JP2009197359A - Reinforcing fiber, and fiber-reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcing fiber having excellent adhesiveness to reinforcing fiber, good handleability, and fiber dispersibility in injection molding. <P>SOLUTION: Provided are a reinforcing fiber produced by applying 0.01-30 pts.wt. of copolymers (B) composed of (a) 10-50 wt.% aromatic vinyl monomer units, (b) 50-90 wt.% (meth)acrylate monomer units, and (c) 0-30 wt.% other vinyl monomer copolymerizable with the units (a) and (b) to 100 pts.wt. of reinforcing fibers (A), and a fiber-reinforced composite material composed of the reinforcing fiber and a matrix resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  An object of this invention is to provide the reinforced fiber which is excellent in the adhesiveness with a matrix resin, the handleability, and the fiber dispersibility at the time of injection molding. In particular, it is an object of the present invention to provide a reinforcing fiber having excellent adhesion and handling property and good fiber dispersibility at the time of injection molding in a fiber reinforced composite material composed of carbon fiber and thermoplastic resin.

  Fiber-reinforced resin molded products in which reinforcing fibers are dispersed in a matrix resin are used in a wide range of fields such as automobiles, aircraft, electrical / electronic devices, toys, and home appliances because of their excellent mechanical properties and dimensional stability. . Among them, carbon fiber has attracted attention in recent years because it is lightweight, high strength, and high rigidity.

  However, the reinforcing fiber with few functional groups and the fiber reinforced composite material molded product using the matrix resin have insufficient interface adhesion between the reinforcing fiber and the matrix resin, and the mechanical properties of the molded product are not satisfactory. . Therefore, attempts have been made to improve the handleability and interfacial adhesion of the reinforcing fibers, such as surface treatment and application of a sizing agent.

  Patent Document 1 discloses a sizing agent made of an epoxy resin as a sizing agent for carbon fiber, which has sufficient convergence but is bonded to a matrix resin when a thermoplastic resin is used as the matrix resin. Is insufficient. Patent Document 2 discloses a carbon fiber to which an ionomer resin is attached in an amount of 0.1 to 8% by weight. Similarly, Patent Document 3 describes a carbon fiber having 0.1 to 8% by weight of a self-emulsifying polypropylene resin attached to the carbon fiber. Both patent documents aim to prevent impregnation of the matrix resin into the carbon fibers, and the adhesion is improved and the carbon fibers are not sufficiently dispersed during injection molding.

As described above, it is difficult for the conventional technology to achieve both excellent adhesiveness and handleability, and further, dispersibility of the reinforcing fiber at the time of injection molding, and the development of a reinforcing fiber that satisfies these characteristics has been desired. .
JP-A-5-132874 JP 2006-124852 A JP 2006-233346 A

  In view of the background of the prior art, an object of the present invention is to provide a reinforcing fiber that is excellent in adhesiveness with a reinforcing fiber, has good handleability, and excellent fiber dispersibility during injection molding.

  As a result of intensive studies to achieve the above object, the present inventors have found the following reinforcing fiber that can achieve the above-mentioned problems.

  (1) 100 parts by weight of the reinforcing fiber (A), (a) 10 to 50% by weight of an aromatic vinyl monomer unit, (b) 50 to 90% by weight of a (meth) acrylate monomer unit, (C) Reinforcing fiber comprising 0.01 to 30 parts by weight of a copolymer (B) comprising 0 to 30% by weight of another vinyl monomer unit copolymerizable with (a) and (b) .

  (2) The reinforcing fiber according to (1), wherein the component (B) is modified with an amino group.

  (3) The reinforcing fiber according to (2), wherein the component (b) is a vinyl monomer containing an amino group at an ester terminal.

  (4) The reinforcing fiber according to any one of (2) and (3), wherein the amino group of the component (B) is a tertiary amine and / or a quaternary ammonium salt.

  (5) The reinforcing fiber according to any one of (2) to (4), wherein the amine value of the component (B) is 1 to 100 mg eq / g.

