KR0146849B1 - Biodegradable resin composition - Google Patents

Abstract

The present invention relates to a biodegradable resin composition, and more specifically, a synthetic polymer composed of 10 to 55% by weight of starch, an ethylene-vinyl alcohol copolymer, polycaprolactone, aliphatic polyester, etc. By mixing the emulsifier, the flow promoter and the plasticizer to melt-extruded under high temperature and high pressure to manufacture the pellet, and using this to the biodegradable resin composition which can be molded for the use of disposable injection molded articles, sheets, films and packaging materials. It is about.

Description

Biodegradable Resin Composition

The present invention relates to a biodegradable resin composition, and more specifically, a synthetic polymer composed of 10 to 55% by weight of starch, an ethylene-vinyl alcohol copolymer, polycaprolactone, aliphatic polyester, etc. To a biodegradable resin composition which is melt-extruded under high temperature and high pressure by adding an emulsifier, a flow promoter, and a plasticizer, to form pellets for use in disposable injection molded articles, sheets, films, and packaging materials. will be.

In general, synthetic resins are widely used in various fields because of their excellent physical properties, but since they do not decompose themselves after use, biodegradable resins that can be fully decomposed in the field of disposable products including packaging films have recently emerged as environmental problems caused by waste plastics. There is an active research on.

Degradable resins include biodegradable resins decomposed by microorganisms present in 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, which are synthetic polymer resins.

In order to solve this problem, in order to impart biodegradability to non-degradable resins such as polyethylene, polystyrene, polypropylene, polyethylene terephthalate, thermoplastic resins, water or plasticizers are added to the starch, which is a natural polymer, to destroy the starch structure. Patents for obtaining thermoplastic mixtures at temperature and pressure are described in European Patent Nos. 535,994, 32,802, 327,505, 400,532, 404,728 and the like, but such resins are difficult to improve the filled material to a certain amount or more, Starch, a natural polymer, decomposes, but thermoplastic resins decompose into indivisible pieces and remain in the soil, causing secondary environmental pollution.

Accordingly, it is an object of the present invention to provide a biodegradable resin composition having excellent mechanical and physical properties and economical efficiency because it is completely decomposed by microorganisms in soil after use.

In order to achieve the above object as well as another object easily expressed in the present invention, polycaprolactone, which is a synthetic polymer-based biodegradable resin, and an aliphatic polyester, starch and resin added to improve mechanical properties and processability instead of thermoplastic resins. In order to improve compatibility, the resin copolymer decomposable by microorganisms composed of added ethylene-vinyl alcohol copolymer was melt-kneaded with starch to obtain a biodegradable resin composition which improved the disadvantages of the existing degradable resin.

The present invention is described in more detail as follows.

Melt-kneading under high temperature and pressure by mixing emulsifier, plasticizer and additives by mixing 10 ~ 55% by weight of natural starch, 45 ~ 90% by weight of synthetic resin composed of ethylene-vinyl alcohol copolymer, polycaprolactone and aliphatic polyester To obtain a biodegradable resin composition satisfying various characteristics.

Starch, a natural polymer, is extracted from potatoes, flesh, tapioca, corn, etc., or a mixture of chemically unmodified starch or chemically modified starch composed mainly of amylose having a linear structure and amylopectin having a branched structure. In particular, the present invention used corn starch consisting of 27% amylose and 73% amylopectin.

In the present invention, polycaprolactone was used as a microbial decomposable synthetic resin copolymerized with starch. Since polycaprolactone has a low melting point and low glass transition temperature, when used alone, it may cause viscosities at the time of molding, poor contact feeling, and poor moldability due to low crystallization rate of the polymer.

Therefore, in order to improve these disadvantages, by using an aliphatic polyester together, it was possible to prepare a resin having excellent mechanical properties and biodegradability and improved processability. The aliphatic polyester used in the present invention has the property of high melt viscosity and melt strength, and improves the slow crystallization rate of polycaprolactone, and improves the hydrophilic property of starch, thereby forming a film into a mixture having improved mechanical properties and processability. This was possible. The aliphatic polyester has one component selected from succinic acid or an ester compound and 1,4-butanediol as main components. In addition, the monomer for controlling the crystal behavior is 1 to 30 mol% based on one component selected from succinic acid, succinic anhydride and succinic acid ester compound, 0.01 to 1 mol% of a compound having a trifunctional or higher polyfunctional phase Added. The reaction conditions are esterification and transesterification reaction at a temperature of 220 ° C. or lower, and then the esterification or transesterification product is added to a reactor equipped with a condenser and a stirrer, and a thermal stabilizer, a catalyst, and other aids are added to the high vacuum of 1 mmHg or less. The aliphatic polyester obtained by polycondensation reaction at the temperature of 260 degreeC or less under the following was used. At this time, the aliphatic polyester used has a melting point of 90 ~ 115 ℃, the weight average molecular weight of 100,000 to 260,000 is a high molecular weight polymer, 10 to 70% by weight based on the total synthetic resin component is used.

