Fully-degradable polymer composite material for tableware and preparation method of fully-degradable polymer composite material

Abstract

The invention provides a full-degradable polymer composite material for tableware and a preparation method of the full-degradable polymer composite material, and belongs to the technical field of polymer materials. According to the invention, amylose corn starch, hydrophobic modified corn starch, cassava acetylated distarch phosphate, a polylactic acid-poly (butylene succinate) interpenetrating network structure material, a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, stearic acid modified micron titanium dioxide, chitosan quaternary ammonium salt and a composite plasticizer are adopted according to a specific ratio; the fully-degradable polymer composite material is obtained by compounding the composite heat stabilizer and stearic acid, has controllable and good biodegradability and good mechanical properties, enhances heat stability, improves processability, makes all the components easier to mix uniformly, facilitates molding processing of the material, and improves production efficiency and product quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a fully biodegradable polymer composite material for tableware and a preparation method thereof. Background Art

[0002] In the past few decades, traditional plastic tableware has been widely used in the catering industry due to its low cost, convenient production, stable performance and other characteristics. However, with the improvement of global environmental awareness and the increasing severity of plastic pollution problems, the environmental hazards brought by traditional plastic tableware have gradually become the focus of social attention.

[0003] Traditional plastic tableware is mainly made of non-degradable polymer materials such as polyethylene (PE), polypropylene (PP), polystyrene (PS), etc. These materials are difficult to decompose in the natural environment, and their degradation period often reaches hundreds or even thousands of years. After a large number of waste plastic tableware are discarded at will, they will not only cause "white pollution", damage the soil structure, affect the air permeability and water retention of the soil, hinder the growth and development of crop roots, and lead to crop yield reduction; but also pose a serious threat to the water ecosystem. Plastic garbage floats in rivers, lakes and oceans, is eaten by aquatic organisms, causing intestinal blockage, malnutrition and even death, and destroying the balance of the entire aquatic ecological chain. In addition, traditional plastic tableware consumes a large amount of non-renewable resources such as petroleum in the production process. With the increasing depletion of petroleum resources, it has become extremely urgent to find sustainable alternative materials.

[0004] To solve the environmental problems brought by traditional plastic tableware, degradable materials have emerged. Degradable materials refer to a class of materials that can undergo chemical structure changes within a certain period of time under specific environmental conditions, such as the action of microorganisms, light, moisture, etc., and finally decompose into small molecule substances and return to the natural environment. At present, the degradable materials applied to the tableware field mainly include biodegradable materials and photodegradable materials.

[0005] Biodegradable materials use the metabolic action of microorganisms to decompose the materials into harmless substances such as carbon dioxide, water and biomass. Common biodegradable materials include polylactic acid, polyhydroxyalkanoates (PHA), starch-based materials, etc. Polylactic acid is made by fermenting starch or sugars extracted from renewable plant resources (such as corn, sugarcane, etc.). It has good biocompatibility and can be made into various tableware, such as lunch boxes, dinner plates, etc. However, polylactic acid tableware is brittle in a dry environment and easy to break. When in contact with high-temperature food or hot water, polylactic acid tableware may shrink, deform or even leak. Polyhydroxyalkanoates are a class of polyesters synthesized by microorganisms under specific conditions, with excellent biodegradability and biocompatibility, but their high production cost limits large-scale application. Starch-based materials are made with starch as the main raw material and other additives. They have a low cost, but have problems such as poor mechanical properties and water resistance.

[0006] Photodegradable materials are made by adding photosensitizers to plastics, which undergo a photochemical reaction under ultraviolet light irradiation and thus decompose. However, the degradation process of photodegradable materials is greatly affected by light conditions. It is difficult to effectively degrade indoors or in environments with insufficient light, and the degradation is incomplete, still producing small molecule fragments, which pose a potential hazard to the environment.

[0007] Therefore, it is necessary to develop more suitable materials that can achieve good use performance by improving the material formula and production process, and can also achieve controllable degradation to meet the dual requirements of tableware for performance and environmental protection. Summary of the Invention

[0008] Aiming at the problems existing in the existing high molecular degradation materials for tableware, such as brittle fracture of polylactic acid, softening of starch, insufficient mechanical strength, poor heat and water resistance, and limited degradation conditions, the present invention provides a completely degradable high molecular composite material for tableware and its preparation method. The composite is made by combining specific proportions of linear corn starch, hydrophobically modified corn starch, tapioca acetylated distarch phosphate, poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, stearic acid modified micron titanium dioxide, chitosan quaternary ammonium salt, composite plasticizer, composite heat stabilizer, etc., to obtain a completely degradable high molecular composite material with controllable and good biodegradability, good mechanical properties, enhanced thermal stability, improved processing performance, making each component easier to mix evenly, facilitating the forming process of the material, and improving production efficiency and product quality. The specific technical solution is as follows:

[0009] A completely degradable high molecular composite material for tableware, comprising the following raw materials in parts by mass: 3 to 5 parts of linear corn starch, 10 to 15 parts of hydrophobically modified corn starch, 10 to 15 parts of tapioca acetylated distarch phosphate, 30 to 40 parts of poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, 8 to 10 parts of copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 3 to 5 parts of polycaprolactone, 1 to 2 parts of stearic acid modified micron titanium dioxide, 2 to 4 parts of chitosan quaternary ammonium salt, 5 to 8 parts of composite plasticizer, 3 to 5 parts of composite heat stabilizer, and 0.3 to 1 part of stearic acid.

[0010] Among the above raw materials, the preparation method of the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material includes: mixing poly(lactic acid), poly(butylene succinate) and rosmarinic acid evenly at 80°C to 90°C, then extruding with a twin-screw extruder, air-cooling and drawing into strips, and pelletizing to obtain the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material.

[0011] In the preparation method of the above-mentioned polylactic acid-poly(butylene succinate) interpenetrating network structure material, the mass ratio of polylactic acid to poly(butylene succinate) is (1-1.5):1; the dosage of rosmarinic acid is 3%-5% of the total mass of polylactic acid and poly(butylene succinate); the extrusion temperature of the twin-screw extruder is 165°C-180°C, and the screw speed is 250 r / min-300 r / min. The materials are fully melted and kneaded under high temperature and the shearing action of the screw to form an interpenetrating network structure.

