CN115416385A - Biodegradable heat shrinkable film and preparation method thereof - Google Patents

Biodegradable heat shrinkable film and preparation method thereof Download PDF

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CN115416385A
CN115416385A CN202211061058.8A CN202211061058A CN115416385A CN 115416385 A CN115416385 A CN 115416385A CN 202211061058 A CN202211061058 A CN 202211061058A CN 115416385 A CN115416385 A CN 115416385A
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shrinkable film
heat shrinkable
content
layer structure
biodegradable
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陈雷
刘建
李平
尚祖明
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Kanghui New Material Technology Co Ltd
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Kanghui New Material Technology Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/065—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
    • B32B5/20—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material foamed in situ
    • 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
    • B65D65/40—Applications of laminates for particular packaging purposes
    • 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
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2266/00—Composition of foam
    • B32B2266/02—Organic
    • B32B2266/0214—Materials belonging to B32B27/00
    • B32B2266/0264—Polyester
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/72—Density
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/724—Permeability to gases, adsorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/746—Slipping, anti-blocking, low friction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2439/00—Containers; Receptacles
    • B32B2439/70—Food packaging
    • 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
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2467/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • 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
    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives
    • 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
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Materials Engineering (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Biological Depolymerization Polymers (AREA)
  • Wrappers (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

Abstract

The invention relates to a biodegradable heat shrinkable film and a preparation method thereof, the biodegradable heat shrinkable film comprises an outer layer structure consisting of an upper surface layer and a lower surface layer and an inner layer structure consisting of a core layer, and the preparation raw materials of the outer layer structure comprise: at least one biodegradable polyester, a nucleating agent, nano-silica, a lubricant; the preparation raw materials of the inner layer structure comprise: polylactic acid, polybutylene succinate, polybutylene terephthalate-adipate, a toughening agent and a chain extender, and aims to meet the requirement of biodegradability by using a full-biodegradable material on the basis of meeting the application of packaging of a heat shrinkable film, reduce the density by a micro-foaming technology, and enable the heat shrinkable film to have a core layer cell structure so as to improve the water vapor permeability and further meet the requirement of packaging of fresh fruits and vegetables.

Description

Biodegradable heat shrinkable film and preparation method thereof
Technical Field
The invention belongs to the technical field of plastic processing, and particularly relates to a biodegradable heat shrinkable film and a preparation method thereof.
Background
The heat shrinkable film is widely applied to various fields in life and is an indispensable part of packaging materials, but the conventional heat shrinkable film brings convenience to people and causes serious pollution to the environment, and the light breathable biodegradable heat shrinkable film can be completely biodegraded, so that the heat shrinkable film is a clean and environment-friendly packaging material.
With the development of science and technology, biodegradable heat-shrinkable films are also appeared in the market, and the biodegradable heat-shrinkable films have high raw material cost, high production cost, high density and high use cost, so that people are forbidden to use the biodegradable heat-shrinkable films.
The existing mature heat shrinkable films generally have different thicknesses of 20-80 mu m, have large barrier property and poor air permeability and cannot be used for packaging fresh fruits and vegetables.
Disclosure of Invention
The invention mainly aims at the problems, provides a biodegradable heat shrinkable film and a preparation method thereof, and aims to meet the requirement of biodegradability by using a full-biodegradable material on the basis of meeting the application of heat shrinkable film packaging, and reduce the density by a micro-foaming technology to ensure that the heat shrinkable film has a core layer cellular structure so as to improve the water vapor permeability.
In order to achieve the above object, the present invention provides a biodegradable heat shrinkable film, which comprises an outer layer structure composed of an upper surface layer and a lower surface layer, and an inner layer structure composed of a core layer, wherein the outer layer structure is prepared from the following raw materials: at least one biodegradable polyester, a nucleating agent, nano-silica, a lubricant; the preparation raw materials of the inner layer structure comprise: polylactic acid, polybutylene succinate, polybutylene terephthalate-adipate, a toughening agent and a chain extender.
