阅读说明：本技术 纤维增强成型品及其制造方法 (Fiber-reinforced molded article and method for producing same ) 是由 冈英树 铃木温久 于 2019-01-28 设计创作，主要内容包括：本发明提供在拉拔纤维增强成型品的制造中,抑制附着残留在模具内面的树脂残渣物的产生而可以高速且连续地拉拔成型的手段。一种纤维增强成型品的制造方法,是使环氧树脂组合物含浸于由增强纤维束集束而成的增强纤维束集合体中,在使得到的树脂含浸纤维基材从拉拔成型区域通过的同时,使上述环氧树脂组合物加热固化,而拉拔成型为规定形状的纤维增强成型品的制造方法,上述环氧树脂组合物至少包含以下的成分A～D。A：氨基酚型环氧树脂。B：具有纳迪克酸酐结构的酸酐和具有邻苯二甲酸酐的氢化物结构的酸酐。C：选自硅化合物、镁化合物、钙化合物、铝化合物和无机碳中的至少一种、且莫氏硬度为3以下的填料。D：脱模剂。(The invention provides a means for suppressing the generation of resin residues adhered to and remained on the inner surface of a die in the production of a drawn fiber reinforced molded product and continuously drawing and molding at high speed. A process for producing a fiber-reinforced molded article, which comprises impregnating a reinforcing fiber bundle assembly comprising a plurality of reinforcing fiber bundles with an epoxy resin composition, and subjecting the epoxy resin composition to heat curing while passing the resin-impregnated fiber base material through a draw molding region to draw-mold the fiber-reinforced molded article into a predetermined shape, wherein the epoxy resin composition comprises at least the following components A to D. A: an aminophenol type epoxy resin. B: an acid anhydride having a nadic anhydride structure and an acid anhydride having a hydride structure of phthalic anhydride. C: at least one filler selected from the group consisting of silicon compounds, magnesium compounds, calcium compounds, aluminum compounds, and inorganic carbon, and having a Mohs hardness of 3 or less. D: and (3) a release agent.)

1. A fiber-reinforced molded article obtained by impregnating an epoxy resin composition into a reinforcing fiber bundle assembly comprising a plurality of reinforcing fiber bundles and curing the epoxy resin composition,

the epoxy resin composition at least comprises the following components [ A ], [ B ], [ C ] and [ D ],

and the component [ A ] is 60 to 100 parts by mass based on 100 parts by mass of the total epoxy resin contained in the epoxy resin composition,

[A] the method comprises the following steps An epoxy resin of the aminophenol type which,

[B] the method comprises the following steps The following 2 types of acid anhydrides are mentioned,

[B1] the method comprises the following steps An acid anhydride having a nadic anhydride structure,

[B2] the method comprises the following steps An acid anhydride having a hydride structure of phthalic anhydride,

[C] the method comprises the following steps A filler which is at least one member selected from the group consisting of a silicon compound, a magnesium compound, a calcium compound, an aluminum compound and inorganic carbon and has a Mohs hardness of 3 or less,

[D] the method comprises the following steps And (3) a release agent.

2. The fiber-reinforced molded article according to claim 1, wherein the phthalic anhydride in the component [ B2] has a hydride structure, and has a structure of tetrahydrophthalic anhydride or a structure of hexahydrophthalic anhydride.

3. The fiber-reinforced molded article according to claim 1 or 2, wherein the component [ B1] is methylnadic anhydride, or

The component [ B2] is tetrahydromethylphthalic anhydride or hexahydromethylphthalic anhydride.

4. The fiber-reinforced molded article according to any one of claims 1 to 3, wherein in the epoxy resin composition,

100 parts by mass of the component [ B ] comprises 50 to 90 parts by mass of the component [ B1] and 50 to 10 parts by mass of the component [ B2],

the content of the component [ B ] is 50 to 200 parts by mass per 100 parts by mass of the component [ A ].

5. The fiber-reinforced molded article according to any one of claims 1 to 4, wherein in the epoxy resin composition,

the component [ C ] is a particulate talc,

the average particle diameter defined by the measurement result of the laser diffraction particle size distribution meter is 2 to 7 μm.

6. The fiber-reinforced molded article according to any one of claims 1 to 5, wherein in the epoxy resin composition,

the component [ D ] is contained in an amount of 0.1 to 8 parts by mass per 100 parts by mass of the component [ A ].

7. The fiber-reinforced molded article according to any one of claims 1 to 6, wherein in the epoxy resin composition,

further comprising 0.1 to 5 parts by mass of an imidazole derivative as a component [ E ] per 100 parts by mass of the component [ A ].

8. A process for producing a fiber-reinforced molded article, which comprises impregnating a reinforcing fiber bundle assembly comprising reinforcing fiber bundles with an epoxy resin composition, passing the resulting resin-impregnated fiber base material through a draw molding zone, and simultaneously heating and curing the epoxy resin composition to draw-mold the fiber-reinforced molded article into a predetermined shape,

the epoxy resin composition at least comprises the following components [ A ], [ B ], [ C ] and [ D ],

and the component [ A ] is 60 to 100 parts by mass based on 100 parts by mass of the total epoxy resin contained in the epoxy resin composition,

[A] the method comprises the following steps An epoxy resin of the aminophenol type which,

[B] the method comprises the following steps The following 2 types of acid anhydrides are mentioned,

[B1] the method comprises the following steps An acid anhydride having a nadic anhydride structure,

[B2] the method comprises the following steps An acid anhydride having a hydride structure of phthalic anhydride,

[C] the method comprises the following steps A filler which is at least one member selected from the group consisting of a silicon compound, a magnesium compound, a calcium compound, an aluminum compound and inorganic carbon and has a Mohs hardness of 3 or less,

[D] the method comprises the following steps And (3) a release agent.

9. A method for producing a fiber-reinforced molded article, which comprises impregnating a reinforcing fiber bundle assembly comprising bundles of reinforcing fibers with a thermosetting resin composition, passing the resin-impregnated fiber base material through a draw molding zone, and simultaneously heating and curing the thermosetting resin composition to draw-mold the resin-impregnated fiber base material into a predetermined shape,

a drawing forming die with an inlet part and an outlet part and a post-curing furnace are at least arranged in the drawing forming area,

performing the following steps in the drawing forming area: introducing the resin-impregnated fiber base material from an inlet of the draw-molding die, passing the resin-impregnated fiber base material through the die, and then, introducing the resin-impregnated fiber base material from an outlet of the die, and then, passing the resin-impregnated fiber base material through the post-curing furnace,

the drawing region satisfies the following conditions (i) to (v),

(i) when the mold temperature of the drawing is Tp and the in-mold residence time obtained by dividing the passage length of the resin-impregnated fiber base material in the mold, i.e., the mold passage length, by the molding speed is H, the following equations (1) to (3) are satisfied, wherein the unit of the mold temperature Tp is, the unit of the mold passage length is m, the unit of the molding speed is m/min, and the unit of the in-mold residence time H is min,

230-100H is more than or equal to Tp is less than or equal to 252-80H formula (1)

Tp is more than or equal to 180 and less than or equal to 245 formula (2)

H is more than or equal to 0.1 and less than or equal to 0.9 formula (3)

(ii) The thermosetting resin composition is kept in a liquid state at an inlet portion of the drawing die,

(iii) inside the mold, the thermosetting resin composition is changed from a liquid state to a gelled state,

(iv) the thermosetting resin composition is kept in a gelled state with a curing degree of 33 to 80% at the outlet of the mold,

(v) in the post-curing oven, the thermosetting resin composition is in a cured state with a degree of cure of 95% or more.