[0012] In the above raw materials, the preparation method of stearic acid-modified micron titanium dioxide includes: dissolving stearic acid in ethanol, then adding micron titanium dioxide, ultrasonically dispersing evenly, stirring and reacting, evaporating and recovering ethanol, taking the solid and drying it in vacuum, and dispersing it to obtain stearic acid-modified micron titanium dioxide.

[0013] In the preparation method of the above stearic acid-modified micron titanium dioxide, the mass ratio of micron titanium dioxide to stearic acid is 10:(1-1.5); the dosage of ethanol is 100-150 times the mass of stearic acid, and the temperature of ethanol is 60°C-65°C; the stirring reaction time is 1 h-2 h, and the stirring reaction speed is 300 r / min-500 r / min; the vacuum drying temperature is 40°C-50°C, and vacuum drying is carried out until constant weight.

[0014] In the above raw materials, the composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxidized soybean oil of (3-4):(1-1.5).

[0015] In the above raw materials, the composite heat stabilizer is a composite plasticizer with a mass ratio of iron pyrophosphate to zinc stearate of (2-3):(1-1.5).

[0016] The preparation method of the above-mentioned fully biodegradable polymer composite material for tableware includes the following steps:

[0017] S1: By mass, uniformly mix linear corn starch, hydrophobically modified corn starch and tapioca acetylated distarch phosphate at 70°C-80°C, then add stearic acid-modified micron titanium dioxide and mix evenly; then add the polylactic acid-poly(butylene succinate) interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt, and mix evenly; then add the composite plasticizer, the composite heat stabilizer and stearic acid, and mix evenly at 60°C-70°C to obtain a base material;

[0018] S2: Add the base material to a twin-screw extruder for melt blending and extrusion, air-cooled draw bar, and pelletize to obtain the pellets of the fully biodegradable polymer composite material.

[0019] In the above preparation method, linear corn starch, hydrophobically modified corn starch and tapioca acetylated distarch phosphate are pre-dried; the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and quaternary ammonium chitosan are pre-crushed and dried.

[0020] In the above preparation method, the extrusion temperature of the twin-screw extruder is 160°C to 170°C, and the screw speed is 250 r / min to 300 r / min.

[0021] A fully biodegradable polymer composite material for tableware and its preparation method according to the present invention have the following beneficial effects:

[0022] First, a large number of hydroxyl groups are contained inside the linear corn starch. These hydroxyl groups can form extensive hydrogen bonds between molecules, endowing the material with a certain cohesion, which helps to improve the overall strength and stability of the material. However, the linear corn starch has strong hydrophilicity. When used alone, the material is prone to moisture absorption, resulting in a decline in performance. The hydrophobically modified corn starch significantly improves its hydrophilicity on the basis of retaining some of the original characteristics of the starch by hydrophobically modifying the corn starch. It can reduce the overall moisture absorption of the material, improve the dimensional stability and water resistance of the material in a humid environment, and avoid problems such as softening and strength reduction caused by water absorption. Tapioca acetylated distarch phosphate has good film-forming properties and flexibility, and can form a continuous film structure inside the material, increasing the flexibility of the material and making it not easily brittle when subjected to external forces.

[0023] The linear corn starch provides the basis for cohesion and strength, and can reduce the water absorption of the composite material to a certain extent. The hydrophobically modified corn starch improves the water resistance, and tapioca acetylated distarch phosphate increases the flexibility. The three cooperate with each other to achieve a better balance among the strength, flexibility and water resistance of the material, overcome the limitations of the performance of single starch-based materials, and significantly improve the comprehensive performance.

[0024] II. Preparation of Interpenetrating Network Structure Materials from Polylactic Acid (PLA) and Polybutylene Succinate (PBS): PLA has good mechanical properties and processability, but is relatively brittle; PBS has good flexibility and biodegradability, but relatively low strength. By forming an interpenetrating network structure from them, complementary properties can be achieved. The molecular structure of rosmarinic acid contains multiple phenolic hydroxyl groups, and these phenolic hydroxyl groups have strong hydrogen bond-forming ability. During the preparation of the polylactic acid-polybutylene succinate interpenetrating network structure material, the phenolic hydroxyl groups of rosmarinic acid can form a large number of hydrogen bonds with carbonyl, hydroxyl and other groups on the molecular chains of PLA and PBS. On the one hand, these hydrogen bonds promote the interpenetration and entanglement of the molecular chains of PLA and PBS, enabling the two polymers to be more uniformly mixed and form a more stable and perfect interpenetrating network structure; on the other hand, the presence of hydrogen bonds enhances the intermolecular interaction force, thereby improving the mechanical properties of the material; at the same time, it also improves the thermal stability of the material, enabling the material to maintain good properties at higher temperatures, resist high-temperature oxidation, and reduce the occurrence of thermal degradation.

[0025] III. Polylactic Acid-Polybutylene Succinate Interpenetrating Network Structure Material: It combines the high strength and easy processability of PLA with the flexibility and biodegradability of PBS, and has good mechanical properties and processability, capable of meeting the requirements for strength and shape retention during the forming and use of tableware. Copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV): PHBV is a polymer with excellent biocompatibility and biodegradability, and can be decomposed by microorganisms into small molecules such as water and carbon dioxide in the natural environment. However, using PHBV alone is difficult to meet the requirements for strength and durability of tableware. In the present invention, the two are used in combination in a certain proportion. The polylactic acid-polybutylene succinate interpenetrating network structure material provides good mechanical strength and processability, ensuring the strength and stability of the tableware during use; PHBV endows the material with excellent biodegradability, enabling the tableware to be rapidly degraded in the natural environment after use, reducing environmental pollution. The two work synergistically to achieve the dual advantages of performance and environmental protection.

[0026] IV. The polycaprolactone (PCL) molecular chain has high flexibility and can play a plasticizing role in the composite material, reducing the intermolecular forces between other polymer molecular chains, improving the overall flexibility of the material, thereby enhancing the processing performance of the material, making it easier to form during the processing, and at the same time improving the mechanical properties of the material during use and reducing the risk of rupture caused by brittleness. PCL has good compatibility with a variety of polymers and can be intermixed at the molecular level with other components in the composite material, including poly(lactic acid)-poly(butylene succinate) interpenetrating network structure materials, starch substances, etc. This compatibility can reduce the interfacial tension between components, promote the uniform dispersion of components, form a more stable composite material system, avoid performance defects caused by uneven component dispersion, and thus improve the overall performance of the material.

