Method for producing fiber-reinforced resin composite

Abstract

To provide a method for producing a fiber-reinforced resin composite capable of obtaining a fiber-reinforced resin composite excellent in bending strength and high in complete roundness.SOLUTION: In the present invention, a method for producing a fiber-reinforced resin composite is provided, which at least includes a drawing step in which a bundle of reinforcing fibers is continuously run through a molten thermoplastic resin, passed through a nozzle to impregnate the resin into the reinforcing fiber bundle, and drawn out. In the drawing step, the resin temperature of the molten thermoplastic resin is set such that the MFR is 80 g / 10 min or higher, and the temperature is set such that the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle exit is 5 g / 10 min to 50 g / 10 min, and a water cooling tank is provided at the nozzle exit for cooling.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fiber-reinforced resin composite, and more particularly to a method for producing a fiber-reinforced resin composite that is excellent in bending strength and has high circularity. [Background technology]

[0002] Fiber-reinforced plastic (FRP) articles, in which reinforcing fibers are bound with synthetic resin, are strong and lightweight and are used as alternatives to metal articles in a wide range of fields, including automotive parts, electronic components, agricultural and forestry materials, building materials, furniture, etc. One product that uses this FRP technology is glass roving or other long-fiber bundles as reinforcing fibers, and pipes, rods, linear objects, etc., which have a resin matrix, have long been used in various industrial fields.

[0003] In recent years, various needs have arisen, one of which is the demand for fiber-reinforced resin composites with improved circularity. For example, Patent Document 1 discloses a technique for improving circularity by passing a fiber-reinforced resin composite obtained by drawing it out from a die (hereinafter also referred to as a "nozzle"), which is the outlet of a fiber-opening impregnation tank, through a shaping cooling slit so that the temperature falls within the crystallization temperature range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-329225 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to improve impregnation, it is necessary to increase the temperature of the impregnation bath to reduce the resin viscosity, which inevitably increases the nozzle temperature in conventional techniques. Therefore, even when cooling is performed after pulling out from the nozzle, it takes time to cool the fiber-reinforced resin composite to the crystallization temperature range, making it difficult to improve roundness, especially when the take-up speed is high. Furthermore, the above-mentioned Patent Document 1 and others only target crystalline resins and do not specify a temperature range after cooling for amorphous resins.

[0006] In view of the above circumstances, the present invention has as its main object to provide a method for producing a fiber-reinforced resin composite that can produce a fiber-reinforced resin composite having excellent bending strength and high circularity. [Means for solving the problem]

[0007] As a result of intensive experimental investigations, the inventors of the present application have discovered a method for manufacturing a fiber-reinforced resin composite that, by focusing particularly on the withdrawal process, produces a fiber-reinforced resin composite that has excellent bending strength and high circularity, and have thereby completed the present invention.

[0008] The present invention first provides a method for producing a fiber-reinforced resin composite, which includes at least a take-up step of continuously running a reinforcing fiber bundle through a molten thermoplastic resin and passing the resin-impregnated reinforcing fiber bundle through a nozzle to take it up, wherein in the take-up step, the resin temperature in the molten thermoplastic resin is set to a temperature such that the MFR is 80 g / 10 min or more, and the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet is set to a temperature such that the MFR is 5 g / 10 min to 50 g / 10 min, and a water-cooled bath is provided from the nozzle outlet to perform cooling. In the present invention, a water cooling bath may be provided within 200 mm from the nozzle outlet in the taking-up step. Furthermore, in the present invention, in the taking-up step, the temperature may be controlled so that the MFR of the molten resin contained in the resin-impregnated fiber bundle when passing through the nozzle is 5 g / 10 min to 30 g / 10 min. In addition, the fibers constituting the reinforcing fiber bundles and / or the thermoplastic resin may be biodegradable. [Effects of the Invention]

[0009] According to the present invention, a fiber-reinforced resin composite having excellent bending strength and high roundness can be obtained. The effects described here are not necessarily limited to those described herein, and may be any of the effects described in this specification. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a schematic structure of a fiber-reinforced resin composite 1. FIG. [Figure 2] 1 is a graph substituting a drawing showing an example of a calibration curve for polycarbonate. [Figure 3] 1 is a graph substituting a drawing showing an example of a calibration curve for nylon 6. [Figure 4] 1 is a diagram schematically illustrating an outline of a method for producing a fiber-reinforced resin composite 1 according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described below is merely an example of a typical embodiment of the present invention, and the scope of the present invention should not be construed as being narrow.

