KR20170075052A - Resin composition for mulching film and biodegradable mulching film using the same - Google Patents

Abstract

(I) a biodegradable resin; (Ii) a starch in which at least one of the hydroxyl groups (-OH groups) in the glucose unit is hydrophobically treated with silane; And (iii) a graft copolymer obtained by grafting maleic anhydride (MA) to a biodegradable polymer, a polyfunctional compound having an epoxidized oil and an epoxy group, or a compatibilizer selected from the group consisting of And a biodegradable mulching film prepared from the resin composition. The resin composition for a mulching film according to the present invention can improve the workability and mulching function of a film by including a starch hydrophobized with silane. By including a compatibilizing agent, the binding force between the biodegradable resin and starch is improved, And the tensile strength and tensile elongation of the film can be improved.

Description

Technical Field [0001] The present invention relates to a resin composition for a mulching film, and a biodegradable mulching film using the resin composition,

The present invention relates to a resin composition for a mulching film and a biodegradable mulching film produced using the resin composition. More particularly, the present invention relates to a mulching film having improved mulching function by containing a starch and a compatibilizer, And a biodegradable mulching film prepared using the resin composition.

An agricultural mulching film is a film that covers the surface of a soil when cultivating crops and is generally made of a material such as polyethylene or polyvinyl chloride. These agricultural mulching films are used for controlling the weeding of crops, controlling the soil moisture or controlling the temperature, preventing the soil from being eroded by raindrops during rainfall, or optimizing the environment suitable for the growth of crops. It is used for the purpose.

Agricultural mulching films have contributed greatly to the agricultural productivity of Korea, but they have been recognized as a factor to pollute the environment of the rural area because of the difficulties in recycling after collection. Therefore, there has been an attempt to use biodegradable film for field farming or rice farming.

For example, Patent Document 1 (Korean Patent Registration No. 10-0545271) discloses a styrene-butadiene-styrene copolymer which is obtained by copolymerizing stearic acid, heavy calcium carbonate, a vinyl ketone copolymer polymer, a polyethylene wax, lactose, ethyl acetate, methyl methacrylate, (LDPE), Linear Low Density Polyethylene (LLDPE), High Density Polyethylene (HDPE), and the like are added to biodegradable compounds prepared by mixing low molecular weight polyethylene (LMPE) and low molecular polyethylene (LMPE) Discloses an agricultural mulching film formed by mixing and processing one or more selected plastic resins selected from the group consisting of polystyrene paper (PSP) and polypropylene (PP), followed by extrusion.

However, the mulching film is a synthetic polymer such as polypropylene, polyethylene, polystyrene or the like as a base polymer, and a biodegradable component is mixed as an additive. It is possible that biodegradation of the biodegradable component may be possible but biodegradation of the base polymer itself is impossible There was a limit to do. Therefore, when used in a soil, there is a fundamental problem that the base polymer is not decomposed in the future, thereby causing environmental pollution.

As a method for solving such a problem, Patent Document 2 (Korean Patent Laid-Open Publication No. 10-2014-0106882) discloses a biodegradable polyester resin composition containing polylactic acid, polybutylene adipate terephthalate and thermoplastic starch (TPS) A resin composition and an agricultural mulching film produced using the same. The mulching film is spontaneously decomposed at a high speed up to the base polymer by the microorganism of the soil or the like, and can be widely used environmentally friendly.

However, in the case of the mulching film produced from the biodegradable resin composition, the biodegradation rate is too fast, and the mechanical properties such as tensile strength and tensile elongation are rapidly lowered before reaching the harvest time of the crop after the coating. In this case, the mulching film can not withstand the force of stepping on the crop during the cultivation of the crop, and the mulching film is partially torn.

Therefore, there is a need for a research and development of a resin composition for a mulching film having an excellent mechanical property during a period required for harvesting crops after coating with a mulching film and having an appropriate biodegradation rate capable of being decomposed by microorganisms after the above period to be.

KR 100545271 B KR 1020140106882 A

The present invention aims to provide a resin composition for a mulching film which can improve the processability and mulching function of a film by including starch hydrophobized with silane together with a biodegradable resin.

The present invention provides a resin composition for a mulching film having improved binding force between a biodegradable resin and starch by including a compatibilizer.

