DE1909035A1 - Coating flat articles with polymerisable - mixtures and hardening - Google Patents

Abstract

Flat articles, particularly slabs, of absorbent materials (wood, cardboard, asbestos) are wetted or soaked wit a liquid consisting of one or more liquid, polymerisable organic compounds, pref. methyl methacrylate; one or both uter surfaces of the article are coated while wet with an even layer of a finely divided, spreadable thermoplastic (co)polymer or polymer blend which is soluble or swells in the liquid, such as methyl methacrylate (co)polymer; and subjected to high temps. and pressures.

Description

Method for tempering molded bodies The invention relates to a Process for tempering, in particular the surface of molded bodies, in particular Plates, by treating with polymerizable mixtures and curing under pressure.

Materials made of at least absorbent material, such as wood, cardboard, pressed cardboard, porous rock, asbestos cement, hard fibers, etc.

are widely used in industry and technology for the most diverse Purposes used. These materials, some of which are quite inexpensive, are disadvantageous weight that they do not always meet the increasing demands, especially regarding in terms of quality and appearance.

For example, often the resistance to external influences leaves to be desired. The application of protective films is very complex and leads besides, not always to the desired destination.

So is z. B. for a good wood coating in the traditional sense a solvent-based clear lacquer, even with multiple primers Top coat required to obtain an even, dense surface. Here Even with the use of good lacquers, a film thickness of three times is achieved only 50 to 100> achieved.

The reactive enamels based on unsaturated substances brought an improvement Polyester resins that, in a single casting process, paint film thicknesses of up to approx 200 and 300 p made possible.

However, it is disadvantageous here that in many cases there is also one primer is required and some exotic woods, the larger amounts of which inhibit polymerization Have ingredients that are not usable. Depending on the surface finish requirements of the paint film is a subsequent sanding and polishing for shiny surfaces necessary. Matt surfaces can only be matted up to a certain degree by spraying on the polyester varnish using appropriate matting agents be achieved. For curing, which often takes several times at temperatures of 20 to 400C Hours must be carried out, dust-free rooms are required.

It has now been found that flat shaped bodies, in particular Plates, made of at least weakly absorbent material with the aid of polymerizable substances, possibly with the use of one or two surface decorative layers, can be produced if the shaped body and, if appropriate, the decorative surface layer wetted with a liquid or preferably soaked, which essentially consists of one or more liquid, polymerizable organic compounds and preferably polymers dissolved therein and, if appropriate, plasticizers dissolved therein and / or Polymerization accelerators and / or initiators or hardeners, if appropriate the decorative surface layer or layers placed on the molded body, one or both outer surfaces of the molded body as completely as possible in the moist state and in an even layer with a finely divided, scatterable9, preferably pearl-shaped, thermoplastic polymer which is soluble or at least swellable in the liquid, Copolymer or polymerization mixture covered, with the decorative layer prior to application, the shaped body is subjected to this polymerization on one or both sides can be covered and then, optionally after an intermediate storage, the shaped body exposed to increased temperature and pressure.

According to this process, not only is the production more level, but slightly profiled moldings are also possible.

The inventive method can also with the use of a Surface decor layer can be carried out. These layers are intended primarily convey a certain visual impression. So they don't serve to make one Layer structure that would mean reinforcement of the entire body. In contrast, the treatment with the polymerizable mixture, or. the application of the polymer, primarily the increase in quality. This treatment alone can also give the surface of the molding a better appearance to lend. Veneers, decorative fleeces, Decorative papers etc. in question. So it is always a question of relatively thin-layered ones Materials. Wood, in particular, are used as at least weakly absorbent materials Plywood, paperboard, pressboard, hardboard, porous rock, asbestos cement and like that in question.

The wetting, or the soaking, the shaped body and optionally the decorative layer with the polymerizable organic liquid can be simply Immersion or storage take place briefly or over a longer period of time, depending on whether you only have a superficial or as extensive a penetration as possible wishes. Optimal filling is achieved by treating with a liquid that is in an evacuable vessel. Here you let on the liquid and alternating negative pressure and normal pressure on the immersed parts until the weight is constant act. After wetting or soaking, the decorative surface layer can optionally be applied place on the molded body, preferably after the excess has dripped off Liquid, but still in the moist state of the molding, should take place. In the event of if a decorative surface layer is also used, it is advisable to use the surface adapt to the absorbency of this layer, d. H.

