JP3329500B2 - Biodegradable resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable resin composition. More specifically, the present invention relates to a biodegradable resin composition which rapidly decomposes in a biodegradation medium such as soil, garbage or compost.

[0002]

BACKGROUND OF THE INVENTION Japanese Patent Application Laid-Open No. 49-55,740 and corresponding US Pat. No. 4,016,117 disclose biological materials containing starch granules 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 a resin having at least one double bond in one molecule. Biodegradable compositions containing saturated fatty acids or derivatives thereof are disclosed.

Japanese Patent Publication No. 60-41,089 discloses starch particles which are made hydrophobic by reacting the surface of the starch particles with a compound which easily reacts with hydroxyl groups to form an ether or ester, and a synthetic resin. A biodegradable composition is disclosed.

Further, Japanese Patent Publication No. 56-44,907 discloses straight-chain higher alcohols, higher alcohols having straight-chain higher fatty acid methyl branches, higher fatty acids having methyl branches, esters thereof, and di-esters of straight-chain higher fatty acids. -And tri-glycerides, di- of higher fatty acids having methyl branches
And at least one organic substance and an inorganic substance selected from the group consisting of: and tri-glyceride, wherein 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.

[0006] The publication discloses that when a JIS mold resistance test is performed after irradiating the above polyolefin composition with ultraviolet rays, a certain composition range, that is, myristyl myristate 2 to 2, is obtained.
The fact that the strength degradation is dramatically accelerated by a polyethylene composition containing 10% and calcium carbonate of 30 to 40%, and that the resin material is easily decomposed rapidly when the resin material is dumped outdoors. Is described.

Also, Professor Osawa of the Department of Materials Engineering, Faculty of Engineering, Gunma University prepared a composition comprising 10% corn starch in an ethylene / carbon monoxide copolymer and a composition comprising 70% paper in the copolymer. Then, these are exposed to ultraviolet light for 24 hours with a high-pressure mercury lamp or exposed outdoors, and then buried indoors and outdoors to measure the weight loss rate, which is almost twice that of the ethylene / carbon monoxide copolymer alone. (Nippon Kogyo Shimbun, March 1992)
March 9).

[0008] A method for promoting photodegradation of a polymer substance using ultraviolet light is disclosed in Japanese Patent Application Laid-Open No. 61-285,226, which is one of the inventors of the present invention. Is disclosed.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a biodegradable resin composition. Another object of the present invention is to
An object of the present invention is to provide a biodegradable resin composition which can be rapidly decomposed in a biodegradation medium such as soil, garbage or compost. Still other objects and advantages of the present invention will be apparent from the following description.

[0010]

According to the present invention, the above objects and advantages of the present invention include: (a) a thermoplastic resin ;
Polydihydrofuran and (c) starch and / or starch
This is achieved by a biodegradable resin composition characterized by containing a powder modification product . The biodegradable resin composition of the present invention contains the above three components (a), (b) and (c) .

As the thermoplastic resin (a), a general thermoplastic resin is used without any particular limitation. For example, a polyolefin-based 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 other comonomers; 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 resin). Polymeric saponified products); polyurethane resins; polyether resins; rubbers such as natural rubber, isoprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, and mixtures thereof. . Among these, use of a polyolefin resin or the like is preferable.

The polydihydrofuran (b) has the following formula

[0013]

Embedded image

A homopolymer or a copolymer mainly composed of the repeating unit represented by the formula (1) is preferably used. Especially, a homopolymer is preferable. Polydihydrofuran (b)
Has a number average molecular weight of preferably 5,000 to 100,000, more preferably 10,000 to 70,000. Further, the preferred weight average molecular weight is 7500 to 350,000, and the more preferred weight average molecular weight is 15,000 to 25,000.

The polydihydrofuran (b) is used alone or in combination with a monomer having an ethylenically unsaturated double bond capable of cationically polymerizing 2,3-dihydrofuran in the presence of a cationic polymerization catalyst, for example, toluene. It can be produced by cationic polymerization in such a hydrocarbon solvent. Examples of the cationic polymerization catalyst include B
F ₃ , BF ₃ .O (C ₂ H ₅ ) ₂ , C ₂ H ₅ AlCl _{2 and the} like are preferably used. The polymerization temperature is preferably from -78 ° C to 3 ° C.
It is in the range of 0 ° C. Polymer Preprints, Japan, vol. 4
0, No. 8, 2691 to 2693 (1991), when a hot-pressed 100-μm thick film was stored at room temperature for 50 days, the number-average molecular weight was reduced to about 50%. It is stated that the properties have also been reduced. However, despite the presence of polydihydrofuran, the composition of the present invention did not change the tensile strength of the film even after standing at room temperature, for example, for two months.

