JP2019181929A - Prepreg and manufacturing method thereof - Google Patents

Abstract

To provide a thick prepreg having excellent impregnation property and surface smoothness for suppression of laminate sheet thickness unevenness and reduction of lamination time.SOLUTION: The invention provides a prepreg comprising uniaxially aligned carbon fibers impregnated with a thermosetting resin composition, wherein the fiber weight (FAW(g/m)) per unit area of the prepreg is 250-400 g/mand, when a width of the prepreg is A (m), the difference of the maximum irregularity of the prepreg surface is Rt (μm), a yarn width of the carbon fiber y is B(m), and a weight of the fiber per unit length of the carbon fiber is C (g/m), the prepreg satisfies the following formulae (1) and (2); 2A≥(FAW/C)×B≥A (1); Rt≤70+0.4(FAW-250) (2).SELECTED DRAWING: None

Description

  The present invention relates to a thick prepreg that provides a molded product with small thickness variation in a prepreg that is an intermediate substrate for producing a fiber-reinforced composite material suitable for sports use, aerospace use, general industrial use, and the like, and a method for producing the same. It is about.

  Fiber reinforced composite materials consisting of carbon fiber, glass fiber and other reinforcing fibers and epoxy resins, phenol resins and other thermosetting resins are used in sports fields such as golf clubs, tennis rackets and fishing rods because of their light weight and excellent mechanical properties. It is used in a wide range of fields including civil engineering and construction such as structural materials such as aircraft, spacecraft, automobiles, railway vehicles and ships, and repair and reinforcement of concrete structures. In many of the methods for obtaining fiber reinforced composite materials, a semi-cured intermediate base material in which continuous reinforced fibers called prepregs are impregnated with a thermosetting resin composition is used because of its handleability and shapeability. A method of laminating and curing the thermosetting resin composition by heating and pressing with an autoclave or the like is often used.

  In recent years, a method of shortening the prepreg lamination time using a so-called thick prepreg having a large carbon fiber basis weight has been used for the purpose of increasing the production efficiency of molded products.

  A molded body using a thick prepreg generally tends to have a large thickness variation. In recent years, there has been a problem that a yield is lowered while a demand for accuracy is increasing. In Patent Documents 1 to 3, various prepreg manufacturing methods are proposed.

JP 2002-30538 A Japanese Patent Laying-Open No. 2015-221867 Japanese Patent No. 5985391

  Patent Document 1 proposes a method for obtaining a unidirectional prepreg by opening a fiber bundle with a spreader bar as a prepreg manufacturing method. In this method, it is possible to uniformly spread a plurality of fiber bundles into a sheet shape, but the fiber opening and widening ability is not sufficient, and it is difficult to uniformly form the fibers into a sheet shape. Therefore, it is difficult to produce a thick prepreg that gives a molded product with small thickness variation.

  Patent Document 2 proposes a method of obtaining a unidirectional prepreg by defining carbon fibers to be used, bringing carbon fibers whose tension is controlled into contact with a plurality of pass rolls, and applying vibration. In this method, it is possible to obtain a molded body with little design of single yarn fluff on the surface of the molded body and excellent design, but the fiber opening and widening ability is not sufficient, and the fibers are uniformly formed into a sheet shape. Therefore, it is difficult to manufacture a thick prepreg that gives a molded product with small thickness variation.

  Patent Document 3 proposes a production method that defines the viscosity of a thermosetting resin composition and obtains a thick prepreg with few voids. In this method, it is possible to produce a thick prepreg that is excellent in impregnation and handling properties, but the fiber opening and widening ability is insufficient, and it is difficult to make the fiber into a sheet shape uniformly. It is difficult to produce a thick prepreg that gives a compact with small variations.

  As described above, with the conventional technology, it has been difficult to produce a thick prepreg that gives a molded product with small thickness variation.

In order to solve the above-mentioned problems, the prepreg of the present invention is a prepreg formed by impregnating a thermosetting resin composition with carbon fibers aligned in one direction, and has a fiber basis weight per unit area of the prepreg ( FAW (g ^{/ m} 2)) is a 250~400g / ^{m 2,} and the prepreg width a (m), the maximum unevenness difference of the prepreg surface Rt ([mu] m), the yarn width of the carbon fiber is B (m) When the fiber basis weight per unit length of the carbon fiber is C (g / m), the prepreg satisfies the following formulas (1) and (2) at the same time.
2A ≧ (FAW / C) × B ≧ A (1)
Rt ≦ 70 + 0.4 (FAW−250) (2).

