阅读说明：本技术 一种可降解的聚乳酸树脂保鲜膜及其制备方法 (Degradable polylactic resin preservative film and preparation method thereof ) 是由 杨勇 于 2020-11-17 设计创作，主要内容包括：本发明涉及聚乳酸保鲜膜技术领域,具体地说,涉及一种可降解的聚乳酸树脂保鲜膜及其制备方法。其包括以下原料组成：聚乳酸树脂、可降解材料、增塑剂、接枝剂、纤维素、抗菌剂,本发明制备的可降解的聚乳酸树脂保鲜膜,通过加入的可降解材料,不仅可以提高改性后复合材料的机械韧性,还能使改性后的复合材料生物降解性能得到提高,使其拉伸性能、断裂伸长率、生物相容性和抗冲击强度都有一定程度的增加,加入的增塑剂和接枝剂与聚乳酸进行共混,使改性后复合材料的弹性、透明度、拉伸强度以及断裂伸长率均有大部分提高,通过加入的天然抗菌剂,使聚乳酸抗菌性能得到提高,抑菌持效时间长,使保鲜膜的同时具有卫生性和保健性。(The invention relates to the technical field of polylactic acid preservative films, in particular to a degradable polylactic acid resin preservative film and a preparation method thereof. The feed comprises the following raw materials: the degradable polylactic resin preservative film prepared by the invention can improve the mechanical toughness of the modified composite material and can also improve the biodegradability of the modified composite material to a certain extent by adding the degradable material, the added plasticizer and the grafting agent are blended with polylactic acid to improve most of the elasticity, transparency, tensile strength and elongation at break of the modified composite material, and the added natural antibacterial agent is used for improving the antibacterial property of the polylactic acid, so that the preservative film has the advantages of long bacteriostatic duration and sanitation and health care.)

1. A degradable polylactic resin preservative film comprises the following raw materials: 70-90 parts of polylactic resin, 5-20 parts of degradable material, 10-25 parts of plasticizer, 2-10 parts of grafting agent, 10-30 parts of cellulose and 8-15 parts of antibacterial agent.

2. The degradable polylactic resin preservative film according to claim 1, wherein: the degradable material is selected from at least one of polyethylene lactone and poly butylene succinate.

3. The degradable polylactic resin preservative film according to claim 1, wherein: the plasticizer is selected from at least one of polyethylene glycol, acetyl tri-n-butyl citrate and isosorbide.

4. The degradable polylactic resin preservative film according to claim 1, wherein: the grafting agent is selected from at least one of maleic anhydride and glycidyl methacrylate.

5. The degradable polylactic resin preservative film according to claim 1, wherein: the cellulose is at least one selected from lignocellulose, fruit cellulose and hemp cellulose.

6. The degradable polylactic resin preservative film according to claim 1, wherein: the antibacterial agent is a natural antibacterial agent, and the natural antibacterial agent is at least one selected from conifer essence, folium Artemisiae Argyi essence, Glycyrrhrizae radix essence, herba Houttuyniae essence, and folium Camelliae sinensis essence.

7. A degradable polylactic resin preservative film, comprising the degradable polylactic resin preservative film according to any one of claims 1 to 6, and the operation steps are as follows:

s1, adding the polylactic resin, the degradable material and the grafting agent into a stirring kettle, and uniformly mixing;

s2, adding the plasticizer into the stirring kettle, stirring for 1-2h, and uniformly mixing;

s3, adding cellulose and an antibacterial agent, reducing the temperature, and stirring for 1-2h to obtain a mixture;

s4, adding the mixture into a double-screw extruder, blending and extruding;

and S5, adding the extrudate into a blow molding extruder for extrusion to obtain the polylactic resin preservative film.

8. The method for preparing the degradable polylactic resin preservative film according to claim 7, which is characterized in that: in the S1-S2, the temperature of the stirring kettle is 100-120 ℃, and the stirring speed is 90-100 r/min.

9. The method for preparing the degradable polylactic resin preservative film according to claim 7, which is characterized in that: in the S4, the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

10. The method for preparing the degradable polylactic resin preservative film according to claim 7, which is characterized in that: in the S5, the extrusion temperature of the blow molding extruder is 170-210 ℃.

