KR100385718B1 - Biodegradable Resin Composition Containing Starch and Its Manufacturing Method - Google Patents

Abstract

The present invention relates to a biodegradable resin composition containing starch, in order to uniformly distribute the starch masterbatch having excellent mechanical properties in the matrix resin, and to improve the compatibility of the starch and the resin matrix, the biodegradable aliphatic polyester resin matrix It provides a biodegradable resin composition comprising 0-90 parts by weight, 10-100 parts by weight of starch masterbatch and 1-20 parts by weight of plasticizer based on 100 parts by weight of the resin matrix and starch masterbatch. Wherein the starch masterbatch comprises 20-90 parts by weight of biodegradable aliphatic polyester resin, 10-80 parts by weight of starch and 0.1-5 parts by weight of diisocyanate coupling agent based on 100 parts by weight of the aliphatic polyester resin and starch. have.

Description

Biodegradable resin composition containing starch and method for producing same

The present invention relates to a biodegradable resin composition containing starch, and more particularly, a starch masterbatch and biodegradable aliphatic polyester chemically bonded to starch and a biodegradable aliphatic polyester resin using a diisocyanate coupling agent. The present invention relates to a biodegradable resin composition having excellent mechanical properties consisting of a resin matrix and a plasticizer, and a method for producing the same.

Plastics continue to increase in consumption from industrial materials to disposables and packaging because of their lightness, strength, ease of processing, and ease of disassembly. Various solid wastes, such as plastics, are disposed of or recycled after reuse by landfill or incineration, but waste disposal methods such as landfill and incineration cause serious environmental damage. Therefore, in order to solve these environmental problems, various biodegradable plastics have been developed that maintain their function and structure during use, but are once decomposed into water and carbon dioxide by microorganisms.

For example, US Pat. No. 4,021,388 and European Pat. No. 409,789 describe a technique for producing biodegradable plastics by mixing starch, which is inexpensive and readily biodegradable, with non-degradable plastics such as polyethylene, polypropylene, and polystyrene. However, as the starch is added, not only the physical properties of the plastic are significantly lowered, but the starch is biodegraded upon disposal, but other matrix resins are not decomposed and remain intact.

In addition, U.S. Patent Nos. 4,133,784 and 4,337,181 disclose a method of preparing a film by adding starch in a gelatinized state to an ethylene-acrylic acid copolymer, but the ethylene-acrylic acid copolymer is expensive and the physical properties of the film are produced. It is extremely vulnerable to practical use, and has a disadvantage of poor biodegradability.

In addition, U.S. Patent Nos. 5,254,607, 5,256,711, and 5,258,430 describe techniques using gelatinized starch, but not only a separate device is needed to add excessive amounts of water and plasticizer to gelatinize the starch. And degradability of an ethylene-vinyl alcohol copolymer, which is a synthetic resin used to increase dimensional stability, has not been verified.

Finally, Korean Patent Publication Nos. 94-11542, 94-11556, and 94-11558 induce reaction extrusion using an organic acid catalyst and a binder to induce chemical bonding of starch and polyethylene. There is a possibility that the monomer remains, and when the starch content is more than 30%, the mechanical properties are significantly reduced, and polyethylene used as the matrix resin remains undecomposed.

Accordingly, an object of the present invention is to provide a biodegradable resin composition which is excellent in mechanical properties and in which the entire resin is biodegraded. In addition, an object of the present invention is to provide a biodegradable resin composition excellent in compatibility between the starch and the matrix resin, and a method for producing the same, wherein the starch masterbatch excellent in mechanical properties is uniformly distributed in the matrix resin.

1A is a photograph taken of a cross section of a resin composition according to Example 1 with a scanning electron microscope.

1B is a photograph taken of a cross section of the resin composition according to Comparative Example 1 with a scanning electron microscope.

1C is a photograph taken with a scanning electron microscope of a cross section of the starch masterbatch according to Preparation Example 1. FIG.

