High-gloss multi-layer co-extrusion sheet for hose packaging and preparation method of high-gloss multi-layer co-extrusion sheet

Abstract

The invention belongs to the technical field of packaging materials, and particularly relates to a high-gloss multi-layer co-extrusion sheet for hose packaging and a preparation method of the high-gloss multi-layer co-extrusion sheet. The high-gloss multi-layer co-extrusion sheet for hose packaging structurally comprises a high-gloss composite base material layer, a reinforcing layer, a bonding layer and an inner layer in sequence. The high-gloss layer, the reinforcing layer, the bonding layer and the inner layer are functionally partitioned, and the preparation method and the raw material components and the thickness of each layer are controlled, so that the mechanical strength and the barrier property of the sheet are balanced. The high-gloss layer provides appearance and basic barrier, the reinforcing layer provides mechanical support, the bonding layer achieves cross-layer connection, the inner layer completes a heat sealing function, a synergistic system is formed on a micromechanism, and finally the sheet has the comprehensive performance of metal-like gloss, high barrier, high strength and high-layer combination at the same time. And the high-end requirements of cosmetics, medicines and food hose packaging are completely met.

Description

Technical Field

[0001] This invention belongs to the field of packaging materials technology, specifically relating to a high-gloss multilayer co-extruded sheet for tube packaging and its preparation method. Background Technology

[0002] In the cosmetics, pharmaceutical and food industries, soft tube packaging is in high demand due to its convenience and good sealing performance. In 2023, the domestic market size of cosmetic packaging soft tubes reached 12.76 billion yuan. Moreover, with the upgrading of consumption, cosmetic packaging soft tubes are developing towards "high performance and high appearance".

[0003] Currently, there are two main processes for tube manufacturing: extrusion and sheet manufacturing. Extrusion offers high production efficiency, but its appearance and function depend on subsequent printing, resulting in poor gloss and barrier properties, making it difficult to meet high-end demands. Sheet manufacturing, on the other hand, offers high flexibility and allows for material composites, making it the mainstream direction for high-end packaging. While foreign countries have developed high-gloss, high-barrier sheets through multi-layer composite technology, China faces significant shortcomings—insufficient material composite precision, high sheet haze, poor barrier performance and interlayer bonding strength, leading to delamination and leakage. Furthermore, tube manufacturing suffers from several other problems, such as the difficulty of balancing high gloss and low haze, the high temperature of extrusion lamination causing oxidation of the VMPET aluminized layer, poor compatibility of dissimilar materials affecting tube manufacturing performance, and insufficient compatibility between dry and extrusion lamination processes.

[0004] In summary, there is an urgent need to develop a high-gloss multilayer co-extruded sheet for tube packaging that combines high gloss, high barrier properties, stable bonding strength, and excellent tube-making performance, suitable for industries such as cosmetics, pharmaceuticals, and food. Summary of the Invention

[0005] The purpose of this invention is to provide a high-gloss multilayer co-extruded sheet for tube packaging and its preparation method. By dividing the sheet into four functional layers—high-gloss layer, reinforcing layer, adhesive layer, and inner layer—and controlling the preparation method and the raw material composition and thickness of each layer, the mechanical strength and barrier properties of the sheet are balanced, fully meeting the high-end requirements of tube packaging for cosmetics, pharmaceuticals, and food.

[0006] A high-gloss multilayer co-extruded sheet for tube packaging, the structure of which consists of a high-gloss composite substrate layer, a reinforcing layer, an adhesive layer, and an inner layer.

[0007] Preferably, the thickness of the high-gloss composite substrate layer is 100-135 μm.

[0008] Preferably, the thickness of the reinforcing layer is 90-110 μm.

[0009] Preferably, the thickness of the adhesive layer is 15-25 μm.

[0010] Preferably, the thickness of the inner layer is 130-160 μm.

[0011] Preferably, the raw materials for preparing the reinforcing layer include metallocene-catalyzed polyethylene and HDPE.

[0012] Preferably, the metallocene-catalyzed polyethylene has a melt index of 1.0 g / 10 min and a density of 0.918 g / cm³ at 190°C. 3 .

[0013] In some preferred embodiments, the metallocene-catalyzed polyethylene is derived from ExxonMobil, ExxonMobil Exceed 1018CA.

[0014] Preferably, the HDPE has a melt flow index of 2.0 g / 10 min and a density of 0.954 g / cm³ at 190°C. 3 .

[0015] In some preferred embodiments, the HDPE is sourced from LyondellBasell, Lupolen 5261 Z.

[0016] Preferably, the mass ratio of the metallocene-catalyzed polyethylene to HDPE is 1:(1-1.8); more preferably, it is 1:1.4.

[0017] Preferably, the raw materials for preparing the adhesive layer include EMA and MAH-g-PE.

[0018] Preferably, the EMA contains 9% MA and has an elongation at break of ≥700%.

