Resin composition and molded article made from the resin composition

Abstract

To provide a cellulosic powder-containing resin composition excellent in rigidity and impact resistance, and a molded article formed from the composition.SOLUTION: A cellulosic powder-containing resin composition contains 1 wt.% or more and 99 wt.% or less of a hydroxyl group-containing resin (A), 1 wt.% or more and 99 wt.% or less of cellulosic powder (B), and 0.01 wt.% or more and 2 wt.% or less of an isocyanate-based crosslinking agent (C) (total of (A), (B) and (C) is 100 wt.%.).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition comprising a hydroxyl group-containing resin, a cellulose-based powder, and an isocyanate-based crosslinking agent, and more specifically to a resin composition characterized by excellent rigidity and impact resistance, and a molded article made from the composition. [Background technology]

[0002] With the growing interest in environmental conservation in recent years, attention has been focused on reducing the use of petroleum-derived resins. One way to reduce the amount of petroleum-derived resins used is to partially replace them with non-petroleum-derived materials, and not only non-petroleum-derived resins but also wood-based materials such as cellulose-based powders are being used. Composite resins with these cellulose-based powders is advantageous in terms of cost, recyclability, and disposability, and products whose main component is cellulose-based powder will no longer be treated as plastic waste, so its widespread use is desired for environmental reasons.

[0003] However, products made from these cellulose powder composite resins have poor mechanical properties, and it is difficult to obtain sufficient impact resistance, particularly strength sufficient to withstand use in various products.

[0004] Therefore, methods have been developed to improve the mechanical strength of cellulose powder composite resins, but these methods also have various problems.

[0005] Patent Document 1 discloses a composite material of polypropylene and recycled paper, but it uses a large amount of water to break the bonds between cellulose, and dehydration and drying also require a large amount of energy, which is problematic from an environmental perspective.

[0006] Patent Document 2 discloses a composite material of ethylene-vinyl acetate copolymer and recycled paper, but the chemical bond between them is weak, and the interfacial adhesion is low, resulting in insufficient strength.

[0007] Patent Document 3 discloses a composite material of polyethylene and wood flour, but the high mixing temperature causes problems such as deterioration of the wood flour, discoloration, and other deterioration in physical properties and poor appearance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 6-73231 [Patent Document 2] Patent Publication No. 2000-265002 [Patent Document 3] Special Publication 2007-523252 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a resin composition characterized by excellent rigidity and impact resistance, and a molded article made from the composition. [Means for solving the problem]

[0010] As a result of extensive research to solve the above problems, the present inventors have found that a resin composition containing a cellulose powder having a specific blend has excellent rigidity and impact resistance, and have thus completed the present invention.

[0011] That is, the present invention relates to a cellulose-based powder-containing resin composition containing 1% by weight or more and 99% by weight or less of a hydroxyl group-containing resin (A), 1% by weight or more and 99% by weight or less of a cellulose-based powder (B), and 0.01% by weight or more and 2% by weight or less of an isocyanate-based crosslinking agent (C) (where the total of (A), (B), and (C) is 100% by weight), and to a molded article using the cellulose-based powder-containing resin composition. [Effects of the Invention]

[0012] The resin composition of the present invention is excellent in impact resistance and elongation at break, and is useful for molded articles that require these physical properties. DETAILED DESCRIPTION OF THE INVENTION

[0013] The cellulose powder-containing resin composition according to one embodiment of the present invention will be described in detail below.

[0014] The present invention is a cellulose-based powder-containing resin composition (hereinafter referred to as "the resin composition of the present invention") that contains a hydroxyl group-containing resin (A), a cellulose-based powder (B), and an isocyanate-based crosslinking agent (C).

[0015] The resin composition of the present invention contains a hydroxyl group-containing resin (A).

[0016] The hydroxyl group-containing resin (A) is not particularly limited, but examples thereof include vinyl alcohol polymers such as polyvinyl alcohol, vinyl acetate-vinyl alcohol copolymer, ethylene-vinyl alcohol copolymer, and ethylene-vinyl acetate-vinyl alcohol copolymer, acrylic acid polymers having hydroxy groups such as hydroxyethyl acrylate, and glycerin polymers such as polyglycerin and partial esters of polyglycerin.

[0017] Among these, ethylene-vinyl acetate-vinyl alcohol copolymer is particularly preferred because it significantly improves rigidity and impact resistance when blended with cellulose powder (B) in the presence of an isocyanate crosslinking agent (C).

[0018] Ethylene-vinyl acetate-vinyl alcohol copolymers are obtained by hydrolyzing ethylene-vinyl acetate copolymers obtained by known manufacturing methods (also called "saponified ethylene-vinyl acetate copolymers"). Such resins can be conveniently selected from commercially available products. Saponified ethylene-vinyl acetate copolymers are commercially available from Tosoh Corporation under the trade name Mersen H.