10. The method of producing a fiber-reinforced molded article according to claim 9, wherein a region in the mold where the thermosetting resin composition starts to be converted into a gelled state is located in a region having a length of 10 to 50% from the mold exit with respect to the mold passage length.

11. The method for producing a fiber-reinforced molded article according to claim 8 to 10, wherein the resin-impregnated fiber base material is heated in the post-curing furnace without contacting a heating element.

12. The method for producing a fiber-reinforced molded article according to any one of claims 1 to 11, which is used for a core for electric wire and cable.

Technical Field

The present invention relates to a fiber-reinforced molded article comprising a resin composition and a method for producing the same.

Background

Fiber-reinforced resins composed of reinforcing fibers such as carbon fibers and glass fibers and thermosetting resins such as epoxy resins and phenol resins are lightweight, but have excellent mechanical properties such as strength and rigidity, and excellent properties such as heat resistance and corrosion resistance, and therefore are used in various fields such as aviation, aerospace, automobiles, railway vehicles, ships, civil engineering and construction, and sporting goods. In particular, in applications requiring high performance, the following are used: a fiber-reinforced resin using continuous reinforcing fibers. Carbon fibers having excellent specific strength and specific elastic modulus are used as the reinforcing fibers, and a thermosetting resin is used as the matrix resin. As the thermosetting resin, an epoxy resin having excellent adhesion to carbon fibers is often used.

As a method for producing a fiber-reinforced Resin, a prepreg method, a hand lay-up method, a filament winding method, a drawing (pultrusion) method, an RTM (Resin Transfer Molding) method, or the like is appropriately selected and applied.

The drawing molding method often employs the following method.

A reinforcing fiber bundle in which several thousands to several tens of thousands of filaments are arranged in one direction is passed through a resin bath containing a liquid matrix resin, and the reinforcing fiber bundle is impregnated with the matrix resin. Then, the reinforcing fiber bundles impregnated with the matrix resin are passed through an extrusion die and a heating die, and the reinforcing fiber bundles impregnated with the matrix resin are continuously drawn by a drawing machine and cured.

In order to perform the drawing with good productivity, it is important to continuously and stably pass through the step. In the case where the molded article obtained is a molded article having a smooth surface, in order to smoothly draw the molded article from the inside of the mold, it is necessary to bring the molded article into close contact with the mold or to press the molded article with an appropriate pressure until the resin impregnated in the reinforcing fiber bundles is sufficiently cured.

The matrix resin used for the draw molding needs to have a sufficiently low viscosity for rapidly impregnating the reinforcing fibers in the resin impregnation tank, and also, from the viewpoint of continuous productivity for a long time, stability of the viscosity and further heat resistance of the cured product according to the intended product are important factors.

However, when a material obtained by impregnating reinforcing fiber bundles with a matrix resin (hereinafter referred to as a "resin-impregnated fiber base material") is continuously drawn in a drawing die and is heat-cured, the matrix resin is cured from a liquid state to a solid state, and thus, curing shrinkage of the matrix resin occurs. In this case, a part of the matrix resin may be adhered to and remain on the inner surface of the drawing die. This is a resin residue called fouling. If the fouling occurs, the drawing stress may increase. Further, if the drawing is stopped in the middle and the drawing is moved again, although the dirt is discharged, the properties of the part of the resin-impregnated fiber base material that is merely stopped and the other parts may change, or continuous molding may be difficult.

In particular, when a fiber-reinforced resin is used for a wire/cable core, the wire/cable is an extremely long conductive wire, and the product cross-sectional area of the wire/cable core is small, so that it is important to reduce the cost, suppress the generation of dirt, and increase the drawing speed. In order to suppress the occurrence of the fouling, improvement of curing conditions in a mold, improvement of a thermosetting resin composition, and the like have been performed.

For example, patent document 1 (claims, specification 0055) discloses an epoxy resin composition containing a phenol novolac type epoxy resin, an aminophenol type epoxy resin and/or a tetraglycidyl amine type epoxy resin as an epoxy resin, and methylnadic anhydride as an acid anhydride. Further, there is described a method of producing a molded article by charging the resin composition into a raw material tank at 25 ℃, impregnating the resin by drawing carbon fibers through the raw material tank containing the resin composition, inserting the impregnated resin into a circular mold, curing the resin by heating at 180 ℃ for 0.8min, and curing the resin after heating at 210 ℃ for 3 min. In addition, in example (specification 0093), there is described an epoxy resin composition in which 50% by mass of an aminophenol type epoxy resin is used as an epoxy resin, and 50/50 mass% of methylnadic anhydride and methyltetrahydrophthalic anhydride is blended. The matrix epoxy resin composition has a low viscosity, and can be impregnated into a reinforcing fiber sufficiently, so that the resulting molded article has high heat resistance.

Patent document 2 (claims, specification 0018) discloses an epoxy resin composition containing [ a ] an epoxy resin having 2 or more functions and containing an aromatic ring, [ B ] phthalic anhydride, and [ C ] at least one acid anhydride selected from the group consisting of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. Also disclosed is a molded article which can achieve both high tensile strength and heat resistance.

Further, patent document 3 (claims) describes an epoxy resin composition containing an aromatic ring-containing 2-or more-functional epoxy resin and an acid anhydride curing agent. It is disclosed that a molded article having both heat resistance and tensile strength at a high level can be obtained.

Next, focusing attention on a draw molding apparatus, patent document 4 (specification 0039, fig. 1) describes a molding apparatus including 3 dies, i.e., a 1 st die, a 2 nd die, and a 3 rd die, which draw a fiber filament impregnated with a thermosetting resin composition into the dies, in which the curing temperature can be independently controlled, and a difference in temperature range is provided between the dies. In this document (specification 0041), it is described that the degree of curing of the fiber-reinforced resin composition can be increased by heating thereafter while suppressing gelation near the inlet by dividing the heating region into 2 or more stages.

Further, patent document 5 (specification 0027) describes a drawing step. In which it is described: preferably the mold temperature is about 100-250 ℃, the temperature is lowered at the entrance of the mold and raised in stages towards the rear of the mold until the curing temperature is reached; post-curing is performed at 130 to 150 ℃ even if the resin is not completely cured during passage from the mold. It is also demonstrated that the insufficient curing of the matrix resin in the final product can be eliminated and the speed of the drawing can be increased.

