JP7359643B2 - Composite resin composition and its manufacturing method - Google Patents

Description

The present invention relates to a composite resin composition and a method for producing the same.

Due to concerns about global warming, ocean pollution from microplastics, and depletion of fossil fuels, the use of biomass as an alternative to petroleum-derived plastics is attracting attention. Among them, polyolefins are produced and used in large quantities, and have a large impact on the environment. Therefore, attempts are being made to replace part of the polyolefin with biomass. However, polyolefins and the biomass generally have poor affinity, and there is a problem that a homogenized mixture cannot be obtained.

In view of this problem, Patent Document 1 discloses a resin composition comprising a mixture of starch and a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof. Furthermore, Patent Document 2 discloses a resin composition comprising chemically modified starch, a plasticizer, urea, an emulsifier, and a linear polymer. Further, Patent Document 3 discloses a resin composition in which a compatibilizer acid-modified with an unsaturated dicarboxylic acid or the like is mixed with a polyolefin and a starch-based material.

Japanese Patent Application Publication No. 6-340771 Japanese Patent Application Publication No. 5-239265 Japanese Patent Application Publication No. 2004-2613

However, there is no study on the molecular weight of starch, and in Patent Document 1, it is necessary to improve the compatibility of starch by using a modified polyolefin obtained by chemically modifying polyolefin, and in Patent Document 2, it is necessary to improve the compatibility of starch with a linear polymer. In addition to starch and starch, it was necessary to use extra ingredients such as plasticizers and emulsifiers. Further, in Patent Document 3, it is necessary to improve the compatibility of starch by using a compatibilizer or the like in addition to the polyolefin and starch. As a result, for any of the above resin compositions, the manufacturing method becomes complicated, it is necessary to use chemicals and highly derivatize starch, and the resin used is a modified polyolefin or biodegradable resin. Limited to linear polymers.

An object of the present invention is to easily and inexpensively replace petroleum-derived components in a resin composition with biomass materials.

The present inventors conducted extensive studies in order to achieve the above object. As a result, surprisingly, by reducing the molecular weight of starch and adding urea, the dispersibility of starch was improved in a composite resin composition containing polyolefin, reduced molecular weight starch, and urea, and starch was The present inventors have discovered that a composite resin composition in which highly dispersed particles can be obtained, and have completed the present invention.

That is, the present invention includes acid-treated starch, alkali-treated starch, oxidized starch, enzyme-treated starch, starch mixed with metal salts, heat-treated starch, pulverized starch, extrusion-treated starch, gelatinized starch, Selected from the group consisting of radical treated starch, radiation treated starch, electron beam treated starch, microwave treated starch, ultrasonic treated starch, high frequency treated starch, pressure treated starch, milling treated starch, powder impact treated starch, and friction treated starch The present invention relates to a composite resin composition comprising at least one of :

In the composite resin composition of the present invention , the treated starch is preferably pregelatinized starch.

Particularly preferably, the treated starch has an RVA peak viscosity of 10% by mass size liquid that is 5% or less of the RVA peak viscosity of untreated starch as a raw material, and a difference between the maximum particle size and the minimum particle size of 2 μm or less. Some are more preferable.

In the composite resin composition of the present invention, it is preferable that the proportion of the polyolefin is 25 to 88 parts by mass, the treated starch is 10 to 50 parts by mass, and the urea is 2 to 30 parts by mass.

In the composite resin composition of the present invention, the polyolefin is desirably an unmodified polyolefin, which is inexpensive in terms of the cost of the composite resin composition.

In the method for producing a composite resin composition of the present invention, the polyolefin is mixed with acid-treated starch, alkali-treated starch, oxidized starch, enzyme-treated starch, metal salt, heat-treated starch, pulverized starch, extrusion-treated starch, etc. Starch, pregelatinized starch, radical treated starch, radiation treated starch, electron beam treated starch, microwave treated starch, ultrasonic treated starch, high frequency treated starch, pressure treated starch, milled starch, powder impact treated starch, and friction treated starch It is preferable to produce it by simultaneously charging at least one selected from the group consisting of treated starches and the above-mentioned urea into a kneading machine and kneading them.

