CN117534875A - Environment-friendly degradable food-grade plastic packaging film - Google Patents

Environment-friendly degradable food-grade plastic packaging film Download PDF

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CN117534875A
CN117534875A CN202311584469.XA CN202311584469A CN117534875A CN 117534875 A CN117534875 A CN 117534875A CN 202311584469 A CN202311584469 A CN 202311584469A CN 117534875 A CN117534875 A CN 117534875A
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film
polylactic acid
starch
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胡长昕
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Jiangsu Yuhao New Material Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/42—Applications of coated or impregnated materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/46—Applications of disintegrable, dissolvable or edible materials
    • B65D65/466—Bio- or photodegradable packaging materials
    • 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
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/0427—Coating with only one layer of a composition containing a polymer binder
    • 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
    • C08J2303/00—Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
    • C08J2303/02—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
    • C08J2401/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2401/08—Cellulose derivatives
    • C08J2401/26—Cellulose ethers
    • C08J2401/28—Alkyl ethers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • 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
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    • 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
    • C08K5/05—Alcohols; Metal alcoholates
    • C08K5/053—Polyhydroxylic alcohols
    • 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
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    • C08K5/10—Esters; Ether-esters
    • C08K5/11—Esters; Ether-esters of acyclic polycarboxylic acids

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Abstract

The invention discloses an environment-friendly degradable food-grade plastic packaging film, which comprises the following raw materials: carboxymethyl cellulose, corn starch, glycerin, polylactic acid, triethyl citrate, and Olibanum extract. The invention takes the starch as the main raw material, has the characteristics of low price, environmental protection and the like, and the mechanical and physical properties of the starch packaging film are enhanced by adding a certain amount of carboxymethyl cellulose. The prepared starch film is immersed in polylactic acid solution, and polylactic acid is coated on the starch film to reduce the water absorption capacity of the starch film, so that the mechanical property, the water resistance and the thermal stability of the starch film can be obviously improved. Meanwhile, the frankincense extract has antibacterial and antifungal activities, and the triethyl citrate is introduced as a biological plasticizer, so that the antibacterial performance of the membrane material can be improved.

Description

Environment-friendly degradable food-grade plastic packaging film
Technical Field
The invention belongs to the field of high polymer materials, and particularly relates to an environment-friendly degradable food-grade plastic packaging film.
Background
Currently, most commercially available food packaging materials are derived from non-degradable fossil fuels. Today, the production of plastics is over one hundred million tons and plastics for food packaging account for a large proportion. How to treat waste food package becomes a scientific problem, the incineration or landfill method is generally adopted at present, so that serious water quality and soil pollution are caused, dioxin is generated when plastics are incinerated, and the waste food package is a strong cancerogenic substance. Moreover, fossil fuels are non-renewable resources and eventually face the dilemma of resource exhaustion. Food packaging materials are now in the primary stage of the sharp transition to biodegradable plastics, due to the rapid research and development of bio-based packaging caused by severe contamination by non-degradable plastics.
Patent CN 103059325B discloses a preparation method of a novel starch-based cellulose degradable plastic film, and raw material starch can be corn starch, wheat starch, rice starch, sweet potato starch or potato starch, and has wide sources and low price. The polyvinyl alcohol can be used as a reinforcing agent to improve the mechanical properties of the degradable plastic. The cellulose acetate is prepared from cotton fibers and crosslinked with starch to prepare a degradable plastic film, the crosslinking agent is tributyl citrate, the catalyst is concentrated sulfuric acid, and the prepared degradable plastic film has excellent mechanical properties and high degradation speed; the preparation method of the degradable plastic film is simple and easy to operate.
The main raw material starch of the degradable plastic film prepared by the invention is taken as a degradable thermoplastic polymer, and the starch-based material reduces the influence of the use of synthetic plastics and non-renewable resources on the environment. The starch-based film is a novel film material which is proposed in recent years, and has wide application prospect in food packaging due to the characteristics of low price, environmental friendliness and the like. The starch film has low cost and convenient production, but the mechanical and physical properties of the starch film are deteriorated when the starch film is contacted with water, and the contact of part of food packages with water is an unavoidable problem, which limits the use of the starch film.
Therefore, how to improve the mechanical and physical properties of starch-based plastic packaging films after contact with water is a technical problem that is currently being urgently solved.
