JP2005313607A - Reinforcing fiber base material, prepreg, fiber-reinforced plastic and manufacturing method of fiber-reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcing fiber base material and a prepreg each capable of making compression strength after impact and compression strength after water absorption under an environment of high temperature compatible with each other, and to provide an easily manufactured fiber reinforced plastic and a method of manufacturing the fiber reinforced plastic. <P>SOLUTION: In the reinforcing fiber base material containing a component element [A] and a component element [B], the component element [B] is a reinforcing fiber base material having a bending modulus of 2.0 to 5.0 GPa at 23°C and containing a crystalline polyamide showing water absorption of less than 1.2% after underwater immersion at 23°C for 24 hours. The fiber-reinforced plastic can be made by using the reinforcing fiber base material. The reinforcing fiber [A] or [B] or/and a film are also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reinforced fiber substrate and a prepreg that can easily obtain a fiber reinforced plastic excellent in compressive strength after impact and compressive strength in a high temperature environment after water absorption. The present invention also relates to a fiber reinforced plastic excellent in compressive strength after impact and compressive strength in a high temperature environment after water absorption, and a method for producing the same.

  Fiber reinforced plastic made of glass fiber, carbon fiber, aramid fiber, alumina fiber, boron fiber and other reinforced fibers, and cured products of matrix resins such as unsaturated polyester resin, vinyl ester resin, epoxy resin and phenol resin are lightweight. In addition, because of its excellent mechanical properties such as strength and elastic modulus, it is widely used in aerospace applications, sports equipment applications and general industrial applications.

  When fiber reinforced plastic is used as a structural member such as an aircraft, it is necessary to have excellent impact resistance. An important index of impact resistance is post-impact compressive strength. In fiber reinforced plastics, there is a phenomenon that the compressive strength of the structural member is reduced due to tool dropping or pebbles collision, but if the compressive strength is significantly reduced, it cannot be used as the structural member. Therefore, in such a structural member, it is important that the compressive strength after impact is excellent.

  In order to increase the compressive strength after impact of the fiber reinforced plastic, a method is known in which particles, fibers, or films made of a thermoplastic resin are disposed between the reinforced fiber layers of the fiber reinforced plastic. As the thermoplastic resin, polyamide is often used because of excellent adhesion between the reinforcing fiber and the cured product of the matrix resin.

  When this method is used, it is important that the particle diameter, the fiber diameter, and the film thickness placed between the layers are small. As the particle diameter, fiber diameter, and film thickness increase, the interlayer thickness increases and the volume of the interlayer portion increases. Since the volume of the reinforcing fiber does not change, the volume content of the reinforcing fiber, that is, the fiber volume content (Vf) decreases when the volume of the interlayer portion increases. When the fiber volume content decreases, the mechanical properties such as strength and elastic modulus of the fiber reinforced plastic deteriorate.

  Conventionally, polyamide 6 and polyamide 12, which are crystalline polyamides, grillamide TR-55 (manufactured by Mitsubishi Engineering Plastics) and Trogamide-T (manufactured by Daicel Huls) are used as a method of using fine particles made of polyamide. ), It is proposed to obtain a fiber reinforced plastic with excellent compressive strength after impact by using prepreg in which fine particles made of amorphous polyamideimide Torlon (made by Amoco Engineering Polymers) are distributed in a matrix resin. (See Patent Document 1). In particular, it has been shown that a remarkable effect can be obtained by distributing fine particles in a high concentration between layers. Moreover, in this method, it is possible to obtain a fiber reinforced plastic having a large fiber volume content by using particles having a small particle diameter. However, this method has a problem that it is not easy to produce fine particles.

  On the other hand, the method using a fiber or film made of polyamide has an advantage that the production of the fiber or film is relatively easy as compared with the case of using fine particles.

  Polyamide 66, polyamide 612, polyamide 11, polyamide 12, non-crystalline polyamide Grillamide TR-55, Trogamide-T (manufactured by Daicel Huls), amorphous It has been proposed to obtain a fiber reinforced plastic having excellent compressive strength after impact by arranging fibers made of Torlon (made by Amoco Engineering Polymers Co., Ltd.), which is a functional polyamideimide, in a certain direction in the vicinity of the surface layer of the prepreg ( Patent Literature 2 to Patent Literature 7).

  In addition, a woven fabric composed of polyamide 6, which is crystalline polyamide, polyamide 66, polyamide 612, polyamide 11, polyamide 12, grill amide TR-55, which is amorphous polyamide, trogamide-T, and tolon which is amorphous polyamide imide. It has been proposed to obtain a fiber reinforced plastic having excellent compressive strength after impact by arranging the fiber structure in the vicinity of the surface layer of the prepreg (see Patent Document 8 and Patent Document 9).

  It has also been proposed to obtain a fiber-reinforced plastic having excellent compressive strength after impact by arranging a knitted fiber structure made of polyamide 6 or polyamide 66, which is a crystalline polyamide, in the vicinity of the surface layer of the prepreg. (See Patent Document 10).

  Further, a non-woven fiber structure composed of polyamide 6, polyamide 66, polyamide 12, which is crystalline polyamide, and grill amide TR-55, which is amorphous polyamide, is disposed in the vicinity of the surface layer of the prepreg so that the compressive strength after impact is increased. It is proposed that an excellent fiber-reinforced plastic can be obtained (see Patent Document 11).

  However, these methods have another problem as follows. It is still not very easy to produce small diameter fibers and thin films when using amorphous polyamides GRILLAMID TR-55, Trogamide-T, and amorphous polyamideimide Torlon. That is.

  The following reasons can be considered as this cause. When trying to manufacture small diameter fibers by melt spinning, which is a general synthetic fiber manufacturing method, or manufacturing thin films by T-die film molding, which is a general thermoplastic film manufacturing method. In this case, it is necessary that the elongational viscosity at the time of melting is low. This is because if the elongational viscosity at the time of melting is high, melt fracture tends to occur and it becomes difficult to produce fibers and films. In order to lower the elongational viscosity at the time of melting, it is preferable to use a thermoplastic resin having a small molecular weight. When a crystalline thermoplastic resin is used, sufficient strength and elastic modulus are easily obtained even if the molecular weight is small, reflecting that the crystal portion has high strength and high elastic modulus. However, when an amorphous thermoplastic resin is used, since the ratio of strength and elastic modulus depends on the entanglement of molecular chains is large, it is difficult to obtain sufficient strength and elastic modulus when the molecular weight is small. In other words, the amorphous thermoplastic resin has a problem that it is difficult to achieve both physical properties such as strength and elastic modulus, ease of fiber production by melt spinning, and film production by T-die film molding. . Amorphous polyamides such as Grillamide TR-55, Trogamide-T, and Amorphous polyamideimide Torlon have sufficient strength and elastic modulus, but they can produce small diameter fibers and thin films. Was still difficult and accompanied by difficulties.

  On the other hand, when a crystalline polyamide such as polyamide 6, polyamide 66, polyamide 612, polyamide 11 and polyamide 12 is used, a fiber having a small diameter and a film having a small film thickness can be easily produced. However, when fiber reinforced plastics using these crystalline polyamides are used as structural members such as aircraft, the compressive strength under high temperature environment after water absorption, which is an important characteristic as well as the compressive strength after impact, becomes insufficient. .

