Biomass plastic film and production method of the same

Abstract

To provide a new resin molded article which is a resin molded article comprising a resin composition containing wheat flour powder and / or wheat bran, and has an additional added value beyond an environmental load viewpoint.SOLUTION: A biomass plastic film is obtained by molding with drawing a resin composition containing wheat flour powder and / or wheat bran, a polyolefin resin, and a compatibility accelerator. A production method of the biomass plastic film includes the steps of: a composition production step of obtaining a resin composition by kneading a raw material composition containing wheat flour powder and / or wheat bran, a polyolefin resin, and a compatibility accelerator in the presence of water while releasing water vapor at a heat-flow temperature of the polyolefin resin, and cooling the product to the heat-flow temperature or less followed by solidification; and a drawing step of extracting a thermoplastic composition containing the resin composition under heat flow and performing molding with drawing.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention belongs to the technical field of resin molded products. The present invention relates to a resin composition containing a biomass raw material and a resin molded product made from the resin composition. [Background technology]

[0002] From the viewpoint of reducing carbon dioxide emissions that contribute to global warming, the possibility of using reproducible and inexpensive plant-derived components such as cellulose and starch has been studied in various technical fields. In the field of resin molding technology, plant-derived components have long been used, for example, as fillers and blended into resin compositions, but in recent years in particular, research has been progressing on so-called polymer blends in which starch is blended with an appropriate plasticizer to produce thermoplastic starch (TPS) that can be melt-processed, and this TPS is melt-kneaded with a general-purpose thermoplastic synthetic resin.

[0003] On the other hand, wheat is one of the crops that is widely cultivated worldwide and whose main component is starch. Its seeds are ground into powder (flour) and used as an ingredient for bread, noodles, confectionery, etc. During the flour milling process, a large amount of wheat bran is generated. Wheat bran is a by-product consisting of the pulverized outer layer (large bran) of the wheat seed, the aleurone layer (small bran), and the endosperm. Wheat suet flour is a low-grade flour that contains a large amount of the bran component. Wheat bran and wheat suet flour are rich in crude protein, crude fat, minerals, etc., and most of them are used as livestock feed and fertilizer, but have not been used effectively in other ways.

[0004] In response, a molding resin material containing wheat bran and a thermoplastic resin has been proposed (for example, Patent Document 1). The molding resin material can be produced stably and is said to have excellent carbon neutrality. In addition, biodegradable plastic compositions containing wheat bran and / or wheat starch, and molded articles and laminates using the same have also been proposed (for example, Patent Document 2). The compositions, molded articles, and laminates are said to have excellent not only biodegradability but also mechanical properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Seki No. 2016-50210 [Patent Document 2] JP 2002-363432 A Summary of the Invention [Problem to be solved by the invention]

[0006] Although the resin material described in Patent Document 1 and the plastic composition described in Patent Document 2 may exhibit effective properties from the viewpoint of environmental impact, neither document discloses that they have any added value beyond that as resins or plastics.

[0007] The present invention is a resin molded product made from a resin composition containing wheat bran and / or wheat starch flour, and its main objective is to provide a novel resin molded product that not only has reduced environmental impact but also has additional added value. [Means for solving the problem]

[0008] Wheat husk and its vicinity contain phenolic components such as ferulic acids and alkylresorcinols, and components such as phytic acids that are known to have antioxidant and antibacterial properties. Although biomass plastics have been studied by incorporating wheat bran and wheat starch, which are by-products of wheat flour, into plastic compositions and molded products from the perspective of carbon neutrality, no studies have been conducted on imparting functionality such as antioxidant and antibacterial properties to plastic compositions and molded products.

[0009] As a result of extensive research, the inventors have unexpectedly discovered a new resin composition that has the additional property of antibacterial properties when it is subjected to molding involving stretching of a resin composition containing wheat starch and / or wheat bran, and have thus completed the present invention. The present invention can include, for example, the following.

[0010] [1] A biomass plastic film, characterized in that it is obtained by molding and stretching a resin composition containing wheat flour and / or wheat bran, a polyolefin resin, and a compatibilizer. [2] The biomass plastic film described in [1] above, wherein the molding involving stretching is inflation molding. [3] The biomass plastic film described in [1] above, further containing a chelating agent. [4] The biomass plastic film described in [3] above, wherein the chelating agent is an alkali metal salt of ethylenediaminetetraacetic acid or phytic acid. [5] The biomass plastic film described in [1] above, further containing a dehydrating agent. [6] The biomass plastic film described in [5] above, wherein the dehydrating agent is one or more selected from calcium oxide, magnesium oxide, and burnt dolomite. [7] A bag-shaped product made of the biomass plastic film described in any one of [1] to [6] above.