[0019] In some preferred embodiments, the EMA is from DuPont, USA, 1609 AC.

[0020] Preferably, the MAH-g-PE has a melt index of 5.5-6.5 g / 10 min at 190°C and a MAH grafting rate of 1%-1.3%.

[0021] In some preferred embodiments, the MAH-g-PE is sourced from Dongguan Shenghao Plastic Raw Materials Co., Ltd., PE-12L.

[0022] Preferably, the mass ratio of EMA to MAH-g-PE is (2-3):1; more preferably, it is 7:3.

[0023] Preferably, the raw materials for preparing the inner layer include ionomers and antioxidants.

[0024] Preferably, the ionomer is an ethylene-methacrylic acid-based ionomer with a melt index of 2-4 g / 10 min at 190°C and an IZOD notched impact strength of 19-20 KJ / m at 23°C.

[0025] In some preferred embodiments, the ionomer is derived from DuPont, Surlyn® Resin, 8940.

[0026] Preferably, the antioxidant is antioxidant 1010, and the amount added is 0.4%-0.6% of the mass of the ionomer.

[0027] By designing a reinforcing layer, adhesive layer, and inner layer as the main structure of the sheet, and controlling the raw materials and thickness of each layer, the mechanical properties and interlayer strength of the sheet can be improved, making the resulting sheet more suitable for tubular packaging. This is likely because the reinforcing layer uses specific metallocene-catalyzed polyethylene and HDPE as raw materials, providing rigidity, stiffness, and structural support to the sheet, improving its mechanical properties and making it less prone to deformation. However, this single layer can lead to an overly rigid sheet, unsuitable for tubular packaging. The inner layer, prepared primarily from ionomers, compensates for the deficiencies of the reinforcing layer, making the sheet both less prone to deformation and flexible, facilitating tubing fabrication and extrusion of contents. However, the poor compatibility between the reinforcing layer and the inner layer results in poor interlayer peel strength after ordinary lamination, affecting the sheet's performance. Using specific EMA and MAH-g-PE to prepare the adhesive layer can achieve a stress transition effect, preventing interlayer peeling. The MAH-g-PE adhesive layer possesses intrinsic compatibility with the PE molecular chains of the reinforcing layer, forming a strong physical bond through interdiffusion and entanglement of the molecular chains. Furthermore, its grafted anhydride groups can chemically interact with weak points on the PE chains, resulting in an extremely robust interface during co-extrusion. Simultaneously, the inner layer raw material ionomer contains a large number of carboxylate ions. The ester groups in the EMA backbone exhibit excellent compatibility and polar interaction with the ionic bonds and carboxylate groups of the ionomer. The anhydride groups of MAH-g-PE can undergo esterification or amidation reactions with the carboxylic acids or hydroxyl groups at the ends of the ionomer molecular chains at processing temperatures, forming strong covalent bonds.

[0028] Preferably, the high-gloss composite substrate layer has the following structure in sequence: PE layer, EPE layer, CPE layer and VMPET layer.

[0029] Preferably, the thickness of the PE layer is 55-65 μm.

[0030] Preferably, the thickness of the EPE layer is 15-25 μm.

[0031] Preferably, the thickness of the CPE layer is 20-30 μm.

[0032] Preferably, the thickness of the VMPET layer is 10-15 μm.

[0033] The method for preparing the PE layer includes the following steps: adding PE raw material into a casting machine for melting, extruding, and then cooling with a cooling roller to obtain the PE layer.

[0034] Preferably, the PE raw material has a melt flow index of 0.5-0.7 g / 10 min and a density of 0.91-0.93 g / cm³ at 190°C. 3 .

[0035] In some preferred embodiments, the PE raw material is sourced from Westlake Corporation, specifically linear low-density polyethylene resin LF74580.

[0036] Preferably, the melting temperature is 200-240℃, the cooling roller temperature is 20-25℃, and the traction speed is 80-100m / min.

[0037] The raw materials for preparing the EPE layer are the same as those for preparing the adhesive layer. The preparation method is as follows: mix EMA and MAH-g-PE, melt co-extrude, and then cast and cool to obtain the final product.

[0038] Preferably, the specific conditions for the melt co-extrusion are: extruder temperature of 180-200℃, die temperature of 190℃, and screw speed of 45rpm.

[0039] Preferably, the specific conditions for the casting cooling are: the temperature of the cooling roller is 25°C and the traction speed is 15m / min.

[0040] The method for preparing the CPE layer includes the following steps: mixing CPE and additives at high speed, then extruding with a twin-screw extruder and calendering to obtain the final product.

[0041] Preferably, the chlorine content of the CPE is 34%-36%, and the elongation at break is ≥600%.

[0042] In some preferred embodiments, the CPE is sourced from Asia Star Chemicals, WEIPREN®RESIN, 6100.

[0043] Preferably, the additives include calcium stearate and epoxidized soybean oil in a mass ratio of 1:2, and the total amount added is 1%-2% of the mass of chlorinated polyethylene resin.

