CN111500037B - A kind of high-density bamboo powder modified polylactic acid biodegradable plastic and preparation method thereof - Google Patents

Abstract

The invention provides a high-density bamboo powder modified polylactic acid biodegradable plastic and a preparation method thereof. The high-density bamboo powder modified polylactic acid biodegradable plastic provided by the invention comprises the following components in parts by mass: 35-60 parts of polylactic acid, 25-40 parts of modified bamboo powder, 10-15 parts of starch, 1.5-2.5 parts of silicate, 3-5 parts of glycerol and 0.5-2 parts of coupling agent. According to the technical scheme, bamboo powder cellulose is subjected to graft modification treatment, the N, N-dimethyl amide/aluminum chloride mixed system is an initiator for graft copolymerization reaction of the bamboo powder cellulose and caprolactone, the hydrophilic chain segment and the lipophilic chain segment which are incompatible with each other are bonded together by adopting a graft copolymerization method, and the modified bamboo powder is easily crosslinked with polylactic acid to form a copolymer under the action of a coupling agent, so that the mechanical property of the bamboo-plastic composite material is improved, the consumption of the polylactic acid is further reduced along with the increase of the addition amount of the bamboo powder, and the cost is saved.

Description

A kind of high-density bamboo powder modified polylactic acid biodegradable plastic and preparation method thereof

technical field

The invention relates to the technical field of food packaging, in particular to a high-density bamboo powder modified polylactic acid biodegradable plastic and a preparation method thereof.

Background technique

With the improvement of public awareness of environmental protection and the increasing attention to the environment and the increasing shortage of oil resources, the research and development of biodegradable plastics has attracted extensive attention and attention in recent years. Among them, polylactic acid (PLA) is a renewable resource-based polymer, a fully biodegradable aliphatic polyester, and one of the most commercially successful biodegradable polymers at present. Polylactic acid has high strength, but its brittleness and poor heat resistance limit its application to a certain extent. In order to improve the mechanical properties of polylactic acid, bamboo fiber and plastic are organically combined to prepare a bamboo-plastic composite material, which has the characteristics of both plastic and bamboo, and the material is moisture-proof, anti-corrosion, insect-resistant, non-cracking, non-warping, non-toxic and tasteless, and It has good secondary processability and has very broad application prospects, but the interfacial compatibility between fibers and polylactic acid is relatively poor, and the addition of bamboo powder is too high, which will reduce the mechanical properties of the composite material and limit the use of bamboo-plastic composite materials. further application.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a high-density bamboo powder-modified polylactic acid biodegradable plastic and a preparation method thereof, aiming to solve the problem that the interface compatibility between fibers and polylactic acid is relatively poor, and the excessive addition of bamboo powder causes the composite material to deteriorate. The problem of reduced mechanical properties.

In order to achieve the above object, the present invention proposes a kind of high-density bamboo powder modified polylactic acid biodegradable plastic, which, in parts by mass, comprises the following components:

35-60 parts of polylactic acid, 25-40 parts of modified bamboo powder, 10-15 parts of starch, 1.5-2.5 parts of silicate, 3-5 parts of glycerin, and 0.5-2 parts of coupling agent.

Preferably, it includes the following components:

45-55 parts of polylactic acid, 30-40 parts of modified bamboo powder, 12-15 parts of starch, 1.5-2.5 parts of silicate, 3-5 parts of glycerin, and 0.5-2 parts of coupling agent.

Preferably, the preparation method of described modified bamboo powder comprises the following steps:

(1) aluminum chloride and N,N-dimethylamide are configured into N,N-dimethylamide/aluminum chloride mixed solution according to the mass ratio of 1:15～20;

(2) soak the bamboo powder in acetone solution for 15～24h, filter and freeze-dry;

(3) the bamboo powder after freeze-drying in step (2) is placed in dimethylacetamide solution and soaked for 3～8h, filtered and freeze-dried;

dimethylacetamide

(4) the bamboo powder after freeze-drying in step (3) and the N,N-dimethylamide/aluminum chloride mixed solution gained in step (1) are uniformly mixed according to the mass ratio of 1:3～6, and the mixing system is in Heat up to 150°C under nitrogen atmosphere;

(5) adding caprolactone to the mixing system of step (4), continuing to stir and react for 12h, centrifuging after completion of the reaction, washing and drying to obtain the modified bamboo powder.

