Fiber-reinforced thermoplastic resin filament and molded article thereof

Abstract

Provided is a fiber-reinforced thermoplastic resin filament wherein: at least one substance selected from the group consisting of polyphenylene sulfide resins, polyarylene ether ketone resins, polyamides, polycarbonates, polyether imide resins, polyethersulfone resins, and liquid crystal polymer resins is impregnated in a plurality of continuous reinforcement fibers; in a cross-section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament, the inner-outer ratio of the reinforcement fibers is 0-90%, said inner-outer ratio being defined as the ratio of the volume content of the reinforcement fibers in an outer peripheral portion that spans 15% of the thickness of the filament inward from the outer edge, to the volume content of the reinforcement fibers in an inner portion that excludes the outer peripheral portion; and the coefficient of static friction of the surface is 0.20-0.80. The filament slides easily in a material feeding mechanism of a 3D printer. This solves the problem wherein a filament is not supplied at a stable speed to a nozzle, thereby making it easy for the filament to become stuck the nozzle and reducing molding precision.

Description

Fiber-reinforced thermoplastic resin filaments and molded products thereof

[0001] The present invention relates to a fiber-reinforced thermoplastic resin filament suitable for use in 3D printers and a molded article thereof.

[0002] Fiber-reinforced thermoplastic resin substrates formed by impregnating a plurality of continuous reinforcing fibers with a thermoplastic resin have excellent specific strength and specific rigidity, a high weight-saving effect, and high heat resistance and chemical resistance, and are therefore preferably used in various applications such as transportation equipment such as aircraft and automobiles, industrial applications, sports, and electrical and electronic components (see, for example, Patent Documents 1 and 2). In recent years, due to the increasing demand for weight reduction, metal parts have been replaced by resin parts, and parts have been miniaturized and modularized, mainly in aircraft and automobile applications. Therefore, there is a demand for the development of materials with excellent moldability and mechanical properties.

[0003] In recent years, molding methods for melt-laminating thermoplastic resins, such as 3D printing, have been attracting attention as a molding method for fiber-reinforced thermoplastic resin substrates. The method of creating a shape by melt-laminating a thermoplastic resin has been developed in various fields due to its cost advantages (e.g., Patent Document 3). The mainstream method for fiber-reinforced thermoplastic resin substrates applied to such molding methods is to extrude short-cut reinforcing fibers together with a thermoplastic resin to produce fiber-reinforced thermoplastic resin strands. However, it is difficult to increase the fiber content of short-fiber-reinforced thermoplastic resin substrates, and the reinforcing effect is limited due to the short fiber length.

[0004] As a method for achieving a high reinforcing effect, a method of applying a continuous fiber reinforced thermoplastic resin substrate as shown in Patent Document 4 has been investigated.

[0005] Japanese Patent Laid-Open No. 2013-26171 Japanese Patent Laid-Open No. 5-50434 Special Publication No. 2009-500194 Japanese Patent Laid-Open No. 2017-128072

[0006] The continuous fiber reinforced thermoplastic resin substrate described in Patent Document 4 is intended to provide a method for manufacturing three-dimensional structures with few internal voids or bubbles by using a mixed fiber yarn as a filament for 3D printers. However, the use of a mixed woven filament with poor impregnation properties poses the problem of reduced rigidity and strength of the molded product. Furthermore, 3D printer filaments with poor impregnation properties are prone to variations in the amount of resin in the surface layer, and in areas with a low resin content in the surface layer, the coefficient of friction decreases, making the filament more likely to slip in the material feed mechanism.

[0007] Furthermore, even for fiber-reinforced thermoplastic resin filaments for 3D printers with good impregnation properties, those with a high carbon fiber ratio at the periphery tend to have a low static friction coefficient approaching the static friction coefficient of carbon fiber, which is 0.1. When the static friction coefficient of a filament is low, the filament tends to slip easily in the material feed mechanism of the 3D printer, preventing the filament from being fed to the nozzle at a stable speed, making it more likely to clog the nozzle and reducing modeling accuracy.

[0008] In order to solve the above problems, the present invention mainly has the following configurations. [1] A fiber-reinforced thermoplastic resin filament comprising a plurality of continuous reinforcing fibers impregnated with at least one selected from the group consisting of polyphenylene sulfide resin (PPS), polyarylene ether ketone resin (PAEK), polyamide (PA), polycarbonate (PC), polyetherimide resin (PEI), polyethersulfone resin (PES), and liquid crystal polymer resin (LCP), wherein in a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament, the inner-outer ratio of reinforcing fibers, defined as the ratio of the volume content of reinforcing fibers in the outer peripheral portion extending from the outer edge to 15% inside the filament thickness to the volume content of reinforcing fibers in the inner portion excluding the outer peripheral portion, is 0 to 90%, and the surface static friction coefficient is 0.20 to 0.80. [2] The fiber-reinforced thermoplastic resin filament according to [1], wherein the static friction coefficient is 0.20 to 0.40. [3] The fiber-reinforced thermoplastic resin filament according to [1], wherein the inner / outer ratio is 10 to 60%. [4] The fiber-reinforced thermoplastic resin filament according to [1], wherein the surface roughness Ra is 0.50 to 20 μm. [5] The fiber-reinforced thermoplastic resin filament according to [1], wherein the average value D of the dispersion parameter d [%] measured by the following methods (i) to (iv) is 90% or more. (i) A photograph of a cross section perpendicular to the axial direction of the filament is taken so that the entire cross section of the fiber-reinforced thermoplastic resin filament is captured. (ii) The entire cross-sectional image is divided into square units having a side length defined by (Equation 4). (iii) The dispersion parameter d [%] defined by (Equation 5) is calculated. (iv) The steps (i) to (iii) are repeated at multiple locations on the fiber-reinforced thermoplastic resin filament, and the average value D of the dispersion parameter d [%] is calculated. (Equation 4) t = 2.5a (a: fiber diameter, t: length of one side of the unit) (Equation 5) Dispersion parameter d [%] = number of units containing reinforcing fiber within the evaluation section / total number of units containing at least a portion of the filament within the evaluation section × 100 [6] The fiber-reinforced thermoplastic resin filament for 3D printers described in [5], wherein the coefficient of variation of the multiple dispersion parameters d used to calculate the average value D is 4% or less.[7] The fiber-reinforced thermoplastic resin filament according to [1], wherein a fiber twisted at 50 T / m or less is wound around the reinforcing fiber of the fiber-reinforced thermoplastic resin filament as a covering yarn. [8] The fiber-reinforced thermoplastic resin filament according to [7], wherein the surface roughness Ra is 10 to 20 μm. [9] The fiber-reinforced thermoplastic resin filament according to [1], wherein the thermoplastic resin contains a filler.

[10] The fiber-reinforced thermoplastic resin filament according to [1], wherein the inner-outer ratio is 15 to 80%, the thickness is 0.01 to 3 mm, and the filament length is 1 m or more.

[11] The fiber-reinforced thermoplastic resin filament according to [1], wherein the porosity is 10% or less.

[12] The fiber-reinforced thermoplastic resin filament according to [1], wherein the reinforcing fiber is carbon fiber.

[13] A molded product obtained using the fiber-reinforced thermoplastic resin filament according to [1].

[0009] According to the present invention, the static friction coefficient of the filament can be reduced and slippage of the filament in the material feed mechanism during molding using a 3D printer can be suppressed, so high dimensional accuracy can be expected for molded products obtained using this method.

[0010] FIG. 1 is a schematic diagram illustrating the thickness of a circular cross section filament of the present invention. FIG. 2 is a schematic diagram illustrating the thickness of an elliptical cross section filament of the present invention. FIG. 3 is a schematic diagram illustrating the thickness of a modified cross section filament (1) of the present invention. FIG. 4 is a schematic diagram illustrating the thickness of a modified cross section filament (2) of the present invention. FIG. 5 is a schematic diagram of a jig for measuring the coefficient of friction according to the present invention. FIG. 6 is a schematic diagram of an apparatus for measuring the coefficient of friction according to the present invention. FIG. 7 is a schematic diagram illustrating the outer periphery of a filament of the present invention. FIG. 8 is a schematic diagram illustrating a method of winding a covering yarn around the core of a filament of the present invention.

[0011] DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to embodiments. The fiber-reinforced thermoplastic resin filament according to the present invention is formed by impregnating a plurality of continuous reinforcing fibers with a thermoplastic resin.

[0012] In the present invention, continuous reinforcing fibers refer to reinforcing fibers that are substantially uninterrupted in the fiber-reinforced thermoplastic resin. Ideally, all single threads in the filament are uninterrupted, but if 80% or more of the single threads are uninterrupted, the filament can be said to be in an "uninterrupted" state. Examples of the form and arrangement of the reinforcing fibers in the present invention include those that are aligned in one direction, braids, tows, etc. Among these, it is preferable that the reinforcing fibers are aligned in one direction, as this can efficiently improve the mechanical properties in a specific direction.

