Polyurethane adhesive as well as preparation method and use method thereof

Abstract

The invention relates to the technical field of adhesives, and provides a polyurethane adhesive and a preparation method and a use method thereof.The polyurethane adhesive comprises a first component and a second component, the first component is prepared from a polyurethane prepolymer, isocyanate, pigment filler and a thixotropic agent; the second component is prepared from the following raw materials: polyol, a water removal agent, a pigment filler, a first catalyst and a second catalyst; the polyurethane prepolymer is obtained through reaction of a low-activity isocyanate monomer and a chain extender, the low-activity isocyanate monomer is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and a hexamethylene diisocyanate tripolymer, and the chain extender is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate tripolymer. The first catalyst is selected from at least one of an organic tin catalyst and an organic bismuth catalyst, and the second catalyst is selected from at least one of amine catalysts.

Description

Technical Field

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

[0002] Polyurethane adhesives are high-strength, abrasion-resistant, chemical-resistant, and flexible adhesives. Made from polyurethane polymers, their molecular chains contain a large number of urethane and isocyanate groups, resulting in excellent shear strength and impact resistance, along with superior rubber properties, making them suitable for a variety of structural bonding applications.

[0003] Currently, all polyurethane adhesives can be cured at room temperature, but the curing time is relatively long. With the development of industry and advancement of technology, production efficiency has been further improved, and there is an urgent need for a polyurethane adhesive that can cure quickly. However, the rapid curing of polyurethane adhesives is often accompanied by a significant shortening of the open time and a decrease in the shear strength of the product. Therefore, there is an urgent need to develop a polyurethane adhesive with a controllable open time, rapid curing at room temperature, and good shear strength. Summary of the Invention

[0004] The purpose of this application is to provide a polyurethane adhesive and its preparation and use methods, which, while ensuring the shear strength of the polyurethane adhesive, solve the problems of polyurethane adhesives such as difficult to control the dry time and long time to develop initial strength at room temperature, thereby improving production efficiency and reducing energy consumption. The specific technical solution is as follows:

[0005] The first aspect of the present application provides a polyurethane adhesive comprising a first component and a second component; wherein, by weight, the raw materials of the first component include: 20-50 parts of a polyurethane prepolymer, 10-30 parts of an isocyanate, 30-50 parts of a pigment or filler, and 0.5-1 part of a thixotropic agent; and the raw materials of the second component include: 30-60 parts of a polyol, 3-10 parts of a water scavenger, 30-50 parts of a pigment or filler, 2-5 parts of a first catalyst, and 0.5-3 parts of a second catalyst. The polyurethane prepolymer is obtained by reacting a low-activity isocyanate monomer and a chain extender, wherein the low-activity isocyanate monomer is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate trimer; the first catalyst is selected from at least one of an organotin catalyst and an organobismuth catalyst; and the second catalyst is selected from at least one of an amine catalyst.

[0006] In some embodiments of the present application, the low-reactivity isocyanate monomer is selected from hexamethylene diisocyanate trimer.

[0007] In some embodiments of the present application, the first catalyst is selected from at least one of dibutyltin di(dodecylsulfide), dibutyltin mercaptan, dimethyltin dimercaptoacetate, bismuth tricarboxylate, dibutyltin dilaurate, stannous octoate, bismuth isooctanoate, bismuth cyclohexaneate and bismuth laurate; and the second catalyst is selected from at least one of N,N-dimethyl(4-methyl-1-piperazinyl)ethylamine, 1,8-diazabicycloundec-7-ene, triethylamine, bismorpholinodiethyl ether, N-(dimethylaminopropyl)diisopropanolamine and N,N-dimethylbenzylamine.

[0008] In some embodiments of the present application, the weight content of isocyanate groups in the polyurethane prepolymer is between 3 wt % and 10 wt %.

[0009] In some embodiments of the present application, the chain extender is selected from at least one of castor oil-modified polyol, dimer acid-modified polyester polyol, 1,4-butanediol, 1,6-hexanediol, triethanolamine and glycerol, the castor oil-modified polyol has a relative molecular weight of 420-580, and a hydroxyl value of 160-200 mgKOH / g; the dimer acid-modified polyester polyol has a relative molecular weight of 1800-2100, and a hydroxyl value of 50-58 mgKOH / g.

[0010] In some embodiments of the present application, the isocyanate is selected from at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, polymethylene polyphenyl isocyanate and hexamethylene diisocyanate trimer.

[0011] In some embodiments of the present application, the pigment and filler is selected from at least one of wollastonite, alumina, aluminum hydroxide, zinc oxide, talc, mica powder, silica powder and calcium carbonate.

[0012] In some embodiments of the present application, the thixotropic agent is selected from at least one of fumed silica, polyamide wax, and organic bentonite.

