VOC-free thiol-based polyurea composite material as well as preparation method and application thereof

Abstract

The invention discloses a VOC-free thiol-based polyurea composite material as well as a preparation method and application thereof, and belongs to the technical field of bonding materials. The composite material provided by the invention is prepared by the following steps: under the protection of inert gas, adding aspartic polyurea 420 resin into a container, stirring, dropwise adding mixed mercaptan and a catalyst I, and reacting to obtain a hybrid mercaptan amino acid ester intermediate after the reaction is finished; under the protection of inert gas, isocyanate and a solvent are mixed, aminopropyltriethoxysilane and a catalyst II are added for a reaction, impurities are removed after the reaction is finished, and silane modified isocyanate is obtained; and finally, mixing the hybrid thiol amino acid ester intermediate with silane modified isocyanate to obtain the VOC-free thiol-based polyurea composite material. The thiol-based polyurea composite material provided by the invention has a relatively high curing speed, can realize internal and external synchronous curing, and also has excellent adhesive property, ageing resistance and environmental protection property.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adhesive materials, and particularly relates to a VOC-free mercaptan-based polyurea composite material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous improvement of the automation and intelligent production level of the furniture, building materials, decoration and other industries, higher requirements are put forward for production efficiency and environmental protection and health. In the processes of board splicing, ceramic stone composite and inorganic material edge sealing, fast-curing adhesives need to be used to realize instant positioning and rapid shaping, so as to match the high-speed continuous production rhythm.

[0003] Traditional polyaspartic ester polyurea (polyurea) is concerned due to its excellent wear resistance, aging resistance and fast surface drying speed. Although the polyurea has fast surface drying, the internal curing is slow, and the Shore D hardness needs to be above 50 for 40-50 min, which cannot meet the construction efficiency requirement of splicing and shaping, resulting in long waiting time in subsequent processes and affecting the production rhythm. In order to overcome the slow curing defect of polyurea, fast-curing adhesives represented by acrylate, unsaturated polyester, reactive acrylic and traditional mercaptan are used as a replacement scheme in the market. Although this kind of product can realize fast curing, it generally has problems such as strong odor, violent reaction, strong corrosion, high VOC content and easy discoloration.

[0004] Therefore, it is necessary to provide a new VOC-free mercaptan-based polyurea composite material and a preparation method and application thereof. SUMMARY

[0005] Based on the deficiencies of the prior art, the purpose of the present application is to provide a VOC-free mercaptan-based polyurea composite material and a preparation method and application thereof.

[0006] The first aspect of the present application is to provide a preparation method of a VOC-free mercaptan-based polyurea composite material, comprising the following steps: S1: under the protection of inert gas, aspartic polyurea 420 resin is added into a container for stirring, mixed mercaptan and catalyst I are dropped for reaction, and a hybrid type mercaptan amine acid ester intermediate is obtained after the reaction is completed; S2: under the protection of inert gas, isocyanate is mixed with a solvent, and amino propyl triethoxysilane and catalyst II are added for reaction, and a silane-modified isocyanate is obtained after the reaction is completed and impurities are removed; S3: the hybrid type mercaptan amine acid ester intermediate and the silane-modified isocyanate are mixed to obtain the VOC-free mercaptan-based polyurea composite material.

[0007] In some embodiments, the molar ratio of aspartic polyurea 420 resin to mixed thiols is 1:0.8-1; the mixed thiols are composed of cyclohexanedithiol and 1,4-phenylenedimethylthiol in a molar ratio of 0.7-0.75:0.2-0.3.

[0008] In some embodiments, the isocyanate is selected from at least one of HMDI prepolymer with an NCO mass fraction of 18-22% and HDI trimer with an NCO mass fraction of 20-24%; the mass ratio of isocyanate to aminopropyltriethoxysilane is 10:0.1-0.3; the solvent is selected from at least one of anhydrous xylene and n-butyl acetate, and the mass amount of the solvent is 1-3% of the mass of the isocyanate.

[0009] In some embodiments, catalyst one and catalyst two are both selected from at least one of dibutyltin dilaurate and stannous octoate; the mass amount of catalyst one is 0.1-0.3% of the sum of the mass of aspartic polyurea 420 resin and mixed thiols; the mass amount of catalyst two is 0.4-0.6% of the mass of aminopropyltriethoxysilane.

