Water-based environment-friendly coating and preparation method thereof

Abstract

The invention discloses a water-based environment-friendly coating and a preparation method thereof, and the water-based environment-friendly coating is prepared from the following raw materials in parts by weight: 100 to 120 parts of polyurethane emulsion, 0.05 to 0.1 part of defoaming agent, 1.5 to 3 parts of dispersing agent, 15 to 20 parts of modified filler, 3 to 5 parts of 1-hydroxycyclohexyl phenyl ketone, 20 to 30 parts of methyl methacrylate and 10 to 20 parts of water, the surface of the modified filler contains a long-chain organic silicon chain segment, so that a paint film can form a hydrophobic film after being dried, the existence of a silicon dioxide matrix can prevent water from being in direct contact with a polyurethane molecular chain segment, so that the water-resistant effect of the paint film is further improved, the modified monomer is of a hyperbranched structure, and the molecular chain contains the organic silicon chain segment, so that the water resistance of the paint film is improved. Meanwhile, long-chain olefin of a side chain can be grafted with double bonds on methyl methacrylate and the modified filler when being irradiated by ultraviolet light, so that a new cross-linking site is formed on the surface of a paint film, the compactness of the hydrophobic film is increased, and the water-resistant effect is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of water-based coating preparation, and in particular to a water-based environmentally friendly coating and a preparation method thereof. Background Art

[0002] With the continuous enhancement of environmental awareness, traditional solvent-based coatings are facing unprecedented challenges due to their large volatile organic compound emissions and serious environmental pollution. As an environmentally friendly coating that can replace solvent-based coatings, water-based coatings have developed rapidly in recent years. Its advantages such as low VOC emissions, fast drying speed, and safe operation have made it widely used in many fields such as construction, furniture, and automobiles. At present, the widely used water-based coatings in the market include water-based inorganic zinc-rich coatings, water-based epoxy coatings, water-based acrylic coatings, etc. Conventional water-based coatings have poor water resistance. After being soaked in water for a period of time, bubbles and shedding will occur, making the coating unable to function during use. Summary of the invention

[0003] The purpose of the present invention is to provide a water-based environmentally friendly coating and a preparation method thereof, which solves the problems of poor water resistance and poor adhesion of the current water-based environmentally friendly coating.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing a water-based environmentally friendly coating comprises the following steps:

[0006] Step A1: adding poly(1,4-butylene adipate diol) into a reaction kettle, introducing nitrogen protection, stirring and adding isophorone diisocyanate at a speed of 120-150 r / min and a temperature of 70-80° C., reacting for 30-40 min, adding 2,2-dihydroxymethylpropionic acid, reacting for 1-1.5 h, adding a modified monomer and butanediol, reacting for 1-1.5 h, adding triethylamine, reacting for 1-1.5 h, adding deionized water, stirring for 2-3 h at a speed of 500-600 r / min and a temperature of 25-30° C., to obtain a polyurethane emulsion;

[0007] Step A2: Weigh the following raw materials in parts by weight: 100-120 parts of polyurethane emulsion, 0.05-0.1 parts of defoaming agent, 1.5-3 parts of dispersant, 15-20 parts of modified filler, 3-5 parts of 1-hydroxycyclohexyl phenyl ketone, 20-30 parts of methyl methacrylate and 10-20 parts of water, and mix the raw materials evenly to obtain a water-based environmentally friendly coating.

[0008] Furthermore, the dosage ratio of the poly(1,4-butylene adipate) diol, isophorone diisocyanate, 2,2-dihydroxymethylpropionic acid, modified monomer, butanediol, triethylamine and deionized water in step A1 is 12mmo l:23mmo l:1mmol:1.5mmo l:8mmo l:1mmo l:200mL, and the molecular weight of the poly(1,4-butylene adipate) diol is 2000.

