KR101294346B1 - Biodegradable Mulching Film - Google Patents

Abstract

The present invention relates to an agricultural mulching film of the present invention, in particular using no synthetic resin such as low density polyethylene (LDPE) or high density polyethylene (HDPE), but instead of polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS). ) Is used as a base polymer, and a biodegradable resin composition to which polylactic acid (PLA) is added to improve physical properties and an agricultural mulching film using the same.

Description

Biodegradable Mulching Film

The present invention relates to an agricultural mulching film of the present invention, in particular using no synthetic resin such as low density polyethylene (LDPE) or high density polyethylene (HDPE), but instead of polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS). ) Is used as a base polymer, and a biodegradable resin composition to which polylactic acid (PLA) is added to improve physical properties and an agricultural mulching film using the same.

Synthetic resin has been used as an indispensable material in real life due to various physical properties, stable supply, low price, and ease of manufacture and processing. However, when the synthetic resin is left in the natural environment, it does not decompose and remains semipermanently, which is a main cause of environmental pollution.

Agricultural mulching film is a film that covers the surface of agricultural crops such as furrows 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 increase of agricultural productivity in Korea, but it has been recognized as a factor that greatly pollutes the rural environment while leaving the soil due to the difficulty of recycling used waste.

In order to solve such problems, attempts have been made to use biodegradable resin films for field farming or rice planting. However, conventional biodegradable resin films also use synthetic resins such as polypropylene, polyethylene, or polystyrene as base polymers, Natural natural components are mixed as additives, and decomposition of natural components may be possible, but biodegradation of the base polymer itself is impossible. 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.

In addition, when biodegradable polymers are used as base polymers to biodegrade base polymers of synthetic resins, the physical properties of the biodegradable products themselves are weak, so the minimum strength is maintained to show the natural functions of products such as mulching films. There was a problem that it is difficult to secure the period.

In addition, the conventional biodegradable resin film has a problem in that the degradation time is too long in the biodegradation process or the decomposition efficiency is lowered to exhibit a substantially eco-friendly biodegradation effect.

As biodegradable resins, polyhydroxybutylate-valerate (PHBV) produced by microorganisms, polycaprolactone (PCL), an aliphatic polyester, polylactic acid (PLA), and diol-diexide aliphatic polyesters are used. . Diol-diacid based aliphatic polyesters include polybutylenesuccinate (PBS), polybutylene adipate (PBA), polybutylene adipate-terephthalate (PBAT), polybutylene succinate-adipate (PBSA) , Polybutylene succinate-terephthalate (PBST) and the like are used. When the molded article is manufactured only with biodegradable resin, since the price is high, researches for lowering the price and increasing biodegradability have been actively conducted.

The present invention has been made to solve the problems of the prior art,

An object of the present invention is to replace the synthetic resins such as LDPE, HDPE, etc., which were previously used as a main component of the base polymers such as mulching film, with biodegradable base polymers, so that even if they are buried in the soil, the base polymers can be naturally decomposed by the soil microorganisms. It is possible to provide a biodegradable resin composition that can be widely used in environmentally friendly film products and the like.

Another object of the present invention is to overcome the limitations in mechanical properties, such as when using the biodegradable polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS) as a base polymer in various working environments It is providing the biodegradable resin composition which can be used.

Still another object of the present invention is to provide a biodegradable mulching film that can maintain the strength up to a predetermined time and increase the efficiency of biodegradation after a certain period of time, thereby demonstrating both practicality and eco-friendliness.

The biodegradable resin composition of the present invention for solving the above problems

Polybutylene adipate terephthalate 20 wt% or more and 50 wt% or less, polybutylene succinate 30 wt% or more and 70 wt% or less and polylactic acid greater than 0 wt% and 10 wt% or less.

The biodegradable resin composition of the present invention may further comprise more than 0% by weight to 10% by weight of the natural polymer in order to provide suitable physical properties.

At this time, the natural polymer is preferably used in the form of a powder, the ideal size of the powder is 10 ~ 300㎛.

At this time, the natural polymer is preferably any one or a mixture of two or more selected from rice, rice husk, corn, potatoes, sweet potatoes, wheat, tapioca, or modified compounds thereof.

In addition, the biodegradable resin composition of the present invention may further include more than 0% by weight and 10% by weight or less of the processing functional agent for improving processing functionality such as blocking property / slip property.

