JP2005255927A - Thermoplastic resin prepreg and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg which comprises a sheet-like reinforced fiber material and a thermoplastic resin impregnated in it and has an improved variation in the total weight and an excellent uniformity. <P>SOLUTION: The prepreg is obtained by (1) arranging two or more strands of the reinforced fiber material in one direction to form a sheet-like material and adjusting the width of the strand to satisfy the inequality below and the variation in the strand pitch to be below 7% before introducing the sheet-like material into a treatment bath containing the thermoplastic resin, (2) introducing and immersing the sheet-like material in the treatment bath to stick the thermoplastic resin in the material and (3) tentering the sheet-like material taken up from the bath. The inequality is W/0.7≥1000×Y/F, wherein W is a strand width (mm): F is the weight of the sheet-like material (g/m<SP>2</SP>); Y is the weight of the strand per unit length (g/m). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a prepreg having excellent uniformity and comprising a sheet-like reinforcing fiber material and a thermoplastic resin impregnated therein, and a method for producing the same.

  In recent years, reinforcing fiber materials such as carbon fibers, glass fibers, and aramid fibers have been combined with various matrix resins, and the resulting reinforcing fiber composite materials have been widely used in various fields and applications. And in the aerospace field and general industrial fields where high mechanical properties and heat resistance are required, conventionally, thermosetting resins such as unsaturated polyester resin, epoxy resin, and polyimide resin have been used as matrix resins. It has been. However, especially in the aerospace field, these matrix resins have the drawbacks of being brittle and inferior in impact resistance, and therefore, improvement has been demanded. Further, in the case of a thermosetting resin, when this is used as a prepreg, there are problems in the storage management of the prepreg due to the life of the resin, and problems such as a long molding time and low productivity.

On the other hand, in the case of a thermoplastic resin prepreg, the impact resistance when it is made into a composite material is excellent, the storage management of the prepreg is easy, the molding time is short, and the molding cost may be reduced. Conventional methods for producing a thermoplastic resin prepreg include, for example, a method in which a film-like resin is heated and melted to impregnate a reinforcing fiber material (melting impregnation method), and a powdery resin is reinforced by a fluidized bed method or a suspension method. A method of applying and fusing to a fiber material (powder method) and a method of making a resin into a solution and removing the solvent after impregnating the reinforcing fiber material (solution impregnation method) are known. However, the melt impregnation method has a high melt viscosity of the resin, so it is difficult to uniformly impregnate the resin into the inside of the fiber material. In the powder method, it is difficult to adjust the amount of the resin adhered, and the solution impregnation method However, there are problems and drawbacks in that the types of resins and solvents that can be used are limited.

As a prepreg manufacturing method improved from the prior art, a thermoplastic resin powder is dispersed in an organic solvent such as alcohol or a mixed solvent of an organic solvent and water to form a suspension, and a carbon fiber strand or sheet is immersed in the suspension. A method has been proposed in which resin powder is attached to a strand or sheet and then heated to melt the resin so that the thermoplastic resin and the carbon fiber strand or sheet are integrated. According to this method, when a prepreg impregnated with resin relatively uniformly (variation value of impregnated resin amount is 4.2 to 5.0) is obtained, and furthermore, a method of performing energization treatment on the suspension is combined, a variation value is obtained. It is exemplified that 2.8 to 3.8 were also obtained.
4-12894

  However, as a recent material in the field of aerospace, in particular, a prepreg having further excellent uniformity and the like has been demanded, and its manufacturing method needs to be as simple as possible.

  The present invention provides a prepreg that is composed of a sheet-like reinforcing fiber material and a thermoplastic resin impregnated therein and has a small total basis weight (fiber material basis weight + resin basis weight) and excellent uniformity. It is for the purpose.

An object of the present invention is a prepreg comprising a sheet-like reinforcing fiber material and a thermoplastic resin impregnated therein, wherein the prepreg has a total basis weight variation value of 7% or less. Achieved by resin prepreg. Here, impregnation means a state in which the resin adhering to the reinforcing fiber material is once melted and the resin is present as a continuous layer between the fibers or on the fiber surface. The total basis weight means the basis weight of the prepreg, that is, the total basis weight of the fiber material and the basis weight of the resin, and the variation value of the total basis weight of the prepreg is the width direction of the prepreg (relative to the length direction of the sheet-like material). In the width direction).

