JPH10152602A - Biodegradable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition which has a good moldability and can give a product exhibiting an excellent elongation at break and mechanical properties without any complicated step such as stretching and having a good biodegradability by mixing a saturated aliphatic polyester having a melt viscosity in a specified range with starch and a polyethylene glycol having a number- average molecular weight in a specified range. SOLUTION: A saturated aliphatic polyester (a) having a melt viscosity of 1,000-15,000P at 200 deg.C is mixed with starch (b) and a polyethylene glycol (c) having a number-average molecular weight of 100-20,000 in such amounts that the ratio of component (a) to component (b) is 95/5 to 60/40 by weight, and 1-200 pts.wt. component (b) is present per 100 pts.wt. total of components (a) and (c). It is desirable that the saturated aliphatic polyester is one having a linear structure, because it can give a biodegradable resin composition having a higher rate of biodegradation. With a view to the inhibition of hydrolysis during melt kneading, the starch is desirably one in the form of a powder having a mean particle diameter of 50μm or below and predried at 150 deg.C for about 5hr to a water content of 1wt.% or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable resin composition having excellent elongation at break and biodegradability, which is suitably used for a wide range of uses such as films and containers.

[0002]

2. Description of the Related Art In recent years, with the increasing social demands for environmental protection, biodegradable resins that can be decomposed by microorganisms and the like have attracted attention. Specific examples of the biodegradable resin include polyhydroxybutyrate, polycaprolactone,
Examples thereof include melt-moldable aliphatic polyesters such as polylactic acid and polybutylene succinate.

However, among the above-mentioned conventional aliphatic polyesters, a biodegradable resin capable of producing microorganisms, for example, polyhydroxybutyrate, is extremely expensive, and a biodegradable resin obtained by a chemical synthesis method, such as, for example, Polycaprolactone, polylactic acid, polybutylene succinate, etc. are also two to three times as expensive as general-purpose resins such as olefin-based resins, and these cost issues reduce the versatility of biodegradable resins. That is the current situation.

[0004] In order to cope with the cost problem of the biodegradable resin, a low-cost biodegradable resin composition is prepared by mixing an inexpensive organic or inorganic extender with the biodegradable resin. Is being considered.

Among the above-mentioned organic extenders, attempts have been made to use starches having an effect of increasing the rate of biodegradability together with a biodegradable resin as a biodegradability accelerator. In addition, since the biodegradable resin and the starches have poor compatibility, there is a problem that the resulting biodegradable resin composition is inferior in moldability and physical properties.

As one example of a biodegradable resin composition using the above starches, Japanese Patent Application Laid-Open No. 7-70367 discloses "at least one thermoplastic resin characterized by containing at least one hydroxycarboxylate. Biodegradable molding compositions comprising starch and at least one thermoplastic aliphatic polyester "have been proposed.

However, the biodegradable resin composition proposed above uses a thermoplastic starch, that is, a gelatinized starch. Therefore, when gelatinized with water, a molded product obtained by hydrolysis of polyester during molding is not used. There is a problem that physical properties tend to deteriorate, aging, and the like, and when gelatinizing with a softening agent such as glycerin, the softening agent tends to bleed out to the surface of the molded product, which is not practical.

As another example of a biodegradable resin composition using starch in combination, Japanese Patent Application Laid-Open No. 7-330954 describes
[A] (1) a polyhydric alcohol component (excluding the following polyethylene glycol), (2) a polybasic acid (or anhydride thereof) component, and (3) a polyethylene glycol having a number average molecular weight of 300 or more, 0.1 to 30 parts by weight is added to 100 parts by weight of the total amount of the components (1) and (2), and polycondensation is performed.
For 100 parts by weight of aliphatic polyester at 0 ° C. or higher,
[B] A biodegradable aliphatic polyester composition comprising 1 to 300 parts by weight of starch ”has been proposed.

[0009] However, the biodegradable resin composition proposed above has a problem that, although the compatibility between the polyester resin and the starch is improved, the elongation at break is insufficient when used as a film.

