Environment-friendly anti-discoloration adhesive with stone adaptability and preparation method of environment-friendly anti-discoloration adhesive

Abstract

The invention relates to the technical field of adhesives, in particular to an environment-friendly anti-discoloration adhesive with stone adaptability and a preparation method of the environment-friendly anti-discoloration adhesive. The invention relates to an environment-friendly anti-discoloration adhesive with stone adaptability. Comprising the following preparation raw materials: 90-100 parts of epoxy resin E-51, 25-30 parts of a high-temperature-resistant anti-tarnish polyurethane prepolymer, 10-12 parts of a modified tackifier, 1-1.5 parts of a composite coupling agent, 0.5-0.7 part of an antioxidant, 2-3 parts of an ultraviolet absorbent, 10-15 parts of calcium carbonate, 8-12 parts of a diluent benzyl glycidyl ether and 7-10 parts of a curing agent. The environment-friendly anti-discoloration adhesive with the stone adaptability is excellent in bonding strength, water resistance, aging resistance, heat resistance and the like, has good environment-friendly characteristic and comprehensive performance improvement effect, and meets the high-degree stone market requirements.

Description

Technical Field

[0001] The present application relates to the technical field of adhesives, and in particular to an environmentally friendly anti-discoloration adhesive with stone adaptability and a preparation method thereof. Background Art

[0002] As the main style type of exterior decoration of modern urban buildings, dry hanging stone occupies a large proportion in the high-end building decoration market due to its advantages such as natural beauty, green environmental protection, health and safety. With the emergence of stone dry hanging technology, more and more stone adhesives are becoming familiar to people. Compared with the traditional cement "wet laying" process, stone dry hanging has the characteristics of high bonding strength, good toughness and no cracking, good weather resistance, thus avoiding the problems of stone falling off, alkali return, water stains, rust and so on caused by traditional technology.

[0003] Epoxy resin has a series of excellent properties such as bonding, corrosion resistance, and high strength. It has a small shrinkage rate when solidified, has a strong bond with most building materials, and has a wide range of curing conditions. The dry hanging glue on the market currently mainly uses epoxy resin as the main raw material. It is prepared by mixing with a curing agent when used. It is widely used in the field of building materials. The role of dry hanging glue in the stone dry hanging process is crucial. The quality of bonding directly affects the durability and safety of the curtain wall structure. The current epoxy adhesive used for dry hanging stone is also prone to discoloration and yellowing after long-term use, and the bonding strength deteriorates, which cannot meet market demand well. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present application provides an environmentally friendly anti-discoloration adhesive with stone adaptability and a preparation method thereof. The environmentally friendly anti-discoloration adhesive with stone adaptability prepared in the present application has excellent bonding strength, water resistance, aging resistance and heat resistance, and excellent durability, meeting the high demands of the stone market.

[0005] In the first aspect, the present application provides an environmentally friendly anti-discoloration adhesive with stone adaptability, which adopts the following technical solution: The invention discloses an environmentally friendly anti-discoloration adhesive with stone adaptability, which comprises the following raw materials by weight: 90-100 parts of epoxy resin E-51, 25-30 parts of high temperature resistant anti-discoloration polyurethane prepolymer, 10-12 parts of modified tackifier, 1-1.5 parts of composite coupling agent, 0.5-0.7 parts of antioxidant, 2-3 parts of ultraviolet absorber, 10-15 parts of calcium carbonate, 8-12 parts of diluent benzyl glycidyl ether and 7-10 parts of curing agent.

