摘要:磷腈類化合物的基本構造為一個磷以雙鍵與一個氮原子,和以單鍵與另外三個原子團或自由基以共
價鍵結合。這一類磷氮雙鍵化合物因為在難燃性方面的協合效應,所以與其他的難燃劑,如DOPO 和
melamine/磷酸鹽等等,在工業用途上極為重要。在過去五十年,多數研究皆著重於合成具有更佳難燃
性之磷腈衍生物的方面,但是大部份都是針對摻混磷型腈類化合物於各種高分子材料中,如高分子彈
性體。雖然此物理摻混方法在研究結果中顯示在難燃性上有所提升,但作為添加劑,其所需的高混摻
用量會造成材料機械物性下降,以及在商品化的可行性上也較不具有經濟方面的考量。
在另一方面,有少數幾個研究則致力於反應性的磷腈類來增進它們與目標高分子間的相容性,但是
因為磷腈化合物具多官能基的特性,這些新衍生物只能做為架橋劑或者是用在環氧樹脂等類的交聯系
統。於其他應用上,尤其對於熱可塑性材料的處理與回收是莫大的困擾。可數的幾個研究專注在雙官
能基反應型磷腈化合物,目前的進度尚停留在學術層面且較不具有商業價值,所以如果能合成一系列
的雙官能基反應型的磷腈衍生物,能在後續難燃用途的添加上更便利於摻混和加工,對磷腈類化學而
言將是一大突破。
在此研究計劃裡,第一年將以六氯環三磷腈(hexachlorophosphazene or HCP)為起始原料,它可以從
一個可信賴的供應來源取得。在四個氯原子被不具反應性的脂肪族或是芳香族基團,如酚,取代後,
剩餘的二個氯再以雙官能基的化合物,如雙羥,胺醇,雙胺取代。尤其是以Jeffamine® amine 的取代
最為重要,因它可以增進磷腈分子在高分子間的分散性,並有助於往後延伸的性質提升之研究。此反
應的第一步將會著重在以各種具有官能基的化合物將六氯環磷腈部份的氯原子反應,包括酚類(甲
酚,鄰苯二酚,雙酚-A 等)和芳香族胺類(苯胺,萘胺等)對磷腈環上的氯的取代,這將有助於了解取
代反應的速率以及相對的反應性。故剩下雙反應點之環磷腈化合物將以Jeffamine® amine 合成一系列
具胺官能基且不會造成交聯效果的磷腈-胺產品。
第二年計畫中,此雙官能基的磷腈化合物將與奈米矽片以及其他的層狀黏土改質。藉由改質後的功
能性有機黏土,能更提升與高分子的相容性,並因為片狀結構的無機黏土具有大的表面積,使得磷腈
類在高分子材料中的添加量能降低。另外,這些合成的雙官能基磷腈衍生物,會與一些常用的高分子
主體以化學法結合來測試它們的熱安定性和難燃性。最後再提出實用並可以大量生產這些磷腈化合物
的工業流程。
在這個計劃案中,大多數的合成工作,包括磷腈衍生物,黏土插層,和以 TGA,IR,DSC 等等的
產品定性將會在台灣大學進行。包括使雙軸押出機來混鍊聚醯胺類,如尼龍-6,以及難燃性的測試將
會在合作企業晉倫公司進行。在計劃後期,量化流程將會嘗試使用設置在國慶化學的大型反應槽試
俥。我們預期,透過經常性的進度討論和交換分析結果等等能使三方面的合作更加密切。本研究計劃
的主要的成果之一也包括了申請通過至少一項關於材料組成的專利。一個可行性的研究與商業化的計
劃將會在這個二年研究計劃的結束時提出。在整體耐燃化合物之研發上,希望此控制”雙官能基的磷
腈化合物”與黏土插層方法製程可提供獨特貢獻。
Abstract: Phosphazenes are a class of chemical compounds in which a phosphorus atom is covalently linked to a
nitrogen atom by a double bond and to three other atoms or radicals by single bonds. This class of P=N compounds are known for their synergistic effect on the flame retardancy and hence have attracted much attention for industrial applications among other retardants such as DOPO and melamine/phosphate salts.
For the past fifty years, a great deal of efforts have been put into the synthesis of new phosphazene derivatives in order to find more promising derivatives and candidates as a flame retardant. Yet most of the studies were concentrated on blending the phosphazenes with materials such as polymeric elastomers.
Although the test results did show some improvements in the thermal stabilities, the heavy weight
percentage used as an additive would deteriorate the mechanical properties and reduce the economic
attractiveness for practical usage as commercial products.
A few studies, on the other hand, dealt with reactive type of phophazenes in order to improve their
compatibility for the targeted polymers. However, due to the mutli-functionality nature of the compound, the new derivatives could only be used as crosslinking agents or in the crosslinked systems such as epoxies.
This would present a devastating problem in the processing and recycling of thermal plastic materials. Very few researches were focused on difunctional, reactive type of phosphazenes. The progress thus far remained as of only literature importance and lacked of commercial value. Therefore, it would be a big breakthrough in phosphazene chemistry if one can synthesize a series of bifunctional and reactive type of phosphazene derivatives which allow a easy blending and processing in downstream applications for the fire retardant purposes.
In our research plan, we would begin by using hexachlorotricyclophosphazene (HCP) as the starting
material which is available from a reliable commercial source. As four of the chlorine atoms replaced by non-reactive alkyl or aromatic groups such as phenols, the remaining two chlorines are substituted by difunctional compounds, such as glycols, aminoalcohols, diamines, and especially Jeffamine amines, which would enhance the dispersion of the phosphazene moiety in the polymer matrix incorporated in the later stage of the research. The first-step substitution of the phosphozene chorides by different functional compounds including phenol types (cresol, catechol, bisphenol A etc.) and aromatic amines (aniline, naphalene amine, etc.) will be investigated. Particularly the reaction rate and relative reactivity of these substitutions will be understood. The second step involves the Jeffamine amine functionalization for achieve a series of non-crosslinkable phosphazene-amine products.
The difunctional phosphazenes are then modified with nano-silicate platelets and other layered clays.
This modification would further help the dispersion to an even greater extent since these platelets have very large surface area and thus allow lower percentage of phosphazenes needed in a polymeric material. At the later stages of the research, the synthesized difunctional phosphazene derivatives will be incorporated into various polymer backbones and tested for their thermal stability and flame retardant characteristics. Furthermore, feasible processes for the manufacturing of these phosphazenes on a commercial scale would also be proposed.
In this proposal, the most synthetic works including phosphazene derivatives, clay intercalation, product characterization by TGA, IR, DSC, etc., will be preformed in the NTU laboratories. The blending including twin-screw mixing with polyamides such as Nylon 6 and fire retardant tests will be done in the collaborative company, Chin-Lun Co. The scale-up process will be attempted by using a larger reactor situated in Kuo-Ching Chemicals in the end of this project. We anticipate a good collaboration among these mentioned institutions by a frequent discussion on the progress, exchanging the test results and so on. At least one patent application on material composition matter is expected as one of the major accomplishments from this research task. A feasibility study and commercialization plan will be made in the end of this two-year research project.