As described above, a biodegradable resin composition having excellent flexibility, good moldability and biodegradability and suitably used for a wide range of applications such as films and containers has not been put to practical use. Is the current situation.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention exhibits excellent elongation at break and mechanical strength without going through complicated steps such as stretching. An object of the present invention is to provide a biodegradable resin composition having excellent moldability and biodegradability and suitably used for a wide range of applications.

[0012]

Means for Solving the Problems The biodegradable resin composition according to the invention of claim 1 (hereinafter referred to as "first invention") comprises the following components (a), (b) and (c): Are mixed. Component (a): a melt viscosity at 200 ° C. of 1000 to 1
50,000 poise saturated aliphatic polyester (b) component: starch (c) component: polyethylene glycol having a number average molecular weight of 100 to 20,000

The invention according to claim 2 (hereinafter referred to as "the second invention")
The biodegradable resin composition according to the first aspect of the present invention, the component (a) and the component (c)
The mixing ratio of the components is 95/5 to 60/40 by weight, and 1 to 200 parts by weight of the component (b) is contained with respect to 100 parts by weight of the total amount of the components (a) and (c). It is characterized by having.

The biodegradable resin composition according to the invention described in claim 3 (hereinafter referred to as "third invention") comprises the following (a)
Component (b), component (c) and component (d) are mixed and reacted. Component (a): a melt viscosity at 200 ° C. of 1000 to 1
(B) Component: Starch (c) Component: Polyethylene glycol having a number average molecular weight of 100 to 20,000 (d) Component: Polyfunctional isocyanate compound

The invention according to claim 4 (hereinafter referred to as the "fourth invention")
The biodegradable resin composition according to the third aspect of the present invention, the component (a) and the component (c)
The mixing ratio of the components is 95/5 to 60/40 by weight, and 1 to 200 parts by weight of the component (b) and (d) based on 100 parts by weight of the total amount of the components (a) and (c). ) Component is characterized by containing 0.5 to 25 parts by weight.

Further, the biodegradable resin composition according to the invention described in claim 5 (hereinafter referred to as “fifth invention”) is the same as the biodegradable resin composition according to any one of the first to fourth inventions. , Wherein the saturated aliphatic polyester is polycaprolactone.

The biodegradable resin composition according to the first invention comprises:
(A) a saturated aliphatic polyester having a melt viscosity at 200 ° C. of 1,000 to 150,000 poises used as the component (a), a starch used as the component (b), and
(C) The number average molecular weight used as the component is 100 to 2
0000 polyethylene glycol.

The saturated aliphatic polyester used as the component (a) in the biodegradable resin composition according to the first invention is a polyester synthesized using only a monomer containing no double bond or aromatic ring. When a polyester containing a double bond or an aromatic ring in the structure is used, the main chain or the aromatic ring remains without being biodegraded, and thus the possibility of adversely affecting the environment increases.

The structure of the saturated aliphatic polyester is not particularly limited, but a saturated aliphatic polyester having a linear structure is more suitable for a biodegradable resin composition having a higher biodegradation rate. It is preferred because it gives.

The method for synthesizing the saturated aliphatic polyester is not particularly limited. Examples thereof include condensation polymerization of a polyhydric alcohol and a saturated aliphatic dicarboxylic acid, polymerization of a hydroxyl group-containing saturated aliphatic carboxylic acid, and caprolactone. And a conventionally known method such as ring-opening polymerization.

The polyhydric alcohol is not particularly restricted but includes ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, butylene glycol, polybutylene glycol, butanediol 1,4, Hexanediol 1, 6 and the like can be mentioned, and one or more of these are suitably used. Further, as the saturated aliphatic dicarboxylic acid,
Although not particularly limited, adipic acid, succinic acid,
Succinic anhydride and the like are mentioned, and one or more of these are preferably used.

Specific examples of the saturated aliphatic polyester are not particularly limited, but include polyethylene adipate, polypropylene adipate, polybutylene adipate, polyhexyl adipate, polyethylene succinate, polybutylene succinate, polybutylene succinate. Adipate, polycaprolactone and the like are mentioned, and one or more of these are suitably used.