[0006] By adopting the above technical solutions, epoxy resin E-51 is used as the matrix resin to provide the basic bonding strength and mechanical properties of the adhesive. Its high cross-linking density ensures the durability of stone bonding. It forms a complementary network structure with the functional groups (such as borate ester and ethyl acrylate groups) in the polyurethane prepolymer, enhancing heat resistance and shear resistance. The high-temperature resistant and anti-discoloration polyurethane prepolymer provides high-temperature resistance and anti-discoloration properties. Through a specific reaction mechanism (such as the polycondensation reaction of diphenylmethane diisocyanate and polypropylene glycol ether diol), a polyurethane with special functional groups is formed, enhancing the mechanical properties of the material. It acts synergistically with epoxy resin E-51 and the curing agent to further improve the heat resistance and anti-discoloration ability of the adhesive. The modified tackifier is composed of butyl epoxy oleate and modified lignin, improving the bonding strength and ductility of the adhesive. Modified lignin undergoes microwave-assisted acidolysis and demethylation treatment, reacts with 5-bromo-2-methylpentan-2-ol, delaying the curing time and enhancing the bonding strength. Butyl epoxy oleate increases the flexibility and adhesion of the adhesive. The composite coupling agent improves the interfacial bonding between inorganic fillers (such as calcium carbonate) and organic resins, enhancing the overall mechanical properties and water resistance. It acts synergistically with calcium carbonate and other fillers to enhance the comprehensive properties of the adhesive. By forming chemical bonds with the hydroxyl groups on the stone surface through the coupling agent, the interfacial bonding force is enhanced. It synergistically enhances water resistance with the borate ester groups in the polyurethane, reducing interfacial failure in a humid and hot environment. The antioxidant inhibits oxidation reactions and prolongs the service life of the adhesive. It acts synergistically with the ultraviolet absorber and the curing agent to comprehensively protect the adhesive from environmental factors. The ultraviolet absorber absorbs ultraviolet rays to prevent the adhesive from discoloring or degrading due to ultraviolet irradiation. It acts synergistically with the antioxidant and the curing agent to improve the weather resistance and stability of the adhesive. Calcium carbonate is used as a filler to reduce costs and improve the rheological properties and mechanical strength of the adhesive. It acts synergistically with the composite coupling agent to improve the bonding force between the filler and the resin. The diluent benzyl glycidyl ether reduces the viscosity of the adhesive, facilitating construction, and at the same time participates in the curing reaction, improving the properties after curing. It acts synergistically with the curing agent to optimize the curing process and improve the anti-discoloration properties after curing. The curing agent promotes the curing of epoxy resin and has an anti-discoloration function. It acts synergistically with epoxy resin E-51 and the high-temperature resistant and anti-discoloration polyurethane prepolymer to further improve the overall performance of the adhesive. In summary, each component plays a different role in the environmentally friendly anti-discoloration adhesive. Through synergistic effects, the excellent bonding strength, water resistance, aging resistance, and heat resistance of the adhesive are jointly achieved, meeting the requirements of the high-end stone market.

[0007] Preferably, the preparation method of the high-temperature resistant and discoloration-proof polyurethane prepolymer is as follows: by mass parts, add 51 parts of diphenylmethane diisocyanate, 7.6 parts of isocyanate ethyl acrylate, and 350 parts of N,N-dimethylformamide into a reaction kettle, stir evenly under nitrogen protection; then add 32 parts of trans-3-hydroxyallylboronic acid pinacol ester, 33 parts of polypropylene oxide ether diol, and 7 parts of dibutyltin dilaurate, and react at 70-75 °C for 120-150 minutes; then add 0.2 parts of 4-allyl-2,6-di-tert-butylphenol, 4.5 parts of (ferrocenyl)hexanethiol, and 8 parts of tripropylamine, react at a temperature of 70-75 °C for 60-70 minutes, and distill off N,N-dimethylformamide to obtain the high-temperature resistant and discoloration-proof polyurethane prepolymer.

[0008] By adopting the above technical solution, the reaction mechanism of the high-temperature resistant and discoloration-proof polyurethane prepolymer is as follows: Formation of polyurethane: Diphenylmethane diisocyanate and isocyanate ethyl acrylate react with trans-3-hydroxyallylboronic acid pinacol ester and polypropylene oxide ether diol by polycondensation reaction to form a polyurethane with boronic acid pinacol ester and ethyl acrylate groups; the introduction of these groups provides the necessary functional groups for the subsequent thiol-allyl reaction, and also provides additional functionality for the final polymer, enhancing the mechanical properties of the material. The thiol-allyl reaction of 4-allyl-2,6-di-tert-butylphenol and (ferrocenyl)hexanethiol further introduces two structures, ferrocene and tert-butylphenol; the combined action of ferrocene, borate ester and tert-butylphenol significantly improves the heat resistance of the material and reduces the possibility of discoloration of the adhesive.

[0009] Preferably, the modified tackifier is composed of butyl epoxy oleate and modified lignin in a mass ratio of 3:2-3.

[0010] By adopting the above technical solutions, the modified lignin in the modified tackifier is obtained by reacting with 5-bromo-2-methylpentan-2-ol after microwave-assisted acidolysis and demethylation of lignin, which can significantly improve the bonding strength of the adhesive. The modified lignin can also effectively delay the curing time of the adhesive, thus facilitating the construction operation. As a highly efficient tackifier, butyl epoxy oleate can improve the wettability and adhesion of the adhesive to the stone surface, further enhancing the bonding effect. The combined action of butyl epoxy oleate and modified lignin significantly improves the bonding strength of the adhesive through the crosslinking points provided by the modified lignin and the tackifying effect of butyl epoxy oleate. Butyl epoxy oleate helps to regulate the curing speed, which complements the effect of the modified lignin in delaying the curing time, making the adhesive have better operability and pot life during the construction process. The combination of the tackifying effect of butyl epoxy oleate and the modification effect of the modified lignin endows the adhesive with more excellent comprehensive properties in terms of bonding strength, water resistance, aging resistance, etc. Both butyl epoxy oleate and modified lignin are environmentally friendly materials, meeting the environmental protection requirements, and further improving the environmental performance of the adhesive under their combined action. The modified tackifier is composed of butyl epoxy oleate and modified lignin in a mass ratio of 3:2 - 3, and plays an important role in the preparation of an environmentally friendly anti-discoloration adhesive with stone adaptability. Through their synergistic effect, not only the bonding strength of the adhesive is significantly improved and the curing time is delayed, but also its comprehensive properties are optimized, making it more suitable for the high-demand stone market.

