Despite facing increasingly tough competition from electronic media, it is estimated that the volume of printed information will double within the next five years as the information market expands¹. Factors such as recycling, speed, flexibility and cost are driving manufacturers to improve their papermaking operations, whilst the advent of digital printing, both in the office and at home, together with attention-grabbing consumer packaging in the retail sector, has led to the development of new technologies to improve the quality of the printed image. The pulp and paper industry represents approximately 10% of Spectris annual turnover and a number of Spectris companies are working with customers throughout this industry, from the start of the papermaking operation to the printing of high quality digital images.

Printing process and drivers for growth

The invention of paper goes back more than five thousand years to the Egyptians, who produced papyrus for writing on. Papyrus, a reed from the marshes of the Nile, was turned into sheets by laying strips cross-wise in alternate layers, wetting and then pounding them together to produce a rough, absorbent paper. The present process for making paper was invented by the Chinese two thousand years ago, but it wasn’t until the end of the eighteenth century that a papermaking machine was developed which made paper in a continuous web.

The basic principles of the papermaking machine are still in use today, albeit vastly improved. Although the papermaker's craft is still essential in designing and producing paper, technology has played a vital part in improving the efficiency with which it is manufactured and the quality of the end product. Machines are now capable of running at a rate of 2000 metres per minute and turning out large reels at a rate of around 1000 tonnes each day.

Meeting the demands of today’s consumers involves addressing a number of challenges. The primary factor is one of productivity. The growth in consumption of paper is steadily increasing: in the last 20 years, the combined usage of today’s top ten users has increased from 92 million tonnes to 208 million, with the highest growth experienced in China (597%) and South Korea (842%)². Environmental pressures are driving manufacturers to increase the amount of recycled material used, reduce harmful chemicals and recover waste water. Finally, printing the high quality images demanded by today’s competitive marketing and packaging industries requires higher quality paper stock. Meeting these demands means accurately monitoring and controlling every stage of the papermaking process. Several Spectris companies are providing precision instrumentation and controls to help customers at every stage in this process, from monitoring the amount of water in the initial pulp to UV technology used to create bright, flexible packaging.

BTG, together with its recently-acquired product range from Muetek, is a technological leader in the area of “wet end solutions”, with applications for measuring consistency, retention, brightness, drainage, gas and residual chemical content at the first stage of the papermaking process. Accurate control of pulp consistency prevents breaks in the web which can lead to costly downtime. The accuracy of consistency transmitters is such that one large North American mill estimated the payback period for installing BTG’s technology at their plant to be just one month. BTG’s products are also used in paper coating, where high-performance ceramic-tipped coating blades are ideal for this harsh environment. These blades last up to eight times longer than steel ones and require no run-in time. Fewer blade changes means less machine downtime and fewer variations in surface quality. With today’s coating machines running at speeds of 1,500 to 2,000 metres per minute, the savings in terms of time and energy are substantial.

NDC Infrared Engineering also has applications in the paper industry. On-line sensors provide continuous measurements in the coating and laminating process, enabling coatings such as film or adhesive to be deposited more precisely. The coatweight must be sufficiently robust to stand up to time and not be influenced by variations in paper grade or subtle reel to reel changes. Controlling coatweight allows manufacturers to operate as close to specification as possible, thereby reducing expensive adhesive and silicone usage whilst obtaining consistent product performance. In one application, the use of on-line gamma-based technology from NDC enabled a paper manufacturer in Australia to solve problems with the formation and bonding of 3-ply board, whilst cutting energy bills dramatically, with payback achieved within 12 months on energy savings alone.

The drive for higher yields has led to customers looking at how they can improve production efficiency. As papermakers seek to increase production volumes by speeding up the paper machine, monitoring the condition of critical machinery is essential to prevent expensive downtime. Brüel & Kjær Vibro’s vibration-based condition monitoring systems are used in paper mills to diagnose and predict machine faults. Catastrophic failures can result in huge material losses. In one particular application at a paper mill in the Czech Republic, use of Brüel & Kjær Vibro’s sophisticated software enabled the production speed of the papermaking machine to be increased whilst detecting and isolating individual defects. Any problems were then corrected during a scheduled shut-down without incurring unnecessary downtime.

At the printing stage, a range of techniques are used to produce high quality brochures, mailshots, and packaging. Flexible packaging, in particular, makes use of metallised film and foil, with the “shiny look” becoming commonplace as brand owners compete for attention on supermarket shelves. Fusion UV Systems works with many customers in the graphic arts and printing industry, where ultraviolet (UV) technology is increasingly being used to provide high gloss, scratch-resistant, decorative finishes. The benefits of UV curing (see In Perspective: UV Curing in previous issue) include improved image resolution, less set up time and waste and reduced energy costs. UV curing also offers environmental benefits compared with alternative technologies which are either toxic or emit solvent vapours. BTG is also present at this stage of the process, supplying ceramic-tipped doctor blades for the application of UV coating and for flexography printing on flexible packaging, as well as on board.

UV technology is also being used for digital printing, where the key advantage of UV ink-jet printers is the ability to print on any substrate, for example plastic, textiles and ceramics, as well as paper. Better print performance is also achieved using UV ink as a result of the instantaneous cure (drying) mechanism which reduces the dot gain associated with conventional ink-jet inks.

In the workplace, colour printers and photocopiers are increasingly being used to add interest to documents and presentations. The advent of digital technology means that short print runs of high quality materials are now economically viable. With no cost for film, plates or set up, and no minimum order, short runs of, for example, promotional material which was previously printed traditionally can be generated more cost effectively using digital printers. The growth in digital photography and home printing has also contributed to increased demand for colour printers. For manufacturers, the challenge lies in reducing production costs whilst maximising image quality. Producing consistent toner particles for use in colour printers and copiers is critical in achieving this. Malvern’s particle size and shape analyser uses patented technology which, as the result of experience in Japan, is already being written into a number of toner manufacturers’ patents as a reference measurement technique for quality control. For further details on this application click here.

As manufacturers seek to achieve improved productivity and flexibility yet reduce costs in an increasingly competitive consumer market, Spectris companies will continue to work with customers to develop new technologies to meet the challenges faced in getting from pulp to printed image.

1. Keith T. Davidson, President of Xplor International/Gartner Group report.
2. World Paper Use, National Association of Paper Manufacturers.

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