Thermoplastic starch composition containing halogenated metal salt, pellets, flakes, compounded body, resin molded article, method for producing thermoplastic starch composition, method for producing pellets or flakes, method for producing compounded body, and method for producing resin molded article

Abstract

The purpose of the present disclosure is to provide a thermoplastic starch composition that is rarely discolored and has fluidity.　The thermoplastic starch composition according to the present disclosure comprises starch, a plasticizer for starch, and a halogenated metal salt, and has a melt flow rate of 0.01 g / 10 min or more at a temperature of 160°C under a load of 5 kg as determined in accordance with JIS K7210.

Description

Thermoplastic starch composition containing metal halide salt, pellets, flakes, compound body, resin molding, method for producing thermoplastic starch composition, method for producing pellets or flakes, method for producing compound body, and method for producing resin molding

[0001] The present disclosure relates to thermoplastic starch compositions, pellets, flakes, compound bodies, resin molded products, methods for producing thermoplastic starch compositions, methods for producing pellets or flakes, methods for producing compound bodies, and methods for producing resin molded products.

[0002] Recently, from the viewpoints of utilizing renewable materials and reducing carbon dioxide emissions, i.e., carbon circulation, and protecting the global environment through the widespread use of biodegradable resins, there is a demand to switch from conventional petroleum-derived resins to biomass-derived resins. Against this background, Patent Documents 1 and 2 disclose methods of blending starch into resins.

[0003] JP 2011-026538 A JP 2011-522950 A

[0004] Here, as in Patent Document 1, when a starch plasticizer is used to plasticize starch, the compound body may become discolored. Furthermore, as in Patent Document 2, a composition obtained by simply mixing starch with a starch plasticizer may have significantly reduced fluidity. A composition with low fluidity is difficult to disperse in a thermoplastic resin, which may cause a decrease in the physical properties of the resin molded product. Resin molded products produced using such compounds or compositions have limited physical properties and quality, which inevitably limits their uses.

[0005] Therefore, an object of the present disclosure is to provide a thermoplastic starch composition, pellets, flakes, a compound body, a resin molded product, a method for producing a thermoplastic starch composition, a method for producing pellets or flakes, a method for producing a compound body, and a method for producing a resin molded product that are less colored and have fluidity.

[0006] In order to achieve the above object, one embodiment of the thermoplastic starch composition of the present disclosure comprises starch, a starch plasticizer, and a metal halide salt, and the thermoplastic starch composition has a melt flow rate of 0.01 g / 10 min or more at a temperature of 160°C under a load of 5 kg according to JIS K 7210.

[0007] One aspect of the thermoplastic starch composition of the present disclosure is a thermoplastic starch composition comprising: starch, a starch plasticizer, and a metal halide salt, wherein the thermoplastic starch composition formed into pellets has a whiteness change rate X of 40% or less, as calculated by the following formula (1): X={(A-B) / A}×100 (1) In formula (1), A is the whiteness (WB) of the thermoplastic starch composition after forming, as calculated in accordance with JIS Z8715, and B is the whiteness (WB) of the thermoplastic starch composition after forming, as calculated in accordance with JIS Z8715, and after heating the thermoplastic starch composition at 160°C for 30 minutes.

[0008] The pellets of the present disclosure comprise the thermoplastic starch composition of the present disclosure.

[0009] The flakes of the present disclosure comprise the thermoplastic starch composition of the present disclosure.

[0010] The compound body of the present disclosure comprises the thermoplastic starch composition of the present disclosure.

[0011] The molded resin article of the present disclosure comprises the thermoplastic starch composition of the present disclosure.

[0012] The method for producing the thermoplastic starch composition of the present disclosure includes a mixing step of mixing raw materials including the starch, the starch plasticizer, and the metal halide salt.

[0013] The method for producing pellets or flakes of the present disclosure includes a strand-forming step of extruding a thermoplastic starch composition to form strands, and a strand-cutting step of cutting the strands to form pellets or flakes, wherein the thermoplastic starch composition is the thermoplastic starch composition of the present disclosure.

[0014] The method for producing a compound body of the present disclosure includes a first kneading step of kneading a raw material containing pellets or flakes with a raw material containing a thermoplastic resin, wherein the pellets are the pellets of the present disclosure, and the flakes are the flakes of the present disclosure.

[0015] The method for producing a resin molded product according to the present disclosure includes a resin molding step of resin molding a raw material including a compound body to produce a resin molded product, wherein the compound body is the compound body according to the present disclosure.

[0016] According to the present disclosure, a thermoplastic starch composition or the like that is less colored and has fluidity can be obtained.

[0017] FIG. 1 shows photographs of the thermoplastic starch compositions of test plots A-2, X-1, and X-2 before and after heating.

[0018] Preferred embodiments for carrying out the present disclosure will be disclosed below. However, the following embodiments disclose typical embodiments of the present disclosure, and the scope of the present disclosure is not limited to these embodiments.

[0019] In the present disclosure, unless otherwise specified, "mass %" and "wt %" may be read interchangeably, and "parts by mass" and "parts by weight" may be read interchangeably.

[0020] In the present disclosure, unless otherwise specified, the term "strand" refers to a general term for a thermoplastic starch composition extruded from various extruders, and the shape, such as length, is not particularly limited. For example, the term "strand" includes any shape extruded from various extruders, such as a long string-like one or a short plate-like one.

[0021] <Thermoplastic Starch Composition> First, the thermoplastic starch composition of the present disclosure will be described.

[0022] [Melt Flow Rate (MFR)] In one embodiment of the present disclosure, the melt flow rate (MFR) of the thermoplastic starch composition at 160°C under a load of 5 kg according to JIS K 7210 is 0.01 g / 10 min or more. The lower limit of the MFR may be, for example, 0.05 g / 10 min or more, 0.1 g / 10 min or more, or 0.2 g / 10 min or more, and the upper limit may be, for example, 100 g / 10 min or less, 80 g / 10 min or less, or 65 g / 10 min or less. The MFR can be measured by the measurement method described in the Examples below. The MFR can be adjusted, for example, by adjusting the compounding ratios of the starch, compatibilizer, thermoplastic resin, starch plasticizer, or metal halide salt, or by adjusting production conditions such as the production temperature or kneading time during production, as described below.

[0023] When the thermoplastic starch composition of the present disclosure has an MFR of 0.01 g / 10 min or more, it is possible to obtain a thermoplastic starch composition exhibiting high fluidity. For example, the present disclosure is useful when a compound body having a high starch content and a high breaking elongation is desired. Note that when the starch content is increased, a compound body containing a thermoplastic starch composition with a low MFR tends to have a lower breaking elongation.

[0024] [Whiteness Change Rate] In one aspect of the present disclosure, the thermoplastic starch composition has a whiteness change rate X of 40% or less when molded into pellets, as calculated by the following formula (1). The whiteness change rate X may be, for example, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, or 10% or less, or 0% or more, 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more. X={(A-B) / A}×100 (1) In the formula (1), A is the whiteness (WB) of the molded thermoplastic starch composition calculated in accordance with JIS Z8715, and B is the whiteness (WB) of the molded thermoplastic starch composition after heating at 160°C for 30 minutes, as calculated in accordance with JIS Z8715.

