CN1944528B - Epoxy resin for prepreg, prepreg, fiber-reinforced composite material, and processes for producing same - Google Patents

Abstract

The invention provides a prepreg, wherein the center average of roughness height(Ra)of the surface of the fiber reinforced composite sheet is less than or equal to 0.5 um, and the fiber reinforced composite sheet is obtained by thermosetting at the condition of: a forming pressure higher of more than 10kg/cm<2> , a forming time of less than 15 minutes. The invention further provides a fiber reinforced composite sheet is obtained by thermosetting at the condition of: a forming pressure higher of more than 10kg/cm<2> , a forming time of less than 15 minutes, wherein the center average of roughness height(Ra)of the surface of the fiber reinforced composite sheet is less than or equal to 0.5 um. The sheet, which has the advantages of light weight, high rigidity and high strength, is suitable to carrying vehicle and has a surface quality of long life, further has structure, material, and surface properties of FRP outside plate beneficial to the environment.

Description

Epoxy resin for prepreg, fiber-reinforced composite material, and method for producing same

The present application is a divisional application of the chinese patent application entitled "epoxy resin for prepreg, fiber-reinforced composite material, and method for manufacturing the same", which was filed on 28/11/2003 and with application number 200380104284.9.

Technical Field

The present invention relates to an epoxy resin composition, a thermosetting resin composition, a prepreg, a fiber-reinforced composite material, and a method for producing the same. The epoxy resin composition of the present application is particularly suitable for use in prepregs, and can be cured at a relatively low temperature in a short time. Thus, a prepreg having excellent mechanical properties and capable of being stored at room temperature for a long period of time can be obtained. Furthermore, the thermosetting resin composition of the present invention is suitable for high-speed molding, and can exhibit high mechanical properties to a fiber-reinforced composite material (hereinafter, referred to as FRP in some cases) after molding. Thus, by using the composition, a prepreg and a fiber-reinforced composite material molded article which are excellent can be obtained. The excellent prepreg provided by the present invention can be suitably used to obtain a sheet material of a fiber-reinforced composite material that can be used as an outer sheet of a transportation vehicle or an industrial machine. Further, the present invention provides a method for easily producing FRP having high strength and excellent appearance, particularly a method for producing FRP in a short time by compression molding.

The present application is based on 14 years old 346198, 14 years old 347650, 14 years old 353760 and 14 years old 362519 of the japanese patent application, and the contents thereof are incorporated in the present application.

Background

FRP has characteristics of light weight, high strength, and high rigidity, and is widely used from sports and leisure uses such as fishing rods and golf clubs to industrial uses such as automobiles and airplanes.

The method of using a prepreg as an intermediate material in which a resin is impregnated into a reinforcing material made of fibers such as reinforcing fibers is suitable as a method for producing FRP because the content of the reinforcing fibers in the prepreg can be easily controlled and can be designed to be high.

Specific methods for obtaining FRP from prepreg include a method using an autoclave as disclosed in JP-A-10-128778, a method using a vacuum bag as disclosed in JP-A-2002-159613, and a compression molding method as disclosed in JP-A-10-95048.

However, in any of these methods, when the prepreg is laminated, and is heat-cured after being shaped into a desired shape, it takes about 2 to 6 hours for curing under a condition of about 160 ℃ or higher. I.e., requiring high temperatures and long processing times.

However, in order to mass-produce products, it is required that the molding can be carried out at a relatively low temperature of about 100 to 130 ℃ and in a short time of about several minutes to several tens of minutes. One of the methods for achieving this object is to use an epoxy resin composition which starts a curing reaction with a small amount of heat, thereby shortening the time until the curing of the epoxy resin composition is completed. However, if the reactivity is too high, the curing reaction is liable to be out of control, which is dangerous. However, when a conventionally used curing agent is used, mechanical properties may be deteriorated if the amount of the curing agent is increased. Further, such an epoxy resin composition has a short pot life and may be cured by storage at room temperature for only several days. Thus, development of epoxy resin compositions having desirable reactivity has been desired.

Next, the following conditions may be mentioned, if appropriate, in view of the conditions required for the prepreg.

Excellent workability such as good tackiness (sticky state) at around room temperature and moderate drapability (flexibility);

the FRP can maintain the workability for a long time, i.e., has a long life at around room temperature, and the FRP after molding is excellent in mechanical properties and thermal properties.

Prepregs, which are formed by impregnating reinforcing fibers with a matrix resin such as an epoxy resin composition and are widely used as intermediate materials for fiber-reinforced composite materials, are used in various fields, but are particularly required to have excellent moldability in the case of the above-mentioned industrial applications.

At present, a general prepreg requires heating and curing for about 1 hour, and if the prepreg includes a time for raising and lowering the temperature as described above, a primary molding requires about 2 or 3 to 6 hours depending on the conditions, which is extremely long, and this causes an increase in molding cost.

However, if the heating time required for molding is shortened, the life at around room temperature is shortened, and there is a problem that the molding temperature must be extremely high. Development of thermosetting resin compositions that impart excellent properties to prepregs is also in progress.

Next, the characteristics of the SMC and the prepreg and the FRP sheet will be described.

Many materials for FRP other than prepreg are molded using a molding material such as sheet molding compound (hereinafter referred to as SMC). However, in the production of FRP, it is advantageous to use a prepreg (hereinafter referred to as UD prepreg) or a woven prepreg, which is formed by aligning substantially continuous reinforcing fibers in one direction, as compared with SMC having several places to be improved, which will be described later, particularly in terms of the strength of FRP.

However, in order to efficiently obtain more excellent FRP, a prepreg used at present needs to be newly improved.

FRP plates are excellent in corrosion resistance, and thus have been tried to be used as outer plates of transportation vehicles including automobiles and various industrial machines. FRP plates called SMC, for example, are widely used for outer panels of automobile hoods, fenders, and the like.

SMC (for example, refer to japanese unexamined patent publication No. h 6-286008) is a pasty intermediate substrate obtained by mixing reinforcing fibers of short fibers of carbon fibers or glass fibers with a polyester resin or the like. Heating it and pressing it in a mold under high pressure (usually 50kg/cm or more)²) And shaping to manufacture the bottom plate of the outer plate. Next, the surface of the base plate is ground with sandpaper or a file to be flat and smooth, and then color-coated to form, for example, an FRP outer panel for automobiles.

Since the reinforcing fibers of the outer sheet made of SMC are short fibers (discontinuous fibers), the rigidity is lower than that of the case where the reinforcing fibers are continuous fibers (not only short fibers are reinforcing fibers, but also the elastic modulus of glass is 70GPa, which is as low as 1/3 of the elastic modulus 210GPa of steel). Therefore, the outer panel is larger in plate thickness than the metal outer panel, and may not necessarily be lighter in weight than the metal outer panel, and may be reduced in weight. Further, since the SMC outer panel has discontinuous fibers, the strength, which is an important characteristic other than the rigidity of the outer panel, is low, and particularly, the outer panel is easily damaged by local impact penetration such as impact from a flying object. Therefore, it is necessary to further increase the thickness of an outer panel used outdoors for transportation means or the like, or to take measures against impact such as adhesion of rubber. Thus, it is not possible to form a lightweight outer panel that can replace a metal outer panel in terms of weight, that is, an environmentally friendly outer panel for transportation.

However, many of the outer panels formed of SMC have been put into practical use mainly because the short fibers are randomly (substantially uniformly) dispersed, and therefore, the aforementioned base plate before grinding is likely to have substantially uniform surface quality. When continuous fibers are used, the surface of the base plate has a short undulation and large fibers due to unevenness in fiber distribution and unevenness in thickness caused by meandering, undulation, interlacing of fibers with each other, and the like of the fibers. Thus, for this case, the following problems arise:

1) the labor for the above-described grinding work is large;

2) the continuous reinforcing fibers are also ground off during grinding, thereby further reducing the mechanical and functional properties of the outer panel.

However, continuous fibers are preferable because they have higher physical properties in terms of rigidity and strength and can produce lightweight FRP panels. However, the form of the continuous fiber is complicated and various, such as unidirectional prepreg, woven fabric, and three-dimensional woven fabric, but none of them has been put to practical use.

On the other hand, a member using continuous fibers as reinforcing fibers is also under study. The parts are manufactured by Resin Transfer Molding (RTM) or the like, in which a prepreg formed of continuous fibers and a resin aligned in one direction is laminated on a mold and cured by an autoclave or the like, or a preform of a fabric or the like is placed in the mold and the resin is injected. However, the surface quality is low due to unevenness and unevenness in thickness caused by the meandering, waving, and interlacing of the fibers inherent to the continuous fibers, and the like, and thus the outer panel has not been practically used as an outer panel for a transportation means such as an automobile.

In order to improve the surface quality, a coating method called gel coat is used. The gel coat method (refer to Japanese unexamined patent publication No. 11-171942) is a method in which a resin material coating layer such as polyester, which can be an outer plate surface, is formed in advance on the inner surface of a mold, a reinforcing fiber base material is placed on the coating layer, and the mold is closed; subsequently, a resin is injected and cured, and the coating is transferred to the surface of the FRP outer panel after releasing the mold. The method is advantageous for industrialization because grinding and finishing of the surface can be omitted. However, when the FRP and the gel coat are cured by heating, deformation such as warpage of the entire molded article occurs due to a difference in linear expansion coefficient between the FRP and the gel coat. Thus, it is not suitable for an outer panel requiring precision, and is not suitable for an outer panel due to cracking or wrinkling of the gel coat.

Further, since the surface of FRP using continuous fibers as reinforcing fibers has irregularities as described above, the thickness of the gel coat layer is 200 μm or more, which is thicker than the coating film in the case of coating. Therefore, there is a drawback in that not only the weight is increased but also the gel coat is broken or peeled off when the outer panel is deformed by an external force, thereby being unsuitable for the outer panel.

In the case of a gel coat layer of an outer panel used outdoors, moisture such as rainwater enters the interior of FRP due to cracking or peeling of the gel coat layer, and the lightweight property and durability which are the characteristics of FRP may be impaired. In addition, in the case of the gel coat, selection of colors is extremely small as compared with the coating, and appearance rich in metallic feeling and fashion is not produced. Therefore, there is a problem that it cannot be applied to an outer panel such as an automobile outer panel which is required to be colored with other parts because the value of the entire product is reduced. Coating of the gel coat layer is also considered, but this case causes problems such as further increase in weight and cost.

In order to improve the surface quality, other attempts have been made to adjust the coverage factor of the carbon fiber fabric used as the reinforcing fiber (see japanese unexamined patent publication No. 2001-322179).

However, it is difficult to maintain the coverage factor within an appropriate range because the carbon fiber woven fabric is subjected to various processes such as processing into an intermediate material, cutting, laminating, and preforming into FRP after being woven. If the movement of the carbon fiber is restrained by caulking, the cover factor can be maintained in a suitable range, but since the carbon fiber is restrained, there is a defect that it is very difficult to obtain a curved shape of FRP.

As described above, in the actual situation, there are few examples in which an FRP plate material using a prepreg, that is, a prepreg in which reinforcing fibers are continuous fibers is particularly put into practical use as an outer plate, and quantitative indexes of the structure and surface quality of an FRP plate material having practical use are not established.

The linear expansion coefficient of FRP in the thickness direction is larger than that of metal. Therefore, if the surface smoothness is poor, rainwater or the like stays due to deformation caused by temperature change, and the coating is deteriorated to generate spots due to a lens effect by light such as ultraviolet rays, thereby forming an outer plate having a spot pattern.

The surface quality of the outer panel is known to have an important influence on the fluid resistance against air and water in addition to the commercial value and long-term durability described above. Therefore, it is necessary to improve the surface quality of all transportation vehicles such as trains, small airplanes, boats, ships, and the like, not only for automobiles, but also for energy saving. In general, if an outer panel is made of FRP for weight reduction, the elastic modulus is lower than that of metal, and therefore, a large deformation occurs against air resistance received during high-speed movement of a vehicle, and a large change occurs in flow resistance. Therefore, a standard different from that of the metal material should be set independently for the surface of the FRP panel.

Repeatedly, in order to put an FRP panel using continuous fibers into practical use, there is an urgent need to establish a comprehensive technique suitable for the structure, material, and surface quality of an FRP panel.

The following describes a manufacturing method.

As a method for obtaining FRP from a molding material, a method using an autoclave, a method using a vacuum bag, a compression molding method, and the like are known as described above. In particular, the compression molding method is suitable for mass production of FRP having good appearance and high strength because it can be completed in a relatively short molding time as compared with molding methods using an autoclave and a vacuum bag. In addition, this method has an advantage that it is easy to manufacture FRP having a complicated shape because it is easy to process a mold.

However, when FRPs are produced by a compression molding method using a molding material containing continuous reinforcing fibers as a reinforcing material, the resin having a reduced viscosity rapidly flows into or on the FRPs due to pressurization. And due to this flow, the arrangement of the reinforcing fibers is disturbed, resulting in so-called coil bending. Therefore, not only the appearance is deteriorated due to the bending of the coil at the surface portion, but also the mechanical properties of the FRP are lowered due to the bending of the coil at the inside caused by the disorder of the arrangement of the reinforcing fibers at the surface portion. Therefore, the production of FRP by compression molding is limited to the case of using SMC or the like as disclosed in JP-A-10-95048.

Disclosure of Invention

The present inventors have assiduously studied and, as a result, have provided 4 types of means for achieving the problems described below.

