KR20210005339A - 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 hydrolysis resistance and a method for manufacturing the same. The method for manufacturing a biodegradable mulching film having excellent hydrolysis resistance includes: selecting heterogeneous biodegradable resins having a different biodegradation rate to allow a delay in biodegradation period upon the mulching; blending the biodegradable resins with at least one additive selected from the group consisting of a chain extending agent, anti-hydrolysis agent, antioxidants including a primary antioxidant containing a phenolic antioxidant and a secondary antioxidant containing a phosphorus-based antioxidant, UV absorbing agent, and a light stabilizer, followed by compounding; and removing residual stress under a predetermined high-temperature atmosphere and carrying out annealing to increase the crystallinity.

Description

Biodegradable mulching film with excellent water resistance and its manufacturing method {BIODEGRADABLE MULCHING FILM HAVING THE IMPROVED ANTI-HYDROLYSIS PROPERTY AND MANUFACTURING METHOD THEREOF}

The present invention relates to a biodegradable mulching film having excellent water resistance and a method of manufacturing the same, and more particularly, by selecting different types of biodegradable resins having different biodegradation rates to delay the biodegradation period during mulching, and a chain extender to the biodegradable resin. , A hydrolysis-resistant agent, a primary antioxidant including a phenolic antioxidant and a secondary antioxidant including a phosphorus antioxidant, a UV absorber, and a light stabilizer. Afterwards, 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 of manufacturing the same.

Mulching refers to work carried out for the purpose of preventing soil erosion, maintaining soil moisture, temperature control, weed control, soil infectious pathogens, soil contamination, etc. by covering the land where crops are grown with vinyl or straw. .

Since the development of agricultural mulching film, it has been used in primitive agricultural cultivation methods such as vinyl houses, vinyl tunnels, vinyl caps, and suppression of weed growth, thereby helping farmers, who are producers, solve high incomes and labor shortages. It can be said that the availability of fruits and vegetables at low prices has been an opportunity for a major agricultural revolution, but agricultural films are widely distributed to each farm as the years go by, and the usage is increasing rapidly.

The incineration of waste vinyl generated during the farming process and landfill in the soil cause agricultural land pollution and damage to the rural landscape, and due to the aging of the rural population, the rate of waste vinyl collection has decreased, preventing it from being collected. They are neglected and buried in the soil, which may interfere with the growth of crops and cause pollution, and are not good in terms of aesthetics.

In addition, even the collected waste vinyl can be recycled only after undergoing various processes such as washing and drying foreign substances, but the recycling treatment cost is more expensive than recycled products, so it is a passive situation for reprocessing, and agricultural mulching film is collected and incinerated after use. Or, as the treatment is carried out by a burial method, dust and toxic gases are released, causing various secondary pollution, and the severity is increasing day by day.

The development and dissemination of eco-friendly agricultural mulching film is a combination of biodegradable polymers, suitable additives, and antioxidants. It is efficient and has advantages such as weed control, pest prevention effect, and geothermal preservation, and biodegradation occurs during disposal, so it is necessary to commercialize it as an agricultural material necessary for eco-friendly agriculture.

The goal of the mulching film development market is to develop eco-friendly agricultural films that are environmentally friendly and biodegradable, but currently used agricultural mulching films are made of polyethylene (PE) based on the petrochemical product, Low Density Polyethylene (LDPE). Films are mostly used, and hardly decomposable mulching films that are not collected remain in the soil, causing soil contamination in the long term and a decrease in intellectual power, and in the longer term, causing a decrease in production.

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

As a representative biodegradable plastic material, polylactic acid (PLA: Poly Lactic Aicd) is produced as a polymer by separating starch from corn and condensing lactic acid fermented with glucose, and is produced by microorganisms (bacteria, fungi, algae, etc.). A material that is completely biodegradable with water (H ₂ O) and carbon dioxide (CO ₂ ) and has been approved as a biodegradable raw material that is harmless to humans and the environment by the U.S. Food and Drug Administration (FDA), the Korean Food and Drug Administration, Canada, Japan, and Germany to be.

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, so the range of use as a film is bound to be limited. .

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, and is coated on the bottom of the soil because it can biodegrade not only the biodegradable compound but also the base polymer. It has been reported that it can suppress the growth of weeds and prevent pests and pests, so that it can significantly reduce the use of pesticides, but also prevent environmental pollution because it is decomposed by microorganisms in the natural state after a certain period of time.

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), and polypropylene (PP: Polypropylene). A mixture of these is used, and a more preferred embodiment provides a mulching film extruded by mixing 12% by weight of LDPE and 48% by weight of LLDPE as a plastic resin in 40% by weight of a biodegradable compound.