  (6) The reinforcing fiber according to any one of (1) to (5), wherein the glass transition temperature of the component (B) is 30 to 100 ° C.

  (7) The reinforcing fiber according to any one of (1) to (6), wherein the component (B) has a weight average molecular weight of 1,000 to 500,000.

  (8) The monomer (b) has at least one selected from ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and octyl (meth) acrylate, The reinforcing fiber according to any one of (7).

  (9) The reinforcing fiber according to any one of (1) to (8), wherein the component (A) is at least one selected from carbon fiber, aramid fiber, and mineral fiber.

  (10) The carbon fiber according to (9), wherein the carbon fiber has a surface oxygen concentration ratio measured by X-ray photoelectron spectroscopy of 0.05 to 0.5.

  (11) The reinforcing fiber according to any one of (1) to (10), wherein the reinforcing fiber is a reinforcing fiber formed by bundling 10,000 to 200,000 single fibers.

  (12) A fiber-reinforced composite material comprising the reinforcing fibers according to (1) to (11) and a matrix resin.

  (13) The fiber-reinforced composite material according to (12), wherein the matrix resin is at least one thermoplastic resin selected from olefins, amides, and esters.

  By using a specific copolymer, the reinforcing fiber of the present invention is a reinforcing fiber that is excellent in adhesiveness and handling with the reinforcing fiber and has good fiber dispersibility during injection molding. Since the molded article using the reinforcing fiber of the present invention is excellent in mechanical properties and dimensional stability, it is extremely useful for various parts and members such as automobiles, electrical / electronic devices, and home appliances.

  The present invention relates to 100 parts by weight of the reinforcing fiber (A), (a) 10 to 50% by weight of an aromatic vinyl monomer unit, and (b) 50 to 90% by weight of a (meth) acrylic acid ester monomer unit. (C) Reinforcement formed by adhering 0.1 to 30 parts by weight of copolymer (B) consisting of 0 to 30% by weight of other vinyl monomer units copolymerizable with (a) and (b) Fiber.

  As the reinforcing fiber according to the present invention, for example, high-strength and high-modulus fibers such as carbon fiber, mineral fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, and metal fiber can be used. Two or more kinds may be used in combination. Among these, PAN-based, pitch-based and rayon-based carbon fibers are preferable from the viewpoint of improving the mechanical properties and reducing the weight of the molded product, and from the viewpoint of the balance between the strength and elastic modulus of the molded product obtained. Fiber is more preferred. For the purpose of imparting conductivity, reinforcing fibers coated with a metal such as nickel, copper, or ytterbium can also be used.

  Further, as the carbon fiber, the surface oxygen concentration ratio [O / C], which is the ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface measured by X-ray photoelectron spectroscopy, is 0.05-0. 5 is preferable, more preferably 0.08 to 0.4, and still more preferably 0.1 to 0.3. When the surface oxygen concentration ratio is 0.05 or more, the functional group amount on the surface of the carbon fiber can be secured, and a stronger adhesion to the thermoplastic resin can be obtained. Moreover, although there is no restriction | limiting in particular in the upper limit of surface oxygen concentration ratio, Generally it can be illustrated to 0.5 or less from the balance of the handleability of carbon fiber, and productivity.

The surface oxygen concentration ratio of the carbon fiber is determined by X-ray photoelectron spectroscopy according to the following procedure. First, carbon fibers from which the sizing agent and the like adhering to the carbon fiber surface were removed with a solvent were cut to 20 mm, spread on a copper sample support base, and then arranged using an A1Kα1,2 as an X-ray source. Keep 1 × 10 ⁸ Torr in the chamber. The kinetic energy value (KE) of the main peak of C _1s is adjusted to 1202 eV as a peak correction value associated with charging during measurement. C _1s peak area E. Is obtained by drawing a straight base line in the range of 1191 to 1205 eV. O _1s peak area E. Is obtained by drawing a straight base line in the range of 947 to 959 eV.

