CN116904009A

CN116904009A - Biodegradable preservative film and preparation method thereof

Info

Publication number: CN116904009A
Application number: CN202311048106.4A
Authority: CN
Inventors: 宋清魁; 赵勇; 赵鹏
Original assignee: Cangzhou Jinsanyang Plastic Industry Co ltd
Current assignee: Cangzhou Jinsanyang Plastic Industry Co ltd
Priority date: 2023-05-15
Filing date: 2023-08-21
Publication date: 2023-10-20
Also published as: CN116285277A

Abstract

The application provides a biodegradable preservative film which comprises polylactic acid, thermoplastic starch, a polylactic acid toughening agent, a nucleating agent, a lubricant, catechol, ethylcellulose and an ultraviolet resistant agent, and is characterized by further comprising poly (3-hydroxybutyrate-3-hydroxycaproic acid ester) and poly (3-hydroxybutyrate-4-hydroxybutyrate). The mass ratio of the poly (3-hydroxybutyrate-3-hydroxycaproate) to the poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3. The mass content of the poly (3-hydroxybutyrate-3-hydroxycaproate) is 2% -3% based on the total mass of the biodegradable preservative film. The biodegradable preservative film can improve the biodegradation rate, improve the degradation process and meet the environmental protection application.

Description

Biodegradable preservative film and preparation method thereof

The application claims priority of China patent application filed in 2023, 5 and 15 days with the application number of 202310540019.4 and the application name of 'a biodegradable preservative film and a preparation method thereof', which are all incorporated by reference.

Technical Field

The application belongs to the technical field of preservative films, and particularly relates to a biodegradable preservative film and a preparation method thereof.

Background

If food is directly put into the refrigerator, the refrigerator is easy to generate peculiar smell, and the taste of the refrigerator can be absorbed, especially the starch food is easy to absorb the peculiar smell in the refrigerator. In order to keep food fresh, modern people can use a preservative film to package the food and put the food into a refrigerator, so that the food is not easy to deteriorate, and the preservation time is prolonged. The preservative film is excellent in oxygen barrier property, water vapor barrier property (moisture resistance) and transparency, and can be heated by a microwave oven, and therefore, is widely used for packaging of fresh fish, raw meat, processed meat, fresh vegetables, food and the like for the purpose of oxygen resistance, moisture resistance and the like. Therefore, the preservative film is one of the kitchen supplies which are indispensable for families at present.

The traditional preservative films are cylindrical, and when the preservative films are used, a section of wrapped food needs to be pulled out and cut off by scissors. After the use is completed, the preservative film can be thrown away together with kitchen garbage and then is destroyed by being carried by environmental protection personnel, but the prior preservative film has relatively poor biodegradation and greatly pollutes the environment.

Currently, for example, the prior art publication No. CN101475735A discloses that hydroxyalkanoates (PHAs) are a class of high molecular polyesters synthesized by microorganisms, which generally have molecular weights of between tens of thousands and millions, and are widely found in various microorganisms in nature. As the polymerization monomers and the polymerization degree are different, PHAs can realize the change of elasticity from brittleness and hardness to softness, the molecular weight can be adjusted between tens of thousands and millions, the glass transition temperature can be as low as-50 ℃, the tensile elongation at break can reach more than 200 percent, the melting point can be changed within the range of 50-180 ℃, and the crystallinity can be between 10 and 80 percent. Has complete biodegradability. However, the heat shrinkage rate is poor, and the current practical requirements can not be met when the microwave oven and the like are heated for use. And the existing preservative film has poor biodegradability and low environmental friendliness.

Poly (3-hydroxybutyrate-3-hydroxycaproate) (PHBHHx) is a more common product in PHAs. PHBHHx has better elasticity and plasticity, and PHBHHx has better mechanical property than other products. PHBHHx has low crystallinity, and hardness and brittleness are improved to a certain extent. PHBHHx has excellent biodegradability, and also has good plasticity and hardness.

