阅读说明：本技术 高固含量硅溶胶及其制备方法和应用 (High solid content silica sol, preparation method and application thereof ) 是由 张雨葳 刘俊君 佘平江 吴广力 于 2021-10-18 设计创作，主要内容包括：本发明公开一种高固含量硅溶胶及其制备方法和应用,该制备方法包括S1、将一定量的硅溶胶加入三口烧瓶中,在室温状态下搅拌后得到A液；S2、将稀氨水在搅拌的状态下滴加进入A液中,边滴加边测量溶液pH值,直到调节A液pH至8.1-8.4,得到B液；S3、在室温搅拌状态下加入与硅溶胶质量比为1：1的硅烷偶联剂,搅拌得到C液；S4、将乙酸在磁力搅拌的状态下滴加进入C液中,边滴加边测量溶液pH值,直到调节C液pH至3.6-3.9,得到D液；S5、将D液在室温下静置反应8小时,得到E液；S6、将E液按照设计质量比加入到硅溶胶中,在室温状态下混合均匀,得到高固含量硅溶胶。经过该方法所得的硅溶胶固含量较高,粒度理论上分布均匀且制备工艺简单。(The invention discloses a high solid content silica sol and a preparation method and application thereof, wherein the preparation method comprises the steps of S1, adding a certain amount of silica sol into a three-neck flask, and stirring at room temperature to obtain solution A; s2, dropwise adding dilute ammonia water into the solution A while stirring, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.1-8.4, and obtaining solution B; s3, adding the mixture in a mass ratio of 1:1, stirring to obtain a solution C; s4, dropwise adding acetic acid into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding the acetic acid until the pH value of the solution C is adjusted to 3.6-3.9, and obtaining solution D; s5, standing the solution D at room temperature for 8 hours to obtain solution E; and S6, adding the solution E into the silica sol according to the designed mass ratio, and uniformly mixing at room temperature to obtain the high-solid-content silica sol. The silica sol obtained by the method has higher solid content, uniform particle size distribution in theory and simple preparation process.)

1. A preparation method of high solid content silica sol is characterized by comprising the following steps:

s1, adding a certain amount of silica sol into a flask, and magnetically stirring for a period of time at room temperature to obtain solution A;

s2, dropwise adding dilute ammonia water into the solution A under the magnetic stirring state, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.1-8.4, and obtaining solution B;

s3, adding a silane coupling agent with the mass ratio of 1:1 to the silica sol under the magnetic stirring state at room temperature, and stirring for a period of time to obtain solution C;

s4, dropwise adding acetic acid into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding the acetic acid until the pH value of the solution C is adjusted to 3.6-3.9, and obtaining solution D;

s5, standing the solution D at room temperature for reaction for a period of time to obtain solution E;

and S6, adding the solution E into the silica sol according to the designed mass ratio, and uniformly mixing at room temperature to obtain the high-solid-content silica sol.

2. The method according to claim 1, wherein the silica sol is an acidic silica sol.

3. The method for preparing a high-solid content silica sol according to claim 1, wherein the stirring time in each of the steps S1 and S3 is 15 min.

4. The method for preparing high-solid content silica sol according to claim 1, wherein the mass percentage of the dilute ammonia water in the step S2 is 0.05-0.3%.

5. The method for preparing a high-solid content silica sol according to claim 1, wherein the silane coupling agent in step S3 is methyltrimethoxysilane.

6. The method according to claim 1, wherein the acetic acid content in step S4 is 2-4% by mass.

7. The method according to claim 1, wherein the solution D in step S5 is left to react at room temperature for 8 hours.

8. The method for preparing a high-solid content silica sol according to claim 1, wherein the solution E in the step S6 is added to the silica sol in a mass ratio of (4-4.5) to (21-22).

9. A high-solid-content silica sol, which is characterized by being prepared by the preparation method of any one of claims 1 to 8.

10. Use of a high solids silica sol according to claim 9 in a ceramic coating, the method comprising:

taking an untreated ceramic flat plate blank, immersing the blank in high-solid-content silica sol, controlling the gel temperature at 60-80 ℃, and immersing for 6-8 h;

and (3) putting the ceramic flat plate into a muffle furnace, heating to 120 +/-10 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, heating to 1000 +/-20 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, cooling to room temperature along with the furnace, taking out, polishing and trimming corner positions according to product sizes, and obtaining the quartz composite ceramic flat plate with smooth and flat surface and high solid content.

Technical Field

The invention relates to the technical field of inorganic nano materials, in particular to high-solid-content silica sol and a preparation method and application thereof.

