Pulp and Paper

INTRODUCTION

Pulp and paper products play an important role in all our lives. Art, literature, education, business, in fact most sectors of human endeavor depend on paper for sharing and recording ideas. Products are wrapped in paper, sanitary papers are used in toilet paper and baby diapers, paper is used in hospital gowns and masks and by-products from the pulp process can even be used to thicken ketchup and ice cream. The uses for pulp and paper products seem limitless as new specialty products are continually being developed.

The fibrous raw material used to make paper is called pulp and it is usually made from plants. Paper is made when a very dilute suspension of pulp is used to build up a network of fibres on a fine screen. In Canada the majority of pulp is made from wood, although pulps from non-wood plants such as hemp, flax, kenaf and bagasse are produced in small quantities.

In this article we will explore 1) the nature of wood fibre, 2) fibre processing and 3) pulp and paper products. To complete the picture we will examine the additional aspects of the pulp and paper industry story from the perspective of 4) environmental challenges and 5) competitiveness issues.

1. WOOD FIBRE

Plant cell walls are composed of cellulose which is the main material used to make paper. Wood contains high levels of these papermaking fibres and is the main pulp source utilized in North America. The structure and shape of the cellulose wood fibre varies from species to species and even within an individual tree. Fibre characteristics are also influenced by growing conditions. Fast growing trees have very different fibres than slow growing ones. It is the characteristics of the fibre that determine many of the properties of the finished paper.

Different fibres are used to make different kinds of paper. It is the fibre that gives paper its strength, suppleness, colour and chemical stability. During the sheet forming process the fibres are linked together, through the formation of hydrogen bonds, to make paper. It is these bonds that determine the strength of the paper. The two most important fibre characteristics that affect paper are the length of the wood fibre and the thickness of the fibre walls.

Canfor's pulps and papers are word renowned for the fibre strength of our northern fibre base of spruce, pine and fir species.

• As a general rule, the longer the fibre, the greater the tearing strength of the paper. Southern yellow pine from the United States is an example of a long fibre. These fibres are used in packaging papers, paperboards and stationery.
• Short fibres, such as those in birch or aspen, produce smooth, lower strength papers. These fibres are widely used in grades such as printing paper and photocopy paper.
• Fibres with thick fibre walls, such as Douglas fir, produce an open, absorbent and bulky paper with a low bursting and tensile strength and a high tearing resistance. These properties are important in products like filters, absorbent products and some types of tissue.
• Fibres with thin walls, such as spruce, collapse easily into a ribbon-like state allowing a greater area of contact between fibres. These contact areas are where the bonding between fibres takes place. The papers made with them are smoother, low in porosity and have a very high tensile strength. Typically, these fibres are used to reinforce mixtures of other fibre types, allowing very light but strong papers to be produced. Typical grades made using these fibres include magazine papers and light-weight strong sheets such as bible papers.
• The thinnest walled fibre of all is western red cedar. Paper made from this fibre is almost cloth-like in feel. It is used to make products such luxury tissue, lab coats and surgical gowns.

The fact that wood fibres can vary so much means that in processing, mills must separate out the different kinds of wood chips to use for different kinds of pulps.

2. PROCESSES

Wood fibres are held tightly together by a chemical called lignin. Wood chips are processed in order to free the wood fibres from the lignin so they can be made into paper products. Pulping is the process by which wood is reduced to its individual fibres. Incredible as it may seem, there can be 3-4 million fibres in a single gram of a typical softwood pulp! Breaking down the wood into fibres can be accomplished by mechanical or chemical processes or combinations of both.

Yield is the term used to describe the proportion of the original wood that is converted into the various forms of pulp. Yields vary enormously, and the lower the yield, the greater the purity of the finished pulp. Some paper grades can use the high yielding pulps, while other paper grades require the purer low yield pulps. For example the roughly 96% yield of the thermomechanical process produces pulps suitable for newsprint while the 43% yield of kraft chemical pulping can be made into fine quality papers such as those used in fine stationery. Thermomechanical Pulping

Thermomechanical pulping (TMP) uses pressurized steam, heat and grinding to separate the wood fibres. The lignin is not removed, but the fibre cells are ground up so that the cellulose in the inner layers of the fibre cell is exposed. A very high percentage of the original wood components are retained in the final product, resulting in a high efficiency or yield. Overall, the capital cost for building these mills is substantially lower than for a chemical pulp mill. However, the pulps produced are lower in strength, and tend to yellow with age. Further, the process uses large amounts of electricity. TMP pulp can be used to make paper, newspaper and paperboard products. Chemical Pulping

Canfor's mills use the chemical pulping process, which produce pulps that use a greater quantity of wood fibre per tonne of product. The complicated process makes the capital costs to build a chemical pulp mill higher and the expensive waste water treatment systems required add greatly to the cost. However, the strength and brightness of the pulp is unsurpassed.

