KR102334430B1 - Biodegradable mulching film having the improved anti-hydrolysis property and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a biodegradable mulching film having excellent water resistance and a method for manufacturing the same. The manufacturing method of a biodegradable mulching film with excellent water resistance selects heterogeneous biodegradable resins with different biodegradation rates so that the biodegradation period can be delayed during mulching. At least one additive selected from the group consisting of antioxidants, UV absorbers, and light stabilizers, consisting of a primary antioxidant and a secondary antioxidant including It provides a biodegradable mulching film with excellent water resistance through an annealing process that increases the

Description

Biodegradable mulching film with excellent water resistance and manufacturing method thereof

The present invention relates to a biodegradable mulching film having excellent water resistance and a method for producing the same, and more particularly, to select a different biodegradable resin having a different biodegradation rate so that the biodegradation period can be delayed during mulching, and a chain extender to the biodegradable resin , a hydrolysis resistance agent, one or more additives selected from the group consisting of a primary antioxidant including a phenolic antioxidant and a secondary antioxidant including a phosphorus antioxidant, a UV absorber, and a light stabilizer It relates to a biodegradable mulching film having excellent water resistance through an annealing process to remove residual stress at a constant high temperature and a method for manufacturing the same.

Mulching refers to work carried out for the purpose of preventing soil erosion, maintaining soil moisture, controlling the temperature, controlling weeds, preventing infectious diseases in the soil, and preventing soil contamination by covering the land where crops are grown with plastic or straw. .

Since the development of agricultural mulching film, it has been used in plastic houses, vinyl tunnels, plastic caps, and suppression of weed growth from primitive agricultural cultivation methods, thereby solving the high income and manpower shortage for producers, and consumers can enjoy fresh products anytime, anywhere. It can be said that it was an opportunity for a major agricultural revolution by being able to supply fruits and vegetables at a low price, but agricultural films are widely distributed to each farmer year after year, and the usage is rapidly increasing.

Incineration of waste vinyl generated during the farming process and landfilling in soil causes contamination of farmland and damage to rural landscape. They are left unattended in the soil or buried, which can hinder crop growth, cause pollution, and are not aesthetically pleasing.

In addition, even the collected waste vinyl can be recycled through various processes such as cleaning and drying foreign substances, but the cost of recycling is more expensive than recycled products, so it is passive in reprocessing, and agricultural mulching film is collected and incinerated after use Or, by being treated by a landfill method, dust and toxic gas are emitted, causing various secondary pollution, and the severity is increasing day by day.

The development and dissemination of eco-friendly agricultural mulching film is made by mixing the existing non-biodegradable plastic film (vinyl-based) with a polymer with excellent biodegradability, appropriate additives, and antioxidants. It is efficient and has advantages such as weed suppression, pest prevention effect, and geothermal preservation, and has the advantage of biodegradation when discarded.

Although the goal of the mulching film development market is to develop an eco-friendly agricultural film that is environmentally friendly and has excellent biodegradability, the agricultural mulching film currently used is made of polyethylene (PE) based on low-density polyethylene (LDPE), a petrochemical product. Most of the films are used, and the difficult-to-decompose mulching film that is not collected remains in the soil, causing long-term soil contamination and deterioration of soil strength, and in the longer term, it is the cause of a decrease in production.

In addition, efforts to find eco-friendly plastic materials as described above have been steadily progressing amid concerns about depletion of oil reserves, environmental pollution, prevention of global warming, and rising oil prices.

As a representative biodegradable plastic material, polylactic acid (PLA: Poly Lactic Acid) is usually produced by separating starch from corn and condensing lactic acid fermented with glucose to form a polymer. As a material that is completely biodegradable into water (H ₂ O) and carbon dioxide (CO ₂ ), it has been approved as a biodegradable raw material harmless to the human body and the environment by the U.S. Food and Drug Administration (FDA), Korea Food and Drug Administration, and European related organizations such as Canada, Japan and Germany. am.

Nevertheless, when a thin film-type substrate is made with polylactic acid (PLA) alone, the original physical properties of the material are limited, and the properties of tensile strength, tear and elongation are insufficient. .