The polydihydrofuran (b) is preferably used in an amount of 0.05 to 10 per 100 parts by weight of the thermoplastic resin (a).
0 parts by weight, more preferably 0.1 to 50 parts by weight.

The compositions of the present invention may contain Starch or starch modified product of (c) In addition, the necessary, contains an oxide (d) or metal compound (e). Examples of starch or modified starch (c) include rice,
Starch obtained from corn, potato, sweet potato, wheat, or the like; or a starch obtained by grafting a polymerizable monomer such as styrene, coated with silicon, or a sugar such as lactose or glucose; Modified starches, such as those modified as organic substances which are contained as an ingredient and are preferred by living organisms, may be mentioned.

The amount of starch and / or modified starch is preferably 70 parts by weight or less, more preferably 5 to 5 parts by weight, per 100 parts by weight of the total weight of the thermoplastic resin (a) and the polydihydrofuran (b). 70 parts by weight, particularly preferably 7 to 20 parts by weight. Biodegradability increases as the amount of starch and / or modified starch increases. However, when the amount exceeds 70 parts by weight, the physical properties of the resin tend to be significantly reduced, which is not practical.

Examples of the oxidized oil (d) include those obtained by oxidizing animal oil and vegetable oil. Preferably, vegetable oils are oxidized by boiling or the like. The time for the boiling treatment is not particularly limited, but the treatment is preferably performed for 5 hours or more. Preferred vegetable oils 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 the biodegradability is promoted. The amount of the oxidized oil is preferably 10 parts by weight or less, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the thermoplastic resin (a).
Parts by weight, particularly preferably from 0.3 to 5 parts by weight. The biodegradability increases as the amount of the oxidized oil increases. However, when the amount exceeds 10 parts by weight, the physical properties of the resin tend to be significantly reduced, which is not practical.

The metal compound (e) includes, 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;
Metal oxides or metal hydroxides are preferably used.
As the metal salt, an inorganic acid salt or an organic carboxylate is preferable. As the organic carboxylate, a higher aliphatic carboxylate is particularly preferred. As the inorganic acid, for example, 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 metal,
Iron, aluminum and the like are particularly preferred. These metal compounds may be used alone or in combination of two or more. In particular, when a metal salt of an inorganic acid and a metal salt of a higher aliphatic carboxylic acid are used in combination, the biodegradability is significantly improved.

The amount of the metal compound is 30 parts by weight or less, more preferably 0.1 to 30 parts by weight, particularly preferably 0.3 to 1 part by weight, per 100 parts by weight of the thermoplastic resin (a).
0 parts by weight. The biodegradability increases as the amount of the metal compound increases. However, if the amount exceeds 30 parts by weight, the physical properties of the resin tend to be significantly reduced, which is not practical.

The above-mentioned biodegradable resin composition of the present invention can be prepared by the above-mentioned kneading apparatus using a conventional kneading apparatus such as an open-type mixing roll, a non-open-type Banbury mixer, a kneader, a single-screw extruder, or a twin-screw extruder. It can be obtained by kneading at least one of the components (a) and (b) and, if necessary, the components (c), (d) and (e).

The biodegradable resin composition of the present invention can be used for packaging materials such as films, sheets, tapes, yarns, strings, nets, etc., industrial materials such as civil engineering and fisheries, shopping bags, garbage bags, and light-weight packaging bags. It can be formed into various forms such as diaper film, agricultural multi-film, soft drink carrier, sandbag, curing sheet, vegetation net, food container, tableware, bucket and other containers, toys, medical equipment, etc. . These molded articles can be produced by various molding methods such as masterbatch, extrusion molding, injection molding, inflation molding, calendar molding, blow molding, and rotational molding.

