Low-carbon environmentally friendly functionalized graphene oxide polyurethane coating and preparation method thereof

Abstract

The present invention discloses a low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating and a preparation method thereof, and belongs to the technical field of coatings. The present invention aims at the problem that graphene oxide has poor compatibility with coating matrix resins such as epoxy resin in the prior art. The present invention performs composite modification on graphene oxide by using a silane coupling agent and a titanate coupling agent, thereby improving the compatibility of graphene oxide with other substances, thereby effectively improving the dispersion performance of graphene oxide. On this basis, the graphene oxide is further functionalized by using a titanate coupling agent, and the titanate coupling agent and the silane coupling agent are entangled in long chains. The impact strength, elongation and shear strength of the long-chain entangled graphene oxide can be effectively improved. At the same time, the silane coupling agent can make the titanate coupling agent evenly combined with the graphene oxide surface, so that the titanate coupling agent can be more evenly dispersed in the coating, thereby better improving the heat resistance of the coating.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating and a preparation method thereof. Background Art

[0002] The main components of polyurethane coatings include polyols and isocyanates, and polyols and isocyanates are cross-linked and cured to obtain polyurethane coatings. The polyols in traditional polyurethane coatings generally come from the petrochemical industry. With the increasing reduction of petrochemical resources, the price of polyols in traditional polyurethane coatings continues to rise. Therefore, the development of polyurethane coatings with bio-based polyols as raw materials has become a current research hotspot. However, bio-based polyurethanes have disadvantages such as poor high temperature resistance, poor flame retardancy and poor mechanical properties. When bio-based polyurethane coatings are used as paint film protective layers for outdoor equipment, they are eroded by acid rain, oil stains and other solvents for a long time, and are prone to damage and other phenomena, losing their protective effect. Therefore, in order to enable bio-based polyurethane coatings to provide long-term protection for outdoor equipment, the performance of bio-based polyurethane coatings needs to be improved.

[0003] Graphene is an effective reinforcing filler for preparing composite coatings due to its large specific surface area, specific layered structure, high mechanical strength and good thermal stability. However, the strong van der Waals interaction between graphene sheets makes it easy to re-stack and agglomerate in the polymer matrix, which directly affects the performance of the composite coating. Graphene oxide has a planar structure similar to graphene and contains a large number of active groups (such as carboxyl, hydroxyl, etc.) on the surface. Compared with graphene, graphene oxide has better dispersibility and reactivity, but because the hydroxyl and carboxyl groups on the surface of GO are hydrophilic groups, there is a problem of poor compatibility with coating matrix resins such as epoxy resin. Summary of the invention

[0004] In view of the problems in the prior art, the present invention provides a low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating and a preparation method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A low-carbon and environment-friendly functionalized graphene oxide polyurethane coating comprises component A and component B, wherein component A comprises the following raw materials: composite functionalized graphene oxide, bio-based polyol, petroleum-based polyol and additives, wherein the mass ratio of the composite functionalized graphene oxide, bio-based polyol and petroleum-based polyol is 0.1-1:100-300:100-300, the composite functionalized graphene oxide is obtained by functionalizing graphene oxide with a silane coupling agent and a titanate coupling agent, and component B comprises isocyanate and component B additives.

[0007] A method for preparing a low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating comprises the following steps:

[0008] Step A: preparing composite functionalized graphene oxide;

[0009] Step B: preparing bio-based polyols;

[0010] Step C: mixing the petroleum-based polyol, the composite functionalized graphene oxide prepared in step A, the bio-based polyol prepared in step B, and the additives in proportion to obtain component A;

[0011] Step D: Component B and component A obtained in step C are mixed uniformly according to a certain proportion to obtain a polyurethane coating.

[0012] Furthermore, the specific steps of preparing the composite functionalized graphene oxide in step A are as follows:

[0013] Step A1: preparing amino-functionalized graphene oxide by using a silane coupling agent and graphene oxide;

[0014] Step A2: preparing composite functionalized graphene oxide by using a titanate coupling agent and amino-functionalized graphene oxide.

[0015] Furthermore, the silane coupling agent is one or more of 3-methoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-hydroxyethyl)propyltrimethoxysilane or γ-aminopropyltriethoxysilane.

[0016] Furthermore, the titanate coupling agent is one or more of chelate coupling agents, and the chelate coupling agent includes bis(dioctyl pyrophosphate)hydroxyacetate titanate and bis(dioctyloxypyrophosphate)ethylene titanate.