Here, the surface oxygen concentration ratio is calculated as an atomic number ratio from the ratio of the O _1s peak area to the C _1s peak area using a sensitivity correction value unique to the apparatus. As an X-ray photoelectron spectroscopy apparatus, model ES-200 manufactured by Kokusai Electric Inc. is used, and the sensitivity correction value is set to 1.74.

  The means for controlling the surface oxygen concentration ratio [O / C] to 0.05 to 0.5 is not particularly limited. For example, techniques such as electrolytic oxidation, chemical oxidation, and vapor phase oxidation are used. Among these, electrolytic oxidation treatment is preferable.

  The average fiber diameter of the reinforcing fibers is not particularly limited, but is preferably in the range of 1 to 20 μm and in the range of 3 to 15 μm from the viewpoint of mechanical properties and surface appearance of the obtained molded product. More preferred. There is no restriction | limiting in particular in the number of single yarns of a reinforced fiber, It can use within the range of 100-350,000, Especially within the range of 1,000-250,000, More preferably, it is 10,000-200. From the viewpoint of handleability, it is preferable to use within the range of 1,000.

  Here, (a) the aromatic vinyl monomer is not particularly limited as long as it is an aromatic vinyl monomer, but styrene, α-methylstyrene, 2-methylstyrene, 3- Methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, 3,4-dimethylstyrene, 4-methoxystyrene, 4-ethoxystyrene, 4-hydroxymethylstyrene, 2-chlorostyrene, 3- Examples include chlorostyrene, 4-chlorostyrene, 4-chloro-3-methylstyrene, 2,4-dichlorosrene, 2,6-dichlorostyrene, 1-vinylnaphthalene and the like. You may use each individually or in mixture of 2 or more types.

  Examples of (b) (meth) acrylic acid ester monomers include alkyl (meth) acrylates, hydroxyl group-containing (meth) acrylates, fluorine-containing (meth) acrylates, amino group-containing (meth) acrylates, and the like.

  Examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, and i-butyl. (Meth) acrylate, t-butyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) ) Acrylate, cyclohexyl (meth) acrylate, and the like. Examples of hydroxyl group-containing (meth) acrylates include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, diethylene glycol mono (meth) acrylate, and polyethylene glycol mono (Meth) acrylate, dipropylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate and the like. Examples of fluorine-containing (meth) acrylates include 2,2,2-trifluoroethyl (meth) acrylate, 8,8,8,7,7-pentafluoro-n-octyl (meth) acrylate, and the like. Can do. Examples of amino group-containing (meth) acrylates include aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, 2-aminoethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, 2- ( and n-butylamino) ethyl (meth) acrylate. Examples of (meth) acrylates other than (meth) acrylates include benzyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2-alkylphenoxy) ethyl (meth) acrylate, and phenoxydiethylene glycol (meth) acrylate. Of phenoxypolyethylene glycol (meth) acrylate, phenoxypropylene glycol (meth) acrylate, phenoxydipropylene glycol (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, phthalic acid And mono (ethylene glycol mono (meth) acrylate) / 2-hydroxyethyl mixed ester. You may use each individually or in mixture of 2 or more types.

  (C) Other vinyl monomers copolymerizable with (a) and (b) are not particularly limited, but include unsaturated amide compounds, vinyl cyanide compounds, unsaturated epoxy compounds, vinyls. Examples include ester compounds, carbonyl group-containing unsaturated compounds, unsaturated carboxylate compounds, and unsaturated sulfonate compounds. Examples of the unsaturated amide compound include acrylamide, N-methylaminoacrylamide, N, N-dimethylaminoacrylamide, N, N-dimethylaminoacrylamidomethyl chloride quaternary salt, N, N-dimethylaminopropylacrylamide methyl chloride 4 Examples include grade salts and N-methylaminopropyl acrylamide. Examples of the vinyl cyanide compound include acrylonitrile, α-chloroacrylonitrile, vinylidene cyanide and the like. Examples of the vinyl halide compound include vinyl fluoride, vinyl chloride, and vinylidene chloride. Examples of vinyl esters include vinyl acetate and fatty acid vinyl esters. Examples of the unsaturated epoxy compound include allyl glycidyl ether, glycidyl acrylate, methyl glycidyl acrylate, and the like. Examples of the carbonyl group-containing unsaturated compound include acrolein, diacetone acrylamide, 2-acetoxyethyl acrylate, caprolactone-modified acetoxy acrylate, and the like. You may use each individually or in mixture of 2 or more types.

