CN1944026B - Epoxy resin for prepreg, prepreg, fiber-reinforced composite material, and processes for producing these - Google Patents

Abstract

The present invention provides an excellent method for producing a fiber-reinforced composite material molded article having high strength and excellent appearance in a short period of time using a compression molding method. The manufacturing method of the fiber-reinforced composite molded article includes the steps of: pre-adjusting the temperature of the forming mold to the curing temperature of the thermosetting resin or _higher ; A step of forming a molding material (one-side surface area S ₁ ) formed by impregnating substantially continuous reinforcing fibers with a thermosetting resin; followed by closing the molding die to fill the entire inside of the molding die with the molding material; compression molding so that S ₁ /S ₂ It is a step of 0.8 to 1.

Description

Epoxy resin for prepreg, prepreg, fiber reinforced composite material and manufacturing method thereof

This application is a Chinese patent application with the filing date of the original application being November 28, 2003, the application number being 200380104284.9, and the title of the invention being "Epoxy resin for prepreg, prepreg, fiber-reinforced composite material and its manufacturing method" divisional application. the

technical field

The invention relates to an epoxy resin composition, a thermosetting resin composition, a prepreg, a fiber-reinforced composite material and a manufacturing method thereof. The epoxy resin of the present application is an epoxy resin composition especially suitable for prepregs, which can be cured in a short time at a relatively low temperature. Therefore, it is possible to obtain an excellent prepreg which has excellent mechanical properties and can be stored for a long time at room temperature. Furthermore, the thermosetting resin composition of the present invention is suitable for high-speed molding, and can exhibit high mechanical properties for a fiber-reinforced composite material (hereinafter sometimes referred to as FRP in the present invention) after molding. Therefore, excellent prepregs and fiber-reinforced composite molded articles can be obtained by using this composition. The superior prepregs provided by the present invention can be suitably used to obtain panels of fiber-reinforced composite materials that can be used as outer panels of transportation vehicles or industrial machinery. Furthermore, the present invention provides a method for easily producing FRP having high strength and excellent appearance, particularly a method for producing in a short time using a compression molding method. the

In addition, this application is based on Japanese Patent Application No. 2014 346198, Japanese Patent Application 2014 No. 347650, Japanese Patent Application 2014 No. 353760, and Japanese Patent Application 2014 No. 362519 , and incorporate its contents into this application. the

Background technique

FRP has the characteristics of light weight, high strength, and high rigidity, and is widely used in sports and leisure applications such as fishing rods and golf clubs, as well as industrial applications such as automobiles and airplanes. the

The method of using a prepreg, which is an intermediate material that impregnates a reinforcing material composed of long fibers such as reinforcing fibers with a resin, is suitable as a Manufacturing method of FRP. the

As specific methods for obtaining FRP from prepregs, there are the method using an autoclave disclosed in JP-A-10-128778, the method using a vacuum bag disclosed in JP-A-2002-159613, and JP-A-10-95048. The compression molding method disclosed in the Publication No. the

However, in any of these methods, when prepregs are laminated and shaped into a desired shape and then heated and cured, it takes about 2 to 6 hours to cure at about 160° C. or higher. That is, treatment at high temperature and for a long time is required. the

However, in order to enable mass production of products, it is required to be formed at a relatively low temperature of about 100 to 130° C. and within a short period of several minutes to tens of minutes. One of methods for achieving this problem is to shorten the time until the curing of the epoxy resin composition is completed by using an epoxy resin composition that starts a curing reaction with a small amount of heat. However, if the reactivity is too high, the curing reaction will easily run out of control, which is dangerous. However, when using a conventionally used curing agent, if the amount of the curing agent is increased, the mechanical properties may decrease. In addition, such an epoxy resin composition has a short usable period and may be cured after being stored at room temperature for only a few days. Thus, the development of epoxy resin compositions having desirable reactivity is currently expected. the

Next, the following conditions can be mentioned from the consideration of the appropriate conditions required for the prepreg. Excellent operability such as good viscosity (sticky state) and moderate drapability (softness) around room temperature;

·The workability can be maintained for a long time, that is, it has a long life near room temperature, and the formed FRP has excellent mechanical and thermal properties. the

Prepregs, which are formed by impregnating reinforcing fibers with a matrix resin such as an epoxy resin composition, are widely used as intermediate materials for fiber-reinforced composite materials. They can be used in various fields, but for the above-mentioned industrial applications, molding sexual superiority. the

At present, it takes about 1 hour for heating and curing for ordinary prepregs. As mentioned above, if including the time for temperature rise and fall, it takes about 2 or 3 hours to 6 hours for one molding depending on the conditions. This time is very long and becomes the molding cost. one of the reasons for the increase. the

However, if the heating time required for forming is shortened, the life at around room temperature will be shortened, and there is often a disadvantage that the forming temperature must be extremely high. The development of thermosetting resin compositions that impart superior properties to prepregs is ongoing. the

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

For materials used for FRP other than prepregs, molding materials such as sheet molding materials (hereinafter referred to as SMC) are often used for molding. However, the use of prepregs formed by aligning substantially continuous reinforcing fibers in one direction (hereinafter referred to as UD prepregs) and woven prepregs in the manufacture of FRP has several disadvantages as described later. Improved local SMC is advantageous especially in terms of strength of FRP. the

However, in order to efficiently obtain superior FRP, new improvements and the like are required for the currently used prepregs. the

Due to its excellent corrosion resistance, FRP sheets are being used as outer panels of transportation vehicles represented by automobiles and various industrial machinery. For example, FRP sheets called SMC are widely used in exterior panels such as hoods and fenders of automobiles. the

SMC (for example, refer to JP-A-6-286008) is a paste-like intermediate base material obtained by mixing reinforcing fibers of short fibers such as carbon fibers or glass fibers with polyester resin or the like. Heating it and applying high pressure (usually greater than or equal to 50kg/cm ² ) in the mold to shape it to make the bottom plate of the outer plate. Next, the surface of the base plate is ground with sandpaper or a file to make it flat and smooth, and then painted to form, for example, an FRP outer panel for automobiles.

The outer panel made of SMC has lower rigidity than the case where the reinforcing fibers are continuous fibers because the reinforcing fibers are short fibers (discontinuous fibers) (not only that the short fibers are reinforcing fibers, but the modulus of elasticity of glass is 70GPa, which is low to 1/3 of the elastic modulus of steel 210GPa). Therefore, the thickness of the outer plate is greater than that of the metal outer plate, and the weight may not necessarily be lighter than that of the metal outer plate, and even if it can be reduced, the weight is often reduced by a little. Furthermore, since the fibers of the SMC outer plate are discontinuous, the strength, which is an important characteristic of the outer plate other than rigidity, is low, and in particular, it is easily penetrated by a local impact such as a flying object hitting the outer plate. Therefore, it is necessary to further increase the thickness of the outer panels used outdoors such as vehicles, or to take impact-resistant protection measures such as sticking rubber. In this way, a lightweight outer panel that can replace a metal outer panel in terms of weight, that is, an environmentally friendly outer panel for transportation means cannot be obtained. the

However, the main reason why many outer plates made of SMC are put into practical use is that the random (approximately uniform) dispersion of short fibers makes it easy to obtain approximately uniform surface quality in the above-mentioned base plate before grinding. When continuous fibers are used, due to uneven distribution of fibers and irregularities in unevenness and thickness caused by twists and turns of fibers, interlacing of fibers, etc., the surface of the bottom plate has larger fluctuations than that of short fibers. Thus, for this case, the following questions arise:

1) The above-mentioned grinding operations are labor intensive;

2) During grinding, the continuous reinforcing fibers are also worn away, thereby further reducing the mechanical and functional physical properties of the above-mentioned outer panel. the

However, the case of continuous fibers is ideal because it has higher physical properties in terms of rigidity and strength, and can produce a lightweight FRP sheet. However, the forms of continuous fibers are complex and diverse, such as unidirectional prepregs, woven fabrics, and three-dimensional fabrics, but none of them have been put into practical use. the

On the other hand, research on components using continuous fibers as reinforcing fibers is also ongoing. The part is manufactured by resin transfer molding (RTM) etc., which is to laminate a prepreg formed of continuous fibers and resin aligned in one direction on a mold, and then cure with an autoclave, etc., or fabric Etc. preforms are placed in the mold and then injected with resin. However, the surface quality is low due to irregularities in the unevenness and thickness due to the twists, waves, interlacing of fibers, etc. inherent in the above-mentioned continuous fibers, and the actual situation is that they have not been practically used as outer panels of vehicles such as automobiles. . the

To improve the surface quality, a coating method called gel coat is used. The so-called gel coat method (referring to Japanese Unexamined Publication No. 11-171942) is to preliminarily form a coating of a resin material such as polyester that can become the surface of the outer plate on the inner surface of the mold, and then arrange a reinforcing fiber substrate on the coating, and Close the mold; then, inject the resin to cure it, release the mold, and transfer the coating on the surface of the FRP outer panel. The method is beneficial to industrialization because the grinding and finishing of the surface can be omitted. However, when heat curing is performed, deformation such as warping of the entire molded body occurs due to the difference in the linear expansion coefficients of FRP and gel coat. Thus, it is not suitable for an outer panel requiring precision, and is not suitable for an outer panel because the gel coat is cracked or wrinkled. the

Furthermore, since the surface of FRP using continuous fibers as reinforcing fibers has irregularities as described above, the thickness of the gel coat is 200 μm or more, which is thicker than that of the painted film in the case of painting. Therefore, there is a disadvantage that not only the weight increases, but also when the outer panel is deformed by external force, the gel coat is cracked or peeled off, so that it is not suitable for the outer panel. the

Due to the cracking or peeling of the gel coat, in the case of the gel coat of the outer panel used outdoors, moisture such as rainwater will intrude into the inside of FRP, which may impair the lightness and durability that are the characteristics of FRP. Also, in the case of gel coat, there are very few color options compared to painting, and it does not produce a metallic and stylish appearance. Therefore, there is a problem that it cannot be applied to an exterior panel such as an automobile exterior panel that needs to be colored with other parts because the value of the entire product will be lowered. It has also been considered to implement finishing on the gel coat, but in this case, problems such as further weight increase and cost increase will be produced. the

In order to improve the surface quality, other attempts have been made by adjusting the cover factor of a carbon fiber fabric used as a reinforcing fiber (see JP-A-2001-322179). the

However, it is difficult to maintain the coverage factor in an appropriate range because the carbon fiber fabric is processed into an intermediate material after being woven, cut, laminated, preformed, and formed into FRP. . If the movement of carbon fibers is constrained by caulking, the coverage factor can be kept in an appropriate range, but because the carbon fibers are constrained, the disadvantage is that it is very difficult to obtain FRP with a curved surface shape. the

As mentioned above, the actual situation is that FRP panels using prepregs, that is, prepregs in which the reinforcing fibers are continuous fibers, are not particularly practically used for outer panels, and the quantitative indicators of the structure and surface quality of FRP panels that are practical Not established. the

The coefficient of linear expansion in the thickness direction of FRP is larger than that of metal. Therefore, if the smoothness of the surface is poor, due to deformation due to temperature changes, rainwater, etc. will stay, and due to the lens effect caused by ultraviolet rays and other rays, the coating will deteriorate and spots will occur, and the outer panel will become a spotty appearance. the

