Drawing forming apparatus and method for producing fiber-reinforced polyamide

Abstract

To provide a pultrusion molding apparatus capable of efficiently removing lactam monomers and a method for producing fiber-reinforced polyamide.SOLUTION: A fiber material F is impregnated with ε-caprolactam (lactam monomer), and the ε-caprolactam impregnated in the fiber material F is polymerized to obtain fiber-reinforced polyamide P. The resulting fiber-reinforced polyamide P is heated in an open system, which makes it easier to vaporize unreacted ε-caprolactam from the fiber-reinforced polyamide P. This allows for more efficient removal of the ε-caprolactam from the fiber-reinforced polyamide P than when the ε-caprolactam is removed by hot water extraction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a drawing forming apparatus and a method for manufacturing fiber-reinforced polyamide, and more particularly, to a drawing forming apparatus and a method for manufacturing fiber-reinforced polyamide capable of efficiently removing lactam monomers.

Background Art

[0002] A technique for manufacturing fiber-reinforced plastic (FRP) by polymerizing a monomer impregnated in a fiber material is known. For example, Patent Document 1 describes a technique for manufacturing fiber-reinforced polyamide by heating and polymerizing ε-caprolactam impregnated in glass fiber. Since ε-caprolactam (monomer) has a lower viscosity when melted than the resulting polyamide (polymer), ε-caprolactam can be effectively impregnated between the fibers of glass fiber.

[0003] In this type of technique, there is a problem that unreacted (not fully polymerized) ε-caprolactam remains in the fiber-reinforced polyamide after polymerization. To address this problem, a technique of performing hot water extraction at a temperature at which ε-caprolactam melts (for example, 80 °C) is known, taking advantage of the property of ε-caprolactam that it has high solubility in water. This hot water extraction removes (extracts) unreacted ε-caprolactam from the fiber-reinforced polyamide, for example, by immersing the fiber-reinforced polyamide in hot water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-described conventional hot water extraction, a long time (for example, about 72 hours for a fiber-reinforced polyamide with a thickness of 0.6 mm) is required to remove a sufficient amount of ε-caprolactam. That is, there is a problem that lactam monomers such as ε-caprolactam cannot be efficiently removed from the fiber-reinforced polyamide.

[0006] The present invention has been made to solve the above-described problems, and an object thereof is to provide a drawing apparatus and a method for producing a fiber-reinforced polyamide capable of efficiently removing lactam monomers.

Means for Solving the Problems

[0007] To achieve this object, the drawing apparatus of the present invention manufactures a fiber-reinforced polyamide by drawing, and includes an impregnation part for impregnating a fiber material with a lactam monomer, a polymerization part for polymerizing the lactam monomer impregnated in the fiber material in the impregnation part to obtain a fiber-reinforced polyamide, and heating the fiber-reinforced polyamide obtained in the polymerization part. In an open system heating while vaporizing the unreacted lactam monomer a heating part, and the heating part A heating furnace is provided in which a space for heating the fiber-reinforced polyamide is formed inside in an atmosphere with a low oxygen concentration lower than that of air. The heating furnace includes a supply port for supplying a gas with a low oxygen concentration into the heating furnace, and an exhaust port for exhausting the gas with a low oxygen concentration supplied into the heating furnace from the supply port to the outside of the heating furnace. In the heating furnace, the fiber-reinforced polyamide is heated at a temperature at which the polyamide of the fiber-reinforced polyamide melts and is 290 °C or lower, and the unreacted lactam monomer vaporized from the fiber-reinforced polyamide is exhausted from the exhaust port is.

[0008] The method for producing a fiber-reinforced polyamide of the present invention includes an impregnation step of impregnating a fiber material with a lactam monomer, a polymerization step of polymerizing the lactam monomer impregnated in the fiber material in the impregnation step to obtain a fiber-reinforced polyamide, and heating the fiber-reinforced polyamide obtained in the polymerization step. In an open system heating while vaporizing the unreacted lactam monomer a heating step, and in the heating step A heating furnace in which a space for heating the fiber-reinforced polyamide is formed inside in an atmosphere with a low oxygen concentration lower than that of air is used. The heating furnace includes a supply port for supplying a gas with a low oxygen concentration into the heating furnace, and an exhaust port for exhausting the gas with a low oxygen concentration supplied into the heating furnace from the supply port to the outside of the heating furnace. In the heating furnace, the fiber-reinforced polyamide is heated at a temperature at which the polyamide of the fiber-reinforced polyamide melts and is 290 °C or lower, and the unreacted lactam monomer vaporized from the fiber-reinforced polyamide is exhausted from the exhaust port is.