  The content of (a) in the copolymer (B) of the present invention needs to be 10 to 50% by weight, and more preferably 20 to 40% by weight. If it is 10% by weight or less, the glass transition temperature of the copolymer is lowered, and the copolymer becomes a flexible copolymer at room temperature. On the other hand, if it is 50% by weight or more, the adhesiveness with the reinforcing fiber surface is lowered, and the mechanical properties may be insufficient.

  The content of (b) in the copolymer (B) of the present invention needs to be 50 to 90% by weight, and more preferably 60 to 80% by weight. If it is 50% by weight or less, the adhesion to the surface of the reinforcing fiber is lowered and the mechanical properties become insufficient. On the other hand, if it is 90% by weight or more, the adhesion to the surface of the reinforcing fiber is sufficient, but the glass transition temperature of the copolymer is lowered and the copolymer becomes a flexible copolymer at room temperature. There is a case.

  The content of (c) in the copolymer (B) of the present invention needs to be 0 to 30% by weight, and more preferably 0 to 20% by weight. If it is 30% by weight or more, it is difficult to achieve both handleability and adhesion of the reinforcing fiber, which is not preferable. On the other hand, the content of (c) in the copolymer (B) of the present invention is 0% by weight, that is, the copolymer (B) consists essentially of (a) and (b). But there is no problem.

  By adhering the copolymer (B) to the reinforcing fibers, it is possible to improve the convergence when handling the reinforcing fibers and to suppress the generation of fluff due to rubbing. Furthermore, when melt-kneading with the matrix resin, the adhesion between the matrix resin and the reinforcing fibers can be improved, and the reinforcing fibers can be easily dispersed in the matrix resin.

  Moreover, it is 0.01-30 weight part with respect to the adhesion amount to the reinforced fiber of a copolymer, ie, 100 weight part of reinforced fiber of a copolymer. More preferably, it is 0.05-25 weight part, More preferably, it is 0.1-10 weight part. When the amount is less than 0.01 part by weight, the reinforcing fiber cannot be adhered to the whole and sufficient mechanical properties cannot be obtained in the obtained molded product. On the other hand, when the adhesion amount exceeds 30 parts by weight, the mechanical properties of the molded product may be deteriorated.

Here, the adhesion amount measurement is not particularly limited, but about 5 g of the reinforcing fiber is taken, dried at 120 ° C. for 3 hours, the weight is set to W ₁ (g), and then the reinforcing fiber is 15% at 450 ° C. in a nitrogen atmosphere. The amount of adhesion was calculated by the following equation using the weight W ₂ (g) cooled to room temperature after heating for minutes.

Adhering amount = [(W ₁ −W ₂ ) / W ₁ ] × 100 / W ₁ (parts by weight).

  The copolymer (B) of the present invention is particularly preferably modified with an amino group. By modifying the amino group, it is possible to improve the adhesion with the reinforcing fiber while maintaining the handleability. The amino group modification method is not particularly limited, but the amino compound of the copolymer (B) may be modified, or an amino group modification monomer may be used as a monomer constituting the copolymer (B). It may be used.

The method for modifying the amine compound is not particularly limited, but is a melt kneader such as a single-screw extruder, a co-rotating twin-screw extruder, a counter-rotating twin-screw extruder, a heating roll, a Banbury mixer, a brabender, and various kneaders. Can be used to knead and produce the copolymer (B) and the amine modifier. Although it does not specifically limit as an amine modifier, The allylamine which has a primary or secondary amine is preferable.
As a method of using an amino group-modified monomer as a monomer, an amino group-modified monomer may be used for any of the components (a), (b), and (c). For b), it is preferable to use a vinyl-based monomer containing an amino group at the ester terminal in order to improve adhesiveness while maintaining fiber dispersibility during injection molding.

