KR950013176B1 - Concentrated masterbatch of biodegradable high density polyethylene filled by starch - Google Patents

Abstract

The master batch consists of 100 parts matrix resin, 25-80 parts biodegradable filler, 5-25 parts autooxidizing agent, 1-20 parts plasticizer, 3-20 parts surfactant, and stabilizer. The matrix resin is a mixture of high density polyethylene, low density polyethylene and linear low density polyethylene with a mixing ratio of 95-5 : 305 : 20-5. The biodegradable filler is chosen from starch, acid-treated starch, oxidized starch, ester starch, ether starch or their mixture. The autooxidizing agent is chosen from unsaturated fatty acid like oleic acid, fatty acid ester like ethyl oleate, corn oil, or their mixture. The plasticizer is selected from oleamide, stearamide, polyethylene wax, paraffin wax, or their mixture.

Description

Manufacturing method of concentrated masterbatch of starch filled biodegradable high density polyethylene

The present invention is a method for producing a concentrated masterbatch of starch-filled biodegradable high density polyethylene which is biodegradable by adding natural polymer starch and various modified starches, and an automatic oxidant capable of accelerating biodegradation to high density polyethylene used as a general purpose plastic. It is about.

In general, plastics are used for various purposes in various fields of society because of their excellent functionality and stability, and their usage is increasing every year.

On the other hand, waste plastics in proportion to them have been the main culprit of harming the natural environment as they are left in landfills for a long time in an uncorrupted or stable state.

Accordingly, various waste plastic treatment methods are being introduced in the United States, Europe, and Japan, and other countries around the world, and special attention is being paid to the development of degradable plastics that decay by the plastic itself.

Such degradable plastics can be classified into photo degradable plastics and bio degradable plastics. The photo degradable plastics can be easily controlled and have a fast decomposition rate, but are not decomposed in the ground. It has disadvantages and has many problems in use.

Biodegradable plastics can be decomposed in the presence of microorganisms such as in the ground or in water. Starch-filled biodegradable plastics are considered to have the most potential for generalization. Among them, US Patent No. 4,021,388 describes pure water. Biodegradable films filled with pure starch in low-density polyethylene have been described, but the physical properties of the films are not solved as the starch is filled.

In addition, U.S. Patent No. 4,133,784 studied the method for producing the film with the addition of the low fraction of the ethylene-acrylic acid copolymer, but the ethylene-acrylic acid copolymer used is not universal and expensive, and mass production is not easy. It is almost impossible and the physical properties of the produced film are extremely weak for practical use.

Meanwhile, Republic of Korea Patent No. 38710 relates to low density polyylene, and Republic of Korea Patent No. 48630 relates to a starch-filled biodegradable film and a method of manufacturing the same using a mixture of polyethylene-ethylene vinyl acetate. Although it is very necessary to use a master batch filled with a matrix resin with high concentration of starch in the actual film manufacturing process, there is no invention regarding a highly concentrated master batch.

The production of biodegradable films using highly concentrated masterbatches has significant advantages in improving processability and reducing processing costs.

In particular, the use of high-density polyethylene as the matrix hand in the present invention is because it can improve the weak physical properties with the biodegradable film developed so far and impart improved biodegradability.

In general, it is known that biodegradability is better in the case of linear polymers having less branches than those having more branches in the molecular structure. Low-density polyethylene has a more branched structure, while high-density ethylene is linear. As it has a molecular structure of polymer, it is more biodegradable and excellent in physical properties.

Since such high density polyethylene is generally manufactured and sold as ultrathin film, it is recognized that it is very difficult to mold into a film when a general filler is added. In the present invention, low density polyethylene and linear low density polyethylene are used for the purpose of improving film processability. It was confirmed that the above problems can be solved by selectively adjusting the amount of (Linear Low Density Polyethylene).

The use ratio of high density polyethylene: low density polyethylene: linear low density polyethylene in a concentrated masterbatch is 95 to 50: 30 to 5: 20 to 5, and the ratio of 95 to 5: 5 to 0: 5 to 0 is used for film production. Adjust the mixing ratio of the resin.

The amount of these mixed resins is 100 parts by weight.

As biodegradable fillers, corn starch, rice starch, potato starch, tapioca starch, wheat starch, sweet potato starch, etc. can be used, but corn starch is most suitable considering the particle size and economical aspect of starch.

Concentrated masterbatch of the present invention can be filled with starch up to 25 to 80 parts by weight, but if the amount of starch is less than 25 parts by weight, there are disadvantages such as degradation of decomposition rate and economical increase in product cost. Machining becomes difficult.

In order to prevent degradation of the physical properties of the final product film according to the filling of the starch, modified starch for physical and chemical treatment of starch such as acid starch, oxidized starch, cationic starch, ester starch and ether starch is also preferable. When molding, the final filling amount of starch can be up to 5 to 60 parts by weight, but below 5 parts by weight, it is weak to have biodegradability. When it is 60 parts by weight or more, bubbles are generated in the film due to the moisture of starch itself during film formation. Difficulties follow. Therefore, in order to produce a high quality film, it is preferable to use starch, which has been dried beforehand to 5% or less of moisture.

