Polyacetal resin composition and resin molded article

Abstract

Provided is a polyacetal resin composition in which at least one dihydrazone compound (B) selected from the group of two kinds of dihydrazone compounds is blended in 0.02 to 5 parts by mass with respect to 100 parts by mass of a polyacetal resin (A).

Claims

1. A polyacetal resin composition in which at least one dihydrazone compound (B) selected from the group selected from a dihydrazone compound (B1) represented by the following General Formula (1) and a dihydrazone compound (B2) represented by the following General Formula (2) is blended in 0.02 to 5 parts by mass with respect to 100 parts by mass of a polyacetal resin (A) ##STR00009## in the above formula, R.sup.1 represents an aliphatic hydrocarbon group having 4 to 19 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms; R.sup.2 to R.sup.5 each represent an alkyl group having 1 or 2 carbon atoms ##STR00010## in the above formula, R.sup.8 represents an aliphatic hydrocarbon group having 4 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms; and R.sup.6 and R.sup.7 each independently represent an alicyclic hydrocarbon group having 3 to 12 carbon atoms.

2. The polyacetal resin composition according to claim 1, wherein, in the above General Formula (1), R.sup.1 is an aliphatic hydrocarbon group having 6 to 12 carbon atoms.

3. The polyacetal resin composition according to claim 1, wherein the dihydrazone compound (B) consists of the dihydrazone compound (B1) represented by the above General Formula (1).

4. The polyacetal resin composition according to claim 1, wherein the dihydrazone compound (B) consists of the dihydrazone compound (B2) represented by the above General Formula (2).

5. The polyacetal resin composition according to claim 1, wherein, in the above General Formula (1), R.sup.2 to R.sup.5 are each a methyl group.

6. The polyacetal resin composition according to claim 1, wherein the dihydrazone compound (B) is blended in 0.05 to 3 parts by mass with respect to 100 parts by mass of the polyacetal resin (A).

7. The polyacetal resin composition according to claim 1, wherein a hydrazide compound (C) is further blended at a ratio of 0.01 to 1 part by mass with respect to 100 parts by mass of the polyacetal resin (A).

8. The polyacetal resin composition according to claim 7, wherein the hydrazide compound (C) is composed of at least one kind of the group consisting of a monohydrazide compound and a dihydrazide compound.

9. The polyacetal resin composition according to claim 8, wherein the hydrazide compound (C) is composed of a dihydrazide compound.

10. A resin molded article being obtained by molding the polyacetal resin composition according to claim 1.

11. A polyacetal resin composition in which at least one dihydrazone compound (B) selected from the group selected from a dihydrazone compound (B1) represented by the following General Formula (1) and a dihydrazone compound (B2) represented by the following General Formula (2) is blended in 0.02 to 5 parts by mass with respect to 100 parts by mass of a polyacetal resin (A) ##STR00011## in the above formula, R.sup.1 represents an alkylene group having 11 to 19 carbon atoms, or an alicyclic hydrocarbon group having 7 to 10 carbon atoms; R.sup.2 to R.sup.5 each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms; at least one of R.sup.2 and R.sup.3 represents an alkyl group having 1 or 2 carbon atoms; and at least one of R.sup.4 and R.sup.5 represents an alkyl group having 1 or 2 carbon atoms ##STR00012## in the above formula, R.sup.8 represents an aliphatic hydrocarbon group having 4 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms; and R.sup.6 and R.sup.7 each independently represent an alicyclic hydrocarbon group having 3 to 12 carbon atoms.

12. The polyacetal resin composition according to claim 11, wherein, in the above General Formula (1), R.sup.1 is an alkylene group having 11 to 12 carbon atoms.

13. The polyacetal resin composition according to claim 11, wherein the dihydrazone compound (B) consists of the dihydrazone compound (B1) represented by the above General Formula (1).

14. The polyacetal resin composition according to claim 11, wherein the dihydrazone compound (B) consists of the dihydrazone compound (B2) represented by the above General Formula (2).

15. The polyacetal resin composition according to claim 11, wherein, in the above General Formula (1), when R.sup.2 and R.sup.4 are an ethyl group, R.sup.3 and R.sup.5 are a hydrogen atom, or when R.sup.2 and R.sup.4 are a methyl group, R.sup.3 and R.sup.5 are a hydrogen atom or a methyl group.

16. The polyacetal resin composition according to claim 11, wherein the dihydrazone compound (B) is blended in 0.05 to 3 parts by mass with respect to 100 parts by mass of the polyacetal resin (A).

