CN114456429A

CN114456429A - Gas-barrier water-blocking laminated film, preparation method and application thereof in packaging

Info

Publication number: CN114456429A
Application number: CN202210113706.3A
Authority: CN
Inventors: 曾一鸣; 巫妍; 袁独军
Original assignee: Shanghai Lingyu Technology Co ltd
Current assignee: Shanghai Lingyu Technology Co ltd
Priority date: 2022-01-30
Filing date: 2022-01-30
Publication date: 2022-05-10
Anticipated expiration: 2042-01-30
Also published as: CN114456429B

Abstract

A kind of resistanceA gas barrier laminated film comprising a polyolefin or olefin copolymer resin substrate based on an ethylene or propylene monomer; a barrier primer coating layer formed on one or both surfaces of the resin substrate; an aluminum metal deposition layer formed on the barrier primer coating; wherein the barrier primer coating is formed by coating and drying a coating liquid and curing and crosslinking through electron beam radiation; the coating liquid includes: selected from Si (OR)¹)₄… (1) or a hydrolysate thereof, wherein R is¹Is one of methyl or ethyl, a polymer A containing carboxyl and a polymer B containing hydroxyl. The gas-barrier water-blocking laminated film not only has excellent barrier property, but also has mechanical properties such as flexibility, tensile strength and the like, and can meet the requirement of recycling as a single material.

Description

Gas-barrier water-blocking laminated film, preparation method and application thereof in packaging

Technical Field

The invention relates to the technical field of packaging films, in particular to a gas-barrier water-blocking laminated film, a preparation method and application thereof in packaging.

Background

In order to prevent the food, medicine and other products in the package from going bad, rotten or changing other properties, the packaging material used generally needs to have certain oxygen barrier property and water vapor barrier property to prolong the shelf life of the packaged contents, especially the color and flavor of the food. The prior packaging material improves the gas and water vapor barrier property, particularly the oxygen barrier property of the packaging material by a plurality of coating layers or a multi-layer composite method.

Polyolefin materials such as polyethylene, polypropylene, and copolymers of ethylene or propylene with other olefin monomers are currently the most widely used packaging materials. Recycling of these packaging materials is an important issue to reduce environmental pollution and carbon emissions throughout the industry. In order for polyolefin materials to be suitable packaging materials, it is necessary to modify the packaging materials made of polyolefin so that the packaging materials have oxygen barrier properties and water vapor barrier properties that meet the packaging requirements. The ideal packaging material not only needs to meet the barrier requirement, but also needs to meet the requirement that the volume fraction of the single type of polyolefin used is not less than 90 percent, so that the resin material obtained after re-melting and mixing after recycling has the performance similar to that of the original material, thereby being capable of being re-processed and reused.

One possible approach in the prior art is to use sheet materials having high barrier properties to composite with packaging materials to provide the desired barrier properties, such as by compounding with metal foil to make a barrier laminate. One common metal foil is aluminum foil. Further, one or more layers of an ethylene-vinyl alcohol copolymer or the like may be compounded. However, this solution requires additional lamination of additional layers that are thermodynamically incompatible with the original packaging base film thickness, and once the lamination is completed, the materials of the layers are difficult to separate again through subsequent processing, so that the obtained laminate is difficult to recycle, does not meet the requirement of recycling as a single material, and can only be buried as a waste product, resulting in waste of resources and destruction of the environment. An example of such a solution is described in patent document US2004/0053054A 1.

In addition, a coating layer with barrier property can also be obtained by coating a solution or emulsion containing the barrier material on the surface of the base material and then drying. For example, by coating polyvinylidene chloride (PVDC) emulsion, barrier laminates with good oxygen barrier properties can be obtained. However, the chlorine-containing coating material may generate toxic exhaust gas during combustion, which is a potential environmental problem. For example, a coating layer having oxygen barrier properties can also be obtained by applying an aqueous coating solution containing polyvinyl alcohol to obtain a polyvinyl alcohol coating layer. However, coatings prepared by aqueous solution coating often have difficulty providing good water vapor barrier properties, and even in environments with high humidity, there may be problems with the barrier properties decreasing. An example of such a solution is disclosed in patent document US2011/0097528a 1.

In order to make the barrier layer obtained by coating more compact and improve the barrier property and the water vapor tolerance property, one proposal is to use a silane coupling agent containing a group capable of reacting with carboxyl as a cross-linking agent in a coating liquid containing a polymer with carboxyl to improve the cross-linking density of the polymer. Common coupling agents include silane coupling agents containing epoxy, amino, mercapto, and like groups. However, this approach requires the addition of additional coupling agents and, for example, compounds containing epoxy groups have potential for gene mutagenicity and present health risks; small molecule compounds containing amino groups and sulfhydryl groups can generate peculiar smell which can be sensed by workers and consumers in the processes of production and storage. An example of such a solution is disclosed in patent document US8039071B 2.

Another possible solution is to add a layer of coating material with low thickness and high barrier properties to the packaging material substrate by physical or chemical means. For example, an inorganic oxide coating, such as an aluminum oxide coating, a silicon oxide coating, or the like, is added on the polymer resin substrate by chemical vapor deposition, physical vapor deposition, or the like. However, barrier materials based on a single oxide coating have poor resistance to deformation, and are prone to significantly reduced barrier properties due to deformation, dropping, impact, and the like of the package; meanwhile, the inorganic oxide coating has poor water vapor barrier property. Examples of such solutions are US4559167A, US2015/0331153a 1.

