High barrier recyclable laminated film and preparation method thereof

Abstract

The present application discloses a high-barrier polyolefin composite film, including, from the outside to the inside, an outer PE film, a water-barrier layer, a high-barrier PVA coating layer, an adhesive layer, and an inner PE film, wherein the inner PE film comprises the following raw materials in percentage by weight: 10-20% of HDPE, 30-50% of MDPE, 20-26% of LLDPE, 10-20% of LDPE, 8-12% of a water- and oxygen-barrier masterbatch, and 1-3% of an auxiliary agent; the water- and oxygen-barrier masterbatch includes the following raw materials in parts by weight: 10-20 parts of polycarbonate, 0.1-0.3 parts of a compatibilizer, 10-20 parts of an ethylene-vinyl acetate copolymer (EVA), 1-2 parts of single-layer graphene, and 1-2 parts of polyhedral oligomeric silsesquioxane.

Claims

1. A polyolefin composite film, comprising, from outside to inside, an outer film, a water-barrier layer, a polyvinyl alcohol coating layer, an adhesive layer, and an inner film, wherein the outer film is an outer polyethylene film, and the inner film is a modified inner polyethylene film; the modified inner polyethylene film comprises the following raw materials in percentage by weight: 10-20% of high-density polyethylene, 30-50% of medium-density polyethylene, 20-26% of linear low-density polyethylene, 10-20% of low-density polyethylene, 8-12% of a water- and oxygen-barrier masterbatch, and 1-3% of an auxiliary agent; and the water- and oxygen-barrier masterbatch comprises the following raw materials in parts by weight: 10-20 parts of polycarbonate, 0.1-0.3 parts of a compatibilizer, 10-20 parts of an ethylene-vinyl acetate copolymer, 1-2 parts of single-layer graphene, and 1-2 parts of polyhedral oligomeric silsesquioxane.

2. The polyolefin composite film according to claim 1, wherein the water- and oxygen-barrier masterbatch is prepared as follows: hot-melting the ethylene-vinyl acetate copolymer, adding the polyhedral oligomeric silsesquioxane and the single-layer graphene purified with concentrated nitric acid to melted ethylene-vinyl acetate copolymer, dispersing the melted ethylene-vinyl acetate copolymer ultrasonically for 1-2 h, and drying the melted ethylene-vinyl acetate copolymer to constant weight at 50-60? C. to obtain modified single-layer graphene; and mixing the modified single-layer graphene with the polycarbonate and the compatibilizer and performing melting, extruding and granulating, and drying.

3. The polyolefin composite film according to claim 1, wherein the compatibilizer comprises maleic anhydride-grafted low-density polyethylene and maleic anhydride-grafted ethylene-vinyl acetate at a mass ratio of 1:0.3-0.5.

4. The polyolefin composite film according to claim 1, wherein the polyvinyl alcohol coating layer is formed from a polyvinyl alcohol coating solution, and preparation of the polyvinyl alcohol coating solution comprises the following steps: dissolving a carboxylated cellulose nanofiber to prepare a solution with a concentration of 0.8-1 wt % of the carboxylated cellulose nanofiber, adding chitosan to the solution, performing ultrasonic dispersion, freeze-drying and pulverizing to obtain an airgel powder; dissolving tannic acid to prepare a tannic acid solution with a concentration of 2-4 wt % of the tannic acid, immersing the airgel powder in the tannic acid solution for 5-10 min, and washing to obtain a modified airgel powder; and dissolving polyvinyl alcohol to prepare an aqueous solution of polyvinyl alcohol with a concentration of 5-7 wt % of the polyvinyl alcohol, adding the modified airgel powder and octadecyltrichlorosilane to the aqueous solution, and mixing evenly to obtain the polyvinyl alcohol coating solution.

5. The polyolefin composite film according to claim 4, wherein the polyvinyl alcohol coating solution comprises the following raw materials in parts by weight: 1.5-2.2 parts of the polyvinyl alcohol, 1-1.2 parts of the carboxylated cellulose nanofiber, 0.8-1.2 parts of the chitosan, 0.4-0.6 parts of the tannic acid, and 1-1.5 parts of the octadecyltrichlorosilane.

6. The polyolefin composite film according to claim 1, wherein the water-barrier layer is formed by hot-melting and curing a water-barrier adhesive and the water-barrier adhesive is prepared as follows: by weight, mixing 1-2 parts of polydimethylsiloxane, 10-20 parts of n-hexane and 0.1-0.2 parts of a polydimethylsiloxane curing agent evenly to obtain a mixture, adding 0.5-1 part of hydrophobic nano-silica to the mixture, mixing the mixture evenly, drying the mixture at 80-90? C. for 1-2 h, and ultrafinely pulverizing the mixture to obtain an intermediate; and mixing the intermediate with 4-8 parts of ethylene-vinyl acetate resin evenly to obtain the water-barrier adhesive.