[0009] Further, the modified monomer is prepared by the following steps:

[0010] Step B1: octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and dimethyl sulfoxide are mixed uniformly, nitrogen is introduced for protection, and the reaction is carried out for 3-5 hours at a speed of 120-150 r / min and a temperature of 90-95° C. to obtain a diamine-terminated polysiloxane; oleyl alcohol, epichlorohydrin, boron trifluoride etherate and DMF are mixed uniformly, and the reaction is carried out for 2-3 hours at a speed of 120-150 r / min and a temperature of 65-70° C.; sodium hydroxide solution is added, the temperature is raised to 75-80° C., and the reaction is carried out for 3-5 hours to obtain a modifier;

[0011] Step B2: Evenly mix the diamine-terminated polysiloxane, the modifier and DMF, and react for 3-5 hours at a rotation speed of 150-200 r / min, a temperature of 40-50°C and a pH value of 11-12 to obtain a modified polysiloxane; evenly mix the modified polysiloxane, 3,4-dihydroxystyrene, chloroplatinic acid and DMF, and react for 6-8 hours at a rotation speed of 120-150 r / min and a temperature of 70-80°C to obtain a modified monomer.

[0012] Further, the amount ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane described in step B1 is 2:0.4:3:2, the amount ratio of oleyl alcohol, epichlorohydrin, boron trifluoride etherate and sodium hydroxide solution is 30 mmol:30 mmol:0.9 g:20 mL, and the mass fraction of the sodium hydroxide solution is 25%.

[0013] Furthermore, the molar ratio of the diamine-terminated polysiloxane and the modifier in step B2 is 1:4, the molar ratio of the SiH bond on the modified polysiloxane and 3,4-dihydroxystyrene is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 3,4-dihydroxystyrene.

[0014] Further, the modified filler is prepared by the following steps:

[0015] Step C1: L-arginine and deionized water are mixed evenly, and ethyl orthosilicate is added under the conditions of a rotation speed of 500-600 r / min and a temperature of 20-25° C., and the temperature is raised to 80-85° C., and the reaction is carried out for 20-25 hours to obtain hydroxy nano-silicon dioxide, and the hydroxy nano-silicon dioxide is dispersed in ethanol, and KH550 is added under the conditions of a rotation speed of 150-200 r / min and a temperature of 70-80° C., and the reaction is carried out for 3-5 hours to obtain pretreated silica;

[0016] Step C2: n-butyl lithium, n-hexane and benzene are uniformly mixed, argon gas is introduced to remove air, hexamethylcyclotrisiloxane is added under stirring at a speed of 60-80 r / min and a temperature of 20-25° C., stirring for 30-40 min, tetrahydrofuran is added, and the mixture is reacted for 7-9 h, dimethylchlorosilane is added, and the mixture is reacted for 30-40 min to obtain monohydrogenpolysiloxane;

[0017] Step C3: uniformly mix monohydrogen polysiloxane, allyl alcohol glycidyl ether, chloroplatinic acid and DMF, and react for 3-5 hours at a rotation speed of 120-150 r / min and a temperature of 70-80°C to obtain a treating agent; uniformly mix the pretreated silica, the treating agent and DMF, and react for 4-6 hours at a rotation speed of 200-300 r / min, a temperature of 40-50°C and a pH value of 11-12 to obtain modified silica; and mix the modified silica, potassium carbonate and DMF, and stir and add vinyl chloride at a rotation speed of 150-200 r / min and a temperature of 100-110°C to obtain a modified filler.

[0018] Furthermore, the dosage ratio of L-arginine, deionized water and tetraethyl orthosilicate in step C1 is 1 mmol:150 mL:100 mmol, and the dosage of KH550 is 1% of the mass of hydroxy nano-silica.

[0019] Furthermore, the dosage ratio of n-butyl lithium, n-hexane, benzene, hexamethylcyclotrisiloxane, tetrahydrofuran and dimethylchlorosilane in step C2 is 7.5 g: 20 mL: 10 mL: 500 mmol: 30 mL: 25 mmol.

[0020] Furthermore, the molar ratio of monohydrogenpolysiloxane and allyl alcohol glycidyl ether described in step C3 is 1:1, the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol glycidyl ether, and the amount ratio of modified silica, potassium carbonate, DMF and vinyl chloride is 1g:3g:20mL:1.5g.

[0021] Beneficial effects of the present invention: A water-based environmentally friendly coating prepared by the present invention comprises the following raw materials: polyurethane emulsion, defoaming agent, dispersant, modified filler, 1-hydroxycyclohexyl phenyl ketone, methyl methacrylate and water. The polyurethane emulsion is reacted with poly(1,4-butylene adipate) diol and isophorone diisocyanate, and then reacted with 2,2-dihydroxymethylpropionic acid, modified monomer and butanediol in sequence, and finally neutralized with triethylamine to obtain the polyurethane emulsion.