In the first invention, the saturated aliphatic polyester as the component (a) needs to have a melt viscosity at 200 ° C. of 1,000 to 150,000 poise. In addition, the melt viscosity mentioned here is a melt viscosity measured by the following method. [Measurement method of melt viscosity] Measuring device : Parallel disk type rheometer RMS (manufactured by Toyo Seiki Co., Ltd.) Measuring conditions : temperature 200 ° C., strain 20%, vibration frequency 1ra
d / sec

If the saturated aliphatic polyester as the component (a) has a melt viscosity at 200 ° C. of less than 1,000 poise, the mechanical strength of the resulting biodegradable resin composition becomes insufficient. When it exceeds, the fluidity of the obtained biodegradable resin composition at the time of heating and melting becomes poor, and the moldability decreases.

The starch used as the component (b) in the biodegradable resin composition according to the first invention is not particularly limited, but may be corn, wheat, potato,
Raw starch obtained from rice, tapioca, sweet potato, etc., physically modified starch such as α-starch, oxidized starch, esterified starch,
Chemically modified starches such as etherified starch and cross-linked starch, and enzyme-modified starches such as dextrin and amylose are preferred, and one or more of these are preferably used.

The shape of the above-mentioned starch is not particularly limited, and may be any of powder, tuber, granule and the like. In order to prevent hydrolysis during kneading, a powdered starch having an average particle size of 50 μm or less,
It is preferable to use a material which has been dried in advance at about 0 ° C. for about 5 hours to a water content of 1% by weight or less.

The polyethylene glycol used as the component (c) in the biodegradable resin composition according to the first invention has a number average molecular weight of 100 to 20,000 (preferably 2).
(00 to 10,000, more preferably 400 to 3000)
It is necessary to be. In addition, the number average molecular weight mentioned here is a number average molecular weight measured by the following method. [Method of measuring number average molecular weight] Measuring apparatus : Showa Denko column "shodex K-8"
GPC measurement by "02, K-803, K-804" Measurement conditions : mobile phase chloroform, flow rate 1 ml / min

If the number average molecular weight of the above polyethylene glycol is less than 100, the mechanical strength of the resulting biodegradable resin composition becomes insufficient, while if it exceeds 20,000, the dispersion of the starch (b) is dispersible. And the elongation at break of the resulting biodegradable resin composition becomes insufficient.

Next, the biodegradable resin composition according to the second invention is the same as the biodegradable resin composition according to the first invention described above, except that the melt viscosity at 200 ° C. as component (a) is 1%.
A saturated aliphatic polyester having a molecular weight of 000 to 150,000 poise and a number average molecular weight of 100 to 20 as the component (c);
The mixing ratio of polyethylene glycol having a weight ratio of 95/5 to 60/40 (preferably 93/7 to 70/70)
/ 30, more preferably 92/8 to 75/25, most preferably 90/10 to 80/20), and based on 100 parts by weight of the total amount of the components (a) and (c).
It is necessary that (b) 1 to 200 parts by weight of starch (preferably 20 to 180 parts by weight, more preferably 30 to 150 parts by weight, and most preferably 50 to 120 parts by weight) is contained.

When the mixing ratio of the above components (a) and (c) exceeds 95/5 by weight, the biodegradable resin composition obtained has insufficient elongation at break, and conversely less than 60/40. If it is, the mechanical strength of the obtained biodegradable resin composition becomes insufficient, or the surface of the finally obtained molded article becomes tacky, which is not preferable.

If the content of the component (b) is less than 1 part by weight based on 100 parts by weight of the total of the components (a) and (c), the product obtained by incorporating the component (b) is obtained. When the biodegradability promoting effect of the degradable resin composition becomes insufficient, and when the content exceeds 200 parts by weight, the melt viscosity of the obtained biodegradable resin composition becomes too high, and is formed into a thin film or the like. Or the elongation at break of the molded article finally obtained becomes insufficient, so that the use of the biodegradable resin composition is restricted.

