JP6286301B2 - Method for manufacturing unidirectional fiber-reinforced tape-shaped composite material, manufacturing apparatus, and method for manufacturing random sheet using tape-shaped composite material - Google Patents

Description

The present invention reduces the void ratio while maintaining high productivity and uses a unidirectional fiber-reinforced tape-shaped composite material, a manufacturing apparatus, and the tape-shaped composite material in which reinforcing fibers and resin are mixed uniformly and homogeneously. The present invention relates to a method for manufacturing a random sheet.

FRP is a composite material in which a reinforcing fiber substrate such as carbon fiber or aramid fiber is impregnated with a thermosetting resin such as epoxy resin or urethane resin as a matrix. Since such a composite material is lightweight and high in strength, it is used, for example, in fields such as aerospace, automobiles, and sports equipment. Since the thermosetting resin is uncured and has a low viscosity, the reinforcing fiber can be easily impregnated and can be increased in strength by a curing reaction.

However, thermosetting resins have the disadvantage of being brittle and inferior in impact resistance. Further, when a thermosetting resin is made into a prepreg, it is difficult to handle due to restrictions on the usable time due to the life of the resin, and there is a problem in storage management. In addition, there is a problem that molding time is long and productivity is low, and there is a problem that recyclability and repairability are difficult.

In contrast, a composite material (FRTP) using a thermoplastic resin as a matrix has high toughness, easy prepreg storage management, and does not require a curing reaction, thus speeding up molding cycles such as injection molding and stamping molding. Is possible. Furthermore, FRTP has been put to practical use in a wide range of fields because it has many advantages over FRP, such as excellent recyclability and repair properties such as welding and repair.

However, thermosetting resins having higher mechanical properties generally have higher molecular weight and higher melt viscosity. When the melt viscosity is high, it becomes difficult to melt impregnate the reinforcing fibers and reduce the void ratio. In addition, it becomes difficult to mix the reinforcing fiber and the resin uniformly and homogeneously in the prepreg. For this reason, the low void rate FRTP in which the reinforcing fiber is impregnated with a high molecular weight / high viscosity thermoplastic resin has low productivity and high production cost. On the other hand, FRTP using a low-molecular-weight and low-viscosity thermoplastic resin that is easily impregnated has a significantly low mechanical property and has limited applications.

Therefore, various methods for efficiently producing a low void ratio FRTP using a high molecular weight / high viscosity thermoplastic resin with good impregnation have been proposed as follows. 1) A method of impregnating a continuous fiber bundle with a solution diluted with a solvent to reduce the viscosity, and removing the solvent in the next step (Patent Document 1: Japanese Patent Application Laid-Open No. 2005-239843), 2) High viscosity thermoplastic resin A method of removing a medium after impregnating a continuous fiber bundle with an emulsion and a dispersion of the powder (Patent Document 2: JP-A-2002-249984), 3) Continuously heating a high-viscosity thermoplastic resin powder in a fluidized bed Method of heat-melt impregnation after putting in fiber bundle (Patent Document 3: Japanese Patent No. 3672043), 4) Opening and squeezing continuous fiber bundle immersed in molten resin, and applying pressure to resin Examples thereof include a pultrusion method (Patent Document 4: Japanese Patent Laid-Open No. 2009-143158) and the like that are mechanically impregnated. Furthermore, 5) a method for improving the impregnation property by improving the wettability of the fiber with respect to the thermoplastic resin by modifying the surface of the fiber with a sizing agent, a coupling agent or the like has been proposed (Patent Document 5). : JP-A-61-236832).

Japanese Patent Laid-Open No. 2005-239843 JP 2002-249984 A Japanese Patent No. 3672043 JP 2009-143158 A Japanese Patent Application Laid-Open No. 61-236832

If there is an unimpregnated portion (void) of the matrix resin in the composite material (FRTP), the mechanical properties are deteriorated. For this reason, various techniques for preventing the generation of voids as much as possible have been proposed. A plurality of techniques for reducing the void ratio have been proposed in the patent document.

For example, Japanese translations of PCT publication No. 2006-523543 discloses a method of forming a prepreg having substantially no pores. The term “substantially poreless” as used in this publication means that pores that can be measured are not included (step 0053). Further, Patent Document 1 (Japanese Patent Laid-Open No. 2005-239443) discloses a prepreg having the lowest void ratio measured by a sulfuric acid decomposition method and using 0.2% thermoplastic resin (Example 3). ). However, since the resin impregnation property is a rate-determining factor for productivity, it is very difficult to achieve both a low void ratio and high productivity.

The present invention relates to a production method for producing a unidirectional fiber-reinforced tape-shaped composite material (FRTP) with a reduced void fraction with high productivity (high take-up speed) and by mixing reinforced fibers and resin uniformly and homogeneously. And a manufacturing apparatus and a method for manufacturing a random sheet using the tape-shaped composite material.

The present invention provides a distance between the support members when solidifying the thermoplastic resin while moving between the two support members while supporting the reinforcing continuous fiber bundle impregnated with the thermoplastic resin with two support members spaced apart from each other. A method for producing a unidirectional fiber-reinforced tape-shaped composite material, wherein L [mm] is a distance calculated by the following equation. L _ideal in the formula is an ideal value, and 200 mm is a condition defined by an empirical rule based on an experimental value.
0.9 x L _ideal [mm] <L [mm] <1.1 x L _ideal [mm] ... Formula (1)
L _ideal [mm] = [200 mm] × {(total number of filaments) / [(T + W) / (single yarn diameter)]] × (Vf / Vr)
[Total number of filaments]: Number of filaments of reinforcing fibers used [T]: Thickness [mm] of unidirectional prepreg to be produced
[W]: Width of unidirectional prepreg to be manufactured [mm]
[Single yarn diameter]: Diameter of reinforcing fiber filament used [mm]
[Vf]: Ratio of volume occupied by reinforcing fibers with respect to the total volume of the unidirectional prepreg to be produced [%]
[Vr]: Ratio of volume occupied by thermoplastic resin with respect to the total volume of the unidirectional prepreg to be produced [%]

The thermoplastic resin is impregnated into a reinforced continuous fiber bundle that has been opened by a solvent-soluble resin bath (wet method) or a molten resin bath (hot melt method). If necessary, the reinforced continuous fiber bundle immediately after the impregnation may be squeezed with a predetermined pressure.

