JP2001316578A - Mulching film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aliphatic polyester-based resin composition having high mechanical strength in molding at a high temperature and good malleability in various moldings including blow molding, improved in mechanical characteristics (particularly vertical tear strength) and excellent in biodegradability. SOLUTION: This biodegradable mulching film for agriculture is obtained by molding an aliphatic polyester-based resin composition composed of (a) a dehydration condensing type aliphatic polyester resin and/or (b) polylactone and (c) diatomaceous earth and treated y radiation exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dehydration-condensation type aliphatic polyester resin (a) and / or a polylactone.
(b) and a resin composed of diatomaceous earth (c), a biodegradable agricultural multi-film formed by molding an aliphatic polyester-based resin that has been subjected to radiation treatment and an aliphatic polyester-based resin composition containing the resin. And a method for producing the multi-film. The biodegradable agricultural multi-film,
The mechanical strength during molding and the tear strength after film formation are improved, and the biodegradability is excellent.

[0002]

2. Description of the Related Art Agricultural multi-films or sheets (both are sometimes simply referred to as agricultural multi-films or multi-films hereinafter) are used for controlling a drastic change in soil temperature.
It is used for the purpose of increasing the yield of crops by controlling weed growth and releasing nutrients gradually. Conventionally, this agricultural multi-film is mainly made of polyolefin such as polyethylene, vinyl chloride resin, ethylene-vinyl acetate copolymer resin and other general-purpose ones which are colored black, silver, white or the like. Have been used. These resins are inexpensive and have excellent weather resistance, but have virtually no biodegradability, and thus require recovery after use. However, it is difficult to collect and reuse the dirty film after use.In the case of disposal, incineration and landfill disposal can be mentioned.However, hardly decomposable resins such as polyolefin and polyvinyl chloride are used for incineration. Damage to the incinerator due to the high calorific value and the generation of harmful exhaust gas pose a problem.On the other hand, these are chemically stable and hardly decompose even if they are disposed of or left in the natural world after use. ,
Environmental pollution caused by remaining in the environment forever has become a problem, and its disposal has become a social problem. As a countermeasure for this, various biodegradable resins have been proposed, and alternatives to the above resins have been studied.

[0003] In order to solve this problem, after using for a necessary period as an agricultural multi-film, the strength of the film decreases, it becomes easy to plow into the soil, and the soil is completely decomposed by microorganisms. Multi-films that do not require treatment have been studied, and the use of various biodegradable resins has been proposed. Moreover, this biodegradable resin is unlikely to be biodegradable on the soil surface like other general resins, but is usually brittle by lowering its weather resistance to natural conditions such as temperature, humidity and light. Can occur,
Since the strength of the film after the above-mentioned predetermined use period can be changed relatively freely, it is suitable as an agricultural multi-film. Here, biodegradable resin does not exhibit biodegradability almost in the same way as general-purpose plastics when used as an agricultural multi-film, but after disposal, when buried in activated sludge, soil, compost, etc. Refers to a polymer compound that is rapidly degraded biochemically by microorganisms such as bacteria and molds, and in some cases, to carbon dioxide and water.

As the biodegradable resin used as such an agricultural multi-film, in order to satisfy the above requirements, in addition to a specific polyester biodegradable resin, starch-EVOH (ethylene-vinyl alcohol copolymer) is used. Polymer-based resins, EVOH-based resins-aliphatic polyester-based resins, aliphatic polyester-based resins-polyolefin-based resins, etc., are known as blended resin compositions. When viewed as an agricultural multi-film, when viewed as an agricultural multi-film, the moldability required at the time of film production, the anti-mold properties required for the multi-film, weather resistance and other physical properties, and the raw properties required after disposal An excellent resin or resin composition balanced in all aspects such as chemical degradability has not yet been proposed. In particular, many of them are inferior in mechanical properties as a film, particularly tearability, as compared with general-purpose resins in terms of imparting biodegradability. Conversely, most of those having excellent tearability are inferior in their biodegradability and other physical properties, for example, thermal properties.

[0005] Therefore, natural materials such as biocellulose and starch-based plastics, low-substituted cellulose esters, natural polyesters produced by microorganisms, and aliphatic polyester resins produced by chemical synthesis are used as biodegradable plastics. Etc. are being studied. Among these, aliphatic polyester resins obtained by chemical synthesis are relatively well-balanced in terms of processability, cost, mechanical properties, water resistance, etc., and are attracting attention as easy-to-use resins for various applications. , Polylactone and the like.
Specific examples of the biodegradable resin include aliphatic polyesters such as poly ε-caprolactone, polyhydroxybutyrate / polyhydroxyvalerate copolymer, and polylactic acid.
Modified starch / modified polyvinyl alcohol (PVA) compositions, carbonyl group-containing photodegradable polymers, and the like. Of these, aliphatic polyesters such as polyε-caprolactone, polyhydroxybutyrate / polyhydroxyvalerate copolymer, and polylactic acid have received the most attention because they are completely biodegradable.

For example, Japanese Patent Application Laid-Open No. 8-150658 proposes specific molding conditions for molding using a resin composition comprising a starch-EVOH-polycaprolactone resin. Although the obtained film is somewhat excellent in the tearability described above, it uses EVOH, which is low in biodegradability of the main raw material and is not completely biodegradable, and is not suitable for outdoor use. Since it contains unbearable starch as an essential component, it is not practical as an agricultural multi-film. JP-A-8-188706 discloses that 80 to 100% by weight of poly ε-caprolactone (hereinafter sometimes abbreviated as polycaprolactone, PCL) which is a biodegradable resin,
The lubricant is 0.3 with respect to 100 parts by weight of a mixture with 20 to 0% by weight of a biodegradable linear polyester resin produced by living organisms.
Although a biodegradable plastic film obtained by molding a composition comprising 0.8 to 0.8 parts by weight is disclosed, there is a problem in mechanical strength at the time of film formation, and mass production of the film is difficult. Not only is it difficult, but even if the film is put into a composting device together with garbage, the biochemical decomposition of the film takes 100 days, so the decomposition rate cannot be said to be sufficiently fast.

Japanese Patent Application Laid-Open No. Hei 8-11206 proposes to use a downward die for inflation film formation of a biodegradable resin. Since no solution to the problem based on the properties of the resin itself has been disclosed, it has not been a fundamental solution to the problem in inflation film formation of a biodegradable resin.

The aliphatic polyester resin is represented by a polyester resin obtained by polycondensation of an α, ω-functional aliphatic alcohol and an α, ω-functional aliphatic dicarboxylic acid, but generally has a low melting point. However, it cannot be used as an alternative to conventional polyolefins. However, it is known that certain polyester resins have a melting point of 100 ° C. or higher and have thermoplasticity, and synthesis studies have been conducted. That is, polyester resin obtained from succinic acid and 1,4-butanediol, polyester resin obtained from succinic acid and ethylene glycol, polyester resin obtained from oxalic acid and neopentyl glycol, oxalic acid
Polyester resin obtained from 1,4-butanediol,
Polyester resins obtained from oxalic acid and ethylene glycol correspond to them. Among them, the polyester resin obtained from oxalic acid has particularly poor thermal stability and does not reach a high molecular weight, but the polyester resin obtained from succinic acid has relatively good thermal stability, and synthesis devises have been made. Was. However, even if these succinic aliphatic polyester resins are polycondensed using a general apparatus, it is difficult to obtain a high molecular weight, and it is difficult to obtain a resin having practical mechanical strength.

Further, JP-A-9-235360 and 9-235360
No. 233956 discloses an aliphatic oxycarboxylic acid unit represented by (1) -OR ¹ -CO- (R ¹ is a divalent aliphatic hydrocarbon group), (2) -OR ^2- A diol unit represented by O— (R ² is a divalent aliphatic or alicyclic hydrocarbon group) and an aliphatic dicarboxylic acid unit represented by (3) —OC—R ³ —CO— (R ³ is An agricultural film such as an agricultural multi-film using an aliphatic polyester-based copolymer having a predetermined molecular weight, which is composed of a direct bond or a divalent aliphatic hydrocarbon group, has been proposed. Is not specified, and there is a problem in the supply of raw material resin itself that requires stable film properties, which is also not practical.

Japanese Unexamined Patent Publication (Kokai) No. 7-177826 discloses an agricultural film comprising polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid, and a plasticizer and an ultraviolet absorber, all of which are shown in Examples. As described above, in order to increase the strength, a stretching treatment is required as a post-treatment, which is not preferable as an agricultural film requiring mass productivity and versatility.

On the other hand, a lactone resin such as polycaprolactone is a biodegradable resin and is an environmentally friendly resin. However, there is a limit in the practicality as a multi-film, and it cannot be used immediately as an agricultural multi-film.

Therefore, it has been practiced to increase the molecular weight of the hydroxyl group of the polyester resin by a urethane bond using a polyisocyanate or the like. For example,
No. 9-67513 discloses a polyester resin composition having improved biodegradability obtained by mixing 1 to 200 parts by weight of polycaprolactone with respect to 100 parts by weight of an aliphatic polyester resin having a high molecular weight with an aliphatic isocyanate. Is disclosed. Since the polyisocyanate used here exhibits properties superior in biodegradability to aliphatic ones than aromatic ones,
Hexamethylene diisocyanate and the like are often used. As described above, at present, low-molecular-weight aliphatic polyester resins are made to have a high molecular weight, mechanical properties are secured, and processing such as injection molding, blow molding, fiberization, and film formation is performed.

However, even with these aliphatic polyester resins, when the crystallinity is high, or when a urethane bond is introduced into the resin molecule as described above, the biodegradability by microorganisms usually decreases. This means that biodegradation proceeds from the amorphous portion of the resin, and the crystalline portion is known to be difficult to decompose and to remain easily. The biodegradability of caprolactone-based polyurethane using hexamethylene diisocyanate is JIS
It is clear from the results of the evaluation in the decomposition test in activated sludge specified in K6950 that almost no decomposition was observed. Since such a tendency is also observed in a urethane bond-containing resin having a relatively low density,
The biodegradability is often reduced due to the presence of a small amount of urethane bonds of about several percent by weight, which inherently include a biodegradable polyester resin for increasing the molecular weight. In fact, a number average molecular weight of 40,00 is obtained by connecting 4 to 5 molecular terminal hydroxyl groups of a succinic polyester resin having a number average molecular weight of about 10,000 using polyisocyanate.
JIS K6 polyester resin with high molecular weight from 0 to 50,000
When evaluated in a decomposition test in activated sludge specified in 950, the evaluation result was that it was difficult to decompose, and it was not practical as an agricultural multi-film.

A single aliphatic polyester resin exhibits biodegradability in an environment where bacteria capable of decomposing the aliphatic polyester resin efficiently exist. However, by mixing and kneading polycaprolactone having a better degradability, the kneaded resin is obtained. Due to the fact that there is an increase in the probability that bacteria that decompose are present in the environment, and once decomposition begins, the surface area increases, the surface becomes hydrophilic, and an environment in which bacteria can grow easily is created. Degradability is improved as compared with resin. However,
When vacuum molding, blow molding, inflation molding, or the like is performed using such a resin, there is a problem that the resin melted during the molding is drawn down.

