What Are the Unbeatable Advantages of Silicone Emulsion in Industrial Applications?

The Importance of Silicone Emulsions in Metal Casting and Rubber Vulcanization

Silicone emulsion remains thermally protective and maintains its integrity even in extreme manufacturing conditions. In metal casting, silicone emulsions form protective layers on mold surfaces that withstand temperatures between 700 and 1600 degrees Celsius. The emulsions even mitigate thermal shock. In rubber vulcanization, silicone's low surface tension silicone evenly covers curing molds, so rubber stays flexible after exceeding 200 degrees Celsius. Silicone does not degrade, nor do other materials. Silicone's thermal stability can be attributed to its unique siloxane backbone of silicon-oxygen. The bond energy required to break these siloxane bonds is 452 kilojoules per mole, which is 1.5 times the required energy to break carbon-carbon bonds in the majority of organic polymers. This makes silicone emulsions ideal over competitors in high temperature applications.

Why siloxane backbones outperform organic polymers under heat

Siloxane backbones are heat-resistant due to three factors.

1. Bond Strength - Si-O bonds are stronger than C-C bonds. Si-O bonds are measured at about 452 kJ/mol while C-C bonds are about 347 kJ/mol.

2. Methyl Group Resistance - Methyl Group layers are protective to siloxanes because siloxane covered methyl groups oxidize at 250°C, while other oxidizing compounds do not provide this protective layer.

3. Chain Mobility - Si-O-Si linkages provide flexibility to the bonds, preventing embrittlement, which allows the siloxane to survive many cycles of heating and cooling.

Siloxane networks do not undergo structural degradation until 300°C, while organic polymers undergo chain scission and structural degradation at about 150°C. Silicone treated components show 80% less deformation (when measured using the ASTM E2550 parameters) after 500 hours at 280°C. This level of performance supports siloxane based components to be used without reservation in high continuous heat applications such as glass making and sealing of turbines.

Enhanced Water Repellency and Hydrophobicity in Control and Textiles

Real World Performance: Water Beading on Perlite Insulation and Breathable Cotton Canvas

Silicone emulsions offer strong and permanent water resistance across many substrates. The Industrial Perlite Insulation water penetration case shows that instead of getting trapped in a wet environment, moisture beads and rolls away, helping to preserve the insulation's effectiveness. In textile applications, silicone emulsion treated cotton canvas is able to remain breathable and water resistant at pressures above 500 Pascals. This is critical in allowing and preventing liquid water ingress and outflux, which is the primary reason for its use in military jackets and outdoor apparel. In at least two different field studies conducted by textile manufacturers, the water-repellent treatment was found to retain at least 95% of its water-repellent properties after an estimate of fifty washes. This means functionality is maintained without compromising comfort and the ability to breath in all weather conditions.

Surface science: methyl-terminated PDMS films lowering surface energy below 25 mN/m

The methyl groups that are part of the polydimethylsiloxane (PDMS) chains are responsible for the hydrophobic characteristics of PDMS. These Chainlike molecules reduce surface energy below 25 mN/m, which leads to water contact angles exceeding 110 degrees, beneficial for water to roll of the surface. What is also positive is that the emulsion spreads out to form really thin, even layers. There is also a reduction of the tiny molecular attractions (van der Waals) that exist between the liquid and solid surfaces, which is a good explanation for why surfaces remain clean for extended periods after treatment. PDMS was shown to adhere to multiple porous surfaces, including concrete, various fabrics, and insulation materials. This suggests that the water repelling effect is consistent regardless of the type of material, making the PDMS treatment adaptable to a variety of practical uses.

Excellent Lubricity & Low Friction Release in Molding & Engineering Applications

65% decrease in ejection force with silicone emulsions in thermoplastic injection molding

Silicones emulsions display excellent lubricating characteristics, which facilitate precision molding operations. Their PDMS structure generates low surface tensions in contrast to most petroleum-based release agents. Compared to conventional release agents, Silicones emulsions have been shown to reduce ejection force by approximately 65% when thermoplastic injection molding is employed. This translates to reduced distortion when parts are removed, more consistent dimensional accuracy, and less frequent cleaning and maintenance of molds. In addition, PDMS will be thermally stable and will form a protective layer that will remain intact when temps exceed 200 C, which is a problematic condition for most organic release agents which will either decompose or evaporate. In practice, molds are able to release parts without residue which is particularly advantageous for complex, deep, and highly detailed molds. This is also true for long production runs.

Formulation Flexibility: Why Silicone Emulsion Outperforms Neat Silicone Oils

The stable incorporation into waterborne systems, such as acrylic automotive clearcoats.

There is a balance between performance and processing requirements, and silicone emulsions find that balance due to how emulsions are stable in waterborne systems which means there is no separation, no clumping, no migration, and as a result nothing that would disrupt the system. Because of this silicone emulsions can be incorporated into acrylic clearcoats automotive manufacturers can use them without worrying about uneven films, dull areas and adhesion failures. Additionally, since no solvents or chemical additives are emulsified, manufacturers can realize a 30-50% reduction in VOC emissions compared to conventional solvent-based products. This kind of flexibility is not just limited to clearcoats, it is also being applied to industrial coatings, fabric treatments, construction sealants, etc. and maintaining the high standards of performance and quality associated.

Silicone emulsions and their siloxane backbones are more stable than traditional organic polymers which is extremely useful in application like metal casting and rubber vulcanization.

What role does silicone emulsion play in making textiles water resistant?
Silicone emulsion has hydrophobic properties because of its methyl groups bonded to the PDMS chains which causes silicone to make the surface energy drop below 25 mN/m. This means that the textiles treated with silicone emulsion can make textiles water resistant, while still being breathable and usable in all weather conditions.

Can silicone emulsion be used in thermoplastic injection molding?
Yes, silicone emulsion will decrease ejection force in thermoplastic injection molding and will help with the precision of the molded parts and decrease the amount of cleaning that needs to be done to the mold. The PDMS structure has low surface tension, and the structure will not break down even in high temperatures.

Why is silicone emulsion preferred to neat silicone oils?
Silicone emulsion integrates more easily and remaining stable within the waterborne system, which is helpful in cases like with the formulations of acrylic automotive clearcoats, where neat silicone oils would cause clumping or separation. Also, silicone emulsions are more environmentally friendly, with VOC emissions 30-50% lower than those of solvent based products.