JPH07207113A - Production of biodegradable resin composition - Google Patents

Abstract

PURPOSE:To obtain a biodegradable resin composition having an accelerated biodegradability when buried in soil, garbage, compost, etc., by kneading a thermoplastic resin with oils, etc., and an organic peroxide compound. CONSTITUTION:This composition is obtained by kneading (A) a thermoplastic resin (preferably polyethylene) with (B) an oil and/or an oxidized oil, (C) an organic peroxide [preferably dicumyl peroxide, alpha, alpha'-bis(t-butylperoxy-m- isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane or 2,5-dimethyl-2,5-di(t- butylperoxy)hexyne-3] and optionally (D) starch and/or a modified starch, (E) a metal salt, a metal oxide or a metal hydroxide and (F) an oxidized wax, at a temperature higher than the softening temperature of the resin A.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a biodegradable resin composition. More specifically, it relates to a method for producing a biodegradable resin composition by heating and kneading a thermoplastic resin together with oil and an organic peroxide.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 49-55,740 and corresponding U.S. Pat. No. 4,016,117 disclose organisms containing starch particles dispersed in a thermoplastic resin or a thermosetting elastomer resin. A degradable resin composition is disclosed.

Japanese Patent Publication No. 52-42,187 discloses carbon, a synthetic resin based on carbon bonds, biodegradable particles such as natural starch granules, and at least one double bond in one molecule. Biodegradable compositions containing saturated fatty acids or their derivatives are disclosed.

Japanese Patent Publication No. 60-41,089 contains starch particles and a synthetic resin which are made hydrophobic by reacting the surface of the starch particles with a compound which easily reacts with a hydroxyl group to form an ether or an ester. Biodegradable compositions are disclosed.

Further, Japanese Patent Publication No. 56-44,907 discloses a higher alcohol having a straight chain, a higher alcohol having a straight chain higher fatty acid methyl branch, a higher fatty acid having a methyl branch, an ester thereof, and a dimer of a straight chain higher fatty acid. -And tri-glyceride, di- of higher fatty acid having methyl branch
And at least one kind of organic substance and inorganic substance selected from the group consisting of tri-glyceride, and the amount of the organic substance is 2% or more, and the total amount of the organic substance and the inorganic substance is 60%. A biodegradable polyolefin composition characterized by not exceeding is disclosed.

In the publication, when the above-mentioned polyolefin composition is irradiated with ultraviolet rays and then subjected to a JIS mold resistance test, a certain composition range, that is, myristyl myristate 2 to
With a polyethylene composition containing 10% and 30 to 40% calcium carbonate, the deterioration of strength is dramatically accelerated. This means that when the resin material is dumped outdoors, it is likely to be rapidly decomposed. It is described that it means.

Also, Professor Osawa of the Department of Materials Engineering, Faculty of Engineering, Gunma University, prepared a composition in which 10% cornstarch was added to an ethylene / carbon monoxide copolymer and a composition in which 70% paper was added to the copolymer. Then, irradiate them with ultraviolet light for 24 hours using a high-pressure mercury lamp or expose them outdoors, and then bury them indoors or outdoors to measure the weight loss rate, which is about twice that of ethylene / carbon monoxide copolymer alone. It has been described that the weight loss rate was shown (Nippon Kogyo Shimbun, March 1992).
9th).

Regarding a method of promoting photodegradation of a polymer substance using ultraviolet rays, Japanese Patent Application Laid-Open No. 61-285,226, which is an inventor of which one of the inventors of the present application is the inventor, discloses the two-step ultraviolet irradiation. Is disclosed.

[0009]

An object of the present invention is to provide a novel biodegradable resin composition. Another object of the present invention is to provide a method for producing a novel biodegradable resin composition in which biodegradation is advantageously progressed by being buried in soil, garbage, compost or the like.

A further object of the present invention is a novel biodegradable resin which has UV degradability and is decomposed by UV irradiation and then buried in soil, garbage or compost so that the biodegradation proceeds more advantageously. It is to provide a method of manufacturing a composition. Further objects and advantages of the present invention will be apparent from the following description.

