KR102198513B1 - Preperation method of resin pellet for mulching film of controlling biodegradation rate and biodegradable mulching film using the same - Google Patents

Abstract

The present invention relates to a resin composition for a mulching film capable of controlling the biodegradation rate, and a biodegradable mulching film using the same, and more particularly, to a surface-modified biomass with improved dispersibility with a polyolefin-based resin and oxidative biodegradation for controlling the rate of biodegradation It relates to a resin composition for a mulching film capable of controlling the rate of biodegradation by including an agent, and a biodegradable mulching film using the same.

Description

(Preperation method of resin pellet for mulching film of controlling biodegradation rate and biodegradable mulching film using the same}

The present invention relates to a method for producing a resin pellet for a mulching film capable of controlling a biodegradation rate, and a biodegradable mulching film using the same, and more particularly, to a surface-modified biomass with improved dispersibility with a polyolefin-based resin and a biodegradation rate control It relates to a method for producing a resin pellet for a mulching film capable of controlling a biodegradation time by including an oxidation accelerator, and a biodegradable mulching film using the same.

Mulching films can be classified into petroleum-based synthetic resins, which use a general blow film, an oxidation biodegradable film produced by adding an oxidation accelerator to a general synthetic resin film, and a biodegradable film product using a hydrolyzed resin as a base material. In the case of general synthetic resin film, the cost is low, but there is a problem in that social costs and environmental burdens occur in collection and treatment after cultivation. On the other hand, biodegradable film can be treated more environmentally than normal film, but it is not possible to control the decomposition period according to the growth cycle of plants because it is prematurely biodegraded according to external conditions such as the disadvantage of expensive price and organic matter in the soil.

Currently, as materials for biodegradable mulching films, aliphatic polyesters such as PBAT (poly butylene adipate-co-terephthalate) are widely used, and recently, a general-purpose polymer used in the past is used as a film using biodegradable polyester. Research to improve the physical properties of biodegradable polyester, such as mechanical strength and hydrolysis properties, is being conducted. The PBAT has excellent mechanical properties and moldability, but, like other biodegradable polymer resins, the raw material is expensive, so there is a limit to the expansion of its use. Therefore, in recent years, the decomposition rate of the polymer is controlled by using an oxidation accelerator in the product using a resin compounded with biomass such as soybean hull in polyethylene, which is a general-purpose polymer, but it lacks biodegradability and does not effectively exhibit the function of degradable mulching film. I can't. Therefore, in order to develop a biodegradable mulching film that has excellent mechanical properties and is economical, it is urgent to develop a mulching film that can easily control the biodegradation time by using the compounding properties of existing biodegradable resins, polyethylene, biomass and oxidation accelerators.

Korean Patent Registration No. 10-1294346 (Registration factor 2013.08.01)

In order to solve the above problems, the present invention includes a surface-modified biomass having improved dispersibility with a polyolefin-based resin, a compatibilizer for compatibility with a polyolefin-based resin, and an oxidation accelerator for controlling the rate of biodegradation. It is an object of the present invention to provide a method of manufacturing a resin pellet for a mulching film capable of time control and a biodegradation time control mulching film using the same.

To this end, the present invention in the resin composition for a mulching film,

100 parts by weight of a biodegradable polymer resin, 10 to 35 parts by weight of a polyolefin resin, 15 to 25 parts by weight of a surface-modified biomass, 3 to 7 parts by weight of a compatibilizer for compatibility between the biodegradable polymer resin and the polyolefin resin, and It characterized in that it contains 0.025 to 0.5 parts by weight of an oxidation accelerator for controlling the rate of biodegradation based on 100 parts by weight of the polyolefin-based resin.

The biodegradable polymer resin is polybutylene adipate terephthalide (PBAT), thermoplastic starch (thermo plastic starch), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adi It may be one or more selected from the group consisting of pate (PBSA), polybutylene succinate-terephthalate (PBST) rehydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), and polylactic acid (PLA). .

The polyolefin resin may be at least one selected from the group consisting of LDPE, HDPE, MDPE, LLDPE, VLDPE, PP, PVC, EVA, vinyl acetate, and copolymers thereof.

The surface-modified biomass may be obtained by hydrophobizing at least one of hydroxyl groups (-OH groups) of a cellulose unit with silane using a silane coupling agent.

The surface-modified biomass may be herbaceous biomass including rice straw, barley straw, wheat straw, rice husk, corn stalks and leaves, soybean stalks, bean pods, onion stalks, sweet potato stalks, pine needles, or coffee grounds.

The compatibilizer may be at least one selected from the group consisting of inorganic fillers, glycidyl methacrylate, ethylene vinyl alcohol (EVA), polyvinyl alcohol (PVA), ethylene vinyl acetate, SEBS, maleic anhydride and MAP resin.

The inorganic filler may be at least one nano-sized powder selected from the group consisting of calcium carbonate, glass fiber, talc, mica, silica stone, clay powder, wollastonite, talc, kaolin powder, silica, mica, kaolin, and titanium dioxide. .

The oxidation accelerator may be a compound containing a divalent transition metal cation, and the transition metal cation may be typically Fe ²⁺ , Co ²⁺ , Ni ²⁺ , and Cu ²⁺ .

In addition, the present invention features a biodegradable time-controlled mulching film prepared by extrusion molding the resin composition for the mulching film.

According to the present invention, by further including surface-modified biomass in addition to the biodegradable polymer resin, the price competitiveness of the mulching film can be secured, and the biodegradation time of the mulching film is appropriately adjusted in consideration of the crop growth period using an oxidation promoter. By controlling it properly, the application range can be expanded compared to the existing mulching film, and there is an effect of securing mechanical properties.

1 is an explanatory diagram showing a biodegradation process of a resin composition for a mulching film according to the present invention.

Hereinafter, the constituent elements and technical features of the present invention will be described in more detail through the following embodiments. However, the following examples are merely illustrative of the content of the present invention, and the scope of the invention is not limited by the examples.

First, explaining the principle that the mulching film according to the present invention can properly control the biodegradation time, energy is generated in the process of digesting and absorbing biomass powder by microorganisms, and the energy obtained by geothermal heat or external ultraviolet rays. As a result, the divalent cation of the transition metal used as an oxidation accelerator is activated and electrons occupied in the chain of the polyolefin-based polymer, which is a petroleum polymer, are removed, and the chain is broken, resulting in a low molecular weight. As a result, the molecular weight of the mulching film falls to 2,000 or less as it is hydrolyzed and reduced to a low molecular weight. This low molecular weight is biodegradable into monomers that can be digested and absorbed by microorganisms. Therefore, in order to control the physical properties of the mulching film so that it is not biodegraded for a certain period in consideration of the crop growth period, etc., it is possible to control the decomposition rate of the mulching film by adjusting the content of the oxidation accelerator involved in the oxidation promotion of the synthetic resin.

The present invention relates to a resin composition for a mulching film, based on 100 parts by weight of a biodegradable polymer resin, 10 to 35 parts by weight of a polyolefin-based resin, 15 to 25 parts by weight of a surface-modified biomass, the biodegradable polymer resin and the polyolefin-based 3 to 7 parts by weight of a compatibilizer for compatibility of the resin and 0.025 to 0.5 parts by weight of an oxidation accelerator for biodegradation rate control based on 100 parts by weight of the polyolefin-based

The biodegradable polymer resin is a component that provides biodegradability while securing a predetermined level of tensile strength and elongation to the mulching film, and is commonly used as an aliphatic polyester biodegradable resin, or an aliphatic/aromatic copolyester biodegradable resin. As long as it is used, the type is not greatly limited. Representative biodegradable polymer resins are polybutylene adipate terephthalide (PBAT), thermoplastic starch, polybutylene succinate (PBS), polybutylene adipate (PBA), and polybutylene succinate-adi Pate (PBSA), polybutylene succinate-terephthalate (PBST) rehydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), and may be one or more selected from the group consisting of polylactic acid (PLA), and , In consideration of the physical properties of the mulching film, it is preferable to include PBAT, and may further include thermoplastic starch or polylactic acid (PLA) to increase physical stability.

The polyolefin-based resin may be one or more selected from the group consisting of LDPE, HDPE, MDPE, LLDPE, VLDPE, PP, PVC, EVA, vinyl acetate, and copolymers thereof, and more preferably LDPE.