[0013] The types of reinforcing fibers and covering yarns described later are not particularly limited, and examples include inorganic fibers such as carbon fibers, metal fibers, and organic fibers. Two or more of these may be used.

[0014] Examples of carbon fibers include polyacrylonitrile (PAN)-based carbon fibers made from PAN fibers, pitch-based carbon fibers made from petroleum tar or petroleum pitch, cellulose-based carbon fibers made from viscose rayon or cellulose acetate, vapor-grown carbon fibers made from hydrocarbons, graphitized fibers of these, etc. Among these carbon fibers, PAN-based carbon fibers are preferably used because of their excellent balance between strength and elastic modulus.

[0015] Examples of metal fibers include fibers made of metals such as iron, gold, silver, copper, aluminum, brass, and stainless steel.

[0016] Examples of organic fibers include fibers made of organic materials such as aramid, polybenzoxazole (PBO), polyphenylene sulfide, polyester, polyamide, and polyethylene. Examples of aramid fibers include para-aramid fibers, which have excellent strength and elastic modulus, and meta-aramid fibers, which have excellent flame retardancy and long-term heat resistance. Examples of para-aramid fibers include polyparaphenylene terephthalamide fibers and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers, and examples of meta-aramid fibers include polymetaphenylene isophthalamide fibers. As the aramid fiber, para-aramid fibers, which have a higher elastic modulus than meta-aramid fibers, are preferably used.

[0017] Other inorganic fibers include, for example, fibers made of inorganic materials such as glass, basalt, silicon carbide, and silicon nitride. Glass fibers include, for example, E-glass fiber (for electrical use), C-glass fiber (for corrosion resistance), S-glass fiber, and T-glass fiber (high strength, high elastic modulus). Basalt fiber is a fiber made from the mineral basalt, and is a fiber with extremely high heat resistance. Basalt generally contains FeO or FeO, which are compounds of iron. ２ 9 to 25% by weight of titanium compounds TiO or TiO ２ However, it is possible to increase the amount of these components in the molten state to form fibers.

[0018] The fiber-reinforced thermoplastic resin filament in the embodiment of the present invention is often expected to function as a reinforcing material, and therefore it is desirable that it exhibit high mechanical properties. In order to exhibit high mechanical properties, it is preferable that it contains carbon fiber as a reinforcing fiber.

[0019] In fiber-reinforced thermoplastic resin filaments, the reinforcing fibers, excluding covering yarns, are typically composed of one or more reinforcing fiber bundles each made up of a large number of single fibers. The number of single fibers in the reinforcing fiber bundles when one or more reinforcing fiber bundles are arranged is preferably 500 to 50,000. From the viewpoint of ease of handling, the number of single fibers in the reinforcing fiber is more preferably 1,000 to 50,000, even more preferably 1,000 to 40,000, and particularly preferably 1,000 to 30,000. Unlike UD tapes, the reinforcing fibers in fiber-reinforced thermoplastic resin filaments are fed from a single bobbin around which a reinforcing fiber bundle is wound.

[0020] The upper limit of the number of single reinforcing fibers may be any number that maintains good dispersibility and ease of handling, taking into consideration the balance between quality such as voids and dispersibility and ease of handling.

[0021] The fiber-reinforced thermoplastic resin filament of the present invention has a static friction coefficient in the range of 0.20 to 0.80. This range has the effect of suppressing slippage of the filament in the material feed mechanism during molding using a 3D printer, enabling molding with high dimensional accuracy. The static friction coefficient is preferably 0.20 to 0.60, and particularly preferably 0.20 to 0.40.

[0022] In the present invention, the outermost layer of the fiber-reinforced thermoplastic resin filament can be coated with a thermoplastic resin. In this case, the fiber-reinforced thermoplastic resin filament excluding the outermost thermoplastic resin layer is defined as the core, and the outside of the core may be completely coated, or the fiber-reinforced thermoplastic resin filament may be partially present on the outside. By coating the outermost layer with a thermoplastic resin, adhesion during molding can be improved. The coating resin may be the same as or a different resin from the fiber-reinforced thermoplastic resin filament. The presence of a resin layer on the outer edge of the fiber-reinforced thermoplastic resin filament can improve adhesion between the filaments (in the lateral direction or thickness direction of the molding) during 3D printing. The coating resin may also include a covering yarn.

[0023] The covering yarn is a fiber bundle wound around the core of the fiber-reinforced thermoplastic resin filament. By adding the covering yarn, the covering yarn forms a convex shape, which has the effect of increasing the surface roughness Ra of the filament.

[0024] As a method for winding the covering thread, the drawing method described below will be shown as an example.

[0025] After the fiber-reinforced thermoplastic resin filament is pulled out from the nozzle of the impregnation die, it is passed through the axial hole of a bobbin around which a covering thread is wound, and the bobbin is set so that it can rotate about its axis. After the filament passes through the axial hole, it is heated with a heat source such as an infrared heater, and the covering thread is attached to the surface of the molten filament while being wound around it.

[0026] In this case, by adjusting the speed at which the bobbin is rotated relative to the filament feed speed, the covering yarn can be wound around the filament with the desired number of twists.

[0027] The static friction coefficient of the fiber-reinforced thermoplastic resin filament is measured and evaluated as follows.

[0028] (Method for evaluating the static friction coefficient) The fiber-reinforced thermoplastic resin filaments were conditioned for at least 16 hours under the standard atmosphere conditions of 23±2°C and 50±6% RH specified in JIS K 7100. The surfaces of the fiber-reinforced thermoplastic resin filaments were kept free from dust, fingerprints, or other foreign matter that could alter the surface properties.

[0029] As shown in Figure 5, a plate 5 with fiber-reinforced thermoplastic resin filaments 6 and 7 attached in parallel and a plate 8 with fiber-reinforced thermoplastic resin filaments 9 and 10 attached in parallel were prepared, and after stacking them, they were placed on the tilt angle adjustment stage 11 shown in Figure 6. The measurements were also carried out in a standard atmosphere of 23 ± 2 ° C and 50 ± 6% RH.

[0030] At this time, the filaments of plates 5 and 8 are overlapped so that they are perpendicular to each other. The tilt angle adjustment stage 11 is tilted at 1.5° / sec, and tan θ is calculated from the angle θ at which the fiber-reinforced thermoplastic resin filaments start to slide, as shown in Figure 6, and this is used as the static friction coefficient. Specifically, this is evaluated based on the examples described below.

[0031] The surface roughness Ra of the fiber-reinforced thermoplastic resin filament of the present invention is measured using a contact surface roughness meter in accordance with JIS B0601:2013. Specifically, it is evaluated based on the examples described later.

[0032] The thickness of a fiber-reinforced thermoplastic resin filament according to an embodiment of the present invention refers to the value at which the distance between the two parallel lines is minimum when the outer edge of the fiber-reinforced thermoplastic resin filament is sandwiched between two parallel lines in a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament. Examples of thickness measurements are shown in Figures 1 to 4. Figure 1 shows an example of measuring the thickness of a circular cross-section filament, which has a constant value regardless of the measurement location. Figure 2 shows an example of measuring the thickness of an elliptical cross-section filament, which has a minimum value when the measurement location is sandwiched between the minor axis side of the ellipse. Figures 3 and 4 are both examples of measuring the thickness of a modified cross-section filament, which show that the thickness does not change even if there is a depression inside the parallel lines.

[0033] As shown in FIG. 7, the outer periphery of the fiber-reinforced thermoplastic resin filament according to an embodiment of the present invention is a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament. The cross-sectional area is defined as a diagonal line area surrounded by an outer edge 14 and a parallel curve 15 moved inward by a distance of 15% of the thickness from the outer edge.

[0034] The volume content of the fibers in the outer periphery is preferably in the range of 0 to 90% of the volume content of the fibers in the inner portion excluding the outer periphery, more preferably in the range of 5 to 80%, and even more preferably in the range of 10 to 60%. When the volume content is in this range, the resin content in the surface layer is high, which has the effect of suppressing a decrease in the static friction coefficient.

[0035] The fiber-reinforced thermoplastic resin filament of the present invention preferably has a surface roughness Ra in the range of 0.50 to 20 μm. When this range is set, the uneven shape of the filament surface makes it less likely to slip in the material feeding mechanism of the 3D printer, which has the effect of enabling molding with high dimensional accuracy.

[0036] The surface roughness Ra is more preferably in the range of 0.50 to 10 μm, even more preferably in the range of 0.70 to 5 μm, and particularly preferably in the range of 1 to 3 μm.