Patent document 6 (claims) discloses a continuous drawing method in which a woven fabric sheet impregnated with a resin composition is heated to partially react an epoxy resin with a curing agent to increase the viscosity of the resin composition and is further gelled by heat or pressure, and further discloses a drawing method in which the partial reaction is carried out until the viscosity reaches a range of 1000 to 10000mpa.s, the gelling is carried out until the degree of curing reaches 40% to 75%, and the curing is further carried out by heat until the degree of crosslinking reaches 90% or more. In this document, a substance comprising at least one epoxy resin as a tri-or tetrafunctional epoxy resin, and (ii) a curing agent system comprising at least two reactive groups having different reactivities is disclosed as an epoxy resin composition.

Disclosure of Invention

Problems to be solved by the invention

However, the structure of patent document 1 has a problem in heat resistance of the obtained molded article. Further, since solidification shrinkage occurs while the mold is in a solid state, it is difficult to completely suppress fouling with this configuration.

The epoxy resin composition of patent document 2 is produced by a liquid process such as a filament winding method, and mainly aims to improve impregnation into a reinforcing fiber bundle. This configuration also makes it difficult to completely suppress fouling.

In the configuration of patent document 3, if methyl nadic anhydride is used alone as the acid anhydride curing agent, there is a problem of low viscosity for improving impregnation into the reinforcing fiber bundles. Further, if hydrogen phthalic anhydride is used alone, heat resistance is problematic. In addition, this configuration also makes it difficult to completely suppress fouling.

The method of patent document 4 aims to avoid the problem that the fiber-reinforced resin composition is easily drawn in an uncured state and to suppress the occurrence of defects such as cracks and warpage in a molded article due to rapid occurrence of a curing reaction. This configuration also makes it difficult to completely suppress the generation of fouling.

The method of patent document 5 is premised on curing a thermosetting matrix resin while continuously drawing the resin through a die. The post-curing is used for the purpose of enhancing the curing of a resin in a state in which the complementary curing is not completely performed and is not sufficiently cured. That is, in this method, since solidification shrinkage occurring when the mold is changed to a solid state occurs during the passage of the mold, it is difficult to completely suppress the occurrence of fouling.

The epoxy resin composition used in the method of patent document 6 uses a curing agent containing at least two reactive groups having different reactivity, and therefore, the variation in the degree of curing is large and the control of the reaction becomes complicated. Therefore, it is difficult to perform the drawing stably at a high speed. Further, it is difficult to completely suppress the occurrence of the solidification shrinkage during the passage of the mold and the occurrence of the fouling.

In view of the problems of the prior art, the present invention is to suppress the generation of resin residue called "fouling" which is a residue of resin, which is left as a part of a resin component attached to and remained on an inner surface of a drawing die when a thermosetting resin composition is solidified from a liquid state to a solid state, in a process for producing a fiber-reinforced molded product in drawing. This can prevent the increase of drawing force during the production process, and can perform drawing at high speed and continuously.

Means for solving the problems

In order to solve the above problems, a fiber-reinforced molded article according to the present invention has the following configuration.

A fiber-reinforced molded article obtained by impregnating an epoxy resin composition into a reinforcing fiber bundle assembly comprising a plurality of reinforcing fiber bundles and curing the epoxy resin composition,

the epoxy resin composition at least comprises the following components [ A ], [ B ], [ C ] and [ D ],

and the component [ A ] is 60 to 100 parts by mass relative to 100 parts by mass of all the epoxy resins contained in the epoxy resin composition.

[A] The method comprises the following steps Aminophenol type epoxy resin

[B] The method comprises the following steps The following 2 acid anhydrides

[B1] The method comprises the following steps Acid anhydride having nadic anhydride structure

[B2] The method comprises the following steps Acid anhydride having hydride structure of phthalic anhydride

[C] The method comprises the following steps At least one filler selected from the group consisting of silicon compounds, magnesium compounds, calcium compounds, aluminum compounds and inorganic carbon, and having a Mohs hardness of 3 or less

[D] The method comprises the following steps Release agent

In order to solve the above problem, a method for producing a fiber-reinforced molded article according to the present invention has the following configuration.

A process for producing a fiber-reinforced molded article, which comprises impregnating a reinforcing fiber bundle assembly comprising bundles of reinforcing fibers with an epoxy resin composition, passing the resulting resin-impregnated fiber base material through a draw molding zone, and simultaneously heating and curing the epoxy resin composition to draw-mold the fiber-reinforced molded article into a predetermined shape,

the epoxy resin composition at least comprises the following components [ A ], [ B ], [ C ] and [ D ],

and the component [ A ] is 60 to 100 parts by mass relative to 100 parts by mass of all the epoxy resins contained in the epoxy resin composition.

[A] The method comprises the following steps Aminophenol type epoxy resin

[B] The method comprises the following steps The following 2 acid anhydrides

[B1] The method comprises the following steps Acid anhydride having nadic anhydride structure

[B2] The method comprises the following steps Acid anhydride having hydride structure of phthalic anhydride

[C] The method comprises the following steps At least one filler selected from the group consisting of silicon compounds, magnesium compounds, calcium compounds, aluminum compounds and inorganic carbon, and having a Mohs hardness of 3 or less

[D] The method comprises the following steps And (3) a release agent.

The epoxy resin composition suitable for obtaining the fiber-reinforced molded article of the present invention has the following composition.

An epoxy resin composition containing an epoxy resin.

It comprises at least the following components [ A ], [ B ], [ C ] and [ D ].

And the component [ A ] is 60 to 100 parts by mass relative to 100 parts by mass of all the epoxy resins contained in the epoxy resin composition.

[A] The method comprises the following steps Aminophenol type epoxy resin

[B] The method comprises the following steps The following 2 acid anhydrides

[B1] The method comprises the following steps Acid anhydride having nadic anhydride structure

[B2] The method comprises the following steps Acid anhydride having hydride structure of phthalic anhydride

[C] The method comprises the following steps At least one filler selected from the group consisting of silicon compounds, magnesium compounds, calcium compounds, aluminum compounds, and inorganic carbon, and having a Mohs hardness of 3 or less.

[D] The method comprises the following steps And (3) a release agent.

According to a preferred embodiment of the present invention, the component [ B ] comprises 50 to 90 parts by mass of the component [ B1] and 50 to 10 parts by mass of the component [ B2], and the content of the component [ B ] is 50 to 200 parts by mass relative to 100 parts by mass of the component [ A ].

According to a preferred embodiment of the present invention, the component [ C ] is a particulate talc having an average particle diameter defined by a laser diffraction particle size distribution of 2 to 7 μm.

According to a preferred embodiment of the present invention, the component [ D ] is contained in an amount of 0.1 to 8 parts by mass per 100 parts by mass of the component [ A ].

