CN-117070053-B - Method for improving dispersibility in process of preparing biodegradable plastic master batch from dry starch

Abstract

The invention belongs to the technical field of biodegradable plastics, and relates to a method for improving dispersibility in the process of preparing biodegradable plastic master batch from dry starch. Adding edible oil into dry starch with water content lower than 6%, mixing in a high-speed mixer, adding PLA or PBTA particles, continuously mixing in the high-speed mixer, and extruding and granulating by an extruder to obtain biodegradable plastic master batch with uniform texture. The dry starch can be directly mixed with PLA or PBAT after being added with edible oil as a dispersing agent, the processing process is simple, the phenomenon of starch aggregation is overcome, the starch addition amount can reach 70%, the use amount of PLA or PBAT is reduced, and the material cost is low. The problem of plasticizer precipitation does not exist, and the tensile strength, the tearing strength, the elongation, the impact toughness and the like of the product are obviously improved.

Inventors

• LIU YIFAN

Assignees

• 山东羽时生物科技有限公司

Dates

Publication Date

20260505

Application Date

20220509

Claims (3)

1. 1. A method for improving the dispersibility of dry starch in PBAT plastics comprising the steps of: uniformly mixing biological grease and PBAT granules in a mixer; adding dry starch into a mixer for continuous mixing until the dry starch is uniform to obtain a mixture; adding the mixture into a plastic processing machine for melt processing to obtain starch and PBAT alloy with uniform structure; Wherein, the dry starch accounts for 10-70% of the mass of the alloy, and the biological grease accounts for 2-10% of the mass of the dry starch; The moisture content of the dry starch is lower than 6%; The biological grease is one or more of vegetable grease, modified grease thereof, animal grease and modified grease thereof.
2. 2. The method for improving the dispersibility of dry starch in PBAT plastics according to claim 1, wherein the dry starch is prepared by taking semi-wet starch with a water content of 15-30 wt% in the wet milling starch processing procedure, or Mixing water with commercially available starch to obtain semi-wet starch with water content of 15-30 wt%; And (3) puffing in a puffing machine to obtain a starch puffed body, and then drying and crushing the starch puffed body to obtain the dry starch with the water content lower than 6%.
3. 3. The method for improving the dispersibility of dry starch in PBAT plastics according to claim 1, wherein the dry starch is added in an amount of 50 to 70% by weight of the mixture.

Description

Method for improving dispersibility in process of preparing biodegradable plastic master batch from dry starch Technical Field The invention belongs to the technical field of biodegradable plastics, and relates to a method for improving dispersibility in the process of preparing biodegradable plastic master batch from dry starch. Background With the increasing environmental awareness and the related national policy requirements in terms of environmental protection, many packaging materials such as supermarket plastic bags, takeaway cutlery boxes and the like require the use of biodegradable plastics for the plastics industry. The most common biodegradable plastics on the market at present are mainly polylactic acid (PLA), dibasic acid and dihydric alcohol copolyester (PBAT). The two materials have high cost, and the processability of the two materials is poor due to the properties of the two materials, so that a large proportion of filler is often added in the practical application process, the performance of the two materials is improved, and the raw material cost of the biodegradable plastic master batch is reduced. The most commonly used filler of PLA and PBTA is calcium carbonate at present, and the calcium carbonate is an inorganic substance, so that natural biodegradation of the calcium carbonate is difficult to realize in nature. More desirable fillers for PLA and PBTA are starches, and much research is currently directed to the use of starches in biodegradable plastics. At present, the application of starch in biodegradable plastics mainly has the technical barriers that firstly, the starch has the characteristics of poor plasticity and difficult molding due to the property of the starch, and has no mechanical property and service performance of the traditional plastics, secondly, about 30 percent of glycerol needs to be added in the process of adding the starch as a filler into a plastic master batch, the later precipitation of the glycerol can cause the viscosity of the master batch to be increased so as to influence the subsequent processing and use, thirdly, the water content in the current commercial starch is higher, generally about 13 percent, and the time is long after the commercial starch is added into the degradable plastic master batch, the water content is slowly precipitated, the retrogradation of the starch can cause the brittleness of the degradable plastic product, and the mechanical property is reduced. The patent application number 2021114585542 describes a preparation process of low-water content dry starch, and plastic master batches prepared from the dry starch can solve the problem that starch plastic products become brittle after aging, but researchers find that during the processing process, the dry starch can be agglomerated when combined with PABT, and the agglomerated particles can cause the problems that subsequent processing cannot be carried out, the internal tissue uniformity of the final product is reduced, and the product cannot be used. At present, no document or patent report is available for solving the problem of the dry starch and the PBAT alloy during the processing process. Disclosure of Invention The invention provides a method for improving dispersibility of dry starch in PBAT plastic, aiming at the problem of agglomeration of dry starch in the using process. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: a method of improving the dispersibility of dry starch in PBAT plastics comprising the steps of: (1) Firstly, uniformly mixing biological grease and PBAT granules in a mixer; (2) Adding the dry starch into a mixer for continuous uniform mixing to obtain a mixture; (3) And adding the mixture into a plastic processing machine for melt processing to obtain the starch and PBAT alloy with uniform tissues. Wherein, the dry starch accounts for 10-70% of the mass of the alloy, and the biological grease accounts for 2-10% of the mass of the dry starch. Preferably, the biological oil is one or a combination of vegetable oil and modified oil thereof, animal oil and modified oil thereof. Preferably, the dry starch is prepared by taking semi-wet starch with water content of 15-30wt% in wet grinding starch processing procedure, or Mixing water with commercial starch to obtain semi-wet starch with water content of 15-30 wt%, puffing to obtain starch puffed body, drying, and pulverizing to obtain dry starch with water content of less than 6%. Preferably, it is characterized in that the dry starch is added in an amount of 50-70% by weight of the masterbatch. The basic principle of the invention is as follows: Firstly, the technical problem of dry starch in use can be solved, and the phenomenon of agglomeration is weakened or even eliminated. In addition, the phenomenon of 'agglomeration' of the dry starch and the PBAT alloy is serious along with the increase of the dry starch content in the forming process, when