Next, the biodegradable resin composition according to the third invention comprises a saturated aliphatic polyester having a melt viscosity at 200 ° C. of 1,000 to 150,000 poise, which is used as the component (a), and a starch used as the component (b). ,
(C) The number average molecular weight used as the component is 100 to 2
Polyethylene glycol which is 0000, and (d)
It is composed of a polyfunctional isocyanate compound used as a component.

The components (a), (b) and (c) are the same as those used in the biodegradable resin composition according to the first aspect of the present invention, respectively.
It is suitably used for the same reason as in the case of the biodegradable resin composition according to the first invention.

The polyfunctional isocyanate compound used as the component (d) in the biodegradable resin composition according to the third invention is not particularly limited, but hexamethylene diisocyanate, 2,2,4-trimethyl Aliphatic diisocyanates such as hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate Mixed isocyanate of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 4,
Aromatic diisocyanates such as 4'-diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, diphenylmethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, trimethylol propane and toluylene diisocyanate Triisocyanates such as adducts with isocyanates, adducts of trimethylolpropane and 1,6-hexamethylene diisocyanate, and the like, and one or more of these are preferably used, and among them, diisocyanates One or more of these are more preferably used.

Among the above-mentioned polyfunctional isocyanate compounds, when emphasis is placed on improving the elongation at break of the biodegradable resin composition, an electron-withdrawing aromatic ring having a structure adjacent to an isocyanate group is 4,4 ′. -Aromatic diisocyanates such as diphenylmethane diisocyanate are more preferably used, and when emphasis is placed on improving the biodegradability of the biodegradable resin composition, hexamethylene diisocyanate containing no aromatic ring in the molecular chain can be used. Such aliphatic diisocyanates are more preferably used. Further, when importance is attached to the appearance of the molded article, it is preferable to use aliphatic diisocyanates rather than aromatic diisocyanates containing an aromatic ring having a high possibility of being quinoidized in the atmosphere and yellowing the molded article surface. .

The isocyanate group in the above polyfunctional isocyanate compound may be the component (a) and / or (c)
The biodegradation obtained by reacting with the hydroxyl group in the component to cause the chain extension of the component (a) and / or the component (c) itself and the co-chain extension of the component (a) and the component (c). It significantly improves the elongation at break of the conductive resin composition.

Next, the biodegradable resin composition according to the fourth invention is the same as the biodegradable resin composition according to the third invention,
The melt viscosity at 200 ° C. as the component (a) is 100.
A saturated aliphatic polyester having 0 to 150,000 poise and a number average molecular weight of 100 to 2,000 as the component (c);
The mixing ratio of polyethylene glycol, which is 0, is 95/5 to 60/40 by weight (preferably 93/7 to 70/3).
0, more preferably 92/8 to 75/25, most preferably 90/10 to 80/20), and based on 100 parts by weight of the total amount of the components (a) and (c).
(B) 1 to 200 parts by weight of starch (preferably 20 to 180 parts by weight, more preferably 30 to 150 parts by weight, and most preferably 50 to 120 parts by weight) as the component, and the above (a) Total amount of component and component (c) 10
It is necessary that 0.5 to 25 parts by weight (preferably 1 to 20 parts by weight, more preferably 3 to 15 parts by weight) of the polyfunctional isocyanate compound as the component (d) is contained with respect to 0 parts by weight. is there.

The mixing ratio of the component (a) and the component (c) is specified to be in the range of 95/5 to 60/40 by weight, which is the reason why the biodegradable resin composition according to the second invention described above is used. For similar reasons.

The content of the component (b) is 1 to 200 parts by weight based on 100 parts by weight of the total of the components (a) and (c).
The reason why the amount is specified in the range of parts by weight is the same as in the case of the biodegradable resin composition according to the second invention described above.

