Starch non-eluting film, and molding manufacturing method

Abstract

To provide a film which has a small amount of starch eluted to water, and enables primary packaging of a food product, while containing starch as a biomass base material.SOLUTION: A starch non-eluting film is formed of a starch-containing resin composition which contains a starch-containing a first resin containing plasticized starch obtained by plasticizing starch, an ethylene-vinyl acetate copolymer (EVA) as a first resin and anhydrous carboxylic acid-modified polyolefin as a compatibilizing agent, a second resin different from the first resin, and anhydrous carboxylic acid-modified polyolefin (excluding anhydrous carboxylic acid-modified polyolefin contained in the starch-containing first resin), wherein the plasticized starch contains at least one of glycerol and ethylene glycol, and water, and starch non-eluting property of the starch non-eluting film is non-eluting property determined by a potassium permanganate consumption test for evaluating eluting property of water to starch contained in the film.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, various films have been developed as packaging materials for packaging various articles such as foods, pharmaceuticals, cosmetics, and sanitary products. Conventional films are formed from petroleum-based materials, so they are difficult to decompose in the natural environment after being discarded, which is one of the causes of polluting the natural environment. In recent years, materials that can be decomposed in the natural environment after being discarded have been studied, and films containing biomass materials have attracted attention as such materials. Since the film contains biomass materials as an alternative to petroleum-based materials, it is possible to reduce CO2 emissions during combustion. Examples of biomass materials include waste-based biomass (such as food waste, livestock excrement, construction waste, and waste paper), unused biomass (such as non-edible parts of crops and forest residues), and resource grains. More specific examples of biomass materials include, for example, wood powder, 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 the same amount as the 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 as it is, and has difficulties in molding processability. Therefore, starches with imparted plasticity are used by various methods. Regarding a plastic molded body containing starch, for example, in Patent Document 1 below, an article containing a polymer content including a starch-based polymer material containing a first starch and a second starch and a polyolefin-based polymer material, wherein the amount of the polymer content that biodegrades after 91 days is based on the result of a biomethane potential test conducted at a temperature of about 52°C using an inoculum material having about 55 wt% water and about 45 wt% organic solids, and is more than the amounts of the first starch and the second starch, is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Films used for primary packaging of food are 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, despite containing starch as a biomass material.

Means for Solving the Problems

[0006] The present technology provides a starch non-eluting film formed from a thermoplastic resin containing starch. The starch non-eluting property of the starch non-eluting film may be non-elution determined by a potassium permanganate consumption test for evaluating the elution of starch contained in the film into water. The starch may be plasticized starch. The starch may be corn starch and / or tapioca starch. The thermoplastic resin may contain a first resin B1 having an SP value of 7.8 (cal / cm) 1 / 2 or more and 11.0 (cal / cm) 1 / 2 or less. The first resin B1 may be an ethylene-vinyl acetate copolymer (EVA). The thermoplastic resin may contain a second resin B2 having an SP value of 7.7 (cal / cm) 1 / 2 or more and 8.4 (cal / cm) 1 / 2 or less. The second resin B2 may be a polyethylene resin. The SP value of the first resin B1 and the SP value of the second resin B2 may 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 | The thermoplastic resin may contain a compatibilizer. The compatibilizer may be a carboxylic anhydride-modified polyolefin. The use of the starch non-eluting film may be for food packaging. The thermoplastic resin may be a biodegradable resin. The present technology includes a step of preparing a starch-containing first resin by mixing starch and a first resin B1 to obtain a starch-containing first resin, a step of preparing a starch-containing resin composition by mixing the starch-containing first resin and a second resin B2 to obtain a starch-containing resin composition, and a step of forming a molded body by molding the starch-containing resin composition, wherein the molded body is starch non-eluting, and provides a method for manufacturing the molded body. The molded article 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 elution 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 only to these embodiments.

[0009] The present technology will be described in the following order. 1. First Embodiment (Example of Starch-Non-Eluting Film) (1) Film Configuration (2) Physical Properties (3) Film Manufacturing Method (4) Film Applications 2. Second Embodiment (Example of Method for Manufacturing a Molded Body) (1) Method for Manufacturing a Molded Body 3. Examples

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

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

[0012] Hereinafter, the thermoplastic resin forming the starch-non-eluting film according to the first embodiment will be described in more detail.

[0013] [Thermoplastic Resin]

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

[0015] The polyolefin-based resin is a polymer obtained by polymerization using olefins (for example, α-olefins) as main monomers. The polyolefin-based resin may be, for example, a polyethylene (PE) resin or a polypropylene (PP) resin, or a combination of these resins.

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

[0018] The polyolefin resin may preferably be a polyolefin resin derived from biomass (for example, a biomass-derived polyethylene resin, etc.), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. Thereby, the CO 2 emission can be reduced.

[0019] The polyolefin resin may also 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 polystyrene resin may also be a metallocene catalyst-based polystyrene resin.

[0021] The polyester resin is a polymer formed by the polymerization of monomers through ester bonds. The polyester resin may be, 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 of these resins selected therefrom.

[0022] The polystyrene resin is a polymer formed by the polymerization of styrene monomers. The polystyrene resin may be, for example, polystyrene resin, rubber-reinforced polystyrene resin (impact-resistant polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylic acid ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, and acrylonitrile-ethylene propylene-styrene copolymer, etc., or a combination of two or more of these resins selected therefrom.

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

[0024] Also, 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 or more and 11.0 (cal / cm) 1 / 2Preferably, it may contain a first resin B1 as follows. The SP value can be calculated by Fedors' estimation method or the like. Examples of such a first resin B1 include polyethylene resins. For example, preferably, ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA resin) and the like can be mentioned.

[0025] Further, the thermoplastic resin preferably may contain a second resin B2 having an SP value of 7.7 (cal / cm) 1 / 2 or more and 8.4 (cal / cm) 1 / 2 or less. Examples of such a second resin B2 include polyethylene resins. For example, low-density polyethylene resin (LDPE: Low Density Polyethylene), high-density polyethylene resin (HDPE: High Density Polyethylene), very-low-density polyethylene resin (VLDPE: Very Low Density Polyethylene), linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene), and the like can be mentioned.

[0026] The first resin B1 and the second resin B2 may be of the same type of resin or 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 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 |

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

[0029] The thermoplastic resin for forming the starch non-eluting film according to the first embodiment preferably has a melting point of 90°C to 180°C, and more preferably may have a melting point of 95°C to 170°C. By adopting a thermoplastic resin having a lower melting point, the temperature during film formation can be lowered, and odors or coloring caused by heating of the starch contained in the thermoplastic resin can be more suppressed.

[0030] The thermoplastic resin may be in the form of pellets or powder, and is mixed, kneaded, and uniformly dispersed during molding by an extruder, an injection molding machine, or the like.

[0031] In the starch non-eluting 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 mixtures of two or more selected from among polylactic acid (PLA), polybutylene succinate (PBS), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH). In this embodiment, since both the thermoplastic resin and the starch are biodegradable, the starch non-eluting film according to this embodiment can be more environmentally friendly.

[0032] Hereinafter, the starch contained in the thermoplastic resin for forming the starch non-eluting film according to the first embodiment will be described in more detail.

[0033] [Starch]

[0034] Examples of the starch contained in the thermoplastic resin include underground starch and aboveground starch.

[0035] Underground starch is starch accumulated underground, for example, starch accumulated in underground stems or roots. Examples of underground starch include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, kudzu starch, and bracken starch.

[0036] Above-ground starch is starch accumulated above ground, for example, starch accumulated in seeds. Examples of above-ground starch include, but are not limited to, corn starch, wheat starch, sago starch, acorn starch, and rice starch.

