阅读说明：本技术 一种抗菌包装袋用薄膜及其制备方法 (Film for antibacterial packaging bag and preparation method thereof ) 是由 周育良 周文彬 于 2020-04-30 设计创作，主要内容包括：本发明涉及包装袋领域,更具体地说,它涉及一种抗菌包装袋用薄膜及其制备方法。本发明的一种抗菌包装袋用薄膜由以下质量份的各组分混合制备而得：低密度聚乙烯10-15份；高密度聚乙烯35-45份；马来酸酐接枝聚乙烯5-10份；热塑性聚氨酯弹性橡胶10-18份；填料3-6份；纳米氧化锌-壳聚糖复合抗菌剂8-12份。本发明的一种抗菌包装袋用薄膜制备方法,包括纳米氧化锌-壳聚糖复合抗菌剂制备、薄膜挤出、薄膜流延以及薄膜裁切等步骤,本发明生产成本较低,抗菌效果好,且无毒便捷,能够用于制作食品包装袋。(The invention relates to the field of packaging bags, in particular to an antibacterial film for packaging bags and a preparation method thereof. The film for the antibacterial packaging bag is prepared by mixing the following components in parts by mass: 10-15 parts of low-density polyethylene; 35-45 parts of high-density polyethylene; 5-10 parts of maleic anhydride grafted polyethylene; 10-18 parts of thermoplastic polyurethane elastic rubber; 3-6 parts of a filler; 8-12 parts of a nano zinc oxide-chitosan composite antibacterial agent. The preparation method of the film for the antibacterial packaging bag comprises the steps of preparation of the nano zinc oxide-chitosan composite antibacterial agent, film extrusion, film casting, film cutting and the like.)

1. The film for the antibacterial packaging bag is characterized by being prepared by mixing the following components in parts by mass:

10-15 parts of low-density polyethylene;

35-45 parts of high-density polyethylene;

5-10 parts of maleic anhydride grafted polyethylene;

10-18 parts of thermoplastic polyurethane elastic rubber;

3-6 parts of a filler;

8-12 parts of a nano zinc oxide-chitosan composite antibacterial agent.

2. The film for antibacterial packing bags according to claim 1, wherein: the filler is a blend obtained by mixing zinc stearate and calcium carbonate according to the mass ratio of 1: 1.

3. The film for antibacterial packing bags according to claim 1, wherein: the particle size of the zinc stearate is 40-45 mu m, and the calcium carbonate is calcium carbonate with the particle size of more than 2000 meshes.

4. A preparation method of a film for an antibacterial packaging bag is characterized by comprising the following steps:

dissolving a chitosan raw material in a styrene-acrylate aqueous solution with the solid content of 2%, adding a sodium hydroxide solution into a water bath pot, adjusting the pH value to be alkaline to obtain a blended solution, wherein the mass of the chitosan raw material accounts for 1% of the total mass of the blended solution, adding the blended solution into the water bath pot, heating in a water bath, carrying out ultrasonic stirring for 12 hours, continuing heating in the water bath pot until the blended solution is volatilized to the residue of 1/3-1/2 after the ultrasonic stirring is finished, mixing the remaining blended solution with absolute ethyl alcohol according to the volume ratio of 1:1, standing for 3 hours, and carrying out vacuum freeze drying to obtain water-soluble modified chitosan;

dissolving water-soluble modified chitosan in water to prepare a 2-3% chitosan aqueous solution, mixing the chitosan aqueous solution and the nano zinc oxide according to the mass ratio of 100 (5-10), stirring and mixing uniformly, and performing spray drying to obtain the nano zinc oxide-chitosan composite antibacterial agent;

and step three, putting the low-density polyethylene, the high-density polyethylene, the maleic anhydride grafted polyethylene, the thermoplastic polyurethane elastic rubber, the filler and the nano zinc oxide-chitosan composite antibacterial agent into a feeding section of a casting machine together, and performing melt extrusion, casting molding and cutting processing on the materials to obtain the film for the antibacterial packaging bag.

5. The method for preparing a film for an antibacterial packing bag according to claim 4, wherein the method comprises the following steps: in the first step, the deacetylation degree of the chitosan raw material is 90-95%, and the molecular weight is 500-1000 kDa.

6. The method for preparing a film for an antibacterial packing bag according to claim 4, wherein the method comprises the following steps: in the first step, the temperature of water bath heating is 40-55 ℃.