In the biodegradable resin composition according to the fourth invention, the content of the polyfunctional isocyanate compound as the component (d) is 0.5% by weight based on 100 parts by weight of the total of the components (a) and (c). If it is less than 10 parts, the effect of improving the elongation at break due to the chain extension of the component (a) and / or the component (c) itself or the co-chain extension of the component (a) and the component (c) cannot be sufficiently obtained. If it exceeds 25 parts by weight, an excess of isocyanate groups causes cross-linking between molecules, causing an increase in the gel fraction, and lowering the elongation at break and moldability of the biodegradable resin composition.

Next, the biodegradable resin composition according to the fifth invention is the same as the biodegradable resin composition according to any one of the first to fourth inventions described above, except that the component (a) is a saturated aliphatic polyester. Use polycaprolactone.

The polycaprolactone is obtained by subjecting caprolactone to ring-opening polymerization in a conventional manner. Its melt viscosity at 200 ° C. is as described in the description of the biodegradable resin composition according to the first invention. For similar reasons, 1
It needs to be between 000 and 150,000 poise.

By using polycaprolactone as the saturated aliphatic polyester as the component (a), a biodegradable resin composition having more excellent breaking elongation and biodegradability can be obtained.

The biodegradable resin compositions according to the first to fifth aspects of the present invention may contain various additives such as extenders, coloring agents, reinforcing agents, waxes, etc., as needed, as long as the achievement of the object of the present invention is not hindered. One or more of the agents may be contained.

Specific examples of the extender include, but are not particularly limited to, talc, calcium carbonate, magnesium carbonate, barium carbonate, magnesium hydroxide, aluminum hydroxide, magnesium oxide, aluminum oxide, diatomaceous earth, and feldspar powder. , Mica, clay, silica, alumina, glass powder, inorganic powder such as stainless steel, aluminum, copper, magnetic iron and wood powder, cellulose, chitin, chitosan,
Organic powders such as collagen, keratin, fibroin and the like can be mentioned, and one or more of these are suitably used.

The method for producing the biodegradable resin composition according to the first to fifth aspects of the present invention is not particularly limited, and each of the essential components (a), (b) and (c) may be prepared in a predetermined amount ( First and second inventions) or predetermined amounts of the essential components (a), (b), (c) and (d) (third and fourth inventions) and as required. Using a known mixing device such as a single screw extruder, a twin screw extruder, a Banbury mixer, a kneading roll, a Brabender, a plastograph, and a kneader, the respective predetermined amounts of various additives to be contained at about 100 to 300 ° C. May be mixed at a temperature of about 3 to 15 minutes by an ordinary method.

In the above manufacturing method, the third invention and the fourth invention
In the case of the invention, the component (d) may be added and mixed after previously mixing the component (a), the component (b) and the component (c),
These four components may be mixed simultaneously.

The biodegradable resin compositions according to the first to fifth aspects of the present invention can be used in an unstretched state after molding, or subjected to a stretching treatment such as uniaxial stretching or biaxial stretching. Of course, it can be used in a state.

[0049]

The biodegradable resin composition according to the first invention has excellent biodegradability due to a saturated aliphatic polyester having a specific melt viscosity and starch, and has a specific number average molecular weight with high fluidity. The dispersibility and adhesiveness of the above two components are improved by the presence of polyethylene glycol, so that good elongation at break and mechanical strength are exhibited.

Further, the biodegradable resin composition according to the second invention is the same as the biodegradable resin composition according to the first invention,
A specific amount of starch is mixed with respect to 100 parts by weight of the total amount of the saturated aliphatic polyester and the polyethylene glycol mixed at a specific mixing ratio, so that more excellent elongation at break and mechanical strength are exhibited. In addition, it has better biodegradability and moldability.

The biodegradable resin composition according to the third invention has excellent biodegradability due to a saturated aliphatic polyester having a specific melt viscosity and starch, and has a high fluidity and a specific number average molecular weight. The dispersibility and adhesion of the two components are improved by the presence of polyethylene glycol, so that not only a good elongation at break and mechanical strength are exhibited, but also the saturated aliphatic polyester and / or Since the polyethylene glycol is chain-extended and / or co-chain-extended, the elongation at break and the mechanical strength are further improved, and the water resistance is also improved.