Technical Field

The invention relates to the technical field of polylactic acid preservative films, in particular to a degradable polylactic acid resin preservative film and a preparation method thereof.

Background

Polylactic acid (PLA) is a novel biodegradable material, is prepared from starch raw materials provided by renewable plant resources (such as corn), is saccharified to obtain glucose, is fermented by the glucose and certain strains to prepare high-purity lactic acid, and is synthesized into polylactic acid with a certain molecular weight by a chemical synthesis method. The common plastic treatment method still burns to cause a large amount of greenhouse gases to be discharged into the air, the polylactic acid plastic is buried in the soil to be degraded, the generated carbon dioxide directly enters soil organic matters or is absorbed by plants, the carbon dioxide cannot be discharged into the air, the greenhouse effect cannot be caused, the preservative film prepared from the polylactic acid resin has good air permeability, oxygen permeability and carbon dioxide permeability and also has the characteristic of odor isolation, the existing polylactic acid resin preservative film has the defects of poor antibacterial performance, long degradation time and poor mechanical property, and therefore, a novel polylactic acid preservative film is needed to make up the defects in the aspects.

Disclosure of Invention

The invention aims to provide a degradable polylactic resin preservative film and a preparation method thereof, which aim to solve the problems in the background technology.

In order to achieve the above objects, in one aspect, the present invention provides a degradable polylactic resin preservative film and a preparation method thereof, wherein the degradable polylactic resin preservative film comprises the following raw materials: 70-90 parts of polylactic resin, 5-20 parts of degradable material, 10-25 parts of plasticizer, 2-10 parts of grafting agent, 10-30 parts of cellulose and 8-15 parts of antibacterial agent.

As a further improvement of the technical scheme, the degradable material is selected from at least one of polyethylene lactone and polybutylene succinate, PLA and polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are improved to a certain extent by blending PLA and polybutylene succinate.

As a further improvement of the technical scheme, the plasticizer is selected from at least one of polyethylene glycol, acetyl tributyl citrate and isosorbide, and one of the plasticizers is added for blending, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are all improved for the most part.

As a further improvement of the technical scheme, the grafting agent is selected from at least one of maleic anhydride and glycidyl methacrylate, and the mechanical property of PLA modified by the grafting agent is obviously improved.

As a further improvement of the technical scheme, the cellulose is selected from at least one of lignocellulose, fruit cellulose and hemp cellulose, and the PLA modified by using the cellulose has the advantages of obviously improved thermal stability and mechanical property, and improved shortcomings of high cost and poor flame retardance of the PLA.

As a further improvement of the technical scheme, the antibacterial agent is a natural antibacterial agent, and the natural antibacterial agent is selected from at least one of conifer essence, artemisia argyi essence, liquorice essence, houttuynia cordata essence and tea essence, and has the antibacterial and antivirus effects.

On the other hand, the invention provides a preparation method of a degradable polylactic resin preservative film, which comprises the following operation steps:

s1, adding the polylactic resin, the degradable material and the grafting agent into a stirring kettle, and uniformly mixing;

s2, adding the plasticizer into the stirring kettle, stirring for 1-2h, and uniformly mixing;

s3, adding cellulose and an antibacterial agent, reducing the temperature, and stirring for 1-2h to obtain a mixture;

s4, adding the mixture into a double-screw extruder, blending and extruding;

and S5, adding the extrudate into a blow molding extruder for extrusion to obtain the polylactic resin preservative film.

Preferably, in S1-S2, the temperature of the stirring kettle is 100-120 ℃, and the stirring speed is 90-100 r/min.

Preferably, in the S4, the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Preferably, in the S5, the extrusion temperature of the blow molding extruder is 170-210 ℃.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the degradable polylactic resin preservative film and the preparation method thereof, the degradable material is added, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are improved to a certain extent.

2. In the degradable polylactic resin preservative film and the preparation method thereof, the added plasticizer is blended with polylactic acid, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are improved for the most part.

3. In the degradable polylactic resin preservative film and the preparation method thereof, the added grafting agent is blended with polylactic acid, and the mechanical property of PLA modified by the grafting agent is obviously improved.

