JPH11275986A - Degradable mulch film for agriculture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject mulch film having improved shapability and practicality, having a proper strength capable of being plowed in after used for a prescribed period and having the same or larger biodegradability as or than those of conventional films in soil by subjecting a specific component to a radiation irradiation treatment to improve heat resistance. SOLUTION: This mulch film for agriculture is produced by shaping a lactone resin alone or a composition comprising the lactone resin and one or more other biodegradable resins. The lactone resin as the component of the mulch film for agriculture singly or together with at least one other component is subjected to a radiation irradiation treatment. Therein, the other biodegradable resin is preferably a synthetic polymer such as an aliphatic polyester and/or a natural polymer such as starch. A lactone resin/synthetic polyester resin weight ratio is preferably 5/95 to 70/30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lactone-containing resin comprising a specific radiation-treated lactone resin alone or a lactone resin and another biodegradable resin.
Or, it relates to a degradable agricultural multi-film formed by molding a lactone-containing resin composition comprising the lactone-containing resin and a resin additive.

[0002]

2. Description of the Related Art Agricultural multi-films or sheets (hereinafter sometimes referred to as agricultural multi-films or multi-films) are used for controlling the drastic change of soil temperature, suppressing the growth of weeds,
It is used for the purpose of improving the yield of crops by the action of sustained release of nutrients. 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 colored black, silver, white, etc. 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, and there is only a method of incineration when discarding it. However, there is a new problem such as a risk of damage to the incinerator caused by plastic.

[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 microorganism is completely decomposed by microorganisms in the soil. 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 biochemically decomposed 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 predetermined use period can be relatively easily changed, it is suitable as an agricultural multi-film. Here, the biodegradable resin does not exhibit biodegradability almost in the same way as general-purpose plastics when used as an agricultural multi-film, but when it is buried in activated sludge, soil, compost, etc. after disposal Refers to a polymer compound that is rapidly degraded biochemically by microorganisms such as bacteria and mold, and in some cases, to carbon dioxide and water.

Conventionally, as a biodegradable resin, starch, EVOH (ethylene-vinyl alcohol copolymer) resin, EVOH resin, besides a specific polyester-based biodegradable resin in order to satisfy the above requirements. Blend-based resin compositions such as aliphatic polyester-based resins and aliphatic polyester-based resins-polyolefin-based resins are known, and these resins or resin compositions can be formed into various films for the time being. When viewed as, the moldability required at the time of film production, mold resistance required for the multi-film, weather resistance and other physical properties, in all aspects such as biochemical degradability required after disposal A well-balanced and excellent resin or resin composition has not yet been proposed.

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. According to the gazette, a lubricant is used in an amount of 0.3 to 0.1% by weight based on 100 parts by weight of a mixture of 80 to 100% by weight of polycaprolactone and 20 to 0% by weight of a biodegradable linear polyester resin produced by living organisms.
A biodegradable plastic film formed from a composition containing 8 parts by weight is disclosed. However, in the former case, EVOH with low biodegradability is used, and it contains starch as an essential component, which is liable to generate mold and is hard to withstand outdoor use, and is not necessarily suitable as an agricultural multi-film. . The film disclosed in the latter has problems in mechanical strength at the time of molding and its productivity, and is slow in biochemical decomposition, and is not necessarily suitable as a multi-film.

Further, JP-A-9-235360 and 9-235
No. 233956 discloses an aliphatic oxycarboxylic acid unit (R ¹ is a divalent aliphatic hydrocarbon group) represented by (1) —O—R ¹ —CO—, (2) —O—R 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 Agricultural films such as agricultural multi-films using an aliphatic polyester-based copolymer having a direct bond or a divalent aliphatic hydrocarbon group and having a predetermined molecular weight have been proposed. Is not specified, and there is a problem in the supply of raw material resin itself that requires stable film characteristics.

Japanese Unexamined Patent Publication (Kokai) No. 7-177826 discloses an agricultural film containing a 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, a stretched film for increasing strength is suitable, and is not necessarily preferable as an agricultural film requiring easy mass production and versatility.

On the other hand, a lactone resin such as polycaprolactone is a biodegradable resin. Although it is an environment-friendly resin, polycaprolactone has a relatively low melting point of, for example, 60 ° C. or more. However, there is a limit in the practicality as a multi-film, and it cannot be used immediately as an agricultural multi-film.

[0009]

Accordingly, an object of the present invention is to overcome the problems of moldability and practicality (strength, etc.) based on the low melting point of the lactone resin while utilizing the good biodegradability of the lactone resin. An object of the present invention is to find a means and obtain an excellent agricultural multi-film containing a lactone resin. More specifically, the heat resistance is improved to improve the formability and practicality, and after using the agricultural multi-film for a predetermined period of time, it shows an appropriate strength that can be plowed, and in the soil, it is the same as the conventional one, Another object of the present invention is to provide an agricultural multi-film having superior biodegradability.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, a lactone resin alone, a biodegradable resin composition containing a lactone resin in advance, or a film using the same. By performing irradiation treatment under specific conditions at the stage of molding, the knowledge of obtaining a film suitable for solving the problem was obtained, and the present invention was completed. That is, the gist of the present invention is as follows.

