Calcium stearate emulsion as well as preparation method and application thereof

Abstract

The invention relates to the technical field of calcium stearate, and particularly discloses a calcium stearate emulsion and a preparation method and application thereof.The preparation method comprises the steps that stearic acid is heated to be in a molten state, calcium hydroxide is added, stirring and mixing are conducted, deionized water, a silicon dioxide-based compound emulsifier, a defoaming agent and a dispersing agent are added, stirring and mixing are conducted, cooling is conducted, and the calcium stearate emulsion is obtained; the emulsion is prepared by taking water as a dispersion medium, the emulsion is green and environment-friendly, the used silicon dioxide-based composite emulsifier is stable in structure and has amphipathicity, a hydrophobic part can interact with calcium stearate particles, and a hydrophilic part is in contact with water, so that a stable adsorption layer is formed on an emulsion interface, and the effects of emulsifying and stabilizing the emulsion are achieved; the prepared calcium stearate emulsion is excellent in dispersity, has a stable emulsion form, and can be used as an auxiliary agent in rubber processing to improve the flowability and processability of rubber and improve the physical properties and quality stability of rubber products.

Description

Technical Field

[0001] The invention relates to the technical field of calcium stearate, in particular to a calcium stearate emulsion and a preparation method and application thereof. Background Art

[0002] Calcium stearate is a metal soap compound formed by stearic acid and calcium ions through coordination bonds. The hydrophobic long carbon chain and the hydrophilic calcium ion end in its molecular structure have amphiphilic characteristics, which give it excellent lubricity, dispersibility and thermal stability. However, calcium stearate itself is a water-insoluble metal soap surfactant (HLB value is about 5 to 8). Direct use of calcium stearate solid powder is prone to uneven dispersion in polymer matrices such as rubber and plastics, resulting in interface defects. There is also a problem of powder dust, which threatens production safety.

[0003] In industrial production, calcium stearate is generally converted into a stable emulsion system with controllable particle size through water-based emulsification technology, thereby achieving hydrophilic modification of hydrophobic materials. Calcium stearate emulsion is gradually replacing traditional powder products and becoming the mainstream form due to its water-based, low toxicity and strong processing adaptability. In particular, the demand for its application in the field of rubber processing has increased significantly. In particular, in the production of rubber products such as tires, seals, rubber tubes and conveyor belts, calcium stearate emulsion can be used as a plasticizer, lubricant, dispersant and filler to improve the processing performance and physical and mechanical properties of rubber products, prevent rubber from agglomerating, and increase the life of rubber products.

[0004] Chinese patent application CN118359848A discloses a preparation method of calcium stearate emulsion, comprising the following steps: S1, dispersing stearic acid in water to form a first dispersion system; S2, adding calcium oxide into water to react and form a second dispersion system; S3, adding the second dispersion system into the first dispersion system in multiple times, adding a light stabilizer to the emulsion after the reaction is completed, and adding a light stabilizer to the calcium stearate emulsion to improve the light stability and extend its service life, but the particle size in the emulsion is large and the dispersion uniformity is poor. Chinese patent application CN109778592A discloses a water-soluble calcium stearate emulsion and its application, the emulsion adopts a polyoxyethylene ether and sodium sulfonate compound, has excellent emulsification, can enhance the dispersion of calcium stearate in water, increase the solid content, reduce the viscosity, and has good dispersibility, but the emulsion has poor thermal stability.

[0005] Therefore, it is of great significance to provide a calcium stearate emulsion with excellent dispersibility and stability by optimizing the emulsifier system, improving the dispersion process and enhancing functionality. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the deficiencies in the prior art, the present invention provides a calcium stearate emulsion and a preparation method and application thereof, which solve the problems of poor stability and poor dispersibility of the calcium stearate emulsion and provide a calcium stearate emulsion with excellent thermal stability.