4. According to the degradable polylactic resin preservative film and the preparation method thereof, the natural antibacterial agent is added, so that the antibacterial performance of polylactic acid is improved, the antibacterial lasting time is long, and the preservative film has sanitation and health care.

Drawings

FIG. 1 is an overall flow diagram of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Embodiment 1 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 70 parts of polylactic resin, 5 parts of degradable material and 2 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the polylactic resin, the degradable material and the grafting agent are uniformly mixed; adding 10 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 10 parts of cellulose and 8 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polyethylene lactone and polybutylene succinate, PLA and the polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can also be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are increased to a certain extent by blending the PLA and the polybutylene succinate;

the plasticizer is selected from polyethylene glycol, acetyl tributyl citrate and isosorbide, and is added and blended, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are improved for the most part;

the antibacterial agent is a natural antibacterial agent selected from conifer essence, folium artemisiae argyi essence, liquorice essence, houttuynia cordata essence and tea essence, and has the antibacterial and antivirus effects.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 2 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polyethylene lactone and polybutylene succinate, PLA and the polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can also be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are increased to a certain extent by blending the PLA and the polybutylene succinate;

the plasticizer is selected from polyethylene glycol, acetyl tributyl citrate and isosorbide, and is added and blended, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are improved for the most part;

the antibacterial agent is a natural antibacterial agent selected from conifer essence, folium artemisiae argyi essence, liquorice essence, houttuynia cordata essence and tea essence, and has the antibacterial and antivirus effects.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 3 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 90 parts of polylactic resin, 20 parts of degradable material and 10 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the polylactic resin, the degradable material and the grafting agent are uniformly mixed; adding 25 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 30 parts of cellulose and 15 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polyethylene lactone and polybutylene succinate, PLA and the polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can also be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are increased to a certain extent by blending the PLA and the polybutylene succinate;

the plasticizer is selected from polyethylene glycol, acetyl tributyl citrate and isosorbide, and is added and blended, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are improved for the most part;

the antibacterial agent is a natural antibacterial agent selected from conifer essence, folium artemisiae argyi essence, liquorice essence, houttuynia cordata essence and tea essence, and has the antibacterial and antivirus effects.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 4 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polyethylene lactone, and PLA and the polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, and the biodegradability of the modified composite material can be improved;

the plasticizer is selected from polyethylene glycol, the added polyethylene glycol is blended and injected to form a sample, the blended polylactic resin has better elasticity and high transparency, the elongation at break can reach 412%, and when the content of the polyethylene glycol is lower than 8%, the tensile strength and the elongation at break of the polylactic resin can be improved along with the continuous increase of the polyethylene glycol;

the antibacterial agent is selected from conifer essence, the antibacterial mechanism of conifer oil is that 2 oxygen atoms for coordination and complexation are arranged on the molecular structure, the conifer oil is denatured by the action of the oxygen atoms and proteins in microorganisms, the antibacterial effect is wide, and the conifer oil has a strong killing effect on fungi.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 5 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polybutylene succinate, PLA and the polybutylene succinate are mixed and modified, the melting point and the crystallization point of the modified product are relatively reduced, but the tensile strength, the elongation at break, the biocompatibility and the impact strength are increased to a certain extent;

the plasticizer is selected from acetyl tri-n-butyl citrate, the acetyl tri-n-butyl citrate is blended with polylactic acid, and the elongation at break of the modified composite material is gradually improved along with the increase of the content of the acetyl tri-n-butyl citrate;

the antibacterial agent is selected from folium Artemisiae Argyi essence, and the main ingredients of folium Artemisiae Argyi include 1, 8-aminophylline, A-ketone, acetylcholine, choline, etc., which have antibacterial, antiinflammatory, antiallergic and blood circulation promoting effects.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 6 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polybutylene succinate, PLA and the polybutylene succinate are mixed and modified, the melting point and the crystallization point of the modified product are relatively reduced, but the tensile strength, the elongation at break, the biocompatibility and the impact strength are increased to a certain extent;