17. The polyacetal resin composition according to claim 11, wherein a hydrazide compound (C) is further blended at a ratio of 0.01 to 1 part by mass with respect to 100 parts by mass of the polyacetal resin (A).

18. The polyacetal resin composition according to claim 17, wherein the hydrazide compound (C) is composed of at least one kind of the group consisting of a monohydrazide compound and a dihydrazide compound.

19. The polyacetal resin composition according to claim 18, wherein the hydrazide compound (C) is composed of a dihydrazide compound.

20. A resin molded article being obtained by molding the polyacetal resin composition according to claim 11.

Description

EXAMPLES

(1) Hereinafter, the invention will be described more specifically by means of Examples and Comparative Examples. However, the invention is not limited to the following Examples.

(2) Materials used in Examples and Comparative Examples are as follows.

(3) (A) Polyacetal Resin (POM)

(4) Acetal copolymer obtainable by copolymerizing trioxane and 1,3-dioxolan such that the content of 1,3-dioxolan in POM becomes 4.2% by mass, in which a melt index (ASTM-D1238 standard: 190° C., 2.16 kg) is 10.5 g/10 min.

(5) (B) Dihydrazone Compound B-1: 1,12-bis[2-(1-methylethylidene)hydrazino]]-1,12-dodecanedione B-2: 1,12-bis[2-(1-methylpropylidene)hydrazino]-1,12-dodecanedione B-3: 1,12-bis[2-(1-ethylpropylidene)hydrazino]-1,12-dodecanedione B-4: 1,12-bis(2-cyclohexylidenehydrazino)-1,12-dodecanedione B-5: 1,12-bis(2-ethylidenehydrazino)-1,12-dodecanedione B-6: 1,12-bis(2-propylidenehydrazino)-1,12-dodecanedione B-7: 1,8-bis[2-(1-methylethylidene)hydrazino]-1,8-octanedione B-8: 1,6-bis[2-(1-methylethylidene)hydrazino]-1,6-hexanedione B-9: 1,6-bis[2-(1-methylpropylidene)hydrazino]-1,6-hexanedione B-10: 1,3-bis[2-(1-methylethylidene)hydrazinocarbonyl]benzene B-11: 1,18-bis[2-(1-methylethylidene)hydrazino]-1,18-octadecanedione B-12: 1,4-bis[2-(1-methylethylidene)hydrazino)-1,4-cyclohexanedione B-13: 1,12-bis(2-methylidenehydrazino)-1,12-dodecanedione B-14: 1,3-bis(2-methylidenehydrazinocarbonyl)benzene B-15: 1,12-bis[2-(1,3-dimethylbutylidene)hydrazino]-1,12-dodecanedione B-16: 1,12-bis[2-(diphenylmethylidene)hydrazino]-1,12-dodecanedione B-17: 1,12-bis(2-benzylidenehydrazine)-1,12-dodecanedione B-18: 1,12-bis(2-neopentylidenehydrazino)-1,12-dodecanedione B-19: 1,6-bis[2-(1,3-dimethylbutylidene)hydrazino]-1,6-hexanedione B-20: 1,4-bis[2-(1-methylethylidene)hydrazino)-1,4-butanedione B-21: 1,22-bis[2-(1-methylethylidene)hydrazino)-1,22-docosanedione

(6) (C) Hydrazide Compound C-1: 1,12-dodecanedioic acid dihydrazide C-2: adipic acid dihydrazide C-3: isophthalic acid dihydrazide C-4: stearic acid hydrazide

(7) Incidentally, B-1 described above was synthesized as follows.

(8) A glass reaction vessel was charged with 310.0 g (1.2 mol) of dodecanedioic acid dihydrazide and 845.9 g of methanol and was heated to 50° C. Thereto, 348.5 g (6.0 mol) of acetone was added dropwise so as to perform reaction. Thereafter, the resultant mixture was cooled to precipitate crystals, and the crystals was separated by filtration, washed with water, and dried to thereby obtain 305.0 g of B-1 (weight yield: 75.1%).

(9) In addition, B-6 was obtained in the same manner as in B-1, except that propyl aldehyde was used as a raw material instead of acetone.

(10) B-2 to B-5 and B-7 to B-21 were obtained in the same manner as in B-1, except that acetone and dodecanedioic acid dihydrazide as raw materials were appropriately changed, respectively.

