Method for manufacturing starch-non-leaching film and molded article

Abstract

To provide a film that has a small elution amount of starch to water though containing the starch as a biomass material, and enables primary packaging of a food product.SOLUTION: A starch non-elutable film is formed of a thermoplastic resin containing starch. The starch non-elutability of the film is non-elutability determined by a potassium permanganate consumption test for evaluating elutability of starch contained in the film to water. The starch is plasticized starch. The starch is corn starch and / or tapioca starch.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a starch-non-eluting film and a molded article. [Background technology]

[0002] Conventionally, various films have been developed as packaging materials for various items such as food, pharmaceuticals, cosmetics, and hygiene products. Conventional films are made from petroleum-based materials, making them difficult to decompose in the natural environment after disposal, thus contributing to environmental pollution. In recent years, materials that decompose in the natural environment after disposal have been investigated, and films containing biomass materials have attracted attention as such materials. Because these films contain biomass materials as a substitute for petroleum-based materials, they can reduce CO2 emissions during combustion. Examples of biomass materials include waste biomass (food waste, livestock excrement, construction waste, and waste paper, etc.), unused biomass (non-edible parts of agricultural products and forest residues, etc.), and resource grains. More specific examples of biomass materials include wood flour, rice straw, bamboo, and old rice.

[0003] As a biomass material, starch that is naturally abundant and inexpensive is used. Starch is a so-called carbon-neutral material that, based on the amount of carbon dioxide emitted during combustion, is equal to the amount of carbon dioxide absorbed by the original plant (starch) during its growth process. However, starch itself is a high-molecular-weight material and lacks fluidity during molding and has difficulties in molding processability as it is, so starch with imparted plasticity is used by various methods. Regarding a plastic molded body containing starch, for example, in Patent Document 1 below, an article containing a polymer content, which includes a starch-based polymer material containing a first starch and a second starch and a polyolefin-based polymer material, is disclosed, where the amount of the polymer content that biodegrades after 91 days is more than the amounts of the first starch and the second starch based on the results of a biomethane potential test conducted at a temperature of about 52 °C using an inoculum having about 55 wt% water and about 45 wt% organic solids.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A film used for primary packaging of food is required to have a low elution amount of organic substances and the like contained in the film into water. However, when forming a film using starch as a biomass material, the elution amounts of starch and plasticizer contained in the film into water are large, and it has been difficult to provide a film capable of primary packaging of food. An object of the present technology is to provide a starch non-eluting film that has a low elution amount of starch into water and is capable of primary packaging of food, even though it contains starch as a biomass material.

Means for Solving the Problems

[0006] This technology provides a starch-non-eluting film formed from a thermoplastic resin containing starch. The starch non-leaching property of the aforementioned starch non-leaching film may be determined by a potassium permanganate consumption test, which evaluates the leaching of starch contained in the film into water. The aforementioned starch may be plasticized starch. The starch may be corn starch and / or tapioca starch. The aforementioned thermoplastic resin has an SP value of 7.8 (cal / cm). 1 / 2 More than 11.0 (cal / cm) 1 / 2 It may include the following first resin B1. The first resin B1 may be an ethylene-vinyl acetate copolymer (EVA). The aforementioned thermoplastic resin has an SP value of 7.7 (cal / cm). 1 / 2 More than 8.4 (cal / cm) 1 / 2 It may include the following second resin B2. The second resin B2 may be polyethylene resin. The SP value of the first resin B1 and the SP value of the second resin B2 may satisfy the following relationship. ΔSP B2W =|SP value of the second resin B2 -23.4 (cal / cm) 1 / 2 |>ΔSP B1W =|SP value of First Resin B1 - 23.4 (cal / cm) 1 / 2 | The thermoplastic resin may contain a compatibilizer. The aforementioned compatibilizer may be a carboxylic acid-modified polyolefin. The aforementioned starch-non-leaching film may be used for food packaging. The thermoplastic resin may be a biodegradable resin. This technology provides a method for producing a molded article, comprising: a starch-containing first resin preparation step of mixing starch and a first resin B1 to obtain a starch-containing first resin; a starch-containing resin composition preparation step of mixing the starch-containing first resin and a second resin B2 to obtain a starch-containing resin composition; and a molded article forming step of molding the starch-containing resin composition to obtain a molded article, wherein the molded article is starch-non-eluting. The molded body can be a film. The second resin B2 can be a resin different from the first resin B1. The second resin B2 can be the same resin as the first resin B1. The SP value of the first resin B1 can be 7.8 (cal / cm) 1 / 2 or more and 11.0 (cal / cm) 1 / 2 or less. The SP value of the second resin can be 7.7 (cal / cm) 1 / 2 or more and 8.4 (cal / cm) 1 / 2 or less. The SP value of the first resin B1 and the SP value of the second resin B2 can satisfy the following relational expression. ΔSP B2W = |SP value of the second resin B2 - 23.4 (cal / cm) 1 / 2 | > ΔSP B1W = |SP value of the first resin B1 - 23.4 (cal / cm) 1 / 2 | In the step of preparing the starch-containing first resin, 30 parts by mass or more of the first resin B1 can be blended with respect to 100 parts by mass of the starch. In the step of preparing the starch-containing resin composition, 60 parts by mass or more of the second resin B2 can be blended with respect to 100 parts by mass of the starch-containing first resin.

Advantages of the Invention

[0007] According to the present technology, despite containing starch as a biomass material, it is possible to provide a starch non-eluting film with a small amount of starch eluted into water and capable of primary packaging of food.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present technology will be described in detail. Note that the embodiments described below show an example of typical embodiments of the present technology, and the present technology is not limited to only these embodiments.

[0009] The present technology will be described in the following order. 1. First Embodiment (Example of a Starch-Non-Leaving Film) (1) Film composition (2) Physical properties (3) Method of manufacturing film (4) Uses of film 2. Second Embodiment (Example of a Method for Manufacturing a Molded Article) (1) Method for manufacturing molded articles 3. Examples

[0010] 1. First Embodiment (Example of a Starch-Non-Leaving Film)

[0011] (1) Film composition The starch-non-leaching film according to the first embodiment is formed from a thermoplastic resin. The thermoplastic resin contains starch. The starch-non-leaching film according to the first embodiment exhibits starch-non-leaching properties.

[0012] The thermoplastic resin used to form the starch-non-eluting film according to the first embodiment will be described in more detail below.

[0013] [Thermoplastic resin]

[0014] The thermoplastic resin forming the starch-non-eluting film according to the first embodiment is preferably a polyolefin resin, a polyester resin, or a mixture thereof. The thermoplastic resin may also be a polystyrene resin.

[0015] Polyolefin resins are polymers obtained by polymerization using olefins (e.g., α-olefins) as the main monomers. These polyolefin resins may be, for example, polyethylene (PE) resin, polypropylene (PP) resin, or a combination of these resins.

[0016] The polyethylene resin may be, for example, low-density polyethylene (LDPE), high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA resin), or ultra-high molecular weight polyethylene (UHMW-PE), or a combination of these resins.

[0017] The polypropylene resin may be, for example, a homopolymer polypropylene resin, or a random copolymer or block copolymer polypropylene resin (e.g., an ethylene-propylene copolymer), or a combination of these resins.

[0018] The polyolefin resin may preferably be a biomass-derived polyolefin resin (for example, a biomass-derived polyethylene resin), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. This can reduce CO2 emissions.

[0019] The polyolefin resin may be a polyolefin resin produced using a metallocene catalyst. That is, the thermoplastic resin may be, for example, a metallocene catalyst-based polyethylene resin or polypropylene resin, or a combination of these resins.

[0020] The aforementioned polystyrene resin may also be a metallocene catalyst-based polystyrene resin.

[0021] Polyester resins are polymers formed by the polymerization of monomers via ester bonds. These polyester resins may include, for example, polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polylactic acid resin (PLA), or polycarbonate resin (PC), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), or a combination of two or more resins selected from these.

[0022] Polystyrene resins are polymers formed by the polymerization of styrene monomers. These polystyrene resins may include, for example, polystyrene resin, rubber-reinforced polystyrene resin (high-impact polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylic acid ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, and acrylonitrile-ethylene propylene-styrene copolymer, or any combination of two or more resins selected from these.

[0023] The type of thermoplastic resin used to form the starch-non-leaching film according to the first embodiment may be appropriately selected by those skilled in the art depending on the type of starch-non-leaching film formed from the thermoplastic resin, but a thermoplastic resin with a low processing temperature is preferred. For example, when forming a starch-non-leaching film from such a thermoplastic resin, the thermoplastic resin is preferably a polyolefin resin. Such a polyolefin resin may be a polyethylene resin or a polypropylene resin.

[0024] Furthermore, in order to suppress the elution of starch contained in the thermoplastic resin into water, the thermoplastic resin has an SP value of 7.8 (cal / cm). 1 / 2 More than 11.0 (cal / cm) 1 / 2The following primary resin B1 may preferably be included. The SP value can be calculated by Fedors' estimation method or the like. Examples of such primary resin B1 include polyethylene resin. For example, ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA resin) are preferred.

[0025] Furthermore, the thermoplastic resin has an SP value of 7.7 (cal / cm). 1 / 2 More than 8.4 (cal / cm) 1 / 2 The following secondary resin B2 may preferably be included. Examples of such secondary resin B2 include polyethylene resin. For example, low-density polyethylene resin (LDPE), high-density polyethylene resin (HDPE), very low-density polyethylene resin (VLDPE), linear low-density polyethylene resin (LLDPE), etc.

[0026] The first resin B1 and the second resin B2 may be the same type of resin, or they may be different types of resins.

[0027] More preferably, the SP value of the first resin B1 and the SP value of the second resin B2 may satisfy the following relationship. ΔSP B2W =|SP value of the second resin B2 -23.4 (cal / cm) 1 / 2 |>ΔSP B1W =|SP value of First Resin B1 - 23.4 (cal / cm) 1 / 2 |

[0028] As shown in the above relational expression, the SP value of the first resin B1 and the SP value of water are 23.4 (cal / cm). 1 / 2 The absolute value of the difference between the two is 23.4 (cal / cm²), which is the SP value of the second resin B2 and the SP value of water. 1 / 2It is preferable that the absolute value of the difference between the two is smaller. In other words, it is preferable that the first resin B1 is more hydrophilic than the second resin B2.

[0029] The thermoplastic resin used to form the starch-non-eluting film according to the first embodiment preferably has a melting point of 90°C to 180°C, and more preferably 95°C to 170°C. By using a thermoplastic resin with a lower melting point, the temperature during film molding can be lowered, and odor or discoloration caused by heating of the starch contained in the thermoplastic resin can be further suppressed.

[0030] The thermoplastic resin may be in pellet or powder form, and is mixed and kneaded during molding using an extruder or injection molding machine to ensure uniform dispersion.

