A highly water-repellent silicon-based micro-nano powder filler and preparation method thereof

Abstract

The present invention relates to a highly water-repellent silicon-based micro-nano powder filler and a preparation method thereof, comprising the following steps: first, siloxane monomer components are added to the reactor respectively; secondly, an aqueous solution of a hydrolysis medium, a water-carrying agent and a strong base catalyst is added in sequence, and then uniformly stirred and heated to react. After the reaction is completed, the temperature is continued to rise, and the amino-alkyl modified silicone resin is purified by vacuum distillation to obtain a amino-alkyl modified silicone resin. Subsequently, the amino-alkyl modified silicone resin, the modified epoxy resin and the nanoparticles according to a certain weight ratio are fully mixed and uniformly under a high-speed shear mixer, and then an emulsifier is added, and a stable emulsion system is prepared by reverse microemulsion polymerization, and a micro-nano powder filler is obtained after high-temperature ripening, suction filtration separation, washing, drying, grinding and sieving. The powder filler of the present invention has a static contact angle of up to 140° or more, and has excellent characteristics such as micro-nano structure, low surface energy and stable performance, and the reaction conditions are mild, energy-saving and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the fields of chemical industry and new organosilicon materials, and in particular to a highly water-repellent silicon-based micro-nano powder filler and a preparation method thereof. Background Art

[0002] Water repellency is widely used in biological systems, such as the self-cleaning mechanism of lotus and rice leaves. Water droplets can remove particles and pathogens from leaves, making them more resilient to chemical and biological damage. This effect, also known as hydrophobicity, has considerable advantages in many engineering applications. For example, low-cost water-repellent coatings that can produce self-cleaning building facades that resist biological deterioration, algae growth and general pollution will have significant advantages. Other important uses of hydrophobic coatings also include anti-biological hulls and marine infrastructure, anti-icing surfaces and corrosion resistance. At the same time, silicone resin materials are widely used in military, aerospace, petrochemical, machinery, construction, electric power and electrical appliances, automotive environmental protection, new energy and strategic emerging industries and other industrial fields and high-tech fields due to their excellent oxidation resistance, temperature and weather resistance, water repellency and chemical corrosion resistance. It is an important chemical environmentally friendly new material. Connecting the side chain of siloxane with a functional group with low surface energy can realize the synthesis of silicone resin with good water repellency, and further synthesize hydrophobic powder particles with special micro-nano structure and low specific surface energy on the surface, which has great application value in the field of wall building exterior walls and other surface protection of objects. In recent years, researchers have directly constructed micron-nano rough structures on the surface of objects or modified low surface energy substances on the rough solid surface by template etching, chemical vapor deposition and electrochemical methods to achieve surface hydrophobicity, but the above technologies still have large technical barriers, such as the inability to be applied on a large scale, and the inability to achieve large-scale industrial applications such as walls and building surfaces. At present, waterproof coatings produced by compounding water-repellent powder fillers with other materials are still the preferred way for industry applications. Therefore, it is an inevitable choice to directly synthesize low surface energy substances by chemical synthesis, and then form a certain micro-rough structure on the desired surface through process design to achieve high water repellency micro-nano powder fillers with both micro-nano structure and low specific surface energy.

[0003] The Chinese patent (CN104672962A) uses polymer nanoparticles such as polystyrene / polymethyl acrylate as a template, and the aqueous sol after hydrolysis of tetraethoxysilane hydrochloride as a mother liquor. The mother liquor is injected into the template to form a gel, and then the polymer microspheres are removed by calcination. The obtained powder is ground and modified with a silane coupling agent containing a hydrophobic group to obtain a super-hydrophobic powder with a micro-nano structure and modified with a low surface energy group. The method has complex steps and requires high-temperature heating above 600°C to remove the polymer template, which still poses difficulties in mass production.

[0004] Chinese patent (CN108384284A) utilizes nano-microsphere template reaction to prepare nanoparticle hydrogel, makes nanoparticle hydrogel dry and agglomerated in a constant temperature drying oven, finally grinds to obtain dry nanoparticle powder, then makes nanoparticle powder and liquid phase hydrophobic coupling agent reaction modification in the presence of catalyst, filters to obtain super-hydrophobic inorganic material powder. Although this method simplifies the steps, the required equipment is simple, and large-scale preparation can be achieved, but in reality, nanoparticles are modified with low surface energy materials by coupling reaction, thereby giving the powder material super-hydrophobic characteristics, in actual application scenarios, the stability of powder material is still insufficient, and the low surface energy materials of surface modification are easily destroyed. In addition, the silane coupling agent is selected as perfluorosiloxane, and its raw material cost is relatively high.

