Sheet formed from carbon fiber reinforced thermoplastic resin, and production method of said sheet

Abstract

A sheet formed from a carbon fiber reinforced thermoplastic resin with a simplified production process and excellent mechanical characteristics, and a production method of said sheet is provided. This sheet is formed from a carbon fiber reinforced thermoplastic resin that contains carbon fibers, dichloromethane, and a thermoplastic resin containing at least one of a polycarbonate resin and a polyarylate resin, and the content of the dichloromethane contained in the sheet is 10-10,000 ppm by mass.

Claims

1. A method for producing a carbon fiber reinforced thermoplastic resin sheet, the method comprising: producing a thermoplastic resin solution wherein a thermoplastic resin containing a polycarbonate resin has been dissolved in dichloromethane by an interfacial polymerization process; impregnating the thermoplastic resin solution into carbon fibers; and evaporating dichloromethane from the carbon fibers impregnated with the thermoplastic resin solution, wherein the producing a thermoplastic resin solution comprises (i) mixing reactants including a dihydric phenol and phosgene or triphosgene in the presence of the dichloromethane and an alkaline aqueous solution, (ii) thereafter adding a polymerization catalyst into the reactants to carry out the interfacial polymerization process, and (iii) purifying the resulting resin solution to give the thermoplastic resin solution.

2. The production method according to claim 1, wherein a concentration of the polycarbonate resin in the thermoplastic resin solution is 10-30 mass %.

3. The production method according to claim 1, wherein the dihydric phenol is represented by formula (1) below: ##STR00003## in formula (1), R.sub.1-R.sub.4 each independently represent hydrogen, a halogen, a nitro, an optionally substituted C1-C20 alkyl group, an optionally substituted C1-C5 alkoxy group, an optionally substituted C6-C12 aryl group, an optionally substituted C7-C17 aralkyl group or an optionally substituted C2-C15 alkenyl group; and X is —O—, —S—, —SO—, —SO.sub.2—, —CO— or a divalent group represented by any of Formulae (2) to (5) below: ##STR00004## in Formula (2), R.sub.5 and R.sub.6 each independently represent hydrogen, a halogen, an optionally substituted C1-C20 alkyl group, an optionally substituted C1-C5 alkoxy group, an optionally substituted C6-C12 aryl group, an optionally substituted C7-C17 aralkyl group or an optionally substituted C2-C15 alkenyl group, or R.sub.5 and R.sub.6 bond with each other to form a C3-C20 carbon ring or a C1-C20 heterocyclic ring; in Formula (3), R.sub.7 and R.sub.8 each independently represent hydrogen, a halogen, an optionally substituted C1-C20 alkyl group, an optionally substituted C1-C5 alkoxy group, an optionally substituted C6-C12 aryl group, an optionally substituted C7-C17 aralkyl group or an optionally substituted C2-C15 alkenyl group, or R.sub.7 and R.sub.8 bond with each other to form a C3-C20 carbon ring or a C1-C20 heterocyclic ring; in Formula (4), R.sub.9-R.sub.12 each independently represent hydrogen, a halogen, an optionally substituted C1-C20 alkyl group, an optionally substituted C1-C5 alkoxy group, an optionally substituted C6-C12 aryl group, an optionally substituted C7-C17 aralkyl group or an optionally substituted C2-C15 alkenyl group; and in Formula (5), R.sub.13-R.sub.22 each independently represent a hydrogen atom or a C1-C3 alkyl group, where at least one of R.sub.13-R.sub.22 is a C1-C3 alkyl group.

4. The production method according to claim 1, wherein a content of dichloromethane contained in the carbon fiber reinforced thermoplastic resin sheet is 10-10,000 ppm by mass.

5. The production method according to claim 1, wherein the carbon fibers are continuous fibers.

6. The production method according to claim 1, wherein the carbon fiber reinforced thermoplastic resin sheet comprises the carbon fibers for 20-80 vol % and the thermoplastic resin for 80-20 vol %.

7. The production method according to claim 1, wherein a viscosity-average molecular weight of the polycarbonate resin after the interfacial polymerization process is 10,000-100,000.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described specifically by way of examples and comparative examples. The embodiments may appropriately be altered as long as the effect of the invention is achieved.

(2) <Conditions for Measuring Viscosity-Average Molecular Weight (Mv)>

(3) Measurement instrument: Ubbelohde capillary viscometer

(4) Solvent: Dichloromethane

(5) Concentration of resin solution: 0.5 grams/deciliter

(6) Measurement temperature: 25° C.