The surface quality of the outer panel is known to have an important influence on the fluid resistance to air and water, in addition to the aforementioned commercial properties and long-term durability. Therefore, it is necessary to improve the surface quality in order to save energy, not only for automobiles, but also for all moving means of transportation such as trains, small aircraft, boats, and ships. Generally, if the outer panel is made of FRP for weight reduction, since the modulus of elasticity is lower than that of metal, large deformation will occur in response to the air resistance encountered during the high-speed movement of the vehicle, and the flow resistance will undergo a greater change. Therefore, the surface of the FRP sheet should be independently set different standards from the metal material. the

To repeat, in order to put FRP sheets using continuous fibers into practical use, there is an urgent need to establish comprehensive technologies such as establishing quantitative indicators suitable for the structure, material, and surface quality of FRP sheets. the

Next, the manufacturing method will be described. the

As a method of obtaining FRP from a molding material, the method using an autoclave, the method using a vacuum bag, the compression molding method, etc. are known as mentioned above. In particular, the compression molding method can be completed in a shorter molding time than the molding method using an autoclave or a vacuum bag, so it is suitable for mass production of FRP with good appearance and high strength. In addition, this method also has the advantage of being easy to manufacture FRP with complex shapes because it is easy to process a mold. the

However, when FRP is produced by compression molding using a molding material using continuous reinforcing fibers as a reinforcing material, resin with reduced viscosity flows rapidly inside or on the surface of FRP due to pressurization. And due to this flow, the arrangement of the reinforcing fibers is disturbed, so-called coil bending occurs. Then, not only the appearance is deteriorated due to the bending of the coils on the surface portion, but also the mechanical properties of FRP are degraded because the internal coils are bent due to the random arrangement of the reinforcement fibers in this portion. Therefore, the production of FRP by compression molding is limited to the case of using SMC or the like disclosed in JP-A-10-95048. the

Contents of the invention

As a result of painstaking research by the inventors of the present invention, four methods for achieving the problems described below have been provided. the

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

That is, the first aspect of the present invention is an epoxy resin composition, which is an epoxy resin composition formed by the following A component, B component, C component and D component, the sulfur atom and the The contents of component C are 0.2 to 7% by mass and 1 to 15% by mass, respectively. the

A component: epoxy resin

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

C component: urea compound

D component: dicyandiamide

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

In addition, the present inventors provide an epoxy resin composition related to the first aspect, which is composed of B-2 component, C component and In the epoxy resin composition composed of component D, the contents of sulfur atoms and component C in the epoxy resin composition are 0.2 to 7% by mass and 1 to 15% by mass, respectively. the

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

C component: urea compound

D component: dicyandiamide

Furthermore, the inventors of the present invention provide a method for producing an epoxy resin composition related to the first aspect, wherein after mixing 100 parts by mass of component A and 0.2 to 7 parts by mass of component B-1 to obtain a resin composition, further mixing When C component and D component obtain an epoxy resin composition, content of C component in an epoxy resin composition shall be 1-15 mass %. the

A component: epoxy resin

Component B: an amine compound with at least one sulfur atom in the molecule (component B-1)

C component: urea compound

D component: dicyandiamide

Another object of the present invention is to provide a thermosetting resin composition suitable for a prepreg having excellent handleability at room temperature and long life at room temperature, which are characteristic of conventional prepregs, In addition to maintaining good physical properties after molding, it also has the characteristics of high-speed molding required for industrial applications. In addition, a prepreg impregnated with the thermosetting resin composition is provided, and a method for manufacturing FRP having excellent mechanical strength and thermophysical properties at high speed using the prepreg is provided. the

This subject is achieved by the following second aspect. the

That is, the second aspect of the present application is a thermosetting resin composition having a viscosity of 5×10 ¹ to 1×10 ⁴ Pa·sec at 50°C and melting within 1000 seconds or less in an atmosphere of 120°C. A thermosetting resin composition reaching 1×10 ⁶ Pa·sec whose viscosity at 50° C. increases by 2 times or less after standing at 30° C. for 3 weeks.

Still another subject of the present application is to solve the comprehensive problem of the structure, material, and surface of an FRP board using continuous fibers, especially as an outer board. That is, to provide FRP panels that not only have light weight, high rigidity, and high strength suitable for vehicles, etc., but also have surface quality that can withstand long-term use, and have an FRP outer panel structure and materials that are environmentally friendly , Surface. This subject is achieved by the following third aspect. the

That is, the third aspect of the present application, (1) The center average roughness (Ra) of the surface of the FRP sheet obtained by heating and curing at a molding pressure of 10 kg/cm ^{2 or} more and a molding time of 15 minutes or less is less than or equal to 0.5μm prepreg; (2) FRP sheet obtained by heating and curing with a forming pressure greater than or equal to 10kg/cm ² and a forming time of 15 minutes or less, which is the center average roughness (Ra) of the surface of the FRP sheet It is an FRP sheet less than or equal to 0.5 μm.

Still another object of the present invention is to manufacture FRP having substantially continuous reinforcing fibers as a reinforcing material with high strength and excellent appearance in a short period of time by compression molding. This subject is achieved by the following means. the

That is, the fourth mode of the present application, a method of manufacturing a fiber-reinforced composite material molded article, which includes:

A step of preparing a forming mold having a common edge structure or a rubber seal structure for maintaining airtightness, and consisting of a combination of an upper mold and a lower mold, and having substantially equal thickness intervals inside the mold when the mold is closed, and a prepreg The single-sided surface area of one of the two faces is S ₂ ,

The prepreg is a prepreg in which substantially continuous reinforcing fibers are impregnated with an epoxy resin composition. The epoxy resin composition is composed of the following components A, B, C and D. The epoxy resin The contents of the sulfur atom and the C component in the composition are respectively 0.2 to 7% by mass and 1 to 15% by mass,

A component: epoxy resin

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

C component: urea compound

D component: dicyandiamide

The surface area of one of the two substantially equal surfaces of the prepreg having a thickness interval is S ₁ , and the single surface satisfies S ₁ /S ₂ =0.8~1;

The step of pre-adjusting the temperature of the forming mold to the curing temperature of the epoxy resin or above;

the step of placing said prepreg into the tempered forming mold; and

The step of closing the forming mold, performing compression molding, and filling the entire interior of the forming mold with prepreg. the

Description of drawings

1A is a cross-sectional view showing a state in which a molding material is placed inside a mold before the mold is closed;

Fig. 1B is a sectional view showing the state of the closed mold;

Fig. 2 is a cross-sectional view showing the common edge structure of the part where the upper mold and the lower mold (male and female mold) contact when the mold is preferably used in the mold used in the fourth mode of the present invention;

Fig. 3 is a cross-sectional view showing an openable and closable hole provided inside the mold preferably used in the mold used in the fourth aspect of the present invention. Blowing air from this hole can also be used for mold release of FRP. the

Detailed ways

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

first way

The first aspect of the present invention will be described below, and each component, additive, production method, and further, a prepreg obtained from an epoxy resin will be described in detail. the

This method provides an epoxy resin composition that can be cured in a short time even at a low temperature and can secure a sufficient usable time even when stored at room temperature, compared with conventional epoxy resin compositions. According to the prepreg obtained using this resin, a fiber-reinforced composite material exhibiting excellent mechanical properties can be obtained. the

(A component)

Component A in the first aspect is an epoxy resin. Examples of the difunctional epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, or modified epoxy resins such as Epoxy after substance etc. Examples of trifunctional or more polyfunctional epoxy resins include novolac epoxy resins, cresol epoxy resins, tetraglycidyl diaminodiphenylmethane, triglycidylaminophenol, tetraglycidylaminophenol, Glycidylamine-type epoxy resins such as glycidylamine, glycidyl ether-type epoxy resins such as tetrakis(glycidyloxyphenyl)ethane and tris(glycidyloxymethane), and those modified Epoxy resins, brominated epoxy resins after bromination treatment of these epoxy resins, but not limited thereto. Moreover, you may use these epoxy resins combining 1 or more types as A component. the

In particular, bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, novolak epoxy resins, and cresol novolac epoxy resins can be used particularly preferably. These epoxy resins have the effect of further improving the mechanical strength of molded products compared to the case of using a highly rigid epoxy resin such as an epoxy resin having a naphthalene skeleton in the molecule, for example. This is because, if a highly rigid epoxy resin is cured in a short time, strain is likely to occur due to an increase in crosslinking density, whereas if the above-mentioned epoxy resin is used, such a problem is less likely to occur. the

On the other hand, as epoxy resins having a sulfur atom in the molecule, there are bisphenol S-type epoxy resins and epoxy resins having a sulfur skeleton, and these can also 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 of previously quantifying the content of sulfur atoms in the epoxy resin composition, atomic absorption spectrometry or the like can be used. the

(B component)

Component B of the first embodiment is an amine compound having at least one sulfur atom in its molecule (component B-1) and/or a reaction product of an epoxy resin and an amine compound having at least one sulfur atom in its 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 its molecule. For example, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4' -Diaminodiphenyl sulfide, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, 4,4'-diaminodiphenyl Base sulfide, o-toluidine sulfone, and derivatives of these substances, etc. the

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

Moreover, in the process of manufacturing the epoxy resin composition of this form, some or all of the substances added as A component and B-1 component may be changed into B-2 component. the

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

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

(C component)

The C component in this form 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 has high reactivity and low toxicity, and thus can be used particularly suitably as the C component. the

The urea compound mentioned in the present invention may also contain ammoniated compounds of carbonic acid and ammoniated compounds of carbamic acid. Generally, it can be obtained by reacting phosgene, chloroformate, carbamoyl chloride, carbonate, isocyanate, cyanic acid, etc. with ammonia and other amines. the

Compounds generally called ureas, such as ureides (acylureas) obtained by reacting urea with acid chlorides and alkylureas (alkylureas) obtained by substituting hydrogen of urea with a hydrocarbon group, are also included in the urea compound in this embodiment. the

In addition, the urea compound referred to in this embodiment also includes urea adducts. the

The urea adduct, as an example, refers to a substance in which hydrocarbons have been introduced into the crystal structure of urea obtained by mixing a saturated aqueous solution of hydrocarbons and urea or a saturated solution of a lower alcohol such as methanol. the

The content of component C in the epoxy resin composition needs to be 1 to 15% by mass. It is preferably equal to or greater than 3% by mass, and preferably equal to or less than 12% by mass. If it is less than 1% by mass, the curing reaction may not be fully completed; if it exceeds 15% by mass, the usable period will be short, and it may not be possible to store it for a long time around room temperature. the

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

(Component D)

Component D in the first aspect is dicyandiamide. This dicyandiamide functions as a curing agent for epoxy resin, and can be cured at a relatively low temperature by using it in combination with other components in this embodiment. the

In this form, it is preferable that content of D component in an epoxy resin composition is 0.1-10 mass %. Moreover, when the average particle diameter of component D is 150 micrometers or less, especially 50 micrometers or less, since dispersibility becomes favorable and a reaction rate becomes fast, it is preferable. the

(other additives) 