Disclosure of Invention
In view of the above-mentioned drawbacks in view of the prior art, the technical problem to be solved by the present invention is to improve the mechanical and physical properties of plastic packaging films, while imparting excellent degradability and antibacterial properties to the plastic packaging films.
In order to achieve the above purpose, the invention provides an environment-friendly degradable food-grade plastic packaging film.
The technical scheme adopted by the invention is as follows:
an environment-friendly degradable food-grade plastic packaging film is composed of the following raw materials: carboxymethyl cellulose, corn starch, glycerol, and polylactic acid.
The environment-friendly degradable food-grade plastic packaging film also comprises the following raw materials in parts by weight:
triethyl citrate, boswellia carterii extract.
Preferably, the environment-friendly degradable food-grade plastic packaging film comprises the following raw materials in parts by weight:
15-20 parts by weight of carboxymethyl cellulose, 30-60 parts by weight of corn starch, 3-6 parts by weight of glycerol and 5-20 parts by weight of polylactic acid.
More preferably, the environment-friendly degradable food-grade plastic packaging film further comprises the following raw materials in parts by weight:
3 to 6 weight portions of triethyl citrate and 0.5 to 1 weight portion of frankincense extract.
The environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 30-60 parts by weight of corn starch, 15-20 parts by weight of carboxymethyl cellulose and 3-6 parts by weight of glycerol, adding 60-80 parts by weight of water, stirring uniformly, heating to 60-80 ℃ and stirring for 2-4 hours, uniformly pouring the mixture on a flat glass plate, drying at room temperature, and peeling off from the glass plate; preparing a starch film;
dissolving 5-20 parts by weight of polylactic acid in 80-100 parts by weight of chloroform, magnetically stirring for 2-4 hours to prepare polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to the bath ratio of 100-200 g/L, taking out the film after 2-4 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained.
Preferably, the environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 30-60 parts by weight of corn starch, 15-20 parts by weight of carboxymethyl cellulose, 3-6 parts by weight of glycerol, 3-6 parts by weight of triethyl citrate and 0.5-1 part by weight of frankincense extract, adding water, stirring uniformly, heating to 60-80 ℃ and stirring for 2-4 hours, uniformly pouring the mixture on a flat glass plate, drying at room temperature, and peeling off the glass plate to prepare a starch film;
dissolving 20-50 parts by weight of polylactic acid in 80-100 parts by weight of chloroform, magnetically stirring for 2-4 hours to prepare polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to the bath ratio of 100-200 g/L, taking out the film after 2-4 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained.
Most preferably, the environment-friendly degradable food-grade plastic packaging film comprises the following raw materials in parts by weight:
15 to 20 weight parts of carboxymethyl cellulose, 30 to 60 weight parts of corn starch, 3 to 6 weight parts of glycerol, 5 to 20 weight parts of modified polylactic acid, 3 to 6 weight parts of triethyl citrate and 0.5 to 1 weight part of frankincense extract.
The environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 30-60 parts by weight of corn starch, 15-20 parts by weight of carboxymethyl cellulose, 3-6 parts by weight of glycerol, 3-6 parts by weight of triethyl citrate and 0.5-1 part by weight of frankincense extract, adding water, stirring uniformly, heating to 60-80 ℃ and stirring for 2-4 hours, uniformly pouring the mixture on a flat glass plate, drying at room temperature, and peeling off the glass plate to prepare a starch film;
dissolving 20-50 parts by weight of modified polylactic acid in 80-100 parts by weight of chloroform, magnetically stirring for 2-4 hours to prepare a polylactic acid solution, immersing the prepared starch film into the modified polylactic acid solution according to a bath ratio of 100-200 g/L, taking out the film after 2-4 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained.
The thickness of the environment-friendly degradable food-grade plastic packaging film is 1-100 um.
The preparation method of the modified polylactic acid comprises the following steps:
the polylactic acid is dried in vacuum for 12 hours at 50 ℃, and the dried polylactic acid and the 1.5wt percent of the styrene-acrylic acid multifunctional epoxy oligomer chain extender are fully mixed by a high-speed mixer, wherein the rotating speed of the mixer is 2500r/min, and the mixing time is 3min. Placing the mixture into a double screw extruder, wherein the treatment temperature of the sample is 168-196 ℃, extruding the mixture after melt blending, and the extrusion temperature is 165-185 ℃, thus obtaining the modified polylactic acid.