In this case, the processing functional agent is a fine particle of the inorganic mineral, silica, diatomaceous earth, kaolin and talc and the like, preferably any one or a mixture of two or more selected from among them.

Agricultural mulching film of the present invention for solving the above problems,

Polybutylene adipate terephthalate 20 wt% or more and 50 wt% or less, polybutylene succinate 30 wt% or more and 70 wt% or less, polylactic acid greater than 0 wt% and 10 wt% or less.

Agricultural mulching film of the present invention may further comprise more than 0% by weight to 10% by weight of the natural polymer in order to provide suitable physical properties.

At this time, the natural polymer is preferably used in the form of a powder, the ideal size of the powder is 10 ~ 300㎛.

At this time, the natural polymer is preferably any one or a mixture of two or more selected from rice, rice husk, corn, potatoes, sweet potatoes, wheat, tapioca, or modified compounds thereof.

In addition, the agricultural mulching film of the present invention may further comprise more than 0% by weight and 10% by weight or less of the processing functional agent for improving processing functionality such as blocking property / slip property.

In this case, the processing functional agent is a fine particle of the inorganic mineral, silica, diatomaceous earth, kaolin and talc and the like, preferably any one or a mixture of two or more selected from among them.

The present invention can obtain the following effects by the above-described embodiment, the constitution described below, the combination, and the use relationship.

The present invention is exposed to the outside by preparing a base polymer using polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS), which are biodegradable compounds, without using any synthetic resin such as LDPE or HDPE. Even if it is buried in the soil, the base polymer can be naturally decomposed by the microorganisms of the soil, thereby providing a biodegradable resin composition that can be widely used in an environmentally friendly manner.

In addition, the present invention by additionally using PLA and natural polymer components, as well as PBAT, PBS, which is a biodegradable material, by supplementing the mechanical properties such as tensile force, PBAT, PBS alone has a limit to biodegradability that can be used in various working environments It provides a resin composition.

In addition, the present invention provides a biodegradable agricultural mulching film that can maintain the strength up to a certain time and increase the efficiency of biodegradation after a certain period of time can be used together with practicality and eco-friendliness.

1 is a photograph of the biodegradation process for each period of the mulching film according to Example 5 and Comparative Example 2 of the present invention.

The biodegradable resin composition of the present invention does not use synthetic resins, such as low density polyethylene (LDPE) or high density polyethylene (HDPE), which are widely used in conventional base polymers for manufacturing agricultural mulching films. Instead, the base polymer comprises polybutylene-co-adipate terephthalate (PBAT) and polybutylene succinate (PBS) in addition to polylactic acid (PLA). do. More specifically, it is characterized by including 20% by weight or more, 50% by weight or less of PBAT, 30% by weight or more, 70% by weight or less of PBS, and more than 10% by weight or less of PLA.

The PBAT is a soft biodegradable polymer, the biodegradable resin composition according to a preferred embodiment of the present invention contains 20 to 50% by weight of PBAT. If PBAT is used less than 20% by weight, film softness is insufficient, which causes problems in winding and film coating during processing, which is undesirable. It becomes unpreferable because it becomes severe and the problem that film control becomes difficult arises.

The polybutylene succinate (PBS) is a representative polycondensation aliphatic polyester, and is a heat resistant polymer having a relatively higher melting point than other polyesters synthesized from dihydric alcohols and divalent acids. PBS is easily degraded by microorganisms, but is hardly affected by hydrolysis and copolymerization of adipic acid significantly improves biodegradability.

The biodegradable resin composition according to a preferred embodiment of the present invention preferably contains 30 wt% or more and 70 wt% or less of PBS. If PBS is used at less than 30% by weight, biodegradability decreases, so that decomposition of the film after coating is delayed, so that the film is not decomposed until the next seeding, and it is not preferable. Degradation by the microorganism is so rapid that it is not desirable to maintain the function of the film for a desired period of time.

When the base polymer is composed of only PBAT and PBS, the film is easily torn in the longitudinal direction. However, in the preferred embodiment of the present invention, PLA is added to overcome the limitation of physical properties. Configure the base polymer for the composition.

PLA is a biodegradable thermoplastic plastic that has been widely used for bioabsorbable sutures or prosthetic implants, prosthetic supplies, drug delivery, and the like. Recently, PLA has been widely used for degradable plastics such as films and fibers There is an increasing interest in the use as a computer. PLA is characterized by high strength and thermoplasticity, good biodegradability and good human fitness but easily brittle and easily hydrolyzed.

