Kraft paper is valued for its high strength and versatility, making it useful for packaging, industrial, and specialty applications. However, standard kraft paper has very little fire resistance. This drawback can be overcome through treatments that impart flame retardant properties to the paper. It provides protection against ignition and slows fire spread.

There are different methodologies to make kraft paper more fire resistant. Clay coatings containing alumina trihydrate or magnesium hydroxide can be applied to form a protective layer. These minerals release water upon heating, cooling the paper below combustion temperature. Chemical additives like ammonium phosphate can also be incorporated into the paper to disrupt the combustion process.

Some flame retardant kraft papers utilize additive-free approaches. For example, the pulping process can be optimized to yield higher lignin content in the fibers. Lignin chars when burned, decreasing flammability. Another additive-free method is siliconization, which loads nano-scale silica particles into the paper. The silica insulates the paper and dilutes available fuel.

Flame retardant treatments allow kraft paper to meet fire safety standards for applications like furniture backing, insulation facers, and automobile interior parts. The treatments do not overly degrade the paper’s strength or optical properties. This makes flame retardant kraft suitable when fire resistance as well as the durability and printability of kraft paper are required. With responsible chemical selection, it can retain kraft paper’s sustainability attributes. Flame retardant innovations safely expand kraft paper’s utility where fire is a risk.