As described above, in order to increase the compressive strength after impact of the fiber reinforced plastic, the method of arranging the fiber or film made of the thermoplastic resin between the layers of the fiber reinforced plastic has hitherto been easy to manufacture and also absorbs water. A thermoplastic resin material that has sufficient compressive strength in a high-temperature environment has not been found.
US Pat. No. 5,028,478 Japanese Patent No. 3137671 Japanese Patent No. 3137733 Japanese Patent No. 3238719 JP-A-5-329838 JP-A-6-25917 JP-A-6-49709 Japanese Patent No. 3145182 Japanese Patent No. 3145183 JP-A-7-149927 Japanese Patent No. 3387100

  An object of the present invention is to provide a reinforced fiber base material and a prepreg that can achieve both compression strength after impact and compression strength in a high-temperature environment after water absorption, and can be easily manufactured, in view of the background of such prior art. There is. Another object of the present invention is to provide a fiber-reinforced plastic that can achieve both the compressive strength after impact and the compressive strength in a high-temperature environment after water absorption and can be easily manufactured, and a method for manufacturing the same.

In order to solve the above problems, the present invention employs the following means. That is, the reinforcing fiber base material of the present invention is a reinforcing fiber base material including the following constituent element [A] and constituent element [B], wherein the constituent element [B] has a flexural modulus at a temperature of 23 ° C. A reinforcing fiber base material comprising a crystalline polyamide having a water absorption of less than 1.2% after immersion in water at a temperature of 23 ° C. in a range of 2.0 to 5.0 GPa.
[A] Reinforcing fiber [B] Fiber or / and film.

And said reinforcing fiber base material of this invention has the following preferable aspect.
(A) The constituent element [B] includes a crystalline polyamide having an aromatic ring.
(B) The constituent element [B] includes a crystalline polyamide having a melting point within a temperature range of 200 to 350 ° C.
(C) Said component [B] contains crystalline polyamide shown by the following general formula (I).

(Wherein, m is an integer from 1 to 12, and n is an integer)
(D) The component [B] is distributed on one or both surfaces.
(E) The constituent element [B] is a fiber structure in a woven, knitted or non-woven shape.

The prepreg of the present invention is a prepreg comprising the following component [A], component [B] and component [C], and the component [B] has a flexural modulus at a temperature of 23 ° C. A prepreg comprising a crystalline polyamide having a water absorption of less than 1.2% after immersion in water at a temperature of 23 ° C. in a range of 2.0 to 5.0 GPa.
[A] Reinforcing fiber [B] Fiber or / and film [C] Matrix resin.

And said prepreg of this invention has the following preferable aspect.
(F) The constituent element [B] includes a crystalline polyamide having an aromatic ring.
(G) The constituent element [B] includes a crystalline polyamide having a melting point within a temperature range of 200 to 350 ° C.
(H) Said component [B] contains crystalline polyamide represented by the following general formula (I).

(Where m is an integer from 1 to 12, and n is an integer))
(I) The constituent element [B] is distributed in the vicinity of one or both surface layers.
(J) The above-mentioned component [B] is a fiber structure in the form of a woven fabric, a knitted fabric or a non-woven fabric.

The fiber reinforced plastic of the present invention is a fiber reinforced plastic including the following component [A], component [B] and component [D], wherein the component [B] is at a temperature of 23 ° C. A fiber-reinforced plastic comprising a crystalline polyamide having a flexural modulus of 2.0 to 5.0 GPa and a water absorption rate of less than 1.2% after immersion in water at a temperature of 23 ° C. for 24 hours. is there.
[A] Reinforced fiber [B] Fiber and / or film [D] Matrix resin cured product The method for producing a fiber-reinforced plastic according to the present invention includes a liquid heat applied to the above-mentioned reinforcing fiber substrate disposed in a mold. After impregnating a curable resin composition, the method is a method for producing a fiber-reinforced plastic, which is heated and cured.

  By using the reinforced fiber base material or prepreg of the present invention, it is possible to obtain a fiber reinforced plastic having both the compression strength after impact necessary for a structural member such as an aircraft and the compression strength in a high temperature environment after water absorption. Moreover, crystalline polyamide fibers or films are easy to manufacture and contribute to cost reduction.

  The present invention uses a specific crystalline polyamide in a method of disposing a fiber or / and a film containing a thermoplastic resin between layers of a fiber reinforced plastic in order to increase the compressive strength after impact of the fiber reinforced plastic. It is possible to easily produce fibers with small diameters and films with small film thickness, and to obtain fiber reinforced plastics that are excellent not only in compressive strength after impact but also in compressive strength under high temperature environment after water absorption. Headline, achieved.

  So far, it has been known that by using crystalline polyamide, it is easy to produce a fiber having a small diameter and a film having a small film thickness, and a fiber reinforced plastic having excellent compressive strength after impact can be obtained. It was thought that the compressive strength under the high temperature environment was lowered.

  As a result of examining the cause of the decrease in compressive strength in a high-temperature environment after water absorption, the present inventors have found that the elastic modulus and water absorption of crystalline polyamide indicate that the elasticity of the interlayer portion of the fiber-reinforced plastic in the high-temperature environment after water absorption. We found that there is a large correlation with the rate. In addition, crystalline polyamides that have been used in the past have an insufficient elastic modulus or a large water absorption rate, so that the elastic modulus of the interlayer portion of the fiber-reinforced plastic in a high-temperature environment after water absorption decreases. I also found out. When the elastic modulus of the interlayer portion is lowered, the reinforcing fibers are likely to buckle and break, and the compressive strength of the fiber reinforced plastic is lowered. Based on this result, the present inventors have excellent compressive strength in a high-temperature environment after water absorption, even if it is a crystalline polyamide, if a crystalline polyamide having a high elastic modulus and a low water absorption rate is used. As a result of studying various crystalline polyamides on the assumption that fiber reinforced plastics can be obtained, the present invention has been achieved.

  Specific examples of the reinforcing fiber used in the present invention include glass fiber, carbon fiber, aramid fiber, alumina fiber, and boron fiber. Among these, carbon fibers are preferably used because they have excellent properties of high strength and high elastic modulus while being lightweight.

  As the reinforcing fibers, both short fibers and long fibers can be used. Especially, since the intensity | strength and elastic modulus of the fiber reinforced plastic obtained are excellent, it is preferable to use the reinforced fiber of 5 cm or more in length.

  Specific examples of the arrangement structure of the reinforcing fibers include those having an arrangement structure such as a single direction, a random direction, a sheet shape, a mat shape, a woven shape, and a knitted shape. Especially, since the intensity | strength and elastic modulus of the fiber reinforced plastic which are obtained are excellent, the thing of the arrangement | sequence structure aligned in the single direction is preferable. Moreover, since it is excellent in handleability, the thing of a textile-like arrangement structure is also used preferably.