[0005] Chinese patent (CN111777736A) utilizes isocyanate and hydroxy silicone oil to add in tetrahydrofuran, stir at a certain temperature, condense and reflux in an inert gas atmosphere;Stop heating, after system temperature cools down, slowly add the tetrahydrofuran solution containing chain extender and catalyst mixed, continue stirring reaction in an inert gas atmosphere;After reaction terminates, the reaction product is poured into the precipitated phase, suction filtration is separated, the separated material is dried and ground, sieved, and super-hydrophobic powder material is obtained. Although the method simplifies step, required equipment is simple, but organic solvents can be used in large quantities in the whole reaction process, and it does not meet the concept of green environmental protection in large-scale production. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention proposes a preparation method that is simple, the industrial process is safe and efficient, and is friendly to the ecological environment. The material itself has the characteristics of micro-nano structure, low surface energy, and structural stability. The preparation method is carried out at room temperature and pressure and is easy to achieve large-scale production.

[0007] The technical solution of the present invention is as follows:

[0008] A highly water-repellent silicon-based micro-nano powder filler and a preparation method thereof are prepared by the following method: first, a colorless and transparent amino-alkyl modified silicone resin is prepared and synthesized by a siloxane monomer component under the action of a strong base catalyst. Subsequently, the amino-alkyl modified silicone resin, modified epoxy resin and nanoparticles in a certain weight ratio are fully mixed and uniformly in a high-speed emulsifying mixer, and an emulsifier is added, and deionized water is added drop by drop under high-speed shear dispersion. When the emulsified system is converted from a liquid to a solid oily body, hot water is poured into the reaction for a certain time so that the reaction system presents a stable emulsion system in a hot environment. After the reaction is completed, the emulsion system is heated to 120°C and stirred and matured for 2 hours to ensure that the silicone resin is completely solidified into powder particles, and a powder crude product is obtained by suction filtration separation, and then washed with ethanol, dried in a vacuum oven, and ground and sieved to obtain a highly water-repellent silicon-based micro-nano powder filler.

[0009] Further, the following steps are included:

[0010] Step S1, preparing aminoalkyl modified silicone resin: adding 1-70g siloxane, 1-20g deionized water, 1-30g hydrolysis medium, 1-10g water-carrying agent and 0.01-0.1g potassium hydroxide into a reactor protected by an inert atmosphere, stirring and reacting at 65°C to 85°C under alkaline conditions for 8h to 12h, and removing water and alcohol by reduced pressure distillation at 130°C to 140°C to obtain a colorless and transparent aminoalkyl modified silicone resin.

[0011] Step S2, preparing a stable emulsion by a reverse microemulsion method: taking 1-50 g of the aminoalkyl modified silicone resin obtained in step S1, 1-40 g of the modified epoxy resin and 0.01-0.5 g of nanoparticles according to a certain mass ratio, dispersing them by high-speed shearing at 1200-2200 r / min in the presence of 1-20 g of an emulsifier and simultaneously adding deionized water for phase transfer, adding 20-500 ml of 50° C. to 100° C. hot water for emulsification and self-assembly reaction for 4 to 8 hours to obtain a uniform and stable white emulsion system.

[0012] Step S3, post-treatment of the emulsion system: the white emulsion system of the above step S2 is heated to 120°C and stirred for 2h to 4h to ensure that the silicone resin is completely cured into micro-nano powder particles. After standing, the crude product is filtered and then washed three times with anhydrous ethanol, vacuum dried at 70°C for 12h, and ground through a 400-mesh sieve to obtain highly water-repellent micro-nano powder particles.

[0013] Furthermore, the siloxane monomers are of the following types: difunctional chain siloxanes: trifluoropropylmethylcyclotrisiloxane (D3F), diphenyldimethoxy (or ethoxy) silane, N-aminoethyl-γ-aminopropylmethyldimethoxysilane (KH-602) and octamethyltrisiloxane, etc.; trifunctional chain siloxanes: perfluoroalkyl (C7-C12) trimethoxy (or ethoxy) silane, phenyltrimethoxy (or ethoxy) silane and γ-aminopropyltrimethoxysilane (KH-550), etc.; end-capped siloxanes: pentamethyldisiloxane, hexamethyldisiloxane and octamethyltrisiloxane, etc.; formed by hydrolysis and condensation of three or more of them.

