WO2016017469A1 - Combined filament yarn and manufacturing method thereof - Google Patents

Abstract

The purpose of the present invention is to provide a high-quality combined filament yarn which comprises a synthetic fiber material dispersed within a reinforcing fiber material, and to provide a manufacturing method thereof. In this combined filament yarn, a synthetic fiber material is combined into the reinforcing fiber material, which is drawn and aligned in a prescribed direction, the synthetic fiber material being drawn and aligned in the same direction as the reinforcing fiber material, and the synthetic fiber material is bonded to and integrated with the reinforcing fiber material. The synthetic fiber material is dispersed such that the standard deviation of the ratio of the cross-sectional area of the synthetic fiber material in partition regions partitioning the cross-section of the combined filament yarn is 25 or less.

Description

Blended yarn and method for producing the same

The present invention relates to a mixed yarn in which a reinforcing fiber material such as carbon fiber and a synthetic fiber material such as a thermoplastic resin are mixed, and a method for producing the same.

Fiber reinforced composite material is a combination of fiber material and matrix material, and it is lightweight, rigid and capable of various functional designs. It is widely used in aerospace field, transportation field, civil engineering field, exercise equipment field, etc. Used in the field. At present, fiber reinforced plastic (FRP: Fiber Reinforced Plastic) in which a reinforcing fiber material such as carbon fiber or glass fiber is combined with a synthetic resin material such as a thermosetting resin material or a thermoplastic resin material has become mainstream. Among the FRP, carbon fiber reinforced composite material using carbon fiber as the reinforcing fiber and thermoplastic resin material as the matrix resin (recyclability, short-time moldability, improved impact resistance of the molded product, etc.) CFRP (Carbon Fiber ； Reinforced Plastic) is expected to increase in the future.

For a fiber reinforced composite sheet material in which a reinforcing fiber material and a synthetic resin material are combined, for example, in Patent Document 1, a resin sheet obtained by laminating a resin on a release film with respect to a fiber body in which carbon fibers are aligned in one direction. It is described that a prepreg is manufactured by impregnating a fibrous body with a resin by superimposing and heating. In addition to the method of manufacturing a fiber reinforced composite material by superimposing a synthetic resin material serving as a matrix resin on such a reinforcing fiber material, a synthetic fiber material obtained by fiberizing a synthetic resin material serving as a matrix resin is mixed with a reinforcing fiber material. There has been proposed a method of producing a fiber reinforced composite material by producing a blended yarn and using the obtained blended yarn (see Non-Patent Document 1).

JP 2009-91377 A

Hiroyuki Hasebe, 2 others, “Prototype and properties evaluation of thermoplastic carbon fiber reinforced composite material using comingle yarn”, Abstracts of the Hokuriku branch meeting of the Japan Textile Machinery Society, p.11-p.12, The Japan Textile Machinery Society

In Patent Document 1, since a resin sheet is superimposed on a fiber body so as to be impregnated with the resin, the resin hardly permeates between the fibers, and voids (voids) are easily generated. Moreover, the manufacturing process etc. of a resin sheet are needed, and a process increases, and the enlargement of a manufacturing facility and the cost burden of an installation must become large. Further, in the method using a mixed yarn obtained by mixing a synthetic fiber material with a reinforcing fiber material, a mixed yarn in which a synthetic fiber material is arranged in advance between reinforcing fiber materials is used. In comparison with this, the resin easily penetrates between the reinforcing fiber materials, and the generation of voids is suppressed.

In such a method using mixed fiber, it is necessary to use a synthetic fiber material mixed as uniformly as possible to the reinforcing fiber material. Examples of conventional mixed yarn include those obtained by wrapping a sheath yarn around a core yarn by covering. However, in such a mixed yarn, a reinforcing fiber material and a synthetic fiber material are separated into two layers. It is difficult to obtain a uniformly mixed state.

Further, in Non-Patent Document 1, synthetic fibers made of carbon fiber and polyphenylene sulfide (PPS) are overlapped while being sent out at a constant speed, and air is blown to the overlapped portion by an air nozzle so that the fibers are entangled and mixed. I am doing so. However, in air entanglement in which air is blown, it is difficult to sufficiently mix both fibers, and carbon fibers are cut and fluffed during air entanglement, making it possible to produce a mixed yarn with good quality. There is a problem that it is difficult.

