KR101020275B1 - Degradable film and method of the same - Google Patents

Abstract

PURPOSE: A method for preparing a naturally degradable film is provided to prepare a naturally degradable film with excellent natural degradability, initial elongation, and tensile strength. CONSTITUTION: A method for preparing a naturally degradable film comprises the steps of: pulverizing rice hulls; drying the pulverized husk powder; injecting wax into the dried husk powder, mixing the added mixture at a high speed to coat the surface with wax; injecting additives into the husk powder coated with wax, wherein the additives are starch, starch plasticizer, oxidizing agent, lubricant, organic acid, binder resin, and inorganic filler; extruding the mixture to prepare pellets; and adding the pellets to a plastic resin and extruding the mixture in a film shape.

Description

Degradable film and method of the same

The present invention relates to a naturally decomposed film and a method for producing the same.

With the increase in the use of various plastic products including films, the amount of plastic waste has increased exponentially in recent years. Plastic waste is generally disposed of by landfill, incineration or recycling.

However, in the case of landfill, the decomposition time of the landfilled plastic waste takes a very long time, which causes a shortage of landfill space and soil pollution. Incineration also contributes to global warming as well as air pollution due to the generation of toxic gases. In addition, recycling is not only difficult to collect and separate, but also increases the processing cost.

In recent years, plastic products have been developed to provide fast degradability. For example, there has been disclosed a disposable plastic container manufactured using a composition in which starch is added together with rice straw, rice hull, and sawdust grind to a synthetic resin. However, in the case of such a composition is effective in improving the degradability, when produced in the form of a film has a disadvantage in physical properties, in particular the initial elongation and tensile strength of the film produced.

Accordingly, an object of the present invention is to provide a method for producing a naturally-decomposable film having excellent natural decomposition rate as well as excellent physical properties such as initial elongation and tensile strength.

In another aspect, the present invention is to provide a natural decomposition film having excellent natural decomposition rate as produced by the above production method.

In order to achieve the above object, the present invention is a crushing step of grinding chaff into 80 ~ 400 mesh; Drying the crushed rice hull powder at 90-250 ° C. for 5 to 60 minutes so that the moisture content is 10% or less; A coating step of coating wax on the surface of the rice husk powder by adding wax to the dried rice husk powder at high speed by stirring at 300 to 800 rpm; A mixing step of adding starch, starch plasticizer, oxidizing agent, lubricant, organic acid, binder resin, and inorganic filler to the wax-coated rice husk powder as an additive; Pellet production step of producing a pellet by extruding the mixed mixture; And a film manufacturing step of adding the prepared pellets to the plastic resin and extruding it into a film form.
5 to 70 parts by weight of chaff, 0.5 to 5 parts by weight of wax, 5 to 50 parts by weight of starch, 0.2 to 6 parts by weight of oxidant, 0.5 to 5 parts by weight of lubricant, 0.2 to 5 parts by weight of organic acid, binder 15 to 50 parts by weight of resin and 5 to 65 parts by weight of inorganic filler are added, the starch plasticizer is added to 10 to 30 parts by weight based on 100 parts by weight of starch, and the pellet is 10 to 200 parts by weight based on 100 parts by weight of plastic resin. It provides a method for producing a naturally decomposed film, characterized in that the addition.

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The plastic resin may be at least one selected from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), and polypropylene (PP).

In another aspect, the present invention provides a naturally decomposed film, characterized in that produced by the above production method.

Naturally decomposed film prepared according to the present invention is not only excellent in the natural degradability of the film produced as a chaff as a main body, but also has a useful effect of exhibiting excellent properties such as initial elongation and tensile strength.

1 is a graph showing the tensile strength measurement results according to Experimental Example 1.
2 is a graph showing the measurement results of the elongation rate according to Experimental Example 1. FIG.

Hereinafter, the present invention will be described in detail.

Referring to the naturally-decomposed film according to the present invention and a manufacturing method thereof in detail.

The biodegradable film according to the present invention is a grinding step of crushing chaff, a drying step of drying the crushed chaff, a coating step of coating a wax, a mixing step of adding and mixing additives, a pellet manufacturing step of pelletizing the mixture and The prepared pellet is added to a plastic resin and then manufactured through a film manufacturing step of extruding the film into a film.

