Technical Bulletins

Do I need to mix UV coating?

— ICP Industrial recommends mixing all coatings (UV and Aqueous) prior to use to insure that the coating is uniform prior to application

Can I coat with either a Dull or Satin UV coating and then spot coat Gloss UV on top?

–To accomplish this you must make sure that the first applied UV coating is coatable.ICP Industrial provides special coatings for this type of job that do not contain additives that can affect the adhesion of the top UV coating.

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…ICP Industrial’s Developmental chemists formulate with “green” in mind. The raw materials and vendors are carefully selected to ensure consistent quality of our finished products. Our manufacturing processes do not utilize any heavy metals, nor do our products contain any heavy metals listed under CONEG – RoHS or EU Directives EN71(3).

…Finished goods coated with ICP Industrial Aqueous and UV coatings can be introduced into recycling facilities and be further processed to aid in post consumer recycled paper, paper board, and plastics

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…A chamber bladed system is an enclosed system flowing from drum to pump to chamber and back to the original drum.Theoretically the system does not allow foam to develop, however in practice, this is not the case.Air finds a way into the coating by means of:

• Excess hose lengths
• Worn hoses
• Leaking diaphragm pumps
• Worn doctor blades
• Large cell volume
• Excessive circulation speeds

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…Upon inspection, the ideal result is to have complete release from coating to coating and coating to back-side with no visible markings on either side of the samples. This test is performed internally for all ICP Industrial products prior to any field trials or live production runs. If a customer experiences blocking issues, all materials used by the customer should be tested for block under controlled laboratory conditions.

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Contrast varnishes are specially formulated to impede the coating’s ability to lay with a smooth, glossy appearance.The varnish is applied in the final ink station of the sheet-fed printing press, and then coated in-line with the appropriate coating to create a “contrasting” appearance in the varnished areas as compared to the unvarnished areas.The major advantage of using contrast varnish is that the work is done in-line, resulting in quicker throughput and elimination of registration issues.

This technical bulletin will discuss the best practices to follow when working with contrast varnish and Aqueous or UV coatings…

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..If the load temperature for side one is 90 ± 5°F, we recommend side two load temperature to be maintained between 85°F and 90°F. If side one is not thoroughly dried, it will be susceptible to re-wetting by side two. (The longer the time between coating the second side, the higher the load temperature can be.)…

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This Tech Note refers to two-sided sheet-fed jobs. Work-and-turn , work-and-flop, sheet-wise. Using water-based coatings, aqueous.

Timing Variables

There are many variables that determine the timing or when a job can be backed up. The most important factor is the formula of the coating. The water-based coating should be formulated for two-sided work. The coating should dry fast, dry hard and be able to pass a face-to-face, coating-to-coating, block test. ICP Industrial’s block test is 2psi @ 140°F for 24 hours.

Drying Systems

Another important factor is the drying system on a press. Current drying systems include hot air, infrared and exhaust. Hot air, air movement, velocity and evacuation are key in the process of drying aqueous coatings. The infrared can help both the coating and the ink. Water-based coatings dry through absorption into the stock and evaporation of the water, ammonia and co-solvents.

If the drying system can assist in drying the coating faster, the job can be backed up sooner.

Substrate Type

The type of substrate and ink coverage also make a difference in when a job can be backed up. A premium 100 pound cover stock may need more time than a 14 pt. SBS C2S. A heavy four process job will need more time than light screen work. The type of ink used can play a significant role. Generally, a faster setting ink will improve turnaround.

Load Size

The size of the load needs to be considered as well as airing the loads. The smaller the load, and the more air introduced into the load, the faster a job can be backed up.

Coating Amount

Another factor affecting the timing of the two-sided work is the amount of coating applied. A general rule of thumb is the thinner the film or coating weight, the better. We recommend .5 to .75 wet pounds of coating per 1,000 square feet.