[0044] Preferably, the specific conditions for high-speed mixing are: a rotation speed of 800-1200 rpm and a time of 8-12 min.

[0045] Preferably, the specific conditions for the twin-screw extrusion are: temperature of 160-200℃, vacuum degree of 0.08-0.09MPa, and screw speed of 60rpm.

[0046] Preferably, the specific conditions for calendering are: the temperature of the three-roll calender is 150-160℃, and the roll gap is 0.25mm.

[0047] The VMPET layer is prepared by pretreating the PET base film and then vacuum-depositing aluminum.

[0048] Preferably, the PET base film has a thickness of 12 μm and is sourced from Yihua Toray Polyester Film Co., Ltd., PET12.

[0049] Preferably, the pretreatment is corona treatment, which is performed until the wetting tension of the PET base film surface is 48-52 dyn / cm.

[0050] Preferably, the specific conditions for vacuum aluminum plating are: the plating method is vapor deposition, and the vacuum degree is 2×10⁻⁶. -4 -1×10 - 3 Pa, evaporation temperature is 1100-1200℃, deposition rate is 14-16nm / s, and aluminum layer thickness is 40-60nm.

[0051] By designing PE, EPE, CPE, and VMPET layers as high-gloss composite substrate layers and controlling the raw materials and thickness of each layer, the surface gloss and barrier properties of the sheet can be improved. This is likely because the structures of the PE, EPE, CPE, and VMPET layers form a gradient transition from non-polar and flexible to polar and rigid. The outermost PE layer provides smoothness and high gloss; the underlying EPE layer acts as the first stress buffer layer, absorbing external impacts; the CPE layer, as a strongly polar functional layer, is compatible with the EPE layer, and its chlorine atoms can form strong interactions with the VMPET layer, while avoiding potential corrosion of the aluminized layer by acidic components in the adhesive layer; the innermost VMPET layer provides the core light reflectivity and barrier properties. The synergistic effect of these layers disperses stress between materials of different polarities, avoids micro-wrinkles caused by differences in thermal shrinkage, and allows the aluminized surface to completely replicate the mirror roughness of the cooling roller, improving the sheet's gloss and barrier properties while providing a foundation for subsequent lamination.

[0052] The method for preparing the high-gloss multilayer co-extruded sheet for tube packaging includes the following steps: S1. Prepare a high-gloss composite substrate layer; S2. Mix and melt the raw materials of the reinforcing layer, extrude them into a film, and then press the film with a high-gloss composite substrate layer. Cool the film to 20-25℃ to obtain semi-finished product 1. S3. After the raw materials of the adhesive layer and the inner layer are melted and mixed separately, a composite melt curtain is formed by co-extrusion process. The melt curtain is directly guided to the reinforcing layer of semi-finished product 1 in the molten state, and then cooled to 20-25℃ after composite pressing to obtain semi-finished product 2. S4. The semi-finished product 2 is cured and then cut into sheets.

[0053] Preferably, in step S1, the method for preparing the high-gloss composite substrate layer comprises: performing a dry composite process on the PE layer, EPE layer, and CPE layer in sequence, followed by a second dry composite process with the VMPET layer, and then curing the resulting product.

[0054] Preferably, the specific steps of the one-time dry lamination are as follows: after applying polyurethane adhesive between each layer, the product is placed in an oven with a three-stage temperature gradient of 60-70℃, 75-85℃, and 90-100℃, a total drying time of 45-90s, a lamination pressure of 0.3-0.8MPa, and a lamination speed of 50-100m / min.

[0055] Preferably, the polyurethane adhesive is from Henkel, LIOFOL LA7705 / LA 6068, and can be used according to the instructions, with a coating amount of 2-5 g / m². 2 .

[0056] Preferably, the secondary dry lamination process is identical to the primary dry lamination process, except that: the oven temperature has three gradients: 50-60℃, 65-75℃, and 80-85℃; the total drying time is 45-90 seconds; the lamination pressure is 0.3-0.8 MPa; the lamination speed is 40-90 m / min; and the polyurethane adhesive coating amount is 3-6 g / m³. 2 .

[0057] Preferably, the specific conditions for the maturation are: a maturation temperature of 50-70℃ and a maturation time of 24-48h.

[0058] Preferably, in step S2, the mixing and melting temperature is 185-195℃, the die temperature for extrusion film formation is 170-180℃, and the die lip gap is 1.0-1.2mm.

[0059] Preferably, in step S2, the high-gloss composite substrate layer is preheated to 50-60°C before the composite roller.

[0060] Preferably, in step S2, the specific conditions for the composite pressure roller are: pressure of 6-8 kg / cm². 2 The temperature of the cooling roller is 15-20℃, and the linear speed is 80-100m / min.

