CN107857498A - A kind of silicon ash of silane ether surfactant modification and its preparation method and application - Google Patents

Abstract

The present invention relates to silica fume modified by silane ether surfactant and its preparation method and application. The molecular structural formula of the silane ether surfactant is as follows: Wherein, both a and b are non-zero integers, and n is an integer between 10 and 20. The provided silica fume modified with silane ether surfactants has good dispersibility, and when added to concrete as an admixture, the obtained concrete has high strength, good fluidity, and good stability, so it can be used in the field of 3D printing.

Description

A kind of silica fume modified by silane ether surfactant and its preparation method and application

technical field

The invention belongs to the technical field of cement concrete admixtures, and relates to silica fume modified with silane ether surfactants, a preparation method and application thereof.

Background technique

Silica fume is the silicon oxide compound powder collected from the dust when the ferrosilicon alloy factory uses high-purity quartz to smelt metallic silicon or ferrosilicon alloy, and its main component is silicon dioxide. During its formation, it is affected by the surface tension, and the amorphous spherical particles of the non-crystalline phase are obtained, and the surface is relatively smooth. When silica fume is mixed with other materials, the tiny spheroids can play a role of lubrication, realize the ball effect, improve the fluidity between water and aggregates, cementitious materials (such as cement and gypsum) particles, etc., and reduce water. , Strengthening, increasing body density, and improving the flexural and compressive strength, thereby greatly improving the service life of product materials and acid and alkali corrosion resistance, and can reduce the amount of cementitious materials added. Due to the above advantages, silica fume has been widely used in industries such as refractory materials, ceramics, rubber, cement, concrete, grouting materials, external wall insulation, mortar and road bridges. In 2012, the thirteenth member congress of China Building Materials Federation Concrete Admixtures Branch disclosed the characteristics of silica fume and its special effects in cement-based materials: silica fume can reduce viscosity, increase yield value, and improve the stability of concrete mixtures , Reduce the sensitivity to raw material variation and batching errors, and at the same time improve cohesion, reduce bleeding, help pumps, improve impermeability, strength and durability, and low dosage (below 5%) Sometimes there is a physical reduction effect. However, because the average particle size of untreated silica fume is in the micron level, the specific surface area is very large, and it is easy to stick and agglomerate, which makes the concrete too sticky and difficult to construct. Therefore, it is of great significance for the promotion of silica fume to study functionalized silica fume that has good dispersion and can be added to concrete to make the resulting concrete meet the performance of industrial production.

Contents of the invention

The technical problem to be solved by the present invention is to provide a kind of silica fume modified by silane ether surfactant and its preparation method and application in view of the above-mentioned deficiencies in the prior art. The silica fume modified by silane ether surfactant provided The ash has good dispersibility, and as an inorganic admixture added to concrete, the resulting concrete has high strength, good fluidity, and good stability, so it can be used in the field of 3D printing.

In order to solve the problems of the technologies described above, the technical solution provided by the invention is:

A kind of silica fume modified by silane ether surfactant is provided, and the molecular structural formula of the silane ether surfactant is as follows:

Wherein a is an integer between 18 and 8, b is an integer between 12 and 40, and n is an integer between 10 and 20.

The present invention also provides a preparation method of silica fume modified by the above-mentioned silane ether surfactant, the specific steps are as follows:

1) Dissolving prenol polyoxyethylene ether in water at 25-40°C, adjusting the pH value to 5-6, and stirring evenly to obtain a prenol polyoxyethylene ether solution;

2) Dissolve vinyltriethoxysilane in water at 25-40°C, adjust the pH value to 5-6, and stir evenly to obtain a vinyltriethoxysilane solution;

3) Add an initiator to the prenol polyoxyethylene ether solution obtained in step 1), add dropwise the vinyltriethoxysilane solution obtained in step 2) to the reaction system, and simultaneously add a mixture of ascorbic acid and a chain transfer agent dropwise. Solution, add dropwise at 25-40°C for 3-4 hours to obtain a mixed solution containing silane ether surfactants;

4) Dilute the mixed solution containing silane ether surfactant obtained in step 3) with absolute ethanol, adjust the pH value to 5-6, then mix it with the silica fume treated with surface hydroxylation, and ultrasonically disperse at 25-45°C 0.5 to 1 hour, then stirred and reacted for 6 to 12 hours, then centrifuged, washed, and dried to obtain silica fume modified with silane ether surfactants.

Preferably, the concentration of the isopentenol polyoxyethylene ether solution in step 1) is 1.5-3.5 mol/L.

Preferably, the concentration of the vinyltriethoxysilane solution in step 2) is 9-36 mol/L.

Preferably, the molar ratio of prenol polyoxyethylene ether to vinyltriethoxysilane in step 3) is 1:1-4.

Preferably, the initiator in step 3) is a hydrogen peroxide solution with a concentration of 25-28%.

