Rheology

Rheology means flow behavior. Rheology is the change in form and the flow of matter, embracing elasticity, viscosity, and plasticity. Generally, viscosity is the internal friction of the liquid coating caused by molecular attraction forces which makes it resist the tendency to flow. The greater the friction, the greater the amount of force required to cause movement. This movement is called shear. When the shear stress doesn’t vary in the same proportion, the coating is called non-Newtonian. Also, the coating system displays a decreasing viscosity with an increasing shear rate to be classified as pseudo plastic. The temperature is a major factor that has an effect on the rheological behavior of the coating. The addition of solvent and additives helped to control the rheology and the final appearance of the coating.

Rheology control of the viscosity is balanced through a polyurethane responsive material. The polyurethane thickening compound in glycol/water does show a rise in viscosity at increasing shear rates. The flow and leveling properties are enhanced at low shear. This agent exhibits good pH stability to the system. Stability to microbiological degradation is supported. The slight increase of the thixotropy is a complimented affect. The moderate thixotropic characteristics are non-Newtonian pseudo plastic.

A surface tension agent for flow and leveling lowers the surface tension for a uniform wet film. The chemistry of the tetra methyl decyne diol completes the effect of the leveling of the surface.

An oil/water adhesion enhancer for various plastic substrates assists for optimum performance properties. The adhesive bonding of the film to the substrate initiates as the coalescence begins.

Preservatives prevent bacterial and fungal growth in the package container, and also on the surface of the cured, dry film. Otherwise, formation of the mixed bacteria and molds initiate. The protective colloids in the aqueous phase can support growth of a wide variety of microorganisms.

A biocide gives prevention against mixed bacteria and mixed molds, which gives good in-car protection. A rapid micro-biocidal effect gives strong resistance from the following:

Mixed Bacteria

  • P.Aeruginosa
  • E.Coli
  • KI. Pneumoniae
  • S.Entiritidis
  • S.Epidermidis
  • S.Aureus
  • P.Putida
  • P.Cepacia
  • P.Vulgaris
  • P.Mirabilis
  • M.Luteus

Mixed Moulds

  • A.Niger
  • P.Purpurogenum
  • A.Alternata
  • CI.Herbarum
  • Rhodotolura.sp

A fungicide gives protection against fungi and algae, which gives good dry film protection. Good fungal/algal protection is given from the following:

Fungi

  • Aspergillus Niger
  • Penicillium Purpurogenum
  • Cladosporium Herbarum

Algae

  • Clorella Emersonli
  • Pleurococcus sp
  • Nostoc Muscorum
  • Oscillatoria Tenius
  • Stichococcus Bacillaria
  • Trentepholia Aureua