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Silicone Resins: Heat resistant coatings
Fig 01: Heat resistant coatings used in infrastructure (the metallic paint)
Heat resistant coatings are used frequently in industrial coating applications that can protect the substrate at high temperatures (more than 180 °C). As a result, these are the primary choice of coatings to protect ovens, kettles, pipelines, exhausts, heat exchangers, chimneys, auto engines and stoves.
Silicone Resin
Standard heat-resistant paint formulations can tolerate heat only up to 150-200 °C and frequently use a variety of organic resins as binders, including epoxy, polyester, alkyd and acrylic. Such paint formulations must include silicone resins as an essential ingredient in order to boost their capability for heat resistance.
Silicone resins have numerous important feature besides heat resistance, such as great weather ability, superior dielectric and water repellency capabilities. This improves durability and the reliability of the coatings.
Silicone resin reaction process: The polycondensation type reaction.
Silicone resins can be produced by hydrolyzing mixtures of chlorosilanes or alkoxy silanes to form highly reactive silanol groups:
Reactive silanol initially condense to form oligomer siloxane structures:
Further condensation occurs to form three-dimensional siloxane lattices. Driving the condensation by applying heat and catalysts increases the molecular weight and improves physical properties.
The most significant monomer in silicone resin technology by volume is methyl-trichlorosilane. Silicone resins are often produced by combining multiple raw materials to incorporate multiple functional groups. Methyl silicone resins (R=methyl) have a high degree of hardness and cure quickly, but also exhibit brittleness, poor pigmentability, and poor compatibility with organic resins.The phenyl silicone (R=phenyl) based resins have great thermal stability, good pigmentability, and increased compatibility with organic resins, but it also produces products that are much more cross-linked and have lower thermoplasticity than those having methyl groups. A majority of silicone resins are of a mixed methyl phenyl type. The performance of the product can be determined by the methyl to phenyl molar ratio.
Types of silicone resins:
Methyl silicone resin:
A type of silicone resin having a completely methyl-based organic substituent group that produces hard films with high moisture resistance, dielectric characteristics, water repellency, dirt repellancy, UV resistance and releasing qualities. Coating made of this alone can resist temparatures of 400 C.
Methyl/Phenyl silicone resin:
The organic substituent group in these resins, which consists of methyl and phenyl groups, gives them great heat resistance, mechanical strength, water/UV resistant, and gloss. Heat resist up-to 650 °C
Organic resin modified silicone resin:
The silanol functionality can be reacted with hydroxyl groups on organic resins (e.g., polyesters, epoxy, alkyds, etc.) to form silicone-organic hybrid resins with performance improvements proportionate to the level of siloxane modification. They form a coating with the advantages of organic resins (such as mechanical properties, curing profile, economy and adhesion)
While silicone resins can enhance the paint’s thermal, chemical, and UV radiation resistance, a combination of silicone and organic binders will also improve several performance characteristics and physical features like making air dry acrylics, higher corrosion resistant epoxies and tougher alkyds.
Thermal properties of silicone resin:
The thermal behaviour of the silicone resin was analysed by thermo gravimetric analysis at a heating rate of 10°C/min from room temperature to 800°C under an air. In the examples below,
- Sample A : 100% Methyl silicone resin compound.
- Sample B : 50% Methyl 50% phenyl silicone resin compound.
- Sample C : High MW 25% Methyl 75% phenyl silicone resin in solvent.
Thermal degradation behaviour of all samples in air were summarized in Table 1.
Table 01: Thermal degradation data by TGA analysis.
T10% represented the temperature at which the mass loss was 10 wt% of the system. Tmax represented the temperature of the maximum mass loss rate of the system.
The Td (temperature degradation) increased as the silicone resin’s phenyl content increased due to the silicone resin’s rising molecular weight. This could have prevented the -Si-O and -Si-Me groups from breaking down.
The temperatures of the maximum degradation rate (MRD) of silicone resin containing phenyl (Sample B & C) were lower than those of the silicone resin without phenyl (Sample A). This indicated that the thermal decomposition rate of the silicone resin slowed down with the addition of the content of the phenyl group moiety.
Silicone resin : Binders for heat resistant paint
For many years coatings based on methyl/phenyl silicone resins have proven to be one of the most effective and reliable products within the high heat and protective coatings segments. Fillers inorganic characters along with the methyl/phenyl modification provide outstanding long term thermal stability, attractive corrosion protection, weather resistance and good mechanical properties. In general, silicone resins for high heat applications can be categorized into two sub-groups: i) Heat curing and ii) Air curing systems.
