A rubbing-resistant transparent ultra-high barrier composite film and preparation method thereof

Abstract

The present invention relates to a rubbing-resistant transparent ultra-high barrier composite film and a preparation method thereof, wherein the rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer and a polypropylene film layer, wherein a barrier coating is provided between the polyamide film layer and the polypropylene film layer, wherein the barrier coating is composed of a polyvinyl alcohol layer and a polyurethane-modified epoxy resin layer, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded by an adhesive. The rubbing-resistant transparent ultra-high barrier composite film of the present invention has high transparency, good toughness and tensile strength, and is very suitable for packaging foods such as corn, canned fruit, and bamboo shoots, so that the food can maintain a shelf life of more than 180 days at room temperature after being sterilized at a high temperature of more than 121°C.

Description

Technical Field

[0001] The invention relates to the technical field of composite packaging films, in particular to a rubbing-resistant transparent ultra-high barrier composite film and a preparation method thereof. Background Art

[0002] The packaging film for room temperature food usually uses single-layer materials such as PE film. When the food needs to be cooked at high temperature, the PE packaging film is not resistant to high temperatures and cannot protect the food after high temperature treatment. At the same time, the mechanical strength of the film decreases after high temperature treatment, and it is difficult to prevent perforation of angular foods.

[0003] In the prior art, a packaging film suitable for high-temperature food is obtained by film compounding and modification. For example, Chinese invention patent application CN110626028A discloses a high-temperature resistant flame-retardant polyamide film and a preparation method thereof, wherein the high-temperature resistant flame-retardant polyamide film comprises a three-layer superimposed film structure, which is an upper surface layer, a core layer and a lower surface layer from the outside to the inside; the components of the upper surface layer and the lower surface layer include: 50-80 parts of polyamide, 10-20 parts of polyphenylene ether, and 5-10 parts of PET resin. 10 parts, toughening agent 5-10 parts, compatibilizer 2-5 parts, flame retardant 1-5 parts, antioxidant 0.1-1 parts, processing aid 0.1-1 parts, opening agent 0.4-1 parts, lubricant 0.1-0.5 parts; the core layer components include: polyamide 50-80 parts, polyphenylene ether 10-20 parts, PET resin 5-10 parts, toughening agent 5-10 parts, compatibilizer 2-5 parts, flame retardant 1-5 parts, antioxidant 0.1-1 parts, lubricant 0.5-2 parts, with high temperature resistance. The film uses a variety of processing aids to optimize the performance of polyamide, and there are safety hazards due to the introduction of polyphenylene ether.

[0004] At the same time, traditional high-barrier materials such as aluminum foil, aluminized film, or films containing coatings such as silicon oxide and aluminum oxide will be not resistant to rubbing. That is, after rubbing, the barrier layer will break, causing the barrier performance to decrease, thus affecting the shelf life of the food. Summary of the invention

[0005] The problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a rubbing-resistant transparent ultra-high barrier composite film and a preparation method thereof.

[0006] The rubbing-resistant transparent ultra-high barrier composite film of the present invention comprises a polyamide film layer and a polypropylene film layer, and a barrier coating is arranged between the polyamide film layer and the polypropylene film layer, and the barrier coating is composed of a polyvinyl alcohol layer and a polyurethane-modified epoxy resin layer. Polyvinyl alcohol has high water absorption and can pass water vapor, but is difficult to pass alcohol vapor, and is even more impermeable to organic solvent vapor, inert gas and hydrogen. The preferred density of the polyvinyl alcohol film is 0.8-0.9g / cm 3, with a refractive index of 1.2-1.3, it has a good barrier effect and can prevent oxygen and water vapor from entering the package and causing bacteria to grow in the package, thereby keeping the food fresh at room temperature.

[0007] The polyvinyl alcohol layer is preferably silicate-modified polyvinyl alcohol, which is prepared from a polyvinyl alcohol mixture, tetraethyl orthosilicate, a solvent, and an additive, for example: 50-60 parts by weight of polyvinyl alcohol mixture, 20-30 parts by weight of tetraethyl orthosilicate, 10-50 parts by weight of solvent (mixed with n-butanol and water in a volume ratio of 1:1-3:1), and 1-10 parts by weight of additive (using a hydrochloric acid aqueous solution with a concentration of 10-30%). The silicate is hydrolyzed to react with the polyvinyl alcohol to form a crosslink, so as to improve the barrier performance of the thin layer against organic matter.

