JP2021152130A - Molded sheet of heat-plasticized starch/olefin resin composition and method for producing the same - Google Patents

Abstract

To provide a molded sheet of an olefinic resin composition containing heat-plasticized starch, which resists coloring during sheet molding and has improved moldability and durability, and a method for producing the same.SOLUTION: An olefinic resin composition containing heat-plasticized starch and having a melt flow rate (MFR) value of 0.7-1.5 g/10 min is molded into a sheet, thereby providing a molded sheet.SELECTED DRAWING: None

Description

The present invention relates to a molded sheet of a thermoplastic starch / olefin resin composition and a method for producing the same. More specifically, the present invention relates to a molded sheet of a thermoplastic starch / olefin resin composition having no decrease in mechanical strength, excellent secondary processability such as vacuum forming, and suppressed coloring, and a method for producing the same. be.

From the viewpoint of reducing carbon dioxide emissions associated with global warming, the possibility of using reproducible plant-derived components such as cellulose and starch has been investigated in various technical fields. In the field of resin molding technology as well, it has long been practiced to blend plant-derived components as fillers in general-purpose thermoplastic resins such as polyolefins. However, there is a problem that the mechanical strength such as the impact strength of the thermoplastic resin is lowered by simply mixing the plant-derived components, and the resin may be colored or deteriorated by the heat during processing.

As one of the methods for improving the impact strength of a thermoplastic resin, a method using a polymer alloy using thermoplastic starch (TPS) has been proposed in recent years. As a means for improving the mechanical properties of a thermoplastic resin using TPS, Patent Document 1 describes a resin composition consisting of starch, a polyolefin-based resin, a polyhydric alcohol liquid at room temperature, a surfactant, and a compatibilizer. It is disclosed. It is described that the composition is processed by a known processing method to obtain a molded thermoplastic resin composition having good mechanical properties.

Further, Patent Document 2 describes that an olefin-based resin composition containing thermoplastic starch is processed into a sheet by a calendar molding method. The calendar molding method is a sheet molding method having a higher yield than the T-die molding method, and is often used for sheet production of soft polyvinyl chloride resin and the like. However, since the T-die molding method is generally used as the molding method for the olefin-based resin composition, there has been a demand for a thermoplastic starch-containing olefin-based resin composition that can be film-formed by the T-die molding method.

Japanese Unexamined Patent Publication No. 2016-210824 Japanese Unexamined Patent Publication No. 2019-210375

Under such circumstances, the problem to be solved by the present invention is an olefin system containing thermoplastic starch, in which coloring during sheet molding using the T-die molding method is suppressed and moldability and durability are improved. It is an object of the present invention to provide a molded sheet of a resin composition and a method for producing the same.

As a result of diligent studies in view of such circumstances, the present inventors have found that the olefin resin composition containing the thermoplastic starch has a melting flow rate in a specific range (hereinafter, "melt flow rate" or "MFR"). It is found that processing by the T-die molding method is possible when the value of) is obtained, and the present invention has been completed.

That is, the present invention comprises molding an olefin resin composition containing thermoplastic starch and having a melt flow rate (MFR) value of 0.7 to 1.5 g / 10 minutes into a sheet shape. It is a molded sheet.
Further, the present invention is a molded sheet obtained by extruding an olefin resin composition obtained by melt-kneading an olefin resin mixture containing starch, a polyhydric alcohol and an olefin resin, and the olefin resin composition. The molded sheet having a melt flow rate (MFR) value of 0.7 to 1.5 g / 10 min.
Further, the present invention is a molded product obtained by thermoforming the above-mentioned molded sheet.
Further, in the present invention, an olefin resin mixture containing starch, a polyhydric alcohol and an olefin resin is melt-kneaded to contain thermoplastic starch and a melt flow rate (MFR) value of 0.7 to 1.5. A method for producing a molded sheet, which comprises a step of forming an olefin resin composition of gram / 10 minutes, extruding the olefin resin composition, and molding the olefin resin composition into a sheet shape.

In one embodiment of the present invention, an olefin resin composition containing thermoplastic starch and having a melt flow rate (MFR) value of 0.7 to 1.5 g / 10 minutes is molded into a sheet shape. It is a molded sheet. The olefin resin composition used for the molded sheet of the embodiment is a mixture of thermoplastic starch (hereinafter, may be referred to as “TPS”) and an olefin resin. Starch is composed of amylopectin, which is a long-chain molecule having a molecular weight of tens of thousands, has an amorphous amylose, and has a semi-crystalline structure with many branches having a molecular weight of several hundred thousand and has a granular structure. Starch does not develop thermoplasticity up to the temperature leading to heat denaturation. By heating and kneading starch with a plasticizer, this granular structure is broken, the uniformity is increased and the crystallinity is lowered, and it is the thermoplastic starch that enables thermoplastic processing like a general-purpose thermoplastic resin (thermoplastic starch). TPS). A detailed method for producing TPS is described in, for example, Patent Document 1 and the like described above.

