JP2008056795A - Prepreg and fiber reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg for a fiber reinforced composite material having high flame resistance and high heat resistance with containing no flame retardant such as a halogen and phosphorus, etc., and excellent in fast curing and operational stability, as well as to provide the fiber reinforced composite material obtained from it. <P>SOLUTION: This prepreg for the composite material comprises a thermosetting resin composition comprising a following component [A] and a component [B], and a following component [C], in which the prepreg contains the component [B] of 4-20 pts.wt. based on the component [A] of 100 pts.wt., and a gelling time of the prepreg at 150°C is ≤5 minutes. The component [A] is a benzoxazine resin with a unit structure represented by a specific structural formula, the component [B] is an acid catalyst, and the component [C] is a flame retardant reinforced fiber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a prepreg for obtaining a fiber-reinforced composite material suitable for aircraft use, marine use, sports use, and other general industrial uses, and a fiber-reinforced composite material obtained therefrom.

  Thermosetting resins such as epoxy resins and phenolic resins, paints, electrical / electronic materials, adhesives, fiber reinforced composite materials, due to their excellent mechanical properties, electrical properties, heat resistance, chemical resistance, etc. It is used for the matrix resin.

  Fiber reinforced composite materials that use thermosetting resins as matrix resins, especially carbon fiber reinforced composite materials that use carbon fibers, have excellent mechanical properties, so they can be used in sports equipment such as golf clubs, tennis rackets, and fishing rods. It is used in a wide range of fields, such as structural materials for aircraft and vehicles, and reinforcement of concrete structures. Recently, carbon fiber reinforced composite materials have excellent electromagnetic shielding properties and excellent mechanical properties due to the electrical conductivity of carbon fibers, so that the housings of electrical and electronic equipment such as laptop computers and video cameras can be used. It is also used for the body, etc., which helps to reduce the thickness of the housing and reduce the weight of the equipment. Such fiber-reinforced composite materials are often obtained by laminating prepregs obtained by impregnating reinforcing fibers with thermosetting resins.

  Among them, especially in structural materials and building materials such as aircraft and vehicles, it is extremely dangerous that the structural materials are ignited and burned by fire and toxic gas is generated, so the material has flame retardancy. There is a strong demand for that.

  Also, in electrical and electronic equipment applications, it is required to make the material flame-retardant in order to prevent accidents in which the casing and parts are ignited and burned by being exposed to heat generated from the inside of the apparatus or external high temperature. However, many of the conventionally known thermosetting resins do not have sufficient flame retardancy, and various flame retardants are added.

  For example, brominated flame retardants known as typical halogenated flame retardants are widely used because they have an excellent flame retardant effect, but generate harmful substances such as hydrogen bromide during combustion, Its use is being restricted because it can adversely affect the human body and the natural environment.

  Therefore, the use of phosphorus-based flame retardants, nitrogen-based flame retardants, inorganic flame retardants, and the like as alternative flame retardants has been studied. Generally, these flame retardants are compared to halogen-based flame retardants. Since the flame retardant effect is inferior, it is necessary to use a large amount or a combination of these flame retardants. As a result, there has been a problem that properties other than flame retardancy are impaired, such as a significant decrease in heat resistance and elastic modulus of the composite material.

  Under such circumstances, the use of a benzoxazine resin, which has a higher aromatic ring content than a conventional thermosetting resin and is relatively excellent in flame retardancy, has been studied.

Although the cured product of dihydrobenzoxazine resin using ring-opening polymerization is excellent in flame retardancy, heat resistance, mechanical properties, electrical properties, etc., compared to thermosetting resins such as epoxy resins and phenolic resins, The curing temperature is usually as high as 200 ° C. or higher, and the curing rate is slow, so that the productivity is poor (see, for example, Patent Document 1).
In response to this problem, the curability can be improved somewhat by adding a novolak type phenol resin to a compound having a dihydrobenzoxazine ring (see, for example, Patent Document 2). A technique is disclosed in which curability is superior to those added individually by mixing an initiator simultaneously (see, for example, Patent Document 3). However, when a general novolac type phenol resin is added to the reaction system, the curing rate can be increased, but there is a disadvantage that the heat resistance is lowered. In addition, the viscosity of the matrix resin composition is increased, and since the prepreg manufacturing process, in particular, it cannot be applied at the time of resin film production, if it is softened at a higher temperature than usual, a curing reaction proceeds during molding, and the viscosity of the resin changes with time, There exists a problem that the thickness of a film cannot be controlled and the target prepreg cannot be obtained. Furthermore, since the curing reaction proceeds even at a low temperature below the prepreg molding temperature, Tg increases when the prepreg is cut and laminated, the surface of the prepreg becomes hard, and the tackiness and drape properties of the prepreg decrease. There is a problem.
JP 49-47387 Japanese Patent Laid-Open No. 9-272786 JP 2002-128987 A

