OIL-RESISTANT RESIN COMPOSITION, OIL-RESISTANT SHEET AND CONTAINER

Abstract

To provide an oil-resistant resin composition that can give a molding with high oil resistance.SOLUTION: An oil-resistant resin composition contains (A) a molded mixture of high impact polystyrene (HIPS) and crystallized polylactic acid, (B) a thermoplastic elastomer and (C) (C-1) amorphous polylactic acid or (C-2) different HIPS from HIPS contained in the component (A).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to an oil-resistant resin composition that can give a molded article having excellent oil resistance, an oil-resistant sheet obtained from the oil-resistant resin composition, and a container obtained from the oil-resistant sheet. [Background technology]

[0002] Good oil resistance is required for food containers that are used in contact with oil-containing foods such as prepared foods and sweets, and for storage containers for machine parts that come into contact with lubricating oils. Patent Document 1 discloses an invention relating to a resin composition containing 55 to 85 parts by mass of (A) a styrene-based resin and 15 to 45 parts by mass of (B) a polyester (preferably polylactic acid), and having a breaking time of 60 minutes or more as measured by a constant strain chemical resistance test method and a Vicat softening temperature of 70°C or more, and a molded article thereof (Claims). It is described that the resin composition and molded articles made from it have excellent chemical resistance (chemical resistance to oil; paragraph 0026) and heat resistance, making them advantageous for use in a wide range of fields, such as food containers and packaging, office automation equipment, electronic devices, and miscellaneous goods (paragraph 0060). The test specimens used in the constant strain chemical resistance test method in the examples were only those cut in the MD direction (paragraph 0049).

[0003] Patent Document 2 describes an invention (claims) for a laminated sheet in which a coating layer (B) composed of an olefin resin (B1) and a rubber-containing styrene resin (B3) is formed on at least one surface of a base layer (A) composed of an aliphatic polyester resin (A1) (preferably a polylactic acid resin) and a styrene thermoplastic elastomer (A2). Furthermore, the document states that "Since the laminated sheet of the present invention has excellent heat resistance and oil resistance, it is particularly suitable as a container (such as a container for prepared foods or other food containers) into which food is filled at high temperatures or which is heat-treated in an oven or microwave oven (paragraph 0091)."

[0004] Patent Document 3 describes an invention of a styrene-based stretched sheet obtained by biaxially stretching a styrene-based resin composition containing an impact-resistant styrene-based resin (A) and a polylactic acid (B), in which the mass ratio of the impact-resistant styrene-based resin (A) to the polylactic acid (B) used is in the range of 95 / 5 to 65 / 35, represented by (A) / (B), and the stretching ratio when the styrene-based resin composition is biaxially stretched is 1.3 to 8.0 times in at least one direction (claims). It further states that "the molded products obtained from the stretched sheet of the present invention have excellent oil resistance and can therefore be suitably used as food contents, even if they contain oil components (paragraph 0035)." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-48248 A [Patent Document 2] Patent No. 5069943 [Patent Document 3] Patent No. 6206701 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide an oil-resistant resin composition that can give a molded article having excellent oil resistance, an oil-resistant sheet obtained from the oil-resistant resin composition, and a container obtained from the oil-resistant sheet. [Means for solving the problem]

[0007] The present disclosure relates to (A) a molded product of a mixture of high impact polystyrene (HIPS) and crystallized polylactic acid (crystalline PLA); (B) a thermoplastic elastomer; and The present invention provides an oil-resistant resin composition containing (C-1) amorphous polylactic acid (amorphous PLA) or (C-2) a HIPS contained separately from the HIPS contained in component (A), an oil-resistant sheet obtained from the oil-resistant resin composition, and a food container obtained from the oil-resistant sheet. Effect of the Invention

