UV coating with strong ultraviolet resistance and high wear resistance and preparation method thereof

Abstract

The invention relates to the field of photocureable coatings, in particular to a UV coating with strong ultraviolet resistance and high wear resistance and a preparation method thereof.The coating is prepared from UV gloss oil, a light stabilizer, a dispersing agent and a graphene modified polyurethane oligomer; the weight part ratio of the UV gloss oil to the graphene modified polyurethane oligomer is (80-120): (8-15); the graphene modified polyurethane oligomer is prepared from the following raw materials: polyether polyol, single-layer graphene oxide, polyisocyanate, a photocuring reaction monomer, a chain extender, a catalyst and a solvent; the carbon-oxygen ratio of the single-layer graphene oxide is less than or equal to 4; in the graphene modified polyurethane oligomer, graphene is interspersed in a polyurethane network and is connected with polyurethane through a covalent bond and a non-covalent bond; the coating disclosed by the invention has good ultraviolet resistance and wear resistance.

Description

Technical Field

[0001] The present invention relates to the field of photocurable coatings, and more specifically, to a highly ultraviolet-resistant and abrasion-resistant UV coating and a preparation method thereof. Background Art

[0002] UV-curing paints are widely used in interior building materials due to their fast curing rate, good surface properties, and controllable surface gloss. However, due to the large amount of photosensitive resins in UV-curing paint formulas, these resins often have poor UV tolerance and less than ideal abrasion resistance. Therefore, UV-curing paints have been difficult to apply to more demanding outdoor applications.

[0003] Graphene, a new type of two-dimensional carbon nanomaterial, possesses excellent optical, electrical, and mechanical properties, as well as good bioinhibition and chemical stability. In recent years, it has been widely used as a multifunctional material in the development of novel composite materials across various fields. Graphene can effectively enhance the mechanical properties of the matrix material while also effectively blocking and absorbing ultraviolet light, improving the matrix material's UV tolerance.

[0004] However, although graphene itself has excellent multiple functionalities, its relatively complex preparation process, high cost, and poor dispersibility and reactivity make it unsuitable for direct use as a functional additive in photocuring coating systems. Summary of the Invention

[0005] The present application provides a highly UV-resistant and wear-resistant UV coating and a preparation method thereof. By adding an appropriate amount of graphene-modified polyurethane oligomer to the UV coating system, the present application can evenly introduce graphene into the coating system, while further improving the wear resistance and UV resistance of the coating. The coating also has excellent adhesion and hardness and high curing efficiency.

[0006] In the first aspect, the present application provides a highly UV-resistant and wear-resistant UV coating, which adopts the following technical solution:

[0007] A highly ultraviolet-resistant and abrasion-resistant UV coating, comprising raw materials including UV varnish, a light stabilizer, a dispersant, and a graphene-modified polyurethane oligomer; the weight ratio of the UV varnish to the graphene-modified polyurethane oligomer is (80-120):(8-15); the graphene-modified polyurethane oligomer is made from raw materials including polyether polyol, single-layer graphene oxide, polyisocyanate, a photocurable reaction monomer, a chain extender, a catalyst, and a solvent; the carbon-oxygen ratio of the single-layer graphene oxide is ≤4; and in the graphene-modified polyurethane oligomer, graphene is interspersed in a polyurethane network and connected to the polyurethane via covalent bonds and non-covalent bonds.

[0008] By adopting the above technical solution, the present application adds a small amount of light stabilizer on the basis of ordinary UV varnish, improves the ultraviolet tolerance of the filler to a certain extent, and avoids excessive addition of light stabilizer to affect the curing efficiency of UV varnish. On this basis, a certain amount of dispersant is added to improve the dispersibility of graphene-modified polyurethane oligomer in UV varnish. The present application introduces graphene by introducing graphene-modified polyurethane oligomer. In the graphene-modified polyurethane oligomer of the present application, the monolayer graphene oxide with a carbon-oxygen ratio of ≤4 has high reaction activity and good dispersibility. The obtained oligomer graphene is interspersed in the polyurethane network, avoiding excessive graphene on the surface of the polyurethane, and can effectively reduce the problem of poor dispersibility of graphene in the coating system, so that the graphene-modified polyurethane oligomer can be fully and evenly dispersed in the coating system, thereby making full use of the mechanical properties and ultraviolet tolerance of graphene, and will not affect the curing and film formation of the coating itself. In addition, in the polyurethane network, graphene is connected to polyurethane through non-covalent bonds such as hydrogen bonds and covalent bonds such as ester bonds or ether bonds. Such a structure can further improve its dispersibility while reducing the problem of defects in the polyurethane cross-linked network caused by graphene agglomeration, which is beneficial to improving the overall comprehensive performance of the product.

[0009] In summary, the present application can not only smoothly introduce graphene components into the coating, effectively improve the dispersibility of graphene in UV coatings, and improve the UV resistance and wear resistance of the coating, but also will not affect the curing process and film-forming process of UV varnish.

[0010] Furthermore, the weight ratio of the UV varnish, the light stabilizer, and the dispersant is (80-120): (0.5-2): (1-3).

[0011] Furthermore, the dispersant is prepared by mixing 10% to 15wt% of fumed silica or titanium dioxide with ethyl acetate or isoamyl butyrate as a solvent.