[0027] V. Micron titanium dioxide itself has high hardness and good ultraviolet shielding performance, which can improve the mechanical strength of the material. However, due to its hydrophilic surface, its compatibility with organic polymer materials is poor, and it is difficult to be uniformly dispersed in the polymer matrix and is prone to agglomeration. This not only fails to fully exert its role in enhancing and shielding ultraviolet rays, but instead becomes a stress concentration point inside the material, reducing the performance of the material. In the present invention, micron titanium dioxide is surface-modified with stearic acid. The long-chain alkyl part in the stearic acid molecule has a similar structure to the organic polymer material and can have a good affinity with the polymer matrix; at the same time, the coating of stearic acid introduces hydrophobic groups on the surface of micron titanium dioxide, greatly improving its compatibility with organic polymer materials. Therefore, the stearic acid-modified micron titanium dioxide can be more uniformly dispersed in the polymer matrix, fully exert its enhancing effect, and effectively improve the mechanical properties of the material; and can better play the role of shielding ultraviolet rays.

[0028] VI. Ferric pyrophosphate has good thermal stability and antioxidant properties. In a high-temperature environment, it can capture free radicals generated during the degradation of the material and inhibit the oxidative degradation reaction of the material, thereby stabilizing the chemical structure of the material and preventing the performance deterioration of the material due to thermal oxidation, including yellowing and embrittlement. In addition to having a certain thermal stabilization effect, zinc stearate also has good lubricity. During the processing of the material, zinc stearate can reduce the friction coefficient between the material and the processing equipment and between the molecules inside the material, prevent local overheating of the material caused by frictional heat generation, and thus avoid the occurrence of thermal degradation. At the same time, the lubricating film formed by zinc stearate in the material can also improve the fluidity of the material and enhance the processing performance.

[0029] Ferric pyrophosphate mainly improves the thermal stability of the material from the perspective of inhibiting oxidative degradation, while zinc stearate ensures the thermal stability of the material during processing by reducing friction and improving processing performance. According to the characteristics of each component of the material, the present invention makes the two cooperate in a certain proportion, and they act synergistically in different aspects to comprehensively improve the thermal stability of the material, so that the material can better maintain stable performance during processing and use.

[0030] VII. Tributyl citrate can be inserted between polymer molecular chains, weaken the intermolecular interaction force, increase the mobility of molecular chains, thereby significantly improving the flexibility and plasticity of the material, making it easy to process and form, and meeting the processing requirements of the complex shape of tableware. The molecular structure of epoxidized soybean oil contains epoxy groups, and these epoxy groups can interact with polymer molecular chains to further enhance the cohesion and stability of the material. At the same time, epoxidized soybean oil can improve the water resistance of the material.

[0031] Tributyl citrate is mainly responsible for improving the flexibility and plasticity of the material. While epoxidized soybean oil is used as an auxiliary plasticizer, it enhances the water resistance and other properties of the material. The two are used in combination to achieve the synergy of plasticization effect and the improvement of other properties, making the material not only have good processing performance and flexibility, but also have good comprehensive properties such as water resistance, meeting the performance requirements of tableware in different use environments.

[0032] In summary, using the fully biodegradable polymer composite material of the present invention to prepare tableware has controllable and good biodegradability, good mechanical properties, enhanced thermal stability, improved processing performance, making each component easier to mix evenly, facilitating the forming processing of the material, and improving production efficiency and product quality. Detailed implementation mode

[0033] The following further illustrates the present invention in combination with specific implementation cases, but the present invention is not limited to these embodiments.

[0034] Example 1

[0035] A fully biodegradable polymer composite material for tableware, comprising the following raw materials in parts by mass: 4 parts of linear corn starch, 12 parts of hydrophobically modified corn starch, 13 parts of tapioca acetylated distarch phosphate, 35 parts of a poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, 9 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 4 parts of polycaprolactone, 1.5 parts of stearic acid-modified micron titanium dioxide, 3 parts of chitosan quaternary ammonium salt, 7 parts of a composite plasticizer, 4 parts of a composite heat stabilizer, and 0.6 part of stearic acid.

[0036] Among them, the preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: according to the mass ratio of polylactic acid to polybutylene succinate being 1.3:1 and the dosage of rosmarinic acid being 4% of the total mass of polylactic acid and polybutylene succinate, polylactic acid, polybutylene succinate and rosmarinic acid are mixed evenly at 85°C, and then extruded by a twin-screw extruder. The extrusion temperature is 175°C, the screw speed is 280 r / min, and the materials are fully melted and kneaded under the action of high temperature and the shear of the screw to form an interpenetrating network structure; air-cooled and drawn into strips, and pelletized to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0037] Among them, the preparation method of the stearic acid-modified micron titanium dioxide includes: according to the mass ratio of micron titanium dioxide to stearic acid being 10:1.3, stearic acid is dissolved in ethanol at 62°C which is 130 times the mass of stearic acid, and then micron titanium dioxide is added, and ultrasonic dispersion is carried out evenly at 40 KHz, and stirring reaction is carried out at 400 r / min for 1.5 h, ethanol is evaporated and recovered, and the solid is vacuum dried at 45°C to constant weight and then dispersed to obtain the stearic acid-modified micron titanium dioxide.

[0038] Among them, the composite plasticizer is a composite plasticizer with the mass ratio of tributyl citrate to epoxidized soybean oil being 3.5:1.2.

[0039] Among them, the composite heat stabilizer is a composite plasticizer with the mass ratio of iron pyrophosphate to zinc stearate being 2.5:1.2.

