 In this article we will discuss applying foam to a carded dry web as a means of bonding the fibers together. Foam can also be applied to bonded nonwoven webs for applying finishes to the nonwoven. There are two main components needed to apply foam to a nonwoven web: (1) a foam generator to produce the foam and (2) a foam padder or bonder.
Foam Generator The bonding chemicals are mixed with water and delivered to a foam generator. The purpose of the generator is to introduce air into the liquid and generate a foam made of small, consistently sized bubbles. The guts of the generator is usually a spinning head covered with pins that shears and froths the liquid. Think of something similar to foamy shaving cream. Here is a link to a typical foam generator made by Hansa Mixer. This link to the generator sold by Autofoam is a good description. Foam Bonder There are two types of foam bonders used in nonwovens. One simply consists of two rolls that form a nip through which the nonwoven web passes. This is what you see in the picture above. The nip gap is adjustable to regulate the amount of foam applied. (Note, that in foaming, the amount of bonding chemical in the foam is also a variable as well as the blow ratio of the foam generator.) This type of padder is made by Trutzschler. Autofoam makes a different type of padder, but this video shows the foam being dispersed across the width of the padder. Another type of foam applicator is the type made by Gaston Systems. This type applies the foam under pressure and through a parabolic application head designed to equalize the amount of foam applied across the width of the head. Hansa Mixer makes a similar foam applicator. Here is the definition for this week | 
In the last newsletter we started looking at the chemical bonding of nonwovens. This newsletter continues as we consider using foam as a method of delivering the bonding chemicals to the dry nonwoven web. 