  Further, the prepreg manufacturing method of the present invention is a prepreg manufacturing method for manufacturing the prepreg described above, in which the pitch between carbon fibers is aligned with a comb, and adjacent carbon fibers are alternately passed through bars, and then heated. This is a method for producing a prepreg to be impregnated in a curable resin composition.

  ADVANTAGE OF THE INVENTION According to this invention, the thick article prepreg excellent in the surface smoothness which can reduce the thickness variation of a molded object is obtained.

FIG. 1 is a schematic view showing a molded body and measurement points of thickness variation.

  The carbon fiber of the present invention is not particularly limited, and pitch-based and polyacrylonitrile-based carbon fibers can be used, and two or more of these fibers may be mixed and used. Among these, it is preferable to use polyacrylonitrile-based carbon fiber from which a prepreg having a high tensile strength can be easily obtained.

  As a thermosetting resin composition used for the prepreg of the present invention, an epoxy resin is used as a main component because of excellent balance of heat resistance, mechanical properties and adhesion to carbon fibers.

  The epoxy resin is not particularly limited, and is not limited to bisphenol type epoxy resin, amine type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, resorcinol type epoxy resin, phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy. Select one or more of resin, dicyclopentadiene type epoxy resin, epoxy resin having biphenyl skeleton, isocyanate-modified epoxy resin, tetraphenylethane type epoxy resin, triphenylmethane type epoxy resin, diglycidyl aniline derivative, etc. Can be used.

  Here, the bisphenol type epoxy resin is obtained by glycidylation of two phenolic hydroxyl groups of a bisphenol compound. The bisphenol A type, bisphenol F type, bisphenol AD type, bisphenol S type, or halogens and alkyls of these bisphenols. Examples include substituted products and hydrogenated products. Moreover, not only a monomer but the high molecular weight body which has a some repeating unit can also be used. Among them, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin are preferably used because of a good balance between elastic modulus, toughness and heat resistance.

  Commercially available products of such bisphenol A type epoxy resins include “jER (registered trademark)” 825, 828, 834, 1001, 1002, 1003, 1003F, 1004, 1004AF, 1005F, 1006FS, 1007, 1009, 1010 (and above, Mitsubishi Chemical Co., Ltd.). Examples of the brominated bisphenol A type epoxy resin include “jER (registered trademark)” 505, 5050, 5051, 5054, and 5057 (above, manufactured by Mitsubishi Chemical Corporation). Examples of commercially available hydrogenated bisphenol A type epoxy resins include ST5080, ST4000D, ST4100D, ST5100 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

  Commercially available products of such bisphenol F type epoxy resins include “jER (registered trademark)” 806, 807, 4002P, 4004P, 4007P, 4009P, 4010P (manufactured by Mitsubishi Chemical Corporation), “Epototo (registered trademark)”. YDF2001, YDF2004 (above, Nippon Steel & Sumikin Chemical Co., Ltd.) etc. are mentioned. Examples of the tetramethylbisphenol F type epoxy resin include YSLV-80XY (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

  As a commercial item of this bisphenol S type epoxy resin, "Epiclon (trademark)" EXA-154 (made by DIC Corporation) etc. are mentioned.

  Examples of the amine type epoxy resin include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol, tetraglycidylxylylenediamine, halogens thereof, alkynol-substituted products, hydrogenated products, and the like.

  Examples of such tetraglycidyldiaminodiphenylmethane include “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and “jER (registered trademark)” 604 (Mitsubishi Chemical Corporation). And “Araldide (registered trademark)” MY720, MY721 (manufactured by Huntsman Advanced Materials Co., Ltd.). As triglycidylaminophenol or triglycidylaminocresol, “Sumiepoxy (registered trademark)” ELM100, ELM120 (above, manufactured by Sumitomo Chemical Co., Ltd.), “Araldide (registered trademark)” MY0500, MY0510, MY0600 (above, Huntsman Advanzed Materials Co., Ltd.), “jER (registered trademark)” 630 (Mitsubishi Chemical Co., Ltd.), and the like. Examples of tetraglycidylxylylenediamine and hydrogenated products thereof include TETRAD-X and TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

  Commercially available products of such phenol novolac epoxy resins are “jER (registered trademark)” 152, 154 (manufactured by Mitsubishi Chemical Corporation), “Epiclon (registered trademark)” N-740, N-770, N-775. (Above, manufactured by DIC Corporation).

  Commercially available products of such cresol novolac type epoxy resins include “Epiclon (registered trademark)” N-660, N-665, N-670, N-673, N-695 (above, manufactured by DIC Corporation), EOCN- 1020, EOCN-102S, EOCN-104S (manufactured by Nippon Kayaku Co., Ltd.).