Furthermore, the total mass of the prepared outer layer structure accounts for 10-30%, and the total mass of the prepared inner layer structure accounts for 70-90%.
In order to achieve the purpose, the invention provides a preparation method of a biodegradable heat shrinkable film, which is characterized by comprising the following steps of:
s01: manufacturing A master batch: adding the preparation raw material of the outer layer structure into a screw extruder to obtain master batch A;
s02: b, manufacturing master batch: adding the preparation raw materials of the inner layer structure into a screw extruder to obtain B master batches;
s03: casting sheets: putting the A master batch and the B master batch obtained by the processing of the steps S01 and S02 into an ABA three-layer co-extrusion casting machine to finally obtain a sheet consisting of an upper surface layer, a core layer and a lower surface layer, wherein a foaming agent is introduced into a co-extrusion screw rod in which the B master batch is put;
s04: stretching to form a film: and (4) performing biaxial stretching on the sheet processed in the step S03 to obtain the biodegradable heat shrinkable film with high air permeability.
Further, in the step S01, the preparing raw material for preparing the a master batch further includes adding an antioxidant into the screw extruder.
Further, in the step S02, the preparing raw material for preparing the B master batch further includes adding an antioxidant into the screw extruder.
Further, in step S04, the step of stretching to form a film further includes: heating the sheet processed in the step S03 to 75 ℃ to enable the polymer in the sheet to be in a high-elasticity state; and (4) cooling the stretched sheet material suddenly.
Further, in the step S03, the introduced foaming agent is supercritical carbon dioxide or nitrogen.
Further, in step S03, the pore size of the micro pores of the core layer of the sheet is 3-15 μm.
Further, in the step S01, the at least one biodegradable polyester is polylactic acid with the content of 95-98 parts, the content of nucleating agent is 0.3-1 part, the content of nano silicon dioxide is 0.5-2 parts, the content of lubricant is 0.3-1 part, and the content of antioxidant is 0.3-0.8 part.
Further, in the step S02, the content of polylactic acid is 70-90 parts, the content of polybutylene succinate is 0-15 parts, the content of polybutylene terephthalate-adipate is 0-15 parts, the content of flexibilizer is 0.5-3 parts, the content of chain extender is 0.1-0.5 part, and the content of antioxidant is 0.2-1 part.
The technical scheme of the invention has the following advantages: the heat shrinkable film is formed by compounding three layers of ABA, is different from a conventional heat shrinkable film in that an outer layer structure is used as a surface layer of the heat shrinkable film and has the characteristics of smoothness, heat shrinkability, openability and printability, and an inner layer structure is a micro-foaming layer and is used as a core layer of the heat shrinkable film, so that the heat shrinkable film has the characteristics of heat shrinkability, air permeability and low density and can be used for packaging fresh fruits and vegetables.
Drawings
FIG. 1 is a schematic structural view of a biodegradable heat shrinkable film according to an embodiment of the present invention;
in the figure: 1. an upper surface layer; 2. a core layer; 3. and (4) a lower surface layer.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings, which are based on the orientations and positional relationships indicated in the drawings, and are used for convenience in describing the present invention and for simplicity in description, but do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In one aspect of the present invention, a method for preparing a biodegradable heat shrinkable film is provided. The biodegradable heat shrinkable film prepared by the method has the physicochemical characteristics of biodegradability and water vapor permeability.
In the method of the invention, the decomposition time of the formed heat shrinkable film in the external environment can be regulated and controlled by regulating and controlling the proportion of the mixed mixture. Further, according to the method of the present invention, the actual density of the produced heat shrinkable film can be made much lower than the theoretical density thereof, and a heat shrinkable film having a low density, a light weight and a high air permeability can be obtained. The heat shrinkable film formed by the method of the present invention has high air permeability, and thus can be used for packaging fresh fruits and vegetables.
The film structure designed by the invention is an ABA three-layer composite structure, wherein the layer A is an outer layer structure consisting of an upper surface layer 1 and a lower surface layer 3, and the layer B is an inner layer structure consisting of a core layer 2.