In the olefin resin composition used in one embodiment of the present invention, the content of TPS is 20 to 70% by weight, preferably 25 to 65% by weight, and more preferably 30 to 60% by weight. If this ratio is 70% by weight or more, the mechanical properties of the molded product of the olefin resin composition may be insufficient. As described above, TPS is a hydrophilic polymer composition containing a water-soluble plasticizer and is inferior in water resistance. This drawback can be overcome by blending with a highly hydrophobic polyolefin resin, but if it is blended in an olefin resin composition at a high blending ratio of 70% by weight or more, a problem may occur in the water resistance of the composition. be. On the other hand, if the blending ratio of TPS in the olefin resin composition is 20% by weight or less, the T-die moldability becomes insufficient. Not only does it cause a problem in moldability in T-die molding, but it is also not preferable from the viewpoint of utilizing plant-derived components. In T-die molding, there are various properties required for an olefin resin composition, such as fluidity in a molten state, swell, slipperiness in a solid state, and peelability. As in the embodiment, TPS can be blended with the polyolefin resin to perform T-die molding without any problem. The reason is not clear, but the flow suitable for T-die molding is achieved by highly blending the TPS melt with high polarity and high cohesion with the melt of polyolefin resin with strong hydrophobicity and low cohesion. It is presumed that the characteristics can be obtained.

The melt flow rate (MFR) of the olefin resin composition used in the embodiment is preferably 0.7 to 1.5 g / 10 minutes. If the MFR of the olefin resin composition is larger than 1.5 grams / 10 minutes, it may be difficult to form a film by the extrusion molding method. If the MFR of the olefin resin composition is less than 0.7 g / 10 minutes, the temperature of the resin composition may rise during extrusion molding, and the thermoplastic starch may return to starch. The MFR is a value measured at 190 ° C. and a load of 2.16 kg according to JIS K7210-1.

The olefin-based resin composition used in the embodiment contains a propylene-based resin and an ethylene-based resin. As the propylene resin, a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-α-olefin random copolymer, a propylene block copolymer obtained by copolymerizing propylene and then copolymerizing ethylene and propylene, etc. Can be mentioned. Examples of ethylene-based resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, and α-olefin resin containing α-olefin having 4 or more carbon atoms as a main component. Can be mentioned. The olefin-based resin composition used in the present embodiment can be obtained by appropriately mixing the propylene-based resin and the ethylene-based resin. The propylene-based resin and the ethylene-based resin will be described in detail later.

In addition, the olefin resin composition used in the embodiment may contain an organic lubricant, if necessary. As organic lubricants, hydrocarbon-based lubricants: paraffin wax, synthetic polyethylene, liquid paraffin, etc., higher alcohol-based fatty acids: stearic acid, benic acid, 12-hydroxystearic acid, stearyl alcohol, etc., amide-based fatty acids: stearic acid amide, oleic acid amide, etc. , Elcaic acid amide, methylene bisstearic acid amide, ethylene bistearic acid amide, etc., metal soap: calcium stearate, zinc stearate, magnesium stearate, etc., ester-based lubricants: glycerin monostearate, glycerin monooleate, butyl stearate, etc. Can be preferably used. The organic lubricant reduces the friction between the olefin resin composition and the processing machine, improves the fluidity and peelability of the olefin resin composition, and plays a role of improving the molding efficiency and the appearance of the molded product. The organic lubricant is preferably contained in an amount of 0.3 to 3% by weight based on the olefin resin composition.

Examples of the commercially available olefin resin composition used in the embodiment include NEOPLA S-SERIES manufactured by Shiraishi Biomass Co., Ltd., and a method for producing the same is described in Patent Document 1.

The molded sheet of the present embodiment refers to a sheet having a generally thin and wide shape, and includes a film, a foil, a film, and the like.

Another embodiment of the present invention is a molded sheet obtained by extruding an olefin resin composition obtained by melt-kneading an olefin resin mixture containing starch, a polyhydric alcohol and an olefin resin. Here, the melt flow rate (MFR) value of the olefin resin composition is 0.7 to 1.5 g / 10 minutes.

