Non-combustible water-based aerosol spray paint and preparation method thereof

Abstract

The invention discloses incombustible water-based aerosol spray paint and a preparation method thereof, and relates to the technical field of spray paint. When the non-combustible water-based aerosol spray paint is prepared, firstly, p-(triethoxysilyl) acetophenone reacts with trimethylchlorosilane, and then the reaction product and tetramethyl tetravinyl cyclotetrasiloxane are subjected to ring opening polymerization to obtain modified polysiloxane; grafting epoxy resin with 4-vinyl-methyl benzoate, reacting with modified polysiloxane to obtain modified epoxy resin, and emulsifying to obtain a modified epoxy resin emulsion; secondly, reacting the silicon dioxide subjected to acylating chlorination with 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine nitroxide free radicals, reacting with 3-(3-thienyl) propionaldehyde, and reacting with thiophene and 3-vinyl thiophene to obtain modified silicon dioxide; and finally, mixing the modified epoxy resin emulsion, pure water, the modified silicon dioxide, a curing agent and a photoinitiator to prepare the incombustible water-based aerosol spray paint.

Description

Technical Field

[0001] The invention relates to the technical field of spray paint, in particular to a non-flammable water-based aerosol spray paint and a preparation method thereof. Background Art

[0002] Paint is a material that is coated on the surface of an object and can form a firmly adhered continuous film. This film usually has a protective and decorative function.

[0003] For different application fields, traditional paints often lack some special functions to meet the use requirements in different scenarios. For some flammable substrates, non-combustible paints can reduce the flammability of the surface of the coated substrate and block the rapid spread of fire, thereby achieving the effect of preventing fire and improving safety;

[0004] In addition, for metal substrates that are susceptible to corrosion by corrosive media in the air, the paint needs to have good anti-corrosion properties. For substrates that are used outdoors for a long time, the paint on their surface is prone to aging during long-term use, such as discoloration and cracking. For this reason, a non-flammable, anti-corrosion, and anti-UV aging paint is needed to broaden the application areas of the paint. Summary of the invention

[0005] The object of the present invention is to provide a non-flammable water-based aerosol spray paint and a preparation method thereof, so as to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The invention discloses a non-flammable water-based aerosol spray paint, which is prepared by mixing modified epoxy resin emulsion, pure water, modified silicon dioxide, a curing agent and a photoinitiator.

[0008] Preferably, the modified epoxy resin emulsion is obtained by grafting 4-vinyl-methyl benzoate onto epoxy resin, reacting with modified polysiloxane, and then emulsifying; the modified polysiloxane is obtained by reacting p-(triethoxysilyl)acetophenone with trimethylchlorosilane, and then ring-opening polymerization with tetramethyltetravinylcyclotetrasiloxane.

[0009] Preferably, the modified silica is silica modified with γ-aminopropyltriethoxysilane, reacted with maleic anhydride, and then chlorinated with thionyl chloride to obtain chlorinated silica, the chlorinated silica reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical, and then reacted with 3-(3-thienyl)propionaldehyde, and then reacted with thiophene and 3-vinylthiophene to obtain the obtained silica.

[0010] A method for preparing a non-flammable water-based aerosol spray paint comprises the following preparation steps:

[0011] (1) mixing an organosilicon monomer and tetramethyltetravinylcyclotetrasiloxane in a mass ratio of 1:(5-6), adding a 98wt% sulfuric acid solution of 0.2-0.3 times the mass of the organosilicon monomer, heating to 35°C for reaction for 6h, distilling under reduced pressure at 4.67x10-5MPa for 40-50min, and washing with pure water for 6-8 times to obtain a modified polysiloxane;

[0012] (2) epoxy resin and n-butanol are mixed in a mass ratio of 1:(50-60), benzoyl peroxide of 1%-2% by mass of epoxy resin is added, the temperature is raised to 75-85° C. under nitrogen protection, 4-vinyl-benzoic acid methyl ester solution of 0.3-0.5 times by mass of epoxy resin is added dropwise at a rate of 1 mL / min, the reaction is continued for 4 h after the addition is completed, the mixture is cooled to 50° C., the pH is adjusted to 7-8 with 28wt% ammonia water, and the pre-modified epoxy resin is obtained by distillation under reduced pressure;

[0013] (3) Sodium hydride and solvent are mixed in a mass ratio of 1:(7-8), stirred for 10-20 min under nitrogen protection at 0-4°C to obtain a sodium hydride solution, a pre-modified epoxy resin, a modified polysiloxane, and a solvent are mixed in a mass ratio of 1:(1.2-1.3):(10-12), and added dropwise at a rate of 2.5 mL / min to a sodium hydride solution 7-8 times the mass of the pre-modified epoxy resin, reacted at 30°C for 90-100 min, the solvent was removed by reduced pressure distillation, and washed with pure water for 3-4 times, and vacuum dried at 50-60°C for 12 h to obtain a modified epoxy resin; pure water, modified epoxy resin, and emulsifier are weighed in a mass ratio of 100:50:10, the modified epoxy resin and emulsifier are stirred at 70°C and 1000 r / min for 20 min, pure water is added, and stirring is continued for 30 min to obtain a modified epoxy resin emulsion;

[0014] (4) mixing silicon dioxide, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical and dichloromethane in a mass ratio of 1:(2-3):(10-12), adding pyridine in an amount of 0.5-0.7 times the mass of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical dropwise at a rate of 1 mL / min at -5-4°C, continuing the reaction for 8-10 hours after the addition is completed, filtering, washing with pure water 3-4 times, and drying at 50-60°C for 1 hour. 2h to obtain nitroxide free radical silicon dioxide; nitroxide free radical silicon dioxide, 3-(3-thienyl)propionaldehyde, and tetrahydrofuran are mixed uniformly in a mass ratio of 1:(2-3):(50-60), and a 30wt% hydrogen peroxide solution of 0.4 times the volume of tetrahydrofuran is added dropwise at 5-10°C, and then cuprous chloride of 0.03 times the mass of the acyl chloride silicon dioxide is added, the temperature is raised to 20-30°C, and after reacting for 24h, the tetrahydrofuran is removed by vacuum rotary evaporation to obtain pre-modified silicon dioxide;

