JP2017133131A - Recycled carbon short fiber nonwoven fabric, and composite body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycled carbon short fiber nonwoven fabric in which the dispersibility of a recycled carbon short fiber does not deteriorate and the processability is excellent when subjecting to heating or heating and compressing treatment in a production process of a recycled carbon fiber reinforced thermoplastic resin composite body, and when subjecting to heat press processing in a production process of a molded article from the recycled carbon fiber reinforced thermoplastic resin composite body, and a composite body obtained by laminating the recycled carbon short fiber nonwoven fabric and a thermoplastic resin film.SOLUTION: The recycled carbon short fiber nonwoven fabric includes a recycled carbon short fiber, a thermoplastic resin fiber, and a fibrillated cellulose fiber. The composite body is obtained by laminating the recycled carbon short fiber nonwoven fabric and a thermoplastic resin film.SELECTED DRAWING: None

Description

  The present invention relates to a recycled carbon short fiber nonwoven fabric and a composite formed by laminating a recycled carbon short fiber nonwoven fabric and a thermoplastic resin film.

  A carbon fiber reinforced resin composite formed by combining carbon fibers and a resin is a carbon fiber fabric such as a long fiber woven fabric, a spread fabric, a unidirectional web, a long fiber nonwoven fabric, and a short fiber nonwoven fabric, a thermosetting resin, It is a composite in which a resin such as a thermoplastic resin is combined. The most common carbon fiber reinforced resin composite is a composite comprising a carbon long fiber fabric and a thermosetting resin. The carbon fiber reinforced resin composite has a strength and elastic modulus comparable to that of a metal material, but has a specific gravity smaller than that of a metal material, so the weight of the member can be reduced, and there is no problem of rusting. Because it is resistant to acids and alkalis, electronic parts, electrical equipment materials, civil engineering materials, building materials, automotive materials, aircraft materials, robots and rolls used in various manufacturing parts Etc. are used. However, on the other hand, there is a problem of waste on the scale of several tens of thousands of tons per year, and a technique for recycling the waste material of the carbon fiber reinforced resin composite is required.

  As a recycling method of a carbon fiber reinforced resin composite, a method has been proposed in which a powder having a predetermined particle size is obtained by pulverizing the composite and is newly mixed with a resin (see, for example, Patent Document 1). ). However, in this method, although carbon fibers having a high aspect ratio are contained, it is difficult to say that the characteristics of carbon fibers are sufficiently exhibited because they are used as a pulverized product as a simple filler. Therefore, after the composite is cut, the resin is removed by sintering at 500 ° C. to 900 ° C., and the carbon fiber is taken out in a short fiber state and newly combined with a thermoplastic resin such as polypropylene and used. Has been proposed (see, for example, Patent Document 2). However, there is a problem that it is difficult to balance the sintering temperature and the sintering time, and the carbon fiber itself is easily damaged by heat.

  On the other hand, the utilization technology of the recycled carbon fiber obtained from the waste material of the carbon fiber reinforced resin composite is also examined, and the recycled carbon fiber reinforced resin composite containing the short carbon fiber (recycled carbon short fiber) is used. Attempts have been made to manufacture. As described above, composites in which carbon long fiber fabrics and thermosetting resins are combined are common, but there are problems such as difficult design, non-homogeneous materials, long molding time, and high costs. Recently, a carbon fiber reinforced thermoplastic resin composite in which a carbon short fiber nonwoven fabric and a thermoplastic resin are combined has been studied (for example, see Patent Documents 3 to 8).

