Resin composition and method for producing the same, plasticized starch and method for producing the same

Abstract

To provide new means for providing a plastic molding containing starch grains having small particle diameters.SOLUTION: A resin composition contains a plasticized starch material and a thermoplastic resin, in which the plasticized starch material contains starch, a polar organic compound that allows the starch to be gelatinizable or plasticizable at a temperature higher than an ordinary temperature, and water, in which particle diameters of starch grains contained in the resin composition are 2 μm or smaller. Plasticized starch has a plasticized starch material containing starch, a polar organic compound that allows the starch to be gelatinizable or plasticizable at a temperature higher than an ordinary temperature, and water. A method for producing a resin composition includes: a first mixing step of mixing starch with a polar organic compound that allows the starch to be gelatinizable or plasticizable at a temperature higher than an ordinary temperature, and water; a plasticized starch preparation step of plasticizing the starch by heating the mixture obtained in the first mixing step, and preparing plasticized starch; and a second mixing step of mixing the plasticized starch and a thermoplastic resin, and obtaining a resin composition containing starch grains having particle diameter of 2 μm or smaller.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition, a method for producing the same, a plasticized starch, and a method for producing the same.

Background Art

[0002] Conventional plastic molded articles are difficult to decompose in the natural environment after being discarded, and are 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 as such materials, plastic molded articles containing biomass materials have attracted attention. Since the plastic molded article contains a biomass material 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 flour, rice straw, bamboo, and old rice.

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

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-521181 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] However, when using a starch-based polymer material as a biomass material, it has been difficult to reduce the starch grains contained in plastic molded products depending on the conditions. When the starch grains cannot be reduced, there is a problem that molding cannot be performed, and there is also a problem that a plastic molded product having excellent physical properties cannot be manufactured. An object of the present invention is to provide a new means for providing a plastic molded product containing starch grains with a small particle size. Furthermore, an object of the present invention is to provide a new means for providing a plastic molded product capable of suppressing bleeding of various additives and the like present inside to the surface even under high-temperature and high-humidity conditions. Further, an object of the present invention is to provide a new means for providing a plastic molded product imparted with functions such as a deodorizing function and an anti-odor function. [Means for Solving the Problems]

[0006] The present inventors have found that a specific plasticized starch material can reduce the particle size of starch grains and can provide a plastic molded product capable of suppressing bleeding out of various additives and the like present inside to the surface even under high-temperature and high-humidity conditions.

[0007] That is, the present invention provides a resin composition containing a plasticized starch material and a thermoplastic resin, wherein the plasticized starch material contains starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water, and the particle diameter of the starch grains contained in the resin composition is 2 μm or less. The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature may contain at least one polyhydric alcohol. The resin composition may have a glycerin content of 0% by mass or more and 10% by mass or less. The polyhydric alcohol may contain at least one of ethylene glycol and propylene glycol. The resin composition may further contain an organic acid. The plasticized starch material may be a plasticized product of starch or a plasticized product of modified starch. The thermoplastic resin may be a polyolefin resin, a polyester resin, a polystyrene resin, or a mixture of these resins. The resin composition may further contain cellulose nanofibers. The resin composition is formed into a film, sheet, or non-woven fabric. The resin composition is formed into a film or sheet, and the surface of the film or sheet is coated with a film to form a laminate.

[0008] The present invention also provides a plasticized starch having a plasticized starch material containing starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature, and water. The present invention provides a plasticized starch having no foamed portion. The present invention provides a plasticized starch used for producing a plasticized starch-containing resin composition containing starch grains having a particle diameter of 2 μm or less. The present invention provides a plasticized starch having a hardness of 20 or more according to the durometer type D. The present invention provides a plasticized starch having a shape that is cylindrical (strand) or pellet-shaped.

[0009] The present invention includes 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 a plasticized starch, and a second mixing step of mixing the plasticized starch and a thermoplastic resin to obtain a resin composition containing starch grains having a particle diameter of 2 μm or less, and provides a method for producing a resin composition. The present invention provides a method for producing a resin composition, including a mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, water, and a thermoplastic resin, and a heating step of heating the mixture obtained in the mixing step to plasticize the starch and obtain starch granules having a particle diameter of 2 μm or less.

[0010] The present invention provides a method for producing plasticized starch, including a mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, and water, and a plasticizing step of plasticizing the starch by heating the mixture obtained in the mixing step.

[0011] The present invention further provides the above resin composition containing a functional agent. The functional agent can be at least one selected from a single substance or a composite of an antibacterial agent, a deodorant, and an anti-odor agent.

[0012] The present invention further provides the above plasticized starch containing a functional agent.

[0013] The present invention provides a method for producing the above resin composition, further including mixing a functional agent in the first mixing step.

[0014] The present invention provides a method for producing the above resin composition, further including mixing a functional agent in the mixing step.

[0015] The present invention provides a method for producing the above plasticized starch, further including mixing a functional agent in the mixing step.

Advantages of the Invention

[0016] According to the present invention, the starch granules in the plastic molded article can be made smaller. Further, bleeding out from the surface of the plastic molded article can be suppressed even under high temperature and high humidity conditions. Also, according to the present invention, functions such as deodorization and anti-odor can be imparted to the plastic molded article. Note that the effects of the present invention are not necessarily limited to the effects described herein, and may be any of the effects described in this specification.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0018] Hereinafter, the modes for carrying out the present invention will be described in detail. Note that the embodiments described below show examples of typical embodiments of the present invention, and the present invention is not limited only to these embodiments.

[0019] 1. Resin Composition

[0020] The resin composition of the present invention contains a plasticized starch material and a thermoplastic resin. The plasticized starch material contains starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water, and the particle diameter of the starch granules contained in the resin composition is 2 μm or less.

[0021] The resin composition of the present invention contains the plasticized starch material 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 even more preferably in a ratio of 15 parts by mass: 75 parts by mass to 70 parts by mass: 30 parts by mass. The resin composition having such a ratio can reduce the starch granules contained in the plastic molded product.

[0022] The starch that constitutes the plasticized starch material is plasticized. As a result, the surface of the molded article formed from the resin composition can be smoothed. Further, for example, the physical properties (such as tensile elongation) of a film or sheet formed from the resin composition, or the physical properties of a non-woven fabric can also be improved.

[0023] Further, by using the plasticized starch material, molded articles (such as films and sheets, and non-woven fabrics) having good quality (such as surface smoothness, low coloration degree, and low odor) can be manufactured. For example, since the particle diameter of the starch grains contained in the resin composition of the present invention is 2 μm or less, even when a thin film or sheet or a non-woven fabric is formed from the resin composition, the shape of the starch grains does not appear on the surface. For example, even if the starch content ratio of the resin composition of the present invention is increased, the film or sheet or non-woven fabric formed from the resin composition does not have the shape of starch grains on its surface.

[0024] Further, since the resin composition of the present invention contains the plasticized starch material, transparency can be imparted to the resin composition and the molded article (such as a film or sheet, or a non-woven fabric) formed from the resin composition. Further, since the resin composition of the present invention contains the plasticized starch material, the surface of the resin composition and the molded article (such as a film or sheet, or a non-woven fabric) formed from the resin composition can also be smoothed.

[0025] The resin composition of the present invention contains the plasticized starch material and the thermoplastic resin as main components. The total content ratio of the plasticized starch material and the thermoplastic resin in the resin composition of the present invention is, for example, preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 30% by mass or more, and even more preferably 50% by mass or more with respect to the total amount of the resin composition.

[0026] Hereinafter, the resin composition of the present invention will be described in more detail.

[0027] [Plasticized Starch Material]

[0028] By using the plasticized starch material in a resin composition, excellent moldability can be achieved when manufacturing a plastic molded article from the resin composition. Also, the physical properties of the plastic molded article can be improved. For example, when the content ratio of a known starch material (e.g., an ungelatinized starch material, etc.) in a resin composition is 50% by mass or more, molding using the resin composition may not be possible, or even if molding is possible, the molded article may not have good quality. Specifically, when inflation molding is performed using the resin composition, the resin composition may not expand, or foaming may occur in the resin composition. Furthermore, even if it expands, since the stretchability of the film obtained by the molding is poor, the film may be easily torn and may not have excellent strength. Also, when a nonwoven fabric is manufactured by the spunbond method or the meltblown method using the resin composition, it may not be possible to obtain a nonwoven fabric due to yarn breakage, and even if a nonwoven fabric is obtained, since the strength of the yarn obtained by the spinning is low, it may not be possible to obtain a strong nonwoven fabric.

[0029] Since the resin composition of the present invention contains the plasticized starch material, it has excellent moldability and is suitable for forming, for example, a film or a sheet. That is, the resin composition of the present invention can be used for forming a film or a sheet. Also, since the resin composition of the present invention contains the plasticized starch material, it has excellent physical properties (e.g., tensile elongation, etc.). Furthermore, since the resin composition of the present invention contains the plasticized starch material, it has excellent spinnability and is suitable for manufacturing, for example, a nonwoven fabric. That is, the resin composition of the present invention can be used for manufacturing a nonwoven fabric. Also, since the resin composition of the present invention contains the plasticized starch material, it has excellent physical properties (e.g., tensile strength, etc.).

[0030] In addition, the plasticized starch material used in the present invention does not have foamed portions. Such foaming may occur, for example, due to the evaporation of volatile components during the production of the plasticized starch material. A resin composition produced using a plasticized starch material having foamed portions may have poor moldability and spinnability, and furthermore, the appearance of the resin composition may deteriorate.

[0031] The plasticized starch material contained in the resin composition of the present invention 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 total amount 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 total amount 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 decrease amount of volatile components, and the decrease 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: 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 for the mass change amount are as follows: temperature range 25°C to 150°C, heating rate 20°C / min, under nitrogen.

[0032] In this specification, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than normal temperature refers to a polar organic compound that can gelatinize or plasticize the starch by contacting the starch at a temperature higher than normal temperature. As the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than normal temperature, organic compounds known in the art may be used.

[0033] 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 with each other at room temperature for 1 hour, but the starch gelatinizes or plasticizes when the polar organic compound and the starch are brought into contact with each other 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. 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. 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.

[0034] 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 total amount 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 total amount 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.

[0035] In one embodiment of the present invention, 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.

[0036] 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.

[0037] In the present invention, 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). The polyhydric alcohol may include, for example, glycerin and glycol. Examples of the glycol include ethylene glycol and propylene glycol. The polyhydric alcohol preferably may contain one or a combination of two or more selected from glycerin, ethylene glycol, and propylene glycol. The plasticized starch material of the present invention 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, per 100 parts by mass of starch. Further, the content of the polyhydric alcohol in the resin composition is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more.

[0038] From the viewpoint of suppressing the occurrence of bleed under high-temperature and high-humidity conditions, the content of glycerin in the resin composition is preferably 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 another polyhydric alcohol 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.

[0039] However, the starch granules may become larger as the glycerin content decreases. Even when the glycerin content is decreased, the resin composition of the present invention may further contain an organic acid in order to reduce 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.

[0040] 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.

[0041] In one embodiment of the present invention, the plasticized starch material contains 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.

[0042] The plasticized starch material is a starch material gelatinized or plasticized by heating starch 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 brought about, 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 material may be, for example, pregelatinized starch. It is considered that the plasticization contributes to imparting transparency and / or smoothness to the resin composition of the present invention.