[0008] (II) Technical solution

[0009] In order to achieve the above object, the present invention discloses a method for preparing a calcium stearate emulsion, comprising the following steps:

[0010] Step 1, ultrasonically disperse nano-silica into an ethanol solution, and after uniform dispersion, add γ-methacryloxypropyltrimethoxysilane, adjust the pH to 4 with a hydrochloric acid solution, stir and mix, react, and after the reaction is completed, filter, wash with anhydrous ethanol and deionized water, and vacuum dry at 60° C. for 12 hours to obtain modified silica;

[0011] Step 2: ultrasonically disperse the modified silica in N,N-dimethylformamide, and after uniform dispersion, add butylated acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator, stir and mix, react, and after the reaction is completed, cool, filter, wash with anhydrous ethanol, and dry at 60° C. for 6 hours to obtain a silica-based composite emulsifier;

[0012] Step 3: Heat stearic acid to a molten state, add calcium hydroxide, stir and mix, react, add deionized water after the reaction is completed, heat up, add a silica-based composite emulsifier, a defoamer, and a dispersant, adjust the pH value to 8, stir and mix, mix evenly, and slowly cool to obtain a calcium stearate emulsion.

[0013] Preferably, the ethanol solution in step 1 is a 75%wt ethanol aqueous solution.

[0014] Preferably, in the step 1, the mass ratio of nano-silica, ethanol solution and γ-methacryloxypropyltrimethoxysilane is 100:(3800-4500):(18-30).

[0015] Preferably, the reaction temperature in step 1 is 70-80° C., and the reaction time is 5-8 h.

[0016] Preferably, in the step 2, the mass ratio of modified silica, N,N-dimethylformamide, butylated acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator is (9-16):(750-950):(5-8):100:(35-48):(12-20):(7-10):(1-2).

[0017] The maleic acid monoesterified-β-cyclodextrin in step 2 is prepared according to the preparation method of maleic acid monoesterified-β-cyclodextrin in “Chen Pengfei, Song Hang, Li Fulin, Tang Mengyu, Zhou Lu, Preparation and performance study of magnetic nanoparticles modified with maleic acid monoesterified-β-cyclodextrin”.

[0018] Preferably, the reaction temperature in step 2 is 65-75° C., and the reaction time is 6-8 h.

[0019] Preferably, the initiator in step 2 is selected from any one of ammonium persulfate, potassium persulfate and benzoyl peroxide.

[0020] Preferably, in step three, the stearic acid is heated to 70-80° C. to melt.

[0021] Preferably, in step three, the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, defoamer and dispersant is (300-320):100:(2100-2400):(95-120):(0.5-1):(1-3).

[0022] Preferably, the reaction time in step 3 is 1.5-3 h, and the stirring speed during the reaction is 350-450 r / min.

[0023] Preferably, the temperature after heating in step 3 is 80-90° C., the stirring and mixing time is 1-2 h, and the stirring and mixing rate is 1800-2400 r / min.

[0024] Preferably, the defoaming agent in step three is a water-soluble silane defoaming agent.

[0025] Furthermore, the defoaming agent is polydimethylsiloxane.

[0026] The dispersant in step three includes any one of alkylphenol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether and sodium polyacrylate.

[0027] Preferably, the calcium stearate emulsion is prepared by the preparation method of the calcium stearate emulsion.

[0028] Preferably, the calcium stearate emulsion is used in rubber.

[0029] (III) Beneficial technical effects

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) In the present invention, γ-methacryloxypropyltrimethoxysilane is used to modify nano-silica, and alkenyl groups are introduced on the surface of nano-silica to obtain modified silica. Under the action of an initiator, the modified silica, butylated acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, and polyethylene glycol decompose to generate free radicals, which initiate free radical polymerization of the monomers to obtain a silica-based composite emulsifier, and a large number of active groups are introduced during the reaction. Stearic acid is heated to a molten state and reacts with calcium hydroxide to generate calcium stearate. The silica-based composite emulsifier is used as an emulsifier, and a defoamer and a dispersant are added. The mixture is stirred and mixed in a deionized water solvent, and the mixture is slowly cooled after being evenly mixed to obtain a calcium stearate emulsion.