the plasticizer is selected from isosorbide, the isosorbide and the polylactic acid are blended, the isosorbide can effectively reduce the glass transition temperature of the polylactic acid, and the breaking elongation of the polylactic acid can be obviously improved;

the antibacterial agent is selected from Glycyrrhrizae radix essence, Glycyrrhrizae radix contains glycyrrhizin with sweet taste 150 times of sucrose, and has effects of resisting inflammation, resisting allergy, resisting ulcer and removing toxic substance, and is safe to human body.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 7 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polybutylene succinate, PLA and the polybutylene succinate are mixed and modified, the melting point and the crystallization point of the modified product are relatively reduced, but the tensile strength, the elongation at break, the biocompatibility and the impact strength are increased to a certain extent;

the plasticizer is selected from polyethylene glycol, the added polyethylene glycol is blended and injected to form a sample, the blended polylactic resin has better elasticity and high transparency, the elongation at break can reach 412%, and when the content of the polyethylene glycol is lower than 8%, the tensile strength and the elongation at break of the polylactic resin can be improved along with the continuous increase of the polyethylene glycol;

the antibacterial agent is selected from herba Houttuyniae essence, the herba Houttuyniae is perennial herb of Boraginaceae, and the medicinal components of leaf and stem of herba Houttuyniae mainly contain decanoyl acetaldehyde and methyl nonyl ketone lauric acid, and has strong antibacterial effect on staphylococci and filamentous bacteria.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Embodiment 8 a degradable polylactic resin preservative film and a preparation method thereof, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polybutylene succinate, PLA and the polybutylene succinate are mixed and modified, the melting point and the crystallization point of the modified product are relatively reduced, but the tensile strength, the elongation at break, the biocompatibility and the impact strength are increased to a certain extent;

the plasticizer is selected from polyethylene glycol, the added polyethylene glycol is blended and injected to form a sample, the blended polylactic resin has better elasticity and high transparency, the elongation at break can reach 412%, and when the content of the polyethylene glycol is lower than 8%, the tensile strength and the elongation at break of the polylactic resin can be improved along with the continuous increase of the polyethylene glycol;

the antibacterial agent is selected from tea essence, the tea contains various chemical components, mainly comprises polyphenol compounds, alkaloid (caffeine), catechin and the like, and researches show that the catechin has an inhibiting effect on microorganisms such as streptococcus, staphylococcus aureus and the like, can inhibit the activity of tyrosine decarboxylase, and has a plurality of medicinal functions such as antivirus, antifungal, detoxification and anticancer and the like.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

In the above examples 1-8:

the grafting agent is selected from at least one of maleic anhydride and glycidyl methacrylate, and the mechanical property of PLA modified by the grafting agent is obviously improved;

the cellulose is selected from at least one of lignocellulose, fruit cellulose and hemp cellulose, and the PLA modified by the cellulose has obviously improved thermal stability and mechanical property, and simultaneously overcomes the defects of high cost and poor flame retardance of the PLA.

The degradable polylactic resin preservative film prepared by the invention has good antibacterial property, the impact strength and the elongation are greatly improved, and the detection indexes of the degradable polylactic resin preservative film prepared by the invention are shown in table 1:

TABLE 1

According to table 1, in examples 1-3, when the added antibacterial agent is 11.5 minutes, the antibacterial rate of the polylactic resin preservative film for various germs is over 95%, the antibacterial rate of staphylococcus is 99.5%, and when the dosage of the antibacterial agent is reduced, the antibacterial rate of each item is the lowest;

in examples 1-3, when 80 parts of polylactic acid resin, 12.5 parts of degradable material, 6 parts of grafting agent, 17.5 parts of plasticizer and 20 parts of cellulose are added, the tensile strength and elongation at break of the polylactic acid resin are both greatly improved;

in examples 4 to 8, it can be seen that when the degradable material is polybutylene succinate and the plasticizer is polyethylene glycol, the tensile strength and elongation at break of the polylactic acid are in the highest state;

in examples 4 to 8, it can be seen that when the antibacterial agent is tea essence, the polylactic acid resin has a higher bacteriostatic ratio against escherichia coli, staphylococcus and candida albicans than other natural antibacterial agents.

