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I'm Rubber PUR is Glue

Feb 1, 2007 12:00 AM

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PUR binding is moving beyond manuals, coffee-table books, top-class publications and annual reports. In addition to high-end and midrange equipment, PUR now is offered on some on-demand perfect binders. The decision to add PUR capabilities boils down to two questions:

  • What are you printing?
  • Can you justify the cost to your customers?
If you are printing a newsstand publication with a life expectancy of only a few hours, a traditional adhesive will do just fine. If you are printing a massive magazine, such as a special bridal or fashion issue, PUR might be just the ticket.

College textbooks and computer manuals, which will be subjected to constant use and must lay flat, also are excellent PUR candidates. Ditto for certain on-demand books, especially if they include a glossy cover or any UV-coated pages.

While it won’t soon displace old standbys such as ethylene vinyl acetate (EVA) hot melt and polyvinyl acetate (PVA) cold emulsion adhesives, polyurethane reactive (PUR) is gaining ground—even for short-run jobs.

PUR’s benefits are well documented: It is strong (but sufficiently flexible to lay flat), largely impervious to temperature extremes, bondable to “difficult” surfaces such as coatings or plastics, and virtually immune to ink migration headaches.

At about $4.50 per lb., PUR is more expensive than EVA adhesives, which generally cost $1.30 per. lb. (See “PUR in every glue pot?” April 2005.) But some users say the expense is more than justified by a binding they can virtually guarantee won’t fail. And, for certain challenging jobs, PUR might be the only viable option.

Many trade binders and commercial printers already have made the leap. AMERICAN PRINTER spoke with two of the technology’s earliest adopters, as well as some vendors, about key PUR trends.

Early adopter
Did you ever have a DOS-based computer? You probably don’t miss the long strings of code or the software instruction manuals that were delivered in bulky three-ring binders. But those manuals, the mainstay of the 1980s computer revolution, represented a golden PUR opportunity for Whitehall Printing, which was then based in Chicago. Bindery guru Hans-Dieter Ehlermann, then with Wohlenberg, advised the printer to investigate the new glue.

“We were doing a lot of software documentation back then,” recalls Whitehall president Jeff Hirsch. “[Customers] needed these 300-page [books], and the typical user would have this manual out on their lap. You wanted it to stay open, and, in a typical office, those manuals would get used heavily. I was tempted to use a cold glue for a flexible product, but when we did page-pull tests, they weren’t very good.” Hirsch happened to meet with Wohlenberg’s Ehlermann, who was very excited about PUR and a few of its fledgling users. He convinced Hirsch to test an early system, which he added in 1991. “Hans-Dieter said, ‘You really have to try this stuff, it’s going to be great!’” Hirsch says. “So we did, and it was.”

Better binding
Hirsch’s father, Mike, founded the 90-employee, 75,000-sq.-ft. company in 1959. Whitehall Printing moved to Naples, FL, in 1991. The new facility was being built from the ground up, and Hirsch had seized this rare opportunity to design the plant around new and future book manufacturing systems, the company’s specialization.

Whitehall operates two Wohlenberg standard roller-style perfect binding lines, distributed by Colter & Peterson (Paterson, NJ). The lines are configured with various options, such as two glue pots for traditional hot melts using two different adhesives or a primer. The company has an additional pot for PUR, and all three pots roll out so another unit can be rolled in. According to Hirsch, the PUR pot must have a slippery coating, such as Teflon, so the glue doesn’t stick to it. The systems also are wired and prepared for high-frequency driers for use with PVA cold glues, which Hirsch says was done in case of problems with the PUR. But, he says they’ve never had to switch.

The conveyor systems were designed so Whitehall’s operators could control the amount of time from adhesive application to trimming to range anywhere from 30 seconds to six minutes. Explains Hirsch: “We weren’t sure of the properties of the adhesives.”

