ANTISTATIC AGENT, ANTISTATIC RESIN COMPOSITION, AND MOLDED ARTICLE

Abstract

An object of the present invention is to provide an antistatic agent which imparts excellent antistatic properties to thermoplastic resins. The antistatic agent (Z) of the present invention contains a block polymer (A) having a block of a polyamide (a) and a block of a polyether (b1) as structure units, wherein the polyether (b1) contains propylene oxide (PO) and ethylene oxide (EO) as constituent monomers, and a weight ratio of the propylene oxide (PO) to the ethylene oxide (EO), i.e., propylene oxide (PO)/ethylene oxide (EO), is 1/99 to 25/75.

Claims

1. An antistatic agent (Z) comprising a block polymer (A) having a block of a polyamide (a) and a block of a polyether (1) as structure units, wherein the polyether (b 1) comprises propylene oxide (PO) and ethylene oxide (EO) as constituent monomers, and a weight ratio of the propylene oxide (PO) to the ethylene oxide (EO), i.e., propylene oxide (PO)/ethylene oxide (EO), is 1/99 to 25/75.

2. The antistatic agent (Z) according to claim 1, wherein the polyether (b 1) has a number average molecular weight (Mn) of 1,000 to 3,500.

3. The antistatic agent (Z) according to claim 1, wherein the polyamide (a) has a number average molecular weight (Mn) of 200 to 5,000.

4. The antistatic agent (Z) according to claim 1, wherein the block polymer (A) has a number average molecular weight (Mn) of 5,000 to 100,000.

5. The antistatic agent (Z) according to claim 1, further comprising an amide-forming monomer (c), wherein a weight of the amide-forming monomer (c) based on a weight of the block polymer (A) is 2 to 12 wt %.

6. The antistatic agent (Z) according to claim 5, wherein the amide-forming monomer (c) is a C6-C12 lactam.

7. The antistatic agent (Z) according to claim 1, further comprising an imidazolium salt (S).

8. An antistatic resin composition (Y) comprising: the antistatic agent (Z) according to claim 1; and a thermoplastic resin (E).

9. The antistatic resin composition (Y) according to claim 8, wherein a weight ratio of the antistatic agent (Z) to the thermoplastic resin (E), i.e., antistatic agent (Z)/thermoplastic resin (E), is 3/97 to 20/80.

10. A molded article obtained by molding the antistatic resin composition (Y) according to claim 8.

Description

EXAMPLES

[0119] The present invention is described below with reference to the examples and comparative examples, but the present invention is not limited thereto. Parts in the examples represent weight parts, unless otherwise specified.

Production Example 1

Production of Polyamide (a-1)

[0120] A stainless-steel pressure-resistant reaction vessel equipped with a stirrer, a thermometer, a heating and cooling device, a nitrogen inlet tube, and a decompression device was charged with ε-caprolactam (79.4 parts), terephthalic acid (11.5 parts), an antioxidant (“Irganox 1010” available from BASF Japan Ltd.) (0.3 parts), and water (6 parts). After purging with nitrogen, the mixture was hermetically heated to 220° C. with stirring, and stirred at the same temperature (pressure: 0.2 to 0.3 MPa) for four hours, thus obtaining a polyamide (a-1) having a carboxy group at each end.

[0121] The polyamide (a-1) had an acid value of 78 and a Mn of 1,400.

Production Example 2

Production of Polyamide (a-2)

[0122] A pressure-resistant reaction vessel similar to the one used in Production Example 1 was charged with co-laurolactam (82.5 parts), terephthalic acid (16.3 parts), an antioxidant (“Irganox 1010” available from BASF Japan Ltd.) (0.3 parts), and water (10 parts). After purging with nitrogen, the mixture was hermetically heated to 220° C. with stirring, and stirred at the same temperature (pressure: 0.2 to 0.3 MPa) for four hours, thus obtaining a polyamide (a-2) having a carboxy group at each end.