[0011] [8] A method for producing a biomass plastic film, comprising: a composition production process in which a raw material composition containing wheat flour and / or wheat bran, a polyolefin-based resin, and a compatibilizer is kneaded in the presence of water while releasing water vapor at a temperature at which the polyolefin-based resin becomes thermally fluid, and then cooled to below the thermally fluid temperature to solidify, thereby obtaining a resin composition; and a stretching process in which a thermoplastic composition containing the resin composition is extruded under thermal flow and shaped by stretching. [9] The manufacturing method described in [8] above, wherein the amount of water blended in the composition manufacturing process is within the range of 5 to 50 weight % based on the dry weight of the wheat flour and / or wheat bran blended, and the water content in the thermoplastic composition before molding in the stretching process is 0.5 weight % or less.

[10] The method according to [8] or [9] above, wherein the molding accompanied by stretching in the stretching step is inflation molding.

[11] The method for producing the composition according to [8] or [9] above, further comprising blending a chelating agent as a raw material in the composition production process.

[12] The method according to

[11] above, wherein the chelating agent is an alkali metal salt of ethylenediaminetetraacetic acid or phytic acid.

[13] The method according to [8] or [9] above, wherein in the stretching step, a dehydrating agent is added to the thermoplastic composition before the molding involving the stretching.

[14] The method according to

[13] above, wherein the dehydrating agent is one or more selected from calcium oxide, magnesium oxide, and burnt dolomite. Effect of the Invention

[0012] According to the present invention, a biomass plastic film having practical antibacterial activity against gram-positive and gram-negative bacteria can be obtained from a resin composition containing biomass such as wheat flour or wheat bran. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below. 1. Biomass plastic film according to the present invention The biomass plastic film according to the present invention (hereinafter referred to as the "film of the present invention") is characterized in that it is produced by molding, with stretching, a resin composition containing wheat flour and / or wheat bran, a polyolefin resin, and a compatibilizer. The film of the present invention may contain a chelating agent, a modifier, a dehydrating agent, or the like as raw materials other than those mentioned above.

[0014] Here, "molding involving stretching" refers to molding involving processing that can stretch the resin molecules (polymers) in the resin composition to orient the molecular chains. The molding includes both molding involving biaxial (MD and TD) stretching and molding involving uniaxial (one direction, mainly MD) stretching, and specific examples include T-die extrusion molding (uniaxial stretching, biaxial stretching), inflation molding, blow molding, etc. Among them, inflation molding is more preferable.

[0015] In addition, "molding involving stretching" may be a molding method in which, after various moldings such as press molding, T-die extrusion molding, injection molding, calendar molding, etc., stretching processing is performed using a vacuum molding machine or a stretching machine during secondary processing.

[0016] 1.1 Wheat flour and wheat bran The film of the present invention contains wheat flour and / or wheat bran. The wheat flour and / or wheat bran may be used alone or in combination of any two or more kinds.

[0017] The wheat starch flour is not particularly limited as long as it is a wheat starch flour or its equivalent that is generally available. For example, it is suitable for the wheat starch flour to have an ash content of 1.0 to 3.0% by weight, and preferably has an ash content of 1.2 to 2.0% by weight.

[0018] The wheat bran is not particularly limited as long as it is wheat bran or its equivalent that is generally available on the market. For example, it may be wheat bran obtained by a milling process with a yield of about 80% by weight, or wheat bran obtained by a milling process with a yield of about 60% by weight.

[0019] In the present invention, it is suitable to use wheat bran and / or wheat starch flour having a 90% particle size of 300 μm or less, preferably 250 μm or less, and more preferably 200 μm or less.

[0020] Commercially available wheat flour typically has a particle size distribution in which the 90% particle size is about 200 μm and the 10% particle size is about 10 μm, which is smaller than wheat bran and can be used in the present invention as is.

[0021] The wheat flour can be finely ground to obtain a 90% particle size of 150 μm or less, and the use of such finely ground powder is preferred in the present invention.Furthermore, it is also possible to obtain a particle size of 100 μm or less, and the use of such finely ground powder is even more preferred.

[0022] Moreover, commercially available wheat bran is usually a powder containing particles of various sizes with a particle size distribution in which the 90% particle size is about 1300 μm and the 10% particle size is about 70 μm. If wheat bran containing such large particle size components is directly blended to prepare a composition, the resulting thin molded product such as a film may lack mechanical strength such as tensile strength, have a rough surface, and be of little practical value.