According to the above scheme, the mass concentration of ascorbic acid in the mixed solution of ascorbic acid and chain transfer agent in step 3) is 0.5-1%, and the mass concentration of chain transfer agent is 1-2%.

According to the above scheme, the isopentenol polyoxyethylene ether described in step 3) is measured in 100 parts by weight, and the addition amount of other raw material components is as follows: 0.5 to 3 parts of initiator, 0.15 to 0.4 part of ascorbic acid, chain transfer agent 0.1 to 0.8 parts.

According to the above scheme, the chain transfer agent described in step 3) is one or both of mercaptopropionic acid or mercaptoacetic acid.

Preferably, in step 4), the mass volume ratio of the mixed solution containing silyl ether surfactants to absolute ethanol is 1 g: 100-200 mL. Treatment with absolute ethanol prevents gel formation.

Preferably, in step 4), the mass ratio of the mixed solution containing silane ether surfactants to the silica fume treated with surface hydroxylation is 0.3-1.0:100.

According to the above scheme, the preparation method of silica fume treated with surface hydroxylation in step 4) is as follows: at a temperature of 70-80° C. and a pH value of 6-8, ultrasonically disperse silica fume in a mixed solvent of ethanol and water to obtain , wherein the mass ratio of silica fume to the mixed solvent is 1:10-15; the volume ratio of ethanol to water in the mixed solvent is 1:2-4.

The present invention also provides concrete containing silica fume modified by the above-mentioned silane ether surfactant. When in use, the silane ether-containing surfactant surface-modified silica fume prepared by the present invention is added to cement concrete in different amounts according to different requirements, and then put into a concrete mixer and stirred according to the normal concrete mixing process.

And the application of the above-mentioned concrete in 3D printing.

The beneficial effects of the present invention are as follows: 1. The present invention uses prenol polyoxyethylene ether and vinyl triethoxysilane as raw materials to prepare silane ether surfactants, so that the synthesized comb-shaped block silane ether surface The active agent and the silica fume treated with surface hydroxylation are easier to bond together. In addition, the surface modified silica fume of the silane ether surfactant has a greater steric hindrance effect, which makes the synthesized silane ether surfactant surface modified silica fume have More excellent dispersion retention and stability improve the surface quality of silica fume, which in turn enables concrete to achieve higher flow properties and increases the strength of concrete products, thus being applied in more fields, such as 3D printing; 2 . The preparation process of the present invention is relatively simple, the reaction conditions are easy to control, and the requirements for production equipment are relatively low.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with examples.

The silica fume used in the embodiment of the present invention is provided by Elkem Company, with an average particle size of 0.1-0.3 μm and a bulk density of 200-450 Kg/m ³ .

Comparative example 1

Take 20g of silica fume and place it in a container, and add a mixed solvent of 40g of ethanol and 160g of water into the container, adjust the pH value to 6 with hydrochloric acid, heat to 70°C, and disperse ultrasonically for 30 minutes to obtain silica fume with surface hydroxylation treatment. Record it as blank P0.

Example 1

Prepare a kind of silica fume modified by silane ether surfactant, the specific steps are as follows:

(1) Dissolve 91.25g of prenol polyoxyethylene ether (molecular weight: 527, 0.17mol) in 50g of water at 40°C, adjust the pH value to 5, and stir evenly to obtain a prenol polyoxyethylene ether solution ;

(2) Dissolve 40g of vinyltriethoxysilane in 20g of water at 35°C, adjust the pH value to 5, and stir evenly to obtain a vinyltriethoxysilane solution;

(3) Add 2g hydrogen peroxide (mass concentration is 28%) in reaction vessel 1, add step (2) gained vinyltriethoxysilane solution and the aqueous solution of ascorbic acid and mercaptopropionic acid (wherein ascorbic acid 0.15g, mercaptopropionic acid 0.3g, water 30g), vinyltriethoxysilane solution was added dropwise for 3h, the aqueous solution of antioxidant and chain transfer agent was added dropwise for 3.5h, and the end of the dropwise addition obtained mixed solution;

(4) Weigh 20g of silica fume and place it in reaction vessel 2, and add a mixed solvent of 40g of ethanol and 160g of water into vessel 2, adjust the pH value to 6 with hydrochloric acid, heat to 70°C, and ultrasonically disperse for 30min to obtain a surface Hydroxylated silica fume;

(5) Dilute 0.1 g of the mixed solution containing silane ether surfactants obtained in step (3) with 20 mL of absolute ethanol to adjust the pH value to 6, and then mix it with the silica fume treated with surface hydroxylation obtained in step (4) , ultrasonically dispersed at 35°C for 0.5h, then stirred for 12h, and then the resulting suspension was centrifuged at 2000r/min, washed twice with a mixed solution of ethanol and water, and the obtained precipitate was dried in a drying oven at 60°C for 1 The silica fume modified with silane ether surfactant was obtained on the day, and the sample was recorded as P1.