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

Therefore, such a film can be called a biodegradable mulching film rather than a degradable mulching film.When used continuously, the residues remain in the soil, which can cause secondary pollution of farmland and a decrease in agricultural production due to a decrease in intellectual power. have.

Patent Document 3 is an invention of a biodegradable double film using a biodegradable WPC (Wood Polymer Composition), the biodegradable resin is polylactic acid (PLA) 50-75% by weight, 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, and it is not completely biodegradable because it uses non-degradable polyurethane (PU) resin. Can provide a cause.

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

Korean Patent No. 0545271 (announced on January 24, 2006) Korean Patent No. 0993886 (announced on June 24, 2009) Korean Patent No. 1176604 (announced on August 23, 2012)

Accordingly, the present inventors did not use any non-degradable resin at all in accordance with the demand for increased water resistance required for conventional biodegradable mulching films, but used only internationally certified biodegradable resins, but selected heterogeneous biodegradable resins with different biodegradation rates when mulching. The biodegradation period can be controlled, and various functional additives such as primary and secondary antioxidants, thermal stabilizers, chain extenders, hydrolysis-resistant agents, slip agents, and dispersants are used in the selection of raw materials and during extrusion processing. In order to prevent moisture moisture and increase the durability of the biodegradable mulching film to play an important role in mulching during the desired crop growth period, the process of optimal material selection, mixing ratio, order of work, temperature conditions, etc. The invention was completed.

An object of the present invention is to provide a biodegradable mulching film excellent in water resistance.

Another object of the present invention is to provide a method for producing a biodegradable mulching film in which durability and water resistance are optimized by compounding and extruding into an optimal raw material selection and blending and processing through an annealing process of pellets.

In order to achieve the above object, (i) a biodegradable resin composition (ii) a slip agent, a primary antioxidant including a phenolic antioxidant, and a secondary antioxidant comprising a phosphorus antioxidant, an ultraviolet ray (UV) ) A biodegradable mulching film resin with excellent water resistance is melt-extruded by blending at least one additive selected from the group consisting of an absorbent and a light stabilizer to satisfy an acid value of 0.5 to 2.0, and (iii) melt extrusion through a high-temperature annealing process of the extruded resin. The active site (microorganism: bacteria, fungi, fungi, etc.) and enzymes in the soil can sufficiently access various microorganisms (microorganisms: bacteria, fungi, fungi, etc.) in the soil by maximizing the expression of physical properties by resolving residual stress inside the resin formed during the process site) to prevent hydrolysable linkage early, 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 (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 biodegradable resin consisting of poly(butylene adipate-co-terephthalate), PBAT, which is an aliphatic-aromatic polyester resin Is to use.

The antioxidant consisting of the first 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 formulated in an amount of 0.1 to 0.9 parts by weight, respectively, based on 100 parts by weight of the biodegradable resin.

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

In the above, the annealing step is performed by stirring the extruded resin pellets at a high temperature of 90 to 120°C and minimizing the amorphous region having an irregular and loose structure between molecular chains to increase the degree of crystallinity and melt It is carried out as a process that effectively removes residual stress caused by frictional heat and pressure between extrusions and irregular cooling rates between the resin and the outside, thereby improving the bonding strength 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, as an antioxidant, a UV absorber, and a light stabilizer. It is possible to provide a mulching film having excellent water resistance by mixing one or more additives selected from the group consisting of, and maximizing the physical properties of the biodegradable resin composition through annealing process of the compounded pellet at a constant high temperature.

In addition, through the high-temperature annealing process of the extruded resin, it maximizes the expression of physical properties and increases the crystallinity by resolving residual stress inside the resin formed during the melt extrusion process, thereby increasing the degree of crystallinity and various microorganisms (such as bacteria, fungi, fungi, etc.) By minimizing the active site that can be accessed sufficiently, hydrolysable linkage can be prevented early to provide a film with improved water resistance compared to the existing biodegradable mulching film, and annealing Through the process, the moisture content decreases, so it is possible to secure competition that can shorten the dehumidification drying time by more than 70%.

When the biodegradable mulching film of the present invention is buried in the soil, the polymer becomes low molecular weight by water, microorganisms, and enzymes, and is completely biodegraded by the metabolism of the microorganisms, and the soil microorganisms are activated. It can provide 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 it after harvesting the crop, thus saving labor, greatly reducing the social cost required for the collection and treatment of agricultural waste vinyl, and without illegal incineration. In addition, even during incineration, the generation of environmental hormones and harmful gases is less than that of existing polyethylene (PE), and the effect of reducing the generation of carbon dioxide, one of the causes of global warming, can be expected by 30% or more.