[0012] 1. Fiber-reinforced resin composite 1 1A and 1B are diagrams schematically illustrating the structure of a fiber-reinforced resin composite 1. The fiber-reinforced resin composite 1 (hereinafter also simply referred to as "composite 1") includes at least a reinforcing layer 11 (see FIG. 1A) and, as necessary, one or more coating layers 12 (see FIG. 1B).

[0013] The complex 1 is rod-shaped, and the term "rod-shaped" as used herein specifically refers to a shape whose cross section is a flat shape such as a circle or an oval.

[0014] <Flatness (measured by outer diameter)> In the present invention, the flattening ratio determined by measuring the outer diameter is a value determined as follows. First, the fiber-reinforced resin composite was measured at five random points using a thickness gauge (Mitutoyo, 547-301A) to determine the major and minor diameters. Next, the oblateness was calculated using the following formula (1), and the average value was used as the measured value. Oblateness = (major diameter - minor diameter) / ((major diameter + minor diameter) / 2) (1)

[0015] In the present invention, the flatness is preferably less than 10%, more preferably less than 7%, and even more preferably less than 5%.

[0016] <Bending strength measured by three-point bending test> Measurement was performed under the following conditions, and the average value was taken as the measured value. The test was conducted on five samples (N=5) cut to twice the distance between supports. The distance between supports was 20 times the outer diameter of the fiber-reinforced resin composite, and the test speed was 5.0 mm / min. Under these conditions, the three-point bending test was conducted, and the average value of N=5 was taken as the measured value.

[0017] Regarding the bending strength of the composite 1, there is a correlation with the impregnation property when the raw materials and the volume content of the reinforcing fibers are the same, and composite 1 with high impregnation property tends to have high bending strength, while composite 1 with low impregnation property tends to have low bending strength.

[0018] In the present invention, the bending strength is preferably 600 MPa or more.

[0019] Since composite 1 has excellent bending strength and roundness, it is expected to be used more widely than ever before as an alternative material to metal articles in a wide range of fields, such as automotive parts, electronic parts, agricultural and forestry materials, building materials, and furniture. Each layer will be described in detail below.

[0020] (1) Reinforcement layer 11 1, the reinforcing layer 11 is a layer formed of reinforcing fiber bundles 112 impregnated with a thermoplastic resin 111. Reinforcing fibers impregnated with a thermoplastic resin are generally called fiber reinforced thermoplastic resin (FRTP).

[0021] <Reinforcing fiber bundle 112> The reinforcing fiber bundles 112 used in the present invention are preferably substrates in the form of continuous long fiber bundles or fiber braids (for example, woven fabrics, knitted fabrics, braided fabrics, etc.). By using these, continuous impregnation and continuous formation of the coating layer 12 can be ensured, enabling the production of fiber-reinforced resin composites with excellent productivity.

[0022] Examples of fibers that can be used to form the reinforcing fiber bundles 112 include organic fibers such as olefin fibers, aramid fibers, and liquid crystal polyester (LCP) fibers; glass fibers; inorganic fibers such as carbon fibers; ceramic fibers such as Tyranno fibers; metal fibers such as boron fibers, copper fibers, and stainless steel fibers; amorphous fibers; natural fibers such as kenaf fibers; and polyamide fibers such as nylon 6 and nylon 66. Also, in the present invention, blends of these fibers can also be used. Furthermore, in the present invention, these fibers may be used alone or in combination of two or more.

[0023] In the present invention, it is particularly preferable to use glass fibers and / or carbon fibers among these.