[0008] The oil-resistant sheet obtained from the oil-resistant resin composition of the present invention has excellent oil resistance, and even an unstretched single-layer sheet maintains the oil resistance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 4 is a plan view illustrating an oil resistance test when the sheet is in a flat state. [Diagram 2] FIG. 13 is a side view for explaining an oil resistance test when the sheet is in a folded state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Oil-resistant resin composition> Component (A) is a molded mixture of HIPS and crystalline PLA. Component (A) can be obtained, for example, by heating and kneading HIPS and PLA (amorphous PLA) at the crystallization temperature of PLA (approximately 110°C ± 10°C), and then molding the mixture into a desired shape such as a known pellet. The melt flow rate (MFR) of the HIPS is preferably from 1 to 25 g / 10 min, and more preferably from 1.5 to 22 g / 10 min. Crystalline PLA includes amorphous PLA that has been partially crystallized, and is preferably derived from plants. The melt flow rate (MFR) of the crystalline PLA is preferably from 1 to 30 g / 10 min, and more preferably from 3.8 to 26.3 g / 10 min. The respective contents of the HIPS and the crystalline PLA in the total amount are preferably 50 to 85 parts by mass of HIPS and 15 to 50% by mass of polylactic acid, more preferably 60 to 75% by mass of HIPS and 25 to 40% by mass of polylactic acid. As the component (A), a product sold by Toyo Styrene Co., Ltd. under the trade name BM600 (containing 30% by mass of PLA) (crystallinity of 20% or 50%) can also be used.

[0011] Component (B) is a thermoplastic elastomer, and acts as a compatibilizer for the other components contained therein. Examples of the thermoplastic elastomer of the component (B) include urethane elastomers, polyester elastomers, olefin-based elastomers, polyamide elastomers, and styrene-based elastomers. Examples of component (B) include one or more selected from styrene-butadiene-styrene block polymers (SBS polymers), styrene-isoprene-styrene block polymers (SIS polymers), hydrogenated styrene-ethylene-butylene-styrene block polymers (SEBS polymers), hydrogenated styrene-ethylene-propylene-styrene block polymers (SEPS), ethylene-α-olefin polymers, ethylene-α-olefin-polyene polymers, silicone rubbers, acrylic rubbers, and butadiene-(meth)acrylic acid ester polymers. Among these, SBS polymer, SEBS polymer and SEPS polymer are more preferred, and SBS polymer is even more preferred.

[0012] The component (C) is HIPS contained in addition to the amorphous PLA of the component (C-1) or the HIPS contained in the component (A) of the component (C-2). The amorphous PLA of the component (C-1) is preferably plant-derived and has a melt flow rate (MFR) of preferably 1 to 30 g / 10 min, more preferably 3.8 to 26.3 g / 10 min. The HIPS of the component (C-2) preferably has a melt flow rate (MFR) of 1 to 25 g / 10 min, and more preferably 1.5 to 22 g / 10 min.

[0013] The content ratio of each component in the total amount of components (A) to (C) in the oil-resistant resin composition is, Preferably, the content is 50 to 90% by mass of the (A) component, 5 to 25% by mass of the (B) component, and 5 to 25% by mass of the (C) component. More preferably, the content is 60 to 90% by mass of the (A) component, 5 to 20% by mass of the (B) component, and 5 to 20% by mass of the (C) component. More preferably, the content is 70 to 90% by mass of the (A) component, 5 to 18% by mass of the (B) component, and 5 to 18% by mass of the (C) component.

[0014] The total content of the crystalline PLA and the amorphous PLA in the oil-resistant resin composition is preferably 20% by mass or more, more preferably 20 to 40% by mass, and even more preferably 25 to 35% by mass.

[0015] The oil-resistant resin composition may contain, within the scope of the invention, a stabilizer (antioxidants such as hindered phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants, light stabilizers such as ultraviolet absorbers, heat stabilizers, and the like), a flow improver, a plasticizer, a softener, a release agent, a flame retardant, an antistatic agent, a conductive agent, an antifogging agent, a colorant, a filler (particulate fillers such as silica, talc, and metal fillers, and fibrous fillers such as glass fibers, carbon fibers, and metal fibers, and the like), a crystal nucleus growth agent, a dispersant, a foaming agent, an antifoaming agent, an antibacterial agent, and the like.

[0016] <Oil-resistant sheets and containers> The oil-resistant sheet of the present disclosure is made from the above-mentioned oil-resistant resin composition. The thickness and size of the oil-resistant sheet can be selected depending on the application, and the thickness can be in the range of 0.1 to 0.8 mm, for example. The oil-resistant sheet can be produced by applying a known method such as extrusion molding or press molding.

