TWI762891B - Matrix resin for fiber-reinforced resin, matrix resin film for fiber-reinforced resin, composite body, prepreg, carbon fiber-reinforced resin molded body, and manufacturing method of carbon fiber-reinforced resin molded body - Google Patents

Abstract

The present invention provides a matrix resin for fiber-reinforced resin, which is composed of a resin composition containing a main agent and a cross-linking agent, wherein the main agent is a maleic acid-modified polyolefin graft-modified with maleic anhydride. The crosslinking agent is composed of epoxy group-containing resin, and the graft modification rate of the maleic acid-modified polyolefin obtained from the maleic anhydride is 0.5 mass % or more and 3.0 mass % Hereinafter, the solid content concentration of the main agent is 80% by mass or more and 99.5 mass% or less relative to the total amount of the matrix resin for fiber-reinforced resin, and the solid content concentration of the crosslinking agent is relative to the total amount of the matrix resin for fiber-reinforced resin. It is 0.5 mass % or more and 20 mass % or less.

Description

Matrix resin for fiber-reinforced resin, matrix resin film for fiber-reinforced resin, composite body, prepreg, carbon fiber-reinforced resin molded body, and manufacturing method of carbon fiber-reinforced resin molded body

The present invention relates to a matrix resin for fiber-reinforced resin, a matrix resin film for fiber-reinforced resin, a composite, a prepreg, a carbon fiber-reinforced resin molded body, and a method for producing the carbon fiber-reinforced resin molded body. This application claims priority based on Japanese Patent Application No. 2019-057348 for which it applied on March 25, 2019, and the content of this application is incorporated herein by reference.

A fiber-reinforced resin in which a fiber material such as carbon fiber is impregnated with a matrix resin can provide a material with high strength and significantly reduced weight. Therefore, fiber-reinforced resins are attracting attention in a wide range of fields such as automobile parts and aircraft parts. From the viewpoint of improving the weight reduction and strength, carbon fibers can be used as the fiber material. However, the interface adhesion between the carbon fiber and the matrix resin is poor, and there is a problem that the carbon fiber cannot be sufficiently reinforced.

For example, Patent Document 1 describes a carbon fiber-reinforced resin composition, which specifically specifies the fiber length or blending ratio of carbon fibers in order to improve the interface adhesion between polyolefin resin and carbon fiber, and to improve the strength and impact resistance of the resulting molded product. . [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-154795.

[The problem to be solved by the invention]

The fiber-reinforced resin molding system is produced by molding a prepreg obtained by impregnating a fiber material with a matrix resin. In the impregnation step, voids (also referred to as voids) generated at the interface between the matrix resin and the fiber material may cause a decrease in the strength of the molded product. Furthermore, when producing a fiber-reinforced resin molded body, a matrix resin that hardens in a short time is required.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a matrix resin for fiber-reinforced resin, a matrix resin film for fiber-reinforced resin, a composite, a prepreg, and a carbon fiber-reinforced resin that can be easily impregnated into a fiber material and can be hardened in a short time. A molded body, and a method for producing a carbon fiber reinforced resin molded body. [means to solve the problem]

That is, the present invention adopts the following constitutions. [1] A matrix resin for fiber-reinforced resin, comprising a resin composition containing a main agent and a crosslinking agent, wherein the main agent is a maleic acid-modified polyolefin graft-modified with maleic anhydride The crosslinking agent is composed of epoxy group-containing resin, and the graft modification rate of the maleic acid-modified polyolefin obtained from the maleic anhydride is 0.5 mass % or more and 3.0 mass % or less, The solid content of the main agent is 80% by mass to 99.5% by mass relative to the total amount of the matrix resin for fiber-reinforced resin, and the solid content of the cross-linking agent is 0.5 relative to the total amount of the matrix resin for fiber-reinforced resin. mass % or more and 20 mass % or less. [2] The matrix resin for fiber-reinforced resin according to [1], wherein the maleic acid-modified polyolefin has a melt viscosity of 1000 mPa·s or more and 50000 mPa·s or less at 180°C. [3] The matrix resin for a fiber-reinforced resin according to [1] or [2], wherein the graft modification rate is 0.5 mass % or more and 2.5 mass % or less. [4] The matrix resin for fiber-reinforced resin according to any one of [1] to [3], wherein the epoxy group-containing resin has a weight average molecular weight of 300 or more and 50,000 or less. [5] The matrix resin for fiber-reinforced resin according to any one of [1] to [4], wherein the epoxy group-containing resin is selected from the group consisting of novolac type, phenol type, bisphenol A type, bisphenol type One or more of the group consisting of F type. [6] A matrix resin film for fiber-reinforced resin, comprising the matrix resin for fiber-reinforced resin according to any one of [1] to [5], and having a film thickness of 10 μm or more and 200 μm or less. [7] The matrix resin film for a fiber-reinforced resin according to [6], wherein the dynamic storage viscoelasticity coefficient (E') measured by dynamic viscoelasticity at 150° C. is 1.0×10 ⁴ Pa or more and 1.0×10 Below ⁶ Pa. [8] A composite comprising the matrix resin film for fiber-reinforced resin according to [6] or [7], and a fiber material. [9] The composite according to [8], wherein the fiber material is carbon fiber, aramid fiber, or glass fiber. [10] A prepreg comprising the matrix resin film for fiber-reinforced resin according to [6] or [7], and carbon fibers. [11] The prepreg according to [10], wherein the carbon fibers are continuous fibers. [12] A carbon fiber-reinforced resin molded body obtained by laminating the prepreg described in [10] or [11]. [13] A method for producing a carbon fiber reinforced resin molded body, comprising the steps of producing a carbon fiber reinforced resin molded body obtained by laminating the prepregs according to [10] or [11], comprising the steps of: A step of laminating to obtain a layered body; and a step of stamping the obtained layered body. [Inventive effect]

According to the present invention, it is possible to provide a matrix resin for a fiber-reinforced resin, a matrix resin film for a fiber-reinforced resin, a composite, a prepreg, a carbon fiber-reinforced resin, and a carbon fiber-reinforced resin that can be easily impregnated into a fiber material and can be hardened in a short time. Manufacturing method.