7. The method for preparing a film for an antibacterial packing bag according to claim 4, wherein the method comprises the following steps: in the first step, 1M sodium hydroxide solution is added into a water bath to adjust the pH to be alkaline.

8. The method for preparing a film for an antibacterial packing bag according to claim 4, wherein the method comprises the following steps: in the second step, the chitosan water solution and the nano zinc oxide are mixed according to the mass ratio of 100 to 5-10, and then are stirred for 1h at the rotating speed of 600-800r/min to achieve uniform mixing.

9. The method for preparing a film for an antibacterial packing bag according to claim 4, wherein the method comprises the following steps: in the third step, the temperature of the melt extrusion section is 180-220 ℃.

Technical Field

The invention relates to the field of packaging bags, in particular to an antibacterial film for packaging bags and a preparation method thereof.

Background

The packaging bag is an industrial product widely applied to daily life of people, and more types of packaging bags need to have an antibacterial function so as to meet the packaging requirements of food, medicinal materials and other articles.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the film for the antibacterial packaging bag, which is low in production cost, non-toxic, convenient and fast and can be used for manufacturing the food packaging bag.

The invention aims to realize the technical scheme that the film for the antibacterial packaging bag is prepared by mixing the following components in parts by mass:

10-15 parts of low-density polyethylene;

35-45 parts of high-density polyethylene;

5-10 parts of maleic anhydride grafted polyethylene;

10-18 parts of thermoplastic polyurethane elastic rubber;

3-6 parts of a filler;

8-12 parts of a nano zinc oxide-chitosan composite antibacterial agent.

By adopting the technical scheme, the low-density polyethylene, the high-density polyethylene, the maleic anhydride grafted polyethylene and the thermoplastic polyurethane elastic rubber are adopted as main materials and are blended to form the film, the low-density polyethylene has good flexibility, extensibility, electric insulativity, transparency, processability and certain air permeability, the hardness, the tensile strength and the creep property of the high-density polyethylene are superior to those of the low-density polyethylene, the environmental stress cracking resistance is inferior to that of the low-density polyethylene, and the combination of the low-density polyethylene, the maleic anhydride grafted polyethylene and the thermoplastic polyurethane elastic rubber can obtain better comprehensive performance. The maleic anhydride grafted polyethylene is a polyethylene molecular chain grafted with a plurality of maleic anhydride molecules, can enhance the eutectic property between film main body materials, and particularly enables thermoplastic polyurethane elastic rubber to be blended with a plurality of polyethylenes. The main function of the filler is to save the use amount of main materials and reduce the production cost of the film. Thermoplastic polyurethane elastomer is not commonly used in packaging film per se, and zinc oxide, chitosan and other fillers reduce the elongation at break and tensile strength of the base material in conventional recognition, but the applicant researches and finds that the addition of thermoplastic polyurethane elastomer to the film can reduce the reduction range of the elongation at break and tensile strength of the film by adding the filler and the nano zinc oxide-chitosan composite antibacterial agent, and can improve the modulus of the film. Chitosan can be attached to the surface of microorganisms to prevent the growth of the microorganisms, zinc oxide can change oxygen in air and water into active oxygen under illumination on the one hand, the active oxygen can destroy the biological structure of microorganism cells, zinc ions can destroy the membrane protein structure of the microorganism cells on the other hand, the zinc oxide and the chitosan are compounded, a structure of chitosan-coated nano zinc oxide can be formed, the antibacterial effect is synergistically enhanced, the zinc oxide and the chitosan are safe additives, and excessive pathogenic risks do not exist.

Preferably, the filler is a blend of zinc stearate and calcium carbonate mixed according to a mass ratio of 1: 1.

By adopting the technical scheme, the production cost of the film can be reduced by adding calcium carbonate as a filler, the using amount of the main material is saved, and the casting performance of the main material can be improved by adding zinc stearate.

Preferably, the particle size of the zinc stearate is 40-45 μm, and the calcium carbonate is calcium carbonate with a particle size of more than 2000 meshes.

By adopting the technical scheme, the zinc stearate has the particle size of 40-45 mu m, and the calcium carbonate has the particle size of more than 2000 meshes, so that the film is smoother.

The second purpose of the invention is to provide a preparation method of the film for the antibacterial packaging bag, and the prepared film for the antibacterial packaging bag has good antibacterial effect, is safe and nontoxic and can be used for manufacturing food packaging bags.