In addition, a layer of compact inorganic simple substance plating layer, such as an aluminum plating layer, is added on the polymer resin substrate by chemical vapor deposition, physical vapor deposition and other methods, so that the oxygen barrier property and the water vapor barrier property of the film can be improved simultaneously. However, since the surface energy of the polyolefin material is low, the adhesion strength between the metal plating layer directly coated on the surface of the polyolefin and the polyolefin film is generally low, and the metal plating layer and the polyolefin film are easily damaged by external force such as scraping and water immersion, and the composite layer such as the printing layer and the heat sealing layer compounded on the surface of the aluminum is easily peeled from the base film, thereby reducing the barrier property of the packaging material, and even causing appearance damage. In order to solve the problem, other thin film materials with strong polarity and high surface energy can be attached to the surface of the polyolefin to serve as a medium for attaching the aluminum layer. However, also in this type of solution, the need arises for the addition of other types of film, of a thickness comparable to that of the base film, and the packaging film obtained does not meet the requirements of recycling as a single material. An example of such a solution is disclosed in patent document CN 112519369A. Another solution is to coat a primer layer with higher polarity on the surface of the polyolefin base film before aluminizing. Such primer layers are typically polyurethane, polyacrylate type materials. Such primer layers are generally classified into organic solvent-based and aqueous primer layers according to the dispersion medium. The obtained primer layer has good water resistance by adopting the organic solvent type primer layer, but the organic solvent needs to be additionally processed to meet the requirement of environmental protection. With aqueous primer coatings, the handling of large amounts of organic solvents can be avoided, but the resulting primer coating, due to its hydrophilic nature, requires the design of an appropriate crosslinking scheme to improve the primer water resistance. Meanwhile, in the scheme, an additional bottom coating work is required before aluminum plating, and after the aluminum plating is finished, subsequent coating or addition of other additional layer materials is required to enable the composite film to meet the requirement of oxygen water vapor barrier required by packaging. An example of such a solution is disclosed in patent document CN 103866607B.

Disclosure of Invention

The invention solves the technical problem of providing a gas-barrier water-blocking laminated film which can be used for packaging various foods, has excellent oxygen barrier property and water vapor barrier property, has better mechanical properties such as flexibility, tensile strength and the like, and is convenient to recycle.

In order to solve the above-mentioned problems, the inventors have made experiments and studies to provide a gas-and water-barrier laminated film, comprising: a polyolefin or olefin copolymer resin substrate based on ethylene or propylene monomers; a barrier primer coating layer formed on one or both surfaces of the resin substrate; an aluminum metal deposition layer formed on the barrier primer coating; wherein the barrier primer coating is formed by coating a coating liquid, drying the coating liquid and curing and crosslinking through electron beam radiation; the coating liquid includes: selected from Si (OR)¹)₄… (1) or a hydrolysate thereof, wherein R is¹Is one of methyl or ethyl; a carboxyl group-containing polymer A; a hydroxyl group-containing polymer B; the thickness of the barrier primer coating is not more than 1000 nm; the thickness of the aluminum metal deposition layer is 1 nm-100 nm.

Optionally, the coating liquid is irradiated by a beam current electron beam with 150keV, and the irradiation dose of the electron beam is 25 kGy-60 kGy (based on the total weight of the barrier primer coating).

Optionally, the gas and water barrier laminated film has an Oxygen Transmission Rate (OTR) of less than 1 ml/(m) at 23 ℃ in an atmosphere of 50% relative humidity²Day atm), a Water Vapor Transmission Rate (WVTR) of less than 1 g/(m) at 37.8 ℃ and 90% RH²Day atm), peel strength of ethylene-acrylic acid copolymer (EAA) at 23 ℃ and 54% relative humidity not less than 1.6N/15 mm.

Optionally, polymer B is partially or fully alcoholyzed polyvinyl alcohol or a copolymer of ethylene with vinyl alcohol and vinyl alcohol ester.

Optionally, the resin substrate is selected from biaxially oriented polypropylene (BOPP) or cast polypropylene (CPP) or Cast Polyethylene (CPE).

The invention also provides a preparation method of the gas-barrier water-blocking laminated film, which comprises the following steps: a step (1) of coating and drying a coating liquid on one or both surfaces of a polyolefin or olefin copolymer resin substrate based on an ethylene or propylene monomer to obtain a barrier primer coating; the coating liquid includes: selected from Si (OR)¹)₄… (1) or a hydrolysate thereof, wherein R is¹Is one of methyl or ethyl; a carboxyl group-containing polymer A; a hydroxyl group-containing polymer B; step (2), curing and crosslinking the barrier primer coating by electron beam radiation; and (3) depositing a layer of metal aluminum on the surface of the barrier priming coating to form an aluminum metal deposition layer, wherein the thickness of the aluminum metal deposition layer is 1-100 nm.

Optionally, in the step (2), the coating liquid is irradiated by a 150keV beam electron beam, and the irradiation dose of the electron beam is 25kGy to 60kGy (based on the total weight of the barrier primer coating).

Optionally, the resin substrate is corona treated prior to step (1).

Optionally, in step (3), vacuum pumping is performed in the evaporation chamber to 2 × 10^-5mbar, heating a heat source in the chamber to 1500 ℃, putting the aluminum wire in the evaporation chamber, gasifying the aluminum wire into aluminum steam, diffusing the aluminum steam into the evaporation chamber, and depositing the aluminum steam on the surface of the resin substrate introduced by the coating drum, wherein the rotating speed of the coating drum is 500-1000 m/min.

The invention also provides application of the gas-barrier water-blocking laminated film.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects: the barrier priming coating and the aluminum metal deposition layer are formed on the surface of the resin substrate by adopting a liquid coating and vacuum evaporation method, so that only one-time coating is needed, the composite gas-barrier water-blocking laminated film has enough interlayer bonding strength and mechanical strength, particularly the bonding strength between the aluminum metal deposition layer and the barrier priming coating layer, and simultaneously has the tolerance to water immersion and high-humidity environment, and can be rolled into a roll sample for transportation, storage and subsequent lamination and printing, and obvious barrier performance reduction can not occur in the rolling and transportation process.

Drawings

FIG. 1 is a schematic view showing the formation of a water-insoluble crosslinked network of a polymer in a coating liquid of a gas-and water-barrier laminated film of the present invention;

fig. 2 is a schematic view of the structure of the gas and water barrier laminated film of the present invention.

Detailed Description

Some embodiments according to the invention will be described in more detail below with reference to the accompanying drawings. It is to be understood that other various embodiments can be devised and modified by those skilled in the art in light of the teachings herein without departing from the scope or spirit of the invention.

Unless otherwise indicated, all numbers expressing feature sizes, quantities, and physical properties used in the specification and claims are to be understood as being modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can be varied as appropriate by one skilled in the art based on the teachings of the present invention to obtain the desired properties. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range, e.g. 1 to 100 includes 1, 1.1, 1.3, 2, 2.75, 3, 3.84, 5, 10, 20.05, 50, 75, 100, etc.