[0037] The thermoplastic resin for 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 product of starch (i.e., modified starch), particularly a modified product of underground starch. Such modified products include physically modified starch physically modified or chemically modified chemically modified starch. Examples of physically modified starch include, for example, alpha starch, wet heat starch, etc. Examples of chemically modified starch include, for example, acetatoacetic acid esterified starch, acetic acid esterified starch, hydroxymethyl etherified starch, hydroxypropyl etherified starch, carboxymethyl etherified starch, allyl etherified starch, methyl etherified starch, succinic acid esterified starch, xanthan acetic acid esterified starch, nitric acid esterified starch, urea phosphate esterified starch, phosphate esterified starch, phosphate crosslinked starch, formaldehyde crosslinked starch, acrolein crosslinked starch, epichlorohydrin crosslinked starch, etc. Modified products can be plasticized at a lower temperature compared to unmodified starch. Therefore, the odor and / or coloring associated with heating during the production of plasticized starch described below can be suppressed.

[0039] The starch contained in the thermoplastic resin may preferably contain equilibrium moisture. The amount of equilibrium moisture is, for example, preferably 10% by mass to 15% by mass, more preferably 10% by mass to 14% by mass, still more preferably 10% by mass to 13% by mass, and even more preferably 11% by mass to 13% by mass, based on the starch mass. 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 contains the starch and the thermoplastic resin, for example, preferably in a ratio of 5 parts by mass:95 parts by mass to 75 parts by mass:25 parts by mass, more preferably in a ratio of 10 parts by mass:90 parts by mass to 70 parts by mass:30 parts by mass, and still more preferably in a ratio of 15 parts by mass:75 parts by mass to 70 parts by mass:30 parts by mass. The thermoplastic resin having such a ratio can reduce the starch granules contained in the starch non-eluting film.

[0041] The starch contained in the thermoplastic resin may be plasticized. When the starch is plasticized, the particle diameter of the starch granules can be 2 μm or less. Thereby, the surface of the starch non-eluting film formed from the thermoplastic resin can be smoothed, and for example, the physical properties (such as tensile elongation) of the starch non-eluting film can also be improved. Plasticization of the starch can be achieved, for example, by a method of heating the starch, or a method of 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.

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

[0043] Further, by including the plasticized starch in the thermoplastic resin, transparency can be imparted to the thermoplastic resin and the starch non-eluting film formed from the thermoplastic resin. Further, by including the plasticized starch in the thermoplastic resin, the surface of the thermoplastic resin and the starch non-eluting film formed from the thermoplastic resin can be smoothed.

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

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

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

[0047] By containing the plasticized starch in the thermoplastic resin, excellent moldability can be achieved when producing a starch non-eluting film from the thermoplastic resin. Also, the physical properties of the starch non-eluting film can be improved. For example, when the content ratio of starch (for example, ungelatinized starch, etc.) known so far 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 formed starch non-eluting 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 in the thermoplastic resin. Furthermore, even if it expands, the starch non-eluting film obtained by the molding may have poor stretchability, so the film may be easily torn and may not have excellent strength.

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

[0049] Hereinafter, the plasticized starch material will be described.

[0050] <Plasticized Starch Material>

[0051] The plasticized starch material may be a material mainly composed of starch. The content ratio of starch in the plasticized starch material may be, for example, preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, based on the mass of the plasticized starch material. The content ratio of starch in the plasticized starch material may be, for example, preferably 99.5% by mass or less, more preferably 99% by mass or less, and still more preferably 98% by mass or less, based on the mass of the plasticized starch material. The content ratio of the starch may be measured by TG measurement (thermogravimetric analysis) at 150°C. Specifically, the content ratio may be determined based on the mass change amount measured using a TG measurement device (STA7200, Hitachi High-Tech Science Corporation). The mass change amount corresponds to the reduction amount of volatile components, and the reduction amount corresponds to the amount of the polar organic compound capable of gelatinizing or plasticizing the starch. Therefore, the content ratio of starch in the plasticized starch material is obtained by the following formula: (content ratio of starch in the plasticized starch material (unit: % by mass)) = (mass after the start of measurement of the mass change amount) / (mass before the start of measurement of the mass change amount) × 100. The measurement conditions of the mass change amount are as follows: temperature range 25°C to 150°C, heating rate 20°C / min, under nitrogen.

[0052] In this specification, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature refers to a polar organic compound capable of gelatinizing or plasticizing the starch by contacting the starch at a temperature higher than room temperature. As the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, an organic compound known in the art may be used.

[0053] The polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature refers to a polar organic compound that cannot gelatinize or plasticize the starch at room temperature but can gelatinize or plasticize the starch at a temperature higher than room temperature. In this specification, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is also referred to as "a polar organic compound capable of gelatinizing or plasticizing the starch at high temperature". For example, when the starch does not gelatinize or plasticize even if the polar organic compound and the starch are brought into contact at room temperature for 1 hour, but the starch gelatinizes or plasticizes by bringing the polar organic compound and the starch into contact at high temperature for 1 hour, the polar organic compound is "capable of gelatinizing or plasticizing the starch at high temperature". The polar organic compound capable of gelatinizing or plasticizing the starch may be any of a polar organic compound capable of gelatinizing the starch, a polar organic compound capable of plasticizing the starch, and a polar organic compound capable of both gelatinizing and plasticizing the starch.

[0054] In this specification, the temperature higher than room temperature (also referred to as "high temperature") refers to the temperature achieved by heat treatment. The high temperature can be, for example, a temperature of 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 can be, for example, less than 50 °C, preferably 10 to 40 °C, more preferably 15 °C to 35 °C, and even more preferably 20 to 30 °C.

[0056] Preferably, the total content ratio of the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature in the plasticized starch material 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, based on the mass of the plasticized starch material. The total content ratio of the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature in the plasticized starch material 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, based on the mass of the plasticized starch material. The total content ratio of the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is calculated by subtracting the content ratio of the gelatinized starch measured by the TG measurement described above from 100% by mass.

[0057] The polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is preferably liquid at room temperature. Thereby, mixing with starch can be easily performed.

[0058] The polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature (high temperature) that constitutes the plasticized starch material may contain at least one polyhydric alcohol.

[0059] The polyhydric alcohol refers to an alcohol having two or more hydroxyl groups in the 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 polyhydric alcohol preferably has 2 to 5 hydroxyl groups (OH groups), and more preferably 2 to 4 hydroxyl groups (OH groups).

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

[0061] The polyhydric alcohol may preferably contain one or a combination of two or more selected from glycerin, ethylene glycol, and propylene glycol. The plasticized starch material may contain the polyhydric alcohol in an amount of, for example, preferably 10 parts by mass to 40 parts by mass, more preferably 20 parts by mass to 35 parts by mass, based on 100 parts by mass of starch. Further, 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 still more preferably 10% by mass or more.

[0062] From the viewpoint of suppressing the occurrence of bleed under high-temperature and high-humidity conditions, the content of glycerin in the starch non-eluting film may preferably be 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more and 9% by mass or less, and still more preferably 0% by mass or more and 7% by mass or less. The less the amount of glycerin, the more the occurrence of bleed can be suppressed. Therefore, it is better to use other polyhydric alcohols or the like instead of glycerin without using glycerin. For example, it is preferable to use ethylene glycol or propylene glycol instead of glycerin. That is, from the viewpoint of suppressing the occurrence of bleed, it may contain only ethylene glycol or only propylene glycol, for example, without containing any glycerin.

