ADDITIVE COMPOSITION, RESIN COMPOSITION CONTAINING SAME, AND MOLDED ARTICLE OF SAID RESIN COMPOSITION

Abstract

Provided are an additive composition capable of improving the mechanical characteristics and color tone of a cellulose nanofiber-containing resin composition, a resin composition, and a molded article of the resin composition. The additive composition includes (A) a cellulose nanofiber and (D) a nucleating agent.

Claims

1. An additive composition comprising: (A) a cellulose nanofiber; and (D) a nucleating agent.

2. The additive composition according to claim 1, wherein (D) the nucleating agent comprises an aromatic phosphate metal salt represented by the following general formula (1): ##STR00005## where R.sup.1 to R.sup.5 independently represent a hydrogen atom or a linear or branched C.sub.1-6 alkyl group; n represents 1 or 2; when n is 1, M.sup.1 represents an alkali metal or dihydroxyaluminum; and, when n is 2, M.sup.1 represents an alkaline earth metal, zinc, or hydroxyaluminum.

3. The additive composition according to claim 1, further comprising (B) an alcohol compound.

4. The additive composition according to claim 1, further comprising (C) an antioxidant.

5. The additive composition according to claim 4, wherein (C) the antioxidant comprises at least one selected from the group consisting of phenol antioxidants and phosphorus antioxidants.

6. A resin composition comprising: (A) a cellulose nanofiber; (D) a nucleating agent; and (E) a synthetic resin.

7. A molded article obtained by molding the resin composition according to claim 6.

8. The additive composition according to claim 2, further comprising (B) an alcohol compound.

9. The additive composition according to claim 2, further comprising (C) an antioxidant.

10. The additive composition according to claim 3, further comprising (C) an antioxidant.

Description

EXAMPLES

[0105] The present invention will now be described more specifically with reference to Examples. The present invention should not be limited by the following Examples in any way.

[0106] <Preparation of Resin Composition>

Examples 1 to 4 and Comparative Examples 1 to 2

[0107] As listed in Table 1, (A) the cellulose nanofiber, (B) the alcohol compound, (C) the antioxidant, (D) the nucleating agent, and (E) the synthetic resin were supplied in the respective blending amounts listed in Table 1, and together with these components, 0.05 parts by mass of fatty acid metal salt (calcium stearate) was supplied. The components supplied were mixed uniformly. The resulting mixture was supplied into a twin-screw extruder (Labo Plastomill Micro, manufactured by Toyo Seiki Seisaku-sho, Ltd.), melt-kneaded under conditions at a melting temperature of 230° C. and at a screw speed of 50 rpm, and then granulated to give pellets. The resulting pellets were dried at 80° C. for 6 hours, and then used as resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2. In Table 1, the unit of the blending amount of each component is part(s) by mass.

[0108] The components used as the raw materials for the resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2 are as below-mentioned.

[0109] [(A) Cellulose Nanofiber]

[0110] (A-1) cellulose nanofiber in polypropylene masterbatch (CNF-mixed PP masterbatch, manufactured by GS Alliance Co., Ltd.) containing 40 mass % cellulose nanofiber

[0111] [(D) Nucleating Agent]

[0112] (D-1) sodium 2,2′-methylenebis(4,6-di-tert-butylphenyl)phosphate

[0113] [(B) Alcohol Compound]

[0114] (B-1) dipentaerythritol

[0115] (B-2) pentaerythritol

[0116] (B-3) tris(2-hydroxyethyl)isocyanurate

[0117] [(C) Antioxidant]

[0118] (C-1) tetrakis[methylene-3-(3′,5′-tert-butyl-4′-hydroxyphenyl)propionate]methane

[0119] (C-2) tris(2,4-di-tert-butylphenyl)phosphite

[0120] [(E) Synthetic Resin]

[0121] (E-1) homopolypropylene (the melt flow rate of which is 8 g/10 min at 230° C. and at a load of 2.16 kg)

[0122] (E-2) polypropylene in polypropylene masterbatch (CNF-mixed PP masterbatch, manufactured by GS Alliance Co., Ltd.) containing 40 mass % cellulose nanofiber

[0123] <Characteristics Evaluation>

[0124] (Mechanical Characteristics)