  The polyamide in the crystalline polyamide used in the present invention means a polymer having an amide bond in the main chain. The crystallinity in the crystalline polyamide used in the present invention is the heat of crystal melting of 10 J / g or more when a temperature rise measurement is performed at 10 ° C./min using a differential scanning calorimeter (DSC). Means something. A polymer having crystallinity reflects the high strength and high elastic modulus of the crystal portion, and it is easy to obtain high strength and high elastic modulus. For this reason, even when a low molecular weight polymer, which is relatively easy to produce a fiber having a small diameter and a film having a small film thickness, is used, there is an advantage that high strength and a high elastic modulus are easily obtained.

  The crystalline polyamide used in the present invention needs to have a flexural modulus at a temperature of 23 ° C. measured in accordance with ASTM D790-97 within a range of 2.0 to 5.0 GPa. It is preferably within the range of 5 to 4.5 GPa. If the flexural modulus is less than 2.0 GPa, the elastic modulus of the fiber reinforced plastic interlayer between the water-absorbing high-temperature environment decreases, and the reinforcing fibers are likely to buckle and break. Insufficient strength. However, if the flexural modulus is higher than 5.0 GPa, the toughness of the interlayer portion of the fiber reinforced plastic is insufficient, and the compressive strength after impact is lowered.

  In order to make the flexural modulus in the range of 2.0 to 5.0 GPa, the molecular chain of the crystalline polyamide needs to be moderately rigid. In order to make the molecular chain rigid, it is preferable to have an aromatic ring in the molecular chain.

  Further, the crystalline polyamide of the present invention needs to have a water absorption rate of less than 1.2% after 24 hours of immersion in water at a temperature of 23 ° C. measured in accordance with ASTM D570-95. It is preferable that it is less than%. If the water absorption is 1.2% or more, the elastic modulus of the fiber reinforced plastic between the layers in the high-temperature environment after water absorption is insufficient, and the reinforcing fibers are likely to buckle and break, and compression in the high-temperature environment after water absorption. Strength will fall.

  In order to make the water absorption rate less than 1.2%, it is necessary that the molecular chain of the crystalline polyamide contains a lot of small polar groups. Specific examples of the small polar group include a linear aliphatic group and a cyclic aliphatic group such as an alkylene group and a cycloalkylene group.

  The crystalline polyamide used in the present invention preferably has an aromatic ring in the molecular chain. When an aromatic ring is included in the molecular chain, the molecular chain becomes rigid and a high elastic modulus is easily obtained. Specific examples of the crystalline polyamide having an aromatic ring in the molecular chain include polyamides having a group having a structure of the following general formulas (II) to (V) and an amide group.

  The crystalline polyamide used in the present invention preferably contains a polyamide represented by the following general formula (I). The reason is unknown, but the polyamide having this structure can achieve both high elastic modulus and low water absorption. Especially, in order to obtain a moderately high elastic modulus, it is preferable that the m number of methylene chain repeats is in the range of 1-6. When m is larger than 6, the molecular chain becomes flexible and the elastic modulus may be insufficient.

(Where n is an integer)
The crystalline polyamide used in the present invention preferably has a melting point within a temperature range of 200 to 350 ° C, and more preferably has a melting point within a temperature range of 200 to 300 ° C. When the melting point is lower than 200 ° C., the crystalline polyamide is partially melted during the molding of the fiber reinforced plastic, and the strength of the resulting fiber reinforced plastic may become unstable due to variations in molding conditions. On the other hand, when the melting point is higher than 350 ° C., it may be difficult to produce a fiber having a small diameter and a film having a small film thickness.

Specific examples of the crystalline polyamide used in the present invention include:
Polyamide 610 (crystalline polyamide represented by the following general formula (VI), flexural modulus 2.2 GPa at a temperature of 23 ° C., water absorption 0.5% after immersion in water at a temperature of 23 ° C., melting point 213 ℃)

(Where n is an integer)
Polyamide 6T (crystalline polyamide represented by the following general formula (VII), flexural modulus of 3.0 GPa at a temperature of 23 ° C., water absorption of 0.3% after 24 hours of immersion in water at a temperature of 23 ° C.)

(Where n is an integer)
Polyamide 9T (crystalline polyamide represented by the following general formula (VIII), flexural modulus 2.5 GPa at 23 ° C., water absorption 0.2% after 24 hours of immersion in water at 23 ° C., melting point 308 ° C.)

(Where n is an integer)
MX nylon (crystalline polyamide represented by the following general formula (IX), flexural modulus 4.5 GPa at a temperature of 23 ° C., water absorption 0.3% after immersion in water at a temperature of 23 ° C., melting point 243 ° C. )

Etc.

  In addition, the crystalline polyamide used in the present invention may be used alone or in combination. Along with other thermoplastic resins different from crystalline polyamides such as amorphous polyamide, polyamideimide, polycarbonate, polysulfone, polyacetal, polyphenylene ether, polyphenylene sulfide, polyarylate, polyetherimide, polyethersulfone and polyetherketone It may be used. In this case, the ratio of the crystalline polyamide used in the present invention to the entire thermoplastic resin is preferably 50 wt% or more, and more preferably 70 wt% or more.

  In the present invention, when the constituent element [B] is a fiber, both a short fiber and a long fiber can be used as the fiber. Moreover, when component [B] is a fiber, it is preferable that the diameter of a fiber exists in the range of 1-15 micrometers, More preferably, it exists in the range of 1-10 micrometers. If the fiber diameter is smaller than 1 μm, the fiber may not be easily manufactured. However, when the fiber diameter is larger than 15 μm, the thickness between layers becomes larger than necessary, and the fiber volume content (Vf) decreases, so that the mechanical properties such as strength and elastic modulus of the fiber reinforced plastic deteriorate. There is.

  In addition, when the constituent element [B] is a fiber, various forms of the constituent element [B] are possible. Specifically, the configuration in which the component [B] is aligned in one direction, the configuration in which the component [B] is woven, the configuration in which the configuration [B] is knitted, and the configuration Examples include a non-woven form in which [B] is randomly arranged on a plane. Especially, since the handling is easy, the form of the fiber structure of a woven fabric shape, a knitted shape, and a nonwoven fabric shape is preferable. Furthermore, since the thing with uniform thickness is comparatively easy to manufacture, the form of a nonwoven fabric is preferable.

When the component [B] is a woven, knitted or non-woven fiber structure, the weight per unit area of the component [B], that is, the basis weight may be in the range of 1 to ²⁰ g / m ^2. Preferably, it is in the range of 1 to 10 g / m ² . When the basis weight is larger than 20 g / m ² , the interlayer thickness becomes unnecessarily large and the fiber volume content (Vf) becomes small, so that the mechanical properties such as strength and elastic modulus of the fiber reinforced plastic may be lowered. is there. However, if the basis weight is less than 1 g / m ² , the amount of the crystalline polyamide between layers is small, and the compressive strength after impact of the fiber reinforced plastic may be insufficient.

  In this invention, when said structural element [B] is a film, it is preferable that the thickness of a film exists in the range of 1-60 micrometers, More preferably, it exists in the range of 1-40 micrometers. If the thickness is larger than 60 μm, the interlayer thickness becomes unnecessarily large and the fiber volume content (Vf) becomes small, so that mechanical properties such as strength and elastic modulus of the fiber reinforced plastic may be deteriorated. However, if the thickness is smaller than 1 μm, the amount of the crystalline polyamide between layers is small, and the compressive strength after impact of the fiber reinforced plastic may be insufficient.