Patent Document 1 is a biodegradable agricultural mulching film extruded by mixing a biodegradable compound with a base polymer of synthetic resins such as polyethylene or polystyrene. It is reported that it can suppress the growth of weeds and prevent pests and pests, thereby significantly reducing the use of pesticides, and preventing environmental pollution as it is decomposed by microorganisms in the natural state after a certain period of time has elapsed.

However, in the present invention, the plastic resin mixed with the biodegradable compound is LDPE, LLDPE (Linear LDPE), HDPE (High Density Polyethylene), polystyrene paper (PSP: Polystyrene Paper) and polypropylene (PP: Polypropylene) any one or A mixture of these is used, and as a more preferred embodiment, a mulching film extruded by mixing 12% by weight of LDPE and 48% by weight of LLDPE as a plastic resin to 40% by weight of a biodegradable compound is provided.

Patent Document 2 provides a biodegradable agricultural mulching film using polylactic acid, but polylactic acid, heavy calcium carbonate, aliphatic polyester, lactose, ethyl acetate, methyl methacrylate, powdered milk, biodegradation aid, and a biodegradable agent are mixed. It is a film extruded by mixing a sexual compound with a base polymer of synthetic resins such as polyethylene or polystyrene, and is mixed with a base polymer of non-degradable synthetic resins such as polyethylene or polystyrene.

Therefore, such a film can be called a biodegradable mulching film, not a degradable mulching film, and when continuously used, its residues remain in the soil, which can cause secondary pollution of farmland and a decrease in agricultural production due to deterioration of fertility. have.

Patent Document 3 relates to a biodegradable double film using a biodegradable WPC (Wood Polymer Composition), wherein the biodegradable resin is polylactic acid (PLA) 50-75 wt%, and AP (Aliphatic Polyester)-based biodegradable resin 20- It is a mixture of 35% by weight and 5 to 15% by weight of a polyurethane (PU: Polyurethane)-based biodegradable resin. Because it uses a non-degradable polyurethane (PU) resin, it does not completely biodegrade, so residues contaminate the soil. can provide a cause.

Recently, in the field of mulching films using biodegradable materials, it is difficult to adjust the decomposition time depending on the temperature and humidity of the soil, the type of crop, and the fertility of the soil. As another problem is pointed out, technology development is required to increase the water resistance of the biodegradable mulching film.

Korean Patent No.0545271 (published on Jan. 24, 2006) Korean Patent No. 0903886 (published on June 24, 2009) Korean Patent No. 1176604 (published on August 23, 2012)

Accordingly, the present inventors use only internationally certified biodegradable resins without using any non-degradable resins in accordance with the demand for increased water resistance required for conventional biodegradable mulching films, but select heterogeneous biodegradable resins with different biodegradation rates during mulching The biodegradation period can be controlled, and various functional additives such as primary and secondary antioxidants, heat stabilizers, chain extenders, hydrolysis resistance agents, slip agents, dispersants, etc. are used in the raw material selection and extrusion process. to prevent moisture content and increase the durability of the biodegradable mulching film, so that it can play a role in mulching during the desired crop growth period. The invention was completed.

It is an object of the present invention to provide a biodegradable mulching film having excellent water resistance.

Another object of the present invention is to provide a method for manufacturing a biodegradable mulching film optimizing durability and water resistance by processing through an annealing process of pellets after compounding and extruding by selecting and mixing an optimal raw material.

In order to achieve the above object, (i) a biodegradable resin composition (ii) a slip agent, an antioxidant comprising a primary antioxidant including a phenolic antioxidant and a secondary antioxidant including a phosphorus antioxidant, ultraviolet (UV) ) At least one additive selected from the group consisting of an absorbent and a light stabilizer is blended to melt-extrude a biodegradable mulching film resin with excellent water resistance that satisfies an acid value of 0.5 to 2.0, and (iii) melt-extrusion through a high-temperature annealing process of the extruded resin By relieving the residual stress inside the resin formed in the process, the expression of physical properties is maximized and the degree of crystallinity is increased, so that various microorganisms (bacteria, mold, fungus, etc.) and enzymes in the soil can fully access the active site (active site). site) to prevent hydrolyable linkage at an early stage, providing a film with improved water resistance compared to the existing biodegradable mulching film.