As the starch used in the embodiment, any commercially available starch can be used. The starch may be either naturally occurring starch or modified starch. Examples of naturally occurring starch include cornstarch, wheat starch, potato starch, sweet potato starch, and tapioca starch, but it is preferable to use cornstarch because of its high distribution volume and stable quality. Examples of the modified starch include acetylated starch, phosphorylated starch, oxidized starch, hydroxypropyl starch and the like, and among these, it is preferable to use phosphorylated starch having a phosphorus content of 0.5% or less.

When producing the TPS used in the embodiment, a polyhydric alcohol can be used as a plasticizer for starch. Preferably, a polyhydric alcohol that is liquid at room temperature (preferably having a melting point lower than 25 ° C. and a boiling point higher than 25 ° C.), which has a large plasticizing effect on starch, can be used. Examples of the polyhydric alcohol liquid at room temperature for producing TPS used in the embodiment include glycerin, diglycerin, polyglycerin, ethylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol (molecular weight 200, molecular weight 300, molecular weight 400, and so on. Molecular weight 600), 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol and the like can be mentioned. In particular, it is preferable to use glycerin. One kind of polyhydric alcohol can be used from these, and a plurality of kinds of polyhydric alcohols can be mixed and used. Further, if necessary, a polyhydric alcohol that is liquid at room temperature and a polyhydric alcohol that is solid at room temperature can be used in combination. Examples of the polyhydric alcohol solid at room temperature include glucose, fructose, sorbitol, sucrose, trehalose, maltose and the like, and sorbitol can be particularly preferably used.

In the embodiment, the blending ratio of starch and polyhydric alcohol is preferably such that the weight ratio of these components (starch / polyhydric alcohol) is 10/90 to 40/60. If the compounding ratio of the polyhydric alcohol is less than 10% by weight, the disintegration of the crystal granules at the time of TPS formation becomes insufficient, and the plasticization of the obtained TPS may also be insufficient. On the other hand, when the compounding ratio of the polyhydric alcohol is more than 40% by weight, the strength of the molded product of the olefin resin composition containing TPS may decrease or the surface may become sticky.

The olefin-based resin used in the embodiment is a resin composed of a homopolymer of one kind of olefin or a copolymer of two or more kinds of olefins. The olefin-based resin does not include a resin modified with an unsaturated carboxylic acid or an unsaturated carboxylic acid derivative. Examples of the olefin resin include a propylene resin and an ethylene resin. These polyolefin-based resins may be used alone or in combination of two or more. Preferably, a propylene-based resin and an ethylene-based resin are mixed and used.

The propylene-based resin used in the embodiment is obtained by homopolymerizing a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-α-olefin random copolymer, or propylene, and then copolymerizing ethylene and propylene. A propylene block copolymer and the like can be mentioned.

The melting point (Tm) of the propylene-based resin used in the embodiment is preferably 90 to 160 ° C. from the viewpoint of improving the appearance of the molded product and increasing the mechanical strength such as rigidity and impact strength. , More preferably 100 to 155 ° C, more preferably 105 to 155 ° C.
The melting point (Tm) is the peak temperature of the peak at which the amount of heat absorption is maximum in the melting endothermic curve measured according to the method described above.

The propylene-based resin used in the embodiment can be produced by a solution polymerization method, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method, or the like. Further, these polymerization methods may be used alone or in combination of two or more. Then, as a method for producing a propylene resin, for example, "New Polymer Production Process" (edited by Koji Saeki, Kogyo Chosakai (published in 1994)), JP-A-4-323207, and JP-A-61-287917. The described polymerization method can be mentioned.

As the propylene-based resin used in the embodiment, a commercially available resin can be used. Examples of commercially available propylene resins include Novatec PP manufactured by Japan Polypropylene Corporation, Wintech, Wellnex, Waymax, Prime Polypro manufactured by Prime Polymer Co., Ltd., and Noblen and Excellen manufactured by Sumitomo Chemical Co., Ltd. Be done.

As the ethylene-based resin used in the embodiment, for example, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, and α-olefin having 4 or more carbon atoms are the main components. Α-Olefin resin to be used. The melting point (Tm) of the ethylene resin used in the embodiment is preferably 60 to 160 ° C. from the viewpoint of improving the appearance of the molded product and increasing the mechanical strength such as rigidity and impact strength. , More preferably 70 to 150 ° C, still more preferably 80 to 140 ° C. The melting point (Tm) is the peak temperature of the peak at which the amount of heat absorption is maximum in the melting endothermic curve measured according to the method described above.

