KR20010073648A - Biodegradable synthetic resin composition using the remnants of starch - Google Patents

Abstract

The present invention relates to a biodegradable resin composition prepared by mixing starch extracted from carbohydrate foods with a non-degradable resin. The biodegradable resin composition according to the present invention is composed of 1 to 99% by weight of non-degradable synthetic resin and 99 to 1% by weight of starch residue, and then melted and kneaded after addition of conventional plasticizers and lubricants generally used in the production of synthetic resins. The present invention provides a new biodegradable resin composition having excellent degradability and mechanical properties in a low cost and simple manner by preparing a biodegradable resin using starch dregs that are disposed of as waste instead of starch.

Description

Biodegradable resin composition using starch residue {BIODEGRADABLE SYNTHETIC RESIN COMPOSITION USING THE REMNANTS OF STARCH}

The present invention relates to a biodegradable resin composition obtained by extracting starch from carbohydrate foods, that is, starch dregs, and more specifically, a new biodegradable resin composition having excellent degradability and physical properties made by mixing starch dregs with a non-degradable resin. It is about.

Synthetic resin, a petrochemical product, has various uses in various fields such as films, sheets, molded products, foam materials, pipes, hoses, plates, etc., despite its short history due to its excellent properties such as rigidity, flexibility, transparency, chemical resistance, processability, and economy. Is being used. However, most of the synthetic resin products are resistant to microorganisms, so they do not decompose in the natural ecosystem after disposal, causing serious environmental pollution problems. Accordingly, researches on degradable resins that can decompose in the natural ecosystem are being actively conducted.

Currently, degradable resins include photodegradable resins decomposed by ultraviolet rays and biodegradable resins decomposed by microorganisms present in the soil. Biodegradable resins are biodegradable resins synthesized by microbiological or chemical methods, polyethylene, polypropylene, etc. Biodegradable resins are filled with non-degradable resins of biodegradable raw materials such as starch, which is a natural substance.

Since the photodegradable resin is decomposed only when it is exposed to sunlight (ultraviolet rays), there are problems such as costs that do not decompose when the waste is buried in the soil, cost issues, and the hazards of added transition metals. It is hard to see the effect in a country where it is. Accordingly, more attention is focused on the development of biodegradable resins that can be degraded in the natural ecosystem by microorganisms such as bacteria and bacteria.

Biodegradable resins include polyhydroxyarylate resins synthesized in vivo of microorganisms and polycaprolactones, polylactides, which are synthetic polymer biodegradable resins, and aliphatic polyesters synthesized by condensation polymerization of diols and diacids. There is this. However, these biodegradable resins do not replace the existing non-degradable resins due to the disadvantages of excellent biodegradability but deterioration in physical properties, cost-effectiveness, and above all, high price.

On the other hand, biodegradable resins filled with biodegradable materials such as natural polymers, especially starch-filled biodegradable resins, despite the theoretical shortcomings of starch filling due to deterioration of properties and processability and short-term degradation of starch, As a new polymer material, research and commercialization are being actively conducted in terms of abundant and cheap raw material prices and the method that the effect can be seen at the earliest. Addition of natural polymers such as starch and plasticizers to thermoplastic resins such as polyethylene, polystyrene, polypropylene, polyethylene terephthalate, etc. to EP 535,994, 32,802, 327,505, 400,532, 404,728, etc. A method of producing a biodegradable resin by kneading and extruding under and pressure is disclosed.

However, in general, in applying starch to a non-degradable synthetic resin, there are largely the following problems. First, starch has very low compatibility with hydrophobic general purpose resins, which are hydrophilic having three polar hydroxyl groups in one unit structure. Second, since starch usually contains 10 ~ 13% of water, it is not only incompatible with general purpose resins but also can cause a sharp drop in product properties due to bubble generation during mixing, extrusion and molding under high temperature and high pressure. If the product is a film, the impact is very large. Third, since starch contains 0.6-0.8% of lipid component, it is known to affect plastic properties. In addition, starch in which most of these biodegradable resins are mixed is easily decomposed, but other polymers are not decomposed but remain in the soil as fine pieces, causing secondary environmental pollution. It is considered that decomposition is not made completely because it is not uniformly distributed in the continuous phase of the polymer phase of the resin.

In order to solve the problems as a raw material of the starch as described above, the method of lowering the starch content of the starch to 1% or less, including miniaturizing the particle size of the starch (US. PAT. 4,016,117, 4,021,388), having a straight chain structure among the starch Method of using amylose starch (US. PAT. 3,891,620), copolymerization of acrylic monomers such as acrylic acid or alkyl acrylate to polyethylene, polypropylene, etc., and mixing the copolymer into starch (US. PAT. 4,133,784, 5,087,650 ), A method of denaturing and using starch by imparting hydrophobicity through starch-based silicone treatment (US. PAT. 4,125,495), decomposition of starch granules melted and disordered molecular structure by heating starch above melting point and glass transition temperature Method using the prepared starch (European Patent Application Nos. 84,300,940.8, 88,0455.1, 88810548.3, 89810046.6) (Domestic Patent No. 185201, No. 1) 78389) and other methods of using modified starch in which starch is modified in acetic acid and the like (Domestic Patent Publication No. 96-7756) are known.

