阅读说明：本技术 一种淀粉基塑料餐具及其制备方法 (Starch-based plastic tableware and preparation method thereof ) 是由 祁海松 刘宏臣 张存智 党超 王明 冯晓 余杰 袁亚芳 于 2020-07-30 设计创作，主要内容包括：本发明涉及一种淀粉基塑料餐具及其制备方法。该方法包括：将干燥后的淀粉加入到溶剂中,加热溶解,冷却至室温得到淀粉溶液；在通入氮气保护条件下,将上述淀粉溶液加热至反应温度,滴加入乙酰乙酸叔丁酯,恒温反应,冷却至室温,提纯,真空干燥,得到乙酰乙酸淀粉酯；然后将乙酰乙酸淀粉酯加入挤出机中混合均匀,熔融挤出注入模具,冷却至室温即得样品。本发明提出的制备淀粉基塑料餐具的生产方法,工艺简单、操作安全、绿色环保,制备的淀粉基塑料餐具备优异的防水性、耐热性和良好的机械性能,是一种高质量的全降解环保产品。(The invention relates to starch-based plastic tableware and a preparation method thereof. The method comprises the following steps: adding the dried starch into a solvent, heating for dissolving, and cooling to room temperature to obtain a starch solution; under the condition of introducing nitrogen gas for protection, heating the starch solution to a reaction temperature, dropwise adding tert-butyl acetoacetate, reacting at a constant temperature, cooling to room temperature, purifying, and drying in vacuum to obtain starch acetoacetate; and then adding the acetoacetic acid starch ester into an extruder, uniformly mixing, melting, extruding, injecting into a mold, and cooling to room temperature to obtain the sample. The production method for preparing the starch-based plastic tableware provided by the invention has the advantages of simple process, safe operation, environmental protection, and excellent waterproofness, heat resistance and mechanical property, and is a high-quality fully-degradable environment-friendly product.)

1. The preparation method of the starch-based plastic tableware is characterized by comprising the following steps:

(1) vacuum drying starch, adding the starch into a solvent, heating for dissolving, uniformly dissolving, and cooling to room temperature to obtain a starch solution;

(2) heating the starch solution to a reaction temperature under the protection of nitrogen, dropwise adding tert-butyl acetoacetate, carrying out a constant temperature reaction, cooling to room temperature to obtain a reaction product, purifying, and carrying out vacuum drying to obtain starch acetoacetate;

(3) and (3) adding the starch acetoacetate in the step (2) into an extruder, uniformly mixing, melting, blending, extruding, injecting into a mold, and cooling to room temperature to obtain the starch-based plastic tableware.

2. The method for preparing starch-based plastic tableware according to claim 1, wherein the temperature of vacuum drying in step (1) is 60-80 ℃ and the time of vacuum drying is 12-24 h.

3. The method for preparing starch-based plastic tableware according to claim 1, wherein said starch of step (1) is one of corn starch, glutinous rice starch, tapioca starch, potato starch, rice starch, wheat starch, barley starch, acorn starch, sago starch, sweet potato starch, high amylose starch, pea starch; the solvent is more than one of dimethyl sulfoxide, an N, N-dimethylacetamide/lithium chloride system, N-dimethylformamide, pyridine, carbon tetrachloride, 1-ethyl-3-methylimidazole chloride salt, 1-ethyl-3-methylimidazole acetate, 1-allyl-3-methylimidazole chloride salt, 1-butyl-3-methylimidazole chloride salt and 1-butyl-3-methylimidazole dicyandiamide bromide salt.

4. The method for preparing starch-based plastic tableware according to claim 1, wherein the temperature for heating and dissolving in step (1) is 80-90 ℃ and the time for heating and dissolving is 0.5-2 h.

5. The method for preparing starch-based plastic tableware according to claim 1, wherein the mass-to-volume ratio of starch to solvent in step (1) is 20: 80g/mL-20:200 g/mL.

6. The method for preparing starch-based plastic tableware according to claim 1, wherein the isothermal reaction temperature in step (2) is 100 ℃ and 120 ℃, and the isothermal reaction time is 1-8 h.

7. The method for preparing starch-based plastic tableware according to claim 1, wherein said purifying of step (2) comprises: adding the reaction product into an ethanol solvent to separate out a precipitate, washing the precipitate by using the ethanol solvent, and performing suction filtration to obtain a purified reaction product; the temperature of the vacuum drying is 60-80 ℃, and the time of the vacuum drying is 12-24 h.