Generally, the biodegradable resin is a crystalline resin, so that its secondary workability is problematic. Therefore, there is a method of blending a resin having a chemically introduced branched structure, or a method of introducing a branched structure by irradiation with radiation. However, in the case of a branched resin, there is a problem that the strength of the resin is insufficient, and in the case of radiation irradiation, a certain amount of irradiation is required. On the other hand, there is a method of improving apparent suitability by blending talc or the like in order to improve processability such as extrusion. In this case, it is effective for a certain range of processing, but is essentially improved. Since it is not a material, processing a thin material does not solve the problem.

Japanese Patent Application Laid-Open No. H11-140291 describes a polyester resin in which polycaprolactone is blended with another aliphatic polyester to improve biodegradability and moldability. In this case, the tear strength was extremely lower than that of a general-purpose resin, and the tear strength was not always sufficient as an agricultural multi-film.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide biodegradability, moldability, and mechanical properties using a dehydrated aliphatic polyester resin (hereinafter, sometimes abbreviated as aliphatic polyester resin) and / or polylactone. Excellent biodegradability by molding a resin composition having excellent properties, mechanical strength at the time of molding, mechanical properties (particularly tear strength) improved biodegradable agricultural multi-film, and the biodegradable agriculture To provide a method for producing a multi-film for use.

[0018]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone
Aliphatic polyester resin composition obtained by irradiating the composition comprising (b) and diatomaceous earth (c),
High melt tension during high temperature molding, improved strain hardening,
It has been found that it can be applied to various moldings such as blow molding without any trouble and has excellent biodegradability, and that the above-mentioned problems can be solved by molding the resin, and the present invention has been completed.

That is, a first aspect of the present invention is a resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or a polylactone (b) and diatomaceous earth (c), wherein the fat is irradiated with radiation. The present invention relates to a biodegradable agricultural multi-film formed by molding an aromatic polyester resin composition. A second aspect of the present invention is that the polylactone (b) is ε-caprolactone, 4-methylcaprolactone, 3,5,5-trimethylcaprolactone, 3,3,5-trimethylcaprolactone, β-propiolactone, γ-butyrolactone, δ-
The present invention relates to the first biodegradable agricultural multi-film of the present invention, which is a homopolymer of valerolactone or enantholactone, a copolymer of two or more monomers thereof, or a mixture of these homopolymers or copolymers. A third aspect of the present invention relates to the first biodegradable agricultural multi-film of the present invention, wherein the polylactone (b) is poly-ε-caprolactone. A fourth aspect of the present invention relates to the biodegradable agricultural multi-film according to any one of the first to third aspects of the present invention, wherein the radiation treatment is a gamma ray or electron beam irradiation treatment using an electron accelerator. A fifth aspect of the present invention is a resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c), which is irradiated with a radiation to obtain an aliphatic polyester resin. The present invention relates to a method for producing a biodegradable agricultural multi-film according to any one of the first to fourth aspects of the present invention, which comprises molding a composition. A sixth aspect of the present invention is a resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or a polylactone (b) and diatomaceous earth (c), which is irradiated with a radiation to obtain an aliphatic polyester resin. While extruding the composition into a tubular film from an annular die, blowing gas into the tubular film,
The present invention relates to the method for producing a biodegradable agricultural multi-film according to any one of the first to fourth aspects of the present invention, wherein the tubular film is expanded by the pressure of the gas and then folded by nip rolls. A seventh aspect of the present invention is to form a resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c), and subjecting the obtained film to radiation irradiation treatment. The present invention relates to a method for producing a biodegradable agricultural multi-film according to any one of the first to fourth aspects of the present invention. Eighth of the invention
A resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c) is extruded from an annular die into a tubular film,
The first to fourth aspects of the present invention are characterized in that a gas is blown into the tubular film, the tubular film is expanded by the pressure of the gas, then folded by nip rolls, and the obtained film is irradiated with radiation. The present invention relates to a method for producing any of the biodegradable agricultural multi-films.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The dehydration-condensation type aliphatic polyester resin used in the present invention is not particularly limited, but a biodegradable polyester resin such as synthetic polylactic acid, polyethylene succinate, polybutylene succinate (such resin as Can be exemplified by a polyester resin synthesized from a low-molecular-weight aliphatic dicarboxylic acid and a low-molecular-weight aliphatic diol typified by Bionole of Showa Polymer Co., Ltd.), a 3-hydroxyalkanoate unit (3-hydroxybutyrate). Polyesters containing acrylate, 3-hydroxyvalerate, 3-hydroxycaprolate, 3-hydroxyheptanoate) P (3H
A) Copolymer｝, 3-hydroxybutyrate (3HB)
And a copolymer comprising 3-hydroxyvalerate (3HV) units {for example, a P (3HB-co-3-HV) copolymer having a 3HV fraction of 0 to 25 mol%: manufactured by ICI,
Trade name “Biopole”｝, JP-A-9-235360, 9-235360
Examples include ternary copolymer aliphatic polyesters described in JP-A-233956 and lactic acid-hydroxycarboxylic acid copolymers described in JP-A-7-177826. Above all, melting point is 100
It is preferable that the resin has a thermoplastic property at a temperature of not less than ℃ and a relatively low biodegradability. Polyester resin obtained from succinic acid and 1,4-butanediol, polyester resin obtained from succinic acid and ethylene glycol, oxalic acid And polyester resins obtained from oxalic acid and 1,4-butanediol, polyester resins obtained from oxalic acid and ethylene glycol, and the like. Particularly preferred are succinic acid and 1,1,4-butanediol. 4Polyester resin obtained from butanediol. The preferred number average molecular weight of the aliphatic polyester resin is 20,000 or more, more preferably 4
It is in the range of 0,000 or more. There is no upper limit, but practically 50
About 000 can be used.

As the aliphatic polyester resin used in the present invention, those containing a urethane bond can be used. The aliphatic polyester resin containing a urethane bond is obtained by increasing the molecular weight of the aliphatic polyester resin, preferably with an aliphatic diisocyanate compound. Examples of the aliphatic diisocyanate compound include hexamethylene diisocyanate, lysine diisocyanate methyl ester {OCN— (CH ₂ ) ₄ —CH (—NCO) (— COOCH ₃ )}, and trimethylhexamethylene diisocyanate. Diisocyanates are preferred. The number average molecular weight of the aliphatic polyester resin containing a urethane bond is preferably 20,000 or more, more preferably 40,000 or more. Showa Polymer Co., Ltd. is an aliphatic polyester resin containing a urethane bond.
Bionole $ 1000, # 3000, $ 6000 series.

The polylactone used in the present invention is ε-
Caprolactone, 4-methylcaprolactone, 3,5,5-
Homopolymers of various methylated caprolactones such as trimethylcaprolactone and 3,3,5-trimethylcaprolactone, β-propiolactone, γ-butyrolactone, ∂-valerolactone, enantholactone, or copolymers of two or more of these monomers And a mixture of homopolymers and copolymers thereof. The polylactone used in the present invention may be copolymerized with a lactone monomer and a monomer other than the lactone monomer, for example, lactic acid, hydroxypropionic acid, aliphatic hydroxycarboxylic acids such as hydroxybutyric acid; exemplified by the aliphatic polyester described below. Aliphatic diols and aliphatic dicarboxylic acids, particularly those that do not soften at room temperature are preferred, and from this viewpoint, poly ε-caprolactone, which has a high molecular weight and a melting point of 60 ° C. or higher, is easy to obtain stable performance, is preferred. is there. The polycaprolactone used in the present invention is obtained by subjecting ε-caprolactone to ring-opening polymerization in a conventional manner using an active hydrogen-containing compound such as an alcohol as an initiator. The functional number of the initiator is not particularly limited, and bifunctional or trifunctional ones can be preferably used. The molecular weight of polycaprolactone is
Although it can be used from low molecular weight to high molecular weight, when using low molecular weight polycaprolactone, the amount of addition is limited because the heat resistance and mechanical strength of the resin decrease greatly,
Merits such as a decrease in the melt viscosity of the resin composition and an improvement in moldability are exhibited. However, it is more preferable to use polycaprolactone having a high molecular weight, since the compounding ratio can be increased, and all of heat resistance, mechanical properties, and biodegradability can be highly balanced. Specifically, the number average molecular weight is preferably 10,000 to 500,000, but 30,000 to 200,000 is particularly preferable in terms of efficient crosslinking. The polycaprolactone having the above molecular weight has a relative viscosity of 1.15 to 2.80 according to JIS K6726, and particularly preferably has a relative viscosity of 1.50 to 2.80. Note that 200, 0
Although those having a number average molecular weight higher than 00 can be used without any problem, it is difficult to obtain such a very high molecular weight polycaprolactone, which is not practical. Also,
The polycaprolactone to be used is, in addition to the homopolymer of ε-caprolactone, the above-mentioned polylactone, glycolide,
Comonomer structural units such as lactide, for example, 20 mol%
The copolymers contained below can also be used. Examples of polycaprolactone include PCLH7 and PLH manufactured by Daicel Chemical Industries, Ltd.
CLH4, PCLH1 and the like.

When the aliphatic polyester resin and the polylactone are used in combination, the mixing ratio is not particularly limited, and can be appropriately selected depending on the molecular weight of both, the required biodegradability, and the required physical properties.

When the aliphatic polyester resin and the polylactone are kneaded, it is preferable that they are compatible with each other from the viewpoint of the mechanical properties of the resin composition obtained by kneading. Addition of a compatibilizer such as a copolymer of a resin component to be kneaded and a polylactone component, for example, a resin having an intermediate polarity between the two can also be preferably used.

The dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) used in the present invention may be mixed with other biodegradable resins. As the other biodegradable resin, a synthetic and / or natural polymer is used. Examples of the synthetic polymer include polyamide, polyamide ester, biodegradable cellulose ester, polypeptide, polyvinyl alcohol, and a mixture thereof. Examples of the biodegradable cellulose ester include organic acid esters such as cellulose acetate, cellulose butyrate, and cellulose propionate; inorganic acid esters such as cellulose nitrate, cellulose sulfate, and cellulose phosphate; cellulose acetate butyrate, cellulose acetate phthalate, and nitric acid. Hybrid esters such as cellulose acetate can be exemplified. These cellulose esters can be used alone or in combination of two or more. Among these cellulose esters, organic acid esters, particularly cellulose acetate, are preferred. Examples of the polypeptide include polyamino acids such as polyglutamic acid and polyamide esters. Examples of polyamide esters include resins synthesized from ε-caprolactone and ε-caprolactam. As an example of the synthetic polymer, for example, an aliphatic polyester resin has a number average molecular weight of 20,000 or more and 200,000 or less, preferably 4
More than 000 can be used.