[0011]

According to the present invention, the above objects and advantages of the present invention include (a) a thermoplastic resin and (b)
It is achieved by a method for producing a biodegradable resin composition, which comprises kneading an oil and / or an oxidized oil and (c) an organic peroxide at a temperature not lower than the softening temperature of the thermoplastic resin (a).

As the thermoplastic resin (a), a general thermoplastic resin can be used without particular limitation. For example, a polyolefin resin comprising a homopolymer or copolymer of α-olefin such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, or a copolymer of these α-olefin and another comonomer; Polystyrene resin; ABS resin; polyvinyl chloride resin; polyvinylidene chloride-vinyl copolymer resin; polycarbonate resin; polyester resin; polyamide resin; polyphenylene oxide resin; polyvinyl alcohol resin (ethylene-vinyl acetate copolymer Saponified polymer); polyurethane resin; polyether resin; rubbers such as natural rubber, isoprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, and mixtures thereof. . Among these, it is preferable to use a polyolefin resin or a polystyrene resin.

As the oil and the oxidized oil (b), animal oil,
Vegetable oils and those obtained by oxidizing them are preferably used. Above all, those obtained by oxidizing vegetable oil by boiling or the like are preferable. The boiling time is not particularly limited, but it is preferably 5 hours or more. Examples of preferable vegetable oil include rapeseed oil, corn oil, sunflower oil, safflower oil and the like. By using those obtained by oxidizing these vegetable oils, the oxidation start temperature of the resin composition is lowered, and biodegradability is promoted. The blending amount of the oil and / or the oxidizing oil is preferably 0.1 with respect to the thermoplastic resin.
10 to 10% by weight, more preferably 0.3 to 5% by weight. When the blending amount of oil and / or oxidized oil is 0.1% by weight or more, the biodegradability increases as the amount increases. However, if it exceeds 10% by weight, the deterioration of the physical properties of the resin tends to be remarkably large, and it tends to be impractical.

The organic peroxide (c) is represented by the following formula (1) R-O-O-R '... (1) (wherein R and R'are the same or different and are alkyl. Group, an aryl group or an aralkyl group) or the following formula (2)

[0015]

[Chemical 2]

A compound represented by the formula (wherein R and R'are the same as defined above) is preferably used.

The organic peroxides included in the above formulas (1) and (2) are known per se. Organic peroxide (c)
Examples include dicumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2, 5-dimethyl-2,5-di (t-
Examples thereof include compounds included in the above formula (1) such as butylperoxy) hexyne-3, and compounds included in the above formula (2) such as dibenzoylperoxide. Of these, dicumyl peroxide is particularly preferable. The blending amount of the organic peroxide (c) is preferably 0.001 to 0.16% by weight, more preferably 0.005 to 0.14% by weight, based on the thermoplastic resin. If the amount of the organic peroxide is too large, the crosslinking of the thermoplastic resin is prioritized, and the structure of the composition becomes too hard and dense, so that the biodegradability tends to decrease.

The method of the present invention is carried out by kneading the above-mentioned components (a), (b) and (c) at a temperature not lower than the softening point of the thermoplastic resin of the component (a). The suitable kneading temperature depends on the thermoplastic resin. For example, when the thermoplastic resin is polyethylene, a suitable kneading temperature is 160 to
It is in the range of 220 ° C. The kneading can be performed by a conventionally known kneading device such as an open mixing roll, a non-open Banbury mixer, a kneader, a single screw extruder, or a twin screw extruder. The biodegradable resin composition obtained by the method of the present invention comprises, in addition to the components (a), (b) and (c) described above, (d) starch and / or modified starch, (e) metal salt, metal A metal compound selected from the group consisting of oxides and metal hydroxides and at least one component of (f) oxidized wax can be contained. Examples of the starch or modified starch (d) include starch obtained from rice, corn, potato, sweet potato, wheat, or the like; or a starch obtained by grafting a polymerizable monomer such as styrene on the starch, or a product coated with silicon or the like, or Examples thereof include starch-modified products which contain sugars such as lactose and glucose, sugar-containing, casein sugar as a main component, and which are modified with an organic substance which organisms prefer to ingest.

The blending amount of starch and / or modified starch is preferably 5 to 70 relative to the thermoplastic resin (a).
%, More preferably 7 to 20% by weight. The biodegradability increases as the amount of starch and / or modified starch is increased. However, if it exceeds 70% by weight, the deterioration of the physical properties of the resin tends to be remarkably large, and it tends to be impractical.

