Apparatus for making material with fusible backing

#This invention relates to the manufacture of material with a fusible backing in general and more particularly to an improved apparatus for making such fusible material using a dry printing process.

#Fusible interlinings are universally used in the manufacture of various articles of clothing. In general, such interlinings comprise a lining substrate, e.g., woven fabric, nonwoven, paper knitted fabric, etc., having polymeric material deposited thereon to permit the fusible interlining to be attached to the garment without the need for sewing by means of fusion through simultaneous heating, pressing or the like. Similarly, fusible backing is used in making iron-on patches and the like.

#Various methods have been developed in the prior art for making such fusible interlinings and the like, i.e. for applying the polymeric material to a substrate. Two general types of processes have been used. One is a random or scatter application of the polymer and the other method a discrete or controlled application. Most universally used is the random method in which a large number of particles are applied on a moving web. The polymer particles of a relatively large size are usually gravity fed from a feeder hopper located above the moving web which forms the substrate fabric. After being randomly coated with these particles, the web then passes under a heat source where the polymeric material is heated to its tackifying or melt point, after which it is calendered or pressed, cooled and then rolled up. The process is relatively simple and has been used to produce great quantities of fusible interlinings over the years. However, even with the development of highly usable polymeric materials such as polyamide, terpolymers, polyester polymers HDPE, urethanes, etc., the optimum application and functioning of a scatter product are limited because of the random laydown and the large particle size.

#FIG. 1 is a plan view of a fusible interlining manufactured using the prior art scatter process.

#FIG. 2 is a plan view of similar material treated using the process of the present invention.

#FIG. 3 is a schematic illustration of the processing apparatus of the present invention.

#For purposes of comparison the effect obtained with the commonly used scatter process of the prior art is illustrated by FIG. 1. As shown, a plurality of polymer particles 13 are deposited in random fashion on a substrate fabric 11. Through this random deposit there will be relatively large areas such as the area 15 containing no polymer, whereas in other areas such as area 17 the polymer particles may become more closely packed than is desirable and sometimes overlap. Thus, this prior art method does not obtain even coverage, introduces the disadvantageous agglomerate and does not obtain maximum benefit of uniform adhesive for the amount of polymer used. Large sized particles are necessarily used so that the falling polymeric particles remain on the substrate surface and not fall into the cross section of the substrate or completely thru. Thus, very fine particles in the 1-80 micron range are virtually not practical or applicable unless the substrate is opaque otherwise, if the 1-80 micron range is used, the substrate is usually so completely coated as to constitute a continuous film.

#The same substrate 11 treated with the printing process of the present invention is illustrated on FIG. 2. As indicated above, the process is carried out by maintaining the substrate in contact with a printing screen having supplied to its opposite side fine particles of polymer dust. The screen and substrate remain in contact long enough for the polymer dust to fill the openings in the screen and cover the full desired area on the substrate. Thereafter, the substrate is heated from below to bond the polymer to the substrate. The result, using a screen which have openings of hexagonal shape, is the deposit of polymer areas 19 is shown on FIG. 2. As illustrated, the areas where polymer is applied are evenly distributed and maximum utilization of the polymer is obtained.

#The finished fused dot is the result of several steps. The printed dot directly after printing and before fusing consists of many separate polymer particles. Upon heating the particles melt coalesce into a single large spherical dot due to the natural forces of cohesion and internal surface tensions. Therefor the shape of the unfused powder dot will generally be transformed into a sphere no matter what its dry state configuration. The shape of the screen openings are the result of the manufacturing method of screen preparation. i.e., the hexagonal shape is only an example of one particular screen.