  Further, when the component [B] is a film, it can be used in a form in which a slit film is aligned in one direction, or a form in which a hole is formed in the film.

  Moreover, as a matrix resin used by this invention, both a thermosetting resin and a thermoplastic resin can be used. Among these, the use of a thermosetting resin is advantageous in that a cured product having excellent mechanical properties such as heat resistance, strength, and elastic modulus can be obtained and molding can be performed at a relatively low temperature. preferable. Specific examples of the thermosetting resin include unsaturated polyester resin, vinyl ester resin, epoxy resin, and phenol resin. Of these, it is preferable to use an epoxy resin because of its excellent adhesion to reinforcing fibers and crystalline polyamide.

  When an epoxy resin is used as the matrix resin used in the present invention, it is used in combination with a curing agent. The curing agent may be a compound having an active group that reacts with the epoxy group of the epoxy resin, and specific examples thereof include polyamines, acid anhydrides, phenols, and mercaptans. In addition, basic compounds such as tertiary amines and imidazoles, which are initiators for homopolymerization of epoxy resins, or acidic compounds such as amine complexes of boron trifluoride can also be used.

In addition, the matrix resin used in the present invention includes other components such as polyamide, polyamideimide, polycarbonate, polysulfone, polyacetal, polyphenylene ether, polyphenylene sulfide, polyarylate, polyetherimide, polyethersulfone, and polyetherketone. It is also possible to mix and modify a plastic resin, inorganic fine particles such as fine powdered silica and an elastomer, etc. The matrix resin used in the present invention was measured in accordance with ASTM D790-97 of a cured product. The flexural modulus at a temperature of ° C is preferably in the range of 3.0 to 5.0 GPa, and more preferably in the range of 3.2 to 5.0 GPa. If the flexural modulus is less than 3.0 GPa, the elastic fiber around the reinforcing fiber including the interlayer part of the fiber reinforced plastic under the high temperature environment after water absorption, that is, the elastic modulus of the matrix part is insufficient, and the reinforcing fiber is likely to buckle and break. Thus, the compressive strength in a high temperature environment may be reduced after water absorption. However, if the flexural modulus is greater than 5.0 GPa, the toughness of the matrix portion including the interlayer portion of the fiber reinforced plastic may be insufficient, and the compressive strength after impact may decrease.

  The matrix resin used in the present invention preferably has a water absorption rate of less than 1.2% after 24 hours of immersion in water at a temperature of 23 ° C. measured according to ASTM D570-95 of a cured product obtained by curing. More preferably, it is less than 1.0%. When the water absorption rate is 1.2% or more, the elastic fiber around the reinforcing fiber including the interlayer part of the fiber reinforced plastic under the high temperature environment after water absorption, that is, the elastic modulus of the matrix part is insufficient, and the reinforcing fiber is likely to buckle and break. Thus, the compressive strength in a high temperature environment may be reduced after water absorption.

  The matrix resin used in the present invention preferably has a tensile elongation of 3% or more at a temperature of 23 ° C. measured according to ASTM D638-91 of a cured product obtained by curing, More preferably, it is 5% or more. When the tensile elongation is less than 3%, the toughness around the reinforcing fiber including the interlayer portion of the fiber reinforced plastic, that is, the matrix portion may be lowered, and the compressive strength after impact may be lowered.

  The reinforcing fiber substrate of the present invention includes the following component [A] and component [B], and the component [B] has a flexural modulus of 2.0 to 5.0 GPa at a temperature of 23 ° C. And a crystalline polyamide having a water absorption rate of less than 1.2% after immersion in water at 23 ° C. for 24 hours.

[A] Reinforcing fiber [B] Fiber or / and film As the reinforcing fiber substrate of the present invention, a fiber reinforced plastic having excellent compressive strength after impact is obtained in which constituent elements [B] are distributed at high density between layers. Therefore, it is preferable that the component [B] is distributed on one or both surfaces. Here, the component [B] is distributed on the surface. When the average thickness of the reinforcing fiber layer is t, 90% of the component [B] is formed in a region having a thickness of 0.3 t vertically from the surface of the reinforcing fiber layer. Means more than%.

  Evaluation of the distribution state of the component [B] in the reinforcing fiber substrate can be performed as follows. First, the cross section of the reinforcing fiber base is enlarged 200 times or more, and a photograph of 200 mm × 200 mm or more is taken. First, the average thickness (t) of the reinforcing fiber layer is obtained using this cross-sectional photograph. The thickness of the reinforcing fiber layer is measured at at least five points arbitrarily selected on the photograph, and the average is taken. Next, the area of the component [B] existing in the region having a thickness of 0.3 t from the upper and lower sides of the surface of the reinforcing fiber layer is quantified on both sides of the reinforcing fiber base, and the entire width of the reinforcing fiber base is measured. By quantifying the total area of the existing component [B] and taking the ratio, the ratio of the component [B] existing in the region having a thickness of 0.3 t from the surface of the reinforcing fiber layer is calculated. The area quantification can also be performed by a gravimetric method or image processing using an image analyzer. In order to eliminate the influence of partial distribution variation, this evaluation should be performed over the entire width of the obtained photo, and the same evaluation should be made for five or more arbitrarily selected photos, and the average must be taken. is there.

  Since the reinforcing fiber base material of the present invention is excellent in handleability, the component [A] and the component [B] are obtained by a method using an adhesive material containing a thermoplastic resin or a thermosetting resin, a method such as stitching or punching. ] Are preferably integrated.

  As a method for producing a fiber reinforced plastic using the reinforced fiber substrate of the present invention, a hand lay-up method, a reinforced fiber substrate disposed in a mold is impregnated with a liquid thermosetting resin composition, and then heated. Then, a curing method such as a so-called RTM (Resin Transfer Molding) method can be used. Especially, since it has the advantage that a complicated-shaped member can be manufactured efficiently, it is preferable to use the RTM method.

  Next, the manufacturing method of the fiber reinforced plastic by RTM method using the reinforced fiber base material of this invention is demonstrated in order of a process.

1. Step of preparing reinforcing fiber substrate The reinforcing fiber substrate of the present invention may be cut and laminated into a desired shape. Furthermore, after cutting and laminating, a method in which a reinforcing fiber substrate is shaped into a desired shape in advance by a method using an adhesive containing a thermoplastic resin or a thermosetting resin, a method using a stitch, or the like may be used. . Moreover, you may use what combined the reinforcing fiber and other materials, such as a core material.

2. Mold Preparation and Impregnation Step In the RTM method of the present invention, the structure of the mold is not limited, but a closed mold made of a rigid material or an open mold made of a rigid material and a bagging film can be used. As the rigid material, for example, carbon steel, alloy steel, cast iron, metal such as aluminum and aluminum, FRP (Fiber Reinforced Plastic), wood, plaster and the like can be used. Moreover, as a material for the bagging film, for example, polyamide, polyimide, polyester, silicone, or the like can be used.