[0024] Furthermore, in the present invention, it is preferable to use biodegradable fibers. This can contribute to the achievement of the SDGs. Examples of biodegradable fibers include the above-mentioned natural fibers; biodegradable polyester fibers such as polycaprolactone, polyethylene succinate, polybutylene succinate, polyethylene adipate, polybutylene adipate, polyethylene succinate-adipate copolymer, polylactic acid, and polyester fibers in which these are used as the main component and other dicarboxylic acids and / or glycols are copolymerized. Furthermore, in the present invention, these fibers may be used alone or in combination.

[0025] Examples of glass fibers that can be used include long fibers such as glass fiber monofilaments, glass fiber strands, glass fiber rovings, and glass fiber yarns. In the present invention, it is particularly preferable to use glass fiber rovings and / or glass fiber yarns. Also, glass fiber braids such as glass fiber woven fabrics, glass fiber braids, and glass fiber knitted fabrics may be used.

[0026] The glass fiber may be surface-treated with a surface treatment agent such as an epoxy silane coupling agent or an acrylic silane coupling agent. Examples of the glass composition of the glass fiber include E-glass, S-glass, and C-glass. Degradable or biosoluble glass fibers may also be used. Among these, E-glass is particularly preferred in the present invention. The cross section of the glass fiber monofilament may be a flat shape, such as a substantially circular or elliptical shape.

[0027] The reinforcing fiber bundle 112 can be prepared in advance as needed by a conventionally known method such as weaving, braiding, or knitting to a desired length, or a long one can be wound up on a roll and used. The reinforcing fiber bundle 112 can also be heated to improve the impregnation of the resin into the reinforcing fibers or to remove moisture from the reinforcing fibers.

[0028] The volume content of the reinforcing fibers (bundles) 112 is preferably 20% to 80% of the entire reinforcing layer 11, and more preferably 40% to 60%. If the volume content is lower than 20%, the reinforcing effect of the reinforcing fibers is reduced. Conversely, if the volume content is higher than 80%, the amount of resin is too small, which adversely affects bending strength.

[0029] <Thermoplastic resin 111 used in the reinforcing layer 11> Examples of the thermoplastic resin 111 used as the matrix resin in the present invention include polyolefin resins such as polypropylene (PP), polyethylene (PE), and polyisobutylene (PB); polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PENp), and liquid crystal polyester (LCP); styrene resins such as polystyrene (PS), acrylonitrile-styrene resin (AS), acrylonitrile-butadiene-styrene resin (ABS), acrylonitrile-acrylic-styrene resin (AAS), and acrylonitrile-ethylene propylene rubber-styrene (AES); urethane resin, nylon 6, and the like. Other examples include polyvinyl alcohol (PVA), polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polyphenylene ether (PPE), modified PPE, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone (PSU), modified PSU, polyethersulfone (PES), polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyarylate (PAR), polyethernitrile (PEN), etc. In the present invention, these may be used alone or in combination of two or more.

[0030] In the present invention, it is particularly preferable to use polycarbonate and / or nylon 6 among these.

[0031] Furthermore, in the present invention, it is preferable to use a biodegradable thermoplastic resin. This can contribute to the achievement of the SDGs. Examples of biodegradable thermoplastic resins include polylactic acid (PLA), polyglycolic acid (PGA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polybutylene adipate / terephthalate (PBAT), polyethylene terephthalate succinate (PETS), polybutylene succinate adipate (PBSA), polybutylene succinate (PBS), poly(ε-caprolactone) (PCL), polyamide 4 (PA4), and poly(3-hydroxybutanoic acid) (P(3HB)). Furthermore, in the present invention, these may be used alone or in combination of two or more.

[0032] In addition, to the above-mentioned thermoplastic resin, one or more of various additives may be added as needed to obtain desired physical properties. Specific examples of additives that can be added include ultraviolet absorbers, antioxidants, stabilizers such as heat stabilizers, pigments, dyes, lubricants, flame retardants, mold release agents, and sliding improvers. Furthermore, to further enhance biodegradability, biodegradable modifiers and the like may be added.

