KR100267193B1 - Thermoplastic aliphatic polyester having high molecular weight and biodegradability, and a method for preparation thereof - Google Patents

Abstract

The present invention relates to a high molecular weight thermoplastic aliphatic polyester resin having a biodegradability and a method for preparing the same, and more particularly, it is not only decomposed by microorganisms in soil, but also has improved melting point and mechanical strength as compared to conventional homopolymers. The present invention relates to a high molecular weight thermoplastic aliphatic polyester resin that can be processed into various molded articles and processed articles, and a method of manufacturing the same.

The polyester resin of the present invention has excellent moldability, such as injection and extrusion, and is useful for industrial films such as garbage bags, sheets, plastic containers, and the like. In particular, the polyester resins have excellent elongation, and thus can be used for processed products such as yarns, nonwoven fabrics, composite fibers, and mesh bodies. It can use suitably.

Description

Biodegradable high molecular weight thermoplastic aliphatic polyester resin and its preparation method

The present invention relates to a high molecular weight thermoplastic aliphatic polyester resin having a biodegradability and a method for preparing the same, and more particularly, it is not only decomposed by microorganisms in soil, but also has improved melting point and mechanical strength as compared to conventional homopolymers. The present invention relates to a high molecular weight thermoplastic aliphatic polyester resin that can be processed into various molded articles and processed articles, and a method of manufacturing the same.

Synthetic polymers such as polyolefins and aromatic polyesters are used in large quantities as raw materials for plastic products, which are essential for daily life, but because they are not decomposed in the natural environment, they cause great problems in front of environmental protection due to environmental problems caused by increased consumption. .

Accordingly, although biodegradable aliphatic polyester resins have attracted attention, there are many problems to be solved in terms of price and strength.

For example, polyhydroxybutylate has a high melting temperature and high performance polyester, but a small difference between the melting temperature and the thermal decomposition temperature causes thermal decomposition during molding to cause problems such as deterioration and odor generation. Because it is a high molecular material produced using microorganisms, its productivity is low and its price is high.

In addition, polycaprolactone is a representative biodegradable polyester currently produced industrially, but the melting temperature is only about 60 ° C., and thus is limited in use.

In addition, polymers of hydroxycarboxylic acid are attracting attention as polymers having good biodegradability. In particular, polymers with lactic acid are biocompatible polymers that can be used as bioabsorbable materials, but they are complex, expensive, and hydrolyzed. Due to its fast decomposition rate, it is restricted to use as a general plastic material.

In order to solve the problem regarding manufacture and performance of such aliphatic polyester resin, the polyester resin obtained by the condensation reaction of aliphatic dicarboxylic acid and diol is attracting attention in recent years. They have a structure of the following general formula (1) and are very excellent in biodegradability.

In particular, the thermoplastic polyester resin of the structure of following General formula (2) whose R <^1> , R <^2> is a lower alkyl group occupies most.

These are named polyester resins of (4, 4) structure and (4, 2) structure according to x and y values.

Among these, the polymer of the (4, 2) structure which uses succinic acid as a raw material has a melting range of 70 degreeC or more, and its utilization range is wide. However, the homopolymer has a limitation in that its biodegradability is drastically reduced as the molecular weight is increased to obtain a practically sufficient molecular weight. In fact, it is difficult to obtain a homopolymer having a molecular weight of 100,000 or more. In addition, since the number average molecular weight is less than thousands, it is impossible to obtain mechanical strength that can produce a film or fiber. Thus, in order to prevent the degradation of biodegradability due to the increase in molecular weight, a polyester resin of the following Chemical Formula 3 is also developed by mixing two or more aliphatic dicarboxylic acids, but there is a problem of decolorization and reactivity due to the mixing of dicarboxylic acids. have. In particular, the addition of the dicarboxylic acid having an alkyl group as the side chain is markedly decolorized at large scale. Moreover, it is a state which does not solve the physical property degradation, such as mechanical strength.