[0061] Preferably, in step S3, the melting temperature of the adhesive layer material is 150-170℃, the melting temperature of the inner layer material is 190-200℃, the die temperature of the co-extrusion process is 180-190℃, and the die lip gap is 1.0-1.2mm.

[0062] Preferably, in step S3, the semi-finished product 1 is preheated to 70-90°C before the composite pressure roller.

[0063] Preferably, in step S3, the specific conditions for the composite pressure roller are: pressure of 6-8 kg / cm². 2 The temperature of the cooling roller is 25-35℃, and the linear speed is 80-100m / min.

[0064] Preferably, in step S4, the specific conditions for the aging process are: aging temperature of 60-80℃ and aging time of 48-72h.

[0065] First, a high-gloss composite substrate layer is prepared through dry lamination, and then the final sheet is obtained through multiple co-extrusion processes. This ensures that the VMPET layer is protected from heat damage, maintaining its gloss and barrier properties. This is likely because, on the one hand, controlling the temperature of the cooling rollers allows heat to be rapidly dissipated the instant the high-temperature melt comes into contact with the VMPET, causing the interface temperature to drop sharply below the safe threshold of the aluminum plating layer, fundamentally preventing oxidation of the aluminum layer. On the other hand, the gradient design of the temperature from low to high in the two dry lamination processes allows the solvent to evaporate smoothly from the inside out. This not only improves the flatness of the sheet, but the adjustment of the overall temperature range also protects the aluminum plating layer of the VMPET layer, reducing the risk of heat damage to the aluminum plating layer.

[0066] By co-extruding the adhesive layer and inner layer to form a composite melt curtain, and then pressing it with the reinforcing layer of semi-finished product 1, the interlayer peel force between the heat-sealing layer and the reinforcing layer can be improved, thereby enhancing the mechanical properties and lifespan of the sheet. This is likely because the processing temperatures of the three raw materials are different. If they were directly melt-co-extruded, it would lead to instability at the interlayer interface, affecting the sheet performance. However, by first extruding the reinforcing layer and composite it with the high-gloss substrate, ensuring thorough blending of metallocene-catalyzed polyethylene and HDPE without damaging the substrate, and then co-extruding the adhesive layer and inner layer to form a temperature gradient melt curtain, the adhesive layer penetrates into the micropores on the surface of the reinforcing layer, forming a dual bond of mechanical interlocking and chemical cross-linking, thus enhancing the interlayer peel force.

[0067] By employing a two-stage gradient curing process, not only can the interlayer strength of the sheet be improved, but also its interlayer strength stability. This is likely because the low-temperature curing stage in the preparation of the high-gloss composite substrate layer preferentially completes the local cross-linking of molecular chain segments, releasing some shrinkage stress, while preventing the aluminum plating layer from oxidizing at high temperatures. The second-stage medium-temperature curing provides sufficient energy to cause the adhesive molecules to move as a whole, releasing interlayer internal stress, while simultaneously promoting further reaction between the polar groups of the EMA and CPE layers, forming a denser cross-linked network. The stepwise temperature change allows the internal stress caused by the difference in the thermal expansion coefficients of the materials to be released in stages, preventing sheet warping and improving sheet flatness and performance stability.

[0068] By dividing the sheet into four functional layers—a high-gloss layer, a reinforcing layer, an adhesive layer, and an inner layer—and controlling the manufacturing method and the raw material composition and thickness of each layer, the mechanical strength and barrier properties of the sheet are balanced. The high-gloss layer provides appearance and basic barrier properties, the reinforcing layer provides mechanical support, the adhesive layer enables cross-layer connections, and the inner layer completes the heat-sealing function. These elements form a synergistic system at the microscopic level, ultimately giving the sheet a comprehensive performance that simultaneously possesses a metallic-like luster, high barrier properties, high strength, and strong interlayer bonding, fully meeting the high-end requirements of cosmetic, pharmaceutical, and food tube packaging.

[0069] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention provides a high-gloss multilayer co-extruded sheet for soft tube packaging. Through four functional layers—a high-gloss layer, a reinforcing layer, an adhesive layer, and an inner layer—and by controlling the preparation method and the raw material composition and thickness of each layer, the mechanical strength and barrier properties of the sheet are balanced. The high-gloss layer provides appearance and basic barrier properties, the reinforcing layer provides mechanical support, the adhesive layer achieves cross-layer connection, and the inner layer completes the heat-sealing function. These elements form a synergistic system at the microscopic level, ultimately enabling the sheet to simultaneously possess a metallic-like luster, high barrier properties, high strength, and strong interlayer bonding, fully meeting the high-end requirements of soft tube packaging for cosmetics, pharmaceuticals, and food.

[0070] 2. By designing a reinforcing layer, an adhesive layer, and an inner layer as the main structure of the sheet, and by controlling the raw materials and thickness of each layer, this invention can improve the mechanical properties and interlayer strength of the sheet, making the prepared sheet more suitable for use in flexible tube packaging.