[0012] Furthermore, the light stabilizer is Tinuvin 900, Tinuvin 400, or Tinuvin 292 from Ciba.

[0013] Furthermore, the preparation method of the graphene-modified polyurethane oligomer includes the following steps: uniformly stirring a polyether polyol, a single-layer graphene oxide and a chain extender at a temperature of 40 to 45°C; adding a polyisocyanate, raising the temperature to 55 to 60°C, and stirring for 5 to 10 minutes; then adding a catalyst, raising the temperature to 75 to 80°C, and stirring for a reaction of 2.5 to 3 hours; lowering the temperature to 55 to 60°C, dropwise adding a photocurable reaction monomer, continuing to stir for 3 to 5 hours, then lowering the temperature to 40 to 45°C, adding a solvent, and stirring for 0.5 to 1 hour to obtain the graphene-modified polyurethane oligomer.

[0014] Furthermore, the polyether polyol comprises at least one of pentaerythritol-propylene oxide polyether tetraol and pentaerythritol-ethylene oxide polyether tetraol. Furthermore, the molecular weight of the polyether polyol is 600-1000. Furthermore, the carbon-oxygen ratio of the monolayer graphene oxide is 3-4.

[0015] By adopting the above technical solution, the use of polyether polyols, such as pentaerythritol-propylene oxide polyether tetraol and pentaerythritol-ethylene oxide polyether tetraol, has multiple reactive groups, which can effectively improve the reaction conversion rate with graphene oxide, thereby improving the wear resistance and hardness of the coating substrate. Polyether polyols with a molecular weight of 600-1000 facilitate the mutual dispersion of polyether polyol and graphene oxide, making it easier for polyether polyol to penetrate into the interlayer structure of graphene oxide, improving reaction efficiency and making the resulting polymer network more stable. In addition, the use of polyether polyols with higher molecular weights is avoided, which reduces the problem of decreased coating hardness. Graphene oxide has an appropriate number of active functional groups and good reactivity, allowing it to fully react with other reactive monomers and further improve the strength and wear resistance of the coating.

[0016] Furthermore, the photocurable reaction monomer includes at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, and dipropylene glycol diacrylate.

[0017] Furthermore, the solvent includes at least one of ethyl acetate and isoamyl butyrate.

[0018] Furthermore, the chain extender includes at least one of 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutanoic acid or 2,3-dihydroxysuccinic acid.

[0019] Furthermore, the catalyst includes at least one of dibutyltin dilaurate, dibutyltin diacetate, and dimethyltin dimercaptoacetate.

[0020] In the second aspect, the present application provides a highly UV-resistant and wear-resistant UV coating, which adopts the following technical solution:

[0021] A method for preparing a highly ultraviolet-resistant and abrasion-resistant UV coating comprises the following steps: uniformly mixing a UV varnish and a light stabilizer; adding a dispersant thereto and mixing them uniformly; then adding a graphene-modified polyurethane oligomer thereto and mixing them uniformly; and finally raising the temperature of a reactor to 90-120° C. and mixing for 1-2 hours to obtain a finished UV coating.

[0022] In summary, this application has the following beneficial effects:

[0023] The UV coating applicable to outdoor building materials involved in the present application has strong ultraviolet tolerance and high wear resistance. By adding an appropriate amount of light stabilizer and graphene modified polyurethane oligomer, the ultraviolet tolerance of the coating as a whole is improved, and the wear resistance after solidification and film formation is effectively improved, which is very suitable for use on outdoor building materials surfaces. The UV coating applicable to outdoor building materials involved in the present application has strong ultraviolet tolerance and high wear resistance. By adding an appropriate amount of light stabilizer and graphene modified polyurethane oligomer, the ultraviolet tolerance of the coating as a whole is improved, and the wear resistance after solidification and film formation is effectively improved, which is very suitable for use on outdoor building materials surfaces. DETAILED DESCRIPTION

[0024] The present application is further described in detail below with reference to the embodiments.

[0025] The specific embodiment of the present application first provides a UV coating with strong UV resistance and high abrasion resistance, wherein the raw materials thereof include UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer. Specifically, the weight ratio of UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer is (80-120): (0.5-2): (1-3): (8-15).

[0026] The UV varnish is a conventional varnish, such as Zhanchen ZU52301, Clivia CAF-6021, or Hengxing J112-3. Zhanchen ZU52301 is used in this embodiment. Light stabilizers include Ciba's Tinuvin 900, Tinuvin 400, and Tinuvin 292. The dispersant is ethyl acetate or isoamyl butyrate as a solvent, mixed with 10% to 15% by weight of fumed silica or titanium dioxide.

[0027] The raw materials of the graphene-modified polyurethane oligomer include polyether polyol, single-layer graphene oxide, polyisocyanate, photocuring reaction monomer, chain extender, catalyst and solvent in a weight ratio of (20-30): (1-2): (10-15): (5-10): (60-80): (0.5-1): (120-150).

[0028] Among the above raw materials, the polyether polyol includes at least one of pentaerythritol-propylene oxide polyether tetraol and pentaerythritol-ethylene oxide polyether tetraol, and the molecular weight of the polyether polyol is 600-1000.