[0063] However, the starch granules may become larger as the glycerin content decreases. Even if the glycerin content is decreased, the plasticized starch material may further contain an organic acid in order to make the starch granules smaller. The organic acid refers to an organic compound showing acidity, and the organic compound refers to a compound having at least one carbon atom. Examples of the organic acid include carboxylic acid, sulfonic acid, sulfinic acid, organic phosphinic acid, and organic phosphonic acid.

[0064] Examples of the carboxylic acid 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 acid include benzenesulfonic acid and methanesulfonic acid. Examples of the sulfinic acid include benzenesulfinic acid and cysteine sulfonic acid. Examples of the organic phosphinic acid include diethylphosphinic acid. Examples of the organic phosphonic acid include methylphosphonic acid.

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

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

[0067] [Other components]

[0068] The thermoplastic resin for 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 the other components include a compatibilizer, an oxidation decomposition accelerator, a colorant, an antioxidant, and cellulose nanofibers.

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

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

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

[0072] The olefin-based graft-modified product may be an acid-modified polyolefin, and more specifically, may be a polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. Examples of the (unmodified) polyolefin used for graft modification may include polyethylene, polypropylene, or an ethylene-α-olefin copolymer (ethylene-propylene copolymer), and particularly may be polypropylene. For example, the acid-modified polyolefin described in JP-A-2010-095671 may be used.

[0073] The oxidation decomposition accelerator may be a combination of a carboxylic acid metal salt and a rare earth compound. Examples of the oxidation decomposition accelerator containing such a combination include, for example, P-Life (manufactured by Pei Life Japan Ink Co., Ltd.).

[0074] The metal carboxylate 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 may be a metal stearate. The metal atom forming the metal salt with the aliphatic carboxylic acid may be, for example, one or a combination of two or more selected from 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 may be one or a combination of two or more selected from calcium, magnesium, zinc, cobalt, cerium, iron, and copper. For example, the metal salt may be iron stearate. As the carboxylate, one type of carboxylate may be used alone, or a combination of two or more types of carboxylates 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 a combination of two 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 octylate, lanthanum oxide, yttrium oxide, and scandium oxide. As the rare earth compound, one type of rare earth compound may be used alone, or a combination of two or more types of rare earth compounds may be used.

[0076] As an example of the colorant, titanium oxide and / or carbon black may be used. Further, as an example of the antioxidant, a phenolic antioxidant may be used, but is not limited thereto.

[0077] The above-mentioned cellulose nanofiber (hereinafter also referred to as CNF) may be a commercially available CNF. Different from molecular cellulose, CNF can mean fibrous cellulose with an average fiber diameter of 10 nm to 3000 nm that is hardly soluble in a solvent. The average fiber diameter is preferably 10 nm to 1000 nm, more preferably 10 nm to 500 nm, still more preferably 10 nm to 300 nm, and even more preferably 10 nm to 100 nm. The aspect ratio of CNF can be, for example, preferably 30 to 10000, more preferably 50 to 5000, and still 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 average values of any 10 cellulose fibers observed with an electron microscope.

[0078] CNF is hydrophilic. Since CNF is generally produced by nanosizing a cellulose material by disintegrating it with water, it is dispersed in water.

[0079] CNF is used, for example, to enhance the strength of a thermoplastic resin. However, since a thermoplastic resin is often hydrophobic, it may be difficult to mix hydrophilic CNF with a thermoplastic resin. Therefore, for example, modified and hydrophobized CNF (especially powdered CNF) is mixed with a thermoplastic resin. For such hydrophobization, for example, the TENPO oxidation method can be used. Also, a CNF dispersion obtained by solvent substitution of the water in which CNF is dispersed is mixed with a liquid resin (for example, an epoxy resin or a vinyl chloride-based resin). Further, without disintegrating a cellulose material with water, it is directly disintegrated with an extruder, and the CNF obtained as a result of the disintegration is mixed with a thermoplastic resin. Such a mixing method can be costly (for example, labor, cost, or time). Therefore, a method of using CNF dispersed in water as it is is desirable.

[0080] Also, as described above, it is difficult to disperse CNF in a thermoplastic resin. In the case of poor dispersion, only one of the tensile elongation and tensile strength of the resulting CNF-containing thermoplastic resin can be improved.

[0081] Also, CNF is generally in a state of being dispersed in water. For example, the CNF content ratio in the CNF aqueous dispersion is about several mass%, and the water content ratio of the CNF aqueous dispersion is high. Therefore, it is often difficult to mix the CNF aqueous dispersion with a thermoplastic resin.

[0082] The plasticized starch material can easily disperse CNF in the material, and further, can easily mix the plasticized starch material containing CNF with a thermoplastic resin. Therefore, CNF can be easily dispersed in the thermoplastic resin by the plasticized starch material. By including CNF in the thermoplastic resin, the tensile physical properties and impact strength of the starch non-eluting film formed from the thermoplastic resin can be enhanced. In an embodiment where the plasticized starch material contains CNF, CNF may be added to the thermoplastic resin.

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

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

[0085] In addition, when the biomass content ratio or biodegradable resin content ratio in the thermoplastic resin increases, the tensile strength of the thermoplastic resin may decrease. By mixing the plasticized starch material containing CNF with the thermoplastic resin as described above, the problem of tensile strength reduction caused by a high biomass content ratio or biodegradable resin content ratio in the thermoplastic resin can be solved. Furthermore, other effects brought about by CNF can also be manifested in the thermoplastic resin.

[0086] Examples of the CNF contained in the plasticized starch material include CNF dispersed in water produced by the above general production method. In addition to the CNF dispersed in water, modified CNF such as the hydrophobized CNF described above may be contained in the plasticized starch material. Even powdered CNF can be dispersed in the plasticized starch material if it is dispersed in water. Thus, the plasticized starch material can disperse various CNFs in the material. Note that CNF dispersed in water is preferable as the CNF dispersed in the plasticized starch material from the viewpoints of cost and ease of handling. CNF dispersed in water is also particularly easy to introduce into the production equipment of the plasticized starch material.

[0087] Also, 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 may be dispersed 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 a combination of two or more selected from water, glycerin, ethylene glycol, propylene glycol, formamide, and urea water. The liquid may also be one or a combination of two or more of the polyhydric alcohols described above.

[0088] The thermoplastic resin for forming the starch non-eluting film according to the first embodiment may preferably contain the starch, the thermoplastic resin, the compatibilizer, and the oxidation decomposition accelerator. The composition ratios of the starch and the thermoplastic resin are, for example, preferably 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 is, for example, preferably 1 part by mass to 10 parts by mass, and more preferably 2 parts by mass 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 oxidation decomposition accelerator is, for example, preferably 0.01 part by mass to 5 parts by mass, and more preferably 0.05 part by mass 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-eluting]

[0091] The starch non-eluting film according to the first embodiment exhibits starch non-eluting property. Here, the starch non-eluting property means the property that the starch contained in the thermoplastic resin does not elute into water. The starch non-eluting property in the present embodiment may preferably mean the non-eluting property determined by the potassium permanganate consumption test.

[0092] <Potassium permanganate consumption test> The potassium permanganate consumption means the amount of potassium permanganate required to oxidize the amount of organic substances 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 in water under predetermined conditions is represented 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-elution by the potassium permanganate consumption test can be evaluated through the following operation steps. (i) Cut the film into 5 cm squares and thoroughly wash both sides with pure water. (ii) Put 100 mL of pure water into a beaker and heat the beaker in a water bath at 60 °C. (iii) Immerse the washed film in the pure water in the beaker heated in the 60 °C water bath and leave it for 30 minutes. The liquid in the beaker is used as the eluate. (iv) After 30 minutes, take out the film and filter the eluate with filter paper. The mesh of the filter paper is arbitrary. The filtered liquid is used as the filtrate. (v) Add 5 mL of commercially available sulfuric acid diluted three 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 visually compare the color difference with the blank that has gone through the above steps (i) to (v) except that the film is not immersed in the pure water in the beaker in the above step (ii). Note that the non-elution is evaluated according to the following criteria. A: There is no color difference from the blank. B: Color remains but is lighter than the blank. C: It becomes colorless.