  The amine value of the copolymer (B) in the present invention is preferably 1 to 100 mg eq / g, more preferably 10 to 80 mg eq / g. Adhesiveness is improved, maintaining a handleability and the fiber dispersibility at the time of injection molding as it is 1-100 mg eq / g.

  Here, the amine value is an index showing the total number of 1,2,3 amines measured according to ASTM D2074, and is expressed in mg of KOH equivalent to hydrochloric acid to neutralize 1 g of component.

  In the copolymer (B) of the present invention, the glass transition temperature of the copolymer (B) is preferably 30 to 100 ° C., more preferably 40 to 90 ° C., from the viewpoint of the handleability of the reinforcing fibers. is there. When the glass transition temperature of the copolymer (B) is from 30 ° C. to 100 ° C., the handleability is good and the balance between fiber dispersibility and mechanical properties during injection molding is good.

  From the viewpoint of the mechanical properties of the resulting molded article, the copolymer (B) preferably has a weight average molecular weight of 1,000 to 500,000, more preferably 10,000 to 400. , 000. By setting the weight average molecular weight within the above range, it is preferable for maintaining good mechanical properties of the molded product. In addition, the measurement of a weight average molecular weight is obtained from measuring using a general well-known gel permeation chromatography (GPC).

  Identification of the monomer repeating unit in the copolymer (B) can be carried out by using ordinary polymer compound analysis techniques such as IR, NMR, mass spectrometry and elemental analysis.

  Here, (b) in the copolymer (B) of the present invention is at least one selected from ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and octyl (meth) acrylate. It is preferable to use it because of the good balance between the adhesiveness and the fluidity of the reinforcing fiber during molding. In addition, you may use each individually or in mixture of 2 or more types.

  The method for adhering to the reinforcing fibers is not particularly limited, but from the viewpoint of easily adhering between the single fibers, a method of drying after applying the solution or emulsion of the copolymer to the reinforcing fibers is preferable. As a method of applying an emulsion to the reinforcing fiber, a method of applying by an existing method such as a roller dipping method, a roller transfer method, or a spray method can be used.

  In addition to the copolymer (B), other components may be attached to the reinforcing fiber of the present invention as long as the effects of the present invention are not impaired. For example, when the copolymer (B) is applied to the reinforcing fiber in the form of an emulsion, a surfactant or the like for stabilizing the emulsion may be added separately.

  As a preferable shape of the reinforcing fiber in the present invention, there are a roving which is a continuous fiber, a chopped yarn obtained by cutting the roving into a predetermined length, and a pulverized milled yarn. Although the fiber length in the chopped yarn is not particularly limited, it is 1 to 30 mm because the supply property to the extruder is good while fully converging and maintaining the shape after being cut sufficiently. The range of 2-15 mm is more preferable.

  The matrix resin constituting the molding material is not particularly limited, and may be either a thermosetting resin or a thermoplastic resin. For example, epoxy resin, urethane resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin and other heat-effective resins, polycarbonate resin, styrene resin, polyamide resin, polyester resin, polyphenylene sulfide resin (PPS resin), modified Acrylic resins such as polyphenylene ether resin (modified PPE resin), polyacetal resin (POM resin), liquid crystal polyester, polyarylate, polymethyl methacrylate resin (PMMA), vinyl chloride, polyimide (PI), polyamideimide (PAI), poly Polyethers such as etherimide (PEI), polysulfone, polyethersulfone, polyketone, polyetherketone, polyetheretherketone (PEEK) polyethylene, polypropylene, modified poly Thermoplastic resins such as olefin, phenol resin, phenoxy resin, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / propylene / diene copolymer, ethylene / carbon monoxide / diene copolymer , Ethylene / ethyl (meth) acrylate copolymer, ethylene / glycidyl (meth) acrylate, ethylene / vinyl acetate / glycidyl (meth) acrylate copolymer, polyether ester elastomer, polyether ether elastomer, polyether ester Various elastomers such as an amide elastomer, a polyesteramide elastomer, and a polyester ester elastomer may be used, and one or more of these may be used in combination. From the viewpoint of recyclability, a thermoplastic resin is preferable, and polyolefin-based, polyamide-based, and polyester-based resins that are particularly versatile are preferable. Among these, from the viewpoints of cost and lightness of molded products, polyolefin resins are preferable, and polypropylene or modified polypropylene resins, particularly acid-modified polypropylene resins are more preferable.

