NO143933B - WITH HARDWARE ARTIFICIAL RESINS IMPREGNATED AND COATED BEAR MATERIAL COURSE FOR SURFACE PROCESSING OF TREMATERIALS, AND PROCEDURES FOR PRODUCING THEREOF - Google Patents

Description

This invention relates to a carrier material web impregnated and coated with hardenable synthetic resins and a method for its production. The invention is stated in the claims, and reference is made to these.

It is known to impregnate carrier webs, in particular plain-coloured or print-decorated paper webs, with heat-curable aminoplast or phenoplast which is dissolved in water or a water-alcohol mixture, and then dry the resulting films or coating webs. These are intended to be connected to each other or to wooden materials, such as chipboard, fibreboard and plywood, using pressure and heat.

The amount of resin that is applied to the carrier during the impregnation is normally sufficient to effect a firm connection with

the substrate; in many cases, a coat of glue or an adhesive membrane is also applied between the substrate and the hardenable synthetic resin membrane in addition to the resin impregnation.

It is also known that it is possible to carry out the impregnation

with aminoplast or phenoplast in two or more consecutive steps, where the various impregnation steps are carried out with resins which are mutually different in terms of composition, viscosity and reactivity.

In the case of high-quality coating materials, especially coated wood materials, it is also common for the coating to be built up from several layers, under which aminoplast or phenoplast-impregnated paper layers are applied one after the other or simultaneously. With this method, a distinction is made between paper that is "underlay", decorative paper and "overlay".

However, the coating of wood materials with artificial resin membranes applied to a carrier is not limited to the use of aminoplast or phenoplast. Other polycondensable or polymerizable resins have been used or proposed; in particular, it is already known to impregnate paper with polymerisable compounds, for example diallyl phthalate (prepolymers) or with crosslinkable polymers of the unsaturated polyester resin type. These coating materials can also be connected to suitable wood materials by means of pressure and heat. An overview of the hitherto known possibilities can be found, for example, in "Moderne Beschichtungsverfahren fur Holzwerk-stoffe" by W. Enzensberger, published in "Holz als Roh- und Werkstoff", volume 27, issue 12.

The known possibilities for surface treatment of wooden materials are extremely versatile. However, the known resin preparations and the technique for their processing are not satisfactory in many cases when the existing mechanical possibilities for the processing are to be utilized optimally. The mechanical processing possibilities are in many cases also narrowed down by the wood material itself and the auxiliaries' own limitations.

For example, by laminating wooden materials and films made on the basis of aminoplast or phenoplast, you cannot achieve surfaces that exhibit the high gloss of lacquered surfaces. For this reason, coated materials, i.e. materials that are provided with a protective layer through the use of pressure and heat, are often provided with a suitable varnish layer in a separate work step and possibly also polished to achieve the desired high gloss.

The possibilities for achieving a surface gloss are particularly narrowed when the coating is carried out with aminoplastic or phenoplastic bonded carrier materials and one uses the economically advantageous so-called short-stroke method, where one foregoes a cooling of the press plates.

Films of unsaturated polyester resins or diallyl phthalate polymers or mixtures thereof have a lacquer-like gloss even without recooling; coating with such resin films, where relatively large amounts of material must be used compared to e.g. painting, however, entails high costs due to the expenses for resin, and the inevitable use of organic solvents is a technical disadvantage of coating methods where it is used unsaturated polyester resins or diallyl phthalate.

Furthermore, polyester resins do not adhere well to carrier materials made of paper or the like, which is why in BRD-off.skrift 2 136 378 it has recently been proposed to produce decorative panels using such resin-treated paper materials whose fibers - possibly already in the paper production stage - are pre-treated with, for example, melamine or urea resins and then impregnated with a polyester resin or a diallyl phthalate resin. In contrast to the present invention, the proposal according to the above-mentioned publication, briefly stated, aims to provide a polyester resin coating with improved adhesion properties. This proposal is not comparable to the present invention,

as here it is mainly an aminoplast resin coating whose surface structure is improved.

