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指導教授 : 王振乾教授 研究生 : 符昌中

指導教授 : 王振乾教授 研究生 : 符昌中. Introduction. 異氰酸酯 (isocyanates) 具有 (-NH-CO-O-) 官能基與末端為 羥基 的寡聚物能快速反應形成聚氨酯，因此 異氰酸酯儲存不易 。 為解決儲存問題，利用封閉劑將異氰酸酯官能能封閉，在硬化的過程中經由 加熱解封閉 與羥基反應。 封閉劑的特性是在一定溫度範圍內產生 解封閉反應 。. Introduction. 在解封閉的過程中，封閉劑的揮發會導致 空氣汙染 ，或最後殘留在高分子中作為 塑化劑 。

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指導教授 : 王振乾教授 研究生 : 符昌中

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  1. 指導教授:王振乾教授 研究生:符昌中

  2. Introduction • 異氰酸酯(isocyanates)具有(-NH-CO-O-)官能基與末端為羥基的寡聚物能快速反應形成聚氨酯，因此異氰酸酯儲存不易。 • 為解決儲存問題，利用封閉劑將異氰酸酯官能能封閉，在硬化的過程中經由加熱解封閉與羥基反應。 • 封閉劑的特性是在一定溫度範圍內產生解封閉反應。

  3. Introduction • 在解封閉的過程中，封閉劑的揮發會導致空氣汙染，或最後殘留在高分子中作為塑化劑。 • 本實驗合成新的封閉劑2-formyloxyethyl methacrylate(室溫下為液態，解封閉溫度為110℃)，研究溫度和解封閉反應動力學。

  4. Materials • 2-Hydroxyethyl methacrylate (HEMA) • 1,6-hexanediol • 4,4'-diisocyanate diphenylmethane (MDI) • Isophorone diisocyanate(IPDI-Desmodur I) • hydroxyl terminated polyether(Desmophen 1900 u) fn=1.58 and Mn=1729 g mol-1

  5. Synthesis 2-Formyloxyethyl methacrylate (FEMA) synthesis + Formic acid cyclohexane + + + Hydroquinone HEMA The mixture was refluxed for one day. Cyclohexane and formic acid were distilled under reduced pressure. The ester under liquid state was purified by column chromatography using a 50:50 (v:v) mixture of diethyl ether and petroleum ether. Dean and Stark apparatus

  6. Synthesis Blocking reaction Unblocking reaction 2-Formyloxyethyl methacrylate Blocked isocyanate in the presence of ethylbenzene was put between two KBr pellets and the deblocked isocyanate groups were quantified by FTIR at 908C. 2hr diisocyanate dibutyltin dilaurate ethyl benzene

  7. Synthesis Polycondensation of blocked isocyanate with 1,6-hexanediol and with a dihydroxy terminated polyether 1,6-Hexanediol blocked isocyanate at 80℃ Polyether 1900 u

  8. Results and discussion 3 5,6 7 1 1 1H-NMR spectrum of 2-formyloxyethyl methacrylate. d(ppm): H1: 5.6 and 6, H3: 1.9, H5 and H6: 4.4, H7: 8.2, cyclohexane:1.4.

  9. Results and discussion 1 6 5 3 7 2 4 13C-NMR spectrum of 2-formyloxyethyl methacrylate. d(ppm): C1: 125, C2: 135, C3: 18, C4: 166, C5 and C6: 61 and 62, C7:161, cyclohexane: 25.

  10. Results and discussion 7 8 13C-NMR spectrum of blocked MDI by 2-formyloxyethyl methacrylate in DMSO d6. d(ppm): C7 and C8: 161 and 197, C4:166

  11. Results and discussion (A2272/A1689)t and (A2272/A1689)0 are the ratio of isocyanate absorbance(ν NCO = 2272 cm-1) to the reference absorbance (ν C=O acrylate =1689 cm-1) at time t and 0. The isocyanate conversion of IPDI stabilises at a level of 80%. Probably, IPDI could be entirely blocked at higher temperature and in the presence of a greater quantity of catalyst. Blocking kinetics by FTIR at room temperature. (a)4,4'-MDI/FEMA (b) IPDI/FEMA.

  12. Results and discussion MDI presents an advantage with respect to IPDI, i.e. it blocks and unblocks at lower temperatures than IPDI does. DSC thermogramms. (a) 4,4'-MDI/FEMA (b) IPDI/FEMA.(5~15 mg)

  13. Results and discussion These free NCO groups react immediately once more with the labile hydrogen of formyl groups (second blocking reaction), effectively an increasing XNCO succeeds its decrease. Unblocking kinetics by FTIR at 90 ℃ of (a) blocked MDI and(b) blocked IPDI.

  14. Results and discussion (δOH =1060 cm-1 and δCH =1452 cm-1 reference peak Simultaneous unblocking and polycondensation kinetics by FTIR: (a) blocked MDI with 1,6-hexanediol; (b)blocked MDI with polyether; (c) blocked IPDI with 1,6-hexanediol; (d) blocked IPDI with polyether.

  15. Conclusions • 成功的合成出新的封閉劑2-Formyloxyethyl methacrylate，且封閉反應在室溫下能快速進行。 • 封閉型聚氨酯與多元醇的聚縮合反應，因解封閉快，在設定的溫度下能簡單的反應。

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