The present invention also provides a biodegradable mulching film produced using the resin composition.

Disclosure of the Invention In order to solve the above problems, the present invention relates to a biodegradable resin composition comprising: (i) a biodegradable resin; (Ii) a starch in which at least one of the hydroxyl groups (-OH groups) in the glucose unit is hydrophobically treated with silane; And (iii) a graft copolymer obtained by grafting maleic anhydride (MA) to a biodegradable polymer, a polyfunctional compound having an epoxidized oil and an epoxy group, or a compatibilizer selected from the group consisting of To provide a resin composition for a mulching film.

The biodegradable resin may be selected from the group consisting of polybutylene adipate-co-terephthalate (PBAT), poly (butylene succinate), PBS, polybutylene succinate adipate may include (butylene succinate-co-adipate) , PBSA), polylactic acid (Polylastic acid, PLA) and polyhydroxyalkanoates (polyhydroxyalkanoate, PHA) over either or both selected from the group consisting of.

The biodegradable resin and the starch are preferably contained in a weight ratio of 65:35 to 90:10.

The graft copolymer may be polybutylene adipate-co-terephthalate (PBAT-MA), and the epoxidized oil may be epoxidized Epoxidized soybean oil (ESO), and the polyfunctional compound may be a bifunctional polyepoxide.

The content of the compatibilizing agent is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch.

The compatibilizing agent may include the graft copolymer and the epoxidized oil, wherein the graft copolymer and the epoxidized oil are preferably contained in a weight ratio of 1: 5 to 5: 1.

The resin composition for a mulching film according to the present invention may further contain a plasticizer in an amount of 5 to 20 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch, and the plasticizer may be glycerol, sorbitol, 1,4-butanediol, Glycol, propylene glycol, polyethylene glycol, and polypropylene glycol.

The resin composition for a mulching film may be any one selected from the group consisting of titanium dioxide (TiO ₂ ), calcium carbonate (CaCO 3), talc, carbon black, barium sulfate (BaSO ₄ ) and wollastonite (CaSiO ₃ ) More than two pigments may be added in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch.

The present invention also provides a biodegradable mulching film prepared using the resin composition for a mulching film.

INDUSTRIAL APPLICABILITY The resin composition for a mulching film according to the present invention can improve the processability of a film by using a starch in which at least one hydroxyl group (-OH group) of a glucose unit has been subjected to hydrophobization treatment with silane, and also has a biodegradation rate It is possible to prevent the degradation of the physical properties of the film before harvesting the crop, and thus the mulching function of the film can be improved.

The resin composition for a mulching film according to the present invention can improve the dispersibility of the starch by improving the binding force between the biodegradable resin and the starch by including a compatibilizer and can improve the tensile strength and tensile elongation after the production of the film .

In addition, the mulching film produced by using the resin composition for a mulching film according to the present invention does not cause environmental problems because it is biodegraded after a certain period of time after harvesting of the crop.

Fig. 1 shows the results of cultivation of the crops at 0, 30 and 72 days after the mulching film produced in Example 3 and Comparative Example 2 (immediately after crop harvesting) and 72 days (after harvesting the crops after rotary harvesting) It is the photograph which compares the scene.

(I) a biodegradable resin; (Ii) a starch in which at least one of the hydroxyl groups (-OH groups) in the glucose unit is hydrophobically treated with silane; And (iii) a graft copolymer obtained by grafting maleic anhydride (MA) to a biodegradable polymer, a polyfunctional compound having an epoxidized oil and an epoxy group, or a compatibilizer selected from the group consisting of And a biodegradable mulching film prepared from the resin composition.

Hereinafter, the resin composition for a mulching film according to the present invention will be described separately for each constituent component.

(I) biodegradable resin

In the resin composition for a mulching film of the present invention, the biodegradable resin is a component that imparts a predetermined level of tensile strength and tensile elongation to the mulching film while simultaneously imparting biodegradability. The biodegradable resin may be an aliphatic polyester-based biodegradable resin or an aliphatic / Ester-based biodegradable resins, and the like, as long as they are conventionally used. For example, the biodegradable resin may be selected from the group consisting of poly (butylene adipate-co-terephthalate), PBAT, poly (butylene succinate), and polybutylene succinate adipate may include (poly (butylene succinate-co- adipate), PBSA), polylactic acid (Polylastic acid, PLA) and polyhydroxyalkanoates (polyhydroxyalkanoate, PHA) over either or both selected from the group consisting of, Considering the physical properties and the like of the mulching film, PBAT can be preferably included.