As the metal compound (e), for example, at least one metal salt of a metal selected from the group consisting of Na, K, Ca, Mg, Zn, Al, Mn and Fe,
A metal oxide or a metal hydroxide is preferably used. The metal salt is preferably an inorganic acid salt or an organic carboxylic acid salt. Further, as the organic carboxylic acid salt, a higher aliphatic carboxylic acid salt is particularly preferable. Examples of the inorganic acid include sulfuric acid,
Hydrochloric acid, carbonic acid and the like are preferable, and as the higher aliphatic carboxylic acid, a saturated aliphatic carboxylic acid having 10 to 30 carbon atoms and an unsaturated aliphatic carboxylic acid are preferable. As the metal, iron, aluminum and the like are particularly preferable. These metal compounds may be used alone or in combination of two or more kinds. Especially when the metal salt of an inorganic acid and the metal salt of a higher aliphatic carboxylic acid are used in combination, the biodegradability is remarkably improved.

The amount of the metal compound compounded is preferably 0.1 to 30% by weight, more preferably 0.3 to 10% by weight, based on the thermoplastic resin (a). The biodegradability increases as the amount of the metal compound added increases. However, if it exceeds 30% by weight, the deterioration of the physical properties of the resin tends to be remarkably large, and it tends to be impractical. As the oxidized wax (f), a commercially available product that can be obtained as an oxide of wax can be used as it is. The blending amount of the oxidation wax is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight, based on the thermoplastic resin.

When using the above-mentioned components (d), (e) and (f) having optional components, in the same manner as above, at a temperature above the softening point of the thermoplastic resin of the component (a), a),
It is advantageous to knead with the components (b) and (c). In addition, the components (a) to (c) and (d) to (f) can be premixed in any combination of two or more components in advance, or can also be prepared as a masterbatch.

The biodegradable resin composition obtained by the method of the present invention is, for example, a film, sheet, tape, yarn, string,
Materials for packaging such as nets, industrial materials such as civil engineering and fisheries, shopping bags, garbage bags, light weight packaging bags, diaper films, agricultural mulch films, soft drink carriers,
Sandbag, curing sheet, direct net, food container, tableware,
It can be in various forms such as a container such as a bucket, a toy, and a medical device. These molded bodies can be manufactured by various molding methods such as masterbatch, extrusion molding, injection molding, inflation molding, calender molding, blow molding and rotational molding.

The biodegradable resin composition of the present invention is a rubber, a plasticizer, a lubricant, an ultraviolet absorber, another antioxidant, a foaming agent, a cross-linking agent, an antistatic agent, within the scope of the present invention. Additives such as agents, anti-violent agents, flame retardants, coloring agents, and fillers can be contained.

The biodegradable resin composition obtained by the present invention is
When placed in contact with a biodegradation medium such as soil, garbage, sludge, or compost, it undergoes biodegradation by microorganisms present in the biodegradation medium and gradually loses its original form. Further, the biodegradable resin composition obtained in the present invention also has a property of being decomposed by ultraviolet rays, and therefore, for example, after being decomposed by irradiation of sunlight, if buried in soil or the like,
Its biodegradability is achieved more quickly. The contact temperature with the biodegradation medium is preferably about 10 to 45 ° C. Soil, garbage and compost can be used alone or mixed together. The resin composition and these biodegradable media such as soil should be placed in as close contact as possible. For example, when the resin composition is in the form of a film, it is desirable that both the front and back surfaces come into contact with the biodegradable medium while the film is well stretched.

[0026]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to such examples.

Example 1 (1). Low density polyethylene (manufactured by Nippon Petrochemical Co., Ltd.,
F-31N), 43% by weight of modified starch obtained by treating the surface of corn starch with a silane coupling agent, at 300 ° C.
6% by weight of rapeseed oil boiled for 2 hours and 8% by weight of calcium oxide, 5.0% by weight of aluminum hydroxide, 5.0% by weight of aluminum sulfate, iron stearate
5.0 wt%, oxidized wax 5.0 wt% and dicumyl peroxide 0.2 wt% were blended and mixed by dry blending using a Hensyl mixer. This mixture was melt-mixed by an extruder to obtain high-concentration master batch pellets.

