A process for the preparation of polyethylene composites

Abstract

The application discloses a processing method for preparing polyethylene composite material, which comprises a gravure printing process, a first-time composite process and a second-time composite process. In the process of preparing the polyethylene composite material, the longitudinal-stretching polyethylene film is first combined with the aluminized polyethylene film in the first-time composite process, and then combined with the polyethylene film in the second-time composite process, so that the aluminized polyethylene film is made into the intermediate barrier layer of the polyethylene composite material. The polyethylene composite material obtained by combining the aluminized polyethylene film and the polyethylene film has excellent gas-liquid barrier property and high barrier property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyethylene compounding, in particular to a processing method for preparing a single polyethylene material composite film. BACKGROUND

[0002] Soft packaging refers to packaging in which the shape of the container can change after filling or removing the contents. Various bags, boxes, sleeves, and packages made of plastic film and their composites are all soft packaging and can be widely used in food, cosmetic, and pharmaceutical packaging fields.

[0003] Traditional soft packaging film preparation and processing methods are usually composite processing of multiple different material films. Polyethylene film and polyester film are used as base materials, and PE, PP, or BOPP is used for compounding to obtain a packaging composite film structure. Although the packaging composite film prepared by traditional soft packaging film can protect the packaging contents, prevent pollutants and infiltration, and prevent the packaging contents from seeping out. However, the packaging composite film processed by the traditional preparation method has insufficient barrier properties, poor gas barrier properties, high oxygen transmission, and insufficient heat seal strength, which cannot effectively prevent the penetration of external water vapor and gas. Some gases can penetrate the packaging composite film into the packaging bag, causing bacterial reproduction and causing the contents of the packaging bag to deteriorate. For some packaging content products that are sensitive to humidity, the moisture resistance of the packaging composite film processed by the traditional preparation method cannot meet the packaging requirements of the products. Moreover, the packaging composite film processed by the traditional preparation method is composed of multiple layers of different material structures. When recycling the packaging composite film, different material layers need to be peeled off, increasing the complexity of the recycling process and being not conducive to the recycling of the packaging composite film.

[0004] In the prior art, in order to increase the barrier property of the packaging composite film, a layer of polyvinylidene chloride (PVDC) coating film is compounded during compounding and preparation. Although it can achieve the effect of blocking oxygen and water vapor, this polyvinylidene chloride (PVDC) coating film requires special equipment and cannot be melted and granulated for recycling. The waste produces hydrogen chloride, dioxin, and other substances that are toxic and harmful to humans and the surrounding environment when incinerated, not only causing damage to the environment, but also posing a threat to human life and health. SUMMARY

[0005] The technical problem solved by the present application is to provide a processing method for preparing polyethylene composite material, which is suitable for using longitudinal stretching polyethylene film, high moisture resistance aluminized polyethylene film, polyethylene film for compounding, compounding the longitudinal stretching polyethylene film and the high moisture resistance aluminized polyethylene film for the first time, and then compounding the high oxygen resistance polyethylene film for the second time, so as to make the high moisture resistance aluminized polyethylene film into the intermediate barrier layer of the polyethylene composite material, and the polyethylene composite material obtained by compounding the high moisture resistance aluminized polyethylene film and the high oxygen resistance polyethylene film has excellent gas-liquid barrier property, high barrier property, excellent heat sealing performance, moderate friction coefficient, no adhesion, no slip during cutting, and is very suitable for the processing method on the high-speed packaging production line.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] The present application provides a processing method for preparing polyethylene composite material, which comprises the processing method for preparing the polyethylene composite material, wherein the polyethylene composite material is prepared by compounding longitudinal stretching polyethylene film, polyurethane ink layer, first layer of double-component polyurethane adhesive, high moisture resistance aluminized polyethylene film, second layer of double-component polyurethane adhesive, and high oxygen resistance polyethylene film, and the processing method specifically comprises the following steps:

[0008] Step S1) gravure printing process: the prepared 25μm thick longitudinal stretching polyethylene film is loaded on the first feeding shaft of the gravure printing machine, the 25μm thick longitudinal stretching polyethylene film is sent to each printing color unit through the first feeding shaft of the printing machine, the longitudinal stretching polyethylene film is used as the base material for gravure printing, a layer of polyurethane ink layer is printed on the surface of the longitudinal stretching polyethylene film, the ink viscosity is controlled at 13-17 viscosity / Pa.s, the tension required for the first unwinding roller of the printing machine to unwind the longitudinal stretching polyethylene film is 100N, and the winding tension after printing is 120N;

[0009] Step S2) First composite processing: the 25μm thick longitudinal stretching polyethylene film printed in step 1 is loaded into the second spool end, the tension required for the second spool to feed the 25μm thick longitudinal stretching polyethylene film is 120N, the prepared 40μm thick high-wet-resistance aluminum-plated polyethylene film is loaded into the third spool end, the tension required for the third spool to feed the 40μm thick high-wet-resistance aluminum-plated polyethylene film is 140N, the 25μm thick longitudinal stretching polyethylene film is sent into the first glue coating system through the second spool end, the first glue coating roller of the first glue coating system applies the first layer of double-component polyurethane adhesive to the inner surface of the processing surface of the 25μm thick longitudinal stretching polyethylene film, the 25μm thick longitudinal stretching polyethylene film is dried in the oven to volatilize the organic solvent in the first layer of double-component polyurethane adhesive, the 25μm thick longitudinal stretching polyethylene film enters the three drying channels in the oven for drying, the temperatures of the three drying channels are 50℃, 60℃ and 70℃ respectively, the processing surfaces of the longitudinal stretching polyethylene film and the high-wet-resistance aluminum-plated polyethylene film are hot-pressed to form a semi-finished composite film, the pressure required for the hot-pressing process of the hot-pressing guide roller is 0.35Mpa, the composite speed is 90M / min, the gluing mesh of the first glue coating roller is 110*75 concave screen mesh roller, the gluing amount is 3.2-3.5g / ㎡, and the tension required for the winding of the semi-finished composite film is 200N.

[0010] Step S3) Second composite processing: the semi-finished composite film after the first composite processing is loaded into the fourth spool end, the tension required for the fourth spool to feed the semi-finished composite film is 160N, the prepared 70μm thick high-oxygen-resistance polyethylene film is loaded into the fifth spool end, the tension required for the fifth spool to feed the 70μm thick high-oxygen-resistance polyethylene film is 140N, the semi-finished composite film is sent into the second glue coating system through the fourth spool, the second glue coating roller of the second glue coating system applies the second layer of double-component polyurethane adhesive to the inner surface of the processing surface of the 40μm thick high-wet-resistance aluminum-plated polyethylene film, the semi-finished composite film is dried in the oven to volatilize the organic solvent in the second layer of double-component polyurethane adhesive, the semi-finished composite film enters the three drying channels in the oven for drying, the temperatures of the three drying channels are 50℃, 60℃ and 70℃ respectively, the inner surfaces of the processing surfaces of the semi-finished composite film and the high-oxygen-resistance polyethylene film are hot-pressed to form a polyethylene composite material, the pressure required for the hot-pressing process of the hot-pressing guide roller of the polyethylene composite material is 0.35Mpa, the composite speed is 90M / min, the gluing mesh of the second glue coating roller is 110*75 concave screen mesh roller, the gluing amount is 3.2-3.5g / ㎡, and the tension required for the winding of the polyethylene composite material is 240N.

[0011] For further improvement of the above technical scheme, the type of the first layer two-component polyurethane adhesive and the second layer two-component polyurethane adhesive used in steps S2) and S3) is a two-component polyurethane adhesive with a type of "XH-66F / XH-K75", and the ratio of the two-component polyurethane adhesive is: main agent XH-66F: curing agent XH-K75: ethyl acetate solvent = 20:3.8:26.