[0023] In the present invention, it is appropriate to use wheat bran obtained by finely pulverizing ordinary wheat bran having a large particle size to obtain wheat bran having a 90% particle size of 300 μm or less. Among them, finely pulverized wheat bran having a 90% particle size of 250 μm or less is preferable, and more preferably having a 90% particle size of 200 μm or less is preferable.

[0024] In the present invention, the smaller the particle size of the wheat bran and / or wheat flour, the better, and there is no particular lower limit. For example, the 90% particle size may be 20 μm or 10 μm, or may be smaller, such as 1.0 μm or 0.5 μm. The particle size may also be smaller than that.

[0025] The particle size and particle size distribution can be determined by a laser diffraction / scattering particle size distribution analyzer. In this specification, the particle size is the particle size in terms of the cumulative value % in the particle size distribution (volume basis) determined by the laser diffraction / scattering method.

[0026] Wheat flour and wheat bran usually contain 5% to 15% moisture. In the present invention, wheat flour and wheat bran having a normal moisture content can be used as is.

[0027] In the film of the present invention, the proportion of wheat bran and wheat starch is suitably in the range of 5.0 to 50% by weight, preferably in the range of 10 to 30% by weight. If the proportion of wheat bran and wheat starch is more than 50% by weight, the molded product may not have good mechanical properties, and if it is less than 10% by weight, it is not preferable from the viewpoint of biomass utilization and may cause problems with antibacterial properties.

[0028] 1.2 Polyolefin resin The film of the present invention contains a polyolefin resin. Such a polyolefin resin is a synthetic resin obtained by polymerizing mainly olefin as a monomer, and is not particularly limited as long as it is a resin that is usually used and processed in molding techniques such as extrusion molding, injection molding, inflation molding, or blow molding, and examples thereof include homopolymers of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, or 1-octene, or copolymers or multistage polymers thereof. In the present invention, the polyolefin resin may be used alone or in combination of any two or more kinds.

[0029] Specific examples of the polyolefin resin include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene, high-density polyethylene (HDPE), ultra-high molecular weight polyethylene, isotactic polypropylene, atactic polypropylene, ethylene-propylene random copolymer, polybutene, ethylene-propylene elastomer, ethylene-vinyl acetate copolymer (EVA), propylene-α-olefin random copolymer, and α-olefin resins mainly composed of α-olefins having 4 or more carbon atoms. An appropriate resin can be selected from these depending on the properties of the desired molded product.

[0030] In the film of the present invention, the proportion of polyolefin resin varies depending on the polyolefin resin and other components used, but is suitably in the range of 10 to 95% by weight, and more preferably in the range of 20 to 90% by weight. If the proportion of polyolefin resin is more than 95% by weight, it is not preferable from the viewpoint of biomass utilization, and there is a risk of causing problems with antibacterial properties, and if it is less than 10% by weight, there is a risk of it being difficult to obtain good mechanical properties of the molded product.

[0031] 1.3 Compatibilizers The film of the present invention may contain a compatibilizer, which may have the function of increasing the compatibility between the polyolefin resin and wheat flour or wheat bran.

[0032] Examples of the compatibilizer include ethylene / acrylate / maleic anhydride copolymer, ethylene / acrylic acid copolymer or ethylene / methacrylic acid copolymer, polyolefin modified with unsaturated carboxylic acid such as maleic anhydride or its derivative, and styrene-maleic anhydride copolymer. Among these, a product obtained by adding maleic anhydride to a relatively low molecular weight polyolefin is preferred because it can exhibit a compatibilizing effect even at a low addition amount. Such maleic anhydride adducts to low molecular weight polyolefins are commercially available, and examples of such products include "UMEX 1001" and "UMEX 1010" (trade name) manufactured by Sanyo Chemical Industries, Ltd., "MODIC-APP908" (trade name) manufactured by Mitsubishi Chemical Corporation, and "ADMER RA104" and "ADMER AT2606" (trade name) manufactured by Mitsui Chemicals, Inc. Although the amount of acid-modifying groups in the maleic anhydride adducts to low molecular weight polyolefins is not particularly limited, a product having a relatively high acid value of about 15 to 80 is preferred. The molecular weight of the low-molecular-weight polyolefin is not particularly limited, but is preferably a relatively low molecular weight, such as a weight-average molecular weight in the range of 10,000 to 200,000, and more preferably in the range of 10,000 to 100,000. By using a maleic anhydride adduct to such a low-molecular-weight polyolefin, it is possible to obtain a high addition effect while suppressing the amount of the compatibilizer added. The above compatibilizers may be used alone or in combination of any two or more kinds.

