DK145723B - PROCEDURE FOR THE PREPARATION OF A FILM FOR USING A DECORATIVE COATING MATERIAL FOR A SUBSTRATE - Google Patents

Description

145723

The present invention relates to a process for preparing a foil for use as a decorative coating material for a substrate, wherein a process impregnated with a hardenable resin-resinous paper web is coated with a mixture of pigment and binder, and optionally also a dye. which method is characterized by using a paper web made by impregnating a cellulosic fibrous sheet material in a papermaking machine prior to final drying with the curable resin resin used in an amount of 5-60% by weight solids , based on the weight of the impregnated paper web, the preparation being carried out in such a way that a paper web of Gurley of at least 12 seconds / 100 ml is reported.

The fabricated film can be applied to substrates, for example "particle boards" (chipboard, crumb or fiberboard), furniture boards, plywood sheets, fillings and the like.

Due to the need for rationalization in the furniture industry, there is a great need for surfaces that do not need paint. This need has so far been largely met by the use of melaminim embossed printed and unprinted paper materials which are pressed on, for example, 20 particle board, crumb or fiberboard or furniture parts under elevated temperature and pressure. These surfaces cannot, from an aesthetic point of view, be compared to a surface painted in the usual way.

From German publication no. 1,546,451 and Norwegian patent no.

101.120, on the one hand, it is known to impregnate finished resin paper in accordance with the German disclosure, and on the other hand it is known to impregnate paper by adding to the pulp a resin in accordance with the Norwegian patent specification. described technique. However, the method according to the invention, which can be said to consist of impregnation in the middle of the extremes stated, yields significant advantages.

In the prior art impregnation with the addition of resin to the pulp as described in the Norwegian patent, there are, of course, obvious difficulties in imparting the resin produced later to such a content that the desired impregnation is obtained.

The method is thus uneconomical, and the practical experience shows that already recording as low as approx. 5% by weight causes great difficulties and can only be achieved by adding a very large 5 excess amount to the pulp. The Norwegian patent further discloses a technique which also differs in other respects from the impregnation method of the present invention, in that, according to the Norwegian patent, impregnating monomer is added to a polymer, which further accentuates the absorption problem. Namely, the uptake of monomer is significantly lower than the uptake of polymer since the monomer has a lower weight per unit weight. charging unit. The pulp is anionic, ie. negatively charged while the resin is cationic, i.e. positively charged, making uptake of polymer or finished resin significantly more efficient.

15 The process according to the German disclosure document, which consists in impregnating the final dried paper, entails disadvantages as discussed further below.

By performing the impregnation in a papermaking machine prior to final drying, it is possible to produce a dense paper with a sufficient resin content suitable for subsequent coating. The addition of the resin can be carried out differently depending on the final product and technical equipment requirements, and the resin solids content can also be varied in a similar manner within as wide limits as 5-60% by weight based on the weight of the impregnated paper web . A particularly preferred range of resin solids content is 15-40% by weight, calculated on the same basis.

In the process of the invention, the impregnated paper is given a porosity of at least 12 seconds / 100 ml after Gurley. The paper 30 is finally coated by applying a mixture of pigment and binder and optionally also a dye. The impregnating agent used is preferably an aqueous resin solution or dispersion.

3 145723

The reason why this method is advantageous lies in the fact that the cellulose fibers undergo irreversible changes in drying in the papermaking machine in a manner known per se. In order to enable subsequent impregnation, it is usually necessary to make the paper very open, i.e. it must be avoided that the fibers are processed too much in the Dutch, so that the paper has a pore system which facilitates impregnation. However, this openness still persists after the impregnation and creates difficulties for the subsequent coating. It is desirable to retain the paste of the applied coating on the surface, but the openness or porosity of the paper causes it to penetrate instead.

If the impregnation with the impregnating agent, for example of the urea or melamine resin type, according to the invention is carried out in connection with the papermaking prior to the final drying, either by applying it to the paper or by applying it to the paper machine by spraying, in a glue press or a bath or combination thereof, the dilemma stated above can be avoided.

As long as the paper is not finally dried, it still has its porous structure and can be easily impregnated, even at higher degrees of machining in the Dutchman, whereby, after final drying, a denser paper is obtained. In this case, the paper may also be provided with a machine-worn surface which further improves the result of the subsequent coating.

The subsequent surface coating can be carried out in a manner known per se. If an aqueous dispersion is used, it is preferable to use an aerosol sprayer or scraper, whereas the use of solvents or other volatile components using the best results is achieved by the use of roller coating or coating in a so-called carpet coating machine.

