CN112976744B - Polyethylene composite membrane and preparation method and application thereof - Google Patents

Polyethylene composite membrane and preparation method and application thereof Download PDF

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Publication number
CN112976744B
CN112976744B CN202110345551.1A CN202110345551A CN112976744B CN 112976744 B CN112976744 B CN 112976744B CN 202110345551 A CN202110345551 A CN 202110345551A CN 112976744 B CN112976744 B CN 112976744B
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density polyethylene
polyethylene
composite film
density
low
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CN112976744A (en
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文斌森
魏洪媚
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Jiangmen Hualong Membrane Materials Co ltd
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Jiangmen Hualong Membrane Materials 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
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0017—Combinations of extrusion moulding with other shaping operations combined with blow-moulding or thermoforming
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
    • 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
    • B32B27/08—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 synthetic resin
    • 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
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/327—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polyolefins obtained by a metallocene or single-site catalyst
    • 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
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • 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
    • B32B2250/24—All layers being polymeric
    • B32B2250/242—All polymers belonging to those covered by group B32B27/32
    • 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
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/406—Bright, glossy, shiny surface
    • 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
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/51—Elastic
    • 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
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/558—Impact strength, toughness
    • 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
    • B32B2307/732—Dimensional properties
    • B32B2307/734—Dimensional stability
    • 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
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene
    • 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
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2423/04—Homopolymers or copolymers of ethene
    • C08J2423/06—Polyethene
    • 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
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2423/04—Homopolymers or copolymers of ethene
    • C08J2423/08—Copolymers of ethene

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Laminated Bodies (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

The invention belongs to the technical field of polyethylene materials, and particularly relates to a polyethylene composite film and a preparation method and application thereof. The invention provides a polyethylene composite film, which comprises a surface layer, a middle layer and an inner layer which are bonded in sequence; the surface layer comprises first low-density polyethylene, first high-density polyethylene and a first processing aid; the middle layer comprises second low-density polyethylene, metallocene linear low-density polyethylene, second high-density polyethylene and a second processing aid; the inner layer comprises a third low density polyethylene, a third high density polyethylene and a third processing aid; the thickness of the polyethylene composite film is 40 mu m. Experimental results show that the polyethylene composite film provided by the invention has both thinning and good stiffness.

Description

Polyethylene composite membrane and preparation method and application thereof
Technical Field
The invention belongs to the technical field of polyethylene materials, and particularly relates to a polyethylene composite film and a preparation method and application thereof.
Background
The label film is a self-adhesive label, also called self-adhesive label material, which is a composite material using paper, film or special material as face material, coated with adhesive on its back surface and coated with silicon protective paper as base paper. The Polyethylene (PE) label film is a label film obtained by taking a polyethylene material as a fabric. With the increasingly prominent environmental problems, the reduction of the use of plastic products from the source is crucial to environmental protection, and for PE label films, the reduction of the thickness of PE film fabric in the PE label films can effectively reduce the dosage of PE. However, in the current PE label film, the thickness of the PE composite film is generally more than 70 μm, and the stiffness of the PE composite film is obviously reduced by directly thinning the PE composite film, so that the requirements of printing, gluing and labeling on the stiffness and the flatness of the PE composite film cannot be met.
Disclosure of Invention
In view of the above, the present invention is directed to provide a polyethylene composite film, which has the characteristics of ultra-thin thickness and high stiffness, and further has the advantages of good printing and gluing properties, good die cutting properties, few crystal points, and excellent flatness.
In order to achieve the purpose of the invention, the invention provides the following technical scheme:
the invention provides a polyethylene composite film, which comprises a surface layer, a middle layer and an inner layer which are sequentially bonded;
the surface layer comprises first low-density polyethylene, first high-density polyethylene and a first processing aid; the melt index of the first low-density polyethylene is 1.8-4.0 g/10min, and the density is 0.918-0.935 g/cm 3 (ii) a The melt index of the first high-density polyethylene is 1.0-2.0 g/10min, and the density is 0.950-0.962 g/cm 3 ；
The middle layer comprises second low-density polyethylene, metallocene linear low-density polyethylene, second high-density polyethylene and a second processing aid; the melt index of the second low-density polyethylene is 1.5-2.0 g/10min, and the density is 0.920-0.935 g/cm 3 (ii) a The melt index of the metallocene linear low density polyethylene is 0.8 to 2.0g/10min, and the density is 0.915 to 0.920g/cm 3 (ii) a The melt index of the second high-density polyethylene is 0.5 to 2.0g/10min, and the density is 0.950 to 0.962g/cm 3 ；
The inner layer comprises a third low density polyethylene, a third high density polyethylene and a third processing aid; the melt index of the third low-density polyethylene is 1.8-4.0 g/10min, and the density is 0.918-0.935 g/cm 3 (ii) a The melt index of the third high-density polyethylene is 1.0-2.0 g/10min, and the density is 0.950-0.962 g/cm 3 ；
The thickness of the polyethylene composite film is 30-40 mu m.
Preferably, the mass ratio of the surface layer, the middle layer and the inner layer is (10-35): (30-80): (10 to 35).
Preferably, the surface layer comprises the following components in percentage by mass: 40-80% of first low-density polyethylene, 15-60% of first high-density polyethylene and 0.5-1.5% of first processing aid, wherein the mass percentage of all components of the surface layer is 100%.
Preferably, the middle layer comprises the following components in percentage by mass: 30-70% of second low-density polyethylene, 5-20% of metallocene linear low-density polyethylene, 25-70% of second high-density polyethylene and 0.5-1.5% of second processing aid, wherein the mass percentage of each component of the middle layer is 100%.
Preferably, the inner layer comprises the following components in percentage by mass: 40-85% of third low-density polyethylene, 15-60% of third high-density polyethylene and 0.5-1.5% of third processing aid, wherein the mass percentages of the components of the inner layer are 100%.
Preferably, the middle layer further comprises a milky white color master batch.
The invention also provides a preparation method of the polyethylene composite membrane in the technical scheme, which comprises the following steps:
co-extruding blown films by adopting a three-layer blown film co-extrusion method after melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer to obtain a primary composite film;
and sequentially carrying out longitudinal stretching and corona treatment on the primary composite film to obtain the polyethylene composite film.
Preferably, the ratio of the longitudinal stretching is 3 to 5.
Preferably, the output power of the corona treatment is 3.5 kW-5 kW.