The method for preparing the biodegradable heat shrinkable film can comprise the following steps, but is not limited thereto.
First, an a-masterbatch is prepared, and the a-masterbatch may include, but is not limited to, at least one biodegradable polyester, a nucleating agent, nanosilica, a lubricant.
Examples of the at least one biodegradable polyester include, but are not limited to, polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxybutyrate (PHB), PPC, and PCL.
The master batch A can be prepared by a method, and the method can comprise the following steps: adding polylactic acid (PLA), a nucleating agent, silicon dioxide, a lubricant and an antioxidant into a blender, stirring and mixing at a rotating speed of 100-200rpm, then sending to a screw extruder, and extruding and granulating at 120-220 ℃ to obtain the compound A master batch.
Preparing B master batch, wherein the B master batch can comprise, but is not limited to, polylactic acid (PLA), polybutylene succinate (PBS), polybutylene terephthalate-adipate (PBAT), a toughening agent and a chain extender.
The B masterbatch can be prepared by a method, which comprises the following steps: adding polylactic acid (PLA), polybutylene succinate (PBS), polybutylene terephthalate (PBAT), a toughening agent and a chain extender into a blender, stirring and mixing at the rotating speed of 100-200rpm, then conveying to a screw extruder, and extruding and granulating at the temperature of 110-220 ℃ to obtain the compound B master batch.
And then, putting the compound A master batch and the compound B master batch into an ABA three-layer co-extrusion casting machine to finally obtain a sheet sequentially consisting of an upper surface layer, a core layer and a lower surface layer, wherein a foaming agent is introduced into a co-extrusion screw rod which is put into the B master batch to ensure that the core layer has excellent air permeability. In a particular embodiment, the blowing agent introduced is supercritical carbon dioxide or nitrogen, but is not limited thereto.
And after the sheet is formed, stretching the sheet to obtain the biodegradable heat-shrinkable film with high air permeability.
In the method for preparing the highly breathable biodegradable heat shrinkable film of the present invention, the manner of feeding the composite a masterbatch and the composite B masterbatch into an ABA three-layer co-extrusion casting machine to form the highly breathable biodegradable heat shrinkable film is not particularly limited.
In one embodiment, the film structure designed by the invention is an ABA three-layer composite structure, and the outer layer structure takes polylactic acid (PLA) as a base material and is added with a nucleating agent, silicon dioxide, a lubricant and an antioxidant. The polylactic acid, PLA, material has a Tg of 57 ℃, where stated, the Tg represents the temperature at which the polymer transitions from a glassy state to a highly elastic state. The base material is heated to 75 ℃ and is in a high-elastic state of the PLA material, the obtained sheet is subjected to biaxial stretching and then is cooled down suddenly, the stretched membrane is frozen to normal temperature, the membrane has thermal shrinkage at this time, the added nucleating agent and silicon dioxide enable the material to be cooled and crystallized, the materials are not easy to stick to each other when being wound quickly, the silicon dioxide endows the surface of the material with certain roughness, new brush adhesiveness is provided for the material, the lubricant provides processing fluidity, and the antioxidant prevents the membrane from yellowing.
The inner layer structure takes high-content polylactic acid (PLA) and a certain content of polybutylene succinate (PBS) and polybutylene terephthalate (PBAT) as base materials, a toughening agent, a chain extender and an antioxidant are added, and toughness, viscosity and melt strength are increased for the polylactic acid (PLA) material in a multi-component mixing mode, so that bubbles generated by the inner layer structure are small in hole, dense, uniform and free of bubble breakage. Before the extrusion of the co-extrusion casting machine, the inner layer structure takes supercritical carbon dioxide/nitrogen introduced by a screw as a foaming agent, so that the purposes of no toxicity, no harm, small, dense and uniform cells are achieved.
In a specific embodiment, the total mass ratio of the outer layer structure is 10-30%, the total mass ratio of the inner layer structure is 70-90%, the material composition of the upper surface layer and the lower surface layer of the outer layer structure is the master batch A, and the material composition of the core layer of the inner layer structure is the master batch B.