A first aspect of the present invention is an agricultural multi-film formed by molding a lactone resin alone or a composition of a lactone resin and another biodegradable resin, and a component lactone resin of the agricultural multi-film. Provides a degradable agricultural multi-film, which has been subjected to radiation irradiation alone or together with at least one other component. A second aspect of the present invention provides the degradable agricultural multi-film according to the first aspect, wherein the other biodegradable resin is a synthetic and / or natural polymer. A third aspect of the present invention provides the degradable agricultural multi-film according to the second aspect of the present invention, wherein the synthetic polymer comprises an aliphatic polyester, a biodegradable cellulose ester, a polypeptide, a polyvinyl alcohol, or a mixture thereof. I do. A fourth aspect of the present invention is the decomposition method according to the second aspect, wherein the natural polymer comprises starch, cellulose, paper, pulp, carrageenan, chitin / chitosan, natural linear polyester resin, or a mixture thereof. Provide multi-films for sexual agriculture. The fifth of the present invention
Furthermore, photodegradation, biodegradation accelerators, fine powder particles made from paper, plasticizers, heat stabilizers, extenders, fillers, lubricants, colorants, flame retardants, water resistance agents, autoxidants, ultraviolet rays Stabilizer,
Add a crosslinking agent, an antibacterial agent, a fungicide, a herbicide, an antioxidant, a deodorant, a nucleating agent, an antiblocking agent, a dropping agent, an antifogging agent, an antifog agent, an antistatic agent or a mixture thereof. A degradable agricultural multi-film according to the first or second aspect of the present invention is provided. The sixth aspect of the present invention is an agricultural multi-film formed by molding a resin composition containing a lactone resin, a synthetic aliphatic polyester resin and a fatty acid amide, wherein the constituent lactone resin of the agricultural multi-film is used alone or A degradable agricultural multi-film, which has been subjected to a radiation irradiation treatment together with at least one other component. According to a seventh aspect of the present invention, there is provided the degradable agricultural multi-film according to the sixth aspect, wherein the ratio of the fatty acid amide to the total of 100 parts by weight of the lactone resin and the synthetic aliphatic polyester resin is 0.2 to 5 parts by weight. provide. An eighth aspect of the present invention provides the degradable agricultural multi-film according to any one of the sixth to seventh aspects of the present invention, wherein the weight ratio of the lactone resin / the synthetic aliphatic polyester resin is 5/95 to 70/30. . A ninth aspect of the present invention is the sixth aspect of the present invention, which further comprises 0.1 to 3 parts by weight of a liquid lubricant based on 100 parts by weight of the total of the lactone resin and the synthetic aliphatic polyester resin.
The present invention provides a degradable agricultural multi-film according to any one of the above-described items. A tenth aspect of the present invention is the sixth to ninth aspects of the present invention further including 0.1 to 3 parts by weight of finely divided silica with respect to a total of 100 parts by weight of the lactone resin and the synthetic aliphatic polyester resin.
The present invention provides the degradable agricultural multi-film according to any one of the above. An eleventh aspect of the present invention is the degradable agricultural use according to any one of the sixth to tenth aspects of the present invention, which further includes 10 to 80 parts by weight of starch based on 100 parts by weight of the total of the lactone resin and the synthetic aliphatic polyester resin. Provide multi-film. A twelfth aspect of the present invention provides the degradable agricultural multi-film according to any one of the first to eleventh aspects, wherein the lactone resin is poly-ε-caprolactone. A thirteenth aspect of the present invention provides the degradable agricultural multi-film according to any one of the first to twelfth aspects of the present invention, wherein the acrylic resin is coated on at least one side of the surface.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The lactone resin used in the present invention is ε-caprolactone, 4-methylcaprolactone, 3,5,5-
Various methylated caprolactones such as trimethylcaprolactone, 3,3,5-trimethylcaprolactone, β-
Examples include homopolymers such as propiolactone, γ-butyrolactone, δ-valerolactone, and enantholactone, copolymers of two or more of these monomers, and mixtures of these homopolymers or copolymers. The lactone resin may be copolymerized with a lactone monomer and a monomer other than the lactone monomer, for example, an aliphatic hydroxycarboxylic acid such as lactic acid, hydroxypropionic acid, hydroxybutyric acid;
Examples thereof include aliphatic diols and aliphatic dicarboxylic acids exemplified by the aliphatic polyester described below. In particular, those which do not soften at room temperature are preferable, and from this viewpoint, a polymer having a high molecular weight and a melting point of 60 ° C. or more, which is easy to obtain stable performance.
ε-caprolactone (hereinafter sometimes referred to as PCL or polycaprolactone) is preferred. Hereinafter, the lactone resin according to the present invention will be described using polycaprolactone as a typical example. As polycaprolactone,
The number average molecular weight is preferably 10,000 to 1,000,000, but 100,000 to 50 from the viewpoint of efficient crosslinking.
Particularly preferred are those having a molecular weight of 10,000. The polycaprolactone having the above-mentioned 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.