Preferably, in terms of mass fraction, the amount of caprolactone added in step (5) accounts for 10-15% of the mixed system.

Preferably, the washing solvent in step (5) is dimethyl sulfoxide, and the washing times are 2 to 4 times.

Preferably, the starch is at least one of modified corn starch and modified wheat starch.

Preferably, the silicate is layered silicate, including any one or more of aluminum silicate, calcium silicate, magnesium silicate, sodium silicate, and potassium silicate.

Preferably, the coupling agent is one of a silane coupling agent and a titanate coupling agent.

In order to achieve the above purpose, the present invention also proposes a method for preparing a high-density bamboo powder-modified polylactic acid biodegradable plastic, comprising the above-mentioned components of the high-density bamboo powder-modified polylactic acid biodegradable plastic, including the following steps:

(1) polylactic acid, modified bamboo powder, starch, silicate, glycerin and coupling agent are put into high-speed mixer in proportion and mixed to obtain mixed material;

(2) adding the mixed raw materials described in step (1) from the feed port of the twin-screw extruder, and controlling the extrusion temperature to extrude and granulate between 125 and 150°C;

(3) Extruding and granulating the sample obtained by step (2) through a single-screw extruder, controlling the extrusion temperature to be between 125 and 160° C., extruding and dicing.

The technical scheme of the present invention is that the bamboo powder cellulose is subjected to graft modification treatment, and the N,N-dimethylamide/aluminum chloride mixed system is the initiator for the graft copolymerization reaction of bamboo powder cellulose and caprolactone, and the The hydrophilic and lipophilic and mutually incompatible segments are bonded together by the graft copolymerization method, and the modified bamboo powder is easily cross-linked with polylactic acid to form a copolymer under the action of the coupling agent, which not only improves the The mechanical properties of the bamboo-plastic composite material, and with the increase of the amount of bamboo powder added, the amount of polylactic acid is further reduced, which is conducive to saving costs. During the implementation of this scheme, the addition of layered silicate can make the dispersion of polylactic acid, bamboo powder and starch more uniform, prevent particle agglomeration, improve the grafting rate during the melting process of the three, and further improve the bamboo-plastic composite material. mechanical properties and stability.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 15kg of N,N-dimethylamide are configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder is placed in an acetone solution and soaked for 15-24h, filtered and then freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under a nitrogen atmosphere; 2.5 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 hours.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 2

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 17kg of N,N-dimethylamide were configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder was placed in acetone solution and soaked for 15-24h, filtered and freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 2.7 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was obtained by washing and drying.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 3

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 20kg of N,N-dimethylamide are configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder is placed in acetone solution and soaked for 15-24h, filtered and then freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under a nitrogen atmosphere; 3.1 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was washed and dried.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 4

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 22kg of N,N-dimethylamide were configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder was soaked in acetone solution for 15-24h, filtered and freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under a nitrogen atmosphere; 3.3 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was obtained by washing and drying.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Comparative Example 1

Preparation method of bamboo powder/polylactic acid biodegradable plastic:

4.0kg polylactic acid, 2.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Mechanical property test

The tensile properties and bending properties of bamboo powder modified polylactic acid biodegradable plastics were tested by CMT-5504 universal mechanical testing machine. Tensile properties and bending properties were tested in accordance with national standards GB/T 1040-92 and GB/T 9341-2000, respectively. The test results are shown in Table 1.