[0011] Preferably, the preparation method of the modified lignin includes the following steps: S41. According to the mass parts, add 15 parts of lignin into 130 parts of formic acid, place it in a microwave reactor, react at 1000 - 1500 W and 120 - 130 °C for 40 - 50 minutes, then extract with ethyl acetate three times and rotary evaporate to obtain lignin oligomers; S42. According to the mass parts, add 15 parts of lignin oligomers into 75 parts of N,N-dimethylformamide, then add 90 parts of 30 wt% hydrobromic acid aqueous solution and 1 part of tetrabutylammonium bromide, react at 110 - 120 °C for 20 - 24 h, wash with water and rotary evaporate to obtain demethylated lignin oligomers; S43. According to the mass parts, under a nitrogen atmosphere, add 15 parts of demethylated lignin oligomers into 90 parts of N,N-dimethylformamide, then add 15 parts of 5-bromo-2-methylpentan-2-ol and 22 parts of sodium carbonate, react at 75 - 80 °C for 20 - 24 h, wash with water and rotary evaporate to obtain modified lignin.

[0012] By adopting the above technical solutions, the modified lignin is obtained by reacting lignin with 5-bromo-2-methylpentan-2-ol after microwave-assisted acidolysis and demethylation, which can achieve the effects of delaying the curing time and improving the bonding strength.

[0013] Preferably, the composite coupling agent is composed of γ-aminopropyltriethoxysilane, vinyltriethoxysilane, and γ-ureidopropyltrimethoxysilane in a mass ratio of 3:4:3.

[0014] By adopting the above technical solution, the composite coupling agent forms chemical bonds with the hydroxyl groups on the stone surface through the coupling agent, thereby enhancing the interfacial bonding force between the inorganic filler (such as calcium carbonate) and the organic resin. The enhancement of this interfacial bonding force helps to improve the overall mechanical properties and water resistance of the adhesive. The γ-aminopropyltriethoxysilane and vinyltriethoxysilane in the composite coupling agent act synergistically with the borate groups in the polyurethane to enhance the water resistance of the adhesive. This means that under humid and hot environments, the interfacial failure of the adhesive will be reduced, thus improving the durability and stability of the material. The composite coupling agent acts synergistically with calcium carbonate to enhance the comprehensive properties of the adhesive. This includes improving the bonding strength, aging resistance, and heat resistance of the adhesive. The synergistic effect among γ-aminopropyltriethoxysilane, vinyltriethoxysilane, and γ-ureidopropyltrimethoxysilane may be reflected in their chemical structures and reactivities. These compounds may interact with the resin and filler through different reaction paths and mechanisms, thereby achieving a comprehensive improvement in the properties of the adhesive.

[0015] Preferably, the antioxidant is composed of antioxidant 1010 and antioxidant 1076 in a mass ratio of 2:3.

[0016] Preferably, the ultraviolet absorber is composed of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531 in a mass ratio of 4:3.