One of the objects of the present invention is to provide an epoxy resin composition which can be cured in a short time even at low temperature and can ensure a sufficient usable period even when stored at room temperature, as compared with conventional epoxy resin compositions; and a fiber-reinforced composite material which is obtained from a prepreg obtained using the resin and exhibits excellent mechanical properties. This is achieved by the following first invention.

That is, according to a first aspect of the present invention, there is provided an epoxy resin composition comprising the following components A, B, C and D, wherein the contents of a sulfur atom and C in the epoxy resin composition are 0.2 to 7% by mass and 1 to 15% by mass, respectively.

Component A: epoxy resin

And B component: an amine compound having at least one sulfur atom in the molecule (component B-1) and/or a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in the molecule (component B-2)

And C, component C: urea compounds

And (D) component: dicyandiamide

Among the above epoxy resin compositions, those having a gel time of 200 seconds or less at 130 ℃ can be particularly preferably used.

The present inventors also provide an epoxy resin composition according to the first aspect, which comprises a component B-2, a component C and a component D, which are reaction products of an epoxy resin and an amine compound having at least one sulfur atom in a molecule, wherein the contents of the sulfur atom and the component C in the epoxy resin composition are 0.2 to 7 mass% and 1 to 15 mass%, respectively.

B-2 component: reaction product of epoxy resin and amine compound having at least one sulfur atom in molecule

And C, component C: urea compounds

And (D) component: dicyandiamide

Further, the present inventors provide a method for producing an epoxy resin composition according to the first aspect, wherein the content of the component C in the epoxy resin composition is 1 to 15% by mass when the epoxy resin composition is obtained by mixing 100 parts by mass of the component a and 0.2 to 7 parts by mass of the component B-1 and then further mixing the component C and the component D.

Component A: epoxy resin

And B component: amine compound having at least one sulfur atom in the molecule (component B-1)

And C, component C: urea compounds

And (D) component: dicyandiamide

Another object of the present invention is to provide a thermosetting resin composition suitable for a prepreg having a characteristic that it can be molded at high speed required for industrial use, in addition to the characteristics of a conventional prepreg that it is excellent in handleability at room temperature and long life at room temperature and can maintain good physical properties after molding. Also disclosed is a prepreg obtained by impregnating such a thermosetting resin composition with the prepreg, and a method for producing an FRP using such a prepreg and having excellent mechanical strength and thermal properties at high speed.

This problem is achieved by the following second aspect.

Namely, a second embodiment of the present application, a thermosetting resin composition having a viscosity of 5X 10 at 50 ℃¹～1×10⁴Pa sec, and reaches 1X 10 in 1000 seconds or less in an atmosphere of 120 DEG C⁶Pa sec, which has a viscosity increase of 2-fold or less at 50 ℃ after being left at 30 ℃ for 3 weeks.

Another object of the present invention is to solve the overall problems of the FRP panel using continuous fibers, particularly the structure, material, and surface of the outer panel. That is, an FRP panel is provided which has not only light weight, high rigidity and high strength suitable for transportation and the like, but also surface quality that can withstand long-term use and has the structure, material and surface properties of an FRP outer panel that are environmentally friendly. This problem is achieved by the following third aspect.

That is, according to the third aspect of the present invention, (1) the molding pressure is 10kg/cm or more²A prepreg having a surface of an FRP sheet material obtained by heat curing for a molding time of 15 minutes or less and a center average roughness (Ra) of 0.5 [ mu ] m or less; (2) at a forming pressure of 10kg/cm or more²And an FRP sheet material obtained by heat-curing for 15 minutes or less, wherein the surface of the FRP sheet material has a center average roughness (Ra) of 0 or less.5 μm FRP sheet material.

It is still another object of the present invention to produce FRP having high strength and excellent appearance in a short time by compression molding, which uses substantially continuous reinforcing fibers as a reinforcing material. This problem is achieved as follows.

That is, according to a fourth aspect of the present invention, there is provided a method for producing a fiber-reinforced composite material molded article, comprising the steps of: adjusting the temperature of the molding die to a temperature equal to or higher than the curing temperature of the thermosetting resin in advance; in the forming mold (single surface area S)₂) A molding material (single-sided surface area S) obtained by impregnating substantially continuous reinforcing fibers with a thermosetting resin is put in₁) A step (2); a step of closing the forming mold to fill the entire inside of the forming mold with the forming material; compression molding to S₁/S₂0.8 to 1.

Drawings

FIG. 1A is a sectional view showing a state where a molding material is placed inside a mold before the mold is closed;

FIG. 1B is a sectional view showing a state where the mold is closed;

fig. 2 is a cross-sectional view showing a common edge structure of portions where an upper die and a lower die (a male die and a female die) are in contact when the dies are closed, which is preferably used for a die used in a fourth embodiment of the present invention;

fig. 3 is a sectional view showing an openable and closable hole provided in a mold which is preferably used in a mold used in a fourth embodiment of the present invention. Blowing air through the holes can also be used for releasing the FRP.

Detailed Description

The first to fourth aspects of the present invention will be described in detail below.

First mode

The first embodiment of the present invention will be described below, and the components and additives, the production method, and further, the prepreg obtained from the epoxy resin, and the like will be described in detail.

The present embodiment provides an epoxy resin composition which can be cured in a short time even at a low temperature and can ensure a sufficient usable time even when stored at room temperature, as compared with conventional epoxy resin compositions. The prepreg obtained using the resin can provide a fiber-reinforced composite material exhibiting excellent mechanical properties.

(A component)

The component a in the first embodiment is an epoxy resin. Examples of the difunctional epoxy resin include a bisphenol a type epoxy resin, a bisphenol F type epoxy resin, a biphenyl type epoxy resin, a dicyclopentadiene type epoxy resin, and an epoxy resin obtained by modifying these resins. Examples of the trifunctional or higher polyfunctional epoxy resin include, but are not limited to, a novolak-type epoxy resin, a cresol-type epoxy resin, a glycidyl amine-type epoxy resin such as tetraglycidyl diaminodiphenylmethane, triglycidyl aminophenol, and tetraglycidyl amine, a glycidyl ether-type epoxy resin such as tetrakis (glycidyl oxyphenyl) ethane and tris (glycidyl oxymethane), an epoxy resin obtained by modifying these resins, and a brominated epoxy resin obtained by brominating these epoxy resins. Further, as the component A, 1 or more of these epoxy resins may be used in combination.

In particular, bisphenol a type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, novolac type epoxy resins, and cresol novolac type epoxy resins can be particularly preferably used. These epoxy resins have an effect of further improving the mechanical strength of the molded article, as compared with the case of using an epoxy resin having high rigidity, such as an epoxy resin having a naphthalene skeleton in the molecule. This is because, if an epoxy resin having high rigidity is cured in a short time, strain is likely to occur due to an increase in crosslinking density, and conversely, if the above-mentioned epoxy resin is used, there is a low possibility that such a problem occurs.

On the other hand, as the epoxy resin having a sulfur atom in the molecule, there are a bisphenol S type epoxy resin and an epoxy resin having a sulfur skeleton, and they can be used in the present invention. However, in the present invention, in order to effectively use these substances, it is necessary to quantify the content of sulfur atoms in the epoxy resin composition. As a method for quantifying the content of sulfur atoms in the epoxy resin composition in advance, atomic absorption spectrometry or the like can be used.

(component B)

The component B of the first embodiment is an amine compound having at least one sulfur atom in the molecule (component B-1) and/or a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in the molecule (component B-2).

The component B-1 is not particularly limited as long as it is an amine compound having at least one sulfur atom in the molecule, and for example, 4 '-diaminodiphenyl sulfone, 3' -diaminodiphenyl sulfone, 4 '-diaminodiphenyl sulfide, bis (4- (4-aminophenoxy) benzene) sulfone, bis (4- (3-aminophenoxy) benzene) sulfone, 4' -diaminodiphenyl sulfide, o-tolidine sulfone, and derivatives thereof are preferably used.

On the other hand, the component B-2 is a reaction product of the above epoxy resin and an amine compound having at least one sulfur atom in the molecule. In the epoxy resin composition of the present embodiment, a mixture containing the component B-2 can be obtained by mixing and reacting the component A and the component B-1, but it is not necessary to separate the component B-2 separately from them.

In addition, in the process of producing the epoxy resin composition of the present embodiment, part or all of the substances added as the A component and the B-1 component may be changed to the B-2 component.

At this time, one or both of the A component and the B-1 component may be consumed to change to the B-2 component.

In this embodiment, either of the components B-1 and B-2 can be used, but when the component B-2 or a mixture of the components B-1 and B-2 is used, the storage stability can be improved.

(component C)

The component C in this embodiment is a urea compound.

The component C is not particularly limited, but urea compounds such as dichlorodimethylurea and phenyldimethylurea are preferably used. In particular, a substance having no halogen atom in the molecule is particularly suitable for use as the component C because it has high reactivity and low toxicity.

The urea compound in the present invention may contain an amide of carbonic acid or an amide of carbamic acid. Generally, phosgene, chloroformate, carbamoyl chloride, carbonate, isocyanate, cyanic acid and amine such as ammonia are used.

Compounds generally called ureas such as ureides (acylureas) obtained by reacting urea with an acid chloride and alkylureas (alkylureas) obtained by substituting hydrogen of urea with a hydrocarbon group are also included in the urea compounds of the present invention.

The urea compound in this embodiment also includes a urea adduct.

The urea adduct is a product obtained by mixing a saturated aqueous solution of a hydrocarbon and urea or a saturated solution of a lower alcohol such as methanol and introducing a hydrocarbon into the crystal structure of urea.

The content of the component C in the epoxy resin composition is required to be 1 to 15 mass%. Preferably 3% by mass or more, and preferably 12% by mass or less. If less than 1 mass%, the curing reaction may not be sufficiently completed; if the amount exceeds 15% by mass, the pot life is short and long-term storage at around room temperature may not be possible.

Further, when a solid material is used as the component C, the average particle diameter is preferably 150 μm or less, and more preferably 50 μm or less. If the average particle size exceeds 150 μm, the dispersion rate of the particles decreases, and as a result, the rate of the curing reaction decreases, and curing in a short time, which is the most important effect of the present invention, may not be achieved.

(component D)

In the first embodiment, the component D is dicyandiamide. The dicyandiamide functions as a curing agent for epoxy resin, and can be cured at a relatively low temperature by being used in combination with other components in the present embodiment.

In this embodiment, the content of the component D in the epoxy resin composition is preferably 0.1 to 10% by mass. Further, it is preferable that the average particle diameter of the component D is not more than 150 μm, particularly not more than 50 μm, since the dispersibility is good and the reaction rate is high.

(other additives)

In the epoxy resin composition of the first embodiment, an appropriate amount of inorganic fine particles such as fine powdery silica, a pigment, an elastomer, aluminum hydroxide, bromide or a phosphorus compound as a flame retardant, a defoaming agent, a thermoplastic resin dissolved in an epoxy resin such as a polyvinyl acetal resin and a phenoxy resin for the purpose of improving workability and flexibility, an imidazole derivative as a catalyst for a curing reaction, a metal complex salt or a tertiary amine compound, and the like may be added.

(content of sulfur atom in epoxy resin composition)

In the epoxy resin composition of the first embodiment, the content of the sulfur atom in the epoxy resin composition must be 0.2 to 7% by mass. If it is less than 0.2% by mass, curing is difficult to complete at low temperature in a short time; if it exceeds 7 mass%, the usable period may be shortened.

(gel time)

The epoxy resin composition of the first embodiment preferably has a gel time of 200 seconds or less at 130 ℃. In this embodiment, the gel time means a time until gelation is completed when a specific temperature is raised for the uncured epoxy resin composition. Here, gelation means a state in which the epoxy resin composition loses fluidity by forming a three-dimensional network structure between molecules.

The epoxy resin composition having a gel time of 200 seconds or less at 130 ℃ can be cured particularly in a short time.

(method for producing epoxy resin composition)

In the method for producing the epoxy resin composition of the present embodiment, the above-mentioned components A, B-1, C, D and other additives may be added in appropriate amounts and mixed. In this case, as described above, part or all of the components A and B-1 added may be reacted to change to the component B-2.

Further, the component A and the component B-1 may be mixed in advance to prepare a resin composition containing the component B-2, and then the component C and the component D may be mixed.

The temperature during mixing is preferably 50 to 180 ℃, and more preferably 60 to 160 ℃.

(prepreg)

By impregnating the reinforcing fibers with the epoxy resin composition as a matrix resin, a prepreg which can be molded at a relatively low temperature in a short time can be obtained. The prepreg can be produced by a known apparatus and a known production method.

The reinforcing fiber applicable to the first embodiment is not particularly limited, and various fibers can be used depending on the purpose of use of the composite material. For example, carbon fibers, graphite fibers, aramid fibers, silicon carbide fibers, alumina fibers, boron fibers, tungsten carbide fibers, glass fibers, and the like are preferably used. Also, these plural kinds of reinforcing fibers may be used in combination.

Among these reinforcing fibers, carbon fibers and graphite fibers have a good specific elastic modulus and are important for weight reduction, and therefore, they are suitable for the present invention. In addition, depending on the application, all kinds of carbon fibers and graphite fibers can be used, but a tensile strength of 3500Ma or more and a tensile elastic modulus of 190GPa or more are particularly preferable.