Advantages of the Invention

[0009] The drawing apparatus according to claim 1 and claim 7According to the method for producing the fiber-reinforced polyamide described, since the fiber-reinforced polyamide is heated in an open system, unreacted lactam monomers can be easily vaporized from the fiber-reinforced polyamide. As a result, there is an effect that the lactam monomers can be efficiently removed from the fiber-reinforced polyamide.

[0010] Also Claim 1 The drawing forming apparatus described and the method for producing a fiber-reinforced polyamide according to claim 7 According to , next has the effects. Since the heating unit heats at a temperature at which the polyamide of the fiber-reinforced polyamide melts, the lactam monomers can be removed more efficiently than, for example, when heating to such an extent that the polyamide softens. This is presumably because the molecular motion of the polyamide molecules becomes active due to the melting of the polyamide, and the diffusion rate of the unreacted lactam monomers increases. On the other hand, since the heating unit heats the fiber-reinforced polyamide at a temperature of 290°C or lower, there is an effect that deformation due to a decrease in the viscosity of the fiber-reinforced polyamide and deterioration due to oxidation can be suppressed.

[0011] Also Claim 1 The drawing forming apparatus described and the method for producing a fiber-reinforced polyamide according to claim 7 According to , next has the effects. Since the heating unit heats the fiber-reinforced polyamide in an atmosphere with a low oxygen concentration where the oxygen concentration is lower than that of air, oxidation of the fiber-reinforced polyamide due to heating can be suppressed. That is, there is an effect that deterioration due to oxidation of the fiber-reinforced polyamide can be suppressed even when heating is performed at a high temperature at which the polyamide melts.

[0012] Also Claim 1 The drawing forming apparatus described and the method for producing a fiber-reinforced polyamide according to claim 7 According to , nextIt has the following effects. The heating unit includes a heating furnace in which a space for heating the fiber-reinforced polyamide is formed inside. Since the heating furnace is provided with a supply port for supplying a gas with a low oxygen concentration inside, an atmosphere with a low oxygen concentration can be formed inside the heating furnace. Since the gas with a low oxygen concentration supplied into the heating furnace from the supply port is exhausted from the exhaust port, the unreacted lactam monomer vaporized from the fiber-reinforced polyamide can be exhausted from the exhaust port together with the gas with a low oxygen concentration. As a result, it is possible to suppress an increase in the concentration of the lactam monomer in the heating furnace, so that there is an effect that the lactam monomer can be efficiently removed from the fiber-reinforced polyamide.

[0013] Claim 2 According to the drawing forming device described in claim 1 In addition to the effects exhibited by the drawing forming device described in claim

[0014] Claim 3 According to the drawing forming device described in claim 1 or 2 In addition to the effects exhibited by the drawing forming device described in claim

[0015] Claim 4 According to the drawing forming device described in claim, from claim 1 to 3In addition to the effects exhibited by the drawing forming apparatus according to any one of the above, the following effects are achieved. Since the polymerization section polymerizes the lactam monomer to obtain a fiber-reinforced polyamide with a thickness of 0.5 mm or less, the fiber-reinforced polyamide is more easily heated to the inside. As a result, unreacted lactam monomer is more easily removed from the fiber-reinforced polyamide. On the other hand, since the polymerization section polymerizes the lactam monomer to obtain a fiber-reinforced polyamide with a thickness of 0.1 mm or more, it is possible to suppress cracks and deformation from occurring during the forming of the fiber-reinforced polyamide. Therefore, there is an effect that the fiber-reinforced polyamide can be easily formed into a desired shape.