[0008] The polyurethane modified epoxy resin layer in the present invention can effectively block water vapor, and cooperate with the polyvinyl alcohol layer to exert excellent barrier properties. The polyurethane modified epoxy resin layer uses thermosetting epoxy resin and polyurethane prepolymer under the action of an activator or catalyst to perform grafting, hanging and other modification actions, and cross-linking reaction to generate a composite material of epoxy resin and polyurethane, which has good impact resistance, water resistance and chemical resistance, and is flexible. The elasticity and elongation at break of the material are suitable for packaging foods such as corn, canned fruit, and bamboo shoots.

[0009] Preferably, the polyurethane-modified epoxy resin layer contains inorganic fillers, which are used to reduce the interfacial tension between the organic phase and the inorganic phase, and form an interpenetrating three-dimensional cross-linked network structure with the active groups of the polyurethane in the thin layer to improve the waterproof effect, have excellent physical strength, and significantly extend the service life of the film.

[0010] The specific plan is as follows:

[0011] A rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer and a polypropylene film layer, a barrier coating is arranged between the polyamide film layer and the polypropylene film layer, the barrier coating consists of a polyvinyl alcohol layer and a polyurethane-modified epoxy resin layer, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded by an adhesive.

[0012] Furthermore, the thickness of the rubbing-resistant transparent ultra-high barrier composite film is 10-500 microns.

[0013] Furthermore, the polyvinyl alcohol layer is adjacent to the polyamide film layer.

[0014] Furthermore, the polyamide film layer is a biaxially stretched polyamide film layer with a thickness of 5-300 microns.

[0015] Furthermore, the polypropylene film layer is a cast polypropylene film layer with a thickness of 1-200 microns.

[0016] Furthermore, the thickness of the polyvinyl alcohol layer is 1-20 um, and the polyvinyl alcohol layer is silicate-modified polyvinyl alcohol.

[0017] Furthermore, the polyurethane modified epoxy resin layer contains inorganic fillers, and the mass content of the inorganic fillers accounts for 1-5% of the total weight of the polyurethane modified epoxy resin layer.

[0018] Furthermore, the inorganic filler is any one of silicon oxide, barium sulfate, quantum dot material or mica powder.

[0019] Furthermore, the adhesive is a two-component high temperature resistant cooking adhesive.

[0020] A method for preparing the rubbing-resistant transparent ultra-high barrier composite film comprises the following steps:

[0021] Step 1: forming a polyvinyl alcohol layer on one side of the polyamide film layer, which is referred to as film 1, and forming a polyurethane modified epoxy resin layer on one side of the polypropylene film layer, which is referred to as film 2;

[0022] Step 2: Compounding, using an adhesive to bond the film 1 and the film 2 in step 1 by dry compounding or solvent-free compounding; wherein the amount of the adhesive is 3.5-4g / m 2 , during compounding, the polyvinyl alcohol layer and the polyurethane modified epoxy resin layer are bonded together by an adhesive;

[0023] Step 3: Curing, placing the composite film at 50-55° C. for 60-80 hours in a closed space to obtain the rubbing-resistant transparent ultra-high barrier composite film.

[0024] Beneficial effects: The rubbing-resistant transparent ultra-high barrier composite film of the present invention has high transparency, which is convenient for directly observing the state of food; it has excellent oxygen barrier properties after boiling and high-temperature treatment, which can prevent food from spoiling; at the same time, it has good toughness and tensile strength, and is very suitable for packaging foods such as corn, canned fruit, and bamboo shoots, so that the food can maintain a shelf life of more than 180 days at room temperature after high-temperature sterilization above 121°C. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with the embodiments. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in the art or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0026] Performance test: Oxygen permeability: tested according to ASTM F1927 standard.

[0027] Example 1

[0028] A rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer, a polyvinyl alcohol layer, an adhesive layer, a polyurethane-modified epoxy resin layer and a polypropylene film layer stacked in sequence, wherein the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer constitute a barrier coating, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded together by an adhesive to form an adhesive layer.

[0029] Specifically, the polyamide film layer is a biaxially stretched polyamide film layer with a thickness of 10 microns; the polypropylene film layer is a cast polypropylene film layer with a thickness of 20 microns; the polyvinyl alcohol layer has a thickness of 5um, and the polyurethane modified epoxy resin layer has a thickness of 5um.