  When using a sealed mold, it is usually performed by pressurizing and clamping and injecting a liquid thermosetting resin under pressure. At this time, it is possible to use suction by connecting a vacuum pump or the like to the suction port. It is also possible to inject a liquid thermosetting resin composition by performing only suction. When an open mold is used, usually only suction is performed and a liquid thermosetting resin composition is injected. In order to achieve good impregnation by injection only by suction, a method using a resin diffusion medium as shown in US Pat. No. 4,902,215 is effective.

3. Heat-curing step After the reinforcing fiber base material is impregnated with a liquid thermosetting resin, thermosetting is performed in the mold. The curing conditions in the mold include a method in which the mold temperature at the time of pouring is maintained for a certain period of time, a method in which the temperature is raised to a temperature lower than the maximum curing temperature, a method in which the mold is retained for a certain period of time, and a temperature is increased to the maximum curing temperature. For example, a method of curing by holding for a certain time can be used. If the curing in the mold is short, the fiber-reinforced plastic can be efficiently produced. Therefore, the curing time in the mold is preferably 12 hours or less, and more preferably 6 hours or less.

  When cured at a temperature lower than the maximum curing temperature in the mold, after demolding, it can be held for a certain period of time in an oven or the like maintained at the maximum curing temperature and post-cured. When post-curing is performed, the time for maintaining the maximum curing temperature is preferably 4 hours or less, and more preferably 3 hours or less.

  In any case, the maximum curing temperature is preferably 160 to 210 ° C, and more preferably 170 to 190 ° C. Inexpensive materials can be used for the mold material, auxiliary material and heat source, so that the curing temperature in the mold is preferably 150 ° C. or lower, more preferably 130 ° C. or lower. For this reason, a method in which curing is performed at a temperature of 150 ° C. or less in the mold and post-curing is performed after demolding is preferably used.

  The prepreg of the present invention includes the following component [A], component [B] and component [C], and the component [B] has a flexural modulus of 2.0 to 5 at a temperature of 23 ° C. A crystalline polyamide having a water absorption of less than 1.2% after being immersed in water at a temperature of 23 ° C. and 0.0 GPa is included.

[A] Reinforcing fiber [B] Fiber or / and film [C] Matrix resin The prepreg of the present invention provides a fiber reinforced plastic in which the constituent elements [B] are distributed at high density between layers and the compression strength after impact is excellent. Therefore, the constituent element [B] is preferably distributed in the vicinity of one or both surface layers. Here, that the constituent element [B] is distributed in the vicinity of the surface layer means that 90% or more of the constituent element [B] exists in a region from the surface of the prepreg to 30% of the prepreg thickness.

  The evaluation of the distribution state of the component [B] in the prepreg can be performed as follows. First, the prepreg is put in close contact between two smooth support plates, and is cured by gradually raising the temperature over a long period of time. What is important at this time is to make the gel as low as possible. If the temperature is suddenly raised before gelation, the resin in the prepreg will flow, and therefore an accurate distribution state in the prepreg cannot be evaluated. After gelation, the temperature is gradually raised over a further time to cure the prepreg. The cured prepreg is cut, the cross section is enlarged 200 times or more, and a photograph of 200 mm × 200 mm or more is taken. When it is difficult to distinguish between the component [B] and the component [C], one of them is selectively stained and observed. As the microscope, a suitable one of an optical microscope or an electron microscope is used.

  First, an average prepreg thickness is obtained using this cross-sectional photograph. The average thickness of the prepreg is measured on at least 5 points on the photograph and the average is taken. Next, a line is drawn in parallel to the surface direction of the prepreg at a position 30% deeper than the thickness of the prepreg from the surface in contact with both support plates. The area of the component [B] existing between the surface in contact with the support plate and 30% of the parallel line is quantified on both sides of the prepreg, and the total area of the component [B] existing over the entire width of the prepreg. , And taking the ratio, the ratio of the component [B] existing within a depth of 30% from the surface of the prepreg is calculated. The area quantification can also be performed by a gravimetric method or image processing using an image analyzer. In order to eliminate the influence of partial distribution variation, this evaluation should be performed over the entire width of the obtained photo, and the same evaluation should be made for five or more arbitrarily selected photos, and the average must be taken. is there.

  The prepreg of the present invention can be produced by the following method.

  (Method 1) The component [A] is impregnated with the component [C], and the component [B] is arranged or bonded on both sides or one side to form a prepreg. At this time, if the component [B] is impregnated with the component [C] by heating and pressing, the component [C] is exposed on the outermost surface of the prepreg, and sufficient tackiness is obtained. When the component [B] is a textile structure in the form of a woven fabric, a knitted fabric or a nonwoven fabric, the component [C] may be impregnated in advance.

  (Method 2) By applying to a support such as a release paper, a component [C] is formed or placed on the surface of the component [C] formed into a film shape, and this and the component [A] is bonded and heated and pressed to form a prepreg. In this case, the constituent element [A] may be impregnated with the constituent element [C] in advance.

  (Method 3) After the constituent element [A], the constituent element [C] formed into a film shape, and the constituent element [B] are superposed, impregnation is performed by heating and pressing at the same time to form a prepreg. In this case, the positional relationship and temporal order in which the constituent element [A], the constituent element [B], and the constituent element [C] are superposed are arbitrary, but the constituent element [B] is the constituent element [A] and the constituent element [ Impregnation is facilitated when the positional relationship is such that it is sandwiched between C]. Also in this case, the component [A] may be impregnated with the component [C] in advance.

  When the form of the component [B] is a random arrangement, it is possible to take a method in which long fibers spun in advance are sprayed on the target, or long fibers discharged from the spinning machine are sprayed on the target. Furthermore, instead of spraying directly on the object, it is possible to take a method of collecting on a collecting body such as a wire net and then transferring it onto the object.

  Since the fiber reinforced plastic of the present invention is lightweight and has excellent mechanical properties such as strength and elastic modulus, the fiber volume content (Vf) of the fiber reinforced plastic may be in the range of 45 to 85%. More preferably, it is in the range of 50 to 85%.

  The fiber-reinforced plastic of the present invention is preferably used for aircraft, spacecraft fuselage, main wing, tail wing, moving blade, fairing, cowl and door, automobile platform, and the like.

  Hereinafter, the present invention will be described specifically by way of examples. The materials used in Examples and Comparative Examples are as follows.

1. Reinforcing fiber As the reinforcing fiber that is the constituent element [A] in the present invention, “Torayca” (registered trademark) T800S, which is a polyacrylonitrile (PAN) -based carbon fiber, 24,000 filaments (manufactured by Toray Industries, Inc.) was used. .

