In the vast world of flexible packaging, it is critically important to control the adhesives used to bond laminates such as films and foils-which require meticulous accuracy when blending, dispensing and applying adhesives-to substrate materials. The adhesive controls required for such accuracy are often missing from nearly all systems, however, although the consequences can be dire and may include packaging failure, product loss, and significant downtime.
If not applied in the correct coat weight (whether too light or too heavy), the lamination bonding can fail and cause the overlay to bubble, blister or otherwise delaminate from the base material. This can become a nightmarish scenario that worsens as the problematic packaging travels farther down the distribution chain.
“The ultimate dilemma created by delaminated packaging is when it reaches the store shelf, which is a terrible situation for the product manufacturer and packaging supplier and could easily cost hundreds of thousands of dollars,” says Ray Mayes, a packaging controls specialist whose firm, Cereal City Electric, services the midwestern U.S. food industry. “If you were to seal a food product into packaging material that later began to delaminate, you would then be wasting the product as well as the packaging.”
Even when delaminated packaging never leaves the plant, it normally takes adhesives about three days to cure. At that point, a quality problem forces the packaging producer to go all the way back to reprinting the packaging and then laminating it once again.
“This is a just-in-time world,” Mayes explains. “When you have a lamination error, it is almost impossible to really make up for it. You have to squeeze back in the production queue, which is very difficult. The printer may be backed up. The printer or packaging house may be short of materials, and it can take considerable time to replenish them. In any event, it’s a very difficult and costly situation.”
Controls NeededMayes attributes most delamination and other coatings problems to a lack of control with the blending, metering and dispensing of adhesives. Because most adhesive blending and dispensing equipment uses only single gauges to meter adhesive coat weight, the process can slip out of control without the operator or system being aware of it.
“Unless the adhesive’s viscosity and flow rate are validated by a secondary metering system, you have no real control at all,” says Bruce Schuetz, who has worked in the metering and blending industry for over 30 years. The need for a comprehensive adhesive blending and dispensing feedback and control system led Schuetz to found InLine Blending Solutions and develop a line of solid and solvent-borne adhesive blending and dispensing equipment that focuses on true process control.
To provide the required level of control, the equipment is designed to enable accurate, validated metering, and dispensing to high-volume inline blending and mixing operations. As he developed products in collaboration with customers, Schuetz realized that additional benefits could be incorporated with the adhesive mixing and dispensing systems, including improved system availability, a more healthful working environment, reduced maintenance requirements, and enhanced plant appearance.
Case in PointInLine Blending Systems works closely with prospective customers by collaborating on system analysis and performing a no-commitment site survey to optimize applications and reduce risks. The outcome of this preliminary work can lead to important innovations and benefits that impact lamination operations in multiple ways.
For example, Schuetz worked directly with Mayes when he was a controls manager with Cello-Foil (now Exopack). Mayes wanted to improve the verification of coat weight on two-component polymer adhesives used in laminating 10-gauge films on packages. “Before we had the control system, it wasn’t uncommon that we could have a delamination claim from a customer that could be as high as $100,000,” says Mayes. “Once we got the new control system in place, we had complete reliability and never saw any claims.”
Mayes explains that the InLine Blending Solution’s equipment includes two independent metering technologies, and the company is also working on a solid-state polyurethane coat weight analyzer. Until recently, such “intelligent” microprocessor-based control of adhesive blending and dispensing had not been available. “With this unique system, it is a simple matter to verify mix ratio and coat weight,” says Mayes. “This is a very powerful capability. These advanced systems are constantly monitoring and validating flow rates.”
In the collaborative process of designing the equipment, Mayes saw opportunities to improve productivity while ensuring that lamination problems were eliminated. He adapted the adhesive unit design so that it became modular, which enabled operators to remove a unit containing one type of solid adhesive and simply roll up another unit containing whatever other adhesive was required for the particular job.
“We had each unit built on wheels, so that we could pull it right up to the machine and run one adhesive,” Mayes explains. “If the next order was using a different adhesive, we’d just roll the first unit out of the way and replace it with another machine that was already equipped with the needed adhesive. Using that method, we didn’t have to clean up and go through a lot of changeovers. The benefit, of course, was increased system availability as well as a reduction in the cleanup of the machines.”
Another significant maintenance and productivity benefit came from the incorporation of PTFE (Teflon®) coating on the components and seal-less pumping cylinders of the blending and dispensing equipment. Many manufacturers use cylindrical rod-type pumps that are exposed to the adhesive. Because the rods eventually get adhesive on them, that adhesive begins to adhere and is cured by the air. On models containing seals, the rods ultimately become so sticky that they literally tear the seals out of the cylinders, creating uncontrolled flow and a messy situation.
“The way the new system is designed, the cylinder and rod are encapsulated,” explains Mayes. “They are seal-less and airless so they never come in contact with the atmosphere. Any parts that might be coated with adhesive are not a problem because the adhesive is not exposed to the atmosphere, and it never gets the chance to cure. Therefore, we could put the equipment aside for two months and the adhesive would not have cured, whereas other equipment couldn’t be left for more than two days without having to be cleaned.”
The appearance of the equipment is another advantage; the PTFE coating of the InLine equipment both eliminates the extensive cleanup problems of other equipment and makes it look more professionally maintained to visitors to the plant. In addition, the occurrence of volatile organic compounds (VOCs) is a major environmental and employee safety concern in every plant. Because the solvents used in many adhesive systems are both a U.S. Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA) concern, minimizing the yield of VOCs is another goal of the InLine Blending Systems design.
“With this system, the operator never touches the product,” says Mayes. “We apply it out of a drum that is sealed with a valve on it. You simply bring up the drum on a cart, quick-connect the hose, and turn the valve on. Everything else is automatic. That minimizes the VOCs that can escape from the adhesive and into the plant air.”
For more information, contact Inline Blending Solutions Inc. at 23535 Park Rd. N, Forest Lake, IL 60047; phone (847) 875-2066; fax (847) 438-2664; e-mail email@example.com; or visit www.inlineblendingsolutions.com.