[0025] In the present disclosure, the thermoplastic starch composition is defined as the thermoplastic starch composition not containing a metal halide salt, which will be described later. ａ and the whiteness change rate X of the thermoplastic starch composition in which a part of the starch plasticizer described below contained in the thermoplastic starch composition not containing a metal halide salt is replaced with a metal halide salt. ｂ , and the difference (X ａ -X ｂ ) may be, for example, 100 or less, 70 or less, or 50 or less, or 1 or more, 3 or more, or 5 or more. ａ and the whiteness change rate X ｂ can be calculated by the above formula (1).

[0026] When a thermoplastic starch composition having a high whiteness change rate is used to produce a compound body or a resin molded product, the whiteness (WB) of the compound body and the resin molded product is also reduced. That is, the produced compound body and the resin molded product are discolored. Therefore, it is preferable that the whiteness change rate X of the thermoplastic starch composition is as small as possible.

[0027] [Biomass Degree] The biomass degree Y of the thermoplastic starch composition of the present disclosure is calculated, for example, by the following formula (2). The biomass degree Y is, for example, 80% or more, preferably 90% or more, most preferably 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, and is less than 100%, preferably 99.9% or less, 99.8% or less, 99.7% or less, or 99.6% or less, and most preferably 99.5% or less. Y=(C / D)×100 (2) In the formula (2), C is the weight of the biomass-derived material contained in the thermoplastic starch composition, and D is the total weight of the thermoplastic starch composition.

[0028] [Starch] The starch is not particularly limited, and examples thereof include unmodified starches obtained from corn, potato, sweet potato, cassava, sago palm, rice, wheat, etc. Specifically, examples thereof include corn starch, waxy corn starch, high-amylose corn starch, potato starch, sweet potato starch, tapioca starch, sago starch, rice starch, wheat starch, etc. Further examples thereof include processed starches obtained by etherifying or esterifying unmodified starches, or by subjecting unmodified starches to crosslinking treatment, etc. One type of starch may be used alone, or two or more types may be used in combination.

[0029] The starch is preferably, for example, corn starch or tapioca starch, which is an unmodified starch, from the viewpoint of production costs, and more preferably corn starch. As described above, it is presumed that low-molecular-weight materials exhibit coloration and thermal decomposition upon heating due to an increase in the number of reducing ends, and in this respect, corn starch or tapioca starch, which is an unmodified starch, is also preferred. Overall, corn starch is most preferred.

[0030] The moisture content of the starch used in the present disclosure is not particularly limited, but is, for example, 5 to 25% by weight, more preferably 7 to 23% by weight, even more preferably 9 to 20% by weight, and most preferably 10 to 18% by weight.

[0031] The starch content is, for example, 55 wt % or more, more preferably 60 wt % or more, and even more preferably 65 wt % or more, based on 100 wt % of the total weight of all components other than water contained in the thermoplastic starch composition, in consideration of improving the biomass content. From the viewpoint of mixing with a thermoplastic resin to disperse the starch, the starch content is 85 wt % or less, more preferably 80 wt % or less, and most preferably 75 wt % or less, based on 100 wt % of the total weight of all components other than water contained in the thermoplastic starch composition, and the range is, for example, 55 to 85 wt %, more preferably 60 to 85 wt %, even more preferably 60 to 80 wt %, and most preferably 65 to 75 wt %. In the present disclosure, even when the starch content is as high as 55 wt % or more, the starch exhibits high fluidity as long as the MFR is 0.01 g / 10 min or more, thereby facilitating kneading with a thermoplastic resin, etc.

[0032] The starch may be, for example, non-oxidized starch. In the present disclosure, the term "non-oxidized starch" refers to starch that is not oxidized starch, unless otherwise specified. The term "oxidized starch" refers to starch that is not oxidized starch, for example, starch in which aldehyde reducing groups, hydroxyl groups, glycol groups, etc. present in starch are oxidized to carboxyl groups or carbonyl groups by an oxidizing agent such as chlorine, bromine, hypochlorite, or hypobromite, or which is hydrolyzed in association with the oxidation reaction, thereby reducing the molecular weight of the starch. The term "oxidized starch" also includes starches that have been subjected to other chemical treatments, such as acetylated oxidized starch. As described in the Examples below, if the content of oxidized starch in the present disclosure is too high, the whiteness change rate of the thermoplastic starch composition tends to be high. Therefore, the content of the oxidized starch is preferably within the range described below. On the other hand, for example, substantially unoxidized starch that has been subjected to the action of a very small amount of the oxidizing agent or the like is considered to be non-oxidized starch in the present disclosure if the whiteness change rate is low.

[0033] The thermoplastic starch composition of the present disclosure may or may not contain the oxidized starch as an optional component in addition to the non-oxidized starch. Examples of the oxidized starch include starch oxidized with an oxidizing agent, more specifically, starch oxidized with chlorine, starch oxidized with bromine, starch oxidized with hypochlorite, and starch oxidized with hypobromite. When the thermoplastic starch composition contains the oxidized starch, the content of the oxidized starch is preferably greater than 0 wt % and not more than 25 wt %, not more than 20 wt %, or not more than 10 wt %, based on 100 wt % of the total weight of all components other than water contained in the thermoplastic starch composition, from the viewpoints of reducing the production cost of the thermoplastic starch composition of the present disclosure and reducing the whiteness change rate.

[0034] The oxidized starch may become discolored or be easily thermally decomposable when heated due to an increase in the number of reducing ends and an increase in aldehyde groups resulting from the oxidation reaction, so the content is preferably set to the above-mentioned range.

[0035] [Metal Halide Salt] The metal halide salt used in the present disclosure may be, for example, a known metal halide salt. The metal halide salt may include, for example, at least one selected from the group consisting of metal chlorides, metal bromides, and metal iodides. The fluidity-imparting effect of a thermoplastic starch composition, as described below, depends, for example, on the amount of the metal halide salt contained in the thermoplastic starch composition. The greater the amount of the metal halide salt contained in the thermoplastic starch composition, the greater the fluidity-imparting effect. Therefore, the metal halide salt preferably includes at least one of a metal chloride salt and a metal bromide salt, which contains more molecules (i.e., has a smaller molar mass) at the same weight of the metal halide salt, and more preferably includes a metal chloride salt. The metal halide salt may be, for example, at least one selected from the group consisting of sodium chloride, magnesium chloride, calcium chloride, aluminum chloride, sodium bromide, magnesium bromide, calcium bromide, sodium iodide, magnesium iodide, and calcium iodide.

[0036] The form of the metal halide salt is not particularly limited, and may be, for example, a solid such as a powder, or a liquid such as an aqueous solution. From the viewpoint of dispersion in the starch raw material, the liquid form is preferred.

[0037] The content of the metal halide salt is, for example, 0.1 to 10 wt %, more preferably 0.2 to 8 wt %, even more preferably 0.25 to 7 wt %, and most preferably 0.3 to 5 wt %. The content of the metal halide salt is preferably 0.1 wt % or more from the viewpoint of increasing the starch content, and is preferably 10 wt % or less from the viewpoint of imparting an improving effect on coloring.

[0038] Here, thermoplastic starch compositions that do not contain the metal halide salt, such as those produced by mixing the starch with the starch plasticizer, especially those with a high starch content of 50% by weight or more, have low fluidity (MFR). This is thought to make them difficult to disperse when kneaded with the thermoplastic resin described below, resulting in a deterioration in the physical properties of the compound. Meanwhile, the inventors of the present disclosure have found that mixing a mixture containing the starch, the starch plasticizer, and the metal halide salt under heating significantly improves the fluidity of the thermoplastic starch composition. From this, it is thought that the metal halide salt imparts high fluidity to the thermoplastic starch composition by plasticizing the starch or changing its structure. However, this is merely a hypothesis, and the present disclosure is not limited thereto.