[0037] The fiber volume content (Vf) of the fiber-reinforced thermoplastic resin filament of the present invention preferably contains 15 to 80% by volume of reinforcing fibers when the entire fiber-reinforced thermoplastic resin filament is taken as 100% by volume. By containing 15% by volume or more of reinforcing fibers, the strength of molded products obtained using the fiber-reinforced thermoplastic resin filament can be further improved. Vf is more preferably 30% by volume or more, and even more preferably 40% by volume or more. On the other hand, by containing 80% by volume or less of reinforcing fibers, it is easier to impregnate the reinforcing fibers with the thermoplastic resin. The reinforcing fibers in the fiber-reinforced thermoplastic resin filament are more preferably 75% by volume or less, and even more preferably 70% by volume or less.

[0038] (Method for evaluating fiber volume content (Vf)) The volume content of the reinforcing fibers of a fiber-reinforced thermoplastic resin filament is measured and evaluated as follows. A sample is prepared by embedding a fiber-reinforced thermoplastic resin filament as a specimen in epoxy resin, and the sample is polished until a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament can be clearly observed. The polished sample is photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit (manufactured by Keyence Corporation)).

[0039] In the photographed cross-sectional image, the ratio of the total area of ​​the reinforcing fibers included in the total area to the total area surrounded by the outer edges of the fiber-reinforced thermoplastic resin filaments is calculated, and the volume content of the reinforcing fibers is calculated using the following formula (1): (Formula 1) Volume content of reinforcing fibers [%] = 100 × (total area of ​​reinforcing fibers) / (total area of ​​fiber-reinforced thermoplastic resin filaments)

[0040] Furthermore, when coating the outermost layer with resin, a parallel curve is drawn inward from the outer edge of the fiber-reinforced thermoplastic resin filament by 15% of the filament thickness inward in the photographed cross-sectional image, and the volume content of the reinforcing fibers is calculated outside and inside the parallel curve using the above (Equation 1). The inner / outer ratio of the reinforcing fibers is calculated for each of the three cross sections using (Equation 2), and the arithmetic average value is taken as the inner / outer ratio of the reinforcing fibers. (Equation 2) Inner / outer ratio of reinforcing fibers [%] = 100 × (volume content of reinforcing fibers in the outer periphery) / (volume content of reinforcing fibers in the inner part excluding the outer periphery).

[0041] When twisted fibers are wound around the reinforcing fibers of the fiber-reinforced thermoplastic resin filament as covering yarns, the number of twists is measured in accordance with JIS L1013: 2021. Here, the fibers used as covering yarns may be the same type of fibers as the reinforcing fibers of the fiber-reinforced thermoplastic resin filament, or other types of fibers may be used.

[0042] The fiber-reinforced thermoplastic resin filament of the present invention preferably has a twist number of 50 T / m or less. However, a twist number of 0 T / m is not included. By setting the twist number within this range, the twisted yarn forms regular irregularities in the longitudinal direction, which has the effect of making it less likely to slip in the material feed mechanism of a 3D printer. The twist number is preferably 5 to 30 T / m, and more preferably 10 to 20 T / m. When used in this manner, the fiber-reinforced thermoplastic resin filament of the present invention preferably has a surface roughness Ra in the range of 10 to 20 μm. Setting the twist number within this range has the effect of making it less likely to slip in the material feed mechanism of a 3D printer due to the irregular shape formed by the twisted yarn on the filament surface.

[0043] In the present invention, one reinforcing fiber bundle is preferably formed by bundling 500 to 50,000 reinforcing fiber single fibers each having an average diameter of 5 to 10 μm.

[0044] In the fiber-reinforced thermoplastic resin filament according to the present invention, the thermoplastic resin is preferably a polymer alloy. By using a thermoplastic polymer alloy resin, impregnation properties, mechanical properties, and adhesiveness can be improved. For example, by using a polymer alloy consisting of a high-viscosity thermoplastic resin and a low-viscosity thermoplastic resin as the thermoplastic resin, both high mechanical properties and impregnation properties can be achieved. Furthermore, by using a polymer alloy consisting of a highly tough resin as the thermoplastic resin, the interlayer strength when the fiber-reinforced thermoplastic resin filament is shaped is improved.

[0045] Examples of thermoplastic resins that can be used in the present invention include polyesters such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate (PTT) resin, polyethylene naphthalate (PEN) resin, and liquid crystal polyester resin; polyolefins such as polyethylene (PE) resin, polypropylene (PP) resin, and polybutylene resin; and styrene-based resins, as well as polyoxymethylene (POM) resin, polyamide (PA) resin, polycarbonate (PC) resin, polymethylene methacrylate (PMMA) resin, polyvinyl chloride (PVC) resin, polyphenylene sulfide (PPS) resin, polyphenylene ether (PPE) resin, modified PPE resin, polyimide (PI) resin, and polyamideimide ( Fluorine-based resins such as PAI resin, polyetherimide (PEI) resin, polysulfone (PSU) resin, modified PSU resin, polyethersulfone resin, polyketone (PK) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, polyetherketoneketone (PEKK) resin, polyarylate (PAR) resin, polyethernitrile resin, phenolic resin, phenoxy resin, and polytetrafluoroethylene resin, as well as thermoplastic elastomers such as polystyrene resin, polyolefin resin, polyurethane resin, polyester resin, polyamide resin, polybutadiene resin, polyisoprene resin, and fluorine-based resin, copolymers, modified products, and blends of two or more of these resins may also be used. In particular, from the viewpoint of heat resistance and long-term durability, polyphenylene sulfide resin, polyarylene ether ketone resin, polyetherimide resin, polyethersulfone resin, and liquid crystal polymer resin are more preferred.

[0046] Examples of the polyarylene ether ketone (PAEK) resin include polyether ketone (PEK), polyether ether ketone (PEEK), polyether ether ketone ketone (PEEKK), polyether ketone ketone (PEKK), polyether ketone ether ketone ketone (PEKEKK), polyether ether ketone ether ketone (PEEKEK), polyether ether ether ketone (PEEEK), and polyether diphenyl ether ketone (PEDEK), as well as copolymers, modified products, and blends of two or more of these resins.

[0047] The polymer alloy constituting the thermoplastic resin in the present invention preferably forms, in the fiber-reinforced thermoplastic resin filament, a biphase continuous structure with a structural period of 0.001 to 10 μm, or a sea-island structure consisting of island and sea phases with particle sizes of 0.001 to 10 μm. By controlling the biphase continuous structure to a range of 0.001 μm to 10 μm, or a sea-island structure consisting of island and sea phases with particle sizes of 0.001 to 1 μm, high mechanical properties and heat resistance can be achieved. It is more preferable to form a biphase continuous structure with a range of 0.01 μm to 5 μm, or a sea-island structure consisting of island and sea phases with particle sizes of 0.01 to 5 μm, and even more preferable to form a biphase continuous structure with a range of 0.1 μm to 1 μm, or a particle size of 0.05 to 1 μm.

[0048] Furthermore, in order to confirm the existence of these biphasic structures or dispersed structures, it is important to confirm the existence of a regular periodic structure. For example, in addition to confirming the formation of a biphasic structure by observation under an optical microscope or a transmission electron microscope, it is necessary to confirm the appearance of a scattering maximum in scattering measurements performed using a small-angle X-ray scattering device or a light scattering device. The presence of a scattering maximum in this scattering measurement is proof of the existence of a regular phase-separated structure with a certain period, and this period Λm (nm) corresponds to the structural period in the case of a biphasic structure, and to the interparticle distance in the case of a dispersed structure. Furthermore, this value can be calculated using the wavelength λ (nm) of the scattered light in the scatterer and the scattering angle θm (deg) that gives the scattering maximum using the following formula: Λm = (λ / 2) / sin(θm / 2)

[0049] Furthermore, even if the size of the structural period in the bicontinuous structure or the interparticle distance in the dispersed structure is within the above-mentioned range, if there are some structurally coarse portions, for example, when subjected to an impact, destruction may progress from that point, and the inherent properties of the polymer alloy may not be obtained. Therefore, the uniformity of the interparticle distance in the structural period in the bicontinuous structure or the dispersed structure of the polymer alloy is important. This uniformity can be evaluated by small-angle X-ray scattering measurement or light scattering measurement of the above-mentioned polymer alloy. Since small-angle X-ray scattering measurement and light scattering measurement have different analyzable phase-separation structure sizes, they must be used appropriately depending on the phase-separation structure size of the polymer alloy to be analyzed. Small-angle X-ray scattering measurement and light scattering measurement provide information on the size of the interparticle distance in the structural period in the bicontinuous structure or the dispersed structure, as well as information on its distribution. Specifically, the peak position of the scattering maximum in the spectrum obtained by these measurements, i.e., the scattering angle θm (deg), corresponds to the size of the structural period in the bicontinuous structure or the interparticle distance in the dispersed structure, and the broadening of the peak corresponds to the uniformity of the structure. In order to obtain excellent physical properties such as mechanical properties, high structural uniformity is preferable, and the polymer alloy of the present invention is characterized by having a maximum value in the scattering spectrum obtained by small-angle X-ray scattering measurement or light scattering measurement.