[0016] Claim 5 According to the drawing forming apparatus described in claim 4 In addition to the effects exhibited by the drawing forming apparatus according to claim

[0017] Claim 6 According to the drawing forming apparatus described in claim 5 In addition to the effects exhibited by the drawing forming apparatus according to claim

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, with reference to FIG. 1, the overall configuration of the drawing forming apparatus 1 will be described. FIG. 1 is a schematic diagram showing an outline of the drawing forming apparatus 1 according to an embodiment of the present invention.

[0020] As shown in FIG. 1, the drawing forming apparatus 1 is a drawing apparatus (fiber-reinforced polyamide manufacturing apparatus) that impregnates a fiber material F (carbon fiber in this embodiment) with a molding material C containing ε-caprolactam in an impregnation section 10 and polymerizes the molding material C impregnated in the fiber material F in a polymerization section 20. The fiber-reinforced polyamide P obtained by polymerization in the polymerization section 20 is cooled in a cooling section 40 after passing through heating in a heating section 30 (removal section for removing lactam monomer). A series of steps up to the cooling in this cooling section 40 are continuously performed while the fiber-reinforced polyamide do P is drawn in a drawing section 50. The fiber-reinforced polyamide P drawn in the drawing section 50 is cut by a slitter or a rotary cutter 60 (not shown) to produce a strip-shaped prepreg Pr.

[0021] The fiber material F wound around the spool S is drawn into the impregnation section 10 by drawing in the drawing section 50. The impregnation section 10 includes mixing tanks 11 and 12 for mixing materials for impregnating the fiber material F, a mixing section 13 for further mixing the mixed liquid supplied from those mixing tanks 11 and 12 to form a molding material C, and an impregnation tank 14 to which the molding material C mixed in the mixing section 13 is supplied.

[0022] The mixing tank 11 is a tank for mixing heat-melted ε-caprolactam and an activator (in this embodiment, hexamethylene diisocyanate), and the mixing tank 12 is a tank for mixing heat-melted ε-caprolactam and a polymerization catalyst (in this embodiment, ε-caprolactam sodium salt).

[0023] The mixed liquid mixed in these mixing tanks 11 and 12 is further mixed in the mixing section 13 to become the molding material C, and this molding material C is fed to the impregnation tank 14 by a pump (not shown). When the fiber material F is drawn into the molding material C stored in the impregnation tank 14, the molding material C containing ε-caprolactam is impregnated into the fiber material F (impregnation step).

[0024] The fiber material F impregnated with the molding material C (ε-caprolactam) is drawn into the polymerization section 20. The polymerization section 20 is provided with a mold for polymerizing the molding material C impregnated into the fiber material F. Since a known configuration can be adopted for this polymerization mold, a detailed description thereof is omitted. Examples of known configurations include the molds described in JP-A-07-096553, JP-A-2008-005572, and JP-A-2010-253733.

[0025] The mold in the polymerization section 20 is provided with heating means (for example, a heater), and by heating at a predetermined temperature (for example, 130 to 200°C) by this heating means, the molding material C impregnated into the fiber material F starts to polymerize (polymerization step).

[0026] Note that the impregnation section 10 and the polymerization section 20 are covered with a housing (not shown), and this housing is provided with a supply port and a discharge port for supplying and discharging an inert gas (for example, dry nitrogen gas). Therefore, the impregnation of the molding material C in the impregnation section 10 and the polymerization of the molding material C in the polymerization section 20 are performed in an inert gas atmosphere (or in a vacuum).

[0027] By polymerizing the molding material C (ε-caprolactam) impregnated in the fiber material F in the polymerization section 20, a polyamide (nylon 6) reinforced with the fiber material F, that is, a fiber-reinforced polyamide P is obtained. Unreacted ε-caprolactam that could not be completely polymerized in the polymerization section 20 remains in the fiber-reinforced polyamide P. In this embodiment, this unreacted ε-caprolactam is removed in the heating section 30 and recovered in the recovery section 70. The detailed configurations of these heating section 30 and recovery section 70 will be described with reference to FIG. 2. FIG. 2 is a perspective view schematically showing the heating section 30 and the recovery section 70.

[0028] As shown in FIG. 2, the heating section 30 for heating the fiber-reinforced polyamide P includes a rectangular parallelepiped heating furnace 31. Openings 32 extending in the width direction of the sheet-shaped fiber-reinforced polyamide P are formed on each end face of the upstream side (left side in FIG. 2) and the downstream side (right side in FIG. 2) of the heating furnace 31.

