Product Reviews

Release Liners

April 26, 2007

These vital components of the pressure sensitive laminate are steadily evolving in a marketplace that is changing through competition.

Release Liners

These vital components of the pressure sensitive laminate are steadily evolving in a marketplace that is changing through competition.

By Jack Kenny

Without a good release liner, a pressure sensitive label cannot be diecut or dispensed. It’s that simple. Though diecutting and dispensing are separate operations performed at different locations by different companies, they both are fully dependent upon the integrity of the release liner. If the liner cannot resist the force of the cutting die, and if it cannot withstand the speed and rigor of application, it’s a liability.

The world’s major release liner manufacturers know well the need for product integrity, and have solid reputations behind them for quality. Their products go far beyond use in labels, and include such industries as medical, large graphics, hygiene, and tapes.

It is, however, a market in a state of change: Price pressures have their effects, capacity in North America is said to be somewhat high, and a couple of companies have been on acquisition sprees in the recent past, changing the landscape for this segment of the packaging market.

At the 2007 Global Release Liner Industry Conference, held in March in Chicago, Corey Reardon announced that release liner market growth for North America and Europe was just above 4 percent last year. Asia, however, grew at 9.8 percent, and South America at 12 percent. “Because of these high growth rates, capacity utilization in silicone coating is moving upwards — to a current estimate of 65 percent for in-house coaters and 74 percent for commercial coaters,” said Reardon, who is president of Alexander Watson Associates, sponsor of the conference. He added that Loparex and Mondi Packaging, the world leaders today, “now constitute the combination of at least nine previous release liner manufacturers.” Among the most recent were Loparex’s purchase of Douglas-Hanson and Mondi’s acquisition of Akrosil and S+E.

Liner properties

“The function of a top quality release liner is to improve the quality and efficiency of substrates so that they diecut, run at high speeds and apply effectively and efficiently, at the lowest total cost,” says Daniel Brown, director of marketing and strategic planning for label, release and specialty papers at Boise Paper, Bensenville, IL, USA. “There are many ways that the quality of our products can have an impact on runability. In prime label applications, pressure sensitive substrates ultimately are more costly materials than others, such as glue applied. The reason they continue to take market share is that you are ultimately able to use a process that is more efficient. Ever faster equipment applies the labels onto consumer goods at high speeds. The substrates have to work effectively at high speeds, and they have to apply quickly and accurately at high speeds.”

Most release liners in use today are made using paper stocks. Only about one fifth of liners worldwide are film based, but that number is reported by everyone to be growing quite well.

Photo courtesy of Loparex
“In North America, by volume, the most commonly used liners are made of super calendered kraft (SCK) stock, in calipers of 2.5 mil and 3.2 mil,” says Todd Schweigert, director of marketing for Loparex, Willowbrook, IL. “Label converters traditionally use 2.5 caliper. In Europe the market prefers glassine liners (glassine is a more densified paper), in calipers of 2.0, 2.2 and some 3.0.”

“Most liners used in the market are bleached papers. But the label converters are trying to take costs out today because of the inability to pass along price increases, so now the thinking is more toward the natural paper grades, instead of bleached. Bleaching is the accepted paper — it has always been used, but there is really no need for it. The smaller converters would like to make that change, but they don’t dictate the market. As soon as the larger players begin going to natural grades, that will start to happen.

“Between bleached and natural papers, there is not a great deal of price difference, but any little bit helps.”

Film bases

According to Peter Vert, adhesives application engineer for Dow Corning, Midland, MI, USA, the use of films for silicone release liners has inherent advantages, such as diecutting performance, the potential to reduce silicone coat weight, and high speed conversion without web breaks.

“These advantages make film release liners ideal for application trends such as clear-on-clear labels for the beverage and personal care markets,” Vert says. “Films are the fastest growing segment of the release liner market.”

Liners made from films make up about 15 to 20 percent of the release liners used in the label industry, says Schweigert, but are growing at a faster rate than papers. “These film liners are predominantly polyester. There are others, but they make up a smaller percentage. Polyethylene, for example, is seldom used liner in the label market. You’ll find it as a liner in the industrial and tape markets, but not in the graphic arts and label markets.”

Film liners tend to be for higher end label applications. “They provide a smooth deposition of adhesive so when the face stock is laminated to the liner, it shows no appearance of the label,” he adds.

Price pressures are bringing requests for ever thinner film liners, say the producers.

“Newer film based release liners are going down in gauge,” says Ben Reif, vice president and general manager of Wausau Coated Products, Wausau, WI, USA. “Whereas two or three years ago you heard about 1.5 mil polyester, now people are using 1.2 mil polyester. We even have customers asking for 1 mil or 0.98 gauge. which we can do and have done. I don’t know where this ends, the effort to drive cost out. Using less film and paper is one way to do it.”

