Battery grid casting release agent and preparation process thereof

Abstract

The invention discloses a battery grid casting release agent and a preparation process thereof, and belongs to the technical field of release agents. The battery grid casting release agent is prepared from the following components in parts by weight: 0.8 to 1.2 parts of bone glue, 0.8 to 1.2 parts of polyvinyl alcohol, 1 to 2 parts of cork powder, 2 to 4 parts of diatomite, 0.2 to 0.6 part of modified nano silicon dioxide, 0.2 to 0.4 part of polymer and 70 to 75 parts of water. The nano silicon dioxide is modified, the diatomite is treated by adding the polymer, the modified nano silicon dioxide is high in dispersion degree, and the adhesive force between the release agent and a mold is increased due to the existence of sodium ions. The polymer and silanol groups on the surface of diatomite are subjected to physical adsorption through hydrogen-bond interaction, and polar groups in the polymer and polar groups on the surface of a mold are subjected to chemical bonding, so that the adhesive ability and the film-forming isolation ability of the release agent are enhanced, and the release agent has a good application prospect in industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of release agents, and in particular relates to a battery grid casting release agent and a preparation process thereof. Background Art

[0002] The grid is an important component of lead-acid batteries. Its function is to collect electrons and fix active materials, including supporting the active materials of the positive and negative plates, conducting the entire plate, and absorbing the mechanical pressure of the battery during the cycle process. During the casting process, due to the influence of the quality of the release agent, the grid often has problems such as demoulding difficulties, too fast increase in grid mass, cracks, pores, and uneven thickness.

[0003] Release agent is a spray coating used during casting. It is sprayed on the mold surface and forms a certain thickness of isolation layer on the mold surface. The main function of release agent is to form an isolation layer on the mold surface, which protects the mold while allowing the finished prototype to be cleanly and quickly separated from the mold. The evaluation criteria for release agent performance are mainly reflected in adhesion ability and film-forming isolation ability. Adhesion ability refers to the ability of release agent to firmly adhere to the mold surface, while film-forming isolation ability refers to the ability of release agent to evenly cover the mold surface to form an isolation film.

[0004] In the current grid casting process, the main components of the release agent used are bone glue, polyvinyl alcohol, cork powder and pure water, which are prepared into a release agent according to a specific process. The patent application with publication number CN 107511448 A discloses a release agent for lead-acid battery grid casting and a preparation method thereof. By adding volcanic ash, the release agent is reduced from falling off too quickly, the durability of the release agent is increased, the time interval of spraying during grid casting is extended, the work efficiency is improved, and the stability of the grid weight is improved. The addition of water-based phenolic resin has the advantages of heat resistance, flame resistance, water resistance and insulation.

[0005] However, there are still problems such as poor exhaust during the pouring process, resulting in low grid forming rate and many pores; the temperature is too high during pouring, causing the release agent to be burned quickly; and the conventional release agent has slow heat dissipation and a long cooling time, resulting in low production efficiency. Summary of the invention

[0006] The object of the present invention is to provide a battery grid casting release agent and a preparation process thereof, so as to enhance the adhesion ability and film-forming isolation ability of the release agent and improve production efficiency.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A battery grid casting demoulding agent comprises, by weight, 0.8-1.2 parts of bone glue, 0.8-1.2 parts of polyvinyl alcohol, 1-2 parts of cork powder, 2-4 parts of diatomaceous earth, 0.2-0.6 parts of modified nano silicon dioxide, 0.2-0.4 parts of polymer and 70-75 parts of water.

[0009] Furthermore, the modified nano-silicon dioxide is prepared by the following steps:

[0010] Disperse 10-12 parts of nano-silicon dioxide and 2-3 parts of surface modifier into 100-110 parts of water to obtain a dispersion, adjust the pH with 30% by mass NaOH, heat to 65-70° C. and stir for 6-6.5 hours, filter, wash with water and ethanol until neutral, dry and grind to obtain modified nano-silicon dioxide.

[0011] Furthermore, the surface modifier is one of sodium dodecyl sulfate and sodium dodecyl sulfonate.

[0012] Furthermore, the pH of the dispersion is adjusted to 10-11.

[0013] Furthermore, the particle size of the cork powder is 170-200 meshes.

[0014] Furthermore, the polymer is one of polyurethane, polyacrylate and polyethylene terephthalate.