[0043] It is considered that the plasticization also contributes to reducing the starch granules contained in the molded article formed from the resin composition of the present invention. For example, in a molded article formed from a 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, for example, a particle size of about 20 μm. Therefore, for example, when forming a film using a resin composition containing unplasticized starch, 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 total amount of the resin composition. Further, when the thickness of the film is about 20 μm or less, the particles of the starch are significantly manifested on the film surface. Further, when attempting to manufacture a non-woven fabric from a 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 is 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 resin composition of the present invention 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. Further, since the particle diameter of the starch granules is small, it is possible to provide thin yarns such as non-woven fabrics and those with high transparency. 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 resin composition of the present invention can be more than 30% by mass based on the total amount of the resin composition, and can be, for example, 50% or more, particularly 60% or more, and more particularly 70% or more. Even when the content ratio of the starch is high, the surface of the resin composition or the molded article is smooth.

[0044] Examples of the starch used in the present invention include underground starch and aboveground starch. Underground starch is starch accumulated underground, and refers to, 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. The above-ground starch is starch accumulated above ground, for example, starch accumulated in seeds and the like. Examples of above-ground starch include, but are not limited to, corn starch, wheat starch, sago starch, chestnut starch, and rice starch. In the present invention, preferably, underground starch is used. By producing the resin composition of the present invention using underground starch, the odor of the resin composition can be further reduced. The starch used in the present invention may be a modified starch (i.e., modified starch), particularly a modified 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, and the like. Also, examples of chemically modified starch include, for example, acetatoacetate esterified starch, acetate esterified starch, hydroxymethyl etherified starch, hydroxypropyl etherified starch, carboxymethyl etherified starch, allyl etherified starch, methyl etherified starch, succinate esterified starch, xanthan acetate esterified starch, nitrate esterified starch, urea phosphate esterified starch, phosphate esterified starch, phosphate crosslinked starch, formaldehyde crosslinked starch, acrolein crosslinked starch, epichlorohydrin crosslinked starch, and the like. The modified product 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 can be suppressed.

[0045] The starch used in the present invention 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. It is preferable to use starch or modified starch containing equilibrium moisture within the above numerical range to produce a plasticized starch material according to the present invention. When starch not containing equilibrium moisture is used, the starch may not be plasticized.

[0046] According to one embodiment of the present invention, the plasticized starch material may include a plasticized product of starch or a plasticized product of modified starch. For example, the starch may be corn starch or tapioca starch. More preferably, the plasticized starch is 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 plasticized product of the modified combination of 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 preferred from the viewpoints of reducing the odor of the plasticized starch material and reducing the odor of the resin composition of the present invention.

[0047] According to one embodiment of the present invention, the plasticized starch material may contain cellulose nanofibers (hereinafter also referred to as CNF). It is often difficult to disperse CNF in a thermoplastic resin. The plasticized starch material can easily disperse CNF in the material, and further, the plasticized starch material containing CNF and the thermoplastic resin can be easily mixed. Therefore, CNF can be easily dispersed in the thermoplastic resin by the plasticized starch material. When the resin composition of the present invention contains CNF, the tensile physical properties and impact strength of the molded product formed from the resin composition can be enhanced. In the embodiment where the plasticized starch material contains CNF, CNF may be added to the thermoplastic resin.

[0048] The merits of the plasticized starch material containing CNF will be described in more detail below. CNF is hydrophilic. Since CNF is generally produced by nanofibrillating a cellulose material with water, it is dispersed in water. CNF is used, for example, to enhance the strength of thermoplastic resins. However, since thermoplastic resins are often hydrophobic, it can be difficult to mix hydrophilic CNF with thermoplastic resins. Therefore, for example, modified and hydrophobized CNF (particularly powdered CNF) is mixed with thermoplastic resins. 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, instead of crushing a cellulose material with water, it is directly crushed with an extruder, and the CNF obtained as a result of the crushing is mixed with a thermoplastic resin. Such mixing methods can be costly (for example, labor, cost, or time). Therefore, a method of using CNF as it is dispersed in water is desirable. 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. 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, mixing the CNF aqueous dispersion with a thermoplastic resin often involves difficulties. As described above, the plasticized starch material used in the present invention can easily disperse CNF in the material, and further, the plasticized starch material containing CNF and a thermoplastic resin can be easily mixed. As the CNF, CNF dispersed in water can be used. Even when an aqueous dispersion of CNF is used, by using the aqueous dispersion of CNF in the production of the plasticized starch material, CNF can be easily dispersed in a thermoplastic resin without using the mixing method described above. Also, when the plasticized starch material containing CNF is mixed with a thermoplastic resin, CNF is well dispersed in the thermoplastic resin. Therefore, both the tensile elongation and tensile strength of the thermoplastic resin can be improved. In addition, when the biomass content ratio or biodegradable resin content ratio in the resin composition is increased, the tensile strength of the resin composition may decrease. By mixing the plasticized starch material containing CNF with a thermoplastic resin as described above, the problem of a decrease in tensile strength caused by a high biomass content ratio or biodegradable resin content ratio in the resin composition can be solved. Furthermore, other effects brought about by CNF can also be exhibited in the resin composition. 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. Powdered CNF can also be dispersed in the plasticized starch material by dispersing it 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 particularly easy to introduce into the production equipment of the plasticized starch material. In addition, 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 be one or a combination of two or more of the polyhydric alcohols described above.

[0049] In the present invention, commercially available CNF may be used. In the present invention, CNF can mean fibrous cellulose having an average fiber diameter of 10 nm to 3000 nm, which is poorly soluble in a solvent, unlike molecular cellulose. 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 average fiber length and the average fiber diameter are average values of any 10 cellulose fibers observed with an electron microscope.

[0050] The plasticized starch material may be produced by the production method described below.

[0051] [Thermoplastic resin]

[0052] The thermoplastic resin contained in the resin composition of the present invention may preferably be a polyolefin resin or a polyester resin, or a mixture of these resins. The thermoplastic resin may be a polystyrene resin.

[0053] The polyolefin resin is a polymer obtained by polymerization using olefins (for example, α-olefins) as a main monomer. The polyolefin resin may be, for example, a polyethylene (PE) resin or a polypropylene (PP) resin, or a combination thereof. The polyethylene resin may be, for example, low density polyethylene resin (LDPE), high density polyethylene resin (HDPE), very low density polyethylene resin (VLDPE), linear low density polyethylene resin (LLDPE), or ultra high molecular weight polyethylene resin (UHMW-PE), or a combination thereof. The polypropylene resin may be, for example, a homopolymer polypropylene resin, or a random copolymer or block copolymer polypropylene resin (such as an ethylene-propylene copolymer, etc.), or a combination thereof. The polyolefin resin may preferably be a polyolefin resin derived from biomass (such as a polyethylene resin derived from biomass, etc.), and may be, for example, a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. Thereby, the CO2 emissions can be reduced. 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 polypropylene resin of a metallocene catalyst system, or a combination thereof. The polystyrene resin may also be a polystyrene resin of a metallocene catalyst system.

[0054] 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.

[0055] 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.

[0056] The type of the thermoplastic resin constituting the resin composition of the present invention may be appropriately selected by those skilled in the art according to, for example, the type of the molded article formed from the resin composition, but a thermoplastic resin having a low processing temperature is preferred. For example, when forming a film or a sheet from the resin composition, the thermoplastic resin is, for example, preferably a polyolefin resin, more preferably a polyethylene resin or a polypropylene resin, and even more preferably LLDPE or LDPE. Even when the resin composition of the present invention is heated to the melting points of these resins, odor or coloring caused by heating of the plasticized starch material is unlikely to occur. Therefore, generation of odor or coloring can be suppressed when the resin composition is heated to produce a molded article.

[0057] The thermoplastic resin contained in the resin composition of the present invention 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 molding can be lowered, and the odor or coloring caused by heating of the plasticized starch material can be more suppressed.

[0058] The thermoplastic resin may be in the form of pellets or powder, and is mixed, kneaded, and uniformly dispersed during molding by an extruder, injection molding, or the like.

[0059] The resin composition of the present invention contains a plasticized starch material and a thermoplastic resin, for example, preferably in a ratio of 20 parts by mass:80 parts by mass to 80 parts by mass:20 parts by mass, more preferably in a ratio of 30 parts by mass:70 parts by mass to 80 parts by mass:20 parts by mass, still more preferably in a ratio of 40 parts by mass:60 parts by mass to 80 parts by mass:20 parts by mass, and even more preferably may be in a ratio of 50 parts by mass:50 parts by mass to 80 parts by mass:20 parts by mass. By using the plasticized starch material, even if the biomass content ratio of the resin composition of the present invention is increased as described in the above numerical range, a molded product having good quality can be produced from the resin composition.

[0060] According to one embodiment of the present invention, the thermoplastic resin may be a biodegradable resin. In this embodiment, both the plasticized starch material and the thermoplastic resin are biodegradable. Therefore, the resin composition according to this embodiment is more environmentally friendly.

[0061] [Other components]

[0062] The resin composition of the present invention may contain other components in addition to the plasticized starch material and the thermoplastic resin. Examples of the other components include a compatibilizer, an oxidation decomposition accelerator, a colorant, and an antioxidant.

[0063] The compatibilizer may be used to further improve the compatibility between the plasticized starch material and the thermoplastic resin. Examples of the compatibilizer include, for example, anhydrous carboxylic acid-modified polyolefins, olefin-based graft-modified products, and olefin-based comonomers. The anhydrous carboxylic acid constituting the anhydrous carboxylic acid-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. 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, for example, 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.

[0064] 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.

[0065] In addition to the compatibilizer, the oxidation decomposition accelerator, the colorant, and the antioxidant, the resin composition of the present invention may contain a functional agent. As used herein, the functional agent means any material that imparts a function to the resin composition and a molded article formed from the resin composition. Examples of such functional agents include antibacterial agents, disinfectants, bacteriostatic agents, fungicides, antifungal agents, deodorants, and anti-odor agents. The functional agent may be at least one selected from a single substance or a composite of antibacterial agents, disinfectants, bacteriostatic agents, fungicides, antifungal agents, deodorants, anti-odor agents, etc. In the present invention, antibacterial agents, deodorants, and anti-odor agents are preferably used, and deodorants and anti-odor agents are more preferably used. Both deodorants and anti-odor agents are defined as agents that eliminate unpleasant odors such as malodors. For example, as deodorants, those that adsorb unpleasant odors and those that mask unpleasant odors with a pleasant fragrance can be mentioned. In addition, as anti-odor agents, those that suppress the growth of bacteria that cause unpleasant odors can be mentioned. From the viewpoint of compatibility when blended into the resin composition, these functional agents are preferably liquids or water-soluble ones. The present invention more preferably uses deodorants and anti-odor agents that are particularly effective against fecal odors. The resin composition containing such deodorants and anti-odor agents is suitable for use in disposable diaper disposal bags. The functional agent may be a commercially available product and is not particularly limited as long as the effects of the present invention are achieved.

[0066] [Resin Composition]

[0067] The resin composition of the present invention can be thermoplastic. Specific examples of the composition of the thermoplastic resin composition according to the present invention will be described below.

[0068] According to one embodiment of the present invention, the thermoplastic resin composition may include the plasticized starch material, the thermoplastic resin, and the compatibilizer. The composition ratios of the plasticized starch material and the thermoplastic resin are as described above. For example, preferably, they are 20 parts by mass:80 parts by mass to 80 parts by mass:20 parts by mass, more preferably 30 parts by mass:70 parts by mass to 80 parts by mass:20 parts by mass, and even more preferably 50 parts by mass:50 parts by mass to 80 parts by mass:20 parts by mass. The content of the compatibilizer may be, for example, preferably 1 part by mass to 10 parts by mass, more preferably 2 parts by mass to 9 parts by mass, based on 100 parts by mass of the total amount of the plasticized starch material and the thermoplastic resin. In this embodiment, the thermoplastic resin may be, for example, a polyolefin resin, preferably a polyethylene (PE) resin, and more preferably LLPDE. In this embodiment, the compatibilizer may be, for example, a carboxylic anhydride-modified polyolefin, preferably maleic anhydride-modified polyethylene. The thermoplastic resin composition according to this embodiment can be used, for example, to produce a film or a sheet by a molding method such as inflation molding, T-die molding, or calendar molding. In the present invention, a film refers to a thin film-like material, and the thickness of the film may be, for example, less than 200 μm, particularly 10 μm or more and less than 200 μm. Also, in the present invention, a sheet refers to a thin plate-like material, and the thickness of the sheet may be, for example, 200 μm or more, particularly 200 μm or more and 1 mm or less. In this embodiment, the thermoplastic resin may be, for example, a biomass-derived thermoplastic resin, particularly a biomass-derived polyethylene resin.

