A water-based coating film and its application

Abstract

The present invention belongs to the technical field of high-functional film materials, relates to a water-based coating film in the field of food packaging, and specifically relates to a water-based coating film and its application, including water-based isocyanate, polyvinyl alcohol resin, water-based polyurethane resin and additives; the amount of the polyvinyl alcohol resin accounts for 10-70% of the total weight of the water-based coating film; the amount of the water-based isocyanate accounts for 10-50% of the weight of the polyvinyl alcohol resin; the amount of the water-based polyurethane resin accounts for 20-80% of the total weight of the water-based coating film; the amount of the additive accounts for 1-10% of the total weight of the water-based coating film; the additive is one of an antioxidant, a weathering agent, a heat stabilizer, a lubricant, a crystal nucleating agent, an ultraviolet absorber, a plasticizer, an antistatic agent, a colorant, a filler, and a surfactant, or multiple in any weight ratio. It has excellent gas barrier properties under high temperature and high humidity environments.

Description

Technical Field

[0001] The invention belongs to the technical field of high-functional film materials, relates to a water-based coating film in the field of food packaging, and specifically relates to a water-based coating film and an application thereof. Background Art

[0002] High barrier packaging materials are a type of material with excellent barrier properties that can effectively prevent the penetration of substances such as oxygen, water vapor, microorganisms and odors, thereby protecting the quality, flavor, nutrition and hygiene of the packaged contents and extending the shelf life of food, medicines, etc. This type of material is widely used in the packaging of a variety of products such as food, medicines, and chemical products. There are many types of high barrier packaging materials, the most common of which include polyvinylidene chloride (PVDC), ethylene-vinyl alcohol copolymer (EVOH), polyamide (PA), polyester (PET, PEN), etc. Each material has its own unique advantages and scope of application.

[0003] For these packaging materials, packaging materials with barrier layers are used. At present, barrier layers are accurately constructed on various substrates such as films and papers through sputtering deposition, vacuum evaporation, wet surface coating and high-efficiency printing technologies, thereby giving these substrates excellent isolation and protection functions.

[0004] In the selection of barrier layer materials, a variety of innovative solutions are presented, including metal foil and metal vapor-deposited film (such as aluminum). Toppan Printing Co., Ltd. CN200380103536.6 discloses a gas barrier layer film, in which a gas barrier vapor deposition layer containing inorganic compounds is formed on a resin substrate, and a gas barrier covering layer is formed on the gas barrier vapor deposition layer, wherein the gas barrier covering layer is formed by coating, heating and drying a coating liquid, and the coating liquid includes a silicon-containing compound and a water-soluble polymer having a hydroxyl group. Although they have excellent gas barrier properties, they are limited by opacity, low elasticity and special requirements for waste disposal.

[0005] Asahi Kasei Corporation CN98108488.5 discloses a polyvinylidene chloride resin film, which, although exhibiting excellent gas barrier properties, has caused concerns regarding environmental protection treatment due to its chlorine-containing properties.

[0006] CN200980113230.6 of Japan Synthetic Chemical Industry Co., Ltd. discloses a resin film made of non-chlorine-based water-soluble polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Although it performs well under low humidity, its gas barrier properties are significantly affected by humidity changes.

[0007] Sumitomo Chemical Co., Ltd. CN95190049.8 discloses a coating film formed by a water-soluble polymer and an inorganic layered mineral. Although this coating film has improved humidity dependence compared to a resin film formed by a water-soluble polymer, the effect is not sufficient. In addition, there is a problem of reduced adhesion to the substrate. Summary of the invention

[0008] The present application provides a water-based coating film and application thereof, which has excellent gas barrier properties under high temperature and high humidity environment.

[0009] In order to achieve the above technical purpose, the technical solution adopted in the present application is: a water-based coating film, including water-based isocyanate, polyvinyl alcohol resin, water-based polyurethane resin and additives;

[0010] The amount of the polyvinyl alcohol resin is 10-70% of the total weight of the water-based coating film;

[0011] The amount of the aqueous isocyanate is 10-50% of the weight of the polyvinyl alcohol resin;

[0012] The amount of the waterborne polyurethane resin is 20-80% of the total weight of the waterborne coating film;

[0013] The amount of the additive is 1-10% of the total weight of the water-based coating film; the additive is one or more of antioxidants, weathering agents, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, plasticizers, antistatic agents, colorants, fillers, and surfactants in any weight ratio.