[0029] The opening 32 is formed in a shape corresponding to the cross-sectional shape of the fiber-reinforced polyamide P. That is, the opening 32 fiber has an opening area slightly larger than the cross-sectional area of the fiber-reinforced polyamide P (for example, the gap with the fiber-reinforced polyamide P is 10 mm or less), and the fiber-reinforced polyamide P continuously passes through the inside of the heating furnace 31 through this opening 32. In this embodiment, the case where the fiber-reinforced polyamide P is sheet-shaped is illustrated. However, for example, when drawing and molding a plurality of strip-shaped or rod-shaped fiber-reinforced polyamides P, a plurality of openings 32 corresponding to the cross-sectional shapes of those strip-shaped or rod-shaped may be formed in the heating furnace 31.

[0030] Supply ports 33 and exhaust ports 34 connecting the inside of the heating furnace 31 to the outside are formed on the upstream side and the downstream side end faces of the heating furnace 31. The supply port 33 is connected via a supply pipe 35 to a superheated steam generator (not shown), and the exhaust port 34 is connected via an exhaust pipe 36 to the recovery section 70 described later. Therefore, the superheated steam supplied from the supply port 33 is exhausted from the exhaust port 34 while heating the inside of the heating furnace 31. Due to this superheated steam, the temperature inside the heating furnace 31 is heated to a temperature at which the fiber-reinforced polyamide P (polyamide) melts.

[0031] The temperature at which the fiber-reinforced polyamide P (polyamide) melts (melting point) is about 225°C, and this temperature is higher than the melting point of ε-caprolactam (about 70°C). In the heating furnace 31, the fiber-reinforced polyamide P is not heated while in contact with a heavy alloy mold like the polymerization section 20 (in a closed system), but the fiber-reinforced polyamide P is heated in a form that passes through the internal space of the heating furnace 31 (in an open system non-contact with other members) (heating process). In this way, after polymerization (heating) in the polymerization section 20, by heating again in the heating furnace 31, unreacted ε-caprolactam can be easily vaporized (evaporated) from the fiber-reinforced polyamide P. Therefore, for example, compared with conventional hot water extraction, ε-caprolactam can be efficiently removed from the fiber-reinforced polyamide P in a short time.

[0032] Note that the temperature in the heating furnace 31 may be set so that the temperature of the fiber-reinforced polyamide P is at least higher than the melting point of ε-caprolactam, but this temperature is preferably set to the temperature at which the fiber-reinforced polyamide P softens (for example, 200°C or higher), and more preferably set to the temperature at which the fiber-reinforced polyamide P melts (for example, 260°C or higher). This is because as the temperature of the fiber-reinforced polyamide P rises (softens or melts), the molecular motion of the polyamide molecules becomes more active, and it can be expected that the diffusion rate of unreacted ε-caprolactam will increase (become more easily vaporized). Furthermore, it is most preferable to set the temperature of the fiber-reinforced polyamide P to exceed the boiling point of ε-caprolactam (lactam monomer) (for example, 270°C or higher in the case of ε-caprolactam). Thereby, unreacted ε-caprolactam becomes more easily vaporized from the fiber-reinforced polyamide P.

[0033] On the other hand, when the temperature of the fiber-reinforced polyamide P rises and exceeds, for example, 290°C, the viscosity of the polyamide decreases, making it easier to deform. Also, when heating is performed with superheated steam as in this embodiment, there is no problem because the fiber-reinforced polyamide P is less likely to oxidize. However, when heating is performed, for example, in air (an atmosphere containing oxygen), when the temperature exceeds 290°C, the fiber-reinforced polyamide P is likely to deteriorate due to oxidation. Therefore, in the heating furnace 31, it is preferable to heat the fiber-reinforced polyamide P at a temperature of 290°C or lower. This can suppress deformation due to a decrease in the viscosity of the fiber-reinforced polyamide P and deterioration due to oxidation.

