Method for producing particle-containing fiber bundle, and particle-containing fiber bundle

Abstract

Provided are: a particle-containing fiber bundle which has high uniformity and further improved feeding efficiency; and a method for producing the particle-containing fiber bundle. A method for producing a particle-containing fiber bundle of the present invention is a method for producing a particle-containing fiber bundle of a long ball shape or a strand shape, the method comprising a step for mixing a plurality of short fibers, particles having a median diameter of 100 [mu] m or less, an organic binder, and a liquid, the method including carbon fibers as the fibers, and the amount of the organic binder being 100 parts by mass per 100 parts by mass of the fibers. 10 parts by mass or more of the particles are used.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a fiber bundle containing particles and a fiber bundle containing particles.

[0002] This application claims priority based on Japanese Patent Application No. 2022-200735 filed in Japan on December 16, 2022, and Japanese Patent Application No. 2022-201050 filed in Japan on December 16, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Carbon fibers are mixed and dispersed in a matrix such as a resin to produce an industrially important material for improving mechanical or electrical properties such as high strength, high rigidity, low specific gravity, high conductivity, and high wear resistance, and are used for various purposes.

[0004] Generally, in the case of obtaining a fiber-reinforced resin composition by mixing and dispersing short-sized carbon fibers in various resins, a form of carbon fiber that facilitates the treatment of carbon fibers and thus enables efficient operation in the mixing and dispersing process is used. In particular, stable and smooth feeding of carbon fibers into a kneader, a molding die, etc. is required. As a method thereof, a method of cutting a continuous carbon fiber bundle treated with a sizing agent or the like to produce so-called chopped carbon fibers, and a method of granulating the cut carbon fibers to produce a carbon fiber bundle are used.

[0005] Carbon fiber-reinforced thermoplastics can be manufactured by a method of adding carbon fiber particles to a thermoplastic resin. As a method for manufacturing carbon fiber particles, for example, a method is disclosed in which short-sized carbon fibers are mixed with a solution or suspension of a sizing agent to form a carbon fiber aggregate, which is granulated with a disk granulator and then dried (Patent Document 1). Thereby, carbon fiber particles having a high density and a streamlined shape can be obtained, and carbon fibers can be fed stably and smoothly.

[0006] As a method for obtaining carbon fiber particles using recycled fibers, a method of thermally decomposing carbon fibers before cutting or crushing is disclosed (Patent Document 2), which includes: cutting and / or crushing carbon fibers into a predetermined average length, mixing the carbon fibers with a solution or suspension in a mixer to form an aggregate, concentrating the aggregate by bringing it into contact with an inclined rotating surface, and further drying the aggregate to produce carbon fiber particles.

[0007] In addition, as a method for improving the feeding efficiency of carbon fiber particles using recycled fibers, a method in which a mixture further contains thermoplastic resin fibers in a method of manufacturing carbon fiber particles by rotating a mixture composed of carbon fibers and a binder-containing liquid in a container is disclosed (Patent Document 3).

[0008] Prior Art Documents

[0009] Patent Document

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 10-503812

[0011] Patent Document 2: European Patent Application Publication No. 2902433 Specification

[0012] Patent Document 3: International Publication No. 2022 / 210591 Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] According to the research of the present inventors, in the method described in the above Patent Document 1, in the case of using recycled fiber as the raw material for carbon fiber, sufficient feeding efficiency may sometimes not be obtained.

[0015] One of the objects of the present invention is to provide a particle-containing fiber bundle with high uniformity and further improved feeding efficiency, and a method for manufacturing the same. One of the objects of the present invention is to provide a particle-containing fiber bundle with high uniformity and further improved feeding efficiency, especially in the case of using recycled fiber as the raw material for carbon fiber, and a method for manufacturing the same.

[0016] Method for Solving the Problems

[0017] The present invention includes the following embodiments.

[0018] [1]: A method for manufacturing a particle-containing fiber bundle, which is a method for manufacturing a particle-containing fiber bundle in an oblate spheroid shape or a strand shape, including: a step of mixing a plurality of fibers having been shortened in size, particles having a median particle diameter of 100 μm or less, an organic binder, and a liquid, and as the above fibers, carbon fibers are included, and 10 parts by mass or more of the above particles are used with respect to 100 parts by mass of the above fibers.

[0019] [2]: The method for manufacturing a particle-containing fiber bundle according to [1], wherein the median particle diameter of the above particles is 3 μm or more.

[0020] [3]: The method for manufacturing a particle-containing fiber bundle according to [1] or [2], wherein the solubility of the above particles in the above liquid is 0.01 g / 100 g or less.

[0021] [4]: The method for manufacturing a particle-containing fiber bundle according to any one of [1] to [3], wherein the solubility of the above particles in water is 0.0001 g / 100 g or less.

[0022] [5]: The method for manufacturing a particle-containing fiber bundle according to [4], wherein the solubility of the above organic binder in water is greater than 0.0001 g / 100 g.

[0023] [6]: The method for manufacturing a particle-containing fiber bundle according to any one of [1] to [5], wherein the particles include organic particles.

[0024] [7]: The method for manufacturing a particle-containing fiber bundle according to any one of [1] to [6], wherein 20 to 80 parts by mass of the above particles are used relative to 100 parts by mass of the above fibers.

[0025] [8]: The method for manufacturing a particle-containing fiber bundle according to any one of [1] to [7], wherein 55 to 75 parts by mass of the above particles are used relative to 100 parts by mass of the above fibers.

[0026] [9]: The method for manufacturing a particle-containing fiber bundle according to any one of [1] to [8], wherein the organic binder includes at least one resin selected from the group consisting of polyamide resins, epoxy resins, unsaturated polyester resins, vinyl ester resins, and polyurethane resins.

[0027]

[10] : The method for manufacturing a particle-containing fiber bundle according to any one of [6] to [9], wherein the organic particles include thermoplastic resin particles.

[0028]

[11] : The method for manufacturing a particle-containing fiber bundle according to

[10] , wherein the thermoplastic resin particles include at least one selected from the group consisting of polyamide resins, polyolefin resins, polyester resins, polycarbonate resins, polyethersulfone resins, polyetheretherketone resins, polyetherimide resins, and polyphenylene sulfide resins.

[0029]

[12] : The method for manufacturing a particle-containing fiber bundle according to any one of [6] to

[11] , wherein the organic particles include thermosetting resin particles.

[0030]

[13] : The method for manufacturing a particle-containing fiber bundle according to

[12] , wherein the thermosetting resin particles include at least one selected from the group consisting of epoxy resins, vinyl ester resins, unsaturated polyester resins, cyanate ester resins, polyimide resins, maleimide resins, silicone resins, melamine resins, urea resins, alkyd resins, polyurethane resins, and phenolic resins.

[0031]

[14] : The method for manufacturing a particle-containing fiber bundle according to any one of [6] to

[13] , wherein the organic particles include curing agent particles.

[0032]

[15] : The method for manufacturing a particle-containing fiber bundle according to

[14] , wherein the curing agent particles include at least one selected from the group consisting of dicyandiamide-based compounds, phenols, amines, carboxylic anhydrides, thiols, imidazoles, phosphines, peroxides, and organic metal salts.

[0033]

[16] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[15] , wherein the particles include inorganic particles.

[0034]

[17] : The method for manufacturing a particle-containing fiber bundle according to

[16] , wherein the inorganic particles include at least one selected from the group consisting of metal particles, metal oxide particles, silica particles, silicate particles, carbonate particles, sulfate particles, hydroxide particles, glass particles, ceramic particles, graphite, and carbon black.

[0035]

[18] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[17] , wherein the particle diameter D90 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 90% is 250 μm or less.

[0036]

[19] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[18] , wherein the particle diameter D10 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 10% is 50 μm or less.

[0037]

[20] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[19] , wherein the particle diameter D90 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 90% is 0.5 μm or more.

[0038]

[21] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[20] , wherein the particle diameter D10 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 10% is 0.05 μm or more.

[0039]

[22] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[21] , wherein the ratio (D75 / D25) of the particle diameter D75 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 75% to the particle diameter D25 at which the cumulative value becomes 25% is 1 to 15.

[0040]

[23] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[22] , wherein a fiber batting containing the above fibers is used.

[0041]

[24] : The method for manufacturing a particle-containing fiber bundle according to any one of [1] to

[23] , wherein a stirring granulator is used.

[0042]

[25] : The method for manufacturing a particle-containing fiber bundle according to

[24] , wherein the stirring granulator includes a stirring tank.

[0043]

[26] : The method for manufacturing a particle-containing fiber bundle according to

[25] , wherein stirring blades are provided inside the stirring tank.

[0044]

[27] : The manufacturing method of the particle-containing fiber bundle according to

[25] or

[26] , wherein the stirring tank is equipped with a scraper.

[0045]

[28] : The manufacturing method of the particle-containing fiber bundle according to

[26] or

[27] , wherein the distance between the stirring blade and the wall surface of the stirring tank is 1 mm or less.

[0046]

[29] : The manufacturing method of the particle-containing fiber bundle according to any one of

[26] to

[28] , wherein the distance between the stirring blade and the wall surface of the stirring tank is 10 mm or more.

[0047]

[30] : The manufacturing method of the particle-containing fiber bundle according to any one of

[25] to

[29] , wherein the stirring tank is rotated.

[0048]

[31] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[30] , wherein the average fiber length of the fibers is 12 to 50 mm.

[0049]

[32] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[30] , wherein the average fiber length of the fibers is 2 to 12 mm.

[0050]

[33] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[32] , wherein the volume density of the fibers is 0.01 to 0.1 g / cm 3 .

[0051]

[34] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[33] , wherein the front end positions of the fibers constituting the particle-containing fiber bundle are inconsistent.

[0052]

[35] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[34] , wherein the length of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the particle-containing fiber bundle.

[0053]

[36] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[35] , comprising: obtaining a mixture 1 by mixing the particles, the organic binder, and the liquid; and obtaining a mixture 2 by mixing the mixture 1 and the fibers.

[0054]

[37] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[36] , comprising removing the liquid.

[0055]

[38] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[37] , wherein 60 to 200 parts by mass of the above liquid is used with respect to 100 parts by mass of the above fiber.

[0056]

[39] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[38] , wherein 1 to 40 parts by mass of the above organic binder is used with respect to 100 parts by mass of the above fiber.

[0057]

[40] : The manufacturing method of the particle-containing fiber bundle according to any one of [1] to

[39] , wherein the above particles and the above organic binder are used such that the mass ratio of the above particles to the above organic binder (mass of particles / mass of organic binder) becomes 2.5 to 100.

[0058]

[41] : A manufacturing method of a particle-containing fiber bundle, the above particle-containing fiber bundle includes a plurality of short-sized fibers, particles having a median particle size of 100 μm or less, and an organic binder, and has a long spherical shape or a strand shape, and the above fibers are aligned.

[0059]

[42] : The manufacturing method of the particle-containing fiber bundle according to

[41] , wherein carbon fiber is included as the above fiber.

[0060]

[43] : The manufacturing method of the particle-containing fiber bundle according to

[41] or

[42] , wherein the median particle size of the above particles is 3 μm or more.

[0061]

[44] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[43] , wherein the solubility of the above particles in water is 0.0001 g / 100 g or less.

[0062]

[45] : The manufacturing method of the particle-containing fiber bundle according to

[44] , wherein the solubility of the above organic binder in water is greater than 0.0001 g / 100 g.