Unless otherwise indicated, the raw materials used in the examples and comparative examples of this specification were all commercially available and were commercially available.

Resin films are widely used as substrates for packaging materials. Because it is usually used in the form of a thin layer, it cannot be reused many times, but becomes waste after one-time use. And because it is commonly used for packaging daily consumer goods with huge output, the total amount of resin films as wastes is huge. Only a small part of the waste resin film can be recycled, and most of the waste resin film is incinerated or buried as garbage. Currently, Polyethylene (PE), polypropylene (PP), and other polyolefin materials based on ethylene and propylene monomers and containing other comonomers are most commonly selected as resin substrates in view of economy and recycling performance.

In many application scenarios, a polyolefin or olefin copolymer resin substrate (resin film) of ethylene or propylene monomer needs to be compounded to obtain a composite thin layer material (laminated film) satisfying various properties such as mechanical properties, barrier properties and the like required for a packaging material. Due to the thermodynamic incompatibility among the composite layers, the laminated film cannot be directly recycled, so that the waste of raw materials and the environmental pollution are caused. In contrast, by adding a barrier layer for improving the barrier property of the resin substrate on the resin substrate which is easy to recycle, the resin substrate can obtain additional barrier property on the premise of keeping the recyclability of the resin substrate so as to meet the barrier requirement of applications such as packaging materials. The volume fraction of the resin substrate used may be 50% to 99% in the composite laminated film, and is preferably 80% to 99%, more preferably 90% to 99%, in view of recycling requirements. The thickness of the resin substrate may be generally between 1 μm and 1000. mu.m, preferably between 1 μm and 500. mu.m, and more preferably between 10 μm and 100. mu.m.

The inorganic metal deposition layer added on the surface of the resin substrate can obviously improve the oxygen barrier property and the water vapor barrier property of the obtained laminated film due to the compact characteristic. The metal used to enhance barrier properties may be selected from aluminum. However, since polyolefin or olefin copolymer as a monomer of ethylene or propylene as a resin substrate has a weak polarity and a low surface energy, the adhesion between the inorganic metal plating layer directly deposited on the surface of the resin substrate and the resin substrate is poor, and thus, the defects such as cracks, perforations, and plating peeling are easily caused by bending, scratching by impact or external force, water immersion, etc., resulting in a decrease in barrier properties of the laminated film and even a deterioration in appearance. In order to improve the adhesion between the metal deposition layer and the resin substrate, the embodiment of the invention coats a barrier primer coating layer with higher polarity on the surface of the polyolefin resin substrate in a solution coating mode before vacuum evaporation so as to improve the adhesion between the metal deposition layer and the resin substrate.

Because polyolefins are less polar and have lower surface energies (e.g., polyethylene has a surface energy of about 31dynes/cm at 20 ℃) and aluminum has a higher surface energy (about 850dynes/cm at 20 ℃), aluminum deposits are less likely to form strong van der waals bonds with polyolefin resin substrates. In order to improve the adhesion between the metal deposition layer and the polyolefin resin substrate, a primer coating having a surface energy between that of polyolefin and aluminum metal is previously applied between the metal deposition layer and the polyolefin resin substrate. In order to improve the oxygen barrier property of the obtained laminated film while obtaining the primer coating, the polymer selected for the primer coating of the present invention may be selected from at least one of polymers B having hydroxyl groups as a barrier primer coating; a combination of multiple hydroxyl-containing polymers B can also be selected as a barrier primer coating. For example, polyvinyl alcohol has a surface energy of about 37dynes/cm at 20 ℃, and a barrier primer coating made from polyvinyl alcohol as a main raw material can form a strong bond with the surface of a polyolefin resin substrate having a similar surface energy to that of aluminum metal having an extremely high surface energy by van der waals force. Moreover, hydrogen bonds can be formed among the hydroxyl groups in the barrier primer coating, so that the diffusion of oxygen molecules in the barrier primer coating is hindered, and the oxygen barrier property of the laminated film can be remarkably improved. To improve the water resistance of the barrier primer coating, a suitable crosslinking agent is provided to crosslink the polymer.

The invention selects the compound satisfying the general formula of Si (OR)¹)₄… (1) as a crosslinking agent, the Si-OH groups formed by hydrolysis of (1) can condense with the hydroxyl groups of the hydroxyl group-containing polymer B to form a water-insoluble crosslinked polymer network, as shown in FIG. 1. The hydroxyl group-containing polymer B may be selected from polymers such as polyvinyl alcohol compounds obtained by partially or totally alcoholyzing polyvinyl acetate, and copolymers obtained by copolymerizing one or more of ethylene, vinyl alcohol and vinyl alcohol ester. To further improve the adhesion between the barrier primer coating and the polyolefin resin substrate, the polyolefin resin substrate may optionally be corona treated or may be pre-coated with a primer coating, such as a polyol and a polyolefin resinThe polyisocyanate reacts and crosslinks to form the primer coating.

Although the barrier primer coating mainly comprising the hydroxyl group-containing polymer B has a similar surface energy to that of the polyolefin resin substrate and can form a strong adhesion, the surface energy of the aluminum metal deposition layer is still significantly different from that of the barrier primer coating, and it is difficult to form a strong adhesion of the aluminum layer by van der waals force alone. In order to improve the adhesion between the aluminum metal deposition layer and the barrier primer coating layer, the present invention selects at least one selected from a carboxyl group-containing polymer a (e.g., polyacrylic acid, partially neutralized products of polyacrylic acid, acrylic acid copolymers and partially neutralized products thereof, or other carboxyl group-containing polymers and partially neutralized products thereof) to be added to the barrier primer coating liquid for coating. The carboxyl has acidity, so carboxyl anions and metal cations can be generated by reaction between the carboxyl and the active metal deposition layer, and an interface layer with strong interaction is formed between the anions and the cations through electrostatic adsorption, so that the adhesive force between the aluminum metal deposition layer and the barrier priming coating layer is remarkably improved. Because carboxyl has important contribution to the adhesive force between the aluminum metal deposition layer and the blocking priming coat, when the raw material of the blocking priming coat is selected from a partially neutralized product of polyacrylic acid or a partially neutralized product of an acrylic acid copolymer, or the laminated film is processed subsequently, the proportion of carboxyl contained in the obtained final gas-resistant water-resistant laminated film is not too low, and therefore, measures are taken to limit the degree of reactions such as-COOH group neutralization, esterification and the like in the coating liquid; the molar fraction of carboxyl groups in the barrier layer of the laminated film to the total substituents containing-COO-groups may be selected from 50% to 100%, preferably from 60% to 100%, more preferably from 70% to 100%.