And when this inventor manufactures this prepreg, it discovered that the total fabric weight of a prepreg could also be improved if the fabric weight spot of the width direction of a sheet-like reinforcing fiber material was reduced. That is, when a prepreg is produced by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction, (1) a plurality of reinforcing fiber materials The strands are aligned in one direction to form a sheet, and before the sheet is introduced into the treatment bath containing the thermoplastic resin, the width of the strand satisfies the following formula and the variation value of the strand pitch is 7 % To be less than
W / 0.7 ≧ 1000 × Y / F
(W: Strand width (mm), F: basis weight of sheet-like material (g / m ² ), Y: weight per unit length of the strand (g / m))
Next, (2) the sheet is introduced and immersed in a treatment bath to attach a thermoplastic resin, and then the sheet is obtained from the treatment bath.

Further, in the case of manufacturing a prepreg by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction, (1) a plurality of reinforcing fiber materials The strands are aligned in one direction to form a sheet, the sheet is introduced and immersed in a treatment bath containing a thermoplastic resin, and the thermoplastic resin is adhered to the sheet, and then (2) the sheet It can also be obtained by a method characterized in that after the product is led out from the treatment bath, the sheet-like product is widened.

Alternatively, a method that combines the adjustment of the dispersion value of the strand width and strand pitch before introduction into the treatment bath and the widening treatment after derivation from the treatment bath as described above is a more preferable method.

According to the present invention, a reinforced fiber material can be impregnated with a thermoplastic resin uniformly and even inside, and a prepreg excellent in uniformity can be obtained with little unevenness in total basis weight. The obtained prepreg can be molded into a reinforced fiber composite material for various uses by using this, and the physical properties such as mechanical properties and heat resistance of the obtained composite material are extremely high because the prepreg has high uniformity. It will be excellent.

The present invention comprises a sheet-like reinforcing fiber material and a thermoplastic resin impregnated therein, and has a small total basis weight, that is, a variation value of 7% or less, preferably 5% or less. Although it is an excellent prepreg, the content of the thermoplastic resin in the prepreg is 10 to 70% by weight, more preferably 20 to 50% by weight.

In the present invention, the sheet-like reinforcing fiber material means a sheet-like material in which strands of fiber material (monofilament aggregates) are aligned in one direction. As the reinforcing fiber material, there are fiber materials made of inorganic fibers, organic fibers, metal fibers, or a mixture thereof. Specifically, examples of the inorganic fiber include carbon fiber, graphite fiber, and glass fiber. Examples of organic fibers include aramid fibers, high density polyethylene fibers, polyamide fibers, and polyester fibers. Preference is given to carbon fibers and aramid fibers.

  The thermoplastic resin used in the present invention is not particularly limited, but a crystalline or amorphous thermoplastic resin having a melting point or glass transition temperature of 150 ° C. or higher is preferable. Specific examples of preferred resins are polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, polyamideimide It is. Two or more of these resins may be used in combination.

The prepreg of the present invention is produced by the following method. That is, in manufacturing a prepreg by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction, (1) Before the sheet material is introduced into the treatment bath containing the thermoplastic resin, the width of the strand satisfies the following formula and the variation value of the strand pitch is 7% or less. Adjust so that
W / 0.7 ≧ 1000 × Y / F
(W: Strand width (mm), F: basis weight of sheet-like material (g / m ² ), Y: weight per unit length of the strand (g / m))
Next, (2) the sheet is introduced and immersed in a treatment bath to attach a thermoplastic resin, and then the sheet is obtained from the treatment bath.

  The present inventor has found that in order to obtain a prepreg having a target specification, the width of the strands to be kept in the manufacturing process and the uniformity of the pitch of the strands are important, and the width of the strands is a reinforcing fiber. It has been found that the above formula should be satisfied in relation to the basis weight F of the material (the basis weight of the sheet-like material) and the weight Y per unit length of the strand. If this relationship is not satisfied, a prepreg excellent in uniformity with a total basis weight variation value of 7% or less cannot be obtained.

  FIG. 1 schematically shows a state in which a plurality of strands of reinforcing fiber material are aligned in one direction. In FIG. 1, reference numeral 1 denotes a strand that is an aggregate of monofilaments. The strand width in the above formula means 2 in FIG. 1, and the strand pitch means the interval 3 between strands. And the dispersion value of a strand pitch means the deviation value with respect to the average value of the value measured arbitrarily in ten places.

