Resin composition and molded product comprising the same

Abstract

To provide a resin composition capable of producing a molded product having excellent moldability and high practicality, even when using a cellulose powder having a relatively large average particle diameter and a molded product comprising the same.SOLUTION: There is provided a resin composition comprising a cellulose powder (A), an unmodified polyolefin (B), an olefin-based elastomer (C), a lubricant (D) and a maleic anhydride-modified polyolefin (E), wherein when the total amount of the resin composition is defined as 100 pts.mass, the resin composition comprises 45 to 65 pts.mass of the cellulose powder (A), 20 to 40 pts.mass of the unmodified polyolefin (B), 4 to 14 pts.mass of the olefin-based elastomer (C), 2 to 6 pts.mass of the lubricant (D) and 0.8 to 3 pts.mass of the maleic anhydride-modified polyolefin (E) and the content of the cellulose powder (A) and the content and the acid value of the maleic anhydride-modified polyolefin (E) satisfy predetermined conditions.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 has a cellulose powder with an average particle size of 10 μm or less. Generally, the smaller the average particle size of the cellulose powder, the higher the cost and number of steps required for production, resulting in a problem of limited applications. Therefore, from the perspective of enabling the use of cellulose powder with a larger average particle size, there is room for improvement in the technology of Patent Document 1.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a resin composition that has excellent moldability and can produce highly practical molded articles even when cellulose powder having a relatively large average particle size is used, and a molded article 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), an unmodified polyolefin (B), an olefin-based elastomer (C), a lubricant (D), and a maleic anhydride-modified polyolefin (E), When the entire resin composition is taken as 100 parts by mass, 45 to 65 parts by mass of the cellulose powder (A), 20 to 40 parts by mass of the unmodified polyolefin (B), 4 to 14 parts by mass of the olefin-based elastomer (C), 2 to 6 parts by mass of the lubricant (D), 0.8 to 3 parts by mass of the maleic anhydride-modified polyolefin (E) Contains The content of the cellulose powder (A) and the content and acid value of the maleic anhydride-modified polyolefin (E) satisfy the following conditions. [conditions] Formula 1: X = content (parts by mass) of the maleic anhydride-modified polyolefin (E) ÷ content (parts by mass) of the cellulose powder (A) × acid value (mg KOH / g) of the maleic anhydride-modified polyolefin (E) When the value X in the formula 1 is 1.6 or more and 3.6 or less. (However, when a mixture of multiple types of maleic anhydride-modified polyolefins is used as the maleic anhydride-modified polyolefin (E), the value X in the formula 1 is calculated for each type of the multiple types of maleic anhydride-modified polyolefins, and the total value is 1.6 or more and 3.6 or less.) [Effects of the Invention]

[0010] The resin composition of the present invention contains the components (A) to (E) in the above-mentioned amounts and satisfies the above-mentioned conditions, so that even when a cellulose powder having a relatively large average particle size is used, a resin composition with excellent moldability can be obtained, and highly practical molded products can be produced. 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), olefinic elastomer (C), lubricant (D), and maleic anhydride-modified polyolefin (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, 10 μm or more, preferably 18 μm or more, and more preferably 24 μm or more. If the average particle size is less than 10 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 compatibilizer to cover it, resulting in poor physical properties of the molded article. If the average particle size is 10 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 ARBOCEL (registered trademark) cellulose microfiber manufactured by Rettenmeyer Japan Co., Ltd., KC Flock (registered trademark) powdered cellulose manufactured by Nippon Paper Industries Co., Ltd., and cellulose powder manufactured by TDI Corporation.

[0020] The content of the cellulose powder is 45 to 65 parts by mass, preferably 50 to 62 parts by mass, based on 100 parts by mass of the entire resin composition. If the content of the cellulose powder is less than 45 parts by mass, the cellulose powder content of the molded product will be limited. If the blending amount of the cellulose powder 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] The content of unmodified polyolefin is 20 to 40 parts by mass, preferably 32 to 40 parts by mass, and more preferably 37 to 40 parts by mass, based on 100 parts by mass of the entire resin composition. If the amount of polyethylene 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 polyethylene content is more than 40 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 4 to 14 parts by mass, preferably 6 to 12 parts by mass, and more preferably 6 to 10 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 4 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 14 parts by mass, molding may be difficult, or even if molding is possible, it may be difficult to obtain a molded product that is practical in terms of physical properties such as strength.