  Examples of commercially available resorcinol-type epoxy resins include “Denacol (registered trademark)” EX-201 (manufactured by Nagase ChemteX Corporation).

  NC-2000 (made by Nippon Kayaku Co., Ltd.) etc. are mentioned as a commercial item of this phenol aralkyl type epoxy resin.

  Commercially available products of such naphthol aralkyl type epoxy resins include “Epototo (registered trademark)” ESN-155, “Epototo (registered trademark)” ESN-355, “Epototo (registered trademark)” ESN-375, “Epototo (registered trademark)”. ) “ESN-475V”, “Epototo (registered trademark)” ESN-485, “Epototo (registered trademark)” ESN-175 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and the like.

  Commercially available products of such dicyclopentadiene type epoxy resins include “Epiclon (registered trademark)” HP-7200, HP-7200L, HP-7200H, HP-7200HH, HP-7200HHH (manufactured by DIC Corporation), “Tactix” (Registered trademark) "558 (manufactured by Huntsman Advanced Material Co., Ltd.), XD-1000-1L, XD-1000-2L (manufactured by Nippon Kayaku Co., Ltd.), and the like.

  Examples of commercially available epoxy resins having such a biphenyl skeleton include “jER (registered trademark)” YX4000H, YX4000, YL6616 (manufactured by Mitsubishi Chemical Corporation), NC-3000 (manufactured by Nippon Kayaku Co., Ltd.), and the like. Can be mentioned.

  Examples of such commercially available isocyanate-modified epoxy resins include XAC4151, AER4152 (produced by Asahi Kasei Epoxy Co., Ltd.) and ACR1348 (produced by ADEKA Co., Ltd.) having an oxazolidone ring.

  Examples of commercially available tetraphenylethane type epoxy resins include “jER (registered trademark)” 1031 (manufactured by Mitsubishi Chemical Corporation), which is a tetrakis (glycidyloxyphenyl) ethane type epoxy resin.

  Examples of such a commercial product of triphenylmethane type epoxy resin include “Tactics (registered trademark)” 742 (manufactured by Huntsman Advanced Materials).

  Examples of commercially available diglycidyl aniline derivatives include GAN (diglycidyl aniline) and GOT (diglycidyl toluidine, both manufactured by Nippon Kayaku Co., Ltd.).

  In the thermosetting resin composition of the present invention, a curing agent is preferably used in order to increase the curability of the prepreg.

  The curing agent is not particularly limited, and amines such as aromatic amines and alicyclic amines, phenol resins, dicyandiamide or derivatives thereof, acid anhydrides, polyaminoamides, organic acid hydrazides, and isocyanates may be used. Good.

  Such aromatic amines include xylenediamine, diaminodiphenylmethane, phenylenediamine, diaminodiphenylsulfone, and the like.

  Examples of such alicyclic amines include isophorone diamine and mensen diamine.

  Examples of such phenol resins include resins obtained by condensation of phenols such as phenol, cresol, xylenol, t-butylphenol, nonylphenol, cashew oil, lignin, resorcin, and catechol with aldehydes such as formaldehyde, acetaldehyde, and furfural. And novolak resins and resole resins. The novolak resin can be obtained by reacting phenol and formaldehyde in the same amount or in excess of phenol in the presence of an acid catalyst such as oxalic acid. The resole resin can be obtained by reacting phenol and formaldehyde in the same amount or in excess of formaldehyde in the presence of a base catalyst such as sodium hydroxide, ammonia or organic amine. Commercially available phenolic resins include “Sumilite Resin (registered trademark)” (manufactured by Sumitomo Bakelite Co., Ltd.), Resitop (manufactured by Gunei Chemical Industry Co., Ltd.), and “AV Light (registered trademark)” (Asahi Organic Materials). Kogyo Co., Ltd.).

  Examples of such commercially available dicyandiamide include DICY7 and DICY15 (manufactured by Mitsubishi Chemical Corporation).

  In order to adjust the viscoelastic properties, a thermoplastic resin may be blended in the thermosetting resin composition of the present invention as long as various properties are not impaired.

  As the thermoplastic resin, a thermoplastic resin soluble in an epoxy resin, organic particles such as rubber particles and thermoplastic resin particles, and the like can be blended. As the thermoplastic resin soluble in the epoxy resin, a thermoplastic resin having a hydrogen bonding functional group that can be expected to improve the adhesion between the resin and the carbon fiber is preferably used. Examples of the thermoplastic resin that is soluble in the epoxy resin and has a hydrogen bonding functional group include a thermoplastic resin having an alcoholic hydroxyl group, a thermoplastic resin having an amide bond, and a thermoplastic resin having a sulfonyl group. .

