Resin composition and molded article containing the same

Abstract

To provide a cellulose powder-containing resin composition which secures enough safety while maintaining excellent moldability, and a molded article containing the same.SOLUTION: A resin composition contains cellulose powder (A), unmodified polyolefin (B), an olefinic elastomer (C), a lubricant (D), and a dispersant (E), wherein when the whole resin composition is 100 pts.mass, 40 to 65 pts.mass of the cellulose powder (A), 20 to 60 pts.mass of the unmodified polyolefin (B), 2 to 12 pts.mass of the olefinic elastomer (C), 1 to 5 pts.mass of the lubricant (D), and 1 to 3 pts.mass of the dispersant (E) are contained, and a ratio of the total mass of the olefinic elastomer (C), the lubricant (D) and the dispersant (E) to the mass of the cellulose powder (A) is less than 0.31.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition containing cellulose powder and a molded article containing the resin composition. [Background technology]

[0002] In recent years, waste from synthetic resin products has become a problem, including the problem of marine plastics. Therefore, there is a demand for reducing the amount of synthetic resin used by converting at least a portion of the raw materials used in synthetic resin products, especially those that are discarded after use, to raw materials other than synthetic resin.

[0003] Examples of raw materials other than synthetic resins include cellulose materials such as paper, which are inexpensive and highly recyclable and are therefore widely used as reinforcing materials for thermoplastic resins and elastomers, which are used to form films and other materials.

[0004] However, when cellulose materials are used as part of the raw materials for synthetic resin products, the composition tends to be harder and more brittle than raw materials made entirely of synthetic resin, which limits the range of uses and makes it difficult to increase the content of cellulose powder.

[0005] Therefore, in Patent Document 1, the applicant proposed a resin composition that has improved moldability by using an olefin-based elastomer in addition to polyethylene as the base resin. This resin composition exhibits good moldability even when the cellulose powder content is increased due to the effect of the elastomer. Therefore, packaging films and the like with high cellulose powder concentrations can be produced using various molding methods such as injection molding and inflation molding. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-152911 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, the resin composition proposed by the applicant in Patent Document 1 satisfies the standards for the heptane elution test stipulated in the Food Sanitation Act when molded into films or other molded articles obtained by diluting and molding the resin composition with a diluent resin such as polyethylene. However, the resin composition before dilution may not meet the standards for the heptane elution test, making it difficult to use the resin composition undiluted for films or other applications that come into direct contact with food. Even when the resin composition is diluted for use, it is difficult to use the resin composition as a raw material in factories that manufacture films or other applications that come into direct contact with food, in order to eliminate the possibility of the undiluted resin composition being mixed into the final product.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a cellulose powder-containing resin composition that maintains excellent moldability while ensuring sufficient safety, and a molded product containing the same. [Means for solving the problem]

[0009] In order to achieve the above object, one embodiment of the resin composition of the present invention is a resin composition containing cellulose powder (A), unmodified polyolefin (B), olefin-based elastomer (C), lubricant (D), and dispersant (E), When the entire resin composition is taken as 100 parts by mass, 40 to 65 parts by mass of the cellulose powder (A), 20 to 60 parts by mass of the unmodified polyolefin (B), 2 to 12 parts by mass of the olefin-based elastomer (C), 1 to 5 parts by mass of the lubricant (D), 1 to 3 parts by mass of the dispersant (E) Contains The ratio of the total mass of the olefin elastomer (C), the lubricant (D) and the dispersant (E) to the mass of the cellulose powder (A) is less than 0.31. [Effects of the Invention]

[0010] The resin composition of the present invention contains components (A) to (E) in the above-described amounts, and the ratio of the total mass of components (C) to (E) to the mass of component (A) is within the above-described range. This allows the amount of olefinic elastomer (C) used to be reduced, thereby reducing the amount of elution in a heptane elution test. Furthermore, the reduction in moldability due to the reduction in the amount of olefinic elastomer (C) used can be compensated for by adding component (D), a non-metallic lubricant, thereby ensuring sufficient moldability of the resin composition. This allows for the production of resin compositions and molded articles that have excellent moldability and meet the heptane elution test standards set forth in the Food Sanitation Act. DETAILED DESCRIPTION OF THE INVENTION

[0011] The resin composition of the present invention will be specifically described below. Note that the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention.

[0012] <Resin composition> The resin composition of the present invention contains cellulose powder (A), unmodified polyolefin (B), olefin-based elastomer (C), lubricant (D), and dispersant (E) (in this specification, each component may be simply referred to as "component (A)"). The resin composition may further contain other components as necessary.

[0013] <Cellulose powder (A)> The cellulose powder of component (A) can be produced, for example, by using pulp derived from refined, highly pure cotton linters, wood, bamboo, bagasse, etc., and pulverizing the pulp in a mill such as a knife mill, vertical roller mill, or jet mill to obtain powdered pulp as a raw material, followed by classifying the powder to obtain a desired average particle size.

[0014] The average particle size of the cellulose powder is not intended to be limited, but is, for example, 36 μm or less, preferably 32 μm or less, and more preferably 30 μm or less. If the average particle size exceeds 36 μm, the surface of the resin composition becomes rough and the cellulose powder becomes non-uniformly dispersed, which may make it difficult to manufacture the resin composition and molded articles. If the average particle size is 36 μm or less, the surface of the resin composition becomes smooth and the cellulose powder is uniformly dispersed, eliminating holes due to drawdown during extrusion and making it easier to accommodate fine structures during injection. Therefore, the resin composition has excellent moldability and toughness.