[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 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 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 differential scanning calorimeter (DSC) chart.

[0040] <Lubricant (D)> Adding a lubricant (component (D)) to the resin composition improves the granulation properties of the resin composition. The lubricant is not particularly limited, but specific examples 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 bonding between polyhydric alcohols and fatty acids. It is particularly preferred to use polyhydric alcohol fatty acid esters as the lubricant.

[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 8 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, palmitic acid, and isopalmitic acid. From the viewpoint of ensuring sufficient moldability of the resin composition and good physical properties of the molded article, preferred fatty acids include stearic acid, erucic acid, and palmitic 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 the lubricant is 2 to 6 parts by mass, preferably 3 to 5 parts by mass, based on 100 parts by mass of the entire resin composition. If the amount of the lubricant is less than 2 parts by mass, the lubricant may not function properly and the strand surface of the resin composition may become rough. If the amount of the lubricant exceeds 6 parts by mass, it may become difficult to ensure good physical properties of the molded product.

[0045] <Maleic anhydride modified polyolefin (E)> Component (E), maleic anhydride-modified polyolefin (also known as "MA-PO"), functions as a compatibilizer. The inclusion of MA-PO facilitates dispersion of cellulose powder in resin compositions and molded articles, and enhances the affinity between the cellulose powder and resin, improving physical properties.

[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 MA-PO is 0.8 to 3 parts by mass, preferably 1 to 2.8 parts by mass, based on 100 parts by mass of the entire resin composition. If the content of MA-PO 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 MA-PO exceeds 3 parts by mass, the strength and solvent resistance of the molded product may decrease.

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

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

[0050] The acid value of MA-PO is preferably 5 to 150 mgKOH / g, and more preferably 20 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. When the acid value of MA-PO is expressed as a range of values, the acid value used in Equation 1 below is the average value of the maximum and minimum values.

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

[0052] The weight average molecular weight of the maleic anhydride-modified polyolefin (E) is not intended to be limited, but may be, for example, 1,000 or more, preferably 2,000 or more. The weight average molecular weight of the maleic anhydride-modified polyolefin (E) is not intended to be limited, but may be, for example, 100,000 or less, preferably 80,000 or less, more preferably 60,000 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 cellulose powder, unmodified polyolefin, olefin-based elastomer, and MA-PO, as necessary. Examples of other components include thermoplastic resins and additives such as anti-seizure agents, MFR adjusters, stabilizers, antioxidants, antistatic agents, and colorants. The thermoplastic resin may have a similar structure to the thermoplastic resin used for dilution, which will be described later, but is not intended to be limiting.

[0055] The content of the other components is preferably less than 5 parts by mass, more preferably less than 4 parts by mass, when the total amount of the resin composition is 100 parts by mass.

[0056] ≪Conditions≫ In the resin composition of the present invention, the content of the cellulose powder (A) and the content and acid value of the maleic anhydride-modified polyolefin (E) satisfy the following conditions. [conditions] Formula 1: X = content (parts by mass) of the maleic anhydride-modified polyolefin (E) ÷ content (parts by mass) of the cellulose powder (A) × acid value (mg KOH / g) of the maleic anhydride-modified polyolefin (E) When the value X in the formula 1 is 1.6 or more and 3.6 or less, preferably 1.7 or more and 3.0 or less. (However, when a mixture of multiple types of maleic anhydride-modified polyolefins is used as the maleic anhydride-modified polyolefin (E), the value X in the formula 1 is calculated for each type of the multiple types of maleic anhydride-modified polyolefins, and the total value is 1.6 or more and 3.6 or less, preferably 1.7 or more and 3.0 or less.) The acid value of the maleic anhydride-modified polyolefin (E) is an index corresponding to the amount of maleic anhydride segments present in the molecule. The amount of maleic anhydride segments affects the dispersibility of cellulose powder particles. In particular, as the average particle size of the cellulose powder (A) increases, the surface area of ​​the cellulose powder particles decreases. Therefore, it is desirable to improve the dispersibility of the cellulose powder particles by adjusting the amount of maleic anhydride segments in the maleic anhydride-modified polyolefin relative to the cellulose powder content.

