阅读说明：本技术 一种植物木粉/蒙脱土填充的高性能全生物降解聚乳酸复合材料的制备方法 (Preparation method of plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material ) 是由 王杰 李晖 李军 蒋洪石 卫博慧 于 2020-05-15 设计创作，主要内容包括：本发明涉及一种植物木粉/蒙脱土填充的高性能全生物降解聚乳酸复合材料的制备方法。按照以下步骤完成：1、植物木粉需经过尿素溶胀、酶解预处理；2、预处理后的植物木粉与有机改性的蒙脱土进行球磨分散；3、分散良好的木粉/蒙脱土填料,通过密炼机或转矩流变仪,以PBAT和PBAT-co-PLA为树脂基体,制备填料母粒；4、通过双螺杆熔融共混,制备聚乳酸复合材料,由包含以下重量份的组成进行制备：聚乳酸、PBAT、PBAT-co-PLA、木粉/蒙脱土填料母粒、扩链活化剂、润滑剂、抗氧剂。本发明具有较好韧性和强度,可促进天然木粉在生物降解塑料领域的应用,特别是市场需求较大的家居内饰、汽车内饰、园林建筑结构材料以及增材制造等方面的应用。(The invention relates to a preparation method of a plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material, which comprises the following steps of 1, carrying out urea swelling and enzymolysis pretreatment on the plant wood powder, 2, carrying out ball milling dispersion on the pretreated plant wood powder and organically modified montmorillonite, 3, preparing a filler master batch by taking PBAT and PBAT-co-P L A as resin substrates through an internal mixer or a torque rheometer and preparing a polylactic acid composite material through double-screw melt blending, wherein the polylactic acid composite material is prepared from the following components in parts by weight, namely polylactic acid, PBAT-co-P L A, wood powder/montmorillonite filler master batch, chain extension activating agent, lubricant and antioxidant.)

1. A preparation method of plant wood powder/montmorillonite filled high-performance full-biodegradable polylactic acid composite material is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) and (3) urea swelling treatment: swelling plant wood powder with urea solution, and washing;

(2) and (3) activating treatment of the biological enzyme: activating the swelled plant wood powder by a biosurfactant and composite biological enzyme technology, washing and drying;

(3) preparing modified wood powder/montmorillonite mixed filler: dispersing and mixing the activated plant wood powder, the organic modified montmorillonite, the silane coupling agent and the citric acid lubricating dispersant in a ball mill to prepare a primarily dispersed and modified plant wood powder/montmorillonite mixed filler;

(4) preparing pre-dispersed mixed filler master batch, namely adding PBAT resin, PBAT-co-P L A copolymer and stearic acid lubricating plasticizer into the mixed filler which is preliminarily modified, dispersed and uniformly mixed, dispersing and coating and modifying the resin in an internal mixer or a torque rheometer at 150 ℃ under 115 ℃ and extruding and granulating after the coating and modifying are finished to obtain the pre-dispersed filler master batch;

(5) the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material is prepared from, by mass, 60-95 parts of polylactic acid, 5-40 parts of PBAT, 1-10 parts of PBAT-co-P L A, 2-45 parts of wood powder/montmorillonite filler master batch, 0.2-3 parts of chain extension active agent, 0.1-5 parts of lubricant and 0.02-1.5 parts of antioxidant, and is prepared by melt blending on a double-screw blender.

2. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, which is characterized by comprising the following steps: the urea swelling treatment in the step (1) is to mix plant wood powder in 5-20% of urea aqueous solution according to the proportion of 1: 20 weight percent of the urea solution, keeping the temperature at minus 5 ℃ to 5 ℃, and stirring for 1 to 3 hours.

3. The method for preparing the plant wood flour/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, wherein the biological enzyme activation treatment in the step (2) is to mix 0.5-1.5 parts of lignin peroxidase, 0.2-0.6 part of β -mannase, 0.2-1.0 part of xylanase, 0.2-1.5 parts of biosurfactant and 100 parts of water according to the weight ratio to obtain an active enzyme solution, and then the plant wood flour treated in the step (1) is put into the enzyme solution according to the weight ratio of 1:25 and is kept at the constant temperature for treatment at 40 ℃ for 0.5-4 hours.

4. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, which is characterized by comprising the following steps: preparing the modified wood powder/montmorillonite mixed filler in the step (3), wherein the modified montmorillonite is as follows: the weight ratio of the plant wood powder is 1: 2-20%, wherein the dosage of the silane coupling agent is 0.5-5% of the weight of the plant wood powder, and the weight of the citric acid lubricating dispersant is 0.5-8% of the weight of the plant wood powder.

5. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, wherein the pre-dispersed mixed filler master batch in the step (4) is prepared by dispersing and coating modification of the composite filler according to the weight ratio of 70-80 parts of the modified wood powder/montmorillonite composite filler, 15-25 parts of PBAT resin, 2-20 parts of PBAT-co-P L A and 1-8 parts of stearic acid lubricating plasticizer.

