WO2016102520A1 - Revêtements réduisant la pollution - Google Patents

Revêtements réduisant la pollution Download PDF

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Publication number
WO2016102520A1
WO2016102520A1 PCT/EP2015/080893 EP2015080893W WO2016102520A1 WO 2016102520 A1 WO2016102520 A1 WO 2016102520A1 EP 2015080893 W EP2015080893 W EP 2015080893W WO 2016102520 A1 WO2016102520 A1 WO 2016102520A1
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WIPO (PCT)
Prior art keywords
binder
composition
metal substrate
coated metal
titanium dioxide
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PCT/EP2015/080893
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English (en)
Inventor
Chris Lowe
James MAXTED
Chandrakant MISTRY
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Becker Industrial Coatings Limited
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Publication of WO2016102520A1 publication Critical patent/WO2016102520A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/39—Photocatalytic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B01J37/0219—Coating the coating containing organic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B01J37/0225—Coating of metal substrates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2237—Oxides; Hydroxides of metals of titanium
    • C08K2003/2241—Titanium dioxide

Definitions

  • the present invention relates to pre-coated metal sheets that have NO x abatement activity and to coatings and compositions that have NO x abatement activity.
  • the invention further relates to kits comprising two compositions for mixing to provide NO x abatement coatings.
  • the invention one component systems for applying coatings to a substrate in a factory or similar and two component systems for mixing at the site of application to provide ⁇ abatement coatings. Background
  • catalytic converters can be used on vehicles to encourage the reduction of oxides of nitrogen and the oxidation of CO and unburnt hydrocarbons.
  • catalytic converters are not always an effective solution, not least because engines, especially diesel engines, are running hotter which results in more NO x in the exhaust and less hydrocarbon.
  • European cities, such as London have unacceptable levels of NO x and are being prosecuted by the EU Commission in an attempt to force the authorities into action.
  • Titanium dioxide is widely used as a pigment in paints and coatings.
  • the photo-catalytic effect of titanium dioxide has been known for many years. It is common knowledge that if the titanium dioxide pigment particles are not encapsulated by silica and other inorganic oxides such as alumina or zirconia, then the particles will initiate photo-degradation reactions in the organic coatings into which they are incorporated. This results in undesirable
  • Encapsulation of the titanium dioxide particles isolates most of the titanium dioxide surface, which reduces the photo-catalytic activity to acceptable levels.
  • Pre-coated metal is often a material of choice used by the construction industry, especially when the building being assembled is similar to a warehouse or factory and so a large area needs to be protected from the elements.
  • the substrate is often galvanised steel coated with a paint system that is applied under factory conditions for consistent quality.
  • aluminium and steels coated with different metallic coatings for example, Galfan and Galvalume can be used also as substrates.
  • thermosetting polymers such as polyesters cross-linked with hexa-methoxymethyl melamines, although polyesters cross-linked with isocyanates are also used.
  • Thermoplastic coatings can be used and these are normally based on either plasticised polyvinyl chloride or poly vinylidene difluoride alloyed with an acrylic resin or fluoro-polymers consisting of alternating fluoro-ethylene and alkyl vinyl ether segments. Pigments are added to give colour and sometimes functionalities such as near infrared (NIR) reflectivity.
  • NIR near infrared
  • the present invention is based on the inventors' insight that a single coating having both ⁇ abatement properties and good resistance to degradation would be desirable in terms of cost of production of pre-coated materials, environmental impact (less waste, both of energy and scrap metal) and manufacturing ease and efficiency.
  • the invention further provides kits comprising compositions that may be mixed at the point of use to enable NO x abatement coatings to be applied to substrates by, for example, brush or spray application.
  • the invention further provides two component systems.
  • the present invention provides this by using binders that are somewhat resistant to the degradation chemistry associated with photoactive titanium. The inventors have observed that after an initial degradation of the organic binder reveals the naked titanium dioxide particle the film remains intact for a considerable period of time.
  • Embodiments of the present invention provide coatings that reduce NO x levels and have durability ratings that meet the Ruv2 classification (EN10169-2). This durability makes the materials and compositions described herein suitable for coating coil for the construction industry and / or for applying to surfaces by brush or spray application either during construction or later as a maintenance or repair application.
  • the present invention provides a coated metal substrate wherein the coating comprises a NO x active material, the NO x active material comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the silicone content of the binder is at least 30%wt of the solids in the binder.
  • the present invention further provides a coated metal substrate wherein the coating comprises a NO x active material, the NO x active material comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the material has a NO x abatement value of 5% or more, more preferably 10% or more (measured as described herein) after 1000 h of cycling 4 h UV exposure, 4 h condensation (EN 13523-10 specification).