[0034] That is, in the heating furnace 31, it is preferable to perform heating at a temperature that is equal to or higher than the melting temperature of the fiber-reinforced polyamide P and lower than 290°C. This can efficiently remove unreacted ε-caprolactam from the fiber-reinforced polyamide P while suppressing deformation due to a decrease in the viscosity of the fiber-reinforced polyamide P and deterioration due to oxidation.

[0035] Thus, since the fiber-reinforced polyamide P undergoes oxidative deterioration during heating in an atmosphere containing oxygen, in this embodiment, heating under a stream of superheated steam is employed. This allows the fiber-reinforced polyamide P to be heated in an atmosphere with a low oxygen concentration, which has a lower oxygen concentration than air. Therefore, even when heating the fiber-reinforced polyamide P at a high temperature above the melting point, deterioration of the fiber-reinforced polyamide P due to oxidation can be effectively suppressed.

[0036] Here, when heating the fiber-reinforced polyamide P that continuously passes through the heating furnace 31 as in this embodiment, the ε-caprolactam vaporized from the fiber-reinforced polyamide P fills the heating furnace 31. As a result, when the concentration of ε-caprolactam in the heating furnace 31 increases, it becomes difficult for ε-caprolactam to vaporize from the fiber-reinforced polyamide P (ε-caprolactam does not vaporize when the concentration exceeds a predetermined level).

[0037] In contrast, the heating furnace 31 of the present embodiment includes a supply port 33 for supplying superheated steam into it and an exhaust port 34 for exhausting the superheated steam supplied from the supply port 33 to the outside of the heating furnace 31. Therefore, unreacted ε-caprolactam vaporized from the fiber-reinforced polyamide P can be exhausted from the exhaust port 34 together with the superheated steam. As a result, while suppressing an increase in the concentration of ε-caprolactam in the heating furnace 31, ε-caprolactam can be removed more efficiently from the fiber-reinforced polyamide P continuously passing through the heating furnace 31.

[0038] Further, by heating the fiber-reinforced polyamide P with superheated steam, the fiber-reinforced polyamide P is more likely to be heated to the inside compared to the case where, for example, heated nitrogen gas is supplied into the heating furnace 31 for heating. Therefore, ε-caprolactam can be removed more efficiently from the fiber-reinforced polyamide P. Furthermore, heating with superheated steam is preferable also in terms of quick drying after heating.

[0039] Furthermore, by heating the fiber-reinforced polyamide P with superheated steam, the fiber-reinforced polyamide P is more likely to be heated to the inside compared to the case where, for example, an inert gas (e.g., nitrogen gas) is used. As a result, not only the surface of the fiber-reinforced polyamide P but also unreacted ε-caprolactam remaining inside can be removed efficiently.

[0040] In the present embodiment, ε-caprolactam (superheated steam) is exhausted from the exhaust port 34 using the supply pressure of the superheated steam into the heating furnace 31, but a configuration may also be adopted in which ε-caprolactam is sucked from the exhaust port 34 using a suction pump or the like. According to this configuration, it is possible to suppress the outflow of ε-caprolactam to the outside from the opening 32.

[0041] The ε-caprolactam (superheated steam) exhausted from the exhaust port 34 is supplied to the recovery unit 70 through the exhaust pipe 36. The recovery unit 70 is a cylindrical hopper (i.e., only the lower end is open) with its upper end closed. The recovery unit 70 is composed of a large-diameter portion 71 to which the exhaust pipe 36 is connected, a tapered portion 72 extending downward from the lower end of the large-diameter portion 71, and a small-diameter portion 73 extending downward from the lower end of the tapered portion 72. Both the large-diameter portion 71 and the small-diameter portion 73 are cylindrical, and the tapered portion 72 gradually decreases in diameter from the large-diameter portion 71 to the small-diameter portion 73.

[0042] The ε-caprolactam (superheated steam) supplied from the exhaust pipe 36 to the large-diameter portion 71 is liquefied by cooling in the large-diameter portion 71. The liquefied ε-caprolactam drips along the tapered portion 72 toward the small-diameter portion 73, so that the liquid ε-caprolactam (aqueous solution) can be recovered from the opening at the lower end of the small-diameter portion 73. Thereby, since the ε-caprolactam vaporized in the heating furnace 31 can be recovered by the recovery unit 70, it is possible to prevent the environment around the drawing forming apparatus 1 from being contaminated with ε-caprolactam.