[0057] The value X calculated by the above formula 1 can be said to represent the ratio of maleic anhydride segments in the maleic anhydride-modified polyolefin (E) to the cellulose powder (A). If the value X is less than 1.6, the performance of the maleic anhydride-modified polyolefin (E) as a dispersant may be insufficient, and the cellulose powder particles may not be uniformly dispersed. On the other hand, if the value X exceeds 3.6, the ratio of maleic anhydride segments is too high, and the cellulose powder particles may re-agglomerate, again resulting in the cellulose powder not being uniformly dispersed.

[0058] In this way, by adjusting the mass and acid value of the maleic anhydride-modified polyolefin (E) relative to the mass of the cellulose powder (A), it is possible to ensure uniform dispersibility of the cellulose powder, even when a cellulose powder with a relatively large average particle size is used, and to obtain a resin composition with excellent moldability.

[0059] <Method of manufacturing resin composition> An example of a method for producing a resin composition will be described below.

[0060] 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.

[0061] In this case, first, cellulose powder (A) and MA-PO (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. 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 cut to obtain pellets of the resin composition.

[0062] Examples of mixing methods include dry blending using a super mixer, a Henschel mixer, etc. In this case, in order to improve the mixing efficiency of the cellulose powder (A) and the MA-PO (E), for example, if the MA-PO (E) is in the form of pellets, it may be crushed before mixing with the cellulose powder (A).

[0063] <Molded products> ≪Applications≫ The uses of the molded articles are not intended to be limited, but specific examples include containers for medicines, cosmetics, and food, tableware such as cups, plates, forks, and spoons, sanitary products, outer bags for packaging food, films for shopping bags, garbage bags, and various other daily commodities and industrial products.

[0064] <Film thickness> When a film is produced as a molded product using the resin composition of the present invention, the film thickness may be a value obtained by a commonly known method, such as a value measured with a dial gauge or a value calculated from a scanning electron microscope (SEM) image or a digital microscope image. Furthermore, although not intended to be limiting, if the film tends to have unevenness and the difference between thick and thin areas tends to be large, the film thickness may be expressed in terms of basis weight, since dial gauge measurements may only provide the thickness of the thick areas. Alternatively, the film thickness may be expressed using a film thickness (theoretical value) calculated based on the density and basis weight of each material constituting the film.

[0065] The validity of using the basis weight and the film thickness (theoretical value) calculated from the basis weight as the film thickness was also examined.

[0066] Specifically, the film thickness (theoretical value) calculated from the basis weight was compared with the film thickness calculated from a microscopic image of the cross section of the film observed with a digital microscope using the following procedure.

[0067] That is, three types of films were used, using the same materials and formulation as in Example 1 described below, with film thicknesses (theoretical values) of 70 μm, 79 μm, and 102 μm calculated from the basis weight. The cross-sectional area of ​​the film and the film length (maximum diameter) giving the cross-sectional area were calculated from digital microscope images (magnification: 100x, 10 visual fields). The cross-sectional area obtained for each visual field was then divided by the maximum diameter to calculate the film thickness for each visual field. The average thickness obtained for the 10 visual fields was then used as the film thickness.

[0068] For three types of film with thicknesses (theoretical values) calculated from the basis weight of 70 μm, 79 μm, and 102 μm, the film thicknesses calculated from digital microscope images were 75 μm, 81 μm, and 102 μm, respectively, and no significant difference was observed between them. From these results, it was found that it is appropriate to use the basis weight of the film and the thickness (theoretical value) calculated from the basis weight as the film thickness.

[0069] The basis weight of the film is not intended to be limited, but from the viewpoint of obtaining a thinner and more practical film, it is set to 150 g / m 2 Preferably, it is 120 g / m or less. 2 More preferably, it is 100 g / m or less. 2 It is more preferable that it is less than 10 ...

[0070] The film thickness (theoretical value) of the film is not intended to be limited, but from the viewpoint of obtaining a thinner and more practical film, it is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably less than 100 μm.