  Examples of the thermoplastic resin having an alcoholic hydroxyl group include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, and phenoxy resins. Examples of the thermoplastic resin having an amide bond include polyamide, polyimide, and polyvinylpyrrolidone. An example of the thermoplastic resin having a sulfonyl group is polysulfone. Polyamide, polyimide and polysulfone may have a functional group such as an ether bond and a carbonyl group in the main chain. The polyamide may have a substituent on the nitrogen atom of the amide group.

  Examples of commercially available thermoplastic resins that are soluble in epoxy resins and have hydrogen bonding functional groups include, as polyvinyl acetal resins, Denkabutyral and “Denka Formal (registered trademark)” (manufactured by Denki Kagaku Kogyo Co., Ltd.), “Vinylec (registered trademark)” (manufactured by JNC Corporation), “UCAR (registered trademark)” PKHP (manufactured by Union Carbide Corporation) as a phenoxy resin, and “Macromelt (registered trademark)” (Henkel Hakusui) as a polyamide resin ), “Amilan (registered trademark)” CM4000 (manufactured by Toray Industries, Inc.), “Ultem (registered trademark)” (manufactured by General Electric Co., Ltd.), “Matrimid (registered trademark)” 5218 (polyimide) Ciba Co., Ltd.), “Sumika Excel (registered trademark)” (manufactured by Sumitomo Chemical Co., Ltd.), “UD” as polysulfone L (registered trademark) "(manufactured by Solvay Advanced Polymers KK), as a polyvinylpyrrolidone," Luviskol (registered trademark) "can be exemplified (BASF Japan Ltd.).

  Moreover, acrylic resin has high compatibility with an epoxy resin, and is preferably used for controlling viscoelasticity. Examples of commercially available acrylic resins include “Dianal (registered trademark)” BR series (manufactured by Mitsubishi Chemical Corporation), “Matsumoto Microsphere (registered trademark)” M, M100, M500 (Matsumoto Yushi Seiyaku Co., Ltd.) And "Nanostrength (registered trademark)" E40F, M22N, M52N (manufactured by Arkema Co., Ltd.), and the like.

The prepreg of the present invention, to provide a molded article having a high thickness accuracy, per unit area of the prepreg fiber basis weight ^{(FAW (g / m 2)} ) is 250~400g / ^{m 2,} in view of the shortened stack time From 350 to 400 g / m ² is preferable. Furthermore, the prepreg width is A (m), the maximum unevenness of the prepreg surface is Rt (μm), the carbon fiber thread width is B (m), and the fiber basis weight per unit length of the carbon fiber is C (g / m). It is necessary to satisfy the following equations (1) and (2) at the same time.
2A ≧ (FAW / C) × B ≧ A (1)
Rt ≦ 70 + 0.4 (FAW−250) (2).

  In addition, the prepreg width here is a distance measured between carbon fibers on the outermost sides of the prepreg using a length measuring device such as a measure or a ruler.

  Moreover, the maximum unevenness | corrugation difference Rt of the prepreg surface here is defined as the maximum cross-sectional height of a roughness curve by JISB0601: 2001, and is measured as follows. Three points of prepregs cut to a width of 100 mm at equal intervals in the prepreg width direction are used as test pieces, and the surface smoothness of each test piece is measured with a contact-type surface roughness measuring instrument. As the contact-type surface roughness measuring instrument, for example, a surface roughness measuring instrument SE-3500 manufactured by Kosaka Laboratory Ltd. is used, and a detector is provided with a diamond needle having a stylus tip radius of 2 μm and a measuring force of 0. This is an average value of a total of 9 points, measured at 7 mN and measured 3 times with a width of 90 mm so as to be orthogonal to the fiber direction of each sample at a measurement speed of 2 mm / sec.

  The yarn width of the carbon fiber here is measured as follows. The carbon fiber wound around a paper tube or the like is pulled out 100 cm, and is stuck on a desk or the like with tape or the like in a state where no tension is applied. The width of the carbon fiber is measured by using a length measuring instrument such as a measure or a ruler in increments of 10 cm with one end as 0 cm. This is an average length of 11 points in total, which was repeated up to 100 cm including 0 cm.

  The fiber basis weight per unit length of carbon fiber here is generally called fineness, and is expressed by mass per 1000 m of single yarn (g / 1000 m: tex). In the present invention, “g / m” is handled as a unit of fineness.