[0014] As an improved technical solution of the present application, the aqueous isocyanate is a compound represented by Formula 1:

[0015] In formula I, R is an alkyl group, a carbonyl group or an aromatic group.

[0016] As an improved technical solution of the present application, the compound represented by Formula 1 is a compound obtained by reacting 3,5-dimethylpyrazole and isocyanate in a 1:1 ratio of the amount of NCO group to generate an isocyanate compound containing a pyrazole end group.

[0017] As an improved technical solution of the present application, the alcoholysis degree of the polyvinyl alcohol resin is greater than 90%, and the polymerization degree is greater than 500.

[0018] Another object of the present application is to provide an application of a water-based coating film in a high barrier packaging material.

[0019] As an improved technical solution of the present application, the thickness of the water-based coating film is 0.1-2.0 microns.

[0020] Beneficial Effects

[0021] It can be seen from the above technical scheme that the coating film of the present application includes main resins such as water-based isocyanate, polyvinyl alcohol resin, water-based polyurethane resin and additives. The water-based isocyanate of the present invention is a blocked water-based isocyanate, which is stable at room temperature, and the prepared coating liquid can extend the shelf life; on the other hand, a coating film is formed on the substrate, and under high-temperature drying, the water-based isocyanate and other resins work together to form a gas barrier film. This film not only enhances the gas barrier performance, but also ensures the excellent gas barrier performance of the material under high temperature and high humidity environments.

[0022] Compared with the existing membranes, the difference in design principle is that the present invention innovatively proposes an application scheme for water-based isocyanate, which cleverly combines it with polyvinyl alcohol resin, water-based polyurethane resin and a series of selected additives. Under room temperature conditions, this mixture exhibits excellent stability, which can effectively avoid the coagulation or precipitation that may occur in the short term, ensuring the continuous reliability of product quality. During the application of the coating process, the blocked isocyanate can be unblocked under suitable temperature conditions, undergo a cross-linking reaction with the polyvinyl alcohol resin, and synergize with other ingredients to form a coating with excellent barrier and protective properties. It is particularly worth mentioning that in the high-temperature cooking treatment stage, the coating can significantly improve the swelling problem of polyvinyl alcohol caused by high temperature, thereby greatly improving the later application adaptability and overall performance of the high-barrier film material.

[0023] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0024] The foregoing and other aspects, embodiments and features of the present invention will be more fully understood from the following description. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or will be learned from the practice of the specific embodiments according to the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme of the present application will be clearly and completely described in combination with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0026] A water-based coating film comprises water-based isocyanate, polyvinyl alcohol resin, water-based polyurethane resin and additives. The polyvinyl alcohol resin accounts for 10-70% of the total weight of the water-based coating film; the water-based isocyanate accounts for 10-50% of the weight of the polyvinyl alcohol resin; the water-based polyurethane resin accounts for 20-80% of the total weight of the water-based coating film; and the amount of the additive accounts for 1-10% of the total weight of the water-based coating film.

[0027] Wherein, the aqueous isocyanate is a compound represented by Formula 1, which generates an isocyanate compound containing a pyrazole end-capping group.

[0028]

[0029] In formula I, R is an alkyl group, a carbonyl group or an aromatic group.

[0030] The specific formula I is a nucleophilic addition reaction of 3,5-dimethylpyrazole and isocyanate in a 1:1 amount ratio of NCO group substance. The isocyanate is one or more of aromatic, aromatic aliphatic and alicyclic isocyanates in any weight ratio. Specifically, it is toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), etc.

[0031] In the water-based coating film, the water-based isocyanate accounts for 10-50% by weight of the polyvinyl alcohol resin, preferably 20-30%. The purpose is that it can be unblocked under suitable temperature conditions, undergo cross-linking reaction with the polyvinyl alcohol resin, and synergize with other ingredients to form a coating with excellent barrier and protection properties.

