Tag Archive: thinner

  1. Ink Adhesion Part 3: Ink Mixing, Contamination, Blooming and Mold Release Agents

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    Ink Adhesion Part 3: Ink Mixing, Contamination, Blooming and Mold Release AgentsBefore printing on any parts there are several factors which are of vital importance: ink mixing, product cleanliness and substrate additives. Regardless of proper ink preparation and chemistry, surface contamination, blooming and mold release agents may all interfere with your ability to achieve satisfactory adhesion.

    The two most important factors that must be addressed when dealing with ink mixing are: How are you mixing the ink? What components are you using? Inks are formulated to be mixed at specific ratios, and any deviation may result in adhesion failure. You must choose the correct ink and mix it to the exact manufacturer specifications. It is a common misconception that adding hardener over manufacturing specifications will allow for better adhesion.

    Surface contamination is a huge factor in whether or not the ink will adhere to any given object. The first reason contamination may occur is because people are not handling the object correctly. Oils on the handler’s hands can be transferred onto the objects. Contamination can also occur as a result of secondary processes being performed on the parts. For instance, if you choose to wash the objects with a detergent, this may leave a residue behind on the object and the ink may not adhere properly. Here at EPS we use alcohol. This is a standard solution which readily flashes off and is used to wipe the parts of any dust, oils or any contaminants before printing. With proper handling, cleaning the parts may be unnecessary, but wiping with alcohol does assure that there will be a clean surface to print on.

    Blooming is a term used in the plastic industry and it denotes a plasticizer or other additive coming to the surface of a part over time. The difficulty with this contamination is that you can wipe the surface of the part free of contaminates but over time the part will re-bloom and the contaminants will interfere with the bond between the ink and the parts.

    Mold release agents (also known as de-molding agent, form oil, parting agent or release) are substances used in molding and casting that aid in the separation of a mold from the material being molded and reduce imperfections in the surface. While these additives make the plastic manufacturing process simpler, they can wreak havoc on attempts to achieve adhesion.

    In the end, experience is the best weapon in attaining adhesion. If you have any questions or concerns please contact Technical Service.  For more information about Engineered Printing Solutions’ custom solutions, standard pad printers, industrial digital ink jet, consumables and other auxiliary equipment, email sales@epsvt.com or call 1-800-272-7764.

  2. Ink Adhesion Part 2: Bi Component, Pre-Treatment and Post Cure

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    Have you ever looked on the back of an object and seen the recycle symbol? It tells you what material the object is made of. When it comes to plastics, Polypropylene and Polyethylene are considered the two of the most difficult materials to get ink to adhere to due to their relatively low surface energy. Polypropylene is used to make a wide variety of items and low and high density Polyethylene is commonly used in food packaging. When it comes to these difficult substrates it becomes necessary to pre-treat to affect a change in surface energy to make the surface amenable to bonding with – or cross-linking – with the ink.  This causes the substrate surface to become more receptive.

    The most commonly used methods of pre-treatment are:

    • Plasma and Corona: Electricity applied to the surface.
    • Flamer: Liquid propane (LP) or natural gas. With Flamer there may be variation due to cleanliness of the burn and how the flame will pre-treat any given substrate.
    • Chemical Pre-Treatment: Usually manually applied with a liquid soaked rag.

    Unfortunately on any given substrate you cannot assume that you will affect an equivalent change in the surface energy from one pre-treatment to another. Finding the correct ink pre-treatment may consist of 3 different segments: cleaning, activation and surface bonding.

    Plasma surface treatment is a process that raises the surface energy of various materials in order to improve the bonding characteristics when ink is applied. Plasma is used widely in the medical industry. This is because you don’t have the bi-product of the other 2 pre-treatments such as carbon from the flaming process or residual VOC’s left behind from the from the flashing process of a chemical pre-treatment. Corona treatment is commonly used on materials such as polymers, papers, films, glass and metals.

    Plasma is a good option for components that require a longer treatment hold. Some of the key advantages include: surface chemistry and 3 dimensional treatments. Corona is another form of plasma that can be used with in-line processes. When working with corona the systems are easy to maintain and user friendly.

    Flame pre-treatment can also be integrated into inline processes, and require careful and sometimes precise setup in order to be safe and effective. Proper air to gas ratios, flame intensity and dwell time all play into successful pre-treating. Flame plasma systems combine compressed air and a flammable gas which is combusted to create a flame. One advantage is that the material surface only has to be exposed to the flame for a brief period of time to become polarized through oxidation. One setback is the heat level required for this treatment may cause damage to the parts.

    Chemical priming is yet another way to pre-treat difficult to adhere to substrates and is generally considered a last resort due to the generally manual nature of application. Essentially primers are used to chemically modify the surface by removing contaminants, adding reactive sites for bonding and increasing surface energy. One disadvantage is that these primers often contain chlorinated solvents that are considered volatile organic contents.