Hereinafter, the present invention will be described based on preferred embodiments.

[Matrix resin for fiber reinforced resin] The matrix resin for fiber-reinforced resin of the present embodiment consists of a resin composition containing a main ingredient and a crosslinking agent. The main agent is composed of maleic acid-modified polyolefin, and the maleic acid-modified polyolefin is maleic acid anhydride or maleic acid with a graft modification rate of 0.5 mass % or more and 3.0 mass % or less. Acid-modified polyolefins. The crosslinking agent is composed of epoxy group-containing resin. The epoxy group-containing resin functions as a crosslinking agent for crosslinking the maleic acid-modified polyolefin.

In this specification, polymers obtained by graft-modifying an unmodified polyolefin resin with either or both of maleic anhydride and maleic acid are collectively referred to as "maleic acid-modified polyolefins".

Hereinafter, the term "unmodified polyolefin resin" refers to a polyolefin resin not graft-modified with maleic anhydride or maleic acid.

In maleic acid-modified polyolefin, the ratio of graft-modified unmodified polyolefin resin by maleic anhydride and the ratio of graft-modified unmodified polyolefin resin by maleic acid The ratio is collectively referred to as "graft modification ratio of maleic acid-modified polyolefin obtained from maleic acid".

[Main agent: maleic acid modified polyolefin] The main agent used in this embodiment has thermoplasticity. As described above, the maleic acid-modified polyolefin used as the main agent of the present embodiment is graft-modified by using either or both of maleic anhydride and maleic acid to the unmodified polyolefin resin. and obtained.

As a production method of maleic acid-modified polyolefin, the following two methods can be mentioned. (1) A method of graft-modifying an unmodified polyolefin resin with at least one or both of maleic anhydride and maleic acid by melt-kneading. (2) A method of copolymerizing an olefin monomer and an acid functional group-containing monomer. As the "acid functional group-containing monomer", either or both of maleic anhydride and maleic acid are used.

The graft modification is preferably carried out in the presence of a radical polymerization initiator such as an organic peroxide or an aliphatic azo compound.

In the constitution of maleic acid-modified polyolefin, as the olefin monomer in the case of copolymerization with maleic anhydride or maleic acid, or the olefin monomer constituting the unmodified polyolefin resin, ethylene, propylene, 1 -One or more of butene, isobutene, 1-hexene, 1-octene, α-olefin, etc.

Examples of unmodified polyolefin resins include polyethylene, polypropylene, poly-1-butene, polyisobutylene, copolymers of ethylene and propylene, copolymers of propylene and 1-butene, propylene and ethylene, or α- One or more of random copolymers of olefins, block copolymers of propylene and ethylene or α-olefin, etc. Among them, polypropylene-based resins such as homopolypropylene as a propylene homopolymer, a propylene-ethylene block copolymer, a propylene-ethylene random copolymer, and a propylene-1-butene copolymer are preferable. That is, in this embodiment, as maleic acid-modified polyolefin, maleic acid-modified polypropylene resin is preferable.

When the monomer constituting the maleic acid-modified polyolefin contains 1-butene, the molecular motion when the matrix resin for fiber-reinforced resin is heated is promoted. In the case where the main agent and the cross-linking agent have functional groups that can react with each other, the chance of contact between the functional groups of the main agent and the cross-linking agent increases, the durability of the matrix resin for fiber-reinforced resin, the resistance to the adherend. Adhesion is further improved.

In the case where the maleic acid-modified polyolefin contains unreacted maleic acid or maleic anhydride, there is a possibility that the adhesive force will decrease. Therefore, maleic acid-modified polyolefin containing no unreacted maleic acid or maleic anhydride is preferable as the main agent of the matrix resin for fiber-reinforced resin. In this embodiment, maleic acid-modified polyolefin obtained by removing unreacted maleic acid or maleic anhydride from the products obtained by the above-mentioned (1) and (2) production methods is preferably used. main agent.

·Graft modification rate The graft modification rate of the maleic acid-modified polyolefin obtained from maleic anhydride or maleic acid is 0.5 mass % or more and 3.0 mass % or less, preferably 0.5 mass % or more and 2.5 mass % or less. The "graft modification rate" refers to a value obtained by measurement by the following method.

[Measuring method 1] A film having a thickness of about 100 μm was produced by hot pressing a particulate sample of maleic anhydride, an absorption peak appeared at 1780 cm ⁻¹ in the infrared absorption spectrum, and a calibration curve obtained separately The content rate (mass %) of maleic acid was measured, and the obtained value was used as the content rate (mass %) of the total maleic anhydride. Let the obtained value be A.

After dissolving the granular measurement sample in boiled xylene, the measurement sample was reprecipitated in methanol from the obtained solution. Then, the precipitate was vacuum-dried at 80° C. for 6 hours to obtain a powdery sample.

The content ratio of maleic anhydride contained in the obtained sample was measured by the same method as above, and the obtained value was used as the content ratio (mass %) of maleic anhydride grafted to polyolefin in the sample. Let the obtained value be B.

Divide the content ratio (B) of the graft-modified maleic anhydride by the content ratio (A) of the total maleic anhydride, and express the obtained value as a percentage, and express the value expressed as a percentage ((B/A)× 100) as the graft modification rate (mass %) of maleic anhydride in the measurement sample.