[0031] In the starch-non-leaching film according to the first embodiment, the thermoplastic resin may be a biodegradable resin. Examples of biodegradable resins include biodegradable polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and polylactic acid (PLA), polybutylene succinate (PBS), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), as well as a mixture of two or more selected from the above biodegradable resins. In this embodiment, since both the thermoplastic resin and the starch are biodegradable, the starch-non-leaching film according to this embodiment can be more environmentally friendly.

[0032] The following describes in more detail the starch contained in the thermoplastic resin that forms the starch-non-eluting film according to the first embodiment.

[0033] [starch]

[0034] Examples of starches contained in the thermoplastic resin include underground starches and above-ground starches.

[0035] Underground starches are starches accumulated underground, such as those stored in rhizomes or roots. Examples of underground starches include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, kudzu starch, and bracken starch.

[0036] Ground-based starches are starches accumulated on the ground, such as those accumulated in seeds. Examples of ground-based starches include, but are not limited to, corn starch, wheat starch, sago starch, acorn starch, and rice starch.

[0037] The thermoplastic resin forming the starch-non-eluting film according to the first embodiment may preferably contain underground starch. By including underground starch in the thermoplastic resin, the odor of the thermoplastic resin can be further reduced.

[0038] The starch contained in the thermoplastic resin may be a modified starch (i.e., modified starch), particularly a modified underground starch. Examples of such modified starches include physically modified starch and chemically modified starch. Examples of physically modified starches include alpha starch and moist heat starch. Examples of chemically modified starches include acetoacetate esterified starch, acetate esterified starch, hydroxymethyl etherified starch, hydroxypropyl etherified starch, carboxymethyl etherified starch, allyl etherified starch, methyl etherified starch, succinate esterified starch, xanthogene acetate esterified starch, nitrate esterified starch, urea phosphate esterified starch, phosphate esterified starch, phosphate crosslinked starch, formaldehyde crosslinked starch, acrolein crosslinked starch, and epichlorohydrin crosslinked starch. Modified starches can be plasticized at lower temperatures compared to unmodified starch. Therefore, odors and / or discoloration associated with heating during the production of plasticized starch, as described later, can be suppressed.

[0039] The starch contained in the thermoplastic resin may preferably contain equilibrium moisture. The amount of equilibrium moisture may be, for example, preferably 10% to 15% by mass, more preferably 10% to 14% by mass, even more preferably 10% to 13% by mass, and even more preferably 11% to 13% by mass, relative to the mass of starch. From the viewpoint of plasticizing the starch, starch or modified starch containing equilibrium moisture within the above numerical range is preferred.

[0040] In the starch-non-eluting film according to the first embodiment, the thermoplastic resin may contain the starch and the thermoplastic resin in a ratio of, for example, preferably 5 parts by mass:95 parts by mass to 75 parts by mass:25 parts by mass, more preferably 10 parts by mass:90 parts by mass to 70 parts by mass:30 parts by mass, and even more preferably 15 parts by mass:75 parts by mass to 70 parts by mass:30 parts by mass. The thermoplastic resin having this ratio can reduce the size of the starch particles contained in the starch-non-eluting film.

[0041] The starch contained in the thermoplastic resin may be plasticized. Plasticization of the starch can reduce the particle size of the starch granules to 2 μm or less. This makes it possible to make the surface of the starch-non-leaching film formed from the thermoplastic resin smooth, and also improves the physical properties of the starch-non-leaching film (e.g., tensile elongation). Plasticization of starch can be achieved, for example, by heating the starch, or by contacting the starch with a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature and then heating it.

[0042] Furthermore, by using the plasticized starch (hereinafter referred to as "plasticized starch"), a starch-non-leaching film with good quality (e.g., surface smoothness, low coloration, and low odor) can be manufactured. For example, in the starch-non-leaching film according to the first embodiment, since the particle size of the starch granules contained in the thermoplastic resin is small, at 2 μm or less, even if a thin starch-non-leaching film is formed from the thermoplastic resin, the shape of the starch granules does not appear on the surface. For example, in the starch-non-leaching film according to the first embodiment, even if the starch content in the thermoplastic resin is increased, the starch-non-leaching film formed from the thermoplastic resin does not have the shape of starch granules on its surface.

[0043] Furthermore, by including the plasticized starch in the thermoplastic resin, transparency can be imparted to the thermoplastic resin and the starch-non-leaching film formed from the thermoplastic resin. In addition, by including the plasticized starch in the thermoplastic resin, the surface of the thermoplastic resin and the starch-non-leaching film formed from the thermoplastic resin can be made smooth.

[0044] In the thermoplastic resin, the content of the plasticized starch may be, for example, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to the mass of the thermoplastic resin.

[0045] In the starch-non-eluting film according to the first embodiment, the plasticized starch may be a plasticized starch or a plasticized modified starch. For example, the starch may be corn starch or tapioca starch.

[0046] The plasticized starch may more preferably be a plasticized starch product of one or more starches selected from tapioca starch (cassava starch), potato starch, sweet potato starch, kudzu starch, and bracken starch, or a modified plasticized starch product of one or more modified starches. Even more preferably, the plasticized starch is a plasticized tapioca starch product or a modified plasticized tapioca starch product. These plasticized products are particularly preferred from the viewpoint of reducing the odor of the plasticized starch and the odor of the thermoplastic resin.

[0047] By incorporating the plasticized starch into the thermoplastic resin, excellent moldability can be achieved when producing a starch-non-leaching film from the thermoplastic resin. Furthermore, the physical properties of the starch-non-leaching film can be improved. For example, if the content of starch (e.g., ungelatinized starch) in the thermoplastic resin is 50% by mass or more, molding using the thermoplastic resin may not be possible, or even if molding is possible, the molded starch-non-leaching film may not have good quality. Specifically, when inflation molding is performed using a thermoplastic resin, the thermoplastic resin may not expand, or foaming may occur within the thermoplastic resin. Moreover, even if it expands, the starch-non-leaching film obtained by such molding may have poor elasticity, making it easily torn and lacking in excellent strength.

[0048] The plasticized starch may be directly incorporated into the thermoplastic resin. Alternatively, it may be incorporated into the thermoplastic resin as a plasticized starch material comprising starch and a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature.

[0049] The following describes plasticized starch materials.

[0050] <Plasticized starch material>

[0051] The plasticized starch material may be a material mainly composed of starch. The starch content in the plasticized starch material may be, for example, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, relative to the mass of the plasticized starch material. The starch content in the plasticized starch material may be, for example, preferably 99.5% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less, relative to the mass of the plasticized starch material. The starch content may be measured by TG measurement (thermogravimetric analysis) at 150°C. Specifically, the content may be determined based on the amount of mass change measured using a TG measuring device (STA7200, Hitachi High-Tech Science Corporation). The amount of mass change corresponds to the amount of decrease in volatile components, and the amount of decrease corresponds to the amount of polar organic compounds that can gelatinize or plasticize the starch. Therefore, the starch content in the plasticized starch material can be calculated using the following formula: (Starch content in the plasticized starch material (unit: mass%)) = (Mass after the start of measurement of the mass change) / (Mass before the start of measurement of the mass change) × 100. The measurement conditions for the mass change are as follows: Temperature range 25°C to 150°C, heating rate 20°C / min, under nitrogen.

[0052] In this specification, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature means a polar organic compound that can gelatinize or plasticize starch by contacting it at a temperature higher than room temperature. Organic compounds known in the art may be used as the polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature.

[0053] A polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature refers to a polar organic compound that is not capable of gelatinizing or plasticizing starch at room temperature but is capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. In this specification, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature is also referred to as a "polar organic compound capable of gelatinizing or plasticizing starch at high temperature." For example, if starch does not gelatinize or plasticize when a polar organic compound is brought into contact with starch at room temperature for one hour, but the starch does gelatinize or plasticize when the polar organic compound is brought into contact with starch at a high temperature for one hour, then the polar organic compound is "capable of gelatinizing or plasticizing starch at high temperature." The polar organic compound capable of gelatinizing or plasticizing starch may be any of the following: a polar organic compound capable of gelatinizing starch, a polar organic compound capable of plasticizing starch, or a polar organic compound capable of both gelatinizing and plasticizing starch.

[0054] In this specification, a temperature higher than room temperature (also referred to as "high temperature") refers to a temperature achieved by heat treatment. High temperature may be, for example, 50°C or higher, preferably 60°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher.

[0055] In this specification, room temperature refers to the temperature when no heat treatment is performed. Room temperature may be, for example, less than 50°C, preferably 10 to 40°C, more preferably 15 to 35°C, and even more preferably 20 to 30°C.

[0056] Preferably, the total content of polar organic compounds in the plasticized starch material that can gelatinize or plasticize the starch at temperatures higher than room temperature is, for example, preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less, relative to the mass of the plasticized starch material. The total content of polar organic compounds in the plasticized starch material that can gelatinize or plasticize the starch at temperatures higher than room temperature is, for example, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, relative to the mass of the plasticized starch material. The total content of polar organic compounds that can gelatinize or plasticize the starch at temperatures higher than room temperature is calculated by subtracting the content of gelatinized starch measured by the TG measurement described above from 100% by mass.

[0057] A polar organic compound capable of gelatinizing or plasticizing starch at temperatures higher than room temperature is preferably a liquid at room temperature. This facilitates mixing with starch.

[0058] The polar organic compound constituting the plasticized starch material, which can gelatinize or plasticize starch at temperatures higher than room temperature (high temperature), may contain at least one polyhydric alcohol.

[0059] A polyhydric alcohol is an alcohol having two or more hydroxyl groups in its molecule. Such a polyhydric alcohol is preferably a polyhydric alcohol having 2 to 5 carbon atoms, and more preferably a polyhydric alcohol having 2 to 4 carbon atoms. The said polyhydric alcohol preferably has 2 to 5 hydroxyl groups (OH groups), and more preferably has 2 to 4 hydroxyl groups (OH groups).

[0060] The aforementioned polyhydric alcohol may include, for example, glycerin and glycol. Examples of such glycols include ethylene glycol and propylene glycol.

[0061] The polyhydric alcohol may preferably comprise one or more combinations selected from glycerin, ethylene glycol, and propylene glycol. The plasticized starch material may contain, for example, preferably 10 to 40 parts by mass, and more preferably 20 to 35 parts by mass, of the polyhydric alcohol per 100 parts by mass of starch. Furthermore, the content of the polyhydric alcohol in the starch-non-eluting film may preferably be 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more.

[0062] From the viewpoint of suppressing bleed occurrence under high temperature and high humidity conditions, the glycerin content in the starch-non-eluting film is preferably 0% to 10% by mass, more preferably 0% to 9% by mass, and even more preferably 0% to 7% by mass. The lower the amount of glycerin, the more effectively bleed occurrence can be suppressed. Therefore, it is preferable to use other polyhydric alcohols instead of glycerin, for example, ethylene glycol or propylene glycol are preferred as substitutes for glycerin. In other words, from the viewpoint of suppressing bleed occurrence, it is also possible to omit glycerin altogether and, for example, contain only ethylene glycol or only propylene glycol.