[0071] <Tensile strength> The tensile strength [MPa] of a film (cellulose powder 30% by mass, film thickness (theoretical value) 120 μm) formed using the resin composition of the present invention is preferably 6 MPa or more in the MD direction or the TD direction, more preferably 9 MPa or more, and particularly preferably 11.8 MPa or more.

[0072] The tensile strength can be measured by the method described in the Examples.

[0073] <Nominal tensile strain at break> The nominal tensile strain at break [%] of a film (cellulose powder 30% by mass, film thickness (theoretical value) 120 μm) formed using the resin composition of the present invention is preferably more than 3% in both the MD and TD directions, more preferably 300% or more, and particularly preferably 400% 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 the components (A) to (E) in the above-mentioned amounts and satisfies the above-mentioned conditions, so that even when a cellulose powder having a relatively large average particle size is used, a resin composition with excellent moldability can be obtained, and highly practical molded products can be produced. [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 and comparative 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 stipulations 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 stipulations of JIS K 7210-1:2014. (1) Cellulose powder 1 (average particle size: 30 μm, aspect ratio: 1.7, density: 1.53 g / cm 3 , manufactured by TDI Corporation, product name: VP-1) (2) Cellulose powder 2 (average particle size: 30 μm, aspect ratio: 1.8, density: 1.53 g / cm 3 , manufactured by Rettenmaier Japan Co., Ltd., product name: ARBOCEL (registered trademark) BE600-30) (3) Cellulose powder 3 (average particle size: 18 μm, aspect ratio: 1.5, density: 1.53 g / cm 3 , manufactured by Rettenmaier Japan Co., Ltd., product name: ARBOCEL (registered trademark) BE600-10TG) (4) 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) (5) 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) (6) Propylene-based elastomer 1 (propylene-ethylene copolymer, ethylene unit content: 16 mass%, density: 0.862 g / cm 3 , MFR1: 1.4 g / 10 min, MFR2: 3 g / 10 min, melting point: 55°C, manufactured by ExxonMobil, trade name: Vistamaxx (registered trademark) 6102FL) (7) Propylene-based elastomer 2 (propylene-ethylene copolymer, ethylene unit content: 6 mass%, density: 0.879 g / cm 3MFR2: 10,000g to 100,000g / 10min (actual measurement is not possible, so a converted value based on melt viscosity is listed), melting point: 97°C, manufactured by ExxonMobil, product name: Vistamaxx (registered trademark) 8880) The MFR1 of a 1:1 mixture (mass ratio) of propylene-based elastomer 1 and propylene-based elastomer 2 was 15.4 g / 10 min (Examples 1, 3 to 6, Comparative Examples 1 to 3). The MFR1 of a 5:3 mixture (mass ratio) of propylene-based elastomer 1 and propylene-based elastomer 2 was 7.5 g / 10 min (Example 2). (8) Lubricant 1 (polyhydric alcohol fatty acid ester: 12-hydroxystearic acid triglyceride, density: 0.888 g / cm 3 , manufactured by Riken Vitamin Co., Ltd., product name: Rikemal (registered trademark) TG-12) (9) Lubricant 2 (fatty acid metal salt additive, density: 1.1 g / cm 3 , NOF Corporation, product name: Zinc Stearate GP) (10) MA-PO-1 (olefin wax, α-olefin-maleic anhydride copolymer: 66.8 mass%, α-olefin polymer: 32.9 mass%, maleic anhydride: 0.3 mass%, density: 0.95 g / cm 3 , melting point: 70 to 76°C, melt viscosity: 140 to 210 mPa·s, acid value: 95 to 110 mgKOH / g (wherein the acid value in formula 1 was the average value of the maximum value 110 mgKOH / g and the minimum value 95 mgKOH / g, 102.5 mgKOH / g), weight average molecular weight Mw: 6.7 × 10 3 , manufactured by Mitsubishi Chemical Corporation, product name: Diakarna 30M) (11) MA-PO-2 (maleic anhydride modified polypropylene, density: 0.93 g / cm 3 , melting point: 166°C, melt viscosity: 10.4 Pa s, acid value: 22.8 mg KOH / g, weight average molecular weight Mw: 6.5 × 10 4 , manufactured by Riken Vitamin Co., Ltd., product name: RikeAid (registered trademark) MG-250P) (12) Anti-foaming agent (calcium oxide, master pellet containing 65% by mass of calcium oxide and 35% by mass of LLDPE as the base polymer, density: 1.73 g / cm 3 , 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 measuring device (dry particle size distribution meter manufactured by Malvern, product name: MASTER SIZER 3000).