According to a preferred embodiment of the present invention, an imidazole derivative is further blended as the component [ E ] in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the component [ A ].

The following manufacturing method is further disclosed in the present invention.

A method for producing a fiber-reinforced molded article, which comprises impregnating a reinforcing fiber bundle assembly comprising bundles of reinforcing fibers with a thermosetting resin composition, passing the resin-impregnated fiber base material through a draw molding zone, and simultaneously heating and curing the thermosetting resin composition to draw-mold the fiber-reinforced molded article into a predetermined shape,

a draw forming die having at least an inlet portion and an outlet portion and a post-curing furnace are disposed in the draw forming area,

performing the following steps in the drawing area: introducing the resin-impregnated fiber base material from an inlet of the draw-molding die, passing the resin-impregnated fiber base material through the die, and then, introducing the resin-impregnated fiber base material from an outlet of the die, and then, passing the resin-impregnated fiber base material through the post-curing furnace,

the draw forming region satisfies the following conditions (i) to (v).

(i) When the die temperature for the draw molding is Tp (c) and the in-die residence time obtained by dividing the passage length of the resin-impregnated fiber base material in the die (hereinafter referred to as die passage length) (m) by the molding speed (m/min) is h (min), the following equations (1) to (3) are satisfied.

230-100H is more than or equal to Tp is less than or equal to 252-80H formula (1)

Tp is more than or equal to 180 and less than or equal to 245 formula (2)

H is more than or equal to 0.1 and less than or equal to 0.9 formula (3)

(ii) The thermosetting resin composition is kept in a liquid state at an inlet of the drawing die.

(iii) The thermosetting resin composition is changed from a liquid state to a gelled state in the mold.

(iv) The thermosetting resin composition is kept in a gelled state at the outlet of the mold, wherein the degree of curing of the thermosetting resin composition is 33 to 80%.

(v) In the post-curing oven, the thermosetting resin composition is in a cured state with a degree of cure of 95% or more.

Here, the "passage length of the base material" is a distance through which the resin-impregnated fiber base material passes in the mold, and the "molding speed (m/min)" is a moving speed of the base material per 1 minute during molding.

According to a preferred embodiment of the present invention, in the drawing die, a region where the thermosetting matrix resin composition starts to be converted into a gelled state is located in a region having a length of 10 to 50% from an outlet portion of the passage with respect to a length of the die passage.

According to a preferred embodiment of the present invention, the resin-impregnated fiber base material is heated in the post-curing furnace without contacting the heating element.

ADVANTAGEOUS EFFECTS OF INVENTION

The epoxy resin composition having the features of the present invention can suppress the generation of fouling generated inside a die during drawing. Further, since the viscosity change during drawing is small, the drawing force can be maintained low for a long period of time, and the curability is excellent, high-speed and continuous drawing can be realized. The epoxy resin composition has a viscosity sufficient for impregnation and a cured product thereof has excellent heat resistance.

In the invention relating to the production method characterized by the relationship between the die temperature and the residence time in the die, by maintaining the thermosetting resin composition in a gelled state in the drawing die to have a degree of curing within a certain range, the occurrence of curing shrinkage occurring when the thermosetting matrix resin is cured from a liquid state to a solid state can be suppressed, the occurrence of so-called fouling adhering to and remaining on the inner surface of the drawing die can be suppressed, and continuous and high-speed drawing can be realized.

Drawings

Fig. 1 is a schematic view of a drawing forming machine for drawing forming a fiber-reinforced molded product of the present invention.

Fig. 2 is an enlarged sectional view of the drawing die section.

Fig. 3 is a sectional view showing a process from a gelled state to curing shrinkage of the thermosetting resin composition inside the drawing die.

FIG. 4 is a side sectional view showing that the gelation state of the thermosetting resin composition is controlled in the drawing according to the present invention.

Fig. 5 is a graph showing the relationship between the residence time in the mold and the mold temperature, which can obtain a poor curing region and a stain-generating region of the thermosetting resin composition in the draw molding according to the present invention.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings. The present invention is not limited to the drawings and the examples.

In the present invention, the "epoxy resin" refers to a compound having 2 or more epoxy groups in 1 molecule. In addition, a substance obtained by mixing materials necessary for the polymerization reaction to the curing reaction is referred to as an "epoxy resin composition", and a substance obtained by curing the compound through polymerization or crosslinking is referred to as an "epoxy resin cured product", a "cured product of an epoxy resin composition", or a "cured product".

The epoxy resin composition suitable for obtaining the fiber-reinforced molded article of the present invention has the following composition.

An epoxy resin composition containing an epoxy resin.

It comprises at least the following components [ A ], [ B ], [ C ] and [ D ].

And the component [ A ] is 60 to 100 parts by mass relative to 100 parts by mass of all the epoxy resins contained in the epoxy resin composition.

[A] The method comprises the following steps Aminophenol type epoxy resin

[B] The method comprises the following steps The following 2 acid anhydrides

[B1] The method comprises the following steps Acid anhydride having nadic anhydride structure

[B2] The method comprises the following steps Acid anhydride having hydride structure of phthalic anhydride

[C] The method comprises the following steps At least one filler selected from the group consisting of silicon compounds, magnesium compounds, calcium compounds, aluminum compounds and inorganic carbon, and having a Mohs hardness of 3 or less

[D] The method comprises the following steps And (3) a release agent.

By using 60 to 100 parts by mass, more preferably 80 to 100 parts by mass of the aminophenol type epoxy resin [ A ] in 100 parts by mass of all the epoxy resins contained in the epoxy resin composition of the present invention, the epoxy resin composition has a low viscosity and the heat resistance of the fiber-reinforced molded product is improved.

The aminophenol type epoxy resin is a resin having an epoxy group through an oxygen atom and a carbon atom directly bonded to a benzene ring, and having an epoxy group through a nitrogen atom and a carbon atom directly bonded to a benzene ring. The former generally has 1 epoxy group and the latter has 2 epoxy groups.

The aminophenol type epoxy resin preferably has a viscosity of 500 to 7,000 mPas at 25 ℃.

The viscosity here is determined by a measurement method using a cone-plate type rotational viscometer in ISO2884-1(1999) at 25 ℃.

If the viscosity at 25 ℃ of the aminophenol type epoxy resin is less than 500 mPas, the heat resistance of the resulting epoxy resin composition may be lowered. If the viscosity at 25 ℃ is more than 7,000 mPas, the viscosity of the resulting epoxy resin composition may become too high.

Examples of the aminophenol type epoxy resin having a viscosity of 500 to 7,000 mPas at 25 ℃ include "jER" (registered trademark) 630 (manufactured by Mitsubishi ケミカル), "アラルダイト" (registered trademark) MY0500 (manufactured by ハンツマン and アドバンスドマテリアル), and "アラルダイト" MY 0510. An example of the structure of the aminophenol type epoxy resin is shown below.