Therefore, an object of the present invention is to provide a blended yarn having a good quality in which a synthetic fiber material is dispersed and mixed between reinforcing fiber materials and a method for producing the same.

The mixed yarn according to the present invention is a mixed yarn obtained by mixing a synthetic fiber material aligned in the same direction as the reinforcing fiber material with respect to the reinforcing fiber material aligned in a predetermined direction, The synthetic fiber material is bonded and integrated with the reinforcing fiber material, and the synthetic fiber has a standard deviation of 25 or less in terms of the ratio of the cross-sectional area of the synthetic fiber material in the divided region where the cross-section of the mixed fiber is divided. The material is dispersed.

The method for producing a blended yarn according to the present invention includes a sheet-like reinforcing fiber material that has been opened and aligned in a predetermined direction, and is aligned in the same direction as the reinforcing fiber material. A polymerization step of superposing synthetic fiber materials in a state of being dispersed according to density; and an integration step of bonding and integrating the superposed reinforcing fiber material and synthetic fiber material. Further, in the polymerization step, the reinforcing fiber material and the synthetic fiber material that are superposed are subjected to fiber opening treatment. Furthermore, a yarn forming step of forming the reinforcing fiber material and the synthetic fiber material, which are bonded and integrated, into another form of yarn is provided.

The present invention can obtain a mixed yarn having a good quality in which a synthetic fiber material is dispersed and mixed between reinforcing fiber materials by having the above configuration. When a molded product is obtained using the mixed fiber of the present invention, a high-quality molded product free from voids can be obtained even under relatively mild molding conditions.

It is explanatory drawing regarding the process of manufacturing the mixed fiber which concerns on this invention. It is explanatory drawing regarding a superposition | polymerization process and an integration process. It is a typical sectional view of blended yarn. 2 is a photographed image related to a cross section of a mixed yarn related to Example 1. FIG. 6 is a photographed image relating to a cross section of a mixed yarn related to Example 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

FIG. 1 is an explanatory diagram relating to a process for producing a mixed fiber according to the present invention. First, the sheet | seat formation process which forms the reinforcing fiber material and synthetic fiber material used as the raw material of a mixed fiber in a sheet form is performed. In the case of the reinforcing fiber material, the fiber bundle is opened and formed into a thin sheet. As a method for opening the reinforcing fiber material, a method of opening the fiber bundle by bringing it into contact with a fiber opening roller, a vibrating roller, or the like, or running the fiber bundle so as to intersect the flow of the fluid and bending the fiber bundle There are known methods such as a method for opening fibers and a method for opening them in combination. In particular, the method of opening a fiber bundle while bending the fiber bundle using a fluid (for example, see Japanese Patent No. 3064019) can uniformly open the fiber without damaging the reinforcing fiber. It is suitable as a fiber opening method. Further, by arranging a plurality of fiber bundles in parallel in the width direction and simultaneously performing the fiber opening process, it can be easily formed into a wide sheet shape.

In the case of a synthetic fiber material, a fiber bundle can be formed into a thin sheet by warping using a warping machine or opening treatment similar to a reinforcing fiber material. Further, when a fiber material is produced by spinning from a synthetic resin material as a raw material, a thin layer sheet-like synthetic fiber material can be obtained by spinning in a state where the fiber material is arranged in a sheet shape.

Reinforcing fiber materials include, for example, carbon fibers, glass fibers, ceramic fibers, aramid fibers, PBO (polyparaphenylene benzobisoxazole) fibers, high-strength and high-modulus inorganic fibers and organic materials used in FRP Examples thereof include fibers. A plurality of fiber bundles in which these fibers are bundled may be combined. The fineness is not particularly limited.

Synthetic fiber materials are matrix (matrix) resins, such as polypropylene, polyethylene, polystyrene, polyamide (nylon 6, nylon 66, nylon 12, etc.), polyacetal, polycarbonate, acrylonitrile-butadiene-styrene copolymer (ABS ), Polyethylene terephthalate, polybutylene terephthalate, LPC (liquid crystal polyester), polyimide, polyetherimide, polyethersulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone and the like. Further, two or more of these thermoplastic resins may be mixed to form a polymer alloy and used as a base material (matrix) resin.