The invention researches an environment-friendly degradable food-grade plastic packaging film. Starch is used as a main raw material, and the starch is used as a degradable thermoplastic polymer, so that the starch has wide application potential in food packaging due to the characteristics of low price, environmental friendliness and the like. However, starch can deteriorate its mechanical and physical properties upon contact with water, which limits the application of starch films. The inventor enhances the mechanical and physical properties of the packaging film by adding certain carboxymethyl cellulose, because the molecular chain structure of the carboxymethyl cellulose (CMC) is similar to starch, and can be well integrated into a starch solution system, and a space rigid network structure is formed through hydrogen bonds. However, the introduction of carboxymethyl cellulose results in poor flexibility of the plastic film and reduced elongation at break. Further raw materials are introduced with glycerol, the glycerol serving as a polyhydric alcohol of small molecules can be diffused into a starch molecular chain to break hydrogen bonds on the starch chain, so that interaction among starch macromolecules is reduced, the breaking of starch granule structures is promoted, the starch molecules are easier to disperse due to the existence of the glycerol, the activity of the whole macromolecule chain is improved, and the total plasticity of the membrane is improved.
Typically, starch films have deteriorated mechanical and physical properties upon contact with water in order to further enhance the mechanical and physical properties of the packaging film. The inventor immerses the prepared starch film in polylactic acid solution according to the bath ratio of 100-200 g/L, and polylactic acid is coated on the starch film to reduce the water absorption capacity of the starch film, so that the mechanical property and the thermal stability of the starch film can be obviously improved. Simultaneously, the frankincense extract is introduced to have antibacterial and antifungal activities, and the triethyl citrate is introduced to be used as a biological plasticizer, wherein the frankincense extract contains active ingredients capable of adjusting the characteristics of the triethyl citrate when being combined with a starch film. The addition of the olibanum extract makes the surface of the film uniform, because the olibanum extract promotes the dissolution performance of the triethyl citrate in the starch, so that the crosslinking is more complete, and the uneven polymer structure caused by raw material agglomeration is reduced, thereby improving the antibacterial performance of the film material.
However, polylactic acid is easy to be hydrolyzed and degraded, which is one of the most critical defects of polylactic acid, so that the environment-friendly degradable food-grade plastic packaging film also has the defect of poor hydrolysis resistance. The inventors have found out through a number of experiments that by modifying polylactic acid with a chain extender, by adding the chain extender during melt processing, the reactive ends of the polymer chains are linked together, and a polymer of higher molecular weight can be obtained. Solves the problem of poor hydrolysis resistance of the degradable food-grade plastic packaging film.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the prior art, the plastic packaging film takes starch as a raw material, and has good degradability.
2. Compared with the prior art, the raw materials for preparing the plastic packaging film contain carboxymethyl cellulose and glycerol, so that the physical and mechanical properties of the plastic packaging film are further improved.
3. Compared with the prior art, the prepared starch film is immersed into polylactic acid solution according to the bath ratio of 100-200 g/L, and polylactic acid is coated on the starch film to reduce the water absorption capacity of the starch film, so that the mechanical property, the water resistance and the thermal stability of the starch film can be obviously improved.
4. Compared with the prior art, the antibacterial property of the film material can be improved by the frankincense extract and the triethyl citrate in the plastic packaging film.
5. Compared with the prior art, the polylactic acid modified by the chain extender solves the problem of poor hydrolysis resistance of the degradable food grade plastic packaging film.
Detailed Description
The raw material sources in the examples are as follows:
corn starch: CAS number; 9005-25-8.
Carboxymethyl cellulose: CAS number; 9004-32-4, specification m.w.700000 (ds=0.9), 2500-4500mpa.s.
Glycerol: CAS number; 56-81-5.
Polylactic acid: CAS number; 26100-51-6, molecular weight 60000.
Triethyl citrate: CAS number; 77-93-0.
The preparation method of the olibanum extract comprises the following steps: 200g of olibanum resin is weighed into a 3L distillation flask, 2L of water is added for soaking for 6 hours, the distillation flask is heated, the temperature of a distillation kettle is 220 ℃, the extraction time is 5 hours, steam generated during distillation rises and flows back when meeting a condensing pipe, an oil-water mixture is divided into two layers by an integral separating funnel, a rotary piston is rotated to discharge lower water, and the upper layer is collected to obtain the olibanum extract.
Styrene-acrylic multifunctional epoxy oligomer chain extender: the multifunctional epoxy oligomer of styrene-acrylic acid, which is purchased from basf company of united states, is used as a chain extender and has an epoxy equivalent weight of 445g/mol.