  • the coating comprises a NO x active material, the NO x active material comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the material has a NO x abatement value of 5% or more, more preferably 10% or more (measured as described herein) after 1000 h of cycling 4 h UV exposure, 4 h condensation (EN 13523-10 specification).
  • the present invention further provides a coated metal substrate wherein the coating comprises a NO x active material, the NO x active material comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the material is formed from a composition comprising at least 5%wt silicone of the total weight of the composition (prior to application and drying to form the coating), more preferably at least 7%wt, more preferably at least 10%wt.
  • the silicone content of the composition prior to application and drying may be 7-15%wt, for example, 9-13%wt.
  • the present invention further provides compositions for application to substrates. These compositions, when dried, form NO x active material, for example, coatings.
  • the NO x active coatings have a NO x abatement value of >5%, more preferably, greater than 10% (measured as described herein) after 1000 h of cycling 4 h UV exposure, 4 h condensation (EN-13523-10 specification).
  • the present invention provides a composition for applying to a substrate to form a NO x active coating, the composition comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the silicone content of the binder is at least 30%wt of the solids in the binder.
  • the present invention further provides a composition for applying to a substrate to form a ⁇ active coating, the composition comprising a binder comprising a silicone and a polymer, wherein the material is formed from a composition comprising at least 5%wt silicone of the total weight of the composition (prior to application and drying to form the coating), more preferably at least 7%wt, more preferably at least 10%wt.
  • the silicone content of the composition prior to application and drying may be 7-15%wt, for example, 9-13%wt.
  • Liquid compositions according to the present invention may be provided as "one pot” (1 K) or “two pot” (2K) systems.
  • the two pot system may be provided as a kit comprising a composition comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the silicone content of the binder is at least 30%wt of the solids in the binder (the first pot); and a hardener (the second pot).
  • the hardener is a cross-linker which may be provided in a solvent.
  • the present invention further provides a kit including:
  • composition comprising photoactive titanium dioxide and a binder, the binder comprising a silicone and a polymer, wherein the silicone content of the binder is at least 30%wt of the solids in the binder;
  • a hardener composition comprising a cross-linker in a solvent, optionally wherein the cross linker is an unblocked isocyanate.
  • compositions (i) and (ii) are provided in separately sealed containers (which may also be described as pots), optionally within instructions for a method as described herein.
  • the containers may be supplied unsealed, for example, in pails.
  • the kit may include an applicator, for example, a spray gun or a brush.
  • the following optional features and preferences apply to NO x active materials and compositions for applying to a substrate to form a NO x active coating, except where context dictates otherwise.
  • the ⁇ active materials of the invention may comprise a pigment, for example, pigmentary titanium dioxide.
  • the compositions of the invention may further comprise a pigment such as pigmentary titanium dioxide. Other pigments are of course envisaged.
  • suitable pigments may be selected to afford the desired colour and durability.
  • the binder may comprise a silicone and a polyester.
  • the binder does not significantly absorb UV light > 300 nm wavelength. More preferably, the binder does not significantly absorb UV light > 290 nm wavelength. Without wishing to be bound by any particular theory, the present inventors believe that low or no absorbance at these wavelengths increases the durability of the coating.
  • the binder comprises a polyester formed from a diacid component in which the two acid moieties are not in electronic conjugation. It will be appreciated that binders may be formed using more than one diacid and / or more than one polyol. In some embodiments, the binder comprises only one diacid and only one polyol.
  • the binder may comprise a polyester formed of isophthalic acid and a polyol.
  • the binder may comprise a polyester formed of hexahydrophthalic anhydride and a polyol.
  • the polyol is trimethylolpropane.
  • the coated metal substrate of the invention may have one, two, three, or even more layers. To improve cost efficiency, it may be preferable to use only one or two layers.
  • the coated metal substrate of the invention has two layers, for example, a primer and the ⁇ active material, wherein the NO x active material is applied directed to the primer.
  • the NO x active material forms a topcoat.
  • the present inventors have found that the NO x activity and / or durability of the coatings is often improved with increased surface area and / or more uniform particle size of the photoactive titanium dioxide. Accordingly, in some preferred embodiments, the photoactive titanium dioxide is micronized.
  • the present inventors have found that it may be advantageous to pre-treat the binder to effect reaction of the silicone and the polymer.
  • the silicone and polymer (for example, polyester) of the binder may be heated or otherwise treated to effect covalent bond formation between the two.
  • the binder is silicon and polyester at least partially bound together by covalent bonds.
  • the present invention further provides coatings formed using compositions of the invention.