Natural polymers include flour, cellulose,
Paper, pulp, cotton, hemp, wool, silk, leather, carrageenan, chitin / chitosan, natural linear polyester resin, or a mixture thereof. Examples of the starch include raw starch, processed starch, and a mixture thereof. As raw starch, corn starch, potato starch, sweet potato starch,
Wheat starch, cassava starch, sago starch, tapioca starch, rice starch, legume starch, kudzu starch, bracken starch, lotus starch, sis starch, and the like. , Moist heat-treated starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzyme-decomposed dextrin, amylose, etc.), chemically-modified starch (acid-treated starch, hypochlorite-oxidized starch, dialdehyde starch, etc.), chemically-modified starch derivative ( Esterified starch, etherified starch, cationized starch, cross-linked starch, etc.). Among the above, as the esterified starch, acetate-starch, succinate-starch, nitrate-starch, phosphate-starch, urea-phosphate-starch, xanthate-starch, acetoacetate-starch Etc .; etherified starches such as allyl etherified starch, methyl etherified starch, carboxymethyl etherified starch, hydroxyethyl etherified starch and hydroxypropyl etherified starch; etc .; cationic starches include starch and 2-diethylaminoethyl chloride. , A reaction product of starch and 2,3-epoxypropyltrimethylammonium chloride, etc .;
Formaldehyde cross-linked starch, epichlorohydrin cross-linked starch, phosphate cross-linked starch, acrolein cross-linked starch, and the like.

In the present invention, diatomaceous earth is used. Diatoms are a general term for algae of the brown phylum diatom net, which are phytoplankton of unicellular algae widely distributed in freshwater, brine, and soil, having many types, and having siliceous shells in cell membranes. Diatomaceous earth is
It is a siliceous sediment composed of the remains of plankton, containing organic matter, clay, and volcanic ash. It is produced in both marine and lake strata, and its main diatomaceous earth is from Tertiary. The shape has a large surface area due to the myriad of fine pores on the surface of the diatom shell, and it has excellent respiration and adsorption properties. Since diatomaceous earth is abundantly buried in the earth and can be obtained stably and at low cost, its use is useful in solving the problem of biodegradable plastics, which is a high price. Addition of diatomaceous earth further improves biodegradability and increases melt strength (viscosity), preventing drawdown during melt molding and improving moldability such as vacuum molding, blow molding, and inflation molding. . By further irradiating the radiation, the melt strength is further increased, and the tear strength of the obtained film is improved. This seems to be due to the crosslinking reaction between the aliphatic polyester and the organic matter in the diatomaceous earth caused by the radiation. If the diatomaceous earth used in the present invention is too purified, the organic matter in the diatomaceous earth will be lost, and the bridge between the dehydration-condensed aliphatic polyester resin (a) and / or polylactone (b) and the diatomaceous earth during irradiation is irradiated. It is rather unpreferable because a cross-linking reaction hardly occurs. The amount of diatomaceous earth to be added is such that the weight ratio of diatomaceous earth / (total of aliphatic polyester resin and polycaprolactone) is 1 to 50/99 to 5 with respect to the total of aliphatic polyester resin and polycaprolactone.
0, preferably 3 to 30/97 to 70, more preferably 5 to 20/9
5 to 80. If the amount of diatomaceous earth is excessive, the resin blows powder, and depending on the type, pyrolysis may be accelerated and the pyrolysis temperature may decrease. If the amount is too small, the effect of improving the formability is not sufficient, and drawdown, necking, uneven thickness and eyes are remarkably generated during molding.

In the present invention, the dehydration-condensation type aliphatic polyester resin (a) used in the present invention and / or
Alternatively, a resin additive may be added to the polylactone (b) as needed. As resin additives, plasticizers, heat stabilizers, lubricants, antiblocking agents, nucleating agents, photolytic agents, biodegradation accelerators, antioxidants, ultraviolet stabilizers, antistatic agents, flame retardants,
Dropping agents, antibacterial agents, deodorants, fillers, coloring agents, or mixtures thereof, may be mentioned.

Examples of the plasticizer include aliphatic dibasic acid esters, phthalic acid esters, hydroxy polycarboxylic acid esters, polyester plasticizers, fatty acid esters, epoxy plasticizers, and mixtures thereof. Specifically, phthalic acid esters such as di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP), and diisodecyl phthalate (DIDP); di-2-ethylhexyl adipate (DOA); diisodecyl adipate Adipic acid esters such as (DIDA), azelaic acid esters such as azelaic acid-di-2-ethylhexyl (DOZ), hydroxy polycarboxylic acid esters such as acetyl tri-2-ethylhexyl and acetyl tributyl citrate, and polypropylene glycol adipin Examples include polyester-based plasticizers such as acid esters, which may be used alone or in a mixture of two or more. As the amount of addition of these plasticizers,
Although it depends on the application, it is generally a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) 100
3 to 30 parts by weight, preferably 5 to 15 parts by weight,
A range of parts by weight is more preferred. If it is less than 3 parts by weight,
If the elongation at break or the impact strength is reduced, and if it exceeds 30 parts by weight, the strength at break or the impact strength may be reduced.

As the heat stabilizer, there is an aliphatic carboxylate. As the aliphatic carboxylic acid, an aliphatic hydroxycarboxylic acid is particularly preferred. As the aliphatic hydroxycarboxylic acid, naturally occurring ones such as lactic acid and hydroxybutyric acid are preferable. Salts include sodium, calcium,
Aluminum, barium, magnesium, manganese,
Examples include salts of iron, zinc, lead, silver, copper, and the like. They are,
One or a mixture of two or more can be used. The addition amount of the dehydration-condensation type aliphatic polyester resin (a) and / or polylactone used in the present invention is
(b) It is in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight.
When the heat stabilizer is used within the above range, the impact strength (Izod impact value) is improved, and there is an effect that variations in elongation at break, strength at break, and impact strength are reduced.

As the lubricant that can be used in the present invention, those generally used as an internal lubricant and an external lubricant can be used. For example, fatty acid esters, hydrocarbon resins, paraffins, higher fatty acids, oxy fatty acids, fatty acid amides, alkylene bis fatty acid amides, aliphatic ketones,
Examples include fatty acid lower alcohol esters, fatty acid polyhydric alcohol esters, fatty acid polyglycol esters, fatty alcohols, polyhydric alcohols, polyglycols, polyglycerols, metal soaps, modified silicones, and mixtures thereof. Preferably, fatty acid esters, hydrocarbon resins and the like are used. When a lubricant is selected, it is necessary to select a lubricant having a melting point not higher than the melting point of the dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) used in the present invention. For example, in consideration of the melting point of the aliphatic polyester resin, a fatty acid amide of 160 ° C. or lower is selected as the fatty acid amide. The blending amount is such that 0.05 to 5 parts by weight of a lubricant is added to 100 parts by weight of the dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) which is a raw material of the multi-film of the present invention. If the amount is less than 0.05 part by weight, the effect is not sufficient, and if the amount is more than 5 parts by weight, it is not wound around a roll, and the physical properties are deteriorated. For films, from the viewpoint of preventing environmental pollution,
Preferred are ethylene bisstearic acid amide, stearic acid amide, oleic acid amide, and erucamide, which are highly safe and are registered with the FDA (US Food and Drug Administration).

Examples of the photodegradation accelerator include benzophenones such as benzoins, benzoin alkyl ethers, benzophenone, 4,4-bis (dimethylamino) benzophenone and derivatives thereof; acetophenone,
acetophenones such as α, α-diethoxyacetophenone and derivatives thereof; quinones; thioxanthones; photoexcitants such as phthalocyanine, anatase-type titanium oxide, ethylene-carbon monoxide copolymer, sensitization of aromatic ketones with metal salts And the like. These photolysis accelerators are
One or two or more can be used in combination.

Examples of the biodegradation accelerator include oxo acids (for example, oxo acids having about 2 to 6 carbon atoms such as glycolic acid, lactic acid, citric acid, tartaric acid, and malic acid), saturated dicarboxylic acids (for example, Organic acids such as acids, malonic acid, succinic acid, succinic anhydride, glutaric acid, etc. and lower saturated dicarboxylic acids having about 2 to 6 carbon atoms); these organic acids and carbon number
Lower alkyl esters with about 1 to 4 alcohols are included. Preferred biodegradation accelerators include citric acid, Shun Taroku,
Organic acids having about 2 to 6 carbon atoms, such as malic acid, and coconut shell activated carbon are included. One or more of these biodegradation accelerators can be used in combination.

According to the present invention, the dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) are combined with diatomaceous earth.
The resin composition comprising (c) has been subjected to a predetermined radiation irradiation treatment. In the present invention, "a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth
(c) is a resin composition which has been subjected to radiation irradiation treatment "means that the dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c) are blended. Irradiation before, during or after molding. Further, the shape may be a powder, a pellet, a molding state, or a product state. Therefore, in the present invention, the resin composition comprising the aliphatic polyester resin (a) and / or the polylactone (b) and the diatomaceous earth (c) of the dehydration-condensation type is subjected to a predetermined radiation irradiation treatment in advance, and, for example, Type aliphatic polyester resin (a) and / or polylactone
In addition to the resin composition obtained by mixing (b) or further adding a fatty acid amide or the like, a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c)
A resin composition obtained by mixing a fatty acid amide or the like with a resin composition comprising the same, and performing the same radiation treatment, a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b), a fatty acid amide, and the like. The resin composition obtained by mixing the diatomaceous earth (c) and performing the above-described irradiation treatment is also included.
Further, for example, as an embodiment in which the three components are mixed and irradiated with radiation, a composition (eg, a strand for pellet production) at the time of producing pellets for molding is used.
Irradiating the film, forming the film, and irradiating the molded product. From the viewpoint of moldability during film formation, it is more preferable before molding. In addition, a mode in which irradiation is performed at a low dose first and then at a high dose at a later stage is also included. As a result, the melt viscosity becomes higher than that of the unirradiated one, so that the irradiation can be performed again while maintaining the shape at a higher temperature, the crosslinking occurs with a high probability, and the heat resistance is improved.

The radiation sources used in the radiation irradiation treatment according to the present invention include α-rays, β-rays, γ-rays, X-rays, electron beams,
Ultraviolet rays and the like can be used, but γ-rays, electron beams, and X-rays from cobalt 60 are more preferable. Among them, γ-rays, electron beam irradiation treatment using an electron accelerator can be used to introduce a crosslinked structure of a polymer material. Most convenient.