The biodegradable resin composition is polybutylene adipate terephthalate (poly(butylene adipate-co-terephthalate), PBAT), polybutylene succinate (poly(butylene succinate), PBS) and polylactic acid (PLA) Any one or two or more selected from the group consisting of is used. More preferably, the first component of polylactic acid (PLA) and the second component of the aliphatic-aromatic polyester resin, polybutylene adipate-co-terephthalate (PBAT), are biodegradable resins. is to use

The antioxidant comprising the primary antioxidant and the secondary antioxidant is preferably blended in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the biodegradable resin.

In addition, in the above, the UV absorber and the light stabilizer are each blended in 0.1 to 0.9 parts by weight based on 100 parts by weight of the biodegradable resin.

The present invention provides a method for producing the biodegradable mulching film excellent in water resistance. More specifically, (1) a biodegradable resin and a slip agent, an antioxidant comprising a primary antioxidant including a phenolic antioxidant, and a secondary antioxidant including a phosphorus antioxidant, a UV absorber, and a light stabilizer Blending one or more additives selected from, (2) melt-extruding to form resin pellets, (3) high-temperature annealing of the extruded resin pellets, and (4) extruding the film after the annealing.

In the above, the annealing step stirs the extruded resin pellets at a high temperature of 90 to 120° C. and minimizes the amorphous region having a loose structure with irregular and low orientation between molecular chains to increase the degree of crystallinity and melt It is carried out in a process that can effectively remove residual stress caused by frictional heat and pressure between extrusions and irregular cooling rates between the inside and outside of the resin, thereby improving the bonding force between the resins and maximizing the expression of physical properties.

According to the present invention, the biodegradable resin and the biodegradable resin composition include a slip agent, a primary antioxidant including a phenolic antioxidant, and a secondary antioxidant including a phosphorus antioxidant, a UV absorber and a light stabilizer. It is possible to provide a mulching film with excellent water resistance by blending one or more additives selected from the group consisting of, and maximizing the physical properties of the biodegradable resin composition through annealing the compounded pellets at a constant high temperature.

In addition, through the high-temperature annealing process of the extruded resin, the residual stress inside the resin formed in the melt extrusion process is resolved to maximize the expression of physical properties and increase the crystallinity, so that various microorganisms in the soil (such as bacteria, fungi, fungi, etc.) and enzymes It is possible to provide a film with improved water resistance compared to the existing biodegradable mulching film by minimizing the active site to which the Through this process, the moisture content is reduced, so it is possible to secure competitiveness to shorten the dehumidification drying time by 70% or more.

When the biodegradable mulching film of the present invention is buried in soil and the polymer is reduced to a low molecular weight by water, microorganisms and enzymes, and is decomposed to a size that microorganisms can completely digest, it is completely biodegraded by the metabolic action of microorganisms to activate soil microorganisms, It is possible to provide an eco-friendly biodegradable mulching film that is not harmful to the soil ecosystem.

Therefore, the mulching film of the present invention is completely biodegradable, so it is not necessary to collect the crops after harvest, saving labor, and greatly reducing the social cost required for the collection and treatment of agricultural waste vinyl, and even without illegal incineration And, even when incinerated, the generation of environmental hormones and harmful gases is less than that of conventional polyethylene (PE), and the effect of reducing the generation of carbon dioxide, which is one of the causes of global warming, by 30% or more can be expected.

