KR19990009615A - Biodegradable aliphatic polyester resin composition containing chitosan and starch - Google Patents

Abstract

According to the present invention, a number average molecular weight of 10,000 to 10,000 formed by polycondensing at least one acid component monomer selected from dicarboxylic acid of Formula 1 or an anhydride thereof and at least one diol component monomer selected from diol of Formula 2 20 to 80 parts by weight of a synthetic biodegradable polymer composed mainly of 60,000 fully biodegradable aliphatic polyesters; Provided is a biodegradable aliphatic polyester resin composition comprising 80 to 20 parts by weight of a natural biodegradable polymer, which is a mixture of at least one of chitin, chitosan and derivatives thereof and at least one mixture of starch or starch derivatives. The film produced using is completely biodegradable and has excellent desired physical properties and can be applied as a general purpose film.

Wherein R and R 'are hydrogen or methyl, n is 2-8

(Wherein m is 2 to 6)

Description

Biodegradable Aliphatic Polyester Resin Composition Containing Chitosan and Starch

The present invention relates to a method for preparing a biodegradable resin, and more particularly, to compounding a fully biodegradable aliphatic polyester prepared by the present applicant Korean Patent Application No. 92-23688 and chitosan and starch which is a biodegradable natural polymer. It relates to an aliphatic polyester resin composition obtained by the improved economic properties and to a method for producing the same.

Currently, polymers commercialized as biodegradable polymers can be divided into chemical synthetic polymers and microbial synthetic polymers, both of which are expensive in terms of price. Especially, PHB and PHB / V, which are biodegradable polymers by microbial synthesis, are 3 to 4 times more expensive than general synthetic plastics such as polybutylene succinate, polylactic acid, and polycaprolactone. It is not suitable for use and is mainly applied for medical use. Chemically synthesized biodegradable polymers are also biodegradable, but they are still 6-7 times more expensive than polyethylene, which is a general-purpose plastic.

Therefore, it would be desirable to lower the price of biodegradable polymers to the price of existing plastics in consideration of business as well as environmental aspects.

In this direction, natural polymers such as starch have been studied, and some commercialized products. Starch is advantageous in terms of price, but workability and physical properties are deteriorated. Chitosan is a natural polymer having a high price but good moldability and physical properties.

Prior arts related to biodegradable polymer materials using starch or chitosan have been disclosed in Japanese Patent Application Laid-open No. Hei 4-185757 for preparing a biodegradable nonwoven fabric by mixing chitosan and cellulose web. A method for producing a biodegradable plastic by mixing chitosan and cellulose fibers as disclosed in Japanese Patent Application Laid-open No. Hei 4-59289 or a chitosan and carboxymethyl cellulose as disclosed in Japanese Patent Application Laid-open No. Hei 4-120142 The method of producing a biodegradable film by mixing is poor in tensile strength, elongation, etc. of the film to be produced, and thus its use as a general-purpose film is not expected.

In addition, as a prior art regarding biodegradable polymer materials using chitosan and starch, Korean Patent Application No. 94-12534 proposes a method of manufacturing a film with a solution of starch and glycerin in chitosan solution. According to this method, although the tensile strength can be obtained excellent film, it is still difficult to apply commercially due to the low elongation of chitosan and starch, and there is still room for improvement because the proposed method has disadvantages of industrial production.

Accordingly, an object of the present invention is to provide a plastic having a low price and excellent physical properties and biodegradability.

According to the present invention for solving the above problems, starch and / or chitosan are compounded in a thermoplastic resin based on a fully biodegradable polyester, which has been developed by the present applicant and filed with Korean Patent Application No. 92-23688. A biodegradable resin composition is provided.

More specifically, according to the present invention, a number average molecular weight of 10,000 is obtained by polycondensing at least one acid component monomer selected from dicarboxylic acid of Formula 1 or an anhydride thereof and at least one diol component monomer selected from diol of Formula 2 20 to 80 parts by weight of a synthetic biodegradable polymer containing, as a main component, a total biodegradable aliphatic polyester of -60,000 and a melt flow index (190 DEG C, 2160 g) of 100 g / 10 minutes or less; A biodegradable aliphatic polyester resin composition is provided which contains 80 to 20 parts by weight of a natural biodegradable polymer which is at least one of chitin, chitosan and derivatives thereof and at least one mixture of starch or starch derivatives.

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

The synthetic biodegradable polymer according to the present invention is the above fully biodegradable aliphatic polyester itself or a polyhydric oxy carboxylic acid such as glycerin, glycidol, pentaerythritol and the like or a polyhydric oxy carboxylic acid or anhydride thereof such as malic acid. It is crosslinked using 0.01 to 5 mol% with respect to 100 mol% of the aliphatic dicarboxylic acid or its anhydride of Formula (1), or the thing couple | bonded with coupling agents, such as a diisocyanate and a diepoxide. Fully biodegradable aliphatic polyesters have a number average molecular weight of 10,000 to 60,000, more preferably 25,000 to 50,000, and a melt flow index (190 DEG C, 2160 g) of 100 g / 10 min or less, more preferably 50 g / 10 min or less. .

