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Lignin is a natural organic polymer, and its content is second only to cellulose in the plant kingdom, is a natural renewable resources. With the increasingly severe crisis of the world's resources and the continuous improvement of the ecological environment requirements, the research and application of lignin and its derivatives is more and more widespread attention at home and abroad. With the development of the timber industry, the adhesive industry in China has also been a great development. Wood adhesive products for industrial use in terms of production or the number of varieties, or in the quality of products, there is a lot of progress, but there are still some problems. Phenolic resin (phenol-formaldehyde? Resin? Hereinafter referred to as PF glue) as a polymer resin in the the the artificial sheet adhesive industry application of a wide range of excellent performance with high adhesive strength, strong water resistance, weather resistance, but there are also the high cost of raw materials, non-renewable sources of raw materials, and other shortcomings. Alkali lignin from the pulp and paper waste. Alkali lignin used in the preparation of the phenolic resin adhesive made from alkali lignin - lignin-formaldehyde phenolic resin (alkali?? Resin? Hereinafter referred to as? ALPF glue) adhesive alkali lignin instead of part of the price of expensive phenol synthetic polymer materials, with great economic and social significance. In this paper, first of all means of infrared spectroscopy, elemental analysis, testing alkali lignin chemical structure analysis. The results indicate that the alkali lignin containing more phenolic hydroxyl group, a part of the alcoholic hydroxyl group, a methyl group and methylene. Its structure with a phenol of a phenolic hydroxyl group with a similar structure can be used as synthetic materials ALPF gum. Secondly, by the reaction time, the reaction performance parameters such as temperature, wood / aldehyde ratio, PH of free formaldehyde and the methylol content, determined methylolated modified optimal conditions: 90 ° C, PH? for? 11.5, reaction time? 3.5h, wood / aldehyde? 4:1. The optimum conditions, methylol content by increasing the methylol content, effectively improve the reactivity of alkali lignin with formaldehyde. Been optimized not only effectively reduce the free formaldehyde content, also reached the efficient use of resources and environmental protection. Finally, replace 50% of alkali lignin phenol synthesis? ALPF glue. Performance indicators as free formaldehyde and free phenol, viscosity and adhesive strength, alkali, aldehydes dosage the urea amount of the above performance indicators. Studies have shown that when the amount of alkali? 4.5% aldehyde dosage? 12% urea? 2.5% of the optimal reaction conditions, the adhesive strength of the 2.37Mpa greater than the unmodified 2.11Mpa, free formaldehyde original 0.11% to 0.093% in the present, a free phenol content reduced to? 0.35%, the solid content reached? 49.2%, a viscosity of? 289mpa. s, performance optimization, especially urea join contributed to reduce the free formaldehyde and improve the adhesive strength, these studies provide a better theoretical basis for laboratory research and industrial application.
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