[0032] (2) The modification of nano-silica in the present invention can effectively avoid the agglomeration of nano-silica, and can utilize its steric hindrance effect to prevent particle aggregation. The cavity structure of butylated monoester-β-cyclodextrin has excellent inclusion properties, and the surface contains active groups, which can effectively enhance the interaction between the emulsifier and calcium stearate and other components, and improve the stability and dispersibility of the emulsion. Acrylic acid and its ester monomers in the composite emulsifier have a good balance of hydrophilicity and lipophilicity, which helps the dispersion and stability of the emulsifier in stearic acid and water. Maleic anhydride can further enhance the reactivity and cross-linking ability of the emulsifier, forming an emulsifier molecule with a hydrophilic-lipophilic balance. Polyethylene glycol can enhance the flexibility and stability of the emulsifier molecule through its long chain structure, thereby improving the fluidity and wettability of the emulsion and promoting the dispersibility of other components.

[0033] (3) The silica-based composite emulsifier prepared in the present invention has a stable structure and is amphiphilic, containing both a hydrophilic segment and a hydrophobic segment. The hydrophobic portion can interact with the calcium stearate particles, while the hydrophilic portion contacts the aqueous phase, thereby forming a stable adsorption layer at the emulsion interface, which plays a role in emulsifying and stabilizing the emulsion. The emulsifier can be evenly dispersed in the emulsion, and further, it also helps the calcium stearate particles to be evenly dispersed in the aqueous phase, forming a stable interfacial film in the calcium stearate emulsion system, and preventing the aggregation and sedimentation of the emulsion particles. Modified silica, as an inorganic skeleton, can delay the thermal motion of the polymer chain, and the anhydride group of maleic anhydride forms a coordination bond with calcium stearate to enhance thermal stability. The inorganic-organic composite emulsification system can effectively enhance the heat resistance and mechanical strength of the emulsion. The composite emulsifier contains a large number of active functional groups, which can interact with the calcium stearate particles and the aqueous phase, adsorb on the surface of the calcium stearate particles, form a charged layer or a steric hindrance layer, reduce the mutual attraction between the particles, and prevent the particles from agglomerating, so that the emulsion has good dispersibility, ensure the uniform particle size of the calcium stearate particles in the emulsion, improve the adhesion and adhesion of the emulsion, improve the product quality, and make the emulsion less likely to stratify and demulsify during storage and use. The various components in the composite emulsifier work synergistically to reduce interfacial tension and improve the stability of the emulsion.

[0034] (4) The present invention uses water as a dispersion medium to prepare the emulsion, which reduces the use of organic solvents, is environmentally friendly, and meets environmental protection requirements. The prepared calcium stearate emulsion has a stable emulsion form and contains active groups. When applied to rubber, it can be evenly dispersed in the rubber matrix and used as a lubricant, release agent and stabilizer in rubber processing to reduce the friction between rubber molecules, improve the fluidity and processing performance of rubber, improve the surface finish and demoulding efficiency of rubber products, and improve the physical properties and quality stability of rubber products. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0036] Example 1

[0037] A method for preparing a calcium stearate emulsion comprises the following steps:

[0038] (1) Ultrasonic dispersion of nano-silica in a 75%wt ethanol aqueous solution, after uniform dispersion, adding γ-methacryloxypropyltrimethoxysilane, the mass ratio of nano-silica, ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:3800:18, adjusting the pH to 4 with hydrochloric acid solution, stirring and mixing, reacting, the reaction temperature is 70°C, the reaction time is 8h, after the reaction is completed, filtering, washing with anhydrous ethanol and deionized water, and vacuum drying at 60°C for 12h to obtain modified silica;

[0039] (2) ultrasonically dispersing the modified silica into N,N-dimethylformamide, and after uniform dispersion, adding butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate, wherein the mass ratio of the modified silica, N,N-dimethylformamide, butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate is 9:750:5:100:35:12:7:1, stirring and mixing, reacting, the reaction temperature is 65°C, the reaction time is 8h, after the reaction is completed, cooling, filtering, washing with anhydrous ethanol, and drying at 60°C for 6h to obtain a silica-based composite emulsifier;

