KR20000000780A - Process for producing biodegradable copolymer polyester - Google Patents

Abstract

PURPOSE: Two processes for producing a ternary polyester copolymer are provided which is not only still biodegradable but also excellent in mechanical strength, elongation, and impact strength. CONSTITUTION: A first process comprises the steps of: esterification of an aliphatic bivalent carboxylic acid and an aromatic bivalent carboxylic acid with an aliphatic bivalent alcohol and polytetramethylether; adding a catalyst to the product; and polycondensation under high temperature and high vacuum. A second process comprises the steps of: esterification of an aliphatic bivalent carboxylic acid and an aromatic bivalent carboxylic acid; adding polybutyleneterephthalate-polytetramethylene etherglycol copolymer and a catalyst to the product; and polycondensation under high temperature and high vacuum. The final product contains 60-92 mol% of aliphatic ester unit, 3-15 mol% of aromatic ester unit and 2-25 mol% of tetramethyleneether unit.

Description

Biodegradable Copolyester Manufacturing Method

The present invention relates to a method for producing a novel biodegradable terpolymer copolyester with improved impact strength, more specifically, aliphatic divalent carboxylic acid, aromatic divalent carboxylic acid and aliphatic dihydric alcohol together with polytetramethylene ether glycol. After the ester reaction, the catalyst was added, and the catalyst was subjected to condensation polymerization at high temperature and high vacuum, or the ester reaction of aliphatic dihydric carboxylic acid and aliphatic dihydric alcohol was carried out, followed by addition of a polybutylene terephthalate-polytetramethylene ester glycol copolymer with the addition of a catalyst. The present invention relates to a method for producing biodegradable copolyester by condensation polymerization at high temperature and high vacuum.

Recently, as the problem of environmental pollution caused by waste plastics becomes serious, researches on biodegradable polymers have been actively conducted worldwide. As a result, commercialization of biodegradable polymers such as starch-based polymers, cellulose acetate, polyhydroxy butylate, polylactide, polycaprolactone, polybutylene succinate and the like has been achieved. Among these, biodegradable polymers produced by the polycondensation reaction of dihydric alcohols and divalent carboxylic acids, such as polybutylene succinate, are not only excellent in physical properties and processability but also suitable for mass production. Is expected to be. Japanese Patent Application Laid-Open No. 4-189822, Japanese Patent Laid-Open No. 59-213724 discloses a method for producing a pure aliphatic polyester by reacting an aliphatic dihydric carboxylic acid with a dihydric alcohol, and U.S. Patents 5374259 and 5391644 disclose a method for producing aliphatic polyester. A method of using diisocyanates for increasing the molecular weight is disclosed.

In general, aliphatic polyesters are known to have biodegradability, but have low melting points, poor mechanical properties and heat resistance, while aromatic polyesters have good physical properties but are not biodegradable. Taking advantage of these properties, studies have been made to prepare biodegradable random copolymers by stirring aromatic polyesters and aliphatic polyesters with a catalyst to cause typical transesterification reactions (Japanese Patent Laid-Open No. 2-11013, US Patent 42447678, US Patent 5292783). Patent application 90-22052 discloses a method for producing a biodegradable polyester copolymer in which the polymerization degree of aromatic polyester is controlled instead of increasing the content of aromatic polyester in order to improve the physical properties of aliphatic polyester. 027071 discloses a method of copolymerizing aliphatic divalent alcohols and aromatic dihydric alcohols with aliphatic divalent carboxylic acids and aromatic divalent carboxylic acids. In general, biodegradability decreases with increasing aromatic content. However, if the length of the aromatic block is short, as in the case of random copolymers, the aliphatic polyester portion is first decomposed, and the residual aromatic portion is also known to be decomposable because of its relatively low molecular weight. .

However, despite such research efforts, the current production cost of biodegradable polymers is higher than that of general-purpose resins, so the use range is limited to special purposes. In an effort to lower production costs, research has been actively conducted on blends of cheap starch and biodegradable polymers, and the production of starch and biodegradable polymer blends is high and industrially valuable worldwide. However, since starch is insoluble in most cases, it is incompatible with biodegradable polymers, and as a result, the interfacial adhesion with the polymers is degraded, thereby degrading mechanical properties and processability.