[0063] However, the starch granules may become larger as the glycerin content decreases. To reduce the size of the starch granules even when the glycerin content is reduced, the plasticized starch material may further contain organic acids. An organic acid is an organic compound that exhibits acidity, and an organic compound is a compound having at least one carbon atom. Examples of organic acids include carboxylic acids, sulfonic acids, sulfinic acids, organic phosphinic acids, and organic phosphonic acids.

[0064] Examples of the carboxylic acids mentioned above include monocarboxylic acids such as lactic acid, gluconic acid, acetic acid, and acetic anhydride; dicarboxylic acids such as tartaric acid, maleic acid, maleic anhydride, adipic acid, succinic acid, succinic anhydride, and malic acid; and carboxylic acids having three or more carboxyl groups, such as citric acid. Examples of the sulfonic acids mentioned above include benzenesulfonic acid and methanesulfonic acid. Examples of the sulfinic acids mentioned above include benzenesulfinic acid and cysteine ​​sulfonic acid. Examples of the organic phosphinic acids mentioned above include diethylphosphinic acid. Examples of the organic phosphonic acids mentioned above include methylphosphonic acid.

[0065] The aforementioned plasticized starch material may contain a polyhydric alcohol. This polyhydric alcohol may be, for example, a combination of glycerin and ethylene glycol, or ethylene glycol alone. In the case of ethylene glycol alone, it may also contain an organic acid.

[0066] The aforementioned plasticized starch material can be gelatinized or plasticized by heating it at a temperature higher than room temperature in the presence of a polar organic compound capable of gelatinizing or plasticizing the starch. This gelatinization or plasticization may be brought about, for example, by the cleavage of intermolecular bonds (mainly hydrogen bonds) by heating in the presence of a polar organic compound capable of gelatinizing or plasticizing at high temperatures. The gelatinized or plasticized starch may be, for example, pregelatinized starch. This plasticization is thought to contribute to imparting transparency and / or smoothness to the starch-non-eluting film.

[0067] [Other ingredients]

[0068] The thermoplastic resin forming the starch-non-eluting film according to the first embodiment may contain other components in addition to the starch and the thermoplastic resin. Examples of such other components include compatibilizers, oxidative decomposition accelerators, colorants, antioxidants, and cellulose nanofibers.

[0069] The compatibilizer may be used to further improve the compatibility between the plasticized starch and the thermoplastic resin when the starch is a plasticized starch.

[0070] Examples of the compatibilizers include carboxylic acid anhydride-modified polyolefins, olefin-based graft-modified products, and olefin-based comonomers.

[0071] The carboxylic acid anhydride constituting the carboxylic acid anhydride-modified polyolefin is preferably maleic anhydride. The compatibilizer may be one or more selected from the group consisting of maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer.

[0072] The olefin-based graft-modified product may be an acid-modified polyolefin, and more specifically, a polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. The (unmodified) polyolefin used for graft modification may be, for example, polyethylene, polypropylene, or ethylene-α-olefin copolymer (ethylene-propylene copolymer), and may be particularly polypropylene. For example, the acid-modified polyolefin described in Japanese Patent Application Publication No. 2010-095671 may be used.

[0073] The aforementioned oxidative decomposition accelerator may be a combination of a carboxylate metal salt and a rare earth compound. An example of an oxidative decomposition accelerator containing such a combination is P-Life (manufactured by P-Life Japan Inc.).

[0074] The carboxylate metal salt contained in the oxidative decomposition accelerator may be, for example, a metal salt of an aliphatic carboxylic acid having 10 to 20 carbon atoms, and more preferably a metal stearate salt. The metal atom that forms the metal salt with the aliphatic carboxylic acid may be one or more combinations selected from, for example, cobalt, cerium, iron, aluminum, antimony, barium, bismuth, chromium, copper, gallium, lanthanum, lithium, magnesium, molybdenum, nickel, calcium, silver, sodium, tin, tungsten, vanadium, yttrium, zinc, and zirconium, and more preferably one or more combinations selected from calcium, magnesium, zinc, cobalt, cerium, iron, and copper. For example, the metal salt may be iron stearate. As the carboxylate salt, one type of carboxylate salt may be used alone, or a combination of two or more types of carboxylate salts may be used.

[0075] The rare earth compound contained in the oxidative decomposition accelerator may be, for example, a rare earth oxide, a rare earth hydroxide, a rare earth sulfate, a rare earth nitrate, a rare earth acetate, a rare earth chloride, or a rare earth carboxylate. More specifically, the rare earth compound may be one or more selected from cerium oxide, ceric sulfate, ceric ammonium sulfate, ceric ammonium nitrate, cerium acetate, lanthanum nitrate, cerium chloride, cerium nitrate, cerium hydroxide, cerium octolate, lanthanum oxide, yttrium oxide, and scandium oxide. The rare earth compound may be used alone or in combination of two or more rare earth compounds.

[0076] Examples of the coloring agent include titanium dioxide and / or carbon black. Examples of the antioxidant include, but are not limited to, phenolic antioxidants.

[0077] The cellulose nanofibers (hereinafter also referred to as CNF) may be commercially available CNF. Unlike molecular cellulose, CNF may refer to fibrous cellulose with an average fiber diameter of 10 nm to 3000 nm, which is poorly soluble in solvents. The average fiber diameter is preferably 10 nm to 1000 nm, more preferably 10 nm to 500 nm, even more preferably 10 nm to 300 nm, and even more preferably 10 nm to 100 nm. The aspect ratio of the CNF may be, for example, preferably 30 to 10000, more preferably 50 to 5000, and even more preferably 50 to 1000. The aspect ratio is a value obtained by dividing the average fiber length by the average fiber diameter. The above average fiber length and average fiber diameter are the average values ​​of 10 arbitrary cellulose fibers observed with an electron microscope.

[0078] CNF is hydrophilic. CNF is generally produced by dissolving cellulose material in water to create nanoparticles, and therefore is dispersed in water.

[0079] CNF is used, for example, to increase the strength of thermoplastic resins. However, since thermoplastic resins are often hydrophobic, mixing hydrophilic CNF with thermoplastic resins can be difficult. Therefore, for example, hydrophobized CNF (especially powdered CNF) is mixed with thermoplastic resins. For this hydrophobization, the TENPO oxidation method can be used. Alternatively, a CNF dispersion obtained by solvent replacement of water in which CNF is dispersed is mixed with a liquid resin (e.g., epoxy resin or vinyl chloride resin). Another method involves directly crushing the cellulose material in an extruder without crushing it with water, and then mixing the resulting CNF with the thermoplastic resin. Such mixing methods can be costly (e.g., labor, expenses, or time). Therefore, a method that uses CNF dispersed in water as is is preferable.

[0080] Furthermore, as mentioned above, dispersing CNF in thermoplastic resin is difficult. If dispersion is poor, only one of the following can be improved: the tensile elongation or the tensile strength of the resulting CNF-containing thermoplastic resin.

[0081] Furthermore, CNF is generally found dispersed in water; for example, the CNF content in a CNF aqueous dispersion is only a few mass percent, meaning that CNF aqueous dispersions have a high water content. Therefore, mixing CNF aqueous dispersions with thermoplastic resins is often difficult.

[0082] The plasticized starch material can easily disperse CNF within it, and furthermore, the plasticized starch material containing CNF can be easily mixed with a thermoplastic resin. Therefore, the plasticized starch material allows for easy dispersion of CNF in the thermoplastic resin. By including CNF in the thermoplastic resin, the tensile properties and impact strength of the starch-non-leaching film molded from the thermoplastic resin can be improved. In the embodiment in which the plasticized starch material contains CNF, CNF may also be added to the thermoplastic resin.

[0083] As the CNF, CNF dispersed in water can be used. Even when using an aqueous dispersion of CNF, by using the aqueous dispersion of CNF in the production of the plasticized starch material, the CNF can be easily dispersed in the thermoplastic resin without using the mixing method described above.

[0084] Furthermore, when the plasticized starch material containing CNF is mixed with a thermoplastic resin, the CNF disperses well within the thermoplastic resin. Therefore, both the tensile elongation and tensile strength of the thermoplastic resin can be improved.

[0085] Furthermore, an increase in the biomass content or biodegradable resin content in a thermoplastic resin can lead to a decrease in its tensile strength. As described above, mixing the plasticized starch material containing CNF with the thermoplastic resin can resolve the problem of decreased tensile strength caused by a high biomass content or biodegradable resin content in the thermoplastic resin. In addition, other effects brought about by CNF may also manifest in the thermoplastic resin.

[0086] Examples of CNF contained in the plasticized starch material include CNF dispersed in water produced by the general manufacturing method described above. In addition to the CNF dispersed in water, modified CNF such as the hydrophobic CNF described above may also be included in the plasticized starch material. Powdered CNF can also be dispersed in the plasticized starch material if it is dispersed in water. In this way, the plasticized starch material can disperse various types of CNF. CNF dispersed in water is preferred as the CNF dispersed in the plasticized starch material from the viewpoint of cost and ease of handling. CNF dispersed in water is also particularly easy to input into the manufacturing equipment for the plasticized starch material.

[0087] Furthermore, CNF dispersed in a hydrophilic liquid other than water may be used. The CNF dispersed in the plasticized starch material may be dispersed in one hydrophilic liquid or in a mixture of two or more hydrophilic liquids. That is, the liquid in which the CNF dispersed in the plasticized starch material is dispersed may be one or more combinations selected from water, glycerin, ethylene glycol, propylene glycol, formamide, and urea solution. The liquid may also be one or more combinations of the polyhydric alcohols mentioned above.

[0088] The thermoplastic resin forming the starch-non-eluting film according to the first embodiment may preferably comprise the starch, the thermoplastic resin, the compatibilizer, and the oxidative decomposition accelerator. The composition ratio of the starch and the thermoplastic resin may, for example, preferably be 20 parts by mass:80 parts by mass to 80 parts by mass:20 parts by mass, more preferably 30 parts by mass:70 parts by mass to 80 parts by mass:20 parts by mass, and even more preferably 50 parts by mass:50 parts by mass to 80 parts by mass:20 parts by mass. The content of the compatibilizer may, for example, preferably be 1 to 10 parts by mass, and more preferably 2 to 9 parts by mass, based on 100 parts by mass of the total amount of the starch and the thermoplastic resin. The content of the oxidative decomposition accelerator may, for example, preferably be 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the total amount of the starch and the thermoplastic resin.

[0089] (2) Physical properties

[0090] [Starch non-leaching]

[0091] The starch-non-leaching film according to the first embodiment exhibits starch non-leaching properties. Here, starch non-leaching means the property that the starch contained in the thermoplastic resin does not dissolve in water. In this embodiment, starch non-leaching may preferably mean non-leaching as determined by a potassium permanganate consumption test.

[0092] <Potassium permanganate consumption test> Potassium permanganate consumption refers to the amount of potassium permanganate required to oxidize the amount of organic matter and reducing substances (oxidizable substances) in water under predetermined conditions. In the starch-non-eluting film according to the first embodiment, the amount of potassium permanganate required to oxidize the amount of starch eluted into water under predetermined conditions is expressed as the potassium permanganate consumption, and the starch-non-eluting property can be evaluated.