(Ii) starch

In the resin composition for a mulching film of the present invention, starch accelerates biodegradability of a mulching film. In the present invention, a starch in which at least one hydroxyl group (-OH group) of a glucose unit has been hydrophobically treated with a silane is used.

The hydrophobic process by silane treatment of the starch in which at least one of the hydroxyl groups (-OH groups) of the glucose unit has been hydrophobically treated with silane, such as 3-chloropropyl trimethoxysilane (CPMS) The used hydrophobic process is shown in the following chemical reaction formula 1.

Chemical equation 1

The starch to which at least one hydroxyl group (-OH group) of the glucose unit has been hydrophobically treated with silane by the above-described chemical reaction process can be prepared and used by a known technique, but a commercially available product can also be used. "Beneform (R)" of the draw Meridian Korea ㈜ making a concrete example of the commercial product series, e.g. Beneform ^TM 1100, Beneform ^TM 1000, Beneform ^TM 2000, Beneform ^TM 4000 may be used alone or in combination, more preferably Beneform ( ^TM) 1100 may be used.

The starch hydrolyzed with silane as described in the present invention is not only excellent in workability but also can be degraded after coating in comparison with a conventional mulching film using thermoplastic starch (TPS). Therefore, the problem caused by the conventional biodegradable mulching film, that is, the speed at which the mulching film is biodegraded after being coated on the surface of the soil is too fast, the mechanical properties of the film are rapidly deteriorated, The problem of tearing the film can be solved.

In the present invention, the biodegradable resin and the starch are preferably contained in a weight ratio of 65:35 to 90:10. If the ratio of the starch to the biodegradable resin exceeds the upper limit of the above range, the kneading property may be deteriorated and a problem may arise in forming the film. Even after molding, the film may not maintain its function for a desired period due to rapid decomposition after film- Therefore, it is not preferable. On the other hand, when the ratio of the starch to the biodegradable resin is less than the lower limit of the range, that is, when the ratio of the biodegradable resin is relatively excessively large, the decomposition rate is slow, which is not preferable because there is a problem in rotary operation after crop harvest.

(Iii)

In the resin composition for a mulching film of the present invention, the compatibilizer improves the dispersibility of the starch and improves the tensile and tear strength after producing the film as a component for improving the binding force between the biodegradable resin and the starch.

The compatibilizing agent may include any one or more selected from the group consisting of a graft copolymer obtained by grafting maleic anhydride (MA) to a biodegradable polymer, a polyfunctional compound having an epoxidized oil and an epoxy group have.

Specifically, the graft copolymer may be a graft copolymer in which maleic anhydride (MA) is grafted onto any one or two or more biodegradable polymers selected from the group consisting of PBAT, PBSA and PBS, preferably polybutyl It may be poly (butylene adipate-co-terephthalate) -Maleic anhydride (PBAT-MA). The graft copolymer may be prepared by a known technique. For example, maleic anhydride (MA) may be added to the biodegradable resin, and then an initiator such as dicumyl peroxide may be added to the biodegradable resin to prepare a twin- screw extruder.

The reaction mechanism when the graft copolymer improves the binding force between the biodegradable resin and the starch in the resin composition for a mulching film according to the present invention, for example, when PBAT-MA is used, is shown in the following chemical reaction formula 2.

Chemical equation 2

As shown in the above chemical formula 2, the COC ring of the maleic anhydride moiety in PBAT-MA is broken and forms a chemical bond with one -OH group of the starch, and the other -OH group of the starch is also bound to the open maleic anhydride residue Lt; RTI ID = 0.0 > carboxyl group < / RTI > Then, the PBAT-MA combined with the starch binds with the biodegradable resin in the resin composition for mulching film to form a matrix polymer, and the binding of the starch and the biodegradable resin can be improved while the reaction is diffused. In addition, since the starch is present in a state bound to a biodegradable polymer such as PBAT, it exhibits excellent dispersibility without being easily separated even during the extrusion process for preparing a master batch of pellets or producing a mulching film. Therefore, in the case of a mulching film produced using a biodegradable resin composition containing a compatibilizing agent, mechanical properties such as tensile strength and tear strength can be improved.