In order to improve such deterioration of physical properties in biodegradable polyester resins, Japanese Patent Laid-Open Nos. 4-189822 and 4-189823 disclose aliphatic polyesters having a number average molecular weight of about 150,000 by reaction of aliphatic dicarboxylic acids and glycols. And a method for increasing the molecular weight by crosslinking with diisocyanate is proposed. However, this method has a problem that microgels are generated to degrade polymer quality.

In addition, Japanese Patent Laid-Open No. 6-192374 discloses low molecular weight aliphatic polyesters from aliphatic dicarboxylic acids and glycols with polyhydric alcohols or polyhydric carboxylic acids, and reacts aliphatic polyesters having terminal groups with isocyanate groups. However, a method of obtaining a high molecular weight polymer has been proposed, but the reaction process is increased by two or more steps, and the prepared polyester resin has a large amount of urethane bonds and star type bonds in the molecule, and thus crystallinity and melting point There are problems of falling and degrading biodegradability.

In addition, Japanese Patent Laid-Open Nos. 5-287041 and 5-287042 disclose copolymers having increased number average molecular weight and mechanical strength by copolymerizing three components of aliphatic dicarboxylic acid, glycol and isocyanate, and having a molecular weight distribution. Is widely reported to be suitable for producing molded articles such as films. For the same purpose, Japanese Patent Application Laid-Open No. 5-287068 proposes a four-component copolymer in which 3,3 ', 4,4'-benzophenonetetracarboxylic anhydride is added in addition to the above-mentioned three components, but is biodegradable and environmentally harmful. Has not been reported.

Accordingly, the present inventors have intensively studied to provide a high molecular weight aliphatic polyester resin having sufficient melting point in practical terms and excellent in thermal stability, mechanical strength and processability without degrading biodegradability, and as a result, In the manufacturing method of the polyester resin, by adding and copolymerizing another kind of diol as a third component to the two-component system consisting of dicarboxylic acid and diol, that is, mixing two or more aliphatic diols, the synthesis time is shortened and discoloration is prevented. In addition, the workability is improved and the melting point and mechanical strength are greatly improved compared to the conventional homopolymer, and the present invention has been completed.

Accordingly, it is an object of the present invention to provide a biodegradable high molecular weight thermoplastic aliphatic polyester resin and a method for producing the same, which can be processed into various molded articles and processed articles with improved melting point and mechanical strength compared to conventional homopolymers. .

1 is a ¹³ C-NMR spectrum of the polyester resin obtained in Example 1. FIG.

2 is a ¹ H-NMR spectrum of the polyester resin obtained in Example 2. FIG.

3 is a ¹ H-NMR spectrum of a polyester resin obtained in Example 3. FIG.

4 is a ¹ H-NMR spectrum of the polyester resin obtained in Example 4. FIG.

5 is a DSC curve of the polyester resin obtained in Example 1. FIG.

6 is a DSC curve of the polyester resin obtained in Example 2. FIG.

7 is a DSC curve of the polyester resin obtained in Example 3.

8 is a DSC curve of the polyester resin obtained in Example 4. FIG.

9 is a result of evaluating the biodegradability of the polyester resin obtained in Examples 1-4.

In order to achieve the above object, the method for producing a biodegradable high molecular weight thermoplastic aliphatic polyester resin according to the present invention,

(1) esterifying an aliphatic dicarboxylic acid with an aliphatic diol and at least one aliphatic diol other than the aliphatic diols described above as a third component by dehydration in a nitrogen stream at 160 to 200 ° C; And

(2) After the dehydration reaction is completed, the titanium catalyst is added in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the oligomer obtained in (1), followed by deglycol reaction at 215 to 240 ° C under reduced pressure.

Wherein at least one aliphatic diol as the third component is contained in an amount of 5 to 30 mol% based on 100 mol% of the total aliphatic diols.

The thermoplastic aliphatic polyester resin obtained by the above manufacturing method is a biodegradable resin whose number average molecular weight (Mn) which has a structure of following General formula (I) is 20,000-200,000, and melting | fusing point is 70-120 degreeC.