In the present invention, the method and means for adjusting the strand width and strand pitch are not particularly limited. For example, a yarn guide adjusting guide such as a comb guide is provided immediately before the strand is introduced into the treatment bath. It is convenient to keep it. By adjusting the width of the guide, the strand width and the strand pitch can be arbitrarily set.

Next, the sheet-like material in which a plurality of strands are aligned in one direction is introduced and immersed in a treatment bath containing a thermoplastic resin, and the thermoplastic resin is adhered thereto. The treatment bath may be a thermoplastic resin solution, suspension, emulsion, or the like, but is preferably a suspension bath of thermoplastic resin powder. In particular, a suspension in which a thermoplastic resin powder is dispersed in one or more organic solvents selected from alcohols, ketones, and halogenated carbons, or a mixed solvent of such an organic solvent and water, which is a dispersion medium. Is preferred. Examples of alcohols include methanol, ethanol, isopropyl alcohol, and methyl cellosolve. Examples of ketones include acetone and methyl ethyl ketone. Examples of halogenated hydrocarbons include methylene chloride and dichloroethane. Of these, ethanol, isopropyl alcohol, acetone or a mixed solvent thereof with water is preferable. Such a dispersion medium also has an effect of appropriately opening the fiber material when the sheet-like reinforcing fiber material is immersed, so that it is effective for the resin powder in the suspension to uniformly adhere to the fiber material.

The resin powder has a particle diameter of 50 μm or less in view of good adhesion to the reinforcing fiber material (a state in which the resin powder is held between fibers or on the fiber surface), which is less than 1 μm from the viewpoint of handling. The average particle size is preferably in the range of 5 to 20 μm.

The concentration of the thermoplastic resin in the suspension ((thermoplastic resin weight / dispersion medium weight + thermoplastic resin weight) × 100) is 1 to 50% by weight, preferably 1 to 30% by weight, more preferably 5 to 15% by weight. %.

The temperature of the suspension when immersing the sheet-like reinforcing fiber material is not particularly limited as long as the dispersion state of the resin is kept good, and varies depending on the type and concentration of the thermoplastic resin and dispersion medium used. Usually, it is 5-50 degreeC, Preferably it is 5-30 degreeC, More preferably, it is 15-30 degreeC. The immersion time depends on the amount of the thermoplastic resin attached, but usually 5 to 180 seconds is sufficient.

Under the conditions described above, 10 to 70% by weight (based on the total amount of the fiber material and the thermoplastic resin) of the thermoplastic resin adheres to the sheet-like reinforcing fiber material. About 20 to 50% by weight is preferable.

Thereafter, the sheet-like material to which the thermoplastic resin is adhered is drawn out (derived) from the treatment bath. Usually, such a sheet is dried at a temperature at which the thermoplastic resin does not decompose or react. Generally, it is dried at 80 to 200 ° C. for 1 to 20 minutes. Next, the dried reinforcing fiber material is heated to such an extent that the resin melts in the heating zone. Heating can be performed by passing between rollers heated to 100 to 400 ° C. or between slits, or passing through an atmosphere at such a temperature. The resin adhered by such treatment is melted.

When the prepreg of the present invention is produced by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction, (1) A plurality of strands are aligned in one direction to form a sheet, the sheet is introduced and immersed in a treatment bath containing a thermoplastic resin, and the thermoplastic resin is adhered to the sheet, and then (2) the It can also be produced by a method in which after the sheet-like material is derived from the treatment bath, the sheet-like material is subjected to a widening treatment.

In the present invention, the method and means of the widening treatment for spreading the sheet-like material are not particularly specified. For example, a blower is installed following the introduction / impregnation step into the treatment bath, and the sheet-like material is compressed with air, etc. The method of spraying is convenient. In the case of blowing compressed air or the like, the pressure, the air volume, and the like are not particularly limited, and conditions for obtaining a desired widening effect can be arbitrarily set within a range that does not adversely damage the sheet-like material. . By this widening treatment, the strands can be prevented from converging, and the fabric weight in the width direction can be stabilized. As a result, the fabric weight of the sheet and the adhesion spots of the impregnated resin are improved. Moreover, the effect that the resin adhering excessively on the surface of a sheet-like material is removed is also acquired.

In the present invention, as described above, a method in which the adjustment of the dispersion value of the strand width and the strand pitch before introduction into the treatment bath and the widening treatment after derivation from the treatment bath are combined is a more preferable method.