Biodegradable resin composition according to a preferred embodiment of the present invention contains more than 0% by weight 10% by weight PLA. Since PLA has poor processability and flexibility, use of more than 10% by weight causes undesirable processing instability and increases the Brittleness characteristic of the film. In addition, PLA has high adhesiveness and if used in excess of 10% by weight, it may be undesirable because of the phenomenon of adhesion of the film during processing.

Biodegradable resin composition according to an embodiment of the present invention may further include a natural polymer component to provide suitable physical properties for plastic processing. In addition, natural polymers have excellent biodegradability at a relatively low price among biodegradable raw materials. It is also non-toxic because it is rich in resources such as rice and starch, is easy to supply, and is obtained directly from nature. When the natural polymer is added, the biodegradability of the resin composition prepared according to the present invention is improved, but work stability such as bubble molding is lowered.

As a natural polymer component applicable to the biodegradable resin composition according to the preferred embodiment of the present invention, any one or more mixtures selected from rice, rice husk, corn, potato, sweet potato, wheat, tapioca, or modified compounds thereof may be used. Can be used.

The natural polymer component thus selected can be used in the form of a powder according to the choice of a person skilled in the art. The suitable powder size of the natural polymer used in one embodiment of the present invention is preferably 10 ~ 300㎛, and may be used in the form of pellets after compounding the natural polymer in powder form with PBAT as the base resin.

Biodegradable resin composition according to a preferred embodiment of the present invention comprises more than 0% by weight 10% by weight of the natural polymer component. When the natural polymer is added, the biodegradability of the resin composition prepared according to the present invention is improved, but work stability such as bubble molding is lowered. If more than 10% by weight of the natural polymer may be used biodegradation may be promoted, but the problem that the bubble molding itself becomes difficult when forming the film.

The biodegradable resin composition according to an embodiment of the present invention may further include a processing functional agent in order to improve the properties in the case of manufacturing the film by processing the composition. Examples of processing functional agents applicable to the present invention include antiblocking agents or slip agents. Generally, when the film is formed, the bubbles are squeezed after the nip-roll step. At this time, the inner surfaces of the film do not fall off and do not fall off and do not slide smoothly with each other. One of the processing agents, anti blocking agents, solves this problem by improving the slip properties of the film.

The biodegradable resin composition according to a preferred embodiment of the present invention contains a functional agent in an amount of more than 0% by weight and less than 10% by weight. If the processing functional agent is used more than 10% by weight, it is not preferable because the problem of deterioration of the processability itself occurs due to excessive processing function improvement such as excessive slip property of the film. As the processing functional agent applicable as the anti-blocking agent to the present invention, any one or two or more selected from silica, diatomaceous earth, kaolin and talc, which are fine particles of an inorganic mineral, may be used.

The biodegradable resin composition according to an embodiment of the present invention may further include at least one additive selected from the group consisting of plasticizers, lubricants, minerals, and initiators.

The plasticizer penetrates between the natural polymer components to weaken the intermolecular hydrogen bond and to lose the inherent crystallinity of the natural polymer component, thereby converting the polymer into an amorphous state. The hydroxyl group of the obtained natural polymer component reacts with the terminal group of the compatibilizing agent to increase the lipophilicity, thereby improving the compatibility with the polylactic acid. The plasticizer may be selected from the group consisting of glycerin, sorbitol, 1,4-butanediol, ethylene glycol, glucose, propylene glycol, urea, polyethylene glycol and polypropylene glycol, more preferably glycerin .

The lubricant may be selected from the group consisting of wax, ethylenebisstearamide, mineral oil, and glycerin fatty acid ester, and mineral oil may be preferably used. The inorganic substance may be selected from the group consisting of talc, potassium carbonate, magnesium stearate, calcium sulfate, barium sulfate, clay, talc and pyrophyllite.

The initiator may be at least one selected from the group consisting of benzoyl peroxide, potassium persulfate, and dicumyl peroxide.

Biodegradable resin composition according to an embodiment of the present invention can be prepared by compressing a mixture of the above components. The extrusion conditions are not particularly limited, and may be preferably performed at an extrusion rate of 200 to 400 rpm, preferably about 300 rpm, and a feeding rate of 10 to 100 rpm, preferably about 40 rpm. In addition, a conventional extruder can be used as an extruder, For example, the twin extruder which has a three stage barrel can be used. At this time, the temperature of each barrel may be in the range of 50 ~ 230 ℃, preferably 130 ~ 200 ℃.

