JP7246691B2 - resin composition - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies TOKYO PACK 2018 (2018 Tokyo International Packaging Exhibition) Exhibition date October 2, 2018

The present invention relates to a resin composition containing a plasticized starch material, a film or sheet formed from the resin composition, the plasticized starch material, a method for producing the resin composition, and a method for producing the plasticized starch material. .

Plastic moldings containing biomass materials are attracting attention. Since the plastic molded product contains a biomass material as an alternative to a petroleum-based material, it is possible to reduce CO2 emitted during combustion. Examples of biomass materials include waste biomass (food waste, livestock excrement, construction waste, waste paper, etc.), unused biomass (non-edible parts of agricultural crops, forest residue, etc.), and resource grains. can.

Regarding plastic molded products containing biomass materials, for example, Patent Document 1 below discloses 50 to 70% by weight of starch, 20 to 40% by weight of thermoplastic resin, and 0.1 to 10% by weight of melting point of 60 to 60%. Contains a low melting point additive of 100 ° C. and a high melting point additive of 1 to 15% by weight of a melting point of 100 ° C. to 150 ° C., has a core part of a thermoplastic resin granule, and has a core part surface of the granule Starch/resin composite molding obtained by melt-extrusion of starch/resin composite intermediate granules as a raw material, provided with a coating layer of granules containing starch containing at least a low-melting-point additive, adhered to the surface by at least a high-melting-point additive. A processed material is disclosed.

JP 2018-104629 A

If the ratio of biomass materials contained in plastic molded products can be increased, it can contribute to the reduction of the amount of CO2 emitted. On the other hand, increasing the proportion of biomass material can affect the quality of plastic moldings. Accordingly, an object of the present invention is to provide a new means for providing a plastic molded article having a high biomass material content and good quality.

The present inventors have found that a particular plasticized starch material can provide plastic moldings with a high biomass content and good quality.

That is, the present invention includes a plasticized starch material and a thermoplastic resin, the plasticized starch material includes a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch, and the starch is a paste. The polar organic compound capable of gelatinizing or plasticizing contains at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature, and the plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer. Provided is a resin composition having a hardness of 40 or less.
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature may be a compound having at least one amide group .
The plasticized starch material may be free of foamed portions.
The polar organic compound contains a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature, and the polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature is It may contain at least one compound selected from polyhydric alcohols.
The plasticized starch may be a plasticized starch or a modified plasticized starch.
The thermoplastic resin may be a polyolefin-based resin, a polyester-based resin, or a mixture of these resins.
The resin composition may further include cellulose nanofibers.
In addition, the present invention
comprising a plasticized starch material and a thermoplastic resin;
the plasticized starch material comprises a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less,
The thermoplastic resin is a polyolefin resin,
A resin composition is also provided.
In addition, the present invention
comprising a plasticized starch material and a thermoplastic resin;
the plasticized starch material comprises a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less,
The thermoplastic resin is a polyolefin-based resin, a polyester-based resin, or a mixture of these resins.
A resin composition is also provided.
The plasticized starch material may have no foamed areas.
The plasticized starch may be a plasticized starch or a modified starch plasticized product.

The present invention also provides a film or sheet comprising a layer formed from the resin composition.
The present invention also provides a film or sheet comprising a layer formed from the resin composition and having a surface with an average roughness (Ra) of 2 μm or less as measured according to JIS B0031.
The present invention also provides a porous film or sheet formed from the resin composition.
The present invention also provides a film or sheet formed from the resin composition and permeable to air but impermeable to water.

The present invention comprises a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch, wherein the polar organic compound capable of gelatinizing or plasticizing the starch gelatinizes or plasticizes the starch at room temperature. Also provided is a plasticized starch material comprising at least possible polar organic compounds and having a Type A durometer of 20 or greater and a Type D durometer of 40 or less.
In addition, the present invention
comprising a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less;
Also provided is a plasticized starch material for use in blending with a polyolefin-based resin to produce a resin composition.
In addition, the present invention
comprising a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
A type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less, and
Used to produce a resin composition by mixing with a polyolefin resin or polyester resin or a mixture of these resins
A plasticized starch material is also provided.

The present invention is a first mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch with 100 parts by mass of starch, wherein the polar organic compound is The starch is plasticized by heating the mixture obtained by the first mixing step and the first mixing step to a temperature of 120° C. to 150° C., which contains at least a polar organic compound capable of gelatinizing or plasticizing starch. to obtain a plasticized starch material, wherein the plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less; A method of making a resin composition is also provided, comprising a second mixing step of mixing the starch material and the thermoplastic resin to obtain the resin composition.
In addition, the present invention
A first mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch and having an SP value of 10 to 25 with respect to 100 parts by mass of starch, wherein the polar The first mixing step, wherein the organic compound includes at least a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature;
a plasticizing step of plasticizing the starch to obtain a plasticized starch material by heating the mixture obtained from the first mixing step to a temperature of 120° C. to 150° C., wherein the plasticized starch material is type A; the plasticizing step having a durometer hardness of 20 or more and a type D durometer hardness of 40 or less;
A second mixing step of mixing the plasticized starch material and the thermoplastic resin to obtain a resin composition
including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The thermoplastic resin is a polyolefin resin,
A method of making a resin composition is also provided.
In addition, the present invention
A first mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch and having an SP value of 10 to 25 with respect to 100 parts by mass of starch, wherein the polar The first mixing step, wherein the organic compound includes at least a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature;
a plasticizing step of plasticizing the starch to obtain a plasticized starch material by heating the mixture obtained from the first mixing step to a temperature of 120° C. to 150° C., wherein the plasticized starch material is type A; the plasticizing step having a durometer hardness of 20 or more and a type D durometer hardness of 40 or less;
A second mixing step of mixing the plasticized starch material and the thermoplastic resin to obtain a resin composition
including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The thermoplastic resin is a polyolefin-based resin, a polyester-based resin, or a mixture of these resins.
A method of making a resin composition is also provided.

The present invention is a mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch with 100 parts by mass of starch, wherein the polar organic compound dissolves starch at room temperature. A plasticized starch material by plasticizing the starch by heating the mixture obtained by the mixing step and the mixture obtained by the mixing step to a temperature of 120° C. to 150° C., which contains at least a polar organic compound capable of gelatinization or plasticization A method for producing a plasticized starch material having a Type A durometer hardness of 20 or greater and a Type D durometer hardness of 40 or less is also provided.
In addition, the present invention
A mixing step of mixing 100 parts by mass of starch with 20 parts by mass to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch and having an SP value of 10 to 25, wherein the polar organic compound contains at least a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature, and
a plasticizing step of heating the mixture obtained in the mixing step to a temperature of 120° C. to 150° C. to plasticize the starch to obtain a plasticized starch material;
including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
A method for producing a plasticized starch material having a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less and used to produce a resin composition by mixing with a polyolefin resin is also provided.
In addition, the present invention
A mixing step of mixing 20 parts by mass to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch with 100 parts by mass of starch, wherein the polar organic compound gelatinizes or plasticizes starch at room temperature. the mixing step comprising at least a polar organic compound capable of gelatinizing starch and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature; and
a plasticizing step of heating the mixture obtained in the mixing step to a temperature of 120° C. to 150° C. to plasticize the starch to obtain a plasticized starch material;
including
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
A plasticizer that has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less and is used to produce a resin composition by mixing with a polyolefin resin or polyester resin or a mixture of these resins A method for producing a modified starch material is also provided.

ADVANTAGE OF THE INVENTION By this invention, the content rate of the biomass material in a plastic molded article can be increased, and good quality can be given to the said 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 herein.

1 is a photograph of a plasticized starch material; It is an electron micrograph of the surface and cross section of the film. It is a graph which shows the measurement result of the average roughness (Ra) of the film surface. The unit of the vertical axis is μm. It is a graph which shows the measurement result of the maximum height (Ry) of the film surface. The unit of the vertical axis is μm. It is a figure which shows the measurement result of tensile elongation. It is a figure which shows the measurement result of tensile strength. 1 is a photograph of a plasticized starch material;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail. It should be noted that the embodiments described below are examples of representative embodiments of the present invention, and the present invention is not limited to these embodiments.

1. resin composition

The resin composition of the present invention comprises a plasticized starch material and a thermoplastic resin, wherein the plasticized starch material comprises a plasticized starch and at least one polar organic compound capable of gelatinizing or plasticizing the starch. wherein the polar organic compound capable of gelatinizing or plasticizing starch includes at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature, and the plasticized starch material has a type A durometer hardness of 20 and a type D durometer hardness of 40 or less.

The resin composition of the present invention contains the plasticized starch material and the thermoplastic resin in a ratio of, for example, 20 parts by mass: 80 parts by mass to 80 parts by mass: 20 parts by mass, preferably 30 parts by mass: 70 parts by mass to It can be contained in a ratio of 80 parts by weight:20 parts by weight, and more preferably in a ratio of 50 parts by weight:50 parts by weight to 80 parts by weight:20 parts by weight. The resin composition having this ratio has a high degree of biomass. The plasticized starch material can thus increase the biomass content of the resin composition, and even with the increased biomass content, the resin composition still has good quality.

In this specification, the degree of biomass is a value calculated by the following formula.
Formula: Degree of biomass (%) = “dry weight of biomass contained in resin composition” ÷ “dry weight of resin composition” × 100
The resin composition of the present invention or a molded article (e.g., film, sheet, etc.) formed from the resin composition is, for example, 20% or more, preferably 30% or more, more preferably 40% or more, more preferably 50% or more. , more preferably 60% or more, still more preferably 70% or more. The upper limit of the biomass degree may be, for example, 90% or less, 80% or less, or 70% or less.

The starch that constitutes the plasticized starch material is plasticized. Thereby, the surface of the molded article formed from the resin composition can be made smooth. In addition, for example, the physical properties of a layer formed from a resin composition or the physical properties (eg, tensile elongation, etc.) of a film or sheet containing the layer can be improved.

In addition, the plasticized starch material can be produced so as to suppress coloring and/or generation of odor caused by heating starch. That is, the plasticized starch material may have no such color and/or odor, or may have little if any such color and/or odor. For example, the plasticized starch material can be transparent and/or odorless. Therefore, the resin composition obtained by mixing the plasticized starch material with the thermoplastic resin may not have the coloration and/or odor, or may have the coloration and/or odor. there are few of them.
These improvements in coloration and/or odor are mainly due to the polar organic compound capable of gelatinizing or plasticizing the starch that constitutes the plasticized starch material, and in particular the polar organic compound gelatinizes the starch at room temperature. or due to the inclusion of a plasticizable compound.