[0015] The average particle size of the cellulose powder is not intended to be limited, but is, for example, 6 μm or more, preferably 8 μm or more, more preferably 10 μm or more, and particularly preferably 13 μm or more. If the average particle size is less than 6 μm, the cellulose powder will be bulky, which may make it difficult to produce a resin composition and a molded article. Furthermore, the surface area of ​​the cellulose powder increases, requiring an increased amount of dispersant or the like to cover it, resulting in poor physical properties of the molded article. If the average particle size is 6 μm or more, the rigidity of the resin composition will be excellent, and the bulkiness of the cellulose powder will be reduced, making it easier to produce a resin composition and a molded article.

[0016] In this specification, the term "average particle size" refers to the 50% particle size (D50), which can be measured as the volume average particle size using a laser diffraction particle size distribution analyzer (a dry particle size distribution analyzer manufactured by Malvern Instruments, trade name: MASTER SIZER 3000) or the like.

[0017] The aspect ratio of the cellulose powder is preferably 2 or less, and more preferably 1.8 or less. During molding such as inflation molding, the cellulose powder tends to be oriented in the MD direction. By setting the aspect ratio to 2 or less, the anisotropy of the orientation of the cellulose powder is reduced and the isotropy is improved.

[0018] The "aspect ratio" refers to the ratio L / D of the long diameter L to the short diameter D of the cellulose powder, and is obtained by observing the cellulose powder with a microscope (for example, a digital microscope manufactured by Keyence Corporation, product name: VHX-7000) and analyzing the obtained images, and then calculating the average aspect ratio for 100 particles.

[0019] Commercially available cellulose powder may be used, such as cellulose microfiber ARBOCEL (registered trademark) manufactured by Rettenmeyer Japan Co., Ltd., powdered cellulose KC Flock (registered trademark) manufactured by Nippon Paper Industries Co., Ltd., and pulp powder manufactured by TDI Corporation.

[0020] The content of the cellulose powder is 40 to 65 parts by mass, preferably 40 to 60 parts by mass, based on 100 parts by mass of the entire resin composition. If the content of the cellulose powder is less than 40 parts by mass, the cellulose powder content of the molded product will be limited. If the amount of cellulose powder blended exceeds 65 parts by mass, it may be difficult to produce the resin composition and molded product.

[0021] From the viewpoint of further improving the physical properties required for the molded article, the cellulose powder content in the molded article is preferably 60% by mass or less, more preferably 55% by mass or less. The lower limit of the cellulose powder content in the molded article is not particularly limited, but can be, for example, 10% by mass or more, preferably 20% by mass or more.

[0022] <Unmodified polyolefin (B)> Examples of the unmodified polyolefin of component (B) include unmodified polyethylene and unmodified polypropylene, with unmodified polyethylene being preferred.

[0023] Examples of unmodified polyethylene that can be used include ethylene homopolymers such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and ultra low density polyethylene (ULDPE), and these may be used alone or in combination of two or more. In particular, the polyethylene preferably contains one or more of low density polyethylene, linear low density polyethylene, and ultra low density polyethylene.

[0024] As an unmodified polyolefin, low-density polyethylene (density: 0.900 to 0.935 g / cm 3 Such low-density polyethylene is less likely to lose flexibility even when combined with cellulose powder to form a resin composition, and is easily compatible with elastomers, improving the production stability of the resin composition.

[0025] Furthermore, it is preferable that the resin composition contains linear low-density polyethylene (LLDPE) or low-density polyethylene obtained by a metallocene catalyst as the unmodified polyolefin, which improves the sliding properties of the resin composition and makes it suitable for producing screw-shaped molded products such as container lids that are frequently opened and closed.

[0026] Furthermore, it is preferable that the unmodified polyolefin contains ultra-low density polyethylene (ULDPE), which has a specific gravity of less than 0.90 and can effectively reduce the specific gravity of the molded article.

[0027] When the total resin composition is taken as 100 parts by mass, the content of the unmodified polyolefin is 20 to 60 parts by mass, preferably 20 to 56 parts by mass, more preferably 20 to 41 parts by mass, and particularly preferably 22 to 40 parts by mass. If the amount of unmodified polyolefin is less than 20 parts by mass, the resin composition may become hard and brittle, and the proportion of cellulose powder may increase, making production difficult. If the content of unmodified polyolefin is more than 60 parts by mass, the proportion of cellulose powder in the resin composition may decrease.

[0028] <Olefin elastomer (C)> The olefinic elastomer of component (C) has better conformability to cellulose powder during molding than general thermoplastic resins, and the inclusion of the olefinic elastomer improves the moldability of the resin composition.

[0029] The olefin elastomers used in the present invention include copolymers or homopolymers mainly composed of an olefin having 3 or more carbon atoms, and copolymers mainly composed of ethylene and an olefin having 3 or more carbon atoms.

[0030] More specifically, examples include propylene-ethylene copolymer, ethylene-propylene-diene terpolymer, etc. The olefin-based elastomer may be used alone or in combination of two or more kinds.

[0031] Furthermore, olefin-based elastomers are generally composed of hard segments that control basic physical properties such as mechanical properties, and soft segments that control elasticity, a rubber-like property. Olefin-based elastomers whose hard segments consist of polypropylene are called propylene-based elastomers, and those whose hard segments consist of polyethylene are called ethylene-based elastomers. Examples of soft segments in olefin-based elastomers include EPDM, EPM, EBM, IIR, hydrogenated styrene butadiene rubber (HSBR), NBR, and acrylic rubber (ACM).

[0032] Furthermore, in terms of excellent moldability, particularly low-temperature moldability, of the resin composition as well as excellent toughness, a copolymer containing propylene as the main component (for example, the above-mentioned "propylene-ethylene copolymer") or a propylene-based elastomer which is a homopolymer of propylene is preferred.