[0033] <Twist in reinforcement layer 11> In the present invention, the reinforcing layer 11 may be twisted or untwisted. If twisted, it may be unidirectional (S twist or Z twist) or SZ twist.

[0034] Regarding the position where twisting is performed, if there is no coating layer 12, it may be performed at any position between the water-cooling bath 50 and the take-up device 60, which will be described later. Note that twisting and take-up may be performed simultaneously, as in a rotary take-up device, but twisting cannot be performed after the take-up device 60. If there is a coating layer 12, it may be performed at any position between the water-cooling bath 50 and the take-up device 60, which will be described later (or take-up and twisting are performed at the same position), but in this case, the coating step of forming the coating layer 12 will be performed after the take-up device 60. Note that if twisting is not performed, the coating step may be performed anywhere after the nozzle outlet. Furthermore, there are no particular limitations on the method of twisting.

[0035] (2) Covering layer 12 The coating layer 12 is not an essential component, but is one or more layers that coat the outermost surface of the reinforcing layer 11 with a thermoplastic resin. Although Fig. 1B depicts a case where there is one coating layer 12, in the present invention, there may be two or more coating layers 12. Examples of a structure where there are two or more coating layers 12 include a structure in which part or all of a first coating layer 12 that covers the reinforcing layer 11 is covered in turn with second or more coating layers 12.

[0036] <Thermoplastic Resin Used in Coating Layer 12> The thermoplastic resin used for the coating layer 12 may be, for example, the thermoplastic resin 111 as the matrix resin described above.

[0037] In the present invention, it is particularly preferable to use polycarbonate and / or polyolefin resins among these. Furthermore, biodegradable thermoplastic resins may also be used.

[0038] Furthermore, in the present invention, it is preferable that the thermoplastic resin coating the outermost layer (the thermoplastic resin used for the coating layer 12) has a melting start temperature equal to or lower than the melting start temperature of the thermoplastic resin 111 (the thermoplastic resin 111 used for the reinforcing layer 11) impregnated into the reinforcing fiber bundles 112, or that the melting start temperature of the thermoplastic resin coating the outermost layer is 200°C or lower. If the melting start temperature of the thermoplastic resin used for the coating layer 12 is higher than the melting start temperature of the matrix resin, the composite of the reinforcing fibers and the thermoplastic resin will melt during coating, adversely affecting the physical properties. However, if the thermoplastic resin has a melting start temperature of 200°C or lower, even if it is higher than the melting start temperature of the matrix resin, cooling can be performed in a short time, so there is almost no adverse effect on the physical properties, and therefore no adverse effects will occur.

[0039] 2. Manufacturing method of fiber reinforced resin composite 1 The method for producing the composite 1 according to the present invention includes at least a take-up step (hereinafter also referred to as "step B") of continuously running a reinforcing fiber bundle 112 through a molten thermoplastic resin and passing the resin-impregnated reinforcing fiber bundle through a nozzle to take it up, and is characterized in that in the take-up step, the resin temperature in the molten thermoplastic resin is set to a temperature at which the MFR is 80 g / 10 min or more, and the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet is set to a temperature at which the MFR is 5 g / 10 min to 50 g / 10 min, and a water-cooled bath 50 is provided from the nozzle outlet to perform cooling.

[0040] The composite 1 produced by the method for producing the composite 1 according to the present invention has excellent bending strength and roundness.

[0041] 4 is a diagram schematically illustrating an outline of a method for producing a fiber-reinforced resin composite 1 according to the present invention. The method for producing a composite 1 according to the present invention includes at least step B. If necessary, other steps may also be performed. Note that the composite 1 produced below is a production method for a case where the composite 1 does not have a coating layer 12 (see A in FIG. 1).

[0042] The composite 1 having the coating layer 12 can be manufactured by a conventionally known method. The coating step of forming the coating layer 12 may be performed between the nozzle and the water-cooled bath 50, or may be performed after the outer diameter is determined by the water-cooled bath 50. When the coating layer 12 is formed from the nozzle outlet, it may be formed at any step between the nozzle outlet and the take-up device 60. Each step will be described in detail below.

