JP2003002990A - Prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg good in resin impregnability of the reinforcing fibers in processing and molding, excellent in tuck, drape and windability without deterioration with time. SOLUTION: This prepreg is obtained by impregnating carbon fibers having 280-800 GPa in tensile modulus with a matrix resin essentially comprising (A) 20-70 wt.% of an epoxy resin 1-70 p in viscosity at 25 deg.C, (B) 15-50 wt.% of a 2nd epoxy resin 80-160 deg.C in softening point and (C) 5-20 wt.% of a thermoplastic resin 5,000-200,000 in weight-average molecular weight soluble in the matrix resin. The prepreg is also obtained by impregnating carbon fibers 280-800 GPa in tensile modulus with a matrix resin meeting the following requirement(s) (a) and/or (b): (a) 500-50,000 Pa in storage modulus (hereafter abbreviated as G') determined by a dynamic viscoelasticity measurement at 0.5 Hz and 50 deg.C and/or (b) the ratio of the G' determined by the dynamic viscoelasticity measurement at 0.5 Hz and 10 deg.C to the G' determined by a dynamic viscoelasticity measurement at 0.5 Hz and 50 deg.C is 1,000-50,000.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a prepreg impregnated with a resin composition. For more details, tack,
High-quality, high-performance prepreg with excellent drape and wrapping property.

[0002]

BACKGROUND OF THE INVENTION Fiber-reinforced composite materials composed of reinforcing fibers and matrix resins are lightweight and have excellent mechanical properties. Therefore, they are used for sports such as golf shafts, fishing rods, and tennis rackets, aerospace applications, and general industries. Widely used for purposes.

Conventionally, various methods have been used for producing fiber-reinforced composite materials, but nowadays, a method using a prepreg which is a sheet-like intermediate base material in which reinforcing fibers are impregnated with a matrix resin is widely used. Has been. In this method, a plurality of prepregs are laminated and then heated, whereby a fiber-reinforced composite material can be obtained as a molded product.

As the matrix resin used in the prepreg, both a thermosetting resin and a thermoplastic resin are used. In most cases, a thermosetting resin is used, among which heat resistance, hardness and dimensional stability are used. Epoxy resins (cured products), which have excellent mechanical and chemical properties such as properties and chemical resistance, are mainly used. Here, the term thermosetting resin or epoxy resin is generally used in two meanings of a prepolymer and a cured product obtained by reacting a composition obtained by mixing a prepolymer with a curing agent and other components. To be As used herein, the term thermosetting resin or epoxy resin refers to
Unless otherwise noted, it is used to mean prepolymer.

When using a prepreg using a thermosetting resin, the tackiness (adhesiveness) between the prepregs and the drapeability (flexibility) between the prepregs are often problems. These properties greatly affect the workability when handling the prepreg.

The tackiness referred to in the present specification is a value detected by a tack test which will be described later, and is a degree of difficulty in peeling between prepregs at a peeling speed which is actually equivalent to peeling from a mandrel. Therefore, not the tackiness of the prepreg, which mainly reflects the wettability, but the peeling strength against slow peeling after sufficient contact is treated as tack.

That is, if the tackiness of the prepreg is too small, the prepregs that have been stacked are immediately peeled off in the prepreg laminating step, which impedes the laminating operation. On the other hand, if the tackiness of the prepreg is too large, for example, if the prepregs are mistakenly piled up, it is difficult to peel them off. Further, if the drape property of the prepreg is poor, the workability in the case of stacking using a mold having a curved surface or a mandrel is significantly reduced.

In recent years, the weight has been reduced particularly in the use of sports equipment such as golf shafts and fishing rods, and there is a demand for a prepreg suitable for a lightweight design. In recent years, prepregs using high-modulus fibers, especially high-modulus carbon fibers as reinforcing fibers have been particularly desired in the market because of their ease of lightweight design. Moreover, the demand for prepregs having a high content of reinforcing fibers is also increasing.

However, when the high elastic modulus carbon fiber is used as the reinforcing fiber, the drape property of the prepreg is lowered. In addition, when the reinforcing fiber content is high, the amount of resin distributed on the surface of the prepreg is small, and thus the tackiness tends to be low. Therefore, the prepreg using the conventional matrix resin has a problem that tackiness, drapeability, or both are insufficient.

