EP0754260B1 - Web printing paper coated on both sides and process for its manufacture - Google Patents

Abstract

PCT No. PCT/EP95/01283 Sec. 371 Date Sep. 30, 1996 Sec. 102(e) Date Sep. 30, 1996 PCT Filed Apr. 7, 1995 PCT Pub. No. WO95/27824 PCT Pub. Date Oct. 19, 1995A web printing paper, including a coating base paper which contains mineral filler and at least one of wood pulp and cellulose as fiber components. The coating base paper has a grammage of 30 to <58 g/m2, and a filler content, relative to its grammage, equal to 15 to 35% by weight. The coating base paper selectively contains, in addition to the at least one of wood pulp and cellulose, up to <50% by weight recycled fibers, all weight parts adding up to 100% by weight. The printing paper further includes a coating applied to both sides of the base paper by a film press so as to absorb printing ink. The coating contains pigment and binder. The coating on each side of the base paper has a grammage of 2 to 12 g/m2, and the pigment of the coating has a grain size, 40 to 60% by weight, of <2 mu m.

Description

The present invention relates to a bilateral coated web printing paper, consisting of a coating base paper, the mineral Filler and wood fiber as fiber components and / or contains pulp, which is for inclusion printing ink, pigment and binder containing stroke by means of a film press is applied. The invention further relates to a Process for the production of roll printing paper.

Roll paper of the type specified at the beginning are used for the production of Magazines, especially illustrated ones Magazines, magazines, catalogs and Advertising brochures, as they usually do Daily newspapers or illustrated magazines are attached.

There have been numerous attempts to lower it the manufacturing cost of the papers in question undertaken, in particular by lowering the Basis weight of the to be used Coating base papers or by exchanging the used cellulose and / or wood pulp fibers against recycled fibers.

An overview of offset papers containing wood, as are common in Europe, can be found in the article: "Study on binder systems for LLWC and MFP papers", published in "Wochenblatt für Papierfabrikation" 9 (1988), pages 337 to 344 This study also describes a film press used to apply preparations for the paper types in question. The pigment composition described consisted of a mixture of 60 parts of English China Clay and 40 parts of a fine American kaolin. To summarize, the authors of this literature come to the conclusion that when using an SD coater (short residence coating device) 20 parts by weight of binder are required for an application of 5 g / m ² or 30 parts for a 3 g / m ² application are. However, if a film press is used instead of an SD coater, an increase in the binder level is considered necessary in order to achieve the same printing gloss, but with reduced opacity.

In "Wochenblatt für Papierfabrikation" 16 (1990), pages 701 to 708 and the equivalent reference "Pulp and Paper Canada" 92: 4 (1991), pages 52 to 58, the surface treatment of newsprint using a film press is reported. A raw paper with only an ash content of 0.4% by weight was used in these investigations. There is no information on the fineness of the pigments used for the surface treatment. In the formulations used for surface pigmentation, the extraordinarily high binder content of 70% by weight, based on pigment, is striking. The investigations are essentially limited to a coat weight of 5 g / m ² and page.

EP-A-0 377 983 A2 relates to a newsprint paper coated by means of an air brush or a roller coater, which is said to have improved ink acceptance, surface strength and opacity. Line weights of between 1 and 12 g / m ² , preferably between 3 and 8 g / m ² and the side to be printed are disclosed, a total area weight of 60 g / m ² not to be exceeded. The filler content of the known coating base paper is in the usual range between 0.5 and 10% by weight, but preferably less than 0.5% by weight.

In "Wochenblatt für Papierfabrikation" 1 (1988), pages 1 to 6, the article "Surface-coated SC papers, a challenge for LWC papers" relates to the coating of SC papers with a filler content of 15 to 25%. The SDTA application system (short dwell time applicator) is specified as the application device. The application weights are in the range of up to 3.5 g / m ² and page, while in the case of coating base papers with a lower filler content of less than 10% by weight, higher application weights are required, such as. B. in the so-called LWC papers, up to a coat weight of about 9 g / m ^{2 '} and page.

According to the essay: "Possibilities for on-line coating of filled, wood-containing papers, published in" Wochenblatt für Papierfabrikation "13 (1992), pages 507 to 515, highly filled, improved SC papers are first made available by means of a film press with a pigmentation of calcium carbonate and at least 30% by weight of binder, based on the pigment, pretreated so that the papers have sufficient strength to be able to apply the actual top coat in a second operation by means of a knife coater Kaolin and fine calcium carbonate, with 12 parts by weight of binder per 100 parts by weight of pigment mixture.The minimum application quantity for the top coat is 7 g / m ² and side, for example application weights of up to 19 g / m ² , while for the primer 4 to 5 g / m ^2. Specified, although the paper produced, the novel stri Representing paper quality, some of which have excellent properties, there are disadvantages insofar as the required double-coat application and the high coat weight result in paper which, due to the costs involved, must remain closed to essential areas of application. The disadvantages of film splitting at the exit of a film press are shown in detail in this article.