It is preferable that polycaprolactone resin has melting | fusing point of 60 degreeC, and the molecular weight has the characteristic of 80,000 or more. When the molecular weight is low, it is not preferable because it is unsuitable for the required physical properties, and 10 to 60% by weight of the total synthetic resin component is used.

In addition, the ethylene-vinyl alcohol copolymer has a hydrophilic group and a hydrophobic group, thereby improving compatibility with starch and the hydrophobic group of the microbial decomposable resin, and serves to impart excellent mechanical properties and excellent durability.

The ethylene-vinyl alcohol copolymer used in the present invention has an ethylene content of 27 to 44%, a melting point of 160 to 190 ° C, a density of 1.14 g / cm ³ , a vitrification transition temperature of 55 to 62 ° C, and a melt index of 8 to 12g / It is preferable that it is 10min. The ethylene-vinyl alcohol copolymer was used in an amount of 10 to 40% by weight based on the total synthetic resin components.

The starch used in the present invention was a corn starch containing 12% moisture content, 15 to 45% by weight of water starch as a plasticizer and a single or a mixture selected from glycerin, ethylene diglycol, polyethylene glycol and 1,4-butanediol. Add 1 to 5% by weight of the total composition, add an additive to lower the gelatinization temperature to destroy the starch structure, and melt in an extruder to knead four components such as synthetic polycaprolactone, aliphatic polyester, and ethylene-vinyl alcohol copolymer. Extrude. Then, 1 to 2% by weight of triglycerol monostearate was added as an emulsifier and kneaded and extruded to obtain a degradable resin composition having excellent mechanical properties.

The composition thus formed is melt extruded while injecting sufficient water in APV MP 2030 (30 mm, L / D 25) twin-screw extruder to inject water so that the starch is destroyed in the hermetic space in the barrel. At this time, the moisture content of the final material coming out through the die is controlled by using a vacuum pump to be 3 ~ 15%. The barrel temperature is 60 ~ 220 ℃, the squeegee speed is 80 ~ 150, and the torque is extruded under the conditions of 40 ~ 60 to make biodegradable resin and molded for the use of disposable injection molding foam, sheet, film and packing materials. This made it possible.

The following Examples and Comparative Examples illustrate the present invention more specifically, but do not limit the scope of the present invention.

Synthesis Example 1

136 g (1.5108 mol) of 1,4-butanediol, 12 g (0.1152 mol) of 2,2-dimethyl-1,3-propanediol, 137 g (1.1601 mol) of succinic acid, 0.7 g of trimethylol ethane in a reactor equipped with a stirrer and a condenser (0.0052 mole) and 1.02 g (0.0003 mole) of catalyst slurry were added, and the temperature in the reactor was raised to 120 ° C. over 40 minutes from normal temperature, and the temperature was increased to 210 ° C. over 120 minutes with stirring. At this time, the generated side reaction water was completely discharged through the condenser. Subsequently, the pressure was gradually reduced to 0.5 mmHg over 45 minutes and the stirring reaction was performed for 120 minutes while the temperature was raised to 245 ° C. Then, the stirring was stopped and nitrogen was introduced into the tube to pressurize and discharge the polymer. An aliphatic polyester copolymer having a weight average molecular weight of 235,000 and a melting point of 105.7 ° C was obtained.

Synthesis Example 2

The aliphatic polyester copolymer having a weight average molecular weight of 218,000 and a melting point of 106.6 ° C was obtained in the same manner as in Synthesis example 1 except that 1.1 g (0.0057 mol) of trimellitic anhydride was used instead of trimethylol ethane.

Synthesis Example 3

An aliphatic polyester copolymer having a weight average molecular weight of 264,000 and a melting point of 106.3 ° C was obtained in the same manner as in Synthesis Example 1, except that 0.8 g (0.0060 mol) of trimethylol propane was used instead of trimethylol ethane.