[0093] In the starch-non-eluting film according to the first embodiment, the starch-non-eluting property can be evaluated by a potassium permanganate consumption test through the following steps. (i) Cut the film into 5cm squares and wash both sides thoroughly with pure water. (ii) Put 100 mL of distilled water into a beaker and heat the beaker in a 60°C water bath. (iii) Immerse the washed film in a beaker of pure water heated in a 60°C water bath and leave for 30 minutes. The liquid in the beaker will be used as the eluent. (iv) After 30 minutes, remove the film and filter the eluate through filter paper. The mesh size of the filter paper is arbitrary. The filtered liquid is the filtrate. (v) Add 5 mL of commercially available sulfuric acid diluted 3 times and 10 mL of 0.002 mol / L potassium permanganate solution to the filtrate and boil for 5 minutes. (vi) Stop heating and immediately compare the color difference with the blank that has gone through steps (i) to (v) above, except that the film is not immersed in the pure water in the beaker in step (ii) above. Furthermore, non-elution properties will be evaluated according to the following criteria. A: There is no color difference from the blank. B: Some color remains, but it is lighter than the blank. C: Becomes colorless.

[0094] (3) Method of manufacturing film

[0095] The method for producing a starch-non-eluting film according to the first embodiment can employ a conventional method for producing petroleum-based plastic films. For example, it may include a first mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water; a plasticized starch preparation step of preparing plasticized starch by heating the mixture obtained in the first mixing step to plasticize the starch; and a starch-containing first resin preparation step of preparing a starch-containing first resin by kneading the plasticized starch with a thermoplastic resin used as a first resin (hereinafter sometimes referred to as the first resin). The production method may also include a starch-containing resin composition preparation step of further kneading the starch-containing first resin obtained in the starch-containing first resin preparation step with a thermoplastic resin used as a second resin (hereinafter sometimes referred to as the second resin) to prepare a starch-containing resin composition. Furthermore, the production method may include a molding step of molding the starch-containing resin composition obtained in the starch-containing resin composition preparation step.

[0096] Furthermore, in the starch-containing first resin preparation step, for example, starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, water, and raw materials such as a thermoplastic resin may be mixed first. The first resin may be supplied in pellet form or in powder form. The mixing of the raw materials such as starch and thermoplastic resin may be carried out, for example, by a commercially available stirrer or a mixer such as a Henschel mixer, tumbler mixer, Barber mixer, or kneader mixer. It is preferable that the mixing of the raw materials be carried out at room temperature. Alternatively, after mixing the raw materials at room temperature, the mixed raw materials may naturally generate heat to about 40°C. The kneading of the mixed raw materials may be carried out, for example, by a single-screw kneading extruder or a twin-screw kneading extruder. As these kneading extruders, devices known in the art may be used. Preferably, the starch-containing first resin preparation step includes at least a kneading process using a twin-screw kneading extruder. As the twin-screw compounding extruder, a twin-screw compounding extruder with co-rotation in both directions may be used, or a twin-screw compounding extruder with opposite rotation in both directions may be used. By performing the compounding process with a twin-screw compounding extruder, a starch-containing primary resin in which the starch is more uniformly dispersed can be obtained.

[0097] The starch-containing first resin preparation step may involve heating the first resin to a temperature at which it can melt. This temperature may be appropriately selected by those skilled in the art depending on the melting point of the first resin used. The kneading in this step may be carried out preferably at 80 to 200°C, more preferably at 90 to 170°C, and even more preferably at 95 to 180°C. The kneading time may be appropriately set.

[0098] In the starch-containing first resin preparation step, the starch-containing first resin may be subjected to the molding step as is, without being pelletized. This eliminates the need for the pelletizing step.

[0099] In addition, in the starch-containing first resin preparation step, the starch-containing first resin may be prepared by mixing starch and the first resin in a mixer, then extruding the strand using a single-screw or twin-screw extruder, cutting it to produce pellets, and using these pellets as a masterbatch in the molding step.

[0100] In the starch-containing first resin preparation step, preferably 30 parts by mass or more of the first resin is blended with 100 parts by mass of the starch, more preferably 40 parts by mass or more of the first resin, even more preferably 50 parts by mass or more of the first resin, and even more preferably 60 parts by mass or more of the first resin.

[0101] In the starch-containing first resin preparation step, the first resin may be blended in a quantity of 95 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less, per 100 parts by mass of starch.

[0102] In the starch-containing first resin preparation step, other components may be added in addition to the starch and the first resin. Examples of such other components include the compatibilizer, the oxidative decomposition accelerator, the coloring agent, and the antioxidant.

[0103] In the starch-containing resin composition preparation step, the thermoplastic resin corresponding to the second resin may be supplied in pellet form or in powder form. The kneading of the starch-containing first resin and the second resin may be carried out, for example, by a single-screw kneading extruder or a twin-screw kneading extruder. As these kneading extruders, devices known in the art may be used. Preferably, the starch-containing resin composition preparation step includes at least a kneading process using a twin-screw kneading extruder. As the twin-screw kneading extruder, a twin-screw kneading extruder that rotates in the same direction may be used, or a twin-screw kneading extruder that rotates in opposite directions may be used. By performing the kneading process using a twin-screw kneading extruder, a starch-containing resin composition in which the starch is more uniformly dispersed can be obtained.

[0104] In the starch-containing resin composition preparation step, the second resin may be heated to a temperature at which it can melt. This temperature may be appropriately selected by those skilled in the art depending on the melting point of the second resin used. The kneading in this step is preferably carried out at 80 to 200°C, more preferably at 90 to 170°C, and even more preferably at 95 to 180°C. The kneading time may be appropriately set.

[0105] In the starch-containing resin composition preparation step, the starch-containing resin composition may be subjected to the molding step as is, without being pelletized. This eliminates the need for the pelletizing step.

[0106] Furthermore, the starch-containing resin composition obtained in the starch-containing resin composition preparation step may be prepared by supplying the first starch-containing resin and the second resin to a single-screw or twin-screw extruder, extruding strands from these extruders, cutting them to produce pellets, and using these pellets as a masterbatch in the molding process.

[0107] In the starch-containing resin composition preparation step, preferably 60 parts by mass or more of the second resin is blended with 100 parts by mass of the starch-containing first resin, more preferably 70 parts by mass or more of the second resin, even more preferably 80 parts by mass or more of the second resin, and even more preferably 90 parts by mass or more of the second resin.

[0108] In the starch-containing resin composition preparation step, a second resin may be blended in an amount of 170 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less, with respect to 100 parts by mass of the first starch-containing resin.

[0109] In the starch-containing resin composition preparation step, other components may be added in addition to the first starch-containing resin and the second resin. Examples of such other components include the compatibilizer, the oxidative decomposition accelerator, the colorant, and the antioxidant.

[0110] In the molding process, for example, the starch-containing resin composition may be molded into a film using an inflation molding machine.

[0111] When manufacturing the film, the molding temperature range is preferably 95 to 200°C when the raw materials are directly mixed and kneaded for molding, from the viewpoint of suppressing burning and decomposition of the raw materials and seizing inside the cylinder, and from the viewpoint of suppressing the discharge of starch in an unmelted state, which can cause problems as the pressure rises. When manufacturing pellets and then molding, the range is also preferably 95 to 200°C.

[0112] Furthermore, from the viewpoint of preventing burning and decomposition of the raw materials, it is preferable that the residence time in the cylinder be no more than 10 minutes.

[0113] The film extruded by the inflation molding machine may be cooled, taken up, and wound up after the take-up roll temperature is set to 90°C or lower, once it has been formed to a predetermined thickness.

[0114] The starch-non-eluting film according to this embodiment may be coated with a film on the main surface of the film. The main surface coated with the film may be one side or both sides of the film. Such a film may be, for example, a polyolefin resin such as polyethylene (PE resin), polypropylene (PP) resin, or a combination of two or more selected from these. Alternatively, it may be a polyester resin such as polylactic acid resin (PLA), polycarbonate resin (PC), polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), or a combination of two or more selected from these. An adhesive layer may be provided between the film or sheet and the film. As such an adhesive layer, a resin having a melting point lower than the melting point of the resin composition forming the film or sheet may be used. Examples of resins used in such adhesive layers include epoxy resins and urethane resins. The starch-non-eluting film and the aforementioned film can be bonded together via heat sealing or an adhesive layer.

[0115] (4) Uses of film

[0116] The starch-non-leaching film according to this embodiment can be used, for example, as a food packaging film, food packaging bag, shopping bag, garbage collection bag, or agricultural bag.

[0117] 2. Second Embodiment (Example of a Method for Manufacturing a Molded Article)

[0118] (1) Method for manufacturing molded articles The method for manufacturing a molded article according to the second embodiment includes a starch-containing first resin preparation step of mixing starch and a first resin B1 to obtain a starch-containing first resin, a starch-containing resin composition preparation step of mixing the starch-containing first resin and a second resin B2 to obtain a starch-containing resin composition, and a molded article forming step of molding the starch-containing resin composition to obtain a starch-non-eluting molded article.

[0119] [Starch-containing first resin preparation process]

[0120] In the first resin preparation step containing starch, starch and the first resin B1 are mixed.

[0121] The following describes the starch used in this process.

[0122] <Starch>

[0123] Examples of starches used in this process include underground starches and above-ground starches.

[0124] Underground starches are starches accumulated underground, such as those stored in rhizomes or roots. Examples of underground starches include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, kudzu starch, and bracken starch.

[0125] Ground-based starches are starches accumulated on the ground, such as those accumulated in seeds. Examples of ground-based starches include, but are not limited to, corn starch, wheat starch, sago starch, acorn starch, and rice starch.

[0126] In this process, underground starch may preferably be used. By mixing underground starch with the first resin, the odor of the first resin can be further reduced.

[0127] The starch may be a modified starch (i.e., modified starch), particularly a modified underground starch. Examples of such modified starches include physically modified starch and chemically modified starch. Examples of physically modified starches include alpha starch and moist heat starch. Examples of chemically modified starches include acetoacetate esterified starch, acetate esterified starch, hydroxymethyl etherified starch, hydroxypropyl etherified starch, carboxymethyl etherified starch, allyl etherified starch, methyl etherified starch, succinate esterified starch, xanthogene acetate esterified starch, nitrate esterified starch, urea phosphate esterified starch, phosphate esterified starch, phosphate cross-linked starch, formaldehyde cross-linked starch, acrolein cross-linked starch, and epichlorohydrin cross-linked starch. Modified starches can be plasticized at lower temperatures compared to unmodified starch. Therefore, odors and / or discoloration associated with heating during the production of plasticizable starch, as described later, can be suppressed.

[0128] The starch may preferably contain equilibrium moisture. The amount of equilibrium moisture may be, for example, preferably 10% to 15% by mass, more preferably 10% to 14% by mass, even more preferably 10% to 13% by mass, and even more preferably 11% to 13% by mass, relative to the mass of starch. From the viewpoint of plasticizing the starch, starch or modified starch containing equilibrium moisture within the above numerical range is preferred.