[0043] (1) Process A This step is not essential, but may be carried out in the method for producing the composite 1 according to the present invention. Step A is a step of making the reinforcing fiber bundles 112 ready to be taken up. More specifically, a required number of reinforcing fiber bundles 112 (see also "10" in FIG. 4) are pulled out from the creel 20, and if necessary, the reinforcing fiber bundles 112 are passed through a preheating device (not shown) that has not yet been heated via a tension adjusting means, and the group of reinforcing fiber bundles 112 is pulled out from the impregnation tank 40 and passes through a cooling tank (not shown) that is not filled with cooling water, so that the group of reinforcing fiber bundles 112 can be taken up by the take-up device 60.

[0044] (2) Process B This step is an essential step. In step B, as described above, the reinforcing fiber bundle 112 is continuously run through the molten thermoplastic resin, and the resin-impregnated reinforcing fiber bundle is passed through a nozzle and taken up.

[0045] More specifically, while the group of reinforcing fiber bundles 112 is taken up at a predetermined speed via the creel 20, a predetermined tension is applied to each reinforcing fiber bundle 112 via a tension adjusting means, the preheating device is heated to heat the reinforcing fiber bundles 112, the melt extruder 30 is driven, a thermoplastic resin is supplied to the crosshead die, each reinforcing fiber bundle 112 is brought into contact with the molten thermoplastic resin in the impregnation tank 40, each reinforcing fiber bundle 112 is impregnated with the thermoplastic resin, and the reinforcing fiber bundles 112 (also referred to as "long fiber reinforcing fiber bundles 112") are extrusion coated as a linear object at subatmospheric pressure or under pressure while adjusting the diameter with a draw in the impregnation tank 40. The linear object is then cooled in a water-cooled tank 50 and taken up by a take-up device 60.

[0046] The volume content of the reinforcing fibers (bundles) relative to the entire reinforcing layer 11 produced in steps A and B can be freely set by a person skilled in the art using conventionally known methods, but in the present invention, it is preferably 20% or more and 80% or less, and more preferably 40% or more and 60% or less.

[0047] In order to improve the impregnation property, a round bar for opening fibers may be introduced into the impregnation tank 40 and the fibers may be drawn off while being squeezed.

[0048] Furthermore, the reinforcing fiber bundles 112 inside the impregnation tank 40 or before entering the impregnation tank 40 may be purged with an inert gas such as nitrogen or argon. Purging with an inert gas can suppress oxidation, hydrolysis, etc. of the thermoplastic resin.

[0049] Furthermore, the reinforcing fiber bundles 112 may be heated using an infrared heater or the like before entering the impregnation tank 40. By preheating the reinforcing fiber bundles 112, a decrease in the temperature of the molten resin in the impregnation tank 40 can be suppressed, and the impregnation property can be improved.

[0050] Although not shown, the reinforcing fiber bundles 112 may be twisted after being extrusion coated as a linear object. The reinforcing fiber bundles 112 impregnated with the twisted thermoplastic resin are cooled to produce the reinforcing layer 11. If no twist is imparted, the reinforcing fiber bundles 112 impregnated with the untwisted thermoplastic resin are cooled to produce the reinforcing layer 11. Specifically, the linear object is cooled and shaped by one or more methods selected from the group consisting of air cooling, water cooling, and mist spraying, to produce the reinforcing layer 11.

[0051] In the present invention, when the reinforcing fiber bundle 112 is continuously run through a molten thermoplastic resin and the resin-impregnated reinforcing fiber bundle is passed through a nozzle and taken up, the resin temperature in the molten thermoplastic resin is set to a temperature at which the MFR is 80 g / 10 min or more, and the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet is set to a temperature at which the MFR is 5 g / 10 min to 50 g / 10 min, and a water-cooled bath 50 is provided from the nozzle outlet for cooling.