7. The polyolefin composite film according to claim 1, wherein the adhesive layer is formed by curing an adhesive, and the adhesive is one selected from a group consisting of a polyurethane adhesive, an epoxy resin adhesive, and an acrylic resin adhesive.

8. The polyolefin composite film according to claim 1, wherein a thickness ratio of the outer polyethylene film to the modified inner polyethylene film is 1-1.5:1.

9. A preparation method of the polyolefin composite film according to claim 1, comprising the following steps: performing corona treatment on an inner side of the outer film to obtain a corona-treated side of the outer film, heating a water-barrier adhesive to 50-55? C. to obtain a heated water-barrier adhesive, applying the heated water-barrier adhesive onto the corona-treated side of the outer film, and drying the heated water-barrier adhesive to form the water-barrier layer on the outer film; applying a polyvinyl alcohol coating solution onto a surface of the water-barrier layer and drying the polyvinyl alcohol coating solution to form the polyvinyl alcohol coating layer on the water-barrier layer; and applying a layer of adhesive onto the polyvinyl alcohol coating layer by using a brush roller at a temperature of 35-50? C., and combining the inner film on the adhesive by using a hot-press roller at a temperature of 35-50? C. to obtain a combined film; and performing cooling, drawing, winding up, and aging on the combined film to obtain the polyolefin composite film.

10. The preparation method of the polyolefin composite film according to claim 9, wherein an application amount of the water-barrier adhesive is 1-3 g/m.sup.2, an application amount of the polyvinyl alcohol coating solution is 2-6 g/m.sup.2, and an application amount of the adhesive is 1.2-4 g/m.sup.2.

Description

DETAILED DESCRIPTION

(1) The present application will be further described in detail below with reference to embodiments.

Preparation Examples 1-7 of Water- and Oxygen-Barrier Masterbatch

(2) In Preparation Example 1, EVA used was US DuPont EVA 40W, with a melt index of 52 g/10 min (190? C., 2.16 kg), a density of 0.965 g/cm.sup.3 and VA content of 40%, purchased from Kuraray Co., Ltd. (Japan); octaisobutyl polysesquioxane (product number: 9502019) used was purchased from Forsman Technology (Beijing) Co., Ltd.; single-layer graphene (model: TGF-I) used was purchased from Everoot (Xiamen) Graphene Technology Co., Ltd.; polypropylene carbonate (model: PPC-001) used was purchased from Wuhan Lullaby Pharmaceutical Chemical Co., Ltd.; maleic anhydride-grafted LDPE (model: E528) was purchased from Shanghai Xinkaili Plastic Technology Co., Ltd.; maleic anhydride-grafted ethylene-vinyl acetate (model: SH-112A) used was purchased from Dongguan Zhangmutou Hengtai Plastic Raw Materials Co., Ltd.; and maleic anhydride grafted POE (model: EB-3008) was purchased from Guangzhou Chuanju Chemical Technology Co., Ltd.

(3) Preparation Example 1: 20 g of EVA was heated to 80? C., stirred and melted, 2 g of polyhedral oligomeric silsesquioxane and 2 g of single-layer graphene purified with concentrated nitric acid were added to the melted EVA and dispersed ultrasonically for 2 h, and the mixture was then dry to constant weight at 60? C. to obtain modified single-layer graphene. The polyhedral oligomeric silsesquioxane used was octaisobutyl polysesquioxane. The single-layer graphene was purified with concentrated nitric acid as follows: the single-layer graphene was mixed with 3 mol/L concentrated nitric acid, dispersed ultrasonically in a 80? C. water bath with stirring for 8 h, and then cooled to room temperature, filtered with suction, and washed with deionized water until the pH value of the filtrate was centered, and finally dried at 120? C.

(4) The modified single-layer graphene was mixed with 20 g of polycarbonate and 0.3 g of a compatibilizer, and the mixture was then melted, extruded and granulated, and dried. The compatibilizer included maleic anhydride-grafted LDPE and maleic anhydride-grafted ethylene-vinyl acetate at a mass ratio of 1:0.5, and the polycarbonate was polypropylene carbonate made by the copolymerization of carbon dioxide and propylene oxide.

