The chemicals for the paper industry fall into bulk commodities used in pulping and bleaching, and specialty chemicals added at the wet end and in coating. India makes a wide share of both, with Gujarat strong in the basic chemicals. Supply should still be qualified on your own machine.
The basic chemicals link to what basic chemicals Gujarat produces.
Which chemicals do paper mills use?
- Pulping and bleaching: caustic soda, sodium sulphate, sodium sulphite, hydrogen peroxide and chlorine dioxide inputs, sold to a stated strength and purity.
- Wet-end additives: alum or polyaluminium chloride for pH and fixing, cationic starch for strength, and retention and drainage aids.
- Sizing agents such as rosin size, alkyl ketene dimer and alkenyl succinic anhydride, which control water resistance.
- Optical brightening agents and dyes for whiteness and shade.
- Fillers and coating components such as calcium carbonate, kaolin, talc, binders and rheology modifiers.
- Process chemicals: defoamers, biocides, and boil-out and cleaning products.
What should a mill qualify before approving a supplier?
Specifications on paper do not predict machine behaviour, so qualify with a trial. The properties to track depend on the product. Our guide to testing specialty chemical performance covers how to set up a fair comparison against your present product.
- For caustic soda and bulk chemicals: concentration, iron and chloride or sulphate content, and consistency between lots.
- For starch: degree of cationisation, viscosity and solids, because they affect strength and retention.
- For sizing: the degree of sizing achieved, usually checked by the water absorption test, at a set dose.
- For brighteners: whiteness gain and stability, assessed with brightness measurements.
- For all additives: foaming, deposit formation and effect on retention and runnability on the machine.
What about food-contact and regulation?
If the paper will touch food, such as cups, bags and packaging, the additives must meet food-contact rules in the destination market. Different regions use different positive lists and recommendations, so give your supplier the target market and ask for the relevant declarations.
Hazardous bulk items such as caustic soda and hydrogen peroxide are dangerous goods in transport and need correct packaging, labels and documents. Rely on your shipper and broker to confirm.
How to source
Buy from a manufacturer that can show batch records, keep a second approved source for each critical product and agree a specification in the contract. The wider list of what the state makes is in specialty chemicals made in Gujarat.
Mills run continuously, so late or off-specification material costs production time. Ask the supplier for realistic lead times, packing that suits your handling, such as tankers, IBCs or bags, and a plan for stock at your site. For liquid chemicals, check that the tank or IBC was cleaned of previous contents, and test a sample on arrival before it goes to the process. Where the product feeds the wet end directly, supervise the first runs so any problem is found early and traced to its lot.
Next step
We find paper chemical suppliers, arrange machine-trial samples, have lots tested and supervise loading. For your mill, book a free sourcing review.