[0017] Furthermore, the specific steps of step A1 are:

[0018] Step A101: 1-3 g of graphene oxide was added to 200 ml of dimethylformamide for ultrasonic dispersion;

[0019] Step A102: After the ultrasonic dispersion is completed, 1-10 g of a silane coupling agent is added dropwise to the system, and stirred at a temperature of 50-100° C. for 1-5 h to obtain a mixed solution containing amino-functionalized graphene oxide.

[0020] Furthermore, the specific steps of step A2 are:

[0021] Step A201: 1-10 g of a titanate coupling agent is added dropwise to the mixed solution containing amino-functionalized graphene oxide obtained in step A102, and stirred at a temperature of 50-120° C. for 1-3 h to obtain a mixed solution containing composite functionalized graphene oxide;

[0022] Step A202: filtering the mixed solution containing the composite functionalized graphene oxide, and washing the filter residue;

[0023] Step A203: Dry the washed filter residue to obtain composite functionalized graphene oxide.

[0024] Furthermore, the auxiliary agent of component A includes a chain extender, and the ratio of the composite functionalized graphene oxide, bio-based polyol, petroleum-based polyol, and chain extender is 0.1-1:100-300:100-300:1-20.

[0025] Furthermore, the specific steps of step B are:

[0026] Step B1: premix ethylene glycol, diethanolamine and potassium acetate according to a certain proportion to prepare a mixed solution;

[0027] Step B2: Add the recovered vegetable oil and the mixed solution obtained in step B1 into a reactor in proportion, and stir continuously at a temperature of 100-400° C. for 30-180 minutes to obtain bio-based polyols. During this process, nitrogen flows in the reactor and the vacuum pressure is 400-800 MPa.

[0028] Furthermore, the recovered vegetable oil is soybean oil, peanut oil, palm oil, rapeseed oil, jatropha oil or Pistacia chinensis oil or a combination of two or more thereof.

[0029] Furthermore, the isocyanate is toluene diisocyanate, xylene diisocyanate, polymerized diphenylmethane diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate.

[0030] Furthermore, the petroleum-based polyol can be a polyether polyol or a polyester polyol, among which acetylene-containing polyol is preferred. Because the polyurethane coating prepared from petroleum-based polyol has better heat resistance and mechanical properties than bio-based polyol, and acetylene-containing polyol has higher thermal stability, it can be used to make up for the defects of bio-based polyol in coatings.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] 1. The present invention uses a silane coupling agent and a titanate coupling agent to functionalize graphene to obtain a composite functionalized graphene oxide, and the composite functionalized graphene oxide is used to modify the plant oil-based polyurethane coating to make it more environmentally friendly and have better physical and chemical properties.

[0033] 2. The present invention performs composite modification on graphene oxide by using a silane coupling agent and a titanate coupling agent. After modification by using a silane coupling agent, the surface of graphene oxide has more groups that can be combined with other substances, thereby improving the compatibility of graphene oxide with other substances, thereby effectively improving the dispersion performance of graphene oxide. On this basis, the graphene oxide is further functionalized by using a titanate coupling agent, and the titanate coupling agent and the silane coupling agent are entangled in long chains. The impact strength, elongation and shear strength of the long-chain entangled graphene oxide can be effectively improved. Therefore, the composite modified graphene oxide not only has better dispersibility, but also the silane coupling agent can make the titanate coupling agent evenly combined with various parts of the graphene oxide surface. When the graphene oxide is dispersed in the coating, the titanate coupling agent can also be more evenly dispersed in the coating, thereby better improving the heat resistance of the coating. The composite modification of graphene oxide using silane coupling agent and titanate coupling agent and the functionalization of graphene oxide can not only improve the dispersibility of graphene oxide in polyurethane coatings, but also improve the overall performance of polyurethane coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0036] Example 1

[0037] like Figure 1 As shown, a low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating comprises component A and component B, wherein component A comprises the following raw materials: composite functionalized graphene oxide, bio-based polyol, petroleum-based polyol and additives, wherein the addition amounts of the composite functionalized graphene oxide, bio-based polyol and petroleum-based polyol are 0.6 g, 250 g and 250 g respectively, and the additives comprise 0.3 g of chain extender dimethylolbutyric acid (DMBA), 0.3 g of dispersant Disponer 9250, 0.3 g of dispersant Efka4015, 0.1 g of anti-sagging agent Byk 410, and 0.5 g of defoamer Efka 2723, wherein the composite functionalized graphene oxide is obtained by functionalizing graphene oxide with aminopropyltrimethoxysilane and chelated titanate coupling agent TC-WT in sequence, wherein component B consists of toluene diisocyanate and a film-forming agent, and the mass ratio of component A to component B is 2:1.