The grinding step is to crush the chaff into 80 ~ 400 mesh.

If the grain size of the crushed rice husk is less than 80 mesh, the grain size of the rice husk is large, so that the surface becomes rough when applied to the production of the film, which lowers the quality and the initial tensile strength of the film. If it exceeds, there is a disadvantage in that a lot of time is required for grinding to lower the overall productivity. Therefore, the grain size of the chaff is preferably 80 to 400 mesh. The chaff may be ground using a conventional mill.

The chaff may be included from 5 to 70 parts by weight based on 100 parts by weight of the pellets obtained in the pellet manufacturing step. When the content of the chaff is less than 5 parts by weight based on the above standards, the degradation of the naturally decomposed film, there is a disadvantage that the quality of the product is lowered when it exceeds 70 parts by weight.

The drying step is to dry the crushed chaff powder for 5 to 60 minutes at 90 ~ 250 ℃ so that the moisture content is less than 10%.

Here, the drying temperature and drying time are those that can be appropriately adjusted as necessary, but do not necessarily limit the numerical value, it is preferable to dry for 5 to 60 minutes at 90 ~ 250 ℃ to facilitate the moisture content control. Do. At this time, the moisture content of the ground chaff powder is less than 10% in order to facilitate handling and wax coating.

The coating step is a step in which the wax is coated on the surface of the rice husk powder by adding a wax to the dried rice husk powder at high speed stirring at 300 ~ 800rpm.

The coating of the wax on the surface of the rice husk powder is intended to prevent the reabsorption of moisture on the surface of the rice husk.

Generally known waxes can be used without limitation. For example, the waxes that can be used include paraffin wax, liquid paraffin wax, beeswax, mold wax, emulsion wax, candelilla wax, PE wax or PP wax and the like, each of which can be used alone or in combination of two or more. Can be used.

At this time, it is preferable to add 0.5-5 weight part of wax with respect to 100 weight part of pellets. If the amount of wax is more than 5 parts by weight based on the above criteria, there is a disadvantage in reducing the productivity by forming residue in the production equipment during film manufacturing, and if less than 0.5 parts by weight, the wax is not coated on the surface of the chaff reabsorbed moisture There are disadvantages such as being.

In the coating step, after the wax is added, high speed stirring is performed at 300 to 800 rpm. When the high speed stirring is performed, the wax is naturally melted by self-heating due to the high speed stirring, and the surface of the rice husk powder is coated.

The mixing step is a step of mixing by adding at least one additive selected from the group consisting of starch, starch plasticizer, oxidizing agent, lubricant, organic acid, binder resin and inorganic filler to the wax-coated chaff powder.

The additives serve to assist the decomposition of the film. Preferably, the additives include all of starch, starch plasticizer, oxidizing agent, lubricant, organic acid, binder resin, and inorganic filler.

The starch and starch plasticizer is to improve the moldability of the film. The starch may specifically illustrate corn starch, and may be added to include 5 to 50 parts by weight based on 100 parts by weight of the pellet. The starch plasticizer may specifically include glycerin and sorbitol, and may be added to include 10 to 30 parts by weight based on 100 parts by weight of the starch based on the starch content. If the content of the starch and starch plasticizer is included in the above range on the basis of the above standards, it is preferable to add the film within the above range because the quality improvement and good moldability of the film can be obtained.

The starch and starch plasticizer is preferably mixed before the addition and then added after heat treatment at a high temperature of 100 ℃ or more. As such, when the heat treatment is performed, the starch is changed in properties, thereby improving moldability in manufacturing the film.

The oxidizing agent promotes the oxidative decomposition function of the plastic resin and serves to improve the degradability of the natural decomposition film produced.

The oxidizing agent may be used without limitation as long as it is known as an oxidizing agent of a plastic resin, and specific examples thereof include oleic acid, linoleic acid, linolenic acid, arachidonic acid, and palmitoleic acid.

