KR100368533B1 - Manufacturing method of biodegradable aliphatic polyester - Google Patents

Abstract

Aliphatic dihydric carboxylic acids such as succinic acid and adipic acid, aliphatic dihydric alcohols such as ethylene glycol, 1,4-butanediol and branched structures in the main chain of aliphatic polyesters such as 1,2-butanediol and 1,3-butanediol Biodegradable aliphatic polyesters prepared by mixing esterified aliphatic dihydric alcohols, adding titanate-based catalysts, and carrying out condensation polymerization reactions under high temperature and high vacuum have excellent properties and processability. It can be effectively applied to blending products.

Description

Process for producing biodegradable aliphatic polyester

Industrial use field

The present invention relates to a method for producing biodegradable aliphatic polyester, and more particularly, to a method for producing biodegradable aliphatic polyester having excellent physical properties and processability.

Prior art

Recently, as the problem of environmental pollution becomes serious, interest in resource saving, recyclability, biodegradability, environmental impact, product life cycle evaluation, environmental labeling, and composting has increased in the development and use of all products. .

In particular, researches on recycling plastics and disposal problems of waste plastics, along with biodegradable polymers that can be circulated in nature, are actively conducted worldwide.

As a result of active research on biodegradable polymers, biodegradable polymers such as starch-based polymers, cellulose acetate, polyhydroxy butyrate, polylactide, polycaprolactone, polybutylene succinate, etc. have been commercialized and marketed.

Among these, biodegradable aliphatic polyester produced by polycondensation reaction of dihydric alcohol and dihydric carboxylic acid, such as polybutylene succinate, is not only excellent in physical properties and processability but also suitable for mass production, which is the most promising future. It is expected to be a biodegradable polymer.

The biodegradable aliphatic polyester has a large change in physical properties and melting points depending on the number of main chain carbons and the side chains of the dihydric alcohol and the divalent carboxylic acid used in the polycondensation reaction, for example, succinic acid and ethylene glycol or butylene glycol. The polymer made by condensation polymerization has a melting point of 100 ° C or higher and shows properties similar to those of polyethylene.

Japanese Patent Laid-Open No. 4-189822, Japanese Patent Laid-Open No. 59-213724 discloses a method for producing pure aliphatic polyester by reacting aliphatic dicarboxylic acid with aliphatic dihydric alcohol.

US Pat. Nos. 5,374,259 and 5,391,644 disclose methods of using diisocyanates to increase molecular weight in the preparation of aliphatic polyesters.

Korean patent application 94-35594 discloses a method of improving the melt strength of aliphatic polyester by adding hexamethylenediamine with polyhydric alcohol during aliphatic polyester condensation polymerization.

Korean Patent Application 94-29823 discloses a method for producing aliphatic polyester having high molecular weight, high strength and high intrinsic viscosity by adding a tetrahydric alcohol such as pentaerythritol during aliphatic polyester condensation polymerization. However, this method causes a problem that crosslinking of the polymer occurs as the tetrahydric alcohol participates in the reaction, so that the elongation is significantly reduced.

As described above, biodegradable aliphatic polyesters having improved physical properties and melt strength have been developed. However, since their production cost is considerably higher than general-purpose resins, it is difficult to bear the cost problem when used alone.

To solve this problem, a method of blending biodegradable aliphatic polyester with cheap starch has been developed.

However, starch is not compatible with biodegradable aliphatic polyester, so the interfacial adhesion between starch and aliphatic polyester in the blended product is weak, resulting in a significant decrease in the mechanical properties and processability of the blended product.

In order to solve this problem, an appropriate lubricant or compatibilizer is used to improve the compatibility of the starch and the aliphatic polyester, and a method of inducing a chemical bond between the starch and the aliphatic polyester using a catalyst or a coupling agent has been developed.

However, above all, there is a need for a method for producing an aliphatic polyester that can be effectively applied to a blended product with the starch by improving the physical properties and processability of the biodegradable aliphatic polyester itself.

It is an object of the present invention to provide a process for the preparation of biodegradable aliphatic polyesters having excellent physical properties and processability which can be effectively applied to blended products with starch.

