ELLMANN JUERGEN (DE)
NIEDERSTADT RULE (DE)
ELLMANN JUERGEN (DE)
| WO1991001791A1 | 1991-02-21 |
| US5492733A | 1996-02-20 | |||
| US3650669A | 1972-03-21 | |||
| US5284902A | 1994-02-08 | |||
| US5110889A | 1992-05-05 | |||
| US4764395A | 1988-08-16 | |||
| US5108782A | 1992-04-28 | |||
| EP0109872A1 | 1984-05-30 | |||
| US6211308B1 | 2001-04-03 | |||
| GB1050362A |
MARSMAN M P W ET AL: "PIGMENTIERTE UV-HAERTENDE BESCHICHTUNGEN FUER TEXTILANWENDUNGEN", MELLIAND TEXTILBERICHTE, INTERNATIONAL TEXTILE REPORTS, MELLIAND TEXTILBERICHTE K.G. HEIDELBERG, DE, vol. 74, no. 5, 1 May 1993 (1993-05-01), pages 428,431 - 434, XP000364902, ISSN: 0341-0781
| 1. | A process for curtain coating of textile fabrics wherein a substantially horizontally moving web of a textile fabric has applied to it a substantially vertically freefalling curtain or a plurality of curtains in succession, each curtain consisting of a coating liquid, and wherein the textile fabric after the curtain or curtains have been applied is in a continuous operation exposed to irradiation by means of UV light or electron beams under such conditions that all curable compounds present in the coating liquid or liquids are fully cured on the textile fabric by polymerization, wherein the textile fabric may be dried after all coating liquids used have been applied, wherein at least one coating liquid contains one or more compounds of the formula (VI) or wherein at least one coating liquid contains oligomers or polymers of compounds of the formula (VI) which still contain at least one carboncarbon double bond, where R6 represents a radical of the formula (VIII) R represents H or CH3, a represents a number from 1 to 4, d represents a number from 3 to 25 and preferably from 7 to 19. |
| 2. | A process according to claim 1, characterized in that all coating liquids are substantially free of water and free of organic solvents. |
| 3. | A process according to claim 1 or 2, characterized in that the textile fabric is a woven or nonwoven consisting of polyester or polyamide fibers or of a blend of polyester fibers and cotton fibers. |
| 4. | A process according to one or more of claims 1 to 3, characterized in that the textile fabric is continuously led at a speed of 50 to 1000 m/min through a zone in which one or more coating liquids are each applied as a curtain and subsequently through a zone in which all curable compounds present in the coating liquid or liquids are cured on the textile fabric by polymerization by means of UV light or electron beams. |
| 5. | A process according to one or more of claims 1 to 4, characterized in that two or more coating liquids are applied in succession, at least one of the coating liquids used containing one or more compounds selected from compounds of the formulae (I) to (V) and of the formula (VII) CH2 = C (R)COOR' (') CH2 = C (R) 0R1 (II) or in that it contains oligomers or polymers of these compounds which still contain at least one carboncarbon double bond or at least one epoxy group, wherein the individual bracketed Si containing units in the formulae (III), (IV) and (VII) can have any distribution across the siloxane chain where R represents H or CH3, R'represents a branched or unbranched alkyl radical having 1 to 12 carbon atoms, R3 represents a monovalent radical formed from ethylene oxide by removal of a hydrogen atom, every R4 radical independently represents an alkyl radical having 1 to 4 carbon atoms, preferably CH3, or a phenyl radical every R5 radical independently represents R3 or R4 one of the R7 radicals represents a radical of the formula (IX) and the other R7 radicals independently represent R4 or a radical of the formula (IX), a represents a number from 1 to 4 b represents a number from 1 to 500 c represents a number from 1 to 20 e represents a number from 0 to 6 and preferably from 2 to 4. |
| 6. | A process according to one or more of claims 1 to 4, characterized in that at least one coating liquid contains a product formed by reaction of a hydroxyalkyl acrylate or methacrylate with a compound which contains one or more free isocyanate groups. |
| 7. | A process according to claim 5 or 6, characterized in that at least one coating liquid contains a reaction product as per claim 6 or an oligomer or polymer as per claim 5 and additionally a monomer as per one of the formulae (I), (II) or (V). |
| 8. | A process according to claim 7, characterized in that at least one coating liquid contains 100 to 250 parts by weight of monomers as per one of the formulae (I), (II) or (V) per 100 parts by weight of reaction product as per claim 6 or per 100 parts by weight of oligomer or polymer as per claim 5. |
