CN116285277A - Biodegradable preservative film and preparation method thereof - Google Patents

Biodegradable preservative film and preparation method thereof Download PDF

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Publication number
CN116285277A
CN116285277A CN202310540019.4A CN202310540019A CN116285277A CN 116285277 A CN116285277 A CN 116285277A CN 202310540019 A CN202310540019 A CN 202310540019A CN 116285277 A CN116285277 A CN 116285277A
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China
Prior art keywords
hydroxybutyrate
preservative film
polyhydroxyalkanoate
biodegradable
poly
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CN202310540019.4A
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Chinese (zh)
Inventor
宋清魁
赵勇
赵鹏
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Cangzhou Jinsanyang Plastic Industry Co ltd
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Cangzhou Jinsanyang Plastic Industry Co ltd
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Application filed by Cangzhou Jinsanyang Plastic Industry Co ltd filed Critical Cangzhou Jinsanyang Plastic Industry Co ltd
Priority to CN202310540019.4A priority Critical patent/CN116285277A/en
Publication of CN116285277A publication Critical patent/CN116285277A/en
Priority to CN202311048106.4A priority patent/CN116904009A/en
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D7/00—Producing flat articles, e.g. films or sheets
    • B29D7/01—Films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2403/00—Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
    • C08J2403/02—Starch; Degradation products thereof, e.g. dextrin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2467/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/13—Phenols; Phenolates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
    • Y02W90/10—Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics

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 polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate). The mass ratio of the polyhydroxyalkanoate to the poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3. Based on the total mass of the biodegradable preservative film, the mass content of the polyhydroxyalkanoate is 2% -3%. The biodegradable preservative film can improve the biodegradation rate, improve the degradation process of the biodegradable preservative film and meet the environmental protection application.

Description

Biodegradable preservative film and preparation method thereof
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.
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, improve 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 polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate).
In some embodiments, the mass ratio of polyhydroxyalkanoate to poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3.
In some embodiments, the polyhydroxyalkanoate is present in an amount of 2% -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 invention is preferably an ultraviolet absorber UV-531.
In some embodiments, the mass ratio of polyhydroxyalkanoate to poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3.
In some embodiments, the polyhydroxyalkanoate is present in an amount of 2% -3% by mass based on the total mass of the biodegradable wrap.
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, polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate), and 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 comprises polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate), wherein the mass ratio of the polyhydroxyalkanoate 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 met.
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 polyhydroxyalkanoate 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 good biodegradability.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the specific embodiments of the present application, and it is apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in this application 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 polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate).
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 invention is preferably an ultraviolet absorber UV-531.
In some embodiments, the mass ratio of polyhydroxyalkanoate to poly (3-hydroxybutyrate-4-hydroxybutyrate) is 2-3.
In some embodiments, the polyhydroxyalkanoate is present in an amount of 2% -3% by mass based on the total mass of the biodegradable wrap.
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.
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 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.
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 ℃.
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, polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate), and 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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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.
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 polyhydroxyalkanoate, 1% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance of polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;
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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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 polyhydroxyalkanoate, 2% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance of polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;
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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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 polyhydroxyalkanoate, 4% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance of polylactic acid are physically mixed, and then are subjected to 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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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 polyhydroxyalkanoate, 2% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance of polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;
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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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 polyhydroxyalkanoate, 1% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance of polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;
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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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 ethyl cellulose, 1% of ultraviolet resistance agent, 2% of polyhydroxyalkanoate, 0.5% of poly (3-hydroxybutyrate-4-hydroxybutyrate) and the balance of polylactic acid are physically mixed, and then bracing, water cooling and granulating are carried out;
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.
Wherein the ratio of the die opening of the single screw extruder to the bubble tube diameter is selected to be 4:1.
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 polyhydroxyalkanoates and poly (3-hydroxybutyrate-4-hydroxybutyrate) on preservative film performance:
polyhydroxyalkanoate Poly (3-hydroxybutyrate-4-hydroxybutyrate) Heat shrinkage in MD Biological decomposition Rate
Example 1 2% 1% 3% 89%
Example 2 2% 2% 4% 84%
Example 3 2% 4% 4.8% 83%
Example 4 3% 2% 4.2% 81%
Example 5 3% 1% 2% 87%
Comparative example 1 2% 0.5% 10% 75%
As can be seen from table 1: example 1-example 5 compared with comparative example 1, when the mass ratio of polyhydroxyalkanoate to poly (3-hydroxybutyrate-4-hydroxybutyrate) was 0.5-3, it had a better heat shrinkage and could be used more effectively under high temperature and other conditions.
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 polyhydroxyalkanoate to poly (3-hydroxybutyrate-4-hydroxybutyrate) with respect to examples 2 to 3, can be used in a high temperature environment or the like, and have a better synergistic effect in a proper range of polyhydroxyalkanoate to poly (3-hydroxybutyrate-4-hydroxybutyrate) ratio, so that they are not only degradable but also have a proper heat shrinkage rate.
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:
heat shrinkage in MD Heat shrinkage in TD direction
Example 6 3.2% 3.1%
Example 7 2.5% 2.5%
Example 8 2% 4%
Example 9 3.9% 4.8%
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 foregoing description is only a preferred embodiment of the present application and is not intended to limit the present application in any way, and any person skilled in the art may make several 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 matter of the present application still fall within the scope of the technical solution of the present application.

Claims (10)

1. A biodegradable plastic wrap comprising: polylactic acid, thermoplastic starch, polylactic acid toughening agent, nucleating agent, lubricant, catechol, ethylcellulose, ultraviolet resistant agent, polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate), wherein the mass ratio of polyhydroxyalkanoate 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 said polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate) are in a mass ratio of 2-3.
3. The biodegradable plastic wrap according to claim 1, characterized in that the polyhydroxyalkanoate has a mass content of 2% -3% based on the total mass of the biodegradable plastic wrap.
4. The biodegradable plastic wrap according to claim 1, characterized in that the poly (3-hydroxybutyrate-4-hydroxybutyrate) is 1-4% by mass based on the total mass of the biodegradable plastic wrap.
5. The biodegradable wrap according to claim 4, characterized in that said nucleating agent comprises talc, calcium carbonate, mica or clay.
6. The biodegradable wrap according to claim 5, characterized in that said nucleating agent comprises at least two of zinc stearate, magnesium salt, calcium salt, or barium salt, and/or,
the thickness range of the preservative film is 13-15 mu m.
7. The biodegradable plastic wrap according to claim 1, characterized in that said plastic wrap has a heat shrinkage of 5% or less in TD direction at 130 ℃.
8. A method for preparing a biodegradable plastic wrap, for manufacturing the biodegradable plastic wrap of claim 1, comprising the steps of:
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, polyhydroxyalkanoate and poly (3-hydroxybutyrate-4-hydroxybutyrate), and 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.
9. The method of producing a biodegradable plastic film according to claim 8, wherein the plastic film is stretched in the 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 ℃.
10. The method for producing a biodegradable plastic wrap according to claim 8, wherein the stretching and relaxing steps are performed 1 time in the TD direction of the plastic wrap, and the deformation rate in the stretching step is 15%/sec and the relaxing rate is 5%/sec.
CN202310540019.4A 2023-05-15 2023-05-15 Biodegradable preservative film and preparation method thereof Pending CN116285277A (en)

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