Metal alkoxide catalysts were utilized in the moisture-curable air cure system to induce crosslinking. The silicone resin’s hydroxyl groups and moisture in the environment can react with the catalyst to crosslink the polymer.
The methyl silicone resin has a tremendous potential for heat resistance up to 400 °C, however methyl phenyl silicone resin performs better at higher temperatures up to 650 °C. Based on the formulas, modified polyester silicone resin and epoxy silicone resin can withstand heat up to 350-550 °C.
Summarized data of silver heat resistant paint having silicone resin used as binders.
Table 02: silver heat resistant paint test data
Fig: 02 Sample A – Methyl silicone resin metallic paint formulation – quenching at 450°C pass other 500°C and 600°C failed
Fig 03 Sample B – Methyl phenyl silicone resin metallic paint formulation– quenching at 450°C/500°C/600°C pass
Fig 04 Sample C – High phenyl silicone resin metallic paint formulation – quenching at 450°C /500°C /600°C pass
In conclusion, the TGA and metallic paint testing results demonstrated that changing the methyl and phenyl ratio of silicone resin improves the thermal stability. The UV resistance and corrosion resistance are extremely good of heat resistant coating. The silicone resin’s outstanding durability and substrate adhesion are demonstrated by the adhesion test that done after the quenching test. These resins are excellent for many various types of protective coatings.
—- Elkay Chemicals Pvt. Ltd. India.
This blog is the copyright of Elkay Chemicals Private Limited. All content, including text and images, is owned by Elkay Chemicals Pvt. Ltd. and may not be reproduced or distributed without the express written permission of Elkay Chemicals Pvt. Ltd.
Silicone-Based Hair Serum
Silicone-Based Hair Serum
Unlocking the Secrets to Silky, Shiny Hair
Silicones is an essential part of the haircare regime:
Silicone is a versatile ingredient that has gained popularity in the world of cosmetics. It is widely used in various skincare, haircare, and makeup products due to its unique properties. This broad variety of compounds confers qualities including good spreading, film formation, wash-off resistance, skin feel, volatility, and permeability, which have an impact on the performance of practically every type of cosmetic product.
When it comes to hair care, we’re always on the lookout for products that can transform our tresses and give us that enviable, salon-worthy look. One such product that has gained popularity in recent years is silicone-based hair serum. This versatile hair care product has become a staple for many, thanks to its ability to deliver smooth, shiny, and frizz-free locks. In this blog, we will dive into the world of silicone-based hair serums, exploring what they are, how they work, and the benefits they offer.
Silicones in hair serums:
These serums are typically formulated with silicone derivatives, such as dimethicone or cyclomethicone, which are lightweight, clear, and non-greasy substances. Dimethicone is coated on individual hair and prevents the clumping of hairs. Silicone itself is a synthetic compound that forms a protective coating over the hair shaft, helping to seal in moisture and protect against external damage. This unique property makes silicone an excellent ingredient for hair serums, as it provides a multitude of benefits.
Making your hair look healthier:
One of the primary advantages of silicone-based hair serums is their ability to create a smooth, sleek appearance by coating the hair strands. This coating helps to reduce friction and prevent tangling and breakage, making it easier to comb or brush through the hair. Moreover, the silicone coating fills in any gaps in the hair cuticle, resulting in a more uniform surface and enhanced light reflection, which leads to a lustrous, shiny finish. This silicone coating is easily removed by shampoo wash. We have analyzed the scanning electron microscopy (SEM) of control hair and silicone hair serum-coated hair, denoted in Fig. 1.
Frizz control is another area where silicone-based hair serums excel. The silicone coating helps to seal the hair shaft, preventing moisture from entering or leaving the hair. This not only reduces frizz but also provides a protective barrier against humidity, which is often the main culprit behind frizzy hair. By taming frizz and flyaways, silicone-based serums can help achieve a polished, sleek hairstyle that lasts throughout the day. In addition to their smoothing and frizz-controlling properties, silicone-based hair serums can also offer heat protection. These serums create a barrier between the hair and heat-styling tools like straighteners or curling irons, reducing the damage caused by high temperatures. This is especially beneficial for those who frequently use heat styling tools, as the silicone coating helps to minimize moisture loss and protect the hair from becoming brittle and prone to breakage.
