KR0156892B1 - Manufacturing method of biodegradable resin - Google Patents

Abstract

The biodegradable resin of the present invention is a synthetic resin obtained by mixing 30 to 85% by weight of aliphatic polyester, 5 to 20% by weight of polyvinyl alcohol, 5 to 25% by weight of ethylene-vinyl alcohol and 5 to 25% by weight of ethylene-vinyl acetate. -99% by weight and starch 99 ~ 1% by weight together with plasticizer, lubricant and water are added to twin extruder and processed under conditions of 90 ~ 230 ℃, screw RPM 80 ~ 150, torque 40 ~ 60 The present invention provides a method for producing a biodegradable resin having excellent mechanical and physical properties by being completely decomposed by microorganisms in which it does not cause environmental pollution.

Description

Manufacturing method of biodegradable resin

The present invention relates to a biodegradable resin that is decomposed by microorganisms present in the soil at the time of disposal after use, and relates to a method for producing a biodegradable resin which is composed of natural materials and synthetic resins and does not cause environmental pollution.

In general, synthetic resins are widely used throughout the field because of their excellent physical properties such as chemical resistance, transparency, flexibility and strength, but since they do not decompose themselves after use, environmental pollution caused by waste plastics has become a social problem. The use of degradable resins in disposable products, including, is gradually expanding.

Degradable resins can be classified into biodegradable resins decomposed by microorganisms present in the soil and photodegradable resins decomposed by ultraviolet rays of sunlight. Biodegradable resins are mainly used because they do not receive light when they are buried in soil. Examples of biodegradable resins include polyhydroxyarylate resins synthesized in vivo by microorganisms and polycaprolactones, polylactides, which are synthetic polymer biodegradable resins, and aliphatic polyesters synthesized by condensation polymerization of diols and diacids. Although there are excellent biodegradability, but the price is disadvantageous.

In order to solve this problem, starch and plasticizer, which is a natural polymer, is added, kneaded and extruded under an appropriate temperature and pressure to impart degradability to non-degradable resins such as thermoplastic resins such as polyethylene, polystyrene, polypropylene, and polyethylene terephthalate. Although methods for preparing biodegradable resins are disclosed in European Patent Nos. 535,994, 32,802, 327,505, 400,532, and 404,728, starch is easily decomposed, but thermoplastic resins are not decomposed but are finely divided into soil. There is a disadvantage of remaining in the environment causing secondary environmental pollution.

Accordingly, it is an object of the present invention to provide a method for producing a biodegradable resin having excellent physical properties by being completely decomposed by microorganisms in soil upon disposal after use.

The present invention is a mixture of natural materials and synthetic resins, starch as a natural material, polyester, polyvinyl alcohol, ethylene-vinyl alcohol and ethylene-vinyl acetate as a synthetic resin, and additives to improve the workability and water as a high temperature, By kneading extrusion at high pressure to produce a biodegradable resin, the disadvantages of the above-described degradable resins are improved.

Hereinafter, the present invention will be described in detail.

The biodegradable resin of the present invention is obtained by mixing 30 to 85% by weight of polyvinyl alcohol, 5 to 25% by weight of ethylene-vinyl alcohol, and 5 to 25% by weight of ethylene-vinyl acetate copolymer as synthetic resins. 1 to 99% by weight of synthetic resin and 99 to 1% by weight of natural starch are added to the twin extruder together with a plasticizer, lubricant and water, and the conditions are 90 to 230 ° C, screw RPM 80 to 150 and torque 40 to 60. It is prepared by kneading and extruding.

Natural substances in the present invention is a starch extracted from potatoes, rice, sweet potatoes, corn and the like is composed of amylopectin having a straight amylose and branched structure, each starch can be used alone or in combination of two or more.

In the present invention, the synthetic resin is mainly composed of a dihydric alcohol and an aliphatic dicarboxylic acid, and is mainly biodegradable and compostable. Use a mixed vinyl acetate copolymer.

The polyester used in the present invention is characterized by having the same structure as the following general formula (I).