In general, starch has three hydroxyl groups (Hydroxy groups) having hydrophilicity per unit of amylose glucose, which is treated with a binder to improve the overall physical properties of the film and to improve compatibility with the matrix resin. Preference is given to modifying to fill.

Such binders include silane-based and titanate-based binders, and silane-based binders include five kinds of functional groups such as vinyl, acrylic, amino, chloro, and phenoxy. As the titanate-based binder, one type of isopropyl triisostearoyl titanate having a long chain hydrocarbon site may be used.

In the method for treating a silane-based binder, first, the content of the binder is adjusted to an amount of 0.1 to 10 parts by weight based on the biodegradable filler, dissolved in a solvent such as water, alcohol, toluene, and the like. After mixing to achieve uniform mixing with the starch in the mixer and heated in the range of 50 ~ 160 ℃ to proceed with the silane coupling reaction.

The titanate binder also reacts as in the case of the silane binder, but there is a difference in using hexane as a solvent.

The addition amount of the binder in the present invention is in the range of 0.1 to 10 parts by weight with respect to the biodegradable filler, the optimum reaction efficiency at the time of the coupling reaction was obtained in the range of 80 to 120 ℃, the most suitable binder is amino functional group It is a silane-based binder having a.

In addition, it is recommended to use an automatic oxide as a decomposition accelerator. Such materials include unsaturated fatty acids and derivatives thereof having at least one unsaturated bond per molecule. These autooxides are substances that can be transferred to peroxides by destroying the carbon-carbon bonds of matrix resins under natural conditions. They are physically and chemically combined with matrix resins and autooxidatively decompose. It must be a material that is both commercially and widely available.

In the present invention, a combination of unsaturated fatty acid fatty acid esters is used as such a substance, and unsaturated fatty acids such as oleic acid, olenic acid, and linolenic acid, and fatty acid esters thereof may be used in combination, or corn oil may be used.

In addition to these, the above-described effects can be used in the present invention in a range not adversely affected. The autooxide is preferably added in an amount of 5 to 25 parts by weight in the concentrated masterbatch and 0.1 to 5 parts by weight in the case of forming into a film.

In addition, a surfactant may be used as an additive to enhance biodegradability and physical properties, and the amount of the surfactant is preferably added in an amount of 3 to 20 parts by weight in a concentrated masterbatch and 0.3 to 10 parts by weight when molded into a film. It is generally known to soften and aid in biodegradability.

In particular, nonionic surfactants are known to accelerate biodegradability more than anionic or cationic surfactants.

These surfactants have an average molecular weight of 9,000 or less and are based on polyoxyethylene such as polyoxyethylene oleyl ester and polyoxyethylene polyoxy-propylene block copolymer. It is preferable to use those having a modified molecular structure.

On the other hand, a plasticizer is used to improve the physical properties of the biodegradable film as well as to improve the moldability and processability of the film, and the amount of used is 1 to 20 parts by weight in the concentrated master batch and 0.1 to 10 parts by weight when molding into a film. In addition, such plasticizers include oleamides and stearamides as amides, and polyethylene waxes and paraffin waxes may be used.

In addition, the lubricant was used to improve the physical properties of the film, and the active agent is calcium stearate (Ca-Starate), barium-stearate (Ba-Stearate), zinc- stearate (Zn-Stearate), aluminum-stearate ( A1-Stearate), magnesium stearate (Mg-Stearate) and the like can be used, the amount of the biodegradable film is preferably used in the range of 10 to 300ppm based on metal ions.

Concentrated master batch of the present invention can be easily mixed with ordinary high density polyethylene in a suitable ratio to form a film, and the obtained component-filled biodegradable film is disposable hygiene in addition to general packaging films such as shopping bags, garbage bags, inner and outer packaging, agricultural films, etc. Suitable for use in bags and disposable sanitary gloves.

The biodegradable concentrated masterbatch according to the present invention is prepared by mixing a matrix resin with a biodegradable filler, an autooxide, and a plasticizer and an appropriate additive in a constant ratio; Melting and mixing using a mixer; The melt is melted and extruded using an extruder; It can be prepared in pellet form with a pelletizer.

The concentrated masterbatch and the high density polyethylene resin thus prepared may be blended at an appropriate ratio to form a press-molded film, a flat film, and a blown film using a hot press and an extruder for film production. At this time, if the processing temperature of the film is too high, it is important to maintain the proper processing temperature because the film is likely to discolor or bubbles.

Analysis of the processed starch filled biodegradable film measures mechanical properties using a tensile tester, and the surface of the film is measured with a scanning electron microscope.

In addition, the test was conducted according to ASTM G 21-70 to examine the degree of biodegradation of the film, and the soil reclamation test was performed to examine the biodegradation behavior in the actual environment.

Hereinafter, the present invention will be described in more detail with reference to the following Examples.

However, it is not limited to the Example of this invention.

Example 1

Manufacture of starch filled biodegradable concentrated masterbatch

First, 10 parts by weight of a silane having an amino group is dissolved in 100 ml of an aqueous 90% methanol solution, and then mixed with starch in a Littleford mixer, followed by heat polymerization. The moisture of the starch treated in this way is kept below 5%. The treated starch was checked for chemical modification using an infrared absorption spectrum.