[0015] A preparation process for a battery grid casting release agent comprises the following steps:

[0016] Add bone glue, polyvinyl alcohol and modified nano-silica into water, heat and stir for 1 to 1.5 hours, then add cork powder, diatomaceous earth and polymer, and continue stirring for 2 to 2.5 hours to prevent agglomeration and fully dissolve it. After cooling, a battery grid casting release agent is obtained.

[0017] Furthermore, the heating temperature is 70-80°C. DETAILED DESCRIPTION

[0018] Beneficial effects of the present invention:

[0019] (1) The modified nano-silica used in the present invention can effectively improve the heat resistance of the release agent. The modified nano-particles have improved dispersibility and reduced aggregation. When powdered materials of different components are added to the release agent, the higher the uniformity and dispersion of each material, the greater its surface free energy, the stronger its particle migration and diffusion power, and the more conducive to sintering. In addition, the modified nano-silica can effectively increase the adhesion between the release agent and the mold because of the presence of sodium ions, thereby enhancing the polarity of the release agent.

[0020] (2) The polymer used in the present invention physically adsorbs with the silanol groups (-Si-OH) on the surface of diatomite through hydrogen bonding, and at the same time, the polar groups (such as hydroxyl, carboxyl, amino, etc.) in the polymer chemically bond with the polar groups on the surface of the mold to form a "bridging" effect, which reduces the transfer of diatomite to the molded product and reduces the shedding of the release agent; on the other hand, the film formed by the polymer can provide a smooth and glossy appearance for the mold surface, thereby improving the quality of the finished product.

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0022] Example 1

[0023] This embodiment provides a battery grid casting release agent, which is prepared by the following steps:

[0024] The first step is to prepare modified nano-silica. 10 parts of nano-silica and 2 parts of sodium dodecyl sulfate are dispersed in 100 parts of water to obtain a dispersion, the pH is adjusted to 11 with 30% by mass NaOH, heated to 70°C and stirred for 6 hours, filtered, repeatedly washed with water and ethanol until neutral, dried and ground to obtain modified nano-silica.

[0025] In the second step, 1 part of bone glue, 1.2 parts of polyvinyl alcohol and 0.4 parts of modified nano-silica are added to 75 parts of water, heated to 80°C and stirred for 1.5 hours, and then 1 part of cork powder, 2 parts of diatomaceous earth and 0.2 parts of polyurethane are added, and stirring is continued for 2.5 hours to prevent agglomeration and fully dissolve it; after cooling, the battery grid casting release agent is obtained.

[0026] Example 2

[0027] The present embodiment is different from the embodiment 1 in that the "sodium lauryl sulfate" in the first step is changed to "sodium lauryl sulfonate".

[0028] The remaining raw materials and preparation process remain the same as in Example 1.

[0029] Example 3

[0030] The difference between this embodiment and embodiment 1 is that the "polyurethane" in the second step is changed to "polyethylene terephthalate".

[0031] The remaining raw materials and preparation process remain the same as in Example 1.

[0032] Example 4

[0033] The present embodiment is different from the embodiment 1 in that “2 parts of diatomaceous earth” is changed to “4 parts of diatomaceous earth”.

[0034] The remaining raw materials and preparation process remain the same as in Example 1.

[0035] Example 5

[0036] The present embodiment is different from the embodiment 1 in that “0.4 parts of modified nano-silicon dioxide” is changed to “0.2 parts of modified nano-silicon dioxide”.

[0037] The remaining raw materials and preparation process remain the same as in Example 1.

[0038] Comparative Example 1

[0039] The difference between this embodiment and embodiment 1 is that the pH adjustment step in the first step is removed.

[0040] The specific implementation steps are as follows: Step 1, prepare modified nano-silicon dioxide. Disperse 10 parts of nano-silicon dioxide and 2 parts of sodium dodecyl sulfate into 100 parts of water to obtain a dispersion, heat to 70°C and stir for 6 hours, filter, repeatedly wash with water and ethanol until neutral, dry and grind to obtain modified nano-silicon dioxide.

[0041] The remaining raw materials and preparation process remain the same as in Example 1.

[0042] Comparative Example 2

[0043] The difference between this comparative example and Example 1 is that no modified nano-silicon dioxide is added.

[0044] The remaining raw materials and preparation process remain the same as in Example 1.

[0045] Comparative Example 3

[0046] The difference between this comparative example and Example 1 is that no polymer is added.

[0047] The remaining raw materials and preparation process remain the same as in Example 1.

[0048] Comparative Example 4

[0049] The present embodiment is different from the embodiment 1 in that the "diatomaceous earth" in the second step is replaced with "cork powder".