  As a carbon fiber reinforced thermoplastic resin composite using a carbon short fiber nonwoven fabric, a carbon short fiber nonwoven fabric containing carbon short fibers and thermoplastic resin powder or fiber is laminated, and the carbon short fiber nonwoven fabric is melted. A composite formed by combining a thermoplastic resin or a solution / dispersion of a thermoplastic resin, a composite formed by laminating a carbon short fiber nonwoven fabric and a thermoplastic resin film, and the like are known. When manufacturing these carbon fiber reinforced thermoplastic resin composites, a heating or heating and pressing treatment is performed. In addition, the carbon fiber reinforced thermoplastic resin composite is formed into a molded product by being subjected to heat and pressure processing (hot press processing) as it is or in combination with other materials. Therefore, when manufacturing carbon reinforced thermoplastic resin composites (recycled carbon fiber reinforced thermoplastic resin composites) using recycled carbon short fibers, a nonwoven fabric containing recycled carbon short fibers (recycled carbon short fiber nonwoven fabric) is required. It is.

  For example, carbon fiber paper using recycled carbon fiber as a recycled carbon short fiber nonwoven fabric has been proposed (see, for example, Patent Document 9). However, this carbon fiber paper uses a recycled carbon fiber obtained by sintering or the like, and the carbon fiber is a powdered milled yarn or a chopped yarn (short fiber) of about several mm at the longest. It is difficult to say that this is a technology for effectively using recycled carbon fibers by laminating sheet-like materials made of new carbon fibers and recycled carbon fiber-containing sheets.

  In addition, as another recycled short carbon fiber nonwoven fabric, a recycled carbon short fiber obtained by sintering or the like and another short fiber-like thermoplastic resin fiber are mixed to form a web by a dry method. A method of compressing with hot pressure to obtain a recycled carbon short fiber sheet containing recycled carbon short fibers has been proposed (see, for example, Patent Document 10). However, this method does not take into account the adhesiveness between the recycled short carbon fiber and the thermoplastic resin fiber, and has left problems such as insufficient strength of the recycled short carbon fiber nonwoven fabric.

  And when manufacturing a recycled carbon fiber reinforced resin composite using the recycled carbon short fiber nonwoven fabric proposed in Patent Documents 3 and 4, when performing heating or heating and pressing treatment and heating and pressing processing, Due to the flow of the thermoplastic resin, the dispersibility of the recycled short carbon fibers is lost, and there is a problem that a uniform recycled carbon fiber reinforced thermoplastic resin composite or molded product cannot be obtained.

Japanese Patent No. 4565461 Japanese Patent No. 4454740 JP 2013-208791 A JP 2013-202891 A JP 2011-21303 A JP 2004-43985 A JP 2011-194852 A JP 2014-224333 A JP2013-249555A Special table 2013-519546 gazette

  The object of the present invention is to provide a recycled carbon fiber short during heating or heat-pressure treatment during the production of a recycled carbon fiber reinforced thermoplastic resin composite and during hot press processing for producing a molded product from the recycled carbon fiber reinforced thermoplastic resin composite. An object of the present invention is to provide a recycled carbon short fiber nonwoven fabric excellent in processability, in which the dispersibility of the fibers is not easily lost, and a composite formed by laminating the recycled carbon short fiber nonwoven fabric and a thermoplastic resin film.

  The above problems can be solved by the following invention.

(1) A recycled carbon short fiber nonwoven fabric comprising recycled carbon short fibers, thermoplastic resin fibers, and fibrillated cellulose fibers.

(2) The recycled carbon short fiber nonwoven fabric according to (1), wherein the blending ratio of the fibrillated cellulose fibers is 2 to 20% by mass with respect to all the fibers in the nonwoven fabric.

(3) A composite formed by laminating the recycled carbon short fiber nonwoven fabric according to (1) or (2) and a thermoplastic resin film.

  According to the present invention, when the recycled carbon fiber reinforced thermoplastic resin composite is heated or heated and pressed, and during the hot press process for producing a molded product from the recycled carbon fiber reinforced thermoplastic resin composite, the recycled carbon short It is possible to obtain a recycled short carbon fiber non-woven fabric that is less likely to lose the dispersibility of the fiber and has excellent processability. In the composite formed by laminating the recycled carbon short fiber nonwoven fabric and the thermoplastic resin film of the present invention, the uniformity of the carbon short fibers of the recycled carbon short fiber nonwoven fabric is maintained in heating or heat-pressing treatment and hot press processing. Therefore, a uniform recycled carbon fiber reinforced thermoplastic resin composite can be obtained.