The invention also provides application of the polyethylene composite film or the polyethylene composite film prepared by the preparation method in the technical scheme as label film fabric.
The invention provides a polyethylene composite film, which comprises a surface layer, a middle layer and an inner layer which are sequentially bonded; the surface layer comprises first low-density polyethylene, first high-density polyethylene and a first processing aid; the melt index of the first low-density polyethylene is 1.8-4.0 g/10min, and the density is 0.918-0.935 g/cm 3 (ii) a The melt index of the first high-density polyethylene is 1.0-2.0 g/10min, and the density is 0.950-0.962 g/cm 3 (ii) a The middle layer comprises second low-density polyethylene, metallocene linear low-density polyethylene, second high-density polyethylene and a second processing aid; the melt index of the second low-density polyethylene is 1.5-2.0 g/10min, and the density is 0.920-0.935 g/cm 3 (ii) a Process for preparing metallocene linear low density polyethyleneThe melt index is 0.8-2.0 g/10min, and the density is 0.915-0.920 g/cm 3 (ii) a The melt index of the second high-density polyethylene is 0.5-2.0 g/10min, and the density is 0.950-0.962 g/cm 3 (ii) a The inner layer comprises a third low density polyethylene, a third high density polyethylene and a third processing aid; the melt index of the third low-density polyethylene is 1.8-4.0 g/10min, and the density is 0.918-0.935 g/cm 3 (ii) a The melt index of the third high-density polyethylene is 1.0-2.0 g/10min, and the density is 0.950-0.962 g/cm 3 (ii) a The thickness of the polyethylene composite film is 40 mu m.
In the invention, the polyethylene compositions of the surface layer and the inner layer are similar or identical, which is beneficial to avoiding the curling of the polyethylene composite layer and ensuring the gluing and surface printing performances of the polyethylene composite film; the metallocene linear low density polyethylene in the middle layer has high toughness, which is beneficial to improving the tensile property of the polyethylene composite film and further beneficial to thinning the polyethylene composite film; according to the invention, the mechanical property and stiffness of the middle layer are improved by matching polyethylene with metallocene linear low-density polyethylene in different densities in the middle layer, and meanwhile, the polyethylene in the surface layer and the polyethylene in the inner layer are cooperatively matched, so that the dimensional stability of the polyethylene composite film is jointly ensured, the ultra-thin thickness index is favorably reached while the stiffness of the polyethylene composite film is ensured, and in addition, the crystal points of the polyethylene composite film are favorably reduced, the glossiness and the flatness of the polyethylene composite film are improved, and the die cutting performance is favorably improved.
Experimental results show that the polyethylene composite film provided by the invention has the advantages that the longitudinal tensile strength is 164-196 MPa, the transverse tensile strength is 20.6-25.6 MPa, the longitudinal elongation at break is 90-112%, the transverse elongation at break is 705-780%, and the tensile property is excellent; the longitudinal elastic modulus is 775-860 MPa, the transverse elastic modulus is 778-856 MPa, the elastic modulus is high, and the stiffness is high; the glossiness is 95-115%, and the glossiness is high. The polyethylene composite film provided by the invention has the advantages of thinning and good stiffness of the polyethylene composite film.
Detailed Description
The invention provides a polyethylene composite film, which comprises a surface layer, a middle layer and an inner layer which are sequentially bonded;
the surface layer comprises first low-density polyethylene, first high-density polyethylene and a first processing aid;
the middle layer comprises second low-density polyethylene, metallocene linear low-density polyethylene, second high-density polyethylene and a second processing aid;
the inner layer comprises a third low density polyethylene, a third high density polyethylene and a third processing aid;
the thickness of the polyethylene composite film is 30-40 μm.
In the present invention, the components of the polyethylene composite film are commercially available products well known to those skilled in the art, unless otherwise specified.
In the invention, the polyethylene composite film comprises a surface layer, and the surface layer comprises first low-density polyethylene, first high-density polyethylene and a first processing aid.
The skin layer of the present invention preferably comprises 40 to 80% by mass of the first low density polyethylene, more preferably 45 to 75% by mass of the skin layer. In the invention, the melt index of the first low-density polyethylene is 1.8-4.0 g/10min, preferably 2.0-3.5 g/10min; the density is 0.918-0.935 g/cm 3 Preferably 0.920 to 0.930g/cm 3 . In an embodiment of the invention, the first low density polyethylene is preferably Shell's 2420H, melt index is 2.0g/10min, density is 0.924g/cm 3 Or preferably 582E available from Dow chemical, with a melt index of 3.5g/10min and a density of 0.923g/cm 3 . In the invention, the first low-density polyethylene has the characteristics of less crystal points, high cleanliness, high glossiness and low elongation at break, and is beneficial to the subsequent die cutting process of the polyethylene composite film, so that the polyethylene composite film has less crystal points and is easy to process.
The skin layer of the present invention preferably comprises 15 to 60% by mass of the first high density polyethylene, more preferably 20 to 55% by mass of the skin layer. In the invention, the melt index of the first high-density polyethylene is 1.0-2.0 g/10min, preferably 1.2-1.8 g/10min; the density is 0.950-0.962 g/cm 3 Preferably 0.951 to 0.961g/cm 3 . In an embodiment of the invention, the first high density polyethylene is preferably Thailand energyHD3355 from Source and petrochemical company (Thailand PTT company), melt index 1.1g/10min, density 0.951g/cm 3 Or preferably M6012EP available from Darlian petrochemical, inc., mitsuga, 1.2g/10min, and 0.960g/cm 3 . In the invention, the second low-density polyethylene has good glossiness, can provide higher stiffness for the polyethylene composite film, keeps the dimensional stability of the polyethylene composite film, and provides enough tensile strength for the subsequent die-cutting process, so that the polyethylene composite film has the characteristics of high crystal point and stiffness.
The surface layer of the present invention preferably includes 0.5 to 1.5% by mass of the first processing aid, more preferably 0.6 to 1.4% by mass of the surface layer. In the invention, the first processing aid is preferably PA0801LD of Suzhou Constantam engineering plastics, inc., with a melt index of 3.5g/10min and a density of 0.920g/cm 3 The content of the effective component is 5wt.%. In the invention, the first processing aid is beneficial to lubricating a flow channel of an extruder and a die head, the melt fracture condition of the polyethylene composite film is reduced, and the smoothness and the brightness of the film surface of the polyethylene composite film are improved.
In the present invention, the mass percentages of the components of the surface layer are 100%.