[0019] The number of hydroxyl groups in the hydroxyl group-containing resin (A) is preferably 5 to 50. If the number is less or more than this range, the efficiency of the hydroxyl group-containing resin (A) bonding to the cellulose powder (B) via the isocyanate-based crosslinking agent (C) decreases.

[0020] The molecular weight of the hydroxyl group-containing resin (A) is preferably from 5,000 to 500,000 in terms of weight average molecular weight, so that it has sufficient rigidity for use in a molded article. The weight average molecular weight here refers to the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

[0021] The melt mass flow rate of the hydroxyl group-containing resin (A) is not particularly limited, but in order to achieve excellent molding processability, it is preferably 0.1 g / 10 min or more and 1000 g / 10 min or less, more preferably 0.5 g / 10 min or more and 100 g / 10 min or less, and even more preferably 1 g / 10 min or more and 30 g / 10 min or less.

[0022] The cellulose-based powder (B) of the present invention is not particularly limited, but examples thereof include cellulose powder obtained by pulverizing cellulose, paper powder containing cellulose as the main component, wood flour, pulp, cellulose scum, sawdust, wood fiber, and rice husk, and may be those bound with hemicellulose or lignin.

[0023] From the viewpoint of dispersibility in the hydroxyl group-containing resin (A), the particle size of the cellulose powder (B) is preferably 10 to 200 μm, more preferably 100 μm or less, and most preferably 50 μm or less.

[0024] It is preferable that the moisture content of the cellulose powder (B) is 10% or less, since this improves the bonding strength with the hydroxyl group-containing resin (A) via the isocyanate-based crosslinking agent (C), and it is more preferably 5% or less, and most preferably 3% or less.

[0025] The isocyanate-based crosslinking agent (C) of the present invention has two or more isocyanate groups, and examples thereof include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, or adducts thereof. Among these, aliphatic adducts are preferred from the viewpoint of safety. Commercially available aliphatic adducts include Coronate 2612, an adduct of hexamethylene diisocyanate manufactured by Tosoh Corporation. By melt-kneading the hydroxyl-containing resin (A), the cellulose-based powder (B), and the isocyanate-based crosslinking agent (C), the hydroxyl groups of the hydroxyl-containing resin (A) and the hydroxyl groups of the cellulose-based powder (B) form urethane bonds via the isocyanate-based crosslinking agent (C), thereby producing a crosslinked product of the hydroxyl-containing resin (A) and the cellulose-based powder (B).

[0026] The resin composition of the present invention preferably contains 1 to 99% by weight of the hydroxyl-containing resin (A), 1 to 99% by weight of the cellulose-based powder (B), and 0.01 to 2% by weight of the isocyanate-based crosslinking agent (C), based on a total of 100% by weight of the hydroxyl-containing resin (A), 1 to 99% by weight of the cellulose-based powder (B), and 0.01 to 2% by weight of the isocyanate-based crosslinking agent (C). From an environmental perspective, the resin composition preferably contains 1 to 80% by weight of the hydroxyl-containing resin (A), 20 to 99% by weight of the cellulose-based powder (B), and 0.05 to 2% by weight of the isocyanate-based crosslinking agent (C). The most preferred composition contains 1 to 50% by weight of the hydroxyl-containing resin (A), 50 to 99% by weight of the cellulose-based powder (B), and 0.1 to 1% by weight of the isocyanate-based crosslinking agent (C). By including 50% by weight or more of the cellulose-based powder (B), the product made from the resin composition of the present invention will not be regarded as plastic waste when discarded, which is desirable from the viewpoint of disposability.

[0027] The resin composition of the present invention can be kneaded by partially or simultaneously kneading the hydroxyl group-containing resin (A), the cellulose powder (B) and the isocyanate crosslinking agent (C) in a kneading machine.

[0028] Furthermore, the resin composition of the present invention may contain an antistatic agent, a light stabilizer, an ultraviolet absorber, a nucleating agent, a lubricant, an antioxidant, an antiblocking agent, a flow improver, a mold release agent, a flame retardant, a colorant, an inorganic neutralizing agent, a hydrochloric acid absorber, a filler conductive agent, a chain extender, a hydrolysis inhibitor, and the like, as long as the effects of the present invention are not impaired.

[0029] The method for obtaining the resin composition of the present invention is not particularly limited as long as the object of the present invention is achieved, and conventionally known extrusion kneading methods can be used. The kneading device is not particularly limited as long as it can uniformly disperse each component, and production can be performed using a commonly used resin kneading device. Examples of kneading devices include single-screw extruders, multi-screw extruders, Banbury mixers, pressure kneaders, rotating rolls, and internal mixers. The kneading temperature is preferably 80°C to 180°C, which is above the melting point of the hydroxyl group-containing resin (A), and more preferably 100 to 160°C. Kneading at 160°C or below can reduce thermal degradation and discoloration of the cellulose-based powder.