As described above, according to the present invention, a composite resin composition in which petroleum-derived components in the resin composition are efficiently dispersed in a biomass material can be obtained simply and inexpensively.

It is an enlarged photograph of the composite resin composition in Test Example 11. It is an enlarged photograph of the composite resin composition in Test Example 17.

Other features and details of the invention will be described below.

Various polyolefins can be used in the present invention, such as homopolymers or copolymers of olefins such as ethylene, propylene, butene, hexene, 4-methyl-pentene, and octene; high-pressure low-density polyethylene; ; Linear low density polyethylene (LLDPE); High density polyethylene; Polypropylene; Random copolymer of propylene and an olefin having 2 or more and 10 or less carbon atoms. These polyolefins may be used alone or in combination of two or more.

The starch that can be used in the present invention is a low-molecular-weight starch. By using the low-molecular-weight starch, the starch is easily dispersed in the polyolefin, and the desired composite resin composition can be obtained.

In the composite resin composition of the present invention, the method for producing low molecular weight starch is not particularly limited. Starch processed by chemical treatment, heat treatment, radiation treatment, electron beam treatment, microwave treatment, ultrasonic treatment, high frequency treatment, pressure treatment, milling treatment, powder collision treatment, friction treatment, pulverization treatment, extrusion treatment, gelatinization treatment, etc. An example of this process is to physically reduce the molecular weight by applying energy to the substance. Among these, one or more of the following treatments can be performed easily and inexpensively: acid treatment, alkali treatment, oxidation treatment, enzyme treatment, mixing treatment with metal salts, heat treatment, pulverization treatment, extrusion treatment, and gelatinization treatment. Therefore, it is preferable that the starch has a reduced molecular weight. In particular, gelatinized starch is more preferred.

The decrease in the molecular weight of starch can be confirmed by known methods such as gel filtration chromatography and multi-angle light scattering, and can also be confirmed from the decrease in the viscosity of the starch after the molecular weight reduction treatment.

As the starch before the low molecular weight treatment, conventionally known starches can be used, such as unmodified starches such as corn starch, waxy corn starch, wheat starch, potato starch, tapioca starch, and sago starch, and esterified starches. Chemically modified starch that has undergone chemical modification such as processing, etherification treatment, and crosslinking treatment, and physical modified starch that has undergone physical treatment such as granulation treatment, moist heat treatment, hot water treatment, bleaching treatment, and sterilization treatment, or two or more of these treatments. Modified starch obtained by applying this method can be used.

As mentioned above, by incorporating urea into polyolefin and low-molecular-weight starch, the dispersibility of starch in polyolefin is improved, but one of the reasons for this is that urea breaks hydrogen bonds in starch. It is thought that this creates conditions in which starch can easily diffuse in polyolefin.

In addition, among the above-mentioned low-molecular-weight starch, the RVA peak viscosity of the 10% by mass paste is 5% or less of the RVA peak viscosity of the low-molecular-weight starch used as the raw material, and the difference between the maximum particle size and the minimum particle size is 2 μm. The following are more preferable. With such starch, as described above, the starch easily diffuses in the polyolefin, and a composite resin composition with less starch aggregates can be obtained.

This starch is also a type of low-molecular-weight starch, and can be obtained, for example, by adding a halogenated salt to starch and subjecting it to a heating process to make it low-molecular-weight.

The starch that is the raw material for the preparation of this low-molecular-weight starch can be the unprocessed starch described above, and it can also be chemically modified by chemical modification such as esterification, etherification, or crosslinking. Physical modification such as granulation treatment, moist heat treatment, hot water treatment, bleaching treatment, and sterilization treatment, or a combination of two or more of these treatments can be performed.

