A kind of light polyurethane coating and preparation method thereof

Abstract

The invention discloses a light polyurethane coating and a preparation method thereof, and belongs to the technical field of coating materials. The light polyurethane coating raw materials include: 30-40 parts of polyurethane resin, 15-25 parts of polyether polyol, 25-35 parts of acrylic resin, 10-15 parts of diphenylmethane diisocyanate, 15-20 parts of perlite, 5-10 parts of nano silicon dioxide, 1-2 parts of silane coupling agent, 2-5 parts of defoamer, 1-5 parts of plasticizer, 5-10 parts of auxiliary agent and 0.5-2 parts of catalyst. The auxiliary agent contains abundant hydroxyl groups, fluorine atoms and halogen-free flame retardant elements nitrogen, phosphorus and silicon, and there is a chemical reaction between the auxiliary agent and the polyurethane resin. Therefore, the auxiliary agent of the present invention can be highly dispersed and stably present in the polyurethane coating, and can give full play to its role, so that the light polyurethane coating of the present invention has excellent and stable hydrophobic and oleophobic properties and efficient and safe flame retardant effect.

Description

Technical Field

[0001] The invention belongs to the technical field of coating materials, and in particular relates to a lightweight polyurethane coating and a preparation method thereof. Background Art

[0002] Paint is a viscous liquid coated on the surface of the object to be protected or decorated, and can form a continuous film that is firmly attached to the object. It is usually mainly resin, oil, or emulsion, with or without pigments, fillers, and corresponding additives, and is prepared with organic solvents or water. Paint is often made of chemical mixtures and has four main functions: protection, decoration, concealing product defects and other special functions to enhance the value of the product.

[0003] Polyurethane coatings have become one of the fastest growing varieties in the global coatings industry in the past decade due to their excellent product performance and processing diversity. The average annual growth rate of polyurethane in foreign countries has reached twice the average growth rate of the coatings industry. With its superior physical and chemical properties, polyurethane coatings have been widely recognized and applied in the industry. Among polyurethane coatings, single-component polyurethane coatings are popular because of their convenient construction, especially for users who do not use much coatings such as home decoration, they do not need to consider weighing problems, and the unused coatings can be reused later. In addition, single-component polyurethane coatings also have excellent impact resistance and wear resistance.

[0004] However, for single-component polyurethane coatings, since the product after the polymerization reaction is organic matter, the coating itself has poor fire retardancy and is flammable, which does not meet the flame retardant requirements of building materials. At the same time, the existing single-component polyurethane coatings have poor flame retardancy, and the flame retardant effect is unstable, not durable, and unsafe. In addition, the hydrophobic and oleophobic properties of existing single-component polyurethane coatings need to be further improved. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a lightweight polyurethane coating and a preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A lightweight polyurethane coating comprises the following raw materials in parts by weight: 30-40 parts of polyurethane resin, 15-25 parts of polyether polyol, 25-35 parts of acrylic resin, 10-15 parts of diphenylmethane diisocyanate, 15-20 parts of perlite, 5-10 parts of nano silicon dioxide, 1-2 parts of silane coupling agent, 2-5 parts of defoamer, 1-5 parts of plasticizer, 5-10 parts of auxiliary agent and 0.5-2 parts of catalyst.

[0008] Furthermore, the polyether polyol is one or more of polyether polyol 210, polyether polyol 220, polyether polyol 330, and polyether polyol 330N.

[0009] Furthermore, the silane coupling agent is one or more of KH540, KH550, KH560, and KH570.

[0010] Perlite has the advantages of light apparent density, low thermal conductivity, good chemical stability and low moisture absorption capacity. Adding it to polyurethane coatings can give the coatings light weight, thermal insulation and other properties.

[0011] Silane coupling agent can reduce the surface energy of perlite and nano-silicon dioxide, so that the two can be highly dispersed in polyurethane coatings and give full play to their thermal insulation and heat preservation effects.

[0012] Furthermore, the defoaming agent is one or more of dimethyl silicone oil, polyether-modified silicone, and polyoxyethylene alcohol.

[0013] Furthermore, the plasticizer is one or more of dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, and chlorinated paraffin.