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 of 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 humidity change of 10 cm in the soil under the mulching film after mulching,
5 shows the weight change of the film (50 cm wide, 1 m long) according to the lapse of the period after mulching,
6 shows the biodegradation test report of the Institute for Chemical Convergence Testing.

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

The present invention comprises (i) a biodegradable resin composition and (ii) a slip agent, a primary antioxidant comprising a phenolic antioxidant, and a secondary antioxidant comprising a phosphorus antioxidant, and a UV absorber and a light stabilizer. One or more additives selected from the group consisting of are blended to provide a biodegradable mulching film with excellent water resistance that satisfies an acid value of 0.5 to 2.0, and (iii) a high temperature annealing process of the extruded resin eliminates residual stress formed in the melt extrusion process. It is hydrolyzed by enzymatic cleavage in the polymer backbone by minimizing the active site where various microorganisms (microorganism: bacteria, fungi, fungi, etc.) and enzymes in the soil can have sufficient accessibility by increasing the crystallinity. By preventing hydrolyable linkage early, it is possible to provide a film with improved water resistance compared to the existing biodegradable mulching film.

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

More preferably, polylactic acid (PLA) is included as a first component, and an optimal aliphatic-aromatic polyester resin having a low acid value and a low melt flow index (MI) is included 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 a diol and carboxylic acid group having 1 to 6 -CH ₂ -introduced between alcohol groups, or -CH between terephthalate and carboxylic acid group _{It includes} an aliphatic-aromatic polyester condensation-polymerized with a diacid having 1 to 6 of ₂ -being introduced and a copolymer 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 is somewhat inferior in mechanical strength, but it is a polymer of a polyester-based thermoplastic polymer and microbes in the soil by hydrolysis. Although it has biodegradability that is decomposed into carbon dioxide and water by the like, it has more aromatic components than other aliphatic polyesters such as PBS (Polybutylene Succinate), PHA (Polyhydroxyalkanoate), and PCL (Polycaprolactone), so the decomposition process is relatively slow.

The biodegradable resin composition of the present invention has good durability, mechanical strength and flexibility, and can delay the biodegradation period when mulching, and has excellent biodegradability and mechanical strength, but has improved flexibility and a delayed biodegradation period, resulting in 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 resistant agent to the biodegradable resin composition.

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

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

That is, in the biodegradable mulching film of this embodiment, the chain extender serves to improve tensile strength and tear strength by increasing the molecular weight through chain extension. As such a chain extender, a diisocyanate, an epoxy group copolymer, a hydroxycarboxylic acid compound, and the like may be preferably 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, a carbodiimide-based hydrolyzing agent can be used as the hydrolyzing agent. The carbodiimide-based hydrolyzing 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 due to the reaction selectivity and high reactivity to the acid group, which is a factor for accelerating hydrolysis, such as tensile strength, tear strength, etc. It serves to prevent the mechanical properties of the product from deteriorating.

That is, there is no particular limitation as long as the hydrolyzing agent is usually used as a hydrolyzing agent, and it can be used as long as the hydrolyzing agent exhibits excellent hydrolysis resistance in all kinds of polymers having an amide or ester group. Do. More preferably, an aromatic carbodiimide type hydrolysis agent, polycarbodiimide, carbodiimide, oxazoline, and the like may be used.

It is preferable that the chain extender and the hydrolysis resistant agent are 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, if it is less than 0.5 parts by weight, the water resistance becomes insignificant, and if it is used in excess of 3 parts by weight, there is a problem that the water resistance is excessively increased and decomposition is slow.

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 first 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 an amount of 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 may be insignificant and durability may be deteriorated. On the other hand, if it exceeds 0.5 parts by weight, blooming may occur and biodegradability may decrease. Here, blooming may refer to a phenomenon in which a compounding agent seeps out of the film surface and a flower-shaped 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 may be used, and limited thereto. It doesn't work.

Phosphorus-based antioxidants included in the secondary antioxidants 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 Can be used.

The UV absorber and the light stabilizer are preferably 0.1 to 0.9 parts by weight, respectively, based on 100 parts by weight of the biodegradable resin, and when the content is less than 0.1 parts by weight, dispersion is insufficient during the extrusion process and the UV blocking effect is insignificant or for a long time When exposed, the durability of the mulching film may be deteriorated. On the other hand, when the content exceeds 0.9 parts by weight, problems such as mechanical strength and biodegradability may decrease.

