CN103980685B - A kind of shock resistance biodegradable polyesters composition and method of making the same - Google Patents

Abstract

The invention discloses an impact-resistant biodegradable polyester composition and a preparation method thereof. It is composed of the following raw materials according to their weight ratios: 40-60 parts of polyhydroxyalkanoate, 20 parts of polybutylene succinate ~40 parts, 10~40 parts of butylene adipate-butylene terephthalate copolymer, 0.01~3 parts of free radical initiator. The impact-resistant biodegradable polyester composition obtained according to the preparation method provided by the present invention has excellent comprehensive properties, outstanding impact resistance, and can be completely biodegraded, which solves the defect that polyhydroxyalkanoate materials become embrittled with storage time, and The preparation method is simple and easy to realize industrialization.

Description

A kind of impact-resistant biodegradable polyester composition and its preparation method

technical field

The invention relates to the technical field of polymer materials, in particular to an impact-resistant biodegradable polyester composition and a preparation method thereof.

Background technique

The extensive use and disposal of traditional polymer materials not only causes the increasing shortage of petroleum resources, but also causes serious damage to the ecological environment. Polyhydroxyalkanoate (PHA) includes 3-hydroxybutyrate homopolymer (P3HB), 3-hydroxybutyrate-3-hydroxyvalerate copolymer (PHBV), 3-hydroxybutyrate-4-hydroxybutyrate copolymer Polyester (P3HB-4HB) and 3-hydroxybutyrate-3-hydroxyhexanoate copolymer (PHBH) are considered to be one of the most promising and competitive materials in the family of biodegradable plastics. Under composting conditions, it can be completely degraded into CO ₂ and H ₂ O without causing any pollution to the environment. PHA is currently mainly synthesized by microorganisms, and its molecular weight is generally between hundreds of thousands to several million. The mechanical and thermal properties of PHA are closely related to the composition and content of its polymerized monomers. 3-hydroxybutyrate homopolymer (P3HB) is an extremely brittle thermoplastic polyester (notched impact strength less than 2kJ/m ² , elongation less than 3%), with a melting point of about 175°C and a glass transition temperature of about At 0°C, the crystal growth rate is fast but the crystal nucleation rate is very slow. When the molar percentage of PHA comonomer (such as 4HB, 3HV, 3HH, etc.) increases, the flexibility of PHA increases, the tensile strength decreases, the melting point decreases, and the crystallization rate decreases. With the increase of the molar percentage of comonomer, the melt processing performance of PHA becomes worse, and the physical aging phenomenon is obvious, which restricts its large-scale application. As a result, PHA is currently mainly used as a rigid plastic or medical material.

Polybutylene succinate (PBS) is a biodegradable petroleum-based ester polymer with good comprehensive mechanical properties, a tensile strength of about 35MPa, a melting point of 112°C, and a glass transition temperature of about - At 30°C, the crystallization rate is faster. In addition, PBS has excellent processability, but its disadvantages are poor impact resistance and low elongation at break.

Butylene adipate-butylene terephthalate (PBAT) is another biodegradable ester polymer. PBAT has good ductility and flexibility, the tensile strength is about 20MPa, the elongation rate is as high as 700%, the melting point is 120°C, and the glass transition temperature is about -30°C. It is often used as a toughening modifier or blended with starch. Various packaging materials.

There have been public reports on the modification of PHA by using PBS or PBAT, but there is no report on the synergistic modification of PHA by using PBS and PBAT at the same time. For example, the Chinese invention patent with the publication number CN101475735A discloses an alloy material comprising polyhydroxyalkanoate, polybutylene succinate, starch, fillers and other additives, although the mechanical properties of the alloy material have been improved to a certain extent , but the impact resistance of the alloy material is still poor, and the melting point of the obtained composition is low (120-132° C.), which limits the application of the material at high temperature. Moreover, due to the poor compatibility between polyhydroxyalkanoate and polybutylene succinate, the alloy material obtained by simple blending has significant microscopic phase separation and unstable microscopic morphology. Publication No. CN101045810A patent of invention discloses a method of modifying PBS or polylactic acid through dynamic crosslinking and toughening PHBV in an internal mixer, which improves the elongation at break of the composition, but the resistance of the obtained composition The impact strength is low, it is difficult to realize continuous production, and it is not conducive to industrialization.