1 is a test result for weed growth during the biodegradation period after mulching the biodegradable mulching film prepared by the manufacturing method according to Example 1 of the present invention;
2 is a test result for weed growth during the biodegradation period after mulching the biodegradable mulching film prepared according to Comparative Example 1;
Figure 3 shows the temperature change of 10 cm in the soil under the mulching film after mulching,
Figure 4 shows the change in humidity of 10 cm in the soil under the mulching film after mulching,
Figure 5 shows the change in weight of the film (width 50cm, length 1m) with the lapse of the period after mulching,
6 shows the biodegradation test report of the Chemical Convergence Testing Institute.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The present invention relates to an antioxidant comprising (i) a biodegradable resin composition and (ii) a slip agent, a primary antioxidant including a phenolic antioxidant, and a secondary antioxidant including a phosphorus antioxidant, a UV absorber, and a light stabilizer. It provides a biodegradable mulching film with excellent water resistance that satisfies an acid value of 0.5 to 2.0 by blending one or more additives selected from the group consisting of By increasing the degree of crystallinity and minimizing the active site where various microorganisms (bacteria, fungi, fungi, etc.) and enzymes in the soil can have sufficient accessibility, enzyme cleavage occurs in the polymer main chain and hydrolysis By preventing hydrolyable linkage at an early stage, it is possible to provide a film with improved water resistance compared to the existing biodegradable mulching film.

(i) biodegradable resin used in the present invention is polybutylene adipate-co-terephthalate (PBAT), polybutylene succinate (poly(butylene succinate), PBS) and polylactic acid (polylactic acid, PLA) alone or two or more selected from the group consisting of may be used.

More preferably, polylactic acid (PLA) is included as a first component, and an optimum aliphatic-aromatic polyester resin having a low acid value and a low melt flow index (MI) is contained as a second component. do. As an example of the aliphatic-aromatic polyester resin, polybutylene adipate terephthalate (PBAT) is preferable.

The aliphatic-aromatic polyester resin is dimethyl terephthalate in which one benzene ring is introduced between diol and carboxylic acid groups in which 1 to 6 _{-CH 2 - is introduced between alcohol groups, or -CH between terephthalate and carboxylic acid groups.} and aliphatic-aromatic polyesters which are polycondensed with diacids having 1 to 6 _{2-valents introduced therein, and copolymers thereof.}

The biodegradable resin of the present invention is most preferably made of PLA (polylactic acid) and PBAT (polybutylene adipate terephthalate).

The polybutylene adipate terephthalate (PBAT) is superior to polylactic acid (PLA) in melt processability and flexibility and somewhat inferior in mechanical strength. Although it has biodegradability that is decomposed into carbon dioxide and water by such as, other aliphatic polyesters such as PBS (Polybutylene Succinate), PHA (Polyhydroxyalkanoate), and PCL (Polycaprolactone) have more aromatic components, so the decomposition progress rate is relatively slow.

The biodegradable resin composition of the present invention has good durability, mechanical strength and flexibility, can delay the biodegradation period during mulching, has excellent biodegradability and mechanical strength, has more improved flexibility, and has a delayed biodegradation period for various biodegradable agricultural mulching Can be used as a film.

The biodegradable mulching film of the present invention may add a chain extender and a hydrolysis resistance to the biodegradable resin composition.

It can be used to further improve water resistance by adding it if necessary because the rate of decomposition varies depending on the average temperature, precipitation, and sunlight of each region.

In this case, a chain extender containing an epoxy group may be used, and the epoxy group reacts with a carboxyl group and a hydroxyl group of poly(lactic acid) (PLA) to form a molecular weight and chain of PLA. A form with increased chain entanglement may be used. In addition, a form in which a branching reaction is performed on the PLA main chain may be used as a chain extender.

That is, in the biodegradable mulching film of this embodiment, the chain extender serves to increase the molecular weight through chain extension to improve tensile strength, tear strength, and the like. As such a chain extender, preferably, diisocyanate, an epoxy group copolymer, a hydroxycarboxylic acid compound, etc. may be used, but the present invention is not limited thereto. Chain extenders are used to increase the molecular weight and induce bonding between polymers to increase mechanical strength.

In addition, as the hydrolysis-resistant agent, a carbodiimide-based hydrolysis-resistant agent can be used. The carbodiimide-based hydrolysis resistant agent may have a weight average molecular weight of 50 to 250,000.