[0012] For further improvement of the above technical scheme, the longitudinal stretch polyethylene film in step S1) is made of a heat sealing layer, an intermediate layer and a corona layer, the heat sealing layer accounts for 30%, the intermediate layer accounts for 40%, and the corona layer accounts for 30%; the heat sealing layer is composed of 20% medium density metallocene polyethylene and 80% low pressure high density polyethylene resin; the intermediate layer is composed of 100% metallocene polyethylene; and the corona layer is composed of 29% medium density metallocene polyethylene, 70% low pressure high density metallocene polyethylene, 0.5% opening agent and 0.5% slip agent.

[0013] For further improvement of the above technical scheme, the longitudinal stretch polyethylene film in step S1) is prepared by the following processing steps:

[0014] Step S11) The components are weighed and mixed according to the percentage corresponding to each layer of the longitudinal stretch polyethylene film, and the mixture of each layer is added to the three barrels of the corresponding WH film blowing machine to prepare the mixture of the heat sealing layer, the mixture of the intermediate layer and the mixture of the corona layer, which are plasticized into molten materials by high temperature heating below the three barrels of the WH film blowing machine, and the temperature of the high temperature heating is 180-250℃;

[0015] Step S12) The molten material is extruded into a molten film through the three-layer co-extrusion film blowing die of the WH film blowing machine, the extrusion speed is 550-600 Kg / h, and then the film bubble is formed by blowing the molten film through the WH film blowing machine, and then cooled;

[0016] Step S13) The cooled and shaped film is flattened, and the film enters the MDO stretching equipment of the WH film blowing machine under the action of the rotating traction roller for stretching process, the temperature during longitudinal stretching is 90-100℃, the stretching ratio of the film is 5, and after stretching, the film is heat set at a temperature of 150℃;

[0017] Step S14) The stretched film is cut and rolled after corona treatment, and the longitudinal stretch polyethylene film is obtained.

[0018] For further improvement of the above technical scheme, the high-barrier wet aluminum-coated polyethylene film in step S2) is made by high-temperature fusion of a first layer A particle layer, a second layer B particle layer, and a third layer C particle layer, the first layer A particle layer accounts for 30%, the second layer B particle layer accounts for 40%, and the third layer C particle layer accounts for 30%, wherein the first layer A particle layer is composed of 100% linear medium-density polyethylene resin; the second layer B particle layer is composed of 80% low-pressure high-density polyethylene resin and 20% high-pressure low-density polyethylene resin; and the third layer C particle layer is composed of 80% medium-density metallocene polyethylene, 19% high-pressure low-density polyethylene resin, 0.5% opening agent, and 0.5% slip agent.

[0019] For further improvement of the above technical scheme, the high-barrier wet aluminum-coated polyethylene film in step S2) is prepared by the following processing steps:

[0020] Step S21) The components are weighed according to the percentage corresponding to each layer of the high-barrier wet aluminum-coated polyethylene film and then mixed, and then added to the three barrels of the extruder respectively to prepare the mixed material of the first layer A particle layer, the mixed material of the second layer B particle layer, and the mixed material of the third layer C particle layer.

[0021] Step S22) The mixed materials in the three barrels of step S21) are subjected to high-temperature melting by the high-temperature melting device of the extruder to form a tube blank, and the temperature required for high-temperature melting is 180-300℃.

[0022] Step S23) After stretching the tube blank, it is extruded from the center of the extruder die and compressed air is supplied to blow the tube blank into a film bubble, and at the same time, the film bubble is cooled and shaped by an air ring to obtain a film.

[0023] Step S24) The film prepared in step S23) is sent into an aluminum-coating machine, and the film is subjected to double-corona vacuum evaporation to obtain a high-barrier wet polyethylene film.

[0024] For further improvement of the above technical scheme, the water vapor transmission rate of the high-barrier wet aluminum-coated polyethylene film prepared by steps S21)-S24) is 0.5-0.8 g / (m 2 ·24h).

[0025] For further improvement of the above technical scheme, the high oxygen barrier polyethylene film in step S3) is prepared by seven-layer co-extrusion of a polyamide layer, a first low-density polyethylene layer, a first adhesive layer, an ethylene-vinyl alcohol copolymer layer, a second adhesive layer, a second low-density polyethylene layer, and a polyethylene layer, wherein the polyamide layer accounts for 25%, the first low-density polyethylene layer accounts for 15%, the first adhesive layer accounts for 5%, the ethylene-vinyl alcohol copolymer layer accounts for 10%, the second adhesive layer accounts for 5%, the second low-density polyethylene layer accounts for 15%, and the polyethylene layer accounts for 25%.

[0026] For further improvement of the above technical scheme, the polyamide layer of the high oxygen barrier polyethylene film in step S3) is composed of 100% polyamide; the first low-density polyethylene layer is composed of 72% linear low-density polyethylene and 28% high-pressure low-density polyethylene; the first adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low-density polyethylene; the ethylene-vinyl alcohol copolymer layer is composed of 26% polymerized vinyl acetate and 74% polymerized ethylene; the second adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low-density polyethylene; the second low-density polyethylene layer is composed of 72% linear low-density polyethylene and 28% high-pressure low-density polyethylene; and the polyethylene layer is composed of 37% metallocene polyethylene, 30% linear low-density polyethylene, 32% high-pressure low-density polyethylene, 0.5% opening agent, and 0.5% slip agent.

[0027] For further improvement of the above technical scheme, the high oxygen barrier polyethylene film in step S3) is prepared by the following processing steps:

[0028] Step S31) The components are weighed according to the percentage corresponding to each layer in the high oxygen barrier polyethylene film, and mixed. The mixture obtained by mixing the layers is added to the seven barrels of the extruder.

[0029] Step S32) The mixture in step S1 is added to the seven barrels of the extruder, and heated and melted into a melt by the high-temperature heating and melting device of the extruder. The temperature of high-temperature melting is 200-300°C. Seven layers of polyamide layer, first low-density polyethylene layer, first adhesive layer, ethylene-vinyl alcohol copolymer layer, second adhesive layer, second low-density polyethylene layer, and polyethylene layer are respectively prepared. Then, the seven layers are co-extruded by the extruder, and then distributed by the flow channel distributor and converged and heated in the T-shaped die.

[0030] Step S33) The resin film flowing out after converging and heating in the T-shaped die is cooled and shaped by the cooling roller to obtain the high oxygen barrier polyethylene film. The density of the obtained high oxygen barrier polyethylene film is 1.12 g / cm 3 The oxygen transmission rate of the high oxygen barrier polyethylene film is ≤5.0 cm 3The friction coefficient of the high-oxygen-barrier polyethylene film is 0.44-0.48, the temperature required for heating of the T-shaped die is 250-300 DEG C, and the cooling temperature is 15-25 DEG C.

[0031] Step S34) trimming the high-oxygen-barrier polyethylene film and winding by a winding machine.

[0032] Compared with the prior art, the scheme of the present application has at least the following beneficial effects:

[0033] (1) The processing method for preparing the polyethylene composite material of the present application comprises gravure printing treatment, first-time composite treatment, and second-time composite treatment. The present application uses a longitudinally stretched polyethylene film as a base material for gravure printing. The side of the longitudinally stretched polyethylene film coated with a first layer of bi-component polyurethane adhesive is used to form a semi-finished composite film. The longitudinally stretched polyethylene film and the high-wetness-barrier aluminum-plated polyethylene film are subjected to hot-pressing composite using a hot-pressing composite guide roller. The longitudinally stretched polyethylene film and the high-wetness-barrier aluminum-plated polyethylene film subjected to the first-time composite are coated with adhesive and subjected to second-time composite with a polyethylene film to form a polyethylene composite material. In the process of preparing the polyethylene composite material, the longitudinally stretched polyethylene film and the high-wetness-barrier aluminum-plated polyethylene film are subjected to first-time composite, and then the high-oxygen-barrier polyethylene film is subjected to second-time composite. The 25-micron-thick longitudinally stretched polyethylene film coated with adhesive is dried in an oven to volatilize the organic solvent in the bi-component polyurethane adhesive, so as to realize solvent-free composite. The polyethylene composite material is prepared by using the composite method. When recycled, the separation of the film layers from each other is relatively easy. Each film layer can be recycled for reuse, which is beneficial to the environment and saves resources. The high-wetness-barrier aluminum-plated polyethylene film is used as the intermediate barrier layer of the polyethylene composite material. The polyethylene composite material obtained by using the high-wetness-barrier aluminum-plated polyethylene film and the high-oxygen-barrier polyethylene film has excellent gas and liquid barrier properties, high barrier property, excellent heat-sealing performance, moderate friction coefficient, and no sticking, slipping, or the like when cut, and is very suitable for use on a high-speed packaging production line. The longitudinally stretched polyethylene film, the high-wetness-barrier aluminum-plated polyethylene film, and the high-oxygen-barrier polyethylene film used for the composite are all multilayer composite films made of polyethylene as a single material. When recycled, the different plastics do not need to be peeled off, which greatly reduces the complexity of the process and is beneficial to recycling.

