WO2012025537A1 - Method for producing decorative paper, and paper structure for producing decorative paper - Google Patents

Abstract

In order to reduce the storage cost and production time for decorative papers, according to the invention a paper structure having no filler or little filler is used, which can be adjusted to the requirements of the decorative paper to be produced by applying an individual filler composition. As a result, storage is required only for the paper structure, which can basically be referred to as a "universal paper", and the ingredients of the filler composition, or a filler composition that is already pre-mixed, whereby the storage cost is reduced and the availability of a corresponding starting material for the production process can be quickly assured.

Description

METHOD FOR THE PRODUCTION OF DECORPAPER, AND PAPER SCAFFOLD FOR THE PRODUCTION OF DECORPAPER

The present invention relates to a method for the production of decorative paper according to the preamble of claim 1, as well as a paper framework for the production of decorative paper according to the preamble of claim 12, in particular for use in the inventive method proposed here.

Paper, especially unprinted paper, is made from a liquid pulp. The pulp is dried and processed into unprinted paper. The manufacturing methods used for this purpose are sufficiently known to the person skilled in the art.

Printed decorative paper is essentially produced by printing a unprinted paper delivered to the printer, in particular by the decor manufacturer, in a printing machine having the desired print, in particular decor. The result is correspondingly printed decorative paper.

This printed decorative paper can be used in the wood-based panel industry for coating support materials such as chipboard, MDF boards or the like. For this purpose, printed with a motif papers, especially decorative papers, impregnated with a thermosetting resin such as melamine-formaldehyde resin, urea-melamine-formaldehyde resin or other suitable resin, dried and then pressed under high pressure and high temperature on the material. The materials are further processed into furniture surfaces, laminate floors or similar.

Alternatively, it is also possible to apply so-called plain paper, that is to say non-printed paper, to the support materials using the method outlined above. Then the coloring of the unprinted paper is the decor. The printing is omitted.

Different types of plain paper are needed to produce different types of both plain and printed decorative paper. The types of unprinted paper differ essentially by their composition, in particular with regard to the fibrous materials, sizes or impregnating agents, pigmentation, fillers and auxiliaries. The composition of the unprinted paper, in turn, is essentially predetermined by the composition of the pulp.

This dependency results in some disadvantages. Different types of unprinted papers have to be maintained in order, for example, to be able to react flexibly to the particular need for decorative paper. Alternatively, long delivery times of the decor paper must be accepted if the unprinted paper required for the decorative paper has to be produced and delivered first.

This is where the present invention sets out and makes it its mission to propose an improved process for the production of decor paper, in particular to propose a process which overcomes the disadvantages outlined above.

According to the invention, this object is achieved in that a paper framework without fillers or with only a small proportion of fillers, which is preferably less than or equal to 50% (weight percent) of the final filler is used as unprinted paper and a filler composition is applied to the paper stand. Kaolin or another suitable filler, for example stearin, TiO ₂ , talc, gypsum, barium sulfate, chalk and / or titanium white are suitable as fillers which are already present in the paper stand. The paper stand essentially represents a universally adaptable starting material for the production of decorative paper. The adaptation of the paper stand to the requirements for the decorative paper essentially takes place in that a filler composition is applied to the paper stand, in particular sprayed or printed. This can be done "on the spot" in the printing house, so that the printer can produce almost any decor paper from the paper stand. Accordingly, the printer is not dependent on the delivery times of each required unprinted paper, but can make this from the "universal" paper mill itself. The storage is much easier, since ultimately only the paper framework and the respective fillers must be stored.

Further advantageous embodiments of the proposed invention will become apparent in particular from the features of the dependent claims. The features of the various claims can be combined as desired.

To produce a printed decor paper can advantageously be provided that the produced according to the inventive method unprinted decorative paper is printed. This is preferably done after applying the filler composition.

It is advantageously provided that the paper stand comprises fibers, adhesives or impregnating agents and / or auxiliaries. Otherwise, the paper stand is preferably free of filler or filler. Examples of fibrous materials include groundwood, semichemicals, pulps and other fibers. As adhesives or impregnating agents, in particular resins, paraffins and / or waxes are used. As auxiliaries, for example, water, dyes, defoamers, dispersants, retention aids, flocculants, wetting agents and / or wet strength agents are used.

Kaolin, stearin, TiO ₂ , talc, gypsum, barium sulfate, chalk and / or titanium white are suitable as fillers used in the filler composition. An increase in opacity can be achieved, for example, by adding TiO ₂ to the filler composition. This leads to a higher concentration of TiO ₂ in the upper areas of the decorative paper. The higher surface concentration of the TiO ₂ leads to better light absorption and thus to a higher opacity, than with a distribution of the same amount of TiO ₂ in the entire decorative paper. A decorative paper of equal opacity can thus be produced with less TiO ₂ .

