Polyarylate and molded article using same

Abstract

The present invention can provide a polyarylate obtained from a dihydric phenol component and an aromatic dicarboxylic acid component. The polyarylate is characterized in that the dihydric phenol component contains a compound represented by general formula (A) or (B) as a primary raw material, and the pencil hardness of the polyarylate is H or higher. ##STR00001## (In the formula, R.sub.1 and R.sub.2 each independently denote a hydrogen atom, an alkyl group having 1-6 carbon atoms or a phenyl group. However, neither R.sub.1 nor R.sub.2 represents a methyl group.) ##STR00002## (In the formula, R.sub.3 and R.sub.4 each independently denote a hydrogen atom or a methyl group. In addition, a is an integer between 4 and 11. However, a is not 5 if R.sub.3 and R.sub.4 are both hydrogen atoms.)

Claims

1. A molded article obtained by injection molding or extrusion molding a polyarylate obtained from a dihydric phenol component and an aromatic dicarboxylic acid component, wherein the dihydric phenol component is at least one selected from the group consisting of bis(4-hydroxyphenyl)ether, 4,4-[1,3-phenylenebis(1-methylethylidene)]bisphenol, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxyphenyl)ethane and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, wherein a compound represented by general formula (C) is used at a molecular end of the polyarylate, and wherein a Q value (the amount of molten resin flowing out from a nozzle hole having a diameter of 1 mm and a length of 10 mm using Koka flow tester (high-load-type flow tester) at a temperature of 280 C. under a pressure of 15.69 MPa) of the polyarylate is 110.sup.2 cm.sup.3/sec or more: ##STR00022## wherein in the formula, Y represents a hydroxyl group or an acid chloride, n is an integer of 1 to 3, and X is ##STR00023## wherein each R.sub.5 represents a branched or unbranched alkyl group having 5 to 20 carbon atoms, and wherein the compound represented by general formula (C) is at least one selected from the group consisting of ortho-t-amylphenol, para-nonylphenol, para-dodecylphenol, 2,4-di-t-amylphenol, and 2-ethylhexyl-4-hydroxybenzoate.

2. The molded article according to claim 1, wherein the polystyrene equivalent weight-average molecular weight of the polyarylate measured by gel permeation chromatography is 20000 or more and less than 80000.

3. The molded article according to claim 1, wherein the dihydric phenol component is at least one selected from the group consisting of bis(4-hydroxyphenyl)ether, 4,4-[1,3-phenylenebis(1-methyl ethylidene)]bisphenol, and 2,2-bis(4-hydroxyphenyl)-4-methylpentane.

4. The molded article according to claim 1, wherein the dihydric phenol component is at least one selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, and 1,1-bis(4-hydroxyphenyl)ethane, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

5. The molded article according to claim 1, wherein the dihydric phenol component is bis(4-hydroxyphenyl)ether.

6. The molded article according to claim 1, wherein the dihydric phenol component is 2,2-bis(4-hydroxyphenyl)-4-methylpentane.

7. The molded article according to claim 1, wherein the dihydric phenol component is 2,2-bis(4-hydroxyphenyl)propane.

8. The molded article according to claim 1, wherein the dihydric phenol component is 2,2-bis(4-hydroxy-3-methylphenyl)propane.

9. The molded article according to claim 1, wherein the dihydric phenol component is 1,1-bis(4-hydroxyphenyl)ethane.

10. The molded article according to claim 1, wherein the dihydric phenol component is 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

11. The molded article according to claim 1, wherein the compound represented by general formula (C) is ortho-t-amylphenol.

12. The molded article according to claim 1, wherein the compound represented by general formula (C) is para-nonylphenol.

13. The molded article according to claim 1, wherein the compound represented by general formula (C) is para-dodecylphenol.

14. The molded article according to claim 1, wherein the compound represented by general formula (C) is 2,4-di-t-amylphenol.

15. The molded article according to claim 1, wherein the compound represented by general formula (C) is 2-ethylhexyl 4-hydroxybenzoate.

16. A molded article obtained by injection molding or extrusion molding a polyarylate obtained from a dihydric phenol component and an aromatic dicarboxylic acid component, wherein the dihydric phenol component is 2,2-bis(4-hydroxyphenyl)propane, wherein a compound represented by general formula (C) is used at a molecular end of the polyarylate, and wherein a Q value (the amount of molten resin flowing out from a nozzle hole having a diameter of 1 mm and a length of 10 mm using Koka flow tester (high-load-type flow tester) at a temperature of 280 C. under a pressure of 15.69 MPa) is 110.sup.2 cm.sup.3/sec or more: ##STR00024## wherein in the formula, Y represents a hydroxyl group or an acid chloride, n is an integer of 1 to 3, and X is ##STR00025## wherein each R.sub.5 represents a branched or unbranched alkyl group having 5 to 20 carbon atoms, and wherein the compound represented by general formula (C) is para-dodecylphenol.

