Daffodil International University
Faculty of Engineering => Textile Engineering => Topic started by: nawshin farzana on July 18, 2014, 05:25:20 AM
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Flock print
The flocking process involves applying short monofilaments fibres, usually nylon, rayon or polyester, directly on to a substrate that has been previously coated with an adhesive. This print type is suitable for almost all fabric types and due to its fluffy velvet-like surface, looks and feels amazing. Flock print feels great and a bit elevated. It looks soft but is actually quite durable and does not fade. Flock retains its colours long throughout a life of regular washing at 40°C. Ironed inside out, machine drying is fine on it.
There are two types of flock -- milled and cut. Milled flock is produced from cotton or synthetic textile material. Because of the manufacturing process milled flock is not uniform in length.
Adhesives
Adhesives create most favourable effect on the quality of flocking. They make the link between the flock and the substrate. They are preferred to be soft, flexible and washproof. Today acrylate-based dispersions are significantly applied for special application, like waterproof jackets or other coated fabrics; solutions can be applied as well. Dispersion glues are distinguished between low and high temperature curing glues. At room temperature curing within two to five days, the low temperature glue dries. This denotes, after this time has passed the garment can be washed. A fixing agent has to be applied for curing. It is critical to understand the producer's instructions concerning the mixing ratio and blend the fixing agent homogeneously into the glue.
The adhesive is applied to the substrate by screen-printing. Normally, we apply a screen mesh prepared by polyester as it absorbs only less water and does not covered by the dispersion glue and in cleaning. Screen meshes of 24 T to 40 T are applied (standing for 24 to 40 threads per cm²) as the adhesive layer is comparatively thick. In against ordinary screen-printing these meshes are proved to be relatively rough, but the glues are paste likes up to thixotropic, and enough amount has to be used on the substrates.
Heat applied flock printing
Heat-applied flock print is popular for large front or back designs to give the garment a more quality appearance.
This process can be applied to:
º Polo shirts
º T-shirts
º Sweatshirts
º Fleece
º Caps
º Cotton, Polyester, Poly/Cotton Garments
multi-colour flocking
The methods are mentioned as below:
º Multiple flocking
º Cover-up flocking
º Iris flock
º Flock-on-flock
transfer flock
In this process the idea is to iron flocked logos on a fabric piece and is similar to transfer printing. There are many possibilities to do the same. The easy form is to flock hot-melt foils and punch out letters or logos, which are afterward ironed onto the fabric. Though this process needs costly punching tools, only larger batches of a logo can be done. The process is generally applied for the manufacturing of letters, digits and firms' logos.
Reverse method, single colour
In this process a special transfer flock paper is used, where the flock is fixed in a simply detachable way. A mirror image of the design is made with the adhesive. After that hot-melt powder is applied over the adhesive when it is wet. After it becomes dry, the design is over-turned, ie, it is put on the fabric with its hot-melt powder side onto the fabric and is afterward ironed on. The hot-melt powder mixes with the fabric, and in the part where the adhesive was imprinted the flock releases from the mover material.
Reverse method, multi-colour
This process is similar to the reverse method; single colour but here needs a transfer paper of simple white one. In this process, first the colours of the design are embossed, and then the adhesive with the hot-melt powder is applied. It is essential that the printing ink actually enter the flock. Delicate greyness on the finished transfer will make deprived quality