CN110746635A - A kind of composite starch foaming microbeads and preparation method thereof - Google Patents

Abstract

The invention discloses a composite starch foaming microbead and a preparation method thereof. According to the invention, the chemical foaming agent is added into the thermoplastic starch material and prepared into micro-particles, and then a layer of fully-degradable plastic film is coated outside the thermoplastic starch material to form the controllable foaming micro-beads, so that the preparation method can be widely applied to preparation of the full-starch or starch-based foaming composite material, and the production process is stable and controllable.

Description

A kind of composite starch foaming microbeads and preparation method thereof

technical field

The invention relates to the technical field of foaming materials, and more particularly, to a composite starch foaming microbead and a preparation method thereof.

Background technique

Starch is a renewable and recyclable green material from natural plants. It can not only be used as food for human consumption, but also widely used in the fields of chemical industry and new materials to prepare various composite materials. Because of its excellent biodegradability, starch is usually used as filler to prepare thermoplastic high biocarbon content bio-based composites, which are widely used in disposable products. people's attention. Using starch as raw material to prepare thermoplastic composite materials, because of the high density of starch, the comprehensive density of plasticized and compacted composite materials can reach about 1.4g/cm3, which has no advantages in transportation and material cost accounting compared with plastic materials. It is necessary to foam the starch-based composite materials to prepare composite foamed materials with a density similar to or lower than that of traditional plastics, which can greatly expand the application of starch-based composite materials and replace traditional plastics in more fields. It is of great significance to alleviate plastic pollution.

At present, there are generally two methods for foaming design of starch-based composite materials. One is to add chemical foaming agents, that is, adding AC and other chemical foaming agents to the formula of homogenized starch-based composite materials. During the molding process The chemical foaming agent is heated to decompose to release gas and evenly disperse in the composite material. The gas develops into bubbles under the action of the nucleating agent, and forms pores inside the composite material, thereby forming a foamed material with a cell structure. The technology is mainly used in the injection molding process. Another process is physical foaming, that is, during the molding process of the molten starch-based composite material, supercritical carbon dioxide or other types of gas are forced into the melt, and the gas is uniformly distributed under the action of external force shearing or stirring. Inside the melt of the composite material, and rapidly develop into bubbles, forming cells inside the composite material. However, these two processes have very high requirements on the deployment of molding equipment and material formulations, the production process is not easy to control, and cannot be realized for materials with low matrix melt strength. It is very necessary to design a more simple and controllable foaming process and method to prepare low-density starch-based composites.

SUMMARY OF THE INVENTION

The purpose of the present invention is to aim at the deficiencies in the prior art, and to provide a composite starch foaming microbead with low density, which can replace traditional plastics.

Another object of the present invention is to provide a method for preparing the above-mentioned composite starch foamed microbeads.

The object of the present invention is achieved through the following technical solutions:

A composite starch foaming microbead comprises a starch foaming matrix and a fully degradable plastic film, the starch foaming body is located in the center of the microbead, and the fully degradable plastic film is wrapped on the outside of the foaming matrix.

Further, the starch foaming matrix includes thermoplastic starch and foaming agent.

Further, the foaming agent is at least one of tosyl hydrazide and azocarboxamide.

Further, the fully degradable plastic film is at least one of PLA, PBAT or PBS.

A preparation method of the above-mentioned composite starch foaming microbeads, comprising the following steps:

S1. The thermoplastic starch and the foaming agent are mixed at a high speed and then kneaded evenly to obtain a starch foaming matrix;

S2. The kneaded starch foamed matrix is kneaded and granulated into spherical particles in a granulator to obtain foamed matrix particles;

S3. Spray the melted degradable plastic film melt to the foamed substrate, and stir at a high speed until the surface of the foamed substrate is evenly coated with a layer of fully degradable plastic film to obtain composite starch foamed microbeads.

Further, the kneading temperature in step S1 is 100-140°C.

Further, the particle size of the foamed matrix particles in step S2 is 0.2-0.3 mm.

Compared with the prior art, the beneficial effects of the present invention are as follows:

In the present invention, chemical foaming agent is added into thermoplastic starch material and prepared into micro-particles, and then a layer of fully degradable plastic film is coated on the outside to form controllable foaming micro-beads, which can be widely used in whole starch or starch-based hair In the preparation of the foamed composite material, the diameter of the microbead particles is 0.3-0.8 mm, and the density of the prepared foamed composite material can reach 0.8-1.1 g/cm ³ .