[0050] The fiber-reinforced thermoplastic resin filament of the present invention is obtained by impregnating a plurality of continuous reinforcing fibers with the above-mentioned thermoplastic resin, and if necessary, further contains a filler, other polymers, various additives, etc. It may be.

[0051] The filler contained in the fiber reinforced thermoplastic resin filament according to the present invention can be any filler generally used as a filler for resins, and the strength, rigidity, heat resistance, and dimensional stability of the fiber reinforced thermoplastic resin substrate and molded products using the same can be further improved. Examples of fillers include fibrous inorganic fillers such as glass fiber, carbon fiber, carbon nanotubes, potassium titanate whiskers, zinc oxide whiskers, aluminum borate whiskers, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, and metal fiber; non-fibrous inorganic fillers such as wollastonite, zeolite, sericite, kaolin, mica, talc, clay, pyrophyllite, bentonite, montmorillonite, asbestos, aluminosilicate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, iron oxide, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, glass beads, ceramic beads, boron nitride, silicon carbide, and silica; and particulate fillers of Cu, Al, Ti, Ag, Ni, Zn, Sn, Mo, Fe, Ta, Nb, Si, Cr, and alloys thereof. Two or more of these may be contained. These fillers may be hollow. They may also be treated with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, or an epoxy compound. Organo-montmorillonite, in which interlayer ions are cation-exchanged with an organic ammonium salt, may also be used as the montmorillonite. If the fibrous filler is made of discontinuous fibers, it can be given functionality without impairing the reinforcing effect of the reinforcing fibers made of continuous fibers.

[0052] Examples of various additives include antioxidants and heat stabilizers (hindered phenols, hydroquinones, phosphites and their substitution products, copper halides, iodine compounds, etc.), weathering agents (resorcinols, salicylates, benzotriazoles, benzophenones, hindered amines, etc.), release agents and lubricants (aliphatic alcohols, aliphatic amides, aliphatic bisamides, bisurea, polyethylene wax, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), dyes (nigrosine, aniline black, etc.), plasticizers (octyl p-oxybenzoate, N- butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate-type anionic antistatic agents, quaternary ammonium salt-type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine-type amphoteric antistatic agents, etc.), flame retardants (melamine cyanurate, hydroxides such as magnesium hydroxide and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.), etc. Two or more of these may be blended.

[0053] The fiber-reinforced thermoplastic resin filaments of the present invention can be obtained by impregnating multiple continuous reinforcing fibers with a thermoplastic resin. Examples of impregnation methods include the film method, in which a film-like thermoplastic resin is melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin; the commingling method, in which a fibrous thermoplastic resin is blended with a reinforcing fiber bundle, and then the fibrous thermoplastic resin is melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin; the powder method, in which a powdered thermoplastic resin is dispersed into the gaps between the fibers in the reinforcing fiber bundle, and then the powdered thermoplastic resin is melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin; and the pultrusion method, in which a reinforcing fiber bundle is immersed in molten thermoplastic resin and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin. The pultrusion method is preferred because it allows the production of a wide variety of fiber-reinforced thermoplastic resin filaments with various thicknesses and fiber volume contents.

[0054] Furthermore, in the fiber-reinforced thermoplastic resin filament of the present invention, it is preferable that the proportion of the reinforcing fibers whose absolute value of the orientation angle with respect to the filament axial direction, as defined by the following method, is 0 to 4 degrees is 90% or more of the total. When the proportion of the reinforcing fibers whose absolute value of the orientation angle is 0 to 4 degrees is 90% or more of the total, the strength utilization rate of the reinforcing fibers is high and an excellent reinforcing effect can be expected. 0 to 2 degrees is more preferable, and 0 to 1 degree is even more preferable. The proportion is also more preferably 93% or more, and even more preferably 95% or more.

[0055] (Method for evaluating filament orientation angle) A 20 mm length of fiber-reinforced thermoplastic resin filament sample is taken, embedded in epoxy resin "Epoquick" (registered trademark: manufactured by Buhler), and cured at room temperature for 24 hours. Thereafter, a longitudinal cross section approximately parallel to the orientation direction of the reinforcing fibers in the fiber-reinforced thermoplastic resin filament is polished to 1 / 2 of the filament thickness. Next, the polished surface is photographed at a magnification of 200x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit) (manufactured by Keyence Corporation) using the image linking function so that the entire 20 mm long longitudinal cross section is captured.

[0056] The image processing software GIMP is used to adjust the image angle of the photographed longitudinal cross-section of the fiber thermoplastic resin filament so that the filament axis direction is horizontal (0 degrees). Then, the image processing software Image J is used to perform binarization processing at a value that clearly distinguishes the outline of the reinforcing fiber. The binarized image is then used to approximate the reinforcing fiber into an ellipse, and the orientation angle (Angle) of the ellipse is determined. In order to eliminate grinding debris and noise from the binarization processing, results with a major axis (Major) value of less than 50 are deleted from the elliptical approximation results, and only the results of the reinforcing fiber ellipse approximation are extracted. The extracted results are converted to a display of the orientation angle of the reinforcing fiber from -90 degrees to +90 degrees, and the absolute value is calculated. A histogram is created to determine the orientation angle ratio. The above major axis (Major) value is an example and is easily affected by the brightness and noise of the photographed image. Therefore, a value that clearly distinguishes between reinforcing fiber and noise, etc., can be manually determined by comparing it with the binarized image.

[0057] The length of the fiber-reinforced thermoplastic resin filament of the present invention is preferably 1 m or more. By having a length of 1 m or more, the thermoplastic resin can be continuously molded, and a high reinforcing effect can be expected due to the continuous reinforcing fibers.

[0058] The thickness of the fiber-reinforced thermoplastic resin filament of the present invention is preferably 0.01 to 3 mm. If the thickness is 0.01 mm or more, the strength of the molded product obtained using the fiber-reinforced thermoplastic resin filament can be improved. 0.1 mm or more is more preferable. On the other hand, if the thickness is 3 mm or less, the flexibility of the fiber-reinforced thermoplastic resin filament can be ensured, improving handleability during molding. 2 mm or less is more preferable, and 1 mm or less is even more preferable.

[0059] The bending rigidity of the fiber-reinforced thermoplastic resin filament of the present invention is preferably 1 N m or less. If the bending rigidity is 1 N m or less, the flexibility of the filament can be ensured and handling during molding can be improved. It is more preferably 0.1 N m or less, even more preferably 0.01 N m or less, and particularly preferably 0.005 N m or less.

[0060] The fiber-reinforced thermoplastic resin filament of the present invention preferably has a void ratio of 10% or less. By having a void ratio of 10% or less, the mechanical properties of the fiber-reinforced thermoplastic resin filament can be expressed without impairing the mechanical properties of the reinforcing fiber. 5% or less is more preferable, and 2% or less is even more preferable.

[0061] (Method for Evaluating Void Ratio) The void ratio of a fiber-reinforced thermoplastic resin filament is determined by observing the cross section of the fiber-reinforced thermoplastic resin filament in the thickness direction as follows. The fiber-reinforced thermoplastic resin filament is embedded in an epoxy resin "Epoquick" (registered trademark: manufactured by Buhler) and cured at room temperature for 24 hours. The sample is then polished until the cross section of the fiber-reinforced thermoplastic resin filament in the thickness direction can be clearly observed. The polished sample is photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit) (manufactured by Keyence Corporation). The photographed range is set to a range that captures the entire cross section of the fiber-reinforced thermoplastic resin filament. In the photographed image, the total cross-sectional area of ​​the fiber-reinforced thermoplastic resin filament and the area of ​​the voids (voids) are determined, and the impregnation rate is calculated using (Equation 3). (Equation 3) Void Ratio [%] = 100 × (total area of ​​voids) / (total area of ​​fiber-reinforced thermoplastic resin filament)

[0062] The fiber-reinforced thermoplastic resin filament for 3D printers of the present invention preferably has an average value D of the dispersion parameter d [%] defined by the following method of 90% or more. By having an average value D of 90% or more, it is possible to reduce variation in the mechanical properties of the fiber-reinforced thermoplastic resin filament.