With respect to 100 parts by weight of the biodegradable polymer resin, it is preferable to include 10 to 35 parts by weight of the polyolefin resin.If it is included in less than 10 parts by weight of the lower limit, the effect of supplementing the weak physical properties of the biodegradable polymer may be reduced. In addition, it may not be possible to properly control the disintegration time because no visible effect can be obtained on the activity of the disintegration accelerator. On the contrary, when the content exceeds the upper limit of 35 parts by weight, the proportion of synthetic resin is increased, so that biodegradation is not smoothly performed, and thus a contaminant of microplastics may be left in the final decomposition product.

The surface-modified biomass may be obtained by hydrophobizing at least one of hydroxyl groups (-OH groups) of a cellulose unit with silane using a silane coupling agent. Cellulose, the main component of biomass, has a low compatibility with the hydrophobic polyolefin resin because the polar -OH groups present on the surface are hydrophilic, so dispersibility is poor. (Silane coupling agent; SCA) is used to hydrophobize. The silane coupling agent has a reactive group that reacts with an inorganic material and a functional group that reacts with an organic material, and because of this structural feature, chemical bonding between an organic material and an inorganic material is possible, so that the biomass is surface-treated with silane to obtain a reaction between the polyolefin-based resin. Cohesion can be improved. The surface-modified biomass may be herbaceous biomass including rice straw, barley straw, wheat straw, rice husk, corn stalks and leaves, soybean stalks, bean pods, onion stalks, sweet potato stalks, pine needles, or coffee grounds. Through this, there is an additional effect of improving biodegradability in the future while utilizing waste resources.

With respect to 100 parts by weight of the biodegradable polymer resin, it is preferable to include 15 to 25 parts by weight of the surface-modified biomass. If it is included in less than 15 parts by weight, it is difficult to control the biodegradation rate, and the biomass is a polyolefin-based resin. Since the polymer and the biodegradable polymer play a physical filling role, if the content is insufficient, the physical properties decrease and molding processability becomes a problem, and if it contains more than 25 parts by weight, the cooling rate may be accelerated to weaken the crystallinity of the resin.

In addition, the present invention includes a compatibilizer for compatibility with the biodegradable polymer resin and the polyolefin resin. The compatibilizer may be at least one selected from the group consisting of inorganic fillers, glycidyl methacrylate, ethylene vinyl alcohol (EVA), polyvinyl alcohol (PVA), ethylene vinyl acetate, SEBS, maleic anhydride and MAP resin, In particular, the inorganic filler may be one or more nano-sized powders selected from the group consisting of calcium carbonate, glass fiber, talc, mica, silica stone, clay powder, wollastonite, talc, kaolin powder, silica, mica, kaolin, and titanium dioxide. have.

With respect to 100 parts by weight of the biodegradable polymer resin, it is preferable to include 3 to 7 parts by weight of the compatibilizer. If it is included in less than 3 parts by weight, the aggregation of biomass may occur, and the biodegradable polymer resin and the olefin-based Due to the lack of filling between the resins, a phase separation phenomenon between polymers may occur, which can ultimately degrade physical properties. On the contrary, if it contains more than 7 parts by weight, the viscosity of the blended synthesis result is lowered beyond the filling range of the biodegradable polymer and olefin-based polymer, so that it is lower than the melt index of the final mulching film molding, thus weakening the pullability of the mulching film. In addition, as the friction coefficient increases, thermal decomposition is induced, resulting in a lower molecular weight of the resulting mulching film, which may adversely affect physical properties.

In addition, the present invention includes an oxidation accelerator for controlling the rate of biodegradation. When an oxidation accelerator is added to a polyolefin-based resin compound such as polyethylene or polypropylene that is single bond stabilized, the oxidation accelerator is activated by an external energy source, and oxidation is controlled according to the following mechanism.

Eventually, the molecular weight of the polyolefin-based polymer gradually decreases as the decomposition reaction proceeds step by step as described in the reaction equation described above, and oxides (Carbonyl & Carboxyl groups) are generated according to the above reaction, and are decomposed into water and carbon dioxide as shown in FIG. .