[0063]

[46] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[45] , wherein the average fiber length of the above fibers is 12 to 50 mm.

[0064]

[47] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[45] , wherein the average fiber length of the above fibers is 2 to 12 mm.

[0065]

[48] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[47] , wherein the front end positions of the fibers constituting the above particle-containing fiber bundle are not consistent.

[0066]

[49] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[48] , wherein the length of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the particle-containing fiber bundle.

[0067]

[50] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[49] , wherein the ratio of the length of the particle-containing fiber bundle to the average fiber length of the fibers contained in the particle-containing fiber bundle (length of the particle-containing fiber bundle / average fiber length of the fibers contained in the particle-containing fiber bundle) is 1.1 to 2.5.

[0068]

[51] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[50] , wherein the mass content rate of the particles in the particle-containing fiber bundle is 20 to 80 mass%.

[0069]

[52] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[51] , wherein the mass content rate of the organic binder in the particle-containing fiber bundle is 0.5 to 20 mass%.

[0070]

[53] : The manufacturing method of the particle-containing fiber bundle according to any one of

[41] to

[52] , wherein the mass ratio of the particles to the organic binder in the particle-containing fiber bundle (mass of the particles / mass of the organic binder) is 2.5 to 100.

[0071]

[54] : A manufacturing method of a particle-containing fiber bundle, comprising: mixing a mixture containing carbon fiber cotton containing a plurality of short-sized fibers, particles having a median particle size of 100 μm or less, at least one resin selected from the group consisting of polyamide resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, and polyurethane resin, and water.

[0072]

[55] : The manufacturing method of the particle-containing fiber bundle according to

[54] , wherein the solubility of the particles in water is 0.0001 g / 100 g or less.

[0073]

[56] : The manufacturing method of the particle-containing fiber bundle according to

[54] or

[55] , wherein the particles include at least one resin particle selected from the group consisting of polyamide resin, polyether ether ketone resin, polyetherimide resin, polyphenylene sulfide resin, epoxy resin, and vinyl ester resin.

[0074]

[57] : A particle-containing fiber bundle, which includes a plurality of short-sized fibers, particles having a median particle size of 100 μm or less, and an organic binder, and has an oblong spherical shape or a strand shape. As the fibers, it includes carbon fibers, and contains 10 mass parts or more of the particles relative to 100 mass parts of the fibers.

[0075]

[58] : The particle-containing fiber bundle according to

[57] , wherein the above-mentioned fibers are aligned.

[0076]

[59] : The particle-containing fiber bundle according to

[57] or

[58] , wherein the above-mentioned particles include organic particles.

[0077]

[60] : The particle-containing fiber bundle according to

[59] , wherein the above-mentioned organic particles include thermoplastic resin particles.

[0078]

[61] : The particle-containing fiber bundle according to

[60] , wherein the above-mentioned thermoplastic resin particles include at least one selected from the group consisting of polyamide resin, polyolefin resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyetheretherketone resin, polyetherimide resin, and polyphenylene sulfide resin.

[0079]

[62] : The particle-containing fiber bundle according to any one of

[59] to

[61] , wherein the above-mentioned organic particles include thermosetting resin particles.

[0080]

[63] : The particle-containing fiber bundle according to

[62] , wherein the above-mentioned thermosetting resin particles include at least one selected from the group consisting of epoxy resin, vinyl ester resin, unsaturated polyester resin, cyanate ester resin, polyimide resin, maleimide resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane resin, and phenolic resin.

[0081]

[64] : The particle-containing fiber bundle according to any one of

[59] to

[63] , wherein the above-mentioned organic particles include curing agent particles.

[0082]

[65] : The particle-containing fiber bundle according to

[64] , wherein the above-mentioned curing agent particles include at least one selected from the group consisting of dicyandiamide-based, phenols, amines, carboxylic anhydrides, thiols, imidazoles, phosphines, peroxides, and organic metal salts.

[0083]

[66] : The particle-containing fiber bundle according to any one of

[57] to

[65] , wherein the median particle size of the above-mentioned particles is 3 μm or more.

[0084]

[67] : The particle-containing fiber bundle according to any one of

[57] to

[66] , wherein the average fiber length of the above-mentioned fibers is 12 to 50 mm.

[0085]

[68] : The particle-containing fiber bundle according to any one of

[57] to

[66] , wherein the average fiber length of the above-mentioned fibers is 2 to 12 mm.

[0086]

[69] : In the particle-containing fiber bundle according to any one of

[57] to

[68] , the front end positions of the fibers constituting the particle-containing fiber bundle are not consistent.

[0087]

[70] : In the particle-containing fiber bundle according to any one of

[57] to

[69] , the length of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the particle-containing fiber bundle.

[0088]

[71] : In the particle-containing fiber bundle according to any one of

[57] to

[70] , the ratio of the length of the particle-containing fiber bundle to the average fiber length of the fibers contained in the particle-containing fiber bundle (length of the particle-containing fiber bundle / average fiber length of the fibers contained in the particle-containing fiber bundle) is 1.1 to 2.5.

[0089]

[72] : In the particle-containing fiber bundle according to any one of

[57] to

[71] , the mass content rate of the particles in the particle-containing fiber bundle is 20 to 80 mass%.

[0090]

[73] : In the particle-containing fiber bundle according to any one of

[57] to

[72] , the mass content rate of the organic binder in the particle-containing fiber bundle is 0.5 to 20 mass%.

[0091]

[74] : In the particle-containing fiber bundle according to any one of

[57] to

[73] , the mass ratio of the particles to the organic binder in the particle-containing fiber bundle (mass of the particles / mass of the organic binder) is 2.5 to 100.

[0092]

[75] : In the particle-containing fiber bundle according to any one of

[57] to

[74] , as the fiber, it contains regenerated fiber.

[0093]

[76] : In the particle-containing fiber bundle according to any one of

[57] to

[75] , as the organic binder, it contains at least one resin selected from the group consisting of polyamide resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, and polyurethane resin.

[0094]

[77] : In the particle-containing fiber bundle according to any one of

[57] to

[76] , fiber cotton containing the above fibers is used.

[0095]

[78] : In the particle-containing fiber bundle according to any one of

[57] to

[77] , the particle diameter D10 at which the cumulative value in the volume-based particle size distribution of the particles becomes 10% is 50 μm or less.

[0096]

[79] : In the particle-containing fiber bundle according to any one of

[57] to

[78] , the particle diameter D90 at which the cumulative value in the volume-based particle size distribution of the particles becomes 90% is 0.5 μm or more.

[0097]

[80] : For the particle-containing fiber bundle according to any one of

[57] to

[79] , the particle diameter D10 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 10% is 0.05 μm or more.

[0098]

[81] : For the particle-containing fiber bundle according to any one of

[57] to

[80] , the ratio (D75 / D25) of the particle diameter D75 at which the cumulative value in the volume-based particle size distribution of the above particles becomes 75% to the particle diameter D25 at which it becomes 25% is 1 to 15.

[0099]

[82] : For the particle-containing fiber bundle according to any one of

[57] to

[81] , the ratio of the average fiber diameter of the above fibers to the median particle diameter of the above particles (average fiber diameter of the fibers (μm) / median particle diameter of the particles (μm)) is 0.01 to 0.4.

[0100]

[83] : A particle-containing fiber bundle, which includes a plurality of short-sized fibers, polyether ether ketone resin particles, and an organic binder, and has an oblong spherical shape or a strand shape.

[0101]

[84] : For the particle-containing fiber bundle according to

[83] , as the above fibers, carbon fibers are included.

[0102]

[85] : For the particle-containing fiber bundle according to

[83] or

[84] , the median particle diameter of the above resin particles is 0.1 μm or more and 100 μm or less.

[0103]

[86] : For the particle-containing fiber bundle according to any one of

[83] to

[85] , the ratio of the length of the particle-containing fiber bundle to the average fiber length of the fibers contained in the particle-containing fiber bundle (length of the particle-containing fiber bundle / average fiber length of the fibers contained in the particle-containing fiber bundle) is 1.1 to 2.5.

[0104]

[87] : For the particle-containing fiber bundle according to any one of

[83] to

[86] , the average fiber length of the above fibers is 1 to 100 mm.

[0105]

[88] : For the particle-containing fiber bundle according to any one of

[83] to

[87] , the average fiber length of the above fibers is 12 to 50 mm.

[0106]

[89] : For the particle-containing fiber bundle according to any one of

[83] to

[87] , the average fiber length of the above fibers is 2 to 12 mm.

[0107]

[90] : The particle-containing fiber bundle according to any one of

[83] to

[89] , as the above-mentioned organic binder, contains at least one resin selected from the group consisting of polyamide resin, epoxy resin, and polyurethane resin.

[0108] Advantages of the Invention

[0109] According to one embodiment of the present invention, it is possible to provide a particle-containing fiber bundle with high uniformity and further improved feeding efficiency, and a method for manufacturing the same. According to one embodiment of the present invention, it is possible to provide a particle-containing fiber bundle with high uniformity and further improved feeding efficiency, especially in the case of using recycled raw materials as raw materials for carbon fibers, and a method for manufacturing the same.

[0110] According to a preferred embodiment of the present invention, a particle-containing fiber bundle with improved feeding efficiency can be obtained. In addition, the size of the particle-containing fiber bundle can be easily adjusted. Even when using a fiber cotton raw material, a particle-containing fiber bundle with improved feeding efficiency and resin impregnation can be easily obtained. Description of the Drawings

[0111] Figure 1A Figure 1A is a view showing an embodiment of a stirring granulator, which is a horizontal cross-sectional view of a stirring tank.

[0112] Figure 1B Figure 1B is a cross-sectional view along the Figure 1A b-b line.

[0113] Figure 2 Figure 2 is an internal perspective three-dimensional view showing an embodiment of a rotating stirring granulator.

[0114] Figure 3 Figure 3 is a photograph showing a morphological example of recycled fibers.

[0115] Figure 4 Figure 4 is a photograph showing a morphological example of virgin fibers.

[0116] Figure 5 Figure 5 is an image obtained by photographing the particle-containing fiber bundle obtained in Example 1.

[0117] Figure 6 Figure 6 is an image showing the appearance of the particle-containing fiber bundle obtained in Example 1.

[0118] Figure 7 Figure 7 ​​​​​​​​​​​​​​​​This is an image showing the cross-section of the particle-containing fiber bundle obtained in Example 1. Detailed Description of the Invention

[0119] Hereinafter, the present invention will be described in detail.

[0120] [Method for Manufacturing Particle-Containing Fiber Bundle]

[0121] One embodiment of the present invention relates to a method for manufacturing a particle-containing fiber bundle. The method for manufacturing a particle-containing fiber bundle includes mixing a plurality of short-sized fibers, particles having a median particle diameter of 100 μm or less, an organic binder, and a liquid to manufacture a particle-containing fiber bundle having an oblong spherical shape or a strand shape. In addition, the above fibers include carbon fibers, and 10 parts by mass or more of the above particles are used with respect to 100 parts by mass of the above fibers. It should be noted that the median particle diameter is defined as the particle diameter (D50) at which the cumulative value in the particle size distribution based on volume becomes 50%.

[0122] The method of using a plurality of short-sized fibers as starting materials typically includes the following steps (i) to (iii).