| 9. | A process according to one or more of claims 1 to 4, characterized in that the textile fabric is a woven fabric and in that at least two coating liquids are applied to this woven fabric in succession, at least one applied coating liquid containing an oligomeric or polymeric siloxane which has one or more carboncarbon double bonds and/or one or more epoxy groups. |
| 10. | A process according to claim 9, characterized in that the oligomeric or polymeric siloxane has been mixed with a polymer other than this siloxane, preferably with a waterinsoluble polyurethane, polydimethylsiloxane or polyacrylate. |
| 11. | A process according to one or more of claims 1 to 5, characterized in that the textile fabric first has applied to it a first coating liquid which contains a compound as per formula (I) or (II) of claim 5 or a still curable oligomer or polymer of such a compound and in that there is subsequently applied a second coating liquid which contains a compound as per formula (VI) of claim 1 or which contains an oligomer or polymer of such a compound that still contains at least one carboncarbon double bond. |
| 12. | A process according to one or more of claims 1 to 11, characterized in that at least one coating liquid which contains one or more compounds having one or more carboncarbon double bonds and/or one or more compounds having one or more epoxy groups additionally contains a polymerization catalyst. |
It is known for textile fabrics such as for example wovens or nonwovens to be coated in order that the articles thus obtained be endowed with certain desired properties such as for example water repellency or abrasion resistance. The coating on the textiles frequently consists of polymers which form an uninterrupted film on the textile surface.
Useful known coating products include acrylate compounds. These can be applied to the textile material as polymers, in the form of a solution or dispersion, in which case the coated material subsequently has to be dried. Another well-known way to apply acrylate compounds is for curable or polymerizable monomers or oligomers to be applied to the textile material and subsequently cured by polymerization. This cure can be effected thermally or by irradiation.
Such processes are known for example from US 4 764 395 and US-B1 6 211 308.
US 5 146 531 and US 4 833 207 describe the coating of optical fibers with curable compounds followed by curing with UV radiation.
It is likewise known for products to be applied to sheetlike structures by curtain coating and subsequently, if appropriate, cured by polymerization. For instance, EP-A 704 285 describes a process for curtain coating wood panels, and WO-A 01/48 333 describes the formation of a decorative coating on a substrate. GB 1 050 362 discloses processes for curtain coating papery materials with polymer compositions, which are thus not subsequently cured. Lastly, US 5 110 889 describes the coating of substrates with curable compounds. Textiles and curtain coating are mentioned in passing, but pertinent process conditions are not mentioned.
The present invention has for its object to provide a process whereby textile fabrics are advantageously and economically coated to obtain coated fabrics which have advantageous properties, including good oil-and water-repellent properties, and whereby fabrics for a series of applications can be produced.
This object is achieved by a process for curtain coating of textile fabrics wherein a substantially horizontally moving web of a textile fabric has applied to it a substantially vertically free-falling curtain or a plurality of curtains in succession, each curtain consisting of a coating liquid, and wherein the textile fabric after the curtain or curtains have been applied is in a continuous operation exposed to irradiation by means of UV light or electron beams under such conditions
that all curable compounds present in the coating liquid or liquids are fully cured on the textile fabric by polymerization, wherein the textile fabric may be dried after all coating liquids used have been applied, wherein at least one coating liquid contains one or more compounds of the formula (VI) or wherein at least one coating liquid contains oligomers or polymers of compounds of the formula (VI) which still contain at least one carbon-carbon double bond, where R6 represents a radical of the formula (VIIl) R represents H or CH3, a represents a number from 1 to 4, d represents a number from 3 to 25 and preferably from 7 to 19.
Preferred embodiments of this process are claimed in subsidiary claims.