[0050] The specific implementation steps are: in the second step, add 1 part of bone glue, 1.2 parts of polyvinyl alcohol and 0.4 parts of modified nano-silicon dioxide to 75 parts of water, heat to 80°C and stir for 1 to 1.5 hours, then add 3 parts of cork powder and 0.2 parts of polyurethane, and continue stirring for 2.5 hours to prevent agglomeration and allow it to fully dissolve; after cooling, obtain the battery grid casting release agent.

[0051] The remaining raw materials and preparation process remain the same as in Example 1.

[0052] The performance tests were conducted on Examples 1 to 5 and Comparative Examples 1 to 4. The viscosity of the release agent was measured using a digital viscometer. The casting speed and demoulding effect were tested, as well as the use time of a single spray mold.

[0053] The results are shown in Table 1:

[0054] Table 1

[0055]

[0056] It can be seen from Table 1 that, compared with Example 1, although the increase in the diatomaceous earth content in Example 4 can make the overall heat dissipation of the release agent better, with a higher casting speed and single use time, too much diatomaceous earth also leads to more pits in the demolded finished product; compared with Example 1, the reduction in the amount of modified nano-silicon dioxide added in Example 5 will lead to a decrease in the overall performance of the release agent.

[0057] Compared with Example 1, Comparative Example 1 mainly shows a decrease in viscosity, which is because nano-silicon dioxide can be better modified by surfactants when it is dissolved in an alkaline environment; Compared with Example 1, after not adding modified nano-silicon dioxide, the impact on the release agent in Comparative Example 2 is mainly reflected in the decrease in viscosity and the use time, because modified nano-silicon dioxide can not only improve heat resistance, but the presence of sodium ions can enhance the polarity of the release agent, effectively increasing the adhesion between the release agent and the mold; and because the high degree of uniformity and dispersion is conducive to sintering, the decrease in the demoulding effect of the finished product proves this. Compared with Example 1, after not adding polymer, the bridging effect between diatomite and the mold and the film-forming effect of the polymer disappear, which directly leads to more concave points in the demoulding of the finished product; Compared with Example 1, Comparative Example 4 has better heat dissipation effect and heat resistance than cork powder, so after replacing diatomite with cork powder, the casting speed and the use time of a single spray mold decrease.

[0058] In summary, the present invention provides a battery grid casting release agent and a preparation process thereof, which enhances the adhesion and film-forming isolation capabilities of the release agent by modifying nano-silicon dioxide and adding polymers to treat diatomaceous earth, and has good application prospects in industrial production.

[0059] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A battery grid casting release agent, characterized in that: The invention comprises, by weight, 0.8 to 1.2 parts of bone glue, 0.8 to 1.2 parts of polyvinyl alcohol, 1 to 2 parts of cork powder, 2 to 4 parts of diatomaceous earth, 0.2 to 0.6 parts of modified nano silicon dioxide, 0.2 to 0.4 parts of polymer and 70 to 75 parts of water.

2. A battery grid casting release agent according to claim 1, characterized in that: The modified nano silicon dioxide is prepared by the following steps: Disperse 10-12 parts of nano-silicon dioxide and 2-3 parts of surface modifier into 100-110 parts of water to obtain a dispersion, adjust the pH with 30% by mass NaOH, heat to 65-70° C. and stir for 6-6.5 hours, filter, wash with water and ethanol until neutral, dry and grind to obtain modified nano-silicon dioxide.

3. A battery grid casting release agent according to claim 2, characterized in that: The surface modifier is one of sodium dodecyl sulfate and sodium dodecyl sulfonate.

4. A battery grid casting release agent according to claim 2, characterized in that: The pH of the dispersion is adjusted to 10-11.

5. A battery grid casting release agent according to claim 1, characterized in that: The particle size of the cork powder is 170-200 meshes.

6. A battery grid casting release agent according to claim 1, characterized in that: The polymer is one of polyurethane, polyacrylate and polyethylene terephthalate.

7. A process for preparing a battery grid casting release agent as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Add bone glue, polyvinyl alcohol and modified nano-silica into water, heat and stir for 1 to 1.5 hours, then add cork powder, diatomaceous earth and polymer, and continue stirring for 2 to 2.5 hours to prevent agglomeration and fully dissolve it. After cooling, a battery grid casting release agent is obtained.

8. The process for preparing a battery grid casting release agent according to claim 7, characterized in that: The heating temperature is 70-80°C.

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