Finding the right balance:
While silicones provide numerous benefits, using too much product or applying it to the scalp can lead to a heavy, greasy feeling. It’s best to start with a small amount and distribute it evenly through the mid-lengths and ends of the hair, where it is most needed. Additionally, regular shampooing is necessary to prevent product buildup and ensure that the hair remains clean and healthy.
While silicone-based hair serums offer many advantages, it’s important to note that they are not a cure-all for all hair concerns. If you have specific hair issues like extreme damage or scalp conditions, it’s advisable to consult with a professional hairstylist or trichologist who can provide tailored advice and recommend appropriate treatments.
In conclusion, silicone-based hair serums have become a go-to product for achieving silky, shiny hair. Their ability to smooth, control frizz, and provide heat protection makes them a valuable addition to any hair care routine. By understanding how these serums work and using them appropriately, you can unlock the secrets to beautiful, healthy-looking locks. So why not give silicone-based hair serums a try and experience the transformative power they can have on your hair?
—- Elkay Chemicals Pvt. Ltd. India.
This blog is the copyright of Elkay Chemicals Private Limited. All content, including text and images, is owned by Elkay Chemicals Pvt. Ltd. and may not be reproduced or distributed without the express written permission of Elkay Chemicals Pvt. Ltd.
Silicone chemicals in cosmetics applications and their implications to the environment, health and sustainability
Abstract
Silicone chemicals exhibit unique surface as well as bulk properties that make them highly desirable for cosmetic applications. These include chemical inertness, biocompatibility, lubricity, comfort feel, slippery feel, compatibility with various formulations, hydrophobicity, hydrophilicity, broad synthetic molecular design options, and unique ability to combine several properties into one single molecule. These properties are possible due to unique molecular characteristics such as low surface energy, flexible bonds, high bond energy; high thermally stability. In recent times, these characteristics are becoming more relevant when viewed from the standpoint of environmental compatibility and overall sustainability.
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REDEFINING OPPORTUNITY FOR THE SILICONE INDUSTRY – COVID 19
Global trends in the silicone industry by Dr. Ravi Kulkarni (Managing Director, Elkay Chemicals)
Silicone industry was born towards the end of WW II as a material used to create high performance grease for lubricating crucial military hardware. Since then, the industry has expanded multifold into both common and high-end performance applications. These were to be the first commonly available non-carbon polymers and had several unique attributes as a material. Over 7000 products have evolved since then as high performance additives in diversified industry segments such as textile finishing agents, petroleum refinery additives, agricultural adjuvants, construction chemicals and sealants, paints and coatings, rubbers, plastic and rubber release agents, medicament, pharmaceutical intermediates, personal care hair and skin case additives, high performance foam stabilizers and destabilizers.
Click on link to read more ……… Redefining opportunity for the silicone industry-COVID 19
Reference : Article published in Chemical today magazine – June 2020.
Silicone in Cosmetics
Vinay Kumar Singh
Chief Research Officer,
Paramount Cosmetics India,
Bangalore, Karnataka
vinay@parammount.com
Silicones used in personal care applications are of diversified types, including cyclic, linear,or organo-functional polydimethylsiloxanes (PDMS), as well as silicone elastomer
dispersions and resins. This wide range of molecules provides benefits that impact the
performance of almost every type of beauty product, conferring attributes such as good
spreading, film forming, wash-off resistance, skin feel, volatility and permeability.
I as a Chemist have been benefitted by use of Silicones many a times. In fact it has helped me formulate products that were really a challenge. No doubt, I advocate that Silicone Chemistry is future of Cosmetics.
Now as there have been few concerns particularly environmental, we; Chemists have to find solution to it to use Silicone without any fear or risk.
First introduced to beauty products in the 1950s, silicones are derived from a natural product called silica (basic sand), but undergo extensive chemical processing before being added to our beauty products.
The term silicone represents a large family of polymers that range from low viscosity fluids, to viscous gums, to cross-linked elastomers and hard resins. Their unique chemical and physical properties have made silicones important ingredients. It is best known for their aesthetic properties, these versatile materials improve the performance of many cosmetics, sunscreens and skin treatment products. They help deliver pigments and other particles to the skin, enhance protection by sunscreens and improve the stability of antiaging ingredients.
The first applications involved basic silicone fluids (INCI: Dimethicone). These linear polymers are liquid over a wide range of molecular weights. Dimethicones remain important for their emollient properties and their ability to improve the skin feel of many types of skin care formulations. In the late 1970s, another important class of silicones was introduced to the industry. Cyclomethicones are volatile, low-viscosity silicone fluids that act as cosmetic solvents. They are particularly suited for use with other silicones and as delivery vehicles for a variety of active ingredients.
