and then the woven material is impregnated with the resin, specific unevenness is It is a method of impregnating textiles with resin, using a pattern to simultaneously impregnate resin and uniformly spread fiber bundles.

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

FIG. 1 is a schematic diagram of impregnating a resin using a press roll having a specific uneven pattern (hereinafter abbreviated as an uneven press roll) in the pressure impregnation method of the present invention.

A laminate in which a woven material 2 made of reinforcing fibers is laminated on a resin film 1 coated on a release paper, and a release film 3 is further coated on top of the woven material 2 is heated on the surface of a heating drum 4 to fluidize the resin. At this point, the press roll 5-1 impregnates the fiber layer of the woven fabric 2 with resin. In the prior art, the press roll 5-1 is a so-called flat press roll with a smooth surface, but the present invention is characterized by the use of an uneven press roll.

It is also possible to use a plurality of uneven press rolls 5-1, 5-2, 5-3, etc., or a flat press roll. The uneven press roll, which is a basic requirement of the present invention, will be explained below.

A specific uneven pattern on the surface of the uneven press roll will be explained.

The present inventors investigated a method for effectively moving fibers without squeezing out the resin, and found that it is effective to use a press roll with unevenness within a certain size range. We found this out and conducted a thorough study.

The size of the uneven pattern is determined by drawing a perpendicular line from a point on the line that forms the surface to that line or the tangent at that point if the surface where the protrusions act on the prepreg is a flat surface. , consider the distance at the trench where it intersects with another line on the same plane,
If it is a curved surface, consider the same distance as in the case of a flat surface using the secondary plane consisting of the largest ridge in the part that is in contact with the prepreg as a reference, and treat these as the narrowest part of the convex part.

As a result, it was found that a preferable pattern of protrusions and recesses may be 5 times or less the width of the fiber bundle formed by the narrowest part in the convex part, and the shape of the pattern is not particularly limited.

Examples of uneven patterns are shown in FIG. 2 and below, but the patterns of the present invention are not limited to these.

FIG. 2 is a plan view and a cross-sectional view taken along the line AA' of a typical uneven pattern having a region of convex portions surrounded by straight lines. Moreover, the arrow in the figure corresponds to the circumferential direction of the uneven press roll. This pattern has a diamond-shaped convex region surrounded by straight lines.

j FIG. 3 is a plan view of a concavo-convex pattern in which a convex region surrounded by a curved line has an elliptical shape.

FIG. 4 is a plan view of a pattern having continuous grooves along the circumferential direction of the roll.

Japanese Patent Publication No. 57-195619 (Special Publication No. 59-10295)
No.) Publication proposes a prepreg sheet manufacturing method in which air bubbles are removed when a random mat-like material is impregnated with resin using a streaked roll having continuous grooves in the circumferential direction, but the dimensional effect of the uneven roll is There is no mention of &m. In the present invention, the concavo-convex pattern is regulated by the width of the narrowest part of the convex part of the concave-convex press roll, as illustrated in FIGS. The purpose of this patent is to promote the impregnation of the resin into the fabric and to effectively utilize the mobility of the constituent fibers, which is different from the purpose of the publication.

The reason for this phenomenon will be explained below.

The resin placed under the fabric is pressurized by the convex parts of the uneven press roll, and a portion of the resin is transferred into the fiber layer that makes up the fabric.
The excess resin flows to the unpressurized area, but at this time, the upper release film stops the flow, and pressure is generated in the system in the opposite direction. At this time, in the case of a sheet-like prepreg with a unidirectional arrangement, the resin flows out along the fiber direction, but in a woven fabric, the fibers have a crossed shape, so the amount of resin flowing out is small. , it is possible to obtain a good impregnated state with resin movement. Furthermore, since the movement of this resin causes the fibers themselves to move smoothly, the fibers are spread evenly throughout, eliminating the openings seen in the greige state, resulting in a fully woven appearance. Loss prepreg can be obtained.