[0094] (3) Method for manufacturing the film

[0095] The manufacturing method of the starch non-eluting film according to the first embodiment can adopt the manufacturing method of ordinary petroleum-based plastic films. For example, a first mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature, and water; a plasticized starch preparation step of plasticizing the starch by heating the mixture obtained in the first mixing step to prepare plasticized starch; and a starch-containing first resin preparation step of kneading the plasticized starch and a thermoplastic resin used as the first resin (hereinafter sometimes referred to as the first resin). And the manufacturing method may 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 and a thermoplastic resin used as the second resin (hereinafter sometimes referred to as the second resin) to prepare a starch-containing resin composition. Further, the manufacturing method may include a molding step of molding the starch-containing resin composition obtained in the starch-containing resin composition preparation step.

[0096] Also, in the starch-containing first resin preparation step, for example, first, raw materials such as starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature, water, and a thermoplastic resin may be mixed. The first resin may be provided in a pelletized form or in a powder form. The mixing of the raw materials such as the starch and the thermoplastic resin may be performed by, for example, a commercially available stirrer or a mixer such as a Henschel mixer, a tumbler-type mixer, a Brabender mixer, or a kneader mixer. The mixing of the raw materials is preferably performed at normal temperature. Further, after mixing the raw materials at normal temperature, the mixed raw materials may naturally heat up to about 40°C. The kneading of the mixed raw materials may be performed by, for example, 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 treatment by a twin-screw kneading extruder. As the twin-screw kneading extruder, a co-rotating twin-screw kneading extruder may be used, or a counter-rotating twin-screw kneading extruder may be used. By performing the kneading treatment by a twin-screw kneading extruder, a starch-containing first resin in which starch is more uniformly dispersed can be obtained.

[0097] In the step of preparing the starch-containing first resin, the first resin can be heated to a temperature at which it can be melted. The temperature may be appropriately selected by those skilled in the art according to the melting point of the first 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 can be set as appropriate.

[0098] In the step of preparing the starch-containing first resin, the starch-containing first resin may be directly fed into the molding step without being pelletized. Thereby, the pelletizing step can be omitted.

[0099] In addition, in the step of preparing the starch-containing first resin, after mixing the starch and the first resin in a mixer, strands may be extruded by a single-screw extruder or a twin-screw extruder, cut to produce pellets, and the pellets may be used as a masterbatch for the molding step.

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

[0101] In the step of preparing the starch-containing first resin, preferably 95 parts by mass or less of the first resin is blended with respect to 100 parts by mass of the starch, more preferably 90 parts by mass or less of the first resin is blended, even more preferably 85 parts by mass or less of the first resin is blended, and even more preferably 80 parts by mass or less of the first resin is blended.

[0102] In the step of preparing the starch-containing first resin, in addition to the starch and the first resin, other components may be blended. Examples of the other components include the compatibilizer, the oxidation decomposition accelerator, the colorant, and the antioxidant.

[0103] In the step of preparing the starch-containing resin composition, the thermoplastic resin corresponding to the second resin may be provided in a pelletized form or in a 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, a twin-screw kneading extruder, or the like. As these kneading extruders, devices known in the art may be used. Preferably, the step of preparing the starch-containing resin composition includes at least a kneading treatment by a twin-screw kneading extruder. As the twin-screw kneading extruder, a co-rotating twin-screw kneading extruder or a counter-rotating twin-screw kneading extruder may be used. By performing the kneading treatment by a twin-screw kneading extruder, a starch-containing resin composition in which starch is more uniformly dispersed can be obtained.

[0104] In the step of preparing the starch-containing resin composition, the second resin can be heated to a temperature at which it can be melted. The temperature may be appropriately selected by those skilled in the art according to 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 can be set as appropriate.

[0105] In the step of preparing the starch-containing resin composition, the starch-containing resin composition may be directly supplied to the molding step without being pelletized. Thereby, the pelletizing step can be omitted.

[0106] In addition, the starch-containing resin composition obtained in the step of preparing the starch-containing resin composition may be supplied to a single-screw extruder or a twin-screw extruder with the starch-containing first resin and the second resin, strands may be extruded from these extruders, cut to produce pellets, and the pellets may be used as a masterbatch in the molding step.

[0107] In the step of preparing the starch-containing resin composition, 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 is blended, still more preferably 80 parts by mass or more of the second resin is blended, and even more preferably 90 parts by mass or more of the second resin can be blended.

[0108] In the step of preparing the starch-containing resin composition, preferably 170 parts by mass or less of the second resin is blended with 100 parts by mass of the starch-containing first resin, more preferably 150 parts by mass or less of the second resin is blended, still more preferably 130 parts by mass or less of the second resin is blended, and even more preferably 120 parts by mass or less of the second resin can be blended.

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

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

[0111] When manufacturing a film, the molding temperature range to be adopted is preferably in the range of 95 to 200 °C from the viewpoints of suppressing the generation and decomposition of charring of the raw materials, seizure in the cylinder, and suppressing the discharge of starch in an unmelted state, which may cause problems with the pressure increase. Also, when manufacturing and molding pellets, it is preferably in the range of 95 to 200 °C.

[0112] Also, from the viewpoint of preventing the generation and decomposition of charring of the raw materials, the residence time in the cylinder is preferably at most 10 minutes.

[0113] The film extruded by the inflation molding machine may be cooled, taken up, and wound up while setting the temperature of the take-up roll to 90 °C or lower and forming a film with 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 of the film or both sides. Such a film may be, for example, a polyolefin resin such as polyethylene (PE resin), polypropylene (PP) resin, etc., or a combination of two or more selected from these, or, for example, polylactic acid resin (PLA), or 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), etc., or a combination of two or more selected from these polyester resins. 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 the resin used for such an adhesive layer include epoxy resin, urethane resin, etc. The starch non-eluting film and the film can be adhered via heat sealing or an adhesive layer.

[0115] (4) Use of the film

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

[0117] 2. Second Embodiment (Example of Manufacturing Method of Formed Body)

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

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

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

[0121] Hereinafter, the starch used in this step will be described.

[0122] <Starch>

[0123] Examples of the starch used in this step include underground starch and aboveground starch.

[0124] Underground starch is starch accumulated underground, for example, starch accumulated in underground stems or roots. Examples of underground starch include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, kudzu starch, and bracken starch.

[0125] Aboveground starch is starch accumulated aboveground, for example, starch accumulated in seeds. Examples of aboveground starch include, but are not limited to, corn starch, wheat starch, sago starch, acorn starch, and rice starch.

[0126] In this step, it is also possible to preferably use underground starch. 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., a modified starch), particularly a modified starch of underground starch. Examples of such modified products include physically modified starches that have been physically modified or chemically modified starches that have been chemically modified. Examples of physically modified starches include alpha starch, wet heat starch, and the like. Examples of chemically modified starches include acetoacetylated starch, acetylated starch, hydroxymethyl etherified starch, hydroxypropyl etherified starch, carboxymethyl etherified starch, allyl etherified starch, methyl etherified starch, succinylated starch, xanthan gum acetylated starch, nitrate esterified starch, urea phosphate esterified starch, phosphate esterified starch, phosphate cross-linked starch, formaldehyde cross-linked starch, acrolein cross-linked starch, epichlorohydrin cross-linked starch, and the like. The modified product can be plasticized at a lower temperature compared to unmodified starch. Therefore, it is possible to suppress the odor and / or coloring associated with heating during the production of the plasticized starch described later.

