EP3055454A1

EP3055454A1 - Method for manufacturing a paper, a paper and its use, a furnish and a wood based composition

Info

Publication number: EP3055454A1
Application number: EP14852845.8A
Authority: EP
Inventors: Mika RÄTY; Jouko Lehto; Peter SANDÅS; Jussi VENTOLA; Tarja Sinkko; Janne Varvemaa; Mika V KOSONEN; Isko Kajanto
Original assignee: UPM Kymmene Oy
Current assignee: UPM Communication Papers Oy
Priority date: 2013-10-11
Filing date: 2014-10-09
Publication date: 2016-08-17
Also published as: EP3055454A4; WO2015052380A1

Abstract

The invention relates to a method for manufacturing a paper. According to the invention,the paper (10) is formed from a furnish (6) which comprises pulp (1) including at least mechanical pulp (8), a wood based component (2) and a strength chemical (3), the wood based component (2) and strength chemical (3) are mixed for forming a wood based composition, and the furnish (6) is formed from the pulp comprising the wood based composition. Further, the invention relates to a corresponding paper and its use, a furnish and a wood based composition.

Description

METHOD FOR MANUFACTURING A PAPER, A PAPER AND ITS USE, A FURNISH AND A WOOD BASED COMPOSITION

FIELD OF THE INVENTION

The invention relates to a method for manu^¬ facturing a paper. Further, the invention relates to a paper and its use. Further, the invention relates to a furnish and a wood based composition. BACKGROUND OF THE INVENTION

Known from the prior art are different paper products and processes for manufacturing them from fiber-based pulp. The addition of different filler, pig^¬ ment and additional components to fiber-based pulp is known. Typically, different inorganic, such as miner^¬ al-based, pigments and fillers are used. Known from the prior art is also the addition of pigments and fillers of organic origin to pulp to manufacture pa^¬ per .

OBJECTIVE OF THE INVENTION

The objective of the invention is to disclose a new method for manufacturing a paper to form a new type paper product. Further, the objective of the in- vention is to disclose a lighter product. Further, the objective of the invention is to disclose a new type furnish formed from a new type of material composi^¬ tion. Further, the objective of the invention is to disclose a new wood based composition.

SUMMARY OF THE INVENTION

The method for manufacturing a paper according to the present invention is characterized by what is presented in claim 1. The paper according to the present invention is characterized by what is presented in claim 11.

The use of the paper according to the present invention is characterized by what is presented in claim 13.

The furnish according to the present invention is characterized by what is presented in claim 14.

The wood based composition according to the present invention is characterized by what is present^¬ ed in claim 15.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are included to provide a further understanding of the invention and constitutes a part of this specification, illus^¬ trate some embodiments of the invention and together with the description help to explain the principles of the invention. In the figures:

Fig. 1 is a flow chart illustration of a method according to one embodiment of the present in^¬ vention, and

Fig. 2 is a flow chart illustration of a method according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the method of the present invention a paper 10 is formed from the furnish 6 which comprises at least pulp 1 including at least mechanical pulp 8, a wood based component 2 and a strength chemical 3. The wood based component 2 and strength chemical 3 are mixed in the pulp 1 for forming a wood based composi^¬ tion, and the furnish 6 is formed from the pulp 1 com- prising the wood based composition. Preferably, the wood based component 2 is arranged into the furnish 6 to replace inorganic filler. Then the paper with good quality and low basis weight can be formed.

In one embodiment the method is used for forming a printing paper. In one embodiment the method is used for forming a coated paper. In one embodiment the method is used for forming a coated printing pa^¬ per .

Some method embodiments of the present inven^¬ tion are shown in figures 1 and 2.

In this context, the paper refer to any paper or paper product which is formed from a fiber-based composition, such as from a furnish. The paper may be any paper, paperboard, cardboard or the like. The pa^¬ per may contain suitable pigments, fillers and addi- tives and different surface treatment and coating agents. The paper may be in the form of a web or a sheet or in other form suitable for the purpose of use. The furnish refers to any furnish comprising pulp and desired fillers, pigments and additives. The fur- nish is formed from pulp composition in the mixing vessel 12 of the paper manufacturing. The furnish includes at least mechanical pulp, and it may include also other pulp or different combinations of pulps. Further, the furnish includes the wood based composi- tion including a wood based component and a strength chemical .