In the present invention, in order to further enhance the adhesive force between the sheet-like material made of the reinforcing fiber material and the thermoplastic resin, when a fiber sizing agent, an oil agent, a paste or the like adheres to the strand of the reinforcing fiber material It is desirable to remove these in advance.

An example of the manufacturing method of the present invention will be described with reference to FIG. In FIG. 2, the strand 1 of the reinforcing fiber material taken out from the creel 4 forms a sheet-like material 6 through a yarn path adjusting guide 5, and is introduced into a treatment bath 7 containing a thermoplastic resin. While the sheet 6 passes through the treatment bath 7, the resin is adhered to the sheet 6. Next, the sheet-like material 6 taken out from the processing bath 7 is introduced into a dryer 9 and dried by removing the solvent or the dispersion medium. Next, the sheet-like material 6 is heated to such an extent that the resin is melted in the heating zone 10, and the resin is melted and impregnated between the fiber material surface and the fibers. Next, the sheet-like material 6 is taken up by the take-up roller 12 through the take-up roller 11.

Hereinafter, the present invention will be described with reference to specific examples. In each of the examples and comparative examples, the uniformity of the obtained prepreg was evaluated based on the variation value of the total basis weight. The variation value was expressed as a deviation value (%) from the average value by cutting 10 pieces of a 20 mm × 100 mm square test piece at 10 mm intervals in the width direction of the sheet-like prepreg and measuring the total basis weight.

Polyimide resin (PIXA-M manufactured by Mitsui Chemicals) powder (average particle size 12 μm) was dispersed in acetone to prepare a 7% concentration suspension. Parallel carbon fiber strands (IM6000 manufactured by Toho Tenax Co., Ltd., 24,000 filaments with a single fiber diameter of 5 μm assembled, weight per unit length of strand (Y): 0.8 g / m) in a suspension bath Fifty aligned sheets (weight per unit area (F): 133 g / m ² ) were immersed for 30 to 60 seconds, and the amount of resin adhered was adjusted to 35% by weight. A comb guide (pitch: 3.8 mm, wire diameter: 1.8 mm) is provided as a yarn path adjustment guide adjacent to the introduction portion of the suspension bath, and the strand immediately before being introduced and immersed in the suspension bath is passed through this guide. Thus, the strand width (W) was adjusted to 5.8 mm, and the strand pitch and its variation value were adjusted to 5.0 mm and 6.8%, respectively. (In the formula of W / 0.7 ≧ 1000 × Y / F, W ≧ 4.2).

A blower using compressed air is installed adjacent to the suspension bath outlet, and 5 kg / cm ² of compressed air is applied to the sheet-like material taken out (derived) from the suspension bath and attached to the resin for 1 to 2 seconds. The sheet was widened. Subsequently, the sheet-like material was dried at 150 ° C. for 1 to 2 minutes, and then passed through a heat roller having a surface temperature of 320 to 340 ° C., and the resin was heated and melted to impregnate the carbon fiber material. A reinforced carbon fiber prepreg was obtained. The total weight of the obtained prepreg was 205 g / m ² , and the variation value was 4.2%.

In Example 1, the widening process by the blower is omitted, and the strand immediately before being introduced and immersed in the suspension bath is passed through the comb guide, whereby the strand width (W) is set to 4.3 mm, the strand pitch and the variation value thereof. Were adjusted to 5.1 mm and 6.5%, respectively, and in the same manner as in Example 1, a thermoplastic resin prepreg was obtained. The total weight of the obtained prepreg was 205 g / m ² and the variation value was 6.9%.

In Example 1, the adjustment of the strand by the yarn path adjusting guide was omitted, and the others were the same as in Example 1 to obtain a thermoplastic resin prepreg. In this case, the strand width (W) of the strand introduced and immersed in the suspension bath was 6.1 mm, and the strand pitch and its variation value were 5.3 mm and 15.6%, respectively. The total weight of the obtained prepreg was 203 g / m ² and the variation value was 5.8%.

The experiment of Example 3 was repeated while changing the carbon fiber strands in Example 1 (strand adjustment by the yarn path adjusting guide was omitted). In this case, the strand width (W) of the strand introduced and immersed in the suspension bath was 4.0 mm, and the strand pitch and the variation value thereof were 5.3 mm and 18.5%, respectively. The total weight of the obtained prepreg was 203 g / m ² and the variation value was 6.8%.