[0128] The starch preferably may contain equilibrium moisture. The amount of equilibrium moisture is, for example, preferably 10% by mass to 15% by mass, more preferably 10% by mass to 14% by mass, still more preferably 10% by mass to 13% by mass, and even more preferably 11% by mass to 13% by mass, based on the starch mass. 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 step may be plasticized. When the starch is plasticized, the particle diameter of the starch granules can be 2 μm or less. Thereby, the surface of the molded article to be molded can be smoothed, and for example, the physical properties of the molded article (such as tensile elongation) can also be improved. Plasticization of the starch can be achieved, for example, by a method of heating the starch or a method of 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.

[0130] Moreover, by using the plasticized starch (hereinafter referred to as "plasticized starch"), a molded article having good quality (for example, surface smoothness, low coloring degree, and low odor) can be produced.

[0131] In addition, by using the plasticized starch, transparency can be imparted to the molded article. Also, by using the plasticized starch, the surface of the molded article can be smoothed.

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

[0133] Hereinafter, the plasticized starch material used in this step will be described.

[0134] <Plasticized Starch Material>

[0135] The plasticized starch material may be a material mainly composed of starch. The content ratio of starch 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, based on the mass of the plasticized starch material. The content ratio of starch 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, based on the mass of the plasticized starch material. The content ratio of the starch may be measured by TG measurement (thermogravimetric analysis) at 150°C. Specifically, the content ratio may be determined based on the amount of mass change measured using a TG measurement 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 the polar organic compound capable of gelatinizing or plasticizing the starch. Therefore, the content ratio of starch in the plasticized starch material is obtained by the following formula: (Content ratio of starch in the plasticized starch material (unit: % by mass)) = (Mass after the start of measurement of the amount of mass change) / (Mass before the start of measurement of the amount of mass change) × 100. The measurement conditions for the amount of mass change are as follows: temperature range 25°C to 150°C, heating rate 20°C / min, under nitrogen.

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

[0137] The polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature refers to a polar organic compound that cannot gelatinize or plasticize the starch at room temperature but can gelatinize or plasticize the starch at a temperature higher than room temperature. In this specification, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is also referred to as "a polar organic compound capable of gelatinizing or plasticizing the starch at high temperature". For example, when the starch does not gelatinize or plasticize even after the polar organic compound and the starch are brought into contact at room temperature for 1 hour, but the starch gelatinizes or plasticizes by bringing the polar organic compound and the starch into contact at high temperature for 1 hour, the polar organic compound is "capable of gelatinizing or plasticizing the starch at high temperature". The polar organic compound capable of gelatinizing or plasticizing the starch may be any of a polar organic compound capable of gelatinizing the starch, a polar organic compound capable of plasticizing the starch, and a polar organic compound capable of both gelatinizing and plasticizing the starch.

[0138] In this specification, the temperature higher than room temperature (also referred to as "high temperature") refers to the temperature achieved by heat treatment. The high temperature can be, for example, a temperature of 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 can be, for example, less than 50°C, preferably 10 to 40°C, more preferably 15°C to 35°C, and even more preferably 20 to 30°C.

[0140] Preferably, the total content ratio of the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature in the plasticized starch material 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, based on the mass of the plasticized starch material. The total content ratio of the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature in the plasticized starch material 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, based on the mass of the plasticized starch material. The total content ratio of the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is calculated by subtracting the content ratio of the gelatinized starch measured by the TG measurement described above from 100% by mass.

[0141] In this step, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is preferably a liquid at room temperature. Thereby, mixing with starch can be easily performed.

[0142] The polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature (high temperature) constituting the plasticized starch material may contain at least one polyhydric alcohol.

[0143] The polyhydric alcohol refers to an alcohol having two or more hydroxyl groups in the 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 polyhydric alcohol preferably has 2 to 5 hydroxyl groups (OH groups), and more preferably 2 to 4 hydroxyl groups (OH groups).

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

[0145] The polyhydric alcohol may preferably contain one or a combination of two or more selected from glycerin, ethylene glycol, and propylene glycol. The plasticized starch material may contain the polyhydric alcohol in an amount of, for example, preferably 10 parts by mass to 40 parts by mass, more preferably 20 parts by mass to 35 parts by mass, based on 100 parts by mass of starch. Further, the content of the polyhydric alcohol 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 the occurrence of bleed under high-temperature and high-humidity conditions, the content of glycerin in the molded article may preferably be 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more and 9% by mass or less, and even more preferably 0% by mass or more and 7% by mass or less. The less the amount of glycerin, the more effectively the occurrence of bleed can be suppressed. Therefore, it is preferable to use other polyhydric alcohols or the like instead of glycerin without using glycerin. For example, it is preferable to use ethylene glycol or propylene glycol instead of glycerin. That is, from the viewpoint of suppressing the occurrence of bleed, it may contain only ethylene glycol or only propylene glycol, for example, without containing any glycerin.

[0147] However, the starch granules may become larger as the glycerin content decreases. Even when the glycerin content is decreased, the plasticized starch material may further contain an organic acid in order to reduce the size of the starch granules. The organic acid refers to an organic compound exhibiting acidity, and the organic compound refers to a compound having at least one carbon atom. Examples of the organic acid include carboxylic acid, sulfonic acid, sulfinic acid, organic phosphinic acid, and organic phosphonic acid.

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

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

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

[0151] It is considered that the plasticization also contributes to reducing the starch granules contained in the molded article. For example, in a molded article formed from a starch-containing resin composition containing unplasticized starch, the particles of the starch tend to appear on the surface of the molded article. The particles of the starch have a particle size of about 20 μm, for example. Therefore, when forming a film using a starch-containing resin composition containing unplasticized starch, for example, in order to prevent the particle shape of the starch from appearing on the surface of the film, the content ratio of the starch in the resin composition is limited to, for example, at most about 30% by mass based on the mass of the resin composition. Further, when the thickness of the film is about 20 μm or less, the particles of the starch are significantly shown on the film surface. Also, when trying to produce a non-woven fabric from a starch-containing resin composition containing unplasticized starch, while the thickness of the fibers forming the non-woven fabric is about 20 to 30 μm, the particle diameter of the starch becomes 20 μm, and the size of the starch granules becomes almost the same as the thickness of the fibers, and the starch granules protrude outside the fibers, causing thread breakage. On the other hand, since the starch contained in the plasticized starch material is plasticized, the particle diameter of the starch granules becomes 2 μm or less, the starch granules do not protrude outside the fibers, and thread breakage does not occur. Also, since the particle diameter of the starch granules is small, it is possible to provide a thin yarn such as a non-woven fabric or a highly transparent one. Furthermore, since the particle diameter of the starch is small, the shape of the starch is less likely to appear on the surface of the resin composition. Therefore, the content ratio of the starch in the molded article can be more than 30% by mass based on the mass of the molded article, and may be, for example, 50% or more, particularly 60% or more, and more particularly 70% or more. Even if the content ratio of the starch is high, the surface of the molded article is smooth.

[0152] Hereinafter, the first resin used in this step will be described.

[0153] <First resin>

[0154] The first resin B1 may preferably be a thermoplastic resin. The thermoplastic resin may preferably be a polyolefin-based resin or a polyester-based resin, or a mixture of these resins. The thermoplastic resin may be a polystyrene-based resin.