Hirsch says he prefers a wheel-system applicator: “We felt that the wheel was a little more forgiving. If you’re using an extruder, it has to be a very precise relationship to every book block. And when you have a binder with a lot of clamps, you need all those clamps to be identical. Theoretically, they are, but after you run a machine a couple of months, you have little bit of bearing wear and they can be off a couple of thousandths of an inch from one to another. Then, you’re no longer in a laboratory condition. Having the wheel applicator, particularly having two wheels, is redundant and theoretically unnecessary, but it’s a little more comfortable.”

Rising to the challenge
Hirsch concedes there is a bit of a learning curve when tackling PUR projects: “It’s not something simple that you would just say, ‘If I buy these tools and turn it on, it will run well.’” One of the problems is that you don’t see instant results, and you have to compensate for a 72-hour cure time.

There also is a slightly slower run time. For shorter runs, Whitehall runs the machines at 3,500 cph, or 5,000 to 6,000 cph for longer runs. “In the case of shorter runs,” Hirsch says, “it doesn’t really matter how fast you run it. If you’re going up the street to 7-11, does it really matter how fast you drive? Whereas if you’re going 500 miles, having an average hourly speed will help you get there sooner.”

There tends to be more setup required with PUR than with traditional hot melts, Hirsch says. Also, it’s a more difficult process to monitor, because you can’t open a book right off the line; the glue is in a liquid state.

Hirsch notes that PUR glues have improved dramatically over the years. “Their green strength—when they’re coming out of the trimmer, the viscosity—is a little thicker, a little stickier, and the cleanup is a little bit easier.” H.B. Fuller supplies Whitehall’s PUR adhesive.

“PUR has substantially stronger adhesive and cohesive properties and yet is more flexible than traditional hot melts,” says Hirsch. “Also, PUR bindings perform exceedingly well in extreme heat or cold.” And for Hirsch, the investment has been worth every penny: “We have not run across a material that we could not bind with PUR.”

Ask and ye shall receive
“Our claim to fame is, ‘From basic to the extreme, if we can bind it, we’ll do it,’” says Bill Seidl, president of Seidl’s Bindery in Houston. The 75,000-sq.-ft., 33-year-old trade bindery takes pride in handling special projects and doing “everything our customers ask of us.”

Seidl’s Bindery has another claim to fame. Not only is the company a pioneer in PUR binding (Seidl’s added these capabilities 10 years ago), but today, 100 percent of its perfect binding work is done with PUR adhesives. Seidl says the decision was a no-brainer: “ We knew we were going [100 percent] PUR right off the bat.”

All in
Even books printed on 27-lb. stock don’t pose a PUR problem for the Texas bindery. “There’s quite a bit of misunderstanding about PUR technology,” Seidl says, “but our figures show that it’s less expensive than other types of hot melts, because you’re using less [adhesive]. And because we run it every day, our waste factors are low.” His operators not only are accustomed to the differences in application, but also have fewer changeovers to worry about, which means less wasted product at the end of the day. “A lot of people that start, stop, start, stop experience lengthy changeovers and lower productivity. By committing to the product and running it regularly, we’ve avoided many of the issues other companies have with it.”

Among a myriad of postpress equipment, including perfect binders, die-cutters, embossers, gluers and pick-and-place equipment, Seidl’s operates a Bolero perfect binder from Muller Martini (Hauppauge, NY) for PUR jobs. The Bolero utilizes an open dual-wheel pot applicator, which enables hyrdaflow action. A smaller pot contributes to minimal waste. The Teflon coating allows the glue to peel out for easy maintenance.

The Bolero can process maximum product thickness of 31?8 inches at speeds of 8,000 cph. It’s fully automated for quick job recall and consistency between jobs. Product parameters and production data are entered via touchscreen or a control unit networked to the job preparation department. Data also can be transferred automatically from the measuring station. The Bolero has an interface to the production line control system for the transfer of data in JDF format. Henkel is Seidl’s PUR supplier.

