Polyurethane adhesive film as well as preparation method and application thereof

Abstract

The invention relates to a polyurethane adhesive film as well as a preparation method and application thereof. The polyurethane adhesive film is prepared from the following raw materials in parts by weight: 30 to 55 parts of diisocyanate, 20 to 45 parts of polyol, 5 to 18 parts of a chain extender, 0.5 to 3 parts of a catalyst, 0.8 to 6 parts of a functional auxiliary agent, 10 to 50 parts of a special adhesive material and 0.05 to 5 parts of a cross-linking agent. The polyurethane adhesive film provided by the invention has excellent peeling strength while ensuring excellent physical and mechanical properties, and can be well applied to sealing and bonding of various special base materials.

Description

Technical Field

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

[0002] Polyurethane, a polymer material with a thermoplastic linear structure, has attracted widespread attention for its exceptional chemical resistance and mechanical properties. Films made from polyurethane, due to their superior physical properties such as high elasticity, toughness, tear resistance, strong adhesion, abrasion resistance, weather resistance, and wide applicability, have found widespread application in a variety of industries, including luggage, footwear, packaging, textiles, electronics, automotive, and medical devices.

[0003] However, when polyurethane film is used on special substrates with flame retardant, water-repellent, antistatic, anti-UV or electromagnetic shielding properties, due to the different structures (such as non-polar or weak polarity) in the special substrates or the addition of functional additives, it is difficult for the polyurethane film to form a tightly entangled state on the surface of the special substrate, thereby reducing the adhesion performance of the polyurethane film in subsequent processing steps.

[0004] Therefore, it is of great significance to design a polyurethane film that can inherit the excellent physical and mechanical properties of the original polyurethane film and is suitable for sealing and bonding a variety of special substrates. Summary of the Invention

[0005] To address the above technical issues, the present invention provides a polyurethane film, its preparation method, and its application. The polyurethane film of the present invention exhibits semi-plastic and semi-solid properties, ensuring excellent physical and mechanical properties while also exhibiting superior peel strength, making it well-suited for sealing and bonding a variety of special substrates.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a polyurethane film, wherein the raw materials for preparing the polyurethane film include the following components in parts by weight:

[0008]

[0009] The present invention designs the raw materials for preparing polyurethane films. By compounding a special adhesive material, a crosslinking agent, and other raw material components, the resulting polyurethane film exhibits semi-plastic, semi-solid properties. This film maintains excellent physical and mechanical properties while also exhibiting exceptional peel strength, making it well-suited for sealing and bonding a variety of special substrates. This effectively addresses the existing issue of poor polyurethane film adhesion, often caused by the non-polar or weakly polar structure of the substrate or the addition of functional additives.

[0010] The weight percentage of the special adhesive material in the raw materials for preparing the polyurethane film provided by the present invention can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the said range.

[0011] The weight percentage of the cross-linking agent can be 0.05 parts, 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 parts, 2 parts, 3 parts, 4 parts or 5 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0012] The weight proportions of the diisocyanate may be 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts, 45 parts, 48 parts, 50 parts, 52 parts or 55 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range.

[0013] The weight proportions of the polyol can be 20 parts, 23 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts or 45 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0014] The weight percentage of the chain extender can be 5 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts or 18 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0015] The weight proportions of the catalyst can be 0.5 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts or 3 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0016] The weight percentage of the functional additive can be 0.8 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts or 6 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0017] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0018] As a preferred technical solution of the present invention, the special adhesive material is a resin containing active groups.

[0019] The active group includes any one of a hydroxyl group, an unsaturated double bond, an ester group or an epoxy group, or a combination of at least two of them.

[0020] As a preferred technical solution of the present invention, the number average molecular weight of the special adhesive material is 2000-8000, for example, it can be 2000, 3000, 4000, 5000, 6000, 7000 or 8000, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the said range.