[0015] (5) Pre-modified silica, thiophene, 3-vinylthiophene, ferric chloride, and chloroform are mixed in a mass ratio of 1:(0.1-0.12):(0.03-0.05):(5-6):20, stirred for 8-10 hours, filtered, and dispersed again in a 1 mol / L hydrochloric acid solution of 20-30 times the mass of the pre-modified silica, stirred for 5-10 minutes, filtered, washed 3-4 times with a 1 mol / L hydrochloric acid solution, washed 3-4 times with pure water, and dried at 50-60° C. for 12 hours to obtain modified silica;

[0016] (6) Weigh the following components by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 3-5 parts of modified silica, 22-24 parts of curing agent, and 0.3-0.5 parts of photoinitiator, and mix the above components to obtain non-flammable water-based aerosol spray paint.

[0017] Preferably, the preparation method of the organosilicon monomer in step (1) is: trimethylchlorosilane, p-(triethoxysilyl)acetophenone, and hydroquinone are mixed in a mass ratio of 1:(0.9-1.0):(0.03-0.05), and ethanol 2.3-2.5 times the mass of trimethylchlorosilane is added dropwise at a rate of 2.5 mL / min. After the addition is completed, stirring is performed at 20°C for 30 minutes, and then pure water 0.5 times the mass of ethanol is added dropwise at a rate of 2.5 mL / min. After the addition is completed, the temperature is raised to 50°C, and pure water 0.5 times the mass of ethanol is continued to be added dropwise at a rate of 2.5 mL / min. After the addition is completed, the temperature is kept for 10 hours, and the mixture is allowed to stand for 40-50 minutes. The water layer is discarded and the organic phase is washed with pure water 7-8 times. The mixture is distilled under reduced pressure at 1.33x10-3MPa and 100-110°C, and the fractions are collected to obtain the organosilicon monomer.

[0018] Preferably, the epoxy resin model of step (2) is E-44; the 4-vinyl-benzoic acid methyl ester solution is obtained by mixing 4-vinyl-benzoic acid methyl ester and n-butanol in a mass ratio of 1:10.

[0019] Preferably, the solvent in step (3) is a mixture of dimethyl sulfoxide and tetrahydrofuran in a volume ratio of 1:1; and the emulsifier is OP-10.

[0020] Preferably, the preparation method of the acylated silicon dioxide in step (4) is: mixing silicon dioxide, γ-aminopropyltriethoxysilane, toluene and triethylamine in a mass ratio of 1:(2-3):(20-30):(0.1-0.2), heating to 110° C. for reaction for 4-5 hours, filtering and washing with acetone for 3-4 times after the reaction to obtain amination silicon dioxide; mixing amination silicon dioxide and ethanol in a mass ratio of 1:(30-40), ultrasonicating for 10-20 minutes, Add glutaric anhydride 3-4 times the mass of aminosilica, react at 37°C for 3-4 hours, filter and wash with 0.1M sodium chloride solution 3-4 times, and vacuum dry at 50-60°C for 12 hours to obtain carboxylated silica, mix carboxylated silica and thionyl chloride in a mass ratio of 1:20, reflux at 70°C for 24 hours, cool to room temperature, filter, wash with tetrahydrofuran 5-6 times, and dry at 50-60°C for 12 hours to obtain acyl chloride silica.

[0021] Preferably, the silicon dioxide model is VK-SP30S.

[0022] Preferably, the curing agent model in step (6) is T-403; and the photoinitiator is 1-hydroxycyclohexyl phenyl ketone.

[0023] The present invention also provides a method for using the non-flammable aerosol spray paint prepared by the above-mentioned method for preparing the non-flammable water-based aerosol spray paint. The method of use is: use a paint spray gun to spray the non-flammable water-based aerosol spray paint on the surface of the tinplate sheet, and then place it in a UV curing machine for curing. The non-flammable water-based aerosol spray paint needs to be used up within 4 hours.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0025] The present invention prepares the non-flammable water-based aerosol spray paint by firstly reacting p-(triethoxysilyl)acetophenone with trimethylchlorosilane, and then ring-opening polymerization with tetramethyltetravinylcyclotetrasiloxane to obtain modified polysiloxane; grafting epoxy resin with 4-vinyl-benzoic acid methyl ester, and then reacting with the modified polysiloxane to obtain modified epoxy resin, and emulsifying the modified epoxy resin to obtain modified epoxy resin emulsion; secondly, reacting diisocyanate modified with γ-aminopropyltriethoxysilane with 4-vinyl-benzoic acid methyl ester; and finally reacting with tetramethyltetravinylcyclotetrasiloxane to obtain modified polysiloxane. Silicon dioxide is reacted with maleic anhydride, and then chlorinated with thionyl chloride to obtain chlorinated silicon dioxide, chlorinated silicon dioxide is reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical, and then reacted with 3-(3-thienyl)propionaldehyde, and then reacted with thiophene and 3-vinylthiophene to obtain modified silicon dioxide; finally, modified epoxy resin emulsion, pure water, modified silicon dioxide, curing agent and photoinitiator are mixed to obtain non-flammable water-based aerosol spray paint.

