Silicone is a manmade material, not to be confused with Silicon, which is a naturally occurring chemical element. The chemical composition of silicone makes it more heat resistant and durable than other types of elastomers. Since silicone is inorganic and most rubber is organic, it is more resistant to naturally occurring fungi, ozone, and UV light.
Silicone is typically available in a liquid or gel form. Before silicone can be converted into a solid form, it must be cured or vulcanized. The liquid is first poured into the desired shape with injection molding. There are many different molds for silicone pads, but a few very common shapes with pad printing. Custom molding can be made for the best pad printing results on your products. Sometimes, fillers can be added in order to enhance certain properties or to reduce cost. Special grades of silicone rubber include steam resistant, high tear strength, electrically conductive, and flame-retardant silicone. The properties of silicone have made it desirable in a wide variety of industries from automobiles to electronics to medical devices.
Silicone exhibits many useful characteristics, including:
· Highly inert, low chemical reactivity
· Non-toxic
· Resistant to extreme environments and temperatures (−148 to 572 °F) *
· Does not stick to many substrates, but adheres very well to others, e.g. glass
· Does not support microbiological growth
· Resistance to oxygen, ozone, and UV light
· Electrical insulation properties
· Fire retardant
· Biocompatible
· Hypoallergenic
*While still maintaining its useful properties
All pad printing pads are made of silicone. Silicone is the ideal material for pad printing pads as it is a non-stick substance. In other words, not much sticks to silicone other than silicone. This becomes tricky when pad printing on silicone. Read more about pad printing on silicone and The Idiosyncrasies of Printing Silicone Products. Other than the ease of the silicone printing pad to pick up and transfer the ink without sticking, the flexibility of the pad makes it extremely versatile. Not only does this allow you to pad print on any substrate, you can also pad print on almost any shape object. The flexibility of the pad allows it to conform to the shape of the product whether it be a pen, golf ball, or USB flash drive. Depending on the product you are printing on, the type and hardness of the silicone printing pads will vary.
Silicone printing pads will stick to the mold, mainly styrene molds, urethane molds, and epoxy molds. If the pad has a larger volume of oil it becomes soft, and it must have a longer period of curing time. For instance, if you are curing a 30-durometer pad in the oven the normal bake time would be 2 hours. However, a 3-hour bake time would be more sufficient to ensure the pad does not stick to the mold. Also, turning up the oven temperature from 150°F to 175°F will help guarantee a perfect cure. A device called a Shore durometer measures the resistance to indentation, or hardness, of a material, typically of polymers, elastomers, and rubbers. Silicone rubber can be manufactured anywhere between 10 and 100 durometers. Silicone printing pads typically have a durometer between 35-80. The higher the number, the harder the material. For instance, if you want to print on a lightbulb, you need a pad that is about 30 durometers. On the other hand, if you want to print on a bowling ball, you need a much harder pad with a durometer around 80.
Silicone printing pads are one of the most important components of a pad printing machine. Without a proper pad, you run the risk of a misprint or even breaking the product.
Inkcups is your partner who understands the fast-paced nature of your business and the importance of product quality. For hundreds of companies, we provide the turnkey solution for all pad printing supplies from mixing sticks to pads to laser plate-makers. If you have any questions or inquiries, please call Inkcups at 1-978-646-8980 or contact us.
Additional Resources:
Pad Printing Pads Overview
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