[0033] In the case of a propylene-based elastomer, the content of propylene units relative to all units is preferably 70% by mass to 95% by mass, more preferably 80% by mass to 90% by mass. If the content of propylene units, which are hard segments, is 70% by mass or more, strength is improved, resulting in excellent moldability, while if it is 95% by mass or less, excellent stretchability is obtained due to the elasticity of the soft segments.

[0034] The content of the olefin-based elastomer is 2 to 12 parts by mass, preferably 2 to 9 parts by mass, based on 100 parts by mass of the entire resin composition. If the content of the olefin-based elastomer is less than 2 parts by mass, the resin composition may become hard and brittle, and strand surfaces may become rough, resulting in poor productivity. If the content of the olefin-based elastomer is more than 12 parts by mass, molding is possible, but it may be difficult to meet the standards for the heptane elution test.

[0035] When a propylene-based elastomer is used as the olefin-based elastomer, the melt mass flow rate (MFR) of the propylene-based elastomer is, but is not intended to be limited to, preferably 1 to 30 g / 10 min, and more preferably 3 to 16 g / 10 min, for example, MFR1 (described below). If the propylene-based elastomer has an MFR1 of 1 g / 10 min or more, the resin composition will have excellent moldability and rigidity, and if it is 30 g / 10 min or less, the resin composition will have excellent moldability and toughness.

[0036] The melt mass flow rate described above can be obtained by measuring in accordance with the provisions of JIS K 7210-1:2014, and the measurement conditions for the propylene-based elastomer in this application are the conditions described in the Examples.

[0037] The MFR can be measured under the conditions of a temperature of 230°C and a load of 2.16 kg for general polypropylene-based resins, and a temperature of 190°C and a load of 2.16 kg for general polyethylene-based resins.

[0038] The melting point or softening point of the propylene-based elastomer is preferably 50 to 160° C., more preferably 50 to 110° C., and even more preferably 50 to 80° C. If the melting point or softening point of the propylene-based elastomer is 50° C. or higher, the toughness of the resin composition will be superior, and if it is 160° C. or lower, the rigidity of the resin composition will be superior.

[0039] The "melting point" refers to the melting initiation temperature on a DSC chart in a differential scanning calorimeter (DSC), and the "softening point" refers to the Vicat softening temperature measured in accordance with JIS K 7206:2016.

[0040] <Lubricant (D)> The lubricant (D) forms a film on the surface of the material and the metal surface of the processing machine during the production of the resin composition, improving lubrication and reducing the load acting on these surfaces, thereby facilitating processing. Adding the lubricant component (D) to the resin composition improves the granulation properties of the resin composition. The lubricant is not particularly limited, and any common lubricant can be used. Specific examples of lubricants include fatty acids such as stearic acid, fatty acid metal salts such as zinc stearate, barium stearate, and calcium stearate, fatty acid amide compounds such as stearic acid amide and erucic acid amide, and polyhydric alcohol fatty acid esters formed by ester bonds between polyhydric alcohols and fatty acids. Polyhydric alcohol fatty acid esters are particularly preferred as lubricants. Polyhydric alcohol fatty acid esters tend to inhibit the function of the dispersant (E), especially when the dispersant (E) contains MA-PO, which is advantageous in ensuring excellent physical properties of thin films. The lubricant may also function as a dispersant or compatibilizer.

[0041] The fatty acids contained in the lubricant, particularly the fatty acids contained in the polyhydric alcohol fatty acid ester, may be either straight-chain or branched-chain fatty acids, and may be either saturated or unsaturated. Fatty acids having 6 to 24 carbon atoms are preferred. Examples of such fatty acids include stearic acid, isostearic acid, ricinoleic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, isoarachidic acid, behenic acid, caprylic acid, 2-ethylhexanoic acid, isononanoic acid, capric acid, lauric acid, myristic acid, isomyristic acid, erucic acid, palmitic acid, isopalmitic acid, and citric acid. From the viewpoint of ensuring sufficient moldability of the resin composition and good physical properties of the molded article, preferred fatty acids are stearic acid, erucic acid, palmitic acid, and citric acid. These fatty acids may be used alone or in combination.

[0042] The polyhydric alcohol contained in the polyhydric alcohol fatty acid ester is not particularly limited as long as it is an alcohol containing two or more hydroxyl groups in one molecule. Specific examples of the polyhydric alcohol include ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanedioic acid. and trihydric or higher polyhydric alcohols such as trimethylolethane, trimethylolpropane, trimethylolbutane, ditrimethylolpropane, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, polyglycerin (e.g., glycerin dimer to 20-mer), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol-glycerin condensates, adonitol, arabitol, xylitol, and mannitol.Further examples include sugars that are trihydric or higher polyhydric alcohols such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose, gentianose, and melenitose. From the viewpoints of availability and ease of reaction with fatty acids, it is preferable to use glycerin, polyglycerin, sorbitol, sorbitan, alkylene glycols such as ethylene glycol and propylene glycol and polymers thereof, pentaerythritol, dipentaerythritol, trimethylolpropane, etc. These polyhydric alcohols may be used alone or in combination of two or more.

[0043] It is particularly preferable to use a triglyceride composed of glycerin and a fatty acid and / or a fatty acid derivative as the polyhydric alcohol fatty acid ester, such as 12-hydroxystearic acid triglyceride.

[0044] The content of lubricant (D) is 1 to 5 parts by mass, preferably 1 to 4.7 parts by mass, based on 100 parts by mass of the entire resin composition. If the amount of lubricant (D) is less than 1 part by mass, it may not perform as a lubricant and the strand surface of the resin composition may become rough. If the content of lubricant (D) exceeds 5 parts by mass, it may become difficult to ensure good physical properties of the molded product.