[0017] By adopting the above technical solution, the ultraviolet absorber prevents the adhesive from degrading and discoloring due to ultraviolet irradiation. Specifically, the ultraviolet absorber is composed of 2-hydroxy-4-n-octyloxybenzophenone (OHBP) and ultraviolet absorber UV531 in a mass ratio of 4:3. 2-hydroxy-4-n-octyloxybenzophenone (OHBP) is an efficient ultraviolet light absorber that can effectively absorb ultraviolet light, especially short-wave ultraviolet light (UVC and UVB), thereby reducing the damage of ultraviolet light to the adhesive. OHBP has good thermal stability and can maintain its effectiveness at higher temperatures, making it suitable for applications that require heat resistance. Ultraviolet absorber UV531 is a broad-spectrum ultraviolet absorber that can effectively absorb long-wave ultraviolet light (UVA) and part of visible light, providing a wide range of protection. When added to the adhesive, UV531 does not significantly affect its transparency, so it is suitable for products that require a transparent appearance. OHBP and UV531 are complementary in absorbing ultraviolet light. OHBP mainly absorbs short-wave ultraviolet light, while UV531 mainly absorbs long-wave ultraviolet light. The combination of the two can provide more comprehensive ultraviolet protection. The synergistic effect of OHBP and UV531 can not only effectively prevent discoloration caused by ultraviolet light, but also enhance the overall weather resistance of the adhesive and extend its service life. The combination of the thermal stability of OHBP and the broad-spectrum absorption characteristics of UV531 enables the adhesive to maintain stable performance under different environmental conditions and reduce the performance degradation caused by environmental factors. By effectively absorbing ultraviolet light, OHBP and UV531 can significantly reduce the discoloration of the adhesive during long-term exposure to sunlight and maintain the consistency of its appearance. The synergistic effect enhances the anti-aging ability of the adhesive, enabling it to still maintain good physical properties and bonding strength after long-term use. In synergistic action with other components (such as high-temperature anti-discoloration polyurethane prepolymer, modified tackifier, etc.), the overall performance of the adhesive is further improved, making it more suitable for the high-demand stone market. In summary, through the synergistic effect of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531, the ultraviolet absorber effectively improves the ultraviolet protection ability and weather resistance of the adhesive, ensuring its stability and aesthetics under various environmental conditions.

[0018] Preferably, the preparation method of the curing agent is as follows: by mass, mix N-benzyl dimethylamine, isophorone diamine and benzyl alcohol, adjust the temperature to 35-40 °C, start stirring, and dropwise add 1,4-butanediol diglycidyl ether. The dropping is completed in 4 hours, adjust the temperature to 42-45 °C, continue the reaction for 80-90 minutes, and cool to 30 °C to obtain the curing agent.

[0019] Preferably, the mass ratio of N-benzyl dimethylamine, isophorone diamine, benzyl alcohol and 1,4-butanediol diglycidyl ether is 4:2:4:5.

[0020] By adopting the above technical solution, the curing agent is prepared from N-benzyl dimethylamine, isophorone diamine, benzyl alcohol and 1,4-butanediol diglycidyl ether as raw materials. Among them, N-benzyl dimethylamine and isophorone diamine are low-viscosity curing agents and are basic amine curing agents, while 1,4-butanediol diglycidyl ether is a modifier for the basic amine curing agent. After they react with each other, the curing agent is prepared. At the same time, the added benzyl alcohol can, firstly, reduce the concentration of reactants in the system, secondly, relieve the temperature rise after the reaction exotherm, and thirdly, act as a diluent and a curing agent. Therefore, they interact with each other and by optimizing their dosages, a curing agent with low viscosity and excellent anti-discoloration performance can be obtained.

[0021] In a second aspect, the present application provides a preparation method of an environmentally friendly anti-discoloring adhesive with stone adaptability, adopting the following technical solution: As a general technical concept, the present application also provides the preparation method of the above-mentioned environmentally friendly anti-discoloring adhesive with stone adaptability, including the following steps: By mass parts, put epoxy resin E-51, high-temperature resistant anti-discoloring polyurethane prepolymer, modified tackifier, composite coupling agent, antioxidant, ultraviolet absorber, calcium carbonate and diluent benzyl glycidyl ether into a reactor, stir at 70 - 75 °C for 60 - 70 minutes, then cool down to 30 °C and add the curing agent and stir for 10 - 15 minutes to obtain the environmentally friendly anti-discoloring adhesive with stone adaptability.

[0022] In a third aspect, the present application provides an application of an environmentally friendly anti-discoloring adhesive with stone adaptability, adopting the following technical solution: As a general technical concept, the present application also provides the application of the above-mentioned environmentally friendly anti-discoloring adhesive with stone adaptability, specifically, after the environmentally friendly anti-discoloring adhesive with stone adaptability is cured, it is pulverized and ground to obtain a rubber powder, and the rubber powder is applied in an artificial stone binder. The artificial stone binder, by mass parts, includes the following preparation raw materials: 30 - 40 parts of sulfoaluminate cement, 30 - 40 parts of aggregate, 10 - 25 parts of rubber powder, 3 - 5 parts of cellulose, and 1 - 3 parts of lignin fiber. Among them, the aggregate includes natural aggregates such as river sand, sea sand and mountain stone; artificial aggregates such as crushed stone and manufactured sand. Using this rubber powder can significantly improve the adhesion of the artificial stone binder and reduce the possibility of discoloration.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. Excellent bonding strength: By using epoxy resin E-51 and high-temperature resistant anti-discoloring polyurethane prepolymer as main components, the adhesive has a high bonding strength and can firmly bond stone and other materials.