  The present invention solves the above-mentioned problems in the prior art, and has a high flame retardancy and heat resistance, and has a high curing speed and excellent work stability without including a flame retardant such as halogen or phosphorus. An object of the present invention is to provide a prepreg that provides a fiber and a fiber-reinforced composite material obtained therefrom.

  In order to achieve the above object, the prepreg of the present invention has the following configuration. That is, a prepreg for a composite material comprising a thermosetting resin composition containing the following [A] component and [B] component, and the following [C] component, wherein A composite material prepreg comprising 4 to 20 parts by weight of the component [B] and having a gel time at 150 ° C. of 5 minutes or less.

  [A] Benzoxazine resin having a unit structure represented by the following structural formula (I) or (II)

(In the formula, R ₁ represents a chain alkyl group having 1 to 12 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, a phenyl group, or a chain alkyl group having 1 to 12 carbon atoms, or phenyl substituted with halogen. A hydrogen atom bonded to at least one of the ortho and para carbon atoms to which the oxygen atom of the aromatic ring is bonded)

(Wherein R ₂ represents any one of a hydrogen atom, a chain alkyl group having 1 to 12 carbon atoms, and a halogen, and each R ₂ may be the same as or different from each other. X is — CH ₂ -,
A group represented by —C (CH ₃ ) ₂ —, —CH (CH ₃ ) —, —S—, —SO ₂ —, —CO—, —O—, or a structure having no X is selected. Is one)
[B] Acid Catalyst [C] Flame Retardant Reinforcing Fiber The composite material of the present invention has the following configuration in order to achieve the above object. That is, it is a fiber-reinforced composite material obtained by curing the above-mentioned composite material prepreg.

  According to the present invention, as described below, while satisfying various properties required for composite material prepregs and composite materials, it is excellent in flame retardancy without adding a flame retardant such as halogen, phosphorus and the curing rate. It is possible to provide a prepreg for a composite material and a composite material having a high speed.

  The prepreg for a composite material of the present invention is composed of a thermosetting resin composition and a flame retardant reinforcing fiber which is a [C] component, and the thermosetting resin composition has the structural formula (I) or It comprises a [A] component that is a benzoxazine resin having a structural unit represented by (II) and a [B] component that is an acid catalyst. The thermosetting resin composition is preferably at least partially impregnated with the flame-retardant reinforcing fiber which is the [C] component.

Specific examples of R ₁ in the structural formula (I) include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, cyclopentyl group, cyclohexyl group, phenyl group, o-methylphenyl group, m-methylphenyl group, p-methylphenyl group, o-ethylphenyl group, m-ethylphenyl group, p-ethylphenyl group, ot-butylphenyl group, mt-butylphenyl Preferred examples include a group, pt-butylphenyl group, o-chlorophenyl group, o-bromophenyl group and the like. Among these, a methyl group, an ethyl group, a propyl group, a phenyl group, and an o-methylphenyl group are more preferable because they give good handleability.

  In the present invention, the component [A] is preferably selected from the group consisting of resins represented by the following structural formulas (III) to (XIII) because good handleability and curability are obtained. Used.

  The benzoxazine resin as the component [A] may be a monomer, may be polymerized in several molecules, or may be used simultaneously with benzoxazine resins having different structures. By using benzoxazine resins having different structures at the same time, crystallization of the benzoxazine resin is suppressed and the viscosity of the resin composition is reduced compared to the case of using only a single compound, and handling at a lower temperature is easier. There is a case.

  In the present invention, in addition to the benzoxazine resin, the thermosetting resin composition includes thermosetting resins such as epoxy resins and cyanate ester resins, and thermosetting resins such as epoxy resins and cyanate ester resins. A curing agent for the conductive resin may be included.