In addition, the graft modification rate can also be measured by the following method.

[Measurement method 2] After dissolving the measurement sample of maleic acid-modified polyolefin in boiled xylene, the measurement sample was reprecipitated in acetone from the obtained solution. Then, the precipitate was vacuum-dried at 80° C. for 6 hours to obtain a powdery sample.

A film having a thickness of 100 μm was produced by hot pressing the obtained sample. According to the ratio of the absorption peak appearing at 1780 cm ^-1 to the absorption peak appearing at 840 cm ^-1 in the infrared absorption spectrum of the obtained film and the calibration curve of Iide et al. (Reference: Polymer Chemistry 25, 167, 1968), the graft modification rate (mol%) was calculated by the following formula. [Graft modification rate]=[1780cm ^-1 absorbance]/[840cm ^-1 absorbance]×1.30

In addition, the obtained graft modification rate (mol %) can be converted into a graft modification rate (mass %) based on the calibration curve calculated|required separately. For example, a film having a thickness of 100 μm is prepared by preparing various mixtures of polypropylene and maleic anhydride while changing the formulation, and hot pressing each mixture. The above-mentioned graft modification rate (mol %) was measured for each of the obtained films, whereby a graph representing the correspondence between the content rate (mass %) of maleic anhydride contained in the film and the graft modification rate (mol %) can be prepared. Calibration line.

[Measurement method 3] The acid value of the measurement sample of maleic acid-modified polyolefin can also be obtained by the oxidation measurement method according to JIS (Japanese Industrial Standards) K 0070, and the obtained acid value can be converted by the following formula. The graft modification rate (mass %) was obtained. [Graft modification rate]=[Acid value of maleic acid modified polyolefin]÷11.4

For the measurement of the acid value, the following samples and reagents were used. Sample size: 1g to 2g (fine scale) Solvent: xylene (special grade reagent) Indicator: Phenolphthalein Titrate: 0.05mol/L KOH benzyl alcohol solution. Preliminarily titrate with 0.1 ml/L hydrochloric acid to obtain an accurate concentration.

First, 70 ml of a sample and a solvent were added to a 100-ml Erlenmeyer flask, an air cooling tube was attached, and the sample was heated in an oil bath at 135° C. for 15 minutes to obtain a xylene solution of the sample.

Then, 3 drops of indicator were added to the obtained sample and titrated on a hot stirrer at about 100°C. The end point of the titration was taken when the light red color persisted for 30 seconds. A blank test was also performed by the same method, and the acid value was calculated from the following formula. Acid value (mgKOH/g)=[(V ₁ -V _o )×N×56.11]/S V ₁ : The amount of titrant in the sample (ml) V ₀ : The amount of titrant in the blank test (ml) N: Titration Liquid concentration (mol/L) S: sample mass (g)

·Melt viscosity The melt viscosity of the maleic acid-modified polyolefin at the measurement temperature of 180°C is preferably 1000 mPa·s or more and 50000 mPa·s or less, more preferably 5000 mPa·s or more and 20000 mPa·s or less. The upper limit value and the lower limit value of the melt viscosity can be arbitrarily combined.

In this specification, melt viscosity means the value measured by the method based on JIS K7199. Specifically, it refers to a value when measured using a rheometer (manufactured by AntonPaar, device name: physicaMCR301) at a measurement temperature of 180° C., a strain amplitude of 3%, and a frequency of 1 Hz.

The melting point of the maleic acid-modified polyolefin is preferably 60°C or higher and 130°C or lower. The melting point is preferably 70°C or higher and 120°C or lower, more preferably 75°C or higher and 110°C or lower, and still more preferably 80°C or higher and 100°C or lower.

The weight-average molecular weight of the maleic acid-modified polyolefin is not particularly limited.

[Crosslinking agent: epoxy group-containing resin] Next, the crosslinking agent of the matrix resin for fiber-reinforced resin is demonstrated. Examples of epoxy group-containing resins used as crosslinking agents include bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol type epoxy resins, novolak type epoxy resins, and phenol novolac type epoxy resins. Oxygen resin, glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, etc. Phenoxy resin is a polyhydroxy polyether resin synthesized from bisphenols and epichlorohydrin. When the phenoxy resin has an epoxy group derived from epichlorohydrin as a raw material in the structure, it can be used as a crosslinking agent.

As the epoxy group-containing resin, a phenol type epoxy resin, a novolak type epoxy resin, and a phenol novolak type epoxy resin are preferable, and a phenol novolak type epoxy resin is more preferable.

Moreover, as an epoxy group-containing resin, a bisphenol A type epoxy resin and a bisphenol F type epoxy resin are also preferable. Here, the bisphenol A epoxy resin refers to an epoxy resin having a bisphenol A skeleton. Likewise, the bisphenol F type epoxy resin refers to an epoxy resin having a bisphenol F skeleton.

Bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin are compounds having a bisphenol compound as a basic structure, and an epoxy group is introduced into a part of the structure. The bisphenol compound has two phenolic hydroxyl groups, so the bisphenol epoxy resin is usually a bifunctional epoxy resin having a bisphenol skeleton.

In this specification, the so-called phenol novolak-type epoxy resin is a compound having a phenol novolak resin as a basic structure, and an epoxy group is introduced into a part of the structure. In general, phenol novolac resin is also referred to as "novolak" for short, and is obtained by condensing phenolic compounds and formaldehyde. The amount of epoxy group introduced per molecule in the phenol novolac epoxy resin is not particularly limited, but by reacting epoxy group raw materials such as epichlorohydrin with the phenol novolak resin, a large amount of the epoxy group present in the phenol novolak can be reduced. The phenolic hydroxyl group in the resin is generally a polyfunctional epoxy resin because a large number of epoxy groups are introduced.

