DE1282975C - Manufacture of laminates - Google Patents

Description

DUTCH REPUBLIC OF GERMANY

DFUTSCHES

PATENT OFFICE

PATENT LETTERING

Int. Cl .:

rO8j-i / 36

B 32 w-27 / H)

German class: 39 b7-1 / 36

39 a3-9 / 00

Number. 1282 975

File number: P 12 82 975.3-43 (H 55571)

Filing date: March 25, 1965

Open date: November 14, 1968

Issue date: December 30, 1971

Patent specification deviates from the Auslegeschriit

It is known that polyvinyl alcohol can also be used in the condensation of melamine with formaldehyde. It is also known that the melamine resin solutions used for impregnation purposes are polyvinyl alcohol Add thickener to adjust a certain viscosity. Finally one has melamine resins have already been modified by adding polyhydric alcohols during condensation. This can have a beneficial effect on the flowability and other properties of the finished resins will. One works under such conditions that the polyhydric alcohol is chemically in the Resin is bound. It is also known to use thermosetting resins such as urea-formaldehyde resins, together with lower polyhydric alcohols and ethyl hydroxyethyl cellulose in aqueous Solution for impregnating fibrous materials as well as paper and using the impregnated products to be pressed hot after drying (French patent 1 108 129).

However, the Har.'j which can be produced by the known processes show when used as a binder for laminate there are various disadvantages. So allow the transparency of the surface to be desired. The surfaces also often have poor resistance to cracking. Also observed the still warm pressed parts are often glued to the press plates.

The subject of the invention is a process for the production of laminates, whereby papers are used with an aqueous melamine resin solution soaks, the lower polyhydric alcohols and also a polymeric, OH-containing compound, then dries as usual and on carrier materials presses on. The process is characterized in that one uses a melamine resin solution impregnates the polymer, OH group-containing compound 2 to 2O% - based on solid melamine resin - Polyvinyl alcohol with a saponification number of 50 to 250 and still as lower polyvalent ones Alcohols ethyl glycol, propanediol, butanediol, glycerine, Contains diethylene glycol, triethylene glycol, mannitol or sorbitol.

Aqueous liquors of melamine form (^. nuildchyd precondensates are used, in which the molar ratio of melamine to formaldehyde is approximately between 1: 1.5 to 1: 2.5. The precondensate is expediently at a pH -Value from 7 to 10 and (M a temperature of about 60 to 100 ⁰ C condensed up to a »-Η precipitation number of about 10 to 1. For ^ ₄ impregnation the Melamiiiformiildchyü-VorkondtMi- ^ sat-FloHc should have a Feststolfgehall of about 50% on-making laminates

Patented for:
Henkel & Cie. GmbH.,

4000 Düsseldorf-Holthausen, Henkelstr. 67

Named as inventor:

Kurt Rehnelt, 4000 Düsseldorf-Holthausen;

Dipl.-Chem. Dr. Manfred Voss, 4010 Hilden -

point. You can prepare the impregnation solution from melamine and formaldehyde or dry Dissolve melamine resin in water.

About 2 to 20 ° / n are added to the impregnation solution,

especially 5 to 15% of polyvinyl alcohol, based on solid melamine resin. According to the saponification number, the polyvinyl alcohol still has an initial content of acetyl groups. It is expedient conces- in the form of an aqueous 30 to 50 ⁰ / o solution

»5 places.

Furthermore, the resin liquor is still the lower ones polyhydric alcohols ethylene glycol, propanediol, butanediol, glycerine, diethylene glycol, triethylene glycol, Mannitol and sorbitol too.

The impregnation solutions expediently contain about 60 to 20%, but especially about 50% water.

Papers of about 15 g to 150 g / m ² can be used as papers for impregnation. One can thus on the one hand so-called overlay Seidenpap'ere with about 15 to 50 g / m ^ä use, namely bleached as well as unbleached, on the other hand, so-called decorative papers, which generally have a weight of about 70 to 150 g / m ^2. The latter can be filled or unfilled and be in printed or unprinted form.

The papers are expediently impregnated in devices known for this purpose in a continuous manner. The temperature of the impregnation solution can in this case 10 especially 20 to 40 ⁰ C amount, up to 60 ⁰ C. It is also possible to impregnate the papers in batches.

The concentration of the impregnation solution, the temperature and the other conditions are set so that that in the Ovcriay Papers there is a resin deposit

So drying from 200 to 4 () Ο · / ο des Papicrgcwiciilcs is present, for the decor paper an order of 80 to 20 (l «/. I, luvogeii nuf the paper weight.

