Hollow glass bead foaming agent of borosilicate glass system

Abstract

The invention discloses a borosilicate glass system hollow glass bead foaming agent. The foaming agent is a mixture of magnesium sulfate, yttrium sulfate and calcium sulfate; the preparation process of the foaming agent for the hollow glass beads comprises the following steps: step 1, mixing a glass raw material with the foaming agent to obtain a batch mixture, and melting to obtain molten glass; 2, quickly pouring the glass liquid into water, cooling, drying, crushing and grading to obtain glass powder; and 3, carrying out high-temperature spheroidizing treatment on the glass powder, collecting by a collector, and sorting by a floating method to obtain the hollow glass beads. The preparation method has the beneficial effects that by optimizing the proportion and the dosage of the foaming agent, segmented slow-release foaming is realized in the preparation of the borosilicate glass hollow microspheres, the yield is remarkably improved, meanwhile, the density and the isostatic pressing strength of the microspheres are accurately regulated and controlled, and the key problems that gas release of a traditional foaming agent is uncontrollable and the yield is low are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hollow glass microsphere preparation, and particularly relates to a foaming agent for borosilicate glass system hollow glass microspheres. BACKGROUND

[0002] The industrialized production of hollow glass microspheres originated from the 3M Company in the United States in the 1950s, and by the 1970s, it has been widely used in many fields as a new type of filling material. However, for some high-performance hollow glass microspheres, there are still problems of great difficulty in obtaining and high cost.

[0003] At present, high-performance hollow glass microspheres all use borosilicate glass system worldwide. This glass is formed by the mutual connection of silicon-oxygen tetrahedron and boron-oxygen tetrahedron to form a network structure, which has high elastic modulus and high chemical stability, so the prepared microspheres have more excellent compression resistance and chemical stability.

[0004] In terms of preparation process, the preparation process of the glass powder method is mainly to design the glass formula first, and then melt the glass. In the melting process, a foaming agent is introduced to initiate the subsequent foaming process. Next, the melted glass is crushed to a specific particle size to form glass powder. Then, these glass powders are placed in a high-temperature environment for hollow foaming treatment, and finally hollow glass microspheres are obtained.

[0005] In terms of foaming agent selection, 3M Company is a representative abroad, and its patents US3365315, US4391646 and Russian patent R2059574, Japanese patent JP2006-193373A all use sodium sulfate (Na2SO4) as a foaming agent. However, the decomposition temperature of Na2SO4 is concentrated in 1400-1450℃, and the gas release speed is too fast, which makes it difficult to accurately control the foaming behavior in the preparation process of hollow glass microspheres, and easily reduces the yield of finished products and increases the cost due to the gas breaking through the microsphere ball wall. In addition, Na2SO4 is easy to form mirabilite water in the glass powder preparation process, which causes serious erosion to the refractory materials of the melting furnace.

[0006] In view of this problem, domestic patent CN102849947A proposes to use sodium antimonate (NaSb(OH)6) as a foaming agent. Its advantage lies in that it can release gas in stages to realize slow-release foaming, so as to accurately control the gas release amount by adjusting the amount and decomposition temperature of NaSb(OH)6, so that the performance of hollow glass microspheres is more controllable. Its reaction equation is as follows: ; However, from the reaction equation, it can be seen that the first stage decomposition temperature is too low, at this time the glass raw material has not been completely melted, and the glass state cannot be formed; and the third stage decomposition does not produce gas, and the foaming cannot be realized. The real effective foaming only occurs at 1427 DEG C in the second stage, but the decomposition product is oxygen. Because the solubility of oxygen in the borosilicate glass melt is low and it is extremely volatile, the re-foaming yield of the hollow glass microsphere in the subsequent spheroidization process is still low.

[0007] Therefore, in order to solve the above problems, the present application provides a borosilicate glass system hollow glass microsphere foaming agent. SUMMARY

[0008] The present application aims to overcome the defects of the prior art, and provides a borosilicate glass system hollow glass microsphere foaming agent.

[0009] The object of the present application can be achieved by the following technical solutions: A borosilicate glass system hollow glass microsphere foaming agent is a mixture of magnesium sulfate, yttrium sulfate and calcium sulfate; wherein the mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate is (2-4):(3-6):(2-4).

[0010] More preferably, the mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate is (2-4):4:(2-4).

[0011] The above foaming agent can be used for the preparation of hollow glass microspheres, including the following processes: Step 1: mixing glass raw materials and foaming agent to obtain a batch, melting to obtain a glass liquid; Step 2: rapidly pouring the glass liquid into water to cool, drying, crushing and grading to obtain a glass powder; Step 3: high-temperature spheroidization treatment of the glass powder, collecting by a collector, and sorting by a floating method to obtain hollow glass microspheres.