[0033] The proportion of the compatibilizer in the film of the present invention varies depending on the compatibilizer and other components used, but is suitably in the range of 0.5 to 10% by weight, and more preferably in the range of 1.0 to 6.0% by weight. If the proportion of the compatibilizer is more than 10% by weight, the molded product may not have good mechanical properties, and if it is less than 0.5% by weight, the compatibility between the polyolefin resin and the starch material may not be sufficient.

[0034] 1.4 Chelating agents The film of the present invention may contain a chelating agent. It is known that chelating agents such as EDTA exert antibacterial effects on gram-negative bacteria by affecting cell wall components. However, the effect is said to be limited to gram-negative bacteria (Kida et al., Japanese Journal of Bacteriology, 47, 625 (1992)). In the present invention, the antibacterial properties can be enhanced by using a chelating agent in combination.

[0035] The "chelating agent" according to the present invention is preferably an aminocarboxylic acid-based chelating agent, and examples thereof include ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), dihydroxyethylethylenediaminediacetic acid (DHEDDA), 1,3-propanediaminetetraacetic acid (1,3PDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIMDA), L-aspartic acid-N,N-diacetic acid (ASDA), and alkali metal salts thereof. Among these, alkali metal salts of ethylenediaminetetraacetic acid are preferred. Phytic acid and its alkali metal salts are also preferred. Disodium ethylenediaminetetraacetate and phytic acid are designated as food additives in Japan. The above chelating agents may be used alone or in combination of any two or more kinds.

[0036] The proportion of the chelating agent in the film of the present invention varies depending on the chelating agent and other components used, but is preferably within the range of 0.4 to 4.0% by weight. Of these, the range of 1.0 to 3.0% by weight is more preferable, and the range of 1.5 to 2.5% by weight is even more preferable. If the proportion of the chelating agent is more than 4.0% by weight, the coloring of the film of the present invention may become strong, and if it is less than 0.4% by weight, the antibacterial enhancing effect of the chelating agent may not be sufficiently obtained.

[0037] 1.5 Modifiers The film of the present invention may contain a modifier, if necessary, for the purpose of adjusting the mechanical properties of the resulting molded product and the retention of the antibacterial substance. Examples of the modifier include an emulsifier and a polyhydric alcohol.

[0038] Examples of polyhydric alcohols include glycerin, diglycerin, polyglycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (#200, #300, #400, #600), 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, sorbitol, mannitol, erythritol, xylitol, trehalose, etc. Among these, glycerin and sorbitol are preferred.

[0039] Examples of emulsifiers include nonionic surfactants, and specific examples thereof include monoesters of glycerin with fatty acids having 8 to 20 carbon atoms (e.g., caprylic acid, capric acid, lauric acid, oleic acid, linoleic acid), monoesters of sorbitan with fatty acids having 8 to 20 carbon atoms (e.g., caprylic acid, capric acid, lauric acid, oleic acid, linoleic acid), monoesters of lauric acid of polyglycerin, ethylene oxide adducts of monoglycerides, and ethylene oxide adducts of sorbitan fatty acid monoesters. Among these, monoesters of glycerin with fatty acids having 8 to 20 carbon atoms and monoesters of sorbitan with fatty acids having 8 to 20 carbon atoms are preferred.

[0040] Glycerin monoesters of fatty acids having 8 to 20 carbon atoms and sorbitan monoesters of fatty acids having 8 to 20 carbon atoms can be preferably used for the following reasons. - Small molecular weight, excellent permeability and solubility for starch. - The vapor pressure is low within the processing and use temperature range, making it difficult to volatilize. -High hydroxyl value. High hydrogen bonding ability and high affinity with starch and water. Natural raw materials such as fatty acids and glycerin derived from coconut oil and palm oil, and sugar alcohols derived from starch can be used. The above plasticizers and emulsifiers may be used alone or in combination of any two or more kinds.

[0041] The proportion of the modifier in the film of the present invention varies depending on the modifier and other components used, but is preferably within the range of 0.5 to 12% by weight. Of these, the range of 1.0 to 10% by weight is preferable, and the range of 1.5 to 8.0% by weight is more preferable. If the proportion of the polyhydric alcohol and / or nonionic surfactant is more than 12% by weight, the molded product may not have good mechanical properties, and if it is less than 0.5% by weight, the plasticity and bleeding promotion properties may not be sufficient.

[0042] 1.6 Dehydrating agents The film of the present invention may contain a dehydrating agent in order to avoid deterioration of film quality such as surface roughness caused by micro-foaming during the stretching process. As the dehydrating agent, calcium chloride, silica gel, calcium oxide, calcium hydroxide, magnesium oxide, burned dolomite, burned seashells, etc. can be used. Among them, calcium oxide, magnesium oxide, burned dolomite, and burned seashells are preferable because they have an effect of enhancing the antibacterial properties of the obtained film of the present invention.