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1

The present embodiment provides a preparation method of composite starch foaming microbeads, comprising the following steps:

S1. Mix thermoplastic starch and tosyl hydrazide at a high speed, the amount of tosyl hydrazide is 2% of the amount of thermoplastic starch, and the mixture is uniformly mixed at 120 ° C to obtain a starch foaming matrix;

S2. The kneaded starch foamed matrix is kneaded and granulated into spherical particles of 0.3 mm in a granulator to obtain foamed matrix particles;

S3. Spray the molten PLA melt to the foamed substrate, and stir at a high speed until the surface of the foamed substrate is evenly coated with a layer of fully degradable plastic film to obtain composite starch foamed microbeads.

The microbeads prepared in this example have a particle size of 0.6 mm and a density of 1.0 g/cm ³ .

Example 2

The present embodiment provides a preparation method of composite starch foaming microbeads, comprising the following steps:

S1. Mix thermoplastic starch and tosyl hydrazide at a high speed, and the amount of tosyl hydrazide is 4% of the amount of thermoplastic starch, and knead uniformly at 140 ° C to obtain a starch foaming matrix;

S2. The kneaded starch foamed matrix is kneaded and granulated into spherical particles of 0.2 mm in a granulator to obtain foamed matrix particles;

S3. Spray the molten PBS melt to the foamed substrate, and stir at a high speed until the surface of the foamed substrate is evenly coated with a layer of fully degradable plastic film to obtain composite starch foamed microbeads.

The microbeads prepared in this example have a particle size of 0.8 mm and a density of 1.0 g/cm ³ .

Example 3

The present embodiment provides a preparation method of composite starch foaming microbeads, comprising the following steps:

S1. Mix thermoplastic starch, azoformamide and tosylhydrazide at high speed, wherein the amount of azoformamide is 2% of the amount of thermoplastic starch, and the amount of tosylhydrazide is 1% of the amount of thermoplastic starch, at 100°C The lower mixing is uniform to obtain a starch foaming matrix;

S2. The kneaded starch foamed matrix is kneaded and granulated into spherical particles of 0.2 mm in a granulator to obtain foamed matrix particles;

S3. The molten PBAT melt is sprayed onto the foamed substrate, and stirred at a high speed until the surface of the foamed substrate is evenly coated with a layer of fully degradable plastic film to obtain composite starch foamed microbeads.

The microbeads prepared in this example have a particle size of 0.3 mm and a density of 0.8 g/cm ³ .

Example 4

The present embodiment provides a preparation method of composite starch foaming microbeads, comprising the following steps:

S1. Mix thermoplastic starch and azoformamide at a high speed, and the amount of azoformamide is 5% of the amount of thermoplastic starch, and knead uniformly at 115 ° C to obtain a starch foaming matrix;

S2. The kneaded starch foamed matrix is kneaded and granulated into spherical particles of 0.3 mm in a granulator to obtain foamed matrix particles;

S3. The molten PLA and PBAT melts are sprayed onto the foamed substrate, and stirred at a high speed until the surface of the foamed substrate is evenly coated with a layer of fully degradable plastic film to obtain composite starch foamed microbeads.

The microbeads prepared in this example have a particle size of 0.5 mm and a density of 1.1 g/cm ³ .

Obviously, the above-mentioned embodiments are only examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (7)

1. a composite starch foaming microbead, is characterized in that, comprises starch foaming matrix and fully degradable plastic film, described starch foaming body is positioned at the center of microbead, and described fully degradable plastic film is wrapped outside the foaming matrix . 2 . The composite starch foaming microbeads according to claim 1 , wherein the starch foaming matrix comprises thermoplastic starch and a foaming agent. 3 . 3 . The composite starch foaming microbeads according to claim 2 , wherein the foaming agent is at least one of tosyl hydrazide and azocarboxamide. 4 . 4 . The composite starch foamed microbeads according to claim 1 , wherein the fully degradable plastic film is at least one of PLA, PBAT or PBS. 5 . 5. the preparation method of the composite starch foaming microbeads described in any one of claim 1～4, is characterized in that, comprises the following steps: S1. Mix the thermoplastic starch and the foaming agent at a high speed and then mix them evenly to obtain a starch foaming matrix; S2. The kneaded starch foamed matrix is kneaded and granulated into spherical particles in a granulator to obtain foamed matrix particles; S3. Spray the melted degradable plastic film melt to the foamed substrate, and stir at a high speed until the surface of the foamed substrate is evenly coated with a layer of fully degradable plastic film to obtain composite starch foamed microbeads. 6 . The preparation method according to claim 5 , wherein the mixing temperature in step S1 is 100-140° C. 7 . 7 . The preparation method according to claim 5 , wherein the particle size of the foamed matrix particles in step S2 is 0.2 to 0.3 mm. 8 .