  The molded product obtained by the present invention can be developed for various uses by taking advantage of excellent mechanical properties. Especially automotive parts such as instrument panel, door beam, under cover, lamp housing, pedal housing, radiator support, spare tire cover, various modules such as front end, notebook computer, mobile phone, digital still camera, PDA, plasma display, etc. Suitable for household and office electrical product parts such as electric / electronic parts, telephones, facsimiles, VTRs, copiers, televisions, microwave ovens, audio equipment, toiletries, laser discs, refrigerators, air conditioners.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(1) Weight average molecular weight measurement of copolymer (B) It measured with the gel permeation chromatography (GPC). A GPC column packed with polystyrene cross-linked gel was used. Measurement was performed at 150 ° C. using 1,2,4-trichlorobenzene as a solvent. The molecular weight was calculated in terms of standard polystyrene.

(2) Bending characteristic evaluation According to the standard of ASTM D-790, using a three-point bending test jig (indenter 10 mm, fulcrum 10 mm), the support span is set to 100 mm, and the bending strength is measured at a crosshead speed of 5.3 mm / min. did. As a testing machine, “Instron” (registered trademark) universal testing machine 4201 type (manufactured by Instron) was used. The number of measurements was n = 5, and the average values were the bending strength and bending elastic modulus. The bending characteristics were determined under the conditions that the moisture content of the test piece was 0.1% or less, the ambient temperature was 23 ° C., and the humidity was 50 wt%.

(3) Izod Impact Characteristic Evaluation A notched Izod impact test was conducted according to ASTM D256 standard. The notched Izod impact strength (J / m) was determined under conditions of a moisture content of 0.1% or less, an ambient temperature of 23 ° C., and a humidity of 50% by weight. The number of measurements was 8 times, and the average was taken as the Izod impact strength.

(4) Evaluation of handling properties of reinforcing fibers When pulling out the reinforcing fibers through three stainless steel drums arranged in a zigzag manner at a speed of 30 m / min, no fluff is observed or several When the fluff was observed, it was marked as ◯ (good handleability), and when there was a lot of fluff and significant single yarn breakage was observed, it was marked as x (poor handleability).

  The materials used in the examples are shown as reference examples below.

Reference Example 1 Reinforcing fiber Spinning, firing treatment, and surface oxidation treatment were carried out from a copolymer containing polyacrylonitrile as a main component to obtain continuous carbon fibers having a total number of 12,000 single yarns. The characteristics of this continuous carbon fiber were as follows.

Single fiber diameter: 7μm
Mass per unit length: 0.8 g / m
Specific gravity: 1.8
Surface oxygen concentration ratio [O / C]: 0.06
Tensile strength: 4600 MPa
Tensile modulus: 220 GPa.
Here, the surface oxygen concentration ratio was determined according to the following procedure by X-ray photoelectron spectroscopy using the carbon fiber after the surface oxidation treatment. First, the carbon fibers were cut to 20 mm, spread and arranged on a copper sample support, and then A1Kα1,2 was used as an X-ray source, and the inside of the sample chamber was kept at 1 × 10 ⁸ Torr. The kinetic energy value (KE) of the main peak of C _1s was adjusted to 1202 eV as a peak correction value associated with charging during measurement. C _1s peak area E. As a linear base line in the range of 1191 to 1205 eV. O _1s peak area E. As a linear base line in the range of 947 to 959 eV. The atomic ratio was calculated from the ratio of the O _1s peak area to the C _1s peak area using the sensitivity correction value unique to the apparatus. As an X-ray photoelectron spectroscopy apparatus, Kokusai Denki Co., Ltd. model ES-200 was used, and the sensitivity correction value was set to 1.74.