  The recycled carbon short fiber nonwoven fabric of the present invention is a nonwoven fabric containing recycled carbon short fibers, thermoplastic resin fibers, and fibrillated cellulose fibers.

  The recycled carbon short fiber in the present invention is a recycled product obtained from a carbon fiber reinforced resin composite formed by combining carbon fiber and resin. A carbon fiber reinforced resin composite is a composite of carbon fiber fabrics such as long fiber woven fabrics, spread fabrics, unidirectional webs, long fiber nonwoven fabrics and short fiber nonwoven fabrics, and resins such as thermosetting resins and thermoplastic resins. This is a complex. The most common carbon fiber reinforced resin composite is a composite comprising a carbon long fiber fabric and a thermosetting resin. Examples of the carbon fiber include a PAN system using acrylic fiber and a pitch system carbon fiber using pitch. The short fiber-like carbon fiber obtained by removing the resin from the carbon fiber reinforced resin composite by a heat treatment method, a sintering method, a superheating method, a superheated steam method or the like is a recycled carbon short fiber. is there.

  In the present invention, when the recycled short carbon fiber is heat-treated in a gas containing oxygen such as in the atmosphere, the short carbon fiber itself is damaged. Therefore, it is preferable to heat-treat in a gas such as nitrogen, argon, or water vapor. The heat treatment temperature is preferably 400 ° C to 800 ° C, more preferably 450 ° C to 600 ° C.

  The fiber length of the recycled carbon short fiber depends on the production method of the composite as a raw material. For example, in a composite in which a carbon long fiber fabric and a thermosetting resin are combined, a plurality of prepregs, which are carbon long fiber fabrics impregnated with a thermosetting resin, are laminated and heated to cure the thermosetting resin. Manufactured by. The prepreg laminate structure includes a unidirectional ply in which the carbon long fibers of the entire composite are oriented in one direction and an orientation angle θ of 0 °, an orthogonal ply in which the orientation angles θ are in two directions of 0 ° and 90 °, and orientation There is an angle ply in which angles + θ and −θ (0 ° <θ <90 °) are stacked in combination. In the recycling process, since the composite as a raw material is cut into small pieces, the carbon fiber oriented perpendicular to the cutting direction, the carbon fiber oriented horizontally, and the fiber oriented obliquely have different fiber lengths after cutting. Therefore, the fiber length of the recycled carbon short fiber depends on the laminated configuration of the prepreg. In the present invention, the preferred fiber length of the recycled short carbon fiber is 3 mm to 500 mm, more preferably 6 mm to 150 mm.

  The thermoplastic resin fibers are added to prevent the recycled carbon short fibers from being detached from the nonwoven fabric and to impart strength to the recycled carbon short fiber nonwoven fabric. Thermoplastic resin fibers include non-crystalline polyvinyl alcohol (vinylon) short fibers, polyester core-sheath fibers whose surfaces have a low melting point, unstretched polyester fibers, polycarbonate (PC) fibers, polyolefin fibers, and low melting points on the surface. Polyolefin core-sheath fibers that have been formed, polyolefin fibers whose surface is made of acid-modified polyolefin, aliphatic polyamide fibers, unstretched polyphenylene sulfide fibers, polyether ketone ketone fibers, and the like.

  The melting point of the thermoplastic resin fiber is preferably 60 to 260 ° C, more preferably 60 to 230 ° C, still more preferably 60 to 180 ° C, and particularly preferably 80 to 160 ° C. When the melting point of the thermoplastic resin fiber is within this temperature range, the heat treatment in the nonwoven fabric manufacturing process imparts binding properties and imparts strength to the recycled carbon short fiber nonwoven fabric.

  The fiber diameter of the thermoplastic resin fiber is preferably 3 to 40 μm, and more preferably 5 to 20 μm. Moreover, it is preferable that the fiber length of a thermoplastic resin fiber is 1-20 mm, and it is more preferable that it is 3-12 mm.

