Flexible PVC

Flexible PVC is polyvinyl chloride resin that has absorbed plasticizer (mostly phthalates) to achieve desired properties such as hardness, tensile, elongation, and high brittle point.

After achieving fusion, the PVC resin/plasticizer is of uniform strength, with the plasticizer interspersed uniformly between the polymer chains to the extent that secondary forces are built or formed that allows the mixture to become a permanent mass of high physical strength.

Flexible PVC is compounded with many other ingredients necessary for processing and physical properties. First and foremost, a heat stabilizer must be chosen. Other important additives are colored pigments, lubricants, fillers, protective agents, pesticides and biocides, and impact modifiers.

TiO₂ is included in the formulation to achieve desired properties such as high whiteness, hiding power, chemical stability, and weatherability. It is important to select the correct TiO₂ grade to maximize dispersion, optics, and weatherability.

Calendered PVC: To produce highly accurate films and sheets from PVC at a large volume, one would use the calendering process. Web thickness ranges of 0.08 – 0.8 mm can be achieved by applying pressure between two or more counter-rotating rolls. The designs of modern calender trains are similar for both rigid and flexible PVC and the choice of TiO₂ is dependent on the desired properties.

For applications where maximum dispersion is desired, a general purpose or high performance TiO₂ are recommended.

For maximum weatherability, a durable TiO₂ product will ensure low chalking and maximum color hold. To maximize the UV absorption/stabilizing effects of TiO₂ pigment, sometimes loading levels of up to 10% are desirable. Even at these levels physical properties are mainly unaffected.

Plastisols: Plastisols are liquid dispersions of special PVC resins in liquid plasticizers. Stabilizers, pigments, filler, diluents, and foaming agents are also common compounding ingredients. Since plastisols are processed in liquid form, viscosity is one of the most important properties.

The choice of TiO₂ is dependent on its dispersion in the plastisol and also its affect on viscosity. General purpose or high performance TiO₂ are highly recommended in plastisols because of their consistent particle size, particle size distribution, and surface treatment application that ensures consistent dispersion and oil absorption.

For maximum weatherability, durable TiO₂ will ensure low chalking and maximum color hold. To maximize the UV absorption/stabilizing effects of TiO₂ pigment, sometimes loading levels of up to 10% are desirable. Even at these levels physical properties are mainly unaffected.