METHOD FOR MAKING PRINTING PAPER

FIELD OF THE INVENTION

The invention relates to a method defined in the preamble of claim 1 for making printing paper wherein paper in formed from a wood-containing raw material .

BACKGROUND OF THE INVENTION Known from the prior art are various methods for making different kinds of printing papers and printing paper products.

The business environment of the manufacture of paper and printed products has undergone deep changes. Production costs have increased as the price of energy and the prices of oil-based raw materials have risen. Furthermore, there has been overcapacity for certain paper grades in the field of papermaking, and printed products are forced to compete with prod- ucts of the electronic media.

In the manufacture of printing paper and printing paper products, it is known to optimize mainly the quality of the printing paper and the printing paper product.

OBJECTIVE OF THE INVENTION

The objective of the invention is to disclose a new and cost-effective method for making printing paper that fulfils the criteria of the client. Another objective of the invention is to improve the competitive strength of printing paper and printing paper products on the changing market.

SUMMARY OF THE INVENTION

The method according to the invention is characterized by what has been presented in the claims .

The invention is based on a method for making printing paper by forming the paper from a wood- containing raw material. According to the invention, the printing paper, preferably one that fulfils the requirements of the client, is formed by optimizing simultaneously the sensory properties of the printing paper, which include feel and visual properties, the quality of the printing paper and cost-effectiveness of papermaking and/or printing, and at least one variable is adjusted, the variable being selected from the group of variables: the raw material composition of the printing paper, properties of the raw materials, modes of processing the raw materials, papermaking parameters and printing parameters.

The sensory properties of paper refer to properties which are evaluated by the users of the pa- per or the printed product by their senses, such as how the products look, e.g. roughness, blistering or gloss, how the products smell or how the products feel when being touched and used, e.g. slipping, sticking, browsing and posture of the page, or the corresponding properties.

In this context, quality of the printing paper refers to the quality of the paper and quality of the print on the paper, which are common properties measurable from the paper or the printed product, and the visual appearance of the products.

In this context, the cost-effectiveness of papermaking refers to the fixed and variable costs of papermaking, capital costs relating to the manufacturing process, and the efficiencies and runnability of different steps of the process.

In this context, the cost-effectiveness of printing refers to the normal runnability properties, such as the printing speed, time efficiency of the printing machine, start-up time, number of web brakes, amount of maculature, need for washing and the corresponding properties, and the printing blanket and printing plate costs, consumption of the printing ink and other raw materials relating to printing.

In this context, the raw material composition of the printing paper refers to the raw material composition and the fiber composition.

In this context, the papermaking and printing parameters refer to selection of the manufacturing method and the process parameters, e.g. the adjustment and control parameters of the devices, the temperature, pressure, time, speed, web tension, feeding of the raw materials and additives and the corresponding parameters .

In this context, paper refers to any fiber- based paper or fiber product or the like. The paper may have been made from chemical pulp, mechanical pulp, chemimechanical pulp and/or mixtures thereof or the like. The paper may contain suitable fillers and additives and different kinds of surface treatment agents. The paper may be in the form of a web or a sheet, or in other form which is suitable for the purpose .

In this context, the printing paper may be any unprinted or printed printing paper or printing paper product. In one embodiment, the printing paper is a magazine paper.

The invention is specifically based on a method for making optimal printing paper or a printed product formed from the printing paper in a cost- effective manner with respect to the client' s requirements and to the quality of the product, and in par-

ticular to the sensory properties. In conjunction with the manufacture and printing of the paper, more than one variable are monitored, analyzed, adjusted and corrected to optimize the manufacturing of the print- ing paper and the printing paper product.

In one embodiment of the invention, paper which is suitable for use as printing paper is formed from a wood-containing raw material, and the paper is printed to form a printing paper product. In one embodiment of the invention, the printing paper contains mechanical pulp. In one embodiment, the printing paper is formed mainly from mechanical pulp. In this case, the proportion of the mechanical pulp in the paper is preferably more than 50% of the total amount of fibers. In one embodiment, the printing paper contains 30 to 50% mechanical pulp.