  In the present invention, recycled carbon short fiber nonwoven fabric is recycled in combination with fibrillated cellulose fiber and thermoplastic resin fiber in addition to recycled carbon short fiber, at the time of heating or heat press treatment and hot press processing. It is possible to obtain a recycled carbon short fiber nonwoven fabric excellent in processability, in which the dispersibility of the carbon short fibers is not lost.

  The fibrillated cellulose fiber is not a film shape, but a fiber shape having a portion finely divided mainly in a direction parallel to the fiber axis, and at least a part thereof is a cellulose fiber having a fiber diameter of 1 μm or less. The aspect ratio of length to width is preferably 20 to 100,000. Moreover, it is preferable that modified drainage is 0-770 ml, and it is more preferable that it is 0-600 ml. Furthermore, the mass average fiber length is preferably 0.1 to 2 mm. The modified freeness in the present invention is that a wire mesh (made by PULP AND PAPER RESEARCH INSTITUTE OF CANADA) having a wire diameter of 0.14 mm and an aperture of 0.18 mm is used as a sieve plate, and the sample concentration is 0.1%. It is a freeness measured in accordance with JIS P8121 (1995 edition).

  The degree of fibrillation of fibrillated cellulose can also be grasped by the dispersion viscosity at a low concentration. As the viscosity increases, fibrillation progresses, but if the viscosity is too high, the fiber length may be too short. The viscosity of the fibrillated cellulose dispersion (concentration 0.5% by mass) is 50 to 200 cp when a B-type viscometer (rotor No. 2, rotor rotation speed 60 rpm, temperature 23 to 25 ° C.) is used. Is preferred.

  When the blending ratio of the fibrillated cellulose fibers is too small, the dispersibility of the recycled short carbon fibers may be lost when the heating temperature is too high during the heating or heating and pressurizing treatment and the hot pressing process. On the other hand, if the blending ratio of fibrillated cellulose fibers is too large, the fibrillated celluloses form a dense structure after dehydration during the production of the nonwoven fabric, forming a film, and inside the recycled carbon short fiber nonwoven fabric during hot press processing It becomes difficult for the thermoplastic resin film to enter. Moreover, a void may be seen in the composite body which laminates | stacks a recycled carbon short fiber nonwoven fabric and a thermoplastic resin fiber. The blending ratio of the fibrillated cellulose fiber is preferably 2 to 20% by mass, more preferably 2 to 15% by mass, and 5 to 15% by mass with respect to all the fibers in the nonwoven fabric. Further preferred.

  Cellulose materials for fibrillated cellulose fibers include vegetable pulp, solvent-spun cellulose, semi-synthetic cellulose and the like. Examples of plant pulp include woody pulp such as kraft pulp (KP), dissolved pulp (DP), and dissolved kraft pulp (DKP) using hardwood (L material) and softwood (N material). Moreover, non-woody pulps such as straw, hemp, cotton, and cotton linter are also included. As a commercially available product, serisch (registered trademark, manufactured by Daicel FineChem) can be mentioned. The crystal form of the cellulose material includes type I, type II, type III, type IV, and the like. From the viewpoint of heat resistance, type I and type II are preferable, and type I is more preferable. As the type I cellulose material source, non-woody pulp such as cotton pulp, cotton linter pulp, hemp pulp, kenaf pulp, etc., which is obtained from pulp with reduced lignin and hemicellulose content, L material or N material, And wood pulps such as KP, DP and DKP with a reduced content of hemicellulose. In particular, a cotton material is preferable.

  To obtain fibrillated cellulose, the cellulosic material is first dispersed in water and mechanically ground. And the fiber of a cellulose material is defibrated and a microfibril is formed. Examples of the device for defibrating the cellulose material include a disc refiner, a stone mill type grinder, a high-pressure homogenizer, a ball mill, an underwater counter collision method device, and an ultrasonic crusher. These devices can be used in appropriate combination.