Advantages of the process according to the present invention include : a) Thinner layers can be applied to the textile material than in the case of conventional coating processes, which represents a cost saving. Yet the thinner layers provide effects which conventional coating processes only achieve at higher layer thicknesses. b) When a suitable apparatus is used, a plurality of layers, even those of different compositions, can be applied and fully cured/polymerized in a single operation. This can be accomplished when a suitable apparatus applies a plurality of curtains having appropriate coating liquids in succession in the direction of transport of the textile web. c) Not only relatively smooth but also rough fabrics can be coated to excellent effect. d) The rate of speed at which the web of the textile fabric is led through the coating and irradiation zone can be varied within wide limits without disadvantage.
e) The process according to the present invention makes it possible to produce coated textile fabrics having desired properties, for example with regard to water-and/or oil-repellent properties, abrasion resistance, dimensional stability.
The process according to the present invention involves coating a textile fabric and a subsequent curing/polymerization by irradiation.
Textile fabrics are in this context to be understood as meaning woven or nonwoven fabrics formed from fiber materials. The wovens can be textile wovens used for manufacturing clothing articles. But the term"textile fabrics"also comprehends wovens and nonwovens for industrial applications. Examples of articles which can be produced from wovens which have been treated by the process according to the present invention are weatherproof (water-resistant) clothing, home textiles, textiles for means of transport such as seat covers for automobiles and airplanes, tent canvas and tarpaulins. The textile fabrics used for the process of the present invention are preferably industrial textiles in the form of wovens or nonwovens.
The wovens or nonwovens used for the process preferably consist of polyester fibers, polyamide fibers or of a blend of polyester fibers and cotton fibers, for example in a 50: 50 blend ratio. But it is also possible to use woven fabrics composed of 100% cellulosic fibers, for example woven cotton fabrics.
The wovens may have a taffeta construction for example. Similarly, woven glass fiber fabrics can be treated according to the process of the present invention.
Nonwovens, which are advantageously coatable by the process of the present invention, preferably likewise consist of fibers composed of the abovementioned materials.
Any reference in the following to just one curtain or just one coating liquid is not to be understood as meaning that the process of the present invention is not capable of performing more than a single coating operation by means of a single curtain. On the contrary, the version whereby a plurality of curtains each having a coating liquid can be applied in succession is not ruled out thereby. This version will be described more particularly hereinbelow.
The process of the present invention is carried out using the textile fabrics in the form of wovens or nonwovens as substantially horizontally moving webs. A coating liquid is continuously applied to these webs. The coating liquid free-falls as a curtain (generated by a curtain coater) substantially vertically onto the moving textile web under the force of gravity.
The web of the textile sheet material normally has the temperature of the ambient atmosphere, i. e. , room temperature. It is preferably about 30 to 500 cm wide and 40 to 150 g/m2 in basis weight. The speed of the textile web is generally 30 to 1000 m/min and preferably between 100 and 600 m/min in the case of wovens and between 50 and 400 m/min in the case of nonwovens.
It was a surprise finding to the developers of the process according to the present invention that the high speeds mentioned, without which curtain coating technology would not make technical and economic sense, are achievable in the curtain coating of textile fabrics.
The curtain, which consists of the coating liquid described hereinbelow, is generated by a curtain coater and falls vertically onto the moving textile web. The curtain preferably has a temperature in the range between room temperature and 80°C. The curtain speed, i. e. , the amount of coating liquid applied to the moving textile web per unit time, depends inter alia on the rate of speed of the moving textile web and on the thickness desired for the coating layer on the textile web. The optimum curtain speed, i. e. , the optimum amount conveyed per unit time, is simple to ascertain through a few experiments for any given conditions.
The layer applied to the textile web is normally from 10 nm to 0.5 mm and preferably from 10 um to 100 um in thickness. These values relate to the sum total of the individual layer thicknesses in the case where a plurality of coating liquids were applied. Any one single layer, in contrast, may have a lower thickness, for example from 3 to 10 um, in the case where a plurality of layers were applied. The values mentioned relate to layers which contain substantially no water and no organic solvent and substantially no longer any curable compounds. If the coating liquid applied contains water and/or organic solvent, as is possible but not preferable, this water or organic solvent has to be removed again later, by drying for example. The removal of water or solvent can take place before, during or after the curing of the coating liquid or of the curable compounds present therein.
The abovementioned layer thickness values relate to water-and solvent-free textile fabrics which have already been treated with UV light or electron beams for the purpose of curing the coating.