In one embodiment, the composition of the mechanical pulp and/or the treating method of the mechanical pulp is varied. In one embodiment, energy re- quirement of the mechanical pulp is optimized. Preferably, production of the mechanical pulp is arranged energy-effectively and/or cost-effectively by e.g. selecting an advantageous raw material or raw material composition. In one embodiment, the mechanical pulp is produced by one energy-saving solution or by a combination of a number of solutions. The energy-saving solutions may have been selected from the following: impact-based methods, die methods, methods based on the extruder technique, chemical and/or enzymatic pre- treatment methods, pressing and rubbing methods and the like. Treatment of the wood material, e.g. chips, reject, crushed wood or the like, may be performed by the above-mentioned methods or combinations thereof or alternatively by other suitable methods. The wood ma- terial is treated and refined to wood pulp in one or more steps. Refining mediators can be preferably used

in the production of mechanical pulp, the- mediators preferably being made from a hard material and contacted with the pulp to be refined to enhance the refining . In one embodiment of the invention, the mechanical pulp is produced at exceptionally low energy consumption.

In one embodiment, printing paper in which the grammage is arranged to be less than 90g/m ² , in one preferred embodiment less than 70g/m ² , is formed.

In one embodiment, the raw material composition of the printing paper is varied by using different raw materials, e.g. raw materials which are known per se in the art or different and new raw materials, in particular those which require little energy, are recycled and/or previously taken as refuse products, e.g. molder wood and dry wood raw materials. In one embodiment, the fiber composition is varied by using the desired fibers in the composition, which fibers may have been modified or treated in a desired and predetermined manner.

In one embodiment, the raw materials used in the manufacture of the printing paper and the amounts of the raw materials and the conditions of the manufac- turing process are selected based on the structural form of the web.

In one embodiment of the invention, additives are added to the wood-containing raw material, selected from the group: fillers, binders and chemicals. Any fillers, binders and chemicals known in the art may be used as the fillers, binders and chemicals.

In one embodiment of the invention, the filler is selected from the group: pigments known in the art, e.g. kaolines, talc, gypsum, calcium carbonates, titanium dioxides and plastic pigments; and novel fillers, such as on-site manufactured products, fines,

nano-class products, fillers modified from natural materials and composite products. The novel fillers may have properties which differ from the traditional fillers, e.g. natural binding capacity. The fillers modified from natural materials comprise e.g. pigments/fillers made from chemical pulp and wood. The composite products comprise e.g. fiber/pigment products, pigment/pigment products or pigment/polymer products . In one embodiment, a surface-modifiable printing paper is formed. In one embodiment of the invention, the surface of the paper is modified mechanically and/or chemically in conjunction with the manufacture or printing of the printing paper. In one em- bodiment, the surface of the printing paper is modified e.g. by coating and/or surface-treating before printing. In one embodiment, the surface-treatment may be a printing-type surface treatment. In one embodiment, the surface of the paper is modified mechani- cally by applying the surface-modification techniques known in the art, such as calendering or heat treatment .

In one embodiment, the techniques known in the art may be applied in the coating and surface- treatment. In one embodiment, the coating and surface- treatment agents may have been selected from the pigments, binders, additives and corresponding surface- treatment agents known in the art. In one embodiment, new types of raw materials may have been used in the coating and surface-treatment, such as on-site manufactured products, nano-class products, surface- treatment agents modified from natural materials and composite products. The products modified from natural materials comprise e.g. products made from chemical pulp and wood. The composite products comprise e.g.

fiber/pigment products, pigment/pigment products and pigment/polymer products.

In one embodiment, the paper is printed by the

Offset technique. Any technique known per se may be used as the Offset technique, e.g. the HSWO technique.

Alternatively, other printing techniques known in the art may be applied.