  The content ratio (mass basis) of the recycled short carbon fiber and the thermoplastic resin fiber is preferably 8.5: 0.5 to 5: 4, and more preferably 8: 1 to 6: 3. By setting the content ratio of the recycled short carbon fiber and the thermoplastic resin within the above range, the strength of the recycled short carbon fiber nonwoven fabric, the composite, and the molded product can be increased.

  The recycled carbon short fiber nonwoven fabric in the present invention is preferably a wet papermaking nonwoven fabric produced by a wet papermaking method. In the wet papermaking method, first, recycled carbon short fibers, thermoplastic resin fibers, and fibrillated cellulose fibers are uniformly dispersed in water, and then passed through processes such as screen (removal of foreign matter, lumps, etc.) to obtain the final fiber concentration. The slurry adjusted to 0.01 to 0.50 mass% is made up by a paper machine to obtain a wet paper. In order to make the dispersibility of the fibers uniform, chemicals such as dispersants, antifoaming agents, hydrophilic agents, antistatic agents, polymer thickeners, mold release agents, antibacterial agents, bactericides, etc. may be added during the process. is there.

  As the paper machine, for example, a paper machine using a paper net such as a long net, a circular net, or an inclined wire alone, or a combination paper machine in which two or more paper nets of the same type or different types are installed online is used. be able to. In addition, when the nonwoven fabric has a multilayer structure of two or more layers, a paper making method in which wet papers made by each paper machine are laminated, or after one layer is formed, fibers are dispersed on the layer. The nonwoven fabric can be produced by a casting method in which the slurry is cast to form a laminate. When casting the slurry in which the fibers are dispersed, the previously formed layer may be either a wet paper state or a dry state. In addition, two or more dry layers can be heat-sealed to form a multilayered nonwoven fabric.

  In the present invention, when the nonwoven fabric has a multilayer structure, it may have a multilayer structure in which the fiber blend of each layer is the same, or may have a multilayer structure in which the fiber blend of each layer is different. In the case of a multilayer structure, since the fiber concentration of the slurry can be lowered by lowering the basis weight of each layer, the formation of the nonwoven fabric is improved, and as a result, the uniformity of the formation of the nonwoven fabric is improved. Moreover, even when the formation of each layer is non-uniform | heterogenous, it can compensate by laminating | stacking. Furthermore, the papermaking speed can be increased, and the operability can be improved.

  In the wet papermaking method, a wet papermaking nonwoven fabric in sheet form is obtained by drying wet paper produced by a papermaking net with a Yankee dryer, air dryer, cylinder dryer, suction drum dryer, infrared dryer, or the like. When the wet paper is dried, it is brought into close contact with a hot roll such as a Yankee dryer and dried by heat and pressure to improve the smoothness of the contacted surface. Hot-pressure drying means that wet paper is pressed against a hot roll with a touch roll or the like and dried. The surface temperature of the hot roll is preferably 100 to 180 ° C, more preferably 100 to 160 ° C, and still more preferably 110 to 160 ° C. The pressure is preferably 50 to 1000 N / cm, more preferably 100 to 800 N / cm.

  The composite of the present invention is a composite formed by laminating a recycled carbon short fiber nonwoven fabric and a thermoplastic resin film. The composite can be produced by superposing a recycled carbon short fiber nonwoven fabric and a thermoplastic resin film and subjecting the resultant to heat treatment or heat pressure treatment. A molded product can be produced by subjecting this composite to hot pressing (hot pressing).

