A preparation method of in-situ synthesized zinc oxide polyurethane emulsion

Abstract

The present invention belongs to the technical field of zinc oxide materials, and particularly relates to a preparation method of in-situ synthesized zinc oxide polyurethane emulsion. The present invention uses an inorganic divalent zinc salt solution of zinc acetate or zinc nitrate with a simple preparation method and wide raw material sources as the precursor of zinc oxide. By utilizing a large number of plant active ingredients contained in plant polyhydroxy compounds, such as flavonoids, saponins, and fatty acids, etc., they combine with dissolved oxygen in water to form nano zinc oxide. The present invention utilizes in-situ synthesized zinc oxide polyurethane emulsion. The plant polyhydroxy compound reacts with isocyanate as a reaction monomer to generate polyurethane and also acts as a reducing agent to in-situ generate zinc oxide, which is uniformly dispersed in the emulsion, avoiding particle agglomeration caused by directly adding filled zinc oxide in the past. At the same time, zinc oxide is uniformly dispersed, the emulsion coating has a thin and flat thickness, good mechanical properties, and is not prone to embrittlement.

Description

Technical Field

[0001] The present invention belongs to the technical field of zinc oxide materials, and in particular to a preparation method of in-situ synthesized zinc oxide polyurethane emulsion. Background Art

[0002] Emulsion products containing zinc oxide are applied in many fields. For example, people used to apply zinc oxide emulsion on the nose and cheeks to prevent damage caused by sunlight. In past daily production, people directly blended solid nano zinc oxide or zinc oxide powder in the emulsion. However, due to the different surface or interfacial properties of zinc oxide and the matrix, i.e., organic polymers or resins, the compatibility is poor, and it is difficult to disperse evenly in the matrix. Direct or excessive filling often easily leads to a decline in certain mechanical properties of the material and causes disadvantages such as embrittlement, and the application effect is poor. The inventor of the present invention has been researching nano zinc oxide since 1998, and the research results have been applied for a number of invention patents to the Chinese Patent Office. Among them, CN113621164B uses in-situ synthesized zinc oxide emulsion foaming material, which acts as a foaming agent while generating zinc oxide. The precursor basic zinc carbonate emulsion of zinc oxide in the emulsion is evenly dispersed, avoiding particle agglomeration caused by adding and filling zinc oxide in the past. At the same time, when uniformly distributed zinc oxide is generated, the escape of gas is also uniform, and the emulsion expands evenly, forming pores of uniform size, better uniform foaming. It uses the decomposition of basic zinc carbonate to generate zinc oxide, but this method is only limited to the emulsion foaming treatment on the surface of high-temperature resistant fiber fabrics, and the emulsion components are limited to high-temperature resistant polymer emulsions such as polyimide emulsion and polytetrafluoroethylene emulsion, and the use has certain limitations. Those skilled in the art urgently need to develop a preparation method and application of in-situ synthesized zinc oxide polyurethane emulsion to meet the existing market demands and performance requirements. Summary of the Invention

[0003] Aiming at the above problems, the present invention aims to provide a preparation method of in-situ synthesized zinc oxide polyurethane emulsion.

[0004] A preparation method of in-situ synthesized zinc oxide polyurethane emulsion includes the following steps:

[0005] a. React polymer polyol, plant polyhydroxy compound with isocyanate to prepare polyurethane prepolymer. Specifically, weigh 35 - 40 parts by mass of the dehydrated polymer polyol and 7 - 8 parts of the plant polyhydroxy compound and 10 - 15 parts by mass of diisocyanate into a reaction kettle after vacuum dehydrating the plant polyhydroxy compound and the polymer polyol at 90 - 100 °C and 0.1 MPa for 0.5 - 1 h, mix and stir, add 0.02 - 0.04 parts by mass of catalyst when the temperature is raised to 75 - 80 °C, and keep warm and stir for reaction for 2 - 2.5 h to obtain the polyurethane prepolymer;

[0006] Under the catalysis, plant sources such as bamboo materials can be liquefied into plant polyhydroxy compounds in a liquefying agent.