The present invention provides a reinforced continuous fiber bundle that is preferably opened at a predetermined opening degree (1.1 to 1.30 times the target product width and 0.76 to 0.91 times the target product thickness). The thermoplastic resin is impregnated with a solvent-soluble resin bath or a molten resin bath, and squeezed with a predetermined pressure immediately after the bath. Thereafter, the thermoplastic resin is solidified while applying a predetermined tension to the reinforced continuous fiber bundle wetted with the resin.

In the production of a prepreg, it is important to increase the resin impregnation property by opening the reinforcing continuous fiber bundle uniformly and thinly. For this reason, a thick reinforced continuous fiber bundle or a reinforced continuous fiber bundle sheet having a large number of filaments is formed into a uniform and thin reinforced continuous fiber bundle sheet, which is prepregted in a solvent-soluble resin bath or a molten resin bath. The degree of opening (opening degree) is such that the reinforcing continuous fiber bundle to be used is 1.1 to 1.30 times as wide as the target product width, and 0.76 to 0.91 times as thick as the target product thickness.

At the time of resin solidification of the reinforced continuous fiber bundle wetted with the resin, an appropriate fulcrum distance and an appropriate tension are maintained corresponding to the width and thickness of the reinforced continuous fiber bundle, and the reinforced continuous fiber bundle is solidified while being conveyed. By this solidification, a unidirectional fiber-reinforced tape-shaped composite material having a low void ratio is obtained.
Hereinafter, the manufacturing method of the tape-shaped composite material of this invention is demonstrated.

(Reinforced continuous fiber bundle)
The reinforced continuous fiber bundle used in the present invention includes, for example, an aramid fiber, a polyethylene fiber, an organic fiber such as a polyparaphenylene benzoxador (PBO) fiber, a glass fiber, a carbon fiber, a silicon carbide fiber, an alumina fiber, a tyrano fiber, Examples thereof include inorganic fibers such as basalt fibers and ceramic fibers, metal fibers such as stainless fibers and steel fibers, and reinforced fibers using boron fibers, natural fibers, modified natural fibers, and the like as fibers. These reinforcing fibers are preferably composed of several thousand or more filaments. Moreover, the reinforcing fiber to be used is not limited to one kind, and two or more kinds can be used in combination.

(Pre-impregnation)
In the case of a solvent-dissolved resin bath, the same thermoplastic resin solution as the bath is applied to the reinforced continuous fiber bundle just before the bath with a nozzle from one side, and the resin voids contained in the reinforced continuous fiber bundle are continuously reinforced by the thermoplastic resin solution. Force exclusion to the opposite side of the fiber bundle. By passing through a solvent-soluble resin bath in this state, the reinforced continuous fiber bundle can be completely filled with the thermoplastic resin solution without voids.

(Solvent-soluble resin bath)
The resin used in the solvent-soluble resin bath (wet method) is preferably a thermoplastic resin having a viscosity of 10 mPa · s to 3500 mPa · s when heated and melted. An example of this thermoplastic resin is not particularly limited, but a thermoplastic resin that is excellent in impact resistance and easy to mold is preferable.

Examples of such thermoplastic resins include polyamide resins represented by nylon 6, nylon 12, nylon 66, and nylon 46, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyethylene, and polypropylene. Such as polyolefin resins, polyether ketone resins, polyphenylene sulfide resins, polyetherimide resins, polycarbonate resins, thermosetting resins, thermoplastic resins, copolymers thereof, modified products, And two or more types of blended resins.

Further, in order to further improve the impact resistance, an elastomer or a resin in which a rubber component is added to the above resin may be used. A thermoplastic resin that is solubilized in a solvent is also suitable. The solvent for dissolving the resin is not particularly limited. For example, NMP (N-methyl-2-pyrrolidone) can be used.

In addition, it is also possible to use a molten resin impregnation bath (hot melt method or dry method) instead of the solvent-soluble resin bath, and the same thermoplastic resin as described above can also be used in this molten resin impregnation bath.

The weight average molecular weight A of the thermoplastic resin is desirably a predetermined low molecular weight A (A = 1000 to 28000) in order to ensure good impregnation and low voiding after solidification. For example, molecular weight A = 0.1C to 0.7C (C: molecular weight of random sheet). And in order to ensure the strength after solidification, it is desirable to carry out polycondensation until the weight average molecular weight becomes at least the molecular weight B [B = 10000 to 30000] in the drying / solidification step or cooling / solidification step described later.

The reinforced continuous fiber bundle to be used in the solvent-dissolved resin bath is preferably expanded or opened, or is preferably impregnated with resin while being expanded or opened. The thickness of the reinforced continuous fiber bundle when the solvent-soluble resin bath is used is desirably 10 μm to 50 μm.

Even in the method of impregnating with resin while spreading or opening, the impregnation process can be simplified and shortened by setting the width and thickness of the reinforced continuous fiber bundle to be used. That is, in order to sufficiently impregnate the reinforced continuous fiber bundle 10 with no thermoplastic resin without voids, if the thickness of the reinforced continuous fiber bundle is 100 μm or more as in the prior art, the reinforced continuous fiber bundle is several m in the resin bath. It is necessary to pass at a take-up speed of less than 1 minute. If the resin bath is passed at a higher speed than that, the impregnation of the thermoplastic resin becomes poor. Therefore, the resin impregnation property of the tape-shaped composite material becomes the rate-limiting factor of the productivity.