There are tradeoffs, however, notes Reif. “Reducing the gauge affects our efficiencies on our coater; it can result in necking or stretching, and web breaks when they are being applied. A 1.2 mil liner works well, but when you go thinner than that, tension becomes an issue. You might be diecutting down into it. A 1.5 mil liner can take some cutting into it, but with a lower gauge you have to be careful with tension and speed. If speeds aren’t as high, you might be able to get away with a thinner liner.”

Rayven, of St. Paul, MN, USA, manufactures release liners of several types, specializing in films: 2 mil polypropylenes, HDPE and LDPE. “Years ago all of our raw materials were purchased here in the US,” says Rick Mercado, director of sales and marketing. Over the last three years we have been buying film from overseas. China now has producers of film with excellent quality, but you have to plan accordingly because shipments take eight to 10 weeks. We have good procurement and good sources. The giants of the industry don’t have an advantage with polypropylene.” Mercado says that about 20 percent of the company’s sales are for use in the label industry.

New products

Several release liner suppliers have developed paper products that are not SCK or glassine, and have either launched them in the recent past or are planning to do so soon. Among these is Stora Enso, of Stevens Point, WI, which released its LumiSil last year at Labelexpo in Chicago, and this month in Latin America.

“It’s not an SCK, it’s a coated paper,” says Joe Briganti, business innovation manager for technical papers at Stora Enso. “There is some clay in there; it has a thicker coating on one side of the sheet, and gets a very good holdout.”

In the past, Briganti explains, coated liners were known to soak up silicone, which inhibited the curing of the liner. When a liner does not soak up the silicone, it is said to have good holdout. “Our holdout is as good or better than any SCK and glassine because of the components we use,” he says. “However, the marketplace says that clay coated or coated liner will never hold out. We have overcome those issues, but people still have paradigms that they cling to and don’t want to change.

“LumiSil is moving well in North America, and has been approved at one very large company, one small, one medium, and we are in trials at two other large companies. It’s a long process. The paradigm is that it won’t work, so we have to prove it repeatedly. The good part is that once you are approved, you stay approved.”

Photo courtesy of Rayven
“Converters today have the perception that SCK and glassine are required to produce the best translucency for light sensing, and the best qualities in a release paper,” says Daniel Brown. “What Boise is doing is changing that paradigm. We have achieved the required qualities in a technology that is really not SCK and really not glassine, nor is it clay coated kraft.

“Our technology is called Adaptive Coating and Calendering (ACC). It combines characteristics from SCK, glassine and clay coated kraft. Our proprietary technology essentially expands the number of variables that we can use to achieve the required properties.  This allows us to ‘adapt’ our process, increasing or decreasing the amount of coating or calendering, to achieve the optimal characteristics for our customer’s application.

“The industry has been stuck with certain products. Until now it has been: ‘If you want this particular application, we give you this product.’ Boise now has the ability to use one core technology across the full range of release liner applications. Simply stated, we have increased the industry’s set of options.”

Boise calls its new product line AvantEdge. It was launched in late April.

Loparex manufactures a product aimed specifically at the label market, which is called Converter’s Choice. “It’s a natural kraft paper with polypropylene extruded on one side,” says Schweigert. “It fills a gap in the market between film and paper liners, and it makes up another 15-20 percent of the market for us.”

The release capabilities of the liner might be specified by the end user, and the label converter quite often knows what type of liner to use for what application. Still, opinions vary as to how much a converter should know about release liners.

“A label converter’s customer traditionally needs to know very little about release liners other than they work,” says Schweigert. “The converter’s customer is buying a sandwich; they are more concerned about the facestock and how it prints. They want to know how the web will handle, and know that it will release well when the time comes for application.

 “The converters that we sell our products to have to know a fair bit about liners. They formulate the adhesives, we formulate the silicones, and those two together have to achieve the desired result. Our customers want to know that our release remains consistent.”

“Converters know what type of liner they have always needed,” says Mercado. “Nothing has been engineered new. There is no brand new product unless you are talking about companies requiring a clear label. In that regard you have some requests from people who want a low dust level, or no dust. It depends on where you coat it.”

Reif, of Wausau Coated Products, has a different view: “Converters should worry about the liners. A lot is happening with facestocks. There are alternatives from the Pacific rim coming to these shores, and they are a lot less expensive but difficult to diecut. When you have tough films you had better know what kind of release liner you are using.”

Opinions of release liner users were expressed at AWA’s Global Release Liner Conference. “As users, we have very little knowledge of the differences in the silicone systems,” said Mitch Allen, general manager of Arlon Viscor, a tape and foam manufacturer in Dallas, TX, USA. “Our suppliers need to advise us and make it easier for us to find the information we need.” In pursuit of the perfect supplier, he listed his specific requirements: “We need improved product data, better technical communication, easier access to product testing, and faster turnaround and lead times.”