  The thermosetting resin composition should not contain a phenol resin having no benzoxazine ring in the molecule. Specifically, in the thermosetting resin composition, the benzoxazine ring in the molecule The content of the phenolic resin not having a component is 5 parts by weight or less, preferably 3 parts by weight or less, more preferably 2.5 parts by weight or less, and even more preferably 2 parts by weight or less with respect to 100 parts by weight of the component [A]. Most preferably, it is 0 parts by weight. If the content of the phenolic resin having no benzoxazine ring is too high, the viscosity of the thermosetting resin composition that becomes the matrix resin may increase, and problems may occur in the prepreg manufacturing process. When prepreg is manufactured with, the resin cannot be applied at the time of resin film production, and if it is softened at a higher temperature than usual at the time of film formation, the curing reaction proceeds during molding, and the viscosity of the resin changes with time, and the film thickness is controlled. In some cases, the target prepreg cannot be obtained. Further, since the curing reaction proceeds even at a low temperature below the prepreg molding temperature, the glass transition temperature (hereinafter sometimes abbreviated as Tg) of the thermosetting resin composition when the prepreg is cut and laminated. Since the surface of the prepreg tends to harden due to the rise, the tackiness and drape of the prepreg may be reduced, and the heat resistance and interlaminar shear strength (hereinafter referred to as ILSS) of the composite material obtained by curing the prepreg may be reduced. May decrease. The phenolic resin having no benzoxazine ring here is generally a phenolic monomer and an aldehyde that are subjected to an addition reaction in the presence of an alkali or acid catalyst to increase the molecular weight. There are phenol resins such as novolac type phenol resin and resol type phenol resin.

  [B] component in this invention is an acid catalyst, has the effect | action which accelerates | stimulates the ring-opening reaction of a benzoxazine resin, and is indispensable in order to achieve the gel time of 5 minutes or less at 150 degreeC. Specific examples of the component [B] include mononuclear phenol compounds such as carboxylic acid, sulfonic acid, catechol, hydroquinone, resorcinol, pyrogallol, naphthol derivatives, hydroxyanthracene derivatives, hydroxyanthraquinone derivatives, Lewis acids, and the like. it can.

  Among these, a Lewis acid is preferably used as the component [B]. The Lewis acid has strong nucleophilicity to the lone pair of oxygen atoms of the benzoxazine ring, and has the effect of improving the curability of the benzoxazine resin.

  Examples of Lewis acids include boron trihalide complexes. Of these, boron trichloride complexes such as boron trichloride amine complex and boron trichloride dimethyl sulfur complex are preferably used from the viewpoint of curability, and boron trichloride amine complex is particularly preferable.

  In addition, as the component [B], compounds such as acid anhydrides and sulfonic acid esters that do not have protons but generate protons by hydrolysis or the like can also be used. As such a compound, a toluenesulfonic acid derivative is preferably used since both curability and storage stability are achieved. Since the sulfonic acid obtained from the toluenesulfonic acid derivative has high acidity, the proton donating property is high, and the hydroxyl group generated by the ring opening of the benzoxazine ring is stabilized, so that the effect of improving curability is great.

  Among the toluenesulfonic acid derivatives, p-toluenesulfonic acid ester is preferably used because it has a great effect of improving curability. Examples of p-toluenesulfonic acid esters include methyl p-toluenesulfonate, ethyl p-toluenesulfonate, n-propyl p-toluenesulfonate, isopropyl p-toluenesulfonate, n-butyl p-toluenesulfonate, Examples include 2-butynyl p-toluenesulfonate, 3-butynyl p-toluenesulfonate, isobutyl p-toluenesulfonate, and the like. In particular, methyl p-toluenesulfonate and ethyl p-toluenesulfonate are more preferred in the present invention. Preferably used.

  In addition, since p-toluenesulfonic acid ester has a higher polymerization initiation temperature for the benzoxazine ring as the molecular weight of the substituent of the ester increases, an appropriate catalyst can be selected depending on the intended polymerization initiation temperature. is there. These acid catalysts may be used alone or in combination of two or more.

  It is preferable that the compounding quantity of this [B] component shall be 4-20 weight part with respect to 100 weight part of [A] component. Furthermore, it is preferable that it is 5-18 weight part, and it is especially preferable that it is 7-15 weight part. If the amount of the component [B] is too small, the effect of promoting the ring opening of the benzoxazine ring may be insufficient. If the amount of the component [B] is too large, a large amount of the component remains in the resin composition. Mechanical properties and flame retardancy may be reduced.