    Many substrates will require pre-treatment to satisfy customer’s individual requirements for print longevity. But with the correct treatment and testing, our technical service technicians will test the inks and provide samples for the individual customer’s review.

    For information about Engineered Printing Solutions’  custom solutions, standard pad printers, industrial digital ink jet, consumables and other auxiliary equipment, visit Ink Adhesion Part 3: Ink Mixing, Contamination, Blooming and Mold Release Agents, email sales@epsvt.com or call
    1-800-272-7764.

  3. Ink Adhesion Part 1: General Education

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    Have you ever looked down at a water bottle and wondered how the logo got there? Personally I know I have. Before the colors and image can get put together on the object the first question that needs to be answered is how to choose the right ink for the job. Simply put, ink adhesion is ink that sticks to any given product to a known specification. One of the most common tasks our Technical Service team are charged with is to “find me an ink that sticks to the surface of my product.” It wouldn’t be realistic if I told you that our Technical Service team has magic powers and can automatically determine the perfect ink for the material being printed on. Even though inks are produced to stick to a particular substrate; the question is which ink is best suited to adhere to your particular substrate based on your requirements?

    There are many different substrates and even more sub-sets within each . Not all polypropylene’s (PP), for example, are created equal. An ink that may exhibit flawless adhesion to one PP product may not adhere at all to another. We therefore need to match the ink series with the particular substrate being presented. However if you supply our Technical Service team with the parts you wish to print on, they will be able to begin working their “magic”. They will be able to first make an educated guess as to which ink will meet the customers’ expectations based on experience, then begin testing the inks and provide samples for the individual customer’s review.

    For information about Pad Print Machinery of Vermont’s custom solutions, standard pad printers, industrial digital ink jet, consumables and other auxiliary equipment, visit Engineered Printing Solutions, email sales@www.epsvt.com or call 1-800-272-7764.

  4. Safe and Efficient: Best Print Environment Ever!

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    To get the most out of your printing operation, you need to account for many factors, including lighting, adequate compressed air supply, controlled temperature and humidity, quality consumables, etc. Everything of value in your operation must be put in place, maintained, serviced and supplied. One factor often overlooked is the operator, and more pertinent to this discussion, operator ergonomics.

    An operator who exerts as little energy as possible per print cycle and who has everything needed to complete the assignment within the production cell will deliver consistent and predictable productivity throughout the shift. Additionally, job satisfaction and, most importantly, safety will impact your company’s throughput and profit. Never dispute the value of a happy employee.

    Ergonomics
    When designing your operator’s production cell, keep in mind the following to improve working conditions:

    • The distance / height of reach for an item
    • Comfortable seating
    • Proper floor mats, also known as anti-fatigue mats.
    • Temperature and humidity control in the work environment including heat exhaust from nearby heaters or dryers.
    • Rotations within shifts. This prevents repetitive stress disorders and boredom.  It also ensures crew flexibility and increases the employee’s perception of value to the operation, putting the emphasis on the importance of production.
    • The right tool for the right job. Avoid cheap multi-tools with every hex-key ever made. Our pad printing equipment should not require the use of more than 4 hex-keys.

    Safety
    As mentioned above, safety will most definitely impact your bottom line. OSHA provides an interactive program on their website called $afety Pays  to help determine the financial impact of injuries. This number can be used when calculating ROI of safety equipment.

    • Always hang cables and hoses from the ceiling; never lay them on the ground.
    • Wear gloves, goggles, and aprons.
    • Do not disable safety features on machines. They are installed for a reason.
    • Keep pallets out of the way. If possible, keep pallets out of the production area completely. Moving an empty pallet around creates extra work and aching backs.
    • Fixtures should be designed carefully to ensure fingers stay out of way of the pad.
    • Take the time to properly train every production member on how to lift with their knees. On-the-job training means it is a requirement of the job.

    Preparation
    Try always to be proactive instead of reactive. For example, instead of requesting or preparing ink during the changeover time, someone should have the ink ready for the operator before the job begins. Any way you can keep the printer printing will improve your up-time.

    • Keep all thinners and other supplies available at the production cell.
    • Keep a supply of cleaning materials at the production cell.
    • Use outside help for non-printing tasks, like handling boxes, proofing jobs, work orders, removing pallets, etc.
    • Printing can be a bottleneck. Exploit it by keeping the printer printing.

    Job Satisfaction
    A happy employee is a productive employee. Think about it. If your employees are frustrated about working conditions, they are distracted from their job.

    • The less your operator deals with job frustrations and physical fatigue, the more printing cycles will take place.
    • Removing frustrations and dangers from your operator allows more commitment to quality, service, and exceeding production goals, resulting in …
    • The best print environment ever!

    Need Help?
    PPMOVT’s Sales Engineers are really smart! Why not use them? They’ll help you figure out the holes in your operation and recommend ways to plug up productivity drains.  Call us at 1-800-272-7764, or use Live Chat on our Home page https://www.padprintmachinery.com

    Then we can add your business to the list of best print environments ever!