In order to achieve the above object, the present invention is 0-90 parts by weight of biodegradable aliphatic polyester resin matrix, 10-100 parts by weight of starch masterbatch and 1-20 parts by weight of plasticizer based on 100 parts by weight of the resin matrix and starch masterbatch. It provides a biodegradable resin composition comprising, 0.5 to 10 parts by weight of lubricant based on 100 parts by weight of the resin matrix and starch masterbatch, if necessary. Wherein the starch masterbatch comprises 20-90 parts by weight of biodegradable aliphatic polyester resin, 10-80 parts by weight of starch and 0.1-5 parts by weight of diisocyanate coupling agent based on 100 parts by weight of the aliphatic polyester resin and starch. And, if necessary, 0.5 to 10 parts by weight of lubricant based on 100 parts by weight of the aliphatic polyester resin and starch.

In addition, the present invention is 20-90 parts by weight of biodegradable aliphatic polyester resin, 10-80 parts by weight of starch and 0.1-5 parts by weight of diisocyanate-based coupling agent based on 100 parts by weight of the aliphatic polyester resin and twin-screw extruder After reaction extrusion to prepare a starch masterbatch, 10- 100 parts by weight of the starch masterbatch, 0-90 parts by weight of biodegradable aliphatic polyester resin matrix, and 1- parts by weight of the resin matrix and starch masterbatch. Provided is a method for producing a biodegradable resin composition comprising a step of kneading and extruding 20 parts by weight of a plasticizer using a twin screw extruder.

Hereinafter, the present invention will be described in detail.

In the present invention, in preparing a biodegradable resin composition composed of starch, biodegradable aliphatic polyester, plasticizer, etc., a diisocyanate coupling agent is added to aliphatic polyester resin and granular starch having excellent biodegradability, By extruding the reaction within, a starch masterbatch in which a hydroxy group of a starch and a hydroxy group of an aliphatic polyester resin terminal reacted with a diisocyanate coupling agent to form a chemical bond was used. Thus, a starch masterbatch excellent in mechanical properties is melted and uniformly distributed in a biodegradable aliphatic polyester resin matrix to prepare a biodegradable resin composition having excellent mechanical properties and compatibility between starch and polyester resin.

Biodegradable aliphatic polyester resins used in the resin matrix and the masterbatch may be different from each other, but it is preferable to use the same kinds of resins. Examples of such polyester resins include polytetramethylene succinate. Nate, polytetramethylene adipate, polypropiolactone, polycaprolactone, polylactic acid, polyhydroxybutylate-barylate copolymer and mixtures thereof. The amount of biodegradable aliphatic polyester used as the resin matrix is preferably 0-90 parts by weight based on 10-100 parts by weight of the starch masterbatch, and the amount of biodegradable aliphatic polyester contained in the starch masterbatch is 10-80 starch. 20-90 weight part is preferable with respect to weight part. In this case, the total amount of the biodegradable aliphatic polyester resin in the biodegradable resin composition is preferably 20-90% by weight of the biodegradable aliphatic polyester resin and the starch mixture, more preferably 30-80% by weight. If the amount is less than 20% by weight, the workability is not easy. If the amount is more than 90% by weight, the biodegradation rate is lowered.

Starches that can be used in the masterbatch of the present invention includes corn starch, rice starch, potato starch, tapioca starch, wheat starch, sweet potato starch and the like, pure starch, α-starch subjected to physical and chemical treatment to the starch, acid treatment Modified starches such as starch, oxidized starch, cationic starch, ester starch, ether starch and the like and mixtures thereof may be used, but corn starch is preferable in terms of the particle size and economical aspect of the starch. Such starch is generally easily biodegradable, and is composed of linear amylose and branched amylopectin, and has three hydroxyl groups per amylose glucose unit, which is hydrophilic and has strong hydrogen bonds. In the starch master batch, 10-80 parts by weight of starch is used based on 20-90 parts by weight of aliphatic polyester resin, and the total amount of starch in the composition of the present invention is 8-80% by weight, more preferably 20-70% by weight. It is good to be%. If less than 8% by weight, economical benefits are less, the rate of biodegradability is lowered, and if it is more than 80% by weight, compatibility with the polyester resin is reduced.