The present invention relates to a carrier material which is impregnated and coated with hardenable synthetic resins, for the surface treatment of wooden materials and consisting of a carrier material web which a) is impregnated in a manner known per se with a hardenable aminoplastic or phenoplastic impregnation resin and b) on one side is provided with a coating of an unsaturated curable polyester resin, characterized in that the coating of unsaturated curable polyester resin consists of a solidified mixture of 20-98% of a non-crystallisable and 2-80% of a crystallisable polyester which at room temperature is solidified by thickening through heating poorly soluble in the usual monomers which have a cross-linking effect and which serve as solvents, as well as possibly the usual cross-linking-capable solvents for unsaturated polyester resins. The method according to the invention for producing the carrier material web largely follows the description of the structure of the web material, see claim 2.

The resin preparation used as a coating is referred to in the following for simplicity as "polyester resin mixture".

From the following it will be seen how the invention differs from what is known. It is known that polyesters which are made up of extended symmetrically structured acid or alcohol molecule chains, and therefore contain, for example, fumaric acid, terephthalic acid, adipic acid or sebacic acid units on the one hand and unbranched or symmetrically branched diol groups on the other, such as in ethylene glycol, butanediols (1,4), (generally a,w-polymethylene glycols) or, for example, in neopentyl glycol and in hydroxypivalic acid-neopentyl glycol esters, are crystallizable and are available in solid form in a crystalline state.

These crystalline or crystallizable polyesters are, for known reasons, usually poorly soluble, especially in solvents (monomers) which can be cross-linked, such as styrene, diallyl phthalate or methyl methacrylate, which usually form the solvent base for liquid, unsaturated polyester resins. Furthermore, they are insoluble in the non-crystallisable polyesters which are liquid at room temperature and of course also in mixtures thereof with monomers.

Crystalline polyesters are, for example, described in US Patent Nos. 3,396,128, 3,455,870 and 3,510,457, and reference is hereby made to these. In the latter patent, crystalline polyesters are also referred to as "partially crystalline polyesters", and these too come into consideration within the framework of the present invention.

Polyesters that are more or less statistically made up of

the common ones, especially those of the cheap dicarboxylic acids, for example phthalic acid and corresponding diols, on the other hand, are usually easily soluble

straight or liquid and possibly solidifies in an amorphous (glassy) state. These amorphous polyesters form the vast majority of the usual unsaturated polyester resins used as coating or impregnating agent, and also form the essential raw material for the so-called glass fiber reinforced synthetic resins (GRP).

According to the invention, on the basis of polyester resin preparations and in an improved form, coatings for aminoplast or phenoplast-impregnated (core-impregnated) paper materials are obtained by using one mixture of different, i.e. at least one crystallizable and one non-crystallizable polyester, optionally in corresponding suspension or solution.

Apparently, the crystalline component in the polyester resin mixture here forms a thickening agent of a special kind: During the impregnation process, the crystalline phase forms a relatively easy-flowing suspension; below, room temperature is usually used. Then follows a thickening process, which

is conducted at 50-120°C, and which is followed by a temporary melting of the crystalline phase; after cooling, it forms a network on the newly separated crystalline mass which has a very reinforcing effect.

The polyester resin compositions usually also contain

about. 0.5-5% of an inorganic thickening agent, preferably based on an alkaline earth hydroxide or oxide, which intervenes in the thickening process. It was surprisingly observed that the per se known thickening process of non-crystallizable polyesters, which is assumed to consist of a salt or complex formation between Mg<++->ions and carboxyl groups, is surprisingly accelerated by the addition of even quite small amounts of crystallizable polyester . An amount of 5-40%

of the crystallizable polyester induces this effect in tec-

nish favorable degree.

The coating produced in this way exhibits - before the actual cross-linking reaction by hot pressing - a significantly higher viscosity than a coating produced without a content of crystallizer

bare polyester.

This has, among other things, the following advantage: First, more

or less liquid coating (it usually contains a large amount of free styrene) is covered during the thickening process, usually with

a foil, which is later pulled off, and soitKek-resist.avlerienr.in commercial thermoplastic._polyeste^r../v^The oil can.-after the thickening of the mixtures be drawn a<y> immediately ^ r - ~ y ^. i?A z:iv<:W- <i-after the treatment in yarme^pyn,, .and ^the erring-problems-rmed jad-skiHelsén. ' .........<....... ,r r:.■—->f /..rw~.r . ::.-< v- • .-v.