The biodegradable resin composition used in the present invention contains a lactone resin and another biodegradable resin. The other biodegradable resin is not particularly limited as long as it is a resin that can be mixed with a lactone resin and formed into a target multi-film as a composition, and various known resins are used. Preferred examples of such a biodegradable resin include aliphatic polyesters (to be further exemplified later), biodegradable cellulose esters, polypeptides, and starch (to be further exemplified later). These can be used alone or in combination of two or more. 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, and cellulose acetate phthalate. And mixed esters such as cellulose nitrate acetate. 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 and polyamide esters. As such a biodegradable resin composition,
Preferably, it is obtained by adding a synthetic aliphatic polyester resin to a lactone resin, and furthermore, is obtained by adding a fatty acid amide. Hereinafter, the present invention will be described by taking a composition obtained by adding a synthetic aliphatic polyester resin and a fatty acid amide to a lactone resin as an example, but when the lactone resin is used alone, the composition of the lactone resin and another biodegradable resin is used. The same applies to objects.

[0014] As a preferred example of the present invention, in an agricultural multi-film formed by molding a biodegradable resin composition comprising a lactone resin, a synthetic aliphatic polyester resin and a fatty acid amide, at least the lactone constituting the agricultural multi-film. The resin has been subjected to a predetermined radiation irradiation treatment. Therefore, as the resin composition used in the present invention, the lactone resin alone is subjected to a predetermined irradiation treatment in advance, and a resin composition obtained by adding a synthetic aliphatic polyester resin and a fatty acid amide thereto, as well as a lactone resin. The above-mentioned irradiation is performed by mixing a synthetic aliphatic polyester resin or a fatty acid amide and subjecting the same radiation irradiation treatment to a resin composition obtained by mixing the remaining components, a lactone resin, a synthetic aliphatic polyester resin and a fatty acid amide. A resin composition obtained by the treatment is also included. Further, as a mode of performing irradiation treatment by mixing these three components, in addition to a mode of irradiating a composition as a forming raw material (eg, pellets or a strand after kneading for pellet production), a composition being formed is irradiated with a composition. Also included are embodiments. In order to improve the biodegradability of the molded product, it is preferable to mold using a resin composition containing a lactone resin obtained by irradiation treatment, for example, pellets.

The above-mentioned biodegradable resin composition used in the present invention may further contain a liquid lubricant, finely divided silica and / or starch, and a predetermined irradiation treatment may be carried out after these additions. Is also good. Similarly, the biodegradable resin composition of the present invention may contain a plasticizer, a photodegradation accelerator, and a biodegradation accelerator.

The synthetic aliphatic polyester resin used in the present invention is a polyester resin other than a lactone resin, and is an aliphatic polyester resin obtained by a condensation polymerization system. Hereinafter, the synthetic aliphatic polyester resin is simply referred to as an aliphatic polyester resin, and in the case of a naturally occurring resin, this is clearly indicated. Examples of the aliphatic polyester resin include biodegradable polyester resins such as synthetic polylactic acid, polyethylene succinate, and polybutylene succinate (such resins include low molecular weight aliphatic resins represented by Bionole of Showa Polymer Co., Ltd.). Examples thereof include polyester resins synthesized from dicarboxylic acids and low molecular weight aliphatic diols).
Aliphatic polyesters of terpolymers described in JP-A-5360 and 9-2333956, JP-A-7-177826
Lactic acid and hydroxycarboxylic acid copolymer described in
A polyamide ester resin and a polyamino acid resin synthesized from -caprolactone and ε-caprolactam. As the aliphatic polyester resin, those having a number average molecular weight of 20,000 to 200,000, preferably 40,000 or more in terms of standard polystyrene by GPC can be used. As the aliphatic polyester resin,
It is also possible to add an aliphatic diisocyanate such as hexamethylene diisocyanate to a low molecular weight aliphatic polyester resin to introduce a urethane bond to increase the molecular weight.

As one component fatty acid amide of the biodegradable resin composition according to the present invention, lauric amide, palmitic amide, high-purity palmitic amide, stearic amide, purified stearic amide, high-purity stearic amide, Saturated fatty acid monoamides such as behenic acid amide, high-purity behenic acid amide, hydroxystearic acid amide and oleic acid amide; methylene bisstearic acid amide;
Ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylenebisisostearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid amide Saturated fatty acid bisamides such as hexamethylene bishydroxystearic acid amide, N, N'-distearyl adipamide, N, N'-distearyl sebacic acid amide; oleic acid amide, purified oleic acid amide, purified erucic acid amide , Unsaturated fatty acid monoamides such as ricinoleamide; ethylenebisoleamide, hexamethylenebisoleamide,
Unsaturated fatty acid bisamides such as N, N'-dioleyl adipamide, N, N'-dioleyl sebacamide; N-stearyl stearamide, N-oleyl oleamide, N-stearyl oleamide;
Substituted amides such as N-oleyl stearamide, N-stearyl erucamide, N-oleyl palmitamide; methylol stearamide; methylol amides such as methylol behenamide; N, N-distearyl isophthalate Fatty acid amides such as aromatic bisamides such as acid amide and meta-xylylene bisstearic acid amide. These are solid lubricants at room temperature.

Among the above fatty acid amides, ethylene bisstearic acid which is highly safe and is registered with the FDA (US Food and Drug Administration) from the viewpoint of preventing environmental pollution by the agricultural multi-film according to the present invention. Amides, stearamides, oleamides, and erucamides are preferred.