The oxidant may be added to include 0.2 to 6 parts by weight based on 100 parts by weight of the pellet. When the content of the oxidizing agent is less than 0.2 parts by weight based on the above standard, it is not possible to improve the oxidative decomposition function of the plastic resin, and when it is more than 6 parts by weight, the disadvantage of lowering productivity by forming wastes in the production equipment during film production. have.

The glidants aid in good flow and help the pellets to be produced smoothly. As the glidants, generally known ones may be used without limitation, and specifically, zinc stearate may be exemplified.

The lubricant may be added to include 0.5 to 5 parts by weight based on 100 parts by weight of the pellet. When the content of the lubricant is less than 0.5 parts by weight based on the above standard, the flow-improving effect is low, and when more than 5 parts by weight, there is a disadvantage in reducing the productivity by forming a residue in the production equipment during film production.

The organic acid promotes oxidation and serves to help degradability. The organic acid is not necessarily limited, but may include at least one selected from the group consisting of citric acid, malic acid, malic acid, and acetic acid.

It is preferable to add 0.2-5 weight part of said organic acids with respect to 100 weight part of pellets. If the organic acid exceeds 5 parts by weight based on the above standard, there is a disadvantage in that the manufacturing cost of the film is increased, and when added below 0.2 parts by weight, the effect is insignificant.

The binder resin is to form a pellet by combining the powdered raw material, at least one selected from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE) and polypropylene (PP) Can be used.

The binder resin is preferably added in an amount of 10 to 60 parts by weight based on 100 parts by weight of the pellets. When the content of the binder resin exceeds 60 parts by weight based on the above standards, the pellet is formed well, but there is a disadvantage of causing an increase in manufacturing cost and a degradability of natural decomposition, and when the content is less than 10 parts by weight, the pellet is broken due to insufficient binding force. There is this.

As the inorganic filler serves to promote decomposition, at least one selected from the group consisting of calcium carbonate, clay and loess may be used.

The content of the inorganic filler is preferably added 5 to 65 parts by weight based on 100 parts by weight of the pellets. When the content of the inorganic filler exceeds 65 parts by weight based on the above standard, there is a disadvantage in that the physical properties such as the initial tensile strength and elongation of the produced natural decomposition film, there is a disadvantage, when less than 5 parts by weight to obtain excellent natural degradability There is a problem that is difficult.

The pellet manufacturing step is a step of producing a pellet by extruding the mixture mixed in the mixing step.

Pelletization can be easily performed using a conventional extruder, and the size can also be suitably adjusted as needed.

The film manufacturing step is a step of extruding into a film form after adding the prepared pellets to the plastic resin. When extruded in the form of a film as described above, a naturally decomposed film according to the present invention is obtained, and the naturally decomposed film thus obtained has excellent natural degradability.

The plastic resin may be used without limitation as long as it is used in film production, for example, at least one selected from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), and polypropylene (PP). You can use one.

The blending ratio of the pellet and the plastic resin is not particularly limited, but preferably the pellet may be added in an amount of 10 to 200 parts by weight based on 100 parts by weight of the plastic resin. When the amount of the pellet added is less than 10 parts by weight based on the above standards, there is a disadvantage in that the decomposability of the produced naturally decomposed film is lowered. There is a problem of poor physical properties.

The pellet and the plastic resin are blended in a film extruder including a conventional hopper, and the pellets and the plastic resin are added to the hopper, and then extruded into a film form through a die while melting and stirring, thereby easily dissolving the biodegradable film according to the present invention. You can get it. In this case, in order to impart color to the naturally decomposed film to be prepared, the hopper may be extruded after adding dyes or pigments or master batches containing the same together, and the content may be appropriately adjusted according to the desired color implementation. .

Naturally decomposed film according to the present invention prepared in this way contains a large amount of natural ingredients that can help the chaff and decomposition rate, the decomposition rate is very excellent, especially physical properties or excellent properties such as the initial elongation and tensile strength of the film produced Indicates. The naturally decomposed film thus prepared may be used as an industrial film packaging material, a plastic bag or a food packaging material.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are presented to aid the understanding of the present invention, but the present invention is not limited thereto.