[0040] The preparation method of the above-mentioned fully biodegradable polymer composite material for tableware includes the following steps:

[0041] The linear corn starch, the hydrophobic modified corn starch and the tapioca acetylated distarch phosphate are respectively pre-dried at 75°C for 18 h and reserved; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, the polycaprolactone and the chitosan quaternary ammonium salt are respectively pre-crushed and pre-dried at 75°C for 18 h and reserved;

[0042] S1: By mass, the linear corn starch, the hydrophobic modified corn starch and the tapioca acetylated distarch phosphate are evenly mixed at 75°C, and then the stearic acid-modified micron titanium dioxide is added for even mixing; then the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, the polycaprolactone and the chitosan quaternary ammonium salt are added and mixed evenly; then the composite plasticizer, the composite heat stabilizer and stearic acid are added and mixed evenly at 65°C to obtain the base material;

[0043] S2: Add the base material into a twin-screw extruder for melt blending and extrusion. The extrusion temperature is 165 °C and the screw speed is 280 r / min; cool and draw the extruded material into strands and pelletize it to obtain pellets of the fully biodegradable polymer composite material.

[0044] Example 2

[0045] A fully biodegradable polymer composite material for tableware, comprising the following raw materials in parts by mass: 3 parts of linear corn starch, 10 parts of hydrophobically modified corn starch, 10 parts of tapioca acetylated distarch phosphate, 30 parts of a poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, 8 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 3 parts of polycaprolactone, 1 part of stearic acid-modified micron-sized titanium dioxide, 2 parts of chitosan quaternary ammonium salt, 5 parts of a composite plasticizer, 3 parts of a composite heat stabilizer, and 0.3 part of stearic acid.

[0046] Among them, the preparation method of the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material includes: according to the mass ratio of poly(lactic acid) to poly(butylene succinate) being 1:1 and the dosage of rosmarinic acid being 3% of the total mass of poly(lactic acid) and poly(butylene succinate), mix poly(lactic acid), poly(butylene succinate), and rosmarinic acid evenly at 80 °C, and then use a twin-screw extruder for extrusion. The extrusion temperature is 165 °C and the screw speed is 250 r / min. The material is fully melted and kneaded under high temperature and the shearing action of the screw to form an interpenetrating network structure; cool and draw the extruded material into strands and pelletize it to obtain the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material.

[0047] Among them, the preparation method of the stearic acid-modified micron-sized titanium dioxide includes: according to the mass ratio of micron-sized titanium dioxide to stearic acid being 10:1, dissolve stearic acid in ethanol at 60 °C which is 100 times the mass of stearic acid, then add micron-sized titanium dioxide, disperse it evenly by ultrasonic wave at 30 KHz, stir and react at 300 r / min for 1 h, evaporate and recover ethanol, dry the solid in vacuum at 40 °C until constant weight, and break it up to obtain stearic acid-modified micron-sized titanium dioxide.

[0048] Among them, the composite plasticizer is a composite plasticizer with the mass ratio of tributyl citrate to epoxidized soybean oil being 3:1.

[0049] Among them, the composite heat stabilizer is a composite plasticizer with the mass ratio of iron pyrophosphate to zinc stearate being 2:1.

[0050] The preparation method of the above-mentioned fully biodegradable polymer composite material for tableware includes the following steps:

[0051] The linear corn starch, hydrophobically modified corn starch, and tapioca acetylated distarch phosphate were pre-dried at 70 °C for 12 h respectively and reserved; the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt were pre-crushed respectively and pre-dried at 70 °C for 12 h and reserved;

[0052] S1: By mass fraction, the linear corn starch, hydrophobically modified corn starch, and tapioca acetylated distarch phosphate were uniformly mixed at 70 °C, and then stearic acid-modified micron titanium dioxide was added for uniform mixing; then the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt were added and mixed evenly; then a composite plasticizer, a composite heat stabilizer, and stearic acid were added and mixed evenly at 60 °C to obtain a base material;

[0053] S2: The base material was added to a twin-screw extruder for melt blending and extrusion. The extrusion temperature was 160 °C and the screw speed was 250 r / min; it was air-cooled and drawn into strips and pelletized to obtain the pellets of the fully biodegradable polymer composite material.

[0054] Example 3

[0055] A fully biodegradable polymer composite material for tableware, comprising the following raw materials by mass fraction: 3 parts of linear corn starch, 15 parts of hydrophobically modified corn starch, 10 parts of tapioca acetylated distarch phosphate, 40 parts of poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, 8 parts of the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 5 parts of polycaprolactone, 1 part of stearic acid-modified micron titanium dioxide, 4 parts of chitosan quaternary ammonium salt, 5 parts of composite plasticizer, 5 parts of composite heat stabilizer, and 0.3 part of stearic acid.

[0056] Among them, the preparation method of the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material includes: according to the mass ratio of poly(lactic acid) to poly(butylene succinate) being 1.5:1 and the dosage of rosmarinic acid being 3% of the total mass of poly(lactic acid) and poly(butylene succinate), poly(lactic acid), poly(butylene succinate), and rosmarinic acid were mixed evenly at 90 °C, and then extruded by a twin-screw extruder. The extrusion temperature was 165 °C and the screw speed was 300 r / min. The materials were fully melted and kneaded under high temperature and the shearing action of the screw to form an interpenetrating network structure; it was air-cooled and drawn into strips and pelletized to obtain the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material.

[0057] Among them, the preparation method of stearic acid-modified micron titanium dioxide includes: dissolving stearic acid in ethanol at 60°C with a mass 150 times that of stearic acid according to the mass ratio of micron titanium dioxide to stearic acid being 10:1, then adding micron titanium dioxide, dispersing evenly by ultrasonic wave at 50 KHz, stirring and reacting at 300 r / min for 2 h, evaporating and recovering ethanol, drying the solid in vacuum at 40°C until constant weight, and breaking up to obtain stearic acid-modified micron titanium dioxide.

[0058] Among them, the composite plasticizer is a composite plasticizer with the mass ratio of tributyl citrate to epoxidized soybean oil being 4:1.

[0059] Among them, the composite heat stabilizer is a composite plasticizer with the mass ratio of iron pyrophosphate to zinc stearate being 3:1.

[0060] The preparation method of the above-mentioned fully biodegradable polymer composite material for tableware includes the following steps:

[0061] Pre-drying linear corn starch, hydrophobically modified corn starch and tapioca acetylated distarch phosphate at 80°C for 12 h respectively for standby; pre-crushing the interpenetrating network structure material of polylactic acid-polybutylene succinate, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt respectively, and pre-drying at 80°C for 12 h for standby;

[0062] S1: By mass, uniformly mixing linear corn starch, hydrophobically modified corn starch and tapioca acetylated distarch phosphate at 80°C, then adding stearic acid-modified micron titanium dioxide for uniform mixing; then adding the interpenetrating network structure material of polylactic acid-polybutylene succinate, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt, and mixing evenly; then adding the composite plasticizer, the composite heat stabilizer and stearic acid, and mixing evenly at 60°C to obtain the base material;

[0063] S2: Adding the base material into a twin-screw extruder for melt blending and extrusion, the extrusion temperature is 170°C, and the screw speed is 250 r / min; air-cooling and pulling into strips, and pelletizing to obtain the pellets of the fully biodegradable polymer composite material.