The thermosetting resin composition used in the prepreg of the present invention must be cured in a short time for industrial material applications that are desired to be able to be produced in large quantities in a short time, especially for applications such as housings for electrical and electronic equipment. Specifically, the gel time at 150 ° C. needs to be 5 minutes or less. Further, for the purpose of improving productivity, it is desirable to gel in a shorter time. In addition, the gel time in 150 degreeC of a thermosetting resin composition can be measured as follows. That is, the thermosetting resin composition is sampled as a 2 cm ³ sample, put into a die heated to 150 ° C. using a curastometer, and a torsional stress is applied to the die to increase the viscosity as the sample cures. Measured as transmitted torque. The time until the torque reached 0.001 N · m after the start of measurement was defined as the gel time at 150 ° C.

  In the present invention, the thermosetting resin composition is obtained by mixing the above-described components. Although it does not specifically limit as a mixing method, A kneader, a planetary mixer, a 3 roll, a twin screw extruder, etc. are used preferably.

  [C] component in this invention is a reinforced fiber which has a flame retardance. Examples of reinforcing fibers having flame retardancy include metal fibers such as aluminum and stainless steel, polyacrylonitrile-based, rayon-based, pitch-based carbon fibers, graphite fibers, insulating fibers such as glass, boron fibers, boron carbide fibers, Mention may be made of reinforcing fibers such as phenol fibers. Among these, it is preferable to use carbon fiber in order to exhibit excellent flame retardancy, specific elastic modulus, and specific strength in the fiber-reinforced composite material. Also, two or more of these fibers may be mixed and used.

  When carbon fiber is used as the component [C], any type of carbon fiber can be used depending on the application, and carbon fiber having a normal tensile strength of 1.0 GPa to 9.0 GPa can be used. In view of high tensile strength inherent to the fiber and impact resistance when a composite material is used, the tensile strength is preferably as high as possible, and more preferably 2.0 GPa to 9.0 GPa. In addition, as the carbon fiber to be used, those whose tensile elastic modulus is usually 50 Gpa to 1000 GPa can be used. However, using a carbon fiber having a high tensile elastic modulus provides a high elastic modulus when a composite material is used. It leads to. Further, such a tensile elastic modulus is required to have high rigidity, and more preferably 150 GPa to 1000 GPa, when importance is attached to thinning and lightening such as a housing of an electric / electronic device. The tensile strength and elastic modulus of carbon fiber here mean the strand tensile strength and strand tensile elastic modulus measured according to JIS R7601 (1986).

  Moreover, when using carbon fiber as a [C] component, it is preferable that the cross-sectional shape of the single fiber of carbon fiber is substantially perfect circle shape. Here, the fact that the cross-sectional shape of the single fiber is substantially a perfect circle means that the ratio R / r between the radius R of the circle circumscribing the cross-sectional shape of the single fiber and the radius r of the inscribed circle is 1.0 to 1. .1, preferably in the range of 1.0 to 1.05. When the cross-sectional shape of a single fiber is a perfect circle, the surface area of the carbon fiber is smaller and the contact area with the resin is smaller than when it is not a perfect circle. Becomes slower and flame retardancy is further improved. In addition, when the cross-sectional shape of the single fiber is a perfect circle, during prepreg molding, process surfaces such as a decrease in strength due to single yarn breakage due to rubbing between single yarns or bundles of carbon fibers, generation of fuzz, and yarn breakage Trouble is difficult to occur. Examples of the carbon fiber having a perfect circular cross section include “Torayca (registered trademark)” T700S and “Torayca (registered trademark)” M30S manufactured by Toray Industries, Inc.

The fiber-reinforced composite material prepreg of the present invention preferably has a fiber content mass (hereinafter referred to as Wf) of 50 to 90% with respect to the total mass of the fiber-reinforced composite material prepreg, and more preferably 60 to
It is preferably 85%, more preferably 70 to 85%. If the Wf is too small, the effect of improving the flame retardancy is not sufficient, and the various properties required for the fiber-reinforced composite material may not be satisfied. Moreover, when this Wf is too large, the adhesiveness between the reinforcing fiber and the matrix resin is lowered, and when the prepregs are laminated, the prepregs do not adhere to each other, and the resulting composite material may peel off between the layers. Wf here means the fiber mass content measured according to JIS K7071 (1988).

