KR101022786B1 - Polylactic acid-containing biodegradable resin composition - Google Patents

Abstract

The present invention is polylactic acid; Starch with an amylose content of less than 40% by weight; And a polylactic acid-containing biodegradable resin composition comprising a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer and a polylactic acid-containing biodegradable resin composition. Provides the sheet.

Starch, polylactic acid, biodegradable resin, sheet

Description

Polylactic acid-containing biodegradable resin composition

The present invention relates to a polylactic acid-containing biodegradable resin composition and a sheet formed therefrom, and more particularly, to a mixture of maleic anhydride and glycidyl methacrylate or maleic anhydride and octenylsuccinic anhydride as a compatibilizer. A polylactic acid-containing biodegradable resin composition comprising a mixture and a sheet molded from the polylactic acid-containing biodegradable resin composition.

Synthetic resin has been used as an indispensable material in real life due to various physical properties, stable supply, low price, and ease of manufacture and processing. However, when this synthetic resin is thrown away in the natural environment, it is not broken down and remains semi-permanent, which is a main cause of environmental pollution. Accordingly, biodegradable resins decomposed in the soil have been developed.

As biodegradable resins, polyhydroxybutylate-valerate (PHBV) produced by microorganisms, polycaprolactone (PCL), an aliphatic polyester, polylactic acid (PLA), and diol-diexide aliphatic polyesters are used. . The diol-diexide aliphatic polyesters include polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene adipate-terephthalate (PBAT), polybutylene succinate-adipate (PBSA) , Polybutylene succinate terephthalate (PBST) and the like are used. Since a molded article is manufactured only with biodegradable resin, the price is high, and there have been attempts to blend with starch, which is a natural substance, to lower the price and increase biodegradability. However, there is a disadvantage in that the compatibility between the starch and the biodegradable resin is poor, the processability is bad and the physical properties of the molded product thus prepared is poor.

As a method for increasing compatibility between starch and biodegradable resins, a method of plasticizing starch with a plasticizer and reforming it with thermoplastic starch and blending with aliphatic polyester or the like has been disclosed. For example, a method of compounding biodegradable resins by modifying thermoplastic starch by disintegrating the particles of starch by heat and pressure in an extruder has been disclosed to improve processability and physical properties (US Pat. No. 5,362,777, US Pat. 6,136,097, US Patent 6,348,524 and the like.

However, the use of thermoplastic starch alone has a limited improvement in processability and physical properties, and thus a new method for improving compatibility between starch and biodegradable resins is required. For example, Korean Patent Publication No. 10-2004-0061885 discloses a starch mixture prepared by adding a crosslinking agent, a plasticizer, and a compatibilizer to a starch and a biodegradable resin such as polycaprolactone and polylactic acid. Biodegradable resin compositions have been disclosed. Examples of the crosslinking agent include polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and the like. The compatibilizing agent includes succinic anhydride, maleic anhydride, dodecyl succinic anhydride, and decanoic succinic anhydride. Is disclosed. However, when the crosslinking agent is used as described above, elongation is remarkably lowered due to crosslinking between the starch and the plasticizer, and it is weak to impact, so that it is very difficult to prepare a resin composition having appropriate ductile and impact resistance.

On the other hand, polylactic acid among various biodegradable resins is obtained by polymerizing lactic acid or ring-opening polymerization of lactide, which is relatively inexpensive and has advantages as a raw material of biodegradable resins but has very low compatibility with starch. In particular, unlike other aliphatic polyester resins, moldings made of polylactic acid tend to be brittle and very brittle. Polylactic acid-based resin is excellent in transparency, but takes a long biodegradation period when embedded in the soil, and shows excellent biodegradability only in composting conditions. In addition, when the sheet or film is manufactured, the elongation is very low, and the heat resistance is low, there is a problem that deformation occurs in hot water. For this reason, biodegradable resins composed of polylactic acid have limited use.

Korean Patent Registration No. 242,964 discloses a polylactic acid-containing biodegradable resin composition incorporating starch having a high amylose content. That is, the patent discloses a biodegradable resin composition consisting of starch having an amylose content of 40 to 80% by weight and polylactic acid having a number average molecular weight of 10,000 or more, and using biodegradable starch having an amylose content of 40% by weight or more. And it is disclosed that the human friendliness is excellent. However, since starch with an amylose content of 40 wt% or more must be used as an essential, there is a limitation in commercial application due to high manufacturing cost.

