A hydrophobic fumed silica water-dispersible sol and a method for its preparation

Abstract

The application discloses a water-dispersible sol of hydrophobic fumed silica and a preparation method thereof. The water-dispersible sol of hydrophobic fumed silica comprises the following raw materials in mass proportions: hydrophobic fumed silica: 25-70; oily substance: 0-300; co-emulsifier: 0-50; and liquid hydrophilic surface active substance: 100. The hydrophobic fumed silica content of the application is very high, and the mass fraction can be up to 41.18%, which is an ideal source of hydrophobic fumed silica. The optional range of the oily substance and the surface active substance is very wide, and the application can be flexibly regulated according to different application requirements. In addition, the application is easy to disperse in water and has good dispersion stability, and is suitable for being added into a coating, a pigment, a water-based film material, a release agent, an emulsion polymer and other systems as a source of hydrophobic fumed silica. Furthermore, the application does not contain a solvent, and when added into other systems, the solvent is not introduced, and the application has a wide application field and good application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aqueous materials, and particularly relates to a water-dispersible sol of hydrophobic fumed silica and a preparation method thereof. BACKGROUND

[0002] The hydrophobic fumed silica is a kind of nanometer material with hydrophobic and lipophilic properties, which is prepared by modifying hydrophilic fumed silica, i.e. fumed silica, with active silane or silazane. It is a kind of hydrophobic and lipophilic amorphous nanometer powder material, which has good compatibility with organic substances, is easy to disperse in organic substances, and provides multiple functions such as thickening, thixotropy, anti-settling, ultraviolet absorption, infrared reflection, extinction, improvement of weather resistance and anti-aging, and enhancement of stability, etc. It is widely used in the fields of coatings, film materials, plastics, resins, rubber, pigments, sealants, adhesives, medicines, cosmetics, optical materials, catalysts, etc.

[0003] In recent years, due to the increasing environmental protection requirements, the application of oily and toxic and harmful solvents is more and more strictly limited, and materials such as coatings, release agents, pigments, etc. gradually begin to be water-based. For the hydrophobic fumed silica, it is difficult to disperse in water. The surface of the hydrophobic fumed silica is distributed with dense alkyl groups, which has strong hydrophobicity and is difficult to enter the water phase. Moreover, the particle size of the hydrophobic fumed silica is extremely small, and the bulk density is extremely low. If it is stirred with water, it is not only difficult to be compatible with water, but also produces serious dust, causing health damage, environmental pollution, material waste, etc.

[0004] Starting from the lipophilic characteristics of the hydrophobic fumed silica, it is easy to think that the compatibility of the hydrophobic fumed silica with water can be improved by adding a surfactant to the water. However, the hydrophobic fumed silica is a kind of microparticle with amorphous and certain rigidity, and its microstructure is complex with a huge specific surface area. When it enters the water phase, it often wraps a lot of air, which produces a large number of water-air interfaces, consumes a high proportion of surfactants, and causes the hydrophobic fumed silica microparticles to aggregate into groups. The actual dispersed particle size is much larger than the size of the hydrophobic fumed silica itself, and the thixotropy and thickening properties cannot be fully utilized. Moreover, the air bubbles wrapped will make the hydrophobic fumed silica float to the surface of the system and even return to the gas phase, which is not conducive to the dispersion stability of the hydrophobic fumed silica. Therefore, strong dispersion methods such as high-speed shearing homogenization and vacuum homogenization are usually required to disperse the hydrophobic fumed silica well in water. However, this method consumes a lot of energy, and often needs to mix the hydrophobic fumed silica with alcohol or oily solvent to expel the air between the microparticles, so as to promote the dispersion of the hydrophobic fumed silica in water by emulsifying the solvent and the hydrophobic fumed silica together. Therefore, it cannot completely get rid of the solvent.

[0005] Therefore, there is an urgent need to provide a new way of introducing hydrophobic fumed silica which is convenient, safe, environmentally friendly and low energy consumption. SUMMARY

[0006] In view of the above-mentioned shortcomings or deficiencies of the prior art, the technical problem to be solved by the present application is to provide a water-dispersible sol of hydrophobic fumed silica and a preparation method thereof.

[0007] To solve the above technical problems, the present application realizes the following technical solutions:

[0008] The present application provides a water-dispersible sol of hydrophobic fumed silica, which comprises the following raw materials in the following mass proportions: hydrophobic fumed silica: 25-70; oily substance: 0-300; co-emulsifier: 0-50; liquid hydrophilic surfactant: 100.

[0009] Optionally, the water-dispersible sol of hydrophobic fumed silica, wherein the oily substance comprises one or a combination of the following substances: polyol fatty acid ester with a melting point ≤ 50℃, non-aqueous and non-aqueous reactive under neutral acid-base conditions, and a hydroxyl number ≤ 1; non-aqueous and non-aqueous reactive coating catalyst drier; wax with a melting point ≤ 50℃; surfactant with an HLB value ≤ 10; non-aqueous and non-aqueous reactive polymer monomer with a melting point ≤ 50℃; polyalkylsiloxane with a viscosity ≤ 100 cst at 25℃; polyolefin with a viscosity ≤ 300 cst at 100℃, which is liquid at room temperature; epoxy resin with a viscosity ≤ 15000 mPa·s at 25℃; fatty acid amide opening agent with a melting point ≤ 80℃; or non-aqueous and non-aqueous reactive organic compound with a melting point ≤ 50℃, and an oil-wet group with a carbon atom number ≥ 4.