In the invention, the polyethylene composite film comprises a middle layer, and the middle layer comprises second low-density polyethylene, metallocene linear low-density polyethylene, second high-density polyethylene and a second processing aid.
The middle layer of the present invention preferably includes 30 to 70% by mass of the second low density polyethylene, more preferably 35 to 65% by mass of the middle layer. In the invention, the melt index of the second low-density polyethylene is 1.5-2.0 g/10min, preferably 1.6-2.0 g/10min; the density is 0.920 to 0.935g/cm 3 Preferably 0.922 to 0.933g/cm 3 . In an embodiment of the invention, the second low density polyethylene is preferably 450E available from Dow chemical company, with a melt index of 2.0g/10min and a density of 0.924g/cm 3 Or preferably 151BW ex Exxon Mobil, 2.0g/10min melt index and 0.933g/cm density 3 . In the present invention, the second low-density polyethyleneThe alkene has the characteristics of few crystal points, high cleanliness, high glossiness and low elongation at break, and is beneficial to the subsequent die cutting process of the polyethylene composite membrane, so that the polyethylene composite membrane has few crystal points and is easy to process.
The middle layer of the present invention preferably comprises 5 to 20% by mass of the metallocene linear low density polyethylene, more preferably 7 to 18% by mass of the middle layer. In the invention, the melt index of the metallocene linear low density polyethylene is 0.8-2.0 g/10min, preferably 1.0-1.8 g/10min; the density is 0.915-0.920 g/cm 3 Preferably 0.915 to 0.918g/cm 3 . In the examples of the present invention, the metallocene linear low density polyethylene is preferably XP8318 from Exxon Mobil, having a melt index of 1.0g/10min and a density of 0.918g/cm 3 Or preferably 8115 from Sauter basic industries, inc., melt index of 1.1g/10min, density of 0.915g/cm 3 . In the invention, the metallocene linear low-density polyethylene has higher toughness, is beneficial to improving the tensile property and ductility of the polyethylene composite film, and effectively prevents the occurrence of stretch breaking of the polyethylene composite film.
The middle layer of the present invention preferably includes 25 to 70% by mass of the second high density polyethylene, more preferably 30 to 65% by mass of the middle layer. In the invention, the melt index of the second high-density polyethylene is 0.5-2.0 g/10min, preferably 0.7-2.0 g/10min; the density is 0.950-0.962 g/cm 3 Preferably 0.952 to 0.961g/cm 3 . In an embodiment of the present invention, the second high density polyethylene is preferably 5960 available from Dow chemical company, with a melt index of 0.7g/10min and a density of 0.961g/cm 3 Or preferably H555JA of Siamese chemical industry limited company (SCG) in Thailand, the melt index is 1.8g/10min, and the density is 0.954g/cm 3 . In the invention, the second high-density polyethylene has lower crystal point and higher stiffness, which is beneficial to maintaining the dimensional stability of the polyethylene composite film, providing enough tensile strength for the subsequent die-cutting process and ensuring that the polyethylene composite film has fewer crystal points and high stiffness.
The middle layer preferably comprises 0.5 to 1.5 percent of second processing aid in percentage by mass of the middle layer, and more preferably comprises 0.5 to 1.5 percent of second processing aid in percentage by mass of the middle layer0.6 to 1.4 percent is selected. In the present invention, the second processing aid is preferably PA0801LD, suzhou Constantam engineering plastics Co., ltd, with a melt index of 3.5g/10min and a density of 0.920g/cm 3 The content of the effective component is 5wt.%. In the invention, the second processing aid is beneficial to lubricating a flow passage of the extruder and the die head, reducing the melt fracture condition of the polyethylene composite film and improving the smoothness and the brightness of the film surface of the polyethylene composite film.
In the present invention, the intermediate layer preferably further includes a milky white color master batch. The middle layer preferably comprises 15-20% of milky white master batch by mass percent of the middle layer, and more preferably 16-19% of milky white master batch by mass percent of the middle layer. In the invention, the melt index of the milky white color master batch is preferably 5-15 g/10min, and more preferably 8-15 g/10min; the density is preferably 1.8 to 2.2g/cm 3 More preferably 1.9 to 2.1g/cm 3 . In the embodiment of the invention, the milky white master batch is preferably 8000CN of Schelman plastics, the melt index is 11.5g/10min, and the density is 2.0g/cm 3 The titanium dioxide content is 70wt.%, or preferably XP140026 from Guangdong American Union New materials GmbH, the melt index is 15g/10min, and the density is 2.1g/cm 3 Titanium dioxide content was 72wt.%. In the invention, the milky white color master batch has good dispersibility and covering power, has the characteristics of aging resistance and yellowing resistance, and is beneficial to improving the aging resistance of the polyethylene composite film. In the invention, the polyethylene composite film without the addition of the milky white master batch is transparent; the polyethylene composite film added with the milky color master batch is milky white.
In the invention, the mass percentage of each component of the middle layer is 100 percent.
In the present invention, the polyethylene composite film includes an inner layer including a third low density polyethylene, a third high density polyethylene, and a third processing aid.
The inner layer of the present invention preferably comprises 40 to 85% of the third low density polyethylene, more preferably 45 to 80% by mass of the inner layer. In the invention, the melt index of the third low-density polyethylene is 1.8-4.0 g/10min, preferably 2.0-3.5 g/10min; the density is 0.918-0.935 g/cm 3 Preferably 0.920 to 0.930g/cm 3 . In an embodiment of the invention, the third low density polyethylene is preferably Shell's 2420H, melt index is 2.0g/10min, density is 0.924g/cm 3 Or preferably 582E available from Dow chemical, with a melt index of 3.5g/10min and a density of 0.923g/cm 3 . In the invention, the third low-density polyethylene has the characteristics of less crystal points, high cleanliness, high glossiness and low elongation at break, and is beneficial to the subsequent die cutting process of the polyethylene composite film, so that the polyethylene composite film has less crystal points and is easy to process.