[0069] According to another embodiment of the present invention, the thermoplastic resin composition may include the plasticized starch material, the thermoplastic resin, the compatibilizer, and the oxidation decomposition accelerator. The composition ratios of the plasticized starch material and the thermoplastic resin are as described above. For example, preferably, they are 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 plasticized starch material 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, more preferably 0.05 part by mass to 3 parts by mass, and even more preferably 0.1 part by mass to 0.5 part by mass, based on 100 parts by mass of the total amount of the plasticized starch material and the thermoplastic resin. In this embodiment, the thermoplastic resin may be, for example, a polyolefin resin, preferably a polyethylene resin, and more preferably LLPDE. In this embodiment, the compatibilizer may be, for example, a carboxylic anhydride-modified polyolefin, preferably maleic anhydride-modified polyethylene. The oxidation decomposition accelerator may be a combination of a carboxylate and a rare earth compound. The thermoplastic resin composition according to this embodiment can be used, for example, to produce a film or a sheet by a molding method such as inflation molding or T-die extrusion. 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. The thickness of the sheet is, for example, 200 μm or more, and particularly may be 200 μm or more and 1.5 mm or less. In this embodiment, the thermoplastic resin may be, for example, a biomass-derived thermoplastic resin, particularly a biomass-derived polyethylene resin. The thermoplastic resin composition according to this embodiment has a high biomass content, and the thermoplastic resin contained in the composition can be biodegradable.

[0070] According to another embodiment of the present invention, the thermoplastic resin composition may include the plasticized starch material, the thermoplastic resin, and the functional agent. The composition ratios of the plasticized starch material and the thermoplastic resin are as described above. For example, preferably, they are 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 functional agent may be, 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 plasticized starch material and the thermoplastic resin. Also, in this embodiment, the compatibilizer may further be included. The content of the compatibilizer may be, 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 plasticized starch material and the thermoplastic resin. Also, in this embodiment, the oxidation decomposition accelerator may further be included. The content of the oxidation decomposition accelerator may be, for example, preferably 0.01 part by mass to 5 parts by mass, more preferably 0.05 part by mass to 3 parts by mass, and even more preferably 0.1 part by mass to 0.5 part by mass, based on 100 parts by mass of the total amount of the plasticized starch material and the thermoplastic resin. In this embodiment, the thermoplastic resin may be, for example, a polyolefin resin, preferably a polyethylene resin, and more preferably LLPDE. In this embodiment, the compatibilizer may be, for example, a carboxylic anhydride-modified polyolefin, preferably maleic anhydride-modified polyethylene. The oxidation decomposition accelerator may be a combination of a carboxylate and a rare earth compound. The thermoplastic resin composition according to this embodiment can be used, for example, to produce a film or a sheet by a molding method such as inflation molding or T-die extrusion. 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. The thickness of the sheet is, for example, 200 μm or more, and particularly may be 200 μm or more and 1.5 mm or less. In this embodiment, the thermoplastic resin may be, for example, a thermoplastic resin derived from biomass, particularly a polyethylene resin derived from biomass. The thermoplastic resin composition according to this embodiment has a high biomass content and the thermoplastic resin contained in the composition can be biodegraded.

[0071] The resin composition of the present invention may be used to produce molded articles other than films and sheets. Examples of such other molded articles include, but are not limited to, containers (e.g., bottle containers), bottle caps, stretch wrap, non-woven fabrics, and monofilaments. For example, the resin composition of the present invention may be used for blow molding, injection molding, profile extrusion molding, and spinning (e.g., melt spinning). By the blow molding, for example, a bottle container can be molded. By the injection molding, for example, a bottle cap or a container can be manufactured. By the profile extrusion molding, for example, stretch wrap can be molded. By the spinning (e.g., melt spinning), for example, a monofilament can be molded.

[0072] The resin composition of the present invention may be produced by the production method described below.

[0073] [Film or sheet]

[0074] The present invention also provides a resin composition molded into the shape of a film or a sheet. The film or sheet may be a single-layer film or sheet composed only of a layer formed from the resin composition according to the present invention, or may be a multi-layer film or sheet in which at least one layer formed from the resin composition according to the present invention and at least one layer formed from another composition (particularly a resin composition) are laminated. The film may have a thickness of less than 200 μm, particularly may have a thickness of 10 μm or more and less than 200 μm. The sheet may have a thickness of 200 μm or more, particularly may have a thickness of 200 μm or more and 1.5 mm or less.

[0075] According to one embodiment of the present invention, the film or sheet has a surface with an average roughness (Ra) measured in accordance with JIS B0031, preferably having a surface with an average roughness of 2 μm or less, more preferably having a surface with an average roughness of 1.8 μm or less, even more preferably having a surface with an average roughness of 1.5 μm or less, and the surface is the surface of a layer formed from the resin composition according to the present invention. The measurement of the average roughness may be measured by a surface roughness meter in accordance with JIS B0031. The resin composition of the present invention can provide a film or sheet having such a smooth surface. The film or sheet provided by the resin composition of the present invention can be suitably used for cards, packaging, containers, separators, covers, partitions, laminates, bags, etc.

[0076] For the production of the sheet or film of the present invention, ordinary petroleum-based plastic molding techniques can be employed. For example, a plasticized starch material and a thermoplastic resin can be mixed in a mixer such as a Henschel mixer, a tumbler-type mixer, a Brabender mixer, a kneader mixer, etc., and the sheet can be molded by a T-die extruder or a calender molding machine, or the film can be molded by an inflation molding machine. Further, the plasticized starch material and the thermoplastic resin as raw materials can be directly kneaded, mixed and molded as they are, or the raw materials can be mixed in a mixer and then strands can be extruded by a single-screw or twin-screw extruder, cut to produce pellets, and the pellets can be used as a masterbatch to mold sheets and films.

[0077] When producing a sheet or film, the molding temperature range employed is preferably in the range of 95 to 200 °C from the viewpoints of suppressing the occurrence of burning and decomposition of the raw materials and sticking in the cylinder and suppressing the plasticized starch material from being discharged in an unmelted state and causing problems with the increase in pressure. Also, when producing and molding master pellets, it is preferably in the range of 95 to 200 °C.

[0078] Also, from the viewpoint of preventing the occurrence of burning and decomposition of the raw materials, the residence time in the cylinder is preferably within 10 minutes at most.

[0079] The sheet extruded by a T-die extruder may be cooled, taken up, and wound up by setting the temperature of the take-up roll to 60°C or lower and forming the sheet into a predetermined thickness. The film extruded by an inflation molding machine may be cooled, taken up, and wound up by setting the temperature of the take-up roll to 90°C or lower and forming the film into a predetermined thickness.

[0080] [Laminate]

[0081] The present invention also provides a laminate in which the surface of the film or sheet is coated with a film. The laminate may be one in which the surface on one side of the film or sheet is coated with a film, or one in which the surfaces on both sides of the film or sheet are coated with a film. By coating the surface of the film or sheet with a film, bleed-out from the coated surface can be suppressed. Examples of the film may include polyolefin resins such as polyethylene (PE) resin and polypropylene (PP) resin, or a combination of two or more of these, and may also include, for example, polylactic acid resin (PLA), polycarbonate resin (PC), polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), or a combination of two or more of 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 and urethane resin.

[0082] In the laminate, the film may have a thickness of less than 200 μm, particularly a thickness of 10 μm or more and less than 200 μm. The sheet may have a thickness of 200 μm or more, particularly a thickness of 200 μm or more and 1.5 mm or less. Also, the membrane may have a thickness of less than 60 μm, particularly a thickness of 10 μm or more and less than 50 μm. The laminate provided by the resin composition of the present invention can be suitably used for cards, covers, packaging, containers, separators, partitions, bags, laminates, etc.

[0083] [Non-woven fabric]

[0084] The present invention also provides a non-woven fabric formed from the resin composition of the present invention. The fiber diameter of the fibers constituting the non-woven fabric is preferably 5 to 30 μm, more preferably 5 to 25 μm, and even more preferably 5 to 20 μm. Also, the average single fiber fineness of the fibers constituting the non-woven fabric is preferably 0.16 dtex or more and 20 dtex or less, more preferably 0.17 dtex or more and 15 dtex or less, and even more preferably 0.17 dtex or more and 10 dtex or less. From the viewpoint of spinning stability, the average single fiber fineness may preferably be 0.17 dtex or more. On the other hand, the finer the fineness, the more adhesion points of the yarns as a non-woven fabric, so the strength is higher and the flexibility is likely to be good. From the viewpoint of the strength of the non-woven fabric, the average single fiber fineness may preferably be 0.2 dtex or less. The above average single fiber fineness can be calculated using the following formula from the fiber cross-sectional area A (m 2 ) and the polymer density ρ (g / m 3 ). · Single fiber fineness (dtex) = A (m 2 ) × ρ (g / m 3 ) × 10000 (m).

[0085] In the present invention, the non-woven fabric preferably has a basis weight of 10 to 200 g / m 2 , more preferably 10 to 190 g / m 2 , and even more preferably 20 to 180 g / m 2It is possible. By setting the basis weight within the above range, sufficient strength can be obtained, particularly when used as a nonwoven fabric for shopping bags.

[0086] In the present invention, the apparent density of the nonwoven fabric is preferably 0.3 g / cm 3 or less, more preferably 0.2 g / cm 3 or less, and even more preferably 0.15 g / cm 3 or less. By setting the apparent density within the above range, sufficient bulkiness can be obtained, particularly when used as a nonwoven fabric for wiping. The apparent density can be calculated by dividing the basis weight by the thickness.

[0087] The nonwoven fabric of the present invention may be produced by the spunbond method, the meltblown method, or the like. For example, the spunbond method involves heating and melting the resin composition of the present invention, spinning it from a spinneret, then pulling and stretching the cooled and solidified filament group with an ejector, collecting and depositing it on a moving net to form a web, and then heat-bonding it by heat-pressing with an embossing roller.

[0088] As the shapes of the spinneret and the ejector, various shapes such as round and rectangular can be adopted. Among them, a combination of a rectangular die and a rectangular ejector is preferably used from the viewpoint of relatively less use of compressed air and less likelihood of fusion and friction between filaments. A spinneret having a round discharge shape is preferably used.

[0089] The spinning temperature when melting and spinning is preferably 200 to 300 °C, more preferably 210 to 280 °C, and even more preferably 220 to 260 °C. By setting the spinning temperature within the above range, a stable molten state can be obtained, and excellent spinning stability can be achieved. The resin composition (raw material) is melted, metered by an extruder, supplied to the spinneret, and spun out from the die discharge holes.

[0090] As a method for cooling the fiber group of the spun filaments, a normal method is adopted. For example, it may be cooled by blowing cooling air onto the filaments spun from the spinneret.

[0091] The cooled and solidified fiber group is drawn and stretched by the compressed air ejected from the ejector. Then, it is collected on a moving net to form a non-woven web, and the obtained non-woven web can be integrated by thermal adhesion to obtain a non-woven fabric.