There are several compounds other than polar organic compounds that can gelatinize or plasticize starch at room temperature. Substances capable of gelatinizing or plasticizing starch at room temperature include, for example, strong alkalis (such as sodium hydroxide), salts (such as calcium chloride), and anions or cations (such as Na ⁺ and Li ⁺ ). . However, when the starch is gelatinized or plasticized with a strong alkali, the plasticized starch material becomes strongly alkaline, which is dangerous and difficult to handle. When salts are used, an exothermic reaction occurs with gelatinization and the temperature rises, so the plasticized starch material is colored. When starch is gelatinized using anions and cations, the starch is gelatinized, but the plasticized starch material produced is discolored.
In the present invention, a polar organic compound capable of gelatinizing or plasticizing starch is used, and the polar organic compound includes at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature. This eliminates or reduces the extent of the inconveniences described above for other compounds.

In addition, by using the plasticized starch material, molded articles (such as films and sheets) having a high biomass content in the resin composition and good quality (such as surface smoothness, low coloration, and low odor). can be manufactured. For example, since the resin composition of the present invention does not contain granular starch, even if a thin film or sheet is formed from the resin composition, the grain shape 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 formed from the resin composition does not have a granular shape on its surface.
Furthermore, the resin composition containing the plasticized starch material can also be used to form a porous film or sheet of good quality. The present invention can provide a resin composition and a molded article having such good properties.

Moreover, by using the plasticized starch material, the plasticized starch material and the thermoplastic resin can be mixed at a low temperature, and the resin composition can be molded at a low temperature. Thereby, the coloring and/or odor of the molded article can be reduced.

In addition, since the resin composition of the present invention contains the plasticized starch material, it is possible to impart transparency to the resin composition and molded articles (for example, films or sheets) formed from the resin composition. In addition, by including the plasticized starch material in the resin composition of the present invention, the surface of the resin composition and molded articles (for example, films or sheets) formed from the resin composition can be made smooth.

The resin composition of the present invention contains the plasticized starch material and the thermoplastic resin as main components. The total content of the plasticized starch material and the thermoplastic resin in the resin composition of the present invention is, for example, 80% by mass or more, preferably 85% by mass or more, relative to the mass of the resin composition, It is more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

The resin composition of the present invention will be described in more detail below.

[Plasticized starch material]

By employing the plasticized starch material as the biomass material in the resin composition, the degree of biomass (content ratio of biomass material) of the resin composition can be increased.
For example, if the content of conventionally known starch materials (e.g., non-gelatinized starch materials, etc.) in the resin composition is 50% by mass or more, the resin composition may not be molded, or , may be mouldable but not of good quality. Specifically, when inflation molding is performed using the resin composition, the resin composition may not swell, or foaming may occur in the resin composition. Furthermore, even if the film swells, the film obtained by the molding has poor stretchability, so the film is easily cut. Also, the resin composition may not have excellent strength.
Since the resin composition of the present invention contains the plasticized starch material, it has excellent moldability and is suitable for molding films or sheets, for example. That is, the resin composition of the present invention can be used for forming films or sheets. Moreover, since the resin composition of the present invention contains the plasticized starch material, it has excellent physical properties (eg, tensile elongation).

The plasticized starch material used in the present invention has a Type A durometer hardness of 20 or more and a Type D durometer hardness of the same starch material is 40 or less. In the present invention, durometer hardness is measured according to JIS K 6253. In addition, when the type A durometer hardness is more than 90, the type D durometer hardness is used, and as described above, the lower limit of the numerical range of hardness is defined by the type A durometer hardness and the upper limit is the type D Defined by durometer hardness.
From the standpoint of moldability of the resin composition, the plasticized starch material may have a type A durometer hardness of 22 or higher, more preferably 25 or higher, and even more preferably 28 or higher. The plasticized starch material may more preferably have a Type D durometer hardness of 35 or less, more preferably a Type D durometer hardness of 30 or less.
A plasticized starch material having a hardness within the numerical range improves the moldability of the molded article (eg, ease of inflation molding) and/or the appearance of the molded article. By using the plasticized starch material, it is possible to produce molded articles that do not show, for example, fish eyes or foreign bodies. If the type D durometer hardness of the plasticized starch material is greater than 40, for example, the resin composition containing the plasticized starch material may not be suitable for molding, for example, inflation molding may not be possible.
Also, the plasticized starch material used in the present invention does not have foamed portions. Such foaming can occur, for example, due to evaporation of volatile components in the production of the plasticized starch material. A resin composition made using a plasticized starch material having foamed portions may have poor moldability, and furthermore, the appearance of the resin composition may be poor.

The plasticized starch material contained in the resin composition of the present invention may be a material containing plasticized starch as a main component. The content of the plasticized starch in the plasticized starch material may be, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, relative to the mass of the plasticized starch material. The content of the plasticized starch in the plasticized starch material may be, for example, 99.5% by mass or less, 99% by mass or less, or 98% by mass or less with respect to the mass of the plasticized starch material. The content of the plasticized starch may be measured by TG measurement (thermogravimetric analysis) at 150°C. Specifically, the content ratio may be determined based on the amount of change in mass measured using a TG measurement device (STA7200, Hitachi High-Tech Science Co., Ltd.). The amount of mass change corresponds to the reduction in volatile components, which corresponds to the amount of polar organic compounds capable of gelatinizing or plasticizing the starch. Therefore, the content ratio of plasticized starch in the plasticized starch material is obtained by the following formula: (content ratio of plasticized starch in the plasticized starch material (unit: mass%)) = (start of measurement of mass change amount (mass after measurement)/(mass before measurement of mass change)×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.

As used herein, the term "polar organic compound capable of gelatinizing or plasticizing starch" refers to a polar organic compound capable of gelatinizing or plasticizing starch upon contact with the starch. Organic compounds known in the art may be used as polar organic compounds capable of gelatinizing or plasticizing the starch.
The polar organic compound capable of gelatinizing or plasticizing starch is preferably a compound having an SP value of 10 to 25, more preferably 12 to 22, more preferably 13 to 21, still more preferably 14 to 20. you can A polar organic compound having an SP value within this numerical range is suitable as a component of the plasticized starch material for achieving the effects of the present invention. For example, a compound having an SP value within this numerical range can reduce the coloring and/or odor of the plasticized starch material, thereby reducing the coloring and/or odor of the resin composition of the present invention. can.

The polar organic compound capable of gelatinizing or plasticizing starch is a polar organic compound that is not capable of gelatinizing or plasticizing starch at room temperature but is capable of gelatinizing or plasticizing starch at a temperature higher than room temperature, and starch at room temperature. and polar organic compounds that can be gelatinized or plasticized. In this specification, the former is also referred to as "a polar organic compound capable of gelatinizing or plasticizing starch at high temperature", and the latter is also referred to as "a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature". The latter are compounds that can gelatinize or plasticize starch at normal temperature and also gelatinize or plasticize starch at elevated temperatures. For example, the starch is not gelatinized or plasticized by contacting the polar organic compound with starch at room temperature for 1 hour, but the starch is gelatinized or plasticized by contacting the polar organic compound with starch at high temperature for 1 hour. When gelatinized, the polar organic compound is "capable of gelatinizing or plasticizing starch at elevated temperatures." The polar organic compound capable of gelatinizing or plasticizing starch is any of a polar organic compound capable of gelatinizing starch, a polar organic compound capable of plasticizing starch, and a polar organic compound capable of gelatinizing and plasticizing starch. may be
That is, in the present specification, "a polar organic compound capable of gelatinizing or plasticizing starch" includes "a polar organic compound capable of gelatinizing or plasticizing starch at high temperature" and "a polar organic compound capable of gelatinizing or plasticizing starch at room temperature." polar organic compounds that can be
In this specification, a temperature higher than normal temperature (also referred to as “high temperature”) refers to a temperature achieved by heat treatment. The high temperature is, for example, 50° C. or higher, preferably 60° C. or higher, preferably 80° C. or higher, more preferably 100° C. or higher.
In this specification, normal temperature refers to the temperature when heat treatment is not performed. Normal temperature is, for example, less than 50°C, preferably 10 to 40°C, more preferably 15 to 35°C, still more preferably 20 to 30°C.

In the present invention, the polar organic compound capable of gelatinizing or plasticizing starch, which constitutes the plasticized starch material, includes at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature. A polar organic compound capable of gelatinizing or plasticizing the starch at ambient temperature imparts good qualities to the resin composition, such as reducing coloration and/or odor. Among polar organic compounds capable of gelatinizing or plasticizing starch at normal temperature, polar organic compounds capable of gelatinizing starch at normal temperature are particularly preferred. By gelatinizing the starch, the starch can be plasticized to form a plasticized starch.
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature is preferably a compound having at least one amide group (e.g., one, two, or three amide groups ), such as formamide (SP value 19 .2), N,N dimethylformamide (SP value: 12.1), and urea.
From the viewpoint of ease of mixing with starch, more preferably, the polar organic compound capable of gelatinizing or plasticizing starch at room temperature is liquid at room temperature, such as formamide or N,N dimethylformamide. For example, formamide is a compound that can gelatinize starch at room temperature. The plasticized starch material containing the polar organic compound capable of gelatinizing or plasticizing the starch at room temperature improves the moldability of the resin composition, making it easier to form, for example, pellets of the resin composition. Moreover, the resin composition containing a plasticized starch material containing a polar organic compound capable of gelatinizing or plasticizing starch at room temperature can also be applied to inflation molding.

In a preferred embodiment of the present invention, the polar organic compound capable of gelatinizing or plasticizing starch at room temperature may be formamide. The inclusion of formamide in the plasticized starch material particularly improves the moldability of the resin composition (eg, ease of pelletization and suitability for inflation molding as discussed above). In addition, since the plasticized starch material contains formamide, the coloring of the plasticized starch material can be further reduced, and the plasticized starch material can be made translucent, for example.

The polar organic compound capable of gelatinizing or plasticizing starch at room temperature is preferably 10 to 25, more preferably 12 to 24, more preferably 14 to 23, still more preferably 16 to 22, particularly preferably 18 to It may be a compound with an SP value of 22. A compound having an SP value within this numerical range is suitable as the polar organic compound capable of gelatinizing or plasticizing starch at room temperature.

Preferably, the total content of the polar organic compounds capable of gelatinizing or plasticizing the starch in the plasticized starch material is, for example, 30% by mass or less, preferably 20% by mass, relative to the mass of the plasticized starch material. % or less, more preferably 10 mass % or less. The total content of polar organic compounds capable of gelatinizing or plasticizing the starch in the plasticized starch material is, for example, 0.05% by mass or more and 0.1% by mass with respect to the mass of the plasticized starch material. or more, or 0.2% by mass or more. The total content ratio is the sum of the content ratio of the polar organic compound capable of gelatinizing or plasticizing starch at high temperature and the content ratio of the polar organic compound capable of gelatinizing or plasticizing starch at normal temperature. The total content of polar organic compounds capable of gelatinizing or plasticizing the starch is calculated by subtracting the content of gelatinized starch measured by the TG measurement described above from 100% by mass.

In one embodiment of the present invention, the polar organic compound capable of gelatinizing or plasticizing starch is a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at high temperature. Includes both polar organic compounds. Thus, both of these two polar organic compounds constitute part of the plasticized starch material. The combination of these two polar organic compounds provides a plasticized starch material that is more suitable for mixing with thermoplastic resins. The polar organic compound capable of gelatinizing or plasticizing starch at temperatures above ambient temperature is preferably liquid at ambient temperature. This facilitates mixing with starch.