[0007] For example, castor oil is a fatty oil extracted from the seeds of the castor plant, a plant of the Euphorbiaceae family. In the past, it could be used in medicine to treat constipation, sores, burns, etc.

[0008] For another example, bamboo extracts contain physiological active substances such as flavonoids, phenolic acids, lactones, polysaccharides, and trace elements, and have the effects of scavenging active oxygen free radicals, blocking nitrosation reactions, and reducing blood lipids.

[0009] b. Weigh an inorganic divalent water-soluble zinc salt, add deionized water, and ultrasonically dissolve it to obtain a zinc oxide precursor solution;

[0010] c. In the polyurethane prepolymer, add a mixture of 2 - 4 parts by mass of ethanol and 120 - 140 parts of acetone, add the zinc oxide precursor solution and an emulsifier, and continue to stir at 50 - 60 °C for 0.5 - 1 hour for emulsification. Then, evaporate acetone at normal pressure at 94 °C until no odor is detected, cool to room temperature, and add water to dilute to the required concentration to obtain an in-situ synthesized zinc oxide polyurethane emulsion.

[0011] Further, the polymer polyol is at least one of polytetrahydrofuran diol and polypropylene glycol, and the molecular weight is 100 - 3000.

[0012] Further, the diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate.

[0013] Further, the concentration of the zinc oxide precursor solution is 0.25 - 0.5 mol / L.

[0014] Further, the solid content of the in-situ synthesized zinc oxide polyurethane emulsion in step c is 25% - 50%, the emulsifier is sodium 2-(2-aminoethylamino)ethanesulfonate or sodium oleyl ethyl sulfonate, and the emulsifier accounts for 0.5% - 0.8% of the mass of the in-situ synthesized zinc oxide polyurethane emulsion.

[0015] Further, the plant polyhydroxy compound includes one of bamboo waste liquefied polyhydroxy compounds and castor oil polyols.

[0016] Further, the inorganic divalent water-soluble zinc salt in step b is zinc nitrate or zinc acetate.

[0017] Further, the catalyst in step a is one of dibutyltin dilaurate and stannous octoate.

[0018] The mechanism of in-situ synthesis of nano-zinc oxide from plant polyhydroxy compounds is as follows:

[0019]

[0020] Advantages of the present invention:

[0021] In actual production, the inventor attempted to use nano-zinc oxide to replace ordinary zinc oxide, but the drawback of agglomeration has not been effectively solved. There are also a large number of complex and cumbersome zinc oxide surface modification method technologies in the prior art, but the steps are cumbersome and the cost is relatively high.

[0022] In the daily production practice of zinc oxide polyurethane emulsion, it was accidentally found that in a certain batch of polyurethane emulsion, the coating formed on the substrate had a thin thickness and a very flat surface effect. After gradually investigating, it was found that due to an operator's mistake, the precursor salt solution that was not yet zinc oxide was added to the preparation process of the polyurethane emulsion instead of the aqueous suspension of nano-zinc oxide that should have been added. And this phenomenon occurs only when there is a plant polyhydroxy compound that itself serves as a polyol monomer component to synthesize polyurethane. After many practices, the above operation formed the preparation process of in-situ synthesized zinc oxide polyurethane emulsion.