Reference Example 2 Copolymer (A-1) Emulsion While stirring, 1 part by weight of sodium lauryl sulfate was added to 150 parts by weight of ion-exchanged water in a glass reaction vessel, and the temperature in the reaction vessel was raised to 65 ° C.

  A monomer mixture comprising 40 parts by weight of styrene, 30 parts by weight of n-butyl acrylate, 20 parts by weight of N, N-dimethylaminoethyl acrylate, and 10 parts by weight of N, N-dimethylaminopropylacrylamide methyl chloride quaternary salt. The liquid was adjusted. A part of this monomer mixture was added before the start of the polymerization initiator. After sufficiently stirring in the reaction vessel, a potassium oleate aqueous solution of cumene hydroperoxide was continuously added dropwise over 3 hours to complete the polymerization. Moreover, the remaining brief mixed liquid was continuously dripped over 2 hours from the start of addition of an initiator, and the copolymer (A-1) emulsion was obtained. The polymerization conversion rate at this time was 98% or more, and almost no solidified product was observed during the polymerization. The emulsion was passed through a 100 mesh wire mesh and no residue was observed.

Weight average molecular weight 100,000
Solid content 40% by weight
Reference Example 3. Copolymer (A-2) Emulsion Copolymer (A-2) emulsion was prepared in the same manner as in Reference Example 2 except that 20 parts by weight of styrene and 80 parts by weight of n-butyl acrylate were used as monomers. Obtained.

Weight average molecular weight 400,000
Solid content 40% by weight
Reference Example 4 Adhesive compound (B-1)
The adhering compound (B-1) is 50 parts by weight of a bisphenol type epoxy resin (“EP8007” (registered trademark), manufactured by Yuka Shell Co., Ltd., average molecular weight 2900), “bisphenol type epoxy resin (manufactured by Yuka Shell Co., Ltd.)” EP834 "(registered trademark), average molecular weight 380) 50 parts by weight and 1,3-phenylenebis-2-oxazoline 5 parts by weight were mixed and diluted to 10% by weight with methyl ethyl ketone.

Reference Example 5 Adhesive compound (B-2)
As the adhesion compound (B-2), polystyrene (“G120K” (registered trademark) manufactured by Nippon Polystyrene Co., Ltd.) was diluted to 10% by weight with methyl ethyl ketone.

Reference Example 6 Adhesive compound (B-3)
As the adhesion compound (B-3), polymethyl methacrylate (“560F” (registered trademark) manufactured by Asahi Kasei Chemicals Corporation) was diluted to 10% by weight with methyl ethyl ketone.

Example 1.
The continuous carbon fiber obtained in Reference Example 1 was immersed in the copolymer emulsion (A-1) prepared in Reference Example 2 in a solid content concentration of 40% by weight and dried at 150 ° C. for 30 minutes to remove moisture. . The continuous carbon fibers were cut into 6 mm long chopped carbon fibers using a cartridge cutter, to obtain chopped carbon fibers having 10% by weight of copolymer (A-1) attached thereto.

  31 parts by weight of the chopped carbon fiber obtained (copolymer (A-1) is 1 part by weight, set so that the content of carbon fiber alone is 30 parts by weight) and unmodified polypropylene resin (Nippon Polypropylene) 39 parts by weight of pellets of “NOBAK PP” MA3 (registered trademark) manufactured by Co., Ltd. and 30 parts by weight of pellets of acid-modified polypropylene resin (“Admer” QE800 (registered trademark) manufactured by Mitsui Chemicals, Inc.) Using a mold mixer, mixing was performed for 120 seconds at a charge of 5 kg and a rotation of 30 rpm to obtain a molding material.

  A test piece for property evaluation was molded from the obtained molding material at a cylinder temperature of 230 ° C. and a mold temperature of 60 ° C. using a J350 ELIII type injection molding machine manufactured by Nippon Steel Works. The nozzle, screw, and cylinder of the injection molding machine were of general-purpose specifications, the molding conditions were a back pressure of 0.3 MPa, the screw rotation speed was 25 rpm, and the lightweight time was within 20 seconds. The characteristic evaluation results are collectively shown in Table 1.