The diisocyanate-based coupling agents used in the preparation of the starch masterbatch of the present invention each have a -NCO group at the terminal, and one side reacts with the hydroxyl group of the starch to form a chemical bond, and the other is at the terminal of the aliphatic polyester resin. By reacting with a hydroxyl group to form a chemical bond, the interfacial adhesion between the incompatible starch and the biodegradable aliphatic polyester resin is improved, and the interfacial separation phenomenon is suppressed. Therefore, the masterbatch itself may not only improve processability and mechanical properties as compared to the existing resin composition, but may also improve mechanical properties of the composition by adding the masterbatch to the biodegradable aliphatic polyester resin matrix. Examples of diisocyanate-based coupling agents that can be used in the present invention include hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, naphthalene 1,5-diisocyanate, diphenylmethane 2,4'-diisocyanate, diphenylmethane 4.4'-diisocyanate, phenylene diisocyanate, polymethylene polyphenylene polyisocyanate or these And mixtures thereof.

The diisocyanate coupling agent is preferably used in an amount of 0.1-5 parts by weight based on 100 parts by weight of the aliphatic polyester resin and the starch of the masterbatch, if the amount is less than 0.1 parts by weight, the interfacial adhesion is reduced, 5 Exceeding parts by weight reduces the biodegradability rate of the masterbatch.

The resin composition of the present invention is preferably 0.5-20 parts by weight, more preferably 1-20 parts by weight of a plasticizer, based on 100 parts by weight of the resin matrix and starch masterbatch in order to improve physical properties of the resin and improve processability. It is good to add. As such a plasticizer, it is preferable to use water, glycerin, ethylene glycol, polyethylene glycol, propylene glycol, sorbitol, lactic acid or a mixture thereof.

In addition, in the resin composition of the present invention, in order to improve the fluidity of the resin composition and mold release properties in the mold during the preparation and molding of the resin composition, 0.5-10 parts by weight of a lubricant is added to 100 parts by weight of the resin matrix and the starch master batch. Preferably, 0.5-10 parts by weight of lubricant is added to the starch masterbatch based on aliphatic polyester resin and 100 parts by weight of starch. Such lubricants include fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, fatty acid esters such as glycerol monostearate, glycerol monooleate, ethylene bis stearamide, ester complexes, fatty alcohols, and the like. You may mix and use 2 or more types of said lubricants.

The starch masterbatch according to the present invention is reacted and extruded at 120-210 ° C. using a twin screw extruder equipped with an aliphatic polyester, starch in the particulate state and a diisocyanate-based coupling agent which can maintain a high shear force and a long residence time. It can manufacture. If the extruder temperature is lower than 120 ° C., the reaction between the coupling agent, the polyester and the starch does not proceed smoothly, and if it exceeds 210 ° C., the pyrolysis of starch occurs. In the production of the starch masterbatch, when a plasticizer is used together with a diisocyanate coupling agent, starch, and an aliphatic polyester, the diisocyanate coupling agent reacts with the hydroxyl group of the plasticizer, thereby interfacial adhesion between the starch and the biodegradable aliphatic polyester resin. And it is not preferable because there is a disadvantage that the physical properties are reduced. In addition, if the starch is gelatinized using a plasticizer and then the gelatinized starch is dispersed in the resin matrix, a larger amount of starch may be used than in the case of using non-gelatinized starch. There is a disadvantage of falling strength.

10-100 parts by weight of the starch masterbatch prepared in this way, 0-90 parts by weight of the aliphatic polyester resin matrix, a suitable amount of lubricant and plasticizer using a twin screw extruder equipped with a screw that can maintain a high shear force and a long residence time The biodegradable resin composition pellets of the present invention can be prepared by kneading and extruding again at 120-210 ° C. At this time, if the amount of the starch master batch is too low, the starch content is not so low that there is no economic benefit, and the biodegradation rate is lowered, which is not preferable. The pellets thus prepared contain about 0.5-1% by weight of water.

As in the present invention, the starch and aliphatic polyester in the form of a plasticizer is not contained, and the starch masterbatch is prepared by first chemically bonding the diisocyanate and then dispersing it in the composition containing the plasticizer. Starch may be gelatinized with a plasticizer to produce a biodegradable resin composition having a uniform domain of 1 micrometer or less and having excellent mechanical properties.

