DE1059808B - Coating of absorbent substrates treated with wax, wax mixtures or wax-like hydrocarbons - Google Patents

Description

Coating of absorbent substrates treated with wax, wax mixtures or wax-like hydrocarbons. It is common practice to use absorbent materials, e.g. B. wood, hardboard or chipboard, cardboard, paper, to treat for various reasons with waxes or wax mixtures. However, such wax impregnations prove to be very annoying if such substrates are to be painted later. It is known that oil and oleoresin varnishes of the usual type and oil alkyd resin varnishes, which dry so-called siccatives chemically by the action of atmospheric oxygen with catalytic participation, dry very poorly on raw wood pretreated with wax and give a poorly adhering varnish film. Even mainly physically drying paints based on nitrocellulose and other paint raw materials are considerably impaired in their drying by small amounts of wax present on the absorbent substrate.

To eliminate this adverse effect of the waxes, it is at the conventional lacquers necessary, the substrate by suitable measures, such as washing off to be cleaned with liquids that have high dissolving power and / or sanding. In most cases, sufficient, but not complete, removal of the waxes is achieved, the z. B. with solvents sometimes only deeper into the porous and absorbent Material to be transported.

This disruptive effect of waxes does not manifest itself, though paints based on unsaturated polyester can be used according to the invention. There is then normally no pretreatment of such waxy substrates necessary.

It is known to use waxy substances that form skin, such as ceresin and montan wax, to be used in conjunction with lacquers based on unsaturated polyester, to obtain tack-free coatings. The effect of the waxy substances is based on In this case, ensure that they have a cohesive coating on the paint layer form, which prevents the entry of air and thus the harmful influence of the Turns off atmospheric oxygen during the hardening of the paint layer. According to this state However, the technology was not to be expected that paint layers based on unsaturated Polyester would also adhere perfectly to waxy substrates.

The paints in question are known to contain unsaturated polyesters, the esterification of an α, ß-unsaturated dicarboxylic acid mixed with others saturated dicarboxylic acids and polyalcohols and produced in a liquid monomeric vinyl compound are dissolved. As a, ß-unsaturated dicarboxylic acids are called: fumaric acid, maleic acid or maleic anhydride, itaconic acid, citraconic acid and mesaconic acid. The modification with other dicarboxylic acids is achieved by using of aliphatic saturated dicarboxylic acids, such as succinic acid, adipic acid, sebacic acids, and / or with phthalic acids or other dicarboxylic acids of the aromatic and hydroaromatic series. Instead of saturated dicarboxylic acids can the unsaturated polyester partially also with bifunctional organosiloxanes, z. B. diethoxytrialkyltriaryltrisiloxane, modified. As polyalcohols are in particular dialcohols or glycols are used, e.g. B. ethylene glycol, diethylene glycol, Triethylene glycol, propylene glycols, butylene glycols and even higher glycols and more complicated dialcohols. Are more than bifunctional polyalcohols used in the polyesterification, its functionality is z. B. by sharing of monocarboxylic acids. to decrease that of glycols.

Such unsaturated polyesters are produced in a known manner Way mostly by thermal esterification of the components in the melt flow, whereby the Atmospheric oxygen is to be kept away by inert gases. After the esterification is complete then after the addition of small amounts of inhibitors, usually of a phenolic nature, the unsaturated one Polyester dissolved in a liquid monomeric compound of the vinyl series. Most common is the monomeric vinylbenzene or styrene.

Such an unsaturated polyester mixture is used as a varnish in a known manner shortly before the application with radical-forming organic Links, mainly organic hydroperoxides or peroxides, added as catalysts. There are the desired peroxides or in terms of drying temperatures Hydroperoxides selected, their disintegration in a known manner by very small additives promoted by accelerators such as soluble cobalt soaps or dimethylaniline. Such unsaturated polyester blends can also be obtained by adding small amounts Amounts of low boiling solvents, e.g. B. acetone, to the desired spray or exchange consistency can be set, but spray application is preferred.

Such jobs dry with the selection of suitable ones Catalyst systems operating at room temperature in the course of a relatively short time to hard, tack-free lacquer films, which as a result of polarization reactions unavoidable volume loss a restless, but not smeary surface own. However, sanding and buffing or buffing can create a shiny finish Achieve coatings. Example 1 consisting of 100 parts of unsaturated polyester blend from 65 parts of polyester and 35 parts of styrene, 10 parts of styrene and 3 parts of a 1%: metal-containing cobalt naphthenate solution in styrene will work well with one another stirred. Shortly before processing, this mixture is mixed with 7.5 parts of a 40 ° / a Methyl ethyl ketone hydroperoxide and a mixture containing 60 "/ o dimethyl phthalate are added and with a little acetone to spray consistency (processing time in the DIN cup: 20 to 22 Seconds).

A hardboard treated with paraffin wax during manufacture is sprayed over with this varnish without any pre-treatment. The coating dries without Glue with good adhesive strength and with a somewhat restless and honeycomb structure showing Hard surface in a few hours. After grinding and polishing a A thick, glossy layer of varnish is preserved. Example 2 One with walnut top veneer plywood panel is lightly treated with liquid floor wax. To The board is sprayed over with the polyester lacquer mixture from Example 1 after it has flashed off. The polyester layer dries tack-free in a few hours. The existing Surface structure can be easily made by sanding and polishing or buffing remove. A glossy paint film with good body is then obtained.

Example 3 A plasterboard is made with a paraffin-heavy gasoline solution rubbed off. After flashing off, the sheet is covered with the polyester varnish mixture of the Example 1 overmolded. The polyester layer dries with a relatively good overnight and tack-free surface hard through, so that only a slight aftertreatment sanding and buffing is required.

Example 4 A chipboard that was manufactured with paraffin wax is treated with that described in Example 1 without any pretreatment Paint mixture sprayed over. After just one application, one is applied to the absorbent A layer standing on the ground is achieved, which is glossy and tack-free with some surface structure hardened. After sanding and buffing, it becomes shiny and full-bodied Paint layer received.

Claims (1)

. PATENT CLAIM: Use of lacquers based on unsaturated polyester resins for covering absorbent substrates treated with wax, wax mixtures or wax-like hydrocarbons. Documents considered: French Patent No. 1061133.