[0010] Optionally, the water-dispersible sol of hydrophobic fumed silica, wherein the co-emulsifier comprises one or a combination of the following substances: primary alcohol with a melting point ≤ 70℃ and a carbon atom number of 8-24; primary amine with a melting point ≤ 70℃ and a carbon atom number of 8-18; triethanolamine; triisopropanolamine; tetrahydroxyethyl ethylenediamine; penta-hydroxyethyl diethylene triamine; triethanolamine borate; melamine substituted with 1-6 hydroxyethyl groups; tri-tall oil; or tri-tall oil borate.

[0011] Optionally, the water-dispersible sol of hydrophobic fumed silica, wherein the liquid hydrophilic surfactant comprises one or a combination of the following substances: aqueous solution or aqueous suspension of surfactant with a mass fraction ≥ 20%; solution or suspension of a mixture of solid surfactant and liquid surfactant; liquid surfactant; or mixture containing non-surfactant but having surface activity and being liquid after mixing.

[0012] Optionally, the hydrophobic fumed silica water dispersible sol, wherein the liquid hydrophilic surfactant has an HLB value of 10 or more.

[0013] The present application also provides a method for preparing a hydrophobic fumed silica water dispersible sol, comprising the following steps:

[0014] The following raw materials are weighed separately: 25-70 parts by mass of hydrophobic fumed silica, 0-300 parts by mass of oily substance, 0-50 parts by mass of co-emulsifier, and 100 parts by mass of liquid hydrophilic surfactant;

[0015] Mixing the raw materials: the weighed raw materials are put into a container, and the oily substance is put in first, followed by the co-emulsifier and the liquid hydrophilic surfactant;

[0016] After each addition, stir until uniform before adding the next ingredient;

[0017] After all the ingredients have been added, stir until fully mixed to obtain the hydrophobic fumed silica water dispersible sol.

[0018] Optionally, the method for preparing a hydrophobic fumed silica water dispersible sol, wherein when the hydrophobic fumed silica is composed of two or more components, they are pre-mixed and stirred until uniform before being added; when the oily substance, co-emulsifier, or liquid hydrophilic surfactant is composed of two or more components, they can be pre-mixed and stirred until uniform before being added, or they can be added directly without pre-mixing and without any order; the materials can be added in batches to ensure uniform stirring, and the hydrophobic fumed silica can be added alternately with the remaining raw materials to avoid the formation of hard lumps due to excessive local concentration in the container, which makes it difficult to stir and disperse.

[0019] Optionally, the method for preparing a hydrophobic fumed silica water dispersible sol, wherein when the oily substance contains a solid at room temperature, or when the environmental temperature is too low to cause some components in the oily substance, co-emulsifier, or liquid hydrophilic surfactant to have too high viscosity or to dissolve slowly, making it difficult to stir, water bath heating at a temperature not higher than 70°C is performed during stirring, and the water bath heating continues until all the ingredients have been added and fully mixed; for oily substances that are unstable in air, such as unsaturated polymer monomers and drying oils, CO2 protection or nitrogen protection can be used during stirring.

[0020] Optionally, the method for preparing a hydrophobic fumed silica water dispersible sol, wherein after the sol has been stirred until fully mixed, it can be subjected to vacuum defoaming treatment as needed, and for sols containing water, the vacuum defoaming treatment can be performed after cooling to room temperature.

[0021] Optionally, the production method described above, wherein, according to different raw materials or different proportions, two or more than two kinds of the hydrophobic fumed silica water-dispersible sols are mixed in any proportion, and the mixture is still the hydrophobic fumed silica water-dispersible sol after mixing; the mixing includes direct mixing or mixing after diluting the hydrophobic fumed silica water-dispersible sol into a hydrosol.

[0022] Specifically, the production method described above, wherein, the compatibility of each component refers to that no physical or chemical reaction occurs between each component which is not conducive to the stability of the mixture system, and macroscopically, after mixing two or more than two kinds of the hydrophobic fumed silica water-dispersible sols in any proportion, a homogeneous mixture can still be formed without deterioration such as caking, solidification, segregation, and dramatic increase in viscosity, and after dilution with water, a hydrosol can still be uniformly dispersed and remain uniform and stable for more than 60 days without segregation.

[0023] Optionally, the production method described above, wherein, the sufficient mixing refers to that a small amount of raw materials is mixed to obtain a mixture, the mixture is placed on a glass plate, and the mixture is scraped with a scraper to form a transparent liquid film with uniform thickness, and the liquid film is observed to be uniform in color without particles or dark spots.

[0024] Compared with the prior art, the present application has the following technical effects:

[0025] (1) The hydrophobic fumed silica water-dispersible sol of the present application can be dispersed in water by simple low-speed stirring or manual stirring to form a semi-transparent blue light hydrosol or white emulsion, which can be stable for more than 60 days without precipitation, floating, layering, flocculation, and other phenomena without additional addition of any stabilizer.

