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CN-122007325-A - Shelling-proof precoated sand prepared from reclaimed sand and preparation method thereof

CN122007325ACN 122007325 ACN122007325 ACN 122007325ACN-122007325-A

Abstract

The application relates to the technical field of precoated sand production, and particularly discloses anti-unshelling precoated sand prepared from reclaimed sand and a preparation method thereof. The shellproof precoated sand prepared from the reclaimed sand comprises, by weight, 100 parts of modified reclaimed sand, 15-25 parts of phenolic resin, 1-2 parts of nano alumina powder, 7-9 parts of urotropine aqueous solution and 1-2 parts of calcium stearate, wherein the modified reclaimed sand is prepared by synergistic modification of a surface reconstruction agent and a hybrid coupling agent. The shelling-proof precoated sand can be used for producing the precoated sand, and has the advantages of improving the surface characteristics of the reclaimed sand, enhancing the interfacial binding force between the reclaimed sand and resin and the uniformity of the precoated sand, and further avoiding the occurrence of the shelling phenomenon of a sand core.

Inventors

  • REN WENHU

Assignees

  • 柳州柳晶环保科技有限公司

Dates

Publication Date
20260512
Application Date
20260202

Claims (10)

  1. 1. The shellproof precoated sand is characterized by comprising, by weight, 100 parts of modified reclaimed sand, 15-25 parts of phenolic resin, 1-2 parts of nano alumina powder, 7-9 parts of urotropine aqueous solution and 1-2 parts of calcium stearate, wherein the modified reclaimed sand is prepared by synergistically modifying the reclaimed sand through a surface reconstruction agent and a hybrid coupling agent, and the mass ratio of the reclaimed sand to the surface reconstruction agent to the hybrid coupling agent is 100 (3-7) (0.6-0.8).
  2. 2. The shellproof precoated sand prepared by using the reclaimed sand as claimed in claim 1, wherein the modified reclaimed sand is prepared by pretreating reclaimed sand to be neutral or weak acid, heating, spraying a surface reconstruction agent in the stirring process, introducing 100 ℃ water vapor for reaction, drying after the reaction is completed, spraying a hybridization coupling agent, and uniformly mixing to obtain the modified reclaimed sand.
  3. 3. The shellproof precoated sand produced by using the reclaimed sand as claimed in claim 2, wherein the pretreatment process comprises stirring the reclaimed sand with a mass ratio of (2-4): 100 with an aqueous solution of citric acid of 4wt% to 6wt% for 8-12min.
  4. 4. An anti-unshelling precoated sand made from reclaimed sand as claimed in claim 2, wherein the drying temperature is 115-125 ℃.
  5. 5. An anti-unshelling precoated sand made from reclaimed sand as claimed in claim 2 wherein the surface restructuring agent comprises an ammonium fluorotitanate ethanol solution or an ammonium fluorozirconate ethanol solution and the hybrid coupling agent comprises a silane-butadiene hybrid polymer.
  6. 6. The shellproof precoated sand produced with reclaimed sand as claimed in claim 5, wherein the concentration of the ammonium fluorotitanate ethanol solution or ammonium fluorozirconate ethanol solution is 4wt% to 6wt%.
  7. 7. The shellproof precoated sand prepared with reclaimed sand as claimed in claim 5, wherein the silane-butadiene hybrid polymer is prepared by the steps of: Placing 95-105 parts of triethoxysilane and 290-310 parts of anhydrous toluene into a reaction kettle, introducing nitrogen for replacement, dropwise adding 0.05-0.15 part of catalyst under stirring, heating to 48-52 ℃ and preserving heat for 8-12 minutes, dropwise adding 28-32 parts of liquefied butadiene, maintaining the temperature at 50-60 ℃, heating to 70 ℃ after the dropwise adding is finished, preserving heat for 2-4 hours, and distilling under reduced pressure to obtain the silane-butadiene hybrid polymer.
  8. 8. The shellproof precoated sand made of reclaimed sand as claimed in claim 7, wherein the catalyst is a chloroplatinic acid solution.
  9. 9. The shellproof precoated sand prepared with reclaimed sand as claimed in claim 1, wherein the concentration of urotropin aqueous solution is 14-16 wt%.
  10. 10. A method for preparing the shellproof precoated sand prepared from reclaimed sand as claimed in any one of claims 1 to 9, comprising the steps of: Heating the modified reclaimed sand to 145-155 ℃ for mixing sand, adding phenolic resin, stirring for 25-35s, then adding nano alumina powder for mixing sand for 15-25s, then adding urotropine water solution for mixing sand for 35-45s, and finally adding calcium stearate for mixing sand for 25-35s to obtain the precoated sand.