[0026] Firstly, p-(triethoxysilyl)acetophenone and trimethylchlorosilane are reacted, and then the modified polysiloxane is ring-opening polymerized with tetramethyltetravinylcyclotetrasiloxane to obtain a modified polysiloxane, wherein one end of the modified polysiloxane is an acetophenone structure, and the main chain contains a carbon-carbon double bond. 4-vinyl-methyl benzoate is grafted onto epoxy resin, and the side chain of the epoxy resin is grafted with a methyl benzoate structure. Methyl benzoate then undergoes a condensation reaction with the acetophenone at one end of the modified polysiloxane to generate a dibenzoylmethane structure. There is a tautomeric equilibrium between keto and enol forms in the dibenzoylmethane structure. The tautomerism process between the two structures can convert light energy into heat energy or harmless low-energy radiation, thereby effectively absorbing ultraviolet rays and giving the spray paint good anti-ultraviolet aging performance; the lower surface tension of the polysiloxane can increase the surface energy of the spray paint, thereby improving its water resistance and thus improving its corrosion resistance.

[0027] Secondly, the silicon dioxide modified by γ-aminopropyltriethoxysilane is reacted with maleic anhydride, and then chlorinated with thionyl chloride to obtain chlorinated silicon dioxide. The chlorinated silicon dioxide is reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine nitrogen oxide free radical, and then reacted with 3-(3-thienyl)propionaldehyde to generate an N-alkoxyamine structure. The N-alkoxyamine structure can not only improve the ultraviolet light stability of the material, but also help to improve the flame retardant properties of the material. At the same time, the thiophene structure is also introduced, and then polymerized with thiophene and 3-vinylthiophene on the surface of silicon dioxide to form polythiophene containing double bonds. Polythiophene can form a dense oxide film protective layer on the surface of the metal substrate. This protective film can effectively prevent corrosive ions and solutions from penetrating into the surface of the metal substrate, thereby playing a role of mechanical barrier. This barrier effect can reduce the corrosion rate and extend the service life of the metal substrate.

[0028] Finally, the modified epoxy resin emulsion, pure water, modified silica, curing agent, and photoinitiator are mixed to prepare a non-flammable water-based aerosol spray paint; under the action of the photoinitiator and the irradiation of ultraviolet light, the modified epoxy resin emulsion and modified silica produce secondary cross-linking through double bond free radical polymerization to generate a denser cross-linking network, which can enhance the mechanical properties of the coating formed by the spray paint. DETAILED DESCRIPTION

[0029] 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 making creative work are within the scope of protection of the present invention.

[0030] The epoxy resin model used in the following examples and comparative examples is E-44; the 4-vinyl-methyl benzoate solution used is obtained by mixing 4-vinyl-methyl benzoate and n-butanol in a mass ratio of 1:10; the solvent used is obtained by mixing dimethyl sulfoxide and tetrahydrofuran in a volume ratio of 1:1; the emulsifier used is OP-10; the silica model used is VK-SP30S; the curing agent model used is T-403; and the photoinitiator used is 1-hydroxycyclohexyl phenyl ketone.

[0031] Embodiment 1:

[0032] A method for preparing a non-flammable water-based aerosol spray paint, the method comprising the following preparation steps:

[0033] (1) Trimethylchlorosilane, p-(triethoxysilyl)acetophenone, and hydroquinone were mixed in a mass ratio of 1:0.9:0.03, and ethanol (2.3 times the mass of trimethylchlorosilane) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was stirred at 20°C for 30 min, and then pure water (0.5 times the mass of ethanol) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was heated to 50°C, and pure water (0.5 times the mass of ethanol) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was kept warm for 10 h, allowed to stand for 50 min, the water layer was discarded, and the organic phase was washed 7 times with pure water. -3 MPa, distill under reduced pressure at 10 ° C, collect the fractions to obtain the organosilicon monomer; mix the organosilicon monomer and tetramethyltetravinylcyclotetrasiloxane in a mass ratio of 1:5, add 0.2 times the mass of the organosilicon monomer 98wt% sulfuric acid solution, heat to 35 ° C for 6h, and at 4.67x10 -5 MPa under reduced pressure distillation for 50 min, and washed with pure water 8 times to obtain modified polysiloxane;

[0034] (2) epoxy resin and n-butanol were mixed in a mass ratio of 1:50, benzoyl peroxide (1% by mass of epoxy resin) was added, the temperature was raised to 85°C under nitrogen protection, 4-vinyl-benzoic acid methyl ester solution (0.3 times by mass of epoxy resin) was added dropwise at a rate of 1 mL / min, the reaction was continued for 4 h after the addition was completed, the mixture was cooled to 50°C, the pH was adjusted to 8 with 28 wt% ammonia water, and the pre-modified epoxy resin was obtained by distillation under reduced pressure;

[0035] (3) Sodium hydride and solvent are mixed in a mass ratio of 1:7, stirred for 20 minutes at 4°C under nitrogen protection to obtain a sodium hydride solution, pre-modified epoxy resin, modified polysiloxane, and solvent are mixed in a mass ratio of 1:1.2:10, and added dropwise at a rate of 2.5 mL / min to a sodium hydride solution 7 times the mass of the pre-modified epoxy resin, reacted at 30°C for 100 minutes, and the solvent was removed by vacuum distillation and washed with pure water 4 times, and vacuum dried at 60°C for 12 hours to obtain a modified epoxy resin; pure water, modified epoxy resin, and emulsifier are weighed in a mass ratio of 100:50:10, and the modified epoxy resin and emulsifier are stirred at 70°C and 1000 r / min for 20 minutes, and then pure water is added, and stirring is continued for 30 minutes to obtain a modified epoxy resin emulsion;