[0023] The present invention uses a polymer polyol, a plant polyhydroxy compound and an isocyanate to react to prepare a polyurethane prepolymer, and uses a zinc oxide precursor solution for emulsification. The plant polyhydroxy compound reacts with the isocyanate as a reaction monomer to form polyurethane, and also acts as a reducing agent to in-situ generate zinc oxide. The plant polyhydroxy compound contains a large number of plant active ingredients, such as flavonoids, saponins and fatty acids, etc. These compounds often act as antioxidants to neutralize active oxygen, free radicals and chelate metals. Especially polyhydroxy flavonoids can be used as masking agents and biological reducing agents to promote the formation of nanoparticles. Zn(Ⅱ) interacts with the phytochemical molecules in the extract and is reduced to Zn(0). And due to the presence of active molecules, the aggregation of Zn(0) can also be prevented. Finally, Zn(0) combines with the dissolved oxygen in water to in-situ synthesize nano-zinc oxide, which is uniformly dispersed in the polyurethane emulsion.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] In the polyurethane emulsion formulation system, in order to better improve the various properties of the emulsion and reduce costs, fine powders or ultrafine powder fillers are often added. However, due to the large specific surface area of the ultrafine powder fillers, they are prone to agglomeration and are extremely easy to adhere to each other, forming agglomerates. It is very difficult to fluidize normally like ordinary powders during use, and the conveying pipeline will often be blocked. The interaction force between fine powder particles is mainly van der Waals force, and almost all existing ultrafine powders are prepared by ultrafine grinding, with high production costs and dust pollution. In previous production practices, the preparation of polyurethane emulsion containing zinc oxide was also carried out by adding it additionally and mechanically stirring to distribute zinc oxide into the polyurethane emulsion, but the drawback of agglomeration has still not been solved.

[0026] The invention adopts an inorganic divalent zinc salt solution of zinc acetate or zinc nitrate, which has a simple preparation method and a wide source of raw materials, as a precursor of zinc oxide, and utilizes a large amount of plant active ingredients contained in plant polyols, such as flavonoids, saponins and fatty acids, etc., to combine with dissolved oxygen in water to form nano zinc oxide. The invention utilizes in-situ synthesized zinc oxide polyurethane emulsion, and the plant polyols are used as reaction monomers to react with isocyanate to generate polyurethane, and also play the role of a reducing agent, and in-situ generates zinc oxide, which is evenly dispersed in the emulsion, thereby avoiding the agglomeration of particles caused by the direct addition of filled zinc oxide in the past, and at the same time, the zinc oxide is evenly dispersed. After adding a foaming agent, the method and product of the invention can also be used for foaming treatment of the surface of cotton, polyester and other fibers that are not resistant to high temperatures. After drying and baking, the pattern is foamed and thickened, presenting a three-dimensional state. At the same time, due to the in-situ generation of zinc oxide nanoparticles, the film layer formed by the emulsion, or the surface foaming layer has certain antibacterial, photosensitive degradation and other properties, and can achieve a coating appearance that is better than ordinary powder and more beautiful, and reduce production costs. DETAILED DESCRIPTION

[0027] The present invention is described below with specific examples, but is not intended to be limiting of the present invention. Example 1

[0028] Prepare raw materials: castor oil polyol YC-CY-210 of Liaoning Chuangye Bio-New Materials Technology Co., Ltd., 200 parts of 1000 polypropylene glycol, 35 parts of YC-CY-210 castor oil polyol, catalyst Hengguang T-12 dibutyltin dilaurate, 75 parts of Yinguang Chemical TDI-100 toluene diisocyanate, 2 parts of ethanol, and 120 parts of acetone.

[0029] The first step is to weigh zinc acetate, add deionized water, and ultrasonically dissolve it to obtain a zinc oxide precursor solution, wherein the concentration of the zinc oxide precursor solution is 0.5 mol / L;

[0030] Step 2: Prepare polyurethane prepolymer by reacting polypropylene glycol, plant polyol-castor oil polyol and isocyanate. Dehydrate the plant polyol and polymer polyol under vacuum at 100°C and 0.1MPa for 1h, and then heat to 60°C to dissolve the plant polyol in polypropylene glycol. When the temperature rises to 80°C, add 0.04 parts by mass of catalyst T-12, and then slowly drop TDI-100 toluene diisocyanate, and react for 2h under heat preservation and stirring to obtain polyurethane prepolymer.