In order to increase the compatibility between resin and starch, appropriate lubricants or compatibilizers are used, and researches are being conducted to induce chemical bonding between starch and resin using catalysts or coupling agents. Therefore, it is essential to use a biodegradable polymer having good mechanical strength, elongation and impact strength as the matrix resin. Accordingly, the present inventors have conducted studies for the development of copolyesters having excellent mechanical strength, elongation and impact strength while maintaining biodegradability.

In this study, aliphatic dihydric carboxylic acid, aromatic dihydric carboxylic acid and aliphatic dihydric alcohol were esterified together with polytetramethylene ether glycol having a molecular weight of 1,000, and then a catalyst was added and polycondensation was carried out under high temperature and high vacuum, or aliphatic divalent. Condensation polymerization under high temperature and high vacuum by controlling the amount and timing of addition of polybutylene terephthalate-polytetramethylene ether glycol copolymers having different tetramethylene ether contents after the esterification of carboxylic acid and aliphatic dihydric alcohol. As a result, biodegradable copolyesters having excellent physical properties and processability could be developed. On the contrary, in the case of the copolymer consisting of butylenesuccinate and butylene terephthalate only, the elongation was improved as the content of butylene terephthalate was increased, but the melting point was drastically lowered, not only the crystallization rate was slowed but also the tensile strength was lowered and the impact strength was increased. Not much improved either. In the case of the copolymer consisting of butylene succinate and tetramethylene ether glycol alone, there was no problem in lowering the melting point or crystallization rate, but the impact strength did not improve effectively. The present invention is described in more detail as follows.

The divalent carboxylic acid used in the present invention is an aliphatic divalent carboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid And aromatic divalent carboxylic acids such as 1,4-naphthalenedicarboxylic acid and the like, and it is particularly effective to use succinic acid and adipic acid together with terephthalic acid. Specific examples of aliphatic dihydric alcohols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, and the like. In particular, it is effective to use ethylene glycol and 1,4-butanediol.

In the present invention, the amount of terephthalic acid and polytetramethylene glycol introduced in the initial stage of the ester reaction or the amount of polybutylene terephthalate-polytetramethylene ether glycol copolymer to be added immediately before condensation polymerization is different. It is effective to make aliphatic ester units comprise 60-92 mol% of the total resin, 3-15 mol% of butylene terephthalate units, and 5-25 mol% of tetramethylene ether units. When the ratio of butylene terephthalate units and tetramethylene ether units in the terpolymer copolyester is less than 5 mol% with respect to the whole polymer, it does not help the improvement of physical properties, and when the content is 40 mol% or more, the melting point of the copolymer polyester It is low and not biodegradable, which is undesirable.

Examples of the catalyst used in the present invention include tetra isopropyl titanate, tetra butyl titanate, tetra ethyl titanate, and tetra methyl titanate. The amount of the catalyst used is in the range of 0.01 to 0.5% by weight based on the divalent carboxylic acid. desirable. If the amount of the catalyst is less than 0.01% by weight, the condensation reaction does not proceed effectively, so that a polymer having a sufficient degree of polymerization cannot be obtained. If the amount is more than 0.5% by weight, the reaction rate is increased, but the obtained polymer becomes colored and tends to undergo thermal decomposition. not. During the ester reaction, no catalyst is required, and the catalyst is added at the end of the ester reaction so that the deglycol reaction can proceed effectively in the polycondensation reaction.

As a stabilizer used in the present invention, it is preferable to use a phenolic compound as a primary antioxidant and a sulfur compound as a secondary antioxidant, and the effect as a stabilizer is insufficient at 0.04 to 0.8% by weight or less relative to the divalent carboxylic acid. If it is more than 0.8% by weight, the color of the polymer is deteriorated and mechanical properties are deteriorated. The addition time is not related to the initial or final ester reaction. In the present invention, in addition to the above-mentioned components, UV absorbers, pigments, fluorescent brighteners and the like generally used in the preparation of polyester can be used.