[0034] (2) The high moisture-resistant aluminum-plated polyethylene film of the present application is made by high-temperature fusion of a first layer A particle layer, a second layer B particle layer, and a third layer C particle layer, the first layer A particle layer accounts for 30%, the second layer B particle layer accounts for 40%, and the third layer C particle layer accounts for 30%, wherein the first layer A particle layer is composed of 100% linear medium-density polyethylene resin; the second layer B particle layer is composed of 80-85% low-pressure high-density polyethylene resin and 10-25% high-pressure low-density polyethylene resin; and the third layer C particle layer is composed of 80-81% medium-density metallocene polyethylene, 14-25% high-pressure low-density polyethylene resin, 0.5-2% opening agent, and 0.5-2% slip agent. The components of each layer structure of the high moisture-resistant aluminum-plated polyethylene film are mixed and then added to three barrels of an extruder, respectively, to obtain the mixed material of the first layer A particle layer, the mixed material of the second layer B particle layer, and the mixed material of the third layer C particle layer. The mixed materials in the three barrels are subjected to high-temperature melting by a high-temperature heating and melting device of the extruder to form a tube blank, which is then stretched, extruded from the center of the extruder die, and compressed with air to blow the tube blank into a film bubble. At the same time, the film bubble is cooled and shaped by an air ring to obtain a film. The film obtained in step S23 is sent into an aluminum plating machine, and the film is subjected to double corona vacuum evaporation plating to obtain a high moisture-resistant polyethylene film. The water vapor transmission rate of the high moisture-resistant aluminum-plated polyethylene film prepared by the preparation steps is 0.5-0.8 g / (m2·24h). Compared with ordinary linear low-density polyethylene, the high moisture-resistant aluminum-plated polyethylene film prepared by the present application can greatly improve the barrier property of the polyethylene composite material after being compounded with the polyethylene composite material.

[0035] (3) The high-oxygen-barrier polyethylene film of the present application is formed by co-extrusion of seven layers of a polyamide layer, a first low-density polyethylene layer, a first adhesive layer, an ethylene-vinyl alcohol copolymer layer, a second adhesive layer, a second low-density polyethylene layer, and a polyethylene layer, with the polyamide layer accounting for 25%, the first low-density polyethylene layer accounting for 15%, the first adhesive layer accounting for 5%, the ethylene-vinyl alcohol copolymer layer accounting for 10%, the second adhesive layer accounting for 5%, the second low-density polyethylene layer accounting for 15%, and the polyethylene layer accounting for 25%. The polyamide layer of the high-oxygen-barrier polyethylene film is composed of 100% polyamide; the first low-density polyethylene layer is composed of 72% linear high-density polyethylene and 28% high-pressure high-density polyethylene; the first adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low-density polyethylene; the ethylene-vinyl alcohol copolymer layer is composed of 20-35% polymerized vinyl acetate and 74-76% polymerized ethylene; the second adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low-density polyethylene; the second low-density polyethylene layer is composed of 72% linear high-density polyethylene and 28% high-pressure low-density polyethylene; and the polyethylene layer is composed of 30-40% metallocene polyethylene, 30-32% linear low-density polyethylene, 30-34% high-pressure low-density polyethylene, 0.5-2% opening agent, and 0.5-2% slip agent. The layers are co-extruded by an extruder, then flow through a flow channel distributor, and then converge and heat in a T-shaped die. The resin flowing out of the T-shaped die after convergence and heating is formed into a film by a cooling roller, and the film is then cooled and shaped to obtain the high-oxygen-barrier polyethylene film. The density of the obtained high-oxygen-barrier polyethylene film is 1.12 g / cm 3 , the oxygen transmission rate of the high-oxygen-barrier polyethylene film is ≤5.0 cm 3 / (m2·24h·0.1MPa), and the friction coefficient of the high-oxygen-barrier polyethylene film is 0.44-0.48. The high-oxygen-barrier polyethylene film prepared by the present application has extremely high barrier properties and excellent heat sealing performance. The friction coefficient of the high-oxygen-barrier polyethylene film is moderate, and the film will not stick or slip when cut, which is suitable for high-speed packaging production lines. BRIEF DESCRIPTION OF DRAWINGS

[0036] Fig. 1 The figure is a flowchart of the process of processing the polyethylene composite material of the present application;

[0037] Fig. 2 The figure is a structural diagram of the polyethylene composite material of the present application;

[0038] Fig. 3 The figure is a spectrum of the polyethylene composite material of the present application identifying the longitudinal stretch polyethylene film;

[0039] Fig. 4 The figure is a spectrum of the polyethylene composite material of the present application identifying the high-barrier-wet aluminum-plated polyethylene film;

[0040] Fig. 5 Spectrum of the polyethylene composite material of the present application for identifying the high-oxygen-barrier polyethylene film.

[0041] In the figure, the longitudinal stretch polyethylene film 1, the polyurethane ink layer 2, the first layer of the two-component polyurethane adhesive 3, the high-wetness-resistance aluminum-plated polyethylene film 4, the second layer of the two-component polyurethane adhesive 5, and the high-oxygen-barrier polyethylene film 6. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0043] As shown in Figs. 1-2 The present application provides a processing method for preparing a polyethylene composite material, which comprises the following steps:

[0044] Step S1) gravure printing process: the prepared 25μm-thick longitudinal stretch polyethylene film 1 is loaded on the first unwinding shaft of the gravure printing machine, the 25μm-thick longitudinal stretch polyethylene film 1 is sent to each printing color unit through the first unwinding shaft of the printing machine, the longitudinal stretch polyethylene film 1 is used as the base material to perform gravure printing, a layer of polyurethane ink layer 2 is printed on the surface of the longitudinal stretch polyethylene film 1, the viscosity of the ink is controlled at 13-17 viscosity / Pa.s, the tension required for the first unwinding roll of the printing machine to unwind the longitudinal stretch polyethylene film 1 is 100N, and the winding tension after printing is 120N;

[0045] Step S2) first composite processing: the 25μm thick longitudinal stretch polyethylene film 1 printed in step 1 is loaded into the second feed shaft end, the tension required for the second feed shaft to feed the 25μm thick longitudinal stretch polyethylene film 1 is 120N, the prepared 40μm thick high resistance wet aluminized polyethylene film 4 is loaded into the third feed shaft end, the tension required for the third feed shaft to feed the 40μm thick high resistance wet aluminized polyethylene film 4 is 140N, the 25μm thick longitudinal stretch polyethylene film 1 is sent into the first gluing system through the second feed shaft end, the first gluing roller of the first gluing system applies the first layer of double-component polyurethane adhesive 3 on the inner surface of the processing surface of the 25μm thick longitudinal stretch polyethylene film 1, the 25μm thick longitudinal stretch polyethylene film 1 after coating enters the oven for drying, and the organic solvent in the first layer of double-component polyurethane adhesive 3 is volatilized, the 25μm thick longitudinal stretch polyethylene film 1 enters the three ovens in the oven for drying, the temperatures of the three ovens are 50℃, 60℃ and 70℃ respectively, the longitudinal stretch polyethylene film 1 after drying through the three ovens is hot-pressed with the processing surface of the high resistance wet aluminized polyethylene film 4 to form a semi-finished composite film, the pressure required for the hot-pressing guide roller during hot-pressing is 0.35Mpa, the composite speed is 90M / min, the gluing mesh of the first gluing roller is 110*75 concave mesh, the gluing amount is 3.2-3.5g / ㎡, and the tension required for winding the semi-finished composite film is 200N;