In this context, the pulp includes any pulp but at least mechanical pulp. The pulp may be formed from any raw stock. The pulp may be selected from the group consisting of mechanical pulp, chemical pulp, chemimechanical pulp, recycled pulp, pulp from non- wood raw stock and their combination. The mechanical pulp may be any mechanical pulp or chemimechanical pulp or their combination. The pulp can include one or more pulp components. In one embodiment other pulp is added into the mechanical pulp. In one embodiment other pulp is added into the mechanical pulp in connection with the treatment of the pulp and/or the mixing vessel of the furnish.

In one embodiment the furnish includes mechani^¬ cal pulp between 10 to 100, preferably 20 to 100 %, by weight of dry weight of the base paper furnish. In one embodiment the pulp includes mechanical pulp between 25 to 100 %, preferably 60 to 90 %, more preferably 70 to 85 %, by weight of dry weight of the pulp. Preferably, an amount of the mechanical pulp is increased in com- parison with the reference papers.

In this context, the wood based component means any wood containing component which may be used as a pigment or filler in the pulp. The wood based com^¬ ponent may be a wood based pigment or filler, or wood based pigment type or filler type material. The wood based component includes wood fibres, fines, ground wood particles or their combinations. The wood based compo^¬ nent may be formed by any suitable method, such as by grinding and/or other suitable treatment. In one embod- iment the wood based component consists of mainly parti^¬ cles which are passed a sieve with 200 mesh, as deter^¬ mined by SCAN-CN 6:05 standard. The wood based compo^¬ nent can include one or more component. The wood based component can be in the form of dispersion, slurry, solution, dry composition or the like.

In one embodiment the wood based component 2 is formed from wood based raw material in a separate pro^¬ cess, and the wood based component 2 is fed into the pulp 1. The wood based component may be formed by any suitable method, such as by grinding and/or other suita^¬ ble treatment, e.g. by means of some method presented in patent applications WO 2009080894 (teidan viite 2133), WO2009144372 (2159), WO 2009144373 (2009) and/or WO2013034811 (11094) . In one embodiment the wood based component is fibre containing component. In one embodi^¬ ment the wood based component contains fibres and/or fines . In one embodiment the wood based component 2 is formed in connection with the manufacture of the pulp, preferably the mechanical pulp 8, e.g. in a refining or in another process step, and then the pulp comprises the wood based component. In one embodiment the wood based component consists of pigment type fines, e.g. fines of ground pulp or fines of refiner groundwood. In one em^¬ bodiment the wood based component is fibre containing component. In one embodiment the wood based component contains fibres and/or fines.

In one embodiment the wood based component 2 is a wood based pigment which contains wood fibres and/or fines .

In this context, the strength chemical means any strength component which improves strength in the pulp. The strength chemical may include any strength chemical, strength improving agent or the like. The strength chemical can be in the form of dispersion, slurry, solution, dry composition or the like.

In one embodiment the strength chemical 3 in^¬ cludes nanofibrillated cellulose. In one embodiment the strength chemical includes nanofibrillated cellu^¬ lose between 50 to 100 % by weight of the dry weight of the strength chemical. The strength chemical may contain from more than 0% to less than 100w-% of nano- fibrillated cellulose. In addition to nanofibrillated cellulose, the strength chemical may contain other suitable components, e.g. other strength chemical, ad^¬ ditives and/or fibers that may be formed from any plant-based raw material. In one embodiment the strength chemical consists mainly of nanofibrillated cellulose .

In one embodiment the nanofibrillated cellu^¬ lose with 0.5 to 2.5 %, in one embodiment 0.8 to 2.0 %, solution consistency is introduced to the pulp.

In one embodiment, nanofibrillated cellulose may be in the form of a dispersion, e.g. in a gel-type or gelatinous form or in the form of a diluted disper^¬ sion, or in the form of a suspension, e.g. aqueous suspension. Preferably, the nanofibrillated cellulose is in the form of an aqueous suspension.

Nanofibrillated cellulose in this context means cellulose consisting of nanofibrils and/or micro^¬ fibrils, such as a set of isolated cellulose nanofibrils and/or nanofibril bundles derived from a cellulose raw material. Cellulose fibers contain nanofibrils that are strand-like structural components of the cellulose fi^¬ bers. The cellulose fiber is provided fibrous by fibril- lating. The aspect ratio of nanofibrils is typically high; the length of individual nanofibrils may be more than one micrometer and the number-average diameter is typically less than 20nm. The diameter of nanofibril bundles may be larger but generally less than lym. The smallest nanofibrils are similar to the so-called ele^¬ mentary fibrils, the diameter of which is typically from 2 to 4 nm. The dimensions and structures of nanofibrils and nanofibril bundles depend on the raw material and production method.