[0036] (4) Silica, γ-aminopropyltriethoxysilane, toluene, and triethylamine were mixed in a mass ratio of 1:2:20:0.1, heated to 110°C for reaction for 5 hours, filtered and washed with acetone 4 times after the reaction was completed to obtain amino silica; amino silica and ethanol were mixed in a mass ratio of 1:30, ultrasonicated for 20 minutes, glutaric anhydride 3 times the mass of amino silica was added, reacted at 37°C for 4 hours, filtered and washed with 0.1M sodium chloride solution 4 times, and vacuum dried at 60°C for 12 hours to obtain carboxylated silica; carboxylated silica and thionyl chloride were mixed in a mass ratio of 1:20, refluxed at 70°C for reaction for 24 hours, cooled to room temperature, filtered and washed with tetrahydrofuran 6 times, and dried at 60°C for 12 hours to obtain chlorinated silica; chlorinated silica, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical and dichloromethane are mixed in a mass ratio of 1:2:10, and pyridine with a mass of 0.5 times that of the 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical is added dropwise at a rate of 1 mL / min at 4°C. After the addition is completed, the reaction is continued for 10 hours, filtered and washed with pure water for 3 times, and dried at 60°C for 12 hours to obtain nitroxide free radical silicon dioxide; nitroxide free radical silicon dioxide, 3-(3-thienyl)propanal, and tetrahydrofuran are mixed in a mass ratio of 1:2:50, and a 30wt% hydrogen peroxide solution with a volume of 0.4 times that of tetrahydrofuran is added dropwise at 10°C, and then cuprous chloride with a volume of 0.03 times that of the acyl chloride silicon dioxide is added, the temperature is raised to 30°C, and after reacting for 24 hours, the tetrahydrofuran is removed by vacuum rotary evaporation to obtain pre-modified silica;

[0037] (5) Pre-modified silica, thiophene, 3-vinylthiophene, ferric chloride, and chloroform were mixed in a mass ratio of 1:0.1:0.03:5:20, stirred for 10 hours, filtered, and dispersed again in a 1 mol / L hydrochloric acid solution with a mass of 20 times that of the pre-modified silica, stirred for 10 minutes, filtered, washed 4 times with a 1 mol / L hydrochloric acid solution, washed 4 times with pure water, and dried at 60° C. for 12 hours to obtain modified silica;

[0038] (6) The following components were weighed by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 3 parts of modified silica, 22 parts of curing agent, and 0.3 parts of photoinitiator, and the above components were mixed for 5 minutes to obtain a non-flammable water-based aerosol spray paint.

[0039] Embodiment 2:

[0040] A method for preparing a non-flammable water-based aerosol spray paint, the method comprising the following preparation steps:

[0041] (1) Trimethylchlorosilane, p-(triethoxysilyl)acetophenone, and hydroquinone were mixed in a mass ratio of 1:0.95:0.04, and ethanol (2.4 times the mass of trimethylchlorosilane) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was stirred at 20°C for 30 min, and then pure water (0.5 times the mass of ethanol) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was heated to 50°C, and pure water (0.5 times the mass of ethanol) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was kept warm for 10 h, allowed to stand for 45 min, the water layer was discarded, and the organic phase was washed 7 times with pure water. -3 MPa, and distilled under reduced pressure at 105°C, collecting fractions to obtain an organosilicon monomer; the organosilicon monomer and tetramethyltetravinylcyclotetrasiloxane were mixed at a mass ratio of 1:5.5, and a 98wt% sulfuric acid solution of 0.25 times the mass of the organosilicon monomer was added, and the temperature was raised to 35°C for reaction for 6h, and the mixture was stirred at 4.67x10 -5 MPa under reduced pressure distillation for 45 min, and washed with pure water 7 times to obtain modified polysiloxane;

[0042] (2) epoxy resin and n-butanol were mixed in a mass ratio of 1:55, benzoyl peroxide (1.5% by mass of epoxy resin) was added, the temperature was raised to 70°C under nitrogen protection, 4-vinyl-benzoic acid methyl ester solution (0.4 times by mass of epoxy resin) was added dropwise at a rate of 1 mL / min, the reaction was continued for 4 h after the addition was completed, the mixture was cooled to 50°C, the pH was adjusted to 7.5 with 28 wt% ammonia water, and the pre-modified epoxy resin was obtained by distillation under reduced pressure;

[0043] (3) Sodium hydride and solvent were mixed in a mass ratio of 1:7.5, stirred for 15 minutes at 3°C ​​under nitrogen protection to obtain a sodium hydride solution, and pre-modified epoxy resin, modified polysiloxane, and solvent were mixed in a mass ratio of 1:1.25:11, and added dropwise at a rate of 2.5 mL / min to a sodium hydride solution 7.5 times the mass of the pre-modified epoxy resin, reacted at 30°C for 95 minutes, and the solvent was removed by vacuum distillation and washed with pure water for 3 times, and vacuum dried at 55°C for 12 hours to obtain a modified epoxy resin; pure water, modified epoxy resin, and emulsifier were weighed in a mass ratio of 100:50:10, and the modified epoxy resin and emulsifier were stirred at 70°C and 1000 r / min for 20 minutes, and then pure water was added, and stirring was continued for 30 minutes to obtain a modified epoxy resin emulsion;

[0044] (4) Silica, γ-aminopropyltriethoxysilane, toluene, and triethylamine were mixed in a mass ratio of 1:2.5:25:0.15, heated to 110°C for reaction for 4.5 hours, filtered and washed with acetone three times after the reaction was completed to obtain amino silica; amino silica and ethanol were mixed in a mass ratio of 1:35, ultrasonicated for 15 minutes, 3.5 times the mass of amino silica glutaric anhydride was added, reacted at 37°C for 3.5 hours, filtered and washed with 0.1M sodium chloride solution three times, and vacuum dried at 55°C for 12 hours to obtain carboxylated silica; carboxylated silica and thionyl chloride were mixed in a mass ratio of 1:20, refluxed at 70°C for reaction for 24 hours, cooled to room temperature, filtered and washed with tetrahydrofuran five times, and dried at 55°C for 12 hours to obtain chlorinated silica; chlorinated silica Silicon oxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical, and dichloromethane are mixed in a mass ratio of 1:2.5:11, and pyridine with a mass of 0.6 times that of the 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical is added dropwise at a rate of 1 mL / min at 0°C. After the addition is completed, the reaction is continued for 9 hours, filtered, washed with pure water for 3 times, and dried at 55°C for 12 hours to obtain nitroxide free radical silicon dioxide; nitroxide free radical silicon dioxide, 3-(3-thienyl)propanal, and tetrahydrofuran are mixed in a mass ratio of 1:2.5:55, and a 30wt% hydrogen peroxide solution with a volume of 0.4 times that of tetrahydrofuran is added dropwise at 7°C, and then cuprous chloride with a mass of 0.03 times that of the chlorinated silicon dioxide is added, the temperature is raised to 25°C, and after reacting for 24 hours, the tetrahydrofuran is removed by vacuum rotary evaporation to obtain pre-modified silicon dioxide;