[0014] Furthermore, the auxiliary agent is prepared by the following steps:

[0015] S1. A dry brown three-necked flask was purged with nitrogen for 30 min, and then 1,3-propylenediamine, diethylphosphoacetic acid and DMSO (dimethyl sulfoxide) were added, and the mixture was stirred until completely dissolved, and then EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) were added, and the mixture was stirred and heated to 50°C for 6 h, and the mixture was distilled under reduced pressure to obtain intermediate 1; the dosage ratio of 1,3-propylenediamine, diethylphosphoacetic acid, EDC, NHS and DMSO was 7.2 mL: 12.9 mL: 0.46 g: 0.28 g: 120 mL;

[0016] The molar ratio of 1,3-propylenediamine to diethylphosphoacetic acid is controlled to be 1.05-1.1:1. Under the action of EDC and NHS, one -NH2 of 1,3-propylenediamine reacts with the -COOH of diethylphosphoacetic acid to undergo amidation reaction. The reaction equation is as follows:

[0017]

[0018] S2. Under nitrogen protection, 2-(perfluorohexyl)ethyl methacrylate, DBU (1,8-diazobispiro[5.4.0]undec-7-ene) and DMSO were added to a three-necked flask, stirred evenly, and then the mixed solution of intermediate 1 and DMSO was slowly added. After the addition was completed, the temperature was raised to 60°C and reacted for 48 hours. After the reaction was completed, the reaction was distilled under reduced pressure to obtain intermediate 2; the usage ratio of intermediate 1, 2-(perfluorohexyl)ethyl methacrylate, DBU and DMSO was 11 g:11.6 mL:1.4 mL:140 mL;

[0019] Under the catalytic action of DBU, the molar ratio of intermediate 1 to 2-(perfluorohexyl)ethyl methacrylate is controlled to be 1.05-1.1:1, and intermediate 1 and 2-(perfluorohexyl)ethyl methacrylate undergo Michael addition reaction. The reaction process is as follows:

[0020]

[0021] S3. Under nitrogen protection, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO were added to a dry three-necked flask. After stirring and dissolving, a mixed solution of intermediate 2 and DMSO was slowly added, and the temperature was raised to 80°C for reaction for 3 hours. After the reaction was completed, the mixture was cooled to room temperature and distilled under reduced pressure to obtain intermediate 3. The dosage ratio of intermediate 2, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO was 15.4 g:5.8 mL:4.8 mL:180 mL.

[0022] Under the action of triethylamine, the molar ratio of intermediate 2 to 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane is controlled to be 1:1.1-1.2, and the -NH- of intermediate 2 and a -Cl of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane undergo nucleophilic substitution reaction. The reaction process is as follows:

[0023]

[0024] S4. Add intermediate 3, triethylamine and DMF (N,N-dimethylformamide) to a dry three-necked flask under nitrogen protection, stir and dissolve, then slowly add 3-amino-1,2-propylene glycol, heat to 90°C and react for 5 hours after the addition is complete, cool to room temperature after the reaction is complete, and distill under reduced pressure to obtain an auxiliary agent. The dosage ratio of intermediate 3, 3-amino-1,2-propylene glycol, triethylamine and DMF is 46.9 g: 2 mL: 22.4 mL: 240 mL.

[0025] Under the action of triethylamine, the molar ratio of 3-amino-1,2-propylene glycol to intermediate 3 is controlled to be 1:2.05-2.1, and -Cl of intermediate 3 and -NH2 of 3-amino-1,2-propylene glycol undergo nucleophilic substitution reaction. The reaction process is as follows:

[0026]