Therefore, some methods for improving the resin composition in order to obtain good tackiness or drapeability have been proposed as described below.
Generally, when tackiness is improved, drapeability is sacrificed. A golf shaft and a fishing rod are molded by winding a prepreg around a mandrel having a relatively small diameter. When the force for peeling the prepreg exceeds the adhesive force (tackiness) between the prepregs, the prepreg wound around the mandrel peels off, making the winding operation difficult. The force for peeling the prepreg increases as the drapability decreases. Therefore, even if the tackiness is improved by sacrificing the drape property, the mandrel winding operation itself is not improved so much.

On the other hand, as a method for improving the handleability of the prepreg, a method of controlling the rheological properties of the resin composition by defining the types and blending amounts of the epoxy resin component, the thermoplastic resin and the elastomer has been attempted. There is. Liquid bisphenol A type epoxy resin described in JP-A-63-308026, in which a polyvinyl formal resin described in JP-A-62-169829 is blended and viscosity at 70 ° C. is defined. And a high molecular weight bisphenol A type epoxy resin are used in combination, and the viscosity at 80 ° C. is regulated.
JP-A-9-87359 discloses a method of blending a bisphenol A type epoxy having an epoxy equivalent and a softening point specified in JP-A No. 20 and a nitrile rubber, and defining a viscosity at 40 ° C. and 80 ° C. A method in which the viscosity at 30 ° C. is specified and the slope of the tangent line in a certain viscosity range in the viscosity curve measured by temperature-rising viscosity measurement is specified.
No. 0358, a method of blending an epoxy resin having an oxazolidone skeleton and defining a viscosity at 60 ° C., a heat having a weight average molecular weight of 200,000 to 5,000,000 described in JP-A No. 11-5887. A method in which a plastic resin is blended and the complex viscosity at 50 ° C. and G ′ and the G ′ / complex viscosity ratio are specified, JP-A-11-27.
There is known a method described in Japanese Patent No. 9297, in which a specific amount of a thermoplastic resin and an elastomer are blended and the complex viscosity and energy loss at 30 ° C. are specified.

However, only by defining the viscosity at 40 to 80 ° C., although the process passability during the preparation of the prepreg was secured, it was still impossible to obtain an appropriate tack drape property. In addition, it is difficult to achieve both tack drape and processability when the viscosity curve slope is specified. Regarding the one in which the complex viscosity and the energy loss at 50 ° C. and 30 ° C. are specified, the tack drape property can be secured, but there is a problem that the viscosity is high in the high temperature region and the process application is difficult.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a prepreg which has excellent processability when producing a prepreg, excellent tack, drape, and winding property, and which is less likely to change with time.

[0014]

The prepreg of the present invention comprises:
In order to achieve the above-mentioned object, it has the following composition. That is, it is a prepreg obtained by impregnating a carbon fiber having a tensile elastic modulus of 280 to 800 GPa with a matrix resin containing at least the following constituent elements A to C. A. Epoxy resin having a viscosity of 1 to 70 poises at 25 ° C:
20-70% by weight B.I. Epoxy resin having a softening point of 80 to 160 ° C .: 15 to 5
0 wt% C.I. Thermoplastic resin soluble in a matrix resin having a weight average molecular weight of 5,000 to 200,000: 5 to 20% by weight, and a matrix satisfying the following conditions a and / or b in carbon fiber having a tensile elastic modulus of 280 to 800 GPa. It is a prepreg impregnated with a resin. a. Storage elastic modulus (hereinafter abbreviated as G ′) measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. is 500 to 500.
00 Pa b. The ratio of G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 10 ° C. and G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. is 1000 to 50000.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The prepreg of the present invention comprises carbon fibers and a matrix resin, and as the matrix resin, epoxy resin, phenol resin, vinyl ester resin, unsaturated polyester resin, bismaleide resin, cyanate resin, urethane resin, etc. The composition consisting of a so-called thermosetting resin is used, and an epoxy resin composition is particularly preferably used.