[0052] In conventional manufacturing methods, there is a trade-off between the resin's ability to impregnate fibers and the dimensional stability of the product. In other words, if the resin temperature is increased to increase the MFR in order to improve impregnation, it becomes difficult to improve dimensional stability. Conversely, if the resin temperature is decreased to decrease the MFR, it also becomes difficult to improve impregnation. In contrast, the present invention achieves both impregnation and dimensional stability by controlling the MFR of the resin in the impregnation tank and the MFR of the resin at the nozzle outlet.

[0053] MFR stands for "melt mass flow rate" and is a measure of the fluidity of a resin in a molten state. MFR is the rate at which a molten resin is extruded through a die of specified length and diameter under specified conditions of temperature, load, and piston position inside the plastometer cylinder, and this rate is determined as the mass extruded in a specified time. MFR is expressed in grams per 10 minutes (g / 10 min). The method for measuring MFR is specified in JIS K7210, and can be measured, for example, using a melt indexer (G-02, manufactured by Toyo Seiki Seisakusho).

[0054] In the present invention, the MFR of a resin immediately after it has left the impregnation tank or the nozzle is determined by first measuring the MFR of the resin at each temperature in advance using a load of 1.2 kg during measurement, and then measuring the temperature of the resin immediately after it has left the impregnation tank or the nozzle, thereby determining the MFR.

[0055] Specifically, as shown in FIG. 2, for polycarbonate, the MFR of the resin is measured in advance at each temperature (180°C, 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, and 320°C), and a calibration curve is prepared. The temperature at which the MFR is 80 g / 10 min or higher is then estimated, determined, and controlled based on the calibration curve. The temperature at which the MFR is 5 g / 10 min to 50 g / 10 min is also determined and controlled in a similar manner. As shown in FIG. 3, for nylon 6, the MFR of the resin is also measured in advance at each temperature (240°C, 260°C, 280°C, 300°C, and 320°C), a calibration curve is prepared, and the temperature is determined and controlled by the method described above. By setting the optimum temperature for the resin used in this manner, the effects of the present invention can be achieved.

[0056] Therefore, in the present invention, as described above, the temperature of the impregnation tank 40 is increased so that the MFR of the molten resin becomes 80 g / 10 min or more. If the MFR of the molten resin is less than 80 g / 10 min, not only will the strength of the fiber-reinforced resin composite 1 decrease due to poor impregnation, but the take-up resistance will also increase, and stable production may become impossible due to clogging with fiber fluff.

[0057] Furthermore, in the present invention, as described above, the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet is preferably in the range of 5 g / 10 min to 50 g / 10 min, and more preferably in the range of 5 g / 10 min to 30 g / 10 min. If the MFR is less than 5 g / 10 min, the take-up resistance increases, and clogging with fiber fluff may prevent stable production. On the other hand, if the MFR exceeds 50 g / 10 min, it is difficult to obtain a fiber-reinforced resin composite 1 with a small aspect ratio.

[0058] Furthermore, in order to produce a composite 1 with a small aspect ratio, it is preferable to cool the resin-impregnated fiber bundle drawn out from the nozzle by water cooling in a short time. The water cooling bath 50 is positioned at a distance from the nozzle of preferably 200 mm or less, more preferably 100 mm or less, and even more preferably 50 mm or less.

[0059] Air cooling, mist spraying, etc. may also be used in combination with water cooling. Air cooling may be performed at multiple locations rather than just one, and a flow rate of 50 L / min or more is preferred. The air slit used for air cooling comes in a variety of shapes, including ring and flat, but a ring shape is preferred as it allows for more uniform air application.

[0060] The nozzle diameter is not particularly limited as long as the cross-sectional shape is approximately circular. The nozzle length, nozzle temperature control method, etc. are not particularly limited as long as the MFR of the molten resin of the composite 1 at the nozzle outlet is within a specified range. The nozzle temperature may be controlled in multiple stages. When the production speed is high or the nozzle diameter is large, it becomes difficult to reduce the MFR of the molten resin contained in the reinforcing fiber bundle 112 as it passes through the nozzle to within the specified range unless the nozzle length is increased. On the other hand, making the nozzle longer than necessary is not preferable because it widens the temperature control range and increases the take-up resistance. The nozzle length can be, for example, 10 mm to 300 mm. [Example]

[0061] The present invention will be described in more detail below based on examples. The embodiment described below is merely a representative example of the present invention, and the scope of the present invention should not be construed as being narrow.