  Examples of the form of the reinforcing fiber include, but are not limited to, a long fiber aligned in one direction, a bi-directional woven fabric, a multiaxial woven fabric, a non-woven fabric, a mat, a knit, and a braid. The long fiber here means a single fiber or a fiber bundle substantially continuous for 10 mm or more.

  A so-called unidirectional prepreg using long fibers aligned in one direction is particularly preferable because the directions of the reinforcing fibers are aligned, and the bending rate of the fibers is small, so that the strength utilization factor in the fiber direction is high. Further, the unidirectional prepreg is particularly preferable when a plurality of prepregs are laminated after being laminated in an appropriate laminated configuration because the elastic modulus and strength of each surface of the fiber-reinforced composite material can be freely controlled.

  Further, a fabric prepreg using various fabrics is also preferable because a material having low strength and elastic anisotropy can be obtained, and a pattern of a fiber fabric is floated on the surface and is excellent in design. It is also possible to form composite materials using multiple types of prepregs, for example both unidirectional and woven prepregs.

  Next, a method suitable for obtaining the composite material prepreg of the present invention will be described. The composite material prepreg of the present invention is not particularly limited as long as the above-described thermosetting resin composition is impregnated into the reinforcing fiber. For example, the thermosetting resin composition is dissolved in a solvent such as methyl ethyl ketone or methanol. By a wet method in which the viscosity is lowered and impregnated into the reinforcing fiber, or a hot melt method in which the thermosetting resin composition is reduced in viscosity by heating and impregnated into the reinforcing fiber substantially without using a solvent. Can be manufactured.

  In the wet method, a prepreg can be obtained by immersing reinforcing fibers in a liquid containing a matrix resin, and then pulling up and evaporating the solvent using an oven or the like.

  In the hot melt method, a method of directly impregnating a reinforcing fiber with a thermosetting resin composition whose viscosity has been reduced by heating, or a resin film in which the resin composition is once coated on release paper or the like is first produced and then reinforced. A prepreg can be manufactured by impregnating a reinforcing fiber with a thermosetting resin composition by overlapping the resin film from both sides or one side of the fiber and applying heat and pressure. In the hot melt method, since there is substantially no solvent remaining in the prepreg, it is more preferably used in the present invention.

  Moreover, in order to make the handleability of a prepreg into an appropriate range, in the process of impregnating the reinforcing fiber with the thermosetting resin composition, the maximum temperature reached by the thermosetting resin composition is 60 ° C to 150 ° C. It is good that it is the range, More preferably, it is the range of 80 to 130 degreeC. If the maximum temperature is too high, the curing reaction may partially proceed in the thermosetting resin composition, and the Tg of the uncured resin may increase, so that appropriate draping properties may not be achieved in the resulting prepreg. Moreover, when the maximum temperature is too low, it may be difficult to sufficiently impregnate the reinforcing fibers.

  The prepreg of the present invention does not necessarily need to be impregnated with the thermosetting resin composition to the inside of the fiber bundle, and the thermosetting resin composition is near the surface of the fiber or fiber woven fabric arranged in one direction in a sheet shape. May be a mode in which is localized.

  In order to form a fiber-reinforced composite material using the prepreg of the present invention, a method of heat-curing the thermosetting resin composition while applying pressure to the laminate after laminating the prepreg can be used.

  Examples of methods for heat-curing the thermosetting resin composition while applying pressure include a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, and an internal pressure molding method.

  The temperature at which the fiber-reinforced composite material is molded depends on the type of curing agent contained in the thermosetting resin composition, but is usually preferably 80 to 220 ° C. If the molding temperature is too low, sufficient fast curability may not be obtained. Conversely, if the molding temperature is too high, warping due to thermal strain may be likely to occur.

  The fiber-reinforced composite material obtained by the present invention has a flame retardancy measured at a thickness of 2 mm or less, and has a high flame retardancy of V-1 or more, preferably V-0 as measured by UL94 standard. It becomes. In addition, when used as a casing of an electric / electronic device, assuming a possibility of being used with a thinner wall thickness, the thickness is 1.5 mm or less and the flame retardancy is V-1 or more, preferably Is difficult even if it has a high flame retardancy of V-0 or a thinner wall thickness of 1.2 mm or less, 0.8 mm or less, and even 0.5 mm or less. The flame retardancy is V-1 or higher, and in particular, V-0 has high flame retardancy.