Preferably, none of the coating liquids used contains water or organic solvent, apart from small amounts. This is commercially and environmentally beneficial and also has the additional benefit that there is no need to dry the textile web after coating. Such drying is necessary otherwise. The term"organic solvent"in this connection does not comprehend the products (monomers) as per one of the hereinbelow indicated formulae ()) to (VII) or oligomers or polymers thereof, i. e. , monomers as per one of the formulae (I), (II) or (V) which may be and preferably are included in the coating liquid for the purposes of viscosity control, as described hereinbelow.
If appropriate, however, one or more coating liquids may contain water or organic solvent, especially when the coating liquid would be excessively viscous without water or solvent.
The coating liquid preferably has a surface tension of less than 40 mN/m. Surface tension can be measured directly on the failing curtain by means of suitable commercially available instruments.
An important criterion in relation to the practice of the process according to the present invention is the dynamic viscosity of the coating liquid. An excessively high or excessively low viscosity gives rise to processing disruptions and/or disadvantages on the part of the coated textile fabric. This dynamic viscosity can be measured using known instruments, such as for example an RM 180 Rheomat from Mettler. All coating liquids used should have a dynamic viscosity in the range from 10 to 5000 mPa. sec at 20°C and preferably have a dynamic viscosity in the range from 10 to 1000 mPa. sec at 20°C. Dynamic viscosity is measured on the coating liquid before the latter is applied to the web of textile fabric, i. e. , on a sample of the coating liquid in a jar for example. As more particularly described hereinbelow, the dynamic viscosity of a coating liquid can be controlled and adjusted to specific values by addition of certain low molecular weight compounds.
The coating liquid, where it contains a plurality of ingredients, can normally be prepared by simply mixing individual ingredients together. The coating liquid should be a homogeneous liquid. Homogenization of the mixture of the individual ingredients may require well-known measures such as heating or vigorous stirring.
The process of the present invention is preferably carried out as a continuous operation which is characterized in that the textile fabric is continuously led at a speed of 50 to 1000 m/min through a zone in which one or more coating liquids are each applied as a curtain and subsequently through a zone in which all curable compounds present in the coating liquid or liquids are cured on the textile fabric by polymerization by means of UV light or electron beams. Passage through the coating zone may have to be followed by passage through a drying zone, when the coating liquid contains more than just insignificant amounts of water and/or organic solvent. However, this case does not constitute a preferred embodiment.
Suitable apparatus : Curtain coaters are well known, as are UV irradiators and electron beam irradiators.
Curtain coaters are available from Polytype SA, Fribourg, Switzerland. Polytype SA's product range includes apparatus wherein a curtain coater is combined or combinable with a radiative curer. Such combined apparatus makes it possible to conduct the process of the present invention in the form of a continuous operation, so that treatment of the textile fabric in such an apparatus directly provides a coated fabric on which the coating liquid used has already been cured/polymerized.
GB 1 050 362 describes suitable curtain coaters.
Suitable apparatus for irradiation by means of UV light or electron beams are mentioned in US 4 833 207 (see for example column 6 line 65 to column 7 line 18). Furthermore, apparatus for irradiating substrates by means of electron beams is available from RPC Industries, Hayward, Canada.
The conditions, especially the energy of the UV light or electron beams, under which the radiative curing/polymerization is carried out with the apparatus mentioned have to be chosen such that substantially all carbon-carbon double bonds and/or epoxy groups present in the coating liquid or liquids react to form polymers. The conditions under which this is achieved will be known to one skilled in the art and can be determined through a few experiments in any one particular case. Typically, for an electron beam treatment, the accelerator voltage used is in the range of about 100-200 kV and the irradiative intensity of the electron beams is about 10-40 kGy.
The wavelength range of the UV light is about 100-400 nm coupled with a UV lamp power output in the range from 80 to 300 W/cm.
Suitable curing conditions are also discernible from US-B1 6 211 308.
The zone in which the curing/polymerization by irradiation is carried out may be operated under an inert gas atmosphere, for example under an N2 atmosphere, if appropriate.
The coating liquids : These should be homogeneous liquids at the time and point of application. At least one coating liquid shall contain at least one compound of the hereinbelow recited formula (VI) It can also contain a plurality of such compounds. Furthermore, in lieu of a monomeric compound of the formula (VI) it may contain oligomers or polymers of such compounds. But these oligomers or polymers still have to contain at least one carbon-carbon double bond in order that curing by UV irradiation or electron beams may be possible.