  The prepreg of the present invention preferably has a FAW variation (CV value) in the width direction of 1.5% or less. If the FAW variation is 1.5% or less, it is easy to obtain a molded product having a small thickness variation.

  In addition, the dispersion | variation in FAW here is measured as follows. Using five prepregs cut at 100 mm in the width direction and 100 mm in the longitudinal direction as test pieces at equal intervals in the width direction of the prepreg, the resin impregnated in the prepreg was dissolved and extracted in an organic solvent, and the mass of the remaining carbon fiber was determined. It is derived from the measured average value and standard deviation.

  The prepreg of the present invention preferably has an impregnation rate of 10.0% or less measured using a water pickup method. In thick prepregs, it is difficult to impregnate the resin inside the carbon fiber, so that the fiber may burn or the fibers in the unimpregnated part may float, which may often be a problem during laminating work. By making the impregnation ratio of not more than 10.0%, the above problem can be easily reduced. In addition, the impregnation rate by the water pick-up method here is measured as follows. The mass W1 is measured in advance using five prepregs cut into 100 mm × 100 mm with two sides of 0 ° and 90 ° at equal intervals in the prepreg width direction as test pieces. One side of the prepreg is arranged with the fiber direction of the prepreg in the vertical direction, a range of 5 mm from the end (that is, 100 mm × 5 mm) is immersed in water for 5 minutes, and moisture attached to the surface of the obtained prepreg is waste It is the average of the total of 5 points | pieces which calculated | required the mass W2 after wiping off, and remove | divided the water increase amount calculated | required from (W2-W1) by W1, and was expressed in percentage.

  The manufacturing method of the prepreg of this invention is not specifically limited, It can manufacture using a well-known manufacturing method. For example, a wet method in which a thermosetting resin composition is dissolved in a solvent such as methyl ethyl ketone and methanol to lower the viscosity and impregnated, and a hot melt method in which the viscosity is reduced by heating and impregnated (dry method) can be exemplified. . The wet method is a method in which the reinforcing fiber is immersed in a solution of the thermosetting resin composition, and then the solvent is evaporated using a pull-up oven or the like. The hot melt method is a method of directly impregnating a fiber base material composed of reinforcing fibers with a thermosetting resin composition whose viscosity has been reduced by heating. From the reinforcing fibers, the thermosetting resin composition is heated and pressurized. This is a method of impregnating a fiber base material with a resin. The hot melt method is preferable because substantially no solvent remains in the prepreg.

  The method for producing the prepreg of the present invention is not particularly limited, but the pitch of the drawn carbon fibers is passed through the comb and aligned, and the adjacent carbon fibers are alternately passed through the bar, and then the thermosetting resin composition is formed. It is preferable to include an impregnation step. When adjacent carbon fibers alternately pass through the bar, adjacent carbon fibers can be approached from above and below and aligned in one direction. Thereby, the overlap of adjacent carbon fiber can be suppressed and the maximum unevenness | corrugation difference of the prepreg surface can be reduced rather than the method of not letting a bar pass.

  The method for producing a prepreg of the present invention preferably includes a step of opening carbon fibers. By opening the carbon fiber, it is easy to further reduce the maximum unevenness of the prepreg surface.

  The method for producing a prepreg of the present invention preferably includes a step of opening a fiber by passing a roll that vibrates in the width direction of the prepreg. By including this step, it is easy to reduce the maximum unevenness height of the prepreg.

  In the prepreg manufacturing method of the present invention, the frequency of the roll vibrating in the width direction is preferably 5 Hz or less. If it is 5 Hz or less, it is possible to prevent the adjacent carbon fibers from overlapping again, so that it is easy to obtain a unidirectional prepreg in which the maximum unevenness difference is further reduced.

  Hereinafter, the present invention will be described in detail by way of examples. In addition, this invention is not limited to the following Example. The carbon fibers, thermosetting resin compositions, and various measuring methods used in the examples and comparative examples are as follows.

<Carbon fiber>
Carbon fiber ("Torayca (registered trademark)" T700SC-24K, manufactured by Toray Industries, Inc., tensile elastic modulus: 230 GPa, tensile strength: 4900 MPa, fineness: 1.65 g / m, carbon fiber yarn width: 0.008 m).

<Epoxy resin>
-Bisphenol A type liquid epoxy resin ("jER (registered trademark)" 828, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 189).
-Bisphenol A type solid epoxy resin ("jER (registered trademark)" 1001, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 475).
Phenol novolac type epoxy resin (“jER (registered trademark)” 154, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 178).

<Thermoplastic resin>
Polyvinyl formal ("Vinylec (registered trademark)" K, manufactured by jNC Corporation).