[0045] (5) Pre-modified silica, thiophene, 3-vinylthiophene, ferric chloride, and chloroform were mixed in a mass ratio of 1:0.11:0.04:5.5:20, stirred for 9 hours, filtered, and dispersed again in a 1 mol / L hydrochloric acid solution with a mass of 25 times that of the pre-modified silica, stirred for 5 minutes, filtered, washed 3 times with a 1 mol / L hydrochloric acid solution, washed 3 times with pure water, and dried at 55° C. for 12 hours to obtain modified silica;

[0046] (6) The following components were weighed by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 4 parts of modified silica, 23 parts of curing agent, and 0.4 parts of photoinitiator, and the above components were mixed for 4 minutes to obtain a non-flammable water-based aerosol spray paint.

[0047] Embodiment 3:

[0048] A method for preparing a non-flammable water-based aerosol spray paint, the method comprising the following preparation steps:

[0049] (1) Trimethylchlorosilane, p-(triethoxysilyl)acetophenone, and hydroquinone were mixed in a mass ratio of 1:1.0:0.05, and ethanol (2.5 times the mass of trimethylchlorosilane) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was stirred at 20°C for 30 min, and then pure water (0.5 times the mass of ethanol) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was heated to 50°C, and pure water (0.5 times the mass of ethanol) was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the mixture was kept warm for 10 h, allowed to stand for 40 min, the water layer was discarded, and the organic phase was washed 8 times with pure water. -3 MPa, distill under reduced pressure at 100 ° C, collect the fractions to obtain the organosilicon monomer; mix the organosilicon monomer and tetramethyltetravinylcyclotetrasiloxane in a mass ratio of 1:6, add 0.3 times the mass of the organosilicon monomer 98wt% sulfuric acid solution, heat to 35 ° C for 6h, and at 4.67x10 -5 MPa under reduced pressure distillation for 40 min, and washed with pure water 6 times to obtain modified polysiloxane;

[0050] (2) epoxy resin and n-butanol were mixed in a mass ratio of 1:60, benzoyl peroxide (2% by weight of epoxy resin) was added, the temperature was raised to 75°C under nitrogen protection, 4-vinyl-benzoic acid methyl ester solution (0.5 times by weight of epoxy resin) was added dropwise at a rate of 1 mL / min, the reaction was continued for 4 h after the addition was completed, the mixture was cooled to 50°C, the pH was adjusted to 7 with 28 wt% ammonia water, and the pre-modified epoxy resin was obtained by distillation under reduced pressure;

[0051] (3) Sodium hydride and solvent are mixed in a mass ratio of 1:8, stirred for 10 minutes at 0°C under nitrogen protection to obtain a sodium hydride solution, and pre-modified epoxy resin, modified polysiloxane, and solvent are mixed in a mass ratio of 1:1.3:12, and added dropwise at a rate of 2.5 mL / min to a sodium hydride solution 8 times the mass of the pre-modified epoxy resin, reacted at 30°C for 90 minutes, and the solvent was removed by vacuum distillation and washed with pure water 3 times, and vacuum dried at 50°C for 12 hours to obtain a modified epoxy resin; pure water, modified epoxy resin, and emulsifier are weighed in a mass ratio of 100:50:10, and the modified epoxy resin and emulsifier are stirred at 70°C and 1000 r / min for 20 minutes, and then pure water is added, and stirring is continued for 30 minutes to obtain a modified epoxy resin emulsion;

[0052] (4) Silica, γ-aminopropyltriethoxysilane, toluene, and triethylamine were mixed in a mass ratio of 1:3:30:0.2, heated to 110°C for reaction for 4 hours, filtered and washed with acetone three times after the reaction was completed to obtain amino silica; amino silica and ethanol were mixed in a mass ratio of 1:40, ultrasonicated for 10 minutes, glutaric anhydride 4 times the mass of amino silica was added, reacted at 37°C for 3 hours, filtered and washed with 0.1M sodium chloride solution three times, and vacuum dried at 50°C for 12 hours to obtain carboxylated silica; carboxylated silica and thionyl chloride were mixed in a mass ratio of 1:20, refluxed at 70°C for reaction for 24 hours, cooled to room temperature, filtered and washed with tetrahydrofuran five times, and dried at 50°C for 12 hours to obtain chlorinated silica; chlorinated silica , 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical, and dichloromethane are mixed in a mass ratio of 1:3:12, and pyridine with a mass of 0.7 times that of the 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical is added dropwise at a rate of 1 mL / min at -5°C. After the addition is completed, the reaction is continued for 8 hours, filtered, washed with pure water for 3 times, and dried at 50°C for 12 hours to obtain nitroxide free radical silicon dioxide; nitroxide free radical silicon dioxide, 3-(3-thienyl)propanal, and tetrahydrofuran are mixed in a mass ratio of 1:3:60, and a 30wt% hydrogen peroxide solution with a volume of 0.4 times that of tetrahydrofuran is added dropwise at 5°C, and then cuprous chloride with a volume of 0.03 times that of the acyl chloride silicon dioxide is added, the temperature is raised to 20°C, and after reacting for 24 hours, the tetrahydrofuran is removed by vacuum rotary evaporation to obtain pre-modified silica;

[0053] (5) Pre-modified silica, thiophene, 3-vinylthiophene, ferric chloride, and chloroform were mixed in a mass ratio of 1:0.12:0.05:6:20, stirred for 8 hours, filtered, and dispersed again in a 1 mol / L hydrochloric acid solution with a mass of 30 times that of the pre-modified silica, stirred for 5 minutes, filtered, washed 3 times with a 1 mol / L hydrochloric acid solution, washed 3 times with pure water, and dried at 50° C. for 12 hours to obtain modified silica;

[0054] (6) The following components were weighed by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 5 parts of modified silica, 24 parts of curing agent, and 0.5 parts of photoinitiator, and the above components were mixed for 3 minutes to obtain a non-flammable water-based aerosol spray paint.