[0062] <Production of fiber-reinforced resin composites> [Example 1] Five pieces of 2200 tex glass fiber roving (Nitto Boseki, RS220RL-510AH) and one piece of 1150 tex glass fiber roving (Nitto Boseki, RS110QL-533AH) were placed on a stand, and the fibers were passed through an impregnation chamber. The fibers were then passed through a 130 mm long, 3.5 mm diameter temperature-controlled nozzle in the impregnation chamber, which was then attached to the impregnation chamber. An air slit was installed 10 mm from the nozzle, and a 50 cm long water-cooled bath was installed 50 mm from the nozzle. The water-cooled bath was then filled with water, and the air flow rate was adjusted to 100 L / min. While the fibers were being drawn out with a take-up device, the impregnation chamber, adjusted to a temperature with an MFR of 170 g / 10 min, was filled with polycarbonate resin (Mitsubishi Engineering Plastics, HL-8002) using an extruder. The nozzle temperature was then adjusted so that the temperature of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet was 45 g / 10 min, resulting in a fiber-reinforced resin composite with a reinforcing fiber volume content of 50%. The obtained fiber-reinforced resin composite was evaluated for flatness by measuring the outer diameter and for bending strength by measuring three-point bending, and the results are shown in Table 1 below.

[0063] [Example 2] A fiber-reinforced resin composite was obtained in the same manner as in Example 1, except that the nozzle temperature was adjusted so that the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet was 28 g / 10 min. The obtained fiber-reinforced resin composite was also evaluated for flatness by outer diameter measurement and bending strength by three-point bending measurement, as in Example 1, and the results are shown in Table 1 below.

[0064] [Example 3] A fiber-reinforced resin composite was obtained by manufacturing in the same manner as in Example 1, except that the diameter of the fiber-reinforced resin composite was set to 10 mm. The obtained fiber-reinforced resin composite was also evaluated for flattening by measuring the outer diameter and for bending strength by measuring three-point bending, in the same manner as in Example 1, and the results are shown in Table 1 below.

[0065] [Example 4] A fiber-reinforced resin composite was obtained in the same manner as in Example 1, except that the matrix resin used in the reinforcing layer was nylon 6 (A1025SR, manufactured by Unitika). The obtained fiber-reinforced resin composite was also evaluated for flattening by outer diameter measurement and bending strength by three-point bending measurement, as in Example 1, and the results are shown in Table 1 below.

[0066] [Example 5] Except for changing the distance between the nozzle and the water-cooling bath to 250 mm, a fiber-reinforced resin composite was obtained by production in the same manner as in Example 1. The obtained fiber-reinforced resin composite was also evaluated for flattening by outer diameter measurement and bending strength by three-point bending measurement in the same manner as in Example 1, and the results are shown in Table 2 below.

[0067] [Comparative Example 1] A fiber-reinforced resin composite was obtained in the same manner as in Example 1, except that the nozzle temperature was adjusted so that the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet was 62 g / 10 min. The obtained fiber-reinforced resin composite was also evaluated for flatness by measuring the outer diameter and for bending strength by measuring three-point bending, as in Example 1, and the results are shown in Table 2 below.

[0068] Comparative Example 2 A fiber-reinforced resin composite was obtained in the same manner as in Example 1, except that the nozzle temperature was adjusted so that the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet was 2 g / 10 min. The obtained fiber-reinforced resin composite was also evaluated for flatness by measuring the outer diameter and for bending strength by measuring three-point bending, as in Example 1, and the results are shown in Table 2 below.