The oxidation accelerator is preferably contained in an amount of 0.025 to 0.5 parts by weight based on 100 parts by weight of a polyolefin resin.If it is included in an amount of less than 0.025 parts by weight, the effect of decomposing the polyolefin resin may be reduced and the decomposition induction time may be longer than expected. If it contains more than 0.5 parts by weight, the melt index (MI) of the compound may increase due to the low molecular weight of the polyolefin resin during the mixing and blending process, resulting in poor film forming workability. It can have a decomposition time similar to that of the existing biodegradable polymer resin alone.

Accordingly, the decomposition rate of the mulching film is determined according to the amount of the decomposition accelerator added according to the content of the polyolefin resin, and the physical properties of the mulching film may be determined by the ratio of the oxidation accelerator and the polyolefin resin.

On the other hand, considering that the resin composition for a mulching film according to the present invention is used as a master batch when manufacturing a biodegradable mulching film, it is preferably in a pellet form. The composition for a pellet-type mulching film can be prepared by mixing and melting components constituting the same, and then extruding through a twin-screw extruder to pellet the extrudate.

At this time, in order to control the biodegradation time more efficiently, a primary compound is prepared by mixing and blending an appropriate amount of an oxidation accelerator into the polyolefin resin in consideration of the decomposition time, and then biodegradable polymer resin, surface-modified biomass powder, compatibilizer, etc. It is preferable to prepare a secondary compound by further mixing and blending. If the entire composition is mixed and compounded to produce a mulching film, the oxidation accelerator may affect the binding chain of the biodegradable polymer and accelerate the decomposition rate, so that the biodegradation time may not be properly controlled.

Hereinafter, it will be confirmed that the biodegradation time of the mulching film according to the present invention can be appropriately controlled through the examples according to the present invention.

Hereinafter, it will be confirmed that the biodegradation time of the mulching film according to the present invention can be appropriately controlled through the examples according to the present invention.

[Production Example 1]

In order to check the decomposition rate of the olefin-based resin according to the amount of the oxidative decomposition accelerating catalyst input, a master batch for an olefin-based resin oxidation decomposition experiment having a composition ratio shown in Table 1 was prepared.

(Unit: wt%) division Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Example 4 Manufacturing Example 5 LLDPE 3126
(Lotte Chemical) 99.475 99.4 99.1 99.0 100 Oxidation accelerator Fe ²⁺
(Dupont) 0.025 0.1 0.4 0.5 - Flow Oil
(Korean oil painting) 0.5 0.5 0.5 0.5 system 100 100 100 100 100

[Experimental Example 1]

A mulching film having a thickness of 20 μm was prepared using a master batch for oxidation decomposition experiments of olefin resins having a composition ratio of Table 1 (Production Examples 1 to 4), and exposure time of ultraviolet rays (using a wavelength of 280 to 340 nm ultraviolet B lamp) The results of the change in physical properties for each film are summarized in Tables 2 and 3.

<Tensile strength measurement value> (Unit: Mpa) Revelation time Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Example 4 Manufacturing Example 5 0 hours 34.72 34.45 36.35 35.72 35.79 50 hours 33.35 32.73 30.53 29.32 34.10 100 hours 30.75 17.32 23.84 20.72 31.03 200 hours 26.73 14.76 7.92 4.82 28.32

<Elongation rate change value> (Unit:%) Revelation time Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Example 4 Manufacturing Example 5 0 hours 232 246 203 243 224 50 hours 205 215 195 187 184 100 hours 175 123 115 132 150 200 hours 113 108 43 15 120

When a mulching film was prepared by adding an oxidation accelerator to the olefinic resin as in Preparation Examples 1 to 4, it was confirmed that the oxidation promoter was activated by ultraviolet rays, and the olefinic resin was oxidized, causing a biodegradation process to gradually decrease physical properties. there was. On the other hand, it was confirmed that when the oxidation accelerator was not included, the decrease in physical properties was relatively weak.

[Experimental Example 2]

In order to confirm the degree of biodegradation time control in the case corresponding to the composition ratio according to the present invention (Experimental Examples 1 to 3) and the case made mainly of biodegradable polymer resin (Comparative Example), an olefin-based resin composed of the composition ratio shown in Table 4 below. A biodegradation time-controlled mulching film (Experimental Examples 1 to 3, Comparative Example) having a thickness of 20 μm was prepared using a master batch for oxidative decomposition experiments, and each film according to the exposure time of ultraviolet rays (with a wavelength of 280 to 340 nm ultraviolet B lamp) The results of the change in physical properties are summarized in Tables 5 and 6.