The phenolic compound constituting the phenol novolak resin may be any compound as long as it has a phenolic hydroxyl group, and preferably a compound having no active hydrogen other than the hydroxyl group. Specific examples of the phenolic compound include monophenol compounds such as phenol (hydroxybenzene), cresol, and naphthol; and bisphenol compounds such as bisphenol A, bisphenol E, and bisphenol F. The phenol novolak resin and the phenol novolak epoxy resin constituted using a bisphenol compound have a bisphenol skeleton.

As the crosslinking agent, a phenol novolak-type epoxy resin having a bisphenol skeleton is preferred, and a phenol novolak-type epoxy resin having a bisphenol A skeleton or a bisphenol F skeleton is particularly preferred.

The epoxy equivalent of the epoxy group-containing resin is preferably 100 to 300, more preferably 200 to 300. The epoxy equivalent weight (g/eq) corresponds to the weight average molecular weight of one epoxy group contained in the epoxy group-containing resin, and the smaller the value, the more epoxy groups in the epoxy group-containing resin. By using the epoxy group-containing resin with a relatively small epoxy equivalent as the crosslinking agent, even if the epoxy group-containing resin is added in a relatively small amount, the maleic acid-modified polyolefin as the main agent is still used. Fully cross-linked.

The weight average molecular weight of the epoxy group-containing resin constituting the crosslinking agent is preferably 300 or more and 50,000 or less, preferably 10,000 or less. When the weight-average molecular weight of the epoxy compound is 50,000 or less, the epoxy compound is easily diffused and easily moved in the main agent. Therefore, if the weight-average molecular weight of the epoxy group-containing resin is below the above-mentioned upper limit, the epoxy group of the crosslinking agent (epoxy group-containing resin) and the main agent (maleic acid-modified polyolefin) ) has an increased reaction probability of the substituents.

In addition, when the weight-average molecular weight of the epoxy group-containing resin is below the above-mentioned upper limit value, when a fiber-reinforced resin is obtained by using the matrix resin for fiber-reinforced resin, the epoxy group contained in the crosslinking agent and the surface of the fiber The reaction probability of the substituents increases.

Due to these circumstances, the strength of the carbon fiber-reinforced resin molded body is improved.

As specific examples of phenol novolac epoxy resins, jER (registered trademark) 154, jER (registered trademark) 157S70, and jER (registered trademark) 157S65 manufactured by Mitsubishi Chemical Corporation; Commercially available products such as EPICLON (registered trademark) N-730A, EPICLON (registered trademark) N-740, EPICLON (registered trademark) N-770, and EPICLON (registered trademark) N-775 (all of the above are trade names).

The matrix resin for fiber-reinforced resin may contain, in addition to the main agent and the cross-linking agent, additives that are miscible with the main agent and the cross-linking agent, additive resins, plasticizers, stabilizers, colorants, etc. as appropriate. .

[mixing ratio] The solid content of the main ingredient is 80% by mass or more and 99.5% by mass or less, more preferably 85% by mass or more and 99% by mass or less, based on the total amount of the matrix resin for fiber-reinforced resin. The solid content concentration of the crosslinking agent is 0.5 mass % or more and 20 mass % or less, more preferably 1.0 mass % or more and 15 mass % or less, relative to the total amount of the matrix resin for fiber-reinforced resin.

When the ratio of the crosslinking agent is too large, it may be difficult to set appropriate bonding conditions. In the absence of a crosslinking agent, the maleic acid-modified polyolefin is not crosslinked, and the matrix resin is not hardened.

[Matrix resin film for fiber-reinforced resin] The matrix resin film for fiber-reinforced resin according to the present embodiment (hereinafter sometimes referred to as "resin film") is composed of the above-described matrix resin for fiber-reinforced resin according to the present embodiment.

As a method of forming a resin film, the method of manufacturing the coating liquid containing the said main ingredient and a crosslinking agent, apply|coating a coating liquid on a base material film, and drying is mentioned.

The film thickness after drying of the resin film is 10 μm or more and 200 μm or less. The film thickness of the resin film is preferably 20 μm or more and 150 μm or less, more preferably 30 μm or more and 100 μm or less, and most preferably 40 μm or more and 80 μm or less.

The coating liquid is preferably a coating liquid obtained by dissolving the main agent and the crosslinking agent in a solvent. Typically, such a coating liquid is prepared by dissolving the matrix resin for fiber-reinforced resin of the present embodiment in a solvent. The solvent is preferably an organic solvent excellent in the solubility of the main agent and the crosslinking agent and also in the drying properties after coating. The boiling point of the solvent is preferably, for example, 150°C or lower.

Specific examples of the solvent include toluene, xylene, anisole, ethylbenzyl ether, tolyl methyl ether, diphenyl ether, dibenzyl ether, phenethyl ether, butylphenyl ether, ethylbenzene, Aromatic hydrocarbon solvents such as diethylbenzene, pentylbenzene, cumene, cumene, and mesitylene.

Moreover, as a specific example of a solvent, aliphatic hydrocarbon solvents, such as n-hexane, are mentioned.

In addition, specific examples of the solvent include ketone-based solvents such as acetone, methyl ethyl ketone, cyclohexanone, methyl n-amyl ketone, methyl isoamyl ketone, and 2-heptanone.

In addition, specific examples of the solvent include methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl acetate Ester-based solvents such as ethyl oxypropionate.

In addition, specific examples of the solvent include alcohol-based solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol.

The solvent used for the coating liquid may be used alone or in combination of two or more of the above-mentioned solvents.

When a mixed solvent of two or more solvents is used in combination, it is also preferable to use an organic solvent that dissolves the main agent well and an organic solvent that dissolves the crosslinking agent well in combination. Such a combination is preferably a combination of toluene that dissolves the main agent well, and methyl ethyl ketone that dissolves the crosslinking agent well.