This masterbatch pellet was added to low-density polyethylene (F-31 manufactured by Nippon Petrochemical Co., Ltd.)
N) was blended in an amount of 10 wt% and dry-mixed, and then a film having a thickness of 50 μm was produced by an inflation molding method using an extruder having a screw diameter of 40 mmφ.
Test pieces were formed from this film. The amount of each component in the test piece was 4.3% by weight of modified starch and 0.6 of oxidized rapeseed oil.
% By weight, calcium oxide 0.8% by weight, aluminum hydroxide 0.5% by weight, aluminum sulfate 0.5% by weight, iron stearate 0.5% by weight, oxidized wax 0.5% by weight.
And dicumyl peroxide was 0.02% by weight.

(2). Test pieces of the above film were embedded in garbage and forest soil for about 5 months. On the piece buried in raw garbage for 5 months, there were few holes and a brown discolored portion was observed by visual observation. Moreover, the tensile strength and elongation of the buried pieces for 5 months of garbage are 94% respectively compared to the test pieces before buried.
And a value of 100%. On the other hand, the tensile strength and elongation of the specimen embedded in the forest for 5 months were 92% and 73%, respectively, as compared with the test specimen before burying. In addition, the oxidation start temperature of the garbage for 5 months and the forest for 5 months was 2 each.
06.3 ° C and 209.4 ° C. The temperature of the test piece before embedding was 210.6 ° C. Also, the microscope F
The results of measuring the functional groups by T-IR are shown in Table 1. Table 1 shows the concentration of each characteristic absorption peak.
It was shown as the absorbance ratio with the absorbance at 0 cm ^-1 . The characteristic absorption peaks are identified as follows. 1710 cm ⁻¹ : Absorption by carboxylic acid produced by oxidative deterioration and decomposition 1745 cm ⁻¹ : Absorption of ester produced by reduction and deterioration of carbonyl group derived from oil, decomposition 880 cm ⁻¹ : By peroxide (—O—O—) Absorption 1640 cm ^-1 : Absorption by carbon-carbon double bond (> C = C <)

Example 2 (1). Except for the fact that 20% by weight of the master batch pellets was added to the low-density polyethylene with no additive added, the same procedure as in Example 1 was carried out. The content of each component in the test piece was 8.6% by weight modified starch, 1.2% by weight oxidized rapeseed oil, 1.6% by weight calcium oxide, 1.0% by weight aluminum hydroxide, and 1.
It was 0% by weight, iron stearate 1.0% by weight, oxidized wax 1.0% by weight and dicumyl peroxide 0.04% by weight. (2). A test piece of the above film was embedded in garbage and forest soil for about 5 months. Visual observation revealed that the buried piece of raw garbage for 5 months had many pores, was strongly discolored, and was partially shrunk. Further, the tensile strength and elongation of the embedded pieces of raw garbage for 5 months showed values of 108% and 87%, respectively, as compared with the test pieces before embedded. On the other hand, the tensile strength and elongation of the specimens buried in the forest for 5 months are 1 each as compared with the specimens before burying.
10% and 107%. In addition, the oxidation start temperature of the garbage for 5 months and the forest for 5 months was 2 each.
It was 06.0 ° C and 201.0 ° C. The temperature of the test piece before embedding was 208.3 ° C. Also, the microscope F
The results of measuring the functional groups by T-IR are shown in Table 1. Table 1 shows the concentration of each characteristic absorption peak.
It was shown as the absorbance ratio with the absorbance at 0 cm ^-1 .