The market

“Growth has plateaued as the industry has matured over the last five years, but we still see it as attractive at around 5 percent,” says Brown. “It was 6.5 percent to 7 percent a couple of years ago. I believe we will continue to see GDP plus 1 to 3 percent over the next five years.” In contrast, he adds, Boise Paper has experienced growth at a greater than 17 percent CAGR over the last five years.

Pressures on any market related to paper and films are tremendous these days, and the release liner companies have additional headaches. Platinum has traditionally been a catalyst in the silicone release product, and the price of platinum is stellar.

“Like all others, we have experienced unprecedented cost increases,” says Brown. “In the [large format] graphics segment we have been the market and technology leader with CCK liners. We have never in that 30 year history experienced the challenge we have faced in the last couple of years. For a paper manufacturer, this is a specialty segment. The sensitivity to raw materials cost inflation has become much more evident in the specialty segments. This inflation magnifies the impact of inefficiencies in the manufacturing process.  While there has been a continual evolution advancing specialty production to larger and more efficient assets, this period of raw materials inflation is accelerating this trend.”

Brown adds that Boise’s answer is the production of AvantEdge on its No. 3 machine in Wallula, WA, USA, the continent’s largest release liner substrate production plant for the pressure sensitive market. “While this will drive change, we believe the industry will benefit from higher quality products and reduced sensitivity to cost inflation on products we supply this industry of this machine in the future.”

Loparex, says Schweigert, segregates its release liner markets in seven ways: label, graphic arts, medical, hygiene, composites, tapes, and industrial. “Because of the downturn in the housing and automotive segments, the industrial market is flat right now, but not in a decline. The hygiene market is also fairly saturated and flat.

“Everything else is growing at a rate of 3 to 5 percent. The medical category is growing a little faster, but as a whole it’s a smaller segment.

“Platinum and solvent costs continue to climb,” he adds. “Paper and films are on an upward trek as well. When we have to put a price increase through, we don’t take it lightly. We have eaten a lot of raw material increases over the past year.”

Believe it or not: Release liner is recyclable

Silicone coated release liner is recyclable. That doesn’t mean it is being recycled in any significant amounts. The subject of liner recycling has been examined by the Tag & Label Manufacturers Institute’s Environmental Committee, and is all in favor of it. But according to Calvin Frost, the committee chairman, nobody’s listening.

“Paper and film release liners can be recycled and taken back to its original form, which is fiber or resin,” says Frost, chairman of Chicago based Channeled Resources Group. “The silicone can be mechanically skimmed off from paper or remelted from film quite easily. That process doesn’t use chemicals. What you have left is raw material for reuse. It has good physical and mechanical properties.

“There are many different grades of waste paper, and spent paper liner is a grade that has value. When you get rid of that coating you have some great fiber, so the paper industry says ‘Bring it on’. That’s the primary application for silicone release liner.

“There is always the possibility of reuse. By reuse I mean actually making a laminate out of it. It’s narrow in most cases, 10" or less. But in the Asia Pacific arena we have found companies that have narrow web coating, and are able to use the spent liner to create new pressure sensitive product capability.”

The prevalent attitude toward release liner recycling among converters in the United States, Frost says, does not address environmental concern, but rather business practice and profit.  “They say: ‘If it’s not going to cost me any more money and I can get revenue for it, and I don’t have to do anything special, I’ll develop a collection program. But if it doesn’t fit within that paradigm, forget it’.”

Who generates spent liner? Whose responsibility is it to recycle it?

“The converter is not the one generating the liner,” Frost says. “It’s his customer. If he’s selling to a major brand owner with global sales, that end user is generating a lot of release liner.”

Are the big packagers of the world recycling spent release liner? “There are success stories,” he says, “but they are isolated. In general the answer is no.”

The time might come when the customer asks the converter to take on the responsibility of dealing with the spent liner. When that happens, competition will change, says Frost. But does it have to wait for that possibility?

“Only one company that I know of is proactive with liner recycling, and that’s Skanem (based in Norway). The company makes liner recycling part of its selling package: ‘If you buy our labels, you will get service, quality, price, and something else: an environmental solution to getting rid of spent liner. They have arrangements with other companies to facilitate the collection and delivery, a third party with expertise to solve the problem.”

The European paper industry, Frost says, is engaged in recycling, but is not willing to consume spent liners. “In Europe the liners are being recycled offshore. That’s a dilemma we have in that region. We don’t have any paper companies in Europe that want this stuff. It’s going to Asia-Pacific, where the economics all work because of low freight costs and the lack of raw materials. The demand for fiber is strong.”

North America, he adds, has half a dozen recycling plants, strategically located, that will accept release liner. What we don’t have in North America is enough volume.

“In the West — Europe and North America — we make two million tons of base stock for silicone coating. And it’s all recyclable. We recycle fewer than 20,000 tons. Where’s the rest of it?”

In the landfill?

“Thank you.”