Table 1. Test results of mechanical properties of polylactic acid biodegradable plastics from Examples 1 to 4 and Comparative Example 1

As can be seen from Table 1, compared to the comparative example 1, the bamboo powder is not modified, the addition of the bamboo powder in the comparative example 1 is significantly lower than the addition of the bamboo powder in the embodiments 1 to 4, and even if the bamboo powder is added. When the amount is reduced, the mechanical properties of the bamboo powder/polylactic acid composite plastic prepared in Comparative Example 1 are significantly lower than the bamboo powder-modified polylactic acid biodegradable plastics prepared in Examples 1 to 4. It shows that the bamboo powder is treated with N,N-dimethylamide/aluminum chloride mixed solution, which can improve the compatibility of bamboo powder and polylactic acid two-phase system, so as to ensure the mechanical properties of composite plastics, realize The further increase in the amount of bamboo powder added reduces the cost of materials.

Water Absorption Determination

Bamboo powder has good hydrophilicity, and its cellulose, hemicellulose, lignin and other components contain a large number of hydroxyl groups. When the composite material is in contact with water, the hydroxyl groups quickly combine with water to form hydrogen bonds and absorb water, resulting in The dimensional stability of the composite final product decreases. Therefore, it is important to modify bamboo powder to prevent a large number of hydrophilic hydroxyl groups from being exposed to water molecules, and then compound with polylactic acid to prepare bamboo powder-modified polylactic acid biodegradable plastics to reduce the water absorption of composite materials. meaning.

According to the requirements of GB1034-98 "Test Method for Water Absorption of Plastics", a sample with a size of 10mm × 10mm × 2mm was vacuum-dried at 50°C for 48h, weighed (denoted as m1), and the sample was placed at room temperature (25°C). Soak in distilled water for 24h, then take out the sample and wipe the surface with filter paper, weigh again (recorded as m2), and calculate the water absorption rate according to the following formula. The test results are shown in Table 2.

Table 2. Test results of water absorption rate of polylactic acid biodegradable plastics from Example 1 to Example 4 and Comparative Example 1

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Water absorption (%) 2.8 2.7 2.9 3.1 6.8

As can be seen from Table 2, compared with that in Comparative Example 1, the bamboo powder is not modified, and the bamboo powder-modified polylactic acid biodegradable plastics prepared in Example 1 to Example 4 all exhibit lower water absorption, indicating that the bamboo powder is After the powder is modified in the N,N-dimethylamide/aluminum chloride mixed solution, the water absorption of the bamboo powder/polylactic acid composite plastic can be significantly reduced.

Example 5

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 15kg of N,N-dimethylamide are configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder is placed in an acetone solution and soaked for 15-24h, filtered and then freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 1.5 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was washed and dried.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 6

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 15kg of N,N-dimethylamide are configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder is placed in an acetone solution and soaked for 15-24h, filtered and then freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150° C. under nitrogen atmosphere; 2.1 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 hours.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 7

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 15kg of N,N-dimethylamide are configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder is placed in an acetone solution and soaked for 15-24h, filtered and then freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under a nitrogen atmosphere; 3.1 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was washed and dried.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 8

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 15kg of N,N-dimethylamide are configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder is placed in an acetone solution and soaked for 15-24h, filtered and then freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 3.5 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 hours.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 3.0kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerol and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Mechanical property test

The tensile properties and bending properties of bamboo powder modified polylactic acid biodegradable plastics were tested by CMT-5504 universal mechanical testing machine. Tensile properties and bending properties were tested in accordance with national standards GB/T 1040-92 and GB/T 9341-2000, respectively. The test results are shown in Table 3.

Table 3. Test results of mechanical properties of bamboo powder modified polylactic acid biodegradable plastics from Example 5 to Example 8

It can be seen from Table 3 that the addition of caprolactone has an important influence on the mechanical properties of bamboo powder-modified polylactic acid biodegradable plastics. When the addition of caprolactone is too high or too low, it will lead to modified polylactic acid. The tensile and flexural properties of biodegradable plastics decrease to a certain extent. Caprolactone is a monomer of polycaprolactone. When it is mixed with bamboo powder, graft polymerization occurs under the catalysis of N,N-dimethylamide/aluminum chloride mixed system, thereby changing the molecules of bamboo powder. The arrangement structure of the chain improves the compatibility of bamboo powder and polylactic acid, and increases the addition ratio of bamboo powder in the conforming material.

