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Precoated sand composition and preparation method thereof

A technology of composition and coated sand, which is applied in the direction of manufacturing tools, casting molding equipment, metal processing equipment, etc., can solve the problems of large energy consumption, long curing time, and incomplete curing of coated sand, so as to improve production efficiency, The effect of reducing energy consumption and fast curing

Inactive Publication Date: 2013-04-10
HEFEI RENCHUANG CASTING MATERIAL CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, because the existing phenolic resin coated sand needs to be cured at high temperature (usually higher than 200°C), and the curing time is relatively long, it needs to consume a lot of energy, causing great cost and environmental pressure to the factory.
[0004] Although the traditional thermosetting phenolic resin can be partially cured at low temperature, after the traditional thermosetting phenolic resin is combined with sand to form coated sand, the coated sand cannot be completely cured and formed at a lower curing temperature, which will cause subsequent casting. a series of questions

Method used

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  • Precoated sand composition and preparation method thereof
  • Precoated sand composition and preparation method thereof
  • Precoated sand composition and preparation method thereof

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preparation example Construction

[0039] The present invention also provides a kind of preparation method of coated sand composition, and this method comprises the following steps:

[0040] (1) under the synthetic condition of phenolic resin, formaldehyde, phenol and modified component are mixed contact, obtain modified phenolic resin, and described modified component is the reaction product of caprolactam and isocyanate and / or resorcinol, The isocyanate is aliphatic isocyanate and / or aromatic isocyanate;

[0041] (2) Silica sand and the modified phenolic resin are mixed, and then cured.

[0042] Preferably, the modified component in step (1) is a reaction product of caprolactam and isocyanate, or a mixture of a reaction product of caprolactam and isocyanate and resorcinol. In this case, the conditions for the reaction of caprolactam and isocyanate preferably include: a reaction temperature of 50-110°C, more preferably 70-100°C; a reaction time of 1-20 hours, more preferably 5-10 hours; caprolactam and isocya...

Embodiment 1

[0057] This example is used to illustrate the coated sand composition and its preparation method of the present invention.

[0058] (1) Preparation of modified phenolic resin

[0059] 5.65 g (0.05 mol) of caprolactam and 9.86 g (0.05 mol) of o-toluene isocyanate were reacted at 90° C. for 10 hours. Then, the reaction product obtained, 94g (1mol) of phenol, 21g (0.7mol) of formaldehyde and 1g of oxalic acid were added to the reactor, heated to 100°C with stirring, and reacted at this temperature for 5 hours to obtain the modified Reactive phenolic resin. Detect the weight-average molecular weight of this modified phenolic resin according to gel permeation chromatography, and in conjunction with the nuclear magnetic resonance spectrum data of this modified phenolic resin can calculate, the average degree of polymerization of this modified phenolic resin is about 6, and the modified phenolic resin The content of the repeating unit represented by the above formula (I) in the phe...

Embodiment 2

[0071] This example is used to illustrate the coated sand composition and its preparation method of the present invention.

[0072] Prepare modified phenolic resin and coated sand according to the method of embodiment 1, difference is, in step (1), replace the reaction product of caprolactam and o-toluene isocyanate with the resorcinol of 15.5g, thereby prepare The resulting sheet sand-based product A2 had a degree of cure of about 79%.

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Abstract

The invention relates to a precoated sand composition, which comprises silica sand and modified phenolic resin, wherein the modified phenolic resin comprises repeating units shown in a formula (I) and a formula (II). The invention further relates to a preparation method of the precoated sand composition, which comprises the following steps of: step (1), mixing and contacting formaldehyde, phenol and a modified component together under a synthesis condition of phenolic resin to obtain modified phenolic resin, wherein the modified component is a reaction product of hexanolactam and isocyanate and / or resorcinol, and the isocyanate is aliphatic isocyanate and / or aromatic isocyanate; and step (2), mixing the silica sand with the modified phenolic resin and then curing. The precoated sand composition disclosed by the invention can realize quick curing at a low temperature, thereby reducing the energy consumption in curing, increasing the production efficiency and lowering the production cost.

Description

technical field [0001] The invention relates to a coated sand composition and a preparation method of the coated sand composition. Background technique [0002] Traditional coated sand is produced by mechanically mixing powdered phenolic resin with raw sand, followed by heat curing. This coated sand is used in the foundry industry as a material for making molds and cores. After that, people continued to research and developed phenolic resin coated sand with various uses such as high strength, high temperature resistance, easy collapse, low gas generation, chilling, wet state, and centrifugal casting. Phenolic resin coated sand has the characteristics of low cost, easy operation, stable process, and good fluidity of molding sand. Using the phenolic resin coated sand casting process, it can mass-produce steel, iron and aluminum alloy castings with smooth surface and high dimensional accuracy. The castings produced have high dimensional accuracy, good surface quality and high ...

Claims

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Application Information

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IPC IPC(8): B22C1/22B22C5/04
Inventor 秦升益龙御云
Owner HEFEI RENCHUANG CASTING MATERIAL CO LTD
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