To be kept resin-rich enough to ensure even saturation. Of course, you can also use a decorative surface layer, which in turn wetted or soaked in the same way with the polymerizable liquid has been.

The coating with the polymer can immediately after the wetting, Impregnation or full loading with the monomer, if necessary after application of the Decorative layer, advantageously carried out after a slight drip. She can get through simple sprinkling by hand or with the help of appropriate devices, e.g. B. Scattering or spraying devices are made. It is also possible to use the polymer particles to be applied in a fluidized bed or by immersion, the fine polymer particles adhere to the damp surfaces and form a practically coherent layer there, which is further promoted by swelling or dissolving.

Depending on the type of decorative layer, it is often beneficial to penetrate it Sprinkle the finely divided polymer on both sides of the decorative layer before laying it on.

The loaded and sprinkled shaped body is then optionally after temporary storage in a heatable press, of the conventional type can be exposed to increased pressure and temperature. This will make the polymerizable organic compound cured and at the same time ~ the polymerizate particles converted into a smooth layer with a good bond to the substrate. The finished So bodies are not just primed or impregnated or with a plastic filled, but also at the same time with a tempered, uniformly thick surface layer Mistake. The outer surface can be glossy or with any profiling, how different roughness or arbitrary plowing are formed9 depending on which surface formation is used for the press plates or insulating foils used when hot pressing.

Come as monomeric, liquid, polymerizable, organic compounds those in question which have one or more carbon-carbon double bonds. To be emphasized here are vinyl compounds and their substitution products, such as butter dor acrylic and methacrylic acid, acrylonitrile, styrene and its derivatives or their mixtures. Substances that act as crosslinkers, such as divinylbenzene, triallyl cyanurate, Allyl methacrylate, methacrylic acid esters of glycols and polyalcohols, etc., can also be present. Also unsaturated polyesters, especially in blends with monomers polymerizable thereon can be used.

Methyl methacrylate is preferred.

The liquid polymerizable organic compounds mentioned can preferably also contain polymers in solution. These can be polymers or copolymers of said monomeric compound and also in the monomers soluble elastomers, synthetic resins or natural resins. Examples are polybutadiene tind its copolymers with styrene and X or acrylonitrile, kotone-aldehyde condensation resins, Tall resins, etc.

It is also possible, in a manner known per se, by partial Polymerization prepared, optionally syrupy prepolymer. The production of such prepolymers is described, for example, in the German Auslegeschrift 1,083,057 and in French patent specification 1,221,537.

The content of polymeric substance depends on in all cases the material used for the treatment. Bb can therefore go very further within Limits vary.

The liquid, polymerizable, organic compounds can also other additives known per se, such as stabilizers, dyes, flame retardants Contains compounds, water repellants, UV absorbers, plasticizers, etc.

The hardening of the liquid, polymerizable, organic compounds takes place in a manner known per se by exposure to elevated temperature, preferably in the presence of an initiator, e.g. B. an organic peroxide or an azo compound. Redox systems can also be used.

The level of pressure and temperature to be used depends on the type of monomers and polymers used and on the thermal stability of the material to be treated. Generally the temperature is between 0 and 200 ° C; temperatures between 100 and 1500C are preferred, which is a Allow suitable fast work without already thermally using the material to harm.

The thermoplastic polymers to be used for the covering, Copolymers or polymer mixtures must be so finely divided that they can be scattered are. For example, this shape can easily be achieved by grinding the polymers or a correspondingly fine bead polymer is used. In general the particle size should not exceed 0.5 mm.

As polymers, besides polymethacrylic acid methyl ester and the preferred copolymers from L'stern der Aletllacryls.iure also the polymers of the other monomers mentioned, provided they are soluble or swellable, used will. You can use other Zttsätze known per se such as tJV absorbers, dyes, Contain plasticizers, flame retardants and water repellants.

When pressing the moldings with glue, it is advisable to proceed in such a way that initially only a low contact pressure is applied while the higher pressure take place only after a certain solidification of the polymer layer target. The pressing can be done in a manner known per se from Separating foils take place. You can use foils with a certain surface finish use so that the polymer layer has a corresponding appearance.

To avoid warping of the parts after hardening: it is It is advisable to largely cool the molded parts under pressure.