[0092] The aspect ratio of the cellulose powder was calculated as the average value of the aspect ratios obtained 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.

[0093] <Weight-average molecular weight of MA-PO> The weight-average molecular weight Mw of MA-PO was 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) + BHT (0.05%) Flow rate: 1.0 mL / min Detection conditions: polarity = (-) Injection volume: 0.3 mL Column temperature: 140 °C System temperature: 40 °C Sample concentration: 1 mg / mL Calibration curve: 5th-order 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 6 and Comparative Examples 1 to 3 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] <Condition> The value X of the following formula 1 was calculated for the resin compositions of Examples 1 to 6 and Comparative Examples 1 to 3. The results are shown in Table 1. Formula 1: X = content (parts by mass) of the maleic anhydride-modified polyolefin (E) ÷ content (parts by mass) of the cellulose powder (A) × acid value (mg KOH / g) of the maleic anhydride-modified polyolefin (E) In Example 5 and Comparative Example 2, in which a mixture of MA-PO-1 and MA-PO-2 was used as the maleic anhydride-modified polyolefin (E), the value X in Equation 1 for each of Example 5 and Comparative Example 2 was the sum of the value X1 calculated using the content and acid value of MA-PO-1 and the value X2 calculated using the content and acid value of MA-PO-2.

[0100] As shown in Table 1, it was found that the resin compositions of Examples 1 to 6 had a value X of 1.6 or more and 3.6 or less in formula 1, whereas the resin compositions of Comparative Examples 1 to 3 did not satisfy this numerical range.

[0101] <Manufacturing method for molded products (films)> The obtained pellets of the resin compositions of Examples 1 to 6 and Comparative Examples 1 to 3 were dry-blended with a thermoplastic resin, additives, etc. in the proportions shown in Table 1 to obtain resin compounds.

[0102] The resin compounds obtained in Examples 1 to 6 were melt-kneaded in a single-screw extruder at a molding temperature of 150 to 210°C and a screw rotation speed of 60 rpm, then introduced into a circular die and blown into a film. The film was then cooled and solidified by air cooling, and wound up on a winder. The film width (the width of the blown-in-film molded article when folded; i.e., the molded article was molded into a cylindrical shape with a circumference of 280 mm) was 140 mm, and the theoretical film thickness was 70 to 120 μm. The screw specifications were full flight, L / D: 25, C / R: 3.08.

[0103] Inflation molding was attempted using the resin compounds of Comparative Examples 1 to 3 by the method described above, but holes due to drawdown were found to be significant, and films suitable for practical use could not be obtained.

[0104] <Moldability (blowing film molding)> In the above-mentioned manufacturing method of the molded article (film), the case where the moldable article was possible was evaluated as ◯, and the case where the moldable article was not possible was evaluated as ×. The results are shown in Table 1.

[0105] <Basis weight> Six measurement samples, each 70 mm wide and 150 mm long, were cut out from the resulting film, each cut out from a random location at an interval of 50 cm or more.

[0106] The mass of each measurement sample was measured using a high-precision digital balance (manufactured by Ishida Corporation, model number UB-H620), and the mass per unit area was calculated. The average value of the mass per unit area calculated for each measurement sample was used as the basis weight of the film (g / m 2 ) was decided.

[0107] <Film thickness (theoretical value)> When the mass of the film is m, the area is S, the density is p, and the basis weight is Z, the film thickness (theoretical value) is calculated as d using the following formula 2. Note that m / S is equal to the basis weight Z. The density p of the film was calculated based on the density and blending ratio of each material. The results are shown in Table 1.

[0108] Equation 2: d=m / Sp=Z / p <Measurement of tensile strength> ·MD direction The obtained film was cut into a dumbbell shape (JIS K 6251 dumbbell No. 3, both end width: 25 mm, total length: 100 mm, gauge length: 20 mm, width: 5 mm) extending in the MD direction to prepare a test piece. A tensile test was performed on the test piece in accordance with JIS K7127 at a temperature of 23°C and a relative humidity of 50% RH at a pulling rate of 200 mm / min to measure the tensile strength of the film in the MD direction.