The UV absorber absorbs ultraviolet rays so that the ultraviolet rays do not touch the material, and the light stabilizer serves to prevent the mulching film from being decomposed by exposure to ultraviolet 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, and any of these Or it may include a combination of two or more, but is not limited to these.

In addition, calcium carbonate, talc, carbon black, bentonite, silica, mica, silica stone, wood powder, choke, ullas-tonite as a reinforcing filler to improve mechanical and thermal properties or workability of the biodegradable composition (Woolas-tonite), at least one or more inorganic materials selected from diatomaceous earth may be added. In that case, the added inorganic material may be used for the purpose of improving physical properties and processability of the mulching film to be produced, 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 above acid value is less than 0.5, the biodegradation rate of the film is slow, so that the film is not decomposed even after harvesting the crop, and if the acid value exceeds 2.0, the biodegradation rate of the film is very fast, and decomposition begins before the crop sprouts. It becomes impossible to maintain the soil temperature.

The biodegradable mulching film of the present invention has an acid value of 0.5 to 2.0, and the biodegradability rate is delayed, so it has good adaptability according to the type and growth period (for example, 3 months, 6 months, 9 months), and is suitable for the growth rate and yield of the crop. Does not affect.

The acid value is expressed in mg units of the amount of potassium hydroxide (KOH: Potassium Hydroxide) required to neutralize the acidic component of 1 g of a sample, and the acid value is adjusted by the addition of potassium hydroxide (KOH) used as a catalyst. The lower the acid value, the better the decomposition stability, 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, and potassium carbonate anhydrous may be used. It is determined by mixing more than one species, and because of this, it is easy to control the acid value.

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

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

In the above, the annealing step is a process of slowly cooling the polymer to room temperature after stirring while maintaining it for a certain period of time under a constant high-temperature atmosphere in a hopper, and pellets generated by residual stress generated in the melt extrusion process through annealing and non-uniform cooling. Improve the instability of

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

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

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

On the other hand, when the annealing temperature is less than 90°C, the durability and reliability life of the product becomes relatively short and crystallinity is insufficient, and when it exceeds 120°C, the durability of the product may decrease.

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

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 ) 15% by weight, based on 100 parts by weight of the biodegradable substrate consisting of 3% by weight of carbon black, 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) are uniform Mixing and compounding to prepare a biodegradable resin composition. The used extruder is a twin extruder (L/D=36:1, Changsung P&R Co., Ltd.) with a screw diameter of 70 mm, extruding at an extrusion speed of 255 rpm, a feed rate of 140 rpm, and a barrel temperature of 110 to 150 °C. After the annealing process of stirring for 40 minutes in a high temperature hot air of 110 ℃ dehumidified drying for 4 hours in a dehumidifying dryer (moisture 300ppm) to prepare a mulching film in a 50mm film molding machine.

<Examples 2 and 3 and Comparative Example 1>

The biodegradable resin composition was adjusted as shown in Table 1 below to prepare a mulching film in the same manner as in Example 1.

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 (% by weight) 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% by 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) to promote biodegradability in the compounding process. Thermoplastic Starch) was added to prepare a biodegradable mulching film in the same manner as in Example 1.

<Experimental Example 1> Weed growth test evaluation

After mulching the biodegradable mulching films prepared in Example 1 and Comparative Example 1 in a 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 is much better in water resistance than Comparative Example 1 of the following (FIG. 2) It maintained the durability as an excellent film during the crop growth period, and had durability as a mulching film for 4-6 months, which is a general crop cultivation period, except for tearing caused by some elk footprints. Afterwards, the film was completely decomposed, and the decomposition could be confirmed without any hindrance to planting a new crop.

2 is a test result for the growth of weeds during the biodegradation period after mulching the biodegradable mulching film prepared according to Comparative Example 1, it was confirmed that the decomposition proceeded relatively quickly when TPS was used in the conventional manner. This is because of the use of amorphous starch that forms irregular branches, it has poor hydrolysis resistance and provides an active site that allows various microorganisms and enzymes to sufficiently access, thereby accelerating the cleavage by enzymes to the polymer backbone and thereby hydrolysing it. linkage) was found to accelerate the biodegradation rate.

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 other than the elk footprint. It can be seen that the water resistance was excellent by holding up well with little or no. That is, the mulching film of the present embodiment minimizes the amorphous region having an irregular, low orientation, and loose structure without using starch (TPS), and is water-resistant under the same conditions by going through a high-temperature annealing process to increase crystallinity. It can be seen that it further improves.