The viscosity of the coating, for example, can be determined';.véd> _i. ; .

: rL ■.. < • i! fifi i-,-<:v>.i< i ..) <.-.■■ ■_ ■j- t~?-'- ■■ ■•' •-■

with the help of a consistometer (Haake, Berlin), or a suitable device for v in shoes in a small 1 ing. than 10,-<. <cpv.' r One can i;: then "without further processing separate foil free-paper laminates; Wood;

„,-;.••> ,-.v. ~ e'.:■: • ovan u: aai^usuai :>c^ v.jr,... - ■.. ■ the processing achieves further^ advantages .as rb'lant-vannet-nytrer,-to.r. \ se by especially, .even. out floating...- tross j höofy iskpsitet-; ••) and in the formation of surfaces. the quantity •. get- wrong^... It; is-, then;, taken into consideration that the teaching underlying the invention aims at achieving particularly good surface properties. v-.-r

. By. production of arunnbeleggettr-.used! påoi andvfbr themselves

known way aminoplastic j.or cfenpplast^^ r-generally available in-aqueous readingvpg.:g iron >.ererknown as - "impregnation resins" r .-Similarlyr, the.carrier materials are soirif-sfel'"''' - ' impregnated,,/ , especially paper materials, generally considered to be known. One uses, for example, high absorbency, which, depending on the purpose of application, has a weight per square meter between 20 and _2Q0r,g ...and, in ^general, it is recommended cfoflbe- ' - agreed purposes of use ..from the manufacturer's side,.v- 'By -^different purposes of use" is meant here first,,,and.--the main useJsbm under-layer paper (underlay) ,. as: .decorative paper/,-,(mid^lerei:ti-l- t.ungejf qualities); and as overlay paper {.oyerlayij .la^, ky:adra^metery.ekt.r a/:«let.te; quall'-- -f-:-tetér) . ^ , . 0 ia vf.,uo;,0i). -.cM- '^.:,^;..To::.nrUi ^-'