[0043] The fiber-reinforced polyamide P from which ε-caprolactam has been removed by heating in the heating furnace 31 is cooled in the cooling unit 40 (see FIG. 1). In the present embodiment, the cooling in the cooling unit 40 is natural cooling, but a known cooling mechanism (for example, a cooling roller or a chamber that performs cooling with a fluid such as the heating furnace 31) may be used. By cooling in the cooling unit 40, the fiber-reinforced polyamide P (polyamide) solidifies, and the fiber-reinforced polyamide P from which ε-caprolactam has been removed is obtained.

[0044] Here, when removing ε-caprolactam by heating in the heating furnace 31, it is preferable that the thickness of the fiber-reinforced polyamide P is as thin as possible in order to rapidly heat to the inside of the fiber-reinforced polyamide P. On the other hand, if the fiber-reinforced polyamide P is too thin, it becomes difficult to mold (polymerize) into a desired shape (band shape) at the polymerization part 20. Therefore, at the polymerization part 20, it is preferable to polymerize the fiber-reinforced polyamide P with a thickness of 0.1 mm or more and 0.5 mm or less. Thereby, while making it easy to heat the fiber-reinforced polyamide P to the inside, the moldability of the fiber-reinforced polyamide P at the polymerization part 20 can be ensured.

[0045] Also, in the present embodiment, the fiber-reinforced polyamide P polymerized at the polymerization part 20 is heated in the heating furnace 31 in a sheet state, but for example, a configuration in which a strip-shaped prepreg Pr cut by a rotary cutter 60 (see FIG. 1) is heated may be used. However, in such a configuration, if the prepreg Pr is as thin as 0.5 mm or less as in the present embodiment, deformation such as warping is likely to occur during heating and cooling. Further, when heating the prepreg Pr, for example, when performing continuous heating, it is necessary to place it on a conveyor, so heating that melts the polyamide is substantially impossible.

[0046] On the other hand, in the present embodiment, the fiber-reinforced polyamide P heated in the heating furnace 31 is cooled in the cooling part 40 (see FIG. 1), and the fiber-reinforced polyamide P cooled in the cooling part 40 is pulled out in the pulling-out part 50. That is, since the heating in the heating furnace 31 and the cooling in the cooling part 40 are performed in a state where tension is applied to the fiber-reinforced polyamide P by the pulling of the pulling-out part 50, even if the thickness of the fiber-reinforced polyamide P is as thin as 0.5 mm or less, it is possible to suppress the occurrence of deformation such as warping in the fiber-reinforced polyamide P (prepreg Pr) after cooling. Therefore, the fiber-reinforced polyamide P (prepreg Pr) can be easily molded into a desired shape.

[0047] Furthermore, since heating is performed while the fiber-reinforced polyamide P is being pulled out by the pulling portion 50 (tension is applied to the fiber-reinforced polyamide P), unlike the case of heating the prepreg Pr after cutting, heating can be performed with the fiber-reinforced polyamide P floating. That is, the fiber-reinforced polyamide P can be heated in a non-contact state with other members without being placed on a conveyor or the like, so that heating can be performed until the fiber-reinforced polyamide P melts. As a result, ε-caprolactam becomes easier to vaporize, so that ε-caprolactam can be efficiently removed from the fiber-reinforced polyamide P.

[0048] Also, since the fiber-reinforced polyamide P contains a fiber material F at a volume content of 50% or more (60% in this embodiment), even when heated until the polyamide melts, the shape of the fiber-reinforced polyamide P is likely to be retained by the fiber material F. That is, it is possible to suppress the molten polyamide from flowing down between the fibers of the fiber material F, so that deformation of the fiber-reinforced polyamide P can be suppressed. Further, by including a fiber material F having a volume content of 75% or less in the fiber-reinforced polyamide P, the molding material C (ε-caprolactam) can be uniformly impregnated between the fibers in the impregnation portion 10 (see FIG. 1). Therefore, the fiber-reinforced polyamide P can be easily molded into a desired shape.