Example 1 A 380 g sheet of plywood (400 x 400 x 3.5 mm) from three layers of veneer with a cover veneer from Limba is made into one for 30 minutes Dipped filling liquid of the following composition: 86 parts by weight. of a prepolymer 70 parts by weight Methyl methacrylate risates made from: (MMA) 30 parts by weight. 2-ethylhexyl methacrylate 0.3 part by weight Octyl mercaptan and 0.03 parts by weight. Azoisobutyric acid dinitrile (AIBN) 14 Parts by weight a mixture of 70 parts of methyl methacrylate and 30 parts of 2-ethylhexyl methacrylate 0.2 part by weight W absorber 1, O part by weight. Lauroyl peroxide paste (50%) and 1.0 part by weight. Diacetyl peroxide solution (25%) (viscosity of the filling liquid 230 cP.) The production of the polymer takes place with stirring in a one-pot reaction, the AIBN in the total amount is added as a solution in monomeric MMA at an internal temperature of 75 ° C. the Reaction temperature inside the batch is about 100 ° C held. After a total reaction time of 36 minutes, the mixture is cooled and with 40 ppm of hydroquinone stabilized.

After removing and draining the plywood sheet, a Measured weight gain of 90 g. The still moist bottles become even with a bead polymer made from 80 parts by weight. Butyl methacrylate and 20 parts by weight. Methyl methacrylate sprinkled. The grain size of the pearl material is less than 0.5 mm.

The amount sprinkled on both sides is long.

After sprinkling, the plate is sandwiched between silicone release paper that a surface roughness similar to the natural wood of the untreated panel placed around in a press heated to 1300-C. During the first 7 minutes, the heating plates of the press are brought together only so far that - to the treated plywood sheet creates only a slight contact pressure. After 7 minutes a specific pressure of 38 kg / cm2 is set and for 10 minutes held. After the subsequent cooling to approx. 400C, the pressure is released.

The plate has a uniform, 0.25 mm thick, colorless surface on both sides Surface coating made of polymethacrylate with rough, similar to untreated wood Surface formation and good anchoring to the substrate.

Example 2 The procedure described in Example 1 is followed. Instead of however, the plywood sheet is made of pressed cardboard measuring 70 x 75 cm and 4 mm thick used with an initial weight of 2,150 g.

After 30 minutes of storage, a weight increase of 500 g is measured. The amount of bead polymer sprinkled on is 300 g.

After a heating time of 7 minutes under contact pressure, a specific one becomes Pressing pressure of 25 kg / cm2 set and held for 10 minutes.

The plate obtained after cooling and relieving has a uniform, 0.25 mm thick polymethacrylate layer. It has good persistence against water and weather influences.

Example 3 The procedure described in Example 1 is followed. Instead of However, the plywood sheet will be a 40 x 33 cm and 9 mm thick asbestos-cement sheet used.

The initial weight of the plate is 1,200 g. After 30 minutes of storage a weight increase of 200 g is measured. The amount of bead polymer sprinkled on is 100 g.

A glossy polyterephthalate film is used as a separating film during pressing used. After a heating time of 7 minutes at contact pressure, a specific pressure is achieved of 35 kg / cm2 and held for 10 minutes.

After cooling down and relieving the load, the plate is removed. On both sides the plate has a high-gloss, muddy, colorless polymethacrylate layer with a good connection to the subsurface.

Example 4 A 15 x 15 cm, 1.9 mm thick cardboard plate is made Immersed in the liquid described in Example 1 for 15 minutes. To the still damp surface will be on one side. a thin decorative fleece (0.12 mm) in a thickness of 4d; g / m2 with wood decor, applied. This was previously also dipped briefly in the liquid to soak and the excess Liquid stripped off.

Then both sides were evenly made with a bead polymer 92.5 parts by weight Methyl methacrylate and 7.5 parts by weight. Butyl acrylate sprinkled.

Starting weight: 32.6 g cardboard, 1.1 g decorative fleece Weight increase: for both parts a total of 30.5 g of soaking liquid sprinkled on in total for both Pages 5.5 g amount of pearl: A glossy polyterephthalate film is used as a separating film used. After a heating time of 7 minutes at a hot plate temperature of 1400C under contact pressure, a specific pressure of 17 kg / cm2 is set and held for 10 minutes.

The plate obtained after cooling down and relieving the load has both sides a high-gloss, even surface, one side with wood-like decoration, one side with the original cardboard coloring. The surface insists on both Pages made of an evenly thick, colorless polymethacrylate layer.