[0055] Comparative Example 1:

[0056] The preparation method of the non-flammable water-based aerosol spray paint of Comparative Example 1 differs from that of Example 2 in that steps (1) to (3) are not included, and step (6) is modified as follows: the following components are weighed by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 4 parts of modified silica, 23 parts of curing agent, and 0.4 parts of photoinitiator; the above components are mixed for 4 minutes to obtain a non-flammable water-based aerosol spray paint.

[0057] Comparative Example 2:

[0058] The preparation method of the non-flammable water-based aerosol spray paint of Comparative Example 2 differs from that of Example 2 in that steps (4) to (5) are not included, and step (6) is modified as follows: the following components are weighed by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 4 parts of modified silica, 23 parts of curing agent, and 0.4 parts of photoinitiator; the above components are mixed for 4 minutes to obtain a non-flammable water-based aerosol spray paint.

[0059] Comparative Example 3:

[0060] The preparation method of the non-flammable water-based aerosol spray paint of Comparative Example 3 differs from that of Example 2 in that step (6) is modified as follows: weigh the following components by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 4 parts of modified silica, and 23 parts of curing agent; mix the above components for 4 minutes to obtain a non-flammable water-based aerosol spray paint.

[0061] Comparative Example 4:

[0062] The preparation method of the non-flammable water-based aerosol spray paint of Comparative Example 4 differs from that of Example 2 in that steps (1) to (5) are not included, and step (6) is modified as follows: the following components are weighed by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 4 parts of silicon dioxide, 23 parts of curing agent, and 0.4 parts of photoinitiator; the above components are mixed for 4 minutes to obtain a non-flammable water-based aerosol spray paint.

[0063] Test Example 1:

[0064] Flame retardant performance test:

[0065] Test method: The non-flammable water-based aerosol spray paint prepared in the embodiment and the comparative example was sprayed on the surface of the horse mouth patch using a paint spray gun, and then placed in a UV curing machine for radiation curing for 4 minutes, the UV lamp power was 400W, the normal working current was 3.5A, and the UV lamp distance was 10cm to obtain a coating with a surface thickness of 14.5μm. The limiting oxygen index was measured using a JF-3 instrument. The results are shown in Table 1.

[0066] Table 1 Flame retardant performance test results

[0067] Limiting oxygen index (%) Limiting oxygen index (%) Example 1 34.7 Comparative Example 1 30.4 Example 2 34.9 Comparative Example 2 26.3 Example 3 34.9 Comparative Example 3 34.6 Comparative Example 4 23.2

[0068] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1, it can be found that the non-flammable water-based aerosol spray paint prepared in the present invention has good flame retardant properties.

[0069] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Examples 2 and 4, indicating that the silicon dioxide modified with γ-aminopropyltriethoxysilane is reacted with maleic anhydride and then chlorinated with thionyl chloride to obtain chlorinated silicon dioxide, and the chlorinated silicon dioxide is reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical and then reacted with 3-(3-thienyl)propionaldehyde to generate an N-alkoxyamine structure. The N-alkoxyamine structure can not only improve the ultraviolet light stability of the material, but also contribute to the improvement of the flame retardant properties of the material.

[0070] Test Example 2:

[0071] Tests for anti-corrosion and anti-aging properties:

[0072] Salt water resistance test: The non-flammable water-based aerosol spray paint prepared in the embodiment and the comparative example is sprayed on the surface of the horse mouth patch using a paint spray gun, and then placed in a UV curing machine for radiation curing for 4 minutes. The UV lamp power is 400W, the normal working current is 3.5A, and the UV lamp distance is 10cm to obtain a coating with a surface thickness of 14.5μm. At 25°C, the coating is placed in a 5wt% sodium chloride solution, and 2 / 3 of the length of each coating is immersed in the sodium chloride solution for 600h, and the appearance of the test coating is observed; before the coating is immersed in the sodium chloride solution, a paraffin and rosin mixture is used for edge sealing, and the edge sealing width is 2.3mm. The paraffin rosin mixture is made by mixing paraffin and rosin in a mass ratio of 1:1. The results are shown in Table 2.

[0073] UV aging resistance test: The non-flammable water-based aerosol spray paint prepared in the embodiment and the comparative example was sprayed on the surface of the horse mouth patch, and then placed in a UV curing machine for radiation curing for 4 minutes, the UV lamp power was 400W, the normal working current was 3.5A, and the UV lamp distance was 10cm to obtain a coating with a surface thickness of 14.5μm. The coating was placed in a UV aging box for irradiation, the temperature in the aging box was 50°C, the irradiation time was 720h, the wavelength of the UV light was 340nm, the lamp power was 40W, the distance between the coating and the light source was 50mm, and the appearance of the coating was observed. The results are shown in Table 2.

[0074] Table 2 Anti-corrosion and anti-aging performance test results

[0075]

[0076]

[0077] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the non-flammable water-based aerosol spray paint prepared by the present invention has good anti-corrosion and anti-ultraviolet aging capabilities.