[0027] The organic phosphorus in the auxiliary agent of the present invention decomposes to generate phosphorus oxygen acid, which can promote the formation of a carbon layer in the matrix. A large amount of carbon layer plays a role in blocking the flow of combustible gas and heat, thereby achieving a flame retardant effect; under the action of nitrogen, the carbon layer formed on the surface of the matrix will expand and foam to form a porous foam structure. The expanded porous foam carbon layer will further block the process of heat and oxygen exchange between the matrix and the outside world, further improving the flame retardant effect. At the same time, the flame retardant releases a large amount of non-combustible gas such as H2O, NH3, CO2, NO2, etc. during the combustion process, which can dilute the concentration of combustible gas and delay the spread of flames; silicon element generates an inorganic heat insulation protective layer containing -Si-O bond and -Si-C- bond during combustion, which not only prevents the decomposition products generated by combustion from escaping, but also inhibits the thermal decomposition of polymer materials, achieving the purpose of high flame retardancy, low smoke emission, and low harmfulness. The auxiliary agent of the present invention exerts an efficient and safe flame retardant effect through the synergistic effect of nitrogen, phosphorus, and silicon halogen-free flame retardant elements, and thus the polyurethane of the present invention has excellent flame retardancy.

[0028] Adding an auxiliary agent rich in fluorine atoms as a raw material into the polyurethane coating can significantly reduce the surface free energy of the polyurethane coating, so that the polyurethane coating of the present invention has excellent hydrophobicity and oleophobicity.

[0029] The additive contains abundant hydroxyl groups, which can react chemically with the unreacted isocyanate groups in the polyurethane resin under the action of a catalyst, so that the additive of the present invention can stably exist in the polyurethane coating, exerting an efficient, safe and long-lasting flame retardant effect and an excellent and stable hydrophobic and oleophobic effect.

[0030] Furthermore, the catalyst is one or more of an organic bismuth catalyst, an organic tin catalyst, and an inorganic tin catalyst.

[0031] A method for preparing a lightweight polyurethane coating comprises the following steps:

[0032] Weigh each raw material by weight, then heat the reactor to 80-100°C, add polyurethane resin, diphenylmethane diisocyanate, acrylic resin and polyether polyol while stirring; then slowly add nano-silica, perlite, coupling agent and catalyst, and continue stirring for 0.5-1h; wait for the reactor to cool to 45-60°C, add defoamer, plasticizer and additives, stir for 1-2h, then keep warm for 0.3-0.5h, and then cool to room temperature to obtain a lightweight polyurethane coating.

[0033] The beneficial effects of the present invention are as follows: the additive contains abundant hydroxyl groups, fluorine atoms and halogen-free flame retardant elements such as nitrogen, phosphorus and silicon, and there is a chemical reaction between the additive and the polyurethane resin. Therefore, the additive of the present invention can be highly dispersed and stably present in the polyurethane coating, and can fully play its role, so that the lightweight polyurethane coating of the present invention has excellent and stable hydrophobic and oleophobic properties and efficient and safe flame retardant effects; in addition, due to the combined effect of other raw materials, the coating of the present invention also has excellent thermal insulation properties. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] Preparation of auxiliary agent, the specific steps are as follows:

[0037] S1. A dry 250 mL brown three-necked flask was purged with nitrogen for 30 min, and then 7.2 mL of 1,3-propylenediamine, 12.9 mL of diethylphosphoacetic acid and 120 mL of DMSO were added and stirred until completely dissolved, followed by adding 0.46 g of EDC and 0.28 g of NHS, and the mixture was heated to 50 °C with continued stirring for 6 h, and then distilled under reduced pressure to obtain intermediate 1;

[0038] S2. Under nitrogen protection, 11.6 mL of 2-(perfluorohexyl)ethyl methacrylate, 1.4 mL of DBU, and 100 mL of DMSO were added to a 250 mL three-necked flask. After stirring, 11 g of a mixed solution of intermediate 1 and 40 mL of DMSO were slowly added. After the addition was completed, the temperature was raised to 60 ° C and the reaction was carried out for 48 hours. After the reaction was completed, the reaction was distilled under reduced pressure to obtain intermediate 2;

[0039] S3. Under nitrogen protection, add 5.8 mL of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, 4.8 mL of triethylamine and 40 mL of DMSO to a dry 500 mL three-necked flask. After stirring to dissolve, slowly add a mixed solution of 15.4 g of intermediate 2 and 140 mL of DMSO. Heat to 80 °C and react for 3 h. After the reaction is completed, cool to room temperature and distill under reduced pressure to obtain intermediate 3.