In the present invention, it is necessary that the matrix resin contains 20 to 70% by weight of the constituent element A, that is, an epoxy resin having a viscosity of 1 to 70 poise at 25 ° C. as a low viscosity component, preferably 3 parts. It is desirable that it is ˜50 poise. If the viscosity exceeds 70 poise, the drape property is deteriorated, the wettability becomes insufficient, and sufficient tack cannot be obtained, which is not preferable. If the viscosity is less than 1 poise, the prepreg retains its shape and becomes so-called stiff prepreg, which is not preferable.

The structure of the constituent element A is not particularly limited, and the following ones are preferably used. As the bisphenol F type epoxy resin (epoxy resin having bisphenol F as a precursor), "Epiclone"
(Registered trademark) 830 (viscosity at 25 ° C .: 30 to 40 poise (hereinafter referred to as p), Dainippon Ink and Chemicals, Inc.)
Manufactured), "Epicoat" 806 (viscosity at 25 ° C: 15 to 15
25p), "Epicoat" 807 (viscosity at 25 ° C: 3
0-45p, manufactured by Japan Epoxy Resin Co., Ltd., and hydrogenated bisphenol A type epoxy resin is TETRA.
DC (viscosity at 25 ° C .: 20 to 35 p, manufactured by Mitsubishi Gas Chemical Co., Inc.), “Denacol” EX-252 (viscosity at 25 ° C .: 22 p), “Denacol” EX- which is resorcin diglycidyl ether. 201 (viscosity at 25 ° C .: 2.
5p), "Denacol", a diglycidyl phthalate
EX-721 (viscosity at 25 ° C .: 9.8 p) (Nagase Kasei Co., Ltd.), alicyclic epoxy resin “Araldide” CY177 (viscosity at 25 ° C .: 6.5)
p), CY179 (viscosity at 25 ° C .: 3.5 p) (above, manufactured by Ciba Geigy Co., Ltd.), “Denacol” EX-314 (25) which is a triglycidyl ether of glycerin.
"Denacol" EX-41, a tetraglycidyl ether of pentaerythritol, with a viscosity of 1.7 p).
1 (viscosity at 25 ° C .: 8.0 p) (above, manufactured by Nagase Kasei Co., Ltd.), tetraglycidyl m-xylylenediamine TETRAD-X (viscosity at 25 ° C. 20-35)
p, manufactured by Mitsubishi Gas Chemical Co., Inc., “Sumi-epoxy” ELM100, which is triglycidyl-m-aminophenol.
(Viscosity at 25 ° C: 10 to 17p, Sumitomo Chemical Co., Ltd.
Manufactured), “Araldide” 0500 (viscosity at 25 ° C. 5.
5 to 8.5 p, manufactured by Ciba-Geigy Co., Ltd., "Sumiepoxy" ELN-125 (25) which is diglycidyl aniline.
Viscosity at 1 to 3 p, manufactured by Sumitomo Chemical Co., Ltd., and the like can be mentioned. It is also possible to use a plurality of these in combination.

At the same time, the softening point is 80 to 160 as the component B, that is, the solid component in the matrix resin.
It is necessary to contain 15 to 50% by weight of the epoxy resin at 0 ° C, and the softening point is preferably 90 to 150 ° C. If the softening point exceeds 160 ° C., it becomes difficult to be compatible with other components, which is not preferable. Further, if the softening point is less than 80 ° C., the tack is weakened and the change over time becomes large, which is not preferable.

The structure of the constituent element B is not particularly limited, and the following ones are preferably used. As the bisphenol A type epoxy resin, “Epicoat” 1003 (softening point: 89 ° C.), “Epicoat” 10
04 (softening point: 97 ° C.), “Epicoat” 1007 (softening point: 128 ° C.), “Epicoat” 1009 (softening point:
144 ° C) (above, manufactured by Japan Epoxy Resins Co., Ltd.)
And "Epototo" YD-014 (softening point: 91-10
2 ° C), "Epototo" YD-017 (softening point: 117
~ 127 ° C), "Epotote" YD-019 (softening point:
130-145 ° C) (above, manufactured by Tohto Kasei Co., Ltd.), "Epicoat" as a bisphenol F type epoxy resin
4004P (softening point: 85 ° C), "Epicoat" 400
7P (softening point: 108 ° C), "Epicoat" 4010P
(Softening point: 135 ° C.) (above, manufactured by Japan Epoxy Resins Co., Ltd.), oxazolidone ring type epoxy resin (softening point: 98 ° C., manufactured by Asahi Kasei Epoxy Co., Ltd.) and the like. It is also possible to use a plurality of these in combination.