[0045] <Dispersant (E)> The dispersant (E) primarily acts on the interface of fillers such as cellulose powder to inhibit aggregation between fillers and promote the dispersion of the filler in the resin component. In addition to improving the dispersibility of the filler, the dispersant may also function as a compatibilizer, improving the compatibility between the filler and the resin component. The inclusion of a dispersant in a resin composition makes it easier for cellulose powder to disperse in the resin composition and molded articles containing it. In addition, when the dispersant also functions as a compatibilizer, the affinity between the cellulose powder and the resin in the resin composition and molded articles is increased, improving the appearance and physical properties of the molded articles. The dispersant may also function as a lubricant. The dispersant is not particularly limited as long as it can provide sufficient dispersibility of the cellulose powder in the resin composition, and any known dispersant can be used. Specific examples of dispersants include thermoplastic resins such as polyolefins modified with acid anhydrides such as maleic anhydride and succinic anhydride, and polyhydric alcohol fatty acid esters exemplified in the section on lubricant (D). In particular, the dispersant preferably contains at least one of maleic anhydride-modified polyolefins (hereinafter sometimes referred to as "MA-PO") and glycerin fatty acid esters. Examples of glycerin fatty acid esters include saturated fatty acid monoglycerides of citric acid.

[0046] Examples of MA-PO include α-olefin-maleic anhydride copolymers, mixtures of α-olefin polymers and maleic anhydride, and mixtures of α-olefins, α-olefin-maleic anhydride copolymers and maleic anhydride. Examples of α-olefins include ethylene and propylene.

[0047] The content of dispersant (E) is 0.8 to 4 parts by mass, preferably 1 to 3 parts by mass, based on 100 parts by mass of the entire resin composition. If the content of dispersant (E) is less than 0.8 parts by mass, the cellulose powder will not be sufficiently compatible with unmodified polyolefin or olefin-based elastomer and will aggregate, which may reduce the dispersibility of the cellulose powder and reduce moldability. If the content of dispersant (E) exceeds 4 parts by mass, the strength and solvent resistance of the molded product may decrease.

[0048] When the dispersant (E) contains MA-PO, the melt viscosity of the MA-PO is preferably 100 to 15,000 mPa s, and more preferably 120 to 11,000 mPa s. When the melt viscosity of the MA-PO is 100 mPa s or higher, the resin composition has excellent moldability and toughness, and when it is 15,000 mPa s or lower, the resin composition has excellent rigidity.

[0049] The "melt viscosity" refers to the viscosity measured by a capillary rheometer.

[0050] When the dispersant (E) contains MA-PO, the acid value of MA-PO is preferably 2 to 150 mgKOH / g, more preferably 3 to 120 mgKOH / g. When the acid value of MA-PO is 5 mgKOH / g or more, the resin composition has excellent moldability, and when it is 150 mgKOH / g or less, the resin composition has excellent appearance.

[0051] The "acid value" refers to a value measured by potentiometric titration as defined in JIS K 2501 or a value measured in accordance with JIS K 0070.

[0052] When dispersant (E) contains MA-PO, the weight-average molecular weight of the MA-PO may be, but is not limited to, for example, 1,000 or more, preferably 2,000 or more, and more preferably 7,000 or more, and the weight-average molecular weight of the MA-PO may be, but is not limited to, for example, 100,000 or less, preferably 80,000 or less, and more preferably 70,000 or less.

[0053] The weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC) as described below.

[0054] Other ingredients The resin composition may further contain other components in addition to the above-mentioned components (A) to (E), as necessary, such as additives such as a compatibilizer, a thermoplastic resin, an anti-seizure agent, an MFR adjuster, a stabilizer, an antioxidant, an antistatic agent, and a colorant. The compatibilizer acts at the interface between a filler such as cellulose powder and a resin component, improving compatibility (adhesion) at the interface and promoting the dispersion of the filler into the resin component. The inclusion of a compatibilizer in a resin composition facilitates the dispersion of cellulose powder in the resin composition and molded articles containing the same, enhancing the affinity between the cellulose powder and the resin, thereby improving the appearance and physical properties of the molded articles. The materials added as the lubricant (D) and dispersant (E) may also function as compatibilizers. The compatibilizer may be, but is not limited to, any of the materials exemplified above for lubricant (D) and dispersant (E), which function as compatibilizers, or other commonly known compatibilizers. Among the materials exemplified above for lubricant (D) and dispersant (E), preferred examples of materials functioning as compatibilizers include MA-PO and polyhydric alcohol fatty acid esters. Furthermore, although there is no intention to limit the thermoplastic resin, for example, a composition similar to that of the thermoplastic resin for dilution described below can be used.

[0055] When the resin composition contains a compatibilizer as another component, the amount of the compatibilizer blended is, for example, 0.5 to 5 parts by mass, preferably 1 to 4 parts by mass, and can further be 1.2 to 3 parts by mass, relative to 100 parts by mass of the entire resin composition. The amount of components other than the compatibilizer, relative to 100 parts by mass of the entire resin composition, is preferably less than 5 parts by mass, more preferably less than 4 parts by mass.

[0056] ≪Mass ratio≫ In the resin composition of the present invention, the mass M of the cellulose powder (A) A The mass M of the olefinic elastomer (C) C and the mass of lubricant (D) M D and the mass M of the dispersant (E) E The ratio of the total mass of the C +M D +M E ) / M A is less than 0.31. C +M D +M E ) / M A is preferably less than 0.30, more preferably less than 0.284.

[0057] Mass ratio (M C +M D +M E ) / M A By setting the value of the solubility of the polymer in the above range, it is possible to obtain a resin composition that satisfies the standards of the heptane elution test.