Description

EXAMPLES

(1) Hereinafter, the content of the invention will be described in detail by way of working examples of the first embodiment of the present invention together with comparative examples, but the first embodiment of the present invention is not limited to these working examples.

(2) <GPC Conditions>

(3) The measurement was carried out under the following conditions:

(4) Alliance HPLC system manufactured by Waters;

(5) 2 columns of Shodex805L manufactured by Showa Denko K.K.;

(6) a sample of 0.25 w/v % chloroform solution; chloroform eluent of 1 ml/min; and

(7) UV detection at 254 nm.

(8) The polystyrene equivalent weight-average molecular weight (Mw) and number-average molecular weight (Mn) were obtained.

(9) <Pencil Hardness Test>

(10) The hardness of the polyarylate film of the present invention formed on a glass substrate was measured by the pencil hardness test based on JIS K5600-5-4.

Example A1

(11) 0.5 g of hydro sulfite and 318 g (1 mol) of 1,1-bis(4-hydroxy-3-methylphenyl)-1-phenylethane represented by the structural formula below (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as OCAP) were dissolved in 2.3 L of 5 w/w % aqueous solution of sodium hydroxide, 2.1 g of tri-n-butylbenzyl ammonium chloride as a polymerization catalyst was added thereto, and in addition, 2.7 L of methylene chloride solution in which 205 g of a mixture of terephthalic acid chloride and isophthalic acid chloride (1:1) (manufactured by Tokyo Chemical Industry Co., Ltd.) and 6 g of p-tert-butylphenol (manufactured by DIC Corporation, hereinafter abbreviated as PTBP) were dissolved was added thereto, and the mixture was subjected to an interfacial polycondensation reaction at about 20 C. for 2 hours. After the reaction was completed, the reaction solution was separated into an aqueous phase and an organic phase. The organic phase was neutralized with phosphoric acid and washed with water repeatedly until the conductivity of the wash liquid (aqueous phase) became 10 S/cm or less. The obtained polymer solution was added dropwise to hot water with its temperature being maintained at 60 C. and the solvent was removed by evaporation, thereby obtaining a powdery white precipitate. The obtained precipitate was filtered and dried at 105 C. for 24 hours, thereby obtaining a polymer powder.

(12) ##STR00011##

(13) The molecular weight of this polymer obtained by the GPC measurement was as follows: Mw=57700; and Mn=18100. The obtained polymer was analyzed by infrared spectroscopy. As a result, absorption by a carbonyl group or ester group at a position near 1750 cm.sup.1 and absorption by an ester bond at a position near 1220 cm.sup.1 were recognized, and it was confirmed that it was a polyarylate having an ester bond.

(14) The obtained polyarylate was dissolved in methylene chloride in an amount of 15% by mass, and a cast film was prepared on a glass substrate using a doctor blade. After drying, a film having a thickness of 20 m was obtained. The obtained film was subjected to the pencil hardness test.

Example A2

(15) The process was carried out in a manner similar to that in Example A1, except that 296 g of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane represented by the structural formula below (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as OCZ) was used instead of OCAP, thereby obtaining a polyarylate with Mw=71400 and Mn=18100. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

(16) ##STR00012##

Example A3

(17) The process was carried out in a manner similar to that in Example A1, except that 352 g of 1,1-bis(4-hydroxyphenyl)cyclododecane represented by the structural formula below (manufactured by Taoka Chemical Company, Limited, hereinafter abbreviated as CD) was used instead of OCAP, thereby obtaining a polyarylate with Mw=64000 and Mn=19400. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

(18) ##STR00013##

Example A4

(19) The process was carried out in a manner similar to that in Example A1, except that the amount of OCAP was changed to 190.8 g and 76 g of 1,1-bis(4-hydroxy-3-methylphenyl)cyclododecane represented by the structural formula below (manufactured by Taoka Chemical Company, Limited, hereinafter abbreviated as OCCD) and 45.6 g of bisphenol A (manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as BPA) were used additionally, thereby obtaining a polyarylate with Mw=63100 and Mn=19900. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

(20) ##STR00014##

Example A5

(21) The process was carried out in a manner similar to that in Example A1, except that 281.6 g of CD and 51.2 g of 2,2-bis(4-hydroxy-3-methylphenyl)propane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as BPC) were used instead of OCAP, thereby obtaining a polyarylate with Mw=64700 and Mn=20000. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