In the present composition, the synthetic biodegradable polymer is preferably 20 to 80% by weight based on the total composition. If it is less than 20 parts by weight, it is difficult to achieve desired physical properties.

As the natural biodegradable polymer in the composition, a mixture of one or more of chitin, chitosan and derivatives thereof and one or more of starch or starch derivatives may be used.

Chitin is a substance found in large amounts in the exoskeleton of crustacean arthropods such as crabs and shrimps, and in the cell walls of higher plants such as fungi and seaweeds. The chitosan is synthesized by deacetylation by treating chitin with aqueous sodium hydroxide solution. Derivatives of crosslinked chitin and chitosan can also be used. Examples include crosslinked amino deoxy chitin, crosslinked amino deoxy chitosan, crosslinked carboxy methylchitosan, crosslinked sulfonated chitosan and the like. The amount of chitin, chitosan or derivatives thereof is 1 to 70% by weight based on the total composition.

It is also useful for chitosan to have a viscosity in the range of 50-900 cps and a degree of deacetylation of at least 85%.

Starch can be obtained from plants such as corn, rice, tapioca, potatoes, and grains such as rye, oats, and wheat. Etc. can also be used. Corn starch is the most economical. Also usable starch derivatives include hydroxy ethyl starch, hydroxy propyl starch, acetate starch, oxidized starch, acid treated starch, amphoteric starch, negative starch, compounds having double bonds (maleic anhydride, citraconic anhydride sulfonic benzoic acid, etc.). What crosslinked the starch substituted by) can be used. These starch or starch derivatives are 1 to 90% by weight based on the total composition.

In addition to the above-described polymer components, the present composition may also contain a lubricant, a plasticizer, and the like, which are ordinary additives.

When compounding starch to aliphatic polyester, it is preferable to mix | blend a lubricant, since a workability will fall and a physical property will fall if a lubricant is not used. Examples of lubricants suitable for blending into the composition include aluminum stearate, calcium, magnesium or tin salts; Free acids, unsaturated fatty acid amides, waxes (e.g. Montaniic acid), N, N'-ethylene-bis-stearamids, and the like. The content of such lubricants in the composition is at most 10 parts by weight, preferably 1 to 3 parts by weight, most preferably 1 part by weight per 100 parts by weight of starch.

Examples of plasticizers usable in the composition include glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol; Low molecular weight polyethylene oxide having a molecular weight of 1000 or less such as poly (ethylene glycol), poly (propylene glycol), poly (ethylene-propylene glycol); Glycerin, polyglycerol, sorbitol, mannitol, and the like. Among these, triethylene glycol is particularly preferable. The preferred amount of plasticizer is about 0.1 to 30% by weight, preferably 0.5 to 20% by weight, based on the total weight of all components, including moisture.

The composition of the present invention can be used for the production of injection molded articles such as razors and ballpoint pens or for the production of extruded articles such as blowing films. For example, starch and chitosan are melt-mixed in the above-described fully biodegradable aliphatic polyester in a coaxial twin screw kneader at a cylinder temperature of 100 to 160 ° C, preferably 125 to 140 ° C, and then pellets are prepared. Blowing film can be manufactured using the uniaxial screw extruder with cylinder temperature of 100 degreeC-170 degreeC, Preferably it is 130-150 degreeC.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to Examples.

The blowing film using the fully biodegradable aliphatic polyester and the composition containing the same used in the following Examples and Comparative Examples was prepared by the following method.

Preparation of Fully Biodegradable Aliphatic Polyester Resin A:

In a hot melt condensation reaction tube, 945 g of succinic acid, 281 g of adipic acid, 1.25 kg of 1,4-butanediol and 0.7 g of tetrabutyl titanate as a catalyst are mixed, and the temperature is raised to 200 ° C. in a nitrogen stream to allow water to flow out of the theoretical amount. React until. After the completion of the ester reaction, 0.7 g of tetrabutyl titanate as a catalyst, 2 g of trimethyl phosphate as a stabilizer, 0.2 g of cobalt acetate, and 4 g of dibutyl tin oxide were added in a slurry to 1,4-butanediol, and then the mixture was mixed at 230 DEG C for 10 minutes. After mixing well for a while, the temperature was gradually raised to 250 ° C. while the pressure was 0.3 mmHg, followed by condensation polymerization for 4 hours, and then discharged to obtain a completely biodegradable aliphatic polyester resin A. Melting | fusing point (Tm) of this resin was 90 degreeC, and melt flow index (MI) (190 degreeC, 2160g) was 20g / 10min.

Preparation of Fully Biodegradable Aliphatic Polyester Resin B:

A polyester resin B was prepared by repeating the same procedure as the preparation of the polyester resin A, except that 1.18 kg of succinic acid and 1.26 kg of 1,4 butanediol were used in the hot melt condensation reaction tube. Tm of this resin was 116 degreeC, and MI (190 degreeC, 2160g) was 25g / 10min.