[0058] <Heptane elution test> The heptane elution test prescribed by the Food Sanitation Act (hereinafter referred to as the "statutory method") is specified in the "Specifications and Criteria for Foods, Food Additives, etc. (Ministry of Health and Welfare Notification No. 370 of 1959)" (https: / / www.mhlw.go.jp / content / 000757879.pdf).

[0059] Here, as an alternative to the statutory method, the following small-scale heptane elution test (hereinafter also referred to as the "heptane elution test (alternative method)" or "alternative method") is used for evaluation.

[0060] [Heptane elution test (alternative method)] (a) preparing a sheet of the resin composition by press molding; (b) Cut the sheet to a sample surface area of ​​10 cm 2 Get a sample of; (c) 20 mL of heptane (special grade) as a test solution is placed in a beaker, and the sample is immersed in the test solution at 25°C for 1 hour; (d) removing the sample from the test solution, heating the test solution with an electric heater to evaporate it to dryness, and leaving it to cool at room temperature for 24 hours; (e) Calculate the evaporation residue (amount of elution) based on the difference in mass of the beaker before and after evaporation.

[0061] Regarding alternative methods, the conditions and procedures required for testing other than those described in the above procedures shall be the same as those for the statutory method.

[0062] The legal method requires a sample with a surface area of ​​100 cm 2 and 200 mL of heptane is used (sample surface area 1 cm 2 (2 ml of heptane per 1 cm sample surface area) 2 By reducing the sample surface area while maintaining the legally required heptane usage ratio of 2 ml per 100 ml, the amount of heptane used is reduced. This not only enables low-cost, environmentally friendly testing, but also eliminates the need for the concentration step using an evaporator required by the legally required method in the process of evaporating the test solution to dryness.

[0063] As will be described later, when comparing the results of the leaching amount between the legal method and the alternative method, the results of both methods are almost identical when the leaching amount is small (specifically, for example, when it is 100 μg / mL or less). Furthermore, when the leaching amount is large (specifically, when it is greater than 100 μg / mL), the leaching amount is greater with the alternative method than with the legal method. In other words, the alternative method can be used for measurements under stricter conditions than the legal method, making it useful as an alternative to the legal method.

[0064] For the resin composition of the present invention, the amount of elution in a heptane elution test (alternative method) is preferably 150 μg / mL or less, more preferably 145 μg / mL or less, even more preferably 110 μg / mL or less, and particularly preferably 100 μg / mL or less.

[0065] This enables the resin composition to meet the standard of 150 μg / mL or less set forth in the heptane elution test (statutory method) for "synthetic resin implements or container packaging whose main components are polyethylene and polypropylene."

[0066] The above does not exclude the use of the legal method for heptane elution testing. When using the legal method, the elution amount must be 150 μg / mL or less.

[0067] Furthermore, since the molded article of the present invention is produced by adding a thermoplastic resin for dilution to the resin composition as needed, if the resin composition satisfies the standard for the amount of elution in the heptane elution test, the molded article will naturally satisfy the standard.

[0068] <Method of manufacturing resin composition> An example of a method for producing a resin composition will be described below.

[0069] The resin composition is preferably in the form of a masterbatch, preferably in the form of pellets, although this is not limited thereto. This allows smooth feeding from a hopper to a screw in a process using an extruder, making it suitable for moldings with various cellulose contents and produced by various molding methods, and also makes it easier to handle since it is less likely to scatter than a powder.

[0070] In this case, first, cellulose powder (A) and dispersant (E) are mixed in a predetermined mixing ratio, and then the resulting mixture is mixed with unmodified polyolefin (B), olefin-based elastomer (C), lubricant (D), and any other components in a predetermined mixing ratio, and the mixture is melt-kneaded at a predetermined temperature in a co-rotating twin-screw extruder equipped with a strand die and extruded into strands. The extruded mixture is then cut to obtain pellets of the resin composition.

[0071] Examples of the mixing method include dry blending using a super mixer, a Henschel mixer, etc. In this case, from the viewpoint of increasing the mixing efficiency of the cellulose powder (A) and the dispersant (E), for example, if the dispersant (E) is in the form of pellets, it may be crushed in advance before being mixed with the cellulose powder (A).

[0072] <Molded products> ≪Applications≫ The uses of the molded articles are not intended to be limited, but specific examples include containers for food, medicine, and cosmetics, tableware such as cups, plates, forks, and spoons, outer bags for packaging food and sanitary products, films for shopping bags, garbage bags, and various other daily necessities and industrial products. In particular, the resin composition of the present invention satisfies the standards of the heptane elution test (legal method), and therefore the molded article is suitable as an outer packaging material for food. Note that when the molded article is a film, the film may be used as a single layer, but from the viewpoint of improving the functionality of the film, such as formability, printability, and sealability, another layer such as a surface layer may be provided on one or both sides of the film to form a multilayer film.

[0073] <Nominal tensile strain at break> The nominal tensile strain at break [%] of a film (cellulose powder 30% by mass, thickness 120 μm) formed using the resin composition of the present invention is preferably more than 10% in both the MD and TD directions, and more preferably 500% or more.

[0074] The nominal tensile strain at break can be measured by the method described in the Examples.

[0075] <Method of manufacturing molded products> An example of the method for producing the molded article of the present invention will be described below.

[0076] A resin compound is prepared by mixing pellets of the resin composition described above with optional components such as a diluent thermoplastic resin (F) and various additives, as needed. The resin compound may be obtained, for example, by dry-blending the pellets of the resin composition described above with the thermoplastic resin (F) and the like using a Supermixer, Henschel mixer, or the like before feeding them into a molding machine, or by feeding them into the molding machine in the desired order and kneading them in the molding machine. In this specification, the term "resin compound" is a concept that includes both the above-mentioned dry-blended state and the state in which they are kneaded in the molding machine.