For example, the polar organic compound capable of gelatinizing or plasticizing starch further includes a polar organic compound capable of gelatinizing or plasticizing starch at a temperature (high temperature) higher than room temperature, and gelatinizes starch at the high temperature. Alternatively, the plasticizable polar organic compound may be one or more compounds selected from polyhydric alcohols. A combination of these compounds with the polar organic compound capable of gelatinizing or plasticizing the starch at normal temperature is particularly suitable for plasticizing the starch mixed in the resin composition.

The polyhydric alcohol is preferably a polyhydric alcohol having 2 to 5 carbon atoms, more preferably a polyhydric alcohol having 2 to 4 carbon atoms. Said polyhydric alcohol preferably has 2 to 5 OH groups, more preferably 2 to 4 OH groups.
Examples of the polyhydric alcohol include glycerin (SP value: 16.5) and glycol. Examples of the glycol include ethylene glycol (SP value: 14.2), diethylene glycol (SP value: 14.6), and propylene glycol.
The polyhydric alcohol may be one or a combination of two or more preferably selected from glycerin, ethylene glycol, diethylene glycol, and propylene glycol.

The plasticized starch material may further comprise a polyhydric alcohol ester. A polyhydric alcohol ester can be a compound in which a fatty acid is ester-bonded to at least one of the OH groups contained in the polyhydric alcohol. The polyhydric alcohol may be as described above. For example, the polyhydric alcohol can be a compound in which fatty acids are ester-bonded to one, two, or three of the three OH groups of glycerin (referred to as monoglycerides, diglycerides, or triglycerides, respectively). More preferably, said polyhydric alcohol ester is a monoglyceride. The fatty acid may be, for example, a fatty acid having 14-22 carbon atoms, more preferably 16-20 carbon atoms. For example, the polyhydric alcohol ester may be a monoglyceride in which a fatty acid having 14 to 22 carbon atoms, more preferably 16 to 20 carbon atoms, is ester-bonded to one OH group of glycerin. Examples of such monoglycerides include glycerin monostearate. The plasticized starch material of the present invention contains, for example, 0.1 to 3 parts by mass, preferably 0.5 to 2 parts by mass of the monoglyceride (eg, glycerin monostearate) per 100 parts by mass of starch. sell. By including a monoglyceride (particularly glycerin monostearate) in an amount within this numerical range, adhesion between pelletized plasticized starch materials can be prevented, resulting in improved handling of the material.

Said plasticized starch material may further comprise a surfactant. Such surfactants may be, for example, stearates and/or sorbitates. The surfactant can function as a lubricant.

In one embodiment of the present invention, the plasticized starch material comprises a polyhydric alcohol in addition to the plasticized starch and the polar organic compound capable of gelatinizing or plasticizing the starch at normal temperature. The polyhydric alcohol can be, for example, glycerin alone or a combination of glycerin and ethylene glycol.

In another embodiment of the present invention, the plasticized starch material comprises a polyhydric alcohol and a polyhydric alcohol ester in addition to the plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch at ambient temperature. The polyhydric alcohol can be, for example, glycerin alone or a combination of glycerin and ethylene glycol. The polyhydric alcohol ester may be a monoglyceride, in particular glycerol monostearate.

The plasticized starch constituting the plasticized starch material is starch gelatinized or plasticized by heating starch in the presence of a polar organic compound capable of gelatinizing or plasticizing the starch. The gelatinization or plasticization may be brought about, for example, by breaking of intermolecular bonds (mainly hydrogen bonds) by polar organic compounds that can be gelatinized or plasticized at room temperature, or gelatinization or plasticization at high temperatures. It may also be brought about by breaking of intermolecular bonds (mainly hydrogen bonds) by heating in the presence of a polar organic compound that can be oxidized. The plasticized starch 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.
It is considered that the plasticization also contributes to the improvement of the biomass content of the resin composition of the present invention. For example, in a molded article formed from a resin composition containing starch that has not been plasticized, particles of the starch tend to appear on the surface of the molded article. The starch particles have a particle size of, for example, about 20 μm. Therefore, for example, when forming a film using a resin composition containing starch that has not been plasticized, in order to prevent the particle shape of the starch from appearing on the surface of the film, the amount of the starch in the resin composition is The content ratio is limited to, for example, about 30% by mass at maximum with respect to the amount of the resin composition. In addition, when the thickness of the film is about 20 μm or less, the particles of the starch are conspicuously present on the film surface. On the other hand, since the starch contained in the resin composition of the present invention is plasticized, the shape of the starch is less likely to appear on the surface of the resin composition. Therefore, the content of starch in the resin composition of the present invention can be more than 30% by mass, for example, more than 60%, more particularly more than 60%, based on the mass of the resin composition. may be 70% or more. Even if the starch content is high, the surface of the resin composition or molded article is smooth.

The starch used in the present invention includes underground starch and ground starch.
Subterranean starch is starch accumulated underground, for example, starch accumulated in rhizomes or roots. Examples of underground starch include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, arrowroot starch, and bracken starch.
Terrestrial starch is starch accumulated on the ground, for example, starch accumulated in seeds and the like. Ground-based starches include, but are not limited to, corn starch, barley starch, and rice starch.
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 present invention may be a modified starch (ie modified starch), particularly a modified underground starch. Modified can be plasticized at lower temperatures compared to unmodified starch. Therefore, odor and/or coloration associated with heating during production of plasticized starch can be suppressed.

The starch used in the present invention may preferably contain equilibrium moisture. The amount of equilibrium moisture is, for example, 10% to 15% by weight, preferably 10% to 14% by weight, more preferably 10% to 13% by weight, even more preferably 11% to 13% by weight, based on the starch weight. It can be mass %. It is preferred to use starch or modified starch with an equilibrium moisture content within the above numerical range for producing plasticized starch material according to the present invention. If starch without equilibrium moisture is used, the starch may not be plasticized.

According to one embodiment of the present invention, the plasticized starch is a plasticized starch or a modified starch plasticized. For example, the starch can be, for example, corn starch or tapioca starch.
The plasticized starch is more preferably, for example, one selected from tapioca starch (cassava starch), potato starch, sweet potato starch, arrowroot starch, and bracken starch, or a plasticized product of a combination of two or more starches, or It can be a plasticizer of said one modified starch or a combination of said two or more modified starches. Even more preferably, the plasticized starch is a plasticized tapioca starch or a modified plasticized tapioca starch. These plasticized materials are particularly preferred from the viewpoint of reducing the odor of the plasticized starch material and the resin composition of the present invention.

According to one embodiment of the present invention, said plasticized starch material may comprise cellulose nanofibers (hereinafter also referred to as CNF). Dispersing CNFs in thermoplastics is often difficult. The plasticized starch material can easily disperse CNF in the material, and the plasticized starch material containing CNF can be easily mixed with the thermoplastic resin. Therefore, the CNF can be easily dispersed in the thermoplastic resin by the plasticized starch material. By including CNF in the resin composition of the present invention, the rigidity of a molded article formed from the resin composition can be increased. In addition, in the embodiment in which the plasticized starch material contains CNF, CNF may not be directly added to the thermoplastic resin, but CNF may be further added to the thermoplastic resin.

The benefits of the plasticized starch material comprising CNF are described in more detail below.
CNF is hydrophilic. CNF is generally produced by pulverizing a cellulose material with water to make it nano, so it is dispersed in water.
CNF is used, for example, to increase the strength of thermoplastic resins. However, mixing CNFs, which are hydrophilic, with thermoplastics can be difficult because thermoplastics are often hydrophobic. Therefore, for example, mixing CNF (in particular, powdery CNF) obtained by denaturing CNF to make it hydrophobic is mixed with a thermoplastic resin. A TENPO oxidation method, for example, can be used for the hydrophobization. Moreover, mixing the CNF dispersion obtained by solvent-substituting the water in which CNF is dispersed with a liquid resin (for example, an epoxy resin or a vinyl chloride resin) is also performed. Alternatively, the cellulose material is directly pulverized by an extruder without being pulverized with water, and the CNF obtained as a result of the pulverization is mixed with a thermoplastic resin. Such mixing techniques can be costly (eg, labor, expense, or time). Therefore, it is desirable to use the CNF dispersed in water as it is.
Moreover, 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.
In addition, 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 CNF aqueous dispersion has a high water content ratio. Therefore, it is often difficult to mix an aqueous dispersion of CNF with a thermoplastic resin.
As described above, the plasticized starch material used in the present invention can easily disperse CNF in the material, and the plasticized starch material containing CNF and the thermoplastic resin are easily mixed. make it possible.
CNF dispersed in water can be used as the CNF. Even if an aqueous dispersion of CNF is used, by using an aqueous dispersion of CNF in the production of the plasticized starch material, CNF can be easily incorporated into the thermoplastic resin without using the mixing technique described above. can be dispersed.
Also, when the plasticized starch material containing CNF is mixed with a thermoplastic resin, the CNF is well dispersed in the thermoplastic resin. Therefore, both tensile elongation and tensile strength of the thermoplastic resin can be improved.
In addition, when the biomass content or the biodegradable resin content in the resin composition increases, the tensile strength of the resin composition may decrease. By mixing the plasticized starch material containing CNF as described above with a thermoplastic resin, the problem of reduction in tensile strength due to a high biomass content or biodegradable resin content in the resin composition is solved. be able to. Furthermore, other effects provided by CNF may also be exhibited in the resin composition.
Examples of CNF contained in the plasticized starch material include CNF dispersed in water produced by the general production method described above. In addition to the water-dispersed CNF, modified CNF, such as the hydrophobized CNF described above, may be included in the plasticized starch material. Powdered CNF can also be dispersed in the plasticized starch material if dispersed in water. Thus, the plasticized starch material is capable of dispersing various CNFs throughout the material. CNF dispersed in water is preferable as the CNF dispersed in the plasticized starch material from the viewpoint of cost and ease of handling. The CNF dispersed in water is also particularly easy to introduce into the plasticized starch material manufacturing facility.
Also, CNF dispersed in a hydrophilic liquid other than water may be used. The CNF dispersed in the plasticized starch material may be dispersed in one hydrophilic liquid or 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, formamide, and aqueous urea. The liquid may be one or a combination of two or more of the polyhydric alcohols mentioned above.

In the present invention, commercially available CNF may be used.
In the present invention, CNF can mean fibrous cellulose with an average fiber diameter of 10 nm to 3000 nm, which is hardly soluble in a solvent, unlike molecular cellulose. The average fiber diameter is more preferably 10 nm to 1000 nm, more preferably 10 nm to 500 nm, even more preferably 10 nm to 300 nm, and particularly preferably 10 nm to 100 nm. The aspect ratio of CNF can be, for example, 30-10,000, preferably 50-5,000, more preferably 50-1,000. The aspect ratio is a numerical value obtained by dividing the average fiber length by the average fiber diameter. The above average fiber length and average fiber diameter are average values of 10 arbitrary cellulose fibers observed with an electron microscope.