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

[0156] Polyethylene resins may be, for example, low-density polyethylene resins (LDPE: Low Density Polyethylene), high-density polyethylene resins (HDPE: High Density Polyethylene), very-low-density polyethylene resins (VLDPE: Very Low Density Polyethylene), linear low-density polyethylene resins (LLDPE: Linear Low Density Polyethylene), ethylene copolymers such as ethylene-vinyl acetate copolymers (EVA resins), or ultra-high molecular weight polyethylene resins (UHMW-PE: Ultra High Molecular Weight-Polyethylene), or a combination of these resins.

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

[0158] The polyolefin resin may preferably be a biomass-derived polyolefin resin (e.g., biomass-derived polyethylene resin, etc.), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. Thereby, the CO 2 emission can be reduced.

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

[0160] The polystyrene resin may also be a polystyrene resin of a metallocene catalyst system.

[0161] The polyester resin is a polymer in which monomers are polymerized by an ester bond. The polyester resin may be, 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 of these resins selected therefrom.

[0162] The polystyrene resin is a polymer in which styrene-based monomers are polymerized. The polystyrene resin may be, for example, polystyrene resin, rubber-reinforced polystyrene resin (impact-resistant polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylic acid ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, and acrylonitrile-ethylene propylene-styrene copolymer, etc., or a combination of two or more of these resins selected therefrom.

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

[0164] In this project, the first resin B1 may be a biodegradable resin. Examples of the biodegradable resin include biodegradable polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and mixtures of two or more selected from among 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] Also, in order to suppress the elution of starch into water, the SP value of the first resin B1 may be 7.8 (cal / cm) 1 / 2 or more and 11.0 (cal / cm) 1 / 2 or less. 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 contain 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 adopting a thermoplastic resin having a lower melting point, the temperature during the molding of the molded article can be lowered, and the odor or coloring caused by the heating of the starch can be more effectively suppressed.

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

[0168] In this step, preferably 30 parts by mass or more of the first resin B1 is blended with respect to 100 parts by mass of the starch, more preferably 40 parts by mass or more of the first resin B1 is blended, still 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 can be blended.

[0169] In this step, preferably 95 parts by mass or less of the first resin B1 is blended with respect to 100 parts by mass of the starch, more preferably 90 parts by mass or less of the first resin B1 is blended, still more preferably 85 parts by mass or less of the first resin B1 is blended, and even more preferably 80 parts by mass or less of the first resin B1 can be blended. By mixing at such a blending ratio, the starch granules contained in the molded body can be made smaller.

[0170] [Other components]

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

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

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

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

[0175] The olefin-based graft-modified product may be an acid-modified polyolefin, and more specifically, may be a polyolefin graft-modified with an unsaturated carboxylic acid or its derivative. Examples of the (unmodified) polyolefin used for graft modification may include polyethylene, polypropylene, or an ethylene·α-olefin copolymer (ethylene·propylene copolymer), and particularly may be polypropylene. For example, the acid-modified polyolefin described in JP-A-2010-095671 may be used.

[0176] The oxidation decomposition accelerator may be a combination of a carboxylic acid metal salt and a rare earth compound. Examples of the oxidation decomposition accelerator containing such a combination may include, for example, P-Life (manufactured by Pei Life Japan Ink Co., Ltd.).

[0177] The carboxylic acid metal salt contained in the oxidation decomposition accelerator may be, for example, a metal salt of an aliphatic carboxylic acid having 10 to 20 carbon atoms, and more preferably may be a metal salt of stearic acid. Examples of the metal atom forming the metal salt with the aliphatic carboxylic acid may include one or a combination of two or more selected from 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 may be one or a combination of two or more 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 also be used.

[0178] The rare earth compound contained in the oxidative decomposition accelerator may be, for example, an oxide of rare earth, a hydroxide of rare earth, a sulfate of rare earth, a nitrate of rare earth, an acetate of rare earth, a chloride of rare earth, or a carboxylate of rare earth. More specifically, the rare earth compound may be one or a combination of two 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 octylate, lanthanum oxide, yttrium oxide, and scandium oxide. As the rare earth compound, one type of rare earth compound may be used alone, or a combination of two or more types of rare earth compounds may be used.

[0179] As an example of the colorant, titanium oxide and / or carbon black may be used. Further, as an example of the antioxidant, a phenolic antioxidant may be used, but is not limited thereto.

[0180] In this step, preferably, it may contain the starch, the first resin B1, the compatibilizer, and the oxidative decomposition accelerator. The composition ratio of the starch and the first resin B1 is, for example, preferably 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 still more preferably 50 parts by mass:50 parts by mass to 80 parts by mass:20 parts by mass. The content of the compatibilizer is, for example, preferably 1 part by mass to 10 parts by mass, and more preferably 2 parts by mass 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 is, for example, preferably 0.01 part by mass to 7 parts by mass, and more preferably 0.05 part by mass 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 plasticizing the starch by heating the mixture obtained in the first mixing step to prepare a plasticized starch.

[0182] Also, in this process, first, raw materials such as starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, water, and a first resin B1 may be mixed. The first resin B1 may be provided in a pelletized form or in a powder form. The mixing of the raw materials such as the starch and the first resin B1 may be performed, for example, by a commercially available stirrer or a mixer such as a Henschel mixer, a tumbler-type mixer, a Barbara mixer, or a kneader mixer. The mixing of the raw materials may be performed at room temperature. Also, 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 performed, 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 treatment by a twin-screw kneading extruder. As the twin-screw kneading extruder, a co-rotating twin-screw kneading extruder or a counter-rotating twin-screw kneading extruder may be used. By performing a kneading treatment with a twin-screw kneading extruder, a starch-containing first resin in which the starch is more uniformly dispersed can be obtained.

[0183] The starch-containing first resin preparation step can be heated to a temperature at which the first resin B1 can be melted. This temperature may be appropriately selected by those skilled in the art according to the melting point of the first resin B1 used. The kneading in this step is preferably performed at 80 to 200°C, more preferably at 90 to 170°C, and even more preferably at 95 to 180°C. The kneading time can be set as appropriate.

[0184] In the starch-containing first resin preparation step, the starch-containing first resin may be directly provided to the molding step without being pelletized. Thereby, the pelletizing step can be omitted.

[0185] In the starch-containing first resin preparation step, after the starch-containing first resin is mixed with starch and the first resin B1 in a mixer, strands may be extruded by a single-screw extruder or a twin-screw extruder, cut to produce pellets, and the pellets may be used 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 respect to 100 parts by mass of the starch, more preferably 40 parts by mass or more of the first resin B1 is blended, still 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 can be blended.

[0187] In the starch-containing first resin preparation step, preferably 95 parts by mass or less of the first resin B1 is blended with respect to 100 parts by mass of the starch, more preferably 90 parts by mass or less of the first resin B1 is blended, still more preferably 85 parts by mass or less of the first resin B1 is blended, and even more preferably 80 parts by mass or less of the first resin B1 can be blended.

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

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

[0190] Hereinafter, the second resin B2 used in this step will be described.

[0191] [Second resin]

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

[0193] In the process of preparing the starch-containing resin composition, the thermoplastic resin used as the second resin B2 may preferably be a polyolefin resin or a polyester resin, or a mixture of these resins. Further, the second resin B2 may be a polystyrene resin.

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

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

[0196] As such a polyethylene resin, preferably, it may be a low-density polyethylene resin (LDPE), a high-density polyethylene resin (HDPE), a very-low-density polyethylene resin (VLDPE), a linear low-density polyethylene resin (LLDPE), or a combination of these resins.

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

[0198] The polyolefin resin may preferably be a polyolefin resin derived from biomass (such as a polyethylene resin derived from biomass), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. Thereby, the CO2 emission can be reduced.