[0031] Step 3: Add a mixture of ethanol and acetone to the polyurethane prepolymer. Then add the zinc oxide precursor solution and the emulsifier sodium oleoyl ethyl sulfonate, and continue to stir at 7000 rpm for 0.5 hours at 50 °C for emulsification. The emulsifier accounts for 0.8% of the mass of the in-situ synthesized zinc oxide polyurethane emulsion. Then distill off acetone at normal pressure at 94 °C until no odor is detected, and cool to room temperature to obtain an in-situ synthesized zinc oxide polyurethane emulsion with a solid content of 50%.

[0032] Product: An opalescent emulsion with a solid content of 50%, pH 6, without mechanical impurities or coagulants, and an ash content of 15%. The storage stability at 50 °C is normal, without hard lumps, flocs, obvious stratification or skin formation. The freeze-thaw stability after 3 cycles is without hard lumps or flocculation. The dilution stability at 1:12 is without flocculation and can form a uniform liquid. The mechanical stability is without demulsification and without obvious flocs.

[0033] Control Example 1

[0034] Compared with Example 1, in Step 3 of this control example, instead of adding the zinc oxide precursor solution, water and zinc oxide JH-1 produced by Jinhua Zinc Oxide Factory are added, where the zinc oxide accounts for 15% of the mass of the emulsion, and the remaining steps are the same as those in Example 1.

[0035] Product: An opalescent emulsion with a solid content of 20%, pH 6, without mechanical impurities but with a small amount of coagulants. The storage stability at 50 °C has a little hard lumps, a little flocs, a small amount of stratification and skin formation. The freeze-thaw stability after 3 cycles is without hard lumps or flocculation. The dilution stability at 1:12 is without flocculation and can form a uniform liquid. The mechanical stability is without demulsification and without obvious flocs. Example 2

[0036] Castor oil polyol YC-CY-210 from Liaoning Chuangye Bio-New Materials Technology Co., Ltd., 200 parts of PTG company's PTMEG-1000 polytetrahydrofuran diol, 35 parts of YC-CY-310 castor oil polyol, Kosmos 29 stannous octoate catalyst, 50 parts of isophorone diisocyanate, 4 parts of ethanol, and 140 parts of acetone.

[0037] Step 1: Weigh zinc acetate, add deionized water, and dissolve it by ultrasonic to obtain a zinc oxide precursor solution. The concentration of the zinc oxide precursor solution is 0.25 mol / L.

[0038] Step 2: React polytetrahydrofuran diol, plant polyhydroxy compound - castor oil polyol with isocyanate to prepare polyurethane prepolymer. Under the conditions of 90°C and 0.1 MPa, vacuum dehydrate the plant polyhydroxy compound and polymer polyol for 0.5 h, then heat to 60°C to dissolve the plant polyhydroxy compound in tetrahydrofuran diol. When the temperature is raised to 75°C, add 0.02 parts by mass of catalyst, and then slowly dropwise add isophorone diisocyanate, keep warm and stir for reaction for 2.5 h to obtain the polyurethane prepolymer;

[0039] Step 3: Add a mixture of ethanol and acetone to the polyurethane prepolymer, add zinc oxide precursor solution and emulsifier sodium oleyl ethyl sulfonate, and continue to stir and emulsify at 50°C at 8000 rpm for 0.5 h. The emulsifier accounts for 0.5% of the mass of the in-situ synthesized zinc oxide polyurethane emulsion. Then distill off acetone at normal pressure at 94°C until no odor is detected, and cool to room temperature to obtain the in-situ synthesized zinc oxide polyurethane emulsion with a solid content of 25%.