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

Example 1

The reactant was added at a ratio of 0.23 mol of terephthalic acid, 0.36 mol of tetramethylene ether glycol, and 1.2 mol of 1,4-butanediol based on 1 mol of succinic acid, and 0.1 wt% of primary and secondary antioxidants were added to the reactor based on succinic acid, respectively. The ester reaction was carried out over 100 minutes while gradually raising the temperature from room temperature to 200 ° C. The produced water was completely discharged out of the system through the condenser. Then, 0.2 wt% of titanate-based catalyst was added based on succinic acid, mixed well for 10 minutes, and then slowly depressurized to maintain a vacuum of 1 torr or less at a temperature of 250 The condensation reaction was carried out for 3 hours. When the reaction was completed, the vacuum was broken and the polymer was discharged with nitrogen to obtain a final product. The composition and physical properties of the final polymer were evaluated and summarized in Table 1.

The measured values shown in Table 1 are physical property data of the compositions prepared in Examples and Comparative Examples using the following test conditions and methods.

* Content analysis of composition: Analysis of the content of butylenesuccinate, butylene terephthalate, tetramethylene ether units using 300-MH _Z ¹ H NMR.

* Melt index: measured at 130 ℃ and 2160 g load according to ASTM D-1238. The lower the melt index, the higher the degree of polymerization.

* Melting point and heat of melting: measured while heating up at 10 ℃ / min using DSC.

* Tensile Highlight: Measured by ASTM D-638.

* Izod impact strength: Measured by ASTM D-126, 1/4 inch specimen is used.

* Biodegradability: The biodegradability is measured by classifying the degree of mold cover on the surface of 5 × 5 × 0.3 cm specimens after incubating for 60 days according to ASTM G 21-70, the resistance test method of plastic by mold.

Rating 0 One 2 3 4 Mold growth surface area (%) 0 0-10 10-30 30 to 60 60-100

Example 2

Condensation polymerization in the same manner as in Example 1 except that 37 mol% of polybutylene terephthalate-polytetramethylene ether glycol copolymer was added immediately before condensation polymerization instead of terephthalic acid and tetramethylene ether glycol in the initial reaction. It was summarized in Table 1 to evaluate the composition and physical properties of the final polymer.

Examples 3 to 5

Except for changing the input amount of terephthalic acid and tetramethylene ether glycol was condensation polymerization in the same manner as in Example 1 and summarized in Table 1 to evaluate the composition and physical properties of the final polymer.

Comparative Example 1

Except for using only succinic acid and 1,4-butanediol as a reaction, it was condensation-polymerized in the same manner as in Example 1 and summarized in Table 1 to evaluate the composition and physical properties of the final polymer.

Comparative Example 2

Except not adding tetramethylene ether glycol was condensation polymerization in the same manner as in Example 1 and summarized in Table 1 to evaluate the composition and physical properties of the final polymer.

Comparative Example 3

Except that the terephthalic acid was not added, it was condensation-polymerized in the same manner as in Example 1 and summarized in Table 1 to evaluate the composition and physical properties of the final polymer.

Comparative Example 4

Except that the polybutylene terephthalate-polytetramethylene ether glycol copolymer was reduced to 4 mol%, it was condensation-polymerized in the same manner as in Example 2 and summarized in Table 1 to evaluate the composition and physical properties of the final polymer.

Properties and Biodegradability of Various Copolyesters Composition ^a of Copolymerizable Monomer ^a Melt Index (g / 10min) Melting point (℃) Tensile Strength (Kg _f / cm ² ) % Elongation Impact Strength (Kg _f cm / cm) Biodegradability BS (mol%) BT (mol%) BO (mol%) Example 1 62.9 14.5 22.6 2.6 87 130 NB ^b . 53.1 One Example 2 63.4 13.7 22.9 3.6 89 137 N.B. 51.6 One Example 3 65.9 11.0 23.1 3.0 95 156 N.B. 39.9 2 Example 4 75.8 10.8 16.4 4.2 102 210 N.B. 18.9 2 Example 5 90.1 4.5 5.4 3.1 108 284 N.B. 11.7 3 Comparative Example 1 100 0 0 3.5 114 354 300 5.1 4 Comparative Example 2 93.1 6.9 0 3.7 105 263 620 7.8 2 Comparative Example 3 74.1 0 25.9 5.5 110 258 N.B. 9.8 3 Comparative Example 4 96.0 1.6 2.4 3.6 111 312 347 8.6 4

a. BS: butylenesuccinate, BT: butylene terephthalate, BO: butylene oxide (tetramethylene ether) in the copolymer.

b. N.B. : no break, elongation more than 900%.