When an appropriate fatty acid amide is selected from the above fatty acid amides according to the present invention, it is, of course, necessary to select a fatty acid amide having a melting point lower than the melting point of various aliphatic polyester resins to be blended. . For example,
In consideration of the melting point of the synthetic aliphatic polyester resin, a fatty acid amide of 160 ° C. or lower is selected as the fatty acid amide.

In the radiation irradiation treatment according to the present invention, a powdery or pelletized lactone resin alone, a composition comprising a lactone resin and a synthetic aliphatic polyester resin, and a composition comprising a lactone resin and a fatty acid amide, according to the conditions described later. , A lactone resin, a synthetic aliphatic polyester resin and a fatty acid amide. In addition, in the case of these compositions, a simple mixture of each component in the form of powder or pellets may be used, but a mixture obtained by appropriately kneading the mixture is more preferably powdered or pelletized. Further, the irradiation treatment may be performed during the formation of the multi-film so as to satisfy the condition regarding the temperature of the lactone resin at the time of the irradiation treatment described later.

In the present invention, the lactone-containing resin has been subjected to a predetermined radiation irradiation treatment. Gel fraction is 0.01
By irradiating so as to be 10 to 10%, preferably 0.05 to 5.0%, crosslinking occurs and the melting point increases,
The tensile strength and the tear strength are improved, the releasability from the mold and the roll adhesion are reduced, and the transparency is increased. In addition, a mode in which irradiation is performed at a low dose first and then a high dose is performed at a later stage is also included. For example, the gel fraction is 0.01 to 10 in the pellet stage.
%, Preferably 0.05 to 5.0%, and 5 to 90% during molding or after molding, preferably 10 to 9%.
Irradiation can be performed so as to be 0%. This allows
Since the melt viscosity is higher than that of the unirradiated material, it is possible to maintain the shape at a higher temperature and irradiate again, and the crosslinking occurs with a high probability and the heat resistance is improved.

The radiation irradiation treatment according to the present invention is not limited to a temperature but may be room temperature. However, the lactone resin powder or pellet is melted at a temperature not lower than the melting point (60 ° C. for PCL) and does not lead to crystallization after melting (50 ° C. for PCL). (-35 ° C.). By performing the above treatment in this state, a gel with a very high gel fraction can be obtained at a low dose. The term “does not lead to crystallization” as used herein refers to a state in which the non-crystalline state is dominant because cross-linking occurs in the non-crystalline part, although it cannot be accurately specified. If the degree of crystallinity is lower than in the room temperature state, there is a corresponding irradiation effect. In addition, not only the treatment with the lactone resin alone, but also the treatment with the above various compositions comprising other components, it is sufficient to consider only the molten state of the lactone resin component.

The radiation source used in the radiation irradiation treatment according to the present invention includes 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, the γ-rays or electron beam irradiation treatment using an electron accelerator can be used to introduce a crosslinked structure of a polymer material. Is the most convenient.

In the crosslinking reaction, which is the effect of radiation treatment of the lactone resin in the present invention, the degree of crosslinking increases as the dose increases. The dose rate of the radiation is not particularly limited, but a higher dose rate is preferable because the production efficiency is improved. The atmosphere at the time of the radiation treatment is not particularly limited, but it is advantageous that the lower the oxygen concentration, the smaller the irradiation dose.

The preferred mixing ratio of each component constituting the biodegradable resin composition according to the present invention will be described. First, the compounding ratio of the lactone resin to the aliphatic polyester resin is preferably 30 to 95% by weight of the former (70 to 5% by weight) (total 100% by weight of both), but in this case, the upper limit of the former is 60%. It is particularly preferred that the content is not more than 40% by weight, and the range of 60 to 90% by weight of the latter is more preferable than 40 to 10% by weight of the former. In this case, if the lactone resin exceeds 70% by weight, the mechanical properties at high temperature of a molded product such as a film tend to decrease, and if it is less than 5% by weight, disintegration based on biochemical decomposition may decrease. This tendency is 40 ~
The same can be said for a case outside the range of 10% by weight. On the other hand, if the amount of the aliphatic polyester resin exceeds 95% by weight, the biodegradability tends to be slow.
When the amount is less than the weight percentage, for example, when processed into a film, heat resistance may be reduced. The same can be said for the case where this tendency is out of the range of 60 to 90% by weight.

The mixing ratio of the fatty acid amide is preferably from 0.2 to 5 parts by weight, more preferably from 0.3 to 1.5 parts by weight, based on 100 parts by weight of the total of the lactone resin and the aliphatic polyester resin. preferable. If the fatty acid amide is less than 0.2 parts by weight, the effect of preventing blocking of the film molded product is slightly lowered, while if it exceeds 5 parts by weight, the slipperiness of the film tends to be higher than necessary, and the printability, adhesiveness, etc. Also begin to show a downward trend.

The melt fluidity of the biodegradable resin composition comprising a lactone resin, an aliphatic polyester resin and a fatty acid amide, which has been subjected to the above-mentioned specific irradiation treatment according to the present invention, is as follows:
The resin composition is not particularly limited as long as the resin composition can be used for film forming. However, for forming an agricultural multi-film, a melt flow index (MI) (190 ° C.)
Measured at a load of 2160 g) at 0.5 to 20 g / 1.
0 min, preferably 1 to 5 g / 10 m
in is suitable.