In the epoxy resin composition of the first aspect, it is also possible to add an appropriate amount of inorganic particles such as fine powdered silica, pigments, elastomers, aluminum hydroxide and bromide or phosphorus compounds as flame retardants, defoaming agents, Thermoplastic resins dissolved in epoxy resins such as polyvinyl acetal resins and phenoxy resins for the purpose of improving workability and flexibility, imidazole derivatives, metal complex salts, or tertiary amine compounds as catalysts for curing reactions wait. the

(content of sulfur atom in epoxy resin composition)

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

(gel time)

The epoxy resin composition of the first aspect preferably has a gel time at 130° C. of 200 seconds or less. In this embodiment, the gel time refers to the time until gelation is completed when the uncured epoxy resin composition is raised to a specific temperature. Here, gelling refers to a state in which the epoxy resin composition forms a three-dimensional network structure between molecules and loses fluidity. the

The epoxy resin composition whose gel time at 130° C. is 200 seconds or less can be cured in a short time. the

(Manufacturing method of epoxy resin composition) 

The manufacturing method of the epoxy resin composition of this form can add and mix the above-mentioned A component, B-1 component, C component, D component, and other additives in appropriate amounts, for example. At this time, as described above, a part or all of the added A component and B-1 component may react and be changed into B-2 component. the

Moreover, you may mix A component and B-1 component previously, after preparing the resin composition containing B-2, you may mix C component and D component again. the

In addition, the temperature at the time of mixing is preferably 50 to 180°C, more preferably 60 to 160°C. the

(Prepreg)

By impregnating reinforcing fibers with the above-mentioned epoxy resin composition as a matrix resin, a prepreg that can be molded at a relatively low temperature in a short time is obtained. Manufacture of the prepreg can be performed by known equipment and production methods. the

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

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

In addition, 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 woven form, or a nonwoven fabric using chopped reinforcing fibers, or the like. In particular, in the case of a form aligned in one direction and a woven form, the conventional compression molding method took time until curing, and the resin would flow in the mold, so a fiber-reinforced composite material with a good appearance could not be obtained. . However, if the epoxy resin composition of this embodiment is used, since the epoxy resin composition cures in a short time, a fiber-reinforced composite material with a good appearance can be obtained. the

second way

The second aspect of the present invention will be described below, and specific descriptions of each sentence, preferred examples of this aspect, and the like will be described in detail. the

According to the second method, an excellent thermosetting resin composition suitable for prepregs is provided, which is excellent in workability at room temperature and long life at room temperature, and can maintain good physical properties after molding, and can Performs high-speed forming required for industrial applications. the

[Determination of viscosity]

As a result of earnest studies by the present inventors to solve the above-mentioned problems, it was confirmed that the viscosity of the thermosetting resin composition, the time to reach the target viscosity in a heated state (specifically, 120° C.), and the viscosity after standing are important. In the second embodiment, the viscosity is measured using RDS-200 manufactured by Rheometrics (a dynamic viscosity measuring device having equivalent performance is also possible), and the obtained value is a value measured at a frequency of 1 Hz using a 25 mmφ parallel plate. The conditions for raising the temperature to the heated state (specifically, 120° C.) will be described in detail in that section. the

[Viscosity at 50°C is 5×101～1×10 ⁴ Pa·sec]

The thermosetting resin composition of the second aspect needs to have a viscosity at 50°C of 5×10 ¹ to 1×10 ⁴ Pa·sec.

When the viscosity is less than 5×10 ¹ Pa·sec, the viscosity becomes too strong at around room temperature when it is made into a prepreg, and handling becomes very difficult. On the contrary, when the viscosity exceeds 1×10 ⁴ Pa·sec, the drape property of the prepreg is lost and becomes hard, and it becomes difficult to handle.

[1×10 ⁶ Pa·sec in 1000 seconds or less in an atmosphere of 120°C]

Next, in the second mode, the thermosetting resin composition must reach 1×10 ⁶ Pa·sec at 120° C. within 1000 seconds or less.

When the time until the viscosity reaches 1×10 ⁶ Pa·sec exceeds 1000 seconds, the molding time at high temperature is long. 800 seconds or less is preferable because the molding time at high temperature is short, and 600 seconds or less is more preferable.

The measurement method used the method described in [Measurement of Viscosity], and the conditions for raising the temperature to the temperature of the heated state (specifically, 120° C.) were implemented as follows. That is, after the thermosetting resin composition sample was fixed at 50°C, the temperature was raised to 120°C at a heating rate of 10°C/min, and the isothermal viscosity was measured at 120°C. Time was counted from the time when the temperature reached 120° C., and the time until the viscosity reached 1×10 ⁶ Pa·sec was counted. When it is difficult to measure the viscosity up to 1×10 ⁶ Pa·sec, the lowest viscosity can be measured up to about 1×10 ² Pa·sec, and the time to reach 1×10 ⁶ Pa·sec can be calculated by extrapolating the last two points. However, it is necessary to carry out the viscosity measurement of 1 digit or more even at the minimum. That is, when the viscosity of 1×10 ⁶ Pa·sec is obtained by extrapolating the data at 1×10 ² Pa·sec, the viscosity at 120°C must be equal to or less than 1×10 ¹ Pa·sec.

[Viscosity at 50°C increased by 2 times or less after standing at 30°C for 3 weeks]

In addition, the thermosetting resin composition of the second embodiment must have a viscosity increase of 2 times or less at 50°C after being left at 30°C for 3 weeks. the

The measurement method of viscosity is the same as [measurement of viscosity]. When the viscosity is increased by more than 2 times, the stability of the prepreg around room temperature deteriorates. the

[Resin Composition]

The raw material of the thermosetting resin composition of the second aspect is not particularly limited, and examples thereof include epoxy resins, phenolic resins, vinyl ester resins, unsaturated polyester resins, bismaleimide resins, bismaleimide three Oxazine resins, cyanate resins, benzoxazine resins, acrylic resins, etc., but epoxy resins, bismaleimide resins, and bismaleimide resins are preferably used in view of workability and cured product properties. Triazine resins, cyanate resins, and especially epoxy resins are excellent in adhesion to reinforcing materials, and thus are particularly preferably used. the

A thermoplastic resin and other additives may be added to the thermosetting resin composition of this embodiment in order to improve the handleability of the prepreg, improve the appearance of the molded FRP, and improve physical properties such as impact resistance. the

Examples of thermoplastic resins that can be suitably added to the second embodiment include aramid, polyester, polyacetal, polycarbonate, polyphenylene ether, polyphenylene sulfide, polyarylate, and polyimide. , polyetherimide, polysulfone, polyamide, polyamideimide, polyetheretherketone, etc. the

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

[addition of filler]

In order to improve the surface smoothness of the obtained FRP, it is preferable to add a filler such as a filler to the thermosetting resin composition of the second aspect. Calcium carbonate is preferred as the filler, and the particle size of calcium carbonate is preferably 3-10 μm. the

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

In addition, needless to say, when the above-mentioned additives are added to the thermosetting resin composition of the present embodiment, the thermosetting resin composition finally impregnated into the prepreg must also satisfy the above-mentioned viscosity condition. the

[Prepreg]

The prepreg of the second aspect is a prepreg formed by impregnating a reinforcing material with the thermosetting resin composition of the present invention. The material of the reinforcing material used in the prepreg of this form is not particularly limited, and examples thereof include carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber, boron fiber, steel fiber, etc., but preferably Carbon fibers and glass fibers are used to obtain excellent FRP performance, especially light weight, high strength, and high rigid mechanical properties. the

The form of the reinforcing material used in the prepreg of the second aspect is not particularly limited, and examples include those in which plain weave, twill weave, satin weave, or fiber bundles are laminated in one direction or at different angles. Seamed pieces such as non-crimpfabric, non-woven fabrics, spacer-like objects that are stitched so that they do not unravel, and unidirectional materials formed by aligning reinforcing fibers in one direction etc., but it is preferable to use a fabric or a seamed sheet that is superior in workability. the

The resin content of the prepreg of this embodiment is not particularly limited, but the smaller the resin content, the better the appearance of the obtained FRP and the greater the reinforcing effect of the reinforcing material, so it is preferable. Specifically, the volume content of the thermosetting resin composition in the prepreg is preferably equal to or less than 45% by volume, more preferably equal to or less than 40% by volume, particularly preferably equal to or less than 35% by volume. the

Regarding the lower limit of the volume content of the thermosetting resin composition in the prepreg, if the content of the thermosetting resin composition is too small, the thermosetting resin composition may not fill every corner of the FRP, which is not preferable. Specifically, the content of the thermosetting resin composition is preferably equal to or greater than 20% by volume, more preferably equal to or greater than 25% by volume. the

[Manufacturing method of FRP]

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

The heating temperature is also not particularly limited, but the higher the temperature, the shorter the molding time is, and it is preferable. Specifically, it is preferably equal to or higher than 120°C, more preferably equal to or higher than 140°C. However, if the temperature is too high, it will take a lot of time to lower the temperature of the molding die, or when the prepreg is placed without lowering the temperature, the resin may not reach the corners of the final molded product due to the start of curing. Therefore, heating is preferably equal to or lower than 200°C, more preferably equal to or lower than 180°C. There is also no particular limitation on the degree of pressurization, but it is preferable to perform high-pressure forming because pinholes on the surface and voids inside the FRP can be reduced. Specifically, the pressure applied to the prepreg is preferably equal to or greater than 0.5 MPa, more preferably equal to or greater than 1 MPa. An upper limit of 100 MPa is sufficient. the

There are no particular restrictions on the forming equipment and style, but the method using hydraulic heating and pressing equipment has the best efficiency and is suitable for the FRP manufacturing method of the present invention. For the forming die at this time, it is preferable to have a forming die of a closed system with a common edge structure. the

third way

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

In the third aspect, an excellent prepreg and an FRP sheet material can be provided that can solve the comprehensive problems of the structure, material, and surface of the FRP sheet material using continuous fibers, especially as an outer panel. the

<prepreg>

[Forming pressure]

For the prepreg of the third mode, in order to have a good surface quality with a centerline average roughness (Ra) of the FRP sheet less than or equal to 0.5 μm, and to have a surface quality that can withstand long-term use, it is necessary to use a weight greater than or equal to 10kg/cm ² The forming pressure forms a prepreg against substantially continuous reinforcing fibers impregnated with a matrix resin.

When the pressure during molding is less than 10 kg/cm ² , it is difficult to form a good surface quality.

[forming time]

In the third aspect, in order to obtain an FRP sheet for particularly cost-conscious transportation applications, it is necessary to perform heat curing within 15 minutes or less, more preferably within 10 minutes or less. In the present invention, the molding time refers to the time during which the prepreg is left in a state where molding temperature and pressure are applied. the

[reinforcing fiber]

The reinforcing fibers that can be used in the third aspect are not particularly limited as long as they are substantially continuous reinforcing fibers, 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 most suitably used as parts of aircraft, automobiles, and the like. the

The form of the reinforcing fiber in the molding material can be a form in which the reinforcing fiber is aligned in one direction, a form in which the reinforcing fiber is woven, etc., and is not particularly limited. For example, in order to improve the appearance of FRP, the forming material on the surface of FRP can be reinforced with a fabric of reinforcing fibers, and the reinforcing fibers can be aligned in one direction inside, and multiple reinforcement forms can be used. the

In addition, in this specification, a substantially continuous reinforcing fiber refers to a fiber that does not substantially have an end portion inside the molding material. the

In the prepreg of this embodiment, carbon fibers are preferably used as the reinforcing fibers. Carbon fiber can use either PAN (acrylonitrile) type or pitch type. PAN-based carbon fibers are more preferable for making fabrics in view of the balance of strength, elastic modulus, and elongation. For outer panel applications, higher strength and elastic modulus are more desirable, but carbon fibers with an elongation of 1.4% or more are preferable in order to impart impact resistance. The elongation of FRP is calculated according to JISK-7054, and therefore strictly refers to the tensile breaking strain. the

[Carbon Fiber Fabric]

Carbon fiber fabrics form plain weave, twill weave, satin weave and other fabric forms in the state of continuous fibers. Among them, the fabric in the present invention preferably has a ratio (W/t) of the weight per unit area (W g/m ² ) to the thickness (tmm) of the carbon fiber fabric in the range of 700-1700.

