KR100465980B1 - Biodegradable resin composition - Google Patents

Abstract

Biodegradable resin composition according to the present invention and a method for producing the same are composed of aliphatic polyester resin and starch having excellent biodegradability, and improve the compatibility of starch plasticizer, starch structural breaker, aliphatic polyester and starch. It is a mixture composed of a compatibilizer and a processing agent that improves processability when manufacturing into a film, which is completely decomposed by microorganisms present in the soil during reclamation, and is quickly decomposed into harmless substances in the composting facility of garbage, As a biodegradable polymer that is completely decomposed by microorganisms present in the soil, there is an advantage that it can be used to produce environmentally friendly products such as garbage bags and vinyl.

Description

Biodegradable Resin Composition {BIODEGRADABLE RESIN COMPOSITION}

The present invention relates to a biodegradable resin composition, and more specifically, it has a biodegradable aliphatic polyester resin and starch as a main component, and the compatibility of starch plasticizer, starch structural breaker, aliphatic polyester and starch A mixture consisting of a compatibilizer for improving and a processing agent for improving processability in manufacturing into a film, the present invention relates to a biodegradable resin composition that is completely decomposed by microorganisms present in the soil during landfilling.

Existing general-purpose plastics are widely used in daily life because of their excellent mechanical properties, chemical resistance, and durability, but they do not decompose when used and disposed of, thus contaminating the environment. An environmental burden system is incurred to cover the costs.

Recently, a biodegradable waste payload envelope was prepared by mixing 30% biodegradable resin in the manufacture of waste payload bags, and the introduction of fully degradable waste payload bags is also under consideration.

In addition, the disposable packaging material, which is rapidly increasing in recent years, even though the consumption is high, the recovery is not made smoothly, so it is often left as it is, and the agricultural film is difficult to recover completely, causing huge obstacles to crop growth.

As environmental pollution caused by plastic wastes is a social problem, development of degradable resins that decompose upon disposal after a certain period of time has been actively conducted.

These types of degradable resins are classified into biodegradable resins decomposed by microorganisms present in the soil and photodegradable resins decomposed by ultraviolet rays of sunlight.

The photodegradable resins developed to date have a disadvantage in that they do not receive light when they are buried in the soil, so they do not decompose and thus lose their decomposability.

Examples of biodegradable resins include aliphatic polyesters, synthetic polymers, starch, polymers, and polylactides produced by fermenting corn and potatoes with microorganisms. The aliphatic polyester has excellent degradability, but when used alone, the extrusion property is poor, and in particular, it is difficult to use as an envelope due to its weak tear strength. Polylactide also has excellent degradability, but when used alone, its elongation is poor and its tear strength is weak, making it unsuitable for making a film and using it as an envelope.

In order to improve this problem, as mentioned in US Pat. No. 6,180,053, there is a method of preparing a biodegradable film by adding an aluminum compound to polycaprolactone to prepare pellets and then extruding the film. When the film is manufactured, the film extrusion is possible only at a low temperature of 60 ° C. or less, so that it is difficult to manufacture in a conventional film extruder, and in particular, it is not suitable for use as a film due to lack of tear strength.

In addition, as mentioned in US Pat. No. 5,844,023, there is a method of extruding a hydrophobic degradable polymer and starch by mixing with a plasticizer, glycerol, but this method also lacks the compatibility between hydrophobic polymer and hydrophilic starch and thus mechanical properties. This has the disadvantage of deteriorating.

An object of the present invention is to provide a biodegradable resin composition that is devised to solve the above problems, completely decomposed by the microorganisms present in the soil during landfill.

Another object of the present invention is to provide a biodegradable resin composition which is excellent in extrudability and slip properties of the produced film, and excellent in openness and thermal adhesiveness and excellent in biodegradability of an envelope made of such a film.

In order to achieve the above object, the biodegradable resin composition according to the present invention is a starch containing 30 to 80% by weight of aliphatic polyester, 10 to 60% by weight of starch having a moisture content of 1% or less, and 3 to 50% by weight of starch dosage. Plasticizer, starch structure breaker containing 0.01 to 2% by weight of alum and urea, compatibilizer containing 0.5 to 10% by weight of aliphatic polyester and starch in use of ethylene vinyl alcohol compound and ethylene vinyl acetate compound, And a post-processing agent containing 0.01% to 2% by weight of the total amount of the resin and the metal compound and the organic compound.

At this time, the starch plasticizer is glycerin, diglycerin, polyglycerin, ethylene glycol, propylene glycol, ethylene diglycol, ethylene triglycol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl At least one substance selected from glycol, trimetholpropane, uresil alcohol, tridisyl alcohol, nonyl alcohol, sorbitol, sorbitol acetate, sorbitol diacetate, sorbitol polyglycidyl ether, sorbitol dipropoxylate, and amino sorbitol It features.

