PAD PRINTING INKS

Pad printing ink for the perfect print! The Natron™ Series pad printing inks are formulated to work with all pad printing machines. These Boston Industrial Solutions inks achieve outstanding results on all difficult to print substrates. They are available across all industries around the world.
 
In addition, our customer care provides guidance to help you find the perfect ink for your application. We offer solvent-based inks, UV-based inks, and water-based inks. Each of our ink series is rigorously tested to provide the highest quality, opacity, and best adhesion for any substrate. The Natron™ inks are formulated with the highest quality management standards. These inks meet and exceed safety, environmental, and functionality standards. For more information about the Natron™ Ink series, check out our pad printing inks.
High opacity silicone inks

WHAT IS PAD PRINTING?

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.

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PAD PRINTING INK

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.

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pad printing ink for silicone
pad printing ink solvent

PAD PRINTING SOLVENT

  • The Natron ink series has:
    – Solvent-based pad printing inks
    – UV-curable pad printing inks, and
    – Water-based pad printing inks

    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.  

PAD PRINTING HARDENER

Pad printing hardener is an additive for pad printing ink. The hardener is also referred to as a catalyst or cross-linker. The function of the hardener is to improve the inks physical characteristics. These include resistance properties, such as ink adhesion and resistance to abrasion, chemicals, heat, water, and block.
 
Crosslinking implies the linking of different molecules. It increases the molecular weight of the ink film layer through a chemical reaction between the crosslinking additive and the resin binder.
The crosslinking occurs within the ink layer as well as between binder and substrate.
 
The hardener is not only responsible for adhesion and physical resistance, but it is also responsible for enhancing the printed image. Like with our solvents, different hardeners work with different ink series. Also different applications require different ink-to-hardener ratio. This can vary from 0% (not adding hardener at all) to adding up to 25% of the inks weight. Note; that the hardener reduces the pot life of the ink. The higher the hardener ratio, the lower the inks pot-life.
silicone ink for printing silicone rubber - Natron SE Series - Boston Industrial Solutions

PAD PRINTING SILICONE INK

Pad printing silicone ink is a specialty ink for printing onto silicone rubber substrates. Silicone rubber is a difficult substrate for ink to adhere to. As a result, only a silicone based ink will adhere onto silicone. Like pad printing ink for glass, silicone ink requires heat to cure. We offer the Natron™ SE Series, DC Series, the SE-F Series for medical applications. All these silicone inks are great options for decorating silicone rubber products.
 
The SE Series has the highest opacity and great printing pad release compared to any other inks in the world. It comes in over 40 standard colors, including the hyper colors. The SE Series is the world standard, the the yardstick for printing on silicone. All Natron™ silicone inks have excellent chemical resistance, scratching, bending, stretching. They also meet and exceed compliance, sustainability, regulations, and mil spec standards.
 
To pad print with silicone, you need our propriety pad printing solvents for silicone. These are TXM and SF Silicone solvents.

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WHICH PAD PRINTING INK SHOULD I USE?

To find the correct ink, you need to first understand the composition of your substrate. Some substrates are obvious as to their composition, e.g. glass, metal, and plastics. Other substrates such as silicone are not. As a result, it is important to test the part prior to selecting the ink to use. If you are not sure, call us to help you figure out your substrate composition.
 
Ink adhesion testing should be done before a production run. This will help determine the correct in and hence reduce wastage. Ink adhesion is affected by dirty / oily surfaces. Make sure the substrate is clean before adhesion testing and mass printing.
 
Lastly, we should take into consideration abrasion, chemical, and weather elements testing.
Natron™ ST tagless printing ink
Volta™ M150 1-Color pad printer

HOW LONG DOES IT TAKE TO DRY AND CURE THE INK?

Printing ink could be dry but not cured. Dry ink means that the solvent has evaporated but the cross-linking has not taken place. Cured ink means that cross-linking has taken place. It is at this point that adhesion testing should be done.
 
 
Typically, perform adhesion testing 18 – 36 hours after printing. This wait time makes sure that the ink has achieved some cross-linking with the substrate. In some cases the printed product can take up to 6 days to achieve full cure.