[0030] The molded article made of the cellulose powder-containing resin composition, which is one embodiment of the present invention, will be described in detail below.

[0031] The resin composition of the present invention can be used in various molding processes such as film molding, blow molding, foam molding, and extrusion molding.

[0032] The resin composition of the present invention can also be mixed with another polymer (D) as a masterbatch. Examples of the polymer (D) to be blended as a masterbatch include thermoplastic resins, specifically polyethylene, polypropylene, ethylene-vinyl acetate copolymers, and saponified products thereof.

[0033] In a resin composition containing polymer (D), it is preferable to contain 25% by weight or more and 50% by weight or less of cellulose powder (B) relative to 100% by weight of the total of (A), (B), (C), and (D) in the resin composition, since this allows for both mechanical strength and environmental friendliness to be achieved.

[0034] Molded articles made from the resin composition of the present invention can be suitably used as films, sheets, trays, foams, containers, artificial wood, etc. in the fields of daily necessities, civil engineering and construction, electronics and electrical equipment, automotive vehicle parts, packaging, etc. [Example]

[0035] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0036] (1) Melt mass flow rate (MFR) The MFR of the hydroxyl group-containing resin (A) was measured using a melt indexer (manufactured by Takara Kogyo Co., Ltd.) at 190°C under a load of 2.16 kg.

[0037] (2) Vinyl acetate content The vinyl acetate content was measured in accordance with JIS K6924-1.

[0038] (3) Impact strength The press-molded sheet having a thickness of 0.1 mm was measured using a puncture impact tester (FT-M type, manufactured by Toyo Seiki Seisakusho) under the condition of a test capacity of 3 J.

[0039] (4) Tensile test The press-molded sheet, 0.1 mm thick, was punched into ASTM D-1822-L dumbbell-shaped test pieces and measured using a Tensilon tensile tester (Orientec, RTE-1210) with a chuck distance of 30 mm and a tensile speed of 200 mm / min. The point at which the sample broke was taken as the breaking elongation (breaking elongation [%] = tensile length required to break [mm] / chuck distance 30 mm). The upper yield stress during the tensile test was used as an index of rigidity.

[0040] Example 1 The hydroxyl group-containing resin (A) was 49.9 wt % ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) with a vinyl acetate content of 7.9 mol %, a vinyl alcohol content of 3.4 mol %, and a melt mass flow rate of 5 g / 10 min; the cellulose-based powder (B) was 50 wt % cellulose powder (manufactured by Nippon Paper Industries Co., Ltd., trade name KC Flock W-100GK) with an average particle size of 37 μm; and the isocyanate-based crosslinking agent (C) was 0.1 wt % hexamethylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name Coronate 2612). The mixture was melt-kneaded at 140°C using an internal mixer.

[0041] The resulting kneaded material was press-molded using a press molding machine (AWFA-50 manufactured by Shinto Metal Industries) under conditions of a heating temperature of 160°C (primary pressure x 3 minutes, secondary pressure x 3 minutes) and a cooling temperature of 25°C (4 minutes) to obtain a pressed sheet with a thickness of 0.1 mm. Tensile tests and impact tests were performed using the obtained pressed sheet. The evaluation results are shown in Table 1.

[0042] Example 2 A press sheet was obtained in the same manner as in Example 1, except that the hydroxyl group-containing resin (A) was 49.7 wt% ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) with a vinyl acetate content of 7.9 mol%, a vinyl alcohol content of 3.4 mol%, and a melt mass flow rate of 5 g / 10 min, and the isocyanate-based crosslinking agent (C) was 0.3 wt% hexamethylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name Coronate 2612). Tensile tests and impact tests were performed using the obtained press sheet. The evaluation results are shown in Table 1.

[0043] Example 3 A press sheet was obtained in the same manner as in Example 1, except that the hydroxyl group-containing resin (A) was 79.9 wt% ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) having a vinyl acetate content of 7.9 mol%, a vinyl alcohol content of 3.4 mol%, and a melt mass flow rate of 5 g / 10 min, and the cellulose-based powder (B) was 20 wt% cellulose powder (manufactured by Nippon Paper Industries Co., Ltd., trade name KC Flock W-100GK) having an average particle size of 37 μm. Tensile tests and impact tests were performed using the obtained press sheet. The evaluation results are shown in Table 1.