In addition, an acid anhydride is used as the curing agent. The acid anhydride includes 2 kinds of acid anhydrides [ B1] having a nadic acid anhydride structure and acid anhydrides [ B2] having a hydride structure of hydrogen phthalic anhydride.

The "nadic anhydride structure" in the component [ B1] includes nadic anhydride, that is, Bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic anhydride (Bicyclo [2.2.1] hep-5-ene-2, 3-dicarboxylic anhydride) itself, but is not limited thereto, and includes a structure in which atoms included in nadic anhydride are substituted with functional groups. Examples of the compound include compounds in which hydrogen bonded to carbon is substituted with a functional group, and one of preferable compounds is methylnadic anhydride. Further, as long as it can function as the curing agent of the component [ a ], a compound having a structure in which hydrogen bonded to an atom contained in nadic anhydride is partially substituted with a functional group is also suitable.

Specific examples thereof include nadic anhydride and methylnadic anhydride, and the component [ B1] is particularly preferably methylnadic anhydride.

The acid anhydride having a hydrogenated structure of phthalic anhydride as the component [ B2] is a substance having a chemical structure of hydrogenated product of phthalic anhydride. The hydride containing phthalic anhydride itself is not limited to this, and includes a structure in which atoms included in the hydride containing phthalic anhydride are substituted with functional groups. Examples of the compound include compounds in which hydrogen bonded to carbon is substituted with a functional group, and preferable examples of the compound include tetrahydromethylphthalic anhydride and hexahydromethylphthalic anhydride. Further, as long as it can function as the curing agent of the component [ a ], a compound having a structure in which atoms included in nadic anhydride are partially substituted with functional groups is also suitable.

Specific examples of such a component [ B2] include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and trialkyltetrahydrophthalic anhydride. The component [ B2] is particularly preferably tetrahydromethylphthalic anhydride or hexahydromethylphthalic anhydride. The content ratio of the component [ B1] and the component [ B2] is preferably 50 to 90 parts by mass of the component [ B1] and 50 to 10 parts by mass of the component [ B2] in 100 parts by mass of the acid anhydride [ B ] (i.e., [ B1] and [ B2 ]).

Preferably, the component [ B1] is 55 to 85 parts by mass and the component [ B2] is 45 to 15 parts by mass. More preferably, the component [ B1] is 60 to 80 parts by mass and the component [ B2] is 40 to 20 parts by mass. More preferably, the component [ B1] is 70 to 75 parts by mass and the component [ B2] is 30 to 25 parts by mass.

By including 50 to 90 parts by mass of the component [ B1] in 100 parts by mass of the acid anhydride [ B ], a cured product obtained from the epoxy resin composition can have high heat resistance. When the content of the component [ B1] is less than 50 parts by mass, the heat resistance of the fiber-reinforced molded article may be lowered.

By including 50 to 10 parts by mass of the component [ B2] in 100 parts by mass of the acid anhydride [ B ], the initial viscosity of the epoxy resin composition can be suppressed low and the curing rate can be improved. When the content of the component [ B2] is less than 10 parts by mass, a resin composition having poor initial low viscosity may be obtained.

The viscosity of the component [ B2] at 25 ℃ is preferably 20 mPas to 1,000 mPas. The viscosity here is determined by a measurement method using a cone-plate type rotational viscometer in ISO2884-1(1999) at 25 ℃.

Examples of commercially available methylnadic anhydride include "カヤハード" (registered trademark) MCD (viscosity: 250 mPas, manufactured by Nippon Kagaku K.K.) and "ARADUR" (registered trademark) HY906 (viscosity: 200 mPas, manufactured by ハンツマン and アドバンスドマテリアル). Examples of commercially available products of tetrahydromethylphthalic anhydride include HN-2000 (viscosity: 40 mPas, manufactured by Hitachi chemical Co., Ltd.), HN-2200 (viscosity: 65 mPas, manufactured by Hitachi chemical Co., Ltd.), and "ARADUR" (registered trademark) HY917 (viscosity: 75 mPas, manufactured by ハンツマン & アドバンスドマテリアル). Examples of commercially available products of hexahydromethylphthalic anhydride include HN-5500 (viscosity: 65 mPas, manufactured by Hitachi chemical Co., Ltd.).

The amount of the acid anhydride blended is preferably in the range of 0.5 to 1.5 equivalents of acid anhydride equivalent (value obtained by dividing the molecular weight of the acid anhydride by the number of acid anhydride groups) to 1 equivalent of epoxy group contained in the total epoxy resin including the component [ a ]. More preferably 0.7 to 1.2 equivalents. Although 2 preferred ranges are shown, a combination of the preferred upper and lower values can be used. If the amount is less than 0.5 equivalent, the initial viscosity of the resin composition may become high and curing may become insufficient, and if it exceeds 1.5 equivalents, the mechanical properties of the cured product may be deteriorated.

The content of the component [ B ] is preferably 50 to 200 parts by mass per 100 parts by mass of the component [ A ], and if the component [ B ] is less than 50 parts by mass, the initial viscosity of the resin composition may become high and curing may become insufficient, and if it exceeds 200 parts by mass, the mechanical properties of the cured product may be deteriorated.

In addition, in the epoxy resin composition of the present invention, as the component [ C ], each of the fillers having a mohs hardness of 3 or more and at least one selected from the group consisting of a silicon compound, a magnesium compound, a calcium compound, an aluminum compound and an inorganic carbon is contained as a component.

As the inorganic carbon, a simple substance such as graphite, CaC, or the like can be used₂SiC, and the like are carbides called carbides. On the other hand, as for silicon, magnesium, calcium and aluminum, substances existing in the form of simple substances including them also include compounds containing these atoms. Since the filler enters between the carbon fibers of the fiber base material, an effect of suppressing curing shrinkage can be obtained when the resin composition is cured. Further, if the mohs hardness is 3 or less, the material is soft, and thus the mold can be less damaged. Examples thereof include calcium carbonate, aluminum hydroxide, talc, and carbon black. Among them, talc (hydrous magnesium silicate (Mg)₃Si₄O₁₀(OH)₄) In particular particulate talc.

Further, since the particulate talc having an average particle diameter of 2 to 7 μm as measured by a laser diffraction particle size distribution meter is a small particle diameter particle, the talc is easily taken into the space between the carbon fibers, and the effect of reducing shrinkage is further enhanced. The average particle diameter is preferably 3 to 6 μm, more preferably 3.5 to 5.5 μm. The upper limit and the lower limit may be combined.

The amount of the filler [ C ] contained in the epoxy resin of the present invention is preferably 0.5 to 5 parts by mass per 100 parts by mass of the aminophenol epoxy resin [ A ].

The release agent [ D ] is preferably an ester of a polyhydric alcohol such as glycerol or pentaerythritol and a fatty acid. The number of carbon atoms of the fatty acid is preferably 12 or more. Further, it is preferably 30 or less. Preferably, for example, oleate or stearate. Pentaerythritol tetraoleate or glyceryl isostearate may be more preferably used.