Poly (3-hydroxybutyrate) -4-hydroxybutyrate copolymer (P3 HB4 HB) in biodegradable plastics is a thermoplastic polyester synthesized by prokaryotes as a carbon source and energy source for storage under the condition of unbalanced nutrition of carbon and nitrogen. Is a novel completely degradable biological material, has excellent toughness and biodegradability compared with other biological plastic materials, and can be developed and produced by Shenzhen Yikeman technology Co., ltd., U.S.A.

Therefore, we propose a biodegradable preservative film and a preparation method thereof to solve the above problems.

Disclosure of Invention

The application provides a biodegradable preservative film, which can improve the biodegradation rate and the degradation process, has good heating performance and meets the environmental protection application.

The application provides a biodegradable preservative film which comprises polylactic acid, thermoplastic starch, a polylactic acid toughening agent, a nucleating agent, a lubricant, catechol, ethylcellulose and an ultraviolet resistant agent, and is characterized by further comprising poly (3-hydroxybutyrate-3-hydroxycaproic acid ester) and poly (3-hydroxybutyrate-4-hydroxybutyrate).

In some embodiments, the mass ratio of poly (3-hydroxybutyrate-3-hydroxyhexanoate) to poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2 to 3.

In some embodiments, the poly (3-hydroxybutyrate-3-hydroxyhexanoate) is present in an amount of 2% to 3% by mass based on the total mass of the biodegradable wrap.

In some embodiments, the poly (3-hydroxybutyrate-4-hydroxybutyrate) is 1% to 4% by mass based on the total mass of the biodegradable wrap.

In some embodiments, the nucleating agent comprises talc, calcium carbonate, mica or clay.

In some embodiments, the nucleating agent comprises at least two of zinc stearate, magnesium salt, calcium salt, or barium salt.

In some embodiments, the preservative film has a TD heat shrinkage of 5% or less at 130 ℃.

The lubricant is not particularly limited, and specific examples thereof include fatty acid hydrocarbon-based lubricants such as ethylene bis-stearamide, butyl stearate, polyethylene wax, paraffin wax, carnauba wax, myristyl myristate, stearyl stearate, and the like, higher fatty acid lubricants, fatty amide-based lubricants, fatty acid ester lubricants, and the like. The lubricant may be used alone or in combination of two or more.

Among these, polylactic acid PLA may also be selected from other substances, such as: one or more of polycaprolactone PCL, polybutylene succinate PBS, poly (butylene succinate)/polybutylene terephthalate) PBAT, polycarbonate PPC, polyglutamic acid PGA, polyvinyl alcohol PVA, starch and cellulose.

Among them, examples of the ultraviolet ray-resistant agent include, but are not limited to, benzotriazole-based ultraviolet ray absorbers such as 2- (2 '-hydroxy-5' -methylphenyl) benzotriazole, 2- (2 '-hydroxy-3', 5 '-tert-butylphenyl) benzotriazole, and 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -5-chlorobenzotriazole; benzophenone-based ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone, or hindered amine-based light stabilizers. The application is preferably an ultraviolet absorber UV-531.

In some embodiments, the preservative film has a thickness in the range of 13 to 15 μm. More preferably 13 to 14. Mu.m, the thickness of the preservative film may be 13 μm, 13.1. Mu.m, 13.5. Mu.m, 13.8. Mu.m, 14. Mu.m, or 14.5. Mu.m. By enabling the thickness of the preservative film to be within the range, the faults of film breaking are inhibited, the film breaking is better controlled, and the economical efficiency is greatly improved.

A preparation method of a biodegradable preservative film comprises the following steps:

raw material mixing: physically mixing polylactic acid, thermoplastic starch, a polylactic acid toughening agent, a nucleating agent, a lubricant, catechol, ethylcellulose, an ultraviolet resistant agent, poly (3-hydroxybutyrate-3-hydroxycaproic acid ester) and poly (3-hydroxybutyrate-4-hydroxybutyrate), then bracing, water-cooling and granulating;

and (3) blow molding production of preservative films: and extruding and blow molding the product prepared in the raw material mixing step by a single screw extruder to produce the degradable preservative film.

In some embodiments, TD stretching is included such that the preservative film has a TD heat shrinkage of 5% or less at 130 ℃.

In some embodiments, the stretching and relaxing steps are performed 1 time each in the TD direction of the preservative film, and the deformation speed in the stretching step is 15%/sec and the relaxing speed is 5%/sec.

The biodegradable preservative film provided by the application comprises poly (3-hydroxybutyrate-3-hydroxycaproate) and poly (3-hydroxybutyrate-4-hydroxybutyrate), wherein the mass ratio of the poly (3-hydroxybutyrate-3-hydroxycaproate) to the poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3, so that the biodegradation rate can be improved, the degradation process can be improved, and the environment-friendly application can be satisfied.

The preservative film has good heat shrinkage rate, can be better used in environments such as high temperature, and has good synergistic effect in a proper proportion range of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester) and poly (3-hydroxybutyrate-4-hydroxybutyrate), so that the preservative film is degradable and has proper heat shrinkage rate.

The thickness range of the preservative film is 13-15 mu m, and the preservative film has better heat shrinkage in the MD direction and TD direction, and can be better used in high-temperature environments and the like.

The biodegradable preservative film provided by the application has better biodegradability.

Detailed Description

The following description of the embodiments of the present application will clearly and fully describe the technical solutions of the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

The preservative film of the present embodiment includes a flow direction (hereinafter also referred to as "MD direction") and a direction perpendicular to the flow direction (hereinafter also referred to as "TD direction").

The preservative film of the present embodiment may contain additives other than the above. The additive is not particularly limited, and a plasticizer may be added to the preservative film in order to increase the performance thereof, and the plasticizer is not particularly limited, and a nonvolatile solvent capable of forming a uniform solution at a temperature not lower than the melting point of the polyolefin is preferably used. Specific examples of such a nonvolatile solvent include hydrocarbons such as liquid paraffin and paraffin wax; esters such as dioctyl phthalate and dibutyl phthalate; higher alcohols such as oleyl alcohol and stearyl alcohol. These plasticizers may be recovered by distillation or the like after extraction and reused. Further, the polyolefin resin, other additives and plasticizer are preferably kneaded in advance at a predetermined ratio using a henschel mixer or the like before being fed into the resin kneading apparatus. More preferably, in the preliminary kneading, a part of the plasticizer to be used is charged, and the remaining plasticizer is heated appropriately and fed sideways to the resin kneading apparatus to be kneaded. By using this kneading method, the dispersibility of the plasticizer improves, and when a sheet-like molded article of a melt-kneaded product of the resin composition and the plasticizer is stretched in a subsequent step, the sheet-like molded article tends to be stretched at a high rate without breaking the film.

Among the plasticizers, if the polyolefin resin is polyethylene or polypropylene, the liquid paraffin has high compatibility with the polyethylene or polypropylene, and even if the melt-kneaded product is stretched, interfacial peeling between the resin and the plasticizer is less likely to occur, and uniform stretching tends to be easily performed.

The antifogging agent may be added, and the antifogging agent is not particularly limited, and specifically includes glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene fatty acid alcohol ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and the like. The antifogging agent may be used alone or in combination of two or more.

The antibacterial agent may be added, and the antibacterial agent is not particularly limited, and specifically, silver-based inorganic antibacterial agents and the like are exemplified. The antibacterial agent may be used alone or in combination of two or more.

The application provides a biodegradable preservative film which comprises polylactic acid, thermoplastic starch, a polylactic acid toughening agent, a nucleating agent, a lubricant, catechol, ethylcellulose and an ultraviolet resistant agent, and is characterized by further comprising poly (3-hydroxybutyrate-3-hydroxycaproic acid ester) and poly (3-hydroxybutyrate-4-hydroxybutyrate). Among them, poly (3-hydroxybutyrate-3-hydroxycaproate) is also called PHBHHx, and poly (3-hydroxybutyrate-3-hydroxycaproate) in the present application is purchased from (Holly, acacia Mitsui, inc.). Poly (3-hydroxybutyrate-4-hydroxybutyrate) of the present application was purchased from Shenzhen Yikeman technologies Co.

In some embodiments, the nucleating agent comprises talc, calcium carbonate, mica or clay. In some embodiments, the nucleating agent is not particularly limited, and specifically, a metal phosphate salt and the like are exemplified. The nucleating agent may be used alone or in combination of two or more.

Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.

Thermoplastic starch of the application is purchased from YC100 of Yuchuan degradation materials limited company in Jiangyin city, polylactic acid toughening agent is purchased from DF0020 of Defu, and other ingredients: the nucleating agent, the lubricant, the catechol, the ethylcellulose, the ultraviolet resistant agent and the polylactic acid are all commercially available, and the application is not limited to the sources thereof.

Example 1:

30% of thermoplastic starch, 2% of polylactic acid toughening agent, 3% of nucleating agent, 2% of lubricant, 2% of catechol, 1% of ethylcellulose, 1% of ultraviolet resistant agent, 2% of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester), 1% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;

wherein, the nucleating agent is 1% of calcium carbonate and 2% of mica.

Example 2:

30% of thermoplastic starch, 2% of polylactic acid toughening agent, 3% of nucleating agent, 2% of lubricant, 2% of catechol, 1% of ethylcellulose, 1% of ultraviolet resistant agent, 2% of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester), 2% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;

wherein, the nucleating agent is 1% of calcium carbonate and 2% of mica.

Example 3:

30% of thermoplastic starch, 2% of polylactic acid toughening agent, 3% of nucleating agent, 2% of lubricant, 2% of catechol, 1% of ethylcellulose, 1% of ultraviolet resistant agent, 2% of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester), 4% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;

wherein, the nucleating agent is 1% of calcium carbonate and 2% of mica.

Example 4:

30% of thermoplastic starch, 2% of polylactic acid toughening agent, 3% of nucleating agent, 2% of lubricant, 2% of catechol, 1% of ethylcellulose, 1% of ultraviolet resistant agent, 3% of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester), 2% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;

wherein, the nucleating agent is 1% of calcium carbonate and 2% of mica.

Example 5:

30% of thermoplastic starch, 2% of polylactic acid toughening agent, 3% of nucleating agent, 2% of lubricant, 2% of catechol, 1% of ethylcellulose, 1% of ultraviolet resistant agent, 3% of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester), 1% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;

wherein, the nucleating agent is 1% of calcium carbonate and 2% of mica.

Comparative example 1:

30% of thermoplastic starch, 2% of polylactic acid toughening agent, 3% of nucleating agent, 2% of lubricant, 2% of catechol, 1% of ethylcellulose, 1% of ultraviolet resistant agent, 2% of poly (3-hydroxybutyrate-3-hydroxycaproic acid ester), 0.5% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;

wherein, the nucleating agent is 1% of calcium carbonate and 2% of mica.

Wherein, the thickness of the fresh-keeping film of each of the examples 1-5 and the comparative example 1 is 12 μm.

Heat shrinkage in MD and TD tests:

the measurement was performed in accordance with ASTM D-2732. In the measurement, a sample of the preservative film was allowed to stand in a constant temperature bath adjusted to a set temperature (130 ℃) for 2 minutes. After 2 minutes, the preservative film was taken out of the thermostat, and the lengths of the marks originally marked within 30 minutes were measured in the flow direction (MD) and the direction perpendicular to the flow direction (TD) in an atmosphere of 50% rh at 23 ℃. At this time, the reduction value from the original length of 10cm was obtained as a percentage of the original length of 10 cm. The percentage obtained was the heat shrinkage.

Table 1: effects of poly (3-hydroxybutyrate-3-hydroxycaproate) and poly (3-hydroxybutyrate-4-hydroxybutyrate) on preservative film performance:

as can be seen from table 1: example 1-example 5 in comparison to comparative example 1, the nucleating agent 3% was calcium carbonate 1% and mica 2% when the mass ratio of poly (3-hydroxybutyrate-3-hydroxycaproate) and poly (3-hydroxybutyrate-4-hydroxybutyrate) was 0.5-3. The mass ratio of the calcium carbonate to the mica is 1:2, and the formula has good heat shrinkage rate, and can be better used in high-temperature environments and the like. Indicating that the proper proportion of the poly (3-hydroxybutyrate-3-hydroxycaproate) and the poly (3-hydroxybutyrate-4-hydroxybutyrate) and the nucleating agent can improve the material performance.