[0038] A method for preparing a low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating comprises the following steps:

[0039] Step A: preparing composite functionalized graphene oxide;

[0040] Step A1: preparing amino-functionalized graphene oxide by using a silane coupling agent and graphene oxide;

[0041] Step A101: adding 2 g of graphene oxide into 200 ml of dimethylformamide for ultrasonic dispersion;

[0042] Step A102: After the ultrasonic dispersion is completed, 5 g of aminopropyltrimethoxysilane is added dropwise to the system, and stirred at 80° C. for 3 h to obtain a mixed solution containing amino-functionalized graphene oxide;

[0043] Step A2: preparing composite functionalized graphene oxide by using a titanate coupling agent and amino-functionalized graphene oxide;

[0044] Step A201: add 6 g of chelated titanate coupling agent TC-WT to the mixed solution containing amino-functionalized graphene oxide obtained in step A102, and stir at 100° C. for 3 h to obtain a mixed solution containing composite functionalized graphene oxide;

[0045] Step A202: filtering the mixed solution containing the composite functionalized graphene oxide, and washing the filter residue;

[0046] Step A203: drying the washed filter residue to obtain composite functionalized graphene oxide;

[0047] Step B: preparing bio-based polyols;

[0048] Step B1: pre-mix ethylene glycol, diethanolamine and potassium acetate in a ratio of 30:3:1 to prepare a mixed solution;

[0049] Step B2: adding the recovered vegetable oil and the mixed solution obtained in step B1 into a reactor at a ratio of 20:80, and continuously stirring at a temperature of 300° C. for 150 minutes to obtain bio-based polyols, during which nitrogen flows in the reactor and the vacuum pressure is 600 MPa;

[0050] Step C: 25g of propylene oxide ether polyol, 600mg of the composite functionalized graphene oxide prepared in step A, 25g of the bio-based polyol prepared in step B, 0.3g of chain extender dimethylolbutyric acid (DMBA), 0.3g of dispersant Disponer 9250, 0.3g of dispersant Efka 4015, 0.1g of anti-sagging agent Byk 410, and 0.5g of defoamer Efka 2723 are added to a container, and the disperser is turned on to stir (1000-1200 r / min) for 30 min, and then the mixed solution after mixing evenly is transferred to a reactor with a vacuum function, the temperature is raised to 100 ° C, the vacuum device is turned on to remove water for 1 h, the vacuum device is turned off, and the material is cooled to room temperature and canned, and marked as component A;

[0051] Step D: Component A and component B obtained in step C are mixed evenly in a ratio of 2:1 to obtain a polyurethane coating, and the polyurethane coating is applied on the surface of the substrate to form a film.

[0052] Example 2

[0053] This embodiment is basically the same as Embodiment 1, except that the amount of titanate coupling agent added in step A201 of Embodiment 2 is 1 g.

[0054] Example 3

[0055] This embodiment is basically the same as Embodiment 1, except that the amount of titanate coupling agent added in step A201 of Embodiment 3 is 10 g.

[0056] Example 4

[0057] This embodiment is basically the same as Embodiment 1, except that the amount of composite functionalized graphene oxide added in step C of Embodiment 4 is 100 mg.

[0058] Example 5

[0059] This embodiment is basically the same as Embodiment 1, except that the amount of composite functionalized graphene oxide added in step C of Embodiment 5 is 1 g.

[0060] Comparative Example 1

[0061] This comparative example is substantially the same as Example 1, except that no composite functionalized graphene oxide is added in Comparative Example 1.

[0062] Comparative Example 2

[0063] This comparative example is basically the same as Example 1, except that the graphene oxide added in Comparative Example 2 is a single modified graphene oxide, and its specific preparation method is:

[0064] 2 g of graphene oxide was added to 200 ml of dimethylformamide for ultrasonic dispersion;

[0065] After the ultrasonic dispersion was completed, 5 g of aminopropyltrimethoxysilane was added dropwise to the system and stirred at 80° C. for 3 h to obtain a mixed solution containing amino-functionalized graphene oxide;

[0066] filtering the mixed solution containing amino-functionalized graphene oxide, and washing the filter residue;

[0067] The washed filter residue is dried to obtain single modified graphene oxide.

[0068] Comparative Example 3

[0069] This comparative example is basically the same as Example 1, except that the graphene oxide added in Comparative Example 3 is a single modified graphene oxide, and its specific preparation method is:

[0070] 2 g of graphene oxide was added to 200 ml of dimethylformamide for ultrasonic dispersion;

[0071] After the ultrasonic dispersion was completed, 6 g of chelated titanate coupling agent TC-WT was added dropwise to the system and stirred at 100° C. for 3 h to obtain a mixed solution containing a single modified graphene oxide.