[Comparative Example 1]
In Example 1, a thermoplastic resin prepreg was obtained in the same manner as in Example 1 except that the widening process by the blower and the strand adjustment by the yarn path adjusting guide were omitted. In this case, the strand width (W) of the strand introduced and immersed in the suspension bath was 4.1 mm, and the strand pitch and the variation value thereof were 5.5 mm and 18.2%, respectively. The total basis weight of the obtained prepreg was 201 g / m ² , and the variation value was 10.1%, which was inferior in uniformity.

  The prepreg excellent in uniformity of the present invention can be laminated according to the purpose, and heated and pressurized again to be formed into a composite material having a substantially uniform structure. Since the obtained composite material has excellent mechanical properties such as impact resistance and excellent heat resistance, it is widely used in aerospace and general industrial fields.

Schematic showing the state of multiple strands aligned in one direction Schematic which shows an example of the manufacturing process for manufacturing the prepreg of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Strand of reinforcing fiber material 2 Strand width 3 Strand pitch 4 Creel 5 Yarn path adjustment guide 6 Sheet-like material 7 Treatment bath 8 Blower 9 Dryer
10 Heating zone
11 Take-up roller
12 Winding roller

Claims (11)

A thermoplastic resin prepreg comprising a sheet-like reinforcing fiber material and a thermoplastic resin impregnated with the sheet-like reinforcing fiber material, wherein a total basis weight variation value of the prepreg is 7% or less. The thermoplastic resin prepreg according to claim 1, wherein the total basis weight variation value of the prepreg is 5% or less. The thermoplastic resin prepreg according to claim 1 or 2, wherein the content of the thermoplastic resin in the prepreg is 10 to 70% by weight. The thermoplastic resin prepreg according to claim 1, wherein the thermoplastic resin is a crystalline or amorphous thermoplastic resin having a melting point or a glass transition temperature of 150 ° C. or higher. The group in which the thermoplastic resin is polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, polyamideimide The thermoplastic resin prepreg according to claim 1, which is one or more resins selected from In manufacturing a prepreg by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction,
(1) A plurality of strands of reinforcing fiber material are aligned in one direction to form a sheet, and before introducing the sheet into a treatment bath containing a thermoplastic resin, the width of the strand satisfies the following formula: And adjusting the strand pitch variation value to be 7% or less,
W / 0.7 ≧ 1000 × Y / F
(W: strand width (mm), F: basis weight of sheet-like material (g / m ² ), Y: weight per unit length of the strand (g / m))
Next, (2) a method for producing a thermoplastic resin prepreg, wherein the sheet-like material is introduced and immersed in a treatment bath to attach a thermoplastic resin, and then the sheet-like material is led out from the treatment bath. In manufacturing a prepreg by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction,
(1) A plurality of strands of reinforcing fiber material are aligned in one direction to form a sheet, and the sheet is introduced and immersed in a treatment bath containing a thermoplastic resin, and the thermoplastic resin is attached to the sheet. (2) A method for producing a thermoplastic resin prepreg, wherein after the sheet-like material is led out from the treatment bath, the sheet-like material is subjected to a widening treatment. In manufacturing a prepreg by impregnating a thermoplastic resin into a sheet-like material obtained by aligning a plurality of strands of reinforcing fiber material in one direction,
(1) A plurality of strands of reinforcing fiber material are aligned in one direction to form a sheet, and before introducing the sheet into a treatment bath containing a thermoplastic resin, the width of the strand satisfies the following formula: And adjusting the strand pitch variation value to be 7% or less,
W / 0.7 ≧ 1000 × Y / F
(W: Strand width (mm), F: basis weight of sheet-like material (g / m ² ), Y: weight per unit length of the strand (g / m))

Next, (2) introducing and immersing the sheet-like material in the treatment bath to adhere the thermoplastic resin, and then (3) conducting the widening treatment on the sheet-like material after the sheet-like material is led out from the treatment bath. A method for producing a thermoplastic resin prepreg. The treatment bath is a suspension bath in which thermoplastic resin powder is dispersed in one or more organic solvents selected from alcohols, ketones and halogenated carbons or a mixed solvent of such organic solvents and water. The method for producing a thermoplastic resin prepreg according to claim 6, wherein the thermoplastic resin prepreg is provided. The average particle diameter of thermoplastic resin powder is 5-20 micrometers, The manufacturing method of the thermoplastic resin prepreg of Claim 9 characterized by the above-mentioned. The method for producing a thermoplastic resin prepreg according to claim 9, wherein the concentration of the thermoplastic resin in the suspension bath is 1 to 50% by weight.

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