A kind of modified urea-formaldehyde resin adhesive and preparation method thereof

Abstract

The invention discloses a modified urea resin adhesive and a preparation method thereof. According to the preparation method, formaldehyde and urea in a low molar ratio are taken as raw materials, and a poly-functionality reaction enhancer is taken as a polycondensation agent to replace an acidic polycondensation condition, and the urea resin is synthesized by use of an acid-alkali-acid process; the molecular branching coefficient of the urea resin is increased, the molecular weight of the urea resin is increased under the same viscosity, and the curing cross-linking density of the urea resin can be increased, and furthermore, the bonding strength is improved and the formaldehyde release amount of the bonded products is reduced. The preparation method of the low-toxicity urea resin adhesive has the advantages that non-traditional melamine-epoxy chloropropane-sodium hydroxide reactants are taken as polycondensation agents and the acid-alkali-acid synthesis process is adopted, the basic procedure is close to the conventional process, the process is simple, the operations are convenient, and the existing equipment does not need to be modified.

Description

technical field [0001] The invention relates to an adhesive, in particular to a modified urea-formaldehyde resin adhesive used for preparing wood-based panels and a preparation method thereof, belonging to the field of adhesives. Background technique [0002] With the improvement of people's living standards and the continuous and stable development of construction, decoration, packaging and other industries, the output of wood-based panels in my country has grown rapidly. The total output of wood-based panels, plywood, furniture, and wood flooring has ranked first in the world for many years in a row. In 2013, the total output of wood-based panels in my country was 272 million m3, accounting for about 50% of the world's total output. Based on the average production of 9m3 wood-based panels per ton of adhesive, the consumption of wood adhesives in my country in 2013 was about 30 million tons (solid content 50%), of which urea-formaldehyde resin and its modified products acc...

AI Technical Summary

Problems solved by technology

For example: 1) Although the use of low molar ratio modified urea-formaldehyde resin adhesives can effectively reduce the formaldehyde emission of wood-based panel products, the bonding strength of the products is often reduced, which cannot meet the requirements of use; and it can lead to prolonged curing time and reduced production efficiency; 2) Adding formaldehyde scavenger to urea-formaldehyde resin adhesives for wood-based panels can effectively reduce the release of free formaldehyde from wood-based panels, but it often reduces the bonding strength of wood-based panels at the same time; at the same time, the price of general formaldehyde scavenger is often much higher than that of urea-formaldehyde resin adhesives. Adding improves product cost and reduces product competitiveness; 3) Carry out post-processing to wood-based panels, as the invention patent application with publication number CN1526528 discloses a method for preparing E1 / EO grade environment-friendly wood-based panels using ammonia vacuum method. Manufacturing process; the utility model patent with publication number CN2394770 discloses a treatment device for reducing formaldehyde emission from wood-based panels. These post-processing methods not only make the manufacturing process of wood-based panels complicated, but also require huge investment in post-processing equipment and significantly increase production costs. ; 4) The use of other environmentally friendly adhesives, such as isocyanate adhesives, has led to a substantial increase in the production cost of wood-based panels and increased difficulty in the production process, which is difficult for enterprises and users to accept; the use of ordinary protein adhesives to prepare wood-based panels has low bonding strength and poor water resistance , easy to mold, poor sizing performance, easy to open glue for wood-based panels

In summary, although the above measures can effectively reduce the release of free formaldehyde from wood-based panels, they cannot completely solve the problem of formaldehyde release, or cannot be popularized due to reasons such as high production costs.

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