When a plurality of coating liquids are employed, i. e. , when a plurality of products are curtain coated onto the textile fabric, one of these coating liquids will contain one or more compounds of the formula (VI) or, as mentioned above, curable oligomers or polymers thereof. Each of the other coating liquids may contain a compound having a carbon-carbon double bond and/or having an epoxy group which is polymerizable, i. e. fully curable, by application of UV light or of electron beams. It may also contain a plurality of such compounds. It may also contain one or more compounds which comprise not only one or more polymerizable carbon-carbon double bonds but also one or more polymerizable epoxy groups. In addition, one or more coating liquids may additionally comprise products having no polymerizable groups of the aforementioned kind. Examples thereof are polymers which contain perfluoroalkyl groups. When the process of the present invention is to be carried out such that a plurality of superposed layers are obtained on the textile fabric, it is necessary to employ curtain coaters capable of generating these layers, i. e. , apparatus whereby a plurality of curtains can be applied to the
moving textile web in succession. Each of these curtains consists of a coating liquid. The individual coating liquids will normally have mutually different chemical compositions. However, at least one thereof has to contain a polymerizable/curable compound of the aforementioned kind, i. e. , a compound of the formula (VI), or an oligomer or polymer thereof which still contains one or more polymerizable, curable carbon-carbon double bonds. The other coating liquids may likewise contain polymerizable/curable compounds but may also consist exclusively of nonpolymerizable products. However, all coating liquids used should meet the abovementioned requirements with regard to viscosity and surface tension.
Useful products for inclusion in an additionally employed coating liquid as containing at least one carbon-carbon double bond or at least one epoxy group include in principle all products having this property which either are known from the prior art of coating textile fabrics by conventional coating processes with subsequent radiative curing or form polymers on the textile after coating and radiative curing of the textile fabric which are already known as such, for example in the form of aqueous compositions, from the prior art for coating textile fabrics. The directions for further coating liquids employed in addition to those which contain a monomer as per formula (VI) or a curable oligomer or polymer thereof are as follows : Very useful ingredients for coating liquids as per the process of the present invention include acrylic esters and noncyclic organic compounds which contain one or more epoxy groups. It is particularly preferred for at least one of the coating liquids additionally used in the process of the present invention to contain one or more compounds selected from compounds of the formulae (I) to (V) and (Vil) CH2-C = C(R)-COOR1 (I) CH2 = C (R)-OR1 (II)
or in that it contains oligomers or polymers of these compounds which still contain at least one carbon-carbon double bond or at least one epoxy group, wherein the individual bracketed Si- containing units in the formulae (III), (IV) and (VII) can have any distribution across the siloxane chain where R represents H or CH3, R'represents a branched or unbranched alkyl radical having 1 to 12 carbon atoms, R3 represents a monovalent radical formed from ethylene oxide by removal of a hydrogen atom, every R4 radical independently represents an alkyl radical having 1 to 4 carbon atoms, preferably CH3, or a phenyl radical, every R5 radical independently represents R3 or R4, one of the R7 radicals represents a radical of the formula (IX)
and the other R7 radicals independently represent R4 or a radical of the formula (IX), a represents a number from 1 to 4 b represents a number from 1 to 500 c represents a number from 1 to 20 e represents a number from 0 to 6 and preferably from 2 to 4.
The compounds of the formulae (I) to (Vll) are commercially available or are reparable by methods known per se.
A further preferred embodiment of the process according to the present invention is characterized in that at least one of the coating liquids used contains a product formed by reaction of a hydroxyalkyl acrylate or methacrylate with a compound which contains one or more free isocyanate groups.
The compound mentioned, which contains one or more free isocyanate groups, can be an aliphatic, cycloaliphatic or aromatic mono-or di-or polyisocyanate. It can also be a polyurethane which still contains one or more free isocyanate groups and was prepared for example by reaction of a polyhydric alcohol with a polyfunctional isocyanate by using an excess of NCO groups compared with alcoholic OH groups.
The hydroxyalkyl acrylate or methacrylate mentioned is preferably a compound of the formula CH2= C (R)-COO-CHOH where R represents H or CH3 and a represents a number from 1 to 4 and preferably represents 2.