In principle, any type of thermoplastic or thermosetting resin resin compatible with or dispersible in water can be used in the process of the invention. As a particularly suitable resin type, mention may be made of the aminoplastic type, for example urea or melamine resins. Furthermore, it is possible to use thermosetting plastics of the pheno, acrylic, epoxy, polyurethane and polyester plastics materials.

The mixture of pigment and binder used for the final coating may have a very varied composition in accordance with conventional techniques. Thus, as pigment, titanium dioxide, clay or lime can be used. The binder in the coating composition may be, for example, acrylic latex, styrene-butadiene latex, melamine resin or urea resin or contain a UV curing or catalyst curing polyester or a nitrocellulose or acid curing type binder. The coating mixture may also contain a dye, if desired.

The cellulose-based fibrous material constituting the paper web may be derived from any cellulose source, e.g., mechanical pulp, chemical pulp and semi-chemical pulp. Chemical pulp comprises sulfite and sulfate pulp which can be used in bleached, semi-bleached or unbleached form, with preferred bleached pulp, and especially bleached sulfate pulp.

The invention is further illustrated by the following examples. In these examples, the porosity is given by Gurley and the porosity value is determined by the standard method SCAN-P 19:66. In all Examples 20 there are. referred to the use of bleached sulfate cellulose, but all kinds of cellulose-based fibrous materials can be used to form the paper web, for example, as stated above.

EXAMPLE 1 2

Paper weighing approx. 60 g / m is prepared from bleached sulphate cellulose while adding approx. 10% by weight of urea resin (based on the dry paper weight) in the pulp and approx. 20% by weight when spraying onto the paper web after the pressing section. The urea resin added to the pulp is a resin of the trade name Dynorit® L 320 (Dyno Industrier, Norway) and the resin applied to the paper web by spraying is Kaurit 210® together with 0.02% by weight ammonium chloride as catalyst. The impregnated paper 2 has a surface weight of approx. 80 g / m and a porosity of 80 seconds / 100 ml according to Gurley. In a subsequent process, the paper is coated with 40 g / m 2 of a pigmented polyester lacquer to which is added peroxide catalyst. The resulting film is then used to coat furniture parts by applying resin adhesive to a fibrous sheet, after which the film is applied and bonded to the sheet by pressing in a press at a pressure of 10 kilopond / cm for 15 seconds at approx. 140 ° C.

The manufactured product has a hard, smooth surface which is suitable as outer surface of shelves and cabinets.

EXAMPLE 2 2

A paper weighing approx. 100 g / m of bleached sulphate cellulose is impregnated in the middle of the drying section of a papermaking machine in a 2-inch bath of melamine resin in an amount of 40 g / m, and the surface is rendered a mask luster. The melamine resin used is 15 Kauramin® 772 (an aqueous solution of a condensation product of urea and formaldehyde) together with 0.025% by weight of formic acid as catalyst. After the final drying, the paper has a surface weight 2 of 140 g / m 2. The porosity is 35 seconds / 100 ml according to Gurley. Then, the paper is coated in two steps with a titanium dioxide pigmented 2 20 melamine solution. The amount applied is 25 g / m. The film is pressed as described in Example 1 with wet glue onto a fiberboard. This is used for interior lining of kitchen elements.

EXAMPLE 3 2

A paper weighing 120 g / m of bleached sulfate cellulose is impregnated with 40 g / m urea resin in the middle of the drying section of a paper making machine in an inserted glue press. The urea resin used is Kaurit® 210 (a liquid condensation resin of melamine and formaldehyde).

Claims (3)

145723 A dried sample taken after the glue press shows a porosity of 50 seconds / 100 ml according to Gurley. After further drying, the paper is coated in a scraper coating device inserted into the 9 papermaking machine with 20 g / m 2 of a coating paste wherein the pigment is 50% titanium dioxide and 50% clay and the binder is an acrylate latex dispersed in water. The finished foil is used, after final drying, in a similar manner as in Example 1 to coat the inside of cabinets and wardrobes. Similar results are obtained by using unbleached sulfate pulp 10 to form the paper web and by using bleached or unbleached sulfite pulp. A method of making a foil for use as a decorative coating material for a substrate, wherein a process impregnated with a hardenable resin resinous web is coated with a mixture of pigment and binder, and optionally also a dye, characterized in that: a paper web is used which is made by impregnating a cellulosic fibrous sheet material in a papermaking machine prior to final drying with the curable resin resin used in an amount of 5-60% by weight of solids based on the weight of the impregnated paper web, the preparation being carried out in such a way that the paper web is communicated with a porosity according to Gurley of at least 12 seconds / 100 ml. Process according to claim 1, characterized in that the impregnating agent used is used in an amount of 15-40% by weight of solids, based on the weight of the impregnated paper web. Process according to claim 1 or 2, 30, characterized in that an aqueous resin solution or dispersion is used as impregnating agent.