[0040] Product: An opalescent emulsion with a solid content of 25%, pH 6, without mechanical impurities and coagulants in appearance, with normal storage stability at 50°C, no hard lumps, no flocculants, no obvious delamination and crusting, no hard lumps and no flocculation after 3 freeze-thaw stabilities, 1:12 dilution stability, no flocculation, and can form a uniform liquid; Mechanical stability: no demulsification, no obvious flocculants. Example 3

[0041] Refer to the preparation method of plant polyhydroxy compound in (Liu Yuhuan, Gao Longlan, Peng Hong, Zhou Houde, Ruan Rongsheng. Study on the liquefaction of bamboo waste to prepare polyhydroxy compound [J]. Modern Chemical Industry, 2008(S2):214 - 217.). The bamboo material is the bamboo material of Linshantou Longtai, with water 10.13%, ash 1.60%, cellulose 46.34%, hemicellulose 18.76%, lignin 23.68%, and benzene ethanol extract 9.50%. The liquefaction conditions are: temperature 160°C, sulfuric acid dosage 3%, bamboo chip addition amount 30%, reaction for 120 min, the liquefaction efficiency reaches 95%, the hydroxyl value of the liquefied product polyhydroxy compound is 205 mg(KOH) / g, and the viscosity is 890 mPa•s.

[0042] Prepare raw materials: 175 parts of PTMEG-1000 polytetrahydrofuran diol from PTG company, 27.0 parts of liquefied product polyhydroxy compound, T-12 dibutyltin dilaurate catalyst, 50 parts of TPA-100 hexamethylene diisocyanate, 3 parts of ethanol, and 130 parts of acetone.

[0043] Step 1: Weigh zinc nitrate, add deionized water, and ultrasonically dissolve to obtain zinc oxide precursor solution. The concentration of the zinc oxide precursor solution is 0.25 mol / L;

[0044] Step 2: Prepare a polyurethane prepolymer through the reaction of polypropylene glycol and plant polyhydroxyl compounds - bamboo waste liquefied polyhydroxyl compounds with isocyanate. Under the conditions of 100°C and 0.1 MPa, dehydrate the plant polyhydroxyl compounds and polymer polyols under vacuum for 0.5 h, then heat to 60°C to dissolve the plant polyhydroxyl compounds in polytetrahydrofuran diol. When the temperature is raised to 76°C, add 0.04 parts by mass of a catalyst, and then slowly dropwise add hexamethylene diisocyanate. Keep the temperature and stir for 2.2 h to obtain the polyurethane prepolymer;

[0045] Step 3: When the viscosity of the polyurethane prepolymer is measured to be about 84000 CPS, add a mixture of ethanol and acetone, add a zinc oxide precursor solution and an emulsifier sodium 2-(2-aminoethylamino)ethanesulfonate, and continue to stir and emulsify at 55°C at 6000 rpm for 0.7 h. The emulsifier accounts for 0.6% of the mass of the in-situ synthesized zinc oxide polyurethane emulsion. Then, distill off acetone at normal pressure at 94°C until no odor is detected, and cool to room temperature to obtain an in-situ synthesized zinc oxide polyurethane emulsion with a solid content of 25%.

[0046] Product: An opalescent blue-tinged translucent emulsion with a solid content of 25%, pH 6, without mechanical impurities and coagulants, and an ash content of 7.5%.

[0047] The storage stability at 50°C is normal, the film hardness is 45.8 Shore A, the film tensile strength is 8.9 MPa, and the film elongation at break is 311.4%.

[0048] Control Example 2

[0049] Compared with Example 3, in this control example, in Example 3, the zinc oxide precursor solution is not added, and nano zinc oxide JH-1 from Hanshan County Jinhua Zinc Oxide Factory with the same mass content is added, and emulsification is carried out according to the same steps to obtain a 25% polyurethane emulsion.

[0050] Product: An opalescent blue-tinged translucent emulsion with a solid content of 20%, pH 6, without mechanical impurities and a small amount of coagulants.

[0051] The storage stability at 50°C is normal, the film hardness is 46 Shore A, the film tensile strength is 8.2 MPa, and the film elongation at break is 304.5%.

