KR960005075B1 - Biodegradable polyethylene compositions using starch with polymerizable-functional group and their manufacture - Google Patents

Abstract

To increase the physical property of biodegradable polymer, the starch that has a polymerizable functional group is synthesized and polymerized with the matrix resin by radical initiator. As the biodegradable starch, the maleic acid ester starch or methacrylic acid ester starch containing the functional group in the range of 0.1-20% is used. The 5-400 wt. % of biodegradable starch, 100 wt.% of matrix resin, 0.01-1 wt.% of radical initiator, 0.1-10 wt.% of oxidizer and 0.1-10 wt.% of plasticizer is compounded and extruded to make a pellet. This biodegradable polyethylene film contains a high starch contents and shows a good physical property because the starch is bonded to the matrix resin by chemical reaction.

Description

Biodegradable polyethylene composition using starch having a polymerizable functional group and its manufacturing method

Figure 1 is a photograph of the cross-sectional view of the biodegradable film of Example 7 of the present invention with a scanning electron microscope (x1,200).

The present invention relates to a biodegradable polyethylene composition prepared by preparing starch having a polymerizable functional group and chemically bonding it with polyethylene, which is the most versatile olefin resin, and a manufacturing method thereof.

With the trend of increasing pollution caused by plastic products produced more than 100 million tons annually worldwide, countries around the world are preparing multi-faceted joint efforts and countermeasures to solve this problem. Attention is focused on solving the pollution problem caused by plastics. In order to solve the environmental pollution problem caused by various solid wastes including plastics, landfilling, incineration and recycling have been mainly used. However, waste disposal through reclamation and landfilling and incineration cannot completely solve the environmental problem.

The recent trend has been a great deal of attention and research and development around the world in the development of so-called degradable plastics that make the waste plastic itself degradable.

The technology related to degradable plastics is divided into biodegradation technology and photodegradation technology. In the case of starch-added polymer in biodegradation technology, G.J.L. First published by Griffin, the technique disclosed in U.S. Patent No. 4,021,388 describes the preparation of biodegradable films by surface treatment with a silane-based binder (Coupling Agent) to modify them to be lipophilic. As the starch is charged only by increasing the phosphorus binding force, it is difficult to overcome the property decrease of the film.

In addition, US Patent Nos. 4,133,784 and 4,337,181 filed by F.H.Otey et al. Of U.S.

In Korea, there are related patent registrations and applications of G. No. 90-6336, G. No. 91-8553, and G. No. 92-2678 and 92-2685 filed by Sunil Glucose Co., Ltd. In order to increase the compatibility between the matrix resin and starch, the starch was modified to increase the lipophilicity or by using a compatibilizer to increase only the physical bonding strength between the matrix resin and the starch.

In the present invention, the synthetic resin starch is synthesized by using a radical initiator after the synthesis of starch having a polymerizable functional group by attempting to overcome the physical property of the film as the starch is filled by increasing only the physical bonding strength between the matrix resin and the starch. By having phosphorus bonds, the reduction of physical properties was minimized and the starch content was increased compared to the existing products.

An object of the present invention to provide a biodegradable polyethylene composition using a starch having a polymerizable functional group, another object is to provide a method for producing the biodegradable polyethylene composition.

In order to achieve the above object, the composition in the present invention comprises 100 parts by weight of the matrix resin, 5 to 400 parts by weight of the biodegradable filler, 0.01 to 1.0 parts by weight of the radical initiator, 0.1 to 10 parts by weight of the automatic oxidizer, and 0.1 to 10 parts by weight of the plasticizer. do. In addition, the composition may include 0.1 to 10 parts by weight of crude monomer.

The composition of the present invention will be described in more detail as follows.

Low density polyethylene (LDPE), linear low density polyethylene (LLDPE), or high density polyethylene (High Density Polyethylene: HDPE) is used as the matrix resin, and maleic acid having a polymerizable functional group is used as the biodegradable filler. Ester starch or methacrylic acid ester starch is used, and the radical initiator is benzoyl peroxide, di-tributyl peroxide, azobis isobutylnitrile, tributyl hydroperoxide, dicumyl peroxide, rupersol 101 ( Pennwalt), and also Percadox-14 (manufactured by AKZO), and the like, and as an automatic oxidizing agent, oleic acid, stearic acid, manganese stearate, manganese oleate, iron oleate [II], iron stearate [II], or mixtures thereof As the plasticizer, for example, oleamide, erucamide or viton can be used. have. In addition, the co-monomer may be selected from one or two or more of acrylonitrile, styrene, ethyl acrylate.