Production of Polyacetal Resin Composition

Examples 1 to 34 and Comparative Examples 1 to 11

(11) The polyacetal resin (A), the dihydrazone compound (B), and the hydrazide compound (C) were uniformly mixed at the blending ratios presented in Tables 1 to 10 with Super Mixer manufactured by KAWATA MFG Co., Ltd., and the obtained mixture was melted and kneaded with a biaxial extruder (PCM-30 manufactured by Ikegai Corp., screw diameter: 30 mm) according to the general method under the conditions of a screw rotation number of 120 rpm and a cylinder setting temperature of 190° C., extruded into a strand, and cut with a pelletizer to thereby produce a pellet of the polyacetal resin composition. Incidentally, in Tables 1 to 10, the unit of the blended amount is part(s) by mass.

(12) [Property Evaluation]

(13) (1) Effect of Suppressing Generation of Formaldehyde

(14) Regarding an effect of suppressing generation of formaldehyde, the generated amount of formaldehyde was measured and the evaluation was conducted on the basis of the generated amount of formaldehyde. The generated amount of formaldehyde was obtained as follows.

(15) <Preparation of Plate Test Piece>

(16) Pellets of the polyacetal resin compositions obtained in Examples 1 to 34 and Comparative Examples 1 to 11 were injection-molded by using an injection molding machine PS-40 manufactured by NISSEI PLASTIC INDUSTRIAL CO., LTD. at a cylinder temperature of 215° C. and a mold temperature of 80° C. to prepare plate test pieces of 100 mm×40 mm×2 mm.

(17) <Measurement of Generated Amount of Formaldehyde>

(18) On the day following the production of this plate test piece, for the plate test piece, the generated amount of formaldehyde (μg/g-POM) was measured by the following method according to the method described in German Automobile Industrial Association Standard VDA275 (Automobile Indoor Parts-Quantitative measurement of discharged amount of formaldehyde by revised flask method).

(19) (i) First, 50 ml of distilled water was put into a polyethylene vessel, the lid thereof was closed in a state in which the plate test piece was hung in the air, and the vessel was heated in a sealed state at 60° C. for 3 hours.

(20) (ii) Subsequently, after leaving the vessel at room temperature for 60 minutes, the plate test piece was taken out.

(21) (iii) The amount of formaldehyde absorbed into the distilled water in the polyethylene vessel was measured by acetylacetone colorimetry using a UV spectrometer, and a value obtained by dividing the amount of formaldehyde by the mass of POM in the plate test piece was used as the generated amount of formaldehyde. The results thereof are presented in Tables 1 to 10.

(22) Incidentally, in Tables 1 to 10, criteria of pass/fail on the effect of suppressing generation of formaldehyde were set as follows.

(23) A case where the generated amount of formaldehyde is 2.5 μg/g-POM or less: Pass

(24) A case where the generated amount of formaldehyde is more than 2.5 μg/g-POM: Fail

(25) (2) Effect of Suppressing Contamination of Mold

(26) The effect of suppressing contamination of the mold was evaluated as follows. First, using a Minimat M8/7A molding machine manufactured by Sumitomo Heavy Industries, Ltd. with a so-called droplet type mold, 3000-shot continuous molding was performed on the pellets of the polyacetal resin compositions obtained in Examples 1 to 34 and Comparative Examples 1 to 11 at a molding temperature of 200° C. and a mold temperature of 80° C. After the completion of molding, the state of inner wall surfaces of the mold was observed with the naked eyes. Herein, criteria on the effect of suppressing contamination of the mold were set as follows.

(27) A: There is no matter adhering to the mold and the effect of suppressing contamination of the mold is extremely good.

(28) B: There is a slightly small amount of matters adhering to the mold and the effect of suppressing contamination of the mold is extremely good.

(29) C: There is a small amount of matters adhering to the mold but the effect of suppressing contamination of the mold is good.

(30) D: There is a large amount of matters adhering to the mold and the effect of suppressing contamination of the mold is poor.

(31) Herein, A to C were considered to pass and D was considered to fail. The results thereof are presented in Tables 1 to 10.

(32) (3) Mechanical Property

(33) The mechanical property was evaluated as follows. First, using an injection molding machine (product name: EC100S, manufactured by TOSHIBA MACHINE CO., LTD.), temperatures of four cylinders disposed toward the downstream side from upstream side were set to 190° C., 190° C., 180° C., and 170° C., respectively, the mold temperature was set to 90° C., and the pellets of the polyacetal resin compositions obtained in Examples 1 to 34 and Comparative Examples 1 to 11 were injection-molded to thereby prepare test pieces for tensile test specified by ISO9988-2 standard. Then, using a tensile tester (product name: STROGRAPH APII, manufactured by Toyo Seiki Seisaku-sho, Ltd.), the tensile test was performed on the test pieces for tensile test under the condition according to 150527 standard and the tensile yield strength was measured. The results thereof are presented in Tables 1 to 10. In Tables 1 to 10, criteria of pass/fail on the mechanical property were as follows.