The form of the reinforcing fibers in the prepreg is not particularly limited, and may be a form in which the reinforcing fibers are aligned in one direction, a form in which the reinforcing fibers are woven, or a nonwoven fabric using chopped reinforcing fibers. In particular, in the case of the aligned form in one direction and the woven form, the molding by the compression molding method has taken time until the resin is cured, and thus the resin flows in the mold, and a fiber-reinforced composite material having good appearance cannot be obtained. However, when the epoxy resin composition of the present embodiment is used, the epoxy resin composition is cured in a short time, and thus a fiber-reinforced composite material having good appearance can be obtained.

Second mode

A second embodiment of the present invention will be described below, and specific descriptions of the respective sentences, preferred examples of the present embodiment, and the like are described in detail.

According to the second aspect, there is provided a thermosetting resin composition which is suitable for a prepreg which is excellent in handleability at room temperature and long-life at room temperature, maintains good physical properties after molding, and can be molded at high speed required for industrial use.

[ measurement of viscosity ]

The present inventors have assiduously studied in order to solve the above-mentioned problems, and as a result, have confirmed that the viscosity of the thermosetting resin composition, the time until the composition reaches a target viscosity in a heated state (specifically, 120 ℃), and the viscosity after leaving the composition are important. In the second embodiment, the viscosity was measured using RDS-200 (a dynamic viscosity measuring apparatus having equivalent performance) manufactured by Rheometrics, and the obtained value was measured at a frequency of 1Hz using a parallel plate of 25mm φ. The temperature raising condition to the temperature of the heated state (specifically, 120 ℃ C.) is described in detail in the section.

[ viscosity at 50 ℃ 5X 10%¹～1×10⁴Pa·sec]

The thermosetting resin composition of the second embodiment is required to have a viscosity of 5X 10 at 50 ℃¹～1×10⁴Pa·sec。

When the viscosity is less than 5X 10¹Pa · sec results in excessively strong viscosity at around room temperature when a prepreg is prepared, and handling becomes extremely difficult. In contrast, the viscosity exceeded 1X 10⁴Pa sec is a point where the drape of the prepreg is lost and the prepreg becomes hard and still difficult to handle.

[ 1X 10 in 1000 seconds or less in an atmosphere of 120 DEG C⁶Pa·sec]

Next, in the second mode, the thermosetting resin composition must be at 120 ℃ for 1000 seconds or less to reach 1X 10⁶Pa·sec。

Until the viscosity reaches 1X 10⁶When the time of Pa sec exceeds 1000 seconds, the molding time at high temperature is long. When 800 seconds or less, the molding time at high temperature is short, and therefore, is preferable, and more preferably 600 seconds or less.

The measurement method is used in the measurement of [ viscosity ]]The method described in (1) above is carried out under the following temperature-raising conditions to a temperature of a heated state (specifically, 120 ℃). That is, after fixing a thermosetting resin composition sample at 50 ℃, the temperature was raised to 120 ℃ at a temperature rise rate of 10 ℃/min, and the isothermal viscosity was measured at 120 ℃. Starting from the time point when the temperature reached 120 ℃, the time was counted until the viscosity reached 1X 10⁶The time of Pa sec is counted. Up to 1 × 10⁶When the viscosity of Pa sec is difficult to measure, the lowest viscosity can be measured at 1X 10²Viscosity of about Pa sec, and the last 2 points are extrapolated to 1 × 10⁶Time of Pa · sec. But even the lowest one needs to implement 1-bit number or 1-bit numberThe above viscosity measurement. That is, by the insertion of 1 × 10²Determination of Pa sec data 1X 10⁶Pa sec, the viscosity at 120 ℃ must be 1X 10 or less¹Pa·sec。

[ increase in viscosity at 50 ℃ by 2-fold or less after standing at 30 ℃ for 3 weeks ]

Further, the thermosetting resin composition of the second embodiment is required to have a viscosity increase at 50 ℃ of 2 times or less after being left at 30 ℃ for 3 weeks.

The method of measuring the viscosity is the same as [ measurement of viscosity ]. When the viscosity increases more than 2 times, the stability of the prepreg at around room temperature is deteriorated.

[ resin composition ]

The raw material of the thermosetting resin composition of the second embodiment is not particularly limited, and an epoxy resin, a phenol resin, a vinyl ester resin, an unsaturated polyester resin, a bismaleimide triazine resin, a cyanate resin, a benzoxazine resin, an acrylic resin, and the like can be exemplified, but from the viewpoints of workability and cured product physical properties, an epoxy resin, a bismaleimide triazine resin, and a cyanate resin are preferably used, and particularly, an epoxy resin and a reinforcing material are preferably used because they are excellent in adhesion.

The thermosetting resin composition of the present embodiment may contain a thermoplastic resin and other additives for the purpose of improving the handleability of the prepreg, improving the appearance of the molded FRP, and improving the physical properties such as impact resistance.

Examples of the thermoplastic resin that can be suitably added to the second embodiment include aromatic polyamide, polyester, polyacetal, polycarbonate, polyphenylene ether, polyphenylene sulfide, polyarylate, polyimide, polyetherimide, polysulfone, polyamide, polyamideimide, polyether ether ketone, and the like.

Examples of the other additives include synthetic rubbers such as butyl rubber, isoprene rubber, nitrile rubber, and silicone rubber, which are elastomers, and natural rubbers such as latex.

[ addition of Filler ]

In order to improve the surface smoothness of the resulting FRP, a filler such as a filler is preferably added to the thermosetting resin composition of the second embodiment. Calcium carbonate is preferable as the filler, and the particle size of calcium carbonate is preferably 3 to 10 μm.

The amount of the filler to be added varies depending on the kind of the resin of the thermosetting resin composition, but is preferably 10 to 300 parts by mass relative to 100 parts by mass of the thermosetting resin composition.

It is needless to say that, when the above-mentioned additive is added to the thermosetting resin composition of the present embodiment, the thermosetting resin composition finally impregnated into the prepreg must satisfy the above-mentioned viscosity condition.

[ prepreg ]

The prepreg of the second embodiment is formed by impregnating the thermosetting resin composition of the present invention into a reinforcing material. The material of the reinforcing material used in the prepreg of the present embodiment is not particularly limited, and examples thereof include carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers, boron fibers, steel fibers, and the like, but carbon fibers and glass fibers that can obtain excellent FRP performance, particularly mechanical properties of light weight, high strength, and high rigidity are preferably used.

The form of the reinforcing material used in the prepreg of the second embodiment is not particularly limited, and examples thereof include a woven fabric or a woven fabric sheet such as a non-woven fabric (non-woven fabric) obtained by sewing an object in which plain woven fabric, twill woven fabric, satin woven fabric, or fiber bundles are laminated in one direction or at a different angle so as not to unravel, a non-woven fabric or a spacer-like object, and a unidirectional material obtained by aligning reinforcing fibers in one direction.

The resin content of the prepreg of the present embodiment is not particularly limited, but the smaller the resin content, the better the appearance of the resulting FRP and the greater the reinforcing effect of the reinforcing material, and therefore, the prepreg is preferable. Specifically, the volume content of the thermosetting resin composition in the prepreg is preferably 45 vol% or less, more preferably 40 vol% or less, and particularly preferably 35 vol% or less.

The lower limit of the volume content of the thermosetting resin composition in the prepreg is not preferable because if the content of the thermosetting resin composition is too small, the thermosetting resin composition may not be filled in each corner of the FRP. Specifically, the content of the thermosetting resin composition is preferably 20% by volume or more, more preferably 25% by volume or more.

[ method for producing FRP ]

A second method for producing FRP is a method for producing FRP in which the prepreg of the present embodiment is placed in a mold, and the mold is closed and heated and pressurized. The forming die is not particularly limited, but a metal forming die is preferable because it is difficult to deform even when a high pressure is applied.

The heating temperature is also not particularly limited, but is preferably as the higher the temperature is, the shorter the molding time is. Specifically, it is preferably 120 ℃ or higher, more preferably 140 ℃ or higher. However, if the temperature is too high, it takes a long time to lower the temperature of the molding die, or when the prepreg is left without lowering the temperature, the resin may not reach the corners of the final molded product due to the start of curing. Therefore, the heating is preferably 200 ℃ or less, more preferably 180 ℃ or less. The degree of pressurization is also not particularly limited, but the high-pressure molding is preferable because pinholes on the surface and voids inside the FRP can be reduced. Specifically, the pressure applied to the prepreg is preferably 0.5MPa or more, and more preferably 1MPa or more. An upper limit of 100MPa is sufficient.

The equipment and the form of molding are not particularly limited, but the method using a hydraulic heating and pressing equipment is most efficient and suitable for the method for producing FRP of the present invention. The molding die in this case is preferably a molding die having a closed system with a common edge structure.

Third mode

The third embodiment of the present invention will be described below.

In the third aspect, a prepreg and an FRP sheet are provided which are superior in that they can solve the overall problems of the structure, material, and surface of an FRP sheet using continuous fibers, particularly as an outer sheet.

< prepreg >

[ Forming pressure ]

The prepreg of the third embodiment is required to have a surface quality of 10kg/cm or more in order to have a good surface quality of 0.5 μm or less in the centerline average roughness (Ra) of the FRP sheet and to have a surface quality capable of withstanding long-term use²The molding pressure of (3) is to mold a prepreg in which a matrix resin is impregnated into substantially continuous reinforcing fibers.

The pressure during molding is less than 10kg/cm²In this case, it is difficult to form a good surface quality.

[ Forming time ]

In the third aspect, in order to obtain an FRP panel for use in transportation facilities with particularly high cost consciousness, it is necessary to heat-cure the FRP panel for a molding time of 15 minutes or less, and more preferably 10 minutes or less. In the present invention, the molding time is a time during which the prepreg is left in a state where the molding temperature and pressure are applied.

[ reinforcing fiber ]

The type of the reinforcing fiber that can be used in the third embodiment is not particularly limited as long as it is a substantially continuous reinforcing fiber, and carbon fibers, glass fibers, aramid fibers, polyester fibers, boron fibers, and the like can be used. Among them, carbon fibers having a higher specific strength than elasticity can be optimally used as parts of aircrafts, automobiles, and the like.

The form of the reinforcing fibers in the molding material is not particularly limited, and may be a form in which the reinforcing fibers are aligned in one direction, a form in which the reinforcing fibers are woven, or the like. For example, in order to improve the appearance of FRP, the molding material on the surface of FRP may be reinforced with a woven fabric of reinforcing fibers, and a plurality of reinforcing forms may be used in which reinforcing fibers are aligned in one direction inside the FRP.

In the present specification, the substantially continuous reinforcing fibers mean fibers having substantially no end portion inside the molding material.

In the prepreg of this embodiment, carbon fibers are preferably used as the reinforcing fibers. Any of PAN (acrylonitrile) and pitch can be used for the carbon fiber. The PAN-based carbon fiber is more preferable in terms of the balance of strength, elastic modulus, and elongation in the production of a woven fabric. For the purpose of outer plate, carbon fibers having an elongation of 1.4% or more are preferred because they have higher strength and higher elastic modulus, and they have impact resistance. The elongation of FRP is determined in accordance with JIS K-7054, and strictly speaking, it means tensile strain at break.

[ carbon fiber Fabric ]

The carbon fiber woven fabric is formed in a continuous fiber state into a woven fabric form such as a plain weave, a twill weave, a satin weave, or the like. Among them, the woven fabric of the present invention is preferably a woven fabric of carbon fibers having a mass per unit area (Wg/m)²) The ratio (W/t) to the thickness (tmm) is in the range of 700 to 1700.

Fabrics in this range are referred to as tissue fabrics, which are relatively thin in terms of mass per unit area and have a structure in which fibers are spread. Since the fiber has small undulations in the thickness direction, it can exhibit high strength and rigidity, making the outer panel more lightweight. Further, since the unevenness of the fabric surface is small, the surface quality of the outer panel is also improved, and the durability of the FRP panel is also improved. Further, the mass per unit area and the thickness of the fabric were measured according to JIS R7602.

Further, when the coverage factor of the carbon fiber woven fabric is in the range of 90 to 100%, the portion formed of only the resin is extremely small, the out-of-plane impact characteristics are high, and surface irregularities or irregularities caused by shrinkage of the resin in the thickness direction disappear, and high image clarity is obtained, which is preferable. In the penetration impact, if a case where the flying object is a small piece is also assumed, the coverage factor is more preferably in the range of 95 to 100%.

The cover factor Cf of the carbon fiber woven fabric is a factor relating to the size of the voids formed between the spun yarns, as described and defined in japanese unexamined patent publication No. h 7-118988, and when the area S is set in the woven fabric, if the area of the voids formed between the yarns for weaving in the area S is set to S, it is a value defined by the following formula.

Coverage factor Cf { (S-S)/S } × 100 { (S-S) (%) ]

In addition, since the fabric contributes to surface rigidity and surface quality which are particularly important in physical properties of the outer panel, the position of the fabric is preferably in the vicinity of the surface layer of the panel. The presence of the carbon fibers having high rigidity in the surface layer of the outer panel further improves the surface rigidity of the outer panel, thereby enabling weight reduction.

The most preferred location is the outermost layer. Further, if a multiaxial fabric such as a biaxial or triaxial fabric is disposed as the outermost layer, it is also possible to impart a unique fabric appearance to the outer panel. Further, by positioning the fabric having the relationship between the mass per unit area and the thickness in the above range as the outermost layer, the surface of the outer panel becomes extremely smooth, and also extremely smooth when a thin coating film is provided.

