Anti-aging polyurethane sealant and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, and discloses an anti-aging polyurethane sealant and a preparation method thereof.The polyurethane sealant is prepared by the steps that polyether polyol and binary isocyanate serve as raw materials and react under the action of a catalyst to form a polyurethane prepolymer, then a functional chain extender is used for conducting chain extension on the prepolymer to form polyurethane latex, and then the polyurethane latex is subjected to heat preservation to form the anti-aging polyurethane sealant. The structure of the functional chain extender contains a hindered phenol antioxidant group, and the hindered phenol antioxidant group is introduced into a polyurethane molecular chain by adopting a chemical grafting mode, so that the aging resistance of the polyurethane sealant can be effectively improved, the aging resistance durability of the polyurethane sealant is guaranteed, and the service life of the polyurethane sealant is prolonged. Therefore, the service life and the application value of the polyurethane sealant are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to an anti-aging polyurethane sealant and a preparation method thereof. BACKGROUND

[0002] Polyurethane sealant is a high-quality, multi-purpose adhesive and sealing material, with weather resistance, environmental protection, corrosion resistance and many other advantages, and has been widely used in building, automobile, electronics, aerospace and other fields. In the field of construction, polyurethane sealant is used for sealing of doors and windows, curtain walls, waterproof engineering, etc.; in the field of automobiles, polyurethane sealant is used for vehicle body sealing, shock absorption and noise reduction, etc.; in the field of electronics, polyurethane sealant is used for packaging of electronic components, waterproof sealing of circuit boards, etc.; in the field of aerospace, polyurethane sealant is used for sealing of high temperature and high pressure parts of aircraft, rockets, etc.

[0003] Research has found that polyurethane sealant will age in an environment with high temperature and oxygen, which not only leads to a decrease in bonding performance and makes it difficult to achieve good sealing effect, but also causes yellowing phenomenon that greatly affects the appearance, which makes the service life of polyurethane sealant shorter in relatively harsh environment, so there is still a big defect in practical application.

[0004] Using an antioxidant to modify polyurethane sealant is a common way to improve the anti-aging performance of polyurethane sealant. For example, the patent application No. CN201611236624.9 discloses a two-component polyurethane sealant and a preparation method thereof, which uses the addition of an antioxidant to make the prepared polyurethane sealant have good aging resistance. However, the addition of small molecule antioxidants has the problem of easy precipitation, which makes it difficult to guarantee the long-term anti-aging performance of polyurethane sealant, so this method needs to be improved. SUMMARY

[0005] (I) Technical problems to be solved In view of the shortcomings of the prior art, the present application provides an anti-aging polyurethane sealant and a preparation method thereof, which solves the problem of poor aging resistance of polyurethane sealant.

[0006] (II) Technical solutions A preparation method of an anti-aging polyurethane sealant, comprising the following steps: Step 1, preparation of polyurethane prepolymer After vacuum dehydration of polyether polyol and diisocyanate, pour into the reaction kettle, protect by passing nitrogen, start heating, raise the temperature to 60-65℃, keep for 1-2h, put the catalyst into the reaction kettle, continue to react for 2-4h, form the polyurethane prepolymer; Step 2, preparation of polyurethane latex Put the functionalized chain extender into the reaction kettle, mix with the polyurethane prepolymer, raise the temperature to 70-80℃, keep the temperature, monitor the isocyanate group content in the system in real time, stop heating when no isocyanate group is detected, remove the nitrogen, form the polyurethane latex; Third step: Put the filler into the reaction kettle, mix with the polyurethane latex at a stirring speed of 300-500r / min for 1-3h, discharge, and the polyurethane sealant is formed.

[0007] Preferably, the polyether polyol includes the following raw materials by weight: polyether polyol 60-85 parts, diisocyanate 30-50 parts, catalyst 0.1-0.5 parts, functionalized chain extender 2-6 parts, and filler 15-25 parts.