In order to achieve another object of the present invention, the production method of the present invention is composed of a mixture of polyethylene and starch having a polymerization functional group, a radical initiator, an automatic oxidizing agent, a plasticizer and the like in a proportion to react and extrude. The crude monomer may be included in the above.

In the present invention, in order to reduce the manufacturing cost through the process simplification, a chemical bond is generated between the starch having a polymerization functional group and the polyethylene chain in the extruder by using a reactive extrusion method.

As a biodegradable filler having a polymerizable functional group, starch containing maleic acid functional group and methacrylic acid functional group using maleic acid and methacrylic acid functional groups, respectively, was used as maleic acid ester starch or methacrylic acid ester starch. It was dried as possible and used. The biodegradable film according to the present invention is melted or mixed in a mixer of a plastic order by mixing starch, co-monomer, radical initiator, automatic oxidizing agent, plasticizer, etc. having a polymerization functional group with polyethylene at a predetermined ratio. Each component is added, melt mixed, extruded using a compounder, and processed into pellets using a pelletizer. The processed pellets were made into a compression molded film and a blown film using a thermocompressor and an extruder for film production.

The biodegradable film was analyzed using UTM (Universal Testing Machine) to measure the mechanical properties such as tensile strength and tensile elongation, and to observe the cross-section and surface of the film by scanning electron microscopy. Was measured. Observing the cross section of the biodegradable film of Example 1 with a scanning electron microscope, it was difficult to distinguish the boundary between the polyethylene matrix and starch particles as shown in FIG. It was confirmed that the chemical bond was formed in and starch. Biodegradability evaluation was used in combination with ASTM G-21 -70 method and observation of changes in physical properties after soil reclamation.

Hereinafter, the production method and effects of the present invention will be described in more detail with reference to the following examples, which do not limit the scope of the present invention.

Method for preparing methacrylic acid ester starch

1 kg of corn starch is placed in a reactor containing 1.6 L of water and heated to 40-50 ° C. while stirring with a mechanical stirrer. 50 g of methacrylic anhydride is constantly dropped in a dropping funnel for 30 minutes, and the pH of the solution is adjusted to 9 with 3% by weight aqueous sodium hydroxide solution. After the addition, stirring was continued for 10 minutes, and then the pH was adjusted to 7 and filtered. After washing several times with distilled water and drying, 1 kg of methacrylic acid ester starch was obtained.

Preparation method of maleic acid ester starch

1 kg of corn starch is placed in a reactor containing 1.6 L of water and heated to 40-50 ° C. while stirring with a mechanical stirrer. After adding 10 g of magnesium oxide, 100 g of maleic anhydride is slowly dropped for 50 minutes. After the addition, stirring was continued for 10 minutes, and then the pH was adjusted to 5.5 and filtered. After washing several times with distilled water and drying, 1 kg of maleic acid ester starch was obtained.

Example 1.

In this embodiment, a biodegradable film is prepared by chemically bonding a polyethylene chain using methacrylic acid ester starch having a polymerizable functional group.

5 kg of low density polyethylene (MI = 3, density = 0.919), 50 g of oleamide, and 50 g of manganese oleate were added to a Henschel Mixer, and the polyethylene was coated with a solution of 3 g of benzoyl peroxide in 50 ml of acetone. Biodegradable masterbatch pellets in which starch is chemically bonded to polyethylene chains by reactive extrusion of 4 kg of coated pellets and 6 kg of methacrylic acid ester starch in an extruder maintained at an extrusion temperature of 170 ° C. and a screw speed of 250 rpm. To prepare. 1.7 kg of this biodegradable masterbatch was dry blended with 8.3 kg of linear low density polyethylene (MI = 1, density = 0.919) and then blown using a film making extruder.

The physical properties and biodegradability of the biodegradable film prepared by dry blending the above biodegradable masterbatch and linear low density polyethylene (MI = 1, density = 0.919) are shown in Table 1 below.