In contrast, according to the present invention, the thickness of the reinforced continuous fiber bundle is less than half that of the conventional one as described above, and the resin impregnation property in the solvent-dissolving resin bath can be enhanced. There is a great advantage that it will not be. Therefore, a take-up speed of 1 to 15 m / min is possible while maintaining good impregnation properties, and both impregnation properties and productivity can be achieved.

(Aperture)
The reinforced continuous fiber bundle immediately after coming out of the liquid surface of the solvent-dissolving resin bath is drained by squeezing with a roller. The drawing pressure P applied to the roller is 0.05 MPa to 0.3 MPa (more preferably 0.1 MPa to 0.25 MPa). Thereby, void removal and resin amount control are performed. The amount of the resin is controlled so that the reinforcing fiber volume content Vf in the unidirectional fiber-reinforced tape-shaped composite material is Vf = 30 to 65%. If the volume content is higher than 65%, the number of entangled portions (unimpregnated portions) between the fibers increases, making it difficult to make a voidless. If the volume content is less than 30%, it is difficult to ensure the strength of the composite material. (Other ranges: 10% to 70%, 30% to 55%)

(Solidification process)
The solidification process can select the solidification method suitably according to the state of resin to be used. When the resin impregnated by the solvent impregnation method is solidified, a drying furnace with a blower as a heating unit is used in the solidification step. The drying furnace temperature is preferably not less than the evaporation temperature of the solvent, not more than 2/3 of the ignition temperature, and is preferably heated.

When using a high-melting resin dissolved in a high-boiling solvent, the drying furnace itself is kept in a heat-reserving tank and steam is sucked in order to suppress precipitation due to changes in the ambient temperature of the solvent evaporation and coagulation processes. This method is also preferable. Alternatively, a method in which a low boiling point solvent is mixed to increase the evaporation amount can be used.

Also, in the case of melting and impregnating into a reinforced continuous fiber bundle by heating and melting a pellet-like, film-like or powder-like resin as in the melt impregnation method (hot melt method or dry method) after heating, a cooler is used in the solidification process. Use.

The drying furnace or cooler used in the solidification process may be either vertical or horizontal, but it prevents unmixed resin from dripping during drying and solidification to prevent the mixed state of the reinforced continuous fiber bundle and resin from being disturbed. Is preferably a vertical type.

Rollers as support members are arranged before and after the drying furnace or cooler, and the reinforced continuous fiber bundle impregnated with resin runs freely between the front and rear rollers in the drying furnace / cooler.

(Roller fulcrum distance and tension)
In the present invention, the inter-roller fulcrum distance L [mm] in the solidification process is made significantly shorter than in the prior art. The fulcrum distance L can be calculated by the following equation (1). L _ideal is an ideal fulcrum distance, and a fulcrum distance in a range of ± 10% based on L _ideal is desirable. 200 mm in the equation is a condition defined by an empirical rule based on experimental values.
0.9 × L _ideal [mm] <L [mm] <1.1 × L _ideal [mm] (1)
L _ideal [mm] = [200 mm] × {(total number of filaments) / [(T + W) / (single yarn diameter)]} × (Vf / Vr)
[Total number of filaments]: Number of filaments of reinforcing fibers used [T]: Thickness [mm] of unidirectional prepreg to be produced
[W]: Width of unidirectional prepreg to be manufactured [mm]
[Single yarn diameter]: Diameter of reinforcing fiber filament used [mm]
[Vf]: Ratio of volume occupied by reinforcing fibers with respect to the total volume of the unidirectional prepreg to be produced [%]
[Vr]: Ratio of volume occupied by thermoplastic resin with respect to the total volume of the unidirectional prepreg to be produced [%]
Further, the tension of the reinforced continuous fiber bundle when the reinforced continuous fiber bundle is dried and solidified is 0.1 cN / dtex to 0.25 cN / dtex.

Conventionally, the fulcrum distance between rollers at the time of solidification is about twice that of L _ideal , and the tension is about 10 times that of the present invention. That is, in the present invention, the resin-impregnated reinforced continuous fiber bundle is solidified with a much shorter span and lower tension than before. By solidifying with a short span and low tension in this way, the directionality of the fiber may be disturbed or cracked due to shrinkage of the impregnated resin accompanying dry solidification of the solvent-impregnated fiber bundle or cooling and solidification of the melt-impregnated fiber bundle. Can be prevented.

Further, when the single yarn diameter, Vf and Vr are constant, the fulcrum distance L between the rollers becomes longer as the tape becomes thicker (the total number of filaments increases by that amount), and the fulcrum becomes smaller as the tape becomes thinner (the total number of filaments decreases by that amount). The distance L is shortened. Further, in the volume ratio of the resin and the fiber contained in the tape at this time, when the other parameters are constant and the fiber amount is large, the volume shrinkage due to the aggregation of the resin does not occur, and the fulcrum distance L becomes long, When the amount of resin is large, the fulcrum distance L is shortened.

In the solidification step, it is desirable that the resin impregnated in the reinforced continuous fiber bundle (low molecular weight A = 3500 to 25000) is polycondensed until the weight average molecular weight is at least molecular weight B [high molecular weight B = 10000 to 30000]. As a result, a tape-shaped composite material having less voids and less variation in thickness and excellent in uniformity and surface smoothness can be obtained. This tape-shaped composite material can be used for various applications in the form of a single layer or a laminated layer maintaining unidirectionality in the form of a tape.

Moreover, the obtained tape-shaped composite material can be cut into short strips, and the strips can be oriented and laminated so as to be pseudo-isotropic. The laminate is preferably heated to cause the thermoplastic resin to undergo a polymerization reaction until a desired molecular weight C [C = 35000 or more] is reached. This polymerization reaction can increase the strength of the laminate. The laminate can be shaped into a desired shape using a press in a heat-softened state. With this forming form, interlayer deaeration of the laminate can be performed simultaneously.