The reaction mechanism of the graft copolymer in the resin composition for a mulching film as described in the above chemical reaction formula 2 can be applied similarly to the case of a polyfunctional compound having an epoxidized oil and an epoxy group as other compatibilizers used in the present invention have. However, in the case of the polyfunctional compound having an epoxidized oil and an epoxy group, the epoxy ring is opened instead of ring opening of the maleic anhydride ring, thereby improving the binding force between the biodegradable resin and the starch.

 The epoxidized oil can be an epoxidized vegetable oil, which is an epoxy group introduced into the vegetable oil. Examples of the vegetable oil include soybean oil, linseed oil, sunflower seed oil, safflower oil, hempseed oil, oiticica oil, Sesame oil, cottonseed oil, castor oil, olive oil, peanut oil, rapeseed oil, coconut oil, babassu oil, oil, palm oil, etc. may be used. As the epoxidized oil, epoxidized soybean oil (ESO) represented by the following general formula (1) may be used.

Formula 1

The polyfunctional compound having an epoxy group may be a bifunctional polyepoxide, for example, an epoxy group-containing styrene / acrylic acid ester copolymer. The epoxy equivalent of the polyfunctional compound is preferably 150 to 3,000 g / mol, more preferably 200 to 600 g / mol, in consideration of reactivity and moldability. Here, the epoxy equivalent means the number of grams of the polymer containing one equivalent of an epoxy group. The weight average molecular weight (Mw) of the compound is preferably from 2,000 to 25,000, and more preferably from 3,000 to 8,000, in view of the reactivity and compatibility with the resin. The weight average molecular weight (Mw) referred to herein is a weight average molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

The polyfunctional compound can be prepared and used by a known technique, but a commercially available product can also be used. Specific examples of commercially available products include "JONCRYL (registered trademark)" series sold by BASF ^. ADR-4368 can be preferably used. The Joncryl ^? ADR-4368 is a bifunctional polyepoxide represented by the following formula (2) and has a styrene unit, a (meth) acrylate unit and a glycidyl (meth) acrylate unit. In the following formula (2), the respective constituent units are shown successively, but the respective constituent units may be bonded in any order and may be a block copolymer or a random copolymer.

(2)

In Formula 2, R ₁ to R ₅ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R ₆ represents an alkyl group having 1 to 12 carbon atoms. And x and z are each independently an integer of 1 to 35 and y is an integer of 1 to 20.

The content of the compatibilizer used in the present invention is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch. When the content is less than 1 part by weight, the compatibility between the biodegradable resin and the starch can not be sufficiently secured, and thus the film processability and physical property improvement effect may be insufficient. On the other hand, when the content exceeds 10 parts by weight, the molecular weight and reactivity are too high, The melt index (MI) is lowered, and gelation may occur during processing of the film or poor processability may occur.

Also preferably, the compatibilizer may comprise the graft copolymer and the epoxidized oil, wherein the graft copolymer and the epoxidized oil may be included in a weight ratio of 1: 5 to 5: 1, In this case, it is preferable in terms of compatibility between the biodegradable resin and the starch and mechanical stiffness of the film.

(Iv) a plasticizer

The resin composition for a mulching film according to the present invention may further comprise a plasticizer. The plasticizer penetrates between the starch and the starch to weaken the hydrogen bonds between the starch molecules and loses crystallinity of the starch, thereby converting the starch into an amorphous form. When the composition for a mulching film is molded into a pellet or a composition for a mulching film And serves to improve moldability and workability in molding with a film.

The content of the plasticizer is preferably 5 to 20 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch. If the content of the plasticizer is less than 5 parts by weight, the plasticizing effect of the starch may be deteriorated. On the other hand, if it exceeds 20 parts by weight, the mechanical properties of the film may be deteriorated.

Examples of the plasticizer include those used in polymer molding such as glycerol, sorbitol, 1,4-butanediol, ethylene glycol, maltose, sucrose, cyclodextrin, propylene glycol, urea, polyethylene glycol, and polypropylene glycol. . However, considering compatibility with starch and the like, the plasticizer is preferably one selected from the group consisting of glycerol, sorbitol, 1,4-butanediol, ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol May include two or more, and more preferably, may contain glycerol.