The pore size of the core layer micropores of the biodegradable heat shrinkable film with high air permeability formed by any method for preparing the film is 3-15 microns; the thickness of the stretched film sheet is 25 μm to 50 μm. Therefore, the biodegradable heat shrinkable film has the advantages of good heat shrinkable performance, complete biodegradation, low density, high air permeability and the like.
In yet another aspect of the present invention, a highly breathable biodegradable heat shrinkable film is provided, which has the characteristics of environmental friendliness, no pollution, etc., and can be used as a clean and environment-friendly packaging material. The heat shrinkable film has low density, high water vapor permeability and light weight, so that fresh fruits and vegetables can be packaged.
The following examples are presented to further illustrate the nature of the invention. All proportions quoted are in parts by weight. It is to be understood that the invention is not limited to the specific conditions or details set forth in these examples, except as indicated by the following claims.
The first embodiment is as follows:
the biodegradable heat shrinkable film is divided into an ABA three-layer structure shown in figure 1, wherein an outer layer structure has the characteristics of smoothness, heat shrinkability, openability and printability, and an inner layer structure is a micro-foaming layer and has the characteristics of heat shrinkability, air permeability and low density and is used as a core layer of the heat shrinkable film.
The total mass of the outer layer structure accounts for 10%, the total mass of the inner layer structure accounts for 90%, and the material components of the outer layer structure and the inner layer structure are respectively A master batch and B master batch.
The master batch A comprises the following raw materials in parts by weight: 95 parts of polylactic acid PLA, 0.3 part of NA-305 nucleating agent, 0.5 part of nano silicon dioxide, 0.3 part of lubricant and 0.3 part of antioxidant.
The master batch B comprises the following raw materials in parts by weight: 90 parts of polylactic acid (PLA), 15 parts of polybutylene succinate (PBS), 15 parts of polybutylene terephthalate-adipate (PBAT), 3 parts of a toughening agent, 0.5 part of a chain extender and 1 part of an antioxidant.
The following is a processing method of the heat shrinkable film:
the raw materials A and B are processed into master batches A and B through a double-screw extruder, and the process is shown in table 1.
And then putting the master batches A and the master batches B into an ABA three-layer co-extrusion casting machine, introducing supercritical carbon dioxide/nitrogen into a screw B, and processing into a sheet with the thickness of 400 mu m, wherein the process is shown in Table 2.
The processed sheet is placed into a biaxial stretching machine for biaxial stretching, and a light breathable biodegradable heat-shrinkable film with the thickness of 28 microns can be processed, wherein the light breathable biodegradable heat-shrinkable film has the characteristics of good heat-shrinkable performance, complete biodegradation, low density and high breathability, and the process is shown in the table 3.
TABLE 1
Figure BDA0003826179940000071
TABLE 2
Figure BDA0003826179940000072
TABLE 3
Figure BDA0003826179940000081
The second embodiment:
the biodegradable heat shrinkable film is divided into an ABA three-layer structure shown in figure 1, wherein an outer layer structure has the characteristics of smoothness, heat shrinkability, openability and printability, and an inner layer structure is a micro-foaming layer and has the characteristics of heat shrinkability, air permeability and low density and is used as a core layer of the heat shrinkable film.
The total mass of the outer layer structure accounts for 15%, the total mass of the layer B accounts for 85%, and the outer layer structure material and the inner layer structure material respectively comprise A master batch and B master batch.
The master batch A comprises the following raw materials in parts by weight: 96 parts of polylactic acid (PLA), 0.6 part of NA-305 nucleating agent, 1.2 parts of nano silicon dioxide, 0.7 part of lubricant and 0.5 part of antioxidant.
The master batch B comprises the following raw materials in parts by weight: 80 parts of polylactic acid (PLA), 7 parts of polybutylene succinate (PBS), 8 parts of polybutylene terephthalate-adipate (PBAT), 1.8 parts of a toughening agent, 0.3 part of a chain extender and 0.6 part of an antioxidant.