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

[Thermoplastic resin]

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

Polyolefin resins are polymers obtained by polymerization using olefins (eg, α-olefins) as main monomers. The polyolefin resin may be, for example, polyethylene (PE) or polypropylene (PP) or a combination thereof.
More specifically, polyethylene is low density polyethylene (LDPE), high density polyethylene (HDPE), very low density polyethylene (VLDPE), linear low density polyethylene ( LLDPE (Linear Low Density Polyethylene), or Ultra High Molecular Weight-Polyethylene (UHMW-PE).
The polypropylene may more specifically be a homopolymer polypropylene, or a random or block copolymer polypropylene, such as an ethylene-propylene copolymer.
The polyolefin-based resin may preferably be a biomass-derived polyolefin-based resin (eg, biomass-derived polyethylene, etc.), for example, biomass polyethylene. Biomass polyethylene can be, for example, LDPE, LLDPE, or HDPE. This makes it possible to reduce CO2 emissions.
The polyolefin resin may be a polyolefin resin produced using a metallocene catalyst. That is, the thermoplastic resin may be, for example, a metallocene-catalyzed polyethylene or polypropylene, or a combination thereof.
The polystyrene-based resin may also be a metallocene-catalyzed polystyrene-based resin.

Polyester-based resins are polymers in which monomers are polymerized through ester bonds. The polyester resin is, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polylactic acid (PLA), polycarbonate (PC), polybutylene adipate terephthalate (PBAT), polybutylene succinate. phosphate (PBS), polyhydroxyalkanoate (PHA), or a combination of two or more thereof.

The type of thermoplastic resin constituting the resin composition of the present invention may be appropriately selected by those skilled in the art, for example, according to the type of molded article formed from the resin composition. preferable. For example, when forming a film or sheet from the resin composition, the thermoplastic resin may be, for example, a polyolefin resin, preferably polyethylene or polypropylene, more preferably LLDPE or LDPE. Heating the resin composition of the present invention to the melting point of these resins is less likely to produce odor or coloration due to heating of the plasticized starch material. Therefore, it is possible to suppress the occurrence of odor or coloration when the resin composition is heated to produce a molded article.

The thermoplastic resin contained in the resin composition of the present invention preferably has a , particularly preferably those having a melting point of 95°C to 130°C. By employing a thermoplastic resin having a lower melting point, the temperature during molding can be lowered, and odor or coloration caused by heating of the plasticized starch material can be further suppressed.

The resin composition of the present invention contains a plasticized starch material and a thermoplastic resin in a ratio of, for example, 20 parts by weight:80 parts by weight to 80 parts by weight:20 parts by weight, preferably 30 parts by weight:70 parts by weight to 80 parts by weight. part: 20 parts by mass, more preferably 40 parts by mass: 60 parts by mass to 80 parts by mass: 20 parts by mass, still more preferably 50 parts by mass: 50 parts by mass to 80 parts by mass: 20 It can be contained in a ratio of 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 to the above numerical range, it is possible to produce molded articles having good quality from the resin composition. .

According to one embodiment of the 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.

[Other ingredients]

The resin composition of the present invention may contain other components in addition to the plasticized starch material and the thermoplastic resin. Examples of such other components include compatibilizers, oxidative decomposition accelerators, colorants, and antioxidants.

The compatibilizer may be used to further improve the compatibility between the plasticized starch material and the thermoplastic resin.
Examples of the compatibilizing agent include carboxylic anhydride-modified polyolefins, olefin-based graft-modified products, and olefin-based comonomers.
The carboxylic anhydride constituting the carboxylic anhydride-modified polyolefin may preferably be maleic anhydride. The compatibilizer may be, for example, one or a combination of two or more selected from the group consisting of maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer.
The olefin-based graft-modified product may be an acid-modified polyolefin, more specifically, a polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. The (unmodified) polyolefin used for graft modification may be, for example, polyethylene, polypropylene, or an ethylene/α-olefin copolymer (ethylene/propylene copolymer), particularly polypropylene. For example, acid-modified polyolefins described in JP-A-2010-095671 may be used.

The oxidative decomposition accelerator may be used to accelerate the decomposition of the thermoplastic resin. The oxidative decomposition accelerator can accelerate the oxidative decomposition of the thermoplastic resin and reduce the molecular weight of the thermoplastic resin to such an extent that microorganisms in soil or compost can biodegrade it.
The oxidative decomposition accelerator can include, for example, at least one compound selected from the group consisting of carboxylic acid metal salts, hydroxycarboxylic acids, transition metal compounds, rare earth compounds, and aromatic ketones. More preferably, the oxidative decomposition accelerator can be a combination of a carboxylate and a rare earth compound. Commercially available oxidative decomposition accelerators may be used, and examples thereof include P-Life (manufactured by P-Life Japan Inc.). The oxidative decomposition accelerator, particularly the combination of the carboxylate and the rare earth compound, is suitable for accelerating the decomposition of the polyolefin resin.
In one embodiment of the present invention, the thermoplastic resin contained in the resin composition may be a polyolefin resin (eg, polyethylene or polypropylene), and the resin composition may contain the oxidative decomposition accelerator. By adopting this embodiment, not only the plasticized starch material but also the thermoplastic resin is biodegraded. Therefore, the resin composition has a high degree of biomass and is more environmentally friendly.

The carboxylate contained in the oxidative decomposition accelerator may be, for example, a metal salt of an aliphatic carboxylic acid having 10 to 20 carbon atoms, more preferably a metal stearate. Examples of metal atoms that form metal salts with the aliphatic carboxylic acids include cobalt, cerium, iron, aluminum, antimony, barium, bismuth, chromium, copper, gallium, lanthanum, lithium, magnesium, molybdenum, nickel, calcium, and silver. , sodium, tin, tungsten, vanadium, yttrium, zinc, and zirconium, or a combination of two or more, more preferably calcium, magnesium, zinc, cobalt, cerium, iron, and copper. It may be one or a combination of two or more. For example, the metal salt may be iron stearate. As the carboxylate, one kind of carboxylate may be used alone, or a combination of two or more kinds of carboxylates may be used.

The rare earth compound contained in the oxidative decomposition accelerator is, for example, a rare earth oxide, a rare earth hydroxide, a rare earth sulfate, a rare earth nitrate, a rare earth acetate, a rare earth chloride, or a rare earth carboxylic acid. It may be an acid salt. More specifically, the rare earth compound includes cerium oxide, ceric sulfate, ceric ammonium sulfate, ceric ammonium nitrate, cerium acetate, lanthanum nitrate, cerium chloride, cerium nitrate, cerium hydroxide, and cerium octylate. , lanthanum oxide, yttrium oxide, and scandium oxide, or a combination of two or more thereof. As the rare earth compound, one kind of rare earth compound may be used alone, or a combination of two or more kinds of rare earth compounds may be used.

Titanium oxide and/or carbon black may be used as examples of the colorant. Moreover, as an example of the antioxidant, a phenol-based antioxidant may be used, but the present invention is not limited to this.

[Resin composition]
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 are described below.

According to one embodiment of the present invention, the thermoplastic resin composition may comprise the plasticized starch material, the thermoplastic resin, and the compatibilizer. The composition ratio of the plasticized starch material and the thermoplastic resin may be, as described above, for example, 20 parts by mass: 80 parts by mass to 80 parts by mass: 20 parts by mass, preferably 30 parts by mass: 70 parts by mass to It may be 80 parts by mass: 20 parts by mass, more preferably 50 parts by mass: 50 parts by mass to 80 parts by mass: 20 parts by mass. The compatibilizer may be, for example, 1 to 10 parts by weight, more preferably 2 to 9 parts by weight, with respect to 100 parts by weight 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 polyethylene, more preferably LLPDE. In this embodiment, the compatibilizer may be, for example, a carboxylic anhydride-modified polyolefin, preferably a maleic anhydride-modified polyethylene.
A thermoplastic resin composition according to this embodiment can be used to produce a film or sheet by a molding method such as, for example, inflation molding or T-die extrusion. The thickness of the film can be for example less than 200 μm, in particular greater than or equal to 10 μm and less than 200 μm. The thickness of the sheet can be, for example, ≧200 μm, in particular ≧200 μm and ≦1 mm.
In this embodiment, the thermoplastic resin may be, for example, a biomass-derived thermoplastic resin, in particular biomass-derived polyethylene.

According to another embodiment of the present invention, the thermoplastic resin composition may comprise the plasticized starch material, the thermoplastic resin, the compatibilizer, and the oxidative degradation accelerator. The composition ratio of the plasticized starch material and the thermoplastic resin may be, as described above, for example, 20 parts by mass: 80 parts by mass to 80 parts by mass: 20 parts by mass, preferably 30 parts by mass: 70 parts by mass to It may be 80 parts by mass: 20 parts by mass, more preferably 50 parts by mass: 50 parts by mass to 80 parts by mass: 20 parts by mass. The compatibilizer may be, for example, 1 to 10 parts by weight, more preferably 2 to 9 parts by weight, with respect to 100 parts by weight of the total amount of the plasticized starch material and the thermoplastic resin. The oxidative decomposition accelerator is, for example, 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the total amount of the plasticized starch material and the thermoplastic resin. More preferably, it may be 0.1 to 0.5 parts by mass.
In this embodiment, the thermoplastic resin may be, for example, a polyolefin resin, preferably polyethylene, more preferably LLPDE. In this embodiment, the compatibilizer may be, for example, a carboxylic anhydride-modified polyolefin, preferably a maleic anhydride-modified polyethylene. The oxidative decomposition accelerator can be a combination of a carboxylate and a rare earth compound.
A thermoplastic resin composition according to this embodiment can be used to produce a film or sheet by a molding method such as, for example, inflation molding or T-die extrusion. The thickness of the film can be for example less than 200 μm, in particular greater than or equal to 10 μm and less than 200 μm. The thickness of the sheet can be, for example, ≧200 μm, in particular ≧200 μm and ≦1 mm.
In this embodiment, the thermoplastic resin may be, for example, a biomass-derived thermoplastic resin, in particular biomass-derived polyethylene.
The thermoplastic resin composition according to this embodiment has a high degree of biomass, and the thermoplastic resin contained in the composition can be biodegraded.

The resin composition of the present invention may be used to produce molded articles other than films and sheets. Examples of other molded articles include, but are not limited to, containers (eg, bottle containers), bottle caps, plastic cardboard, non-woven fabrics, monofilaments, and the like. For example, the resin composition of the present invention may be used for blow molding, injection molding, profile extrusion, spinning (eg, melt spinning). Bottle containers, for example, can be molded by the blow molding. Bottle caps or containers, for example, can be produced by such injection molding. For example, a plastic cardboard can be molded by the profile extrusion molding. Such spinning (eg melt spinning) can form, for example, monofilaments.