[0010] In some embodiments, the mass ratio of the hybrid thiol amino acid ester intermediate to the silane-modified isocyanate is 1:1.2-1.5.

[0011] In some embodiments, in S1, the container temperature is 40-55°C, the stirring is carried out at 600-800 r / min for 10-15 min, the dropping rate is 1-2 mL / min, the reaction is carried out at 60-70°C and 1000-1200 r / min for 2-3 h with stirring and holding, and the reaction endpoint is when the thiol content of the reaction system reaches 0.3-0.5 mmol / g.

[0012] In some embodiments, in S2, the mixing temperature is 65-75°C, the reaction is carried out at 70-75°C for 2.5-3.5 hours, and the impurity removal is carried out at 75-85°C under a vacuum of -0.09 to -0.1 MPa for 45-75 minutes.

[0013] In some embodiments, in S3, mixing is performed by stirring at 600-800 rpm for 3-5 minutes.

[0014] A second aspect of the present invention is to provide a VOC-free thiol-based polyurea composite material.

[0015] A third aspect of the present invention is to provide an application of a VOC-free thiol-based polyurea composite material in the field of adhesives.

[0016] The VOC-free thiol-based polyurea composite material provided by this invention can be used for edge sealing of furniture, ceramics, or inorganic materials such as stone. During construction, it can be directly applied to the surfaces to be bonded without the need for additional solvents or diluents.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The reactivity of the thiol group (-SH) and isocyanate (-NCO) in the hybrid thiol ester intermediate provided by the present invention is significantly higher than that of the amino group (-NH2) and -NCO in traditional polyurea; and the thiol group is uniformly distributed in the thiol ester molecular chain, which can promote the simultaneous and rapid cross-linking of the surface and the interior, thereby achieving efficient curing and perfectly matching the production rhythm of rapid splicing and shaping.

[0018] 2. This invention creatively combines cyclohexanedithiols with aromatic dithiols, simultaneously introducing flexible segments and rigid benzene rings into the molecular chain to construct a hybrid molecular structure that combines rigidity and flexibility. This endows the product with high hardness and excellent anti-aging ability. In addition, silane groups that can undergo interfacial chemical bonding are implanted into the isocyanate component. The silane component can actively form strong covalent bonds with inorganic substrates, and its bonding strength (especially for ceramics and stone) and durability far exceed those of physical adsorption adhesives.

[0019] 3. The VOC-free thiol-based polyurea composite material provided by this invention has no irritating odor and mild exothermic reaction during construction, overcoming the defects of existing fast-curing adhesives such as corrosion of substrate, high toxicity, and easy yellowing. It has extremely low VOC content and high strength, high durability, and high environmental friendliness. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to specific embodiments.

[0021] Example 1 A method for preparing a VOC-free thiol-based polyurea composite material includes the following steps: S1: Under inert gas protection, aspartic polyurea 420 resin was added to a container at 50°C and stirred at 700 r / min for 12 min. Mixed thiols and dibutyltin dilaurate were then added dropwise at a rate of 1-2 mL / min. The mixture was stirred and kept at 65°C and 1100 r / min for 2.5 h. The reaction was stopped when the thiol content of the reaction system reached 0.4 mmol / g, yielding a hybrid thiol ester intermediate. The molar ratio of aspartic polyurea 420 resin to mixed thiols was 1:0.9. The mixed thiols were composed of cyclohexanedithiol and 1,4-phenylenedimethylthiol in a molar ratio of 0.2:0.25. The mass of dibutyltin dilaurate was 0.2% of the sum of the masses of aspartic polyurea 420 resin and mixed thiols. S2: Under inert gas protection, HMDI prepolymer with an NCO mass fraction of 20% was mixed with anhydrous xylene at 70°C. Aminopropyltriethoxysilane and dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. After the reaction, the mixture was kept at 80°C under a vacuum of -0.095 MPa for 60 minutes to remove impurities, thus obtaining silane-modified isocyanate. The mass ratio of HMDI prepolymer to aminopropyltriethoxysilane was 10:0.2, the mass of anhydrous xylene was 2% of the mass of HMDI prepolymer, and the mass of dibutyltin dilaurate was 0.5% of the mass of aminopropyltriethoxysilane. S3: A VOC-free thiol-based polyurea composite material is obtained by stirring a hybrid thiol amine ester intermediate and a silane-modified isocyanate at a mass ratio of 1:1.35 at 700 rpm for 4 min.