[0039] [Starch Plasticizer] In the present disclosure, unless otherwise specified, the term "starch plasticizer" refers to a plasticizer used to plasticize starch, and does not refer to a starch-free plasticizer commonly used by those skilled in the art to adjust the physical properties of thermoplastic resins.

[0040] The starch plasticizer is not particularly limited as long as it is a substance that substantially plasticizes the starch, excluding water, and examples thereof include polyhydric alcohols, sugars, ammonia, ureas, ionic liquids, etc. Examples of the polyhydric alcohols include glycerol (glycerin), ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nanonediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and diglycerol. Examples of the sugars include sorbitol, glucose, maltitol, mannitol, and erythritol. These may be used alone or in combination. These substances may be incorporated into the starch in advance, for example. Furthermore, when a thermoplastic resin described below is contained, these substances may be incorporated into the thermoplastic resin in advance. Furthermore, these substances may be incorporated at any timing during the preparation of the thermoplastic starch composition of the present disclosure.

[0041] The starch plasticizer used in the present disclosure is preferably glycerin, propylene glycol, or sorbitol, more preferably glycerin, from the viewpoint of the effect of plasticizing starch.

[0042] The content of the starch plasticizer is, for example, 5 to 40% by weight, more preferably 10 to 35% by weight, even more preferably 15 to 30% by weight, and most preferably 20 to 30% by weight, based on 100% by weight of the total weight of all components other than water contained in the thermoplastic starch composition.

[0043] It is preferable that the starch plasticizer is substantially free of water. In other words, it is preferable that the starch plasticizer is not primarily composed of water. This is because, for example, when water is used as the primary component of the starch plasticizer, foaming occurs due to water evaporation during the production of the thermoplastic starch composition or during the molding of the compound body described below. For example, when the thermoplastic starch composition is produced using an extruder, unintentional foaming of the thermoplastic starch composition at the extruder outlet may result in reduced productivity. Furthermore, during the typical production of the thermoplastic starch composition or during the molding of the compound body described below, high-temperature conditions of 100°C or higher and the removal of gas by vacuum degassing are involved, which increases the likelihood that plasticizers with low boiling points, such as water, will be discharged outside the system. As a result, the starch plasticizer component contained in the thermoplastic starch composition before strand formation may decrease in volume compared to before the kneading, causing the thermoplasticity of the starch to be lost and significantly reducing the dispersibility of the starch in the thermoplastic starch composition.

[0044] [Thermoplastic Resin] The thermoplastic starch composition of the present disclosure may or may not further contain a thermoplastic resin. Furthermore, as described below, a compound can be obtained by kneading the thermoplastic starch composition of the present disclosure and the thermoplastic resin. The thermoplastic resin is not particularly limited, and for example, a commonly known thermoplastic resin can be used. Furthermore, for example, a biodegradable thermoplastic resin may be used. Examples of the thermoplastic resin include polyolefin-based resins, which are polymers of olefins having 2 to 20 carbon atoms, such as polypropylene, polybutene, polypentene, and polyethylene; polycyclic olefin-based resins such as polynorbornene; polystyrene-based resins such as polystyrene and ABS resin; and polyester-based resins such as polylactic acid, polyethylene terephthalate, polybutylene terephthalate, and polybutylene succinate, and mixtures thereof may also be used. Examples of the polyethylene include linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, and high-density polyethylene. The thermoplastic resin may also be a copolymer, such as an ethylene-propylene (block and random) copolymer, an ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, a propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, etc. One type of the thermoplastic resin may be used alone, or two or more types may be used in combination.

[0045] The thermoplastic resin is preferably, for example, polyethylene or polypropylene from the viewpoint of versatility, and more preferably polyethylene.

[0046] The melt flow rate of the thermoplastic resin may be, for example, from the viewpoint of production speed, 0.1 g / 10 min or more, 2 g / 10 min or more, or 5 g / 10 min or more, and 70 g / 10 min or less, 60 g / 10 min or less, or 40 g / 10 min or less, and the range is, for example, preferably 0.1 to 70 g / 10 min, 2 to 70 g / 10 min, or 5 to 60 g / 10 min, more preferably 5 to 40 g / 10 min. The melt flow rate may be determined, for example, by the method described in JIS K 7210 using a melt indexer, or may be data described in literature.

[0047] The content of the thermoplastic resin is not particularly limited, but is preferably high, e.g., 0% by weight, in consideration of improving the biomass content. Furthermore, when the thermoplastic resin is contained, the total weight of all components other than water contained in the thermoplastic starch composition is taken as 100% by weight, and the lower limit is, for example, more than 0% by weight, and the upper limit is 30% by weight or less, more preferably 20% by weight or less, even more preferably 10% by weight or less, and most preferably 5% by weight or less.

[0048] [Compatibilizer] The thermoplastic starch composition of the present disclosure may or may not further contain a compatibilizer. The compatibilizer is not particularly limited, and for example, a commonly known compatibilizer can be used. Examples include compounds containing one or more compounds selected from the group consisting of compounds having an acid anhydride group (e.g., maleic anhydride, succinic anhydride, glutaric anhydride), compounds having a carboxyl group (e.g., maleic acid, succinic acid, glutaric acid), compounds having an epoxy group, compounds having an imino group, compounds having an isocyanate group, compounds having an oxazoline group, and silane coupling agents having a reactive group (e.g., an alkoxy group). Acid anhydride groups, epoxy groups, imino groups, and isocyanate groups are functional groups that can react with hydroxy groups, and compounds having such functional groups are preferred as compatibilizers in the present disclosure. Examples of compounds that can be used as the compatibilizer include polymer compounds having the above-mentioned functional groups, such as polyolefin-based, acrylic-based, and styrene-based polymer compounds. From the viewpoint of ensuring affinity with the resin to be blended, polyolefin-based polymer compounds having the above-mentioned functional groups are preferred.

[0049] Examples of the polyolefin polymer compound include ethylene polymers [high-density polyethylene, medium-density polyethylene, low-density polyethylene, copolymers of ethylene and one or more other vinyl compounds (e.g., α-olefin, vinyl acetate, methacrylic acid, acrylic acid, etc.)], propylene polymers [polypropylene, copolymers of propylene and one or more other vinyl compounds, etc.], ethylene-propylene copolymers, polybutene, and poly-4-methylpentene-1, with propylene polymers being preferred. Specific examples of the polyolefin polymer compound having such functional groups include maleic anhydride-modified polyolefins, more specifically maleic anhydride-modified polypropylenes.

[0050] When the thermoplastic starch composition of the present disclosure contains a compatibilizer, the content of the compatibilizer is, for example, 0.1 to 10 wt%, where the total weight of all components other than water contained in the thermoplastic starch composition is 100 wt%. The content of the compatibilizer may have a lower limit of 0.1 wt% or more, 0.5 wt% or more, or 1 wt% or more, and an upper limit of 10 wt% or less, or 8 wt% or less, where the range is, for example, preferably 0.1 to 10 wt%, more preferably 0.1 to 8 wt%, even more preferably 0.5 to 8 wt%, and most preferably 1 to 8 wt%, where the total weight of all components other than water contained in the thermoplastic starch composition is 100 wt%.