Example 3 (1). A masterbatch containing 0.4% by weight of dicumyl peroxide was obtained in the same manner as in Example 1 (1). Others were the same as in Example 1. The content of each component in the test piece was 4.3% by weight modified starch, 0.6% by weight oxidized rapeseed oil, 0.8% by weight calcium oxide, 0.5% by weight aluminum hydroxide, 0.5% aluminum sulfate. % By weight, iron stearate 0.5% by weight, oxide wax 0.5% by weight and dicumyl peroxide 0.02% by weight. (2). A test piece of the above film was embedded in garbage and forest soil for about 5 months. A piece of raw garbage that had been buried for 5 months had some voids and a brown discolored portion was observed by visual observation. In addition, the tensile strength and elongation of the buried pieces for 5 months were 99% and 9%, respectively, compared with the test pieces before buried.
A value of 4% was shown. On the other hand, the tensile strength and elongation of the specimens buried in the forest for 5 months are 101% respectively compared to the specimens before embedding.
And 94%. In addition, the oxidation start temperature of the raw waste for 5 months and the forest for 5 months was 204.7 each.
And 207.3 ° C. The temperature of the test piece before embedding was 211.0 ° C. In addition, the microscope FT-I
The measurement result of the functional group by R is shown in Table 1. In Table 1, the concentration of each characteristic absorption peak is 1470 cm.
^It is shown as the absorbance ratio at ^-1 .

Example 4 (1). The same procedure as in Example 1 was carried out except that 20% by weight of the low-density polyethylene containing no master batch was added to the master batch pellets. The content of each component in the test piece was 8.6% by weight modified starch, 1.2% by weight oxidized rapeseed oil, 1.6% by weight calcium oxide, 1.0% by weight aluminum hydroxide, 1.0% aluminum sulfate. % By weight Iron stearate 1.0% by weight, oxidized wax 1.0
% By weight and 0.08% by weight of dicumyl peroxide. (2). A test piece of the above film was embedded in garbage and forest soil for about 5 months. The piece of raw garbage that had been buried for 5 months had some voids when observed with the naked eye, and dark discoloration and partial shrinkage were observed. Further, the tensile strength and the elongation of the buried piece of raw garbage for 5 months (the portion having no voids caused by the burying) were 83% and 100%, respectively, as compared with the test piece before burying. On the other hand, the tensile strength and elongation of the specimens buried in the forest for 5 months are 106% and 94%, respectively, compared to the specimens before burying.
Met. Furthermore, the oxidization start temperatures of the garbage for 5 months and the forest for 5 months are 195.5 ° C and 20 respectively.
It was 3.9 ° C. The test piece before burying is 20
It was 6.4 ° C. Further, the measurement results of the functional groups by the microscope FT-IR are as shown in Table 1. In Table 1,
The concentration of each characteristic absorption peak is shown as the absorbance ratio with the absorbance at 1470 cm ^-1 .

[0033]

[Table 1]

Example 5 (1). Low density polyethylene (manufactured by Nippon Petrochemical Co., Ltd.,
F-31N), 43% by weight of modified starch obtained by treating the surface of corn starch with a silane coupling agent, 6% by weight of soybean fat and 8% by weight of calcium oxide, 5.0% by weight of aluminum hydroxide, 5.0% by weight of aluminum sulfate. %, Iron stearate 5.0% by weight, oxidized wax 5.0% by weight and dicumyl peroxide 0.4% by weight, and mixed by dry blending using a Hensyl mixer.
This mixture was melt-mixed by an extruder to obtain high-concentration master batch pellets.

This masterbatch pellet was added to low-density polyethylene (F-31 manufactured by Nippon Petrochemical Co., Ltd.)
After blending 20% by weight of N) and dry mixing, a film having a thickness of 50 μm was produced by an inflation molding method using an extruder having a screw diameter of 40 mmφ.
Test pieces were formed from this film. The content of each component in the test piece was 8.6% by weight modified starch, 1.2% by weight soybean oil, 1.6% by weight calcium oxide, 1.0% by weight aluminum hydroxide, 1.0% by weight aluminum sulfate. %, Iron stearate 1.0% by weight, oxidized wax 1.0% by weight and dicumyl peroxide 0.08% by weight.

(2) A test piece of the above film was embedded in forest soil for about 8 months. During that time, film test pieces were dug up at appropriate intervals, and the breaking elongation and the absorbance of the characteristic absorption peak by FT-IR were measured. The results are shown in FIGS. 1, 2 and 3 of the accompanying drawings. In these figures, the curve B is the result when the film of the present invention is embedded in forest soil, and the curve A is the same as the above composition except that dicumyl peroxide is not blended. It is a result when the comparative film from is embedded in the forest soil. Curve A ′ in FIG. 1 is the result when the film of the present invention was left indoors (in a dark place). It can be seen that the film of the present invention, when embedded in soil, has a significantly reduced elongation at break and a large increase in carbonyl groups and peroxide bonds.