The present invention includes a film molded from the biodegradable resin composition described above. The film can be produced by molding the biodegradable resin composition described above using a conventional method, for example, an extrusion molding machine. Conditions for film forming are, for example, molding temperature (ie, barrel temperature and die temperature) 130 to 230 ° C, preferably 150 to 200 ° C, extrusion speed of about 500 rpm, raw material feeding rate of about 100 rpm, roll speed of about 200 rpm It can manufacture on conditions, such as these. The main use of the obtained film is an agricultural mulching film, and can be processed in various forms such as disposable food containers, hair growth pots, packaging cases and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are intended to illustrate the invention and should not be construed as limiting the invention.

Example 1

A biodegradable resin composition was prepared by mixing 35 wt% PBAT, 55 wt% PBS, and 10 wt% PLA. The extruder used was a twin extruder with a screw diameter of 44mm, the extrusion speed is 300rpm, the raw material input speed is 40rpm, the barrel temperature was 180 ℃. The properties of the obtained biodegradable resin composition were in the form of pellets.

The film was manufactured by the extrusion molding machine using the biodegradable resin composition obtained above, the barrel temperature was 140-180 degreeC, and the die temperature was 150-200 degreeC at the time of film molding. The extrusion speed was 500 rpm, the raw material input speed was 100 rpm, the roll speed was 200 rpm to prepare a film with a thickness of 0.03 mm.

Example 2

Biodegradable resin compositions and films were prepared in the same manner as in Example 1, using 30 wt% PBAT, 50 wt% PBS, 10 wt% PLA, and 10 wt% starch powder, which is a natural polymer.

Example 3

Biodegradable resin composition and film in the same manner as in Example 1, using 30 wt% PBAT, 50 wt% PBS, 10 wt% PLA, 5 wt% starch powder and 5 wt% antiblocking agent (silica) as a processing function Was prepared.

Example 4

Using 30 wt% PBAT, 50 wt% PBS, 5 wt% PLA, 10 wt% starch powder, and 5 wt% silica, a biodegradable resin composition and film were prepared in the same manner as in Example 1.

Example 5

Using 30 wt% PBAT, 55 wt% PBS, 5 wt% PLA, 5 wt% starch powder, and 5 wt% silica, a biodegradable resin composition and film were prepared in the same manner as in Example 1.

Comparative Example 1

Using 40 wt% PBAT, 30 wt% PBS and 30 wt% starch powder, a biodegradable resin composition and a film were prepared in the same manner as in Example 1.

Comparative Example 2

Unique, Inc. purchased Biodegradable Mulching Film, which is currently sold in Japan.

Comparative Example 3

Purchased FALCON-labeled biodegradable mulching film products for sale in Korea.

Comparative Example 4

The resin composition and the film were manufactured by the same method as Example 1 using the linear low density polyethylene (LLDPE) which is synthetic resin as a base polymer.

Comparative Example 5

The resin composition and the film were manufactured by the same method as Example 1 using the high density polyethylene (HDPE) which is synthetic resin as a base polymer.

Test Example 1. Property measurement

Films were prepared by an injection molding machine using the resin compositions prepared in Examples 1 to 5 and Comparative Examples 1 and 2. The temperature at the time of injection molding was 200 degreeC. Using the obtained film, a physical property test piece was obtained by using No. 1 mold specified in 7.6 Tensile strength and elongation test method of agricultural polyethylene film standard KS M 3503: 2002. Physical properties, ie tensile strength, tear strength and elongation, were measured using the obtained physical specimens.

Tensile strength and elongation were measured according to ASTM D638, and tear strength was measured according to ASTM D 1922.

The results are shown in Table 1 below.

Physical property measurement result division Tensile strength (kgf /) Tear strength (kgf /) Elongation (%) TD MD TD MD TD MD Example 1 190 315 138 116 499 201 Example 2 207 383 145 115 501 191 Example 3 356 465 192 164 720 228 Example 4 401 487 230 160 655 216 Example 5 457 508 248 167 756 235 Comparative Example 1 82 165 117 102 135 97 Comparative Example 2 269 344 195 182 490 313

As can be seen from the results of Table 1, in the case of Comparative Example 1 made of only PBAT and PBS without adding PLA, it was difficult to utilize as a mulching film for agriculture due to low overall physical properties. On the other hand, in the case of Example 1 in which PLA was added to improve physical properties, satisfactory results were obtained in tensile strength and longitudinal tearing.