[0012] In the scheme, magnesium sulfate, yttrium sulfate and calcium sulfate in the foaming agent are the core components of the foaming agent, which can realize segmented and slow-release foaming at 1168 DEG C-1273 DEG C-1473 DEG C, and the main mechanism is as follows: The sulfate is selected as the foaming agent, mainly because the borosilicate glass has excellent inclusion capacity for sulfate. In the molten state, part of the sulfate foaming agent is dissolved in the glass melt in the form of SO2 gas; another part reacts with SiO2 and enters the network structure of the borosilicate glass, and is released again in the subsequent high-temperature hollow spheroidization process, thereby realizing the hollowing of the glass powder.

[0013] The gas dissolved in the glass melt can play a role of clarification and homogenization in the glass melting stage, which helps to improve the quality of the glass; and the sulfate remaining in the glass network structure can be released slowly in the high-temperature stage of the subsequent spheroidization process, so as to avoid the problem that the microsphere ball wall is broken due to the concentrated release of the gas, thereby being more conducive to the realization of hollow spheroidization and the improvement of the yield of the hollow glass microspheres.

[0014] More preferably, the foaming agent is added in an amount of 0.5%-3% of the total amount of the batch.

[0015] More preferably, the density of the hollow glass microspheres is 0.12g / cm 3 -0.6g / cm 3 .

[0016] Compared with the prior art, the present application has the following advantages: (1) In the prior art, the decomposition temperature of sodium sulfate as a foaming agent is concentrated in 1400-1450℃, and the gas release speed is too fast to be accurately controlled, which easily breaks the microsphere ball wall and reduces the yield; in the present application, the mixture of magnesium sulfate, yttrium sulfate and calcium sulfate is used to realize the segmented and slow release foaming at three temperature stages of 1168℃, 1273℃ and 1473℃, the gas release is more uniform and controllable, the problem that the microsphere ball wall is broken is effectively avoided, and the yield is improved.

[0017] (2) In the scheme, the foaming system has excellent compatibility with borosilicate glass. The gas produced by the decomposition of the sulfate is partially dissolved in the glass melt, which plays a role of clarification and homogenization, and improves the overall quality of the glass; another part is retained in the glass network in the form of chemical bonding, which is gradually released in the subsequent spheroidization process, and ensures the uniform formation of the hollow structure. This dual action mechanism not only optimizes the foaming effect, but also enhances the structural stability of the microspheres.

[0018] (3) In the prior art, sodium sulfate foaming agent is easy to form mirabilite water, which causes serious erosion to the refractory material of the melting furnace, and the effective foaming temperature range of sodium antimonate foaming agent is relatively narrow, and oxygen is generated, which is not conducive to the stable formation of the microspheres. In contrast, the composite foaming agent of the present application has no corrosive by-products, and can accurately match the melting and foaming needs of borosilicate glass, which significantly improves the reliability and economy of the process. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] Example 1: The preparation process of the hollow glass microsphere is as follows: The mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate in the foaming agent is 4:4:2. The glass raw material comprises the following components: 62% SiO2, 11.5% Na2O, 9% CaO, 10% B2O3, 1% Li2O, 2% ZnO, and 4.5% Al2O3 in terms of the mass percentage of oxides. The actual raw materials are weighed according to the above glass raw material oxide percentage, specifically as follows: 62.06 kg of quartz sand, 19.65 kg of sodium carbonate, 16.05 kg of calcium carbonate, 17.71 kg of boric acid, 2.15 kg of lithium carbonate, 2.02 kg of zinc oxide, and 4.55 kg of aluminum oxide. Step 1: Mix the glass raw material and the foaming agent to obtain a batch; then melt at 1460℃ for 5h to obtain a glass liquid; the foaming agent accounts for 2.5% of the total amount of the batch. Step 2: Pour the glass liquid into water quickly to cool it down, and then dry, crush and classify it to obtain a glass powder (the particle size of the granular powder is D10=1.76μm, D50=6.60μm, D90=11.60μm, and the maximum measured particle size is not more than 13.31μm); Step 3: The glass powder is fed into a spheroidizing furnace at a speed of 8kg / h, and the spheroidizing temperature is controlled at 1480℃. The hollow-spheroidized glass powder is collected by a collector, and then the hollow glass microspheres are obtained by high-temperature spheroidizing treatment and separation by the floating method. The density of the hollow glass microspheres is 0.159g / cm 3 , the volume crushing rate is 20% when the isostatic strength of the hollow microspheres is 6.2MPa, and the yield is 95%.