[0064] Example 4

[0065] A fully biodegradable polymer composite material for tableware, comprising the following raw materials in parts by mass: 5 parts of linear corn starch, 15 parts of hydrophobically modified corn starch, 15 parts of tapioca acetylated distarch phosphate, 40 parts of the interpenetrating network structure material of polylactic acid-polybutylene succinate, 10 parts of the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 5 parts of polycaprolactone, 2 parts of stearic acid-modified micron titanium dioxide, 4 parts of chitosan quaternary ammonium salt, 8 parts of composite plasticizer, 5 parts of composite heat stabilizer and 1 part of stearic acid.

[0066] Among them, the preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: according to the mass ratio of polylactic acid to polybutylene succinate being 1.5:1 and the dosage of rosmarinic acid being 5% of the total mass of polylactic acid and polybutylene succinate, polylactic acid, polybutylene succinate and rosmarinic acid are mixed evenly at 90 °C, and then extruded by a twin-screw extruder. The extrusion temperature is 180 °C, the screw speed is 300 r / min, and the material is fully melted and kneaded under the action of high temperature and the shear of the screw to form an interpenetrating network structure; air-cooled and drawn into strips, and pelletized to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0067] Among them, the preparation method of the stearic acid-modified micron titanium dioxide includes: according to the mass ratio of micron titanium dioxide to stearic acid being 10:1.5, stearic acid is dissolved in ethanol at 65 °C which is 150 times the mass of stearic acid, and then micron titanium dioxide is added. It is ultrasonically dispersed evenly at 50 KHz, stirred and reacted at 500 r / min for 2 h, the ethanol is evaporated and recovered, and the solid is vacuum dried at 50 °C to constant weight and then dispersed to obtain the stearic acid-modified micron titanium dioxide.

[0068] Among them, the composite plasticizer is a composite plasticizer with the mass ratio of tributyl citrate to epoxidized soybean oil being 4:1.5.

[0069] Among them, the composite heat stabilizer is a composite plasticizer with the mass ratio of ferric pyrophosphate to zinc stearate being 3:1.5.

[0070] The preparation method of the above-mentioned fully biodegradable polymer composite material for tableware includes the following steps:

[0071] The linear corn starch, the hydrophobic modified corn starch and the tapioca acetylated distarch phosphate are respectively pre-dried at 80 °C for 24 h and reserved; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, the polycaprolactone and the chitosan quaternary ammonium salt are respectively pre-crushed and pre-dried at 80 °C for 24 h and reserved;

[0072] S1: By mass, the linear corn starch, the hydrophobic modified corn starch and the tapioca acetylated distarch phosphate are evenly mixed at 80 °C, and then the stearic acid-modified micron titanium dioxide is added for even mixing; then the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, the polycaprolactone and the chitosan quaternary ammonium salt are added and mixed evenly; then the composite plasticizer, the composite heat stabilizer and stearic acid are added and mixed evenly at 70 °C to obtain the base material;

[0073] S2: Add the base material into a twin-screw extruder for melt blending and extrusion. The extrusion temperature is 170 °C and the screw speed is 300 r / min; cool by air and draw into strips, then pelletize to obtain the pellets of the fully biodegradable polymer composite material.

[0074] Example 5

[0075] A fully biodegradable polymer composite material for tableware, comprising the following raw materials in parts by mass: 5 parts of linear corn starch, 10 parts of hydrophobically modified corn starch, 15 parts of tapioca acetylated distarch phosphate, 30 parts of a poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, 10 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 3 parts of polycaprolactone, 2 parts of stearic acid-modified micron titanium dioxide, 2 parts of chitosan quaternary ammonium salt, 8 parts of a composite plasticizer, 3 parts of a composite heat stabilizer, and 1 part of stearic acid.

[0076] Among them, the preparation method of the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material includes: according to the mass ratio of poly(lactic acid) to poly(butylene succinate) being 1:1 and the dosage of rosmarinic acid being 5% of the total mass of poly(lactic acid) and poly(butylene succinate), mix poly(lactic acid), poly(butylene succinate), and rosmarinic acid evenly at 80 °C, then use a twin-screw extruder for extrusion. The extrusion temperature is 180 °C and the screw speed is 250 r / min. The materials are fully melted and kneaded under high temperature and the shearing action of the screw to form an interpenetrating network structure; cool by air and draw into strips, then pelletize to obtain the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material.

[0077] Among them, the preparation method of the stearic acid-modified micron titanium dioxide includes: according to the mass ratio of micron titanium dioxide to stearic acid being 10:1.5, dissolve stearic acid in ethanol at 65 °C which is 100 times the mass of stearic acid, then add micron titanium dioxide, disperse evenly by ultrasonic wave at 30 KHz, stir and react at 500 r / min for 1 h, evaporate and recover ethanol, dry the solid in vacuum at 50 °C until constant weight, and break up to obtain the stearic acid-modified micron titanium dioxide.

[0078] Among them, the composite plasticizer is a composite plasticizer with the mass ratio of tributyl citrate to epoxidized soybean oil being 3:1.5.

[0079] Among them, the composite heat stabilizer is a composite plasticizer with the mass ratio of ferric pyrophosphate to zinc stearate being 2:1.5.

[0080] The preparation method of the above-mentioned fully biodegradable polymer composite material for tableware includes the following steps:

[0081] The linear corn starch, hydrophobically modified corn starch, and tapioca acetylated distarch phosphate were respectively pre-dried at 70 °C for 24 h and reserved; the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and quaternary ammonium chitosan were respectively pre-crushed and pre-dried at 70 °C for 24 h and reserved;

[0082] S1: By mass, the linear corn starch, hydrophobically modified corn starch, and tapioca acetylated distarch phosphate were uniformly mixed at 70 °C, and then stearic acid-modified micron titanium dioxide was added for uniform mixing; then the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and quaternary ammonium chitosan were added and mixed evenly; then a composite plasticizer, a composite heat stabilizer, and stearic acid were added and mixed evenly at 70 °C to obtain a base material;

[0083] S2: The base material was added to a twin-screw extruder for melt blending and extrusion. The extrusion temperature was 160 °C, and the screw speed was 300 r / min; it was air-cooled and drawn into strips and pelletized to obtain pellets of the fully biodegradable polymer composite material.