In the present invention, by impregnating the impregnating resin of the continuous fiber bundle with a short fulcrum distance in a predetermined range calculated by the above-described formula (1), the directionality of the fiber is disturbed due to shrinkage of the impregnating resin accompanying the solidification, Since cracking can be prevented, a unidirectional fiber-reinforced tape-shaped composite material having a low void ratio can be manufactured with high productivity and low cost. In addition, uniform and homogeneous mixing of reinforcing fibers and resin can be achieved, thereby preventing curling of the unidirectional fiber-reinforced tape-like composite material, and bulk-up of random sheets using the composite material. The generation of voids can be prevented and the quality and strength can be improved.

It is a schematic side view of the manufacturing apparatus of a unidirectional fiber reinforced tape-shaped composite material. It is an enlarged view of 1A part of FIG. It is an enlarged view of the 1B part of FIG. The drying process is shown, (a) is a schematic side view of the drying furnace, (b) is a plan view showing a contracted state of the tape-shaped composite material. It is a figure explaining the swivel rod of a tape-shaped composite material, and its measuring method. It is a table | surface of Examples 1-3 and Comparative Examples 1-4 of a tape-shaped composite material. A random sheet is schematically shown, (a) is a perspective view of the random sheet, (b) is a schematic view showing a state of press forming the random sheet of the present invention, (c) is a conventional random sheet It is the schematic which shows the state which shape-pressed. It is a table | surface which shows Example 1 and Comparative Examples 1-3 of a random sheet. It is a table | surface which shows the comparative examples 4 and 5 of a random sheet.

(Unidirectional fiber-reinforced tape-shaped composite)
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a manufacturing apparatus used for manufacturing a unidirectional fiber-reinforced tape-like composite material of the present invention. This manufacturing apparatus includes a winding package 21 of a reinforced continuous fiber bundle 10 expanded, a tension control dancer roll 22, a pair of drawer rollers 23, a resin applicator 24, a solvent dissolving resin bath 25, an impregnation roller 26, an intermediate roller. 27, a squeezing roller 26, a first support roller 29, a drying furnace 30, a second support roller 31, and a take-up roll 32.

The thermoplastic resin is applied to the reinforced continuous fiber bundle 10 in the air immediately before the resin bath by the nozzle 24a of the resin applicator 24. By applying resin from one side of the reinforced continuous fiber bundle 10 with the nozzle 24a, the resin voids of the reinforced continuous fiber bundle 10 are forcibly removed to the opposite side. The pressure of the resin discharged from the nozzle 24a is preferably a pressure at which resin voids can be forcibly removed, and a pressure that does not disturb the unidirectionality and fiber spacing of the reinforced continuous fiber bundle 10. The resin coating process using the nozzle 24a may be performed a plurality of times by arranging a plurality of resin applicators 24.

By applying the resin, the resin penetrates into the inside of the fiber bundle, and the resin can be included while expanding the space between the fibers, so that a sufficient amount of resin can be secured inside the fiber bundle. In this state, by passing the reinforced continuous fiber bundle 10 from the impregnation roller 26 to the squeezing roller 28 in the solvent-soluble resin bath 25, it is possible to uniformly impregnate the solvent-soluble resin and reduce voids.

Further, in the method of passing the resin bath while being supported by the rollers, it is preferable that the resin bath is passed through a plurality of rollers, rather than being transported while being supported by one roller. However, when a strong resistance is applied such that the resin impregnated in the reinforced continuous fiber bundle 10 is squeezed out while the reinforced continuous fiber bundle 10 passes through the roller, the resin contained between the fibers and the fibers becomes the fiber-fiber. It is squeezed because the distance between them is reduced.

If it does so, a unidirectional prepreg cannot be manufactured with high resin content. Accordingly, the tension applied to the reinforced continuous fiber bundle in the resin bath is preferably as low as possible because the resin penetrates between the fibers, and the appropriate tension is preferably 0.1 cN / dtex or less. In addition, you may provide the heating function according to the characteristic of resin to be used with respect to the solvent melt | dissolution resin bath 25. FIG.

In the squeezing process, shrinkage due to surface tension occurs on the liquid surface of the solvent-soluble resin bath 25. For this reason, while supporting the reinforced continuous fiber bundle 10 at the nip portion with the intermediate roller 27, the squeezing roller 28 suppresses with a pressing force of 0.05 MPa to 0.3 MPa, preferably 0.1 MPa to 0.25 MPa. It is preferable to transport the reinforced continuous fiber bundle 10 impregnated with resin.

Further, if an excessively strong pressure is applied between the intermediate roller 27 and the squeezing roller 28, the resin flows out from the reinforced continuous fiber bundle more than necessary. If it does so, a required quantity of resin cannot be ensured in the clearance gap according to the thickness of the unidirectional prepreg of a final product. Therefore, a necessary minimum gap is secured between the intermediate roller 27 and the squeezing roller 28, and an appropriate pressing force is applied while passing the reinforced continuous fiber bundle 10 through the gap.

After the reinforced continuous fiber bundle 10 passes through the squeezing roller 28, a drying / solidifying step is performed on the reinforced continuous fiber bundle 10 by a drying furnace 30 as shown in FIG. The relationship between the fulcrum distance L and the appropriate tension T in this drying / solidification step is the relationship of the above-described formula (1).

When the fulcrum distance L is increased by 10% or more than the ideal value (L _ideal ), a large tension must be applied to the reinforced continuous fiber bundle 10. Then, due to the increase in the tension of the reinforced continuous fiber bundle 10, the meandering or non-parallel fiber single yarn contained in the fiber bundle restrains other fiber bundles with the increased tension, shrinks in width, and forms a bundle. As a result, the resin is squeezed out. If it does so, it will not be in the state where reinforced fiber and resin were mixed uniformly and homogeneously.

