What's the heat resistance and melting point of optical brighteners?

The melting point is the temperature at which the solid and liquid states of a pure substance are in equilibrium under a certain pressure.In simple terms,melting point is a solid changes its state from a solid state melts to a liquid state.

Heat resistance refers to the property that a substance can still maintain its excellent physical and mechanical properties under heated conditions.

For optical brightener ，melting point is a very important test indicator，but most people confused it with heat resistance.For example optical brightener MDAC,also name fluorescent brightener SWN,its C.I. NO:140,and its CAS NO.is 91-44-1, optical brightener agent MDAC can be used for PVC and wool.

As we all know ,the melting point of optical brightener agent MDAC is 70℃,but its heat resistance is different.

When optical brightener agent MDAC/SWN used for PVC,its heat resistance is 170℃,while when used for wool, its heat resistance is 50℃.

So even we see optical brightener OB-1's melting point is 360℃,but not say it can work when production reach 360℃.

For other optical brighteners are the same situation.Different optical brighteners used for different materials have different heat resistance.

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