(5) Preparation Example 2: 10 g of EVA was heated to 80? C., stirred and melted, 1 g of polyhedral oligomeric silsesquioxane and 1 g of single-layer graphene purified with concentrated nitric acid were added to the melted EVA and dispersed ultrasonically for 1 h, and the mixture was then dry to constant weight at 50? C. to obtain modified single-layer graphene. The polyhedral oligomeric silsesquioxane used was octaisobutyl polysesquioxane. The single-layer graphene was purified with concentrated nitric acid as follows: the single-layer graphene was mixed with 3 mol/L concentrated nitric acid, dispersed ultrasonically in a 80? C. water bath with stirring for 8 h, and then cooled to room temperature, filtered with suction, and washed with deionized water until the pH value of the filtrate was centered, and finally dried at 120? C.

(6) The modified single-layer graphene was mixed with 10 g of polycarbonate and 0.1 g of a compatibilizer, and the mixture was then melted, extruded and granulated, and dried. The compatibilizer included maleic anhydride-grafted LDPE and maleic anhydride-grafted ethylene-vinyl acetate at a mass ratio of 1:0.3, and the polycarbonate was polypropylene carbonate made by the copolymerization of carbon dioxide and propylene oxide.

(7) Preparation Example 3: The compatibilizer used in this preparation example was maleic anhydride-grafted LDPE, which is different from Preparation Example 1.

(8) Preparation Example 4: The compatibilizer used in this preparation example was maleic anhydride-grafted POE, which is different from Preparation Example 1.

(9) Preparation Example 5: No EVA was added in this preparation example, which is different Preparation Example 1.

(10) Preparation Example 6: No single-layer graphene was added in this preparation example, which is different Preparation Example 1.

(11) Preparation Example 7: No polyhedral oligomeric silsesquioxane was added in this preparation example, which is different Preparation Example 1.

Preparation Examples 8-12 of High-Barrier PVA Coating Solution

(12) In Preparation Example 8, carboxylated cellulose nanofiber used was purchased from Macklin, with a diameter of 50 nm and a length of 1 ?m, and chitosan used was purchased from Macklin, with a deacetylation degree of ?95%.

(13) Preparation Example 8: 1.2 g of a carboxylated cellulose nanofiber was dissolved in water to prepare an aqueous solution with a concentration of 1 wt %, 1.2 g of chitosan was added and dispersed ultrasonically at a power of 200 W for 20 min, and the mixture was then freeze-dried at ?60? C. for 24 h and pulverized to obtain an airgel powder.

(14) 0.4 g of tannic acid was dissolved in distilled water to prepare a tannic acid solution with a concentration of 4 wt %, and the airgel powder prepared was immersed in the tannic acid solution for 10 min and then washed with deionized water to obtain a modified airgel powder.

(15) 2.2 g of polyvinyl alcohol 1788 was dissolved in distilled water to prepare an aqueous solution of polyvinyl alcohol with a concentration of 7 wt %, the modified airgel powder prepared and 1.5 g of octadecyltrichlorosilane were added, and the resulting solution was mixed adequately to obtain a high-barrier PVA coating solution.

(16) Preparation Example 9: 1.0 g of a carboxylated cellulose nanofiber was dissolved in water to prepare an aqueous solution with a concentration of 0.8 wt %, 0.8 g of chitosan was added and dispersed ultrasonically at a power of 200 W for 20 min, and the mixture was then freeze-dried at ?60? C. for 24 h and pulverized to obtain an airgel powder.

(17) 0.6 g of tannic acid was dissolved in distilled water to prepare a tannic acid solution with a concentration of 2 wt %, and the airgel powder prepared was immersed in the tannic acid solution for 5 min and then washed with deionized water to obtain a modified airgel powder.

(18) 1.5 g of polyvinyl alcohol 1788 was dissolved in distilled water to prepare an aqueous solution of polyvinyl alcohol with a concentration of 5 wt %, the modified airgel powder prepared and 1.0 g of octadecyltrichlorosilane were added and the resulting solution was mixed adequately to obtain a high-barrier PVA coating solution.

(19) Preparation Example 10: No chitosan was added in this preparation example, which is different Preparation Example 8.

(20) Preparation Example 11: No octadecyltrichlorosilane was added in this preparation example, which is different Preparation Example 8.

(21) Preparation Example 12: 1.2 g of a carboxylated cellulose nanofiber was dissolved to prepare a solution with a concentration of 1 wt %, 1.2 g of chitosan was added and dispersed ultrasonically at a power of 200 W for 20 min, and the mixture was then freeze-dried at ?60? C. for 24 h and pulverized to obtain an airgel powder.

(22) 2.2 g of polyvinyl alcohol 1788 was dissolved in distilled water to prepare an aqueous solution of polyvinyl alcohol with a concentration of 7 wt %, the airgel powder prepared and 1.5 g of octadecyltrichlorosilane were added, and the resulting solution was mixed adequately to obtain a high-barrier PVA coating solution.