Now and then
Over the years, Seidl has seen PUR technology evolve, especially the glue. When the bindery made the move to 100-percent PUR capabilities a decade ago, it was among only a handful of dedicated PUR binders in the United States. At that time, glue manufacturers targeted their products for users that ran PUR jobs as infrequently as every other week. “Initially, PUR adhesives were designed for companies that were using only one drum every month or two. We were using 12 or 13 drums a month, so we were looking for an adhesive with higher pot stability, which would result in less cleaning and less downtime,” recalls Seidl.

Seidl’s can now procure glues with greater pot stability—the company can run for 36 hours before cleaning the pot. Glues also can have activators added to speed cure time, but the machines can be run for only 12 hours.

“We prefer running longer,” says Seidl. “We’re confident our adhesives will cure just fine and create a very strong binding. The longer PUR has to react with the paper fiber, to soak in and get a bond, the better. We go for longevity.”

The biggest challenge for Seidl is customer education. Customers who handle a book fresh off the binder may panic because the glue hasn’t cured properly. But, after seeing a finished product and testing the page pull strength, they’re thrilled with the result.

To those who still doubt the benefits of PUR—or are hung up on the cost—Bill Seidl suggests looking at the big picture: “It’s cheap insurance. Fifty cents worth of glue buys you peace of mind for a $10,000 print job. How valuable is that $0.50 of glue if the binding fails?”

New nozzle and perfect binder
Muller Martini’s (Hauppauge, NY) Corona, Bolero and Accoro and Pantera perfect binders are PUR-compatible. (Although the company no longer manufacturers the Normbinder, Monostar, Starplus or Trendbinder models, PUR retrofits are available.) A new VPN book spine nozzle reportedly facilitates PUR binding on high-speed jobs on the Bolero, Corona and Acoro (A5 and A7). Glue film can be applied precisely with constant, minimal thickness and with exact glue break edges. This results in books with sharp-edged, chiseled spines and a higher quality appearance.

Because the VPN nozzle is a closed system, the glue isn’t exposed to moisture and humidity (which can cause some of the glue to react before being applied to the book spine). Quality remains consistent while cleaning and maintenance costs are reduced, because the glue pot doesn’t need to be recoated.

Midrange binder debuts
At Graph Expo, Muller Martini debuted the Pantera, a 4,000-cph binder that replaces the Tigra model. Offered with both hot melt and PUR, midrange Pantera can be configured with up to 28 feeder stations. It comes with a drum cover feeder and can be equipped with an optional crash feeder station for hardcover book production.

The Pantera is easy to operate, via a touchscreen monitor. An interactive setup assistant companion supports the operator, even with manual adjustments. The settings for all stations are displayed for the current production. The setup assistant companion monitors glue pot and spinner temperature as well as glue level. Automatic glue length control for spine and side gluing is also provided. Makeready times can be further streamlined when the binder is equipped with the AMRYS (Automatic MakeReady System).


Short-run solution
With print runs getting shorter, perfect binders must handle fewer books, efficiently and economically. Heidelberg (Kennesaw, GA) lends a hand with its Eurobind 4000, which can be equipped with PUR.

Steve Calov, postpress product manager, stitching and perfect binding, Heidelberg, says the target market for the Eurobind 4000 is a commercial printer currently outsourcing books it would prefer to keep in-house, as well as trade binderies that want a machine for work in the 5,000 to 10,000 range.

“Some stuff that used to be saddlestitched is getting perfect bound,” Calov notes. “People like the idea that they can print on the spine of the book, and because people are getting so competitive with their perfect binding equipment, they’re taking saddlestitch projects away.”

The Eurobind 4000 comes with a choice of two different three-knife trimmers. Two spine preparation stations are extendable with one or two optional stations. The machine has an average speed of 4,000 cph. “A lot of people don’t need the speed,” Calov notes, “They need the consistency, the quality.”