The manufacturing method of the coating liquid using a mixed solvent may be the method of dissolving a main agent and a crosslinking agent in a mixed solvent, and the method of mixing the solution of a main agent and the solution of a crosslinking agent may be sufficient.

The mixing ratio in the mixed solvent is not particularly limited as long as the main agent and the crosslinking agent can be dissolved favorably. For example, in the case of combining toluene and methyl ethyl ketone, the mass ratio is preferably 60:40 to 95:5, more preferably 70:30 to 90:10.

In addition, the resin film can also be produced by melt extrusion using a known sheet die or T-die. Compared with the above-mentioned method of applying and drying the coating liquid and producing, such a method can easily increase the thickness of the produced resin film.

The measured value E′ (150° C.) of the viscoelastic coefficient of the resin film at a measurement temperature of 150° C. is preferably 1.0×10 ³ Pa or more and 1.0×10 ⁶ Pa or less. E' (150 degreeC) can be evaluated by measuring the storage elastic coefficient at 150 degreeC using a well-known dynamic viscoelasticity measuring apparatus, for example. As a dynamic viscoelasticity measuring apparatus, the dynamic viscoelasticity measuring apparatus "RSA-3" (trade name) of TA Instruments, etc. can be used. The vibration frequency when the storage elastic coefficient is measured is, for example, 1 Hz.

The graph of the storage elastic coefficient obtained by the above-mentioned measurement is preferably the following graph: from the glass state in the low temperature region, through a transition region in which the measured value E' gradually decreases as the temperature rises, and reaches an equilibrium region approximately equal to the equilibrium value.

The value of E' (150°C) can be adjusted by the graft modification rate of the maleic acid-modified polyolefin constituting the resin film, or the addition amount of the crosslinking agent.

[Complex] The composite system of the present embodiment includes the resin film and the fiber material of the present embodiment described above. In the composite of this embodiment, the fiber material is preferably carbon fiber, aramid fiber, or glass fiber.

[prepreg] The present embodiment is a prepreg, and the prepreg system includes the matrix resin film for fiber-reinforced resin of the present embodiment described above, and carbon fibers. FIG. 1 is a schematic cross-sectional view showing a prepreg of the present embodiment. As shown in FIG. 1 , the prepreg 1 of this embodiment includes a resin layer 10 and a carbon fiber layer 20 .

In the prepreg 1, the resin layer 10 is composed of the above-mentioned matrix resin for fiber-reinforced resin.

[carbon fiber] The carbon fiber layer 20 is composed of a plurality of carbon fibers 29 buried in the resin layer 10 . The gaps 20a between the plurality of carbon fibers 29 are impregnated with a matrix resin for fiber-reinforced resin constituting the resin layer 10.

Carbon fiber is a general term for fibrous carbon materials consisting essentially only of carbon elements. In the manufacturing method of the prepreg of the present embodiment, generally known carbon fibers such as pitch-based carbon fibers and PAN (Polyacrylonitrile; polyacrylonitrile)-based carbon fibers can be used as the carbon fibers 29 .

The carbon fibers 29 used in this embodiment are continuous fibers. The carbon fiber layer 20 can also be a bundle of carbon fibers 29 that are continuous in one direction. Such carbon fibers 29 may be single fibers or twisted yarns. The term "continuous fibers" here refers to fiber bundles that are continuous throughout the entire length of the prepreg.

In addition, the carbon fiber layer 20 may be a woven fabric or a knitted fabric formed by using the carbon fibers 29 as continuous fibers. Woven fabrics may adopt commonly known weaving methods such as plain weave, twill weave, and satin weave.

The carbon fiber layer 20 is preferably a woven fabric using PAN-based carbon fibers as the carbon fibers 29 .

[Manufacturing method of prepreg] FIG. 2 and FIG. 3 are explanatory diagrams explaining the manufacturing steps of the prepreg. First, as shown in FIG. 2 , the carbon fiber sheet 21 is sandwiched by a pair of resin films 11 , and is pressed and bonded together.

[resin film] As the resin film 11, the resin film of the present embodiment described above was used.

[Carbon fiber sheet] The carbon fiber sheet 21 is a molded body obtained by molding carbon fiber into a sheet shape. As the carbon fiber sheet 21, for example, a woven fabric or a knitted fabric formed by using the carbon fibers 29 as continuous fibers described above can be used. Woven fabrics may adopt commonly known weaving methods such as plain weave, twill weave, and satin weave. In addition, the carbon fiber sheet 21 may be, for example, a woven fabric having the same shape as the carbon fiber layer 20 described above.

The resin film 11 is crimped to the carbon fiber sheet 21, and the laminated body 1B which consists of the resin film 11, the carbon fiber sheet 21, and the resin film 11 is obtained.

Then, as shown in FIG. 3 , the resin film 11 is heated to a temperature range not less than the softening point (softening temperature) of the resin film 11 and less than the reaction initiation temperature of the crosslinking agent contained in the resin film 11, so that the resin film 11 is heated. molten. Furthermore, the melted resin film 11 is pressed toward the carbon fiber sheet 21 . The “softening point of the resin film 11 ” is the softening point of the matrix resin for fiber-reinforced resin constituting the resin film 11 .

Thereby, in the laminated body 1B, the melted resin film 11 penetrates into the gaps 20 a of the plurality of carbon fibers 29 constituting the carbon fiber sheet 21 . Thereby, the prepreg 1 is produced.

The obtained prepreg 1 may also be cooled after pressing. In the resin film 11 heated until it melts, the crosslinking agent contained in the resin film 11 may undergo a crosslinking reaction unexpectedly by heating, and may be hardened. By cooling the prepreg 1, the above-mentioned unexpected crosslinking reaction can be suppressed or stopped.