Starting in the 1980s, the increasing popularity of silicones in skin care applications prompted silicone manufacturers to develop a variety of new materials, which led to even broader use. Many of the new silicones were derivatives of dimethicones, where specific functional groups were added to the backbone of the silicone polymer. For example, grafting hydrophilic polyethylene oxide chains to the dimethicone backbone produces non-ionic silicone surfactants that are useful as emulsifiers, foam stabilizers and wetting agents. Another family of silicones was created by introducing phenyl groups onto the silicone backbone to produce fluids with a higher refractive index and increased compatibility with cosmetic waxes. These phenyl silicones are useful for color cosmetics such as lipsticks, where the goal is to produce a high gloss coating on the lips.
One of the newest and most rapidly growing classes of silicones used in skin care applications is silicone elastomers, which are made by cross-linking dimethicone polymers to produce elastomeric solids that have properties quite different from dimethicone fluids. As the degree of cross-linking increases, the silicone network becomes more rigid. Although they are produced by a different process, silicone resins can be thought of as representing the most extreme examples of cross-linked silicone polymers. Silicone resins have a tight, three-dimensional structure that results in rigid materials that can form hard, durable films.
There are numerous forms of silicones used in cosmetic products, particularly leave-on skincare products and all manner of hair-care products.
Silicones go by different names and are modified into numerous different formulas in order to perform the specific role expected of them like waterproofing, retaining moisture, adhering colour pigments, protecting our hair and imparting smoothness, and making the application of skincare products feel silky i.e. no tugging on the skin as it is spread on, and no oily, sticky feeling. They give our deodorants that velvety feel, allowing them to dry quickly, and they keep water-resistant sunscreens on our skin, even when we sweat or get wet.
In any product, all ingredients must be suspended in some base formula; some of the ingredients remain on the surface, some are absorbed. The intent is for the “actives” to get through. Moreover, the molecular structure of commonly used silicones makes it impossible for them to suffocate skin (not to mention skin doesn’t breathe). The unique molecular structure of silicones (large molecules with wide spaces between each molecule) allows them to form a permeable barrier and also explains why silicones rarely feel heavy or occlusive, although they offer protection against moisture loss. Interestingly, silicone has been shown to be helpful for offsetting dryness and flaking from common anti-acne active ingredients such as benzoyl peroxide and topical antibiotics. Also, silicones are sometimes used as fillers to improve the appearance of acne scars, which certainly wouldn’t be the case if silicone were a pore-clogging ingredient. Perhaps the most telling reason why silicones do not clog pores and cause acne (or blackheads) is because, from a chemistry standpoint, most silicones are volatile. That means their initially viscous (thick) texture evaporates quickly and does not penetrate the pore lining where acne is formed. Instead, they help ensure the even application of other ingredients and leave behind a silky, almost imperceptible feel that noticeably enhances skin’s texture and appearance; without irritation.
When it comes to our hair, silicones are conditioning workhorses. They are in most of shampoos, conditioners and treatments, and many styling products; the most common are dimethicone and cyclomethicone. They can repair signs of damage, fill in cracks and crevices in hair’s surfaces, return water resistance to damaged areas and prevent new damage from occurring.
Silicones have revolutionized the application and longevity of most makeup products, including foundation, eyeshadows, blushes, and liquid and pencil eyeliners.
Silicones are critical in many foundation formulations to give them more ‘spreadability’ and a luxurious, comfortable feel on skin. Silicones in liquid foundation help keep it flexible on the face and maintain a fresh, dewy look. Without their benefits, you could be left with dry powder on your face, which would be more likely to move into wrinkles or laugh lines.
Silicones are used to increase water resistance in a formula. This is particularly useful for sun-protection products, foundations and powders, especially those that make the claim of being water-resistant and waterproof. We also use them to resist transfer onto clothing.