The irradiation dose is determined using the strain hardening index of the resin composition as a measure for introducing the bridge structure of the polymer as one scale. That is, the strain hardening index of the resin composition is
0.15 to 4.0, preferably 0.35 to 3.0, and more preferably 1.1 to 2.0, by subjecting the powder or beret-shaped resin composition to radiation irradiation treatment. Good. Due to the irradiation treatment, the strain hardening index of the resin composition was 0.15.
If the ratio is less than 1, the film formability is poor, and the thickness of the film becomes uneven. Also, the strain hardening index
If the ratio exceeds 4.0, gel tends to be generated in a film as a molded product, and the flowability is poor, so that the moldability is rather lowered. For multi-film applications, the radiation dose is appropriately selected depending on the type of resin used and required characteristics, but is generally 5 to 100 kGy, preferably 10 to 50 kGy. If the amount is too small, the crosslinking effect is poor, and if the amount is too large, the rubbery state is undesirably advanced. The atmosphere during the radiation treatment is not particularly limited, but it is advantageous that the lower the oxygen concentration, the higher the bridging efficiency and the smaller the irradiation dose.

As a method for obtaining a blended composition obtained by adding the various additives to the biodegradable resin composition, various methods conventionally used can be applied, and are not particularly limited. The compounded composition is prepared by a single-screw or twin-screw extruder.
Melt kneading is performed at about 40 to 210 ° C. to obtain powder or pellets of the resin composition containing various additives.

The powder- or pellet-shaped additive-containing resin composition thus obtained is subjected to an inflation method,
-It can be formed into a film by molding using various conventional molding methods such as a die method. Further, the film can be processed into an agricultural multi-film or the like by laminating the film with a single layer or with paper or nonwoven fabric.

A preferred example in the case of forming a film, particularly a film by the inflation method, will be described below. First, the mixing ratio of polylactone and dehydration-condensation type aliphatic polyester resin is not particularly limited. The mixing ratio of the diatomaceous earth is as described above. The blending ratio of the fatty acid amide as a lubricant is preferably from 0.2 to 5 parts by weight based on 100 parts by weight of the total of the polylactone and the aliphatic polyester resin.
The range is more preferably from 0.3 to 1.5 parts by weight. If the fatty acid amide is less than 0.2 parts by weight, the blocking effect in the tube of the inflation film or the blocking prevention effect between the film and the nip roll or the guide roll is slightly lowered,
On the other hand, if it exceeds 5 parts by weight, the slipperiness of the film tends to be unnecessarily high, and in addition to the problem of collapse of roll winding, printability, adhesiveness, etc., begin to show a tendency to decrease. Further, if necessary, a liquid lubricant, fine powder silica, starch and the like can be added. The purpose of using the liquid lubricant is that a polylactone or an aliphatic polyester resin as a resin component constituting the resin composition is usually supplied in the form of pellets or beads to an inflation film-forming process, and a fine powder having an extremely small bulk specific gravity as described below. When trying to mix powdered silica etc. uniformly,
This is because it is preferable to keep the surfaces of the pellets and beads as wet as possible. The addition amount of the liquid lubricant having such a purpose of use is preferably 0.1 to 3 parts by weight, more preferably 0.2 to 0 parts by weight, based on 100 parts by weight of the total amount of polylactone and / or aliphatic polyester resin. It is added in a range of 0.7 parts by weight. If the added amount exceeds 3 parts by weight, a large amount of the liquid lubricant adheres to the inner surface of the tumbler for mixing, and sticky and stable mixing may be difficult. If the added amount is less than 0.1 part by weight, the effect as a wetting agent is sufficient. May not be able to demonstrate. This tendency is more preferable from 0.2 to
It is also found outside the range of 0.7 parts by weight. On the other hand, a liquid lubricant as a wetting agent preferably has a melting point of 70 ° C. or lower, and a liquid lubricant at room temperature is more preferably used. For example, besides liquid paraffin, paraffin wax, stearyl alcohol, stearic acid, etc., butyl stearate,
Examples thereof include stearic acid esters such as stearic acid monoglyceride, pentaerythritol tetrastearate, and stearyl stearate. The most preferred liquid paraffin among the above liquid lubricants is very safe because of its oral acute toxicity (rat) LD50 of 5 g / kg, and is recognized as a food additive in the Food Surgery Act. It is a very convenient material in terms of prevention of environmental pollution in the case where it is performed. As described above, a liquid lubricant was selected as the lubricant, but if a solid lubricant is used, the entire system including the resin composition needs to have a melting point of the solid lubricant or higher, and a low temperature of the melting point or lower. It is difficult to use. Liquid paraffin, which is liquid at room temperature, is a preferred lubricant in this regard. The purpose of using the finely divided silica is to prevent the above-mentioned blocking at the time of inflation film and inflation film formation. The finely divided silica used is, for example, silica produced by a wet process or silica produced by high-temperature hydrolysis of silicon tetrachloride in an oxyhydrogen flame. Is preferred. As the addition method, the method of heating and kneading the aliphatic polyester-based resin composition according to the present invention is most preferable, and a considerably high shearing force acts to loosen the secondary agglomerated particles, between the film and between the film and each roll. It has the effect of blocking and preventing stickiness. The addition amount of the finely divided silica is most preferably in the range of 0.1 to 3 parts by weight based on 100 parts by weight of the aliphatic polyester-based resin composition according to the present invention, in view of the above effects.

As a method for obtaining a compounded composition obtained by adding the various additives to the resin composition, various methods conventionally used can be applied, and are not particularly limited.
For example, to explain an example of a method for producing the above-mentioned blended composition, first, a polylactone and / or an aliphatic polyester resin and a liquid lubricant are put in a tumbler and stirred and mixed for 10 to 20 minutes, and then a fatty acid amide is added. Add diatomaceous earth, finely divided silica and starch to the mixture and stir and mix for another 20-30 minutes. After that, 140 single-screw or twin-screw extruder
Melt kneading is performed at about 210 ° C. to obtain powder or pellets of the resin composition containing various additives. As described above, the irradiation treatment may be appropriately performed in this step.

The melt fluidity of the aliphatic polyester resin composition subjected to the specific radiation treatment is not particularly limited as long as the resin composition can be subjected to a film forming step. , MI (measured under a load of 2160 g at 190 ° C.) is preferably 0.3 to 20 g / 10 min.
0.5-3g / 10min is suitable. Next, the film formation will be described. The raw resin composition is supplied to an extruder equipped with an annular die, melt-kneaded at a temperature of about 180 ° C., and extruded into a tube shape from an annular die slit. At this time, the extrusion diameter of the extruder is about 40 to 65 mm, and the length / diameter ratio (L / D) is
26-32, the diameter of the annular die is 50-150 mm, and the gap of the die slit is preferably in the range of 0.5-1.5 mm. The extruded tube-shaped unsolidified blown film expands to a predetermined diameter by setting the blow ratio (tube diameter / die diameter) to 2 or more by the pressure of the gas introduced from the gas blowing pipe inserted through the die. Then, it is folded by a nip roll and taken up at a constant speed, and is wound up as a tubular film or cut in the take-up direction as a wide film. The resin composition obtained through the radiation treatment step comprises a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth.
The film can be stably produced regardless of the temperature of the resin extruded from the annular die, probably because of the crosslinked structure of (c). According to the present invention, the diatomaceous earth-containing resin composition in the form of powder or pellets, compared with a conventional polylactone or a composition thereof without irradiation treatment, is improved in inflation by improving the melt viscosity which is considered to be based on its crosslinked structure. It can also be applied to various conventional molding methods other than the film forming method.

In the case of molding into a film, after irradiation, the dehydration-condensation type aliphatic polyester resin (a) and / or
Or M of the resin composition consisting of polylactone (b) and diatomaceous earth
The degree of crosslinking is preferably such that I is 0.3 or less (ie, low gel fraction).

The resin composition according to the present invention or the resin composition containing various additives can stably produce a film at an environmental temperature close to room temperature regardless of the temperature of the resin extruded from the annular die. However, when the outside air temperature is extremely high, such as in summer, a more completely blocking-free film can be obtained by introducing cold air of 20 ° C. or less through the gas blowing pipe.

Although the thickness of the agricultural multi-film according to the present invention is not particularly limited, it is appropriately selected depending on whether or not it is house cultivation or a plant to be cultivated. It can be usually used, and the thickness is preferably from 10 μm to 1 mm, more preferably from 15 to 100 μm. The film may have a multilayer structure depending on the purpose, or may be coated with an acrylic resin on one or both surfaces of the film. Thereby, weather resistance, stain resistance, abrasion resistance, heat retention, moisture retention, anti-fogging properties, fog resistance, dropping properties, and the like can be improved. Examples of the acrylic resin include an acrylic resin composed of methyl (meth) acrylate, alkyl (meth) acrylate having 2 to 4 carbon atoms, hydroxyethyl (meth) acrylate, and a mixture thereof. You.

The agricultural multi-film according to the present invention can be reduced to a desired strength after a predetermined period, so that it can be plowed if necessary, and then placed in a biodegradable environment. .

[0046]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the Examples, “%” and “parts” are based on weight unless otherwise specified. [Measurement and Evaluation Methods] The physical properties of the resin were measured and evaluated by the following methods. Measurement of molecular weight The molecular weight was determined by measuring the molecular weight by GPC manufactured by TOYOSODA (HCL-802A). Evaluation of thermal behavior For evaluation of thermal behavior, the melting point was determined at a rate of temperature increase of 10 [° C / min] using DSC-7 manufactured by PerkinElmer. The temperature was raised at a rate of 10 [° C / mi using TGA-50 manufactured by Shimadzu Corporation.
n], the thermal decomposition behavior was examined. Evaluation of mechanical behavior A tensile tester manufactured by TOYOBALDWIN (TENSILON / UTM-III-500) was used. For the measurement, a film sample was cut out to a width of 5 mm, irradiated for a predetermined time, and C.I. HSpeed (5mm / m
In), the Young's modulus, cutting strength and elongation were determined. Measurement of melt viscosity, shear stress, and shear modulus The melt viscosity and shear stress were measured by CAPIROGRAPH-2 manufactured by Toyo Seiki Seisaku-sho, Ltd. The set temperature for measurement is 15
The temperature was set to 0 ° C. Shear modulus was also measured at a sample temperature of 70 ° C. Measurement of Elongational Viscosity A sample having a diameter of 5 mm and a length of 300 m was set in a sample holder of Melten Rheometer-670 (manufactured by Toyo Seiki) and measured. Before the measurement, the sample was completely relaxed in a 70 ° C. silicone oil bath for 10 minutes before use. Uniaxial elongational viscosity is 70
Measured in ° C. To measure the actual strain rate, the sample diameter during elongation was monitored by a CCD camera. The set strain rate was 0.001 to 0.5 s ^-1 . Measurement of dynamic modulus of elasticity This measurement involves the use of a rheometric solids
olids Analyzer (RSAII) was used. Sample size is 5 × 30m
It was used with a thickness of 0.5mm in m ^2. Measurement temperature range is -150 ° C
Up to ~ 300 ° C, the strain amplitude was measured at a frequency of 10 Hz and the strain amplitude was 0.5 mm. The following reagents were used for the enzyme degradation of the enzyme degradation test sample. Reaction mixture: 0.2 M phosphatebuffer (pH 7.0): 4.0 ml Lipase AK enzyme (10 mg / ml): 1.0 ml 0.1% surfactant (MgCl ₂ ): 1.0 ml For each 1 cm ³ sample After placing in a test tube and reacting for a predetermined time while shaking in a bath at 40 ° C., washing with distilled water and methanol, measuring the weight after drying to a constant weight with a vacuum dryer, The rate of weight loss was determined from the following equation and used as a measure of biodegradability. Weight reduction rate (%) = [(W−Wd) / W] × 100 W: weight before decomposition (g) Wd: weight after decomposition (g) Surface observation by scanning electron microscope (SEM) For some of the samples before and after disassembly, the films were placed on a gold plate, and the surface of the gold-deposited sample was observed at a magnification of 150 times.