I.e., mass per unit area (Wg/m) of the carbon fiber woven fabric²) The thin fabric having a ratio (W/t) to thickness (tmm) in the range of 700 to 1700 has small unevenness and small meandering along the thickness direction of the fiber, so that the thickness variation of the resin layer on the surface is small when the fabric is formed into an outer panel, and a smoother surface can be obtained before and after coatingAnd (5) kneading.

Further, if the coverage factor is in the range of 90 to 100%, it is preferable that the portion composed of only resin is not present in the thickness direction of the outer plate, and the property which is extremely important in terms of durability, such as the image clarity, is improved, and the practicability is increased.

[ reinforcing fibers other than carbon fibers ]

In the present invention, in addition to carbon fibers, inorganic fibers such as glass fibers, alumina fibers, and silicon nitride fibers, aramid fibers, and organic fibers such as nylon may be used in combination. By arranging such long fibers, short fibers, woven fabric-like or spacer-like objects, or a mixture thereof regularly or irregularly in the carbon fibers or the resin, impact resistance, shock absorption characteristics, and the like can be improved.

In particular, glass fibers are inexpensive and have a good balance of compressive and tensile strengths. The glass fiber is silicon dioxide (SiO)₂) The fibrous glass such as E glass, C glass, S glass, etc. as the main component is preferably glass fiber having a fiber diameter of about 5 to 20 μm. The glass cloth has good moldability because it can hold resin while increasing rigidity. The mass per unit area of the fabric is suitably 20 to 400g/m²The glass cloth of (1). When used for the surface layer, it is 20 to 50g/m²It is preferable that the appearance of the fabric is not impaired and the transparency is maintained.

The amount of glass fiber used is preferably 50% by weight or less of the carbon fiber when rigidity is required and 80% by weight or less when impact resistance is required.

Further, the organic fiber is not brittle as carbon fiber and glass fiber, but rather is tough, and is pliable and resistant to breakage even when bent. Further, since synthetic fibers have a characteristic of being free from electro-corrosion as compared with carbon fibers, they have an advantage of not requiring a countermeasure against electro-corrosion.

Further, organic fibers have an advantage that they can be easily discarded because they can be burned as compared with glass fibers; further, since the specific gravity is about half of that of the glass fiber, there is an advantage that the weight of the member can be reduced extremely.

[ base resin ]

The resin constituting the third aspect of the FRP sheet includes thermosetting resins such as epoxy resins, vinyl ester resins, unsaturated polyester resins, phenol resins, benzoxazine resins, and acrylic resins, and modified resins obtained by modifying these resins.

Among them, epoxy resins, polyester resins, vinyl ester resins, and modified resins thereof, which are excellent in chemical resistance, weather resistance, and the like, are preferable. Phenol resins and benzoxazine resins are excellent in flame retardancy and are preferable for outer sheets requiring heat resistance.

Further, transparent resins such as acrylic resins are preferable in terms of appearance. Among them, acrylic resins are preferable because they are excellent in weather resistance. Furthermore, the weather resistance can be further improved by adding 3 to 20% of an ultraviolet absorber, a solar absorber, and an antioxidant to these transparent resins.

[ resin composition (1) ]

Further, as a preferred matrix resin used in the third aspect, there can be mentioned the epoxy resin composition of the first aspect of the present invention (see the description of the first aspect, and may be hereinafter referred to as resin composition (1)). The materials, conditions, preferable examples, and the like described in the resin composition of the first embodiment are also preferable in the third embodiment as long as there is no particular problem.

When the resin composition (1) is used, curing can be carried out in a short time at a relatively low temperature, so that a prepreg obtained using the epoxy resin composition has a sufficient usable life even when stored at room temperature, and an FRP plate material obtained from the prepreg exhibits excellent mechanical properties. Further, by using the prepreg, the processing time can be shortened in molding the fiber-reinforced composite material, and thus the prepreg can be manufactured at low cost.

(other additives)

In the resin composition (1), the same additives as described in the first embodiment can be used.

(content of sulfur atom in resin composition (1))

The resin composition (1) may have the same sulfur atom content as described in the first embodiment.

(gel time)

The resin composition (1) preferably has the same gel time as in the first embodiment.

(method for producing resin composition (1))

The resin composition (1) can be produced by the same method as in the first embodiment. The preferable conditions in the first aspect are also preferable in the third aspect.

(prepreg)

In the third aspect, the resin composition (1) can be obtained by impregnating the reinforcing fibers with the above-mentioned resin composition (1) as a matrix resin, as in the first aspect. The type, form, and the like of the reinforcing fibers may be the same as those of the first embodiment, and preferred examples are the same.

The form of the reinforcing fibers in the prepreg is not particularly limited, and may be a form in which the reinforcing fibers are aligned in one direction, a form in which the reinforcing fibers are woven, or a nonwoven fabric using chopped reinforcing fibers. In particular, in the case of the aligned form in one direction and the woven form, the conventional compression molding method cannot obtain a fiber-reinforced composite material having a good appearance because the resin flows in the mold after the curing takes time, but if the epoxy resin composition of the present embodiment is used, the epoxy resin composition is cured in a short time, and thus a fiber-reinforced composite material having a good appearance can be obtained.

As described in detail above, the resin composition (1) can be cured in a short time at a relatively low temperature. Therefore, a prepreg obtained using the epoxy resin composition has a sufficient usable life even when stored at room temperature, and a composite material obtained from the prepreg exhibits excellent mechanical properties, and such an effect can be obtained. Further, by using the prepreg, the processing time can be shortened in molding the fiber-reinforced composite material, and thus the prepreg can be manufactured at low cost.

[ resin composition (2) ]

In addition, the matrix resin preferably used in the prepreg of the third embodiment is also preferably used in view of its curing properties, if the thermosetting resin composition of the second embodiment of the present application (see the second embodiment, and may be hereinafter referred to as resin composition (2)) is used. The materials, conditions, preferable examples, and the like described in the resin composition of the second embodiment are also preferable in the third embodiment as long as there is no particular problem.

The thermosetting resin composition is suitable as a matrix resin for a prepreg which can be molded at high speed required for industrial use while maintaining workability at room temperature, long life at room temperature and good physical properties after molding. Furthermore, the prepreg can be molded at a high speed required for industrial use while maintaining workability at room temperature, a long life at room temperature, and good physical properties after molding, and therefore can be molded at a high speed required for industrial use.

Next, the resin composition (2) will be described in detail.

(measurement of viscosity)

The measurement was performed in the same manner as in the second embodiment.

(viscosity at 50 ℃ C. is 5X 10¹～1×10⁴Pa·sec)

The same as in the second embodiment.

(in 120 ℃ atmosphere in 1000 seconds within 1X 10⁶Pa·sec)

The same as in the second embodiment.

(increase in viscosity at 50 ℃ by 2-fold or less after standing at 30 ℃ for 3 weeks)

The same as in the second embodiment.

(composition of resin)

The resin composition described in the second embodiment can be used as well.

(addition of fillers)

The description in the second mode can be used as well.

(prepreg)

The same can be produced as described in the second embodiment. Preferred examples of the amount and material in the second embodiment are also preferred in the third embodiment.

(method of producing FRP)

The FRP can be produced in the third aspect in the same manner as the second aspect. The preferred production conditions, methods, apparatuses, and other examples in the second aspect are also preferred in the third aspect.

The resin composition (2) can provide a thermosetting resin composition suitable as a matrix resin of a prepreg which can be molded at high speed required for industrial use while maintaining workability at room temperature, long life at room temperature and good physical properties after molding.

The prepreg obtained from the resin composition (2) can be molded at high speed required for industrial use while maintaining workability at room temperature, long life at room temperature, and good physical properties after molding. Further, high-speed molding required for industrial use can be performed. The resin composition (2) is very suitable for high-speed molding and is greatly advantageous in reducing molding cost, which is the largest defect of FRP.

[ proportion of matrix resin in prepreg ]

The proportion of the matrix resin in the prepreg is preferably in the range of 20 to 45% by mass. This is because if it exceeds 45%, weight reduction may be sacrificed to make the rigidity and impact resistance of the FRP flat plate similar to those of the metal outer plate.

The reason why the content is 20% or more is because if it is less than 20%, the penetration of the matrix resin becomes difficult, and voids are generated, which may be inferior in physical properties.

The proportion of the matrix resin in the prepreg is 20 to 30%, and when an epoxy resin is used as the matrix resin, sufficient flame retardancy can be obtained without adding a flame retardant to the epoxy resin, and thus it is preferable.

[ surface roughness-center average roughness (Ra) ]

The prepreg of the present embodiment is required to have a center average roughness (Ra) of 0.5 μm or less of the surface of FRP obtained under the above molding conditions, which is required for the reduction of appearance and durability due to the unevenness of the surface of the FRP sheet. The center average roughness (Ra) is more preferably 0.5 μm or less. The unevenness was not eliminated by coating, and was more noticeable. Further, not only the appearance is deteriorated, but also the stress concentration at the tip of the concave portion increases according to the size of the concave portion, and the deterioration progresses, so that the durability of the outer panel can be improved when the unevenness is small.

In this embodiment, the center average roughness (Ra) of the FRP surface is obtained by using a surface roughness measuring instrument 178-: 2.5mm, measurement interval: 2.5 × 5mm, range: 5 μm. Of course, since there are some cases where the FRP surface has irregularities due to damage to the mold surface, the measurement is performed with the exception of such portions in the above-described measurement.

[ Molding method ]

The prepreg of the present embodiment can be cured to obtain an FRP flat sheet, for example, as follows.

A mold having a structure capable of releasing gas from the inside of the mold but capable of suppressing resin release when the mold is closed, and having a surface accuracy of #800 or more, is first adjusted to a temperature equal to or higher than the curing temperature of the thermosetting resin composition, the above-mentioned laminate of the prepreg made of continuous carbon fibers is placed in the mold, and then the mold is closed to fill the entire interior of the mold with the laminate of the prepreg, thereby compression molding.

In addition, as the "structure capable of allowing gas to flow out from the inside of the mold but suppressing resin from flowing out when the mold is closed" included in the mold, a structure called a common edge structure and a rubber seal structure are generally mentioned.

Further, the mold preferably has a structure that allows the inside to be degassed when the mold is closed or while the mold is being closed.

As the deaeration structure, there is a method in which an openable/closable hole is provided in the mold, the hole is opened outside the mold, the hole and a container for deaerating the inside by a pump are communicated through a valve, and the valve is opened when the inside of the mold is closed, and the inside of the mold is deaerated by one gas.

Further, after the completion of the molding of the FRP plate, a mechanism for releasing the FRP plate from the mold, such as a knock-out pin and an air valve, may be attached to the mold to facilitate the removal of the FRP plate. Thus, the FRP sheet can be easily taken out without cooling the mold, and is suitable for mass production. The mechanism for mold release may be a knock-out pin, a gas valve, or any other mechanism known in the art.

With S₁/S₂0.8 to 1 (one-side surface area is S) in the mold₂) A laminate (one-side surface area S) containing the above prepreg made of continuous carbon fibers₁) The matrix resin does not react under pressureExtreme flow and is therefore preferred. The flow of the matrix causes the reinforcing fibers to flow, thereby generating unevenness on the surface of the FRP sheet. The unevenness was not eliminated by coating, and was more noticeable. Further, not only the appearance is deteriorated, but also the stress concentration at the tip of the concave portion increases according to the size of the concave portion, and the deterioration progresses, so that the durability of the outer panel can be improved when the unevenness is small.

The FRP sheet can be obtained by a uniform coating method such as curing, demolding, and further coating with a spray gun. Since the molding shrinkage and thermal shrinkage of the resin during molding also affect the surface quality, an epoxy resin having a small molding shrinkage of the resin and a low-shrinkage resin containing a filler such as talc, glass fine particles, and calcium carbonate are preferable.

The molding temperature is preferably 10 ℃ or higher than the temperature used for the outer panel, and in the case of an automobile outer panel, 90 ℃ or higher, more preferably 110 ℃ or higher, and 130 ℃ or higher is preferable in terms of shortening the molding time.

[ FRP sheet Material ]

The thickness of the FRP sheet varies depending on the application, but in the case of an outer panel of a transportation means such as an automobile running on the ground, it is preferable that the thickness is in the range of 0.5 to 8 mm. If the amount is less than this range, there may be a problem in the penetration resistance; if the content is more than this range, the lightness is insufficient.

In the case of a transport vehicle operating in the air, the speed is faster, and therefore, the range of 1 to 10mm is preferable.

Further, a sandwich structure, a corrugated structure, or a structure in which a frame is provided in a part of the outer plate is also preferable.

In the FRP sheet material of the third aspect, by using continuous carbon fibers as reinforcing fibers, high elastic modulus and strength, which are characteristics of carbon fibers, can be exhibited, and resistance, rigidity feeling, and strength, which are necessary for an outer sheet, can be realized with light weight in response to depressions. Further, since the outer sheet is a continuous fiber, the penetration impact resistance, which is an extremely important characteristic as the outer sheet, can be obtained. That is, the weight reduction, rigidity and impact characteristics which cannot be achieved with short fibers can be obtained. Of course, the deformation resistance, the maximum load, the displacement amount, and the energy absorption are also large.

Furthermore, since the continuous fibers have a woven form, the penetration impact resistance is higher than that of a case where prepregs arranged in one direction are stacked, although the reinforcing fibers are the same amount. The principle is that the fabric is a net-like structure with fibers staggered, so that flying objects can be captured.