[0046] Step S3) Second time composite processing: the first time composite semi-finished product composite film (25 μm thick longitudinal stretch polyethylene film 1 / 40 μm thick high resistance wet plated aluminum polyethylene film 4) is loaded into the fourth feed shaft end, and the fourth feed shaft requires a tension of 160 N for feeding the semi-finished product composite film. The prepared 70 μm thick high resistance oxygen polyethylene film 6 is loaded into the fifth feed shaft end, and the fifth feed shaft requires a tension of 140 N for feeding the 70 μm thick high resistance oxygen polyethylene film 6. The semi-finished product composite film (25 μm thick longitudinal stretch polyethylene film 1 / 40 μm thick high resistance wet plated aluminum polyethylene film 4) is fed into the second gluing system through the fourth feed shaft. The second gluing roller of the second gluing system applies the second layer of two-component polyurethane adhesive 5 to the treated surface of the 40 μm thick high resistance wet plated aluminum polyethylene film 4. The coated semi-finished product composite film (25 μm thick longitudinal stretch polyethylene film 1 / 40 μm thick high resistance wet plated aluminum polyethylene film 4) is dried in the oven to volatilize the organic solvent in the second layer of two-component polyurethane adhesive 5. The semi-finished product composite film enters the three ovens in the oven for drying. The temperatures of the three ovens are 50°C, 60°C, and 70°C, respectively. The semi-finished product composite film (25 μm thick longitudinal stretch polyethylene film 1 / 40 μm thick high resistance wet plated aluminum polyethylene film 4) is hot-pressed with the treated surface of the high resistance oxygen polyethylene film 6 to form a polyethylene composite material. The hot-pressing process of the polyethylene composite material hot-pressing guide roller requires a pressure of 0.35 Mpa, and the composite speed is 90 M / min. The second gluing roller has a gluing mesh of 110*75 concave mesh, a gluing amount of 3.2-3.5 g / ㎡, and a tension of 240 N required for winding the polyethylene composite material.

[0047] In the present application, the 25 μm thick longitudinal stretch polyethylene film 1 can be referred to as 25MDOPE, the 40 μm thick high resistance wet plated aluminum polyethylene film 4 can be referred to as 40VMPE, and the 70 μm thick high resistance oxygen polyethylene film 6 can be referred to as 70EVE.

[0048] The polyethylene composite material of the present application uses the longitudinally stretched polyethylene film 1 as the outer layer, uses the high-wet-resistance aluminum-plated polyethylene film 4 as the intermediate barrier layer of the polyethylene composite material, and uses the high-oxygen-resistance polyethylene film 6 as the inner layer of the polyethylene composite material. The polyethylene composite material obtained by compounding the high-wet-resistance aluminum-plated polyethylene film 4 and the high-oxygen-resistance polyethylene film 6 has excellent gas-liquid barrier property, high barrier property, excellent heat sealing performance, moderate friction coefficient, and will not produce adhesion, slip during cutting, and is very suitable for high-speed packaging production line. The multilayer composite film using polyethylene as a single material can meet the printing requirements, and has good barrier property, heat sealing performance and forming property.

[0049] In the process of preparing the polyethylene composite material, the first layer of the two-component polyurethane adhesive 3 and the second layer of the two-component polyurethane adhesive 5 used are two-component polyurethane adhesives with a model number of "XH-66F / XH-K75". The ratio of the two-component polyurethane adhesive is: main agent XH-66F: curing agent XH-K75: ethyl acetate solvent = 20:3.8:26. The working liquid concentration of the two-component polyurethane adhesive is 25-32%, and the viscosity of the two-component polyurethane adhesive is 15±2 seconds. The viscosity of the two-component polyurethane adhesive is measured using a 3# Zahn cup at a specific working liquid concentration at 25°C.

[0050] The longitudinally stretched polyethylene film 1 of the present application is prepared by using a heat sealing layer, an intermediate layer and a corona layer. The heat sealing layer accounts for 30%, the intermediate layer accounts for 40%, and the corona layer accounts for 30%. The heat sealing layer is composed of 20% medium density metallocene polyethylene and 80% low pressure high density polyethylene resin. The intermediate layer is composed of 100% metallocene polyethylene. The corona layer is composed of 29% medium density metallocene polyethylene, 70% low pressure high density metallocene polyethylene, 0.5% opening agent and 0.5% slip agent. In specific implementation, the longitudinally stretched polyethylene film 1 is prepared by using the following processing steps:

[0051] Step S11) The components are weighed and mixed according to the percentages corresponding to each layer of the longitudinally stretched polyethylene film 1, and the mixture obtained by mixing each layer is added to the three barrels of the corresponding WH film blowing machine to prepare the mixture of the heat sealing layer, the mixture of the intermediate layer and the mixture of the corona layer. The high temperature heating temperature is 180-250°C.

[0052] Step S12) The melt is extruded through a three-layer co-extrusion film blowing die of the WH film blowing machine to obtain a melt film, the extrusion speed is 550-600 Kg / h, the melt film is blown to form a film bubble through the WH film blowing machine, and then is cooled;

[0053] Step S13) The cooled and formed film is flattened, and the film enters the MDO stretching equipment of the WH film blowing machine under the action of the rotating traction roller to perform a stretching process, the temperature is 90-100 DEG C during longitudinal stretching, the stretching ratio of the film is 5, and the film is heat set at 150 DEG C after stretching;

[0054] Step S14) The stretched film is cut and rolled after corona treatment, and a longitudinal stretched polyethylene film 1 is obtained.

[0055] The middle layer of the longitudinal stretched polyethylene film 1 is composed of 100% metallocene polyethylene, the heat sealing layer is composed of 20% medium density metallocene polyethylene and 80% low pressure high density polyethylene resin, the density of the film is increased by arranging the low pressure high density polyethylene resin, and the heat resistance of the longitudinal stretched polyethylene film 1 is further increased, in the preparation method of the longitudinal stretched polyethylene film 1, the MDO stretching equipment process is arranged according to the raw material formula of each layer of the film, so that the film blown by the WH film blowing machine can be stretched longitudinally by 5 times on the MDO stretching equipment, and in specific implementation, the 100 mu m thick longitudinal stretched polyethylene film 1 is stretched by 5 times through the MDO stretching equipment, and becomes a 25 mu m thick longitudinal stretched polyethylene film 1. The longitudinal stretched polyethylene film 1 after stretching has changed molecular orientation and has certain mechanical properties, and the longitudinal stretched polyethylene film 1 after stretching has excellent mechanical properties and transparency, and is more suitable as a printing layer material.

[0056] The high moisture-resistant aluminum-plated polyethylene film 4 is made of a first layer A particle layer, a second layer B particle layer and a third layer C particle layer fused at high temperature, the first layer A particle layer accounts for 30%, the second layer B particle layer accounts for 40%, and the third layer C particle layer accounts for 30%, the first layer A particle layer is composed of 100% linear medium density polyethylene resin, the second layer B particle layer is composed of 80% low pressure high density polyethylene resin and 20% high pressure low density polyethylene resin, and the third layer C particle layer is composed of 80% medium density metallocene polyethylene, 19% high pressure low density polyethylene resin, 0.5% opening agent and 0.5% slip agent. In specific implementation, the high moisture-resistant aluminum-plated polyethylene film 4 is prepared by the following processing steps:

[0057] Step S21) The components are weighed and mixed according to the percentages of the layers of the high moisture-resistant aluminum-plated polyethylene film 4, and then are respectively added to the three barrels of the extruder to respectively prepare the mixed material of the first layer A particle layer, the mixed material of the second layer B particle layer and the mixed material of the third layer C particle layer.