[0024] The biodegradable resin composition of the present invention includes rubbers, plasticizers, lubricants, ultraviolet absorbers, other antioxidants, foaming agents, cross-linking agents, without departing from the scope of the present invention.
Additives such as antistatic agents, anti-violent agents, flame retardants, colorants, and fillers can be included.

The resin composition of the present invention does not show any remarkable deterioration in properties under normal use conditions. However, when it is discarded after use and left in contact with a biodegradation medium such as soil, raw rubber or compost, it is characterized in that it decomposes at a much higher rate than ordinary resins.

The resin composition of the present invention can be brought into contact with a biodegradable medium as it is for decomposition, or it can be brought into contact with the biodegradable medium after irradiation with ultraviolet rays.

The soil, garbage and compost can be used alone or mixed together. It is advantageous to place the resin composition of the present invention and the biodegradable medium in as close contact as possible. For example, when the resin composition is in the form of a film, it is desirable that both sides of the film come into contact with the biodegradable medium while the film is stretched well. Upon contact with the biodegradable medium, the biodegradability of the resin composition is promoted by microorganisms present in the medium. The contact temperature with the biodegradable medium is preferably about 0 to 40C.

Irradiation with ultraviolet light is performed, for example, by irradiating ultraviolet light having a maximum intensity emission line in a wavelength region of 400 nm or less, or having a continuous spectrum peak (hereinafter referred to as first ultraviolet light), or in a wavelength region exceeding 400 nm. After irradiating an ultraviolet ray having a bright line of the maximum intensity or a peak of a continuous spectrum (hereinafter referred to as a second ultraviolet ray) with the above ultraviolet ray, the water content is at least 0.03.
This is advantageously performed by further irradiation under an atmosphere of 4 g / l. In particular, the latter irradiation method is preferred.

The first ultraviolet ray is, for example, a low-pressure mercury lamp,
Dutorium lamps and metal halide lamps can be obtained as light sources. As the low-pressure mercury lamp, a lamp whose mercury vapor pressure is usually about 50 mmHg or less is preferably used. Low pressure mercury lamps are 184 nm and 253.
Light having a strong emission spectrum at 7 nm (maximum) is given. Irradiation of the first ultraviolet ray is performed in an ordinary atmosphere,
It can be carried out at a temperature of ８０80 ° C. and a relative humidity of 0-100%.

The irradiation time of the ultraviolet rays differs depending on the irradiation dose. The irradiation dose is the surface area 1c of the biodegradable resin composition.
The emission line or peak at a wavelength of 250 nm per m ² is about 30 to
Preferably a dose of 100 milliwatts, about 35
More preferably, it is ~ 55 milliwatts. The dose rate of the first ultraviolet ray is about 2.1 to 1.3 per cm 2 of the resin composition.
Preferably it is 3 watts / min. The first ultraviolet light is applied to the resin composition at the above dose, for example, from about 10 to about 120.
Irradiation for minutes. The first ultraviolet light source can be located at a distance of usually about 100 cm or less from the resin composition. Operationally, this distance is about 20-50c
m is preferable.

The second ultraviolet ray, that is, an ultraviolet ray having a higher wavelength, can be obtained, for example, from a high-pressure to ultra-high-pressure mercury lamp, a xenon lamp, a helium cadmium laser, or a xenon flash lamp as a light source. Among these light sources, a high-pressure or ultra-high-pressure mercury lamp is particularly preferably used. As the high-pressure to ultra-high-pressure mercury lamp, a lamp in which the mercury vapor pressure of the normally enclosed mercury is 1 to 20 atm.ab. is preferably used. High pressure mercury lamp is 365nm,
It gives light with a strong emission spectrum at 404 nm, 546 nm and 577 nm. 546 nm and 577 n
The m emission line is the strongest.

The irradiation of the second ultraviolet ray may be performed in an atmosphere having a water content of at least 0.034 g / l, for example, an atmosphere having a relative humidity of at least 67% at 40 ° C.
It is preferably carried out in an atmosphere having a water content of at least 0.038 g / l. The second ultraviolet ray may have a dose of about 0.5 to 4 watts as a bright line or peak at a wavelength of 420 nm per cm ² of the surface area of the resin composition. The dose is preferably about 1-2 watts on a 420 nm wavelength emission line or peak on the same basis.