[0022] The modified monomer is ring-opened with octamethylcyclotetrasiloxane and tetramethylcyclotetrasiloxane as raw materials, and then polymerized with 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane to obtain diamine-terminated polysiloxane, oleyl alcohol is reacted with epichlorohydrin so that the hydroxyl group on the oleyl alcohol reacts with the epoxy group on the epichlorohydrin, and then the ring is closed under the action of sodium hydroxide solution to obtain a modifier, the diamine-terminated polysiloxane is reacted with the modifier so that the amino group on the diamine-terminated polysiloxane reacts with the epoxy group on the modifier to obtain a modified polysiloxane, and the modified polysiloxane is reacted with 3,4-dihydroxystyrene so that the SiH bond on the modified polysiloxane reacts with the double bond on the 3,4-dihydroxystyrene to obtain a modified monomer.

[0023] The modified filler is prepared by hydrolyzing and condensing tetraethyl orthosilicate as a raw material, and promoting hydroxylation under the action of L-arginine to prepare hydroxy nano-silica, treating the hydroxy nano-silica with KH550 to graft amino groups on the surface to prepare pretreated silica, carrying out anionic ring-opening polymerization with hexamethylcyclotrisiloxane as a reaction monomer, n-butyl lithium as an initiator and dimethylchlorosilane as a capping agent to prepare monohydrogen polysiloxane, reacting the monohydrogen polysiloxane with allyl alcohol glycidyl ether to make Si-H bonds on the monohydrogen polysiloxane react with double bonds on allyl alcohol glycidyl ether to prepare a treating agent, reacting the pretreated silica with the treating agent to make the epoxy groups on the treating agent react with the amino groups on the pretreated silica to generate hydroxy groups to prepare the modified silica, reacting the modified silica with vinyl chloride to make the hydroxy groups on the modified silica react with the chlorine atom sites on the vinyl chloride to prepare the modified filler.

[0024] The surface of the modified filler contains long-chain silicone segments, which enables the paint film to form a hydrophobic film after drying, and the presence of the silica matrix can prevent moisture from directly contacting the polyurethane molecular segments, thereby increasing the water resistance of the paint film. The modified monomer is a hyperbranched structure with silicone segments on the molecular chain. At the same time, the long-chain olefins on the side chain can be grafted with methyl methacrylate and the double bonds on the modified filler when exposed to ultraviolet light, thereby forming new cross-linking sites on the surface of the paint film, increasing the density of the hydrophobic film and further improving the water resistance. At the same time, the side chain contains a catechol structure, which can increase the adhesion effect of the coating. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0026] Example 1

[0027] A method for preparing a water-based environmentally friendly coating comprises the following steps:

[0028] Step A1: adding poly(1,4-butylene adipate) diol to a reaction kettle, introducing nitrogen protection, stirring and adding isophorone diisocyanate at a speed of 120 r / min and a temperature of 70° C., reacting for 30 min, adding 2,2-dihydroxymethylpropionic acid, reacting for 1 h, adding a modified monomer and butanediol, reacting for 1 h, adding triethylamine, reacting for 1 h, adding deionized water, stirring for 2 h at a speed of 500 r / min and a temperature of 25° C., to obtain a polyurethane emulsion;

[0029] Step A2: Weigh the following raw materials in parts by weight: 100 parts of polyurethane emulsion, 0.05 parts of defoaming agent, 1.5 parts of dispersant, 15 parts of modified filler, 3 parts of 1-hydroxycyclohexyl phenyl ketone, 20 parts of methyl methacrylate and 10 parts of water, and mix the raw materials evenly to obtain a water-based environmentally friendly coating.

[0030] The amount ratio of poly(1,4-butylene adipate) diol, isophorone diisocyanate, 2,2-dihydroxymethylpropionic acid, modified monomer, butanediol, triethylamine and deionized water described in step A1 is 12mmo l:23mmo l:1mmo l:1.5mmol:8mmo l:1mmo l:200mL, and the molecular weight of poly(1,4-butylene adipate) diol is 2000.

[0031] The defoaming agent described in step A2 is defoaming agent GP330, and the dispersant is SN-5040 dispersant.