The physical aging phenomenon of polyhydroxyalkanoate is significant, that is, the mechanical properties change with time after molding, and the embrittlement phenomenon is particularly significant, which is specifically manifested as a significant decrease in impact strength over time. This is due to the high purity of polyhydroxyalkanoate, imperfect crystallization during melt processing, and secondary crystallization during storage. This problem seriously restricts the molding, processing and application of polyhydroxyalkanoate, and there is no mature technology to solve it. Most of the mechanical properties reported in existing documents or patents are the mechanical properties within a short period of time (such as 24 hours, CN101045810A) after molding.

Contents of the invention

In view of this, the object of the present invention is to propose an impact-resistant biodegradable polyester composition and a preparation method thereof, so as to obtain a polyester composition with high impact strength, biodegradability, stable mechanical properties during storage, and excellent melt processing properties. thing.

Based on the above purpose, an impact-resistant biodegradable polyester composition provided by the present invention is composed of the following raw materials according to their respective weight ratios: 40-60 parts of polyhydroxyalkanoate, 20-60 parts of polybutylene succinate 40 parts, 10-40 parts of butylene adipate-butylene terephthalate copolymer, 0.01-3 parts of free radical initiator.

Optionally, the polyhydroxyalkanoate is selected from 3 hydroxybutyrate homopolymer, 3 hydroxybutyrate-3 hydroxyvalerate copolymer, 3 hydroxybutyrate-4 hydroxybutyrate copolymer and At least one of 3 hydroxybutyrate-3 hydroxyhexanoate copolymers.

Optionally, the molar content of 3-hydroxyvalerate monomers or 4-hydroxybutyrate monomers or 3-hydroxyhexanoate monomers in the hydroxyalkanoate copolymer is less than 20%.

Optionally, the free radical initiator is selected from bis(tert-butylperoxy) dicumylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexyne, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, per Di-tert-butyl oxide, dicumyl peroxide, tert-butyl peroxybenzoate, lauryl peroxide, dibenzoyl peroxide, tert-butyl peroxy-tert-valerate, diisopropyl peroxydicarbonate At least one of ester, dicyclohexyl peroxydicarbonate and azobisisoheptanonitrile.

The present invention also provides a method for preparing the impact-resistant biodegradable polyester composition, comprising the following steps:

First pass polyhydroxyalkanoate, polybutylene succinate, butylene adipate-butylene terephthalate copolymer, and free radical initiator through a high-speed mixer at room temperature according to the weight ratio Mix uniformly to obtain a premix, and then melt, blend and extrude the above premix through a twin-screw extruder to obtain the impact-resistant biodegradable polyester composition.

Optionally, the temperature of the feeding section of the twin-screw extruder is 20-80°C, and the temperature of other sections is 130-180°C.

Optionally, the screw speed of the twin-screw extruder is 100-450 rpm.

In addition, adding a small amount of functional additives, such as antioxidants, stabilizers, nucleating agents, lubricants, colorants, etc. will not affect the basic mechanical properties of the impact-resistant biodegradable polyester composition, but will also improve its Processability, thermal stability, etc.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific examples.

Example 1

3 hydroxybutyrate homopolymer 50kg, polybutylene succinate 30kg, butylene adipate-butylene terephthalate copolymer 20kg, dicumyl peroxide 0.5kg in Premix uniformly in a high-speed mixer (720 rpm, 5 minutes), then add the above premix into a parallel twin-screw extruder for melt blending and extrusion to obtain an impact-resistant biodegradable polyester composition. The temperatures of the twin-screw extruder from the feeding section to the die section are 40°C, 160°C, 160°C, 160°C, 160°C, 165°C and 160°C respectively, and the screw speed is 160 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Example 2

3 hydroxybutyrate-3 hydroxyvalerate copolymer (3 hydroxyvalerate monomer molar percentage is 2%) 45kg, polybutylene succinate 35kg, butylene adipate- Butylene terephthalate copolymer 20kg, dibenzoyl peroxide 0.4kg are premixed (720 rev/mins, 5 minutes) in high-speed mixer, then above-mentioned premixture is added to parallel twin-screw extrusion The impact-resistant biodegradable polyester composition is obtained by melt blending and extruding in a machine. The temperatures of the twin-screw extruder from the feeding section to the die section are 40°C, 160°C, 160°C, 160°C, 160°C, 165°C and 160°C respectively, and the screw speed is 160 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Example 3