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

[Film or sheet]

The invention also provides a film or sheet comprising a layer formed from the resin composition according to the invention. The film or sheet may be a single-layer film or sheet composed only of layers formed from the resin composition according to the present invention, or at least one layer formed from the resin composition according to the present invention. It may be a multilayer film or sheet laminated with at least one layer formed from another composition (particularly a resin composition). Said film may for example have a thickness of less than 200 μm, in particular a thickness of between 10 μm and less than 200 μm. Said sheet may for example have a thickness of ≧200 μm, in particular a thickness of ≧200 μm and ≦1 mm.

According to one embodiment of the present invention, the film or sheet has an average roughness (Ra) of 2 μm or less, more preferably 1.8 μm or less, and even more preferably 1.5 μm or less measured according to JIS B0031. on the surface, and the surface is the surface of the layer formed from the resin composition according to the present invention. The average roughness may be measured with a surface roughness meter according to JIS B0031. A film or sheet having such a smooth surface can be provided by the resin composition of the present invention.

The invention also provides porous films or sheets formed from the resin compositions of the invention. The porous film or sheet is preferably formed, for example, uniaxially or biaxially, by stretching the resin composition of the present invention that has been formed into the shape of a film or sheet (especially a single-layer film or sheet). can be produced by uniaxial stretching. The draw ratio can be, for example, 1.05 times to 5 times, preferably 1.05 times to 3.5 times. Such stretching can form holes in the film. Such stretching can lead to interfacial debonding, which can form pores. The porous film or sheet may be permeable to air but impermeable to water, for example as described below.

The present invention also provides a film or sheet formed from the resin composition of the present invention and which is permeable to air but impermeable to water. An air-permeable and water-impermeable film or sheet can be produced by subjecting the resin composition of the present invention, which has been molded into a single-layer film or sheet, to the stretching treatment described above. The air-permeable and water-impermeable film or sheet may be used, for example, as a backsheet for diapers (particularly paper diapers). In this specification, the backsheet of a diaper is positioned outside the absorbent material of the diaper (i.e., at a position farther from the body surface) so that liquids (such as urine) absorbed by the absorbent material are absorbed outside the diaper. means a tarp to prevent leakage into the air. The present invention also provides a diaper comprising the air permeable and water impermeable film or sheet as a backsheet.

In the present invention, whether a film or sheet is air permeable may be determined as follows. That is, the film or sheet has a water vapor permeability of, for example, 200 g/m ² ·day or more, preferably 250 g/m ² ·day or more, more preferably 300 g/m ² ·day or more, and even more preferably 350 g/m ² ·day or more. By having the degree, the film or sheet may be determined to be air permeable. Water vapor permeability is measured according to JIS Z 0208. If the film or sheet does not have the water vapor transmission rate, it may be determined not to be air permeable.

The water vapor transmission rate of the film or sheet before the stretching treatment is, for example, 50 g/m ² ·day or more and less than 200 g/m 2 ·day, particularly 70 g/m ^{2 ·} day or more and 150 g/m ² ·day or less. can be General polyethylene has a water vapor transmission rate of, for example, 5 to 15 g/m ² ·day. Therefore, films or sheets according to the present invention have a higher water vapor transmission rate than typical polyethylene, even before stretching.

In the present invention, whether a film or sheet is impermeable to water can be determined as follows. First, a film or sheet is placed on water-absorbing paper (for example, newspaper), room temperature water is placed on the film or sheet, and left for 10 minutes. After the standing, the film or sheet is moved so that the water does not drip from the film or sheet onto the paper. After the movement, if no trace of the absorption of water into the paper is visually confirmed, it may be determined that the paper is impermeable to water. If evidence of absorption of the water into the paper is visually observed after the transfer, it may be determined that the paper is not water impermeable.

2. plasticized starch material

The plasticized starch material of the present invention contains plasticized starch and a polar organic compound capable of gelatinizing or plasticizing starch, and the polar organic compound capable of gelatinizing or plasticizing starch gelatinizes starch at room temperature. The plasticized starch material contains at least a polar organic compound that can be gelatinized or plasticized, and the plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less.
All the explanations (such as composition and details of each component) regarding the plasticized starch material in the above "1. Resin composition" also apply to the plasticized starch material of the present invention. Therefore, the description of the plasticized starch material of the present invention is omitted.
The plasticized starch material has the same effect as described in "1. Resin composition" above. For example, the plasticized starch material can increase the biomass content of the resin composition and impart good quality to the resin composition.

3. Method for producing resin composition

The method for producing a resin composition according to the present invention includes a first mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch with 100 parts by mass of starch, The polar organic compound includes at least a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature, and heating the mixture obtained by the first mixing step to a temperature of 120°C to 150°C. A plasticizing step of plasticizing the starch to obtain a plasticized starch material, wherein the plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less. and a second mixing step of mixing the plasticized starch material and the thermoplastic resin in a ratio of 20 parts by weight:80 parts by weight to 80 parts by weight:20 parts by weight to obtain a resin composition.
By the production method of the present invention, the resin composition of the present invention described in the above "1. Resin composition" can be produced.

Each step of the manufacturing method will be described below.

(1) First mixing step

In the first mixing step, 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch is mixed with 100 parts by mass of starch. The starch and the polar organic compound capable of gelatinizing or plasticizing the starch are as explained in the above "1. Resin composition", and the explanation also applies to this production method. If the amount of the polar organic compound capable of gelatinizing or plasticizing starch is less than 20 parts by mass, it may not be possible to produce the plasticized starch material according to the present invention. Further, if the amount of the polar organic compound capable of gelatinizing or plasticizing starch is 100 parts by mass or more, the amount is excessive with respect to the amount of starch, and the can require extra effort and time.

The polar organic compound capable of gelatinizing or plasticizing the starch used in the first mixing step includes at least a polar organic compound capable of gelatinizing or plasticizing the starch at room temperature. The polar organic compound capable of gelatinizing or plasticizing starch at room temperature is preferably 0.1 parts by mass to 100 parts by mass, more preferably 0.5 parts by mass to 75 parts by mass, relative to 100 parts by mass of the starch. It is mixed with said starch in an amount of parts by weight, even more preferably from 1 part to 50 parts by weight. The polar organic compound capable of gelatinizing or plasticizing starch at room temperature is preferably one or a combination of two or more selected from formamide, N,N dimethylformamide and urea, more preferably formamide. The urea is mixed with starch, preferably as urea water (urea aqueous solution).

The polar organic compound capable of gelatinizing or plasticizing the starch used in the first mixing step may comprise a polar organic compound capable of gelatinizing or plasticizing the starch at elevated temperatures. That is, in one embodiment of the present invention, the polar organic compound capable of gelatinizing or plasticizing starch is a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at high temperature. It includes both possible polar organic compounds. The polar organic compound capable of gelatinizing or plasticizing starch at high temperatures may be one or more compounds selected from polyhydric alcohols. A combination of these compounds with the polar organic compound capable of gelatinizing or plasticizing the starch at normal temperature is particularly suitable for plasticizing the starch mixed in the resin composition. In the first mixing step, a polyhydric alcohol ester may also be mixed in addition to the starch and the polar organic compound.

In one embodiment of the present invention, in the first mixing step, a polyhydric alcohol is mixed in addition to starch and a polar organic compound capable of gelatinizing or plasticizing starch at room temperature. The polyhydric alcohol can be, for example, glycerin alone or a combination of glycerin and ethylene glycol.

In another embodiment of the present invention, in the first mixing step, a polyhydric alcohol and a polyhydric alcohol ester are mixed in addition to the starch and the polar organic compound capable of plasticizing the starch at ambient temperature. The polyhydric alcohol can be, for example, glycerin alone or a combination of glycerin and ethylene glycol. The polyhydric alcohol ester may be a monoglyceride.

Examples of the starch used in the first mixing step include underground starch and 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 modified starch (that is, modified starch).

The starch used in the first mixing step may preferably contain equilibrium moisture. The amount of equilibrium moisture is, for example, 10% to 15% by weight, preferably 10% to 14% by weight, more preferably 10% to 13% by weight, even more preferably 11% to 13% by weight, based on the starch weight. It can be mass %. It is preferred to use starch or modified starch with an equilibrium moisture content within the above numerical range for producing plasticized starch material according to the present invention. If starch without equilibrium moisture is used, the starch may not be plasticized.

The first mixing step may be performed using, for example, a stirrer. A commercially available device may be used as the stirrer. Said first pre-mixing step is preferably carried out at ambient temperature. By performing the first mixing step at room temperature and then performing the following plasticizing step, it is possible to suppress the generation of coloration and/or odor caused by heating starch.

The starch accounts for, for example, 40% to 85% by mass, preferably 45% to 80% by mass, more preferably 45% to 80% by mass, and more preferably It can account for 50% to 75% by weight.

In the first mixing step, the polar organic compound capable of gelatinizing or plasticizing the starch is, for example, an amount of 30 parts by mass to 120 parts by mass, preferably 35 parts by mass to 100 parts by mass with respect to 100 parts by mass of starch. amount, more preferably from 40 parts by weight to 100 parts by weight.

In the first mixing step, the polar organic compound capable of gelatinizing or plasticizing starch at room temperature is, for example, 1 part by mass to 60 parts by mass, more preferably 1 part by mass to 100 parts by mass of starch. It may be mixed in an amount of 50 parts by weight, even more preferably from 1 part to 40 parts by weight, particularly preferably from 1 part to 30 parts by weight.
The polar organic compound capable of gelatinizing or plasticizing starch at ambient temperature preferably comprises formamide, more preferably formamide alone.

Said 1st mixing process WHEREIN: The said polar organic compound which can gelatinize or plasticize starch may also contain the polar organic compound which can gelatinize or plasticize starch at high temperature. In the first mixing step, the polar organic compound capable of gelatinizing or plasticizing the starch at high temperature is, for example, the amount of the polar organic compound capable of gelatinizing or plasticizing the starch capable of plasticizing the starch at room temperature. The remaining amount less the amount of the polar organic compound may be mixed.
The polar organic compound capable of gelatinizing or plasticizing starch at elevated temperatures may preferably include glycerin and/or ethylene glycol. In said first mixing step, the ratio of weight of glycerin to weight of ethylene glycol is for example 5:1 to 0.5:1, preferably 4:1 to 1:1, more preferably 3:1 to 1:1, and glycerin and ethylene glycol may be used.
According to one embodiment of the present invention, the polar organic compound capable of gelatinizing or plasticizing starch at elevated temperatures may comprise only glycerin and ethylene glycol.
Monoglycerides may also be mixed with the starch in the first mixing step. In the first mixing step, the monoglyceride is, for example, 0 parts by mass to 5 parts by mass, preferably 0.1 parts by mass to 4 parts by mass, more preferably 0.5 parts by mass to 3 parts by mass with respect to 100 parts by mass of starch. can be mixed in part amounts.

(2) Plasticization process

The plasticizing step includes heating the mixture obtained in the first mixing step in an extruder. The heating plasticizes the starch to obtain a plasticized starch material. The heating is performed at a temperature of 120°C to 150°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 material extruded from the extruder can have, for example, a cylindrical or pellet shape.