[0071] 3. By designing PE layer, EPE layer, CPE layer and VMPET layer as high-gloss composite substrate layers and controlling the raw materials and thickness of each layer, this invention can improve the surface gloss and barrier effect of the sheet.

[0072] 4. The present invention first prepares a high-gloss composite substrate layer by dry lamination, and then prepares the final sheet by multiple co-extrusion laminations, which can ensure that the VMPET layer is not damaged by heat and maintain its gloss and barrier properties.

[0073] 5. By co-extruding the adhesive layer and inner layer to form a composite melt curtain, and then pressing it with the reinforcing layer of the semi-finished product 1, the present invention can improve the interlayer peel force between the heat-sealing layer and the reinforcing layer, thereby improving the mechanical properties and life of the sheet.

[0074] 6. By employing a two-stage gradient curing process, this invention can not only improve the interlayer strength of the sheet but also enhance the stability of the interlayer strength.

[0075] 7. This invention balances the mechanical strength and barrier properties of the sheet by dividing it into four functional layers: a high-gloss layer, a reinforcing layer, an adhesive layer, and an inner layer, and by controlling the preparation method and the raw material composition and thickness of each layer. Attached Figure Description

[0076] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0077] Figure 1 A photograph of the high-gloss multilayer co-extruded sheet for tube packaging prepared according to the present invention. Detailed Implementation

[0078] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0079] All raw materials used in this invention are commercially available, as detailed below: The PE raw material has a melt flow index of 0.5-0.7 g / 10 min and a density of 0.91-0.93 g / cm³ at 190℃. 3 From Westlake Corporation, linear low-density polyethylene resin LF74580.

[0080] The ethylene-acrylate copolymer contains 9% methyl acrylate and has an elongation at break of ≥700%. It is from DuPont, USA, and is 1609 AC.

[0081] Maleic anhydride-grafted polyethylene has a melt index of 5.5-6.5 g / 10 min at 190℃ and a maleic anhydride grafting rate of 1%-1.3%. It is from Dongguan Shenghao Plastic Raw Materials Co., Ltd., PE-12L.

[0082] The chlorinated polyethylene resin has a chlorine content of 34%-36% and an elongation at break of ≥600%, sourced from Yaxing Chemical, WEIPREN®RESIN, 6100.

[0083] The PET base film has a thickness of 12μm and is from Yihua Toray Polyester Film Co., Ltd., PET12.

[0084] Metallocene-catalyzed polyethylene exhibits a melt index of 1.0 g / 10 min and a density of 0.918 g / cm³ at 190 °C. 3 From ExxonMobil, ExxonMobil Exceed 1018CA.

[0085] HDPE has a melt index of 2.0 g / 10 min and a density of 0.954 g / cm³ at 190℃. 3From LyondellBasell, Lupolen 5261 Z.

[0086] The ionomer is an ethylene-methacrylic acid-based ionomer with a melt index of 2-4 g / 10 min at 190°C and an IZOD notched impact strength of 19-20 KJ / m at 23°C. It is sourced from DuPont, USA, using Surlyn® resin, 8940.

[0087] Polyurethane adhesive, from Henkel, LIOFOL LA7705 / LA 6068.

[0088] Example 1 This embodiment provides a high-gloss multilayer co-extruded sheet for tube packaging, the structure of which consists of a high-gloss composite substrate layer, a reinforcing layer, an adhesive layer, and an inner layer.

[0089] The thickness of the high-gloss composite substrate layer is 117 μm.

[0090] The thickness of the reinforcement layer is 100 μm.

[0091] The thickness of the adhesive layer is 20 μm.

[0092] The thickness of the inner layer is 145 μm.

[0093] The reinforcing layer is prepared from metallocene-catalyzed polyethylene and HDPE in a mass ratio of 1:1.4.

[0094] The adhesive layer is prepared from EMA and MAH-g-PE in a mass ratio of 7:3.

[0095] The inner layer is prepared from ionomers and antioxidants.

[0096] The antioxidant is antioxidant 1010, and the amount added is 0.5% of the mass of the ionomer.

[0097] The high-gloss composite substrate layer consists of a PE layer, an EPE layer, a CPE layer, and a VMPET layer, in sequence.

[0098] The thickness of the PE layer is 60 μm.

[0099] The thickness of the EPE layer is 20 μm.

[0100] The thickness of the CPE layer is 25 μm.

[0101] The VMPET layer has a thickness of 12 μm.

[0102] The method for preparing the PE layer includes the following steps: adding PE raw material into a casting machine for melting, extruding, and then cooling with a cooling roller to obtain the PE layer.

[0103] The melting temperature is 220℃, the cooling roller temperature is 20℃, and the traction speed is 90m / min.

[0104] The raw materials for preparing the EPE layer are the same as those for preparing the adhesive layer. The preparation method is as follows: mix EMA and MAH-g-PE, melt co-extrude, and then cast and cool to obtain the final product.