[0029] The carbon-oxygen ratio of the monolayer graphene oxide is 3 to 4, where the carbon-oxygen ratio is the ratio of element content (atomic fraction). The polyisocyanate includes at least one of HDI trimer, IPDI, and H12MDI. The photocurable reaction monomer includes at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, and dipropylene glycol diacrylate. The chain extender includes at least one of 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid, or 2,3-dihydroxysuccinic acid. The catalyst includes at least one of dibutyltin dilaurate, dibutyltin diacetate, and dimethyltin dimercaptoacetate. The solvent includes at least one of ethyl acetate and isoamyl butyrate.

[0030] The preparation method of the graphene-modified polyurethane oligomer comprises the following steps:

[0031] The polyether polyol, monolayer graphene oxide and chain extender are stirred uniformly at a temperature of 40-45°C; polyisocyanate is added, the temperature is raised to 55-60°C, and stirred for 5-10 minutes; then a catalyst is added, the temperature is raised to 75-80°C, and the reaction is stirred for 2.5-3 hours; the temperature is lowered to 55-60°C, a photocurable reaction monomer is added dropwise, and stirring is continued for 3-5 hours, then the temperature is lowered to 40-45°C, a solvent is added, and stirring is continued for 0.5-1 hour to obtain a graphene-modified polyurethane oligomer.

[0032] The embodiment of the present application discloses a preparation method of a UV coating with strong ultraviolet resistance and high wear resistance, comprising the following steps: adding UV varnish and light stabilizer to a reactor at a temperature of 30-35°C and mixing them uniformly at a speed of 850-1000 r / min; then adding a dispersant thereto, keeping the speed unchanged, and mixing for 5-10 minutes; then adding graphene-modified polyurethane oligomer thereto, increasing the speed to 1400-1600 r / min, and mixing for 0.5-1 hour; finally, increasing the temperature of the reactor to 90-120°C, maintaining a slight negative pressure in the reactor, keeping the speed unchanged, and mixing for 1-2 hours, to finally obtain a finished UV coating.

[0033] The following is an explanation through specific preparation examples and examples.

[0034] Preparation example of graphene-modified polyurethane oligomer

[0035] Preparation Example 1

[0036] This preparation example provides a graphene-modified polyurethane oligomer, the raw materials of which include polyether polyol, monolayer graphene oxide, polyisocyanate, photocurable reaction monomer, chain extender, catalyst and solvent in a weight ratio of 26:1.5:13:6:60:0.5:120.

[0037] Among the above raw materials, the polyether polyol is a pentaerythritol-propylene oxide polyether tetraol with a molecular weight of 800. The carbon-oxygen ratio of the monolayer graphene oxide is 3.5. The polyisocyanate is HDI trimer; the photocurable monomer is hydroxyethyl methacrylate; the chain extender is 2,2-dihydroxymethylpropionic acid (DMPA); the catalyst is dibutyltin dilaurate; and the solvent is ethyl acetate.

[0038] This preparation example also provides a method for preparing a graphene-modified polyurethane oligomer, comprising the following steps:

[0039] The polyether polyol, monolayer graphene oxide and chain extender were stirred evenly at 45°C; polyisocyanate was added, the temperature was raised to 58°C, and stirred for 8 minutes; then a catalyst was added, the temperature was raised to 78°C, and the reaction was stirred for 2.8 hours; the temperature was lowered to 56°C, a photocurable reaction monomer was added dropwise, and stirring was continued for 4 hours, then the temperature was lowered to 43°C, a solvent was added, and stirring was continued for 0.6 hours to obtain a graphene-modified polyurethane oligomer.

[0040] Preparation Example 2

[0041] This preparation example first provides a graphene-modified polyurethane oligomer, whose raw materials include polyether polyol, single-layer graphene oxide, polyisocyanate, photocuring reaction monomer, chain extender, catalyst and solvent in a weight ratio of 20:1:15:5:78:0.8:130.

[0042] Among the above raw materials, the polyether polyol is a pentaerythritol-propylene oxide polyether tetraol with a molecular weight of 600. The carbon-oxygen ratio of the monolayer graphene oxide is 4. The polyisocyanate is IPDI, and the photocurable monomer is hydroxyethyl methacrylate. The chain extender includes 2,2-dimethylolpropionic acid (DMPA). The catalyst is dibutyltin dilaurate. The solvent is isoamyl butyrate.

[0043] This preparation example also provides a method for preparing a graphene-modified polyurethane oligomer, comprising the following steps:

[0044] The polyether polyol, monolayer graphene oxide and chain extender were stirred evenly at 40°C; polyisocyanate was added, the temperature was raised to 60°C, and stirred for 5 minutes; then a catalyst was added, the temperature was raised to 75°C, and the reaction was stirred for 3 hours; the temperature was lowered to 55°C, a photocurable reaction monomer was added dropwise, and the stirring was continued for 5 hours, then the temperature was lowered to 40°C, a solvent was added, and the reaction was stirred for 0.5 hours to obtain a graphene-modified polyurethane oligomer.

[0045] Preparation Example 3

[0046] This preparation example first provides a graphene-modified polyurethane oligomer, whose raw materials include polyether polyol, single-layer graphene oxide, polyisocyanate, photocuring reaction monomer, chain extender, catalyst and solvent in a weight ratio of 30:2:10:10:80:1:150.