High Density Polyethylene: Low Density Polyethylene: Linear Low Density Polyethylene is mixed in a ratio of 95-50: 30-5: 20-5, respectively, to make 100 parts by weight, 150 parts by weight of binder-treated starch (5% or less of water), 2 parts by weight of corn oil. , 2 parts by weight of polyethylene wax, and zinc-stearate were melted and mixed for 200 minutes on the basis of zinc ions for 15 minutes at a temperature of 138 ° C. in a mixer, and then extruded at a temperature of 125 ° C. using an extruder. To produce a highly concentrated masterbatch in the form of pellets.

Example 2

Manufacture of starch filled biodegradable high density polyethylene film

The concentrated masterbatch prepared in Example 1 was mixed with high density polyethylene so that the final product was filled with 5 to 60 parts by weight of starch, and the film was prepared using an extruder equipped with a die for blown film production.

<Specifications and processing conditions of the film extruder are as follows>

1.Screw length / width: 2.5

2. Dies gap = 1.5 mm

3. Screen: # 80 ~ 40

4. Orientation ratio of blown film vertical direction (Transeverse Direction): 2.5-45.

5. Pressure: 300 ~ 450kg.f / cm ²

6. Temperature range = 150 ~ 183 ℃

The film prepared in Example 2 was examined for mechanical properties using a tensile tester.

As a result of the measurement, tensile strength was superior to general low density polyethylene and linear low density polyethylene, and the elongation value was almost similar to that of high density polyethylene.

Table 1 shows a comparison of physical properties.

TABLE 1

※ Manufacturing sample ² : 9% filling starch

HDPE: High Density Polyethylene

LDPE: Low Density Polyethylene

L / LDPE: Linear Low Density Polyethylene

Example 3

Biodegradation Test of Starch Filled Biodegradable High Density Polyethylene Films

The ASTM G-21-70 test is performed by coating a film sample placed on a medium containing carbon sources with a suspension of five mixed group spores such as A. Niger, which is commonly found in soil. The extent to which the mold is covering the film in the record for a period of time to determine the biodegradation characteristics, the criteria are as follows.

0%: 0

When less than 10%: 1

10-30%: 2

30-60%: 3

60-100%: 4

As a result of the test, as the amount of starch increased, the mold covered the film more broadly, and after about 40 days, there was a tendency to show 3 or more in all cases where the amount of line content was 5 parts by weight or more.

In addition, in order to examine the degree of biodegradation in the real soil, soil landfill test was conducted for 1 year on general soil, and after 10 weeks, most of the starch already filled on the surface of the film was decomposed by microorganisms. After a year, biodegradation of the film was confirmed by showing a very weak tensile strength and elongation at break.

Claims (9)

Concentration of starch-filled biodegradable high density polyethylene consisting of 100 parts by weight of matrix resin, 25 to 80 parts by weight of biodegradable filler, 5 to 25 parts by weight of autooxide, 1 to 20 parts by weight of plasticizer, 3 to 20 parts by weight of surfactant and stabilizer Method of Making a Masterbatch. The method for producing a concentrated masterbatch of starch-filled biodegradable high density polyethylene according to claim 1, wherein the matrix resin is 95 to 5: 305: 20 to 5 in a mixing ratio of high density polyethylene: low density polyethylene: linear low density polyethylene. The concentrated masterbatch of starch-filled biodegradable high density polyethylene of claim 1, wherein the biodegradable filler is selected from the group consisting of ordinary starch, acid treated starch, oxidized starch, cationic starch, ester starch, eser starch and mixtures thereof. Manufacturing method. 4. The method according to claim 3, wherein the general starch as biodegradable filler is corn starch, rice starch, potato starch, tapioca starch, wheat starch and sweet potato starch. The surface of the biodegradable filler according to claim 1, 3 or 4 is a silane binder having functional groups such as vinyl, acrylic, amino, chloro and phenoxy in an amount of 0.1 to 10 parts by weight relative to the biodegradable filler. Process for preparing concentrated masterbatch of treated starch filled biodegradable high density polyethylene. The method for producing a concentrated masterbatch of starch-filled biodegradable high density polyethylene according to claim 1, wherein the autooxide is selected from the group consisting of unsaturated fatty acids such as oleic acid, fatty acid esters such as ethyl oleate or corn oil, or mixtures thereof. . The method of claim 1, wherein the plasticizer is selected from the group consisting of oleamide or stearamide, or polyethylene wax, and paraffin wax, or mixtures thereof. The method for producing a concentrated masterbatch of starch-filled biodegradable high density polyethylene according to claim 1, wherein the surfactant has a structure modified on the basis of polyoxyethylene (poly oxyeth-ylene). The method of claim 1, wherein the stabilizer is Ca-Stearate, Barium-Stearate, Zn-Stearate, Al-Stearate, Magnesium- A method for producing a concentrated masterbatch of starch-filled biodegradable high-density ethylene having an amount of 10-300 ppm based on metal ions relative to a biodegradable film, such as stearate (Mg-Stearate).