The plasticized starch material is as described in the above "1. Resin composition", and the description also applies to the plasticized starch material in the present production method. For example, the plasticized starch material has a Type A durometer hardness of 20 or greater and a Type D durometer hardness of 40 or less.

(3) Second mixing step

In the second mixing step, the plasticized starch material produced in the starch material producing step and the thermoplastic resin are mixed in the above ratio. The mixing produces a resin composition according to the invention. The mixing may be performed, for example, using an extruder, preferably a twin-screw extruder. In the mixing step, a compatibilizer may be mixed in addition to the plasticized starch material and the thermoplastic resin. The compatibilizer is as described in the above "1. Resin composition", so description thereof is omitted.

In the mixing step, the ingredients to be mixed (eg, the plasticized starch material and the thermoplastic resin, and optionally the compatibilizer) are heated. The heating may be performed such 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 thermoplastic resin. For example, when the thermoplastic resin is polyethylene, the temperature can be, for example, 105°C to 120°C. For example, when the thermoplastic resin is polypropylene, the temperature can be, for example, 120°C to 170°C.

The manufacturing method may further include a molding step of molding the resin composition obtained in the mixing step. The molding process produces a molded article having a desired shape. The molding can be, for example, inflation molding or T-die molding. A resin composition molded into a film or sheet shape can be produced by such a molding technique. 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 can be, for example, 160°C to 185°C. For example, when the thermoplastic resin is polypropylene, the temperature can be, for example, 160.degree. C. to 185.degree.

The production method may further include a stretching step of stretching the resin composition molded into a film or sheet shape in the molding step. The stretching step can make the film- or sheet-shaped resin composition porous. The stretching conditions for making the film porous are the same as those described in the above "1. Resin composition", so the description thereof will be omitted.

4. Method for producing plasticized starch material

The present invention also provides a method of making the plasticized starch material. The production method is a mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch with 100 parts by mass of starch, wherein the polar organic compound is starch at room temperature. Plasticized starch by heating the mixture obtained by the mixing step and the mixture obtained by the mixing step to a temperature of 120 ° C. to 150 ° C. at least containing a polar organic compound capable of gelatinizing or plasticizing It includes a plasticizing process to obtain the material.
The production method produces the plasticized starch material used to produce the resin composition of the present invention.

The mixing step and the plasticizing step included in the manufacturing method are respectively the same as the first mixing step and the plasticizing step described in the above “3. Method for manufacturing a resin composition”. Therefore, the description of these steps in the above "3. Method for producing a resin composition" also applies to the above two steps of the method for producing a plasticized starch material of the present invention.

The present invention will be described in more detail below based on examples. It should be noted that the examples described below are examples of representative examples of the present invention, and the scope of the present invention is not limited only to these examples.

Test Example 1: Production and molding of resin composition (example using formamide)

(Example 1)

As shown in Table 1 below, 70 parts by mass of starch (Showa corn starch, Showa Sangyo Co., Ltd.), 32 parts by mass of glycerin, 16 parts by mass of ethylene glycol, and 4 parts by mass of formamide were prepared. These four ingredients were mixed in a mixer. The mixing was performed at ambient temperature. The glycerin, the ethylene glycol, and the formamide were pre-mixed before being charged to the mixer.
Table 2 below shows the parts by mass of other starch material-producing components when the amount of starch is 100 parts by mass.

The mixture obtained by the mixing was a powdery mixture. The powdery mixture was evaluated for stickiness according to the following criteria.
A: No stickiness and easy to handle.
B: Slightly sticky, but easy to handle.
C: Difficult to handle due to stickiness.

The evaluation results are shown in Table 1 below, and the mixture was non-sticky and easy to handle.

The mixture obtained by the mixing was fed into a single-screw extruder (VSK50, manufactured by Nakatani Kikai Co., Ltd.), and the mixture was kneaded. Ease of feeding the mixture from the feeder to the extruder was evaluated. Evaluation criteria are as follows.
A: It fell easily from the feeder into the extruder and was easy to feed.
B: It fell from the feeder into the extruder, but some adhered to the inner surface of the feeder.
C: It was difficult to drop from the feeder into the extruder.

The evaluation results are shown in Table 1 below, and the mixture easily fell from the feeder into the extruder and was easy to feed.

The cylinder temperature in the kneading process was 130°C. The vent was open during the kneading process. No suction was applied from the vent. After the kneading process, the mixture was extruded through the die of the extruder and an elongated, generally cylindrical plasticized starch material was obtained.

The physical properties, presence or absence of air bubbles, and stickiness of the plasticized starch material were evaluated according to the following criteria.
<Physical properties>
A: had a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less.
C: Had a type D durometer hardness greater than 40 or bubbling (swelling) throughout the plasticized starch material and hardness could not be measured.
<Presence or absence of air bubbles>
A: No bubbles were generated throughout the plasticized starch material.
B: Air bubbles were generated in a part of the plasticized starch material.
C: Air bubbles were generated throughout the plasticized starch material.
<Stickiness>
A: There was no stickiness.
B: Slightly sticky.
C: It was sticky.

The evaluation results are shown in Table 1 below and the plasticized starch material had a type A durometer hardness of 20. The plasticized starch material was elastic.
A photograph of the plasticized starch material is shown in FIG. 1(a). As shown in FIG. 1(a), no air bubbles were formed throughout the plasticized starch material.
Also, the plasticized starch material was non-greasy.

60 parts by mass of the plasticized starch material, 35 parts by mass of polyethylene (LLDPE, product name SP2540, Prime Polymer Co., Ltd.), and 5 parts by mass of a compatibilizing agent (maleic acid-modified polyethylene, manufactured by DuPont Co.) are extruded into a twin-screw extruder ( PCM30, Ikegai Co., Ltd.), and these components were subjected to a kneading process. The screw temperature in the kneading process was 120° C. and the resin pressure was 4.3 MPa. In the kneading process, suction from the vent was performed. A resin composition (hereinafter also referred to as "resin composition of Example 1") was obtained by the kneading treatment.

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 performed at 150°C to 160°C. A film having a thickness of 40 μm was obtained by the inflation molding.

The moldability in the inflation molding and the appearance of the resulting film were evaluated according to the following criteria.
<Moldability>
A: The resin composition stretched easily and was well blown up.
B: The resin composition was slightly difficult to spread, but it blew up.
C: The resin composition was torn before blowing up.
<Film Appearance>
A: The film had a smooth surface and no fish eyes or foreign matter was observed in the film.
B: Slight fish eyes or foreign matter was observed in the film.
C: Many fish eyes or foreign substances were observed.

The evaluation results are shown in Table 1 below, and the resin composition of Example 1 stretched easily and was well blown up. Also, the resulting film had a smooth surface and no fisheyes or foreign matter (such as starch particles) was observed in the film.

(Example 2)

As shown in Table 1 above, except that 70 parts by weight of starch, 16 parts by weight of glycerin, 8 parts by weight of ethylene glycol, 2 parts by weight of formamide, and 0.5 parts by weight of glycerin monostearate were mixed in the mixer. , in the same manner as in Example 1 to obtain a plasticized starch material. The glycerin, the ethylene glycol, the formamide, and the monoglyceride were mixed in advance before being put into the mixer.
A resin composition (also referred to as "resin composition of Example 2") was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 2, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 2, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the same evaluation results as in Example 1 were obtained.
More specifically, the plasticized starch material produced in Example 2 had a Type A durometer hardness of 65. The plasticized starch material was elastic. A photograph of the plasticized starch material is shown in FIG. 1(b). As shown in FIG. 1(b), no air bubbles were formed throughout the plasticized starch material. Also, the plasticized starch material was non-greasy.
The resin composition of Example 2 stretched easily and was well blown up. Also, the resulting film had a smooth surface and no fish eyes or foreign matter was observed in the film.

(Example 3)

As shown in Table 1 above, except that 70 parts by weight of starch, 16 parts by weight of glycerin, 8 parts by weight of ethylene glycol, 1 part by weight of formamide, and 0.5 parts by weight of monoglyceride were mixed in the mixer. A plasticized starch material was obtained in the same manner as in 1.
A resin composition (also referred to as "resin composition of Example 3") was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 3, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 3, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the same evaluation results as in Example 1 were obtained.

(Example 4)

As shown in Table 1 above, 70 parts by weight of starch, 16 parts by weight of glycerin, 8 parts by weight of ethylene glycol, 2 parts by weight of formamide, and 1 part by weight of monoglyceride were mixed in the mixer. A plasticized starch material was obtained in the same manner.
A resin composition (also referred to as "resin composition of Example 4") was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 4, inflation molding was performed in the same manner as in Example 1 to obtain a film.

Also in Example 4, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the same evaluation results as in Example 1 were obtained.

(Example 5)

As shown in Table 1 above, 70 parts by weight of starch, 16 parts by weight of glycerin, 8 parts by weight of ethylene glycol, 2 parts by weight of formamide, and 2 parts by weight of monoglyceride were mixed in the mixer. A plasticized starch material was obtained in the same manner.
A resin composition (also referred to as "resin composition of Example 5") was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 5, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 5, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the same evaluation results as in Example 1 were obtained.

(Example 6)

As shown in Table 1 above, a plasticized starch material was obtained in the same manner as in Example 1, except that 50 parts by weight of starch, 25 parts by weight of glycerin, and 25 parts by weight of formamide were mixed in the mixer. . The glycerin and the formamide were mixed in advance before being put into the mixer.
A resin composition (also referred to as "resin composition of Example 6") was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 6, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 6, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the same evaluation results as in Example 1 were obtained.

(Comparative example 1)

As shown in Table 1 above, in the same manner as in Example 1, except that 70 parts by weight of starch, 16 parts by weight of glycerin, 8 parts by weight of ethylene glycol, and 0.5 parts by weight of monoglyceride were mixed in the mixer. , attempted to obtain a plasticized starch material. However, no plasticized starch material was obtained as the material was sticky and did not fall into the extruder.
Also in Comparative Example 1, the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 1 above. As shown in Table 1, the mixture to obtain the starch material was sticky and difficult to handle. Also, the mixture was difficult to drop from the feeder into the extruder.

(Comparative example 2)

As shown in Table 1 above, except that 70 parts by weight of starch, 4 parts by weight of glycerin, 2 parts by weight of ethylene glycol, 0.5 parts by weight of formamide, and 0.5 parts by weight of monoglyceride were mixed in the mixer. A plasticized starch material was obtained in the same manner as in Example 1. The glycerin, the ethylene glycol, the formamide, and the monoglyceride were mixed in advance before being put into the mixer.

The mixture obtained by mixing with the mixer was a powdery mixture. The powdery mixture was non-sticky and easy to handle.
Also, the mixture was easily fed to the twin-screw extruder because the mixture was non-sticky.
However, the plasticized starch material produced in Comparative Example 2 had bubbles formed (expanded) throughout, as shown in FIG. 1(d). Therefore, the durometer hardness of both types A and E could not be measured.
The plasticized starch material could not be mixed with the thermoplastic resin because it was foamed and could not form uniform pellets.