The machine has a removable glue tank on wheels that allows the user to change from traditional hot melt to PUR and back again. “In PUR, there are different ways to apply the glue to the spine,” explains Calov.

“One is a roller tank and the other is a nozzle. It seems more and more people are going toward the nozzle because it lays the glue uniformly across the spine vs. a roller tank, where you could have inconsistent film on the backbone. We decided, ‘If we’re going to build something, let’s go to the next technology and do nozzle.’”

Ultimately, however, PUR isn’t for every printer or every project. Calov says the decision hinges on being able to sell the job with an enhancement to the end product, or at a competitive price with traditional adhesives. “Hot melt is an old technology,” he says. “And PUR is a ‘Crazy Glue,’ but that doesn’t stick to everything, either.”


Small but strong
Customer requests recently prompted Duplo USA (Santa Ana, CA) to add PUR as an option for its MR-720 and Quadrimax perfect binders.

Both binders can be used for binding digitally printed jobs.

“The main reason [customers want PUR] is its holding strength,” explains product manager Anthony Gandara. “It also lets printers bind a greater variety of papers, including coated stocks.”

As Lightning Source, Amazon and other on-demand publishers expand their operations, Gandera predicts more interest in short-run binding equipment with PUR capabilities. “It all comes down to customer preference, but PUR is the ultimate glue,” says Gandara. “You can’t get any better than that.”

Single- and four-clamp binders
Duplo’s single-clamp MR-720 perfect binder is rated at 600 cph and accepts both flat sheets and signatures. It accommodates book thicknesses from two sheets to 1.97 inches and includes an automatic vacuum cover feeder and cover station and 1.63-inch top-feed design.

The four-clamp Quadrimax II perfect binder targets on-demand medium to long runs. Rated at 1,200 cph, it accepts flat sheets or signatures. Highlights include an automatic vacuum cover feeding mechanism with self-compensating, bevel-edged, cupped suckers.


Do it on demand
Digital printing is a growing market, and it follows that there must be a market for a PUR binding solution that can accommodate these short-run, toner-based jobs. “People are printing out a lot of coated mediums with their high-quality digital-color print engines,” says Bob Flinn, director of business development for Standard Finishing Systems (Andover, MA). “They’re introducing fuser oil to heavyweight stock, things that can inhibit good quality binding with EVA.”

Flinn reports that demand for PUR binding at this level is application-driven. “If someone is looking [to add] PUR,” says Flinn, “they have a need [that can’t be met with conventional adhesives or equipment]. The cost difference between PUR and EVA becomes a non-issue.” The Standard Horizon BQ-470 is a four-clamp perfect binder that produces 1,300 books per hour. An operator can store up to 100 jobs for repeat work. An operator can change over the automated system (book thickness, spine length, size, cover format, etc.) in about 30 seconds, and can handle many size changeovers within the course of a shift.

The machine utilizes an open tank system that slides out on a track rail system for easy draining and cleanup in five minutes. Standard’s PUR glue pot has a small capacity, to minimize waste. Users can switch between EVA and PUR in about five minutes.

Besides handling short- to ultra-short runs from one to 50, the BQ-470 produces a wider range of book thickness. It can bind anything from an eight-page signature to a 2.5-inch-thick book.

While it can be used as an ultra-short binder in the digital world, Flinn also says the BQ-470 also is a good fit for high-volume commercial printers or trade shops looking for a short-run machine. “It could be used for run lengths of 5,000 or less as a back-up to another multi-clamp or other binding line.”


Wanna know more?
Have you caught the PUR bug? AMERICAN PRINTER has plenty more where that came from! Check out:

  • “PUR in every glue pot?” April 2005
  • “Minding the binding,” October 2004
  • “PUR and perfect binding,” May 2003
These stories and more are available in our online archives.

Carrie Cleaveland is assistant editor of AMERICAN PRINTER. Contact her at