3 hydroxybutyrate-3 hydroxyvalerate copolymer (3 hydroxyvalerate monomer molar percentage is 3%) 50kg, polybutylene succinate 25kg, butylene adipate- Butylene terephthalate copolymer 25kg, dicumyl peroxide 0.6kg are premixed homogeneously (720 rev/mins, 5 minutes) in high-speed mixer, then above-mentioned premixture is added to parallel twin-screw extrusion The impact-resistant biodegradable polyester composition is obtained by melt blending and extruding in a machine. The temperature of the twin-screw extruder from the feeding section to the die section is 40°C, 155°C, 155°C, 160°C, 160°C, 160°C and 165°C, respectively, and the screw speed is 180 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Example 4

3 hydroxybutyrate-4 hydroxybutyrate copolymer (4 hydroxybutyrate monomer molar percentage is 5%) 60kg, polybutylene succinate 25kg, butylene adipate- Butylene terephthalate copolymer 30kg, dicumyl peroxide 1.0kg are premixed (720 rev/mins, 5 minutes) in high-speed mixer, then above-mentioned premixture is added to parallel twin-screw extrusion The impact-resistant biodegradable polyester composition is obtained by melt blending and extruding in a machine. The temperatures of the twin-screw extruder from the feeding section to the die section are 40°C, 150°C, 155°C, 160°C, 160°C, 160°C and 165°C respectively, and the screw speed is 200 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Example 5

30kg of 3 hydroxybutyrate homopolymer, 30kg of 3 hydroxybutyrate-3 hydroxyhexanoate copolymer (3 hydroxyhexanoate monomer molar content is 7%) 18kg, 30kg of polybutylene succinate, Butylene adipate-butylene terephthalate copolymer 25kg, 2,5-dimethyl-2,5-two (tert-butyl peroxy) hexane 0.6kg are pre-prepared in a high-speed mixer Mix evenly (720 rpm, 5 minutes), then add the above premix into a parallel twin-screw extruder to melt, blend and extrude to obtain an impact-resistant biodegradable polyester composition. The temperature of the twin-screw extruder from the feeding section to the die section is 40°C, 150°C, 160°C, 160°C, 160°C, 165°C and 165°C, respectively, and the screw speed is 200 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Example 6

3 hydroxybutyrate homopolymer 40kg, 3 hydroxybutyrate-4 hydroxybutyrate copolymer (4 hydroxybutyrate monomer molar content is 5%) 15kg, polybutylene succinate 30kg, Butylene adipate-butylene terephthalate copolymer 25kg, 2,5-dimethyl-2,5-two (tert-butyl peroxy) hexane 1.0kg are pre-prepared in a high-speed mixer Mix evenly (720 rpm, 5 minutes), then add the above premix into a parallel twin-screw extruder to melt, blend and extrude to obtain an impact-resistant biodegradable polyester composition. The temperature of the twin-screw extruder from the feeding section to the die section is 40°C, 150°C, 160°C, 160°C, 160°C, 165°C and 165°C, respectively, and the screw speed is 300 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Comparative Example 1

Add 50 kg of 3-hydroxybutyrate homopolymer into a parallel twin-screw extruder for melt blending and extrusion to obtain 3-hydroxybutyrate homopolymer extruded material. The temperatures of the twin-screw extruder from the feeding section to the die section are 40°C, 160°C, 160°C, 160°C, 160°C, 165°C and 160°C respectively, and the screw speed is 160 rpm. The 3-hydroxybutyrate homopolymer extruded material was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

Comparative Example 2

3 hydroxybutyrate homopolymer 50kg, polybutylene succinate 30kg, butylene adipate-butylene terephthalate copolymer 20kg are premixed uniformly in high-speed mixer (720 turns / minute, 5 minutes), and then the above-mentioned premixture is added into a parallel twin-screw extruder for melt blending and extruding to obtain an impact-resistant biodegradable polyester composition. The temperatures of the twin-screw extruder from the feeding section to the die section are 40°C, 160°C, 160°C, 160°C, 160°C, 165°C and 160°C respectively, and the screw speed is 160 rpm. The impact-resistant biodegradable polyester composition was injected into dumbbell-shaped specimens for tensile testing and rectangular specimens for notched impact, unnotched impact and bending performance tests using a plastic injection machine according to ASTM standards. The test results are listed in Table 1 and Table 2.