8. The method for preparing starch-based plastic tableware according to claim 1, wherein the molar ratio of the t-butyl acetoacetate in the step (2) to the starch in the step (1) is 2:1-8: 1.

9. The method for preparing starch-based plastic tableware according to claim 1, wherein the temperature for melt blending in step (3) is 120-180 ℃ and the time for melt blending is 5-20 min.

10. A starch-based plastic tableware obtainable by the process according to any one of claims 1 to 9.

Technical Field

The invention belongs to the field of degradable tableware preparation, and particularly relates to starch-based plastic tableware and a preparation method thereof.

Background

With the development of economy, the consumption of disposable tableware has been accelerated by the flourishing of the tourism and take-out industries. However, most disposable plastic products are discarded after the use function is completed, and most of the disposable plastic products are treated in a simple way of burning, burying or dumping, so that the recycling rate is low. In addition, the common disposable plastic tableware has the defect of difficult biodegradation, which brings serious environmental pollution and is difficult to develop for a long time. With the increasing awareness of environmental protection, countries around the world begin to pay more attention to the pollution of disposable plastic tableware products in daily life. The common plant fiber type and pulp type cellulose-based tableware mostly needs a series of complex processes of pulping, purifying, forming, drying, shaping, trimming and the like during preparation, and the prepared product is deficient in color, luster, appearance and quality stability and has large wastewater discharge. And polylactic acid plastic tableware has the problem of high price and low market acceptance.

Starch is a polysaccharide high molecular compound consisting of glucose, and has the characteristics of wide source, low price, good biocompatibility, easy biodegradation and the like. The original starch has poor toughness after film forming, is easy to brittle fracture when being bent, is not melted when being heated, brings certain difficulty to processing, and has the characteristic of poor stability when being prepared. In addition, starch contains a large number of hydroxyl groups in its molecular structure, which can be easily modified in a controlled manner to impart various functions (x.wang, l.huang, c.zhang, y.deng, p.xie, l.liu, j.cheng, Carbohydrate Polymers 2020,240,116292.). The development of the starch-based green environment-friendly tableware can reduce environmental pollution, replace the situation of meeting the human living necessities, and has good social value and profound practical significance.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide starch-based plastic tableware and a preparation method thereof.

The invention aims to solve the technical problem of providing a preparation method of starch-based plastic tableware, which adopts environment-friendly, abundant and cheap starch as a raw material to prepare esterified starch and adopts a melt blending extrusion method to prepare the starch-based plastic tableware. The starch-based plastic tableware has good waterproof performance, heat resistance and biodegradability; the preparation method provided by the invention has the advantages of simple process and rich raw materials, is suitable for modification of most of starch, and has good application prospect in the fields of takeaway, food packaging and the like due to good biocompatibility of the starch.

The purpose of the invention is realized by at least one of the following technical solutions.

The preparation method of the starch-based plastic tableware provided by the invention comprises the following steps:

(1) vacuum drying starch, adding the starch into a solvent, heating for dissolving, uniformly dissolving, and cooling to room temperature to obtain a starch solution;

(2) under the condition of nitrogen protection, heating the starch solution to a reaction temperature, dropwise adding tert-butyl acetoacetate, carrying out a constant temperature reaction, cooling to room temperature to obtain a reaction product, purifying, and carrying out vacuum drying to obtain starch acetoacetate;

(3) and (3) adding the starch acetoacetate in the step (2) into an extruder, uniformly mixing, melting, blending, extruding, injecting into a mold, and cooling to room temperature to obtain the starch-based plastic tableware.

Further, the temperature of the vacuum drying in the step (1) is 60-80 ℃, and the time of the vacuum drying is 12-24 h.

Further, the starch in the step (1) is one of corn starch, glutinous rice starch, cassava starch, potato starch, rice starch, wheat starch, barley starch, acorn starch, sago starch, sweet potato starch, high amylose starch and pea starch; the solvent is more than one of dimethyl sulfoxide (DMSO), N-dimethylacetamide (DMAc)/lithium chloride system, N-Dimethylformamide (DMF), pyridine, carbon tetrachloride, 1-ethyl-3-methylimidazole chloride salt, 1-ethyl-3-methylimidazole acetate, 1-allyl-3-methylimidazole chloride salt, 1-butyl-3-methylimidazole chloride salt and 1-butyl-3-methylimidazole dicyandiamide bromide salt.

