ANTISTATIC AGENT, ANTISTATIC RESIN COMPOSITION, AND MOLDED PRODUCT

Abstract

An object of the present invention is to provide an antistatic agent which imparts excellent antistatic properties to thermoplastic resins. The antistatic agent of the present invention contains a block polymer (A) having a block of a polyamide (a) and a block of a hydrophilic polymer (b) as structure units; and an amide-forming monomer (c), wherein a weight ratio of the amide-forming monomer (c) to the block polymer (A), i.e., amide-forming monomer (c)/block polymer (A), is 2/98 to 12/88.

Claims

1. An antistatic agent (Z), comprising: a block polymer (A) having a block of a polyamide (a) and a block of a hydrophilic polymer (b) as structure units; and an amide-forming monomer (c), wherein a weight ratio of the amide-forming monomer (c) to the block polymer (A), i.e., amide-forming monomer (c)/block polymer (A), is 2/98 to 12/88.

2. The antistatic agent (Z) according to claim 1, wherein the hydrophilic polymer (b) is a polyether (b1).

3. The antistatic agent (Z) according to claim 1, wherein the amide-forming monomer (c) is a C6-C12 lactam.

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

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

6. The antistatic resin composition according to claim 5, 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.

7. A molded article obtained by molding the antistatic resin composition (Y) according to claim 5.

Description

EXAMPLES

[0121] 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

[0122] Production of Polyamide (a-1)

[0123] 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.

[0124] The polyamide (a-1) had an acid value of 78 and a Mn of 1,400.

Production Example 2

[0125] Production of Polyamide (a-2)

[0126] A pressure-resistant reaction vessel similar to the one used in Production Example 1 was charged with ω-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.

[0127] The polyamide (a-2) had an acid value of 109 and a Mn of 1,000.

Production Example 3

[0128] Production of Polyamide (a-3)

[0129] 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.

[0130] The polyamide (a-3) had an acid value of 132 and a Mn of 850.

Production Example 4

Block Polymer (A-1)

[0131] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the polyamide (a-1) (223 parts), an EO adduct (Mn: 1,800) (279 parts) of bisphenol A, and zirconium oxyacetate (7 parts). The mixture was heated to 240° C. with stirring, and polymerized under reduced pressure (0.013 MPa or less) at the same temperature for six hours, thus obtaining a block polymer (A-1).

[0132] The block polymer (A-1) had a Mn of 22,000 and a weight ratio (polyamide (a)/hydrophilic polymer (b)) of 44/56.

Production Example 5

Block Polymer (A-2)

[0133] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the polyamide (a-2) (253 parts), polyethylene glycol (Mn: 1,000) (253 parts), and zirconium oxyacetate (7 parts). The mixture was heated to 240° C. with stirring, and polymerized under reduced pressure (0.013 MPa or less) at the same temperature for six hours, thus obtaining a block polymer (A-2).

[0134] The block polymer (A-2) had a Mn of 50,000 and a weight ratio (polyamide (a)/hydrophilic polymer (b)) of 50/50.

Production Example 6

Block Polymer (A-3)

[0135] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the polyamide (a-1) (155.5 parts), the polyamide (a-3) (38.9 parts), polyethylene glycol (Mn: 2,000) (307.7 parts), and zirconium oxyacetate (7 parts). The mixture was heated to 240° C. with stirring, and polymerized under reduced pressure (0.013 MPa or less) at the same temperature for six hours, thus obtaining a block polymer (A-3).

[0136] The block polymer (A-3) had a Mn of 15,000 and a weight ratio (polyamide (a)/hydrophilic polymer (b)) of 39/61.

Example 1

[0137] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the block polymer (A-1) (98 parts) and e-caprolactam (c-1) (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).

Examples 2 to 6 and Comparative Examples 1 and 2

[0138] In each of the examples and the comparative examples, the antistatic agents (Z-2) to (Z-6) and (Comparative Example Z-1) and (Comparative Example Z-2) were obtained as in Example 1, except for following the formulation (by parts) shown in Table 1.

Example 7

[0139] A reaction vessel equipped with a stirrer, a thermometer, and a heating and cooling device was charged with the block polymer (A-1) (93 parts), ε-caprolactam (c-1) (7 parts), and an imidazolium salt (S-1) (4 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-7).

Example 8

[0140] The antistatic agent (Z-8) was obtained as in Example 7, except for following the formulation (by parts) shown in Table 1.