In order to fix the added carboxyl-containing polymer A and improve the water resistance and the barrier property of the obtained barrier primer coating, the invention adopts an electron beam radiation mode to further introduce crosslinking into the barrier primer coating. Due to the electron withdrawing effect of the carboxyl, the density of electron clouds around carbon atoms connected with the carboxyl is lower, free radicals are easier to form due to excitation of radiation energy, and the conjugated effect between the free genes and adjacent carbon-oxygen double bonds has longer service life, so that covalent bonds can be formed between the free genes and adjacent molecules to generate crosslinking, and the compactness of the barrier priming coating is improved. The radiation dose selected by the invention is between 25kGy and 60kGy (based on the total weight of the barrier priming coating), and the energy of an electron beam is 150 keV.

The obtained gas-and water-barrier laminated film can be melt-kneaded at a temperature higher than the melting point of the resin substrate to prepare a resin master batch. The remixed resin master batch should have similar mechanical properties to the original master batch for the purpose of recycling, so as to be remolded. In view of this recycling requirement, the additional barrier primer coating in the gas and water barrier laminated film should not be too thick. When the volume fraction of the barrier primer coating in the gas-barrier water-blocking laminated film does not exceed 10% of that of the resin substrate, the gas-barrier water-blocking laminated film has certain recycling property; the gas and water barrier laminated film has better recyclability when the volume fraction of the barrier primer coating layer in the gas and water barrier laminated film is not more than 5% of the resin substrate. The typical thickness of resin substrates currently used in the food packaging industry is from 10 μm to 100 μm. Therefore, when the thickness of the coated barrier primer coating is less than 1 mu m (1000nm), the obtained gas-barrier water-blocking laminated film has certain recycling performance; when a resin substrate is used which is thick, the thickness of the barrier primer coating can be suitably increased.

The barrier priming coating is an aqueous coating liquid and can be carried out by solution dip coating, solution spray coating, wire bar coating, anilox roll coating, micro-gravure roll coating, reverse coating, blade coating and the like. The obtained coating liquid can be dried by one or more of hot air drying, microwave heating drying, hot roller drying, radiation drying, infrared irradiation, etc.

In view of the economic and environmental requirements of the solution, water is preferred as a solvent for the coating liquid in the present invention. In order to improve the solubility of the compound (1) and the polymer in the coating solution, an alcohol compound such as methanol, ethanol, or isopropyl alcohol may be optionally added. In order to satisfy other performance requirements of the obtained laminated film as a packaging material, a defoaming agent, an antioxidant, a colorant, an inorganic filler, a tackifier, and the like may be optionally added to the coating liquid.

After the barrier primer coating is obtained by coating the aqueous coating liquid, the invention adopts a Physical Vapor Deposition (PVD)/vacuum evaporation scheme to deposit an aluminum layer on the surface of the barrier primer coating as an inorganic metal deposition layer, so as to further improve the oxygen barrier property and the water vapor barrier property of the obtained gas-barrier water-blocking laminated film. This should not be seen as limiting the method of adding the metal deposition layer; other options, such as Chemical Vapor Deposition (CVD), solution coating, colloidal coating, electrochemical methods, etc., may be selected by the manufacturer having ordinary knowledge in the art to obtain the desired aluminum metal deposition layer. The thickness of the aluminum metal deposition layer is preferably between 1nm and 100 nm.

To increase the degree of crosslinking of the polymer in the barrier primer coating, this can be achieved by heat treating the resulting laminated film either before or after vacuum vapor deposition of aluminum. The subsequent heat treatment can accelerate the reaction of the-Si-OH group and the hydroxyl in the polymer, thereby improving the crosslinking degree of the laminated film and improving the barrier property and the water resistance of the laminated film. The heat treatment temperature can be selected to be between 40 ℃ and 100 ℃.

In order to prepare the gas-barrier water-blocking laminated film meeting the production requirements, the gas-barrier water-blocking laminated film can be added with a heat-sealing layer for heat sealing, a printing layer for ink adhesion and other multilayer materials through subsequent compounding, and the additional materials such as the heat-sealing layer, the printing layer and the like can be combined with the gas-barrier water-blocking laminated film into a composite packaging film through methods such as gluing, hot pressing and the like in different orders.

The gas-barrier water-blocking laminated film is economical and environment-friendly, can provide excellent oxygen barrier performance and water vapor barrier performance, has high aluminum deposition layer adhesion fastness, and has uniform and smooth appearance; in the production process, the laminated film can be prepared through a coating process and an aluminum evaporation process, and the operation is simple and easy to realize; after the film is rolled into a roll sample, the barrier property of the film is not obviously reduced. Under the typical application scene of meeting the strength requirement of a packaging material, the mass fraction of the blocking primer coating and the aluminum metal deposition layer in the gas-blocking and water-blocking laminated film accounts for less than 10%, and the gas-blocking and water-blocking laminated film still has excellent oxygen blocking property and water vapor blocking property, so that the gas-blocking and water-blocking laminated film can have mechanical properties such as flexibility, tensile strength and the like similar to those of a polyolefin or olefin copolymer resin substrate, and can be applied to an environment-friendly recyclable packaging manufacturing process with a single resin material as a main body.

To further illustrate the embodiments and characteristics of the present invention, practical experimental examples and comparative examples are listed below. The examples and comparative examples were tested and compared according to the following test methods (1) to (8), and the test results are shown in the attached tables.

Solution coating

In order to obtain the barrier primer coating with higher surface energy on the surface of the polyolefin resin substrate, a primer coating is adhered to the polyolefin resin substrate in a solution mixing, solution coating and subsequent drying mode. The specific embodiments are illustrated in the following description of the examples.

