Polyurethane coating liquid as well as preparation method and application thereof

Abstract

The invention relates to the field of barrier materials, in particular to polyurethane coating liquid as well as a preparation method and application thereof. The invention provides polyurethane coating liquid. The polyurethane coating liquid is prepared from the following components in parts by weight: 100 parts of polyester polyol, 0.3 to 30.0 parts of isocyanate, 4.5 to 15.0 parts of thermoplastic polyurethane resin, 0.01 to 3.70 parts of a dynamic cross-linking agent, 0.06 to 14.50 parts of an adhesion promoter, 0.06 to 7.10 parts of a latent curing agent, 0 to 20.00 parts of an auxiliary agent and 40 to 850 parts of a solvent. The polyurethane coating liquid provided by the invention can be used as a base material and a bottom coating layer of a high-barrier functional layer, the firmness between the base material and the high-barrier functional layer is effectively improved by adjusting the proportion of soft and hard sections of polyurethane and introducing a dynamic cross-linking agent and a latent curing agent, and the high-barrier functional layer can be used as a high-barrier coating layer. Meanwhile, it is guaranteed that the prepared high-barrier material has excellent steaming and boiling resistance, high-temperature and high-humidity resistance, rubbing resistance and bending resistance.

Description

Technical Field

[0001] The invention relates to the field of barrier materials, and in particular to a polyurethane coating liquid and a preparation method and application thereof. Background Art

[0002] In recent years, people have been actively developing packaging materials with excellent gas barrier properties and water vapor barrier properties. The high barrier materials widely used in the market currently include oxide deposition barrier films, coated high barrier films, metal foils, metallized films, ethylene-vinyl alcohol copolymer (EVOH) multilayer co-extruded films and other materials. Among them, oxide deposition barrier films, coated high barrier films and metallized films are the most widely used in the field of high barrier packaging.

[0003] The three types of films, oxide deposition barrier film, coated high barrier film, and metallized film, all require a flexible substrate as the substrate, and the barrier layer is deposited by dry or wet film forming technology, so the fastness between the barrier layer and the substrate is the key to evaluating the performance of this series of barrier film materials. The main problem with the above materials in practical applications is that under the conditions of cooking, high temperature and humidity, bending and rubbing, the fastness between the barrier layer and the substrate is prone to deterioration, resulting in a decrease in barrier performance.

[0004] In summary, how to improve the fastness between the substrate and the barrier functional layer is an urgent problem to be solved in the field of high barrier packaging films. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a polyurethane coating liquid and a preparation method and use thereof. The polyurethane coating liquid provided by the present invention can be used as a base coat of a substrate and a high barrier functional layer, and by adjusting the ratio of the soft and hard segments of the polyurethane and introducing a dynamic crosslinking agent and a latent curing agent, the fastness between the substrate and the high barrier functional layer is effectively improved, and at the same time, the prepared high barrier material is ensured to have excellent boiling resistance, high temperature and high humidity resistance, rubbing resistance, and bending resistance.

[0006] The invention provides a polyurethane coating liquid, which is prepared from the following components in parts by weight: 100 parts of polyester polyol, 0.3-30.0 parts of isocyanate, 4.5-15.0 parts of thermoplastic polyurethane resin, 0.01-3.70 parts of dynamic crosslinking agent, 0.06-14.50 parts of adhesion promoter, 0.06-7.10 parts of latent curing agent, 0-20.00 parts of auxiliary agent, and 40-850 parts of solvent.

[0007] Optionally, the polyester polyol includes at least one of aliphatic polyester polyol, aromatic polyester polyol and mixed acid polyester polyol; the number average molecular weight of the polyester polyol is 300 to 150,000, and the hydroxyl value is 0.1 mg KOH / g to 250 mg KOH / g;

[0008] The isocyanate includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, dicyclohexylmethane diisocyanate trimer and methylcyclohexyl diisocyanate trimer.

[0009] Optionally, the thermoplastic polyurethane resin includes at least one of polycarbonate polyurethane resin, polyolefin polyurethane resin, polyether polyurethane resin and polyester polyurethane resin, wherein the number average molecular weight of the thermoplastic polyurethane resin is 5,000 to 100,000.

[0010] Optionally, the dynamic crosslinking agent includes at least one of 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-isopropylimidazole and 1,5,7-triazabicyclo[4.4.0]dec-5-ene;

[0011] The latent curing agent includes at least one of an imine latent curing agent and an oxazolidine latent curing agent.

[0012] Optionally, the adhesion promoter includes at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent and a zirconate coupling agent.

[0013] Optionally, the auxiliary agent includes at least one of an antioxidant, an anti-ultraviolet agent and a leveling agent.

[0014] The present invention also provides a method for preparing the polyurethane coating liquid described in the above technical solution, comprising the following steps:

[0015] (1) mixing polyester polyol, isocyanate and solvent, and performing prepolymerization reaction to obtain a polyurethane prepolymer solution,

[0016] (2) dissolving a thermoplastic polyurethane resin in a solvent to obtain a thermoplastic polyurethane resin solution,

[0017] (3) mixing the thermoplastic polyurethane solution, a dynamic crosslinking agent, an adhesion promoter, a latent curing agent, an auxiliary agent and the polyurethane prepolymer solution to obtain the polyurethane coating solution,

[0018] There is no limitation on the order of step (1) and step (2).

[0019] The present invention also provides use of the polyurethane coating liquid described in the above technical solution or the polyurethane coating liquid obtained by the preparation method described in the above technical solution in the preparation of barrier materials.

[0020] Optionally, the barrier material is prepared from the polyurethane coating liquid.

[0021] Optionally, the barrier material includes a primer layer and a barrier functional layer, wherein the primer layer is in contact with the substrate, and the primer layer is prepared from the polyurethane coating liquid.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] 1. The polyurethane coating liquid provided by the present invention effectively improves the fastness between the high barrier functional layer and the substrate by adjusting the soft and hard segments of the polyurethane material and introducing a dynamic cross-linking agent into the base coat, thereby enhancing the rubbing and bending resistance of the high barrier material.

[0024] 2. The polyurethane coating liquid provided by the present invention significantly improves the barrier properties of the high barrier film prepared using the polyurethane coating liquid as the base coating through the synergistic effect of the dynamic crosslinking agent and the latent curing agent. At the same time, the prepared barrier film has excellent boiling resistance.

[0025] 3. The preparation process of the polyurethane coating liquid prepared by the present invention is simplified, and the formed coating can be applied to plastic films, paper bases, wooden boards, metal boards, fiber fabrics, textiles, composites composed of various materials, and rubber materials, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the present invention will be apparent from the following description of preferred embodiments and accompanying drawings which illustrate the subject matter of the present invention and its use, in which:

[0027] Figure 1 It is a schematic structural diagram of a barrier film of the present invention.

[0028] Figure 2 The invention discloses a fiber fabric-based gas-barrier flexible material.

[0029] The reference numerals in the figures are respectively: 1-substrate; 2-primer coating; 3-barrier layer; 4-barrier layer; 5-primer coating; 6-fabric; 7-primer coating; 8-barrier layer. DETAILED DESCRIPTION

[0030] The present invention will be described below by specific examples, and it will be appreciated by those skilled in the art that the following specific examples are only for illustrative purposes, and do not limit the scope of the present invention in any way. In addition, in the following examples, unless otherwise specified, the reagents and equipment used are all commercially available. If in the following examples, specific treatment conditions and treatment methods are not clearly described, then conditions and methods known in the art can be used to process.

[0031] The invention provides a polyurethane coating liquid, which is prepared from the following components in parts by weight: 100 parts of polyester polyol, 0.3-30.0 parts of isocyanate, 4.5-15.0 parts of thermoplastic polyurethane resin, 0.01-3.70 parts of dynamic crosslinking agent, 0.06-14.50 parts of adhesion promoter, 0.06-7.10 parts of latent curing agent, 0-20.00 parts of auxiliary agent, and 40-850 parts of solvent.

[0032] In the present invention, a specific weight portion of polyester polyol and isocyanate first form a polyurethane prepolymer with a suitable ratio of soft and hard segments, and work together with a dynamic crosslinker and a latent curing agent at a specific ratio to effectively improve the fastness between the high barrier functional layer and the substrate, while ensuring that the prepared high barrier material has excellent resistance to boiling, high temperature and humidity, rubbing and bending. Therefore, the polyurethane coating liquid of the present invention can also be expressed as a weight portion, including the following components: 100.3-130.0 parts of polyurethane prepolymer, 4.5-15 parts of thermoplastic polyurethane resin, 0.01-3.70 parts of dynamic crosslinking agent, 0.06-14.5 parts of adhesion promoter, 0.06-7.1 parts of latent curing agent, 0-20 parts of auxiliary agent, 40-850 parts of solvent, the polyurethane prepolymer is obtained by prepolymerizing polyester polyol and isocyanate in a mass ratio of 100: (0.3-30).

[0033] Polyester polyols are produced by the condensation of polyacids and polyols. The characteristics of their structure are that the concentration of branch points is relatively high, and the distance from the branch points to the reaction points is relatively long, and the steric hindrance of the activity of the side chain functional groups is relatively small, so that the polyester polyols show higher activity. At the same time, the prepared coating has high temperature resistance and flexibility, so that the prepared polyurethane has better adhesion to relatively hard barrier layers such as metal deposition layers and inorganic oxide deposition layers, which can effectively prevent relatively hard barrier layers such as metal deposition layers and inorganic oxide deposition layers from cracking or peeling during use.

[0034] In some embodiments of the present invention, the polyester polyol includes at least one of aliphatic polyester polyol, aromatic polyester polyol and mixed acid polyester polyol, specifically polyadipate polyester polyol, polycaprolactone polyol, phthalic anhydride polyester polyol, terephthalic acid polyester polyol, isophthalic acid polyester polyol, alkyd polyester polyol, acrylic polyester polyol, mixed dibasic acid polyester polyol; the number average molecular weight of the polyester polyol is 300-150000, specifically 300, 400, 500, 600, 700, 50000, 65000, 100000, 130000, 150000, and any number average molecular weight between the above specific number average molecular weights; the hydroxyl value of the polyester polyol is 0.1mg KOH / g-250mg KOH / g, specifically 0.1mg KOH / g, 1mg KOH / g, 5mg KOH / g, 10 mg KOH / g, 20 mg KOH / g, 50 mg KOH / g, 100 mg KOH / g, 110 mg KOH / g, 150 mg KOH / g, 210 mg KOH / g, 250 mg KOH / g, and any number average molecular weight between the above specific hydroxyl values.

[0035] In the present invention, based on the weight of polyester polyol, the components for preparing the polyurethane coating solution include: 0.3 to 30.0 parts of isocyanate, specifically 0.3, 3.0, 4.0, 10.0, 20.0 and 30.0 parts, or any value in between.

[0036] In some embodiments of the present invention, the isocyanate includes toluene diisocyanate, diphenylmethane diisocyanate, polymerized diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, lysine diisocyanate, trimethyl hexamethylene diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, dicyclohexylmethane diisocyanate trimer and methylcyclohexyl diisocyanate trimer. At least one of the trimer. When the isocyanate includes more than two isocyanates, the present invention does not specifically limit the ratio of the multiple isocyanates. In an embodiment of the present invention, the isocyanate is a mixture of diphenylmethane diisocyanate and isophorone diisocyanate in a mass ratio of 1:5.7.

[0037] The hydroxyl group in the polyester polyol of the present invention reacts with the isocyanate group in the isocyanate to produce the polyurethane prepolymer, in order to effectively control the matching type of the soft and hard ends of the polyurethane prepolymer, so as to improve the flexibility and temperature resistance of the prepared polyurethane coating. If the amount of polyester polyol added is too low, the flexibility of the prepared primer coating will be deteriorated, thereby affecting the cooking resistance and rubbing resistance of the prepared high barrier film.

[0038] In the present invention, based on the weight of polyester polyol, the components for preparing the polyurethane coating solution include: 4.5 to 15.0 parts of thermoplastic polyurethane resin, specifically 4.5, 7.0, 11.3, 15.0 parts, or any value in between.

[0039] The molecules of thermoplastic polyurethane resin are basically in a linear state, with almost no chemical crosslinking points and physical crosslinking. It mainly plays two roles in the formulation of the present invention. On the one hand, it synergizes with the polyurethane prepolymer and utilizes the flexibility of its linear molecular chain to effectively improve the flexibility of the base coating, especially the rubbing and bending resistance of the high barrier material; on the other hand, as a dispersant of the polyurethane base coating liquid in the present invention, it effectively ensures the dispersibility of the dynamic crosslinking agent, adhesion promoter, and latent curing agent in the polyurethane base coating liquid. In the embodiments of the present invention, the specific type of the thermoplastic polyurethane resin is not particularly limited, and those skilled in the art can select it according to actual conditions. In some embodiments of the present invention, the thermoplastic polyurethane resin includes at least one of a polycarbonate polyurethane resin, a polyolefin polyurethane resin, a polyether polyurethane resin, and a polyester polyurethane resin, wherein the number average molecular weight of the thermoplastic polyurethane resin is 5000 to 100000, and specifically can be 50000, 70000, and 100000. The inventors found that if the number average molecular weight is too low, the flexibility of the base coating will deteriorate, affecting the rubbing and bending resistance of the high barrier material; if the number average molecular weight is too high, the solubility of the polyurethane material will deteriorate, which is not conducive to its role as a disperser in the formulation.

[0040] In the present invention, based on the weight of polyester polyol, the components for preparing the polyurethane coating solution include: 0.01 to 3.70 parts of dynamic crosslinking agent, specifically 1.0, 3.08, 3.70 parts, or any value in between.

[0041] The dynamic crosslinking agent described in the present invention is a chemical substance that can realize the dynamic crosslinking process of polymer materials. Its core lies in the formation and breaking of dynamic covalent bonds, so that the polymer network can reversibly change its structural state under specific conditions (such as temperature changes). In some embodiments of the present invention, a crosslinking agent containing a nitrogen heterocyclic conjugated structure is selected as a dynamic crosslinking agent, which can further crosslink with the hydroxyl group in the polyester polyol in a high temperature and high humidity environment, so that the coating exhibits higher heat resistance. In some embodiments of the present invention, the dynamic crosslinking agent includes at least one of 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-isopropylimidazole and 1,5,7-triazabicyclo[4.4.0]dec-5-ene. In the present invention, if the amount of dynamic crosslinking agent added is too small, the effect of dynamic crosslinking cannot be achieved, and if the amount added is too large, the stability of the coating solution will deteriorate, which is also uneconomical.

[0042] In the present invention, based on the weight of polyester polyol, the components for preparing the polyurethane coating solution include: 0.06 to 14.50 parts of adhesion promoter, specifically 0.50, 3.33, 8.33, 10, 14.50 parts, or any value in between.

[0043] In some embodiments of the present invention, the adhesion promoter includes at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and a zirconate coupling agent. In some embodiments of the present invention, the adhesion promoter is a multifunctional compound with silicon, aluminum, titanium, and zirconium as the central element. On the one hand, the adhesion promoter can react with active groups such as hydroxyl and amino groups in the polyurethane coating liquid, and at the same time, it can promote chemical adsorption between the primer layer and the substrate and the functional layer, thereby improving the adhesion between the layers. In an embodiment of the present invention, the adhesion promoter specifically includes at least one of tetramethoxysilane, tetraethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, diethylaminomethyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, triethyl borate and nitrilotri(methylenephosphonic acid), triethoxyaluminum, triisopropoxyaluminum, tri-n-butylaluminum, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-butyltitanium, tetraethoxyzirconium and tetraisopropoxyzirconium.

[0044] In the present invention, the components for preparing the polyurethane coating liquid include, by weight: 0.06 to 7.10 parts of latent curing agent, specifically 0.2, 0.72, 2.00, 4.05, 7.10 parts, or any value in between.

[0045] Latent curing agent mainly refers to the latent curing agent used in the polyurethane system. This series of curing agents can coexist with the main resin for a long time, but when subjected to external factors such as heating, light, moisture, pressure, etc., the curing agent will be activated and cross-linked with the main resin, thereby further improving the physical and chemical properties of the main resin. The present invention mainly utilizes the characteristics of the latent curing agent to further improve the flexibility of the primer coating under external factors such as high temperature, high humidity, and pressure, thereby ensuring the stability of the barrier properties of the high barrier material.

[0046] In some embodiments of the present invention, the latent curing agent includes at least one of an imine latent curing agent and an oxazolidine latent curing agent.

[0047] The latent curing agent described in the present invention includes at least one of an imine latent curing agent and an oxazolidine latent curing agent, specifically including at least one of an oxazolidine latent curing agent ALT-101, an oxazolidine latent curing agent ALT-401, an imine latent curing agent YRLH-1106, an oxazolidine latent curing agent TP-820, an oxazolidine latent curing agent PZ-005, an imine latent curing agent Alt-102, an imine latent curing agent Alt-105, an oxazolidine latent curing agent TKTY-001, and an aromatic imine latent curing agent XYlink-401.

[0048] In the present invention, the latent curing agent and the dynamic cross-linking agent can synergistically improve the high temperature, high humidity and rubbing resistance of the base coating, especially improve the boiling resistance of the high barrier material. In the present invention, if the amount of latent curing agent added is too small, the curing effect is not obvious, and if the amount of latent curing agent added is too large, the stability of the coating liquid is affected and it is not economical.

[0049] In the present invention, based on the weight of polyester polyol, the components for preparing the polyurethane coating solution include: 0 to 20.00 parts of auxiliary agent, specifically 0.60, 3.60, 16.0, and 20.00 parts, or any value in between.

[0050] Those skilled in the art may selectively add additives as needed. In some embodiments of the present invention, the additives include at least one of an antioxidant, an ultraviolet absorber and a leveling agent. The above-mentioned additives are all commonly used additives by technicians in the field, and those skilled in the art can select them as needed. In some embodiments of the present invention, the antioxidant includes at least one of antioxidant 1010, antioxidant 168, antioxidant 1076 and antioxidant 1726; the ultraviolet absorber includes at least one of UV477, UV384-2, UV1130 and UV400; the leveling agent includes at least one of a silicone leveling agent, an acrylate leveling agent and a fluorocarbon leveling agent.

[0051] In the present invention, based on the weight of polyester polyol, the components for preparing the polyurethane coating solution include: 40 to 850 parts of solvent, specifically 90.5, 186.1, 200, 205, 653.5 parts, or any value in between.

[0052] In some embodiments of the present invention, the solvent is a mixture of butanone and ethyl acetate; the present invention has no special requirements on the mass ratio of butanone and ethyl acetate, and the thermoplastic polyurethane resin can be stably dissolved as the standard. In some embodiments of the present invention, the mass ratio of butanone and ethyl acetate is 0.2 to 10:1. If the amount of ethyl acetate added is too high, the solubility of the thermoplastic polyurethane resin will deteriorate, and if the amount of butanone added is too high, it will be uneconomical, so the solvent with the above ratio is used.

[0053] The solid content of the polyurethane coating liquid prepared by the raw materials in the above ratio is 20% to 70%, preferably 30% to 50%. If the solid content of the coating liquid is too high, the viscosity of the coating liquid will be too high, affecting the uniformity of the preparation of the base coating layer. If the solid content is too low, the viscosity of the coating liquid will be too thin and the density and uniformity of the base coating layer cannot be guaranteed. The solid content of the polyurethane coating liquid prepared by the raw materials in the above ratio is moderate, which can fully guarantee the density and uniformity of the coating. The present invention also provides a method for preparing the polyurethane coating liquid described in the above technical solution, comprising the following steps:

[0054] (1) mixing polyester polyol, isocyanate and solvent, and performing prepolymerization reaction to obtain a polyurethane prepolymer solution,

[0055] (2) dissolving a thermoplastic polyurethane resin in a solvent to obtain a thermoplastic polyurethane resin solution,

[0056] (3) mixing the thermoplastic polyurethane solution, a dynamic crosslinking agent, an adhesion promoter, a latent curing agent, an auxiliary agent and the polyurethane prepolymer solution to obtain the polyurethane coating solution,

[0057] There is no limitation on the order of step (1) and step (2).

[0058] The invention firstly mixes polyester polyol, isocyanate and solvent, and performs prepolymerization reaction to obtain a polyurethane prepolymer solution.

[0059] In some embodiments of the present invention, the solvent in step (1) is preferably ethyl acetate; in step (1), based on 100 parts by weight of the polyester polyol, the amount of ethyl acetate added is 40 to 130 parts by weight.

[0060] In some embodiments of the present invention, the temperature of the prepolymerization reaction is 45-100°C, specifically 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 80°C, 90°C and 100°C, and any temperature between the above values; the time of the prepolymerization reaction is 0.5-1.5h, specifically 0.5h, 1h and 1.5h, and any time between the above values; the prepolymerization reaction is carried out under stirring conditions, the stirring speed is 10r / min-500r / min, and the time is 0.5-1.5h. The present invention dissolves the thermoplastic polyurethane resin in a solvent to obtain a thermoplastic polyurethane resin solution.

[0061] In some embodiments of the present invention, the solvent in step (2) is a mixed solution of butanone and ethyl acetate, and the weight ratio of butanone to ethyl acetate is 1:1-3; based on 100 parts by weight of the polyester polyol, the amount of the solvent in step (2) is 40-150 parts, preferably 40-141.6 parts.

[0062] The present invention does not specifically limit the dissolution method. In an embodiment of the present invention, the dissolution is carried out at 45 to 100°C, and can be specifically carried out at 45°C, 50°C, 60°C, 70°C, 80°C, 90°C and 100°C, and any temperature between the above values.

[0063] In some embodiments of the present invention, the polyurethane prepolymer solution and the thermoplastic polyurethane resin solution are allowed to cool to room temperature (ambient temperature, usually 20-40° C.) before proceeding to the next step.

[0064] After obtaining the polyurethane prepolymer solution and the thermoplastic polyurethane resin solution, the present invention mixes the thermoplastic polyurethane solution, a dynamic crosslinking agent, an adhesion promoter, a latent curing agent, an auxiliary agent and the polyurethane prepolymer solution to obtain the polyurethane coating solution.

[0065] The present invention has no special limitation on the mixing method, as long as the above components can be mixed evenly. In an embodiment of the present invention, a thermoplastic polyurethane solution is first mixed with a dynamic crosslinking agent, an adhesion promoter, a latent curing agent, and an auxiliary agent, and then mixed with the polyurethane prepolymer solution to obtain a polyurethane coating liquid. The present invention has no special limitation on the mixing method, as long as the above components can be mixed evenly. In an embodiment of the present invention, the mixing is stirring mixing, and the stirring speed is 10r / min to 500r / min, and the time is 0.5-1.5h.

[0066] In some embodiments of the present invention, when the solid content of the coating solution obtained in step (3) is low, the preparation method further comprises adding a solvent to adjust the solid content. In the present invention, those skilled in the art can select the type of solvent from the aforementioned solvents as needed to obtain a uniform polyurethane coating solution. In some embodiments of the present invention, the solvent used to adjust the solid content is a mixture of butanone and ethyl acetate, and the mass ratio of butanone to ethyl acetate is 2:1.

[0067] The present invention also provides use of the polyurethane coating liquid described in the above technical solution or the polyurethane coating liquid obtained by the preparation method described in the above technical solution in the preparation of barrier materials.

[0068] In some embodiments of the present invention, the barrier material is prepared from the polyurethane coating liquid. In some embodiments of the present invention, the thickness of the barrier material is 0.05-5 μm; the barrier layer material is prepared by coating the polyurethane coating liquid on a substrate and drying it.

[0069] In some embodiments of the present invention, the barrier material includes a primer layer and a barrier functional layer (referred to as the barrier layer for short), wherein the primer layer is in contact with the substrate, and the primer layer is prepared from the polyurethane coating liquid. In some embodiments of the present invention, in the thickness direction, the primer layer and the barrier functional layer are alternately arranged on the substrate. In some embodiments of the present invention, the thickness of the primer layer is 0.05 to 5 μm; the primer layer is prepared by coating the polyurethane coating liquid on a substrate and drying it. In the present invention, if the thickness of the primer layer is too small, the adhesion between the barrier functional layer and the substrate cannot be guaranteed, and if the thickness of the primer layer is too large, the thickness of the primer layer will be too high, the hardness will increase, and the rubbing resistance of the prepared high barrier material will deteriorate.

[0070] In some embodiments of the present invention, after the polyurethane coating liquid is coated on the substrate, the drying temperature may be 40°C-90°C, specifically 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, etc., and the drying time may be 0.5min-5min, specifically 0.5min, 1min, 2min, 3min, 4min, 5min, etc. Under the above temperature and time conditions, each component in the polyurethane coating liquid can achieve a good cross-linking hybridization effect, thereby ensuring excellent interlayer adhesion between the barrier material layer or the primer layer and the substrate, and greatly improving the flexibility and rubbing resistance of the barrier material.

[0071] The present invention has no particular limitation on the coating method, and any known coating method may be used, for example, roller coating, gravure coating, blade coating, slot coating, extrusion coating, air knife coating, dip coating, spray coating, etc.

[0072] The present invention has no special limitation on the substrate, and the polyurethane coating liquid can be used for various substrates, such as plastic films, paper bases, wooden boards, metal boards, fiber fabrics, textiles, composites composed of various materials, rubber materials, etc.

[0073] Figure 1 and Figure 2 Two structures of high barrier materials using the polyurethane coating of the present invention as the base coating are shown, wherein Figure 1 The high barrier material comprises a substrate 1, a primer layer 2 and a barrier layer 3. Figure 2 The high barrier material is a high barrier material prepared with fabric as a substrate, wherein the middle is a fabric 6, and both sides are coated with a primer layer 5 and a primer layer 7 respectively, and a barrier layer 4 and a barrier layer 8 are respectively arranged outside the primer layer.

[0074] More specifically, the high barrier material using the polyurethane coating of the present invention as the base coating can adopt the following structure:

[0075] Plastic film / / Base coating / / Oxide deposition layer,

[0076] Plastic film / / Base coating / / Metal deposition layer,

[0077] Barrier coating / / base coating / / fiber fabric / / base coating / / barrier coating,

[0078] Fabric / / Base Coating / / Barrier Coating,

[0079] Paper base / / Base coating / / Barrier coating,

[0080] Plastic film / / undercoat layer / / oxide deposit layer / / undercoat layer / / oxide deposit layer / / undercoat layer / / oxide deposit layer······etc.

[0081] The embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention. In addition, if not explicitly stated, all reagents used in the following embodiments are commercially available, or can be synthesized according to this article or known methods, and the reaction conditions not listed are also easily available to those skilled in the art.

[0082] Example 1

[0083] Preparation of polyurethane coating solution :

[0084] (1) 100 parts by weight of polycaprolactone polyol (number average molecular weight 500, hydroxyl value 10 mg KOH / g), 0.6 parts by weight of diphenylmethane diisocyanate, and 3.4 parts by weight of isophorone diisocyanate were added to 44.5 parts by weight of ethyl acetate, and the mixture was prepolymerized at 60° C. and 200 r / min with stirring for 1 h to obtain a polyurethane prepolymer solution.

[0085] (2) 15.0 parts by weight of a polyether thermoplastic polyurethane resin (number average molecular weight 50,000), 70.8 parts by weight of butanone and 70.8 parts by weight of ethyl acetate were mixed and stirred at 80° C. and 350 r / min until dissolved to obtain a polyether thermoplastic polyurethane resin solution.

[0086] (3) After the polyether thermoplastic polyurethane resin solution has cooled to room temperature, 1.00 part by weight of a dynamic crosslinking agent 2-phenylimidazole, 0.50 part by weight of an adhesion promoter tetraisopropoxytitanium, 0.2 part by weight of a latent curing agent (ALT-101), 0.40 part by weight of an antioxidant (antioxidant 1010) and 0.20 part by weight of an ultraviolet absorber (ultraviolet absorber 1130) are added, mixed with the polyurethane prepolymer solution at room temperature, and stirred at 200 r / min for 30 min to obtain a polyurethane coating liquid, recorded as DC-1, which has a solid content of 41.7% after testing.

[0087] Preparation of high barrier materials:

[0088] The polyurethane coating liquid DC-1 was coated on the surface of a polyethylene terephthalate (PET) substrate with a thickness of 12 μm using a micro-gravure coater and dried at 100°C for 2 minutes to obtain a primer layer with a thickness of 0.5 μm; then a 30 nm thick aluminum oxide barrier layer was evaporated on the surface of the primer layer to obtain a PET-based aluminum oxide barrier film.

[0089] The alumina barrier film was compounded with a 15 μm thick polyamide (PA) film and a 75 μm thick cast polypropylene (CPP) film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of each adhesive layer was 4 μm, and the structure of the packaging film was barrier film / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0090] Example 2

[0091] Preparation of polyurethane coating liquid:

[0092] (1) 100 parts by weight of isophthalic acid polyester polyol (number average molecular weight 130,000, hydroxyl value 210 mg KOH / g) and 30.0 parts by weight of toluene diisocyanate were added to 130.0 parts by weight of ethyl acetate, and the mixture was prepolymerized at 60° C. and 300 r / min with stirring for 1 h to obtain a polyurethane prepolymer solution.

[0093] (2) 4.5 parts by weight of a polyether thermoplastic polyurethane resin (number average molecular weight 100,000), 37.5 parts by weight of butanone and 37.5 parts by weight of ethyl acetate were mixed, and stirred at 80° C. and 350 r / min until dissolved to obtain a polyether thermoplastic polyurethane resin solution.

[0094] (3) After the polyether thermoplastic polyurethane resin solution is cooled to room temperature, 3.70 parts by weight of dynamic crosslinking agent 2-isopropyl imidazole, 14.50 parts by weight of adhesion promoter γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 7.10 parts by weight of latent curing agent (Alt-102), 2.40 parts by weight of antioxidant (antioxidant 1010) and 1.20 parts by weight of ultraviolet absorber (ultraviolet absorber 1130), 299.0 parts by weight of ethyl acetate and 149.5 parts by weight of butanone are added, mixed with the polyurethane prepolymer solution at room temperature, and stirred at 300 r / min for 30 min to obtain a polyurethane coating liquid, recorded as DC-2, with a solid content of 20% after testing.

[0095] Preparation of high barrier materials:

[0096] The polyurethane coating liquid DC-2 was coated on the surface of a PET substrate with a thickness of 12 μm using a micro-gravure coater and dried at 100°C for 2 minutes to obtain a primer layer with a thickness of 0.5 μm; then a 30 nm thick silicon oxide barrier layer was evaporated on the surface of the primer layer to obtain a PET-based silicon oxide barrier film.

[0097] The above-mentioned silicon oxide barrier film was compounded with a 15 μm thick PA film and a 75 μm thick CPP film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of each adhesive layer was 4 μm, and the structure of the packaging film was barrier film / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0098] Example 3

[0099] Preparation of polyurethane coating solution :

[0100] (1) 100 parts by weight of acrylic polyester polyol (number average molecular weight 100,000, hydroxyl value 100 mg KOH / g) and 0.3 parts by weight of toluene diisocyanate were added to 100.0 parts by weight of ethyl acetate, and the mixture was stirred for 1 h at 60° C. and 150 r / min for prepolymerization to obtain a polyurethane prepolymer solution.

[0101] (2) 11.3 parts by weight of a polyester thermoplastic polyurethane resin (number average molecular weight 70,000), 50.0 parts by weight of butanone and 50.0 parts by weight of ethyl acetate were mixed and stirred at 80° C. and 350 r / min until dissolved to obtain a polyester thermoplastic polyurethane resin solution.

[0102] (3) After the polyester thermoplastic polyurethane resin solution is cooled to room temperature, 3.08 parts by weight of a dynamic crosslinking agent 2-ethyl-4-methylimidazole, 3.33 parts by weight of an adhesion promoter γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.72 parts by weight of a latent curing agent (TP-820), 2.40 parts by weight of an antioxidant (antioxidant 1010) and 1.20 parts by weight of an ultraviolet absorber (ultraviolet absorber 1130) are added, mixed with the polyurethane prepolymer solution at room temperature, and stirred at 300 r / min for 30 min to obtain a polyurethane coating liquid, recorded as DC-3, with a solid content of 38.0% after testing.

[0103] Preparation of high barrier materials:

[0104] The polyurethane coating liquid DC-3 was coated on the surface of a PET substrate with a thickness of 12 μm using a micro-gravure coater, and dried at 100°C for 2 minutes to obtain a primer layer with a thickness of 0.5 μm; then, a polyvinylidene chloride (PVDC) high-barrier coating liquid (US Solvay A736) was coated on the surface of the primer layer, and after drying, a PET-based coated high-barrier film with a thickness of 0.5 μm was obtained.

[0105] The above-mentioned PET-based coated high-barrier film was compounded with a 15 μm thick PA film and a 75 μm thick CPP film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of each adhesive layer was 4 μm, and the structure of the packaging film was barrier film / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0106] Example 4

[0107] Preparation of polyurethane coating liquid:

[0108] (1) 100 parts by weight of polyadipate polyester polyol (number average molecular weight 50,000, hydroxyl value 10 mg KOH / g) and 3.0 parts by weight of toluene diisocyanate were added to 25 parts by weight of ethyl acetate, and the mixture was stirred for 1 h at 60° C. and 150 r / min for prepolymerization to obtain a polyurethane prepolymer solution.

[0109] (2) 4.5 parts by weight of a polyester thermoplastic polyurethane resin (number average molecular weight 100,000), 10 parts by weight of butanone and 30 parts by weight of ethyl acetate were mixed and stirred at 80° C. and 350 r / min until dissolved to obtain a polyester thermoplastic polyurethane resin solution.

[0110] (3) After the polyester thermoplastic polyurethane resin solution is cooled to room temperature, 3.70 parts by weight of a dynamic crosslinking agent 2-ethyl-4-methylimidazole, 8.33 parts by weight of an adhesion promoter γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 4.05 parts by weight of a latent curing agent (TP-820), 2.4 parts by weight of an antioxidant (antioxidant 1010) and 13.6 parts by weight of an ultraviolet absorber (ultraviolet absorber 1130) are added, mixed with the polyurethane prepolymer solution at room temperature, and stirred at 300 r / min for 30 min to obtain a polyurethane coating liquid, recorded as DC-4, with a solid content of 66.7% after testing.

[0111] Preparation of high barrier materials:

[0112] Adopt fiber cloth dip coating machine at 35g / m 2 The nylon fiber cloth was double-sided coated with polyurethane coating liquid DC-4 and dried at 100°C for 2 minutes to obtain a primer layer with a thickness of 2.5 μm on both sides; then PVDC high-barrier coating liquid (US Solvay A736) was coated on both sides of the nylon fiber cloth by a doctor blade coating process and dried at 120°C for 3 minutes, wherein the thickness of the barrier layer on both sides was 5 μm, to obtain a fiber fabric-based high-barrier material.

[0113] The above-mentioned fiber fabric-based high-barrier material is compounded with a 15 μm thick PA film and a 75 μm thick CPP film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of the adhesive layer between the barrier material and the PA film is 10 μm, and the thickness of the adhesive layer between the PA film and the CPP film is 4 μm, and the structure of the packaging film is barrier material / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0114] Example 5

[0115] Preparation of polyurethane coating liquid:

[0116] A polyurethane coating liquid was prepared according to the method in Example 1 and was recorded as DC-1.

[0117] Preparation of high barrier materials:

[0118] The polyurethane coating liquid DC-1 was coated on the surface of a PET substrate with a thickness of 12 μm using a micro-gravure coater and dried at 100°C for 2 minutes to obtain a primer layer with a thickness of 0.5 μm; then a 30 nm thick metal aluminum barrier layer was evaporated on the surface of the primer layer to obtain a PET-based aluminum-plated barrier film.

[0119] The above-mentioned PET-based aluminum-coated barrier film was compounded with a 15 μm thick PA film and a 75 μm thick CPP film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of each adhesive layer was 4 μm, and the structure of the packaging film was barrier film / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0120] Example 6

[0121] Preparation of polyurethane coating liquid:

[0122] (1) 100 parts by weight of isophthalic acid polyester polyol (number average molecular weight 65,000, hydroxyl value 110 mg KOH / g) and 0.3 parts by weight of diphenylmethane diisocyanate were added to 130 parts by weight of ethyl acetate, and the mixture was stirred for 1 hour at 60° C. and 300 r / min for prepolymerization to obtain a polyurethane prepolymer solution.

[0123] (2) 4.5 parts by weight of a polyether thermoplastic polyurethane resin (number average molecular weight 100,000), 37.5 parts by weight of butanone and 37.5 parts by weight of ethyl acetate were mixed, and stirred at 80° C. and 350 r / min until dissolved to obtain a polyether thermoplastic polyurethane resin solution.

[0124] (3) After the polyether thermoplastic polyurethane resin solution was cooled to room temperature, 3.7 parts by weight of a dynamic crosslinking agent 2-isopropyl imidazole, 14.5 parts by weight of an adhesion promoter γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 7.1 parts by weight of a latent curing agent (Alt-102), 0.17 parts by weight of an antioxidant (antioxidant 1010) and 1.2 parts by weight of an ultraviolet absorber (ultraviolet absorber 1130) were added, mixed with the polyurethane prepolymer solution at room temperature, and stirred at 300 r / min for 30 min to obtain a polyurethane coating liquid, recorded as DC-5, with a solid content of 39.5% after testing.

[0125] Preparation of high barrier materials:

[0126] The polyurethane coating liquid DC-5 was coated on the surface of a PET substrate with a thickness of 12 μm using a micro-gravure coater and dried at 100°C for 2 minutes to obtain a primer layer with a thickness of 0.5 μm. A 30 nm thick silicon oxide barrier layer was then evaporated on the surface of the primer layer to obtain a PET-based silicon oxide barrier film.

[0127] The barrier film was compounded with a 15 μm thick PA film and a 75 μm thick CPP film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of each adhesive layer was 4 μm, and the structure of the packaging film was barrier film / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0128] Comparative Example 1

[0129] After the surface of a PET substrate with a thickness of 12 μm was subjected to corona treatment (corona power of 3 kW, vehicle speed of 50 m / min), a 30 nm thick aluminum oxide barrier layer was evaporated to obtain a PET-based aluminum oxide barrier film.

[0130] The above-mentioned PET-based alumina barrier film was compounded with a 15 μm thick PA film and a 75 μm thick CPP film in a dry laminating machine using a cooking-resistant polyurethane adhesive to prepare a packaging film, wherein the thickness of each adhesive layer was 4 μm, and the structure of the packaging film was barrier film / / adhesive layer / / PA film / / adhesive layer / / CPP film.

[0131] Comparative Example 2

[0132] A polyurethane coating liquid was prepared by referring to the method of Example 1, which was marked as SC-1, except that no dynamic crosslinking agent was added.

[0133] A high barrier material (ie, packaging film) was prepared using the polyurethane coating solution (SC-1) according to the method in Example 1.

[0134] Comparative Example 3

[0135] A polyurethane coating liquid was prepared by referring to the method of Example 1, and was recorded as SC-2, except that no latent curing agent was added.

[0136] A high barrier material (ie, packaging film) was prepared using the polyurethane coating solution (SC-2) according to the method in Example 1.

[0137] Comparative Example 4

[0138] A polyurethane coating liquid was prepared by referring to the method of Example 1, and was recorded as SC-3, except that no dynamic crosslinking agent and latent curing agent were added.

[0139] A high barrier material (ie, packaging film) was prepared using the polyurethane coating solution (SC-3) according to the method in Example 1.

[0140] Comparative Example 5

[0141] A polyurethane coating liquid was prepared by referring to the method of Example 1, and was recorded as SC-4, except that no adhesion promoter was added.

[0142] A high barrier material (ie, packaging film) was prepared using the polyurethane coating solution (SC-4) according to the method in Example 1.

[0143] Comparative Example 6

[0144] A polyurethane coating liquid was prepared by referring to the method of Example 2, and was recorded as SC-5, except that the amount of toluene diisocyanate used was 33.3 parts by weight.

[0145] The polyurethane coating solution (SC-5) was used to prepare a high barrier material (ie, packaging film) according to the method in Example 2.

[0146] Performance Test:

[0147] 1. The water barrier properties, oxygen barrier properties and adhesion of the barrier layer (i.e. barrier film) of the packaging films prepared in the above Examples 1-6 and Comparative Examples 1-6 were tested by the methods of GB / T 21529-2008 "Determination of water vapor transmission rate of plastic films and sheets - Electrolytic sensor method", GB / T19789-2005 "Oxygen transmission test of plastic films and sheets for packaging materials - Coulometer test method" and GB / T9286-1998 "Scratch test for paints and varnishes". The results are shown in Table 1.

[0148] Table 1 Barrier film performance test

[0149]

[0150]

[0151] As shown in Table 1, the high barrier film materials or fiber-based flexible high barrier materials prepared by the polyurethane coating liquid of the present invention in Examples 1 to 6 all exhibit excellent oxygen and water barrier properties, and the adhesion of the barrier layer is level 0; while in Comparative Example 1, aluminum oxide is directly evaporated on the PET substrate, and the barrier property of the high barrier film prepared is much lower than that of Example 1, and the adhesion of the barrier layer is level 2, and the adhesion of the barrier layer is also significantly deteriorated. The substrate used in Example 3 is nylon fiber fabric, and the polyurethane coating liquid of the present invention is used as the primer, and then the barrier layer is coated, showing excellent oxygen and water barrier properties, indicating that the polyurethane coating liquid of the present invention has good adhesion to the fiber fabric substrate. Compared with the formula of the polyurethane coating liquid of Example 1, Comparative Examples 2, 3, 4, and 5 do not add dynamic crosslinking agent, latent curing agent, and adhesion promoter, resulting in poor oxygen and water barrier properties of the prepared barrier film, and poor adhesion of the barrier layer.

[0152] In summary, the polyurethane coating liquid of the present invention can be used on different substrates, and can effectively improve the adhesion of different types of barrier layers such as aluminum oxide, silicon oxide, metal-plated aluminum, barrier coatings, etc. to the substrate, and can also further improve the barrier properties of the prepared barrier film.

[0153] 2. Evaluation of packaging film’s boiling resistance

[0154] The packaging films prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were tested for boiling resistance according to the following method:

[0155] The packaging film was cut into 20cm×20cm sizes, and then the upper and lower layers were heat-sealed to form a packaging bag. Distilled water was put into the bag, and the air was removed and then sealed. Then, a pressure cooking treatment was carried out at 120°C for 30 minutes. After cooling, the packaging bag was taken out and the appearance was observed, and the oxygen permeability and water permeability of the packaging film after cooking were tested.

[0156] Table 2. Test and evaluation of the boiling resistance of packaging films

[0157]

[0158] The apparent changes of packaging films after cooking are divided into two categories:

[0159] After cooking, the packaging film has apparent problems such as delamination, bubbles, and damage, which are indicated by "×".

[0160] There is no change in the packaging film after steaming compared with before steaming, which is represented by "√".

[0161] As shown in Table 2, the packaging films of Examples 1 to 6 have good interlayer adhesion after cooking, and no delamination problem is found; among them, Examples 1, 2, 3, and 5 respectively use silicon oxide, aluminum oxide, barrier coating and metal aluminum as barrier functional layers, and no obvious attenuation occurs after cooking. Example 4 The polyurethane coating liquid of the present invention is coated on the nylon fiber cloth as a primer layer, and then the barrier layer is coated. The prepared packaging material has good interlayer adhesion after cooking, and good water and oxygen barrier properties. While Comparative Example 1 still uses aluminum oxide as a barrier layer, but because the primer layer prepared by the polyurethane coating liquid of the present invention is not used on the substrate, the prepared packaging film is delaminated after cooking, and the barrier performance cannot be tested. Comparative Examples 2 to 5 use the polyurethane coating liquid of the present invention to prepare the primer layer, but compared with Example 1, the polyurethane coating liquid does not add a dynamic crosslinking agent, a latent curing agent and an adhesion promoter. The packaging film is delaminated after cooking, and the barrier performance deteriorates, and it cannot even be tested. In Comparative Example 6 compared with Example 2, the weight ratio of polyester polyol to isocyanate is 100:33.3. Due to the increased degree of cross-linking between polyester polyol and isocyanate, the flexibility of the bottom layer deteriorates, thereby deteriorating its boiling resistance.

[0162] In summary, it is shown that the primer layer prepared by the polyurethane coating liquid of the present invention can effectively improve the boiling resistance of the high barrier layer.

[0163] 3. Evaluation of rubbing resistance of packaging film

[0164] The rubbing resistance of the packaging films prepared in Application Examples 1 to 6 and Comparative Examples 1 to 4 was tested using the method in ASTM F392-93, specifically:

[0165] The packaging film was cut into A4-sized samples and rubbed 270 times continuously on a rubbing test machine to test the oxygen barrier performance of the packaging material before and after rubbing. The results are shown in Table 3.

[0166] Table 3. Test and evaluation of rubbing resistance of packaging films

[0167]

[0168] After rubbing, the packaging film has apparent problems such as delamination, bubbles, and damage, which are indicated by "×".

[0169] There is no change in the interlayer adhesion of the packaging film after rubbing compared with before rubbing, which is represented by "√".

[0170] As shown in Table 3, the packaging films prepared in Examples 1 to 5 had good interlayer adhesion after being rubbed 270 times, and no delamination problem was found; among them, the substrates of Examples 1, 2, 3, 5, and 6 respectively used silicon oxide, aluminum oxide, PVDC high barrier material, metal aluminum, and silicon oxide as barrier functional layers, and no obvious attenuation occurred after being rubbed 270 times. In Example 4, the polyurethane coating liquid of the present invention was coated on the nylon fiber cloth to prepare a primer layer, and after the packaging material was prepared and rubbed 270 times, the water barrier property and oxygen barrier property were good. Comparative Example 1 still uses aluminum oxide as a barrier layer, but since the base layer prepared by the polyurethane coating liquid of the present invention is not used on the substrate, the prepared packaging film is delaminated after rubbing 270 times, and the barrier performance cannot be tested. The polyurethane coating liquid used in Comparative Examples 2 to 6 is used to prepare the base layer, but the polyurethane coating liquid in Comparative Examples 2 to 5 does not use a dynamic crosslinking agent, a latent curing agent, or an adhesion additive. The ratio of polyester polyol to diisocyanate in the polyurethane coating liquid in Comparative Example 6 exceeds the scope of this application. The packaging films obtained in Comparative Examples 2 to 6 are delaminated after rubbing 270 times, and the barrier performance cannot be tested. This shows that the base layer prepared by the polyurethane coating liquid of the present invention can effectively improve the boiling resistance of the high barrier layer.

[0171] The above description is only a preferred embodiment of the present invention and does not limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyurethane coating liquid is prepared from the following components in parts by weight: 100 parts of polyester polyol, 0.3-30.0 parts of isocyanate, 4.5-15.0 parts of thermoplastic polyurethane resin, 0.01-3.70 parts of dynamic crosslinking agent, 0.06-14.50 parts of adhesion promoter, 0.06-7.10 parts of latent curing agent, 0-20.00 parts of auxiliary agent, and 40-850 parts of solvent.

2. The polyurethane coating liquid according to claim 1, characterized in that The polyester polyol comprises at least one of aliphatic polyester polyol, aromatic polyester polyol and mixed acid polyester polyol; the number average molecular weight of the polyester polyol is 300 to 150,000, and the hydroxyl value is 0.1 mg KOH / g to 250 mg KOH / g; The isocyanate includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, dicyclohexylmethane diisocyanate trimer and methylcyclohexyl diisocyanate trimer.

3. The polyurethane coating liquid according to claim 1, characterized in that: The thermoplastic polyurethane resin includes at least one of polycarbonate polyurethane resin, polyolefin polyurethane resin, polyether polyurethane resin and polyester polyurethane resin, wherein the number average molecular weight of the thermoplastic polyurethane resin is 5,000 to 100,000.

4. The polyurethane coating liquid according to claim 1, characterized in that: The dynamic cross-linking agent includes at least one of 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-isopropylimidazole and 1,5,7-triazabicyclo[4.4.0]dec-5-ene; The latent curing agent includes at least one of an imine latent curing agent and an oxazolidine latent curing agent.

5. The polyurethane coating liquid according to claim 1, characterized in that: The adhesion promoter includes at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent and a zirconate coupling agent.

6. The polyurethane coating liquid according to claim 1, characterized in that: The auxiliary agent includes at least one of an antioxidant, an anti-ultraviolet agent and a leveling agent.

7. A method for preparing the polyurethane coating solution according to any one of claims 1 to 6, comprising the following steps: (1) mixing polyester polyol, isocyanate and solvent, and performing prepolymerization reaction to obtain a polyurethane prepolymer solution, (2) dissolving a thermoplastic polyurethane resin in a solvent to obtain a thermoplastic polyurethane resin solution, (3) mixing the thermoplastic polyurethane solution, a dynamic crosslinking agent, an adhesion promoter, a latent curing agent, an auxiliary agent and the polyurethane prepolymer solution to obtain the polyurethane coating solution, in, There is no limitation on the order of step (1) and step (2).

8. Use of the polyurethane coating liquid according to any one of claims 1 to 6 or the polyurethane coating liquid obtained by the preparation method according to claim 7 in the preparation of barrier materials.

9. The use according to claim 8, characterized in that The barrier material is prepared from the polyurethane coating liquid.

10. The use according to claim 8, characterized in that The barrier material comprises a primer layer and a barrier function layer, wherein the primer layer is in contact with a substrate and the primer layer is prepared from the polyurethane coating liquid.

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