Preparation Examples 13-16 of Water-Barrier Adhesive

(23) In Preparation Example 13, EVA resin used was US DuPont EVA 40W, with a melt index of 52 g/10 min (190? C., 2.16 kg), a density of 0.965 g/cm.sup.3 and VA content of 40%, purchased from Kuraray Co., Ltd. (Japan); polydimethylsiloxane (model: PMA-200 500CS) used was purchased from Guangzhou Shengrui Chemical Technology Co., Ltd.; the PDMS curing agent used was Dow Corning DC184; and hydrophobic nanosilica (model: SS-S10B) used was purchased from Hangzhou Jikang New Materials Co., Ltd.

(24) Preparation Example 13: 2 g of polydimethylsiloxane, 20 g of n-hexane and 0.2 g of the PDMS curing agent were mixed together, 1 g of hydrophobic nano-silica was then added, and the mixture was mixed adequately and then dried at 90? C. for 1 h and ultrafinely pulverized to obtain an 2 ?m intermediate; and the intermediate was then mixed with 8 g of EVA resin adequately to obtain a water-barrier adhesive. The particle size of the silica used was 30 nm.

(25) Preparation Example 14: 1 g of polydimethylsiloxane, 10 g of n-hexane and 0.1 g of the PDMS curing agent were mixed together, 0.5 g of hydrophobic nano-silica was then added, and the mixture was mixed adequately and then dried at 80? C. for 2 h and ultrafinely pulverized to obtain an 2 ?m intermediate; and the intermediate was then mixed with 4 g of EVA resin adequately to obtain a water-barrier adhesive. The particle size of the silica used was 30 nm.

(26) Preparation Example 15: No hydrophobic nano-silica was added in this preparation example, which is different Preparation Example 13.

(27) Preparation Example 16: No polydimethylsiloxane was added in this preparation example, which is different Preparation Example 13.

Examples

(28) In Example 1, HDPE (product number: HHM5502LW) used was purchased from Sinopec Maoming Petrochemical Company; MDPE (brand: HF513) used was purchased from Total; LLDPE (brand: DFDA-7042) used was purchased from Sinopec Maoming Petrochemical Company; LDPE (model: 2426K) used was purchased from Sinopec Maoming Petrochemical Company; polyurethane adhesive (model: XH-66F) used was purchased from Guangdong Xinhui Chemical Co., Ltd.; EVA resin used was US DuPont EVA 40W, with a melt index of 52 g/10 min (190? C., 2.16 kg), a density of 0.965 g/cm.sup.3 and VA content of 40%, purchased from Kuraray Co., Ltd. (Japan).

(29) Example 1: This example provided a high-barrier polyolefin composite film, including, from the outside to the inside, an outer PE film, a water-barrier layer, a high-barrier PVA coating layer, an adhesive layer, and a modified inner PE film. The outer PE film having a thickness of 0.02 mm was purchased from Cangzhou Yongsheng Plastic Industry Co., Ltd., with a product number of XH001. The thickness of the modified inner PE film was 0.02 mm. The use amounts of raw materials of the modified inner PE film are shown in Table 1, where the water- and oxygen-barrier masterbatch was prepared according to Preparation Example 1, and the auxiliary agent was antioxidant 1010.

(30) A preparation method of the high-barrier polyolefin composite film described above included the following steps:

(31) In S1, corona treatment was performed on an inner side of the outer PE film, where the power of the corona treatment was 3 KW; the water-barrier adhesive was heated to 50? C. to be hot-melted, and the hot-melted water-barrier adhesive was then applied onto the corona-treated side of the outer PE film and dried to form the water-barrier layer on the outer PE film, where the water-barrier adhesive was EVA resin, and the application amount of the water-barrier adhesive was 3 g/m.sup.2.

(32) In S2, the high-barrier PVA coating solution was applied onto the surface of the water-barrier layer and then dried to form a high-barrier PVA coating layer on the water-barrier layer. The high-barrier PVA coating solution was prepared as follows: dissolving 2.2 g of polyvinyl alcohol 1788 in distilled water to prepare an aqueous solution of polyvinyl alcohol with a concentration of 7 wt %. The application amount of the high-barrier PVA coating solution was 6 g/m.sup.2.

(33) In S3, the raw materials of the modified inner PE film were mixed according to their use amounts shown in Table 1 and melted, extruded, and blow-molded to obtain the PE inner film, where the extrusion temperature was 160? C., the blowup ratio was 3, and the traction ratio was 4.

(34) In S4, a layer of the adhesive was applied onto the high-barrier PVA coating layer by using a brush roller with a temperature of 50? C., the modified inner PE film was combined on the adhesive by using a hot-press roller with a temperature of 50? C., and the combined film was cooled, drawn, wound up, and aged to obtain the high-barrier polyolefin composite film, where the pressure of the hot-press roller was 0.3 MPa, the pressing time is 0.5 mm/min, the adhesive was a polyurethane adhesive, the application amount of the adhesive was 4 g/m.sup.2, and the combined film was aged at 35? C. for 12 h.

(35) TABLE-US-00001 TABLE 1 Use amounts of raw materials of the modified inner PE film in high-barrier polyolefin composite films in Example 1-4 Raw material/kg Example 1 Example 2 Example 3 Example 4 HDPE 12 16 11 20 MDPE 35 30 50 30 LLDPE 24 20 20 26 LDPE 15 20 10 12 Water-and 12 11 8 10 oxygen-barrier masterbatch Auxiliary agent 2 3 1 2

(36) Example 2: This example provided a high-barrier polyolefin composite film, including, from the outside to the inside, an outer PE film, a water-barrier layer, a high-barrier PVA coating layer, an adhesive layer, and a modified inner PE film. The outer PE film (product number: XH001) having a thickness of 0.015 mm was purchased from Cangzhou Yongsheng Plastic Industry Co., Ltd. The thickness of the modified inner PE film was 0.01 mm. The use amounts of raw materials of the modified inner PE film are shown in Table 1, where the water- and oxygen-barrier masterbatch was prepared according to Preparation Example 2.

(37) A preparation method of the high-barrier polyolefin composite film described above included the following steps:

(38) In S1, corona treatment was performed on an inner side of the outer PE film, where the power of the corona treatment was 5 KW; the water-barrier adhesive was heated to 55? C. to be hot-melted, and the hot-melted water-barrier adhesive was then applied onto the corona-treated side of the outer PE film and dried to form the water-barrier layer on the outer PE film, where the water-barrier adhesive was EVA resin, and the application amount of the water-barrier adhesive was 1 g/m.sup.2.

(39) In S2, the high-barrier PVA coating solution was applied onto the surface of the water-barrier layer and then dried to form a high-barrier PVA coating layer on the water-barrier layer. The high-barrier PVA coating solution was prepared as follows: dissolving 2.2 g of polyvinyl alcohol 1788 in distilled water to prepare an aqueous solution of polyvinyl alcohol with a concentration of 7 wt %. The application amount of the high-barrier PVA coating solution was 2 g/m.sup.2.

(40) In S3, the raw materials of the modified inner PE film were mixed according to their use amounts shown in Table 1 and melted, extruded, and blow-molded to obtain the modified inner PE film, where the extrusion temperature was 160? C., the blowup ratio was 3, and the traction ratio was 4.

(41) In S4, a layer of the adhesive was applied onto the high-barrier PVA coating layer by using a brush roller with a temperature of 50? C., the modified inner PE film was combined on the adhesive by using a hot-press roller with a temperature of 50? C., and the combined film was cooled, drawn, wound up, and aged to obtain the high-barrier polyolefin composite film, where the pressure of the hot-press roller was 0.3 MPa, the pressing time is 0.5 mm/min, the adhesive was a polyurethane adhesive, the application amount of the adhesive was 1.2 g/m.sup.2, and the combined film was aged at 35? C. for 12 h.

(42) Examples 3-4: Examples 3-4 provided a high-barrier polyolefin composite film. Examples 3-4 differ from Example 1 in the use amounts of the raw materials of the modified inner PE film, as shown in Table 1.

(43) Example 5: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the water- and oxygen-barrier masterbatch in the modified inner PE film was prepared according to Preparation Example 3.

(44) Example 6: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the water- and oxygen-barrier masterbatch in the modified inner PE film was prepared according to Preparation Example 4.

(45) Example 7: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the high-barrier PVA coating solution was prepared according to Preparation Example 8.

(46) Example 8: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the high-barrier PVA coating solution was prepared according to Preparation Example 9.

(47) Example 9: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the high-barrier PVA coating solution was prepared according to Preparation Example 10.

(48) Example 10: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the high-barrier PVA coating solution was prepared according to Preparation Example 11.

(49) Example 11: This example provided a high-barrier polyolefin composite film. This example differs from Example 1 in that the high-barrier PVA coating solution was prepared according to Preparation Example 12.

(50) Example 12: This example provided a high-barrier polyolefin composite film. This example differs from Example 7 in that the water-barrier adhesive was prepared according to Preparation Example 13.