(7) Subsequent to a measurement under the above conditions, the intrinsic viscosity [η] deciliter/gram is determined at a Huggins coefficient of 0.45 to calculate the viscosity-average molecular weight by the following equation.
Θ=1.23×10.sup.−4×Mv.sup.0.83
<Conditions for Measuring Content of Dichloromethane (MC)>

(8) Measurement instrument: Gas chromatograph (GC-2014 manufactured by Shimadzu Corporation)

(9) Solvent: Chloroform

(10) Concentration of carbon fiber reinforced thermoplastic resin solution: 2 grams/20 milliliters

(11) Sample vaporization chamber: 200° C., 252 kPa

(12) Column: 60° C. at the start of measurement, 120° C. at the end of measurement, measurement time 10 minutes

(13) Detector: 320° C.

(14) Subsequent to a measurement under the above conditions, a peak area at a retention time of 4.4 minutes was determined to calculate the content of dichloromethane based on the separately calculated calibration curve. The dichloromethane content of less than 10 ppm by mass was considered N.D.

(15) <Conditions for Measuring Carbon Fiber Content (Vf)>

(16) The carbon fiber content (Vf) was measured based on JIS K 7075.

(17) <Drop Weight Impact Test>

(18) Instrument used: CEAST9350 manufactured by Instron

(19) Striker: 10 mmφ, 5.136 kg

(20) Sample support: 40 mmφ

Example 1

(21) (Step of Producing Polycarbonate Resin Solution)

(22) 7.5 kg (32.89 mol) of bisphenol A (BPA) manufactured by Nippon Steel and Sumikin Chemical and 30 g of hydrosulfite as an antioxidant were added to and dissolved in 54 kg of a 9 m/m % aqueous sodium hydroxide solution. To this, 40 kg of dichloromethane was added, and 4.4 kg of phosgene was blown into the resultant by spending 30 minutes while stirring and keeping the solution temperature in a range of 15° C.−25° C.

(23) After the phosgene blowing, 2 kg of a 9 m/m % aqueous sodium hydroxide solution, 7.5 kg of dichloromethane, and a solution obtained by dissolving 193.5 g (1.29 mol) of p-tert-butylphenol in 1 kg of dichloromethane were added and vigorously stirred for emulsification. Thereafter, 10 ml of triethylamine as a polymerization catalyst was added to allow polymerization for about 40 minutes.

(24) The polymerization solution was separated into a water phase and an organic phase, the organic phase was neutralized with phosphoric acid and repeatedly rinsed with pure water until the pH of the rinsing solution became neutral. The concentration of the purified polycarbonate resin solution was 15 mass %.

(25) The resulting polycarbonate resin solution was used to measure the viscosity-average molecular weight, which turned out to be 21,500.

(26) (Impregnating and Drying Steps)

(27) A carbon fiber textile (TORAYCA cloth CO6347B manufactured by Toray Industries) was cut into a size of 10 cm×10 cm, which was impregnated with the polycarbonate resin solution in an impregnation tank. At the end of the impregnation, the resultant was dried in a thermostatic chamber at 25° C. for 5 hours, and then dried in a hot air dryer at 100° C. for an hour to give a carbon fiber reinforced thermoplastic resin.

(28) The carbon fiber content (Vf) of the resulting carbon fiber reinforced thermoplastic resin was 57 vol %. The resulting carbon fiber reinforced thermoplastic resin was used to measure the dichloromethane content, which turned out to be 50 ppm by mass. The thickness of the resulting carbon fiber reinforced thermoplastic resin was 0.268 mm. The results are summarized in Table 1.

(29) (Evaluation of Appearance after Molding)

(30) The resulting carbon fiber reinforced thermoplastic resin was pressed at 100 kgf for 5 minutes while being heated at 265° C. to obtain a sheet for evaluating the appearance.

(31) No void was found in the resulting sheet for evaluating the appearance, and thus the appearance was “good”.

(32) (Heat Pressing Step)

(33) Five sheets of the resulting carbon fiber reinforced thermoplastic resin were laminated and pressed for 15 minutes while being heated at 265° C. to give a laminate sheet of the carbon fiber reinforced thermoplastic resin.

(34) (Evaluation of Mechanical Characteristics)

(35) A 60 mm square piece was cut out from the resulting laminate sheet of the carbon fiber reinforced thermoplastic resin with a cross saw to perform a drop weight impact test, where the fracture energy was 4.47 J, the maximum stress was 874 N, and no separation was observed between the layers at the fractured site. The results are summarized in Table 1.

Example 2

(36) (Steps of Producing Polycarbonate Resin Solution, Impregnating and Drying)

(37) A carbon fiber reinforced thermoplastic resin was obtained by using the polycarbonate resin solution obtained in Example 1 and operating in the same manner as Example 1 except that drying was conducted in a hot air dryer at 100° C. for an hour (in other words, drying was not conducted in a thermostatic chamber at 25° C. for 5 hours at the end of the impregnation).

(38) The carbon fiber content (Vf) of the resulting carbon fiber reinforced thermoplastic resin was 52 vol %. The resulting carbon fiber reinforced thermoplastic resin was used to measure the dichloromethane content, which turned out to be 120 ppm by mass. The thickness of the resulting carbon fiber reinforced thermoplastic resin was 0.261 mm. The results are summarized in Table 1.