[0125] The flexural moduli of the resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2 were measured and regarded as the indexes for the mechanical characteristics. Specifically, the resin composition pellets in Examples 1 to 4 and Comparative Examples 1 to 2 were dried at 80° C. for 8 hours, and then injection-molded using an injection molding machine (EC-220, manufactured by Toshiba Machine Co., Ltd.) under conditions at a resin temperature of 230° C. and a mold temperature of 40° C. to produce bending test pieces, 80 mm×10 mm×4 mm each. These test pieces were left to stand at a temperature of 23° C. and a humidity of 50% in a thermohygrostat for 48 hours, and then taken out of the thermohygrostat. The flexural modulus (MPa) of the test piece was measured using a bending tester (AG-IS, manufactured by Shimadzu Corporation) in accordance with ISO178. The results are listed in Table 1.

[0126] (Color Tone)

[0127] The color differences E*.sub.ab of the resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2 were measured and regarded as the indexes for the color tone. Specifically, the pellets of the resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2 were used to measure the colors of the resin compositions by a reflection method using a spectrocolorimeter (Spectrophotometer SD3000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS Z8722:2009. From the measurement results obtained, the color difference ΔE*.sub.ab from a standard white plate (L*=99.76, a*=−0.05, and b*=0.27) was calculated in accordance with JIS Z 8730:2009, and regarded as the index for the color tone of the resin composition. The results are listed in Table 1.

[0128] (Crystallization Temperature)

[0129] The crystallization temperatures of the resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2 were measured by differential thermal analysis. Specifically, a measurement was made as follows: the pellets of the resin compositions were supplied into a differential scanning calorimeter (DIAMOND, manufactured by Perkin Elmer Co., Ltd.), heated under a nitrogen atmosphere from room temperature to 230° C. at a rate of 50° C./min, held for 20 minutes, and then cooled to 50° C. at −10° C./min. The peak top temperature of the exothermic peak in the cooling process was regarded as the crystallization temperature (° C.). The results are listed in Table 1.

[0130] (Heat Resistance)

[0131] The pellets of each of the resin compositions in Examples 1 to 4 and Comparative Examples 1 to 2 were sandwiched between two glass plates, and hot-pressed at a temperature of 230° C. to produce a film having a thickness of 0.2 mm. The film thus obtained was heated at 150° C. in a gear oven for 18 hours in a heat resistance test. The yellowness index (YI) of the film before and after the heat resistance test was measured by a reflection method using a spectrocolorimeter (Spectrophotometer SD3000, manufactured by Nippon Denshoku Industries Co., Ltd.). Then, a difference ΔYI between the YI after the heat resistance test and the YI before the heat resistance test was calculated, and regarded as the index for the heat resistance of the resin composition. The results are listed in Table 1.

TABLE-US-00001 TABLE 1 Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 (E) Synthetic Resin (E-1) 85 85 85 85 85 100 (E-2) 15 15 15 15 15 — (A) Cellulose Nanofiber (A-1) 10 10 10 10 10 — (D) Nucleating Agent (D-1) 0.1 0.1 0.1 0.1 — 0.1 (B) Alcohol Compound (B-1) — 1 — — — — (B-2) — — 0.8 — — — (B-3) — — — 1.7 — — (C) Antioxidant (C-1) 0.1 0.1 0.1 0.1 0.1 0.1 (C-2) 0.1 0.1 0.1 0.1 0.1 0.1 Flexural Modulus (MPa) 2100 2150 2130 2110 2050 1970 Color Tone (ΔE*.sub.ab) 51.0 51.4 51.2 50.4 58.0 18.7 Crystallization Temperature (° C.) 128.0 128.3 128.5 129.5 122.7 129.4 Heat Resistance (ΔYI) 32.8 4.0 9.3 5.4 30.5 0.1

[0132] The results mentioned in Table 1 have revealed that the resin compositions in Examples 1 to 4 have excellent mechanical characteristics and color tone. On the other hand, the resin compositions in Comparative Examples 1 to 2 did not have sufficient mechanical characteristics or color tone.

[0133] The above-mentioned results have verified that the additive composition according to the present invention makes it possible to improve the mechanical characteristics and color tone of a cellulose nanofiber-containing resin composition.