The finished plate has a thickness of 2.4 mm and shows a very good one Wet strength, after prolonged spraying with water, the water pearls completely from the surface. The untreated cardboard panel, on the other hand, sucks up immediately and swells strongly.

Example 5 An 8 mm thick and 40 x 40 cm large hardboard is used in a filling liquid of 100 parts by weight. the liquid used in Example 1 and 5 parts by weight Treated acetyl tributyl citrate, with a vacuum for 15 minutes of 30 Torr and then normal pressure is set for 1 hour.

After removing the plate and scraping off the excess Both damp sides are liquid with a bead polymer made of 80 parts by weight. Butyl methacrylate, 20 parts by weight.

Methyl methacrylate and 0.2 part by weight. Evenly sprinkled UV absorber and then with a soaked decorative paper (wood type teak, 120 g / m2 thickness) proven. The decoration paper is impregnated by dipping it into the Filling liquid for about 5 minutes. After taking it out, the excess liquid stripped off. Finally, the surface is still damp of the applied decoration paper evenly sprinkled with the pearl polymer.

The plate is then placed between two silicone release papers in the press heated to 1300C, using only a slight contact pressure for the first 7 minutes and then a specific pressure of 28 kg / cm2 for 7 minutes. It is then cooled to about 400C and relieved. The board obtained has a wood-like appearance with a hard, rough and stable surface with increased inherent strength. Picked up scattered Starting weight Amount of FUll Amount of pearl fluid material ' Hardboard. 1 370 g 325 g 35 g Decorative paper 1 10 g 95 g 25 g 2 8 g 107 g 30 g Example 6 3 spruce wood boards 150 cm long, 9.7 cm wide and 10 mm thick are treated after drying (1 day at + 100 ° C) in the liquid used in Example 5, with a vacuum of 30 minutes for 30 minutes Torr and then normal pressure is set for 2 hours.

After removing the boards and draining them, they will still be damp Surfaces sprinkled with the pearl polymer used in Example 5 and then sprinkled with a side distance of about 5 cm next to each other between silicone release paper with a rough surface in the press at 125 ° C, with during the first 7 minutes only light contact pressure and then 7 minutes a specific pressure of 12.6 kg / cm2 is set. It is then cooled to about 400C and relieved.

Percentage weight increase calculated on 100 g of dried spruce wood: Board after loading after loading after after designing No act in the scattering with pressing distant of the Liquid squeezed out of pearl material Polymer edge 1 16.7% 29.6% 27.2% 22.4% 2 17.3 * 28.5% 26.4% 21.5% 3 19.4% 30.8 ffi 28.8 ffi 24.1 * The boards have a colorless polymethacrylate layer on both sides with high hardness, resistance and good anchoring to the substrate.

Example -7 2 pieces of teak veneer each (120 x 110 x 0.6 mm) and one piece of pressed cardboard (4 mm thick) are filled with a liquid of the following composition: 86 parts by weight. of a prepoly 70 parts by weight. Methyl methacrylate merisates from: (MMA) 30 parts by weight. 2-ethylhexyl methacrylate 0.3 part by weight Octyl mercaptan and 0.03 parts by weight. Azoisobutyric acid dinitrile (AIBN) 14 Parts by weight a mixture of 70 parts of methyl methacrylate and 30 parts of 2-ethylhexyl methacrylate 0.2 "UV absorber 1.0" lauroyl peroxide paste (50%) and 1.0 "diacetyl peroxide solution (25%) viscosity of the filling liquid 230 cP.

The prepolymer is produced under tubes in.

a one-pot reaction, with the total amount of AIBN as a solution in monomeric MMA at an internal temperature of 75 ° C is added. The reaction temperature inside the approach is kept at about 1000C. After 36 minutes total reaction time is cooled and stabilized with 40 ppm hydroquinone.

This is done at about 40 Torr for 10 minutes after immersion evacuated and then normal pressure set for another 10 minutes.

After taking out and draining, the teak veneers are on je one, namely the side provided as the outer surface and the pressboard on both sides evenly with a pearl polymer made of 80 parts by weight. Butyl methacrylate and 20 parts by weight.