[0077] The resin compound is then molded using any of a variety of commonly known molding methods, such as blow molding, inflation molding, injection molding, and extrusion molding, to obtain the molded article of the present invention.

[0078] The resin composition may be used as it is in various molding processes as a resin compound.

[0079] For example, when injection molding is used as a molding method, various molded products are produced by injection molding a resin compound at a predetermined temperature.

[0080] Furthermore, for example, when inflation molding is used as a molding method, a resin compound is melt-extruded at a predetermined temperature in a twin-screw extruder equipped with a circular die to form a film, and the film-like material is then wound up on a take-up roll to produce a molded product such as a film.

[0081] Furthermore, for example, when blow molding is used as a molding method, a cylindrical parison is molded by melt extrusion at a predetermined temperature using a resin compound in an extruder, and the parison is then sandwiched between blow molding dies, and air is blown into the parison to form a hollow body, thereby producing a molded product such as a container.

[0082] ≪Thermoplastic resin (F)≫ Examples of thermoplastic resins for dilution of component (F) include polyethylene-based resins, polypropylene-based resins, polystyrene-based resins, polyurethane-based resins, polyvinyl alcohol-based resins, and ethylene-vinyl acetate copolymer resins. The thermoplastic resins may be used alone or in combination of two or more. In particular, polyethylene-based resins are preferred from the viewpoints of cost advantage, excellent cold resistance, excellent waterproofing, and ability to prevent moisture absorption by cellulose.

[0083] In addition, examples of polyethylene-based resins that can be used include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (ULDPE). One type of polyethylene-based resin may be used alone, or two or more types may be used in combination.

[0084] In particular, the thermoplastic resin preferably contains one or more of low-density polyethylene, linear low-density polyethylene, and high-density polyethylene.

[0085] It is preferable to use low-density polyethylene as the thermoplastic resin, because it is less likely to lose flexibility when combined with cellulose powder to form a resin composition and is easily miscible with elastomers. In particular, the use of linear low-density polyethylene (LLDPE) results in good elongation and tear strength in the molded product.

[0086] Furthermore, when linear low-density polyethylene (LLDPE) or low-density polyethylene obtained by a metallocene catalyst is used as the thermoplastic resin, the sliding properties are improved, and therefore the resin compound of the present invention is particularly suitable for molded articles having a screw shape, such as container lids that are frequently opened and closed.

[0087] The content of the thermoplastic resin (F) when the entire molded article is taken as 100 parts by mass is not intended to be limited, but is, for example, 60 parts by mass or less, preferably 20 parts by mass or more and 55 parts by mass or less. If the content of the thermoplastic resin (F) is more than 70 parts by mass, the proportion of cellulose powder in the molded article decreases.

[0088] The thermoplastic resin (F) may be the same as or different from the unmodified polyolefin (B).

[0089] <Effects> The resin composition of the present invention contains components (A) to (E) in the above-described amounts, and the ratio of the total mass of components (C) to (E) to the mass of component (A) is within the above-described range. This allows the amount of olefinic elastomer (C) used to be reduced, thereby reducing the amount of elution in a heptane elution test. Furthermore, the reduction in moldability due to the reduction in the amount of olefinic elastomer (C) used can be compensated for by adding component (D), a non-metallic lubricant, thereby ensuring sufficient moldability of the resin composition. This allows for the production of resin compositions and molded articles that have excellent moldability and meet the heptane elution test standards set forth in the Food Sanitation Act. [Example]

[0090] The present invention will be described below based on examples. However, the present invention is not limited to these examples, and these examples can be modified or changed based on the spirit of the present invention, and such modifications are not excluded from the scope of the present invention.