6. The preparation method of the plant wood flour/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, wherein the wood flour/montmorillonite polylactic acid composite material is prepared in step (5), the chain extension active agent is an ADR series product of Bassfu company and an ABC L OTADER AX8900 product of France, the lubricant is an OptiPak series lubricant and a TPW series lubricant, and the antioxidant is hindered phenol and phosphite ester.

7. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, which is characterized by comprising the following steps: the plant wood powder in the step (1) is fiber powder obtained by removing outer bast fiber from fruit trees, peach trees, poplar, willow trees, pear trees, hemp and flax, and the particle size of the wood powder is 80-400 meshes.

8. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1 or 3, which is characterized in that: the biosurfactant is one of rhamnolipid, trehalose glycolipid, mannose erythritol lipid and sophorolipid.

9. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, which is characterized by comprising the following steps: the silane coupling agent in the step (3) is an epoxy silane coupling agent, the organically modified montmorillonite is montmorillonite subjected to organic modification treatment, and the citric acid lubricant comprises one or more of triethyl citrate, tri-n-butyl citrate, tri-n-octyl citrate and tristearic citrate.

10. The preparation method of the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material according to claim 1, which is characterized by comprising the following steps: the stearic acid lubricating plasticizer in the step (4) comprises any one or a combination of pentaerythritol tetrastearate, trimethylolpropane tristearate and stearate.

Technical Field

The invention relates to the field of preparation of polymer composite materials, in particular to a preparation method of a plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material.

Background

The polymer material has light weight, easy processing and forming and good flexibility, is widely applied in various fields in recent years, and has increasingly increased market demand and consumption. However, the traditional polymer materials face huge challenges due to the excessive dependence on petroleum resources and the environmental pollution problem caused by the discarded polymer materials. Under the development background of current environmental protection and sustainable resource utilization, how to effectively utilize renewable resources is important to develop a green biodegradable polymer material.

Polylactic acid is an aliphatic polyester obtained by polymerizing lactic acid obtained by fermenting plant starch, and the raw material for producing the polylactic acid is widely available and renewable. Can be completely biodegraded, has better mechanical strength, but has larger brittleness, poor toughness, easy fracture and slower crystallization speed, and influences the processing and forming and the application in practice. Among the existing developed degradable materials, polylactic acid has relatively low cost and is a green high polymer material with the most market development prospect at present.

Plant wood fibers are the most abundant biomass resource on earth, and can also be completely biodegradable. The wood powder obtained by crushing waste wood fibers is developed and used for preparing the polymer composite material, and has important significance for relieving resource crisis, energy crisis and environmental pollution and realizing sustainable development of economy. However, wood flour structures contain a large number of polar hydroxyl functional groups on the fiber surface, are poorly compatible with polylactic acid, and tend to aggregate and phase separate. It needs to be modified to improve compatibility and dispersibility in the polymer matrix. Compared with the common plant bast fiber, the wood powder structure contains more lignin and hemicellulose, and a firm space network structure is formed between the wood powder structure and the cellulose, so that the modification effect is influenced. Therefore, it is pretreated to eliminate the steric hindrance caused by the formation of lignin and hemicellulose. Patents CN 106147173B, CN 108727793A and CN 107057389 a adopt complex enzyme or dilute sodium hydroxide solution to pretreat plant fiber or wood powder to improve modification effect. The modified effect of the pretreated wood flour is improved, but due to the hydrogen bond effect formed by polyhydroxy in cellulose, the wood flour has serious self-aggregation, is difficult to realize effective dispersion in subsequent high polymer material processing, and influences the mechanical property, particularly the toughness of polylactic acid. In order to improve the dispersion effect of wood flour, patent CN 108034211A adopts modified montmorillonite suspension to be mixed with modified wood flour, and the mixture is subjected to high pressure N₂Then, the polylactic acid composite material is prepared by dispersion, and the interfacial compatibility of the wood powder and the polylactic acid is improved by adopting maleic anhydride grafted polyolefin in the patent CN 108003582B and the patent CN 110105735A. In order to weaken the adverse effect of wood powder on the toughness of polylactic acid after filling, patent CN 108727793A, CN 109021519A, CN105585830A adopts thermoplastic elastomers such as SEBS, SBS, TPE and TPU to improve the toughness of polylactic acid.

Disclosure of Invention

The invention aims to provide a preparation method of a plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material for effectively solving the problems of dispersibility and compatibility of the plant wood powder in polylactic acid.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a preparation method of plant wood powder/montmorillonite filled high-performance full-biodegradable polylactic acid composite material is specifically completed according to the following steps:

(1) and (3) urea swelling treatment: swelling plant wood powder with urea solution, and washing;

(2) and (3) activating treatment of the biological enzyme: activating the swelled plant wood powder by a biosurfactant and composite biological enzyme technology, washing and drying;

(3) preparing modified wood powder/montmorillonite mixed filler: dispersing and mixing the activated plant wood powder, the organic modified montmorillonite, the silane coupling agent and the citric acid lubricating dispersant in a ball mill to prepare a primarily dispersed and modified plant wood powder/montmorillonite mixed filler;