[0092] As the method of thermal adhesion, for example, thermal embossing rolls with engraving (concave and convex parts) applied to the surfaces of a pair of upper and lower rolls respectively, thermal embossing rolls composed of a combination of a roll with a flat (smooth) surface on one side and a roll with engraving (concave and convex parts) on the other side, thermal calender rolls composed of a combination of a pair of upper and lower flat (smooth) rolls, etc., thermal pressure bonding by various rolls, or fusion bonding by ultrasonic waves can be applied.

[0093] Among them, from the viewpoints of strength and wear resistance, thermal adhesion using an embossing roll can be preferably adopted. Also, from the viewpoint that it is difficult for pressure to be applied overall, it is better to use a roll with engraving (concave and convex parts) on either the upper or lower side.

[0094] As the shape of the engraving applied to the thermal embossing roll, shapes such as circular, elliptical, square, rectangular, parallelogram, rhombus, regular hexagon, and regular octagon can be used.

[0095] The surface temperature of the thermal embossing roll can preferably be -50 to -5 °C with respect to the melting point of the resin composition. By setting the surface temperature of the thermal embossing roll to be preferably -50 °C or higher, more preferably -40 °C or higher, and even more preferably -30 °C or higher with respect to the melting point of the resin composition, sufficient thermal adhesion can be achieved to provide strength and it is easy to suppress the generation of fluff.

[0096] Further, by setting the surface temperature of the thermal embossing roll to -5°C or lower with respect to the melting point of the resin composition, it is possible to easily prevent the separation of the resins due to the melting of the fibers.

[0097] The linear pressure of the thermal embossing roll during thermal adhesion can preferably be 5 to 50 kgf / cm. By setting the linear pressure to preferably 5 kgf / cm or more, more preferably 10 kgf / cm or more, and even more preferably 15 kgf / cm or more, sufficient thermal adhesion can be achieved. On the other hand, by setting the linear pressure to preferably 50 kgf / cm or less, more preferably 40 kgf / cm or less, and even more preferably 30 kgf / cm or less, it is possible to maintain bulkiness because the stress on the roll is not excessive. The non-woven fabric provided by the resin composition of the present invention can be suitably used for covers, bags, various filters, wet sheets, masks, separators, containers, and packaging.

[0098] 2. Plasticized starch

[0099] The plasticized starch of the present invention has a plasticized starch material containing starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water. The plasticized starch of the present invention preferably has a hardness of 20 or more, more preferably 23 or more, and even more preferably 25 or more on the durometer type D. All of the explanations regarding the plasticized starch material in the above "1. Resin composition" (for example, composition and details of each component, etc.) also apply to the plasticized starch material used in the plasticized starch of the present invention. Therefore, the explanation of the plasticized starch material of the present invention is omitted. The plasticized starch material exhibits the effects as described in the above "1. Resin composition". For example, the plasticized starch material can reduce the particle size of the starch contained in the resin composition, and further suppress the bleeding out of various additives from the surface during high temperature and high humidity.

[0100] The plasticized starch of the present invention preferably has no foamed portion. Foaming may occur due to the evaporation of volatile components in the production of the plasticized starch material. Further, the plasticized starch of the present invention may be used to produce a plasticized starch-containing resin composition containing starch granules having a particle diameter of 2 μm or less. The plasticized starch of the present invention may contain the functional agent in addition to the compatibilizer, the oxidation decomposition accelerator, the colorant, and the antioxidant. Examples of such functional agents include antibacterial agents, disinfectants, bacteriostatic agents, fungicides, mold inhibitors, deodorants, and odor preventives. The functional agent may be at least one selected from a single substance or a composite of antibacterial agents, disinfectants, bacteriostatic agents, fungicides, mold inhibitors, deodorants, odor preventives, etc. In the present invention, antibacterial agents, deodorants, and odor preventives are preferably used, and deodorants and odor preventives are more preferably used.

[0101] 3. Method for producing resin composition

[0102] [One embodiment of the method for producing a resin composition]

[0103] One embodiment of the method for producing a resin composition according to the present invention includes 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 plasticizing the starch by heating the mixture obtained in the first mixing step to prepare plasticized starch. And a second mixing step of mixing the plasticized starch and the thermoplastic resin to obtain a resin composition containing starch granules having a particle diameter of 2 μm or less. According to one embodiment of the method for producing a resin composition of the present invention, the resin composition of the present invention described in the above "1. Resin composition" can be produced.

[0104] The manufacturing method will be described for each step below.

[0105] (1) First mixing step

[0106] In the first mixing step, starch, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, and water are mixed. The starch and the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature are as described in the above "1. Resin composition", and the description thereof also applies to this production method.

[0107] In the first mixing step, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature can be mixed with the starch in an amount preferably of 5 to 40 parts by mass, more preferably of 10 to 40 parts by mass, even more preferably of 20 to 40 parts by mass, per 100 parts by mass of the starch. The polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature may contain at least one polyhydric alcohol. Examples of such polyhydric alcohols include one or a combination of two or more selected from ethylene glycol, propylene glycol, and glycerin, preferably ethylene glycol and propylene glycol.

[0108] The polyhydric alcohol may more preferably contain glycerin and / or ethylene glycol. In the first mixing step, the ratio of the mass of glycerin to the mass of ethylene glycol is, for example, preferably 1:8 to 0.5:1, more preferably 1:4 to 1:1, still more preferably 1:3 to 1:1, and glycerin and ethylene glycol can be used. Further, the polyhydric alcohol may more preferably contain glycerin and / or propylene glycol. In the first mixing step, the ratio of the mass of glycerin to the mass of propylene glycol is preferably 1:8 to 0.5:1, more preferably 1:4 to 1:1, still more preferably 1:3 to 1:1, and glycerin and propylene glycol can be used. Incidentally, the polyhydric alcohol may be only glycerin. Further, it may contain no glycerin and may be only ethylene glycol or only propylene glycol as the polyhydric alcohol. From the viewpoint of suppressing the occurrence of bleed, when only glycerin is used, glycerin is preferably mixed with the starch in a blending amount of 40 parts by mass or less, more preferably 38 parts by mass or less, still more preferably 35 parts by mass or less, based on 100 parts by mass of the starch.

[0109] When the amount of glycerin as the polyhydric alcohol is 25 parts by weight or less, from the viewpoint of making the starch granules in the resin composition small, it may preferably contain an organic acid. Such organic acids may be, for example, succinic acid, malic acid, maleic acid, tartaric acid, adipic acid, gluconic acid, lactic acid, etc. or their anhydrides. As the organic acid, from the viewpoints of preventing discoloration and the balance between price and effect, succinic acid, malic acid, tartaric acid, maleic acid, etc. are preferable, and succinic acid and tartaric acid are more preferable. The organic acid is preferably mixed with the starch in a blending amount of 0.1 to 5 parts by mass, more preferably 0.3 parts by mass to 4 parts by mass, still more preferably 0.5 parts by mass to 3 parts by mass, based on 100 parts by mass of the starch.

[0110] The water used in the first mixing step is preferably mixed with the starch in an amount of 10 to 40 parts by mass, more preferably 15 to 30 parts by mass, and even more preferably 20 to 30 parts by mass, based on 100 parts by mass of the starch.

[0111] In the first mixing step, the functional agent may be further added. The amount of the functional agent added is preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, and even more preferably 2 to 9 parts by mass, based on 100 parts by mass of the starch, and is mixed with the starch.

[0112] Examples of the starch used in the first mixing step include underground starch and above-ground starch, and for example, corn starch or tapioca starch may be used. In the present invention, underground starch is preferably used. By producing the resin composition of the present invention using underground starch, the odor of the resin composition can be further reduced. The starch used in the first mixing step may be a modified starch (i.e., a denatured starch).

[0113] The starch used in the first mixing step preferably contains equilibrium moisture. The amount of equilibrium moisture is, for example, preferably 10% to 15% by mass, more preferably 10% to 14% by mass, even more preferably 10% to 13% by mass, and even more preferably 11% to 13% by mass, based on the starch mass. It is preferable to use starch or modified starch containing equilibrium moisture within the above numerical range to produce a plasticized starch material according to the present invention. When starch that does not contain equilibrium moisture is used, the starch may not be plasticized.

[0114] The first mixing step may be performed, for example, using a stirrer. As the stirrer, a commercially available device may be used. The first pre-mixing step is preferably performed at room temperature. By performing the first mixing step at room temperature and then performing the following plasticized starch preparation step, it is possible to suppress the generation of coloring and / or odor due to the heating of the starch.

[0115] The starch may account for, for example, preferably 40% to 85% by mass, more preferably 45% to 80% by mass, and still more preferably 50% to 75% by mass of the total amount of raw materials used for producing the plasticized starch.

[0116] (2) Plasticized starch preparation step

[0117] The plasticized starch preparation step includes heating the mixture obtained in the first mixing step in an extruder. By this heating, the starch is plasticized to obtain plasticized starch. The heating can be preferably performed at a temperature of 100°C to 150°C, more preferably at a temperature of 100°C to 140°C, and still more preferably at a temperature of 100°C to 130°C. The extruder may be, for example, a twin-screw extruder or a single-screw extruder, and a commercially available one may be used. The plasticized starch extruded from the extruder may have, for example, a cylindrical (strand) or pellet shape.

[0118] The description regarding the plasticized starch material described in the above "1. Resin composition" also applies to the plasticized starch in this manufacturing method. For example, the hardness of the masterbatch is 20 or more on the durometer type D.

[0119] (3) Second mixing step

[0120] In the second mixing step, the plasticized starch prepared in the plasticized starch preparation step and the thermoplastic resin are mixed. By this mixing, the resin composition according to the present invention is produced. This mixing may be carried out, for example, using an extruder, preferably a twin-screw extruder. In this mixing step, in addition to the plasticized starch and the thermoplastic resin, a compatibilizer may be mixed. Since the compatibilizer is as described in the above "1. Resin Composition", the description thereof is omitted.

[0121] In the second mixing step, the components to be mixed (for example, the plasticized starch and the thermoplastic resin, and optionally the compatibilizer) are heated. This heating is carried out so that the thermoplastic resin melts, preferably at a temperature of 100°C to 200°C, more preferably at a temperature of 100°C to 190°C, and even more preferably at a temperature of 100°C to 180°C. The components to be mixed may be heated, for example, up to the temperature at which the thermoplastic resin melts. This temperature may be appropriately selected by those skilled in the art according to the type of thermoplastic resin.

[0122] The manufacturing method may further include a molding step of molding the resin composition obtained in the mixing step. By this molding step, a molded article having a desired shape is produced. This molding may be, for example, inflation molding or T-die molding. By such a molding method, a resin composition molded into the shape of a film or a sheet can be produced. The molding temperature may be appropriately selected by those skilled in the art according to the type of thermoplastic resin. For example, when the thermoplastic resin is polyethylene, the temperature may be 160°C to 200°C. For example, when the thermoplastic resin is polypropylene, the temperature may also be 160°C to 200°C.

[0123] The manufacturing method may further include a stretching step of stretching the resin composition molded into the shape of a film or a sheet in the molding step.

[0124] [Other Embodiments of the Manufacturing Method of the Resin Composition]

[0125] Another embodiment of the method for producing a resin composition according to the present invention includes a mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, water, and a thermoplastic resin, and a heating step of heating the mixture obtained in the mixing step to plasticize the starch, wherein the particle diameter of the starch granules contained in the obtained resin composition is 2 μm or less. According to another embodiment of the production method of the present invention, the resin composition of the present invention described in the above "1. Resin composition" can be produced.

[0126] In another embodiment, unlike the above production method, without previously preparing plasticized starch, each raw material component (plasticized starch material, thermoplastic resin, etc.) is directly mixed.

[0127] The production method will be described for each step below.

[0128] (1) Mixing step

[0129] In the mixing step, starch, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, water, and a thermoplastic resin are mixed. The starch, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, and the thermoplastic resin are as described in the above "1. Resin composition", and the description also applies to this production method.