The technical purpose of the invention is realized by the following technical means, and the preparation method of the film for the antibacterial packaging bag comprises the following steps:

dissolving a chitosan raw material in a styrene-acrylate aqueous solution with the solid content of 2%, adding a sodium hydroxide solution into a water bath pot, adjusting the pH value to be alkaline to obtain a blended solution, wherein the mass of the chitosan raw material accounts for 1% of the total mass of the blended solution, adding a co-mixed solution into the water bath pot, heating in a water bath, carrying out ultrasonic stirring for 12 hours, continuing heating in the water bath after the ultrasonic stirring is finished until the blended solution in the water bath pot volatilizes to the residue of 1/3-1/2, mixing the remaining blended solution with absolute ethyl alcohol according to the volume ratio of 1:1, standing for 3 hours, and carrying out vacuum freeze drying to obtain water-soluble modified chitosan;

dissolving water-soluble modified chitosan in water to prepare a 2-3% chitosan aqueous solution, mixing the chitosan aqueous solution and the nano zinc oxide according to the mass ratio of 100 (5-10), stirring and mixing uniformly, and performing spray drying to obtain the nano zinc oxide-chitosan composite antibacterial agent;

and step three, putting the low-density polyethylene, the high-density polyethylene, the maleic anhydride grafted polyethylene, the thermoplastic polyurethane elastic rubber, the filler and the nano zinc oxide-chitosan composite antibacterial agent into a feeding section of a casting machine together, and performing melt extrusion, casting molding and cutting processing on the materials to obtain the film for the antibacterial packaging bag.

By adopting the technical scheme, in the first step, under the condition of alkaline environment and ultrasonic stirring, amino groups in the chitosan raw material can react with a styrene acrylate aqueous solution, so that chitosan macromolecules are provided with a group with good water solubility. And (3) volatilizing the blending solution in the water bath until only 1/3-1/2 is left by heating in a water bath, adding absolute ethyl alcohol into the blending solution, and standing, mainly for better separating out water-soluble modified chitosan and saving energy consumed during vacuum freeze drying. In the second step, the nano zinc oxide cannot be dissolved in the aqueous solution, the water-soluble modified chitosan can be adsorbed around the zinc oxide in the stirring and mixing process, and finally a uniform emulsion is obtained, and the powder obtained by spray drying is the nano zinc oxide-chitosan composite antibacterial agent. The third step is a general cast film processing process, and as the invention has reasonable proportion and good selection and compatibility of all components, the nano zinc oxide-chitosan composite antibacterial agent and the main material of the film are molded together, compared with the mode of coating the nano zinc oxide-chitosan composite antibacterial agent on the plastic film, the mode has more lasting antibacterial effect.

Preferably, in the step one, the deacetylation degree of the chitosan raw material is 90-95%, and the molecular weight is 500-1000 kDa.

By adopting the technical scheme, the chitosan with high deacetylation degree has good antibacterial effect, and the chitosan with the molecular weight of 500-plus-1000 kDa is easy to adhere around the zinc oxide to form a composite antibacterial material with the zinc oxide.

Preferably, in step one, the temperature of the water bath heating is 40-55 ℃.

Preferably, in the first step, 1M sodium hydroxide solution is added into a water bath to adjust the pH to be alkaline.

By adopting the technical scheme, the 1M sodium hydroxide solution has stronger alkalinity, and the whole environment in the water bath kettle can be adjusted to be alkaline only by dropwise adding a small amount of 1M sodium hydroxide solution.

Preferably, in the second step, the chitosan aqueous solution and the nano zinc oxide are mixed according to the mass ratio of 100 to (5-10), and then stirred for 1 hour at the rotating speed of 600-800r/min to achieve uniform mixing.

By adopting the technical scheme, the chitosan aqueous solution and the nano zinc oxide can be fully and uniformly mixed by stirring for 1h at the rotating speed of 600-800 r/min.

Preferably, in the third step, the temperature of the melt extrusion section is 180-220 ℃.

By adopting the technical scheme, the chitosan in the zinc oxide-chitosan composite antibacterial agent is not decomposed at the same temperature, and the base materials of the film can be fully melted and mixed.

In summary, the invention includes at least one of the following beneficial technical effects:

firstly, the production cost is low;

secondly, the food packaging bag is nontoxic and convenient, and can be used for manufacturing food packaging bags;

thirdly, the antibacterial effect is good.

Detailed Description

The present invention will be described in detail with reference to examples.