When such an acrylate is reacted with the isocyanate compound, alcoholic OH groups and NCO groups combine to form urethane bonds. This reaction is to be carried out such that the resultant product still contains polymerizable carbon-carbon double bonds. This product can serve as an ingredient in a coating liquid used in the process of the present invention. It can be a low molecular weight product having just one or a few urethane bonds or else a polyurethane of higher molecular weight that still contains at least one polymerizable carbon-carbon double bond.
When the polymerization/curing of the coating liquid is to be carried out using UV light, it is preferable for every coating liquid which contains a polymerizable carbon-carbon double bond and/or epoxy group to additionally contain a polymerization catalyst. This polymerization catalyst or photoinitiator causes the reactive groups mentioned to polymerize on application of UV light. When, in contrast, electron beam curing is to be employed, there is no need for such an initiator or catalyst.
Suitable UV photoinitiators will be known to one skilled in the art and are commercially available. Examples are products of the IRGACURE° range from Ciba Spezialitatenchemie AG, Basle, Switzerland, forexample IRGACURE° 184 and 819.
Further suitable photoinitiators are described in column 10 of the initially cited US-B1 6 211 308.
In a preferred embodiment of the process according to the present invention at least one of the coating liquids used contains a) a monomer as per one of the abovementioned formulae (I), (II) or (V) and additionally either b) an oligomer or polymer of a compound as per one of the formulae (I) to (V) wherein this oligomer or polymer still contains at least one irradiation-polymerizable carbon-carbon double bond or epoxy group or c) a product which, as described above, is formed by a reaction of a hydroxyalkyl (meth) acrylate with a compound which contains one or more isocyanate groups wherein this reaction product still contains at least one irradiation-polymerizable carbon-carbon double bond.
It is particularly favorable when the amounts of a) and b) or c) used here are chosen such that 100 to 250 parts by weight of a) are used per 100 parts by weight of b) or c). When a plurality of products of group a) or a plurality of products of group b) or a plurality of products of group c) are present in the coating liquid, the amounts belonging to the same group must be totted up for each group before the abovementioned proportions are calculated.
Acrylate compounds of the formula (I) or (II) are preferably chosen to represent products of group a) in this context.
The use of monomers of the formulae (I), (II) or (V) (group a) ) in addition to products of group b) or c) offers the advantage that in this case the dynamic viscosity of the coating liquid can be specifically adjusted to a value in the desired range if the viscosity would be too high for this coating liquid without the addition of product of group a).
A particularly advantageous embodiment of the process according to the present invention is characterized in that the textile fabric is a woven fabric and in that at least two coating liquids are applied to this woven fabric in succession, at least one applied coating liquid containing an oligomeric or polymeric siloxane which has one or more carbon-carbon double bonds and/or one or more epoxy groups.
The oligomeric or polymeric siloxane which is present in the coating liquid in this embodiment may be for example an oligomer or polymer of a compound as per one of the abovementioned formulae (III), (IV) or (VII) which still contains curable carbon-carbon double bonds or epoxy groups.
This version of the process according to the present invention makes it possible to use lower layer thicknesses of cured silicone than conventional coating/curing processes. Excellent wovens having layer thicknesses of 10 um to 20 urn with regard to cured siloxane can be obtained in this way.
A particularly favorable embodiment of the process described above is characterized in that the oligomeric or polymeric siloxane has been mixed with a polymer other than this siloxane, preferably with a water-insoluble polyurethane, polydimethylsiloxane or polyacrylate.
The additional use of a further polymer makes it possible to keep the amount of costly curable oligo-or polysiloxane at a lower level and thus achieve a cost advantage. The polymer other than the curable siloxane is preferably a nonpolymerizable, noncurable polymer such as for example a polyacrylic ester, polydimethylsiloxane or polyurethane.
This preferred version of the process according to the present invention is advantageously carried out with a homogeneous coating liquid by dispersing or dissolving the additional nonreactive polymer in the curable oligo-or polysiloxane. A homogeneous dispersion may be obtainable through use of a dispersant ; an example of a useful dispersant is «,-dihydroxy- polydimethylsiloxane.