[0123] (i) Mixing step

[0124] (ii) Bundling step

[0125] (iii) Drying step

[0126] The timing of mixing the fibers, particles, organic binder, and liquid is not limited. From the viewpoint of manufacturing efficiency, it is preferably to include mixing the particles, organic binder, and liquid to obtain a mixture 1 and mixing the mixture 1 and the fibers to obtain a mixture 2. The mixture 1 can be prepared in the (i) mixing step or separately. The mixture 2 can be prepared in the (i) mixing step or can be bundled simultaneously with the generation of the mixture 2 in the (ii) bundling step. Regarding the usage amount of the raw materials, before generating the particle-containing fiber bundle, for example, the particles can be set to 10 to 200 parts by mass, the liquid can be set to 1 to 200 parts by mass, and the organic binder can be set to 1 to 40 parts by mass with respect to 100 parts by mass of the fibers.

[0127] From the viewpoint of maintaining the shape of the fiber bundle, the usage amount of the organic binder is preferably 1 part by mass or more, more preferably 3 part by mass or more, and further preferably 6 part by mass or more with respect to 100 parts by mass of the fibers. From the viewpoint of maintaining the shape of the particle-containing fiber bundle, the usage amount of the organic binder is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 10 parts by mass or less with respect to 100 parts by mass of the fibers. The above upper and lower limits can be arbitrarily combined. For example, it can be 1 to 40 parts by mass, it can be 3 to 20 parts by mass, or it can be 6 to 10 parts by mass.

[0128] From the viewpoint of reducing the total length of the particle-containing fiber bundle, the amount of particles used is 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, further preferably 40 parts by mass or more, particularly preferably 50 parts by mass or more, and most preferably 55 parts by mass or more, based on 100 parts by mass of the fiber. From the viewpoint of making the shape of the particle-containing fiber bundle uniform, the amount of particles used is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, further preferably 90 parts by mass or less, particularly preferably 80 parts by mass or less, and most preferably 75 parts by mass or less, based on 100 parts by mass of the fiber. The above upper and lower limits can be combined arbitrarily. For example, it can be 10 to 150 parts by mass, 20 to 150 parts by mass, 30 to 100 parts by mass, 40 to 90 parts by mass, 50 to 80 parts by mass, or 55 to 75 parts by mass.

[0129] From the viewpoint of uniformly dispersing the particles in the particle-containing fiber bundle, it is preferable to use the raw materials such that the mass ratio of the particles to the organic binder (mass of particles / mass of organic binder) is 2.5 to 100, and more preferably 5.0 to 50.

[0130] From the viewpoint of efficiently performing liquid bridging, the amount of liquid used is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 30 parts by mass or more, particularly preferably 60 parts by mass or more, and most preferably 80 parts by mass or more, based on 100 parts by mass of the fiber. From the viewpoint of facilitating drying, the amount of liquid used is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and further preferably 160 parts by mass or less, based on 100 parts by mass of the fiber. The above upper and lower limits can be combined arbitrarily. For example, it can be 5 to 200 parts by mass, 10 to 200 parts by mass, 30 to 180 parts by mass, 60 to 180 parts by mass, or 80 to 160 parts by mass.

[0131] The details of each process will be described below.

[0132] (i) Mixing process

[0133] In the mixing process, the fiber, particles, organic binder, and liquid can be mixed to obtain a mixture. In the mixing process, a general defibrator can be used, but there is no limitation. In one example, the fiber and particles can also be put into a stirring granulator such as a Henschel mixer and stirred and mixed in a dry state. This method has the following advantages: it is possible to enter the next bundling process without taking out the generated mixture from the stirring granulator. The mixing process can also be omitted and the bundling process can be carried out.

[0134] (ii) Bundling process

[0135] In the bundling step, a fiber bundle is formed by mixing the mixture obtained in the mixing step with a liquid. The particles, organic binder, and liquid may also be mixed separately in this step to prepare a mixture. From the viewpoint of making the particles and organic binder present inside the fiber bundle, the particles and organic binder are preferably mixed before the formation of the fiber bundle, that is, before the start of mixing in the bundling step or (i) in the mixing step.

[0136] The fibers and particles constituting the mixture are aggregated by capillary force based on the surface tension of the liquid to form a fiber bundle containing the liquid. It may also be used in the form of a mixed liquid obtained by mixing the liquid with the organic binder for bundling. Hereinafter, the liquid alone or the mixed liquid is referred to as the bundling liquid. There is no particular limitation on the bundling liquid. For example, a solvent such as an organic solvent may be used, and it may also contain an organic binder and other components. The organic binder and other components may be dissolved in the solvent, mechanically dispersed in the solvent, or dispersed in the solvent by a surfactant. In addition, as the bundling liquid, a bundling liquid whose viscosity is reduced by heating may be used.

[0137] With respect to 100 parts by mass of the total amount of the raw material fibers (hereinafter, sometimes referred to as "raw material fibers") used in the production of the particle-containing fiber bundle, the amount of the bundling liquid is, for example, 70 to 210 parts by mass, but is not limited. The amount of the bundling liquid can be appropriately adjusted while observing the state of the mixture.

[0138] If the viscosity of the bundling liquid is 10 Pa·s or less at 23°C, the shape of the particle-containing fiber bundle can be made uniform. The viscosity can be set to 8 Pa·s or less, 5 Pa·s or less, 2 Pa·s or less, 0.5 Pa·s or less. On the other hand, the viscosity can be set to 0.0001 Pa·s or more. The above upper and lower limits can be arbitrarily combined. For example, it can be 0.0001 to 10 Pa·s, 0.0001 to 8 Pa·s, 0.0001 to 5 Pa·s, 0.0001 to 2 Pa·s, or 0.0001 to 0.5 Pa·s.

[0139] When bundling is carried out by heating, a bundling liquid within the above viscosity range at the temperature at this time can be used. The viscosity is a value measured at a rotation speed of 50 rpm using a B-type rotational viscometer (for example, LVDV-1Pri manufactured by Brookfield).

[0140] If the surface tension of the bundling liquid is 120 mN / m or less, a liquid bridge can be formed between the fibers, making it easier for the fibers to move and enabling fiber orientation. The surface tension can be set to 110 mN / m or less, 100 mN / m or less, 90 mN / m or less, 72 mN / m or less, 60 mN / m or less, 50 mN / m or less, 40 mN / m or less at 23°C. On the other hand, the surface tension can be set to 10 mN / m or more, 15 mN / m or more, 20 mN / m or more, 30 mN / m or more. The above upper and lower limits can be arbitrarily combined. For example, it can be 10 - 120 mN / m, it can be 10 - 110 mN / m, it can be 15 - 100 mN / m, it can be 15 - 90 mN / m, it can be 20 - 72 mN / m, it can be 20 - 60 mN / m, it can be 30 - 50 mN / m, or it can be 30 - 40 mN / m.

[0141] The surface tension is a value measured by the plate method (vertical plate method). When bundling is carried out by heating, a bundling liquid within the above-mentioned tension range at the temperature at that time can be used.

[0142] As the degree of maintaining the fiber length, from the aspect of improving the uniformity of the fiber bundle, the ratio (Y / X) of the average fiber length Y of the fibers in the particle-containing fiber bundle to the average fiber length X of the raw material fibers is preferably 0.55 or more, more preferably 0.70 or more, further preferably 0.80 or more, and particularly preferably 0.90 or more. This ratio (Y / X) can be set to 1 or less. The above upper and lower limits can be arbitrarily combined. For example, it can be 0.55 - 1, it can be 0.70 - 1, it can be 0.80 - 1, or it can be 0.90 - 1.

[0143] Hereinafter, with reference to Figure 1A and Figure 1B a stirring granulator suitable for use in (i) the mixing process and (ii) the bundling process will be described.

[0144] As Figure 1A shown, it is preferable that the stirring granulator has a rotating shaft 2 on the central axis inside a bottomed cylindrical stirring tank 1, and multiple ([[]] Figure 1A in this case, 3) propeller-shaped stirring blades radially extend from the rotating shaft 2 at equal intervals. It can also be a disk-shaped stirring blade perpendicular to the rotating shaft. It can also be a disk with undulations and protrusions.

[0145] As Figure 1BAs shown, the stirring blade 3 is inclined with respect to the bottom surface 1A of the stirring tank 1 in the rotation direction. The angle θ between the surface 3A on the rear side with respect to the rotation direction R and the bottom surface 1A of the stirring tank 1 (hereinafter sometimes simply referred to as "inclination angle") is preferably in the range of 1 to 60°. If the inclination angle θ of the stirring blade 3 is 1° or more, the mixture can be stirred while circulating in the stirring tank. If the inclination angle θ of the stirring blade 3 is 60° or less, the rotational speed can be adjusted within the range of suppressing the resistance to the stirring blade without imposing a load on the device. The inclination angle θ is more preferably 10 to 50°, and further preferably 20 to 40°.

[0146] In Figure 1A it, the stirring blade 3 is bent at an angle α at approximately the middle in its length direction. For example, it can be configured such that the distance between the bottom surface of the stirring blade 3 and the bottom surface 1A of the stirring tank 1 is 1 mm or less to stir up the raw material staying at the bottom.

[0147] It can also be configured such that the distance between the front end of the stirring blade 3 and the side surface (wall surface) of the stirring tank 1 is 10 mm or more to suppress breakage caused by shearing of the raw material. The stirring blade is not limited to such a bent blade and can also be a straight plate-like blade. The stirring blade can also be bent into an arc shape.

[0148] In the stirring granulator, a propeller auxiliary stirring blade (chopper) for auxiliary stirring can be provided on the wall surface of the stirring tank. The stirring tank of the stirring granulator can be equipped with a scraper on the bottom surface or the side surface. The stirring tank uses a stirring tank having a stirring blade (agitator) rotating in the horizontal direction and a propeller auxiliary stirring blade (chopper) rotating in the vertical direction as the stirring blade. By using the stirring blade rotating in the horizontal direction and the propeller auxiliary stirring blade rotating in the vertical direction for stirring, efficient stirring granulation can be performed. The auxiliary stirring blade rotating in the vertical direction has the function of crushing over-sized granulated products and making the sizes of the particle-containing fiber bundles uniform.

[0149] The rotation condition of the stirring blade in the stirring granulator preferably makes the circumferential speed (hereinafter, simply referred to as "circumferential speed") of the front end of the stirring blade (part 3a in Fig. 1a) in the range of 1 to 20 m / s. If the circumferential speed is 1 m / s or more, the mixture can be stirred while circulating in the stirring tank. If the circumferential speed is 20 m / s or less, the particle shapes of the particle-containing fiber bundles can be made uniform. The circumferential speed of the stirring blade is more preferably 4 to 12 m / s, and further preferably 4 to 8 m / s.

[0150] The circumferential speed of the chopper is preferably set in the range of 5 to 30 m / s.

[0151] Hereinafter, refer to Figure 2Another mode of a stirring granulator suitable for a method of manufacturing a fibrous bundle containing particles will be described.

[0152] As Figure 2 shown, one mode of the rotating stirring granulator is configured with: a container 40 that houses raw material fibers, particles, an organic binder, and a liquid therein and is rotatable; and a rotating shaft portion 42 that is inside the container 40 and parallel to the central axis 41 at a position eccentric to the central axis 41 of the container 40. The rotating shaft portion 42 is preferably capable of rotating in a direction opposite to the rotating direction of the container 40. By rotating in the opposite direction, the impact force of the stirring blades on the raw material fibers increases, and the fibers can be aligned in a short time using strong shearing. The rotating direction of the rotating shaft portion 42 may also be the same as the direction of the container 40.