[0017] The oil-resistant sheet of the present disclosure may be either a non-stretched sheet or a stretched sheet, but even if it is a non-stretched sheet, it has excellent oil resistance. Therefore, unlike the invention of Patent Document 3, there is no need to perform a stretching process to impart oil resistance, but it can be uniaxially or biaxially stretched to adjust the thickness according to the application. The oil-resistant sheet of the present disclosure may be a single-layer sheet or a laminated sheet, but even a single-layer sheet has excellent oil resistance. Therefore, it is not necessary to make a laminated sheet consisting of a base layer and a coating layer to impart oil resistance as in the invention of Patent Document 2. The oil-resistant sheet of the present disclosure can be obtained by adjusting the components of the oil-resistant resin composition to have excellent oil resistance in both the MD and TD, rather than only in the MD as in the invention of Patent Document 1. The oil-resistant sheet of the present disclosure is more preferably an unstretched single-layer sheet.

[0018] The container of the present disclosure is manufactured from the oil-resistant sheet described above, and the shape, thickness, size, etc. can be selected according to the application. The container of the present disclosure can be manufactured by using the oil-resistant sheet described above and applying conventional thermoforming such as pressure forming (extrusion pressure forming, hot plate pressure forming, vacuum pressure forming, etc.), free blow molding, vacuum forming, folding processing, matched mold forming, and hot plate forming. The containers disclosed herein can be used as food containers or parts thereof, such as containers for prepared foods, lunch boxes, and containers for oil-containing confectionery such as chocolate, cookies, and biscuits, liner sheets to be placed inside the food containers (e.g., at the bottom of the food container), and covering materials to cover food inside the food container. They can also be used in a wide range of fields, such as office equipment and its parts, electronic equipment and its parts, various machine parts, and miscellaneous goods.

[0019] Each feature disclosed herein may be combined with any other feature disclosed herein. Each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the gist of the disclosure of the present invention. The present disclosure is not limited by the embodiments, but is limited only by the claims. EXAMPLES

[0020] Component (A) HIPS / crystalline PLA: Product name: Toyo Enelights BM600 (containing 30% PLA by mass) (crystallinity 20%) (Toyo Styrene Co., Ltd.) (B) Component SBS polymer: styrene-based thermoplastic elastomer; trade name: Tufprene 126S (Asahi Kasei Corporation) (C-1) Component Amorphous PLA: Product name REVODE110 (Zhejiang Haizheng Biomaterial Co., Ltd.) (C-2) Component HIPS: Product name: Toyo Styrol HI E640 (Toyo Styrene Co., Ltd.)

[0021] Examples 1 to 3, Comparative Examples 1 to 4 The components shown in Table 1 were dry blended and then extruded under the following conditions to produce a sheet. (Extrusion conditions) Extruder: General-purpose horizontal extruder PG-65-32 type (Pla Giken Co., Ltd.) Cylinder temperature: 210℃ Roll temperature: 65℃ Sheet thickness: 0.4mm Sheet width: 700mm The obtained sheet was cut into test sheets measuring 150 mm in length and 10 mm in width, with the length directions being MD and TD, and the following oil resistance test was carried out. The results are shown in Table 1.

[0022] <Oil resistance test> (1) Oil resistance test 1 (test sheet is flat) As shown in Fig. 1, a test sheet 1 was placed on a flat table 20, and absorbent cotton 2 (10 mm square) soaked in MCT oil (medium chain fatty acid) was placed at the midpoint in the longitudinal direction. The absorbent cotton 2 used was soaked in a container containing MCT oil (medium chain fatty acid) for 60 seconds. After leaving the test sheet 1 at room temperature (20 to 25°C) for a predetermined time, the oil resistance was confirmed by checking whether it broke when the test sheet 1 was bent with fingers. The test was performed for 1 minute, 3 minutes, and 5 to 60 minutes. During the 5 to 60 minutes, the test sheet was taken out every 5 minutes to check whether it broke.

