SilMaterials in Paper & Pulp

Silicon Materials in Paper and Pulp

The paper and pulp industry consumes silicone materials primarily as defoamers and as release coatings on labels, tape backings, and food packaging. The industry is one of the largest single consumers of silicone defoamers globally because pulp digestion and paper-machine wet-end operations generate copious foam that must be controlled continuously.

Silicone Defoamers in Paper Manufacturing

Pulp digester defoaming: Kraft and sulfite pulping processes generate foam during cooking and brownstock washing. Silicone defoamers (50-500 ppm dose) prevent foam carryover into recovery boilers and washing equipment. Typical formulation: 5-25% silicone fluid (PDMS 100-1000 cSt) with 1-5% hydrophobic fumed silica spike, dispersed in oil or aqueous emulsion.

Paper-machine wet-end defoaming: 10-100 ppm silicone defoamer dose into the white-water system controls foam from surfactant residues and natural fiber fines. Without effective defoaming, foam blocks pumps, fouls felts, and creates surface defects in finished paper.

Coating-mix defoaming: paper-coating preparation involves high-shear dispersion of pigment and binder; silicone defoamers prevent air entrainment that would otherwise create coating defects.

Black-liquor evaporator defoaming: Kraft mill black-liquor concentration generates foam in multiple-effect evaporators; silicone defoamers prevent overflow that would shut down recovery.

The pulp and paper industry consumes 30,000-50,000 tonnes/year of silicone defoamer concentrate globally — making it one of the top three silicone application categories by volume.

Silicone Release Coatings

Pressure-sensitive adhesive (PSA) release liners: silicone-coated paper and PET film are the release liners for tapes, labels, and graphic films. Major chemistry: solvent-borne, water-borne, or solventless platinum-cured silicone systems coated at 0.5-2.0 g/m². Major suppliers: Dow Syl-Off, Wacker DEHESIVE, Shin-Etsu KS series.

Tape backing release: silicone-coated kraft paper and woven fabric backings for masking tape, packaging tape, and specialty tape products.

Food-packaging release: silicone-coated parchment paper and trays for bakery products and chocolate molding.

Label release: silicone-coated release liners support pressure-sensitive labels in product packaging across consumer goods.

Silicone Softeners for Tissue and Toilet Paper

Premium tissue and toilet-tissue products use silicone-based softening agents to provide the "soft hand" that consumers value. Typical chemistry: silicone-modified emulsion (amino-functional or polyether-modified silicone) sprayed onto the paper web at 0.05-0.5 wt% addition.

Specifications and Sourcing

Paper-industry silicone is largely commoditized:

• Silicone defoamer concentrate: 5-15 USD/kg, supplied by Dow, Wacker, Shin-Etsu, Lubrizol, BASF; substantial Chinese supply
• Silicone release coating: 8-20 USD/kg, technology-driven differentiation among major suppliers
• Tissue-softening silicone: 6-12 USD/kg, commodity chemistry with regional supply

For pulp and paper-machine defoaming, supplier selection is often based on application engineering support (the supplier's technical service team optimizes dosing and product formulation for specific mill conditions) rather than absolute cost.

Related Reading

Defoamer silicone oil grade, Release-agent silicone oil grade, Defoaming application, Mold release application.