There are no particular restrictions on the type of halide salt used in the preparation of this low-molecular-weight starch, as long as it is industrially available, but examples include chloride salts (iron chloride (II, III), calcium chloride, Magnesium, ammonium chloride, lithium chloride, sodium chloride, etc.), bromide salts (iron (II, III) bromide, calcium bromide, magnesium bromide, ammonium bromide, lithium bromide, sodium bromide, etc.), iodide salts (iron(II) iodide, calcium iodide, magnesium iodide, ammonium iodide, lithium iodide, sodium iodide, etc.), etc. Chloride salts are preferable from the viewpoint of their effects, and calcium chloride, Ammonium chloride and magnesium chloride are more preferred, and calcium chloride is particularly preferred from the viewpoint of particle size distribution. A plurality of types of halogenated salts may be used in combination.

In the preparation of this low-molecular-weight starch, the heat denaturation conditions may be appropriately adjusted using the peak viscosity ratio and the difference between the maximum and minimum particle sizes as indicators, as described above. The addition rate of calcium chloride per 100 parts by mass is 0.8 to 15 parts by mass, and the heating process can be carried out at 50 to 200°C for 0.5 hours to 30 days, and when ammonium chloride is added, starch The addition rate of ammonium chloride per 100 parts by mass is 0.1 to 5 parts by mass, and the heating process can be carried out at 50 to 200°C for 0.5 hours to 30 days, and when magnesium chloride is added, starch The addition rate of magnesium chloride per 100 parts by mass is set at 0.1 to 8 parts by mass, and the low-molecular-weighting treatment can be carried out by heating at 50 to 200° C. for 0.5 hours to 30 days.

The low-molecular-weight starch can be subjected to washing and drying treatments as necessary.

In addition, the particle size distribution waveform of this low-molecular-weight starch can be obtained by, for example, preparing a dispersion liquid by dispersing a starch sample in water so that the solid content concentration is 0.02% by mass. It can be measured using a dynamic light scattering measuring instrument such as ELSZ-2000ZS manufactured by the company. The particle size distribution waveform is calculated from the scattering intensity distribution.

Furthermore, the RVA peak viscosity of this low-molecular-weight starch is measured as follows. Disperse a starch sample in water to a concentration of 10% by mass to prepare 30g of a dispersion liquid, hold it at 50°C for 1 minute while stirring with a paddle at a rotation speed of 160 rpm, and hold it at 50°C for 3 minutes and 42 seconds from 50°C. A continuous heating state is applied to reach 95°C, and the temperature is maintained at 95°C for 2 minutes and 30 seconds, a continuous cooling state is provided to reach 50°C for 3 minutes and 48 seconds, and the temperature is maintained at 50°C for 2 minutes. Under these conditions, the peak viscosity (highest viscosity) is measured. The peak viscosity can be measured using a rapid viscoanalyzer (RVA), and as the rapid viscoanalyzer (RVA), for example, one manufactured by Perten Instruments can be used.

Further, the maximum particle size and minimum particle size of this low-molecular-weight starch can be measured by the same method as that used to obtain the particle size distribution waveform described above.

In the present invention, it is preferable that the proportion of polyolefin is 25 to 88 parts by mass, the low molecular weight starch is 10 to 50 parts by mass, and the urea is 2 to 30 parts by mass, and further, the proportion of polyolefin is 60 to 88 parts by mass, It is preferable that the proportion of low molecular weight starch is 10 to 20 parts by mass and that of urea is 2 to 20 parts by mass. In this case, regardless of the type of polyolefin or low-molecular-weight starch, the dispersibility of low-molecular-weight starch in polyolefin is improved, and a composite resin composition in which low-molecular-weight starch is dispersed in polyolefin can be obtained.

Kneading to obtain the composite resin composition of the present invention can be carried out using a conventionally known method, for example, using a mixer such as a Banbury mixer, a kneader, various extruders, and the like. The kneading conditions can be appropriately determined depending on the type and amount of each component, the kneader used, and the like. For example, when using a kneader or Banbury mixer, the temperature is 140 to 200°C, preferably 150 to 190°C, and it is appropriate to knead at this temperature for 1 to 180 minutes, preferably 3 to 120 minutes.