Nanofibrillated cellulose may have been formed from any plant-based raw material, e.g. wood-based raw material, such as hardwood raw material or softwood raw material, or other plant-based raw material containing cellulose. Plant-based raw materials may include e.g. agricultural waste, grasses, straw, bark, caryopses, peels, flowers, vegetables, cotton, maize, wheat, oat, rye, barley, rice, flax, hemp, abaca, sisal, kenaf, jute, ramie, bagasse, bamboo or reed or their different combinations .

Nanofibrillated cellulose may also contain hemicellulose, lignin and/or extractives, the amount of which depends on the raw material used. Nanofibrillated cellulose is isolated from the above-described raw ma^¬ terial containing cellulose by an apparatus suitable for the purpose, e.g. a grinder, pulverizer, homoge- nizer, fluidizer, micro- or macrofluidizer, cryo- crushing and/or ultrasonic disintegrator. Nanofibril- lated cellulose may also be obtained directly by a fermentation process using microorganisms e.g. from the genera Acetobacter, Agrobacterium, Rhizobium, Pseudomonas or Alcailgenes, most preferably from the genera Acetobacter and most preferably of all from the species Acetobacter xylinum or Acetobacter pasteuri- anus. Raw materials of nanofibrillated cellulose may also include for example the tunicates (Latin: tunica- ta) and organisms belonging to the chromalveolate groups (Latin: chromalveolata) , e.g. the water molds (Latin: oomycete) , that produce cellulose.

In one embodiment, nanofibrillated cellulose may be any chemically or physically modified derivative of cellulose or nanofibril bundles consisting of nano- fibrils. The chemical modification may be based on e.g. a carboxymethylation, oxidation, esterification and etherification reaction of the cellulose molecules. The modification may also be carried out by physical adsorp^¬ tion of anionic, cationic or non-ionic agents or their combinations to the surface of cellulose. The modifica^¬ tion may be performed before, during or after the manu- facture of nanofibrillated cellulose.

Nanofibrillated cellulose may be formed from a cellulose-based raw material by any manner known per se in the art. In one embodiment, nanofibrillated cellu^¬ lose is formed from a dried and/or concentrated cellu- lose raw material by fibrillating . In one embodiment, the cellulose raw material has been concentrated. In one embodiment, the cellulose raw material has been dried. In one embodiment, the cellulose raw material has been dried and concentrated. In one embodiment, the cellulose raw material has been chemically pretreated to disinte^¬ grate more easily, i.e. labilized, in which case nano- fibrillated cellulose is formed from the chemically la- bilized cellulose raw material. For example, a N-oxyl (e.g. 2 , 2 , 6, 6-tetramethyl-l-piperidine N-oxide) mediated oxidation reaction provides a very labile cellulose raw material that is exceptionally easily disintegrated into nanofibrillated cellulose. Such a chemical pretreatment is described for example in pa^¬ tent applications WO 09/084566 and JP 20070340371.

The fibrils of nanofibrillated cellulose are fibers that are very long relative to the diameter. Nan- ofibrillated cellulose has a large specific surface ar^¬ ea. Therefore, nanofibrillated cellulose is able to form multiple bonds and bind many particles. In addi^¬ tion, nanofibrillated cellulose has good strength prop- erties.

In one embodiment, nanofibrillated cellulose is mainly nanocellulose . Nanocellulose consists at least mainly of nano-size class fibrils, the diameter of which is less than lOOnm but the length of which may also be in the ym-size class or below. Nanofibrillated cellu^¬ lose may refer to any nanofibrillated cellulose, nano- fibril cellulose, nanofibers of cellulose, nanoscale fi^¬ brillated cellulose, microfibril cellulose or microfi^¬ brils of cellulose. Preferably, nanofibrillated cellu- lose in this context does not mean so-called cellulose nanowhiskers or microcrystalline cellulose (MCC) .

In this context, the wood based composition means any composition, mixture, composite or the like which includes at least the wood based component 2 and the strength chemical 3. The wood based composition can be in the form of dispersion, slurry, solution, dry composition or the like.

In one embodiment, the mechanical pulp 8 is formed from raw stock in a refining step 4. In one em- bodiment, other pulp 9 is added into the mechanical pulp 8 after the refining step 4 in order to form pulp 1. In one embodiment, the mechanical pulp is used as such as pulp 1. In one embodiment, other pulp 9 is added into the pulp 1 in the mixing vessel 12 of the furnish 6.