2. Reinforcing fiber fabric For the reinforcing fiber fabric, the above-mentioned PAN-based carbon fiber woven together with the following glass fiber and polyamide 66 fiber into a non-crimp structure was used.
Glass fiber: “ECE” 225 1/0, binder type DP (manufactured by Nitto Boseki Co., Ltd.)
Polyamide 66 fiber: 7 filaments, fineness 1.7 tex (manufactured by Toray Industries, Inc.)
The manufacturing method of the reinforced fiber fabric in a present Example is shown. FIG. 1 is a schematic perspective view of a reinforcing fiber fabric having a non-crimp structure of the present invention. As shown in FIG. 1, the PAN-based carbon fibers 1 are arranged in one direction at a density of 1.8 fibers / cm, and the glass fibers 2 are parallel to the PAN-based carbon fibers between the PAN-based carbon fibers. Arranged. Next, the polyamide 66 fibers 3 were arranged so as to be orthogonal to the PAN-based carbon fibers and crossed with the PAN-based carbon fibers 1 and the glass fibers 2.

3. Fiber made of crystalline polyamide (1) Non-woven fiber structure made of MX nylon Non-woven fiber structure made of MX nylon 6001 (MX (metaxylene type) nylon, manufactured by Mitsubishi Gas Chemical Co., Ltd.) It was produced by the method. The average fiber diameter was 8 μm, and the basis weight of the non-woven fiber structure was 7 g / m ² . The flexural modulus of MX nylon 6001 at a temperature of 23 ° C. was 4.5 GPa, the water absorption after 24 hours of immersion in water at a temperature of 23 ° C. was 0.3%, and the melting point was 243 ° C.

(2) Non-woven fiber structure made of polyamide 610 A non-woven fiber structure made of “Amilan” (registered trademark) CM2001 (polyamide 610, manufactured by Toray Industries, Inc.) was prepared by a melt blow method. The average fiber diameter was 8 μm, and the basis weight of the non-woven fiber structure was 7 g / m ² . “Amilan” (registered trademark) CM2001 has a flexural modulus of 2.2 GPa at a temperature of 23 ° C., a water absorption rate of 0.5% after 24 hours of immersion in water at a temperature of 23 ° C., and a melting point of 213 ° C.

(3) Non-woven fiber structure made of polyamide 12 A non-woven fiber structure made of “UBESTA” (registered trademark) 3014U (polyamide 12, manufactured by Ube Industries, Ltd.) was produced by a melt blow method. The average fiber diameter was 8 μm, and the basis weight of the non-woven fiber structure was 7 g / m ² . “UBESTA” (registered trademark) 3014U has a flexural modulus of 1.4 GPa at a temperature of 23 ° C., a water absorption rate of 0.3% after 24 hours of immersion in water at a temperature of 23 ° C., and a melting point of 178 ° C.

(4) Non-woven fiber structure made of polyamide 6 A non-woven fiber structure made of “Amilan” (registered trademark) CM1007 (polyamide 6, manufactured by Toray Industries, Inc.) was prepared by a melt blow method. The average fiber diameter was 8 μm, and the basis weight of the non-woven fiber structure was 7 g / m ² . “Amilan” (registered trademark) CM1007 has a flexural modulus of 2.6 GPa at a temperature of 23 ° C., a water absorption rate of 1.8% after immersion in water at a temperature of 23 ° C., and a melting point of 220%. ° C.

4). Film made of crystalline polyamide (1) Film made of MX nylon
A film made of MX nylon 6001 (MX nylon, manufactured by Mitsubishi Gas Chemical Co., Ltd.) was produced by the T-die method. The thickness of the film was 10 μm, and the basis weight of the film was 12 g / m ² .

(2) Film made of polyamide 12 A film made of “UBESTA” (registered trademark) 3014U (polyamide 12, manufactured by Ube Industries, Ltd.) was produced by the T-die method. The thickness of the film was 10 μm, and the basis weight was 10 g / m ² .

5). Adhesive Material A particulate adhesive material was prepared using the following raw materials.

"Sumika Excel" (registered trademark) 5003P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.)
"Epicoat" (registered trademark) 806 (Bisphenol F type epoxy resin, manufactured by Japan Epoxy Resins Co., Ltd.)
NC-3000 (biphenyl aralkyl type epoxy resin, manufactured by Nippon Kayaku Co., Ltd.)
"TEPIC" (registered trademark) -P (isocyanurate type epoxy resin, manufactured by Nissan Chemical Industries, Ltd.)
The manufacturing method of the adhesive material in a present Example is shown. “Epicoat” (registered trademark) 806 (23 wt%), NC-3000 (13 wt%), “TEPIC” (registered trademark) -P (4 wt%) were mixed at a temperature of 100 ° C. until uniform. An epoxy resin mixture was obtained. Next, “Sumika Excel” (registered trademark) 5003P (60% by weight) and an epoxy resin mixture (40% by weight) melted and kneaded with a twin-screw extruder to be compatible with each other were frozen and pulverized into particles. I made it. The resulting average particle diameter _{D 50} of the particles was 90 [mu] m (as measured by using a laser diffraction scattering method, Ltd. Seishin Enterprise Co. LMS-24.).

6). Matrix resin As the matrix resin of the present invention, the following matrix resin for RTM method and matrix resin for prepreg were used.

(1) RTM method matrix resin A RTM method matrix resin was prepared using the following raw materials.
"Araldite" (registered trademark) MY721 (tetraglycidyldiaminodiphenylmethane, manufactured by Vantico)
"Epicoat" (registered trademark) 630 (aminophenol type epoxy resin, manufactured by Japan Epoxy Resins Co., Ltd.)
"Epicoat" (registered trademark) 825 (bisphenol A type epoxy resin, manufactured by Japan Epoxy Resins Co., Ltd.)
・ GAN (Diglycidylaniline, Nippon Kayaku Co., Ltd.)
"Epicure" (registered trademark) W (diglycidyl aniline, manufactured by Japan Epoxy Resin Co., Ltd.)
・ "3,3'-DAS (3,3'-diaminodiphenylsulfone, manufactured by Mitsui Chemicals Fine Co., Ltd.)
"SumiCure" (registered trademark) S (4,4'-diaminodiphenylsulfone, manufactured by Sumitomo Chemical Co., Ltd.)
The manufacturing method of the matrix resin for RTM methods in a present Example is shown. "Araldite" (registered trademark) MY721 (40 wt%), "Epicoat" (registered trademark) 630 (10 wt%), "Epicoat" (registered trademark) 825 (35 wt%), GAN (15 wt%), The mixture was mixed until uniform at a temperature of 70 ° C. to obtain a main component of the matrix resin composition. In addition, “Epicure” (registered trademark) W (70 wt%), 3,3′-DAS (20 wt%), and “SumiCure” (registered trademark) S (10 wt%) were uniformly distributed at a temperature of 90 ° C. The resulting mixture was mixed to obtain a curing agent for the matrix resin composition. Next, 38% by weight of the curing agent was added to 100% by weight of the main agent, and mixed until uniform to obtain a matrix resin for RTM method.