The starch structuring agent urea and the alum compound have a weight ratio of 1: 3, and the structural formula of the alum compound is

M ₁ -M _2- (SO ₄ ) ₂ 12H ₂ O

(Wherein M ₁ : K or NH ₄ , M ₂ : Al, Ga, In, Ti, Cr, Mn, Fe, or Co)

Characterized in that consisting of.

In addition, as the compatibilizer, the ethylene vinyl alcohol compound and the ethylene vinyl acetate compound are mixed in a weight ratio of 1: 1. The ethylene vinyl alcohol compound is ethylene vinyl alcohol, polyvinyl alcohol, ethylene propylene alcohol, and ethylene isobutane It is any one material selected from ten alcohols, and the ethylene vinyl acetate compound is characterized in that any one material selected from ethylene vinyl acetate, modified ethylene vinyl acetate and ethylene acrylic acid.

As the post-processing agent, the metal compound and the organic compound are mixed in a weight ratio of 1: 1, and the structural formula of the organic compound is

R _1- (R ₂ ) _n -CO-NH ₂

(Wherein R ₁ : H or CH _3, R ₂ : Alkane, Alkene, or Alkyne-based compound,

n: an integer of 1 to 50).

Hereinafter, the biodegradable resin composition according to the present invention will be described in detail.

Biodegradable resin composition according to the present invention is a biodegradable aliphatic polyester resin and starch as a main component, a starch plasticizer, a structural breaker of starch, a compatibilizer for improving the compatibility of aliphatic polyester and starch, and a film It is a mixture composed of a processing agent to improve the workability during manufacturing.

Hereinafter, the components will be described in more detail.

(1) aliphatic polyester resin

The aliphatic polyester copolymer in the present invention has the characteristics of the high molecular compound, such as formula (1).

(Formula 1)

The aliphatic polyester copolymer according to the present invention is (1) esterification of aliphatic dicarboxylic acid and aliphatic glycol, and (2) addition of a polycondensation catalyst and a phosphorus compound to the oligomer obtained through esterification, and a temperature of 220 ° C. or higher and 1 mmHg. It is manufactured through the polycondensation process under the following vacuum.

The aliphatic polyester copolymer of Structural Formula 1 used in the present invention has a weight average molecular weight of 150,000 or more, and is excellent in processability or mechanical properties of the manufactured product when manufacturing a film or an injection molded product using a biodegradable resin composition. If it is low, the workability is poor and the mechanical properties of the workpiece are poor. In addition, the aliphatic polyester copolymer of Structural Formula 1 used in the present invention has an melting point of 60 ° C. or higher to be advantageous in molding. When melting | fusing point is less than 60 degreeC, workability will become bad at the time of shaping | molding process of film manufacture.

In preparing the aliphatic polyester copolymer of Structural Formula 1 used in the present invention, succinic acid or adipic acid is used as the aliphatic dicarboxylic acid component, and the above two components may be used as the comonomer. As the aliphatic glycol component, 1,4-butanediol, ethylene glycol or 1,6-hexanediol may be used, and one component may be used as a main component and the other component may be used as a comonomer.

The amount of biodegradable polyester in the biodegradable resin composition is suitably 30 to 80% by weight. When using less than 30% by weight, the mechanical properties such as strength and elongation of the film are insufficient, and when using more than 80% by weight It is uneconomical due to poor film extrudability and rising manufacturing cost.

(2) starch

Starch, which is a natural degradable substance, is used to dry moisture and keep moisture content less than 1%. In case of using less than 10% by weight, processability such as heat adhesiveness is insufficient during bag manufacturing after film production, and in case of using more than 60% by weight, carbonization phenomenon occurs due to weak heat resistance when manufacturing film under normal film extrusion conditions. Mechanical properties such as strength and elongation of the film become insufficient.

(3) starch plasticizer

As a plasticizer of starch, glycerin, diglycerin, polyglycerin, ethylene glycol, propylene glycol, ethylenediglycol, ethylenetriglycol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentylglycol, Compounds such as trimetholpropane, uresil alcohol, tridisyl alcohol, nonyl alcohol, sorbitol, sorbitol acetate, sorbitol diacetate, sorbitol polyglycidyl ether, sorbitol dipropoxylate, and amino sorbitol are used alone or in combination.

The amount of plasticizer used is 3 to 50% by weight of the starch injecting amount. When using less than 3% by weight, the plasticity of starch is insufficient, and the film extrudeability is poor. When using more than 50% by weight, the biodegradable resin is used. Poor workability and excessive adhesion during film extrusion make film production difficult.

(4) starch structure breaker

Starch structure destroying agents that destroy starch structure and improve plasticization of starch include urea, sodium forteium, calcium hydroxide, and alum compounds. Urea and alum compounds are mixed in a weight ratio of 1: 3. It is desirable to. At this time, the alum compound is composed of Structural Formula 2.

(Formula 2)

M ₁ -M _2- (SO ₄ ) ₂ 12H ₂ O

(Wherein M ₁ : K or NH ₄ , M ₂ : Al, Ga, In, Ti, Cr, Mn, Fe, or Co)

It is recommended to use 0.01 ~ 2% by weight of starch structuring agent. If it is less than 0.01% by weight, it is insufficient plasticization due to lack of structural destruction of starch. This adversely affects the mechanical properties of the final product.

(5) compatibilizer

Compatibilizers that improve the compatibility of aliphatic polyester and starch include compounds such as ethylene vinyl alcohol, polyvinyl alcohol, ethylene propylene alcohol, ethylene isobutene alcohol, ethylene vinyl acetate, modified ethylene vinyl acetate, and ethylene acrylic acid. It is preferable to use an alcohol compound and an ethylene vinyl acetate compound in a 1/1 weight ratio. The amount of compatibilizer used is preferably 0.5-10% by weight of aliphatic polyester and starch. If 0.5% by weight or less is used, the role of compatibilizer is insufficient, and when 5% by weight or more is used, the biodegradability is adversely affected. Get mad.

(6) Post-processing agent

Post-processing agents that improve processability in the manufacture of films include metal compounds such as glass beads, clay, mica, alumina, ceramics, calcium carbonate, and organic compounds such as stearamide and ureamide. It is preferable to mix and use by weight ratio. At this time, the organic compound is composed of Structural Formula 3.

(Structure 3)

R _1- (R ₂ ) _n -CO-NH ₂

(Wherein R ₁ : H or CH _3, R ₂ : Alkane, Alkene, or Alkyne-based compound,

n is an integer of 1-50)

The amount of the processing agent is preferably 0.01 to 2% by weight of the total resin amount. When 0.01% by weight or less is used, the effect as a processing agent is insufficient, and when 2% or more is used, the film surface is coarse and strength elongation is used. Mechanical properties are also lowered.

In the present invention, the tensile strength, elongation and tear strength were measured by the KSM3505 method, and the film extrudeability, the slip property of the film (SLIP), the opening property of the envelope were evaluated as excellent, normal, and poor. The thermal adhesiveness of the envelope was evaluated. It evaluated by KSS M1008 method.

Biodegradation was carried out according to the degradability accelerated evaluation method (Composting Method) and the measurement process of the degradable acceleration evaluation method is as follows.

The medium was composed as shown in Table 1 in accordance with the composition ratio of garbage generated in Korea, and the internal environment was adjusted as shown in Table 2, and 10g of a 30 μm film sample was added and maintained for 10 weeks to reduce the weight of the film sample. The degree of decomposition was evaluated by measuring, and the degree of decomposition (%) was calculated by the following equation. {(Weight of film sample before treatment -10 weight of film sample after treatment) / weight of film sample before treatment} × 100

Condition Set value (%) Food (white rice cake, Chinese cabbage, pork, fish cake) 39.8 Paper (computer paper, newspaper) 20.7 sawdust 5.3 Superfluous 7.3 Plastics 7.7 Rubber 4.5 leaf 14.7 system 100

Condition Set value (%) PH 7.0 Water content of the medium 60.9% Initial value of the carbon / nitrogen component of the medium 23.0 Air Speed 100ml / min Internal holding temperature 55.0 ℃

Hereinafter, the Examples of the present invention will be described in detail in comparison with various Comparative Examples. First, a description will be given of a method for producing an aliphatic polyester copolymer which is the first component of the present invention before explaining the embodiment.

<Polymerization of Aliphatic Polyester>

1.3 kg (14.5 mole) of 1,4-butanediol, 1.3 kg (11.5 mole) of succinic acid, and 4 g (0.033 mole) of trimethylol ethane were added into a reactor equipped with a stirrer and a condenser. It heated up to 130 degreeC over, and it heated up to 220 degreeC over 120 minutes, stirring. At this time, the generated side reaction water was completely discharged through the condenser. After the one-step reaction, 0.05 parts by weight of titanium titanium tetrabutoxide as a catalyst and 0.05 g of phosphoric acid as a heat stabilizer were added thereto, and the pressure in the tube was gradually reduced to 0.5 mmHg over 60 minutes, and the temperature was raised to 250 ° C at the same time. The reaction proceeded with stirring for minutes to complete the polymerization. Thereafter, nitrogen was injected into the reaction tube to pressurize and discharge the polymer to obtain an aliphatic polyester having a weight average molecular weight of 200,000.