[0052] Among them, the film tensile strength, film elongation at break, and film hardness are tested according to the provisions of QB / T2415. Example 4

[0053] Prepare a foamed coating using the in-situ synthesized zinc oxide polyurethane emulsion:

[0054] Add 4% by mass of the strong foaming polyurethane emulsion foaming agent AFCONA-7380 to the in-situ synthesized zinc oxide polyurethane emulsion obtained in Example 3 to foam the polyurethane emulsion, which can form delicate and uniform pores and maintain the high stability of the foam. Use manual table screen printing with a screen specification of 120 mesh. After the fabric is printed and dried or air-dried, use the YP500 flat ironing foaming process with a pressure of 100 kg / cm2, a temperature of 120 °C, and a time of 4 s.

[0055] After the product is foamed, the surface is smooth and even, and the fastness is good.

[0056] Note: The test conditions are as follows: the temperature in the laboratory is 23 °C and the humidity is 50%. The specimens need to be conditioned before the test, with a placement time of 6 h. Analytical pure reagents and grade 3 water specified in GB / T 6682 are used for the test. For the appearance, use a glass rod to evenly and thinly apply the specimen on a clean glass plate and check by visual method. The mass fraction of non-volatile matter is determined at a constant temperature of 150 °C and a drying time of 60 min, and the other tests are carried out according to the method specified in 5.2 of GB / T 11175-2002; the pH value is determined according to the method specified in GB / T8325; the freeze-thaw stability is determined according to the method specified in 5.5 of GB / T 11175-2002. The storage stability is determined according to the method specified in 5.6 of GB / T 11175-2002. The dilution stability is determined according to the method specified in 5.7 of GB / T11175-2002. The mechanical stability is determined according to the method specified in 5.8 of GB / T 11175-2002.

Claims

1. Preparation method of in-situ synthesized zinc oxide polyurethane emulsion, characterized in that, it comprises the following steps: a. React polymer polyol, plant polyhydroxy compound with isocyanate to prepare polyurethane prepolymer. After vacuum dehydrating the plant polyhydroxy compound and polymer polyol at 90 - 100 °C and 0.1 MPa for 0.5 - 1 h, weigh 35 - 40 parts by mass of the dehydrated polymer polyol, 7 - 8 parts of the plant polyhydroxy compound and 10 - 15 parts by mass of diisocyanate, mix and stir in a reaction kettle. When the temperature is raised to 75 - 80 °C, add 0.02 - 0.04 parts by mass of catalyst, keep warm and stir for reaction for 2 - 2.5 h to obtain the polyurethane prepolymer. The polymer polyol is at least one of polytetrahydrofuran diol and polypropylene glycol, with a molecular weight of 100 - 3000. The diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate. The plant polyhydroxy compound includes one of bamboo waste liquefied polyhydroxy compound and castor oil polyol; b. Weigh an inorganic divalent water-soluble zinc salt, add deionized water, and ultrasonically dissolve to obtain a zinc oxide precursor solution, and the concentration of the zinc oxide precursor solution is 0.25 - 0.5 mol / L; c. In the polyurethane prepolymer, add a mixture of 2 - 4 parts by mass of ethanol and 120 - 140 parts of acetone, add the zinc oxide precursor solution and emulsifier, and continue to stir and emulsify at 50 - 60 °C for 0.5 - 1 h. Then distill off acetone at normal pressure at 94 °C until no odor is detected. Cool to room temperature, and dilute with water to the required concentration to obtain the in-situ synthesized zinc oxide polyurethane emulsion. The solid content of the in-situ synthesized zinc oxide polyurethane emulsion in step c is 25% - 50%. The emulsifier is sodium 2-(2-aminoethylamino)ethanesulfonate or sodium oleate, and the emulsifier accounts for 0.5% - 0.8% of the mass of the in-situ synthesized zinc oxide polyurethane emulsion.

2. The preparation method of in-situ synthesized zinc oxide polyurethane emulsion according to claim 1, characterized in that, the inorganic divalent water-soluble zinc salt in step b is zinc nitrate or zinc acetate.

3. The preparation method of in-situ synthesized zinc oxide polyurethane emulsion according to claim 1, characterized in that, the catalyst in step a is one of dibutyltin dilaurate and stannous octoate.

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