(2) Matrix resin for prepreg A matrix resin for prepreg was produced using the following raw materials.
"Sumiepoxy" (registered trademark) ELM434 (tetraglycidyldiaminodiphenylmethane, manufactured by Sumitomo Chemical Co., Ltd.)
"Epicoat" (registered trademark) 825 (bisphenol A type epoxy resin, manufactured by Japan Epoxy Resins Co., Ltd.)
"Epiclon" (registered trademark) 830 (bisphenol F type epoxy resin, manufactured by Dainippon Ink & Chemicals, Inc.)
"SumiCure" (registered trademark) S (4,4'-diaminodiphenylsulfone, manufactured by Sumitomo Chemical Co., Ltd.)
"Sumika Excel" (registered trademark) 5003P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.)
The manufacturing method of the matrix resin for prepregs in a present Example is shown. "Sumiepoxy" (registered trademark) ELM434 (60% by weight), "Epicoat" (registered trademark) 825 (30% by weight), "Epicron" (registered trademark) 830 (10% by weight), "SumiCure" (registered trademark) S (45% by weight) and “Sumika Excel” (registered trademark) 5003P (16% by weight) were mixed well to obtain a matrix resin for prepreg.

  Moreover, the measuring method in an Example and a comparative example is shown below. The measurement results are shown in Tables 1 and 2 below.

1. Compressive strength after impact Based on SACMA SRM 2R-94, the compressive strength after impact was measured. A 5.4 kg weight was applied to the test piece, and a falling weight impact of 6.7 kJ / m was applied. Then, the compressive strength at 23 ° C. was measured by Instron 4201 (Instron).

2. 0 degree compressive strength in high temperature environment after water absorption Based on SACMA SRM 1R-94, the compressive strength in high temperature environment after water absorption was measured. After the test piece was immersed in warm water at a temperature of 70 ° C. for 14 days, the compressive strength at a temperature of 82 ° C. was measured with an Instron 4208 (manufactured by Instron).

(Example 1)
After the adhesive material was sprayed on the reinforcing fiber woven so that the weight per unit area was 27 g / m ² , the surface of the reinforcing fiber woven fabric was set to a temperature of 185 ° C. The adhesive was fixed on the reinforcing fiber fabric by passing it at 3 m / min. Next, the non-woven fabric structure of MX nylon was placed on the surface to which the adhesive material of the reinforcing fiber fabric was fixed, and fixed on the reinforcing fiber fabric with a press roller set at a temperature of 160 ° C. The obtained reinforcing fiber base material was excellent in handleability because a non-woven fiber structure composed of a reinforcing fiber fabric and MX nylon was integrated.

Next, using the obtained reinforcing fiber base material, a fiber reinforced plastic for measuring the compressive strength after impact was prepared. A reinforced fiber base material cut into 395 mm × 395 mm in a mold having a plate-like cavity of 400 mm × 400 mm × 4.8 mm, with the fiber direction of the PAN-based carbon fiber as 0 ° (45 ° / 0 ° / − (45 ° / 90 °) is repeated 3 times and 12 sheets are laminated, and (90 ° / -45 ° / 0 ° / 45 °) is repeated 3 times and 12 sheets are laminated and clamped. It was. Subsequently, after the mold is heated to a temperature of 60 ° C., a matrix resin for RTM method, which has been separately heated to a temperature of 60 ° C. in advance, is injected into the mold at an injection pressure of 0.2 MPa using a resin injection device. Then, the reinforcing fiber substrate was impregnated. After impregnation, the mold was heated to a temperature of 140 ° C. at a rate of 1.5 ° C./min, held at a temperature of 140 ° C. for 2 hours, then cooled to a temperature of 30 ° C. and demolded. After demolding, post-curing was performed in an oven under the following conditions to obtain a fiber reinforced plastic.
(1) The temperature is raised from 30 ° C. to 180 ° C. at a rate of 1.5 ° C./min.
(2) Hold at a temperature of 180 ° C. for 2 hours.
(3) The temperature is decreased from 180 ° C. to 30 ° C. at a rate of 2.5 ° C./min.

  Moreover, the fiber reinforced plastic for measuring the 0 degree compressive strength in the high temperature environment after water absorption was produced by the method similar to the above using the obtained reinforced fiber base material. However, a mold having a plate-like cavity of 400 mm × 400 mm × 1.2 mm was used. A reinforced fiber base material cut out to 395 mm × 395 mm was set by laminating six reinforcing fiber base materials in the 0 ° direction with the fiber direction of the PAN-based carbon fiber being 0 °.

  All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 53%, which was sufficiently high.

  The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 260 GPa, and the 0 ° compressive strength in a high temperature environment after water absorption. Was 1010 GPa, which was found to be sufficiently high.

(Example 2)
A reinforcing fiber substrate of the present invention was produced in the same manner as in Example 1 using a nonwoven fabric-like fiber structure made of polyamide 610. The obtained reinforcing fiber base material was excellent in handleability because a nonwoven fiber structure composed of reinforcing fiber fabric and polyamide 610 was integrated.

  Using the obtained reinforcing fiber base material, a fiber-reinforced plastic for measuring the compressive strength after impact and the 0 ° compressive strength in a high-temperature environment after water absorption was produced in the same manner as in Example 1. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 53%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 270 GPa, and the 0 ° compressive strength in a high temperature environment after water absorption. Was 960 GPa, both of which were found to be sufficiently high.

(Comparative Example 1)
A fiber reinforced plastic not containing the component [B] was produced, and the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption were measured. Using a reinforced fiber fabric having a non-crimp structure, a fiber reinforced plastic for measuring compressive strength after impact and 0 ° compressive strength in a high temperature environment after water absorption was prepared in the same manner as in Example 1. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 53%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The 0 ° compressive strength in a high temperature environment after water absorption was 1,000 GPa and sufficiently high. However, it was found that the compressive strength after impact was 130 GPa, which was insufficient.

(Comparative Example 2)
A reinforcing fiber substrate of the present invention was produced in the same manner as in Example 1 using a nonwoven fabric-like fiber structure made of polyamide 12. The obtained reinforced fiber base material was excellent in handleability because the non-woven fiber structure composed of the reinforced fiber fabric and polyamide 12 was integrated.

  Using the obtained reinforcing fiber base material, a fiber-reinforced plastic for measuring the compressive strength after impact and the 0 ° compressive strength in a high-temperature environment after water absorption was produced in the same manner as in Example 1. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 53%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength under high temperature environment after water absorption. The compressive strength after impact was 280 GPa, which is sufficiently high. The 0 ° compressive strength was 790 GPa, which was found to be insufficient.

(Comparative Example 3)
A reinforced fiber base material of the present invention was produced in the same manner as in Example 1 using a nonwoven fabric-like fiber structure made of polyamide 6. The obtained reinforced fiber base material was excellent in handleability because the non-woven fiber structure composed of the reinforced fiber fabric and polyamide 6 was integrated.

  Using the obtained reinforcing fiber base material, a fiber-reinforced plastic for measuring the compressive strength after impact and the 0 ° compressive strength in a high-temperature environment after water absorption was produced in the same manner as in Example 1. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 53%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 270 GPa, which is sufficiently high, but in a high temperature environment after water absorption. The 0 ° compressive strength was 880 GPa, which was found to be insufficient.

(Example 3)
A prepreg matrix resin for prepreg was impregnated into reinforcing fibers arranged in one direction by a drum winding method to prepare a prepreg. The reinforcing fiber per unit area was 190 g / m ² , and the matrix resin amount was 92 g / m ² . Next, a non-woven fiber structure made of MX nylon was placed on the prepreg and fixed by pressing with a calender roll. The obtained prepreg was easy to handle.