[0032] The modified monomer is prepared by the following steps:

[0033] Step B1: octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and dimethyl sulfoxide are mixed uniformly, nitrogen is introduced for protection, and the mixture is reacted for 3 hours at a speed of 120 r / min and a temperature of 90° C. to obtain a diamine-terminated polysiloxane; oleyl alcohol, epichlorohydrin, boron trifluoride etherate and DMF are mixed uniformly, and the mixture is reacted for 2 hours at a speed of 120 r / min and a temperature of 65° C.; sodium hydroxide solution is added, the mixture is heated to 75° C., and the mixture is reacted for 3 hours to obtain a modifier;

[0034] Step B2: Evenly mix the diamine-terminated polysiloxane, the modifier and DMF, and react for 3 hours at a speed of 150 r / min, a temperature of 40°C and a pH value of 11 to obtain a modified polysiloxane; evenly mix the modified polysiloxane, 3,4-dihydroxystyrene, chloroplatinic acid and DMF, and react for 6 hours at a speed of 120 r / min and a temperature of 70°C to obtain a modified monomer.

[0035] The amount ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane described in step B1 is 2:0.4:3:2, the amount ratio of oleyl alcohol, epichlorohydrin, boron trifluoride etherate and sodium hydroxide solution is 30mmol:30mmol:0.9g:20mL, and the mass fraction of sodium hydroxide solution is 25%.

[0036] The molar ratio of the diamine-terminated polysiloxane and the modifier described in step B2 is 1:4, the molar ratio of the SiH bond on the modified polysiloxane and 3,4-dihydroxystyrene is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 3,4-dihydroxystyrene.

[0037] The modified filler is prepared by the following steps:

[0038] Step C1: L-arginine and deionized water are mixed evenly, and ethyl orthosilicate is added under the conditions of a rotation speed of 500 r / min and a temperature of 20° C., and the temperature is raised to 80° C., and the reaction is carried out for 20 hours to obtain hydroxy nano-silica, and the hydroxy nano-silica is dispersed in ethanol, and KH550 is added under the conditions of a rotation speed of 150 r / min and a temperature of 70° C., and the reaction is carried out for 3 hours to obtain pretreated silica;

[0039] Step C2: n-butyl lithium, n-hexane and benzene are uniformly mixed, argon gas is introduced to remove air, hexamethylcyclotrisiloxane is added under stirring at a speed of 60 r / min and a temperature of 20° C., stirring for 30 min, tetrahydrofuran is added, and the reaction is carried out for 7 h, dimethylchlorosilane is added, and the reaction is carried out for 30 min to obtain monohydrogenpolysiloxane;

[0040] Step C3: Monohydrogenpolysiloxane, allyl alcohol glycidyl ether, chloroplatinic acid and DMF are mixed evenly, and reacted at a speed of 120 r / min and a temperature of 70°C for 3 hours to obtain a treating agent; pretreated silica, the treating agent and DMF are mixed evenly, and reacted at a speed of 200 r / min, a temperature of 40°C and a pH value of 11 for 4 hours to obtain modified silica; modified silica, potassium carbonate and DMF are mixed, and stirred at a speed of 150 r / min and a temperature of 100°C, and vinyl chloride is added, and the reaction is carried out for 3 hours to obtain a modified filler.

[0041] The dosage ratio of L-arginine, deionized water and tetraethyl orthosilicate described in step C1 is 1 mmol:150 mL:100 mmol, and the dosage of KH550 is 1% of the mass of hydroxy nano-silicon dioxide.

[0042] The dosage ratio of n-butyl lithium, n-hexane, benzene, hexamethylcyclotrisiloxane, tetrahydrofuran and dimethylchlorosilane described in step C2 is 7.5g:20mL:10mL:500mmol:30mL:25mmol.

[0043] The molar ratio of monohydrogenpolysiloxane and allyl alcohol glycidyl ether described in step C3 is 1:1, the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol glycidyl ether, and the amount ratio of modified silica, potassium carbonate, DMF and vinyl chloride is 1g:3g:20mL:1.5g.

