阅读说明：本技术 一种可降解增强型塑料及其制备方法 (Degradable reinforced plastic and preparation method thereof ) 是由 杨春云 于 2020-06-01 设计创作，主要内容包括：本发明属于高分子材料技术领域,具体涉及一种可降解增强型塑料及其制备方法。所述塑料包括以下重量份数的组分：天然淀粉45～60％、增塑剂1～5％、聚乙烯醇5～15％、聚乳酸10～20％、改性凹凸棒石1～8％和添加剂3～10％。本发明提供的可降解增强型塑料具有良好的热稳定性和力学性能,且降解性能较好,可应用于制备购物袋、垃圾袋、一次性餐盒等,对环境污染小,具有良好的环境效益。(The invention belongs to the technical field of high polymer materials, and particularly relates to degradable reinforced plastic and a preparation method thereof. The plastic comprises the following components in parts by weight: 45-60% of natural starch, 1-5% of plasticizer, 5-15% of polyvinyl alcohol, 10-20% of polylactic acid, 1-8% of modified attapulgite and 3-10% of additive. The degradable reinforced plastic provided by the invention has good thermal stability and mechanical property, and good degradation property, can be applied to preparation of shopping bags, garbage bags, disposable lunch boxes and the like, has little pollution to the environment, and has good environmental benefit.)

1. The degradable reinforced plastic is characterized by comprising the following components in parts by weight: 45-60% of natural starch, 1-5% of plasticizer, 5-15% of polyvinyl alcohol, 10-20% of polylactic acid, 1-8% of modified attapulgite and 3-10% of additive.

2. The degradable reinforced plastic of claim 1, wherein the native starch is selected from at least one of corn starch, wheat starch, and tapioca starch.

3. The degradable reinforced plastic of claim 1, wherein the plasticizer is one or more selected from the group consisting of glycerin, sorbitol, xylitol, maltitol, polyethylene glycol, and urea.

4. The degradable reinforced plastic of claim 1, wherein the modified attapulgite is prepared by intercalation modification of attapulgite with hydrophobic starch as a modifier.

5. The degradable reinforced plastic of claim 4, wherein the modification comprises the following specific steps:

uniformly dispersing attapulgite in 30-50% ethanol solution, adding 1-3% epoxy chloropropane and hydrophobic starch, reacting at 60-80 ℃ for 3-4 h, evaporating the solvent to dryness, drying the reaction product, and grinding to obtain the attapulgite modified attapulgite.

6. The degradable reinforced plastic of claim 5, wherein the weight ratio of the hydrophobic starch to the attapulgite is 5: 1-3.

7. The degradable reinforced plastic of claim 4, wherein the attapulgite is pretreated by high temperature activation before being modified by intercalation.

8. The degradable reinforced plastic of claim 7, wherein the high temperature activation pretreatment step is: heating the crucible to 350-400 ℃, then adding attapulgite, preserving the heat for 1-5 min, and naturally cooling.

9. The degradable reinforced plastic of claim 1, wherein the additive is at least one selected from the group consisting of lubricants, flow promoters, and degradation promoters.

10. The method for manufacturing the degradable reinforced plastic as claimed in any one of claims 1 to 9, wherein the manufacturing method comprises the following steps: adding the raw materials into a high-speed mixer, fully and uniformly mixing, blending and compounding by using a double-screw extruder, and then extruding, cooling and granulating to obtain the degradable reinforced plastic.

Technical Field

The invention belongs to the technical field of macromolecules. More particularly, it relates to a degradable reinforced plastic and its preparation method.

Background

Starch is widely applied to the main raw material for preparing environment-friendly degradable plastics at present, and the starch-based degradable plastics are the most promising biodegradable plastics capable of replacing petroleum-based plastics at present. However, the hydrophilicity of starch itself causes the starch-based plastic to have the defects of thermal property, water resistance and mechanical property.