Electron beam radiation curing

In order to improve the crosslinking degree of the blocking priming coating and improve the compactness, the blocking property and the water resistance of the blocking priming coating, the invention adopts 150keV beam electron beams to carry out radiation treatment on the coated blocking priming coating, and the radiation dose is selected from 25kGy to 60kGy (based on the total weight of the blocking priming coating).

Vacuum aluminum plating

In order to improve the barrier effect, an aluminum (Al) metal deposition layer is required to be evaporated on the composite substrate with the barrier primer coating in a vacuum manner. To obtain a laminate with an aluminum metal deposition layer, a vacuum is applied in the deposition chamber to 2 × 10^- ⁵mbar and the heat source (evaporation boat) in the chamber was heated to 1500 ℃. The aluminum wire is vaporized into aluminum vapor on the evaporation boat and diffused into the evaporation chamber, and deposited on the surface of the resin substrate introduced through the coating drum. The aluminum plating thickness can be adjusted by the rotation speed of the coating drum, the sample injection speed of the aluminum wire and the like, and the linear speed of the substrate can be generally between 300m/min and 1000m/min, preferably between 500m/min and 1000m/min, so as to obtain an aluminum deposition layer with the thickness of about 42 nm.

FIG. 2 showsA cross-sectional view of one example of the gas and water barrier laminated film of the present invention. The laminated film comprises a polyolefin resin substrate (1), a barrier primer coating layer (2) formed on the resin substrate by solution coating and drying, and an aluminum metal deposition layer (3) further laminated thereon by vacuum evaporation. The polymer containing carboxyl in the barrier primer coating reacts with aluminum in the aluminum metal deposition layer to generate corresponding carboxyl anion (-COOH)^-) With aluminium cations (Al)³⁺) And are joined by electrostatic attractive interaction at the interface of the barrier primer coating and the aluminum metal deposition layer.

Test method (1): oxygen barrier properties

Oxygen barrier properties of the laminated film were measured according to ASTM D3985 using an OX-TRAN 2/22H model analyzer manufactured by AMETEK MOCON to obtain an Oxygen Transmission Rate (OTR) of the laminated film at 23 ℃ and 50% Relative Humidity (RH).

Test method (2): water vapor barrier properties

Water vapor barrier Properties of the laminated film were measured according to ASTM F1249 using an analyzer model PERMATRAN-W3/34H manufactured by AMETEK MOCON to obtain a Water Vapor Transmission Rate (WVTR) of the laminated film at 37.8 ℃ and 90% RH.

Test method (3): fastness of metal deposition layer

The method comprises the steps of testing the bonding strength between an aluminum metal deposition layer and a polyolefin resin substrate attached with a barrier primer coating, firstly, attaching a layer of ethylene-acrylic acid copolymer (EAA) film to the surface of the obtained aluminum metal deposition layer or the barrier primer coating in a heat sealing mode, then cutting a sample strip with the width of 15mm, carrying out tearing-off experiment on a tensile testing machine along the length direction of a sample to test the interlayer peeling strength between the EAA film and a laminated film, and simultaneously recording the condition that an aluminum layer is transferred to the EAA film. In the test used by the invention, the heat sealing compounding is carried out at 105 ℃, the tensile test is carried out at 23 ℃ and 54% Relative Humidity (RH), and the extension speed of the test machine head of the tensile tester is 300 mm/min.

Test method (4): appearance of metal deposition layer

The metal deposition layer of the obtained laminated film was subjected to appearance inspection by cutting a sample having a size of 10cm × 10cm and visually inspecting under a fluorescent lamp. The cut and gathered sample is placed in front of a fluorescent lamp, and the sample is observed to have appearance defects such as cracks, peeling, perforation and the like. In the testing process of the invention, the prepared metal deposition layer has no crack or peeling, so the testing only observes and counts the perforation defects of the metal deposition layer on the surface of the cut sample film, and records the number of perforations.

Test method (5): gel fraction test

The obtained laminated film was tested for gel ratio in the barrier primer to evaluate the degree of crosslinking of the primer. The test method comprises the following steps: a sample of a laminated film which had been coated and irradiated with an electron beam but had not been aluminized and had a length of 27cm and a width was cut out, and the weight M was measured₀. Placing the sample in 500ml deionized water, heating in 80 deg.C water bath for 60 min, taking out the residual laminated film, drying in 80 deg.C oven for 24 hr, and weighing the residual laminated film weight M₁. An uncoated resin substrate was cut into a 27cm sample, and the weight M was measured. The gel fraction was calculated as f ═ M (M)₁-M)/(M₀-M). This was repeated three times. The actual test results are the average of the test results of three samples.

Test method (6): water immersion test

The obtained laminated film was subjected to water immersion appearance inspection. The test method comprises the steps of shearing a laminated film sample with the length and the width of 10cm, placing the laminated film sample in 500ml of deionized water, preserving the temperature in a water bath at 30 ℃ for 5 hours, and checking whether the laminated film has defects of perforation, peeling, layering and the like. If there is no obvious change in appearance, it is marked as +; if appearance defects appear, it is marked as-.

Test method (7): barrier coating thickness test

The thickness of the coating layer of the obtained laminated film was measured by observation under a Scanning Electron Microscope (SEM).

Test method (8): tensile Property test

The uncoated, non-aluminized resin substrate and the coated or coated and aluminized laminated film can be subjected to a tensile property test to evaluate their recycling properties. The testing method comprises the steps of taking a proper amount of resin substrates or laminated films, mixing and extruding the resin substrates or the laminated films again in a double-screw extruder, flattening the resin substrates or the laminated films by a hot press, cutting the resin substrates or the laminated films into tensile sample bars with proper shapes by a die, carrying out tensile test according to ASTM D638, obtaining the tensile property of resin material matrixes, and recording the yield strength and the elongation at break; the length-diameter ratio of the used double-screw extruder is 40, the diameter of the screw is 11mm, the mixing temperature is 200 ℃, the mixing speed is 200rpm, and the mixing duration is 10 minutes; the temperature of a hot table of the hot press is 180 ℃, and the thickness of the flattened sample film is 1 mm; the tensile bars were measured according to ASTM D638 at a tensile speed of 120 mm/min.