Further, the fabric can constitute the outer sheet with a smaller number of sheets than a case where prepregs having the same physical properties in 2 directions orthogonal to one layer (single layer) and arranged in one direction are stacked, and thus can be made lighter. For example, if 2 sheets of prepreg are orthogonally laminated to form an outer sheet, an out-of-plane distortion called a saddle shape occurs due to thermal shrinkage during curing. The out-of-plane deformation is not caused by external force, but is also caused by temperature change. In-plane stress is also generated when the outer panel is subjected to deformation, which causes deformation of the outer panel, and is not preferable from the viewpoint of appearance and aerodynamics.

Further, by using a lightweight, high elastic modulus, and high strength carbon fiber as the reinforcing fiber, the outer panel can be made lightweight and have high mechanical properties, and is also superior in environmental resistance.

[ coating ]

The FRP sheet of the present invention may be surface-coated. The finish is thinner (typically 150 microns or less) and lighter than a gel coat. By coating, not only color but also characteristic are selected in many cases. By selecting an appropriate coating material, it is possible to impart properties or functions which cannot be provided by the FRP sheet material alone, such as gloss or unevenness of the surface, low-temperature and high-temperature environments, water resistance, and ultraviolet resistance, and it is possible to provide the coating material with utility as an outer sheet for the first time.

For example, in the case where the resin portion of the FRP sheet material is a resin weak against ultraviolet rays, ultraviolet ray resistance characteristics as an outer sheet can be imparted by applying a coating superior in ultraviolet ray resistance. Of course, various appearances (makeup) are also possible, and coating is also preferable from the aspect of appearance. The outer panel is required to be colored with other parts for safety, and a subtle color can be formed by coating. Further, since moisture and light are not directly incident on the FRP by coating, a highly durable outer panel having excellent environmental resistance can be obtained. Moreover, the finish is also preferable in terms of fluid resistance.

The coating thickness is preferably 20 to 200 μm. If it exceeds 200. mu.m, the coating film tends to peel off, and is not preferable in terms of mechanical properties and appearance. If the thickness is less than 20 μm, light such as sunlight is directly incident, which causes deterioration and coating unevenness is likely to occur, and this is not preferable from the viewpoint of appearance. Within this range, the FRP outer panel can be formed which is not necessary to increase the weight and is preferable in terms of durability. More preferably 40 to 100 μm.

The coating material can be selected from, for example, synthetic resin coatings such as silicone/epoxy resin coatings, acrylic resin coatings, urethane resin coatings, polyester resin coatings, epoxy resin coatings, fluororesin coatings, urushiol resin coatings, alkyd resin coatings, amino alkyd resin coatings, phenol resin coatings, oil varnishes, nitrocellulose and nitrocellulose lacquers, and water-soluble resin coatings, including primer surfacer, putty, and the like.

The coating materials are roughly classified into one-pack type, two-pack type, and multi-pack type natural drying or room temperature drying coating materials, baking varnishes, ultraviolet curing coating materials, electron beam curing coating materials, and the like. Further, depending on the coating method, the coating composition can be classified into a spray coating composition, a roll coating composition, a flow coating composition, a brush coating composition, and the like.

Further, for selection of the coating material, a coating material composition having good adhesion to the resin of FRP is preferably selected. Further, since FRP is inferior to metal in ultraviolet resistance, a paint excellent in weather resistance is preferable. Specifically, the coating materials referred to as a solar light-blocking coating material and an ultraviolet light-blocking coating material include a coating material obtained by adding an ultraviolet absorber or a reduced telomer polybasic acid to a vehicle of alkyd-acrylic-urethane, a coating material obtained by adding a black pigment such as cobalt oxide, copper oxide, or iron oxide black, an acrylic-urethane-epoxy-silicone coating material, and a fluorine-based coating material. In particular, in the case of clear finishes, the above additives are indispensable.

Further, a conductive coating material in which a conductive filler such as carbon black, graphite, or metal powder is dispersed is preferable. Since a coating material containing a tin oxide or antimony oxide-based conductor can form a transparent conductive coating film, the coating material is a preferable conductive coating material when the appearance of a carbon fiber woven fabric is used or when the antistatic effect is to be provided to prevent dust and dirt from adhering to an outer panel of an automobile or the like due to static electricity.

In addition, it is also effective to apply a luminescent paint (luminous paint) described in JIS K5671 to the entire or a part of an outer panel of a transportation vehicle which is highly required to attract attention at night or the like.

The coating method may be any of known special coating methods, in addition to spray (blow) coating (air gun, airless coating, etc.), electrostatic coating (electrostatic spray coating, spray gun, etc.), electrodeposition coating (cationic, anionic, etc.), powder coating (spray coating, fluidized penetration, electrostatic powder coating, etc.).

Among these, the FRP sheet of the present embodiment is preferably lower in heat resistance than metal because the drying temperature is 120 ℃ or lower and the electrostatic coating using FRP as an anode is superior in coatability. Further, since carbon fibers are conductive, electrostatic coating is also a preferable coating method with high coating material use efficiency.

In addition, when coating is performed to a certain thickness, the surface of the FRP plate is preferably degreased or buffed to remove the release agent. Degreasing or sanding operations may not be required or reduced by using non-silicon based materials as release agents. The temperature of coating is closely related to the heat resistant temperature of the outer panel, and it is preferable to dry the coating at around the heat resistant temperature. In the case of an outer panel for an automobile, the heat-resistant temperature is about 100 ℃, and the drying temperature of the coating is preferably in the range of 60 to 110 ℃. The drying time is about 3 to 60 minutes.

The color of the coating is determined by color matching with other parts, but in the FRP outer panel of the present embodiment using the carbon fiber woven fabric as the reinforcing base material, it is preferable to perform a transparent coating that allows visual observation of the deterioration state and the internal damage state of the FRP portion. Since the panel is transparent, the state of the FRP can be accurately grasped, and there is an effect that a third person who has experienced only the metal outer panel will be given an opportunity to use the FRP outer panel. Of course, a clear finish also has the effect of improving the commercial value by taking advantage of the appearance of the fabric structure. The transparent coating may be the entire outer panel or a part thereof.

The typical clear coating materials include silicone/epoxy based coatings and acrylic based coatings, but they may be urethane based coatings, or mixtures or alloys of these coatings, or they may be colored and transparent.

For the carbon fiber fabric, a fabric having a structure in which the ratio of mass per unit area to thickness is large is suitable. The coating can be carried out by a coating method such as a spray gun to form a uniform and thin coating film. If the coating film is too thin or too thick, the sharpness of the image tends to be lowered, and it is preferable to form the coating film in an appropriate thickness.

[ use of FRP sheet Material ]

The FRP sheet of the present embodiment can be used as inner and outer sheets of transportation means such as motorcycles, automobiles, high-speed vehicles, high-speed boats, bicycles, and aircrafts.

Specifically, the following uses are provided: motorcycle panels such as motorcycle frames, cowlings and fenders, automobile panels such as doors, hoods, back doors, side fenders, side panels, fenders, trunk lids, roofs, side mirror lids, spoilers, diffusers and racks, automobile parts such as engine heads, engine covers and chassis, vehicle exterior panels such as front vehicle heads, roofs, side panels, doors, deck lids and side skirts, vehicle interior equipment such as cargo sheds and seats, wing-shaped inner panels, outer panels, roofs and bottom panels in wing-shaped trucks, gas parts such as air spoilers and side skirts mounted on automobiles or bicycles, aircraft applications such as window frames, cargo sheds, seats, bottom panels, wings, propellers and bodies, housings for notebook computers and cellular phones, medical applications such as X-ray boxes and top panels, and flat speaker panels, Audio products such as speaker cones, sports goods such as golf balls, flower discs, snowboards, water skis, and fenders (rugby, baseball, hockey, and skiing), and general industrial applications such as spiral springs, wind turbine blades, and elevators (frame panels and doors). The sheet material in the present invention includes not only a flat sheet but also a sheet material having a curvature.

Fourth mode

The following describes the fourth embodiment of the present invention in detail, and further describes the description of the sentence, preferred manufacturing conditions, and the like.

The fourth aspect provides an excellent method by which a fiber-reinforced composite molded article having high strength and excellent appearance can be produced in a short time by using a compression molding method.

(Molding Material comprising a thermosetting resin composition impregnated into substantially continuous reinforcing fibers)

The reinforcing fibers described in the third aspect can be used as the reinforcing fibers that can be used in the present aspect, and preferred examples thereof are also preferred in the present aspect.

The thermosetting resin composition used in the fourth embodiment may be any known thermosetting resin that can be used as a matrix resin of FRP, and any of epoxy resin, unsaturated vinyl ester resin, bismaleimide resin, and the like can be suitably used. Among them, if the mechanical properties of the molded article are taken into consideration, an epoxy resin having high mechanical properties after curing and excellent adhesion to the reinforcing fibers can be optimally used.

In this embodiment, instead of the above-described molding material, a molding material in which a material having at least one surface and a short fiber-shaped reinforcing fiber impregnated with a thermosetting resin is superimposed on a material impregnated with a thermosetting resin into which a substantially continuous reinforcing fiber is impregnated may be used. As the thermosetting resin impregnated into the short-fiber reinforcing fibers, those obtained by impregnating reinforcing fibers cut into 12 to 50mm, which are generally called SMC, with the thermosetting resin can be suitably used.

A material obtained by impregnating a thermosetting resin into short-fiber reinforcing fibers has an advantage that FRP is likely to follow a complicated shape having a rib structure or a protrusion structure, as compared with a molding material formed only of substantially continuous reinforcing fibers, because the orientation of the reinforcing fibers is random, but has a disadvantage of poor mechanical properties. Therefore, by superimposing the two components and compression molding, it is possible to obtain FRP having both the advantages of the two components, excellent mechanical properties, and a complicated shape such as a rib structure or a protrusion structure.

Here, as the thermosetting resin in the material in which the thermosetting resin is impregnated into the short fiber-shaped reinforcing fibers, the same resin as that in the material in which the thermosetting resin is impregnated into the substantially continuous reinforcing fibers may be used, or a different resin may be used.

(mold)

In the method for producing FRP of the fourth aspect, it is preferable to use a mold having a structure capable of holding the inside of the mold in an airtight manner when the mold is closed. In this embodiment, the airtightness required for the mold means that the mold is filled with a sufficient amount of the molding material, and the thermosetting resin constituting the molding material does not substantially leak out of the mold when pressurized. As a structure for holding the inside of the mold in an airtight manner, a common edge structure (see fig. 2) or a rubber seal structure may be employed for a portion where the upper mold and the lower mold (the male mold and the female mold) are in contact when the mold is closed. Any known structure may be employed as long as it can hold the inside of the mold in an airtight manner.

Further, although the air remaining in the mold when the mold is closed may cause pinholes on the surface of the FRP and voids in the FRP, if a mold having a deaeration mechanism is used as the mold and the entire interior of the mold is filled with the molding material, the air remaining in the mold can be effectively removed by performing deaeration using the deaeration mechanism.

As the deaeration mechanism, an openable/closable hole (see fig. 3) may be provided in the mold to open the mold to the outside, or a pump may be further provided to reduce the pressure. The degassing is performed by opening the hole at the moment the entire interior of the mold is filled with the molding material and closing it at the time of pressurization.

Further, after the molding of the FRP is completed, a mechanism for releasing the FRP from the mold, such as a knock pin and a gas valve (see fig. 3), may be attached to the mold in order to easily take out the FRP. Thus, the FRP can be easily taken out without cooling the mold, and is suitable for mass production. The mechanism for performing mold release may be a knock-out pin, a gas valve, or any other mechanism known in the art.

(method of producing FRP)

A method for obtaining FRP using the molding material and the mold will be described with reference to the drawings.

Fig. 1A is a view showing a state in which a molding material is placed inside a mold before the mold is closed. In the drawings of the present embodiment, 1 indicates a female mold, 2 indicates a male mold, 3 indicates a common edge structure, 4 indicates an openable and closable hole, 5 indicates a tip (up and down by air), 6 indicates a gasket, a indicates an air inflow when the hole is opened, and B indicates an air inflow when the hole is closed. First, the mold is adjusted to a temperature equal to or higher than the curing temperature of the thermosetting resin of the molding material, and then the molding material is placed inside the mold.

Subsequently, the molding material is pressurized by closing the mold to perform molding. Fig. 1B is a diagram showing a state in which the mold is closed. As shown in the figure, the thermosetting resin hardly flows out of the mold, and the molding material is pressurized to fill the entire interior of the mold.

As described above, the coil bending generated when the prepreg formed of continuous reinforcing fibers is compression-molded is mainly due to the excessive flow of the matrix resin. Therefore, in this embodiment, it was found that a favorable effect can be obtained by using a molding material having a single-side surface area close to the internal single-side surface area (single-side surface area of FRP) when the mold is closed in order to suppress the flow of the resin, and specifically, it is possible to impregnate the thermosetting resin into the substantially continuous reinforcing fibers to form the molding material having the single-side surface area S₁With a single-sided surface area S of the mold interior when the mold is closed₂Ratio of (S)₁/S₂The amount of the metal oxide is 0.8 to 1. If S is₁/S₂If the resin flow rate is less than 0.8, the resin flow inside the mold is vigorous, and the coil is likely to be bent. On the other hand, S₁/S₂If the amount exceeds 1, if the peripheral edge portion of the molding material is exposed from the mold, the mold may be closed or the molding material in the molded article may be insufficient; if the formed material is folded, a disorder of fiber orientation can occur. Here, the one-sided surface area is a surface area of one of substantially equivalent 2 sides having a thickness interval, which constitutes a molded article.