It can also be advantageously provided that the filler composition, in addition to a filler or fillers, contains an anionic, polycarbonate-containing aliphatic polyurethane dispersion. A resulting advantage is, for example, the saving of impregnating resins. If, as proposed here, an aliphatic, polycarbonate-containing anionic polyurethane dispersion is a constituent of the filler composition, the amount of melamine-formaldehyde resins or urea-melamine-formaldehyde resin mixtures or similar resins necessary for the impregnation can be correspondingly reduced.

It may also be advantageously provided that the filler composition, in addition to a filler or fillers, contains an acrylate dispersion. The acrylate dispersion is an alternative binder to the anionic polycarbonate-containing aliphatic polyurethane dispersion in the applied filler. It thus essentially ensures that the liability is ensured.

It has also been found that specifically using an anionic, polycarbonate-containing aliphatic polyurethane dispersion as constituent of the filler composition, the TiO _{2 is} better fixed on the surface of the decorative paper. Inadequate fixation of TiO ₂ leads to loss of quality due to contamination of the impregnating resins during further processing, especially during impregnation of decorative papers. This occurs preferentially at high TiO ₂ concentrations in the decorative papers, since then the TiO ₂ concentration competes with the binder concentration.

By fixing the paper stand with an anionic, polycarbonate-containing aliphatic polyurethane dispersion further reduces the growth of the decorative paper to absorb a liquid such as water or impregnating resin. In particular, in the production of floor laminates, the growth of the decorative paper must be very carefully controlled so that the width of individual panels matches the width of the printed decoration of the panels. A better fixation of the paper frame leads to a better predictability of the growth of the decorative paper and thus to less rejects.

It has also been found that a paper stand which has been treated with a filler composition which additionally contains an anionic, polycarbonate-containing aliphatic polyurethane dispersion, after further processing is more elastic than a decorative paper with another binder. This is particularly evident in outdoor applications, where varying temperature and humidity stresses can cause cracking in the surface of the processed material. The tendency for cracking is significantly reduced when the binding of the fillers using an anionic, polycarbonate-containing aliphatic polyurethane dispersion is ensured in the paper stand.

For example, when fillers are bonded to the paper stand using an anionic polycarbonate-containing aliphatic polyurethane dispersion in the filler composition, the phototrophy, i. H. the reversible change of a color after irradiation with light, reduced, that is, increased light fastness. In the current state of the art decorative papers must be printed with lightfast pigments so that the decorative papers are covered as completely as possible. This results in limitations in the selection of the decor and it must be a large amount of expensive paint applied with pigments with high light fastness.

In a further advantageous development of the proposed invention it can be provided that the filler composition contains pigments, such as FeO, organic pigments or metallic effect pigments, such as, for example, mother of pearl. Thus, with suitable pigment mixture, all paper dyeings can be produced from the paper stand. A storage of different paper dyeings is no longer necessary.

In a further advantageous embodiment of the proposed invention can be provided that the filler composition contains additives such as silica. The use of silica increases the scratch resistance of decorative paper after it has been applied to a wood-based material carrier.

It can be advantageously provided that 3 - 15 g / qm filler composition is applied to the paper stand. Thus, the opacity of the decorative paper can be adjusted specifically. The opacity of decorative papers is usually higher than would be necessary for the printed decor, since it must be assumed in the production of decorative papers that the case may occur that only a small amount of opaque ink is printed on the decorative papers. Nevertheless, the opacity must then still be high enough to cover a lying under the decorative papers wood material carrier. Since the printer knows how opaque the ink printed on the decorative papers is, the opacity of the decorative paper can be adjusted by the printer. This results in cost advantages.

In a further advantageous embodiment of the proposed method can be provided that the filler composition at least on the top, i. the possibly to be printed or visible on the wood material side, preferably also applied to the underside of the paper stand. A lateral uprighting of the paper edges, the so-called bowls or curling, is minimized by a more symmetrical structure. The paper is easier to process.

Another object of the present invention is to propose a paper scaffold for the production of decorative paper.

This object is achieved by a paper scaffold with the characterizing features of claim 12. Because a paper stand is free of fillers or contains a small amount of fillers, such as kaolin, stearin, TiO ₂ , silica, talc, gypsum, barium sulfate, chalk and / or titanium white, this paper framework can be tailored to the needs of the produced Decor paper to be customized. The storage costs are reduced because basically only this "universal paper" has to be stored.

The subclaims relate to preferred developments of the paper mill according to the invention.

Particularly preferably, it is provided that the amount of filler in the paper stand is at most 50 percent by weight of the amount of filler which is to be contained in the decorative paper to be produced. Such a paper framework is still sufficiently universal to be adapted to the needs of the decorative paper to be produced. Similarly, a minimum amount of filler is included, which ensures a certain stability of the paper stand.