In addition, the mulching film resin composition according to the present invention may further include a pigment to secure the hiding power of the mulching film, and the content of the pigment is preferably 0.5 to 10 wt% based on 100 parts by weight of the total amount of the biodegradable resin and the starch Can be. As the pigment, any one or two or more selected from the group consisting of titanium dioxide (TiO ₂ ), calcium carbonate (CaCO 3), talc, carbon black, barium sulfate (BaSO ₄ ) and wollastonite (CaSiO ₃ ) have.

Meanwhile, the shape of the resin composition for a mulching film according to the present invention is not limited as long as the components are uniformly mixed, but considering that the resin composition is used as a master batch in the production of a biodegradable mulching film , It is preferable that it is in a pellet form. The composition for a mulching film in the form of a pellet can be prepared by mixing and melting the constituents thereof and then pelletizing the extrudate while extruding.

The master batch can be prepared by blending the biodegradable resin, starch, compatibilizer, plasticizer or pigment, which are the constituents of the resin composition for a mulching film of the present invention, according to each content. In this case, Cast mulching film can be produced. Alternatively, a biodegradable resin may be added to the master batch after preparing a master batch by mixing the starch, a compatibilizing agent, a plasticizer, or a pigment according to each content, A mulching film may be produced.

The present invention also provides a biodegradable mulching film prepared using the resin composition for a mulching film.

A preferred method of forming the biodegradable mulching film according to the present invention is extrusion molding, and a composition for a mulching film can be formed into a film form using a conventional extruder such as a plate-like extrusion nozzle. Since the biodegradable mulching film of the present invention contains starch and at least one compatibilizer that has been hydrophobically treated with silane in at least one hydroxyl group (-OH group) of the glucose unit, when compared with a conventional biodegradable mulching film containing thermoplastic starch , Exhibits excellent mechanical strength during the period required for growing the crop after the coating, and decomposes to the same extent as the conventional biodegradable resin after a certain period of harvesting of the crop, thereby causing no environmental problems.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these embodiments.

Example 1

22.5 parts by weight of PBAT, 12 parts by weight of starch Beneform ^TM manufactured by Ingridian Korea 27.5 parts by weight of 1100, 5 parts by weight of compatibilizer and 10 parts by weight of glycerol were mixed and then pelletized while extruding to prepare a master batch (M / B) for a mulching film. The extruder used was a twin extruder having a screw diameter of 44 mm, an extrusion speed of 300 rpm, a feed rate of 40 rpm, and a barrel temperature of 180 캜.

5 parts by weight of PBAT and 1.25 parts by weight of carbon black were mixed and a black master batch (M / B) was prepared in the same manner as the M / B for the mulching film.

65 parts by weight of M / B for the mulching film, 6.25 parts by weight of the black M / B and 45 parts by weight of PBAT as a biodegradable resin were dry-blended to prepare a resin composition for a mulching film, , And a film was produced with a film molding machine (Daerun Machinery Co., Ltd., model: 50 mm HD / PE FILM M / C). The barrel temperature was set at 160 占 폚 and the die temperature was set at 180 占 폚. An agricultural mulching film having a thickness of 0.02 mm was produced at an extrusion speed of 500 rpm, a feed rate of 100 rpm, and a roll speed of 200 rpm.

Examples 2 to 4 and Comparative Example 1

An agricultural mulching film was prepared in the same manner as in Example 1, except that the composition of the resin composition for a mulching film was adjusted as shown in Table 1 below. In the following Table 1, the unit of each composition is parts by weight.

Comparative Example 2

65 parts by weight of PBAT and 30 parts by weight of thermoplastic starch (TPS, KYOTO) were mixed and then pelletized while being extruded to prepare M / B for a mulching film. The extruder used was a twin extruder having a screw diameter of 44 mm, an extrusion speed of 300 rpm, a feed rate of 40 rpm, and a barrel temperature of 180 캜.

5 parts by weight of PBAT and 1.25 parts by weight of carbon black were mixed and black M / B was prepared in the same manner as M / B for the mulching film.