The anti-hydrolysis agent has a high water resistance improvement effect compared to other functional groups by reaction selectivity and high reactivity to an acid group, which is a factor for promoting hydrolysis, such as tensile strength, tear strength, etc. It serves to prevent deterioration of the mechanical properties of

That is, the hydrolysis resistance agent is not particularly limited as long as it is normally used as a hydrolysis resistance agent, and it can be used as long as the hydrolysis resistance agent exhibits excellent hydrolysis resistance in all kinds of polymers having an amide or ester group do. More preferably, an aromatic carbodiimide-type hydrolysis-resistant agent, polycarbodiimide, carbodiimide, oxazoline, or the like may be used.

The chain extender and the hydrolysis resistance agent are preferably blended in an amount of 0.5 to 3 parts by weight, respectively, based on 100 parts by weight of the biodegradable resin. At this time, when it is less than 0.5 parts by weight, the water resistance becomes insignificant, and when it is used in excess of 3 parts by weight, the water resistance becomes excessively high and the decomposition is slowed down.

As the antioxidant, it is preferable to use an antioxidant consisting of a primary antioxidant including a phenolic antioxidant and a secondary antioxidant including a phosphorus antioxidant.

The antioxidant consisting of the primary antioxidant and the secondary antioxidant maintains the long-term physical properties of the film, serves to prevent crosslinking of the polymer, and is blended in 0.05 to 0.5 parts by weight based on 100 parts by weight of the biodegradable resin. Preferably, if the content of the antioxidant is less than 0.05 parts by weight, the antioxidant effect is insignificant and durability may be reduced, whereas if it exceeds 0.5 parts by weight, blooming may occur and biodegradability may be reduced. Here, blooming may refer to a phenomenon in which the compounding agent seeps out on the surface of the film and a flower pattern is drawn.

As the phenolic antioxidant included in the primary antioxidant, SONGNOX 1076 / 1010 / 1024 / 1077 manufactured and sold by Songwon Industries and ADK STAB AO-60 manufactured by Adeka Fine Chemical Korea can be used, and limited thereto. it doesn't happen

Phosphorus-based antioxidants included in the secondary antioxidant include SONGNOX 6260 / 1680 / DHOP manufactured and sold by Songwon Industries, and ADK STAB 2112 manufactured by Adeka Fine Chemical Korea, and any one or two or more selected from these groups. this can be used

Preferably, the UV absorber and the light stabilizer are each 0.1 to 0.9 parts by weight based on 100 parts by weight of the biodegradable resin. When exposed, the durability of the mulching film may be reduced, whereas if the content exceeds 0.9 parts by weight, problems such as mechanical strength and biodegradability may occur.

The UV absorber serves to absorb UV rays so that UV rays do not come into contact with the material, and the light stabilizer serves to prevent the mulching film from being decomposed by exposure to UV rays for a long time. UV absorbers include Tinuvin 1130 / 326 / 327 / 328 / 571 / P and Uvinul 3000 / 3008 / 3040, and light stabilizers include Tinuvin 111 / 123 / 144 / 770 and Cyasorb 3346 / 3853S, any one of them or a combination of two or more, but is not limited thereto.

In addition, calcium carbonate, talc, carbon black, bentonite, silica, mica, silica, wood powder, chalk, wollas-tonite as a reinforcing filler to improve mechanical and thermal properties or workability of the biodegradable composition At least one inorganic material selected from (Woolas-tonite), diatomaceous earth, and the like may be added. In this case, the added inorganic material may be used for the purpose of improving physical properties and processability of the mulching film to be manufactured, and reducing unit cost.

The biodegradable mulching film of the present invention made from the above composition is preferably composed of an acid value of 0.5 to 2.0. If the acid value is less than 0.5, the biodegradation rate of the film is slow and the film is not decomposed even after harvesting the crop. This prevents the soil from maintaining its temperature.

The biodegradable mulching film of the present invention has good adaptability depending on the type of crop and the growth period (for example, 3 months, 6 months, 9 months) because the biodegradability rate is delayed with an acid value of 0.5 to 2.0, and the growth rate and yield of crops are affected. does not affect

The acid value is expressed in mg unit of the amount of potassium hydroxide (KOH: Potassium Hydroxide) required to neutralize the acidic component of 1 g of the sample, and the acid value is controlled by the addition of potassium hydroxide (KOH) used as a catalyst Decomposition stability is excellent as the acid value is lower, and the acid value is determined by an alkali catalyst.