[0008] Preferably, the polyether polyol is any one of polyether diol or polyether triol.

[0009] Preferably, the diisocyanate is any one of toluene-2,4-diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, or isophorone diisocyanate.

[0010] Preferably, the catalyst is any one of stannous octoate, dibutyltin dilaurate, or dibutyltin diacetate.

[0011] Preferably, the functionalized chain extender is prepared by the following method: Put nitrogen into the reaction kettle to remove the air in the reaction kettle, and then add diethanolamine and toluene into the reaction kettle in turn under the protection of nitrogen, start stirring, mix uniformly, then add 4-bromo-2,6-di-tert-butyl phenol, start heating, raise the temperature in the reaction kettle to 70-80℃, keep the temperature for 4-6h, then stop heating, remove the nitrogen, naturally cool to room temperature, separate the product, and purify to obtain the functionalized chain extender.

[0012] Preferably, the molar ratio of diethanolamine to 4-bromo-2,6-di-tert-butyl phenol is 1:1.

[0013] In the above technical solution, the possible mechanism is that the active secondary amine group in the diethanolamine structure can undergo substitution reaction with the halogen substituent in the structure of 4-bromo-2,6-di-tert-butyl phenol to prepare a functionalized chain extender containing two equivalents of hydroxyl and hindered phenolic antioxidant groups in the structure.

[0014] Preferably, the filler is any one of nano calcium carbonate, carbon black, titanium dioxide, or fumed white carbon black.

[0015] An anti-aging polyurethane sealant is prepared by the above method.

[0016] (Three) beneficial technical effects The application introduces the hindered phenolic antioxidant groups into the polyurethane molecular chain in a chemical connection mode, on the one hand, the heat-oxidation aging resistance effect of the hindered phenolic antioxidant groups is utilized to improve the aging resistance of the polyurethane sealant, on the other hand, the chemical connection mode can firmly fix the antioxidant in the polyurethane sealant, so that the antioxidant is difficult to volatilize and migrate, thus the long-term aging resistance of the polyurethane sealant can be ensured, and the service life and application value of the polyurethane sealant are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0018] Figure 1 The FT-IR diagram of the functionalized chain extender. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the application, the following will be a more comprehensive description of the application. The following gives the preferred embodiments of the application. However, the application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the application more thorough and comprehensive.

[0020] The functionalized chain extender used in the following embodiments is prepared by the following method: Nitrogen is introduced into the reaction kettle to remove air in the reaction kettle, 1.5 mol of diethanolamine and toluene are sequentially added to the reaction kettle under the protection of nitrogen, stirring is started, after mixing uniformly, 1.5 mol of 4-bromo-2, 6-di-tert-butyl phenol is added and mixed, heating is started, the temperature in the reaction kettle is increased to 75℃, and after 6h of incubation, heating is stopped, nitrogen is removed, and the product is separated after natural cooling to room temperature, and the functionalized chain extender can be obtained after purification treatment.

[0021] Analysis shows that 3404cm -1 is the characteristic absorption peak of hydroxyl group, 3000~3100cm -1 is the characteristic absorption peak of C-H on benzene ring, 1413cm -1 is the characteristic absorption peak of C-N.

[0022] Example 1 A method for making an anti-aging polyurethane sealant, comprising the following steps: Step 1, preparing a polyurethane prepolymer After vacuum dehydration of 60 parts of polyether triol and 30 parts of toluene-2,4-diisocyanate, pour them into a reaction kettle, protect by introducing nitrogen, start heating, raise the temperature to 60℃, and keep for 1h, then put 0.1 parts of dibutyltin dilaurate into the reaction kettle, continue to react for 2h to form a polyurethane prepolymer, wherein the molecular weight of the polyether triol is 3000; Step 2, preparing a polyurethane latex Put 2 parts of a functionalized chain extender into the reaction kettle, mix with the polyurethane prepolymer, raise the temperature to 7℃, keep the reaction, monitor the isocyanate group content in the system in real time, stop heating when no isocyanate group is detected, remove the nitrogen, and form a polyurethane latex; Step 3: Put 15 parts of nano calcium carbonate into the reaction kettle, mix with the polyurethane latex at a stirring speed of 300r / min for 1h, discharge, and form a polyurethane sealant.