Further, the heating and dissolving temperature in the step (1) is 80-90 ℃, and the heating and dissolving time is 0.5-2 h.

Further, the mass-to-volume ratio of the starch to the solvent in the step (1) is 20: 80g/mL-20:200 g/mL.

Preferably, the mass-to-volume ratio of the starch to the solvent in the step (1) is 20:100 g/mL.

Further, the temperature of the isothermal reaction in the step (2) is 100-120 ℃, and the time of the isothermal reaction is 1-8 h.

Preferably, the temperature of the isothermal reaction of step (2) is 110 ℃.

Further, the purification of step (2) comprises: and adding the reaction product into an ethanol solvent to separate out a white or light yellow precipitate, then fully washing the precipitate by using the ethanol solvent, and carrying out suction filtration to obtain filter residue to obtain a purified reaction product.

Preferably, the number of washing is 3.

Further, the temperature of the vacuum drying in the step (2) is 60-80 ℃, and the time of the vacuum drying is 12-24 h.

Preferably, the vacuum drying time in the step (2) is 12 h.

Preferably, the molar ratio of the tert-butyl acetoacetate in the step (2) to the starch in the step (1) is 2:1-8: 1. The degree of substitution of the acetoacetic acid starch ester in the step (2) is 0.65-2.50.

Further, the temperature of the melt blending in the step (3) is 120-180 ℃, and the time of the melt blending is 5-20 min.

The invention provides starch-based plastic tableware prepared by the preparation method.

The preparation method provided by the invention is a method for preparing modified starch based on an ester exchange method and then preparing starch-based plastic tableware by adopting a melt blending extrusion molding method. In the method, starch and acetyl tert-butyl acetate are subjected to ester exchange reaction in a solvent to prepare acetoacetic acid starch ester; then the obtained starch acetoacetate ester is melted, blended and extruded to form the starch-based plastic tableware. The starch-based plastic tableware has good biodegradability while having water resistance and heat resistance.

Reaction equation for the preparation of esterified starch:

the invention can improve the water resistance and endow the starch with plasticity of high-temperature melting property by carrying out esterification modification on starch by using the original starch, and then the disposable starch-based plastic tableware can be prepared by carrying out melt blending, extrusion and hot-press molding on the esterified modified starch.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) in the preparation method of the starch-based plastic tableware, the dissolving of the starch in the solvent and the reaction process of the starch and the esterification reagent are simple, the catalyst is not needed, the conditions are controllable, the solvent is easy to recycle, the starch and the tert-butyl acetoacetate can directly perform ester exchange reaction in the solvent to prepare the esterified starch, and the substitution degree of the product, namely the starch acetoacetate ester, can be adjusted by the molar ratio of the starch to the tert-butyl acetoacetate;

(2) in the preparation method of the starch-based plastic tableware, the starch acetoacetate is directly heated, melted and blended in an extruder, then extruded into a lunch box die, and cooled to room temperature to obtain the starch-based plastic tableware; meanwhile, the starch plastic tableware prepared by the method has good waterproofness, heat resistance and biodegradability, and meanwhile, the method can be used for preparing starch-based plastic films with different shapes and sizes, and has potential application values in the fields of food packaging, shopping bags, mulching films and the like;

(3) in the preparation method of the starch-based plastic tableware provided by the invention, the raw material starch is used as a natural polymer in nature, the raw material is rich, the price is low, and the starch-based plastic tableware is easy to biodegrade, and meanwhile, the method for preparing the starch-based plastic tableware based on the esterified starch is suitable for similar modification of most starch and derivatives thereof, provides a new method for preparing environment-friendly starch-based plastic tableware, and meets the requirements of ecological environment protection under the condition that the environmental problem is increasingly emphasized.

Drawings

FIG. 1 is an infrared spectrum of native starch and starch acetoacetate of example 1;

FIG. 2 is a nuclear magnetic hydrogen spectrum of starch acetoacetate of example 1;

FIG. 3 is a nuclear magnetic hydrogen spectrum of starch acetoacetate of example 2;

FIG. 4 is a nuclear magnetic hydrogen spectrum of starch acetoacetate of example 3.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available by commercial purchase.

The heat resistance of the starch-based plastic tableware prepared in the following examples was measured by measuring the glass transition temperature of the material, and the mechanical properties were evaluated by measuring the breaking strength of the starch-based plastic material.