High-strength waterproof polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a high-strength waterproof polyurethane adhesive and a preparation method thereof, and relates to the technical field of polyurethane adhesives. The invention relates to a flame-retardant polyurethane elastomer, which is prepared from the following ingredients in parts by weight: 40 to 60 parts of polyether polyol, 20 to 30 parts of polyester polyol, 25 to 35 parts of modified diphenylmethane diisocyanate (MDI), 5 to 10 parts of nanometer silicon dioxide, 1 to 3 parts of silane coupling agents, 3 to 5 parts of 1, 4-butanediol (BDO), 0.1 to 0.3 part of dibutyltin dilaurate (catalysts), 0.5 to 1 part of antioxidants and 0.2 to 0.5 part of ultraviolet light absorbers. Through polyether / polyester polyol compounding and MDI reaction, a microphase separation structure is formed, cohesion strength is improved, nano-silica and KH-550 synergistically enhance interface bonding force and inhibit water molecule permeation, the strength retention rate after water resistance is larger than 90%, and the water-resistant polyurethane elastomer is suitable for long-term use in a high-humidity environment.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane adhesives, and specifically relates to a high-strength water-resistant polyurethane adhesive and a preparation method thereof. Background Art

[0002] An adhesive refers to a natural or synthetic, organic or inorganic substance that can connect two or more workpieces or materials together through actions such as interfacial adhesion and cohesion. Adhesives can be classified into thermosetting, hot-melt, room-temperature curing types, etc. according to the application method; into structural, non-structural or special adhesives according to the application object; and into water-soluble, water-emulsion, solvent-based types, etc. according to the form.

[0003] Due to the presence of groups with strong polarity and chemical reactivity in polyurethane adhesives, they have excellent chemical adhesion to substrates containing active hydrogen, such as porous materials like foam, plastic, wood, leather, fabric, paper, ceramics, etc., as well as materials with smooth surfaces like metal, glass, rubber, plastic, etc. Most of the existing polyurethane adhesives are used in the shoe-making industry and the labor protection products industry. The above industries have low requirements for water resistance, so ordinary polyurethane adhesives can meet their requirements. However, for materials in special environments, the bonding strength of existing polyurethane adhesives cannot meet their requirements. For example, inflatable rubber boats, inflatable life jackets and life vests used in sea play projects, due to their special use environment, it is required that the adhesives used for them have better bonding strength and water resistance, so as to ensure that the above play utensils do not leak air during use and guarantee the safety of the passengers.

[0004] Therefore, we propose a high-strength water-resistant polyurethane adhesive and a preparation method thereof to solve the problems raised above.

[0005] The above information disclosed in this background art is only used to increase the understanding of the background art of the present invention. Therefore, it may include prior art that is not known to those of ordinary skill in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-strength water-resistant polyurethane adhesive and a preparation method thereof to solve the problems raised in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A high-strength water-resistant polyurethane adhesive, comprising the following components in parts by weight: 40 - 60 parts of polyether polyol, 20 - 30 parts of polyester polyol, 25 - 35 parts of modified diphenylmethane diisocyanate (MDI), 5 - 10 parts of nano-silica, 1 - 3 parts of silane coupling agent, 3 - 5 parts of 1,4-butanediol (BDO), 0.1 - 0.3 parts of dibutyltin dilaurate (catalyst), 0.5 - 1 part of antioxidant, and 0.2 - 0.5 part of ultraviolet absorber.

[0008] Preferably, the hydroxyl value of the polyether polyol is 56 mg KOH / g, and the hydroxyl value of the polyester polyol is 110 mg KOH / g.

[0009] Preferably, the particle size of the nano-silica is 20 - 30 nm.

[0010] Preferably, the silane coupling agent is KH-550.

[0011] Preferably, the antioxidant is antioxidant 1010.

[0012] Preferably, the ultraviolet absorber is UV-327.

[0013] A preparation method of a high-strength water-resistant polyurethane adhesive, comprising the following steps:

[0014] Step 1. Preparation of prepolymer:

[0015] Step 1.1: Add the polyether polyol and the polyester polyol to a reaction kettle, and dehydrate at 110 - 120 °C and a vacuum degree of -0.095 MPa for 2 hours;

[0016] Step 1.2: Cool down to 60 °C, add modified diphenylmethane diisocyanate, and stir and react at 500 rpm for 3 hours under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0017] Step 1.3: Add nano-silica and a silane coupling agent, and ultrasonically disperse for 30 minutes;

[0018] Step 2. Chain extension reaction:

[0019] Cool down the prepolymer in Step 1.3 to 40 °C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5% - 4.0%;

[0020] Step 3. Auxiliary agent mixing:

[0021] Add an antioxidant and an ultraviolet absorber to the product in Step 2, homogenize for 10 minutes, and discharge and seal for storage.

[0022] Preferably, the curing conditions of the adhesive are: initial curing at 25 °C for 24 hours after coating, and then post-curing at 80 °C for 2 hours.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention forms a microphase separation structure through the reaction of polyether / polyester polyol blending with MDI to enhance the cohesive strength. The interfacial bonding force is synergistically enhanced by nano-silica and KH-550 to inhibit the penetration of water molecules, and the strength retention rate after water resistance is >90%, which is suitable for long-term use in high-humidity environments.

[0025] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the preparation process of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] A high-strength water-resistant polyurethane adhesive comprises the following components in parts by weight:

[0029] Prepolymer component: 40-60 parts of polyether polyol, 20-30 parts of polyester polyol, 25-35 parts of modified diphenylmethane diisocyanate, 5-10 parts of nano-silica, 1-3 parts of silane coupling agent;

[0030] Chain extender component: 3-5 parts of 1,4-butanediol, 0.1-0.3 parts of dibutyltin dilaurate;

[0031] Auxiliary agent: 0.5-1 part of antioxidant, 0.2-0.5 part of ultraviolet absorber.

[0032] Specifically, the polyether polyol has a hydroxyl value of 56 mgKOH / g, the polyester polyol has a hydroxyl value of 110 mgKOH / g; the nano-silica has a particle size of 20-30 nm; the silane coupling agent is KH-550; the antioxidant is antioxidant 1010; the ultraviolet absorber is UV-327.

[0033] A preparation method of a high-strength water-resistant polyurethane adhesive comprises the following steps:

[0034] Step 1, prepolymer preparation:

[0035] Step 1.1: Add polyether polyol and polyester polyol into the reaction kettle, and dehydrate for 2 hours at 110 - 120°C and a vacuum degree of -0.095 MPa;

[0036] Step 1.2: Cool down to 60°C, add modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0037] Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes;

[0038] Step 2. Chain extension reaction:

[0039] Cool down the prepolymer obtained in Step 1.3 to 40°C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5% - 4.0%;

[0040] Step 3. Auxiliary agent mixing:

[0041] Add antioxidant and ultraviolet absorber to the product of Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0042] The curing conditions of the adhesive are: initially cure at 25°C for 24 hours after coating, and then post-cure at 80°C for 2 hours.

[0043] Preparation of modified diphenylmethane diisocyanate: Mix MDI, dibasic acid, polyester polyol and phosphoric acid in a certain proportion and carry out the reaction. The specific weight parts are: 100 parts of MDI, 1 - 10 parts of dibasic acid, 20 - 60 parts of polyester polyol, 0.002 - 0.008 parts of phosphoric acid. The reaction conditions are from room temperature to 100°C. After the reaction is completed, separate the modified diphenylmethane diisocyanate by methods such as distillation and crystallization.

[0044] Example 1

[0045] Prepare the following components in weight parts: 40 parts of polyether polyol (hydroxyl value 56 mgKOH / g), 30 parts of polyester polyol (hydroxyl value 110 mgKOH / g), 30 parts of modified diphenylmethane diisocyanate, 5 parts of nano-silica (particle size 20 - 30 nm), 2 parts of silane coupling agent (KH-550), 4 parts of 1,4-butanediol, 0.15 part of dibutyltin dilaurate, 0.7 part of antioxidant (1010), 0.2 part of ultraviolet absorber (UV-327).

[0046] Step 1. Preparation of prepolymer:

[0047] Step 1.1: Add polyether polyol and polyester polyol into the reaction kettle, and dehydrate for 2 hours at 110 - 120°C and a vacuum degree of -0.095 MPa;

[0048] Step 1.2: Cool down to 60°C, add modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0049] Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes;

[0050] Step 2. Chain extension reaction:

[0051] Cool down the prepolymer obtained in Step 1.3 to 40°C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5%-4.0%;

[0052] Step 3. Auxiliary agent mixing:

[0053] Add antioxidant and ultraviolet absorber to the product of Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0054] The curing conditions of the adhesive are: initial curing at 25°C for 24 hours after coating, and then post-curing at 80°C for 2 hours.

[0055] Example 2

[0056] Prepare the following components in parts by weight: 50 parts of polyether polyol (hydroxyl value 56 mgKOH / g), 25 parts of polyester polyol (hydroxyl value 110 mgKOH / g), 25 parts of modified diphenylmethane diisocyanate, 7 parts of nano-silica (particle size 20-30 nm), 2.5 parts of silane coupling agent (KH-550), 4 parts of 1,4-butanediol, 0.15 part of dibutyltin dilaurate, 0.8 part of antioxidant (1010), and 0.3 part of ultraviolet absorber (UV-327).

[0057] Step 1. Preparation of prepolymer:

[0058] Add polyether polyol and polyester polyol to the reaction kettle, and dehydrate at 110-120°C and a vacuum degree of -0.095 MPa for 2 hours;

[0059] Step 1.2: Cool down to 60°C, add modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0060] Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes;

[0061] Step 2. Chain extension reaction:

[0062] Cool the prepolymer obtained in Step 1.3 to 40°C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5%-4.0%.

[0063] Step 3. Auxiliary agent mixing:

[0064] Add an antioxidant and an ultraviolet absorber to the product of Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0065] The curing conditions of the adhesive are: after coating, initially cure at 25°C for 24 hours, and then post-cure at 80°C for 2 hours.

[0066] Example 3

[0067] Prepare the following components in parts by weight: 55 parts of polyether polyol (hydroxyl value 56 mgKOH / g), 20 parts of polyester polyol (hydroxyl value 110 mgKOH / g), 25 parts of modified diphenylmethane diisocyanate, 8.5 parts of nano-silica (particle size 20-30 nm), 2.5 parts of silane coupling agent (KH-550), 4.5 parts of 1,4-butanediol, 0.2 part of dibutyltin dilaurate, 0.9 part of antioxidant (1010), and 0.4 part of ultraviolet absorber (UV-327).

[0068] Step 1. Preparation of prepolymer:

[0069] Step 1.1: Add the polyether polyol and polyester polyol to the reaction kettle, and dehydrate at 110-120°C and a vacuum of -0.095 MPa for 2 hours;

[0070] Step 1.2: Cool to 60°C, add the modified diphenylmethane diisocyanate, and stir and react at 500 rpm for 3 hours under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0071] Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes;

[0072] Step 2. Chain extension reaction:

[0073] Cool the prepolymer obtained in Step 1.3 to 40°C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5%-4.0%;

[0074] Step 3. Auxiliary agent mixing:

[0075] Add an antioxidant and an ultraviolet absorber to the product of Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0076] The curing conditions of the adhesive are: after coating, initially cure at 25°C for 24 hours, and then post-cure at 80°C for 2 hours.

[0077] Example 4

[0078] Prepare the following components in parts by weight: 60 parts of polyether polyol (hydroxyl value 56 mg KOH / g), 20 parts of polyester polyol (hydroxyl value 110 mg KOH / g), 35 parts of modified diphenylmethane diisocyanate, 10 parts of nano-silica (particle size 20 - 30 nm), 3 parts of silane coupling agent (KH-550), 5 parts of 1,4-butanediol, 0.2 part of dibutyltin dilaurate, 1 part of antioxidant (1010), and 0.5 part of ultraviolet absorber (UV-327).

[0079] Step 1. Preparation of prepolymer:

[0080] Step 1.1: Add the polyether polyol and polyester polyol to the reaction kettle, and dehydrate for 2 hours at 110 - 120 °C and a vacuum degree of -0.095 MPa;

[0081] Step 1.2: Cool down to 60 °C, add the modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0082] Step 1.3: Add the nano-silica and the silane coupling agent, and ultrasonically disperse for 30 minutes;

[0083] Step 2. Chain extension reaction:

[0084] Cool down the prepolymer obtained in Step 1.3 to 40 °C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5% - 4.0%;

[0085] Step 3. Mixing of additives:

[0086] Add the antioxidant and the ultraviolet absorber to the product obtained in Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0087] The curing conditions of the adhesive are: initial curing at 25 °C for 24 hours after coating, and then post-curing at 80 °C for 2 hours.

[0088] Comparative Example 1

[0089] Prepare the following components in parts by weight: 40 parts of polyether polyol (hydroxyl value 56 mg KOH / g), 30 parts of polyester polyol (hydroxyl value 110 mg KOH / g), 30 parts of modified diphenylmethane diisocyanate, 4 parts of 1,4-butanediol, 0.15 part of dibutyltin dilaurate, 0.7 part of antioxidant (1010), and 0.2 part of ultraviolet absorber (UV-327).

[0090] Step 1. Preparation of prepolymer:

[0091] Step 1.1: Add polyether polyol and polyester polyol into the reaction kettle, and dehydrate for 2 hours at 110 - 120 °C and a vacuum degree of -0.095 MPa;

[0092] Step 1.2: Cool down to 60 °C, add modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0093] Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes;

[0094] Step 2. Chain extension reaction:

[0095] Cool down the prepolymer obtained in Step 1.3 to 40 °C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5% - 4.0%;

[0096] Step 3. Auxiliary agent mixing:

[0097] Add antioxidant and ultraviolet absorber to the product obtained in Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0098] The curing conditions of the adhesive are: initial curing at 25 °C for 24 hours after coating, and then post-curing at 80 °C for 2 hours.

[0099] Comparative Example 2

[0100] Prepare the following components in parts by weight: 30 parts of polyether polyol (hydroxyl value 56 mgKOH / g), 30 parts of polyester polyol (hydroxyl value 110 mgKOH / g), 5 parts of nano-silica (particle size 20 - 30 nm), 2 parts of silane coupling agent (KH-550), 4 parts of 1,4-butanediol, 0.15 part of dibutyltin dilaurate, 0.7 part of antioxidant (1010), and 0.2 part of ultraviolet absorber (UV-327).

[0101] Step 1. Preparation of prepolymer:

[0102] Step 1.1: Add polyether polyol and polyester polyol into the reaction kettle, and dehydrate for 2 hours at 110 - 120 °C and a vacuum degree of -0.095 MPa;

[0103] Step 1.2: Cool down to 60 °C, add modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer;

[0104] Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes;

[0105] Step 2. Chain extension reaction:

[0106] Cool the prepolymer in Step 1.3 to 40°C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5%-4.0%.

[0107] Step 3. Auxiliary agent mixing:

[0108] Add an antioxidant and an ultraviolet absorber to the product in Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

[0109] The curing conditions of the adhesive are: initially cure at 25°C for 24 hours after applying the adhesive, and then post-cure at 80°C for 2 hours.

[0110] Performance testing

[0111] Bonding method: Clean the surface to be coated with alcohol, and use the adhesives of Examples 1-4 and Comparative Examples 1-2 respectively. Use a spatula to scrape the adhesive and apply it forcefully on all surfaces to be bonded multiple times to ensure that the adhesive fully covers the bonding surface, and then carry out the subsequent bonding work; after bonding, it is necessary to heat up and cure. First, initially cure at 25°C for 24 hours, and then post-cure at 80°C for 2 hours.

[0112] Bonding strength test: Bond six groups of 5-mm-thick aluminum alloy lap joints using the above method, and refer to ASTM D1002 to test the tensile shear strength of the aluminum alloy lap joints.

[0113] Water resistance performance test: Immerse the cured specimen in water at 50°C for 168 hours, and test the strength retention rate.

[0114] The specific results are as follows:

[0115]

[0116]

[0117] As can be seen from the above, in Comparative Example 1, nano-silica and KH-550 were not added, and its initial strength and strength retention were greatly reduced compared with those of Examples 1-4; in Comparative Example 2, modified diphenylmethane diisocyanate was not added, and its initial strength and strength retention were greatly reduced compared with those of Examples 1-4, and the strength retention was improved compared with that of Comparative Example 1. In summary, the present invention reacts polyether / polyester polyol blends with MDI to form a microphase separation structure, enhancing the cohesive strength. The synergistic effect of nano-silica and KH-550 enhances the interfacial bonding force and inhibits the penetration of water molecules. The strength retention rate after water resistance is >90%, achieving the synergistic improvement of high strength and water resistance, and is suitable for long-term use in high-humidity environments.

[0118] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0119] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-strength water-resistant polyurethane adhesive, characterized in that It comprises components in the following parts by weight: 40 - 60 parts of polyether polyol, 20 - 30 parts of polyester polyol, 25 - 35 parts of modified diphenylmethane diisocyanate, 5 - 10 parts of nano-silica, 1 - 3 parts of silane coupling agent, 3 - 5 parts of 1,4-butanediol, 0.1 - 0.3 parts of dibutyltin dilaurate, 0.5 - 1 part of antioxidant, and 0.2 - 0.5 part of ultraviolet absorber.

2. The high-strength water-resistant polyurethane adhesive according to claim 1, characterized in that: The polyether polyol has a hydroxyl value of 56 mgKOH / g, and the polyester polyol has a hydroxyl value of 110 mgKOH / g.

3. A high-strength water-resistant polyurethane adhesive according to claim 1, characterized in that: The nano-silica has a particle size of 20 - 30 nm.

4. The high-strength water-resistant polyurethane adhesive according to claim 1, wherein: The silane coupling agent is KH-550.

5. The high-strength water-resistant polyurethane adhesive according to claim 1, characterized in that: The antioxidant is antioxidant 1010.

6. The high-strength water-resistant polyurethane adhesive according to claim 1, characterized in that: The ultraviolet absorber is UV-327.

7. The preparation method of a high-strength water-resistant polyurethane adhesive according to any one of claims 1-6, characterized in that, It includes the following steps: Step 1. Preparation of prepolymer: Step 1.1: Add polyether polyol and polyester polyol into a reaction kettle, and dehydrate at 110 - 120 °C and a vacuum degree of -0.095 MPa for 2 hours. Step 1.2: Cool down to 60 °C, add modified diphenylmethane diisocyanate, and stir and react for 3 hours at 500 rpm under nitrogen protection to obtain an isocyanate-terminated prepolymer. Step 1.3: Add nano-silica and silane coupling agent, and ultrasonically disperse for 30 minutes. Step 2. Chain extension reaction: Cool down the prepolymer obtained in Step 1.3 to 40 °C, add 1,4-butanediol and dibutyltin dilaurate, and stir and react for 1 hour until the NCO content drops to 3.5% - 4.0%. Step 3. Auxiliary agent mixing: Add antioxidant and ultraviolet absorber to the product obtained in Step 2, homogenize for 10 minutes, and discharge and store in a sealed manner.

8. The preparation method of a high-strength water-resistant polyurethane adhesive according to claim 7, characterized in that: The curing conditions of the adhesive are: initial curing at 25 °C for 24 hours after coating, and then post-curing at 80 °C for 2 hours.

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