[0058] Step S22) The mixture in the three barrels in step S21 is subjected to high-temperature melting by a high-temperature melting device of the extruder to form a tube blank, and the temperature required for high-temperature melting is 180-300 DEG C;

[0059] Step S23) After the tube blank is stretched, it is extruded from the center of the extruder die and compressed air is supplied so that the tube blank is blown into a film bubble, and the film bubble is cooled and shaped by a wind ring to obtain a film.

[0060] Step S24) The film obtained in step S23 is sent into an aluminizing machine, and the film is subjected to double corona vacuum evaporation to obtain a high-barrier wet polyethylene film.

[0061] The water vapor transmission rate of the high-barrier wet aluminized polyethylene film 4 prepared by steps S21-S24 is 0.5-0.8 g / (m 2 ·24h).

[0062] The third layer C particle layer of the present application uses 81% medium density metallocene polyethylene, which has strong anti-pollution ability and good sealing effect. When it is used in the high-barrier wet aluminized polyethylene film 4, it can achieve heat sealing effect and ensure that the package does not show liquid. The first layer A particle layer uses 100% linear medium density polyethylene resin, which can enhance the heat sealing effect of the medium density metallocene polyethylene. Since the metallocene polyethylene is mixed with the linear polyethylene, the film stiffness is not enough, and 15% high-pressure low-density polyethylene resin needs to be added to play an auxiliary production function, so that the tube blank is blown into a film bubble, the film bubble can be stably blown out, and the formability is improved.

[0063] The present application mixes the components of each layer structure of the high moisture-resistant aluminum-plated polyethylene film 4, and then adds them into three barrels of an extruder respectively to prepare a mixed material of the first layer A particle layer, a mixed material of the second layer B particle layer, and a mixed material of the third layer C particle layer. The mixed materials in the three barrels are subjected to high-temperature melting by a high-temperature heating and melting device of the extruder to form a tube blank. Then, the tube blank is stretched and extruded from the center of the extruder die, and compressed air is used to make the tube blank blow into a film bubble. At the same time, the film bubble is cooled and shaped by an air ring to prepare a film. The film prepared in step S23 is sent into an aluminum plating machine, and the film is subjected to double corona vacuum evaporation plating. The high moisture-resistant aluminum-plated polyethylene film 4 is obtained after the double corona vacuum evaporation plating treatment. The high moisture-resistant aluminum-plated polyethylene film 4 prepared in this way has a higher high-pressure low-density content compared with ordinary linear low-density polyethylene. Under the action of stress, it can achieve a higher crystallinity, thereby obtaining a smaller free volume fraction, increasing the glass transition temperature Tg of the polymer molecules, and improving the barrier properties of the material. After the corona steam aluminum plating, the barrier property of the high moisture-resistant aluminum-plated polyethylene film 4 is enhanced, and it also has light-shielding property and metal luster effect. The water vapor transmission rate of a conventional 40 μm PE is 2.0-4.0 g / (m 2 ·24h), and the water vapor transmission rate of the high moisture-resistant aluminum-plated polyethylene film 4 modified by the present application is 0.5-0.8 g / (m 2 ·24h), and the barrier property is greatly improved.

[0064] The high oxygen-resistant polyethylene film 6 in step S3) is prepared by co-extrusion of seven layers of a polyamide layer, a first low-density polyethylene layer, a first adhesive layer, an ethylene-vinyl alcohol copolymer layer with high oxygen resistance, a second adhesive layer, a second low-density polyethylene layer, and a polyethylene layer. The proportion of the polyamide layer is 25%, the proportion of the first low-density polyethylene layer is 15%, the proportion of the first adhesive layer is 5%, the proportion of the ethylene-vinyl alcohol copolymer layer is 10%, the proportion of the second adhesive layer is 5%, the proportion of the second low-density polyethylene layer is 15%, and the proportion of the polyethylene layer is 25%.

[0065] The polyamide layer of the high oxygen barrier polyethylene film 6 in step S3) is composed of 100% polyamide; the first low density polyethylene layer is composed of 72% linear low density polyethylene and 28% high pressure low density polyethylene; the first adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low density polyethylene; the ethylene-vinyl alcohol copolymer layer is composed of 26% polymerized vinyl acetate and 74% polymerized ethylene; the second adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low density polyethylene; the second low density polyethylene layer is composed of 72% linear low density polyethylene and 28% high pressure low density polyethylene; and the polyethylene layer is composed of 37% metallocene polyethylene, 30% linear low density polyethylene, 32% high pressure low density polyethylene, 0.52% opening agent and 0.5% slip agent. The high oxygen barrier polyethylene film 6 in step S3) is prepared by the following processing steps:

[0066] In step S31), the components are weighed according to the percentage corresponding to each layer of the high oxygen barrier polyethylene film 6 and mixed, and the mixture obtained by mixing each layer is added to the seven barrels of the extruder.

[0067] In step S32), the mixture in step S1 is added to the seven barrels of the extruder, and the mixture is heated and melted into a melt by the high temperature heating and melting device of the extruder. The temperature of the high temperature melting is 200-300°C. Seven layers of the polyamide layer, the first low density polyethylene layer, the first adhesive layer, the ethylene-vinyl alcohol copolymer layer with high oxygen barrier property, the second adhesive layer, the second low density polyethylene layer and the polyethylene layer are prepared, respectively. Then, the seven layers are co-extruded by the extruder, and then distributed by the flow channel distributor and converged and heated in the T-shaped die.

[0068] In step S33), the resin film flowed out after the convergence and heating in the T-shaped die is cooled and shaped by the cooling roller to obtain the high oxygen barrier polyethylene film 6. The density of the obtained high oxygen barrier polyethylene film 6 is 1.12 g / cm 3 The oxygen transmission rate of the high oxygen barrier polyethylene film 6 is ≤5.0 cm 3 / (㎡·24h·0.1MPa), the friction coefficient of the high oxygen barrier polyethylene film 6 is 0.44-0.48, the required temperature for heating in the T-shaped die is 250-300°C, and the cooling temperature is 15-25°C.

[0069] In step S34), the high oxygen barrier polyethylene film 6 is edge cut and wound by the winding machine.

[0070] The thickness of the ethylene-vinyl alcohol copolymer layer of the present application is 7 μm, and the melt flow index of the polymerized ethylene in the ethylene-vinyl alcohol copolymer layer is 6-12 g / 10 min.

[0071] The first bonding layer and the second bonding layer of the application are both composed of 50% adhesive resin and 50% linear low density polyethylene, the adhesive effect of the adhesive resin is good, the polyamide layer, the high density polyethylene layer and the ethylene-vinyl alcohol copolymer layer can be well bonded together, and the density of the polyamide in the polyamide layer is 1.15g / cm 3 , the polyamide also has good tensile strength, puncture resistance and good oxygen resistance, the use of the two high density polyethylene layers makes the high oxygen resistance polyethylene film 6 have better oxygen barrier performance. In addition, the middle layer of the high oxygen resistance polyethylene film 6 of the application is mainly composed of an ethylene-vinyl alcohol copolymer layer, the ethylene-vinyl alcohol copolymer has excellent barrier property to gas and excellent processability, effectively preventing the penetration of external water vapor and gas into the packaging contents, and has excellent heat sealing performance, strong anti-pollution ability, very good heat sealing strength, and the ethylene-vinyl alcohol copolymer has good affinity with polyamide, the ethylene-vinyl alcohol copolymer has high glass transition temperature and can adapt to molding processing, which can change the disadvantage of easy deformation of the polyamide film layer when heated. In addition, the high oxygen resistance polyethylene film 6 prepared by the application has moderate friction coefficient, does not stick and slip when cut, and is very suitable for high-speed packaging production line.

