Sealant is a special material that serves many important purposes. It is made of polymer compounds with bonding and sealing properties and is mainly used for sealing waterproofing, vibration damping, etc. It is widely used in various fields.
Compared with other adhesives, silicones are compounds composed of elements such as carbon, hydrogen, oxygen, and silicon, which contain Si-C bonds and have at least one organic group directly attached to the silicon atom. These compounds are widely used in many industries due to their excellent physicochemical properties, and are also suitable for use in silicone sealants, so what can be called silicone sealant?
Silicone sealant is a high-performance, specialized sealing material in silicone adhesives, due to its unique chemical composition and performance, silicone sealant has a wide range of applications in many fields that use Polydimethylsiloxane as the main raw material, supplemented by crosslinking agents, fillers, plasticizers, coupling agents, and catalysts in a vacuum state mixed into a paste, at room temperature by reacting with water in the air, curing to form an elastic silicone colloid.
Here's some information about it:
- How to classify silicone sealant?
- What are the advantages of silicone sealants?
- What are the features of silicone sealant?
- What are the applications of silicone sealants?
- What are the problems of silicone sealant?
- How to make silicone sealant performance better?
1. How to classify silicone sealant?
Silicone adhesive sealant, also known as room temperature vulcanization silicone rubber sealant ( RTV ), is a silicone adhesive that can be hardened under the greenhouse. In an open environment, a cross-linking reaction takes place in the presence of water to form a rubber elastomer. According to the type of small molecules released, silicone sealant is categorized into de-alcoholized, de-acetone, de-acidified, and de-ketone.
XJY-8207S/M Hydrogen MQ Resin can be used as a tackifier for silicone sealant.
1.1 Deacidification
Characteristics:
- Competitive pricing compared to organic products
- Fast curing
- Catalyst-free version available
- Long shelf life
- Good transparency and clarity
- Bonding durability
1.2 Dealcoholation
Characteristics:
- Neutral curing
- Strong adhesion
- Economical
- Low VOC content, low odor, environmentally friendly
1.3 Deoximation
Characteristics:
- Fast curing
- Low catalyst option available
2. What are the advantages of silicone sealants?
Compared with other organic products (such as Polyurethane), silicone sealants have these features:
(1) Silicone sealant typically provides three times the durable protection of organics in the same application, thus avoiding premature failure and costly repairs.
(2) Organics are easily reversible-organic polyurethanes that lose their curing properties and revert to a substance as soft as chewing gum.
(3) The difference between silicone sealants and organic products is the difference between long-term value and premature failure, and silicone sealants win.
(4) Silicone sealant has a long life cycle, providing outstanding value to adapt to a variety of climatic applications and performance, and can combat ultraviolet light, ozone, rain, snow, and extreme temperatures more durable than organic products for long-lasting flexibility and adhesion.
3. What are the features of silicone sealant?
(1) Stability
If the completion of the correct curing, most silicone sealant products can be used in the temperature range of - 56 to 177 ° C (intermittent value of 204 ° C), there are some products with higher thermal stability, that can be used at a temperature of not less than 260 ° C (intermittent value of 315 ° C).
(2) Weather resistance
Silicone sealant is highly resistant to ultraviolet rays, i.e. radiation and weathering, preventing hardening, cracking, crushing, drying, and brittleness.
(3) Chemical Stability
Even after long-term exposure to a wide range of chemicals and atmospheric pollutants, silicone sealants do not degrade easily.
(4) Adhesive strength
Silicone sealants have excellent adhesion to a wide range of industrial materials, including glass, ceramics wood, painted surfaces, and many metals and plastics.
(5) Electrical properties
Designed with a wide variety of applications in mind, silicone sealants can be used in a variety of electrical and electronic applications, including devices that thermally cycle over a wide range of temperatures.
(6) Low flammability
In case of fire, silicone adhesives/sealants are not easily combustible. Many products meet UL flammability standards.
4. What are the applications of silicone sealants?
(1) All kinds of curtain wall weather sealing, especially recommended for glass curtain walls, aluminum composite panel curtain wall, stone dry hanging weather sealing;
(2) Metal, glass, aluminum, ceramic tiles, plexiglass, coated glass between the joints sealing, more used in home furnishing.
(3) Concrete, cement, rock, marble, steel, wood, anodized aluminum, and painted aluminum surface joint sealing.