[0044] Example 2

[0045] A method for preparing a water-based environmentally friendly coating comprises the following steps:

[0046] Step A1: adding poly(1,4-butylene adipate) diol to a reactor, introducing nitrogen protection, stirring and adding isophorone diisocyanate at a speed of 120 r / min and a temperature of 75° C., reacting for 35 min, adding 2,2-dihydroxymethylpropionic acid, reacting for 1 h, adding a modified monomer and butanediol, reacting for 1.5 h, adding triethylamine, reacting for 1 h, adding deionized water, stirring for 3 h at a speed of 600 r / min and a temperature of 25° C., to obtain a polyurethane emulsion;

[0047] Step A2: Weigh the following raw materials in parts by weight: 110 parts of polyurethane emulsion, 0.08 parts of defoaming agent, 2 parts of dispersant, 18 parts of modified filler, 4 parts of 1-hydroxycyclohexyl phenyl ketone, 25 parts of methyl methacrylate and 15 parts of water, and mix the raw materials evenly to obtain a water-based environmentally friendly coating.

[0048] The amount ratio of poly(1,4-butylene adipate) diol, isophorone diisocyanate, 2,2-dihydroxymethylpropionic acid, modified monomer, butanediol, triethylamine and deionized water described in step A1 is 12mmo l:23mmo l:1mmo l:1.5mmol:8mmo l:1mmo l:200mL, and the molecular weight of poly(1,4-butylene adipate) diol is 2000.

[0049] The defoaming agent described in step A2 is defoaming agent GPE3000, and the dispersant is Soka l an CP5 dispersant.

[0050] The modified monomer is prepared by the following steps:

[0051] Step B1: octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and dimethyl sulfoxide are mixed uniformly, nitrogen is introduced for protection, and the mixture is reacted for 4 hours at a speed of 120 r / min and a temperature of 95° C. to obtain a diamine-terminated polysiloxane; oleyl alcohol, epichlorohydrin, boron trifluoride etherate and DMF are mixed uniformly, the mixture is reacted for 2 hours at a speed of 120 r / min and a temperature of 70° C., a sodium hydroxide solution is added, the mixture is heated to 80° C., and the mixture is reacted for 4 hours to obtain a modifier;

[0052] Step B2: Evenly mix the diamine-terminated polysiloxane, the modifier and DMF, and react for 4 hours at a speed of 150 r / min, a temperature of 45°C and a pH value of 12 to obtain a modified polysiloxane; evenly mix the modified polysiloxane, 3,4-dihydroxystyrene, chloroplatinic acid and DMF, and react for 7 hours at a speed of 120 r / min and a temperature of 75°C to obtain a modified monomer.

[0053] The amount ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane described in step B1 is 2:0.4:3:2, the amount ratio of oleyl alcohol, epichlorohydrin, boron trifluoride etherate and sodium hydroxide solution is 30mmol:30mmol:0.9g:20mL, and the mass fraction of sodium hydroxide solution is 25%.

[0054] The molar ratio of the diamine-terminated polysiloxane and the modifier described in step B2 is 1:4, the molar ratio of the Si-H bond on the modified polysiloxane and 3,4-dihydroxystyrene is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 3,4-dihydroxystyrene.

[0055] The modified filler is prepared by the following steps:

[0056] Step C1: L-arginine and deionized water are mixed evenly, and ethyl orthosilicate is added under the conditions of a rotation speed of 600 r / min and a temperature of 20° C., and the temperature is raised to 85° C., and the reaction is carried out for 20 hours to obtain hydroxy nano-silica, and the hydroxy nano-silica is dispersed in ethanol, and KH550 is added under the conditions of a rotation speed of 200 r / min and a temperature of 75° C., and the reaction is carried out for 4 hours to obtain pretreated silica;

[0057] Step C2: n-butyl lithium, n-hexane and benzene are mixed uniformly, argon gas is introduced to remove air, hexamethylcyclotrisiloxane is added under stirring at a speed of 60 r / min and a temperature of 25° C., stirring is performed for 35 minutes, tetrahydrofuran is added, and the reaction is carried out for 8 hours, dimethylchlorosilane is added, and the reaction is carried out for 35 minutes to obtain monohydrogenpolysiloxane;

[0058] Step C3: Monohydrogenpolysiloxane, allyl alcohol glycidyl ether, chloroplatinic acid and DMF are mixed evenly, and reacted at a speed of 120 r / min and a temperature of 75°C for 4 hours to obtain a treating agent; pretreated silica, the treating agent and DMF are mixed evenly, and reacted at a speed of 200 r / min, a temperature of 45°C and a pH value of 12 for 5 hours to obtain modified silica; modified silica, potassium carbonate and DMF are mixed, and stirred at a speed of 150 r / min and a temperature of 105°C, and vinyl chloride is added, and the reaction is carried out for 4 hours to obtain a modified filler.