[0129] The starch used in this process may be plasticized. Plasticization of the starch can reduce the particle size of the starch granules to 2 μm or less. This makes it possible to make the surface of the molded article smooth and also improve the physical properties of the article (e.g., tensile elongation). Plasticization of starch can be achieved, for example, by heating the starch, or by contacting the starch with a polar organic compound that can gelatinize or plasticize the starch at a temperature higher than room temperature and then heating it.

[0130] Furthermore, by using the plasticized starch (hereinafter referred to as "plasticized starch"), it is possible to manufacture molded articles with good quality (for example, smooth surface, low discoloration, and low odor).

[0131] Furthermore, by using the plasticized starch, transparency can be imparted to the molded body. In addition, by using the plasticized starch, the surface of the molded body can be made smooth.

[0132] In this process, when mixing the starch and the first resin B1, the starch and the first resin B1 may be mixed directly. Alternatively, the first resin B1 may be mixed with a plasticized starch material that includes starch and a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature.

[0133] The plasticized starch materials used in this process will be described below.

[0134] <Plasticized starch material>

[0135] The plasticized starch material may be a material mainly composed of starch. The starch content in the plasticized starch material may be, for example, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, relative to the mass of the plasticized starch material. The starch content in the plasticized starch material may be, for example, preferably 99.5% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less, relative to the mass of the plasticized starch material. The starch content may be measured by TG measurement (thermogravimetric analysis) at 150°C. Specifically, the content may be determined based on the amount of mass change measured using a TG measuring device (STA7200, Hitachi High-Tech Science Corporation). The amount of mass change corresponds to the amount of decrease in volatile components, and the amount of decrease corresponds to the amount of polar organic compounds that can gelatinize or plasticize the starch. Therefore, the starch content in the plasticized starch material can be calculated using the following formula: (Starch content in the plasticized starch material (unit: mass%)) = (Mass after the start of measurement of the mass change) / (Mass before the start of measurement of the mass change) × 100. The measurement conditions for the mass change are as follows: Temperature range 25°C to 150°C, heating rate 20°C / min, under nitrogen.

[0136] In this specification, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature means a polar organic compound that can gelatinize or plasticize starch by contacting it at a temperature higher than room temperature. Organic compounds known in the art may be used as the polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature.

[0137] A polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature refers to a polar organic compound that is not capable of gelatinizing or plasticizing starch at room temperature but is capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. In this specification, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature is also referred to as a "polar organic compound capable of gelatinizing or plasticizing starch at high temperature." For example, if starch does not gelatinize or plasticize when a polar organic compound is brought into contact with starch at room temperature for one hour, but the starch does gelatinize or plasticize when the polar organic compound is brought into contact with starch at a high temperature for one hour, then the polar organic compound is "capable of gelatinizing or plasticizing starch at high temperature." The polar organic compound capable of gelatinizing or plasticizing starch may be any of the following: a polar organic compound capable of gelatinizing starch, a polar organic compound capable of plasticizing starch, or a polar organic compound capable of both gelatinizing and plasticizing starch.

[0138] In this specification, a temperature higher than room temperature (also referred to as "high temperature") refers to a temperature achieved by heat treatment. High temperature may be, for example, 50°C or higher, preferably 60°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher.

[0139] In this specification, room temperature refers to the temperature when no heat treatment is performed. Room temperature may be, for example, less than 50°C, preferably 10 to 40°C, more preferably 15 to 35°C, and even more preferably 20 to 30°C.

[0140] Preferably, the total content of polar organic compounds in the plasticized starch material that can gelatinize or plasticize the starch at temperatures higher than room temperature is, for example, preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less, relative to the mass of the plasticized starch material. The total content of polar organic compounds in the plasticized starch material that can gelatinize or plasticize the starch at temperatures higher than room temperature is, for example, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, relative to the mass of the plasticized starch material. The total content of polar organic compounds that can gelatinize or plasticize the starch at temperatures higher than room temperature is calculated by subtracting the content of gelatinized starch measured by the TG measurement described above from 100% by mass.

[0141] In this process, the polar organic compound capable of gelatinizing or plasticizing starch at temperatures higher than room temperature is preferably a liquid at room temperature. This facilitates mixing with starch.

[0142] The polar organic compound constituting the plasticized starch material, which can gelatinize or plasticize starch at temperatures higher than room temperature (high temperature), may contain at least one polyhydric alcohol.

[0143] A polyhydric alcohol is an alcohol having two or more hydroxyl groups in its molecule. Such a polyhydric alcohol is preferably a polyhydric alcohol having 2 to 5 carbon atoms, and more preferably a polyhydric alcohol having 2 to 4 carbon atoms. The said polyhydric alcohol preferably has 2 to 5 hydroxyl groups (OH groups), and more preferably has 2 to 4 hydroxyl groups (OH groups).

[0144] The aforementioned polyhydric alcohol may include, for example, glycerin and glycol. Examples of such glycols include ethylene glycol and propylene glycol.

[0145] The polyhydric alcohol may preferably comprise one or more combinations selected from glycerin, ethylene glycol, and propylene glycol. The plasticized starch material may contain, for example, preferably 10 to 40 parts by mass, and more preferably 20 to 35 parts by mass, of the polyhydric alcohol per 100 parts by mass of starch. Furthermore, the polyhydric alcohol content in the molded article may preferably be 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more.

[0146] From the viewpoint of suppressing bleeding under high temperature and high humidity conditions, the glycerin content in the molded article is preferably 0% to 10% by mass, more preferably 0% to 9% by mass, and even more preferably 0% to 7% by mass. The lower the amount of glycerin, the more effectively bleeding can be suppressed. Therefore, it is preferable to use other polyhydric alcohols instead of glycerin, for example, ethylene glycol or propylene glycol are preferred as substitutes for glycerin. In other words, from the viewpoint of suppressing bleeding, it is also possible to omit glycerin altogether and, for example, contain only ethylene glycol or only propylene glycol.

[0147] However, the starch granules may become larger as the glycerin content decreases. To reduce the size of the starch granules even when the glycerin content is reduced, the plasticized starch material may further contain organic acids. An organic acid is an organic compound that exhibits acidity, and an organic compound is a compound having at least one carbon atom. Examples of organic acids include carboxylic acids, sulfonic acids, sulfinic acids, organic phosphinic acids, and organic phosphonic acids.

[0148] Examples of the carboxylic acids mentioned above include monocarboxylic acids such as lactic acid, gluconic acid, acetic acid, and acetic anhydride; dicarboxylic acids such as tartaric acid, maleic acid, maleic anhydride, adipic acid, succinic acid, succinic anhydride, and malic acid; and carboxylic acids having three or more carboxyl groups, such as citric acid. Examples of the sulfonic acids mentioned above include benzenesulfonic acid and methanesulfonic acid. Examples of the sulfinic acids mentioned above include benzenesulfinic acid and cysteine ​​sulfonic acid. Examples of the organic phosphinic acids mentioned above include diethylphosphinic acid. Examples of the organic phosphonic acids mentioned above include methylphosphonic acid.

[0149] The aforementioned plasticized starch material may contain a polyhydric alcohol. This polyhydric alcohol may be, for example, a combination of glycerin and ethylene glycol, or ethylene glycol alone. In the case of ethylene glycol alone, it may also contain an organic acid.

[0150] In this process, the plasticized starch material can be gelatinized or plasticized by heating it at a temperature higher than room temperature in the presence of a polar organic compound capable of gelatinizing or plasticizing the starch. This gelatinization or plasticization may be brought about, for example, by the cleavage of intermolecular bonds (mainly hydrogen bonds) by heating in the presence of a polar organic compound capable of gelatinizing or plasticizing at high temperatures. The gelatinized or plasticized starch may be, for example, pregelatinized starch. This plasticization is thought to contribute to imparting transparency and / or smoothness to the molded article.

[0151] This plasticization is also thought to contribute to reducing the size of the starch particles contained in the molded article. For example, in a molded article formed from a starch-containing resin composition containing unplasticized starch, the starch particles tend to appear on the surface of the molded article. These starch particles have a particle size of, for example, about 20 μm. Therefore, for example, when forming a film using a starch-containing resin composition containing unplasticized starch, the content of the starch in the resin composition is limited to, for example, a maximum of about 30% by mass relative to the mass of the resin composition, in order to prevent the shape of the starch particles from appearing on the surface of the film. Furthermore, when the thickness of the film is about 20 μm or less, the starch particles become noticeably visible on the surface of the film. Furthermore, when attempting to manufacture a nonwoven fabric from a starch-containing resin composition containing unplasticized starch, the fiber thickness of the nonwoven fabric is approximately 20-30 μm, while the starch particle diameter is 20 μm. As a result, the size of the starch particles becomes almost the same as the fiber thickness, causing the starch particles to protrude outside the fibers and resulting in thread breakage. On the other hand, since the starch contained in the plasticized starch material is plasticized, the starch particle diameter becomes 2 μm or less, preventing the starch particles from protruding outside the fibers and thus preventing thread breakage. In addition, because the starch particle diameter is small, it is possible to provide fine threads and highly transparent nonwoven fabrics. Moreover, because the starch particle diameter is small, the shape of the starch is less likely to appear on the surface of the resin composition. For this reason, the starch content in the molded article can be more than 30% by mass relative to the mass of the molded article, for example, it may be 50% or more, particularly 60% or more, and even more particularly 70% or more. Even with a high starch content, the surface of the molded product remains smooth.

[0152] The first resin used in this process will be described below.

[0153] <First resin>

[0154] The first resin B1 may preferably be a thermoplastic resin. The thermoplastic resin may preferably be a polyolefin resin, a polyester resin, or a mixture thereof. The thermoplastic resin may also be a polystyrene resin.

[0155] Polyolefin resins are polymers obtained by polymerization using olefins (e.g., α-olefins) as the main monomers. These polyolefin resins may be, for example, polyethylene (PE) resin, polypropylene (PP) resin, or a combination of these resins.

[0156] The polyethylene resin may be, for example, low-density polyethylene (LDPE), high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA resin), or ultra-high molecular weight polyethylene (UHMW-PE), or a combination of these resins.

[0157] The polypropylene resin may be, for example, a homopolymer polypropylene resin, or a random copolymer or block copolymer polypropylene resin (e.g., an ethylene-propylene copolymer), or a combination of these resins.

[0158] The polyolefin resin may preferably be a biomass-derived polyolefin resin (for example, a biomass-derived polyethylene resin), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. This can reduce CO2 emissions.

[0159] The polyolefin resin may be a polyolefin resin produced using a metallocene catalyst. That is, the thermoplastic resin may be, for example, a metallocene catalyst-based polyethylene resin or polypropylene resin, or a combination of these resins.

[0160] The aforementioned polystyrene resin may also be a metallocene catalyst-based polystyrene resin.

[0161] Polyester resins are polymers formed by the polymerization of monomers via ester bonds. These polyester resins may include, for example, polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polylactic acid resin (PLA), or polycarbonate resin (PC), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), or a combination of two or more resins selected from these.