The molecular structural formula of the silane ether surfactant prepared in the present embodiment is as follows:

Where a=17, b=21, n=10.

Example 2

A silica fume modified with a silane ether surfactant was prepared, the method was similar to that of Example 1, except that the amount of the silane ether surfactant added in step (6) was 0.2 g, and the obtained product was denoted as P2.

Example 3

The silica fume products prepared in Comparative Example 1 and Examples 1-2 were mixed into concrete, and the properties of the concrete were tested.

The ratio of concrete raw materials is: cement: fly ash: silica fume: water: sand: gravel: admixture = 1.0: 0.20: 0.12: 0.30: 1.75: 3.22: 0.02, and the dosage of silica fume is 1.8%. The concrete strength grade is C40. The slump, expansion and compressive strength of concrete are all carried out in accordance with the relevant operations in GB8076-2008 and GB50081-2002. The test results are shown in Table 1.

Table 1

From the test results of adsorption superplasticizers in Table 1, it can be seen that P1 and P2 are better than the blank example P0 in terms of water reducer adsorption, and at the same time, P1 and P2 are also better than the blank example in terms of concrete fluidity (the greater the degree of expansion, the greater the flow rate. The better the property), the concrete compressive strength prepared by mixing No. P1 and P2 is also significantly better than the prepared concrete of No. P0, that is, the silane ether surfactant modified silica fume produced by the present invention is better than that of ordinary surface Unmodified silica fume is better at improving concrete fluidity and increasing compressive strength, and can be used for 3D printing.

Each raw material enumerated in the present invention, and the upper and lower limits of each raw material of the present invention, the interval value, and the upper and lower limits of process parameters (such as temperature, time, etc.), the interval value can realize the present invention, do not enumerate one by one here Example.

Claims (10)

1. A kind of 1. silicon ash of silane ether surfactant modification, it is characterised in that the silane ether surfactant molecule Structural formula is as follows：

   Wherein a is the integer between 18~8, and b is the integer between 12~40, and n is the integer between 10~20.
2. A kind of 2. preparation method of the silicon ash of the silane ether surfactant modification described in claim 1, it is characterised in that tool Body step is as follows：

   1) at 25~40 DEG C, isoamyl alcohol polyoxyethylene ether is dissolved in water, regulation pH value is 5~6, is uniformly mixing to obtain isoamyl Enol polyoxyethylene ethereal solution；

   2) at 25~40 DEG C, VTES is dissolved in water, regulation pH value is 5~6, is uniformly mixing to obtain ethene Ethyl triethoxy silicane alkane solution；

   3) initiator is added into isoamyl alcohol polyoxyethylene ether solution obtained by step 1), step 2) institute is added dropwise into reaction system VTES solution is obtained, while the mixed solution of ascorbic acid and chain-transferring agent is added dropwise, is dripped at 25~40 DEG C Add reaction 3~4 hours, obtain the mixed liquor of silane-containing ether surfactant；

   4) mixed liquor of silane-containing ether surfactant obtained by step 3) being diluted with absolute ethyl alcohol, regulation pH value is 5~6, Then the silicon ash with surface hydroxylation processing mixes, and 0.5~1h of ultrasonic disperse at 25~45 DEG C, is stirred for 6~12h of reaction, The silicon ash of silane ether surfactant modification is centrifuged, washed, being dried to obtain again.
3. 3. preparation method according to claim 2, it is characterised in that step 1) the isoamyl alcohol polyoxyethylene ether solution Concentration be 1.5~3.5mol/L.
4. 4. preparation method according to claim 2, it is characterised in that step 2) the VTES solution Concentration be 9~36mol/L.
5. 5. preparation method according to claim 2, it is characterised in that isoamyl alcohol polyoxyethylene ether and ethene in step 3) The mol ratio of ethyl triethoxy silicane alkane is 1：1~4.
6. 6. preparation method according to claim 2, it is characterised in that the step 3) initiator is that concentration is 25~28% Hydrogen peroxide solution；The chain-transferring agent is one or both of mercaptopropionic acid or TGA.
7. 7. preparation method according to claim 2, it is characterised in that the mixing of step 4) silane-containing ether surfactant Liquid and the silicon ash mass ratio of surface hydroxylation processing are 0.3~1.0：100.
8. 8. preparation method according to claim 2, it is characterised in that the silicon ash system of step 4) the surface hydroxylation processing Preparation Method is as follows：In the case where temperature is 70~80 DEG C, pH value is 6~8, by silicon ash ultrasonic disperse in the in the mixed solvent of second alcohol and water Obtain, wherein the mass ratio of silicon ash and mixed solvent is 1：10~15；The volume ratio of in the mixed solvent second alcohol and water is 1：2~4.
9. A kind of 9. concrete of the silicon ash of the silane ether surfactant modification added with described in claim 1.
10. 10. application of the concrete according to claim 9 in terms of 3D printing.