Professional Polymer Technology
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As the temperature during the cleaning process is typic […]
As the temperature during the cleaning process is typically 130° to 150° C., the flame point or ignition temperature should be correspondingly high. On the other hand, compounds having a low molecular weight are preferred, since the consumption of substance is thus automatically reduced and favorable melting and solution characteristics of the reaction product are obtained.
Monohydroxyl polyethers are particularly suited as monohydroxy functional compounds since all of them have high flame points. The high molecular weight of these compounds, however, can be disadvantageous in some applications.
The use of abietyl alcohol as the monohydroxy functional compound in one-component cleaning compositions is preferred. For cleaning compositions consisting of a mixture including non reactive carriers, the use of methyl benzyl alcohol has proven to be particularly advantageous. Both monohydroxy functional compounds excellently meet the above-mentioned requirements.
To completely neutralize the moisture-reactive PUR hot melt adhesive, the cleaning composition is preferably used at an NCO:OH ratio of 1:1 with respect to the PUR hot melt adhesive to be removed. The content of NCO reactive compound in the cleaning composition can be favorably chosen such that the desired NCO:OH ratio corresponds to the mixing ratio of cleaning composition:hot melt adhesive.
In case, the cleaning composition may also contain resin, plasticizer, wax, non-NCO-reactive polymers and the like as additional components, e.g. to influence and adjust the viscosity and processing properties of the PUR adhesive compound.