The inventors of the present invention use various low-amylose starch to reduce the elongation, easily break it, and have low heat resistance. Thus, the present inventors have developed various resin compositions having improved properties of resins made of polylactic acid having deformation properties in hot water. The study was conducted. As a result, a starch of low amylose content is blended with polylactic acid using a specific combination of compatibilizers, i.e., a mixture of maleic anhydride and glycidyl methacrylate, or a mixture of maleic anhydride and octenylsuccinic anhydride, to form a resin. When prepared, it was found that the resin obtained was not only excellent in biodegradability and heat resistance, but also significantly increased in elongation at break.

Accordingly, an object of the present invention is to provide a polylactic acid-containing biodegradable resin composition comprising a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer.

It is also an object of the present invention to provide a sheet molded from the polylactic acid-containing biodegradable resin composition.

According to one aspect of the invention, polylactic acid; Starch with an amylose content of less than 40% by weight; And a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer is provided.

The content of the starch may be 10 to 900 parts by weight based on 100 parts by weight of polylactic acid, and the content of the compatibilizer may be 0.01 to 10 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of polylactic acid. . More preferably, the compatibilizer may be a 1: 0.1-9 (weight ratio) mixture of maleic anhydride and glycidyl methacrylate or a 1: 0.1-9 (weight ratio) mixture of maleic anhydride and octenylsuccinic anhydride. have.

The biodegradable resin composition of the present invention comprises 1 to 50 parts by weight of a plasticizer based on the total weight (100 parts by weight) of starch and polylactic acid; 0.01 to 5 parts by weight of lubricant; 1 to 50 parts by weight of inorganic material; And 0.01-5 parts by weight of an initiator, and may further include at least one additive selected from the group. The plasticizer may be at least one selected from the group consisting of glycerin, sorbitol, 1,4-butanediol, ethylene glycol, glucose, propylene glycol, urea, polyethylene glycol, and polypropylene glycol, and the lubricant is wax, ethylenebisstea At least one selected from the group consisting of aramid, mineral oil, and glycerin fatty acid ester, and the inorganic material is selected from the group consisting of talc, calcium carbonate, magnesium stearate, calcium sulfate, barium sulfate, clay, talc, and leadstone. At least one species may be selected, and the initiator may be at least one species selected from the group consisting of benzoyl peroxide, potassium persulfate, and dicumylperoxide.

According to another aspect of the present invention, a sheet molded from the polylactic acid-containing biodegradable resin composition is provided.

The polylactic acid-containing biodegradable resin composition according to the present invention has a property of high elongation at break and excellent heat resistance, so that the resin is made of polylactic acid having low elongation and brittle, low heat resistance and deformation in hot water. Characteristics can be effectively improved. In particular, the polylactic acid-containing biodegradable resin composition according to the present invention has a low price of low amylose content by using a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer. Starch can be used, and the resin composition obtained further has excellent biodegradability and human friendliness. Therefore, economic production of the biodegradable resin composition is possible. The polylactic acid-containing biodegradable resin composition according to the present invention has excellent biodegradability, weather resistance, heat resistance, and processability.

The present invention is polylactic acid; Starch with an amylose content of less than 40% by weight; And a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer.

The resin composition of the present invention contains a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer. The mixing ratio of the maleic anhydride and glycidyl methacrylate may be in the weight ratio range of 1: 0.1 to 9, preferably in the range of about 1: 0.4 to 3, more preferably in the range of about 1: 0.6 to 1.5. . In addition, the mixing ratio of the maleic anhydride and octenyl succinic anhydride may be in the weight ratio range of 1: 0.1 to 9, preferably about 1: 0.4 to 3, more preferably in the weight ratio range of about 1: 0.6 to 1.5. . When using a mixture of maleic anhydride with glycidyl methacrylate or octenylsuccinic anhydride as a compatibilizer according to the present invention, the resulting biodegradable resin has superior elongation at break (i.e. , Flexibility). In addition, when using a compatibilizer as described above, by enabling the use of starch having a low amylose content, it is possible to produce an economical biodegradable resin. The content of the compatibilizer may range from 0.01 to 10 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of polylactic acid.

The polylactic acid is obtained by polymerizing lactic acid or ring-opening polymerization of lactide, preferably polylactic acid having a number average molecular weight of 10,000 to 1,000,000, more preferably 50,000 to 300,000, but is not particularly limited.

As the starch, conventional starch may be used. For example, corn starch, potato starch, sweet potato starch, wheat starch, tapioca starch, rice starch, or modified starch thereof may be used alone or in combination. Of these, the use of starch having a low amylose content is economically inexpensive, and thus may be preferably used. The amylose content may be in the range of less than 40% by weight, preferably about 15 to 35% by weight. The content of the starch may be in the range of 10 to 900 parts by weight based on 100 parts by weight of polylactic acid, preferably 40 to 250 parts by weight, more preferably 60 to 150 parts by weight.