<Biodegradation time control material composition> (Unit: wt%) division Experimental Example 1 Experimental Example 2 Experimental Example 3 Comparative example Remark LLDPE+
Oxidation accelerator Manufacturing Example 1 15 250 ppm Manufacturing Example 2 15 1,000 ppm Manufacturing Example 4 15 5,000 ppm PBAT 56 56 56 67 Biodegradable polymer CaCO ₃ 4 4 4 30 Commercial filler 2㎛ Surface modified rice husk powder 20 20 20 Silane 1% treatment particle diameter 7㎛ SEBS 2 2 2 Compatibilizer PE-wax 2 2 2 2 Dispersant Zn-st One One One One Slip agent system 100 100 100 100

<Tensile strength measurement value> (Unit: Mpa) Revelation time Experimental Example 1 Experimental Example 2 Experimental Example 3 Comparative example 0 hours 20.5 21.8 20.3 14.7 50 hours 18.3 16.9 15.5 12.5 100 hours 14.6 13.8 10.2 10.3 200 hours 12.7 9.7 7.6 5.03

<Elongation rate change value> (Unit:%) Revelation time Experimental Example 1 Experimental Example 2 Experimental Example 3 Comparative example 0 hours 116 128 125 119 50 hours 78 92 87 75 100 hours 37 65 52 43 200 hours 11 37 28 17

In the case of Experimental Examples 1 to 3 corresponding to the composition ratio according to the present invention, it was confirmed that the biodegradation time can be quickly or slowly controlled according to the ratio of LLDPE and the oxidation promoter.

Claims (9)

Mixing, melting, and extruding low-density polyethylene (LDPE) and an oxidation accelerator at a weight ratio of 100:0.025 to 0.5 to prepare a first pellet; And
100 parts by weight of a biodegradable polymer resin; And 15 to 25 parts by weight of surface-modified biomass; And mixing, melting and extruding 10 to 35 parts by weight of the first pellet to prepare a second pellet.
Resin pellet manufacturing method for a mulching film comprising a. The method of claim 1,
The biodegradable polymer resin is polybutylene adipate terephthalide (PBAT), thermoplastic starch (thermo plastic starch), polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate-adi Pate (PBSA), polybutylene succinate-terephthalate (PBST) rehydroxybutyrate-valerate (PHBV), polycaprolactone (PCL), polylactic acid (PLA), characterized in that at least one selected from the group consisting of Method for producing resin pellets for mulching films. delete The method of claim 1,
The surface-modified biomass is a method for producing a resin pellet for a mulching film, characterized in that at least one of hydroxyl groups (-OH groups) of a cellulose unit is hydrophobized with silane using a silane coupling agent. The method of claim 1,
The surface-modified biomass is for mulching film, characterized in that it is a herbaceous biomass containing rice straw, barley straw, wheat straw, rice husk, cornstalks and leaves, soybean stems, bean pods, onion stems, sweet potato stems, pine needles or coffee grounds Resin pellet manufacturing method. The method of claim 1,
When preparing the secondary pellet, mixing, melting and extruding, further including 3 to 7 parts by weight of a compatibilizer,
The compatibilizer is characterized in that at least one selected from the group consisting of inorganic fillers, glycidyl methacrylate, ethylene vinyl alcohol (EVA), polyvinyl alcohol (PVA), ethylene vinyl acetate, SEBS, maleic anhydride and MAP resin. Method for producing a resin pellet for a mulching film. The method of claim 6,
The inorganic filler is at least one nano-sized powder selected from the group consisting of calcium carbonate, glass fiber, talc, mica, silica stone, clay powder, wollastonite, talc, kaolin powder, silica, mica, kaolin, and titanium dioxide. Method for producing resin pellets for mulching films. The method of claim 1,
The oxidation accelerator is a method for producing a resin pellet for a mulching film, characterized in that the compound containing a divalent transition metal cation. A biodegradable mulching film prepared using a pellet prepared by the method according to any one of claims 1, 2 and 4 to 8.

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