5. What are the problems with silicone sealant?
The following Deketoxime type products as an example.
5.1 How do silicone adhesive sealants achieve curing performance?
One-component condensation curing silicone rubber products are cured using moisture in the air. Curing from the surface to the inside, usually at 25 ℃ and 50% RH conditions, one-component adhesive sealant 24h can be cured 3mm; it usually takes several days to form dry bonding surfaces and reach the inherent physical properties.
5.2 What are the differences in silicone sealants' surface drying time between winter and summer?
One-component condensation curing silicone rubber products table drying and curing speed and environmental temperature have a great relationship, winter humidity, low temperature, glue table drying, curing speed is slow, summer humidity, high temperature, glue table drying, clean surfaces curing fast.
5.3 How is silicone adhesive sealant temperature resistance?
General silicone temperature ranges from -40 ℃ to 20O0C, the long-term use of temperature does not exceed 150 ℃, special high-temperature adhesive red silicone temperature ranges from -40C to 250 ℃, long-term use of temperature does not exceed 180 ℃. Temperature resistance and whether the colloid is fully cured has a great correlation, not fully cured when heating will produce bubbles, cracking, smoking, and other undesirable phenomena.
5.4 Why is white silicone adhesive sealant easy to yellow?
Deketone-type silicone contains ketoxime crosslinking agent, amino silane tackifiers, and catalysts, in long-term ultraviolet irradiation or a high-temperature environment, due to the oxidation of the amino group or some chemical reactions of the catalyst, it may cause surface yellowing. To improve the yellowing phenomenon, special formulations are needed, such as solar silicone, which has good anti-yellowing properties. Dehydrated silicone in the case of not fully cured, not involved in the reaction of the titanate catalyst because of its own yellow color, in the heat conditions will be displayed so that the colloid yellowing.
5.5 Why does silicone sealant have viscosity difference between between winter and summer?
The viscosity of the glue will change with the temperature, high-temperature viscosity is reduced in summer, and winter is just the opposite, but it will be within the qualified range.
5.6 Why does produce "air dew" phenomenon in the closed system?
Deketoxime silicone sealant can be used in closed systems, such as lamps, headlights, and other industries, sometimes in the glass on the inner surface of a phenomenon similar to "air dew", which makes the transparency of the glass greatly reduced, affecting the glass transmittance and aesthetics. This is due to the closed system of sizing, de-aliphatic silicone curing the release of butanone oxime can not be discharged into the atmosphere in a timely manner and gathered attached to the surface of the glass caused by; the use of de-alcoholized silica gel can be more easily avoided this kind of aerosol phenomenon, because of its curing release of the products of the alcohols, at room temperature for the gas, will not be gathered adhering to the surface of the glass.
5.7 How to improve the silicone sealant's curing speed?
Greater than 6mm curing thickness, it is recommended to use 2 times the application of silicone sealant; improving the temperature and humidity can accelerate the curing speed of the product, but the temperature should not be more than 50 ℃, increase the effect of humidity is better than raising the temperature!
5.8 How to remove silicone sealant?
Before the curing of silicone, you can use a putty knife to scrape off the uncured paste to clean surfaces, and then use petroleum ether to clean the residue. After the silicone curing: First, you can use a knife or razor to mechanically scrape off as much silicone as possible, and then use a solvent to remove all kinds of oil residue or silicone, soak the silicone in such solvents overnight to let it dissolve before cleaning. After these steps, the product can be tack-free again.
6. How to make silicone sealant performance better?
Silicone sealant (silicone adhesives) is widely used for multi purpose in daily life, including the automotive electronics industry (including automotive accessories, lamps, lathe sealing, etc.), household appliances (such as refrigerators, kettles, induction cookers, microwave ovens, ovens, electric irons, etc. need to use silicone bonding sealant), lamps, tube, engineering machinery, control module bezel sealing and waterproofing, circuit board components are fixed, fixed wires and industrial setting. How to improve the competitiveness of your products?
XJY Silicones is one of the leading silicone MQ resin and VMQ silicone manufacturers in China, with more than 30 years of R&D and manufacturing experience in the silicone industry as well as more than 15 related patents and technical support. Our silicone raw products can meet the needs of silicone sealants and support the provision of diversified customized solutions.