≪ Example 1 >

The chaff powder pulverized to have a particle size of 80 ~ 400 mesh was dried for 30 minutes at 100 ± 10 ℃ to obtain a dried chaff powder having a water content of 9.7%. 0.19 Kg of wax was added to 2.41 Kg of the dried chaff powder, and the mixture was stirred at 500 rpm at a high speed so that the wax was coated on the surface of the rice husk powder. 0.18 Kg, 2.2 Kg of LLDPE and 2.31 Kg of inorganic filler were added, mixed, put into a hopper, and then extruded in an extruder to prepare pellets.

In a state where the hopper temperature of the film extruder was raised to 200 ° C., 6.5 Kg of LDPE and 0.5 Kg of LLDPE per 3 Kg of the pellets obtained above were added together, followed by extrusion with a die while melt mixing to prepare a film having a thickness of 50 μm.

<Example 2>

In the same manner as in Example 1, except that the film was extruded into a die while melt-mixing 7.5 kg of LDPE and 0.5 kg of LLDPE per 2 kg of pellets while the hopper temperature of the film extruder was raised to 200 ° C. It was.

<Example 3>

In the same manner as in Example 1, except that the film was extruded into a die while melting and mixing 6.5 Kg of HDPE and 0.5 Kg of LLDPE per 3 Kg of pellets while the hopper temperature of the film extruder was raised to 200 ° C. Was carried out.

<Example 4>

In the same manner as in Example 1, except that the film was extruded into a die while melt-mixing the HDPE 7.5Kg and LLDPE 0.5Kg per 2Kg pellets while the hopper temperature of the film extruder was raised to 200 ℃ Was carried out.

Experimental Example 1

Tensile strength and elongation were measured using a UTM (Universal Testing Machine, Daekyung Tech, Korea) device for each film cut to 25 × 100mm according to ASTM D 3826 method using the film prepared in the above Example.

In this case, in order to evaluate the UV degradability together, each film was exposed to a UV wavelength of 352nm at 58 ° C. for 24 hours to 240 hours (10 cm distance between the UV lamp and the film), and then tensile strength and elongation were measured.

As a control (control) was used to prepare a film of LDPE alone, the tensile strength and elongation according to the UV wavelength exposure time was measured.

The measured tensile strength and elongation rate are shown in Table 1 (tensile strength), Table 2 (elongation rate), FIGS. 1 and 2.

Tensile Strength (Mpa) UV irradiation time Control (LDPE) Example 1 Example 2 Example 3 Example 4 0 16.9 15.18 16.44 13.72 16.98 24 16.71 19.585 15.778 19.009 17.181 48 16.901 19.675 13.737 18.273 16.039 72 16.732 11.905 13.967 16.292 15.644 96 16.708 11.168 14.092 12.951 13.714 120 16.333 10.71 10.381 13.533 11.836 144 14.136 9.916 9.721 10.734 10.52 168 14.275 9.316 9.361 9.956 9.448 192 14.407 9.063 9.64 11.41 8.571 216 14.909 10.543 10.832 10.377 7.731 240 14.587 9.468 9.603 13.089 7.981

As shown in Table 1, in the case of the tensile strength, the LDPE film used as a control and the films of Examples 1 to 4 according to the present invention can be seen that all have similar tensile strength before UV irradiation. Therefore, it can be seen that the films of Examples 1 to 4 prepared according to the present invention have excellent initial tensile strength.

On the other hand, in the case of the control, the change rate according to the UV irradiation was hardly observed, it can be seen that the film produced in the example shows a trend that the tensile strength sharply decreases after 48 hours of UV irradiation. This decrease in tensile strength is due to decomposition of the film. Therefore, the film produced according to the present invention can be confirmed not only excellent initial tensile strength but also very excellent degradability.

Elongation (%) UV irradiation time Control (LDPE) Example 1 Example 2 Example 3 Example 4 0 300 300 300 300 300 24 300 300 300 300 300 48 300 300 300 300 300 72 300 129.547 286.643 300 247.762 96 300 59.664 277.637 300 167.588 120 300 41.845 127.268 268.268 46.13 144 194.665 19.241 33.664 144.385 21.463 168 186.053 9.38 40.658 94.06 7.574 192 209.595 9.227 18.789 113.101 4.629 216 237.144 6.06 10.733 85.393 2.893 240 237.095 13.081 27.914 201.338 7.817

As shown in Table 2, in the case of the elongation rate, the LDPE film used as a control and the films of Examples 1 to 4 prepared according to the present invention showed the same elongation rate before UV irradiation. Therefore, it can be seen that the film produced according to the present invention has excellent initial elongation.