[0026] (2) The hydrophobic fumed silica water-dispersible sol of the present application has a high content of hydrophobic fumed silica, and the mass fraction can be as high as 41.18%, which is an ideal source of hydrophobic fumed silica. The range of optional oily substances and surface active substances is extremely wide, which can be flexibly adjusted according to different application requirements. The hydrophobic fumed silica water-dispersible sol can be uniformly dispersed in water to obtain a stable hydrosol by low-speed stirring without high-speed shearing homogenization, vacuum homogenization, and other processes, which is suitable for being added into coating, pigment, water-based film material, release agent, emulsion polymer, and other systems as a source of hydrophobic fumed silica. In addition, the hydrophobic fumed silica water-dispersible sol of the present application does not contain solvent, and therefore does not introduce solvent when added into other systems. Therefore, the present application provides a new way of introducing hydrophobic fumed silica which is convenient, safe, environmentally friendly, and low in energy consumption, and has a wide application field and good application prospect. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0028] The raw materials used in the following examples are all commercially available industrial-grade chemical raw materials, unless otherwise specified.

[0029] Examples 1-19

[0030] Examples 1-19 do not contain the oily substance, and the specific embodiment is as follows: the co-emulsifier, the hydrophilic surface active substance in liquid state and the hydrophobic fumed silica are added into a container, when there are multiple components of the co-emulsifier or the hydrophilic surface active substance in liquid state, the components are added without sequence and without pre-stirring, and the components and the ratio are shown in Table 1 below, wherein the hydrophilic surface active substance in liquid state in Examples 1-9 is in liquid state or aqueous solution, the hydrophilic surface active substance in liquid state in Examples 10-16 is in suspension, and the hydrophilic surface active substance in liquid state in Examples 17-19 is a mixture containing non-surface active substance but having surface activity and being in liquid state after mixing, then the mixture is fully stirred, cooled to room temperature, and vacuum degassed to obtain the water-dispersible sol of the hydrophobic fumed silica.

[0031] Table 1 Raw material components and ratio table of Examples 1-19

[0032]

[0033] Continued Table 1 Raw material components and ratio table of Examples 1-19

[0034]

[0035] Continued Table 1 Raw material components and ratio table of Examples 1-19

[0036]

[0037] Continued Table 1 Raw material components and ratio table of Examples 1-19

[0038]

[0039] Continued Table 1 Raw material components and ratio table of Examples 1-19

[0040]

[0041] Continued Table 1 Raw material components and ratio table of Examples 1-19

[0042]

[0043] Note: In Example 18, triethanolamine borate was used in combination with titanate coupling agent 201, i.e. isopropoxy tris(dioctyl pyrophosphato) titanate, to form a "mixture with surface activity" rather than as a co-emulsifier, on the same principle as the combination of bis(dioctyl pyrophosphato) ethylene titanate with triethanolamine in titanate coupling agent 311W.

[0044] The appearance and properties of Examples 1-19 are shown in Table 2 below:

[0045] Table 2 Detailed table of appearance and properties of Examples 1-19

[0046]

[0047] Examples 20-25

[0048] Examples 20-25 were obtained by mixing two or more of the hydrophobic fumed silicas described directly in water-dispersible sols, the components and proportions being shown in Table 3 below, and the mixture was stirred thoroughly, degassed under vacuum after cooling to room temperature, to obtain Examples 20-25. The specific appearance and properties are shown in Table 4.

[0049] Comparative Example 1

[0050] Comparative Example 1 was obtained by mixing two of the hydrophobic fumed silicas described, the components and proportions being shown in Table 3 below, but the components were not compatible. The mixture was stirred thoroughly, degassed under vacuum after cooling to room temperature, to obtain Comparative Example 1. The specific appearance and properties are shown in Table 4.

[0051] Table 3 Components and proportions of Examples 20-25 and Comparative Example 1

[0052]

[0053] Table 4 Detailed table of appearance and properties of Examples 20-25 and Comparative Example 1

[0054]

[0055]

[0056] Comparative Example 1 is a case where the components of the two water-dispersible sols of the hydrophobic fumed silica are incompatible, and when mixed, the mixture is lumpy and cannot be stirred uniformly, and after dilution, the mixture precipitates and cannot be dispersed. The reason for the incompatibility of the components is that the anionic surfactant reacts with the cationic surfactant to precipitate insoluble crystals. The charge attraction between the cation and the cation is stronger than the adsorption of the hydrophobic fumed silica to the hydrophobic end of the surfactant, so that a large amount of the anionic surfactant and the cationic surfactant originally adsorbed on the surface of the hydrophobic fumed silica are stripped off, and cannot play a role in dispersing the hydrophobic fumed silica. The remaining anionic surfactant and cationic surfactant that have not been stripped off are also attracted to each other by the charge attraction, causing the hydrophobic fumed silica particles to come close to each other and agglomerate, and thus cannot be dispersed in water.

[0057] Examples 26 to 29

[0058] Examples 26 to 29 are cases where two or more water-dispersible sols of the hydrophobic fumed silica are diluted with 4.5 times the mass of water to form water sols, and then mixed and stirred uniformly to obtain a mixed dilution. The components and ratios are shown in Table 5 below, and the appearance and properties of the dilutions are shown in Table 6 below.