Over a period of time, the hardener continues to harden. To reduce drying time and cure time, use heat. It should take 10 – 15 minutes to finish drying the ink. Heat does two things. It makes the solvent evaporate fast and speeds up the chemical reaction.
Note, when using the heat, you should let the part to cool down – wait for 30 minute before doing adhesion testing.

COLOR MATCHING PAD PRINTING INK

Color-matching is a process of mixing several colors to produce a new color. It involves copying a color from a known standard or target. In pad printing we use Pantone color system. We can however create colors from RAL and Hex systems. RAL is a type of color matching system. It is mainly used for the purpose of paintings and powder coatings. Pantone (PMS) is mainly used by graphic designers for color graphic printing.
 
At Boston Industrial Solutions we can use a wet sample or a customer’s specified PMS number. Alternatively, customers can send in specific substrate.
 
We use our in house developed AI to accurately determine the exact customer color. Using these ratios, then we formulate the exact color match for our customers. Out in house developed AI uses weight to mix the colors. All color formulation created are stored for future and repeat customer orders.
silicone ink color matching - silicone ink - boston industrial solutions
Natron SE Series Silicone Inks - USP MEM Elution Cytotoxicity Test - Certification - Boston Industrial Solutions

PRINTING INK COMPLIANCE, CERTIFICATIONS, AND SPECIFICATIONS

Different pad printing applications require different ink compliance, certifications, and specifications. Compliance basically ensures that a pad printing ink or a screen printing inks meet or exceed the final users specifications and certifications.
Ink certifications allows ink suppliers, such as pad printing, screen, ink jet, etc., to evaluate inks for use with specific label materials and conditions of acceptability.
 
An example of compliance it the CPSIA, which imposed testing requirements printing inks. This standard creates acceptable levels for several substances common in most consumer products, especially those designed for children, ages 0-12. It imposes restrictions on phthalates and lead. In addition, it imposes compulsory third-party testing by accredited laboratories specifically for lead. All Natron inks are heavy metals and phthalates free.
 
Specifications are requirements by the end user that pad printing inks have be of specific characteristics and meet certain standards. Example, Military (MIL-Spec) / Aerospace Qualified Ink – Military spec to MIL-I-43553 and AA56032. When properly applied and cured, the ink has excellent adhesion to metal, glass, and hard plastics. The ink is resistant to acids, alkalies, solvents, salt spray, thermal shock. The Natron MG Series ink for screen and pad printing on glass, metals, ceramics, and hard plastics is qualified to meet Military spec to MIL-I-43553 and AA56032.
 
The MG Screen printing and pad printing ink is a permanent, two component, epoxy-based, printing ink. This ink is designed to be used with a catalyst (hardener) i-240x, which cure at elevated and/or at room temperatures.
 
For room temperature cure, perform adhesion testing 18 – 36 hours after printing. This wait time enables the ink to cross-link to the substrate. In some cases the printed product can take up to 6 days to achieve full cure.

 

To reduce drying and cure time, use heat. It should take 10 – 15 minutes to flash off solvents and dry the ink as well as speed up the chemical reaction.
 

CHOOSING THE RIGHT PAD PRINTING INK

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.

Volta™ M150 1-Color pad printer

UNTREATED POLYPROPYLENE PAD PRINTING INK

The Natron™ UP Series is a specialty 1 or 2-component pad printing ink formulated for printing onto untreated polypropylene (PP).  This fast drying inks, exhibits high gloss, and is able to print on untreated polypropylene (PP). The product does not have to be pre-treated prior to printing. However, it is important to make sure that the substrate is clean – free from hand oils, etc.
 
In additional this ink works very well on treated polypropylene, treated polyester, lacquered surfaces, and polyurethane.
 
For superior adhesion and out door applications, use the i-300x hardener. The use of the hardener increases gives this pad printing ink for untreated polypropylene exceptional abrasion resistance and extended pot life. Like all of our other Natron Pad printing inks, this series is classified as NT (non-toxic) and is formulated with pigments which are free from heavy metals.