[0084] In the above-mentioned examples, the average molecular weight of the linear corn starch was 160,000, and it was sourced from Hubei Langbowan Biopharmaceutical Co., Ltd. The hydrophobically modified corn starch was sourced from Guangzhou Jiexin Chemical Co., Ltd., with the model number 0301 and a particle size below 200 mesh. The tapioca acetylated distarch phosphate was sourced from Weifang Senruit Biotechnology Co., Ltd. The copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate was sourced from Dongguan Jiatianxia Plastic Raw Materials Co., Ltd., with the model number yu-3824. The quaternary ammonium chitosan was sourced from Xi'an Dongchi Biotechnology Co., Ltd., with the model number HACC-102. The stearic acid was sourced from Guangzhou Suixin Chemical Co., Ltd. The polycaprolactone was sourced from Jinan Zhongrui Chemical Co., Ltd., with the model number ZR36. The polylactic acid was sourced from Foshan Guangzheng Chemical Co., Ltd., with the model number FB-01, and the poly(butylene succinate) was sourced from Dongguan Yuefa Plastic Raw Materials Co., Ltd., with the model number FZ92; rosmarinic acid was sourced from Shaanxi Linzhou Biotechnology Co., Ltd., with the model number LZ-MDXS. The micron titanium dioxide was sourced from Zhuyu New Materials Technology Co., Ltd., with the model number ZY-G20 and passing through a 460-mesh sieve. The tributyl citrate was sourced from Jinan Jiyang Hongfa Chemical Industry. The epoxidized soybean oil was sourced from Guangzhou Runquan Chemical Co., Ltd.; the ferric pyrophosphate was sourced from Wuhan Baixing Biotechnology Co., Ltd. The zinc stearate was sourced from Dongguan Shanyi Plasticizing Co., Ltd.

[0085] Comparative Example 1

[0086] In the fully biodegradable polymer composite material, the linear corn starch was replaced with hydrophobically modified corn starch; other parameters and methods were the same as in Example 1.

[0087] Comparative Example 2

[0088] In the fully biodegradable polymer composite material, tapioca acetylated distarch phosphate is replaced with hydrophobically modified corn starch; other parameters and methods are the same as in Example 1.

[0089] Comparative Example 3

[0090] In the fully biodegradable polymer composite material, both linear corn starch and tapioca acetylated distarch phosphate are replaced with hydrophobically modified corn starch; other parameters and methods are the same as in Example 1.

[0091] Comparative Example 4

[0092] In the preparation method of the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material, rosmarinic acid is not added; other parameters and methods are the same as in Example 1.

[0093] Comparative Example 5

[0094] In the fully biodegradable polymer composite material, the addition amount of the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material is reduced from 35 parts to 15 parts, and the remaining 20 parts are replaced with a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate; other parameters and methods are the same as in Example 1.

[0095] Comparative Example 6

[0096] In the fully biodegradable polymer composite material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate is replaced with the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material; other parameters and methods are the same as in Example 1.

[0097] Comparative Example 7

[0098] In the fully biodegradable polymer composite material, polycaprolactone is not added; other parameters and methods are the same as in Example 1.

[0099] Comparative Example 8

[0100] Stearic acid-modified micron titanium dioxide is replaced with micron titanium dioxide without modification; other parameters and methods are the same as in Example 1.

[0101] Comparative Example 9

[0102] In the composite heat stabilizer, all are ferric pyrophosphate; other parameters and methods are the same as in Example 1.

[0103] Comparative Example 10

[0104] In the composite heat stabilizer, all are zinc stearate; other parameters and methods are the same as in Example 1.

[0105] Comparative Example 11

[0106] In the composite plasticizer, tributyl citrate is used entirely; other parameters and methods are the same as those in Example 1.

[0107] Comparative Example 12

[0108] In the composite plasticizer, epoxidized soybean oil is used entirely; other parameters and methods are the same as those in Example 1.

[0109] Perform performance tests on the materials prepared in the above examples and comparative examples; the injection temperature of the specimen is 170 °C, and the holding pressure is 80 MPa.

[0110] I. Tensile strength test: Refer to GB / T 1040.2 "Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics" for testing. The total length of the specimen is controlled at 150 mm, the gauge length is 50 mm, the width is 10 mm, the thickness is 4 mm, and 5 parallel specimens are prepared for each group. Use a universal material testing machine for tensile testing. When the specimen breaks, record the maximum load and calculate the tensile strength; the average test results are shown in Table 1 below.

[0111] II. Flexural strength test: Refer to GB / T 9341 "Plastics - Determination of flexural properties" for testing. The length of the specimen is set at 80 mm, the width is 10 mm, the thickness is 4 mm, and 5 parallel specimens are prepared for each group. Use a universal material testing machine for flexural test. When the specimen is damaged, record the maximum load and calculate the flexural strength. The average test results are shown in Table 1 below.

[0112] III. Heat distortion temperature test: Refer to GB / T 1634.2 "Plastics - Determination of heat deflection temperature - Part 2: Plastics, rigid rubbers and long fibre-reinforced composites" for testing. Prepare specimens with dimensions of 120 mm × 15 mm × 4 mm, and prepare 3 parallel specimens for each group. Use a heat distortion and Vicat softening point temperature tester for testing. Place the specimen on the heating table of the instrument, apply a load of 1.8 MPa, and uniformly heat the specimen at a heating rate of 120 °C / h. During the heating process, the bending deformation of the specimen is monitored in real time through the high-precision displacement sensor of the instrument. When the bending deformation of the specimen reaches 0.21 mm, record the temperature at this time, and this temperature is the heat distortion temperature. The average test results are shown in Table 1 below.