Water Absorption Determination

According to the requirements of GB1034-98 "Test Method for Water Absorption of Plastics", a sample with a size of 10mm × 10mm × 2mm was vacuum-dried at 50°C for 48h, weighed (denoted as m1), and the sample was placed at room temperature (25°C). Soak in distilled water for 24h, then take out the sample and wipe the surface with filter paper, weigh again (recorded as m2), and calculate the water absorption rate according to the following formula. The test results are shown in Table 4.

Table 4. Test results of water absorption of bamboo powder modified polylactic acid biodegradable plastics from Example 5 to Example 8

Example 5 Example 6 Example 7 Example 8 Water absorption (%) 2.9 2.7 2.6 4.7

It can be seen from Table 2 that when the addition amount of caprolactone is too high, the water absorption of the modified polylactic acid biodegradable plastic increases significantly, while when the addition amount of caprolactone is lower than the prescribed content, the modified polylactic acid biodegradable plastic The water absorption has little effect. From this, it can be speculated that although caprolactone can change the hydrophilicity of the molecular segments of bamboo powder through the grafting reaction and improve the compatibility of bamboo powder and polylactic acid, too much caprolactone will preferentially interact with Polylactic acid undergoes a polymerization reaction, that is, caprolactone participates in the polymerization of polylactic acid to form a competitive reaction, resulting in incomplete reaction of bamboo powder, and the exposed hydrophilic groups are exposed to improve the hydrophilicity of the material.

Example 9

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 17kg of N,N-dimethylamide were configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder was placed in acetone solution and soaked for 15-24h, filtered and freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 2.7 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was obtained by washing and drying.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 2kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerin and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed raw material is extruded from the twin-screw The feed port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; In between, extrude and diced.

Example 10

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 17kg of N,N-dimethylamide were configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder was placed in acetone solution and soaked for 15-24h, filtered and freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 2.7 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was obtained by washing and drying.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 2.5kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerin and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

Example 11

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 17kg of N,N-dimethylamide were configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder was placed in acetone solution and soaked for 15-24h, filtered and freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 2.7 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was obtained by washing and drying.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 4kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerin and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed raw material is extruded from the twin-screw The feed port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; In between, extrude and diced.

Example 12

The preparation method of modified bamboo powder:

1kg of aluminum chloride and 17kg of N,N-dimethylamide were configured into a mixed solution of N,N-dimethylamide/aluminum chloride; 5kg of bamboo powder was placed in acetone solution and soaked for 15-24h, filtered and freeze-dried; The freeze-dried bamboo powder is soaked in a dimethylacetamide solution for 3 to 8 hours, filtered and then freeze-dried; the freeze-dried bamboo powder is then mixed with the N,N-dimethylamide/aluminum chloride mixed solution. , the mixed system was heated to 150°C under nitrogen atmosphere; 2.7 kg of caprolactone was added to the mixed system, and the reaction was continued for 12 h. After the reaction was completed, centrifugal separation was performed, and the modified bamboo powder was obtained by washing and drying.

The preparation method of bamboo powder modified polylactic acid biodegradable plastic:

4.0kg polylactic acid, 4.5kg modified bamboo powder, 1.2kg starch, 0.15kg silicate, 0.35kg glycerin and 0.1kg coupling agent are put into the high-speed mixer and mixed to obtain the mixed material; the mixed material is extruded from the twin-screw The feeding port of the machine is added, and the extrusion temperature is controlled to be between 125 and 150 ° C for extrusion and granulation; °C, extruded and pelletized.

The tensile properties and bending properties of bamboo powder modified polylactic acid biodegradable plastics were tested by CMT-5504 universal mechanical testing machine. Tensile properties and bending properties were tested in accordance with national standards GB/T 1040-92 and GB/T 9341-2000, respectively. The test results are shown in Table 5.