[0049] As described above, the present invention has been described based on the above embodiments. However, it can be easily inferred that the present invention is not limited to the above embodiments at all, and various modifications and improvements are possible without departing from the spirit of the present invention.

[0050] In the above embodiment, carbon fiber is exemplified as an example of the fiber material F, but it is not necessarily limited thereto. For example, as the fiber material F, known fiber materials such as glass fiber, metal fiber, aramid fiber, and silicon carbide fiber can be used, or a combination of these known fiber materials may be used.

[0051] In the above embodiment, ε-caprolactam was exemplified as an example of the lactam monomer, but it is not necessarily limited to this. Other examples of the lactam monomer include γ-butyrolactam, δ-valerolactam, ω-laurolactam, ω-decanolactam, ω-undecanolactam, and the like. That is, the lactam monomer is not limited to those exemplified above, and as long as it is a lactam monomer from which polyamide can be obtained by polymerization, the technical idea of the above embodiment can be applied.

[0052] In the above embodiment, hexamethylene diisocyanate was exemplified as the activator mixed with ε-caprolactam (molding material C), but it is not necessarily limited to this. For example, as the activator mixed with ε-caprolactam (molding material C), known activators such as hexamethylene diisocyanate, isocyanate and blocked isocyanate, isophthaloyl biscaprolactam, tetra-phthaloyl bis-caprolactam, esters such as dimethyl phthalate - polyethylene glycol, prepolymers of polyol or polydiene combined with bis acid chloride, and carbonyl biscaprolactam obtained by reacting phosgene with caprolactam can be used.

[0053] In the above embodiment, ε-caprolactam·sodium salt was exemplified as the polymerization catalyst mixed with ε-caprolactam (molding material C), but it is not necessarily limited to this. For example, as the polymerization catalyst mixed with ε-caprolactam (molding material C), known polymerization catalysts such as sodium caprolactamate, potassium caprolactamate and lithium caprolactamate, aluminum or magnesium caprolactam added with magnesium bromide, and alkoxide can be used.

[0054] In the above embodiment, the case where the fiber-reinforced polyamide P is heated by supplying superheated steam to the heating furnace 31 (under the gas flow of superheated steam) has been described, but it is not necessarily limited to this. For example, the fiber-reinforced polyamide P may be heated in an atmosphere of heated inert gas (nitrogen gas or argon gas) or another gas with a low oxygen concentration (preferably with an oxygen concentration of 20 vol% or less, more preferably 15 vol% or less), or in a vacuum. That is, it is preferable to heat the fiber-reinforced polyamide P in an atmosphere with a low oxygen concentration where the oxygen concentration is at least lower than that of air, but it may also be heated in an atmosphere containing oxygen (for example, in air).

[0055] In the above embodiment, the case where superheated steam is supplied from the supply port 33 of the heating furnace 31 and exhausted from the exhaust port 34 has been described, but it is not necessarily limited to this. For example, the supply port 33 and the exhaust port 34 may be omitted, and superheated steam may be supplied from the upstream opening 32 and exhausted from the downstream opening 32.

[0056] Also, the heating of the fiber-reinforced polyamide P may not be in a furnace surrounding the fiber-reinforced polyamide P such as the heating furnace 31. For example, a configuration may be adopted in which any one (or a plurality of surfaces) of the upper surface, lower surface, and side surface of the fiber-reinforced polyamide P is heated by a heater or a heating fluid, and the other surfaces are left open.

[0057] Also, instead of heating the fiber-reinforced polyamide P in a process before the drawing section 50, the fiber-reinforced polyamide P may be cut into the state of the prepreg Pr and then heated. When heating the prepreg Pr, a configuration in which it is continuously heated using a conveyor having a steel belt or a configuration in which it is batch-heated in an industrial oven or the like is exemplified (heating by these configurations can also be defined as heating in an "open system" where at least a part of the prepreg Pr is non-contact with other members). In any configuration, a configuration in which heating is performed in an atmosphere with a low oxygen concentration as in the above embodiment and a configuration in which vaporized ε-caprolactam is exhausted are preferable.