There is no particular restriction on the order in which the above-mentioned components are added during kneading. However, it is preferable that the polyolefin, low-molecular-weight starch, and urea are simultaneously introduced into a kneader and kneaded. This improves the effects of urea addition as described above. Furthermore, the low-molecular-weight starch easily diffuses into the polyolefin, making it possible to obtain a composite resin composition with less starch aggregates.

The above-mentioned starch aggregates include starch aggregates with a diameter of 5 μm or more.

After kneading, the mixture is left to cool, for example, to obtain a composite resin composition, or it is molded into a powder, pellet, flake, or the like as a raw material for molding. However, depending on the case, it is also possible to form the composite resin composition obtained by kneading into a desired molded article as it is.

The composite resin composition thus obtained can be formed by pressure molding, film molding, extrusion molding, injection molding, press molding, filling, molding, inflation molding, vacuum forming, blow molding, foam bead molding, emulsion bead molding. Various molded products can be produced by appropriately molding into desired shapes by means such as spray bead molding.

The composite resin composition of the present invention may also contain fillers (e.g., glass fiber, talc), flame retardants (e.g., chlorine-based flame retardants, phosphorus-based flame retardants, brominated flame retardants, inorganic flame retardants), as needed. (flame), antioxidants (e.g., phenolic antioxidants, phosphorus antioxidants, amine antioxidants), clarifying agents, plasticizers, and antistatic agents. It may also contain raw materials to be blended.

The present invention will be explained in further detail by giving test examples below.

(Compoundability evaluation)
To evaluate the compoundability, 0.68 g of the obtained composite resin composition was compressed under a load of 0.5 t using a heat press machine (manufactured by AS ONE, H300-1) heated to 140°C to 170°C. , a compound film was obtained. The obtained compound film was observed using a microscope (manufactured by Keyence Corporation, VHX-5000) to evaluate the dispersibility of starch used as a filler. If no unmelted particles are confirmed, the evaluation result is ◎; if a few unfused particles are confirmed, the evaluation result is ○; if a large number of unfused particles are confirmed, the evaluation result is ×; an evaluation of ○ or higher is given. I judged that I passed. Further, the area ratio was determined by automatically calculating the area after the above observation and calculating the area occupancy ratio of starch aggregates of 5 μm or more in the film.

(RVA peak viscosity)
It was measured as follows using a rapid viscoanalyzer (RVA) (manufactured by Perten Instruments). 30g of a dispersion liquid was prepared by dispersing starch in water to a concentration of 10% by mass, and held at 50°C for 1 minute while stirring at 160 rpm with a paddle. ℃, kept at 95℃ for 2 minutes and 30 seconds, continuously cooled to 50℃ for 3 minutes and 48 seconds, and held at 50℃ for 2 minutes to reach the peak. The viscosity (maximum viscosity) was measured.

(Particle size distribution measurement)
The particle size distribution was analyzed using a dynamic light scattering analyzer (ELSZ-2000ZS manufactured by Otsuka Electronics Co., Ltd.) as described below. A dispersion liquid was prepared by diluting the paste liquid immediately after measurement with a rapid viscoanalyzer (RVA) with distilled water until the solid content concentration became 0.02% by mass, and the dispersion liquid was filled into a glass standard cell, and the number of integration times was 25. Measurement was carried out under room temperature conditions, using the refractive index, viscosity, and dielectric constant of the solvent using the values of water. The difference between the maximum particle size and the minimum particle size was calculated from the measured values.

In addition to the compounding property, notes are entered if there is anything noteworthy regarding the film forming property during hot pressing of the test example and the coloring of the composite resin composition. The composite resin composition is considered to be colored if it is visually confirmed by comparison with the raw material high-density polyethylene pellets and polypropylene pellets.