The resin composition of the present invention may further include at least one additive selected from the group consisting of a plasticizer, a lubricant, an inorganic substance and an initiator, and preferably 1 to 3 plasticizers based on the total weight (100 parts by weight) of starch and polylactic acid. 50 parts by weight; 0.01 to 5 parts by weight of lubricant; 1 to 50 parts by weight of inorganic material; And 0.01-5 parts by weight of an initiator, and may further include at least one additive selected from the group.

The plasticizer converts starch into amorphous form by penetrating between starch and starch, weakening hydrogen bonds between starch molecules and losing starch intrinsic crystallinity. The hydroxyl group of the obtained starch reacts with the terminal group of the compatibilizer to increase lipophilicity, thereby improving compatibility with polylactic acid. The plasticizer may be at least one selected from the group consisting of glycerin, sorbitol, 1,4-butanediol, ethylene glycol, glucose, propylene glycol, urea, polyethylene glycol, and polypropylene glycol, and more preferably glycerin. .

The lubricant may be at least one selected from the group consisting of waxes, ethylene bis stearamides, mineral oils, and glycerin fatty acid esters, preferably mineral oils. The inorganic material may be at least one selected from the group consisting of talc, calcium carbonate, magnesium stearate, calcium sulfate, barium sulfate, clay, talc, and leadstone. In addition, the initiator may be at least one selected from the group consisting of benzoyl peroxide, potassium persulfate, and dicumyl peroxide.

The resin composition according to the present invention can be prepared by extruding a mixture of the above components. The extrusion conditions are not particularly limited, and may be preferably performed at an extrusion rate of 200 to 400 rpm, preferably about 300 rpm, and a feeding rate of 10 to 100 rpm, preferably about 40 rpm. In addition, a conventional extruder can be used as an extruder, For example, the twin extruder which has a three stage barrel can be used. At this time, the temperature of each barrel may be in the range of 50 to 230 ° C, preferably 170 to 200 ° C.

The present invention includes a sheet molded from the polylactic acid-containing biodegradable resin composition described above. The sheet can be produced by molding the polylactic acid-containing biodegradable resin composition described above using a conventional method such as a sheet molding machine. Conditions for sheet forming include, for example, forming temperature (i.e., barrel temperature and die temperature) of 150 to 230 캜, preferably 170 to 200 캜, extrusion speed of about 500 rpm, raw material feeding rate of about 100 rpm, and roll speed. It may be prepared under conditions such as about 200 rpm. The resulting sheet can be processed into various types of products, such as disposable food containers, seedling pots, packaging cases and the like. 1 shows examples of products obtained by processing a molded sheet from a polylactic acid-containing biodegradable resin composition according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are intended to illustrate the invention and should not be construed as limiting the invention.

Example 1.

5 kg corn starch (amylose content: 25%), 5 kg polylactic acid (NatureWorks LLC 2002D), 1 kg glycerin, 0.05 kg maleic anhydride, 0.05 kg glycidyl methacrylate, 1 kg talc, 0.5 kg mineral oil, benzoyl peroxide After mixing 0.01 kg, and extruded to prepare a biodegradable resin composition. The extruder used was a twin extruder having a screw diameter of 44 mm, the extrusion speed is 300 rpm, the raw material input speed is 40 rpm, the barrel temperature was 180 ℃. The properties of the obtained biodegradable resin composition showed a pellet form (FIG. 2).

The sheet was manufactured by the sheet molding machine using the biodegradable resin composition obtained above, the barrel temperature at the time of sheet molding was 180 degreeC, and the die temperature was 190 degreeC. The extrusion speed was 500 rpm, the raw material input speed was 100 rpm, the roll speed was 200 rpm to prepare a sheet having a thickness of 1mm.

Example 2.

Biodegradable resin compositions and sheets were prepared in the same manner as in Example 1, using 0.05 kg of octenyl succinic anhydride instead of glycidyl methacrylate.

Example 3.

4 kg corn starch (amylose content: 25%), 6 kg polylactic acid (NatureWorks LLC, 2002D), 1 kg glycerin, 0.05 kg maleic anhydride, 0.05 kg glycidyl methacrylate, 1 kg talc, 0.5 kg mineral oil, 0.01 benzoyl peroxide After mixing the kg, a biodegradable resin composition and sheet were prepared in the same manner as in Example 1.

Example 4.

6 kg corn starch (amylose content: 25%), 4 kg polylactic acid (NatureWorks LLC, 2002D), 1 kg glycerin, 0.05 kg maleic anhydride, 0.05 kg glycidyl methacrylate, 1 kg talc, 0.5 kg mineral oil, 0.01 benzoyl peroxide After mixing the kg, a biodegradable resin composition and sheet were prepared in the same manner as in Example 1.