[0105] The specific conditions for the melt co-extrusion are: extruder temperature 190℃, die temperature 190℃, and screw speed 45rpm.

[0106] The specific conditions for casting cooling are: the temperature of the cooling roller is 25℃ and the traction speed is 15m / min.

[0107] The method for preparing the CPE layer includes the following steps: mixing CPE and additives at high speed, then extruding with a twin-screw extruder and calendering to obtain the final product.

[0108] The additives include calcium stearate and epoxidized soybean oil in a mass ratio of 1:2, and the total amount added is 1.5% of the mass of chlorinated polyethylene resin.

[0109] The specific conditions for high-speed mixing are: a rotation speed of 1000 rpm and a time of 10 min.

[0110] The specific conditions for the twin-screw extrusion are: temperature of 180℃, vacuum of 0.085MPa, and screw speed of 60rpm.

[0111] The specific conditions for calendering are: the temperature of the three-roll calender is 155℃ and the roll gap is 0.25mm.

[0112] The VMPET layer is prepared by pretreating the PET base film and then vacuum-depositing aluminum.

[0113] The pretreatment is a corona treatment, which is performed until the wetting tension of the PET base film surface is 50 dyn / cm.

[0114] The specific conditions for vacuum aluminum plating are as follows: the plating method is vapor deposition, and the vacuum degree is 8×10⁻⁶. -4 Pa, evaporation temperature of 1160℃, deposition rate of 16nm / s, aluminum layer thickness of 50nm.

[0115] The method for preparing the high-gloss multilayer co-extruded sheet for tube packaging comprises the following steps: S1. Prepare a high-gloss composite substrate layer; S2. Mix and melt the raw materials of the reinforcing layer, extrude them into a film, and then press the film with a high-gloss composite substrate layer. Cool the film to 20°C to obtain semi-finished product 1. S3. After the raw materials of the adhesive layer and the inner layer are melted and mixed separately, a composite melt curtain is formed by co-extrusion process. The melt curtain is directly guided to the reinforcing layer of semi-finished product 1 in the molten state, and then cooled to 20°C after composite pressing to obtain semi-finished product 2. S4. The semi-finished product 2 is cured and then cut into sheets.

[0116] In step S1, the preparation method of the high-gloss composite substrate layer is as follows: after the PE layer, EPE layer and CPE layer are dry-laminated once, they are dry-laminated again with the VMPET layer, and then cured to obtain the final product.

[0117] The specific steps of the one-time dry lamination are as follows: after applying polyurethane adhesive between each layer, the product is placed in an oven with a three-stage temperature gradient of 65℃, 80℃, and 95℃, a total drying time of 70s, a lamination pressure of 0.5MPa, and a lamination speed of 75m / min.

[0118] The coating amount of the polyurethane adhesive is 3.5 g / m². 2 .

[0119] The secondary dry lamination process is identical to the primary dry lamination process, with the only differences being: the oven temperature has three temperature gradients at 55℃, 70℃, and 82℃; the total drying time is 70 seconds; the lamination pressure is 0.35 MPa; the lamination speed is 75 m / min; and the polyurethane adhesive coating amount is 4.5 g / m³. 2 .

[0120] The specific conditions for maturation are: maturation temperature of 60℃ and maturation time of 36h.

[0121] In step S2, the mixing and melting temperature is 190°C, the die temperature for extrusion film formation is 175°C, and the die lip gap is 1.1 mm.

[0122] In step S2, the high-gloss composite substrate layer is preheated to 55°C before the composite pressure roller.

[0123] In step S2, the specific conditions for the composite pressure roller are: pressure of 7 kg / cm². 2 The temperature of the cooling roller is 18℃ and the linear speed is 90m / min.

[0124] In step S3, the melting temperature of the adhesive layer material is 160°C, the melting temperature of the inner layer material is 195°C, the die temperature of the co-extrusion process is 185°C, and the die lip gap is 1.1 mm.

[0125] In step S3, the semi-finished product 1 is preheated to 80°C before the composite pressure roller.

[0126] In step S3, the specific conditions for the composite pressure roller are: pressure of 7 kg / cm². 2 The temperature of the cooling roller is 30℃ and the linear speed is 90m / min.

[0127] In step S4, the specific conditions for the aging process are: aging temperature of 70℃ and aging time of 60h.

[0128] Example 2 The difference between this embodiment and Embodiment 1 is that the thickness of the high-gloss composite substrate layer is 122 μm.

[0129] The thickness of the PE layer is 65 μm.

[0130] The thickness of the EPE layer is 15 μm.

[0131] The thickness of the CPE layer is 30 μm.

[0132] The VMPET layer has a thickness of 12 μm.

[0133] Comparative Example 1 The difference between this comparative example and Example 1 is that the high-gloss multilayer co-extruded sheet used for tube packaging has a structure consisting of a high-gloss composite substrate layer, a reinforcing layer, and an inner layer.