[0162] Polystyrene resins are polymers formed by the polymerization of styrene monomers. These polystyrene resins may include, for example, polystyrene resin, rubber-reinforced polystyrene resin (high-impact polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylic acid ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, and acrylonitrile-ethylene propylene-styrene copolymer, or any combination of two or more resins selected from these.

[0163] In this process, the type of first resin B1 may be appropriately selected by those skilled in the art, for example, depending on the type of molded article to be formed, but a thermoplastic resin with a low processing temperature is preferred. For example, when forming a film as the molded article, the thermoplastic resin is preferably a polyolefin resin. Such a polyolefin resin may be polyethylene resin or polypropylene resin.

[0164] In this process, the first resin B1 may be a biodegradable resin. Examples of biodegradable resins include biodegradable polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and polylactic acid (PLA), polybutylene succinate (PBS), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), as well as a mixture of two or more selected from the above biodegradable resins. In this embodiment, since both the first resin and the starch are biodegradable, the molded article according to this embodiment can be more environmentally friendly.

[0165] Furthermore, in order to suppress the elution of starch into water, the SP value of the first resin B1 is 7.8 (cal / cm). 1 / 2 More than 11.0 (cal / cm) 1 / 2 The following may apply. The SP value can be calculated by the method described above. From the viewpoint of suppressing the elution of starch into water, the resin B1 may preferably include at least one selected from ethylene-vinyl acetate copolymer (EVA resin) and polyethylene resin.

[0166] The first resin B1 is preferably a thermoplastic resin having a melting point of 90°C to 180°C, and more preferably a thermoplastic resin having a melting point of 95°C to 170°C. By using a thermoplastic resin with a lower melting point, the temperature during molding of the molded article can be lowered, and odor or discoloration caused by heating the starch can be further suppressed.

[0167] The first resin B1 may be in pellet or powder form, and is mixed and kneaded during molding using a single-screw extruder, twin-screw extruder, injection molding machine, etc., and uniformly dispersed.

[0168] In this process, preferably 30 parts by mass or more of the first resin B1 is added to 100 parts by mass of the starch, more preferably 40 parts by mass or more of the first resin B1 is added, even more preferably 50 parts by mass or more of the first resin B1 is added, and even more preferably 60 parts by mass or more of the first resin B1 is added.

[0169] In this process, the first resin B1 may be blended with 100 parts by mass of starch, preferably 95 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less. By mixing at this blending ratio, the size of the starch particles contained in the molded article can be reduced.

[0170] [Other ingredients]

[0171] In this process, other components may be added in addition to the starch and the first resin B1. Examples of such other components include compatibilizers, oxidative decomposition accelerators, colorants, and antioxidants.

[0172] The compatibilizer may be used to further improve the compatibility between the plasticized starch and the first resin B1, if the starch is a plasticized starch.

[0173] Examples of the compatibilizers include carboxylic acid anhydride-modified polyolefins, olefin-based graft-modified products, and olefin-based comonomers.

[0174] The carboxylic acid anhydride constituting the carboxylic acid anhydride-modified polyolefin is preferably maleic anhydride. The compatibilizer may be one or more selected from the group consisting of maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer.

[0175] The olefin-based graft-modified product may be an acid-modified polyolefin, and more specifically, a polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. The (unmodified) polyolefin used for graft modification may be, for example, polyethylene, polypropylene, or ethylene-α-olefin copolymer (ethylene-propylene copolymer), and may be particularly polypropylene. For example, the acid-modified polyolefin described in Japanese Patent Application Publication No. 2010-095671 may be used.

[0176] The aforementioned oxidative decomposition accelerator may be a combination of a carboxylate metal salt and a rare earth compound. An example of an oxidative decomposition accelerator containing such a combination is P-Life (manufactured by P-Life Japan Inc.).

[0177] The carboxylate metal salt contained in the oxidative decomposition accelerator may be, for example, a metal salt of an aliphatic carboxylic acid having 10 to 20 carbon atoms, and more preferably a metal stearate salt. The metal atom that forms the metal salt with the aliphatic carboxylic acid may be one or more combinations selected from, for example, cobalt, cerium, iron, aluminum, antimony, barium, bismuth, chromium, copper, gallium, lanthanum, lithium, magnesium, molybdenum, nickel, calcium, silver, sodium, tin, tungsten, vanadium, yttrium, zinc, and zirconium, and more preferably one or more combinations selected from calcium, magnesium, zinc, cobalt, cerium, iron, and copper. For example, the metal salt may be iron stearate. As the carboxylate salt, one type of carboxylate salt may be used alone, or a combination of two or more types of carboxylate salts may be used.

[0178] The rare earth compound contained in the oxidative decomposition accelerator may be, for example, a rare earth oxide, a rare earth hydroxide, a rare earth sulfate, a rare earth nitrate, a rare earth acetate, a rare earth chloride, or a rare earth carboxylate. More specifically, the rare earth compound may be one or more selected from cerium oxide, ceric sulfate, ceric ammonium sulfate, ceric ammonium nitrate, cerium acetate, lanthanum nitrate, cerium chloride, cerium nitrate, cerium hydroxide, cerium octolate, lanthanum oxide, yttrium oxide, and scandium oxide. The rare earth compound may be used alone or in combination of two or more rare earth compounds.

[0179] Examples of the coloring agent include titanium dioxide and / or carbon black. Examples of the antioxidant include, but are not limited to, phenolic antioxidants.

[0180] In this process, the following may preferably be included: starch, the first resin B1, the compatibilizer, and the oxidative decomposition accelerator. The composition ratio of the starch and the first resin B1 may, for example, preferably be 20 parts by mass:80 parts by mass to 80 parts by mass:20 parts by mass, more preferably 30 parts by mass:70 parts by mass to 80 parts by mass:20 parts by mass, and even more preferably 50 parts by mass:50 parts by mass to 80 parts by mass:20 parts by mass. The content of the compatibilizer may, for example, preferably be 1 to 10 parts by mass, and more preferably 2 to 9 parts by mass, based on 100 parts by mass of the total amount of the starch and the first resin B1. The content of the oxidative decomposition accelerator may, for example, preferably be 0.01 to 7 parts by mass, and more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the total amount of the starch and the first resin B1.

[0181] This process may include a first mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water, and a plasticized starch preparation step of preparing plasticized starch by heating the mixture obtained in the first mixing step to plasticize the starch.

[0182] Furthermore, in this process, starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, water, and raw materials such as the first resin B1 may be mixed first. The first resin B1 may be supplied in pellet form or in powder form. The mixing of the raw materials such as starch and the first resin B1 may be carried out, for example, by a commercially available stirrer or a mixer such as a Henschel mixer, tumbler mixer, Barber mixer, or kneader mixer. The mixing of the raw materials may be carried out at room temperature. Alternatively, after mixing the raw materials at room temperature, the mixed raw materials may naturally heat up to about 40°C. The kneading of the mixed raw materials may be carried out, for example, by a single-screw kneading extruder or a twin-screw kneading extruder. As these kneading extruders, devices known in the art may be used. Preferably, the starch-containing first resin preparation step includes at least a kneading process using a twin-screw kneading extruder. As the twin-screw compounding extruder, a twin-screw compounding extruder with co-rotation in both directions may be used, or a twin-screw compounding extruder with opposite rotation in both directions may be used. By performing the compounding process with a twin-screw compounding extruder, a starch-containing primary resin in which the starch is more uniformly dispersed can be obtained.

[0183] The starch-containing first resin preparation step may involve heating the first resin B1 to a temperature at which it can melt. This temperature may be appropriately selected by those skilled in the art depending on the melting point of the first resin B1 used. The kneading in this step may be carried out preferably at 80 to 200°C, more preferably at 90 to 170°C, and even more preferably at 95 to 180°C. The kneading time may be appropriately set.

[0184] In the starch-containing first resin preparation step, the starch-containing first resin may be subjected to the molding step as is, without being pelletized. This eliminates the need for the pelletizing step.

[0185] In addition, in the starch-containing first resin preparation step, the starch-containing first resin may be prepared by mixing starch and first resin B1 in a mixer, then extruding the strand using a single-screw or twin-screw extruder, cutting it to produce pellets, and using these pellets as a masterbatch in the molding step.

[0186] In the starch-containing first resin preparation step, preferably 30 parts by mass or more of the first resin B1 is blended with 100 parts by mass of the starch, more preferably 40 parts by mass or more of the first resin B1 is blended, even more preferably 50 parts by mass or more of the first resin B1 is blended, and even more preferably 60 parts by mass or more of the first resin B1 is blended.

[0187] In the starch-containing first resin preparation step, the first resin B1 may be blended in a quantity of 95 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less, of 100 parts by mass of starch.

[0188] [Starch-containing resin composition preparation process]

[0189] In the starch-containing resin composition preparation step, the starch-containing first resin and the second resin B2 are mixed to obtain the starch-containing resin composition.

[0190] The second resin B2 used in this process will be described below.

[0191] <Second resin>

[0192] The second resin B2 used in this process may be a different type of resin from the first resin B1 used in the starch-containing first resin preparation process, or it may be the same type of resin. The second resin B2 used in this process may preferably be a thermoplastic resin.

[0193] In the starch-containing resin composition preparation step, the thermoplastic resin used as the second resin B2 is preferably a polyolefin resin, a polyester resin, or a mixture thereof. Alternatively, the second resin B2 may be a polystyrene resin.

[0194] As the polyolefin resin, for example, polyethylene (PE) resin or polypropylene (PP) resin, or a combination of these resins may be used.

[0195] The polyethylene resin may be, for example, low-density polyethylene (LDPE), high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), or ultra-high molecular weight polyethylene (UHMW-PE), or a combination of these resins.

[0196] Such polyethylene resins may preferably be low-density polyethylene (LDPE), high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), or combinations thereof.

[0197] The polypropylene resin may be, for example, a homopolymer polypropylene resin, or a random copolymer or block copolymer polypropylene resin (e.g., an ethylene-propylene copolymer), or a combination of these resins.

[0198] The polyolefin resin may preferably be a biomass-derived polyolefin resin (e.g., biomass-derived polyethylene resin), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. This can reduce CO2 emissions.

[0199] The polyolefin resin may be a polyolefin resin produced using a metallocene catalyst. That is, the thermoplastic resin may be, for example, a metallocene catalyst-based polyethylene resin or polypropylene resin, or a combination of these resins.

[0200] In this process, the second resin B2 may be a biodegradable resin. Examples of biodegradable resins include biodegradable polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and polylactic acid (PLA), polybutylene succinate (PBS), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), as well as a mixture of two or more selected from the above biodegradable resins. In this embodiment, since both the starch-containing first resin and the starch are biodegradable, the molded article according to this embodiment can be more environmentally friendly.

[0201] Furthermore, in order to suppress the leaching of starch from the molded body into water, the SP value of the second resin B2 is set to 7.7 (cal / cm). 1 / 2 More than 8.4 (cal / cm) 1 / 2 The following is also acceptable.