The inner layer of the present invention preferably includes 15 to 60% of the third high density polyethylene, more preferably 20 to 55% by mass of the inner layer. In the invention, the melt index of the third high-density polyethylene is 1.0-2.0 g/10min, preferably 1.2-1.8 g/10min; the density is 0.950-0.962 g/cm 3 Preferably 0.951 to 0.961g/cm 3 . In an embodiment of the present invention, the third high density polyethylene is preferably HD3355 from Thailand energy and petrochemical company (Thailand PTT company), with a melt index of 1.1g/10min and a density of 0.951g/cm 3 Or preferably M6012EP available from Darlian petrochemical, inc., mitsuga, 1.2g/10min, and 0.960g/cm 3 . In the invention, the third low-density polyethylene has good glossiness, can provide higher stiffness for the polyethylene composite film, keeps the dimensional stability of the polyethylene composite film, and provides enough tensile strength for the subsequent die-cutting process, so that the polyethylene composite film has the characteristics of high crystal point and stiffness.
The inner layer of the present invention preferably includes 0.5 to 1.5% of the third processing aid, more preferably 0.6 to 1.4% by mass of the inner layer. In the invention, the third processing aid is PA0801LD from engineering plastics of Suzhou Constanto, inc., with a melt index of 3.5g/10min and a density of 0.920g/cm 3 The content of the effective component is 5wt.%. In the invention, the third processing aid is beneficial to lubricating runners of the extruder and the die head, reducing the melt fracture condition of the polyethylene composite film and improving the smoothness and the brightness of the film surface of the polyethylene composite film.
In the present invention, the total mass percentage of the components of the inner layer is 100%.
In the present invention, the thickness of the polyethylene composite film is 30 to 40 μm, preferably 32 to 40 μm, and more preferably 34 to 40 μm.
In the present invention, the mass ratio of the surface layer, the middle layer and the inner layer is preferably (10 to 35): (30-80): (10 to 35), more preferably (12 to 33): (35-75): (12 to 32), more preferably (15 to 30): (40 to 70): (15 to 30), specifically, 1:2: 1. 3:4: 3. 1:3:1 or 1:4:1.
the invention also provides a preparation method of the polyethylene composite membrane in the technical scheme, which comprises the following steps:
co-extruding blown films by adopting a three-layer blown film co-extrusion method after melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer to obtain a primary composite film;
and sequentially carrying out longitudinal stretching and corona treatment on the primary composite film to obtain the polyethylene composite film.
In the present invention, the components in the preparation method are the same as those of the polyethylene composite film in the above technical scheme, and are not described herein again.
The method co-extrudes blown films by adopting a three-layer blown film co-extrusion method after melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer to obtain the primary composite film.
The raw materials of the surface layer, the middle layer and the inner layer are respectively blended and then respectively conveyed to feed inlets of the surface layer, the middle layer and the inner layer of an extruder through vacuum negative pressure, and the raw materials of the surface layer, the middle layer and the inner layer are respectively subjected to melting plasticization and then are filtered and then are sent to a die head for coextrusion film blowing to obtain the primary composite film. In the present invention, the filtration device is preferably a filter. In the present invention, the filtration preferably comprises a screen; according to the sequence of the raw materials, the mesh number of the screen is preferably 60 meshes, 80 meshes, 200 meshes and 60 meshes in sequence. In the present invention, the extrusion blown film is preferably a three-layer blown film co-extrusion process. The blowing process is not particularly limited, and a blowing process known to those skilled in the art may be used. In the present invention, the temperature of the die in the blown film is preferably 185 to 196 ℃. In the invention, in the extrusion of the surface layer, the temperature of an extruder is preferably 165-185 ℃, and the extrusion pressure is preferably 280-365 bar; in the middle layer extrusion, the temperature of an extruder is preferably 172-182 ℃, and the extrusion pressure is preferably 265-325 bar; in the extrusion of the inner layer, the temperature of the extruder is preferably 165 to 187 ℃, and the extrusion pressure is preferably 280 to 365bar. In the present invention, the extrusion rate of the extruder is selected from 350 to 380kg/h, more preferably 355 to 375kg/h.
In the present invention, the thickness of the primary composite film is preferably 100 to 160 μm, more preferably 110 to 150 μm, and still more preferably 120 to 140 μm.
After the primary composite film is obtained, the primary composite film is sequentially subjected to longitudinal stretching and corona treatment to obtain the polyethylene composite film.
Before the longitudinal stretching, the invention preferably further comprises precooling, barrel film flattening and cooling the primary composite film in sequence. In the invention, the pre-cooling is preferably air-cooling; the cooling air in the air cooling is preferably an automatic air ring. In the present invention, the temperature of the automatic air ring is preferably 10 to 25 ℃, more preferably 15 to 20 ℃. In the invention, the process of flattening the drum membrane is preferably that the primary composite membrane enters a stable ring and a stable membrane bubble, then enters a herringbone plate and bubbles, is clamped into a flat drum membrane, and then enters an upper traction rotating device.
In the embodiment of the present invention, the cooling device is preferably a cooling roller, specifically, 8 cooling rollers with a diameter of 120-200 mm are used for cooling after the film is flattened. In the present invention, the temperature of the cooling roll is independently preferably 35 to 45 ℃. According to the sequence of the film passing through the cooling rollers, the temperature of the cooling rollers is consistent or reduced in a gradient manner. In the invention, the cooling guide rollers are connected in series.
In the present invention, the ratio of the longitudinal stretching is preferably 3 to 5 times, more preferably 3 to 4 times, and still more preferably 3 to 3.5 times. In the present invention, the longitudinal drawing includes preheating, drawing, annealing, and cooling in this order.
In an embodiment of the invention, the preheated equipment is preferably a stretcher. In the present invention, the preheating is preferably effected by means of a preheating roll. In the present invention, the number of the preheating rolls is preferably 4, and the diameter of the preheating rolls is preferably 240mm. In the present invention, the temperature of the preheating roll is preferably 55 to 85 ℃; according to the sequence of the primary composite film passing through the preheating rollers, the temperature of the two front preheating rollers is more preferably 55-65 ℃, and the temperature of the two rear preheating rollers is 70-85 ℃. In the invention, the temperature of the preheating rollers is consistent or increased in steps according to the sequence of the film passing through the preheating rollers.
In the present invention, the stretching apparatus is preferably a stretcher. In the present invention, the stretching is preferably effected by stretching rollers; the number of the drawing rolls is preferably 2, and the diameter of the drawing rolls is preferably 240mm. The invention does not specially limit the stretching multiple of a single stretching roller in the stretching roller so as to ensure the integral longitudinal stretching multiple. In the present invention, the stretching rollers are connected in series. In the present invention, the temperature of the stretching roll is independently preferably 95 to 108 ℃. In the invention, the stretching speed and the traction speed of the film blowing machine are synchronous in the stretching process.