The dose rate of the second ultraviolet ray is determined based on the resin composition 1
Approximately 30 emission lines or peaks at a wavelength of 420 nm per cm ²
Preferably it is ~ 240 watts / min. The second ultraviolet light is applied to the resin composition at the above dose, for example, about 10 to
Irradiation can be for about 100 minutes. The second ultraviolet light source can be located at a distance of about 100 cm or less from the resin composition. Operationally, this distance is preferably between about 20 and about 50 cm.

In the irradiation with ultraviolet light, it is preferable to perform the ultraviolet irradiation until the oxidation start temperature of the biodegradable resin composition decreases by at least 5 ° C., more preferably, until the oxidation start temperature decreases by at least 8 ° C. Preferably, the oxidation is advantageously performed until the temperature at which the oxidation starts decreases by at least 10 ° C.

When the resin composition of the present invention was brought into contact with a biodegradable medium, it became clear that the following occurred. It was confirmed that the amount of carboxylic acids and esters, which are products before entering the β-oxidation by the enzymatic reaction, increased remarkably. Measurement of the molecular weight by GPC confirmed a decrease in the weight average molecular weight. This means that the main chain is cleaved on the polymer side, and it was confirmed that polydihydrofuran or an autoxidizing agent for oxidized oil was effective. Significant starch reduction. It was confirmed that the auto-oxidant did not undergo any runaway oxidation at room temperature, which indicates that the product can be stored for a long time. UV irradiation + garbage burying process causes very fast deterioration. Since the mold-like deposits are particularly conspicuous, the biodegradation can be further expected by continuing the burying treatment for a longer period of time.

[0036]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to only such Examples.

Example 1 (1) In a 300 ml two-necked flask, 2,3-dihydrofuran (dehydrated on anhydrous sodium sulfate, boiling point 54.
21 g of toluene (fraction at 5 to 55 ° C.) and toluene (dehydration over anhydrous sodium sulfate, fraction having a boiling point of 108.5 to 109 ° C.)
Charge 90 ml and dry-ethanol / ethanol bath -7
Cooled to 0 ° C. Then, boron trifluoride ethyl ether complex 0.6 in 10 ml of toluene.
The resulting solution was added dropwise with stirring, and polymerization was carried out for 1 hour. Further, the temperature of the dry ice / ethanol bath was raised, the temperature of the contents in the flask was raised to -60 ° C, and polymerization was carried out for another hour with stirring. Then, it takes 30 minutes to raise the temperature of the contents to room temperature,
Immediately thereafter, the content was dropped into 900 ml of methanol with stirring to reprecipitate the polymer. After filtering off the polymer, the polymer was dried under reduced pressure at room temperature for 70 hours and further dried under reduced pressure at 50 ° C. overnight. The yield of the polymer was 100%.

When the softening temperature of the obtained polymer was subjected to TMA (thermomechanical analysis), shrinkage started around 76 ° C., rapid expansion accompanied by foaming was observed at 133 to 145 ° C., and 145 to 145 ° C. It was found that the softening progressed at 160 ° C. In addition, the measurement conditions of TMA are as follows. Measuring machine: TA-3000, TMA-4 manufactured by METTLER COMPANY
0 Measurement temperature: 30 to 160 ° C. Heating rate: 10 ° C./min Load: 0.02 N Atmosphere: 40 ml / min N ₂ On the other hand, according to DSC (differential thermal analysis), an exothermic phenomenon due to decomposition accompanied by foaming from 147 ° C. Was observed.

(2). 62.0 parts by weight of low-density polyethylene (F-31N, manufactured by Nippon Petrochemical Co., Ltd.) and 21.5 parts of starch
Parts by weight, 4.0 parts by weight of calcium oxide, 12 at 300 ° C.
5.0 parts by weight of oxidized rapeseed oil oxidized by boiling for 5.0 hours, 5.0 parts by weight of iron stearate and 2.5 parts by weight of the polydihydrofuran polymer obtained in the above (1) are blended, and a Henschel mixer is used. And mixed by dry blending. This mixture was melt-mixed with an extruder to obtain a high-concentration master batch pellet.