[0091] <Material> The materials used in the examples, comparative examples, and reference examples are shown below. Note that MFR1 is a value measured under the conditions of a temperature of 190°C and a load of 2.16 kg in accordance with the provisions of JIS K 7210-1:2014, and MFR2 is a value measured under the conditions of a temperature of 230°C and a load of 2.16 kg in accordance with the provisions of JIS K 7210-1:2014. (1) Cellulose powder (A) (1-1) Cellulose powder 1 (average particle size: 18 μm, aspect ratio: 1.5, manufactured by Rettenmeyer Japan Co., Ltd., product name: ARBOCEL (registered trademark) BE600-10TG) (1-2) Cellulose powder 2 (average particle size: 10 μm, aspect ratio: 1.8, manufactured by Rettenmeyer Japan Co., Ltd., product name: ARBOCEL (registered trademark) UFC100) (1-3) Cellulose powder 3 (pulp powder made by finely grinding dry sheets of Kraft hardwood bleached pulp (LBKP) as raw material, average particle size: 27.7 μm, aspect ratio: 1.7, density: 1.53 g / cm 3 , manufactured by TDI Corporation, product name: VP-1) (2) Unmodified polyolefin (B) (2-1) LDPE (low-density polyethylene, density: 0.922 g / cm 3 , MFR1: 2g / 10min, manufactured by Lotte Chemical Co., Ltd., product name: TITANLENE (registered trademark) LDF200YZ) (2-2) LLDPE (linear low-density polyethylene, density: 0.913 g / cm 3 , MFR1: 2g / 10min, manufactured by Prime Polymer Co., Ltd., product name: Evolue (registered trademark) SP1520) (3) Olefin-based elastomer (C) (3-1) Propylene-based elastomer 1 (propylene-ethylene copolymer, ethylene unit content: 16% by mass, MFR1: 1.4 g / 10 min, MFR2: 3 g / 10 min, softening point: 53.9°C, manufactured by ExxonMobil, trade name: Vistamaxx (registered trademark) 6102FL) (3-2) Propylene-based elastomer 2 (propylene-ethylene copolymer, ethylene unit content: 6% by mass, MFR2: 10,000 g to 100,000 g / 10 min (actual measurement is impossible, so a converted value based on melt viscosity is shown), melting point: 97°C, manufactured by ExxonMobil, trade name: Vistamaxx (registered trademark) 8880) The MFR1 of a 1:1 mixture (mass ratio) of the propylene-based elastomer 1 and the propylene-based elastomer 2 was 15.4 g / 10 min. (4) Lubricant (D) Polyhydric alcohol fatty acid ester (12-hydroxystearic acid triglyceride, manufactured by Riken Vitamin Co., Ltd., trade name: Rikemal (registered trademark) TG-12) (5) Dispersant (E) (5-1) MA-PO-1 (maleic anhydride-modified polypropylene, melting point: 166°C, melt viscosity: 10.4 Pa s, acid value: 22.8 mg KOH / g (JIS K 2501), weight-average molecular weight Mw: 6.5 × 10 4 , manufactured by Riken Vitamin Co., Ltd., product name: RikeAid (registered trademark) MG-250P) (5-2) MA-PO-2 (maleic anhydride-modified polypropylene, melting point: 136°C, melt viscosity: 120 mPa s, acid value: 3.5 mg KOH / g (JIS K 0070), weight-average molecular weight Mw: 9 × 10 3 (Catalog value, high-temperature GPC method), Sanyo Chemical Industries, Ltd., product name: Umex (registered trademark) 100TS) (5-3) MA-PO-3 (olefin wax, α-olefin-maleic anhydride copolymer: 66.8% by mass, α-olefin polymer: 32.9% by mass, maleic anhydride: 0.3% by mass, melting point: 70 to 76°C, melt viscosity: 140 to 210 mPa s, acid value: 95 to 110 mg KOH / g (JIS K 2501), weight average molecular weight Mw: 6.7 × 10 3 , manufactured by Mitsubishi Chemical Corporation, product name: Diakarna (registered trademark) 30M) (5-4) Glycerin fatty acid ester (citric acid saturated fatty acid monoglyceride, manufactured by Riken Vitamin Co., Ltd., trade name: Poem (registered trademark) K-30P) (6)Compatibilizer (manufactured by Sun Ace Co., Ltd., product name: MF-1) (7)Anti-eye varnish agent (fatty acid metal salt-based additive, base polymer: low-density polyethylene (density: 0.9 g / cm 3 ), MFR1: 6.3 g / 10 min, masterbatch containing 10% by mass of magnesium 12-hydroxystearate, manufactured by Katsuta Chemical Co., Ltd., product name: AP-600P) (8)Anti-foaming agent (calcium oxide, master pellet containing 65% by mass of calcium oxide and 35% by mass of LLDPE as the base polymer, manufactured by Omi Chemical Industry Co., Ltd., product name: BELL-CML EM) <Average particle size and aspect ratio of cellulose powder> The average particle size of the cellulose powder was measured using a laser diffraction particle size distribution analyzer (dry particle size distribution meter manufactured by Malvern, product name: MASTER SIZER 3000). [[ID=第十二条]]

[0092] [[ID=第十三条]] The aspect ratio of the cellulose powder was determined as the average value of the aspect ratios calculated by analyzing images of 100 particles using a microscope (digital microscope manufactured by Keyence Corporation, product name: VHX-7000) and the software attached to the microscope. [[ID=第十六条]]

[0093] [[ID=第十七条]] <Weight-average molecular weights of MA-PO-1 and MA-PO-2> The weight-average molecular weights Mw of MA-PO-1 and MA-PO-2 were measured according to the following measurement methods and conditions.

[0094] GPC device: manufactured by Tosoh Corporation, product name HLC-8321GPC / HT (detector: RI)) Column: manufactured by Tosoh Corporation, product name: TSKgel guardcolumnH HR (39)HT (7.5 mm I.D. × 7.5 cm) × 1 piece + manufactured by Tosoh Corporation, product name: TSKgel GMH HR -H (20)HT (7.8 m I.D. × 30 cm) × 3 pieces Eluent: 1,2,4-trichlorobenzene (for GPC manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) + BHT (0.05%) Flow rate: 1.0mL / min Detection condition: polarity=(-) Injection volume: 0.3mL Column temperature: 140℃ System temperature: 40°C Sample concentration: 1 mg / mL Calibration curve: quintic approximation curve using standard polystyrene manufactured by Tosoh Corporation Molecular weight: Polystyrene equivalent molecular weight Pretreatment: The sample was weighed, an eluent was added, and the sample was dissolved by shaking at 140°C for 1 hour. After that, the sample was heated and filtered using a sintered filter with a pore size of 0.5µm. No insoluble matter was found by visual inspection.

[0095] <Preparation of Resin Composition> According to the formulations shown in Table 1, resin compositions of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared in the following manner.

[0096] [Table 1]

[0097] Specifically, first, cellulose powder and MA-PO were mixed in a supermixer to obtain a mixture.

[0098] Next, the obtained mixture and the remaining raw materials were melt-kneaded in a co-rotating twin-screw extruder under conditions of a molding temperature of 150 to 210°C and a screw rotation speed of 40 to 120 rpm, and extruded into strands with a diameter of 2 to 4 mm. The extruded kneaded material was then cut to obtain pellets of the resin composition.