The thermoplastic resin which is the constituent C of the present invention is blended with the matrix resin in order to control the viscoelasticity of the matrix resin and improve the prepreg characteristics.
The thermoplastic resin is not particularly limited as long as it is soluble in other components in the matrix resin.

The weight average molecular weight of the thermoplastic resin of the present invention must be in the range of 5,000 to 200,000, preferably 7,000 to 150,000, and more preferably 10,000 to 100,000. desirable. When the weight average molecular weight is within this range, a prepreg excellent in the balance between drapeability and impregnation is provided. When the weight average molecular weight exceeds 200,000, the impregnating property of the resin deteriorates, which is not preferable. On the other hand, if the weight average molecular weight is less than 5,000, the tack is weak and the prepreg is inferior in drapability, which is not preferable.

The constituent elements A, B and C exhibit the effect of the present invention only in the coexistence, and even if any one of them deviates from the predetermined amount, the effect is halved.

The amount of the constituent A added must be in the range of 20 to 70% by weight, preferably 25 to 65% by weight,
More preferably, the amount is 30 to 60% by weight. When the addition amount exceeds 70% by weight, the shape retention of the prepreg is impaired, which is not preferable. On the other hand, if the addition amount is less than 20% by weight, the tack is weak,
In addition, the prepreg is inferior in drape, which is not preferable.

The amount of component B added must be in the range of 15 to 50% by weight, preferably 17 to 45% by weight,
It is more preferable that the amount is 20 to 40% by weight. If the addition amount exceeds 50% by weight, the impregnating property of the prepreg becomes insufficient and the molding processability and the quality of the molded product are adversely affected, which is not preferable. On the other hand, the addition amount is 1
If the amount is less than 5% by weight, the tack becomes a weak prepreg, which is not preferable.

The amount of constituent C added must be in the range of 5 to 20% by weight, preferably 6 to 18% by weight, more preferably 7 to 15% by weight. When the addition amount is 5 to 20% by weight, a prepreg having excellent balance between tack and drape properties and having little change with time is provided. When the addition amount exceeds 20% by weight, the drape property of the prepreg deteriorates and the impregnation property of the resin deteriorates, which is not preferable. On the other hand, the addition amount is 5
If the amount is less than 10% by weight, the tack is weak and the prepreg has a large change over time, which is not preferable.

The form and arrangement of the carbon fibers used in the present invention are not particularly limited, and include, for example, unidirectionally aligned long fibers, single tows, woven fabrics, knits, non-woven fabrics, mats, and braided fibers. Although a structure is used, long fibers aligned in one direction are preferably used from the viewpoint of improving the fiber content and the quality of the molded product.

In order to manufacture lightweight sports equipment such as golf shafts and fishing rods, it is preferable to use carbon fiber having a high elastic modulus for the prepreg so that sufficient rigidity of the product can be expressed with a small amount of material. The elastic modulus of such a carbon fiber needs to be 280 GPa to 800 GPa, and is preferably 330 GPa to 600 GPa. When a resin composition according to the present invention is used when a prepreg made of carbon fibers having a high elastic modulus region is used, tackiness, drapeability or winding around a mandrel, handleability such as suppression of change over time, and further It has been found that it is possible to obtain excellent properties that were not obtained in the past in terms of quality and performance after curing.

The strength and elastic modulus of the obtained carbon fiber reinforced composite material largely depend on the carbon fiber content. Therefore, in the case of containing a certain amount of carbon fiber, the smaller the amount of matrix resin to be impregnated, the more the weight of the product can be reduced while maintaining the performance of the composite material and the final product almost constant. For such purposes, a prepreg having a high fiber content is preferably used. In this case, the fiber content of the prepreg is preferably 70 to 85% by weight, and more preferably 73 to 82% by weight. When making prepregs with high fiber content,
When the matrix resin of the present invention is used, tackiness, drapeability or wrapping around a mandrel, handleability such as suppression of aging, and further excellent properties not obtained with conventional resins in terms of quality and performance after curing. Can be obtained.