In addition, the unidirectional prepreg having sufficient quality cannot be manufactured due to damage of the reinforcing fiber due to a large tension. Also, if the fulcrum distance L is made 10% or more smaller than the ideal value (L _ideal ), the resin will be insufficiently solidified, and this insufficiently solidified resin will be squeezed out of the fiber bundle in the conveying process, and the resin The homogenous distribution will be impaired. For this reason, the fulcrum distance mentioned above is needed. Here, “uniform / homogeneous” means not only a mixed state of fibers and resin that can be observed with a microscope but also a qualitatively uniform mixed state of fibers and resin that cannot be observed with a microscope.

(Relationship between uniformity and homogeneity of fiber and resin in fiber bundle and curl of fiber bundle)
If the reinforcing fiber and the resin are not mixed uniformly and homogeneously, the prepreg of the reinforcing fiber bundle curls and does not become completely flat when the prepreg is placed on a flat surface. Then, for example, when a prepreg is cut into a predetermined size and a random sheet is laminated and formed, the random sheet is bulked up and easily includes voids therein. Also, when cutting the prepreg, the fiber bundle floats from the cutting blade, and the cut surface tends to crack, cracks or fluff, which also causes bulk-up and voids, resulting in product quality reduction and strength reduction. Cause.

Therefore, in the embodiment of the present invention, the quality control of the reinforced fiber bundle prepreg product is performed by determining the uniformity and homogeneity of the fiber and the resin in the prepreg according to the curl size of the prepreg of the reinforcing fiber bundle. did. In other words, when the reinforcing fiber bundle is curled, swirling wrinkles occur in the tape-shaped composite material as shown in FIG. 3, so the curling angle is expressed by the swiveling angle, which is used for quality control of prepreg products. To do.

FIG. 3 is a diagram for explaining a swirl rod and its measuring method. As shown in FIG. 3, the reinforcing continuous fiber bundle 10 as a prepreg is cut at a predetermined length H, and its upper end portion is fixed by a clip 40 to naturally Hanging in the state. Here, the predetermined length H is 1 m when the width of the fiber bundle 10 is within 30 mm. In addition, when the width | variety of the fiber bundle 10 exceeds 30 mm, predetermined length H shall be over 1 m so that it may mention later.

In this state, the turning angle θ of the fiber bundle lower end portion 10a is measured. When fibers and resin are mixed uniformly and homogeneously, the turning angle θ of the fiber bundle lower end portion 10a is usually less than 360 degrees. If the fibers and the resin are not mixed uniformly and homogeneously, the turning angle θ of the fiber bundle lower end portion 10a becomes 360 degrees or more. This is an empirical rule obtained by the applicant of the present invention by repeating many experiments.

When the width of the fiber bundle 10 exceeds 30 mm, the turning angle θ is 360 degrees or more even if the fibers and the resin are mixed uniformly and homogeneously. Therefore, when the width of the reinforcing fiber bundle 10 exceeds 30 mm, the predetermined length H is set to more than 1 m.

The relationship between the width of the reinforcing fiber bundle 10 and the predetermined length H can be determined by conducting a plurality of experiments under the condition that the turning angle θ is less than 360 degrees when the fibers and the resin are mixed uniformly and homogeneously. . Thus, when the fibers and the resin are mixed uniformly and homogeneously, the turning angle θ is always less than 360 degrees regardless of the width of the fiber bundle. By doing so, it is possible to perform unified management in which the turning angle θ is less than 360 degrees, and quality management of a tape-shaped reinforcing fiber bundle having an arbitrary width is facilitated.

FIGS. 3A and 3B show an ideal case where the fibers and the resin of the fiber bundle 10 are mixed uniformly and homogeneously. In this case, the turning angle θ of the fiber bundle lower end portion 10a is 0 degree or less than 360 degrees as shown in (c).

If the reinforcing fibers of the reinforced continuous fiber bundle 10 and the resin are not uniformly and homogeneously mixed, the turning angle θ becomes 360 degrees or more as shown in (d), or the turning and warping are mixed as shown in (e). It will be in the state.

(Examples and comparative examples)
Next, Example 1-3 of the unidirectional prepreg manufactured by the manufacturing method mentioned above and the comparative example manufactured by changing conditions are demonstrated with FIG. FIG. 4 is a table showing the properties of the product prepregs of Examples 1 to 3 and Comparative Examples 1 to 4 in association with respective specifications.

The thickness and width of the unidirectional prepreg were measured 10 times per 1 m in the length direction with a micro gauge. The void ratio was measured according to JIS K 7075 (2011). As evaluation of impregnation property, a test piece laminated with a unidirectional prepreg was prepared, and a cross section was observed. As the reinforcing fiber, carbon fiber trading card T700SC-12k (total number of filaments: 12,000, single yarn diameter: 0.007 mm) manufactured by Toray Industries, Inc. was used. As the thermoplastic resin, water-soluble modified polyamide was used, and the viscosity was 2200 mPa · s (normal temperature). In addition, in the evaluation of the homogeneity of the resin and the fiber, it was determined whether or not the prototype prepreg was curled (swirl), and the impregnation state of the resin was confirmed.

[Example 1] A prototype was manufactured for the purpose of producing a unidirectional prepreg having a Vf of 50% and a Vr of 50% of a width of 30 mm and a thickness of 0.05 mm. As the resin, a water-soluble modified polyamide was used. Drying and solidification were performed under the manufacturing conditions of impregnation step incident tension of 0.08 cN / dtex, drying / solidification portion fulcrum distance of 550 mm, and formula (1) to 503.1 mm <ideal fulcrum distance of 560 mm <615.0 mm). The tension was 0.2 cN / dtex, a thermocouple was installed in the drying / solidification tank, the ambient temperature was 180 ° C., and the yarn speed (take-up speed) was 15 m / min. As a result, a sample having a Vf of 47% and a thickness of 0.053 mm was obtained. Further, the turning angle θ was 92 degrees and less than 360 degrees, and the turning tack was judged as “None” (fiber and resin were mixed uniformly and homogeneously).