Aiming at the defects of the thermal property of starch-based plastics, the most researches are to improve the thermal stability and the melt processing function of starch by adding inorganic fillers such as montmorillonite, kaolinite, carbon nano tube and the like. For example, Nistor and the like adopt trimethyl dodecyl ammonium ions to modify montmorillonite, and the montmorillonite is added into a TPS/PVA composite material, so that the decomposition temperatures of 5 percent and 50 percent of weight loss of the composite material are respectively increased by 2.6 ℃ and 2.1 DEG C^[1](ii) a Kaewtatip K, Tanrataakul V and the like research the influence of kaolinite on the thermal stability of TPS composite materials, and find that the decomposition temperatures of the composite materials added with 10%, 30% and 60% of kaolinite are 336 ℃, 339 ℃ and 342 ℃ respectively, and the addition amount of the kaolinite and the thermal stability of the composite materials are in positive correlation^[2]. However, since the inorganic fillers have a small particle size and a high surface energy, they have poor compatibility with the starch matrix, are easily agglomerated, and are difficult to be uniformly dispersed in the starch matrix. Thus, the key to the current application of inorganic fillers to starch-based composites is to improve the dispersibility and compatibility of the inorganic filler in the starch matrix.

Attapulgite, also known as Attapulgite (Attapulgite), is a crystalline hydrous magnesium aluminum silicate clay mineral with a 2:1 lamellar crystal structure. At present, researches show that the strength of plastics can be enhanced by using the natural attapulgite in the plastics, and the attapulgite can promote the crystallization speed of the plastics in the injection molding process, modulate the crystal structure of the plastics and play a role of a nucleating agent. However, no report is available for modifying the starch-based plastic and improving the strength and the heat stability of the starch-based plastic.

Reference documents:

[1]Nistor M，Vasile C，Iran Polym J,2013,22:519～536；

[2]Kaewtatip K，Tanrattanakul V.Mater Design，2012,37:423～428。

disclosure of Invention

The invention aims to solve the technical problems that the existing starch-based plastic is poor in strength and thermal stability, and a reinforcing agent is difficult to disperse uniformly in a starch system, and provides a degradable reinforced plastic and a preparation method thereof.

The invention aims to provide a degradable reinforced plastic which comprises the following components in parts by weight: 45-60% of natural starch, 1-5% of plasticizer, 5-15% of polyvinyl alcohol, 10-20% of polylactic acid, 1-8% of modified attapulgite and 3-10% of additive.

Preferably, the starch is selected from at least one of corn starch, wheat starch and tapioca starch.

Preferably, the plasticizer is selected from one or more of glycerin, sorbitol, xylitol, maltitol, polyethylene glycol and urea. In one embodiment of the invention, the plasticizer is prepared by compounding glycerol and polyethylene glycol, and the compounded plasticizer can obtain a better plasticizing effect.

Preferably, the modified attapulgite is prepared by taking hydrophobic starch as a modifier and carrying out intercalation modification on the attapulgite.

The addition of the same content of the natural attapulgite can play a role in increasing the strength of the material, but the thermal stability of the material is reduced because the natural attapulgite acts as a nucleating agent in a material system, the formation of starch crystals is promoted, the initial decomposition temperature and the melting temperature of the material are reduced, and the effect becomes more obvious with the increase of the addition amount of the natural attapulgite.

In order to improve the performance of the attapulgite, increase the strength of the attapulgite and simultaneously not reduce or even improve the thermal stability of a starch-based plastic system, the inventor of the invention surprisingly finds that the performance of the attapulgite can be improved by adopting hydrophobic starch as a modifier to perform intercalation modification on the attapulgite.

Preferably, the attapulgite modification method comprises the following specific steps:

uniformly dispersing attapulgite in 30-50% ethanol solution, adding 1-3% epoxy chloropropane and hydrophobic starch, reacting at 60-80 ℃ for 3-4 h, evaporating the solvent to dryness, drying the reaction product, and grinding to obtain the attapulgite modified attapulgite.

Preferably, the weight ratio of the hydrophobic starch to the attapulgite is 5: 1-3.

