What is Vulcanized Fibre?

“Invention for (an) improved means of giving increased strength to paper.” This was the introduction of a patent application in 1859 by Thomas Taylor for the vulcanized fibre process. This patent was the procedure for converting a cellulose paper material into a unique laminate product with an unusual combination of “plastic-like” physical and chemical properties. Paper was transformed into a material that possessed increased strength and durability.

VF is a laminate of cellulose paper plies. The raw material is 100% rag cotton cellulose or wood pulp cellulose which is then manufactured into an unsized, saturating grade paper. The cotton cellulose fibers are recycled waste cuttings from textile mills. The wood pulp cellulose is a high alpha pulp. Recycled paper and secondary fibres can be used for some applications. The paper is saturated with a concentrated zinc chloride solution. The zinc chloride is a catalyst that is not consumed in the process. The saturated paper plied then bond together.

The zinc chloride is removed from the web through a series of water leaching tanks until the web has exchanged the zinc chloride with water to a purity of 0.05%. The zinc chloride is completely recycled through a recovery process.

The web structure that is now saturated with water after puring process is then dried to a moisture content of 5–8%. It is during this drying step that the unique properties develop. The density of the product increases 2-3 times as the result of shrinkage – 10% in the machine direction, 20% in the cross direction, and 30% in the thickness. The final product is 100% cellulose.

Electrical Insulation Conference
Cincinnati, Ohio, USA
Oct, 1999

Abrasive Fibre Specifications

ThicknessRangeDensityMoistureTensile
Strength
(MD)
Tensile
Strength
(CD)
Ratio of
Tensile
Strength
mmmmg/cm3%N/15mmN/15mm
0.60.58-0.62>= 1.226.5 - 8.5>= 1000>= 600>= 0.55
0.70.68-0.72>= 1.246.5 - 8.5>= 1100>= 700>= 0.60
0.80.78-0.82>= 1.256.5 - 8.5>= 1250>= 750>= 0.60

Electrical Insulation Fibre Specifications

ThicknessDensityDielectric
Strength
MoistureTensile
Strength
(MD)
Tensile
Strength
(CD)
Chlorine
Content
mmg/cm3kV/mm%N/15mmN/15mm%
0.5>= 1.1013 - 176 - 9>= 1000>= 600<= 0.05
0.6>= 1.1015 - 186 - 9>= 1100>= 700<= 0.05
0.8>= 1.1013 - 186 - 9>= 1250>= 750<= 0.05
1.0>= 1.2010 - 207 - 10>= 1250>= 750<= 0.05
1.2>= 1.2011 - 187 - 10>= 1250>= 750<= 0.05
2.0>= 1.208 - 157 - 10>= 1250>= 750<= 0.05
2.4>= 1.207 - 157 - 10>= 1250>= 750<= 0.05