The processing method of the heat shrinkable film comprises the following steps:
the raw materials A and B are processed into master batches A and B by a double-screw extruder, and the process is shown in Table 4.
And then the A master batch and the B master batch are put into an ABA three-layer co-extrusion casting machine, supercritical carbon dioxide/nitrogen is introduced into a B screw, and a sheet with the thickness of 400 mu m is processed, wherein the process is shown in the table 5.
The processed sheet is placed into a biaxial stretching machine for biaxial stretching, and a light breathable biodegradable heat-shrinkable film with the thickness of 25 mu m can be processed, wherein the light breathable biodegradable heat-shrinkable film has the characteristics of good heat-shrinkable performance, complete biodegradation, low density, high breathability and the like, and the process is shown in Table 6.
TABLE 4
Figure BDA0003826179940000091
TABLE 5
Figure BDA0003826179940000092
TABLE 6
Figure BDA0003826179940000093
Example three:
the biodegradable heat shrinkable film is divided into an ABA three-layer structure shown in figure 1, wherein an outer layer structure has the characteristics of smoothness, heat shrinkability, openability and printability, and an inner layer structure is a micro-foaming layer and has the characteristics of heat shrinkability, air permeability and low density and is used as a core layer of the heat shrinkable film.
The total mass of the outer layer structure accounts for 10-30%, the total mass of the inner layer structure accounts for 70-90%, and the outer layer structure material and the inner layer structure material respectively comprise A master batch and B master batch.
The master batch A comprises the following raw materials in parts by weight: 98 parts of polylactic acid PLA, 1 part of NA-305 nucleating agent, 2 parts of nano silicon dioxide, 1 part of lubricant and 0.8 part of antioxidant.
The master batch B comprises the following raw materials in parts by weight: 70 parts of polylactic acid (PLA), 1 part of polybutylene succinate (PBS), 2 parts of polybutylene terephthalate-adipate (PBAT), 0.5 part of flexibilizer, 0.1 part of chain extender and 0.2 part of antioxidant.
The following is a processing method of the heat shrinkable film:
the raw materials A and B are processed into master batches A and B by a double-screw extruder, and the process is shown in Table 7.
And then putting the master batches A and the master batches B into an ABA three-layer co-extrusion casting machine, introducing supercritical carbon dioxide/nitrogen into a screw B, and processing into a sheet with the thickness of 400 mu m, wherein the process is shown in Table 8.
The processed sheet is placed in a biaxial stretcher for biaxial stretching, and can be processed into a light air-permeable biodegradable heat-shrinkable film with the thickness of 45 mu m, and the light air-permeable biodegradable heat-shrinkable film has the following characteristics of good heat-shrinkable performance, complete biodegradation, low density and high air permeability, and the process is shown in Table 9.
TABLE 7
Figure BDA0003826179940000101
TABLE 8
Figure BDA0003826179940000102
TABLE 9
Figure BDA0003826179940000103
The heat shrinkable film manufactured by the embodiment completely uses full-biodegradable materials, is environment-friendly and has no pollution. Particularly, the density is reduced by a micro-foaming technology, so that the heat shrinkable film has a core layer cellular structure so as to improve the water vapor permeability, and further has excellent characteristics in the aspects of density, water vapor permeability and the like, so that the biodegradable heat shrinkable film disclosed by the invention can be widely used as a substitute for fresh fruit and vegetable packaging bags.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A biodegradable heat shrinkable film is characterized by comprising an outer layer structure consisting of an upper surface layer and a lower surface layer and an inner layer structure consisting of a core layer, wherein the outer layer structure is prepared from the following raw materials: at least one biodegradable polyester, a nucleating agent, nano silicon dioxide and a lubricant; the preparation raw materials of the inner layer structure comprise: polylactic acid, polybutylene succinate, polybutylene terephthalate-adipate, a toughening agent and a chain extender.