[0030] The light transmittance of the rubbing-resistant transparent ultra-high barrier composite film exceeds 99%, the tensile strength (vertical / horizontal) is 92 / 108MPa, and the oxygen permeability is less than 1.0ml / m 2 *24h, water vapor transmission rate is 0.5-0.7ml / m 2 *24h.

[0031] Example 2

[0032] A rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer, a polyvinyl alcohol layer, an adhesive layer, a polyurethane-modified epoxy resin layer and a polypropylene film layer stacked in sequence, wherein the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer constitute a barrier coating, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded together by an adhesive to form an adhesive layer.

[0033] Specifically, the polyamide film layer is a biaxially oriented polyamide film layer with a thickness of 100 microns; the polypropylene film layer is a cast polypropylene film layer with a thickness of 50 microns; the polyvinyl alcohol layer is a silicate-modified polyvinyl alcohol with a thickness of 20um, and the polyurethane-modified epoxy resin layer has a thickness of 20um.

[0034] The rubbing-resistant transparent ultra-high barrier composite film has a light transmittance of more than 98%, a tensile strength of 105 / 110 MPa (vertical / horizontal), and an oxygen permeability of less than 1.0 ml / m 2 *24h, water vapor transmission rate is 0.5-0.6ml / m 2 *24h.

[0035] Example 3

[0036] A rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer, a polyvinyl alcohol layer, an adhesive layer, a polyurethane-modified epoxy resin layer and a polypropylene film layer stacked in sequence, wherein the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer constitute a barrier coating, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded together by an adhesive to form an adhesive layer.

[0037] Specifically, the polyamide film layer is a biaxially stretched polyamide film layer with a thickness of 200 microns; the polypropylene film layer is a cast polypropylene film layer with a thickness of 50 microns; the polyvinyl alcohol layer is a silicate-modified polyvinyl alcohol with a thickness of 15um, the polyurethane-modified epoxy resin layer has a thickness of 15um, and the polyurethane-modified epoxy resin layer is filled with 2% nano-silicon oxide.

[0038] The rubbing-resistant transparent ultra-high barrier composite film has a light transmittance of more than 98%, a tensile strength of 109 / 114 MPa (vertical / horizontal), and an oxygen permeability of less than 1.0 ml / m 2 *24h, water vapor transmission rate is 0.5-0.7ml / m 2 *24h.

[0039] Example 4

[0040] A rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer, a polyvinyl alcohol layer, an adhesive layer, a polyurethane-modified epoxy resin layer and a polypropylene film layer stacked in sequence, wherein the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer constitute a barrier coating, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded together by an adhesive to form an adhesive layer.

[0041] Specifically, the polyamide film layer is a biaxially stretched polyamide film layer with a thickness of 300 microns; the polypropylene film layer is a cast polypropylene film layer with a thickness of 200 microns; the polyvinyl alcohol layer is a silicate-modified polyvinyl alcohol with a thickness of 20um, the polyurethane-modified epoxy resin layer has a thickness of 20um, and the polyurethane-modified epoxy resin is filled with 2% mica powder.

[0042] The rubbing-resistant transparent ultra-high barrier composite film has a light transmittance of more than 98%, a tensile strength of 116 / 120 MPa (vertical / horizontal), and an oxygen permeability of less than 1.0 ml / m 2 *24h, water vapor transmission rate is 0.5-0.9ml / m 2 *24h.

[0043] Example 5

[0044] A rubbing-resistant transparent ultra-high barrier composite film comprises a polyamide film layer, a polyvinyl alcohol layer, an adhesive layer, a polyurethane-modified epoxy resin layer and a polypropylene film layer stacked in sequence, wherein the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer constitute a barrier coating, and the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded together by an adhesive to form an adhesive layer.

[0045] Specifically, the polyamide film layer is a biaxially stretched polyamide film layer with a thickness of 120 microns; the polypropylene film layer is a cast polypropylene film layer with a thickness of 30 microns; the polyvinyl alcohol layer has a thickness of 10um, and the polyurethane modified epoxy resin layer has a thickness of 10um, and the polyurethane modified epoxy resin is filled with 2% green quantum dot material.