Example 1

To obtain a coating liquid necessary for a gas-and water-blocking laminated film, first, polyacrylic acid (PAA, number average relative molecular mass Mn of 200,000) having a mass of 20g, polyvinyl alcohol (PVA, number average relative molecular mass Mn of 86,000) having a mass of 20g, and ammonia water having a mass of 0.16g were dissolved in deionized water having a mass of 503g with stirring to obtain a solution (a); tetramethoxysilane (TMOS) having a mass of 60g, 0.1N hydrochloric acid having a mass of 11g, and methanol having a mass of 60g were dissolved in deionized water 101g, and stirred for 1 hour to obtain a solution (B); the obtained solution (B) was mixed with the solution (a) to obtain a solution (II).

In order to obtain the gas-barrier water-blocking laminated film, the solution (II) is uniformly coated on the surface of a biaxially oriented polypropylene (BOPP) base film with the thickness of 18 mu m by a wire bar coater, after drying, the solution is irradiated by electron beam radiation with the irradiation dose of 25kGy, and an aluminized (Al) metal deposition layer with the thickness of 42nm is integrated on the solution by a vacuum vapor deposition layer, so that the gas-barrier water-blocking laminated film (I) is obtained, and the structure is BOPP/barrier primer/Al (base film/barrier primer/metal layer, s/p/m), wherein the thickness of the barrier primer is about 0.9 mu m.

Example 2

In order to obtain the gas-barrier water-blocking laminated film, the solution (II) is uniformly coated on the surface of a biaxially oriented polypropylene (BOPP) base film with the thickness of 18 mu m by a wire bar coater, after drying, the solution is irradiated by electron beam radiation with the irradiation dose of 60kGy, and an aluminized (Al) metal deposition layer with the thickness of 42nm is integrated on the solution by a vacuum vapor deposition layer to obtain the gas-barrier water-blocking laminated film (I) with the structure of BOPP/barrier primer coating/Al (s/p/m), wherein the thickness of the barrier primer coating is about 0.9 mu m.

Example 3

To obtain a coating liquid necessary for a gas-and water-blocking laminated film, first, polyacrylic acid (PAA, number average relative molecular mass Mn of 200,000) having a mass of 97g, polyvinyl alcohol (PVA, number average relative molecular mass Mn of 86,000) having a mass of 3g, and ammonia water having a mass of 0.7g were dissolved in deionized water having a mass of 899.3g with stirring to obtain a solution (a); tetramethoxysilane (TMOS) having a mass of 22.3g, 0.1N hydrochloric acid having a mass of 3.5g, and methanol having a mass of 22.4g were dissolved in 51.8g of deionized water and stirred for 1 hour to obtain a solution (B); the obtained solution (B) was added to 172.8g of the solution (A) by mass to obtain a solution (II).

Example 4

To obtain a coating liquid necessary for obtaining a gas-and water-blocking laminated film, materials such as PAA, PVA, TMOS were dissolved and mixed in the same procedure as in example 1 to obtain a solution (II).

In order to obtain the gas-barrier water-blocking laminated film, the solution (II) is uniformly coated on the surface of a casting polypropylene (CPP) base film with the thickness of 25 mu m by a wire bar coater, after drying, the solution is irradiated by electron beam radiation with the irradiation dose of 60kGy, and an aluminized (Al) metal deposition layer with the thickness of 42nm is deposited on the solution by a vacuum gas phase deposition layer to obtain the gas-barrier water-blocking laminated film (I) with the structure of CPP/barrier primer coating/Al (s/p/m), wherein the thickness of the barrier primer coating is about 0.9 mu m.

Example 5

In order to obtain the gas-barrier water-blocking laminated film, the solution (II) is uniformly coated on the surface of a Casting Polyethylene (CPE) base film with the thickness of 40 mu m by a wire bar coater, after drying, the solution (II) is irradiated by electron beams with the irradiation dose of 60kGy, and an aluminized (Al) metal deposition layer with the thickness of 42nm is integrated on the solution (II) by a vacuum vapor deposition layer to obtain the gas-barrier water-blocking laminated film (I) with the structure of CPE/barrier primer coating/Al (s/p/m), wherein the thickness of the barrier primer coating is about 0.9 mu m.

Example 6

To obtain a coating liquid necessary for a gas-and water-blocking laminated film, first, polyacrylic acid (PAA, number average relative molecular mass Mn of 200,000) having a mass of 20g, polyvinyl alcohol (PVA, number average relative molecular mass Mn of 86,000) having a mass of 20g, and ammonia water having a mass of 0.16g were dissolved in deionized water having a mass of 503g with stirring to obtain a solution (a); tetraethoxysilane (TEOS) of 78g in mass, 0.1N hydrochloric acid of 11g in mass, and methanol of 60g in mass were dissolved in 101g of deionized water, and stirred for 1 hour to obtain a solution (B); the obtained solution (B) was mixed with the solution (a) to obtain a solution (II).

Example 7

50g of the gas-and water-resistant laminated film obtained in example 4 was kneaded and extruded by a twin-screw extruder in accordance with test method (8), and the extruded sample was pressed flat by a hot press and cut into a sample piece, and the tensile properties were measured to record the yield strength and elongation at break of the sample piece.

Example 8

50g of the gas-and water-resistant laminated film obtained in example 5 was kneaded and extruded by a twin-screw extruder in accordance with test method (8), and the extruded sample was pressed flat by a hot press and cut into a sample piece, and the tensile properties were measured to record the yield strength and elongation at break of the sample piece.

Comparative example 1

To obtain a coating liquid necessary for a laminated film, first, polyvinyl alcohol (PVA, number average relative molecular mass Mn of 86,000) having a mass of 40g was dissolved with stirring in deionized water having a mass of 503g to obtain a solution (a); tetramethoxysilane (TMOS) having a mass of 60g, 0.1N hydrochloric acid having a mass of 11g, and methanol having a mass of 60g were dissolved in deionized water 101g, and stirred for 1 hour to obtain a solution (B); the obtained solution (B) was mixed with the solution (a) to obtain a solution (II).

