WO1993015269A1 - Process for producing the surface of pieces of furniture or decoration - Google Patents

Abstract

A process is disclosed for producing the surface of door leaves, pieces of furniture or other pieces of furniture or decoration having a visible surface. A non-metallic coating layer is applied on the surface of a support core. A mash is produced at room temperature having 30 to 95 % by weight water, cellulose-containing fibres and a smaller proportion of synthetic thermoplastic fibres (containing polyester, polyvinyl alcohol, polyethylene, polypropylene, polyamide and/or their copolymers). The mash is enriched with light-fast filler, wet strength agents and binders, is pressed into a web of material which is then dryed in a first processing step then supplied to a second processing step, in which it is impregnated and again dryed. In a third processing step, the web of material is then surface-treated before being bound to the core. This surface may also be used for document files.

Description

Process for producing the surface of furnishing or equipment bodies

The invention relates to a method for producing the surface of door leaves, furniture or the like. - Furnishing or furnishing bodies offering a visible surface by applying a non-metallic cover layer to a supporting core.

Surfaces in the interior decoration industry, especially surfaces of door leaves, furniture or the like. Furnishing bodies are often provided with non-metallic layers made of polyvinyl chloride (PVC) and / or formaldehyde-containing substances. As is well known, valuable resources are used on the one hand in the production of PVC, since roughly 44% of the raw material consists of petroleum (56% rock salt), on the other hand, the energy requirement per ton of PVC is between 200 and 400 kWh plus the need for cooling water, Steam, water and the like

Emissions of dust, sulfur oxides, nitrogen oxides, hydrocarbons and carbon monoxide occur in the production of ethylene, and in particular sulfur dioxide and chloride emissions and dusts are released during electrolysis. In addition, asbestos, as part of the process-related sludge, must be deposited in hazardous waste landfills.

During the production of PVC - especially in the so-called Amalgam process, in which particularly pure sodium hydroxide solution is produced - mercury emissions arise which migrate into the products, the wastewater, the exhaust air and finally also to landfills. Chlorine, vinyl chloride and di-chloroethane emissions also occur. When processing PVC, about 5% to 10% of the energy expenditure is required for the production. In order to achieve certain properties of the articles, auxiliaries such as stabilizers, colorants, plasticizers, impact strength improvers, lubricants, fillers, flame retardants, antistatic agents, propellants or the like are used. used. For example, lead compounds are predominantly used for the stabilizers, but also tin, barium / cadmium, calcium / zinc stabilizers.

From the large number of emissions arising from the processing of the surface protection layer mentioned at the outset, only a few are listed below:

Vinyl chloride,

Hydrogen chloride,

Plasticizers,

Stabilizers,

Propellant,

Solvent,

Pigments dusts.

However, the disposal of PVC also creates problems, since the pollutant pollution is caused by the additives mentioned above. a. through chlorine, cadmium, lead, zinc and other heavy metals.

A recycling of PVC residues is only conceivable with their type purity in order to be able to produce recyclates by crushing. However, unmixed and clean PVC residues cannot be obtained from processed and used PVC sheets, so that they have to be incinerated, which in turn is not completely free of pollutant emissions. According to the inventor, the above-mentioned weighty disadvantages of the production, processing and disposal of parts made of polyvinyl chloride can be ruled out if a suitable material is available without the recognized disadvantageous properties. The aim of the invention is therefore to offer a low-pollutant product for the application area mentioned at the beginning, to reduce the use of irretrievable raw materials, to save energy and to largely prevent emissions. In addition, printability, a certain elasticity, tear resistance and washability of the surfaces should be made possible.

The teachings of the independent claims lead to the solution of this problem; the subclaims include particularly advantageous continuations.

According to the invention, completely new approaches are taken into consideration when producing carrier material with the properties of PVC film. Cellulose-containing fibers and a smaller proportion of these than synthetic thermoplastic fibers - which contain, for example, polyester, polyvinyl alcohol, polyethylene, polypropylene, polyamide and / or copolymers thereof - become a slurry with a water content of the order of 30 at room temperature up to 95% by weight, preferably about 95%, which is enriched with lightfast fillers, wet strength agents - such as resins - and binders and from which a material web is pressed; this material web thus produced from the slurry is dried and fed to a second process stage in which it is impregnated and dried again, after which it is surface-treated in a third process stage before it is connected to the core. In addition to long pulp fibers, mainly softwood pulps, synthetic thermoplastic fibers of greater fiber length and greater fiber strength are also used for the fiber area, and so-called linters (definition see Römpp, volume 3, 8th edition, p. 2376, or Temming, Linters, 1972, and Table 1 in the description below).