To the biodegradable resin composition according to the present invention, a liquid lubricant, fine powder silica, starch and the like are further added as required. The purpose of use of the liquid lubricant is that the lactone resin or the aliphatic polyester resin as the resin component constituting the resin composition is usually supplied in the form of pellets or beads as described above, and the fine powder having an extremely small bulk specific gravity as described below. This is because, in order to uniformly mix silica and the like, it is preferable to keep the surfaces of the pellets and beads as wet as possible. The 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 0.1 part by weight, based on 100 parts by weight of the total amount of the lactone resin and the aliphatic polyester resin. It is added in the range of 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 mixing tumbler, 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 also observed outside the more preferred range of 0.2 to 0.7 parts by weight.

Accordingly, the liquid lubricant as a wetting agent preferably has a melting point of 70 ° C. or lower, and more preferably a liquid lubricant at room temperature. For example, in addition to liquid paraffin, paraffin wax, stearyl alcohol, stearic acid, etc., stearic esters such as butyl stearate, monoglyceride stearate, pentaerythritol tetrastearate, stearyl stearate and the like can be mentioned.

The most preferred liquid paraffin among the above liquid lubricants has an oral acute toxicity (rat) LD50 of 5 g / k.
g, it is very safe, is recognized as a food additive under the Food Sanitation Act, and is a very convenient material in terms of preventing environmental pollution when the multi-film is discarded. 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 blocking of the agricultural multi-film according to the present invention. The fine powdered silica used may be silica produced by a wet method, silica produced by high-temperature hydrolysis of silicon tetrachloride in an oxyhydrogen flame, and the like, particularly those having a particle size of 50 nm or less. Is preferred. As the addition method, the method of heating and kneading a resin composition containing the lactone resin according to the present invention, a composition comprising a lactone resin and an aliphatic polyester resin or a resin composition further adding a fatty acid amide is most preferable. A considerably high shearing force acts to loosen the secondary aggregated particles, thereby exhibiting a multi-film anti-blocking effect. In addition, the addition amount of the fine powder silica,
Mixture 10 of lactone resin and aliphatic polyester resin
The range of 0.1 to 3 parts by weight with respect to 0 parts by weight is most preferable in terms of exhibiting the above effects.

Various starches are added to the resin composition according to the present invention. The amount of starch added is not particularly limited, but is preferably from 10 to 80 parts by weight based on 100 parts by weight of the total amount of the lactone resin and the aliphatic polyester resin in order to effectively achieve degradability. The range of 25 to 50 parts by weight is particularly preferred.

The starch that can be used for the above purpose includes
Raw starch, processed starch and mixtures thereof are included. Examples of the raw starch include corn starch, horse bell chopsticks starch, sweet potato starch, wheat starch, cassava starch, sago starch, tapioca starch, rice starch, legume starch, kuzu starch, bracken starch, lotus starch, and heishi starch. Examples of the starch include physically modified starch (α-starch, fractionated amylose, wet heat-treated starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzyme-decomposed dextrin, amylose, etc.), chemically-modified starch (acid-treated starch, hypochlorite). Acid-oxidized starch, dialdehyde starch, etc.) and chemically modified starch derivatives (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 starch such as allyl etherified starch, methyl etherified starch, carboxymethyl etherified starch, hydroxyethyl etherified starch and hydroxypropyl etherified starch; etc .; cationized starch includes starch and 2-diethylaminoethyl chloride , A reaction product of starch and 2,3-epoxypropyltrimethylammonium chloride, etc .; Examples of the crosslinked starch include formaldehyde crosslinked starch, epichlorohydrin crosslinked starch, phosphoric acid crosslinked starch, and acrolein crosslinked starch.

The photodegradable or biodegradable accelerator, a lactone resin as a component of the resin composition, and an aliphatic resin may be added to the biodegradable resin composition or the composition further containing the various additives. Resin components other than polyester resin (for example, ethylene copolymer and other polyolefins, hydrogenated styrene butadiene rubber, polyurethane, polyamide, polyhydroxybutyrate, etc.), and natural polymers other than the above-mentioned starch (for example, polysaccharide-based polymers) Molecules, cellulose-based polymers, protein-based polymers, etc.), fine powder particles produced from paper having a diameter of 50 microns or less, plasticizers, heat stabilizers, extenders, fillers such as calcium carbonate, lubricants, and colorants. , Resin additives such as flame retardant, water resistant agent, autoxidizer, UV stabilizer, crosslinking agent, antibacterial agent, herbicide, antioxidant, deodorant, antistatic agent It can be. Urea, alkaline earths, alkali metal hydroxides and mixtures thereof can also be added as starch modifiers. In particular, the addition of a photodegradation accelerator, an autoxidizer, or the like is a preferred method for imparting brittleness to the film around a desired period of time that functions as a multi-film, thereby facilitating plowing.