<Curing agent>
-Dicyandiamide (DICY7, manufactured by Mitsubishi Chemical Corporation).

<Curing accelerator>
-Toluenebisdimethylurea ("Omicure (R)" 24, manufactured by Emerald Performance Materials, LLC).

<Preparation of thermosetting resin composition>
As epoxy resin, “jER (registered trademark)” 828 is 25.0 mass%, “jER (registered trademark)” 1001 is 40.0 mass%, “jER (registered trademark)” 154 is 30.0 mass%, thermoplasticity “Vinylec (registered trademark)” K as a resin was added in an amount of 2,7% by mass and cooled after being kneaded. Then, 4.0% by mass of DICY7 as a curing agent and “Omicure (registered trademark)” 24 as a curing accelerator. 1.0 mass% was added and kneaded to prepare a thermosetting resin composition.

<Measurement method of prepreg width>
A prepreg width A was determined by measuring the distance between carbon fibers on the outermost sides of the prepreg using a length measuring device such as a measure or a ruler.

<Measurement method of maximum unevenness Rt>
From the prepreg, test pieces having a width of 100 mm and a length of 30 mm were cut out at equal intervals in the direction perpendicular to the prepreg fibers (width direction), and the width was measured at a measurement speed of 2 mm / sec using a contact surface roughness measuring instrument. The needles were moved in the directions, their maximum unevenness difference Rt was measured, and the average value of the average values was defined as the maximum unevenness difference Rt. As a contact type surface roughness measuring instrument, a surface roughness measuring instrument SE-3500 manufactured by Kosaka Laboratory Co., Ltd. was used, and a detector was equipped with a diamond needle having a stylus tip radius of 2 μm and a measuring force of 0.7 mN. What can be measured was used.

<Measurement method of carbon fiber yarn width>
100 cm carbon fibers were placed in a state where no tension was applied, the width of the carbon fibers was measured using a ruler at intervals of 10 cm from one end, and the average length of these was defined as the width B of the carbon fibers.

<Measurement method of FAW variation>
Using five prepregs cut at 100 mm in the width direction and 100 mm in the longitudinal direction as test pieces at equal intervals in the width direction of the prepreg, the thermosetting resin composition is removed from these test pieces with methyl ethyl ketone, and the mass of the carbon fiber is determined. It was measured. From the mass of the obtained carbon fiber, the average value and standard deviation of FAW, FAW, and FAW variation were obtained.

<Measurement method of impregnation rate by water pickup method>
The mass W1 was measured in advance using five prepregs cut at 100 mm in the width direction and 100 mm in the longitudinal direction at equal intervals in the width direction of the prepreg as test pieces. One side of the prepreg is arranged with the fiber direction of the prepreg in the vertical direction, and a range of 5 mm from the end (ie, 100 mm × 5 mm) is immersed in water for 5 minutes. The mass W2 after wiping was obtained, and the water increase obtained from (W2-W1) was divided by W1, and the average value of a total of 5 points expressed as a percentage was taken as the impregnation rate using the water pickup method.

<Surface condition of prepreg>
The prepreg is cut into a square having a length in the width direction and left in an indoor room adjusted to a temperature of 24 ° C. and a humidity of 50% for 1 hour. Thereafter, the floating (brightness) of fibers having a diameter of 3 mm or more on the surface of the prepreg was visually counted, and ◎ indicates that there were less than 1000 pieces of unevenness, and ◎ indicates that there were less than 1000 pieces and less than 3000 pieces. The case where the number of bumps was more than 3000 was marked as x.

<Method for Producing Molded Body and Measuring Method for Thickness Variation>
The prepared prepreg is cut to a size of 300 mm x 300 mm, laminated in one direction so that the thickness of the molded body is 2 mm, and then cured by heating and pressing at 130 ° C and 0.3 MPa for 2 hours in an autoclave. A molded product a was obtained. As shown in FIG. 1, a cross line passing through the center of the formed body was drawn with a pen or the like, and an intersection c of the line b drawn from the cross line to a position of 10 cm toward each side was measured with a micro gauge. Dividing the standard deviation of 9 points by the average value and expressing the percentage as thickness variation, the thickness variation was less than 2.0% and especially excellent ◎, 2.0% or more and less than 4.0% Good and good, and x was 4.0% or more and poor.

<Measurement method of lamination time>
The time taken from the start of work to the end of work is the time taken for the above laminating work, and the thing that was able to be laminated in a short time in less than 10 minutes is a short time in 10 minutes or more but less than 30 minutes ◯, and those requiring 30 minutes or more were marked with ×.