[0040] S4. Under nitrogen protection, add 46.9 g of intermediate 3, 22.4 mL of triethylamine and 240 mL of DMF into a dry 500 mL three-necked flask. After stirring to dissolve, slowly add 2 mL of 3-amino-1,2-propanediol. After the addition is completed, heat to 90 °C and react for 5 h. After the reaction is completed, cool to room temperature and distill under reduced pressure to obtain an auxiliary agent.

[0041] Example 2

[0042] The preparation of lightweight polyurethane coatings is carried out in the following steps:

[0043] Weigh each raw material by weight, then heat the reactor to 80°C, add 30 parts of polyurethane resin, 10 parts of diphenylmethane diisocyanate, 25 parts of acrylic resin and 15 parts of polyether polyol 210 while stirring; then slowly add 5 parts of nano-silicon dioxide, 15 parts of perlite, 1 part of silane coupling agent KH540 and 0.5 part of stannous oxide, and continue stirring for 0.5h; wait until the reactor is cooled to 45°C, add 2 parts of polyoxyethylene alcohol, 1 part of chlorinated paraffin and 5 parts of the auxiliary agent of Example 1, stir for 1h, then keep warm for 0.3h, and then cool to room temperature to obtain a lightweight polyurethane coating.

[0044] Example 3

[0045] The preparation of lightweight polyurethane coatings is carried out in the following steps:

[0046] Weigh each raw material by weight, then heat the reactor to 90°C, add 34 parts of polyurethane resin, 12 parts of diphenylmethane diisocyanate, 28 parts of acrylic resin and 18 parts of polyether polyol 220 while stirring; then slowly add 7 parts of nano-silicon dioxide, 17 parts of perlite, 1.5 parts of silane coupling agent KH550 and 1 part of dibutyltin dilaurate, and continue stirring for 0.8h; wait for the reactor to cool to 50°C, add 3 parts of polyether-modified silicone, 2 parts of dioctyl phthalate, 1 part of chlorinated paraffin and 7 parts of the additive of Example 1, stir for 1.5h, then keep warm for 0.4h, and then cool to room temperature to obtain a lightweight polyurethane coating.

[0047] Example 4

[0048] The preparation of lightweight polyurethane coatings is carried out in the following steps:

[0049] Weigh each raw material by weight, then heat the reactor to 100°C, add 40 parts of polyurethane resin, 15 parts of diphenylmethane diisocyanate, 35 parts of acrylic resin and 25 parts of polyether polyol 330 while stirring; then slowly add 10 parts of nano-silica, 20 parts of perlite, 2 parts of silane coupling agent KH560 and 2 parts of organic bismuth catalyst 8118, continue stirring for 1h; when the reaction kettle is cooled to 60°C, add 5 parts of dimethyl silicone oil, 3 parts of dibutyl phthalate, 2 parts of chlorinated paraffin and 10 parts of the additive of Example 1, stir for 2h, then keep warm for 0.5h, and then cool to room temperature to obtain a lightweight polyurethane coating.

[0050] Comparative Example 1

[0051] Preparation of polyurethane coating, the specific steps are as follows:

[0052] The remaining steps remain unchanged, and the auxiliary agent in Example 4 is removed to prepare the polyurethane coating.

[0053] Comparative Example 2

[0054] Preparation of polyurethane coating, the specific steps are as follows:

[0055] The remaining steps remain unchanged, and the auxiliary agent in Example 4 is replaced by the flame retardant FRC-6 to prepare the polyurethane coating.

[0056] Performance Testing

[0057] The surface of the substrate was cleaned and dried, and the polyurethane coatings prepared in Examples 2-4 and Comparative Examples 1-2 were applied on the surface of the substrate. After drying and curing, a coating film was obtained, and the following performance tests were performed:

[0058] The coating appearance test was carried out according to HGT3830-200 test standard 6; the contact angle of water and rapeseed oil on its surface was used to test the hydrophobic and oleophobic effect of the coating surface; the limiting oxygen index was determined according to GB / T2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test"; the coating adhesion was determined using GB / T9286-1998 "Scratching test of paint and varnish film";

[0059] The test results of all items are shown in the following table:

[0060]

[0061] It can be seen from the test results in the above table that the lightweight polyurethane coatings prepared in Examples 2-4 of the present invention have excellent hydrophobicity and oleophobicity and efficient and safe flame retardant effect.