[0202] Furthermore, preferably, the SP value of the first resin B1 and the SP value of the second resin B2 can satisfy the following relational expression. ΔSP B2W =|SP value of the second resin B2 -23.4 (cal / cm) 1 / 2 |>ΔSPB1W =|SP value of First Resin B1 - 23.4 (cal / cm) 1 / 2 |

[0203] As shown in the above relationship, the SP value of the second resin B2 and the SP value of water are 23.4 (cal / cm). 1 / 2 The absolute value of the difference between the two is 23.4 (cal / cm²), which is the SP value of the first resin B1 and the SP value of water. 1 / 2 It is preferable that the second resin B2 is greater than the absolute value of the difference between the two. In other words, it is preferable that the second resin B2 has less hydrophilicity than the first resin B1. Because the second resin B2 used in this process has less hydrophilicity than the first resin B1, in the starch-containing first resin preparation process, the starch is coated with the first resin B1, and then in this process, the starch is coated with the second resin B2, which has less hydrophilicity than the first resin B1, thereby suppressing the dissolution of starch contained in the starch-containing first resin into water.

[0204] The second resin B2 may be in pellet or powder form, and is mixed and kneaded during molding using a single-screw extruder, twin-screw extruder, injection molding machine, etc., and uniformly dispersed.

[0205] In this process, from the viewpoint of diluting the starch concentration in the starch-containing first resin, the second resin B2 may be mixed with the starch-containing first resin in an amount of preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more, per 100 parts by mass of the starch-containing first resin.

[0206] The second resin B2 may be mixed with the starch-containing first resin in an amount of preferably 170 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less, per 100 parts by mass of the starch-containing first resin.

[0207] <Other ingredients>

[0208] In this process, other components may be added in addition to the starch-containing first resin and the second resin B2. Examples of such other components include compatibilizers, oxidative decomposition accelerators, colorants, and antioxidants.

[0209] The compatibilizer may be used to further improve the compatibility between the starch-containing first resin and the second resin B2.

[0210] The compatibilizers used in this process are described below.

[0211] <Compatibilizer>

[0212] Examples of the compatibilizers include carboxylic acid anhydride-modified polyolefins, olefin-based graft-modified products, and olefin-based comonomers.

[0213] The carboxylic acid anhydride constituting the carboxylic acid anhydride-modified polyolefin is preferably maleic anhydride. The compatibilizer may be one or more combinations selected from the group consisting of, for example, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer.

[0214] The olefin-based graft-modified product may be an acid-modified polyolefin, and more specifically, a polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. The (unmodified) polyolefin used for graft modification may be, for example, polyethylene, polypropylene, or ethylene-α-olefin copolymer (ethylene-propylene copolymer), and may be particularly polypropylene. For example, the acid-modified polyolefin described in Japanese Patent Application Publication No. 2010-095671 may be used.

[0215] In this process, the compatibilizer may be mixed with the starch-containing first resin in an amount of preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the starch-containing first resin.

[0216] In this process, the mixing of the starch-containing first resin and the second resin B2 may be carried out using a single-screw extruder or a twin-screw extruder. The mixing temperature in this process is preferably 80 to 200°C, more preferably 90 to 170°C, and even more preferably 95 to 180°C. The mixing time can be set as appropriate.

[0217] [Molded object forming process]

[0218] In the molded body formation process, the starch-containing resin composition is molded to obtain a molded body that does not release starch.

[0219] In the molded article formation process, the starch-containing resin composition may be molded into a molded article by a molding method such as inflation molding using an inflation molding machine, T-die molding using a T-die extruder, calendering using a calendering machine, or injection molding using an injection molding machine.

[0220] In the above-mentioned various molding machines, the starch-containing resin composition is heated and melted to the molding temperature, extruded from the die and nozzle of the molding machine, and cooled to produce a molded body. The molding temperature range used is above the melting points of the first resin B1 and the second resin B2. When the raw materials are directly kneaded and mixed for molding, the range is preferably 95 to 200°C from the viewpoint of suppressing burning and decomposition of the raw materials, seizing inside the cylinder of the molding machine, and preventing starch from being discharged in an unmelted state, which can cause problems as the pressure rises. Furthermore, from the viewpoint of preventing burning and decomposition of the raw materials, the residence time of the starch-containing resin composition inside the cylinder of the molding machine is preferably no more than 10 minutes.

[0221] In this embodiment, the starch-containing resin composition may be molded into a film using an inflation molding machine, with the temperature set to 95-200°C. The film molded by the inflation molding machine may be cooled by setting the temperature of the take-up roll to 90°C or lower, and then taken up and wound up after being molded to a predetermined thickness.

[0222] The starch-containing resin composition may be molded into a sheet using a T-die extruder, with the temperature set to 150-200°C. The sheet extruded by the T-die extruder may be cooled by setting the temperature of the take-up roll to 60°C or lower, and then taken up and wound up after being molded to a predetermined thickness.

[0223] A film is a thin, membrane-like material, and its thickness is, for example, less than 200 μm, and more specifically, it can be between 10 μm and 200 μm. A sheet, on the other hand, is a thin, plate-like material, and its thickness is, for example, less than 200 μm, and more specifically, it can be between 10 μm and 200 μm.

[0224] Furthermore, in the molded product formation process, the starch-containing resin composition may be molded into food packaging bags, shopping bags, garbage collection bags, agricultural bags, containers (e.g., bottle containers), bottle caps, and corrugated plastic boxes by molding methods such as blow molding, injection molding, or shape extrusion molding. 3. Examples

[0225] The present invention will be described in more detail below based on the examples. The examples described below are representative examples of the present invention, and the scope of the present invention is not limited to these examples. The evaluation methods and evaluation criteria used in the examples are as follows.

[0226] (1) Potassium permanganate consumption test The consumption of potassium permanganate was measured using the following procedure. (i) The film was cut into 5cm squares and both sides were thoroughly washed with pure water. (ii) 100 mL of distilled water was placed in a beaker, and this beaker was heated in a water bath at 60°C. (iii) The washed film was immersed in distilled water in a beaker heated in a 60°C water bath and left for 30 minutes. The liquid in the beaker was used as the eluent. (iv) After 30 minutes, the film was removed and the eluate was filtered through filter paper. The mesh size of the filter paper was arbitrary. The filtered liquid was used as the filtrate. (v) To the filtrate, 5 mL of commercially available sulfuric acid diluted 3 times and 10 mL of 0.002 mol / L potassium permanganate solution were added and boiled for 5 minutes. (vi) After stopping the heating, the film was visually compared with the blank that had gone through steps (i) to (v) above, except that it was not immersed in the pure water in the beaker in step (ii) above. Non-elution properties were evaluated according to the following criteria. A: There is no color difference from the blank. B: Some color remains, but it is lighter than the blank. C: Becomes colorless.

[0227] Test Example 1: Film Manufacturing

[0228] (Example 1)

[0229] As shown in Table 1 below, 100 parts by mass of corn starch (product name: Showa Corn Starch, Showa Sangyo Co., Ltd.), 34 parts by mass of glycerin, and 27 parts by mass of water were prepared as plasticizing starch materials. These three components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin and water were pre-mixed before being added to the mixer.

[0230] The mixture obtained by this mixing was a powdery mixture.

[0231] The mixture obtained by the above mixing process was supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and the mixture was then subjected to a kneading process.

[0232] The cylinder temperature during the kneading process was 110°C. Suction was performed from the vent during the kneading process. After the kneading process, the mixture was extruded from the die of the extruder, and an elongated, roughly cylindrical plasticized starch (hereinafter also referred to as "plasticized starch of Example 1 (masterbatch)") was obtained.

[0233] 50 parts by mass of plasticized starch from Example 1, and ethylene-vinyl acetate copolymer (750, manufactured by Tosoh Corporation, SP value: 9.1 (cal / cm)) as the first resin B1. 1 / 2 50 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin (hereinafter also referred to as "Starch-containing resin of Example 1") was obtained by this kneading process.

[0234] Example 1 consists of 60 parts by mass of the starch-containing first resin and, as the second resin B2, linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)). 1 / 2 40 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 1") was obtained by this kneading process. The starch-containing resin composition of Example 1 contains 30 parts by mass of plasticized starch.

[0235] The starch-containing resin composition of Example 1 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150°C), and inflation molding was performed. The inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0236] A potassium permanganate consumption test was conducted on the film, and the non-elution and elution properties of starch were evaluated according to the above method and criteria. The evaluation results are shown in Table 1 below. The film contained an extremely small amount of starch that dissolved in water. The ΔSP of the obtained film B2W =|SP value of the second resin B2 -23.4 (cal / cm) 1 / 2 |=|7.9-23.4(cal / cm) 1 / 2 |=15.5 (cal / cm) 1 / 2 It was. Also, ΔSP B1W =|SP value of First Resin B1 - 23.4 (cal / cm) 1 / 2 |=|9.1-23.4(cal / cm) 1 / 2 |=14.3 (cal / cm) 1 / 2 That was the case.

[0237] [Table 1]

[0238] (Example 2)

[0239] Using the same method as in Example 1, an elongated, nearly cylindrical plasticized starch (hereinafter also referred to as "plasticized starch of Example 2 (masterbatch)") was obtained.

[0240] As shown in Table 1 above, in the twin-screw extruder, instead of ethylene-vinyl acetate copolymer (750, Tosoh Corporation), linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)) is used as the primary resin. 1 / 2A starch-containing first resin (hereinafter also referred to as "the starch-containing first resin of Example 2") was obtained in the same manner as in Example 1, except that 50 parts by mass were mixed in.

[0241] Example 2 consists of 60 parts by mass of the starch-containing first resin and a second resin consisting of linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)). 1 / 2 40 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 2") was obtained by this kneading process. The starch-containing resin composition of Example 2 contains 30 parts by mass of plasticized starch.

[0242] Using the starch-containing resin composition of Example 2, inflation molding was performed in the same manner as in Example 1. This inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0243] The same evaluation was performed in Example 2 as in Example 1. The evaluation results are shown in Table 1 above. The film contained a small amount of starch that dissolved in water.

[0244] (Example 3)

[0245] As shown in Table 1 above, 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, manufactured by Matsutani Chemical Industry Co., Ltd.), 15 parts by mass of glycerin, 19 parts by mass of ethylene glycol, and 27 parts by mass of water were prepared as the plasticizing starch material. These four components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and water were pre-mixed before being added to the mixer.

[0246] The mixture obtained by the mixing was a powdery mixture.

[0247] The mixture obtained by the mixing was supplied into a twin-screw extruder (PCM30, Ikegai Corporation), and the mixture was subjected to kneading treatment.

[0248] The cylinder temperature in the kneading treatment was 110°C. In the kneading treatment, suction from the vent was performed. After the kneading treatment, the mixture was extruded from the die of the extruder, and an elongated substantially cylindrical plasticized starch (hereinafter, also referred to as "the plasticized starch (masterbatch) of Example 3") was obtained.