<Example 1>
The prepared thermosetting resin composition was applied onto release paper using a coater to prepare a resin sheet having a resin basis weight of 62.0 g / m ² . Then, "Torayca (registered trademark)" the T700SC-24K was passed through a comb, after aligning the pitch between the carbon fiber, alternately passed through the bar of carbon fibers adjacent to FAW is 250 g / ^{m 2} Were aligned in one direction in a sheet form. Then, the resin sheet was piled up from both surfaces of the carbon fiber, heated and pressurized to impregnate the thermosetting resin composition, and a unidirectional prepreg was produced. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 68 μm, the FAW variation was 1.8%, and the impregnation rate using the water pickup method was 11.4%. Further, the surface state of the prepreg was good, the thickness variation of the molded product was very small, and the lamination time was short.

<Example 2>
A unidirectional prepreg was produced in the same manner as in Example 1 except that the opening portion having a roll in the width direction was passed after passing through the bar. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 63 μm, the FAW variation was 1.4%, and the impregnation rate using the water pickup method was 10.7%. Further, the surface state of the prepreg was good, the thickness variation of the molded product was very small, and the lamination time was short.

<Example 3>
A unidirectional prepreg was produced in the same manner as in Example 2 except that the roll of the opening portion was vibrated at 7 Hz. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 56 μm, the FAW variation was 1.3%, and the impregnation rate using the water pickup method was 8.2%. Further, the surface state of the prepreg was very good, the thickness variation of the molded product was very small, and the lamination time was short.

<Example 4>
A unidirectional prepreg was produced in the same manner as in Example 3 except that the roll of the spread part was vibrated at 5 Hz. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 52 μm, the FAW variation was 1.1%, and the impregnation rate using the water pickup method was 7.6%. Further, the surface state of the prepreg was very good, the thickness variation of the molded product was very small, and the lamination time was short.

<Example 5>
To prepare a unidirectional prepreg except that the the resin sheet resin basis weight 74.0g ^/ m 2, FAW was 300 g / ^{m 2} in the same manner as in Example 1. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 84 μm, the FAW variation was 1.7%, and the impregnation rate using the water pickup method was 10.8%. Further, the surface state of the prepreg was good, the thickness variation of the molded product was very small, and the lamination time was short.

<Example 6>
To prepare a unidirectional prepreg except that the the resin sheet resin basis weight 74.0g ^/ m 2, FAW was 300 g / ^{m 2} in the same manner as in Example 4. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 71 μm, the FAW variation was 1.2%, and the impregnation rate using the water pickup method was 7.4%. Further, the surface state of the prepreg was very good, the thickness variation of the molded product was very small, and the lamination time was short.

<Example 7>
To prepare a unidirectional prepreg except that the the resin sheet resin basis weight 87.0g ^/ m 2, FAW was 350 g / ^{m 2} in the same manner as in Example 1. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 107 μm, the FAW variation was 1.9%, and the impregnation rate using the water pickup method was 12.2%. Further, the surface state of the prepreg was good, the thickness variation of the molded product was small, and the lamination time was very short.

<Example 8>
To prepare a unidirectional prepreg except that the the resin sheet resin basis weight 87.0g ^/ m 2, FAW was 350 g / ^{m 2} in the same manner as in Example 4. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 98 μm, the FAW variation was 1.2%, and the impregnation rate using the water pickup method was 7.8%. Further, the surface state of the prepreg was very good, the thickness variation of the molded product was very small, and the lamination time was very short.

<Example 9>
To prepare a unidirectional prepreg except that the the resin sheet resin basis weight 99.0g ^/ m 2, FAW was 400 g / ^{m 2} in the same manner as in Example 1. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 126 μm, the FAW variation was 1.9%, and the impregnation rate using the water pickup method was 13.2%. Further, the surface state of the prepreg was good, the thickness variation of the molded product was small, and the lamination time was very short.

<Example 10>
A unidirectional prepreg was produced in the same manner as in Example 9 except that the opening portion having a roll in the width direction was passed after passing through the bar. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 121 μm, the FAW variation was 1.4%, and the impregnation rate using the water pickup method was 12.5%. Further, the surface state of the prepreg was good, the thickness variation of the molded product was small, and the lamination time was very short.

<Example 11>
A unidirectional prepreg was produced in the same manner as in Example 10 except that the roll of the opening portion was vibrated at 7 Hz. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 113 μm, the FAW variation was 1.2%, and the impregnation rate using the water pickup method was 8.9%. Further, the surface state of the prepreg was very good, the thickness variation of the molded product was small, and the lamination time was very short.