In kraft chemical pulping wood chips are boiled with sodium hydroxide and sodium sulphide to remove the lignin and separate the cellulose fibres in the wood from each other. This process has two significant advantages over other methods. The cooking liquor can be completely recycled within the process and the resulting fibres have the highest strengths of any fibres produced. This is the most common chemical pulping process used today. The kraft process produces a strong, high quality pulp which can be used to make products as diverse as bible papers and food packaging. It is also used to strengthen paper products containing other weaker fibres or recycled fibres. An example of such a use is in the making of magazine papers.

In sulphite chemical pulping various forms of sulphite-based liquors are used to digest the wood chips. This process can be used to produce paper pulps and chemical stock for other cellulose products. This is an older method of pulping which is less economical and can have more pollution consequences than the kraft process. The fibres produced are often used when high chemical purity is needed, such as in the making of photographic paper.

Bleaching

Chemical pulping turns the wood pulp brown in colour. Although this is fine for such packaging as cardboard and some paper bags, whiteness is an important characteristic in papers used for printing or high quality packaging. Bleaching is used to whiten and purify the pulp fibres. How much bleaching is required depends on the end product that will be manufactured from the pulp. Bleaching, however, weakens the wood fibre. Different paper products have different requirements for the balance between strength and whiteness. To meet this range of needs, mills produce a variety of pulps such as fully bleached, semi-bleached and unbleached.

In the past, chlorine was used to bleach pulp. It was later found that this chemical contributed to the formation of chlorinated dioxins and furans, a pollution hazard. Two alternate processes that were developed are:

• Totally Chlorine Free
  (TCF) which uses hydrogen peroxide and oxygen, and
• Elemental Chlorine Free
  (ECF) which uses chlorine dioxide, oxygen and hydrogen peroxide.

The TCF pulp bleaching process was initially thought to be the most environmentally sound process. However, recent research has compared the environmental impact of the entire "life cycle" of both bleaching processes. The results indicated that ECF is not only more efficient, but it can also be every bit as environmentally friendly as the TCF process. The chlorine dioxide used in the ECF process does not create the dioxin hazard that using elemental chlorine created and it produces more pulp from a set amount of wood than ECF.

(For more information on this subject and Life Cycle Assessment in general, please see the Environment section of this site where you can download a copy of our LCA)

3. PRODUCTS

Pulps

Pulp mills produce a variety of pulps. The variety is due to the types of wood chips, different pulping processes and the range of bleaching used. Each combination produces a pulp that has a different set of characteristics. Canfor mills work with customers to find the best technical fit between the type of pulp they produce and the processes the paper manufacturers will be using. By tailoring the pulp process to fit with the papermaking process, the pulps become value-added products rather than just bulk commodity products.

Many pulp mills are integrated with paper mills so the pulps go right into the paper side of the operation. Other companies sell their pulps to paper mills. This is called Market Pulp. Another product made from pulp mills is called dissolving pulp. These pulps are converted into non-paper products such as rayon, cellophane, camera film, thickeners for foods, plastics, explosives, artificial hair and sausage casings ( for a more extensive list see Tree Trivia).

Papers

Papermaking today is a combination of high technology and craftsmanship. Although a common technology is used to make most papers, the broad range of pulps available and the flexibility of the manufacturing process produces a huge range of properties and qualities. There are literally hundreds of paper grades. To look at it simply, most papers fall into 3 broad functional groups:

1. Communication, informational and literacy purposes: For example, newsprint, catalogues, publications and stationery.
2. Commercial packaging, industrial and constructional use: For example, bags, construction paper and cardboard.
3. Personal or sanitary purposes: For example, sanitary tissues, towelling and wrapping tissue.

4. ENVIRONMENTAL CHALLENGES

Protecting the environment is a high priority for pulp and paper mills in Canada. Environmental challenges for mills include increasing the efficient use of fibre, the disposal of solid waste, improving air and water emissions and the very important issue of sustainability of the forestry operations.

There has been significant progress by the Canadian industry in reducing environmental impact over the last few years. For example:

• The creation of Dioxins and Furans are now virtually eliminated.
• Biochemical oxygen demand (BOD) has declined 75% between 1979-1993.
• Total suspended solids (TSS) discharges have declined by 85%.
• Water usage has dropped by 60%.