[0249] 50 parts by mass of the plasticized starch of Example 3, 50 parts by mass of an ethylene-vinyl acetate copolymer (750, manufactured by Tosoh Corporation, SP value: 9.1 (cal / cm) 1 / 2 ) as the first resin, and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Corporation), and these components were subjected to kneading treatment. The screw temperature in the kneading treatment was 170°C, and the resin pressure was 4.2 MPa. In the kneading treatment, suction from the vent was performed. By the kneading treatment, a starch-containing first resin (hereinafter, also referred to as "the starch-containing first resin of Example 3") was obtained.

[0250] 60 parts by mass of the starch-containing first resin of Example 3, and a linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Japan Polyethylene Corporation, SP value: 7.9 (cal / cm) 1 / 240 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 3") was obtained by this kneading process. The starch-containing resin composition of Example 3 contains 30 parts by mass of plasticized starch.

[0251] The starch-containing resin composition of Example 3 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150°C), and inflation molding was performed. The inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0252] In Example 3, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. The film had a low amount of starch that dissolved in water. The ΔSP of the obtained film B2W =|SP value of the second resin B2 -23.4 (cal / cm) 1 / 2 |=|7.9-23.4(cal / cm) 1 / 2 |=15.5 (cal / cm) 1 / 2 It was. Also, ΔSP B1W =|SP value of First Resin B1 - 23.4 (cal / cm) 1 / 2 |=|9.1-23.4(cal / cm) 1 / 2 |=14.3 (cal / cm) 1 / 2 That was the case.

[0253] (Example 4)

[0254] As shown in Table 1 above, 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, manufactured by Matsutani Chemical Industry Co., Ltd.), 15 parts by mass of glycerin, 19 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were prepared as the plasticizing starch material. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and water were pre-mixed before being added to the mixer.

[0255] The mixture obtained by this mixing was a powdery mixture.

[0256] The mixture obtained by the above mixing process was supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and the mixture was then subjected to a kneading process.

[0257] The cylinder temperature during the kneading process was 110°C. Suction was performed from the vent during the kneading process. After the kneading process, the mixture was extruded from the die of the extruder, and an elongated, roughly cylindrical plasticized starch (hereinafter also referred to as "plasticized starch of Example 4 (masterbatch)") was obtained.

[0258] 50 parts by mass of plasticized starch from Example 4, and linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)) as the first resin. 1 / 2 50 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.2 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin (hereinafter also referred to as "Starch-containing resin of Example 4") was obtained by this kneading process. Note that 30 parts by mass of plasticized starch were added to the starch-containing resin composition of Example 4.

[0259] Example 4 consists of 60 parts by mass of the starch-containing first resin and a second resin consisting of linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)). 1 / 2 40 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 4") was obtained by this kneading process.

[0260] The starch-containing resin composition of Example 4 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150°C), and inflation molding was performed. The inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0261] The same evaluation was performed in Example 4 as in Example 1. The evaluation results are shown in Table 1 above. The film contained a small amount of starch that dissolved in water.

[0262] (Example 5)

[0263] As shown in Table 1 above, 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, manufactured by Matsutani Chemical Industry Co., Ltd.), 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were prepared as the plasticizing starch material. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and water were pre-mixed before being added to the mixer.

[0264] The mixture obtained by this mixing was a powdery mixture.

[0265] The mixture obtained by the above mixing process was supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and the mixture was then subjected to a kneading process.

[0266] The cylinder temperature during the kneading process was 110°C. Suction was performed from the vent during the kneading process. After the kneading process, the mixture was extruded from the die of the extruder, and an elongated, roughly cylindrical plasticized starch (hereinafter also referred to as "plasticized starch of Example 5 (masterbatch)") was obtained.

[0267] 70 parts by mass of plasticized starch from Example 5, and ethylene-vinyl acetate copolymer (750, manufactured by Tosoh Corporation, SP value: 9.1 (cal / cm)) as the first resin. 1 / 2 30 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.2 MPa. Suction was performed from the vent during the kneading process. A starch-containing first resin (hereinafter also referred to as "the starch-containing first resin of Example 5") was obtained by this kneading process.

[0268] Example 5 consists of 45 parts by mass of the starch-containing first resin and a second resin consisting of linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)). 1 / 2 50 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 5") was obtained by this kneading process. The starch-containing resin composition of Example 5 contains 30 parts by mass of plasticized starch.

[0269] The starch-containing resin composition of Example 5 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150 °C), and inflation molding was performed. The inflation molding was carried out at 150 °C to 160 °C. By this inflation molding, a film with a thickness of 40 μm was obtained.

[0270] Also in Example 5, the same evaluation as in Example 1 was carried out. The evaluation results are as shown in Table 1 above. It was a film with a small amount of starch dissolved in water. The ΔSP of the obtained film B2W = |SP value of the second resin B2 - 23.4 (cal / cm) 1 / 2 | = |7.9 - 23.4 (cal / cm) 1 / 2 | = 15.5 (cal / cm) 1 / 2 was. Also, ΔSP B1W = |SP value of the first resin B1 - 23.4 (cal / cm) 1 / 2 | = |9.1 - 23.4 (cal / cm) 1 / 2 | = 14.3 (cal / cm) 1 / 2 was.

[0271] (Comparative Example 1)

[0272] In Comparative Example 1, without preparing the starch-containing first resin, 30 parts by mass of the plasticized starch of Example 1 and a linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm) 1 / 270 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "comparative example 1 starch-containing resin composition") was obtained by this kneading process. Note that comparative example 1 starch-containing resin composition contains 30 parts by mass of plasticized starch.

[0273] The starch-containing resin composition of Comparative Example 1 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150°C), and inflation molding was performed. The inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0274] The same evaluation was performed in Comparative Example 1 as in Example 1. The evaluation results are shown in Table 1 above. The film had an extremely high amount of starch that dissolved in water.

[0275] (Comparative Example 2)

[0276] In Comparative Example 2, instead of preparing the first starch-containing resin, 30 parts by mass of the plasticized starch from Example 5 and a linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd., SP value: 7.9 (cal / cm)) were used as the second resin. 1 / 270 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "Comparative Example 2's starch-containing resin composition") was obtained by this kneading process. Note that 30 parts by mass of plasticized starch were added to the starch-containing resin composition of Comparative Example 2.

[0277] The starch-containing resin composition of Comparative Example 2 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150°C), and inflation molding was performed. The inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0278] The same evaluation was performed in Comparative Example 2 as in Example 1. The evaluation results are shown in Table 1 above. The film had an extremely high amount of starch that dissolved in water.

[0279] (Summary of evaluation results)

[0280] Examples 1-5 showed low starch leaching in water and were suitable films for primary food packaging. On the other hand, Comparative Examples 1 and 2 showed high starch leaching in water and were not suitable films for primary food packaging.

[0281] (Example 6)

[0282] As plasticizing starch materials, 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, manufactured by Matsutani Chemical Industry Co., Ltd.), 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were prepared. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and water were pre-mixed before being added to the mixer.

[0283] The mixture obtained by this mixing was a powdery mixture.

[0284] The mixture obtained by the above mixing process was supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and the mixture was then subjected to a kneading process.

[0285] The cylinder temperature during the kneading process was 110°C. Suction was performed from the vent during the kneading process. After the kneading process, the mixture was extruded from the die of the extruder, and an elongated, roughly cylindrical plasticized starch (hereinafter also referred to as "plasticized starch of Example 6 (masterbatch)") was obtained.

[0286] 50 parts by mass of plasticized starch from Example 6, and as the first resin, biodegradable resin PBAT (product name Ecoflex®, manufactured by BASF Japan Ltd., SP value: 10.7 (cal / cm)) 1 / 2 50 parts by mass of the components were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.2 MPa. Suction was performed from the vent during the kneading process. A starch-containing first resin (hereinafter also referred to as "the starch-containing first resin of Example 6") was obtained by this kneading process.

[0287] Example 6 consists of 60 parts by mass of the starch-containing first resin and a second resin made of biodegradable resin PBAT (product name Ecoflex®, manufactured by BASF Japan Ltd., SP value: 10.7 (cal / cm)). 1 / 2 40 parts by mass of ) and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature during the kneading process was 170°C, and the resin pressure was 4.4 MPa. Suction was performed from the vent during the kneading process. A starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 6") was obtained by this kneading process. The starch-containing resin composition of Example 6 contains 30 parts by mass of plasticized starch.

[0288] The starch-containing resin composition of Example 6 was supplied to an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 150°C), and inflation molding was performed. The inflation molding was carried out at 150°C to 160°C. A film with a thickness of 40 μm was obtained by this inflation molding.

[0289] In Example 6, the same evaluation was performed as in Example 1. The film had a low amount of starch that dissolved in water.

[0290] Although embodiments and examples of this technology have been described in detail above, this technology is not limited to the embodiments and examples described above, and various modifications based on the technical concept of this technology are possible.

[0291] For example, the configurations, methods, processes, shapes, materials, and numerical values ​​listed in the above embodiments and examples are merely examples, and different configurations, methods, processes, shapes, materials, and numerical values ​​may be used as needed. Furthermore, the chemical formulas of compounds are representative examples, and the general name of the same compound is not limited to those listed.

[0292] Furthermore, the configurations, methods, processes, shapes, materials, and numerical values ​​of the above-described embodiments and examples can be combined with each other, as long as they do not deviate from the spirit of this technology.

[0293] Furthermore, in this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described stepwise in this specification, the upper or lower limit of one step in the numerical range may be replaced with the upper or lower limit of another step in the numerical range. Unless otherwise specified, the materials exemplified in this specification may be used individually or in combination of two or more.

Claims

1. A starch-containing first resin preparation step involves mixing plasticized starch, which is made by plasticizing starch, ethylene-vinyl acetate copolymer (EVA), which is the first resin, and a carboxylic acid-modified polyolefin, which is the compatibilizer, to obtain a starch-containing first resin. A starch-containing resin composition preparation step involves mixing the starch-containing first resin, a second resin different from the first resin, and a carboxylic acid-modified polyolefin (excluding the carboxylic acid-modified polyolefin contained in the starch-containing first resin) to obtain a starch-containing resin composition, and A molded body forming step in which the starch-containing resin composition is molded to obtain a starch-non-leaching molded body, Includes, The aforementioned plasticized starch contains at least one of glycerin and ethylene glycol, and water. A method for producing a starch-non-leaching molded article, wherein the starch non-leaching property of the molded article is determined by a potassium permanganate consumption test that evaluates the leaching of starch contained in the molded article into water.

2. The method for producing a starch-non-leaching molded article according to claim 1, wherein the starch-non-leaching molded article is a film.

3. A method for producing a starch-non-eluting molded article according to claim 1 or 2, wherein in the starch-containing first resin preparation step, 30 parts by mass or more of the first resin are blended with 100 parts by mass of the starch.

4. A method for producing a starch-non-eluting molded article according to any one of claims 1 to 3, wherein in the starch-containing resin composition preparation step, 60 parts by mass or more of the second resin is blended with 100 parts by mass of the first starch-containing resin.

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