After longitudinal unidirectional stretching, the invention anneals the obtained longitudinal stretching composite film. In the present invention, the annealing is preferably performed by an annealing roller. In the present invention, the number of the annealing rollers is preferably 2. In the invention, the annealing rollers are connected in series. In the present invention, the temperature of the annealing roller is independently preferably 102 to 115 ℃.
After annealing, the present invention preferably subjects the obtained annealed product to a cooling treatment. In the present invention, the cooling treatment after the annealing is preferably performed by a cooling roll. In the present invention, the number of the cooling rolls is preferably 2. In the present invention, the cooling rolls are connected in series. According to the sequence of the films obtained after annealing, the temperature of the first 1 cooling roller in the cooling rollers is preferably 62-70 ℃, and the temperature of the second 1 cooling roller is preferably 33-45 ℃. The invention releases the internal stress of the film again through the cooling treatment after the annealing, so that the composite film is completely flattened.
After cooling treatment, the cooling treatment product is subjected to corona treatment, and the output power of the corona treatment is 3kW to 5kW, and more preferably 3.5kW to 4.5kW.
The invention also provides application of the polyethylene composite film in the technical scheme or the polyethylene composite film prepared by the preparation method in the technical scheme as a label film fabric.
In order to further illustrate the present invention, the following examples are provided to describe the polyethylene composite film and the preparation method and application thereof in detail, but they should not be construed as limiting the scope of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The reagents used in the examples are all commercially available.
Example 1
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer and the inner layer is 3:4:3; the surface layer comprises 79 percent of low-density polyethylene 2420H, 20 percent of high-density polyethylene HD3355 and 1 percent of PA0801LD in percentage by mass; the middle layer comprises 35% of low density polyethylene 2420H, 12% of metallocene linear low density polyethylene, 52% of high density polyethylene H555JA and 1% of PA0801LD in percentage by mass; the inner layer comprises 79% of low-density polyethylene 2420H, 20% of high-density polyethylene HD3355 and 1% of PA0801LD in percentage by mass.
The preparation method comprises the following steps:
respectively mixing the raw materials of the surface layer, the middle layer and the inner layer in proportion by an automatic batching system, then respectively sending the mixture into surface layer, middle layer and inner layer extruders, sequentially melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer, filtering the mixture by a filter, and then sending the mixture into a die head, wherein the temperature of the die head is 185-195 ℃, the thickness of the die head is adjusted to 120 mu m, and the extrusion blow molding is carried out, wherein the temperature of the surface layer extruder is 170-185 ℃, and the extrusion pressure is 280-340 bar; the temperature of the extruder in the middle layer is 172-182 ℃, and the extrusion pressure is 265-325 bar; the temperature of the extruder of the inner layer is 170-185 ℃, the extrusion pressure is 280-340 bar, the extrusion speed is 360kg/h, and the specific extrusion parameters of the primary composite film are shown in table 1, so as to obtain the primary composite film;
cooling the obtained primary composite film by an automatic air ring, then stabilizing the film bubble by a stabilizing ring, soaking by a herringbone plate, clamping the film bubble of the primary composite film into a flat cylindrical film, entering an upper traction optional device, flattening the film, sequentially entering 8 serially-connected cooling rollers with the diameter of 120-200 mm for further cooling, sequentially entering 4 serially-connected preheating rollers with the diameter of 240mm, sequentially entering 2 preheating rollers with the temperature of 55-65 ℃ and 2 preheating rollers with the temperature of 70-85 ℃ according to the sequence of passing the film, wherein the temperature of the preheating rollers is increased in steps, then entering 2 stretching rollers with the diameter of 240mm and the temperature of 95-108 ℃ respectively, the stretching speed is synchronous with the traction speed of a film blowing machine, the stretching ratio is 3 times, then entering 2 serially-connected annealing rollers with the temperature of 102-115 ℃, annealing, then entering 2 cooling rollers (sequentially passing the film, the temperature of the first 1 cooling roller in the cooling rollers is 62-70 ℃, and the temperature of the second cooling roller is preferably 33-45 ℃) completely cooling the film; then the mixture enters a corona treatment device to carry out corona treatment under the condition that the output power is 3.8kW, and the polyethylene composite film with the thickness of 40 mu m is obtained.
TABLE 1 Primary composite film specific extrusion parameters
Figure BDA0003000581570000111
Example 2
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer, and the inner layer is 1:2:1, the other technical means are the same as the embodiment 1, and the polyethylene composite film with the thickness of 40 μm is obtained.
Example 3
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer and the inner layer is 1:3:1; the surface layer comprises 69.5 percent of low-density polyethylene 2420H, 30 percent of high-density polyethylene HD3355 and 0.5 percent of PA0801LD by mass percentage; the middle layer comprises 31.2 percent of low density polyethylene 2420H, 24 percent of metallocene linear low density polyethylene, 44 percent of high density polyethylene H555JA and 0.8 percent of PA0801LD in percentage by mass; the inner layer comprises 69.5% by mass of low density polyethylene 2420H, 30% by mass of high density polyethylene HD3355 and 0.5% by mass of PA0801LD.
The preparation method comprises the following steps:
respectively mixing the raw materials of the surface layer, the middle layer and the inner layer in proportion by an automatic batching system, then respectively sending the mixture into surface layer, middle layer and inner layer extruders, sequentially melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer, filtering the mixture by a filter, and then sending the mixture into a die head, wherein the temperature of the die head is 185-196 ℃, the thickness of the die head is adjusted to be 128 mu m, and the extrusion blow molding is carried out, wherein the temperature of the surface layer extruder is 175-187 ℃, and the extrusion pressure is 293-365 bar; the temperature of the extruder in the middle layer is 172-182 ℃, and the extrusion pressure is 265-325 bar; the temperature of the extruder of the inner layer is 175-187 ℃, the extrusion pressure is 293-365 bar, the extrusion speed is 365kg/h, and the specific extrusion parameters of the primary composite film are shown in table 2, so that the primary composite film is obtained;
cooling the obtained primary composite film by an automatic air ring, then stabilizing the film bubble by a stabilizing ring, bubble soaking by a herringbone plate, clamping the film bubble of the primary composite film into a flat cylindrical film, entering an upper traction optional device, flattening the film, sequentially entering 8 serially connected cooling rollers with the diameter of 120-200 mm for further cooling, sequentially entering 4 serially connected preheating rollers with the diameter of 240mm, sequentially entering 2 preheating rollers with the temperature of 55-65 ℃ and 2 preheating rollers with the temperature of 70-85 ℃ according to the sequence of passing the film, gradually increasing the temperature of the preheating rollers, then entering 2 stretching rollers with the diameter of 240mm and the temperature of 95-108 ℃ respectively, synchronizing the stretching speed with the traction speed of a film blowing machine, enabling the stretching multiple to be 3.2 times, then entering 2 serially connected annealing rollers with the temperature of 102-115 ℃, and then entering 2 cooling rollers (sequentially entering the sequence of passing the film obtained after annealing, enabling the temperature of the first 1 cooling roller to be 62-70 ℃, and preferably completely cooling the obtained film after cooling by cooling rollers at the temperature of 45-45 ℃); then the mixture enters a corona treatment device to carry out corona treatment under the condition that the output power is 4kW, and the polyethylene composite film with the thickness of 40 mu m is obtained.