As the alkali catalyst, in addition to potassium hydroxide (KOH), sodium hydroxide, calcium hydroxide, sodium carbonate anhydrous, potassium carbonate anhydrous, etc. It is determined by the mixing of more than one species, so that the acid value can be easily controlled.

Furthermore, the present invention provides a method for manufacturing a biodegradable mulching film having excellent water resistance.

Specifically, (1) a biodegradable resin composition and a slip agent, a primary antioxidant including a phenolic antioxidant, and a secondary antioxidant including a phosphorus antioxidant, a UV absorber and a light stabilizer Blending one or more additives selected from, (2) melt extrusion to form pellets, (3) annealing the extruded pellets, and (4) film extrusion step after the annealing.

In the above, the annealing step is a process of stirring the polymer in a hopper while maintaining it for a certain period of time under a constant high-temperature atmosphere, and then slowly cooling it to room temperature. improve the instability of

At this time, the annealing step of the present invention is performed by stirring the extruded pellets under high-temperature hot air conditions at 90° C. to 120° C. for 30 minutes to 50 minutes.

Through the annealing process, a strong bond is promoted between the surfaces of each inorganic and organic material having two or more different functional groups in the molecule, and the residual stress formed in the melt extrusion process is eliminated to promote the expression of maximum physical properties. can

In addition, if the residual stress inside the resin is removed through the annealing, the amount of additives can be reduced accordingly, and the dehumidification drying time can be shortened because the physical properties are relatively better. Therefore, compared to the conventional biodegradable mulching film, it is possible to secure competitiveness due to lower manufacturing cost, etc., and the preference is improved because water resistance is increased.

On the other hand, if the annealing temperature is less than 90 ℃, the durability and reliability of the product is relatively short and crystallinity is insufficient, and if it exceeds 120 ℃, there may occur a problem that the durability of the product is reduced.

The biodegradable film obtained by the above method can be processed into various forms such as agricultural mulching films, packaging films, shopping bags, and disposable trays.

Hereinafter, the present invention will be described in more detail through examples.

This example is for explaining the present invention in more detail, and the scope of the present invention is not limited by the following examples.

<Example 1>

PBAT (polybutylene adipate terephthalate) 74% by weight, PLA (polylactic acid) 8% by weight, calcium carbonate (CaCO ₃ ) with respect to 100 parts by weight of a biodegradable substrate consisting of 15% by weight and 3% by weight of carbon black, the primary 0.1 parts by weight of antioxidant (A0-60), 0.15 parts by weight of secondary antioxidant (A0-2112), 0.2 parts by weight of lubricant and slip agent (EBS, Ethylene Bis Stearamide), and 0.5 parts by weight of light stabilizer (Tinuvin 770) uniformly By mixing and compounding, a biodegradable resin composition was prepared. The extruder used was a twin extruder (L/D=36:1, Changseong P&R Machinery) with a screw diameter of 70 mm, and the biodegradable resin composition obtained after extruding at an extrusion speed of 255 rpm, a feed rate of 140 rpm, and a barrel temperature of 110 to 150 ° C. was subjected to an annealing process in which it was stirred in hot air at 110°C for 40 minutes, and then dehumidified and dried in a dehumidifying dryer for 4 hours (moisture: 300 ppm), and then a mulching film was prepared in a 50 mm film forming machine.

<Examples 2, 3 and Comparative Example 1>

A mulching film was prepared in the same manner as in Example 1 by adjusting the biodegradable resin composition as shown in Table 1 below.

division Example 1 Example 2 Example 3 Comparative Example 1 PBAT 74 79 60 65 PLA 8 10 15 12 TPS - - - 10 CaCO3 15 8 22 13 Carbon black 3 3 3 - Total (wt%) 100 100 100 100 Primary antioxidant 0.1 0.1 0.1 0.1 secondary antioxidant 0.15 0.15 0.15 0.15 light stabilizer 0.5 0.5 0.5 0.2 chain extender 0.3 0.35 0.5 0.3 slip agent 0.2 0.3 0.2 0.2

In Table 1, the unit of the biodegradable resin is weight %, and the remaining additives are parts by weight based on 100 parts by weight of the total amount of the biodegradable resin. Comparative Example 1 is a thermoplastic starch (TPS: A biodegradable mulching film was prepared in the same manner as in Example 1, except that thermoplastic Starch) was added.

