Pad printing process is used to transfer a two dimension (2-D) image onto a three dimension (3-D) object. This printing process uses a silicone pad to transfer an image from a printing plate (cliché) onto the object or substrate. Whether you’re printing onto glass, silicone rubber, mugs, tumblers, fidget spinners, pens, industrial printing applications, there is an ink that’s right for every substrate.
This method of printing has gained popularity for printing onto difficult to print odd, shaped objects. To print, an image is required. This image is etched onto a printing plate (cliché). It is this image that is transferred to an object or the part to be printed.
Next a cup is filled with printing ink. The cup which has a scrapping ceramic ring floods the image and removes the excess ink from the image. Then, a printing pad made of silicone picks up the image and transfers it onto the object. All these parts must be properly configured on the pad printing machine.
The pad printing cycle: The ink cup moves across the etched cliché and fills the etch with the printing ink. The carbide or ceramic ring then removes the excess ink from the etch. The silicone pad then presses down onto the ink, picks it up, and transfers the image onto the substrate. Now, the 2D image that was etched into the plate is featured as artwork on a 3D product.
Note: for every new design, a new plate must be made. Additionally, for every color added into the design, a new plate must be etched. For example, a 2-color logo would require 2 plates, a 3 color logo requires 3 pad printing plates to be etched.
Boston Industrial Solutions, Inc. manufactures and provides the best pad printing inks for any application. Our Natron™ Pad printing inks are used to print on a wide range of challenging surfaces with exceptional quality, performance, and ease.
Like all any other Pad printing ink, the Natron series inks are made of binders, resins, solvents, and pigments. But, unlike any other inks, we use chemistry combined with AI to select the finest ingredients, fine tune, and enhance the inks. It is for this reason our inks are suitable for a wide range of applications from silicone, to metal, to rubber, plastics both treated and untreated plastics.
Additionally, these inks are made with the environment, sustainability, and compliance (non-toixic) in mind.
The Natron™ pad printing inks are either 1-or 2-component inks. The 1-component ink means; an ink that only needs to be mixed with one component e.g. solvent. In general, the range of solvent usage ranges from 10 – 25% depending on the ink series. On the other hand, A 2-component ink requires a hardener in addition to the solvent.
There are different ratios of hardener needed depending on the type of ink. Typically 10% of the inks weight of the ink should be added to the ink. A higher hardener ratio reduces the inks flexibility. Pad printing silicone inks use a catalyst instead of a hardener. The catalyst is used to vulcanize silicone. For silicone pad printing ink, the higher the catalyst, the faster the drying of the ink. Unlike hardener, the catalyst does not affect inks flexibility, it only affects the inks cross-linking capability. These in additives are vital for getting the perfect print.
All these inks require a solvent additive for printing. The pad printing solvent is used to alter the viscosity of the ink and change the speed at which the ink dries. There are several types of pad printing solvents rated by their evaporation rates. The evaporation rate is commonly known as the “speed” of the thinner.
To simplify pad printing process, we formulate our inks to use similar solvents. This is cost effective way to speed up pad printing professional’s job.
Solvents evaporate out of the ink after pad printing. Only solids are left behind. Immediately during printing, the solvent evaporates out of the ink mixture, making the ink tacky. This enables the ink to be released from the silicone pad onto the substrate. We have several types of solvents formulated to satisfy the desired ink evaporation rate. To effectively print, please select the correct solvent for your ink series.
Choosing the right pad printing ink is key to successfully complete a pad printing job. To buy the right printing ink you ought to consider several factors. But first, let us explore the components of pad printing ink.
Printing ink components:
• Ink pigment: Usually in powder form. The pigment give the ink color and controls inks opacity. Opacity is determined by the amount of pigment used.
• Resin: Resin is critical to the functionality of an ink. It impacts inks characteristics of a finished ink. This includes gloss, adhesion, ink flow, and can also help disperse pigment.
• Solvent: Used as the dissolve vehicle for resin and the pigment. The solvent also controls the inks viscosity and aids to transport and drying of the ink. The solvent eventually evaporates, leaving the inks solids as the print. The solvent is also added during printing to alter inks viscosity. The speed of the added solvent additionally impacts inks pot-life.
With that in mind, lets discuss how to choose the correct ink for a substrate.
Step 1: Determine the substrate. Prior to printing, understanding and knowing the substrate is the most important factor. This will determine which type of ink to use. Different inks adhere onto different substrates. Choosing the wrong ink will almost certainly guarantee a filed print.
Step 2: Determining resistance (Chemical and abrasion) and specifications. Different products get used for different applications and environments. A printed product will need to withstand the products use specifications. For example, if a product must withstand abrasion resistance, the ink must meet this requirement. If an ink will be cleaned with alcohol, then ink used must withstand this. Pad ink for glass must withstand dishwasher, hot-water, and detergents. Mil-spec prints must use Mil-spec inks. Tagless pad printing inks must pass Oeko tex and RSL certifications. Therefore, it is important to determine the type of resistance and specifications for the printed product.
Step 3: Finish type is another important factor to consider when choosing an ink. Some applications call for matte finish, while other call for a glossy finish. The SE silicone inks have a high gloss finish. This is not the case with ST Series inks for soft touch which have a matte finish. On the other hand, MG screen and pad printing inks can be altered from gloss to satin to matte finish.
Step 4: Determine the cure and drying speed. This is important because it determines the through put. Air cure inks once printed can be packaged or stacked immediately after pad printing. Heat cure pad printing inks require heat to dry and cure. For example, glass pad printing ink and silicone pad printing ink lines must be cured with heat.
Step 5: Type of applications. Medical grade, food-grade, mil-spec, industrial grade, child safe inks etc. Pad printing ink must pass the specified application. Medial and food grade inks must pass all restrictions. It is important to use compliant inks that are free from heavy metals and forbidden chemicals. Boston Industrial Solutions manufactures Non-toxic pad printing inks for all applications.
Step 6: (Optional). This step is for “specialized applications” e.g., silicone, nitrile, neoprene. These rubbers are considered specialized products. Only Boston Industrial Solutions pad printing inks are formulated for these specialized applications. Ink for printing on silicone must be flexible.