[0032] Wherein, the polyvinyl alcohol resin has a degree of alcoholysis greater than 90% and a degree of polymerization greater than 500. Further, the polyvinyl alcohol resin is a derivative of a polyvinyl alcohol-based polymer and a polyvinyl alcohol-based polymer. Preferably, the polyvinyl alcohol resin has a degree of alcoholysis of 95% or more and a degree of polymerization of 300 to 2500. Particularly preferred is a polyvinyl alcohol resin with a degree of alcoholysis of 95% or more and a degree of polymerization of 500 to 2000. The performance of the polyvinyl alcohol resin is significantly affected by its degree of alcoholysis and degree of polymerization. Specifically, with the increase of the degree of alcoholysis or the increase of the degree of polymerization, its hygroscopic swelling property will show a downward trend. When the degree of alcoholysis of the polyvinyl alcohol resin is lower than 95%, the polyvinyl alcohol resin will encounter challenges in constructing an effective gas barrier and it is difficult to achieve the ideal gas barrier effect. On the other hand, when the degree of polymerization is lower than 300, the resin molecular chain is relatively short, which may lead to an increase in gas permeation paths, thereby significantly reducing its gas barrier performance. On the contrary, if the degree of polymerization is too high, exceeding 2500, although it may theoretically enhance the interaction between molecules, it will also bring about a significant increase in the viscosity of the water-based coating liquid. This high viscosity state not only increases the difficulty of processing, but also may make it difficult to evenly mix the resin with other additives or components, thereby affecting the gas barrier and adhesion of the final product, resulting in performance degradation. The polyvinyl alcohol resin accounts for 10-70% of the total weight of the water-based coating film, preferably 30-50%.

[0033] The waterborne polyurethane resin is a polyurethane resin containing an acid group, and the acid group may be located at the end or side chain of the polyurethane resin, such as HP-1208 produced by Runchang Chemical and WPB-341 produced by Mitsui Chemicals of Japan.

[0034] Furthermore, the glass transition temperature of the aqueous polyurethane resin is preferably 100 to 200°C, more preferably 120 to 150°C.

[0035] Furthermore, the number average molecular weight of the aqueous polyurethane resin is preferably 1000 to 1,000,000, more preferably 1000 to 200,000, and even more preferably 1000 to 100,000.

[0036] Furthermore, the waterborne polyurethane resin is in any form of an aqueous solution that can be dissolved in an aqueous medium or an aqueous dispersion formed by dispersing the above polyurethane resin in an aqueous medium. In the aqueous dispersion, the average particle size of the waterborne polyurethane resin is preferably 20 to 600 nm, preferably 30 to 200 nm; the purpose is to provide excellent coating hardness, toughness, water resistance and wear resistance. The amount of the waterborne polyurethane resin accounts for 20-80% of the total weight of the waterborne coating film, preferably 40-60%.

[0037] The additive is one or any combination of antioxidant, weathering agent, heat stabilizer, lubricant, crystal nucleating agent, ultraviolet absorber, plasticizer, antistatic agent, colorant, filler and surfactant. The amount of the additive is 1-10% of the total weight of the water-based coating film.

[0038] The coating film is prepared into a coating liquid using a solvent system with good solubility for the above components, moderate evaporation rate and boiling point of 70-150°C, wherein the boiling point of the main solvent is preferably 100-140°C. The optional solvents include water, and at least one of methanol, ethanol, isopropanol, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, cyclohexanone, butanone, ethylene glycol monoethyl ether acetate, propylene glycol ethyl ether acetate, 2-butoxy-1-ethanol acetate, and dioxane can also be selected. The solid content of the prepared coating liquid is 4-15%. The amount of solvent used depends on the viscosity of the coating liquid required by the coating machine, and the general viscosity is 3-50mm 2 ·s -1 between.

[0039] The following are specific examples of the invention, but the content of the present invention is not limited to this. In the embodiments, toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI) are from BASF; trimethylolpropane (TMP) and dimethylolpropionic acid (DMPA) are from Beijing Bailingwei Technology Co., Ltd.; 3,5-dimethylpyrazole (DMP) is from Changzhou Wujin Kangda Chemical Co., Ltd.; propylene glycol methyl ether acetate is from Jinan Huifengda Chemical Co., Ltd.

[0040] aExample 1

[0041] Synthesis of water-based isocyanate WU1:

[0042] In a 1000ml four-necked flask with temperature control heating, mechanical stirring, condensation and reflux, add 382.8g (2.2mol) of toluene diisocyanate (TDI), 93.0g of ethyl acetate, and 82.2g of TMP, slowly heat to 70°C, react for 3h, and cool to room temperature. Take DMPA according to a certain molar ratio of OH (DMPA): NCO = 1:2-1:6, where OH (DMPA) refers to the amount of hydroxyl substances in DMPA, and NCO refers to the amount of NCO substances contained in TDI, ensuring that the molar ratio of the amount of hydroxyl substances in DMPA to the amount of NCO substances in TDI is 1:2-1:6, fully dissolve it in acetone and add it to the reaction product, heat to a certain temperature, react for several hours, cool to room temperature, and obtain a water-dispersible polyisocyanate, i.e., water-based isocyanate. Take 0.9-1.2 times the amount of free -NCO group substance as blocking agent 3,5-dimethylpyrazole (hereinafter referred to as DMP), dissolve it in a mixed solvent of appropriate amounts of ethanol and ethyl acetate, add 3,5-dimethylpyrazole (hereinafter referred to as DMP) in multiple times under stirring, and then stir at 80°C for about 3 hours, and measure the -NCO content in real time until the peak of active isocyanate group 2275 disappears as detected by infrared spectroscopy, thus obtaining water-based isocyanate WU1.

[0043] Prepare water-based coating liquid C1 according to the composition in Table 1:

[0044] Table 1 Composition and content of aqueous coating liquid C1

[0045] Ingredients content WU1 0.04 parts by weight PVA105 (KURARAY) is a polyvinyl alcohol 0.4 parts by weight WPB-341 (Mitsui Chemicals, Japan) is a water-based polyurethane resin 3.2 parts by weight S-901 (Beijing Qifei) ingredients are additives 0.36 parts by weight Deionized water 76.8 parts by weight Isopropyl alcohol 19.2 parts by weight

[0046] Preparation of high barrier film:

[0047] (1) Polymer substrate treatment: The polymer substrate is a polyethylene terephthalate film with a thickness of 12 μm (the polyethylene terephthalate film is from Shandong Fuwei), and the coated surface of the polymer substrate is subjected to corona treatment; this is a conventional treatment in the prior art;

[0048] (2) Base treatment: A polyurethane adhesive PU (acrylic polyol and toluene diisocyanate are mixed in such a way that the number of NCO groups of toluene diisocyanate is equal to the number of OH groups of acrylic polyol, and diluted with ethyl acetate so that the total solid content becomes 4% by mass) is applied on the corona-treated polymer substrate in an online or offline manner, with a coating amount of 1 g / m 2 , the drying temperature is 130℃, and the drying time is 5 minutes;

[0049] (3) Silicon oxide deposition: The substrate that has been treated with a polymer substrate and a bottom layer is placed on the surface of the upper electrode plate of a PECVD vacuum chamber for plasma enhanced chemical vapor deposition. The reaction gases are hexamethyldisiloxane and oxygen. After the reaction, silicon dioxide is generated on the surface of the substrate. The thickness of the silicon dioxide deposition layer is 20-30 nm.

[0050] (4) Top coating: Use a gravure coater to coat the aqueous coating liquid C1 at a dry coating amount of 0.2 g / m 2 The high barrier film of Example 1 was obtained by coating it on the deposition surface of the silicon dioxide coating and drying it in an oven at 120° C. for 120 seconds.

[0051] Example 2

[0052] Synthesis of waterborne isocyanate WU2:

[0053] In a 1000ml four-necked flask with temperature control heating, mechanical stirring, condensation reflux, add 488.4g of isophorone diisocyanate (IPDI), 93.0g of ethyl acetate, and 82.2g of TMP, slowly heat to 70°C, react for 3h, and cool to room temperature. Take DMPA according to a certain molar ratio of OH (DMPA): NCO = 1:2-1:6, fully dissolve it in acetone and add it to the reaction product, heat to a certain temperature, react for several hours, cool to room temperature, and prepare a water-dispersible polyisocyanate. Take 0.9-1.2 times the amount of free -NCO group substance as blocking agent 3,5-dimethylpyrazole (hereinafter referred to as DMP), dissolve it in a mixed solvent of appropriate amounts of ethanol and ethyl acetate, add 3,5-dimethylpyrazole (hereinafter referred to as DMP) in multiple times under stirring, and then stir at 80°C for about 3 hours, and measure the -NCO content in real time until the peak of active isocyanate group 2275 disappears as detected by infrared spectroscopy, thus obtaining water-based isocyanate WU2.

[0054] Prepare aqueous coating liquid C2 according to the composition in Table 2:

[0055] Table 2 Composition and content of aqueous coating liquid C2

[0056] Ingredients content WU2 1.35 parts by weight PVA110 (KURARAY) is a polyvinyl alcohol 10.5 parts by weight HP-1208 (Runchang Chemical) is a water-based polyurethane resin 3.0 parts by weight WA100 (Shanghai Motian) ingredients are additives 0.15 parts by weight Deionized water 68.0 parts by weight Isopropyl alcohol 17.0 parts by weight

[0057] Preparation of high barrier film:

[0058] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the aqueous coating liquid C2 using a gravure coater at a dry coating amount of 3 g / m 2 The coating was applied on the plated surface in the manner of , and dried in an oven at 120° C. for 120 seconds to obtain the high barrier film of Example 2.

[0059] Example 3

[0060] Synthesis of water-based isocyanate WU3:

[0061] In a 1000ml four-necked flask with temperature control heating, mechanical stirring, condensation reflux, add 550.6g of diphenylmethane diisocyanate (MDI), 93.0g of ethyl acetate, and 82.2g of TMP, slowly heat to 70°C, react for 3h, and cool to room temperature. Take DMPA according to a certain molar ratio of OH (DMPA): NCO = 1:2-1:6, fully dissolve it in acetone and add it to the reaction product, heat to a certain temperature, react for several hours, cool to room temperature, and prepare a water-dispersible polyisocyanate. Take 0.9-1.2 times the amount of free -NCO group substance as blocking agent 3,5-dimethylpyrazole (hereinafter referred to as DMP), dissolve it in a mixed solvent of appropriate amounts of ethanol and ethyl acetate, add 3,5-dimethylpyrazole (hereinafter referred to as DMP) in multiple times under stirring, and then stir at 80°C for about 3 hours, and measure the -NCO content in real time until the peak of active isocyanate group 2275 disappears as detected by infrared spectroscopy, thus obtaining water-based isocyanate WU3.

[0062] Prepare water-based coating liquid C3 according to the composition in Table 3:

[0063] Table 3 Composition and content of aqueous coating liquid C3

[0064] Ingredients content WU3 0.40 parts by weight PVA105 (KURARAY) is a polyvinyl alcohol 3.0 parts by weight WPB-341 (Mitsui Chemicals, Japan) is a water-based polyurethane resin 6.0 parts by weight S-901 (Beijing Qifei) ingredients are additives 0.60 parts by weight Deionized water 72.0 parts by weight Isopropyl alcohol 18.0 parts by weight

[0065] Preparation of high barrier film:

[0066] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the aqueous coating liquid C3 using a gravure coater at a dry coating amount of 0.2 g / m 2 The coating was applied on the plated surface in the manner of the present invention, and dried in an oven at 120° C. for 120 seconds to obtain the high barrier film of Example 3.