(Wherein X is composed of 0.1 to 80 mol% of phenylene residues and 20 to 99.9 mol% of aliphatic dicarboxylic acid residues, Y is an alkylene glycol residue having 6 or less carbon atoms as a main component, and the rest is the total acidic acid constituting X) It consists of the residue of the compound which has a trifunctional or more than trifunctional terminal hydroxyl group of 0.1-3 mol% of a minute.)

Among the acid components used in the present invention, a raw material component constituting a phenylene residue means one or two or more mixed configurations selected from terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl isophthalate, and the amount thereof is represented by Formula (I). About 0.1-80 mol% of all the acid component X of is suitable. When the phenylene residue is 80 mol% or more, decomposition and composting of the formed polyester becomes very difficult. As a raw material constituting the aliphatic dicarboxylic acid residue used in the present invention, succinic acid, adipic acid, sebacic acid, azeraic acid and the like can be used.

In the present invention, the material constituting the component Y of formula (I) is a residue of alkylene glycol having 6 or less carbon atoms. As a raw material, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol , 1, 6- hexanediol selected from one component or a mixture of two or more may be used. Moreover, as a compound which has a trifunctional or more than trifunctional terminal hydroxyl group of component X, the 1 component chosen from trimethylol ethane, a trimethylol propane, pentaerythritol, and dipentaerythritol, or a mixture of 2 or more types can also be used. As for the usage-amount of the compound which has a trifunctional or more than trifunctional terminal hydroxyl group, it is good to use about 0.1-3 mol% of component X. If the amount of use is more than 3 mol% crosslinking occurs in the resulting polyester to form a gel, the mechanical properties are very poor.

In the present invention, the method for preparing the copolyester is carried out in a container capable of heating and stirring the monomer components constituting X and Y of the formula (I) together with a catalyst and subjected to a condensation polymerization reaction under high temperature and high vacuum of 220 ° C or higher and 1 mmHg or lower. Let's do it. The condensation polymerization catalyst used at this time is preferably a tin compound or a titanium compound. Examples of the tin compound include tin oxides such as tin oxide and tin oxide, halogenated tin salts such as tin oxide, tin chloride, and monosulfide, monobutyl tin oxide, dibutyl tin oxide, monobutyl hydroxy tin oxide, Organotin compounds such as dibutyltin dichloride, tetraphenyltin, and tetrabutyltin are included, and titanium-based compounds include tetrabutyl titanate, tetramethyl titanate, tetraisopropyl titanate, and tetra (2-ethylhexyl) Tannetite etc. can be used.

The thermal stabilizer used in the present invention may be a phosphorus compound, for example, monoethyl phosphate, trimethyl phosphate, tributyl phosphate, trioctyl phosphate, monophenyl phosphate, triphenyl phosphate and derivatives thereof, phosphorous acid, triphenyl phosphite , Trimethylphosphoric acid and its derivatives, Iganox 1010, Iganox 1222, Igafos 168, Phenylphosphonic acid, and the like. Phosphoric acid, trimethyl phosphoric acid, triphenyl phosphoric acid and the like are excellent in effect.

The polyvinyl alcohol used in the present invention has a saponification degree of 50 to 99%, and the content thereof is preferably 5 to 20% by weight of the total amount of the total synthetic resin. In addition to starch, polyester and polyvinyl alcohol, an ethylene-vinyl alcohol copolymer and an ethylene-vinylacetate copolymer may be used in combination. Ethylene-vinyl alcohol copolymer is a high melting point compound having an ethylene content of not more than 44 mol%, preferably 5 to 25% by weight of the total amount of the synthetic resin. The ethylene-vinylacetate copolymer has a vinyl acetate content of 2 to 20 mol%. The content is characterized in that 5 to 25% by weight of the total amount of the synthetic resin.

In addition, a plasticizer, a lubricant, and the like may be added to improve processability in the manufacture of biodegradable resins. As a plasticizer, 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.As a lubricant, triglycerol monoester array, triglycerol distea array, tri Glycerol triste array is added alone or in combination. The amount of plasticizer added is preferably 10 to 50% by weight relative to starch in water, 1 to 5% by weight relative to total biodegradable resin, and 1 to 5% by weight relative to the total composition.