Example 6 The same film as the film of the present invention used in Example 5 was prepared (B). Further, in the same manner as in Example 5, the film of the present invention (C) and 0 of Example 5 were different from the film of the present invention of Example 5 only in that the amount of dicumyl peroxide was 0.12% by weight. A comparative film (D) was prepared separately, which differed only in that it was .16% by weight. After heat treatment of these three kinds of films in a gear oven at 90 ° C. for 12 days, 2
It was immersed in distilled water for 4 hours. Then, the water absorption amount of each film sample was measured. The results are shown in Fig. 4. The films (B) and (C) of the present invention gradually absorb more water as the heat treatment time increases, whereas the comparative film (D) having a large peroxide content also absorbs more water than the film of the present invention. It can be seen that the amount is very small. It is presumed that the comparative film (D) has a structure in which the crosslinking reaction preferentially proceeds, the structure becomes dense, and the infiltration of water is small.

Example 7 The same inventive film B and comparative film A used in Example 5 and low density polyethylene (LDPE, F31)
N) comparative films A "were prepared. These films were subjected to a photo-deterioration test with a sunshine weather meter. The results are shown in Fig. 5. The photo-deterioration of the film A of the present invention was shown to be rapid. When the film of the present invention is thus photo-deteriorated and then embedded in soil or the like, its biodegradability is further promoted.

[0039]

EFFECTS OF THE INVENTION According to the present invention, a novel biodegradable resin composition which is buried in soil, garbage, compost or the like to promote biodegradation can be advantageously produced.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a film embedding period and a breaking elongation.

FIG. 2 is a relationship diagram between a film embedding period and a characteristic absorption peak (1710 cm ⁻¹ ) by FT-IR.

FIG. 3 is a diagram showing a relationship between a film embedding period and a characteristic absorption peak (880 cm ⁻¹ ) by FT-IR.

FIG. 4 is a diagram showing the relationship between the heat treatment time of a film and the water absorption amount.

FIG. 5 is a diagram showing a relationship between heat treatment time of a film and photodegradation by a sunshine weather meter.

[Explanation of symbols]

 A comparative film B film of the present invention C film of the present invention D comparative film A'film of the present invention (leaved indoors) A "comparative film (polyethylene)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C08L 23/06 LCW (72) Inventor Shinnao Murakami 4-1-1 Hommachi, Chuo-ku, Osaka-shi, Osaka No. Takenaka Corporation Osaka Main Store (72) Inventor Takashi Hirayama 4-16-30 Kitaune, Kurashiki City, Okayama Prefecture (72) Inventor Hitoshi Asabe, 2111-1 Chayamachi, Kurashiki City, Okayama Prefecture

Claims (7)

[Claims] 1. A thermoplastic resin, (b) oil and / or
Alternatively, a method for producing a biodegradable resin composition, which comprises kneading an oxidized oil and (c) an organic peroxide at a temperature equal to or higher than the softening temperature of the thermoplastic resin (a). 2. The method according to claim 1, wherein in addition to the components (a), (b) and (c), (d) starch and / or modified starch is kneaded together. 3. In addition to the above components (a), (b) and (c) or in addition to the above components (a), (b), (c) and (d), a metal salt (e), A method according to claim 1 or 2 in which a metal compound selected from the group consisting of metal oxides and metal hydroxides is kneaded together. 4. In addition to the above components (a), (b) and (c), or above (a), (b), (c) and (d).
In addition to the components, or (a), (b), (c),
The method according to any one of claims 1 to 3, wherein (f) an oxidized wax is kneaded together in addition to the components (d) and (e). 5. The organic peroxide (c) is represented by the following formula (1) R—O—O—R ′ (1) (wherein R and R ′ are the same or different and are alkyl. A group, an aryl group or an aralkyl group) or the following formula (2): A method according to claim 1, characterized in that R and R ′ are as defined above. 6. The organic peroxide (C) is dicumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t). -Butylperoxy) hexane or 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-
The method of claim 1, wherein the method is 3. 7. The method according to claim 1, wherein the thermoplastic resin (a) is polyethylene and the kneading is carried out at a temperature of 160 to 220 ° C.