He aha ka moisture-cured polyurethane

He aha ka moisture-cured polyurethane

ʻO ka polyurethane i hoʻōla ʻia i ka wai ʻO ka polyurethane hoʻokahi ʻāpana i hoʻomaka ʻia kona hoʻōla ʻana i ka makū kaiapuni. ʻO ka polyurethane hiki ke hoʻomaʻemaʻe i ka wai ka nui o ka isocyanate-terminated pre-polymer. Hiki ke hoʻohana ʻia nā ʻano like ʻole o ka pre-polymer e hāʻawi i ka waiwai pono. No ka laʻana, hoʻohana ʻia nā polyols polyether i hoʻopau ʻia i ka isocyanate e hāʻawi i ka loli maikaʻi ma muli o ko lākou haʻahaʻa haʻahaʻa hoʻololi aniani. ʻO ka hui pū ʻana i ka ʻāpana palupalu, e like me ka polyether, a me ka ʻāpana paʻakikī, e like me ka polyurea, hāʻawi i ka paʻakikī maikaʻi a me ka maʻalahi o nā uhi. Eia kekahi, hoʻomalu ʻia nā waiwai e ke koho ʻana i nā ʻano isocyanates e hoʻohui pū me ka pre-polymer.

ʻElua ʻano nui o ka isocyanates ʻo ia ka isocyanate aromatic a me ka isocyanate aliphatic. He kiʻekiʻe ka hana hou ʻana o ka isocyanate aromatic. Eia nō naʻe, maikaʻi ʻole ka lōʻihi o waho a me ka discoloration koʻikoʻi. ʻO kekahi mau laʻana o nā isocyanates aromatic he toluene diisocyanate (TDI) a me 4,4'diphenylmethane diisocyanate (MDI). Ma ka ʻaoʻao ʻē aʻe, ʻo ka isocyanate aliphatic, e like me, isophorone diisocyanate (IPDI), hāʻawi maikaʻi loa i ka weatherability a kala like 'ole ka paa ana; akā naʻe, haʻahaʻa ka reactivity o aliphatic isocyanate, no laila pono paha kekahi mau catalysts. No laila, he mea nui nā ʻano isocyanate e hoʻokō i ka waiwai i makemake ʻia. Eia kekahi, hiki ke hoʻohui ʻia nā additives, solvents, pigments, etc. ma muli o ka noi. Eia nō naʻe, pono e hoʻomalu ʻia nā mea maka no nā polyurethanes i hoʻōla ʻia i ka wai ʻole i mea e loaʻa ai ke kūpaʻa mālama maikaʻi a me ka waiwai kiʻiʻoniʻoni.

ʻO ka pōmaikaʻi ʻē aʻe o polyurethane hiki ke ho'ōla ʻia ʻo ia kekahi ʻāpana. No laila, maʻalahi ka hoʻohana ʻana no ka mea ʻaʻohe pono o ka hoʻohuihui pono ʻana, ke hoʻohālikelike ʻia me nā ʻāpana ʻelua. Hoʻopili ʻia ka PU i hoʻōla ʻia e ka hopena o ka Isocyanate-terminated pre-polymer a me ka wai i ka lewa, e hana ana i nā amine a me ka liʻiliʻi o ka carbon dioxide. ʻO ka hopena, ʻo ka hopena o nā amine a me ke koena o ka isocyanate-terminated pre-polymer e hana ʻia, e hana i ka pilina urea.