Pressroom Conditions

The less humid and cooler the pressroom (room temperature at 72°F), the faster a job can be worked-and-turned.

Rule-Of-Thumb

Although all of our customers operate under many different conditions, have various types of printing presses, coaters, drying systems and run different formulations, commercial printers successfully backup jobs within hours using our coatings. Most commercial printers, through their own experience, determine what works best for them.

All of the conditions discussed come into play when backing up a job. The learning curve comes quickly when factors such as coatings, ink, drying system, stock, coating weight and press conditions are taken into account on each specific job.

Re-Softening

When running 2-sided aqueous coating work in sheet-fed pressrooms, various sources of technical information (press, drier, ink and coating manufacturers) recommend different load temperatures.

They use the term “re-softening” when warning press operators not to run too high of a load temperature. It should always be considered that the coating formulation is still the most critical part of successfully running two-sided work.

Drying Variables

There are three variables that impact the drying of aqueous or water-based coatings: Hot air movement, air evacuation and infrared. Although load temperature is important, we believe it is only one part of the drying equation.

There are many configurations of drying systems, some with and some without extended deliveries. Hot air movement is still the most important criteria to dry water-based coatings. Yet the infrared which helps dry the ink and coating should not be forgotten.

Load Temperature

Load temperature is directly related to the amount or effectiveness of the infrared system and the thickness of the stock. If the sheet can be delivered dry at a minimal load temperature, that would be an ideal situation. However, if the sheet is not dry with the current drying system, we feel the first side load temperature should be 90°F +/- 5°.

The sheet, when delivered should be dry to the touch. If side one is dried sufficiently and it is a two-sided coating, it should pass a block test of 140°F/2psi/24hrs (coating to coating), provided the ink is dry.

If the load temperature for side one is 90° +/- 5°F, we recommend side two load temperature be maintained between 85°F and 90°F. If side one is not thoroughly dried, it will be susceptible to re-wetting by side two. The longer the time between coating the second side, the higher the load temperature can be.

Sticking or Picking

A backup 12 hours later might allow the second side load temperature to be the same as the first side. Coating side one, but not adequately drying side two, could allow side two to re-wet side one. This is not a resoftening of the first side coating, but sticking or picking side two to side one.

Watch Out For Re-Wetting

Most importantly, the second side needs to be dried as well as the first side. Why? To dry the aqueous coating and prevent re-wetting. Remember, if the coating is dry to touch in delivery at a lower load temperature than the first side, with the current drying system, then that should be the load temperature run.

This is the first in a series of Tech Notes about volatile emissions and what printers can do to comply with regulations while maintaining high quality operations.

VOC Definition

VOCs are volatile organic compounds – organic (carbon-based) compounds that are volatile (evaporates easily).

VOCs Importance

VOCs lead to the formation of ozone and smog. Because of the health and environmental hazards, most printers are required by law to track and control VOC emissions.

VOCs in Printing Operations

VOCs are found in inks, fountain solutions, press washes, press varnishes, solvents and aqueous coatings.

Aqueous Coating VOC Content

Typically, aqueous coatings contain less than 5% solvent. Some are as low as 1-2% solvent.

Emission Reduction

Examine print processes for ways to reduce solvent use without sacrificing quality. Implement simple solutions with broad application.

Switching to aqueous coating is simple, and aqueous coatings can be used for most jobs to reduce VOCs.

Reduce VOCs & Maintain Quality

It’s a balancing act. The law sets standards for annual VOC emissions. By looking at the entire process for each job, you will find ways to save on VOCs in one area so that you can “spend” them in another.

Some low-VOC products, such as aqueous coatings, perform better than their traditional counterparts, such as press varnish. You may find that by switching to aqueous coatings, quality actually improves while VOC use goes down.

