Textile based heat-bonding products are now widely used in the clothing industry and make it possible for example to manufacture linings or reinforcement fabrics which can be heat sealed.
A number of methods and apparatus for manufacturing such products by coating are known.
A first category of methods, called HOT MELT methods, consists in directly applying a molten thermoplastic polymer mass on the textile supporting base. For example, for implementing this method, a polymer mass is brought to a temperature higher than its melting temperature, it is distributed in the cavities of a photogravure cylinder (hollow engraved), the surface of this cylinder is scraped and it is placed in contact with the textile supporting base on which the polymer spots are to be applied.
These methods have a number of drawbacks which have prevented them up to now from developing despite the advantages which they offer.
In fact, this method does not make it possible to obtain quality spot coating. The action of the scraper does not completely eliminate the traces of polymer on the smooth surfaces of the cylinder. Hot polymer residues remain on these surfaces and come into contact with the textile base. In some cases, the textile supporting base, in contact with the photogravure cylinder, loses fibres which adhere to the cylinder, contribute to its clogging up and may even deflect the scraper from the cylinder which produces a continuous adhesive polymer layer which is then deposited on the textile base. The quality of the product obtained is low and ill suited to use in the clothing field.
During use of this method, the polymer mass contained in the cavities, when placed in contact with the textile supporting base, adheres thereto, which contributes to emptying the cavities and depositing of the spots on the textile base. Aerated textiles, or those with gaps or empty spaces, do not provide uniform adherence of the polymer contained in all the cavities. Some of them are then not suitably emptied which leads to coating defects.
A method is further known of manufacturing thermoadhesive textile products in which the adhesive is deposited on the textile base in the form of spots of powder or of aqueous solution. After such deposition, the whole is brought to a high temperature which melts the polymer and causes it to adhere to the textile base.
The patent FR 2 586 717 describes a method of this latter type in which drops of a heat-bonding material dispersion are first of all deposited on an anti-adhesive transfer base; then the drops on the transfer base are heated and the drops of adhesive are placed in contact with the textile base.