[0047] Among the above raw materials, the polyether polyol is a pentaerythritol-ethylene oxide polyether tetraol with a molecular weight of 600. The carbon-to-oxygen ratio of the monolayer graphene oxide is 3. The polyisocyanate is H12MDI, and the photocurable monomer is hydroxyethyl acrylate. The chain extender is 2,2-dihydroxymethylbutyric acid. The catalyst is dibutyltin diacetate. The solvent is ethyl acetate.

[0048] This preparation example also provides a method for preparing a graphene-modified polyurethane oligomer, comprising the following steps:

[0049] The polyether polyol, monolayer graphene oxide and chain extender were stirred evenly at 43°C; polyisocyanate was added, the temperature was raised to 56°C, and stirred for 10 minutes; then a catalyst was added, the temperature was raised to 75°C, and the reaction was stirred for 2.5 hours; the temperature was lowered to 55°C, a photocurable reaction monomer was added dropwise, and the stirring was continued for 5 hours, then the temperature was lowered to 45°C, a solvent was added, and the mixture was stirred for 1 hour to obtain a graphene-modified polyurethane oligomer.

[0050] Preparation Example 4

[0051] This preparation example first provides a graphene-modified polyurethane oligomer, whose raw materials include polyether polyol, single-layer graphene oxide, polyisocyanate, photocuring reaction monomer, chain extender, catalyst and solvent in a weight ratio of 28:1.3:14:8:77:0.7:130.

[0052] Among the above raw materials, the polyether polyol is a pentaerythritol-propylene oxide polyether tetraol with a molecular weight of 1000. The carbon-oxygen ratio of the monolayer graphene oxide is 4. The polyisocyanate is HDI trimer, and the photocurable monomer is dipropylene glycol diacrylate. The chain extender includes 2,2-dihydroxymethylpropionic acid (DMPA). The catalyst is dimethyltin dimercaptoacetate. The solvent is isoamyl butyrate.

[0053] This preparation example also provides a method for preparing a graphene-modified polyurethane oligomer, comprising the following steps:

[0054] Stir polyether polyol, monolayer graphene oxide, and chain extender at 42°C until uniformly mixed. Add polyisocyanate, raise the temperature to 59°C, and stir for 10 minutes. Then add catalyst, raise the temperature to 76°C, and stir for 2.6 hours. Lower the temperature to 57°C, add photocurable monomer dropwise, and continue stirring for 3.5 hours. Then, cool to 42°C, add solvent, and stir for 0.8 hour to obtain graphene-modified polyurethane oligomer.

[0055] UV coating examples

[0056] Example 1

[0057] This embodiment provides a UV coating with strong UV resistance and high abrasion resistance, wherein the raw materials include UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer in a weight ratio of 100:2:3:10. The graphene-modified polyurethane oligomer is obtained from Preparation Example 1.

[0058] The light stabilizer is Tinuvin 900. The dispersant is ethyl acetate as solvent mixed with 12% fumed silica.

[0059] The preparation method of the above-mentioned strong UV-resistant and highly wear-resistant UV coating includes the following steps: adding UV varnish and light stabilizer into a reactor at a temperature of 33°C and mixing them evenly at a speed of 900 r / min; then adding a dispersant thereto, keeping the speed unchanged and mixing for 6 minutes; then adding graphene-modified polyurethane oligomer thereto, increasing the speed to 1500 r / min, and mixing for 0.8 hours; finally, increasing the temperature of the reactor to 100°C, maintaining a slight negative pressure in the reactor, keeping the speed unchanged, and mixing for 1.5 hours to finally obtain the finished UV coating.

[0060] Example 2

[0061] This embodiment provides a UV coating with strong UV resistance and high abrasion resistance, wherein the raw materials include UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer in a weight ratio of 120:0.5:1:15. The graphene-modified polyurethane oligomer is obtained from Preparation Example 2.

[0062] The light stabilizer is Tinuvin 400. The dispersant is isoamyl butyrate as solvent mixed with 10% fumed titanium dioxide.

[0063] The preparation method of the above-mentioned strong UV-resistant and highly wear-resistant UV coating includes the following steps: adding UV varnish and light stabilizer into a reactor at a temperature of 30°C and mixing them evenly at a speed of 1000 r / min; then adding a dispersant thereto, keeping the speed unchanged and mixing for 5 minutes; then adding graphene-modified polyurethane oligomer thereto, increasing the speed to 1600 r / min and mixing for 1 hour; finally, increasing the temperature of the reactor to 90°C, maintaining a slight negative pressure in the reactor, keeping the speed unchanged, mixing for 1 hour, and finally obtaining a finished UV coating.

[0064] Example 3

[0065] This embodiment provides a UV coating with strong UV resistance and high abrasion resistance, wherein the raw materials include UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer in a weight ratio of 80:1:1:8. The graphene-modified polyurethane oligomer is obtained from Preparation Example 3.

[0066] The light stabilizer is Tinuvin 292. The dispersant is ethyl acetate as solvent mixed with 13% fumed silica.