[0051] [Other Additives] The thermoplastic starch composition of the present disclosure may or may not further contain various conventionally known additives. Examples of the additives include emulsifiers, elastomers, inorganic fillers, heat stabilizers, light stabilizers, UV absorbers, antistatic agents, etc. These may be used alone or in combination of two or more. Furthermore, these substances may be incorporated into the starch in advance. Furthermore, when a thermoplastic resin described below is contained, these substances may be incorporated into the thermoplastic resin in advance. Furthermore, these substances may be incorporated at any timing during the preparation of the thermoplastic starch composition of the present disclosure.

[0052] [Water contained in thermoplastic starch composition] As described above, it is preferable that the thermoplastic starch composition of the present disclosure is substantially free of water as the starch plasticizer. This is because, as described above, if water is substantially contained as the starch plasticizer, when the water-containing thermoplastic starch composition is kneaded (heated), the water contained as the starch plasticizer is likely to be discharged outside the system. As a result, the starch plasticizer component contained in the thermoplastic starch composition before forming into strands may decrease in weight compared to before the kneading, causing the thermoplasticity of the starch to be lost, and the dispersibility of the starch in the thermoplastic starch composition may be significantly reduced.

[0053] On the other hand, when the content of the starch plasticizer satisfies the above-mentioned numerical range (hereinafter, sometimes simply referred to as "when a sufficient amount of starch plasticizer is contained"), the thermoplastic starch composition of the present disclosure may contain a small amount of water. When the thermoplastic starch composition of the present disclosure contains a sufficient amount of starch plasticizer, it is preferable to contain a small amount of water (i.e., when the water content exceeds 0% by mass) because this facilitates the plasticization of the thermoplastic starch composition and makes it easier to optimize the production conditions of the thermoplastic starch composition. When the starch plasticizer is sufficiently contained, the water content of all raw materials constituting the thermoplastic starch composition of the present disclosure (hereinafter, sometimes simply referred to as the "total water content of raw materials") is, for example, greater than 0 wt% and not more than 30 wt%, preferably 5 to 30 wt%, more preferably 6 to 25 wt%, even more preferably 7 to 22 wt%, and most preferably 8 to 20 wt%, where the total weight of all components other than water contained in the thermoplastic starch composition is taken as 100 wt%, taking into consideration the dispersibility of the metal halide salt and the plasticity of the starch. The total water content of raw materials in the present disclosure may be calculated, for example, from the ratio of the weight of water added to the thermoplastic starch composition and the total water content of all components other than water contained in the thermoplastic starch composition to the total weight of the thermoplastic starch composition. Furthermore, the total water content of raw materials in the present disclosure may be calculated, for example, from the change in weight of the thermoplastic starch composition before and after drying using a dryer or the like, or may be measured using a device such as a moisture meter.

[0054] The thermoplastic starch composition provided in the present disclosure is not limited in its final form, and may be in the form of, for example, pellets or flakes, which will be described later, a compound obtained by further mixing the pellets or flakes with a thermoplastic resin, a resin molded product obtained by further mixing the compound with another thermoplastic resin, or a resin molded product, which will be described later, obtained by molding any of these.

[0055] <Pellets, flakes, compound body, and resin molded product> Next, the pellets, flakes, compound body, and resin molded product of the present disclosure will be described.

[0056] As described above, the pellets and flakes of the present disclosure comprise the thermoplastic starch composition of the present disclosure. In the present disclosure, the term "pellets" refers to, for example, the thermoplastic starch composition molded into a granular shape or the like, and more specifically, refers to a molded product obtained by cutting the thermoplastic starch composition in the form of strands. Furthermore, the term "pellet-like" refers to the shape or form of the product obtained when the thermoplastic starch composition in the form of strands is cut into granular shapes or the like. In the present disclosure, the term "flakes" refers to, for example, the thermoplastic starch composition molded into a plate, cube, rectangular parallelepiped, polygonal prism, polygonal pyramid, or the like, and more specifically, refers to the shape or form of the product obtained when the thermoplastic starch composition in the form of strands is cut. Furthermore, the term "flake-like" refers to the shape or form of the product obtained when the thermoplastic starch composition in the form of strands is cut into a plate, cube, rectangular parallelepiped, polygonal prism, polygonal pyramid, or the like.

[0057] As described above, the compound body of the present disclosure contains the thermoplastic starch composition of the present disclosure and another thermoplastic resin. The other thermoplastic resin is not particularly limited, and may be, for example, the same as the thermoplastic resin described above for the thermoplastic starch composition of the present disclosure. The compound body of the present disclosure may be extruded and then molded again into pellets, flakes, sheets, or the like. The compound body molded into pellets, flakes, or the like can be molded into a resin molded product, similar to the pellets and flakes of the present disclosure containing the thermoplastic starch composition of the present disclosure.

[0058] The breaking elongation change rate Z of the compound body of the present disclosure and the breaking elongation change rate Z of the compound body produced from the thermoplastic starch composition not containing the metal halide salt. ０ The difference between (Z ０ -Z) may have a lower limit of, for example, 3% or more, 5% or more, 8% or more, 9% or more, 10% or more, 15% or more, or 20% or more. Note that the larger the difference, the more improved the physical properties of the compound body. Therefore, the upper limit of the difference is not particularly limited. Note that the breaking elongation change rate Z and Z ０ is calculated by the following formulas (3-1) and (3-2): Z = {(C - D) / C} x 100 (3-1) Zｏ = {(C-D ｏ ) / C}×100 (3-2) In the formulas (3-1) and (3-2), C is the breaking elongation of the other thermoplastic resin before being blended into the thermoplastic starch composition, D is the breaking elongation of a compound body containing the thermoplastic starch composition containing the metal halide salt and the other thermoplastic resin, and D ０ is the breaking elongation of a compound body containing the thermoplastic starch composition not containing a metal halide salt and the other thermoplastic resin.

[0059] The breaking elongation can be measured by the method described in the examples below.

[0060] As described above, the molded resin product of the present disclosure includes the thermoplastic starch composition of the present disclosure. The molded resin product of the present disclosure may further include, for example, the compound body.

[0061] <Method for producing thermoplastic starch composition, method for producing pellets, flakes, etc., and method for producing compound body> Next, the method for producing the thermoplastic starch composition of the present disclosure, the method for producing pellets, flakes, etc., and the method for producing compound body will be described.

[0062] [Method for Producing Thermoplastic Starch Composition] As described above, the method for producing the thermoplastic starch composition of the present disclosure includes a mixing step of mixing raw materials containing the starch, the starch plasticizer, and the metal halide salt. The raw materials may also contain, for example, the other additives described above for the thermoplastic starch composition of the present disclosure.

[0063] The mixing step will be specifically described using an example. In the mixing step, for example, the starch, the starch plasticizer, and the metal halide salt are kneaded while being heated. By this kneading, the thermoplastic starch composition of the present disclosure is obtained. Examples of equipment for the kneading include a mill, a despa, a mixer kneader, a Banbury mixer, a roll, a single-screw or multi-screw extruder having two or more screws, a continuous kneader, and the like. Furthermore, a combination of these kneaders may be used, for example, a 1.5-screw extruder that combines a single-screw and a twin-screw extruder. In the present disclosure, there are no particular limitations, but for example, from the viewpoint of production speed, a multi-screw extruder or a combination thereof is preferred, and a twin-screw extruder is more preferred.