[0130] In the mixing step, the polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature is preferably mixed with the starch in an amount of 5 to 40 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 20 to 40 parts by mass, based on 100 parts by mass of the starch.

[0131] The water used in the mixing step is preferably mixed with the starch in an amount of 10 to 40 parts by mass, more preferably 15 to 30 parts by mass, and even more preferably 20 to 30 parts by mass, based on 100 parts by mass of the starch.

[0132] In the mixing step, the functional agent may be further mixed. The functional agent is preferably mixed with the starch in an amount of 1 part by mass to 15 parts by mass, more preferably 2 parts by mass to 10 parts by mass, and even more preferably 2 parts by mass to 9 parts by mass, based on 100 parts by mass of the starch.

[0133] The thermoplastic resin used in the mixing step is preferably mixed with the starch in an amount of 10 parts by mass to 900 parts by mass, more preferably 10 parts by mass to 800 parts by mass, and even more preferably 15 parts by mass to 800 parts by mass, based on 100 parts by mass of the starch.

[0134] (2) Heating step

[0135] In the heating step, the mixture obtained in the mixing step is heated. The heating can be performed so that the thermoplastic resin melts. The components to be mixed may be heated, for example, to a temperature at which the thermoplastic resin melts. The temperature may be appropriately selected by those skilled in the art according to the type of the thermoplastic resin. For example, when the thermoplastic resin is polyethylene, the temperature can be 100°C to 170°C. For example, when the thermoplastic resin is polypropylene, the temperature can be 150°C to 200°C. The particle diameter of the starch granules contained in the resin composition produced by the mixing step and the heating step is 2 μm or less.

[0136] 4. Method for producing plasticized starch

[0137] One embodiment of the method for producing plasticized starch according to the present invention includes a 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 plasticizing step of plasticizing the starch by heating the mixture obtained in the mixing step.

[0138] (1) Mixing step In the mixing step, starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water are mixed. The starch and the polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature are as described in the above "1. Resin Composition", and the description also applies to this manufacturing method.

[0139] In the mixing step, the polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature is preferably mixed with the starch in an amount of 5 to 40 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 20 to 40 parts by mass, based on 100 parts by mass of the starch.

[0140] The water used in the mixing step is preferably mixed with the starch in an amount of 10 to 40 parts by mass, more preferably 15 to 30 parts by mass, and even more preferably 20 to 30 parts by mass, based on 100 parts by mass of the starch.

[0141] The functional agent may be mixed in the mixing step. The functional agent is preferably mixed with the starch in an amount of 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, and even more preferably 2 to 9 parts by mass, based on 100 parts by mass of the starch.

[0142] (2) Plasticizing step

[0143] In the plasticizing process, the mixture obtained in the mixing process is heated in an extruder. This heating can be carried out so that the starch is plasticized. The components to be mixed may be heated, for example, to the temperature at which the starch is plasticized. This temperature may be appropriately selected by those skilled in the art according to the type of starch. For example, this temperature can preferably be in the range of 100°C to 150°C, more preferably in the range of 100°C to 140°C, and even more preferably in the range of 100°C to 130°C. The extruder may be, for example, a twin-screw extruder or a single-screw extruder, and commercially available ones may be used. The plasticized starch extruded from the extruder may have, for example, a cylindrical (strand) or pellet shape.

[0144] 5. Use of the present invention The film or sheet formed by inflation molding, T-die molding, calendar molding, etc. of the resin composition of the present invention is used for vacuum molding applications such as containers, various release films, release sheets, greenhouse films, tunnel films, multilayer films, vegetation films, civil engineering sheets, etc. The bag formed by inflation molding of the resin composition of the present invention is used for shopping bags, garbage bags, compost bags, plastic bags, etc. The blow molded body formed by blow molding, etc. of the resin composition of the present invention is used for blow bottles, beverage bottles, bottle containers, etc. The injection molded body formed by injection molding of the resin composition of the present invention is used for bottle caps, various food containers, etc. The non-woven fabric spun by the spunbond method, meltblown method, etc. of the resin composition of the present invention is used for covers, bags, various filters, wet wipes, masks, separators, containers, packaging. Further, when the resin composition of the present invention contains a biodegradable resin for reducing environmental load, the molded body formed by the resin composition is used for the above-mentioned applications. In addition, the resin composition of the present invention containing cellulose nanofibers to improve strength is used for the above-mentioned applications. The resin composition of the present invention containing functional agents such as deodorants, anti-odor agents, antibacterial agents, etc. is used for the above-mentioned applications, and particularly preferably for various sanitary products such as garbage bags, used diaper storage bags, etc. Furthermore, the resin composition of the present invention is used for applications such as laminates with suppressed bleeding.

Examples

[0145] Hereinafter, the present invention will be described in more detail based on examples. It should be noted that the examples described below show an example of a typical embodiment 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.

[0146] (1) Presence or absence of bubbles in plasticized starch The presence or absence of bubbles in plasticized starch was visually confirmed and evaluated according to the following criteria. A: Bubbles did not occur throughout the plasticized starch. B: Bubbles were generated in part of the plasticized starch. C: Bubbles were generated throughout the plasticized starch.

[0147] (2) Physical properties of the plasticized starch The physical properties of the plasticized starch were evaluated according to the following criteria. A: It had a hardness of 20 or more on the durometer type D. C: It had a hardness of less than 20 on the durometer type D, or bubbles were generated (expanded) throughout the plasticized starch and the hardness could not be measured.

[0148] (3) Particle diameter of starch particles The surface of the film sample or nonwoven fabric sample was observed (secondary electron image) at an acceleration voltage of 5.0 kV using an SEM (scanning electron microscope) JSM-IT100 (JEOL Ltd.). For each sample, four regions of 200 μm × 250 μm were photographed at a magnification of 500 times. The particle diameters of the starch particles included in each photographed image were measured using the in-field scale.

[0149] (4) Presence or absence of bleed Using the film sample, a cut sample of 10 cm in length and 10 cm in width was left standing in a thermo-hygrostat maintained at 40 °C × 80% RH for 12 hours. After 12 hours, the presence or absence of bleed was evaluated by touch. Specifically, five panelists evaluated the presence or absence of bleed on the surface of the film sample by touch based on the following criteria. A: There was no bleed and no stickiness. B: Slight bleed occurred and there was some stickiness. C: Bleed occurred and it was sticky.

[0150] (5) Tensile properties Using injection molded products, the tensile properties (maximum point stress, elongation at break, elastic modulus) were measured according to JIS K 7161.

[0151] (6) Izod impact strength The Izod impact strength was measured in accordance with JIS K 7110 using injection molded products.

[0152] (7) Production efficiency The production efficiency was evaluated based on the cooling time. The shorter the cooling time, the higher the production efficiency.

[0153] Test Example 1: Production and Molding of Resin Composition (Examples of Films or Sheets)

[0154] (Example 1)

[0155] As shown in Table 1 below, 100 parts by mass of phosphorylated tapioca starch (T-1, Matsutani Chemical Industry Co., Ltd.), 12 parts by mass of glycerin, 22 parts by mass of ethylene glycol, and 27 parts by mass of water were prepared as a plasticized starch material. These four components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, the ethylene glycol, and the water were premixed before being charged into the mixer.

[0156] The mixture obtained by the mixing was a powdery mixture.

[0157] The mixture obtained by the mixing was fed into a twin-screw extruder (PCM30, Ikegai Corporation), and the mixture was subjected to a kneading process.

[0158] 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 (masterbatch) was obtained.

[0159] Regarding the plasticized starch, the presence or absence of bubbles and the durometer hardness were evaluated according to the above criteria.

[0160] The evaluation results are as shown in Table 1 below, and no bubbles were formed throughout the plasticized starch. Also, the plasticized starch had a hardness of 27 on the durometer type D.

[0161] 35 parts by mass of the plasticized starch, 70 parts by mass of polypropylene (PM900C, manufactured by San Allomer Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polypropylene, DuPont Co., Ltd.) 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 resin composition (hereinafter, also referred to as "the resin composition of Example 1") was obtained.

[0162] The 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 the inflation molding, a film with a thickness of 40 μm was obtained.

[0163] The moldability in inflation molding, the particle diameter of starch particles on the film surface, and the presence or absence of bleed were evaluated according to the above methods and criteria. The evaluation results are as shown in Table 1 below, and an electron micrograph of the obtained film is shown in Fig. 1(a). As shown in Fig. 1(a), the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, a slight bleed occurred and it was slightly sticky.

[0164]

Table 1

[0165] (Example 2)

[0166] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 4 parts by mass of glycerin, 30 parts by mass of ethylene glycol, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. The glycerin, the ethylene glycol, and the water were premixed before being charged into the mixer.

[0167] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 2") was obtained in the same manner as in Example 1.

[0168] Using the resin composition of Example 2, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0169] Also in Example 2, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. Regarding the plasticized starch, the same evaluation results as in Example 1 were obtained as shown in Table 1.

[0170] More specifically, the plasticized starch produced in Example 2 had no generation of bubbles throughout and had a hardness of 27 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and no stickiness.

[0171] (Example 3)

[0172] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. The glycerin, the ethylene glycol, and the water were premixed before being charged into the mixer.

[0173] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 3") was obtained in the same manner as in Example 1.

[0174] Using the resin composition of Example 3, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0175] Also in Example 3, the same evaluation as in Example 1 was carried out. The evaluation results are shown in Table 1 above. Regarding the plasticized starch, the same evaluation results as in Example 1 were obtained as shown in Table 1 above.

[0176] More specifically, the plasticized starch produced in Example 3 had no generation of bubbles throughout and had a hardness of 25 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and it was non-sticky.

[0177] (Example 4)

[0178] As shown in Table 1 above, in the mixer, as a plasticized starch material, 100 parts by mass of phosphate-crosslinked tapioca starch, 12 parts by mass of glycerin, 22 parts by mass of ethylene glycol, and 27 parts by mass of water in which CNF (product name broadleaf tree, Daio Paper Corporation) was suspended at 2% were prepared, and these four components were mixed in the mixer in the same manner as in Example 1 to obtain a mixture.

[0179] Using the mixture, kneading treatment was carried out in the same manner as in Example 1 to obtain a plasticized starch containing CNF. Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 4") was obtained in the same manner as in Example 1.

[0180] Using the resin composition of Example 4, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0181] Also in Example 4, the same evaluation as in Example 1 was carried out. Regarding the plasticized starch, the same evaluation results as in Example 1 were obtained as shown in Table 1 above.

[0182] More specifically, the plasticized starch produced in Example 4 had no generation of air bubbles throughout and had a hardness of 25 on the durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, slight bleeding occurred and it was slightly sticky.

[0183] (Example 5)

[0184] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 7 parts by mass of glycerin, 27 parts by mass of propylene glycol, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. Note that the glycerin, the propylene glycol, and the water were premixed before being charged into the mixer.

[0185] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 5") was obtained in the same manner as in Example 1.

[0186] Using the resin composition of Example 5, inflation molding was performed in the same manner as in Example 1 to obtain a film.

[0187] Also in Example 5, the same evaluation as in Example 1 was performed. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0188] More specifically, the plasticized starch produced in Example 5 had no generation of air bubbles throughout and had a hardness of 27 on the durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and it was not sticky.

[0189] (Example 6)

[0190] As shown in Table 1 above, in the mixer, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 12 parts by mass of glycerin, 22 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were mixed as the plasticized starch material, plasticized starch was obtained in the same manner as in Example 1. Note that the glycerin, ethylene glycol, water, and succinic acid were premixed before being charged into the mixer.

[0191] Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Example 6") was obtained in the same manner as in Example 1.