[0109] ·TD direction The obtained film was cut into a dumbbell shape (JIS K 6251 dumbbell No. 3, both end width: 25 mm, total length: 100 mm, gauge length: 20 mm, width: 5 mm) extending in the TD direction to prepare a test piece. A tensile test was performed on the test piece in accordance with JIS K7127 at a temperature of 23°C and a relative humidity of 50% RH at a pulling rate of 200 mm / min to measure the tensile strength of the film in the TD direction.

[0110] <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.

[0111] <Quality evaluation> The resulting films were evaluated for quality according to the following criteria, with the ranking decreasing in the order A → B → C → D. A: Meets all of the following criteria: film thickness (theoretical value) less than 100 μm, formability evaluation of ○ (formable), and high film strength (the smaller of the MD / TD tensile strength values ​​is 11.8 MPa or more). B: Meets all of the criteria: the film thickness (theoretical value) is less than 100 μm and the formability is evaluated as ○ (formable). C: The film thickness (theoretical value) is 100 μm or more and 120 μm or less, and the moldability evaluation is ○ (moldable). D: The moldability was evaluated as × (unmoldable).

[0112] <Consideration> As shown in Table 1, it was found that the resin compositions of Examples 1 and 2 could provide thin films with a thickness of less than 100 μm and excellent strength.

[0113] It was also found that the resin compositions of Examples 3 and 4 were capable of producing thin films with a thickness of less than 100 μm that were sufficiently practical.

[0114] Furthermore, it was found that in Examples 5 and 6, films with thicknesses of 100 μm or more and 120 μm or less could be obtained.

[0115] In other words, in the resin compositions of Examples 1 to 6, even when cellulose powder with a relatively large average particle size was used, it is believed that by adjusting the ratio of maleic anhydride segments of the maleic anhydride-modified polyolefin (E) to the cellulose powder (A), uniform dispersion of the cellulose powder particles could be ensured, and thin, highly practical films could be obtained.

[0116] On the other hand, molding was not possible and films could not be obtained from the resin compositions of Comparative Examples 1 to 3. This is thought to be because the ratio of the maleic anhydride segments of the maleic anhydride-modified polyolefin (E) to the cellulose powder (A) was too high or too low, and the cellulose powder particles were not uniformly dispersed.

[0117] From the above results, it was found that the resin composition of the present invention has excellent moldability even when cellulose powder having a relatively large average particle size is used, and highly practical molded articles can be produced. [Industrial Applicability]

[0118] 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 maleic anhydride-modified polyolefin (E), When the entire resin composition is taken as 100 parts by mass, 45 to 65 parts by mass of the cellulose powder (A), 20 to 40 parts by mass of the unmodified polyolefin (B), 4 to 14 parts by mass of the olefin-based elastomer (C), 2 to 6 parts by mass of the lubricant (D), 0.8 to 3 parts by mass of the maleic anhydride-modified polyolefin (E) Contains A resin composition, wherein the content of the cellulose powder (A), and the content and acid value of the maleic anhydride-modified polyolefin (E) satisfy the following conditions: [conditions] Formula 1: X = content (parts by mass) of the maleic anhydride-modified polyolefin (E) ÷ content (parts by mass) of the cellulose powder (A) × acid value (mg KOH / g) of the maleic anhydride-modified polyolefin (E) When the value X of the formula 1 is 1.6 or more and 3.6 or less. (However, when a mixture of multiple types of maleic anhydride-modified polyolefins is used as the maleic anhydride-modified polyolefin (E), the value X in the above formula 1 is calculated for each type of the multiple types of maleic anhydride-modified polyolefins, and the total value is 1.6 or more and 3.6 or less.)

2. The resin composition according to claim 1, wherein the cellulose powder (A) has an average particle size of 10 μm or more and 36 μm or less.

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

4. The resin composition according to claim 1 , wherein the lubricant (D) is a polyhydric alcohol fatty acid ester.

5. A molded article comprising the resin composition according to any one of claims 1 to 4.

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