20 parts by weight of the masterbatch pellets were added to low-density polyethylene without additives (manufactured by Nippon Petrochemical Co., Ltd.).
F31N) was mixed with 80 parts by weight and dry-mixed, and then a 50 μm thick film (hereinafter, referred to as film No. 3) was produced by an inflation molding method using an extruder having a screw diameter of 40 mmφ. Test specimens were formed from this film.

The amounts of each component in the test piece are as follows. Low-density polyethylene (F31N) 92.4% by weight Starch 4.3 "Calcium oxide 0.8" Rapeseed oil 1.0 "Polydihydrofuran 0.5" Iron stearate 1.0 "

In the same manner as described above, a film was prepared using low-density polyethylene and masterbatch pellets in the following proportions. Film number Low density polyethylene Masterbatch pellet (parts by weight) (parts by weight) No. 1 100 0 No. 2 90 10 No. 4 70 30 No. 5 60 40

(3) Each of the test pieces of Film Nos. 1 to 5 was buried in garbage and forest soil for about 2 months. The test pieces of Films Nos. 3, 4 and 5 were separately subjected to 250 to 250% in an atmosphere of 90% relative humidity.
A first ultraviolet ray having a peak in a wavelength region of 310 nm is irradiated from a low-pressure mercury lamp for 3 hours, and then is irradiated in the same atmosphere for 60 hours.
A second ultraviolet ray having an emission line at 0 nm is irradiated from a high-pressure mercury lamp to 20
After irradiation for hours, they were also buried in garbage and in forest soil for about 2 months.

Two months later, each test piece was dug out, and each test piece was subjected to appearance observation, observation using an optical microscope, observation using an SEM, tensile test, molecular weight distribution measurement, oxidation initiation temperature measurement, and measurement using a microscope FT-IR. went. The results are shown below.

Appearance observation Tables 1 and 2 below collectively show the results.

[0046]

[Table 1]

[0047]

[Table 2]

Observation by Optical Microscope In all the samples, pores considered to have the starch removed were observed. Also, brown to black deposits were observed near the pores. The edges of the vacancy seemed to be uplifted. In addition, the attachment of hyphae and mold was particularly conspicuous in the No. 5 UV-irradiated sample.

Observation by SEM No. 3 Samples with a diameter of 10
Voids, which are considered to have starch of about μm, were found. In addition, in the sample of No. 3 UV irradiation and garbage burying treatment, a state where the surface contracted and a state where the surface was dissolved were observed. Furthermore, in the sample of No. 5 UV irradiation and forest burial treatment, hyphae-like deposits were observed around the pores, and it appeared that the sample was partially dissolved.

Tensile test The results are shown in Tables 3 and 4 below.

[0051]

[Table 3]

[0052]

[Table 4]

The following can be seen from Table 4. The tensile strength is
All samples have been reduced by the two months of burial treatment. Regarding the No. 3 film, the UV irradiation + garbage burying treatment has a greater effect on the physical properties than the case where the film is buried in garbage as it is. No.
No significant difference was observed in the degree of decrease in tensile strength between the samples No. 4 and No. 5. In addition, in order to confirm that the sample did not change with time, the tensile strength of an unirradiated and untreated No. 4 sample left for 2 months was measured. Since the initial tensile strength was 156 kgf / cm ² and that after standing for 2 months was 154 kgf / cm ² , it was confirmed that there was no change with time due to standing.

Measurement of Molecular Weight Distribution by GPC The molecular weight distribution of the UV irradiated sample of No. 5 film was measured by GPC. Table 5 shows the results.

[0055]

[Table 5]

Although the number average molecular weight does not change, a decrease in the weight average molecular weight after the embedding process is observed. The weight average molecular weight is related to the tensile strength, and a decrease in the weight average molecular weight reflects a decrease in the tensile strength (see Table 4). Also,
The weight average molecular weight reflects the molecular weight of the polymer, but in this case, the molecular weight of the polymer chain is reduced (shift to the lower molecular weight).
Is suggested.

Measurement of Oxidation Onset Temperature The results are shown in Table 6 below.