  Here, the flame retardancy of V-0 and V-1 is the combustion time and its state, the presence or absence of fire spread, the presence or absence of dripping (drip) in the UL94 standard (American Combustion Test Method devised by Underwriters Laboratories Inc.) And flame retardancy satisfying the conditions of V-0 and V-1 defined by the flammability of the droplets and the drops.

  Hereinafter, the present invention will be described more specifically with reference to examples. In this example, various characteristics were measured by the following methods.

(1) Gel time of thermosetting resin composition 2 cm ³ was prepared from the thermosetting resin composition as a sample, and a curastometer V type (manufactured by Nigo Shoji Co., Ltd.) was used to track the curing of the resin. The gel time was measured. The time when the torque reached 0.001 N · m after the start of measurement was defined as the gel time.

(2) Glass transition temperature (Tg)
A sample having a mass of 15 mg was cut from the fiber-reinforced composite material to prepare a sample, and measured using a differential scanning calorimeter (DSC) according to the method described in JIS K7121 (1987). The heating rate was 40 ° C./min, and the midpoint glass transition temperature of the portion where the DSC curve showed a step-like change was Tg. In this example, Pyris DSC (manufactured by Perkin Elmer Instruments) was used as a differential scanning calorimeter.

(3) Flame retardance Flame retardancy was evaluated by a vertical combustion test based on the UL94 standard. Five test pieces having a width of 12.7 ± 0.1 mm and a length of 127 ± 1 mm were cut out from the molded fiber-reinforced composite material. The height of the flame of the burner was adjusted to 19 mm, and the lower end of the center of the test piece held vertically was exposed to the flame for 10 seconds, then separated from the flame and the burning time was recorded. Immediately after extinguishing the flame, the burner flame was further applied for 10 seconds to separate it from the flame, and the combustion time was measured. If there is no flammable drop (drip) and the time until extinction is within 10 seconds in both the first and second times, and the total burning time after 10 flames contacted 5 times is within 50 seconds, V It was determined as V-1 if the combustion time was within 30 seconds and the total combustion time after contacting the five test pieces 10 times within 250 seconds. Moreover, it was determined as V-2 when there was a flammable drop even in the same combustion time as V-1, and as V-out when the combustion time was longer than that or when the test piece was burned up to the test piece holder.

(4) Life of prepreg The prepreg was evaluated in accordance with the following judgment criteria in a 23 ° C. environment by comparing Tg changes at the start of measurement and 45 days. Tg was measured by the same method as in (2) above.
◯: Tg increase is smaller than 10 ° C., prepreg life is long and stability is good.
(Triangle | delta): Tg raise is 10-15 degreeC, and the life of a prepreg is a little short.
X: Tg increase is larger than 15 ° C., and the life of the prepreg is short.
XX: Tg increase is larger than 30 ° C., curing is progressing, and the prepregs are not bonded to each other when the prepregs are laminated.
(5) Interlaminar shear strength (ILSS) of composite material
A sample was prepared by cutting a test piece having a width of 10.0 ± 0.2 mm, a thickness of 3.0 ± 0.2 mm, and a length of 21.0 ± 1 mm from the fiber reinforced composite material, and described in JIS K7078 (1991). ILSS was determined according to the method. The ILSS was measured for five samples and the average intensity was determined. The measurement was performed in a room temperature dry state (23 ° C., relative humidity 50%).

The materials shown below were kneaded with a kneader according to the compositions shown in Table 1 and Table 2 to prepare resin compositions used in each Example and each Comparative Example.
[A] component Fa type benzoxazine resin having the following structure (manufactured by Shikoku Kasei Kogyo Co., Ltd.)

  Pd-type benzoxazine resin having the following structure (manufactured by Shikoku Kasei Kogyo Co., Ltd.)

  Bis-S type benzoxazine resin having the following structure (manufactured by Konishi Chemical Industry Co., Ltd.)