[Comparative Example 1] A prototype was manufactured for the purpose of producing a unidirectional prepreg having a Vf of 50% and a Vr of 50% of a width of 30 mm and a thickness of 0.05 mm. The production conditions are as follows: impregnation step incident tension is 0.08 cN / dtex, drying / solidification part fulcrum distance is 800 mm, formula (1) is outside the upper limit range of fulcrum distance, drying / solidification part tension is 0.2 cN / dtex, and drying is performed. -The atmosphere temperature in the solidification tank was 180 ° C, and the yarn speed was 15 m / min. As a result, the yarn width was reduced, the thickness was increased, and a target sample could not be obtained. For this reason, the measurement of the swivel rod was omitted.

[Comparative Example 2] A prototype was manufactured for the purpose of producing a unidirectional prepreg having a Vf of 50% and a Vr of 50% of a width of 30 mm and a thickness of 0.05 mm. The production conditions were impregnation step incident tension of 0.08 cN / dtex, drying / solidification part fulcrum distance of 430 mm which is 10% or more shorter than ideal fulcrum distance of 560 mm, drying / solidification part tension of 0.2 cN / dtex, The atmosphere temperature in the solidification tank was 180 ° C., and the yarn speed was 15 m / min. As a result, the drying was insufficient, the film adhered to the transport roller immediately after drying, resulting in a defective process, and a target sample could not be obtained.

Therefore, the atmospheric temperature in the drying / solidification tank was further increased from 180 ° C. to 220 ° C., but the surface of the unidirectional prepreg surface was deteriorated due to combustion of the resin and vaporization of the solvent, resulting in bubbles and poor surface properties. Cracks along the fiber direction occurred, and the target sample was not obtained. For this reason, the measurement of the swivel rod was omitted. In addition, while the atmosphere temperature in the drying / solidification tank was kept at 180 ° C. and the drying / solidification part fulcrum distance was increased from 430 mm to 500 mm, further implementation was performed, but a significant improvement effect of process failure was recognized due to insufficient drying. There wasn't.

[Comparative Example 3] A prototype was manufactured for the purpose of producing a unidirectional prepreg having a Vf of 50% and a Vr of 50% of a width of 30 mm and a thickness of 0.05 mm. The production conditions are as follows: impregnation step incident tension is 0.08 cN / dtex, drying / solidification part fulcrum distance is 1000 mm, formula (1) is outside the upper limit range of fulcrum distance, drying / solidification part tension is 0.5 cN / dtex, and drying is performed. -The atmosphere temperature in the solidification tank was 180 ° C, and the yarn speed was 15 m / min. As a result, the width could be made wider than that of Comparative Example 2, but irregularities were generated on the surface. In the cross-sectional state, the resin was biased. The obtained sample tape had a swivel rod (turning angle θ = 822 degrees> 360 degrees), and it was confirmed that the resin was excessive on one side of the prepreg surface, and the resin impregnation was uneven.

[Comparative Example 4] A prototype was manufactured for the purpose of manufacturing a unidirectional prepreg having a Vf of 50% and a Vr of 50% of a width of 30 mm and a thickness of 0.05 mm. The production conditions are as follows: impregnation step incident tension is 0.08 cN / dtex, drying / solidification portion fulcrum distance is 550 mm, formula (1) is within the upper limit range of fulcrum distance, and drying / solidification portion tension is 0.07 cN / dtex. -The atmosphere temperature in the solidification tank was 180 ° C, and the yarn speed was 15 m / min. As a result, the reinforcing fiber was damaged, a process failure occurred, a crack occurred on the prepreg surface, and a target sample could not be obtained. For this reason, the measurement of the swivel rod was omitted.

[Example 2] A prototype was manufactured for the purpose of producing a unidirectional prepreg having a width of 20 mm and a thickness of 0.07 mm with Vf of 40% and Vr of 60%. The production conditions are as follows: impregnation step incident tension is 0.08 cN / dtex, drying / solidification part fulcrum distance is 550 mm, formula (1) is within the range of 503.1 mm <ideal fulcrum distance 559 mm <615.0, and drying / solidification part The tension was 0.2 cN / dtex, the atmospheric temperature in the drying / solidification tank was 180 ° C., and the yarn speed was 15 m / min. As a result, a prepreg having a Vf of 41% and a thickness of 0.058 mm had no swirling wrinkles (turning angle θ = 111 degrees <360 degrees), and a sample with a good resin impregnation state was obtained.

[Example 3] A prototype was manufactured for the purpose of producing a unidirectional prepreg having a width of 20 mm and a thickness of 0.05 mm with Vf of 60% and Vr of 40%. The production conditions are: impregnation process incident tension of 0.08 cN / dtex, drying / solidification part fulcrum distance of 1200 mm, formula (1) from the upper limit range of 1131 mm <ideal fulcrum distance 1257 mm <1383 mm, and drying / solidification part tension of 0 .2 cN / dtex, the atmospheric temperature in the drying / solidification tank was 180 ° C., and the yarn speed was 15 m / min. As a result, a prepreg having a Vf of 59% and a thickness of 0.051 mm had no swirling wrinkles (turning angle θ = 106 degrees <360 degrees), and a sample with a good resin impregnation state was obtained.

From the results of Example 1-3 and Comparative Example 1-4, Example 1-3 had a good resin-impregnated state (◎, ○), no swirling flaws, and a void ratio of 0.6% or less. . On the other hand, in Comparative Example 1-4, the resin impregnation state was poor (Δ) or extremely poor (x), and the void ratio was 0.6% or more. In Comparative Example 4 having a void ratio of 0.6%, the surface quality (smoothness) was extremely poor and thread breakage occurred.