Claims (1)

i 2ö2 After soaking, the wet paper by means of hot air /.wischen 80 and 150 ¹ C dried, optionally after pre-drying by means of infrared radiation. The dried papers can be pressed directly. But they can also be stored for a longer period of time. To produce the laminates, the impregnated and dried papers are then pressed onto carrier materials. Wood materials such as chipboard, plywood, solid wood or laminates that are bonded with other condensate resins, such as phenolic resins, come into question as such. The compression is carried out at a relatively low pressure of about 5 to 20 kg / cm ² , preferably 6 to 13 kg / cm ² , and a temperature of 120 to 200 ^° C., in particular 130 to 180 ^° C., from. Pressing times of about 30 minutes, but in particular 1 to 15 minutes, are required. The pressing conditions vary with the degree of condensation of the melamine-formaldehyde resin and the amount added and the nature of the polyvinyl alcohols. The technical progress of the process according to the invention can be seen in the fact that when it is used the papers impregnated according to the invention »5 opened the presses with practically no recooling can be and are therefore available for a new load after a very short time. Farther the surfaces of the laminates available have good transparency and a «; closed 3 » Surface that can withstand high temperatures. Used in place of polyvinyl alcohol If hydroxyethyl cellulose is used, the surfaces are cracked and tear when exposed to high temperatures continue one. Since when using hydroxyethyl cellulose or ethyl hydroxyethyl cellulose, as it is according to the prior art was known in the art for thermosetting resins, melamine resins !! only laminates with cracked ones Surfaces result could not be expected that with otherwise the same procedure with polyvinyl alcohol particularly good results would be obtained. example 1 45 500 kg of mclaminformaldehyde precondensate (molar ratio 1: 1.7, filling number 3.0) were dissolved in 5W ', water, and 100 kg of a 50% solution of polyvinyl alcohol with a saponification number of I 10 were added. 55.0 kg of ethylene glycol were added to this. A white titanium dioxide-coated paper of 80 g / m ^{2 was} impregnated with this solution and dried at 120.degree. A resin absorption of 140 "o was achieved. This paper was pressed onto chipboard at a pressure of 12 kg / cm * for 7 minutes. The temperatures were 120, 130, 140 and 150 ^° C. In all cases, transparent surfaces were obtained, which could be detached from the bleci.cn without sticking. Example 2 Example 1 is repeated, but with the difference that instead of 100 kg, only 50.0 kg of the 50% polyvinyl alcohol solution were used. The results were practically the same as described above. Example 3 An impregnation solution according to Example 1 was produced and a highly bleached cellulose paper of 25 g / m 2 was impregnated with it. The resin uptake was 270%, based on the weight of the paper. The impregnated at 130 C paper was pressed under a D · .ick of 12 kg / cm ² at 150 ⁰ C for 10 minutes to plywood. A highly transparent surface was obtained, which clearly showed the natural wood grain. Example 4 500 kg of melamine-formaldehyde precondensate (molar ratio 1: 1.6, precipitation number 6.0) were dissolved in 500 l of water and 80 kg of a 50% solution of polyvinyl alcohol with a saponification number of 78 were added. To this, 50 kg of ethylene glycol were added and ^{papers with a weight of 120 g / m 2} and printed with a walnut pattern were impregnated with the solution obtained. Drying was carried out at 120 ⁰ C, and it was achieved :: ne resin uptake of 140%>. The papers were pressed onto plywood panels at a pressure of 10 kg / cm * for 8 minutes. Transparent surfaces were obtained which could be detached from the metal sheets without sticking. Patent claim: Process for the production of laminates, whereby papers are treated with an aqueous MclaminharzlöMing soaks, the lower polyhydric alcohols and also a polymer, OH-group-containing Contains compound, then dries as usual and presses onto carrier material, characterized in that it is impregnated with a melamine resin solution, which as polymer compound containing OH groups 2 to 20%, based on solid Mclaminhar /, polyvinyl alcohol a saponification number from 50 to 250 and, as lower polyhydric alcohols, ethylene glycol, Propanediol, bulanediol, glycerin, diethylene glycol, triethylene glycol, mannitol or Sorbitol complies. Considered publications:
French patent specification No. 1 108 120,
Ullmunn's Encyclopedia. der technical chemistry, 3rd edition, 14th volume, p. 239. Mt U7 / MJ 11. M ftuodetdftKktnl BttUa