In order to achieve the above object of the present invention, the present invention provides an aliphatic dihydric alcohol that can form a branched structure (branch) in the main chain (aliphatic dihydric carboxylic acid, aliphatic dihydric alcohol and aliphatic polyester) The present invention provides a method for producing a biodegradable aliphatic polyester by mixing and reacting an ester followed by a polycondensation reaction.

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

As the aliphatic divalent carboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid or sebacic acid may be used, and succinic acid alone or a mixture of succinic acid and adipic acid may be used.

The aliphatic dihydric alcohol may be ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol or 1,4-cyclohexane Dimethanol can be used, with preference being given to ethylene glycol or 1,4-butanediol.

Aliphatic dihydric alcohols capable of forming the branched structure include 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4 -Pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,2-octanediol, 1,3-octanediol, 1,4- Octanediol, 1,5-octanediol, 1,6-octanediol, and 1,7-octanediol can be used, and 1,2-butanediol and 1,2-hexanediol are preferably used alone or in combination.

Here, it is preferable that the usage-amount of the aliphatic dihydric alcohol which can form the said branched structure is 1-30 mol% of the said aliphatic dihydric carboxylic acid. If the amount is 1 mol% or less, the physical properties of the aliphatic polyester cannot be sufficiently improved, and if the amount is more than 30 mol%, the melting point of the aliphatic polyester is lowered, resulting in poor crystallinity.

It is preferable to add a stabilizer during the ester reaction, wherein the stabilizer input time can be any time at the beginning or end of the ester reaction.

As a stabilizer, it is preferable to use together the phenol type compound which is a primary antioxidant, and the sulfur type compound which is a secondary antioxidant. At this time, it is preferable to use the primary antioxidant and the secondary antioxidant at 0.04-0.8% by weight of the aliphatic divalent carboxylic acid, respectively. When the stabilizer is used at less than 0.04% by weight, the effect as a stabilizer cannot be sufficiently exhibited, and when the stabilizer is used at more than 0.8% by weight, the color of the aliphatic polyester is deteriorated and mechanical properties are degraded.

In addition, at the end of the ester reaction, it is preferable to add a catalyst for effectively proceeding the deglycol reaction in the polycondensation reaction.

Tetra isopropyl titanate, tetra butyl titanate, tetra ethyl titanate or tetra methyl titanate can be used as the catalyst.

It is preferable that the usage-amount of the said catalyst is 0.01-0.5 weight% of the said aliphatic divalent carboxylic acid. If the amount of the catalyst is less than 0.01% by weight, the polycondensation reaction cannot proceed effectively, so that a polymer having sufficient degree of polymerization cannot be obtained. If the amount of the catalyst is more than 0.5% by weight, the rate of the polycondensation reaction is increased, but the produced polymer It is not preferable because it is colored and pyrolysis proceeds.

The polycondensation reaction is carried out under a high temperature and high vacuum using the catalyst, specifically, it is preferably carried out at a temperature of 200-300 ° C. and a vacuum degree of 1 torr or less. When it is out of the said temperature and atmospheric pressure conditions, a polycondensation reaction cannot be performed preferably.

In the production of the aliphatic polyester of the present invention, it may be prepared by including a UV absorber, a pigment, a fluorescent brightener, and the like used in the production of ordinary polyester.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

Example 1

A reactant containing 6 moles of succinic acid, 6.48 moles of 1,4-butanediol and 0.72 moles of 1,2-butanediol was placed in a 2 L reactor, and the first and second antioxidants each weighed 0.1 weight of the aliphatic divalent carboxylic acid. After the addition by%, the ester reaction was carried out over 100 minutes while gradually increasing the temperature from room temperature to 200 ° C. At this time, the produced water was completely discharged out of the system through the condenser. Then, 0.2 wt% of the titanate-based catalyst was added based on succinic acid, mixed well for 10 minutes, and then slowly depressurized to maintain the vacuum at 1 Torr or lower. It was raised to 250 ℃ and proceeded the condensation polymerization reaction for 3 hours. After the reaction was completed, the vacuum was released and the polymer was discharged with nitrogen to obtain a final product. The composition and physical properties of the final polymer were evaluated and shown in Table 2.

At this time, the melt index was measured at a load of 2160g at 130 ° C according to ASTM D-1238.

Melting | fusing point was measured, heating up at 10 degree-C / min using DSC.

Tensile strength and elongation were measured by ASTM D-638.

Flexural strength and flexural modulus were measured by ASTM D-790.

Izod impact strength was measured by ASTM S-256, and 1/4 inch specimens were used.

Biodegradability was determined by incubating the mold on 5 × 5 × 0.3cm specimens for 40 days in accordance with ASTM 21-70, a test for the resistance of plastics by mold, to determine the degree of mold cover on the surface as shown in Table 1.

TABLE 1

Example 2

The reaction was carried out in the same manner as in Example 1, except that a reactant having a ratio of 5.4 mol of succinic acid, 0.6 mol of adipic acid, 6.48 mol of 1,4-butanediol, and 0.72 mol of 1,2-butanediol was used.

Example 3

The reaction was carried out in the same manner as in Example 1, except that a reactant containing 6 mol of succinic acid, 6.98 mol of 1,4-butanediol, and 0.22 mol of 1,2-hexanediol was used.

Example 4

The reaction was carried out in the same manner as in Example 1, except that a reactant in a ratio of 4.8 mol of succinic acid, 1.2 mol of adipic acid, 6.98 mol of 1,4-butanediol, and 0.22 mol of 1,2-hexanediol was used.

Example 5

The procedure was carried out in the same manner as in Example 1, except that 4.8 mol of succinic acid, 1.2 mol of adipic acid, 6.73 mol of 1,4-butanediol, 0.36 mol of 1,2-butanediol, and 0.11 mol of 1,2-butanediol were used. It was.

Comparative Example 1

The reaction was carried out in the same manner as in Example 1, except that a reactant having 6 mol of succinic acid and 7.2 mol of 1,4-butanediol was used.

Comparative Example 2

The reaction was carried out in the same manner as in Example 1, except that 5.4 moles of succinic acid, 0.6 moles of adipic acid, and 7.2 moles of 1,4-butanediol were used.

Comparative Example 3

The reaction was carried out in the same manner as in Example 1, except that 4.8 moles of succinic acid, 1.2 moles of adipic acid, and 7.2 moles of 1,4-butanediol were used.

Comparative Example 4

The same procedure as in Example 1 was carried out except that 6 mol of succinic acid, 7.2 mol of 1,4-butanediol, and 0.05 mol of glycerin were used.

TABLE 2

As shown in Table 1, it can be seen that in Example 1-5, the biodegradability is generally superior to Comparative Examples 1-4, but the physical properties and workability are evenly excellent.

The biodegradable aliphatic polyester of the present invention is excellent in physical properties and processability, and is not only effectively applicable to blending products with starch, but also suitable for mass production.

Claims (5)

a) i) aliphatic divalent carboxylic acid; ii) aliphatic dihydric alcohols; And iii) aliphatic dihydric alcohols capable of forming a branched structure in the backbone of the aliphatic polyester Mixing and reacting the esters; And b) polycondensation of the esterified mixture of step a) In the method for producing a biodegradable aliphatic polyester comprising: Of a biodegradable aliphatic polyester in which an aliphatic dihydric alcohol capable of forming a branched structure in the main chain of the aliphatic polyester of a) iii) is mixed at 1 to 30 mol% of the aliphatic divalent carboxylic acid of a) i). Manufacturing method. The method of claim 1, wherein the aliphatic dicarboxylic acid is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, and sebacic acid. The method of claim 1, wherein the aliphatic dihydric alcohol is ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol and 1 A method for producing a biodegradable aliphatic polyester selected from the group consisting of, 4-cyclohexanedimethanol. The method of claim 1, wherein the aliphatic dihydric alcohol capable of forming a branched structure is 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,3-pentane Diol, 1,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,2-octanediol, 1,3-octanediol , 1,4-octanediol, 1,5-octanediol, 1,6-octanediol and 1,7-octanediol. The method of claim 1. The polycondensation reaction is carried out using a catalyst selected from the group consisting of tetra isopropyl titanate, tetra butyl titanate, tetra ethyl titanate and tetra methyl titanate, at a temperature of 200-300 ° C. and below 1 torr. A method for producing a biodegradable aliphatic polyester, which is carried out under vacuum.