The ethylene resin used in the embodiment can be produced by the same method as the above-mentioned method for producing a propylene resin. As the ethylene resin used in the embodiment, a commercially available resin can be used. Commercially available ethylene resins include Japan Polyethylene Corporation, Novatec, Harmorex, Kernel, Prime Polymer Co., Ltd. Evolu, Evolu H, Hi-Zex, Ult-Zex, Sumitomo Chemical Co., Ltd. Excellen, Sumikasen. And so on.

The olefin-based resin used in the embodiment can be used by appropriately adjusting the blending ratio of the propylene-based resin and the ethylene-based resin according to the characteristics required for the secondary molded product.

In the embodiment, the starch, the polyhydric alcohol, and the olefin resin are mixed to obtain an olefin resin mixture. This olefin-based resin mixture is melt-kneaded and reacted with starch and a polyhydric alcohol for thermoplasticization (starch is converted to TPS) to obtain an olefin-based resin composition. Here, the olefin resin mixture may contain an organic lubricant. As organic lubricants, hydrocarbon-based lubricants: paraffin wax, synthetic polyethylene, liquid paraffin, etc., higher alcohol-based fatty acids: stearic acid, benic acid, 12-hydroxystearic acid, stearyl alcohol, etc., amide-based fatty acids: stearic acid amide, oleic acid amide, etc. , Elcaic acid amide, methylene bisstearic acid amide, ethylene bistearic acid amide, etc., metal soap: calcium stearate, zinc stearate, magnesium stearate, etc., ester-based lubricants: glycerin monostearate, glycerin monooleate, butyl stearate, etc. Can be preferably used. The organic lubricant may be contained in an amount of 0.3 to 3% by weight based on the olefin resin mixture. In addition, the olefin resin mixture may contain a polymerization initiator such as an organic peroxide. Organic peroxides as polymerization initiators include peroxyketals: 1,1-di (t-hexylperoxy) cyclohexene, 1,1-di (t-butylperoxy) cyclohexene, and other dialkyl peroxides: Dikmylperoxide, α, α'-di (t-butyloxy) diisopropylbenzene, etc. Peroxyesters: t-butylperoxybenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane Etc., Dialkyl peroxides: Dibenzoyl peroxide, dilauroyl peroxide and the like can be preferably used. The organic peroxide may be contained in an amount of 0.01 to 1.0% by weight based on the olefin resin mixture.

A surfactant can also be added to the olefin resin mixture for the purpose of reducing the interfacial tension between the olefin resin and the TPS produced from starch to improve the melt-kneadability. As the surfactant in the embodiment, any of anionic, cationic, amphoteric and nonionic surfactants can be used. From the viewpoint of improving the heat resistance of the olefin resin composition obtained from the olefin resin mixture, it is preferable to use an anionic, amphoteric or nonionic surfactant. In addition, a plurality of types of surfactants can be mixed and used. From the viewpoint of improving the compatibility between the olefin resin and TPS, it is particularly preferable to use a nonionic surfactant having an HLB value of 3 to 9.

The blending amount of the surfactant is 0.5 to 7% by weight, preferably 1.0 to 5% by weight, based on the olefin resin used in the embodiment. When the blending amount is less than 0.5% by weight, it is difficult to obtain the effect of improving the mechanical properties by improving the compatibility, and when it is 7% by weight or more, the strength of the molded product obtained from the produced olefin resin composition is obtained. May decrease or the surface may become sticky.

In addition to this, the olefin-based resin mixture includes known substances generally added to the olefin-based resin, for example, stabilizers such as antioxidants, heat-resistant stabilizers, neutralizers, and ultraviolet absorbers, and bubbles, depending on the purpose. Additives, flame retardants, flame retardants, dispersants, antistatic agents, lubricants, anti-blocking agents such as silica, colorants such as dyes and pigments, plasticizers, nucleating agents and crystallization accelerators. Can be done. These substances can be added to an olefin resin mixture and melt-kneaded to obtain an olefin resin composition containing these substances.

Further, the olefin resin mixture may contain plate-like or powder-granular inorganic compounds such as glass flakes, mica, glass powder, glass beads, talc, clay, alumina, carbon black and Walsnite, whiskers and the like. can. These substances can be added to an olefin resin mixture and melt-kneaded to obtain an olefin resin composition containing these substances.