Example 1
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose and 4 parts by weight of glycerol, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
dissolving 5 parts by weight of polylactic acid in 100 parts by weight of chloroform, magnetically stirring for 3 hours to prepare a polylactic acid solution, immersing a prepared starch film into the polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Example 2
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose and 4 parts by weight of glycerol, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
10 parts by weight of polylactic acid is dissolved in 100 parts by weight of chloroform, magnetic stirring is carried out for 3 hours to prepare polylactic acid solution, the prepared starch film is immersed into the polylactic acid solution according to the bath ratio of 150g/L, and after 3 hours, the film is taken out and naturally dried; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Example 3
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose and 4 parts by weight of glycerol, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
dissolving 15 parts by weight of polylactic acid in 100 parts by weight of chloroform, magnetically stirring for 3 hours to prepare a polylactic acid solution, immersing a prepared starch film into the polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Example 4
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose and 4 parts by weight of glycerol, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
dissolving 20 parts by weight of polylactic acid in 100 parts by weight of chloroform, magnetically stirring for 3 hours to prepare a polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Example 5
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose, 4 parts by weight of glycerol, 4 parts by weight of triethyl citrate and 0.8 part by weight of frankincense extract, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
dissolving 20 parts by weight of polylactic acid in 100 parts by weight of chloroform, magnetically stirring for 3 hours to prepare a polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Example 6
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose, 4 parts by weight of glycerol, 4 parts by weight of triethyl citrate and 0.8 part by weight of frankincense extract, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, continuously stirring for 3 hours, uniformly pouring the mixture on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off the glass plate to obtain a starch film;
dissolving 20 parts by weight of modified polylactic acid in 100 parts by weight of chloroform, stirring for 3 hours to prepare a modified polylactic acid solution, immersing a prepared starch film into the modified polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
The preparation method of the modified polylactic acid comprises the following steps:
vacuum drying polylactic acid at 50 ℃ for 12 hours, mixing the dried polylactic acid and 1.5wt% of a styrene-acrylic acid multifunctional epoxy oligomer chain extender by a high-speed mixer, wherein the rotating speed of the high-speed mixer is 2500r/min, and the mixing time is 3min; and (3) placing the mixture in a double-screw extruder, wherein the treatment temperature of the sample is 190 ℃, extruding after melt blending, and the extrusion temperature is 180 ℃, thus obtaining the modified polylactic acid.
Comparative example 1
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose, 4 parts by weight of glycerol, 4 parts by weight of triethyl citrate and 0.8 part by weight of frankincense extract, adding 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain the environment-friendly degradable food-grade plastic packaging film, wherein the thickness of the packaging film is 60 microns.
Comparative example 2
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose, 4 parts by weight of glycerol and 4 parts by weight of triethyl citrate, adding 70 parts by weight of water, stirring uniformly, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
dissolving 20 parts by weight of polylactic acid in 100 parts by weight of chloroform, magnetically stirring for 3 hours to prepare a polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Comparative example 3
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 40 parts by weight of corn starch, 17 parts by weight of carboxymethyl cellulose, 4 parts by weight of glycerol and 0.8 part by weight of frankincense extract, adding 70 parts by weight of water, stirring uniformly, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain a starch film;
dissolving 20 parts by weight of polylactic acid in 100 parts by weight of chloroform, magnetically stirring for 3 hours to prepare a polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to a bath ratio of 150g/L, taking out the film after 3 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained, and the thickness of the packaging film is 60 mu m.
Comparative example 4
An environment-friendly degradable food-grade plastic packaging film is prepared by the following method:
adding 70 parts by weight of corn starch into 70 parts by weight of water, uniformly stirring, heating to 70 ℃, stirring for 3 hours, uniformly pouring on a flat glass plate, drying at 25 ℃ for 5 hours, and peeling off from the glass plate to obtain the environment-friendly degradable food-grade plastic packaging film, wherein the thickness of the packaging film is 60 microns.
Test example:
1. tensile Property test
Referring to astm d882-02, the test film was cut into strips of 140mm length and 15mm width, equilibrated for 48h in an environment at 25±1 ℃ and 50±1% humidity, and tested for mechanical properties on an electronic universal tester, test additions were: stretching 50mm/min, initial spacing 100mm, and calculating to obtain tensile strength (TS, MPa) and elongation at break (EAB,%) according to formulas (1) and (2).