By using a mold release agent which is liquid at 25 ℃, it is possible to uniformly mix the epoxy resin composition in a liquid state. By mixing a release agent in the resin in advance, the releasability between the thermosetting resin composition and the drawing die 6 can be improved, and the drawing formability can be improved.

The amount of the release agent is preferably 0.1 to 8 parts by mass per 100 parts by mass of the aminophenol epoxy resin [ A ]. More preferably 0.2 to 6 parts by mass. The range may be a combination of any of the above upper and lower limits. If the amount is less than 0.1 part by mass, sufficient releasability may not be obtained. Further, if the amount is more than 8 parts by mass, the strength of the molded article itself may be lowered, or the adhesion between the molded article and the coating film may be lowered.

As such a release agent, in order to suppress the influence on the viscosity of the resin composition, it is preferable to use a release agent in a liquid state at 25 ℃ having a viscosity of 50mPa · s or more and 1,000mPa · s or less.

Further, in order to effect curing of the epoxy resin, it is preferable to contain a curing catalyst [ E ]. The curing catalyst is not particularly limited as long as it promotes the chemical reaction between the epoxy resin and the acid anhydride curing agent, and is preferably an imidazole derivative from the viewpoint of the balance between viscosity stability and heat resistance.

The imidazole derivative refers to a compound having an imidazole ring in the molecule. Specific examples thereof include imidazole, 1-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1, 2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-isobutyl-2-methylimidazole and 1-aminoethyl-2-methylimidazole, but are not limited thereto.

Among imidazole derivatives, imidazole derivatives having a substituent at the 1-position of the five-membered ring are excellent in stability of viscosity, and are preferably used. Among them, in order to prevent the viscosity of the epoxy resin composition from being excessively increased, it is preferable to use an imidazole derivative having a melting point of 50 ℃ or lower, more preferably 25 ℃ or lower, and being in a liquid state at 25 ℃. These imidazole derivatives may be used alone or in combination of two or more. Commercially available imidazole derivatives having a substituent at the 1-position include 1,2DMZ (1, 2-dimethylimidazole, manufactured by seikagaku corporation), 1B2MZ (1-benzyl-2-methylimidazole, manufactured by seikagaku corporation), 1B2PZ (1-benzyl-2-phenylimidazole, manufactured by seikagaku corporation), and DY070 (1-methylimidazole, manufactured by ハンツマン and アドバンスドマテリアル).

The imidazole derivative is preferably contained in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the aminophenol type epoxy resin [ A ]. If the amount is less than 0.1 part by mass, the curing rate of the thermosetting resin composition may be low and the rapid curing property may be poor. Further, if it is more than 5 parts by mass, the viscosity stability of the resin composition is sometimes deteriorated and it is not suitable for continuous production.

As the reinforcing fibers constituting the reinforcing fiber bundle, glass fibers, aramid fibers, polyethylene fibers, silicon carbide fibers, and carbon fibers are preferably used. In particular, carbon fiber is preferably used in order to obtain a molded article which is lightweight, has high performance, and has excellent mechanical properties.

Carbon fibers are classified into polyacrylonitrile-based carbon fibers, rayon-based carbon fibers, pitch-based carbon fibers, and the like. Among them, polyacrylonitrile-based carbon fibers having high tensile strength are preferably used. The polyacrylonitrile-based carbon fiber can be produced, for example, through the following steps. A spinning dope containing polyacrylonitrile obtained from a monomer containing acrylonitrile as a main component is spun by a wet spinning method, a dry spinning method or a melt spinning method. The coagulated yarn obtained by spinning is converted into a precursor through a yarn-making step, and then converted into carbon fiber through a flame-resistant step, a carbonization step, and the like.

As the form of the carbon fiber, twisted yarn, untwisted yarn, or the like can be used. In the case of twisted yarn, the filaments constituting the reinforcing fiber bundle are not aligned, and thus the mechanical properties of the fiber-reinforced composite material tend to be degraded. Therefore, it is preferable to use untwisted or non-twisted yarns having an excellent balance between moldability and strength characteristics of the fiber-reinforced composite material.

When carbon fibers are used as the reinforcing fibers, the carbon fiber bundle is composed of 2,000 to 70,000 filaments, the fineness of each filament is preferably in the range of 50 to 5000tex, more preferably 10,000 to 60,000 filaments, and the fineness of each filament is 100 to 2000 tex. The range may be a combination of any of the above upper and lower limits. Here, the fineness (tex) is the mass per 1000m of filament (g/1000 m). Impregnation of an epoxy resin composition into carbon fibers having a filament number of 2000 to 70000 and a filament fineness of 50 to 5000tex by an epoxy resin composition has been difficult in the prior art, but the epoxy resin composition of the present invention can be easily impregnated between single fibers because of its low viscosity.

The tensile modulus of elasticity of such carbon fibers is preferably in the range of 180 to 400 GPa. If the tensile elastic modulus is in this range, the resulting fiber-reinforced composite material can be made rigid, and therefore the resulting molded article can be made lightweight. In general, the higher the elastic modulus of the carbon fiber, the lower the strength tends to be, but if the elastic modulus is in this range, the strength of the carbon fiber itself can be maintained. The elastic modulus is more preferably in the range of 200 to 370GPa, and still more preferably in the range of 220 to 350 GPa. The range may be a combination of any of the above upper and lower limits. Here, the tensile modulus of carbon fibers is a value measured in accordance with JIS R7601-2006.

As commercially available products of carbon fibers, the following can be mentioned.

"トレカ (registered trademark)" T300-12000 (tensile strength: 3.5GPa, tensile modulus of elasticity: 230GPa), "トレカ (registered trademark)" T300B-12000 (tensile strength: 3.5GPa, tensile modulus of elasticity: 230GPa), "トレカ (registered trademark)" T400HB-6000 (tensile strength: 4.4GPa, tensile modulus of elasticity: 250GPa), "トレカ (registered trademark)" T700SC-12000 (tensile strength: 4.9GPa, tensile modulus of elasticity: 230GPa), "トレカ (registered trademark)" T800-12000 (tensile strength: 5.5GPa, tensile modulus of elasticity: 294), "トレカ (registered trademark)" T800SC-24000 (tensile strength: 5.9GPa, tensile modulus of elasticity: 294GPa), "53925 (registered trademark)" T830 3-6000 (tensile strength: 5.3GPa, ", tensile modulus of elasticity: 294, and" 53942 "(tensile modulus of 84-1206 GPa)," 465.84 GPa "," (tensile strength: 1206), tensile modulus of elasticity: 294GPa), "トレカ (registered trademark)" T1100GC-12000 (tensile strength: 7.0GPa, tensile modulus of elasticity: 324GPa), "トレカ (registered trademark)" M35JB-12000 (tensile strength: 4.7GPa, tensile modulus of elasticity: 343GPa), "トレカ (registered trademark)" M40JB-12000 (tensile strength: 4.4GPa, tensile modulus of elasticity: 377GPa) "トレカ (registered trademark)" M30SC-18000 (tensile strength: 5.5GPa, tensile modulus of elasticity: 294GPa) (manufactured by imperial レ, ltd.). PX35 (tensile strength: 4.1GPa, tensile modulus of elasticity: 242GPa), manufactured by Zoltek corporation).