[0058]

[Table 6]

Table 6 shows the following. In any of the samples of No. 3 and No. 5, a decrease in the oxidation start temperature was recognized by the burying treatment for two months,
It can be seen that the oxidative deterioration is progressing. In the No. 3 film, there is no significant difference in the degree of reduction in the oxidation start temperature due to the burying process, but the UV irradiation + garbage burying process is more advantageous. No. 5 film buried in mountain forest shows the same degree of reduction regardless of the presence or absence of UV treatment. By the UV irradiation, a decrease in the oxidation start temperature is observed for all the samples. The untreated sample left at room temperature (22 ° C.) for 2 months after production had an oxidation onset temperature of 211.3 ° C., which was almost the same as that before standing (211.9 ° C.). It was confirmed that no runaway of the oxidation reaction occurred.

Microscope FT-IR measurement (1) 1710 cm ^-1 : absorption by carboxylic acid generated by oxidative deterioration and decomposition Absorbance at 1710 cm ^-1 (peak height) is shown in Table 7 below.

[0061]

[Table 7]

The following can be seen from Table 7. 1710cm
The peak height near ^-1 shows a large increase in all samples. The sample irradiated with UV showed a larger increase in peak height, and the sample of No. 5 showed the largest increase. Since carboxylic acid is a product before β-oxidation in the process of polyethylene biodegradation, sufficient biodegradation is expected thereafter.

(2). 1745 cm ^-1 : Reduction of oil-derived carbonyl groups and absorption of ester formed by biodegradation The absorbance at 1745 cm ^-1 (peak height) is shown in Table 8 below.

[0064]

[Table 8]

Table 8 shows the following. The peak height near 1745 cm ^-1 is all reduced in the non-irradiated sample, but is increased in any sample irradiated with UV. In the UV-irradiated sample, it is considered that the ester was newly formed by the biodegradation of the film surface after the oil was reduced. In the unirradiated sample, no significant difference was observed in the degree of decrease in the peak height of No. 4 and No. 5, but in No. 5 for two months after the burial, the peak derived from oil decreased once and It seems that the ester formed in the process is increasing. A polymer chain having an ester group added directly to the main chain is very easily decomposed. This is exo from the molecular end
Not only the geneous cleavage, but also the ester group itself
This is because they will be attacked in endogeneous enzyme reactions.

(3). 990 cm ^-1 : absorption of CO by starch The absorbance (peak height) at 990 cm ^-1 is shown in Table 9 below.

[0067]

[Table 9]

Table 9 shows the following. 990cm ^-1
The peak height in the vicinity decreases in any sample regardless of the presence or absence of UV irradiation. Since the degree of reduction in the peak height of the UV-irradiated sample is larger than that of the unirradiated sample, it is considered that the starch is considerably easily removed. This indicates that the biodegradable disintegration can be sufficiently adjusted by adjusting the amount of added starch.

(4). 1720 cm ^-1 : Absorption by ketone generated by biodegradation Absorbance (peak height) at 1720 cm ^-1 is shown in Table 10.

[0070]

[Table 10]

The following can be seen from Table 10. In all samples, a significant increase or production of ketone is observed by the burial treatment. No. 5 sample with UV irradiation showed the largest increase in peak height.

[0072]

According to the present invention, there is provided a biodegradable resin composition which is rapidly decomposed in a biodegradation medium such as soil, garbage or compost.

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Claims (7)

(57) [Claims] A biodegradable resin composition comprising (a) a thermoplastic resin , (b) polydihydrofuran, and (c) starch and / or a modified starch . 2. (d) The claim 1, further containing an oxidizing oil
A biodegradable resin composition. Wherein (e) metal salts, metal oxides and claim 1 or 2 of the biodegradable resin composition further contains a metal compound selected from the group consisting of metal hydroxides. 4. A poly-dihydrofuran and (b), the thermoplastic resin (a) 100 parts by weight of per any of the biodegradable resin composition according to claim 1-3, containing in a proportion of 0.1 to 100 parts by weight object. 5. Starch and / or modified starch (c)
The thermoplastic resin (a) and poly dihydrofuran total weight 100 parts by weight per (b), the biodegradable resin composition of claim 1 containing the following 70 parts by weight. 6. An oxidized oil (d) is added to a thermoplastic resin (a) 1
00 parts by weight per claim 1 containing 10 parts by weight or less or
Or 2) a biodegradable resin composition. 7. A metal compound (e), the thermoplastic resin (a) 100 parts by weight of per any of the biodegradable resin composition according to claim 1 to 3 containing 30 parts by weight or less.