It should be noted that the polyhydroxyalkanoate, polybutylene succinate and butylene adipate-butylene terephthalate copolymer used in the above examples were all heated at 70°C before use. Dry under vacuum for 8 hours. The 3-hydroxybutyrate-4-hydroxybutyrate copolymer used is the product of Metabolix in the United States, and the 3-hydroxybutyrate homopolymer and 3-hydroxybutyrate-3-hydroxyvalerate copolymer used are from Ningbo Tianan Biomaterials Co., Ltd. Co., Ltd. products, the 3-hydroxybutyrate-3-hydroxyhexanoate copolymer used is the product of Kaneka Company in Japan, the polybutylene succinate used is the product of Hangzhou Xinfu Pharmaceutical Group Co., Ltd., butylene adipate Alcohol ester-butylene terephthalate copolymer is a product of BASF, Germany.

Wherein the screw diameter of the twin-screw extruder is 25 millimeters, and the aspect ratio is 41. Among them, the temperature of the plastic injection machine from the feed port to the nozzle is set to 160°C, 170°C, 170°C, 170°C and 175°C respectively, the diameter of the screw of the injection machine is 25 mm, and the aspect ratio is 28.

Wherein tensile strength and elongation at break adopt electronic tensile testing machine (Instron4465) to measure according to ASTMD638 at room temperature, and tensile rate is 50mm/min; Notched impact and unnotched impact adopt the MZ- The 2056 impact testing machine is tested according to ASTMD256; the flexural strength and flexural modulus are measured using an electronic tensile testing machine (Instron4465) at room temperature according to ASTMD790. Wherein, the melting temperature is measured by a differential scanning calorimeter (TA Instruments, USA), and the heating rate is 10° C./min.

The data in Table 1 are measured after the samples are injected and stored at room temperature for 60 days.

Table 1: Performance parameters of compositions in Examples and Comparative Examples

As can be seen from the data in Table 1, compared with the polyhydroxy group of polybutylene succinate, butylene adipate-butylene terephthalate copolymer and free radical initiator not added in comparative example 1 Compared with butyrate, the notched impact strength and unnotched impact strength of the impact-resistant biodegradable polyester composition obtained in Examples 1-6 were increased by more than 20 times and 15 times respectively. Compared with the composition of polyhydroxybutyrate/polybutylene succinate/butylene adipate-butylene terephthalate copolymer without adding free radical initiator in comparative example 2 Compared with that, the notched impact strength and the unnotched impact strength of the impact-resistant biodegradable polyester composition obtained in Examples 1-6 were respectively increased by more than 4.8 times and 2.0 times. Compared with Comparative Example 1 and Comparative Example 2, the flexural modulus of the impact-resistant biodegradable polyester composition obtained in Examples 1-6 was reduced, and the elongation was significantly increased, while other mechanical properties were not significantly affected. These results illustrate that the impact-resistant biodegradable polyester composition obtained by the present invention has excellent comprehensive mechanical properties, especially can improve polyhydroxyalkanoate and polyhydroxyalkanoate/polybutylene succinate/hexane Combined impact resistance and toughness of butylene diacid-butylene terephthalate copolymers. In addition, the impact-resistant biodegradable polyester combinations obtained in Examples 1-6 have higher melting points, indicating that they may be used at higher temperatures.

Table 2: Unnotched impact strength measured under different storage times for injection molded samples of compositions in Examples and Comparative Examples

As can be seen from the data in Table 2, compared with polyhydroxybutyrate in comparative example 1, polyhydroxybutyrate/polybutylene succinate/butylene adipate-terephthalate in comparative example 2 Compared with the composition of butylene glycol formate copolymer, the unnotched impact strength of the impact-resistant biodegradable polyester composition obtained in Examples 1-6 does not change significantly with storage time, indicating that the anti-impact biodegradable polyester composition obtained by the present invention The impact biodegradable polyester composition has no obvious physical aging phenomenon during storage, and its impact resistance has excellent storage stability.