Examples of the photodegradation accelerator include benzophenones such as benzoins, benzoin alkyl ethers, benzophenone and 4,4-bis (dimethylamino) benzophenone and derivatives thereof; acetophenone,
Acetophenones such as α, α-diethoxyacetophenone and derivatives thereof; quinones; thioxanthones; photoexciting materials such as phthalocyanine, anatase-type titanium oxide, ethylene-carbon oxide copolymer, sensitization of aromatic ketones with metal salts And the like. These photolysis accelerators are
One type or two or more types 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) and saturated dicarboxylic acids (for example, Organic acids such as lower saturated dicarboxylic acids having about 2 to 6 carbon atoms such as oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid and the like; these organic acids and alcohols having about 1 to 4 carbon atoms; Lower alkyl esters. Preferred biodegradation promoters include organic acids having about 2 to 6 carbon atoms, such as citric acid, tartaric acid, and malic acid, and coconut shell activated carbon. One or more of these biodegradation accelerators can be used in combination.

As a method of 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. For example, to describe an example of a method for producing the above composition, first, a lactone resin and an aliphatic polyester resin and a liquid lubricant are placed in a tumbler, and
Then, the fatty acid amide is added, and the fine powder silica and starch are added thereto, and the mixture is further stirred and mixed for 20 to 30 minutes. After that, a 14 or single screw extruder or the like is used.
Melt kneading is performed at about 0 to 210 ° C. to obtain powder or pellets of the resin composition containing various additives.

The powdery or pelletized additive-containing resin composition obtained in this manner has a higher melting point than that of a conventional lactone resin without irradiation treatment or its composition, which is considered to be based on its crosslinked structure. By increasing the viscosity, the film is formed into a film by various conventional forming methods such as an inflation method and a T-die method. For example, a method of forming a film by an inflation method is described below. First, it is supplied to an extruder equipped with an annular die, melt-kneaded at a temperature of 180 ° C., and extruded into a tube from an annular die slit. For example, the extrusion diameter of the extruder at this time is about 40 to 65 mm, the length / diameter ratio (L / D) is 26 to 32, and the diameter of the annular die is 50 to 150 mm.
The die slit gap is 0.5 ~
A range of 1.5 mm is preferred. The extruded tube-shaped film has a blow ratio (tube diameter / tube diameter) depending on the pressure of gas introduced from a gas blowing pipe inserted through the die.
Die diameter) is set to 2 or more, expanded to a predetermined diameter, then folded by a nip roll and taken off at a constant speed, a tubular film is obtained, cut in the take-off direction, and a unit weight suitable for an agricultural multi-film. Although a wide film may be obtained, it is usually more efficient to make a wide film immediately by making a similar incision at the time of exiting the nip roll.
The resin composition or various additive-containing resin compositions obtained through the radiation treatment step according to the present invention can stably form a film under 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, when a cold air of 20 ° C. or less is introduced from the gas blowing pipe, a film with no blocking is obtained more completely. The same applies to the case where the film being formed is irradiated with radiation.

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 and the plant to be cultivated. The thickness which can be generally used and can obtain a crosslinking effect by irradiation with radiation is preferably 10 μm to 1 mm, more preferably 50 μm to 500 μm. The film may have a multilayer structure depending on the purpose, or an acrylic resin may be coated on one or both surfaces of the film. Thereby, weather resistance, stain resistance, abrasion resistance, heat retention, moisture retention, anti-fogging properties, anti-fog properties, dropping properties, etc. can be improved. Examples of the acrylic resin include acrylic resins composed of methyl (meth) acrylate, alkyl (meth) acrylate having 2 to 4 carbon atoms, hydroxyethyl (meth) acrylate, and a mixture thereof, which are formed into an emulsion and coated on a film. 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 in if necessary, and then placed in a biodegradable environment. .

[0041]

EXAMPLES The present invention will now be described specifically 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. Melt index (MI)
Is a value indicating the flow characteristics at a load of 2160 g at 190 ° C.

REFERENCE EXAMPLE 1 Polycaprolactone pellets (melt index: 2.57 g / 10 min) were heated to a melting point or higher, then cooled to 50 ° C., and while being in an amorphous state, an electron beam was irradiated with 60 kGy and 160 kGy as radiation. Upon irradiation, the resulting treated pellets had a melt index of 0.05 g / 10 min (gel fraction 60 described below).
%) And 0.03 g / 10 min (gel fraction 80%). The untreated pellets and treated pellets were placed in an urban sewage sludge environment at 25 ° C. according to JIS K6950,
They were subjected to a 4-week biodegradability test. As a result, the decomposition rate of the non-irradiated product was 55%, while that of the irradiated product was 86.2% and 77.2%, respectively. Further, the irradiated product was formed into a sheet by a hot press at 200 ° C., and a biodegradability test was similarly performed on the pulverized sample. as a result,
The decomposition rates were 87.0% and 87.8%, respectively. The same test results were obtained by changing the irradiation type from electron beam to gamma ray.

Reference Example 2 The polycaprolactone used in Reference Example 1 was irradiated with an electron beam at a dose of 15 kGy at room temperature. Processed pellets (melt index is 1.0
g / 10 min, gel fraction 0.2%) was extruded with an extruder (resin temperature 150 ° C.) provided with a 40 mmφ T-die to obtain a sheet having a thickness of about 270 μm. The obtained sheet was subjected to a tear test, an impact strength test according to JIS K7211 and a tensile test according to JIS K6782 at room temperature, and compared with the test results of unirradiated products similarly formed into sheets. As a result, the tensile strength (MD: longitudinal direction) was 260, 280 kgf in the order of the unirradiated product and the irradiated product.
・ Cm, the lateral direction (TD) is 210, 230kgf ・ c
m, tensile elongation (MD) 1130, 1240%, TD
Is 1130, 1160%, the tear strength (MD) is 160,
270 gf, the TD improved to 190 and 450 gf, and the impact strength test improved to 23.8 and 25.2 kgf · cm, respectively.