[0043] 1.7 Additives, etc. If necessary, the film of the present invention may contain an oxidation stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an inorganic or organic filler, or a colorant such as a dye or a pigment in an appropriate amount within a range that does not impair the effects of the present invention.

[0044] 1.8 Purpose The film of the present invention can be used as a material (biomass plastic film) for producing bag-like products such as packaging bags, carrier bags, vegetable storage bags, garbage bags, etc. The film of the present invention itself can also be formed into the bag-like products and used.

[0045] 2. Method for Producing the Film of the Present Invention The manufacturing method for the film of the present invention (hereinafter referred to as "the manufacturing method of the present invention") is characterized by having a composition production step in which a raw material composition containing wheat flour and / or wheat bran, a polyolefin-based resin, and a compatibilizer is kneaded in the presence of water while releasing water vapor at a temperature at which the polyolefin-based resin undergoes thermal flow, and then cooled to below the thermal flow temperature to solidify, thereby obtaining a resin composition (e.g., resin pellets), and a stretching step in which a thermoplastic composition containing the resin composition is extruded under thermal flow, and shaped with stretching (e.g., thin film formation).

[0046] In this composition production process, a chelating agent, a modifier, and other additives can be blended into the raw material composition as necessary. In addition, in the stretching process, a composition can be made by blending a polyolefin resin, a dehydrating agent, and the like, in addition to the resin composition (resin pellets, etc.) produced in the composition production process.

[0047] 2.1 Composition manufacturing process The manufacturing method of the present invention includes a step of kneading a raw material composition containing wheat flour and / or wheat bran, a polyolefin resin, and a compatibilizer in the presence of water while releasing water vapor at a temperature at which the polyolefin resin becomes thermally fluid, and then cooling the mixture to below the thermal fluidity temperature to solidify the mixture, thereby obtaining a resin composition (composition manufacturing step).

[0048] The use of water is essential in the composition production process. Although it is difficult to perform good molding after this process unless a resin composition in a dry state (i.e., a state with a low water content) is used, it has been unexpectedly found that the use of water in this process is important for realizing the effects of the present invention.

[0049] Bran and wheat bran flour usually contains 5.0 to 15% by weight of moisture. The amount of water added in the composition production process is 5.0 to 50% by weight, preferably 8.0 to 40% by weight, more preferably 10 to 30% by weight based on the dry weight of the bran and wheat bran flour to be added, and the amount added is the amount obtained by subtracting the moisture contained in the bran and wheat bran flour to be added. If the amount is less than 5.0% by weight, the main polymeric components contained in the bran and wheat bran flour may not be sufficiently plasticized, which is not preferable. If the amount is more than 50% by weight, it becomes difficult to dry the composition. The pellets obtained by kneading are dried to pellets with a moisture content of 0.5% by weight or less.

[0050] There is no particular limitation on the type of water that can be used in the present invention. Examples of such water include industrial water, mineral water, tap water, and ion-exchanged water.

[0051] The wheat flour and wheat bran that can be used in the production method of the present invention are the same as the wheat flour and wheat bran that can be contained as components of the film of the present invention, and the appropriate or preferred particle size is also the same.The polyolefin resins that can be used are the same as the polyolefins that can be contained as components of the film of the present invention, and the appropriate or preferred resins that can be used are also the same.

[0052] In the composition production process, other raw materials such as the above-mentioned modifiers, chelating agents, additives, etc. may be blended. By appropriately blending these raw materials, it is possible to finally obtain a biomass plastic film of higher quality.

[0053] In this process, for example, a polyolefin-based resin (hereinafter also referred to as "base resin"), wheat flour and / or wheat bran, a compatibilizer, and if necessary a chelating agent, modifier, and other additives are kneaded in the presence of water at a temperature at which the polyolefin-based resin becomes thermally fluid while releasing water vapor, and then cooled to below the thermal fluidity temperature to solidify, thereby obtaining resin pellets.

[0054] The heat flow temperature is not particularly limited as long as the polyolefin resin used is sufficiently heat-flowable, but is suitably within the range of 60 to 220° C. Among these, the range of 80 to 200° C. is preferable, and the range of 90 to 190° C. is more preferable.

[0055] In the composition production process, for example, a roll mixer, a single screw extruder, a twin screw extruder, a multi-screw extruder, a Banbury mixer, a Henschel mixer, a pressure kneader, etc. can be used. The raw materials can be fed into the continuous production process, for example, by a metering feeder, a metering pump, etc.