(51) Example 13: This example provided a high-barrier polyolefin composite film. This example differs from Example 7 in that the water-barrier adhesive was prepared according to Preparation Example 14.

(52) Example 14: This example provided a high-barrier polyolefin composite film. This example differs from Example 12 in that the water-barrier adhesive was prepared according to Preparation Example 15.

(53) Example 15: This example provided a high-barrier polyolefin composite film. This example differs from Example 12 in that the water-barrier adhesive was prepared according to Preparation Example 16.

(54) Example 16: This example provided a high-barrier polyolefin composite film, including, from the outside to the inside, an outer PP film, a water-barrier layer, a high-barrier PVA coating layer, an adhesive layer, and an inner PP film. The outer PP film and the inner PP film were 0.02 mm in thickness and were purchased from Wenzhou Ruowang Packaging Materials Co., Ltd., with a product number of D05.

(55) A preparation method of the high-barrier polyolefin composite film described above included the following steps:

(56) In S1, corona treatment was performed on an inner side of the outer PP film, where the power of the corona treatment was 3 KW; the water-barrier adhesive was heated to 50? C. to be hot-melted, and the hot-melted water-barrier adhesive was then applied onto the corona-treated side of the outer PP film and dried to form the water-barrier layer on the outer PP film, where the water-barrier adhesive was prepared according to Preparation Example 13, and the application amount of the water-barrier adhesive was 3 g/m.sup.2.

(57) In S2, the high-barrier PVA coating solution was applied onto the surface of the water-barrier layer and then dried to form a high-barrier PVA coating layer on the water-barrier layer. The high-barrier PVA coating solution was prepared according to Preparation Example 8, and the application amount of the high-barrier PVA coating solution was 6 g/m.sup.2.

(58) In S3, a layer of the adhesive was applied onto the high-barrier PVA coating layer by using a brush roller with a temperature of 50? C., the inner PP film was combined on the adhesive by using a hot-press roller with a temperature of 50? C., and the combined film was cooled, drawn, wound up, and aged to obtain the high-barrier polyolefin composite film, where the pressure of the hot-press roller was 0.3 MPa, the pressing time is 0.5 mm/min, the adhesive was a polyurethane adhesive (Model: XH-66F), purchased from Guangdong Xinhui Chemical Co., Ltd., the application amount of the adhesive was 4 g/m.sup.2, and the combined film was aged at 35? C. for 12 h.

Comparative Examples

(59) Comparative Example 1: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that the water- and oxygen-barrier masterbatch was prepared according to Preparation Example 5.

(60) Comparative Example 2: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that the water- and oxygen-barrier masterbatch was prepared according to Preparation Example 6.

(61) Comparative Example 3: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that the water- and oxygen-barrier masterbatch was prepared according to Preparation Example 7.

(62) Comparative Example 4: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that no water- and oxygen-barrier masterbatch was added.

(63) Comparative Example 5: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that no high-barrier PVA coating solution was provided.

(64) Comparative Example 6: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that no water-barrier layer was provided.

(65) Comparative Example 7: This comparative example provided a high-barrier polyolefin composite film. This comparative example differs from Example 1 in that the PE inner film was purchased from Cangzhou Yongsheng Plastic Industry Co., Ltd., with a product number of XH001, and its thickness was 0.02 mm.

(66) Comparative Example 8: This comparative example provided an antibacterial high-oxygen-barrier PE composite film, including a PE film and a PVA film. The PE film included the following raw materials in parts by weight: 100 parts of linear low-density polyethylene, 5 parts of low-density polyethylene, 5 parts of low-density PE-g-MAH, and 12 parts of an antibacterial and antistatic additive. The PVA film included the following raw materials in parts by weight: 100 parts of polyvinyl alcohol resin, 4 parts of silicone oil, 3 parts of propylene glycol, 45 parts of polyethylene glycol, 2 parts of talc, 10 parts of polyethylene wax. The antibacterial high-oxygen-barrier PE composite film was prepared as follows: the raw materials of the outer PE film, the middle PVA film, and the inner PE film were heated and melted by virtue of a twin-screw extruder. For the PE film, the heating temperatures for zones 1-7 were as follows: 160? C., 170? C., 175? C., 180? C., 185? C., 175? C., and 170? C., and the speed of the twin-screw extruder was 30 r/min. For the PVA film, the heating temperatures for zones 1-7 were as follows: 180? C., 190? C., 195? C., 195? C., 210? C., 195? C., and 180? C., and the speed of the twin-screw extruder was 30 r/min. The raw materials were extruded by virtue of a three-layer die, and the melt was cooled on a chill roller to form a cast sheet. The cast sheet was preheated in a 50? C. water bath, and then subjected to a humidity conditioning treatment in a 70? C. water bath. After the humidity conditioning, an air knife was used to blow dry the surface of the cast sheet. Finally, a conventional winding machine is used to wind up the product to obtain the antibacterial and high-oxygen-barrier PE composite film.