In particular, when high-quality FRP is obtained, a molded product (a shape of the inside of a mold when the mold is closed) having a volume and a height close to those of the molding material can be used. The volume and thickness of the molding material placed in the mold are preferably 100 to 120% of the volume and 100 to 150% of the thickness of the molded product, respectively.

If the volume of the molding material put into the mold is less than 100% of the volume of the molded article, a sufficient pressure cannot be applied to the molding material. On the other hand, if it exceeds 120%, the molding material flows out before airtightness of the mold is obtained, which is not preferable.

If the thickness of the molding material is less than 100% and more than 150% of the thickness of the FRP, it is difficult to uniformly pressurize the entire surface of the molding material, which is not preferable. Here, the thickness of the molding material and the thickness of the FRP are the respective average thicknesses.

In this embodiment, the mold is required to be previously adjusted to a temperature equal to or higher than the curing temperature of the thermosetting resin. In this case, the temperature may be adjusted to a curing temperature determined by the composition of the thermosetting resin or higher, and a more preferable temperature may be selected depending on the molding conditions other than the composition and temperature.

In the method for producing FRP of this embodiment, the pressure at the time of compression molding may be a known pressure at the time of compression molding, and is not particularly limited. The shape of the FRP can be determined as appropriate.

Examples

The following examples specifically illustrate 4 modes of the present invention.

Example of the first mode

In the present example and comparative example, the following materials are used. The average particle diameter is a value measured by a laser diffraction scattering method. In addition, this embodiment is not limited to the following examples.

< epoxy resin >

EP 828: エピコ - ト 828 (registered trademark, bisphenol A epoxy resin, 120p/25 ℃ C.) manufactured by Nippon epoxy resin Ltd

EP 807: エピコ - ト 807 (registered trademark, bisphenol F type epoxy resin, 30p/25 ℃ C.) manufactured by Nippon epoxy resin Ltd

EP 604: エピコ - ト 604 (registered trademark, glycidylamine type epoxy resin) manufactured by Nippon epoxy resin Co., Ltd

N740: EPICLON N-740 (Novolac type epoxy resin, semisolid) manufactured by Dainippon ink chemical industry Co., Ltd

YCDN 701: フエノト - ト YCDN701 (cresol varnish type epoxy resin), manufactured by Tokyo Kagaku K.K.)

フレツプ 50: epoxy resin manufactured by Dongli polysulfide rubber Co., Ltd., registered trademark

EXA 1514: EPICLON EXA1514 bisphenol S type epoxy resin available from Dainippon ink chemical industry Co., Ltd

< amine Compound having at least one Sulfur atom in the molecule >

DDS: セイカキユア -S (diamino diphenyl sulfone, registered trademark, sulfur atom content 12.9 mass%) manufactured by Harong mountain refinement (Kabushiki Kaisha)

BAPS: BAPS (4, 4' -diaminodiphenyl sulfide, sulfur atom content 7.4 mass%) prepared by refining Songshan

BAPS-M: BAPS-M (bis (4- (3-aminophenoxy) benzene) sulfone prepared by Harmony mountain refinement (strain) and having a sulfur atom content of 7.4 mass%)

ASD: ASD (4, 4' -diaminodiphenyl sulfide, sulfur atom content 14.8 mass%) prepared from Harmony mountain refinement (strain)

TSN: TSN (O-tolidine sulfone, sulfur atom content: 11.7% by mass) manufactured by Harmony mountain refinement

< Urea Compound >

PDMU: phenyl dimethyl urea (average particle size 50 μm)

DCMU: 3, 4-dichlorophenyl-N, N-dimethylurea (average particle size 50 μm)

< dicyandiamide >

DICY 7: dicyandiamide (average particle diameter of 7 μm)

DICY 15: dicyandiamide (average particle diameter of 15 μm)

DICY 1400: dicyandiamide (average particle diameter of 20 μm)

< additives >

PVF: チツソ manufactured ビニレツク E (polyethylene formal)

YP 50: フエノト - ト YP50 manufactured by Tokyo Kabushiki Kaisha

Fumed silica: アエロジル 300 manufactured by Nippon Kogyo アエロジル K.K.)

(evaluation method)

A prepreg was produced by the method described later using the resin composition of the present embodiment, and the gel time, pot life, and mechanical properties thereof were measured. The measurement method is as follows.

(1) Gel time

A square sample of 2mm side length was cut out from the prepreg and sandwiched by 2 glass cover sheets. It was placed on a hot plate controlled to 130 ℃. + -. 0.5 ℃. The initiation time was determined as the gel time immediately after the sample was placed. The prepreg is repeatedly pressed with tweezers or the like from time to confirm the state of the epoxy resin composition, and the time for complete gelation is measured and taken as the gel time. The complete gelation referred to herein means a state in which the epoxy resin composition does not flow when pressed with tweezers or the like.

(2) Period of use

The prepreg was placed in a constant temperature dryer at 30. + -. 1 ℃ and the adhesion of the prepreg was observed every day up to 21 days, and the number of days in which the adhesion was lost (the prepregs were not adhered to each other) was defined as the usable period.

(3) Mechanical Properties

The prepreg was molded by vacuum bag molding to prepare a flat plate-like fiber-reinforced composite material having a length of 200mm, a width of 200mm and a thickness of 150 mm. The 0 ° flexural strength and 90 ° flexural strength of the flat sheet were measured according to ASTM D790.

(content of sulfur atom)

When the component A does not have a sulfur atom, the sulfur atom content S can be determined by the following equation, where the sum of the parts by mass of the components A, C, D and additives added is X, the part by mass of the component B-1 used in the production of the epoxy resin composition is Y, and the sulfur atom content in the component B-1 used in the production of the epoxy resin composition is p (% by mass).

S (mass%) ═ pY/(X + Y)

When the component a has a sulfur atom, the measurement is performed directly from the epoxy resin composition by the following atomic absorption spectrometry. That is, after the production of the epoxy resin composition, 50mg of the epoxy resin composition was decomposed in an aqueous nitric acid solution, and the solution was diluted with ion-exchanged water to 50ml, and the aqueous solution was used as a measurement sample.

The sulfur atom concentration of the measurement sample was measured by atomic absorption spectrometry using a high-frequency plasma emission spectrometer (ICAP-575 MK-II, manufactured by Nippon Kogyo corporation, ジヤ - レル and アツシユ) (measurement conditions: 0.8L/min of plasma gas, 16L/min of cooling medium gas, 0.48L/min of carrier gas, and 180.7nm of measurement wavelength). The concentration of sulfur atoms in the aqueous solution was determined using a calibration curve prepared in advance, and the sulfur atom content (% by mass) in the epoxy resin composition was calculated from the concentration of sulfur atoms.

Examples 1 to 10

The epoxy resin compositions were mixed in the composition ratios shown in Table 1 until uniform. The mass per unit area of the resin was 33.7g/m using a simple roll coater²The epoxy resin composition is uniformly coated on a release paper to form a resin layer. The resin layer was attached to a fiber basis weight of 125g/m²The two surfaces of a sheet-like body made of carbon fibers (TR50S, tensile modulus: 240GPa) made by Mitsubishi Yang corporation were pulled in one direction, and then heated and pressed at 100 ℃ and a linear pressure of 2kg/cm with a roller to impregnate the carbon fibers with the epoxy resin composition, thereby obtaining a fiber mass per unit area of 125g/m²(resin content: 35% by mass).

The prepregs obtained from the epoxy resin compositions of examples 1 to 10 were evaluated for gel time and usable life at 130 ℃, and as a result, both gel time and usable life were 200 seconds or less, and adhesiveness was maintained even when 21 days passed during usable life, and usable life of 21 days or more was confirmed.

The physical properties of the flat composite material (physical properties of the FRP sheet) were also such that the 0 DEG flexural strength was more than 160kg/mm²The 90-degree bending strength exceeds 10kg/mm²Thus, the composition shows excellent physical properties.

Examples 11 to 20

Prepregs were produced in the same manner as in example 1 except that the components were mixed in the composition ratios shown in table 2 until uniform, and evaluated.

The prepregs obtained from the epoxy resin compositions of examples 11 to 20 were all confirmed to have a gel time of 200 seconds or less and a usable period of 21 days or longer.

The physical properties of the flat composite material (physical properties of the FRP sheet) were also such that the 0 DEG flexural strength was more than 160kg/mm²The 90-degree bending strength exceeds 10kg/mm²Thus, the composition shows excellent physical properties.

Example 21

In the composition shown in example 21 in Table 3, the epoxy resin of the component B and the amine component (DDS) were mixed at room temperature, and then heated at 150 ℃ to partially react them, thereby preparing a mixture having a viscosity of 30 to 90 poise (component B-2) at 90 ℃. The reaction product, component A and component C, D were mixed in a composition ratio shown in example 21 of Table 3 until uniform to prepare an epoxy resin composition. The mass per unit area of the resin was 33.7g/m using a simple roll coater²The epoxy resin composition is uniformly coated on a release paper to form a resin layer. The resin layer was attached to a fiber basis weight of 125g/m²The method (2) comprises aligning both surfaces of a sheet-like body made of carbon fibers (TR50S, tensile modulus: 240GPa) made by Mitsubishi Yang, in one direction, and heating and pressing the sheet-like body with a roller at 100 ℃ and a linear pressure of 2kg/cm to form an epoxy resinThe fat composition is impregnated into the carbon fiber to obtain a fiber having a mass per unit area of 125g/m²(resin content: 35% by mass).

As a result of evaluating the gel time and usable period at 130 ℃ of the prepreg obtained from the epoxy resin composition of example 21, the gel time was 200 seconds or less, and the adhesiveness was maintained even when 21 days passed during the usable period, and therefore, a usable period of 21 days or more was confirmed.

The physical properties of the flat composite material (physical properties of the FRP sheet) were also such that the 0 DEG flexural strength was more than 160kg/mm²The 90-degree bending strength exceeds 10kg/mm²Thus, the composition shows excellent physical properties.

Examples 22 to 31

The epoxy resin and amine component (DDS) of component A were mixed at room temperature in the composition ratios shown in Table 3, and then heated at 150 ℃ to partially react them, thereby preparing a mixture having a viscosity of 30 to 90 poise at 90 ℃. A prepreg was produced and evaluated in the same manner as in example 21, except that the reactant was mixed with the components B and C in the composition ratio shown in table 3 until the mixture was uniform.

The prepregs obtained from the epoxy resin compositions of examples 22 to 31 were all confirmed to have a gel time of 200 seconds or less and a usable period of 21 days or more.

The physical properties of the flat composite material (physical properties of the FRP sheet) were also such that the 0 DEG flexural strength was more than 160kg/mm²The 90-degree bending strength exceeds 10kg/mm²Thus, the composition shows excellent physical properties.

Examples 32 to 45

The epoxy resin and the amine component as the component A were mixed at room temperature in the composition ratios shown in Table 4, and then partially reacted by heating at 150 ℃ to prepare a mixture having a viscosity of 30 to 90 poise at 90 ℃. A prepreg was produced and evaluated in the same manner as in example 21, except that the reactant was mixed with the components B and C in the composition ratio shown in table 4 until the mixture was uniform.

The prepregs obtained from the epoxy resin compositions of examples 32 to 45 were all confirmed to have a gel time of 200 seconds or less and a usable period of 21 days or more.

Comparative examples 1 to 8

Prepregs were produced in the same manner as in example 1 except that the components were mixed in the composition ratios shown in table 5 until uniform, and evaluated.

As a result, the gel time exceeded 200 seconds or curing did not complete within several hours, except for comparative examples 2, 4 and 6. Comparative examples 2, 4 and 6 showed rapid curability with a gel time of 200 seconds or less, but the pot life was short, and was 5 days or less.

Comparative examples 9 to 10

Prepregs were produced and evaluated in the same manner as in example 21, except that the components were mixed in the composition ratios shown in table 3 until uniform.

As a result, in comparative examples 9 and 10 containing no dicyandiamide, the same amount as in examples 21 and 24 was added as the total amount of the curing agent, but only flat composite materials having a 0 ° flexural strength lower by about 10% than that of the flat composite materials produced in each example could be obtained. Further, in comparative example 10, the usable period was as short as 5 days or less.

As described in detail above, the epoxy resin composition of the present embodiment can be cured in a short time at a relatively low temperature. Therefore, a prepreg obtained using the epoxy resin composition can be obtained which has a sufficient usable life even when stored at room temperature, and a composite material obtained from the prepreg exhibits excellent mechanical properties. Further, it was confirmed that the use of the prepreg can shorten the processing time in the molding of the fiber-reinforced composite material, and thus can be produced at low cost.

