大豆多糖-异氰酸酯微胶囊改性大豆基胶黏剂

A research on soy polysaccharide-isocyanate microcapsule-modified soy-based adhesives

为获得耐水性优良的木材工业用大豆基胶黏剂,以大豆多糖包覆异氰酸酯树脂的微胶囊改性脱脂豆粉制备大豆基胶黏剂,并研究其胶合强度、韧性、表面疏水性和热稳定性。结果表明:该方法制备的大豆多糖-异氰酸酯微胶囊球形度好,结构完整,粒径分布均匀,对芯材具有很好的保护效果。微胶囊改性大豆基胶黏剂固化后的韧性、表面疏水性和热稳定性提高。傅里叶变换红外光谱仪分析表明,异氰酸酯官能团与外层的水和大豆多糖上的羟基发生反应,形成氨基甲酸酯和脲交联,从而包裹内部未反应的异氰酸酯组分形成微胶囊;微胶囊热压破裂后异氰酸酯与胶黏剂其他组分发生类似反应,形成交联,提高胶黏剂固化后的耐水性能。优化得到800 r·min^-1制备的微胶囊,以20%的用量改性大豆基胶黏剂,在0.59 min·mm^-1、1.0 MPa、130℃的热压工艺下,压制的巨尾桉胶合板的胶合强度为0.95 MPa,达到国家标准GB/T 9846—2015中室内用Ⅱ类胶合板的要求。

To obtain a highly water-resistant soy-based adhesive for the wood industry,the bonding strength,toughness,surface hydrophobicity,and thermal stability of microcapsule-modified soy-based adhesives were investigated;the microcapsule was isocyanate resin encapsulated with soybean polysaccharide.The results revealed that prepared soybean polysaccharide-isocyanate microcapsules have good sphericity,structure,and size distribution and can provide a good protective effect to core materials.Microcapsule-modified soy-based adhesives can effectively improve the toughness,surface hydrophobicity,and thermal stability after curing.FTIR analysis showed that isocyanate groups reacted with water on the outer layer and hydroxyl groups of soy polysaccharide to form carbamate and urea crosslinks,hence encapsulating the internal unreacted isocyanate components to form microcapsules.Similar chemical reactions occurred between the isocyanate resin and other components of the adhesive after microcapsule breakdown,resulting in a better water resistance of the cured adhesive.An optimized formula of soy-based adhesive was added to 20%of the microcapsule,which was prepared at 800 r·min^-1.When plywood bonded with the adhesives under the following conditions:hot pressing time of 0.59 min·mm^-1,hot pressing pressure of 1.0 MPa,and hot pressing temperature of 130℃,the bonding strength was 0.95 MPa,which meets the Chinese National Standard GB/T 9846—2015 for interior plywood.