Polyhydroxyalkanoate, polybutylene succinate, and butylene adipate-butylene terephthalate copolymer are three degradable polyesters in terms of mechanical properties, thermal properties (glass transition temperature, Melting point, crystallization temperature, etc.), degradation rate and other aspects have their own advantages and disadvantages. Blending the three can give full play to their respective advantages and make up for their respective deficiencies, so as to obtain new materials with excellent comprehensive properties. However, the polyester components in the impact-resistant biodegradable polyester composition are thermodynamically incompatible during the melt blending process. Therefore, phase separation occurs during the mixing process of the twin-screw extruder, the size of the dispersed phase domain is large, and the cohesive force between the phases is poor, which affects the overall improvement of the comprehensive performance, and the microscopic phase morphology and macroscopic mechanical properties are different. Unstable during storage. In the present invention, three kinds of degradable polyhydroxyalkanoate, polybutylene succinate and butylene adipate-butylene terephthalate copolymer under the mixing action of twin-screw extruder The interfacial grafting reaction between polyesters occurs through free radical initiators, and graft or similar block copolymers are generated in situ as compatibilizers, which not only refines and stabilizes the microscopic phase morphology of the composition, but also promotes the synthesis of polyhydroxyalkanes. The rapid crystallization of the ester improves the mechanical properties of the composition and the stability of the properties during storage, thereby providing a prerequisite for the large-scale production and practical application of the composition. The introduction of free radical initiators does not change the presence of ester linkages in the polyester composition and therefore does not sacrifice polyhydroxyalkanoate, polybutylene succinate and butylene adipate-terephthalate The inherent biodegradability of butylene formate copolymers.

The impact-resistant biodegradable polyester composition provided by the invention can be directly used in extrusion molding, compression molding, injection molding, tape casting or blister molding to prepare various thermoplastic products. In addition, adding a small amount of functional additives, such as antioxidants, stabilizers, nucleating agents, lubricants, colorants, etc. will not affect the basic mechanical properties of the impact-resistant biodegradable polyester composition, but can also improve Its processing performance, thermal stability, etc.

As can be seen from the above, a kind of impact-resistant biodegradable polyester composition and preparation method thereof provided by the present invention have the following beneficial effects:

(1) The free radical initiator triggers the generation of origin at the microscopic interface of polyhydroxyalkanoate, polybutylene succinate, and butylene adipate-butylene terephthalate copolymer. The chemical grafting reaction at the position improves the microscopic interfacial adhesion, which can significantly improve the compatibility of the three polyesters and the stability of the microstructure;

(2) The impact-resistant biodegradable polyester composition obtained according to the preparation method provided by the present invention has the characteristics of good impact toughness, high mechanical strength, high modulus, and excellent heat resistance, and can be directly used for extrusion molding , compression molding, injection molding, calendering and blister molding to prepare various plastic products;

(3) Polybutylene succinate and polybutylene adipate-butylene terephthalate copolymer have a synergistic effect on the modification of polyhydroxyalkanoate, and chemical grafting at the initiator-induced interface Under the premise of the reaction, not only the comprehensive mechanical properties of the composition are significantly improved, but also the crystallization process of the polyhydroxyalkanoate is promoted, thereby significantly improving the impact strength of the impact-resistant degradable polyester composition obtained in the present invention during storage. stability;

(4) The impact-resistant biodegradable polyester composition obtained according to the present invention and its preparation method can be realized on existing polymer material processing equipment, and are low in cost, environmentally friendly, and easy to realize large-scale industrial production.

Those skilled in the art should understand that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention , should be included within the protection scope of the present invention.

Claims (2)

1. An impact-resistant biodegradable polyester composition, characterized in that it is composed of the following raw materials according to their respective weight ratios: 40-60 parts of polyhydroxyalkanoate, 20-40 parts of polybutylene succinate 10-40 parts of butylene adipate-butylene terephthalate copolymer, 0.01-3 parts of dicumyl peroxide; Wherein the polyhydroxyalkanoate is 3 hydroxybutyrate-3 hydroxyvalerate copolymer, 3 hydroxybutyrate-4 hydroxybutyrate copolymer and 3 hydroxybutyrate-3 hydroxyhexanoate obtained by microbial method at least one of ester copolymers; Wherein the molar content of 3-hydroxyvalerate monomers or 4-hydroxybutyrate monomers or 3-hydroxyhexanoate monomers in the hydroxyalkanoate copolymer is lower than 20%. 2. A preparation method for preparing the impact-resistant biodegradable polyester composition according to claim 1, characterized in that, the method comprises the following steps: First polyhydroxyalkanoate copolymer, polybutylene succinate, butylene adipate-butylene terephthalate copolymer, dicumyl peroxide at room temperature according to weight ratio The premix is uniformly mixed with a high-speed mixer to obtain a premix, and then the above premix is melted, blended and extruded by a twin-screw extruder to obtain the impact-resistant biodegradable polyester composition, wherein the temperature of the feeding section is 20 ~ 80°C, the temperature of the other sections is 130-180°C, and the screw speed of the twin-screw extruder is 100-450 rpm.