In addition, in the case of Examples 2 to 5 in which the natural polymer powder was added to improve the physical properties, it could be confirmed that the tensile strength and the tear in the longitudinal direction were similar to those of Comparative Example 2, which is a ready-made product, or rather, showed more improved physical properties.

Test Example 2. Biodegradability test

The biodegradability was measured by coating the film prepared in Example 5 and Comparative Examples 2 to 5 to the actual soil. For this purpose, biodegradability was measured by visually observing the decomposition progress of the coated sheet at the initial stage of coating, 90 days after coating, and 180 days after coating.

As a result of the measurement, not only Comparative Example 3, which is known as a biodegradable mulching film product, but also Comparative Examples 4 and 5 using synthetic resin LLDPE or HDPE as the base polymer, no progress of decomposition could be visually confirmed after 180 days.

Particularly, the results of photographing the biodegradation process according to time periods of Comparative Example 2 and Example 5 prepared according to a preferred embodiment of the present invention, which are known to have excellent biodegradability, are shown in FIG. 1.

As can be seen in Figure 1, even after 180 days after coating the soil, the film produced according to Comparative Example 2 was not able to visually confirm the progress of decomposition. On the other hand, the film of Example 5 prepared according to the preferred embodiment of the present invention was a mold was propagated by the action of soil microorganisms.

Through the use of Experimental Example 1 and Experimental Example 2 according to a preferred embodiment of the present invention by using PLA as the base polymer for the resin composition and film as well as PBAT and PBS to improve the overall physical properties such as tensile strength and tearing in the longitudinal direction I could confirm it. In addition, by using a natural polymer in addition to such a resin composition and film was able to further improve the biodegradation, in particular it was confirmed that the effect on crop growth through the growth and modification of soil microorganisms.

Claims (12)

More than 0% by weight of polylactic acid and 10% by weight or less,
20 wt% or more and 50 wt% or less of polybutylene adipate terephthalate, and;
A biodegradable resin composition comprising 30 wt% or more and 70 wt% or less of polybutylene succinate. The method of claim 1,
Biodegradable resin composition, characterized in that it further comprises more than 0% by weight and 10% by weight or less of the natural polymer. The method of claim 2,
Wherein the natural polymer is any one or a mixture of two or more selected from rice, rice hull, corn, potato, sweet potato, wheat, tapioca, and modified compounds thereof. 4. The method according to claim 2 or 3,
The natural polymer is a biodegradable resin composition, characterized in that in the form of a powder having a particle diameter of 10 ~ 300㎛. The method of claim 1,
The biodegradable resin composition further comprising more than 0% by weight and 10% by weight or less of the processing functional agent. 6. The method of claim 5,
The processing functional agent is a biodegradable resin composition, characterized in that any one or a mixture of two or more selected from fine particles of inorganic minerals, silica, diatomaceous earth, kaolin and talc. 20 wt% or more and 50 wt% or less of polybutylene adipate terephthalate;
30 wt% or more and 70 wt% or less of polybutylene succinate, and;
Biodegradable agricultural mulching film comprising more than 0% by weight of polylactic acid and up to 10% by weight. 8. The method of claim 7,
Biodegradable agricultural mulching film, characterized in that it further comprises more than 0% by weight and 10% by weight or less of the natural polymer. The method of claim 8,
The natural polymer is biodegradable agricultural mulching film, characterized in that any one or a mixture of two or more selected from rice, rice husk, corn, potatoes, sweet potatoes, wheat, tapioca, or modified compounds thereof. 10. The method according to claim 8 or 9,
The natural polymer is a biodegradable agricultural mulching film, characterized in that in the form of a powder having a particle diameter of 10 ~ 300㎛. 8. The method of claim 7,
A biodegradable agricultural mulching film, further comprising more than 0% by weight and 10% by weight or less of the processing functional agent. 12. The method of claim 11,
The processing functional agent is a biodegradable agricultural mulching film, characterized in that any one or a mixture of two or more selected from fine particles of inorganic minerals silica, diatomaceous earth, kaolin and talc.

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