(Test example)

Test examples 1 to 6
In order to achieve the proportions shown in Table 1, 50 to 90 parts by mass of high-density polyethylene (manufactured by Prime Polymer Co., Ltd., Hi-ZEX 2100JH), low-molecular corn starch (gelatinization treatment using a drum dryer as the method of low-molecularization) was selected ( A pressure kneader (Ms type pressure kneader DS1-5MHA-E type, manufactured by Nippon Spindle Co., Ltd.) in which 10 parts by mass of Ulster E (manufactured by Nippon Shokuhin Kako Co., Ltd.) and 0 to 40 parts by mass of urea were preheated to 150°C. was introduced at the same time. The mixture was kneaded at a rotational speed of 40 rpm until the resin temperature reached 140°C. After kneading, the kneaded material was transferred to an aluminum vat and allowed to cool to obtain the desired composite resin composition.

Test examples 7 to 16
25 to 90 parts by mass of high-density polyethylene, a heating low-molecularization treatment by adding a halide salt and a gelatinization treatment using a drum dryer were selected to achieve the proportions shown in Table 2. 10 to 50 parts by mass of molecularized starch A and 0 to 40 parts by mass of urea were simultaneously charged into a pressure kneader (Ms type pressure kneader DS1-5MHA-E type manufactured by Nippon Spindle Co., Ltd.) that had been previously heated to 150°C. The mixture was kneaded at a rotational speed of 40 rpm until the resin temperature reached 140°C. After kneading, the kneaded material was transferred to an aluminum vat and allowed to cool to obtain the desired composite resin composition.

Note that low-molecular-weight starch A is a low-molecular-weight starch that has been subjected to heating low-molecularization treatment by adding a halide salt as explained above and gelatinization treatment using a drum dryer, and was produced as follows. . That is, calcium chloride was added to 20 parts by mass of water in an amount of 3 parts by mass based on the mass of starch, and dissolved in advance. An aqueous calcium chloride solution was added to 100 parts by mass of cornstarch, and the mixture was stirred using a blender until it became homogeneous. After stirring, the mixture was transferred onto a stainless steel vat, and starch was dispersed therein to a thickness of 10 mm or less. The aluminum bat was transferred to an oven preheated to 130°C, and heat treatment was performed. After the heat treatment, it was allowed to cool at room temperature for 30 minutes. After cooling, 2000 parts by mass of water was added to 100 parts by mass of the dry mass of starch, and the mixture was washed with water, dehydrated, and then dried. The obtained low-molecular-weight starch has an RVA peak viscosity of 10% by mass size liquid that is 1.8% of the RVA peak viscosity of the raw material untreated starch, and the difference between the maximum particle size and the minimum particle size is 420.6 nm. Met. Furthermore, the obtained low-molecular-weight starch was subjected to gelatinization treatment using a drum dryer to obtain low-molecular-weight starch A.

Test examples 17-20
A composite resin composition was obtained in the same manner as in Test Example 2, except that the type of starch was changed and various starches shown in Table 3 were used. In Test Example 17, untreated corn starch that had not been subjected to a low molecular weight treatment was used. Low-molecular-weight starch B was obtained by performing low-molecular-weight starch treatment in the same manner as low-molecular-weight starch A, but without gelatinization treatment. Test Examples 19 and 20 were chemically modified starches such as urea phosphorylated starch, which is esterified starch, and carboxymethylated starch, which is etherified starch. Modified starch was used.

Test example 21
80 parts by mass of polypropylene (Sun Allomer PM600A, manufactured by Sun Allomer Co., Ltd.), 10 parts by mass of low molecular weight starch A, and 10 parts by mass of urea were heated in advance to 180°C in a pressure kneader (Ms type pressure kneader manufactured by Nippon Spindle Co., Ltd.). DS1-5MHA-E type) at the same time. The mixture was kneaded at a rotational speed of 40 rpm until the resin temperature reached 170°C. After kneading, the kneaded material was transferred to an aluminum vat and allowed to cool to obtain the desired composite resin composition. Note that the same low-molecular-weight starch A as used in Test Examples 7 to 16 was used.