In the article: "Surface treatment of AP-containing printing papers - a challenge on the way to new paper qualities", published in "Wochenblatt für Papierfabrikation" 2 (1993), pages 53 to 61, is about various coating devices, including the under The name "speedsizer" became known film press reports. With regard to the surface treatment of SC paper, a pigment layer of 4 to 5 g / m ^{2 is} considered sufficient for achieving a good gravure printing quality, although it is found restrictively that a higher coating weight improves the coverage and whiteness when using a speedsizer pronounced film splitting results and a drastic drop in smoothness results. A second coating step with a doctor blade coating device is therefore deemed expedient for achieving good gravure printing properties, which, admittedly, has to result in high machine expenditure and additional operating costs and thus an increase in the price of the product.

Finally in the essay: "Operating experience with Twin HSM at Surface finishing of base papers Waste paper base ", published in" Wochenblatt für Papierfabrikation "21 (1993), pages 886 to 890, about the problems when using a film press reported and also high order weights mentioned, but on the type of applied Coating colors only reveals that it is were pigmented compositions.

The present invention has the task of a roll paper coated on both sides for To provide that under cost effective Conditions can be produced at the Not making a double stroke in particular is necessary, the fibrous material may be from There is recycled fiber and its appearance and Printability with the usual ones Web printing paper is comparable. Especially the invention wants a gravure capable Provide roll printing paper.

• das Streichrohpapier eine Flächenmasse von 30 bis < 58 g/m² aufweist,
• der Füllstoffgehalt des Streichrohpapiers - bezogen auf seine Flächenmasse - 15 bis 35 Gew.% beträgt,
• das Streichrohpapier außer Holzstoff und/oder Zellstoff wahlweise bis zu < 50 Gew.% Recyclingfasern enthält, wobei sich alle Gewichtsteile auf 100 Gew.% ergänzen,
• der Strich je Seite eine Flächenmasse von 2 bis 12 g/m² aufweist,
• das Pigment des Striches zu 40 bis 60 Gew.% eine Korngröße < 2 µm aufweist und
• das Pigment des Striches eine mittlere Korngröße im Bereich von 1,3 bis 2,5 µm aufweist.

To achieve the object, the invention provides a roll paper coated on both sides, which consists of a coating base paper, which contains mineral filler and, as fiber components, wood pulp and / or cellulose, the line used to hold the printing ink containing pigment and binder and being applied by means of a film press , the paper being characterized in that

• the coating base paper has a basis weight of 30 to <58 g / m ² ,
• the filler content of the coating base paper - based on its mass per unit area - is 15 to 35% by weight,
• the coating base paper optionally contains up to <50% by weight of recycled fibers in addition to wood pulp and / or cellulose, all parts by weight adding up to 100% by weight,
• the line has a mass per unit area of 2 to 12 g / m ² ,
• the pigment of the coating has 40 to 60% by weight of a grain size <2 µm and
• the pigment of the coating has an average grain size in the range from 1.3 to 2.5 μm.

Before taking advantage of the present invention, their other preferred embodiments and the process of making the roll printing paper according to the invention closer are explained in the description and Terms used in patent claims are explained:

Among the roll printing papers according to the invention are only single-ply papers for Difference of z. B. to understand cardboard.

The mineral pigments are included under filler understand the fiber suspension at the Papermaking can be added. It will be there no distinction between freshly added Fillers and fillers, which together with fiber materials recovered from waste paper Papermaking process are fed.

Recycled fibers are recovered from waste paper Fibers, according to the invention in particular those from the waste paper type are preferred D31 according to the list of German Standard varieties can be obtained.

Deinkt recycled fibers are fibers of which the Ink is largely removed.

Under wood pulp are mechanically crushed To understand wood fibers, both so-called cut types as well as those with the help varieties obtained from refiners. A lineup of the different types of wood is in the Literature: "Zellstoff und Papier" 37 (1988), Page 212. Of these listed there According to the invention, types of wood are particularly the so-called TMP substance (thermo-mechanical Refiner wood pulp) preferred.