[0059] Comparative Examples 2 to 4

[0060] Comparative Examples 2 to 4 are cases where the components of two or more water-dispersible sols of the hydrophobic fumed silica are incompatible. The components and ratios are shown in Table 5 below, and the appearance and properties of the dilutions are shown in Table 6 below.

[0061] Table 5 Components and Ratios of Examples 26 to 29 and Comparative Examples 2 to 4

[0062]

[0063]

[0064] Note: In Comparative Example 4, isomeric decanol polyoxyethylene ether 1007 does not need to be diluted with water in advance.

[0065] Table 6 Appearance and Property Details of Examples 26 to 29 and Comparative Examples 2 to 4

[0066]

[0067] The incompatibility of the components of the two water-dispersible sols of the hydrophobic fumed silica in Comparative Examples 2 to 4 is the same as in Comparative Example 1, and will not be described again. The insoluble crystals precipitated by the reaction of the anionic surfactant with the cationic surfactant are the source of the pearlescence of the dilution.

[0068] The systems of Examples 26-29 also contain anionic surfactant and cationic surfactant, but both are first mixed with nonionic surfactant isomeric decanol polyoxyethylene ether 1007 uniformly and pre-diluted before contact. Under the joint action of nonionic surfactant and water, the anionic surfactant and cationic surfactant react to precipitate extremely small liquid crystals instead of insoluble crystals, and still have good dispersion effect on hydrophobic fumed silica, i.e. the two are compatible. This process requires the participation of water, so Comparative Example 1, which contains only nonionic surfactant and no water, does not have this phenomenon; in addition, this process also requires the anionic surfactant and cationic surfactant to be first mixed with nonionic surfactant uniformly before contact, Examples 28, Comparative Examples 3-4 have the same ratio of surface active substances and content of hydrophobic fumed silica, but the addition of nonionic surfactant in Comparative Examples 3-4 cannot achieve the uniform mixing of anionic surfactant and cationic surfactant with nonionic surfactant before contact, and cannot form a stable diluent.

[0069] In addition, the nonionic surfactant has a plasticizing effect on the adsorption layer of the above-mentioned liquid crystals formed on the surface of the hydrophobic fumed silica, and inhibits the phenomenon of charge attraction pulling the hydrophobic fumed silica particles close to each other and agglomerating, which macroscopically manifests as a decrease in viscosity and an increase in stability. In Examples 28, 27, 26, and 29, the content of nonionic surfactant decreases in turn, the viscosity of the diluent increases in turn, and the stability decreases.

[0070] Examples 30-41

[0071] Examples 30-41 contain oily substances, and the appearance and properties are shown in Table 7 below.

[0072] Example 30

[0073] 70 g of hydrophobic fumed silica, 300 g of linseed oil, 50 g of triethanolamine borate, 75 g of cocamidopropyl hydroxysultaine (35%), and 25 g of isomeric tridecanol polyoxyethylene ether carboxylic acid sodium IAEC-1307Na (98%) were weighed out respectively.

[0074] 30 g of hydrophobic fumed silica, 300 g of linseed oil, and 50 g of triethanolamine borate were added to a container and stirred until they were roughly uniform. Then 20 g of hydrophobic fumed silica and 50 g of cocamidopropyl hydroxysultaine (35%) were added and stirred until they were roughly uniform. Then 20 g of hydrophobic fumed silica, 25 g of cocamidopropyl hydroxysultaine (35%), and 25 g of isomeric tridecanol polyoxyethylene ether carboxylic acid sodium IAEC-1307Na (98%) were added and stirred until they were thoroughly uniform. After cooling to room temperature, the mixture was vacuum degassed.

[0075] Example 31

[0076] In Example 30, 300 g of linseed oil is replaced by 300 g of PEG 400 bisoleate (HLB value 7-8), and the rest of the formulation and the operation steps remain unchanged.

[0077] Example 32

[0078] 70 g of hydrophobic fumed silica, 100 g of cobalt isooctoate (cobalt content 12%), 50 g of triethanolamine borate, 75 g of cocamidopropyl hydroxysultaine (35%), and 25 g of octadecylamine polyoxyethylene ether AC1810 (99%) are weighed out respectively.

[0079] Into a container, 30 g of hydrophobic fumed silica, 100 g of cobalt isooctoate (cobalt content 12%), and 50 g of triethanolamine borate are added and stirred until roughly uniform. Then, 25 g of hydrophobic fumed silica and 50 g of cocamidopropyl hydroxysultaine (35%) are added and stirred until roughly uniform. Then, 15 g of hydrophobic fumed silica, 25 g of cocamidopropyl hydroxysultaine (35%), and 25 g of octadecylamine polyoxyethylene ether AC1810 (99%) are added and stirred until uniform. After cooling to room temperature, vacuum defoaming is performed.

[0080] Example 33

[0081] 50 g of hydrophobic fumed silica, 100 g of semi-refined paraffin wax No. 45, 20 g of triethanolamine, 50 g of cocamidopropyl hydroxysultaine (35%), 25 g of cocamidopropyl betaine (97%), and 25 g of isomeric tridecanol polyoxyethylene ether carboxylic acid sodium IAEC-1307Na (98%) are weighed out respectively.