However, the above methods for processing and modifying starch have high manufacturing costs and are only a very limited improvement in the physical properties of plastics, films or foamed products, and do not obtain a clear improvement in physical properties. In particular, in the case of a degradable film whose physical properties decrease rapidly with increasing amount of starch, especially low density polyethylene film, even if only 8% or more of starch is actually added, it is difficult to commercialize the product as a film and maintain physical properties. Therefore, the starch-filled biodegradable resins of the past have a problem that the quality of the product is low in terms of physical properties, although the price is relatively higher than that of the conventional non-degradable resin products, and it is widely used to replace non-degradable resins in disposable products. It was a difficult situation to be.

Therefore, the inventors of the present invention are finding carbohydrates that are degradable and economical as starch as biodegradable materials that can replace starch instead of the modification and processing methods of starch, which are expensive and relatively ineffective. The present invention has been completed by focusing on the fact that the residue left after extracting starch from foods is composed mainly of fiber and has a smaller moisture content than starch.

The present invention is an inexpensive material that can be easily obtained in place of methods of increasing the manufacturing cost such as modifying and processing starch, and does not have a problem of deterioration of physical properties such as starch. The residue left after extracting starch from carbohydrate foods It is an object of the present invention to provide a new biodegradable resin that solves the conventional problems in terms of biodegradability and physical properties, that is, fully decomposable in a natural ecosystem, and having excellent physical properties such as strength.

In order to achieve the above object, in the present invention, 1 to 99% by weight of non-degradable synthetic resin and 99 to 1% by weight of the residue left after extracting starch from carbohydrate food are used, and a general plasticizer generally used in the production of synthetic resins. And a biodegradable resin composition prepared by melting and kneading after adding a lubricant. .

Hereinafter, the present invention will be described in detail.

The biodegradable natural material used in the present invention uses fiber-based waste left after extracting starch from carbohydrate foods. Starch is extracted from starch-based carbohydrate foods such as rice, wheat, barley, corn, sweet potatoes, potatoes, flour, tapioca, and oyster roots, resulting in a large amount of fiber and waste. Some lignin and semicellulose are included. Since this residue (hereinafter referred to as "starch residue") is less water content than starch, unlike starch, which is difficult to fill more than 15%, 20% or more can be filled without deteriorating physical properties, and 99% of the filling is depending on the processing purpose. It is also possible. In addition, starch dregs are excellent in physical properties when mixed with synthetic resin, which is considered to play a role of reinforcing agent in the mixture since starch dregs are rigid based on fiber.

Non-degradable synthetic resins used in the present invention, although not particularly limited, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol, ethylene-vinyl acetate, polyvinyl chloride, polyvinylidene chloride, acrylic resin, poly Amide resins, unsaturated polyester resins, polycarbonate resins and copolymers thereof can be used. In addition, conventional non-degradable synthetic resins may be selectively used according to various processing purposes such as plastics, molded products, films, packaging films, and foamed products.

The biodegradable resin of the present invention is composed of 1 to 99% by weight of the non-degradable synthetic resin and 99 to 1% by weight of starch dregs, and is a common plasticizer and lubricant commonly used in the production of synthetic resins for improving processability. After the addition with water as necessary, kneading and extrusion under the conditions of 80 to 250 ℃, screw RPM 90 to 150, torque 40 to 70 to prepare.

As the plasticizer of the present invention, water, glycerin, ethylene diglycol, polyethylene glycol, 1,4-butanediol, or the like may be used alone or as a mixture of two or more thereof, and as a lubricant, triglycerol monostearate and triglycerol distearate And triglycerol tristearate are added alone or in combination. The amount of plasticizer added is 5 to 50% by weight with respect to starch residue in water, 0.5 to 6% by weight with respect to the total biodegradable resin, and 0.2 to 8% by weight with respect to the total composition. Do.

In addition, heat stabilizers may be optionally used in the present invention as needed. Thermal stabilizers include, but are not limited to, phosphorus compounds such as phosphoric acid, monoethyl phosphoric acid, trimethyl phosphoric acid, tributyl phosphoric acid, trioctyl phosphoric acid, monophenyl phosphoric acid, triphenyl phosphoric acid and derivatives thereof, phosphorous acid, triphenyl phosphoric acid, trimethyl phosphoric acid and derivatives thereof Iganox 1010, Iganox 1222, Igafos 168, phenylphosphonic acid and the like can be used, and particularly preferably monoethyl phosphoric acid, trimethyl phosphoric acid and the like can be used.