95 weight parts of M / B for the mulching film and 6.25 weight parts of black M / B were dry-blended to prepare a resin composition for a mulching film. Using the resin composition, a film molding machine (Daerun Machinery Co., 50 mm HD / PE FILM M / C). The barrel temperature was set at 160 占 폚 and the die temperature was set at 180 占 폚. An agricultural mulching film having a thickness of 0.02 mm was produced at an extrusion speed of 500 rpm, a feed rate of 100 rpm, and a roll speed of 200 rpm.

Comparative Example 3

An agricultural mulching film was prepared in the same manner as in Comparative Example 2, except that the composition of the resin composition for a mulching film was adjusted as shown in Table 1 below. In the following Table 1, the unit of each composition is parts by weight.

M / B for mulching film Black M / B When manufacturing film PBAT ^* Starch Commercialization a Commercialization b Commercialization c Gly
Serol PBAT ^** PBAT ^*** Example 1 22.5 27.5 5 - - 10 5 45 Example 2 22.5 27.5 - One 10 5 45 Example 3 22.5 27.5 5 One - 10 5 45 Example 4 22.5 27.5 - - One 10 5 45 Comparative Example 1 22.5 27.5 - - - 10 5 45 Comparative Example 2 65 30 ^**** - - - - 5 - Comparative Example 3 65 30 ^**** 5 - - - 5 -

1) the PBAT ^* is a biodegradable resin to be mixed when M / B for manufacturing mulching films, the PBAT ^** is a biodegradable resin to be mixed during manufacture Black M / B, PBAT ^*** said masterbatch manufacturing mulching films And a dry biodegradable resin.

2) 30 ^**** indicates that 30 parts by weight of TPS was used, and Beneform ^TM 1100 was used as starch in Examples 1 to 4 and Comparative Example 1.

3) The compatibilizer a was prepared by adding 1.5 parts by weight of maleic anhydride to 100 parts by weight of PBAT and then adding 0.15 part by weight of dicumyl peroxide as an initiator, using a twin extruder under the same conditions as in the master batch extrusion described in Example 1 PBAT-MA.

4) The compatibilizing agent b was an epoxidized soybean oil, and a product for Sigma-Aldrich reagent was used.

5) The compatibilizing agent c is a bifunctional polyepoxide prepared by the method described in BASF's trade name Joncryl ^? ADR-4368 (Mw (in terms of PMMA) 6,800, epoxy equivalent 285 g / mol) was used.

<Evaluation method>

1. Measurement of mechanical properties

The tensile strength and tensile elongation in the longitudinal direction (MD) and the transverse direction (TD) of the mulching films prepared according to Examples 1 to 4 and Comparative Examples 1 and 2 were measured in accordance with JIS K6251-1, The results are shown in Table 2 below.

Tensile strength MD
(kgf / cm ² ) Tensile strength TD
(kgf / cm ² ) Tensile elongation MD
(%) Tensile elongation TD
(%) Example 1 188.3 162.3 423.9 464.6 Example 2 186.3 160.4 463.7 491.5 Example 3 227.4 207.7 435.5 470.0 Example 4 193.3 175.5 433.6 466.7 Comparative Example 1 177.2 150.8 417.4 454.9 Comparative Example 2 213.1 180.1 453.3 340.2 Comparative Example 3 220.3 185.1 443.5 335.6

As shown in Table 1, the mulching films prepared according to Examples 1 to 4 exhibited excellent machine direction (MD) and tensile strength and tensile elongation at transverse direction (TD) .

Specifically, in the case of the mulching films prepared according to Examples 1 to 4, the tensile strength and the tensile elongation were superior to those of the mulching film of Comparative Example 1 which did not include a compatibilizing agent, and even when including the compatibilizing agent, It can be confirmed that the lateral tensile elongation (tensile elongation TD) is significantly improved as compared with Comparative Example 3 using TPS. In the case of Comparative Example 2 in which TPS was used as the starch without the compatibilizing agent, the transverse tensile elongation was significantly lowered in comparison with the mulching films of Examples 1 to 4.

On the other hand, in the case of the mulching film of Example 3, the tensile elongation MD shows a similar level to that of Comparative Examples 2 and 3, but the tensile strength MD, the tensile strength TD and the tensile elongation TD are superior to those of Comparative Examples 1 to 3 As a result, it can be seen that when the graft copolymer and the epoxidized oil are used together as the compatibilizing agent, more preferable effect is exhibited.