Using the obtained prepreg, first, a fiber reinforced plastic for measuring the compressive strength after impact was prepared. The PAN-based carbon fiber has a fiber direction of 0 °, and (45 ° / 0 ° / −45 ° / 90 °) is repeated three times and 12 sheets are laminated, and then (90 ° / −45 ° / 0 ° / 45 After repeating 12 times, 12 layers were set, and after bugging, curing was performed under the following conditions while applying pressure to 0.6 MPa in an autoclave to obtain a fiber reinforced plastic.
(1) The temperature is raised from 30 ° C. to 180 ° C. at a rate of 1.5 ° C./min.
(2) Hold at a temperature of 180 ° C. for 2 hours.
(3) Decreasing the temperature from 180 ° C. to 30 ° C. at a rate of 2.5 ° C./min. Next, a fiber reinforced plastic for measuring 0 ° compressive strength in a high temperature environment after water absorption is the same as above. It was produced by the method. However, the fiber direction of the PAN-based carbon fiber was set to 0 °, and a laminate of 6 reinforcing fiber base materials in the 0 ° direction was set.

  All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. Further, the fiber volume content (Vf) of the reinforcing fibers was 56%, which was sufficiently high.

  The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 300 GPa, and the 0 ° compressive strength in a high temperature environment after water absorption. Was 1120 GPa, all of which were found to be sufficiently high.

Example 4
A prepreg was produced in the same manner as in Example 3 using a non-woven fiber structure of polyamide 610. The obtained prepreg was easy to handle. Next, a fiber reinforced plastic was produced in the same manner as in Example 3. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. Further, the fiber volume content (Vf) of the reinforcing fibers was 56%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 300 GPa, and the compressive strength in a high temperature environment after water absorption was 1080 GPa. It was found that both were sufficiently high.

(Example 5)
A prepreg was produced in the same manner as in Example 3 using an MX nylon film. The obtained prepreg was easy to handle. Next, a fiber reinforced plastic was produced in the same manner as in Example 3. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 55%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 320 GPa, and the 0 ° compressive strength in a high temperature environment after water absorption. Was 1120 GPa, all of which were found to be sufficiently high.

(Comparative Example 4)
A prepreg was produced in the same manner as in Example 3 using a nonwoven fabric-like fiber structure of polyamide 12. The obtained prepreg was easy to handle. Next, a fiber reinforced plastic was produced in the same manner as in Example 3. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. Further, the fiber volume content (Vf) of the reinforcing fibers was 56%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 320 GPa, which is sufficiently high. The 0 ° compressive strength was 870 GPa and was found to be insufficient.

(Comparative Example 5)
A prepreg was produced in the same manner as in Example 3 using a polyamide 6 nonwoven fiber structure. The obtained prepreg was easy to handle. Next, a fiber reinforced plastic was produced in the same manner as in Example 3. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. Further, the fiber volume content (Vf) of the reinforcing fibers was 56%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 310 GPa, which is sufficiently high. The 0 ° compressive strength was 920 GPa, which was found to be insufficient.

(Comparative Example 6)
Using a polyamide 12 film, a prepreg was produced in the same manner as in Example 3. The obtained prepreg was easy to handle. Next, a fiber reinforced plastic was produced in the same manner as in Example 3. All of the obtained fiber reinforced plastics had no unimpregnated part and had good quality. The fiber volume content (Vf) of the reinforcing fiber was 55%, which was sufficiently high. The obtained fiber reinforced plastic was used to measure the compressive strength after impact and the 0 ° compressive strength in a high temperature environment after water absorption. The compressive strength after impact was 360 GPa, which is sufficiently high, but in a high temperature environment after water absorption. The 0 ° compressive strength was 820 GPa, which was found to be insufficient.

  The fiber-reinforced plastic of the present invention can be preferably used for aircraft, spacecraft fuselage, main wing, tail wing, moving wing, fairing, cowl and door, automobile platform, and the like.

FIG. 1 is a schematic perspective view of a reinforcing fiber fabric having a non-crimp structure of the present invention.

Explanation of symbols

1: PAN-based carbon fiber 2: Glass fiber 3: Polyamide 66 fiber

Claims (14)

In the reinforcing fiber substrate including the following component [A] and component [B], the component [B] has a flexural modulus of 2.0 to 5.0 GPa at a temperature of 23 ° C., and A reinforced fiber base material comprising a crystalline polyamide having a water absorption rate of less than 1.2% after 24 hours of immersion in water at a temperature of 23 ° C.
[A] Reinforcing fiber [B] Fiber or / and film   The reinforcing fiber substrate according to claim 1, wherein the constituent element [B] includes a crystalline polyamide having an aromatic ring.   The reinforcing fiber substrate according to claim 1 or 2, wherein the constituent element [B] contains a crystalline polyamide having a melting point within a temperature range of 200 to 350 ° C. The reinforcing fiber substrate according to any one of claims 1 to 3, wherein the constituent element [B] contains a crystalline polyamide represented by the following general formula (I).

(Wherein, m is an integer from 1 to 12, and n is an integer)   The reinforcing fiber substrate according to any one of claims 1 to 4, wherein the constituent element [B] is distributed on one or both surfaces.   The reinforcing fiber substrate according to any one of claims 1 to 5, wherein the constituent element [B] is a fiber structure in a woven, knitted or non-woven shape.   A fiber reinforced plastic comprising: a reinforcing fiber substrate according to any one of claims 1 to 6 disposed in a mold, impregnated with a liquid thermosetting resin composition, and then cured by heating. Production method. In the prepreg including the following component [A], component [B] and component [C], the component [B] has a flexural modulus of 2.0 to 5.0 GPa at a temperature of 23 ° C. A prepreg comprising a crystalline polyamide having a water absorption of less than 1.2% after 24 hours of immersion in water at a temperature of 23 ° C.
[A] Reinforcing fiber [B] Fiber or / and film [C] Matrix resin   The prepreg according to claim 8, wherein the constituent element [B] contains a crystalline polyamide having an aromatic ring.   The prepreg according to claim 8 or 9, wherein the constituent element [B] includes a crystalline polyamide having a melting point within a temperature range of 200 to 350 ° C. The prepreg according to any one of claims 8 to 10, wherein the constituent element [B] contains a crystalline polyamide represented by the following general formula (I).

(Wherein, m is an integer from 1 to 12, and n is an integer)   The prepreg according to any one of claims 8 to 11, wherein the component [B] is distributed in the vicinity of one or both surface layers.   The prepreg according to any one of claims 8 to 12, wherein the constituent element [B] is a fiber structure in the form of a woven fabric, a knitted fabric or a non-woven fabric. In the fiber reinforced plastic including the following constituent element [A], constituent element [B] and constituent element [D], the constituent element [B] has a flexural modulus of 2.0-5. A fiber-reinforced plastic comprising crystalline polyamide having a water absorption rate of less than 1.2% after immersion in water at 23 ° C. for 0 GPa.
[A] Reinforcing fiber [B] Fiber or / and film [D] Cured product of matrix resin

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