On the other hand, thinning of the prepreg also contributes to weight reduction and thickness reduction of the molded product. By thinning the prepreg,
Since the weight can be reduced without reducing the number of laminated layers, the weight can be reduced with almost no decrease in strength. However, there is a difficulty in that a resin film having a lower basis weight is required due to thinning, and impregnation becomes difficult. In this case, the basis weight of the prepreg is preferably 60 to 200 g / m2, and more preferably 70 to 170 g / m2. If the basis weight is less than 60 g / m2, the shape retention of the prepreg is greatly reduced, which is not preferable.
If the basis weight exceeds 200 g / m2, the fiber alignment inside the prepreg is likely to be disturbed, and it is difficult to obtain a high-performance fiber-reinforced composite material, which is not preferable.

When the matrix resin of the present invention is used when a prepreg having a low basis weight region is formed in this manner, tackiness, drapeability or winding around a mandrel, handleability such as suppression of aging, and further, after curing, It has been found that it is possible to obtain excellent properties in terms of quality and performance, which could not be obtained with conventional resins.

Further, various diluents, hardening aids, fillers, and other additives may be appropriately added to the matrix resin of the present invention.

As described above, it was found that when the matrix resin of the present invention is used, the prepreg has excellent tack / drape properties, winding properties, suppression of tack aging, and process passability. It has been found that such an effect can be obtained when exhibiting a characteristic rheological characteristic not found in That is, the temperature range around room temperature has a temperature range in which G'is relatively flat, and G'decreases significantly in the temperature range of 50 to 80 ° C.

In the present invention, the dynamic viscoelasticity of the resin composition is measured by cutting the resin composition into a plate and measuring the viscoelasticity by the DMA method to determine the viscoelasticity in the temperature range from the glass region to the room temperature. The measuring method is used. The matrix resin of the present invention has the following characteristic rheological properties.

That is, the matrix resin of the present invention is
G ′ in the dynamic viscoelasticity measurement at a measurement frequency of 0.5 Hz and 50 ° C. is preferably in the range of 500 to 50,000 Pa, more preferably 1000 to 20,000 Pa,
More preferably, it is desirable to be in the range of 1500 to 10,000 Pa. G'at 50 ° C is 500 to 5000
When it is in the range of 0 Pa, the prepreg develops sufficient tack. When G'exceeds 50000 Pa, the tack is too strong and the re-adhesion work during prepreg lamination becomes difficult, which is not preferable. If G'is less than 500 Pa, sufficient tack cannot be obtained, which is not preferable.

The matrix resin of the present invention has a ratio of G ′ at 10 ° C. to G ′ at 50 ° C. at a measuring frequency of 0.5 Hz in the range of 1000 to 50000, preferably 2
000 to 40,000, more preferably 3000 to 300
The range of 00 is desirable. G'and 5 at 10 ° C
When the G ′ ratio at 0 ° C. is in the range of 1,000 to 50,000, the prepreg has an excellent balance of tack and drape properties, and therefore the wrapping property around the mandrel becomes extremely good. The ratio of G'at 10 ° C to G'at 50 ° C is 200.
When it exceeds 00, the prepreg is inferior in drapability in spite of weak tackiness, and the winding property around the mandrel is extremely deteriorated, which is not preferable. Also, 10 ℃
If the ratio of G ′ at 50 ° C. to G ′ at 50 ° C. is less than 1000, the prepreg will have poor shape retention even though the tack is strong, and the re-adhesion work during prepreg lamination becomes extremely difficult, which is preferable. Absent. As described above, although the detailed mechanism is unknown, it is very effective to have a relatively flat region in the temperature range of 10 to 50 ° C. for both tack and drape.

Further, in the matrix resin of the present invention, it is preferable that the ratio of G'at 50 ° C. to G'at 80 ° C. at a measuring frequency of 0.5 Hz is in the range of 120 to 500, more preferably 140 to 500. It is desirable to be in the range of 400, more preferably 160 to 400. When the ratio of G ′ at 50 ° C. to G ′ at 80 ° C. is in this range, the impregnating property in the prepreg forming step is easily secured. Fifty
When the ratio of G ′ at 80 ° C. to G ′ at 80 ° C. exceeds 500, sufficient tack cannot be obtained because the resin does not remain on the surface of the prepreg, and the problem of the furnace falling during molding may occur. It is not preferable because it exists. Also, G'at 50 ° C and 80 ° C
If the ratio of G'is less than 120, the impregnating property of the prepreg becomes insufficient, which may adversely affect the moldability and the quality of the molded product, which is not preferable.