(Comparative Example 3)
As shown in Table 1 above, except that 70 parts by weight of starch, 8 parts by weight of glycerin, 4 parts by weight of ethylene glycol, 1 part by weight of formamide, and 0.5 parts by weight of monoglyceride were mixed in the mixer. A plasticized starch material was obtained in the same manner as in 1. The glycerin, the ethylene glycol, the formamide, and the monoglyceride were mixed in advance before being put into the mixer.

The mixture obtained by mixing with the mixer was a powdery mixture. The powdery mixture was non-sticky and easy to handle.
Also, the mixture was easily fed to the twin-screw extruder because the mixture was non-sticky.
However, the plasticized starch material had a Type D durometer hardness of 50. Also, as shown in FIG. 1(c), air bubbles were formed in a portion of the plasticized starch material. The durometer hardness was measured for a portion where no air bubbles were formed. Also, the plasticized starch material was non-sticky.

A resin composition (also referred to as “resin composition of Comparative Example 3”) was obtained in the same manner as in Example 1 using the plasticized starch material.

Using the resin composition of Comparative Example 3, inflation molding was performed in the same manner as in Example 1 to try to obtain a film. However, the film formed from the resin composition was torn during inflation molding. Also, fish eyes or foreign substances were observed in the torn film.

(Summary of evaluation results)

As described above, in Examples 1 to 6 using formamide, the mixture obtained by mixing with a mixer was a powdery mixture, non-sticky and easy to handle. In addition, it was possible to easily supply these mixtures to the extruder.
Also, the plasticized starch materials produced in Examples 1-6 were easy to handle as they had no or little if any stickiness. None of the plasticized starch materials produced in Examples 1-6 had bubbles formed. Further, the moldability and appearance of the resin compositions of Examples 1 to 6 were also good.
From these results, it can be seen that the plasticized starch material according to the present invention can be produced more easily than the starch material that does not contain a polar organic compound capable of plasticizing starch at room temperature. Furthermore, the plasticized starch material according to the invention makes it possible to produce resin compositions with excellent moldability. In addition, the plasticized starch material can be formulated into a film or sheet by, for example, blown film molding, even when blended in high proportions relative to the thermoplastic resin. In addition, the films or sheets produced do not have fish eyes or inclusions due to starch.

Test Example 2: Evaluation of film surface

The surface and cross section of the film produced in Example 4 were observed with a scanning electron microscope. A photograph of the surface and cross section is shown in FIG. 2(a). As shown in FIG. 2(a), no starch particles were observed on the surface and cross section.
On the other hand, the surface and cross-section of a film made with non-plasticized starch material is shown in FIG. 2(b). The film was produced using an inflation molding machine (Placo Co., Ltd., die Φ65, extruder diameter 55 mm, temperature 160°C). The resin composition used to produce the film consisted of 30 parts by weight of non-plasticized starch, 5 parts by weight of metallic soap, 65 parts by weight of polyethylene, and 5 parts by weight of a compatibilizer. rice field. As shown in FIG. 2(b), the film containing the non-plasticized starch material has a large number of protrusions due to starch particles formed on the surface, and the starch particles can also be confirmed in the cross section.

The average roughness (Ra) of the two films was measured according to JIS B0031 using a surface roughness meter (handysurf E-40A surface roughness profiler, Tokyo Seimitsu Co., Ltd.). The measurement results are shown in FIG. As shown in FIG. 3, the average surface roughness of the film produced using the plasticized starch material in Example 4 was about 1.2 μm.
On the other hand, the average roughness of the film surface produced using the non-plasticized starch material was about 2.8 μm, measured by the same measurement method.

The maximum height (Ry) of the above two films was measured according to JIS B0061 using a surface roughness meter (handysurf E-40A surface roughness profiler, Tokyo Seimitsu Co., Ltd.). The measurement results are shown in FIG. As shown in FIG. 4, the maximum height of the film surface produced in Example 4 was about 8 μm.
On the other hand, the maximum height of the film surface produced with non-plasticized starch material was about 17 μm, measured by the same measurement method.

From the evaluation results of the film surface described above, it can be seen that the film formed from the resin composition containing the plasticized starch material according to the present invention has a smooth surface.

Test Example 3: Evaluation of physical properties of film

The tensile elongation and tensile strength of the film produced in Example 4 were measured according to JIS Z 1702. The same measurements were also made on films made with non-plasticized starch materials. The film was the same as that produced in Test Example 2. The results of these measurements of tensile elongation and tensile strength are shown in FIGS. 5 and 6, respectively.

As shown in Figure 5, the film made in Example 4 had a higher tensile elongation than the film made with the non-plasticized starch material. Therefore, it can be seen that the tensile elongation can be increased by plasticizing the starch in the resin composition. Also, as shown in FIG. 6, the tensile strength of both films was comparable.
In addition, a film having a tensile elongation equal to or higher than the horizontal line (150%) other than the scale shown in FIG. 5 and having a tensile strength equal to or higher than the horizontal line (11.8 MPa) other than the scale shown in FIG. satisfies the quality requirements of type 1 A (relatively flexible) specified in JIS Z 1702. As shown in Figures 5 and 6, the film produced in Example 4 meets these quality requirements and is therefore of good quality.

From the evaluation results of the film physical properties described above, it can be seen that the resin composition containing the plasticized starch material according to the present invention can produce a film having good quality.

Test Example 4: Preparation and evaluation of stretched film

The film produced in Example 4 was supplied to a uniaxial stretching apparatus (manufactured by Toray Engineering Co., Ltd.) to produce a uniaxially stretched film. The draw ratio was 2.5 times.

The water vapor permeability of the stretched film was measured according to JIS Z 0208 and found to be 370 g/m ² ·day. For example, polyethylene has a water vapor transmission rate of 5-15 g/m ² ·day. Therefore, it can be seen that the stretched film has a high water vapor transmission rate.

Test Example 5: Mixing Ratio of Polar Organic Compound and Starch

The state of the mixture was evaluated when the ingredients were mixed to make the plasticized starch material. The compositions of the mixtures evaluated are as shown in Table 3 below. From the viewpoint of ease of feeding to the extruder, the evaluation criteria were as follows. The evaluation results of the mixture are also shown in the same table.
A: Powdery.
B: Powdery but sticky with moisture.
C: Gel or liquid.

As shown in Table 3, the mixtures of Production Examples 2-1 and 2-2 were powdery but moist and sticky. Also, the mixtures of Production Examples 2-3 and 2-4 were gel or liquid. Therefore, a mixture obtained by mixing only glycerin with starch is not suitable for feeding to an extruder.
On the other hand, the mixtures of Production Examples 2-5 to 2-8 were powdery. In addition, the mixtures of Production Examples 2-5 to 2-8 were easily agglomerated by compression, and the agglomerates obtained by the compression were easily crushed and easily pulverized. Therefore, the mixture obtained by mixing only formamide with starch was suitable for feeding to the extruder.
The mixtures of Production Examples 2-9 to 2-12 were also powdery. In addition, the mixtures of Production Examples 2-9 to 2-12 easily solidified when compressed, and the lumps obtained by the compression were easily crushed and easily pulverized. Therefore, it can be seen that even when a mixture of glycerin and formamide is mixed with starch, a powdery mixture is obtained.
From the mixing ratio of the production example that was evaluated as A, by setting the amount of formamide to 10 parts by mass to 70 parts by mass with respect to 100 parts by mass of starch, it is considered that it is easy to obtain a mixture suitable for feeding to the extruder. .
Further, from a comparison of Production Examples 2-1 to 2-4 and Production Examples 2-9 and 2-12, it was found that when only glycerin was mixed with starch, a powdery mixture that was easy to handle was not obtained, but glycerin was mixed with formamide. It can be seen that the addition results in a powdery mixture that is easy to handle even though the amount of glycerin is the same and the formamide liquid is added.

Test Example 6: Production and molding of resin composition containing CNF

(Example 2-1)

In addition to 70 parts by mass of starch (Showa corn starch, Showa Sangyo Co., Ltd.), 32 parts by mass of glycerin, 16 parts by mass of ethylene glycol, and 4 parts by mass of formamide, 0.05 parts by mass of CNF was prepared, and these five components were A mixture was obtained by mixing in a mixer in the same manner as in Example 1. Using the mixture, kneading treatment was performed in the same manner as in Example 1 to produce a plasticized starch material containing CNF.
The plasticized starch material and polyethylene were kneaded by a twin-screw extruder to obtain a resin composition (referred to as the resin composition of Example 2-1). Using the resin composition, a film having a thickness of 40 μm (hereinafter referred to as “film of Example 2-1”) was obtained by inflation molding.

Using the resin composition of Example 1, a film having a thickness of 40 μm (hereinafter referred to as “film of Example 1”) was obtained by the molding method described above.

When the tensile strength and tensile elongation of the film of Example 2-1 and the film of Example 1 were measured, the former film had higher tensile strength and higher tensile elongation than the latter film. Therefore, it can be seen that the inclusion of CNF can improve the tensile strength and tensile elongation.
Also, although CNF is difficult to disperse in a thermoplastic resin such as polyethylene, CNF was well dispersed in the resin composition of Example 2-1. Therefore, it can also be seen that CNF can be well dispersed in the thermoplastic resin by mixing the plasticized starch material mixed with CNF with the thermoplastic resin.

(Example 2-2)

Three plasticized starch materials were produced in the same manner as in Example 2-1, except that the amount of CNF was changed to 0.1 parts by mass, 0.5 parts by mass, or 1 part by mass. Then, three resin compositions were obtained by using each of the three plasticized starch materials in the same manner as in Example 2-1. Using each of the three resin compositions, three sheets were produced in the same manner as in Example 2-1. All three sheets obtained had higher tensile strength and tensile elongation than the sheet of Example 1. In addition, CNF was well dispersed in the three resin compositions.

Test Example 7: Production and molding of resin composition (example using urea water)

(Example 3-1)

As shown in Table 4 below, 50 parts by weight of starch, 20 parts by weight of glycerin, 20 parts by weight of urea water (urea aqueous solution with a urea concentration of 32.5% by weight based on the weight of the aqueous solution), and glycerin mono are mixed in the mixer. A plasticized starch material was obtained in the same manner as in Example 1, except that 0.5 parts by weight of stearate was mixed. Table 5 below shows the amounts of other components per 100 parts by mass of starch.
A resin composition (also referred to as “resin composition of Example 3-1”) was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 3-1, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 3-1, the same evaluation as in Example 1 was performed. Evaluation results are also shown in Table 4 below. As shown in Table 4, both the tackiness of the mixture to obtain the plasticized starch material and the ease of feeding from the feeder to the extruder were rated A. Both the durometer hardness and the presence or absence of air bubbles of the plasticized starch material produced in Example 3-1 were evaluated as A. The plasticized starch material had a type A durometer of 30. Both the moldability and film appearance of the resin composition of Example 3-1 were evaluated as A.