Next, an invention of a preferable production method of the drawn fiber-reinforced molded product will be described. Refer to fig. 4. A thermosetting resin composition represented by an epoxy resin composition is impregnated into a bundled fiber base material, and the obtained resin-impregnated fiber base material 7 is passed through a distance from the draw molding zone 17. The thermosetting resin composition is heated and cured during the passage, and is then drawn and molded into a predetermined shape. In a preferred manufacturing method of the present invention, as shown in fig. 4, at least the drawing die 6 and the post-curing oven 24 are disposed in the drawing area 17. The resin-impregnated fiber base material 7 is introduced from an inlet 11 of the drawing die 6, passes through the inside of the drawing die 6, and is led out from an outlet 12 of the drawing die 6. Then, the resin-impregnated fiber base material 7 passes through the post-curing oven 24. At the entrance 11 of the die, the thermosetting resin composition remains in a liquid state, but inside the drawing die 6, the thermosetting resin composition turns into a gelled state. Preferably, the thermosetting resin composition is in a gelled state with a curing degree of 33 to 80% at the outlet portion 12 of the mold, and is in a cured state with a curing degree of 95% or more in the post-curing oven 24.

Fig. 1 shows a general drawing process. In the draw forming step 1, the reinforcing fiber bundle 2 is drawn out from the creel 3 while being pulled by the drawer 10. The reinforcing fiber bundle 2 is introduced into the resin bath 4 through a guide roller (not shown) to adhere the thermosetting resin composition. Further, the excess thermosetting resin composition is removed by rubbing with the squeeze bar 5. The reinforcing fibers are further positioned one by the guide 30 so as to be well-balanced to enter the drawing die 6 having a desired cross-sectional shape. The resin that cannot pass through the die together with the reinforcing fibers and eventually becomes an excess flows back from the die and drops from the entrance of the die 6 to be removed.

The resin-impregnated fiber base material 7 impregnated with the thermosetting resin composition is heated while passing through the draw-forming die 6, and the thermosetting resin composition is cured. After being discharged from the outlet of the drawing die, the product is wound by a winder 8. In a preferred method of manufacture in the present invention, the post-cure oven 24 is passed through before being wound.

Next, a description will be given of a state in which a wire is broken due to an increase in drawing force in a conventional drawing manufacturing process, with reference to an enlarged side sectional view of a drawing die portion of fig. 2. The resin-impregnated fiber base material 7 is introduced from an inlet 11 of the drawing die 6 and is conveyed at a constant drawing speed in the drawing die 6 heated to a constant temperature. The thermosetting resin composition contained in the resin-impregnated fiber base material 7 introduced from the mold inlet 11 is temporarily maintained in a liquid state in the liquid region 14. Then, by heating from the drawing die 6, a part of the thermosetting resin composition starts to gel, and the gelled state region 15 is immediately followed. Then, the thermosetting resin composition of the resin-impregnated fiber base material 7 is cured to be in a solid state and discharged from the outlet portion 12 of the mold.

This state is shown in detail in a cross-sectional view perpendicular to the traveling direction of the resin-impregnated fiber base material 7 in fig. 3. FIG. 3[ a ] shows a cross-sectional view A-A' of FIG. 2. Fig. 3[ a ] shows the presence of the thermosetting resin composition 20 in a gelled state contained in the resin-impregnated fiber base material 7 at the initial stage in the gelled region 15. FIG. 3B shows a cross-sectional view B-B' of FIG. 2. In fig. 3 b, the latter half of the gelled region 15 shown in fig. 2 is shown in a state in which the thermosetting resin composition is in a cured state 21 on the surface layer of the resin-impregnated fiber base material 7. Further, FIG. 3[ C ] shows a cross-sectional view C-C' of FIG. 2. At the stage of the solid region 16, the thermosetting resin composition is cured until the resin impregnates the inside of the fiber base material 7, and the cured state 22 is obtained. During the curing shrinkage, a part of the resin component adheres to and remains on the inner surface of the drawing die, so that a resin residue 13 called "dirt" is generated, and the drawing force increases during the production process, thereby causing breakage of the reinforcing fibers.

In contrast, in the method of manufacturing a fiber-reinforced molded product of the present invention, as shown in fig. 4, the draw die 6 and the post-curing oven 24 are disposed in the draw region 17. The resin-impregnated fiber base material 7 is introduced from the inlet 11 of the drawing die 6, passed through the inside of the drawing die 6, and led out from the outlet 12 of the drawing die 6 without accumulation of dirt, and then passed through the post-curing furnace 24. The position where no dirt is accumulated is denoted by reference numeral 23.

First, the resin-impregnated fiber base material 7 is introduced from the die inlet 11. The thermosetting resin composition is kept in a liquid state in the liquid region 14 inside the drawing die 6. Then, inside the drawing die 6, the thermosetting resin composition is changed from the gelled state 15 to the cured solid state. The curing degree of the thermosetting resin composition at the die outlet portion 12 is suppressed so that the curing degree of the thermosetting resin composition is 33 to 80%. This can suppress the generation of resin residue 13 called "dirt" which is attached to the inner surface of the drawing die 6. Such adjustment of the degree of curing can be performed by adjusting the temperature of the mold, the length of the mold, and the molding speed, for example. This can prevent the thermosetting resin composition from being cured and shrunk inside the drawing die 6, and as a result, the generation of resin residues 13 called dirt on the inner surface of the drawing die 6 can be suppressed. Further, the resin-impregnated fiber base material 7 discharged from the die outlet portion 12 is introduced into a post-curing furnace 24, and heated in the furnace 24, whereby the thermosetting resin composition is cured to a degree of cure of 95% or more, and a drawn molded product can be produced.

In the outlet portion 12 of the mold, if the degree of cure of the thermosetting resin composition is less than 33%, curing failure may occur. Further, if the degree of cure of the thermosetting resin composition exceeds 80% in the die outlet portion 12, it may be difficult to suppress the generation of resin residues 13 called fouling in the inside of the drawing die 6.

The curing degree of the thermosetting resin composition at the outlet portion 12 of the mold is preferably 33 to 80%, more preferably 50 to 79%, even more preferably 60 to 79%, and particularly preferably 76 to 77%. The range may be a combination of any of the above upper and lower limits.

Here, the degree of curing can be determined as follows: in the molding stage, a molded article taken out from each of the mold and the post-curing oven was sampled in an appropriate amount, the residual heat was obtained from the heat release peak obtained by DSC measurement (differential scanning calorimetry), and the ratio of the heat release to the heat release of the resin composition obtained from the heat release peak obtained by DSC measurement of the uncured resin composition in advance was obtained by the following formula.