The above-described version of the process according to the present invention is preferably carried out with a coating liquid containing 10 to 100 parts by weight of the additionally employed, nonreactive polymer per 100 parts by weight of curable oligo-or polysiloxane.
A further preferred embodiment of the process according to the present invention is characterized in that the textile fabric first has applied to it a first coating liquid which contains a compound as per formula (I) or (II) of claim 5 or a still curable oligomer or polymer of such a compound and in that there is subsequently applied a second coating liquid which contains a compound as per formula (VI) of claim 1 or which contains an oligomer or polymer of such a compound that still contains at least one carbon-carbon double bond.
This version of the process according to the present invention provides wovens which have good oil-and water-resistant properties and can be further processed into tent canvas or truck tarpaulins. This version of the process according to the present invention provides good oil-and water-resistant effects with thin layers of costly perfluoropolymers. The fluoropolymer being applied last means that there are a relatively large number of fluorine atoms at the surface of the article, so that thinner layers can be chosen. For instance, the thickness of the first layer
obtained after curing the first coating liquid applied is preferably about 20 to 40 um and the thickness of the second layer, which contains the fluorine compound, is about 2 to 8 um.
The first coating liquid applied in this version of the process according to the present invention contains a monomer as per the abovementioned formula (I) or (II) or an oligomer or polymer which is obtainable from monomers of the formula (I) or (II) and still contains polymerizable bonds. The second coating liquid, which is applied after the first coating liquid, contains a compound as per the abovementioned formula (VI) or an oligomer or polymer thereof, i. e. , a compound having perfluoroalkyl groups (R6). These compounds having perfluoroalkyl groups shall comprise curable or polymerizable bonds.
The process of the present invention will now be illustrated by operative example 1.
The individual tables which follow report values for the add-ons of coating products on the finished products (textile fabric after curing). These values were first calculated from the process parameters used and secondly determined gravimetrically. The values obtained by the two methods showed good agreement.
The result of the gravimetric determination in example 1 b is the sum total for the add-ons of the first and second layers.
Example 1 (inventive) 1a) Polyacrylate coating Example 1a) is as such not inventive, but demonstrates the application of a base layer by curtain coating. it is its combination with example 1 b, the subsequent application of a fluorinated acrylate, which constitutes the inventive example 1.
A radiation-curable aromatic urethane acrylate of comparatively high molecular weight (Ebecryl 210, UCB Chemicals) was mixed with a low molecular weight urethane monoacrylate (Ebecryl 1039, UCB Chemicals) in a stirred apparatus by stirring until homogeneous. The choice of a suitable composition enabled the properties of the coated finished products to be varied specifically. An amine-modified polyether acrylate (Ebecryl 84, UCB Chemicals) was additionally added to the above mixture in some cases for this purpose. To prevent the inclusion of air bubbles in the coating, the prepared mixtures were left to stand overnight to devolatilize. Table 1 gives an overview of the conducted coatings and coating conditions. All mixtures were applied to PES and PA taffeta (weight of uncoated fabric = about 80 g/m2) using a commercially available curtain coater from Polytype SA, Switzerland. Curing was accomplished by electron beam (intensity 20 kGy, accelerator voltage 150 kV) or by UV light (wavelength 100-400 nm, 120 W/cm) after addition of 0. 1% by weight of 2-hydroxy-2-methylpropiophenone (Darocur 1173, Ciba SC) to the coating liquid.