[0072] I. The application will be further described below in combination with two specific embodiments provided by the application:

[0073] 1. In the second embodiment of the application, the polyethylene composite material of the application can be prepared and processed by using the following film layers and components corresponding to the film layers, and the specific film layer structure is shown in Table 1 below:

[0074] Table 1

[0075] 2. In the third embodiment of the application, the polyethylene composite material of the application can be prepared by using the following processing method, and the specific preparation process includes the following steps:

[0076] Step S1) gravure printing process: the prepared 25μm thick longitudinal stretch polyethylene film 1 is loaded on the first feeding shaft of the gravure printing machine, and the following processing steps are used to prepare the longitudinal stretch polyethylene film 1:

[0077] Step S11) The longitudinal stretching polyethylene film 1 is configured with the following components in weight percentage, the heat sealing layer is composed of 20% medium density metallocene polyethylene and 80% low pressure high density polyethylene resin; the intermediate layer is composed of 100% metallocene polyethylene; the corona layer is composed of 29% medium density metallocene polyethylene, 70% low pressure high density metallocene polyethylene, 0.5% opening agent and 0.5% slip agent. Then, the components of each layer are mixed, and the mixture of each layer is added to the three barrels of the WH film blowing machine to prepare the mixture of the heat sealing layer, the mixture of the intermediate layer and the mixture of the corona layer. The mixture is plasticized into a melt by high temperature heating under the three barrels of the WH film blowing machine, and the temperature of the high temperature heating is 250℃;

[0078] Step S12) The melt is extruded into a melt film through the three-layer co-extrusion film blowing die of the WH film blowing machine, the extrusion speed is 550 Kg / h, and the melt film is blown into a film bubble through the WH film blowing machine, and then cooled;

[0079] Step S13) The cooled and shaped film is flattened, and the film enters the MDO stretching equipment of the WH film blowing machine under the action of the rotating traction roller to perform a stretching process. The temperature during the longitudinal stretching is 90℃, the stretching ratio of the film is 5, and the film is heat set at 150℃ after stretching;

[0080] Step S14) The stretched film is edge cut and rolled after corona treatment, and a longitudinal stretching polyethylene film 1 is obtained;

[0081] The 25μm thick longitudinal stretching polyethylene film 1 is sent to each printing color unit through the first unwinding shaft of the printing machine, and the longitudinal stretching polyethylene film 1 is used as a substrate for intaglio printing. A layer of polyurethane ink layer 2 is printed on the surface of the longitudinal stretching polyethylene film 1, the ink viscosity is controlled at 15 viscosity / Pa.s, the tension required for the first unwinding roller of the printing machine to unwind the longitudinal stretching polyethylene film 1 is 100N, and the winding tension after printing is 120N;

[0082] Step S2) First pass composite treatment: the 25μm thick longitudinal stretching polyethylene film 1 printed in step 1 is loaded into the second unwinding shaft end, the tension required for the second unwinding shaft to unwind the 25μm thick longitudinal stretching polyethylene film 1 is 120N, and the prepared 40μm thick high moisture-resistant aluminum-coated polyethylene film 4 is loaded into the third unwinding shaft end. The high moisture-resistant aluminum-coated polyethylene film 4 is prepared by the following processing steps,

[0083] Step S21) The high-barrier wet aluminum-plated polyethylene film 4 is configured with the following components in weight percentage: 100% linear medium-density polyethylene resin for the first layer A particle layer, 80% low-pressure high-density polyethylene resin and 20% high-pressure low-density polyethylene resin for the second layer B particle layer; 80% medium-density metallocene polyethylene, 19% high-pressure low-density polyethylene resin, 0.5% opening agent, and 0.5% slip agent for the third layer C particle layer. The components corresponding to each layer are mixed, and then added to the three barrels of the extruder respectively to obtain the mixed material of the first layer A particle layer, the mixed material of the second layer B particle layer, and the mixed material of the third layer C particle layer.

[0084] Step S22) The mixed materials in the three barrels of the extruder are subjected to high-temperature melting by the high-temperature melting device of the extruder to form a tube blank. The temperature required for high-temperature melting is 300°C.

[0085] Step S23) After stretching the tube blank, it is extruded from the center of the extruder die and compressed air is supplied to make the tube blank blow into a film bubble. At the same time, the film bubble is cooled and shaped by the air ring to obtain a film.

[0086] Step S24) The film obtained in step S23 is sent into an aluminum plating machine for double-corona vacuum evaporation plating to obtain a high-barrier wet polyethylene film.

[0087] The tension required for the third feeding shaft to feed the high-barrier wet aluminum-plated polyethylene film 4 is 140N. The 25μm thick longitudinally stretched polyethylene film 1 is fed into the first gluing system through the second feeding shaft end. The first gluing roller of the first gluing system applies the first layer of double-component polyurethane adhesive 3 to the inner surface of the 25μm thick longitudinally stretched polyethylene film 1. The 25μm thick longitudinally stretched polyethylene film 1 is sent into the oven for drying to volatilize the organic solvents in the first layer of double-component polyurethane adhesive 3. The 25μm thick longitudinally stretched polyethylene film 1 enters the three drying channels in the oven for drying. The temperatures of the three drying channels are 50°C, 60°C, and 70°C respectively. The longitudinally stretched polyethylene film 1 after drying in the three drying channels is hot-pressed with the treated surface of the high-barrier wet aluminum-plated polyethylene film 4 to form a semi-finished composite film. The pressure required for the hot-pressing process of the hot-pressing guide roller is 0.35Mpa, and the composite speed is 90M / min. The gluing mesh of the first gluing roller is 110*75 concave mesh, the gluing amount is 3.2g / ㎡, and the tension required for winding the semi-finished composite film is 200N.

[0088] Step S3) Second time compounding process: the first time compounded semi-finished product composite film is loaded into the fourth feed shaft end, and the required tension for the semi-finished product composite film is 160 N. The prepared 70 μm thick high oxygen barrier polyethylene film 6 is loaded into the fifth feed shaft end. The high oxygen barrier polyethylene film 6 is prepared by the following steps,

[0089] Step S31) The high oxygen barrier polyethylene film 6 is configured by the following weight percentage components. The polyamide layer is taken as 100% polyamide, the first low density polyethylene layer is taken as 72% linear low density polyethylene and 28% high pressure low density polyethylene, the first adhesive layer is taken as 40% adhesive resin and 60% linear low density polyethylene, the ethylene-vinyl alcohol copolymer layer is taken as 26% polymerized vinyl acetate and 74% polymerized ethylene, the second adhesive layer is taken as 40% adhesive resin and 60% linear low density polyethylene, the second low density polyethylene layer is taken as 72% linear low density polyethylene and 28% high pressure low density polyethylene, and the polyethylene layer is taken as 37% metallocene polyethylene, 30% linear low density polyethylene, 32% high pressure low density polyethylene, 0.5% opening agent and 0.5% slip agent. The corresponding components of each layer are mixed, and the mixed material of each layer is added to the seven barrels of the extruder;

[0090] Step S32) The mixture in step S1 is added to the seven barrels of the extruder, and the high temperature melting device of the extruder is used for heating and melting to form a melt. The temperature of the high temperature melting is 200-300℃. Seven layers of polyamide layer, first low density polyethylene layer, first adhesive layer, ethylene-vinyl alcohol copolymer layer, second adhesive layer, second low density polyethylene layer and polyethylene layer are respectively prepared. Then, the extruder is co-extruded, and then the resin is flowed through the flow channel distributor and is converged and heated in the T-shaped die;

[0091] Step S33) The resin film flowed out after the convergence and heating of the T-shaped die is cooled and shaped by the cooling roller to obtain the high oxygen barrier polyethylene film 6. The required temperature of the T-shaped die is 250℃, and the cooling temperature is 15℃. The required temperature of the T-shaped die is 250℃, and the cooling temperature is 15℃.

[0092] Step S34) The high oxygen barrier polyethylene film 6 is edge cut, and is wound by the winding machine.

