Occasionally, we are asked about the adhesion of RTV-2 silicone to the surfaces of other materials, which is actually related to the type of materials being bonded. This article aims to clarify this confusion by discussing the basic knowledge of silicone and its bonding characteristics with other materials.
silicone adhesion
Basic Principle: RTV-2 silicone has good demolding properties, thus demonstrating low adhesion to most materials. Once liquid silicone cures, it becomes difficult to adhere to the surface of other substrates. Typically, silicone struggles to form strong bonds with non-specialized adhesive systems or pressure-sensitive adhesives (PSA). This is because the surface energy of cured liquid silicone is very low, making it difficult for other substances to adhere to silicone easily.
| Bonding Material | No Primer | With Prime | |
|---|---|---|---|
| Metal | Aluminum | C | A |
| Stainless Steel | C | A | |
| Copper | C | A | |
| Chromium | C | A | |
| Tin | C | A | |
| Soft Iron | C | A | |
| Plastic | Soft Vinyl Chloride Resin | C | C |
| Rigid Vinyl Chloride Resin | C | A | |
| Phenolic Resin | C | A | |
| Methacrylic Resin | C | A | |
| Polyethylene | C | C | |
| Ptfe Resin | C | C | |
| Rubber | Natural Rubber | C | A |
| Butyl Rubber | C | A | |
| Nitrile Rubber | C | A | |
| Silicone Rubber | C | A | |
| Glass | Glass | C-B | A |
| Ceramic | C-B | A | |
| Stone | Marble | C | A |
| Concrete | C | A | |
| Wood | Wood | C | A |
Explanation:
1. A indicates complete adhesion, forcibly pulling apart would result in breakage in the rubber layer.
2. B represents partial adhesion, forceful pulling may sometimes cause detachment.
3. C indicates no adhesion.
Solution: Achieving effective adhesion between RTV-2 silicone and other materials typically requires the use of specific primers. Types of primers may include reactive silanes or special organic silicone resins such as special acrylics. These primers are low-viscosity liquids that can be applied by brushing, spraying, or dipping. After solvent evaporation, the primer forms a thin film that cures at room temperature through atmospheric humidity or heating, enhancing adhesion between materials.
Precautions: Before applying liquid silicone by brushing or pouring, ensure that the primer has completely dried, as insufficiently dried primer can inhibit the curing of liquid silicone and weaken the bond.