The biodegradable resin composition of the present invention is not only used to prepare disposable injection molding products such as golf tees, bottles, sheets, packaging materials, etc. through injection molding, blow molding, extrusion molding, thermoforming, etc., but also compression using a film extruder. It can be used to make molded films, flat films, blown films and the like. In addition, using the biodegradable resin composition according to the present invention as a master batch, polyethylene, polypropylene, polystyrene, polyvinylacetate, polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, styrene-acrylonitrile copolymer, acrylo It is also possible to produce biodegradable resins by mixing with non-degradable thermoplastic resins such as nitrile-butadiene-styrene copolymers and polycarbonates.

Hereinafter, preparation examples, examples and comparative examples of the masterbatch according to the present invention will be described. However, the following examples are merely illustrative of the present invention and do not limit the present invention.

[Master Batch Production Example 1]

50 parts by weight of corn starch (13% water content), 50 parts by weight of polycaprolactone as a biodegradable aliphatic polyester resin, and 0.5 parts by weight of hexamethylene diisocyanate with respect to 100 parts by weight of the composition, followed by high shear force and long A starch masterbatch was prepared in pellet form by reaction extrusion at a temperature of 190 ° C. using a twin screw extruder equipped with a screw capable of inducing a residence time of 35 L / D.

[Master Batch Production Example 2]

30 parts by weight of corn starch (13% of water) and 70 parts by weight of polycaprolactone were used as the biodegradable aliphatic polyester resin.

[Master Batch Production Example 3]

60 parts by weight of corn starch (13% moisture), 40 parts by weight of polycaprolactone as a biodegradable aliphatic polyester resin, and 3 parts by weight of dicyclohexylmethane 4,4'-diisocyanate based on 100 parts by weight of the composition Then, it carried out similarly to the manufacture example 1.

[Master Batch Production Example 4]

The same procedure as in Production Example 1 was conducted except that 0.1 part by weight of hexamethylene diisocyanate was used as the diisocyanate coupling agent.

[Master Batch Production Example 5]

The same procedure as in Preparation Example 1 was repeated except that 50 parts by weight of corn starch (water content of 0.5%) and 2 parts by weight of diphenylmethane 4,4′-diisocyanate were dried in a vacuum oven at 130 ° C. for 48 hours.

[Master Batch Production Example 6]

The same procedure as in Preparation Example 1 was repeated except that 50 parts by weight of corn starch (water content of 0.5%) and 5 parts by weight of 1,4-cyclohexane diisocyanate were dried in a vacuum oven at 130 ° C. for 48 hours.

Example 1

20 parts by weight of polycaprolactone, a biodegradable aliphatic polyester resin, 80 parts by weight of a starch masterbatch prepared by the method of Preparation Example 1, and 15 parts by weight of glycerin as a plasticizer were added to 100 parts by weight of the composition. The biodegradable resin composition was prepared in pellet form by extruding at 190 ° C. using a twin screw extruder having a L / D of 35 with a time inducing screw. The pellets were used to make injection specimens to measure physical properties and biodegradability. The results are shown in Table 1.

Example 2

Extrusion specimens were prepared in the same manner as in Example 1, except that 40 parts by weight of the starch masterbatch prepared in Preparation Example 1 was used. The physical properties and biodegradability thereof were measured, and the results are shown in Table 1.

Example 3

Extrusion specimens were prepared in the same manner as in Example 1, except that 40 parts by weight of polycaprolactone and 60 parts by weight of starch masterbatch prepared by the method of Preparation Example 1 were used as the biodegradable aliphatic polyester resin matrix. The biodegradability was measured and the results are shown in Table 1.

Example 4

10 parts by weight of polycaprolactone and 90 parts by weight of starch masterbatch prepared by the method of Preparation Example 1 were used as the biodegradable aliphatic polyester resin matrix, and 15 parts by weight of glycerin as a plasticizer and lactic acid (Lactic acid) with respect to 100 parts by weight of the composition. Except for the use of 5 parts by weight was prepared in the same way as in Example 1, the physical properties and biodegradation was measured for this, and the results are shown in Table 1.