Test example 22
80 parts by mass of high-density polyethylene, 10 parts by mass of low-molecular starch A, and 10 parts by mass of urea were added to a cylinder using a twin-screw extruder (Parker Corporation's co-rotating twin-screw extruder HK25D, φ25, L/D=41). The mixture was melt-kneaded and extruded at a temperature of 150°C. After cooling the strand in water, it was cut with a pelletizer to obtain a pellet-shaped composite resin composition. Note that the same low-molecular-weight starch A as used in Test Examples 7 to 16 was used.

Test example 23
10 parts by mass of low-molecular-weight starch A and 10 parts by mass of urea were mixed in advance, spread in an aluminum bat to a thickness of 5 mm, and dried in a vacuum dryer at 40° C. for 12 hours to obtain a dry mixture. 20 parts by mass of the obtained dry mixture and 80 parts by mass of high-density polyethylene were simultaneously charged into a pressure kneader (Ms type pressure kneader DS1-5MHA-E type manufactured by Nippon Spindle Co., Ltd.) that had been preheated to 150 ° C. . The mixture was kneaded at a rotational speed of 40 rpm until the resin temperature reached 140°C. After kneading, the kneaded material was transferred to an aluminum vat and allowed to cool to obtain the desired composite resin composition. Note that the same low-molecular-weight starch A as used in Test Examples 7 to 16 was used.

Test example 24
76 parts by mass of high-density polyethylene, 10 parts by mass of low-molecular starch A, 10 parts by mass of urea, and 4 parts by mass of unsaturated dicarboxylic acid (maleic anhydride) were preheated to 150°C in a pressure kneader (manufactured by Nippon Spindle Co., Ltd.). The mixture was simultaneously charged into a Ms type pressure kneader DS1-5MHA-E type). The mixture was kneaded at a rotational speed of 40 rpm until the resin temperature reached 140°C. After kneading, the kneaded material was transferred to an aluminum vat and allowed to cool to obtain the desired composite resin composition. Note that the same low-molecular-weight starch A as used in Test Examples 7 to 16 was used.

Test example 25
77 parts by mass of high-density polyethylene, 10 parts by mass of low-molecular starch A, 10 parts by mass of urea, and 3 parts by mass of a compatibilizer (manufactured by Kayaku Nourion Co., Ltd., Kayabrid: maleic anhydride-modified polypropylene) were heated to 150°C in advance. The mixture was simultaneously charged into a pressurized kneader (Ms type pressurized kneader DS1-5MHA-E type manufactured by Nippon Spindle Co., Ltd.). The mixture was kneaded at a rotational speed of 40 rpm until the resin temperature reached 140°C. After kneading, the kneaded material was transferred to an aluminum vat and allowed to cool to obtain the desired composite resin composition. Note that the same low-molecular-weight starch A as used in Test Examples 7 to 16 was used.

In Test Examples 1 to 6, composite resin compositions with excellent dispersibility were produced by adding 10 parts by mass of low molecular weight starch and 5 to 30 parts by mass of urea to 60 to 85 parts by mass of high-density polyethylene. It has been found that a composite resin composition with good compoundability can be obtained. In addition, in Test Examples 7 to 16, dispersibility was improved by manufacturing a composite resin composition by adding 25 to 88 parts by mass of high-density polyethylene, 10 to 50 parts by mass of low molecular weight starch A, and 2 to 25 parts by mass of urea. It has been found that a composite resin composition with excellent compounding properties can be obtained. However, it can be seen that when the amount of urea increases beyond 40 parts by mass, the film formability decreases.

For reference, an enlarged photograph of Test Example 11 is shown in FIG. The photograph was observed with a microscope (200x, polarization stage, transmitted light, high-quality mode).

Therefore, by comparing Test Examples 1 to 6 and Test Examples 7 to 16, it was found that by using low molecular weight starch A, which was reduced in molecular weight using a halide salt as the low molecular weight starch, a smaller amount of urea was used. It can be seen that a composite resin composition with excellent compoundability can be obtained.