[0093] The tension required for discharging the high-oxygen-barrier polyethylene film 6 through the fifth discharging shaft is 140 N. The semi-finished product composite film is introduced into the second gluing system through the fourth discharging shaft. The second gluing roller of the second gluing system applies the second layer of two-component polyurethane adhesive 5 to the inner surface of the 40 μm-thick high-wet-barrier aluminum-coated polyethylene film 4. The semi-finished product composite film is introduced into the drying oven to volatilize the organic solvent in the second layer of two-component polyurethane adhesive 5. The semi-finished product composite film is dried in the three drying channels in the drying oven. The temperatures of the three drying channels are 50°C, 60°C and 70°C, respectively. The semi-finished product composite film is hot-pressed with the inner surface of the treated surface of the high-oxygen-barrier polyethylene film 6 to form a polyethylene composite material. The pressure required for the hot-pressing process of the polyethylene composite material hot-pressing guide roller is 0.35 MPa. The composite speed is 90 m / min. The gluing mesh of the second gluing roller is 110*75 concave mesh. The gluing amount is 3.2 g / m2. The tension required for winding the polyethylene composite material is 240 N.

[0094] II. The polyethylene composite material prepared by the method of Example Three is cut to test the barrier properties and heat sealing properties. The test conditions are as follows:

[0095] 1. Test method: The moisture permeability of the polyethylene composite material is tested according to the method specified in the national standard GB / T 26253. The test conditions are as follows: the test temperature is 38°C, the relative humidity is 90%, and the heat sealing surface is directed to the side with low humidity during the test.

[0096] The oxygen transmission rate of the polyethylene composite material is tested according to the method specified in the national standard GB / T 1038-1988. The non-heat-sealing surface is directed to the oxygen side during the test.

[0097] The polyethylene composite material prepared in Example Three is heat sealed under a sealing pressure of 200 kPa according to the method specified in the national standard QB / T 2358. The width of the polyethylene composite material cut from Example Three is 15 mm, and the length is 100 mm. The heat sealing strength of the polyethylene composite material is plotted against the heat sealing time. The optimal heat sealing temperature and heat sealing strength are recorded.

[0098] 2. Test results: see Table 2 below:

[0099]

[0100] 3. Test conclusion: As shown in Table 2 above, the polyethylene composite material prepared by the processing method of the present application not only has excellent water vapor barrier properties and oxygen barrier properties, but also has high heat sealing properties. The water vapor barrier properties and oxygen barrier properties in Example Five are more significant.

[0101] III. The polyethylene composite material prepared by the method of embodiment III is subjected to mechanical property testing, and the testing conditions are as follows:

[0102] 1. Test method: the breaking force and elongation at break of the polyethylene composite material are tested according to the method of GB / T 1040.3;

[0103] 2. Test results: see Table 3 below:

[0104]

[0105] 3. Test conclusion: as shown in Table 3 above, the polyethylene composite material prepared by the processing method of the application has excellent mechanical properties.

[0106] IV. Material identification of each layer of the polyethylene composite material prepared in embodiment III:

[0107] Each layer of the polyethylene environmental protection composite material prepared in embodiment III is peeled off, the glue between the layers of the polyethylene composite material is wiped off using a solvent, and then material identification is performed using an infrared spectroscopy instrument. The detection conditions of the polyethylene composite material using the longitudinal stretching polyethylene film 1, the high-wet-resistance aluminum-plated polyethylene film 4, and the high-oxygen-resistance polyethylene film 6 are as shown in Table 4 below. Figs. 3-5 From the spectrum of the infrared spectrometer, Figs. 3-5 it can be concluded that the structure of each layer of the polyethylene composite material is a single polyethylene environmental protection composite material.

[0108] In summary, the polyethylene composite material prepared by the processing method of the application is a three-layer film stack composite using the longitudinal stretching polyethylene film 1, the high-wet-resistance aluminum-plated polyethylene film 4, and the high-oxygen-resistance polyethylene film 6 as the polyethylene composite material. The longitudinal stretching polyethylene film 1 is used as the outer layer, the high-wet-resistance aluminum-plated polyethylene film 4 is used as the middle layer, and the high-oxygen-resistance polyethylene film 6 is used as the inner layer. Each layer of film uses a unique formula design, making the polyethylene composite material easier to process during preparation. Not only does it improve the barrier property and heat sealing performance of the polyethylene composite material, but also improves the mechanical properties.

[0109] The application has been described in detail above, and the above description is only a preferred embodiment of the application. The application is not limited by the above description, and any equivalent changes and modifications made within the scope of the application should still fall within the scope of the application.

Claims

1. A process for the preparation of a polyethylene composite material, characterized in that: The application relates to a processing method for processing a polyethylene composite material, wherein the polyethylene composite material is prepared by processing a longitudinally stretched polyethylene film, a polyurethane ink layer, a first layer of double-component polyurethane adhesive, a high-wet-resistance aluminized polyethylene film, a second layer of double-component polyurethane adhesive and a high-oxygen-resistance polyethylene film; the processing method comprises the following steps: Step S1): gravure printing treatment: the prepared 25-micron-thick longitudinally stretched polyethylene film is loaded on a first feeding shaft of a gravure printing machine, the 25-micron-thick longitudinally stretched polyethylene film is sent to each printing color unit through the first feeding shaft of the printing machine, gravure printing is performed on the longitudinally stretched polyethylene film as a base material, a polyurethane ink layer is printed on the surface of the longitudinally stretched polyethylene film, the viscosity of the ink is controlled to be 13-17 viscosity / Pa.s, the tension required for unwinding the longitudinally stretched polyethylene film by the first unwinding roller of the printing machine is 100 N, and the winding tension after printing is completed is 120 N; Step S2): first-time composite treatment: the 25-micron-thick longitudinally stretched polyethylene film printed in step 1 is loaded on the second feeding shaft end, the tension required for feeding the 25-micron-thick longitudinally stretched polyethylene film by the second feeding shaft is 120 N, the prepared 40-micron-thick high-wet-resistance aluminized polyethylene film is loaded on the third feeding shaft end, the tension required for feeding the 40-micron-thick high-wet-resistance aluminized polyethylene film by the third feeding shaft is 140 N, the 25-micron-thick longitudinally stretched polyethylene film is sent into the first gluing system through the second feeding shaft end, the first gluing roller of the first gluing system is used for coating the first layer of double-component polyurethane adhesive on the processing surface of the 25-micron-thick longitudinally stretched polyethylene film, the 25-micron-thick longitudinally stretched polyethylene film after coating is sent into an oven for drying, and the organic solvent in the first layer of double-component polyurethane adhesive is volatilized; the 25-micron-thick longitudinally stretched polyethylene film enters three drying channels in the oven for drying, the temperatures of the three drying channels are 50 DEG C, 60 DEG C and 70 DEG C respectively, the processing surfaces of the longitudinally stretched polyethylene film and the high-wet-resistance aluminized polyethylene film after drying through the three drying channels are subjected to hot-pressing composite to form a semi-finished product composite film, the pressure required in the hot-pressing process of the hot-pressing guide roller is 0.35 Mpa, the composite speed is 90 M / min, the gluing mesh of the first gluing roller is 110*75 gravure mesh roller, the gluing amount is 3.2-3.5 g / m2, and the tension required for winding the semi-finished product composite film is 200 N; The high-wet-resistance aluminized polyethylene film is made of a first layer of A particle layer, a second layer of B particle layer and a third layer of C particle layer fused at high temperature, the proportion of the first layer of A particle layer is 30%, the proportion of the second layer of B particle layer is 40%, and the proportion of the third layer of C particle layer is 30%; the first layer of A particle layer is composed of 100% linear medium-density polyethylene resin; the second layer of B particle layer is composed of 80% low-pressure high-density polyethylene resin and 20% high-pressure low-density polyethylene resin; and the third layer of C particle layer is composed of 80% medium-density metallocene polyethylene, 19% high-pressure low-density polyethylene resin, 0.5% opening agent and 0.5% slip agent. Step S3) Second time compounding process: the first time compounded semi-finished product composite film is loaded into the fourth feed shaft end, the tension required for the fourth feed shaft to feed the semi-finished product composite film is 160N, the prepared 70μm thick high oxygen barrier polyethylene film is loaded into the fifth feed shaft end, the tension required for the fifth feed shaft to feed the 70μm thick high oxygen barrier polyethylene film is 140N, the semi-finished product composite film is sent into the second gluing system through the fourth feed shaft, the second gluing roller of the second gluing system applies the second layer of two-component polyurethane adhesive on the inner surface of the 40μm thick high moisture barrier aluminum-coated polyethylene film, the coated semi-finished product composite film enters the oven for drying, and the organic solvent in the second layer of two-component polyurethane adhesive is volatilized, the semi-finished product composite film enters the three ovens in the oven for drying, the temperatures of the three ovens are 50℃, 60℃ and 70℃ respectively, the semi-finished product composite film is hot-pressed with the inner surface of the treated surface of the high oxygen barrier polyethylene film to form a polyethylene composite material, the pressure required for the hot-pressing process of the polyethylene composite material hot-pressing guide roller is 0.35Mpa, the compounding speed is 90M / min, the gluing mesh of the second gluing roller is 110*75 concave screen mesh roller, the gluing amount is 3.2-3.5g / ㎡, and the tension required for the polyethylene composite material to be wound is 240N. The high oxygen barrier polyethylene film is formed by seven layers of co-extrusion, i.e., a polyamide layer, a first low-density polyethylene layer, a first adhesive layer, an ethylene-vinyl alcohol copolymer layer, a second adhesive layer, a second low-density polyethylene layer and a polyethylene layer, the proportion of the polyamide layer is 25%, the proportion of the first low-density polyethylene layer is 15%, the proportion of the first adhesive layer is 5%, the proportion of the ethylene-vinyl alcohol copolymer layer is 10%, the proportion of the second adhesive layer is 5%, the proportion of the second low-density polyethylene layer is 15%, and the proportion of the polyethylene layer is 25%. The polyamide layer of the high oxygen barrier polyethylene film is composed of 100% polyamide, the first low-density polyethylene layer is composed of 72% linear low-density polyethylene and 28% high-pressure low-density polyethylene, the first adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low-density polyethylene, the ethylene-vinyl alcohol copolymer layer is composed of 26% polymerized vinyl acetate and 74% polymerized ethylene, the second adhesive layer is composed of 40-50% adhesive resin and 50-60% linear low-density polyethylene, the second low-density polyethylene layer is composed of 72% linear low-density polyethylene and 28% high-pressure low-density polyethylene, and the polyethylene layer is composed of 37% metallocene polyethylene, 30% linear low-density polyethylene, 32% high-pressure low-density polyethylene, 0.5% opening agent and 0.5% slip agent.