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

[0200] In this step, the second resin B2 may be a biodegradable resin. Examples of the biodegradable resin include biodegradable polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and mixtures of two or more selected from among the 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] Also, in order to suppress the elution of starch from the molded molded article into water, the SP value of the second resin B2 may be 7.7 (cal / cm) 1 / 2 or more and 8.4 (cal / cm) 1 / 2 or less.

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

[0203] As shown in the above relational expression, the absolute value of the difference between the SP value of the second resin B2 and the SP value of water, which is 23.4 (cal / cm) 1 / 2 is preferably larger than the absolute value of the difference between the SP value of the first resin B1 and the SP value of water, which is 23.4 (cal / cm) 1 / 2 That is, it is preferable that the second resin B2 has lower hydrophilicity than the first resin B1. Since the second resin B2 used in this step has lower hydrophilicity than the first resin B1, in the starch-containing first resin preparation step, the starch is coated with the first resin B1, and further, the starch is coated with the second resin B2 having lower hydrophilicity than the first resin B1 in this step, so that the elution of the starch contained in the starch-containing first resin into water can be suppressed.

[0204] The second resin B2 may be in the form of pellets or powder, and is mixed, kneaded, and uniformly dispersed during molding by a single-screw extruder, a twin-screw extruder, an injection molding machine, or the like.

[0205] In this step, from the viewpoint of diluting the starch concentration in the starch-containing first resin, the second resin B2 is preferably mixed with the starch-containing first resin in a blending amount of 60 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more, based on 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 a blending amount of preferably 170 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less, based on 100 parts by mass of the starch-containing first resin.

[0207] <Other components>

[0208] In this process, in addition to the starch-containing first resin and the second resin B2, other components may be blended. Examples of such other components include compatibilizers, oxidative degradation 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] Hereinafter, the compatibilizer used in this process will be described.

[0211] <Compatibilizer>

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

[0213] The carboxylic anhydride constituting the carboxylic anhydride-modified polyolefin may preferably be maleic anhydride. The compatibilizer may be, for example, one or a combination of two or more selected from the group consisting of 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, may be a polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. Examples of the (unmodified) polyolefin used for graft modification may include polyethylene, polypropylene, or an ethylene·α-olefin copolymer (ethylene·propylene copolymer), and particularly may be polypropylene. For example, the acid-modified polyolefin described in JP-A-2010-095671 may be used.

[0215] In this process, the compatibilizer can be mixed with the starch-containing first resin in a blending amount of preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, based on 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 still more preferably 95 to 180 °C. The mixing time can be set as appropriate.

[0217] [Forming body forming step]

[0218] In the forming body forming step, the starch-containing resin composition is formed to obtain a starch non-eluting forming body.

[0219] In the forming body forming step, the starch-containing resin composition may be formed into a forming body by a forming method such as inflation molding using an inflation molding machine, T-die molding using a T-die extruder, calendar molding using a calendar molding machine, or injection molding using an injection molding machine.

[0220] In the above various molding machines, the starch-containing resin composition is heated and melted to the molding temperature, extruded from the die or nozzle of the molding machine, and cooled to produce a molding body. The adopted molding temperature range is above the melting points of the first resin B1 and the second resin B2. When directly kneading, mixing, and molding the raw materials, from the viewpoints of suppressing the occurrence of scorching, decomposition of the raw materials, and sticking in the cylinder of the molding machine, and suppressing the starch from being discharged in an unmelted state and causing problems with the pressure increase, it is preferably in the range of 95 to 200 °C. Also, from the viewpoint of preventing the occurrence of scorching and decomposition of the raw materials, the residence time of the starch-containing resin composition in the cylinder of the molding machine is preferably within 10 minutes at most.

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

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

[0223] A film refers to a thin film-like object, and the thickness of the film is, for example, less than 200 μm, and particularly may be 10 μm or more and less than 200 μm. A sheet refers to a thin plate-like object, and the thickness of the sheet is, for example, less than 200 μm, and particularly may be 10 μm or more and less than 200 μm.

[0224] Also, in the molded body forming step, the starch-containing resin composition may be formed into, for example, a food packaging bag, a shopping bag, a garbage collection bag, an agricultural bag, a container (for example, a bottle container), a bottle cap, or a plastic drum by a molding method such as blow molding, injection molding, or profile extrusion molding. 3. Examples

[0225] Hereinafter, the present invention will be described in more detail based on examples. Note that the examples described below show an example of typical examples of the present invention, and the scope of the present invention is not limited only to these examples. In the examples, the evaluation methods and evaluation criteria used are as follows.

[0226] (1) Potassium permanganate consumption test The measurement of the potassium permanganate consumption was carried out according to the following operation steps. (i) The film was cut into 5 cm squares and both sides were thoroughly washed with pure water. (ii) Pour 100 mL of pure water into a beaker and heat the beaker in a water bath at 60 °C. (iii) Immerse the washed film in the pure water in the beaker heated in a water bath at 60 °C and leave it for 30 minutes. The liquid in the beaker was used as the eluate. (iv) After 30 minutes, take out the film and filter the eluate with filter paper. The mesh of the filter paper was arbitrary. The filtered liquid was used as the filtrate. (v) Add 5 mL of commercially available sulfuric acid diluted three 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 visually with the blank that has gone through the above steps (i) to (v) except that the film is not immersed in the pure water in the beaker in the above step (ii). Note that non-elution was evaluated according to the following criteria. A: There is no color difference from the blank. B: Color remains, but it is lighter than the blank. C: It becomes colorless.

[0227] Test Example 1: Production of Film

[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 volume of glycerin, and 27 parts by mass of water were prepared as the plasticized starch material. These three components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin and the water were premixed before being put into the mixer.

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

[0231] The mixture obtained by the mixing was supplied into a twin-screw extruder (PCM30, Ikegai Corporation) and the mixture was subjected to kneading treatment.

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

[0233] 50 parts by mass of the plasticized starch of Example 1, 50 parts by mass of ethylene-vinyl acetate copolymer (750, manufactured by Tosoh Corporation, SP value: 9.1 (cal / cm) 1 / 2 ) as the first resin B1, 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 a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing first resin (hereinafter, also referred to as "starch-containing first resin of Example 1") was obtained.

[0234] 60 parts by mass of the starch-containing first resin of Example 1, 40 parts by mass of 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 / 2 ) as the second resin B2, 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 a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "starch-containing resin composition of Example 1") was obtained. In the starch-containing resin composition of Example 1, 30 parts by mass of plasticized starch was blended.

[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. By this inflation molding, a film with a thickness of 40 μm was obtained.

[0236] A potassium permanganate consumption test was conducted on the film, and the non-elution elution property of starch was evaluated according to the above method and criteria. The evaluation results are as shown in Table 1 below. The film had an extremely 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.

[0237]

Table 1

[0238] (Example 2)

[0239] In the same manner as in Example 1, elongated substantially columnar plasticized starch (hereinafter, also referred to as "plasticized starch (masterbatch) of Example 2") was obtained.

[0240] As shown in Table 1 above, instead of the ethylene-vinyl acetate copolymer (750, Tosoh Corporation) as the first resin in the twin-screw extruder, 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 / 2)A 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.

[0241] 60 parts by mass of the starch-containing first resin of Example 2, 40 parts by mass of 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 / 2 )as the second resin, and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were fed into a twin-screw extruder (PCM30, Ikegai Corporation), and these components were subjected to a kneading process. The screw temperature in the kneading process was 170 °C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter also referred to as "the starch-containing resin composition of Example 2") was obtained. In the starch-containing resin composition of Example 2, 30 parts by mass of plasticized starch was blended.

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

[0243] Also in Example 2, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. It was a film with less starch soluble in water.

[0244] (Example 3)

[0245] As shown in Table 1 above, 100 parts by mass of phosphoric acid-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 plasticized starch material. These four components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and the water were premixed before being put into 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 a kneading process.