[0044] Example 4 A press sheet was obtained in the same manner as in Example 1, except that the hydroxyl group-containing resin (A) was an ethylene-vinyl acetate-vinyl alcohol copolymer (79.7 wt %) having a vinyl acetate content of 7.9 mol %, a vinyl alcohol content of 3.4 mol %, and a melt mass flow rate of 5 g / 10 min (manufactured by Tosoh Corporation, trade name Mersen H-3051R), the cellulose powder (B) was a cellulose powder having an average particle size of 37 μm (manufactured by Nippon Paper Industries Co., Ltd., trade name KC Flock W-100GK) 20 wt %, and the isocyanate crosslinking agent (C) was an adduct of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name Coronate 2612). Tensile tests and impact tests were performed using the obtained press sheet. The evaluation results are shown in Table 1.

[0045] Comparative Example 1 A press sheet was obtained in the same manner as in Example 1, except that the hydroxyl group-containing resin (A) was 50% by weight of an ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) having a vinyl acetate content of 7.9 mol%, a vinyl alcohol content of 3.4 mol%, and a melt mass flow rate of 5 g / 10 min, and the cellulose-based powder (B) was 50% by weight of a cellulose powder (manufactured by Nippon Paper Industries Co., Ltd., trade name KC Flock W-100GK) having an average particle size of 37 μm. Tensile tests and impact tests were performed using the obtained press sheet. The evaluation results are shown in Table 1.

[0046] Comparative Example 2 The hydroxyl group-containing resin (A) was 45% by weight of an ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) with a vinyl acetate content of 7.9 mol%, a vinyl alcohol content of 3.4 mol%, and a melt mass flow rate of 5 g / 10 min, and the isocyanate-based crosslinking agent (C) was 5% by weight of an adduct of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name Coronate 2612). The mixture was kneaded in the same manner as in Example 1, but the mixture became rigid due to viscosity increase during kneading and was pulverized, making it impossible to process into a sheet.

[0047] Comparative Example 3 A press sheet was obtained in the same manner as in Example 1, except that the hydroxyl group-containing resin (A) was 80% by weight of an ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) having a vinyl acetate content of 7.9 mol%, a vinyl alcohol content of 3.4 mol%, and a melt mass flow rate of 5 g / 10 min, and the cellulose-based powder (B) was 20% by weight of a cellulose powder (manufactured by Nippon Paper Industries Co., Ltd., trade name KC Flock W-100GK) having an average particle size of 37 μm. Tensile tests and impact tests were performed using the obtained press sheet. The evaluation results are shown in Table 1.

[0048] Comparative Example 4 The hydroxyl group-containing resin (A) was 75% by weight of an ethylene-vinyl acetate-vinyl alcohol copolymer (manufactured by Tosoh Corporation, trade name Mersen H-3051R) having a vinyl acetate content of 7.9 mol%, a vinyl alcohol content of 3.4 mol%, and a melt mass flow rate of 5 g / 10 min. The cellulose-based powder (B) was 20% by weight of a cellulose powder (manufactured by Nippon Paper Industries Co., Ltd., trade name KC Flock W-100GK) having an average particle size of 37 μm. The isocyanate-based crosslinking agent (C) was 5% by weight of an adduct of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name Coronate 2612). The mixture was kneaded in the same manner as in Example 1, but the mixture became rigid due to viscosity increase during kneading and was pulverized, making it impossible to process into a sheet.

[0049] [Table 1] [Industrial Applicability]

[0050] Molded articles made from the resin composition of the present invention have excellent rigidity and impact resistance, and are therefore suitable for use as films, sheets, trays, foams, containers, artificial wood, etc. in the fields of daily necessities, civil engineering and construction, electronics and electrical machinery, automotive vehicle components, packaging, etc.

Claims

1. A cellulose-based powder-containing resin composition comprising 1% by weight or more and 98.99% by weight or less of a hydroxyl group-containing resin (A), 1% by weight or more and 98.99% by weight or less of a cellulose-based powder (B), and 0.01% by weight or more and 2% by weight or less of an isocyanate-based crosslinking agent (C) (wherein the total of (A), (B), and (C) is 100% by weight).

2. 2. The cellulose powder-containing resin composition according to claim 1, wherein the hydroxyl group-containing resin (A) is a saponified product of an ethylene-vinyl acetate copolymer.

3. 3. The cellulose-based powder-containing resin composition according to claim 1, wherein the cellulose-based powder (B) has an average particle size of 10 to 200 μm.

4. A cellulose-based powder-containing resin composition according to any one of claims 1 to 3, characterized in that the cellulose-based powder (B) is at least one selected from the group consisting of paper powder, wood powder, pulp, wood chips, sawdust, wood fiber, and rice husks.

5. 5. The cellulose powder-containing resin composition according to claim 1, wherein the isocyanate crosslinking agent (C) is at least one of hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and adducts thereof.

6. 6. The cellulose powder-containing resin composition according to claim 1, wherein the isocyanate crosslinking agent (C) is an adduct of hexamethylene diisocyanate.

7. A molded article obtained by molding the cellulose powder-containing resin composition according to any one of claims 1 to 6.

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