Table 1 Ebecryl Ebecryl Ebecryl Ebecryl Ebecryl 1039: 1039: 1039: 1039: 1039: Ebecryl 210 Ebecryl 210 Ebecryl 210 Ebecryl 210 : Ebecryl 210 : Ebecryl 84 Ebecryl 84 Component 70: 30 70: 30 25: 75 50: 25: 25 50: 25: 25 ratio [wt%] Curing Electron UV light Electron Electron Electron beam beam beam beam Curtain 25 25 65 25 25 temperature [°C] Viscosity of 320 320 1125 340 340 mixture at curtain temperature [mPas] Curtain 3.0 3.0 1.5 4. 2 3.0 volume flowrate [I/min] Web speed 250 150 150 150 250 of textile [m/min] Add-on 26 44 23 61 26 achieved in finished product (reckoned) [g/m2]
Example 1b Two-layer application Two-layer application, unlike the single-layer application described above and in example 2 below, involves coating with two different coating liquids or curtains through a multislot die. One die contains the coating liquid for the first layer (base layer) and the other die the coating liquid for the second layer (functional layer, top coat). A polyacrylate coating similar to example 1 a was chosen for the base layer. The coating in question consisted of a mixture of a radiation- curable aromatic urethane acrylate (Ebecryl 210, UCB Chemicals) with a urethane monoacrylate (Ebecryl 1039, UCB Chemicals) and an aliphatic urethane acrylate of comparatively high molecular weight (Ebecryl 230, UCB Chemicals) or a glyceryl acrylate (OTA 480, UCB Chemicals) with an aliphatic urethane acrylate (Ebecryl 230, UCB Chemicals) and an amine-modified polyether acrylate (Ebecryl 84, UCB Chemicals). To obtain an oil-and water- resistant coating, the coating liquid chosen for the top coat was a mixture containing fiuorinated acrylates (Zonyl TAN, DuPont). This mixture was mixed with OTA 480 and Ebecryl 230 for improved processing. Table 3 shows an overview of the conducted coatings. Curing was carried out by electron beam similarly to the conditions chosen in example 1 a.
Table 3 First layer (base layer) Ebecryl Ebecryl OTA 480: OTA 480: 1039: 1039: Ebecryl Ebecryl Ebecryl Ebecryl 210: 210: 210: 210: Ebecryl 84 Ebecryl 84 Ebecryl Ebecryl 230 230 Component ratio 60: 20 : 20 60: 20: 20 60: 32 : 8 60: 32: 8 wt% Second layer (functional layer, top Zonyl TAN : Zonyl TAN: Zonyl TAN : Zonyl TAN: coat) Ebecryl Ebecryl Ebecryl Ebecryl 230: 230: 230: 230: OTA 480 OTA 480 OTA 480 OTA 480 Component ratio 37: 13: 50 37: 13: 50 25: 15: 60 25: 15: 60 [wt%] Curing Electron Electron Electron Electron beam beam beam beam Curtain temperature [°C] 35 35 35 35 Viscosity of mixture at curtain 300 300 550 550 temperature, first layer [mPas] Viscosity of mixture at curtain 140 140 180 180 temperature, second layer [mPas] First layer curtain volume (flowrate) 2.9 3.9 2.5 3.4 [I/min] Second layer curtain volume (flowrate) 0.9 0.9 0.9 0.9 [)/min] Web speed of textile [m/min] 220 330 220 330 Add-on achieved for first layer 29 26 25 23 (reckoned) [g/m2l Add-on achieved for second layer 8 5 8 6 (reckoned) [g/m21
Example 2 Silicone coating This example is outside the present invention. It shows how a curable polysiloxane can be curtain coated onto polyamide in a first step. An inventive example would only result on additionally applying a product of the formula (VI) or a curable oligomer or polymer thereof in a continuous manner.
An acrylic-modified radiation-curable polysiloxane (Tego RC 902, Degussa, Germany) was curtain coated onto PA taffeta (weight of uncoated fabric = about 80 g/m2). Curing was carried out by electron beam under the conditions described in example 1 a. Table 2 gives an overview of the conducted coatings. Adhesion to the textile was improved by adding 30% by weight of an acrylic-modified radiation-curable polysiloxane (Tego RC 711 Degussa, Germany) as an adhesion promoter to the coating liquid in one run. In a further run, the radiation-curable Tego RC 902 silicone was combined with an unreactive polydimethylsiloxane (PDMS). Full, complete curing of the curable compounds in the individual systems was achieved in all cases.
Table 2 Tego RC Tego RC Tego RC Tego RC 902 902 902: 902: Tego RC PDMS 711 Component ratio [wt% l 100 100 70 : 30 50: 50 Curing Electron Electron Electron Electron beam beam beam beam Curtain temperature [°C] 25 25 25 25 Viscosity of mixture at curtain 460 460 460 temperature [mPas] Curtain volume (flowrate) [I/min] 1.5 1.5 1.5 1.5 Web speed of textile [m/min] 150 300 150 150 Add-on achieved in finished product 20 10 20 20 (reckoned) [g/m2] The low add-ons achieved cannot be achieved when the coating products mentioned are employed in conventional textile-coating processes.
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