Example 1

3.5 kg of corn starch dried at 1% in 1 kg of aliphatic polyester prepared by the polymerization reaction, 0.5 kg of glycerin as a plasticizer, 0.1 kg of sorbitol polyglycidyl ether, 0.02 kg of alum as a structural destroyer of starch, 0.01 kg of urea , 0.1 kg of ethylene vinyl acetate and 0.1 kg of ethylene vinyl alcohol were added as compatibilizers of aliphatic polyester and starch, 0.01 kg of calcium carbonate and 0.01 kg of amide compound were added as a post-processing agent to improve processability in film production. A resin mixture was prepared by mixing for 5 minutes in a mixer.

The resin mixture was extruded at an extrusion temperature of 150 to 190 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to produce chips after cooling to a blown film maker of 180 ° C. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

Comparative Example 1

1 kg of aliphatic polyester prepared by the polymerization reaction dried corn starch at 1% water content of 1%, 0.6 kg of glycerin as a plasticizer, 0.4 kg of sorbitol polyglycidyl ether, 0.04 kg of alum as a structural destroyer of starch, 0.04 kg of urea A resin mixture was prepared in the same manner as in Example 1.

The resin mixture was extruded at an extrusion temperature of 150 to 170 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to prepare chips after cooling, and then to 170 ° C. in a blown film maker. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

Comparative Example 2

9 kg of aliphatic polyester prepared by the polymerization reaction dried 1% corn starch at 1% moisture content, 0.05 kg of glycerin as a plasticizer, 0.05 kg of sorbitol polyglycidyl ether, 0.005 kg of alum as a structural destroyer of starch, 0.005 kg of urea A resin mixture was prepared in the same manner as in Example 1.

The resin mixture is extruded at an extrusion temperature of 170 to 190 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to prepare a chip after cooling to produce a chip at 185 ° C. in a blown film maker. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

Comparative Example 3

Resin mixtures were prepared in the same manner as in Example 1, except that 0.01 kg of glycerin and 0.01 kg of sorbitol polyglycidyl ether were used as starch plasticizers, and no starch destructive agent was used.

The resin mixture was extruded at an extrusion temperature of 150 to 190 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to produce chips after cooling to a blown film maker at 180 ° C. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

Comparative Example 4

A resin mixture was prepared in the same manner as in Example 1 except that 0.001 kg of ethylene vinyl alcohol was added as a compatibilizer for the aliphatic polyester and the starch.

The resin mixture was extruded at an extrusion temperature of 150 to 190 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to produce chips after cooling to a blown film maker of 180 ° C. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

Comparative Example 5

A resin mixture was prepared in the same manner as in Example 1 except that calcium carbonate and an amide compound, which were post-processing agents for improving processability, were not used.

The resin mixture was extruded at an extrusion temperature of 150 to 190 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to prepare a chip after cooling, and then to a blown film maker at 180 ° C. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

Comparative Example 6

A resin mixture was prepared in the same manner as in Example 1 except that 0.5 kg of calcium carbonate and 0.5 kg of an amide compound were used, which was a post-processing agent to improve workability during film production.

The resin mixture was extruded at an extrusion temperature of 150 to 190 ° C. in a twin screw extruder having an L / D (extruder length / extruder screw depth) of 36 to produce chips after cooling to a blown film maker of 180 ° C. A film having a thickness of 30 μm was prepared at a temperature, and then thermally bonded and cut to prepare a biodegradable bag.

The evaluation results of the mechanical properties, film extrudability, bag properties and biodegradability of the film are shown in Table 3.

division Tensile Strength (㎏ / ㎠) Elongation (%) Tear strength (㎏ / ㎝) Extrudeability of Film SLIP property of film Openness of envelopes Thermal adhesion of envelopes Biodegradability (% of weight loss) Portrait Landscape Portrait Landscape Ordinary place Folded Example 1 410 320 450 550 135 125 Great Great Great pass 99.9 Comparative Example 1 250 210 290 310 100 95 usually Great Great pass 98.7 Comparative Example 2 400 330 410 520 110 110 usually usually usually pass 98.5 Comparative Example 3 290 240 310 320 100 90 usually Great Great pass 98.6 Comparative Example 4 300 285 290 310 105 100 Great Great Great fail 99.3 Comparative Example 5 400 305 430 520 130 120 Great Bad Bad pass 98.6 Comparative Example 6 250 170 210 240 90 75 Great Great Great pass 90.5

Referring to Table 3 in detail, Example 1 is excellent in tensile strength, elongation, tear strength, extrudeability of the film, slip properties of the film, opening properties of the envelope, excellent thermal adhesiveness of the envelope and biodegradability It appears large and is suitable as a biodegradable resin composition according to the present invention.