The glass transition temperature (hereinafter referred to as Tg) of the matrix resin of the present invention is preferably in the range of -5 to 7 ° C, more preferably -4 to 6 ° C, further preferably -3 to 5 ° C. It is desirable to be in the range. When the Tg of the matrix resin is within this range, proper tackiness is exhibited. When the Tg of the matrix resin exceeds 7 ° C., the wettability to the adherend is insufficient and tack is insufficient, which is not preferable. Further, when the Tg of the matrix resin is less than -5 ° C, the shape retention of the prepreg is deteriorated, which hinders processing and molding operations, which is not preferable.

Since the Tg of the prepreg is the same as the measured value of the Tg of the matrix resin, the Tg of the prepreg is
Thus, Tg of the matrix resin can be substituted.

Molding of the prepreg of the present invention is performed, for example, in the following manner. A fiber-reinforced composite material is obtained by laminating patterns obtained by cutting the prepreg and then heating and curing the resin while applying pressure to the laminate. Examples of the method of applying heat and pressure include a press molding method, an autoclave molding method, a vacuum pressure molding method, a sheet winding method, and an internal pressure molding method. Particularly, for sports equipment, the sheet winding method or the internal pressure molding method is preferable. Adopted.

The sheet winding method is a method of forming a cylindrical article by winding a prepreg around a mandrel, and is suitable for producing a rod-shaped body such as a golf shaft or a fishing rod. Specifically, a prepreg is wrapped around a mandrel and fixed so that the prepreg does not separate from the mandrel, or a tape-shaped thermoplastic resin film (wrapping tape) is applied to the outside of the prepreg in order to apply molding pressure to the prepreg. Is wrapped around, the resin is heated and cured in an oven, and then the core metal is extracted to obtain a cylindrical molded body.

In the internal pressure molding method, a preform in which a prepreg is wound around an inner pressure imparting body made of a thermoplastic resin is set in a mold, and high pressure air is introduced into the inner pressure imparting body to pressurize the mold simultaneously. It is a method of molding a fiber-reinforced composite material by heating. This internal pressure molding method is preferably used when molding a golf shaft or bat having a special shape, particularly a complicated shape such as a racket of tennis or badminton.

[0042]

EXAMPLES The present invention will be described in more detail below with reference to examples. The evaluation methods in the examples are as follows.

A. Dynamic viscoelasticity Dynamic viscoelasticity was measured using a dynamic analyzer RDAII type manufactured by Rheometrics. 10
G ′ at ℃ is 12.7 mm wide and 2 m thick than the resin composition.
A resin plate of m was prepared and evaluated under the conditions of a sample length of 35 mm, a measurement frequency of 0.5 Hz, and a heating rate of 1.5 ° C./min. G'at 50 ° C and 80 ° C uses a parallel plate with a radius of 25 mm, measurement frequency 0.5 Hz, temperature rising rate 1.5 ° C.
It was evaluated under the condition of / min.

B. Glass transition temperature (Tg) Each of the resin composition and the prepreg was measured by DSC under the conditions of a temperature rising rate of 10 ° C / min.

