Introduction to Hydroxy Silicone Oil
Release Time: 2022-11-29 10:54:15
Introduction to Hydroxy Silicone Oil
Hydroxyl Silicone Oil (Photo taken by Hubei Shengbangfan)
Cover Photo Cited from: https://pixabay.com/photos/analysis-biochemistry-biologist-2030265/
There are many different types of silicone oil in today’s organic silicon industry. The common ones are like dimethyl silicone oil, silicone rubber and etc. Today, we are going to introduce another type of common silicone oil which is hydroxy silicone oil.
Hydroxyl silicone oil is an oily silicone liquid of linear polydimethylsiloxane with hydroxyl end group. It has the characteristics of methyl silicone oil. Low viscosity hydroxyl silicone oil is an excellent good structure control agent in silicone rubber processing, which can replace diphenyl silyl glycol, simplify the process and improve the process performance. It is also used as a waterproof, soft and anti-sticking agent for fabrics, leather and paper. The molecular formular of hydroxyl silicone oil is (C2H6OSi)nC26H54O5Si2.
In hydroxyl silicone oil, the Si-O chemical key has high thermal stability; The Si-O-Si bond has a dipole induction effect on the hydrocarbon group connected to the Si atom, which can improve its stability. The structure of siloxane chain also endows silicone with low surface tension and weak intermolecular force, and hydroxyl silicone oil has good hydrophobicity due to its special structure. The intermolecular force of methyl is inversely proportional to the sixth power of the intermolecular distance. As the distance changes, the intermolecular force will be weakened. Therefore, the molecular force of dimethylsiloxane is much weaker than that of hydrocarbons, so its surface tension is smaller than that of hydrocarbons with similar molar mass. The low surface tension of polysiloxane makes hydroxyl silicone oil easy to spread on the interface.
High viscosity hydroxyl silicone oil is oligosiloxane which is polymerized by the ring. Hydroxyl silicone oil is reactive and can react with hydroxyl or alkoxy compounds under the catalysis of organic tin It has excellent electrical insulation and high and low temperature resistance, high flash point, low freezing point, and can be controlled between -50℃ and 25℃ and has a long-term use under these conditions. The hydroxyl silicone oil also has features like low viscosity temperature coefficient, high compressibility, low surface tension, good hydrophobicity and moisture proof property, chemical inertness and physiological inertness.
Hydroxyl silicone oil is generally used with curing agent to achieve cross-linking and curing. When it is used for anti-stick paper, it must also be fixed with coupling agent. Generally, the amount of curing agent accounts for 3~5% of the base adhesive, and the coupling agent accounts for 0.5~1% of the base adhesive. In most cases, the base adhesive is diluted 10 times with solvent first, then added with curing agent and coupling agent to stir evenly, and then coated on the surface of the base material, cured at room temperature or by heating. It takes more than 30 minutes at room temperature and 30 seconds for heating at 120℃~150℃. It is used for sealant and mold adhesive without solvent. Add curing agent and mix well (curing agent is different for single component and two-component). After defoaming, it can be cured for 30~120 minutes.
Applications of Hydroxy Silicone Oil
1. Used as leather finishing agent.
The film forming material used as leather finishing agent in the finishing layer has a great influence on the physical properties of the finished leather, especially the top coating gives the finished leather surface many high-quality characteristics like water resistance, solvent resistance, mechanical scratch resistance and other properties, which plays a decisive role in the appearance of the leather. It is due to the introduction of hydrophilic ionic groups in the molecular chain of polyurethane, the leather coated with has poor water resistance, which can be improved by adding hydroxyl silicone oil. Hydroxyl silicone oil is a kind of material with good hydrophobicity, air permeability and weather resistance. When it is used in the synthesis and modification of waterborne polyurethane, the leather after finishing will have better wet abrasion resistance and feel smoother and more comfortable.
2. Used as leather backing agent.
When finishing the back sealing of some leather, because the coating is not resistant to the immersion damage of the solvent in the shoemaking adhesive, the coating will peel off. Hydroxyl silicone oil can effectively solve the peeling phenomenon when finishing the back seal because of its good air permeability, weather resistance, corrosion resistance and non-toxic advantages.
3. Used as add-ons to textiles.
Textile auxiliaries can be used as fabric softener, lubricant, waterproof agent and finishing agent in textile and garment industry. In order to meet the high-end needs of textiles, chemical products are also constantly developing hydroxyl silicone oil that can be used in the same bath as various functional additives such as waterproof agent, flame retardant, antistatic agent and color fixative, and has a good feel. In addition, in order to improve the performance of the fabric, there are hydroxy silicone oil products that can be used in the same bath with dyeing, cotton silicone oil with a cool feeling, hydroxy silicone oil products that can improve the hand feel of the fabric, and hydroxy silicone oil type deepening agents that can give the fabric excellent darkening effect, good storage stability, do not affect the color fastness, and have a good hand feel. In addition to the functionalization of textiles as additives in textiles, hydroxyl silicone oil products will also be used in other fields of textiles, such as the coating of fabrics formed by the combination of organic silicon and polyurethane; Printing of fabrics formed by polymerization of organic silicon and acrylic acid; Organic silicon and organic fluorine are combined to form a waterproof coating on the fabric surface.
4. Used in coating industry.
The hydroxy silicone oil used in the coating industry can improve the production process of the coating, maintain the storage stability of the coating, improve its construction technology, improve product quality, and endow the coating with some special functions, such as leveling, scratch resistance, adhesion resistance, pigment dispersion, smoothness, special surface effect, wetting, hydrophobic, defoaming and foam inhibiting, etc. Now hydroxy silicone oil has become an indispensable component in coatings. Reasonable and correct selection of hydroxy silicone oil additives can effectively reduce costs and improve benefits. Different coating systems use different hydroxyl silicone oil additives, but each additive has multiple effects, and sometimes it can also be used in other systems.