Example 5.

Using 1 kg of sorbitol instead of glycerin, a biodegradable resin composition and sheet were prepared in the same manner as in Example 1.

Example 6.

Using 1 kg of calcium carbonate instead of talc, a biodegradable resin composition and sheet were prepared in the same manner as in Example 1.

Example 7.

Biodegradable resin compositions and sheets were prepared in the same manner as in Example 1, using tapioca starch (amylose content: 17%) instead of corn starch.

Comparative Example 1.

5 kg of corn starch (amylose content: 25%), 5 kg of polylactic acid (NatureWorks LLC, 2002D), 1 kg of glycerin, 1 kg of talc, 0.5 kg of mineral oil, and 0.01 kg of benzoyl peroxide, were mixed in the same manner as in Example 1. Biodegradable resin compositions and sheets were prepared.

Comparative Example 2

After mixing 5 kg of corn starch (amylose content: 25%), 5 kg of polylactic acid (NatureWorks LLC, 2002D), 1 kg of glycerin, 1 kg of maleic anhydride, 0.1 kg of talc, 1 kg of mineral oil, 0.5 kg of mineral oil, and 0.01 kg of benzoyl peroxide, Biodegradable resin composition and sheet were prepared in the same manner as in 1.

Comparative Example 3

Biodegradable compositions and sheets were prepared in the same manner as in Example 1, using 0.05 kg polyethylene glycol diglycidyl ether instead of glycidyl methacrylate.

Test Example 1. Measurement of Properties

Using the biodegradable resin composition prepared in Examples and Comparative Examples, a physical specimen was prepared by an injection molding machine. The temperature during injection molding was set at 200 ° C. The physical properties, ie melt flow index, tensile strength, elongation at break, flexural strength and flexural modulus were measured using the obtained physical specimens. Melt flow index was measured according to ASTM D1238 at 190 ° C and 2.16 kg, and tensile strength and elongation at break were measured according to ASTM D638. Flexural strength and flexural modulus were measured in accordance with ASTM D790, Rockwell hardness was measured in accordance with Izod impact strength, ASTM D785 in accordance with ASTM D256. The results are shown in Table 1 and Table 2 below.

Example Comparative example One 2 3 4 5 6 7 One 2 3 Tensile Strength (kg / cm ² ) 240 260 270 180 250 230 220 270 250 270 Elongation at Break (%) 40 35 45 32 34 35 38 2 6 4

Melt flow index
(g / 10 min) Flexural strength
(kg / cm ² ) Flexural modulus
(kg / cm ² ) Izod
Impact strength
(kgcm / cm) Rockwell Hardness
(R scale) Example 1 7 350 18,000 4 98 Comparative Example 1 4 410 22,000 One 101 Comparative Example 2 5 380 20,000 2 95 Comparative Example 3 4 430 28,000 One 97

As can be seen from the results of Tables 1 and 2, when maleic anhydride and glycidyl methacrylate or maleic anhydride and octenylsuccinic anhydride were used (Examples 1 to 6), and when not used (comparative example) 1) It shows higher elongation at break and impact strength compared to the case where only maleic anhydride is used (Comparative Example 2) or when the maleic anhydride and polyethylene glycol diglycidyl ether are used (Comparative Example 3). Has

Test Example 2 Biodegradability Test

A container prepared by molding the sheet prepared in Example 1 and the sheet made of polylactic acid was embedded in the ground, and taken out after 1 week and 8 weeks, and the progress of decomposition was measured as in FIG. 3A. As can be seen in Figure 3a, even after two months of reclamation, the container formed of a sheet made of polylactic acid could not be visually confirmed the progress of decomposition, but the container formed of the sheet of Example 1 was mold due to the action of soil microorganisms. Was breeding. Therefore, it can be seen that the resin composition according to the present invention has excellent biodegradability compared to polylactic acid. 3B is a photograph when four weeks have elapsed since the pot formed from the sheet of Example 1 was buried in the ground. It can be seen from FIG. 3b that the fungus has been propagated by the action of soil microorganisms and has excellent biodegradability.

Test Example 3 Weather Resistance Measurement

The elongation and tensile strength of the material specimens obtained from Example 1 and polylactic acid were measured by ultraviolet rays, and the results are shown in FIGS. 4A and 4B. As can be seen in Figures 4a and 4b, the specimen obtained from polylactic acid showed a reduction in elongation and tensile strength of 50% or more after 3 days of ultraviolet irradiation, the specimen prepared in Example 1 was initially until one month after ultraviolet irradiation Since 75% or more of physical properties were maintained, it can be seen that the resin composition according to the present invention has excellent weather resistance.