Example A6

(22) The process was carried out in a manner similar to that in Example A1, except that the amount of OCAP was changed to 222.6 g and 80.4 g of 1,1-bis(4-hydroxyphenyl)cyclohexane (manufactured by Taoka Chemical Company, Limited, hereinafter abbreviated as BPZ) was used additionally, thereby obtaining a polyarylate with Mw=57000 and Mn=17800. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

Example A7

(23) 5.92 kg (20 mol) of OCZ was dissolved in 45 L of 5 w/w % aqueous solution of sodium hydroxide, 42 g of tri-n-butylbenzyl ammonium chloride as a polymerization catalyst was added thereto, and in addition, 55 L of methylene chloride solution in which 4.1 kg of a mixture of terephthalic acid chloride and isophthalic acid chloride (1:1) (manufactured by Tokyo Chemical Industry Co., Ltd.) and 240 g of PTBP were dissolved was added thereto, and the mixture was subjected to an interfacial polycondensation reaction at about 20 C. for 2 hours. Neutralization, purification, solidification and drying were carried out in a manner similar to that in Example A1, thereby obtaining a polyarylate with Mw=37800 and Mn=9770.

(24) This polyarylate was introduced into a 30 mm single screw extruder with a vent (MK-30 manufactured by Musashino Kikai Co., Ltd.) at a cylinder temperature of 320 C., passed through a feed-block type T-die, and subjected to heat removal using a horizontal twin roll (roll temperature: 150 C.), thereby obtaining an extruded film (thickness: about 110 m). The obtained film was put on a glass plate and subjected to the pencil hardness test in a manner similar to that in Example A1.

Comparative Example A1

(25) The process was carried out in a manner similar to that in Example A1, except that 228 g of BPA was used instead of OCAP, thereby obtaining a polyarylate with Mw=78300 and Mn=24400. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

Comparative Example A2

(26) The process was carried out in a manner similar to that in Example A1, except that 268 g of BPZ was used instead of OCAP, thereby obtaining a polyarylate with Mw=57700 and Mn=11200. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

Comparative Example A3

(27) The process was carried out in a manner similar to that in Example A1, except that 290 g of 1,1-bis(4-hydroxyphenyl)-1-phenylethane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as BPAP) was used instead of OCAP, thereby obtaining a polyarylate with Mw=48600 and Mn=15300. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

Comparative Example A4

(28) The process was carried out in a manner similar to that in Example A1, except that 256 g of BPC was used instead of OCAP, thereby obtaining a polyarylate with Mw=66800 and Mn=17400. The obtained polyarylate was molded in a manner similar to that in Example A1, and it was subjected to the pencil hardness measurement.

(29) The results of Examples A1 to A7 and Comparative Examples A1 to A4 are shown in Table 1.

(30) TABLE-US-00001 TABLE 1 (A) dihydric phenol (B) dihydric phenol Other dihydric phenols Weight-average Pencil Type mol % Type mol % Type mol % molecular weight (Mw) Hardness Example A1 OCAP 100 57700 2H Example A2 OCZ 100 71400 2H Example A3 CD 100 64000 3H Example A4 OCAP 60 OCCD 20 BPA 20 63100 2H Example A5 CD 80 BPC 20 64700 3H Example A6 OCAP 70 BPZ 30 57000 2H Example A7 OCZ 100 37800 2H Comparative BPA 100 78300 B Example A1 Comparative BPZ 100 57700 F Example A2 Comparative BPAP 100 48600 HB Example A3 Comparative BPC 100 66800 F Example A4

(31) Hereinafter, the content of the invention will be described in detail by way of working examples of the second embodiment of the present invention together with comparative examples, but the second embodiment of the present invention is not limited to these working examples.

(32) <GPC Conditions>

(33) The measurement was carried out under the following conditions:

(34) Alliance HPLC system manufactured by Waters;

(35) 2 columns of Shodex805L manufactured by Showa Denko K.K.;

(36) a sample of 0.25 w/v % chloroform solution; chloroform eluent of 1 ml/min; and

(37) UV detection at 254 nm.

(38) The polystyrene equivalent weight-average molecular weight (Mw) and number-average molecular weight (Mn) were obtained.

(39) <Flowability (Q Value) Measurement Conditions>

(40) The amount of molten resin flowing out from a nozzle hole (orifice) having a diameter of 1 mm and a length of 10 mm (unit: 10.sup.2 cm.sup.3/sec) was measured using an elevated flow tester (CFT-500D manufactured by Shimadzu Corporation) at a temperature of 280 C. under a pressure of 15.69 MPa.