Example 2
An injection molded article was prepared in the same manner as in Example 1 except that the amount of the copolymer emulsion (A-2) prepared in Reference Example 2 was 3 parts by weight. The characteristic evaluation results are collectively shown in Table 1.

Comparative Example 1
An injection-molded product was prepared in the same manner as in Example 1 except that the continuous carbon fiber obtained in Reference Example 1 was used as it was to create a chopped carbon fiber. The characteristic evaluation results are collectively shown in Table 1.

Comparative Example 2
An injection molded product was prepared in the same manner as in Example 1 except that the epoxy described in Reference Example 4 was used and the amount of adhesion to the carbon fiber was 3 parts by weight. The characteristic evaluation results are collectively shown in Table 1.

Comparative Example 3
An injection molded product was prepared in the same manner as in Example 1 except that the polystyrene described in Reference Example 5 was used and the amount of adhesion to carbon fiber was 3 parts by weight. The characteristic evaluation results are collectively shown in Table 1.

Comparative Example 4
An injection molded product was prepared in the same manner as in Example 1 except that the polymethyl methacrylate described in Reference Example 6 was used and the amount of adhesion to carbon fiber was 10 parts by weight. The characteristic evaluation results are collectively shown in Table 1.
In Table 1, the adhesion amount of the component (B) represents the adhesion amount [parts by weight] of the component (B) with respect to 100 parts by weight of the component (A).

  As described above, in Examples 1 and 2, the reinforcing fiber was excellent in handleability, had good fiber dispersibility when formed into an injection molded product, and was able to obtain a molded product having excellent mechanical properties.

  On the other hand, in Comparative Example 1, nothing was adhered to the carbon fiber, a lot of fluff was generated, the handleability was extremely poor, and molding was impossible. In Comparative Example 2, the handleability and fiber dispersibility of the reinforcing fibers were good, but the mechanical properties were inferior.

Claims (13)

Reinforcing fiber (A) 100 parts by weight, (a) 10-50 wt% aromatic vinyl monomer units, (b) 50-90 wt% (meth) acrylate monomer units, (c) Reinforcing fiber comprising 0.01 to 30 parts by weight of a copolymer (B) comprising 0 to 30% by weight of another vinyl monomer unit copolymerizable with (a) and (b). The reinforcing fiber according to claim 1, wherein the component (B) is modified with an amino group. The reinforcing fiber according to claim 2, wherein the component (b) is a vinyl monomer containing an amino group at an ester terminal. The reinforcing fiber according to any one of claims 2 and 3, wherein the amino group of the component (B) is a tertiary amine and / or a quaternary ammonium salt. The reinforcing fiber according to any one of claims 2 to 4, wherein the component (B) has an amine value of 1 to 100 mg eq / g. The reinforcing fiber according to any one of claims 1 to 5, wherein the component (B) has a glass transition temperature of 30 to 100C. The reinforcing fiber according to any one of claims 1 to 6, wherein the component (B) has a weight average molecular weight of 1,000 to 500,000. The monomer (b) has at least one selected from ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and octyl (meth) acrylate, any one of claims 1-7 The reinforcing fiber according to crab. The reinforcing fiber according to any one of claims 1 to 8, wherein the component (A) is at least one selected from carbon fiber, aramid fiber, and mineral fiber. The carbon fiber according to claim 9, wherein the carbon fiber has a surface oxygen concentration ratio measured by X-ray photoelectron spectroscopy of 0.05 to 0.5. The reinforcing fiber according to any one of claims 1 to 10, wherein the reinforcing fiber is a reinforcing fiber formed by bundling 10,000 to 200,000 single fibers. A fiber-reinforced composite material comprising the reinforcing fiber according to claim 1 and a matrix resin. The fiber-reinforced composite material according to claim 12, wherein the matrix resin is at least one thermoplastic resin selected from olefin-based, amide-based, and ester-based resins.