Staple fibers made of cellulose / viscose and synthetic thermoplastic fibers - such as polyamide, polyester, polyethylene, polypropylene, polyvinyl alcohol fibers or copolymers thereof, such as copolyamides - offer precisely defined fiber dimensions such as length and diameter with high strength of the individual fibers . These staple fibers must e.g. have a hydrophilic surface, i.e. they must be easy to disperse in water. In addition, no spinning and clumping (agglomerates) should occur.

In this context, it should be pointed out that the fiber lengths for the nonwoven fabric are limited upwards on a Fourdrinier wire and are between 4 to 12 mm with a fineness of 1.5 to 6.7 dtex. The use of longer fibers> 12 mm requires a different procedure for the formation of the fleece, e.g. B. the use of an inclined screen machine. The nonwoven advantageously contains about 10 to 40% by weight of synthetic fibers, 10 to 30% by weight of linters and the remainder cellulose.

The pulp fibers are fibrillated, for example, by grinding, i.e. the surface of the fiber is enlarged. This increases the number of OH bonds and thus the strength of the structure.

Fillers and optionally dyes (pigments) are introduced into the pulp, which must be lightfast and should not contain any scratching substances. These requirements improve the opacity and the impregnation ability. The light fastness values - measured according to the wool scale - should reach 6/7, around the decorative ones applied later Do not negatively influence surface prints and varnishes. The proportion of fillers and / or dyes in the finished film should be between 5 and 30%, depending on the color shade and weight per unit area, ie sufficient opacity must be achieved.

In order to maintain stability and flexibility with this special fiber structure, synthetic binders and possibly resins are added to the pulp. In addition, minerals can be added which not only cover, ie promote the desired opacity, but also increase the degree of whiteness.

Wet strength resins, for example MF resins, epichlorohydrin resins, can make the nonwoven fabric so wet-resistant that impregnation in the size press is possible without breaking the web. The resins improve e.g. the firmness.

For example, film-forming polymers - for example based on acrylates, styrenes, butadienes, polyurethanes or copolymers based on styrene-butadiene or polyvinyl acetate - are added as binders or binders. In particular, these must have a soft character and be good film-forming. Their use in bulk leads to better binding of the synthetic thermoplastic fibers to the cellulose fibers. In addition, the latex content is increased, i.e. the proportions of styrene-butadiene, acrylate, polyvinyl acetate and polyurethane or mixtures thereof. These binders soften the fleece and reduce the passage of air.

The pulp is then conveniently placed on a sieve. If, according to the invention, the web formation is generated there over several headboxes / sieves, then a composite is formed which results in a substantially better distribution of the fibers and fillers, in particular in the so-called Z direction. The impregnation ability as well as the tear and tear resistance are thereby positively influenced.

Now the train arrives with a water content of e.g. about 85% via a press section in a dryer group.

When drying, according to the invention, certain dry contents and temperatures are to be maintained, depending on the use of the fiber type, for example the following temperatures according to the invention

Polyethylene (PE):> 132 ° C; Polypropylene (PP): <163 ° C,

to melt the synthetic fibers; when melted, they combine with neighboring fibers and remain attached to them even after the temperature has dropped. When using certain fibers - especially synthetic fibers made from polyvinyl alcohol (PVAL) - it is necessary to have an absolute moisture of approx. 40 - 70% in the sheet when the fiber melting temperature is reached. It is only through the presence of moisture that the fiber gels and bonds with the surrounding fibers.

The described melting effects can be achieved through the interaction of these parameters, which significantly increase the strength values and the elasticity of the resulting material web of high splitting strength. According to the invention, this melting takes place before the impregnation process, but can also be carried out after this.

It is within the scope of the invention to guide the material web through an impregnation section, which can be done immediately after the drying process described above or later, before the web surface is treated. The impregnation takes place by means of plastic dispersions, rubber-like plastics or synthetic resins or with their mixtures. Care must be taken to ensure that the materials used for the impregnation have the softest possible, non-slip and thus film-like character.

All of the polymers which can be used here become more sticky with increasing softness of the film, and the shear stability of the dispersion decreases.

Above all, acrylates, melamines and melamine ureas are available. Their films are relatively lightfast and hardly tend to yellow, and there are different degrees of hardness.