[0113] IV. Water absorption test: Process the material into thin sheets with dimensions of 50 mm × 50 mm × 4 mm, and make 5 parallel specimens for each group. First, place the specimens in an oven at 105 °C and dry them to a constant weight, and record the mass m 0 ; then, completely immerse the dried specimens in distilled water at 25 °C. After soaking for 24 h, take out the specimens, gently blot the surface moisture with filter paper, and immediately weigh them to record the mass m 1 . Water absorption = (m 1 - m0 ) ÷ m 0 × 100%; The average test results are shown in Table 1 below.

[0114] V. Degradation rate detection: The material is made into circular flakes with a diameter of 50 mm and a thickness of 2 mm, weighed, and denoted as M 0 , and 5 parallel samples are prepared for each group. Select soil rich in microorganisms, adjust and maintain the soil humidity at 60%, control the temperature at 30 °C, and simulate natural environmental conditions. The sample is buried in the soil, taken out every 30 days, washed, and then the sample is placed in an oven at 60 °C and dried to a constant weight and weighed, and the mass M 1 is recorded. Degradation rate = (M 0 - M 1 ) ÷ M 0 × 100%; The detection period is set to 180 days. The average test results are shown in Table 1 below.

[0115] Table 1 Test Results

[0116]

[0117]

[0118] From the above results, it can be seen that the materials of Examples 1 to 5 have good service performance, better tensile strength and flexural strength, better mechanical strength, are not easily brittle, have good heat and water resistance, and are more conducive to rapid degradation.

[0119] From the results of Comparative Example 1, it can be seen that the linear amylose molecules have a linear structure and certain crystallinity, and can provide rigid support like a "skeleton" in the material system, enhancing the tensile and flexural strength of the material. When hydrophobic modified corn starch is used to replace amylose, the molecular structure of hydrophobic modified corn starch changes, and its rigidity is lower than that of amylose, resulting in a decrease in the overall rigidity of the material. The crystalline structure of amylose has a positive effect on the thermal stability of the material. After replacement, the internal crystalline structure of the material changes, and the heat distortion temperature decreases. In addition, the hydrophilicity of hydrophobic modified corn starch is different from that of amylose. When preparing the material, the molecular binding structure is different, and the water absorption changes. In terms of degradation, due to the change in the starch structure, the action sites and methods of microorganisms on the material change, resulting in a decrease in the degradation rate.

[0120] From the results of Comparative Example 2, it can be seen that cassava acetylated distarch phosphate contains special chemical groups, which can interact with other material components to form a relatively tight structure, thus making an important contribution to the mechanical properties of the material. When it is replaced by hydrophobically modified corn starch, the interaction inside the material weakens, and the overall mechanical properties deteriorate. The special structure of cassava acetylated distarch phosphate helps to improve the thermal stability of the material, and the heat distortion temperature decreases after replacement. During the degradation process, due to the change of the starch structure, the ease of microbial action changes, and the degradation rate changes.

[0121] From the results of Comparative Example 3, it can be seen that simultaneously replacing linear corn starch and cassava acetylated distarch phosphate fundamentally changes the structure and properties of the starch part in the material, and the structural integrity of the material is greatly damaged. The rigid support and interaction network originally provided by linear corn starch and cassava acetylated distarch phosphate are broken, resulting in a significant decrease in mechanical properties. The heat distortion temperature also decreases significantly due to the instability of the internal structure of the material. The water absorption rate increases significantly due to the change in hydrophilicity after the starch structure is changed, and the degradation rate also decreases significantly.

[0122] From the results of Comparative Example 4, it can be seen that rosmarinic acid plays a key role in the preparation of poly(lactic acid)-poly(butylene succinate) interpenetrating network structure materials. It can promote the cross-linking reaction between poly(lactic acid) and poly(butylene succinate) molecules, form a tighter connection between molecular chains, enhance the compatibility between the two polymers at the same time, enable them to act synergistically better, and also has antioxidant properties to prevent poly(lactic acid) and poly(butylene succinate) from oxidizing at high temperatures. When rosmarinic acid is not added, the formation of the interpenetrating network structure is imperfect, the intermolecular force weakens, and when the material is subjected to external tensile and bending forces, the molecular chains are prone to relative sliding and separation, resulting in a decrease in tensile strength and bending strength. The heat distortion temperature also decreases due to the weakening of intermolecular interactions.

[0123] It can be seen from the results of Comparative Example 5 (the addition amount of the polylactic acid-polybutylene succinate interpenetrating network structure material is reduced) that the polylactic acid-polybutylene succinate interpenetrating network structure material has relatively high strength and good thermal stability, and makes great contributions to the mechanical properties and thermal properties in the material system. When its addition amount is reduced from 35 parts to 15 parts, and the remaining amount is replaced with 20 parts of the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, due to the differences in the properties between the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate and the polylactic acid-polybutylene succinate interpenetrating network structure material, the synergistic effect of their combination is insufficient, and its strength and thermal stability are relatively low. This causes the overall load-bearing capacity of the material to decline, and the tensile strength and flexural strength to decrease. The heat distortion temperature also decreases due to the reduction of the heat-resistant components in the material and the change of the combined structure. In terms of water absorption rate and degradation rate, due to the change of the overall composition structure of the material, the interaction between the material and water and the effect of microorganisms on the material change.

[0124] It can be seen from the results of Comparative Example 6 (replacement with the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate) that the molecular structures and performance characteristics of the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate and the polylactic acid-polybutylene succinate interpenetrating network structure material are different. After replacement, the molecular chain structure and the aggregated state structure of the material change, and various properties change.

[0125] It can be seen from the results of Comparative Example 7 (no polycaprolactone is added) that polycaprolactone has good flexibility and toughening effect, and can improve the processing performance and toughness of the material in the material system. When no polycaprolactone is added, the toughness of the material decreases, and when subjected to tensile and bending external forces, the stress concentration phenomenon inside the material is more obvious, and brittle fracture is more likely to occur. Therefore, the tensile strength and flexural strength decrease slightly, but have little effect on the heat distortion temperature, water absorption rate and degradation rate.