[0040] (3) Stearic acid is heated to a molten state at 70°C, calcium hydroxide is added and stirred and mixed at a speed of 350 r / min, a reaction occurs, and the reaction time is 1.5 h. After the reaction is completed, deionized water is added, the temperature is raised to 80°C, and a silica-based composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, defoaming agent polydimethylsiloxane, and dispersant sodium polyacrylate is 300:100:2100:95:0.5:1, the pH value is adjusted to 8, the mixture is stirred and mixed, the stirring time is 1 h, the stirring rate is 1800 r / min, and after mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0041] Example 2

[0042] A method for preparing a calcium stearate emulsion comprises the following steps:

[0043] (1) Ultrasonic dispersion of nano-silica in a 75%wt ethanol aqueous solution, after uniform dispersion, adding γ-methacryloxypropyltrimethoxysilane, the mass ratio of nano-silica, ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:4200:25, adjusting the pH to 4 with hydrochloric acid solution, stirring and mixing, reacting, the reaction temperature is 75°C, the reaction time is 6h, after the reaction is completed, filtering, washing with anhydrous ethanol and deionized water, and vacuum drying at 60°C for 12h to obtain modified silica;

[0044] (2) ultrasonically dispersing the modified silica into N,N-dimethylformamide, and after uniform dispersion, adding butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate, wherein the mass ratio of the modified silica, N,N-dimethylformamide, butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate is 12:850:6:100:40:15:8:1.5, stirring and mixing, reacting, the reaction temperature is 70°C, the reaction time is 7h, after the reaction is completed, cooling, filtering, washing with anhydrous ethanol, and drying at 60°C for 6h to obtain a silica-based composite emulsifier;

[0045] (3) Stearic acid is heated to a molten state at 75°C, calcium hydroxide is added and stirred and mixed at a speed of 400 r / min, a reaction occurs, and the reaction time is 2 h. After the reaction is completed, deionized water is added, the temperature is raised to 85°C, and a silica-based composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, defoaming agent polydimethylsiloxane, and dispersant sodium polyacrylate is 310:100:2200:100:0.6:1.5, the pH value is adjusted to 8, and the mixture is stirred and mixed for 1.5 h at a stirring and mixing speed of 2000 r / min. After mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0046] Example 3

[0047] A method for preparing a calcium stearate emulsion comprises the following steps:

[0048] (1) Ultrasonic dispersion of nano-silica in a 75%wt ethanol aqueous solution, after uniform dispersion, adding γ-methacryloxypropyltrimethoxysilane, the mass ratio of nano-silica, ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:4200:25, adjusting the pH to 4 with hydrochloric acid solution, stirring and mixing, reacting, the reaction temperature is 75°C, the reaction time is 6h, after the reaction is completed, filtering, washing with anhydrous ethanol and deionized water, and vacuum drying at 60°C for 12h to obtain modified silica;

[0049] (2) ultrasonically dispersing the modified silica into N,N-dimethylformamide, and after uniform dispersion, adding butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate, wherein the mass ratio of the modified silica, N,N-dimethylformamide, butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate is 15:850:7:100:45:18:9:1.8, stirring and mixing, reacting, the reaction temperature is 70°C, the reaction time is 7h, after the reaction is completed, cooling, filtering, washing with anhydrous ethanol, and drying at 60°C for 6h to obtain a silica-based composite emulsifier;

[0050] (3) Stearic acid is heated to a molten state at 75°C, calcium hydroxide is added and stirred and mixed at a speed of 400 r / min, a reaction occurs, and the reaction time is 2 h. After the reaction is completed, deionized water is added, the temperature is raised to 85°C, and a silica-based composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, defoaming agent polydimethylsiloxane, and dispersant sodium polyacrylate is 310:100:2200:112:0.6:1.5, the pH value is adjusted to 8, and the mixture is stirred and mixed for 1.5 h at a stirring and mixing speed of 2000 r / min. After mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0051] Example 4