[0022] The VOC-free thiol-based polyurea composite material prepared by the above method can be used for edge sealing of furniture, ceramics, or inorganic materials such as stone. During construction, it can be directly applied to the surface to be bonded without the need for additional solvents or diluents.

[0023] Example 2 A method for preparing a VOC-free thiol-based polyurea composite material includes the following steps: S1: Under inert gas protection, aspartic polyurea 420 resin was added to a container at 55°C and stirred at 800 r / min for 10 min. Mixed thiols and stannous octoate were added dropwise at a rate of 1-2 mL / min. The mixture was stirred and kept at 70°C and 1000 r / min for 3 h. The reaction was stopped when the thiol content of the reaction system reached 0.5 mmol / g, yielding a hybrid thiol ester intermediate. The molar ratio of aspartic polyurea 420 resin to mixed thiols was 1:1. The mixed thiols were composed of a mixture of cyclohexanediol and 1,4-phenylenedimethylthiol in a molar ratio of 0.75:0.3. The mass of stannous octoate was 0.3% of the sum of the masses of aspartic polyurea 420 resin and mixed thiols. S2: Under inert gas protection, HDI trimer with an NCO mass fraction of 22% was mixed with n-butyl acetate at 75°C. Aminopropyltriethoxysilane and stannous octoate were then added and reacted at 75°C for 2.5 h. After the reaction, the mixture was kept at 85°C under a vacuum of -0.1 MPa for 45 min to remove impurities, yielding silane-modified isocyanate. The mass ratio of HDI trimer to aminopropyltriethoxysilane was 10:0.3, the mass of n-butyl acetate was 3% of the isocyanate mass, and the mass of stannous octoate was 0.6% of the aminopropyltriethoxysilane mass. S3: Mix the hybrid thiol amine ester intermediate and the silane-modified isocyanate at a mass ratio of 1:1.5 at 800 rpm for 3 min to obtain a VOC-free thiol-based polyurea composite material.

[0024] Example 3 A method for preparing a VOC-free thiol-based polyurea composite material includes the following steps: S1: Under inert gas protection, aspartic polyurea 420 resin was added to a container at 40°C and stirred at 600 r / min for 15 min. Mixed thiols and dibutyltin dilaurate were then added dropwise at a rate of 1-2 mL / min. The mixture was stirred and kept at 60°C and 1000 r / min for 3 h. The reaction ended when the thiol content in the reaction system reached 0.3 mmol / g, yielding a hybrid thiol ester intermediate. The molar ratio of aspartic polyurea 420 resin to mixed thiols was 1:0.8. The mixed thiols were composed of cyclohexanedithiol and 1,4-phenylenedimethylthiol in a molar ratio of 0.7:0.2. The mass of dibutyltin dilaurate was 0.1% of the sum of the masses of aspartic polyurea 420 resin and mixed thiols. S2: Under inert gas protection, HMDI prepolymer with an NCO mass fraction of 22% was mixed with anhydrous xylene at 65°C. Aminopropyltriethoxysilane and dibutyltin dilaurate were added, and the mixture was reacted at 70°C for 3.5 h. After the reaction, the mixture was kept at 75°C under a vacuum of -0.09 MPa for 75 min to remove impurities, thus obtaining silane-modified isocyanate. The mass ratio of HMDI prepolymer to aminopropyltriethoxysilane was 10:0.1, the mass of anhydrous xylene was 1% of the isocyanate mass, and the mass of dibutyltin dilaurate was 0.4% of the aminopropyltriethoxysilane mass. S3: Mix the hybrid thiol amine ester intermediate and silane-modified isocyanate in a mass ratio of 1:1.2-1.5 at 600 rpm for 5 min to obtain a VOC-free thiol-based polyurea composite material.