[0058] In the above embodiment, the case where ε-caprolactam exhausted from the exhaust port 34 is cooled and liquefied by the recovery unit 70 and recovered has been described, but it is not necessarily limited to this. For example, a configuration in which ε-caprolactam is solidified and recovered may be used, or a configuration in which the recovery unit 70 is omitted may be used.

[0059] In the above embodiment, the case where the fiber-reinforced polyamide P is polymerized with a thickness of 0.1 mm or more and 0.5 mm or less has been described, but it is not necessarily limited to this. For example, the fiber-reinforced polyamide P may be polymerized with a thickness less than 0.1 mm or exceeding 0.5 mm.

[0060] In the above embodiment, the case where the fiber-reinforced polyamide P contains the fiber material F at a volume content of 50% or more and 75% or less has been described, but it is not necessarily limited to this. For example, the fiber material F may be contained in the fiber-reinforced polyamide P at a volume content less than 50% or exceeding 75%.

Explanation of Signs

[0061] 1 Drawing forming apparatus 10 Impregnation part 20 Polymerization part 30 Heating part 31 Heating furnace 33 Supply port 34 Exhaust port 40 Cooling part 50 Drawing part 70 Recovery part F Fiber material P Fiber-reinforced polyamide

Claims

1. In a drawing forming apparatus for manufacturing fiber-reinforced polyamide by drawing forming, an impregnation section for impregnating a fiber material with a lactam monomer, a polymerization section for polymerizing the lactam monomer impregnated in the fiber material in the impregnation section to obtain fiber-reinforced polyamide, a heating section for heating the fiber-reinforced polyamide obtained in the polymerization section in an open system to vaporize unreacted lactam monomer, and comprising: the heating section includes a heating furnace in which a space for heating the fiber-reinforced polyamide in an atmosphere having a low oxygen concentration lower than that of air is formed inside, the heating furnace includes a supply port for supplying a gas having a low oxygen concentration into the heating furnace, and an exhaust port for exhausting the gas having a low oxygen concentration supplied into the heating furnace from the supply port to the outside of the heating furnace, in the heating furnace, the fiber-reinforced polyamide is heated at a temperature at which the polyamide of the fiber-reinforced polyamide melts and is 290 ° C or lower, and unreacted lactam monomer vaporized from the fiber-reinforced polyamide is exhausted from the exhaust port. A drawing forming apparatus characterized by that.

2. The drawing forming apparatus according to claim 1, wherein the gas having a low oxygen concentration is superheated steam.

3. The drawing forming apparatus according to claim 1 or 2, further comprising a recovery section for cooling the lactam monomer exhausted from the exhaust port and recovering the lactam monomer liquefied by the cooling.

4. The polymerization section polymerizes the lactam monomer to obtain fiber-reinforced polyamide having a thickness of 0.1 mm or more and 0.5 mm or less. The drawing forming apparatus according to any one of claims 1 to 3.

5. The drawing forming apparatus according to claim 4, further comprising a cooling section for cooling the fiber-reinforced polyamide heated in the heating section, and a drawing section for drawing the fiber-reinforced polyamide cooled in the cooling section.

6. The drawing forming apparatus according to claim 5, wherein the fiber-reinforced polyamide contains the fiber material in a volume content of 50% or more and 75% or less.

7. an impregnation step of impregnating a fiber material with a lactam monomer, a polymerization step of polymerizing the lactam monomer impregnated in the fiber material in the impregnation step to obtain fiber-reinforced polyamide, a heating step of heating the fiber-reinforced polyamide obtained in the polymerization step in an open system to vaporize unreacted lactam monomer, and comprising: In the heating step, a heating furnace is used in which a space for heating the fiber-reinforced polyamide is formed inside in an atmosphere with a low oxygen concentration that is lower than that of air. The heating furnace includes a supply port for supplying a gas with a low oxygen concentration into the heating furnace, and an exhaust port for exhausting the gas with a low oxygen concentration supplied into the heating furnace from the supply port to the outside of the heating furnace. In the heating furnace, the fiber-reinforced polyamide is heated at a temperature at which the polyamide of the fiber-reinforced polyamide melts and is 290°C or lower, and unreacted lactam monomer vaporized from the fiber-reinforced polyamide is exhausted from the exhaust port. A method for producing a fiber-reinforced polyamide, characterized by this.

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