Production process of PVC coated canvas

Introduction

PVC coated canvas cleverly combines the flexibility of textiles with the protective properties of plastics. So how does an ordinary piece of cloth "put on" this tough plastic? Let's unveil the production process of PVC coated canvas.

1. Material preparation

The selection and treatment of the base fabric determines the ultimate strength and stability of the canvas. Common base fabrics include:

Polyester canvas: High strength, wear resistance, stretch resistance, dimensional stability, and not easy to mildew, it is the current mainstream choice.

Nylon canvas: Extremely high strength, good elasticity, excellent wear resistance, but high cost, and the size may change slightly after moisture absorption.

Cotton canvas: Good feel and environmentally friendly, but relatively low strength, easy to absorb water and mildew, and is rarely used in applications that require high strength or long-term waterproofing.

The base fabric must be strictly treated before coating, and the oil, wax, and impurities left over from the spinning and weaving process must be cleaned and removed; sometimes a thin layer of adhesive must be applied to enhance the adhesion of the PVC coating to the fabric to prevent it from falling off in the future.

The formulation of PVC paste resin is the key. The main raw material is extremely fine PVC powder (paste resin), which needs to be fully mixed with a variety of additives in a large mixing tank to form a uniform and viscous paste. Plasticizers directly determine the softness and hardness of the final canvas.

Stabilizers prevent PVC from decomposing and discoloring during subsequent high-temperature processing and use. Flame retardants and anti-UV agents can improve fire resistance or weather resistance.

2. Coating

Coating is the core link of the entire process, and there are two main mainstream technologies:

Knife coating method:

The base fabric passes smoothly through the coating table under the traction of the guide roller.

The prepared PVC paste is conveyed to the top of the base fabric.

A precision scraper is suspended above the base fabric, and the gap between the blade and the base fabric is precisely controlled. When the base fabric passes under the knife, the excess paste is scraped off by the scraper, leaving a uniform and thickness-controlled layer of PVC paste attached to the fabric.

Calendering method:

The PVC material that has been plasticized by high-temperature mixing is fed between a set of heated giant rollers (calendering rollers).

The base fabric is introduced between the calendering rollers.

Under high temperature and pressure, the softened PVC is strongly calendered into a film and tightly bonded to the base fabric.

3. High-temperature melting

The fabric coated with PVC paste cannot be used directly. At this time, the PVC is only attached in a paste state and has poor physical properties. It needs to go through a critical plasticization process:

The coated wet material enters a long, multi-temperature oven (plasticizing furnace).

Bake at a precisely controlled high temperature (usually 180-220°C) for a certain period of time.

The high temperature causes the PVC particles to melt and plasticize thoroughly, and the plasticizer is fully integrated with the PVC molecules.

At the same time, physical and chemical reactions occur inside the PVC coating and between it and the base fabric, forming a dense, tough, elastic continuous plastic layer, which is strongly bonded to the base fabric.

The plasticization process is crucial to the physical and mechanical properties (strength, peeling force), weather resistance, feel, etc. of the final product.

4. Finishing and shaping

After high-temperature plasticization, the material needs to be cooled and shaped. The hot canvas is quickly cooled by the cooling roller (with cooling water inside), so that the molten PVC layer solidifies and shapes, and keeps it flat. According to the needs, the cooled canvas may be pressed out with specific patterns by the embossing roller to increase the surface friction, aesthetics and anti-adhesion.

Finally, the cooled and shaped PVC coated canvas is neatly rolled into a large roll, waiting for subsequent cutting and sewing into the final product.

Conclusion

The production of PVC coated canvas is a journey of precise material integration. From carefully selected raw materials, to scientifically formulated coating formulas, to precisely controlled coating, high-temperature plasticization and cooling shaping processes, each step embodies the wisdom of material science and engineering technology. PVC canvas is known for its waterproof, mildew-proof, flame-retardant, wear-resistant, anti-aging and easy cleaning. It is an indispensable protective material in industry, agriculture, construction, transportation, and even daily life.