[0059] The dosage ratio of L-arginine, deionized water and tetraethyl orthosilicate described in step C1 is 1 mmol:150 mL:100 mmol, and the dosage of KH550 is 1% of the mass of hydroxy nano-silicon dioxide.

[0060] The dosage ratio of n-butyl lithium, n-hexane, benzene, hexamethylcyclotrisiloxane, tetrahydrofuran and dimethylchlorosilane described in step C2 is 7.5g:20mL:10mL:500mmol:30mL:25mmol.

[0061] The molar ratio of monohydrogenpolysiloxane and allyl alcohol glycidyl ether described in step C3 is 1:1, the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol glycidyl ether, and the amount ratio of modified silica, potassium carbonate, DMF and vinyl chloride is 1g:3g:20mL:1.5g.

[0062] Example 3

[0063] A method for preparing a water-based environmentally friendly coating comprises the following steps:

[0064] Step A1: adding poly(1,4-butylene adipate) diol to a reactor, introducing nitrogen protection, stirring and adding isophorone diisocyanate at a speed of 150 r / min and a temperature of 80° C., reacting for 40 min, adding 2,2-dihydroxymethylpropionic acid, reacting for 1.5 h, adding a modified monomer and butanediol, reacting for 1.5 h, adding triethylamine, reacting for 1.5 h, adding deionized water, stirring for 3 h at a speed of 600 r / min and a temperature of 30° C., to obtain a polyurethane emulsion;

[0065] Step A2: Weigh the following raw materials in parts by weight: 120 parts of polyurethane emulsion, 0.1 parts of defoaming agent, 3 parts of dispersant, 20 parts of modified filler, 5 parts of 1-hydroxycyclohexyl phenyl ketone, 30 parts of methyl methacrylate and 20 parts of water, and mix the raw materials evenly to obtain a water-based environmentally friendly coating.

[0066] The amount ratio of poly(1,4-butylene adipate) diol, isophorone diisocyanate, 2,2-dihydroxymethylpropionic acid, modified monomer, butanediol, triethylamine and deionized water described in step A1 is 12mmo l:23mmo l:1mmo l:1.5mmol:8mmo l:1mmo l:200mL, and the molecular weight of poly(1,4-butylene adipate) diol is 2000.

[0067] The defoaming agent described in step A2 is defoaming agent DF103, and the dispersant is Ecodis P90 dispersant.

[0068] The modified monomer is prepared by the following steps:

[0069] Step B1: octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and dimethyl sulfoxide are mixed uniformly, nitrogen is introduced for protection, and the mixture is reacted for h at a speed of 150 r / min and a temperature of 95° C. to obtain a diamine-terminated polysiloxane; oleyl alcohol, epichlorohydrin, boron trifluoride etherate and DMF are mixed uniformly, and the mixture is reacted for 3 h at a speed of 150 r / min and a temperature of 70° C.; sodium hydroxide solution is added, the mixture is heated to 80° C., and the mixture is reacted for 5 h to obtain a modifier;

[0070] Step B2: Evenly mix the diamine-terminated polysiloxane, the modifier and DMF, and react for 5 hours at a speed of 200 r / min, a temperature of 50°C and a pH value of 12 to obtain a modified polysiloxane; evenly mix the modified polysiloxane, 3,4-dihydroxystyrene, chloroplatinic acid and DMF, and react for 8 hours at a speed of 150 r / min and a temperature of 80°C to obtain a modified monomer.

[0071] The amount ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane described in step B1 is 2:0.4:3:2, the amount ratio of oleyl alcohol, epichlorohydrin, boron trifluoride etherate and sodium hydroxide solution is 30mmol:30mmol:0.9g:20mL, and the mass fraction of sodium hydroxide solution is 25%.