[0067] The preparation method of the above-mentioned strong UV-resistant and highly wear-resistant UV coating includes the following steps: adding UV varnish and light stabilizer into a reactor at a temperature of 30°C and mixing them evenly at a speed of 850 r / min; then adding a dispersant thereto, keeping the speed unchanged and mixing for 10 minutes; then adding graphene-modified polyurethane oligomer thereto, increasing the speed to 1450 r / min and mixing for 1 hour; finally, increasing the temperature of the reactor to 120°C, maintaining a slight negative pressure in the reactor, keeping the speed unchanged, mixing for 1 hour, and finally obtaining a finished UV coating.

[0068] Example 4

[0069] This embodiment provides a UV coating with strong UV resistance and high abrasion resistance, wherein the raw materials include UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer in a weight ratio of 110:1.6:1.8:13. The graphene-modified polyurethane oligomer is obtained from Preparation Example 4.

[0070] The light stabilizer is Tinuvin 292. The dispersant is isoamyl butyrate as solvent mixed with 12% fumed titanium dioxide.

[0071] The preparation method of the above-mentioned strong UV-resistant and highly wear-resistant UV coating includes the following steps: adding UV varnish and light stabilizer into a reactor at a temperature of 32°C and mixing them evenly at a speed of 950 r / min; then adding a dispersant thereto, keeping the speed unchanged and mixing for 8 minutes; then adding graphene-modified polyurethane oligomer thereto, increasing the speed to 1600 r / min, and mixing for 0.9 hours; finally, increasing the temperature of the reactor to 110°C, maintaining a slight negative pressure in the reactor, keeping the speed unchanged, and mixing for 1 hour to finally obtain the finished UV coating.

[0072] Comparative Example

[0073] Comparative Example 1

[0074] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0075] Step 1: Add ethyl acetate to a 1% monolayer graphene oxide dispersion (carbon-oxygen ratio 3.5) and stir for 0.6 h to obtain a monolayer graphene oxide dispersion.

[0076] Step 2: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 90 into the reactor, set the temperature at 33°C, and mix them evenly at a speed of 900 r / min.

[0077] Step 3: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0078] Step 4: add 10 parts of the single-layer graphene oxide dispersion obtained in step 1, increase the speed to 1500 r / min, and mix for 0.8 h.

[0079] Step 5: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0080] Comparative Example 2

[0081] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0082] Step 1: 26 parts of pentaerythritol-propylene oxide polyether tetraol (molecular weight 800), 1.5 parts of monolayer graphene oxide (carbon-oxygen ratio 3.5), and 66 parts of DMPA were stirred at 45°C.

[0083] Step 2: Add 13 parts of polyisocyanate HDI trimer, raise the temperature to 58°C, and stir for 8 minutes;

[0084] Step 3: Add 0.6 parts of dibutyltin dilaurate, raise the temperature to 78°C, and stir to react for 2.8 hours;

[0085] Step 4: The temperature was lowered to 56°C, 6 parts of hydroxyethyl methacrylate were added dropwise, and stirring was continued for 4 hours;

[0086] Step 5: The temperature was lowered to 43° C., and then 120 parts of ethyl acetate was added and stirred for 0.6 h to obtain a graphene-modified polyurethane oligomer.

[0087] Step 6: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 900 into the reactor, set the temperature to 33°C, and mix them evenly at a speed of 900 r / min.

[0088] Step 7: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0089] Step 8: Add 20 parts of the graphene-modified polyurethane oligomer obtained in step 5, increase the speed to 1500 r / min, and mix for 0.8 h.

[0090] Step 9: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0091] Comparative Example 3

[0092] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0093] Step 1: 26 parts of pentaerythritol-propylene oxide polyether tetraol (molecular weight 800), 1.5 parts of graphite oxide, and 66 parts of DMPA were stirred at 45°C.

[0094] Step 2: Add 13 parts of polyisocyanate HDI trimer, raise the temperature to 58°C, and stir for 8 minutes;

[0095] Step 3: Add 0.6 parts of dibutyltin dilaurate, raise the temperature to 78°C, and stir to react for 2.8 hours;

[0096] Step 4: The temperature was lowered to 56°C, 6 parts of hydroxyethyl methacrylate were added dropwise, and stirring was continued for 4 hours;

[0097] Step 5: The temperature was lowered to 43° C., and then 120 parts of ethyl acetate were added and stirred for 0.6 h to obtain a graphite-modified polyurethane active functional oligomer.

[0098] Step 6: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 900 into the reactor, set the temperature to 33°C, and mix them evenly at a speed of 900 r / min.

[0099] Step 7: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0100] Step 8: Add 10 parts of the graphite-modified polyurethane active functional oligomer obtained in step 5, increase the speed to 1500 r / min, and mix for 0.8 h.

[0101] Step 9: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0102] Comparative Example 4

[0103] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0104] Step 1: 26 parts of pentaerythritol-propylene oxide polyether tetraol (molecular weight 800), 1.5 parts of monolayer graphene oxide (carbon-oxygen ratio 5.5), and 66 parts of DMPA were stirred at 45°C.