The fabric in this range is called thin fabric, which is relatively thin in terms of mass per unit area and has a structure of fiber diffusion. Since the fluctuation in the thickness direction of the fiber is small, it can exhibit high strength and rigidity, making the outer panel more lightweight. In addition, since the unevenness of the surface of the fabric is small, the surface quality of the outer panel is also improved, and the durability of the FRP sheet is also improved. In addition, the mass per unit area and thickness of the fabric are measured in accordance with JIS R7602. the

Furthermore, when the coverage factor of the carbon fiber fabric is in the range of 90 to 100%, the portion formed only by the resin is extremely small, and the out-of-plane impact characteristics become high, and the surface unevenness or uneven spots caused by the shrinkage of the resin in the thickness direction disappears, It is preferable to obtain high mapping sharpness. In penetrating impact, assuming that the flying object is a small piece, the more preferable coverage factor is within the range of 95 to 100%. the

The cover factor Cf of the carbon fiber fabric, as described and defined in JP-A-7-118988, is an element related to the size of the gap formed between the textile yarns. When setting the area of the area S on the fabric, if The area of the voids formed between the weaving yarns within the area S is defined as s, which is a value defined by the following formula. the

Coverage factor Cf(%)＝{(S-s)/S}×100

In addition, since the fabric contributes to the surface rigidity and surface quality which are particularly important among the physical properties of the outer panel, the location of the fabric is preferably near the surface layer of the panel. The presence of highly rigid carbon fiber on the surface of the outer panel further increases the surface rigidity of the outer panel and enables weight reduction. the

The most preferred location is the outermost layer. Moreover, if the multiaxial fabric such as biaxial or triaxial is on the outermost layer, it can also give the outer panel a unique fabric appearance. Furthermore, by making the fabric with the relationship between the mass per unit area and the thickness in the above-mentioned range located in the outermost layer, the surface of the outer panel becomes extremely smooth, and it is also extremely smooth when a thin coating film is provided. the

That is, the above-mentioned thin fabric in which the ratio (W/t) of the mass per unit area (W g/m ² ) to the thickness (tmm) of the carbon fiber fabric is in the range of 700 to 1700 has small unevenness and meandering along the thickness direction of the fiber. , so the thickness of the resin layer on the surface changes little when it is made into an outer plate, and a smoother surface can be obtained before and after painting.

In addition, if the coverage factor is in the range of 90 to 100%, there will be no part made of only resin in the thickness direction of the outer plate, so that the sharpness of the image, which is an extremely important characteristic in terms of durability, will be improved, and the practicality will be increased. , so it is preferred. the

[Reinforcing fiber other than carbon fiber]

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 regularly or irregularly arranging long fibers, short fibers, fabric-like, spacer-like objects, or a mixture of these forms in carbon fibers or resins, impact resistance, shock-absorbing properties, etc. can be improved. the

In particular, glass fibers are inexpensive and have a good compression/tensile strength balance. The glass fiber refers to fibrous glass such as so-called E glass, C glass, and S glass mainly composed of silica (SiO ₂ ), and preferably has a fiber diameter of about 5 to 20 μm. Glass cloth can hold resin while improving rigidity, so formability is good. Suitable glass cloths have a mass per unit area of 20 to 400 g/m ² . When used for the surface layer, if it is 20 to 50 g/m ² , the appearance of the fabric will not be impaired, and transparency can be maintained, so it is preferable.

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

In addition, organic fibers are not brittle like carbon fibers and glass fibers, but tough, which is flexible, and has the characteristic that it is not easy to break even when bent. In addition, synthetic fibers have the advantage of not requiring electrical corrosion countermeasures compared with carbon fibers because they do not cause electrical corrosion. the

In addition, compared with glass fibers, organic fibers have the advantage of being easy to discard because they are combustible, and also have the advantage of making parts extremely lightweight because their specific gravity is about half that of glass fibers. the

[Matrix resin]

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

Among them, epoxy resins, polyester resins, vinyl ester resins, and modified resins of these resins are preferable, which are superior in chemical resistance, weather resistance, and the like. In addition, phenolic resins and benzoxazine resins are excellent in flame retardancy, and are preferable for outer panels requiring heat resistance. the

Furthermore, transparent resins such as acrylic resins are preferable in terms of appearance. Among them, acrylic resins are preferable because of their excellent weather resistance. Furthermore, weather resistance can be further improved by adding 3 to 20% of ultraviolet absorbers, solar absorbers, and antioxidants to these transparent resins. the

[Resin composition (1)]

Furthermore, the epoxy resin composition which is the 1st aspect of this invention is mentioned as a preferable matrix resin used by a 3rd aspect (refer to description of 1st aspect, it may describe as resin composition (1) below). In addition, the materials, conditions, preferred examples, and the like described in the resin composition of the first aspect are also preferable in the third aspect unless there is a particular problem. the

When the resin composition (1) is used, it can be cured in a short time at a relatively low temperature, so the prepreg obtained by using the epoxy resin composition has a sufficient usable period even if it is stored at room temperature, and The FRP sheet obtained from this prepreg exhibits excellent mechanical properties. Furthermore, by using this prepreg, the processing time can be shortened in the molding of the fiber-reinforced composite material, so that it can be produced at low cost. the

(other additives) 

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

(Content of sulfur atoms in the resin composition (1))

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

(gel time)

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

(Manufacturing method of resin composition (1))

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

(Prepreg)

In the third aspect, similarly to the first aspect, it can be obtained by impregnating the above-mentioned resin composition (1) as a matrix resin into reinforcing fibers. The same types and forms of reinforcing fibers as those in the first embodiment can be used, and preferred examples are also preferred. the

The form of the reinforcing fiber in the prepreg is not particularly limited, and may be a form in which the reinforcing fiber is aligned in one direction, a form in which the reinforcing fiber is woven, or a nonwoven fabric using chopped reinforcing fiber, or the like. In particular, in the case of a form aligned in one direction and a woven form, conventional molding by compression molding takes time until curing, and the resin flows in the mold, so a fiber-reinforced composite with a good appearance cannot be obtained. However, if the epoxy resin composition of this embodiment is used, since the epoxy resin composition cures in a short time, a fiber-reinforced composite material with a good appearance can be obtained. the

As described in detail above, the resin composition (1) can be cured in a short time at a relatively low temperature. Therefore, the prepreg obtained by using the epoxy resin composition has a sufficient usable period even if it is stored at room temperature, and the composite material obtained from the prepreg exhibits excellent mechanical properties, such effects can be obtained . Furthermore, by using this prepreg, the processing time can be shortened in the molding of the fiber-reinforced composite material, so that it can be produced at low cost. the

[Resin composition (2)]

In addition, as the base resin preferably used in the prepreg of the third aspect, in view of its curing characteristics, the thermosetting resin composition of the second aspect of the present application is used (refer to the second aspect, and may be described as a resin combination hereinafter). Substance (2)) is also preferred. In addition, the materials, conditions, preferred examples, and the like described in the resin composition of the second aspect are also preferable in the third aspect unless there is a particular problem. the

This thermosetting resin composition is suitable as a matrix resin for a prepreg capable of high-speed molding required for industrial use while maintaining workability at room temperature, long life at room temperature, and good physical properties after molding. In addition, prepregs can perform high-speed molding required for industrial use while maintaining workability at room temperature, long life at room temperature, and good physical properties after molding. the

Next, the resin composition (2) is demonstrated in detail. the

(Determination of viscosity)

Measurement was performed in the same manner as in the second embodiment. the

(Viscosity at 50°C is 5×10 ¹ to 1×10 ⁴ Pa·sec)

The description is the same as that in the second embodiment. the

(Reach 1×10 ⁶ Pa·sec within 1000 seconds in an atmosphere of 120°C)

The description is the same as that in the second embodiment. the

(Increase in viscosity at 50°C by 2 times or less after 3 weeks at 30°C)

The description is the same as that in the second embodiment. the

(resin composition)

Similarly, the resin composition described in the second aspect can be used. the

(addition of filler)

The description in the second aspect can be used similarly. the

(Prepreg)

It can be produced in the same manner as described in the second aspect. Preferred examples such as the amount and material in the second aspect are also preferable in the third aspect. the

(Manufacturing method of FRP) 

FRP can be manufactured in the third aspect similarly to the second aspect. Examples of preferable manufacturing conditions, methods, and equipment in the second aspect are also preferable in the third aspect. the

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

Furthermore, the prepreg obtained from the resin composition (2) can perform high-speed molding required for industrial use while maintaining workability at room temperature, long life at room temperature, and good physical properties after molding. Furthermore, high-speed forming required for industrial use can be performed. The resin composition (2) is very suitable for high-speed molding, and contributes greatly to reducing molding processing costs, which is the biggest drawback of FRP. the

[Proportion of matrix resin in prepreg] 

The ratio of the matrix resin in the prepreg is preferably within a range of 20 to 45% by mass. This is because, if it exceeds 45%, weight reduction may have to be sacrificed in order to make the rigidity and impact resistance of the FRP flat panel similar to that of the metal outer panel. the

In addition, the reason why it is 20% or more is because if it is less than 20%, impregnation with the matrix resin becomes difficult, voids are generated, and physical properties may be poor. the

The ratio 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, which is preferable. the

[Surface Roughness - Center Average Roughness (Ra)]

The center average roughness (Ra) of the surface of the FRP obtained under the above-mentioned molding conditions for the prepreg of this form is 0.5 μm or less, which is considered in terms of poor appearance and low durability due to unevenness on the surface of the FRP sheet. Said it was necessary. It is more preferable that the center average roughness (Ra) is 0.5 μm or less. The unevenness cannot be eliminated by painting, and it will be more obvious. In addition, not only the appearance is damaged, but also the stress concentration at the tip of the concave part increases according to the size, and the fracture is promoted. Therefore, the durability of the outer panel can be improved when the unevenness is small. the

In this method, the center average roughness (Ra) of the FRP surface is a surface roughness measuring instrument 178-368 (analysis unit 178) manufactured by Mitutoyo Corporation, with an intercept value of 2.5mm and a measurement interval of 2.5× 5mm, range: 5μm for measurement. Of course, the surface of the FRP may have unevenness due to damage to the mold surface, and therefore such portions are excluded from the above-mentioned measurement. the

[Forming method]