[0153] When the rotating direction of the stirring blades is the opposite direction to the rotating direction of the container, there is a tendency that the number of filaments contained in the fibrous bundle is small, and the distribution of the number of filaments and the shape contained in the fibrous bundle becomes uniform. When the rotating direction is the same as the rotating direction of the container, there is a tendency that the number of filaments contained in one fibrous bundle is large and the fibers tend to aggregate.

[0154] It is considered that if stirring is performed in such a way that the rotating direction of the stirring blades is the opposite direction to the rotating direction of the container, and then stirring is performed in such a way that the rotating direction of the stirring blades is the same as the rotating direction of the container, the liquid bridging between the fibrous bundles with a small number of filaments and a uniform distribution is promoted. Thereby, a fibrous bundle that is uniform and has a high volume density can be obtained.

[0155] The rotating shaft portion 42 has stirring blades 44 that extend near the bottom plate 43 of the container 40 and move within the region where the mixture can exist. By rotating the container 40, the mixture is circulated, and by rotating the stirring blades 44, shear is applied to the mixture, so that the fibers can be aligned. The blades of the stirring blades 44 can adopt the modes described in the stirring granulator. For example, it can be configured such that the distance between the bottom surface 49 of the stirring blade 44 and the bottom plate 43 of the stirring tank is 10 mm or more, so that the stirring blade can efficiently contact the raw material stirred up by the scraper. It can also be configured such that the distance between the tip 46 of the stirring blade 44 and the side surface 47 of the stirring tank is 10 mm or more, suppressing breakage caused by shearing of the raw material.

[0156] A scraper 45 is provided on the side surface of the container 40. A scraper may also be provided on the side surface 47, the bottom plate 43, or both inside the container 40. The attached raw material can be scraped off using the scraper 45.

[0157] Regarding the rotation conditions, the circumferential speed of the container 40 (container circumferential speed) can be set in the range of 0.4 to 1.2 m / s. If the circumferential speed is 0.4 m / s or more, the mixture can be stirred while circulating in the stirring tank. On the other hand, if the circumferential speed is 1.2 m / s or less, the mixture can be efficiently brought into contact with the stirring blades and the scraper, and the processing time can be shortened. The circumferential speed can be set to 0.5 to 1.0 m / s, 0.7 to 0.9 m / s.

[0158] The circumferential speed of the tip of the stirring blade 44 of the stirring blade (tip circumferential speed) can be set in the range of 1 to 30 m / s. If the tip circumferential speed is 1 m / s or more, the fibers can be aligned in a short time to increase the density of the fiber bundle. On the other hand, if the tip circumferential speed is 30 m / s or less, the shape of the fiber bundle can be made uniform. The circumferential speed of the stirring blade 44 can be set to 10 to 20 m / s, 1 to 8 m / s.

[0159] There is no particular limitation on the stirring time of the stirring granulator, and it is sufficient to stir for a time that can obtain the desired fiber bundle. By passing through the fiber cotton, the time taken for the bundling process can be shortened.

[0160] There is no particular limitation on the temperature during stirring, and it can be carried out at room temperature (for example, 5 to 40 °C). The temperature rise of the container and the mixture caused by the influence of stirring is allowed. When bundling, it can also be carried out at a temperature above the melting point or softening point of the organic binder, and after the formation of the particle-containing fiber bundle, it is cooled so that the organic binder becomes solid at the stage of maintaining the granulated product state.

[0161] Regarding the stirring conditions, it is preferably adjusted to obtain a fiber bundle in an aligned state, rather than adjusted to obtain a spherical carbon fiber ball with fiber curls. In order to obtain a fiber bundle in an aligned state, for example, methods such as increasing the amount of liquid, increasing the circumferential speed of the tip of the stirring blade, and using raw material fibers with an average fiber length greater than 1 mm can be cited.

[0162] There is no particular limitation on the end time of granulation, and it is preferably the time when it can be confirmed that a fiber bundle state is formed to the extent that the particle size distribution can be determined.

[0163] (iii) Drying process

[0164] In the drying process, the particle-containing fiber bundle formed in the bundling process is dried to remove the liquid contained in the bundling liquid contained in the particle-containing fiber bundle. Even if the liquid evaporates due to drying, the shape of the particle-containing fiber bundle can be maintained by the adhesion of the organic binder. The drying can be forced drying or natural drying.

[0165] In one example, it is possible to dry while stirring in a stirring tank without taking out the particle-containing fiber bundle formed in the stirring tank of the stirring granulator from the stirring tank.

[0166] In another example, it is also possible to take out the particle-containing fiber bundle formed in the stirring tank of the stirring granulator from the stirring tank and dry it at other places. Other places can be, for example, a hot air dryer, or it can also be in a conveying pipe or on a conveyor belt.

[0167] When using a dryer, it can be carried out at 50 to 150 °C for about 1 to 5 hours.

[0168] As drying equipment, for example, a box dryer, a conveyor belt dryer, a tunnel dryer, a fixed tank stirring dryer, a drum rotary dryer, a rotary furnace, a fluidized bed dryer, a stirring hot air dryer, a pneumatic dryer, an infrared dryer, a microwave dryer, a vacuum dryer can be cited.

[0169] As other processes, a classification process and a cutting process can also be passed through.

[0170] The classification process can be introduced in any of the processes (i) to (iii), but by introducing it after (iii), the uniformity of multiple particle-containing fiber bundles can be improved.

[0171] The sieve for classification can be set, for example, to a configuration including a vibration mechanism, a container combined with the vibration mechanism, and a sieve mesh that divides the internal space of the container. For the sieve mesh, the mesh shape and the sieve hole size are adjusted so that the particle-containing fiber bundle can be sieved into a desired size.

[0172] When the particle-containing fiber bundle is in an oblate spheroid shape, the mesh shape is preferably rectangular or rhombic. The mesh shape can also be square or circular.

[0173] The cutting process is preferably introduced before (i). For example, a continuous fiber bundle composed of virgin fibers is cut at a predetermined interval in the fiber direction using a rotary cutter to produce a cut fiber bundle.

[0174] The bundle size of the continuous fiber bundle (the number of fiber filaments constituting the bundle) can be set, for example, to 10K or more and 100K or less. Here, "K" is a symbol representing 1000. For example, 1K means 1000, and 10K means 10000. From the viewpoint of production efficiency, the bundle size of the continuous fiber bundle is preferably 24K or more, more preferably 36K or more, and further preferably 48K or more. For example, it can be 24K or more and 100K or less, it can be 36K or more and 100K or less, or it can be 48K or more and 100K or less.

[0175] The fiber length of the chopped fiber bundle is not limited. For example, it is 3 mm or more, and can also be 5 mm or more or 10 mm or more. Additionally, for example, it is 60 mm or less, and can also be 50 mm or less, 40 mm or less, 30 mm or less, or 20 mm or less. The above upper and lower limits can be combined arbitrarily. For example, it can be 3 - 60 mm, can be 3 - 50 mm, can be 5 - 40 mm, can be 5 - 30 mm, or can also be 10 - 20 mm.

[0176] When the chopped fiber bundle contains water, sizing agent, etc., it is preferable to remove the water, sizing agent, etc. by solvent or thermal decomposition to produce a dry fiber cotton.

[0177] <Fiber>

[0178] The raw material fiber uses multiple fibers that have been short-sized, and it is preferable to use a fiber cotton containing multiple short-sized fibers. By using fiber cotton, bundling can be carried out from the state of being separated into single filaments, so it is easy to efficiently obtain a uniform particle-containing fiber bundle.

[0179] The fiber contains carbon fiber. Carbon fiber is useful in manufacturing a fiber-reinforced resin composition and can provide a fiber-reinforced resin composition with high specific strength and specific modulus of elasticity. As the carbon fiber, there are PAN-based and pitch-based types, and PAN-based is easier to obtain. From the perspective of specific strength and specific modulus of elasticity, the proportion of carbon fiber in the raw material fiber is preferably 70% by mass or more, and more preferably 90 - 100% by mass.

[0180] The raw material fiber is not limited to virgin fiber and can also be recycled fiber. Figure 3 It is an example of the form of recycled fiber. The recycled fiber is a fiber cotton formed by randomly overlapping single filaments. Figure 4 It is an example of the form of virgin fiber. The virgin fiber is a fiber bundle mass with fibers aligned.

[0181] A sizing agent and the matrix resin of FRP can also be attached to the raw material fiber. The resin residue amount of raw material fibers such as carbon fiber is, for example, in the range of 0.01 - 10%.

[0182] Through the manufacturing method of the particle-containing fiber bundle described above, even if the raw material fiber contains recycled fiber, the fiber will not be cut, and the fibers will be aligned while maintaining the length, and a particle-containing fiber bundle with controlled dimensions can be manufactured. As the recycled fiber, fibers obtained by decomposing the matrix using heat, subcritical fluid, or supercritical fluid, fibers obtained by cutting the end material of the fiber substrate, etc. can be cited. The recycled fiber can completely remove the matrix until it becomes cotton-like. In the case where there is resin residue that has not been completely removed, it can be removed by heat treatment in an oxidizing atmosphere.

[0183] The fibers contained in the particle-containing fiber bundle can be fibers that have undergone thermal deterioration in part or in whole. Examples of carbon fibers that have undergone thermal deterioration are recycled carbon fibers recovered from waste CFRP, which have undergone thermal deterioration during the process of thermally decomposing and removing the matrix resin.

[0184] The raw material fibers are formed by aggregating multiple short-sized fibers (discontinuous fibers), and are preferably cotton-like. By being cotton-like, they are separated into single filaments in the dry state, so that when wetted and a certain orientation is formed on the fibers, the energy for eliminating the orientation is not required, and the size control of the particle-containing fiber bundle can be efficiently performed.

[0185] The raw material fibers may contain aligned fiber groups, but preferably, for example, 50% by mass or more of the raw material fibers is fiber cotton.

[0186] The short-sized fibers can be obtained by cutting a continuous fiber bundle, or fibers in a discontinuous form can also be used.

[0187] The continuous fibers can be a tow or fibers taken out from a prepreg, a molded body, etc. For example, recycled fibers obtained by thermally decomposing the matrix are in the state of dry cotton-like fibers just after heating. By using a stirring granulator, a particle-containing fiber bundle with aligned fibers can be obtained without changing the fiber morphology in the fiber regeneration process.

[0188] The raw material fibers can be defibrated before stirring with a stirring granulator or the like. For example, before introducing the fiber treatment agent into the stirring tank, the fiber without liquid is stirred in the stirring tank by the stirring blades, thereby defibrating the raw material fibers. By using the action of the rotation of the stirring blades to untie the fibers bonded by attachments such as resin carbide into smaller unit fibers, the fibers can be easily aligned by the stirring of the stirring blades after adding the fiber treatment agent. At the same time, the uniformity of the fiber bundle can be improved.

[0189] There is no particular limitation on the fiber diameter of the raw material fibers. For example, it is in the range of 3 μm to 100 μm, and it is easy to obtain 5 μm to 15 μm.

[0190] The bulk density of the raw material fibers is, for example, in the range of 0.01 to 0.90 g / cm 3 If the bulk density of the raw material fibers is in the range of 0.01 to 0.10 g / cm 3 , it is easy to convert it into a fiber bundle with a bulk density greater than that of the raw material fibers. For example, fiber cotton can be cited for fibers in the range of 0.01 to 0.10 g / cm 3 .