[0025] Example 4 A method for preparing a VOC-free thiol-based polyurea composite material includes the following steps: S1: Under inert gas protection, aspartic polyurea 420 resin was added to a container at 45°C and stirred at 650 r / min for 13 min. Mixed thiols and stannous octoate were added dropwise at a rate of 1-2 mL / min. The mixture was stirred and kept at 65°C and 1200 r / min for 3 h. The reaction was stopped when the thiol content of the reaction system reached 0.4 mmol / g, yielding a hybrid thiol ester intermediate. The molar ratio of aspartic polyurea 420 resin to mixed thiols was 1:0.9. The mixed thiols were composed of cyclohexanedithiol and 1,4-phenylenedimethylthiol in a molar ratio of 0.74:0.2. The mass of stannous octoate was 0.3% of the sum of the masses of aspartic polyurea 420 resin and mixed thiols. S2: Under inert gas protection, HDI trimer with an NCO mass fraction of 24% was mixed with n-butyl acetate at 70°C. Aminopropyltriethoxysilane and dibutyltin dilaurate were then added and reacted at 75°C for 3.5 h. After the reaction, the mixture was kept at 75°C under a vacuum of -0.1 MPa for 55 min to remove impurities, yielding silane-modified isocyanate. The mass ratio of HDI trimer to aminopropyltriethoxysilane was 10:0.15, the mass of n-butyl acetate was 1.5% of the isocyanate mass, and the mass of dibutyltin dilaurate was 0.45% of the aminopropyltriethoxysilane mass. S3: A VOC-free thiol-based polyurea composite material is obtained by stirring a hybrid thiol amine ester intermediate and a silane-modified isocyanate at a mass ratio of 1:1.4 at 750 rpm for 4 min.

[0026] Example 5 A method for preparing a VOC-free thiol-based polyurea composite material includes the following steps: S1: Under inert gas protection, aspartic polyurea 420 resin was added to a container at 50°C and stirred at 800 r / min for 15 min. Mixed thiols and dibutyltin dilaurate were then added dropwise at a rate of 1-2 mL / min. The mixture was stirred and kept at 65°C and 1200 r / min for 2.5 h. The reaction ended when the thiol content in the reaction system reached 0.4 mmol / g, yielding a hybrid thiol ester intermediate. The molar ratio of aspartic polyurea 420 resin to mixed thiols was 1:0.9. The mixed thiols were composed of cyclohexanedithiol and 1,4-phenylenedimethylthiol in a molar ratio of 0.7:0.3. The mass of dibutyltin dilaurate was 0.25% of the sum of the masses of aspartic polyurea 420 resin and mixed thiols. S2: Under inert gas protection, HMDI prepolymer with an NCO mass fraction of 18% was mixed with n-butyl acetate at 70°C, and then aminopropyltriethoxysilane and stannous octoate were added and reacted at 75°C for 2.5 h. After the reaction was completed, the mixture was kept at 85°C and under a vacuum of -0.09 MPa for 65 min to remove impurities, thus obtaining silane-modified isocyanate. The mass ratio of HMDI prepolymer with an NCO mass fraction of 18% to aminopropyltriethoxysilane was 10:0.25, the mass amount of n-butyl acetate was 2.5% of the mass of isocyanate, and the mass amount of stannous octoate was 0.55% of the mass of aminopropyltriethoxysilane. S3: A VOC-free thiol-based polyurea composite material is obtained by stirring a hybrid thiol amine ester intermediate and a silane-modified isocyanate at a mass ratio of 1:1.4 at 750 rpm for 4 min.

[0027] Comparative Example 1 It is basically the same as Example 1, except that: the aspartic polyurea 420 resin is not modified, that is, S1 is omitted.

[0028] Comparative Example 2 It is basically the same as Example 1, except that the aspartic polyurea 420 resin in S1 is physically mixed with the mixed thiol.

[0029] Comparative Example 3 It is basically the same as Example 1, except that the HMDI prepolymer is replaced with the same amount of TDI.

[0030] The composite materials prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to performance tests, and the test results are shown in Table 1.