[0052] A method for preparing a calcium stearate emulsion comprises the following steps:

[0053] (1) Ultrasonic dispersion of nano-silica in a 75%wt ethanol aqueous solution, after uniform dispersion, adding γ-methacryloxypropyltrimethoxysilane, the mass ratio of nano-silica, ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:4500:30, adjusting the pH to 4 with hydrochloric acid solution, stirring and mixing, reacting, the reaction temperature is 80°C, the reaction time is 8h, after the reaction is completed, filtering, washing with anhydrous ethanol and deionized water, and vacuum drying at 60°C for 12h to obtain modified silica;

[0054] (2) ultrasonically dispersing the modified silica into N,N-dimethylformamide, and after uniform dispersion, adding butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate, wherein the mass ratio of the modified silica, N,N-dimethylformamide, butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate is 16:950:8:100:48:20:10:2, stirring and mixing, reacting, the reaction temperature is 75°C, the reaction time is 6 hours, after the reaction is completed, cooling, filtering, washing with anhydrous ethanol, and drying at 60°C for 6 hours to obtain a silica-based composite emulsifier;

[0055] (3) Stearic acid is heated to a molten state at 80°C, calcium hydroxide is added and stirred and mixed at a speed of 450 r / min, a reaction occurs, and the reaction time is 3 hours. After the reaction is completed, deionized water is added, the temperature is raised to 90°C, and a silica-based composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, defoaming agent polydimethylsiloxane, and dispersant sodium polyacrylate is 320:100:2400:120:1:3, the pH value is adjusted to 8, the mixture is stirred and mixed, the stirring time is 2 hours, the stirring rate is 2400 r / min, and after mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0056] Comparative Example 1

[0057] A method for preparing a calcium stearate emulsion comprises the following steps:

[0058] (1) N,N-dimethylformamide, butylated acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate in a mass ratio of 850:7:100:45:18:9:1.8 were stirred and mixed to react at a temperature of 70° C. for 7 hours. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol, and dried at 60° C. for 6 hours to obtain a composite emulsifier;

[0059] (2) Stearic acid is heated to a molten state at 75° C., calcium hydroxide is added and stirred and mixed at a speed of 400 r / min, a reaction occurs, and the reaction time is 2 h. After the reaction is completed, deionized water is added, the temperature is raised to 85° C., and nano-silicon dioxide, a composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, nano-silicon dioxide, a composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate is 310:100:2200:8:104:0.6:1.5, the pH value is adjusted to 8, the mixture is stirred and mixed, the stirring time is 1.5 h, the stirring rate is 2000 r / min, and after mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0060] Comparative Example 2

[0061] A method for preparing a calcium stearate emulsion comprises the following steps:

[0062] (1) Ultrasonic dispersion of nano-silica in a 75%wt ethanol aqueous solution, after uniform dispersion, adding γ-methacryloxypropyltrimethoxysilane, the mass ratio of nano-silica, ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:4200:25, adjusting the pH to 4 with hydrochloric acid solution, stirring and mixing, reacting, the reaction temperature is 75°C, the reaction time is 6h, after the reaction is completed, filtering, washing with anhydrous ethanol and deionized water, and vacuum drying at 60°C for 12h to obtain modified silica;

[0063] (2) ultrasonically dispersing the modified silica into N,N-dimethylformamide, and after uniform dispersion, adding acrylic acid, 2-hydroxyethyl acrylate, maleic anhydride, polyethylene glycol and initiator ammonium persulfate, wherein the mass ratio of the modified silica, N,N-dimethylformamide, acrylic acid, 2-hydroxyethyl acrylate, maleic anhydride, polyethylene glycol and initiator ammonium persulfate is 15:850:100:45:18:9:1.8, stirring and mixing, reacting, the reaction temperature is 70°C, the reaction time is 7h, after the reaction is completed, cooling, filtering, washing with anhydrous ethanol, and drying at 60°C for 6h to obtain a silica-based composite emulsifier;

