RTV Silicone Rubber

The term RTV is means Room Temperature Vulcanising, All rubber that cures at room temperature is considered RTV.

RTV (room-temperature-vulcanizing) silicone rubber is a type of silicone rubber that cures at room temperature. RTV is available as a one-component (RTV-1) or two-component system (RTV-2).

RTV silicone rubber can be cured with a catalyst consisting of either platinum or a tin compound such as dibutyltin dilaurate. The most common RTV silicones use a tin catalyst together with moisture from the atmosphere to cure the rubber, these are and are known as Condensation Cure. There are RTV compounds that use platinum catalysts are known as Addition Cure and these cure without the need of moisture. The cure speed of Addition cure RTV’s can also be accelerated using elevated temperatures.

Advantage & Disadvantage 

1. Good characteristics of easy operation
2. Light viscosity and good flow-ability
3. Low shrinkage
4. Favorable tension
5. No deformation
6. Favorable hardness
7. High-temperature resistance, acid and alkali resistance, and ageing resistance

Disadvantages: One of the disadvantages of RTV silicone is that it can be more expensive and is prone to attracting dirt and residue. Because air moisture cures RTV, it needs to be applied to a surface rapidly, which can be difficult. The silicone is very thick and porous, so it needs to be degassed with a vacuum, so as to remove any air bubbles which could affect its application.

Applications

Room temperature vulcanized silicone rubber is one of the most commonly used silicone rubbers in industrial and personal applications. It is a multifunctional compound with multiple uses in various industries. Typical uses are as follows:

Silicone Mold

Due to its performance advantages and versatility, RTV silicone rubber is becoming the preferred choice of many silicone mold makers. It offers a number of benefits for the mold-making process, including excellent thermal resistance and long-lasting flexibility.

Sealants

In addition to mold-making, silicone is widely used in other fields such as bonding, sealing, potting, encapsulation, coating and casting. RTV silicone is easily bonded to common household materials, such as wood and ceramic tiles. A bead of natural cure silicone sealant is applied around the windows of your home to prevent water from entering the house from outside. It is suitable for bathroom sinks, showers and bathtubs, and toilets. In the kitchen, it is also used around sinks and faucets.

Types

RTV-1 Silicone Rubber 

RTV-1 silicone are one-component systems that cure when exposed to atmospheric moisture. There are 4 different technologies available with unique properties to suit a wide variety of applications. The material cures from the outside in, so it will skin over first and then cure through the silicone.

One-part room-temperature-vulcanizing (RTV-1) silicones are ready-to-use systems consisting of polysiloxane, a curing agent, fillers and additives. RTV-1 silicone are one-component systems that cure when exposed to atmospheric moisture. The material cures from the outside in, so it will skin over first and then cure through the silicone.

Depending on the nature of the crosslinker, small amounts of acetic acid, amine or neutral byproducts, such as alcohol, are released during vulcanization.

RTV-1 silicones are ideal for sealing, bonding and coating applications in nearly all industries, such as

1. Automotive
2. Construction
3. Electrical engineering
4. Electronics
5. Health care
6. Textiles
7. Household appliances

RTV-2 Silicone Rubber

RTV-2 silicones are two-component, Room Temperature Vulcanization silicone rubbers, gels or foams. Each part of the system comprises of either a crosslinker or a catalyst that will react when the two parts are mixed together to render the intended properties. There are two different types of crosslinking reactions: by condensation or by addition. Condensation curing requires an organotin catalyst and always releases byproducts. Addition curing requires a platinum catalyst and does not generate any byproduct. It can be customized to produce variable degrees of viscosity, adherence and mechanical, chemical or temperature resistance characteristics.

RTV-2 products feature a series of high-performance characteristics that, make them remarkably stable in a wide temperature range, with elastomers remaining flexible from -80°C to +250°C, with some able to overcome brief exposure to temperatures of 300°C. At the other end of the scale, some types of RTV-2 silicones can deal with drops of -100°C. They only break up at temperatures above 350°C, producing an inert silica deposit that is non-flammable and non-combustible.

RTV-2 is used in textile coating, mold making, release coating, 3D or additive printing, cockpit instruments, potting of engine electronics and gasketing, appliances, healthcare applications, lighting and electronics.

Advantages of RTV-2 over RTV-1

1. RTV-2 is available in a viscosity/hardness range varying from soft to medium, usually from 0 to 40 Shore A.
2. RTV-2 cures more rapidly
3. Crosslinking can be slightly accelerated by raising the ambient temperature
4. Curing of thick layers possible
5. Flowable, self-leveling or non-sag grades are available
6. Self-adhesive grades, with very good adhesion to a large range of substrates
7. Low shrinkage, no deformation, customizable hardness, resistance to high and low temperatures, acid and alkali.