(39) (Evaluation of Appearance after Molding)

(40) The resulting carbon fiber reinforced thermoplastic resin was pressed at 100 kgf for 5 minutes while being heated at 265° C. to obtain a sheet for evaluating the appearance.

(41) No void was found in the resulting sheet for evaluating the appearance, and thus the appearance was “good”.

Example 3

(42) (Steps of Producing Polycarbonate Resin Solution, Impregnating and Drying)

(43) A carbon fiber reinforced thermoplastic resin was obtained by using the polycarbonate resin solution obtained in Example 1 and operating in the same manner as Example 1 except that drying was not conducted in a hot air dryer (in other words, drying was conducted only in a thermostatic chamber at 25° C. for 5 hours at the end of the impregnation).

(44) The carbon fiber content (Vf) of the resulting carbon fiber reinforced thermoplastic resin was 52 vol %. The resulting carbon fiber reinforced thermoplastic resin was used to measure the dichloromethane content, which turned out to be 4,680 ppm by mass. The thickness of the resulting carbon fiber reinforced thermoplastic resin was 0.271 mm. The results are summarized in Table 1.

(45) (Evaluation of Appearance after Molding)

(46) The resulting carbon fiber reinforced thermoplastic resin was pressed at 100 kgf for 5 minutes while being heated at 265° C. to obtain a sheet for evaluating the appearance.

(47) No void was found in the resulting sheet for evaluating the appearance, and thus the appearance was “good”.

Comparative Example 1

(48) (Step of Producing Polycarbonate Resin Powder)

(49) The polycarbonate resin solution obtained in Example 1 was dropped in warm water for granulation, and dehydrated with a solid-liquid separator. Thereafter, the remaining solvent was evaporated in a dryer to obtain polycarbonate resin powder.

(50) (Step of Producing Polycarbonate Film)

(51) The resulting polycarbonate resin powder was subjected to extrusion using a twin-screw kneader TEM26DS manufactured by Toshiba Machine (screw diameter: 28.2 mm, extruder temperature: 270° C., die width: 330 mm, die temperature: 270° C.) to give a 50 μm thick film.

(52) (Heat Pressing Step)

(53) The resulting film and a carbon fiber textile (TORAYCA cloth CO6347B manufactured by Toray Industries) were cut into a size of 10 cm×10 cm, respectively, and five each of them were alternately laminated and pressed for 15 minutes while being heated at 265 C to give a laminate sheet of a carbon fiber reinforced thermoplastic resin.

(54) The carbon fiber content (Vf) of the laminate sheet of the carbon fiber reinforced thermoplastic resin was 56 vol %.

(55) (Evaluation of Mechanical Characteristics)

(56) A 60 mm square piece was cut out from the laminate sheet of the carbon fiber reinforced thermoplastic resin with a cross saw to perform a drop weight impact test, where the fracture energy was 4.05 J, the maximum stress was 829 N, and separation was observed between the layers at the fractured site. The results are summarized in Table 1.

Comparative Example 2

(57) (Steps of Producing Polycarbonate Resin Solution, Impregnating and Drying)

(58) A carbon fiber reinforced thermoplastic resin was obtained by using the polycarbonate resin solution obtained in Example 1 and operating in the same manner as Example 1 except that drying was conducted in a thermostatic chamber at 25° C. for 2 hours without drying in a hot air dryer.

(59) The carbon fiber content (Vf) of the resulting carbon fiber reinforced thermoplastic resin was 58 vol %. The resulting carbon fiber reinforced thermoplastic resin was used to measure the dichloromethane content, which turned out to be 12,530 ppm by mass. The thickness of the resulting carbon fiber reinforced thermoplastic resin was 0.252 mm. The results are summarized in Table 1.

(60) (Evaluation of Appearance after Molding)

(61) The resulting carbon fiber reinforced thermoplastic resin was pressed at 100 kgf for 5 minutes while being heated at 265° C. to obtain a sheet for evaluating the appearance.

(62) Voids were found in the resulting sheet for evaluating the appearance, and thus the appearance was “poor”.

(63) TABLE-US-00001 TABLE 1 Evaluation of Maximum Constituent Viscosity-average Vf MC content Thickness appearance Fracture E stress Example unit molecular weight Drying conditions [%] [ppm] [mm] after molding [J] [N] Example 1 BPA 21,500 25° C./5 hr, 100° C./1 hr 57 50 0.268 Good 4.47 874 Example 2 BPA 21,500 100° C./1 hr  52 120 0.261 Good — — Example 3 BPA 21,500 25° C./5 hr 52 4,680 0.271 Good — — Comparative BPA 21,500 — 56 N.D. — — 4.05 829 example 1 Comparative BPA 21,500 25° C./2 hr 58 12,530 0.252 Poor — — example 2