Many customers are environmentally conscious and are demanding high environmental standards from manufacturers. This has led to the development of international standards that certify the level of stewardship a mill or forestry operation has achieved. These standards are regularly audited to ensure compliance.

The 3 main certification programs are ISO, CSA and FSC.

• ISO: The International Organization for Standardization is an international non-profit organization that has developed certification standards of precise criteria to be used consistently around the world. These rules or guidelines ensure that materials, products, processes and services are fit for their purpose. Standards have been developed for both product and environmental quality.
  The ISO 9001 standard represents an international consensus on quality management practices. The aim is to ensure that the organization can consistently deliver the product or services that meet the client’s quality requirements.
  The ISO 14001 standard is a management tool to control the environmental impact of a company’s activities on the environment. An environmental management system sets environmental objectives and targets for achievement. External audits ensure that the environmental management system is operating effectively.
• CSA: The Canadian Standards Association is the official standards setting body for Canada. In 1996 they produced a Sustainable Forest Management standard based on a comprehensive set of internationally recognized sustainable forestry criteria. The CSA standard includes an environmental management system consistent with the ISO 14001 standard and also includes a broader range of public participation and other sustainable forestry elements.
• FSC: The Forest Stewardship Council is an international non-profit organization that has developed a forestry standard based on an international set of principles and criteria to promote environmentally responsible, socially beneficial and economically viable forest management. The FSC has also developed a "chain of custody" labelling program to guarantee that the wood products have come from a forest which has been evaluated and certified as meeting the standard. This is currently the only forest certification system to offer a label.

In conjunction with certification, many pulp and paper companies also offer an Environmental Profile Data Sheet. The purpose of this activity is to encourage dialogue with customers and promote continuous improvement. This data sheet offers customers detailed and objective information on the environmental footprint of the products they use. This third-party verified form provides comprehensive information on the life cycle environmental attributes of pulp and paper products.

Canfor's forestlands are certified to the ISO 14001 standard and approximately 1.5 million hectares are certified to the CSA standard. Our pulp and paper mills are all ISO 9001 certified.

5. COMPETITIVENESS ISSUES

The global marketplace is changing dramatically for the Canadian pulp and paper producer as a result of:

• new low cost competition from South America and Asia,
• industry consolidation,
• high investor expectations,
• increased customer demands, and
• heightened public awareness of the environment.

These new conditions are part of a global wave of change that is forcing companies to develop innovative strategies and find new ways to stay competitive.

Traditionally, pulp producers have focussed on increasing productivity and cutting costs. This production-oriented strategy has led to a highly cyclical industry. Most analysts suggest that a new focus on creating customer value is the future path for Canadian industry. This value-added focus could produce greater profit margins in the long term.

Part of the response to change must include a research component. R&D investment is essential in order to improve in the following areas:

• productivity
• product quality
• wood and energy efficiency
• higher value products
• new manufacturing processes
• reducing environmental impact.

As research into technology and processes becomes operational, a further investment in people is imperative. Skill requirements for workers are continuously increasing. The importance of a company’s ability to attract and retain highly skilled workers cannot be undervalued. Ongoing training and educational opportunities provide an important competitive edge.

The corporate culture or internal environment of a company plays a role in competition as well. The culture must not only support innovation and teamwork for product and market development, but also for working with well-informed global stakeholders. How companies deal with environmental problems and labour issues is shared around the world in seconds. The company’s response will be evaluated by both current and potential customers.

SUMMARY

We all use paper products daily. They are an integral part of our society. The pulp and paper industry also produces significant economic benefits and levels of employment that are important for many communities.

The basic unit for all pulp and paper products is the tiny wood fibre. Different species of wood have different fibre characteristics. It is this variety in fibre characteristics that produces the broad range of paper qualities that we enjoy, from soft, absorbent tissue to tough, strong kraft paper.

Wood fibres are processed into pulp by chemical or mechanical methods. These industrial processes must be managed with precision and care to ensure high quality products and a clean environment. Consumer and stakeholder demands continue to raise the level of both quality and environmental standards.

The global business environment is changing, forcing Canadian producers to transform in order to survive. How companies and customers look at products, markets and environmental impact is evolving. Value-added products, niche markets, customer relations, research and development, teamwork and employees skill levels are all part of the industry response to the next generation of world trade.

For more information on Canfor's pulp and paper products go to the products section of the web site and click on Pulp and Paper or see the following Tree School library articles