(67) Property Test

(68) The composite films were prepared according to the methods in the Examples and Comparative Examples, and their properties were tested with reference to the following methods. The test results were recorded in Table 2. 1. Tensile strength: The test was performed in accordance with GB/T13022-1991 Plastics-Determination of Tensile Properties of Films, where the loading speed was 1 mm/min. 2. Water vapor permeability rate: The test was performed in accordance with GB/T21529-2008 Determination of Water Vapor Permeability Rate for Plastic Film and Sheeting, where the test temperature was 40? C. and the relative humidity was 90%. 3. Oxygen permeability rate: The test was performed in accordance with GB/T19789-2005 Packaging Material-Test Method for Oxygen Gas Permeability Characteristics of Plastic Film and Sheeting-Coulometric Sensor, where the test temperature was 40? C. and the relative humidity was 90%. 4. Peel strength: The peel strength between the inner film and the outer film was tested in accordance with GB8808-1988 Test Method for T-type Peel Strength of Flexible Laminated Materials. 5. Transparency: The test was performed in accordance with GB/T2410-2008 Determination of Luminous Transmittance and Haze of Transparent Plastics.

(69) TABLE-US-00002 TABLE 2 Property test results of high-barrier polyolefin composite films vapor Tensile Water vapor Oxygen permeability Peel strength/ permeability rate cm.sup.3/ strength Trans- Index MPa rate g/(m.sup.2 .Math. 24 h) (m.sup.2 .Math. 24 h .Math. 0.1 MPa) (N/15 mm) parency/% Example 1 31.8 0.81 0.54 10.4 75 Example 2 30.4 0.88 0.60 10.1 76 Example 3 31.2 0.82 0.56 10.3 78 Example 4 31.5 0.84 0.58 10.4 77 Example 5 29.5 0.95 0.71 10.2 75 Example 6 29.1 0.84 0.67 10.3 76 Example 7 34.7 0.51 0.35 13.4 74 Example 8 34.5 0.54 0.32 13.1 75 Example 9 32.5 0.57 0.38 13.3 75 Example 10 34.6 0.68 0.47 13.4 74 Example 11 34.1 0.61 0.43 11.2 75 Example 12 35.6 0.41 0.32 15.4 73 Example 13 35.4 0.42 0.33 15.3 73 Example 14 35.6 0.46 0.33 14.7 74 Example 15 35.0 0.43 0.32 14.1 73 Example 16 32.4 0.51 0.23 15.2 75 Comparative 27.5 0.98 0.83 10.4 75 Example 1 Comparative 31.2 1.05 0.92 10.3 79 Example 2 Comparative 31.7 0.96 0.79 10.4 76 Example 3 Comparative 25.6 2.31 1.35 10.1 79 Example 4 Comparative 30.1 2.24 1.17 9.2 76 Example 5 Comparative 29.7 1.03 0.82 8.7 75 Example 6 Comparative 31.1 2.64 1.79 10.3 79 Example 7 Comparative 28.4 2.28 0.98 10.2 75 Example 8

(70) According to Table 2, the water- and oxygen-barrier masterbatches prepared in Preparation Examples 1 and 2 were used in Examples 1 and 2 respectively, and the high-barrier polyolefin composite films thus prepared have good transparency, good barrier properties against water vapor and oxygen, and also have strong adhesion between the outer PE film and the modified inner PE film.

(71) Examples 3 and 4 differ from Example 1 in the use amounts of raw materials, but the high-barrier polyolefin composite films produced in Examples 3 and 4 still have good barrier properties, transparency and mechanical properties.

(72) The water- and oxygen-barrier masterbatches prepared in Preparation Examples 3 and 4 were used in Examples 5 and 6 respectively. In Preparation Examples 3 and 4, maleic anhydride-grafted LDPE and maleic anhydride-grafted POE were used separately as compatibilizers. Compared with Example 1, Examples 5 and 6 produced the high-barrier polyolefin composite films with reduced tensile strength, weakened barrier properties and decreased adhesion between the outer PE film and the modified inner PE film, and this indicates that the combination of maleic anhydride-grafted LDPE and maleic anhydride-grafted EVA can effectively improve the compatibility of the water- and oxygen-barrier masterbatch with the raw materials of the modified inner PE film, and enhance the mechanical properties and barrier properties of the modified inner PE film.

