| 摘要 |
The present invention relates to a process and a device for uniform distribution of a free-flowing reaction mixture onto a continuously transported substrate over the desired width during production of foam webs. The distribution takes place towards the sides from a feed point by means of air. The simplest method of applying a foamable reaction mixture to a moving substrate is to centrally feed the mixture onto the substrate, which is generally a paper web carried on the conveyor belt, and to allow the reaction mixture simply to run outwards. The paper web prevents the reaction mixture from adhering to the conveyor belt. Generally, the film of reaction mixture which forms is of uneven thickness. The differences in thickness are compensated somewhat during foaming; however, the cell structure of the resultant foam is generally not uniform. Distribution rollers have therefore already been used. However, these can be employed economically only for the production of foam webs which have covering sheets on both sides to prevent the distribution rollers from contacting the reaction mixture. Since a bulge of reaction mixture must form in front of the distribution rollers, the residence times are relatively high. Attempts have been made (German Offenlegungschrift 1,778,951) to distribute the bulge more quickly towards the sides using air jets, in order to shorten the residence time. However, this measure is also unsatisfactory. The object of the present invention was to improve the distribution of the reaction mixture to thereby achieve a film of uniform thickness with a having a relatively short residence time. |