Comparative example 1 a degradable polylactic resin cling film and method for preparing the same, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polyethylene lactone and polybutylene succinate, PLA and the polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can also be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are increased to a certain extent by blending the PLA and the polybutylene succinate;

the antibacterial agent is a natural antibacterial agent selected from conifer essence, folium artemisiae argyi essence, liquorice essence, houttuynia cordata essence and tea essence, and has the antibacterial and antivirus effects.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Comparative example 2 a degradable polylactic resin cling film and method for preparing the same, comprising:

first, blending process

Adding 80 parts of polylactic resin, 12.5 parts of degradable material and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the components are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the degradable material is selected from polyethylene lactone and polybutylene succinate, PLA and the polyethylene lactone are mixed and modified, so that the mechanical toughness of the modified composite material can be improved, the biodegradability of the modified composite material can also be improved, and the tensile property, the elongation at break, the biocompatibility and the impact strength of the modified composite material are increased to a certain extent by blending the PLA and the polybutylene succinate;

the plasticizer is selected from polyethylene glycol, acetyl tributyl citrate and isosorbide, and the plasticizer is added for blending, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are improved for the most part.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

Comparative example 3 a degradable polylactic resin cling film and method for preparing the same, comprising:

first, blending process

Adding 80 parts of polylactic resin and 6 parts of grafting agent into a stirring kettle, wherein the temperature of the stirring kettle is 100-120 ℃, the stirring speed is 90-100r/min, and the polylactic resin and the grafting agent are uniformly mixed; adding 17.5 parts of plasticizer into a stirring kettle, stirring for 1-2 hours, and uniformly mixing; adding 20 parts of cellulose and 11.5 parts of antibacterial agent, reducing the temperature, and stirring for 1-2 hours to prepare a mixture;

the plasticizer is selected from polyethylene glycol, acetyl tributyl citrate and isosorbide, and is added and blended, so that the elasticity, the transparency, the tensile strength and the elongation at break of the modified composite material are improved for the most part;

the antibacterial agent is a natural antibacterial agent selected from conifer essence, folium artemisiae argyi essence, liquorice essence, houttuynia cordata essence and tea essence, and has the antibacterial and antivirus effects.

Second, extrusion Process

Adding the mixture into a double-screw extruder for blending and extrusion, wherein the extrusion temperature of the double-screw extruder is 165-200 ℃, and the screw rotating speed is 30-50 rpm.

Blow molding

And adding the extrudate into a blow molding extruder for extrusion, wherein the extrusion temperature of the blow molding extruder is 170-210 ℃, and the polylactic resin preservative film is prepared.

In the preparation process of the degradable polylactic resin preservative film, the preservative film has high antibacterial property and good mechanical property, and has a great relationship with an antibacterial agent and a plasticizer added into the preservative film, and in order to verify the related technical scheme, the applicant performs the following tests:

comparative examples 1 to 2: by adopting the method of example 2, the related indexes of the prepared degradable polylactic resin preservative film are detected under the conditions of antibacterial agent removal and plasticizer removal, and the specific indexes are shown in table 2:

TABLE 2

As shown in table 2, in the case of removing the antibacterial agent and the plasticizer, the antibacterial property and the mechanical property of the polylactic acid resin are both greatly reduced in comparative example 2, and thus it can be seen that the antibacterial agent and the plasticizer are important factors affecting the antibacterial property and the mechanical property of the preservative film made of polylactic acid resin.

Test example 1

In the degradation test of the polylactic acid resin preservative film bases provided in the above examples 1 to 8 and comparative examples 1 to 3, each preservative film was weighed by the soil burying method, buried in the early land below with a depth of 30cm after the uniform mass, and uniformly taken out after 60 days to check the degradation degree, which is specifically shown in table 3:

TABLE 3

As shown in Table 3, in 60 days, when 12.5 parts of degradable material is added, the degradation rate of the polylactic acid preservative film is the highest, the degradation effect is the best, and when the degradable material is removed, the degradation effect of the polylactic acid preservative film is the worst, so that the degradable material is an important factor influencing the degradation speed of the polylactic acid resin preservative film.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.