Background

The silica sol is a material system with excellent performance, in which silica nanoparticles are uniformly dispersed in water or an organic solvent, and has the characteristics of large specific surface area, high dispersity, high surface activity and the like due to a network structure formed by countless micelles, so that the silica sol is widely applied to the fields of coating industry, catalytic industry and the like.

However, the currently widely popular method for preparing silica sol has the disadvantages of low solid content of silica, poor uniformity of particle size, poor stability, difficulty in long-term storage and the like, and thus has a great obstacle in the practical application process.

Based on the situation, the invention provides the high-solid-content silica sol, and the preparation method and the application thereof, and the problems can be effectively solved.

Disclosure of Invention

In view of the disadvantages of the prior art, a first object of the present invention is to provide a high solid content silica sol. Has the advantages of high solid content of silicon dioxide, good granularity uniformity, strong stability, long storage time and the like.

The second purpose of the invention is to provide a preparation method of the high-solid-content silica sol. The silica sol obtained by the method has higher solid content, uniform particle size distribution in theory and simple preparation process.

The second purpose of the invention is to provide the application of the high-solid-content silica sol. The ceramic flat plate with higher density and better apparent mass can be obtained by placing the ceramic flat plate in the glue solution for compounding.

In order to solve the technical problems, the invention is realized by the following technical scheme:

in one aspect, the invention provides a preparation method of high solid content silica sol, comprising the following steps:

s1, adding a certain amount of silica sol into a flask, and magnetically stirring for a period of time at room temperature to obtain solution A;

s2, dropwise adding dilute ammonia water into the solution A under the magnetic stirring state, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.1-8.4, and obtaining solution B;

s3, adding a silane coupling agent with the mass ratio of 1:1 to the silica sol under the magnetic stirring state at room temperature, and stirring for a period of time to obtain solution C;

s4, dropwise adding acetic acid into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding the acetic acid until the pH value of the solution C is adjusted to 3.6-3.9, and obtaining solution D;

s5, standing the solution D at room temperature for reaction for a period of time to obtain solution E;

and S6, adding the solution E into the silica sol according to the designed mass ratio, and uniformly mixing at room temperature to obtain the high-solid-content silica sol.

Preferably, the silica sol is an acidic silica sol.

Preferably, the stirring time periods in the steps S1 and S3 are both 15 min.

Preferably, the mass percentage of the dilute ammonia water in the step S2 is 0.05-0.3%.

Preferably, the silane coupling agent in step S3 is methyltrimethoxysilane.

Preferably, the solution D in step S5 is left to stand at room temperature for 8 hours.

Preferably, the mass percentage of the acetic acid in the step S4 is 2-4%.

Preferably, the solution E in the step S6 is added into the silica sol according to the mass ratio of (4-4.5): 21-22.

On the other hand, the high-solid-content silica sol is prepared by the preparation method in the scheme.

In yet another aspect, there is provided a method of using a high solids silica sol in a ceramic coating, the method comprising:

taking an untreated ceramic flat plate blank, immersing the blank in high-solid-content silica sol, controlling the gel temperature at 60-80 ℃, and immersing for 6-8 h;

and (3) putting the ceramic flat plate into a muffle furnace, heating to 120 +/-10 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, heating to 1000 +/-20 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, cooling to room temperature along with the furnace, taking out, polishing and trimming corner positions according to product sizes, and obtaining the quartz composite ceramic flat plate with smooth and flat surface and high solid content.

Siloxane monomers and nano SiO₂The reaction that takes place can be divided into four stages,

the first stage is as follows: the siloxane undergoes a hydrolysis reaction process under the action of an acid catalyst, and a plurality of siloxane monomers in a reaction system begin to undergo hydrolysis reaction gradually to produce silanol;

and a second stage: the silanol generated by the hydrolysis of the siloxane monomer generates a random polycondensation reaction through the dehydration of silicon hydroxyl to generate chain-like substance oligomers and particles with small molecular weight;

and a third stage: chain oligomer and particle with small molecular weight and nano SiO in silica sol₂The particles are combined together through the random polycondensation reaction of the silicon hydroxyl on the surface;

a fourth stage: the system continues to generate chain oligomers with larger molecular weight and more nano SiO₂The particles are subjected to polycondensation reaction and finally polymerized to form a three-dimensional network structure.