[B] component DY9577 (boron trichloride octylamine complex, manufactured by Huntsman Advanced Materials Co., Ltd.)
p-Toluenesulfonic acid methyl ester (manufactured by Tokyo Chemical Industry Co., Ltd.)
p-Toluenesulfonic acid ethyl ester (manufactured by Tokyo Chemical Industry Co., Ltd.)
Other components “Phenolite” (registered trademark) TD2131 (Novolak type phenolic resin, melting point 80 ° C., manufactured by Dainippon Ink & Chemicals, Inc.)
Each resin composition prepared as described above was combined as shown in Table 1 from the following reinforcing fibers to prepare prepregs of Examples and Comparative Examples.
Reinforcing fiber carbon fiber: "Torayca" (registered trademark) T700SC-12K-50C (tensile strength 4.9 GPa, tensile elastic modulus 235 GPa, fiber specific gravity 1.80, manufactured by Toray Industries, Inc.)
Polyethylene fiber: “Dyneema” (registered trademark) SK60 (manufactured by Toyobo Co., Ltd.)
Each prepreg was produced as follows. A resin film was prepared by applying the resin composition onto the release paper using a reverse roll coater. The amount of resin per unit volume of the resin film is adjusted to the Wf of the target prepreg, and when the Wf is 65%, 72%, 75%, and 78%, the resin amount per unit volume of the resin film is 27 g, respectively. / M ² , 20 g / m ² , 17 g / m ² and 14 g / m ² . Next, the resin film is laminated on both sides of the reinforcing fibers on the reinforcing fibers aligned in one direction in a sheet shape so that the fiber weight per unit area becomes 100 g / m ^2, and heated and pressed to impregnate the resin composition. The unidirectional prepreg was used.

  In each of the examples and comparative examples, each unidirectional prepreg was laminated in the 0 ° direction and heated and pressed at 160 ° C. and a pressure of 0.6 MPa for 10 minutes using a heating press, and the thickness was 1.5 mm. Fiber reinforced composite material plates of 0 mm and 0.2 mm were obtained, and their flame retardancy was measured. Further, a fiber-reinforced composite material having a thickness of 3.0 mm was obtained by the same method as described above, and ILSS was measured.

  The results are shown in Tables 1 and 2. In addition, the number of the resin composition in a table | surface represents a weight part. From the comparison between Examples 1 to 8 and Comparative Example 1, it can be seen that by adding an acid catalyst, the curability of the benzoxazine resin is improved, and the gel time at 150 ° C. is 5 minutes or less. Moreover, it turns out from the comparison with Examples 1-8 and Comparative Example 4 that V-0 and V-1 can be achieved by using a flame-retardant reinforcing fiber such as carbon fiber. Further, from the comparison between Examples 9 and 10 and Comparative Example 6, the gel time at 150 ° C. was increased by adding the acid catalyst regardless of the use of a benzoxazine resin structure or a benzoxazine resin having a different structure. It turns out that it will be 5 minutes or less.

Claims (7)

A prepreg for a composite material composed of a thermosetting resin composition containing the following [A] component and [B] component, and the following [C] component, with respect to 100 weight of the [A] component, [B] A prepreg for a composite material comprising 4 to 20 parts by weight of a component and having a gel time at 150 ° C. of 5 minutes or less.
[A] Benzoxazine resin having a unit structure represented by the following structural formula (I) or (II)

(In the formula, R ₁ represents a chain alkyl group having 1 to 12 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, a phenyl group, or a chain alkyl group having 1 to 12 carbon atoms, or phenyl substituted with halogen. A hydrogen atom bonded to at least one of the ortho and para carbon atoms to which the oxygen atom of the aromatic ring is bonded)

(Wherein R ₂ represents any one of a hydrogen atom, a chain alkyl group having 1 to 12 carbon atoms, and a halogen, and each R ₂ may be the same as or different from each other. X is — CH ₂ -,
A group represented by —C (CH ₃ ) ₂ —, —CH (CH ₃ ) —, —S—, —SO ₂ —, —CO—, —O—, or a structure having no X is selected. Is one)
[B] Acid catalyst [C] Flame retardant reinforcing fiber The prepreg for a composite material according to claim 1, wherein the component (A) is at least one selected from benzoxazine resins represented by the following structural formulas (III) to (XIII).

  The content of the phenol resin which does not have a benzoxazine ring in the molecule in the thermosetting resin composition is 5 parts by weight or less with respect to 100 parts by weight of the component [A]. Prepreg for composite materials.   [B] The prepreg for a composite material according to any one of claims 1 to 3, wherein the component is a boron trichloride complex or a p-toluenesulfonic acid ester.   The prepreg for composite materials according to any one of claims 1 to 4, wherein the fiber mass content (Wf) is 50 to 90%.   [C] The prepreg for a composite material according to any one of claims 1 to 5, wherein the component is carbon fiber.   The fiber reinforced composite material obtained by hardening the prepreg for composite materials in any one of Claims 1-6.