METHOD FOR MANUFACTURING CONTINUOUS FIBER-REINFORCED THERMOPLASTIC RESIN SHEET

Abstract

A manufacturing method can be carried out using simple equipment and makes it possible to efficiently manufacture many continuous fiber-reinforced thermoplastic resin sheets in a short period of time. The above problem is overcome by a method for manufacturing a continuous fiber-reinforced thermoplastic resin sheet including: an impregnation step for impregnating continuous fiber with a thermoplastic resin solution containing a halogen-containing organic solvent and a thermoplastic resin containing at least one resin from among polycarbonate resins and polyarylate resins; and a solvent removal step for removing, under exposure to IR radiation, the halogen-containing organic solvent from the continuous fiber impregnated with the thermoplastic resin solution. In the solvent removal step, the distance between a heater for emitting the IR radiation and the continuous fiber is 400 mm or less, and the temperature of a heating element for radiating the IR radiation in the heater is 260 C. or higher.

Claims

1. A method for producing a continuous fiber-reinforced thermoplastic resin sheet, the method comprising: an impregnation step for impregnating a continuous fiber with a thermoplastic resin solution comprising a halogen-containing organic solvent and a thermoplastic resin comprising at least one of a polycarbonate resin and a polyarylate resin; and a solvent removal step for removing, by means of infrared irradiation, the halogen-containing organic solvent from the continuous fiber impregnated with the thermoplastic resin solution, wherein in the solvent removal step, the distance between a heater for said infrared irradiation and the continuous fiber is 400 mm or less, and the temperature of a heating element for said infrared irradiation in the heater is 260 C. or higher.

2. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to claim 1, wherein the halogen-containing organic solvent comprises dichloromethane.

3. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to claim 1 or 2, wherein in the solvent removal step, the distance between the heater and the continuous fiber is from 100 mm to 410 mm.

4. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 3, wherein in the solvent removal step, the temperature of the heating element in the heater is from 300 C. to 400 C.

5. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 4, wherein in the solvent removal step, the heater irradiates far infrared rays including a wavelength range of from 2 m to 20 m.

6. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 5, wherein the concentration of the thermoplastic resin in the thermoplastic resin solution is 10 to 30% by mass.

7. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 6, wherein in the impregnation step, the rate for impregnating the continuous fiber with the thermoplastic resin solution is from 0.3 m/min to 3.0 m/min.

8. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 7, wherein in the solvent removal step, the time for said infrared irradiation is from 2 minutes to 15 minutes.

9. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 8, wherein the ratio of the thermoplastic resin in the continuous fiber-reinforced thermoplastic resin sheet is 15 to 50% by mass.

10. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 9, wherein the content of the halogen-containing organic solvent remaining in the continuous fiber-reinforced thermoplastic resin sheet is less than 1000 mass ppm.

11. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 10, wherein the thermoplastic resin has a structural unit derived from a dihydric phenol represented by general formula (1): ##STR00005## wherein in general formula (1): R.sub.1 to R.sub.4 each independently represent hydrogen, halogen, a nitro group, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 5 carbon atoms which may have a substituent, an aryl group having 6 to 12 carbon atoms which may have a substituent, an aralkyl group having 7 to 17 carbon atoms which may have a substituent, or an alkenyl group having 2 to 15 carbon atoms which may have a substituent; and X is O, S, SO, SO.sub.2, CO, or a divalent group represented by any of formulae (2) to (5): ##STR00006## wherein in formula (2): R.sub.5 and R.sub.6 each independently represent hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 5 carbon atoms which may have a substituent, an aryl group having 6 to 12 carbon atoms which may have a substituent, an aralkyl group having 7 to 17 carbon atoms which may have a substituent, or an alkenyl group having 2 to 15 carbon atoms which may have a substituent, or alternatively, R.sub.5 and R.sub.6 are bonded to each other to form a carbocyclic ring having 3 to 20 carbon atoms or a heterocyclic ring having 1 to 20 carbon atoms; and c represents an integer of 0 to 20, and wherein in formula (3): R.sub.7 and R.sub.8 each independently represent hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 5 carbon atoms which may have a substituent, an aryl group having 6 to 12 carbon atoms which may have a substituent, an aralkyl group having 7 to 17 carbon atoms which may have a substituent, or an alkenyl group having 2 to 15 carbon atoms which may have a substituent, or alternatively, R.sub.7 and R.sub.8 are bonded to each other to form a carbocyclic ring having 3 to 20 carbon atoms or a heterocyclic ring having 1 to 20 carbon atoms, and wherein in formula (4): R.sub.9 to R.sub.12 each independently represent hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 5 carbon atoms which may have a substituent, an aryl group having 6 to 12 carbon atoms which may have a substituent, an aralkyl group having 7 to 17 carbon atoms which may have a substituent, or an alkenyl group having 2 to 15 carbon atoms which may have a substituent; the substituents are each independently halogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 12 carbon atoms; and R.sub.9 and R.sub.10, and R.sub.11 and R.sub.12, respectively, may be bonded to each other to form a carbocyclic ring having 3 to 20 carbon atoms or a heterocyclic ring having 1 to 20 carbon atoms, and wherein in formula (5): R.sub.13 to R.sub.22 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R.sub.13 to R.sub.22 is an alkyl group having 1 to 3 carbon atoms.

12. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 11, which further has a solution production step for producing a thermoplastic resin solution by dissolving the thermoplastic resin in the halogen-containing organic solvent.

13. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 12, which further has a measurement step for measuring the content of the halogen-containing organic solvent remaining in the continuous fiber-reinforced thermoplastic resin sheet after the solvent removal step.

14. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 13, which further has a comparison step for comparing the content of the halogen-containing organic solvent remaining in the continuous fiber-reinforced thermoplastic resin sheet with a predetermined threshold after the solvent removal step.

15. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 14, wherein the continuous fiber is any of a single strand, a unidirectional sheet, and a fabric.

16. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 15, wherein the continuous fiber is any of a carbon fiber, a glass fiber, and an aramid fiber.

17. The method for producing a continuous fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 16, wherein the continuous fiber-reinforced thermoplastic resin sheet is a prepreg.

Description

EXAMPLES

<Resin Mass Content>

[0119] The resin mass content of each carbon fiber-reinforced resin prepreg obtained in Examples and Comparative Examples described later was calculated based on the fiber mass content obtained based on JIS K 7075. Specifically, a value (% by mass) obtained by subtracting a value of the fiber mass content (% by mass) of each carbon fiber-reinforced resin prepreg from 100(%) was regarded as the resin mass content.

<Amount of Remaining Dichloromethane (Ppm)>

[0120] Each carbon fiber-reinforced resin prepreg obtained in Examples and Comparative Examples described later was cut into a size of 6.0 cm4.0 cm, and it was dissolved in 20 ml of chloroform to extract dichloromethane in the sample. After extraction, filtration was carried out using a 0.45 m filter (RJF3245NH) to obtain a sample for gas chromatography.

[0121] GC analysis was carried out under the below-described conditions, the peak area (retention time: 4.7 minutes) was determined, and the content of dichloromethane was calculated using a calibration curve.

[0122] Measurement apparatus: Gas chromatograph (GC-2014 manufactured by Shimadzu Corporation)

[0123] Solvent: chloroform

[0124] Sample vaporizing chamber: 200 C., 252 kPa

[0125] Column temperature and time: 60 C. at the start of measurement, 120 C. at the end of measurement, 10 minutes of measurement time

[0126] Temperature of detector: 320 C.

<Production Example 1: Production Example of Polycarbonate Resin (PC-1)>

[0127] 6.5 kg (28.47 mol) of bisphenol A (BPA) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. and 30 g of hydrosulfite as an antioxidant were added to and dissolved in 40 kg of 9 mass/mass % (or w/w %) aqueous solution of sodium hydroxide. 17 kg of dichloromethane was added to the solution thus obtained, and 3.7 kg of phosgene was injected into the solution over 30 minutes while stirring with the solution temperature being kept at 15 C. to 25 C.