The present invention provides a copolyester having excellent mechanical strength, elongation and impact strength while maintaining biodegradability.

Claims (23)

In preparing a biodegradable terpolymer copolyester, a) esterifying an aliphatic divalent carboxylic acid and an aromatic divalent carboxylic acid with an aliphatic dihydric alcohol and polytetramethyletherglycol; b) introducing a catalyst into the ester reaction product; And c) condensation polymerization of the mixture containing the catalyst under high temperature, high vacuum Method for producing a copolyester comprising a. The method of claim 1, The aliphatic divalent carboxylic acid is a production method of copolyester selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid. The method of claim 1, Aromatic divalent carboxylic acid is a manufacturing method of co-polyester selected from terephthalic acid, isophthalic acid, 2, 6- naphthalene carboxylic acid, and 1, 4- naphthalenedicarboxylic acid. The method of claim 1, Tertiary co-polyester wherein aliphatic dihydric alcohol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol Method of preparation. The method of claim 1, The manufacturing method of co-polyester whose molecular weight of polytetramethylene ether glycol is 800-1200. The method of claim 1, A method for producing copolyester wherein the catalyst is selected from tetra isopropyl titanate, tetrabutyl titanate, tetraethyl titanate, tetramethyl titanate. The method of claim 6, A method for producing copolyesters in which the amount of the catalyst used is 0.01 to 0.5% by weight based on the divalent carboxylic acid. The method of claim 1, Vacuum in the condensation polymerization step is less than 1 torr. The process according to claim 1, wherein the polymerization temperature in the polycondensation step is 200 to 300 ° C. The method of claim 1, A method for producing copolyester in which a phenol compound and a sulfur compound are added as stabilizers in an ester reaction step. The method of claim 10, A method for producing a copolyester with a phenolic compound and a sulfur compound incorporation amount of 0.04 to 0.8% by weight based on divalent carboxylic acid, respectively. In preparing a biodegradable terpolymer copolyester, a) esterifying aliphatic dihydric carboxylic acid with aliphatic dihydric alcohol; b) injecting a polybutylene terephthalate-polytetramethylene ether glycol copolymer with a catalyst into the ester reaction product; And c) condensation polymerization of the mixture containing the catalyst under high temperature, high vacuum Method for producing a copolyester comprising a. The method of claim 12, The aliphatic divalent carboxylic acid is a production method of copolyester selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid. The method of claim 12, A method for producing a copolyester in which the tetramethylene ether unit in the polybutylene terephthalate-polytetramethylene ether glycol copolymer is 50 to 80 mol% in the copolymer. The method of claim 12, Tertiary co-polyester wherein the aliphatic dihydric alcohol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol Method of preparation. The method of claim 12, A method for producing copolyester wherein the catalyst is selected from tetra isopropyl titanate, tetrabutyl titanate, tetraethyl titanate, tetramethyl titanate. The method of claim 16, A method for producing copolyesters in which the amount of the catalyst used is 0.01 to 0.5% by weight based on the divalent carboxylic acid. The method of claim 12, Vacuum in the condensation polymerization step is less than 1 torr. The method of claim 12, The temperature in the condensation polymerization step is 200 to 300 ℃. The method of claim 1, A method for producing copolyester in which a phenol compound and a sulfur compound are added as stabilizers in an ester reaction step. The method of claim 20, A method for producing a copolyester with a phenolic compound and a sulfur compound incorporation amount of 0.04 to 0.8% by weight based on divalent carboxylic acid, respectively. In biodegradable ternary copolyester comprising three components of aliphatic ester, aromatic ester and tetramethylene ether, Tertiary co-polyester characterized in that 60-92 mol% of aliphatic ester units, 3-15 mol% of aromatic ester units, and 5-25 mol% of tetramethylene ether units. In the blend of biodegradable copolyester and starch, A blend of biodegradable copolyester and starch, wherein the aliphatic ester unit is 60 to 92 mol%, the aromatic ester unit is 3 to 15 mol% and the tetramethylene ether unit is 5 to 25 mol%.