  Examples of the thermoplastic resin of the thermoplastic resin film include polyolefin resins such as polyethylene resin, polypropylene resin and polybutylene resin; methacrylic resins such as polymethyl methacrylate resin; polystyrene resins such as polystyrene resin, ABS resin and AS resin; polyethylene Polyester resins such as terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate resin, polyethylene naphthalate (PEN) resin, poly 1,4-cyclohexyldimethylene terephthalate (PCT) resin; 6-nylon Polyamide (PA) resin such as resin, 6,6-nylon resin; polyvinyl chloride resin; polyoxymethylene (POM) resin; polycarbonate (PC) resin; polyphenylene sulfide (PP Modified polyphenylene ether (PPE) resin; polyetherimide (PEI) resin; polysulfone (PSF) resin; polyethersulfone (PES) resin; polyketone resin; polyarylate (PAR) resin; polyether nitrile (PEN) resin Polyetherketone (PEK) resin; Polyetheretherketone (PEEK) resin; Polyetherketoneketone (PEKK) resin; Polyimide (PI) resin; Polyamideimide (PAI) resin; Fluorine (F) resin; Liquid crystalline polymer resin: polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, or fluorine-based thermoplastic elastomer; or a copolymer resin or modified resin thereof; ionomer Resins. Among these resins, one type or two or more types can be used. From the viewpoint of combustibility, PC, PPS, PEEK, PEI and the like are preferable.

  Examples of the ionomer resin include an ethylene ionomer resin obtained by neutralizing a part of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer resin with a metal ion. A product obtained by neutralizing 10 mol% or more, preferably 10 to 90 mol%, of a carboxyl group with a metal ion is used. Examples of the metal ions include polyvalent metal ions such as alkali metals such as lithium and sodium, and alkaline earth metals such as zinc, magnesium and calcium.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples. In the examples, all parts and percentages are by mass unless otherwise specified.

(Production of fibrillated cellulose)
The linter pulp (mass average fiber length: 1.2 mm) was subjected to a grinding treatment using a mascolloider (registered trademark, apparatus name: MKZA12) manufactured by Masuko Sangyo Co., Ltd. to produce fibrillated cellulose. The viscosity of the fibrillated cellulose dispersion (concentration: 0.5 mass%) was measured with a B-type viscometer (rotor No. 2, rotor rotational speed 60 rpm, temperature 23 to 25 ° C.), and was 80 cp.

(Production of recycled carbon short fibers)
Carbon fiber reinforced resin composite (resin: epoxy resin, θ = 45 ° angle ply laminate, thickness: 30 mm, carbon fiber fiber diameter: 7 μm) is cut to a width of 100 mm, and further 6 mm apart in the length direction Cut with The laminated sheet after cutting was treated at 580 ° C. for 2 hours in a nitrogen atmosphere using an electric furnace to produce recycled carbon short fibers. The fiber length of the obtained recycled carbon short fiber was 6 mm to 80 mm.

(Thermoplastic fiber)
Thermoplastic resin fiber: Fiber diameter 4.5 μm, fiber length 3 mm, unstretched PET fiber

(Nonwoven fabric manufacturing)
With the fiber blending ratio shown in Table 1, the fiber is dispersed in water for 5 minutes at a dispersion concentration of 0.2% by mass to form a wet paper having a size of 25 cm × 25 cm with a 90 mesh metal wire. Drying was performed with a Yankee dryer at 0 ° C. to obtain a recycled carbon short fiber nonwoven fabric having a basis weight of 27 g / m ² .

(Manufacture of composite 1)
The front and back sides of the recycled carbon short fiber nonwoven fabrics produced in the examples and comparative examples are sandwiched between thermoplastic resin (PP containing acid-modified polypropylene (PP), melting point 160 ° C.) film, and the temperature is 160 ° C. and 5 MPa using a thermal breathing machine. After heating and pressurizing for 2 minutes, the mixture was cooled to room temperature to produce a composite 1.

(Manufacture of composite 2)
The recycled carbon short fiber nonwoven fabrics manufactured in Examples and Comparative Examples were sandwiched between thermoplastic resin (PEEK) films, heated and pressed with a hot press machine at a temperature of 360 ° C., 10 MPa, and then cooled to room temperature. And composite 2 was produced.

  The following evaluation was performed on the recycled short carbon fiber nonwoven fabrics and composites produced in Examples and Comparative Examples, and the results are shown in Table 2.