[0024] 2. Water resistance: The use of modified tackifiers and curing agents improves the water resistance of the adhesive, enabling it to maintain good bonding performance in humid environments.

[0025] 3. Aging resistance: By introducing ultraviolet absorbers and antioxidants, the adhesive can effectively resist the damage of ultraviolet rays and oxidants to the material, extending its service life.

[0026] 4. Heat resistance: The special structure and reaction mechanism of the high-temperature resistant and discoloration-proof polyurethane prepolymer enhance the heat resistance of the adhesive, enabling it to maintain stable performance in high-temperature environments.

[0027] 5. Environmental friendliness: The adhesive in this application uses environmentally friendly materials and processes, reducing environmental pollution and meeting the requirements of sustainable development.

[0028] 6. Comprehensive performance improvement: By using a composite coupling agent, the interfacial bonding between the inorganic filler and the organic resin of the adhesive is improved, and the overall mechanical properties and water resistance are enhanced. At the same time, the use of modified lignin also improves the bonding strength. Specific implementation manners

[0029] The following will describe the implementation schemes of this application in detail in combination with examples. However, those skilled in the art will understand that the following examples are only used to illustrate this application and should not be regarded as limiting the scope of this application. For those not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0030] In the following examples and preparation examples, 1 part means 50 g.

[0031] Preparation Example 1 Preparation of high-temperature resistant and discoloration-proof polyurethane prepolymer The preparation method of the high-temperature resistant and discoloration-proof polyurethane prepolymer is as follows: According to the mass parts, add 51 parts of diphenylmethane diisocyanate, 7.6 parts of isocyanate ethyl acrylate, and 350 parts of N,N-dimethylformamide into the reaction kettle, stir evenly under nitrogen protection; then add 32 parts of trans-3-hydroxyallylboronic acid pinacol ester, 33 parts of polypropylene oxide ether diol, and 7 parts of dibutyltin dilaurate, and react at 70 - 75 °C for 120 - 150 minutes; then add 0.2 part of 4-allyl-2,6-di-tert-butylphenol, 4.5 parts of (ferrocenyl) hexanethiol, and 8 parts of tripropylamine, the reaction temperature is 73 °C, and the time is 65 minutes. Distill off N,N-dimethylformamide to obtain the high-temperature resistant and discoloration-proof polyurethane prepolymer.

[0032] Preparation Example 2 Preparation of modified lignin The preparation method of modified lignin includes the following steps: S41, adding 15 parts of lignin to 130 parts of formic acid according to the mass fraction, placing in a microwave reactor, reacting at 1300W and 125°C for 45 minutes, then extracting with ethyl acetate for 3 times, and rotary evaporating to obtain lignin oligomers; S42, according to the mass fractions, add 15 parts of lignin oligomers to 75 parts of N,N-dimethylformamide, then add 90 parts of 30wt% hydrobromic acid aqueous solution and 1 part of tetrabutylammonium bromide, react at 115°C for 22h, wash with water, and rotary evaporate to obtain demethylated lignin oligomers; S43. According to the mass proportions, under a nitrogen atmosphere, 15 parts of demethylated lignin oligomers were added to 90 parts of N,N-dimethylformamide, and then 15 parts of 5-bromo-2-methylpentan-2-ol and 22 parts of sodium carbonate were added. The mixture was reacted at 78°C for 22 hours, washed with water, and rotary evaporated to obtain modified lignin.

[0033] Preparation Example 3 Preparation of curing agent The preparation method of the curing agent is as follows: according to the mass parts, 40 parts of N-benzyldimethylamine, 20 parts of isophoronediamine and 40 parts of benzyl alcohol are mixed, the temperature is adjusted to 38°C, stirring is started, 50 parts of 1,4-butanediol diglycidyl ether are added dropwise, the addition is completed in 4 hours, the temperature is adjusted to 44°C, the reaction is continued for 86 minutes, and the curing agent is obtained by cooling to 30°C.

[0034] Preparation of Comparative Example 1 Preparation of polyurethane prepolymer The same as Preparation Example 1, except that the amount of 4-allyl-2,6-di-tert-butylphenol added is 0 parts.

[0035] Preparation of Comparative Example 2 Preparation of polyurethane prepolymer The same as Preparation Example 1, except that the amount of trans-3-hydroxypropylene boric acid pinacol ester added is 0 parts.

