RTV2 Mold Silicone and Its Applications

RTV stands for "Room Temperature Vulcanizing" in English. Its Turkish equivalent means "Curing (Setting) at Room Temperature." RTV is the common name given worldwide to silicones that cure at room temperature. The "2" in the RTV2 designation signifies that the substance has a two-component chemical structure. The term "Vulcanizing" in Room Temperature Vulcanizing means "Curing" and "Setting" in Turkish. Curing is a term that refers to the hardening of a polymer material through cross-linking of polymer chains, provided by electron beams, temperature, or chemical additives. polymer In short, curing is a process in which a chemical reaction or physical effect occurs, resulting in a harder or more stable bond (such as an adhesive bond) or substance (such as concrete). RTV2 mold silicone is an indispensable material in industries where molding is used. Due to its technical properties, it is a production material that facilitates manufacturing and has many advantages in terms of cost and quality. Due to its variety of applications and flexibility, it is widely used in many sectors from food to construction. In addition to copying models, it is also used for transfer printing or coating processes. Depending on the requirements of the model, the silicone to be used must have different degrees of flexibility and softness. The hardness of silicone is indicated by the "Shore A" value. In RTV2 silicones, as the shore value increases, softness/flexibility decreases. As the shore value decreases, softness/flexibility increases. Selecting the appropriate Shore value according to the model's dimensions, details, and the casting material used is very important. Consisting of base material and catalyst (hardener), RTV2 mold silicone is divided into two types: Addition Cure and Condensation Cure. These are examined in detail in separate sections in our article.  

Addition Cure RTV2

Addition Cure RTV2 silicone is prepared with a mixture of component A and component B. Depending on your environment, it cures at room temperature or can cure faster when heated. Addition Cure RTV2 silicones with different softness/hardness values can have complete transparency and zero shrinkage properties, as well as hypoallergenic properties. In applications where dimensions are critical, it is preferred in molds and industrial material production due to its low or zero shrinkage ratio. The main applications of Addition Cure RTV2 silicones include: mold making suitable for food contact, molds for human skin, medical products, prototype applications, hyperelastic sculpture making, plastic makeup applications, transfer printing, electronic coating, mold making used in jewelry, cultured stone, automotive spare parts manufacturing, and similar fields.  

Condensation Cure RTV2

Condensation Cure RTV2 silicones cure with tin-based catalysts. The ideal setting time for Condensation Cure silicone should be in the 8-10 hour range, depending on ambient conditions (humidity level and temperature). If this time is too short or too long, there will be a reduction in the silicone's strength and performance. However, if needed, this time can be shortened or extended by changing the catalyst application rate/amount or ambient conditions. Due to high casting numbers, the ability to capture all details of the surface from which the mold will be taken, high durability, quick curing, and ease of use, it is one of the most preferred mold materials. Condensation Cure RTV2 silicones also show variations depending on their applications and have different softness and hardness values. Their main applications include: furniture and interior decoration accessories, shoe soles, vitreous ware, cultured stone, planters, gift items, art, soap, candles, scented stones and similar hobby molds, and button manufacturing in many fields.  

Use of Thixotropic Agent in RTV2 Mold Silicone

Thixotropic agent stands for "Thixotropic Thickening Agent" in English. In our country, it is known as a "consistency enhancer." The purpose of using thixotropic agent is to make flowing silicone denser and less fluid. This provides ease of use by reducing the fluidity of the silicone when taking molds of vertical or fixed models. To take a mold of an object or surface, the RTV2 silicone mixture and thixotropic agent that you have prepared should be applied to the outside of the model. This process can be applied by hand brushing, or with the help of a brush or spatula. In such cases, the thixotropic agent reduces the fluidity of the silicone, provides savings through the use of less silicone, and since it does not alter the structure of the silicone, it makes it possible to mold the finest details.

What Are the Properties of RTV2?

RTV2 mold silicone is used in mold making in different hardnesses. The appropriate softness/hardness value is selected according to the casting material to be used in the product to be manufactured and the structure of the model. The properties sought in RTV2 silicone are as follows: • High resistance to tearing and ripping, • High heat resistance, • Chemical and mechanical strength, • Zero or low shrinkage ratio, • Low viscosity (high fluidity) and reaching all points of the mold, • Easy air bubble release, • Flexible curing time, • Non-adhesion to surface and model, • Long operation time, • High casting numbers, • Hypoallergenic product that can be used in many areas such as food and medical, • Compatibility with many casting materials such as epoxy, polyurethane, polyester, paraffin, stone powder/concrete.  

It Is Possible to Reduce Production Costs with RTV2

Around the world, costs continue to rise due to supply problems in production, rising energy prices, and currency fluctuations. In this situation, the quality and durability of raw materials entering production becomes more critical. Silicones, which are the most stable and efficient polymers found, stand out from their alternatives with superior reliability and extended service life. Room temperature curing silicones also eliminate the heating costs required by polymers that harden in an oven. Curing times can be adjusted to provide flexibility in production line usage. Many RTV2 formulations provide more efficient mold release performance than cured rubbers have for organic and inorganic materials. Molding, printing, and prototyping applications are ideal materials. By using correct methods and appropriate amounts of additives, they can be used repeatedly and thus contribute to production economy.   Gökhan Benli Managing Partner Craft Yapı