2. Evaluation of biodegradability

The mulching films prepared according to Example 3 and Comparative Example 2 were coated on the soil of Jusan soil in the horseshoe surface of Wonju city, Gangwon-do, and after the lapse of 30 days from the coating, 72 days after coating (immediately after harvesting the crop) Biodegradability was assessed by visually confirming the progress of degradation of the coated mulching film after the work (taken after the rotary work on the harvested plantation area). At this time, Chinese cabbage was used as the evaluation crop.

Fig. 1 shows the results of cultivation of the crops at 0, 30 and 72 days after the mulching film produced in Example 3 and Comparative Example 2 (immediately after crop harvesting) and 72 days (after harvesting the crops after rotary harvesting) It is the photograph which compares the scene.

1, the mulching film according to the comparative example 2 already found a torn part, whereas the mulching film produced according to the example 3 has a torn part It can be confirmed that the mulching function is improved.

In addition, when the cultivation area was visually inspected immediately after harvesting of the crops (72 days after coating), the tearing degree of the mulching film produced according to Comparative Example 2 was observed to be higher than that of Comparative Example 2, but on the same day As a result of observing the harvested field after rotary working, all of the mulching films produced according to Example 3 and Comparative Example 2 were torn finely to the same extent, so that the shape of the film remained after mixing with the soil. The fact that both films are torn to the same pressure at the same level indicates that the biodegradation rate of both films becomes similar after 72 days of coating and that their mechanical properties fall to similar levels.

As a result, the mulching film produced according to Example 3 had excellent mulching function due to mechanical properties resisting external pressure at 30 days after coating in cultivation of the crop, and after 72 days (harvest date) after coating, It can be understood that the film has excellent biodegradability which is decomposed by external pressure due to its physical properties.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiment, but is to be accorded the widest scope consistent with the appended claims and their equivalents. Should be construed as being included in the scope of the present invention.

Claims (11)

(I) biodegradable resin;
(Ii) a starch in which at least one of the hydroxyl groups (-OH groups) in the glucose unit is hydrophobically treated with silane; And
(Iii) a graft copolymer obtained by grafting maleic anhydride (MA) to a biodegradable polymer, a polyfunctional compound having an epoxidized oil and an epoxy group, and Resin composition for mulching film. The method according to claim 1,
The biodegradable resin may be selected from the group consisting of polybutylene adipate-co-terephthalate (PBAT), poly (butylene succinate), PBS, polybutylene succinate adipate (butylene succinate-co-adipate) , PBSA), polylactic acid (Polylastic acid, PLA) and polyhydroxyalkanoates (mulching comprising the polyhydroxyalkanoate, PHA) over either or both selected from the group consisting of Resin composition for film. The method according to claim 1,
Wherein the biodegradable resin and the starch are contained in a weight ratio of 65:35 to 90:10. The method according to claim 1,
Wherein the graft copolymer is polybutylene adipate terephthalate-maleic anhydride (PBAT-MA). 2. The resin composition for a mulching film according to claim 1, wherein the graft copolymer is polybutylene adipate-co-terephthalate. The method according to claim 1,
Wherein the epoxidized oil is an epoxidized soybean oil (ESO). The method according to claim 1,
Wherein the polyfunctional compound is a bifunctional polyepoxide. The method according to claim 1,
Wherein the content of the compatibilizing agent is 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch. The method according to claim 1,
Wherein the compatibilizer comprises the graft copolymer and the epoxidized oil in a weight ratio of 1: 5 to 5: 1. The method according to claim 1,
Wherein the resin composition contains one or more plasticizers selected from the group consisting of glycerol, sorbitol, 1,4-butanediol, ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol in a total amount of 100 parts by weight of the biodegradable resin and starch By weight based on the total weight of the resin composition. The method according to claim 1,
The resin composition may further comprise one or more pigments selected from the group consisting of titanium dioxide (TiO ₂ ), calcium carbonate (CaCO 3), talc, carbon black, barium sulfate (BaSO ₄ ) and wollastonite (CaSiO ₃ ) Wherein the resin composition further comprises 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the biodegradable resin and the starch. A biodegradable mulching film produced by using the resin composition for a mulching film according to any one of claims 1 to 10.

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