[0013] In some embodiments of the present application, the polyol is selected from at least one of polyoxypropylene polyol, polytetramethylene glycol polyol, bisphenol A modified polyether polyol, castor oil modified polyol, and dimer acid modified polyester polyol. The polyoxypropylene polyol has a relative molecular weight of 400-2000 and a hydroxyl value of 56-280 mgKOH / g; the polytetramethylene glycol polyol has a relative molecular weight of 1000-4000 and a hydroxyl value of 28-120 mgKOH / g; the bisphenol A modified polyether polyol has a relative molecular weight of 360-480 and a hydroxyl value of 260-300 mgKOH / g; the castor oil modified polyol has a relative molecular weight of 420-580 and a hydroxyl value of 160-200 mgKOH / g; and the dimer acid modified polyester polyol has a relative molecular weight of 1800-2100 and a hydroxyl value of 50-58 mgKOH / g.

[0014] In some embodiments of the present application, the water removal agent is selected from 3A type molecular sieve.

[0015] The second aspect of the present application provides a method for preparing the polyurethane adhesive described in the first aspect of the present application, comprising:

[0016] Adding the low-activity isocyanate monomer and the chain extender into a reactor, wherein the weight ratio of the low-activity isocyanate monomer to the chain extender is 100:(31-213), stirring evenly, heating the reactor to 45-80° C., reacting for 4-12 hours, and obtaining a polyurethane prepolymer having an isocyanate group weight content of 3wt%-10wt%;

[0017] 20-50 parts of the polyurethane prepolymer, 10-30 parts of isocyanate, 30-50 parts of pigment and filler, and 0.5-1 part of thixotropic agent are uniformly mixed and degassed in a vacuum stirring kettle to obtain the first component;

[0018] The second component is obtained by uniformly mixing 30-60 parts of the polyol, 3-10 parts of the water scavenger, 30-50 parts of the pigment and filler, 2-5 parts of the first catalyst and 0.5-3 parts of the second catalyst, and degassing the mixture in a vacuum stirring kettle.

[0019] The third aspect of the present application provides a method for using the polyurethane adhesive described in the first aspect of the present application or the polyurethane adhesive prepared in the second aspect of the present application, wherein the first component and the second component are uniformly mixed in a mass ratio of 1.0:(0.8~1.2) and used.

[0020] Beneficial effects of this application:

[0021] The present application provides a polyurethane adhesive and its preparation and use methods, comprising a first component and a second component. The first component comprises, by weight, 20-50 parts of a polyurethane prepolymer, 10-30 parts of an isocyanate, 30-50 parts of a pigment or filler, and 0.5-1 part of a thixotropic agent. The second component comprises 30-60 parts of a polyol, 3-10 parts of a water scavenger, 30-50 parts of a pigment or filler, 2-5 parts of a first catalyst, and 0.5-3 parts of a second catalyst. The polyurethane prepolymer is obtained by reacting a low-activity isocyanate monomer and a chain extender, the low-activity isocyanate monomer being selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate trimer. The first catalyst is selected from at least one of an organotin catalyst and an organobismuth catalyst. The second catalyst is selected from at least one of an amine catalyst. The polyurethane prepolymer in this application is obtained by reacting a low-reactivity isocyanate monomer and a chain extender, and has the characteristics of low reactive group content and low reactivity; the first catalyst is an organic metal catalyst, and compared with the second catalyst, an amine catalyst, the first catalyst also has a strong catalytic effect on the low-reactivity polyurethane prepolymer; this application uses the synergistic effect of the low-reactivity prepolymer and the first catalyst with a strong catalytic effect to make the polyurethane adhesive exhibit a controllable curing effect that is slow at first and then fast, that is, it has a longer surface dry time and a shorter initial cure time, and its surface dry time can be adjusted by the type and amount of the first catalyst. Since the content of reactive isocyanate groups in the polyurethane prepolymer is low, it can quickly form a cross-linked network after reacting with the polyol, which is beneficial for the polyurethane adhesive to obtain a high initial bonding strength faster and shorten the initial cure time. In this application, the use of a first catalyst can regulate the tack-free time of the polyurethane adhesive, and the use of a large amount of a second catalyst can accelerate the initial setting speed of the polyurethane adhesive and shorten the initial setting time. The second catalyst is used in conjunction with the first catalyst to adjust the reaction balance during the polyurethane curing process, so that the polyurethane adhesive can fully cure at room temperature after initial curing, ultimately having excellent mechanical properties and adhesive properties. The polyurethane adhesive prepared by the above-mentioned setting has a tack-free time that can be controlled within 30 seconds to 10 minutes, an initial setting time that can be controlled within 4 minutes to 30 minutes, and a shear strength greater than 11 MPa, thereby improving production efficiency and reducing energy consumption.