[0128] To the reaction solution after the completion of injection of phosgene, a solution obtained by dissolving 3 kg of 9% (m/m) aqueous solution of sodium hydroxide, 16 kg of dichloromethane, and 167.7 g (1.12 mol) of p-tert-butylphenol in 1 kg of dichloromethane in advance was added, and the mixture was vigorously stirred to be emulsified. After that, 10 ml of triethylamine as a polymerization catalyst was further added to the reaction solution, and a polymerization reaction was performed for about 40 minutes.

[0129] The polymerization solution thus obtained was separated into an aqueous phase and an organic phase, and the organic phase was neutralized with phosphoric acid and repeatedly washed with pure water until the pH of the washing solution became neutral. The obtained polymer solution was added dropwise to warm water with its temperature being kept at 47 C., and the solvent was removed by evaporation to obtain a white powdery precipitate. The obtained precipitate was filtered and dried at 105 C. for 24 hours to obtain a polycarbonate resin (PC-1). The obtained polycarbonate resin (PC-1) was used in Examples and Comparative Examples described below.

[0130] The viscosity average molecular weight of the obtained polycarbonate resin (PC-1) was measured, and it was 21,500.

<Production Example 2: Production Example of Polycarbonate Resin (PC-2)>

[0131] 6.7 kg (23.10 mol) of 1,1-bis(4-hydroxyphenyl)-1-phenylethane (BPAP) manufactured by Honshu Chemical Industry Co., Ltd. and 40 g of hydrosulfite as an antioxidant were added to and dissolved in 36 kg of 9% (w/w) aqueous solution of sodium hydroxide. 16 kg of dichloromethane was added to the solution thus obtained, and 3.2 kg of phosgene was injected into the solution over 30 minutes while stirring with the solution temperature being kept at 15 C. to 25 C.

[0132] To the reaction solution after the completion of injection of phosgene, a solution obtained by dissolving 13 kg of dichloromethane and 132.8 g (0.89 mol) of p-tert-butylphenol in 1 kg of dichloromethane in advance was added, and the mixture was vigorously stirred to be emulsified. After that, 15 ml of triethylamine as a polymerization catalyst was further added to the reaction solution, and a polymerization reaction was performed for about 40 minutes.

[0133] The polymerization solution thus obtained was separated into an aqueous phase and an organic phase, and the organic phase was neutralized with phosphoric acid and repeatedly washed with pure water until the pH of the washing solution became neutral. The obtained polymer solution was added dropwise to warm water with its temperature being kept at 60 C., and the solvent was removed by evaporation to obtain a white powdery precipitate. The obtained precipitate was filtered and dried at 120 C. for 24 hours to obtain a polycarbonate resin (PC-2). The obtained polycarbonate resin (PC-2) was used in Examples and Comparative Examples described below.

[0134] The viscosity average molecular weight of the obtained polycarbonate resin (PC-2) was measured, and it was 21,000.

<Method for Measurement of Viscosity Average Molecular Weight>

[0135] The method for measurement and calculation of values of the viscosity average molecular weight (Mv) is as described below.

[0136] Measurement apparatus: Ubbelohde capillary viscometer

[0137] Solvent: dichloromethane

[0138] Concentration of resin solution: 0.5 gram/deciliter

[0139] Measurement temperature: 25 C.

[0140] The measurement was carried out under the above-described conditions to determine a limiting viscosity [] deciliter/gram with a Huggins constant of 0.45, and calculation was made according to formula (1) below.

[00001]$\begin{array}{cc}=1.2310^{-4}{\mathrm{Mv}}^{0.83}& \left(1\right)\end{array}$

Example 1

[0141] 15 parts by mass of the polycarbonate resin (PC-1) was dissolved in 85 parts by mass of dichloromethane to prepare a polycarbonate resin solution.

[0142] A 2/2 twill carbon fiber fabric made by using a continuous carbon fiber derived from polyacrylonitrile (Torayca (registered trademark) Cloth C06347B manufactured by Toray Industries, Inc.) was cut into a size of 6.0 cm16.0 cm (thickness: 0.22 mm, weight: 198 g/m.sup.2), and it was impregnated with the polycarbonate resin solution at a pull-up rate of 0.6 m/min using a dip coater. A pair of panels of afar infrared heater (Electric Ceramic Heater PLC (PLC-328) manufactured by Noritake Co., Ltd.) were respectively opposed to each of the surfaces of the carbon fiber fabric after impregnation as a prepreg intermediate material (prepreg base material), and the prepreg intermediate material was dried for 5 minutes to obtain a carbon fiber-reinforced thermoplastic resin prepreg. The far infrared heater was surrounded by an aluminum board, the distance between the heater panel and the prepreg base material and the heater temperature were set as described in Table 1, and the solvent removal step was carried out.