[0063] (Calculation of the average value D of the dispersion parameter d [%]) (i) A photograph of a cross section perpendicular to the axial direction of the filament is taken so that the entire cross section of the fiber reinforced thermoplastic resin filament is captured. (ii) The entire cross section image is divided into square units with a side length defined by (Equation 4). (iii) The dispersion parameter d [%] defined by (Equation 5) is calculated. (iv) The steps (i) to (iii) are repeated at multiple locations on the fiber reinforced thermoplastic resin filament for 3D printers, and the average value D of the dispersion parameter d is calculated. (Equation 4) t = 2.5a (a: fiber diameter, t: length of one side of the unit) (Equation 5) Dispersion parameter d [%] = number of units containing reinforcing fiber within the evaluation section / total number of units containing at least a portion of the filament within the evaluation section × 100

[0064] (Method for evaluating the average value D of the dispersion parameter d [%]) A sample fiber-reinforced thermoplastic resin filament is embedded in an epoxy resin "Epoquick" (registered trademark: manufactured by Buhler) and cured at room temperature for 24 hours. After that, a cross section perpendicular to the orientation direction of the reinforcing fibers in the fiber-reinforced thermoplastic resin filament is polished, and the polished surface is then photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit) (manufactured by Keyence Corporation). The photographed range is a range that captures the entire cross section of the fiber-reinforced thermoplastic resin filament. Image analysis is performed on the photographed cross-sectional photograph of the fiber-reinforced thermoplastic resin filament using Image J, and the filament is divided into mutually non-overlapping approximately square units having a side length defined by (Equation 4). These approximately square units are sequentially image analyzed, and the units containing reinforcing fibers within the approximately square units are counted, and the dispersion parameter d is calculated using (Equation 5). The image processing described above is performed by calculating the number of units containing reinforcing fibers relative to the number of units containing even a portion of a filament within the approximately square partitioned unit. While discriminant analysis is generally used for binarization, it can also be performed manually by comparing with photographs in some cases. Furthermore, reinforcing fibers contained within a unit are counted if they contain even a portion of a reinforcing fiber, and even if two or more reinforcing fibers are contained, they are counted as one unit. By photographing the polished surface of the fiber-reinforced thermoplastic resin filament at different cross-sectional observation positions, 20 or more images of the cross-sectional observation position are taken. The average value D of the dispersion parameter d of the fiber-reinforced thermoplastic resin filament obtained from each cross-sectional photograph can be calculated. From this value, the distribution of reinforcing fibers in the fiber-reinforced thermoplastic resin filament can be quantitatively evaluated.

[0065] The unit size calculated by (Equation 4) is determined by its relationship with the diameter of the observed reinforcing fiber. If the unit size is smaller than the range of (Equation 4), the dispersion parameter converges to the volume content and cannot accurately express the dispersibility. On the other hand, if it is larger than the range of (Equation 4), the value will be constant regardless of the quality of the dispersibility and will not be accurate. Therefore, it is preferable that the unit size be within the range of (Equation 5).

[0066] Furthermore, the coefficient of variation of the multiple dispersion parameters d used to calculate the average value D can be calculated using (Equation 6). When the coefficient of variation exceeds 4%, the density of the reinforcing fibers increases depending on the location in the fiber-reinforced thermoplastic resin filament. Therefore, the coefficient of variation is preferably 4% or less, and more preferably 3% or less. (Equation 6) Coefficient of variation [%] = Standard deviation of dispersion parameter d / Average value of dispersion parameter d × 100

[0067] As described above, in the fiber-reinforced thermoplastic resin filament according to one embodiment of the present invention, the absolute value of the orientation angle of the reinforcing fibers relative to the filament axial direction defined by the above-mentioned method is 0 to 4 degrees in 90% or more of the total, and since the absolute value of the orientation angle of the reinforcing fibers is 0 to 4 degrees in 90% or more of the total, a high strength utilization rate of the reinforcing fibers can be expected, and an excellent reinforcing effect can be expected. 0 to 2 degrees is more preferable, and 0 to 1 degree is even more preferable. The ratio is also more preferably 93% or more, and even more preferably 95% or more.

[0068] A molded article can be obtained by laminating one or more fiber-reinforced thermoplastic resin filaments of the present invention in any configuration and then molding them while applying heat and / or pressure as necessary.

[0069] Examples of methods for applying heat and / or pressure include a press molding method in which a molding material laminated in an arbitrary configuration is placed in a mold or on a press plate, and then the mold or press plate is closed and pressurized; an autoclave molding method in which a molding material laminated in an arbitrary configuration is placed in an autoclave and pressurized and heated; a bagging molding method in which a molding material laminated in an arbitrary configuration is wrapped in a film or the like, and heated in an oven while reducing the pressure inside and applying pressure at atmospheric pressure; a wrapping tape method in which tape is wrapped around a continuous fiber reinforced thermoplastic resin laminated in an arbitrary configuration and heated in an oven; an internal pressure molding method in which a continuous fiber reinforced thermoplastic resin laminated in an arbitrary configuration is placed in a mold and a gas or liquid is injected into a core also placed in the mold to pressurize it; and a 3D printing method in which a molding material is heated and pressurized and a three-dimensional shape is formed while melt-laminating. In particular, a 3D printing method suitable for molding complex shapes is preferably used.

[0070] The fiber-reinforced thermoplastic resin filament and molded article thereof of the present invention can take advantage of its excellent properties and be used in a variety of applications, such as aircraft parts, automobile parts, electrical and electronic parts, building materials, various containers, daily necessities, household goods, and sanitary products. The fiber-reinforced thermoplastic resin filament and molded article thereof of the present invention are particularly preferably used for aircraft engine peripheral parts, aircraft exterior parts, automobile body parts and vehicle frames, automobile engine peripheral parts, automobile underhood parts, automobile gear parts, automobile interior parts, automobile exterior parts, intake and exhaust system parts, engine cooling water system parts, automobile electrical parts, and electrical and electronic parts, which require stable mechanical properties. Specifically, the fiber-reinforced thermoplastic resin filament of the present invention and its molded article can be used for aircraft engine peripheral parts such as fan blades, aircraft-related parts such as landing gear pods, winglets, spoilers, edges, rudders, elevators, failings, and ribs, automobile body parts such as various seats, front bodies, underbodies, various pillars, various members, various frames, various beams, various supports, various rails, and various hinges, automobile engine peripheral parts such as engine covers, air intake pipes, timing belt covers, intake manifolds, filler caps, throttle bodies, and cooling fans, cooling fans, radiator tank tops and bases, cylinder head covers, oil pans, brake piping, fuel piping tubes, and exhaust gas system parts. Automotive underhood parts such as accessories, automotive gear parts such as gears, actuators, bearing retainers, bearing cages, chain guides, chain tensioners, shift lever brackets, steering lock brackets, key cylinders, door inner handles, door handle cowls, interior mirror brackets, air conditioning switches, instrument panels, console boxes, glove boxes, steering wheels, trim and other automotive interior parts, front fenders, rear fenders, fuel lids, door panels, cylinder head covers, door mirror stays, tailgate panels, license garnishes, roof rails, engine mount brackets, rear garnishes, rear spoilers, trunk lids, rocker moldings, moldings, lamp housings,Automotive exterior parts such as front grilles, mudguards, and side bumpers; intake and exhaust system parts such as air intake manifolds, intercooler inlets, turbochargers, exhaust pipe covers, inner bushings, bearing retainers, engine mounts, engine head covers, resonators, and throttle bodies; engine coolant system parts such as chain covers, thermostat housings, outlet pipes, radiator tanks, alternators, and delivery pipes; automotive electrical parts such as connectors, wire harness connectors, motor parts, lamp sockets, sensor in-vehicle switches, and combination switches; electrical and electronic parts such as generators, electric motors, transformers, current transformers, voltage regulators, rectifiers, resistors, inverters, relays, power contacts, switches, circuit breakers, switches, knife switches, multi-pole rods, motor cases, television housings, laptop computer housings and internal parts, CRT display housings, They are preferably used in electronic components such as internal parts, printer housings and internal parts, mobile terminal housings and internal parts for mobile phones, mobile personal computers, handheld mobile phones, etc., IC and LED compatible housings, capacitor base plates, fuse holders, various gears, various cases, cabinets, etc., connectors, SMT compatible connectors, card connectors, jacks, coils, coil bobbins, sensors, LED lamps, sockets, resistors, relays, relay cases, reflectors, small switches, power supply components, coil bobbins, capacitors, variable capacitor cases, optical pickup chassis, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, Si power modules and SiC power modules, semiconductors, liquid crystal displays, FDD carriages, FDD chassis, motor brush holders, transformer members, parabolic antennas, and computer-related components.

[0071] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the descriptions of these examples. The properties of each example and comparative example were evaluated according to the following methods.

[0072] 1. Static Friction Coefficient The static friction coefficient was measured by orthogonally intersecting fiber-reinforced thermoplastic resin filaments and measuring the angle at which they began to slide on an inclined surface.

[0073] Two 20 mm long fiber-reinforced thermoplastic resin filaments were taken and fixed on a rectangular plate measuring 20 mm long x 15 mm wide x 0.5 mm to 2 mm thick, with the filaments aligned in the vertical direction of the plate. The filaments were fixed so that the outer dimension was 15 mm. Two sets of rectangular plates with samples attached were prepared.