The biodegradable resin composition according to the fourth invention is the same as the biodegradable resin composition according to the third invention,
A total amount of 100 parts by weight of the saturated aliphatic polyester and the polyethylene glycol mixed at a specific mixing ratio and a specific amount of starch are mixed with a specific amount of a polyfunctional isocyanate compound, and the mixture is reacted. In addition to exhibiting high elongation at break and mechanical strength, it has better biodegradability and moldability.

Further, the biodegradable resin composition according to the fifth invention is the biodegradable resin composition according to any one of the first to fourth inventions, wherein polycaprolactone is used as a saturated aliphatic polyester having a specific melt viscosity. Because of the use of, more excellent breaking elongation and biodegradability are exhibited.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight”, “melt viscosity” means “melt viscosity at 200 ° C.”, and “molecular weight” means “number average molecular weight”.

The components (a) used in Examples and Comparative Examples of the present invention were saturated aliphatic polyesters, the component (b) was starch, the component (c) was polyethylene glycol, and
Component (d): The polyfunctional isocyanate compounds are listed below.

Component ( a): Saturated aliphatic polyester B. Polycaprolactone (melt viscosity: 5000 poise) Polycaprolactone (melt viscosity: 200,000 poise) C.I. Polycaprolactone (melt viscosity: 100 poise) ( b) Component: starch corn starch (average particle size: 30 μm, manufactured by Nippon Shokuhin Kako Co.) ( c) Component: polyethylene glycol i. Molecular weight: 2000, manufactured by Wako Pure Chemical Industries, Ltd. Molecular weight: 400, manufactured by Wako Pure Chemical Industries, Ltd. c. Molecular weight: 40000, manufactured by Wako Pure Chemical Industries, Ltd. ( d) Component: polyfunctional isocyanate compound 4,4′-diphenylmethane diisocyanate (MD
I)

Example 1 ( 1) Production of Biodegradable Resin Composition In a Labo Plastomill ( manufactured by Toyo Seiki Co., Ltd.), 90 parts of polycaprolactone (A) was used as the component (a), and corn starch was used as the component (b). 100 parts and 10 parts of polyethylene glycol (a) were added as the component (c).
The mixture was melt-kneaded for 1 minute to obtain a biodegradable resin composition.

( 2) Preparation of a molded article Using a hydraulic press machine (manufactured by Toyo Seiki Co., Ltd.), the biodegradable resin composition obtained above was molded into a sheet having a thickness of 0.4 mm, and an unstretched sheet was formed. A shaped body was obtained.

( 3) Evaluation The performance (elongation at break, modulus of elasticity,
The degree of biodegradation was evaluated by the following method. Table 1 shows the results.
Was as shown in FIG. The evaluation was performed in a constant temperature and humidity room at 23 ° C. and 65% RH unless otherwise specified.

A sample for measurement was prepared by punching out a sheet-shaped molded body (0.4 mm thick) having a breaking elongation and an elastic modulus . Then, Tensilon (O
Using a tensile speed of 200 mm /
The elongation at break (%) and the modulus of elasticity (kg / mm ² ) were determined in minutes.

[0061] biodegradability 5mm square about the smaller shredded sheet materials (0.
4 mm thick) was cooled to below the glass transition temperature of the molded article by pouring it into liquid nitrogen, and then pulverized together with several pieces of dry ice using a personal mill SCM-40A pulverizer (manufactured by SIBATA). A powder for measurement of 0.8 mm was prepared.