[0105] Step 2: Add 13 parts of polyisocyanate HDI trimer, raise the temperature to 58°C, and stir for 8 minutes;

[0106] Step 3: Add 0.6 parts of dibutyltin dilaurate, raise the temperature to 78°C, and stir to react for 2.8 hours;

[0107] Step 4: The temperature was lowered to 56°C, 6 parts of hydroxyethyl methacrylate were added dropwise, and stirring was continued for 4 hours;

[0108] Step 5: The temperature was lowered to 43° C., and then 120 parts of ethyl acetate was added and stirred for 0.6 h to obtain a graphene-modified polyurethane oligomer.

[0109] Step 6: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 900 into the reactor, set the temperature to 33°C, and mix them evenly at a speed of 900 r / min.

[0110] Step 7: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0111] Step 8: Add 10 parts of the graphene-modified polyurethane oligomer obtained in step 5, increase the speed to 1500 r / min, and mix for 0.8 h.

[0112] Step 9: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0113] Comparative Example 5

[0114] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0115] Step 1: 26 parts of pentaerythritol-propylene oxide polyether tetraol (molecular weight 800), 1.5 parts of monolayer graphene oxide (carbon-oxygen ratio 2), and 66 parts of DMPA were stirred at 45°C.

[0116] Step 2: Add 13 parts of polyisocyanate HDI trimer, raise the temperature to 58°C, and stir for 8 minutes;

[0117] Step 3: Add 0.6 parts of dibutyltin dilaurate, raise the temperature to 78°C, and stir to react for 2.8 hours;

[0118] Step 4: The temperature was lowered to 56°C, 6 parts of hydroxyethyl methacrylate were added dropwise, and stirring was continued for 4 hours;

[0119] Step 5: The temperature was lowered to 43° C., and then 120 parts of ethyl acetate was added and stirred for 0.6 h to obtain a graphene-modified polyurethane oligomer.

[0120] Step 6: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 900 into the reactor, set the temperature to 33°C, and mix them evenly at a speed of 900 r / min.

[0121] Step 7: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0122] Step 8: Add 10 parts of the graphene-modified polyurethane oligomer obtained in step 5, increase the speed to 1500 r / min, and mix for 0.8 h.

[0123] Step 9: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0124] Comparative Example 6

[0125] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0126] Step 1: 26 parts of pentaerythritol-propylene oxide polyether tetraol (molecular weight 3000), 1.5 parts of monolayer graphene oxide (carbon-oxygen ratio 3.5), and 66 parts of DMPA were stirred at 45°C.

[0127] Step 2: Add 13 parts of polyisocyanate HDI trimer, raise the temperature to 58°C, and stir for 8 minutes;

[0128] Step 3: Add 0.6 parts of dibutyltin dilaurate, raise the temperature to 78°C, and stir to react for 2.8 hours;

[0129] Step 4: The temperature was lowered to 56°C, 6 parts of hydroxyethyl methacrylate were added dropwise, and stirring was continued for 4 hours;

[0130] Step 5: The temperature was lowered to 43° C., and then 120 parts of ethyl acetate was added and stirred for 0.6 h to obtain a graphene-modified polyurethane oligomer.

[0131] Step 6: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 900 into the reactor, set the temperature to 33°C, and mix them evenly at a speed of 900 r / min.

[0132] Step 7: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0133] Step 8: Add 10 parts of the graphene-modified polyurethane oligomer obtained in step 5, increase the speed to 1500 r / min, and mix for 0.8 h.

[0134] Step 9: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0135] Comparative Example 7

[0136] A method for preparing a graphene-modified polyurethane oligomer and a method for preparing a coating, comprising the following steps:

[0137] Step 1: 26 parts of ethylene oxide polyether diol (molecular weight 600), 1.5 parts of monolayer graphene oxide (carbon-oxygen ratio 3.5), and 66 parts of DMPA were stirred at 45°C.

[0138] Step 2: Add 13 parts of polyisocyanate, raise the temperature to 58°C, and stir for 8 minutes;

[0139] Step 3: Add 0.6 parts of dibutyltin dilaurate, raise the temperature to 78°C, and stir to react for 2.8 hours;

[0140] Step 4: The temperature was lowered to 56°C, 6 parts of hydroxyethyl methacrylate were added dropwise, and stirring was continued for 4 hours;

[0141] Step 5: The temperature is lowered to 43° C., and then 120 parts of ethyl acetate or isoamyl butyrate are added and stirred for 0.6 h to obtain a graphene-modified polyurethane oligomer.

[0142] Step 6: Add 100 parts of UV varnish and 1 part of light stabilizer Tinuvin 900 into the reactor, set the temperature to 33°C, and mix them evenly at a speed of 900 r / min.

[0143] Step 7: Add 2 parts of dispersant and mix for 6 minutes at the same speed. The dispersant is made of ethyl acetate as solvent and 12% fumed silica.

[0144] Step 8: Add 10 parts of the graphene-modified polyurethane oligomer obtained in step 5, increase the speed to 1500 r / min, and mix for 0.8 h.

[0145] Step 9: Raise the temperature of the reactor to 100°C, maintain a slight negative pressure in the reactor, keep the speed unchanged, mix for 1.5 hours, and finally obtain the finished UV coating.

[0146] Comparative Example 8

[0147] A graphene-modified polyurethane oligomer, whose raw materials include polyether polyol, single-layer graphene oxide, polyisocyanate, photocuring reaction monomer, chain extender, catalyst and solvent in a weight ratio of 26:1.5:13:6:60:0.5:120.