On the other hand, in the case of the control it can be seen that the change rate according to the UV irradiation shows a sharp change rate after 144 hours, the film prepared in the example can be seen that shows a trend that changes after 72 hours UV irradiation. This decrease in elongation is due to decomposition of the film. Therefore, the film prepared according to the present invention can be confirmed that not only the initial elongation is excellent, but also the decomposition is very excellent.

Experimental Example 2

In order to evaluate the thermal degradability of the film prepared in the above example, the specimen was cut into 13 ㅧ 90mm size and placed in a constant temperature and humidity chamber at 68 ㅁ 2 ° C relative humidity 85%, and preserved for 49 days, and the specimens were taken at intervals of 7 days. Tensile strength and elongation were measured using a UTM (Universal Testing Machine, Daekyung Tech, Korea) instrument.

As a control, a film made of LDPE alone was used, and tensile strength and elongation were measured.

The measured tensile strength and elongation are shown in Table 3 (tensile strength) and Table 4 (elongation).

Tensile Strength (Mpa) Days of heat treatment Control (LDPE) Example 1 Example 2 Example 3 Example 4 0 16.8 15.29 16.43 13.83 16.89 7 16.72 17.67 15.87 15.03 16.23 14 16.70 19.675 16.01 15.51 1.05 21 16.32 10.91 12.06 12.24 12.89 28 16.06 9.01 10.09 10.91 11.72 65 15.78 7.54 8.04 9.01 9.83 42 15.77 6.14 6.89 7.25 7.52 49 15.51 4.28 5.31 5.38 6.27

As shown in Table 3, in the case of the tensile strength, the LDPE film used as a control and the films of Examples 1 to 4 prepared according to the present invention had similar tensile strengths before heat treatment. Therefore, it can be seen that the films of Examples 1 to 4 prepared according to the present invention have excellent initial tensile strength.

On the other hand, in the case of the control, the change rate according to the number of days of heat treatment was hardly observed, but it can be seen that the film produced in the example shows a tendency to decrease the tensile strength sharply after 21 days of heat treatment. This decrease in tensile strength is due to decomposition of the film. Therefore, the film produced according to the present invention can be confirmed not only excellent initial tensile strength but also very excellent degradability.

Elongation (%) Days of heat treatment Control (LDPE) Example 1 Example 2 Example 3 Example 4 0 300 300 300 300 300 7 300 278 288 298 298 14 300 237 256 241 260 21 300 100 113 109 110 28 291 70 78 74 76 65 288 38 42 43 46 42 287 16 16 21 24 49 281 8 9 10 14

As shown in Table 4, in the case of the elongation rate, the LDPE film used as a control and the films of Examples 1 to 4 according to the present invention showed the same elongation rate before heat treatment. Therefore, it can be seen that the film produced according to the present invention has excellent initial elongation.

On the other hand, in the case of the control it can be seen that the rate of change according to the number of days of heat treatment is almost insignificant, but the film produced in the example shows a trend that changes after 14 days of heat treatment. This decrease in elongation is due to decomposition of the film. Therefore, the film prepared according to the present invention can be confirmed that not only the initial elongation is excellent, but also the decomposition is very excellent.

Experimental Example 3

Evaluation of biodegradability by mold of the film prepared in the above example was tested according to ASTM G21 method. That is, after cutting the sample to a certain size, the solid agar medium without a carbon source is used as a medium, and Aspergillus niger , Penicillium piniphilum , and chattomium globo are commonly found in soil. A 10-day interval to assess the extent of mold cover on a 60-day sample by aseptically spraying a mixed mycelium suspension of islands (Chaetomium globosum), Gliocladium virens, and Aureobasidium pullulans . Biodegradability was measured.

In addition, the biodegradability evaluation by bacteria was tested according to the ASTM G22 method. Cell-suspension suspensions of Pseudomonas aeruginosa and Baccllus subtillus were applied to the sample in a sterile state on a solid agar medium without a carbon source. It evaluated by the following method.