TABLE 1

Composition (I)		Name of resin	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7	Example 8	Example 9	Example 10	Example 44	Example 45
															Component A (parts by mass)	Epoxy resin	EP828	86	84	82	78	68							33
EP807						86	68	34	70	61
													N740													43
フレツプ50											30
													EXA1514														40

Component B (parts by mass)	Amine compound having sulfur atom	DDS		2	4	6	10	20	2	20	54	20	20	10	10
																BAPS
		BAPS-M
															ASD
		TSN
															C component (parts by mass)	Urea compounds	PDMU	5	5	5	5	5
DCMU						5	5	5	3	12	10	10
													Component D (parts by mass)	Dicyandiamide			DICY1400									7	7
DICY15						7	7	7
															DICY7	7	7	7	7	7						7	7
Additive (quality)		ビニレツクE
													YP50
		アエロジル 300
													Sulfur atom content (%)			0.26	0.52	0.77	1.29	2.58	0.26	2.58	6.98	2.58	2.58			6.5	6.1
Gel time (S)			190	170	160	155	150	190	155	130	170	160														190	190
													Time of use		Sky	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21			＞21	＞21
Mechanical Properties		0 degree bend test (Kg/mm)	168	173	175	170	172	171	164	163	170	175														167	170
													90 degree bend test (Kg/mm)	12.6	12.4	12.4	12.3	13.9	13.1	13.7	13.5	14.5	14.5	13.5	14.0

TABLE 2

Composition (I)		Name of resin	Example 11	Example 12	Example 13	Example 14	Example 15	Example 16	Example 17	Example 18	Example 19	Example 20
													Component A	Epoxy resin	EP828					77	77	77	77	77
EP807	58
											N740				70
YCDN701			70
											EP604						70						54
Component B	Amine compound having sulfur atom	DDS	20				10																		30
											BAPS		20	20	20		10
		BAPS-M							10
											ASD								10
		TSN																				10
											Component C	Urea compounds	PDMU		5	5	5								5
DCMU	15				5	5	5	5	5
													Component D	Dicyandiamide	DICY1400	7
DICY15		5	5	5	5	5
											DICY7									5	5	5	5
Additive agent		ビニレッE						3	3	3																3
											YP50								3	3
		ァェロジル300																					3
											Sulfur atom content (%)			2.58	1.48	1.48	1.48	1.29	1.29	1.29	1.48			1.17	3.87
Gel time (S)			155	180	170	155	165	170	176	175												180	160
											Time of use		Sky	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21			＞21	＞21
Mechanical Properties		0 degree bend test (Kg/mm)	168	166	164	164	168	171	165	167												166	172
											90 degree bend test (Kg/mm)	12.4	12.1	12.5	12.4	12.5	12.7	12.5	12.2	12.3	12.9

TABLE 3

Composition (I)		Name of resin	Example 21	Example 22	Example 23	Example 24	Example 25	Example 26	Example 27	Example 28	Example 29	Example 30	Example 31	Comparative example 9	Comparative example 10
																Component A	Epoxy resin	EP828	5	5	5	5	5							5
EP807						5	5	5	5	5	5		5
														N740
YCDN701
														EP604
Component B-2	Amine compound having sulfur atom in epoxy resin	EP828	81	79	77	73	63																							77
														EP807						81	63	29	65	56	53		56
		N740
														YCDN701
		EP604
														DDS
			2	4	6	10	20	2	20	54	20	20	20		6	20
														BAPS
		BAPS-M
														ASD
		TSN
Component C	Urea compounds													PDMU			5	5	5	5	5							5
		DCMU						5	5	5	3	12	15			12
														Component D			Dicyandiamide	DICY1400									7	7	7
DICY15						7	7	7
															DICY7	7		7	7	7	7

Additive agent		ビニレックE
																YP50
		ァェロシル300
																Evaluation results
Sulfur atom content (%)			0.26	0.52	0.77	1.29	2.58	0.26	2.58	6.98	2.58	2.58	2.58	0.77	2.58
																Gel time (S)			185	165	150	150	140	180	145	100	145	150	145	230	225
Time of use		Sky	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	4
																Mechanical Properties		0 degree bend test (Kg/mm)	175	172	172	169	168	171	166	168	174	168	169	150	155
90 degree bend test (Kg/mm)	13.1	12.9	12.3	12.5	12.7	12.6	12.4	12.4	12.9	13.2	12.5	10.0	10.0

TABLE 4

Composition (I)		Name of resin	Example 32	Example 33	Example 34	Example 35	Example 36	Example 37	Example 38	Example 39	Example 40	EXAMPLE 41	Example 42	Example 43
															Component A	Epoxy resin	EP828				5	5	5	5	5		5	5	5
EP807
													N740	5
YCDN701		5
													EP604					5						5
Component B-2	Amine compound having sulfur atom in epoxy resin	EP828				72	72	72	72	72		75																68	63
													EP807	65
		N740		65
													YCDN701			65
		EP604									49
													DDS				10					30	10	10	10
		BAPS	20	20	20		10
													BAPS-M						10
		ASD							10
													TSN								10
		Component C	Urea compounds	PDMU	5	5	5																			5	3	10	15
DCMU															5	5	5	5	5
				Component D	Dicyandiamide	DICY1400
DICY15	5	5	5										5	5
						DICY7						5										5	5	5	7	7	7
Additive agent		ビニレックE														3	3	3			3
				YP50							3	3
		ァェロジル300																		3

Sulfur atom content (%)			2.58	2.58	2.58	1.29	1.29	1.29	1.29	1.29	2.58	1.29	1.29	1.29
															Gel time (S)			170	160	145	160	160	170	175	175	150	180	160	140
Time of use		Sky	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21	＞21
															Mechanical Properties		0 degree bend test (Kg/mm)	164	172	175	170	172	164	169	168	177	172	175	173
90 degree bend test (Kg/mm)	12.2	12.4	12.3	11.9	12.6	12.4	12.3	12.7	12.0	13.1	12.8	12.9

TABLE 5

Composition (I)		Name of resin	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Comparative example 5	Comparative example 6	Comparative example 7	Comparative example 8
											Component A	Epoxy resin	EP828	87	33					75	70
EP807			72.1	57	72.1	57
									Component B-1	Amine compound having sulfur atom			DDS	1	55	20	20			20	20
BAPS
											BAPS-M
ASD					20	20
											TSN
Component C	Urea compounds	PDMU	5	5	0.9	16
									DCMU					0.9	16	5	10
									Component D	Dicyandiamide	DICY1400	7	7	7	7
DICY15					7	7
											DICY7
Sulfur atom content (%)			0.13	7.10	2.58	2.58	2.96	2.96												2.58	2.58
									Gel time(s)			250	170	-	160	-	160	250	250
Time of use		Sky	＞21	5	＞21	4	＞21	4												＞21	＞21
									Mechanical Properties		0 degree bend test (Kg/mm)	155	173	168	159	169	161	164	163
90 degree bend test (Kg/mm)	12.0	12.3	12.4	12.3	12.2	13.1	13.7	13.5

The "-" in the column of gel time indicates that the epoxy resin did not gel.

Example of the second mode

Hereinafter, a second embodiment of the present invention will be described in detail based on examples. In addition, this embodiment is not limited to the following examples.

The following epoxy resin and curing agent were prepared as raw materials for the thermosetting resin composition.

< epoxy resin >

EP828：

Liquid bisphenol A type epoxy resin manufactured by Nippon epoxy resin Co., Ltd., エピコ - ト 828 (registered trademark)

EP1009：

Solid bisphenol A type epoxy resin manufactured by Nippon epoxy resin Co., Ltd., エピコ - ト 1009 (registered trademark)

AER4152：

Asahi Kasei Co., Ltd, epoxy resin アラルダイト AER4152 (registered trademark)

N740：

Novolac type epoxy resin manufactured by Dainippon ink chemical Co., Ltd., エピクロン N-740 (registered trademark)

< curing agent >

HX3722：

Microcapsule type latent curing agent manufactured by Asahi Kasei corporation, ノバキユア HX3722 (registered trademark)

FXE1000：

Latent curing agent for epoxy resin manufactured by Fuji Kabushiki Kaisha フジキユア FXE1000

PDMU：

PTI Benzyldimethylurea manufactured by Japan K. オミキユア 94 (registered trademark)

DCMU：

Baotai ケ Guo chemical Co., Ltd, 3, 4-dichlorophenyl-N, N-dimethylurea, DCMU99

Dicy：

Dicyandiamide, Dicy7, manufactured by Nippon epoxy resin Co

2P4MZ：

2-phenyl-4-methylimidazole manufactured by four kingdoms chemical industry Co., Ltd

< measurement of viscosity >

The device comprises the following steps: RDS-200 manufactured by Rheometrics

Measurement mode: parallel plates (25mm phi, 0.5mm apart)

Frequency: 1Hz

Temperature setting: heating at 50 deg.C and 10 deg.C/min to 120 deg.C, and measuring isothermal viscosity

Measurement data: viscosity at 50 deg.C, cut-off viscosity of more than 10 after 120 deg.C²Time of Pa · sec. In this example, it was confirmed that the viscosity of all the thermosetting resin compositions was 10 or less at 120 ℃¹Pa·sec。

< thickening after 30 ℃ C.. times.3 weeks >

Immediately after preparing the thermosetting resin composition, a sample was taken, and the viscosity at 50 ℃ eta was measured by the above-mentioned viscometry₀The same thermosetting resin composition was placed in a 30 ℃ dryer for 3 weeks, subjected to a heat history, and then similarly conductedViscosity determination, determining the viscosity eta at 50 ℃₁. Viscosity increase by eta₁/η₀And (4) obtaining.

< preparation of prepreg >

The thermosetting resin composition was heated to 50 ℃ to reduce the viscosity, and a hot-melt film was prepared by thinly coating the composition on release paper, and the hot-melt film was impregnated with a carbon fiber woven fabric TR3110 made by Mitsubishi Yangyo to obtain a prepreg. The resin content was adjusted to 30 mass%.

< Forming >

11 layers of prepregs were stacked in the same direction, and molded by a hot press at a molding pressure of 2MPa using a metal mold having a common edge. The thickness of the formed plate is approximately 2 mm.

< measurement of mechanical Properties >

An interlaminar shear test (ILSS) was performed according to ASTM D790 on a bending test using a universal tester manufactured by Instron corporation according to ASTM D2344.

Examples 46 to 50

Thermosetting resin compositions were prepared in the compositions shown in Table 6, and the viscosity at 50 ℃ after 30 ℃ X3 weeks were measured. Measuring the viscosity of the mixture after reaching 120 ℃ until the viscosity exceeds 10²Time of Pa · sec. The prepreg thus produced was evaluated for handleability by hand. The one having proper tackiness and drapability and easy handling was marked as "O" and the one having difficulty in handling was marked as "X". The prepared prepreg was left at 30 ℃ for 3 weeks, and similarly evaluated for subsequent workability. Further, a prepreg was formed by the above method. The molding was carried out under 3 conditions of 120 ℃ X15 minutes, 120 ℃ X10 minutes, and 140 ℃ X4 minutes, and the mechanical properties were measured. The results are summarized in Table 6. The thermosetting resin compositions shown in the examples were excellent in the workability of the prepreg immediately after the preparation and the workability of the prepreg after 3 weeks at 30 ℃. The surface appearance after molding was also beautiful and the mechanical properties were also good.

Comparative example 13 (example of Low viscosity at 50 ℃ C.)

Thermosetting resin compositions were prepared in the compositions shown in Table 7. Due to viscosity at 50 ℃ of less than 5X 10¹Pa · sec, the prepreg immediately after preparation is very viscous, sticky and difficult to handle.

Comparative example 14 (example of high viscosity at 50 ℃ C.)

Thermosetting resin compositions were prepared in the compositions shown in Table 7. Due to a viscosity at 50 ℃ of more than 1X 10⁴Pa sec, the thermosetting resin composition is very hard and cannot be made into a thin film.

Comparative example 15 (example of thickening viscosity at 30 ℃ C. for 3 weeks by more than 2 times)

Thermosetting resin compositions were prepared in the compositions shown in Table 7. The thermosetting resin composition after 30 ℃ C.. times.3 weeks was very hard and the viscosity could not be measured. The prepreg immediately after preparation had good handleability, but it was hardened after being left at room temperature for 3 weeks, and the life was completed.

Comparative example 16 (10 at 120 ℃ C.)⁶Pa sec arrival time over 1000 seconds example)

Thermosetting resin compositions were prepared in the compositions shown in Table 7. 10 at 120 ℃⁶The Pa · sec arrival time was 1300 seconds, and it was clearly found that the curability was inferior to that of the examples. In addition, the bending test was judged as "not measurable" because no fracture occurred.

As described above, the thermosetting resin composition of the present embodiment can provide a thermosetting resin composition suitable for a matrix resin of a prepreg which is excellent in handleability at room temperature and long-life at room temperature, maintains excellent physical properties after molding, and can be molded at high speed required for industrial use.

As described above, the prepreg of the present embodiment is excellent in handleability at room temperature and long life at room temperature, and can be molded at high speed required for industrial use while maintaining good physical properties after molding.

As is evident from the above, the thermosetting resin composition, prepreg, and FRP production method of the present embodiment are all very suitable for high-speed molding, and are greatly advantageous for reducing the molding cost, which is the largest defect of FRP.