Example 5

Extrusion specimen was prepared in the same manner as in Example 1 except that 10 parts by weight of polycaprolactone and 90 parts by weight of the starch masterbatch prepared by the method of Preparation Example 2 were used as the biodegradable aliphatic polyester resin matrix. The biodegradability was measured and the results are shown in Table 1.

Example 6

Except that 10 parts by weight of polycaprolactone and 90 parts by weight of starch masterbatch prepared by the method of Preparation Example 3 were used as the biodegradable aliphatic polyester resin matrix, and 20 parts by weight of glycerin was used as a plasticizer based on 100 parts by weight of the composition. Injection specimens were prepared in the same manner as in Example 1, and their physical properties and biodegradability were measured, and the results are shown in Table 1.

Example 7

Extrusion specimen was prepared in the same manner as in Example 1, except that 20 parts by weight of polycaprolactone and 80 parts by weight of starch masterbatch prepared by the method of Preparation Example 4 were used as the biodegradable aliphatic polyester resin matrix. The biodegradability was measured and the results are shown in Table 1.

Example 8

Extrusion specimens were prepared in the same manner as in Example 1, except that 20 parts by weight of polycaprolactone and 80 parts by weight of starch masterbatch prepared by the method of Preparation Example 5 were used as the biodegradable aliphatic polyester resin matrix. Figures were measured, and the results are shown in Table 1.

Example 9

As a biodegradable aliphatic polyester resin matrix, 20 parts by weight of polycaprolactone and 80 parts by weight of starch masterbatch prepared by the method of Preparation Example 6 were used, and 10 parts by weight of glycerin and 5 parts by weight of sorbitol were used as a plasticizer based on 100 parts by weight of the composition. Except for the use, the injection specimens were prepared in the same manner as in Example 1, and the physical properties and biodegradability thereof were measured, and the results are shown in Table 1.

Example 10

Extrusion specimen was prepared in the same manner as in Example 1, except that 50 parts by weight of polycaprolactone and 50 parts by weight of starch masterbatch prepared by the method of Preparation Example 6 were used as biodegradable aliphatic polyester. Was measured, and the results are shown in Table 1.

Comparative Example 1

40 parts by weight of corn starch (13% moisture), 60 parts by weight of polycaprolactone as a biodegradable aliphatic polyester resin using a twin screw extruder with a L / D of 35 with a screw capable of inducing high shear and long residence time The starch master batch was prepared in pellet form by extrusion at 190 ° C., and the injection specimen was used to measure the physical properties and biodegradation, and the results are shown in Table 1.

Comparative Example 2

40 parts by weight of corn starch (13% water), 60 parts by weight of polycaprolactone as a biodegradable aliphatic polyester resin, and 15 parts by weight of glycerin as a plasticizer based on 100 parts by weight of the composition was the same as in Comparative Example 1 Injection specimens were prepared, and their physical properties and biodegradability were measured, and the results are shown in Table 1.

Comparative Example 3

40 parts by weight of corn starch (13% moisture), 60 parts by weight of polycaprolactone as a biodegradable aliphatic polyester resin, 15 parts by weight of glycerin as a plasticizer and hexamethylene diisocyanate as a diisocyanate coupling agent based on 100 parts by weight of the composition Except for using 1 part by weight at the same time was prepared in the injection specimen in the same manner as in Comparative Example 1, the physical properties and biodegradability for this was measured, the results are shown in Table 1.

In Table 1, tensile strength and tensile elongation were measured by ASTM D 638, and impact strength was measured by preparing 1/4 inch specimens by ASTM D 256. In addition, the degree of biodegradation was measured after the incubation of the mold on a 5 × 5 × 0.3 cm specimen for 21 days according to the resistance test method of plastic (ASTM G 21-70), and after monitoring the extent to which the mold was covered on the surface of the specimen, Is 0%, 0, 10% or less, 1, 10-30%, 2, 30-60%, 3, 60-100%, and 4 points are given. In Table 1, NB is Izod impact strength. It shows the case that the specimen of 6.4mm thickness does not break during the measurement.