[0078] The appearance after the salt water resistance test of Examples 1 to 3 is better than that of Comparative Example 4, and the appearance after the UV resistance test of Examples 1 to 3 is better than that of Comparative Example 4, indicating that the modified polysiloxane is obtained by reacting (triethoxysilyl)acetophenone with trimethylchlorosilane and then ring-opening polymerization with tetramethyltetravinylcyclotetrasiloxane. One end of the modified polysiloxane is an acetophenone structure, the main chain contains a carbon-carbon double bond, and the epoxy resin is grafted with 4-vinyl-methyl benzoate. The side chain of the epoxy resin Grafted methyl benzoate structure, methyl benzoate and acetophenone at one end of modified polysiloxane undergo condensation reaction to generate dibenzoylmethane structure, in which there is tautomerism equilibrium between keto form and enol form, and the tautomerism process between these two structures can convert light energy into heat energy or harmless low-energy radiation, thereby effectively absorbing ultraviolet rays and giving the spray paint good anti-ultraviolet aging performance; the low surface tension of polysiloxane can reduce the surface energy of the spray paint, thereby improving its water resistance and thus improving corrosion resistance;

[0079] Secondly, the silicon dioxide modified by γ-aminopropyltriethoxysilane is reacted with maleic anhydride, and then chlorinated with thionyl chloride to obtain chlorinated silicon dioxide. The chlorinated silicon dioxide is reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine nitrogen oxide free radical, and then reacted with 3-(3-thienyl)propionaldehyde to generate an N-alkoxyamine structure. The N-alkoxyamine structure can not only improve the ultraviolet light stability of the material, but also help to improve the flame retardant properties of the material. At the same time, the thiophene structure is also introduced, and then polymerized with thiophene and 3-vinylthiophene on the surface of silicon dioxide to form polythiophene containing double bonds. Polythiophene can form a dense oxide film protective layer on the surface of the metal substrate. This protective film can effectively prevent corrosive ions and solutions from penetrating into the surface of the metal substrate, thereby playing a role of mechanical barrier. This barrier effect can reduce the corrosion rate and extend the service life of the metal substrate.

[0080] Test Example 3:

[0081] Mechanical properties test:

[0082] Test method: The non-flammable water-based aerosol spray paint prepared in the embodiment and the comparative example was sprayed on the surface of the horse mouth patch using a paint spray gun, and then placed in a UV curing machine for radiation curing for 4 minutes. The UV lamp power was 400W, the normal working current was 3.5A, and the UV lamp distance was 10cm to obtain a coating with a surface thickness of 14.5μm. The hardness test was performed using the pencil hardness method in accordance with GB / T6739.2006. The instrument used was a BGD506 trolley-type pencil hardness tester. The results are shown in Table 3.

[0083] Table 3 Mechanical properties test results

[0084] Hardness H(%) Hardness H(%) Example 1 3H Comparative Example 1 2H Example 2 3H Comparative Example 2 2H Example 3 3H Comparative Example 3 1H Comparative Example 4 1H

[0085] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 3, it can be found that the non-flammable water-based aerosol spray paint prepared by the present invention has good mechanical properties.

[0086] The hardness of Examples 1 to 3 is greater than that of Comparative Examples 1 to 4, indicating that the modified epoxy resin emulsion, pure water, modified silica, curing agent, and photoinitiator are mixed to prepare a non-flammable water-based aerosol spray paint; the modified epoxy resin emulsion and modified silica produce secondary crosslinking through double bond free radical polymerization under the action of the photoinitiator and the irradiation of ultraviolet light, thereby generating a denser crosslinking network, which can enhance the mechanical properties of the coating formed by the spray paint.

[0087] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A non-flammable water-based aerosol spray paint, characterized in that: The non-flammable water-based aerosol spray paint is prepared by mixing modified epoxy resin emulsion, pure water, modified silicon dioxide, curing agent and photoinitiator; The modified epoxy resin emulsion is obtained by grafting 4-vinyl-methyl benzoate onto epoxy resin, reacting with modified polysiloxane, and then emulsifying; the modified polysiloxane is obtained by reacting p-(triethoxysilyl)acetophenone with trimethylchlorosilane, and then ring-opening polymerization with tetramethyltetravinylcyclotetrasiloxane; The modified silica is prepared by reacting γ-aminopropyltriethoxysilane-modified silica with maleic anhydride, followed by chlorination with thionyl chloride to obtain chlorinated silica, and then reacting the chlorinated silica with 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical, followed by 3-(3-thienyl)propionaldehyde, and then with thiophene and 3-vinylthiophene to obtain the obtained silica.