TABLE 2 Primary composite film specific extrusion parameters
Figure BDA0003000581570000121
Example 4
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer, and the inner layer is 22.5:55:22.5, the other technical means are the same as the embodiment 3, and the polyethylene composite membrane with the thickness of 40 μm is obtained.
Example 5
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer and the inner layer is 1:2:1; the surface layer comprises 76.2 percent of low-density polyethylene 582E, 23 percent of high-density polyethylene HD3355 and 0.8 percent of PA0801LD by mass percentage; the middle layer comprises 35.3 percent of low density polyethylene 2420H, 15 percent of metallocene linear low density polyethylene, 49 percent of high density polyethylene H555JA and 0.7 percent of PA0801LD according to mass percentage; the inner layer comprises 76.2% by mass of low density polyethylene 582E, 23% by mass of high density polyethylene HD3355 and 0.8% by mass of PA0801LD.
The preparation method comprises the following steps:
respectively mixing the raw materials of the surface layer, the middle layer and the inner layer in proportion through an automatic material mixing system, respectively sending the mixture into surface layer, middle layer and inner layer extruders, sequentially melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer, filtering the mixture through a filter, sending the mixture into a die head, adjusting the temperature of the die head to be 185-195 ℃, adjusting the thickness to be 152 mu m, extruding and blowing a film, wherein the temperature of the surface layer extruder is 165-178 ℃, and the extrusion pressure is 280-340 bar; the temperature of the extruder in the middle layer is 172-182 ℃, and the extrusion pressure is 265-325 bar; the temperature of an extruder of the inner layer is 165-178 ℃, the extrusion pressure is 280-340 bar, the extrusion speed is 370kg/h, and the specific extrusion parameters of the primary composite film are shown in table 3 to obtain the primary composite film;
cooling the obtained primary composite film by an automatic air ring, then cooling the primary composite film by a stable ring stable film bubble and a herringbone plate, clamping the primary composite film bubble into a flat cylindrical film, entering an upper traction optional device, flattening the film, sequentially entering 8 serially-connected cooling rollers with the diameter of 120-200 mm for further cooling, entering the cooled film into a stretcher for heating and stretching, sequentially entering 4 serially-connected preheating rollers with the diameter of 240mm, sequentially passing the films, leading 2 preheating rollers with the temperature of 55-65 ℃ and the following 2 preheating rollers with the temperature of 70-85 ℃ according to the sequence of passing the films, leading the preheating rollers to have the temperature of gradient rise, then entering 2 stretching rollers with the diameter of 240mm and the temperature of 95-108 ℃ respectively, synchronizing the stretching speed with the traction speed of a film blowing machine, leading the stretching times to be 3.8 times, then entering 2 serially-connected annealing rollers with the temperature of 102-115 ℃ after stretching, and then entering 2 cooling rollers (sequentially passing the first 1-70 ℃ of the cooling rollers after annealing, and preferably cooling rollers with the temperature of 45-45 ℃ after completely cooling the films after annealing; then the mixture enters a corona treatment device to carry out corona treatment under the condition that the output power is 4.2kW, and the polyethylene composite film with the thickness of 40 mu m is obtained.
TABLE 3 Primary composite film specific extrusion parameters
Figure BDA0003000581570000131
Example 6
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer and the inner layer is 1:2:1; the surface layer comprises 74.2 percent by mass of low-density polyethylene 582E, 25 percent by mass of high-density polyethylene M6012EP and 0.8 percent by mass of PA0801LD; the middle layer comprises 46.2 percent of low density polyethylene 2420H, 10 percent of metallocene linear low density polyethylene, 43 percent of high density polyethylene H555JA and 0.8 percent of PA0801LD in percentage by mass; the inner layer comprises 74.2% by mass of low density polyethylene 2420H, 25% by mass of high density polyethylene M6012EP and 0.8% by mass of PA0801LD.
The preparation method was the same as in example 5, and a polyethylene composite film having a thickness of 40 μm was obtained.
Comparative example 1
In the polyethylene composite film prepared by the comparative example, the low-density polyethylene is FD0270 of Catal petrochemical Co., ltd, the melt index is 2.4g/10min, and the density is 0.923g/cm 3 (ii) a The high density polyethylene comprises 81841.27 from Dow chemical company, melt index of 6.0g/10min, and density of 0.9470.923g/cm 3 (ii) a The high density polyethylene comprises HTA108 from Exxon Mobil, with a melt index of 0.7g/10min and a density of 0.961g/cm 3 (ii) a The processing aid is PEA-3S of the Huayi scientific and technological development limited company, the melt index is 2g/10min, and the density is 0.94g/cm 3 The content of the effective component is 3wt.%.
In the polyethylene composite film prepared by the comparative example, the mass ratio of the surface layer, the middle layer and the inner layer is 1:2:1; the surface layer comprises, by mass, 74% of low density polyethylene FD0270, 25% of high density polyethylene 81841.27, and 1% of PEA-3S; the middle layer comprises, by mass, 45% of low density polyethylene FD0270, 54% of high density polyethylene HTA108 and 1% of PEA-3S; the inner layer comprises 74 percent of low density polyethylene FD0270, 25 percent of high density polyethylene 81841.27 and 1 percent of PEA-3S in percentage by mass.