[0072] filtering the mixed solution containing the single modified graphene oxide, and washing the filter residue;

[0073] The washed filter residue is dried to obtain single modified graphene oxide.

[0074] Comparative Example 4

[0075] This comparative example is basically the same as Example 1, except that in this comparative example, the chelate titanate coupling agent TC-WT is first used to modify the graphene oxide, specifically:

[0076] Step A101: 2 g of graphene oxide was added to 200 ml of dimethylformamide for ultrasonic dispersion;

[0077] Step A102: After the ultrasonic dispersion is completed, 6 g of chelate titanate coupling agent TC-WT is added dropwise to the system and stirred at 100° C. for 3 h;

[0078] Step A201: 5 g of aminopropyltrimethoxysilane was added dropwise to the mixed solution obtained in step A102, and stirred at 80° C. for 3 h to obtain a mixed solution containing composite functionalized graphene oxide;

[0079] Step A202: filtering the mixed solution containing the composite functionalized graphene oxide, and washing the filter residue;

[0080] Step A203: drying the washed filter residue to obtain composite functionalized graphene oxide;

[0081] Comparative Example 5

[0082] This comparative example is basically the same as Example 1, except that in this comparative example, aminopropyltrimethoxysilane and chelate titanate coupling agent TC-WT are added simultaneously to improve graphene oxide, specifically:

[0083] Step A101: 2 g of graphene oxide was added to 200 ml of dimethylformamide for ultrasonic dispersion;

[0084] Step A102: After the ultrasonic dispersion is completed, 6 g of chelate titanate coupling agent TC-WT and 5 g of aminopropyltrimethoxysilane are added dropwise to the system, and stirred at 100° C. for 6 h;

[0085] Step A202: filtering the mixed solution containing the composite functionalized graphene oxide, and washing the filter residue;

[0086] Step A203: drying the washed filter residue to obtain composite functionalized graphene oxide;

[0087] Comparative Example 6

[0088] This comparative example is basically the same as Example 1, except that this comparative example does not contain 25 g of petroleum-based propylene oxide ether polyol, and the added amount of the bio-based polyol prepared in step B is 50 g.

[0089] Comparative Example 7

[0090] This comparative example is basically the same as Example 1, except that this comparative example does not contain the bio-based polyol prepared in step B, but adds 50 g of petroleum-based propylene oxide ether polyol.

[0091] The mechanical properties test and the conventional properties test of the coating were carried out on Examples 1-5 and Comparative Examples 1-7, wherein the mechanical properties test results are shown in Table 1, and the conventional properties test results of the coating are shown in Table 2:

[0092] Table 1

[0093] Sample No. Tensile strength at break (MPa) Tearing elongation (%) Example 1 4.081 614.902 Example 2 3.628 583.981 Example 3 3.938 609.712 Example 4 3.595 579.712 Example 5 3.965 613.872 Comparative Example 1 3.102 511.324 Comparative Example 2 3.392 564.871 Comparative Example 3 3.476 572.993 Comparative Example 4 3.884 589.548 Comparative Example 5 3.969 585.562 Comparative Example 6 3.572 487.326 Comparative Example 7 4.643 665.831

[0094] Table 2

[0095] Test project name Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Coating color Gray black Gray black Gray black Gray black Gray black transparent Gray black Coating appearance smooth smooth smooth smooth smooth smooth smooth hardness 3H 2H 3H H 3H H 2H Adhesion (pulled surface / carbon steel) MPa 4.6 4.5 4.5 4.3 4.6 4.1 4.3 Surface drying time / min ≤20 ≤20 ≤20 ≤20 ≤20 ≤30 ≤30 Drying time / h ＜12 ＜12 ＜12 ＜12 ＜12 ＜12 ＜12 Heat resistance No abnormality No abnormality No abnormality No abnormality No abnormality Yellowing Slightly discolored Coating temperature change resistance (5 cycles) No abnormality No abnormality No abnormality No abnormality No abnormality Yellowing Slightly discolored

[0096] Table 3

[0097] Test project name Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Coating color Gray black Gray black Gray black Gray black Gray black Coating appearance smooth smooth smooth smooth smooth hardness 2H 3H 3H H 3H Adhesion (pulled surface / carbon steel) MPa 4.2 4.5 4.4 4.3 4.6 Surface drying time / min ≤30 ≤20 ≤20 ≤40 ≤20 Drying time / h ＜12 ＜12 ＜12 ＜18 ＜12 Heat resistance No abnormality No abnormality No abnormality No abnormality No abnormality Coating temperature change resistance (5 cycles) No abnormality No abnormality No abnormality No abnormality No abnormality