[0074] One rectangular plate with the sample attached was fixed on the tilt angle adjustment stage with the sample facing upward and the axis of the sample aligned with the tilt direction of the stage, while the remaining rectangular plate with the sample attached was placed so that the axis of the sample was perpendicular to the axis of the sample on the lower rectangular plate.

[0075] Next, in accordance with JIS P8147:2010, the tilt angle was increased at a rate of 3.0 degrees per second or less on the tilt angle adjustment stage, and the angle θ at which the upper rectangular plate with the sample began to slide was measured. This was measured five or more times. tan θ was calculated from the average angle θ of the measured values, and this value was used as the static friction coefficient of the fiber-reinforced thermoplastic resin between the filaments.

[0076] 2. Surface Roughness The roughness of the fiber-reinforced thermoplastic resin filament was measured in accordance with JIS B0601:2013 using a contact surface roughness meter (SURFCOM 480A (Tokyo Seimitsu Co., Ltd.)) as follows. After calibration using a standard piece, a level adjustment table was set on the measurement table base of the surface roughness meter. The measurement conditions selected were: measurement type Ra, measurement speed 0.3 mm / sec, cutoff value 0.8, evaluation length 4.0, slope correction linear, filter type Gaussian, and λs filter cutoff ratio 300.

[0077] A fiber-reinforced thermoplastic resin filament sample cut to a length of 30 mm was attached to the level adjustment table with the measurement direction and the fiber-reinforced thermoplastic resin filament axial direction aligned, and leveling was performed. The MEASURE switch was pressed and the measurement results of Ra in the fiber-reinforced thermoplastic resin filament axial direction were recorded. Measurements were taken at five arbitrarily selected points on the sample, and Ra was calculated from the average value.

[0078] 3. Fiber Volume Content (Vf) The volume content of the reinforcing fibers of a fiber-reinforced thermoplastic resin filament was measured and evaluated as follows. A sample was prepared by embedding a fiber-reinforced thermoplastic resin filament in epoxy resin, and the sample was polished until a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament could be clearly observed. The polished sample was photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-9500 (controller unit) / VHZ-100R (measurement unit) (manufactured by Keyence Corporation).

[0079] In the photographed cross-sectional image, the ratio of the total area of ​​the reinforcing fibers included in the total area to the total area surrounded by the outer edge of the fiber-reinforced thermoplastic resin filaments was determined, and the volume content of the reinforcing fibers was calculated using the following formula (1): (Formula 1) Volume content of reinforcing fibers [%] = 100 × (total area of ​​reinforcing fibers) / (total area of ​​fiber-reinforced thermoplastic resin filaments)

[0080] 4. Thickness The thickness of the fiber-reinforced thermoplastic resin filaments obtained in each Example and Comparative Example was measured by placing a vernier caliper perpendicular to the axial direction at 20 arbitrarily selected points on the fiber-reinforced thermoplastic resin filament, measuring the minimum distance at each point, and calculating the average value.

[0081] 5. Resin-Rich Layer Thickness The resin-rich layer thickness of the fiber-reinforced thermoplastic resin filaments obtained in each Example and Comparative Example was measured and evaluated as follows. A sample was prepared by embedding the fiber-reinforced thermoplastic resin filament in epoxy resin, and the sample was polished until the cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament could be clearly observed. The polished sample was photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-9500 (controller unit) / VHZ-100R (measurement unit) (manufactured by Keyence Corporation).

[0082] The center of gravity of the fiber-reinforced thermoplastic resin filament was determined in the photographed cross-sectional image, and an arbitrarily selected outer edge point and the center of gravity were connected by a straight line. The point where this line intersects with the interface of the resin-rich layer was connected by a straight line, and the distance was taken as the resin-rich thickness. If the interface of the resin-rich layer is not clear, the intersection point of this line with the reinforcing fiber of the core closest to the interface may be used. It was determined from the average value measured at five points on the same cross section.

[0083] 6. Impregnation The thickness direction cross section of the fiber-reinforced thermoplastic resin filament obtained in each Example and Comparative Example was observed as follows. The fiber-reinforced thermoplastic resin filament was embedded in an epoxy resin "Epoquick" (registered trademark: manufactured by Buhler) and cured at room temperature for 24 hours. The sample was then polished until the thickness direction cross section of the fiber-reinforced thermoplastic resin filament could be clearly observed. The polished sample was photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit) (manufactured by Keyence Corporation). The photographed range was set to a range that captured the entire cross section of the fiber-reinforced thermoplastic resin filament. In the photographed image, the total cross-sectional area of ​​the fiber-reinforced thermoplastic resin filament and the area of ​​the voids (voids) were determined, and the porosity was calculated using (Equation 3) (the impregnation rate is the reciprocal of the porosity). (Equation 3) Porosity [%] = 100 × (total area of ​​voids) / (total area of ​​fiber-reinforced thermoplastic resin filament)

[0084] 7. Uniformity (i) A photograph of a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament was taken so that the entire cross section of the filament was captured. (ii) The entire cross-sectional image was divided into square units with a side length defined by (Equation 4). (iii) The dispersion parameter d defined by (Equation 5) was calculated. (iv) The steps (i) to (iii) were repeated at multiple locations on the fiber-reinforced thermoplastic resin filament, and the average value D of the dispersion parameter d was calculated. (Equation 4) t = 2.5a (a: fiber diameter, t: length of one side of the unit) (Equation 5) Dispersion parameter d [%] = number of units containing reinforcing fibers within the evaluation section / total number of units containing at least a portion of a filament within the evaluation section × 100

[0085] (Evaluation method) The sample fiber-reinforced thermoplastic resin filament was embedded in epoxy resin "Epoquick" (registered trademark: manufactured by Buhler) and cured at room temperature for 24 hours. After that, the cross section perpendicular to the orientation direction of the reinforcing fibers in the fiber-reinforced thermoplastic resin filament was polished, and the polished surface was then photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit) (manufactured by Keyence Corporation). The photographed range was set to a range that captured the entire cross section of the fiber-reinforced thermoplastic resin filament. Image analysis was performed on the photographed cross-sectional photograph of the fiber-reinforced thermoplastic resin filament using Image J, and the filament was divided into mutually non-overlapping approximately square units having a side length defined by (Equation 4). These approximately square units were sequentially image analyzed, and the units containing reinforcing fibers within the approximately square units were counted, and the dispersion parameter d was calculated using (Equation 5).

[0086] The dispersion parameter d thus obtained was measured by photographing 20 or more polished surfaces while changing the cross-sectional observation position of the fiber-reinforced thermoplastic resin filament, and the average value D and the coefficient of variation of the multiple dispersion parameters d used to calculate the average value D were calculated.

[0087] 8. Straightness A 20 mm length of the fiber-reinforced thermoplastic resin filament obtained in each example and comparative example was collected, embedded in the epoxy resin "Epoquick" (registered trademark: manufactured by Buhler), and cured at room temperature for 24 hours. Thereafter, the longitudinal cross section of the fiber-reinforced thermoplastic resin filament, which was approximately parallel to the orientation direction of the reinforcing fibers, was polished to 1 / 2 of the filament thickness. Next, the polished surface was photographed at a magnification of 200x using an ultra-deep color 3D shape measuring microscope VHX-6000 (controller unit) / VH-ZST (measurement unit) (manufactured by Keyence Corporation) using the image linking function so that the entire 20 mm long longitudinal cross section was captured.

[0088] The image angle of the longitudinal cross-sectional photograph of the fiber thermoplastic resin filament was adjusted using the image processing software GIMP so that the filament axis direction was horizontal (0 degrees). Then, using the image processing software Image J, binarization processing was performed at a value that clearly distinguished the outline of the reinforcing fiber. For the binarized image, Image J was used to approximate the reinforcing fiber into an ellipse, and the orientation angle (Angle) of the ellipse was determined. In order to exclude grinding debris and noise during binarization, the results of the elliptical approximation were deleted for results with a major axis value of less than 50, and only the results of the reinforcing fiber ellipse approximation were extracted. For the extracted results, the orientation angle of the reinforcing fiber was converted to a display of -90 degrees to +90 degrees, and then the absolute value was obtained. A histogram was created to determine the percentage of a specified orientation angle.

[0089] 9. Inner / Outer Ratio When evaluating the ratio of the volume content of the reinforcing fibers in the outermost layer to the core of the fiber-reinforced thermoplastic resin filaments obtained in each Example and Comparative Example, the inner / outer ratio of the reinforcing fibers was measured and evaluated as follows.

[0090] A sample was prepared by embedding a fiber-reinforced thermoplastic resin filament in epoxy resin, and the sample was polished until a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament could be clearly observed. The polished sample was photographed at a magnification of 300x using an ultra-deep color 3D shape measuring microscope VHX-9500 (controller unit) / VHZ-100R (measurement unit) (manufactured by Keyence Corporation).

