Polyurethane casting cov ntaub ntawv feem ntau muaj peb yam tseem ceeb: polyol, isocyanate, thiab additives. Kev xaiv ntawm cov khoom sib txawv ncaj qha txiav txim siab qhov ua tau zoo ntawm cov khoom kawg.
Polyol yog qhov tseem ceeb hauv kev txiav txim siab cov khoom siv tau yooj yim thiab elasticity, thiab feem ntau muab faib ua polyether polyols thiab polyester polyols. Polyether systems muaj kev ua haujlwm zoo hydrolysis, thaum lub tshuab polyester muaj zog dua txhua yam thiab kev puas tsuaj.
Cov isocyanates feem ntau suav nrog MDI (4,4'-diphenylmethane diisocyanate) thiab TDI (toluene diisocyanate). MDI systems muaj kev ruaj khov thiab muaj kev nyab xeeb dua, haum rau cov khoom lag luam casting, thaum TDI feem ntau yog siv rau hauv cov ntaub ntawv ua npuas ncauj.
Cov additives muaj xws li catalysts, chain extenders, crosslinking agents, defoamers, thiab colorants. Catalysts tswj cov tshuaj tiv thaiv tus nqi, saw extenders (xws li MOCA) txiav txim siab hardness thiab lub zog, thiab defoamers yog siv los txo cov npuas tsis xws luag.
Hauv kev tsim qauv, nws yog ib qho tsim nyog kom sib npaug hardness, elasticity, abrasion tsis kam, thiab kev ua tau zoo raws li cov khoom npaj siv. Piv txwv li, siab- cov menyuam abrasion feem ntau siv cov qauv siab- hardness, thaum lub cushioning pads yuav tsum qis dua hardness thiab ntau dua resilience.