[0062] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0063] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A lightweight polyurethane coating, characterized in that: The invention comprises the following raw materials in parts by weight: 30-40 parts of polyurethane resin, 15-25 parts of polyether polyol, 25-35 parts of acrylic resin, 10-15 parts of diphenylmethane diisocyanate, 15-20 parts of hollow glass microspheres, 5-10 parts of nano titanium dioxide, 1-2 parts of silane coupling agent, 2-5 parts of defoamer, 1-5 parts of plasticizer, 5-10 parts of auxiliary agent and 0.5-2 parts of catalyst; Wherein, the auxiliary agent is prepared by the following steps: S1, nitrogen purged flask, added 1,3-propylenediamine, diethylphosphoacetic acid and DMSO, stirred, added EDC and NHS, heated to 50°C for 6h, and distilled under reduced pressure to obtain intermediate 1; S2. Add 2-(perfluorohexyl)ethyl methacrylate and DMSO into a flask under nitrogen protection, add intermediate 1 and DMSO after stirring, react at 60° C. for 48 h, and distill under reduced pressure to obtain intermediate 2; S3. Add 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO to a flask under nitrogen protection, add intermediate 2 and DMSO after stirring, react at 80° C. for 3 h, cool, and distill under reduced pressure to obtain intermediate 3; S4. Add intermediate 3, triethylamine and DMF to a flask under nitrogen protection, add 3-amino-1,2-propanediol after stirring, react at 90° C. for 5 h, cool, and distill under reduced pressure to obtain an auxiliary agent. The molecular structure of the auxiliary agent is shown below:

2. A lightweight polyurethane coating according to claim 1, characterized in that: The usage ratio of 1,3-propylenediamine, diethylphosphoacetic acid, EDC, NHS and DMSO in step S1 is 7.2 mL:12.9 mL:0.46 g:0.28 g:120 mL.

3. A lightweight polyurethane coating according to claim 1, characterized in that: The usage ratio of the intermediate 1 in step S2, 2-(perfluorohexyl)ethyl methacrylate and DMSO is 11 g:11.6 mL:140 mL.

4. A lightweight polyurethane coating according to claim 1, characterized in that: The usage ratio of intermediate 2, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMSO in step S3 is 15.4 g:5.8 mL:4.8 mL:180 mL.

5. A lightweight polyurethane coating according to claim 1, characterized in that: The usage ratio of intermediate 3, 3-amino-1,2-propanediol, triethylamine and DMF in step S4 is 46.9 g: 2 mL: 22.4 mL: 240 mL.

6. A lightweight polyurethane coating according to claim 1, characterized in that: The polyether polyol is one or more of polyether polyol 210, polyether polyol 220, polyether polyol 330, and polyether polyol 330N.

7. A lightweight polyurethane coating according to claim 1, characterized in that: The silane coupling agent is one or more of KH540, KH550, KH560 and KH570.

8. A lightweight polyurethane coating according to claim 1, characterized in that: The defoamer is one or more of dimethyl silicone oil, polyether modified silicone, and polyoxyethylene alcohol; the plasticizer is one or more of dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, and chlorinated paraffin.

9. A lightweight polyurethane coating according to claim 1, characterized in that: The catalyst is one or more of an organic bismuth catalyst, an organic tin catalyst, and an inorganic tin catalyst.

10. The method for preparing a lightweight polyurethane coating according to claim 1, characterized in that: The following steps are involved: Weigh each raw material by weight, then heat the reactor to 80-100°C, add polyurethane resin, diphenylmethane diisocyanate, acrylic resin and polyether polyol while stirring; add nano titanium dioxide, hollow glass microspheres, coupling agent and catalyst, and stir for 0.5-1h; wait for the reactor to cool to 45-60°C, add defoamer, plasticizer and additives, stir for 1-2h, keep warm for 0.3-0.5h, and cool to room temperature to obtain a lightweight polyurethane coating.

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