Description

Shelling-proof precoated sand prepared from reclaimed sand and preparation method thereof Technical Field The application relates to the technical field of precoated sand production, in particular to anti-unshelling precoated sand prepared from reclaimed sand and a preparation method thereof. Background In the field of casting production, the precoated sand has the advantages of high strength, good fluidity, good collapsibility and the like, and is widely applied to the preparation of sand cores and casting molds. The core preparation principle of the precoated sand is that a binding system such as resin, a curing agent and the like is uniformly coated on the surface of sand grains to form precoated sand particles with specific properties, and the performance quality of the precoated sand particles directly depends on the bonding strength and coating uniformity between the sand grains and the resin. Natural quartz sand is a traditional raw material for preparing precoated sand, but with the increasing exhaustion of natural sand resources and the trend of environmental protection policy, the recycling of foundry waste sand becomes a necessary trend of industry development, and the replacement of the natural sand by the recycled sand also gradually becomes a research hot spot. In the actual production process, when the reclaimed sand is directly adopted to prepare the precoated sand, the technical problem of poor combination property of sand grains and resin is generally faced. The analysis is that the clay oolitic layer or the inertized water glass layer which is accumulated on the surface of the reclaimed sand and cannot be completely removed is poor in bonding capability with resin, uneven adhesion is caused on the surface of sand grains during film coating, and a shelling phenomenon is easy to generate during sand core manufacturing, so that production loss is caused. Therefore, how to effectively improve the surface characteristics of the reclaimed sand, enhance the interfacial bonding force between the reclaimed sand and resin and the uniformity of the film coating, and further avoid the occurrence of the phenomenon of sand core shelling is a technical bottleneck to be solved in the prior art when the reclaimed sand is used for preparing the film coating sand. Disclosure of Invention In order to effectively improve the surface characteristics of the reclaimed sand, enhance the interfacial binding force between the reclaimed sand and resin and the uniformity of the coating, and further avoid the occurrence of the sand core shelling phenomenon, the application provides the shelling-preventing coated sand prepared by the reclaimed sand and a preparation method thereof. In a first aspect, the application provides an anti-unshelling precoated sand prepared from reclaimed sand, which adopts the following technical scheme: The shellproof precoated sand prepared from the reclaimed sand comprises, by weight, 100 parts of modified reclaimed sand, 15-25 parts of phenolic resin, 1-2 parts of nano alumina powder, 7-9 parts of urotropine aqueous solution and 1-2 parts of calcium stearate, wherein the modified reclaimed sand is prepared by synergistically modifying the reclaimed sand through a surface reconstruction agent and a hybridization coupling agent, and the mass ratio of the reclaimed sand to the surface reconstruction agent to the hybridization coupling agent is 100 (3-7) (0.6-0.8). By adopting the technical scheme, as clay and a water glass layer are usually remained on the surface of the reclaimed sand, the film coating effect is poor easily, the reclaimed sand is modified by adopting the ammonium fluotitanate as the surface reconstruction agent, micro-lines are etched on the surface of the sand by utilizing the hydrolysate of the ammonium fluotitanate, the surface energy of the reclaimed sand is improved, ti-OH roots can be deposited on the surface of the sand, the unclean surface of the reclaimed sand is converted into a high-activity surface, and the reclaimed sand is easier to combine with organic matters. In addition, silane-butadiene hybrid polymer is used as a hybrid coupling agent to modify the reclaimed sand, one end of the silane-butadiene hybrid polymer molecule is combined with Si-OH and Ti-OH on the sand surface, and the other end of the silane-butadiene hybrid polymer molecule is combined with a resin organic group, so that the combination capability of the resin and the reclaimed sand surface is greatly enhanced, and the shelling tendency of the precoated sand is reduced. According to the application, nano alumina powder is added, on one hand, the alumina powder with extremely high melting point can help the resin resist the burning of high-temperature molten metal (> 1500 ℃) to prevent sand from being stuck into the sand mould, and on the other hand, the alumina powder particles with extremely high strength can help the sand mould resist the microcrack of the sand mould caused by thermal str