[0031] Surface drying time was determined using the industry-standard finger-touch method at 25℃ and 50% relative humidity, measuring the time required for the paint film surface to become non-sticky when lightly touched with a finger. A Shore D hardness tester was used at 25℃, with the tester vertically pressed onto the surface of the curing sample, measuring every minute and recording the time it took for the hardness to first reach 50. VOC content was determined according to national standard GB / T 33372-2020. UV aging resistance was tested using a QUV UV aging test chamber under the following conditions: UVA-340 lamp, 60℃ UV irradiation for 8 hours, 50℃ condensation for 4 hours, and after 30 days, the color difference (ΔE) between the sample and the initial sample was measured and calculated using a colorimeter. Adhesion strength was tested according to GB / T 7124-2008 standard.

[0032] Table 1 As can be seen from Table 1, the properties of Examples 1-5 are excellent and stable, with a fast curing rate, a surface drying time of less than 4 minutes, and excellent environmental friendliness, aging resistance and bonding strength.

[0033] As can be seen from the comparative examples, Comparative Example 1, lacking highly active thiol groups (-SH), relies solely on the reaction between the amino groups and -NCO groups of the resin itself, resulting in a slow reaction rate and slow construction of the internal cross-linking network, making rapid internal drying impossible. Comparative Example 2, due to physical mixing, has a large amount of small molecule thiols present, which are easily volatilized, causing VOC exceeding the standard, and are easily degraded by ultraviolet light, leading to yellowing. The TDI added in Comparative Example 3 is an aromatic isocyanate, whose benzene ring in its molecular structure easily forms a quinone structure under ultraviolet light, causing yellowing. However, the aliphatic isocyanate (HMDI / HDI) used in this invention does not have this structure, thus exhibiting excellent resistance to yellowing.

[0034] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a VOC-free thiol-based polyurea composite material, characterized in that, Includes the following steps: S1: Under inert gas protection, aspartic polyurea 420 resin is added to a container and stirred. Mixed thiols and catalyst 1 are added dropwise to react. After the reaction is completed, a hybrid thiolsamine ester intermediate is obtained. S2: Under inert gas protection, isocyanate is mixed with solvent, and aminopropyltriethoxysilane and catalyst 2 are added to react. After the reaction is completed, impurities are removed to obtain silane-modified isocyanate. S3: The hybrid thiol amine ester intermediate and the silane-modified isocyanate are mixed to obtain the VOC-free thiol-based polyurea composite material.

2. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, The molar ratio of the aspartic polyurea 420 resin to the mixed thiol is 1:0.8-1; the mixed thiol is composed of cyclohexanedithiol and 1,4-phenylenedimethylthiol in a molar ratio of 0.7-0.75:0.2-0.

3.

3. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, The isocyanate is selected from at least one of HMDI prepolymer with an NCO mass fraction of 18-22% and HDI trimer with an NCO mass fraction of 20-24%; the mass ratio of the isocyanate to the aminopropyltriethoxysilane is 10:0.1-0.3; the solvent is selected from at least one of anhydrous xylene and n-butyl acetate, and the mass amount of the solvent is 1-3% of the mass of the isocyanate.

4. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, Both catalyst one and catalyst two are selected from at least one of dibutyltin dilaurate and stannous octoate; the mass of catalyst one is 0.1-0.3% of the sum of the mass of the aspartic polyurea 420 resin and the mixed thiol; the mass of catalyst two is 0.4-0.6% of the mass of the aminopropyltriethoxysilane.

5. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, The mass ratio of the hybrid thiol amino acid ester intermediate to the silane-modified isocyanate is 1:1.2-1.

5.

6. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, In step S1, the container temperature is 40-55℃, the stirring is carried out at 600-800 r / min for 10-15 min, the dropping rate is 1-2 mL / min, the reaction is carried out at 60-70℃ and 1000-1200 r / min for 2-3 h, and the reaction endpoint is when the thiol content of the reaction system reaches 0.3-0.5 mmol / g.

7. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, In S2, the mixing temperature is 65-75℃, the reaction is carried out at 70-75℃ for 2.5-3.5h, and the impurity removal is carried out at 75-85℃ under a vacuum of -0.09 to -0.1MPa for 45-75min.

8. The method for preparing the VOC-free thiol-based polyurea composite material according to claim 1, characterized in that, In step S3, the mixing is performed by stirring at 600-800 rpm for 3-5 minutes.

9. A VOC-free thiol-based polyurea composite material prepared by the preparation method according to any one of claims 1-8.

10. The application of the VOC-free thiol-based polyurea composite material of claim 9 in the field of adhesives.

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