*

<Experimental Example 1> Weed growth test evaluation

After mulching the biodegradable mulching films prepared in Example 1 and Comparative Example 1 in the open field, a weed growth test was performed for about 10 weeks.

1 is a test result during the crop growth period after mulching the biodegradable mulching film prepared by the manufacturing method according to Example 1 of the present invention in the field, and has much better water resistance than Comparative Example 1 of the following ( FIG. 2 ). and maintained the durability as an excellent film during the crop growth period, except for tearing caused by some elk footprints, and had the durability as a mulching film for 4 to 6 months, which is the normal cultivation period of crops, and 1 year after crop cultivation the following year. Afterwards, the film was completely disassembled and it was confirmed that the film was decomposed without any hindrance to planting new crops.

2 is a test result for weed growth during the biodegradation period after mulching the biodegradable mulching film prepared according to Comparative Example 1, and it was confirmed that the decomposition proceeded relatively quickly when TPS was used in the conventional manner, This is due to the use of amorphous starch that forms irregular branches, which has poor hydrolysis resistance and provides an active site that various microorganisms and enzymes can access sufficiently. linkage), so that the biodegradation rate proceeds rapidly.

Looking at the above results, the mulching film of Comparative Example 1 (FIG. 2) was quickly decomposed within a relatively short time of about 8 weeks, and the mulching film of this Example (FIG. 1) was decomposed even after 16 weeks except for the elk footprints. It can be seen that the water resistance is excellent as it endures well in a state where there is hardly any. That is, the mulching film of this embodiment does not use starch (TPS), and by undergoing a high-temperature annealing process in a method to minimize an amorphous region having an irregular, low orientation, and loose structure, and to increase crystallinity, it has water resistance under the same conditions. It can be seen that further improvement of

<Experimental Example 2>

After mulching the biodegradable mulching films prepared in Examples 1 to 3 and Comparative Example 1 in the open field, the temperature and humidity changes in the soil were measured during the tearing phenomenon and crop growth period.

In terms of the durability of the mulching film, the biodegradable mulching film prepared in Example 1 was not damaged even after 36 days, and the biodegradable mulching film of Comparative Example 1 started torn after 15 days, and most of it was damaged early. On the other hand, in the biodegradable mulching films prepared in Examples 2 and 3, the degree of breakage was controlled within 30 days, and it was confirmed that durability and water resistance were good. Table 2 shows this.

division Example 1 Example 2 Example 3 Comparative Example 1 Start date of damage 36 days 29th 30 days 15th

<Experimental Example 3> Changes in soil temperature, humidity, and weight of the coated biodegradable film were measured for each period. This is shown in Tables 3 to 5.

division term Example 1 Example 2 Example 3 Comparative Example 1 Temperature (℃) after mulching 29.08 28.00 32.54 28.13 1 week later 26.86 29.54 31.29 30.96 2 weeks later 33.36 34.16 33.59 30.69 after 4 weeks 25.47 25.79 27.55 26.25 after 6 weeks 28.68 24.22 28.53 30.06 after 8 weeks 23.88 20.38 23.87 20.78 after 10 weeks 22.17 19.35 21.78 18.38

division term Example 1 Example 2 Example 3 Comparative Example 1 Humidity(%) after mulching 87.90 95.10 94.86 89.70 1 week later 72.24 69.55 79.46 74.26 2 weeks later 81.64 85.51 90.40 72.72 after 4 weeks 86.78 83.33 91.51 85.63 after 6 weeks 79.96 89.04 92.68 83.73 after 8 weeks 87.33 82.07 90.15 82.82 after 10 weeks 85.41 80.84 86.87 78.84

division Example 1 Example 2 Example 3 Comparative Example 1 after mulching 9.424 11.309 11.104 10.318 1 week later 8.862 11.263 10.635 9.468 2 weeks later 8.731 10.373 10.223 8.763 after 4 weeks 8.652 9.999 9.398 8.082 after 6 weeks 8.421 9.743 9.043 7.545 after 8 weeks 8.169 9.113 8.889 7.132 after 10 weeks 7.589 8.787 8.456 6.761