In addition, it includes the use of fur materials for road materials, such as carrier materials, such as these often used in the production of layer materials. ,<v; W* ;In accordance with the objective of the invention; after- ;■ .;.v i-.v:; v ■ > i - i ->v JTT... «•---•' •. ■'" ; action of the aminoplast,-_ or phenoplast-impregnated-support material^.- .: clay with an artificial resin. on the basis. of, a certain: unsaturated-polyester: ' ^ however id^ generally limited : ti 1 such r t« rematerials which will form the outermost or uppermost layer of the final product such as non-crystalline or non-crystallizable polyester resin different . systems are suitable. ; ;>>j •aul.'." ^ A^ ui! j;c.t-.--y...S :■■ ;, Thus, you can use polymerized polyestersMmedietV' • ; • < solid cross-linking agent. , ;further.,,you can.,you can use unsaturated polyesters .:' :: dissolved in a ..liquid f cross-linking agent,. r for example, styrene; f.ogosome' ;contains a thickening agent, such as magnesium oxide. ;As unsaturated, non-crystallizable polyesters, polyesters based on raaleic acid can be used, for example, fumaric acid, tetrahydrophthalic acid as unsaturated dicarboxylic acids; phthalic acids, adipic acid, succinic acid, hexachloroendomethylenetetrahydrophthalic acid and others as saturated dicarboxylic acids; ethylene glycol, propylene glycol, butanediols, neopentyl glycol, hydroxypivalic acid-neopentyl glycol ester, hexanediol-1,6, hydrogenated bisphenol A, dioxalkylated bisphenol A and others such as diols. The resins may also contain smaller amounts of mono- and polyhydric carboxylic acids or alcohols, such as benzoic acid, oleic acid, trimellitic acid, pyromellitic acid, ethylhexanol, trimethylolpropane, glycerol, pentaerythritol and second. The non-crystallizable polyesters are predominantly mixture condensates of the above-mentioned monomers. As is well known, acids and alcohols are normally present in equivalent amounts, however there can be up to 20% deviation from equivalency downwards or upwards. The unsaturated polyesters generally have an acid or hydroxyl number between 20 and 70. By the amount of double bonds in the unsaturated dicarboxylic acid in relation to the total amount of acid and by choosing the alcohol, it is possible to vary the concentration of copolymerisable double bonds in the polyester within wide limits. As the turnover of these double bonds partly determines the cross-linking density, and as one generally strives for a high cross-linking density, the polyester should exhibit a high degree of unsaturation. Particularly advantageous are such non-crystallisable polyesters which at room temperature and in the absence of solvents or monomers are solid and non-sticky, and which, by appropriate selection of the components, respectively the molecular weight of the prepolymers, can be produced without further ado in a manner known per se. ;While the non-crystalline polyester prepolymers, which are solid at room temperature, melt at a temperature usually below 70°C and then go from a glassy state to a liquid state, the crystalline polyesters usually melt or soften only at a temperature above 70 °C. However, a particularly distinguishing criterion is the solubility, for example in styrene, at 20-25°c: While the crystalline or partially crystalline polyesters have a solubility of less than 10%, so that in an amount of more than 10% they always form a suspension with styrene, the non-crystalline polyesters are always more than 10% soluble and usually miscible with styrene in all proportions. Even solutions containing more than 70% polyester in styrene are liquid at 20-25°C. Naturally, the same applies in principle to other monomeric solvents. Particularly suitable polyester mixtures consist of 10-80%, especially 10-50%, of an ethylenically unsaturated polymerizable monomer and 20-90%, especially 50-90%, polyester which consists of a mixture of 20-;98%, especially 60-96%, of non-crystallizable polyesters and 2-80%, especially 4-40%, of crystallizable polyesters. The non-crosslinkable prepolymers' non-stickiness and firmness at room temperature can be achieved by reaction with metal salts, in particular - as mentioned above - metal oxides or metal hydroxides, whereby salt-like bonds are formed between neighboring molecules, so that an apparent increase in molecular weight immediately occurs. The often resinous or sticky products become hard and non-sticky in this way. Cross-linking agents, or monomers, which in appropriate amounts are partly also suitable as solvents, are such ethylenically unsaturated copolymerisable compounds that contain one or more double bonds in the molecule, such as styrene, chlorostyrene, methyl methacrylate, butyl acrylate, diallyl phthalate, divinylbenzene; further pre-polymers of the polyfunctional cross-linking agents with free double bonds, such as for example pre-polymers of diallyl phthalate, which also in and of themselves have film-forming properties or can be cured with known means. As catalysts, such compounds can be used which, under the pressure conditions, i.e. above 100°C, deliver radicals, for example azo compounds, peroxides and others. As additives to both the impregnation resins and the polyester surface resins that are applied according to the invention, inorganic fillers can be used, for example, such as chalk, dolomite, lime, inorganic or organic pigments such as titanium dioxide, silica gels, organic, weakly cross-linked, powdery materials that are to swell strongly, such as partially cross-linked unsaturated polyester resins, further flow aids, thixotropy aids and others. It is a particular advantage according to the invention that the coating or film already with pressing times of approx. 30 seconds using a temperature of approx. 160°c can be pressed onto chipboard and fiberboard without the pressing plates having to be cooled after pressing. With this so-called short stroke method, according to the invention, surfaces with a high gloss are obtained; with conventional amino-plastic binders this has not been possible until now. It is also advantageous that the pressure to be used4 is relatively low, e.g. within the range between 7.5 dg 10 kp/cm. This low pressure protects the sheet material, especially when it comes to chipboard, with low density, pg also enables the application of particularly thin surface protection layers, the structure of the underlying wood material does not appear so easily on the surface ("through telegraphs") at this low pressure. In this way, it is possible to.fr.emsti-lle no. layer-coated chipboards in a particularly cheap way. in the case, respectively, of plastic binders on the underlayer of wood, acts against the polyester resin layer, which forms the outermost surface of the product to be produced. : les, which héf témediates and prevents gout.... Rich-:-; lies in the possibility of a particularly fast processing and in the "good joining effect. -,. ;Furthermore, a surface is obtained which, due to its elasticity, and its fluidity during pressing, is closed and quite free of cracks, with the so-called graphite test, a very good result is obtained. The pre-impregnation of the carrier web is carried out in a known manner. The viscosity of the aminoplast and phenoplast impregnation resin solutions, as in has a solids content between 45 and 55%, is usually between 30 and 65 cp. A description of suitable aminoplastic impregnation resins can be found, for example, in the book by CP. Vale, Aminoplastics, London 1950. The reactivity of the impregnating resin solutions can be adjusted to the required or desired press speed by adding curing agents. Usually, the resin solution also contains wetting agents to improve the penetration of the paper, and additionally, for example, anti-foaming agents. The drying step inserted after the impregnation of the carrier material web is known in and of itself. As continuous coating methods are now usually used, the drying step is also carried out in a continuously operating plant, for example a suspended dryer. According to the invention, the pre-impregnated and dried carrier material web is now applied to the aforementioned mixture of non-crystallisable and crystallisable, sparingly soluble polyester. Preparations of this kind usually contain, in addition to the binder, cross-linking agents, catalysts and other additives. The preparations can be applied, for example, by casting, rolling, spraying, brushing or the like. The relevant work technique will be known to professionals and therefore need not be given an exhaustive description here. The quantities used may vary according to the circumstances; however, it usually involves amounts of polyester resin that are relatively small in relation to the aminoplastic or phenoplastic impregnation resin, and which only in rare cases reach the same order of magnitude. The amount of the polyester mixture can advantageously be 20-100% of the weight of the impregnation resin. This, in turn, is used in an amount of, for example, 50-180% of the paper weight. By adding metal oxides or metal hydroxides, such as magnesium oxide, calcium oxide and equivalent hydroxides, the polyester preparations can be thickened if necessary, possibly until almost adhesive-free gels are formed, which can be stored for a longer time without further change, and which can be cross-linked first during heating. By choosing suitable agents, however, a pre-crosslinking can also be provided by means of additives which trigger ionic polymerisation. It is not absolutely necessary that the polyester resin is applied in a solvent or a solvent mixture. However, for the production of adhesive-free, subsequently well-hardenable cover layers, it is often advantageous to add to the then reactive monomer, which normally makes up the bulk of the solvent, also a volatile solvent and remove this by a heat treatment after application. ;Preparation of various non-crystallizable polyester resin preparations (parts means parts by weight) a) 400 parts of a 60% acetone solution of an unsaturated polyester with a softening point (according to KSN) of 75-80°C, which was prepared from maleic acid , terephthalic acid dimethyl ester and propylene glycol-1,2 in the molar ratio 1:1:2 (acid number approx. 20), are mixed with 103 parts of a diallyl phthalate prepolymer and homogenized by stirring for 24 hours at room temperature. 6% tert-butyl peroctoate is added to the mixture. After a period of time, a precipitate separates, which can, however, be easily stirred up. 2.5% of a powdery, partially cross-linked polyester resin is added to the resin mixture while stirring. ;b) 80 parts of a 50% solution of diallyl phthalate prepolymer in monomeric diallyl phthalate and 400 parts of a 60% acetonic