[0056] 2.2 Stretching process The production method of the present invention includes a step of extruding the thermoplastic composition containing the resin composition obtained in the composition production step under heat flow and molding with stretching (stretching step). The water content in the thermoplastic composition before molding is suitably, for example, 0.5% by weight or less. In particular, 0.4% by weight or less is preferable, and 0.3% by weight or less is more preferable.

[0057] In the stretching step, molding may be performed without adding any additional resin to the resin composition obtained in the composition production step, or a polyolefin resin (hereinafter also referred to as "diluted resin") may be further added to the resin composition as a diluent during molding. By adding a diluting resin in this step, a resin composition that is more suitable for molding involving stretching can be produced. When a diluting resin is not added in this step, a resin corresponding to the diluting resin may be added in advance with the base resin in the composition production step.

[0058] The base resin and the diluent resin may be the same or different. For example, a propylene-based resin may be used as the base resin and a polyethylene-based resin may be used as the diluent resin, or both of the base resin and the diluent resin may be polyethylene-based resins.

[0059] The molding accompanied by the stretching in the stretching step refers to molding accompanied by processing that can stretch the resin molecules (polymers) in the resin composition to orient the molecular chains, and may be either molding accompanied by biaxial (MD and TD) stretching processing or molding accompanied by uniaxial (one direction, mainly MD) stretching processing. Specific examples include inflation molding, stretched tape molding, and blow molding. Among them, biaxial stretching molding is preferred, and inflation molding is more preferred. In inflation molding, a resin extruded from an extruder is molded into a cylindrical shape through a circular die, and air or a gas such as nitrogen is poured into the molded cylinder to apply biaxial stretching like inflating a balloon.

[0060] The molding accompanied by the stretching may be a molding method in which, after various molding such as press molding, T-die extrusion molding, injection molding, or calendar molding, stretching is performed using a vacuum molding machine or a stretching machine during secondary processing.

[0061] By subjecting the composition to molding involving the above-mentioned stretching, a biomass plastic film having antibacterial properties can be obtained.

[0062] In the stretching process, which involves stretching and thinning, a dehydrating agent can be added as necessary. The pellets obtained in the composition manufacturing process contain highly hydrophilic wheat flour and wheat bran, so some moisture is unavoidable, and this can lead to defects such as surface roughness due to micro-foaming during the stretching process. To avoid this, it is effective to add a dehydrating agent.

[0063] As the dehydrating agent, calcium chloride, silica gel, calcium oxide, calcium hydroxide, magnesium oxide, burnt dolomite, burnt shells, etc. can be used. These dehydrating agents are added in an amount of 0.5% to 6.0% by weight, preferably 1.0% to 4.0% by weight, based on the total dry weight of the compound (raw material composition) used. Among them, calcium oxide, magnesium oxide, burnt dolomite, and burnt shells are preferably used because they have an antibacterial enhancing effect on the obtained film.

[0064] 3. Antibacterial properties of the film of the present invention The film of the present invention has antibacterial properties against gram-positive bacteria and / or gram-negative bacteria. Here, "antibacterial properties" refers to the property of inhibiting bacterial growth. Examples of methods for evaluating the antibacterial properties include the test method of JIS Z 2801 or equivalent tests. In the present invention, the antibacterial activity value obtained by the test is used as one of the evaluation scales, and an activity value of 2.0 or more is considered to have good antibacterial properties.

[0065] Examples of gram-positive bacteria include Staphylococcus aureus, Streptococcus pneumoniae, Staphylococcus epidermidis, Bacillus subtilis, coagulase-negative staphylococci, streptococci, and enterococci. Examples of gram-negative bacteria include Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Salmonella.

[0066] 4. Surface properties of the film of the present invention The surface properties of the film of the present invention, such as surface smoothness, uniformity, colorability, etc., can be further improved by appropriately adjusting the particle size of the wheat bran and / or wheat flour, the amount of water and the amount of dehydrating agent used in the composition production process, the molding temperature, etc.

[0067] From the viewpoint of the surface properties of the film, the particle size of the wheat bran and / or wheat flour is preferably 250 μm or less, more preferably 200 μm or less, in terms of 90% particle size.

[0068] From the viewpoint of the surface properties, the amount of water to be blended in the composition production process is preferably within the range of 8.0 to 40% by weight, based on the dry weight of the bran and wheat flour to be blended, and more preferably within the range of 10 to 30% by weight.

[0069] The amount of the dehydrating agent is preferably within a range of 0.5 to 6.0% by weight, and more preferably within a range of 1.0 to 4.0% by weight, based on the dry weight of the raw material composition of the film of the present invention.

[0070] The molding temperature for the film of the present invention is preferably within the range of 140 to 200°C, and more preferably within the range of 150 to 180°C.