[0192] Using the resin composition of Example 6, inflation molding was performed in the same manner as in Example 1 to obtain a film.

[0193] In Example 6 as well, the same evaluation as in Example 1 was performed. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0194] More specifically, the plasticized starch produced in Example 6 had no generation of bubbles throughout and had a hardness of 25 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and no stickiness.

[0195] (Example 7)

[0196] As shown in Table 1 above, in the mixer, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 34 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were mixed as the plasticized starch material, plasticized starch was obtained in the same manner as in Example 1. Note that the ethylene glycol, water, and succinic acid were premixed before being charged into the mixer.

[0197] Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Example 7") was obtained in the same manner as in Example 1.

[0198] Using the resin composition of Example 7, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0199] Also in Example 7, the same evaluation as in Example 1 was conducted. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0200] More specifically, the plasticized starch produced in Example 7 had no generation of bubbles throughout and had a hardness of 26 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and it was non-sticky.

[0201] (Example 8)

[0202] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that in the mixer, 100 parts by mass of phosphoric acid-crosslinked tapioca starch, 34 parts by mass of glycerin, and 27 parts by mass of water were mixed as the plasticized starch material. The glycerin and the water were premixed before being charged into the mixer.

[0203] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 8") was obtained in the same manner as in Example 1.

[0204] Using the resin composition of Example 8, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0205] Also in Example 8, the same evaluation as in Example 1 was conducted. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0206] More specifically, the plasticized starch produced in Example 8 had no generation of air bubbles throughout and had a hardness of 24 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, bleeding occurred on the film surface and it was sticky.

[0207] (Example 9)

[0208] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that in the mixer, 100 parts by mass of corn starch (product name: Showa Corn Starch, Showa Sangyo Co., Ltd.), 34 parts by mass of glycerin, and 27 parts by mass of water were mixed as the plasticized starch material. The glycerin and the water were premixed before being charged into the mixer.

[0209] Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Example 9") was obtained in the same manner as in Example 1.

[0210] Using the resin composition of Example 9, inflation molding was performed in the same manner as in Example 1 to obtain a film.

[0211] Also in Example 9, the same evaluation as in Example 1 was conducted. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0212] More specifically, the plasticized starch produced in Example 9 had no generation of air bubbles throughout and had a hardness of 25 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, bleeding occurred on the film surface and it was sticky.

[0213] (Example 10)

[0214] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 12 parts by mass of glycerin, 22 parts by mass of ethylene glycol, and 27 parts by mass of water were mixed in the mixer.

[0215] 70 parts by mass of the plasticized starch, 40 parts by mass of polypropylene (FL6632G, Sumitomo Chemical Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polypropylene, DuPont Co., Ltd.) 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 resin composition (hereinafter, also referred to as "the resin composition of Example 10") was obtained.

[0216] The resin composition of Example 10 was supplied to a sheet extruder (LAB TECH Engineering Co., Ltd.) to perform sheet extrusion molding. The sheet extrusion molding was performed at 180 to 200 °C. By the sheet extrusion molding, a sheet having a thickness of 0.5 mm (hereinafter, also referred to as "the sheet of Example 10") was obtained.

[0217] In the sheet of Example 10, the same evaluation as in Example 1 was also performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the same evaluation results as in Example 4 were obtained.

[0218] (Comparative Example 1)

[0219] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that 100 parts by mass of corn starch, 25 parts by mass of glycerin, and 31 parts by mass of water were mixed as a plasticized starch material in the mixer. Incidentally, the glycerin and water were premixed before being charged into the mixer.

[0220] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Comparative Example 1") was obtained in the same manner as in Example 1.

[0221] Using the resin composition of Comparative Example 1, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0222] Also in Comparative Example 1, the same evaluation as in Example 1 was performed. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0223] More specifically, the plasticized starch produced in Comparative Example 1 had no generation of bubbles throughout and had a hardness of 26 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 50 μm. Also, bleeding occurred on the film surface and it was sticky.

[0224] (Comparative Example 2)

[0225] As shown in Table 1 above, plasticized starch was obtained in the same manner as in Example 1, except that 100 parts by mass of the phosphate cross-linked tapioca starch, 34 parts by mass of ethylene glycol, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. The ethylene glycol and water were premixed before being charged into the mixer.

[0226] Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Comparative Example 2") was obtained in the same manner as in Example 1.

[0227] Using the resin composition of Comparative Example 2, inflation molding was carried out in the same manner as in Example 1 to obtain a film.

[0228] Also in Comparative Example 2, the same evaluation as in Example 1 was performed. Regarding the plasticized starch, as shown in Table 1 above, the same evaluation results as in Example 1 were obtained.

[0229] More specifically, the plasticized starch produced in Comparative Example 2 had no generation of bubbles throughout and had a hardness of 27 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 100 μm. Also, on the film surface, there was no bleeding and it was not sticky.

[0230] An electron micrograph of the obtained film is shown in Fig. 1(b). As shown in Fig. 1(b), in the film containing starch that was not sufficiently plasticized, a large number of starch particles with a particle diameter of about 100 μm were confirmed on the surface.

[0231] (Summary of evaluation results)

[0232] In Examples 1 to 10, the particle diameter of the starch was as small as 2 μm. On the other hand, the particle diameters of the starch in Comparative Examples 1 and 2 were as large as 50 μm and 100 μm, respectively.

[0233] Test Example 2: Production and molding of a resin composition containing CNF

[0234] (Example 11)

[0235] As a plasticized starch material, 100 parts by mass of phosphate-crosslinked tapioca starch, 12 parts by mass of glycerin, 22 parts by mass of ethylene glycol, and 27 parts by mass of water in which CNF (product name broad-leaved tree, Daio Paper Corporation) was suspended at 2% were prepared, and these four components were mixed in a mixer in the same manner as in Example 1 to obtain a mixture. Using the said mixture, kneading treatment was performed in the same manner as in Example 1 to obtain plasticized starch containing CNF. The said plasticized starch and polypropylene were kneaded by a twin-screw extruder (PCM30, Ikegai Corporation) to obtain a resin composition (hereinafter, also referred to as "the resin composition of Example 11").

[0236] The resin composition of Example 11 was supplied to an injection molding machine (SH-125, Sumitomo Heavy Industries, Ltd.) and injection molding was performed. The said injection molding was performed at 180°C. By the said injection molding, an injection molded product (conforming to JIS K 7161) (hereinafter, also referred to as "the injection molded product of Example 11") was obtained.

[0237] (Example 12)

[0238] Using the resin composition of Example 1, an injection molded article (hereinafter, also referred to as "the injection molded article of Example 12") was obtained by the above molding method.

[0239] Using the injection molded article of Example 11 and the injection molded article of Example 12, the tensile physical properties (maximum point stress, elongation at break, elastic modulus) were measured according to JIS K 7161. Also, using these, the Izod impact strength was measured according to JIS K 7110. The measurement results are shown in Table 2 below.

[0240] As shown in Table 2, the injection molded article of Example 11 had a higher tensile strength and a higher tensile elongation than the injection molded article of Example 12. Therefore, it can be seen that by including CNF, the tensile strength and the tensile elongation can be improved.

[0241] Also, the injection molded article of Example 11 had a shorter cooling time during production than the injection molded article of Example 12 and was excellent in terms of production efficiency. Furthermore, although CNF is difficult to be dispersed in a thermoplastic resin such as polypropylene, CNF was well dispersed in the resin composition of Example 11. Therefore, it can also be seen that by mixing plasticized starch containing CNF with a thermoplastic resin, CNF can be well dispersed in the thermoplastic resin.

[0242]

Table 2

[0243] Test Example 3: Influence of Organic Acid Addition

[0244] (Example 13)

[0245] As shown in Table 3 below, as a plasticized starch material, 100 parts by mass of phosphoric acid-crosslinked tapioca starch (product name T-1, Matsutani Chemical Industry Co., Ltd.), 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were prepared. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, the ethylene glycol, the water, and the succinic acid were premixed before being charged into the mixer. Note that Table 3 below shows the parts by mass of other components of the plasticized starch material when the amount of the phosphoric acid-crosslinked tapioca starch is 100 parts by mass.

[0246] The mixture obtained by the mixing was a powdery mixture. The plasticized starch was obtained from the powdery mixture in the same manner as in Example 1.

[0247] 40 parts by mass of the plasticized starch, 70 parts by mass of polypropylene (PM900C, San Allomer Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, DuPont Co., Ltd.) 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 resin composition (hereinafter, also referred to as "the resin composition of Example 13") was obtained.

[0248] The resin composition of Example 13 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.

[0249] Also in Example 13, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3 below. As shown in Table 3, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and no stickiness.

[0250] (Example 14)

[0251] Plasticized starch was obtained in the same manner as in Example 13, except that 1 part by mass of maleic acid was blended instead of succinic acid as the organic acid. Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Example 14") was obtained in the same manner as in Example 13.

[0252] Using the resin composition of Example 14, inflation molding was carried out in the same manner as in Example 13 to obtain a film.

[0253] In Example 14 as well, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3 below. As shown in Table 3, the same evaluation results as in Example 13 were obtained.

[0254] (Example 15)

[0255] Plasticized starch was obtained in the same manner as in Example 13, except that 100 parts by mass of phosphoric acid cross-linked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of glycerin, 27 parts by mass of water, and 3 parts by mass of maleic acid were blended. Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Example 15") was obtained in the same manner as in Example 13.

[0256] Using the resin composition of Example 15, inflation molding was carried out in the same manner as in Example 13 to obtain a film.

[0257] In Example 15 as well, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3 below. As shown in Table 3, the particle diameter of the starch particles on the film surface was 2 μm. However, bleeding occurred on the film surface, and it was sticky.

[0258] (Example 16)

[0259] As shown in Table 3 below, plasticized starch was obtained in the same manner as in Example 13, except that 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of glycerin, and 27 parts by mass of water were blended. Using the obtained plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 16") was obtained in the same manner as in Example 13.

[0260] Using the resin composition of Example 16, inflation molding was carried out in the same manner as in Example 13 to obtain a film.

[0261] In Example 16 as well, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3 below. As shown in Table 3, the particle diameter of the starch particles on the film surface was 2 μm. However, bleeding occurred on the film surface, and it was sticky.

[0262] (Comparative Example 3)

[0263] As shown in Table 3 below, plasticized starch was obtained in the same manner as in Example 11, except that 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, and 27 parts by mass of water were blended and no organic acid was blended. Using the obtained plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Comparative Example 3") was obtained in the same manner as in Example 12.

[0264] Using the resin composition of Comparative Example 3, inflation molding was carried out in the same manner as in Example 13 to obtain a film.

[0265] In Comparative Example 3 as well, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3 below. As shown in Table 3, the particle diameter of the starch particles on the film surface was 100 μm.

[0266]

Table 3

[0267] Test Example 3: Manufacture and Evaluation of Laminated Body

[0268] (Example 17)

[0269] As shown in Table 4 below, 100 parts by mass of phosphoric acid-crosslinked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of glycerin, and 27 parts by mass of water were blended, and plasticized starch was obtained in the same manner as in Example 1.

[0270] 60 parts by mass of the plasticized starch, 40 parts by mass of polypropylene (PM900C, San Allomer Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polypropylene, DuPont Co., Ltd.) 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 resin composition (hereinafter, also referred to as "the resin composition of Example 17") was obtained.

[0271] Using the resin composition of Example 17, sheet extrusion molding was performed in the same manner as in Example 10 to obtain a sheet (hereinafter, also referred to as "the sheet of Example 17").

[0272] Both surfaces of the sheet of Example 17 were coated with a polyethylene film having a thickness of 20 μm and subjected to a vacuum laminating process using a vacuum laminator (LM-50X50-S, N.C.P. Co., Ltd.). The laminating process was performed at 120°C. By the sheet extrusion molding, a laminated body having a thickness of 0.5 mm (also referred to as "the laminated body of Example 17") was obtained.