Further features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. Show in it

Fig. 1 is a schematic representation of the method according to the invention;

2 shows a paper stand according to the method of the invention;

3 shows an unprinted decorative paper (plain paper) produced according to the method of the invention;

4 shows a printed decorative paper produced according to the method of the invention.

The following reference numerals are used in the figures:
1 paper framework
2 filler composition
3 print layer / color

The method according to the invention will be described in more detail below, also taking into account upstream and downstream process steps. The description is made schematically, so that no closer to the person skilled in any known or familiar process details or method intermediate steps is received.

A method according to the invention for producing decor paper comprises at least the application of a filler composition 2 to a filler-less or low-filler paper stand 1. The result of this method step is a plain decorative paper (plain paper). In a subsequent process step, printing of the unprinted decorative paper can take place. The result of this method step is accordingly a printed decor paper with a print layer 3.

The method steps outlined above precede the actual production of the paper stand, which is carried out essentially at a paper manufacturer. For a better understanding of the invention will be discussed here also briefly on the upstream production process of the paper mill.

• Faserstoffe, beispielsweise Holzschliff, Halbzellstoffe, Zellstoffe, andere Fasern ggf. auch
• Leim- und Imprägnierstoffe, insbesondere Harze, Paraffine, Wachse und/oder
• Hilfsstoffe, insbesondere Wasser, Farbstoffe, Entschäumer, Dispergiermittel, Retentionsmittel, Flockungsmittel, Netzmittel, Nassfestmittel

It is first prepared a liquid pulp, but does not contain fillers such as kaolin, stearin, TiO ₂ , talc, gypsum, barium sulfate, chalk and / or titanium white. The pulp, however, should be particular

• Fibers, such as groundwood, semi-pulps, pulps, other fibers possibly also
• Glues and impregnating substances, in particular resins, paraffins, waxes and / or
• Auxiliaries, in particular water, dyes, defoamers, dispersants, retention aids, flocculants, wetting agents, wet strength agents

contain.

Alternatively, the pulp, in addition to the above-mentioned substances, a small amount of filler, such as kaolin, stearin, TiO ₂ , talc, gypsum, barium sulfate, chalk and / or titanium white have.

The fillerless or low-filler pulp is further processed in a manner known per se in a paper machine to form a two-dimensional paper stand 1.

• Faserstoffe, beispielsweise Holzschliff, Halbzellstoffe, Zellstoffe, andere Fasern ggf. auch
• Leim- und Imprägnierstoffe, insbesondere Harze, Paraffine, Wachse und/oder
• Hilfsstoffe, insbesondere Wasser, Farbstoffe, Entschäumer, Dispergiermittel, Retentionsmittel, Flockungsmittel, Netzmittel, Nassfestmittel

The paper framework should therefore essentially also

• Fibers, such as groundwood, semi-pulps, pulps, other fibers possibly also
• Glues and impregnating substances, in particular resins, paraffins, waxes and / or
• Auxiliaries, in particular water, dyes, defoamers, dispersants, retention aids, flocculants, wetting agents, wet strength agents

contain.

However, the paper stand 1 can be free of fillers. Alternatively, the paper stand 1 with only a small proportion of fillers, such as kaolin, stearin, TiO ₂ , silica, talc, gypsum, barium sulfate, chalk and / or titanium white equipped. The amount of filler in the paper stand before applying the filler composition should be at most 50% by weight of the amount of filler to be contained in the decorative paper to be produced (final amount of filler). A certain proportion of fillers may advantageously be present as an adhesive in the paper stand. The fillers used there such as kaolin are inexpensive and only slightly opaque. The paper framework as such is also not very opaque.

The paper stand 1 is present for example as a paper strip, which is rolled up on a roll. Of course, other shapes are conceivable, such as individual sheets in rectangular or square formats.

The paper scaffolding is usually produced in a paper mill. The paper scaffolding is usually delivered to a print shop for further processing. Such a paper framework is shown schematically in FIG.

The filler-free or low-filler paper framework is first fed to a coating plant in the printing house. In the coating system, a filler composition 2, in particular in liquid form, is applied to the paper stand. About 3 to 15 gsm of filler composition is applied. The amount of applied filler composition sets the opacity of the unprinted or printed decor paper. If appropriate, the filler composition on the upper side is also applied on the lower side of the paper stand. This usually results in a high concentration of fillers in this position. A particular focus of the invention is, in particular, to concentrate the opaque fillers only on the surface.

The filler composition 2 contains - in addition to water or other solvents - fillers such as kaolin, stearin, TiO ₂ , talc, gypsum, barium sulfate, chalk and / or titanium white.