During the course of the reaction, the siloxane monomers undergo a complex hydrolysis and polycondensation reaction. The reaction speed of siloxane compounds can be influenced by factors such as the type and content of siloxane, the hydrolysis pH value, the type of catalyst, the hydrolysis reaction time and the like, and the structure and performance of the prepared high-solid-content silica sol can be finally influenced.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the modification of the silica sol is to modify the silica sol by a silane coupling agent (to link inorganic Si and organic components), so that the agglomeration of silica sol particles is effectively prevented. The action mechanism is as follows: part of reactive groups of the silane coupling agent react with silicon hydroxyl on the surface of the silica sol particles to form covalent bonds (organic functional groups are introduced), so that the functional groups on the surface of colloidal particles are not single any more, and the solid content of the silica sol is improved.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the following description of the preferred embodiments of the present invention is provided in connection with specific examples, which should not be construed as limiting the present patent, but merely as exemplifications.

The test methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials, unless otherwise indicated, are conventionally obtained commercially or prepared by conventional methods.

The invention provides a preparation method of high-solid-content silica sol, which comprises the following steps:

s1, adding a certain amount of silica sol into a flask, and magnetically stirring for a period of time at room temperature to obtain solution A.

Preferably, the flask is a three-neck flask, the silica sol is acidic silica sol, and the stirring time is 15 min.

And S2, dropwise adding dilute ammonia water into the solution A under the magnetic stirring state, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.1-8.4, and obtaining solution B.

Preferably, the mass percentage content of the dilute ammonia water is 0.05-0.3%. The solution C obtained by adding diluted ammonia water is alkaline, and the alkaline environment can be used as a buffer, so that the agglomeration phenomenon caused by a large amount of siloxane hydrolysis due to peracid in the subsequent process of adding acetic acid is avoided.

And S3, adding a silane coupling agent with the mass ratio of 1:1 to the silica sol under the magnetic stirring state at room temperature, and stirring for a period of time to obtain a solution C.

Preferably, the silane coupling agent is methyl trimethoxy silane (MTMS) and the stirring time is 15 min.

And S4, dropwise adding acetic acid into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding the acetic acid until the pH value of the solution C is adjusted to 3.6-3.9, and obtaining solution D.

Preferably, the mass percentage of the acetic acid is 2-4%

And S5, standing the solution D at room temperature for reaction for a period of time to obtain solution E.

Preferably, the solution D is kept still for reaction for 8 hours at room temperature.

And S6, adding the solution E into the silica sol according to the designed mass ratio, and uniformly mixing at room temperature to obtain the high-solid-content silica sol.

Preferably, the solution E is added into the silica sol according to the mass ratio of (4-4.5) to (21-22).

In addition, the invention also provides the high-solid-content silica sol prepared by the method, which has the advantages of high solid content of silicon dioxide, good granularity uniformity, strong stability, long storage time and the like.

The high-solid-content silica sol can be applied to ceramic coatings, and the application method comprises the following steps:

taking an untreated ceramic flat plate blank, immersing the blank in high-solid-content silica sol, controlling the gel temperature at 60-80 ℃, and immersing for 6-8 h;

and (3) putting the ceramic flat plate into a muffle furnace, heating to 120 +/-10 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, heating to 1000 +/-20 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, cooling to room temperature along with the furnace, taking out, polishing and trimming corner positions according to product sizes, and obtaining the quartz composite ceramic flat plate with smooth and flat surface and high solid content.

The silica sol and the silane coupling agent used in the following examples are commercially available products.

Example 1:

1) preparing raw materials: methyltrimethoxysilane (MTMS), silica sol HP4010A, dilute ammonia, acetic acid.

2) Adding 2kg of silica sol HP4010A into a three-neck flask, and magnetically stirring for 15min at room temperature to obtain solution A;

3) dropwise adding 0.1 mass percent of dilute ammonia water into the solution A under the state of magnetic stirring, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.1, and obtaining solution B;

4) adding 2kg of methyltrimethoxysilane (MTMS) under magnetic stirring at room temperature, and stirring for 15min to obtain solution C;

5) dropwise adding acetic acid with the mass percentage of 2% into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding until the pH value of the solution C is adjusted to 3.6, and obtaining a solution D;

6) standing the solution D at room temperature for 8 hours to obtain solution E;

7) and adding the solution E into 21kg of HP4010A high-purity silica sol, and uniformly mixing at room temperature to obtain 25kg of silica sol with high solid content.

The high solid content silica sol prepared by the method is applied to ceramic paint, and the specific steps are as follows:

immersing a ceramic flat blank with the thickness of 100 multiplied by 30mm in silica sol with high solid content, controlling the glue temperature at 80 ℃ and immersing for 8 hours;

and (3) putting the ceramic flat plate into a muffle furnace, heating to 120 ℃ at a speed of 3 ℃/min, preserving heat for 120min +/-10 min, heating to 1000 ℃ +/-20 ℃ at a speed of 3 ℃/min, preserving heat for 120min +/-10 min, cooling to room temperature along with the furnace, taking out, polishing and finishing the ceramic flat plate after dipping and compounding to obtain the quartz composite ceramic flat plate with high solid content. The measured density of the ceramic flat plate was 1.86g/cm³The apparent mass is better, and the conditions of pits, slag falling and the like are avoided. The properties of the test specimens were tested and the results are shown in Table 1.