In addition, as the synthetic fiber material, a composite fiber material having a lower melting point of the surface portion than that of the central portion can be used in order to enhance the adhesiveness with the reinforcing fiber material in the integration step described later. For example, a composite fiber material having a core-sheath structure in which a high-melting synthetic resin material is used as the core portion and a low-melting synthetic resin material is used as the sheath portion. By using such a composite fiber material, if the sheath part is heated at a temperature lower than the melting point of the core part and higher than the melting point of the sheath part, the sheath part is securely bonded and integrated with the reinforcing fiber material while maintaining the fiber form. can do.

The use amount of the synthetic fiber material may be set in accordance with the use amount of the reinforcing fiber material, and is based on the fiber volume content (hereinafter abbreviated as “Vf value”) of the fiber-reinforced composite material using the mixed yarn. Can be set. And it is desirable for the fineness of the synthetic fiber material to have durability against tension applied when it is handled as a mixed yarn that easily enters between the reinforcing fibers.

Next, a polymerization process is performed in which the sheet-like synthetic fiber material is superimposed on the sheet-like reinforcing fiber material. FIG. 2 is an explanatory diagram relating to the polymerization step and the integration step. The sheet-like reinforcing fiber material T and the sheet-like synthetic fiber material S are conveyed in parallel in a state of being aligned in a predetermined direction and pass between the press-contact rolls R, whereby the sheet-like reinforcing fiber material The sheet-like synthetic fiber material is pressed on one side and set in a superposed state.

The synthetic fiber material S is arranged so as to be dispersed according to the density of the sheet-like reinforcing fiber material T. For example, when the reinforcing fiber material T is a thin layer and has a low density, a plurality of synthetic fiber materials S are arranged with a predetermined interval in accordance with the density and overlapped. Further, when the density of the reinforcing fiber material T is low or when the Vf value is set high, the reinforcing fiber material T may be superimposed on both surfaces of the synthetic fiber material S.

Further, in order to allow the synthetic fiber material S to enter between the reinforcing fiber materials T, the fiber-opening process can be performed in a superposed state as necessary. In FIG. 2, a fiber opening mechanism K is arranged on the downstream side in the conveying direction of the pressure roll R. In the fiber opening mechanism K, an air flow is conveyed while conveying the reinforcing fiber material T and the synthetic fiber material S in a superposed state. The fiber is opened by crossing and bending. The opening mechanism K may be a mechanism in which vibration rollers or the like are combined. Note that the tension applied to the reinforcing fiber material T and the synthetic fiber material S fluctuates during the fiber opening process, but when the synthetic fiber material S expands and contracts compared to the reinforcing fiber material T, the flow of airflow By arranging the synthetic fiber material S on the downstream side of the fiber, the fibers of the synthetic fiber material S are easily expanded and contracted during the fiber opening process, and easily enter between the reinforcing fibers.

As described above, since the synthetic fiber material can be dispersed and superposed in accordance with the density of the opened reinforcing fiber material, it is possible to mix the fibers in a more uniform state. In addition, the synthetic fiber material can be dispersed in advance in accordance with the processing of the yarn forming process described later, and the synthetic fiber material is overlapped so that the mixed fiber state of the finally manufactured mixed fiber yarn is uniform. Like that.

Next, an integration process for integrating the reinforcing fiber material and the synthetic fiber material in a superposed state is performed. In the example shown in FIG. 2, the synthetic fiber material S is temporarily bonded and integrated by passing between the heating rolls H while conveying the reinforcing fiber material T and the synthetic fiber material S in an overlapped state. . When the synthetic fiber material S is temporarily bonded, the synthetic fiber material S is partially melted and thermally fused to the reinforcing fiber material T by press-contacting with the heating roll H. It is adhered while maintaining the condition. For example, when the composite fiber material described above is used as the synthetic fiber material S, the sheath portion is reinforced by setting the temperature of the heating roll H to a temperature lower than the melting point of the core portion and higher than the melting point of the sheath portion. It can be integrated with the fiber material T while maintaining the form of the fiber by heat fusion.

Further, by temporarily adhering the synthetic fiber material to the reinforcing fiber material and integrating them, the opened reinforcing fiber material will not be scattered, and handling as a mixed fiber becomes easy. Moreover, since the reinforcing fiber material and the synthetic fiber material are integrated in a state where the fiber form is maintained, the tensile strength and the drapeability when weaving using the mixed yarn can be sufficiently provided. In addition, when the synthetic fiber material is temporarily bonded to the reinforcing fiber material, the synthetic fiber material may be bonded completely or partially as necessary. Or it can set to strip | belt shape and should just set suitably according to the use of a mixed fiber yarn.