[0071] 5. Strength of the film of the present invention The strength of the film of the present invention can be improved by appropriately adjusting the particle size of the wheat bran and / or wheat flour and the amount of water added in the composition production process. Examples of the evaluation scale of the strength include tensile strength, tensile elongation, and tear strength. EXAMPLES

[0072] The present invention will be described in more detail below with reference to examples and test examples, but the present invention is not limited to these examples in any way.

[0073] (1) Raw materials The raw materials used are as follows: A Polyolefin resin A1: Polypropylene random copolymer "WINTEC WSX03" (Japan Polypropylene Corporation) A2: Polyethylene "Evolue SP1520" (Prime Polymer Co., Ltd.)

[0074] B. Wheat-derived substances (wheat bran, wheat starch) [Wheat bran] B1: Ordinary wheat bran (manufactured by Nitto Fuji Flour Milling Co., Ltd., 10% particle size: 65 μm, 90% particle size: 1,280 μm, moisture content: 8.0%) B2: Wheat bran fine powder (manufactured by Nitto Fuji Flour Milling Co., Ltd., 10% particle size: 7.8 μm, 90% particle size: 180 μm, moisture content: 7.8%) [Wheat flour] B3: General flour (manufactured by Nitto Fuji Flour Mills, 10% particle size: 3.9 μm, 90% particle size: 217 μm, moisture content: 9.6%) B4: Fine powder (manufactured by Nitto Fuji Flour Mills, 10% particle size: 5.3 μm, 90% particle size: 97 μm, moisture content: 9.2%)

[0075] C. Compatibilizer C1: Maleic anhydride modified polypropylene "UMEX 1001" (manufactured by Sanyo Chemical Industries, Ltd.) D Chelating Agent D1: EDTA "Chilest B" (manufactured by Chelest Co., Ltd.) Emulsifier E1: Glycerin monostearate "Rikemal S-100A" (manufactured by Riken Vitamin Co., Ltd.) F Dehydrating agent F1: Calcium oxide "F-Lime-100" (manufactured by Kalfin Co., Ltd.)

[0076] The particle size of wheat-derived substances (wheat bran, wheat flour) was measured using a laser diffraction particle size distribution analyzer manufactured by Shimadzu Corporation. The moisture content was measured using a halogen moisture meter manufactured by AS ONE Corporation at a set temperature of 120°C.

[0077] (2) Production of resin composition Resin compositions were produced in the following manner using the raw material blends shown in Table 1 for antibacterial test samples and Table 2 for surface property and strength test samples, respectively. Here, the weight of each component is the dry weight, and the total amount (100% by weight) used to calculate the blending ratio (% by weight) does not include added water.

[0078] A twin-screw extruder (Technovel KZW25TWIN, screw diameter 48 mm, L / D=60, two vent ports (water vapor release mechanism, type that releases water vapor to atmospheric pressure)) was used as the kneading device, and the raw materials were kneaded at a cylinder temperature of 60-200°C and a screw rotation speed of 100-200 rpm to obtain a resin composition. A metering feeder and a metering pump were used to feed the raw materials, polyolefin resin, wheat bran and / or wheat starch, plasticizer and / or emulsifier, chelating agent, compatibilizer, and water. Following kneading, the kneaded composition was extruded through a strand die set at 100 to 180° C. into a tube shape with a diameter of about 3 mm, pelletized to a length of about 4 mm, and dried to obtain a pellet-shaped resin composition. The water content of each of the resin compositions after drying was 0.3% by weight or less. The water content was measured using a halogen moisture meter manufactured by AS ONE CORPORATION at a set temperature of 120°C.

[0079] (3) Manufacturing of resin molded products The resin compositions thus obtained were used to manufacture resin molded products (molded products of the present invention, etc.) The molding methods used were inflation molding (films of the present invention, Examples 1 to 13) and press molding (Comparative Examples 1 and 2), and the respective resin molded products were obtained. The specific molding method is as follows.

[0080] (3-1) Inflation molding The pellet-shaped resin composition produced above was used to form an inflation film by air cooling. For inflation molding, a single-screw extruder (D=20mm, L / D=25, ring die diameter 25mm) manufactured by Toyo Seiki Seisakusho was used, and molding was performed under the conditions of a screw rotation speed of 42 rpm, a set temperature of 140 to 180°C, a blow-up ratio of about 3.0, and a target thickness of 30μm. Among the polyolefin resins, A2 was used as a diluting resin.

[0081] (3-2) Press film molding The pellet-shaped resin composition produced above was used to perform press film molding. A Tester Sangyo heated press (50 t) was used to form the film, which was melted and pressed at 170° C. and 2 to 5 MPa to form the film into a target thickness of 0.2 to 0.5 mm.