[0098] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating, characterized in that: The method comprises component A and component B, wherein component A comprises the following raw materials: Composite functionalized graphene oxide, bio-based polyol, petroleum-based polyol and additives, wherein the mass ratio of the composite functionalized graphene oxide, bio-based polyol and petroleum-based polyol is 0.1-1:100-300:100-300, the composite functionalized graphene oxide is obtained by functionalizing graphene oxide with a silane coupling agent and a titanate coupling agent, and the component B comprises isocyanate; The silane coupling agent is one or more of 3-methoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-hydroxyethyl)propyltrimethoxysilane or γ-aminopropyltriethoxysilane; The titanate coupling agent is one or more chelate coupling agents; The preparation steps of composite functionalized graphene oxide are as follows: Step A1: preparing amino-functionalized graphene oxide by using a silane coupling agent and graphene oxide; Step A2: preparing composite functionalized graphene oxide by using a titanate coupling agent and amino-functionalized graphene oxide; The preparation steps of bio-based polyols are: Step B1: pre-mix ethylene glycol, diethanolamine and potassium acetate in a ratio of 20-50:1-5:1-5 to prepare a mixed solution; Step B2: Add the recovered vegetable oil and the mixed solution obtained in step B1 into a reactor at a ratio of 20-50:80-50, and stir continuously at a temperature of 100-400° C. for 30-180 minutes to obtain bio-based polyols. During the process, nitrogen flows in the reactor and the vacuum pressure is 400-800 MPa.

2. A method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 1, characterized in that: The following steps are involved: Step A: preparing composite functionalized graphene oxide; Step B: preparing bio-based polyols; Step C: mixing the petroleum-based polyol, the composite functionalized graphene oxide prepared in step A, the bio-based polyol prepared in step B, and the additives in proportion to obtain component A; Step D: Component A obtained in step C is mixed evenly with component B in a mass ratio of 2:1 to obtain a polyurethane coating.

3. The method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 2, characterized in that: The specific steps of preparing composite functionalized graphene oxide in step A are as follows: Step A1: preparing amino-functionalized graphene oxide by using a silane coupling agent and graphene oxide; Step A2: preparing composite functionalized graphene oxide by using a titanate coupling agent and amino-functionalized graphene oxide.

4. The method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 2, characterized in that: The specific steps of step A1 are: Step A101: 1-3 g of graphene oxide was added to 200 ml of dimethylformamide for ultrasonic dispersion; Step A102: After the ultrasonic dispersion is completed, 1-10 g of a silane coupling agent is added dropwise to the system, and stirred at a temperature of 50-100° C. for 1-5 h to obtain a mixed solution containing amino-functionalized graphene oxide; The specific steps of step A2 are: Step A201: 1-10 g of a titanate coupling agent is added dropwise to the mixed solution containing amino-functionalized graphene oxide obtained in step A102, and stirred at a temperature of 50-120° C. for 1-3 h to obtain a mixed solution containing composite functionalized graphene oxide; Step A202: filtering the mixed solution containing the composite functionalized graphene oxide, and washing the filter residue; Step A203: Dry the washed filter residue to obtain composite functionalized graphene oxide.

5. The method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 2, characterized in that: The auxiliary agent of component A includes a chain extender, and the ratio of the composite functionalized graphene oxide, bio-based polyol, petroleum-based polyol and chain extender is 0.1-1:100-300:100-300:1-20.

6. The method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 5, characterized in that: The chain extender is one or more of ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, and glycerol.

7. The method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 2, characterized in that: The specific steps of step B are: Step B1: pre-mix ethylene glycol, diethanolamine and potassium acetate in a ratio of 20-50:1-5:1-5 to prepare a mixed solution; Step B2: Add the recovered vegetable oil and the mixed solution obtained in step B1 into a reactor at a ratio of 20-50:80-50, and stir continuously at a temperature of 100-400° C. for 30-180 minutes to obtain bio-based polyols. During the process, nitrogen flows in the reactor and the vacuum pressure is 400-800 MPa.

8. The method for preparing the low-carbon and environmentally friendly functionalized graphene oxide polyurethane coating according to claim 2, characterized in that: The isocyanate is toluene diisocyanate, xylene diisocyanate, polymerized diphenylmethane diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate.

Images