Methyl methacrylate sprinkled. The grain size of the pearl material is less than 0.5 mm. Initial load Scattered amount weight pearl material g% g Teakfiinter 4.0 145 2.0 Teak veneer 4.1. 122 2.7 Preas board 55.0 2 & t3 1.2 After sprinkling, the plate is placed between silicone paper, which has a surface roughness similar to that of the natural wood of the untreated veneer, and placed in a press heated to 130oC. During the first 7 minutes, the press plates are only moved together to such an extent that there is only a slight contact pressure on the layered plate. After 7 minutes, a specific pressure of 6.8 kg / cm 2 is set and maintained for 10 minutes. After cooling to 50 ° C., the pressure is released.

The plate obtained shows a very good bond between the individual Layers. When attempting to split, break occurs in the material and not in the connecting layer a. The surface is more even, more similar to the untreated veneer Roughness and has good wet strength and resistance to weathering.

Example 8 A 40 × 30 cm and 9 mm thick asbestos cement board together with a 40 × 30 cm and 0.6 mm thick mahogany veneer is immersed in the soaking liquid described in Example 7 for 30 minutes. Starting weight Weight increase after the draining Asbestos cement board 2 010 g 95 g Mahogany veneer 30 g 85 g One side of the asbestos cement board and one side of the veneer is evenly sprinkled with 20 g of the bead polymer used in Example 7.

The two parts are then layered so that 'the unspread The side of the veneer comes to rest on the strewn side of the asbestos sheet. the The sprinkled veneer side thus forms an outer surface.

The direction is carried out as described in Example 7 between rough Silicone paper with the same temperature and curing time. After contact printing will However, a specific pressure of 25 kg is set.

The finished panel shows a good bond between the two layers. The veneer side has an even, rough surface layer corresponding to the paper Made of Pclymethacrylat with good resistance and wet strength.

Example 9 An 8 mm thick and 15 x 15 cm large hardboard is used with a filling liquid consisting of 100 parts by weight. that used in Example 1 Liquid treated 10 "acetyl tributyl citrate 10" allyl methacrylate, while A vacuum of 30 torr for 10 minutes and then normal pressure for 10 minutes will.

After removing the plate and scraping off the excess Both damp sides become liquid with the bead polymer used in Example 5 Evenly sprinkled, then one side is covered with a decorative paper (type of wood Teak, 120 g / m² thickness). The decoration paper was impregnated through even storage together with the hardboard. After taking it out The excess liquid is also removed from the decoration paper. Finally, the still damp surface of the applied decoration paper evenly sprinkled with the pearl polymer.

The plate is then placed between two silicone release papers 13,000th heated press, whereby. Immediately a specific pressure of 4 kg / cm2 is set and held for 10 minutes. After cooling down to about 40 ° C is relieved.

The board obtained has a very uniform and hard surface, an appearance similar to wood on one side with increased inherent strength and resistance to weathering. Scattered initial weight ingested Filling liquid quantity pearl G g material (g) Hardboard 145 36 5 plate Decorative 3 6 4 paper

Claims (4)

P a t e n t a n s p r ü c he 1. Process for tempering flat Moldings, in particular Plattenfaus at least weakly absorbent material with With the help of polymerizable substances, if necessary with the use of an or two decorative surface layers, characterized in that the molded body and optionally wetting the decorative surface layer with a liquid or preferably soaks, which essentially consist of one or more liquid, polymerizable, organic compounds and, preferably, polymers dissolved therein, and optionally plasticizers and / or polymerization accelerators and / or initiators dissolved therein or hardeners, if necessary. the surface decorative layer or layers placed on the shaped body, one or both outer surfaces of the shaped body in the moist Condition as complete as possible and in an even layer with a finely divided, scatterable, preferably pearl-shaped, soluble in the liquid or at least swellable, thermoplastic polymer, copolymer or polymer mixture occupied, with the decorative layer on or before being placed on the molded body Can be covered on both sides with these polymers and then, if necessary after intermediate storage, the molded body exposed to elevated temperatures and increased, exposing prints. 2. The method according to claim 1, characterized in that one essentially of methyl methacrylate and preferably methyl polymethacrylate listed therein existing liquid used. 7. The method according to claims 1 or 2, characterized in that - that the liquid is produced in the form of a partial polymerization, optionally syrupy prepolymer used. 4. The method according to claims 1 to 3, characterized in that that the dispersible polymer material is polymethacrylic acid methyl ester or preferably a copolymer of esters of methacrylic acid is used.