(41) <Evaluation of Injection Molding>

(42) A tensile dumbbell specimen of JIS7 having a thickness of 1 mm was injection-molded using a small injection molding machine (C. Mobile manufactured by Shinko Sellbic Co., Ltd.) under the following conditions: injection pressure: 283 MPa, injection velocity: 20 mm/sec, resin temperature of polyarylate: 320 C., and mold temperature: 100 C. When it was impossible to carry out molding at a resin temperature of 320 C., the resin temperature was set at 360 C. and the mold temperature was set at 150 C.

(43) <Evaluation of Mold Contamination at the Time of Injection Molding>

(44) Injection molding of 500 shots was carried out under the aforementioned conditions for the evaluation of injection molding, and after that, the surface of the mold was wiped by a waste cloth and the presence or absence of an attached matter was confirmed. The case where no attached matter was confirmed was evaluated as , and the case where an attached matter was confirmed was evaluated as .

Example B1

(45) 0.5 g of hydrosulfite and 228 g (1 mol) of bisphenol A (manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as BPA) were dissolved in 2.3 L of 5 w/w % aqueous solution of sodium hydroxide, 2.1 g of tri-n-butylbenzyl ammonium chloride as a polymerization catalyst was added thereto, and in addition, 2.7 L of methylene chloride solution in which 205 g of a mixture of terephthalic acid chloride and isophthalic acid chloride (1:1) (manufactured by Tokyo Chemical Industry Co., Ltd.) and 21.0 g of para-dodecylphenol represented by the structural formula below (manufactured by Petrochemical Schenectady Co., Ltd., hereinafter abbreviated as PDP) were dissolved was added thereto, and the mixture was subjected to an interfacial polycondensation reaction at about 20 C. for 2 hours. After the reaction was completed, the reaction solution was separated into an aqueous phase and an organic phase. The organic phase was neutralized with phosphoric acid and washed with water repeatedly until the conductivity of the wash liquid (aqueous phase) became 10 S/cm or less. The obtained polymer solution was added dropwise to hot water with its temperature being maintained at 60 C. and the solvent was removed by evaporation, thereby obtaining a powdery white precipitate. The obtained precipitate was filtered and dried at 105 C. for 24 hours, thereby obtaining a polymer powder.

(46) ##STR00015##

(47) The molecular weight of this polymer obtained by the GPC measurement was as follows: Mw=38300; and Mn=8940. The obtained polymer was analyzed by infrared spectroscopy. As a result, absorption by a carbonyl group or ester group at a position near 1750 cm.sup.1 and absorption by an ester bond at a position near 1220 cm.sup.1 were recognized, and it was confirmed that it was a polyarylate having an ester bond.

(48) 0.03% by mass of stearic acid monoglyceride (manufactured by Kao Corporation) as a mold release agent and 0.03% by mass of cyclic neopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl)phosphite (ADEKA STAB PEP-36 manufactured by ADEKA Corporation) which is a phosphite-based antioxidant were added to and mixed with the obtained polyarylate. After that, the mixture was compressed at 300 C. and 9.8 MPa for 5 minutes to obtain a solid, it was coarsely crushed, and it was subjected to the measurement of the Q value and injection molding at 320 C.

Example B2

(49) The process was carried out in a manner similar to that in Example B1, except that 256 g of 2,2-bis(4-hydroxy-3-methylphenyl)propane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as BPC) was used instead of BPA and 13.1 g of ortho-t-amylphenol represented by the structural formula below (manufactured by Petrochemical Schenectady Co., Ltd., hereinafter abbreviated as OTAP) was used instead of PDP, thereby obtaining a polyarylate with Mw=33200 and Mn=8880. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1.

(50) ##STR00016##

Example B3

(51) The process was carried out in a manner similar to that in Example B1, except that 296 g of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as OCZ) was used instead of BPA and 18.7 g of 2,4-di-t-amylphenol represented by the structural formula below (manufactured by Petrochemical Schenectady Co., Ltd., hereinafter abbreviated as DTAP) was used instead of PDP, thereby obtaining a polyarylate with Mw=37600 and Mn=8960. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1.

(52) ##STR00017##

Example B4

(53) The process was carried out in a manner similar to that in Example B1, except that 214 g of 1,1-bis(4-hydroxyphenyl)ethane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as BPE) was used instead of BPA and 20.0 g of 2-ethylhexyl 4-hydroxybenzoate represented by the structural formula below (manufactured by Ueno Fine Chemicals Industry, Ltd., hereinafter abbreviated as POEH) was used instead of PDP, thereby obtaining a polyarylate with Mw=38900 and Mn=10600. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1.