In order to obtain a laminated film, the solution (II) is uniformly coated on a biaxially oriented polypropylene (BOPP) base film with the thickness of 18 μm by a wire bar coater, after drying, the solution is irradiated with electron beam radiation with the dose of 60kGy, and an aluminum (Al) plated metal deposition layer with the thickness of 42nm is deposited on the solution by vacuum vapor deposition to obtain the laminated film (I) with the structure of BOPP/barrier primer/Al (s/p/m), wherein the thickness of the barrier primer is about 0.9 μm.

Comparative example 2

A CPP film having a thickness of 25 μm was used as a resin substrate, on which an aluminum (Al) plated metal deposition layer having a thickness of 42nm was first deposited by vacuum vapor deposition. Solution (II) was prepared using the same method as in example 1, and uniformly applied to the surface of the above-mentioned metal deposition layer from a wire bar coater, dried, and irradiated with electron beam radiation at a dose of 60kGy to obtain a laminate (s/m/p) having a barrier layer thickness of about 0.9 μm and a CPP/Al/barrier layer structure.

Comparative example 3

A CPP film with the thickness of 25 mu m is used as a resin substrate, electron beam radiation with the dosage of 60kGy is irradiated, and an aluminum (Al) plated metal deposition layer with the thickness of 42nm is deposited on the CPP film by vacuum vapor deposition, and the structure is CPP/Al (s/m).

Comparative example 4

A BOPP film with the thickness of 18 mu m is used as a resin substrate, electron beam radiation with the dose of 60kGy is irradiated, and an aluminum (Al) plated metal deposition layer with the thickness of 42nm is deposited on the resin substrate in a vacuum vapor deposition mode, and the structure is BOPP/Al (s/m).

Comparative example 5

Using a CPE film with the thickness of 40 mu m as a resin substrate, irradiating electron beam radiation with the dose of 60kGy, and depositing an aluminum (Al) plated metal deposition layer with the thickness of 42nm on the resin substrate by vacuum vapor deposition, wherein the structure is CPE/Al (s/m).

Comparative example 6

To obtain a coating liquid necessary for laminating a film, materials such as PAA, PVA, TMOS and the like were dissolved and mixed in the same procedure as in example 1 to obtain a solution (II).

In order to obtain a laminated film, the solution (II) is uniformly coated on the surface of a BOPP base film with the thickness of 18 mu m by a wire bar coater, and after drying, an aluminized (Al) metal deposition layer with the thickness of 42nm is deposited on the solution by a vacuum vapor deposition layer to obtain the laminated film (I) with the structure of CPP/barrier primer coating/Al (s/p/m), wherein the thickness of the barrier primer coating is about 0.9 mu m.

Comparative example 7

In order to obtain a laminated film, the solution (II) is uniformly coated on the surface of a casting polypropylene (CPP) base film with the thickness of 25 mu m by a wire bar coater, after drying, the solution is irradiated by electron beam radiation with the irradiation dose of 60kGy, and an aluminized (Al) metal deposition layer with the thickness of 42nm is deposited on the solution by vacuum gas phase deposition to obtain the laminated film (I) with the structure of CPP/barrier primer coating/Al (s/p/m), wherein the thickness of the barrier primer coating is about 2.4 mu m.

Taking 50g of the obtained laminated film, mixing and extruding the film by a double-screw extruder according to the test method (8), taking an extruded sample, flattening the sample by a hot press, cutting the sample into a sample strip, testing the tensile property, and recording the yield strength and the elongation at break of the sample strip.

Comparative example 8

To obtain a coating liquid necessary for laminating a film, materials of PAA, PVA, TMOS and the like were dissolved and mixed to obtain a solution (II) according to the same procedure as in example 1.

In order to obtain a laminated film, the solution (II) is uniformly coated on the surface of a Casting Polyethylene (CPE) base film with the thickness of 40 mu m by a wire bar coater, after drying, the solution (II) is irradiated by electron beam with the irradiation dose of 60kGy, and an aluminized (Al) metal deposition layer with the thickness of 42nm is deposited on the solution (II) by vacuum gas phase deposition to obtain the laminated film (I) with the structure of CPE/barrier primer coating/Al (s/p/m), wherein the thickness of the barrier primer coating is about 2.4 mu m.

Comparative example 9

After 50g of the CPP base film which is not coated and aluminized is irradiated by electron beam with the irradiation dose of 60kGy, the sample is pressed and flattened by a hot press and cut into a sample strip according to the test method (8) after the mixed extrusion by a double-screw extruder, the tensile property is tested, and the yield strength and the elongation at break of the sample strip are recorded.

Comparative example 10

Taking 50g of CPE base film which is not coated and aluminized, irradiating by electron beam with the irradiation dose of 60kGy, mixing and extruding by a double-screw extruder according to a test method (8), taking an extruded sample, flattening by a hot press, cutting into a sample strip, testing the tensile property, and recording the yield strength and the elongation at break of the sample strip.

The obtained laminated film samples prepared in examples 1 to 6 and comparative examples 1 to 6 were tested according to the test methods (1) to (7), and the technical solutions (structures, formulations, and radiation doses) of examples 1 to 6 and comparative examples 1 to 6 are listed in table 1, and the test results are listed in table 2.

The tensile specimens obtained by the methods of examples 7 and 8 and comparative examples 7 to 10 were subjected to the test according to test method (8), and the results are shown in Table 3.

[ Table 1]

[ Table 2]

[ Table 3]

From the comparison of the barrier properties of the laminated films obtained in the above examples and comparative examples, it can be seen that the laminated film having the structure of the polyolefin resin substrate/the barrier primer coating/the aluminum metal deposition layer (s/p/m) of the present invention has excellent oxygen barrier properties, water vapor barrier properties, and simultaneously has high peel strength of the metal aluminum layer.

As shown in Table 2, it can be seen from the comparison of examples 1 to 6 with comparative examples 3 to 5 that the barrier primer coat can significantly reduce the oxygen transmission rate of the obtained laminated film. Meanwhile, the added barrier primer coating can obviously improve the bonding strength between the aluminum metal deposition layer and the resin substrate, and the obtained aluminum metal deposition layer has less perforation defects.