[0123] The polyamide (a-2) had an acid value of 109 and a Mn of 1,000.

Production Example 3

Production of Polyamide (a-3)

[0124] A pressure-resistant reaction vessel similar to the one used in Production Example 1 was charged with hexamethylenediamine (17.7 parts), adipic acid (37.1 parts), an antioxidant (“Irganox 1010” available from BASF Japan Ltd.) (0.3 parts), and water (160 parts). After purging with nitrogen, the mixture was hermetically heated to 270° C. with stirring, and stirred at the same temperature (pressure: 1.7 to 1.8 MPa) for four hours, thus obtaining a polyamide (a-3) having a carboxy group at each end.

[0125] The polyamide (a-3) had an acid value of 132 and a Mn of 850.

Production Example 4

Block Polymer (A-1)

[0126] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the polyamide (a-1) (209.9 parts), the polyether (b1-1) (291.8 parts), and zirconium oxyacetate (7 parts). The mixture was heated to 240° C. with stirring, and reacted under reduced pressure (0.013 MPa or less) at the same temperature for six hours, thus obtaining a block polymer (A-1).

[0127] The block polymer (A-1) had a Mn of 22,000 and a weight ratio ((a)/(b1)) of 42/58. The results are shown in Table 1.

Production Examples 5 to 9 and Comparative Production Examples 1 and 2

[0128] Block polymers (A-2) to (A-6) and (Comparative A-1) and (Comparative A-2) were obtained as in Production Example 4, except for following the formulation for reaction (by parts) shown in Table 1. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Comparative Production Production Example Example 4 5 6 7 8 9 1 2 Block polymer (A) A-1 A-2 A-3 A-4 A-5 A-6 Comparative Comparative A-1 A-2 Formulation Polyamide a-1 209.9 230.2 166 230.2 — 171.4 209.9 132.2 for (a) a-2 — — — — 186.4 — — — reaction/parts a-3 — — — — — 42.9 — — Polyether b1-1 291.8 — — — — — — — (b1) b1-2 — 272.1 — — 316.8 288.3 — — b1-3 — — 334.6 — — — — — b1-4 — — — 272.1 — — — — Comparative — — — — — — 291.8 — Example b1-1 Comparative — — — — — — — 367.6 Example b1-2 Properties of Mn 22,000 22,000 26,000 49,000 16,000 30,00 27,000 22,000 block polymer (A) Weight ratio 42/58 46/54 33/67 46/54 37/63 43/57 42/58 27/73 [(a)/(b1)] Polyether (b1) (b1-1): PO/EO random copolymer, weight ratio ((PO)/(EO)) = 3/97, Mn: 2000 (b1-2): PO/EO random copolymer, weight ratio ((PO)/(EO)) = 10/90, Mn: 1700 (b1-3): PO/EO random copolymer, weight ratio ((PO)/(EO)) = 14/86, Mn: 2900 (b1-4): PO/EO random adduct of bisphenol A, weight ratio ((PO)/(EO)) = 5/95, Mn: 1700 (Comparative Example b1-1): polyethylene glycol (PEG), weight ratio ((PO)/(EO)) = 0/100, Mn: 2000 (Comparative Example b1-2): PO/EO random copolymer, weight ratio ((PO/EO)) = 30/70, Mn: 4000

Example 1

[0129] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the block polymer (A-1) (100 parts) and an imidazolium salt (S-2) (2 parts). After mixing and stirring at 220° C. for one hour, the mixture was taken out in the form of a strand onto a belt and pelletized, thus obtaining an antistatic agent (Z-1).

Example 2

[0130] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the block polymer (A-1) (100 parts) and ε-caprolactam (c-1) (5 parts). After mixing and stirring at 220° C. for one hour, the mixture was taken out in the form of a strand onto a belt and pelletized, thus obtaining an antistatic agent (Z-2).