[0273] In the laminated body of Example 17 as well, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 4 below. As shown in Table 4, the starch grains observed by SEM of the sheet obtained from the resin composition of Example 17 were 2 μm, and there was no bleeding and stickiness.

[0274] (Comparative Example 4)

[0275] As shown in Table 4 below, plasticized starch was obtained in the same manner as in Example 17, except that 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 12 parts by mass of glycerin, 22 parts by mass of ethylene glycol, and 27 parts by mass of water were blended.

[0276] Using 70 parts by mass of the plasticized starch, 40 parts by mass of polypropylene (PM900C, San Allomer Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polypropylene, DuPont Co., Ltd.), a resin composition (hereinafter also referred to as "the resin composition of Comparative Example 10") was obtained. Note that the vacuum lamination treatment was not performed on both surfaces.

[0277] In Comparative Example 4 as well, the same evaluation as in Example 1 was conducted. The evaluation results are shown in Table 4 below. As shown in Table 4, the particle diameter of the starch particles on the sheet surface was 2 μm. However, on the sheet surface, slight bleeding occurred and there was a slight stickiness.

[0278] (Comparative Example 5)

[0279] As shown in Table 4 below, plasticized starch was obtained in the same manner as in Example 17, except that 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of glycerin, and 27 parts by mass of water were blended.

[0280] Using 60 parts by mass of the plasticized starch, 40 parts by mass of polypropylene (PM900C, San Allomer Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polypropylene, DuPont Co., Ltd.), a resin composition (hereinafter also referred to as "the resin composition of Comparative Example 5") was obtained. Note that the vacuum lamination treatment was not performed on both surfaces.

[0281] In Comparative Example 5 as well, the same evaluation as in Example 1 was conducted. The evaluation results are shown in Table 4 below. As shown in Table 4, the particle diameter of the starch particles on the sheet surface was 2 μm. However, on the sheet surface, bleeding occurred and it was sticky.

[0282]

Table 4

[0283] Test Example 4: Production and Evaluation of Nonwoven Fabric

[0284] (Example 18)

[0285] The resin composition of Example 1 was supplied to a spunbond molding machine (Japan Steel Works, Ltd.), and the resin composition was discharged from a die hole with a hole diameter D of 0.43 mm and a land length L of 0.75 mm under the condition of a single-hole discharge rate of 13 g / min with a spinning temperature (die temperature) of 200°C to 230°C. A spinning die was used in which the introduction hole located directly above the die hole was a straight hole and the connecting portion between the introduction hole and the die hole was a taper. After the discharged fibrous resin composition was cooled and solidified by blowing cooling air at a temperature of 220°C and a speed of 450 m / min from the outside, it was drawn at a speed of 20 m / min by a rectangular ejector and collected on a moving net to obtain a fiber web.

[0286] Subsequently, the fiber web obtained as described above was thermally bonded at a temperature of 130°C using a pair of upper and lower thermal embossing rolls composed of a metal embossing roll with a diamond pattern engraved on the upper roll and an adhesive area ratio of 25% and a metal flat roll on the lower roll, to obtain a nonwoven fabric with a fiber diameter of 20 μm and a basis weight of 70 g / m 2 ².

[0287] An electron micrograph of the surface of the obtained nonwoven fabric is shown in Fig. 2. As shown in Fig. 2, in the nonwoven fabric formed from the resin composition containing sufficiently plasticized starch, the particle diameter of the starch particles present on the surface of the constituent fibers is about 2 μm, which is sufficiently smaller than the fiber thickness.

[0288] Test Example 5: Production and Molding of Resin Composition (Examples of Films or Sheets)

[0289] (Example 19)

[0290] As a thermoplastic resin, a resin composition was produced using a polyethylene resin instead of a polypropylene resin. As the resin composition, as shown in Table 5 below, as a plasticized starch material, 100 parts by mass of phosphoric acid-crosslinked tapioca starch (T-1, Matsutani Chemical Industry Co., Ltd.), 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, 27 parts by mass of water, and 1 part by mass of succinic acid were prepared. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, the ethylene glycol, the water, and the succinic acid were premixed before being charged into the mixer.

[0291] The mixture obtained by the mixing was a powdery mixture.

[0292] The mixture obtained by the mixing was supplied into a twin-screw extruder (PCM30, Ikegai Corporation), and the mixture was subjected to a kneading treatment.

[0293] The cylinder temperature in the kneading treatment was 110 °C. In the kneading treatment, suction from the vent was performed. After the kneading treatment, the mixture was extruded from the die of the extruder, and an elongated substantially cylindrical plasticized starch (masterbatch) was obtained.

[0294] Regarding the plasticized starch, the presence or absence of bubbles and the durometer hardness were evaluated according to the same criteria as in Example 1 above.

[0295] The evaluation results are as shown in Table 5 below, and no bubbles were formed throughout the plasticized starch. Also, the plasticized starch had a hardness of 27 on the durometer type D.

[0296] 60 parts by mass of the plasticized starch, 40 parts by mass of linear low density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Japan Polyethylene Corporation), 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 resin composition (hereinafter, also referred to as "the resin composition of Example 19") was obtained.

[0297] The resin composition of Example 19 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.

[0298] The particle diameter of the starch particles on the film surface and the presence or absence of bleed were evaluated according to the same method and criteria as in Example 1 above. The evaluation results are as shown in Table 5 below, and an electron micrograph of the obtained film is shown in Fig. 3(a). As shown in Fig. 3(a), the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleed and it was not sticky.

[0299]

Table 5

[0300] (Example 20)

[0301] As shown in Table 5 above, plasticized starch was obtained in the same manner as in Example 19, except that 100 parts by mass of phosphate-crosslinked tapioca starch, 34 parts by mass of glycerin, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. The glycerin and the water were premixed before being charged into the mixer.

[0302] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 20") was obtained in the same manner as in Example 19.

[0303] Using the resin composition of Example 20, inflation molding was performed in the same manner as in Example 19 to obtain a film.

[0304] Also in Example 20, the same evaluation as in Example 19 was performed. The evaluation results are shown in Table 5 above. Regarding the plasticized starch, the same evaluation results as in Example 19 were obtained as shown in Table 5.

[0305] More specifically, the plasticized starch produced in Example 20 had no generation of bubbles throughout and had a hardness of 27 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, bleeding occurred on the film surface and it was sticky.

[0306] (Example 21)

[0307] As shown in Table 5 above, plasticized starch was obtained in the same manner as in Example 19, except that 100 parts by mass of corn starch (product name: Showa Corn Starch, Showa Sangyo Co., Ltd.), 34 parts by mass of glycerin, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. The glycerin and the water were premixed before being charged into the mixer.

[0308] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 21") was obtained in the same manner as in Example 19.

[0309] Using the resin composition of Example 21, inflation molding was carried out in the same manner as in Example 19 to obtain a film.

[0310] Also in Example 21, the same evaluation as in Example 19 was conducted. The evaluation results are shown in Table 5 above. Regarding the plasticized starch, as shown in Table 5, the same evaluation results as in Example 19 were obtained.

[0311] More specifically, the plasticized starch produced in Example 21 had no generation of bubbles throughout and had a hardness of 27 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, bleeding occurred on the film surface, and it was sticky.

[0312] (Example 22)

[0313] As shown in Table 5 above, in the mixer, as the plasticized starch material, 100 parts by mass of phosphate-crosslinked tapioca starch, 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, and 27 parts by mass of water in which CNF (product name: hardwood, Daio Paper Corporation) was suspended at 2% were prepared, and these four components were mixed in the mixer in the same manner as in Example 19 to obtain a mixture.

[0314] Using the mixture, kneading treatment was carried out in the same manner as in Example 19 to obtain plasticized starch containing CNF. Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 22") was obtained in the same manner as in Example 19.

[0315] Using the resin composition of Example 22, inflation molding was carried out in the same manner as in Example 19 to obtain a film.

[0316] Also in Example 22, the same evaluation as in Example 19 was conducted. Regarding the plasticized starch, as shown in Table 5 above, the same evaluation results as in Example 19 were obtained.

[0317] More specifically, the plasticized starch produced in Example 22 had no generation of air bubbles throughout and had a hardness of 26 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and it was non-sticky.

[0318] (Comparative Example 6)

[0319] As shown in Table 5 above, plasticized starch was obtained in the same manner as in Example 19, except that 100 parts by mass of phosphoric acid-crosslinked tapioca starch, 34 parts by mass of ethylene glycol, and 27 parts by mass of water were mixed as the plasticized starch material in the mixer. The ethylene glycol and the water were premixed before being charged into the mixer.

[0320] Using the plasticized starch, a resin composition (hereinafter also referred to as "the resin composition of Comparative Example 6") was obtained in the same manner as in Example 19.

[0321] Using the resin composition of Comparative Example 6, inflation molding was performed in the same manner as in Example 19 to obtain a film.

[0322] Also in Comparative Example 6, the same evaluation as in Example 19 was performed. The evaluation results are shown in Table 5 above. Regarding the plasticized starch, the same evaluation results as in Example 19 were obtained as shown in Table 5.

[0323] More specifically, the plasticized starch produced in Comparative Example 6 had no generation of air bubbles throughout and had a hardness of 27 with a durometer type D. However, regarding the resin composition, the particle diameter of the starch particles on the film surface was as large as 100 μm. An electron micrograph of the obtained film is shown in Fig. 3(b). As shown in Fig. 3(b), in the film containing starch that was not sufficiently plasticized, a large number of starch particles with a particle diameter of about 100 μm were confirmed on the surface.

[0324] Test Example 6: Production and Molding of Resin Composition (Examples of Films or Sheets)

[0325] (Example 23)

[0326] As the thermoplastic resin, a biodegradable resin PBAT (product name: Ecoflex (registered trademark), manufactured by BASF Japan Ltd.) was used to produce a resin composition. As shown in Table 6 below, as the plasticized starch material, 100 parts by mass of phosphoric acid-crosslinked tapioca starch (T-1, Matsutani Chemical Industry Co., Ltd.), 7 parts by mass of glycerin, 27 parts by mass of ethylene glycol, 27 parts by mass of water in which CNF (product name: Hardwood, Oji Paper Co., Ltd.) was suspended at 2% and 1 part by mass of succinic acid were prepared. These five components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, the ethylene glycol, the water in which the CNF was suspended at 2% and the succinic acid were premixed before being charged into the mixer.

[0327] The mixture obtained by the mixing was a powdery mixture.

[0328] The mixture obtained by the mixing was fed into a twin-screw extruder (PCM30, Ikegai Corporation), and the mixture was subjected to a kneading process.

[0329] 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 (masterbatch) was obtained.

[0330] Regarding the plasticized starch, the presence or absence of bubbles and the durometer hardness were evaluated according to the same criteria as in Example 1 above.

[0331] The evaluation results are as shown in Table 6 below, and no bubbles were formed throughout the plasticized starch. Also, the plasticized starch had a hardness of 27 on the durometer type D.

[0332] 60 parts by mass of the plasticized starch and 40 parts by mass of the biodegradable resin 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 resin composition (hereinafter, also referred to as "the resin composition of Example 23") was obtained.

[0333] The resin composition of Example 23 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.

[0334] The particle diameter of the starch particles and the presence or absence of bleed on the film surface were evaluated according to the same method and criteria as in Example 1 above. The evaluation results are as shown in Table 6 below, and the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleed and it was not sticky.

[0335]

Table 6

[0336] (Example 24)

[0337] As shown in Table 6 above, plasticized starch was obtained in the same manner as in Example 23, except that 27 parts by mass of water was mixed instead of water in which 2% of CNF (product name: hardwood, Daio Paper Corporation) was suspended as the plasticized starch material in the mixer. The glycerin, the ethylene glycol, the water, and the succinic acid were premixed before being charged into the mixer.