The biodegradable resin manufacturing method according to the present invention is supplied to the composition while supplying enough water to gelatinize the starch between the closed pores in the twin-screw extruder to melt and extrude by applying heat. The water content of the resin discharged through the die during extrusion is adjusted to 10-30% of the total biodegradable resin. The biodegradable resin is produced by melting and mixing in a barrel at a temperature of 90 to 230 ° C., a screw RPM of 80 to 150, and a torque of 40 to 60. The biodegradable resins prepared in this way are capable of various molding processes such as injection molded articles, extruded molded articles, sheets, and films.

The degradability of the degradable resin thus prepared was measured in a film state by the compost method. The composition of the compost method was composed as shown in the following Table 1 as the composition ratio of waste generated in Korea, and the internal environment was adjusted as shown in Table 2, and the sample was buried to measure the weight loss for 10 weeks to evaluate the degree of decomposition.

Hereinafter, the present invention will be described in detail in the Examples.

Synthesis Example 1

1310.7 g (21.218 mole) of ethylene glycol, 857 g (7.257 mole) of succinic acid, 1,143 g (5.888 mole) of dimethyl terephthalate and 5 g (0.037 mole) of trimethylolpropane were added to a reactor equipped with a stirrer and a condenser and manganese acetate as a catalyst. 1.0g was added, the temperature in the reactor was heated up to 120 degreeC over 30 minutes from normal temperature, and it heated up to 220 degreeC over 120 minutes, stirring. At this time, the side reaction product, methanol and water, is completely discharged through the condenser. Subsequently, 1.5 g of tetrabutoxy titanate as a catalyst and 0.4 g of phosphoric acid as a heat stabilizer were added, and the pressure was gradually reduced to 0.5 mmHg over 45 minutes, and the reaction was stirred for 180 minutes while the temperature was raised to 280 ° C. After proceeding, the stirring was stopped and nitrogen was injected into the tube to pressurize and discharge the polymer to obtain a desired polyester.

Synthesis Example 2

1,187 g (19.124 moles) of 1,4-butanediol, 649 g (4.441 moles) of adipic acid, 862 g (4.440 moles) of dimethyl terephthalate and 5 g (0.037 moles) of pentaerythritol were added to a reactor equipped with a stirrer and a condenser. 1.0 g of manganese acetate is added to increase the temperature in the reactor to 120 ° C. over 30 minutes from room temperature and to a temperature of 220 ° C. over 120 minutes with stirring. Subsequently, 1.5 g of tetrabutoxy titanate as a catalyst and 0.4 g of phosphoric acid as a heat stabilizer were added, and the pressure in the tube was gradually reduced to 0.5 mmHg over 45 minutes, and the reaction was stirred for 180 minutes while the temperature was raised to 245 ° C. After proceeding, the stirring was stopped and nitrogen was injected into the tube to pressurize and discharge the polymer to obtain a desired polyester.

Example 1

20% by weight of corn starch, 80% by weight of synthetic resin, synthetic resin 46% by weight of polyester synthesized in Synthesis Example 1, 18% by weight of polyvinyl alcohol having a saponification degree of 80%, ethylene-vinyl alcohol copolymer (ethylene content 44 mol%) 20% by weight, 10% by weight of ethylene-vinyl acetate copolymer and 2% by weight of triglycerol nosterate were mixed with a lubricant, and 4% by weight of glycerin and 10% of water were added as a plasticizer. Biodegradable resin pellets were prepared by melting, mixing and extruding in the extruder under the following conditions.

● Extrusion condition

Screw Speed: 80

Torque: 40

-Barrel temperature: 110/150/190/210/180/160 ℃

Example 2

It is the same as Example 1 except having used the polyester synthesize | combined by the synthesis example 2 instead of the polyester synthesize | combined by the synthesis example 1 with respect to Example 1.