(34) A case where the tensile yield strength is 60 MPa or more: Pass

(35) A case where the tensile yield strength is less than 60 MPa: Fail

(36) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 (A) Polyacetal resin 100 100 100 100 100 (B) B-1 1,12-bis[2-(1- 0.02 0.05 0.1 0.3 0.5 Dihydrazone methylethylidene)hydrazino]- compound 1,12-dodecanedione Formaldehyde Generated amount of HCHO at 1.5 1 0.7 0.4 0.4 suppressing 215° C. (unit: μg/g-POM) effect Mold contamination property (MD) A A A A A Mechanical Tensile yield strength (MPa) 63 63 63 63 63 property

(37) TABLE-US-00002 TABLE 2 Example Example 6 Example 7 Example 8 Example 9 10 (A) Polyacetal resin 100 100 100 100 100 (B) B-1 1,12-bis[2-(1- 1 3 5 Dihydrazone methylethylidene)hydrazino]- compound 1,12-dodecanedione B-2 1,12-bis[2-(1- 0.3 methylpropylidene)hydrazino]- 1,12-dodecanedione B-3 1,12-bis[2-(1- 0.3 ethylpropylidene)hydrazino]- 1,12-dodecanedione Formaldehyde Generated amount of HCHO at 215° C. 0.4 0.4 0.4 1.8 2.1 suppressing (unit: μg/g-POM) effect Mold contamination property (MD) B B B A A Mechanical Tensile yield strength (MPa) 63 63 61 63 63 property

(38) TABLE-US-00003 TABLE 3 Example Example Example Example Example 11 12 13 14 15 (A) Polyacetal resin 100 100 100 100 100 (B) B-4 1,12-bis(2- 0.3 Dihydrazone cyclohexylidenehydrazino)- compound 1,12-dodecanedione B-5 1,12-bis(2- 0.3 ethylidenehydrazino)-1,12- dodecanedione B-6 1,12-bis(2- 0.3 propylidenehydrazino)-1,12- dodecanedione B-7 1,8-bis[2-(1- 0.3 methylethylidene)hydrazino]- 1,8-octanedione B-8 1,6-bis[2-(1- 0.3 methylethylidene)hydrazino]- 1,6-hexanedione Formaldehyde Generated amount of HCHO at 1.3 0.5 0.5 0.4 0.6 suppressing 215° C. (unit: μg/g-POM) effect Mold contamination property (MD) A A A A B Mechanical Tensile yield strength (MPa) 63 63 63 63 63 property

(39) TABLE-US-00004 TABLE 4 Example Example Example Example 16 17 18 19 (A) Polyacetal resin 100 100 100 100 (B) B-9 1,6-bis[2-(1-methylpropylidene)hydrazino]- 0.3 Dihydrazone 1,6-hexanedione compound B-10 1,3-bis[2-(1- 0.3 methylethylidene)hydrazinocarbonyl]benzene B-11 1,18-bis[2-(1-methylethylidene)hydrazino)- 0.3 1,18-octadecanedione B-12 1,4-bis[2-(1-methylethylidene)hydrazino)- 0.3 1,4-cyclohexanedione Formaldehyde Generated amount of HCHO at 0.7 0.4 2.3 0.3 suppressing 215° C. (unit: μg/g-POM) effect Mold contamination property (MD) B A A A Mechanical Tensile yield strength (MPa) 63 63 63 63 property

(40) TABLE-US-00005 TABLE 5 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 (A) Polyacetal resin 100 100 100 100 100 100 (B) B-1 1,12-bis[2-(1- 10 Dihydrazone methylethylidene)hydrazino]- compound 1,12-dodecanedione B-15 1,12-bis[2-(1,3- 0.3 dimethylbutylidene)hydrazino]- 1,12-dodecanedione B-16 1,12-bis[2- 0.3 (diphenylmethylidene)hydrazino]- 1,12-dodecanedione B-17 1,12-bis(2- 0.3 benzylidenehydrazino)-1,12- dodecanedione B-18 1,12-bis(2- 0.3 neopentylidenehydrazino)-1,12- dodecanedione Formaldehyde Generated amount of HCHO at 215° C. 8.1 0.4 4 5 3.7 2.9 suppressing (unit: μg/g-POM) effect Mold contamination property (MD) A B A A A A Mechanical Tensile yield strength (unit: MPa) 63 57 63 63 63 63 property