[0143] In the solvent removal step, the area of the surface for irradiating infrared rays of one panel of the far infrared heater was 0.0144 m.sup.2 (12 cm12 cm), and 4 panels of the far infrared heater were used and respectively opposed to each of the front sides and back sides of 2 prepreg intermediate materials which were arranged side by side along approximately the same plane. The impregnated portion of said 2 prepreg intermediate materials, i.e., the surface to be dried for removing the solvent was 0.0060 m.sup.2 (10 cm6 cm). Accordingly, the ratio of the area of the surface for irradiating far infrared rays of the heater panel to the area of the surface of the continuous fiber to be dried (area of surface to be dried (m.sup.2)/area of surface for irradiating far infrared rays (m.sup.2)100(%)) was about 41.7%.

[0144] Further, the electric capacity of the far infrared heater panel was 800 W and the area of the surface for irradiating infrared rays was 0.0144 m.sup.2 as described above, and accordingly, the value of the maximum energy density calculated was 55.6 kW/m.sup.2 (0.8 kW/0.0144 m.sup.2).

[0145] As described above, in Example 1, a pair of the far infrared heater panels were used, and in this regard, the prepreg base material was allowed to stand at the middle point between the pair of the far infrared heater panels. Accordingly, the values in the column of Distance between heater and prepreg base material in Table 1 mean the distance between the surface of the prepreg base material (surface to be dried) and any one of the far infrared heater panels. The same applies to Table 2.

[0146] Further, the values in the column of Infrared heater temperature in Table 1 mean the temperature of a heating element for infrared irradiation in the heater. The same applies to Table 2.

[0147] As shown in the tables below, in Examples, the infrared heater temperatures were 300 to 400 C., and the peak wavelengths of irradiated far infrared rays calculated based on Wien's displacement law with respect to the far infrared heater panels used were about 4.96 to 4.21 m. Further, in Comparative Examples, the infrared heater temperatures were 250 to 300 C., and the peak wavelengths of irradiated far infrared rays were about 5.43 to 4.96 m.

[0148] The resin mass content of the obtained carbon fiber-reinforced resin prepreg (continuous fiber-reinforced thermoplastic resin sheet) was 33% by mass. The content of dichloromethane in the prepreg was measured, and it was 100 mass ppm.

[0149] The evaluation results are shown in Table 1.

Examples 2 to 14, Examples 1-1 to 1-7, Comparative Examples 1 to 4

[0150] A carbon fiber-reinforced resin prepreg was prepared in a manner similar to that in Example 1, except that any of the type of the polycarbonate resin, the distance between the heater panel and the prepreg base material, and the heater temperature was changed as described in Table 1, and evaluation was carried out.

[0151] The evaluation results are shown in Table 1 or Table 2. The results of Examples 1-1 to 1-7 are shown in Table 2 together with the above-described results of Example 1 which are included in both Tables 1 and 2.

Comparative Example 5

[0152] Impregnation with a polycarbonate resin solution was carried out in a manner similar to that in Example 1. After impregnation, drying was carried out for 5 minutes in a multistage hot air dryer, thereby obtaining a carbon fiber-reinforced resin prepreg.

[0153] The evaluation results are shown in Table 1.