Under pulp or pulp are "fresh" To understand fibers, in contrast to the Recycled fibers on wood pulp or Pulp base.

The term film press becomes here Labeling of all facilities used at which are pre-dosed with the coating color Metering rollers, doctor blades and smooth or grooved squeegee on a transfer roller takes place, of which "indirectly" the predosed Coating color to form the coating the coating base paper web is transmitted. Closer Explanations are included in the one discussed above Literature: "Wochenblatt für Papierfabrikation "13 (1992), pages 507 to 515; furthermore the reference: "Wochenblatt für Papierfabrikation "6 (1992), pages 193 to 197.

Hot-soft calenders are also known in the professional world Soft Compact Calendar called, the Nip from a heated chilled cast iron and a related roller with elastic plastic, see p. a. "Weekly paper for paper manufacture "16 (1990), pages 701 to 708.

All weight information on fiber materials, Coating base papers and coated papers or Coatings refer to "oven dry" Weight information. Binder information concerns the solids content of the binder.

Used to determine the grain size of the pigment one of the known sedimentation processes, e.g. B. Andreas pipette, sedigraph or Shimadzu centrifuge.

To ensure a uniform coat surface, it has proven to be expedient for the coating pigments to have an average grain size in the range from 1.3 to 2.5 μm and for their BET surface area to be between 6.5 and 9 m ² / g.

It is preferably in accordance with the Invention pigments present in the line exclusively mineral pigments. As a result their relatively coarse grain distribution became such Pigments used to fill the pulp added in papermaking. The inventors had now recognized that when using this coarse-grain pigments as coating pigments for a to be applied by means of a film press Coating color does not the so-called film splitting or at least in a much smaller one Extent occurs and therefore an essential smoother line surface is created. The invention therefore also possible with highly pigmented Coating inks a problem-free job too much higher coat weights. With a single line is good coverage of the Coating base surface possible. From measures known in the art, such as the Apply a primer using a film press and the subsequent order one to include the Ink serving lines using a Doctor blade coating device can therefore be omitted. The pigment of the coating preferably has 40 up to 55% by weight of a grain size <2 µm. Possibly. can the line pigment up to max. 10% by weight - related on total pigment content - one or more non-mineral pigments such as B. unresolved Starch granules included.

In connection with the high filler content of the coating base paper from 15 to 35% by weight, especially with line application weights of more than 5 g / m ² and page, a roll printing paper of high opacity and good surface structure is produced, which can be printed in both offset and gravure printing. It is preferred that the pigment content of the coating is not less than 80% by weight, based on the total solids content of the coating, with conventional coating color auxiliaries in a minor amount of max. 1.5% by weight can be present. The use of a film press as a coating device not only enables the coating base paper to be reduced to 30 g / m ² , it also makes it possible, in conjunction with the pigment composition according to the invention, for the coating used to hold the printing ink, apart from wood pulp and / or cellulose <50% by weight of the base paper from recycled fibers, preferably from deinked recycled fibers.

In economic terms, the present invention once the advantage of access to the compared to the usual finely divided coating pigments cheaper Coating pigments according to the invention Saving material costs, furthermore arises the advantage with just a single swipe reduce manufacturing costs and finally, the invention also offers the advantage in considerable ways on recycled fibers to be able to fall back on. The invention is not limited to the use of recycled fibers, rather, considerable ones are already emerging economic benefits from the reduced Material and manufacturing costs, even if the pulp of the coating base paper from only There is wood pulp and cellulose.

Are preferably as Coating pigments kaolin, calcium carbonate and talc suitable. According to another preferred Embodiment is the invention coating pigment to be used to more than 80% by weight from kaolin, calcium carbonate, talc or one Mixture of these coating pigments in the specified Grain size distribution, while the rest of the Coating pigment from pigments of the same type, however in finer distribution or from other pigments, such as B. made of aluminum hydroxide, bentonite or Titanium dioxide can exist.

To achieve particularly good coverage of the coating base paper, a coat application of more than 5 g / m ² and page is preferred, but the application weight should not exceed 10 g / m ² and page.

The level of binder in the coating is determined according to the intended use of the invention Web printing paper, with one for dry offset roll paper to be printed Binder content of 12 to 20% by weight, based on Pigment, is preferred while for the Wet offset printing has a binder content of 10 to 15 % By weight is sufficient. For a gravure printing too printing roll printing paper is according to the invention a binder content of 4 to 7 wt.% Based on pigment.