General formula (Ⅰ)

(In the meal,

R ¹ and R ⁴ are alkyl groups or cycloalkyl groups derived from aliphatic diols,

R ² is an alkyl group or alkenyl group derived from aliphatic dicarboxylic acid,

p means the degree of polymerization required for the number average molecular weight of the thermoplastic aliphatic polyester resin is 20,000 to 200,000,

a 'and c refer to the degree of polymerization of the ester bonding units)

In the polyester resin of the present invention, the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is 1.5 or more, usually 1.8 to 3.5, and the molecular weight distribution is narrow, and the thermal decomposition temperature is 300 ° C. It is higher than

More specifically, the aliphatic diols used in the present invention are ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,10-decanediol, diethylene 1 type selected from the group consisting of glycol and 1,4-cyclohexanedimethanol. Among these, 1,4-butanediol is especially preferable, and the aliphatic diol added as the third component to 1,4-butanediol is preferably 1,6-hexanediol or ethylene glycol. Moreover, it is preferable to copolymerize the aliphatic diol added as a 3rd component in the range of 5-30 mol% with respect to 100 mol% of all aliphatic diols. If it exceeds 30 mol%, the melting point is markedly lowered, which is not preferable.

In addition, the aliphatic dicarboxylic acid used in the present invention is malonic acid (sonic acid), succinic acid (succinic acid), succinic anhydride (maleic acid), isophthalic acid (isophthalic acid), glutaric acid (glutaric acid), Selected from the group consisting of adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid will be. Preferably, the biodegradability of the polyester resin obtained by mixing 2 or more types can be increased. It is preferable to mix | blend 2 or more types and to copolymerize the dicarboxylic acid added in 20-30 mol% with respect to 100 mol% of all the dicarboxylic acids. Also in this case, the aliphatic diol added as the third component is preferably 1,6-hexanediol or ethylene glycol, and is preferably copolymerized in a range of 5 to 15 mol% with respect to 100 mol% of all aliphatic diols.

The thermoplastic aliphatic polyester resin obtained when mixing two kinds of dicarboxylic acids has the structure of the following general formula (II):

General formula (Ⅱ)

In the food,

R ¹ , R ² , and R ⁴ have the same meanings as defined in general formula (I),

R ³ is an alkyl group or alkenyl group derived from aliphatic dicarboxylic acid,

q means the degree of polymerization required for the number average molecular weight of the thermoplastic aliphatic polyester resin is 20,000 to 200,000,

a ", b ', c' and d mean the degree of polymerization of each ester bonding unit)

In the above formula, p, q means a degree of polymerization necessary for the number average molecular weight (Mn) of the thermoplastic aliphatic polyester resin to be 20,000 or more, a ', c, or a ", c' is at least two or more in one molecule It means a polyester polymer compound in which other diols are present.

The present invention uses a titanium-based catalyst as a catalyst in step (2) deglycol reaction, and specific examples are tetraisopropyl titanate, tetra n-butyl titanate, tetraethylene titanate, tetrastearyl titanate, titanium acetoacetate And the like. In addition to the titanium catalyst, zirconium acetoacetate, zinc acetoacetate, or the like may be used.

The high molecular weight thermoplastic polyester resin provided by the present invention has excellent biodegradability and is easily decomposed by microorganisms in soil, as well as less coloring, improved reaction time, and a melting point of 70 ° C. or higher. It is widely used and can be used as a molded product because of its excellent mechanical strength. In particular, compared to the conventional homopolymer by the reaction of dicarboxylic acid and diol, the moldability such as injection and extrusion is excellent, and thus an industrial film or sheet such as a garbage bag It is useful for plastic containers and the like, and in particular, it has excellent elongation and can be suitably used for processed products such as yarns, nonwoven fabrics, composite fibers, and mesh bodies. In addition, it is possible to further improve the physical properties by adding an inorganic filler, it is also possible to mix and use a pigment and the like.

Hereinafter, the configuration and effect of the present invention will be described in more detail with reference to Examples and Test Examples. However, the embodiments are only examples for explaining the configuration of the present invention, and the scope of the present invention is not limited to these embodiments.