In one embodiment, the wood based component 2 is formed during the refining step 4, preferably dur^¬ ing the forming of the mechanical pulp 8. In one embod^¬ iment, the strength chemical 3 is added into the pulp 1 which contains the wood based component 2.

In this context, the refining step 4 means any refining step, pulping step, defibering step, other pulp treatment step or their combination. In one embodiment, the refining step comprises a defibering step or a pulping step, e.g. a pulper. In one embodi^¬ ment, fines are formed in the refining step. Any suit- able devices known in the art may be used in the re^¬ fining step.

In one embodiment, the wood based component 2 and strength chemical 3 are added into the pulp 1.

In one embodiment, the wood based component 2 is added into the pulp 1. In one embodiment, the wood based component is added into the pulp after the re^¬ fining step 4. In one embodiment, the wood based com^¬ ponent is added into the pulp before the post-refining step 5. In one embodiment, the wood based component is added into the pulp during the post-refining step 5. In one embodiment, the wood based component is added into the pulp between two post-refining steps 5. In one embodiment, the wood based component is added into the pulp during more than one post-refining step 5.

In this context, the post-refining step 5 means any post-refining step, in which mixing, refining, grinding, defibrating, homogenisation, other pulp treatment or their combination can be made. In one embodiment, the post-refining step comprises a mixing step, e.g. a mixing device, in which refining or grinding is also made. In one embodiment, additional fines are formed in the post-refining step. Any suita- ble devices known in the art may be used in the post- refining step. In one embodiment, the post-refining is carried out in one or more than one post-refining step .

In one embodiment, the strength chemical 3 is added into the pulp 1. In one embodiment, the strength chemical is added into the pulp after the refining step 4. In one embodiment, the strength chemical is added into the pulp before the post-refining step 5. In one embodiment, the strength chemical is added into the pulp during the post-refining step 5. In one embodiment, the strength chemical is added into the pulp between two post-refining steps 5. In one embodiment, the strength chemical is added into the pulp at one stage. In one embodiment, the strength chemical is added into the pulp at more than one stage. In one em^¬ bodiment, the strength chemical is added into the pulp during more than one post-refining step 5.

In one embodiment, the wood based component 2 is added into the pulp 1 and after that the strength chemical 3 is added into the pulp 1. In one embodi^¬ ment, the wood based component 2 and the strength chemical 3 are added into the pulp 1 simultaneously. In one embodiment, the strength chemical 3 is added into the pulp 1 and after that the wood based compo^¬ nent 2 is added into the pulp 1.

In one embodiment, the wood based composition is formed on-line from the wood based component 2 and the strength chemical 3 during the treatment of the pulp 1. In one embodiment the strength chemical 3 is added into the pulp 1 which contains the wood based component 2, and the strength chemical 3 and the wood based component 2 are mixed in order to form the wood based composition. In one embodiment the wood based component 2 and strength chemical 3 are added into the pulp 1, and the strength chemical and the wood based component are mixed in order to form the wood based composition .

In one embodiment, the wood based composition containing the wood based component 2 and the strength chemical 3 is added into the pulp 1. In one embodiment the wood based component 2 and strength chemical 3 has been mixed, preferably in a separate process step or in a separate process, for forming the wood based com^¬ position, and the wood based composition is added into the pulp 1. In one embodiment, the wood based composi^¬ tion is added into the pulp after the refining step 4. In one embodiment, the wood based composition is added into the pulp before the post-refining step 5. In one embodiment, the wood based composition is added into the pulp during the post-refining step 5. In one embodiment, the wood based composition is added into the pulp between two post-refining steps 5. In one embodi^¬ ment, the wood based composition is added into the pulp during more than one post-refining step 5.

In one embodiment the furnish 6 comprises ad^¬ ditives, other chemicals or other agents, e.g. fixa^¬ tives and other process chemical, which may be added during the treatment of the pulp 1 or in the mixing vessel of the furnish. In one embodiment the furnish comprises inorganic pigment or filler which may be added after the treatment of the pulp or in the mixing vessel of the furnish.

In one embodiment, the furnish 6 contains the wood based component 2 between 5 to 60 %, preferably 20 to 50 %, by weight of dry weight of the mechanical pulp .

In one embodiment, the furnish 6 contains the strength chemical 3 between 0.1 to 3 %, preferably 0.3 to 2 % and more preferably 0.5 to 1.5 %, by weight of dry weight of the furnish fibers.

