Environment-friendly low-formaldehyde wastewater-discharge-free furan resin and preparation method thereof

Abstract

The invention discloses environment-friendly low-formaldehyde wastewater-discharge-free furan resin and a preparation method thereof. The furan resin is prepared from the following components: 50-60 parts of furfuryl alcohol, 9-15 parts of formaldehyde, 8-12 parts of urea, 25-35 parts of treated wastewater, 0.2-0.5 part of ammonia water, 0.2-0.5 part of formic acid, 0.2-0.5 part of sodium hydroxide, 0.4-0.5 part of a coupling agent and 2-6 parts of methanol. The preparation method comprises the following steps: adding wastewater in a reactor, then adding 9-15 parts of formaldehyde, 6-10 parts of urea, and slowly adding sodium hydroxide to adjust the pH to 8-10; heating to 85-95 DEG C, carrying out heat preservation and reacting for 30-60 minutes, adding the rest of urea and 30-35 parts of furfuryl alcohol and slowly adding sodium hydroxide to adjust the pH to 8-10; heating to 85-95 DEG C, carrying out heat preservation and reacting for 30-60 minutes, and after the reaction is completed, carrying out vacuum dehydration; adding the rest of furfuryl alcohol and slowly adding formic acid to adjust the pH to 4-5; heating to 90-105 DEG C, carrying out heat preservation and reacting for 30-60 minutes, and after the reaction is completed, carrying out vacuum dehydration; adding 2-4 parts of tap water and stirring for 10-20 minutes and after the stirring is completed, carrying out vacuum dehydration; and cooling to below 60 DEG C, slowly adding ammonia water to adjust the pH to 6.5-7.5, further cooling to below 40 DEG C, adding methanol and the coupling agent, stirring for 10-20 minutes and filtering.

Description

technical field [0001] The invention relates to a synthetic resin binder for casting, in particular to an environment-friendly, low-aldehyde, no-wastewater discharge furan resin and a preparation method thereof. Background technique [0002] Furan resin is currently the most used casting molding binder in the world, accounting for more than 50% of the binder usage. The use of furan resin has been increasing at an annual rate of 10% in recent years, mainly because people have higher and higher requirements for the quality of castings in recent years, and furan resin has higher high-temperature strength, and the castings produced Compared with the original clay sand, the quality has been greatly improved; on the other hand, the reuse rate of the old sand of furan resin resin is high, which reduces the pollution of the old sand to the environment. [0003] The traditional furan resin is mainly prepared by addition reaction of 37% liquid formaldehyde and urea under alkaline con...

AI Technical Summary

Problems solved by technology

On the one hand, there are serious environmental protection problems in the existing process. According to the 8000L reactor, the nitrogen content of furan resin is about 5%, the water content is about 18%, and the waste water discharged per ton of product is about 260 kg, and the annual output is 12000 In terms of tons, 3120 tons of waste water will be produced a year, which is extremely harmful to the environment and extremely difficult to treat; on the other hand, in the traditional production method, the reaction between formaldehyde and urea is not complete, resulting in a high content of free formaldehyde in the resin. There will be formaldehyde volatilization, which not only pollutes the environment, but also endangers the health of operators.

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