[0064] The pressure during the kneading is not particularly limited, but from the viewpoint of stable production, it is, for example, 0 MPa or more and 15 MPa or less, 10 MPa or less, 5 MPa or less, or 3 MPa or less, and the range is, for example, preferably 0 to 15 MPa, 0 to 10 MPa, or 0 to 5 MPa, and more preferably 0 to 3 MPa.

[0065] The temperature during the kneading is not particularly limited, but is, for example, 80°C or higher, 90°C or higher, or 100°C or higher from the viewpoint of sufficiently plasticizing the starch, and is 300°C or lower, 250°C or lower, or 200°C or lower from the viewpoint of preventing carbonization of the starch, and the range is, for example, 80 to 300°C, 90 to 250°C, or 100 to 200°C.

[0066] In the mixing step, the order of mixing is not particularly limited as long as the starch is plasticized and the thermoplastic starch composition of the present disclosure is obtained. For example, the starch, the starch plasticizer, and the metal halide salt may all be introduced into the kneading equipment at the same time, or the starch and the metal halide salt may be mixed first, and then the starch plasticizer may be added and introduced into the kneading equipment.

[0067] The method for mixing the metal halide salt with the starch is not particularly limited. For example, the metal halide salt may be mixed with the starch in advance, or may be mixed simultaneously with the starch plasticizer. The metal halide salt may also be added from a separate raw material inlet from the starch inlet using an extruder or the like. From the viewpoint of dispersibility in the raw materials contained in the thermoplastic starch composition, the metal halide salt is preferably mixed simultaneously with the starch plasticizer, and more preferably mixed in advance.

[0068] The metal halide salt may be mixed as a solid such as a powder, or as a liquid such as an aqueous solution, although mixing as a liquid is preferred from the viewpoint of dispersion.

[0069] [Method for producing pellets, flakes, etc.] After the kneading, for example, the thermoplastic starch composition discharged from a heated discharge port may be molded into an appropriate shape. The shape of the molded product is not particularly limited, and examples thereof include pellets, flakes, crumbs, powder, sheets, and chips. Alternatively, the kneaded product may be directly molded into a molded product. In this specification, molded products in the form of pellets, flakes, or sheets may be simply referred to as "pellets," "flakes," or "sheets."

[0070] When forming the starch into pellets or flakes, the pellets or flakes of the present disclosure can be produced, for example, as follows: As described above, the method for producing the pellets or flakes of the present disclosure includes a strand forming step of extruding the thermoplastic starch composition of the present disclosure to form strands, and a strand cutting step of cutting the strands to form pellets or flakes.

[0071] The strand formation step includes, for example, a step of extruding the thermoplastic starch composition mixed in the mixing step (extrusion step). The extrusion step can be performed using, for example, a conventionally known extruder. The extruder is not particularly limited, but for example, a twin-screw extruder can be used. Both the mixing step and the extrusion step may be performed using an extruder. The composition obtained in the mixing step may be recovered and supplied to the extruder in the extrusion step to form strands.

[0072] The strand cutting step is, for example, a step of cutting the thermoplastic starch composition in the form of strands discharged from an extrusion outlet in the extrusion step. Methods for converting the thermoplastic starch composition in the form of strands into pellets or flakes include, for example, a cold cut method in which the strands are air- or water-cooled and then cut with a strand cutter, a hot cut method in which the strands are cut with a rotary cutter attached to the outlet of the extruder, and an underwater cut method. From the viewpoint of quality stability, for example, the cold cut method and the hot cut method are preferred, and the cold cut method is more preferred.

[0073] [Method for Producing Compound Body] As described above, the method for producing a compound body of the present disclosure includes a first kneading step of kneading raw materials containing the pellets or flakes of the present disclosure with the thermoplastic resin. The raw materials may also contain, for example, other thermoplastic resins, the other additives, etc.

[0074] [Method for manufacturing a resin molded product] As described above, the method for manufacturing a resin molded product of the present disclosure includes a resin molding step of resin-molding a raw material containing the compound body of the present disclosure to manufacture a resin molded product. The resin molding step may include, for example, a second kneading step of kneading the compound body of the present disclosure with a raw material containing another thermoplastic resin, and a resin molding step of resin-molding the kneaded product obtained in the second kneading step to manufacture a resin molded product.

[0075] The resin molding step may be, for example, a step of resin molding the compound obtained in the first kneading step to produce a resin molded product. The resin molding step can be performed by, for example, a conventionally known method. Examples of the method include calendar molding, thermoforming, extrusion blow molding, inflation molding, vacuum molding, cast molding, foam molding, extrusion molding, injection molding, press molding, and melt spinning. Examples of molded products include containers, packaging materials, cushioning materials, daily necessities, machine parts, building materials, and automobile parts.

[0076] Next, examples of the present disclosure will be described, but the present disclosure is not limited to the following examples.

[0077] In this example and the above-described embodiment, the melt flow rate (MFR), water content, breaking elongation, and whiteness of the thermoplastic starch compositions were measured by the following procedures.

[0078] [Measurement of MFR] The MFR was measured in accordance with JIS K 7210 using a melt indexer (Toyo Seiki Co., Ltd., product name: G-02) at a temperature of 160°C and a load of 5 kg. The measurement sample was prepared by weighing 30 g of the thermoplastic starch composition in pellet form onto an aluminum tray, spreading the pellets so that they did not overlap, heating them at 160°C for 30 minutes, and then allowing them to cool at room temperature for 6 hours. The heat treatment was carried out using a shelf-type air-blowing dryer (Advantec Toyo Co., Ltd., product name: DRK632DC).

[0079] [Moisture Content] The moisture content of starch was measured by the dry weight method using a moisture meter (Brabender, trade name: MT-C) at 130° C. for 20 minutes.

[0080] The moisture content of the raw materials was calculated from the moisture contained in the starch, thermoplastic resin, elastomer, and other additives including the emulsifier used as the raw materials and the composition ratio (weight ratio) of each raw material. In this example, the moisture content of the raw materials was calculated using a moisture meter, but the moisture contents of the thermoplastic resin, elastomer, and other additives including the emulsifier may also be measured by the Karl Fischer method.

[0081] The total moisture content of the raw materials was calculated from the ratio of the sum of the weight of water added to the thermoplastic starch composition and the moisture content of the raw materials obtained by the above method to the total weight of the thermoplastic starch composition.

[0082] [Elongation at break] A compound obtained by the method described below was sandwiched between PET films and molded for 6 minutes at 150°C and 0.8 tonnes in a heat press (As One Corporation, product name: H300-1). The PET films were removed and cooled to room temperature to produce a film with a thickness of 0.1 to 1.5 mm. The obtained film was allowed to stand at 23°C and 50% RH for one week, and then molded into a dumbbell test piece (JIS K 7127 Type 5) using a lever-type sample cutter (Dumbbell Corporation, model number: SDL-100). In this example, the obtained film was left to stand at 23°C and 50% RH for one week, but the film was not limited thereto. For example, a film left to stand at 23°C and 50% RH for one day may also be used. The nine prepared dumbbell test pieces were measured for tensile elongation at break (breaking elongation) using a universal testing machine (A&D Co., Ltd., model number: RTG-1210) at a chuck distance of 70 mm and a pulling speed of 100 mm / min under an environment of 23°C and 50% RH. The breaking elongation was calculated as the average value of seven samples, excluding the maximum and minimum values ​​from the measurement results of the nine samples. Unless otherwise specified, the breaking elongation (% GL) defined in this specification is the result obtained by the above method. The results obtained by the above method are also defined as the characteristics of the thermoplastic starch compositions in this example.