Table 1 results of performance testing

Example 2:

1) preparing raw materials: methyltrimethoxysilane (MTMS), silica sol HP4010A, dilute ammonia, acetic acid.

2) Adding 4kg of silica sol HP4010A into a three-neck flask, and magnetically stirring for 15min at room temperature to obtain solution A;

3) dropwise adding 0.2 mass percent of dilute ammonia water into the solution A under the state of magnetic stirring, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.2, and obtaining solution B;

4) adding 4kg of methyltrimethoxysilane (MTMS) under magnetic stirring at room temperature, and stirring for 15min to obtain solution C;

5) dropwise adding acetic acid with the mass percentage of 3% into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding until the pH value of the solution C is adjusted to 3.7, and obtaining a solution D;

6) standing the solution D at room temperature for 8 hours to obtain solution E;

7) and adding the solution E into 42kg of HP4010A high-purity silica sol, and uniformly mixing at room temperature to obtain 50kg of silica sol with high solid content.

The high solid content silica sol prepared by the method is applied to ceramic paint, and the specific steps are as follows:

A100X 30mm ceramic plate blank is immersed in high-solid content silica sol, the gel temperature is controlled at 70 ℃, and the ceramic plate blank is immersed for 7 hours.

And (3) putting the ceramic flat plate into a muffle furnace, heating to 120 +/-10 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, heating to 1000 +/-20 ℃ at a speed of 3 ℃/min, preserving heat for 120 +/-10 min, cooling to room temperature along with the furnace, taking out, polishing and trimming corner positions according to product sizes, and obtaining the quartz composite ceramic flat plate with high solid content. The measured density of the ceramic flat plate was 1.84g/cm³The apparent mass is better, and the conditions of pits, slag falling and the like are avoided. The properties of the test specimens were tested and the results are shown in Table 2.

Table 2 results of performance testing

Example 3:

1) preparing raw materials: methyltrimethoxysilane (MTMS), silica sol HP4010A, dilute ammonia, acetic acid;

2) adding 2kg of silica sol HP4010A into a three-neck flask, and magnetically stirring for 15min at room temperature to obtain solution A;

3) dropwise adding 0.3% by mass of dilute ammonia water into the solution A under the condition of magnetic stirring, measuring the pH value of the solution while dropwise adding until the pH value of the solution A is adjusted to 8.4, and obtaining solution B;

4) adding 2kg of methyltrimethoxysilane (MTMS) under magnetic stirring at room temperature, and stirring for 15min to obtain solution C;

5) dropwise adding acetic acid with the mass percentage of 4% into the solution C under the magnetic stirring state, measuring the pH value of the solution while dropwise adding until the pH value of the solution C is adjusted to 3.9, and obtaining a solution D;

6) standing the solution D at room temperature for 8 hours to obtain solution E;

7) and adding the solution E into 21kg of HP4010A high-purity silica sol, and uniformly mixing at room temperature to obtain 25kg of silica sol with high solid content.

The high solid content silica sol prepared by the method is applied to ceramic paint, and the specific steps are as follows:

A100X 30mm ceramic flat plate is immersed in the high-solid content silica sol, the gel temperature is controlled at 60 ℃, and the ceramic flat plate is immersed for 6 hours.

And (3) putting the ceramic flat plate into a muffle furnace, heating to 120 ℃ at a speed of 3 ℃/min, preserving heat for 120min +/-10 min, heating to 1000 ℃ +/-20 ℃ at a speed of 3 ℃/min, preserving heat for 120min +/-10 min, cooling to room temperature along with the furnace, taking out, polishing and finishing the ceramic flat plate after dipping and compounding to obtain the quartz composite ceramic flat plate with high solid content. The measured density of the ceramic flat plate was 1.85g/cm³The apparent mass is better, and the conditions of pits, slag falling and the like are avoided. The properties of the test specimens were tested and the results are shown in Table 3.

Table 3 results of performance testing

Serial number	Item	Unit of	Test results
				1	Density of	g/cm3	1.85
2	Bending strength	MPa	66
				3	Tensile strength	MPa	48
4	Coefficient of linear expansion	×10-6/℃	0.24
				5	Coefficient of thermal conductivity	W/m·k	0.51
6	Dielectric constant (15 to 17GHz)	/	3.3
				7	Loss tangent (15 to 17GHz)	/	0.0004

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.