[0047]Sample preparation The sample was polycaprolactone manufactured by Daicel Chemical Industries, Ltd.
(Hereinafter abbreviated as PCL) Praxel-H7 and blend sample
Diatomaceous earth manufactured by Wako Pure Chemical Industries, Ltd.
And Sigma Corporation (hereinafter sigma diatomaceous earth)
Diatomaceous earth). Introduction PCL 2
Dry for 4 hours under reduced pressure and make Kodaira to mix with diatomaceous earth
Roll temperature is 160 ° C using a mixing roll manufactured by Toshosha
And kneaded for 20 minutes. The mixing ratio of diatomaceous earth is
The weight fraction was set to 0%, 6%, 10%, and 20%. Mixed
The sample was placed on a hot press and cold press manufactured by Ikeda Machinery Co., Ltd.
First, pre-heat at 160 ° C for 6 minutes with hot press, then 6 minutes
After pressurizing at 160 atm, circulate tap water for 8 minutes with a cold press.
Cooling by forming a ring
The material was used for the measurement. Irradiation method Irradiation is performed by packing the sample in a vacuum
Gamma rays from 0 at a dose rate of 10 [kGy / hr] for a predetermined time
Irradiation was performed. Immediately after irradiation, place the sample in the oven for 60 minutes.
Annealing was performed at 30 ° C. for 30 minutes.

[Reference Comparative Example 1] PCL and PCL / diatomaceous earth (wako)
The thermal behavior was evaluated by changing the blending ratio of the blend. In addition, the thermal behavior was evaluated by changing the mixing ratio of diatomaceous earth of PCL and PCL / diatom (sigma) blend. 1st run for each
The melting temperature peak was determined from the DSC curve of the (first measurement) and the DSC curve of the second run (second measurement). Table 1 shows the relationship between the melting temperature peaks of the first run and the second run of each sample and the mixing ratio of diatomaceous earth. 0% (PCL) in the table is a case where diatomaceous earth is 0%, that is, only PCL.

[0049]

[Table 1]

In Table 1, the peak temperature of the melting point hardly changed even if the mixing ratio of diatomaceous earth was changed. Also 2nd ru
In n, the melting point is slightly lowered due to the blending of diatomaceous earth. It is thought that the result of crystal imperfection appeared more in the second run than in the first run.

FIG. 1 shows a TGA curve for diatomaceous earth (wako). The vertical axis is weight, the horizontal axis is temperature (Temperatur)
e). FIG. 2 shows a TGA curve for diatomaceous earth (sigma). FIG. 3 shows a TGA curve in which the blending ratio of diatomaceous earth of PCL and PCL / diatomaceous earth (wako) blend is changed. Fig. 4 shows the TGA of PCL and PCL / diatomaceous earth (sigma) blend with different diatomite content
The curve is shown.

In FIG. 1, as the temperature increases from room temperature or higher, the weight decreases to around 96%. this house
A large decrease was observed around 400 ° C. This is thought to be due to the weight loss due to the pyrolysis and gasification of the organic matter in the diatomaceous earth. On the other hand, in FIG. 2, no weight reduction was observed. In FIG. 3, there was a tendency that the temperature at which thermal decomposition began to occur decreased as the blending ratio of diatomaceous earth increased. It was found that diatomaceous earth (wako) is also a diatomaceous earth having a decomposition promoting property, as well as a function of accelerating thermal decomposition by blending inorganic substances such as zeolite and metal salts. At the measurement end temperature of 480 ° C., the residual amount was found to be proportional to the blending ratio of diatomaceous earth.
It was found that PCL was completely decomposed at 480 ° C. In FIG. 4, no change was observed in the decomposition curve even when the mixing ratio was changed. From this result, it was found that diatomaceous earth (sigma) did not have a decomposition promoting property and did not affect a decrease in heat resistance. From the above, the following has become clear regarding the blending effect of the PCL / diatomaceous earth blend. 1． Diatomaceous earth (wako) and diatomaceous earth (sigm
The blending of a) hardly changes the melting point.
2． PCL / diatomaceous earth (wako) blends are more thermally decomposed and the decomposition temperature is lower than the TGA as the blending ratio increases. 3． PCL / diatomaceous earth (sigma) blends have less effect on decomposition temperature than TGA.

[Reference Example 1] The blending ratio of diatomaceous earth in the PCL / diatomaceous earth blend was changed, and γ was determined for each sample.
The effects on various physical properties were investigated by changing the radiation dose. (Evaluation of molecular weight behavior) The molecular weight behavior was evaluated.
Shows the relationship between the molecular weight (Mn) of the irradiated PCL and the dose (Dose).

From this result, the molecular weight decreases as the irradiation amount increases. This is irradiated by PCL
It is considered that the main chain was cut and the molecular weight was reduced. (Evaluation of thermal behavior) Diatomaceous earth (wako) 6% in PCL and PCL, 1
Diatomaceous earth (sigm
A sample blended with 6%, 10% and 20% of a) was irradiated with γ-rays to evaluate the thermal behavior. The melting temperature peak was determined from the DSC curve of the first run and the DSC curve of the second run. The relationship between the melting temperature and melting enthalpy of the 1st run and 2nd run of each sample, the mixing ratio of diatomaceous earth, and the irradiation dose was determined using diatomaceous earth (wak
o) and diatomaceous earth (sigma) for Tables 2 and 3 respectively
It was shown to.

[0055]

[Table 2]

[0056]

[Table 3]

As is clear from Tables 2 and 3, the melting temperature of PCL hardly changed in the first run. In the 2nd run, the peak temperature tended to decrease. This is considered to be the result of failure at the interface between the crystalline region and the amorphous region when the sample was melted in the first run, and more incomplete crystal in the second run. 1st run for PCL / diatomaceous earth (wako) blend
Even if the mixing ratio of diatomaceous earth was changed in the second and the second run, the melting temperature was not affected, and the effect of irradiation was hardly observed. P for PCL / diatomaceous earth (sigma) blend
As with the CL / diatomaceous earth (wako) blend, changing the diatomaceous earth loading did not affect the melting temperature and showed little effect from irradiation.

The irradiation dose of the PCL / diatomaceous earth (wako) blend was 0 kGy, 30 kGy, 50 kGy, 100 kGy, and 160 kG, respectively.
FIGS. 6 to 10 show TGA curves for each mixing ratio of diatomaceous earth at y.
It was shown to.

In the unirradiated sample of FIG. 6, the TGA curve shifts to the lower temperature side as the blending ratio of diatomaceous earth increases, but it can be seen that the TGA curve shifts to the higher temperature side as the irradiation amount increases. However, the PCL / diatomaceous earth (wako) blend
The TGA curve was hardly affected by the dose.

The irradiation dose of the PCL / diatomaceous earth (sigma) blend was 0 kGy, 30 kGy, 50 kGy, 100 kGy, and 160 kGy, respectively.
FIGS. 11 to 15 show TGA curves for each blending ratio of diatomaceous earth in kGy.

From these results, it was found that the TGA curve did not change much at any irradiation dose, and that the irradiation of the PCL / diatomaceous earth (sigma) blend had almost no effect.

(Evaluation of Mechanical Behavior) The stress (Str
FIG. 16 shows the relationship between ess) and elongation (Strain). As shown in this figure, necking occurred at an elongation of about 80%, and PCL irradiated with 0 kGy was extended to about 900% and cut. The elongation decreased and the Young's modulus increased with an increase in the irradiation amount.

FIG. 17 shows the relationship between the Young's modulus and the dose (Dose) for each of the blending ratios of PCL and the PCL / diatomaceous earth (wako) blend. The Young's modulus increases as the blending ratio of diatomaceous earth increases, and the Young's modulus of a sample with a large irradiation amount further increases. This is thought to be due to the fact that the intermolecular slip was restricted by the effect of the crosslinking between PCL and diatomaceous earth in addition to the crosslinking between PCLs.

FIG. 18 shows the relationship between the Young's modulus and the irradiation dose for each of the blending ratios of PCL and PCL / diatomaceous earth (sigma) blend. In this figure, the Young's modulus increases as the blending ratio of diatomaceous earth increases, as in FIG. 17, but the Young's modulus is not as large as that of FIG. 17 as a whole.

FIG. 19 shows the cutting strength (Tensile Str) of a PCL / PCL / diatomaceous earth (wako, sigma) blend having a blending ratio of 20%.
and the dose (Dose). It can be seen that the cutting strength of PCL decreases as the irradiation dose increases. This seems to be due to radiolysis causing a decrease in cutting strength. In addition, the cutting strength was not affected by the irradiation dose in the PCL / diatomaceous earth (sigma) blend.
In the PCL / diatomaceous earth (wako) blend, the one with a large irradiation amount has a slightly increased cutting strength. This may be due to the cross-linking of diatomaceous earth and PCL.

FIG. 20 shows the elongation at break (Elongatio) of the PCL / PCL / diatomaceous earth (wako, sigma) blend having a blending ratio of 20%.
n at break) and the dose. PCL is 50k
Although the elongation at break decreases from around Gy, the breaking of molecular chains on the crystal surface starts around here, and the elongation at break also decreases from around 50 kGy for the PCL / diatomaceous earth (sigma) blend. In particular, the PCL / diatomaceous earth (wako) blend sharply reduced the elongation at break.

The following is clear from the above results. 1． Upon irradiation, PCL undergoes main chain scission and its molecular weight decreases, and the molecular weight decreases as the irradiation amount increases. 2． The melting temperature of the sample did not change regardless of the mixing ratio of diatomaceous earth, and the effect of irradiation was hardly observed. 3． The thermal decomposition temperature of PCL / diatomaceous earth (wako) blend decreases as the blending ratio increases, but heat resistance increases by irradiation. In addition, the PCL / diatomaceous earth (sigma) blend does not change the thermal decomposition temperature regardless of the diatomaceous earth blending rate or irradiation. Four. Irradiation of PCL increased Young's modulus, and decreased cutting strength and elongation at break. In addition, the Young's modulus further increased and the cutting strength and the elongation at break decreased as the blending ratio of diatomaceous earth increased. In particular, PCL / diatomaceous earth (wako) showed a remarkable increase in Young's modulus and a decrease in cutting strength and breaking elongation by irradiation.