Reduction Tips

• Use products that meet performance criteria and have the lowest VOC content;
• Manage solvent use throughout the year. By using low-VOC products regularly, you can accommodate the jobs that require high-VOC products;
• Re-evaluate coatings. Making the simple switch to aqueous coatings significantly reduces annual VOC emissions;
• Use custom aqueous coating formulations. Ask your ICP Industrial professional for a custom coating that will meet all of your performance goals;
• Use lower VOC links, then add aqueous coating for gloss, satin and/or functionally protective coatings;
• Use alcohol-free fountain solutions.

Best Step to Reduce Emissions

Make aqueous coatings your standard coating. Aqueous coatings contain significantly less solvent that standard press varnishes. And, they don’t require solvent-based cleaning solutions. Because aqueous coatings perform better than varnishes, you will see better results and reduce VOCs.

ICP Industrial Helping Printers Comply

ICP Industrial is continually formulating coatings with minimal VOCs. We encourage our suppliers and our own research and development team to push the boundaries to create coatings with the best performance at the lowest possible VOC content.

This is the third in a series of Tech Notes about volatile emissions and what printers can do to comply with regulations while maintaining high quality operations.

How VOC Emissions Are Figured

Annual VOC emissions are calculated based on how much solvent is contained in the products you use, multiplied by how much you use.

How Much Solvent Products Contain

The manufacturer can tell you, in one of two ways:

• Pounds of solvent per gallon of product; or
• Percentage of solvent in product.

The amount of solvent in pounds per gallon is the VOC number. This is the number the EPA says you must use to calculate annual VOC emissions.

VOC Number Accuracy

Unfortunately, VOC numbers aren’t always accurate. The EPA’s method for figuring VOC numbers is not accurate for products that contain very little solvent-like aqueous coatings.

The EPA method (called Method 24A) starts by removing all of the water from the product (fountain solutions, aqueous coating, etc.) through a process called titration. Then, a mathematical calculation is used to figure out how much of the remaining material is solvent. Basically, the calculation says, “If we take out all the water and subtract the solids, the remainder is solvent.”

EPA Method Doesn’t Work For Aqueous Coatings

The EPA method assumes that titration removes all of the water from the product being tested. That doesn’t happen in the real world; there can be a significant margin of error. The EPA method doesn’t take such errors into account: Any water that remains in the product after titration is counted as solvent.

For example, let’s say we’re testing an aqueous coating that contains 4 percent solvent. The titration procedure removes only 97 percent of the water. Remember, whatever water the titration fails to remove, in this case 3 percent, is counted as solvent in the test results.

Though the titration error is small, the impact is significant. The test results will show that the coating contains 7 percent solvent — that is, the 4 percent solvent that is actually there, plus the 3 percent water that the titration missed. Because aqueous coatings contain so little solvent, a small margin of error in titration has an important effect on the final test numbers. That is why the EPA test method is not appropriate for aqueous coatings.

A More Accurate Measure

ICP Industrial lists the solvent percentage on the MSDS sheet. The solvent percent is a more accurate way to measure the amount of solvent in an aqueous coating.

A Better Way

It’s called chromatography. This is a laboratory procedure that separates the solvents out of an aqueous coating, then weighs them. The procedure itself is straightforward, but it requires sophisticated equipment. For aqueous coatings, chromatography is generally considered more accurate than EPA’s method. That’s why ICP Industrial uses both Method 24A and chromatography to determine the solvent content of its coatings, which is listed on the MSDS.

However, you should know that, although chromatography is more reliable than Method 24A, and it is routinely used by chemical manufacturers, it has not yet been approved by the EPA. This means the EPA may consider you noncompliant if you rely on VOC numbers determined by chromatography rather than Method 24A.

ICP Industrial can provide you with both VOC numbers and percent solvent as determined through chromatography.

Figure The Solvent Percent

Remember that aqueous coatings are mostly water. To figure the solvent percent of an aqueous coating, you first have to subtract the water. After you have eliminated the water, you can calculate the actual VOC.

The calculation for products that are mostly solvent, like press varnish, uses a simpler version of the same equation: