Preparation process of modified polyurethane adhesive

Abstract

The invention relates to the technical field of polyurethane adhesives, in particular to a preparation process of a modified polyurethane adhesive, which comprises the following steps: S1, selecting the following components in percentage by mass: a component A: 99.9% of hexamethylene diisocyanate, 0.06% of tri-n-butylphosphine and 0.04% of acetone; the component B comprises 50% of lignin, 5% of ethylenediamine, 4% of glutaraldehyde and 1% of a sodium hydroxide solution; the component C comprises 50% of 1, 4-butanediol and 50% of trimethylolpropane; a component D; the coating comprises the following components in percentage by weight: 10% of dibutyltin dilaurate, 35% of ethyl acetate, 45% of nano silicon dioxide and 10% of a stabilizer. The component E comprises 65% of a defoaming agent and 35% of a wetting agent; s2, reacting the component A raw materials to obtain a product A; s3, carrying out reaction on the component B raw materials to obtain a product B; s4, selecting products A, B, C, D and E; s5, mixing and reacting the products A and B; s6, adding the component C; s7, adding the component D; s8, adding the component E, and carrying out defoaming treatment; and S9, sub-packaging and storing. The polyurethane adhesive is more environment-friendly, good in yellowing resistance and high in adaptability in an extreme environment.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane adhesives, and specifically to a preparation process of a modified polyurethane adhesive. Background Art

[0002] Polyurethane adhesives are a kind of high-performance adhesives, which have excellent bonding strength, flexibility, low-temperature resistance and chemical resistance, and are widely used in the fields of automobiles, construction, shoe materials, electronics, etc.

[0003] At present, the commonly used polyurethane adhesives are mostly solvent-based adhesives prepared with polyurethane polymers and polyisocyanates as the main materials. They have the advantages of low production cost, strong bonding force, high initial adhesion, low-temperature resistance and wide application range. However, solvent-based polyurethane adhesives will release a large amount of volatile organic compounds (VOCs) during the film-forming stage and after curing, which not only harms human health but also pollutes the environment. In addition, this type of polyurethane adhesive also has problems such as poor yellowing resistance and poor adaptability in extreme environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation process of a modified polyurethane adhesive to solve the problems of being not environmentally friendly, poor yellowing resistance and poor adaptability in extreme environments existing in the currently commonly used polyurethane adhesives.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A preparation process of a modified polyurethane adhesive, including the following steps:

[0006] S1. Select raw materials;

[0007] Select the following raw materials according to mass percentages:

[0008] Component A: 99.9% of hexamethylene diisocyanate, 0.06% of tri-n-butylphosphine, 0.04% of acetone;

[0009] Component B: 50% of lignin, 5% of ethylenediamine, 4% of glutaraldehyde, 1% of sodium hydroxide solution;

[0010] Component C: 50% of 1,4-butanediol, 50% of trimethylolpropane;

[0011] Component D; 10% of dibutyltin dilaurate, 35% of ethyl acetate, 45% of nano-silica, 10% of stabilizer;

[0012] Component E: 65% of defoamer, 35% of wetting agent;

[0013] S2. Carry out a polymerization reaction on the raw materials of Component A to obtain Product A;

[0014] Among them, the polymerization reaction product is first subjected to molecular evaporation to remove unreacted hexamethylene diisocyanate, and then successively subjected to activated carbon adsorption and vacuum degassing to obtain product A;

[0015] S3. Mix the raw materials of component B to obtain product B;

[0016] S4. Select 30-50 parts of product A, 40-60 parts of product B, 5-10 parts of component C, 10-20 parts of component D, and 3-5 parts of component E by mass;

[0017] S5. Mix and react the selected product A and product B to obtain a prepolymer;

[0018] S6. Add the selected component C to the prepolymer to form a high molecular chain product;

[0019] S7. Add the selected component D to the high molecular chain product for modification;

[0020] S8. Add the selected component E to the modified product and perform vacuum degassing;

[0021] S9. Package and store the product after vacuum degassing.

[0022] Preferably, in the process conditions of the polymerization reaction in step S2, the temperature is 65-85°C to avoid decomposition or yellowing caused by high temperature; the reaction time is 8-11 hours to ensure that the NCO content meets the standard; an inert gas is used for protection during the reaction to prevent oxidation side reactions.

[0023] Preferably, step S3 includes:

[0024] S3.1. Mix lignin and sodium hydroxide solution evenly;

[0025] S3.2. Add ethylenediamine and glutaraldehyde to the mixture and keep the temperature at 70°C for 6 hours of reaction;

[0026] S3.3. Add hydrochloric acid to the reaction product to adjust the pH value to 3;

[0027] S3.4. Collect the precipitate by centrifugation;

[0028] S3.5. Wash the precipitate with water until it is neutral;

[0029] S3.6. Place the washed precipitate in a vacuum environment at 60°C for drying to obtain product B.

[0030] Preferably, the environmental temperature of the reaction in step S5 is 70-85°C.

[0031] Preferably, before adding the selected component C to the prepolymer in step S6, the prepolymer is cooled to 45-55°C.

[0032] Preferably, when adding the selected component C to the prepolymer in step S6, it is added in batches, and stirring is carried out while adding component C. After the addition is completed, stirring is continued for 40-50 minutes.

[0033] Preferably, the stabilizer in component D in step S1 includes an antioxidant and a UV absorber.

[0034] Preferably, when performing vacuum degassing treatment in step S8, the vacuum degree is -0.1 MPa, the temperature is 45-50°C, and the degassing time is 45-60 minutes.

[0035] Preferably, when using an inert gas for protection in step S2, the inert gas is selected from one of nitrogen or argon.

[0036] Preferably, the water content of the dried product B in step S3.6 is less than 0.015%.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] 1. In the preparation process of the modified polyurethane adhesive involved in the present invention, the raw materials of toxic substances are greatly reduced, and the generation of toxic groups during the use of the modified polyurethane adhesive is reduced, which is more environmentally friendly and also greatly reduces the harm to production operators.

[0039] 2. The polyurethane adhesive prepared by the preparation process of the modified polyurethane adhesive involved in the present invention has stable performance under ultra-low temperature and ultraviolet irradiation, good yellowing resistance and weather resistance, and can better adapt to relatively harsh extreme environments. Specific Embodiments

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of 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.

[0041] Embodiment: A preparation process of a modified polyurethane adhesive includes the following steps:

[0042] S1. Select raw materials;

[0043] Select the following raw materials according to mass percentages:

[0044] Component A: 99.9% of hexamethylene diisocyanate, 0.06% of tri-n-butylphosphine, 0.04% of acetone;

[0045] Component B: 50% of lignin, 5% of ethylenediamine, 4% of glutaraldehyde, 1% of sodium hydroxide solution;

[0046] Component C: 50% of 1,4-butanediol, 50% of trimethylolpropane;

[0047] Component D: 10% of dibutyltin dilaurate, 35% of ethyl acetate, 45% of nano-silica, 10% of stabilizer;

[0048] Component E: 65% of defoamer, 35% of wetting agent;

[0049] Among them, the stabilizer in Component D includes antioxidant and UV absorber.

[0050] S2. Polymerize the raw materials of Component A to obtain Product A;

[0051] Among them, the unreacted hexamethylene diisocyanate in the polymerization reaction product is first removed by molecular evaporation, and then Product A is obtained after activated carbon adsorption and vacuum degassing in sequence; in the process conditions of the polymerization reaction, the temperature is 65 - 85°C to avoid decomposition or yellowing caused by high temperature; the reaction time is 8 - 11h to ensure that the NCO content meets the standard; an inert gas is used for protection during the reaction, and one of nitrogen or argon is selected as the inert gas to prevent oxidation side reactions.

[0052] S3. Mix and react the raw materials of Component B to obtain Product B;

[0053] Among them, Step S3 includes:

[0054] S3.1. Mix lignin and sodium hydroxide solution evenly;

[0055] S3.2. Add ethylenediamine and glutaraldehyde to the mixture, and keep the temperature at 70°C for 6 hours for reaction;

[0056] S3.3. Add hydrochloric acid to the reaction product to adjust the pH value to 3;

[0057] S3.4. Collect the precipitate by centrifugation;

[0058] S3.5. Wash the precipitate with water until it is neutral;

[0059] S3.6. Place the washed precipitate in a vacuum environment at 60°C for drying to obtain Product B;

[0060] Among them, the water content of the dried Product B is less than 0.015%.

[0061] S4. Select 30 - 50 parts by mass of product A, 40 - 60 parts of product B, 5 - 10 parts of component C, 10 - 20 parts of component D, and 3 - 5 parts of component E;

[0062] S5. Mix and react the selected product A and product B to obtain a prepolymer; among them, the reaction environmental temperature is 70 - 85°C.

[0063] S6. Add the selected component C to the prepolymer to form a high - molecular - chain product; among them, before adding the selected component C to the prepolymer, first cool the prepolymer to 45 - 55°C; when adding the selected component C to the prepolymer, use a batch - addition method, and stir while adding component C, and continue stirring for 40 - 50 minutes after the addition is completed.

[0064] S7. Add the selected component D to the high - molecular - chain product for modification treatment;

[0065] S8. Add the selected component E to the product after modification treatment and perform vacuum degassing treatment; among them, when performing vacuum degassing treatment, the vacuum degree is - 0.1 MPa, the temperature is 45 - 50°C, and the degassing time is 45 - 60 minutes.

[0066] S9. Package and store the product after vacuum degassing treatment.

[0067] In summary, the residual free isocyanates (such as TDI, MDI) in traditional polyurethane adhesives are toxic and irritating, and long - term exposure may harm human health. In the raw materials for preparing this polyurethane adhesive, product A is used to provide the NCO group, and isocyanate - type raw materials are not used in the direct preparation process of the polyurethane adhesive. Product A has the properties of yellowing resistance and low VOC emissions; in addition, product B is used to provide the OH group, greatly reducing the application of fossil raw materials such as polyols. Thus, the generation of harmful substances in the direct preparation process of the polyurethane adhesive is reduced, making it more environmentally friendly and also greatly reducing the harm to production operators.

[0068] Through the use of nano - carbon dioxide, the heat resistance and hydrolysis resistance of the polyurethane adhesive are improved. The application of lignin in product B improves the bonding strength of the polyurethane adhesive, and lignin enhances the double - dynamic network, that is, introducing covalent bond and hydrogen - bond interactions, making the polyurethane adhesive stable under extreme low - temperature environments, high - humidity environments and strong ultraviolet irradiation, and it can be recycled through ethanol recovery.

[0069] Comparative example: Step 1. Preparation of prepolymer: React polyol with excessive isocyanate at 60 - 90°C to generate an NCO - terminated prepolymer.

[0070] Step 2. Chain extension and cross - linking: Add a chain extender (butanediol) to form a high - molecular chain.

[0071] Step 3, modification treatment: Add fillers, solvents, etc., and adjust the viscosity and properties.

[0072] Step 4, degassing and packaging: After vacuum degassing, subpackage.

[0073] Among them, the mass percentages of each raw material component are as follows: isocyanate 35%, polyester polyol 45%, chain extender (1,4-butanediol) 8%, catalyst 0.4%, filler (calcium carbonate) 11.6%.

[0074] Apply several adhesive strips of the polyurethane adhesives prepared in the examples and comparative examples on clean glass plates respectively. After curing, divide the two formed adhesive films into three groups each, and place them in a xenon lamp aging tester respectively. After accelerating aging for 1000 h, test the yellow index. Then use a contact angle measuring instrument to test the water angle of the adhesive films respectively, and the test results are shown in Table 1. Then conduct peel strength and tensile strength tests on each group of adhesive strips respectively, and the test results are shown in Table 2.

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079] In the embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in electrical, mechanical or other forms.

[0080] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0081] In addition, in each embodiment of the present invention, each functional unit can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0082] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A process for preparing a modified polyurethane adhesive, characterized in that: The following steps are involved: S1. Select raw materials; Select the following raw materials according to mass percentage: Component A: 99.9% hexamethylene diisocyanate, 0.06% tri-n-butylphosphine, 0.04% acetone; Component B: 50% lignin, 5% ethylenediamine, 4% glutaraldehyde, 1% sodium hydroxide solution; Component C: 1,4-butanediol 50%, trimethylolpropane 50%; Component D: 10% dibutyltin dilaurate, 35% ethyl acetate, 45% nano-silicon dioxide, 10% stabilizer; Component E: defoamer 65%, wetting agent 35%; S2, polymerizing the raw material of component A to obtain product A; The polymerization product is first subjected to molecular evaporation to remove unreacted hexamethylene diisocyanate, and then subjected to activated carbon adsorption and vacuum degassing in sequence to obtain product A; S3, mixing the raw materials of component B to react to obtain product B; S4, select 30-50 parts of product A, 40-60 parts of product B, 5-10 parts of component C, 10-20 parts of component D, and 3-5 parts of component E by mass; S5, mixing the selected product A and product B to react to obtain a prepolymer; S6, adding the selected C component to the prepolymer to form a polymer chain product; S7, adding the selected D component to the polymer chain product to perform modification treatment; S8, adding the selected E component to the modified product, and performing vacuum degassing treatment; S9. Pack and store the products after vacuum degassing.

2. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: The process conditions for the polymerization reaction in step S2 are a temperature of 65-85° C. and a time of 8-11 hours, and an inert gas protection is used during the reaction.

3. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: The step S3 comprises: S3.1, mix lignin and sodium hydroxide solution evenly; S3.2, adding ethylenediamine and glutaraldehyde to the mixture, maintaining the temperature at 70°, and reacting for 6 hours; S3.3, adding hydrochloric acid to the reaction product to adjust the pH value to 3; S3.4, collecting the precipitate by centrifugation; S3.5, wash the precipitate with water until it becomes neutral; S3.

6. Dry the washed precipitate in a vacuum environment at 60°C to obtain product B.

4. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: The ambient temperature in step S5 is 70-85°C.

5. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: In the step S6, the prepolymer is cooled to 45-55° C. before adding the selected C component to the prepolymer.

6. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: In step S6, when adding the selected component C to the prepolymer, the prepolymer is added in batches, and stirring is performed while adding the component C. After the addition is completed, stirring is continued for 40 to 50 minutes.

7. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: The stabilizer in the component D in step S1 includes an antioxidant and a UV absorber.

8. The preparation process of a modified polyurethane adhesive according to claim 1, characterized in that: When the vacuum degassing treatment is performed in step S8, the vacuum degree is -0.1 MPa, the temperature is 45-50° C., and the degassing time is 45-60 minutes.

9. The preparation process of a modified polyurethane adhesive according to claim 2, characterized in that: When inert gas protection is adopted in step S2, the inert gas is selected from nitrogen or argon.

10. The preparation process of a modified polyurethane adhesive according to claim 3, characterized in that: The moisture content of the B product after drying in step S3.6 is less than 0.015%.

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