Equation (1) ts=f/S;
equation (2) eab= (L-L) 0 )/L 0 ×100％
Wherein: f, maximum tensile force and N when the film breaks; s-cross sectional area at break of film, mm 2 The method comprises the steps of carrying out a first treatment on the surface of the Length of L-membrane at break, mm; l (L) 0 Initial length of film, mm.
Table 1: tensile Property test results
Sample of Tensile strength, MPa Fracture ofElongation%
Example 1 12.63 5.24
Example 2 16.36 10.32
Example 3 18.23 9.42
Example 4 19.36 9.12
Example 5 24.14 14.25
Example 6 26.45 16.23
Comparative example 1 8.32 3.12
Comparative example 2 18.56 11.23
Comparative example 3 16.48 10.89
Comparative example 4 5.63 2.31
By comparing examples 1 to 4 with comparative example 1, examples 1 to 4 prepared starch films were immersed in a polylactic acid solution, and polylactic acid was coated on the starch films to reduce water absorption capacity thereof, and tensile strength and elongation at break of the starch films could be significantly improved.
Further, by comparing example 5 with comparative example 3, the addition of triethyl citrate in the process of producing the packaging film of example 5 significantly improved the tensile strength and elongation at break of the packaging film. The reason is that triethyl citrate has good compatibility with starch and high plasticizing efficiency.
2. Degradation Performance test
The experiment adopts a soil burying method to study the degradation performance of the membrane material. Preparation of 1X 1cm 2 Test sample film of size, sample film dried under vacuum to constant weight and mass m measured 0 Placing the sample film in the sludge turbid liquid, taking out the sample every 20 days, cleaning, drying for 12h, and weighing again for m g The mass loss rate of the composite material in soil is taken as a calculation formula for evaluating the degradability of the composite material:
degradation rate= (m 0 -m g )/m 0 ×100％。
Table 2: degradation Performance test results
Sample of Degradation rate, percent
Example 2 32.1
Example 5 46.3
Comparative example 2 56.1
By comparing example 5 with example 2 and comparative example 2, the addition of triethyl citrate and Olibanum extract in the process of preparing packaging film in example 5 significantly improves the degradation performance of packaging film. The degradation performance of comparative example 2 is higher than that of example 5 because the addition of the boswellia extract has an antibacterial effect, and the soil buried degradation degree is lower than that of the film without the addition of the boswellia extract.
3. Antibacterial property test
Reference standard GB T31402-2015.
Materials and experimental conditions
The reproducibility test was performed on both samples in all 3 laboratories participating in the inter-laboratory test. The number of samples used in each stage complies with the present standard requirements. Samples, strains, culture media, etc. are provided to each laboratory prior to testing.
Table 3: antibacterial property test results
Sample of Average antibacterial property
Example 2 3.21
Example 5 5.24
Comparative example 1 1.14
By comparing example 5, example 2 and comparative example 1, the triethyl citrate and the olibanum extract are added in the process of preparing the packaging film in example 5 to synergistically improve the antibacterial property of the packaging film obviously.
4. Hydrolysis resistance test
The test samples of examples 5 and 6 were put in a constant temperature and humidity machine for hydrolysis reaction, and after one week were taken out and tested for tensile properties; the test conditions were 65℃and 95% humidity.
Table 4: tensile Property test results after hydrolysis
Sample of Tensile strength, MPa Elongation at break%
Example 5 10.21 6.23
Example 6 22.53 13.25
The degradation of polylactic acid may be due to hydrolysis caused by the presence of water, which permeates into the amorphous region of the polymer matrix and then randomly reacts with one ester bond on the polylactic acid chain to form two short chains, the terminal carboxyl and hydroxyl groups, and the cleavage of the polylactic acid chain may break the long chains into smaller fragments, thereby producing water-soluble oligomers and monomers.
By comparing example 5 with example 6, example 6 prepared modified polylactic acid by adding a chain extender styrene-acrylic acid multifunctional epoxy oligomer during melt processing, the mechanical properties of the modified polylactic acid are basically unchanged after hydrolysis when the modified polylactic acid is applied to preparing an environment-friendly degradable food grade plastic packaging film. The reason for this is that the chain extender links the carboxyl group and the hydroxyl group of the polylactic acid chain, and a polymer having a higher molecular weight can be obtained, and a water-insoluble soluble oligomer is formed even if the polylactic acid chain breaks.