[0072] The molar ratio of the diamine-terminated polysiloxane and the modifier described in step B2 is 1:4, the molar ratio of the Si-H bond on the modified polysiloxane and 3,4-dihydroxystyrene is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 3,4-dihydroxystyrene.

[0073] The modified filler is prepared by the following steps:

[0074] Step C1: L-arginine and deionized water are mixed evenly, and ethyl orthosilicate is added under the conditions of a rotation speed of 600 r / min and a temperature of 25° C., and the temperature is raised to 85° C., and the reaction is carried out for 25 hours to obtain hydroxy nano-silica, and the hydroxy nano-silica is dispersed in ethanol, and KH550 is added under the conditions of a rotation speed of 200 r / min and a temperature of 80° C., and the reaction is carried out for 5 hours to obtain pretreated silica;

[0075] Step C2: n-butyl lithium, n-hexane and benzene are uniformly mixed, argon gas is introduced to remove air, hexamethylcyclotrisiloxane is added under stirring at a speed of 80 r / min and a temperature of 25° C., stirring is performed for 40 min, tetrahydrofuran is added, and the reaction is carried out for 9 h, dimethylchlorosilane is added, and the reaction is carried out for 40 min to obtain monohydrogenpolysiloxane;

[0076] Step C3: Monohydrogen polysiloxane, allyl alcohol glycidyl ether, chloroplatinic acid and DMF are mixed evenly, and reacted at a speed of 150 r / min and a temperature of 80°C for 5 hours to obtain a treating agent; pretreated silica, the treating agent and DMF are mixed evenly, and reacted at a speed of 300 r / min, a temperature of 50°C and a pH value of 12 for 6 hours to obtain modified silica; modified silica, potassium carbonate and DMF are mixed, and stirred at a speed of 200 r / min and a temperature of 110°C, and vinyl chloride is added, and the reaction is carried out for 5 hours to obtain a modified filler.

[0077] The dosage ratio of L-arginine, deionized water and tetraethyl orthosilicate described in step C1 is 1 mmol:150 mL:100 mmol, and the dosage of KH550 is 1% of the mass of hydroxy nano-silicon dioxide.

[0078] The dosage ratio of n-butyl lithium, n-hexane, benzene, hexamethylcyclotrisiloxane, tetrahydrofuran and dimethylchlorosilane described in step C2 is 7.5g:20mL:10mL:500mmol:30mL:25mmol.

[0079] The molar ratio of monohydrogenpolysiloxane and allyl alcohol glycidyl ether described in step C3 is 1:1, the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol glycidyl ether, and the amount ratio of modified silica, potassium carbonate, DMF and vinyl chloride is 1g:3g:20mL:1.5g.

[0080] Comparative Example 1

[0081] Compared with Example 1, this comparative example uses styrene instead of 3,4-dihydroxystyrene, and the other steps are the same.

[0082] Comparative Example 2

[0083] Compared with Example 1, this comparative example uses propylene oxide instead of the modifier, and the other steps are the same.

[0084] Comparative Example 3

[0085] Compared with Example 1, this comparative example uses nano silicon dioxide instead of the modified filler, and the other steps are the same.

[0086] Comparative Example 4

[0087] Compared with Example 1, this comparative example uses propylene oxide instead of the treating agent, and the other steps are the same.

[0088] The water-based coatings prepared in Examples 1-3 and Comparative Examples 1-4 were coated on tinplate in accordance with the standard of GB / T1733-1993, irradiated with 365nm ultraviolet light for 60s, the coating thickness was 85μm, and the edges were sealed with paraffin. The state of the paint film was observed by immersing in water, and the adhesion level was tested in accordance with the standard of GB / T9286-2021. The test results are shown in the following table.

[0089]

[0090] It can be seen from the above table that the present application has a very good water resistance effect and excellent adhesion ability.

[0091] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field 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 concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a water-based environmentally friendly coating, characterized in that: The specific steps include: Step A1: adding poly(1,4-butylene adipate) diol to a reaction kettle, introducing nitrogen for protection, stirring, adding isophorone diisocyanate, reacting, adding 2,2-dihydroxymethyl propionic acid, reacting, adding a modified monomer and butanediol, reacting, adding triethylamine, reacting, adding deionized water, stirring, and preparing a polyurethane emulsion; Step A2: Weigh the following raw materials in parts by weight: 100-120 parts of polyurethane emulsion, 0.05-0.1 parts of defoaming agent, 1.5-3 parts of dispersant, 15-20 parts of modified filler, 3-5 parts of 1-hydroxycyclohexyl phenyl ketone, 20-30 parts of methyl methacrylate and 10-20 parts of water, and mix the raw materials evenly to obtain a water-based environmentally friendly coating.