<Example 1>

In a 250 mL hard glass four-necked separating flask equipped with a low boiling point compound outlet tube such as a stirrer, a gas inlet tube, a moisture, and a thermometer equipped with a thermometer, 35.4 g of succinic acid, 3.9 g of ethylene glycol, and 22.7 g of 1,4-butanediol After the addition, the temperature was adjusted to 180 to 200 ° C., and esterification reaction by dehydration reaction was carried out in a nitrogen stream.

After the outflow of water was completed, 1.76 × 10 ⁻⁴ mol of tetraisopropyl titanate was added to the resulting oligomer as a deglycol catalyst under a nitrogen atmosphere, and the temperature of the reactor was raised to 215 to 240 ° C. under reduced pressure to give unreacted 1 , 4-butanediol was distilled out.

The number average molecular weight (Mn) of the obtained polyester resin was 78,000, the weight average molecular weight (Mw) was 164,000, and melting | fusing point was 100 degreeC.

<Example 2>

35.4 g of succinic acid, 7.5 g of 1,6-hexanediol and 22.7 g of 1,4-butanediol were added thereto, followed by the same method as in Example 1, to prepare a polyester resin.

The number average molecular weight (Mn) of the obtained polyester resin was 74,000, the weight average molecular weight (Mw) was 147,000, and melting | fusing point was 92 degreeC.

<Example 3>

31.9 g of succinic acid, 4.4 g of adipic acid, 2.0 g of ethylene glycol and 25.6 g of 1,4-butanediol were added thereto, followed by the same method as in Example 1, to prepare a polyester resin.

The number average molecular weight (Mn) of the obtained polyester resin was 77,000, the weight average molecular weight (Mw) was 160,000, and melting | fusing point was 96 degreeC.

<Example 4>

31.9 g of succinic acid, 4.4 g of adipic acid, 3.7 g of 1,6-hexanediol, and 25.6 g of 1,4-butanediol were added thereto, followed by the same method as in Example 1, to prepare a polyester resin.

The number average molecular weight (Mn) of the obtained polyester resin was 77,000, the weight average molecular weight (Mw) was 160,000, and melting | fusing point was 92 degreeC.

Comparative Example 1

35.4 g of succinic acid and 28.4 g of 1,4-butanediol were added to a 250 mL hard glass four-necked separating flask equipped with a low boiling point compound outlet tube such as a stirrer, a gas introduction tube, a moisture, and a sorting capacitor equipped with a thermometer. The temperature was adjusted to 180-200 degreeC, and the esterification reaction by dehydration reaction was carried out in nitrogen stream.

After the outflow of water was completed, 1.83 × 10 ⁻⁴ mol of tetraisopropyl titanate was added to the resulting oligomer as a deglycol catalyst under a nitrogen atmosphere, and the temperature of the reactor was raised to 215 to 240 ° C. under reduced pressure to give unreacted 1 , 4-butanediol was distilled out.

The number average molecular weight (Mn) of the obtained polyester resin was 74,000, the weight average molecular weight (Mw) was 168,900, and melting | fusing point was 115 degreeC.

Comparative Example 2

After 28.3 g of succinic acid, 8.77 g of adipic acid and 28.4 g of 1,4-butanediol were added thereto, the same procedure as in Comparative Example 1 was conducted to prepare a polyester resin.

The number average molecular weight (Mn) of the obtained polyester resin was 70,000, the weight average molecular weight (Mw) was 141,000, and melting | fusing point was 91 degreeC.

Test Example 1 Biodegradability Evaluation

After melt | dissolving the polyester resin obtained in Examples 1-4 at 20 degreeC higher than each melting | fusing point with the heat press, it pressed for 10 minutes by the pressure of 200 kg / cm <2>, and produced the 30-micrometer-thick film, 2cm * 2 The biodegradability was evaluated for 6 weeks under conditions of 30 ° C. and 90% moisture by cutting into a size of cm and embedding in the subleaf soil. The results are shown in FIG.

