The silicone rubber material is an important basis for customizing silicone molds. Understanding the properties of silicone rubber is of great help to improve custom silicone mold manufacturing. Silicone rubber is a highly active adsorption material, which is an amorphous substance, which contains polysiloxane, silicone oil, white carbon black (silicon dioxide), coupling agent and filler, etc. The main component is silicon dioxide.
Various types of silicone rubber form different microporous structures due to different manufacturing methods. The chemical composition and physical structure of silicone rubber determine that it has many characteristics that are difficult to replace by other similar materials, including high-temperature resistance, chemical inertness, strong deformation resistance, etc.
Classification of silicone
The characteristics of silicone determine the type of silicone rubber. According to the composition, it can be divided into one-component and two-component silicone rubber. The vulcanization temperature can be divided into high-temperature vulcanization and room temperature vulcanization silicone rubber. The form of the product can be divided into liquid and solid silicone rubber. The vulcanization reaction can be divided into condensation reaction type, platinum addition reaction type, and peroxide curing type. According to the main chain structure, it can be divided into pure silicone rubber and modified silicone rubber. According to product characteristics, it can be divided into high and low-temperature resistant type, antistatic type, oil and solvent resistant type, conductive type, foam sponge type, high strength tear resistance type, flame retardant, and fireproof type, low compression deformation type, etc.
8 reasons why silicone is the best material for medical device design
- The silicon-oxygen backbone can provide excellent thermal stability
Silicone has excellent thermal stability, allowing the device to maintain key performance even after sterilization. Silicones can be sterilized by high-temperature steam sterilization, ethylene oxide sterilization (EtO), or gamma radiation.
- Silicone rubber is an inert material
Silicones are generally inert to bodily fluids and medications and have no odor. The chemical structure of silicones complies with USP Class VI and ISO 10993 standards.
- Silicone rubber does not contain plasticizers or other organic additives
Plasticizers or other organic additives can negatively affect the delivered drug and, if present, have the potential to migrate into the drug solution. Silicone, on the other hand, contains no additives such as plasticizers or organic additives.
- Silicone is durable
Silicone has good elasticity and recovery after a puncture to reduce material fatigue. These key properties give the silicone a long service life, even under dynamic stress. This factor can greatly affect custom silicone mold making.
- Silicone has a low modulus
Silicone requires minimal insertion force to improve the smooth operation of the device – or easier assembly when combined with other components.
- Silicone can be formulated into various hardnesses
Silicone can be molded to a variety of hardnesses to accommodate either too hard or too soft materials, increasing the potential for improved ergonomics and comfort.
- Silicone has a good design aesthetic
Many silicone elastomers are inherently transparent and readily colorable.
- Silicone is easy to process
In addition to the comfort of hardness and aesthetics, silicone also offers a range of customization options. Materials can be applied to a variety of devices and designs, from infusion-type catheters to incision valves to breathing masks and more. Other customizable options include tensile strength, coefficient of friction, cure time, and elongation.
How do the properties of silicone rubber affect custom silicone mold manufacturing?
The custom silicone molding process is mainly a production process formed by pressing molds in related machines, such as the production of silicone mobile phone cases, silicone ice trays, etc. The main production process is the silicone processing of silicone raw materials or rubber raw materials that are formed into products by heating and pressurizing in a closed mold cavity. Usually, the raw materials are uniformly mixed into a mixed rubber through a mixer, and the mold is moved into the vulcanization molding machine. Then the mold is closed and pressurized to form and solidify or vulcanize, and then de-molded to obtain silicone products. This process is suitable for the processing of thermosetting materials.
Silicone processing technology
- Injection
This is a highly technical process through which we can achieve the combination of silicone and plastic. Its products show good thermal stability, cold resistance, excellent electrical insulation properties, and no toxic substances are produced when burning.
2. Extrusion
In extrusion molding, extruded silicone products are usually formed by extruding silicone rubber through an extrusion machine. Generally, the shape of extruded silicone rubber is long, and the tubular shape can be cut at will. The shape of the extruded products are relatively simple, mostly strips. . Silicone tubes are widely used in the fields of medical and mechanical equipment. It can also be used as a buffer in the packaging material.
3. Calendering
The silicone rubber is kneaded and kneaded by adding silicone, silicone oil, etc. to make a mixed rubber, and then the sheet is calendered. The film produced by calendering has obvious differences in physical and mechanical properties in the longitudinal direction and the transverse direction. This phenomenon is called the calendering effect. In particular, the longitudinal tensile strength of the film is greater than the transverse direction, the transverse elongation at the break of the film is greater than that in the longitudinal direction, and the longitudinal shrinkage rate of the film is greater than that in the direction. The calendering effect is the result of the orientation of macromolecules and needle-like and flake-like compounds in the rubber compound along the calendering direction during the calendering process. The size of the calendering effect is related to the composition of the rubber compound, the calendering temperature, the speed, and the speed ratio.
4. Perfusion
The operation method of filling or pouring mold: pouring mold or pouring mold is used for relatively smooth or simple products, no mold line saves manpower and time, i.e. the product or model you want to reproduce is surrounded by rubber or glass plates, through vacuum pump The outgoing silicone rubber is poured directly into the product. After the silicone rubber is dried and formed, the product is taken out to form a mold. It belongs to the solid-liquid combination and is used in mobile phone sets, luggage sets, and other products.
5. Coating
Fast vulcanization; strong adhesion; good fluidity and easy defoaming. The catalyst of the platinum complex is non-toxic and tasteless and has good air permeability, heat resistance, and certain tensile strength after molding (use temperature -60℃～200℃). Excellent non-slip properties; no pollution; low hardness; strong adhesion. High tear; high transparency; good tensile properties. Wear resistance, washing resistance, high-temperature resistance; high three-dimensional level, smooth, soft, good elasticity. Resistant to water washing and dry cleaning. Suitable for fabrics, with anti-aging effects, such as silicone gloves, rain boots, etc.
Application of Silicone in Medical Devices
Certain devices that come into contact with the skin:
(1) Respiratory mask: especially the mask that needs to be worn for a long time.
(2) Silicone rubber is a skin-friendly material with absolutely no negative effects on the skin. Therefore, Momentive Silicone Rubber is an excellent choice for foam applications, scar patches, etc.
Devices that come into contact with human orifices:
Laryngeal mask: In contact with the trachea, the silicone is soft and strong to keep the airway open.
Catheter: Silicone support produces a soft tube body, as well as a high tensile strength balloon.
Devices that come into contact with human blood and body fluids:
The catheter of the infusion device: such as the peristaltic pump tube of the infusion pump, the outer tube of the insertion type catheter.
Parts of infusion equipment: such as rubber plugs for needleless connectors, O-rings for kidney dialysis filters, etc.
Rubber plugs and hemostatic valves in various medical consumables that come into contact with medicinal liquids.
Silicone rubber has a large application scenario. You can see silicone rubber in various medical equipment, biopharmaceuticals, vaccine research and development, interventional therapy devices, etc. Through countless scientific facts, we can conclude that all custom silicone mold related products must be optimized according to the properties of silicone rubber.NEWTOP has reliable custom silicone mold manufacturing and custom silicone product manufacturing capabilities to meet any needs of customers. Contact our team of engineers today for more information.