(73) Compared with Example 1, Examples 7 and 8 used the high-barrier PVA coating solutions prepared in Preparation Examples 8 and 9 respectively, and according to Table 2, the tensile strength of the high-barrier polyolefin composite films thus prepared is increased, their barrier properties are further improved, and their adhesion between the outer PE film and the modified inner PE film is increased.

(74) Example 9 used the high-barrier coating solution prepared in Preparation Example 10 in which no chitosan was added to the high-barrier PVA coating solution, as compared with Preparation Example 8. Example 10 used the high-barrier PVA coating solution prepared in Preparation Example 11, in which no octadecyltrichlorosilane was added. According to Table 2, compared with the high-barrier polyolefin composite film prepared in Example 8, the high-barrier polyolefin composite films prepared in Examples 9 and 11 have no obvious changes in peel strength, but Example 9 shows a decrease in tensile strength and Example 10 shows weakened barrier ability.

(75) Example 11 used the high-barrier PVA coating solution prepared in Preparation Example 12, in which tannic acid was not used to treat the airgel powder, as compared with Preparation Example 8, and the high-barrier polyolefin composite film thus prepared shows a decrease in adhesion between the outer PE film and the outer PE film and its barrier properties are slightly weakened.

(76) Compared with Example 7, Examples 12 and 13 used the water-barrier adhesive prepared in Preparation Examples 13 and 14 respectively. According to Table 2, the high-barrier polyolefin composite films prepared in Examples 12 and 13 have further reduced barrier ability against water vapor and increased peel strength, indicating that the water-barrier adhesive can further improve the barrier properties and adhesion of the PE composite film.

(77) Examples 14 and 15 used the water-barrier adhesive prepared in Preparation Examples 15 and 16 respectively. Compared with Example 12, Example 14 produced the PE composite film with reduced barrier ability against water, weakened mechanical properties and decreased adhesion between the outer PE film and the modified inner PE film, and Example 15 produced the PE composite film with weakened water barrier effect.

(78) In Example 16, the outer PP film and the inner PP film were used as base materials, the water-barrier layer, the high-barrier PVA coating layer and the adhesive layer were provided between the outer PP film and the inner PP film, the water-barrier adhesive was prepared according to Preparation Example 13, and the high-barrier PVA coating solution was prepared according to Preparation Example 8. The polyolefin composite film thus prepared has a water vapor barrier property of 0.51 g/(m.sup.2.Math.24 h) and an oxygen barrier property of 0.23 cm.sup.3/(m.sup.2.Math.24 h.Math.0.1 MPa), showing a good barrier ability.

(79) Comparative Example 1 used the water- and oxygen-barrier masterbatch prepared in Preparation Example 5 in which no EVA was added. Compared with Example 1, Comparative Example 1 produced the PE composite film with weakened tensile strength and reduced barrier ability against water and oxygen.

(80) Comparative Example 2 used the water- and oxygen-barrier masterbatch prepared in Preparation Example 6 in which no single-layer graphene was added. Compared with Example 1, Comparative Example 2 produced the PE composite film with weakened barrier ability against oxygen and water.

(81) Comparative Example 3 used the water- and oxygen-barrier masterbatch prepared in Preparation Example 7, in which no polyhedral oligomeric silsesquioxane was added. Compared with Example 1, Comparative Example 3 produced the PE composite film with weakened barrier properties and the PE composite film does not show obvious changes in other properties.

(82) In Comparative Example 4, no oxygen- and water-barrier masterbatch was added. Compared with Example 1, Comparative Example 4 shows an obvious decrease in barrier ability against water vapor and oxygen and weakened tensile strength.

(83) Compared with Example 1, Comparative Example 5 does not provide a high-barrier PVA coating layer, and Comparative Example 6 does not provide a water-barrier layer. The test results in Table 2 show that the PEF composite films prepared in Comparative Examples 5 and 6 have reduced barrier ability and decreased adhesion between the outer PE film and the inner PE film.

(84) In Comparative Example 7, a commercially available PE film was used as the inner film. The barrier properties of the PE composite film prepared in Comparative Example 7 against water vapor and oxygen are significantly reduced.

(85) Comparative Example 8 produced a PE composite film prepared in the prior art. The PE composite film has high oxygen permeability and poor barrier ability against water vapor, indicating that its barrier properties need to be improved.

(86) The specific examples are merely an explanation of the present application and not intended to limit the present application. Those skilled in the art can make modifications, without creative contribution, to the examples as needed after reading this description. Any of the modifications made within the scope of the claims of the present application shall be protected by the Patent Law.