[0248] The cylinder temperature in the kneading process was 110°C. In the kneading process, suction from the vent was performed. After the kneading process, 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 ) 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 a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.2 MPa. In the kneading process, suction from the vent was performed. By the kneading process, 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 as the second resin, 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 / 2)40 parts by mass and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, manufactured by Ikegai Corporation), and these components were subjected to a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "the starch-containing resin composition of Example 3") was obtained. In the starch-containing resin composition of Example 3, 30 parts by mass of plasticized starch was blended.

[0251] The starch-containing resin composition of Example 3 was supplied to an inflation molding machine (manufactured by 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 the inflation molding, a film with a thickness of 40 μm was obtained.

[0252] Also in Example 3, the same evaluation as in Example 1 was performed. 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 And 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 It was.

[0253] (Example 4)

[0254] As shown in Table 1 above, 100 parts by mass of phosphoric acid-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 plasticized starch material. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and the water were premixed before being charged into the mixer.

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

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

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

[0258] 50 parts by mass of the plasticized starch of Example 4, 50 parts by mass 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 ) 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 a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.2 MPa. In the kneading process, suction from the vent was carried out. By the kneading process, a starch-containing first resin (hereinafter, also referred to as "starch-containing first resin of Example 4") was obtained. In the starch-containing resin composition of Example 4, 30 parts by mass of plasticized starch was blended.

[0259] 60 parts by mass of the starch-containing first resin of Example 4, 40 parts by mass of 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 / 2 ) 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 a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "the starch-containing resin composition of Example 4") was obtained.

[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. By the inflation molding, a film with a thickness of 40 μm was obtained.

[0261] Also in Example 4, the same evaluation as in Example 1 was performed. The evaluation results are as shown in Table 1 above. It was a film with a small amount of starch dissolved in water.

[0262] (Example 5)

[0263] As shown in Table 1 above, 100 parts by mass of a phosphoric acid-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 a plasticized starch material. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, ethylene glycol, and the water were premixed before being charged into the mixer.

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

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

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

[0267] 70 parts by mass of the plasticized starch of Example 5, 30 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 fed into a twin-screw extruder (PCM30, Ikegai Corporation), and these components were subjected to a kneading process. The screw temperature in the kneading process was 170 °C, and the resin pressure was 4.2 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing first resin (hereinafter, also referred to as "starch-containing first resin of Example 5") was obtained.

[0268] 45 parts by mass of the starch-containing first resin of Example 5, 50 parts by mass of 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 / 2 ) as the second resin, and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were fed into a twin-screw extruder (PCM30, Ikegai Corporation), and these components were subjected to a kneading process. The screw temperature in the kneading process was 170 °C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "starch-containing resin composition of Example 5") was obtained. In the starch-containing resin composition of Example 5, 30 parts by mass of plasticized starch was blended.

[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) as the second resin 1 / 2)70 parts by mass and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, manufactured by Ikegai Corporation), and these components were subjected to a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "the starch-containing resin composition of Comparative Example 1") was obtained. In the starch-containing resin composition of Comparative Example 1, 30 parts by mass of plasticized starch was blended.

[0273] The starch-containing resin composition of Comparative Example 1 was supplied to an inflation molding machine (manufactured by 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 the inflation molding, a film with a thickness of 40 μm was obtained.

[0274] Also in Comparative Example 1, the same evaluation as in Example 1 was performed. The evaluation results are as shown in Table 1 above. It was a film with an extremely large amount of starch dissolved in water.

[0275] (Comparative Example 2)

[0276] In Comparative Example 2, without preparing the starch-containing first resin, 30 parts by mass of the plasticized starch of Example 5 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 / 2)70 parts by mass and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, manufactured by DuPont) were supplied into a twin-screw extruder (PCM30, manufactured by Ikegai Corporation), and these components were subjected to a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "the starch-containing resin composition of Comparative Example 2") was obtained. In the starch-containing resin composition of Comparative Example 2, 30 parts by mass of plasticized starch was blended.

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

[0278] Also in Comparative Example 2, the same evaluation as in Example 1 was performed. The evaluation results are as shown in Table 1 above. It was a film with a very large amount of starch dissolved in water.

[0279] (Summary of evaluation results)

[0280] Examples 1 to 5 had a small elution amount of starch in water and were films suitable for primary packaging of foods. On the other hand, Comparative Examples 1 and 2 had a large elution amount of starch in water and were not films suitable for primary packaging of foods.

[0281] (Example 6)

[0282] As a plasticized starch material, 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 performed at room temperature. The glycerin, ethylene glycol, and the water were premixed before being charged into the mixer.

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

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

[0285] The cylinder temperature in the kneading process was 110°C. In the kneading process, suction from the vent was performed. After the kneading process, 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 6") was obtained.

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

[0287] 60 parts by mass of the starch-containing first resin of Example 6, 40 parts by mass of the biodegradable resin PBAT (product name: Ecoflex (registered trademark), manufactured by BASF Japan Ltd., SP value: 10.7 (cal / cm) 1 / 2 ) 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 a kneading process. The screw temperature in the kneading process was 170°C, and the resin pressure was 4.4 MPa. In the kneading process, suction from the vent was performed. By the kneading process, a starch-containing resin composition (hereinafter, also referred to as "the starch-containing resin composition of Example 6") was obtained. In the starch-containing resin composition of Example 6, 30 parts by mass of plasticized starch was blended.

[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. By this inflation molding, a film with a thickness of 40 μm was obtained.

[0289] Also in Example 6, the same evaluation as in Example 1 was performed. It was a film with a small amount of starch dissolved in water.

[0290] As described above, the embodiments and examples of the present technology have been specifically described. However, the present technology is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present technology are possible.

[0291] For example, the configurations, methods, processes, shapes, materials, and numerical values etc. mentioned in the above-described embodiments and examples are merely examples, and different configurations, methods, processes, shapes, materials, and numerical values etc. may be used as necessary. Also, the chemical formulas of compounds etc. are representative, and as long as they are the general names of the same compounds, they are not limited to the valences etc. described.

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

[0293] Also, in this specification, the numerical range indicated using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a certain step's numerical range may be replaced with the upper limit value or the lower limit value of another step's numerical range. The materials exemplified in this specification can be used alone or in combination of two or more kinds unless otherwise specified.

Claims

1. A starch-non-eluting film formed from a starch-containing resin composition comprising a starch-containing first resin including plasticized starch, a first resin being ethylene-vinyl acetate copolymer (EVA), and a compatibilizer being a carboxylic acid anhydride-modified polyolefin, a second resin different from the first resin, and a carboxylic acid anhydride-modified polyolefin (excluding the carboxylic acid anhydride-modified polyolefin contained in the starch-containing first resin), The plasticized starch contains at least one of glycerin and ethylene glycol, and water; The non-starch dissolving property of the non-starch dissolving film is determined by a potassium permanganate consumption test for evaluating the dissolution of starch contained in the film into water.

2. A non-starch dissolving film as described in claim 1, wherein the glycerin is contained in the plasticized starch in an amount of 10 to 40 parts by mass per 100 parts by mass of the starch.

3. The non-starch extractable film according to claim 1 or 2, wherein the starch is corn starch and / or tapioca starch.

4. The non-starch dissolving film according to any one of claims 1 to 3, wherein the second resin is a polyethylene resin.

5. The non-starch dissolving film according to any one of claims 1 to 4, wherein the non-starch dissolving film is used for food packaging.

6. A non-starch dissolving film described in any one of claims 1 to 5, wherein at least one of the starch-containing first resin and the second resin comprises a biodegradable resin.

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