[0036] Example 1 An environmentally friendly anti-discoloration adhesive with stone adaptability, comprising the following raw materials by weight: 90 parts of epoxy resin E-51, 25 parts of high temperature resistant anti-discoloration polyurethane prepolymer, 10 parts of modified tackifier, 1 part of composite coupling agent, 0.5 parts of antioxidant, 2 parts of ultraviolet absorber, 10 parts of calcium carbonate, 8 parts of diluent benzyl glycidyl ether, and 7 parts of curing agent, wherein the modified tackifier is composed of epoxy butyl oleate and modified lignin in a mass ratio of 3:2, the composite coupling agent is composed of γ-aminopropyl triethoxysilane, vinyl triethoxysilane and γ-ureapropyl trimethoxysilane in a mass ratio of 3:4:3, the antioxidant is composed of antioxidant 1010 and antioxidant 1076 in a mass ratio of 2:3, and the ultraviolet absorber is composed of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531 in a mass ratio of 4:3; The preparation method of the above-mentioned environmentally friendly anti-discoloration adhesive with stone adaptability comprises the following steps: According to the mass parts, put epoxy resin E-51, high-temperature resistant anti-discoloration polyurethane prepolymer, modified tackifier, composite coupling agent, antioxidant, ultraviolet absorber, calcium carbonate and diluent benzyl glycidyl ether into a reactor, stir at 70 °C for 70 minutes, then cool down to 30 °C and add a curing agent and stir for 10 minutes to obtain the environmentally friendly anti-discoloration adhesive with stone adaptability.

[0037] Example 2 An environmentally friendly anti-discoloration adhesive with stone adaptability, by mass parts, comprises the following preparation raw materials: 100 parts of epoxy resin E-51, 30 parts of high-temperature resistant anti-discoloration polyurethane prepolymer, 12 parts of modified tackifier, 1.5 parts of composite coupling agent, 0.7 part of antioxidant, 3 parts of ultraviolet absorber, 15 parts of calcium carbonate, 12 parts of diluent benzyl glycidyl ether, 10 parts of curing agent. The modified tackifier is composed of butyl epoxy oleate and modified lignin in a mass ratio of 3:3. The composite coupling agent is composed of γ-aminopropyltriethoxysilane, vinyltriethoxysilane and γ-ureidopropyltrimethoxysilane in a mass ratio of 3:4:3. The antioxidant is composed of antioxidant 1010 and antioxidant 1076 in a mass ratio of 2:3. The ultraviolet absorber is composed of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531 in a mass ratio of 4:3; The preparation method of the above-mentioned environmentally friendly anti-discoloration adhesive with stone adaptability comprises the following steps: According to the mass parts, put epoxy resin E-51, high-temperature resistant anti-discoloration polyurethane prepolymer, modified tackifier, composite coupling agent, antioxidant, ultraviolet absorber, calcium carbonate and diluent benzyl glycidyl ether into a reactor, stir at 75 °C for 60 minutes, then cool down to 30 °C and add a curing agent and stir for 15 minutes to obtain the environmentally friendly anti-discoloration adhesive with stone adaptability.

[0038] Example 3 An environmentally friendly anti-discoloration adhesive with stone adaptability, by mass parts, comprises the following preparation raw materials: 95 parts of epoxy resin E-51, 27 parts of high-temperature resistant anti-discoloration polyurethane prepolymer, 11 parts of modified tackifier, 1.3 parts of composite coupling agent, 0.6 part of antioxidant, 2.5 parts of ultraviolet absorber, 13 parts of calcium carbonate, 10 parts of diluent benzyl glycidyl ether, 8.5 parts of curing agent. The modified tackifier is composed of butyl epoxy oleate and modified lignin in a mass ratio of 3:2.5. The composite coupling agent is composed of γ-aminopropyltriethoxysilane, vinyltriethoxysilane and γ-ureidopropyltrimethoxysilane in a mass ratio of 3:4:3. The antioxidant is composed of antioxidant 1010 and antioxidant 1076 in a mass ratio of 2:3. The ultraviolet absorber is composed of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531 in a mass ratio of 4:3; The preparation method of the above-mentioned environmentally friendly anti-discoloration adhesive with stone adaptability comprises the following steps: According to the mass parts, put epoxy resin E-51, high-temperature resistant anti-discoloration polyurethane prepolymer, modified tackifier, composite coupling agent, antioxidant, ultraviolet absorber, calcium carbonate and diluent benzyl glycidyl ether into a reactor, stir at 73 °C for 66 minutes, then cool down to 30 °C and add the curing agent and stir for 13 minutes to obtain the environmentally friendly anti-discoloration adhesive with stone adaptability.

[0039] Comparative Example 1 Same as Example 3, the difference is that: use the polyurethane prepolymer prepared in Comparative Example 1 with the same mass parts to replace the high-temperature resistant anti-discoloration polyurethane prepolymer.

[0040] Comparative Example 2 Same as Example 3, the difference is that: use the polyurethane prepolymer prepared in Comparative Example 2 with the same mass parts to replace the high-temperature resistant anti-discoloration polyurethane prepolymer.

[0041] Comparative Example 3 Same as Example 3, the difference is that: the composite coupling agent is γ-aminopropyltriethoxysilane.

[0042] Comparative Example 4 Same as Example 3, the difference is that: the composite coupling agent is vinyltriethoxysilane.

[0043] Comparative Example 5 Same as Example 3, the difference is that: the composite coupling agent is γ-ureidopropyltrimethoxysilane.

[0044] Comparative Example 6 Same as Example 3, the difference is that: the ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone.

[0045] Comparative Example 7 Same as Example 3, except that: the ultraviolet absorber is ultraviolet absorber UV531.

[0046] Comparative Example 8 Same as Example 3, except that: the modified tackifier is butyl epoxy oleate.

[0047] Comparative Example 9 Same as Example 3, except that: the modified tackifier is modified lignin.

[0048] Performance detection test Samples of the environmentally friendly anti-discoloration adhesives with stone adaptability prepared in the above Examples 1 - 3 and Comparative Examples 1 - 9 were taken respectively, and the relevant properties were tested according to JC / T547 - 2017. The results are shown in Table 1.

[0049] Among them, for the heat resistance test: a thermogravimetric analyzer (TA Instruments TGAQ50, USA) was used for testing; the heating rate: 10 °C / minute; the test atmosphere: air.

[0050] Table 1 Performance test Analyzing the data in Table 1, it can be seen that: 1) The environmentally friendly anti-discoloration adhesives with stone adaptability prepared in Examples 1 - 3 have excellent bonding strength, water resistance, aging resistance and heat resistance, with excellent durability performance, meeting the requirements of the high-end stone market.

[0051] 2) The performance comparison and analysis of the environmentally friendly anti-discoloration adhesives with stone adaptability prepared in Example 3 and Comparative Examples 1 - 2 show that the high-temperature resistant anti-discoloration polyurethane prepolymer prepared in this application undergoes a polycondensation reaction through diphenylmethane diisocyanate and isocyanate ethyl acrylate with trans - 3 - hydroxyallylboronic acid pinacol ester and poly(propylene oxide) glycol to form a polyurethane with boronic acid pinacol ester and acrylate groups; the introduction of these groups provides the necessary functional groups for the subsequent thiol-allyl reaction, and also provides additional functionality for the final polymer, enhancing the mechanical properties of the material. The thiol-allyl reaction of 4-allyl-2,6-di-tert-butylphenol with (ferrocenyl)hexanethiol further introduces two structures, ferrocene and tert-butylphenol; the combined action of ferrocene with borate ester and tert-butylphenol significantly improves the heat resistance of the material and reduces the possibility of discoloration of the adhesive.

[0052] 3) Comparative analysis of the performance of the environmentally friendly anti-discoloration adhesives with stone adaptability prepared in Example 3 and Comparative Examples 4 - 6 shows that the composite coupling agent consists of γ-aminopropyltriethoxysilane, vinyltriethoxysilane, and γ-ureidopropyltrimethoxysilane in a mass ratio of 3:4:3. By utilizing their synergistic effect, the comprehensive performance of the adhesive is significantly improved.

[0053] 4) Comparative analysis of the performance of the environmentally friendly anti-discoloration adhesives with stone adaptability prepared in Example 3 and Comparative Examples 7 - 8 shows that the ultraviolet absorber consists of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531 in a mass ratio of 4:3. The ultraviolet absorber prevents the adhesive from degrading and discoloring due to ultraviolet irradiation. The synergistic effect of 2-hydroxy-4-n-octyloxybenzophenone and UV531 can not only effectively prevent discoloration caused by ultraviolet rays, but also enhance the overall weather resistance of the adhesive, extend its service life, and ensure its stability and aesthetics under various environmental conditions.

[0054] 5) Comparative analysis of the performance of the environmentally friendly anti-discoloration adhesives with stone adaptability prepared in Example 3 and Comparative Examples 9 - 10 shows that the modified tackifier consists of butyl epoxy oleate and modified lignin in a mass ratio of 3:2.5. By combining the tackifying effect of butyl epoxy oleate and the modification effect of modified lignin, the adhesive exhibits more excellent comprehensive performance in terms of bonding strength, water resistance, aging resistance, etc. Both butyl epoxy oleate and modified lignin are environmentally friendly materials that meet environmental protection requirements, and their combined action further improves the environmental performance of the adhesive.

[0055] The above embodiments are only used to explain and illustrate the technical solutions of the present application rather than to limit them. Although the above embodiments have specifically described the present application, those skilled in the art should understand that the specific implementation manners of the present application can still be modified or equivalently replaced. Any modification and equivalent replacement without departing from the spirit and scope of the present application shall be covered by the protection scope of the present application.

Claims

1. An environmentally friendly anti-discoloration adhesive with stone adaptability, characterized in that: The preparation raw materials include the following by weight: 90-100 parts of epoxy resin E-51, 25-30 parts of high temperature resistant and anti-discoloration polyurethane prepolymer, 10-12 parts of modified tackifier, 1-1.5 parts of composite coupling agent, 0.5-0.7 parts of antioxidant, 2-3 parts of ultraviolet absorber, 10-15 parts of calcium carbonate, 8-12 parts of diluent benzyl glycidyl ether and 7-10 parts of curing agent.

2. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 1, characterized in that: The preparation method of the high-temperature resistant and anti-discoloration polyurethane prepolymer comprises the following steps: adding 51 parts of diphenylmethane diisocyanate, 7.6 parts of ethyl isocyanate acrylate and 350 parts of N,N-dimethylformamide to a reaction kettle according to weight parts, and stirring evenly under nitrogen protection; then adding 32 parts of trans-3-hydroxypropylene boric acid pinacol ester, 33 parts of polyoxypropylene ether glycol and 7 parts of dibutyltin dilaurate, and reacting at 70-75°C for 120-150 minutes; then adding 0.2 parts of 4-allyl-2,6-di-tert-butylphenol, 4.5 parts of (ferrocenyl) hexanethiol and 8 parts of tripropylamine, and reacting at a temperature of 70-75°C for 60-70 minutes, and removing N,N-dimethylformamide by distillation to obtain the high-temperature resistant and anti-discoloration polyurethane prepolymer.

3. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 1, characterized in that: The modified tackifier is composed of epoxy butyl oleate and modified lignin in a mass ratio of 3:2-3.

4. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 3, characterized in that: The preparation method of the modified lignin comprises the following steps: S41, according to the mass fraction, adding 15 parts of lignin to 130 parts of formic acid, placing in a microwave reactor, reacting at 1000-1500W, 120-130°C for 40-50 minutes, then extracting with ethyl acetate 3 times, and rotary evaporating to obtain lignin oligomers; S42, adding 15 parts of lignin oligomers to 75 parts of N,N-dimethylformamide according to the mass fraction, and then adding 90 parts of 30wt% hydrobromic acid aqueous solution and 1 part of tetrabutylammonium bromide, reacting at 110-120°C for 20-24h, washing with water, and rotary evaporating to obtain demethylated lignin oligomers; S43. According to the mass proportions, under a nitrogen atmosphere, add 15 parts of demethylated lignin oligomers to 90 parts of N,N-dimethylformamide, then add 15 parts of 5-bromo-2-methylpentan-2-ol and 22 parts of sodium carbonate, react at 75-80° C. for 20-24 hours, wash with water, and rotary evaporate to obtain modified lignin.

5. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 1, characterized in that: The composite coupling agent is composed of gamma-aminopropyltriethoxysilane, vinyltriethoxysilane and gamma-ureapropyltrimethoxysilane in a mass ratio of 3:4:

3.

6. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 1, characterized in that: The antioxidant is composed of antioxidant 1010 and antioxidant 1076 in a mass ratio of 2:

3.

7. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 1, characterized in that: The ultraviolet absorber is composed of 2-hydroxy-4-n-octyloxybenzophenone and ultraviolet absorber UV531 in a mass ratio of 4:

3.

8. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 1, characterized in that: The preparation method of the curing agent is as follows: N-benzyldimethylamine, isophoronediamine and benzyl alcohol are mixed according to their mass fractions, the temperature is adjusted to 35-40° C., stirring is started, 1,4-butanediol diglycidyl ether is added dropwise, the addition is completed within 4 hours, the temperature is adjusted to 42-45° C., the reaction is continued for 80-90 minutes, and the curing agent is obtained by cooling to 30° C.

9. The environmentally friendly anti-discoloration adhesive with stone adaptability according to claim 8, characterized in that: The mass ratio of the N-benzyldimethylamine, isophoronediamine, benzyl alcohol and 1,4-butanediol diglycidyl ether is 4:2:4:

5.

10. A method for preparing an environmentally friendly anti-discoloration adhesive with stone adaptability as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: According to the mass proportions, epoxy resin E-51, high temperature resistant and anti-discoloration polyurethane prepolymer, modified tackifier, composite coupling agent, antioxidant, UV absorber, calcium carbonate and diluent benzyl glycidyl ether are put into the reactor, stirred at 70-75°C for 60-70 minutes, then cooled to 30°C and the curing agent is added and stirred for 10-15 minutes to obtain an environmentally friendly anti-discoloration adhesive with stone adaptability.

Images