On the other hand, the composition of Comparative Example 1 is low in aliphatic polyester, excessively high in starch, lacks compatibilizers and post-processing agents, and thus lacks tensile strength, elongation and tear strength, and has a moderate film extrusion property. The composition has a high amount of aliphatic polyester, low amount of starch, and lacks a compatibilizer and a post-processing agent, so that the tear strength is a little, the film extrusion property, the slip property of the film and the opening property of the film are normal. The composition has low amount of plasticizer of starch, no starch structure breaker, and thus lacks tensile strength, elongation and tear strength, and has moderate film extrusion property. Lack of compatibility, lack of tensile strength, elongation and tear strength, and the heat-adhesiveness of the envelope is also failed, the composition of Comparative Example 5 is a post-processing agent Since it is not used, film slippage and envelope opening property are poor, and the composition of Comparative Example 6 results in excessive plasticization of starch as a result of excessive use of the post-processing agent, resulting in insufficient tensile strength, elongation and tear strength, and insufficient biodegradability. .

As mentioned above, the biodegradable resin composition according to the present invention is a biodegradable polymer material which is not only rapidly decomposed into harmless substances in waste composting facilities but also completely decomposed by microorganisms present in the soil when it is buried in the soil. It can be used to manufacture environmentally friendly products such as garbage bags or vinyl.

In addition, the biodegradable polymer prepared from the biodegradable resin composition of the present invention can be molded into a film, foam molding is possible to manufacture a packaging buffer, injection molding is also possible to manufacture as a disposable product such as a lunch box container It is possible.

On the other hand, while the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention described in the claims below It will be understood that modifications and changes can be made.

Claims (9)

Starch structure containing 30 to 80% by weight of aliphatic polyester, 10 to 60% by weight of starch with water content of 1% or less, starch plasticizer containing 3 to 50% by weight of starch consumption, and 0.01 to 2% by weight of alum and urea Destructive agent, compatibilizer containing 0.5-10% by weight of ethylene vinyl alcohol compound and ethylene vinyl acetate compound, aliphatic polyester and starch, and 0.01-2% by weight of total resin usage Biodegradable resin composition comprising a post-processing agent. The method of claim 1, wherein the starch plasticizer is glycerin, diglycerin, polyglycerin, ethylene glycol, propylene glycol, ethylenedi glycol, ethylene triglycol, 1,2-propanediol, 1,4-butanediol, 1,5- Pentanediol, neopentylglycol, trimetholpropane, ureyl alcohol, tridisyl alcohol, nonyl alcohol, sorbitol, sorbitol acetate, sorbitol diacetate, sorbitol polyglycidyl ether, sorbitol dipropoxylate, aminosorbitol and the like Biodegradable resin composition, characterized in that at least one substance. The biodegradable resin composition according to claim 1, wherein the starch structuring agent urea and alum compound have a weight ratio of 1: 3. According to claim 3, wherein the structural formula of the alum compound M ₁ -M _2- (SO ₄ ) ₂ 12H ₂ O (Wherein M ₁ : K or NH ₄ , M ₂ : Al, Ga, In, Ti, Cr, Mn, Fe, or Co) Biodegradable resin composition, characterized in that consisting of. The biodegradable resin composition according to claim 1, wherein the ethylene vinyl alcohol compound and the ethylene vinyl acetate compound are mixed in a weight ratio of 1: 1 as the compatibilizer. The biodegradable resin composition according to claim 5, wherein the ethylene vinyl alcohol-based compound is any one selected from ethylene vinyl alcohol, polyvinyl alcohol, ethylene propylene alcohol, and ethylene isobutene alcohol. The biodegradable resin composition according to claim 5, wherein the ethylene vinyl acetate compound is any one selected from ethylene vinyl acetate, modified ethylene vinyl acetate, and ethylene acrylic acid. The biodegradable resin composition according to claim 1, wherein the metal compound and the organic compound are mixed in a weight ratio of 1: 1 as the post-processing agent. The method of claim 8, wherein the structural formula of the organic compound R _1- (R ₂ ) _n -CO-NH ₂ (Wherein R1: H or CH3, R2: Alkane, Alkene, or Alkyne-based compound, n: an integer of from 1 to 50) biodegradable resin composition.