Further, if necessary, one or more kinds of elastomers may be blended in the olefin resin mixture. Examples of the elastomer include ethylene / α-olefin random copolymers, ethylene / α-olefin / non-conjugated polyene random copolymers, hydrogenated block copolymers, other elastic polymers, and mixtures thereof. ..

The melt flow rate (MFR) value of the olefin resin composition obtained here is preferably 0.7 to 1.5 g / 10 minutes. If the MFR of the olefin resin composition is larger than 1.5 g / 10 minutes, it may be difficult to form a film by an extrusion molding method (particularly, a T-die molding method described later). Further, if the MFR of the olefin resin composition is smaller than 0.7 g / 10 minutes, the temperature of the resin composition may rise during the T-die molding process, and the thermoplastic starch may return to starch. .. The MFR is a value measured at 190 ° C. and a load of 2.16 kg according to JIS K7210-1. It is also possible to mix two or more of the obtained olefin resin compositions and adjust so as to have an MFR of 0.7 to 1.5 g / 10 min.

The obtained olefin resin composition can be extruded to obtain a molded sheet of the embodiment. Extrusion molding can be performed by extruding an olefin resin composition from dies having various shapes. In particular, it is preferable to use the T-die molding method of extruding from the T-die. The T-die molding method will be described later. The molded sheet of the embodiment obtained by T-die molding can be further stretched to obtain a stretched film.

The width of the molded sheet of the embodiment is preferably 200 to 2000 mm, more preferably 300 to 1500 mm, and particularly preferably 500 to 1300 mm from the viewpoint of sheet manufacturing efficiency and ease of secondary processing.

The thickness of the molded sheet of the embodiment is preferably 0.1 to 2.0 mm, more preferably 0.2 to 1.2 mm, and particularly preferably 0.2 to 1.2 mm, from the viewpoint of sheet manufacturing efficiency and ease of secondary processing. Is 0.4 to 1.0 mm.

Further, another embodiment of the present invention is a molded product obtained by thermoforming the molded sheet of the embodiment. Thermoforming refers to molding a molded sheet made of a softened olefin resin composition using a mold. Thermoforming can be performed by a general method such as a vacuum forming method or a compressed pneumatic molding method. Agriculture / horticulture such as food trays, cups, containers, blister packs, various covers, pipes, electronic parts, vehicle parts, automobile parts trays, electronic parts trays, seedling raising pots, seedling raising trays, etc. Examples include supplies, food packaging members, medical packaging members, beauty packaging members, and the like.

Further, in another embodiment of the present invention, an olefin resin mixture containing starch, a polyhydric alcohol and an olefin resin is melt-kneaded to contain thermoplastic starch and have a melt flow rate (MFR) value of 0. A method for producing a molded sheet, which comprises a step of forming an olefin resin composition weighing 7 to 1.5 grams / 10 minutes, extruding the olefin resin composition, and molding the olefin resin composition into a sheet shape. In the production method of the embodiment, first, starch, a polyhydric alcohol, an olefin resin, an organic lubricant, an organic peroxide, a surfactant, and other additives are mixed as necessary to prepare an olefin resin mixture. obtain. This olefin resin mixture is put into a Banbury mixer, a kneader, a Henschel mixer, a uniaxial or multiaxial screw extruder, and melt-kneaded at preferably 80 ° C. to 230 ° C., more preferably 100 ° C. to 200 ° C. By this step, the plasticizer enters the inside of the starch granules and breaks the regular structure to form a homogeneous and heat-flowing TPS, and the olefin resin and the TPS are melt-kneaded to form a homogeneous olefin resin composition. Will be done. The melt flow rate (MFR) value of this olefin resin composition is 0.7 to 1.5 g / 10 minutes. This olefin resin composition is extruded into a sheet shape. Extrusion molding can be performed by extruding an olefin resin composition from dies having various shapes. In particular, it is preferable to use the T-die molding method of extruding from the T-die. The T-die molding method is a method of extruding a molten olefin resin composition from a slit to form a thin film. In the olefin-based resin composition of the embodiment, since the temperature of the resin composition does not rise too much during molding by the T-die molding method, a molded sheet can be produced without the inconvenience of TPS returning to starch. Can be done.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples. The method for producing the evaluation sample used in the examples or comparative examples is shown below.