Acrylic prepolymers are also used, which are applied with the above-mentioned applications and polymerized by means of electron bombardment. The structures of the acrylic polymers are similar:

CH2 = CH - CO - R - 0 - CO - CH = CH2, where R is an epoxy, polyester or polyurethane.

In addition to the circumstances already discussed when using copolymers, additions are also necessary in order to be able to influence certain properties of the impregnation liquor. These include, for example, means for adjusting the viscosity, increasing the shear strength and the like. the softer the selected polymers (acrylates etc.) become, the lower the desired splitting strength of the product produced.

The resins used here - for example based on melamine or urea - increase the splitting resistance.

The impregnation should preferably achieve a weight increase of at least 15% to 30% of the material web. The - more or less sticky - web coming from the impregnation section is dried on the surface, for example by means of high frequency, contactless electric shock drying or by electron bombardment. At the same time, the surface hardens.

The remaining drying up to 97% dry content, i.e. 3% residual moisture, takes place via contact drying.

The material or carrier web can be produced smooth on one side or also smooth on both sides on the production machine. In addition, further plasticization / compaction and surface smoothing can be achieved by means of hot satin coating.

The invention also encompasses the further step of subjecting the carrier material produced with a special fiber structure made of cellulose-containing fibers and synthetic thermoplastic fibers to a special impregnation and pretreatment (acrylates + resins + additive) in order to provide a surface which can be coated according to the invention to generate; the carrier web is now brought to a station in which the decorative surface by printing, embossing, painting, painting or the like. will be produced. There are several requirements to be met. In order to continue using the material web in the field of application mentioned, its rear side must be able to be glued - that is to say glued - while the top side must offer a hardened and resistant surface against scratching, mechanical influences and also weather resistance. These properties are advantageously designed from the recipe by using various coatings, lacquers and paints which can be crosslinked by means of electron beams. Subsequent electron beam radiation thus crosslinks the applied coatings and lacquers in such a way that their specific property profile is achieved, for example hardness, flexibility, softness, ductility, acid resistance, scratch resistance, lightfastness.

In the on-line process stage - that is to say the third stage - a liquid consisting of a printing ink and an emulsifying additive which changes the surface tension is expediently printed on the surface in a preselected pattern, then - at a preferred time interval of preferably less than ten seconds - a pigmented lacquer stroke, after which the material can be subjected to electron beam curing.

The additive used for the hydrophobization and stabilization of the surface is preferably a glycol siloxane copolymer which, in an aqueous gravure printing ink with a viscosity between 100 and 1100 cP (m. Pa's), contains organic and / or inorganic, heavy metal-free pigments , and possibly only small proportions of isopropanol - in a preferred amount of 8% by weight - is contained and generates a surface tension below 35 dynes / cm in the application areas or in the pattern. Since the latter is advantageously at least 10 dyne / cm less than that of the non-wetted areas, the applied lacquer layer will have "defects" or free zones in accordance with that pattern, ie the application of that liquid mixture of printing ink / additive, dried at about 120 °, ultimately determines the surfaces ¬ structure. Their visual impression is caused by different reflectance values of the areas opposite - in the incidence of light below 20%, in the other case above 30%. Through the treatment described, the surface of the flexible material web is cured accordingly and receives a resistant - e.g. B. scratch-resistant coating.

Fillers are used, for example, for increasing the opacity and hardness, pigments for producing the decorative character or for achieving better UV absorption and electrical conductivity. The pigments - organic or inorganic - must be non-toxic and should be easily compatible with the polymer system.

Thanks to these measures, a formdehdarm material web is created which, when measured, releases formaldehyde from the entire surface, i.e. from the front and back, by means of a gas analysis based on DIN 52 368 average values of 0.125 mg HCH0 / hm2 in hours 2 -4, the measured value of the first hour is disregarded in accordance with the standards. The generally applicable limit of 0.1 pp - as a result of the so-called Test chamber method in which the wood materials or furniture to be tested are exposed to specified conditions in a test chamber (DIN 55 666)

Average test room temperature 23 ° C + 1 ° C;

Mean relative humidity 45% ± 5%;

Average air change 1 change / hour + 10%;

Room load 1 m2 panel surface each

1 m3 (plate size depending on the plate type);

Installation of the plates with air around them on all sides

(0.3 m / s ± 0.1 m / s)

- corresponds approximately to the gas analysis result of 1.1 mg HCHO / hm2, which particularly illustrates the favorable distance of the product according to the invention from the limit value. Experiments have surprisingly shown that the above-described top layer as outer cover so-called stand folder - that of file folders, for example, the Mar ken Leitz 1050 or Leitz 1080 - is particularly durable and also helps to avoid the disadvantages of known top layers described there.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and from the drawing; this shows in

1: a sketchy process family tree;

FIG. 2: an oblique view of a detail from FIG. 1.