solution of the unsaturated polyester described under a) is stirred at room temperature for 24 hours. A precipitate is obtained from this mixture (viscosity 56 DIN sec) after standing. 2.5% of a powdery, partially cross-linked polyester resin is added to the resin mixture while stirring.

Before coating the paper laminate, after adding 6% tert-butyl peroctoate, the mixture is vigorously shaken, whereby it becomes homogeneous.

c) The unsaturated polyester resin consists of a 60% styrenic solution of an unsaturated polyester of maleic acid, o-phthalic acid

and propylene glycol-1,2 in the molar ratio 2:1:3. This 0.01% hydroquinone stabilized resin (acid number approx. 33) is added with 6% tert-butyl peroctoate before the laminate coating.

d) 3000 parts of the unsaturated polyester resin described under c) are added at room temperature and with stirring 35.6 parts magnesium oxide and then kept at 55°C for such a long time that the homogeneous mixture, after cooling to 20°C, exhibits a viscosity of approx. . 109,000 cp; before coating, 6% tert-butyl peroctoate is added. Otherwise, the resins specified below are used;

Resin A is a 66% styrenic solution stabilized with 0.01% hydroquinone of an unsaturated polyester of maleic acid, o-phthalic acid and propylene glycol 1-1.2 in the molar ratio 2:1:3.15. Polyester's acid number is 50.