2. The process for the preparation of polyethylene composites according to claim 1, characterized in that: The first layer of two-component polyurethane adhesive and the second layer of two-component polyurethane adhesive used in steps S2) and S3) are of the type "XH-66F / XH-K75", the ratio of the two-component polyurethane adhesive is: main agent XH-66F: curing agent XH-K75: ethyl acetate solvent = 20:3.8:

26.

3. The process for the preparation of polyethylene composites according to claim 1, characterized in that: The longitudinal stretched polyethylene film in step S1) is made of a heat sealing layer, an intermediate layer and a corona layer, the heat sealing layer accounts for 30%, the intermediate layer accounts for 40%, and the corona layer accounts for 30%; the heat sealing layer is composed of 20% medium density metallocene polyethylene and 80% low pressure high density polyethylene resin; the intermediate layer is composed of 100% metallocene polyethylene; and the corona layer is composed of 29% medium density metallocene polyethylene, 70% low pressure high density metallocene polyethylene, 0.5% opening agent and 0.5% slip agent.

4. The process for the preparation of polyethylene composites according to claim 3, characterized in that: The longitudinal stretched polyethylene film in step S1) is prepared by the following processing steps: Step S11) each component is weighed and mixed according to the percentage corresponding to each layer of the longitudinal stretched polyethylene film, and the mixture of each layer is added to the three barrels of the WH film blowing machine to prepare the mixture of the heat sealing layer, the mixture of the intermediate layer and the mixture of the corona layer, respectively, and the mixture is plasticized into a melt by high temperature heating under the three barrels of the WH film blowing machine, and the temperature of the high temperature heating is 180-250℃; Step S12) the melt is extruded into a melt film through the three-layer co-extrusion film blowing die head of the WH film blowing machine, the extrusion speed is 550-600 Kg / h, and the melt film is blown into a bubble through the WH film blowing machine, and then is cooled; Step S13) the cooled and formed film is flattened, and the film enters the MDO stretching equipment of the WH film blowing machine under the action of the rotating traction roller to perform a stretching process, the temperature during the longitudinal stretching is 90-100℃, the stretching ratio of the film is 5, and the film is heat set at 150℃ after stretching; Step S14) the stretched film is cut and rolled after corona treatment, and a longitudinal stretched polyethylene film is prepared.

5. The process for the preparation of polyethylene composites according to claim 1, characterized in that: The high moisture resistance aluminum plated polyethylene film in step S2) is prepared by the following processing steps: Step S21) each component is weighed and mixed according to the percentage corresponding to each layer of the high moisture resistance aluminum plated polyethylene film, and then is added to the three barrels of the extruder to prepare the mixture of the first layer A particle layer, the mixture of the second layer B particle layer and the mixture of the third layer C particle layer, respectively; Step S22) the mixtures in the three barrels of the extruder are high temperature melted through the high temperature melting device of the extruder to form a tube blank, and the temperature required for the high temperature melting is 180-300℃; Step S23) the tube blank is stretched and extruded from the center of the extruder die head and compressed air, so that the tube blank is blown into a film bubble, and the film bubble is cooled and shaped through the air ring to prepare a film; Step S24) the film prepared in step S23 is sent into an aluminum plating machine, and the film is subjected to double corona vacuum evaporation, and a high moisture resistance aluminum plated polyethylene film is obtained after the double corona vacuum evaporation treatment.

6. The process for the preparation of polyethylene composites according to claim 5, characterized in that: The water vapor permeability of the high-barrier wet aluminum plated polyethylene film prepared by the steps S21) - S24) is 0.5 - 0.8 g / (m 2 ·24h).

7. The process for the preparation of polyethylene composites according to claim 1, characterized in that: The high oxygen resistance polyethylene film in step S3) is prepared by the following processing steps: Step S31) each component is weighed and mixed according to the percentage corresponding to each layer component of the high oxygen resistance polyethylene film, and the mixture obtained by mixing each layer is added to the seven barrels of the extruder; Step S32) The seven materials in step S1 are mixed into seven barrels of an extruder, heated and melted into a melt by a high-temperature heating and melting device of the extruder, the temperature of the high-temperature melting is 200-300℃, and seven layers of the polyamide layer, the first low-density polyethylene layer, the first adhesive layer, the ethylene-vinyl alcohol copolymer layer, the second adhesive layer, the second low-density polyethylene layer and the polyethylene layer are respectively prepared, then co-extruded by the extruder, and then converged and heated in a T-shaped die after flowing through a runner distributor; Step S33) The resin film flowed out after heating is converged through a T-shaped die, and the high oxygen barrier polyethylene film is formed after cooling through a cooling roller. The density of the high oxygen barrier polyethylene film is 1.12 g / cm 3 , the oxygen transmission rate of the high oxygen barrier polyethylene film is ≤5.0 cm 3 / (m2·24h·0.1MPa), the friction coefficient of the high oxygen barrier polyethylene film is 0.44-0.48, the temperature required for heating the T-shaped die is 250-300℃, and the cooling temperature is 15-25℃. Step S34) The high-oxygen-barrier polyethylene film is edge cut and wound by a winding machine.

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