[0148] Among the above raw materials, the polyether polyol is a pentaerythritol-propylene oxide polyether tetraol with a molecular weight of 800. The carbon-oxygen ratio of the monolayer graphene oxide is 3.5. The polyisocyanate is HDI trimer. The photocurable monomer is hydroxyethyl methacrylate. The chain extender includes 2,2-dihydroxymethylpropionic acid (DMPA). The catalyst is dibutyltin dilaurate. The solvent is ethyl acetate.

[0149] A method for preparing a graphene-modified polyurethane oligomer comprises the following steps:

[0150] The polyether polyol, polyisocyanate and chain extender were stirred evenly at 45°C; a single layer of graphene oxide was added, the temperature was raised to 58°C, and the mixture was stirred for 8 minutes; a catalyst was then added, the temperature was raised to 78°C, and the mixture was stirred for 2.8 hours; the temperature was lowered to 56°C, a photocurable reaction monomer was added dropwise, and the mixture was stirred for 4 hours, then the temperature was lowered to 43°C, a solvent was added, and the mixture was stirred for 0.6 hours to obtain a graphene-modified polyurethane oligomer.

[0151] This comparative example also provides a highly UV-resistant and wear-resistant UV coating, the raw materials of which include UV varnish, light stabilizer, dispersant, and graphene-modified polyurethane oligomer in a weight ratio of 100:1:2:10.

[0152] The light stabilizer is Tinuvin 900. The dispersant is ethyl acetate as solvent mixed with 12% fumed silica.

[0153] The preparation method of the above-mentioned strong UV-resistant and highly wear-resistant UV coating includes the following steps: adding UV varnish and light stabilizer into a reactor at a temperature of 33°C and mixing them evenly at a speed of 900 r / min; then adding a dispersant thereto, keeping the speed unchanged and mixing for 6 minutes; then adding graphene-modified polyurethane oligomer thereto, increasing the speed to 1500 r / min, and mixing for 0.8 hours; finally, increasing the temperature of the reactor to 100°C, maintaining a slight negative pressure in the reactor, keeping the speed unchanged, and mixing for 1.5 hours to finally obtain the finished UV coating.

[0154] Comparative Example 9: Conventional UV varnish Zhanchen ZU52301.

[0155] Performance testing

[0156] For the coatings obtained from the application examples and comparative examples, relevant performance tests were carried out. The specific operations are as follows:

[0157] The coating was applied to the wood flooring substrate using a roller coating method with a coating thickness of 20 μm. A curing lamp using a mercury-gallonian lamp was used for a curing time of 30 seconds. The resulting samples were subjected to a 1000-h UV aging test to test their yellowing resistance (GB / T 23983-2009). The surface abrasion resistance (1000 g / 500 r) was also tested (GB / T 1768-2006), the film hardness was tested (pencil hardness GB / T 6739-2022), and the film adhesion was tested (cross-cut method ISO 2409-2024). The test results are shown in Table 1.

[0158] Table 1 Performance test table of embodiments and comparative examples

[0159] Detection object Yellowing resistance △E Wear resistance Curing efficiency Paint film hardness Adhesion Application Example 1 1.29 0.008 normal 4H Level 0 Application Example 2 1.26 0.007 normal 4H Level 0 Application Example 3 1.18 0.008 normal 4H Level 0 Application Example 4 1.23 0.006 normal 4H Level 0 Comparative Example 1 4.45 0.026 normal 2H Level 1 Comparative Example 2 3.86 0.089 Incomplete curing / / Comparative Example 3 4.32 0.028 normal 2H Level 3 Comparative Example 4 4.23 0.024 normal 2H Level 3 Comparative Example 5 1.56 0.019 normal 3H Level 0 Comparative Example 6 1.66 0.018 normal 1H Level 0 Comparative Example 7 1.68 0.022 normal 2H Level 0 Comparative Example 8 3.70 0.029 normal 2H Level 0 Comparative Example 9 5.28 0.023 normal 1H Level 0

[0160] First, by comparing and analyzing the performance of Examples 1 to 4 and Comparative Example 9, it can be seen that after the graphene-modified polyurethane oligomer prepared in the present application is added to the UV coating, the wear resistance, hardness and UV resistance of the coating can be effectively improved without affecting the curing efficiency and film formation of the coating.

[0161] Further, the performance discovery of analysis comparative example 1, directly after graphene oxide is added in coating, although the curing efficiency of coating has no influence, the UV resistance, wear resistance and hardness, adhesive force of coating have decline to varying degrees.This explanation why the performance of the coating of the present application is well improved is because what is added is the graphene-modified polyurethane oligomer prepared by the present application, and the graphene-modified polyurethane oligomer as a whole improves the various properties of coating. For the graphene-modified polyurethane oligomer of the present application, while it smoothly enters graphene in the coating system, it also effectively improves the dispersibility of graphene in the system, and forms the structure that graphene is interspersed in the polyurethane network, and then makes graphene give full play to its UV resistance in coating, and oligomer effectively improves the comprehensive performance of coating. In addition, in conjunction with the performance discovery of comparative example 2, the consumption of graphene-modified polyurethane oligomer in coating should not be too much, otherwise it can affect the solidification of coating, and UV resistance and wear resistance also decline significantly.