The inlet 10 of a production machine 12 for a flat web is preceded by silos 14 for cellulose fibers, silos 16 for synthetic fibers, and containers 18 or 20 for fillers or binders. The silo 14 is followed by a grinder 22 in the material flow. In the production machine 12, as already mentioned above, pulp fibers and a proportion of synthetic thermoplastic fibers - for example containing polyester, polyvinyl alcohol, polyethylene, polypropylene, polyamide or copolymers - are used of which - up to 40% by weight at room temperature produces a slurry with a water content of the order of about 95%, for example, which is enriched with lightfast fillers, wet strength agents - such as resins - and binders and formed a material web 24 under pressure from rollers (not shown) dried in a drying zone 26.

The synthetic thermoplastic fibers mentioned are those of greater fiber length and greater fiber strength. However, so-called linters, unspinnable short cotton fibers, such as the following specification, may also be used: -13-

TABLE

Analysis unit value method

Viscosity cP> 100 Temming method Cuoxam 1%

In the alternative embodiment of the production machine 12a, an integrated impregnation zone 28 is provided in front of the drying zone 26.

A mixture is formed during the impregnation

aqueous copoly dispersions, free of solvents and plasticizers;

nonionic surfactants as dispersants;

Water repellents in emulsion form;

low-formaldehyde resin registered and thermally hardened. As an alternative to the latter resin, acrylates can be used and then subjected to electron beam crosslinking. When impregnating, the web weight increases by 15 to 30%.

In the drying zone 26, not only is the material web 24 formed from that slurry-like mixture drying, but also its solidification; Amorphous fibers are melted under the influence of heat - for example by means of electric radiators which generate temperatures of 200 ° C. to 300 ° C., preferably 250 ° C. - so that the ductile mass then present can bond with the surrounding fibers - solidifies on cooling the fiber again, but its previously set adhesion is retained. This melting can be done before or after impregnation.

The material web 24 reaches - preferably in rolls 25 - a second station 30 of the plant for a surface treatment. The material web 24 is in a structuring zone

32 with a liquid mixture of printing ink - pigment silo

33 - and at least one additive - container 34 - printed in a pattern that has a lower surface tension than the other surface areas. The pressure fluid is dried in a drying zone 36 at about 120 ° and then provided with a lacquer coating on-line in station 38. The difference in surface tension produces different layer thicknesses in the My region. The lacquered material web 24s now passes into a device 40 for electron beam hardening of the lacquer. The following exemplary details in parts by weight apply to the described process: Printing ink

32% pig undispersion; 45% waste; 15% acrylic dispersion; 8% silicone oil;

Paint layer

42% pigment;

58% polyester acrylate;

as well as

Process parameters the following values:

Web speed:> 100 m / min. Coating viscosity: 500 mPas - 2000 mPas Coating quantity: 5 - 15 g / m2 Printing ink quantity: <2 g / m2.

The device 40 for a material web 24 with a width of approximately 2250 mm here has a hood-like yoke 44 with a cathode 45 and an anode 46 which is adjacent to the surface of the material web 24. A charge grid 48 is stretched between cathode 45 and ode 46. The surface moved in the direction of conveyance x - greatly exaggerated - material web 24 is passed in the area of the anode width by the electron beam generated in yoke 44, and a damage-resistant material web surface almost arises any structure.

This plant shows one of the possible process arrangements; Invention is not limited to this example. The following table shows a preferred embodiment of a product according to the invention using two examples.

B E L L E

Smoothness SS (sec) 40 218

Smooth OS Cobb 60 SS Cobb 60 OS

Bursting pressure (bar) 7.7 4.3 (garbage)

The basis weight is, for example, 195 or 100 g / m2.