Preparation of Fully Biodegradable Aliphatic Polyester C:

A polyester resin C was prepared by repeating the same procedure as the preparation of the polyester resin A, except that 1180 g of succinic acid and 868 g of ethylene glycol were used in the hot melt condensation reaction tube. Tm of this resin was 100 degreeC, and MI (190 degreeC, 2160g) was 30g / 10min.

Examples 1-8 and Comparative Examples 1-4

To prepare a pellet containing a composition containing the composition shown in Table 1 in the content shown in Table 2 to a Twin-screw Extruder maintained at 120 ~ 140 ℃, kneading, extrusion The prepared pellet was introduced into a single screw extruder having a cylinder of 130 to 150 ° C. and extruded to prepare a blowing film having a thickness of 40 μm.

The prepared film specimens were evaluated for physical properties based on ASTM D638 using a universal testing machine (UTM). The evaluation results are shown in Table 2 below.

PET Starch Chitosan Plasticizer Lubricant Example 1 A Amylose 25% Viscosity 285cps glycerin Calcium stearate Example 2 A Amylose 100% Viscosity 285cps glycerin Calcium stearate Example 3 A Amylose 70% Viscosity 285cps glycerin Calcium stearate Example 4 A Corn starch Viscosity 285cps glycerin Calcium stearate Example 5 A Corn starch Viscosity 285cps glycerin Wax Example 6 A Corn starch Viscosity 285cps PEG Wax Example 7 B Corn starch Viscosity 285cps glycerin Calcium stearate Example 8 C Corn starch Viscosity 285cps glycerin Calcium stearate Comparative Example 1 A - - - - Comparative Example 2 A Corn starch - - - Comparative Example 3 A Amylose 25% Viscosity 285cps - - Comparative Example 4 A Corn starch - - - Comparative Example 5 A - Viscosity 285cps glycerin -

Amylose 25% 5% moisture content, 25% amylose content

* PEG... Polyethylene glycol

PET (part by weight) Starch (parts by weight) Chitosan (part by weight) Plasticizer (phr) Lubricant (phr) Tensile Strength (㎏ / ㎠) % Elongation Example 1 60 30 10 5 One 400 250 Example 2 60 30 10 5 One 450 225 Example 3 60 30 10 5 One 370 270 Example 4 60 20 20 10 One 430 265 Example 5 60 20 20 15 One 420 280 Example 6 50 30 20 15 One 410 250 Example 7 60 30 10 5 One 480 50 Example 8 60 30 10 5 One 450 65 Comparative Example 1 100 - - - - 340 700 Comparative Example 2 60 40 - - - 320 120 Comparative Example 3 60 20 20 - - 350 100 Comparative Example 4 - 50 50 - - Film Molding Defect Comparative Example 5 - 60 40 20 - Film Molding Defect

Reference Example

Chitosan 285cps was dissolved in acetic acid solution corresponding to acetic acid concentration 1.2% to prepare a chitosan solution corresponding to 4% by weight. The chitosan solution was applied to a glass plate and then dried at 70 ° C. to prepare a film composed only of chitosan. The strength of the produced film was 700 kg / cm 2, and the elongation (%) was 2.

The film produced using such a composition is completely biodegradable and has excellent desired physical properties and can be applied as a general purpose film.

Claims (5)

Fully biodegradable aliphatic polys having a number average molecular weight of 10,000 to 60,000 formed by polycondensation of at least one acid component monomer selected from dicarboxylic acid of Formula 1 or an anhydride thereof and at least one diol component monomer selected from diol of Formula 2 20 to 80 parts by weight of a synthetic biodegradable polymer containing ester as a main component; A biodegradable aliphatic polyester resin composition comprising 80 to 20 parts by weight of a natural biodegradable polymer that is a mixture of at least one of chitin, chitosan and derivatives thereof and at least one mixture of starch or starch derivatives. 2. The synthetic biodegradable polymer according to claim 1, wherein the synthetic biodegradable polymer is the above fully biodegradable aliphatic polyester alone or a polyvalent oxy carboxylic acid such as trihydric or higher polyhydric alcohols such as glycerin, glycidol, pentaerythritol and malic acid or A biodegradable aliphatic polyester resin composition, wherein the anhydride is crosslinked using 0.01 to 5 mol% of the aliphatic dicarboxylic acid of formula (1) or 100 mol% of the anhydride thereof. The biodegradable aliphatic polyester resin composition according to claim 1 or 2, wherein the synthetic biodegradable polymer is a coupling agent such as diisocyanate or diepoxide. The biodegradable aliphatic polyester resin composition according to claim 1, which contains up to 10 parts by weight of lubricant per 100 parts by weight of starch. The biodegradable aliphatic polyester resin composition according to claim 1, which contains about 0.1 to 30% by weight of a plasticizer based on the total weight of all the components including water.