[0082] [Test Example 1] Antibacterial test The antibacterial activity of the surface of the films obtained in (3-1) and (3-2) (Examples 1 to 5 and Comparative Examples 1 and 2) was evaluated by the test method of JIS Z2801. Staphylococcus aureus NBRC 12732 and Escherichia coli NBRC 3972 were used in the test. The antibacterial activity was evaluated by using a commercially available polyethylene film as a control sample and the difference in logarithmic value of the viable cell count after inoculation and culture of the control sample and the test sample as the antibacterial activity value. As the criteria, an antibacterial activity value of 2.0 or more is considered good (◯), and one less than that is considered poor (×). The results are shown in Table 1.

[0083] [Table 1]

[0084] As is clear from Table 1, the films of the present invention according to Examples 1 to 5 have excellent antibacterial activity. In addition, the use of wheat starch rather than wheat bran tends to result in superior antibacterial activity. Therefore, according to the present invention, a biomass plastic film with high antibacterial properties can be obtained.

[0085] [Test Example 2] Surface quality and strength test The films of the present invention (Examples 6 to 13) obtained in (3-1) above were subjected to a tensile test according to the test method of JIS Z1702 and a tear strength test according to JIS K7128-2 (Emmendorf tear method). Particularly excellent measurement results are shown in Table 2 below. Samples that showed particularly excellent film properties or moldability are also shown in Table 2 below.

[0086] The equipment and measurement conditions used in the test are as follows: <Tensile test> Equipment used: Shimadzu AUTOGRAPH AG-500B AG-I / R - Test piece shape: Dumbbell Chuck spacing: 80mm Pulling speed: 500mm / min Load cell used: 5kgf Test environment: 20℃, humidity 65%Rh <Tear strength test> Equipment used: TEXTEST tear tester FX3700 Test environment: 20℃, humidity 65%Rh

[0087] [Table 2]

[0088] As is clear from Table 2, Examples 7, 8, and 10 to 12 exhibited excellent film strength. Among them, Examples 8 and 10 to 12 exhibited excellent surface smoothness and moldability, and Example 12 in particular was also excellent in transparency. [Industrial Applicability]

[0089] INDUSTRIAL APPLICABILITY The film of the present invention can provide resin molded articles and resin products that are excellent in carbon neutrality and antibacterial properties. The present invention is widely useful in many industries that use resins.

Claims

1. A biomass plastic film, characterized in that it is obtained by molding and stretching a resin composition containing wheat flour and / or wheat bran, a polyolefin resin, and a compatibilizer.

2. The biomass plastic film according to claim 1 , wherein the molding involving stretching is inflation molding.

3. The biomass plastic film according to claim 1 , further comprising a chelating agent.

4. The biomass plastic film according to claim 3 , wherein the chelating agent is an alkali metal salt of ethylenediaminetetraacetic acid or phytic acid.

5. The biomass plastic film according to claim 1 , further comprising a dehydrating agent.

6. The biomass plastic film according to claim 5 , wherein the dehydrating agent is one or more selected from calcium oxide, magnesium oxide, and burnt dolomite.

7. A bag-shaped product made of the biomass plastic film according to any one of claims 1 to 6.

8. A method for producing a biomass plastic film, comprising: a composition production step in which a raw material composition containing wheat flour and / or wheat bran, a polyolefin-based resin, and a compatibilizer is kneaded in the presence of water while releasing water vapor at a temperature at which the polyolefin-based resin undergoes thermal flow, and then cooled to below the thermal flow temperature to solidify, thereby obtaining a resin composition; and a stretching step in which a thermoplastic composition containing the resin composition is extruded under thermal flow, and shaped by stretching.

9. The method according to claim 8, wherein the amount of water in the composition production step is within the range of 10 to 40% by weight based on the dry weight of the wheat starch and / or wheat bran to be mixed, and the water content in the thermoplastic composition before molding in the stretching step is 0.5% by weight or less.

10. The method according to claim 8 or 9, wherein the molding in the stretching step is inflation molding.

11. The method according to claim 8 or 9, further comprising blending a chelating agent as a raw material in the composition production step.

12. The method of claim 11, wherein the chelating agent is an alkali metal salt of ethylenediaminetetraacetic acid or phytic acid.

13. The method according to claim 8 or 9, wherein in the stretching step, a dehydrating agent is mixed with the plastic composition before the molding involving the stretching.

14. The method according to claim 13, wherein the dehydrating agent is one or more selected from calcium oxide, magnesium oxide, and burnt dolomite.

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