Therefore, the size of the concavo-convex pattern needs to be within a range that allows the movement of the resin and the fibers to occur easily. In other words, the width of the narrowest part of the convex part of the press part should be within a range that does not interfere with the movement of the resin and fibers, and this should be within 5 times the width of the fiber bundles constituting the fabric according to the results shown in Figure 5. preferably within 2 times,
Furthermore, the uneven shape is preferably discontinuous. However, regarding the shape, continuous patterns are not restricted. A pattern press surface outside this range is too large and strongly restricts the fiber bundle, and also causes squeezing out of the resin, which is not preferable for impregnation and uniform fiber distribution.

The ratio of the area of the convex portion to the total circumferential area of the uneven press roll (hereinafter referred to as the convex area ratio) is determined by the thickness of the fabric to be impregnated, and the ratio of the resin volume to the volume of the impregnated fabric (hereinafter referred to as the resin content ratio). (abbreviated as ), resin viscosity, etc., but the most important factor is resin content. - As an example, if the fabric weight is 150 t/m" and the resin to be impregnated is 10 ps
(100℃) When the optimum area ratio of the resin content and the convex part is determined by experiment, it is necessary to lower the convex part area ratio as the resin content increases, as shown in Figure 6. .

The uneven press roll of the present invention detailed above has been described as having a specific pattern directly on the roll surface.
Patterned belts with similar patterns can also be used. At this time, there is a feature that the direction of the resin flow can be changed more reliably. The heater rolls in the heating section used together do not necessarily have to be large rolls, but each press roll may have a pair of heater rolls, or even if there are many heater plates in the rolls, the impregnation mechanism will be affected. There is no problem because it is directly related. According to experimental results, the optimum pressure for the uneven press roll varies depending on the material of the uneven press roll, resin viscosity, fiber layer thickness, resin content, etc., but the linear pressure is approximately 0.1 to 40 kg/cr. /I, preferably 2-20
Approximately kg/cm is appropriate.

The resin impregnation effect of the uneven press roll of the present invention has been explained above, and next, the method of using such an uneven press roll will be explained.

In order to obtain impregnation and uniform spreading of fibers using a textured press roll, it is effective to pass this press roll through many stages, but as shown in Figure 7, it is not effective when the number of stages exceeds a certain level. It is becoming rare to see a significant increase in In addition, since this pressing is performed under heated conditions, prolonged heating is undesirable for thermosetting resins as it may cause denaturation. From this, there is an optimum value for the number of press stages. Although the value varies depending on the shape of the pattern, resin viscosity, etc., for example, when carbon fiber fabric is impregnated with a thermosetting epoxy resin, about 5 to 7 stages is appropriate. Furthermore, Figure 52
The results shown in FIG. 7 were obtained by measuring the degree of opening of the cross prepreg by measuring the amount of transmitted light immediately after creating the cross prepreg, and converting the amount of light into a voltage value to quantify it. However, since this value varies depending on the configuration method of the photoelectric conversion circuit and the light source used, it is shown as an illustrative comparison.

About the matrix resin used in the impregnation method of the present invention
I will explain. The present invention impregnates the fiber layer with a fluid resin and spreads the fibers uniformly, so the resin is not particularly limited. Resins that show fluidity when heated, such as unsaturated polyester resin, epoxy resin, etc. Thermosetting resins such as resins, phenolic resins, urea resins, melamine resins, diallyl phthalate resins, silicone resins, nylon, polysulfones, polyetherimides, polyether/etherketones, polyvinyl chloride, polybutyl terephthalate, polymers, etc. The woven fabrics include carbon fibers, glass fibers, fully aromatic polyamide fibers, polyester fibers, and polyethylene fibers. The present invention is particularly effective for smooth carbon fiber fabrics that have high elasticity and thus have good impregnation and fiber layering properties.

〔Example〕

The present invention will be specifically explained below with reference to Examples.

Example 1 A plain weave cloth with a fabric weight of 20097 m2 was obtained by using untwisted 3-strand yarn obtained by bundling carbon fibers with a diameter of 8 μm as warp and weft yarns. At this time, the fiber bundle width was about 2 m. This cloth was layered with an epoxy resin film having a basis weight of 200 f/m 2 and subjected to pattern press treatment.