(Example 3-2)

As shown in Table 4, 50 parts by mass of starch, 15 parts by mass of glycerin, 15 parts by mass of urea water (urea aqueous solution with a urea concentration of 32.5% by mass based on the aqueous solution mass), and glycerin mono are mixed in the mixer. A plasticized starch material was obtained in the same manner as in Example 3-1, except that 0.5 parts by mass of stearate was mixed.
A resin composition (also referred to as “resin composition of Example 3-2”) was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 3-2, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 3-2, the same evaluation as in Example 1 was performed. The evaluation results are also shown in Table 4 above. As shown in Table 4, both the tackiness of the mixture to obtain the plasticized starch material and the ease of feeding from the feeder to the extruder were rated A. Also, the durometer hardness, the presence or absence of air bubbles, and the stickiness of the produced plasticized starch material were all evaluated as A. The plasticized starch material had a Type A durometer of 48. A photograph of the plasticized starch material is shown in FIG. 7(7-a). As shown in the photograph, no air bubbles were generated. In addition, both the moldability and film appearance of the resin composition of Example 3-2 were evaluated as A.

(Example 3-3)

As shown in Table 4, 70 parts by mass of starch, 32 parts by mass of glycerin, 16 parts by mass of ethylene glycol, 4 parts by mass of urea water (urea having a urea concentration of 32.5% by mass based on the mass of the aqueous solution) A plasticized starch material was obtained in the same manner as in Example 3-1, except that an aqueous solution) and 0.5 parts by mass of glycerin monostearate were mixed.
A resin composition (also referred to as “resin composition of Example 3-3”) was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 3-3, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Example 3-3, the same evaluation as in Example 1 was performed. The evaluation results are also shown in Table 4 above. As shown in Table 4, both the tackiness of the mixture to obtain the plasticized starch material and the ease of feeding from the feeder to the extruder were rated A. Also, the durometer hardness, the presence or absence of air bubbles, and the stickiness of the produced plasticized starch material were all evaluated as A. The Type A durometer hardness of the plasticized starch material was 30. In addition, both the moldability and film appearance of the resin composition of Example 3-3 were evaluated as A.

(Example 3-4)

As shown in Table 4, 70 parts by mass of starch, 16 parts by mass of glycerin, 8 parts by mass of ethylene glycol, 2 parts by mass of urea water (urea having a urea concentration of 32.5% by mass based on the mass of the aqueous solution) A plasticized starch material was obtained in the same manner as in Example 3-1, except that an aqueous solution) and 0.5 parts by mass of glycerin monostearate were mixed.
A resin composition (also referred to as “resin composition of Examples 3-4”) was obtained in the same manner as in Example 1 using the plasticized starch material.
Using the resin composition of Example 3-4, inflation molding was performed in the same manner as in Example 1 to obtain a film.

In Examples 3-4, the same evaluation as in Example 1 was performed. The evaluation results are also shown in Table 4 above. As shown in Table 4, both the tackiness of the mixture to obtain the plasticized starch material and the ease of feeding from the feeder to the extruder were rated A. Also, the durometer hardness, the presence or absence of air bubbles, and the stickiness of the produced plasticized starch material were all evaluated as A. The type D durometer hardness of the plasticized starch material was 30. A photograph of the plasticized starch material is shown in FIG. 7(7-b). As shown in the photograph, no air bubbles were generated. In addition, both the moldability and the film appearance of the resin composition of Examples 3-4 were evaluated as A.

(Comparative Example 3-1)

As shown in Table 4 above, 50 parts by mass of starch, 6 parts by mass of glycerin, 6 parts by mass of urea water (a urea solution with a urea concentration of 32.5% by mass based on the mass of the aqueous solution), and 0 monoglyceride were added to the mixer. A plasticized starch material was obtained in the same manner as in Example 1, except that 0.5 parts by weight was mixed.

The same evaluation as in Example 1 was also performed in Comparative Example 3-1. The evaluation results are also shown in Table 4 above. As shown in Table 4, both the tackiness of the mixture to obtain the plasticized starch material and the ease of feeding from the feeder to the extruder were rated A. In addition, the said mixture foamed. Also, the durometer hardness of the produced plasticized starch material was evaluated as C, and the presence or absence of air bubbles was evaluated as B. The stickiness of the plasticized starch material was rated A. The type D durometer hardness of the plasticized starch material was 55. A photograph of the plasticized starch material is shown in FIG. 7(7-c). Air bubbles were seen on the surface of the plasticized starch material as shown in the photograph. In addition, the moldability and film appearance of the resin composition of Comparative Example 3-1 were both evaluated as C.

(Comparative Example 3-2)

As shown in Table 4 above, 70 parts by mass of starch, 8 parts by mass of glycerin, 4 parts by mass of ethylene glycol, and 1 of urea water (a urea solution having a urea concentration of 32.5% by mass based on the mass of the aqueous solution) are mixed in the mixer. A plasticized starch material was obtained in the same manner as in Example 1, except that parts by mass and 0.5 parts by mass of monoglyceride were mixed.

The same evaluation as in Example 1 was also performed in Comparative Example 3-2. The evaluation results are also shown in Table 4 above. As shown in Table 4, both the tackiness of the mixture to obtain the plasticized starch material and the ease of feeding from the feeder to the extruder were rated A. In addition, the said mixture foamed. Also, the durometer hardness of the produced plasticized starch material was evaluated as C, and the presence or absence of air bubbles was evaluated as B. The stickiness of the plasticized starch material was rated A. The type D durometer hardness of the plasticized starch material was 60. In addition, the moldability and film appearance of the resin composition of Comparative Example 3-1 were both evaluated as C.

From the above results and the results of Test Example 1, even when urea water is used instead of formamide, the resin composition obtained has excellent moldability and a film excellent in appearance from the resin composition can be produced.

Test Example 8: Production and molding of resin composition (example using polypropylene)

(Example 4-1)

A plasticized starch material was obtained as described in Example 1. Using the plasticized starch material, the resin composition (" Also referred to as "resin composition of Example 4-1") was obtained.
Using the resin composition of Example 4-1, inflation molding was performed in the same manner as in Example 1 to obtain a film.

The evaluation described in Example 1 was performed on the resin composition of Example 4-1. As a result of the evaluation, the resin composition of Example 4-1 stretched easily and was well blown up. In addition, the resulting film had a smooth surface, and no fish eyes or foreign matter caused by starch was observed in the film.

From this result, even when polypropylene is used instead of polyethylene, the resulting resin composition has excellent moldability, and it can be seen that a film with excellent appearance can be produced from the resin composition.

Claims (14)

comprising a plasticized starch material and a thermoplastic resin;
the plasticized starch material comprises a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less ,
The thermoplastic resin is a polyolefin resin,
Resin composition. comprising a plasticized starch material and a thermoplastic resin;
the plasticized starch material comprises a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The plasticized starch material has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less,
The thermoplastic resin is a polyolefin-based resin, a polyester-based resin, or a mixture of these resins.
Resin composition. 3. The resin composition of claim 1 or 2, wherein the plasticized starch material has no foamed portions. The resin composition according to any one of claims 1 to 3 , wherein the plasticized starch is a plasticized starch or a plasticized modified starch. The resin composition according to any one of claims 1 to 4 , further comprising cellulose nanofibers. A film or sheet comprising a layer formed from the resin composition according to any one of claims 1 to 5 . A film having a layer formed from the resin composition according to any one of claims 1 to 5 on its surface and having an average roughness (Ra) of 2 μm or less measured according to JIS B0031, or sheet. A porous film or sheet formed from the resin composition according to any one of claims 1 to 5 . comprising a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less ;
A plasticized starch material used to produce a resin composition by mixing with a polyolefin resin . comprising a plasticized starch and a polar organic compound capable of gelatinizing or plasticizing the starch;
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch is at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature. including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
A type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less, and
Used to produce a resin composition by mixing with a polyolefin resin or polyester resin or a mixture of these resins
Plasticized starch material. A first mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch and having an SP value of 10 to 25 with respect to 100 parts by mass of starch, wherein the polar The first mixing step, wherein the organic compound includes at least a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature;
a plasticizing step of plasticizing the starch to obtain a plasticized starch material by heating the mixture obtained from the first mixing step to a temperature of 120° C. to 150° C., wherein the plasticized starch material is type A; the plasticizing step having a durometer hardness of 20 or more and a type D durometer hardness of 40 or less; and a second mixing step of mixing the plasticized starch material and the thermoplastic resin to obtain a resin composition. ,
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The thermoplastic resin is a polyolefin resin,
A method for producing a resin composition. A first mixing step of mixing 20 to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch and having an SP value of 10 to 25 with respect to 100 parts by mass of starch, wherein the polar The first mixing step, wherein the organic compound includes at least a polar organic compound capable of gelatinizing or plasticizing starch at normal temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature;
a plasticizing step of plasticizing the starch to obtain a plasticized starch material by heating the mixture obtained from the first mixing step to a temperature of 120° C. to 150° C., wherein the plasticized starch material is type A; the plasticizing step having a durometer hardness of 20 or more and a type D durometer hardness of 40 or less;
A second mixing step of mixing the plasticized starch material and the thermoplastic resin to obtain a resin composition
including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
The thermoplastic resin is a polyolefin-based resin, a polyester-based resin, or a mixture of these resins.
A method for producing a resin composition. A mixing step of mixing 100 parts by mass of starch with 20 parts by mass to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch and having an SP value of 10 to 25 , wherein the polar organic compound contains at least a polar organic compound capable of gelatinizing or plasticizing starch at room temperature and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature , and the mixing step obtained by the mixing step a plasticizing step of plasticizing the starch by heating the mixture to a temperature of 120° C. to 150° C. to obtain a plasticized starch material;
including
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature includes a compound having at least one amide group,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
A method for producing a plasticized starch material having a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less and used for producing a resin composition by mixing with a polyolefin resin . A mixing step of mixing 20 parts by mass to 100 parts by mass of a polar organic compound capable of gelatinizing or plasticizing starch with 100 parts by mass of starch, wherein the polar organic compound gelatinizes or plasticizes starch at room temperature. the mixing step comprising at least a polar organic compound capable of gelatinizing starch and a polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than room temperature; and
a plasticizing step of heating the mixture obtained in the mixing step to a temperature of 120° C. to 150° C. to plasticize the starch to obtain a plasticized starch material;
including
The polar organic compound capable of gelatinizing or plasticizing starch is a compound having an SP value of 10 to 25,
The polar organic compound capable of gelatinizing or plasticizing starch at room temperature contains at least formamide,
The polar organic compound capable of gelatinizing or plasticizing starch at a temperature higher than normal temperature contains a polyhydric alcohol having 2 to 5 carbon atoms,
A plasticizer that has a type A durometer hardness of 20 or more and a type D durometer hardness of 40 or less and is used to produce a resin composition by mixing with a polyolefin resin or polyester resin or a mixture of these resins A method for producing a modified starch material.

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