[0083] In addition, the breaking elongation change rates Z and Z are calculated from the formulas (3-1) and (3-2) described in the embodiment. ０ The calculated breaking elongation change rates Z and Z ０ Therefore, the difference (Z ０ -Z) was calculated.

[0084] [Whiteness] The whiteness (WB) of the thermoplastic starch compositions obtained by the method described below or the compound bodies obtained by the method described below was analyzed in accordance with JIS Z8715 using a color difference meter (Nippon Denshoku Industries Co., Ltd., product name: SE7700). Unless otherwise specified, the whiteness (WB) defined in this specification is the result obtained by the above method, and the result obtained by the above method is defined as the characteristic of the thermoplastic starch composition in this example. The whiteness change rate was calculated using the formula (1) described in the embodiment. Heating at 160°C for 30 minutes was performed using a tray-type air-blowing dryer (Advantec Toyo Co., Ltd., product name: DRK632DC).

[0085] Based on the calculated whiteness change rate, the whiteness change rate of the comparative example (thermoplastic starch composition not containing a metal halide salt) was calculated as X ａ , the whiteness change rate of the example (the thermoplastic starch composition in which part of the starch plasticizer contained in the thermoplastic starch composition of the comparative example was replaced with a metal halide salt) is expressed as X ｂ The difference in the whiteness change rate (X ａ -X ｂ ) was calculated.

[0086] <Production of Thermoplastic Starch Composition> (Materials Used) In the present examples, the starches used were "unmodified cornstarch (Nihon Shokuhin Kako Co., Ltd., product name: Nisshoku Cornstarch Y (moisture content: 13.2%)")," "unmodified tapioca starch (Asia Modified Starch Co., Ltd., product name: TAPIOCA STARCH (moisture content: 13.2%)")," and "modified tapioca starch (Nihon Shokuhin Kako Co., Ltd., product name: Nisshoku Cleartext B-3 (moisture content: 12.3%)")." In addition, in this comparative example, the oxidized starch used was "oxidized starch (Nihon Shokuhin Kako Co., Ltd., product name: MS#3800 (moisture content: 13.9%)"." The starch content listed in the tables includes the moisture content of the starch. In addition, in the present examples, "cornstarch" may be simply referred to as "cornstarch."

[0087] Glycerin (Kanto Chemical Co., Ltd.) and sorbitol (Kanto Chemical Co., Ltd.) were used as starch plasticizers.

[0088] The metal halide salts used were magnesium chloride hexahydrate (Kanto Chemical Co., Ltd., special grade), calcium chloride (Kanto Chemical Co., Ltd., special grade), and magnesium bromide hexahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.).

[0089] [Example 1, Comparative Example 1] Pellets containing the thermoplastic starch compositions of this example and comparative example were prepared by the following procedure.

[0090] (Production of pellets containing thermoplastic starch composition) The raw materials listed in Table 1 below were premixed in a Kenwood mixer. The resulting mixture was supplied from a feeder installed at the top of C1 (the inlet of the kneader) of a twin-screw extruder (φ20 mm, L / D=45, Technovel Corporation). Note that, although pellets were produced using a twin-screw extruder in this example, the pellet production device is not limited to this. The kneading temperature was adjusted so that the outlet product temperature (the temperature of the thermoplastic starch composition at the outlet of the kneader) was 128°C, and the shaft rotation speed was set to 100 rpm. The discharged strand was air-cooled on a belt conveyor (Shinsei Sangyo Co., Ltd., Model: SMB-100) and supplied to the inlet of a pelletizer (Technovel Corporation, Product Name: SCP-203-2MT). The strands pulled by the pelletizer were cut in the pelletizer to produce pellets containing the thermoplastic starch compositions of Example 1 and Comparative Example 1 listed in Table 1 below (Test Areas A-1 to 10, 12 and X-1 to 7).

[0091] The pellets containing the thermoplastic starch composition of Test Plot A-11 were produced by the following method. In Test Plot A-11, metal halide salt-treated starch was used as the raw material. The metal halide salt-treated starch was prepared by first dissolving 1 wt % of the metal halide salt relative to the weight of the starch in 20 wt % of water relative to the weight of the starch. Next, the dissolved material was mixed with starch (unmodified cornstarch), dried at 130°C for 1 hour, and allowed to cool at room temperature to obtain a metal halide salt-treated starch. Thereafter, the obtained metal halide salt-treated starch and each raw material were pre-mixed without adding any additional metal halide salt so as to achieve the raw material composition and total raw material moisture content shown in Table 1, and the mixed mixture was supplied from a feeder installed at the top of C1 of the twin-screw extruder. After supplying from the feeder, the same operations as those for Test Plot A-1, etc. were performed to produce pellets containing the thermoplastic starch composition of Test Plot A-11.

[0092] In addition, for Test Plot A-13, pellets containing the thermoplastic starch composition of Test Plot A-13 were produced by the same operation as in Test Plot A-1, except that the kneading temperature was changed to that of Test Plot A-1 etc. and adjusted so that the outlet product temperature was 173°C.

[0093] For reference, photographs of the thermoplastic starch compositions of test plots A-2, X-1, and X-2 before and after heating are shown in FIG. 1.

[0094]

[0095]

[0096]

[0097] Example 2 and Comparative Example 2 Compound bodies of this example and comparative example were prepared according to the following procedure.

[0098] (Production of Compounds Containing Thermoplastic Starch Compositions) The thermoplastic starch compositions prepared in Example 1 and Comparative Example 1, a thermoplastic resin (LDPE, Tosoh Corporation, trade name: Petrothene (registered trademark) LDPE183, MFR 2 g / 10 min (according to JIS K 6922-1), elongation at break 400.3% GL), and a compatibilizer (Mitsui Chemicals, Inc., trade name: Admer HE-810) were placed in a polyethylene bag, the bag's opening was tied, and the mixture was thoroughly mixed by shaking up and down and left and right. The entire amount was supplied from a feeder installed at the top of C1 of a twin-screw extruder (φ20 mm, L / D=45, Technovel Co., Ltd.). The kneading temperature was adjusted so that the outlet product temperature was 159°C, and the shaft rotation speed was set to 150 rpm. The discharged strand compound was held by hand, water-cooled in a water tank (Technovel Co., Ltd., product name: SCB150-1500), and supplied to the inlet of a pelletizer (Technovel Co., Ltd., product name: SCP-203-2MT). The strand pulled by the pelletizer was cut inside the pelletizer to produce a pellet-shaped compound. The breaking elongation (% GL) and whiteness (WB) of the obtained compound were measured.

[0099]

[0100]

[0101]

[0102] Example 3, Comparative Example 3 In this example and comparative example, compound bodies were prepared using thermoplastic resins with different fluidities.

[0103] The compound bodies of Example 3 and Comparative Example 3 were produced in the same manner as in Example 2, except that the thermoplastic resin was changed to a thermoplastic resin with different fluidity as shown in Table 3 below (LDPE, Tosoh Corporation, trade name: Petrothene (registered trademark) LDPE212, MFR 13 g / 10 min (according to JIS K 6922-1), elongation at break 317.3% GL; LDPE, Tosoh Corporation, trade name: Petrothene (registered trademark) LDPE249, MFR 70 g / 10 min (according to JIS K 6922-1), elongation at break 287.5% GL).

[0104]

[0105]

[0106] Example 4, Comparative Example 4 In this example and comparative example, the type of thermoplastic resin was changed to polypropylene (PP) to prepare a compound body.