(41) TABLE-US-00006 TABLE 6 Comparative Comparative Comparative Comparative Comparative Example 7 Example 8 Example 9 Example 10 Example 11 (A) Polyacetal resin 100 100 100 100 100 (B) B-13 1,12-bis(2-methylidenehydrazino)- 0.3 Dihydrazone 1,12-dodecanedione compound B-14 1,3-bis(2- 0.3 methylidenehydrazinocarbonyl)benzene B-19 1,6-bis[2-(1,3- 0.3 dimethylbutylidene)hydrazino]-1,6- hexanedione B-20 1,4-bis[2-(1- 0.3 methylethylidene)hydrazino)-1,4- butanedione B-21 1,22-bis[2-(1- 0.3 methylethylidene)hydrazino)-1,22- docosanedione Formaldehyde Generated amount of HCHO at 215° C. (unit: 3 2.8 3.5 0.6 4.7 suppressing μg/g-POM) effect Mold contamination property (MD) B C C D A Mechanical Tensile yield strength (unit: MPa) 63 63 63 63 63 property

(42) TABLE-US-00007 TABLE 7 Example Example Example Example Example 20 21 22 23 24 (A) Polyacetal resin 100 100 100 100 100 (B) B-1 1,12-bis[2-(1- 0.1 0.1 0.1 0.1 0.1 Dihydrazone methylethylidene)hydrazino]- compound 1,12-dodecanedione (C) Hydrazide C-1 1,12-dodecanedioic acid 0.01 0.1 0.3 1 5 compound dihydrazide Formaldehyde Generated amount of HCHO at 0.5 0.4 0.3 0.3 0.2 suppressing 215° C. (unit: μg/g-POM) effect Mold contamination property (MD) A A B B C Mechanical Tensile yield strength (MPa) 63 63 63 63 61 property

(43) TABLE-US-00008 TABLE 8 Example Example Example 25 26 27 (A) Polyacetal resin 100 100 100 (B) Dihydrazone B-1 1,12-bis[2-(1- 0.1 0.1 0.1 compound methylethylidene)hydrazino]-1,12- dodecanedione (C) Hydrazide C-2 adipic acid dihydrazide 0.1 compound C-3 isophthalic acid dihydrazide 0.1 C-4 stearic acid hydrazide 0.1 Formaldehyde Generated amount of HCHO at 215° C. 0.5 0.5 0.6 suppressing effect (unit: μg/g-POM) Mold contamination property (MD) A A A Mechanical property Tensile yield strength (MPa) 63 63 63

(44) TABLE-US-00009 TABLE 9 Example Example Example Example 28 29 30 31 (A) Polyacetal resin 100 100 100 100 (B) Dihydrazone B-4 1,12-bis(2-cyclohexylidenehydrazino)-1,12- 0.1 compound dodecanedione B-5 1,12-bis(2-ethylidenehydrazino)-1,12- 0.1 dodecanedione B-8 1,6-bis[2-(1-methylethylidene)hydrazino]- 0.1 1,6-hexanedione B-10 1,3-bis[2-(1- 0.1 methylethylidene)hydrazinocarbonyl]benzene (C) Hydrazide C-1 1,12-dodecanedioic acid dihydrazide 0.1 0.1 0.1 0.1 compound Formaldehyde Generated amount of HCHO at 215° C. 1.4 0.6 0.6 0.5 suppressing (unit: μg/g-POM) effect Mold contamination property (MD) A A A A Mechanical Tensile yield strength (MPa) 63 63 63 63 property

(45) TABLE-US-00010 TABLE 10 Example Example Example 32 33 34 (A) Polyacetal resin 100 100 100 (B) Dihydrazone B-8 1,6-bis[2-(1- 0.1 0.1 0.1 compound methylethylidene)hydrazino]-1,6- hexanedione (C) Hydrazide C-2 adipic acid dihydrazide 0.01 0.5 1 compound Formaldehyde Generated amount of HCHO at 215° C. 0.6 0.4 0.3 suppressing effect (unit: μg/g-POM) Mold contamination property (MD) A B B Mechanical property Tensile yield strength (MPa) 63 63 63

(46) As presented in Tables 1 to 10, it was found that all of Examples 1 to 34 satisfied acceptance criteria in terms of formaldehyde generation suppression, mold contamination suppression, and mechanical property. In contrast, it was found that Comparative Examples 1 to 11 did not satisfy acceptance criteria in terms of formaldehyde generation suppression, mold contamination suppression, or mechanical property.

(47) Therefore, according to the polyacetal resin composition of the invention, it was confirmed that generation of formaldehyde can be sufficiently suppressed, contamination of the mold at the time of molding process can be sufficiently suppressed, and excellent mechanical property can be provided to a molded article.