[0091] In the photographed cross-sectional image, a parallel curve was drawn from the outer edge of the fiber-reinforced thermoplastic resin filament to a position 15% inward of the filament thickness, and the volume content of the reinforcing fiber was calculated outside and inside the parallel curve using the following (Equation 1). The inner and outer ratios of the reinforcing fibers were calculated for each of the three cross sections using (Equation 2), and the arithmetic average value was obtained as the inner and outer ratio of the reinforcing fibers. (Equation 1) Volume content of reinforcing fibers [%] = 100 × (total area of ​​reinforcing fibers) / (total area of ​​fiber-reinforced thermoplastic resin filaments) (Equation 2) Inner and outer ratio of reinforcing fibers [%] = 100 × (volume content of reinforcing fibers in the outer periphery) / (volume content of reinforcing fibers in the inner part excluding the outer periphery)

[0092] 10. Bending Rigidity The bending rigidity of the fiber-reinforced thermoplastic resin filaments obtained in each of the Examples and Comparative Examples was calculated using the following formula (8): (Formula 8) Bending Rigidity = E × I

[0093] Here, E is the bending modulus of the fiber-reinforced thermoplastic resin filament, and I is the second moment of area.

[0094] The flexural modulus of the fiber-reinforced thermoplastic resin filament was measured in accordance with JIS K7074 (2012). The measurement was performed by a bending test along the axial direction of the filament.

[0095] 11. Handling Ease The handling ease of the fiber-reinforced thermoplastic resin filaments obtained in each Example and Comparative Example was evaluated by winding the fiber-reinforced thermoplastic resin filaments around a roll with an inner diameter of 150 mm and evaluating whether the wound fiber-reinforced thermoplastic resin filaments were bent or sagged, with ◯ being considered acceptable. ◯: No bends or sagging ×: Bends or sagging

[0096] 12. Modeling ability using a 3D printer (1) Modeling ability of circular cross-section filaments The circular cross-section fiber reinforced thermoplastic resin filaments obtained in each example and comparative example were visually confirmed to have good adhesion when modeled at a melting point of the thermoplastic resin used in the filament +30 ° C. using a commercially available FDM 3D printer (Ultimaker S5 manufactured by Ultimaker). The evaluation was performed on the following two levels, with ◯ being a pass. The nozzle of the 3D printer was a commercially available one, and the diameter of the tip outlet was modified to the thickness of the fiber reinforced thermoplastic resin filament obtained in each example and comparative example +0.1 mm. ◯ (Good): The adhesion between the filaments after modeling is high, and the gaps between the filaments are almost invisible. × (Bad): The adhesion between the filaments after modeling is poor, and the gaps between the filaments are clearly visible.

[0097] (2) Formability of rectangular cross-section filaments Fiber-reinforced thermoplastic resin filaments with rectangular cross-sections are laser-heated using a device similar to an AFP device, and the filaments are pressed with a pressure roller at a temperature 30°C above the melting point of the thermoplastic resin used in the filaments to form a shape. The adhesion between the filaments is visually confirmed. Evaluation is made on the following two levels, with ◯ being considered a pass. ◯ (Good): The adhesion between the filaments after forming is high, and the gaps between the filaments are almost invisible. × (Bad): The adhesion between the filaments after forming is poor, and the gaps between the filaments are clearly visible.

[0098] 13. Processability with 3D Printers (1) Processability of Circular Cross-Section Filaments The fiber-reinforced thermoplastic resin filaments obtained in each example and comparative example were used in a commercially available FDM 3D printer (Ultimaker S5 manufactured by Ultimaker) to form a 2 m long filament at a temperature of 30 ° C + the melting point of the thermoplastic resin used in the filament. It was confirmed whether clogging occurred. The above test was repeated 20 times and evaluated in the following two stages, with ◯ being a pass. The nozzle of the 3D printer was a commercially available one, and additional processing was performed so that the diameter of the tip outlet was the thickness of the fiber-reinforced thermoplastic resin filament obtained in each example and comparative example + 0.1 mm. ◯ (Good): Number of clogging occurrences was 0 to 2 times × (Bad): Number of clogging occurrences was 3 or more times

[0099] (2) Processability of rectangular cross-section filaments Fiber-reinforced thermoplastic resin filaments with rectangular cross-sections were laser-heated in a device similar to an AFP device, and the filaments were pressed with a pressure roller at a temperature 30°C above the melting point of the thermoplastic resin used in the filaments to form a 10m length. It was confirmed whether slippage occurred on the compaction roller. The above test was repeated 20 times and evaluated on the following two levels, with ◯ being considered a pass. ◯ (Good): Slippage was 10mm or less when a 10m length was formed. × (Bad): Slippage was 10mm or more when a 10m length was formed.

[0100] [Raw Materials] In the examples and comparative examples, the raw materials used were as follows.

[0101] (Carbon fiber bundle) Carbon fiber 1: Toray Industries, Inc. "Torayca (registered trademark)" T800-6K Carbon fiber 2: Toray Industries, Inc. "Torayca (registered trademark)" T700-12K Carbon fiber 3: Toray Industries, Inc. "Torayca (registered trademark)" T300-1K

[0102] (Thermoplastic resins) Thermoplastic resin 1: Polyamide (PA6) resin "Alamin (registered trademark)" manufactured by Toray Industries, Inc. Thermoplastic resin 2: Polyphenylene sulfide (PPS) resin "Torelina (registered trademark)" manufactured by Toray Industries, Inc. Thermoplastic resin 3: Polycarbonate (PC) resin "SD Polyca (registered trademark)" manufactured by Sumitomo Bakelite Co., Ltd. Filler 1: Filler beads USB-0020L manufactured by Unitika Ltd., particle size 0 to 20 μm Filler 2: Spherical alumina DAM-20 manufactured by Denka Co., Ltd., particle size (d50) 24.6 μm Filler 3: Spherical alumina DAM-05 manufactured by Denka Co., Ltd., particle size (d50) 6.8 μm

[0103] Example 1 One bobbin wound with carbon fiber 1 was prepared, and a carbon fiber bundle was continuously fed from each bobbin through a yarn guide. The continuously fed carbon fiber bundle was impregnated in an impregnation die with thermoplastic resin 1 supplied in a fixed amount from a filled feeder. The carbon fiber impregnated in the impregnation die was continuously pulled out from the nozzle of the impregnation die using a take-up roll at a pulling speed of 1 m / min. The pulled carbon fiber bundle passed through a cooling die to cool and solidify the thermoplastic resin 1, and was then wound onto a winder as the core of a fiber-reinforced thermoplastic resin filament.

[0104] The core of the fiber-reinforced thermoplastic resin filament was fed through a yarn guide, and in a coating die, thermoplastic resin 1 supplied in a fixed quantity from a filled feeder was applied. The fiber-reinforced thermoplastic resin filament having a resin layer formed around the core in the coating die was continuously pulled out from the nozzle of the coating die using a take-up roll at a pulling speed of 5 m / min. The pulled fiber-reinforced thermoplastic resin filament passed through a cooling die, where the thermoplastic resin 1 was cooled and solidified, and was wound on a winder as a fiber-reinforced thermoplastic resin filament having a resin layer on the outer periphery.

[0105] The obtained fiber-reinforced thermoplastic resin filament for 3D printers had a circular cross-sectional shape and the reinforcing fibers were arranged in one direction.

[0106] The characteristics and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and it was excellent in friction coefficient, surface roughness Ra, handleability and shaping ability, process passability, and straightness of reinforcing fibers.

[0107] [Example 2] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 1, except that carbon fiber 2 was used and the fiber volume content and cross-sectional shape of the filament were changed to a rectangular shape. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament was excellent in friction coefficient, surface roughness Ra, handleability, and straightness.

[0108] [Example 3] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 1, except that thermoplastic resin 2 was used as the thermoplastic resin. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament had excellent coefficient of friction, surface roughness Ra, handleability and shaping ability, processability, and straightness of the reinforcing fibers.

[0109] [Example 4] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 1, except that thermoplastic resin 3 was used as the thermoplastic resin. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament had excellent coefficient of friction, surface roughness Ra, handleability and shapeability, processability, and straightness of the reinforcing fibers.

[0110] [Example 5] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 1, except that filler 1 was mixed with thermoplastic resin 1 supplied in a fixed amount from a filled feeder. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament had excellent coefficient of friction, surface roughness Ra, handleability and shaping ability, processability, and straightness of the reinforcing fibers.