In one embodiment reject material comprising coated paper reject is added into the furnish 6 before the manufacture 11 of the paper 10, e.g. in the mixing vessel of the furnish.

Preferably, the paper 10 of the invention com^¬ prises pulp 1 including at least mechanical pulp 8 and wood based composition containing the wood based compo^¬ nent 2 and strength chemical 3. The paper 10 has been formed from a furnish 6 which comprises pulp including at least mechanical pulp, a wood based component and a strength chemical; the wood based component and strength chemical has been mixed for forming a wood based composition; and the furnish has been formed from the pulp comprising the wood based composition. In one embodiment the paper 10 is coated to form a coated paper, e.g. a coated printing paper. The paper may be used as a printing paper.

In the present invention the paper 10 is formed from mechanical pulp 8 containing furnish 6, and the wood based composite composition is formed from wood based component 2, preferably wood based pigment type component, and nanofibrillated cellulose 3 during the pulp treatment.

Technical effects of the invention are that increased strength properties and lower air permeabil^¬ ity can be achieved in paper. Improved strength prop- erties give the possibility to increase the amount of wood pigment in the paper which further improves opti^¬ cal and printing properties of the paper. Lower air permeability in turn gives better coater runnability in terms of better coating hold out especially in LWC grades.

An additional technical effect of the inven^¬ tion is that an amount of inorganic pigment or filler can be decreased in the furnish and the paper. By means of the wood based component and the wood based composition may be replaced inorganic pigments and fillers. When inorganic pigments and fillers are re^¬ placed by wood based materials, the environmental load can be reduced, and recyclability of paper can be im^¬ proved. An additional technical effect of the inven^¬ tion is that an amount of mechanical pulp may be in^¬ creased in the paper. Further, an amount of wood based material can be increased in the paper. Further, total ash content decreases.

An additional technical effect of the present invention is that a lighter paper product with good quality properties can be achieved. The paper product of the present invention may be 10 - 15 % lighter than a corresponding paper product with inorganic pigment or filler. However, the paper of the invention has same quality than the heavier paper. Further, the paper of the invention feels like the heavier paper, e.g. page turnability, thickness and slipperiness of magazine, catalog or flyers.

The method according to the present invention is suitable for use in the manufacture of the differ^¬ ent papers. In the present invention, different wood based components and the strength chemical, such as nanofibrillated cellulose can be utilized in the paper manufacturing .

EXAMPLES

The invention is described in more detail by the following examples with reference to accompanying figures 1 to 2.

Example 1

In this example, which is shown in figure 1, a paper 10 is formed in the paper manufacturing 11 from a furnish 6.

The furnish 6 is formed in a mixing vessel 12, and the furnish 6 comprises pulp 1 including at least mechanical pulp 8 and wood based composition in^¬ cluding a wood based component 2 and a strength chemi- cal 3. Further, the furnish may include other pulp 9 which may be added into the pulp 1 before the post- refining 4 or in connection with the mixing vessel 12.

The mechanical pulp 8 is formed by refining raw stock 7 in a refining step 4. The wood based component 2 is formed during the refining step 4 of the mechanical pulp 8. The mechanical pulp 8 is used as pulp 1 as such, or other pulp 9 is added into the mechanical pulp 8 for forming pulp 1. The strength chemical 3 is added into the pulp 1 containing the wood based compo^¬ nent 2 before a post-refining step 5. The wood based component 2 and strength chemical 3 is mixed for form^¬ ing a wood based composition in the pulp 1. The pulp 1 comprising the wood based composition which contains the wood based component 2 and strength chemical 3 is fed in the mixing vessel 12.

Example 2

In this example, which is shown in figure 2, a paper 10 is formed in the paper manufacturing 11 from a furnish 6.

The furnish 6 is formed in a mixing vessel 12, and the furnish 6 comprises pulp 1 including at least mechanical pulp 8 and wood based composition in- eluding a wood based component 2 and a strength chemi^¬ cal 3. Further, the furnish may include other pulp 9 which may be added into the pulp 1 before the post- refining 4 or in connection with the mixing vessel 12.