[0126] It can be seen from the results of Comparative Example 8 (unmodified micron titanium dioxide) that the compatibility and dispersibility between micron titanium dioxide and the matrix material are improved through the action of stearic acid for stearic acid-modified micron titanium dioxide. When unmodified micron titanium dioxide is used to replace stearic acid-modified micron titanium dioxide, the unmodified micron titanium dioxide is prone to agglomeration in the matrix and cannot be evenly dispersed in the material, so it cannot effectively transfer stress and enhance the performance of the material. This causes the stress not to be evenly distributed when the material is subjected to external forces, and stress concentration is likely to occur around the agglomerated micron titanium dioxide particles, resulting in a decrease in tensile strength, flexural strength, and heat distortion temperature. During the degradation process, due to the change in the dispersion state of micron titanium dioxide, it also has a certain impact on the degradation process of the material.

[0127] From the results of Comparative Example 9, it can be seen that: in the composite heat stabilizer, iron pyrophosphate and zinc stearate play a synergistic heat stabilizing role in a specific ratio. Iron pyrophosphate can capture the free radicals generated during the heating process of the material and inhibit the progress of the thermal degradation reaction; while zinc stearate can stabilize the chemical structure of the material by reacting with the acidic substances in the material. When all iron pyrophosphate is used, although it can inhibit the generation of free radicals to a certain extent, the reaction effect of zinc stearate with acidic substances is lost, the stability of the chemical structure of the material during heating decreases, it is more likely to undergo thermal degradation and structural changes, and the mechanical properties are also affected.

[0128] From the results of Comparative Example 10, it can be seen that: similarly, when all zinc stearate is used, although it can stabilize the chemical structure of the material to a certain extent, it cannot effectively inhibit the generation of free radicals. The thermal degradation reaction induced by free radicals during heating of the material is intensified, the thermal stability becomes poor, and the mechanical properties also decrease accordingly.

[0129] From the results of Comparative Example 11, it can be seen that: in the composite plasticizer, tributyl citrate and epoxidized soybean oil play a plasticizing role in a specific ratio. The molecules of tributyl citrate and epoxidized soybean oil can insert between the polymer molecular chains, weaken the intermolecular forces, and endow the material with better flexibility and processability. When all tributyl citrate is used, since its individual action cannot achieve the best plasticizing effect, the flexibility and processability of the material decrease. This limits the sliding between the molecular chains when the material is subjected to external forces, and the heat distortion temperature is also affected to a certain extent.

[0130] From the results of Comparative Example 12, it can be seen that: when all epoxidized soybean oil is used, the best plasticizing effect cannot be achieved either. When epoxidized soybean oil acts alone, it cannot weaken the intermolecular forces between polymer molecular chains as comprehensively as the composite plasticizer, resulting in a decrease in material properties.

Claims

1. A fully degradable polymer composite material for tableware, characterized in that: The invention comprises the following raw materials in parts by weight: 3 to 5 parts of linear corn starch, 10 to 15 parts of hydrophobically modified corn starch, 10 to 15 parts of acetylated distarch phosphate of cassava, 30 to 40 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 8 to 10 parts of copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, 3 to 5 parts of polycaprolactone, 1 to 2 parts of stearic acid modified micron titanium dioxide, 2 to 4 parts of chitosan quaternary ammonium salt, 5 to 8 parts of composite plasticizer, 3 to 5 parts of composite thermal stabilizer and 0.3 to 1 part of stearic acid.

2. A fully degradable polymer composite material for tableware according to claim 1, characterized in that: The preparation method of polylactic acid-polybutylene succinate interpenetrating network structure material comprises: uniformly mixing polylactic acid, polybutylene succinate and rosmarinic acid at 80°C to 90°C, then extruding with a twin-screw extruder, air-cooling and drawing, and pelletizing to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

3. A fully degradable polymer composite material for tableware according to claim 2, characterized in that: The mass ratio of polylactic acid to polybutylene succinate is (1-1.5):1; the amount of rosmarinic acid is 3%-5% of the total mass of polylactic acid and polybutylene succinate; the extrusion temperature of the twin-screw extruder is 165° C.-180° C., and the screw speed is 250 r / min-300 r / min.

4. A fully degradable polymer composite material for tableware according to claim 1, characterized in that: The preparation method of stearic acid modified micron titanium dioxide comprises: dissolving stearic acid in ethanol, then adding micron titanium dioxide, uniformly dispersing by ultrasonication, stirring for reaction, evaporating and recovering ethanol, vacuum drying and breaking up the solid to obtain stearic acid modified micron titanium dioxide.

5. A fully degradable polymer composite material for tableware according to claim 4, characterized in that: The mass ratio of micron titanium dioxide to stearic acid is 10:(1-1.5); the amount of ethanol used is 100-150 times the mass of stearic acid, and the temperature of ethanol is 60-65°C; the stirring reaction time is 1-2h, and the stirring reaction speed is 300-500r / min; the vacuum drying temperature is 40-50°C, and the vacuum drying is performed to constant weight.

6. A fully degradable polymer composite material for tableware according to claim 1, characterized in that: The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxidized soybean oil of (3-4):(1-1.5).

7. A fully degradable polymer composite material for tableware according to claim 1, characterized in that: The composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of (2-3):(1-1.5).

8. A method for preparing a fully degradable polymer composite material for tableware, used for preparing the fully degradable polymer composite material for tableware according to claim 1, characterized in that: The preparation method comprises the following steps: S1: According to the mass fraction, straight-chain corn starch, hydrophobically modified corn starch and acetylated distarch phosphate of cassava are uniformly mixed at 70°C to 80°C, and then stearic acid-modified micronized titanium dioxide is added and uniformly mixed; then polylactic acid-polybutylene succinate interpenetrating network structure material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt are added and uniformly mixed; then composite plasticizer, composite heat stabilizer and stearic acid are added and uniformly mixed at 60°C to 70°C to obtain a base material; S2: adding the base material into a twin-screw extruder for melt blending and extrusion, air cooling and drawing, and pelletizing to obtain pellets of a fully degradable polymer composite material.

9. The method for preparing a fully degradable polymer composite material for tableware according to claim 8, characterized in that: The linear corn starch, hydrophobically modified corn starch and acetylated distarch phosphate of cassava are pre-dried; the polylactic acid-polybutylene succinate interpenetrating network structure material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt are pre-crushed and dried.

10. The method for preparing a fully degradable polymer composite material for tableware according to claim 8, characterized in that: The extrusion temperature of the twin-screw extruder is 160°C to 170°C, and the screw speed is 250r / min to 300r / min.

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