碱性条件下脲醛树脂胶黏剂体系竞争反应的ESI-MS研究

Competitive Reaction of Urea-formaldehyde Resin Adhesive under Alkaline Conditions by ESI-MSLIANG

采用电喷雾电离质谱(ESI-MS)技术深入解析尿素-甲醛(UF)在碱性体系中化学结构的分布情况,揭示UF在碱性体系的反应规律。结果表明:1)UF碱性体系中羟甲基化结构主要有二羟甲基脲、一羟甲基脲和三羟甲基脲。其含量高低为二羟甲基脲>一羟甲基脲>三羟甲基脲。四羟甲基脲难以形成,但可以产生类似于四羟甲基脲的二羟甲基Uron结构。2)羟甲基脲之间发生缩合反应形成真正意义醚键结构R 1-CH 2-O-CH 2-R 2,但并不完全是半缩醛结构(R-CH 2-O-CH 2OH),且同系物分布符合高斯分布规律。3)反应温度的升高并不能增加羟甲基脲的缩合程度,缩聚物的形成、分布及含量与反应历程有关。该研究工作的开展为UF碱性反应历程的解析提供有效的数据和理论支撑,同时也拓展了ESI-MS在UF体系的结构和反应历程上的应用。

Electrospray ionization mass spectrometry(ESI-MS)was used to analyze the distribution of various structures in urea-formaldehyde(UF)alkaline system and to reveal the reaction regularity of UF system.The results showed that the proportions of the structures that were detected in the system were were in the order of dihydroxymethyl urea>monohydroxymethyl urea>trihydroxymethyl urea.Tetrahydroxymethyl urea was difficult to form,but it could produce dihydroxymethyl uren structure similar to tetrahydromethyl urea.Real ether bond structure R 1-CH 2-O-CH 2-R 2 was formed by the condensation reaction between hydroxymethyl urea,but it was not completely semi-acetal structure(R-CH 2-O-CH 2OH),and the homologue distribution conformed to the Gauss distribution law.The condensation degree of hydroxymethylurea did not increase with the increase of reaction temperature.The formation,distribution and contents of the condensates were related to the reaction process.The research results would provide effective data and theoretical support for the analysis of UF alkaline reaction process and expand the application of ESI-MS in the structure and reaction process of UF system.