Examples 3 to 11 and Comparative Examples 1 and 2

[0131] In each of the examples and the comparative examples, the antistatic agents (Z-3) to (Z-11) and (Comparative Example Z-1) and (Comparative Example Z-2) were obtained as in Example 1 or 2, except for following the formulation (by parts) shown in Table 2.

TABLE-US-00002 TABLE 2 Example Comparative Example 1 2 3 4 5 6 7 8 9 10 11 1 2 Antistatic agent (Z) Z-1 Z-2 Z-3 Z-4 Z-5 Z-6 Z-7 Z-8 Z-9 Z-10 Z-11 Comparative Comparative Example Z-1 Example Z-2 Formulation/ Block A-1 100 100 — — — — — — — — — — — parts polymer (A) A-2 — — 100 100 100 100 — — — — — — — A-3 — — — — — — 100 — — — — — — A-4 — — — — — — — 100 — — — — — A-5 — — — — — — — — 100 100 — — — A-6 — — — — — — — — — — 100 — — Comparative — — — — — — — — — — — 100 — A-1 Comparative — — — — — — — — — — — — 100 A-2 Amide-forming c-1 —  5 —  5 — — — — —  8  5 — — monomer (c) c-2 — — — —  2 — — —  9 — — — — Imidazolium S-1 — — — —  6  4 — — — — — — — salt (S) S-2  2 — — — — — — — —  4 — — — Amide-forming monomer (c) (c-1): ε-caprolactam (c-2): ω-laurolactam Imidazolium salt (S) (S-1): 1-ethyl-3-methylimidazolium dodecylbenzenesulfonate (S-2): 1-ethyl-3-methylimidazolium ethyl sulfate

Examples 12 to 25 and Comparative Examples 3 and 4

[0132] In each of the examples and the comparative examples, the antistatic agent (Z) and the thermoplastic resin (E) were blended following the formulation shown in Table 3 with a Henschel mixer for three minutes. Then, the mixture was melt-kneaded in a twin-screw extruder with a vent at 90 rpm with a retention time of two minutes at 260° C., thus obtaining antistatic resin compositions (Y-1) to (Y-14) and (Comparative Example Y-1) and (Comparative Example Y-2).

[0133] Each of the resulting antistatic resin compositions (Y-1) to (Y-14) and (Comparative Example Y-1) and (Comparative Example Y-2) was evaluated according to <Evaluation method> described later. Table 3 shows the results.

Thermoplastic Resin (E)

[0134] (E-1): ABS resin (product name “Cevian-V320” available from Daicel Polymer Ltd.) [0135] (E-2): high impact PS resin (product name “HIPS 433” available from PS Japan Co., Ltd.) [0136] (E-3): Polycarbonate resin (product name: Panlite L-1225L available from Teijin Chemicals Ltd.)

Evaluation Methods

[0137] 1. Surface Specific Resistance (unit: Ω)

[0138] From each resin composition, a flat plate test piece (length 100 mm, width 100 mm, thickness 2 mm) was produced using an injection molding machine (product name “PS40E5ASE” available from Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260° C. and a mold temperature of 80° C. Each flat plate test piece was measured using an ultra megohmmeter “DSM-8103” (available from DKK-TOA CORPORATION) under an atmospheric environment at 23° C. with a humidity of 40% RH.

2. Izod Impact Strength (unit: J/m) (Evaluation of Mechanical Strength)

[0139] From each resin composition, a test piece (length 63.5 mm, width 12.7 mm, thickness 3.2 mm) was produced using an injection molding machine (product name “PS40E5ASE” available from Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260° C. and a mold temperature of 80° C. Each test piece was measured according to ASTM D256 Method A (with a notch, 3.2 mm thick).

3. Continuous Moldability (Demoldability)

[0140] From each resin composition, a flat plate test piece (length 70 mm, width 70 mm, thickness 2 mm) was produced using an injection molding machine (product name “PS40E5ASE” available from Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260° C., a mold temperature of 80° C., and a molding cycle of 30 seconds. After 1,000 shots of injection molding, the demoldability was evaluated according to <Evaluation criteria> described below.