As can be seen from Table 1, the resin composition of the comparative example has a lower tensile strength and impact strength than the resin composition of the embodiment, in the case of Comparative Example 1 it can be seen that the physical properties are not good low elongation and impact strength.

In addition, in order to observe the degree of gelatinization of the starch in the resin composition prepared in Example 1 and Comparative Example 1 and the master batch prepared in Preparation Example 1, the cross section of the injection specimen was photographed with a scanning electron microscope (500 times magnification). 1A, 1B and 1C, respectively. As can be seen in Figures 1a to 1c, starch particles are not gelatinized in the injection specimen of Comparative Example 1 (FIG. 1B) without using a plasticizer and a diisocyanate coupling agent, and the interface with the aliphatic polyester resin is clear. On the other hand, starch masterbatch using a diisocyanate-based coupling agent (FIG. 1C) is difficult to distinguish the interface because the starch and the polyester resin are chemically bonded, and the starch particles are cut in cross section. In the case of the masterbatch using the diisocyanate coupling agent and the injection specimen of Example 1 using the plasticizer (FIG. 1A), the starch in the masterbatch was also uniformly melted by the plasticizer and starch particles were not seen.

As described above, in the biodegradable resin composition of the present invention, since the starch masterbatch excellent in mechanical properties is uniformly distributed in the matrix resin and has excellent compatibility between the starch and the matrix resin, not only the mechanical properties but also the whole resin Is readily biodegradable.

Claims (7)

a) i) 20-90 parts by weight of biodegradable aliphatic polyester resin; ii) 10-80 parts by weight of starch; And iii) 10-100 parts by weight of a starch master batch comprising 0.1-5 parts by weight of a diisocyanate coupling agent based on 100 parts by weight of the biodegradable aliphatic polyester resin of i) and starch of ii); And b) up to 90 parts by weight of a biodegradable aliphatic polyester resin matrix; And c) A biodegradable resin composition comprising 1-20 parts by weight of a plasticizer based on 100 parts by weight of the starch masterbatch of a) and the biodegradable aliphatic polyester resin matrix of b). The biodegradable aliphatic polyester resin and the resin matrix of claim 1 are each independently polytetramethylene succinate, polytetramethylene adipate, polypropiolactone, polycaprolactone, polylactic acid, polyhydroxybutylate- Biodegradable resin composition is selected from the group consisting of a butylate copolymer and mixtures thereof. The starch of claim 1, wherein the starch is pure starch selected from the group consisting of corn starch, rice starch, potato starch, tapioca starch, wheat starch, sweet potato starch and mixtures thereof, or α-starch, acid treated starch, oxidized starch. Biodegradable resin composition which is a modified starch selected from the group consisting of a cationic starch, ester starch, ether starch and mixtures thereof. The biodegradable resin composition of claim 1, wherein the plasticizer is selected from the group consisting of water, glycerin, ethylene glycol, polyethylene glycol, propylene glycol, sorbitol, lactic acid, and mixtures thereof. The diisocyanate-based coupling agent according to claim 1, wherein the diisocyanate-based coupling agent is hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, dicyclohexylmethane 4 , 4'-diisocyanate, naphthalene 1,5-diisocyanate, diphenylmethane 2,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate, phenylene diisocyanate, polymethylene polyphenylene polyisocyanate and Biodegradable resin composition is selected from the group consisting of a mixture thereof. a) i) 20-90 parts by weight of biodegradable aliphatic polyester resin; ii) 10-80 parts by weight of starch; And iii) 0.1-5 parts by weight of a diisocyanate coupling agent with respect to 100 parts by weight of the biodegradable aliphatic polyester resin of i) and ii) by means of a twin screw extruder to produce a starch masterbatch; And b) 10-100 parts by weight of the starch masterbatch of step a), up to 90 parts by weight of the biodegradable aliphatic polyester resin matrix, and 1-20 parts by weight of a plasticizer based on 100 parts by weight of the starch master batch and the resin matrix. The manufacturing method of the biodegradable resin composition containing the process of kneading and extruding using. The method of producing a biodegradable resin composition according to claim 6, wherein the reaction and kneading temperature in the twin screw extruder is 120-210 ° C.