[0338] Using the plasticized starch, a resin composition (hereinafter, also referred to as "the resin composition of Example 24") was obtained in the same manner as in Example 23.

[0339] Using the resin composition of Example 24, inflation molding was carried out in the same manner as in Example 23 to obtain a film.

[0340] Also in Example 24, the same evaluation as in Example 23 was carried out. The evaluation results are shown in Table 6 above. Regarding the plasticized starch, as shown in Table 6, the same evaluation results as in Example 23 were obtained.

[0341] More specifically, the plasticized starch produced in Example 24 had no generation of bubbles throughout and had a hardness of 27 with a durometer type D. Regarding the resin composition, the particle diameter of the starch particles on the film surface was 2 μm. Also, on the film surface, there was no bleeding and no stickiness.

[0342] Test Example 7: Production and Molding of Resin Composition (Example of Deodorant Sheet)

[0343] (Example 25)

[0344] As the thermoplastic resin, a resin composition was produced using a polyethylene resin. As shown in Table 7 below, as the plasticized starch material, 100 parts by mass of phosphoric acid-crosslinked tapioca starch (T-1, Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of glycerin, 27 parts by mass of water, and 2 parts by mass of deodorant *1 (Fabreeze, manufactured by P&G) were prepared. These four components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, the water, and the deodorant *1 were premixed before being charged into the mixer.

[0345] The mixture obtained by the mixing was a powdery mixture.

[0346] 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.

[0347] 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 (masterbatch) was obtained.

[0348] 30 parts by mass of the plasticized starch, 70 parts by mass of a linear low density polyethylene resin (LLDPE: Linear Low Density Polyethylene, product name UF641, manufactured by Nippon Polyethylene Co., Ltd.), 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 resin composition (hereinafter, also referred to as "the resin composition of Example 25") was obtained.

[0349] The aromaticity of the resin composition was evaluated.

[0350] <Aromaticity of the resin composition> The aromaticity of the resin composition was evaluated by sensory evaluation according to the following method and criteria. The resin composition of Example 25 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 performed at 150°C to 160°C. By the inflation molding, a tubular film with a thickness of 30 to 40 μm was obtained. One end of the tube was tied into a bag shape. What was obtained by dropping 2 or 3 drops of a skatole-indole-containing fragrance onto filter paper with a diameter of 10 cm was put into the obtained bag, and the other end of the tube that was not tied was tied. Seven panelists smelled the odor outside the bag to confirm whether the fragrance of the deodorant remained. The aromaticity of the resin composition was evaluated by sensory evaluation according to the following criteria. A: The fragrance of the deodorant remained strongly, with aroma B: A faint odor of the deodorant remained, with slight aroma C: No odor-removing agent scent remains, no fragrance

[0351] The evaluation results were as shown in Table 7 below, and the resin composition had a fragrance.

[0352]

Table 7

[0353] Each material used in this test example was as follows. Odor-removing agent *1: Commercially available product for fabric, manufactured by P&G Odor-removing agent *2: Commercially available product for odor removal family, manufactured by Universe Development Co., Ltd.

[0354] (Example 26)

[0355] A film was produced and the aromaticity of the resin composition was evaluated in the same manner as in Example 25, except that odor-removing agent *2 (odor removal family, manufactured by Universe Development Co., Ltd.) was used instead of odor-removing agent *1 (fabric, manufactured by P&G). As shown in Table 7 above, the resin composition had a fragrance.

[0356] (Example 27)

[0357] A film was produced and the aromaticity of the resin composition was evaluated in the same manner as in Example 25, except that 34 parts by mass of ethylene glycol and 1 part by mass of maleic acid were blended without blending glycerin. As shown in Table 7 above, the resin composition had a fragrance.

[0358] (Example 28)

[0359] A film was produced and the aromaticity of the resin composition was evaluated in the same manner as in Example 27, except that odor-removing agent *2 (odor removal family, manufactured by Universe Development Co., Ltd.) was used instead of odor-removing agent *1 (fabric, manufactured by P&G). As shown in Table 7 above, the resin composition had a fragrance.

[0360] (Comparative Example 7)

[0361] A film was produced in the same manner as in Example 25 except that deodorant *1 was not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 7 above, the fragrance of the deodorant did not remain in the resin composition.

[0362] (Comparative Example 8)

[0363] As a plasticized starch material, 100 parts by mass of corn starch (product name: Showa Corn Starch, Showa Sangyo Co., Ltd.) was blended, and a film was produced in the same manner as in Example 25 except that deodorant *1 was not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 7 above, the fragrance of the deodorant did not remain in the resin composition.

[0364] (Example 29)

[0365] As shown in Table 8 below, as a plasticized starch material, 100 parts by mass of phosphate-crosslinked tapioca starch (product name: T-1, Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of ethylene glycol, 27 parts by mass of water, 1 part by mass of maleic acid, and 2 parts by mass of deodorant *1 (Fabreeze, manufactured by P&G) were prepared. These five components were mixed in a mixer. The mixing was carried out at room temperature. The ethylene glycol, water, maleic acid, and deodorant *1 were pre-mixed before being charged into the mixer. In addition, Table 8 below shows the parts by mass of other components of the plasticized starch material when the amount of phosphate-crosslinked tapioca starch is 100 parts by mass.

[0366] The mixture obtained by the mixing was a powdery mixture. The powdery mixture was used to obtain plasticized starch in the same manner as in Example 1.

[0367] 30 parts by mass of the plasticized starch, 70 parts by mass of polypropylene (PM900C, San Aromer Co., Ltd.), and 3 parts by mass of a compatibilizer (maleic anhydride-modified polyethylene, DuPont Co., Ltd.) 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 resin composition (hereinafter, also referred to as "the resin composition of Example 29") was obtained.

[0368] The resin composition of Example 29 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 tubular film with a thickness of 30 to 40 μm was obtained.

[0369] Also in Example 29, the same evaluation as in Example 25 was performed. The evaluation results are shown in Table 8 below. As shown in Table 8, the resin composition had an aroma.

[0370]

Table 8

[0371] Each material used in this test example was the same as those used in Table 7.

[0372] (Example 30)

[0373] A film was produced and the aromaticity of the resin composition was evaluated in the same manner as in Example 29, except that deodorant *2 was used instead of deodorant *1. As shown in Table 8 above, the resin composition had an aroma.

[0374] (Example 31)

[0375] A film was produced in the same manner as in Example 30 except that 1 part by mass of the deodorant *2 was blended, and the aromaticity of the resin composition was evaluated. As shown in Table 8 above, the resin composition had an aroma.

[0376] (Comparative Example 9)

[0377] A film was produced in the same manner as in Example 29 except that the deodorant *1 was not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 8 above, the resin composition did not have an aroma.

[0378] (Comparative Example 10)

[0379] As a plasticized starch material, 100 parts by mass of corn starch (product name: Showa Corn Starch, manufactured by Showa Sangyo Co., Ltd.) was blended, 34 parts by mass of glycerin was blended instead of ethylene glycol, and a film was produced in the same manner as in Example 29 except that maleic acid and the deodorant *1 were not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 8 above, the resin composition did not have an aroma.

[0380] (Example 32)

[0381] As a thermoplastic resin, a resin composition was produced using biodegradable resin PBAT (product name: Ecoflex (registered trademark), manufactured by BASF Japan Ltd.). As shown in Table 9 below, as a plasticized starch material, 100 parts by mass of phosphate-crosslinked tapioca starch (T-1, manufactured by Matsutani Chemical Industry Co., Ltd.), 34 parts by mass of glycerin, 27 parts by mass of water, and 2 parts by mass of deodorant *1 (Fabreeze, manufactured by P&G) were prepared. These four components were mixed in a mixer. The mixing was carried out at room temperature. The glycerin, the water, and the deodorant *1 were premixed before being charged into the mixer.

[0382] The mixture obtained by the mixing was a powdery mixture.

[0383] The mixture obtained by the mixing was fed into a twin-screw extruder (PCM30, manufactured by Ikegai Corporation), and the mixture was subjected to a kneading process.

[0384] 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 (masterbatch) was obtained.

[0385] 30 parts by mass of the plasticized starch and 70 parts by mass of the biodegradable resin 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 resin composition (hereinafter, also referred to as "the resin composition of Example 32") was obtained.

[0386] The resin composition of Example 32 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 tubular film with a thickness of 30 to 40 μm was manufactured, and the aromaticity of the resin composition was evaluated. The evaluation results are as shown in Table 9 below, and the resin composition had an aroma.

[0387]

Table 9

[0388] Each material used in this test example was the same as those used in Table 8.

[0389] (Example 33)

[0390] A film was manufactured and the aromaticity of the resin composition was evaluated in the same manner as in Example 32, except that deodorant *2 was used instead of deodorant *1. As shown in Table 9 above, the resin composition had an aroma.

[0391] (Example 34)

[0392] A film was produced in the same manner as in Example 32, except that 34 parts by mass of ethylene glycol was blended instead of glycerin and an additional 1 part by mass of maleic acid was blended, and the aromaticity of the resin composition was evaluated. As shown in Table 9 above, the resin composition had an aroma.

[0393] (Example 35)

[0394] A film was produced in the same manner as in Example 34, except that deodorant *2 was used instead of deodorant *1, and the aromaticity of the resin composition was evaluated. As shown in Table 9 above, the resin composition had an aroma.

[0395] (Comparative Example 11)

[0396] A film was produced in the same manner as in Example 32, except that deodorant *1 was not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 9 above, the resin composition did not have an aroma.

[0397] (Comparative Example 12)

[0398] A film was produced in the same manner as in Example 35, except that deodorant *1 was not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 9 above, the resin composition did not have an aroma.

[0399] (Comparative Example 13)

[0400] As a plasticized starch material, 100 parts by mass of corn starch (product name: Showa Corn Starch, Showa Sangyo Co., Ltd.) was blended, and a film was produced in the same manner as in Example 32, except that deodorant *1 was not blended, and the aromaticity of the resin composition was evaluated. As shown in Table 9 above, the resin composition did not have an aroma.

Claims

1. The plasticized starch has a plasticized starch material containing starch, a polar organic compound capable of gelatinizing or plasticizing the starch at a temperature higher than room temperature, and water (excluding the equilibrium moisture contained in the starch), and has a hardness of 20 or more in durometer type D.

2. The plasticized starch of claim 1, further comprising an organic acid.

3. The plasticized starch described in claim 2, wherein the organic acid is a carboxylic acid having two or more carboxyl groups.

4. The plasticized starch according to any one of claims 1 to 3, which does not have a foamed portion.

5. The plasticized starch according to any one of claims 1 to 4, which is used for producing a plasticized starch-containing resin composition containing starch having a particle diameter of 2 μm or less as measured by a secondary electron image taken with a scanning electron microscope.

6. The plasticized starch according to any one of claims 1 to 5, which has a cylindrical (strand) or pellet-like shape.

7. The plasticized starch described in any one of claims 1 to 6, further containing a functional agent.

8. A mixing step of mixing starch, a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and water (excluding the equilibrium moisture contained in the starch); and The method for producing plasticized starch includes a plasticizing step of plasticizing the starch by heating the mixture obtained in the mixing step, thereby producing a plasticized starch having a hardness of 20 or more in durometer type D.

9. The method for producing plasticized starch described in claim 8, further comprising mixing an organic acid in the mixing step.

10. The method for producing plasticized starch described in claim 9, wherein the organic acid is a carboxylic acid having two or more carboxyl groups.

11. The method for producing a plasticized starch according to any one of claims 8 to 10, further comprising mixing a functional agent in the mixing step.

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