C. Tackability of prepregs The prepregs were pressure-bonded to each other and then peeled off, and the maximum load was divided by the sample area to determine the peeling strength T (MPa). "Instron" (registered trademark) 4 as a measuring device
Using a 201 type universal material testing machine (manufactured by Instron Japan Co., Ltd.), measurement was performed under the following conditions.・ Environment: 23 ± 2 ° C, 50 ± 5% RH ・ Sample: 50 × 50 mm ・ Load speed: 1 mm / min ・ Adhesive load: 0.11 MPa ・ Load time: 5 ± 2 sec ・ Peeling speed: 10 mm / min Tack test First, measure the tack immediately after peeling off the release paper and release film from the surface of the prepreg, and then peel off the release paper and release film and then leave the tack after leaving for 1 day in the measurement environment. It was measured.
The tack variation ratio was calculated by the following formula. Tack variation rate (%) = 100 × (initial tack T0-1-tuck T1 after standing for 1 day) / initial tack T0 D.I. Drapability of prepreg The drapability in this example was evaluated by measuring the flexural modulus of the prepreg. The flexural modulus can be measured by J
It was performed according to IS K7074 "Bending test method of fiber reinforced plastic". "Instron" as a measuring device
Using a Model 4201 universal material testing machine (manufactured by Instron Japan Co., Ltd.), measurement was performed under the following conditions.・ Environment: 23 ± 2 ° C, 50 ± 5% RH ・ Sample: 85mm (fiber direction) × 15mm ・ Load speed: 5mm / min ・ Distance between fulcrums: 40mm ・ Indenter diameter: 4mmφ of the obtained 0 ° bending elastic modulus The reciprocal D (GPa-1) was used as an index of drapability.

The drape test is conducted from the surface of the prepreg.
The drapeability immediately after peeling off the release paper and the release film was measured.

E. Wrapability of prepreg around mandrel The wrapability of prepreg around the mandrel was evaluated as follows. A prepreg left for 3 days in an atmosphere of a temperature of 23 ° C and a humidity of 50% has a diameter of 10 m.
The prepreg was wound around a SUS cylinder having a length of m and a length of 1000 mm so that the direction of aligning the reinforcing fibers was at an angle of 45 ° with respect to the longitudinal direction of the cylinder, and the winding state of the prepreg after leaving for 15 minutes was observed. The prepregs are classified as follows according to the maximum peeling height at the winding end portion, and the peeling lengths are added for each of S, M, and L. Furthermore, the winding index on the mandrel was calculated by the following formula, and the calculated index was used as the winding index. S: Maximum peeling height is less than 2 mm M: Maximum peeling height is 2 mm or more and less than 4 mm L: Maximum peeling height is 4 mm or more Wrapability index on mandrel = S + 2M + 4L F. Impregnation of prepreg The impregnation of the finished prepreg was visually and tactilely felt.
A graded evaluation was made (very good: ⊚, good: ◯, slightly unimpregnated part: Δ, unimpregnated part: x, poor impregnation: xx).

In this example, as the epoxy resin, a liquid bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., "Epicoat" 828), a solid bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.) were used. , "Epicoat" 1001), solid bisphenol A type epoxy resin (Japan Epoxy Resin Co., Ltd., "Epicoat" 1004), solid bisphenol A type epoxy resin (Japan Epoxy Resin Co., Ltd., "Epicoat" 1009) Liquid bisphenol F type epoxy resin (Japan Epoxy Resin Co., Ltd.)
"Epicoat" 807), solid bisphenol F
Type epoxy resin (Japan Epoxy Resin Co., Ltd.,
"Epicoat" 4004P), triglycidyl-m-aminophenol (Sumitomo Chemical Co., Ltd., "Sumi-epoxy" ELM100), triglycidyl ether of glycerin (Nagase Kasei Co., Ltd., "Denacol" EX-
314) was used. In addition, as the thermoplastic resin, polyvinylpyrrolidone (manufactured by BASF Japan Ltd., “Luviscor” K-30; weight average molecular weight 45,000), polyvinylpyrrolidone (manufactured by BASF Japan Ltd., “Luviscor” K-). 90; weight average molecular weight 1.2 million), polyvinyl formal (manufactured by Chisso Corporation, "Vinilec"K;
Weight average molecular weight 20,000), polymethylmethacrylate (Matsumoto Yushi-Seiyaku Co., Ltd., "Matsumoto Microsphere")
M: weight average molecular weight 1,000,000) was used. Further, dicyandiamide as a curing agent, and DC as a curing aid.
MU was used. (Examples 1 to 3) (1) Preparation of matrix resin composition The raw materials shown in Table 1 were kneaded using a kneader to prepare a matrix resin composition. (2) Preparation of prepreg The resin composition was applied onto release paper using a reverse roll coater to prepare a resin film. Next, a carbon fiber “Treca” (registered trademark) T800H-12K (Toray Industries, Inc.) having a tensile elastic modulus of 294 GPa arranged in one direction.
Resin film on both sides of the
C., 0.4 MPa) to impregnate the resin into a unidirectional prepreg having a basis weight of 220 g / m 2 and a fiber weight content of 68%.