[0067] Example 4

[0068] Synthesis of water-based isocyanate WU4:

[0069] In a 1000ml four-necked flask with temperature control heating, mechanical stirring, condensation reflux, add 577.2g of dicyclohexylmethane diisocyanate (HMDI), 93.0g of ethyl acetate, and 82.2g of TMP, slowly heat to 70°C, react for 3h, and cool to room temperature. Take DMPA according to a certain molar ratio of OH (DMPA): NCO = 1:2-1:6, fully dissolve it in acetone and add it to the reaction product, heat to a certain temperature, react for several hours, cool to room temperature, and prepare a water-dispersible polyisocyanate. Take 0.9-1.2 times the amount of free -NCO group substance as blocking agent 3,5-dimethylpyrazole (hereinafter referred to as DMP), dissolve it in a mixed solvent of appropriate amounts of ethanol and ethyl acetate, add 3,5-dimethylpyrazole (hereinafter referred to as DMP) in multiple times under stirring, and then stir at 80°C for about 3 hours, and measure the -NCO content in real time until the peak of active isocyanate group 2275 disappears as detected by infrared spectroscopy, thus obtaining water-based isocyanate WU4.

[0070] Prepare aqueous coating liquid C4 according to the composition in Table 4:

[0071] Table 4 Composition and content of aqueous coating liquid C3

[0072] Ingredients content WU4 0.64 parts by weight PVA117 (KURARAY) Polyvinyl alcohol 4.0 parts by weight HP-1208 (Runchang Chemical) waterborne polyurethane resin 2.56 parts by weight S-901 (Beijing Qifei) Additive 0.80 parts by weight Deionized water 73.6 parts by weight Isopropyl alcohol 18.4 parts by weight

[0073] Preparation of high barrier film:

[0074] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the aqueous coating liquid C4 using a gravure coater at a dry coating amount of 0.8 g / m 2 The coating was applied on the plated surface in the manner of the present invention, and dried in an oven at 120° C. for 120 seconds to obtain the high barrier film of Example 4.

[0075] Example 5

[0076] Synthesis of water-based isocyanate WU5:

[0077] In a 1000ml four-necked flask with temperature control heating, mechanical stirring, condensation reflux, add 370.0g of hexamethylene diisocyanate (HDI), 93.0g of ethyl acetate, and 82.2g of TMP, slowly heat to 70°C, react for 3h, and cool to room temperature. Take DMPA according to a certain molar ratio of OH (DMPA): NCO = 1:2-1:6, fully dissolve it in acetone and add it to the reaction product, heat to a certain temperature, react for several hours, cool to room temperature, and prepare a water-dispersible polyisocyanate. Take 0.9-1.2 times the amount of free -NCO group substance as blocking agent 3,5-dimethylpyrazole (hereinafter referred to as DMP), dissolve it in a mixed solvent of appropriate amounts of ethanol and ethyl acetate, add 3,5-dimethylpyrazole (hereinafter referred to as DMP) in multiple times under stirring, and then stir at 80°C for about 3 hours, and measure the -NCO content in real time until the peak of active isocyanate group 2275 disappears as detected by infrared spectroscopy, thus obtaining water-based isocyanate WU5.

[0078] Prepare water-based coating liquid C5 according to the composition in Table 5:

[0079] Table 5 Composition and content of aqueous coating liquid C5

[0080] Ingredients content WU5 0.91 parts by weight PVA117 (KURARAY) Polyvinyl alcohol 2.80 parts by weight WPB-341 (Japan Mitsui Chemicals) waterborne polyurethane resin 2.80 parts by weight 104E (Ruikaibang) additive 0.49 parts by weight Deionized water 74.4 parts by weight Isopropyl alcohol 18.6 parts by weight

[0081] Preparation of high barrier film:

[0082] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the water-based coating liquid C5 using a gravure coater at a dry coating amount of 1.2 g / m 2 The coating was applied on the plated surface in the manner of the present invention, and dried in an oven at 120° C. for 120 seconds to obtain the high barrier film of Example 5.

