Direct Coating - Production Process Overview.
Direct coated products are commonly called Tarpaulin PVC. The different qualities are measured and differentiated by their mass per square meter in grams (gsm).
The qualities we can manufacture in our direct coating process range from an 180gsm to 1100gsm. Our standard widths are 1.5m; 2.04m; 2.5m and 3m.
Direct coated products are manufactured by coating a liquid PVC paste directly onto the polyester basecloth. Different coating methods include dip-coating, knife over roll coating or airknife coating. Different layers contain different PVC formulations to give the desired quality. The coated basecloth then runs through the oven at about 200º C where it sets and becomes the solid, flexible PVC as we know it.
The PVC paste is mixed at Neucoat in our mixing department, here we mix a large number of different ingredients together. Different pastes for different products contain different ingredients (plasticizer, PVC, pigments, stabilisers and other additives) to give the final products their different desired qualities.
The basecloth is an integral part of a direct coated product; the tear and tensile strengths as well as most of the stability of the product is determined by the basecloth. Below is some detail to help you understand the properties of the basecloth (click diagram to enlarge view):
A yarn is made up of individual strands of polyester or filaments grouped together and sometimes twisted. The yarns come in a variety of sizes measured in DTex. The different thicknesses range from 280DTex to 2200DTex with the most common being 1100DTex.
The basecloth consists of threads of polyester running in two directions, the WARP, or ends (with machine direction), and WEFT, or picks (across machine direction) as indicated on the picture above.
For example: an 8 x 7.5 weave basecloth consists of 8 yarns per cm in the WARP direction and 7.5 yarns per cm in the WEFT direction.
A plain weave consists of single yarns in each direction only.
A full Panama (or Oxford) weave consists of two yarns running together in each direction, this gives extra tear strength. A half Panama weave has two yarns running together in one direction only; the yarn in the other direction is then a single yarn.