[0046] The light transmittance of the rubbing-resistant transparent ultra-high barrier composite film exceeds 98%, the tensile strength (vertical / horizontal) is 105 / 118MPa, and the oxygen permeability is less than 1.0ml / m 2 *24h, water vapor transmission rate is 0.5-0.6ml / m 2 *24h.

[0047] Example 6

[0048] The film in Example 3 was boiled at 100°C for 30 minutes and then tested. The tensile strength (longitudinal / transverse) was 93 / 98 MPa and the oxygen permeability was less than 1.1 ml / m 2 *24h, water vapor transmission rate is 0.7-1.0ml / m 2 *24h.

[0049] Example 7

[0050] The film in Example 4 was boiled at 120°C for 30 minutes and then tested. The tensile strength (longitudinal / transverse) was 101 / 105 MPa and the oxygen permeability was less than 1.1 ml / m 2 *24h, water vapor transmission rate is 0.7-1.0ml / m 2 *24h.

[0051] Example 8

[0052] The preparation of a rubbing-resistant transparent ultra-high barrier composite film comprises the following steps:

[0053] Step 1: forming a polyvinyl alcohol layer on one side of the polyamide film layer, which is referred to as film 1, and forming a polyurethane modified epoxy resin layer on one side of the polypropylene film layer, which is referred to as film 2;

[0054] Step 2: Compounding, using an adhesive to bond the film 1 and the film 2 in step 1 by dry compounding or solvent-free compounding; wherein the amount of the adhesive is 3.5-4g / m 2, during compounding, the polyvinyl alcohol layer and the polyurethane modified epoxy resin layer are bonded together by an adhesive;

[0055] Step 3: Curing, placing the composite film at 50-55° C. for 60-80 hours in a closed space to obtain the rubbing-resistant transparent ultra-high barrier composite film.

[0056] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A rubbing-resistant transparent ultra-high barrier composite film, characterized in that: The rub-resistant transparent ultra-high barrier composite film comprises a polyamide film layer and a polypropylene film layer, a barrier coating is arranged between the polyamide film layer and the polypropylene film layer, the barrier coating consists of a polyvinyl alcohol layer and a polyurethane-modified epoxy resin layer, the polyvinyl alcohol layer and the polyurethane-modified epoxy resin layer are bonded by an adhesive; the thickness of the polyvinyl alcohol layer is 1-20 μm, and the polyvinyl alcohol layer is silicate-modified polyvinyl alcohol; the polyurethane-modified epoxy resin layer contains an inorganic filler, the mass content of the inorganic filler accounts for 1-5% of the total weight of the polyurethane-modified epoxy resin layer, and the inorganic filler is any one of silicon oxide, barium sulfate or mica powder.

2. The rubbing-resistant transparent ultra-high barrier composite film according to claim 1, characterized in that: The thickness of the rubbing-resistant transparent ultra-high barrier composite film is 10-500 microns.

3. The rubbing-resistant transparent ultra-high barrier composite film according to claim 1, characterized in that: The polyvinyl alcohol layer is adjacent to the polyamide film layer.

4. The rubbing-resistant transparent ultra-high barrier composite film according to any one of claims 1 to 3, characterized in that: The polyamide film layer is a biaxially stretched polyamide film layer with a thickness of 5-300 microns.

5. The rubbing-resistant transparent ultra-high barrier composite film according to any one of claims 1 to 3, characterized in that: The polypropylene film layer is a cast polypropylene film layer with a thickness of 1-200 microns.

6. The rubbing-resistant transparent ultra-high barrier composite film according to any one of claims 1 to 3, characterized in that: The adhesive is a two-component high temperature resistant cooking adhesive.

7. The method for preparing the rubbing-resistant transparent ultra-high barrier composite film according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: forming a polyvinyl alcohol layer on one side of the polyamide film layer, which is referred to as film 1, and forming a polyurethane modified epoxy resin layer on one side of the polypropylene film layer, which is referred to as film 2; Step 2: Compounding, using an adhesive to bond the film 1 and the film 2 in step 1 by dry compounding or solvent-free compounding; wherein the amount of the adhesive is 3.5-4g / m 2 , during compounding, the polyvinyl alcohol layer and the polyurethane modified epoxy resin layer are bonded together by an adhesive; Step 3: Curing, placing the composite film at 50-55° C. for 60-80 hours in a closed space to obtain the rubbing-resistant transparent ultra-high barrier composite film.