Claims

PATENT CLAIMS 1. Method for producing the surface of door leaves furniture or the like. a device or equipment body offering a visible surface by surface application of a non-metallic cover layer on a supporting core, characterized, that a slurry with a water content of 30 to 95% by weight is produced at room temperature from cellulose-containing fibers and a lower proportion of these than synthetic thermoplastic fibers containing polyester, polyvinyl alcohol, polyethylene, polypropylene, polyamide and / or copolymers thereof and the slurry m lightfast fillers, wet strength agents and binders are enriched, pressed and a material web is produced that this material made from the slurry is dried in a first process stage and fed to a second process stage in which it is impregnated and dried again, after which it is used in a third Process step is surface treated before their connection with the core. 2. The method according to claim 1, characterized in that a slurry with a water content of 80 to 95 wt .-%, b preferably of about 95 wt .-%, is produced. 3. The method according to claim 1 or 2, characterized in that cellulose fibers, cell long fibers and / or unspinnable short cotton bevel are used in the fiber area as cellulose-containing fibers. 4. The method according to any one of claims 1 to 3, characterized ge indicates that as a binder film-forming polymers based on acrylates, styrenes, butadienes, polyurethanes or copolymers based on styrene-butadiene or polyvinyl acetate or mixtures thereof ein¬ be set. 5. The method according to any one of claims 1 to 4, characterized ge indicates that the different fibers are fed over several headboxes in different areas of the emerging material web. 6. The method according to any one of claims 1 to 5, characterized ge indicates that the material web is impregnated during drying in the first process stage and a change in the surface structure of the material web is generated in the second process stage. 7. The method according to claim 1 or 6, characterized in that the weight of the material web with the impregnation is increased by about 15 to 30%. 8. The method according to any one of claims 1 to 1, characterized ge indicates that the synthetic thermoplastic fibers contain amorphous fibers. 9. The method according to claim 8, characterized in that the amorphous fibers are melted in the material web before or after impregnation by supplying heat. 10. The method according to claim 8 or 9, characterized in that the synthetic thermoplastic fibers contain polyethylene or polypropylene and the fibers preferably contain amorphous fiber components or fibers and the amor¬ phen fiber components or fibers at 130 ° C to 170 ° C and be ¬ preferably amorphous polyethylene fibers at more than 132 ° C or a orphe polypropylene fibers are melted at less than 163 ° C ang. 11. The method according to at least one of claims 1 to 1, characterized in that the material web is treated in an integrated drying zone with non-contact Hochfr frequency, the drying preferably taking place surface area. 12. The method according to at least one of claims 1 to 1, characterized in that the material web is dried by electron bombardment. 13. The method according to at least one of claims 1 to 12, characterized in that the material web is surface-treated, wherein these coatings l are applied and crosslinked without solvent from acrylic prepolymers and / or monomers. 14. The method according to at least one of claims 1 to 13, characterized in that for structuring the material web on these silicone-containing additives must be applied, the surface tension of which is low than that of the remaining surface of the material web. 15. The method according to at least one of claims 1 to 1, characterized in that a silicone oil is applied to structure the upper surface of the material web. 16. The method according to claim 15, characterized in that the silicone oil contains siloxanes, preferably glycol siloxanes. 17. The method according to claim 15 or 16, characterized by a glycol siloxane copolymer. 18. The method according to any one of claims 14 to 17, characterized ge indicates that the surface tension-changing additive is emulsified in a printing ink, in particular an intaglio ink. 19. The method according to claim 18, characterized by an aqueous, heavy metal-free gravure printing ink containing organic and / or inorganic pigments. 20. The method according to any one of claims 14 to 19, characterized ge indicates that the surface tension of the pattern is set below 35 dynes / cm. 21. The method according to claim 14 or 20, characterized by a difference in the surface tensions of 8 to 12 dynes / cm, in particular about 10 dynes / cm. 22. The method according to any one of claims 14 to 21, marked by a proportion of the silicone oil in the printing ink of 5 to 10 wt .-%, preferably 8 wt .-%. 23. The method according to at least one of claims 14 to 22, characterized in that within 5 to 20 sec, preferably about 10 sec, after the structuring of the surface of the material web, the application of a lacquer layer is carried out inline. 24. The method according to at least one of claims 14 to 23, characterized in that the treatment of the material web surface is carried out with a printing ink having a viscosity of 100 to 1100 cP at 20 ° C and about 120 ° drying temperature. 25. The method according to any one of claims 13 to 24, characterized ge indicates that the material web for surface treatment is subjected to an electron beam hardening. 26. Use of the surface cover layer according to at least one of the preceding claims for the coating of door leaves, furniture or the like. furnishing or equipment bodies offering a visible surface. 27. Use of the surface cover layer according to at least one of claims 1 to 25 for the coating of equipment bodies offering a visible surface in the form of file folders.