In one embodiment of the invention, the printing is controlled by applying tools used in pa- permaking to optimize the print quality and printing efficiency. In this context, printing efficiency refers to the pre- and post-treatment of the printing, the setup time of the apparatus and other corresponding functions, in addition to the actual runnability. In one embodiment, on-line data analysis methods, e.g. Wedge, sample analysis methods, e.g. Tapio analyses, high speed measurements, measurements by thermographic cameras, break camera measurements, web tension measurements, hardness measurements and/or the like are applied. Further, the print of the printing machine may be monitored e.g. by the tool presented in patent application FI 20055382. Also other suitable tools and methods may be applied.

In the method according to the invention, the analyses and adjustments may be made in an on-line or off-line manner or in other manners. The analysis devices may be positioned at the desired sites, typically at sites which are critical for the process.

In one embodiment of the invention, more than one variable are controlled at the same time, the variables being selected from at least one group of variables: the raw material composition of the printing paper, properties of the raw materials, modes of processing the raw materials, papermaking parameters and printing parameters. The adjustable variables may have been selected from one or more groups of variables.

When more than one variable are analyzed and corrected during the papermaking or the papermaking and printing, better optimization result is achieved.

The method according to the invention pro- vides considerable advantages compared to the prior art.

The method according to the invention pro ^¬ vides quality printing paper and printing paper prod ^¬ ucts cost-effectively. Thanks to the invention, printing paper and printing paper products may be made by optimizing different factors, such as the quality, price and proc- essability, by adjusting a number of components in the composition and production. Consequently, possible uses of different raw material and fiber compositions can be increased. Thanks to the invention, it is possible cost-effectively to make a product which is suitable for the client's needs.

The invention provides an industrially appli- cable, simple and affordable way of making printing paper. The method according to the invention is easy and simple to realize as a production process. Thanks to the invention, the production costs of the printing paper and the printing paper product can be more eas- ily adapted to the acquired price, so that an even more competitive printing product is provided.

The method according to the invention is suitable for use in the manufacture of different printing papers and printing paper products.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described in more detail by the following example.

Example 1

In this example, paper which is suitable for use as magazine paper and has a grammage of 50 to 60gsm is formed from mechanical pulp known per se and made using energy-saving technology. In this embodiment, partly dry chips are used for producing the mechanical pulp.

Pigment and normally used binders and chemi- cals are added to the wood-containing raw material. Preferably, the so-called novel pigments, such as on- site produced PCC, nano- and composite pigments, are used as the pigment. In one embodiment, organic pigment made from a wood-based raw material is used. Or- ganic pigment is lighter than the previously known stone-based pigments, which reduces the grammage of the printing paper product. The raw material composition included in the paper to be formed has been selected based on the costs, the paper grade and the de- sired properties of the paper.

The surface of the paper is coated with a mixture of an organic pigment composite product made on site.

The formed paper is printed by the Offset technique, in a preferred embodiment by the HSWO technique .

The manufacture, coating and printing of the paper are performed in manners known per se and are not described in any more detail in this context. In this example, the manufacture and printing of the printing paper are controlled by analyzing and varying the raw material and fiber composition, additives and the normal production parameters in the pa- permaking and printing by optimizing the cost- effectiveness of the method, the runnability and printability of the printing paper and the sensory

properties and waving properties of the printing paper and the printed product and by taking into consideration the requirements set to the product by the client . The tools known from papermaking, such as

Tapio analyses, Wedge, high speed and temperature measurements and break camera measurements are used for optimizing the runnability of the printing. Furthermore, the print of the printing machine is moni- tored. In addition to optimizing the runnability of the printing, the setting of the ink and water, the pre- and post-treatment of the printing and the surface treatment of the printed paper are controlled.

It is observed that magazine paper can be made in accordance with the client' s requirements at the same time cost-effectively and with quality results, the paper having good sensory properties, such as slipping, sticking, browsing of the page, sound, odor, roughness and visual properties. The product op- timization is easy when more than one variable are analyzed and adjusted simultaneously in both papermaking and printing. Furthermore, the tools known from papermaking can be successfully utilized in the printing to optimize runnability of the printing.

The method according to the invention is suitable in different embodiments to be used for making the most different kinds of printing papers and printing paper products. The invention is not limited merely to the example referred to above; instead many variations are possible within the scope of the inventive idea defined by the claims .