[0134] The thickness of the high-gloss composite substrate layer is 117 μm.

[0135] The thickness of the reinforcement layer is 110 μm.

[0136] The thickness of the inner layer is 155 μm.

[0137] Comparative Example 2 The difference between this comparative example and Example 1 is that the raw material for preparing the reinforcing layer is metallocene-catalyzed polyethylene.

[0138] Comparative Example 3 The difference between this comparative example and Example 1 is that the raw material for preparing the adhesive layer is EMA.

[0139] Comparative Example 4 The difference between this comparative example and Example 1 is that the PE raw material has a melt flow index of 1.7-2.3 g / 10 min at 190°C and a density of 0.9205-0.9245 g / cm³. 3 , from Yanshan Petrochemical, LDPE / LD100AC.

[0140] Comparative Example 5 The difference between this comparative example and Example 1 is that in step A2, the specific conditions for vacuum aluminum plating are: the plating method is vapor deposition, and the vacuum degree is 6 × 10⁻⁶. -4Pa, evaporation temperature is 1150℃, deposition rate is 15nm / s, and aluminum layer thickness is 30nm.

[0141] Comparative Example 6 The difference between this comparative example and Example 1 is that the high-gloss composite substrate layer consists of a PE layer, an EPE layer, a CPE layer, and a VMPET layer in sequence.

[0142] The thickness of the PE layer is 70 μm.

[0143] The thickness of the EPE layer is 20 μm.

[0144] The thickness of the CPE layer is 15 μm.

[0145] The VMPET layer has a thickness of 12 μm.

[0146] Comparative Example 7 The difference between this comparative example and Example 1 is that the preparation method of the high-gloss multilayer co-extruded sheet for tube packaging includes the following steps: S1. Prepare a high-gloss composite substrate layer; S2. After melting the raw materials of the reinforcing layer, adhesive layer and inner layer respectively, a composite melt curtain is formed by co-extrusion process, which is then combined with a high-gloss composite substrate layer and pressed with a pressure roller. After cooling to 20°C, semi-finished product 1 is obtained. S3. The semi-finished product 1 is cured and then cut into sheets.

[0147] In step S2, the melting temperature of the reinforcing layer material is 190°C, the melting temperature of the adhesive layer material is 160°C, the melting temperature of the inner layer material is 195°C, the die temperature of the co-extrusion process is 185°C, and the die lip gap is 1.1 mm.

[0148] Comparative Example 8 The difference between this comparative example and Example 1 is that in step S1, the specific steps of the one-time dry lamination are as follows: after applying polyurethane adhesive between each layer, the product is sent into an oven at a temperature of 80°C, with a total drying time of 70 seconds, a lamination pressure of 0.5 MPa, and a lamination speed of 75 m / min.

[0149] Comparative Example 9 The difference between this comparative example and Example 1 is that in step S2, the secondary dry composite process is the same as the primary dry composite process.

[0150] Comparative Example 10 The difference between this comparative example and Example 1 is that in step S1, the preparation method of the high-gloss composite substrate layer is as follows: after the PE layer, EPE layer and CPE layer are dry-laminated once, they are dry-laminated again with the VMPET layer to obtain the final product.

[0151] Performance testing The haze of the sheet was tested according to the method in GB / T 2410-2008, %; the gloss at 60° of the sheet was tested according to the method in GB / T 8807-1988; the oxygen transmittance of the sheet was tested according to the method in GB / T 19789-2005, cm. 3 / (m 2 •24h); The water vapor transmission rate of the sheet was tested according to the method in GB / T 1037-1988, g / (m 2 • 24h); The interlayer peel strength of the reinforcing layer / inner layer in the sheet was tested according to the method in GB / T8808-1988, N / 15mm; The tensile strength and elongation at break of the sheet were tested according to the method in GB / T 1040.3-2006, with units of N / 15mm and %, respectively. The results are shown in Table 1.

[0152] Table 1 Measurement Results According to statistics, the high-gloss multilayer co-extruded sheets for soft tube packaging prepared in Examples 1-2 of this invention have low haze, high gloss, low oxygen and water vapor permeability, excellent barrier properties, high interlayer peel strength, excellent mechanical properties, and good toughness, making them suitable for soft tube packaging. Comparative Example 1 did not add an adhesive layer; Comparative Example 2's reinforcing layer was prepared using only metallocene-catalyzed polyethylene; Comparative Example 3's adhesive layer was prepared using only EMA; Comparative Example 4's PE raw material was ordinary low-density polyethylene, with low permeability; Comparative Example 5's aluminum layer thickness was too low; Comparative Example 6's CPE layer thickness was too low; Comparative Example 7 was a single co-extrusion; Comparative Example 8's single dry lamination did not use segmented drying; Comparative Example 9's secondary dry lamination followed the same steps as the single dry lamination, but the drying temperature was too high; Comparative Example 10 did not cure in step S1, resulting in sheets with various defects and deficiencies in their properties. Therefore, the multilayer co-extruded sheet prepared using the raw materials and methods described in this application has high gloss, excellent barrier properties, and good mechanical and heat-sealing properties. It is suitable for tube packaging and can be applied in cosmetics, pharmaceuticals, food and other fields, with broad market application prospects.