Test Example 4 Measurement of Heat Resistance

The result of comparing the shape stability by temperature by pouring hot water at 60 ° C. and 90 ° C. in a container manufactured by molding the sheet prepared in Example 1 and the sheet made of polylactic acid, respectively, is shown in FIG. 5. As can be seen in Figure 5, the container formed from a sheet made of polylactic acid at a temperature of 60 ℃ or more is deformed without maintaining the shape, while the container formed from a sheet prepared in Example 1 is a temperature of 90 ℃ By maintaining the form thereof, it can be seen that the resin composition according to the present invention is very stable to excellent heat.

Test Example 5 Workability Measurement

The cooling rates of the physical specimens obtained from Example 1 and polylactic acid were compared. The cooling rate of the sheet during container processing of the sheet affects the releasability and processing time of the container from the molding mold, so that the faster the cooling rate of the sheet, the shorter the processing time, and the better the release property. It will cost. For Example 1 and the physical specimens made of polylactic acid, the time taken to cool the sheet to a constant temperature from a temperature of 150 ℃ is measured as shown in FIG. As can be seen in Figure 6, the resin composition according to the present invention can be expected to reduce the processing time and improve the releasability by showing a high cooling rate.

1 shows a molding obtained using the polylactic acid-containing biodegradable resin composition of the present invention.

2 shows the properties of the polylactic acid-containing biodegradable resin composition of the present invention.

3 shows the results of measuring biodegradability. Figure 3a is a container made by molding the sheet made of the polylactic acid-containing biodegradable resin composition of the present invention and the sheet made of polylactic acid, respectively, embedded in the ground and taken out after 1 week, 8 weeks to measure the progress of decomposition Results are shown. FIG. 3B is a photograph when 4 weeks have elapsed by embedding a pot formed from a sheet obtained from the polylactic acid-containing biodegradable resin composition of the present invention into the ground.

Figure 4 shows the results of measuring the elongation (Fig. 4a) and tensile strength (Fig. 4b) during ultraviolet irradiation to the polylactic acid-containing biodegradable resin composition of the present invention.

Figure 5 shows the heat resistance measurement results for the polylactic acid-containing biodegradable resin composition of the present invention.

Fig. 6 shows the results of processability measurement for the polylactic acid-containing biodegradable resin composition of the present invention.

Claims (8)

Polylactic acid; Starch with an amylose content of less than 40% by weight; And a mixture of maleic anhydride and glycidyl methacrylate or a mixture of maleic anhydride and octenylsuccinic anhydride as a compatibilizer. The polylactic acid-containing biodegradable resin composition according to claim 1, wherein the content of starch is 10 to 900 parts by weight based on 100 parts by weight of polylactic acid. The polylactic acid-containing biodegradable resin composition according to claim 1, wherein the content of the compatibilizer is 0.01 to 10 parts by weight based on 100 parts by weight of polylactic acid. The polylactic acid-containing biodegradable resin composition according to claim 1, wherein the compatibilizer is a 1: 0.1 to 9 (weight ratio) mixture of maleic anhydride and glycidyl methacrylate. The polylactic acid-containing biodegradable resin composition according to claim 1, wherein the compatibilizer is a 1: 0.1 to 9 (weight ratio) mixture of maleic anhydride and octenylsuccinic anhydride. According to claim 1, 1 to 50 parts by weight of a plasticizer relative to the total weight (100 parts by weight) of starch and polylactic acid; 0.01 to 5 parts by weight of lubricant; 1 to 50 parts by weight of inorganic material; And 0.01-5 parts by weight of an initiator, further comprising at least one additive selected from the group consisting of polylactic acid-containing biodegradable resin compositions. The method of claim 6, wherein the plasticizer is selected from the group consisting of glycerin, sorbitol, 1,4-butanediol, ethylene glycol, glucose, propylene glycol, urea, polyethylene glycol, and polypropylene glycol; The lubricant is selected from the group consisting of wax, ethylenebisstearamide, mineral oil, and glycerin fatty acid esters; The mineral is at least one selected from the group consisting of talc, calcium carbonate, magnesium stearate, calcium sulfate, barium sulfate, clay, talc, and leadstone; Polylactic acid-containing biodegradable resin composition, characterized in that the initiator is selected from the group consisting of benzoyl peroxide, potassium persulfate, and dicumyl peroxide. A sheet molded from the polylactic acid-containing biodegradable resin composition according to any one of claims 1 to 7.

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