  5. Save on Pad Printing Ink!

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    Our customers have told us many times how frustrated they are with the amount of pad printing ink they have to throw out at the end of the day. Well we heard you and designed a handy little device to help utilize those small volumes of the ink mixed in the cups. Plus when the ink volume is less than 25 grams, the print quality can deteriorate – not with the new Ink Saver-Ring!

    The Ink Saver-Ring fits into a sealed ink cup where it agitates the ink as the cup slides across the cliché. This is a great tool for pad printers who use bi-component inks that must be throw out at the end of the day. Plus this ring will also help prevent the ink pigments from settling in the cups. Over time, less ink waste will add up to a significant cost savings!

    Available for all sealed ink cup sizes, call us for pricing and click Ceramic Ring Cups for details.

  6. Ink Viscosity and Seasonal Adjustments

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    Pad printing is a thin film process. It starts with an etch depth in the cliché of approx. 25-75 microns and only a fraction of that ink film is picked up by the pad. Of the wet ink, 50% is a solvent that evaporates leaving only a 5 micron dry ink deposit. You can easily see why such a thin ink film is so susceptible to changing temperatures, humidity levels, static charges and even variations in airflow. Listed below are the ways you can control the ink viscosity and seasonal adjustments.

    Control the rate that solvents evaporate from the ink
    • Solvents evaporate too slowly
    – The surface of the ink may not be tacky enough to pick up or release images from the pad
    • Solvents evaporate too quickly
    – Ink might not pick up from the cliché because it has dried in the etched portion of the plate, or dried on the pad in transit to it’s destination.

    Same for the pad
    • Solvents evaporate too slowly
    – Only some of the ink will release from the pad to the substrate
    • Solvents evaporate too quickly
    – Ink dries and stays on pad.

    Tips
    • Warm environments: Add solvents every 20 – 30 minutes. Always add a measured amount, use a viscospatula and don’t guess!
    • Control temperatures: Keep printer out of the sun, away from drafty entrances, exits, dryers.
    Keep the temperature of the substrate to room temperature.
    Don’t let printed part drop below 59°F until fully cured – 4 days or longer.
    • Good housekeeping: Dust and vacuum floors instead of sweeping. Avoid cardboard boxes in production area. Wipe down all surfaces using a damp cloth.
    Static electricity feathers the print. Slow the down stroke and pickup.
    • Too hot: Solvents in the ink will evaporate very quickly. Solvents are attracted to water vapor molecules in the air.
    – Speed up the forward travel of the pad stroke.
    – Thinner / retarder mix (75% Thinner to 25% Retarder)
    • Too cold: Solvents won’t evaporate quickly enough. Ink won’t be tacky enough between pickup and and lay down to transfer completely to the substrate.
    – Slow down the forward travel of the pad stroke
    – Select a faster drying thinner
    – Use a hair dryer pointed at the pad as it travels forward after ink pickup to speed up the evaporation of the solvent
    – Raise ambient temperature.

  7. All Fired Up: Pad Printing Glassware

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    All Fired Up: Pad Printing Glassware

    These cups were printed on the BottleJet 2.1 Cylindrical inkjet Printer.

    Most glassware has some kind of discernible shape. Logically, pad printing emerges as a natural choice in glass decorating and printing. The more complex the shape, the more suitable pad printing becomes as a decorating process.

    With the right tooling, multicolor prints, special-effects inks, and even 360 degree wrap-of-image-around-circumference are possible. Automated parts-handling options can further speed production rates.

    There are two primary inks used in pad printing glassware: frit inks and acrylic inks.

    Acrylic inks
    Acrylic inks are mixed with a catalyst hardener as well as with a solvent thinner, which allows the ‘tack-up’ and transfer from cliché to pad to part. A post-print bake is usually recommended (3-5 minutes at about 200 degrees F) to improve the durability of the print. The bi-component ink mixture typically has a ‘pot life’ of 6-8 hours, after which time the ink hardens on its own, rendering it unusable for any further printing.

    Acrylic inks are fairly durable, providing at least 50 wash cycles in your average home dishwasher.

    Frit inks
    For greater durability, a frit ink is the way to go.

    Frit inks contain:

    1. Finely ground glass particles in the ink mixture (very small, only a few microns in size)
    2. A pigment (the colorant)
    3. A binder, which is a carrier used to keep the ingredients in suspension
    4. A thinner, the solvent which facilitates the silicone pad transfer process.

    Different frit suppliers recommend different combinations of the above four components. There are no pot life issues to consider when using frit inks.

    After printing with the frit ink, the printed ware is fired in a kiln, typically at about 1100 degrees F on average for up to 30 minutes. The ground-glass particles come very close to their melt point; the organic ingredients in the print burn off, and a physical bond is created between the print and the product. Frit inks are generally considered the most durable of all glassware prints, capable of lasting a lifetime and providing tremendous abrasion resistance.

    Have you had glassware decorating challenges? Feel free to contact us for advice on the best options for all types of pad printing on glassware.

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