As a result of observing the appearance change of the film after 6 weeks, in the case of Examples 1 to 4, the surface of the film discolored and uneven spots occurred after 6 weeks compared to the circular film, and it was observed that the film circle was lost.

<Test Example 2> Evaluation of various physical properties

Physical properties of the polyester resins obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured, and the results are shown in Table 1.

Example Tensile Strength (MPa) Elongation (%) Tensile Modulus (MPa) Example 1 35 570 556 Example 2 25 560 435 Example 3 30 570 549 Example 4 27 570 550 Comparative Example 1 50 490 641 Comparative Example 2 26 560 412 Low density polyethylene 16 570 237

The high molecular weight thermoplastic polyester resin provided by the present invention has excellent biodegradability and is easily decomposed by microorganisms in soil, as well as less coloring, improved reaction time, and a melting point of 70 ° C. or higher. It is widely used and can be used as a molded product because of its excellent mechanical strength. In particular, compared to the conventional homopolymer by the reaction of dicarboxylic acid and diol, the moldability such as injection and extrusion is excellent, and thus an industrial film or sheet such as a garbage bag It is useful for plastic containers and the like, and in particular, it has excellent elongation and can be suitably used for processed products such as yarns, nonwoven fabrics, composite fibers, and mesh bodies.

Claims (7)

In the production method of high molecular weight thermoplastic aliphatic polyester resin having biodegradability, (1) esterifying an aliphatic dicarboxylic acid with an aliphatic diol and at least one aliphatic diol other than the aliphatic diols described above as a third component by dehydration in a nitrogen stream at 160 to 200 ° C; And (2) after the dehydration reaction is completed, a titanium catalyst is added in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the oligomer obtained in (1), and deglycol reaction is carried out at 215 to 240 ° C. under reduced pressure. The method for producing a high molecular weight thermoplastic aliphatic polyester resin having biodegradability, wherein at least one aliphatic diol as the third component is contained in an amount of 5 to 30 mol% based on 100 mol% of the total aliphatic diols. The aliphatic diol and the aliphatic diol added as the third component are ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1, 10-decanediol, diethylene glycol and 1,4-cyclohexanedimethanol. The method of claim 2, wherein the aliphatic diol is 1,4-butanediol, and the aliphatic diol added as the third component is 1,6-hexanediol or ethylene glycol. The method of claim 1, wherein the aliphatic dicarboxylic acid is malonic acid, succinic acid, succinic anhydride, maleic acid, isophthalic acid, glutaric acid, Selected from the group consisting of adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid. How to feature. A high molecular weight thermoplastic aliphatic polyester resin produced according to the method of claim 1, wherein the number average molecular weight (Mn) having a structure of the following general formula (I) is 20,000 to 200,000, and has a melting point of 70 to 120 ° C. Thermoplastic aliphatic polyester resin, characterized in that the resin: General formula (Ⅰ) (In the meal, R ¹ and R ⁴ are alkyl groups or cycloalkyl groups derived from aliphatic diols, R ² is an alkyl group or alkenyl group derived from aliphatic dicarboxylic acid, p means the degree of polymerization required for the number average molecular weight of the thermoplastic aliphatic polyester resin is 20,000 to 200,000, a 'and c refer to the degree of polymerization of the ester bonding units) The thermoplastic aliphatic polyester resin according to claim 5, which is prepared by mixing two aliphatic dicarboxylic acids and has a structure of the following general formula (II): General formula (Ⅱ) In the food, R ¹ , R ² , and R ⁴ have the same meanings as defined in general formula (I), R ³ is an alkyl group or alkenyl group derived from aliphatic dicarboxylic acid, q means the degree of polymerization required for the number average molecular weight of the thermoplastic aliphatic polyester resin is 20,000 to 200,000, a ", b ', c' and d mean the degree of polymerization of each ester bonding unit). The thermoplastic aliphatic polyester resin according to claim 6, which is prepared by mixing succinic acid and adipic acid as aliphatic dicarboxylic acid.