<Experimental Example 2>

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

Durability, as viewed from the breakage date of the mulching film, was not damaged even after 36 days of the biodegradable mulching film prepared in Example 1, and the biodegradable mulching film of Comparative Example 1 started torn in 15 days, and most were damaged early. On the other hand, the biodegradable mulching film prepared in Examples 2 and 3 was confirmed to have good durability and water resistance because the degree of damage was controlled within 30 days. This is shown in Table 2.

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 4 weeks later 25.47 25.79 27.55 26.25 6 weeks later 28.68 24.22 28.53 30.06 8 weeks later 23.88 20.38 23.87 20.78 10 weeks later 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 4 weeks later 86.78 83.33 91.51 85.63 6 weeks later 79.96 89.04 92.68 83.73 8 weeks later 87.33 82.07 90.15 82.82 10 weeks later 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 4 weeks later 8.652 9.999 9.398 8.082 6 weeks later 8.421 9.743 9.043 7.545 8 weeks later 8.169 9.113 8.889 7.132 10 weeks later 7.589 8.787 8.456 6.761

Table 3 and FIG. 3 above show the temperature change by period of 10 cm in the soil under the mulching film after mulching, and Table 4 and FIG. 4 are the results showing the humidity change by period of 10 cm in the soil under the mulching film after mulching. And Table 5 and Figure 5 show the weight change (unit: g) for each period of the film (width 50 cm, length 1 m) according to the lapse of the period after mulching. From the results of Table 3, the temperature of the soil 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 was related to the breakage time of the mulching film.

On the other hand, the soil humidity of Examples 1 and 3 was relatively high, and although there may be influences of changes in external temperature and humidity, it is 85.41 to 86.87% (which is generally higher than 78.84% (87.9% compared to the initial level)) of Comparative Example 1. 91.6%~97.2% level compared to the initial period).

As can be seen in Table 5, the results of Examples 1 to 3 showed a weight reduction of 19 to 23% after 10 weeks, whereas in the case of Comparative Example 1, the weight of the film using starch was reduced by 34%. It can be seen that the decomposition rate 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 are resolved are more excellent Able to know.

In the above, the present invention has been described in detail through the above-described embodiments, but it is obvious to those skilled in the art that various modifications and modifications are possible within the scope of the technical idea of the present invention, and it is natural that such modifications and modifications belong to the appended claims.

Claims (10)

(1) The group consisting of antioxidants, UV absorbers, and photostabilizers consisting of primary antioxidants including biodegradable resins and chain extenders, hydrolysis resistance, phenolic antioxidants, and secondary antioxidants including phosphorus antioxidants Blending one or more additives selected from,
(2) melt extrusion to form pellets,
(3) annealing step of the extruded pellet, and
(4) Film extrusion step after the annealing
A method of manufacturing a biodegradable mulching film with excellent water resistance. The method of claim 1, wherein the annealing step is performed by stirring the extruded pellet in a high-temperature atmosphere of 80 to 120° C. for 30 to 50 minutes to relieve residual stress inside the resin, and to establish an active site through which microorganisms can access the enzyme. Method for producing a biodegradable mulching film excellent in water resistance, characterized in that to minimize. Antioxidants, UV absorbers, and photostabilizers consisting of (i) biodegradable resins, and (ii) primary antioxidants including chain extenders, hydrolysis resistant agents, phenolic antioxidants and secondary antioxidants including phosphorus antioxidants A biodegradable mulching film having excellent water resistance in which at least one additive selected from the group consisting of is blended with the biodegradable resin to satisfy an acid value of 0.5 to 2.0. The method of claim 3, wherein the biodegradable resin is poly(butylene adipate-co-terephthalate), PBAT, poly(butylene succinate, PBS) and polylactic acid ( Polylactic acid, PLA) is a biodegradable mulching film having excellent water resistance, characterized in that at least two or three selected from the group consisting of. [4] The biodegradable mulching film according to claim 3, wherein the biodegradable resin is a heterogeneous biodegradable resin composed of a first component of polylactic acid (PLA) and an aliphatic-aromatic polyester resin. The biodegradable mulching film of claim 3, wherein the chain extender is blended with 0.5 to 3 parts by weight based on 100 parts by weight of the biodegradable resin. [4] The biodegradable mulching film of claim 3, wherein 0.5 to 3 parts by weight of the hydrolyzable agent is mixed with respect to 100 parts by weight of the biodegradable resin. The biodegradable mulching film of claim 3, wherein an antioxidant consisting of the primary antioxidant and the secondary antioxidant is blended in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the biodegradable resin. The biodegradable mulching film of claim 3, wherein the UV absorber is blended in an amount of 0.1 to 0.9 parts by weight based on 100 parts by weight of the biodegradable resin. The biodegradable mulching film of claim 3, wherein 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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