Example 3

Compared to Example 1, the synthetic resin content was 40% by weight of polyester, 8% by weight of polyvinyl alcohol having a saponification degree of 80%, 20% by weight of ethylene-vinyl alcohol copolymer (44% by mole of ethylene), and 20% by weight of ethylene-vinylacetate. It is the same as Example 1 except having added%.

Example 4

Compared to Example 2, the synthetic resin content was 50% by weight of aliphatic polyester, 16% by weight of polyvinyl alcohol having a saponification degree of 80%, 8% by weight of ethylene-vinyl alcohol copolymer, and 20% by weight of ethylene-vinylacetate. Same as Example 1.

Example 5

15 parts by weight of corn starch, 85 parts by weight of synthetic resin, 65% by weight of polyester synthesized in Synthesis Example 1, 5% by weight of polyvinyl alcohol having a degree of saponification of 80%, and 10% by weight of ethylene-vinyl alcohol (44% by mole of ethylene) It is the same as Example 1 except having used 14 weight% of ethylene-vinylacetate copolymers.

Example 6

It carried out similarly to Example 5 except having used the polyester synthesize | combined by the synthesis example 2 instead of the polyester synthesize | combined by the synthesis example 1.

The pellets prepared in Examples were prepared as a blown film to evaluate the elongation and degradability to obtain the results shown in Table 3.

Claims (9)

In preparing a biodegradable resin containing a polyester copolymer as a main component, a starch and a plasticizer, a polyester having a structure of the following general formula (I), polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene 1 to 99% by weight of the decomposable synthetic resin obtained by mixing the copolymer together with vinyl acetate, 99 to 1% by weight of starch extracted from corn, potato, rice, sweet potato, etc., and a plasticizer and an emulsifier are added, followed by melting and kneading. Method of producing biodegradable resins. (Wherein X is composed of 0.1 to 80 mol% of phenylene residues and 20 to 99.9 mol% of aliphatic dicarboxylic acid residues, Y is an alkylene glycol residue having 6 or less carbon atoms as a main component, and the rest is the total acidic acid constituting X) It consists of the residue of the compound which has a trifunctional or more than trifunctional terminal hydroxyl group of 0.1-3 mol% of a minute.) The phenylene residue in X component is terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl isophthalate, and the aliphatic dicarboxylic acid residue is one or two selected from succinic acid, adipic acid, sebacic acid, azeraic acid. A method for producing a biodegradable resin, characterized in that used by mixing more than one species. The method of claim 1, wherein the alkylene glycol residues in the Y component is one or two selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol A method for producing a biodegradable resin, characterized by using a mixture of the above. The method of claim 1, wherein the compound having a tri- or higher functional terminal hydroxyl group is used in the production of biodegradable resins, characterized in that one or two or more of trimethylol ethane, trimethylolpropane, pentaerythritol, and dipentaerythritol are used in combination. Way. The method for producing a biodegradable resin according to claim 1, wherein the polyvinyl alcohol has a degree of saponification of 50 to 99% and the amount of the polyvinyl alcohol used is 5 to 20% by weight based on the total synthetic resin. The method of claim 1, wherein the ethylene-vinyl alcohol copolymer has an ethylene content of 27 to 44 mol%, and the amount of the ethylene-vinyl alcohol copolymer is 5 to 25 wt% with respect to the total synthetic resin. The method for producing a biodegradable resin according to claim 1, wherein the ethylene-vinylacetate has a vinyl acetate content of 2 to 20 mol% and an amount of 5 to 25 wt% with respect to the total synthetic resin. The plasticizer according to claim 1, wherein 10 to 50% by weight of water is added to the starch and a mixture of one or two or more of glycerin, ethylene diglycol, polyethylene glycol, and 1,4-butanediol is added to the total biodegradable resin. A method for producing a biodegradable resin, characterized in that 1 to 5% by weight is added. According to claim 1, The lubricant is triglycerol monostearate, triglycerol distearate, triglycerol tristearate is mixed with one or two or more kinds of 1 to 5% by weight based on the total biodegradable resin, characterized in that The manufacturing method of biodegradable resin made into.