[0014] Furthermore, the hydrolysis medium is a low boiling point organic solvent with a boiling point between 50° C. and 140° C., such as acetone, cyclohexane, toluene or xylene, etc., a single or mixed organic solvent.

[0015] Furthermore, the strong base catalyst may be a mixture of one or more of sodium hydroxide, potassium hydroxide and other water-soluble strong base catalysts.

[0016] Furthermore, in the reverse microemulsion method, the ratio of the active hydrogen value of the amino-alkyl modified silicone resin to the epoxy value in the epoxy resin is 0.85-0.96:1 (mol / 100g), the content of nanoparticles accounts for 0.1%-0.5% (mass), the amount of deionized water added is 30%-45% of the total mass of the resin, the temperature of adding hot water is 50°C-100°C, and the mass of the hot water is 8-10 times the total mass of the amino-alkyl modified silicone resin and the epoxy resin.

[0017] Furthermore, the emulsifier is used in an amount of 5% to 20% of the weight of the reactants, and is any water-soluble nonionic emulsifier with a hydrophile-lipophile balance (HLB) value between 9 and 16.

[0018] Furthermore, the nanoparticles in the reverse microemulsion method are single or combined nanoparticles such as nano-silicon dioxide, nano-titanium dioxide and nano-calcium carbonate.

[0019] The present invention also includes a highly water-repellent silicon-based micro-nano powder filler prepared by the above steps.

[0020] The present invention has the following excellent characteristics:

[0021] 1. The highly water-repellent silicon-based micro-nano powder filler and the preparation method thereof provided by the present invention have the following characteristics: the preparation method has simple steps, the industrial process is safe and efficient, and is friendly to the ecological environment;

[0022] 2. The material itself has a micro-nano structure, low surface energy and stable structure, mild reaction conditions, energy saving and environmental protection, and the prepared silicon-based micro-nano powder filler has stable performance.

[0023] 3. The introduction of amino hydrocarbon-modified silicone resin gives the nano-powder filler more excellent properties, such as oxidation resistance, temperature and weather resistance, hydrophobicity and chemical corrosion resistance. The highly hydrophobic silicon-based micro-nano powder filler prepared by this method can be used in more engineering fields with hydrophobic requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the hydrolysis and condensation reaction mechanism of organic silicon monomer and the polymerization mechanism diagram of epoxy resin and amino hydrocarbon modified silicone resin;

[0025] Figure 2 This is a sample picture of highly water-repellent silicon-based micro-nano powder filler;

[0026] Figure 3 This is a diagram showing the apparent hydrophobic effect of highly water-repellent silicon-based micro-nano powder filler;

[0027] Figure 4 This is the SEM microscopic morphology of highly water-repellent silicon-based micro-nano powder filler;

[0028] Figure 5 The infrared spectra of the amino-hydrocarbon modified silicone resin prepared by hydrolysis and condensation of organic silicon monomers and the highly water-repellent silicon-based micro-nano powder filler prepared by reverse microemulsion polymerization;

[0029] Figure 6 The contact angle test diagram of the highly water-repellent silicon-based micro-nano powder filler of Examples 1-4. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1:

[0032] Step S1, preparing aminoalkyl modified silicone resin: under nitrogen protection, add 27g of trifluoropropylmethylcyclotrisiloxane (D3F); 11g of diphenyldiethoxysilane; 9g of dimethyldiethoxysilane; 3g of γ-aminopropyltrimethoxysilane (KH-550); 13g of octamethyltrisiloxane; 0.01g of potassium hydroxide; 25g of toluene, and 5g of xylene to the reactor respectively. Then, 0.01g of potassium hydroxide is dissolved in 15g of deionized water, stirred and added to the reactor, heated to 70°C and reacted for 12 hours, then the system is slowly heated to 130°C and distilled under reduced pressure to remove low-boiling substances and water generated by the hydrolysis and condensation reaction, to obtain a colorless and transparent aminoalkyl modified silicone resin.