As shown in table 2, it can be seen from the comparison of example 2 with comparative examples 1 and 4 that the polymer containing carboxyl groups in the barrier primer layer can significantly improve the adhesive strength between the aluminum metal deposition layer and the resin substrate, and thus the obtained aluminum metal deposition layer has fewer perforation defects and the obtained laminate film has a lower oxygen transmission rate.

As shown in table 2, from the comparison of example 4 with comparative example 2, it can be seen that when the barrier primer coating is applied to the surface of the aluminum metal deposition layer, the adhesion strength between the barrier coating and the EAA film for heat sealing is low, which is not favorable for compounding the subsequent polyolefin layer material on the laminated film. Meanwhile, because the bonding strength between the aluminum layer and the polyolefin is low, more defects are introduced into the metal deposition layer in the aluminum plating process and the subsequent coating process.

As shown in table 2, from the comparison of examples 1 and 2 with comparative example 6, it can be seen that when a polymer containing carboxyl groups is added to the barrier primer, the gel fraction in the barrier primer is in a significant positive correlation with the electron beam radiation dose, and when the barrier primer is subjected to a higher electron beam radiation dose, the barrier primer has a higher gel fraction, exhibiting a better appearance after water immersion and lower oxygen and water vapor transmission rates. Compared with the comparative example 1, the results show that when no carboxyl-containing polymer is added into the blocking priming coating, the blocking priming coating is insensitive to electron beam radiation, and the gel rate, the appearance after water immersion, and the oxygen and water vapor blocking performance of the blocking priming coating are not obviously improved by the electron beam radiation, so that the carboxyl-containing polymer is a main compound which is crosslinked under the action of an electron beam.

As shown in table 3, it can be seen from the comparison between examples 7 and 8 and comparative examples 9 and 10 that when the barrier primer coating is thin, even though re-mixing and extrusion are performed, the obtained re-formed material has similar yield strength and elongation at break to the original base material, which indicates that the additional barrier primer coating and aluminum metal deposition layer do not have significant influence on the mechanical properties of the raw material, and the obtained laminated film can still obtain a product similar to the original base material by mixing and post-forming, and has good recyclability.

As shown in table 3, from the comparison of examples 7 and 8 with comparative examples 7 and 8, and comparative examples 7 and 8 with comparative examples 9 and 10, it can be seen that when the barrier primer coating is thicker, the remixed, extruded material produces a greater difference in mechanical properties, particularly a significant decrease in elongation at break, than the uncoated or thinner coated resin substrate, indicating that in such a case, when the additional barrier primer coating material is too much, the resulting laminated film is not suitable for recycling secondary molding processing.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A gas-and water-blocking laminated film, comprising:

a polyolefin or olefin copolymer resin substrate based on ethylene or propylene monomers;

a barrier primer coating layer formed on one or both surfaces of the resin substrate;

an aluminum metal deposition layer formed on the barrier primer coating;

wherein the barrier primer coating is formed by coating a coating liquid, drying the coating liquid and curing and crosslinking through electron beam radiation; the coating liquid includes:

selected from Si (OR)¹)₄… (1) or a hydrolysate thereof, wherein R is¹Is one of methyl or ethyl;

a carboxyl group-containing polymer A;

a hydroxyl group-containing polymer B;

the thickness of the barrier primer coating is not more than 1000 nm;

the thickness of the aluminum metal deposition layer is 1 nm-100 nm.

2. The gas-and water-blocking laminated film according to claim 1, wherein the coating liquid is irradiated with an electron beam of 150keV beam at an irradiation dose of 25kGy to 60kGy (based on the total weight of the barrier primer coating).

3. The gas and water barrier laminated film according to claim 1, wherein the gas and water barrier laminated film has an Oxygen Transmission Rate (OTR) of less than 1 ml/(m) in an atmosphere of 23 ℃ and 50% relative humidity²Day atm), a Water Vapor Transmission Rate (WVTR) of less than 1 g/(m) at 37.8 ℃ and 90% RH²Day atm), peel strength of ethylene-acrylic acid copolymer (EAA) at 23 ℃ and 54% relative humidity not less than 1.6N/15 mm.

4. The gas and water barrier laminated film according to claim 1, wherein the polymer B is partially or completely alcoholyzed polyvinyl alcohol or a copolymer of ethylene with vinyl alcohol and a vinyl alcohol ester.

5. A gas-and water-blocking laminated film according to any one of claims 1 to 4, wherein the resin substrate is selected from biaxially oriented polypropylene (BOPP) or cast polypropylene (CPP) or Cast Polyethylene (CPE).

6. A method for preparing a gas-barrier water-blocking laminated film is characterized by comprising the following steps:

a step (1) of coating and drying a coating liquid on one or both surfaces of a polyolefin or olefin copolymer resin substrate based on an ethylene or propylene monomer to obtain a barrier primer coating;

the coating liquid includes: selected from Si (OR)¹)₄… (1) or a hydrolysate thereof, wherein R is¹Is one of methyl or ethyl;

a carboxyl group-containing polymer A;

a hydroxyl group-containing polymer B;

step (2), curing and crosslinking the barrier primer coating by electron beam radiation;

and (3) depositing a layer of metal aluminum on the surface of the barrier priming coating to form an aluminum metal deposition layer, wherein the thickness of the aluminum metal deposition layer is 1-100 nm.

7. The production method according to claim 6, wherein in the step (2), the coating liquid is irradiated with an electron beam of 150keV beam at a dose of 25 to 60kGy (based on the total weight of the barrier primer coating).

8. The method of claim 6, wherein the resin substrate is subjected to corona treatment before the step (1).

9. The method according to claim 6, wherein in the step (3), the evaporation chamber is evacuated to 2 x 10^-5mbar, heating a heat source in the chamber to 1500 ℃, putting the aluminum wire in the evaporation chamber, gasifying the aluminum wire into aluminum steam, diffusing the aluminum steam into the evaporation chamber, and depositing the aluminum steam on the surface of the resin substrate introduced by the coating drum, wherein the rotating speed of the coating drum is 500-1000 m/min.

10. Use of the gas-and water-blocking laminated film according to any one of claims 1 to 5 or the gas-and water-blocking laminated film produced by the production method according to any one of claims 6 to 9 in packaging.