The preparation method comprises the following steps:
respectively mixing the raw materials of the surface layer, the middle layer and the inner layer in proportion by an automatic batching system, then respectively sending the mixture into surface layer, middle layer and inner layer extruders, sequentially melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer, filtering the mixture by a filter, and then sending the mixture into a die head, wherein the temperature of the die head is 185-196 ℃, the thickness of the die head is adjusted to be 80 mu m, and the extrusion blow molding is carried out, wherein the temperature of the surface layer extruder is 175-187 ℃, and the extrusion pressure is 293-365 bar; the temperature of the middle layer extruder is 172-182 ℃, and the extrusion pressure is 265-325 bar; the temperature of an extruder of the inner layer is 175-187 ℃, the extrusion pressure is 293-365 bar, the extrusion rate is 330kg/h, and the specific extrusion parameters of the primary composite film are shown in table 4 to obtain the primary composite film;
cooling the obtained primary composite film by an automatic air ring, then stabilizing the film bubble by a stabilizing ring, soaking by a herringbone plate, clamping the film bubble of the primary composite film into a flat cylindrical film, entering an upper traction optional installation device, flattening the film, sequentially entering 8 cooling rollers which are connected in series and have the diameter of 120-200 mm for further cooling, entering a corona treatment device for the cooled film, and carrying out corona treatment under the condition that the output power is 3.5kW to obtain the polyethylene composite film with the thickness of 80 mu m.
TABLE 4 Primary composite film specific extrusion parameters
Figure BDA0003000581570000151
The polyethylene composite films obtained in examples 1 to 6 and comparative example 1 were respectively tested for tensile strength and elongation at break according to GB/T1040.3 to 2006, the polyethylene composite films obtained in examples 1 to 6 and comparative example 1 were respectively tested for elastic modulus according to ASTM D882, the polyethylene composite films obtained in examples 1 to 6 and comparative example 1 were respectively tested for haze according to GB/T2410 to 2008, and the polyethylene composite films obtained in examples 1 to 6 and comparative example 1 were respectively tested for gloss according to GB/T8807 to 1988, the test results of which are shown in Table 5.
TABLE 5 results of testing the Properties of the polyethylene composite films obtained in examples 1 to 6 and comparative example 1
Figure BDA0003000581570000152
As can be seen from Table 5, the polyethylene composite film provided by the invention has the longitudinal tensile strength of 173-196 MPa, the transverse tensile strength of 23.7-25.6 MPa and the longitudinal elongation at break of 92-112%, and is not easy to cause printing deformation due to stretching; the transverse breaking elongation is 760-780%, and the tensile property is excellent; the longitudinal elastic modulus is 780-860 MPa, the transverse elastic modulus is 780-856 MPa, the elastic modulus is high, and the stiffness is high; the haze is 4.1-4.6%, the glossiness is 95-115%, and the glossiness is high.
Example 7
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer, and the inner layer is 3:4:3; the surface layer comprises 79 percent of low-density polyethylene 2420H, 20 percent of high-density polyethylene HD3355 and 1 percent of PA0801LD in percentage by mass; the middle layer comprises 27% of low density polyethylene 2420H, 12% of metallocene linear low density polyethylene, 41.5% of high density polyethylene H555JA, 18.5% of milky white master batch 8000CN and 1% of PA0801LD by mass percentage; the inner layer comprises 79% of low-density polyethylene 2420H, 20% of high-density polyethylene HD3355 and 1% of PA0801LD in percentage by mass.
The preparation method was the same as in example 1, and a polyethylene composite film having a thickness of 40 μm was obtained.
Example 8
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer, and the inner layer is 1:2:1, the other technical means are the same as the embodiment 7, and the polyethylene composite film with the thickness of 40 μm is obtained.
Example 9
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer and the inner layer is 1:3:1; the surface layer comprises 69.5 percent of low-density polyethylene 2420H, 30 percent of high-density polyethylene HD3355 and 0.5 percent of PA0801LD by mass percentage; the middle layer comprises 31.2 percent of low density polyethylene 2420H, 10 percent of metallocene linear low density polyethylene, 40 percent of high density polyethylene H555JA, 18 percent of milky white master batch 8000CN and 0.8 percent of PA0801LD according to mass percentage; the inner layer comprises 69.5% by mass of low density polyethylene 2420H, 30% by mass of high density polyethylene HD3355 and 0.5% by mass of PA0801LD.
The preparation method was the same as in example 3, and a polyethylene composite film having a thickness of 40 μm was obtained.
Example 10
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer, and the inner layer is 22.5:55:22.5, the rest technical means are the same as the embodiment 9, and the polyethylene composite membrane with the thickness of 40 μm is obtained.
Example 11
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer, and the inner layer is 1:2:1; the surface layer comprises 76.2 percent of low-density polyethylene 582E, 23 percent of high-density polyethylene HD3355 and 0.8 percent of PA0801LD by mass percentage; the middle layer comprises, by mass, 25.3% of low density polyethylene 2420H, 13.5% of metallocene linear low density polyethylene, 41% of high density polyethylene H555JA, 19.5% of milky white master batch XP140026 and 0.7% of PA0801LD; the inner layer comprises 76.2% by mass of low density polyethylene 582E, 23% by mass of high density polyethylene HD3355 and 0.8% by mass of PA0801LD.
The preparation method was the same as in example 5, and a polyethylene composite film having a thickness of 40 μm was obtained.
Example 12
In the polyethylene composite film prepared in this embodiment, the mass ratio of the surface layer, the middle layer and the inner layer is 1:2:1; the surface layer comprises 74.2 percent of low-density polyethylene 582E, 25 percent of high-density polyethylene M6012EP and 0.8 percent of PA0801LD by mass percentage; the middle layer comprises 31.7 percent of low density polyethylene 2420H, 7 percent of metallocene linear low density polyethylene, 43 percent of high density polyethylene H555JA, 17.5 percent of milky white master batch XP140026 and 0.8 percent of PA0801LD by mass percentage; the inner layer comprises 74.2% by mass of low density polyethylene 2420H, 25% by mass of high density polyethylene M6012EP and 0.8% by mass of PA0801LD.
The preparation method was the same as in example 11, and a polyethylene composite film having a thickness of 40 μm was obtained.
Comparative example 2
In the polyethylene composite film prepared by the comparative example, the low-density polyethylene is FD0270 of Catal petrochemical Co., ltd, the melt index is 2.4g/10min, and the density is 0.923g/cm 3 (ii) a The high density polyethylene comprises 81841.27 of Dow chemical, the melt index is 6.0g/10min, and the density is 0.9470.923g/cm 3 (ii) a The high density polyethylene comprises Exxon HTA108, with a melt index of 0.7g/10min and a density of 0.961g/cm 3 (ii) a The milky white color master batch is 8000CN of the Schelman plastic company, the melt index is 11.5g/10min, and the density is 2.0g/cm 3 Titanium dioxide content 70wt.%; the processing aid is PEA-3S of the Huayi scientific and technological development limited company, the melt index is 2g/10min, and the density is 0.94g/cm 3 The content of the effective component is 3wt.%.