[0141] The demoldability was evaluated based on the following formula (1):

Demoldability (%)=(D1000)×100/(D1)  (1)

where (D1) is the resisting force (unit: N) required for demolding at the first shot, and (D1000) is the resisting force required for demolding at the 1000th shot.

Evaluation Criteria

[0142] ⊚: less than 110% [0143] ○: 110% or more and less than 120% [0144] Δ: 120% or more and less than 130% [0145] x: 130% or more

TABLE-US-00003 TABLE 3 Example 12 13 14 15 16 17 18 19 Antistatic resin composition (Y) Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 Y-7 Y-8 Formulation Antistatic Type Z-1 Z-2 Z-3 Z-4 Z-5 Z-6 Z-7 Z-8 agent (Z) (Parts) 10 10 10 10 10 10 10 10 Thermoplastic Type E- 1 E-1 E-1 E-1 E-1 E-1 E-1 E-1 resin (E) (Parts) 90 90 90 90 90 90 90 90 Evaluation Surface specific 1.4 × 10.sup.11 2.1 × 10.sup.11 3.0 × 10.sup.11 1.1 × 10.sup.11 4.6 × 10.sup.10 1.5 × 10.sup.11 2.5 × 10.sup.11 2.1 × 10.sup.11 results resistance (Ω) Impact strength (J/m) 142 158 145 160 155 142 138 142 Continuous moldability ○ ⊚ ○ ⊚ ⊚ ○ ○ ○ (demoldability) Example Comparative Example 20 21 22 23 24 25 3 4 Antistatic resin composition (Y) Y-9 Y-10 Y-11 Y-12 Y-13 Y-14 Comparative Comparative Example Y-1 Example Y-2 Formulation Antistatic Type Z-9 Z-10 Z-10 Z-11 Z-5 Z-5 Comparative Comparative agent (Z) Example Z-1 Example Z-2 (Parts) 10 5 12 10 10 10 10 10 Thermoplastic Type E-1 E-1 E-1 E-1 E-2 E-3 E-1 E-1 resin (E) (Parts) 90 95 88 90 90 90 90 90 Evaluation Surface specific 5.7 × 10.sup.10 8.8 × 10.sup.10 1.9 × 10.sup.10 1.3 × 10.sup.11 4.0 × 10.sup.10 5.4 × 10.sup.10 7.8 × 10.sup.11 2.6 × 10.sup.12 results resistance (Ω) Impact strength (J/m) 155 158 145 150 62 540 130 95 Continuous moldability ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ × ○ (demoldability)

[0146] The results in Table 3 demonstrate that the antistatic resin compositions (Y) (Examples 12 to 25) containing the antistatic agents (Z) (Examples 1 to 11) of the present invention provide molded articles having lower surface specific resistance and better antistatic properties, provide molded articles having better mechanical strength (mechanical properties), and have better continuous moldability (demoldability) during molding as compared with the antistatic resin compositions (Comparative Examples 3 and 4) containing the antistatic agents (Comparative Examples 1 and 2).

INDUSTRIAL APPLICABILITY

[0147] The antistatic agent (Z) of the present invention imparts excellent antistatic properties to thermoplastic resins. The molded article has excellent mechanical strength and excellent continuous moldability (demoldability) during molding.

[0148] Thus, the antistatic resin composition is widely usable as a material of housing products (home appliances, office automation (OA) machines, gaming machines, and office appliances), plastic container materials (trays for cleanrooms (e.g., IC trays), and other containers), various buffer materials, covering materials (e.g., packaging films and protective films), sheets of flooring material, artificial grass, mats, substrates of a tape (for a semiconductor fabrication process or the like), and various molded articles (e.g., automobile parts), which are molded by various molding methods (injection molding, compression molding, calendaring molding, slush molding, rotational molding, extrusion molding, blow molding, foam molding, and film molding (e.g., casting method, tenter method, and inflation method)). Thus, the antistatic resin composition is very useful.