Example 1

15 parts by weight of corn starch, 80 parts by weight of synthetic resin, 45 parts by weight of the aliphatic polyester prepared in Synthesis Example 1 with respect to synthetic resin, 30 parts by weight of polycaprolactone with respect to synthetic resin, 25 with ethylene-vinyl alcohol copolymer Add parts by weight, 4 parts by weight of glycerin, 1 part by weight of triglycerol monostearate, 0.5 parts by weight of urea, and add 12 to 40% water content to starch (Twin-Screw Extruder). The biodegradable resin was prepared by mixing and extruding, and the physical properties thereof were evaluated, and the results are shown in Table 1.

Screw Speed (RPM): 150

Torque: 50

Extruder Barrel Temperature: 70/148/186/192/165/126

Example 2

Except for using the aliphatic polyester prepared in Synthesis Example 2 was carried out in the same manner as in Example 1, the physical properties were evaluated and the results are shown in Table 1.

Example 3

Except having used the aliphatic polyester manufactured by the synthesis example 3, it carried out similarly to Example 1, and evaluated the physical property, and the result is shown in Table 1.

Example 4

20 parts by weight of corn starch, 75 parts by weight of synthetic resin, 30 parts by weight of the aliphatic polyester prepared in Synthesis Example 1 with respect to synthetic resin, 50 parts by weight of polycaprolactone with respect to synthetic resin, 20 parts by weight of ethylene-vinyl alcohol copolymer Except having used a weight part, it carried out similarly to Example 1, and shows the result in Table 1.

Example 5

Except having used the aliphatic polyester manufactured by the synthesis example 3, it carried out similarly to Example 1, and shows the result in Table 1.

Comparative Example 1

15 parts by weight of corn starch, 80 parts by weight of synthetic resin, 75 parts by weight of polycaprolactone to synthetic resin, 25 parts by weight of ethylene-vinyl alcohol copolymer to synthetic resin, and the results are the same as in Example 1. It described in 1.

Comparative Example 2

20 parts by weight of corn starch, 75 parts by weight of synthetic resin, polycaprolactone was carried out in the same manner as in Example 1 except that 80 parts by weight of synthetic resin and 20 parts by weight of ethylene-vinyl alcohol copolymer were used. It is shown in Table 1.

Blown films were prepared from the biodegradable resins prepared in Examples and Comparative Examples, and subjected to elongation and biodegradability tests, and the results are shown in Table 1.

● Film manufacturing

The film manufacturing equipment manufactured the film of 40-55 micrometers after the barrel temperature was 80/135/140/140 degreeC using HAAKE's "RHEOCORD 90" equipment of die diameter of 25 mm.

● biodegradability evaluation

Biodegradability assessment was determined by the COMPOST method. This method has a useful effect in landfills by inducing biodegradation and conversion to safe organic products. The measuring method is to mature solid wastes with a moisture content of 60% or more at a temperature of 55 to 60 ° C under aerobic conditions to mediate the activity of the high temperature active fungi present in the solid wastes, thereby reducing the carbon dioxide produced by the weight loss and microbial metabolism of the polymer sample. The amount of generation was measured to determine the degree of decomposition. Degradability evaluation results measured in this manner for 45 days are listed in Table 1.

Claims (7)

Biodegradable resin characterized by melting and kneading 10 ~ 55% by weight starch, 45 ~ 90% by weight synthetic resin consisting of polycaprolactone, aliphatic polyester copolymer and ethylene-vinyl alcohol copolymer Composition. The biodegradable resin composition according to claim 1, wherein the polycaprolactone used has a molecular weight of 80,000 or more and a melting point of 60 ° C. The biodegradable resin composition according to claim 2, wherein the polycaprolactone is used in an amount of 10 to 60% by weight based on the total synthetic resin. The biodegradable resin composition according to claim 1, wherein the aliphatic polyester copolymer used has a weight average molecular weight of 200,000 to 260,000 and a melting point of 90 to 115 ° C. The biodegradable resin composition according to claim 4, wherein the aliphatic polyester copolymer is used in an amount of 10 to 70% by weight based on the total synthetic resin. The biodegradable resin composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer used has an ethylene content of 44%, a melting point of 160 to 190 ° C, a density of 1.14 g / cm ^{3 and a} melt index of 8 to 12 g / 10 minutes. . The biodegradable resin composition according to claim 6, wherein the amount of the ethylene-vinyl alcohol copolymer is 10 to 40% by weight based on the total synthetic resin.