绿色成炭剂-多羟基改性蜜胺树脂的合成、 构效关系及作用机理研究

Intumescent flame retardant (IFR) is often considered as a class of green flame retardants with great development potential, and charring agent is one of the key components affecting the flame retardant effect of IFR. The flame retardancy of IFR has been improved markedly as the successful use of macromolecular triazine-based charring agents, but the triazine-based charring agents used currently also have some deficiencies, such as high chlorine content, serious environmental pollution in its synthesis process and unsatisfactory carbonization effect. In order to address the above problem, a type of novel green triazine-based charring agents — polyhydroxy modified melamine formaldehyde resin, together with its green synthetic route, has been designed on the basis of the action mechanism of IFR, the structure characteristics of triazine-based charring agents and the basic principles of green chemistry, which were synthesized by grafting traditional charring agents - polyols onto melamine formaldehyde resin. A series of the polyhydroxy modified melamine formaldehyde resin will be synthesized in the project, and from which several high efficient green charring agents will be screened out once their flame retardancy has been detailedly and systematically evaluated. Their action mechanisms will also be studied by identifying the composition and chemical structure of thermal decomposition products and combustion residues as well as theoretical analysis. Their quantitative structure-property relationship model would be built by multiple linear regression. Accordingly, the new thinking for the molecular design of high efficient green charring agents will be proposed, which will provide a theoretical guidance for the development of more high efficient green charring agents.

膨胀型阻燃剂（IFR）被认为是一种具有发展潜力的绿色阻燃剂,而成炭剂是影响其阻燃效果的关键物质之一。大分子三嗪成炭剂的成功应用使IFR的阻燃性能得到了显著提高，但它也存在产品氯含量高、合成过程中环境污染严重、成炭效果仍不理想等问题。针对以上问题，本项目根据IFR的阻燃机理、三嗪成炭剂的结构特征和绿色化学的基本原则，设计了一种新型的绿色三嗪成炭剂-多羟基改性蜜胺树脂及其绿色合成路线。该成炭剂是通过将传统成炭剂-多元醇接枝到三聚氰胺甲醛树脂上而制得的。本项目拟合成一系列多羟基改性蜜胺树脂，并通过系统评价它们的阻燃作用，将从中筛选出几种高效的绿色成炭剂。通过鉴定热分解产物和燃烧残余物的结构及组成，并结合理论分析，研究它们的作用机理。采用线性回归方法建立它们的定量构效关系模型。在此基础上，构建一种高效绿色成炭剂的分子设计新思路，以便为今后研究更高效的绿色成炭剂提供理论指导。

膨胀型阻燃剂（IFR）是一种具有发展潜力的绿色阻燃剂，而成炭剂是其关键物质之一。大分子三嗪成炭剂是目前广泛使用的成炭剂，但它存在合成过程中环境污染及安全隐患严重等问题。为此，本项目设计了一种新型的大分子三嗪成炭剂-多羟基改性密胺树脂(简称改性树脂)。采用固相合成法，分别通过季戊四醇、乙二醇、丙二醇、一缩乙二醇、二缩乙二醇、甘油，赛克和三羟甲基丙烷等与三聚氰胺甲醛树脂醚化和缩合合成了9种改性树脂。通过详细评价它们的热稳定性和阻燃作用，筛选出三种理想的成炭剂，即季戊四醇改性树脂、赛克改性树脂及季戊四醇和赛克混合改性树脂。它们与聚磷酸铵（APP）复合而成的IFR对聚丙烯（PP）具有良好的阻燃作用，如当混合改性树脂和APP的质量比为1:3，改性树脂/APP的添加量为26%时，阻燃PP（3.2mm厚）能通过UL 94 V-0级。该IFR还能显著抑制PP的裂解和燃烧火焰的传播而降低火灾的危险性。揭示了多元醇类型及其接枝度对成炭剂性能影响的规律。改性树脂的阻燃作用略差于市售的三嗪成炭剂，但其合成过程中环境污染小及基本无安全隐患。详细研究了改性树脂/APP的阻燃作用机理。与其它的IFR一样，改性树脂/APP也主要是通过凝聚相产生阻燃作用。在燃烧过程中，改性树脂及其裂解产物先和APP的裂解产物反应形成磷酸酯或磷酰胺。当这些产物处于熔融状态时，改性树脂和APP裂解出的惰性气体使它们发泡，随后APP裂解成的聚偏磷酸使它们脱水成炭，炭和聚偏磷酸交织在一起，形成结构致密及强度良好的膨胀炭层。该炭层通过隔热、隔氧而阻止基材进一步裂解及裂解产物的挥发而产生阻燃作用。在此基础上进一步研究了改性树脂/APP与沸石及硅质矿物（如膨润土、海泡石等）对PP的协效阻燃作用及机理。以上成果对今后研究更加高效的成炭剂及IFR具有重要的指导作用，开发出的成炭剂也具有重要的工业应用价值。