[0191] From the viewpoint of uniform bundling, the fiber length of the raw material fibers is preferably 100 mm or less, more preferably 60 mm or less, still more preferably 50 mm or less, and may be 20 mm or less, 12 mm or less.

[0192] From the viewpoint of the strength when used in a molded body, the fiber length of the fiber bundle containing particles is preferably 1 mm or more, more preferably 2 mm or more.

[0193] The fibers may not contain fibers having a fiber length of less than 1 mm, or may contain them in an amount of less than 5 wt%.

[0194] When used in a fiber-reinforced resin composition (granules) for extrusion molding, the average fiber length of the raw material fibers is preferably 2 to 12 mm.

[0195] When used in a fiber-reinforced resin material (prepreg) for compression molding, the average fiber length of the raw material fibers is preferably 12 to 50 mm, and more preferably 12 to 30 mm from the viewpoint of facilitating the dispersion and uniform stacking of the fiber bundle containing particles when manufacturing the prepreg.

[0196] If the fiber length of the raw material fibers is above the above lower limit, the strength of the fiber-reinforced resin composition can be sufficiently improved, and the fiber orientation can be highly controlled. If the average fiber length of the raw material fibers is below the above upper limit, winding around the device during the production of the fiber bundle containing particles can be suppressed, the production efficiency can be improved, and the shape of the fiber bundle containing particles can be uniformly controlled.

[0197] The average fiber length is the weighted average fiber length. The average fiber length can be measured by the method described in the following Examples. It is also possible to binarize the image taken by microscopic observation using image processing software such as ImageJ and calculate the average fiber length.

[0198] By forming the fiber bundle containing particles only from fibers having the same fiber length, quality variations of the fiber bundles containing particles between production batches can be suppressed. Among the plurality of short-sized fibers constituting the fiber bundle containing particles, the difference between the maximum value and the minimum value of the fiber length is preferably within 5 mm, more preferably within 4 mm, still more preferably within 3 mm.

[0199] <Particles>

[0200] By using particles having a median particle size of 100 μm or less, the shape of the fiber bundle containing particles can be made uniform while adjusting the total length of the fiber bundle containing particles to be shorter. The shorter the total length of the fiber bundle containing particles, the less the fiber interference at the front ends of the fiber bundles containing particles, and it is easy to improve the feeding efficiency from the hopper to the feeder. By the presence of particles in the fiber bundle containing particles, a space can be formed between the fibers, making it easier for the resin to be impregnated.

[0201] It should be noted that in this specification, the solubility of the particles in water at 23°C is 0.0001 g / mL or less, and it is a material used separately from the organic binder described in the <organic binder> described later.

[0202] In addition, the particles are preferably particles that can maintain their shape in the presence and absence of the liquid component described in the <liquid> described later.

[0203] From the viewpoint of adjusting to shorten the total length of the particle-containing fiber bundle, it is preferable that the particles are not easily soluble in the liquid described later. For example, by setting the solubility in the liquid at 23°C to 0.01 g / 100 g or less, the particles can enter the fiber bundle in a state where their shape is maintained during mixing.

[0204] The median particle size of the particles is the particle size (D50) at which the cumulative value in the volume-based particle size distribution becomes 50%. It is preferably 0.1 μm or more, more preferably 3 μm or more, and further preferably 10 μm or more. Thereby, the total length of the particle-containing fiber bundle can be adjusted to be shortened. In addition, during injection molding and compression molding of the obtained particle-containing fiber bundle, the fibers are easily unraveled and uniformly dispersed, and the appearance of the molded product becomes good. The median particle size of the particles is preferably 90 μm or less, more preferably 80 μm or less, and further preferably 60 μm or less. Thereby, the shape of the particle-containing fiber bundle can be made uniform. In addition, during injection molding and compression molding of the obtained particle-containing fiber bundle, the interface between the fiber bundles becomes uniform, and the strength of the molded product is improved.

[0205] The above upper and lower limits can be arbitrarily combined. For example, it can be 0.1 to 90 μm, it can be 3 to 80 μm, or it can be 10 to 60 μm.

[0206] The particle size D90 at which the cumulative value in the volume-based particle size distribution of the particles becomes 90% is preferably 350 μm or less, more preferably 250 μm or less, and further preferably 100 μm or less. Thereby, the distribution of the particles and the fibers inside the particle-containing fiber bundle becomes uniform. In addition, during injection molding and compression molding of the obtained particle-containing fiber bundle, the fibers are easily unraveled and uniformly dispersed, and the appearance of the molded product becomes good. The particle size D90 is preferably 0.5 μm or more, more preferably 30 μm or more. The total length of the particle-containing fiber bundle can be adjusted to be shortened. In addition, during injection molding and compression molding of the obtained particle-containing fiber bundle, the fibers are easily unraveled and uniformly dispersed, and the appearance of the molded product becomes good.

[0207] The above upper and lower limits can be arbitrarily combined. For example, it can be 0.5 to 350 μm, it can be 0.5 to 250 μm, or it can be 30 to 100 μm.

[0208] The particle size D10 at which the cumulative value in the volume-based particle size distribution of the particles becomes 10% is preferably 70 μm or less, more preferably 50 μm or less, and still more preferably 30 μm or less. Thereby, the distribution of the particles and fibers inside the particle-containing fiber bundle can be made uniform. In addition, during injection molding or compression molding of the obtained particle-containing fiber bundle, the interfaces between the fiber bundles become uniform, and the strength of the molded product is improved. The particle size D10 is preferably 0.05 μm or more, more preferably 1 μm or more. Thereby, the total length of the particle-containing fiber bundle can be adjusted to be shorter. In addition, during injection molding or compression molding of the obtained particle-containing fiber bundle, the fibers are easily unraveled and uniformly dispersed, and the appearance of the molded product becomes good.

[0209] The above upper and lower limits can be combined arbitrarily. For example, it can be 0.05 - 70 μm, it can be 0.05 - 50 μm, or it can be 1 - 30 μm.

[0210] The ratio (D75 / D25) of the particle size D75 at which the cumulative value in the volume-based particle size distribution of the particles becomes 75% to the particle size D25 at which it becomes 25% is preferably 1 - 15, more preferably 1 - 10. Thereby, the distribution of the particles and fibers inside the particle-containing fiber bundle can be made uniform. In addition, during injection molding or compression molding of the obtained particle-containing fiber bundle, the interfaces between the fiber bundles become uniform, and the strength of the molded product is improved.

[0211] The relationship formula (D84 - D16) / 2 between the particle size D84 at which the cumulative value in the volume-based particle size distribution of the particles becomes 84% and the particle size D16 at which it becomes 16% can be set to 1 - 150, 5 - 100.

[0212] The volume-based particle size distribution of the particles can be obtained by laser diffraction scattering method or image analysis. The measurement of the particle size distribution using the laser diffraction scattering method can be carried out, for example, by the method described in the examples. In addition, the measurement of the particle size distribution based on image analysis can be carried out, for example, by obtaining the particle sizes of 50 or more particles from the image obtained using an optical microscope.

[0213] When using a commercially available product as the particles, the median particle size, D90, D10, D75, D25, D84, D16 of the catalog value can be used.

[0214] It should be noted that two or more kinds of particles with different particle sizes can also be used, that is, particles having two or more peaks with different particle sizes in the particle size distribution measured by the above method. When using particles having a peak at 1000 μm or more in particle size, based on the particle size distribution obtained by separating the peak at 1000 μm or more by peak separation, the median particle size, D90, D10, D75, D25, D84, D16 are obtained.

[0215] The ratio of the average fiber length of the raw material fibers to the median particle size (average fiber length of the raw material fibers (μm) / median particle size of the particles (μm)) is preferably 10 to 150, more preferably 30 to 130. Thereby, the total length of the particle-containing fiber bundle can be adjusted to be shorter. In addition, during injection molding or compression molding of the obtained particle-containing fiber bundle, the fibers are easily unraveled and uniformly dispersed, and the appearance of the molded product becomes good. The ratio of the average fiber diameter of the raw material fibers to the median particle size (average fiber diameter of the raw material fibers (μm) / median particle size of the particles (μm)) is preferably 0.01 to 0.4, more preferably 0.07 to 0.3. Thereby, the distribution of the particles and the fibers inside the particle-containing fiber bundle can be made uniform. In addition, during injection molding or compression molding of the obtained particle-containing fiber bundle, the interface between the fiber bundles becomes uniform, and the strength of the molded product is improved.

[0216] Examples of the shape of the particles include spherical, flat, needle-shaped, amorphous, etc. However, a shape different from that of the fibers is more likely to shorten the total length of the particle-containing fiber bundle. Therefore, a spherical shape is preferred. In addition, by making it spherical, during injection molding or compression molding, the fibers are easily unraveled and uniformly dispersed, and the appearance of the molded product becomes good. The aspect ratio of the particles can be set to 1 to 1.5.

[0217] The maximum Feret diameter of the particles can be set to 0.1 μm to 100 μm, or can also be set to 3 to 80 μm. Regarding the maximum Feret diameter, analyze more than 50 particles from the image obtained using a transmission electron microscope (TEM). Thus, the median value of the maximum distance between parallel tangents that are in contact with the relative contour lines can be used.

[0218] Examples of the types of particles include organic particles and inorganic particles. Examples of organic particles include thermoplastic resin particles, thermosetting resin particles, curing agent particles, etc. Curing agent particles can be obtained by curing a thermosetting resin. Thermoplastic resin particles and thermosetting resin particles can be components of the matrix resin constituting the fiber-reinforced resin composition or its molded body. It should be noted that organic particles and inorganic particles can be used in combination.

[0219] Examples of the resin constituting the thermoplastic resin particles include polyamide resin, polyolefin resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyetheretherketone resin, polyetherimide resin, and polyphenylene sulfide resin.

[0220] When used as the matrix resin of the fiber-reinforced resin composition, from the viewpoint of the impact resistance of the molded body, polyamide resin, polyetheretherketone resin, polyetherimide resin, or polyphenylene sulfide resin is preferred.

[0221] Particularly in the case of using polyetheretherketone resin particles, even a polyetheretherketone resin with high viscosity, which is difficult to impregnate for example, can be impregnated into the fibers, thus improving the mechanical properties of the molded product.

[0222] The thermoplastic resin particles are used in an amount of, for example, 1 to 200 parts by mass with respect to 100 parts by mass of the total amount of the raw fibers. However, in the case of directly using the obtained fiber bundle containing particles as a molding material, it is preferably 30 to 300 parts by mass, and in the case of converting the fiber bundle containing particles into other molding materials, it is preferably 1 to 100 parts by mass.

[0223] Examples of the resin constituting the thermosetting resin particles include epoxy resin, vinyl ester resin, unsaturated polyester resin, cyanate resin, polyimide resin, maleimide resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane resin, and phenolic resin.

[0224] When used as the matrix resin of the fiber-reinforced resin composition, from the viewpoint of the strength of the cured product, epoxy resin, vinyl ester resin, cyanate resin, or phenolic resin is preferred.

[0225] The thermosetting resin particles are used in an amount of, for example, 1 to 200 parts by mass with respect to 100 parts by mass of the total amount of the raw fibers. In the case of directly using the obtained fiber bundle containing particles as a molding material, it is preferably 30 to 300 parts by mass, and in the case of converting the fiber bundle containing particles into other molding materials, it is preferably 1 to 100 parts by mass.