[0111] Comparative Example 1: One bobbin wound with carbon fiber 1 was prepared, and a carbon fiber bundle was continuously fed from each bobbin through a yarn guide. The continuously fed carbon fiber bundle was impregnated with thermoplastic resin 1, which was supplied in a fixed amount from a filled feeder, in an impregnation die. The carbon fiber impregnated in the impregnation die was continuously pulled from the nozzle of the impregnation die using a take-up roll at a pulling speed of 1 m / min. The pulled carbon fiber bundle passed through a cooling die, where the thermoplastic resin 1 was cooled and solidified, and the pulled carbon fiber bundle was wound on a winder as a continuous fiber-reinforced thermoplastic resin filament for 3D printers. The obtained fiber-reinforced thermoplastic resin filament for 3D printers had a circular cross-sectional shape, and the reinforcing fibers were aligned in one direction. The results are shown in Table 1. Although the handleability, porosity, uniformity of the reinforcing fibers, straightness of the reinforcing fibers, and shapeability were excellent, the friction coefficient, surface roughness Ra, and process passability were poor.

[0112] [Example 6] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Comparative Example 1, except that the fiber volume content and the thermoplastic resin 1 supplied in a fixed quantity from the filled feeder were mixed with filler 2. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament was excellent in terms of friction coefficient, surface roughness Ra, handleability and shaping ability, processability, and straightness of the reinforcing fibers.

[0113] [Comparative Example 2] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Comparative Example 1, except that the fiber volume content and the thermoplastic resin were changed to Thermoplastic Resin 2. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1. Although the filament was excellent in handleability, porosity, uniformity of the reinforcing fibers, straightness of the reinforcing fibers, and shapeability, it was inferior in friction coefficient, surface roughness Ra, and process passability.

[0114] 8, the filament produced in Example 2 was pulled out from the nozzle of the impregnation die 18, and then the filament was threaded through the axial hole 20 of the bobbin 19 around which the carbon fiber 3 used as the covering yarn was wound. At this time, the bobbin was installed so as to be rotatable around its axis.

[0115] After the filament passed through the axial hole 20, the filament was heated by an infrared heater 21 to melt the surface of the filament, and the covering yarn was wound around the filament surface while being attached. At this time, the bobbin was rotated at a speed of 20 times / min relative to the filament speed of 1 m / min, and the covering yarn was wound at a twist rate of 20 T / min.

[0116] The characteristics and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and it was excellent in friction coefficient, surface roughness Ra, handleability and shaping ability, process passability, and straightness of reinforcing fibers.

[0117] [Comparative Example 3] In the filament produced in Example 7, immediately after winding the covering yarn, the surface was further heated with an infrared heater, and filler 2 was scattered there to adhere to the filament surface layer. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1. Although it was excellent in handleability, porosity, uniformity of reinforcing fibers, straightness of reinforcing fibers, shapeability, surface roughness, and surface roughness Ra, it was poor in friction coefficient and process passability.

[0118] [Example 8] A filament wound with a covering yarn was obtained in the same manner as in Example 7, except that the covering yarn was wound around the filament by setting the bobbin rotation speed to 3 times / min and the twist rate to 3 T / min relative to a filament speed of 1 m / min. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament was excellent in terms of friction coefficient, surface roughness Ra, handleability and shaping ability, processability, and straightness of the reinforcing fiber.

[0119] [Example 9] In the filament produced in Example 7, immediately after winding the covering yarn, the surface was further heated with an infrared heater, and filler 3 was scattered there to adhere to the filament surface layer. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and it was excellent in handleability, porosity, uniformity of reinforcing fibers, straightness of reinforcing fibers, shapeability, surface roughness, surface roughness Ra, friction coefficient, and process passability.

[0120] [Example 10] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 1, except that the thickness of the resin-rich layer of the thermoplastic resin was reduced. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and it was excellent in friction coefficient, surface roughness Ra, handleability and shaping ability, process passability, and straightness of the reinforcing fiber. It was also excellent in passability.

[0121] [Example 11] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 2, except that the thickness of the resin-rich layer of the thermoplastic resin was reduced. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament had excellent coefficient of friction, surface roughness Ra, handleability and shaping ability, processability, and straightness of the reinforcing fibers.

[0122] [Example 12] A fiber-reinforced thermoplastic resin filament was produced in the same manner as in Example 3, except that the thickness of the resin-rich layer of the thermoplastic resin was reduced. The properties and evaluation results of the obtained fiber-reinforced thermoplastic resin filament are as shown in Table 1, and the filament had excellent coefficient of friction, surface roughness Ra, handleability and shaping ability, processability, and straightness of the reinforcing fibers.

[0123] [Rule 26 amendment 03.03.2023]

[0124] The fiber-reinforced thermoplastic resin filament according to the present invention can be molded into a desired shape by any method, such as press molding or 3D printing. 3D printing, in particular, is required to achieve both high reinforcement effect and ease of handling during molding, and is therefore suitable as a molding method for the fiber-reinforced thermoplastic resin filament according to the present invention. Molded products obtained by molding the fiber-reinforced thermoplastic resin filament according to the present invention are useful for automotive applications such as aircraft engine peripheral parts, aircraft interior parts, aircraft exterior parts, vehicle frames, automobile engine peripheral parts, automobile underhood parts, automobile gear parts, automobile interior parts, automobile exterior parts, intake and exhaust system parts, engine cooling water system parts, and automotive electrical parts, as well as electrical and electronic component applications such as LED reflectors and SMT connectors.

[0125] 1 Circular cross-section filament 2 Elliptical cross-section filament 3 Modified cross-section filament (1) 4 Modified cross-section filament (2) 5 Rectangular plate with sample (top) 6, 7, 9, 10 Fiber-reinforced thermoplastic resin filament 8 Rectangular plate with sample (bottom) 11 Tilt angle adjustment stage 12, 17 Filament 13 Thickness 14 Outer edge 15 Parallel curve moved inward from the outer edge by a distance of 15% of the thickness 16 Outer periphery 18 Impregnation die 19 Bobbin 20 Axial hole 21 Infrared heater

Claims

1. A fiber-reinforced thermoplastic resin filament comprising a plurality of continuous reinforcing fibers impregnated with at least one selected from the group consisting of polyphenylene sulfide resin (PPS), polyarylene ether ketone resin (PAEK), polyamide (PA), polycarbonate (PC), polyetherimide resin (PEI), polyethersulfone resin (PES), and liquid crystal polymer resin (LCP), wherein in a cross section perpendicular to the axial direction of the fiber-reinforced thermoplastic resin filament, the inner / outer ratio of reinforcing fibers, defined as the ratio of the volume content of reinforcing fibers in the outer periphery extending from the outer edge to 15% inside the filament thickness to the volume content of reinforcing fibers in the inner portion excluding the outer periphery, is 0 to 90%, and the surface static friction coefficient is 0.20 to 0.

80.

2. The fiber-reinforced thermoplastic resin filament according to claim 1, wherein the static friction coefficient is 0.20 to 0.

40.

3. The fiber-reinforced thermoplastic resin filament according to claim 1, wherein the inner / outer ratio is 10 to 60%.

4. The fiber-reinforced thermoplastic resin filament according to claim 1, having a surface roughness Ra of 0.50 to 20 μm.

5. The fiber-reinforced thermoplastic resin filament according to claim 1, wherein the average value D of the dispersion parameter d [%] measured by the following methods (i) to (iv) is 90% or more. (i) A photograph of a cross section perpendicular to the axial direction of the filament is taken so that the entire cross section of the fiber-reinforced thermoplastic resin filament is captured. (ii) The entire cross-sectional image is divided into square units having a side length defined by (Equation 4). (iii) The dispersion parameter d [%] defined by (Equation 5) is calculated. (iv) The steps (i) to (iii) are repeated at multiple locations on the fiber-reinforced thermoplastic resin filament to calculate the average value D of the dispersion parameter d [%]. (Equation 4) t = 2.5a (a: fiber diameter, t: side length of unit) (Equation 5) Dispersion parameter d [%] = number of units containing reinforcing fibers within the evaluation section / total number of units containing at least a portion of a filament within the evaluation section × 100 6. A fiber-reinforced thermoplastic resin filament for 3D printers as described in claim 5, wherein the coefficient of variation of the multiple dispersion parameters d used to calculate the average value D is 4% or less.

7. A fiber-reinforced thermoplastic resin filament according to claim 1, wherein the reinforcing fibers of the fiber-reinforced thermoplastic resin filament are wrapped with fibers twisted at 50 T / m or less as covering yarns.

8. The fiber-reinforced thermoplastic resin filament according to claim 7, having a surface roughness Ra of 10 to 20 μm.

9. The fiber reinforced thermoplastic resin filament of claim 1, wherein the thermoplastic resin contains a filler.

10. A fiber-reinforced thermoplastic resin filament according to claim 1, wherein the inner / outer ratio is 15 to 80%, the thickness is 0.01 to 3 mm, and the filament length is 1 m or more.

11. The fiber-reinforced thermoplastic resin filament according to claim 1, having a void content of 10% or less.

12. The fiber-reinforced thermoplastic resin filament according to claim 1, wherein the reinforcing fibers are carbon fibers.

13. A molded product obtained using the fiber-reinforced thermoplastic resin filament described in claim 1.