[0099] <Heptane elution test (alternative method)> For each of the resin compositions of Examples 1 to 8 and Comparative Examples 1 to 5, the amount of elution was measured by a heptane elution test (alternative method) using the following steps (a) to (e).

[0100] (a) A sheet (thickness: 45 μm) of the resin composition was prepared by press molding; (b) The sheet was cut by punching with a 5 cm × 1 cm die, and the sample surface area was 10 cm 2obtained samples of; (c) 20 mL of heptane (special grade) as a test solution was placed in a beaker, and the sample was immersed in the test solution at 25°C for 1 hour; (d) Each sample was taken out of each test solution, and the test solution was heated with an electric heater to evaporate to dryness, and then allowed to stand at room temperature for 24 hours to cool; (e) The evaporation residue (amount of elution) was calculated based on the difference in mass of the beaker before and after evaporation.

[0101] Regarding alternative methods, the conditions and procedures required for testing other than those described in the above procedures shall be the same as those for the statutory method.

[0102] The obtained elution amounts are shown in Table 1. The elution amounts were evaluated as follows: ◯ when the elution amount was 150 μg / mL or less, and × when it was more than 150 μg / mL. The evaluation results are shown in Table 1.

[0103] <Comparison between statutory and alternative methods> To compare the legal method and the alternative method for the heptane elution test, the elution amounts were measured by both the legal method and the alternative method for the resin compositions of Reference Examples 1 to 3 shown in Table 2. The measurement by the legal method was outsourced to the Japan Food Research Laboratories.

[0104] [Table 2]

[0105] For the resin compositions of Reference Examples 1 and 2, the amounts eluted by both methods were substantially the same. Furthermore, for the resin composition of Reference Example 3, the amount eluted by the alternative method was greater than that by the legal method. This experiment demonstrated that resin compositions with elution amounts of 150 μg / mL or less by the alternative method fulfill the legal standard of 150 μg / mL or less, and that the alternative method is useful as an alternative to the legal method.

[0106] <Manufacturing method for molded products (films)> The obtained pellets of the resin compositions of Examples 1 to 8 and Comparative Examples 1 to 5 were dry-blended with a thermoplastic resin, additives, etc. in the proportions shown in Table 1 to obtain resin compounds.

[0107] The resulting resin compound was melt-kneaded in a single-screw extruder at a molding temperature of 150-210°C and a screw rotation speed of 60 rpm, then introduced into a circular die for inflation molding, followed by air cooling to solidify and winding on a winder. The film width (the width when the inflation-molded product is folded; i.e., the molded product is formed into a cylindrical shape with a circumference of 280 mm) was 140 mm and the thickness was 120 μm. The screw specifications were full flight, L / D: 25, C / R: 3.08.

[0108] <Measurement of nominal tensile strain at break> The nominal tensile break strain [%] of the obtained film was measured in accordance with JIS K 7161-1. More specifically, a dumbbell-shaped No. 3 test piece (gauge length: 20 mm) specified in JIS K 6251 was cut from the obtained film. The nominal tensile break strain in the MD and TD directions of the test piece was then determined using a precision universal testing machine (Shimadzu Corporation, Autograph AG-5000A) under conditions of a temperature of 23°C, a relative humidity of 50%, and a test speed of 200 mm / min ±10%. The results are shown in Table 1.

[0109] <Consideration> As shown in Table 1, the resin compositions of Examples 1 to 8 had elution amounts of 150 μg / mL or less in the heptane elution test (alternative method), which was found to satisfy the statutory standard.

[0110] On the other hand, the resin compositions of Comparative Examples 1 to 5 had elution amounts exceeding 150 μg / mL in the heptane elution test (alternative method), which was found to not satisfy the statutory standard.

[0111] Furthermore, the nominal tensile strain at break of the molded articles was comparable to that of Examples 1 to 8 and Comparative Examples 1 to 5, and showed sufficiently high values, demonstrating that the strength of the molded articles was excellent.

[0112] That is, it was found that the resin composition of the present invention satisfies the standards of the heptane elution test under the Food Sanitation Act, and that molded articles thereof have sufficiently high strength and can ensure excellent physical properties. [Industrial Applicability]

[0113] The present invention is useful in the fields of resin compositions and molded articles containing cellulose powder.

Claims

1. A resin composition containing cellulose powder (A), an unmodified polyolefin (B), an olefin-based elastomer (C), a lubricant (D), and a dispersant (E), When the entire resin composition is taken as 100 parts by mass, 40 to 65 parts by mass of the cellulose powder (A), 20 to 60 parts by mass of the unmodified polyolefin (B), 2 to 12 parts by mass of the olefin-based elastomer (C), 1 to 5 parts by mass of the lubricant (D), 0.8 to 4 parts by mass of the dispersant (E) Contains A resin composition, wherein the ratio of the total mass of the olefin-based elastomer (C), the lubricant (D), and the dispersant (E) to the mass of the cellulose powder (A) is less than 0.

31.

2. The resin composition according to claim 1, wherein the unmodified polyolefin (B) is a low-density polyethylene and / or a linear low-density polyethylene.

3. The lubricant (D) contains a polyhydric alcohol fatty acid ester, The resin composition according to claim 1, wherein the polyhydric alcohol fatty acid ester is a triglyceride composed of glycerin and a fatty acid and / or a fatty acid derivative.

4. The resin composition according to claim 1 , wherein the dispersant (E) comprises at least one of a maleic anhydride-modified polyolefin and a glycerin fatty acid ester.

5. The dispersant (E) contains a maleic anhydride-modified polyolefin, The resin composition according to claim 1, wherein the maleic anhydride-modified polyolefin has a weight average molecular weight of 7,000 or more.

6. A molded article comprising the resin composition according to any one of claims 1 to 5.

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