[0022] Of course, it is not necessary to achieve all the advantages described above at the same time when implementing any product or method of the present application. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in this application. Obviously, the embodiments described are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0024] The present application provides a polyurethane adhesive comprising a first component and a second component. The first component comprises, by weight, 20-50 parts of a polyurethane prepolymer, 10-30 parts of an isocyanate, 30-50 parts of a pigment or filler, and 0.5-1 part of a thixotropic agent. The second component comprises 30-60 parts of a polyol, 3-10 parts of a water scavenger, 30-50 parts of a pigment or filler, 2-5 parts of a first catalyst, and 0.5-3 parts of a second catalyst. The polyurethane prepolymer is obtained by reacting a low-activity isocyanate monomer and a chain extender, the low-activity isocyanate monomer being selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate trimer. The first catalyst is selected from at least one of an organotin catalyst and an organobismuth catalyst. The second catalyst is selected from at least one of an amine catalyst.

[0025] In some embodiments of the present application, the first catalyst is selected from at least one of dibutyltin di(dodecylsulfide), dibutyltin mercaptan, dimethyltin dimercaptoacetate, bismuth tricarboxylate, dibutyltin dilaurate, stannous octoate, bismuth isooctanoate, bismuth cyclohexaneate and bismuth laurate; and the second catalyst is selected from at least one of N,N-dimethyl(4-methyl-1-piperazinyl)ethylamine, 1,8-diazabicycloundec-7-ene, triethylamine, bismorpholinodiethyl ether, N-(dimethylaminopropyl)diisopropanolamine and N,N-dimethylbenzylamine.

[0026] Cure time and adhesion performance are important parameters for evaluating the performance of polyurethane adhesives. However, rapid curing of polyurethane adhesives often results in significant internal stress and insufficient substrate wetting, leading to reduced mechanical and adhesion properties. The inventors have discovered that the polyurethane adhesive of the present application utilizes a low-reactivity isocyanate monomer and a chain extender in the first component to form a polyurethane prepolymer. Compared to highly reactive aromatic isocyanate monomers, the polyurethane prepolymer prepared using low-reactivity aliphatic isocyanate monomers can achieve a controlled reaction rate under the strong catalytic effect of a large amount of the first catalyst. This allows for a controlled dry-to-free time of the polyurethane adhesive, facilitating its application and operation. This also prolongs the wetting of the substrate, resulting in higher shear strength and improved adhesion. For example, when the first catalyst is dibutyltin mercaptan and is used in an amount of 5 parts, the polyurethane adhesive has a dry-to-free time of 3 minutes and 25 seconds; when the first catalyst is bismuth tricarboxylate and is used in an amount of 2 parts, the polyurethane adhesive has a dry-to-free time of 10 minutes. At the same time, prepolymerizing the low-activity isocyanate monomer with the chain extender in advance can reduce the isocyanate group concentration in the polyurethane prepolymer, allowing it to react quickly to form a cross-linked network during the curing process, which is beneficial for the polyurethane adhesive to obtain a high initial bonding strength faster and shorten the initial curing time. In addition, the present application uses a large amount of amine catalyst as a second catalyst to accelerate the initial curing speed of the polyurethane adhesive and shorten the initial curing time. Moreover, when used in conjunction with the first catalyst, it can adjust the reaction balance during the polyurethane curing process, so that the polyurethane adhesive can fully cure at room temperature after initial curing, which is beneficial for improving the shear strength of the polyurethane adhesive. By using the first component and the second component described in the present application simultaneously in the polyurethane adhesive, and controlling the weight fractions of each substance in the first component and the second component within the scope of the present application, the tack-free time of the polyurethane adhesive can be controlled to 30s to 10min and the initial curing time to 4min to 30min, thereby achieving a curing effect of slow curing at the beginning and fast curing at the end, and the shear strength is greater than 11Mpa, which is beneficial for the construction operation of the polyurethane adhesive, thereby improving production efficiency and reducing energy consumption.

[0027] In some embodiments of the present application, the low-reactivity isocyanate monomer is selected from hexamethylene diisocyanate trimer. Selecting the hexamethylene diisocyanate trimer as the low-reactivity isocyanate monomer allows for rapid reaction to form a cross-linked network during the curing process, thereby facilitating faster achievement of high initial bond strength for the polyurethane adhesive and further shortening the initial setting time.

[0028] In the present application, in parts by weight, the polyurethane prepolymer in the first component can be 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts or a range consisting of any two of the values; the isocyanate in the first component can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts or a range consisting of any two of the values; the pigment and filler in the first component can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts or a range consisting of any two of the values; the thixotropic agent in the first component can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part or a range consisting of any two of the values; the polyol in the second component can be The amount of the first catalyst in the second component can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts or a range consisting of any two of the numerical values therein; the amount of the second catalyst in the second component can be 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 ... By preparing the polyurethane adhesive according to the ratio of the present application, the surface drying time of the polyurethane adhesive can be controlled within 30s to 10min and the initial setting time can be controlled within 4min to 30min while ensuring the shear strength, so as to improve production efficiency and reduce energy consumption.

[0029] In some embodiments of the present application, the weight content of isocyanate groups in the polyurethane prepolymer is between 3 wt% and 10 wt%. For example, the weight content of isocyanate groups in the polyurethane prepolymer can be 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10%, or a range consisting of any two of these values. The weight content of isocyanate groups is regulated by controlling the weight ratio of the low-reactivity isocyanate monomer to the chain extender. By controlling the weight content of isocyanate groups in the polyurethane prepolymer within the above range, it is helpful to more quickly obtain a higher bonding strength after the polyurethane adhesive is initially cured, thereby achieving a fast-setting bonding effect.

[0030] In some embodiments of the present application, the chain extender is selected from at least one of castor oil-modified polyol, dimer acid-modified polyester polyol, 1,4-butanediol, 1,6-hexanediol, triethanolamine, and glycerol. The castor oil-modified polyol has a relative molecular weight of 420-580 and a hydroxyl value of 160-200 mgKOH / g; the dimer acid-modified polyester polyol has a relative molecular weight of 1800-2100 and a hydroxyl value of 50-58 mgKOH / g.

[0031] In some embodiments of the present application, the isocyanate is selected from at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, polymethylene polyphenyl isocyanate, and hexamethylene diisocyanate trimer. The isocyanate is selected within the scope of the present application to adjust the viscosity of the first component and improve the operability of the polyurethane adhesive.

[0032] In some embodiments of the present application, the pigment and filler is selected from at least one of wollastonite, alumina, aluminum hydroxide, zinc oxide, talc, mica powder, silica powder and calcium carbonate.

[0033] In some embodiments of the present application, the thixotropic agent is selected from at least one of fumed silica, polyamide wax, and organic bentonite.

[0034] In some embodiments of the present application, the polyol is selected from at least one of polyoxypropylene polyol, polytetramethylene glycol polyol, bisphenol A modified polyether polyol, castor oil modified polyol, and dimer acid modified polyester polyol. The polyoxypropylene polyol has a relative molecular weight of 400-2000 and a hydroxyl value of 56-280 mgKOH / g; the polytetramethylene glycol polyol has a relative molecular weight of 1000-4000 and a hydroxyl value of 28-120 mgKOH / g; the bisphenol A modified polyether polyol has a relative molecular weight of 360-480 and a hydroxyl value of 260-300 mgKOH / g; the castor oil modified polyol has a relative molecular weight of 420-580 and a hydroxyl value of 160-200 mgKOH / g; and the dimer acid modified polyester polyol has a relative molecular weight of 1800-2100 and a hydroxyl value of 50-58 mgKOH / g. In some embodiments of the present application, the water removal agent is selected from 3A type molecular sieve.

[0035] In the present application, there is no particular limitation on the sources of the raw materials used in the first component and the second component, as long as the purpose of the present application can be achieved. For example, the raw materials used in the first component and the second component can be obtained by commercial purchase or by preparation.

[0036] The second aspect of the present application provides a method for preparing the polyurethane adhesive described in the first aspect of the present application, comprising:

[0037] The low-activity isocyanate monomer and the chain extender are added to a reactor, wherein the weight ratio of the low-activity isocyanate monomer to the chain extender is 100:(31-213), and the mixture is stirred evenly. The reactor is heated to 45-80° C. and reacted for 4-12 hours to obtain a polyurethane prepolymer having an isocyanate group weight content of 3wt%-10wt%. The weight ratio of the low-activity isocyanate monomer to the chain extender can be 100:31, 100:57, 100:83, 100:109, 100:135, 100:161, 100:187, 100:213, or a range consisting of any two of these values. The weight ratio of the low-activity isocyanate monomer and the chain extender is within the scope of this application, so that the prepared polyurethane prepolymer has a lower isocyanate group weight content and reactivity, and thus the surface drying time of the polyurethane adhesive described in the first aspect of this application can be controlled between 30s and 10min, the initial setting time can be controlled between 4min and 30min, and it has higher shear strength.

[0038] 20-50 parts of the polyurethane prepolymer, 10-30 parts of isocyanate, 30-50 parts of pigment and filler, and 0.5-1 part of thixotropic agent are uniformly mixed and degassed in a vacuum stirring kettle to obtain the first component;

[0039] The second component is obtained by uniformly mixing 30-60 parts of the polyol, 3-10 parts of the water scavenger, 30-50 parts of the pigment and filler, 2-5 parts of the first catalyst and 0.5-3 parts of the second catalyst, and degassing the mixture in a vacuum stirring kettle.

[0040] The third aspect of the present application provides a method for using the polyurethane adhesive described in the first aspect of the present application or the polyurethane adhesive prepared in the second aspect of the present application, wherein the first component and the second component are uniformly mixed in a mass ratio of 1.0:(0.8-1.2) and used. The mass ratio of the first component to the second component can be 1.0:0.8, 1.0:0.9, 1.0:1.0, 1.0:1.1, 1.0:1.2, or a range consisting of any two of these values.

[0041] Example

[0042] Hereinafter, the embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are by mass.

[0043] Test methods and equipment

[0044] Tests of surface drying time, initial setting time and shear strength:

[0045] Surface drying time: The surface drying time of polyurethane adhesive is tested with reference to the viscosity method in GB / T 7123.1-2015 "Determination of working time of multi-component adhesives", and the adhesive application amount is 20g.