[0141] [Table 1]

TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 3 4 5 6 7 8 1 2 Antistatic agent (Z) Z-1 Z-2 Z-3 Z-4 Z-5 Z-6 Z-7 Z-8 Compar- Compar- ative Ex- ative Ex- ample Z-1 ample Z-2 Formula- Block A-1 98 95 89 95 — — 93 — 100 85 tion/parts polymer A-2 — — — — 95 — — 96 — — (A) A-3 — — — — — 95 — — — — Amide-forming c-1 2 5 11 — 5 5 7 — — 15 monomer (c) c-2 — — — 5 — — — 4 — — Imidazolium S-1 — — — — — — 4 — — — salt (S) S-2 — — — — — — — 2 — — Mn of block polymer (A) 22,000 22,000 22,000 22,000 50,000 15,000 22,000 50,000 22,000 22,000 Weight ratio [(c)/(A)] 2/98 5/95 11/89 5/95 5/95 5/95 7/93 4/96 — 15/85 (S)/[(A) + (c)] (wt %) 0 0 0 0 0 0 4 2 0 0 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 9 to 19 and Comparative Examples 3 and 4

[0142] 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 2 with a Henschel mixer for three minutes. Then, the mixture was melt-kneaded in a twin-screw extruder with a vent at 100 rpm with a retention time of three minutes at 260° C., thus obtaining antistatic resin compositions (Y-1) to (Y-11) and (Comparative Example Y-1) and (Comparative Example Y-2).

[0143] Each of the resulting antistatic resin compositions (Y-1) to (Y-11) and (Comparative Example Y-1) and (Comparative Example Y-2) was evaluated according to <Evaluation method> described later. Table 2 shows the results.

Thermoplastic Resin (E)

[0144] (E-1): ABS resin (product name “Cevian-V320” available from Daicel Polymer Ltd.)
(E-2): high impact PS resin (product name “HIPS 433” available from PS Japan Co., Ltd.)
(E-3): Polycarbonate resin (product name: Panlite L-1225L available from Teijin Chemicals Ltd.)

<Evaluation Method>

1. Cleanness of Molds

[0145] 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 cleanness of mold was evaluated according to <Evaluation criteria> described below.

<Evaluation Criteria>

[0146] Excellent: No change is observed on the mold surface.
Good: Slight uncleanness is observed on the mold surface.
Fair: Uncleanness is observed on the mold surface.
Poor: Extreme uncleanness is observed on the mold surface, and the appearance of the molded article is poor.

2. Demoldability

[0147] 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.

[0148] 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>

[0149] Excellent: less than 110%
Good: 110% or more and less than 120%
Fair: 120% or more and less than 130%
Poor: 130% or more

3. Surface Specific Resistance (Unit: 0)

[0150] 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.

4. Izod Impact Strength (unit: J/m)

[0151] 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).

TABLE-US-00002 TABLE 2 Example 9 10 11 12 13 14 15 16 Antistatic resin Y-4 Y-2 Y-3 Y-4 Y-5 Y-6 Y-7 Y-8 composition (Y) 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 5 Thermoplastic resin (E) Type E-1 E-1 E-1 E-1 E-1 E-1 E-1 E-1 (Parts) 90 90 90 90 90 90 90 95 Evaluation Cleanness of molds Excellent Excellent Good Excellent Excellent Excellent Excellent Excellent results Demoldability Good Excellent Excellent Excellent Excellent Excellent Excellent Good Surface specific resistance (Ω) 2.1 × 10.sup.11 1.6 × 10.sup.11 1.4 × 10.sup.11 1.3 × 10.sup.11 1.2 × 10.sup.11 1.1 × 10.sup.11 6.8 × 10.sup.10 8.1 × 10.sup.10 Impact strength (J/m) 150  160  155  160  160  160  165  160  Comparative Example Example 17 18 19 3 4 Antistatic resin Y-9 Y-10 Y-11 Comparative Comparative composition (Y) Example Y-1 Example Y-2 Formulation Antistatic Type Z-8 Z-2 Z-2 Comparative Comparative agent (Z) Example Z-1 Example Z-2 (Parts) 12 10 10 10 10 Thermoplastic resin (E) Type E-1 E-2 E-3 E-1 E-1 (Parts) 88 90 90 90 90 Evaluation Cleanness of molds Excellent Excellent Excellent Excellent Poor results Demoldability Excellent Excellent Excellent Fair Excellent Surface specific resistance (Ω) 4.7 × 10.sup.10 3.5 × 10.sup.11 4.6 × 10.sup.11 1.1 × 10.sup.12 5.9 × 10.sup.11 Impact strength (J/m) 150  65 550  145  130 

[0152] The results in Table 2 demonstrate that the antistatic resin compositions (Y) (Examples 9 to 19) containing the antistatic agents (Z) (Examples 1 to 8) 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 (cleanness of molds and 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

[0153] The antistatic agent (Z) of the present invention imparts excellent antistatic properties to thermoplastic resins. A molded article containing the antistatic agent (Z) of the present invention has excellent mechanical strength (mechanical properties) and excellent continuous moldability (cleanness of molds and demoldability) during molding. 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.