TABLE 6

			Example 46	Example 47	Example 48	Example 49	Example 50
								Composition of	EP828	Portions are	40	40	60	60	60
EP1009	Portions are	20	20	20	20	20
							AER4152		Portions are			20	20	20
N740	Portions are	40	40
							FXE1000		Portions are	5
HX3722	Portions are				5	10
							Dicy		Portions are	5	5	5	5	5
DCMU	Portions are		15
							PDMU		Portions are	5		10	5	5
Viscosity at 50 deg.C		Pa·sec	350	380	280	260									230
							Handleability of prepreg immediately after preparation		○/×	○	○	○	○	○
Thickening at 30 ℃ for 3 weeks		Multiple times	1.5	1.7	1.4	1.4									1.5
							Workability of prepreg after 3 weeks of preparation		○/×	○	○	○	○	○
10 at 120 ℃6Pa·sec time of arrival		Second of	530	950	900	780									520
							Bending Strength at 120 ℃ for 15 minutes		MPa	1200	1100	1100	1200	1200
Same ILSS		MPa	74	72	73	73									73
							Bending Strength at 120 ℃ for 10 min Molding		MPa	1100	770	820	950	1200
Same ILSS		MPa	74	65	68	70									74
							Bending Strength at 140 ℃ for 5 minutes Forming		MPa	1200	1200	1200	1200	1200
Same ILSS		MPa	75	73	74	72									74

TABLE 7

			Comparative example 13	Comparative example 14	Comparative example 15	Comparative example 16
							Composition of	EP828	Portions are	50	30	40	60
EP1009	Portions are	10	40	20	20
						AER4152		Portions are				20
N740	Portions are	40	30	40
						FXE1000		Portions are	5	5
Dicy	Portions are	5	5	5
						PDMU		Portions are	5	5		7
2P4MZ	Portions are			5
						Viscosity at 50 deg.C		Pa·sec	45	15000	340	270
Handleability of prepreg immediately after preparation		○/×	×		○								○
						Thickening at 30 ℃ for 3 weeks		Multiple times	1.3		∞	1.4
Workability of prepreg after 3 weeks of preparation		○/×	○		×								○
						10 at 120 ℃6Pa sec arrival time		Second of	620		960	1300
Bending Strength at 120 ℃ for 15 minutes		MPa	1200		1100								Can not measure
						Same ILSS		MPa	73		72	35
Bending Strength at 120 ℃ for 10 min Molding		MPa	1200		780								Can not measure
						Same ILSS		MPa	72		66	22
Bending Strength at 140 ℃ for 5 minutes Forming		MPa	1100		1200								Can not measure
						Same ILSS		MPa	74		73	42

Example of the third mode

The third embodiment of the present invention will be specifically described below with reference to examples. In addition, this embodiment is not limited to the following examples.

[ examples based on resin composition (1) ]

Examples 1 to 20 shown in the first embodiment satisfy the conditions required in the present embodiment. Examples 1 to 20 showed excellent results as described in the examples of the first embodiment, thereby demonstrating that the epoxy resin composition and the prepreg provided by the present embodiment have excellent characteristics. In addition, comparative examples 1 to 8 shown in the first embodiment do not satisfy the conditions required in the present embodiment. This proves that none of comparative examples 1 to 8 can exhibit the excellent characteristics as in examples 1 to 20.

Example 51

The mass per unit area of the resin was 26.8g/m using a simple roll coater²The epoxy resin composition obtained in example 3 of the first embodiment was uniformly coated on a release paper to form a resin layer. The resin layer was bonded to a fiber basis weight of 125g/m²The two surfaces of a sheet-like body made of carbon fibers (TR50S, tensile modulus: 240GPa) made by Mitsubishi Yang corporation were pulled in one direction, and then heated and pressed at 100 ℃ and a linear pressure of 2kg/cm with a roller to impregnate the carbon fibers with the epoxy resin composition, thereby obtaining a fiber mass per unit area of 125g/m²(resin content: 30% by mass).

On the other hand, the mass per unit area of the resin was 164g/m by a simple roll coater²The epoxy resin composition obtained in example 3 was uniformly coated on a release paper to form a resin layer. The resin layer was bonded to a carbon fiber woven fabric TR3110 (woven fabric TR30S3L (number of filaments 3000) made by Mitsubishi Yang corporation) having a weaving density of 12.5 filaments/inch²) One side of the epoxy resin composition was then heated and pressed at 100 ℃ and a linear pressure of 2kg/cm with a roller to impregnate the epoxy resin composition into the carbon fiber to obtain a fiber having a mass per unit area of 200g/m²(resin content: 45 mass%) was used.

A prepreg and a fabric prepreg were cut into 200X 200mm, 16 sheets of the prepreg were laminated in a fiber direction of 0 °/90 °/0 °/90 °/0 °/90 °/0 °/90 °/0 °/90 °/0 °/90 °/0 °/90 °, and 1 sheet of the fabric prepreg was laminated on the laminated sheet (on the 0 ° layer) to prepare a prepreg laminate.

A220X 220mm metal mold (210X 210mm metal mold surface which can be used) having a gasket made of butyl rubber having a width of 10mm and a thickness of 3mm placed in an L-shape on 2 sides out of 4 sides was heated to 130 ℃.

The prepreg previously prepared was placed at the usable portion of the metal mold at a distance of 5mm from the end of the metal mold or the butyl rubber gasket, respectivelyA laminate. And, the metal mold was immediately closed and applied for 15 minutes at 10kg/cm²The FRP plate is obtained.

3 test pieces of 30X 30mm were arbitrarily cut out from the FRP sheet material, and the volume content of the carbon fiber (Archimedes method) was determined, and the average volume content was 60.6%. The resin content was calculated to be 30.9 wt% using a density of 1.25 for the matrix resin and an average density of 1.82 for the carbon fibers.

The resulting FRP plate was observed with irregularities due to damage to the surface of the mold, and the center line average roughness of the portion having no irregularities was measured by the apparatus and method described in the detailed description, and was 0.27 μm.

As described above, according to the present embodiment, it is possible to provide an FRP panel suitable as an outer panel for transportation means and industrial machinery and a prepreg suitable for obtaining an FRP panel.

Example of the fourth mode

The fourth embodiment of the present invention will be specifically described below with reference to examples. In addition, this embodiment is not limited to the following examples.

Example 52

As a structure for holding the inside of the mold in an airtight manner, a common edge structure was adopted for a portion where the upper mold and the lower mold were in contact when the mold was closed (see FIG. 2), and the surface area of the portion excluding the thickness of the FRP portion of the lower mold was 900cm²The upper die and the lower die are heated to 140 ℃ simultaneously.

As a molding material, a prepreg TR390E125S (manufactured by Mitsubishi Yang corporation) in which carbon fibers aligned in one direction were impregnated with an epoxy resin composition was cut into 285X 285mm pieces, and 18 pieces (2 mm in thickness and 162cm in total volume) were laminated so that the orientation directions of the fibers were staggered between 0 ℃ and 90 °³The surface area of the single face is 812cm²) And the resulting material. S₁/S₂812/900 ═ 0.9. The epoxy resin used in the prepreg TR390E125S was as followsAn epoxy resin composition produced by the production method, which corresponds to the epoxy resin composition of the first embodiment.

That is, to 100 parts by mass of a resin composition obtained by reacting a mixture (mass ratio of 92: 8) of EP828 and DDS at 150 ℃, 15 parts by mass of EP828, 6 parts by mass of PDMU, and 9 parts by mass of dicyandiamide were added and mixed to obtain a uniform epoxy resin composition.

The molding material was placed on the lower mold, and the upper mold was immediately set down to close the mold, and applied for 10 minutes at 9.8X 10²After the pressure of KPa, the mold was opened, the temperature of the mold was maintained at 140 ℃ and the molded article (thickness: 1.6mm, volume: 144 cm) was taken out through the ejector pin attached to the mold³). The molded article had no pinholes or voids on the surface, back surface and cross section, and was excellent in appearance.

Example 53

As the molding material, the molding material used in example 1 and an epoxy resin SMC Lytex4149 (manufactured by QUANTUM COMPOSITES) containing carbon fibers (except that the surface area of one side of the thickness portion was 812 cm)²) The adhered molding material (total thickness of 4mm, total volume of 325 cm)³)。S₁/S₂Is 0.9.

The molding material was placed on the lower mold, and the upper mold was immediately set down to close the mold, and the molding material was applied for 10 minutes at 3.0X 10³After the pressure of kPa, the mold was opened, the temperature of the mold was maintained at 140 ℃ and the molded article (thickness: 3.2mm, volume: 288 cm) was taken out through the ejector pin attached to the mold³). The molded article was of a grade free from problems in appearance and physical properties.

As described above, it was confirmed that by using the method for producing FRP of the present embodiment and using the compression molding method suitable for mass production, FRP formed of substantially continuous reinforcing fibers having high strength and excellent appearance can be obtained.

Comparative example 17

In addition to asThe molding material used was a prepreg (TR 390E125S, manufactured by Mitsubishi corporation) prepared by cutting carbon fibers aligned in one direction into pieces of 250X 250mm and stacking 24 pieces (2.6 mm in thickness and 162cm in total volume) so that the alignment directions of the fibers were staggered between 0 DEG and 90 DEG, the prepreg being prepared by impregnating the carbon fibers with an epoxy resin composition³The surface area of one side of the sheet was 625cm²) Molding was carried out under the same conditions as in example 1 except for the obtained material. S₁/S₂625/900 ═ 0.7.

The molded article has a significant disorder in fiber orientation, particularly in the outer peripheral portion, due to the flow of resin during molding.

Comparative example 18

Except that a prepreg TR390E125S (manufactured by Mitsubishi Yang corporation) in which carbon fibers aligned in one direction were impregnated with an epoxy resin composition was cut into 320X 320mm as a molding material, and 14 sheets (1.6 mm in thickness and 162cm in total volume) were laminated so that the fiber orientation directions were staggered at 0 ℃ and 90 °³The surface area of one side is 1024cm²) Molding was carried out under the same conditions as in example 1 except for the obtained material. S₁/S₂1024/900-1.1.

In the molding, since the reinforcing fibers constituting the molding material are exposed from the mold, the fibers are pulled out, and disorder of fiber orientation occurs. Therefore, the molded article obtained had poor appearance and a smooth surface could not be obtained.

Possibility of industrial utilization

The present invention can easily provide a prepreg and a lightweight, high-strength and high-rigidity FRP, which are provided with a quantitative index, can be cured in a short time at a relatively low temperature, have excellent mechanical properties, and can be stored at room temperature for a long time. It is widely applicable from sports and leisure applications to industrial applications such as automobiles and aircrafts.

Claims (10)

1. A prepreg is prepared by molding at a pressure of 10kg/cm or more²And a prepreg obtained by impregnating reinforcing fibers with a resin composition as a matrix resin, wherein the reinforcing fibers are woven carbon fibers and the ratio W/t of the mass W per unit area to the thickness t of the woven carbon fibers is in the range of 700 to 1700, wherein the unit of W is g/m²T is mm, and the coverage factor of the carbon fiber fabric is 90 toWithin 100%; wherein the resin composition is:

an epoxy resin composition comprising the following components A, B, C and D, wherein the contents of the sulfur atom and the C in the epoxy resin composition are 0.2 to 7% by mass and 1 to 15% by mass, respectively,

component A: an epoxy resin, and a curing agent,

and B component: a component B-1 which is an amine compound having at least one sulfur atom in the molecule and/or a component B-2 which is a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in the molecule,

and C, component C: a urea compound which is a compound of urea,

and (D) component: dicyandiamide;

or,

an epoxy resin composition comprising a component B-2, a component C and a component D, wherein the content of the sulfur atom and the content of the component C in the epoxy resin composition are 0.2 to 7% by mass and 1 to 15% by mass, respectively,

b-2 component: a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in the molecule,

and C, component C: a urea compound which is a compound of urea,

and (D) component: dicyandiamide.

2. The prepreg according to claim 1, wherein the forming temperature is 120 ℃ or higher.

3. The prepreg according to claim 1 or 2, wherein the resin content is 33% or less.

4. A fiber reinforced composite material plate is prepared by using a prepreg under a forming pressure of 10kg/cm or more²And a fiber-reinforced composite plate material obtained by heat curing for 15 minutes or less, wherein the surface of the fiber-reinforced composite plate material has a center average roughness Ra of 0.5 [ mu ] m or less, and the prepreg is obtained by impregnating reinforcing fibers with the following resin composition as a matrix resinWherein the reinforcing fiber is carbon fiber fabric, the ratio W/t of the mass W per unit area to the thickness t of the carbon fiber fabric is in the range of 700-1700, wherein the unit of W is g/m²The unit of t is mm, and the coverage factor of the carbon fiber fabric is within the range of 90-100%; wherein the resin composition is:

an epoxy resin composition comprising the following components A, B, C and D, wherein the contents of the sulfur atom and the C in the epoxy resin composition are 0.2 to 7% by mass and 1 to 15% by mass, respectively,

component A: an epoxy resin, and a curing agent,

and B component: a component B-1 which is an amine compound having at least one sulfur atom in the molecule and/or a component B-2 which is a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in the molecule,

and C, component C: a urea compound which is a compound of urea,

and (D) component: dicyandiamide;

or,

an epoxy resin composition comprising a component B-2, a component C and a component D, wherein the content of the sulfur atom and the content of the component C in the epoxy resin composition are 0.2 to 7% by mass and 1 to 15% by mass, respectively,

b-2 component: a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in the molecule,

and C, component C: a urea compound which is a compound of urea,

and (D) component: dicyandiamide.

5. The fiber-reinforced composite plate according to claim 4, wherein the forming temperature is 120 ℃ or higher.

6. The fiber-reinforced composite plate according to claim 4 or 5, wherein the resin content is 33% or less.

7. The fiber-reinforced composite panel according to any one of claims 4 to 6, wherein the fiber-reinforced composite panel is an outer panel for a transportation vehicle.

8. The fiber-reinforced composite panel of claim 4, wherein the carbon fiber fabric is on the outermost layer of the panel.

9. The fiber-reinforced composite plate material according to any one of claims 4 to 8, wherein a coating having a thickness of 20 to 200 μm is applied.

10. The fiber reinforced composite panel of claim 9, wherein the finish is a clear finish.

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