[0023] Example 2 A method for making an anti-aging polyurethane sealant, comprising the following steps: Step 1, preparing a polyurethane prepolymer After vacuum dehydration of 65 parts of polyether triol and 45 parts of toluene-2,4-diisocyanate, pour them into a reaction kettle, protect by introducing nitrogen, start heating, raise the temperature to 65℃, and keep for 2h, then put 0.2 parts of dibutyltin dilaurate into the reaction kettle, continue to react for 3h to form a polyurethane prepolymer, wherein the molecular weight of the polyether triol is 3000; Step 2, preparing a polyurethane latex Put 5 parts of a functionalized chain extender into the reaction kettle, mix with the polyurethane prepolymer, raise the temperature to 75℃, keep the reaction, monitor the isocyanate group content in the system in real time, stop heating when no isocyanate group is detected, remove the nitrogen, and form a polyurethane latex; Step 3: Put 18 parts of nano calcium carbonate into the reaction kettle, mix with the polyurethane latex at a stirring speed of 500r / min for 2h, discharge, and form a polyurethane sealant.

[0024] Example 3 A method for making an anti-aging polyurethane sealant, comprising the following steps: Step 1, preparing a polyurethane prepolymer Put 85 parts of polyether triols, 50 parts of toluene-2, 4-diisocyanate ester into the reaction kettle after vacuum dehydration, protect by introducing nitrogen, start heating, raise the temperature to 65℃, keep for 2h, put 0.5 parts of dibutyltin dilaurate into the reaction kettle, continue to react for 4h to form polyurethane prepolymer, wherein the molecular weight of the polyether triols is 3000; Second step, preparation of polyurethane latex Put 6 parts of functionalized chain extender into the reaction kettle, mix with the polyurethane prepolymer, raise the temperature to 80℃, keep for reaction, monitor the isocyanate group content in the system in real time, stop heating when no isocyanate group is monitored, remove nitrogen to form polyurethane latex; Third step: Put 25 parts of nano calcium carbonate into the reaction kettle, mix with the polyurethane latex under the stirring speed of 500r / min for 3h, discharge, and the polyurethane sealant is formed.

[0025] Comparative example 1 A method for making an anti-aging polyurethane sealant, comprising the following steps: First step, preparation of polyurethane prepolymer Put 65 parts of polyether triols, 45 parts of toluene-2, 4-diisocyanate ester into the reaction kettle after vacuum dehydration, protect by introducing nitrogen, start heating, raise the temperature to 65℃, keep for 2h, put 0.2 parts of dibutyltin dilaurate into the reaction kettle, continue to react for 3h to form polyurethane prepolymer, wherein the molecular weight of the polyether triols is 3000; Second step, preparation of polyurethane latex Put 5 parts of 1, 4-butanediol into the reaction kettle, mix with the polyurethane prepolymer, raise the temperature to 75℃, keep for reaction, monitor the isocyanate group content in the system in real time, stop heating when no isocyanate group is monitored, remove nitrogen to form polyurethane latex; Third step: Put 18 parts of nano calcium carbonate into the reaction kettle, mix with the polyurethane latex under the stirring speed of 500r / min for 2h, discharge, and the polyurethane sealant is formed.

[0026] According to the national standard GB / T 532-2008, the polyurethane sealant prepared in example 1- example 3 and comparative example 1 of the application is tested for 180° peeling strength; after the test is completed, the polyurethane sealant is placed in an oven at 80℃ for 24h, taken out after the accelerated aging experiment, and tested for 180° peeling strength again; The test results are as follows:

[0027] It can be known from the analysis of the test results that the peeling strength reduction value of the polyurethane sealant prepared by the embodiment 1 to the embodiment 3 before and after the accelerated aging treatment is limited, which represents good aging resistance, and the comparative example adopts the conventional 1,4-butanediol as a chain extender, and the peeling strength is obviously reduced after the accelerated aging experiment, and the good sealing effect can not be achieved.

[0028] According to the ideal embodiments of the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. A method of making an anti-aging polyurethane sealant, characterized by, The method comprises the following steps: The first step is to prepare a polyurethane prepolymer After vacuum dehydration of the polyether polyol and the diisocyanate, the mixture is poured into a reaction kettle, nitrogen is introduced for protection, heating is started, the temperature is raised to 60-65 DEG C, and the mixture is kept for 1-2 hours, the catalyst is put into the reaction kettle, and the reaction is continued for 2-4 hours to form the polyurethane prepolymer; The second step is to prepare a polyurethane latex The functionalized chain extender is put into the reaction kettle and mixed with the polyurethane prepolymer, the temperature is raised to 70-80 DEG C, and the mixture is kept for reaction, the content of isocyanate groups in the system is monitored in real time, and when no isocyanate group is detected, the heating is stopped, the nitrogen is removed, and the polyurethane latex is formed; The third step is to put the filler into the reaction kettle, mix the polyurethane latex at a stirring speed of 300-500 r / min for 1-3 hours, and discharge the mixture to form the polyurethane sealant.

2. The method of claim 1, wherein the anti-aging polyurethane sealant is prepared by mixing the polyol, the polyisocyanate, the anti-aging agent, and the catalyst. The polyether polyol comprises the following raw materials by weight: 60-85 parts of polyether polyol, 30-50 parts of diisocyanate, 0.1-0.5 parts of catalyst, 2-6 parts of functionalized chain extender, and 15-25 parts of filler.

3. The method of claim 1 or 2, wherein the anti-aging polyurethane sealant is prepared by adding the anti-aging agent to the polyurethane sealant composition. The polyether polyol is any one of polyether diol or polyether triol.

4. The method of claim 1-2, wherein the anti-aging polyurethane sealant is prepared by adding the anti-aging agent to the polyurethane sealant. The diisocyanate is any one of toluene-2, 4-diisocyanate, diphenyl methane diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate.

5. The method of claim 1-2, wherein the anti-aging polyurethane sealant is prepared by adding the following components to a polyurethane sealant composition: 0.1-0.5 parts by weight of the compound of Formula (I) or (II) based on 100 parts by weight of the polyurethane sealant composition. The catalyst is any one of stannous octoate, dibutyl tin dilaurate or dibutyl tin diacetate.

6. A method for preparing an anti-aging polyurethane sealant according to any one of claims 1-2, characterized in that, The functionalized chain extender is prepared by the following method: Nitrogen is introduced into the reaction kettle to remove air in the reaction kettle, diethanolamine and toluene are sequentially added to the reaction kettle under nitrogen protection, stirring is started, the mixture is uniformly mixed, 4-bromo-2, 6-di-tert-butyl phenol is added and mixed, heating is started, the temperature in the reaction kettle is raised to 70-80 DEG C, the mixture is kept for reaction for 4-6 hours, the heating is stopped, the nitrogen is removed, the mixture is naturally cooled to room temperature, the product is separated, and the functionalized chain extender is obtained after purification treatment.

7. The method of claim 6, wherein the anti-aging polyurethane sealant is prepared by adding the anti-aging agent to the polyurethane sealant. The molar ratio of diethanolamine to 4-bromo-2, 6-di-tert-butyl phenol is 1:

1.

8. A method for preparing an anti-aging polyurethane sealant according to any one of claims 1-2, characterized in that, The filler is any one of nano calcium carbonate, carbon black, titanium dioxide or fumed white carbon black.

9. An anti-aging polyurethane sealant, characterized by, The method is prepared by the method of claim 1.

Images