[0023] (2) Oil resistance test 2 (test sheet bent) The jig 10 shown in FIG. 2 was used. The jig 10 has a substrate 13 and two support plates 11, 12 vertically arranged at a distance W (W=36 mm or 24 mm) from the substrate portion 13. The substrate 13 is fixed onto a flat table 20. Two jigs with different W can be used as the jig 10, or one in which W can be adjusted by moving the two support plates 11, 12 can be used. As shown in FIG. 2, the test sheet 1 was sandwiched and held between two support plates 11 and 12 in a folded state so that the midpoint in the length direction became the apex. A piece of absorbent cotton 2 (10 mm square) soaked in MCT oil (medium chain fatty acid) was placed at the apex of the folded part of the test sheet 1 in the state shown in Figure 2. The absorbent cotton 2 used was soaked in a container containing MCT oil (medium chain fatty acid) for 60 seconds. After leaving the test sheet 1 at room temperature (20 to 25°C) for a predetermined time, the oil resistance was confirmed by checking whether it broke when the test sheet 1 was bent with fingers. The test was performed for 1 minute, 3 minutes, and 5 to 60 minutes. During the 5 to 60 minutes, the test sheet was taken out every 5 minutes to check whether it broke.

[0024] [Table 1]

[0025] Oil resistance (time to cracking) indicates the maximum treatment time during which the test sheet 1 did not break when bent during test times of 1 minute, 3 minutes, and 5 to 60 minutes (however, tests were conducted every 5 minutes). For example, 1 indicates that there was no rupture at 1 minute but rupture at 3 minutes, 5 indicates that there was no rupture at 5 minutes but rupture at 10 minutes, and 35 indicates that there was no rupture at 35 minutes but rupture at 40 minutes. >60 indicates that there was no change in the test sheet 1 60 minutes after the start of the test, and <1 indicates that the test sheet 1 broke when bent with fingers after being left for 1 minute. By comparing the Examples containing all of the components (A) to (C) with the Comparative Examples not containing any of the components (A) to (C), it was confirmed that the Examples had excellent oil resistance. In particular, Example 1, which was made of a combination of components (A), (B), and (C-1) and had a higher PLA content than Examples 2 and 3, had excellent oil resistance in both the MD and TD directions. [Industrial Applicability]

[0026] The oil-resistant sheet obtained from the oil-resistant resin composition of the present disclosure can be used as a manufacturing material for containers (various containers for food, daily necessities, electric and electronic devices and parts, mechanical devices and parts, miscellaneous goods, etc.), as well as containers for filling with liquids such as beverages, food containers (containers for prepared foods, containers for lunch boxes, confectionery containers, etc.), drug containers, containers for ovens and microwave ovens, containers into which boiling water is poured (containers for instant foods, etc.), containers subjected to heat sterilization, non-heated containers, etc. Furthermore, it can be used as an inner liner sheet used in food containers, and as a covering material for covering food. [Explanation of symbols]

[0027] 1 Test sheet 2 Oil-containing absorbent cotton 10 Jig 11, 12 Support plate 13 Substrate 20 units (test units)

Claims

1. (A) A mixture molded body of high impact polystyrene (HIPS) and crystallized polylactic acid (crystalline PLA), (B) one or more thermoplastic elastomers selected from styrene-butadiene-styrene block polymers, hydrogenated styrene-ethylene-butylene-styrene block polymers, and hydrogenated styrene-ethylene-propylene-styrene block polymers; and (C) An oil-resistant resin composition containing (C-1) amorphous polylactic acid (amorphous PLA) or (C-2) HIPS contained separately from the HIPS contained in the component (A).

2. 2. The oil-resistant resin composition according to claim 1, wherein the total content of the crystalline PLA and the amorphous PLA in the oil-resistant resin composition is 20 mass% or more.

3. The oil-resistant resin composition according to claim 1, wherein the total content of the crystalline PLA and the amorphous PLA in the oil-resistant resin composition is 20 to 40 mass%.

4. The oil-resistant resin composition according to any one of claims 1 to 3, wherein the content of the (A) component is 50 to 90% by mass, the content of the (B) component is 5 to 25% by mass, and the content of the (C) component is 5 to 25% by mass.

5. An oil-resistant sheet comprising the oil-resistant resin composition according to any one of claims 1 to 4.

6. 6. The oil-resistant sheet according to claim 5, which is a non-oriented sheet.

7. 6. The oil-resistant sheet according to claim 5, which is a single-layer sheet.

8. 6. The oil-resistant sheet according to claim 5, which is an unoriented single-layer sheet.

9. A container comprising the oil-resistant sheet according to any one of claims 5 to 8.

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