<Example 12>
A unidirectional prepreg was produced in the same manner as in Example 11 except that the roll of the spread part was vibrated at 5 Hz. This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 111 μm, the FAW variation was 1.2%, and the impregnation rate using the water pickup method was 7.5%. Further, the surface state of the prepreg was very good, the thickness variation of the molded product was very small, and the lamination time was very short.

<Comparative Example 1>
A unidirectional prepreg was prepared in the same manner as in Example 4 except that adjacent carbon fibers were alternately passed through the bar before passing the comb and aligning the pitch between the carbon fibers. This prepreg satisfies the formula (1), but does not satisfy the formula (2). The maximum unevenness difference Rt is 81 μm, the FAW variation is 3.7%, and the impregnation rate using the water pickup method is 7.3%. there were. Further, the surface state of the prepreg was very good, the thickness variation of the molded body was very large, and the lamination time was short.

<Comparative example 2>
A unidirectional prepreg was produced in the same manner as in Example 4, except that the carbon fiber used had a yarn width of 0.004 m and the opening roll was vibrated at 20 Hz. Although this prepreg does not satisfy the formula (1), it satisfies the formula (2), the maximum unevenness difference Rt is 67 μm, the FAW variation is 2.8%, and the impregnation rate using the water pickup method is 5.5%. Met. Further, the surface state of the prepreg was very good, the thickness variation of the molded body was very large, and the lamination time was short.

<Comparative Example 3>
A unidirectional prepreg was produced in the same manner as in Example 4 except that the carbon fiber used had a yarn width of 0.016 m. Although this prepreg does not satisfy the formula (1), the formula (2) is satisfied, the maximum unevenness difference Rt is 68 μm, the FAW variation is 2.5%, and the impregnation rate using the water pickup method is 8.1%. Met. Further, the surface state of the prepreg was very good, the thickness variation of the molded body was very large, and the lamination time was short.

<Comparative example 4>
A unidirectional prepreg was prepared in the same manner as in Example 4 except that the resin basis weight of the resin sheet was 37.0 g / m ² , the carbon fiber used had a yarn width of 0.016 m, and FAW was 150 g / m ² . This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 27 μm, the FAW variation was 2.2%, and the impregnation rate using the water pickup method was 1.3%. Further, the surface condition of the prepreg was very good, the thickness variation of the molded product was very small, and it took time for the lamination time.

<Comparative Example 5>
A unidirectional prepreg was produced in the same manner as in Example 4 except that the resin basis weight of the resin sheet was 124.0 g / m ² , the yarn width of the carbon fiber used was 0.004 m, and FAW was 500 g / m ² . This prepreg satisfied the formulas (1) and (2), the maximum unevenness difference Rt was 159 μm, the FAW variation was 2.4%, and the impregnation rate using the water pickup method was 15.9%. Further, the surface state of the prepreg was very bad, the thickness variation of the molded product was very large, and the lamination time was very short.

  The prepreg of the present invention can be preferably used in applications where accuracy and rigidity are required because a laminated plate in which thickness variation of the laminated plate is suppressed can be laminated in a shorter time.

a: Molded body b: Line c: Measurement location

Claims (7)

A prepreg formed by impregnating a thermosetting resin composition with carbon fibers aligned in one direction, and a fiber basis weight (FAW (g / m ² )) per unit area of the prepreg is 250 to 400 g / m ² , the prepreg width is A (m), the maximum unevenness of the prepreg surface is Rt (μm), the carbon fiber thread width is B (m), and the fiber basis weight per unit length of the carbon fiber is C ( g / m), a prepreg that simultaneously satisfies the following equations (1) and (2):
2A ≧ (FAW / C) × B ≧ A (1)
Rt ≦ 70 + 0.4 (FAW−250) (2) The prepreg according to claim 1, wherein FAW variation (CV value) in the width direction of the prepreg is 1.5% or less. The prepreg according to claim 1 or 2, wherein the impregnation ratio measured using a water pickup method is 10.0% or less. It is a manufacturing method of the prepreg which manufactures the prepreg in any one of Claims 1-3, Comprising: The pitch between carbon fibers is arrange | equalized with a comb, After passing adjacent carbon fiber alternately to a bar, it is thermosetting. A method for producing a prepreg impregnated in a resin composition. The method for producing a prepreg according to claim 4, wherein the carbon fiber after passing through the bar is further opened. The method for producing a prepreg according to claim 5, wherein the fiber is opened by passing through a roll that vibrates in the width direction. The method for producing a prepreg according to claim 6, wherein the roll has a frequency of 5 Hz or less.

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