[0021] By controlling the number average molecular weight of the special adhesive material within a specific range, the present invention can better crosslink the molecular segments of the special adhesive material and the polyurethane, thereby improving the cohesive strength of the colloid and forming a more stable network structure, thereby obtaining a polyurethane film with excellent mechanical properties. At the same time, the active groups in the special adhesive material with a specific number average molecular weight are more likely to form hydrogen bonds with the bonding surface, thereby reducing the adverse effects of the non-polar or weakly polar structure and functional additives on the surface of the special substrate, thereby obtaining a polyurethane film with even better bonding properties. When the number average molecular weight is too low or too high, the mechanical properties and peel strength of the resulting polyurethane film will be reduced. Among them, if the number average molecular weight is too low, the melting point of the polyurethane film will be lowered, and the physical crosslinking network formed will be sparse, making it easy to produce glue overflow during the thermal processing process, thereby reducing its bonding properties. If the number average molecular weight is too high, the melting point of the polyurethane film will increase, and the physical cross-linking network formed will be too tight, resulting in the subsequent bonding temperature of the polyurethane film being too high, increasing the difficulty of post-processing of the product, and the film is prone to debonding and cracking on special substrates.

[0022] Preferably, the special adhesive material includes any one of acrylic resin, phenolic resin, unsaturated polyester resin or epoxy resin, or a combination of at least two of them.

[0023] As a preferred technical solution of the present invention, the special adhesive material is a combination of acrylic resin and phenolic resin.

[0024] The present invention adopts a combination of acrylic resin and phenolic resin as the special adhesive material, so that when the two are combined with other raw material components, they can form a high-strength and stable mutual transmission network structure, thereby being able to exert a synergistic effect and thus obtain a polyurethane film with better bonding and mechanical properties.

[0025] As a preferred technical solution of the present invention, the mass ratio of the acrylic resin to the phenolic resin is 1:(0.5-2), wherein (0.5-2) can be, for example, 0.5, 0.8, 1, 1.2, 1.4, 1.6, 1.8 or 2, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the said range.

[0026] The present invention can achieve a better mutual penetration effect between the linear or slightly cross-linked chains of polyurethane, phenolic resin and methacrylic resin by controlling the mass ratio of acrylic resin and phenolic resin within a specific range, thereby forming a higher strength and stable mutual transmission network structure, thereby obtaining a polyurethane film with better mechanical and adhesive properties. When the mass ratio of the two is too high or too low, the penetration effect will deteriorate, thereby reducing the mechanical properties and peel strength of the obtained polyurethane film. At the same time, if the mass ratio of the two is too low, that is, the phenolic resin content is relatively high, the shrinkage stress of the polyurethane film during subsequent curing will increase, thereby increasing the risk of cracking; if the mass ratio of the two is too high, that is, the methacrylic resin content is relatively high, the thermal processing process of the polyurethane film is prone to glue overflow, resulting in low bonding strength, and the adhesive layer may fall off after bonding due to its lack of high temperature resistance.

[0027] Preferably, the cross-linking agent includes any one of an isocyanate cross-linking agent, an amine cross-linking agent or an acid anhydride cross-linking agent, or a combination of at least two of them, preferably a combination of an amine cross-linking agent and an acid anhydride cross-linking agent.

[0028] The present invention further optimizes the cross-linking agent to be a combination of an amine cross-linking agent and an acid anhydride cross-linking agent. When compounded with raw material components such as special adhesive materials, the state of uncross-linked and entangled cross-linking sites of some special adhesive materials caused by a single cross-linking agent can be reduced, and the cured cross-linking state of different special adhesive materials can be enhanced respectively, thereby achieving a good synergistic effect and obtaining a polyurethane film with better mechanical properties and bonding properties.

[0029] It should be noted that, in the present invention, there is no special limitation on the type of cross-linking agent, including isocyanate cross-linking agents, amine cross-linking agents and acid anhydride cross-linking agents. The commonly used isocyanate cross-linking agents, amine cross-linking agents and acid anhydride cross-linking agents in the art are all applicable.

[0030] The amine cross-linking agent illustratively includes, but is not limited to, ethylenediamine, diethylenetriamine, toluenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, and N,N'-methylenebisacrylamide.

[0031] The anhydride cross-linking agent illustratively includes, but is not limited to, maleic anhydride, itaconic anhydride, succinic anhydride, phthalic anhydride, and polystyrene-maleic anhydride copolymer.

[0032] Preferably, the mass ratio of the amine crosslinker to the anhydride crosslinker is 1:(0.5-2), wherein (0.5-2) can be, for example, 0.5, 0.8, 1, 1.2, 1.4, 1.6, 1.8 or 2, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0033] In the present invention, by regulating the mass ratio of the amine crosslinker and the acid anhydride crosslinker in the crosslinker, it can be well compounded with components such as special adhesive materials, thereby further improving the mechanical properties and bonding properties of the obtained polyurethane film.

[0034] It should be noted that, in the present invention, there is no particular limitation on the type of diisocyanate, and all diisocyanates commonly used in the art are applicable. The diisocyanates illustratively include, but are not limited to, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), meta-xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), tetramethylxylylene diisocyanate (TMXDI), isophorone diisocyanate (IPDI), and 1,5-naphthalene diisocyanate (NDI).

[0035] Preferably, the polyol includes any one or a combination of at least two of tetrahydrofuran-propylene oxide copolymer glycol, polyoxypropylene-ethylene oxide glycol, polyneopentyl adipate, polycarbonate diol, polyethylene adipate, polybutylene adipate, polyethylene glycol or polycaprolactone diol.

[0036] Preferably, the chain extender includes any one of 4,4'-bismaleimidodiphenylmethane, propylene glycol, ethanolamine, or 3,5-diaminoisobutyl chlorobenzoate, or a combination of at least two thereof.

[0037] Preferably, the catalyst comprises any one of an organotin catalyst, an organobismuth catalyst or an organopotassium catalyst, or a combination of at least two thereof.

[0038] Preferably, the organotin catalyst includes any one of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, di-n-octyltin dilaurate or tin methyl mercaptan, or a combination of at least two thereof.

[0039] Preferably, the organic bismuth catalyst includes any one of bismuth carboxylate, bismuth isooctanoate or DY-20, or a combination of at least two thereof.

[0040] Preferably, the organic potassium catalyst includes any one of potassium octoate, potassium acetate or potassium neodecanoate, or a combination of at least two thereof.

[0041] Preferably, the functional auxiliary agent includes any one of an ultraviolet light absorber, an antioxidant or an anti-hydrolysis agent, or a combination of at least two thereof.

[0042] Preferably, the functional auxiliary agent is a combination of an ultraviolet light absorber, an antioxidant and an anti-hydrolysis agent.

[0043] Preferably, the weight portion of the ultraviolet light absorber is 0.2-1 part, for example, it can be 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part or 1 part, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0044] It should be noted that, in the present invention, there is no particular limitation on the type of ultraviolet absorber, and any ultraviolet absorber commonly used in the art is applicable. The ultraviolet absorber illustratively includes, but is not limited to, benzophenone ultraviolet absorbers (UV-9, UV-49, UV-531), benzotriazole ultraviolet absorbers (UV-234, UV-320, UV-327, UV-328, UV-329, UV-1130, UV-1300, UV-5411), and cyanoacrylate anti-ultraviolet agents (UV-3030, UV-3035, UV-3039).

[0045] Preferably, the weight portion of the antioxidant is 0.1-2 parts, for example, it can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts or 2 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0046] It should be noted that, in the present invention, there is no particular limitation on the type of antioxidant, and any antioxidant commonly used in the art is applicable. The antioxidants illustratively include, but are not limited to, resorcinol (M-benzene), antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant TPP, and antioxidant B215.

[0047] Preferably, the weight ratio of the anti-hydrolysis agent is 0.5-3 parts, for example, it can be 0.5 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts or 3 parts, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0048] It should be noted that in the present invention, there is no special limitation on the type of anti-hydrolysis agent, and any anti-hydrolysis agent commonly used in the art is applicable. The anti-hydrolysis agent exemplarily includes but is not limited to: The anti-hydrolysis agent exemplarily includes but is not limited to: polycarbodiimide, carbodiimide.

[0049] In a second aspect, the present invention provides a method for preparing the polyurethane film according to the first aspect, wherein the method comprises the following steps:

[0050] The polyurethane film is obtained by mixing diisocyanate, polyol, chain extender, catalyst, functional additive, special adhesive material and cross-linking agent, and then subjecting the mixture to melt extrusion and casting treatment.

[0051] In the present invention, the polyurethane film produced by blending the various raw material components, followed by melt extrusion and casting, maintains excellent physical and mechanical properties while also exhibiting enhanced adhesive properties. Compared to methods that first prepare a polyurethane prepolymer, then add other raw material components and mix them, followed by direct casting and casting to produce the polyurethane film, the production cycle is shorter, allowing for the production of a larger number of samples at once, reducing factors such as uncontrollable batch-to-batch quality. Furthermore, secondary melting is effectively avoided, which can cause the polyurethane molecular chains to elongate, expand, or even break under high temperature and high shear, leading to a decrease in molecular weight and, in turn, to deteriorate the mechanical and adhesive properties of the polyurethane film. Furthermore, the prepolymer method suffers from a long production cycle.

[0052] Preferably, the melt extrusion temperature is 160-220°C, for example, it can be 160°C, 170°C, 180°C, 190°C, 200°C, 210°C or 220°C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0053] Preferably, the melt extrusion pressure is 10-25 MPa, for example, it can be 10 MPa, 12 MPa, 15 MPa, 18 MPa, 20 MPa, 22 MPa or 25 MPa, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0054] Preferably, the melt extrusion is carried out in a twin-screw extruder.

[0055] Preferably, the rotational speed of the twin-screw extruder is 15-110 rpm, for example, it can be 15 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm or 110 rpm, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0056] Preferably, the casting process further includes a cooling and molding step.

[0057] Preferably, the cooling forming method includes using a cooling roller for cooling forming.

[0058] Preferably, the cooling molding temperature is 10-45°C, for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C or 45°C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0059] Exemplarily, the method for preparing the polyurethane film specifically includes the following steps:

[0060] Diisocyanate, polyol, chain extender, catalyst, functional additive, special adhesive material and cross-linking agent are mixed and melt-extruded to obtain a molten mixed colloid at an extrusion temperature of 160-220°C, an extrusion pressure of 10-25 MPa and a rotation speed of 15-110 rpm. The molten mixed colloid is then cast and cooled at 10-45°C to obtain the polyurethane film.

[0061] The present invention designs the raw materials for preparing the polyurethane film and can obtain a polyurethane film with excellent bonding performance through a simple preparation process, eliminating the complex steps of additionally treating the substrate with special solvents or plasma to improve the adhesion of traditional polyurethane films, thereby simplifying the production process, thereby improving production efficiency and reducing production costs.

[0062] In a third aspect, the present invention provides a use of the polyurethane film as described in the first aspect in luggage, footwear, packaging, textiles, electronics, automobiles or medical equipment.

[0063] Compared with the prior art, the present invention has at least the following beneficial effects:

[0064] The present invention designs the raw materials for preparing the polyurethane film. By combining a special adhesive material, a crosslinking agent, and other components, a polyurethane film with semi-plastic and semi-solid properties is obtained. While maintaining excellent physical and mechanical properties (low-temperature tensile strength retention of 74-93%, hydrolysis-resistant tensile strength retention of 76-92%, tensile elongation of 327-654%, flexural resistance of 50,000-100,000 times, and low-temperature flexural resistance of 30,000-60,000 times), the film also exhibits excellent peel strength (1.2-3.3 kgf / cm), making it well suited for sealing and bonding a variety of special substrates. This effectively solves the problem in the prior art of poor cohesiveness of polyurethane films caused by the non-polar or weakly polar structure of the substrate or the addition of functional additives. DETAILED DESCRIPTION

[0065] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0066] Unless otherwise specified, the raw materials or reagents used in the following examples and comparative examples are commercially available products. Some raw material information is as follows:

[0067] Polyoxypropylene-oxyethylene glycol: purchased from Jiangsu Jinkailun Textile Technology Co., Ltd., brand Jiangsu Jinkailun;

[0068] Polyethylene glycol: purchased from Shandong Hairui New Materials Co., Ltd. 0901;

[0069] Methacrylate resin: purchased from Guangdong Huolun Building Materials Technology Development Co., Ltd., brand: Naiboshi;

[0070] Phenolic resin: purchased from Shandong Maofa Chemical Co., Ltd. 230324;

[0071] Unsaturated polyester resin: purchased from ZC-196 of Zhongchuan Technology Co., Ltd.

[0072] Epoxy resin: NPEL-128 purchased from Wanqing Chemical Technology Co., Ltd.

[0073] Example 1

[0074] This embodiment provides a polyurethane film, and the preparation method thereof specifically includes the following steps:

[0075] 30 kg of diphenylmethane diisocyanate, 25 kg of polyoxypropylene-ethylene oxide glycol, 5 kg of chain extender 4,4'-bismaleimide diphenylmethane, 1 kg of stannous octoate, 0.5 kg of ultraviolet absorber (UV-3290.25 kg, UV-130000.25 kg), 0.2 kg of M-benzenediol, 0.8 kg of polycarbodiimide, 34 kg of special adhesive material (number average molecular weight of 4000, mass ratio of methacrylic resin to phenolic resin of 1:1), and 3 kg of cross-linking agent (mass ratio of maleic anhydride to ethylenediamine of 1:1) were mixed and melt-extruded through a twin-screw extruder to obtain a molten mixed colloid. The extrusion temperature was 160 ° C, the extrusion pressure was 15 MPa, and the rotation speed was 20 rpm. The molten mixed colloid was then cast and cooled at 20 ° C by a cooling roller to obtain the polyurethane film.

[0076] Example 2

[0077] This embodiment provides a polyurethane film, and the preparation method thereof specifically includes the following steps:

[0078] 42 kg of toluene diisocyanate, 35 kg of polyoxypropylene-ethylene oxide glycol, 6 kg of chain extender (4 kg of 4,4'-bismaleimide diphenylmethane, 2 kg of ethanolamine), 2 kg of potassium octoate, 0.2 kg of UV-49, 1 kg of antioxidant 168, 2 kg of hydrolysis-resistant carbodiimide, 50 kg of unsaturated polyester resin, and 0.05 kg of itaconic anhydride were mixed and melt-extruded through a twin-screw extruder to obtain a molten mixed colloid. The extrusion temperature was 180° C., the extrusion pressure was 10 MPa, and the rotation speed was 65 rpm. The molten mixed colloid was then cast and cooled on a cooling roller at 10° C. to obtain the polyurethane film.

[0079] Example 3

[0080] This embodiment provides a polyurethane film, and the preparation method thereof specifically includes the following steps:

[0081] 55 kg of isophorone diisocyanate, 45 kg of polyethylene glycol, 18 kg of chain extender 4,4'-bismaleimide diphenylmethane, 3 kg of bismuth carboxylate, 1 kg of UV-3030, 2 kg of antioxidant 1010, 3 kg of hydrolysis-resistant agent polycarbodiimide, 10 kg of epoxy resin, and 5 kg of m-phenylenediamine were mixed and melt-extruded through a twin-screw extruder to obtain a molten mixed colloid at an extrusion temperature of 220° C., an extrusion pressure of 25 MPa, and a rotation speed of 110 rpm. The molten mixed colloid was then cast and cooled on a cooling roller at 45° C. to obtain the polyurethane film.

[0082] Example 4

[0083] This embodiment provides a polyurethane film, which differs from Example 1 only in that the number average molecular weight of the special adhesive material in Example 1 is adjusted from 4000 to 1000, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0084] Example 5

[0085] This embodiment provides a polyurethane film, which differs from Example 1 only in that the number average molecular weight of the special adhesive material in Example 1 is adjusted from 4000 to 2000, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0086] Example 6

[0087] This embodiment provides a polyurethane film, which differs from Example 1 only in that the number average molecular weight of the special adhesive material in Example 1 is adjusted from 4000 to 8000, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0088] Example 7

[0089] This embodiment provides a polyurethane film, which differs from Example 1 only in that the number average molecular weight of the special adhesive material in Example 1 is adjusted from 4000 to 10000, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0090] Example 8

[0091] This embodiment provides a polyurethane film, which differs from Example 1 only in that methacrylic resin is not added and the reduced weight portion thereof is allocated to phenolic resin. Other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0092] Example 9

[0093] This embodiment provides a polyurethane film, which differs from Example 1 only in that no phenolic resin is added, and the reduced weight portion thereof is allocated to methacrylic resin. Other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0094] Example 10

[0095] This embodiment provides a polyurethane film, which differs from Example 1 only in that the mass ratio of methacrylic resin to phenolic resin in Example 1 is adjusted from 1:1 to 1:0.25, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0096] Example 11

[0097] This embodiment provides a polyurethane film, which differs from Example 1 only in that the mass ratio of methacrylic resin to phenolic resin in Example 1 is adjusted from 1:1 to 0.5, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0098] Example 12

[0099] This embodiment provides a polyurethane film, which differs from Example 1 only in that the mass ratio of methacrylic resin to phenolic resin in Example 1 is adjusted from 1:1 to 1:2, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0100] Example 13

[0101] This embodiment provides a polyurethane film, which differs from Example 1 only in that the mass ratio of methacrylic resin to phenolic resin in Example 1 is adjusted from 1:1 to 1:2.5, and other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0102] Example 14

[0103] This embodiment provides a polyurethane film, which differs from Example 1 only in that maleic anhydride is not added to the cross-linking agent of Example 1, and its reduced mass is allocated to ethylenediamine. Other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0104] Example 15

[0105] This embodiment provides a polyurethane film, which differs from Example 1 only in that ethylenediamine is not added to the cross-linking agent of Example 1, and its reduced mass is allocated to maleic anhydride. Other raw materials, addition amounts and preparation methods are the same as those in Example 1.

[0106] Example 16

[0107] This embodiment provides a polyurethane film, and the preparation method thereof specifically includes the following steps:

[0108] (1) 30 kg of diphenylmethane diisocyanate, 25 kg of polyoxypropylene-ethylene oxide glycol, and 1 kg of stannous octoate were mixed at 80° C. for 1 hour to obtain a polyurethane prepolymer;

[0109] (2) adding 5 kg of chain extender 4,4'-bismaleimide diphenylmethane to the polyurethane prepolymer described in step (1) and continuing stirring for 4 hours, then adding 0.5 kg of ultraviolet light absorber (0.25 kg of UV-329 and 0.25 kg of UV-1300), 0.2 kg of M-benzene, 0.8 kg of polycarbodiimide, 34 kg of special adhesive material (number average molecular weight of 3000, mass ratio of methacrylic resin to phenolic resin of 1:1), and 3 kg of crosslinking agent (mass ratio of maleic anhydride to ethylenediamine of 1:1) and mixing to obtain a mixed colloid;

[0110] (3) The mixed colloid obtained in step (2) is cast onto a polytetrafluoroethylene mold, and after being subjected to a casting process, it is cooled and formed by a cooling roller at 20° C. to obtain the polyurethane film.

[0111] Comparative Example 1

[0112] This comparative example provides a polyurethane film, which differs from Example 1 only in that the special adhesive material in Example 1 is replaced by a polypropylene resin of equal mass (purchased from Xinersheng Plastic Raw Materials (Dongguan) Co., Ltd. Z30S), and other raw materials, contents and preparation methods are the same as those in Example 1.

[0113] The polyurethane films obtained in Examples 1-16 and Comparative Example 1 were subjected to performance tests, and the test methods / standards are as follows:

[0114] (1) Low-temperature tensile strength retention, hydrolysis-resistant tensile strength retention, and tensile elongation are tested according to ASTM-D412 (Type C);

[0115] (2) Flexibility: Tested at 23°C according to SATRA TM25;

[0116] (3) Low temperature flexural resistance: tested at -20°C with reference to SATRA TM25;

[0117] (4) Peel strength: Tested according to ASTM F2029.

[0118] The test results are shown in Table 1.

[0119] Table 1

[0120]

[0121]

[0122] The test results show that:

[0123] (1) It can be seen from Examples 1 to 16 that the present invention designs the raw materials and methods for preparing the polyurethane film, and adopts special adhesive materials, cross-linking agents and other components to obtain a polyurethane film with semi-plastic and semi-solid properties, with a low-temperature tensile strength retention rate of 74-93%, a hydrolysis-resistant tensile strength retention rate of 76-92%, a tensile elongation of 327-654%, a flexural resistance of 50,000 to 100,000 times, a low-temperature flexural resistance of 30,000 to 60,000 times, and a peel strength of 1.2-3.3 kgf / cm.

[0124] (2) By comparing Example 1 with Examples 4-7, it can be seen that Example 4 uses a special adhesive material with a number average molecular weight of less than 2000, while Example 7 uses a special adhesive material with a number average molecular weight of more than 8000. The peel strengths of the polyurethane films obtained by the two methods are significantly reduced, and their mechanical properties show a deterioration effect, especially the tensile elongation and low-temperature tensile strength retention rate are significantly reduced. This shows that the present invention can obtain a polyurethane film with better bonding and mechanical properties by further regulating the number average molecular weight of the special adhesive material.

[0125] (3) The comparison between Example 1 and Examples 8 and 9 shows that the special adhesive materials in Examples 8 and 9 are both single resins, and the peel strength and mechanical properties of the polyurethane films obtained by the two are significantly worse than those in Example 1. This shows that the present invention further optimizes the special adhesive material to be a combination of acrylic resin and phenolic resin, so that the two can play a synergistic role when combined with other raw material components, thereby making the obtained polyurethane film have better bonding properties and mechanical properties. When any one of them is missing, the corresponding technical effect is significantly worse.

[0126] (4) The comparison between Examples 1, 8 and 9 and 10-13 of the present invention shows that the mass ratio of methacrylic resin to phenolic resin used in Examples 10 and 13 exceeds the preferred mass ratio range of 1: (0.5-1.2), and the mechanical properties (especially the fracture growth rate) and peel strength of the obtained polyurethane film are significantly worse than those of Example 1, but higher than those of Examples 8 and 9. This shows that the present invention further optimizes the mass ratio of acrylic resin and phenolic resin based on the special adhesive material of the combination of the two, and can obtain a polyurethane film with better mechanical properties and bonding properties.

[0127] (5) The comparison between Example 1 and Examples 14 and 15 shows that the crosslinking agent used in Examples 14 and 15 is a single crosslinking agent, and the peel strength and mechanical properties of the polyurethane films obtained by the two are worse than those in Example 1, indicating that the present invention can play a good synergistic role when compounding with raw material components such as special adhesive materials by further optimizing the crosslinking agent to a combination of amine crosslinking agents and acid anhydride crosslinking agents, thereby obtaining a polyurethane film with better mechanical properties and bonding properties. When any one of them is missing, the corresponding technical effect becomes worse.

[0128] (6) From the comparison between Example 1 and Example 16, it can be seen that the present invention can obtain a polyurethane film with better adhesive properties and mechanical properties by designing the preparation method of the polyurethane film.

[0129] (7) By comparing Example 1 with Comparative Example 1, it can be seen that Comparative Example 1 uses conventional resin materials to replace the special adhesive material component in Example 1, and the peel strength of the polyurethane film obtained is only 0.9 kgf / cm, and its mechanical properties are significantly deteriorated. That is, it is impossible to achieve the technical effect of the present invention of having excellent peel strength while ensuring excellent physical and mechanical properties.

