Nonwoven textile generally requires bonding either to itself or to another substrate. Typically, nonwovens are bonded to cloth, leather and other films for garments. The possible combinations and final product properties are tremendously large and encompass many industries. Some of the combinations are given below:

·Nonwoven with other nonwovens - surgical wrap and protective clothing; needle punched nonwovens with meltblown nonwovens for filtration applications
· Nonwovens with films- Dry-laid nonwoven/cellophane for battery separators
· Nonwovens with fibers- Meltblown/carded web such as 3M's Thinsulate for boots and outdoor garments
· Nonwovens with foams- Needle punched nonwoven/polyurethane foam/vinyl coatings for automotive landau tops
· Nonwovens witth extrusion coating- Needle punched nonwoven/vinyl coating for upholstery fabric

There are several methods of bonding nonwovens to the other substrates that are described above. Some of the most common methods of bonding are:
· Calendering - For perforation with solvent bonding
· Through air with emulsion adhesive
· Ultrasonic - with either thermoplastic or thermoset powder adhesives
· Dry bonding -with either film or fiber
· Dielectric - with hot melt bonding
· Powder Dot Process

Powder dot process is a bonding process where substrate is heated by means of a heated roller and at the same time is pressed against an engraved roller, which contains a thermoplastic powder. The second roller transfers the powder in a specific pattern onto the substrate. The paste dot coating system is generally considered to be a more flexible system than the powder dot coating system. It also provides minimum penetration (strike-through) and greater control in evenness of length and width of application. The paste dot process provides greater precision in the weight of the dot, shape of the dot, and the dot pattern.

There are a number of common applications for paste dot coatings. They can be applied to all sorts of textile products. The paste dot system is most effective when working with lightweight substrates such as nonwoven interlinings, which have a low tolerance to high temperatures. These end-uses include:
1. Fusible interlinings for woven, knitted, and nonwoven fabrics
2. Fusible dot coatings on breathable membranes (Goretex, Sympatex, Helsapor)
3. Print bonding on nonwovens
4. Anti-slip properties for automotive fabrics, tablecloth, etc.

The principle of the paste dot process is that thermo fusible pastes are applied directly onto the substrate by means of a rotary coater. The paste is pumped into a rotary screen and applied to the substrate by means of a squeegee. The treated substrate is then led through a drying tunnel so as to remove the water and any other volatile products.

The obvious advantage of using thermoplastic powders as adhesives is that true spot bonding can be achieved. By selection of particle size and applications means, it is possible to deposit discrete islands of binder, which will have the minimum restrictive effect on fiber mobility. As a consequence, fabrics with good strength and very soft handles can be manufactured. In this form of bonding, much of the adhesion is due to mechanical interlocking of fibers rather than to chemical bonding.

Of the various processes by which the paste dot adhesive can be applied, rotary screen printing is the most popular. It has surpassed the dry powder processes and ranks first among powder applications with about 60% of the total volume. In the rotary screen printing process, an aqueous suspension of finely divided thermoplastic powder adhesives and additives (the paste) is pressed through the holes of a rotating, perforated cylinder (the screen stencil) onto a cold web of fabric. This procedure is gentle to the substrates, and the wide range of options for formulating the paste gives the user flexibility in the application procedure. The rotary screen printing process is characterized by high and economical coating rates ranging between 30 and 60 m/min, and even upto 90 m/min in certain cases.
The internal adjustable doctor blade presses the paste through the holes of the stencil and onto the web of fabric, running over a counter-roller coated with hard or soft rubber. The viscosity of the paste can be adjusted to allow stencils of either coarse or fine screens to be used depending on the application and type of fabric. The internal The paste dots are then dried and circulating air or infrared radiations are next used to sinter the textile web.

Several manufacturers specialize in this type of applicator. On manufacturer supplies complete coating and laminating systems based on thermo fusible adhesives. Their equipment can be used to apply paste dots, and can also be designed for other processes such as powder dot, doubledot, and scatter coating.

Base resins in paste dot adhesive can be almost any thermoplastic. Frequently, polyamide or polyester copolymers are used for garment applications where wash-and-wear properties are required. Even dispersions of polyethylene in paraffin waxes are used to provide good flow properties and low melting points. Others include copolymers of ethylene with either acrylic acid or vinyl acetate.
The melting point of the paste dot adhesive is a significant parameter in this bonding process and will depend on the type, heat resistance, and ruggedness of the substrates. The base thermoplastics that are used in paste dot systems can have widely varying melting points. The paste has dual purposes as a carrier for the thermoplastic and to alter the melting range.
The primary components for a paste dot adhesive are the thermoplastic powder and the water matrix. Water is an inexpensive carrier, and it emits no volatile organic chemicals. The boiling point of water is generally close to the melting point of most hot melt powders. Additives, other than the water, that change the character of the paste dot include:
· Thickeners
· Dispersing and wetting agents
· Plasticizers
· Processing aids (running conditioners)
· Solvents and other viscosity-influencing substances.

There are several types of hot melt thermoplastics that can be used in formulating paste dot adhesives. Paste dot powders are generally ground to less than a 0-80 micron range, although slightly coarser powders can be used for special applications. The various types of thermoplastics have different melting points, and blends are used as well for even greater variation and range in melting point and melt viscosity.