2. The method for preparing a water-based environmentally friendly coating according to claim 1, characterized in that: The amount ratio of poly(1,4-butylene adipate) diol, isophorone diisocyanate, 2,2-dimethylol propionic acid, modified monomer, butanediol, triethylamine and deionized water in step A1 is 12 mmol: 23 mmol: 1 mmol: 1.5 mmol: 8 mmol: 1 mmol: 200 mL.

3. The method for preparing a water-based environmentally friendly coating according to claim 1, characterized in that: The modified monomer is prepared by the following steps: Step B1: octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and dimethyl sulfoxide are uniformly mixed, nitrogen is introduced for protection, and a reaction is carried out to obtain a diamine-terminated polysiloxane; oleyl alcohol, epichlorohydrin, boron trifluoride ether and DMF are mixed for reaction, a sodium hydroxide solution is added, and the temperature is raised for reaction to obtain a modifier; Step B2: Mix and react the diamine-terminated polysiloxane, a modifier and DMF to obtain a modified polysiloxane, and mix and react the modified polysiloxane, 3,4-dihydroxystyrene, chloroplatinic acid and DMF to obtain a modified monomer.

4. The method for preparing a water-based environmentally friendly coating according to claim 3, characterized in that: The amount ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane described in step B1 is 2:0.4:3:2, and the amount ratio of oleyl alcohol, epichlorohydrin, boron trifluoride etherate and sodium hydroxide solution is 30mmol:30mmol:0.9g:20mL.

5. The method for preparing a water-based environmentally friendly coating according to claim 3, characterized in that: The molar ratio of the diamine-terminated polysiloxane and the modifier in step B2 is 1:4, and the molar ratio of the Si-H bond on the modified polysiloxane and 3,4-dihydroxystyrene is 1:

1.

6. The method for preparing a water-based environmentally friendly coating according to claim 1, characterized in that: The modified filler is prepared by the following steps: Step C1: L-arginine and deionized water are mixed and stirred, and ethyl orthosilicate is added, and the temperature is raised to react to obtain hydroxy nano-silica, and the hydroxy nano-silica is dispersed in ethanol, stirred and KH550 is added to react to obtain pretreated silica; Step C2: n-butyl lithium, n-hexane and benzene are uniformly mixed, argon gas is introduced to remove air, hexamethylcyclotrisiloxane is added with stirring, tetrahydrofuran is added, reacted, dimethylchlorosilane is added, reacted to obtain monohydrogenpolysiloxane; Step C3: Monohydrogen polysiloxane, allyl alcohol glycidyl ether, chloroplatinic acid and DMF are mixed and reacted to obtain a treating agent, pretreated silica, the treating agent and DMF are mixed and reacted to obtain modified silica, the modified silica, potassium carbonate and DMF are mixed and stirred, and vinyl chloride is added to react to obtain a modified filler.

7. The method for preparing a water-based environmentally friendly coating according to claim 6, characterized in that: The dosage ratio of L-arginine, deionized water and tetraethyl orthosilicate described in step C1 is 1mmol:150mL:100mmol, and the dosage of KH550 is 1% of the mass of hydroxyl nano-silica.

8. The method for preparing a water-based environmentally friendly coating according to claim 6, characterized in that: The amount ratio of n-butyl lithium, n-hexane, benzene, hexamethylcyclotrisiloxane, tetrahydrofuran and dimethylchlorosilane described in step C2 is 7.5g:20mL:10mL:500mmol:30mL:25mmol.

9. The method for preparing a water-based environmentally friendly coating according to claim 6, characterized in that: The molar ratio of monohydrogenpolysiloxane and allyl alcohol glycidyl ether in step C3 is 1:1, and the amount ratio of modified silica, potassium carbonate, DMF and vinyl chloride is 1g:3g:20mL:1.5g.

10. A water-based environmentally friendly paint, characterized in that: Prepared according to any one of claims 1 to 9.

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