[0064] (3) Stearic acid is heated to a molten state at 75°C, calcium hydroxide is added and stirred and mixed at a speed of 400 r / min, a reaction occurs, and the reaction time is 2 hours. After the reaction is completed, deionized water is added, the temperature is raised to 85°C, and a silica-based composite emulsifier, β-cyclodextrin, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, β-cyclodextrin, defoaming agent polydimethylsiloxane, and dispersant sodium polyacrylate is 310:100:2200:4:108:0.6:1.5, the pH value is adjusted to 8, and the mixture is stirred and mixed for 1.5 hours at a speed of 2000 r / min. After mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0065] Comparative Example 3

[0066] A method for preparing a calcium stearate emulsion comprises the following steps:

[0067] (1) N,N-dimethylformamide, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator ammonium persulfate in a mass ratio of 850:100:45:18:9:1.8 were stirred and mixed to react at a temperature of 70° C. for 7 hours. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol, and dried at 60° C. for 6 hours to obtain a composite emulsifier;

[0068] (2) Stearic acid is heated to a molten state at 75°C, calcium hydroxide is added and stirred and mixed at a speed of 400 r / min, a reaction occurs, and the reaction time is 2 h. After the reaction is completed, deionized water is added, the temperature is raised to 85°C, and nano-silicon dioxide, β-cyclodextrin, a composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate are added, wherein the mass ratio of stearic acid, calcium hydroxide, deionized water, nano-silicon dioxide, β-cyclodextrin, a composite emulsifier, a defoaming agent polydimethylsiloxane, and a dispersant sodium polyacrylate is 310:100:2200:8:4:100:0.6:1.5, the pH value is adjusted to 8, the mixture is stirred and mixed, the stirring time is 1.5 h, the stirring rate is 2000 r / min, and after mixing evenly, the mixture is slowly cooled to obtain a calcium stearate emulsion.

[0069] The nano-silicon dioxide used in the examples and comparative examples of the present invention was purchased from Jiangsu Lianyungang Pengrui Chemical Co., Ltd., with a particle size of 15 nm; the polyethylene glycol was polyethylene glycol 6000, purchased from Sinopharm Chemical Reagent Co., Ltd.; other raw materials and reagents not specified were commercially available.

[0070] The calcium stearate emulsions prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to relevant performance tests, as follows:

[0071] (1) Dispersibility test: 1 mL of the emulsion was diluted with deionized water to a transmittance of 80%. After ultrasonic dispersion for 5 min, the test was performed. The particle size distribution of the emulsion was tested using a BT-9300Z laser particle size distribution analyzer, where the refractive index of the calcium stearate particles was 1.45, the refractive index of deionized water was 1.33, the absorbance was 0.01, the test range was 0.01-3500 μm, the circulating pump speed was 2000-2500 rpm, the measurement was repeated 3 times, and the average particle size and distribution were calculated;

[0072] (2) Stability test

[0073] 1) Centrifugal stability: Place the calcium stearate emulsion in a centrifuge, set the speed to 4000r / min, and centrifuge for 15min. Determine the stability of the emulsion based on the stratification effect. The worse the stratification effect, the better the emulsion stability.

[0074] Storage stability: Store in a constant temperature box at 25°C, relative humidity 60%, away from light for 30 days, and calculate the delamination rate and precipitation amount. The calculation method of the delamination rate is delamination rate (%) = (H 1 / H 0 )×100%, height of supernatant (H 1 ) and total height (H 0 ), the amount of sediment is the mass of the sediment at the bottom of the bottle after pouring the emulsion, which accounts for the mass of the original emulsion;

[0075] (3) Thermal stability test: The samples were freeze-dried at -50°C, ground, and 10 mg of the samples were weighed for thermogravimetric analysis. The test was conducted in a nitrogen atmosphere at a heating rate of 10°C / min. The decomposition temperature (T d );

[0076] The above test results are shown in Table 1:

[0077] Table 1

[0078]

[0079]

[0080] According to the test results of Table 1, it can be seen that the synergistic effect of modified silica and butylated acid monoesterified-β-cyclodextrin in Examples 1-4 of the present invention effectively inhibits agglomeration, and the corresponding calcium stearate emulsion has excellent performance, excellent dispersibility, and good stability. In Comparative Example 1, nano silicon dioxide was not modified and directly added to the emulsion, and the interface compatibility was poor, and agglomeration was easy to occur, resulting in a decrease in the overall stability of the emulsion and a deterioration in comprehensive performance. In Comparative Example 2, β-cyclodextrin was not modified, the inclusion capacity of β-cyclodextrin was reduced, the thermal stability of the emulsion was reduced, and the dispersibility was greatly reduced. In Comparative Example 3, the emulsification effect was poor, nano silicon dioxide was prone to agglomeration, and β-cyclodextrin was not modified, and the overall performance was greatly reduced, the dispersibility was poor, and the stability and heat resistance were greatly reduced.

[0081] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing a calcium stearate emulsion, characterized in that: The steps include: Step 1, ultrasonically disperse nano-silica into an ethanol solution, and after uniform dispersion, add γ-methacryloxypropyltrimethoxysilane, adjust the pH to 4, stir and mix, react, and after the reaction is completed, filter, wash, and vacuum dry at 60° C. for 12 hours to obtain modified silica; Step 2, ultrasonically dispersing the modified silicon dioxide in N,N-dimethylformamide, after uniform dispersion, adding butenedioic acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator, stirring and mixing, reacting, cooling, filtering, washing and drying at 60° C. for 6 hours after the reaction is completed, to obtain a silicon dioxide-based composite emulsifier; Step 3: Heat stearic acid to a molten state, add calcium hydroxide, stir and mix, react, add deionized water after the reaction is completed, heat up, add a silica-based composite emulsifier, a defoamer, and a dispersant, adjust the pH value to 8, stir and mix, mix evenly, and slowly cool to obtain a calcium stearate emulsion.

2. The method for preparing a calcium stearate emulsion according to claim 1, wherein: In the step 2, the mass ratio of modified silica, N,N-dimethylformamide, butylated acid monoesterified-β-cyclodextrin, acrylic acid, 2-hydroxyethyl acrylic acid, maleic anhydride, polyethylene glycol and initiator is (9-16):(750-950):(5-8):100:(35-48):(12-20):(7-10):(1-2).

3. The method for preparing a calcium stearate emulsion according to claim 1, wherein: The reaction temperature in step 2 is 65-75° C., and the reaction time is 6-8 h.

4. A method for preparing a calcium stearate emulsion according to claim 1, characterized in that: In the step 2, the initiator is selected from any one of ammonium persulfate, potassium persulfate and benzoyl peroxide.

5. A method for preparing a calcium stearate emulsion according to claim 1, characterized in that: In the step three, the mass ratio of stearic acid, calcium hydroxide, deionized water, silica-based composite emulsifier, defoamer and dispersant is (300-320):100:(2100-2400):(95-120):(0.5-1):(1-3).

6. A method for preparing a calcium stearate emulsion according to claim 1, characterized in that: The reaction time in step 3 is 1.5-3h, and the stirring speed during the reaction is 350-450r / min.

7. A method for preparing a calcium stearate emulsion according to claim 1, characterized in that: The temperature after heating in step 3 is 80-90° C., the stirring and mixing time is 1-2 hours, and the stirring and mixing rate is 1800-2400 r / min.

8. A method for preparing a calcium stearate emulsion according to claim 1, characterized in that: The defoaming agent in step 3 is a water-soluble silane defoaming agent; The dispersant in step three includes any one of alkylphenol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether and sodium polyacrylate.

9. A calcium stearate emulsion prepared by the preparation method of the calcium stearate emulsion according to any one of claims 1 to 8.

10. Use of the calcium stearate emulsion according to claim 9 in rubber.

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