In the polyethylene composite film prepared by the comparative example, the mass ratio of the surface layer, the middle layer and the inner layer is 1:2:1; the surface layer comprises 74 percent of low-density polyethylene FD0270, 25 percent of high-density polyethylene 81841.27 and 1 percent of PEA-3S in percentage by mass; the middle layer comprises 40.5 percent of low-density polyethylene FD0270, 43 percent of high-density polyethylene HTA108, 15.5 percent of milky-white master batch 8000CN and 1 percent of PEA-3S in percentage by mass; the inner layer comprises 74 percent of low density polyethylene FD0270, 25 percent of high density polyethylene 81841.27 and 1 percent of PEA-3S in percentage by mass.
The preparation method was the same as in comparative example 1, and a polyethylene composite film having a thickness of 80 μm was obtained.
The polyethylene composite films obtained in examples 7 to 12 and comparative example 2 were tested for tensile strength, elongation at break, elastic modulus and gloss in accordance with the test methods of example 1, and the polyethylene composite films obtained in examples 7 to 12 and comparative example 2 were respectively tested for whiteness in accordance with GB/T2410-2008, and the test results are shown in Table 6.
TABLE 6 results of performance test of polyethylene composite films obtained in examples 7 to 12 and comparative example 2
Figure BDA0003000581570000181
As can be seen from Table 5, the polyethylene composite film provided by the invention has the longitudinal tensile strength of 164-188 MPa, the transverse tensile strength of 20.6-21.7 MPa and the longitudinal elongation at break of 90-110%, and is not easy to deform due to printing caused by stretching; the transverse breaking elongation is 705-735%, and the tensile property is excellent; the longitudinal elastic modulus is 775-830 MPa, the transverse elastic modulus is 778-836 MPa, the elastic modulus is high, and the stiffness is high; the whiteness is 80.5-82.5%, the glossiness is 98-115%, and the glossiness is high.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The polyethylene composite film is characterized by comprising a surface layer, a middle layer and an inner layer which are sequentially bonded;
the surface layer comprises first low-density polyethylene, first high-density polyethylene and a first processing aid; the melt index of the first low-density polyethylene is 1.8 to 4.0g/10min, and the density is 0.918 to 0.935g/cm 3 (ii) a The melt index of the first high-density polyethylene is 1.0 to 2.0g/10min, and the density is 0.950 to 0.962g/cm 3 ；
The middle layer comprises second low-density polyethylene, metallocene linear low-density polyethylene, second high-density polyethylene and a second processing aid; the melt index of the second low-density polyethylene is 1.5 to 2.0g/10min, and the density is 0.920 to 0.935g/cm 3 (ii) a The melt index of the metallocene linear low-density polyethylene is 0.8 to 2.0g/10min, and the density is 0.915 to 0.920g/cm 3 (ii) a The melt index of the second high-density polyethylene is 0.5 to 2.0g/10min, and the density is 0.950 to 0.962g/cm 3 ；
The inner layer comprises a third low density polyethylene, a third high density polyethylene and a third processing aid; the melt index of the third low-density polyethylene is 1.8 to 4.0g/10min, and the density is 0.918 to 0.935g/cm 3 (ii) a The melt index of the third high-density polyethylene is 1.0 to 2.0g/10min, and the density is 0.950 to 0.962g/cm 3 ；
The thickness of the polyethylene composite film is 30 to 40 mu m;
the first low density polyethylene is Shell 2420H or Dow chemical corporation 582E; the first high density polyethylene is HD3355 of Thai national energy and petrochemical company or M6012EP of Darls petrochemical company, samsung of Korea; the first processing aid is PA0801LD of Suzhou Constantol engineering plastics Co., ltd;
the second processing aid is PA0801LD from Constantol engineering plastics, inc., suzhou;
the third low density polyethylene is Shell 2420H or Dow chemical corporation 582E; the third high density polyethylene is HD3355 of Thai national energy and petrochemical company or M6012EP of Darls petrochemical company of Samsung Korea; the third processing aid is PA0801LD from Constantam engineering plastics, inc., suzhou.
2. The polyethylene composite film according to claim 1, wherein the mass ratio of the surface layer, the middle layer and the inner layer is (10 to 35): (30 to 80): (10 to 35).
3. The polyethylene composite film according to claim 1 or 2, wherein the surface layer comprises the following components in percentage by mass: 40-80% of first low-density polyethylene, 15-60% of first high-density polyethylene and 0.5-1.5% of first processing aid, wherein the mass percentage of all the components of the surface layer is 100%.
4. The polyethylene composite film according to claim 1 or 2, wherein the middle layer comprises the following components in percentage by mass: 30 to 70 percent of second low-density polyethylene, 5 to 20 percent of metallocene linear low-density polyethylene, 25 to 70 percent of second high-density polyethylene and 0.5 to 1.5 percent of second processing aid, wherein the sum of the mass percentages of the components of the middle layer is 100 percent.
5. The polyethylene composite film according to claim 1 or 2, wherein the inner layer comprises the following components in percentage by mass: 40-85% of third low-density polyethylene, 15-60% of third high-density polyethylene and 0.5-1.5% of third processing aid, wherein the mass percentages of the components of the inner layer are 100%.
6. The polyethylene composite film according to claim 1, wherein the middle layer further comprises a milky white color master batch.
7. A method for preparing the polyethylene composite film according to any one of claims 1 to 6, which is characterized by comprising the following steps:
co-extruding blown films by adopting a three-layer blown film co-extrusion method after melting and plasticizing the raw materials of the surface layer, the middle layer and the inner layer to obtain a primary composite film;
and sequentially carrying out longitudinal stretching and corona treatment on the primary composite film to obtain the polyethylene composite film.
8. The method according to claim 7, wherein the longitudinal stretch is at a ratio of 3 to 5.
9. The production method according to claim 7, wherein the corona treatment has an output of 3.5 to 5kW.
10. Use of the polyethylene composite film according to any one of claims 1 to 6 or the polyethylene composite film prepared by the preparation method according to any one of claims 7 to 9 as a label film fabric.
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