[0107] The compound bodies of Example 4 and Comparative Example 4 were produced in the same manner as in Example 2, except that the thermoplastic resin was changed to the thermoplastic resin shown in Table 4 below (PP, SunAllomer Co., Ltd., trade name: PF621S, MFR 6.5 g / 10 min (according to JIS K 6921-2), elongation at break 584.4% GL; PP, Japan Polypropylene Corporation, trade name: MG03BD, MFR 30 g / 10 min (according to JIS K 7210), elongation at break 165.3% GL), and the set temperature of each die of the twin-screw extruder was adjusted so that the outlet product temperature was 180°C.

[0108]

[0109] Example 5, Comparative Example 5 In this example and comparative example, compound bodies were produced by changing the type of thermoplastic resin.

[0110] Compound bodies of Example 5 and Comparative Example 5 were produced in the same manner as in Example 2, except that the thermoplastic resin was changed to the thermoplastic resin shown in Table 5 below (PBS, Mitsubishi Chemical Corporation, product name: FZ91, MFR 5 g / 10 min (according to ISO 1133), elongation at break 52.9% GL).

[0111]

[0112] Example 6, Comparative Example 6 In this example and comparative example, compound bodies were prepared by changing the blending ratio of thermoplastic resins.

[0113] Compound bodies of Example 6 and Comparative Example 6 were produced in the same manner as in Example 2, except that the blending ratios of the thermoplastic starch composition and the thermoplastic resin were changed as shown in Table 6 below.

[0114]

[0115] As shown in Table 1, all of the thermoplastic starch compositions of Example 1 containing a metal halide salt were found to have good fluidity. Furthermore, the rate of change in whiteness was also smaller than that of the thermoplastic starch composition of Comparative Example 1 containing no metal halide salt. In other words, it was confirmed that both fluidity and high whiteness were achieved (Test plots A-1 to A-13).

[0116] On the other hand, the thermoplastic starch composition of Comparative Example 1, which did not contain a metal halide salt, had a larger rate of change in whiteness than the thermoplastic starch composition of Example 1, which contained a metal halide salt. That is, it was more susceptible to discoloration by heating than Example 1 (Test Plots X-1 and X-2). Furthermore, Test Plots X-1 and X-3, which contained cornstarch, an unmodified starch, showed no fluidity at all, and MFR could not be measured. Furthermore, Test Plot X-2, which used oxidized starch whose molecular weight was reduced by oxidation treatment, had a high MFR, but a very high rate of change in whiteness of over 90%.

[0117] As shown in Table 2, the test plots of the Examples, in which glycerol or sorbitol was blended as a starch plasticizer, and LDPE183 was blended as a thermoplastic resin, showed higher whiteness than the Comparative Examples (test plots B1-1A to B1-5B). ０ That is, the changes in breaking elongation from the raw material LDPE183 were smaller in the Examples than in the Comparative Examples.

[0118] On the other hand, the test plots of the comparative examples all had lower whiteness than the test plots of the examples (test plots B1X-1A to B1X-2B). Furthermore, test plots B1X-2A and B1X-2B both showed low values ​​for the rate of change in breaking elongation comparable to those of the examples, but their whiteness (WB) was significantly low at 30 or less. This result suggests that the properties of the thermoplastic starch composition (X-2), which is the raw material for the compound, are significantly affected. The above-mentioned tendency was the same regardless of whether a compatibilizer was added or not.

[0119] As shown in Table 3, even when the thermoplastic resin was changed to another PE with different fluidity, the Examples (Test plots B2-1 to B2-5) were superior to the Comparative Examples (Test plots B2X-1 to B2X-6) in both whiteness (WB) and rate of change in elongation at break. Note that the Comparative Example (Test plot B2X-4) showed a lower rate of change in elongation at break than the Examples, but its whiteness (WB) was lower than the Examples.

[0120] As shown in Table 4, even when the thermoplastic resin was changed to PP, the examples (test plots B3-1 to B3-2) were superior to the comparative examples (test plots B3X-1 to B3X-4) in both whiteness (WB) and rate of change in elongation at break.

[0121] As shown in Table 5, even when the thermoplastic resin was changed to PBS, the example (test group B4-1) was superior to the comparative examples (test groups B4X-1 to B4X-2) in both whiteness (WB) and rate of change in elongation at break.

[0122] As shown in Table 6, even with a high blending amount of the thermoplastic starch composition, the Example (Test Plot B5-1) was superior in both whiteness (WB) and elongation at break to the Comparative Examples (Test Plots B5X-1 to B5X-2) which also had a high blending amount of the thermoplastic starch composition. Note that the Comparative Example (Test Plot B5X-2) showed a lower rate of change in elongation at break than the Examples, but its whiteness (WB) was lower than the Examples.

[0123] <Appendix> Some or all of the above embodiments and examples can be described as, but are not limited to, the following appendices. (Appendix 1) A thermoplastic starch composition comprising starch, a starch plasticizer, and a metal halide salt, wherein the thermoplastic starch composition has a melt flow rate of 0.01 g / 10 min or more at a temperature of 160°C and a load of 5 kg according to JIS K 7210. (Appendix 2) The thermoplastic starch composition according to Appendix 1, wherein the starch is a non-oxidized starch. (Appendix 3) The thermoplastic starch composition according to Appendix 1 or 2, wherein, when the total weight of all components contained in the thermoplastic starch composition other than water is 100 wt%, the starch content is 55 to 85 wt%, the starch plasticizer content is 10 to 40 wt%, and the metal halide salt content is 0.1 to 10 wt%. (Appendix 4) The thermoplastic starch composition according to any one of Appendices 1 to 3, wherein the thermoplastic starch composition formed into pellets has a whiteness change rate X of 40% or less, as calculated by the following formula (1): X = {(A - B) / A} x 100 (1) In formula (1), A is the whiteness (WB) of the thermoplastic starch composition after forming, as calculated in accordance with JIS Z8715, and B is the whiteness (WB) of the thermoplastic starch composition after forming, as calculated in accordance with JIS Z8715, after heating the thermoplastic starch composition at 160°C for 30 minutes. (Appendix 5) The thermoplastic starch composition according to any one of Appendices 1 to 4, wherein the starch plasticizer comprises at least one of a polyhydric alcohol and a sugar. (Appendix 6) The thermoplastic starch composition according to Appendices 5, wherein the polyhydric alcohol is at least one selected from the group consisting of glycerin, propylene glycol, and ethylene glycol, and the sugar is at least one of sorbitol and glucose. (Appendix 7) The thermoplastic starch composition according to any one of Appendices 1 to 6, which is substantially free of water as the starch plasticizer. (Appendix 8) The thermoplastic starch composition according to any one of Appendices 1 to 7, which contains at least one selected from the group consisting of metal chlorides, metal bromides, and metal iodides as the metal halide salt.(Appendix 9) The thermoplastic starch composition according to any one of Appendices 1 to 8, comprising a metal chloride salt as the metal halide salt. (Appendix 10) The thermoplastic starch composition according to any one of Appendices 1 to 8, wherein the metal halide salt is at least one selected from the group consisting of sodium chloride, magnesium chloride, calcium chloride, aluminum chloride, sodium bromide, magnesium bromide, calcium bromide, sodium iodide, magnesium iodide, and calcium iodide. (Appendix 11) A thermoplastic starch composition comprising starch, a starch plasticizer, and a metal halide salt, wherein the thermoplastic starch composition formed into pellets has a whiteness change rate X of 40% or less, as calculated by the following formula (1): X={(A−B) / A}×100 (1) In the formula (1), A is the whiteness (WB) of the thermoplastic starch composition after molding, calculated in accordance with JIS Z8715, and B is the whiteness (WB) of the thermoplastic starch composition after heating the thermoplastic starch composition after molding at 160°C for 30 minutes, calculated in accordance with JIS Z8715. (Appendix 12) Pellets comprising the thermoplastic starch composition according to any one of Appendices 1 to 11. (Appendix 13) Flakes comprising the thermoplastic starch composition according to any one of Appendices 1 to 11. (Appendix 14) A compound body comprising the thermoplastic starch composition according to any one of Appendices 1 to 11. (Appendix 15) A resin molded product comprising the thermoplastic starch composition according to any one of Appendices 1 to 11. (Appendix 16) A method for producing the thermoplastic starch composition according to any one of Appendices 1 to 11, comprising a mixing step of mixing raw materials containing the starch, the starch plasticizer, and the metal halide salt. (Appendix 17) A method for producing pellets or flakes, comprising a strand forming step of extruding a thermoplastic starch composition to form strands, and a strand cutting step of cutting the strands to form pellets or flakes, wherein the thermoplastic starch composition is the thermoplastic starch composition according to any one of Appendices 1 to 11.(Supplementary Note 18) A method for producing a compound body, comprising: a first kneading step of kneading a raw material containing pellets or flakes with a raw material containing a thermoplastic resin, wherein the pellets are the pellets described in Supplementary Note 12, and the flakes are the flakes described in Supplementary Note 13. (Supplementary Note 19) A method for producing a resin molded product, comprising: a resin molding step of resin molding a raw material containing the compound body to produce a resin molded product, wherein the compound body is the compound body described in Supplementary Note 14. (Supplementary Note 20) A method for producing a resin molded product according to Supplementary Note 19, comprising: a second kneading step of kneading the compound body with a raw material containing another thermoplastic resin, and a resin molding step of resin molding the kneaded product obtained in the second kneading step to produce a resin molded product.