[Carbon fiber reinforced resin molded body] The present embodiment is a carbon fiber-reinforced resin molded body formed by laminating the prepregs of the present embodiment described above. In the following description, the carbon fiber-reinforced resin molded body may be simply referred to as a "molded body".

[Manufacturing method of carbon fiber reinforced resin molded body] The manufacturing method of the carbon fiber reinforced resin molded body of this embodiment includes the following steps: a step of laminating a prepreg to obtain a laminated body; and a step of subjecting the obtained laminated body to press molding.

The obtained prepreg 1 of this embodiment can be used as a punched sheet. The prepreg 1 can be molded by heating, and a molded body can be produced. More specifically, a laminate formed by laminating only one or more sheets of prepreg 1 can be heated and softened, and the softened prepreg 1 can be pressed with a mold to form, that is, so-called press forming. This produces a molded body.

Further, the prepreg 1 is heated to a temperature equal to or higher than the reaction initiation temperature of the crosslinking agent contained in the resin layer 10 , so that the crosslinking reaction of the main agent constituting the resin layer 10 and the crosslinking agent proceeds and is cured. Thereby, the target molded body can be obtained.

According to the prepreg having the above-described configuration, a carbon fiber reinforced resin molded body having good mechanical strength and appearance can be produced using carbon fiber reinforced resin as a forming material.

Moreover, according to the manufacturing method of the carbon fiber reinforced resin molded object as mentioned above, the carbon fiber reinforced resin molded object of high quality can be manufactured easily.

As mentioned above, although the suitable embodiment example of this invention was demonstrated referring an accompanying drawing, this invention is not limited to this example. The various shapes, combinations, etc. of the respective constituent members shown in the above examples are examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention. [Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[Measuring method of melt viscosity] Melt viscosity means the value measured by the method based on JIS K7199. Specifically, it refers to a value when measured using a rheometer (manufactured by Anton Paar, device name: physicaMCR301) at a measurement temperature of 180° C., a strain amplitude of 3%, and a frequency of 1 Hz.

[Measurement method of viscoelasticity] The viscoelastic coefficient was measured using the device name: viscoelasticity measuring device, model: RSA-3 manufactured by TA Instrument. For the measurement, resin films produced in Examples and Comparative Examples to be described later were used. In the measurement, a test piece processed into a resin film with a width of 5 mm x 4 cm was used. The coefficient of viscoelasticity is to use a clamp to clamp the upper and lower ends of the test piece by 1 cm at each end, and measure the dynamic viscoelasticity value caused by stretching for the test piece with a length of 2 cm. The measurement was performed while the vibration frequency at the time of measurement was set to 1 Hz, and the temperature was gradually increased from 25°C to 180°C at 3°C/min. For example, in the case of E' (150°C), the value of the elastic modulus when the temperature reaches 150°C when the temperature is gradually increased.

[Method for Determination of Graft Modification Rate] A film with a thickness of about 100 μm is produced by hot pressing a granular sample of maleic anhydride, and the absorption peak appears at 1780 cm ⁻¹ in the infrared absorption spectrum to detect the mass. The amount of maleic acid was determined, and the obtained value was taken as the total amount of maleic anhydride. Let the obtained value be A.

After dissolving the granular measurement sample in boiled xylene, the measurement sample was reprecipitated in methanol from the obtained solution. Then, the precipitate was vacuum-dried at 80° C. for 6 hours to obtain a powdery sample.

The amount of maleic anhydride contained in the obtained sample was measured by the same method as above, and the obtained value was taken as the amount of maleic anhydride grafted to the polyolefin in the sample. Let the obtained value be B.

Divide the amount of graft-modified maleic anhydride (B) by the total amount of maleic anhydride (A), express the obtained value as a percentage, and use the value expressed as a percentage ((B/A)×100 ) as the graft modification rate (mass %) of the maleic acid-modified polyolefin obtained from maleic anhydride in the measurement sample.

[Example 1 to Example 9, Comparative Example 1 to Comparative Example 4] The resin film was manufactured by the structure shown in Table 1. Specifically, the toluene solution of the maleic acid-modified polypropylene-based resin and the crosslinking agent as the main ingredients was coated on the PET (Polyethylene terephthalate; polyethylene terephthalate) subjected to the mold release treatment by bar coating. Glycol) substrate film, and dried to obtain a resin film. The film thicknesses of the resin films were all set to the film thicknesses shown in Table 1, respectively.

The carbon fiber sheets shown in Table 1 were sandwiched between two of the obtained resin films to form a laminate, and the obtained laminate was heated and pressurized under the following conditions to produce a prepreg. The thickness of the prepreg is recorded in Table 1, respectively. Heating: 180℃ Pressurization: 0.5t per 30cm ² square load time: 1 minute

[Table 1] Matrix resin film Prepreg basic resin Additive 1 Additive 2 Viscoelasticity measured value (150℃) Film thickness type Melt viscosityPa s (180℃) Grafting modification rate (grafting rate/mass%) added amount resin added amount type added amount Types of carbon fiber Prepreg Thickness Example 1 Maleic acid modified polypropylene 7000 2.0 97 Epoxy 1 3 - - 1.6×10 ⁴ 55 CF1 125μm Example 2 Maleic acid modified polypropylene 7000 2.0 96.5 Epoxy 1 3 Isocyanate 0.5 4.3×10 ⁴ 55 CF1 125μm Example 3 Maleic acid modified polypropylene 7000 2.0 97 Epoxy 1 1 - - 1.3×10 ⁴ 55 CF1 125μm Example 4 Maleic acid modified polypropylene 7000 2.0 97 Epoxy 2 3 - - 2.0×10 ⁴ 55 CF1 125μm Example 5 Maleic acid modified polypropylene 20000 1.9 97 Epoxy 1 3 - - 6.0×10 ⁵ 55 CF1 125μm Example 6 Maleic acid modified polypropylene 7000 2.0 82 Epoxy 1 18 - - 5.8×10 ⁵ 55 CF1 123μm Example 7 Maleic acid modified polypropylene 7150 0.6 97 Epoxy 1 3 - - 1.3×10 ⁴ 55 CF1 123μm Example 8 Maleic acid modified polypropylene 7210 2.7 97 Epoxy 1 3 - - 6.3×10 ⁴ 55 CF1 122μm Example 9 Maleic acid modified polypropylene 7000 2.0 97 Epoxy 1 3 - - 1.6×10 ⁴ 180 CF2 330μm Comparative Example 1 Maleic acid modified polypropylene 8500 2.0 100 - - - - 1.1×10 ² 55 CF1 126μm Comparative Example 2 Maleic acid modified polypropylene 7350 0.3 100 Epoxy 1 3 - - 8.5×10 ³ 55 CF1 123μm Comparative Example 3 Maleic acid modified polypropylene 7000 2.0 50 Epoxy 1 50 - - 5.5×10 ⁶ 55 CF1 123μm Comparative Example 4 epoxy resin composition 100 - - - - - 60 CF1 150μm

Each material shown in Table 1 is as follows, respectively.

Maleic acid modified polypropylene: the graft modification rate obtained from maleic acid is 1.2%, weight average molecular weight=120,000, melting point=80℃ Epoxy resin composition: epoxy resin obtained by kneading bisphenol A epoxy resin, tetraglycidyl diamino diphenyl methane, 4,4'-diamino diphenyl selenium and polyether selenium resin composition CF1: Carbon fiber plain fabric (trade name: Torayca cloth CO-6363, manufactured by Toray Co., Ltd.) CF2: Carbon fiber plain fabric (trade name: Torayca cloth CO-6141, manufactured by Toray Co., Ltd.) Epoxy 1: "jER157S70" (trade name, manufactured by Mitsubishi Chemical Corporation) (phenol novolac epoxy resin with bisphenol A structure; viscosity=80; epoxy equivalent=210) Epoxy 2: "jER154" (trade name, manufactured by Mitsubishi Chemical Corporation) (phenol novolak type epoxy resin; viscosity=80; epoxy equivalent=180)

[Evaluation of Takt Time] The time (takt time) required for pressing and heating until the molded body is hardened during press forming was evaluated according to the following items. "◎": The molded body was sufficiently cured by heating and pressurizing within 30 seconds. "O": The molded body is sufficiently hardened by heating and pressing for more than 30 seconds to within 1 minute. "△": The molded body is sufficiently hardened by heating and pressing for more than 1 minute to within 3 minutes. "X": The molded body was sufficiently hardened by heating and pressurizing for more than 3 minutes to within 5 minutes. "XX": The molded body was sufficiently hardened by heating and pressing for more than 5 minutes.

In the takt time evaluation, "◎", "〇", and "△" were set as good products, and "×" and "XX" were set as defective products. The evaluation results are shown in Table 2.

[Production of Compression Forming Sheet] Small pieces of 210 mm square were cut out from the obtained prepreg. The cut out pieces were stacked and placed in the center of a 300 mm square flat plate forming mold, heated and pressurized at 140° C. and 10 MPa for 5 minutes to obtain a 300 mm square compression-formed plate with a thickness of about 4 mm. The compression-molded sheet corresponds to the carbon fiber-reinforced resin molded body in the present invention.

[Evaluation of void ratio] The cross section of the compression-formed sheet was observed, and the void ratio was evaluated as follows. First, the compression-molded sheet is cut in a direction intersecting the fiber direction of the carbon fibers to form a surface in which both carbon fibers and resin are present in the cross-section of the compression-molded sheet, and the carbon fibers appear to be circular.

Next, with respect to the range of 100 micrometers x 100 micrometers of the said cross-section, the magnification image of the magnification of 20 times was photographed using an electron microscope (Digital Microscope VHX of Keynes Corporation). The obtained image was image-processed using the image processing software attached to the electron microscope, and the void ratio was calculated. The calculation method of a void ratio is performed as follows.

Regarding the image obtained by photographing, the area excluding the carbon fibers that appear to be circular is regarded as a resin portion or a gap portion where resin is not penetrated.

The boundary between the resin portion and the gap portion is determined by the change in the brightness of the image. That is, a set of parts whose contrast ratio is suddenly darker than the vicinity of the adjoining part is regarded as a gap part, and the other parts are regarded as a resin part. Here, the sudden darkening refers to a point at which the lightness becomes 3 times or less when moved by 0.5 μm from an arbitrary point. This is a set of parts that will be darkened in a certain range and a certain range as a gap part.

More specifically, evaluation was performed as follows. First, orthogonal coordinate axes (x-axis, y-axis) are set in the obtained image. Next, the brightness of the pixels constituting the image was discretely obtained along the x-axis at intervals of 0.5 μm in the cross section. Among the multiple points for which the lightness was obtained, the space between two adjacent points having a difference of three times or more in lightness was taken as the boundary point between the gap portion and the resin portion.

In the y-axis direction, the same operation was performed on the entire area of the image at intervals of 0.5 μm, and the boundary line between the gap portion and the resin portion was drawn based on the obtained plurality of boundary points. The side with high lightness across the drawn boundary line was defined as a resin portion, and the side with low lightness was defined as a gap portion.

By image processing using an image processing software, the area Sp of the resin portion and the area Sv of the gap portion are obtained in the area where the carbon fibers appearing to be circular are excluded in the captured image.

Using the obtained areas Sv and Sp, the ratio of the gap portion was calculated as a percentage from the following formula (1). The ratio of voids=area Sv/(area Sv+area Sp)×100… Equation (1)

The above-mentioned photographing, image processing, and calculation of the ratio of the gap portion were performed five times in total, and the average value (n=5) of the ratio of the gap portion obtained was used as the "void ratio".

The obtained porosity was evaluated according to the following items. "◎", "〇", and "△" were rated as good products, and "×" as defective products for evaluation. "◎": The void ratio was less than 0.3%. "○": The void ratio is 0.3% or more and less than 0.7%. "△": The void ratio is 0.7% or more and less than 3%. "X": The void ratio is 3% or more.

In the evaluation of the porosity, "⊚", "○", and "△" were regarded as good products, and "×" was regarded as defective products. The evaluation results are shown in Table 2.

[Appearance evaluation] The surface state of the compression-molded plate was visually confirmed and the touch feeling was confirmed, and the evaluation was performed according to the following criteria. "◎", "〇", and "△" were regarded as good products, and "×" and "XX" were regarded as defective products for evaluation. "⊚": The surface is smooth to the touch over the entire surface of the formed plate, and is glossy in the visual evaluation. "○": The surface was smooth to the touch over the entire surface of the formed plate, but was dull in visual evaluation. "△": A part of the surface of the formed plate was rough to the touch, and was dull in visual evaluation. "X": The surface was rough to the touch over the entire surface of the formed plate, and was dull in visual evaluation. "XX": The surface was very rough to the touch over the entire surface of the formed plate, and was dull in visual evaluation.

In the appearance evaluation, "◎", "○", and "△" were regarded as good products, and "×" and "XX" were regarded as defective products. The evaluation results are shown in Table 2.

[Table 2] Evaluation void ratio Takt time Appearance evaluation Example 1 ◎ ◎ ◎ Example 2 ◎ ◎ ◎ Example 3 〇 〇 〇 Example 4 〇 〇 〇 Example 5 〇 △ 〇 Example 6 ◎ ◎ ◎ Example 7 〇 〇 △ Example 8 〇 〇 〇 Example 9 △ 〇 ◎ Comparative Example 1 〇 ◎ ×× Comparative Example 2 △ 〇 × Comparative Example 3 × 〇 × Comparative Example 4 ◎ ×× ◎

As a result of the evaluation, it was found that the prepregs of the examples were superior in appearance, had fewer voids, and could be cured in a short time, compared with the prepregs of the comparative examples.

1: Prepreg 1B: Laminate 10: Matrix resin 11: Resin film 20: Carbon fiber layer 20a: Gap 21: Carbon fiber sheet 29: Carbon Fiber

Fig. 1 is a schematic cross-sectional view showing a prepreg. [ Fig. 2] Fig. 2 is an explanatory diagram for explaining the manufacturing steps of the prepreg. [ Fig. 3] Fig. 3 is an explanatory diagram for explaining the manufacturing steps of the prepreg.

Claims (13)

A matrix resin for fiber-reinforced resin, which is composed of a resin composition containing a main agent and a cross-linking agent, wherein the main agent is a maleic acid-modified polymer graft modified by maleic anhydride or maleic acid. It is composed of olefin, and the aforementioned crosslinking agent is composed of epoxy group-containing resin; The graft modification rate of the maleic acid-modified polyolefin obtained from the maleic anhydride or the maleic acid is 0.5 mass % or more and 3.0 mass % or less; With respect to the total amount of the matrix resin for fiber-reinforced resin, the solid content concentration of the aforementioned main agent is 80% by mass or more and 99.5% by mass or less; The solid content concentration of the aforementioned crosslinking agent is 0.5 mass % or more and 20 mass % or less with respect to the total amount of the matrix resin for fiber-reinforced resin. The matrix resin for fiber-reinforced resin according to claim 1, wherein the maleic acid-modified polyolefin has a melt viscosity of 1,000 mPa·s or more and 50,000 mPa·s or less at 180°C. The matrix resin for fiber-reinforced resin according to claim 1 or 2, wherein the graft modification ratio is 0.5 mass % or more and 2.5 mass % or less. The matrix resin for fiber-reinforced resin according to claim 1 or 2, wherein the epoxy group-containing resin has a weight average molecular weight of 300 or more and 50,000 or less. The matrix resin for fiber-reinforced resin according to claim 1 or 2, wherein the epoxy group-containing resin is selected from the group consisting of novolac type, phenol type, bisphenol A type, and bisphenol F type more than one. A matrix resin film for fiber-reinforced resin, which is composed of the matrix resin for fiber-reinforced resin according to any one of claims 1 to 5, and has a film thickness of 10 μm or more and 200 μm or less. The matrix resin film for fiber-reinforced resin according to claim 6 has a dynamic storage viscoelastic coefficient (E') obtained by measuring dynamic viscoelasticity at 150° C. of 1.0×10 ⁴ Pa or more and 1.0×10 ⁶ Pa or less. A composite comprising the matrix resin film for fiber-reinforced resin according to claim 6 or 7, and a fiber material. The composite according to claim 8, wherein the fiber material is carbon fiber, aramid fiber, or glass fiber. A prepreg comprising the matrix resin film for fiber-reinforced resin according to claim 6 or 7, and carbon fibers. The prepreg according to claim 10, wherein the carbon fibers are continuous fibers. A carbon fiber reinforced resin molded body obtained by laminating the prepreg as described in claim 10 or 11. A method of manufacturing a carbon fiber reinforced resin molded body, which is to manufacture a carbon fiber reinforced resin molded body formed by laminating the prepregs as described in claim 10 or 11, comprising the following steps: the step of laminating the prepregs to obtain a laminate; and The step of subjecting the obtained laminated body to press forming.

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