As a control, a film produced from LDPE alone was used.

-Biodegradability evaluation

Class 0: no growth in observed samples

Level 1: Growth less than 10% in observed samples

Level 2: Growth is more than 10% and less than 30% in observed samples (slight growth)

Level 3: Growth is more than 30% and less than 60% in the observed sample (medium growth)

Level 4: Growth is more than 60% in observed samples (dense growth)

At the same time, the sample is taken out every 20 days while being kept in a constant temperature and humidity chamber fixed at a relative humidity of 85% and an internal temperature of 30 ° C at the same time, and the weight loss degree of the sample according to the degree of growth of the mold is measured as a ratio. It was.

At this time, the weight loss rate was measured based on the following equation (1).

&Quot; (1) &quot;

Weight loss rate (%) = weight after sampling / weight of original sample ㅧ 100

In the case of bacteria, the relative humidity was fixed at 85% and the internal temperature of 37 ° C., and the weight loss was measured in the same manner as described above.

Experimental results of the degree of biodegradability and weight loss by the fungus are shown in Table 5, and the results of biodegradability and weight loss by the bacteria are shown in Table 6 below.

Evaluation of biodegradation by mold and weight loss test results division Biodegradable Weight loss rate (%) 10 days 20 days 30 days 40 days 50 days 60 days 20 days 40 days 60 days Control (LDPE) 0 0 0 0 0 0 99.9 99.9 99.9 Example 1 One 2 3 3 4 4 94.1 71.1 53.1 Example 2 One 2 2 3 3 4 95.4 83.7 61.6 Example 3 One 2 3 3 4 4 94.7 72.4 54.5 Example 4 One 2 2 3 3 4 95.9 85.2 63.2

Evaluation of the degree of biodegradation by bacteria and weight loss test results division Biodegradable Weight loss rate (%) 10 days 20 days 30 days 40 days 50 days 60 days 20 days 40 days 60 days Control (LDPE) 0 0 0 0 0 0 99.9 99.9 99.9 Example 1 One 2 3 3 4 4 95.1 72.2 55.6 Example 2 One 2 2 3 3 4 95.7 84.5 62.2 Example 3 One 2 3 3 4 4 95.2 73.4 55.1 Example 4 One 2 2 3 3 4 96.3 84.2 64.7

As can be seen from Tables 5 and 6, it can be seen that the films of Examples 1 to 4 prepared according to the present invention show superior biodegradability compared to LDPE films used as controls. Accordingly, it can be seen that the weight decreases rapidly with time. Therefore, it can be seen that the film produced according to the present invention is excellent in degradability.

Claims (8)

Grinding chaff crushed into 80 ~ 400 mesh;
Drying the crushed rice hull powder at 90-250 ° C. for 5 to 60 minutes so that the moisture content is 10% or less;
A coating step of coating wax on the surface of the rice husk powder by adding wax to the dried rice husk powder at high speed by stirring at 300 to 800 rpm;
A mixing step of adding starch, starch plasticizer, oxidizing agent, lubricant, organic acid, binder resin, and inorganic filler to the wax-coated rice husk powder as an additive;
Pellet production step of producing a pellet by extruding the mixed mixture; And
It comprises a film manufacturing step of extruding into a film form after adding the prepared pellets to the plastic resin,
5 to 70 parts by weight of chaff, 0.5 to 5 parts by weight of wax, 5 to 50 parts by weight of starch, 0.2 to 6 parts by weight of oxidant, 0.5 to 5 parts by weight of lubricant, 0.2 to 5 parts by weight of organic acid, binder 15 to 50 parts by weight of resin and 5 to 65 parts by weight of inorganic filler are added, and the starch plasticizer is added to 10 to 30 parts by weight based on 100 parts by weight of starch,
The pellet is 10 to 200 parts by weight based on 100 parts by weight of the plastic resin, characterized in that for producing a natural decomposition film.
delete delete delete delete delete The method according to claim 1,
The plastic resin is at least one selected from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP).
Naturally decomposed film produced by the manufacturing method of claim 1 or 7.

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