[0124] This application claims priority based on Japanese Patent Application No. 2023-173164, filed October 4, 2023, the disclosure of which is incorporated herein in its entirety by reference.

[0125] As described above, the present disclosure can provide thermoplastic starch compositions, pellets, flakes, compound bodies, resin molded products, methods for producing thermoplastic starch compositions, methods for producing pellets or flakes, methods for producing compound bodies, and methods for producing resin molded products that are low in color and have fluidity. The present disclosure can provide, for example, thermoplastic starch compositions and masterbatches of thermoplastic starch compositions that are low in color and have fluidity. Furthermore, for example, by blending the thermoplastic starch composition of the present disclosure with a thermoplastic resin, compound bodies with a high starch content can be efficiently mass-produced. For example, by providing a thermoplastic starch composition with high fluidity, i.e., a high MFR, compound bodies can be provided that exhibit excellent physical properties different from those of blends with conventional thermoplastic starch compositions with low MFR, such as compound bodies exhibiting high elongation at break. The applications of the present disclosure are not particularly limited. For example, the applications of the thermoplastic starch compositions of the present disclosure are not limited to the pellets, flakes, and resin molded products of the present disclosure, and are arbitrary and can be used in a wide range of applications.

Claims

1. A thermoplastic starch composition comprising starch, a plasticizer for starch, and a metal halide salt, the thermoplastic starch composition having a melt flow rate of 0.01 g / 10 min or more at a temperature of 160° C. under a load of 5 kg according to JIS K 7210.

2. The thermoplastic starch composition of claim 1, wherein said starch is a non-oxidized starch.

3. The thermoplastic starch composition according to claim 1, wherein the total weight of all components other than water contained in said thermoplastic starch composition is taken as 100% by weight, the starch content is 55 to 85% by weight, the starch plasticizer content is 10 to 40% by weight, and the metal halide salt content is 0.1 to 10% by weight.

4. The thermoplastic starch composition according to claim 1, wherein the thermoplastic starch composition molded into pellets has a whiteness change rate X of 40% or less, calculated by the following formula (1): X={(A-B) / A}×100 (1) In the formula (1), A is the whiteness (WB) of the thermoplastic starch composition after molding, calculated in accordance with JIS Z8715, and B is the whiteness (WB) of the thermoplastic starch composition after heating the molded thermoplastic starch composition at 160° C. for 30 minutes, calculated in accordance with JIS Z8715.

5. The thermoplastic starch composition according to claim 1, wherein the starch plasticizer comprises at least one of a polyhydric alcohol and a sugar.

6. The thermoplastic starch composition according to claim 5, wherein the polyhydric alcohol is at least one selected from the group consisting of glycerin, propylene glycol, and ethylene glycol, and the saccharide is at least one of sorbitol and glucose.

7. The thermoplastic starch composition of claim 1, which is substantially free of water as a plasticizer for the starch.

8. The thermoplastic starch composition of claim 1, wherein the metal halide salt comprises at least one selected from the group consisting of metal chloride salts, metal bromide salts, and metal iodide salts.

9. The thermoplastic starch composition of claim 1, wherein said metal halide salt comprises a metal chloride salt.

10. The thermoplastic starch composition of claim 1, wherein the metal halide salt is at least one selected from the group consisting of sodium chloride, magnesium chloride, calcium chloride, aluminum chloride, sodium bromide, magnesium bromide, calcium bromide, sodium iodide, magnesium iodide, and calcium iodide.

11. A thermoplastic starch composition comprising starch, a starch plasticizer, and a metal halide salt, wherein the thermoplastic starch composition molded into pellets has a whiteness change rate X of 40% or less, as calculated by the following formula (1): X={(A-B) / A}×100 (1) In the formula (1), A is the whiteness (WB) of the thermoplastic starch composition after molding, as calculated in accordance with JIS Z8715, and B is the whiteness (WB) of the thermoplastic starch composition after heating the molded thermoplastic starch composition at 160°C for 30 minutes, as calculated in accordance with JIS Z8715.

12. A pellet comprising the thermoplastic starch composition of any one of claims 1 to 11.

13. A flake comprising the thermoplastic starch composition of any one of claims 1 to 11.

14. A compound body comprising the thermoplastic starch composition according to any one of claims 1 to 11.

15. A molded resin article comprising the thermoplastic starch composition according to any one of claims 1 to 11.

16. A method for producing the thermoplastic starch composition according to any one of claims 1 to 11, comprising a mixing step of mixing raw materials comprising the starch, the starch plasticizer, and the metal halide salt.

17. A method for producing pellets or flakes, comprising: a strand forming step of extruding a thermoplastic starch composition to form strands; and a strand cutting step of cutting the strands to form pellets or flakes, wherein the thermoplastic starch composition is a thermoplastic starch composition according to any one of claims 1 to 11.

18. A method for producing a compound body, comprising a first kneading step of kneading a raw material containing pellets or flakes with a raw material containing a thermoplastic resin, the pellets being the pellets described in claim 12, and the flakes being the flakes described in claim 13.

19. A method for producing a resin molded product, comprising: a resin molding step of resin molding a raw material containing a compound body to produce a resin molded product, wherein the compound body is the compound body according to claim 14.

20. A method for producing a resin molded product according to claim 19, comprising: a second kneading step of kneading the compound body with a raw material containing another thermoplastic resin; and a resin molding step of resin molding the kneaded product obtained in the second kneading step.

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