(54) ##STR00018##

Example B5

(55) The process was carried out in a manner similar to that in Example B1, except that 270 g of 2,2-bis(4-hydroxyphenyl)-4-methylpentane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as MIBK) was used instead of BPA and 17.6 g of para-nonylphenol represented by the structural formula below (manufactured by Petrochemical Schenectady Co., Ltd., hereinafter abbreviated as PNP) was used instead of PDP, thereby obtaining a polyarylate with Mw=36200 and Mn=9920. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1.

(56) ##STR00019##

Example B6

(57) The process was carried out in a manner similar to that in Example B1, except that 101 g of bis(4-hydroxyphenyl)ether (manufactured by DIC Corporation, hereinafter abbreviated as DHPE) and 173 g of 4,4-[1,3-phenylenebis(1-methylethylidene)]bisphenol (manufactured by Mitsui Fine Chemicals, Inc., hereinafter abbreviated as BPM) were used instead of BPA and 13.7 g of para-t-octylphenol represented by the structural formula below (manufactured by DIC Corporation, hereinafter abbreviated as PTOP) was used instead of PDP, thereby obtaining a polyarylate with Mw=45900 and Mn=12000. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1.

(58) ##STR00020##

Comparative Example B1

(59) The process was carried out in a manner similar to that in Example B1, except that 12 g of p-tert-butylphenol represented by the structural formula below (manufactured by DIC Corporation, hereinafter abbreviated as PTBP) was used instead of PDP, thereby obtaining a polyarylate with Mw=39600 and Mn=12300. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1, but since it was impossible to carry out injection molding at 320 C., injection molding was carried out at 360 C.

(60) ##STR00021##

Comparative Example B2

(61) The process was carried out in a manner similar to that in Example B4, except that 12 g of PTBP was used instead of POEH, thereby obtaining a polyarylate with Mw=39400 and Mn=11100. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1, but since it was impossible to carry out injection molding at 320 C., injection molding was carried out at 360 C.

Comparative Example B3

(62) The process was carried out in a manner similar to that in Example B1, except that 2.7 g of p-tert-butylphenol (manufactured by DIC Corporation, hereinafter abbreviated as PTBP) was used instead of PDP, thereby obtaining a polyarylate with Mw=114000 and Mn=22700. The obtained polyarylate was subjected to the evaluation of molding in a manner similar to that in Example B1. However, in the Q value measurement, almost no resin flowed, and there was almost no slope of the amount of flow relative to time, and therefore, it was evaluated as not detected (ND). In addition, since it was impossible to carry out injection molding at 320 C., injection molding was carried out at 360 C. However, even at 360 C., it did not lead to filling of resin into a mold and it was impossible to carry out injection molding of 500 shots.

(63) The results of Examples B1 to B6 and Comparative Examples B1 to B3 are shown in Table 2.

(64) TABLE-US-00002 TABLE 2 Compound Polymer- Weight-aver- Mold contamina- of for- ization age molec- Injection tion at the Dihydric phenols mula (C) degree set ular weight Q value molding time of injec- Type mol % Type mol % Type (n) (Mw) (10.sup.2 cm.sup.3/sec) at 320 C. tion molding Example B1 BPA 100 PDP 25 38300 2.0 Possible Example B2 BPC 100 OTAP 25 33200 4.0 Possible Example B3 OCZ 100 DTAP 25 37600 3.4 Possible Example B4 BPE 100 POEH 25 38900 2.5 Possible Example B5 MIBK 100 PNP 25 36200 5.6 Possible Example B6 DHPE 50 BPM 50 PTOP 30 45900 4.4 Possible Comparative BPA 100 PTBP 25 39600 0.2 Impossible x Example B1 Comparative BPE 100 PTBP 25 39400 0.4 Impossible x Example B2 Comparative BPA 100 PTBP 110 114000 ND Impossible Impossible Example B3

INDUSTRIAL APPLICABILITY

(65) Regarding application examples of the present invention, for example, it is possible to provide front plates of flat panel displays and touch panel displays for portable devices which require scratch resistance. The polyarylate of the present invention can be injection-molded at a temperature lower than conventional polyarylates, and this realizes energy saving. Further, mold contamination caused by a mold release agent or additive is reduced, and this contributes to ease of maintenance. Moreover, the present invention can be applied to various injection-molded articles, regarding which high flowability is desired at the time of heating and melting, in particular, light-guiding plates of flat panel displays, various optical lenses, lighting covers, etc.