Table 3 and FIG. 3 above show the temperature change of 10 cm in the soil under the mulching film after mulching, and Table 4 and FIG. 4 show the humidity change of 10 cm in the soil under the mulching film after mulching. And Table 5 and Figure 5 show the change in weight (unit: g) of the film (width 50cm, length 1m) according to the lapse of the period after mulching. From the results of Table 3, the soil temperature gradually decreased as the days passed, and from the results of Table 4, the soil humidity of Comparative Example 1 was the lowest, and this result is related to the breakage time of the mulching film. The soil humidity of Examples 1 and 3 was relatively high, and although there may be an effect of changes in external temperature and humidity, 85.41 to 86.87% (91.6% compared to the initial stage), which is generally higher than 78.84% (87.9% level compared to the initial level) of Comparative Example 1 ~97.2% level) was maintained.

As can be seen in Table 5, the results of Examples 1 to 3 resulted in a weight reduction of 19 to 23% after 10 weeks, whereas in Comparative Example 1, a weight reduction of 34% was achieved, so that the weight reduction of the film using the starch was reduced. It can be seen that the decomposition rate is fast as it is fast, and in the case of the same formulation of the additive for increasing water resistance, Examples 1 to 3 in which the crystallinity is increased through a high temperature annealing process and the residual stress inside the resin is resolved are more excellent Able to know.

Although the present invention has been described in detail through the above-described embodiments, it is apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical spirit of the present invention, and it is natural that such variations and modifications fall within the scope of the appended claims.

Claims (7)

(1) an antioxidant consisting of a primary antioxidant including a biodegradable resin and a chain extender, a hydrolysis resistance, a phenolic antioxidant and a secondary antioxidant including a phosphorus antioxidant, a UV absorber and a light stabilizer Combining one or more additives selected from
(2) melt extrusion to form pellets;
(3) annealing the extruded pellets, and
(4) prepared through the film extrusion step after the annealing,
The biodegradable resin is made of poly(butylene adipate-co-terephthalate) (PBAT), and polylactic acid (PLA),
The annealing step is characterized in that the extruded pellet is stirred in a high temperature atmosphere of 80 to 120 ° C. for 30 to 50 minutes to solve the residual stress inside the resin and to minimize the active site that microorganisms and enzymes can access. A biodegradable mulching film with excellent water resistance.
According to claim 1,
From the group consisting of an antioxidant, a UV absorber, and a light stabilizer comprising the biodegradable resin and a chain extender, a hydrolysis resistance, a primary antioxidant including a phenolic antioxidant and a secondary antioxidant including a phosphorus antioxidant Biodegradable mulching film with excellent water resistance, characterized in that the selected one or more additives are blended with the biodegradable resin to satisfy an acid value of 0.5 to 2.0.
According to claim 1,
A biodegradable mulching film with excellent water resistance, characterized in that 0.5 to 3 parts by weight of the chain extender is blended with respect to 100 parts by weight of the biodegradable resin.
According to claim 1,
The biodegradable mulching film with excellent water resistance, characterized in that 0.5 to 3 parts by weight of the hydrolysis resistance is blended with respect to 100 parts by weight of the biodegradable resin.
According to claim 1,
A biodegradable mulching film with excellent water resistance, characterized in that 0.05 to 0.5 parts by weight of the antioxidant consisting of the primary antioxidant and the secondary antioxidant is blended with respect to 100 parts by weight of the biodegradable resin.
According to claim 1,
The biodegradable mulching film with excellent water resistance, characterized in that 0.1 to 0.9 parts by weight of the UV absorber is blended with respect to 100 parts by weight of the biodegradable resin.
According to claim 1,
A biodegradable mulching film with excellent water resistance, characterized in that the light stabilizer is blended in an amount of 0.1 to 0.9 parts by weight based on 100 parts by weight of the biodegradable resin.

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