Biodegradability was determined by incubating the fungus on the film for at least 21 days according to ASTM G 21-70 method.

0%: 0

10% or less: 1

10 ~ 30%: 2

30 ~ 60%: 3

60-100%: 4

[Example 2-6.]

The content of starch was measured in the same manner as in Example 1 except that the following weight% based on polyethylene was used, and the results are shown in Table 1 below.

TABLE 1

*: Comparative Example

Example 7.

In this embodiment, maleic acid ester starch is used as a starch having a polymerizable functional group, and styrene is used as a co-monomer to increase the polymerization reactivity.

5 kg of low density polyethylene (MI = 1, density = 0.919), 50 g of oleamide, and 50 g of mangaoleate were added to a Henshel Mixer and coated on polyethylene using a solution of Percadox-14.3 g in 50 ml of acetone. A biodegradable masterbatch pellet in which starch was chemically bonded to polyethylene chain was prepared by reactive extrusion of 3 kg of coated pellet and 7 kg of maleic acid ester starch in an extruder maintained at an extrusion temperature of 160 ° C. and a 250 rpm screw speed. do. 1.7 kg of this biodegradable masterbatch was dry blended with 8.3 kg of high density polyethylene (MI = 0.28, density = 0.945) and then blown using a film making extruder.

The physical properties and biodegradability of the biodegradable film prepared by dry blending the above biodegradable masterbatch and high density polyethylene (MI = 0.28, density = 0.945) are shown in Table 2 below.

[Example 8-12.]

The content of starch was measured in the same manner as in Example 7 except that the following weight% based on polyethylene was used, and the results are shown in Table 2 below.

TABLE 2

*: Comparative Example

After the blown film was made using an extruder for making a film, the cross section of the biodegradable film was observed by scanning electron microscopy, and the boundary between the polyethylene matrix and the starch particles was unclear and the starch particles were cut into sections. As a result of analyzing the physical properties of the prepared biodegradable film, the starch content up to 20% by weight did not show any difference in tensile strength and tensile elongation compared to the basic resin.

The biodegradability evaluation was used in combination with ASTM G 21-70 method to investigate the changed form and properties after a certain period of time after soil reclamation. The biodegradability was excellent when the starch content was more than 10% by weight.

Claims (10)

Biodegradable polyethylene composition comprising 100 parts by weight of the matrix resin, 5 to 400 parts by weight of the biodegradable filler, 0.01 to 1.0 parts by weight of the radical initiator, 0.1 to 10 parts by weight of the automatic oxidizer and 0.1 to 10 parts by weight of the plasticizer. The biodegradable polyethylene composition according to claim 1, further comprising 0.1 to 10 parts by weight of a crude monomer. 3. The biodegradable polyethylene composition according to claim 2, wherein the crude monomer is selected from acrylonitrile, styrene and ethylacrylate. The biodegradable polyethylene composition according to claim 1, wherein the matrix resin is low density polyethylene, linear low density polyethylene or high density polyethylene. The biodegradable polyethylene composition according to claim 1, wherein the biodegradable filler is maleic acid starch and / or methacrylic acid ester. The biodegradable polyethylene composition according to claim 5, wherein the maleic acid functional group and the methacrylic acid functional group of maleic acid ester starch or methacrylic acid ester starch each contain 0.1 to 20%. The radical initiator according to claim 1, wherein benzoyl peroxide, di-tributyl peroxide, azobisisobutylonitrile, tributyl hydroperoxide, dicumyl peroxide, lupersol 101, percadox-14, or the like is used. Biodegradable polyethylene composition wherein the starch is chemically bonded. The biodegradable polyethylene composition according to claim 1, wherein the autooxidant is selected from one or more mixtures of manganese oleate, iron oleate (II), manganese stearate, and iron (II) stearate. The starch-bonded biodegradable polyethylene composition according to claim 1, wherein the plasticizer is selected from oleamide erucamide and viton. A method for producing a biodegradable polyethylene composition, characterized in that the reaction mixture by mixing polyethylene, starch having a polymerization functional group, radical initiator, automatic oxidizing agent, plasticizer and the like at a constant ratio.