(1) TPS-blended olefin resin composition for evaluation A NEOPLA-S series olefin resin composition manufactured by Shiraishi Biomass Co., Ltd. was used. The resin compositions used were four types, NEOPLA-S-212, 211, 157, and 214, and their MFRs were as follows:
S-212: 1.0 g / 10 minutes S-221: 0.5 g / 10 minutes S-157: 0.3 g / 10 minutes S-214: 2.6 g / 10 minutes

Using these resin compositions, olefin-based resin compositions were prepared by blending as shown in Table 1.

(2) Example 1: T-die molding method of evaluation sample Using a T-die extrusion molding machine manufactured by Hitachi Zosen, an evaluation sheet sample was prepared under the following conditions:
Screw diameter: 120 mm
Screw type: Full flight Molding conditions Air knife method Cylinder set temperature: 170 ℃
1st roll set temperature: 45 ° C
Second roll set temperature: 30 ° C
Pick-up speed: 10m / min Sheet width: 800mm
Sheet thickness: 0.5 mm

The evaluation of each molded sheet was performed as follows.
(Evaluation 1) T-die film forming property When the above T-die molding method was performed, the resin composition flowed smoothly and a homogeneous molded sheet was completed, which was evaluated as "good". On the other hand, when the T-die molding method is performed, the resin composition foams or the molded sheet has many so-called rheumatisms, which is "defective", and the T-die molding method cannot properly form a film. It was evaluated as "no film formation".

(Evaluation 2) DuPont Impact Test The impact strength of the molded sheet was measured by a method according to JIS K 5600-5-3 (weight drop resistance test of the coating film).
Measuring equipment used: DuPont impact tester manufactured by Toyo Tester Kogyo Co., Ltd. Striker used: Tip R6.35 mm, φ12.7 mm
Cradle: φ44 mm
Measurement temperature: 23 ° C

(Evaluation 3) Secondary workability of molded sheet The sheet was molded under the following conditions and evaluated. Those in which no uneven thickness, twist, or tear of the sheet was observed were evaluated as "good", and those in which uneven thickness, twist, or tear of the sheet was observed were evaluated as "poor".
Molding conditions: The sheet was preheated at 250 ° C. for 30 seconds and then formed by vacuum forming.
Tray shape: A tray with four recesses of length 287 x width 91 mm and depth 50 mm within a length of 310 mm x width of 410 mm.

Molded sheets were prepared by the T-die molding method using resin compositions having various melt flow rates. When a resin composition having an inappropriate melt flow rate is used, there is a problem that the film forming property is difficult (Comparative Example 2) or the secondary processability of the molded sheet is difficult (Comparative Example 1). On the other hand, the resin composition having an appropriate melt flow rate was excellent in film forming property, and the strength and secondary processability of the obtained molded sheet were also high (Examples 1 and 2). It can be seen that it is important to use a resin composition having a suitable melt flow rate in producing a molded sheet.

Claims (10)

A molded sheet obtained by molding an olefin resin composition containing thermoplastic starch and having a melt flow rate (MFR) value of 0.7 to 1.5 g / 10 minutes into a sheet shape. The molded sheet according to claim 1, wherein the olefin-based resin composition contains a propylene-based resin and an ethylene-based resin. The molded sheet according to claim 1 or 2, wherein the olefin resin composition further contains an organic lubricant, and the organic lubricant is contained in an amount of 0.3 to 3% by weight based on the olefin resin composition. A molded sheet obtained by extrusion-molding an olefin-based resin composition obtained by melt-kneading an olefin-based resin mixture containing starch, a polyhydric alcohol, and an olefin-based resin.
The molded sheet having a melt flow rate (MFR) value of 0.7 to 1.5 g / 10 minutes for the olefin resin composition. The molded sheet according to claim 4, wherein the olefin resin mixture contains a propylene resin and an ethylene resin. The molded sheet according to claim 4 or 5, wherein the olefin-based resin mixture further contains an organic lubricant, and the organic lubricant is contained in an amount of 0.3 to 3% by weight based on the olefin-based resin mixture. The molded sheet according to any one of claims 4 to 6, wherein the olefin resin mixture further contains an organic peroxide. A molded product obtained by thermoforming the molded sheet according to any one of claims 1 to 7. An olefin resin mixture containing starch, polyhydric alcohol and olefin resin is melt-kneaded to contain thermoplastic starch and have a melt flow rate (MFR) value of 0.7-1.5 g / 10 min. Forming a certain olefin resin composition,
A method for producing a molded sheet, which comprises a step of extruding the olefin resin composition and molding it into a sheet shape. The method for producing a molded sheet according to claim 9, wherein the olefin resin mixture further contains an organic lubricant and / or an organic peroxide.