[0153] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high gloss multilayer co-extruded sheet for hose packaging, characterized in that, Its structure consists of, in sequence, a high-gloss composite substrate layer, a reinforcing layer, an adhesive layer, and an inner layer; the high-gloss composite substrate layer consists of, in sequence, a PE layer, an EPE layer, a CPE layer, and a VMPET layer; the reinforcing layer is prepared from metallocene-catalyzed polyethylene and HDPE; the metallocene-catalyzed polyethylene has a melt index of 1.0 g / 10 min and a density of 0.918 g / cm³ at 190°C. 3 The HDPE has a melt flow index of 2.0 g / 10 min and a density of 0.954 g / cm³ at 190°C. 3 The mass ratio of the metallocene-catalyzed polyethylene to HDPE is 1:(1-1.8).

2. High gloss multilayer co-extruded sheet for hose packaging according to claim 1, characterized in that, The thickness of the high-gloss composite substrate layer is 100-135 μm; the thickness of the reinforcing layer is 90-110 μm; the thickness of the adhesive layer is 15-25 μm; and the thickness of the inner layer is 130-160 μm.

3. The high gloss multilayer co-extruded sheet for hose packaging according to claim 1, characterized in that, The raw materials for preparing the adhesive layer include EMA and MAH-g-PE; the MA content in the EMA is 9%, and the elongation at break is ≥700%; the melt index of the MAH-g-PE at 190 ℃ is 5.5-6.5 g / 10 min, and the MAH grafting rate is 1%-1.3%; and the mass ratio of the EMA to the MAH-g-PE is (2-3):

1.

4. The high gloss multilayer co-extruded sheet for hose packaging according to claim 1, characterized in that, The raw materials for preparing the inner layer include an ionic polymer and an antioxidant; the ionic polymer is an ethylene-methacrylic acid-based ionic polymer, the melt index of which at 190 ℃ is 2-4 g / 10 min, and the IZOD notched impact strength at 23 ℃ is 19-20 KJ / m.

5. The high gloss multilayer co-extruded sheet for hose packaging according to claim 2, characterized in that, The thickness of the PE layer is 55-65 μm; the thickness of the EPE layer is 15-25 μm; the thickness of the CPE layer is 20-30 μm; and the thickness of the VMPET layer is 10-15 μm.

6. A process for the production of a high gloss multilayer co-extruded sheet for the packaging of hoses according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, preparing a high-gloss composite substrate layer; S2, mixing and melting the raw materials of the reinforcing layer, extruding a film, and compounding and rolling with the high-gloss composite substrate layer to obtain semi-product 1 after cooling to 20-25 ℃; S3, mixing and melting the raw materials of the adhesive layer and the inner layer respectively, forming a composite melt curtain through a co-extrusion process, and directly guiding the composite melt curtain to the reinforcing layer of the semi-product 1 in a molten state to obtain semi-product 2 after compounding and rolling and cooling to 20-25 ℃; and S4, aging the semi-product 2 and cutting to obtain a sheet.

7. Process for the production of a high-gloss multilayer co-extruded sheet for hose packaging according to claim 6, characterized in that, In the step S1, the high-gloss composite substrate layer is prepared by the following steps: sequentially performing one-time dry compounding on the PE layer, the EPE layer and the CPE layer, and then performing two-time dry compounding on the VMPET layer, and aging to obtain the high-gloss composite substrate layer.

8. Process for the production of a high-gloss multilayer co-extruded sheet for hose packaging according to claim 7, characterized in that, The specific steps of the one-time dry compounding are as follows: coating polyurethane adhesive in the middle of each layer, feeding into an oven, setting the oven temperature to three-stage gradient, i.e. 60-70 ℃, 75-85 ℃ and 90-100 ℃, setting the total drying time to 45-90 s, setting the compounding pressure to 0.3-0.8 MPa, and setting the compounding speed to 50-100 m / min.

9. Process for the production of a high-gloss multilayer co-extruded sheet for hose packaging according to claim 8, characterized in that, The secondary dry compounding is consistent with the primary dry compounding, and the difference is only that the oven temperature is three-stage gradient, which is 50-60℃, 65-75℃ and 80-85℃ respectively, the total drying time is 45-90s, the compounding pressure is 0.3-0.8MPa, the compounding speed is 40-90m / min, and the polyurethane adhesive coating amount is 3-6g / m 2 .

10. Process for the production of a high-gloss multilayer co-extruded sheet for hose packaging according to claim 7, characterized in that, The specific conditions of the aging are as follows: setting the aging temperature to 50-70 ℃, and setting the aging time to 24-48 h.

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