[0130] In summary, the present invention designs the raw materials and methods for preparing polyurethane films. By selecting special adhesive materials and cross-linking agents, they can be better compounded with other components. Furthermore, a polyurethane film with excellent mechanical properties and excellent peel strength is prepared through a specific preparation method, which can be well used in the sealing and bonding of various special substrates, effectively solving the problem in the prior art of poor bonding performance of polyurethane films due to the non-polar or weakly polar structure of the substrate or the addition of functional additives.

[0131] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A polyurethane film, characterized in that: The raw materials for preparing the polyurethane film include the following components in parts by weight:

2. The polyurethane film according to claim 1, characterized in that The special adhesive material is a resin containing active groups; The active group includes any one or a combination of at least two of a hydroxyl group, an unsaturated double bond, an ester group or an epoxy group; Preferably, the number average molecular weight of the special adhesive material is 2000-8000; Preferably, the special adhesive material includes any one of acrylic resin, phenolic resin, unsaturated polyester resin or epoxy resin, or a combination of at least two thereof; Preferably, the special adhesive material is a combination of acrylic resin and phenolic resin; Preferably, the mass ratio of the acrylic resin to the phenolic resin is 1:(0.5-2).

3. The polyurethane film according to claim 1 or 2, characterized in that: The cross-linking agent includes any one of an isocyanate cross-linking agent, an amine cross-linking agent or an acid anhydride cross-linking agent, or a combination of at least two of them, preferably a combination of an amine cross-linking agent and an acid anhydride cross-linking agent.

4. The polyurethane film according to any one of claims 1 to 3, characterized in that: The polyol includes any one of tetrahydrofuran-propylene oxide copolymer glycol, polyoxypropylene-ethylene oxide glycol, polyneopentyl adipate, polycarbonate diol, polyethylene adipate, polybutylene adipate, polyethylene glycol or polycaprolactone diol, or a combination of at least two thereof.

5. The polyurethane film according to any one of claims 1 to 4, characterized in that: The chain extender includes any one of 4,4'-bismaleimide diphenylmethane, propylene glycol, ethanolamine, or 3,5-diamino-p-chlorobenzoic acid isobutyl ester, or a combination of at least two thereof.

6. The polyurethane film according to any one of claims 1 to 5, characterized in that: The catalyst includes any one of an organic tin catalyst, an organic bismuth catalyst or an organic potassium catalyst, or a combination of at least two of them.

7. The polyurethane film according to any one of claims 1 to 6, characterized in that: The functional additive includes any one or a combination of at least two of an ultraviolet light absorber, an antioxidant or a hydrolysis-resistant agent; Preferably, the functional additive is a combination of an ultraviolet light absorber, an antioxidant and an anti-hydrolysis agent; Preferably, the weight portion of the ultraviolet light absorber is 0.2-1 part; Preferably, the antioxidant is present in an amount of 0.1-2 parts by weight; Preferably, the weight portion of the anti-hydrolysis agent is 0.5-3 parts.

8. A method for preparing a polyurethane film according to any one of claims 1 to 7, characterized in that: The preparation method specifically comprises the following steps: The polyurethane film is obtained by mixing diisocyanate, polyol, chain extender, catalyst, functional additive, special adhesive material and cross-linking agent, and then subjecting the mixture to melt extrusion and casting treatment.

9. The method for preparing the polyurethane film according to claim 8, characterized in that: The temperature of the melt extrusion is 160-220°C; Preferably, the melt extrusion pressure is 10-25 MPa; Preferably, the melt extrusion is carried out in a twin-screw extruder; Preferably, the speed of the twin-screw extruder is 15-110 rpm; Preferably, the casting process further includes a cooling and molding step; Preferably, the cooling forming method includes using a cooling roller for cooling forming; Preferably, the cooling molding temperature is 10-45°C.

10. Use of the polyurethane film according to any one of claims 1 to 7 in luggage, footwear, packaging, textiles, electronics, automobiles or medical equipment.

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