[0226] Examples of the curing agent particles include dicyandiamide-based, phenol-based, amine-based, carboxylic anhydride-based, mercaptan-based, imidazole-based, phosphine-based, peroxide-based, and organic metal salt-based.

[0227] The curing agent particles are used in an amount of, for example, 1 to 100 parts by mass with respect to 100 parts by mass of the total amount of the raw fibers. However, from the viewpoint of reducing the remaining amount so as not to become the starting point of the destruction of the molded body, it is preferably 2 to 10 parts by mass.

[0228] Examples of the inorganic particles include metal particles, metal oxide particles, silica particles, silicate particles, carbonate particles, sulfate particles, hydroxide particles, glass particles, ceramic particles, graphite, and carbon black.

[0229] The inorganic particles are used in an amount of, for example, 1 to 200 parts by mass with respect to 100 parts by mass of the total amount of the raw fibers. However, from the viewpoint of reducing the remaining amount so as not to become the starting point of the destruction of the molded body, it is preferably 2 to 150 parts by mass.

[0230] These particles can be used alone or in combination of two or more.

[0231] <Organic Binder>

[0232] The organic binder is not particularly limited as long as it is an organic substance capable of bonding fibers to each other. Preferred examples of the material of the organic binder are resins used for sizing in commercially available general fiber bundles. In other words, it can also be called the component resin of the sizing agent. Examples of such resins include polyamide resins, epoxy resins, unsaturated polyester resins, vinyl ester resins, and polyurethane resins, but are not limited to these. These resins can be used alone as one kind, or two or more kinds can be used in combination.

[0233] The organic binder may contain the same resin as the resin constituting the particles, but is used separately from the particles in order to bond the fibers to each other.

[0234] It should be noted that generally, the solubility of the organic binder in water at 23°C is greater than 0.0001 g / mL. Additionally, generally, the solubility of the organic binder in a liquid at 23°C is greater than 0.01 g / mL.

[0235] In addition to the above resins, a surfactant can be blended in the organic binder. As the surfactant, for example, anionic surfactants such as alkyl ether carboxylates, cationic surfactants such as aliphatic quaternary ammonium salts and imidazolinium salts, amphoteric surfactants such as carboxybetaine type, and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene glycerol fatty acid esters, and polyethylene glycol fatty acid esters can be cited.

[0236] <Liquid>

[0237] By using a liquid, a liquid bridge between the fibers can be formed to perform bundling. From the viewpoint of being able to form a liquid bridge between the fibers at room temperature, it is preferably a liquid at room temperature (25°C).

[0238] As the liquid, alcohols such as methanol, ethanol, and propanol; ketones such as acetone and methyl ethyl ketone; hydrocarbon solvents such as hexane, cyclohexane, benzene, toluene, and styrene, and water can be cited. From the viewpoint of not requiring explosion-proof equipment during the manufacturing process, water is preferred.

[0239] [Fiber Bundle Containing Particles]

[0240] Another embodiment of the present invention relates to a fiber bundle containing particles.

[0241] A fiber bundle containing particles according to one embodiment of the present invention includes a plurality of short-sized fibers, particles having a median particle size of 100 μm or less, and an organic binder, and has an oblong spherical shape or a strand shape. Additionally, the above fibers include carbon fibers, and 10 parts by mass or more of the above particles are contained relative to 100 parts by mass of the fibers.

[0242] Another embodiment of the particle-containing fiber bundle of the present invention includes a plurality of short-sized fibers, polyether ether ketone resin particles, and an organic binder, and has an oblong spherical shape or a strand shape.

[0243] The fibers in the particle-containing fiber bundle are preferably aligned to form a fiber bundle. In addition, the fibers present on the surface of the fiber bundle are preferably bent and oriented along the contour of the oblong spherical shape.

[0244] The particle-containing fiber bundle can be manufactured, for example, by the manufacturing method of the particle-containing fiber bundle described above. According to the manufacturing method of the particle-containing fiber bundle, since the fiber bundle is formed by the aggregation of a plurality of fibers, the front-end positions of the fibers constituting the particle-containing fiber bundle do not coincide.

[0245] From the viewpoint of the feeding efficiency to the kneader, the shape of the particle-containing fiber bundle for use as a raw material for injection molding and granulation is preferably an oblong spherical shape.

[0246] From the viewpoint of the strength when forming a molded body, the shape of the fiber bundle for use in SMC is preferably a strand shape. The longer the fiber length of the fibers contained in the particle-containing fiber bundle, the easier it is to form a strand shape.

[0247] Figures 5 - 7 The appearance and cross-section of the particle-containing fiber bundle obtained in the following-described examples are shown. In one example, the particle-containing fiber bundle has Figure 5 an oblong spherical shape with the fibers aligned as shown in Figure 6 and Figure 7 shown, and the particles and fibers are uniformly present on the surface (appearance) and inside (cross-section) of the particle-containing fiber bundle.

[0248] The length of the particle-containing fiber bundle can be 3 mm or more, 6 mm or more, 12 mm or more, 20 mm or more, 50 mm or more, 70 mm or more. The length of the particle-containing fiber bundle can be 100 mm or less, 70 mm or less, 50 mm or less, 40 mm or less, 25 mm or less, 12 mm or less, 6 mm or less. The above upper and lower limits can be arbitrarily combined. For example, it can be 3 to 100 mm, it can be 6 to 70 mm, it can be 12 to 50 mm, it can be 20 to 40 mm, it can be 50 to 100 mm, it can be 70 to 100 mm, it can be 3 to 25 mm, it can be 3 to 12 mm, or it can be 3 to 6 mm.

[0249] The length of the particle-containing fiber bundle can be determined by the method described in the examples.

[0250] When the particle-containing fiber bundle is used as a raw material for injection molding and granulation, the length of the particle-containing fiber bundle is preferably 3 mm to 12 mm.

[0251] When using the particle-containing fiber bundle as a raw material for compression molding or SMC, the length of the particle-containing fiber bundle is preferably 12 mm or more and 50 mm or less.

[0252] The diameter of the thickest part of the particle-containing fiber bundle can be set to 0.1 mm to 10 mm, and the cross-sectional shape can be, for example, circular or elliptical.

[0253] From the viewpoint of the strength when forming a molded body, it is preferable that the length of the particle-containing fiber bundle is longer than the average fiber length of the fibers in the particle-containing fiber bundle.

[0254] From the viewpoint of feeding efficiency, the ratio of the length of the particle-containing fiber bundle to the average fiber length of the fibers contained in the particle-containing fiber bundle (length of the particle-containing fiber bundle / average fiber length of the fibers contained in the particle-containing fiber bundle) is preferably 1.1 to 5.0. In particular, when the feeder is a screw feeder equipped with a hopper, from the aspect of easily stably supplying a certain amount without clogging the supply port, it is more preferably 1.1 to 2.5.

[0255] When the particle-containing fiber bundle is in an oblong spherical shape, the diameter of the thickest part is preferably 2 mm to 7 mm.

[0256] In addition, the length of the major axis of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the fiber bundle, and is preferably 3 mm to 18 mm. This ratio (length of the major axis of the particle-containing fiber bundle / average fiber length of the fibers contained in the fiber bundle) is preferably 1.1 to 5.0.

[0257] When the shape of the particle-containing fiber bundle for SMC is a strand shape, the diameter of the thickest part is preferably 2 mm to 10 mm.

[0258] In addition, the length of the major axis of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the particle-containing fiber bundle, and is preferably 12 mm to 150 mm. This ratio (length of the major axis of the particle-containing fiber bundle / average fiber length of the fibers contained in the particle-containing fiber bundle) is preferably 1.1 to 3.0.

[0259] The fibers contained in the particle-containing fiber bundle function as a reinforcing material for the molded body.

[0260] The number of filaments contained in the particle-containing fiber bundle can be, for example, 8000 or more and 800000 or less.

[0261] By having more filaments in the central part of the major axis of the particle-containing fiber bundle than at the end part of the major axis, an oblong spherical shape can be formed.

[0262] Among all the fibers contained in the particle-containing fiber bundle, from the viewpoint of fluidity during molding, the fiber length is preferably 60 mm or less, more preferably 40 mm or less, further preferably 30 mm or less, and may also be 20 mm or less, 12 mm or less. From the viewpoint of strength when used in a molded article, the fiber length of the fiber contained in the particle-containing fiber bundle is preferably 1 mm or more, more preferably 2 mm or more. The fiber may not contain fibers with a fiber length less than 1 mm, or may contain them in an amount less than 5 wt%.

[0263] The above upper and lower limits can be arbitrarily combined. For example, it can be 1 to 60 mm, 1 to 40 mm, 1 to 30 mm, 2 to 20 mm, or 2 to 12 mm.

[0264] From the viewpoint of uniform bundling, the average fiber length is preferably 1 to 80 mm, more preferably 2 to 50 mm.

[0265] When used in a fiber-reinforced resin composition (granules) for extrusion molding, the average fiber length of the fiber is preferably 2 to 12 mm.

[0266] When used in a fiber-reinforced resin composition (prepreg) for compression molding, the average fiber length of the fiber is preferably 12 to 50 mm.

[0267] The average fiber length is the weighted average fiber length. It is also possible to use image processing software such as imageJ to perform binarization processing on the images taken by microscopic observation and calculate the fiber length.

[0268] By forming the particle-containing fiber bundle only from fibers having the same fiber length, it is possible to suppress the quality deviation of the particle-containing fiber bundle between manufacturing batches.

[0269] Among the multiple fibers constituting the particle-containing fiber bundle, the difference between the maximum value and the minimum value of the fiber length is preferably within 5 mm, more preferably within 4 mm, and further preferably within 3 mm.

[0270] The volume density of the particle-containing fiber bundle can be set, for example, to 0.03 to 0.7 g / cm 3 . It varies depending on the raw material fiber used, but from the viewpoint of the conveying efficiency of the particle-containing fiber bundle, the volume density is preferably 0.1 g / cm 3 or more, particularly preferably 0.2 g / cm 3 or more. If it is for the use of a molded article with a small fiber content, the volume density can be set to 0.1 g / cm 3 or more and less than 0.3 g / cm 3 . If it is for the use of a molded article that requires strength, the volume density can be set to 0.3 g / cm 3~0.6 g / cm 3 From the aspect of being able to increase the amount of material that can be fed at one time, in any case, the bulk density is preferably 0.15 g / cm 3 or more, particularly preferably 0.2 g / cm 3 or more.

[0271] The bulk density of the particle-containing fiber bundle is measured in accordance with JIS Z2512 and JIS R1628.

[0272] The angle of repose of the particle-containing fiber bundle is preferably 60° or less, more preferably 50° or less. The angle of repose of the particle-containing fiber bundle can be set to 10° or more. For example, it can be 10 to 60°, or it can be 10 to 50°.

[0273] The angle of repose of the particle-containing fiber bundle can be obtained as follows: Let 200 g of the fiber bundle fall naturally from a position 100 mm in height onto a horizontal circular plate, measure the accumulated height of the fiber bundle after 10 seconds, set the radius of the circular plate as R, set the accumulated height as T, and obtain the angle of repose θ = tan-1(T / R).