[0033] Step S2, preparing a uniform emulsion by reverse microemulsion method: taking 20g of amino hydrocarbon modified silicone resin obtained in step S1, 10g of aliphatic epoxy resin and 0.1g of nano silicon dioxide (Hy-SiO2), and dispersing them by 1500r / min high-speed shearing under 6g of non-ionic emulsifier OS-15. When the amount of deionized water added is 9g, a phase inversion phenomenon occurs, that is, the emulsified system is transformed from a liquid to a solid oily body. At this time, 280ml of 100°C hot water is added for emulsification self-assembly reaction for 4 hours or more to obtain a uniform and stable emulsion system.

[0034] Step S3, post-treatment of the emulsion system: the white emulsion system of step S2 is heated to 120°C and stirred for 2 hours to ensure that the silicone resin is completely solidified into micro-nano powder particles. After standing, the crude product is filtered and then washed three times with anhydrous ethanol, vacuum dried at 70°C for 12 hours, and ground through a 400-mesh sieve to obtain highly water-repellent micro-nano powder particles.

[0035] The powder material was pressed into a flat block by a tablet press, and then the contact angle of a water drop on the surface of a highly hydrophobic silicon-based micro-nano powder filler was measured using a contact angle meter. The drop volume was set to 10 μL, and the contact angle was measured after the water drop remained in a stable state on the surface of the highly hydrophobic silicon-based micro-nano powder filler for 30 seconds. The contact angles of the same sample were measured at three different positions, and the average static contact angle value was calculated to be 143.3°.

[0036] Embodiment 2:

[0037] A highly water-repellent silicon-based micro-nano powder filler and a preparation method thereof are prepared by the following steps:

[0038] Step S1, preparing aminoalkyl modified silicone resin: under nitrogen protection, add 27g of trifluoropropylmethylcyclotrisiloxane (D3F); 8g of diphenyldiethoxysilane; 10g of dimethyldiethoxysilane; 5g of γ-aminopropyltrimethoxysilane (KH-550); 13g of octamethyltrisiloxane; 0.01g of potassium hydroxide; 25g of toluene, and 5g of xylene to the reactor respectively. Then, 0.01g of potassium hydroxide is dissolved in 15g of deionized water, stirred and added to the reactor, and the temperature is raised to 70°C for reaction for 12 hours, and the system is slowly heated to 130°C and distilled under reduced pressure to remove low-boiling substances and water generated by the hydrolysis and condensation reaction, to obtain a colorless and transparent aminoalkyl modified silicone resin.

[0039] Step S2, preparing a uniform emulsion by reverse microemulsion method: taking 25g of amino hydrocarbon modified silicone resin obtained in step S1, 13g of aliphatic epoxy resin and 0.15g of nano silicon dioxide (Hy-SiO2), and dispersing them by 1500r / min high-speed shearing under 7.6g of non-ionic emulsifier OS-15. When the amount of deionized water added was 11.5g, a phase inversion phenomenon occurred, that is, the emulsified system was transformed from a liquid to a solid oily body. At this time, 360ml of 100°C hot water was added for emulsification self-assembly reaction for 4 hours or more to obtain a uniform and stable emulsion system.

[0040] Step S3, post-treatment of the emulsion system: the white emulsion system of step S2 is heated to 120°C and stirred for 2 hours to ensure that the silicone resin is completely solidified into micro-nano powder particles. After standing, the crude product is filtered and then washed three times with anhydrous ethanol, vacuum dried at 70°C for 12 hours, and ground through a 400-mesh sieve to obtain highly water-repellent micro-nano powder particles.

[0041] The powder material was pressed into a flat block by a tablet press, and then the contact angle of the water droplet on the surface of the highly hydrophobic silicon-based micro-nano powder filler was measured using a contact angle meter. The water droplet volume was set to 10 μL, and the contact angle was measured after the water droplet remained in a stable state on the surface of the highly hydrophobic silicon-based micro-nano powder filler for 30 seconds. The contact angle of the same sample was measured at three different positions, and the average static contact angle value was calculated to be 141.4°.

[0042] Embodiment three:

[0043] A highly water-repellent silicon-based micro-nano powder filler and a preparation method thereof are prepared by the following steps:

[0044] Step S1, preparing aminoalkyl modified silicone resin: under nitrogen protection, add 27g of trifluoropropylmethylcyclotrisiloxane (D3F); 9g of diphenyldiethoxysilane; 12g of dimethyldiethoxysilane; 3g of γ-aminopropyltrimethoxysilane (KH-550); 12g of octamethyltrisiloxane; 0.01g of potassium hydroxide; 25g of toluene, and 5g of xylene to the reactor respectively. Then, 0.01g of potassium hydroxide is dissolved in 15g of deionized water, stirred and added to the reactor, heated to 70°C and reacted for 12 hours, then the system is slowly heated to 130°C and distilled under reduced pressure to remove low-boiling substances and water generated by the hydrolysis and condensation reaction, to obtain a colorless and transparent aminoalkyl modified silicone resin.

[0045] Step S2, preparing a uniform emulsion by reverse microemulsion method: 19g of amino hydrocarbon modified silicone resin obtained in step S1, 9g of aliphatic epoxy resin and 0.07g of nano silicon dioxide (Hy-SiO2) were taken and dispersed by high-speed shear at 1500r / min under 4.2g of non-ionic emulsifier OS-15. When the amount of deionized water added was 8.6g, a phase inversion phenomenon occurred, that is, the emulsified system was transformed from a liquid to a solid oily body. At this time, 270ml of 100°C hot water was added for emulsification self-assembly reaction for 4 hours or more to obtain a uniform and stable emulsion system.

[0046] Step S3, post-treatment of the emulsion system: the white emulsion system of step S2 is heated to 120°C and stirred for 2h to 4h to ensure that the silicone resin is completely cured into micro-nano powder particles. After standing, the crude product is filtered and then washed three times with anhydrous ethanol, vacuum dried at 70°C for 12h, and ground through a 400-mesh sieve to obtain highly water-repellent micro-nano powder particles.

[0047] The powder material was pressed into a flat block by a tablet press, and then the contact angle of a water drop on the surface of a highly hydrophobic silicon-based micro-nano powder filler was measured using a contact angle meter. The drop volume was set to 10 μL, and the contact angle was measured after the water drop remained in a stable state on the surface of the highly hydrophobic silicon-based micro-nano powder filler for 30 seconds. The contact angles of the same sample were measured at three different positions, and the average static contact angle value was calculated to be 140.8°.

[0048] Embodiment 4:

[0049] A highly water-repellent silicon-based micro-nano powder filler and a preparation method thereof are prepared by the following steps:

[0050] Step S1, preparing aminoalkyl modified silicone resin: under nitrogen protection, add 27g of trifluoropropylmethylcyclotrisiloxane (D3F); 7g of diphenyldiethoxysilane; 9g of dimethyldiethoxysilane; 7g of γ-aminopropyltrimethoxysilane (KH-550); 12g of octamethyltrisiloxane; 0.01g of potassium hydroxide; 25g of toluene, and 5g of xylene to the reactor respectively. Then, 0.01g of potassium hydroxide is dissolved in 15g of deionized water, stirred and added to the reactor, heated to 70°C and reacted for 12 hours, then the system is slowly heated to 130°C and distilled under reduced pressure to remove low-boiling substances and water generated by the hydrolysis and condensation reaction, to obtain a colorless and transparent aminoalkyl modified silicone resin.

[0051] Step S2, preparing a uniform emulsion by reverse microemulsion method: taking 24g of amino hydrocarbon modified silicone resin obtained in step S1, 11g of aliphatic epoxy resin and 0.14g of nano silicon dioxide (Hy-SiO2), and dispersing them by 1500r / min high-speed shearing under 6.5g of non-ionic emulsifier OS-15. When the amount of deionized water added was 10.8g, a phase inversion phenomenon occurred, that is, the emulsified system was transformed from a liquid to a solid oily body. At this time, 320ml of 100°C hot water was added for emulsification self-assembly reaction for 4 hours or more to obtain a uniform and stable emulsion system.

[0052] Step S3, post-treatment of the emulsion system: the white emulsion system of step S2 is heated to 120°C and stirred for 2h to 4h to ensure that the silicone resin is completely cured into micro-nano powder particles. After standing, the crude product is filtered and then washed three times with anhydrous ethanol, vacuum dried at 70°C for 12h, and ground through a 400-mesh sieve to obtain highly water-repellent micro-nano powder particles.

[0053] The powder material was pressed into a flat block by a tablet press, and then the contact angle of a water drop on the surface of a highly water-repellent micro-nano powder particle was measured using a contact angle meter. The volume of the water drop was set to 10 μL, and the contact angle was measured after the water drop remained stable on the surface of the highly water-repellent micro-nano powder particle for 30 seconds. The contact angle of the same sample was measured at three different positions, and the average static contact angle value was calculated to be 141.1°.

[0054] Next, the highly water-repellent micro-nano powder particles prepared in Examples 1-4 were subjected to microscopic morphology test, infrared test, and surface contact angle test:

[0055] 1. Microscopic morphology test

[0056] The microscopic size of highly water-repellent micro-nano powder particles was observed at the micrometer scale by scanning electron microscopy. The specific method is: highly water-repellent micro-nano powder particles are dispersed in ethanol, maintaining a concentration of 0.5%. Then, they are dripped onto a glass sheet with a dropper, dried thoroughly in an oven, and then subjected to gold spraying treatment and the morphology is observed under a scanning electron microscope.

[0057] like Figure 4 In the SEM image shown, the synthesized highly water-repellent micro-nano powder particles are distributed relatively evenly. Since the size of the nanoparticles is at the nanoscale, the ratio of the surface to the volume is greatly increased, and the surface energy of the particles is greatly increased, resulting in agglomeration between a small number of particles. At the same time, the synthesized powder particles have various shapes, some are spherical, some are polyhedral, but most are irregular. Under the nucleation of nanoparticles, the powder particles synthesized by coating with silicone-based resin are significantly larger in particle size than nanoparticles. Through observation under a scanning electron microscope, it can be found that the particle size is uneven, with both micron-sized particles and nano-sized particles, indicating that highly water-repellent micro-nano powder particles have been successfully synthesized.

[0058] 2. Infrared test

[0059] Test method: After the highly hydrophobic silicon-based micro-nano powder filler is fully dried, 1 mg of solid powder sample and 100 mg of dried pure KBr solid particles are taken with a special sampling spoon for infrared testing. Mix and grind them fully in an agate mortar to a particle size of several microns, and bake them under an infrared baking lamp for 3 minutes. Then add the powder to the tablet pressing mold, set the press pressure to 12-14 MPa, maintain the pressure for 30 seconds, and finally demold to obtain a light-transmitting thin sample. The sample is placed in a Fourier transform infrared spectrometer (Nicolet-is5, Thermo Fisher Scientific) to measure the sample infrared spectrum.

[0060] like Figure 5 The following are infrared spectra of amino-alkyl modified silicone resin prepared by hydrolysis and condensation of siloxane monomer, modified epoxy resin and highly water-repellent micro-nano powder particles prepared by reverse microemulsion polymerization. In the infrared spectrum of amino-alkyl modified silicone resin, at 3500cm -1 and 1206cm -1 There are relatively weak and strong -NH absorption vibration peaks at 1367cm -1 and 1062cm -1 There are absorption vibration peaks of -CF and -Si-O- respectively, indicating that the synthetic product contains amino groups that can react with epoxy and low surface energy substances, so it has water repellency, and also indicates that amino hydrocarbon modified silicone resin with silicon oxygen bond as the main body is synthesized. -1 and 910cm -1 The obvious absorption peak at 3425cm belongs to the absorption vibration peak of -C=O and the absorption vibration peak unique to the epoxy group, indicating that the epoxy resin can further undergo polymerization with the above-mentioned amino-alkyl modified silicone resin. -1and 2937cm -1 The broad absorption vibration peaks of -OH and -CH2- appearing at also indicate that the highly hydrophobic micro-nano powder particles have low surface energy groups and therefore have high hydrophobicity; at the same time, the weakening of the amino and epoxy group peaks indicates that the reverse microemulsion polymerization method is successful.

[0061] 3. Surface contact angle test

[0062] Test method: The highly hydrophobic silicon-based micro-nano powder filler is pressed into a flat block by a tablet press using a physical pressing method, and then the contact angle of the water drop on the highly hydrophobic surface is measured using a contact angle meter. The drop volume is set to 10μL, and the water drop remains in a stable state on the surface of the highly hydrophobic silicon-based micro-nano powder filler for 30 seconds before the contact angle is measured. The contact of the same sample is measured at three different positions, and the average value is taken as the final hydrophobic angle of the sample.

[0063] like Figure 6 In the surface contact angle diagram shown, the synthesized highly water-repellent micro-nano powder particles have good water-repellent properties. The static contact angles of the highly water-repellent micro-nano powder particles prepared in Examples 1-4 are all greater than 140°.

[0064] The embodiments described above are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing highly water-repellent silicon-based micro-nano powder filler, It is characterized in that The following steps are involved: Step S1) preparing amino-alkyl modified silicone resin: adding 1-70g of siloxane monomer, 1-20g of deionized water, 1-30g of hydrolysis medium, 1-10g of water-carrying agent and 0.01-0.1g of strong base catalyst into a reactor protected by an inert atmosphere, stirring and reacting at 65°C to 85°C under alkaline conditions for 8h to 12h, and then removing water and alcohol by reduced pressure distillation at 130°C to 140°C to obtain a colorless and transparent amino-alkyl modified silicone resin; Step S2) preparing a stable emulsion by a reverse microemulsion method: taking 1-50 g of the aminoalkyl modified silicone resin obtained in step S1), 1-40 g of the modified epoxy resin and 0.01-0.5 g of nanoparticles according to a certain mass ratio, dispersing them by high-speed shearing at 1200-2200 r / min under the condition of 1-20 g of emulsifier and simultaneously adding deionized water for phase transfer, and when the emulsified system is converted from a liquid to a solid oily body, adding 20-500 ml of hot water at a temperature of 50° C. to 100° C. for emulsification self-assembly reaction for 4 to 8 hours to obtain a uniform and stable white emulsion system; Step S3) post-treatment of the emulsion system: the white emulsion system of the above step S2) is heated to 120°C and stirred for 2h to 4h to ensure that the silicone resin is completely cured into micro-nano powder particles. After standing, the crude product is filtered and then washed three times with anhydrous ethanol, dried in vacuo at 70°C for 12h, and ground through a 400-mesh sieve to obtain highly water-repellent micro-nano powder particles.

2. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 1, It is characterized in that The siloxane monomers are of the following types: 1) Difunctional chain siloxane: trifluoropropylmethylcyclotrisiloxane, diphenyldimethoxysilane, diphenyldiethoxysilane, N-aminoethyl-γ-aminopropylmethyldimethoxysilane and octamethyltrisiloxane; 2) Trifunctional chain siloxanes: perfluoroalkyl trimethoxysilane, trifunctional chain siloxane perfluoroalkyl triethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane and γ-aminopropyl trimethoxysilane; 3) End-capped siloxane: pentamethyldisiloxane, hexamethyldisiloxane and octamethyltrisiloxane; the siloxane monomer is composed of a random combination of three or more of the above.

3. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 2, It is characterized in that The water-carrying agent is xylene.

4. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 3, It is characterized in that The hydrolysis medium is a low boiling point organic solvent with a boiling point between 50°C and 140°C.

5. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 4, It is characterized in that The organic solvent is a single or mixed organic solvent of acetone, cyclohexane, toluene or xylene.

6. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 5, It is characterized in that The strong base catalyst is a mixture of one or more of sodium hydroxide, potassium hydroxide and other water-soluble strong base catalysts.

7. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 6, It is characterized in that In step S2), the ratio of the active hydrogen value of the amino-alkyl modified silicone resin to the epoxy value in the modified epoxy resin is 0.85-0.96:1 mol / 100g, the content of the nanoparticles accounts for 0.1%-0.5% by weight, the amount of deionized water added is 30%-45% of the total mass of the resin, and the mass of the hot water is 8-10 times the total mass of the resin.

8. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 7, It is characterized in that The emulsifier is any water-soluble nonionic emulsifier with a hydrophilic-lipophilic balance value between 9 and 16; the amount of the emulsifier is 5% to 20% of the mass of the reactants.

9. The method for preparing the highly water-repellent silicon-based micro-nano powder filler according to claim 8, It is characterized in that The nanoparticles in the reverse microemulsion method are single or combined nanoparticles of nano-silicon dioxide, nano-titanium dioxide and nano-calcium carbonate.

10. A highly water-repellent silicon-based micro-nano powder filler, It is characterized in that The highly water-repellent silicon-based micro-nano powder filler is prepared by the preparation method described in claim 1.

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