Table 5. Test results of mechanical properties of bamboo powder modified polylactic acid biodegradable plastics from Example 9 to Example 12

As can be seen from Table 5, the bamboo powder modified polylactic acid biodegradable plastic prepared by the application, its bamboo powder addition amount can be close to the consumption of polylactic acid, that is, the mechanical properties of the bamboo powder modified polylactic acid biodegradable plastic are not significantly changed. Under the same conditions, reducing the amount of polylactic acid can further reduce the preparation cost of the material. However, when the mass ratio of bamboo powder and polylactic acid is 1:1, the tensile properties and bending properties of the prepared bamboo powder-modified polylactic acid biodegradable plastic begin to decrease significantly, that is, the amount of bamboo powder and polylactic acid needs to be controlled. The ratio does not exceed 1.

The above-mentioned serial numbers of the embodiments of the present invention are only for description, and do not represent the advantages or disadvantages of the embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the conception of the present invention, the equivalent structural transformations made by the description of the present invention are used, or directly/indirectly applied to other related technologies. All fields are included in the scope of patent protection of the present invention.

Claims (7)

1. The high-density bamboo powder modified polylactic acid biodegradable plastic is characterized by comprising the following components in parts by weight:

35-60 parts of polylactic acid, 25-40 parts of modified bamboo powder, 10-15 parts of starch, 1.5-2.5 parts of silicate, 3-5 parts of glycerol and 0.5-2 parts of coupling agent;

the preparation method of the modified bamboo powder comprises the following steps:

(1) preparing aluminum chloride and N, N-dimethyl amide into an N, N-dimethyl amide/aluminum chloride mixed solution according to the mass ratio of 1: 15-20;

(2) soaking the bamboo powder in an acetone solution for 15-24 h, filtering, and freeze-drying;

(3) soaking the bamboo powder subjected to freeze drying in the step (2) in a dimethylacetamide solution for 3-8 h, filtering, and freeze drying;

(4) uniformly mixing the bamboo powder subjected to freeze drying in the step (3) with the N, N-dimethyl amide/aluminum chloride mixed solution obtained in the step (1) according to the mass ratio of 1: 3-6, and heating the mixed system to 150 ℃ in a nitrogen atmosphere^oC；

(5) Adding caprolactone into the mixed system obtained in the step (4), continuously stirring and reacting for 12 hours, centrifugally separating after the reaction is finished, washing and drying to obtain the modified bamboo powder;

in the step (5), the addition amount of the caprolactone accounts for 10-15% of the mixed system.

2. The high-density bamboo powder modified polylactic acid biodegradable plastic as claimed in claim 1, which comprises the following components:

45-55 parts of polylactic acid, 30-40 parts of modified bamboo powder, 12-15 parts of starch, 1.5-2.5 parts of silicate, 3-5 parts of glycerol and 0.5-2 parts of coupling agent.

3. The high-density bamboo powder modified polylactic acid biodegradable plastic as claimed in claim 1, wherein the washing solvent in the step (5) is dimethyl sulfoxide, and the number of washing times is 2-4.

4. The high-density bamboo powder modified polylactic acid biodegradable plastic as claimed in claim 1, wherein the starch is at least one of modified corn starch and modified wheat starch.

5. The high-density bamboo powder modified polylactic acid biodegradable plastic as claimed in claim 1, wherein the silicate is a layered silicate comprising: any one or more of aluminum silicate, calcium silicate, magnesium silicate, sodium silicate and potassium silicate.

6. The high-density bamboo powder modified polylactic acid biodegradable plastic as claimed in claim 1, wherein the coupling agent is one of a silane coupling agent and a titanate coupling agent.

7. A preparation method of high-density bamboo powder modified polylactic acid biodegradable plastic, which comprises the components of the high-density bamboo powder modified polylactic acid biodegradable plastic as claimed in any one of claims 1 to 6, and is characterized by comprising the following steps:

(1) proportionally placing polylactic acid, modified bamboo powder, starch, silicate, glycerol and a coupling agent into a high-speed mixer to be mixed to obtain a mixed material;

(2) adding the mixed raw materials in the step (1) from a feeding port of a double-screw extruder, and controlling the extrusion temperature to be 125-150 DEG C^oC, extruding and granulating;

(3) extruding and molding the sample obtained by extruding and granulating in the step (2) by a single-screw extruder, and controlling the extrusion temperature to be 125-160 DEG^oAnd C, extruding and pelletizing.