The usual binders in particular come Synthetic latices on acrylate and Butadiene styrene base in question, further - especially with offset printing recipes - Starch-based binders, generally it is preferred that the binder as a whole consists predominantly of a synthetic latex. Only with offset printing recipes with Binder proportions of more than 10% by weight can also more than 50% by weight, but not more than 65 % By weight from a starch-based binder consist.

For the production of the invention Roll printing paper has become a coating base paper proven to be particularly suitable for Improvement in strength during manufacture cationic starch added as a mass additive has been. The fillers of the coating base paper preferably consist mainly of kaolin, Calcium carbonate and talc or a mixture of these substances.

The production of the roll printing paper can done online according to the invention, d. H. the Coating base paper becomes directly after it dries the film press to apply the coating fed and possibly also without intermediate winding Application and drying of the coating directly smoothed using a calender. As a calender come here a super calender or a hot-soft calender in question.

The following examples explain the Invention:

In Examples 1 and 2 below, a wood-based coating base paper with a basis weight of 52 g / m ² and a filler content of 31% by weight was coated in an experimental coating device equipped with a film press - application weight: 6 g / m ² and side - and dried a super calender satin. Coating color 1 (example 1): kaolin 45% by weight <2 µm 100 parts by weight self-thickening acrylic latex 5 parts by weight Na stearate 0.5 parts by weight Solids content 40% by weight Coating color 2 (example 2): Kaolin as in coating color 1 60 parts by weight talc 44% by weight <2 µm 40 parts by weight other components and solids content as in coating color 1.

A visual assessment of the gravure printed web showed excellent Printing result.

Claims (10)

1. Web printing paper coated on both sides, comprising a coating base paper containing mineral filler and, as fibrous components, wood pulp and/or cellulose, the pigment- and binder-containing coating, which serves to receive the printing ink, being applied by means of a film press, characterised in that

   the coating base paper has a mass per unit area of from 30 to < 58 g/m²,

   the filler content of the coating base paper, based on its mass per unit area, is from 15 to 35 % by weight,

   the coating base paper optionally contains, besides wood pulp and/or cellulose, up to < 50 % by weight recycled fibres, the sum of all the weight components being 100 % by weight,

   the coating on each side has a mass per unit area of from 2 to 12 g/m²,

   from 40 to 60 % by weight of the pigment of the coating has a particle size of < 2 µm, and

   the pigment of the coating has a mean particle size in the range from 1.3 to 2.5 µm.
2. Web printing paper coated on both sides according to claim 1, characterised in that from 40 to 55 % by weight of the pigment of the coating has a particle size of < 2 µm.
3. Web printing paper coated on both sides according to either claim 1 or claim 2, characterised in that the pigment of the coating consists predominantly of kaolin, calcium carbonate, talcum or a mixture of those pigments.
4. Web printing paper coated on both sides according to any one of claims 1 to 3, characterised in that more than 80 % by weight of the pigment of the coating consists of kaolin, calcium carbonate, talcum or a mixture of those pigments.
5. Web printing paper according to any one of claims 1 to 4, characterised in that the coating on each side has a mass per unit area of > 5 g/m².
6. Web printing paper coated on both sides according to any one of claims 1 to 5, characterised in that the coating has a mass per unit area of not more than 10 g/m² on each side.
7. Web printing paper coated on both sides according to any one of claims 1 to 6, characterised in that the coating contains, based on the pigment of the coating, from 12 to 20 % by weight binder.
8. Web printing paper coated on both sides according to any one of claims 1 to 7, characterised in that the coating contains, based on the pigment of the coating, from 10 to 15 % by weight binder.
9. Web printing paper coated on both sides according to any one of claims 1 to 7, characterised in that the coating contains, based on the pigment of the coating, from 4 to 7 % by weight binder.
10. Process for the preparation of a web printing paper coated on both sides according to any one of claims 1 to 9, characterised in that

    on a coating base paper having a mass per unit area of from 30 to < 58 g/m² and a mineral filler content of from 15 to 35 % by weight, the coating base paper optionally containing, besides wood pulp and/or cellulose, up to < 50 % by weight recycled fibres, the sum of all the weight components being 100 % by weight,

    a coating liquid is applied to each side of the coating base paper by means of a film press in order to achieve a weight of applied coating having a mass per unit area of from 2 to 12 g/m² on each side, the applied coating liquid is dried and the dried paper is glazed by means of a calender, with

    from 40 to 60 % by weight of the pigment of the coating having a particle size of < 2 µm, and

    the pigment of the coating having a mean particle size in the range from 1.3 to 2.5 µm.