Добрый день, господа
Просветите пожалуйста, как расчитывать правильно NCO/OH в органических 2K PU системах?
Есть система из 2-3х PU дисперсий и отвердитель + разбавитель (судя по документации подойдет в качестве разбавителя бутилацетат).
Есть целевой показать NCO/OH для системы, но стоит задача достичь определенных физ. свойств путем изменения пропорций 3х PU дисперсий.
Расчет NCO/OH
Re: Расчет NCO/OH
Нашел примерно такую теорию
Calculation required Isocyanate in Polyurethanes
When reacting an isocyanate in one or more polyols to form a polyurethane, one NCO group reacts with one OH group. When the number of NCO groups equuals the number of OH groups, you have a stoichiometric NC) : OH ratio of 1,0.
This ratio is commonly referred to as the index.
To determine the amount of isocyanate required to react with a given polyol blend, you must know the desired index (often 1), the isocyanate equivalent weight and the weight fractions (pbw) and equivalent weights of the polyols and any water present in the blend.
The following calculations give the stoichiometric ratio between grams of solid isocyanate resin and 100 grams of solid polyol resin.
By given OH % and NCO %:
(%OH / % NCO) x 247
% OH calculated from OH number = OH number/33
% OH calculated from OH eq.weight = 1700/OH eq.weight
OH number calculated from OH eq.weight = 56100/OH eq.weight
% NCO calculated from NCO eq.weight = 4200 / NCO eq.weight
Вот только не понятно почему 247 вылезло?
Calculation required Isocyanate in Polyurethanes
When reacting an isocyanate in one or more polyols to form a polyurethane, one NCO group reacts with one OH group. When the number of NCO groups equuals the number of OH groups, you have a stoichiometric NC) : OH ratio of 1,0.
This ratio is commonly referred to as the index.
To determine the amount of isocyanate required to react with a given polyol blend, you must know the desired index (often 1), the isocyanate equivalent weight and the weight fractions (pbw) and equivalent weights of the polyols and any water present in the blend.
The following calculations give the stoichiometric ratio between grams of solid isocyanate resin and 100 grams of solid polyol resin.
By given OH % and NCO %:
(%OH / % NCO) x 247
% OH calculated from OH number = OH number/33
% OH calculated from OH eq.weight = 1700/OH eq.weight
OH number calculated from OH eq.weight = 56100/OH eq.weight
% NCO calculated from NCO eq.weight = 4200 / NCO eq.weight
Вот только не понятно почему 247 вылезло?
Re: Расчет NCO/OH
Ну же, Тоник, цель близко.
Отто Георг Вильгельм Байер верит в Вас!
Отто Георг Вильгельм Байер верит в Вас!
Re: Расчет NCO/OH
В эквивалентах считать удобнее.
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