In addition, regardless of the type of starch, etc., the composite resin composition should exhibit good compoundability by containing 25 to 88 parts by mass of polyolefin, 10 to 50 parts by mass of starch, and 2 to 30 parts by mass of urea. I understand.

As shown in Test Example 17, it can be seen that when corn starch that has not been reduced to a low molecular weight is used, the compoundability is poor. For reference, an enlarged photograph of Test Example 17 is shown in FIG. The photograph was observed with a microscope (200x, polarization stage, transmitted light, high-quality mode). The black parts in the figure correspond to starch aggregates, and as is clear from FIG. 2, it can be seen that there are many starch aggregates in this example.

From Test Examples 18 to 20, when low-molecular starch without gelatinization treatment using a drum dryer was used as starch, or starch in which esterified starch and etherified starch were subjected to gelatinization treatment as low-molecularization treatment. It can be seen that the obtained composite resin composition also exhibits good compoundability.

Further, as shown in Test Example 21, it can be seen that even when the polyolefin was changed from high density polyethylene to polypropylene, the obtained composite resin composition showed good compoundability. Furthermore, as shown in Test Example 22, it can be seen that even when the kneader was changed from a pressure kneader to a twin-screw extruder, the obtained composite resin composition exhibited good compoundability.

On the other hand, as shown in Test Example 23, in a composite resin composition obtained by premixing low-molecular-weight starch A and urea to obtain a mixture, and then mixing high-density polyethylene with this mixture, polyolefin, starch It can be seen that the compoundability is inferior to that of a composite resin composition obtained by simultaneously charging and kneading urea and urea into a kneader. It can also be seen that it is inferior in terms of coloring.

Furthermore, as shown in Test Examples 24 and 25, when an unsaturated dicarboxylic acid or a dispersant is added to the composite resin composition in addition to high-density polyethylene, low-molecular-weight starch A, and urea, compoundability and coloring may be reduced. It turns out that the quality is inferior.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

Claims (6)

In polyolefin, acid-treated starch, alkali-treated starch, oxidized starch, enzyme-treated starch, starch mixed with metal salts, heat-treated starch, pulverized starch, extrusion-treated starch, pregelatinized starch, radical-treated starch, radiation-treated starch At least one selected from the group consisting of starch, electron beam treated starch, microwave treated starch, ultrasonic treated starch, high frequency treated starch, pressure treated starch, milled starch, powder collision treated starch, and friction treated starch is dispersed. A composite resin composition containing urea and having an area occupation rate of starch aggregates in the film of 5% or less. The composite resin composition according to claim 1 , wherein the treated starch is a pregelatinized starch. The treated starch is characterized in that the RVA peak viscosity of the 10% by mass size liquid is 5% or less of the RVA peak viscosity of the untreated starch as a raw material, and the difference between the maximum particle size and the minimum particle size is 2 μm or less. The composite resin composition according to claim 1 or 2 . 4. The method according to claim 1, wherein the polyolefin is contained in a proportion of 25 to 88 parts by weight, the treated starch is 10 to 50 parts by weight, and the urea is contained in a proportion of 2 to 30 parts by weight. Composite resin composition. The composite resin composition according to any one of claims 1 to 4 , wherein the polyolefin is unmodified. 6. The method for producing a composite resin composition according to claim 1 , wherein the polyolefin is mixed with an acid-treated starch, an alkali-treated starch, an oxidized starch, an enzyme-treated starch, or a metal salt. , heat treated starch, pulverized starch, extrusion treated starch, pregelatinized starch, radical treated starch, radiation treated starch, electron beam treated starch, microwave treated starch, ultrasonic treated starch, high frequency treated starch, pressure treated starch, milling A composite resin composition, characterized in that it is produced by simultaneously charging at least one selected from the group consisting of treated starch, powder collision treated starch, and friction treated starch, and the above-mentioned urea into a kneader and kneading them. manufacturing method.