Degree of cure of 100- (exothermic amount of molded article)/(exothermic amount of resin composition x mass fraction of thermosetting resin of molded article)

In the present invention, the viscosity of the thermosetting resin composition at the inlet 11 of the drawing die is preferably 3000mPa · s or less. This allows the fiber base material 2 to be impregnated with the thermosetting resin composition continuously and satisfactorily, and also allows the fiber base material 7 impregnated with the resin to be maintained in a liquid state satisfactorily inside the drawing die 6. Preferably 2000 mPas or less, more preferably 1000 mPas or less.

In the present invention, it is preferable that the following relationship is satisfied when Tp (deg.c) is the temperature of the drawing die 6 and h (min) is the in-die residence time obtained by dividing the length (m) of the passage length of the resin-impregnated fiber base material (hereinafter referred to as the die passage length) in the drawing die 6 by the molding speed (m/min).

230-100H≤Tp≤252-80H

180≤Tp≤245

0.1≤H≤0.9。

Here, the temperature Tp of the die is a temperature of a passage of the resin-impregnated fiber base material in the drawing die. It is preferable to insert a thermocouple during the drawing for measurement. However, since it is difficult to measure the temperature while molding in this method, it is preferable to measure the temperature in the vicinity of the fiber base material passage by inserting a thermocouple from the outside into a measurement hole opened in the side surface of the mold as another method. In this case, it is preferable to provide a plurality of measurement points, and in this case, the mold temperature Tp is an average value of these measurement points. The difference between the temperature at each measurement point and Tp is preferably within. + -. 25 ℃.

The relationship of the above formula represents a range of conditions suitable for maintaining the thermosetting resin composition in a gelled state with a degree of curing of 33 to 80% in the die outlet portion 12.

Fig. 5 shows the relationship between the residence time in the die and the die temperature in the drawing according to the present invention. The vertical axis represents the mold temperature Tp (. degree. C.) and the horizontal axis represents the residence time in the mold H (min). Further, in fig. 5, a region 25 of the thermosetting resin composition indicates a region in which curing failure is likely to occur, a region 26 indicates an appropriate region, and a region 27 indicates a region in which fouling is likely to occur.

The characteristic line 28 indicates a relationship of Tp 230-.

The characteristic line 29 indicates the relationship Tp of 252 to 80H, and the region 26 located on the left side thereof is a region in which the degree of cure of the thermosetting resin composition can be maintained at 80% or less at the die outlet portion 12.

In addition, the heating temperature Tp of the drawing die 6 is 180 to 245 ℃. If the heating temperature Tp of the drawing die 6 is less than 180 ℃, curing failure may occur. Although the curing failure can be avoided by reducing the speed, reducing the drawing speed leads to an increase in the production cost.

Further, if the heating temperature Tp of the drawing die 6 exceeds 245 ℃, fouling is likely to occur in some cases. Therefore, although the generation of fouling can be suppressed by increasing the speed, the tension of the wire may become too strong and the wire may be broken.

The residence time H in the mold is preferably 0.1 to 0.9min, and if the residence time H in the mold is less than 0.1min, poor curing may occur. If the in-mold residence time H exceeds 0.9min, fouling is sometimes liable to occur.

The molding speed is preferably 0.18 to 16 m/min. Preferably 0.6 to 10m/min, more preferably 1 to 8m/min, and further preferably 1.2 to 6 m/min. The range may be a combination of any of the above upper and lower limits.

In the present invention, it is preferable that the glass transition point of the thermosetting resin composition after heat curing is Tg (c), and the heating temperature Tp (c) of the drawing die 6 satisfy the following relationship.

Tg-40℃≤Tp≤Tg+25℃。

By setting the heating temperature Tp to Tg-40 ℃ or higher, the heat resistance of the drawn fiber-reinforced molded article can be sufficiently ensured. By setting the heating temperature Tp to "Tg +25 ℃ or lower", it is possible to prevent the molded article from being deformed by heat or the thermosetting resin composition from being decomposed.

The glass transition temperature is a middle point temperature (Tm) determined by a DSC method in accordance with JIS K7121 (1987). An example of the measuring apparatus is a differential scanning calorimeter DSC Q2000 (manufactured by ティー, エイ, インスツルメント), and in this case, the measurement is performed in a Modulated mode. The DSC measurement was carried out at a temperature increase rate of 5 ℃ per minute under a nitrogen atmosphere.

In the present invention, it is preferable that the temperature in the post-curing furnace is Tc (c), and the glass transition point Tg (c) of the thermosetting resin composition after heat curing satisfies the following equation.

Tg≤Tc≤Tg+73℃。

By setting the temperature Tc in the post-curing furnace to be not less than Tg, the heat resistance of the obtained fiber-reinforced molded article can be sufficiently ensured. By setting the heating temperature Tc to Tg +73 ℃ or lower, it is possible to prevent the molded article from being deformed by heat or the thermosetting resin composition from being decomposed.

Refer to fig. 4. In the present invention, it is preferable that the region in which the thermosetting resin composition is converted into a gelled state in the inside of the drawing die 6 is within a range of a length from the outlet portion of the drawing die to 10 to 50% of the total length of the passage of the resin-impregnated fiber base material in the drawing die. This reduces the degree of curing of the thermosetting resin composition in the vicinity of the outlet portion 12 of the mold, and the curing shrinkage region can be moved in the direction of the outlet portion 12 of the mold, thereby shortening the curing shrinkage region. The occurrence of curing shrinkage of the thermosetting resin composition inside the drawing die 6 can be avoided, and as a result, the generation of resin residues 13 called dirt on the inner surface of the drawing die 6 can be suppressed. The length of the region is preferably in the range of 15 to 45%, more preferably 20 to 40%. The preferable upper limit value and the preferable lower limit value in the above-described preferable two ranges may be combined.

In the present invention, it is preferable that the resin-impregnated fiber substrate 7 is heated without contacting the heating element in the post-curing furnace 24. The post-curing is performed to completely cure the resin of the resin-impregnated fiber substrate 7 that has passed through and discharged from the draw die 6, and if the resin is not in contact with the heating element, residual dirt does not adhere to the inside of the post-curing furnace even if curing shrinkage occurs in the furnace.

The present invention can be applied to molding of fiber-reinforced molded articles of various shapes if the cross-sectional shape is the same. Examples thereof include a cylindrical rod-shaped molded article, a rod-shaped molded article having a polygonal cross section, a sheet-shaped thin article molded article, and a thick article molded article having a rectangular cross section, and they may be hollow. Further, although not particularly limited, if the thickness of the molded article (the thickness from the outermost surface to the hollow portion in the case of a hollow article) is 20mm or less, rapid solidification shrinkage due to heat accumulation inside the molded article is suppressed, and dimensional stability is often good from the viewpoint of dimensional stability.