From comparative examples 1 to 5, it is understood that examples 1 and 5 have a better heat shrinkage rate at a mass ratio of poly (3-hydroxybutyrate-3-hydroxyhexanoate) to poly (3-hydroxybutyrate-4-hydroxybutyrate) of 2 to 3, and can be used better under high temperature and other environments, and have a better synergistic effect in a proper range of the ratio of poly (3-hydroxybutyrate-3-hydroxyhexanoate) to poly (3-hydroxybutyrate-4-hydroxybutyrate), so that they are not only degradable, but also have a proper heat shrinkage rate, as compared to examples 2 to 4.

Meanwhile, we used the tests of the biodegradation rates of example 1 to example 5 and comparative example 1: the composting test is carried out by adopting the GB/T19277.1-2011 standard, the biological decomposition rate of the biodegradable low-melting-point hot melt polyester is tested, the performance test is carried out after the biodegradable low-melting-point hot melt polyester is placed for 80 days in the air without carbon dioxide at the temperature of 58 ℃ and the relative humidity of 55%, the biological decomposition rate is obtained, the biological decomposition rates of the examples 1-5 are all more than 80%, and the biological decomposition rate of the comparative example 1 is less than 80%, so that the performance of the biological decomposition rates of the examples 1-5 is better, the biological degradation requirement is met, and the environment is more friendly.

In addition, by controlling the thickness range of the preservative film to be 13-15 μm, we compared the following experiment, the improvement of example 6-example 9 compared with example 4 is only that we optimize the thickness of the preservative film on the basis of example 4, wherein the thickness of the preservative film of example 6 is 13 μm, the thickness of the preservative film of example 7 is 14 μm, the thickness of the preservative film of example 8 is 15 μm, and the thickness of the preservative film of example 9 is 16 μm.

Table 2: the different thickness ranges of the preservative film affect the performance of the preservative film:

as can be seen from table 2: example 6-example 9 compared with example 4, the thickness of the preservative film is in the range of 13-15 μm, the preservative film has better heat shrinkage in MD and TD, and can be better used in high temperature environment, and the like, because TD is smaller, the uniformity in the vertical direction is high and the use experience is high when MD is smaller.

The above description is only a preferred embodiment of the present application, and is not intended to limit the application in any way, and any person skilled in the art may make some changes or modifications to the equivalent embodiments without departing from the scope of the technical solution of the present application, but any simple modification, equivalent changes and modifications to the above embodiments according to the technical substance of the present application fall within the scope of the technical solution of the present application.

Claims

1. A biodegradable plastic wrap comprising: polylactic acid, thermoplastic starch, polylactic acid toughening agent, nucleating agent, lubricant, catechol, ethylcellulose, ultraviolet resistant agent, poly (3-hydroxybutyrate-3-hydroxycaproate) and poly (3-hydroxybutyrate-4-hydroxybutyrate), wherein the mass ratio of poly (3-hydroxybutyrate-3-hydroxycaproate) to poly (3-hydroxybutyrate-4-hydroxybutyrate) is 0.5-3, and the heat shrinkage rate of the preservative film in MD direction at 130 ℃ is below 5%.

2. The biodegradable plastic wrap according to claim 1, characterized in that the mass ratio of poly (3-hydroxybutyrate-3-hydroxyhexanoate) to poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3, and/or,

the poly (3-hydroxybutyrate-3-hydroxyhexanoate) is present in an amount of 2% -3% by mass, based on the total mass of the biodegradable plastic wrap, and/or,

the mass content of the poly (3-hydroxybutyrate-4-hydroxybutyrate) is 1% -4% based on the total mass of the biodegradable preservative film.

3. The biodegradable plastic wrap according to claim 2, characterized in that said nucleating agent comprises talc, calcium carbonate, mica or clay, and/or,

the thickness of the preservative film ranges from 13 mu m to 15 mu m.

4. A method for preparing a biodegradable plastic wrap, for manufacturing the biodegradable plastic wrap of claim 1, comprising the steps of:

5. The method of producing a biodegradable plastic film according to claim 4, wherein the plastic film is stretched in a TD direction during the blow molding process, so that the plastic film has a heat shrinkage rate of 5% or less in the TD direction at 130 ℃.