[0046] Initial setting time: The curing time required for the polyurethane adhesive to reach a shear strength of 1 MPa is taken as the initial setting time, and the curing condition is 25°C.

[0047] Shear strength: The shear strength of polyurethane adhesive is tested according to GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)", the curing conditions are 25℃ / 7d, and the substrate is aluminum / aluminum.

[0048] Example 1

[0049] Preparation of polyurethane prepolymer: Isophorone diisocyanate and castor oil-modified polyol were added to a reactor in a weight ratio of 100:175, stirred evenly, and heated to 80°C for 10 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 6 wt%.

[0050] Preparation of the first component: By weight, 25 parts of dicyclohexylmethane diisocyanate, 30 parts of the above-mentioned polyurethane prepolymer, 44 parts of aluminum oxide, and 1 part of fumed silica were mixed uniformly and degassed in a vacuum stirring kettle.

[0051] Preparation of the second component: In parts by weight, 18 parts of castor oil-modified polyol, 15 parts of bisphenol A-modified polyether polyol, 15 parts of polyoxypropylene polyol (Mw=400), 43 parts of aluminum hydroxide, 5 parts of 3A molecular sieve, 3 parts of di(dodecylsulfide)dibutyltin, and 1 part of N,N-dimethyl(4-methyl-1-piperazinyl)ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0052] In the examples of this application, the castor oil-modified polyol is selected from BY-3126 (Beijing Baiyuan Chemical Co., Ltd.), the bisphenol A-modified polyether polyol is selected from 330HP (Arkema, France), the polyoxypropylene polyol is selected from PPG-400 (Nantong Chenrun Chemical Co., Ltd.), and the dimer acid-modified polyester polyol is selected from DA21 (Shanghai Jingri New Materials Technology Co., Ltd.). The polymethylene polyphenyl isocyanate is selected from PM-200 (Wanhua Chemical Group Co., Ltd.), the polytetramethylene furan polyol (Mw = 2000) is selected from PTMG-2000 (Asahikawa Chemical), and the polyoxypropylene polyol (Mw = 1000) is selected from PPG-1000 (Nantong Chenrun Chemical Co., Ltd.). The polyurethane adhesive is used by stirring and uniformly mixing the first and second components in a mass ratio of 1.0:1.1 before use.

[0053] Example 2

[0054] Preparation of polyurethane prepolymer: Hexamethylene diisocyanate and triethanolamine were added to a reactor in a weight ratio of 100:42, stirred evenly, and heated to 45°C for 4 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 10 wt%.

[0055] Preparation of the first component: By weight, 10 parts of hexamethylene diisocyanate trimer, 5 parts of diphenylmethane diisocyanate, 40 parts of the above-mentioned polyurethane prepolymer, 44.5 parts of aluminum oxide, and 0.5 parts of fumed silica were mixed uniformly and degassed in a vacuum stirring kettle.

[0056] Preparation of the second component: By weight, 25 parts of castor oil-modified polyol, 15 parts of bisphenol A-modified polyether polyol, 50 parts of aluminum hydroxide, 4.5 parts of 3A molecular sieve, 5 parts of dibutyl tin mercaptan, and 0.5 parts of triethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0057] How to use polyurethane adhesive: Mix the first component and the second component in a mass ratio of 1.0:1.0 and then use.

[0058] Example 3

[0059] Preparation of the polyurethane prepolymer: Hexamethylene diisocyanate trimer and dimer acid-modified polyester polyol were added to a reactor in a weight ratio of 100:177, stirred evenly, and heated to 60°C for 8 hours to yield a polyurethane prepolymer with an isocyanate group content of 5 wt%. Preparation of the first component: By weight, 4 parts of polymethylene polyphenyl isocyanate, 15 parts of isophorone diisocyanate, 50 parts of the above polyurethane prepolymer, 30 parts of aluminum oxide, and 1 part of fumed silica were mixed evenly and degassed in a vacuum stirred tank. Preparation of the second component: By weight, 40 parts of polytetramethylene glycol (Mw=2000), 20 parts of bisphenol A-modified polyether polyol, 30 parts of silica powder, 4 parts of 3A molecular sieve, 4 parts of dimethyltin dimercaptoacetate, and 2 parts of 1,8-diazabicycloundec-7-ene were mixed evenly and degassed in a vacuum stirred tank.

[0060] How to use polyurethane adhesive: Mix the first component and the second component in a mass ratio of 1.0:1.2 and then use.

[0061] Example 4

[0062] Preparation of polyurethane prepolymer: Hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and 1,4-butanediol were added to a reactor in a weight ratio of 60:40:31, stirred evenly, heated to 45°C and reacted for 4 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 10 wt%.

[0063] Preparation of the first component: By weight, 29 parts of hexamethylene diisocyanate trimer, 20 parts of the above-mentioned polyurethane prepolymer, 50 parts of calcium carbonate, and 1 part of fumed silica were mixed uniformly and degassed in a vacuum stirring kettle.

[0064] Preparation of the second component: In parts by weight, 30 parts of polyoxypropylene polyol (Mw=1000), 24.5 parts of bisphenol A modified polyether polyol, 30 parts of talc, 10 parts of 3A molecular sieve, 2 parts of dimethyltin dimercaptoacetate, 3 parts of dibutyltin mercaptan, and 0.5 parts of N,N-dimethyl (4-methyl-1-piperazinyl) ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0065] How to use polyurethane adhesive: Mix the first component and the second component in a mass ratio of 1.0:1.0 and then use.

[0066] Example 5

[0067] Preparation of polyurethane prepolymer: Isophorone diisocyanate, dimer acid-modified polyester polyol and propylene glycol were added to a reactor in a weight ratio of 100:125:10, stirred evenly, heated to 80°C and reacted for 6 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 8wt%.

[0068] Preparation of the first component: In parts by weight, 5 parts of toluene diisocyanate, 5 parts of dicyclohexylmethane diisocyanate, 44 parts of the above-mentioned polyurethane prepolymer, 45 parts of calcium carbonate, and 1 part of fumed silica were mixed uniformly and degassed in a vacuum stirred kettle.

[0069] Preparation of the second component: In parts by weight, 40 parts of castor oil-modified polyol, 20 parts of dimer acid-modified polyester polyol, 15 parts of aluminum hydroxide, 10 parts of zinc oxide, 10 parts of 3A molecular sieve, 2 parts of bismuth tricarboxylate, and 3 parts of 1,8-diazabicycloundec-7-ene were mixed evenly and degassed in a vacuum stirred tank.

[0070] How to use polyurethane adhesive: Mix the first component and the second component in a mass ratio of 1.0:1.2 and then use.

[0071] Example 6

[0072] Preparation of polyurethane prepolymer: Hexamethylene diisocyanate trimer and castor oil-modified polyol were added to a reactor in a weight ratio of 100:120, stirred evenly, and heated to 80°C for 4 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 3wt%.

[0073] Preparation of the first component: By weight, 30 parts of hexamethylene diisocyanate trimer, 20 parts of the above-mentioned polyurethane prepolymer, 49 parts of aluminum oxide, and 1 part of fumed silica were mixed uniformly and degassed in a vacuum stirred kettle.

[0074] Preparation of the second component: By weight, mix 30 parts castor oil-modified polyol, 25 parts polyoxypropylene polyol (Mw=1000), 35 parts mica powder, 5 parts 3A molecular sieve, 4 parts dibutyltin di(dodecylsulfide), and 1 part 1,8-diazabicycloundec-7-ene. Degas the mixture in a vacuum stirred tank. Usage of the polyurethane adhesive: Mix the first and second components in a mass ratio of 1.0:1.1 and stir until uniformly mixed.

[0075] Example 7

[0076] Preparation of polyurethane prepolymer: Isophorone diisocyanate, 1,4-butanediol and castor oil-modified polyol were added to a reactor in a weight ratio of 100:11:128, stirred evenly, and heated to 60°C for 6 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 5 wt%.

[0077] Preparation of the first component: Based on parts by weight, 10 parts of diphenylmethane diisocyanate, 40 parts of the above-mentioned polyurethane prepolymer, 49 parts of aluminum oxide, and 1 part of fumed silica were mixed evenly and degassed in a vacuum stirred kettle.

[0078] Preparation of the second component: In parts by weight, 8 parts of bisphenol A modified polyether polyol, 15 parts of dimer acid modified polyester polyol, 12 parts of polyoxypropylene polyol (Mw=400), 35 parts of calcium carbonate, 15 parts of silicon powder, 8 parts of 3A molecular sieve, 4 parts of di(dodecylsulfide)dibutyltin, and 3 parts of 1,8-diazabicycloundec-7-ene were mixed uniformly and degassed in a vacuum stirred tank.

[0079] How to use polyurethane adhesive: Mix the first component and the second component in a mass ratio of 1.0:0.8 and then use.

[0080] Example 8

[0081] Preparation of polyurethane prepolymer: Isophorone diisocyanate, hexamethylene diisocyanate and dimer acid-modified polyester polyol were added into a reactor in a weight ratio of 80:20:213, stirred evenly, heated to 80°C and reacted for 12 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 10 wt%.

[0082] Preparation of the first component: By weight, 15 parts of hexamethylene diisocyanate, 40 parts of the above-mentioned polyurethane prepolymer, 44 parts of aluminum oxide, and 1 part of fumed silica were mixed uniformly and degassed in a vacuum stirred kettle.

[0083] Preparation of the second component: In parts by weight, 40 parts of bisphenol A modified polyether polyol, 20 parts of dimer acid modified polyester polyol, 30 parts of aluminum hydroxide, 5 parts of 3A molecular sieve, 3 parts of dibutyl tin mercaptan, and 2 parts of N,N-dimethyl (4-methyl-1-piperazinyl) ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0084] How to use polyurethane adhesive: Mix the first component and the second component in a mass ratio of 1.0:1.1 and then use.

[0085] Example 9

[0086] Preparation of polyurethane prepolymer: Hexamethylene diisocyanate trimer and castor oil-modified polyol were added to a reactor in a weight ratio of 100:80, stirred evenly, and heated to 80°C for 10 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 6 wt%.

[0087] Except that the polyurethane prepolymer in the first component is replaced by the above-mentioned polyurethane prepolymer, the rest is the same as Example 1.

[0088] Comparative Example 1

[0089] The process was the same as that of Example 4 except that the weight portion of talc in the second component was adjusted to 35 parts and dimethyltin dimercaptoacetate and dibutyltin mercaptan were not used.

[0090] Comparative Example 2

[0091] The process was the same as that of Example 4 except that the weight portion of talc in the second component was adjusted to 30.5 parts and N,N-dimethyl(4-methyl-1-piperazinyl)ethanamine was not used.

[0092] Comparative Example 3

[0093] The process is the same as that of Example 4 except that the polyurethane prepolymer is not prepared and used, and the weight proportions of hexamethylene diisocyanate trimer and calcium carbonate in the first component are adjusted to 39 and 60 parts, respectively.

[0094] Comparative Example 4

[0095] Preparation of polyurethane prepolymer: Diphenylmethane diisocyanate and castor oil-modified polyol were added to a reactor in a weight ratio of 100:86, stirred evenly, and heated to 80°C for 4 hours to obtain a polyurethane prepolymer with an isocyanate group weight content of 10 wt%.

[0096] Except that the polyurethane prepolymer in the first component is replaced by the above-mentioned polyurethane prepolymer, the rest is the same as Example 4. Comparative Example 5

[0097] Preparation of the second component: In parts by weight, 30 parts of polyoxypropylene polyol (Mw=1000), 24.5 parts of bisphenol A modified polyether polyol, 33.5 parts of talc, 10 parts of 3A molecular sieve, 0.5 parts of dimethyltin dimercaptoacetate, 1 part of dibutyltin mercaptan, and 0.5 parts of N,N-dimethyl(4-methyl-1-piperazinyl)ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0098] Except for changing the amount of raw materials of the second component, the rest is the same as Example 4.

[0099] Comparative Example 6

[0100] Preparation of the second component: In parts by weight, 30 parts of polyoxypropylene polyol (Mw=1000), 24.5 parts of bisphenol A modified polyether polyol, 28 parts of talc, 10 parts of 3A molecular sieve, 3 parts of dimethyltin dimercaptoacetate, 4 parts of dibutyltin mercaptan, and 0.5 parts of N,N-dimethyl (4-methyl-1-piperazinyl) ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0101] Except for changing the amount of raw materials of the second component, the rest is the same as Example 4.

[0102] Comparative Example 7

[0103] Preparation of the second component: In parts by weight, 30 parts of polyoxypropylene polyol (Mw=1000), 24.5 parts of bisphenol A modified polyether polyol, 30.3 parts of talc, 10 parts of 3A molecular sieve, 2 parts of dimethyltin dimercaptoacetate, 3 parts of dibutyltin mercaptan, and 0.2 parts of N,N-dimethyl (4-methyl-1-piperazinyl) ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0104] Except for changing the amount of raw materials of the second component, the rest is the same as Example 4.

[0105] Comparative Example 8

[0106] Preparation of the second component: In parts by weight, 30 parts of polyoxypropylene polyol (Mw=1000), 24.5 parts of bisphenol A modified polyether polyol, 28 parts of talc, 10 parts of 3A molecular sieve, 2 parts of dimethyltin dimercaptoacetate, 3 parts of dibutyltin mercaptan, and 5 parts of N,N-dimethyl(4-methyl-1-piperazinyl)ethylamine were mixed evenly and degassed in a vacuum stirred kettle.

[0107] Except for changing the amount of raw materials of the second component, the rest is the same as Example 4.

[0108] Table 1 shows the test results of various embodiments and comparative examples.

[0109] Table 1

[0110]

[0111] From Examples 1 to 9 and Comparative Examples 1 to 8, it can be seen that by selecting the first and second components within the scope of this application and regulating the weight proportions of each substance in the first and second components within the scope of this application, the resulting polyurethane adhesive can achieve a tack-free time of 30 seconds to 10 minutes and a setting time of 4 minutes to 30 minutes while maintaining shear strength, thereby improving production efficiency and reducing energy consumption. Comparative Example 1, in which the first catalyst within the scope of this application was not selected in the second component, resulted in a tack-free time of 6 hours and a setting time of more than 1 day, significantly reducing production efficiency and also decreasing shear strength. Comparative Example 2, in which the second catalyst within the scope of this application was not selected in the second component, resulted in a slightly increased tack-free time of 3 minutes to 15 seconds, but a delayed setting time of 16 minutes, and a decreased shear strength after curing. Comparative Example 3, in which no polyurethane prepolymer was prepared in the first component but only an isocyanate monomer was used, resulted in a slightly increased tack-free time, but a significantly increased setting time, and a significantly decreased shear strength. In Comparative Example 4, the first component uses an aromatic isocyanate to synthesize a polyurethane prepolymer, which exhibits significantly higher reactivity than the polyurethane prepolymer synthesized from a low-reactivity isocyanate monomer in Example 4. This results in significantly shortened open-air and initial set times, resulting in a very short workable time. Furthermore, the polyurethane adhesive fails to fully wet the substrate, significantly reducing shear strength. In Comparative Examples 5 and 6, the amount of the first catalyst in the second component raw materials falls outside the range of this application. The shear strength of the resulting polyurethane adhesives is reduced. Furthermore, when the amount of the first catalyst used is below the lower limit of this application, the open-air time is 40 minutes, reducing production efficiency. When the amount of the first catalyst used exceeds the upper limit of this application, the open-air time is less than 15 seconds, which is too short to be workable. In the raw materials of the second component of Comparative Examples 7 and 8, the number of the second catalyst is not within the scope of this application, and the shear strength of the prepared polyurethane adhesives is reduced. Moreover, when the amount of the second catalyst is lower than the lower limit of the range of this application, the initial solidification time is increased, which reduces the production efficiency; when the amount of the second catalyst is higher than the upper limit of the range of this application, although the initial solidification time is slightly shortened, the shear strength decreases significantly.

[0112] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A polyurethane adhesive comprising a first component and a second component; wherein: The raw materials of the first component include, by weight, 20 to 50 parts of polyurethane prepolymer, 10 to 30 parts of isocyanate, 30 to 50 parts of pigment and filler, and 0.5 to 1 part of thixotropic agent; the raw materials of the second component include, by weight, 30 to 60 parts of polyol, 3 to 10 parts of water scavenger, 30 to 50 parts of pigment and filler, 2 to 5 parts of first catalyst, and 0.5 to 3 parts of second catalyst; The polyurethane prepolymer is obtained by reacting a low-activity isocyanate monomer and a chain extender, wherein the low-activity isocyanate monomer is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate trimer; The first catalyst is selected from at least one of an organotin catalyst and an organobismuth catalyst; The second catalyst is selected from at least one amine catalyst.

2. The polyurethane adhesive according to claim 1, wherein The low-activity isocyanate monomer is selected from hexamethylene diisocyanate trimer.

3. The polyurethane adhesive according to claim 1, wherein The weight content of isocyanate groups in the polyurethane prepolymer is between 3wt% and 10wt%.

4. The polyurethane adhesive according to claim 1, wherein The chain extender is selected from at least one of castor oil-modified polyol, dimer acid-modified polyester polyol, 1,4-butanediol, 1,6-hexanediol, triethanolamine and glycerol.

5. The polyurethane adhesive according to claim 1, wherein The isocyanate is selected from at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, polymethylene polyphenyl isocyanate and hexamethylene diisocyanate trimer.

6. The polyurethane adhesive according to claim 1, wherein The pigment and filler is selected from at least one of wollastonite, alumina, aluminum hydroxide, zinc oxide, talc, mica powder, silica powder and calcium carbonate.

7. The polyurethane adhesive according to claim 1, wherein The thixotropic agent is selected from at least one of fumed silica, polyamide wax and organic bentonite.

8. The polyurethane adhesive according to claim 1, wherein The polyol is selected from at least one of polyoxypropylene polyol, polytetramethylene glycol polyol, bisphenol A modified polyether polyol, castor oil modified polyol and dimer acid modified polyester polyol.

9. The polyurethane adhesive according to claim 1, wherein The dehydrating agent is selected from 3A molecular sieve.

10. A method for preparing the polyurethane adhesive according to any one of claims 1 to 9, comprising: Adding the low-activity isocyanate monomer and the chain extender into a reactor, wherein the weight ratio of the low-activity isocyanate monomer to the chain extender is 100:(31-213), stirring evenly, heating the reactor to 45-80° C., reacting for 4-12 hours, and obtaining a polyurethane prepolymer having an isocyanate group weight content of 3wt%-10wt%; 20-50 parts of the polyurethane prepolymer, 10-30 parts of isocyanate, 30-50 parts of pigment and filler, and 0.5-1 part of thixotropic agent are uniformly mixed and degassed in a vacuum stirring kettle to obtain the first component; The second component is obtained by uniformly mixing 30-60 parts of the polyol, 3-10 parts of the water scavenger, 30-50 parts of the pigment and filler, 2-5 parts of the first catalyst and 0.5-3 parts of the second catalyst, and degassing the mixture in a vacuum stirring kettle.

11. A method for using the polyurethane adhesive according to any one of claims 1 to 9 or the polyurethane adhesive prepared by the preparation method according to claim 10, wherein: The first component and the second component are mixed evenly in a mass ratio of 1.0: (0.8-1.2) for use.

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