The mechanical pulp 8 is formed by refining raw stock 7 in a refining step 4. The mechanical pulp 8 is used as pulp 1 as such, or other pulp 9 is added into the mechanical pulp 8 for forming pulp 1. The wood based component 2 and strength chemical 3 are added in^¬ to the pulp 1 before a post-refining step 5. The wood based component 2 and strength chemical 3 is mixed for forming a wood based composition in the pulp 1. The pulp 1 comprising the wood based composition which contains the wood based component 2 and strength chem^¬ ical 3 is fed in the mixing vessel 12. Example 3

In the test made by example 1, a coated paper 10 according to the invention was formed from pulp 1 comprising pressurized ground wood 8 and soft wood kraft 9, and the pulp contained 10 %-unit less chemi- cal pulp than the pulp of the reference paper. The pressurized ground wood included wood pigment type particles 2 which were treated with nanofibrillated cellulose 3, dosage 0 to 1.0 % calculated from base paper furnish. Coating color was optimized in terms of RG printability .

Different properties were determined from the obtained paper. The results are presented in Table 1. The results compared with results obtained by a corre^¬ sponding reference paper which is a typical paper con- taining soft wood kraft and pressurized ground wood and inorganic filler, and which is 15 % heavier paper.

Table 1

Test paper Reference paper

Basis weight, 43.4 51.1

g/m2

Thickness, ym 36 39

Brightness ISO 68.9 70.8

tS , ~6

Opacity, % 90.3 90.2

Heliotest ts, mm 87 87

Roughness PPS10 0.86 0.81

ts , ym

Gloss Hunter ts, 48 58

o

0 On the basis of the test, it could be observed that, by the method according to the invention, a paper product of a good quality which had lower basis weight was provided. Then the lighter coated printing paper was provided. In addition, it was discovered that in using wood based component as a pigment and nano- fibrillated cellulose as a strength chemical, similar results were achieved as in using inorganic fill- ers/pigments .

The method according to the present invention is suitable as different embodiments to be used in different paper manufacturing process. The method ac^¬ cording to the present invention is suitable in the manufacture of most different papers. The invention can be applied for use in the manufacture of different paper products in which it is desirable to utilize wood based pigments and strength chemicals. Further, the invention can be applied for use in the manufac^¬ ture of different lighter 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 de^¬ fined by the claims.

Claims

1. A method for manufacturing a paper, wherein

- the paper (10) is formed from a furnish (6) which comprises pulp (1) including at least mechanical pulp (8), a wood based component (2) and a strength chemical (3) ;

- the wood based component (2) and strength chemi- cal (3) are mixed for forming a wood based compo^¬ sition; and

- the furnish (6) is formed from the pulp compris^¬ ing the wood based composition.

2. The method according to claim 1, wherein the strength chemical (3) includes nanofibrillated cellulose .

3. The method according to claim 1 or 2, wherein the pulp (1) includes mechanical pulp (8) be^¬ tween 25 to 100 % by weight of dry weight of the pulp.

4. The method according to any one of claims 1 to 3, wherein the wood based component (2) is a wood based pigment which contains wood fibres and/or fines.

5. The method according to any one of claims 1 to 4, wherein the the wood based component (2) and strength chemical (3) are added into the pulp (1) .

6. The method according to any one of claims 1 to 5, wherein the strength chemical (3) is added into the pulp (1) which contains the wood based component (2) .

7. The method according to any one of claims 1 to 6, wherein the wood based composition is formed on^¬ line from the wood based component (2) and the strength chemical (3) during the treatment of the pulp (1) .

8. The method according to any one of claims 1 to 7, wherein the wood based component (2) and strength chemical (3) has been mixed for forming the wood based composition, and the wood based composition is added into the pulp (1) .

9. The method according to any one of claims 1 to 8, wherein the furnish (6) contains the wood based component (2) between 0.1 to 60 % by weight of dry weight of the pulp.

10. The method according to any one of claims 1 to 9, wherein the furnish (6) contains the strength chemical (3) between 0.1 to 3 % by weight of dry weight of the furnish fibers.

11. A paper, wherein the paper has been formed from a furnish which comprises pulp including at least mechanical pulp, a wood based component and a strength chemical; the wood based component and strength chemi- cal has been mixed for forming a wood based composi^¬ tion; and the furnish has been formed from the pulp comprising the wood based composition.

12. The paper according to claim 11, wherein the paper is coated to form a coated paper.

13. A use of the paper obtained by the method of any one of claims 1 to 10, wherein the paper is used as a printing paper.

14. A furnish, wherein the furnish comprises pulp including at least mechanical pulp and the wood based composition including a wood based component and a strength chemical.

15. A wood based composition, wherein the wood based composition includes a wood based component and a strength chemical.