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The application of silicone oil in the paper industry dates back to the mid-20th century. This semi-organic, semi-inorganic polymer compound, composed of silicon-oxygen bonds, has become a favorite in the paper industry due to its unique chemical properties. In the papermaking process, silicone oil is primarily used as a release agent, lubricant, and surface treatment agent.
In the wet-end process, silicone oil effectively reduces friction between fibers, allowing for more even distribution of pulp on the wire. When a 0.1%-0.5% concentration of silicone oil emulsion is added to the pulp, fiber dispersion can improve by over 30%, significantly reducing cloudiness and fiber clumps in the sheet. This effect is particularly crucial in producing high-grade cultural paper. Research data from a major Japanese paper mill shows that adding the right amount of silicone oil increases paper smoothness by 15% and noticeably improves printability.
In the drying section, silicone oil plays the role of a "liberator." When wet sheets with 60%-70% moisture content enter the drying section, they tend to stick to the dryer surfaces. A thin film of silicone oil (typically 0.1-1μm thick) applied to the dryer surfaces creates a barrier, allowing the dried sheets to peel off smoothly. Practical experience shows that proper use of silicone-based release agents can increase dryer temperatures by 5-10°C and boost drying efficiency by 8% without raising the risk of sticking.
Even more impressive is silicone oil's ability to impart special properties to paper. Paper treated with hydrogen-containing silicone oil can achieve water resistance ten times greater than untreated paper, making it highly valuable in packaging and specialty paper applications. A U.S. specialty paper manufacturer successfully developed electronic packaging paper with lasting antistatic properties using amino silicone oil treatment technology, increasing product value by 40%.
If silicone oil is the versatile performer, then defoamers are the "sedatives" of the papermaking process. In stages such as pulping, bleaching, and sheet formation, factors like mechanical agitation, chemical reactions, and temperature changes generate large amounts of foam. These seemingly harmless bubbles actually pose significant risks: they reduce pumping efficiency, affect pulp uniformity, cause sheet defects, and can even halt production.
Modern papermaking defoamers fall into three main categories: mineral oil-based, silicone-based, and polyether-based. Mineral oil defoamers are inexpensive but poorly suited to high-alkalinity environments; silicone defoamers work quickly but may affect sizing if overused; polyether defoamers excel in high-temperature resistance, making them ideal for thermomechanical pulp systems. Comparative tests at a Finnish paper company showed that for their CTMP system, composite silicone defoamers offered the best cost-performance ratio, requiring only one-third the amount of traditional mineral oil defoamers while improving defoaming efficiency by 50%.
The timing and method of defoamer addition are also crucial. In continuous pulping systems, multiple-point micro-dosing is more cost-effective than single-point bulk addition. A large paper mill in Jiangsu Province found that increasing defoamer addition points from three to five reduced total usage by 20% while achieving better defoaming results, saving over 800,000 yuan annually.
A more cutting-edge development is the research into "smart" defoamers. These products automatically adjust the release rate of active ingredients based on foam levels, achieving "on-demand defoaming." A German chemical company introduced a pH-responsive defoamer that remains stable under alkaline conditions and releases active substances only when encountering acidic foam environments, significantly extending its effective duration.
When silicone oil and defoamers work together, they often produce pleasantly surprising synergistic effects. In coated paper production, silicone oil improves coating fluidity while defoamers ensure the coating remains bubble-free, with the combination increasing coating uniformity by over 25%. A specialty paper company in Zhejiang resolved the long-standing "fish eye" problem in high-gloss art paper by optimizing the ratio of silicone oil to defoamer, increasing product yield from 85% to 98%.
This synergy is particularly evident in recycled paper pulping. Adhesives, inks, and other impurities in waste paper tend to produce stubborn foam that conventional defoamers struggle to handle. In such cases, using composite defoamers containing silicone oil not only breaks foam quickly but also forms a protective film on fiber surfaces, reducing subsequent foam generation. Operational data from a Swedish eco-friendly paper mill showed that this composite approach reduced defoamer usage in deinked pulp by 35% while increasing pulp yield by 2 percentage points.
It's worth noting that the precise use of silicone oil and defoamers is an art. Excessive silicone oil may hinder sizing, while overuse of defoamers can disrupt wet-end chemical balance. Thus, modern paper mills increasingly rely on advanced online monitoring systems and automated dosing devices. An intelligent dosing system introduced at a paper production base in Shandong Province adjusts silicone oil and defoamer additions in real time based on parameters like pulp flow, pH, and temperature, achieving dosing accuracy within ±2%.
As environmental regulations grow stricter, papermaking silicone oils and defoamers are undergoing a green revolution. Traditional APEO (alkylphenol ethoxylate)-containing defoamers are gradually being replaced by bio-based alternatives. A Brazilian biochemical company developed a natural ester-based defoamer extracted from sugarcane bagasse that is fully biodegradable and performs excellently in high-temperature, high-alkalinity environments, now successfully used in several large pulp mills.
The greening of silicone oil is equally remarkable. New modified silicone oils, incorporating hydrophilic groups like epoxy and polyether, have significantly improved biodegradability. EU-approved food-grade silicone oils are now widely used in napkins, food packaging, and other applications. More cutting-edge water-based silicone oil technology eliminates organic solvents entirely, achieving zero VOC emissions and representing the future of development.
Breakthroughs have also been made in recycling. Finnish scientists developed a technique to recover silicone oil from white water using special magnetic nanoparticles, achieving recovery rates over 70%. If widely adopted, this technology could reduce global silicone oil emissions by thousands of tons annually.
Looking ahead, with the integration of nanotechnology and biotechnology, papermaking silicone oils and defoamers will become more efficient, precise, and eco-friendly. Perhaps soon, we'll see self-regenerating "living defoamers" or "smart silicone oils" with sensing capabilities. These innovations will continue to drive the paper industry toward higher quality, lower energy consumption, and zero emissions.
In this digital age, paper remains irreplaceable. As "unsung heroes" of the papermaking process, silicone oil and defoamers continue to write new chapters in the story of human civilization's medium in their unique way. Every smooth page turn and every perfectly performing packaging sheet embodies the brilliance of these special chemicals.