The impregnating property of these prepregs, tack drape, and winding property around the mandrel were all good. Moreover, the change in tack with time was small.
The results are shown in Table 1. (Example 4) Carbon fiber "Torayca" M40SC-12K (manufactured by Toray Industries, Inc.) having a tensile elastic modulus of 392 GPa was used, and the basis weight of the prepreg was 150 g / m2 and the fiber weight content was 7.
A prepreg was produced in the same manner as in Example 3 except that the prepreg was 5%.

This prepreg was excellent in drapeability and extremely good in winding ability around a mandrel. (Examples 5 to 8) The raw materials shown in Table 1 were kneaded using a kneader to prepare a matrix resin composition. Furthermore, a prepreg was produced in the same manner as in Example 4.

The impregnating property of these prepregs, the tack drape, and the winding property around the mandrel were all good. Moreover, the change in tack with time was small.
The results are shown in Table 1. (Comparative Examples 1 to 3) The raw materials shown in Table 2 were kneaded using a kneader to prepare a matrix resin composition. Furthermore, a prepreg was produced in the same manner as in Examples 1 to 3.

These prepregs were inferior in impregnating property during preparation of prepregs as compared with Examples 1 to 3. The results are shown in Table 2. (Comparative Examples 4 and 5) (1) Preparation of Matrix Resin Composition The raw materials shown in Table 2 were kneaded using a kneader to prepare a matrix resin composition. Furthermore, a prepreg was produced in the same manner as in Examples 1 to 3.

These prepregs were inferior in tack drape and mandrel wrapping property to Examples 1 to 3. The results are shown in Table 2. (Comparative Example 6) The raw materials shown in Table 2 were kneaded using a kneader to prepare a matrix resin composition. Further, prepregs were produced by the same method as in Examples 4-8.

These prepregs were inferior in tack drape and mandrel wrapping property to Example 4. The results are shown in Table 2.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

According to the present invention, by optimizing the rheology of each temperature region of a resin composition,
Excellent impregnation of resin into reinforcing fibers during molding, and the finished prepreg has excellent tack, drape, and wrapping properties, as well as little change over time, so high-quality, high-performance fiber reinforced regardless of working environment and conditions. A composite material can be provided.

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Claims (7)

[Claims] 1. A prepreg comprising a carbon fiber having a tensile elastic modulus of 280 to 800 GPa impregnated with a matrix resin containing at least the following constituent elements A to C. A. Epoxy resin having a viscosity of 1 to 70 poises at 25 ° C:
20-70% by weight B.I. Epoxy resin having a softening point of 80 to 160 ° C .: 15 to 5
0 wt% C.I. Thermoplastic resin soluble in matrix resin having a weight average molecular weight of 5,000 to 200,000: 5 to 20% by weight 2. The prepreg according to claim 1, wherein the prepreg contains 70 to 85% by weight of fibers. 3. The prepreg has a basis weight of 60 to 200 g / m.
The prepreg according to claim 1 or 2, wherein the prepreg is 2. 4. A prepreg comprising a carbon fiber having a tensile elastic modulus of 280 to 800 GPa impregnated with a matrix resin satisfying the following conditions a and / or b. a. Storage elastic modulus (hereinafter abbreviated as G ′) measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. is 500 to 50,000 Pa b. The ratio of G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 10 ° C. and G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. is 1000 to 50000. 5. The prepreg according to claim 1, wherein the matrix resin satisfies the following conditions a and / or b. a. G measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. is 500 to 50,000 Pa b. The ratio of G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 10 ° C. and G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. is 1000 to 50000. 6. The prepreg according to claim 4 or 5, wherein the matrix resin satisfies the following conditions.
The ratio of G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 50 ° C. and G ′ measured by dynamic viscoelasticity at a measurement frequency of 0.5 Hz and 80 ° C. is 120 to 500. 7. The prepreg according to claim 4, which has a glass transition temperature of −5 to 7 ° C.