Today’s “state of the art” liquid foundations often are formulated as w/o emulsions. Unlike conventional emulsions where the oily (water-insoluble) ingredients are dispersed as droplets in water, w/o emulsions are droplets of water dispersed in the other ingredients (e.g., oils or silicones). For a foundation that incorporates silicones with hydrophobic pigments, w/s emulsions are ideal vehicles. Such formulations have pleasant aesthetics, excellent spreading characteristics and optimize the film-forming properties of silicone resins.To prepare stable w/s emulsions, special polymeric silicone emulsifiers are required. These emulsifiers are made by grafting hydrophilic groups such as polyethers onto a dimethicone backbone. Common examples are PEG/PPG-18/18 dimethicone, bis-PEG/PPG-14/14 dimethicone and cetyl PEG/PPG-10/1 dimethicone. Silicone emulsifiers are typically liquid at RT and do not require waxes for emulsion stabilization, which creates a heavier feel. Formulators can explore new possibilities with silicone emulsifiers to respond to ongoing consumer demands for next-generation products with innovative textures, feel and improved performance.
Even the lips are not immune to silicone’s charms. It makes Lipstick last for hours. Another important property of silicones is their ability to act as a carrier for colour pigments. ‘If you want a high-performance, long-lasting lipstick, you need silicones.
Silicone resins such as trimethylsiloxysilicate and polymethylsilsesquioxane are film-formers that improve adhesion of pigments to the skin and transfer resistance. These resins are soluble in cyclomethicone and many other silicone fluids so they are easy to incorporate into cosmetic products. They can also be used in lipsticks to provide long-lasting color with greatly reduced transfer properties. In lip products, a high gloss film as well as attractive color is desirable. Phenyl silicones such as phenyl trimethicone are popular in this application. In addition to imparting gloss, phenyl silicones are more soluble in cosmetic waxes used in lipstick, a property that reduces the problem of syneresis, or bleeding of oil from the lipstick.
Silicone in hiding wrinkles: A better approach to concealing wrinkles is to apply materials with optical properties that allow them to reflect and scatter light in such a way as to reduce the visibility of wrinkles and other skin imperfections. This phenomenon is often referred to as the “soft focus” effect because it is similar to what happens when skin is photographed with a camera that is out of focus; skin features such as wrinkles are “blurred” by the effect of the treatment. Silicone fluids offer the same benefits for delivering soft focus particles to the skin. The refractive index of the silicone can be adjusted by choosing a dimethicone fluid or a phenyl silicone that has a higher refractive index. Spherical silicone elastomer and silicone resin particles are gaining in popularity for face care products. These are useful for soft focus applications because they have a different refractive index than organic cosmetic oils. Light scattering typically increases when the oils and the particles in the film have different refractive indexes. Apart from their aesthetic and optical properties, silicone elastomer particles offer the added benefit of absorbing sebum.
Skin Aging prevention: Many anti-aging skincare products use silicone elastomers. These are our friend when it comes to hiding the telltale signs of aging. They impart a soft, bouncy feel to the skin. They also optically help blur fine lines and wrinkles, so they have really advanced the anti-aging category.
Many skin care products make claims for the prevention of skin aging by protecting the skin against the damaging effects of pollution, cigarette smoke, free radicals and other environmental insults. These claims have some scientific basis, but by far the most important factor in skin aging is exposure to the ultraviolet radiation in sunlight. Countless studies have shown that ultraviolet radiation causes cumulative skin damage that leads to loss of elasticity, uneven pigmentation and other signs of aged skin. The most effective prevention is regular use of sunscreen, which protects the skin against exposure to ultraviolet radiation.
Silicone fluids are widely used in sunscreen formulations because of their ability to reduce the oily and sticky skin feel associated with high levels of organic sunscreen oils. Silicone fluids with phenyl groups have better solubility in sunscreen oils and this can increase the effectiveness of the sunscreen, presumably by producing a more uniform film on the skin. Silicone waxes in which long-chain alkyl groups have been grafted onto the silicone backbone have been shown to increase the protective effect of sunscreens. These silicone waxes are solids that affect the rheology of the formulation; they increase the viscosity of the sunscreen film on the skin so that it has a greater tendency to stay in place.
A number of different polymers are used to increase the water resistance of sunscreen formulations. Many are acrylate polymers and silicone manufacturers have produced hybrid silicone-acrylate copolymers that offer the benefits of both. Other silicone film-formers such as silicone resins have been shown to increase the water resistance of sunscreens.
Cyclomethicone is a popular carrier fluid for inorganic sunscreen dispersions, particularly when the sunscreen particles have a surface treatment to make them more hydrophobic. Silicone additives such as polyether-modified dimethicones are included to prevent re-agglomeration.
This Article is written by Mr. Vinay Kumar Singh, Chief Research Officer, Paramount Cosmetics India.