[0082] Into a container, 100 g of semi-refined paraffin wax No. 45 is added and heated in a 50°C water bath until melted. Then, 20 g of triethanolamine and 20 g of hydrophobic fumed silica are added and stirred until roughly uniform. Then, 20 g of hydrophobic fumed silica and 50 g of cocamidopropyl hydroxysultaine (35%) are added and stirred until roughly uniform. Then, 5 g of hydrophobic fumed silica, 25 g of cocamidopropyl betaine (97%) are added and stirred until roughly uniform. Then, 5 g of hydrophobic fumed silica and 25 g of isomeric tridecanol polyoxyethylene ether carboxylic acid sodium IAEC-1307Na (98%) are added and stirred until uniform. After removing the water bath heating, vacuum defoaming is performed after cooling to room temperature.

[0083] Example 34

[0084] 70 g of hydrophobic fumed silica, 150 g of lauryl methacrylate, 10 g of lauryl alcohol, 70 g of cocamidopropyl hydroxysultaine (35%), and 30 g of sodium dodecylbenzenesulfonate are weighed out respectively.

[0085] Into a vessel, add 45 g hydrophobic fumed silica, 150 g lauryl methacrylate, 10 g lauryl alcohol, stir until approximately uniform, add 15 g hydrophobic fumed silica, 50 g cocamidopropyl hydroxysultaine (35%), stir until approximately uniform, add 10 g hydrophobic fumed silica, 20 g cocamidopropyl betaine (97%), 30 g sodium dodecylbenzenesulfonate, stir until uniform, vacuum degas after cooling to room temperature.

[0086] Example 35

[0087] Into a vessel, add 50 g hydrophobic fumed silica, 100 g dimethicone (100 cst), 10 g tetrahydroxyethyl ethylenediamine, stir until approximately uniform, add 50 g isomeric tridecyl alcohol polyoxethylene ether 1307 (99%), 25 g cocamidopropyl betaine (97%), 25 g isomeric tridecyl alcohol polyoxethylene ether carboxylate sodium IAEC-1307 Na (98%), stir until uniform, vacuum degas after cooling to room temperature.

[0088] Into a vessel, add 20 g hydrophobic fumed silica, 100 g dimethicone (100 cst), 10 g tetrahydroxyethyl ethylenediamine, stir until approximately uniform, add 20 g hydrophobic fumed silica, 50 g isomeric tridecyl alcohol polyoxethylene ether 1307 (99%), stir until approximately uniform, add 10 g hydrophobic fumed silica, 25 g cocamidopropyl betaine (97%), 25 g isomeric tridecyl alcohol polyoxethylene ether carboxylate sodium IAEC-1307 Na (98%), stir until uniform, vacuum degas after cooling to room temperature.

[0089] Example 36

[0090] Into a vessel, add 40 g hydrophobic fumed silica, 70 g polyisobutylene PB950 (230 cst), 20 g isomeric dodecanol, 50 g isomeric tridecyl alcohol polyoxethylene ether 1307 (99%), 25 g cocamidopropyl betaine (97%), 25 g isomeric tridecyl alcohol polyoxethylene ether carboxylate sodium IAEC-1307 Na (98%), stir until uniform, vacuum degas after cooling to room temperature.

[0091] Into a vessel, add 70 g polyisobutylene PB950 (230 cst), turn on 50 °C water bath heating, after the viscosity of the polyisobutylene is reduced, add 25 g hydrophobic fumed silica, 20 g isomeric dodecanol, 50 g isomeric tridecyl alcohol polyoxethylene ether 1307 (99%), stir until approximately uniform, add 15 g hydrophobic fumed silica, 25 g cocamidopropyl betaine (97%), 25 g isomeric tridecyl alcohol polyoxethylene ether carboxylate sodium IAEC-1307 Na (98%), stir until uniform, remove the water bath heating, vacuum degas after cooling to room temperature.

[0092] Example 37

[0093] Replace 70 g polyisobutylene PB950 (230 cst) in Example 36 with 70 g epoxy resin E51, and the rest of the formulation remains unchanged, and the operation steps remain unchanged.

[0094] Example 38

[0095] Take 45 g hydrophobic fumed silica, 150 g epoxy vinyl ester resin 901, 10 g isooctanol, 70 g cocamidopropyl hydroxysultaine (35%), and 30 g sodium dodecylbenzenesulfonate, respectively.

[0096] Under nitrogen protection, add 150 g epoxy vinyl ester resin 901 to the container, turn on the 50°C water bath heating, and after the viscosity of the epoxy vinyl ester resin decreases, add 20 g hydrophobic fumed silica, 10 g isooctanol, and stir until roughly uniform, then add 15 g hydrophobic fumed silica, 50 g cocamidopropyl hydroxysultaine (35%), and stir until roughly uniform, then add 10 g hydrophobic fumed silica, 20 g cocamidopropyl betaine (97%), and 30 g sodium dodecylbenzenesulfonate, and after stirring thoroughly, remove the water bath heating, and after cooling to room temperature, vacuum degassing.

[0097] Example 39

[0098] Take 40 g hydrophobic fumed silica, 100 g oleamide, 20 g tri-dan oil, 70 g cocamidopropyl hydroxysultaine (35%), and 30 g sodium isomeric tridecyl alcohol polyoxyethylene ether carboxylate IAEC-1307Na (98%), respectively.

