阅读说明：本技术 一种生物降解淀粉塑料母料及制备方法 (Biodegradable starch plastic master batch and preparation method thereof ) 是由 陈庆 曾军堂 于 2019-10-11 设计创作，主要内容包括：本发明属于淀粉塑料的技术领域,具体涉及一种生物降解淀粉塑料母料及制备方法。本发明通过辅助无机粉末,通过淀粉细化,导致淀粉颗粒结构发生改变,分子呈无序化状态,有效防止细化、无序化的淀粉重新结晶,同时添加顺酐,使淀粉的结晶结构被破坏,降低了使用极性材料增塑淀粉造成的耐热性变差等问题,得到的淀粉结晶度低,而且不容易再结晶,可以直接当作普通的填料与基础树脂混炼造粒,且与树脂相容性得到大大提升。(The invention belongs to the technical field of starch plastics, and particularly relates to a biodegradable starch plastic master batch and a preparation method thereof. According to the invention, the starch particle structure is changed through the auxiliary inorganic powder and the starch is refined, the molecules are in a disordered state, the refined and disordered starch is effectively prevented from being recrystallized, the crystalline structure of the starch is damaged by adding the maleic anhydride, the problems of poor heat resistance and the like caused by using polar material plasticized starch are reduced, the obtained starch has low crystallinity and is difficult to recrystallize, the starch can be directly used as a common filler to be mixed and granulated with the base resin, and the compatibility with the resin is greatly improved.)

1. A preparation method of biodegradable starch plastic master batch is characterized by comprising the following steps:

(1) adding starch and inorganic powder into a high-speed mixer according to the mass ratio of 3:1, then adding a hydrophobic modifier, heating to 100-;

(2) adding the mixture into a jet mill, controlling the rotation speed of a rotor to be 800-1200rpm, controlling the rotation speed of a grader to be 1800rpm, stabilizing the temperature of a milling chamber of the jet mill to be 80-90 ℃, modifying through jet milling to continuously refine the starch and enable the structure of the starch to be disordered and amorphous, esterifying the refined starch by maleic anhydride, replacing hydroxyl of the starch by the open loop of the maleic anhydride, and further breaking the crystalline structure of the starch to obtain the refined thermoplastic starch;

(3) 70-85 parts of thermoplastic starch, 3-5 parts of white oil, 1-1.5 parts of aluminate coupling agent, 0.01-0.02 part of dicumyl peroxide and 10-15 parts of base resin are uniformly mixed in a high-speed mixer, and are subjected to reaction extrusion granulation at the temperature of 150-165 ℃ by a meshing type double-screw extruder to obtain the biodegradable starch plastic master batch.

2. The method for preparing biodegradable starch plastic masterbatch according to claim 1, wherein the starch is at least one of corn starch, pea starch and tapioca starch.

3. The method for preparing a biodegradable starch plastic masterbatch according to claim 1, wherein the inorganic powder is at least one of talc powder, mica powder, calcium carbonate powder, wollastonite powder, kaolin, montmorillonite, quartz powder, white carbon black powder, barium sulfate powder and glass powder.

4. The method for preparing the biodegradable starch plastic master batch according to claim 1, wherein the hydrophobic modifier is at least one of polyethylene wax, paraffin wax and stearic acid; the addition amount is 5-8% of the total mass of the starch and the inorganic powder.

5. The method for preparing biodegradable starch plastic masterbatch according to claim 1, wherein the amount of maleic anhydride added is 0.5-2% of the total mass of starch and inorganic powder.

6. The method for preparing a biodegradable starch plastic master batch as claimed in claim 1, wherein the base resin is a resin with excellent fluidity at 150 ℃.

7. The method for preparing biodegradable starch plastic masterbatch according to claim 1, wherein the base resin is at least one of EVA33-400, LD400, and 1I 50A.

8. The biodegradable starch plastic masterbatch prepared by the method for preparing biodegradable starch plastic masterbatch of any one of claims 1-7.

Technical Field

The invention belongs to the technical field of starch plastics, and particularly relates to a biodegradable starch plastic master batch and a preparation method thereof.

Background

Nowadays, the development of low-carbon economy becomes a global trend, and the development of the low-carbon economy is used as a fundamental way for coordinating, protecting global climate and promoting the development of domestic economy. If the biomass resources are utilized to replace high polymer plastics by the biological materials produced by the industrial biotechnology process, hundreds of millions of tons of CO2 net emission reduction can be realized; according to the data of European bioplastic society, the emission of CO2 can be reduced by 0.8-3.2 t when 1t of starch-based plastic is used, so that the bioplastic plays an important role in low-carbon economy. Since the 21 st century, the global environment is protected, a resource circulation type society is constructed, a sustainable development road is formed, and the global focus and urgent tasks are formed.

The life cycle of the biological starch plastic products can be continuously circulated, belongs to a typical environment low-load material, and therefore, the biological starch plastic products become hot spots of global research and development. Especially, starch-based biodegradable plastics have wide market prospect on the low-carbon economy road from the aspects of product price, performance, industrial scale, market application and the like.

In general, biodegradable plastics, also called starch-based biodegradable plastics, are prepared by blending natural high molecular starch into a polymer resin. Because the structure, polarity, solubility parameter and the like of the natural starch and the polyethylene are different greatly, from the thermodynamic and colloid chemistry viewpoints, the natural starch is a polyhydroxy compound, the polarity of the polyhydroxy compound is very large, the polarity of the polyethylene is very small, the affinity and the compatibility of the polyhydroxy compound and the polyethylene are low, a homogeneous system with molecular compatibility cannot be obtained, the dispersion degree of the starch in the resin is very low, and the filling amount is very small; in addition, starch does not have thermoplastic characteristics, and excessive use of starch causes difficulties in thermoplastic processing, easy scorching, incapability of secondary processing and the like, thereby influencing the application of starch in the field of plastic processing.

The starch granules contain amylose and amylopectin and can form a three-dimensional semi-crystalline gel network structure. The starch structure disorder and non-crystallization are beneficial to the improvement of thermoplasticity, and at present, the technology for solving the thermoplasticity of the starch mainly adopts polar micromolecular materials for plasticization; starch graft copolymerization, starch refinement and the like.

The Chinese patent application No. 201810578164.0 discloses a biodegradable plastic master batch and a preparation method thereof, wherein the master batch comprises the following raw materials: starch, polypropylene carbonate, polyhydroxybutyrate valerate, magnesium stearate, epoxidized soybean oil, glycerol, hexamethylene diisocyanate, 2-phenyl-2-oxazoline, a lubricant, a styrene-butadiene-styrene block copolymer, 1, 3-dimethyl-6-semicarbazide pyrimidine, N' -bis (2, 6-diisopropylphenyl) carbodiimide, dioctadecyl pentaerythritol diphosphite, cerium stearate, phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, potassium chloride, lauric acid diethanolamide borate. Is a master batch which can be rapidly degraded by enzyme secreted by microorganisms in a short time.

The Chinese patent application No. 201910127286.2 discloses a method for producing biodegradable starch-based master batch, which comprises the following steps: (1) mixing and stirring starch and vinyl acetate-ethylene copolymer emulsion (VAE) at the temperature of between 40 and 70 ℃, wherein the mass of the VAE emulsion is 30 to 70 percent of that of the starch; (2) cooling the material obtained in the step 1 to room temperature and crushing the material into powder; (3) mixing the material obtained in the step (2) with powdery calcium carbonate, wherein the mass of the calcium carbonate is 1-7 times that of the starch in the step (1); (4) and (4) extruding and granulating the material in the step (3) through a screw machine.

The polar small molecule plasticizing is most obvious, such as glycerol, glycol and the like, which obviously improves the thermoplasticity of the starch, but the heat resistance of the starch is deteriorated due to the use of a large amount of polar plasticizer, and the compatibility with common plastics and the heat processing difficulty are caused by the use of excessive polar plasticizer. In particular, the use of a large amount of polar plasticizer causes the starch plastic to have poor strength and water resistance, and is usually expressed by the precipitation of the plasticizer; starch graft copolymerization has high process requirements and complex reaction, which leads to high cost; starch refinement is a plasticizing process that is easy to implement and does not affect the hot workability of the starch. The thinning of the starch can change starch molecules, such as molecular chain micro-breakage, end group generation of electronic effect, specific surface area increase, molecular overall structure relaxation, crystallinity reduction, molecular weight reduction and the like, so that the disordering degree of the starch is increased, and the amorphization is obvious. Refined starch has been shown to have excellent effects in starch plastics. In the thinning process of the starch, on one hand, the cost is increased along with the reduction of the fineness of the starch; on the other hand, the refined starch has the problems of agglomeration and regeneration crystallization.

Disclosure of Invention

Aiming at the defects that the heat resistance is poor after polar micromolecule thermoplastic treatment is adopted to treat starch, high temperature is difficult to bear when the starch is processed in plastic processing equipment and the problems that the starch after the polar micromolecule thermoplastic treatment is difficult to be compatible with common non-polar resin for thermoplastic processing, the invention provides a biodegradable starch plastic master batch and a preparation method thereof for further large-scale popularization of the processing application of starch-based plastics.

In order to realize the purpose, the following technical scheme is adopted:

a preparation method of biodegradable starch plastic master batch comprises the following specific preparation processes:

(1) adding starch and inorganic powder into a high-speed mixer according to the mass ratio of 3:1, then adding a hydrophobic modifier, heating to 100-;

(2) adding the mixture into a jet mill, controlling the rotation speed of a rotor to be 800-1200rpm, controlling the rotation speed of a grader to be 1800rpm, stabilizing the temperature of a milling chamber of the jet mill to be 80-90 ℃, modifying through jet milling to continuously refine the starch and enable the structure of the starch to be disordered and amorphous, esterifying the refined starch by maleic anhydride, replacing hydroxyl of the starch by the open loop of the maleic anhydride, and further breaking the crystalline structure of the starch to obtain the refined thermoplastic starch;

(3) 70-85 parts of thermoplastic starch, 3-5 parts of white oil, 1-1.5 parts of aluminate coupling agent, 0.01-0.02 part of dicumyl peroxide and 10-15 parts of base resin are uniformly mixed in a high-speed mixer, and are subjected to reaction extrusion granulation at the temperature of 150-165 ℃ by a meshing type double-screw extruder to obtain the biodegradable starch plastic master batch.

Further, the starch is at least one of corn starch, pea starch and cassava starch.

Further, the inorganic powder is at least one of talcum powder, mica powder, calcium carbonate powder, wollastonite powder, kaolin, montmorillonite, quartz powder, white carbon black powder, barium sulfate powder and glass powder.

Further, the hydrophobic modifier is at least one of polyethylene wax, paraffin and stearic acid; the addition amount is 5-8% of the total mass of the starch and the inorganic powder.

Further, the addition amount of the maleic anhydride is 0.5-2% of the total mass of the starch and the inorganic powder. Maleic anhydride, also known as maleic anhydride, 2, 5-furandione, etc., has a strong pungent smell, is colorless in an orthorhombic system, is needle-like or sheet-like, is soluble in ethanol, diethyl ether and acetone, and is insoluble in petroleum ether and carbon tetrachloride. Reacting with hot water to obtain maleic acid.

Further, the base resin is selected from resins having excellent fluidity at 150 ℃.

Further preferably, the base resin is at least one of EVA33-400, LD400 and 1I 50A.

Further, the meshed double-screw extruder is a co-rotating double-screw extruder and is provided with a vacuum exhaust hole; the equipment has a high shearing effect, the base resin is melted under the shearing and high temperature effects of the screw, and the grafting reaction of the starch is further carried out under the screw extrusion condition; meanwhile, dicumyl peroxide partially crosslinks the base resin, and when maleic anhydride is present, the uncrosslinked base resin contains maleic anhydride side groups to form grafts, and the presence of the grafts endows the base resin with certain polarity, thereby promoting better compatibility with the esterified starch.

Further, the invention provides a biodegradable starch plastic master batch prepared by the method. It is known that the thermoplastic treatment of starch is usually carried out by treating with polar small molecular materials such as glycerol, ethylene glycol and the like, which is obvious for improving the thermoplastic property of starch, but the heat resistance of starch is deteriorated due to the use of a large amount of polar plasticizer, and the compatibility with common plastics and the heat processing difficulty are caused by the use of excessive polar plasticizer. In particular, the use of a large amount of polar plasticizer results in deterioration of strength and water resistance of the starch plastic. Often manifested as plasticizer bleed-out, affecting the plastic article. The invention leads the structure of starch granules to be changed and molecules to be in a disordered state by the auxiliary inorganic powder and the starch refinement, and effectively prevents the refined and disordered starch from being recrystallized due to the auxiliary inorganic powder; meanwhile, micronized starch is esterified by maleic anhydride under the action of mechanochemistry, and hydroxyl of the starch is replaced by the open loop of the maleic anhydride, so that the crystalline structure of the starch is further destroyed, and the refined thermoplastic starch is obtained; the processing method reduces the negative effects caused by using a large amount of polar materials to plasticize starch, the obtained starch has low crystallinity and is difficult to recrystallize, and the starch can be directly used as a common filler to be mixed and granulated with base resin, so that the large-scale stable preparation technology of starch plastics is greatly improved. In addition, when the screw is extruded, the partial maleic anhydride is further promoted to be grafted with the base resin by adding the cross-linking agent, so that the compatibility with the thermoplastic starch is increased.

Has the advantages that:

the invention relates to a biodegradable starch plastic master batch and a preparation method thereof, which can effectively prevent refined and disordered starch from recrystallizing by thinning starch through auxiliary inorganic powder, simultaneously, the addition of maleic anhydride can destroy the crystal structure of the starch, reduce the problems of poor heat resistance and the like caused by using polar material plasticized starch, and the obtained starch has low crystallinity and is not easy to recrystallize, can be directly used as a common filler to be mixed and granulated with base resin, and greatly improves the compatibility with the resin.

Drawings

FIG. 1: example 1 polarization microscope observation picture.

FIG. 2: comparative example 1 polarization microscope observation image.

FIG. 3: comparative example 2 polarization microscope observation image.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, but it should not be construed that the scope of the present invention is limited to the following examples. Various substitutions and alterations can be made by those skilled in the art and by conventional means without departing from the spirit of the method of the invention described above.