[0274] As the type of fiber, the fibers described in the above <Fiber> can be applied. From the viewpoints of specific strength and specific elastic modulus, the mass content ratio of carbon fiber in all the fibers in the particle-containing fiber bundle is preferably 70 mass% or more, more preferably 70 to 100 mass%, and further preferably 90 to 100 mass%.

[0275] As the particles, the particles described in the above <Particles> can be applied. By containing particles, it is possible to endow the molding material and the molded body with functions derived from the particles, and it is easy for the matrix resin to impregnate the fibers during the manufacture of the molding material or during molding. The particle size distribution of the particles in the particle-containing fiber bundle can be measured as follows: After washing the particle-containing fiber bundle with a solvent that can dissolve the organic binder, separate the fibers and the particles by filtration, etc., and use the method described in the above <Particles> for measurement.

[0276] As the organic binder, the organic binders described in the above <Organic Binder> can be applied. By containing the organic binder, it is possible to bond the fibers to each other and maintain the manufacturing shape of the particle-containing fiber bundle.

[0277] In addition, the particle-containing fiber bundle can contain fillers such as silica, calcium silicate, alumina, calcium carbonate, talc, barium sulfate; flame retardants such as metal hypophosphites, aluminum hydroxide, magnesium hydroxide; mold release agents such as silicone oil, wetting and dispersing agents, defoaming agents, degassing agents, natural waxes, synthetic waxes, metal salts of linear fatty acids, amides, esters, paraffins.

[0278] The mass content rate of the fibers in the particle-containing fiber bundle can be set to, for example, 10 to 99% by mass. The volume content rate of the fibers in the particle-containing fiber bundle can be set to, for example, 7 to 99% by volume.

[0279] In the case of using it for manufacturing particles, the mass content rate of the fibers in the particle-containing fiber bundle can be set to, for example, 80 to 99% by mass.

[0280] In the case of directly putting the particle-containing fiber bundle into a molding die or the like for molding, the mass content rate of the fibers in the particle-containing fiber bundle can be set to, for example, 10 to 70% by mass.

[0281] The mass content rate of the whole particles in the particle-containing fiber bundle can be set to, for example, 20 to 80% by mass, and from the viewpoints of moldability and imparting functions, it is preferably 30 to 70% by mass.

[0282] In the case of thermoplastic resin particles or thermosetting resin particles, it can be set to 20 to 80% by mass.

[0283] In the case of curing agent particles or inorganic particles, it can be set to 1 to 70% by mass.

[0284] The mass content rate of the organic binder in the particle-containing fiber bundle can be set to, for example, 0.1 to 90% by mass, and from the viewpoint of maintaining the shape of the fiber bundle, it is preferably 0.5 to 20% by mass.

[0285] The mass content rate of the liquid in the particle-containing fiber bundle can be set to, for example, 5% by mass or less, 1% by mass or less, and it can also be dried so that the particle-containing fiber bundle does not contain liquid.

[0286] From the viewpoint of being used as a molding material, the moisture content rate (mass) of the particle-containing fiber bundle is preferably 5% by mass or less, 1% by mass or less.

[0287] From the viewpoint of uniformly dispersing the particles in the particle-containing fiber bundle, the mass ratio of the particles to the organic binder in the particle-containing fiber bundle (mass of particles / mass of organic binder) is preferably 2.5 to 100, and more preferably 5 to 50.

[0288] [Use]

[0289] The particle-containing fiber bundle manufactured by the manufacturing method of the particle-containing fiber bundle described above can be used as a reinforcing fiber for various prepregs (random, unidirectional), particles, stamping sheets and other fiber-reinforced resin compositions and molding materials.

[0290] In the case of using the particle-containing fiber bundle as an intermediate material for molding, a molded body formed by fusing a plurality of particle-containing fiber bundles with each other can be made.

[0291] When using organic particles as the matrix resin material, adjacent particle-containing fiber bundles can be fused to each other by melting the organic particles.

[0292] When an organic particle is contained as an additive, adjacent particle-containing fiber bundles can be fused to each other by melting or reacting the organic binder. From the aspect of being able to adjust the fiber content as a reinforcing material, a thermoplastic resin or a thermosetting resin can also be added during fusion for supplementation. For example, a molded body can be obtained by dispersing a plurality of particle-containing fiber bundles in a mold and performing compression molding. It is also possible to heat the particle-containing fiber bundles in a state without applying pressure using an oven or the like to cause fusion.

[0293] When using a particle-containing fiber bundle as the fiber material contained in the particles, particles can be manufactured by melt-kneading a plurality of particle-containing fiber bundles.

[0294] As a method for manufacturing particles, for example, there can be mentioned: a method of directly melt-kneading a plurality of particle-containing fiber bundles without adding other components such as resins; a method of dry-mixing a thermoplastic resin and a particle-containing fiber bundle and then performing melt-kneading; a method of supplying a particle-containing fiber bundle to a molten thermoplastic resin and performing kneading.

[0295] A single-screw extruder, a twin-screw extruder, or the like is used for melt-kneading. It has the following advantages: when feeding the particle-containing fiber bundle from the hopper to the kneading area by putting the particle-containing fiber bundle described above into the hopper installed in the extruder, fiber bridging can be suppressed.

[0296] The particle-containing fiber bundle can also be directly used as a raw material for injection molding like the particles.

[0297] Examples

[0298] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited by any of the following examples.

[0299] [Measurement and Evaluation Methods]

[0300] Various measurement and evaluation methods are as described below.

[0301] <Particle Size Distribution>

[0302] The particle size distribution of the particles is measured by suspending 0.1 g of the particles in 10 mL of an aqueous solution containing 0.1 mass% of a surfactant, dropping it into a laser diffraction / scattering type particle size distribution measuring device (Horiba, Ltd.: LA-960V2, wet measurement, water solvent) so that the transmittance falls within the range of 65% to 95%, and irradiating ultrasonic waves for 1 minute.

[0303] <Surface Tension>

[0304] The surface tension of the bundling liquid at 23 °C was measured using an automatic surface tensiometer (Kyowa Interface Science: CBVP-A3, plate method).

[0305] <Viscosity>

[0306] The viscosity of the bundling liquid at 23 °C was measured using a B-type rotational viscometer (Brookfield: LVDV-1Pri, spindle S61) at a rotational speed of 50 rpm.

[0307] <Length of fiber bundle>

[0308] The fiber bundle was placed on a white board, and the image obtained by photographing from the vertical direction opposite to the white board was binarized using image analysis software, ImageJ (Wayne Rasband), and the Feret diameter of the fiber bundle was measured. The Feret diameters of 60 or more fiber bundles were averaged to obtain the length of the fiber bundle.

[0309] <Standard deviation and coefficient of variation CV of length of fiber bundle>

[0310] The Feret diameters of 60 or more fiber bundles were measured in the same manner as the length of the fiber bundle, and the average μ and standard deviation σ of the Feret diameters were obtained. The coefficient of variation CV was obtained by dividing the standard deviation σ by the average μ as shown in the following formula.

[0311] CV = σ / μ

[0312] [Example 1]

[0313] As the raw material fiber, carbon fiber (trade name: Pyrofil chopped fiber TR03CM, manufactured by Mitsubishi Chemical Corporation, average fiber length 3.1 mm) was used. As the particles, PEEK particles (trade name: KetaSpire KT-800SFP, manufactured by SOLVAY, powder, median particle diameter 27.4 μm) were used.

[0314] First, 350 g of carbon fiber and 250 g of PEEK particles were put into a stirring granulator (trade name: SP granulator SPG25T, manufactured by Dalton, equipment volume: 25 liters, tilt angle θ of stirring blade: 30°, stirring blade diameter 396 mm). Then, 480 g of a bundling liquid (surface tension at 23 °C: 57.7 mN / m, viscosity at 23 °C: 0.003 Pa·s) obtained by mixing 462 g of water as a liquid and 18 g of polyamide resin as an organic binder was put into the stirring granulator and stirred at a speed of 400 rpm of the stirring blade (circumferential speed of the stirring blade: 8 m / s) and 3000 rpm of the chopper (circumferential speed of the stirring blade: 11 m / s) for 6 minutes to mix, obtaining a particle-containing fiber bundle W1 containing liquid.

[0315] The particle-containing fiber bundle W1 was dried in a box dryer at 120 °C for 2 hours to obtain the long spherical particle-containing fiber bundle P1 with a fiber bundle length of 4.5 mm as Figure 5 shown.

[0316] The standard deviation and coefficient of variation CV of the fiber bundle lengths when measuring 179 particle-containing fiber bundles P1 are shown in Table 1A. As Figure 6 shown, particles exist on the surface of the fiber bundle in the particle-containing fiber bundle P1. The particle-containing fiber bundle P1 was torn and the internal state was observed. The result was as Figure 7 shown, and particles also exist uniformly inside the fiber bundle.

[0317] [Example 2]

[0318] The amount of carbon fiber used was replaced with 383 g, and the PEEK particles were replaced with 217 g of PA11 particles 1 (trade name: RILSAN-ES, manufactured by ALKEMA Corporation, powder, median particle size 32.9 μm). Otherwise, the operation was the same as in Example 1 to obtain the long spherical particle-containing fiber bundle P2 with a fiber bundle length of 5.3 mm.

[0319] The standard deviation and coefficient of variation CV of the fiber bundle lengths when measuring 156 particle-containing fiber bundles P2 are shown in Table 1A.

[0320] [Example 3]

[0321] The amount of carbon fiber used was replaced with 369 g, and the PEEK particles were replaced with 231 g of PA10T particles 1 (median particle size 92.2 μm). Otherwise, the operation was the same as in Example 1 to obtain the long spherical particle-containing fiber bundle P3 with a fiber bundle length of 4.4 mm. The PA10T particles 1 were obtained as follows: For PA10T particles (trade name: XecoT-XN500, manufactured by UNITIKA Ltd., powder, median particle size 192 μm), coarse powder was removed using a sieve with a mesh size of 250 μm (trade name: electromagnetic vibrating sieve machine A-3, manufactured by Fritsch Japan Co., Ltd.).

[0322] The standard deviation and coefficient of variation CV of the fiber bundle lengths when measuring 153 particle-containing fiber bundles P3 are shown in Table 1A.

[0323] [Comparative Example 1]

[0324] The PA11 particles 1 were replaced with PA11 particles 2 (trade name: RILSAN-T, manufactured by ALKEMA Corporation, powder, median particle size 111.6 μm). Otherwise, the operation was the same as in Example 2 to obtain the amorphous particle-containing fiber bundle P4 with a fiber bundle length of 8.4 mm.

[0325] The standard deviation and coefficient of variation CV of the lengths of 67 particle-containing fiber bundles P4 were shown in Table 1B.

[0326] [Comparative Example 2]

[0327] PA10T particles 1 were replaced with PA10T particles 2 (median particle size 176.3 μm), and otherwise, the same operations as in Example 3 were carried out to obtain an amorphous particle-containing fiber bundle P5 with a fiber bundle length of 9.4 mm. PA10T particles 2 were obtained as follows: For PA10T particles (trade name: XecoT-XN500, manufactured by UNITIKA Ltd., powder, median particle size 192 μm), coarse powder was removed using a sieve with a mesh size of 500 μm (trade name: electromagnetic vibrating sieve machine A-3, manufactured by Fritsch Japan Co., Ltd.).

[0328] The standard deviation and coefficient of variation CV of the lengths of 67 particle-containing fiber bundles P5 were shown in Table 1B.

[0329] [Example 4]

[0330] As the raw material fiber, carbon fiber (trade name: Pyrofil chopped fiber TR03CM, manufactured by Mitsubishi Chemical Corporation, average fiber length 3.1 mm) was used. As the particles, glass beads (trade name: EJ-2500, manufactured by Potters-Ballotini Co., Ltd., powder, median particle size 4.9 μm) were used.

[0331] First, 84 g of carbon fiber and 116 g of glass beads were put into a stirring granulator (trade name: Henschel mixer FM10B, manufactured by Mitsui Miike Works, Ltd., equipment volume: 9 liters). Then, 160 g of a bundling liquid (surface tension at 23°C: 57.7 mN / m, viscosity at 23°C: 0.003 Pa·s) obtained by mixing 154 g of water as a liquid and 6 g of polyamide resin as an organic binder was put into the stirring granulator and stirred at a speed of 1195 rpm of the stirring blade (circumferential speed of the stirring blade: 13 m / s) for 2 minutes to carry out mixing, obtaining a particle-containing fiber bundle W2 containing a liquid.

[0332] The fiber bundle W2 was dried in a box-type dryer at 120°C for 2 hours to obtain a long spherical particle-containing fiber bundle P6 with a fiber bundle length of 11.7 mm.

[0333] The standard deviation and coefficient of variation CV of the lengths of 60 particle-containing fiber bundles P6 were shown in Table 1B.

[0334] [Example 5]

[0335] Replace the glass beads with glass beads (product name: J-800, manufactured by Potters-Ballotini, powder, median particle size 24.6 μm). Otherwise, operate in the same manner as in Example 4 to obtain the long spherical particle-containing fiber bundle P7 with a fiber bundle length of 12.2 mm.

[0336] The standard deviation and coefficient of variation CV of the fiber bundle lengths when measuring 112 particle-containing fiber bundles P7 are shown in Table 1B.

[0337] [Example 6]

[0338] Replace the glass beads with glass beads (product name: J-320, manufactured by Potters-Ballotini, powder, median particle size 51 μm). Otherwise, operate in the same manner as in Example 4 to obtain the long spherical particle-containing fiber bundle P8 with a fiber bundle length of 12.6 mm.

[0339] The standard deviation and coefficient of variation CV of the fiber bundle lengths when measuring 73 particle-containing fiber bundles P8 are shown in Table 1B.

[0340] [Examples 7 to 10]

[0341] Change the usage amounts of the raw material fibers, particles, liquid, and organic binder as shown in Table 1A. Otherwise, operate in the same manner as in Example 1 to obtain the long spherical particle-containing fiber bundles P9 to 12 with the fiber bundle lengths shown in Table 1A.

[0342] The standard deviation and coefficient of variation CV of the fiber bundle lengths when measuring the particle-containing fiber bundles P9 to 12 are shown in Table 1A.

[0343] [Table 1A]

[0344]

[0345] [Table 1B]

[0346]

[0347] From the results in Table 1, it can be seen that in Examples 1 to 10, long spherical particle-containing fiber bundles were obtained, and the CV, which is an index representing the uniformity of the fiber bundle lengths, was 0.19 to 0.32. In Comparative Examples 1 and 2, amorphous particle-containing fiber bundles were obtained under the same stirring conditions as in Examples 1 to 3, and the CV was greater than 0.43.

[0348] Symbol Explanation

[0349] 1 Stirring tank

[0350] 2 Rotating shaft

[0351] 3 Stirring blade

[0352] 40 containers

[0353] 42 rotating shaft part

[0354] 44 stirring blades

[0355] 45 scraper blade.

Claims

1. A manufacturing method of a particle-containing fiber bundle, which is a manufacturing method of a particle-containing fiber bundle in an oblate spheroid shape or a strand shape, The manufacturing method of the particle-containing fiber bundle includes: The step of mixing a plurality of short-sized fibers, particles with a median particle size of 100 μm or less, an organic binder, and a liquid, As the fiber, it includes carbon fiber, 10 parts by mass or more of the particles are used with respect to 100 parts by mass of the fiber.

2. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the median particle size of the particles is 3 μm or more.

3. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the solubility of the particles in the liquid is 0.01 g / 100 g or less.

4. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the solubility of the particles in water is 0.0001 g / 100 g or less.

5. The manufacturing method of the particle-containing fiber bundle according to claim 4, wherein the solubility of the organic binder in water is greater than 0.001 g / 100 g.

6. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the particles include organic particles.

7. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein 20 parts by mass or more and 80 parts by mass or less of the particles are used with respect to 100 parts by mass of the fiber.

8. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein 55 parts by mass or more and 75 parts by mass or less of the particles are used with respect to 100 parts by mass of the fiber.

9. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the organic binder includes at least one resin selected from the group consisting of polyamide resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, and polyurethane resin.

10. The manufacturing method of the particle-containing fiber bundle according to claim 6, wherein the organic particles include thermoplastic resin particles.

11. The manufacturing method of the particle-containing fiber bundle according to claim 10, wherein the thermoplastic resin particles include at least one selected from the group consisting of polyamide resin, polyolefin resin, polyester resin, polycarbonate resin, polyethersulfone resin, polyetheretherketone resin, polyetherimide resin, and polyphenylene sulfide resin.

12. The manufacturing method of the particle-containing fiber bundle according to claim 6, wherein the organic particles include thermosetting resin particles.

13. The manufacturing method of the particle-containing fiber bundle according to claim 12, wherein the thermosetting resin particles include at least one selected from the group consisting of epoxy resin, vinyl ester resin, unsaturated polyester resin, cyanate ester resin, polyimide resin, maleimide resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane resin, and phenolic resin.

14. The manufacturing method of the particle-containing fiber bundle according to claim 6, wherein the organic particles include curing agent particles.

15. The manufacturing method of the particle-containing fiber bundle according to claim 14, wherein as the curing agent particles, it contains at least one selected from the group consisting of dicyandiamide-based, phenol-based, amine-based, carboxylic anhydride-based, thiol-based, imidazole-based, phosphine-based, peroxide-based, and organic metal salt-based.

16. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein as the particles, it contains inorganic particles.

17. The manufacturing method of the particle-containing fiber bundle according to claim 16, wherein as the inorganic particles, it contains at least one selected from the group consisting of metal particles, metal oxide particles, silica particles, silicate particles, carbonate particles, sulfate particles, hydroxide particles, glass particles, ceramic particles, graphite, and carbon black.

18. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the particle size D90 at which the cumulative value in the volume-based particle size distribution of the particles becomes 90% is 250 μm or less.

19. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the particle size D10 at which the cumulative value in the volume-based particle size distribution of the particles becomes 10% is 50 μm or less.

20. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the particle size D90 at which the cumulative value in the volume-based particle size distribution of the particles becomes 90% is 0.5 μm or more.

21. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the particle size D10 at which the cumulative value in the volume-based particle size distribution of the particles becomes 10% is 0.05 μm or more.

22. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the ratio D75 / D25 of the particle size D75 at which the cumulative value in the volume-based particle size distribution of the particles becomes 75% to the particle size D25 at which the cumulative value becomes 25% is 1 to 15.

23. The manufacturing method of the particle-containing fiber bundle according to claim 1, using a fiber batting containing the fibers.

24. The manufacturing method of the particle-containing fiber bundle according to claim 1, using a stirring granulator.

25. The manufacturing method of the particle-containing fiber bundle according to claim 24, wherein the stirring granulator includes a stirring tank.

26. The manufacturing method of the particle-containing fiber bundle according to claim 25, wherein stirring blades are provided inside the stirring tank.

27. The manufacturing method of the particle-containing fiber bundle according to claim 25, wherein the stirring tank is equipped with a scraper.

28. The manufacturing method of the particle-containing fiber bundle according to claim 26, wherein the distance between the bottom surface of the stirring blade and the bottom surface of the stirring tank is 1 mm or less.

29. The manufacturing method of the particle-containing fiber bundle according to claim 26, wherein the distance between the tip of the stirring blade and the wall surface of the stirring tank is 10 mm or more.

30. The manufacturing method of the particle-containing fiber bundle according to claim 25, rotating the stirring tank.

31. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the average fiber length of the fibers is 12 to 50 mm.

32. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the average fiber length of the fibers is 2 to 12 mm.

33. The manufacturing method of the fiber bundle containing particles according to claim 1, wherein the volume density of the fiber is 0.01 to 0.1 g / cm 3 .

34. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the front end positions of the fibers constituting the particle-containing fiber bundle are inconsistent.

35. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the length of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the particle-containing fiber bundle.

36. The manufacturing method of the fiber bundle containing particles according to claim 1, comprising: Mixing the particles, the organic binder, and the liquid to obtain Mixture 1; And mixing Mixture 1 and the fibers to obtain Mixture 2.

37. The manufacturing method of the particle-containing fiber bundle according to claim 1, including removing the liquid.

38. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein 60 to 200 parts by mass of the liquid is used relative to 100 parts by mass of the fibers.

39. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein 1 to 40 parts by mass of the organic binder is used relative to 100 parts by mass of the fibers.

40. The manufacturing method of the particle-containing fiber bundle according to claim 1, wherein the particles and the organic binder are used such that the mass ratio of the particles to the organic binder, i.e., mass of particles / mass of organic binder, is 2.5 to 100.

41. A particle-containing fiber bundle, which comprises a plurality of fibers having been short-sized, particles with a median particle diameter of 100 μm or less, and an organic binder, and has an oblong spherical shape or a strand shape, As the fibers, carbon fibers are included, Relative to 100 parts by mass of the fibers, 10 parts by mass or more of the particles are included.

42. The particle-containing fiber bundle according to claim 41, wherein the fibers are aligned.

43. The particle-containing fiber bundle according to claim 41, wherein the particles include organic particles.

44. The particle-containing fiber bundle according to claim 41, wherein the median particle diameter of the particles is 3 μm or more.

45. The particle-containing fiber bundle according to claim 41, wherein the average fiber length of the fibers is 12 to 50 mm.

46. The particle-containing fiber bundle according to claim 41, wherein the average fiber length of the fibers is 2 to 12 mm.

47. The particle-containing fiber bundle according to claim 41, wherein the front end positions of the fibers constituting the particle-containing fiber bundle are inconsistent.

48. The particle-containing fiber bundle according to claim 41, wherein the length of the particle-containing fiber bundle is longer than the average fiber length of the fibers contained in the particle-containing fiber bundle.

49. The particle-containing fiber bundle according to claim 41, wherein the ratio of the length of the particle-containing fiber bundle to the average fiber length of the fibers contained in the particle-containing fiber bundle, i.e., length of particle-containing fiber bundle / average fiber length of fibers contained in particle-containing fiber bundle, is 1.1 to 2.

5.

50. The particle-containing fiber bundle according to claim 41, wherein the mass content rate of the particles in the particle-containing fiber bundle is 20 to 80 mass%.

51. The particle-containing fiber bundle according to claim 41, wherein the mass content rate of the organic binder in the particle-containing fiber bundle is 0.5 to 20 mass%.

52. The particle-containing fiber bundle according to claim 41, wherein the mass ratio of the particles to the organic binder in the particle-containing fiber bundle, that is, the mass of the particles / the mass of the organic binder, is 2.5 to 100.

53. The particle-containing fiber bundle according to claim 41, wherein the fiber comprises a regenerated fiber.

Images