Based on JIS K-6950 "Test method for aerobic biodegradation using plastic-activated sludge", a coulometer OM3001A type (manufactured by Okura Electric Co., Ltd.) was used as a biodegradability evaluation apparatus, and activated sludge A was used as activated sludge. Then, a biodegradation test of the obtained powder is performed, and by the following equation,
The degree of biodegradation (%) after 28 days was determined. D _B = [(SB) / ThOD] × 100 D _B : Degree of biodegradation (%) of plastic or control substance after 28 days S: BOD value of culture medium for biological test or culture medium for control substance after 28 days (Mg) B: BOD value of the culture medium for biological blank test (mg) ThOD: Calculated value of oxygen consumption required for complete oxidation of plastic or control substance (theoretical oxygen demand,
mg)

(Examples 2 to 9, and Comparative Examples 1 to 4) Twelve kinds of biodegradable resin compositions were produced in the same manner as in Example 1 with the composition shown in Table 1. Then, the obtained 1
Using two types of biodegradable resin compositions, molded articles were produced in the same manner as in Example 1 to obtain 10 types of unstretched sheet-shaped molded articles (0.4 mm thick). Comparative Examples 3 and 4
The biodegradable resin composition was difficult to mold, and an unstretched sheet-like molded product could not be obtained.

The performance of the ten types of molded products obtained above was evaluated in the same manner as in Example 1. The results were as shown in Table 1.

[0065]

[Table 1]

Example 10 In a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.), 90 parts of polycaprolactone (A) was used as the component (a), and corn starch 100 was used as the component (b).
Part and polyethylene glycol (a) as component (c)
After adding 10 parts and melting and kneading at 180 ° C. for 2 minutes,
(D) 3 parts of 4,4'-diphenylmethane diisocyanate (MDI) is added as a component,
After kneading for minutes, a biodegradable resin composition was obtained.

Next, an unstretched sheet-shaped molded product (0.4 mm thick) was prepared in the same manner as in Example 1 using the obtained biodegradable resin composition, and the performance of the obtained molded product was measured. Evaluation was performed in the same manner as in Example 1. The results were as shown in Table 2.

(Examples 11 to 18 and Comparative Examples 5 to 5)
8) With the composition shown in Table 2, in the same manner as in Example 10,
Twelve biodegradable resin compositions were produced. Next, using the obtained 12 kinds of biodegradable resin compositions, Example 1 was used.
In the same manner as in the above, molded articles were produced, and 11 types of unstretched sheet-shaped molded articles (0.4 mm thick) were obtained. The biodegradable resin composition of Comparative Example 7 was difficult to mold, and an unstretched sheet-like molded product could not be obtained.

The performance of the 11 types of molded articles obtained above was evaluated in the same manner as in Example 1. The results were as shown in Table 2.

[0070]

[Table 2]

[0071]

As described above, the biodegradable resin compositions according to the first to fifth aspects exhibit excellent elongation at break and mechanical strength without going through complicated steps such as stretching. As well as having good moldability and biodegradability, it is suitably used for a wide range of applications such as films and containers.

Claims (5)

[Claims] 1. The following components (a), (b) and (c)
A biodegradable resin composition comprising a mixture of components. Component (a): a melt viscosity at 200 ° C. of 1000 to 1
50,000 poise saturated aliphatic polyester (b) component: starch (c) component: polyethylene glycol having a number average molecular weight of 100 to 20,000 2. The mixing ratio of the component (a) and the component (c) is from 95/5 to 60/40 by weight, and based on 100 parts by weight of the total amount of the components (a) and (c). 2. The biodegradable resin composition according to claim 1, comprising 1 to 200 parts by weight of component (b). 3. A biodegradable resin composition obtained by mixing and reacting the following components (a), (b), (c) and (d). Component (a): a melt viscosity at 200 ° C. of 1000 to 1
(B) Component: Starch (c) Component: Polyethylene glycol having a number average molecular weight of 100 to 20,000 (d) Component: Polyfunctional isocyanate compound 4. The mixing ratio of the component (a) to the component (c) is from 95/5 to 60/40 by weight, and based on 100 parts by weight of the total amount of the components (a) and (c). 4. The biodegradable resin composition according to claim 3, which comprises 1 to 200 parts by weight of component (b) and 0.5 to 25 parts by weight of component (d). 5. The biodegradable resin composition according to claim 1, wherein the saturated aliphatic polyester is polycaprolactone.