TABLE-US-00001 TABLE 1 Production conditions Distance between Infrared Hot air heater and prepreg heater temperature of Drying base material temperature hot air dryer PC resin method [mm] [ C.] [ C.] Example 1 PC-1 Infrared 225 300 rays Example 2 PC-1 Infrared 225 350 rays Example 3 PC-1 Infrared 300 300 rays Example 4 PC-1 Infrared 300 350 rays Example 5 PC-1 Infrared 375 300 rays Example 6 PC-1 Infrared 375 350 rays Example 7 PC-2 Infrared 225 350 rays Example 8 PC-2 Infrared 225 400 rays Example 9 PC-2 Infrared 300 350 rays Example 10 PC-2 Infrared 300 400 rays Example 11 PC-2 Infrared 375 350 rays Example 12 PC-2 Infrared 375 400 rays Example 13 PC-2 Infrared 225 300 rays Example 14 PC-2 Infrared 300 300 rays Comparative PC-1 Infrared 225 250 Example 1 rays Comparative PC-1 Infrared 300 250 Example 2 rays Comparative PC-1 Infrared 375 250 Example 3 rays Comparative PC-1 Infrared 420 300 Example 4 rays Comparative PC-2 Hot air 140 Example 5 type Physical properties of Production conditions thermoplastic resin sheet Concentration Amount of of resin Impregnation Drying Resin mass remaining solution rate time content dichloromethane [% by mass] [m/min] [min] [% by mass] [mass ppm] Example 1 15% 0.6 5 33% 100 Example 2 15% 0.6 5 33% 20 Example 3 15% 0.6 5 33% 100 Example 4 15% 0.6 5 33% 30 Example 5 15% 0.6 5 33% 150 Example 6 15% 0.6 5 33% 20 Example 7 15% 0.6 5 33% 60 Example 8 15% 0.6 5 33% 50 Example 9 15% 0.6 5 33% 80 Example 10 15% 0.6 5 33% 110 Example 11 15% 0.6 5 33% 80 Example 12 15% 0.6 5 33% 30 Example 13 15% 0.6 5 33% 220 Example 14 15% 0.6 5 33% 870 Comparative 15% 0.6 5 33% 1580 Example 1 Comparative 15% 0.6 5 33% 3650 Example 2 Comparative 15% 0.6 5 33% 4040 Example 3 Comparative 15% 0.6 5 33% 1280 Example 4 Comparative 15% 0.6 5 33% 1560 Example 5

TABLE-US-00002 TABLE 2 Production conditions Distance between Infrared Hot sir heater and prepreg heater temperature of Drying base material temperature hot air dryer PC resin method [mm] [ C.] [ C.] Example 1 PC-1 Infrared 225 300 rays Example 1-1 PC-1 Infrared 225 300 rays Example 1-2 PC-1 Infrared 225 300 rays Example 1-3 PC-1 Infrared 225 300 rays Example 1-4 PC-1 Infrared 225 300 rays Example 1-5 PC-1 Infrared 225 300 rays Example 1-6 PC-1 Infrared 225 350 rays Example 1-7 PC-1 Infrared 225 300 rays Physical properties of Production conditions thermoplastic resin sheet Concentration Amount of of resin Impregnation Drying Resin mass remaining solution rate time content dichloromethane [% by mass] [m/min] [min] [% by mass] [mass ppm] Example 1 15% 0.6 5 33% 100 Example 1-1 15% 0.3 5 30% 140 Example 1-2 15% 1.0 5 35% 60 Example 1-3 15% 1.5 5 38% 80 Example 1-4 13% 0.6 5 25% 40 Example 1-5 15% 0.6 3 33% 180 Example 1-6 15% 0.6 3 33% N.D. Example 1-7 15% 0.6 10 33% N.D.

[0154] As is clear from the results of Examples and Comparative Examples shown in Table 1, it was confirmed that the solvent can be efficiently removed from the intermediate material (prepreg intermediate material/prepreg base material) that is the continuous fiber containing the halogen-containing organic solvent when infrared rays are irradiated (see Examples and Comparative Example 5).

[0155] Further, it was confirmed that the continuous fiber was more efficiently dried in Examples in which the conditions in the solvent removal step including the distance between the heater for infrared irradiation and the surface of the continuous fiber to be dried, the infrared heater temperature, and the drying time were adjusted, and that the continuous fiber was even more efficiently dried by adjusting the conditions in the impregnation step, which was performed before the solvent removal step, including the concentration of the resin solution and the impregnation rate (see Table 1 and Table 2).

[0156] Moreover, it was confirmed that the solvent was efficiently removed not only in Examples in which the bisphenol-based polycarbonate resin (PC-1) was used, but also in Examples in which the bisphenol AP-based polycarbonate resin (PC-2), which is usually not easily dried, was used.