[0162] Regarding the preparation of graphene-modified polyurethane oligomers, we first analyzed Comparative Examples 3-7. In Comparative Example 3, graphite oxide was used instead of monolayer graphene oxide. In Comparative Examples 4 and 5, the carbon-to-oxygen ratios of the monolayer graphene oxide were too high and too low, respectively. In Comparative Example 6, the molecular weight of the polyether polyol used was too high. In Comparative Example 7, ethylene oxide polyether diol (molecular weight 600) was used as the polyether polyol. Observation of the performance of Comparative Examples 3-7 revealed varying degrees of decline in various coating properties, with Comparative Examples 3 and 4 exhibiting the most severe performance declines. This demonstrates that, in graphene-modified polyurethane oligomers, the raw material system used in their preparation plays a crucial role in the final product performance, with the excessively high carbon-to-oxygen ratio of graphene oxide and the use of graphene oxide having a significant impact on the oligomer. In the technical solution of the present application, monolayer graphene oxide and polyether polyol have good reactivity and high reaction efficiency, and the two can be dispersed with each other, so that graphene is interspersed in the polyurethane network and connected to the polyurethane through non-covalent bonds such as hydrogen bonds and covalent bonds such as ester bonds or ether bonds, thereby greatly improving the comprehensive performance of the coating.

[0163] Further, analysis of the performance of Comparative Example 8 revealed that, in the preparation steps for the graphene-modified polyurethane oligomer in Comparative Example 8, the polyether polyol, polyisocyanate and chain extender were first reacted, and then a single-layer graphene oxide was added. The yellowing resistance and wear resistance of Comparative Example 8 decreased to a certain extent compared with the examples, and the hardness of the paint film also decreased. This is because in the technical solution of the present application, the single-layer graphene oxide was reacted with the polyether polyol and the chain extender in advance, so that the graphene was interspersed in the polyurethane network to obtain an oligomer with excellent performance. However, during the reaction process of Comparative Example 8, the graphene could not be well interspersed in the polyurethane network, and the coating performance could not be well improved.

[0164] Therefore, in the preparation process of the oligomer of the present application, its raw material system is very important. In addition, appropriate reaction steps enable the present application to form a structure in which graphene is interspersed in the polyurethane network, which can greatly improve the performance of the coating.

[0165] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A highly UV-resistant and wear-resistant UV coating, characterized in that: The raw materials include UV varnish, a light stabilizer, a dispersant, and a graphene-modified polyurethane oligomer; the weight ratio of the UV varnish to the graphene-modified polyurethane oligomer is (80-120):(8-15); the graphene-modified polyurethane oligomer is made from raw materials including polyether polyol, single-layer graphene oxide, polyisocyanate, a photocuring reaction monomer, a chain extender, a catalyst, and a solvent; the carbon-oxygen ratio of the single-layer graphene oxide is ≤4; in the graphene-modified polyurethane oligomer, graphene is interspersed in a polyurethane network and connected to the polyurethane through covalent bonds and non-covalent bonds.

2. A strong ultraviolet-resistant and highly wear-resistant UV coating according to claim 1, characterized in that: The weight ratio of the UV varnish, the light stabilizer and the dispersant is (80-120): (0.5-2): (1-3).

3. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The dispersant is prepared by mixing 10% to 15wt% of fumed silica or titanium dioxide with ethyl acetate or isoamyl butyrate as a solvent.

4. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The light stabilizers are Tinuvin 900, Tinuvin 400 and Tinuvin 292 from Ciba.

5. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The preparation method of the graphene-modified polyurethane oligomer comprises the following steps: uniformly stirring a polyether polyol, a single-layer graphene oxide and a chain extender at a temperature of 40-45° C.; adding a polyisocyanate, raising the temperature to 55-60° C., and stirring for 5-10 minutes; then adding a catalyst, raising the temperature to 75-80° C., and stirring for reaction for 2.5-3 hours; lowering the temperature to 55-60° C., dropwise adding a photocurable reaction monomer, continuing stirring for 3-5 hours, then lowering the temperature to 40-45° C., adding a solvent, and stirring for 0.5-1 hour to obtain the graphene-modified polyurethane oligomer.

6. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The polyether polyol includes at least one of pentaerythritol-propylene oxide polyether tetraol and pentaerythritol-ethylene oxide polyether tetraol; and the molecular weight of the polyether polyol is 600-1000.

7. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The carbon-oxygen ratio of the single-layer graphene oxide is 3-4.

8. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The photocurable reaction monomer includes at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, and dipropylene glycol diacrylate.

9. The UV coating with strong ultraviolet resistance and high wear resistance according to claim 1, characterized in that: The solvent includes at least one of ethyl acetate and isoamyl butyrate; the chain extender includes at least one of 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid or 2,3-dihydroxysuccinic acid.

10. A method for preparing a highly ultraviolet-resistant and wear-resistant UV coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: The UV varnish and the light stabilizer are mixed evenly; a dispersant is added thereto and mixed evenly; then the graphene-modified polyurethane oligomer is added thereto and mixed evenly; finally, the temperature of the reactor is increased to 90-120° C. and mixed for 1-2 hours to finally obtain a finished UV coating.