Next, a yarn forming process for finishing the mixed yarn into various different types of yarn is performed. The product obtained by the integration process can be used as it is as a blended yarn, but when producing a blended yarn tailored to the intended use, the product obtained by the integration process is twisted, folded, and layered. By performing a yarn forming process such as slitting, various forms of mixed fiber can be produced. FIG. 3 is a schematic cross-sectional view of a mixed fiber. Fig.3 (a) has shown sectional drawing of the mixed fiber obtained by twisting the integrated reinforcement fiber material and synthetic fiber material with the well-known twist apparatus. The integrated reinforcing fiber material and synthetic fiber material are formed into a sheet shape, and are processed by being wound in the width direction by twisting, so that the synthetic fiber material is dispersed to the center of the blended yarn. A uniform mixed yarn can be obtained. FIG. 3B shows a cross-sectional view of a mixed fiber obtained by folding a plurality of integrated reinforcing fiber materials and synthetic fiber materials so that a crease is formed in the yarn length direction. In this case, the reinforcing fiber material and the synthetic fiber material are alternately laminated, and the synthetic fiber material can be dispersed to the central portion to obtain a more uniform mixed yarn. As a method of folding, it is possible to fold so as to wrap or zigzag, and fold so that the reinforcing fiber material and the synthetic fiber material are alternately laminated. FIG.3 (c) has shown sectional drawing of the mixed fiber obtained by laminating | stacking several sheets of the integrated reinforcing fiber material and synthetic fiber material. Also in this case, the reinforcing fiber material and the synthetic fiber material are alternately laminated, and the synthetic fiber material is dispersed to the central portion, so that a more uniform mixed yarn can be obtained. FIG. 3D is a cross-sectional view of the mixed fiber obtained by slitting the integrated reinforcing fiber material and synthetic fiber material in the yarn length direction. By forming the integrated reinforcing fiber material and synthetic fiber material into a wide sheet, slitting them into narrow widths and converging each, it becomes possible to produce multiple mixed yarns of the same quality at the same time. , Productivity can be greatly improved.

As described above, a synthetic fiber material is dispersed in accordance with the density of the spread sheet-like reinforcing fiber material, and is superposed and integrated to produce a mixed fiber that is more evenly mixed. Can do. The uniformity of the blended state of the obtained blended yarn can be confirmed by quantitatively analyzing the dispersion state of the synthetic fiber material in the cross section in the direction orthogonal to the yarn length direction of the blended yarn. For example, by dividing the cross section into a plurality of segmented areas, calculating the ratio of the cross-sectional area of the synthetic fiber material in each segmented area, and looking at the standard deviation regarding the calculated ratio of each area, the dispersion state can be quantitatively determined. Can be analyzed. In this case, the smaller the standard deviation is, the more uniformly the synthetic fiber material is dispersed, which indicates that a more uniform mixed fiber is obtained. In addition, when molding is performed by hot pressing or the like using blended yarn, the standard deviation σ is required in order for the synthetic fiber material to melt and penetrate between the reinforcing fiber materials and be filled in a void-free state. It is necessary to set it to 25 or less.

The conditions for forming by hot pressing using the mixed yarn according to the present invention can be a heating temperature of 260 ° C. to 320 ° C., a pressure of 0.1 MPa to 3.0 MPa, and a treatment time of 3 minutes to 20 minutes. . On the other hand, in the conventional method in which a resin sheet is superposed on the aligned carbon fibers and hot pressing is performed, the pressure is 10 MPa or more and the treatment time is 30 minutes or more. By using the mixed yarn of the present invention, a molded product free from voids can be obtained with a lower pressure and a shorter processing time. That is, a high-quality molded product can be efficiently produced by a simple heat press apparatus.

[Example 1]
A blended yarn was produced using the following materials.
<Materials used>
(Reinforcing fiber material)
Carbon fiber (Mitsubishi Rayon Co., Ltd .; 50R15L)
Fiber diameter 7μm Number of fibers 15000 (synthetic fiber material)
Polyethylene terephthalate (PET) composite fiber (KB Seiren Co., Ltd .; Belcouple (PET core-sheath type fused yarn, core-sheath weight ratio 1: 1))
Fineness 8 dtex The number of fibers used was 1000 carbon fibers and the amount of composite fiber was set so that the Vf value was 49.0%.
<Manufacturing process>
The carbon fiber was opened to a width of 100 mm by an opening method using an air flow described in Japanese Patent No. 3064019. The density of the obtained sheet-like carbon fiber was 150 fibers / mm. The composite fiber was warped to a width of 100 mm using a known warping machine. The density of the obtained sheet-like composite fiber was 10 fibers / mm. Next, the carbon fiber and the composite fiber formed in a sheet shape were superposed while being conveyed, and then a fiber-opening process similar to the carbon fiber opening method was performed to form a polymer sheet material having a width of 100 mm. And the composite fiber was temporarily bonded and integrated with respect to carbon fiber by letting the formed polymeric sheet material pass between heating rolls (170 degreeC). The obtained temporary adhesive sheet material was folded four times along the fold line in the yarn length direction to produce a mixed yarn laminated in 16 layers.

<Evaluation of uniformity of blended yarn>
The produced mixed yarn was cut in a direction perpendicular to the yarn length direction, and a cross-section was photographed with a scanning electron microscope (S-3500N manufactured by Hitachi High-Technologies Corporation). FIG. 4 is a photographed image relating to the cross section of the blended yarn. In order to evaluate the uniformity of the mixed yarn, the captured image of the cross section of the mixed yarn was processed to evaluate the dispersion state of the area of the composite fiber. Commercially available image processing software (Olympus Stream Essential) was used for processing the captured image. First, a region to be analyzed was defined by drawing a rectangle circumscribing the cross section of the mixed yarn, and nine divided regions were set by dividing the defined rectangular region into three equal parts. In FIG. 4, the divided areas are indicated by white straight lines.

The contour line is drawn so as to trace the outer shape of the blended yarn for each segmented region, and the area S1 of the blended yarn surrounded by the drawn contour line and the boundary line of the segmented region is calculated. Next, an area S2 of the composite fiber surrounded by drawing a surrounding line surrounding only the composite fiber is calculated. In FIG. 4, the outline and the surrounding line are shown by white curves. And the fiber mixture ratio M is computed by the following formula | equation.
M (%) = S2 / S1 × 100
Then, the standard deviation σ is calculated with respect to the blend ratio M calculated for each of the nine divided regions. The standard deviation σ of the mixed fiber of Example 1 was 9.3.

[Example 2]
The same material as in Example 1 was used, and the integration process was performed from the sheet forming process in the same manner as in Example 1. The obtained temporary adhesive sheet material was twisted 100 times / m by a known twisting device to produce a mixed fiber. A cross-section of the manufactured mixed yarn was photographed in the same manner as in Example 1. FIG. 5 is a photographed image relating to the cross section of the blended yarn. For uniformity evaluation, image processing was performed on the cross-sectional image in the same manner as in Example 1, and the standard deviation was calculated. The standard deviation σ was 11.5.

[Example 3]
The same material as in Example 1 was used, and the integration process was performed from the sheet forming process in the same manner as in Example 1. The obtained temporary adhesive sheet material was spirally wound in the width direction to produce a mixed yarn. A cross-section of the manufactured mixed yarn was photographed in the same manner as in Example 1. Then, for uniformity evaluation, image processing was performed on the cross-sectional image in the same manner as in Example 1, and a standard deviation was calculated. The standard deviation σ was 15.2.

[Example 4]
The same material as in Example 1 was used, and the integration process was performed from the sheet forming process in the same manner as in Example 1. The obtained temporary adhesive sheet material was slit in the yarn length direction with a width of 2 mm by a known slitter to produce a mixed fiber. A cross-section of the manufactured mixed yarn was photographed in the same manner as in Example 1. Then, for uniformity evaluation, image processing was performed on the cross-sectional image in the same manner as in Example 1, and a standard deviation was calculated. The standard deviation σ was 19.2.

[Comparative Example 1]
<Materials used>
(Reinforcing fiber material)
The same carbon fiber as in Example 1 was used.
(Synthetic fiber material)
Polyester fibers (KB Selen Co., Ltd .; Bell Couple) 280T / 16f 30 carbon fibers and polyester fibers were used so that the Vf value was 47.5%.
<Manufacturing process>
Polyester fibers were divided into two fiber bundles of 15 each, and double-covering treatment was performed on the two fiber bundles with a covering device centering on the carbon fiber to produce a mixed yarn. The number of windings of the fiber bundle was set to 200 times / m.

For the manufactured mixed fiber, for uniformity evaluation, a cross-sectional image was taken in the same manner as in Example 1, image processing was performed, and a standard deviation was calculated. The standard deviation σ was 30.6.

[Example 5]
Next, using the mixed yarn obtained in Example 1, the permeability of the composite fiber by hot pressing was evaluated. The mixed yarn was set in a hot press apparatus (IMC-180C type manufactured by Imoto Seisakusho Co., Ltd.), set to a heating temperature of 300 ° C. and a pressing force of 0.14 MPa, and subjected to a hot press treatment for 5 minutes. The mixed yarn was molded into a plate-like body having a width of about 4.5 mm and a thickness of about 0.4 mm. When the molded plate was cut in the thickness direction and the cross section was observed with an electron microscope, the resin was filled between the carbon fibers exposed in the cross section, and no void was observed.

[Example 6]
The mixed yarn obtained in Example 2 was heat-pressed in the same manner as in Example 5 to form a plate-like body. When the molded plate was cut in the thickness direction and the cross section was observed with an electron microscope, the resin was filled between the carbon fibers exposed in the cross section, and no void was observed.

[Comparative Example 2]
The mixed yarn obtained in Comparative Example 1 was heat-pressed in the same manner as in Example 5 to form a plate-like body. When the molded plate-like body was cut in the thickness direction and the cross section was observed with an electron microscope, voids in which the resin did not permeate between the carbon fibers exposed in the cross section were observed.

[Example 7]
Except that the heat treatment temperature was set at 280 ° C. and the applied pressure was set at 1.29 MPa, a hot press treatment was performed in the same manner as in Example 5 to form a plate-like body. When the molded plate was cut in the thickness direction and the cross section was observed with an electron microscope, the resin was filled between the carbon fibers exposed in the cross section, and no void was observed.

[Comparative Example 3]
Carbon fiber (Mitsubishi Rayon Co., Ltd .; 50R15L) is aligned, polyethylene terephthalate film (Fujimori Kogyo Co., Ltd .; 75-NT2-AS) is overlaid, and heat-pressed under the same conditions as in Example 7. Molded into a plate. When the molded plate-like body was cut in the thickness direction and the cross section was observed with an electron microscope, voids in which the resin did not permeate between the carbon fibers exposed in the cross section were observed.

From the above Examples and Comparative Examples, it can be seen that when the standard deviation indicating the dispersion state of the synthetic fiber material of the blended yarn is 25 or less, a molded product without voids can be obtained.

H ... heating roll, K ... opening mechanism, R ... pressure contact roll, S ... synthetic fiber material, T ... reinforcing fiber material

Claims (5)

A synthetic fiber obtained by mixing a synthetic fiber material aligned in the same direction as the reinforcing fiber material with a reinforcing fiber material aligned in a predetermined direction, wherein the synthetic fiber material is the reinforcing fiber A blended yarn in which the synthetic fiber material is dispersed and adhered so as to have a standard deviation of 25 or less with respect to the ratio of the cross-sectional area of the synthetic fiber material in a divided region where the cross section of the blended yarn is divided. . A molded product molded using the mixed yarn according to claim 1. Synthetic fiber material in a state in which it is aligned in the same direction as the reinforcing fiber material and dispersed according to the density of the reinforcing fiber material with respect to the sheet-like reinforcing fiber material opened and aligned in a predetermined direction A method for producing a blended yarn, comprising: a polymerization step of superimposing the two, and an integration step of bonding and integrating the superimposed reinforcing fiber material and the synthetic fiber material. The method for producing a blended yarn according to claim 3, wherein, in the polymerization step, the reinforcing fiber material and the synthetic fiber material that have been superposed are subjected to fiber opening treatment. The method for producing a blended yarn according to claim 3 or 4, further comprising a yarn forming step of forming the reinforcing fiber material and the synthetic fiber material which are bonded and integrated into a yarn of another form.

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