Modified urea-formaldehyde resin adhesive for plywood and preparation method thereof

Abstract

The invention discloses a modified urea formaldehyde resin adhesive for veneer sheets and a preparation method thereof. Formaldehyde and urea in low mole ratio are used as raw materials, a polyfunctional reaction enhancer is used as a polycondensation agent instead of the acidic polycondensation agent, and an acid-alkali-acid technique is utilized to synthesize the urea formaldehyde resin, thereby enhancing the molecular branching degree of the urea formaldehyde resin, increasing the molecular weight of the urea formaldehyde resin under the condition of the same viscosity, enhancing the curing crosslinking density of the urea formaldehyde resin, further enhancing the bonding strength and lowering the formaldehyde release amount of the bonded product. The basic process is approximate to the common technique. The method is simple in technique and easy to operate, and does not need to modify the existing equipment.

Description

technical field [0001] The invention relates to the field of adhesives and preparation thereof, in particular to a modified urea-formaldehyde resin adhesive for plywood and a preparation method thereof. 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 m 3 , accounting for about 50% of the world's total production. Average production of 9m per ton of adhesive 3 According to the calculation of wood-based panels, the consumption of wood adhesives in my country in 2013 was about 30 million tons (solid content 50%), among which urea-formaldehyde resin and its modified products...

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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