Urea-formaldehyde modified resin adhesive for bagasse shaving boards and preparation method thereof

Abstract

The invention discloses a urea-formaldehyde modified resin adhesive for bagasse shaving boards and a preparation method thereof. The urea-formaldehyde modified resin adhesive for bagasse shaving boards is composed of the following components in parts by weight: 3300 parts of formaldehyde, 60 parts of diethylene glycol, 1600 parts of urea, 20 parts of caprolactam, 2 parts of sodium hydroxide and 450 parts of water. On the basis of the traditional urea-formaldehyde resin alkali-acid-alkali synthesis technique, after the early stage extended reaction is performed on the first batch of urea, when the free formaldehyde content in the reaction solution is low, the diethylene glycol with higher reaction is added; in the later reaction stage, the pH value of the reaction solution is strictly controlled, so that the synthesis process is performed in a controllable way; and finally, the second batch of urea is added to capture free formaldehyde and further enhance the reaction degree of the reaction solution. The reaction process is smooth and controllable, and has favorable repeatability.

Description

technical field [0001] The invention belongs to the field of resin synthesis, and in particular relates to a urea-aldehyde-modified resin glue for bagasse particleboard and a preparation method thereof. Background technique [0002] The thickness of wood raw materials used to make glued wood is generally more than 20mm, and its length and width are larger, and wood is a poor conductor of heat. ) conditions, or set up a high-frequency heating device in the wood bonding section to increase the ambient temperature and speed up the chemical reaction speed of the adhesive cured under medium and high temperature conditions. However, considering the investment in high-frequency heating equipment and the stability of equipment operation, the adhesives used by domestic glulam manufacturers are room temperature curing adhesives. [0003] The wood structure adhesives that are fast curing at room temperature in the domestic market now include resorcinol-phenol-formaldehyde resin, resor...

AI Technical Summary

Problems solved by technology

[0004] (1) Most of the above five types of room temperature curing wood adhesives rely on foreign imports such as Japan and Finland. So far, the room temperature curing structural adhesives developed and produced by my country have not been used on a large scale in domestic wood structure projects. There are potential safety hazards in the sustainable and healthy development of wooden structural components;

[0005] (2) When resorcinol-phenol-formaldehyde resin and resorcinol-formaldehyde resin are used for the bonding of glued wood components, the bonding performance is excellent, but the glue seam is red and black, which is different from the conventional light color to be bonded. The appearance of wood is extremely uncoordinated, and the free phenolic substances contained in it have adverse effects on human health and the environment;

[0006] (3) The glulam components bonded by urea-formaldehyde resin meet the requirements of the standard specification when used in a dry state, and the price of the resin is low, but in the outdoor or indoor environment where the ambient temperature and humidity change rapidly, the resin is affected by the changing environment Large, the molecular chain is easily broken, the bond strength is lost quickly, and the application field is greatly limited;

[0007] (4) Melamine-formaldehyde resin has high activity, short storage period, high brittleness of the cured adhesive layer, insufficient toughness, and high price;

[0008] (5) There is no supply of room temperature curing melamine-urea-formaldehyde resin for glued wood in the domestic market;

[0009] (6) The price of polyurethane resin is generally 2-4 times that of resorcinol-phenol-formaldehyde resin, which brings difficulties to the cost control of domestic glued wood component manufacturers

[0011] Bagasse is the residue after sugar production. The chemical composition of the bagasse after removing the pith, due to the small specific gravity of the bagasse and good fiber quality, the prepared board has high strength, light weight and low water expansion rate, but the combination with urea-formaldehyde resin High requirements will not only affect the surface quality of the plywood, but also cause a decrease in the bonding strength of the plywood, resulting in cracks and bubbling