[0021] Example 2: The preparation process of the hollow glass microsphere is as follows: The mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate in the foaming agent is 2:4:4. The glass raw material comprises the following components: 68% SiO2, 7.5% Na2O, 9% CaO, 10% B2O3, 2% Li2O, 1.5% ZnO, and 3% Al2O3 in terms of the mass percentage of oxides. The actual raw materials are weighed according to the above glass raw material oxide percentage, specifically as follows: 68.07 kg of quartz sand, 12.81 kg of sodium carbonate, 16.05 kg of calcium carbonate, 15.94 kg of boric acid, 4.30 kg of lithium carbonate, 1.52 kg of zinc oxide, and 3.03 kg of aluminum oxide. Step 1: Mix the actual raw materials and the foaming agent to obtain a batch; then melt at 1540℃ for 5h to obtain a glass liquid; the foaming agent accounts for 1.5% of the total amount of the batch. Step 2: The glass liquid is quickly poured into water for cooling, and after drying, crushing and grading are performed to obtain glass powder (particle powder particle size D10 = 2.38 μm, D50 = 8.67 μm, D90 = 15.18 μm, and the maximum measured particle size is not more than 18.14 μm); Step 3: The glass powder is sent into a spheroidizing furnace at a speed of 8 kg / h, and the spheroidizing temperature is controlled at 1580℃. The hollow-spheroidized glass powder is collected by a collector, and the hollow glass microsphere glass powder is sorted out by a floating method for high-temperature spheroidizing treatment. After being collected by the collector, the hollow glass microspheres are obtained by the floating method, and the density is 0.383 g / cm 3 When the isostatic compressive strength of the hollow microspheres is 52.7 MPa, the volume crushing rate is 20%, and the yield is 90%.

[0022] Example Three: The preparation process of the hollow glass microspheres is as follows: The mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate in the foaming agent is 3:4:3. The glass raw material includes the following components: 70% SiO2, 6% Na2O, 9% CaO, 12% B2O3, 0.5% Li2O, 1% ZnO, and 1.5% Al2O3 in terms of oxide mass percentage. The actual raw materials are weighed according to the oxide percentage of the above glass raw material, and the specific weights are as follows: 70.07 kg of quartz sand, 10.25 kg of sodium carbonate, 16.05 kg of calcium carbonate, 21.26 kg of boric acid, 1.08 kg of lithium carbonate, 1.01 kg of zinc oxide, and 1.52 kg of aluminum oxide. Step 1: The actual raw materials and the foaming agent are mixed to obtain a mixture; then the mixture is melted at 1510℃ for 5h to obtain a glass liquid; the foaming agent accounts for 1.2% of the total amount of the mixture; Step 2: The glass liquid is quickly poured into water for cooling, and after drying, crushing and grading are performed to obtain glass powder (particle powder particle size D10 = 2.55 μm, D50 = 9.52 μm, D90 = 16.73 μm, and the maximum measured particle size is not more than 19.20 μm); Step 3: The glass powder is sent into a spheroidizing furnace at a speed of 8 kg / h, and the spheroidizing temperature is controlled at 1520℃. The hollow-spheroidized glass powder is collected by a collector, and the hollow glass microsphere glass powder is sorted out by a floating method for high-temperature spheroidizing treatment. After being collected by the collector, the hollow glass microspheres are obtained by the floating method, and the density is 0.454 g / cm 3 When the isostatic compressive strength of the hollow microspheres is 67.5 MPa, the volume crushing rate is 20%, and the yield is 88%.

[0023] In the description, references to "one embodiment," "an example," "certain examples" etc. mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of an item in various examples or embodiments is not necessarily indicative of a frequency of occurrence in the various examples or embodiments. Moreover, descriptions of well-known methods associated are omitted so as not to obscure the disclosure.

[0024] The foregoing merely illustrates the principles of the application. Various modifications and adaptations will occur to those skilled in the art after consideration of the preceding description. All such modifications and adaptations employing the principles of the application are intended to be within the scope of the claims.

Claims

1. A foaming agent for hollow glass microspheres in a borosilicate glass system, characterized in that: The foaming agent is a mixture of magnesium sulfate, yttrium sulfate and calcium sulfate; wherein the mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate is (2-4):(3-6):(2-4).

2. The borosilicate glass system hollow glass microsphere foaming agent according to claim 1, characterized in that: The mass ratio of magnesium sulfate, yttrium sulfate and calcium sulfate is (2-4):4:(2-4).

3. The application of the borosilicate glass system hollow glass microsphere foaming agent according to any one of claims 1-2, characterized in that: Process for preparing hollow glass microspheres.

4. The application of the borosilicate glass system hollow glass microsphere foaming agent according to claim 3, characterized in that: The preparation process of hollow glass microspheres includes the following steps: Step 1: Mix the glass raw materials and foaming agent to obtain the batch material, and then melt it to obtain molten glass; Step 2: Quickly pour the molten glass into water to cool it, dry it, and then crush and classify it to obtain glass powder; Step 3: The glass powder is subjected to high-temperature spheroidization treatment, collected by a collector, and then sorted by flotation method to obtain hollow glass microspheres.

5. The application of the borosilicate glass system hollow glass microsphere foaming agent according to claim 4, characterized in that: The amount of foaming agent added is 0.5%-3% of the total amount of the batch material.

6. The application of the borosilicate glass system hollow glass microsphere foaming agent according to claim 4, characterized in that: The density of the hollow glass microspheres is 0.12 g / cm³. 3 -0.6g / cm 3 .

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