[Reference Example 2] PCL and PCL / diatomaceous earth (wak
o) and PCL / diatomaceous earth (sigma) blend to investigate the effect of gamma irradiation on the improvement of workability. And the melt viscosity behavior by the mixing ratio of diatomaceous earth were studied. Also, the dynamic modulus of elasticity,
Melt viscosity was measured to evaluate the effect of improving moldability.

(Evaluation of Melt Viscosity Behavior 1) FIG. 21 shows the melt viscosity (Viscosity) for each shear rate of PCL.
FIG. 3 is a graph plotting the relationship between shearing stress and shearing stress for each dose.

From these results, it was found that the melt viscosity of PCL tended to increase as the irradiation amount increased in the low shear rate region. This is presumably because the irradiation of the PCL caused crosslinking to increase the melt viscosity. When PCL is irradiated at room temperature, it is reported that decomposition reaction has priority over crosslinking reaction at irradiation doses up to 50 kGy, so the increase in melt viscosity at 30 kGy and 60 kGy is not due to crosslinking. It is considered that the entanglement was caused by the branching of the polymer chains, resulting in an increase in the melt viscosity.

FIG. 22 shows the relationship between the melt viscosity and the shear stress for each shear rate at an irradiation dose of 0 kGy by PCL / diatomaceous earth (wako).
It is plotted regarding the diatomaceous earth compounding ratio of the blend. As a result, there was no difference between the melt viscosity and the shear stress before irradiation.

FIG. 23 shows the relationship between the melt viscosity and the shear stress for each shear rate at an irradiation dose of 30 kGy by PCL / diatomaceous earth (wak).
It is plotted with respect to the mixing ratio of diatomaceous earth in o). As a result, the melt viscosity and the shear stress tended to be slightly higher than those of the PCL, and the melt viscosity and the shear stress increased as the blending ratio increased.

FIG. 24 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 50 kGy with respect to the mixing ratio of wako diatomaceous earth. As a result, the mixing ratio was 10
% And 20% samples showed an increasing tendency in melt viscosity and shear stress in the low shear rate region.

FIG. 25 shows the relationship between the melt viscosity and the shear stress for each shear rate at an irradiation dose of 100 kGy by PCL / diatomaceous earth (wak).
It is plotted with respect to the mixing ratio of diatomaceous earth in o). As a result, in all the samples mixed with diatomaceous earth, the melt viscosity and the shear stress tended to increase in the low shear rate region, and the viscosity and the shear stress tended to further increase as the mixing ratio of the diatomaceous earth increased.

FIG. 26 shows the relationship between the melt viscosity and the shear stress for each shear rate at an irradiation dose of 160 kGy by PCL / diatomaceous earth (wak).
It is plotted with respect to the mixing ratio of diatomaceous earth in o). This result also shows that the melt viscosity and the shear stress further increased as shown in FIG. 25 as the shear rate decreased, and that the melt viscosity and the shear stress increased as the blending ratio increased.

From the results of FIG. 22 to FIG. 26, there is almost no difference between the unirradiated blend sample and PCL,
After Gy, the melt viscosity and shear stress increased as the irradiation dose increased compared to PCL alone, and it was found that the melt viscosity and shear stress tended to increase further with the increase in the diatomaceous earth compounding ratio. This is because the irradiation of the organic part of PCL and diatomaceous earth caused cross-linking, resulting in an increase in melt viscosity and shear stress. It is believed that the stress was increased.

FIGS. 27 to 31 show that each dose is 0 kGy, 30 kGy,
The relationship between melt viscosity and shear stress for each shear rate at kGy, 50 kGy, 100 kGy, and 160 kGy was determined using PCL / diatomaceous earth (sigm
It is a plot of the diatomaceous earth compounding ratio of a). Irradiation increases the melt viscosity and shear stress especially at low shear rates compared to non-irradiation. The irradiation dose is 0k
Addition of diatomaceous earth at Gy, 30 kGy, 50 kGy, and 100 kGy had almost no effect on the increase in melt viscosity and shear stress. It was enough. This is based on the TGA measurement results of PCL / diatomaceous earth (sigma) shown in FIG.
igma) does not undergo cross-linking, resulting in diatomaceous earth (sigm
The blend of a) appears to have little effect on increasing melt viscosity and shear stress.

(Evaluation of Melt Viscosity Behavior 2) FIG. 32 shows PCL and PC
It is the result of the melt viscosity measurement (vertical axis) by another measurement about the sample of the compounding ratio of 20% of L / diatomaceous earth (wako and sigma) blend. The horizontal axis is the angular velocity. From this result, in the low angular velocity region, the melt viscosity of PCL increases as the irradiation dose increases, and the PCL / diatomaceous earth (sigma) blend exhibits the same behavior as PCL alone. PCL / diatomaceous earth (wako) blends have significantly increased melt viscosity from low doses,
The same tendency as the results of FIGS. 22 to 26 was shown. In addition, the unirradiated sample did not affect the increase in melt viscosity regardless of which diatomaceous earth was blended.

(Evaluation of Shear Modulus) FIG.
CL / diatomaceous earth (wako) 20% blend, PCL / diatomaceous earth (sigm
a) The results of measuring the shear modulus (vertical axis) with respect to the angular velocity (horizontal axis) per unit time for each irradiation amount at a measurement temperature of 150 ° C. using a 20% blend as a sample are shown. From this result, PCL
By itself, the shear modulus increases as the dose increases in the low angular velocity region. Also, as the angular velocity increases, the shear modulus increases. PCL / diatomaceous earth (sigm
a) The shear modulus of the 20% blend showed the same tendency as PCL alone. However, irradiation of the PCL / diatomaceous earth (wako) blend increased the shear modulus more than PCL alone. This is probably because the shear modulus was further increased due to the cross-linking between PCL and the organic portion of diatomaceous earth in addition to the formation of cross-links between PCLs.

(Evaluation of Elongational Viscosity) FIGS. 34 to 36 show the results of measurement of the elongational viscosities (vertical axis) of samples irradiated with 0, 30, and 50 kGy when PCL was blended with 20% diatomaceous earth, respectively. The horizontal axis is the logarithmic value of the reciprocal of the strain rate. In FIG.
Unirradiated PCL alone had a strain rate of 0.09 s ^-1 and exhibited η _E from 0.01 to 0.15 MPa, and from 0.02 to 0.006 s ^-l.
It increases only to 0.2-0.3MPa. Also, 2
The viscosity of the sample of 0% diatomaceous earth blend increased only about 0.5 MPa at the maximum, and showed almost the same behavior as PCL. In contrast, PCL irradiated with 30 and 50 kGy has a maximum of 1 MPa
Eta _E is increased to the effect that intermolecular crosslinking is introduced it is observed. In addition, 20% diatomaceous earth (wako) blend PCL is 10-50M
The Pa also shows an increase in η _E and the sample shows an extreme increase in viscosity and slippage just before cutting. Meanwhile, 20% diatomaceous earth (si
gma) shows a very similar curve to the unblended PCL
This indicates that there is almost no crosslinking between L and diatomaceous earth due to irradiation.

(Evaluation of Dynamic Elastic Modulus (Temperature Dispersion)) FIG.
Is the measurement result of the dynamic elastic modulus for each irradiation dose of PCL. The breaking temperature starts to shift to the high temperature side at 50 kGy at which the crosslinking starts, and at 160 kGy, it shifts to the higher temperature side and breaks at around 200 ° C. FIG. 38 shows the results of measurement of the dynamic modulus of elasticity of a 20% diatomaceous earth sample of a PCL / diatomaceous earth (sigma) blend. From this result, at 50 kGy, the rupture temperature slightly shifted to a higher temperature side, but almost equal to that of PCL. It shows a similar tendency. FIG. 39 shows the results of measurement of the dynamic elastic modulus of a 20% diatomaceous earth sample of a PCL / diatomaceous earth (wako) blend. It can be seen that the breaking temperature sharply shifts to a higher temperature side from 30 kGy. This is thought to be the effect of diatomaceous earth (wako) and PCL crosslinking.

From the above, PCL irradiated with γ-ray and PCL
The melting characteristics of the PCL / diatomaceous earth (wako) and PCL / diatomaceous earth (sigma) blends revealed the following. 1． When PCL / diatomaceous earth (wako, sigma) blend is not irradiated, melt viscosity and shear stress do not increase compared to PCL even when diatomaceous earth (wako, sigma) is blended. 2． In PCL, the melt viscosity and shear stress increase as the irradiation dose increases. 3． In a PCL / diatomaceous earth (sigma) blend, the melt viscosity and shear stress increase above the PCL at low irradiation doses, and increase as the blending ratio increases. It behaves, and there is almost no irradiation effect of the diatomaceous earth blend. Four. In a PCL / diatomaceous earth (wako) blend, the melt viscosity and shear stress increase above the same dose of PCL as the dose increases, and further increase with increasing loading. Five. The shear modulus increases with increasing irradiation dose, and P
When irradiated CL / diatomaceous earth (wako) blend, PCL, PCL /
Shear modulus increases significantly more than diatomaceous earth (sigma). 6． At elongational viscosities, the irradiated samples show a viscosity increase and slip immediately before cutting, and in particular, the PCL / diatomaceous earth (wako) blends show an extreme viscosity increase and slip immediately before cutting when irradiated. 7． In the dynamic viscoelasticity, the fracture temperature of PCL starts to shift from 50 kGy to the high temperature side, and shifts to around 200 ° C. at 160 kGy. The PCL / diatomaceous earth (sigma) blend showed the same tendency as PCL alone. PCL / diatomaceous earth (wako) blend
The breaking temperature reaches around 200 ° C from 30 kGy.