In the present invention, a method for producing a pellet of biodegradable resin is melted and extruded by adding heat to the composition while supplying a small amount of water to a closed space in a twin-screw extruder. The water content of the resin discharged through the die during extrusion is adjusted to 5 to 50% of the total biodegradable material. The temperature in the barrel is melted and mixed under the conditions of 80 to 250 ° C, screw RPM 90 to 150, torque 40 to 70, and the like to produce a biodegradable resin.

The biodegradable resin prepared as described above can be molded in various forms such as injection molded articles, extruded molded articles, sheets, films, foam molded articles, and the like, and can be used as general plastic household goods, packaging materials such as vinyl, packaging containers such as styrofoam, etc. It can be used in various ways.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited to these examples.

Example 1

10% by weight of starch residue and 90% by weight of polyethylene are mixed with 1% by weight of triglycerol distearate as a lubricant, 2% by weight of ethylene diglycol as a plasticizer and 10% of water to starch residue. Biodegradable resin pellets were prepared by melting, mixing, and extruding at a screw speed of 90 RPM, torque 40 and the following barrel temperature conditions in an extruder (barrel temperature: 110/150/180/210/190/160 ° C.).

Example 2

Biodegradable resin pellets were prepared in the same manner as in Example 1, except that 15% by weight of starch residue and 85% by weight of polyethylene were mixed.

Example 3

Biodegradable resin pellets were prepared in the same manner as in Example 1, except that 20% by weight of starch residue and 80% by weight of polyethylene were mixed.

Example 4

Biodegradable resin pellets were prepared in the same manner as in Example 2, except that polyvinyl alcohol having a degree of saponification of 80% was used instead of polyethylene.

Example 5

Biodegradable resin pellets were prepared in the same manner as in Example 2, except that polypropylene was used instead of polyethylene.

Example 6

Biodegradable resin pellets were prepared in the same manner as in Example 2, except that ethylene-vinyl acetate was used instead of polyethylene.

Example 7

Explode Rating

The degradability of the biodegradable resins prepared in Examples 1 to 6 was measured in a film state by the compost method. The composition of the Compost method was prepared as shown in Table 1 so as to be equal to the general domestic waste composition ratio, and the internal environment was adjusted as shown in Table 2, and the sample was buried to measure weight loss for 12 weeks and completely decomposed at 24 weeks. The degree of decomposition was evaluated by checking whether or not. The evaluation results are shown in Table 3 below.

ingredient content(%) Food (rice, cabbage, pork, fish cake) Paper (newspaper, magazine) Sawdust Chorizo Plastic rubber leaves 39.820.75.37.37.74.514.7 100

ingredient content(%) pH Moisture Content Carbon / Nitrogen Initial Value Air Supply Temperature 7.06023 100ml / min55 ℃

sample Weight loss (%): 12 weeks Complete decomposition: 24 weeks Example 1 52 ○ Example 2 55 ○ Example 3 61 ○ Example 4 56 ○ Example 5 51 ○ Example 6 49 ○

Example 8

Mechanical property measurement

The pellets prepared in Examples 1 to 6 were prepared as a blown film to measure mechanical properties in terms of strength and elongation. The results are shown in Table 4 below.

sample Tensile Strength (㎏ / ㎠) Elongation (%) Example 1 460 48 Example 2 458 46 Example 3 457 45 Example 4 452 47 Example 5 467 46 Example 6 461 44

As can be seen from the above examples, the present invention provides a new resin composition having excellent degradability and mechanical properties in a low cost and simple manner by preparing a resin composition using starch waste which is discarded as waste instead of starch as a biodegradable material. It is effective. Therefore, the biodegradable resin composition according to the present invention can be used to replace existing non-degradable resins in a wide range of synthetic resin applications, such as plastic containers, packaging materials such as vinyl, disposable products such as styrofoam, and the present invention is a waste that is discarded Recycling starch waste also contributes to environmental conservation.

Claims (4)

It is melted and kneaded after adding 1 ~ 99% by weight of non-degradable synthetic resin and 99 ~ 1% by weight of remaining starch residue from carbohydrate food and adding the usual plasticizer and lubricant commonly used in the manufacturing process of synthetic resin. Biodegradable resin composition, characterized in that. The method of claim 1, The composition is a biodegradable resin composition comprising 75 to 90% by weight of non-degradable synthetic resin and 25 to 10% by weight of starch residue. The method of claim 1, The non-degradable synthetic resin is polyethylene, polypropylene, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol, ethylene-vinyl acetate, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polyamide resin, unsaturated polyester resin, polycarbonate resin And biodegradable resin composition, characterized in that selected from the group consisting of these copolymers. The method according to any one of claims 1 to 3, The starch residue is a residue left after extracting starch from carbohydrate food selected from rice, wheat, barley, corn, sweet potato, potato, flour, tapioca, and 칡 root, and contains a large amount of fiber, a little lignin, and semicellulose. A biodegradable resin composition comprising: a) component.