[0099] Add 100 g oleamide to the container, turn on the 50°C water bath heating, and after the oleamide softens, add 25 g hydrophobic fumed silica, 20 g tri-dan oil, and 50 g cocamidopropyl hydroxysultaine (35%), and stir until roughly uniform, then add 10 g hydrophobic fumed silica, 20 g cocamidopropyl hydroxysultaine (35%), and stir until roughly uniform, then add 5 g hydrophobic fumed silica, and 30 g sodium isomeric tridecyl alcohol polyoxyethylene ether carboxylate IAEC-1307Na (98%), and after stirring thoroughly, remove the water bath heating, and after cooling to room temperature, vacuum degassing.

[0100] Example 40

[0101] Replace 100 g oleamide in Example 39 with 100 g hydroxyethyl ethylene bis-stearamide, and the rest of the formulation remains unchanged, and the operation steps remain unchanged.

[0102] Example 41

[0103] Take 50 g hydrophobic fumed silica, 100 g polyhydroxy stearic acid, 50 g triethanolamine borate, 50 g cocamidopropyl hydroxysultaine (35%), 25 g cocamidopropyl betaine (97%), 25 g sodium isomeric tridecyl alcohol polyoxyethylene ether carboxylate IAEC-1307Na (98%) respectively.

[0104] Into the container, add 35 g hydrophobic fumed silica, 100 g polyhydroxy stearic acid, 50 g triethanolamine borate, 50 g cocamidopropyl hydroxysultaine (35%), stir until roughly uniform, then add 15 g hydrophobic fumed silica, 25 g cocamidopropyl betaine (97%), 25 g sodium isomeric tridecyl alcohol polyoxyethylene ether carboxylate IAEC-1307Na (98%), stir well, and vacuum defoam after cooling to room temperature.

[0105] Table 7 Detailed table of appearance and properties of Examples 30-41 The water-dispersible sol of hydrophobic fumed silica prepared in the present application is a raw material for introducing hydrophobic fumed silica into systems such as coatings, pigments, water-based film materials, release agents, emulsion polymers, etc., which will be compounded with various other components in different application fields, which are not within the scope of the present application, so in the present application, only the dispersion of the water-dispersible sol of hydrophobic fumed silica in pure water is investigated, i.e. after dilution with 9 times the mass of water and stirring, the stability time is studied. In fact, in the above-mentioned application fields, additional dispersing aids are usually added to improve the dispersion stability, so the water-dispersible sol of hydrophobic fumed silica should have better dispersion stability in actual application.

[0106] In summary, the water-dispersible sol of the present application has a very high content of hydrophobic fumed silica, with a mass fraction of up to 41.18%, which is an ideal source of hydrophobic fumed silica, and the range of optional oily and surfactant materials is extremely wide, which can be flexibly adjusted according to different application requirements. In addition, the water-dispersible sol is easy to disperse in water and has good dispersion stability, and is suitable for being added as a source of hydrophobic fumed silica into systems such as coatings, pigments, water-based film materials, release agents, emulsion polymers, etc. Moreover, the water-dispersible sol does not contain solvent, so when added to other systems, it will not introduce solvent, thus providing a new way of introducing hydrophobic fumed silica that is convenient, safe and environmentally friendly, and has a wide application field and good application prospect.

[0107] The main principle of the water-dispersible sol of hydrophobic fumed silica of the present application lies in the strong adsorption of the lipophilic end of the surface active substance by the hydrophobic fumed silica, which makes it easy to disperse in a concentrated surface active substance system, usually a coating, pigment, water-based film material, release agent, emulsion polymer, etc. system will not add so much surfactant, because the excess surfactant has an adverse effect on the performance of the material, and is not economical, but considering that the amount of hydrophobic fumed silica added in these systems is usually small, the present application has prepared a water-dispersible sol with high content of hydrophobic fumed silica and surface active substance, on the one hand, the high content of surface active substance makes the content of hydrophobic fumed silica reach a high level, and the sol still has good stability and water dispersibility, on the other hand, the high content of hydrophobic fumed silica makes it only need to add a small amount of the sol to the coating, pigment, water-based film material, release agent, emulsion polymer, etc. system to achieve the required amount of hydrophobic fumed silica, reducing the amount of surface active substance introduced into the system, and the surface active substance used can be adjusted as needed to minimize the impact on the system. Overall, by adding hydrophobic fumed silica to the system using the water-dispersible sol of the present application, the amount of surface active agent introduced into the system is much less than that required when hydrophobic fumed silica is directly dispersed into the system, and the impact is also smaller.

[0108] In the water-dispersible sol of hydrophobic fumed silica of the present application, the strong adsorption of the lipophilic end of the surface active substance by the hydrophobic fumed silica not only improves the dispersibility and stability of the hydrophobic fumed silica, but also has an effect on the surface active substance itself.

[0109] On the one hand, such strong adsorption forces different surface active substances to form a compact and stable arrangement with the lipophilic end pointing to the hydrophobic fumed silica and the hydrophilic end pointing to the outside, forming a hydrophilic micelle with the hydrophobic fumed silica particles as the core and the hydrophilic end on the outside, reducing the requirements for the properties of the surface active substance itself, which is suitable for surface active agents with HLB values within 10-40 and their combinations, which is quite different from the conventional application of surface active agents. Generally, emulsifying an oily substance only applies to a very narrow range of surface active agents with HLB values around the matching value, for example, the HLB value range of surface active agents for emulsifying industrial soybean oil is generally 6.5-7.2.

[0110] On the other hand, strong adsorption also enables some usually infeasible surfactant application methods, for example, sodium dodecyl sulfate (solid), solubility at room temperature is about 15%, there is no stable aqueous solution with a mass fraction of 60%, at this concentration, the undissolved sodium dodecyl sulfate solid particles form a suspension, which cannot fully play a role, and the strong adsorption of hydrophobic fumed silica to the hydrophobic end of sodium dodecyl sulfate, i.e. dodecyl, makes it continuously dissolve from the surface of the solid particles and migrate to the surface of the hydrophobic fumed silica, while the grinding of hydrophobic fumed silica to sodium dodecyl sulfate solid particles during stirring breaks them up and significantly increases their specific surface area, further promoting the migration of sodium dodecyl sulfate to the surface of hydrophobic fumed silica, which can be observed macroscopically that the suspension of sodium dodecyl sulfate with a mass fraction of 60% and hydrophobic fumed silica forms a translucent stable homogeneous system after uniform stirring; such a process not only occurs in the solid surfactant-water system, but also occurs in the solid surfactant-liquid surfactant mixture system, for example, dodecyl trimethyl ammonium chloride (solid) is difficult to dissolve in anhydrous isomeric decanol polyoxyethylene ether 1007 (liquid) at room temperature, only a suspension can be formed, but the mixture of dodecyl trimethyl ammonium chloride with a mass fraction of 60% and anhydrous isomeric decanol polyoxyethylene ether 1007 also forms a translucent homogeneous system after uniform stirring with hydrophobic fumed silica.The hydrophilic surface active substance in liquid state described in the present application is not limited to "liquid state" or "solution" in a narrow sense. The adsorption can also occur in a mixture containing no surface active substance but having surface activity after mixing and being in liquid state, so that the mixture can also play the role of a surface active agent and form a water-dispersible sol with hydrophobic fumed silica. For example, titanate coupling agent 311W, which is a mixture of bis(dioctylpyrophosphato) ethylene titanate (insoluble in water, acidic, and having no surface activity) and triethanolamine (soluble in water, basic, and having no surface activity), is soluble in water and has weak surface activity. The surface activity is derived from the ion compound generated by the reversible transfer of the protons of bis(dioctylpyrophosphato) ethylene titanate to triethanolamine. The hydrophobic end of bis(dioctylpyrophosphato) ethylene titanate can be strongly adsorbed by hydrophobic fumed silica and anchored on the surface, but the adsorption of triethanolamine is weak, so that triethanolamine is more likely to chelate the protons of bis(dioctylpyrophosphato) ethylene titanate and relatively far away from the hydrophobic fumed silica. This action promotes the conversion of titanate coupling agent 311W to an ion compound and improves the surface activity. After the mixture of hydrophobic fumed silica and titanate coupling agent 311W is uniformly mixed, a nearly transparent yellow water-dispersible sol can be formed, which is dispersed in water to form a stable light yellow translucent dispersion. Therefore, the surface active substance in the hydrophilic surface active substance in liquid state described in the present application includes "a mixture containing no surface active substance but having surface activity after mixing and being in liquid state" rather than a "surface active agent" in a narrow sense. The strong adsorption of hydrophobic fumed silica to the lipophilic end of the surface active substance greatly widens the range of surface active substances that can be selected and makes it flexible and adjustable, and expands the application range of the water-dispersible sol of hydrophobic fumed silica.

[0111] For the mixture containing only hydrophobic fumed silica and liquid hydrophilic surfactant, the upper limit of the amount of hydrophobic fumed silica added is mainly subject to the situation that the viscosity of the mixture system rises to the point that it cannot be stirred evenly as the content of hydrophobic fumed silica increases, at which point the surface of the hydrophobic fumed silica in the system is not sufficient to adsorb all the surfactant used, and there is still a large amount of free surfactant that does not function, but the system has a very high viscosity that makes it impossible to add more hydrophobic fumed silica. In order to make the best use of the materials, the water-dispersible sol of the present application can also add oily substances according to different application requirements. On the one hand, the free surfactant can be fully utilized to emulsify and disperse the oily substances. When the sol is dispersed in water, the hydrophobic fumed silica is dispersed at the same time, and these oily substances can also be emulsified and dispersed into the coating, pigment, water-based film material, release agent, emulsion polymer, etc. system; on the other hand, these oily substances play a role in dilution and viscosity reduction in the water-dispersible sol, making it easier to disperse in water, or allowing further increase in the amount of hydrophobic fumed silica without increasing the amount of surfactant. As for the dispersion stability of oily substances, although as mentioned above, generally emulsifying an oily substance is only suitable for a very narrow range of surfactants around a certain HLB value that matches it, but in the stirring process of preparing the water-dispersible sol of the present application, the hydrophobic fumed silica particles play a strong grinding role, breaking the oily substance droplets to a small size with a large specific surface area that can adsorb a large amount of surfactant, making it difficult for oily substance droplets to aggregate and coalesce. In addition, a part of the oily substances are wrapped or infiltrated into the micropores of the hydrophobic fumed silica particles due to the strong adsorption of the hydrophobic fumed silica, forming a mixture particle with the outer surface mainly composed of hydrophobic fumed silica. By means of the adsorption of the lipophilic end of the surfactant by the hydrophobic fumed silica, the oily substance is combined with the surfactant, shielding the matching requirement of the HLB value of the surfactant by the oily substance itself. Thus, when the HLB value required for emulsification of the oily substance does not match the HLB value of the surfactant actually added, it can still maintain stability without segregation, and still remain stable after the water-dispersible sol is dispersed in water. This also expands the range of available oily substances, which is utilized by the present application to prepare a multifunctional water-dispersible sol. By adding this water-dispersible sol, a variety of different oily substances can be introduced, which can meet the application requirements in multiple fields.

[0112] The above examples are only used to illustrate the technical solutions of the present application and not to limit it. The technical solutions of the present application have been described in detail with reference to the preferred embodiments. Those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and all should be covered within the scope of the claims of the present application.

Claims

1. A water-dispersible sol of hydrophobic fumed silica, characterized in that, it is composed of raw materials in the following mass ratio: hydrophobic fumed silica: 25-70; oily substance: 0-300; co-emulsifier: 10-50; liquid-state hydrophilic surfactant: 100; the co-emulsifier includes one or more combinations of the following: a primary hydrocarbon alcohol with a melting point ≤ 70°C and a carbon atom number of 8-24, a primary hydrocarbon amine with a melting point ≤ 70°C and a carbon atom number of 8-18, triethanolamine, triisopropanolamine, tetrahydroxyethyl ethylenediamine, penta-hydroxyethyl diethylene triamine, triethanolamine borate, melamine substituted with 1-6 hydroxyethyl groups, tri-dan oil or tri-dan oil borate; the liquid-state hydrophilic surfactant includes one or more combinations of the following: an aqueous solution or aqueous suspension of a surfactant with a mass fraction ≥ 20%, a solution or suspension of a mixture of solid-state surfactants and liquid-state surfactants, a liquid-state surfactant, or a mixture containing non-surfactants but having surface activity and being in a liquid state after mixing; the HLB value of the liquid-state hydrophilic surfactant is ≥ 10.

2. The hydrophobic fumed silica aqueous dispersible sol according to claim 1, characterized in that, the oily substance includes one or more combinations of the following: a polyol fatty acid ester with a melting point ≤ 50°C, a non-aqueous non-aqueous reactive coating drying agent, a wax with a melting point ≤ 50°C, a surfactant with an HLB value ≤ 10, a non-aqueous non-aqueous reactive polymer monomer with a melting point ≤ 50°C, a polyalkylsiloxane with a viscosity ≤ 100 cst at 25°C, a polyolefin that is in a liquid state at room temperature with a viscosity ≤ 300 cst at 100°C, an epoxy resin with a viscosity ≤ 15000 mPa·s at 25°C, a fatty acid amide-based opening agent with a melting point ≤ 80°C, or an organic substance with a lipophilic group being a hydrocarbon with a carbon atom number ≥ 4 and a melting point ≤ 50°C.

3. A process for the preparation of an aqueous dispersible sol based on the hydrophobic fumed silica according to claim 1 or 2, characterized in that, including the following steps: separately weigh the following raw materials: 25-70 parts by mass of hydrophobic fumed silica, 0-300 parts by mass of oily substance, 10-50 parts by mass of co-emulsifier, and 100 parts by mass of liquid-state hydrophilic surfactant; mix the raw materials: put the weighed raw materials into a container, and the oily substance is put in first, followed by the co-emulsifier and the liquid-state hydrophilic surfactant; after each addition, stir until uniform before adding the next; after all the raw materials have been added, stir until fully mixed to obtain the water-dispersible sol of hydrophobic fumed silica.

4. The production method according to claim 3, characterized by, a vacuum defoaming treatment step is also included, which is performed after the raw materials are fully mixed; for sols containing water, the vacuum defoaming treatment is performed after cooling to room temperature.

5. The production method according to claim 3 or 4, characterized by, when the hydrophobic fumed silica is composed of two or more components, they are pre-mixed and stirred until uniform before being put in.

6. The production method according to claim 3 or 4, characterized by, When the oily substance contains a substance which is solid at room temperature, or the ambient temperature is too low to cause some components in the oily substance, the co-emulsifier or the liquid hydrophilic surface active substance to be difficult to stir due to too high viscosity or slow dissolution, then water bath heating at not higher than 70℃ is carried out during stirring, and the water bath heating is continued until the feeding is completed and the mixing is sufficient.

7. The production method according to claim 3 or 4, characterized by, For the oily substance which is unstable in air, CO2 protection or nitrogen protection is used during stirring.

8. A mixing method of the dispersoid sol prepared by the production method as claimed in claim 3 or 4, characterized by, The two or more water-dispersible sols of the hydrophobic fumed silica formed according to the method of claim 3 or claim 4, when their components are compatible, can be mixed with each other in any ratio, and after mixing, the mixture is still a water-dispersible sol of the hydrophobic fumed silica; the mixing includes direct mixing, or mixing after diluting the water-dispersible sol of the hydrophobic fumed silica into a hydrosol by adding water.

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