Example 1 PCL Having Microbial Degradability
And PCL / diatomaceous earth (wako) and PCL / diatomaceous earth (sigma) blend to clarify the controllability of biodegradability
The radiation behavior by gamma irradiation was investigated. In addition, the time course of the sample due to enzymatic degradation was examined by SEM for the degradation process. (Evaluation of Enzyme Degradation Test) FIG. 40 shows the weight loss (We
ight loss). The horizontal axis is the enzyme decomposition reaction time (Reaction Time). From this result, the irradiation dose is 30kG
It was found that the decomposition was relatively faster in the y and 50 kGy samples than in the non-irradiated samples, and the decomposition was slower in the 100 kGy and 160 kGy samples than in the non-irradiated samples, and the weight loss was only about 10% at 160 kGy. Since the enzymatic decomposition is decomposed from the amorphous portion in the sample, it is considered that the decomposition reaction was prioritized in the samples of 30 kGy and 50 kGy, and as a result, the amorphous portion increased, so that the decomposition became easier. In addition, it is considered that the decomposability of a sample of 100 kGy, 160 kGy or the like was significantly reduced by the crosslinking reaction.
FIG. 41 shows the measurement results of weight loss due to enzymatic decomposition at 40 ° C. with respect to the blending ratio of the PCL / diatomaceous earth (wako) blend without irradiation. From this result, it can be seen that the degradability is promoted as the blending ratio of diatomaceous earth increases. This is probably because diatomaceous earth fell off during the decomposition and the surface area increased, thereby promoting the decomposition. In addition, the measurement results of the weight loss due to enzymatic decomposition at 40 ° C. regarding the blending ratio of the PCL / diatomaceous earth (sigma) blend at the end irradiation in FIG. 42 also show that the decomposition is promoted as the blending ratio of the diatomaceous earth increases. FIG. 43 shows PCL and PCL /
It is the measurement result with respect to the compounding rate of the weight reduction by the enzyme decomposition at 40 degreeC of the film of a diatomaceous earth (wako) blend. Films were prepared from PCL and PCL / diatomaceous earth irradiated at 160 kGy. From this result, as in the case of FIG. 41, the decomposition was promoted as the blending ratio of diatomaceous earth was increased, but the weight loss was reduced as a whole. It was also found that the degradability was significantly reduced due to the crosslinking reaction in the amorphous portion. PCL / diatomaceous earth (sigma) at an irradiation dose of 160 kGy in FIG.
The measurement results of the weight loss due to the enzymatic decomposition at 40 ° C. with respect to the blending ratio of the film of the blend also show that the overall degradability is significantly reduced. Films were prepared from PCL and PCL / diatomaceous earth irradiated at 160 kGy. FIG. 45 shows PCL /
Diatomaceous earth (wako) blended film diatomite blending ratio
Figure 4 shows the measurement results of weight loss due to enzymatic degradation at 40 ° C for each irradiation dose at 20%. Films were prepared from PCL / diatomaceous earth blend samples irradiated at different doses. From these results, the irradiation doses up to 0 kGy, 30 kGy, and 50 kGy were decomposed in substantially the same manner. Degradation of 100 kGy and 160 kGy samples was significantly reduced due to the effect of crosslinking. FIG. 46 shows the measurement results of the weight loss with respect to each irradiation amount when the blending ratio of diatomaceous earth of the PCL / diatomaceous earth (sigma) blend is 20%. The results also show that the degradation of the irradiated samples of 100 kGy and 160 kGy is lower than that of the non-irradiated samples.

Example 2 (Evaluation of Surface Observation by SEM) FIG.
It is an image by SEM (scanning electron microscope) before and after 12 hours and 24 hours after the decomposition of the sample (film) irradiated with 0 kGy. From this image, it can be seen that the size of the eroded hole is smaller in the 160 kGy sample than in the unirradiated sample. This is considered to be due to the difficulty of decomposition due to the crosslinking of PCL. FIG. 48 is an SEM image of a PCL / diatomaceous earth (wako) blend film at a diatomaceous earth compounding ratio of 5%. FIG.
It can be seen that the size of the eroded hole is larger than that of FIG. This is thought to be because the PCL around the diatomaceous earth was decomposed and the diatomaceous earth fell off, resulting in an increase in the surface area. Also, 16
The pore size of the sample of 0 kGy is also small due to the effect of crosslinking. FIG. 49 is also a SEM image of the PCL / diatomaceous earth (wako) blend film at a blending ratio of 20%. It can be seen that the erosion is further increased as compared with FIG. FIG. 50 is the same
5% PCL / diatomaceous earth (sigma) blended film
It is the image by SEM in. FIG. 51 shows a SEM at a blending ratio of 20% of a PCL / diatomaceous earth (sigma) blended film.
Image. 50 and 51 also show PCL / diatomaceous earth (wak
o) It can be seen that it undergoes the same decomposition process as the blend. Again, the size of the erosion hole is smaller than that of the unirradiated sample due to the effect of irradiation, and it can be seen that the higher the mixing ratio, the larger the erosion hole.

PCL irradiated with γ-rays, and PCL / diatomaceous earth (wak
o) By observing the decomposition behavior of PCL / diatomaceous earth (sigma) blend and the time course of the decomposition process by SEM, the following was found. l. PCL accelerates decomposition at irradiation doses of 30 kGy and 50 kGy.
At the irradiation doses of 0 kGy and 160 kGy, the decomposition is significantly reduced. 2． Similarly, the degradation of PCL / diatomaceous earth (wako, sigma) blends is significantly reduced at irradiation doses of 100 kGy and 160 kGy. 3． Degradation becomes faster as the blending ratio of diatomaceous earth increases in the blend of PCL / diatomaceous earth (wako, sigma). Four. From the SEM, the decomposition process is similar for all samples, but the irradiated sample is less likely to decompose due to the effects of crosslinking.

Next, an agricultural multi-film was manufactured and evaluated. The raw materials used were as follows, and the resin raw material used was dried (60 ° C. × 10 hours or more) in advance. PCL H7: Polycaprolactone (manufactured by Daicel Chemical Industries, Ltd.) Number average molecular weight: about 70,000 # 1903: Bionole # 190
3 (manufactured by Showa Polymer Co., Ltd.) polybutylene succinate,
Number average molecular weight 70,000

[Compounding and Production of Pellets] The above raw materials were blended at a ratio (parts by weight) shown in Table 4 using a tumbler, and γ-rays from cobalt 60 were irradiated at a dose rate of 10%.
Irradiation was performed for a predetermined time at [kGy / hr]. 60 after irradiation
Annealing was performed at 30 ° C. for 30 minutes. Various additives were blended at the ratios shown in Table 4 and compounded with a twin-screw extruder under the following extrusion conditions to produce pellets. <Extrusion conditions> C1 (under hopper): 100 ° C, C2: 180 ° C, C
3: 200 ° C, C4: 200 ° C, C5: 200 ° C, C
6: 210 ° C, C7: 210 ° C, AD (before die): 2
10 ° C., D (die): 200 ° C. The numbers 1 to 7 of C increase from the bottom of the hopper of C1 toward the die. The same applies to the numbering of the film forming step. The resin supplied from the hopper is C1
After being extruded from the (under the hopper) to D (die), it is cut by a pelletizer.

[Formation of Film] A film was formed using the above pellets. The method of forming the film is not particularly limited.
Die extrusion molding can be used, but this time it was formed into a film using inflation molding. The molding conditions are as follows. <Inflation molding conditions> C1 (under hopper): 100 ° C, C2: 180 ° C, C
3: 200 ° C, C4: 200 ° C, C5: 210 ° C, C
6: 210 ° C, AD (before die): 210 ° C, D (die) 1: 210 ° C, D (die) 2: 210 ° C. Pellets supplied from the hopper go from C1 (below the hopper) to D (die). It is extruded, and is extruded upward at D (die), expanded into a cylindrical shape by air pressure, and becomes a film. Film take-off speed: 17.0 to 20.0 m / min Lip width: 1.0 mm Film width: 1350 mm Film thickness: 20 μm

Examples 3 to 5 and Comparative Examples 1 to 5 The films thus obtained were used as agricultural multi-films.
Various evaluations shown below were performed using the various pellets and films described above, and the results are shown in Table 4.

Evaluation of Hand-Tearability The cut feeling of a polyethylene film (inflation molding), which is widely used as a general-purpose film at present, was evaluated by hand. As a criterion at this time, the overall tearability was sensually evaluated in addition to mere strength, such as resistance transmitted to the hand when the hand was torn, how to tear (with or without linearity), and waving of the tear surface. The evaluation criteria for the sensory evaluation are as follows. ：: The tear surface is wavy, tears diagonally, and has high tear resistance. ：: The tear surface is linear and has little waving, but has a large tear resistance. X: The tear surface is linear and the tear resistance is small. XX: Tear resistance is smaller than that of X, and tear is easily propagated.

Tear strength sample: Each of the films obtained above was cut to a width of 50 mm and a length (MD direction) of 100 mm, and a cut of 30 mm in the length direction from the center at one end of the width was used. . The sample was conditioned for 24 hours in a thermo-hygrostat at 23 ° C. × 50% RH and used for measurement. <Tear strength measurement conditions> Sample length (distance between chucks): 50 mm Equipment used: manufactured by OLIENTEC, trade name RTA-50
0 Load cell: 5 kgf, 20% Cross head speed: 500 mm / min Number of tests: n = 3, and the results are shown as average values. The evaluation criteria for the sensory evaluation are as follows. ：: Strong tear strength, tears diagonally, and tear surface is wavy. ：: Strong tear strength, linear tear surface, wavy tear surface. X: The tear strength is weak and the tear surface is linear. XX: tear strength is very weak, the tear surface is linear, and the tear surface has almost no waviness.

Evaluation of Formability The pellets of each compound obtained above were formed into a 3 mmφ strand using a single screw extruder, and cut into appropriate lengths, and the uniaxial elongational viscosity was measured as a sample. At this time, whether each sample has strain hardening,
The moldability was evaluated organoleptically based on the degree of strain hardening. A: Strain hardening is very large and inflation molding is possible. ：: Strain hardening, the degree of which is not large, but inflation molding is possible. ×: No strain hardening property, and inflation molding is impossible.

Simple Degradation Test Using Biodegradable Activated Sludge (JIS K-695)
The biodegradability was evaluated according to 0). Biodegradability (weight%) after 28 days of test using Himeji standard activated sludge
Was measured. In addition, the biodegradability value obtained above is 6
Those with 0% or less were marked with x, those with 60% or more were marked with ○, and those with 80% or more were marked with ◎.

[0094]

[Table 4]

First, Comparative Examples 1 to 5 were diatomaceous earth and / or γ
There is no line irradiation. Comparative Example 1 has biodegradability but does not have tear resistance, and Comparative Example 2 also shows high workability but does not have tear resistance. Comparative Examples 3, 4 and 5 also have no tear resistance. From a comparison between Example 3 and Comparative Example 3,
It can be seen that the tear strength is clearly improved by irradiation with diatomaceous earth. In addition, in the sensory evaluation when actually tearing by hand, it was confirmed that the fracture surface was wavy and clearly changed. Also on diatomaceous earth
In the case of Examples 3 and 5 using a wako product, the tear strength is remarkably improved as compared with Comparative Examples 1, 2 or 4, 5 in which nothing is added. In addition, it can be confirmed that in Example 3, the resistance at the time of tearing of the resin itself and the waving of the fractured surface are clearly improved as compared with Comparative Examples 1 and 2 in the feeling of hand tearing. The same can be said for Example 5 with respect to Comparative Examples 4 and 5. From the above, it was confirmed that the present invention can provide a degradable agricultural multi-film having practical performance while maintaining moldability and biodegradability.