The filler composition 2 may additionally contain additives such as silica.

The filler composition 2 may further contain, as a binder, an anionic, polycarbonate-containing aliphatic polyurethane dispersion. Such a dispersion has become known, for example, under the brand name Bayhydrol from Bayer (Bayhydrol is a registered trademark of Bayer). Acrylate dispersions or casein dispersions can also be incorporated into the filler composition as binders.

The filler composition 2 may additionally contain pigments such as FeO, organic pigments, metallic effect pigments e.g. Mother-of-pearl and additives included.

The result of this coating process is an unprinted decorative paper. This unprinted decorative paper may already be used as so-called plain paper, i. Decorative paper which optionally only has a coloring, are applied to a support material. It has been found that an unprinted decorative paper produced in this way has high opacity without having to be printed in a further process step. The advantage over currently used plain papers lies in the fact that the grammage is lower with the same opacity. This results in cost advantages, since plain papers can be used with a lower basis weight. Such a blank decorative paper is shown schematically in FIG. In principle, the applied filler dispersion penetrates into the paper framework to a certain but negligible degree. In this respect, FIG. 3 is predominantly schematic.

Alternatively, the unprinted decorative paper can be printed in an additional process step. Rotogravure printing, flexographic printing, digital printing or any other suitable printing process come into question here. The result is a printed decor paper, which can also be applied to a substrate. The processes known for this purpose are sufficiently known to the person skilled in the art, so that no further explanation is necessary at this point. A printed decorative paper is shown schematically in FIG. 4.

The method according to the invention basically assumes that the paper stand 1 is produced by a paper manufacturer and coated in the printing shop with the desired filler composition 2. However, it is also conceivable that the paper stand is stored at the paper manufacturer and is already coated at the paper manufacturer according to the requirements of the printing company with the filler composition. Here, too, there are advantages for the entire production process of the decorative paper, since in this case too the storage costs decrease and the production time for the desired decorative paper can drop significantly.

It should also be noted that the proposed method does not describe the so-called "coating" of paper, for example by glues, etc., which is used, for example, for surface smoothing of the paper.

Claims (14)

1. Process for the production of decorative paper from unprinted paper, characterized in that

   - When unprinted paper a paper framework (1) is used without fillers or with only a small proportion of filler,

   - A filler composition (2) is applied to the paper stand (1) to produce a plain decorative paper.
2. A method according to claim 1, characterized in that the unprinted decorative paper is printed to produce a printed decorative paper.
3. Method according to at least one of the preceding claims, characterized in that the paper stand (1) contains fibers, adhesives or impregnating agents and / or auxiliaries.
4. Method according to at least one of the preceding claims, characterized in that the filler composition (2) contains at least one filler such as kaolin, stearin, TiO ₂ , talc, gypsum, barium sulfate, chalk and / or titanium white.
5. Method according to at least one of the preceding claims, characterized in that the amount of filler in the paper stand (1) prior to application of the filler composition (2) is at most 50 percent by weight of the amount of filler to be contained in the decorative paper to be produced.
6. Method according to at least one of the preceding claims, characterized in that the filler composition (2) contains an anionic, polycarbonate-containing aliphatic polyurethane dispersion.
7. Method according to at least one of the preceding claims, characterized in that the filler composition (2) contains an acrylate dispersion.
8. Method according to at least one of the preceding claims, characterized in that the filler composition (2) pigments, such as FeO, organic pigments and / or metallic effect pigments, such as mother of pearl, contains.
9. Method according to at least one of the preceding claims, characterized in that the filler composition (2) contains additives, such as, for example, silica.
10. Method according to at least one of the preceding claims, characterized in that 3-15 g / m² of filler composition (2) is applied to the paper stand (1).
11. Method according to at least one of the preceding claims, characterized in that the filler composition (2) is applied at least on the top, preferably also on the underside of the paper stand (1).
12. Paper stand for the production of decorative paper, in particular for use in a method according to at least one of claims 1 to 11, characterized in that the paper stand (1) is free of fillers or a small amount of fillers, such as kaolin, stearin, TiO ₂ , Silica, talc, gypsum, barium sulfate, chalk and / or titanium white.
13. Paper stand according to claim 12, characterized in that the amount of filler in the paper stand (1) is at most 50 percent by weight of the amount of filler which is to be contained in the decorative paper to be produced.
14. Paper scaffolding according to at least one of the preceding claims, characterized in that the paper scaffold (1) fibers, in particular groundwood, semichemicals, pulps and / or adhesives or impregnating agents, in particular resins, paraffins, waxes and / or auxiliaries, in particular water, dyes, Defoamer, dispersant, retention agent, flocculant, wetting agent, wet strength agent contains.

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