2. The biodegradable heat shrinkable film of claim 1, wherein the outer layer is formed in a total mass ratio of 10% to 30% and the inner layer is formed in a total mass ratio of 70% to 90%.
3. A method for preparing a biodegradable heat shrinkable film according to claim 1 or 2, comprising the steps of:
s01: manufacturing A master batch: adding the preparation raw materials of the outer layer structure into a screw extruder to obtain master batches A;
s02: b, manufacturing master batch: adding the preparation raw materials of the inner layer structure into a screw extruder to obtain B master batches;
s03: casting a sheet: putting the A master batch and the B master batch obtained by the processing of the steps S01 and S02 into an ABA three-layer co-extrusion casting machine to finally obtain a sheet consisting of an upper surface layer, a core layer and a lower surface layer, wherein a foaming agent is introduced into a co-extrusion screw rod with the B master batch;
s04: stretching to form a film: and (4) performing biaxial stretching on the sheet processed in the step S03 to obtain the biodegradable heat shrinkable film with high air permeability.
4. The method of claim 3, wherein in the step S01, the preparing raw materials for preparing the A masterbatch further comprise adding an antioxidant to a screw extruder.
5. The method of claim 3, wherein in step S02, the raw material for preparing the B masterbatch further comprises adding an antioxidant into a screw extruder.
6. The method of claim 3, wherein in step S04, the step of stretching to form a film further comprises: heating the sheet processed in the step S03 to 75 ℃ to enable the polymer in the sheet to be in a high-elasticity state; and (4) cooling the stretched sheet material suddenly.
7. The method for preparing a biodegradable heat shrinkable film as claimed in claim 3, wherein in the step S03, the blowing agent is supercritical carbon dioxide or nitrogen.
8. The method of claim 3, wherein in step S03, the pore size of the core layer of the sheet material is 3 μm to 15 μm.
9. The method of claim 4, wherein in the step S01, at least one biodegradable polyester is polylactic acid, the content of the polylactic acid is 95-98 parts, the content of the nucleating agent is 0.3-1 part, the content of the nano-silica is 0.5-2 parts, the content of the lubricant is 0.3-1 part, and the content of the antioxidant is 0.3-0.8 part.
10. The preparation method of the biodegradable heat shrinkable film as claimed in claim 5, wherein in the step S02, the polylactic acid content is 70-90 parts, the polybutylene succinate content is 0-15 parts, the polybutylene terephthalate-adipate content is 0-15 parts, the toughening agent content is 0.5-3 parts, the chain extender content is 0.1-0.5 part, and the antioxidant content is 0.2-1 part.
CN202211061058.8A 2022-08-31 2022-08-31 Biodegradable heat shrinkable film and preparation method thereof Pending CN115416385A (en)

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CN112848422A (en) * 2020-12-30 2021-05-28 江苏光辉包装材料有限公司 Preparation method of biological heat-reducing shrink label film
KR20210095005A (en) * 2020-01-22 2021-07-30 산수음료(주) Biodegradable pla label and film having improved transparency and heat-shrinkable, and method of manufacturing the same
CN113583402A (en) * 2021-09-09 2021-11-02 中化泉州能源科技有限责任公司 Full-biodegradable composite material and preparation method and application thereof
CN114015185A (en) * 2021-10-20 2022-02-08 界首市天鸿新材料股份有限公司 Biodegradable heat shrinkable film and processing technology thereof

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* Cited by examiner, † Cited by third party
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CN103625061A (en) * 2013-11-29 2014-03-12 卫辉市银金达薄膜有限公司 Tape-casting environment-friendly degradable heat-shrink film and manufacturing method thereof
CN106494046A (en) * 2016-10-20 2017-03-15 天津国韵生物材料有限公司 A kind of bio-based heat shrink films that can be degradable
CN108248165A (en) * 2018-01-24 2018-07-06 宜兴市光辉包装材料有限公司 A kind of three-layer co-extruded PVC thermal contractive labels film of core layer foaming and preparation method thereof
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