Tests prove that the heat stability of the modified attapulgite material system is obviously improved, and the attapulgite modified by hydrophobic starch has good compatibility with a matrix due to the similarity of the polarity to the starch matrix, can be uniformly dispersed in the starch matrix, and has more remarkable effect of improving the thermal property and the mechanical property of the material; in addition, the attapulgite inserted with the hydrophobic starch has higher compatibility with polyvinyl alcohol and polylactic acid, and can be better combined with the polyvinyl alcohol and the polylactic acid.

Preferably, the attapulgite is pretreated by high-temperature activation before being modified by intercalation. In order to promote the formation of the peeling structure and enable hydrophobic starch molecular chains to be inserted into the silicate layer of the attapulgite more easily, the natural attapulgite is preferably subjected to high-temperature activation pretreatment before modification. Because the zeolite water and the crystal water are filled in the middle of the attapulgite layer structure channel, if the natural attapulgite is suddenly exposed to a high-temperature environment, the water among the attapulgite layer structures can be instantly vaporized into steam, and the interlayer distance of the attapulgite can be expanded by the steam, so that the starch can be more easily inserted into the attapulgite layer structure, thereby improving the intercalation efficiency.

Preferably, the high-temperature activation pretreatment step is as follows: heating the crucible to 350-400 ℃, then adding attapulgite, preserving the heat for 1-5 min, and naturally cooling.

The term "hydrophobic starch" as used herein refers broadly to a starch having a hydrophobic surface, and specifically in the present invention, a starch modified with trimethylethoxysilane, the specific modification steps being:

adding distilled water into starch to prepare 20-35% of starch milk by mass, stirring, heating to 40-60 ℃, adding anhydrous sodium sulfate accounting for 1-5% of the weight of the starch, preserving heat for 1-5 min, and adjusting the pH to 8.0-9.0 by adopting a sodium hydroxide solution with the concentration of 1-3%; slowly adding trimethylethoxysilane accounting for 3-8% of the weight of the starch, reacting for 1-4 h, and keeping the pH constant during the reaction; after the reaction is finished, adjusting the pH value to be neutral, and filtering, washing, drying and crushing a reaction product to obtain the hydrophobic starch.

The starch raw material adopted in the hydrophobic starch can be one of sweet potato starch, tapioca starch, corn starch and wheat starch. In one embodiment of the present invention, corn starch is preferred for improved compatibility with the starch matrix.

Preferably, the additive is selected from at least one of a lubricant, a flow promoter, and a degradation promoter. Wherein the preferable using amount of the lubricant is 1-3%; the preferable dosage of the flow promoter is 1-3%, and the preferable dosage of the degradation promoter is 1-5%. The lubricant includes, but is not limited to, polyethylene wax, paraffin wax, liquid wax, and polypropylene wax; the flow promoters include, but are not limited to span, glyceryl monostearate, and glucose fatty acid esters; the degradation promoters include, but are not limited to, citric acid, lactic acid, malic acid, quinic acid, succinic acid, ferric diammonium sulfate, ferric chloride, ferric acetylacetonate, cobalt nitrate, and ferric nitrate.

The invention also aims to provide a method for manufacturing the degradable reinforced plastic, which comprises the following steps: adding the raw materials into a high-speed mixer, fully and uniformly mixing, blending and compounding by using a double-screw extruder, and then extruding, cooling and granulating to obtain the degradable reinforced plastic.

The invention has the following beneficial effects:

1) the starch/polyvinyl alcohol/polylactic acid plastic provided by the invention is added with more starch, the plastic integrally shows better degradation performance, can be applied to preparation of shopping bags, garbage bags, disposable lunch boxes and the like, has little pollution to the environment, and has good environmental benefit.

2) The degradable reinforced plastic provided by the invention has the advantages that the heat performance and the mechanical property of the starch-based plastic are obviously improved by adding the specially modified attapulgite, and the degradable reinforced plastic has excellent tensile property and toughness.

3) According to the invention, the hydrophobic starch is inserted into the attapulgite, so that on one hand, the performance of the attapulgite is improved, the attapulgite has the effects of improving the thermal performance of the material and enhancing the strength of the material, and on the other hand, the compatibility between the attapulgite and a starch matrix, polyvinyl alcohol and polylactic acid is improved.

Detailed Description

The present invention is further illustrated by the following specific examples, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available.