5. Evaluation of food safety
Evaluation criteria: GB 15193.1-2014 national food safety standard food safety toxicology evaluation program
The environment-friendly degradable food-grade plastic packaging film prepared by the invention passes through the food safety toxicology evaluation program test and accords with the national food safety standard.
The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention by one of ordinary skill in the art without undue burden. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.

Claims (8)

1. The environment-friendly degradable food-grade plastic packaging film is characterized by comprising the following raw materials: carboxymethyl cellulose, corn starch, glycerol, and polylactic acid.
2. The environmentally friendly degradable food-grade plastic packaging film of claim 1, wherein said raw materials further comprise:
triethyl citrate, boswellia carterii extract.
3. The environment-friendly degradable food-grade plastic packaging film is characterized by comprising the following raw materials in parts by weight:
15-20 parts by weight of carboxymethyl cellulose, 30-60 parts by weight of corn starch, 3-6 parts by weight of glycerol and 5-20 parts by weight of polylactic acid.
4. The environmentally friendly degradable food-grade plastic packaging film of claim 3, wherein the raw materials in parts by weight further comprise:
3 to 6 weight portions of triethyl citrate and 0.5 to 1 weight portion of frankincense extract.
5. The environmentally friendly degradable food-grade plastic packaging film of claim 3, wherein the environmentally friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 30-60 parts by weight of corn starch, 15-20 parts by weight of carboxymethyl cellulose and 3-6 parts by weight of glycerol, adding 60-80 parts by weight of water, stirring uniformly, heating to 60-80 ℃ and stirring for 2-4 hours, uniformly pouring the mixture on a flat glass plate, drying at room temperature, and peeling off from the glass plate; preparing a starch film;
dissolving 5-20 parts by weight of polylactic acid in 80-100 parts by weight of chloroform, magnetically stirring for 2-4 hours to prepare polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to the bath ratio of 100-200 g/L, taking out the film after 2-4 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained.
6. The environmentally friendly degradable food-grade plastic packaging film of claim 4, wherein the environmentally friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 30-60 parts by weight of corn starch, 15-20 parts by weight of carboxymethyl cellulose, 3-6 parts by weight of glycerol, 3-6 parts by weight of triethyl citrate and 0.5-1 part by weight of frankincense extract, adding water, stirring uniformly, heating to 60-80 ℃ and stirring for 2-4 hours, uniformly pouring the mixture on a flat glass plate, drying at room temperature, and peeling off the glass plate to prepare a starch film;
dissolving 20-50 parts by weight of polylactic acid in 80-100 parts by weight of chloroform, magnetically stirring for 2-4 hours to prepare polylactic acid solution, immersing the prepared starch film into the polylactic acid solution according to the bath ratio of 100-200 g/L, taking out the film after 2-4 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained.
7. An environment-friendly degradable food-grade plastic packaging film is characterized by comprising the following raw materials in parts by weight:
15 to 20 weight parts of carboxymethyl cellulose, 30 to 60 weight parts of corn starch, 3 to 6 weight parts of glycerol, 5 to 20 weight parts of modified polylactic acid, 3 to 6 weight parts of triethyl citrate and 0.5 to 1 weight part of frankincense extract.
8. The environmentally friendly degradable food-grade plastic packaging film of claim 7, wherein the environmentally friendly degradable food-grade plastic packaging film is prepared by the following method:
mixing 30-60 parts by weight of corn starch, 15-20 parts by weight of carboxymethyl cellulose, 3-6 parts by weight of glycerol, 3-6 parts by weight of triethyl citrate and 0.5-1 part by weight of frankincense extract, adding water, stirring uniformly, heating to 60-80 ℃ and stirring for 2-4 hours, uniformly pouring the mixture on a flat glass plate, drying at room temperature, and peeling off the glass plate to prepare a starch film;
dissolving 20-50 parts by weight of modified polylactic acid in 80-100 parts by weight of chloroform, magnetically stirring for 2-4 hours to prepare a polylactic acid solution, immersing the prepared starch film into the modified polylactic acid solution according to a bath ratio of 100-200 g/L, taking out the film after 2-4 hours, and naturally airing; the environment-friendly degradable food-grade plastic packaging film is obtained.
CN202311584469.XA 2023-11-25 2023-11-25 Environment-friendly degradable food-grade plastic packaging film Withdrawn CN117534875A (en)

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