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

Preliminarily adjust the temperature of a mold with a surface accuracy of #800 or higher to the curing temperature of the thermosetting resin composition or above, which has a structure that allows gas to flow out from the inside of the mold but can suppress resin outflow when the mold is closed, and put The above-mentioned prepreg laminate composed of continuous carbon fibers is introduced, and then the mold is closed to fill the entire interior of the mold with the prepreg laminate and compression molded. the

In addition, the "structure that allows gas to flow out from the inside of the mold and suppresses resin outflow" that the mold has generally includes a structure called a common edge structure and a rubber seal structure. the

In addition, the mold preferably has a structure capable of degassing the inside when the mold is closed or is being closed. the

As the degassing structure, there is an openable or closable hole inside the mold, which is open outside the mold, and the above-mentioned hole is connected to a container for degassing the inside by a pump through a valve. When the mold is closed, the valve is opened and the inside of the mold is One-gas degassing and other methods. the

Furthermore, after the forming of the FRP sheet is completed, in order to facilitate the removal of the FRP sheet, a mechanism for releasing the FRP sheet, such as an ejector pin and an air valve, may be installed on the mold. As a result, the FRP sheet can be easily taken out without waiting for the mold to cool down, making it suitable for mass production. In addition, the mechanism for demolding may be an ejector pin, an air valve, or other mechanisms, or any conventionally known mechanism. the

Put the above-mentioned laminate of prepregs made of continuous carbon fibers (with a surface area of one side as S 1 ) in the mold (with a surface area of one side as S ₂ ) in a state where S ₁ /S ₂ is 0.8 to 1, and _the matrix It is preferable that the resin does not flow extremely under pressure. The flow of the matrix will cause the reinforcing fibers to flow, thereby causing unevenness on the surface of the FRP sheet. The unevenness cannot be eliminated by painting, and it will be more obvious. In addition, not only the appearance is damaged, but also the stress concentration at the tip of the concave part increases according to the size, and the fracture is promoted. Therefore, the durability of the outer panel can be improved when the unevenness is small.

The FRP sheet can be obtained by releasing the mold after curing, and then applying uniform coating methods such as spray guns. Since the molding shrinkage and thermal shrinkage of the resin during molding will also affect the surface quality, epoxy resins with small molding shrinkage of resins, and low-shrinkage resins mixed with fillers such as talc, glass particles, and calcium carbonate are preferred. the

The forming temperature is preferably 10°C or more higher than the temperature used for the outer panel, and for automotive outer panels, it is 90°C or higher, more preferably 110°C or higher, and 130°C or higher is from the aspect of shortening the forming time Said to be preferred. the

[FRP sheet]

The thickness of the FRP sheet varies depending on the application, but it is preferably in the range of 0.5 to 8 mm in the case of an outer panel of a vehicle that runs on the ground such as an automobile. If it is below this range, there may be a problem with the penetration resistance; if it is above this range, the lightweight property will be insufficient. the

In the case of a vehicle running in the air, since the speed is faster, the range of 1 to 10 mm is preferable. the

In addition, a sandwich structure, a corrugated structure, or a structure in which a frame is provided on a part of the outer plate is also a preferable solution. the

For the FRP sheet of the third form, by using continuous carbon fiber as a reinforcing fiber, it can exhibit high elastic modulus and strength, which are one of the characteristics of carbon fiber, and can realize the resistance to dents necessary as an outer panel with a light weight, Rigidity, strength. In addition, since it is a continuous fiber, it is possible to obtain the penetration impact resistance characteristic which is extremely important as an outer panel. That is, lightweight, rigidity, and impact properties that cannot be achieved with short fibers can be obtained. Of course, deformation resistance, maximum load, displacement, and energy absorption are also large. the

Furthermore, since the continuous fibers have a fabric form, compared with the case where prepregs aligned in one direction are laminated, the penetrating impact resistance is higher despite the same amount of reinforcing fibers. The principle is that the fabric is a net-like structure with interlaced fibers, so that flying objects can be caught. the

In addition, compared with the case of laminating prepregs with equal physical properties in two directions perpendicular to one layer (single layer) and arranged in one direction, the fabric can constitute the outer panel with a smaller number of sheets, thereby Lighter. For example, in the case of an outer panel in which two prepregs are laminated perpendicularly, an out-of-plane distortion called a saddle occurs due to heat shrinkage during curing. This out-of-plane deformation does not come from external force, but also occurs due to temperature changes. In-plane stress also occurs when acting on the outer plate, which deforms the outer plate, which is not preferable in terms of appearance and aerodynamics. the

Furthermore, by using lightweight, high elastic modulus, and high-strength carbon fibers as reinforcing fibers, the outer panel can be made lightweight and have high mechanical properties, and is also excellent in environmental resistance. the

[finishing]

The FRP plate of the present invention can be coated on the surface. Finishes are thinner (typically 150 microns or less) than gel coats and are lightweight. There are many choices of not only color but also characteristics by painting. By selecting an appropriate coating, it is possible to impart characteristics or functions that cannot be provided by FRP sheets alone, such as gloss or unevenness on the surface, low-temperature and high-temperature environments, water resistance, and UV resistance. the

For example, when the resin part of the FRP sheet is a resin with weak ultraviolet resistance, by applying a coating with excellent ultraviolet resistance, it is possible to impart ultraviolet resistance characteristics as an outer panel. Of course, various appearances (makeup) are also possible, and painting is also preferable from the aspect of appearance. For the outer panel, it is necessary to match the color with other parts in consideration of safety, etc., and it is possible to carry out subtle color matching through painting. In addition, by coating, moisture and light do not directly enter the FRP, so a highly durable outer panel with excellent environmental resistance can be obtained. Furthermore, the finish is also preferable in terms of fluid resistance. the

In addition, the coating thickness is preferably 20 to 200 μm. If it exceeds 200 μm, the coating film will easily peel off, which is not preferable in terms of mechanical properties and appearance. If it is less than 20 μm, light rays such as sunlight will directly enter to cause deterioration, and coating unevenness will easily occur, which is not preferable also in terms of appearance. Within this range, it is possible to form an FRP outer panel that does not require an increase in weight and is ideal in terms of durability. More preferably, it is 40-100 micrometers. the

Paint can be selected from paints such as silicon/epoxy resin paint, acrylic resin paint, urethane resin paint, polyester resin paint, epoxy resin paint, fluororesin paint, urushiol resin paint, alkyd resin paint, Amino alkyd resin coatings, phenolic resin coatings, oil-based coatings, oil-based varnishes, synthetic resin coatings such as nitrocellulose and nitrocellulose, and water-soluble resin coatings, including primer surfacer, primer surfacer, putty, etc. coating. the

Coatings are roughly classified into one-component, two-component, and multi-component natural drying or room temperature drying coatings, baking varnishes, ultraviolet curing coatings, and electron beam curing coatings. And, according to the finishing method, it can be divided into paint for spraying, paint for roller coating, paint for flow coating, paint for brushing, and the like. the

In addition, for the selection of paint, it is preferable to select a paint composition with good resin adhesion to FRP. In addition, since FRP has inferior ultraviolet resistance compared to metal, a coating superior in weather resistance is preferable. Specifically, it is a coating called a sun-blocking paint and an ultraviolet-ray blocking paint. There are alkyd, acrylic, and urethane vehicles that use carbon black as a pigment and blend UV absorbers or reduced telomer polybasic acids, etc. The resulting paint, acrylic, urethane, epoxy, silicone paint, fluorine-based paint, etc., to which black pigments such as cobalt oxide, copper oxide, and iron oxide black are added. Especially in the case of clear finishes, the above-mentioned additives are indispensable. the

Also, a conductive paint in which conductive fillers such as carbon black, graphite, and metal powder are dispersed is preferable. The paint with the addition of tin oxide or antimony oxide-based conductors can form a transparent conductive coating film. Therefore, when using the appearance of carbon fiber fabrics, or the purpose is to provide a coating that can prevent dust and dirt caused by static electricity from adhering to It is a preferable conductive paint for the antistatic effect of the outer panels of automobiles and the like. the

In addition, it is also effective to apply a luminescent paint (luminous paint) described in JIS K5671 to the whole or part of the outer panel of the outer panel of a vehicle that requires attention at night or the like. the

In addition to spray (blowing) coating (air gun and airless method, etc.), electrostatic coating (electrostatic spraying method and spray gun method, etc.), electroplating coating (cationic and anionic, etc.), powder coating (solution spray method, flow method, etc.) In addition to impregnation method, electrostatic powder coating method, etc.), known special coating methods can also be applied. the

Among them, since the heat resistance of the FRP sheet of this embodiment is lower than that of metal, the drying temperature is 120° C. or lower, and the electrostatic coating using FRP as the anode is superior in paintability, so it is preferable. In addition, since carbon fibers are conductive, electrostatic painting is also a preferred finishing method with high paint usage efficiency. the

In addition, when coating with a certain thickness, the surface of the FRP sheet is preferably degreased or polished to remove the release agent. By using non-silicon-based materials as release agents, degreasing or grinding operations can be eliminated or reduced. The coating temperature is closely related to the heat-resistant temperature of the outer panel, and it is preferable to carry out the coating drying near the heat-resistant temperature. In the case of an automobile outer panel, the heat-resistant temperature is about 100°C, and the drying temperature of the paint is preferably in the range of 60 to 110°C. In addition, the drying time is about 3 minutes to 60 minutes. the

The color of the coating is determined by the color matching with other parts, but for the FRP outer panel of this embodiment, which uses carbon fiber fabric as a reinforcing base material, it is preferable to perform a transparent coating that allows visual observation of the deterioration state and internal damage state of the FRP part. Since it is transparent, it is possible to accurately grasp the state of FRP, and it also has the effect of giving a third party who has only experience with metal outer panels the opportunity to use the FRP outer panel. Of course, clear coating also has the effect of improving the value of goods by utilizing the appearance of the fabric structure. In addition, the clear coating may be the whole or a part of the outer panel. the

In addition, typical clear paints are silicon/epoxy paints and acrylic paints, but they may also be urethane paints, or mixtures of these paints, or alloy paints, and may be colored and transparent. the

For carbon fiber fabrics, fabrics with a large ratio of mass per unit area to thickness are suitable. Finishing uses a finishing method such as a spray gun that can form a uniform and thin coating film. If the coating film is too thin or too thick, the sharpness of the reflection tends to decrease, so it is preferable to form it to an appropriate thickness. the

[Use of FRP sheet] 

The FRP plate of this mode can be used as the inner and outer plates of transportation tools such as two-wheel vehicles, automobiles, high-speed vehicles, high-speed boats, bicycles, bicycles, and aircrafts. the

Specifically, for the following applications: two-wheeled vehicle panels such as motorcycle frames, fairings, and fenders; doors, hoods, rear doors, side fenders, side panels, fenders, rear trunk lids, roof Covers, side mirror covers, spoilers, diffusers, luggage racks and other automotive panels, engine cylinder heads, engine covers, chassis and other automotive parts, leading vehicle fronts, roofs, side panels, doors, trolley covers, side skirts Vehicle outer panels, cargo sheds, seats and other vehicle interior appliances, airfoil inner panels, outer panels, top covers, floor panels, etc. in airfoil trucks, air spoilers and side skirts installed on cars or bicycles Aircraft applications such as window frames, cargo sheds, seats, floor panels, wings, propellers, and fuselages; frame applications such as notebook computers and mobile phones; medical applications such as X-ray boxes and roof panels; flat speaker panels, Applications for audio products such as speaker cones, golf balls, faceplates, snowboards, water skateboards, guard boards (rugby, baseball, hockey, skis, etc.), sporting goods applications, board springs, windmill blades, elevators (frame panels, doors), etc. General industrial use. In addition, the board mentioned in the present invention is not only a flat board, but certainly also includes a board with curvature. the

fourth way

Hereinafter, the fourth aspect of the present invention will be described in detail, and descriptions of sentences, preferable manufacturing conditions, and the like will be described further. the

The fourth aspect provides an excellent method of producing a high-strength and excellent-looking fiber-reinforced composite material molded article in a short period of time using a compression molding method. the

(A molding material formed by impregnating substantially continuous reinforcing fibers with a thermosetting resin composition) 

As the reinforcing fiber that can be used in this aspect, the reinforcing fiber described in the third aspect can be used, and preferable examples thereof are also preferable in this aspect as well. the

The thermosetting resin composition used in the fourth aspect may be any known thermosetting resin as long as it can be used as a matrix resin of FRP, and epoxy resin, unsaturated vinyl ester resin, and bismaleimide resin can be suitably used. any of these. Among them, in consideration of the mechanical properties of molded products, epoxy resins having high mechanical properties after curing and excellent adhesion to reinforcing fibers can be most suitably used. the

In this form, instead of the above-mentioned molding material, a material formed by overlapping a material impregnated with a thermosetting resin to substantially continuous reinforcing fibers and a material having a thermosetting resin impregnated with short fiber-shaped reinforcing fibers on at least one side surface may be used. Forming material. As the material for impregnating short-fibrous reinforcing fibers with a thermosetting resin, a material in which reinforcing fibers cut into 12 to 50 mm, generally called SMC, are impregnated with the above-mentioned thermosetting resin can be suitably used. the

For materials impregnated with short-fibrous reinforcing fibers with thermosetting resin, since the orientation of the reinforcing fibers is irregular, compared with molding materials formed of only substantially continuous reinforcing fibers, FRP tends to have rib structures or protrusions along the line. The advantage of the complex shape of the structure, but the disadvantage of poor mechanical properties. Therefore, by compressing and molding both of them, it is possible to obtain FRP having a complex shape such as a rib structure or a convex structure, which has both advantages and superior mechanical properties. the

Here, as the thermosetting resin in the material obtained by impregnating short-fibrous reinforcing fibers with a thermosetting resin, the same resin as in the material obtained by impregnating substantially continuous reinforcing fibers with a thermosetting resin may be used, or a different resin may be used. the

(mold)

In the FRP manufacturing method of the fourth aspect, it is preferable to use a mold having a structure capable of holding the inside of the mold airtight when the mold is closed. In this method, the airtightness required for the mold means that a sufficient amount of molding material is placed in the mold to fill the mold, and the thermosetting resin constituting the molding material does not substantially leak out of the mold when pressurized. As a structure to keep the inside of the mold airtight, a shared edge structure (see Figure 2) or a rubber seal structure can be used for the parts where the upper mold and the lower mold (male and female molds) contact when the mold is closed. Any known structure may be used as long as it can hold the inside of the mold airtight. the

In addition, the air remaining inside the mold when the mold is closed may cause pinholes on the surface of the FRP and voids inside the FRP. , By using the degassing mechanism for degassing, the air remaining inside the mold can be effectively removed. the

As the degassing mechanism, an openable or closable hole (see FIG. 3 ) may be provided inside the mold to open to the outside of the mold, or a pump may be further provided to depressurize. Degassing is carried out by opening the holes at the moment when the entire inside of the mold is filled with the molding material, and closing them at the time of pressurization. the

Furthermore, after the molding of the FRP is completed, in order to take out the FRP easily, a mechanism for releasing the FRP, such as an ejector pin and an air valve (see FIG. 3 ), may be attached to the mold. As a result, the FRP can be easily removed without waiting for the mold to cool down, making it suitable for mass production. In addition, the mechanism for releasing the mold may be an ejector pin, an air valve, or other mechanisms, and may be any conventionally known mechanism. the

(Manufacturing method of FRP) 

A method of obtaining FRP using the above-mentioned molding material and mold will be described with reference to the drawings. the

Fig. 1A is a diagram showing a state in which a molding material is placed inside a mold before the mold is closed. In addition, 1 shown in several figures of this mode indicates a female mold, 2 indicates a male mold, 3 indicates a common edge structure, 4 indicates a hole that can be opened and closed, 5 indicates a tip (up and down by air), and 6 indicates a gasket , A represents the air inflow when the hole is open, and B represents the air inflow when the hole is closed. First, the temperature of the mold is adjusted to the curing temperature of the thermosetting resin of the molding material or higher, and then the molding material is placed in the mold. the

Subsequently, forming is carried out by closing the mold and pressing the forming material. 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 inside of the mold. the

As mentioned above, coil warping that occurs when compression molding a prepreg made of continuous reinforcing fibers is mainly due to excess flow of matrix resin. Therefore, in this form, it was found that in order to suppress the flow of the resin, a good effect can be obtained if a molding material having a surface area on one side close to the surface area on one side of the inside when the mold is closed (the surface area on one side of FRP) is used, Specifically, the ratio S ₁ /S 2 of the surface area S ₁ on _one side of the molding material formed by impregnating substantially continuous reinforcing fibers with a thermosetting resin to the surface area S _{2 on} one side inside the mold when the mold is closed can be 0.8 to 0.8. 1. If S ₁ /S ₂ is less than 0.8, the resin flow inside the mold will be intense, and coil bending will easily occur. On the other hand, when S ₁ /S ₂ exceeds 1, if the peripheral part of the molding material is exposed from the mold, it will cause difficulty in closing the mold or insufficient molding material in the molded product; if the molding material is folded, the fiber orientation will be disordered . Here, the single surface area is the surface area of one of two substantially equal surfaces constituting a molded article having a thickness gap.

In addition, especially in the case of obtaining high-quality FRP, it is also possible to use one close to the molded product (shape inside the mold when the mold is closed) in terms of volume and height of the molding material. The volume and thickness of the molding material put into the mold are preferably 100 to 120% of the volume and 100 to 150% of the thickness of the molded article, respectively. the

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

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

In this form, it is necessary to preliminarily adjust the temperature of the mold to the curing temperature of the thermosetting resin or higher. At this time, as long as the temperature for temperature adjustment is the curing temperature determined by the composition of the thermosetting resin or higher, a more preferable temperature can be selected according to the molding conditions other than the composition and temperature. the

In the FRP manufacturing method 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. It can be suitably determined according to the shape of FRP, etc. the

Example

Hereinafter, four aspects of the present invention will be specifically described based on examples. the

Embodiment of the first mode

In the present examples and comparative examples, substances represented by abbreviations below were used. The average particle diameter is a value measured by a laser diffraction scattering method. In addition, this aspect is not limited to the following Examples. the

<epoxy resin>

EP828: Japan Epoxy Co., Ltd. ェピコ-ト828 (registered trademark, bisphenol A epoxy resin, 120p/25℃)

EP807: Japan Epoxy Co., Ltd. ェピコ-ト807 (registered trademark, bisphenol F type epoxy resin, 30p/25℃)

EP604: ェピコ-ト604 (registered trademark, glycidylamine type epoxy resin) manufactured by Japan Epoxy Resin Co., Ltd.

N740: EPICLON N-740 (Novolac-type epoxy resin, semi-solid) manufactured by Dainippon Ink Chemical Industry Co., Ltd.

YCDN701: Tohto Chemical Co., Ltd. フェノト-トYCDN701 (cresol varnish type epoxy resin)

フレツプ50: Epoxy resin manufactured by Toray Polysulfide Rubber Co., Ltd., registered trademark

EXA1514: Dainippon Ink Chemical Industry Co., Ltd. EPICLON EXA1514 bisphenol S type epoxy resin

<Amine compound having at least one sulfur atom in the molecule>

DDS: Seikakuyua-S (Diaminodiphenylsulfone, registered trademark, sulfur atom content: 12.9% by mass) manufactured by Wakayama Seika Co., Ltd.

BAPS: Wakayama Seika Co., Ltd. BAPS (4,4'-diaminodiphenyl sulfide, sulfur atom content: 7.4% by mass)

BAPS-M: Wakayama Seika Co., Ltd. BAPS-M (bis(4-(3-aminophenoxy)phenyl)sulfone, sulfur atom content: 7.4% by mass) 

ASD: Wakayama Seika Co., Ltd. ASD (4,4'-diaminodiphenyl sulfide, sulfur atom content: 14.8% by mass)

TSN: Wakayama Seika Co., Ltd. TSN (o-toluidine sulfone, sulfur atom content: 11.7% by mass)

<urea compound>

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

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

<Dicyandiamide>

DICY7: Dicyandiamide (average particle size 7μm)

DICY15: dicyandiamide (average particle size 15μm)

DICY1400: dicyandiamide (average particle size 20μm)

<additive>

PVF: ビツレツク E (polyvinyl formal) manufactured by Chitsuso Co., Ltd.

YP50: 7ェノト-トYP50 manufactured by Tohto Chemical Co., Ltd.

Fumed silica: manufactured by Japan Acerosil Co., Ltd., Acerosil 300

(Evaluation method)

Using the resin composition of this embodiment, a prepreg was manufactured by the method described later, and its gel time, pot life, and mechanical properties were measured. The measurement method is as follows. the

(1) Gel time

A square sample with a side length of 2 mm is cut out from the prepreg and sandwiched between two glass coverslips. Place it on a heating plate controlled at 130°C±0.5°C. The instant after placing the sample was used as the gel time to determine the starting time. From time to time, the prepreg was pressed repeatedly with tweezers or the like to check the state of the epoxy resin composition, and the time until the gelation was completely completed was measured as the gel time. The complete gelation referred to here means a state in which the epoxy resin composition does not flow when pressed with tweezers or the like. the

(2) Available period

Put the prepreg in a constant temperature dryer at 30±1°C, observe the adhesion of the prepreg every day, up to 21 days, and take the number of days when the adhesion is lost (the prepregs are not bonded to each other) as available period. the

(3) Mechanical properties

The prepreg was molded by vacuum bag forming to produce a flat fiber-reinforced composite material of 200 mm in length x 200 mm in width x 150 mm in thickness. The 0° flexural strength and 90° flexural strength of the panels were determined according to ASTM D 790. the

(content of sulfur atoms)

When the A component does not have a sulfur atom, the sum of the added mass parts of the A component, C component, D component and additives is counted as X, and the mass part of the B-1 component used in the manufacture of the epoxy resin composition is counted is Y, and the content of sulfur atoms in the B-1 component used in the manufacture of the epoxy resin composition is defined as p (mass %), then the content S of sulfur atoms can be obtained from the following formula. the

S (mass%) = pY/(X+Y)

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

For this measurement sample, a high-frequency plasma emission analyzer (manufactured by Japan Jarel Ashish Co., Ltd., ICAP-575 MK-II) was used to measure the concentration of sulfur atoms by atomic absorption spectrometry (measurement conditions: plasma gas 0.8 L/ min, the cooling medium gas is 16L/min, the carrier gas is 0.48L/min, and the measurement wavelength is 180.7nm). The concentration of sulfur atoms in the aqueous solution was obtained using a previously prepared calibration curve, and the sulfur atom content (mass %) in the epoxy resin composition was calculated from the concentration of sulfur atoms. the

Embodiment 1～10

The composition ratio shown in Table 1 was mixed until uniform, and the epoxy resin composition was prepared. The epoxy resin composition was uniformly coated on release paper with a resin mass per unit area of 33.7 g/m ² using a simple roller coater to form a resin layer. This resin layer is attached to a sheet-shaped object formed by aligning carbon fibers (TR50S, tensile modulus of elasticity: 240GPa) manufactured by Mitsubishi Rayon Co., Ltd. in one direction so that the fiber basis weight is 125g/ ^m2 After both sides of the carbon fiber are heated and pressed with a roller at 100°C and a linear pressure of 2kg/cm, the epoxy resin composition is soaked into the carbon fiber, and the mass per unit area of the fiber is 125g/m ² (resin content is 35% by mass) ) of the prepreg.

The gel time at 130°C and the usable period of the prepregs obtained from the epoxy resin compositions of Examples 1 to 10 were evaluated. As a result, the gel times were all 200 seconds or less, and the usable period Adhesiveness can be maintained even after 21 days, so a usable period of 21 days or more can be confirmed. the

The physical properties of the flat composite material (FRP sheet material) also showed good physical properties, with the 0° bending strength exceeding 160 kg/mm ² and the 90° bending strength exceeding 10 kg/mm ² .

Examples 11-20

A prepreg was produced and evaluated in the same manner as in Example 1 except that the composition ratio shown in Table 2 was mixed until uniform. the

The prepregs obtained from the epoxy resin compositions of Examples 11 to 20 also had a gel time of 200 seconds or less, and a service life of 21 days or more was confirmed. the

The physical properties of the flat composite material (FRP sheet material) also showed good physical properties, with the 0° bending strength exceeding 160 kg/mm ² and the 90° bending strength exceeding 10 kg/mm ² .

Example 21

In the composition shown in Example 21 of Table 3, after mixing the epoxy resin of component B and the amine component (DDS) at room temperature, heating at 150°C to partially react, and adjusting the viscosity at 90°C to 30 to 90 Poise (B-2 component). This reactant, component A, and components C and D were mixed until uniform at the composition ratio shown in Example 21 of Table 3 to prepare an epoxy resin composition. The epoxy resin composition was uniformly coated on release paper with a resin mass per unit area of 33.7 g/m ² using a simple roller coater to form a resin layer. This resin layer is attached to a sheet-shaped object formed by aligning carbon fibers (TR50S, tensile modulus of elasticity: 240GPa) manufactured by Mitsubishi Rayon Co., Ltd. in one direction so that the fiber basis weight is 125g/ ^m2 After both sides of the carbon fiber are heated and pressed with a roller at 100°C and a linear pressure of 2kg/cm, the epoxy resin composition is soaked into the carbon fiber, and the mass per unit area of the fiber is 125g/m ² (resin content is 35% by mass) ) of the prepreg.

The gel time at 130°C and the usable period of the prepreg obtained from the epoxy resin composition of Example 21 were evaluated. As a result, the gel time was 200 seconds or less, and the usable period elapsed. Adhesiveness can be maintained even at 21 days, so a usable period of 21 days or more can be confirmed. the

The physical properties of the flat composite material (FRP sheet material) also showed good physical properties, with the 0° bending strength exceeding 160 kg/mm ² and the 90° bending strength exceeding 10 kg/mm ² .

Examples 22-31

After mixing the epoxy resin of A component and the amine component (DDS) at room temperature at the composition ratio shown in Table 3, it heated at 150 degreeC and reacted partly, and adjusted it so that the viscosity at 90 degreeC may be 30-90 poise. A prepreg was produced and evaluated in the same manner as in Example 21 except that the reactant, component B and component C were mixed until uniform at the composition ratio shown in Table 3. the

The prepregs obtained from the epoxy resin compositions of Examples 22 to 31 also had a gel time of 200 seconds or less, and a pot life of 21 days or more was confirmed. the

The physical properties of the flat composite material (FRP sheet material) also showed good physical properties, with the 0° bending strength exceeding 160 kg/mm ² and the 90° bending strength exceeding 10 kg/mm ² .

Examples 32-45

After mixing the epoxy resin of component A and the amine component at room temperature at the composition ratio shown in Table 4, heat at 150°C to partially react, and adjust the viscosity at 90°C to 30 to 90 poise. A prepreg was produced and evaluated in the same manner as in Example 21 except that the reactant, component B and component C were mixed until uniform at the composition ratio shown in Table 4. the

The prepregs obtained from the epoxy resin compositions of Examples 32 to 45 also had a gel time of 200 seconds or less, and a pot life of 21 days or more was confirmed. the

Comparative example 1～8

A prepreg was produced and evaluated in the same manner as in Example 1 except that the composition ratio shown in Table 5 was mixed until uniform. the

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

Comparative example 9～10

A prepreg was produced and evaluated in the same manner as in Example 21 except that the composition ratio shown in Table 3 was mixed until uniform. the

As a result, for Comparative Examples 9 and 10 that did not contain dicyandiamide, although the same amount as that of Example 21 and Example 24 was blended as the total amount of curing agent, the flat composite material produced in each Example In contrast, only flat composite materials with a 0° bending strength about 10% lower can be obtained. Furthermore, in Comparative Example 10, the prepreg whose usable period was as short as 5 days or less was obtained. the

As explained in detail above, the epoxy resin composition of the present embodiment can be cured in a short time at a relatively low temperature. Therefore, the prepreg obtained by using the epoxy resin composition has a sufficient pot life even when stored at room temperature, and the effect that the composite material obtained from the prepreg exhibits excellent mechanical properties can be obtained. Furthermore, it was proved that the use of this prepreg can shorten the processing time in the molding of the fiber-reinforced composite material, so that it can be manufactured at low cost. the

Example of the second way

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

As raw materials of the thermosetting resin composition, the following epoxy resin and curing agent were prepared. the

<epoxy resin>

EP828:

Liquid bisphenol A epoxy resin manufactured by Japan Epoxy Co., Ltd., ェピコ-ト828 (registered trademark)

EP1009:

Solid bisphenol A epoxy resin manufactured by Japan Epoxy Co., Ltd., ェピコ-ト1009 (registered trademark)

AER4152:

Epoxy resin manufactured by Asahi Kasei Corporation, アラルダイト AER4152 (registered trademark)

N740:

Dainippon Ink & Chemicals Co., Ltd. novolak-type epoxy resin, Epicron N-740 (registered trademark)

<curing agent>

HX3722:

Microcapsule latent curing agent manufactured by Asahi Kasei Co., Ltd., ノバキユア HX3722 (registered trademark)

FXE1000:

Latency curing agent for epoxy resin manufactured by Fuji Chemical Co., Ltd., 7jikua FXE1000

PDMU:

PTI Japan Co., Ltd. Phenyl dimethyl urea, タキユア94 (registered trademark)

DCMU:

3,4-dichlorophenyl-N,N-dimethylurea manufactured by Hodo Ketani Chemical Co., Ltd., DCMU99

Dicy:

Dicyandiamide produced by Japan Epoxy Co., Ltd., Dicy7

2P4MZ:

2-Phenyl-4-methylimidazole manufactured by Shikoku Chemicals Co., Ltd.

<Viscosity measurement>

Device: RDS-200 manufactured by Rheometrics

Measuring mode: parallel plate (25mmφ, interval 0.5mm)

Frequency: 1Hz

Temperature setting: from 50°C to 10°C/min, measure the isothermal viscosity after reaching 120°C

Measurement data: the viscosity at 50°C, the time until the cut-off viscosity exceeds 10 ² Pa·sec after reaching 120°C. In this example, it was confirmed that all the thermosetting resin compositions had viscosities up to 120° C. of 10 ¹ Pa·sec or less.

<30°C × Viscosity increase after 3 weeks>

Immediately after preparing the thermosetting resin composition, samples were taken, and the viscosity η ₀ at 50°C was measured by the above-mentioned viscosity measurement method. The same thermosetting resin composition was left in a dryer at 30°C for 3 weeks. After the heating process, the same Viscosity measurement was carried out to measure the viscosity η ₁ at 50°C. The viscosity increase was determined by η ₁ /η ₀ .

<Prepreg preparation>

The temperature of the thermosetting resin composition was raised to 50° C. to lower the viscosity, and then thinly coated on a release paper to prepare a hot-melt film. The hot-melt film was impregnated into carbon fiber fabric TR3110 manufactured by Mitsubishi Rayon Corporation to obtain a prepreg. The resin content was adjusted to 30% by mass. the

<forming>

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

<Mechanical property measurement>

Using a universal testing machine manufactured by Instron, the flexural test was performed according to ASTM D2344 according to ASTM D790. Interlaminar shear test (ILSS). the

Example 46-50

The thermosetting resin composition was prepared with the composition shown in Table 6, and the viscosity measurement at 50 degreeC and the viscosity measurement at 50 degreeC after 30 degreeC x 3 weeks were performed. The time until the viscosity exceeds 10 ² Pa·sec after reaching 120°C was measured. Manufactured prepregs are evaluated for operability by hand feel. Those with suitable viscosity and drapability and easy handling were marked as "○", and those that were difficult to handle were marked as "×". Then, the prepared prepreg was left to stand at 30° C. for 3 weeks, and the subsequent handleability was similarly evaluated. Furthermore, a prepreg is molded by the method mentioned above. Molding was carried out under three conditions of 120°C x 15 minutes, 120°C x 10 minutes, and 140°C x 4 minutes, and the mechanical properties were measured respectively. The summarized results are shown in Table 6. In the thermosetting resin composition shown in the Example, the handleability of the prepreg immediately after preparation, and the handleability of the prepreg after 3 weeks after preparation at 30 degreeC were favorable. The surface appearance after molding was also beautiful, and the mechanical properties were also good.

Comparative Example 13 (Example with low viscosity at 50°C)

A thermosetting resin composition was prepared with the composition shown in Table 7. Since the viscosity at 50°C is less than 5×10 ¹ Pa·sec, the prepreg immediately after preparation is very viscous and sticky, making it difficult to handle.

Comparative Example 14 (Example with high viscosity at 50°C)

A thermosetting resin composition was prepared with the composition shown in Table 7. Since the viscosity at 50° C. exceeds 1×10 ⁴ Pa·sec, the thermosetting resin composition is very hard and cannot be thinned.

Comparative Example 15 (30°C x 3 weeks later, the viscosity increased by more than 2 times)

A thermosetting resin composition was prepared with the composition shown in Table 7. The thermosetting resin composition after 30°C x 3 weeks was very hard, and the viscosity could not be measured. In addition, although the handleability of the prepreg immediately after preparation was good, it hardened after standing at room temperature for 3 weeks, and it reached the end of life. the

Comparative Example 16 (an example in which the arrival time of 10 ⁶ Pa·sec at 120°C exceeds 1000 seconds)

A thermosetting resin composition was prepared with the composition shown in Table 7. The arrival time of 10 ⁶ Pa·sec at 120° C. was as long as 1300 seconds, and it was clearly found that the curability was poor compared with Examples. In addition, since there was no fracture in the bending test, it was rated as "unable to measure".

As described above, the thermosetting resin composition of this embodiment can provide a thermosetting resin composition suitable for a matrix resin of a prepreg having good handleability at room temperature and long life at room temperature and maintaining molding In addition to excellent physical properties, high-speed forming required for industrial applications is possible. the

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

From the above, it can be proved that the thermosetting resin composition, prepreg, and FRP production method of this embodiment are all very suitable for high-speed molding, and greatly contribute to the reduction of molding processing costs, which is the biggest drawback of FRP. the

Example of the third way

Hereinafter, the third aspect of the present invention will be specifically described by way of examples. In addition, this aspect is not limited to the following Examples. the

[Example based on resin composition (1)]

Examples 1 to 20 shown in the first aspect satisfy the conditions required in this aspect. The excellent results shown in Examples 1 to 20 are as described in the examples of the first aspect, thus proving that the epoxy resin composition and prepreg provided by this aspect have excellent characteristics. In addition, Comparative Examples 1 to 8 shown in the first aspect did not satisfy the conditions required in the present aspect. From this, it was proved that none of Comparative Examples 1 to 8 could exhibit such excellent characteristics as Examples 1 to 20. the

Example 51

The epoxy resin composition obtained in Example 3 of the first embodiment was uniformly coated on a release paper with a resin mass per unit area of 26.8 g/m ² on a release paper using a simple roll coater to form a resin layer. This resin layer is bonded to a sheet-shaped object formed by aligning carbon fibers (TR50S, tensile modulus of elasticity: 240GPa) manufactured by Mitsubishi Rayon Co., Ltd. in one direction so that the mass per unit area of the fibers is 125g/ ^m2 After the two sides of the carbon fiber are heated and pressed with a roller at 100°C and a linear pressure of 2kg/cm, the epoxy resin composition is soaked into the carbon fiber, and the mass per unit area of the fiber is 125g/m ² (resin content is 30% by mass) ) of the prepreg.

On the other hand, the epoxy resin composition obtained in Example 3 was evenly coated on the release paper with a resin mass per unit area of 164 g/m ² using a simple roller coater to form a resin layer. The resin layer was bonded to carbon fiber fabric TR3110 (a fabric formed by plain weaving TR30S3L (the number of filaments is 3000) with a weaving density of 12.5 threads/inch (the mass per unit area is 200 g/ ^m2 ) manufactured by Mitsubishi Rayon Co., Ltd. )) After heating and pressing with a roller at 100°C and a linear pressure of 2kg/cm on one surface, the epoxy resin composition is soaked into the carbon fiber, and the mass per unit area of the fiber is 200g/m ² (resin content is 45 mass%) fabric prepreg.

Cut the prepreg and fabric prepreg into 200×200mm, the prepreg is 0°/90°/0°/90°/0°/90°/0°/90°/0°/ 90°/0°/90°/0°/90°/0°/90° laminated 16 pieces of prepreg in total, and then laminated 1 piece of fabric prepreg on it (on the 0° layer) to prepare Prepreg laminate. the

Heat a 220×220mm metal mold (the surface of the metal mold that can be used is 210×210mm) with a 10mm wide and 3mm thick butyl rubber gasket placed in an L shape on 2 of the 4 sides to 130°C. the

The previously prepared prepreg laminate was placed on the usable part of the mold at a distance of 5 mm from the end of the mold or the gasket made of butyl rubber. And, the metal mold was immediately closed and a pressure of 10 kg/cm ² was applied for 15 minutes to obtain an FRP sheet.

Three test pieces of 30×30 mm were randomly cut out from the FRP plate, and the volume content of carbon fibers was determined (Archimedes method), and the average was 60.6 volume%. The resin content was 30.9% by weight when the density of the matrix resin was 1.25 and the average density of carbon fibers was 1.82. the

The obtained FRP sheet had sporadic irregularities due to damage on the surface of the metal mold, and the centerline average roughness of the portion without irregularities was measured with the device and method described in the detailed description, and the result was 0.27 μm. the

As described above, it has been demonstrated that the present method can provide an FRP sheet material suitable as an outer panel of a vehicle or an industrial machine, and a prepreg suitable for obtaining an FRP sheet material. the

Embodiment of the fourth mode

The fourth aspect of the present invention will be specifically described below by way of examples. In addition, this aspect is not limited to the following Examples. the

Example 52

As a structure to keep the inside of the mold airtight, the part where the upper mold and the lower mold contact when the mold is closed adopts a common edge structure (see Fig. 2), and the surface area of the thickness part except the FRP part of the lower mold is ^900cm2 . The upper mold and the lower mold are heated to 140°C at the same time.

As a molding material, a prepreg TR390E125S (manufactured by Mitsubishi Rayon Co., Ltd.) impregnated with carbon fibers aligned in one direction was cut into 285×285 mm, and the orientation direction of the fibers was 0 A material obtained by laminating 18 sheets (thickness: 2 mm, total volume: 162 cm ³ , single surface area: 812 cm ² ) alternately at 90° and 90°. S ₁ /S ₂ is 812/900=0.9. In addition, the epoxy resin used for the prepreg TR390E125S is an epoxy resin composition corresponding to the epoxy resin composition of 1st aspect manufactured by the following manufacturing method.

That is, 15 parts by mass of EP828, 6 parts by mass of PDMU, and 9 parts by mass of dicyandiamide were added to 100 parts by mass of a resin composition obtained by reacting a mixture of EP828 and DDS (92:8 in mass ratio) at 150° C. Mix until a homogeneous epoxy composition. the

Place the above-mentioned molding material on the lower mold, and immediately lower the upper mold to close the mold. After applying a pressure of 9.8×10 ² KPa for 10 minutes, open the mold and keep the temperature of the mold at 140°C. A molded product (thickness: 1.6 mm, volume: 144 cm ³ ) was taken out. The molded product has no pinholes and voids on the surface, back and cross section, and has an excellent appearance.

Example 53

As the molding material, a molding material (total ^thickness of 4mm and a total volume of 325cm ³ ). S ₁ /S ₂ is 0.9.

Place the above-mentioned molding material on the lower mold, and immediately lower the upper mold to close the mold. After applying a pressure of 3.0×10 ³ kPa for 10 minutes, open the mold and keep the temperature of the mold at 140°C. A molded product (thickness 3.2 mm, volume 288 cm ³ ) was taken out. The molded product was of a grade having no problems in appearance and physical properties even on the surface.

As described above, it has been proved that by using the method for producing FRP of this embodiment, FRP composed of substantially continuous reinforcing fibers having high strength and excellent appearance can be obtained by using a compression molding method suitable for mass production. the

Comparative Example 17

In addition to using a prepreg TR390E125S (manufactured by Mitsubishi Rayon Co., Ltd.) impregnated with carbon fibers aligned in one direction and impregnated with an epoxy resin composition as a molding material. Molding was carried out under the same conditions as in Example 1, except that 24 sheets (thickness: 2.6 mm, total volume: 162 cm ³ , single surface area: 625 cm ² ) were stacked alternately at 90° and 90°. S ₁ /S ₂ is 625/900=0.7.

In the molded product, the fiber orientation is greatly disturbed by the flow of the resin during molding, and the disorder in the outer peripheral portion is particularly remarkable. the

Comparative Example 18

In addition to using a prepreg TR390E125S (manufactured by Mitsubishi Rayon Co., Ltd.) impregnated with carbon fibers aligned in one direction and impregnated with an epoxy resin composition as a molding material, cut to 320×320mm, and then making the orientation direction of the fibers 0 14 sheets (1.6 mm in thickness, 162 cm ³ in total volume, and 1,024 cm ² in surface area on one side) were laminated in such a manner that 14 sheets were stacked alternately at 90° and 90°, and molded under the same conditions as in Example 1. S ₁ /S ₂ is 1024/900=1.1.

During molding, since the reinforcing fibers constituting the molding material are exposed from the mold, the fibers are pulled out, and the fiber orientation is disturbed. Therefore, the obtained molded product had poor appearance, and a product with a smooth surface could not be obtained. the

Possibility of industrial use

According to the present invention, it is possible to easily provide a prepreg which is endowed with a quantitative index, can be cured in a relatively low temperature in a short time, has excellent mechanical properties, and can be stored at room temperature for a long time, and a lightweight, high-strength, high-strength prepreg. Rigid FRP. It can be widely applied from sports and leisure use to industrial use such as automobile and aircraft. the

Claims (8)

1. the manufacturing approach of a formed product of fiber-reinforced composite material, it comprises the steps:

Prepare the step of shaping dies and prepreg; This shaping dies has common edge structure or the rubber sealing structure that keeps sealing; And constituted by mold and bed die, the mould inside when close die has the long-pending S of being of monoplanar surface of one of thickness 2 equal in fact faces at interval ₂,

Said prepreg is the prepreg that substantially soaks into composition epoxy resin on the continuous reinforcing fiber; Said composition epoxy resin has following A composition, B composition, C composition and D composition to constitute; The content of sulphur atom in the composition epoxy resin and C composition is respectively 0.2～7 quality % and 1～15 quality %

A composition: epoxy resin

The B composition: the B-1 composition, have the amines and/or the B-2 composition of at least one sulphur atom in the molecule, have the reaction product of the amines of at least one sulphur atom in epoxy resin and the molecule

C composition: urea compounds

D composition: dicyandiamide

The long-pending S of being of monoplanar surface with one of thickness 2 equal in fact faces at interval of this prepreg ₁Single face satisfy S ₁/ S ₂=0.8～1;

With the solidification temperature of said shaping dies temperature adjustment in advance to said epoxy resin or the step more than it;

Said prepreg is put into this step of the shaping dies of temperature adjustment; And

Closed shaping dies carries out compression molding, makes prepreg be full of the inner step of whole shaping dies.

2. the manufacturing approach of formed product of fiber-reinforced composite material according to claim 1; Wherein, continuous reinforcing fiber is in fact soaked into composition epoxy resin and the volume of the prepreg that forms and volume that thickness is respectively formed products 100～120% with 100～150% of thickness.

3. the manufacturing approach of formed product of fiber-reinforced composite material according to claim 1, wherein, close die is full of entire die when inner at prepreg, uses deaerating mechanism to outgas.

4. the manufacturing approach of formed product of fiber-reinforced composite material according to claim 1 wherein, does not reduce the temperature of mould and just takes out formed product of fiber-reinforced composite material.

5. the manufacturing approach of formed product of fiber-reinforced composite material according to claim 1 wherein, as mould, is used the mould with the mechanism that makes the formed product of fiber-reinforced composite material demoulding.

6. the manufacturing approach of formed product of fiber-reinforced composite material according to claim 1, wherein, fortifying fibre is a carbon fiber.

7. according to the manufacturing approach of any described formed product of fiber-reinforced composite material in the claim 1～6; Wherein, Replacement is soaked into composition epoxy resin to continuous reinforcing fiber in fact and the prepreg that forms; As moulding material, use to have fortifying fibre to the short fiber shape to the material that continuous reinforcing fiber is in fact soaked into composition epoxy resin and at least one side surface and soak into the moulding material that the material of composition epoxy resin overlaps.

8. the manufacturing approach of formed product of fiber-reinforced composite material according to claim 1, wherein, said prepreg be shaped as the shape that when shaping dies cuts out, is contained in the shaping dies.

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