(Random sheet)
Next, a method for producing a random sheet using the tape-shaped composite material obtained by the above-described method will be described with reference to FIGS. 5, 6A, and 6B. The tape-shaped composite material of the reinforced continuous fiber bundle 10 obtained by the above method is cut into a length of several millimeters to several tens of millimeters. As shown in FIG. 5A, the cut tape pieces are randomly oriented and laminated to a desired thickness to obtain a laminate 110. The laminated body 110 is preheated to soften the resin, and the softened laminated body 110 is set in a press machine and shaped as shown in FIG. 5B.

Conventionally, the thickness of the tape pieces to be laminated was thick as shown in FIG. For this reason, when it was set as the laminated body 210 which laminated | stacked the tape piece to desired thickness, it was hard to bend and shapeability was not good. Since the tape-like composite material obtained in the embodiment of the present invention has a low void ratio and good surface smoothness, the tape-like composite material can be made very thin without breaking the yarn. For this reason, after a tape piece lamination | stacking, the bending process of a laminated body sheet is easy and its shapeability is favorable. Moreover, since curling of the tape-shaped composite material does not occur, there is no bulk up of the random sheet, and void inclusion due to the bulk up can be prevented, so that the shaped product has high strength and good surface smoothness.

The results of this random sheet comparison test are shown in FIGS. 6A and 6B. As can be seen from the results, the random sheet of the present invention has high strength and good moldability.

The CV values in FIGS. 6A and 6B show pseudo-isotropic properties, and are the ratio (standard deviation / average value) between the tensile strength and the tensile elastic modulus in 15 ° increments in one composite material that is not laminated. . The smaller the CV value, the more pseudo-isotropic, ideally 1. Carbon fiber trading card T700SC-12k manufactured by Toray Industries, Inc. was used as the reinforcing fiber used for the tape. As the thermoplastic resin, water-soluble modified polyamide was used, and the viscosity was 2200 mPa · s (normal temperature).

[Example 1] The reinforced continuous fiber bundle is a carbon fiber bundle, and the thermoplastic resin is a modified polyamide. The yarn was manufactured at a yarn speed of 15 m / min, and the void ratio was 0.6%. Using this unidirectional prepreg, strip-shaped pieces were produced. The size of the strip-shaped piece is 10 mm in width, 20 mm in length, and 0.05 mm in thickness. The average molecular weight of the strips is 11000. The random sheet has a width of 200 mm, a length of 200 mm, and a thickness of 2 mm. The random sheet has a molecular weight of 36000. The volume ratio Vf of the reinforcing fibers is 45%. There was no outflow of fibers due to the resin flow during sheet processing, no disturbance in fiber linearity, high strength, a low CV value, and a random sheet with good surface appearance and quality.

[Comparative Example 1] As a comparison with Example 1, the average molecular weight of the strip-shaped pieces was set to 2000, and polymerization was advanced to a predetermined molecular weight at the time of manufacturing the random sheet. The random sheet has a molecular weight of 37000. The volume ratio Vf of the reinforcing fibers is 45%. Others are the same as in the first embodiment. Residual voids were reduced due to fiber outflow due to resin flow during sheet processing, fiber linearity disorder, and resin flow, but the strength was low.

[Comparative Example 2] The average molecular weight of the strip-shaped piece is 20000. The random sheet has a molecular weight of 37000. The volume ratio Vf of the reinforcing fibers is 45%. Others are the same as in the first embodiment. The sheet could be formed without any outflow of fibers due to the resin flow during sheet processing and disturbance of fiber linearity. Further, the physical properties of the sheet were high strength, low CV value, and a random sheet with good surface appearance and quality was obtained.

[Comparative Example 3] The average molecular weight of the strip-shaped piece is 25,000. The random sheet has a molecular weight of 36000. The volume ratio Vf of the reinforcing fibers is 45%. Others are the same as in the first embodiment. The sheet could be formed without any outflow of fibers due to resin flow during processing of the sheet and disturbance of fiber linearity, but voids remained inside, the physical properties of the sheet were low in strength, high in CV value, surface appearance and quality. It was a bad result.

[Comparative Example 4] The average molecular weight of the strip-shaped piece is 11,000. The random sheet has a molecular weight of 36000. The volume ratio Vf of the reinforcing fibers is 80%. Others are the same as in the first embodiment. When the sheet was processed, there was not enough resin flow, many voids remained, the physical properties of the sheet were low in strength, the CV value was high, and in the surface appearance, the fibers were exposed, resulting in poor quality.

[Comparative Example 5] The average molecular weight of the strip-shaped piece is 11,000. The random sheet has a molecular weight of 36000. The volume ratio Vf of the reinforcing fibers is 60%. Others are the same as in the first embodiment. The sheet was formed without any outflow of fibers due to resin flow during processing of the sheet and disturbance of the linearity of the fibers, many voids remained, the CV value was high, and the surface appearance was good, but the quality was poor.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the claims.