[0096]

As described above, the aliphatic polyester resin composition provided by the present invention is a composition comprising a dehydration-condensed aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c). By subjecting the material to irradiation treatment, the melt tension during high-temperature molding is high, the strain hardening property is improved, it can be applied to various moldings such as blow molding without trouble, and it has excellent biodegradability. Therefore, the degradable agricultural multi-film according to the present invention obtained by molding the resin composition is easier to mold and produce more easily than the agricultural multi-film using an existing biodegradable resin. Degradability is not inferior. In addition to this, the physical performance (particularly the tear strength) is dramatically improved, so that the original performance of the multi-film can be sufficiently exhibited. In addition, it was found that the strength can be easily reduced to a value that allows easy plowing when the desired predetermined period elapses, and that biodegradation occurs at a necessary and sufficient speed after being buried in the soil.

[Brief description of the drawings]

FIG. 1 shows a TGA curve for diatomaceous earth (wako).

FIG. 2 shows a TGA curve for diatomaceous earth (sigma).

FIG. 3 shows TGA curves of PCL and PCL / diatomaceous earth (wako) blend at different blending ratios of diatomaceous earth.

FIG. 4 shows TGA curves of PCL and PCL / diatomaceous earth (sigma) blend at different diatomaceous earth loadings.

FIG. 5 shows the relationship between the molecular weight and irradiation amount of PCL irradiated by GPC.

FIG. 6 shows TGA curves for PCL / diatomaceous earth (wako) blends for each blending ratio of diatomaceous earth.

FIG. 7 shows TGA curves for PCL / diatomaceous earth (wako) blends at different doses of diatomaceous earth at an irradiation dose of 30 kGy.

FIG. 8 shows TGA curves for PCL / diatomaceous earth (wako) blends at various doses of diatomaceous earth at an irradiation dose of 50 kGy.

FIG. 9 shows TGA curves for each blending ratio of diatomaceous earth at an irradiation dose of 100 kGy for a PCL / diatomaceous earth (wako) blend.

FIG. 10 shows TGA curves for each blending ratio of diatomaceous earth at a dose of 160 kGy for a PCL / diatomaceous earth (wako) blend.

FIG. 11. PCL / diatomaceous earth (sigma) blend
2 shows TGA curves for each mixing ratio of diatomaceous earth.

FIG. 12. PCL / diatomaceous earth (sigma) blend
3 shows TGA curves for each mixing ratio of diatomaceous earth at an irradiation dose of 30 kGy.

FIG. 13: PCL / diatomaceous earth (sigma) blend
FIG. 4 shows TGA curves for each mixing ratio of diatomaceous earth at an irradiation dose of 50 kGy.

FIG. 14: PCL / diatomaceous earth (sigma) blend
3 shows TGA curves for each mixing ratio of diatomaceous earth at an irradiation dose of 100 kGy.

FIG. 15: PCL / diatomaceous earth (sigma) blend
3 shows TGA curves for each blending ratio of diatomaceous earth at an irradiation dose of 160 kGy.

FIG. 16 shows the relationship between stress and elongation of irradiated PCL.

FIG. 17 shows the relationship between Young's modulus and irradiation dose for each blending ratio of PCL and PCL / diatomaceous earth (wako) blend.

FIG. 18 shows the relationship between Young's modulus and irradiation dose for each blending ratio of PCL and PCL / diatomaceous earth (sigma) blend.

FIG. 19: PCL / PCL / diatomaceous earth (wako, s
igma) shows the relationship between cutting strength and irradiation dose of the blend.

FIG. 20: PCL / PCL / diatomaceous earth (wak) with each mixing ratio of 20%
o, sigma) shows the relationship between the elongation at break and the dose of the blend.

FIG. 21 is a plot of the relationship between melt viscosity and shear stress for each shear rate of PCL for each dose.

FIG. 22 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 0 kGy with respect to the diatomaceous earth blending ratio of the PCL / diatomaceous earth (wako) blend.

FIG. 23 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 30 kGy with respect to the diatomite compounding ratio of PCL / diatomaceous earth (wako).

FIG. 24 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 50 kGy with respect to the mixing ratio of wako diatomaceous earth.

FIG. 25 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 100 kGy with respect to the diatomaceous earth compounding ratio of PCL / diatomaceous earth (wako).

FIG. 26 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 160 kGy with respect to the diatomite compounding ratio of PCL / diatomaceous earth (wako).

FIG. 27 is a plot of the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 0 kGy with respect to the diatomite compounding ratio of PCL / diatomaceous earth (sigma).

FIG. 28 shows the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 30 kGy by PCL / diatomaceous earth (sigma).
2 is a plot of the diatomaceous earth compounding ratio.

FIG. 29 shows the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 50 kGy by PCL / diatomaceous earth (sigma).
2 is a plot of the diatomaceous earth compounding ratio.

FIG. 30 shows the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 100 kGy by PCL / diatomaceous earth (sigma).
2 is a plot of the diatomaceous earth compounding ratio.

FIG. 31 shows the relationship between melt viscosity and shear stress for each shear rate at an irradiation dose of 160 kGy by PCL / diatomaceous earth (sigma).
2 is a plot of the diatomaceous earth compounding ratio.

FIG. 32 shows the measurement results of the melt viscosity with respect to the angular velocity for a sample having a loading of 20% of the PCL and the PCL / diatomaceous earth (wako and sigma) blend.

FIG. 33 shows shear elastic modulus versus angular velocity per unit time for each irradiation amount at a measurement temperature of 150 ° C. using PCL alone, a PCL / diatomaceous earth (wako) 20% blend, and a PCL / diatomaceous earth (sigma) 20% blend as samples. The measurement results are shown.

FIG. 34 shows the measurement results of elongational viscosity versus angular velocity of a sample in which the irradiation dose of a blend of PCL and 20% diatomaceous earth is 0 kGy.

FIG. 35 shows the measurement results of elongational viscosity versus angular velocity of a sample in which the irradiation dose of a blend of PCL and 20% diatomaceous earth was 30 kGy.

FIG. 36 shows the measurement results of elongational viscosity with respect to angular velocity of a sample at an irradiation dose of 50 kGy in a case of blending 20% diatomaceous earth with PCL.

FIG. 37 shows the measurement results of the dynamic elastic modulus for each irradiation dose of PCL.

FIG. 38 shows a measurement result of a dynamic elastic modulus of a 20% diatomaceous earth sample of a PCL / diatomaceous earth (sigma) blend.

FIG. 39 shows the results of measuring the dynamic modulus of a 20% diatomaceous earth sample of a PCL / diatomaceous earth (wako) blend.

FIG. 40 shows measurement results of weight loss for each irradiation dose of PCL.

FIG. 41 shows the measurement results of weight loss with respect to the blending ratio of a PCL / diatomaceous earth (wako) blend without irradiation.

FIG. 42 shows the measurement results of weight loss with respect to the blending ratio of the PCL / diatomaceous earth (sigma) blend at the time of final irradiation.

FIG. 43 shows the measurement results of weight loss with respect to the blending ratio of PCL / diatomaceous earth (wako) blend at an irradiation dose of 160 kGy.

FIG. 44 shows the measurement results of weight loss with respect to the blending ratio of a PCL / diatomaceous earth (sigma) blend at an irradiation dose of 160 kGy.

FIG. 45 shows the results of measuring the weight loss for each irradiation dose at a diatomaceous earth loading of 20% of the PCL / diatomaceous earth (wako) blend.

FIG. 46 shows the measurement results of weight loss for each irradiation dose at a diatomaceous earth blending ratio of 20% of a CL / diatomaceous earth (sigma) blend.

FIG. 47 shows SEM images of a sample not irradiated with PCL and irradiated with 160 kGy before decomposition, and 12 hours and 24 hours after decomposition.

FIG. 48: PCL / diatomaceous earth (wako) blend ratio of 5%
It is an SEM image in.

FIG. 49: 20% blending ratio of PCL / diatomaceous earth (wako) blend
It is an SEM image in.

FIG. 50: Compounding ratio of PCL / diatomaceous earth (sigma) blend 5
Image by SEM in%.

FIG. 51. Blending ratio of PCL / diatomaceous earth (sigma) blend 20
5 is an image by SEM in%.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C08J 3/28 CFD C08J 3/28 CFD 4G075 5/18 CFD 5/18 CFD 4J002 7/00 302 7/00 302 C08K 3/34 C08K 3/34 C08L 67/04 C08L 67/04 // B29K 67:00 ZBP B29K 67:00 ZBP B29L 7:00 ZBP B29L 7:00 ZBP F term (reference) 2B024 DB01 4F070 AA47 AB09 AC22 AE01 AE30 GA04 GC02 HA02 HA03 HA04 HB01 HB05 HB07 HB10 HB12 HB14 4F071 AA43 AA44 AB30 AF52 AG14 AG15 AH01 BA01 BB06 BB09 BC01 4F073 AA05 BA23 BA47 BA52 BB01 CA41 CA42 CA45 HA11 HA14 4A207 ABA AB01 AB14 AB05 AB01 AB14 KA17 KA19 KL63 KW41 4G075 AA32 BA05 CA38 CA39 CA65 FC20 4J002 CF031 CF131 CF181 CF191 DJ036 FD020 FD060 FD170 FD200 GA01

Claims (8)

[Claims] 1. A resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c), which has been subjected to a radiation irradiation treatment. A biodegradable agricultural multi-film formed by molding. 2. The polylactone (b) is selected from the group consisting of ε-caprolactone, 4-methylcaprolactone, 3,5,5-trimethylcaprolactone, 3,3,5-trimethylcaprolactone, β-propiolactone, γ-butyrolactone, and δ-caprolactone.
The biodegradable agricultural multi-film according to claim 1, which is a homopolymer of valerolactone or enantholactone, a copolymer of two or more of these monomers, or a mixture of these homopolymers or copolymers. 3. The biodegradable agricultural multi-film according to claim 1, wherein the polylactone (b) is poly-ε-caprolactone. 4. The radiation treatment according to claim 1, wherein the radiation treatment is γ-ray or electron beam irradiation by an electron accelerator.
A biodegradable agricultural multi-film according to any one of the above. 5. An aliphatic polyester resin composition obtained by subjecting a resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c) to radiation irradiation treatment. The method for producing a biodegradable agricultural multi-film according to any one of claims 1 to 4, wherein: 6. An aliphatic polyester resin composition obtained by subjecting a resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c) to radiation irradiation treatment. 5. Extruding a tubular film from an annular die into a tubular film, blowing a gas into the tubular film, expanding the tubular film by the pressure of the gas, and then folding the tubular film by nip rolls. A method for producing a biodegradable agricultural multi-film according to the above. 7. A resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c), and the obtained film is irradiated with radiation. The method for producing a biodegradable agricultural multi-film according to any one of claims 1 to 4. 8. A resin composition comprising a dehydration-condensation type aliphatic polyester resin (a) and / or polylactone (b) and diatomaceous earth (c) is extruded from an annular die into a tubular film. Inject gas into
The biodegradable agricultural multi-film according to any one of claims 1 to 4, wherein the tubular film is expanded by the pressure of the gas, then folded by nip roll, and the obtained film is irradiated with radiation. Production method.