Impregnation was carried out as follows.

The above-mentioned cloth and resin film were overlapped and introduced onto a rotating drum heated to 120°C.

After the position where the resin temperature rose to 100° C., three uneven rolls each having a diameter of 100 mm and a center-to-axis distance of 300 degrees were attached, and pressing was performed using these rolls.

At this time, the press roll convex pattern is elliptical and the depth of the four parts is 1
Fitted, convex area ratio approximately 60, rubber hardness 80 degrees, outer diameter 125
A silicone rubber roll of mm was used. The short axis/long axis ratio of the pattern convex part is 1/2, and the short axis length and pitch between short axes are 5.
The impregnating properties and the spreadability of the fibers were observed by varying the steps.

At this time, press pressure is 4! 9/□□□, the prepreg production speed is 5 m 7 minutes for impregnation. The results are shown in Table 1.

Regarding the impregnation properties in Table 1, as the short axis length increases, the resin squeezes out, and regarding the spreadability of the fibers, as the convex width increases, the fibers no longer move. fl
The situation remained almost unchanged.

Example 2 An experiment was conducted under the same manufacturing conditions as in Example 1, but with different numbers of press rolls. At this time, the shape of the convex portion was the same as that of the experimental flat 2 in Example 1. However, the prepreg production speed at this time was 1.5 cm/7 minutes.

Table 3 <Effects of the Invention> By using an uneven press roll, there is no squeezing out of the resin during impregnation, and it is possible to produce a fabric prepreg with high fiber homogeneity at high speed.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the press roll impregnation method of the present invention in which a press roll having a specific uneven pattern is used to impregnate a fabric with resin, and Figures 2 to 4 illustrate the specific patterns used in the present invention. Figure 5 shows the relationship between the pattern size and impregnability, Figure 6 shows the relationship between the appropriate convex area and resin content in the prepreg for good impregnation, and Figure 7 shows the pattern. Graphs showing the relationship between the number of rolls and impregnation properties, and FIG. 8 is a reference diagram for explaining the conventional roll press impregnation method. 1: Resin film (resin coated on release paper) 2: Textile material 3 Nidotsubu film 4: 110-
Le 5 Nibbles roll 6: Prepreg (resin-impregnated woven material) Patent applicant Mitsubishi Rayon Co., Ltd. Otsuki Brain Containing Special ('/,) Figure 7 Do q 6 δ 10 /2 (Thu)
”y-J 51 reasons / 1 in stock 1 out +
(SP) September 11, 1999 Commissioner of the Japan Patent Office Yoshi 1) Tsuyoshi Moon 1 Indication of case Patent application No. 1-120070 2 Name of invention Method for impregnation of resin into textiles S Amendment case and Related: Patent applicant No. 6-19 Kyobashi 2-chome, Chuo-ku, Tokyo August 29, 1999 (shipment date) 5. Subject of amendment 4. Brief description of the drawings 6. The description of contents of the sleeve has been amended as follows: do. (Page 1117, line 16, ``Reference diagram'' is corrected to ``Schematic diagram, top view of the weave in the state of space between the 9th digit in Figure 9'').

Claims (1)

[Claims] 1. In a pressure impregnation method in which a woven material is layered on a resin layer and then the resin is impregnated into the woven material, a specific uneven pattern is used to impregnate the resin and form the fiber bundle. Method 2 of impregnating a woven fabric with a resin characterized by simultaneously performing homogeneous fiber opening, an uneven pattern in which the width of the narrowest part of the convex part of the uneven pattern does not exceed 5 times the width of the fiber bundles constituting the woven material The impregnation method 3 according to claim 1, characterized in that a press roll having a pattern is used, and the area of the convex region is 20 to 90% of the surface area of the press roll.
The impregnation method according to claim 1, characterized in that a press roll having a concavo-convex pattern of % is used.The impregnation method according to claim 1, characterized in that the woven material is made of carbon fiber