[0069] Comparative Example 3 A fiber-reinforced resin composite was obtained in the same manner as in Example 1, except that the temperature of the resin in the impregnation tank was adjusted so that the MFR was 70 g / 10 min. The obtained fiber-reinforced resin composite was also evaluated for flattening by measuring the outer diameter and for bending strength by measuring three-point bending, in the same manner as in Example 1, and the results are shown in Table 2 below.

[0070] <Evaluation method> Each composite was subjected to the flattening test (by measuring the outer diameter) and a three-point bending test. [Flatness (measured by outer diameter)] It was calculated using the above-mentioned formula (1). The evaluation was as follows: ◎: Less than 5% ○: Less than 10% △: 10% or more ×: Sample cannot be collected and measurement is not possible

[0071] [Three-point bending test] The test was carried out according to the method described above. The evaluation was as follows: 〇: Bending strength 600MPa or more △: Bending strength less than 600 MPa ×: Sample cannot be collected and measurement is not possible

[0072] <Evaluation> The evaluation results are shown in Tables 1 and 2 below.

[0073] [Table 1]

[0074] [Table 2]

[0075] <Consideration> The composites of Examples 1 to 5 were superior in flatness compared to the composites of Comparative Examples 1 and 2. Furthermore, the composites of Examples 1 to 5 were superior in bending strength compared to the composites of Comparative Examples 2 and 3.

[0076] Therefore, it has been found that a fiber-reinforced resin composite having excellent bending strength and high roundness can be obtained by a method for producing a fiber-reinforced resin composite, which method includes at least a take-up step of continuously running a reinforcing fiber bundle through a molten thermoplastic resin and passing the resin-impregnated reinforcing fiber bundle through a nozzle and taking it up, wherein in the take-up step, the resin temperature in the molten thermoplastic resin is set to a temperature at which the MFR is 80 g / 10 min or more, and the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet is set to a temperature at which the MFR is 5 g / 10 min to 50 g / 10 min, and a water-cooled bath 50 is provided from the nozzle outlet for cooling. [Industrial Applicability]

[0077] According to the present invention, a fiber-reinforced resin composite having excellent bending strength and high circularity can be obtained. Therefore, by taking advantage of the characteristics of excellent bending strength and circularity, it is expected that the fiber-reinforced resin composite will be used more widely than ever as a material to replace metal articles in a wide range of fields, such as automobile parts, electronic parts, agricultural and forestry materials, building materials, and furniture. [Explanation of symbols]

[0078] 1: Fiber-reinforced composite 11: Reinforcement layer 111: Thermoplastic resin (matrix resin) used in the reinforcing layer 11 112,10: Reinforcing fiber bundle 12: Covering layer 20: Creel 30: Melt extruder 40: Impregnation tank 50: Cooling tank 60: Take-off device

Claims

1. A method for producing a fiber-reinforced resin composite, comprising at least a take-up step of continuously running a reinforcing fiber bundle through a molten thermoplastic resin and passing the resin-impregnated reinforcing fiber bundle through a nozzle, In the taking-up step, the resin temperature in the molten thermoplastic resin is set to a temperature at which the MFR is 80 g / 10 min or more, and the MFR of the molten resin contained in the resin-impregnated fiber bundle at the nozzle outlet is set to a temperature at which the MFR is 5 g / 10 min to 50 g / 10 min, and cooling is performed by providing a water-cooling bath from the nozzle outlet. Method for manufacturing fiber-reinforced resin composites.

2. The method for producing a fiber-reinforced resin composite according to claim 1, wherein a water cooling bath is provided between the nozzle outlet and 200 mm in the taking-up step.

3. 2. The method for producing a fiber-reinforced resin composite according to claim 1, wherein in the taking-up step, the temperature is controlled so that the MFR of the molten resin contained in the resin-impregnated fiber bundle when passing through the nozzle is 5 g / 10 min to 30 g / 10 min.

4. The method for producing a fiber-reinforced resin composite according to claim 1 , wherein the fibers constituting the reinforcing fiber bundle and / or the thermoplastic resin are biodegradable.

Images