[0083] Example 6

[0084] Synthesis of water-based isocyanate WU6:

[0085] In a 1000ml four-necked flask with temperature control heating, mechanical stirring, condensation reflux, add 497.7g of lysine diisocyanate (LDI), 93.0g of ethyl acetate, and 82.2g of TMP, slowly heat to 70°C, react for 3h, and cool to room temperature. Take DMPA according to a certain molar ratio of OH (DMPA): NCO = 1:2-1:6, fully dissolve it in acetone and add it to the reaction product, heat to a certain temperature, react for several hours, cool to room temperature, and prepare a water-dispersible polyisocyanate. Take 0.9-1.2 times the amount of free -NCO group substance as blocking agent 3,5-dimethylpyrazole (hereinafter referred to as DMP), dissolve it in a mixed solvent of appropriate amounts of ethanol and ethyl acetate, add 3,5-dimethylpyrazole (hereinafter referred to as DMP) in multiple times under stirring, and then stir at 80°C for about 3 hours, and measure the -NCO content in real time until the peak of active isocyanate group 2275 disappears as detected by infrared spectroscopy, thus obtaining water-based isocyanate WU6.

[0086] Prepare water-based coating liquid C6 according to the composition in Table 6:

[0087] Table 6 Composition and content of aqueous coating liquid C6

[0088]

[0089]

[0090] Preparation of high barrier film:

[0091] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the water-based coating liquid C6 using a gravure coater at a dry coating amount of 0.7 g / m 2 The high barrier film of Example 6 was obtained by coating it on the plated surface and drying it in an oven at 120° C. for 120 seconds.

[0092] Comparative Example 1

[0093] Prepare water-based coating liquid C7 according to the composition in Table 7:

[0094] Table 7 Composition and content of aqueous coating liquid C7

[0095] Ingredients content PVA117 (KURARAY) Polyvinyl alcohol 3.4 parts by weight WPB-341 (Japan Mitsui Chemicals) waterborne polyurethane resin 6.0 parts by weight S-901 (Beijing Qifei) Additive 0.60 parts by weight Deionized water 72.0 parts by weight Isopropyl alcohol 18.0 parts by weight

[0096] Preparation of high barrier film:

[0097] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the aqueous coating liquid C7 using a gravure coater at a dry coating amount of 1 g / m 2 The coating was applied on the plated surface in a manner and dried in an oven at 120° C. for 120 seconds to obtain a high barrier film of Comparative Example 1.

[0098] Comparative Example 2

[0099] Prepare water-based coating liquid C8 according to the composition in Table 8:

[0100] Table 8 Composition and content of aqueous coating liquid C8

[0101]

[0102]

[0103] Preparation of high barrier film:

[0104] According to the preparation process of the high barrier film in Example 1, the top layer is coated with the water-based coating liquid C8 using a gravure coater at a dry coating amount of 1 g / m 2 The coating was applied on the plated surface in a manner and dried in an oven at 120° C. for 120 seconds to obtain a high barrier film of Comparative Example 2.

[0105] The performance of the high barrier films in the above embodiments and comparative examples was evaluated according to the following test methods:

[0106] First, high barrier packaging material preparation:

[0107] The high barrier packaging materials of the embodiments and comparative examples were obtained by dry-compounding PA and RCPP on the top layer of the high barrier films of the embodiments and comparative examples using polyurethane glue PP3111 / I3000 and then aging at 50 degrees for 3 days.

[0108] 1. Determination of film coating thickness:

[0109] The high barrier film was tested using an optical film thickness meter (F20-UV manufactured by Filmetrics, USA) in accordance with the national standard GB / T33051-2016 “Measurement method for thickness of hardened layer of optical functional film surface hardened film”.

[0110] 2. Film transmittance determination:

[0111] The high barrier film was tested using a haze meter (M57D manufactured by DIFFUSION, UK) in accordance with the national standard GB / T 2410-2008 “Determination of light transmittance and haze of transparent plastics”.

[0112] 3. Film oxygen transmission rate (OTR) determination:

[0113] The high barrier film is tested using Guangzhou Marking Y210 oxygen permeability tester in accordance with the national standard GB / T19789-2005 "Oxidation permeability test method for plastic films and sheets for packaging materials - Coulometric test method".

[0114] 4. Determination of film water vapor transmission rate (WVTR):

[0115] For the moisture resistance evaluation of high barrier films, the water vapor transmission rate is measured according to the national standard GB / T21529-2008 "Electrolytic sensor method for the determination of water vapor transmission rate of plastic films and sheets" at a temperature of 40°C and a relative humidity of 90%. The measurement equipment uses a water vapor transmission tester manufactured by MOCON, USA, and the measurement is carried out under the condition that the relative humidity on the water vapor supply side is 90% RH. The measured value is expressed in g / m 2 ·day indicates.

[0116] 5. Film peel strength determination:

[0117] A 15 mm wide sample was cut from the high barrier packaging material, and the peel strength between the substrates was measured using a tensile tester (manufactured by Sansi Zongheng Co., Ltd., model UTM2203) at a tensile speed of 300 mm / min and a tensile angle of 180 degrees. In addition, the peel strength was considered to be acceptable if it was 2.0 N / 15 mm or more.

[0118] 6. High temperature cooking resistance:

[0119] Heat-seal bags of high-barrier packaging materials with a size of 20 cm*30 cm, fill the contents with water, and steam-cook the bags at 121°C for 30 minutes in an autoclave. Visually check the appearance of the packaging container after steaming and sterilization to see if delamination occurs. The evaluation is divided into the following two levels: "○ (good)" if no delamination occurs; "× (bad)" if delamination occurs.

[0120] 7. Printing adaptability:

[0121] The high-barrier film was printed using a Zhuxin ZXYT-41000 four-color flexographic printing press, and the X.rite Pantone eXact scanning spectrophotometer was used to rate the print quality on a 5-point scale, 1-5, with 5 being the best and 1 being the worst, according to the PantoneLIVE color digital workflow.

[0122] The performance of the high barrier film examples and comparative examples are shown in Table 9.

[0123] Table 9 Performance of high barrier films of Examples 1-6 and Comparative Examples 1-2

[0124]

[0125] From the above results, it can be seen that the high barrier film of the present invention has the advantages of good transparency, high barrier properties, high temperature cooking resistance, high peel strength and good printing adaptability. It can be used to manufacture oxygen barrier and water vapor barrier packaging materials, and can be applied in packaging fields such as food packaging, pharmaceutical packaging, and electronic products.

[0126] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A water-based coating film, characterized in that: Including water-based isocyanate, polyvinyl alcohol resin, water-based polyurethane resin and additives; The amount of the polyvinyl alcohol resin is 10-70% of the total weight of the water-based coating film; The amount of the aqueous isocyanate is 10-50% of the weight of the polyvinyl alcohol resin; The amount of the waterborne polyurethane resin is 20-80% of the total weight of the waterborne coating film; The additive is used in an amount of 1-10% of the total weight of the water-based coating film; The additive is one or more of antioxidants, weathering agents, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, plasticizers, antistatic agents, colorants, fillers, and surfactants in any weight ratio.

2. A water-based coating film according to claim 1, characterized in that: The aqueous isocyanate is a compound represented by Formula 1: In formula I, R is an alkyl group, a carbonyl group or an aromatic group.

3. A water-based coating film according to claim 2, characterized in that: The compound represented by formula 1 is prepared by a nucleophilic addition reaction of 3,5-dimethylpyrazole and isocyanate in a 1:1 ratio of the amount of NCO group to generate an isocyanate compound containing a pyrazole end-capping group.

4. A water-based coating film according to claim 3, characterized in that: The isocyanate is one or more selected from aromatic, aromatic aliphatic and alicyclic isocyanates in any weight ratio.

5. The water-based coating film according to claim 1, characterized in that: The alcoholysis degree of the polyvinyl alcohol resin is greater than 90%, and the polymerization degree is greater than 500.

6. The water-based coating film according to claim 1, characterized in that: The glass transition temperature of the aqueous polyurethane resin is preferably 100 to 200°C.

7. Use of the aqueous coating film as claimed in any one of claims 1 to 6 in high barrier packaging materials.

8. The use of a water-based coating film in a high barrier packaging material according to claim 7, characterized in that: The water-based coating film thickness is 0.1-2.0 microns.

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