(4) preparing pre-dispersed mixed filler master batch, namely adding PBAT resin, PBAT-co-P L A copolymer and stearic acid lubricating plasticizer into the mixed filler which is preliminarily modified, dispersed and uniformly mixed, dispersing and coating and modifying the resin in an internal mixer or a torque rheometer at 150 ℃ under 115 ℃ and extruding and granulating after the coating and modifying are finished to obtain the pre-dispersed filler master batch;

(5) the plant wood powder/montmorillonite filled high-performance fully biodegradable polylactic acid composite material is prepared from, by mass, 60-95 parts of polylactic acid, 5-40 parts of PBAT, 1-10 parts of PBAT-co-P L A, 2-45 parts of wood powder/montmorillonite filler master batch, 0.2-3 parts of chain extension active agent, 0.1-5 parts of lubricant and 0.02-1.5 parts of antioxidant, and is prepared by melt blending on a double-screw blender.

Further describing the technical scheme, the urea swelling treatment in the step (1) is to mix plant wood flour in 5-20% of urea aqueous solution according to the ratio of 1: 20 weight percent of the urea solution, keeping the temperature at minus 5 ℃ to 5 ℃, and stirring for 1 to 3 hours.

Further described in the above technical scheme, the biological enzyme activation treatment in step (2) is carried out by mixing 0.5-1.5 parts of lignin peroxidase, 0.2-0.6 parts of β -mannase, 0.2-1.0 parts of xylanase, 0.2-1.5 parts of biosurfactant and 100 parts of water according to the weight ratio to obtain an active enzyme solution, then putting the plant wood flour treated in step (1) into the enzyme solution according to the weight ratio of 1:25, and keeping the constant temperature at 40 ℃ for 0.5-4 hr.

Further description of the above technical scheme, the preparation of the modified wood flour/montmorillonite mixed filler in step (3), the modified montmorillonite: the weight ratio of the plant wood powder is 1: 2-20%, wherein the dosage of the silane coupling agent is 0.5-5% of the weight of the plant wood powder, and the weight of the citric acid lubricating dispersant is 0.5-8% of the weight of the plant wood powder.

The technical scheme is further described, and the pre-dispersed mixed filler master batch in the step (4) is prepared by dispersing and coating modification of the composite filler according to the weight ratio of 70-80 parts of modified wood powder/montmorillonite composite filler, 15-25 parts of PBAT resin, 2-20 parts of PBAT-co-P L A and 1-8 parts of stearic acid lubricating plasticizer.

The technical scheme is further described, in the step (5), the wood powder/montmorillonite polylactic acid composite material is prepared, the chain extension active agent is an ADR series product of BASF company and an ABCOMA L OTADER AX8900 product of France, the lubricant is an OptiPak series lubricant and a TPW series lubricant, and the antioxidant is hindered phenol and phosphite ester.

Further describing the technical scheme, the plant wood powder in the step (1) is fiber powder obtained by removing outer bast fibers from fruit trees, peach trees, poplar trees, willow trees, pear trees, hemp and flax, and the particle size of the wood powder is 80-400 meshes.

In the further description of the technical scheme, the biosurfactant is one of rhamnolipid, trehalose glycolipid, mannosylerythritol lipid and sophorolipid.

Further describing the technical scheme, the silane coupling agent in the step (3) is an epoxy silane coupling agent, the organically modified montmorillonite is montmorillonite subjected to organic modification treatment, and the citric acid lubricant comprises one or more of triethyl citrate, tri-n-butyl citrate, tri-n-octyl citrate and tristearic citrate.

Further describing the technical scheme, the stearic acid lubricating plasticizer in the step (4) comprises any one or a combination of pentaerythritol tetrastearate, trimethylolpropane tristearate and stearate.

On the basis, silane coupling agent developed and mature in the market is taken as modifier, and modified montmorillonite which is abundant in nature is taken as dispersant and intensifier of the wood flour, lubricating dispersant is added to prepare primarily dispersed and modified plant wood flour/montmorillonite mixed filler, and the enhancement and crystallization nucleation of the modified montmorillonite on P L A are kept while the effective dispersion of the wood flour is promoted, then, biological PBAT with good ductility and toughness is taken as a matrix of resin, and a degradable PBAT-co-P L A copolymer is taken as compatilizer to prepare dispersed mixed filler master batches, so that the dispersion and toughening are realized.

The invention provides a wood powder modification treatment technology and a preparation method of a plant wood powder/montmorillonite filled full-biodegradable polylactic acid composite material. Through the swelling of urea and the wetting and permeating action of the surfactant, the treatment efficiency of the biological enzyme is improved, and the cellulose structure is not greatly damaged. The wood powder is blended with clay, pre-dispersed in PBAT and a copolymer, and modified by chain extension of a chain extension active agent in the melt blending process, so that the dispersion effect of the wood powder and the compatibility of the wood powder and polylactic resin are improved. The wood powder treatment process is green and environment-friendly, the filler is natural, the resin can be fully biodegradable, the use of a non-degradable macromolecular compatilizer and a toughening agent is avoided, and the obtained polylactic acid composite material has good processability, strength and toughness. The method conforms to the economic development strategies of resource saving, circular economy, ecological civilization and the like proposed by the nation.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments