CN101274762A - Modification method for silicon dioxide aerogel - Google Patents
Modification method for silicon dioxide aerogel Download PDFInfo
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- CN101274762A CN101274762A CNA2007100890785A CN200710089078A CN101274762A CN 101274762 A CN101274762 A CN 101274762A CN A2007100890785 A CNA2007100890785 A CN A2007100890785A CN 200710089078 A CN200710089078 A CN 200710089078A CN 101274762 A CN101274762 A CN 101274762A
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Abstract
The invention relates to a method for modifying silicon dioxide aerogel. The method of the invention is characterized in that the nature of the azeotropy of C4 to C10 aliphatic alcohols and water under the constant temperature is utilized for removing free water in the silicon dioxide wet gel; the esterification reaction of alcohol and hydroxyl on the surface of silicon dioxide is utilized for the surface finishing and modification of the silicon dioxide aerogel so as to obtain water repellent products; wherein, the mass ratio of the silicon dioxide, the water, the a lcohol and a catalyst is 1: (8.0 to 9.5): (10 to 20): (0.01 to 0.05) and the catalyst is alkyl-sulfuric acid, alkyl sulfate or alkyl sulphate ion, aryl sulfonic acid, aryl-sulphonate or aryl-sulphonate ion. The invention also relates to the silicon dioxide aerogel obtained by the method and the surface of the silicon dioxide aerogel is dehydrated and contains aliphatic groups.
Description
Technical field
The invention belongs to inorganic powder material process for modifying surface field, particularly relate to a kind of drying and dehydrating and hydrophobically modified method of silica wet gel.
Background technology
SiO
2Aerogel is the nano-meter porous amorphous solid material of a kind of lightweight, has characteristics such as density is little, specific surface area is high, pore volume is big, specific refractory power is adjustable, thermal conductivity is low, the acoustic resistance Chinese People's Anti-Japanese Military and Political College, good insulating, is widely used in fields such as optics, calorifics, acoustics, electricity.Yet, the activated silica hydroxyl that the poly-silica of silicon-dioxide inside and outside surface exist is planar water extremely, make it present wetting ability, in organic phase, be difficult to wetting and dispersion, and because there is hydroxyl in its surface, surface energy is bigger, aggregate always tends to cohesion, thereby the application performance of product is affected.For example, be difficult to homodisperse when in paint, being used as matting agent, easily coagulative precipitation; As paper additive the time, the printing ink adsorptive power is not good etc., for this reason, need carry out surface modification to silicon-dioxide powdery, to improve its effect.
Silica wet gel is in drying process, and the particulate surface portion exposes out gradually.Water vapour is then gone out from the two ends of hole, like this because the existence of capillary force, in water, form quiet stretching pressure, it can cause the contraction of kapillary hole wall, thereby make the particle contact closely, along with further removing of water, the non-bridge formation hydroxyl of adjacent micelle gets final product the spontaneous bridge formation hydroxyl that changes into, and the part-structure coordinated water in the gel removed, and form hard aggregation.For overcoming this phenomenon, employing supercritical technologies such as Chinese patent 03127920.1,200310117210.0 carry out drying to wet gel, but because equipment, technology and cost are limit, this method is difficult to volume production.
Silica wet gel is carried out surface modification sillylation reagent commonly used has the chlorosilane class (as Chinese patent application numbers 98811524.0,03820279.4,200510011144.8 etc.), type siloxane (as Chinese patent 97181109.1,98811524.0 etc.) etc.Use chlorosilane will produce a large amount of HCl and various relevant therewith by product inevitably, in case of necessity, need make water and appropriate organic solvent repetitive scrubbing so that silylanizing SiO
2Purifying has increased production cost, simultaneously the equipment erosion resistance is proposed higher requirement.Type siloxane need add HCl as catalyzer, therefore also has same problem.
Summary of the invention
The dehydration and the modification technology that the purpose of this invention is to provide a kind of technology aerosil simple, with low cost.
Its technical characterictic of the dehydration of aerosil of the present invention and modification technology is: utilize fatty alcohol and water azeotropic character under constant temp to remove free water in the silica wet gel, to eliminate the hard aggregation phenomenon that silicon-dioxide causes because of dehydration in the conventional drying process.After water disappears, add catalyzer simultaneously, utilize fatty alcohol and silica sphere hydroxyl generation esterification, finally reach surface modified effect.
Therefore, the invention provides a kind of like this dehydration and method of modifying of aerosil, comprise fatty alcohol and silica wet gel are carried out component distillation, to remove the free water in the silica wet gel; Make hydroxyl generation esterification on described fatty alcohol and the silica sphere by adding catalyzer then, to carry out surperficial modification.
In addition, the present invention also provides a kind of aerosil that obtains by above-mentioned method, and its surface is dehydrated and contains aliphatic group, thus the hydrophobicity of showing.
The silica wet gel that the present invention uses can be prepared by the art methods of routine or obtain from the market purchase, for example can buy from Tianjin chemical research institute obtain.
The fatty alcohol that the present invention uses for example can be C4～C10 fatty alcohol according to selecting with the requirement that water carries out component distillation, preferred C4～C8 fatty alcohol, especially C8 fatty alcohol.
The catalyzer that uses in the above-mentioned hydroxyl generation esterification that makes on described fatty alcohol and the silica sphere can be to have formula R-SO
3H or R-SO
4The alkylsurfuric acid of H, alkyl-sulphate, aryl sulfonic acid or arylsulphonate.Its example has p-methyl benzenesulfonic acid etc.
The add-on of catalyzer is to treat 0.1～5% of modification wet gel quality, and catalyzer can be with adding behind the appropriate organic solvent dissolved dilution.Appropriate organic solvent can be organic solvents commonly used such as C1～C4 alcohol, acetone, ether, benzene, toluene and sherwood oil.
In the dehydration of the inventive method, utilize pure water azeotropic properties to remove free water in the silica wet gel, wherein the quality ratio of silicon-dioxide, water, alcohol for example is 1: (8.0～9.5): (10～20).And the esterification of utilizing alcohol and silica sphere hydroxyl in the presence of catalyzer, to take place subsequently, surface modified aerosil obtains hydrophobic product.
Temperature is usually 70-100 ℃ scope in above-mentioned pure water azeotropic process, preferably 90-100 ℃ scope, and for example about 99 ℃.The alcohol water common time length of azeotropic process changes for the situation according to the Fatty Alcohol(C12-C14 and C12-C18) that uses, and it is enough to the dehydration of the free water content on the silica sphere up to for example below 1% weight.
After above-mentioned modification finished, unnecessary properties-correcting agent and catalyzer were removed in water or appropriate organic solvent washing, and oven dry is pulverized, and promptly gets product.
Embodiment
According to a specific embodiments of the present invention, the concrete steps of dehydration modification are as follows:
1, will synthesize or buy the silica wet gel filtration of acquisition or the wet cake that press filtration becomes moisture 80～95% (quality).
2, wet cake is immersed in C4～C10 fatty alcohol, the volumetric ratio of water-content is in the add-on of alcohol and the wet cake: (0.1～10): 1.Heterogeneous system is stirred.
3, continuously stirring heterogeneous system and heating, when reaching the azeotropic temperature of water and alcohol, water steams with constant volume ratio azeotropic with alcohol, and system temperature is constant, remains liquid level in the heat-processed and is higher than solid phase, if then continue to add alcohol inadequately.Behind gained vapor condensation standing demix, oil phase can recycle.
4, when raising above azeotropic temperature, continues system temperature heating 1～100min, to add after with organic solvent diluting as the p-methyl benzenesulfonic acid of catalyzer then, consumption is 0.1～20% of a wet cake massfraction, for preventing the catalyzer decomposes, system temperature can be reduced in case of necessity behind the suitable temp and add again.Keep temperature of reaction at 40～190 ℃, the reaction times is 0.1～48h.
5, reaction finishes back water or ethanol or the unnecessary pure and mild catalyzer of petroleum ether alcogel removal, and filtering drying obtains product.
Description of drawings
Fig. 1 is the contact angle of water on modification sample of the present invention.
Fig. 2 is the infrared spectra of modification sample of the present invention.
Fig. 3 is the infrared spectra of the unmodified sample of the present invention.
Fig. 4 is the thermogravimetric analysis curve of modification sample of the present invention.
Fig. 5 is the BJH graph of pore diameter distribution of modification sample of the present invention.
Fig. 6 is the stereoscan photograph of modification sample of the present invention.
By the aeroge sample rate of modification of the present invention at 100～500kg/m3, floating on the water surface It is nonwetting not sink in 30 days, and the contact angle of water on the aeroge surface is 127～144 degree (seeing Fig. 1). The infrared spectrum of sample (seeing Fig. 2), near the absworption peak 2936cm-1 and 2858cm-1 is-CH3With-CH2The stretching vibration of middle c h bond illustrates that the aeroge surface has connected octyloxy group, with The infrared spectrum of unmodified sample (seeing Fig. 3) is compared, and constitution water is at 3440cm-1 and 1630cm-1 The all little and unmodified sample near stretching vibration peak and flexural vibrations peak illustrates that modification can remove section The constitution water that divides silica surface. The TG-DTA curve (seeing Fig. 4) of sample in the time of 295 ℃, An exothermic peak occurs, quality reduces 1% simultaneously, and this is that the octyloxy decomposes is CO2And H2O Emit heat. Adsorb the BJH pore volume at 1.8～3.0cm at nitrogen3/ g (ASAP 2010 measures), the hole branch Cloth is narrow, and average pore size (is seen Fig. 5) between 15～30nm, and product presents cellular porous Structure (seeing Fig. 6, sample SEM electromicroscopic photograph).
The advantage that can realize by the present invention is:
1, adopts pure water azeotropic distillation dehydration, can prevent effectively that aerosil is when drying Agglomeration, keep the primary pattern of aeroge.
2, dehydration is combined with modifying process, and a step finishes, and simplifies production technology, is easy to industry and amplifies Produce. The cost of preparation aerosil is starkly lower than traditional supercritical process, and produces The product quality reaches or near the supercritical process product.
3, modifier reclaims conveniently, can be recycling, further reduce the industrial production cost.
4, modification speed, modified effect is good, when serviceability temperature is lower than 250 ℃, has good Good hydrophobic performance.
The method of modifying that the invention is further illustrated by the following examples, but not limitation is therewith.
Take by weighing the silica wet gel of 100g moisture 90%, add the 100ml n-Octanol, mixing and stirring, reflux, when temperature was elevated to 99.4 ℃, n-Octanol and water steamed according to 20: 80 azeotropic of volume ratio, derive steam, the condensation standing demix, oil phase can be recycled.When temperature was elevated to 110 ℃, system no longer included a large amount of steam and steams, and water removes substantially and finishes, and added 110 ℃ of isothermal reactions four hours after the 1g p-methyl benzenesulfonic acid is dissolved in the 50ml n-Octanol.Reaction finishes postcooling filters, and with petroleum ether twice, 105 ℃ of dryings 20 hours, obtains aerosil.
Embodiment 2
Change the initial add-on of n-Octanol among the embodiment 1 into 200ml, the amount of p-methyl benzenesulfonic acid changes 0.5g into, and modification temperature is at 130 ℃, and cleaning solvent changes ethanol into.All the other operations are the same.
Embodiment 3
Change the initial add-on of n-Octanol among the embodiment 1 into 250ml, the amount of p-methyl benzenesulfonic acid changes 0.3g into, and modification temperature is at 150 ℃, and cleaning solvent changes water into.All the other operations are the same.
Change p-methyl benzenesulfonic acid among the embodiment 2 into adding Witco 1298 Soft Acid 0.5g, all the other operations are the same.
Embodiment 5
Change p-methyl benzenesulfonic acid among the embodiment 2 into adding dodecyl sulphate 1g, all the other operations are the same.
Claims (10)
1. the dehydration of an aerosil and method of modifying is characterized in that comprising fatty alcohol and silica wet gel are carried out component distillation, to remove the free water in the silica wet gel; Make hydroxyl generation esterification on described fatty alcohol and the silica sphere by adding catalyzer then.
2. according to the method for claim 1, it is characterized in that:
(1) component distillation under azeotropic temperature with silica wet gel and fatty alcohol is deviate from the free water in the wet gel, and wherein the weight ratio of silicon-dioxide, water, alcohol is 1: (8.0～9.5): (10～20);
(2) after dehydration finishes, add catalyzer and carry out modified-reaction, modification temperature raises on the basis of pure water azeotropic temperature or reduces by 50 ℃ with interior scope, and modification time continues 1～4 hour.
3. according to the method for claim 1 or 2, it is characterized in that described fatty alcohol is C4～C10 fatty alcohol, preferred C4～C8 fatty alcohol, particularly C8 fatty alcohol.
4. according to the method for claim 1 or 2, it is characterized in that modified catalyst is for having formula R-SO
3H or R-SO
3The alkylsurfuric acid of H, alkyl-sulphate, alkyl sulfate ion, aryl sulfonic acid, arylsulphonate or aryl sulfonic acid radical ion.
5. according to the method for claim 1 or 2, the add-on that it is characterized in that catalyzer is 0.1～5% of a modification wet gel quality,
6. according to the method for claim 1 or 2, it is characterized in that catalyzer adds with organic solvent dissolution dilution back.
7. according to the method for claim 6, it is characterized in that organic solvent is organic solvents such as C1～C4 alcohol, acetone, ether, benzene, toluene and sherwood oil.
8. according to the method for claim 1 or 2, it is characterized in that modification finishes the back water or organic solvent washing is removed unnecessary properties-correcting agent and catalyzer, oven dry is pulverized, and promptly gets product.
9. the method for claim 8 is characterized in that organic solvent is organic solvents such as C1～C4 alcohol, acetone, ether, benzene, toluene and sherwood oil.
10. aerosil that obtains by each method of claim 1-9, its surface is dehydrated and contains aliphatic group.
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| CNA2007100890785A CN101274762A (en) | 2007-03-29 | 2007-03-29 | Modification method for silicon dioxide aerogel |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101837982A (en) * | 2010-03-19 | 2010-09-22 | 福建师范大学 | Method for preparing silicon dioxide aerogel powder |
| CN102199378A (en) * | 2011-03-21 | 2011-09-28 | 冷水江三A化工有限责任公司 | Preparation method for silica aerogel flatting agent |
| CN106542533A (en) * | 2016-10-25 | 2017-03-29 | 成都新柯力化工科技有限公司 | A kind of preparation method of inexpensive aqueouss aerosil |
| CN107857273A (en) * | 2017-12-01 | 2018-03-30 | 武汉理工大学 | The device of automatic replacing solvent in a kind of hydrophobic silicon dioxide aerogel preparation process |
| CN110003527A (en) * | 2019-04-10 | 2019-07-12 | 合肥华凌股份有限公司 | Modified aerogels, hard polyurethane foams and preparation method thereof, electric appliance |
| TWI793839B (en) * | 2021-11-01 | 2023-02-21 | 台灣氣凝膠科技材料開發股份有限公司 | Low-k dielectric aerogel powder and low-k dielectric aerogel suspension, composite film and preparation method therefor |
| TWI833358B (en) * | 2022-09-19 | 2024-02-21 | 台灣氣凝膠科技材料開發股份有限公司 | Low-dielectric and low-thermal-conductivity aerogel composite and preparation method thereof |
-
2007
- 2007-03-29 CN CNA2007100890785A patent/CN101274762A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101837982A (en) * | 2010-03-19 | 2010-09-22 | 福建师范大学 | Method for preparing silicon dioxide aerogel powder |
| CN102199378A (en) * | 2011-03-21 | 2011-09-28 | 冷水江三A化工有限责任公司 | Preparation method for silica aerogel flatting agent |
| CN106542533A (en) * | 2016-10-25 | 2017-03-29 | 成都新柯力化工科技有限公司 | A kind of preparation method of inexpensive aqueouss aerosil |
| CN107857273A (en) * | 2017-12-01 | 2018-03-30 | 武汉理工大学 | The device of automatic replacing solvent in a kind of hydrophobic silicon dioxide aerogel preparation process |
| CN110003527A (en) * | 2019-04-10 | 2019-07-12 | 合肥华凌股份有限公司 | Modified aerogels, hard polyurethane foams and preparation method thereof, electric appliance |
| TWI793839B (en) * | 2021-11-01 | 2023-02-21 | 台灣氣凝膠科技材料開發股份有限公司 | Low-k dielectric aerogel powder and low-k dielectric aerogel suspension, composite film and preparation method therefor |
| TWI833358B (en) * | 2022-09-19 | 2024-02-21 | 台灣氣凝膠科技材料開發股份有限公司 | Low-dielectric and low-thermal-conductivity aerogel composite and preparation method thereof |
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Open date: 20081001 |