Resin B is a 65% styrenic solution stabilized with 0.01% hydroquinone of an unsaturated polyester of maleic acid and propylene glycol-1, 2 in the molar ratio 1:1. The resin has an acid value of 18.

Preparation of a crystallisable polyester resin

The crystallized unsaturated polyester contains fumaric acid, .. adipic acid and butanediol-1,4 in the molar ratio 4:1:5. It has an acid value of 20 and a melting point of 112°c (according to Kramer-Sarnow-Nagel) and is obtained analogously to the previous production methods.

Crystallite suspension (the polyester blend)

A crystallite suspension suitable for the production of reactive paper laminates can be prepared in the following way: A mixture stabilized with 0.135 part hydroquinone of

485 parts polyester resin A

650 parts polyester resin B

484 parts crystalline polyester and 380 parts styrene

is heated to 110°C with stirring under protective gas, after which the resulting solution is slowly cooled to room temperature. The white suspension has a viscosity of 1000 cp.

Composition of the thickenable coating mixture

100 parts crystallite suspension

1.5 parts MgO

1.25 part POCl3 solution (10% in dimethyl phthalate as thickening accelerator)

1.2 parts tert.-butyl perbenzoate (95%'s)

2.0 part calcium stearate

Drying time at 80°C: 2-3 minutes.

A lightly filled decorative paper with print, which was produced from a-cellulose and had a basis weight of 80 g/m 2 , is impregnated with an aqueous solution of a mixed condensate of urea, melamine and formaldehyde (resin absorption is approx. 90% of the paper weight). The residual moisture content, determined by a 5-minute post-drying at 160°C, is 5.6%. In another work step, the unsaturated polyester resin mixture described above is applied to the upper side. Harp coating out-o

makes 90 g/m .

The impregnated and coated paper is covered with a thermoplastic polyester film "Hostaphan" from Farbwerke Hoechst AG) and treated at 80°C in a hover dryer for 3 minutes, after which it is quickly brought to room temperature. The cover foil can be removed without damage, and the laminate is laid without an intermediate layer on a 19 mm thick chipboard with the polyester layer facing up.

It is then pressed in a so-called short stroke press for 120 seconds at 160°C under a pressure of 4 kp/cm<2>. The chipboard coated in this way is removed from the hot press without recooling. Already at this low pressure, surfaces are achieved which exhibit a high degree of gloss, and which are distinguished by their excellent sealing and crack resistance.

Claims (2)

1. Carrier material web that is impregnated and coated with hardenable synthetic resins, for surface treatment of wooden materials and consisting of a carrier material web that a) is impregnated in a manner known per se with a hardenable aminoplastic or phenoplastic impregnation resin and b) is provided on one side, with a coating of an unsaturated hardener bare polyester resin, characterized by the fact that the coating of unsaturated curable polyester resin consists of a solidified mixture of 20-98% of a non-crystallizable and 2-80% of a crystallizable polyester which, at room temperature, is difficult to dissolve in the usual monomers that act as cross-linkers, solidified by thickening through heating and which serves as a solvent, as well as possibly the usual crosslinking solvent media for unsaturated polyester resins. 2. Method e for the production of a carrier material web that is impregnated and coated with curable synthetic resins, for the surface treatment of wood materials, where the carrier material web is impregnated with a curable aminoplastic or phenoplastic impregnation resin, dried and on one side a coating of an exhausted, curable polyester resin is applied, characterized by applying a flowable mixture of 20-98% of a non-crystallizable and 2-80% of a crystallizable polyester L-:-o:ai at room temperature is poorly soluble in the usual monomers which have a cross-linking effect and which are used as solvents, and possibly the usual cross-linking-capable solvents for unsaturated polyester resins, which possibly also contain an inorganic thickening agent, and thicken when heated to 50-120°C with subsequent cooling.