2. A method for preparing a non-flammable water-based aerosol spray paint, characterized in that: The method comprises the following preparation steps: (1) Organic silicon monomer and tetramethyltetravinylcyclotetrasiloxane were mixed in a mass ratio of 1:(5-6), 0.2-0.3 times the mass of organic silicon monomer was added with a 98 wt% sulfuric acid solution, the temperature was raised to 35°C and the reaction was carried out for 6 hours. -5 MPa under reduced pressure distillation for 40-50 min, and washing with pure water for 6-8 times to obtain modified polysiloxane; (2) epoxy resin and n-butanol are mixed in a mass ratio of 1:(50-60), benzoyl peroxide of 1%-2% by mass of epoxy resin is added, the temperature is raised to 75-85° C. under nitrogen protection, 4-vinyl-benzoic acid methyl ester solution of 0.3-0.5 times by mass of epoxy resin is added dropwise at a rate of 1 mL / min, the reaction is continued for 4 h after the addition is completed, the mixture is cooled to 50° C., the pH is adjusted to 7-8 with 28wt% ammonia water, and the pre-modified epoxy resin is obtained by distillation under reduced pressure; (3) Sodium hydride and solvent are mixed in a mass ratio of 1:(7-8), stirred for 10-20 min under nitrogen protection at 0-4°C to obtain a sodium hydride solution, a pre-modified epoxy resin, a modified polysiloxane, and a solvent are mixed in a mass ratio of 1:(1.2-1.3):(10-12), and added dropwise at a rate of 2.5 mL / min to a sodium hydride solution 7-8 times the mass of the pre-modified epoxy resin, reacted at 30°C for 90-100 min, the solvent was removed by reduced pressure distillation, and washed with pure water for 3-4 times, and vacuum dried at 50-60°C for 12 h to obtain a modified epoxy resin; pure water, modified epoxy resin, and emulsifier are weighed in a mass ratio of 100:50:10, the modified epoxy resin and emulsifier are stirred at 70°C and 1000 r / min for 20 min, pure water is added, and stirring is continued for 30 min to obtain a modified epoxy resin emulsion; (4) mixing silicon dioxide, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical and dichloromethane in a mass ratio of 1:(2-3):(10-12), adding pyridine in an amount of 0.5-0.7 times the mass of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical dropwise at a rate of 1 mL / min at -5-4°C, continuing the reaction for 8-10 hours after the addition is completed, filtering, washing with pure water 3-4 times, and drying at 50-60°C for 1 hour. 2h to obtain nitroxide free radical silicon dioxide; nitroxide free radical silicon dioxide, 3-(3-thienyl)propionaldehyde, and tetrahydrofuran are mixed uniformly in a mass ratio of 1:(2-3):(50-60), and a 30wt% hydrogen peroxide solution of 0.4 times the volume of tetrahydrofuran is added dropwise at 5-10°C, and then cuprous chloride of 0.03 times the mass of the acyl chloride silicon dioxide is added, the temperature is raised to 20-30°C, and after reacting for 24h, the tetrahydrofuran is removed by vacuum rotary evaporation to obtain pre-modified silicon dioxide; (5) Pre-modified silica, thiophene, 3-vinylthiophene, ferric chloride, and chloroform are mixed in a mass ratio of 1:(0.1-0.12):(0.03-0.05):(5-6):20, stirred for 8-10 hours, filtered, and dispersed again in a 1 mol / L hydrochloric acid solution of 20-30 times the mass of the pre-modified silica, stirred for 5-10 minutes, filtered, washed 3-4 times with a 1 mol / L hydrochloric acid solution, washed 3-4 times with pure water, and dried at 50-60° C. for 12 hours to obtain modified silica; (6) Weigh the following components by mass: 100 parts of modified epoxy resin emulsion, 10 parts of pure water, 3-5 parts of modified silica, 22-24 parts of curing agent, and 0.3-0.5 parts of photoinitiator, and mix the above components to obtain non-flammable water-based aerosol spray paint.

3. The method for preparing a non-flammable water-based aerosol spray paint according to claim 2, characterized in that: The preparation method of the organosilicon monomer in step (1) is as follows: trimethylchlorosilane, p-(triethoxysilyl)acetophenone and hydroquinone are mixed in a mass ratio of 1:(0.9-1.0):(0.03-0.05), ethanol 2.3-2.5 times the mass of trimethylchlorosilane is added dropwise at a rate of 2.5 mL / min, and after the addition is completed, stirring is performed at 20° C. for 30 min, and then pure water 0.5 times the mass of ethanol is added dropwise at a rate of 2.5 mL / min, and after the addition is completed, the temperature is raised to 50° C., and pure water 0.5 times the mass of ethanol is continued to be added dropwise at a rate of 2.5 mL / min. After the addition is completed, the temperature is kept warm for 10 h, and the mixture is allowed to stand for 40-50 min. The water layer is discarded and the organic phase is washed 7-8 times with pure water, and the mixture is stirred at 1.33x10 -3 MPa, distill under reduced pressure at 100-110°C, collect the fractions, and obtain the organosilicon monomer.

4. The method for preparing a non-flammable water-based aerosol spray paint according to claim 2, characterized in that: The epoxy resin model of step (2) is E-44; the 4-vinyl-methyl benzoate solution is obtained by mixing 4-vinyl-methyl benzoate and n-butanol in a mass ratio of 1:

10.

5. The method for preparing a non-flammable water-based aerosol spray paint according to claim 2, characterized in that: The solvent in step (3) is a mixture of dimethyl sulfoxide and tetrahydrofuran in a volume ratio of 1:1; and the emulsifier is OP-10.

6. The method for preparing a non-flammable water-based aerosol spray paint according to claim 2, characterized in that: The preparation method of the acylated silicon dioxide in step (4) is as follows: silicon dioxide, γ-aminopropyltriethoxysilane, toluene, and triethylamine are mixed in a mass ratio of 1: (2-3): (20-30): (0.1-0.2), heated to 110° C. for reaction for 4-5 hours, and after the reaction, filtered and washed with acetone for 3-4 times to obtain amination silicon dioxide; amination silicon dioxide and ethanol are mixed in a mass ratio of 1: (30-40), ultrasonicated for 10-20 minutes, and added The mass of aminosilica is 3-4 times that of glutaric anhydride, reacted at 37°C for 3-4h, filtered and washed with 0.1M sodium chloride solution for 3-4 times, and vacuum dried at 50-60°C for 12h to obtain carboxylated silica, carboxylated silica and thionyl chloride are mixed at a mass ratio of 1:20, refluxed at 70°C for 24h, cooled to room temperature, filtered, washed with tetrahydrofuran for 5-6 times, and dried at 50-60°C for 12h to obtain acyl chloride silica.

7. The method for preparing a non-flammable water-based aerosol spray paint according to claim 6, characterized in that: The silicon dioxide model is VK-SP30S.

8. The method for preparing a non-flammable water-based aerosol spray paint according to claim 2, characterized in that: The curing agent model in step (6) is T-403; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone.

9. A method for using the non-flammable aerosol spray paint prepared according to the method for preparing the non-flammable water-based aerosol spray paint according to any one of claims 2 to 8, the method of use comprising: using a paint spray gun to spray the non-flammable water-based aerosol spray paint on the surface of a tinplate sheet, and then placing the non-flammable water-based aerosol spray paint in a UV curing machine for curing. The non-flammable water-based aerosol spray paint needs to be used up within 4 hours.

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