10: Expanded reinforced continuous fiber bundle 21: Winding package of reinforced continuous fiber bundle 22: Dancer roll for tension control 23: A pair of drawing rollers 24: Resin applicator 25: Solvent-dissolving resin bath 26: Impregnation roller 27: Intermediate roller 28: squeezing roller 29: first support roller (first support member)
30: Drying furnace 31: Second support roller (second support member)
32: Winding roll

Claims (16)

When solidifying the thermoplastic resin while moving between the two supporting members while supporting the reinforcing continuous fiber bundle impregnated with the thermoplastic resin with two supporting members spaced apart from each other, a distance L [mm] between the supporting members Is a distance calculated by the following equation: A method for producing a unidirectional fiber-reinforced tape-like composite material.
0.9 × L _ideal [mm] <L [mm] <1.1 × L _ideal [mm]
L _ideal [mm] = [200 mm] × {(total number of filaments) / [(T + W) / (single yarn diameter)]} × (Vf / Vr)
[200 mm]: Specified distance obtained from experiments [total number of filaments]: number of filaments of reinforcing fiber to be used [T]: thickness of unidirectional prepreg to be manufactured [mm]
[W]: Width of unidirectional prepreg to be manufactured [mm]
[Single yarn diameter]: Diameter of reinforcing fiber filament used [mm]
[Vf]: Ratio of volume occupied by reinforcing fibers with respect to the total volume of the unidirectional prepreg to be produced [%]
[Vr]: Ratio of volume occupied by thermoplastic resin with respect to the total volume of the unidirectional prepreg to be produced [%] The method for producing a unidirectional fiber-reinforced tape-shaped composite material according to claim 1, wherein the thermoplastic resin is impregnated by a wet method and then dried and solidified while moving between the support members. The method for producing a unidirectional fiber-reinforced tape-like composite material according to claim 1, wherein the thermoplastic resin is impregnated by a hot melt method and then cooled and solidified while moving between the support members. The reinforced continuous fiber bundle is passed through a resin bath by a wet method, and the reinforced continuous fiber bundle immediately after coming out of the resin bath is pressed with a force of 0.05 MPa to 0.3 MPa to drain the liquid. Item 3. A method for producing a unidirectional fiber-reinforced tape-shaped composite material according to Item 2. The method for producing a unidirectional fiber-reinforced tape-shaped composite material according to claim 2 or 4, wherein a thermoplastic resin is applied to the reinforced continuous fiber bundle and then passed through a resin bath by a wet method. The unidirectional fiber reinforced tape according to any one of claims 1 to 5, wherein a degree of opening of the reinforced continuous fiber bundle at the time of solidifying the thermoplastic resin is set to 1.1 to 1.3. Method of manufacturing a composite material. The unidirectional fiber-reinforced tape-shaped composite material according to any one of claims 1 to 5, wherein the thickness of the reinforcing continuous fiber bundle at the time of solidifying the thermoplastic resin is 10 µm to 50 µm. Method. The reinforced continuous fiber bundle is impregnated with a thermoplastic resin having a weight average molecular weight A of 1000 to 28000, and then, when the thermoplastic resin is solidified, polycondensation is performed until at least the weight average molecular weight B is 10,000 to 30,000. The method for producing a unidirectional fiber-reinforced tape-shaped composite material according to any one of claims 1 to 7. The unidirectional fiber-reinforced tape-shaped composite material according to any one of claims 2 to 8, wherein the reinforcing fiber volume content in the unidirectional fiber-reinforced tape-shaped composite material is 30 to 65%. Manufacturing method. A resin bath part disposed in a conveying path of the reinforcing continuous fiber bundle and impregnating the reinforcing continuous fiber bundle with a thermoplastic resin;
Two support members that are arranged apart from each other on the downstream side in the transport direction of the resin bath part and support the reinforced continuous fiber bundle by applying a predetermined tension;
A solidifying part for solidifying the thermoplastic resin of the reinforcing continuous fiber bundle moving between the support members;
The apparatus for producing a unidirectional fiber-reinforced tape-shaped composite material, wherein the distance L [mm] between the support members is a distance calculated by the following equation.
0.9 × L _ideal [mm] <L [mm] <1.1 × L _ideal [mm]
L _ideal [mm] = [200 mm] × {(total number of filaments) / [(T + W) / (single yarn diameter)]} × (Vf / Vr)
[Total number of filaments]: Number of filaments of reinforcing fibers used [T]: Thickness [mm] of unidirectional prepreg to be produced
[W]: Width of unidirectional prepreg to be manufactured [mm]
[Single yarn diameter]: Diameter of reinforcing fiber filament used [mm]
[Vf]: Ratio of volume occupied by reinforcing fibers with respect to the total volume of the unidirectional prepreg to be produced [%]
[Vr]: Ratio of volume occupied by thermoplastic resin with respect to the total volume of the unidirectional prepreg to be produced [%] 11. The one-way structure according to claim 10, wherein the resin bath part includes a solvent-dissolved resin bath obtained by dissolving a thermoplastic resin with a solvent, and the solidified part includes a heating part that heats the reinforced continuous fiber bundle. Equipment for fiber-reinforced tape-like composites. The unidirectional fiber according to claim 10, wherein the resin bath part has a molten resin bath in which a thermoplastic resin is melted, and the solidified part has a cooling part for cooling the reinforced continuous fiber bundle. Equipment for manufacturing reinforced tape-like composite materials. The unidirectional fiber-reinforced tape-shaped composite material manufactured by the manufacturing method according to any one of claims 1 to 9, or the unidirectional fiber-reinforced tape-shaped composite material manufactured by the manufacturing apparatus according to any one of claims 10 to 12. A method for producing a reinforced fiber random sheet, characterized in that a large number of strip-like pieces obtained by cutting a material into strips are oriented and laminated so as to be pseudo-isotropic. 14. The plurality of strip-shaped pieces are oriented and laminated so as to be quasi-isotropic, and then the laminated body is subjected to a polymerization reaction until the weight average molecular weight C reaches a desired molecular weight of 3500 or more. Manufacturing method of reinforcing fiber random sheet. The molecular weight A of the thermoplastic resin impregnated by the production method according to any one of claims 1 to 9 or the production apparatus according to any one of claims 10 to 12 is 10 to 70% of the molecular weight C. The method for producing a reinforcing fiber random sheet according to claim 14. The method for producing a reinforced fiber random sheet according to any one of claims 13 to 15, wherein interlayer deaeration is performed by simultaneously proceeding a polymerization reaction and a pressure treatment after the strip pieces are laminated.

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