Reference Example 3 An electron beam was applied to the polycaprolactone used in Reference Example 1 at room temperature at 10, 20, 40, 10
Irradiation at 0 kGy was performed to measure changes in MI and gel fraction (%), and the following values were obtained in order. Electron beam dose (kGy): 0, 10, 20, 40, 1
00 MI (g / 10 min): 2.6, 1.0, 0.5, 0.1, 0.08 Gel fraction (%): 0, 0.1, 0.2, 0.3, 23.7 In Reference Examples 1 to 3, the biodegradable resin Bionole was added to polycaprolactone. Irradiation was examined for those to which was added, but there was essentially no change.

(Preparation of Biodegradable Resin Composition) Preparation Example 1 Polycaprolactone (Placcel H7, trade name, manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 1.2)
10 g of 8 × 10 ⁵ ) pellets were placed in a 1.5 cm diameter glass ampule, which was connected to a vacuum line to remove air, and then sealed. This sample was completely melted in an oven at 80 ° C., inserted into a metal block adjusted to 45 ° C. in advance, and irradiated with 100 kGy at a dose rate of 10 kGy / hr by gamma rays from cobalt 60. After the irradiation, the glass ampule was opened, and a cylindrical PCL having a diameter of 1.5 cm was taken out. From this, cut out a thin plate about 5mm thick,
It was wrapped in a 200-mesh stainless steel wire gauze, immersed in a chloroform solution for 24 hours, and the gel fraction (the ratio of insolubles, representing the degree of crosslinking) was determined by the following equation.
It was 0%. Gel fraction _{(%) = (W 2 /} W 1) × 100 ( wherein, W ₁ represents the dry weight of the PCL before immersion, W ₂
Represents the dry weight of the insoluble matter after immersion. Further, in order to examine the heat resistance, PCL sliced to a thickness of 2 to 3 mm was compression-molded into a film by hot pressing at 200 ° C., and the obtained film was extremely excellent in transparency. Heat resistance is 100mm / min tensile speed
Using a high temperature tensile tester. The results are shown in Table 1. 40 parts of polycaprolactone, which has been subjected to an irradiation treatment step adjusted to have the same gel fraction as the irradiation, poly 1,
60 parts of 4-butanediol-succinate, 0.5 parts of liquid paraffin, and 1 part of stearamide were put into a twin-screw vented extruder (40 mm diameter),
The resin composition was extruded at a die temperature of 180 ° C. to obtain pellets of the resin composition. The melt index of this resin composition is 0.1 g.
/ 10 min.

[Preparation Example 2] The gel fraction of polycaprolactone obtained through the same process as the irradiation step described in Preparation Example 1 except that irradiation was performed at a dose of 150 kGy with γ-rays was 82%.
Met. Further, a heat resistance test was conducted by the method described in Preparation Example 1, and the results are shown in Table 1. 40 parts of polycaprolactone after the irradiation step, 60 parts of poly 1,4-butanediol-succinate, 0.5 part of liquid paraffin,
Pellets of the resin composition were obtained in the same manner as in Preparation Example 1 using 0.8 parts of stearamide and 0.8 parts of fine powdered silica (“Aerosil # 200” manufactured by Nippon Aerosil Co., Ltd.). The melt index of this resin composition is 0.09 g / 10
min.

[Preparation Example 3] 40 parts of polycaprolactone and poly 1, which had undergone the same irradiation step as described in Preparation Example 2,
Pellets of the resin composition as in Preparation Example 1 using 60 parts of 4-butanediol-succinate, 0.5 parts of liquid paraffin, 0.5 parts of stearamide and 0.5 parts of Aerosil # 200 (same as above). I got The melt index of this resin composition was 0.09 g / 10 min.

[Preparation Example 4] Polycaprolactone (40 parts), which had been subjected to the same step as the irradiation step described in Preparation Example 2,
Same as Preparation Example 1 using 60 parts of 4-butanediol-succinate, 0.5 parts of liquid paraffin, 0.5 parts of stearamide, 0.5 parts of Aerosil # 200 (same as above) and 50 parts of corn starch. Pellets of the resin composition were obtained. The melt index of this resin composition is 0.0
It was 9 g / 10 min.

[Comparative Preparation Example 1] Unirradiated polycaprolactone (40 parts), poly-1,4-butanediol-succinate (60 parts), liquid paraffin (0.5 parts), stearic acid amide (0.8 parts), finely divided silica (Japan Pellets of the resin composition were obtained in the same manner as in Preparation Example 1 using 0.8 parts of "Aerosil # 200" manufactured by Aerosil Co., Ltd. The melt index of this resin composition was 3.9 g / 10 minutes.

(Examples 1 to 4, Comparative Example 1) Preparation Examples 1 to
4. Using the pellets of the resin composition prepared in Comparative Preparation Example 1, an agricultural multi-film having a width of 900 mm was produced by an inflation method under the following molding conditions. (Molding conditions) Extruder: 40 mm diameter extruder Screw: L / D = 28, screw for MDPE (medium density polyethylene) Die: lip diameter 150 mm, die gap 1 mm Extrusion temperature: 170 ° C. at cylinder tip Die temperature: 170 ° C. Resin temperature (T1): 160 ° C. Screw rotation speed: 15 rpm Discharge amount: 15 kg / hr Blow ratio: 2.5 Multi-films obtained from the films using the resin compositions of Preparation Examples 1 to 4 were each prepared in Example 1. 4, and a multi-film obtained from a film using the resin composition of Comparative Preparation Example 1 was used in Comparative Example 1. Specifically, the multi-film is laid on the soil surface in the summertime at a temperature of 20 to 35 ° C. in the daytime, and the damage state of the film after one month and three months is examined. Was examined. One month after the plowing, the occurrence of biodegradability was examined by appearance and touch by hand. As a result, the multi-film according to the present invention did not show tears even after three months of laying, but was easy to plow. In addition, it was found that one month after the plowing, biodegradation was observed by observation and touch by hand. On the other hand, in Comparative Example 1, there was no change even after three months of laying, and furthermore, even after two months, the plowing operation was impossible, and it could not be buried in the soil, and therefore did not biodegrade. .

[0051]

[Table 1]

[0052]

The agricultural multi-film according to the present invention comprises:
It is easy to mold as a radiation treatment effect and has sufficient physical strength, so it fully demonstrates its original function as a multi-film. It was found that the biodegradable material was buried in soil at a speed that was superior to the biodegradability of the multi-film material.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 93/00 C08L 93/00 // C08J 5/18 CFG C08J 5/18 CFG (72) Inventor Hiroshi Mitomo Tenjin, Kiryu-shi, Gunma 1-5-1, Machi, Gunma University Faculty of Engineering (72) Inventor Dharmawan Dalwis 1-5-1, Tenjincho, Kiryu-shi, Gunma Gunma University Faculty of Engineering (72) Inventor Sada Murakami 1-1-1, Shinmatsudo Minami, Matsudo, Chiba 323

Claims (13)

[Claims] 1. An agricultural multi-film formed by molding a lactone resin alone or a composition of a lactone resin and another biodegradable resin, wherein the constituent lactone resin of the agricultural multi-film is used alone or in combination. A degradable agricultural multi-film, which has been subjected to a radiation irradiation treatment together with at least one component of the above. 2. The degradable agricultural multi-film according to claim 1, wherein the other biodegradable resin is a synthetic and / or natural polymer. 3. The degradable agricultural multi-film according to claim 2, wherein the synthetic polymer comprises an aliphatic polyester, a biodegradable cellulose ester, a polypeptide, a polyvinyl alcohol, or a mixture thereof. 4. The natural polymer is starch, cellulose, paper,
The degradable agricultural multi-film according to claim 2, comprising pulp, carrageenan, chitin / chitosan, natural linear polyester resin, or a mixture thereof. 5. Photodegradation, biodegradation accelerators, fine powder particles made from paper, plasticizers, heat stabilizers, extenders, fillers, lubricants, coloring agents, flame retardants, water resistance agents, autoxidation Agents, UV stabilizers, crosslinking agents, antibacterial agents, antifungal agents, herbicides, antioxidants, deodorants, nucleating agents, antiblocking agents, dropping agents, antifoggants, antimist agents, antistatic agents or these The degradable agricultural multi-film according to claim 1 or 2, which is formed by adding a mixture of the above. 6. An agricultural multi-film obtained by molding a resin composition containing a lactone resin, a synthetic aliphatic polyester resin and a fatty acid amide, wherein the constituent lactone resin of the agricultural multi-film is used alone or in another form. A degradable agricultural multi-film, which has been subjected to a radiation irradiation treatment together with at least one component. 7. The degradable agricultural multi-film according to claim 6, wherein the ratio of the fatty acid amide to the total of 100 parts by weight of the lactone resin and the synthetic aliphatic polyester resin is 0.2 to 5 parts by weight. 8. The lactone resin / synthetic aliphatic polyester resin weight ratio of 5/95 to 70/30.
8. The degradable agricultural multi-film according to any one of claims to 7. 9. A liquid lubricant is further added to the lactone resin and the synthetic aliphatic polyester resin in a total amount of 100 parts by weight.
The degradable agricultural multi-film according to any one of claims 6 to 8, comprising 1 to 3 parts by weight. 10. The degradable agricultural use according to any one of claims 6 to 9, further comprising 0.1 to 3 parts by weight of fine powder silica based on 100 parts by weight of the total of the lactone resin and the synthetic aliphatic polyester resin. Multi film. 11. A starch is further added to 10 parts by weight based on a total of 100 parts by weight of the lactone resin and the synthetic aliphatic polyester resin.
The degradable agricultural multi-film according to any one of claims 6 to 10, comprising 80 parts by weight. 12. The degradable agricultural multi-film according to claim 1, wherein the lactone resin is polyε-caprolactone. 13. The degradable agricultural multi-film according to claim 1, wherein an acrylic resin is coated on at least one side of the surface.