(Flexural modulus of composite)
Five test pieces having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm were cut out from the composites 1 and 2, and a universal material testing machine (TSE Co., Ltd., device name: Autocom (registered trademark, AutoCOM) AC- 100) and the flexural modulus was measured. The average results are shown in Table 2.

(State when manufacturing non-woven fabric)
When the dispersibility of the recycled carbon short fibers was confirmed on the surface of the metal wire, a state in which fibers of about 20 μm to 40 μm were partially bound was observed. Moreover, the presence or absence of detachment | desorption of the recycled carbon short fiber after drying with a Yankee dryer was confirmed.

(State of composites 1 and 2)
After the composites 1 and 2 were produced, it was confirmed whether or not a flow (flow) of recycled carbon short fibers occurred around the nonwoven fabric. In addition, the presence or absence of warpage of the composite and the occurrence of voids were also observed.

  The recycled carbon short fiber nonwoven fabric of Comparative Example 1 does not contain fibrillated cellulose fibers, but contains recycled carbon short fibers and thermoplastic resin fibers, and the state of the composite of Comparative Example 1 was observed. The flow of recycled carbon short fibers occurred around the nonwoven fabric. On the other hand, the recycled carbon short fiber nonwoven fabrics of Examples 1 to 9 contain recycled carbon short fibers, thermoplastic resin fibers, and fibrillated cellulose fibers. Therefore, in the composites of Examples 1 to 9, The flow of recycled short carbon fibers was suppressed. The flexural modulus of the composite was also improved in the composites of Examples 1 to 9 compared to the composite of Comparative Example 1.

  Comparing Examples 1 to 9, in Example 1 and Example 2 in which the blending ratio of fibrillated cellulose fibers is less than 5% by mass with respect to the total fibers of the nonwoven fabric, the flexural modulus of the composite is Example 3. When the state of the composite was observed slightly lower than that of Example 4, it was confirmed that there was a slight flow of short carbon fibers. Further, in Example 6 in which the blending ratio of the fibrillated cellulose fibers is more than 15% by mass with respect to the total fibers of the nonwoven fabric, the state of the composite was observed, but there was no flow of recycled carbon short fibers. Although it was acceptable, a small amount of void was confirmed.

  When Example 4 and 7-9 were compared, when the compounding rate of the thermoplastic resin fiber decreased, there was a tendency that detachment of the recycled carbon short fiber after drying was somewhat likely to occur. It was a level. Moreover, as the blending ratio of the thermoplastic resin fibers increases, the detachment of the fibers after drying is suppressed, but the blending ratio of the recycled carbon short fibers decreases, so that the flexural modulus tends to decrease. Although it is at a usable level, warpage is likely to occur in the composite.

  From the comparison between Example 4 and Comparative Example 2, the cellulose fibers are fibrillated to suppress the detachment of the recycled short carbon fibers, and the flow of the recycled short carbon fibers does not occur in the composite, and the flexural modulus is Was also confirmed to improve.

  In the nonwoven fabric of Comparative Example 3 that does not contain thermoplastic resin fibers and contains recycled carbon short fibers and fibrillated cellulose fibers, there was no fiber flow and the flexural modulus was good in the composite. There were many detachment | leaves of the fiber at the time of manufacture, and it was a useless level.

  The carbon short fiber nonwoven fabric and composite of the present invention can be used for manufacturing parts such as electronic equipment materials, electrical equipment materials, civil engineering materials, building materials, automobile materials, aircraft materials, robots and rolls used in various manufacturing industries, etc. It is.

Claims (3)

  A recycled carbon short fiber nonwoven fabric comprising recycled carbon short fibers, thermoplastic resin fibers, and fibrillated cellulose fibers.   The recycled carbon short fiber nonwoven fabric according to claim 1, wherein the blending ratio of the fibrillated cellulose fibers is 2 to 20% by mass with respect to all the fibers in the nonwoven fabric.   A composite formed by laminating the recycled carbon short fiber nonwoven fabric according to claim 1 or 2 and a thermoplastic resin film.