Preparation method of E0-grade melamine modified urea formaldehyde resin

Abstract

The invention provides a preparation method of E0-grade melamine modified urea formaldehyde resin. According to the preparation method, formaldehyde, urea, polyvinyl alcohol and melamine are selected as main raw materials; urea is added in three batches, so that the molar ratios of the first, second and third batches of urea to formaldehyde are 1:2.24, 1:1.54 and 1:0.95 respectively; polyvinyl alcohol and melamine are respectively added into a reaction kettle before and during an addition reaction, so that the raw materials can be subjected to reactions in four media of which the pH values are 7.5-8.0, 5.1-5.0, 6.2-6.5 and 8.0-8.5 respectively; finally, E0-grade melamine modified urea formaldehyde resin is prepared. The preparation method has the advantages that addition of a formaldehyde catching agent is not needed; the preparation process is simple; the bonding strength, the waterproof property and the pre-pressing effect of the product, namely E0-grade melamine modified urea formaldehyde resin, are improved; the E0-grade requirement for free formaldehyde can be met; the market application range is broad.

Description

technical field [0001] The invention relates to the technical field of urea-formaldehyde resin production, in particular to E0 grade melamine-modified urea-formaldehyde resin for interior decorative boards. Background technique [0002] Urea-formaldehyde resin is the most widely used adhesive in the wood industry. The urea-formaldehyde resin produced from urea and formaldehyde by conventional methods has a high free formaldehyde content, and there are inevitably a large number of methylol and ether bonds in the resin molecule. Causes of formaldehyde release and poor water resistance during the curing process of wood-based panels. [0003] Urea-formaldehyde resin is actually a mixture of free formaldehyde, methylol urea, urea-formaldehyde polymer and methylolated urea-formaldehyde. The formaldehyde release of wood-based panels made of urea-formaldehyde resin mainly comes from: free formaldehyde of urea-formaldehyde resin, and urea-formaldehyde resin during hot-press curing. ...

AI Technical Summary

Problems solved by technology

In order to solve the problem of high free formaldehyde, in recent years, the method of reducing the molar ratio of formaldehyde and urea is mainly used to produce urea-formaldehyde resin with low free formaldehyde content, but the urea-formaldehyde resin produced in this way has poor bonding strength, storage stability and water solubility.

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