  • compositions of the invention are suitably applied to metal substrates either as a topcoat on a suitable primer or as a single coat by continuous coil coating and / or other suitable application methods including, but not restricted to, spray application, electrostatic spray application, powder coating application and brush application.
  • the present invention further relates to methods of manufacturing a substrate having a NO x active coating applied as described. Accordingly, in a further aspect the present invention may provide a method of
  • a primer coating to a surface of the substrate to form a primer coat
  • the step of providing the composition may comprising mixing compositions (i) and (ii) to provide a composition for applying to a substrate.
  • the composition that is applied may be a one pot composition (for cross-linking at high temperatures, for example on a coil line), or a two pot composition that has been mixed and cross-links under ambient conditions.
  • the substrate is sheet metal as described herein.
  • the method may be a method of manufacturing coil.
  • the coated metal substrate is a coated metal coil.
  • the application of the composition to the metal substrate or primer coat on the metal substrate may therefore use a roll coating process. Typical roll coating processes are known in the art in the field of metal coil manufacture.
  • the present invention also provides coated metal substrates manufactured by methods as described herein.
  • Coated metal substrates of the invention may be used in the construction industry to assist pollution control. Accordingly, in a further aspect the present invention provides use of a coated metal substrate of the invention in the abatement of NO x .
  • Coated metal substrates of the invention may be used near roads or railway lines to assist pollution control.
  • the coated metal substrates of the invention may be located in tunnels.
  • the tunnels may be vehicular and/or rail tunnels.
  • the coated metal substrates of the invention may also be used in other suitable locations.
  • they may be used to line walls alongside roads or railway lines.
  • they may be provided as panels, or a component of panels, provided near roads or railway lines. Definitions
  • ⁇ refers to oxides of nitrogen, also referred to a nitrogen oxides, that may be common pollutants in exhaust fumes.
  • x is 1 or 2; that is, NO x may refer to nitric oxide (NO) and nitrogen dioxide (N0 2 ) and mixtures thereof. Unless stated otherwise, NO x refers to the total concentration of NO and N0 2 in the atmosphere surrounding the coating.
  • this term refers to a material that has NO x abatement activity. In other words, to a material that reduces the total amount of NO x gases in the atmosphere surrounding the surface of the material.
  • the materials described herein are suitably coatings formed by application of compositions that are then dried. Throughout this application, references to coatings apply generally to NO x active materials of the present invention. Suitable compositions are described herein, and the invention relates to both materials (i.e. after application and drying) and compositions (liquid formulations including solvent prior to application and drying).
  • the NO x active material is a coating on a substrate, for examples, a metal substrate.
  • suitable metal substrates include Hot Dip Galvanised Steel, Galfan ® , Galvalume ® , Zinc aluminium magnesium alloy metal coatings as well as aluminium and cold rolled steel. These coated substrates may be provided as coils.
  • the N0 X active material is provided as the uppermost coat (topcoat). It may be the only coat, or may be used in association with further coats.
  • a primer coat may be provided.
  • a surface of the substrate is coated with a primer and a NO x active topcoat.
  • coil refers a pre-coated metal substrate produced on a coil coating line using a coil coating process, for example as described as follows.
  • Coil coating is a continuous, automated process for coating metal before fabrication into end products.
  • the substrate typically steel or aluminum, is delivered in coil form from the rolling mills.
  • the metal coil is positioned at the beginning of the coating line, and in one continuous process, the coil is unwound, cleaned, pre-treated, primed, and/or painted (as appropriate); it is then re-coiled at the end of the line. These rolled coils are then supplied ready for cutting and shaping to the construction industry.
  • the coils of the present invention are "two coat" coils. These two coat coils comprise a 1 st coat which is a primer and a 2 nd coat which is a top coat. In coils of the present invention, this 2 nd coat is a NO x active topcoat.
  • the primer cost is a 1 st coat which is a primer and a 2 nd coat which is a top coat. In coils of the present invention, this 2 nd coat is a NO x active topcoat.
  • the primer cost is a 1 st coat which is a primer and a 2 nd coat which is a top coat.
  • a backing coat can be applied to the reverse side of the strip to suit the intended end use.
  • the provision of a NO x active top coat that may be applied directly to the primer reduces the number of runs needed to produce the coil as compared to conventional three coat systems.
  • photoactive Ti0 2 also referred to herein as photoactive Ti0 2 , PA Ti0 2 and PA.
  • This refers to ultrafine titanium dioxide having high surface area and high purity.
  • the photoactive titanium dioxide is predominantly anatase titanium dioxide.
  • more than 75% by weight of the total Ti0 2 may be in the anatase form.
  • the Ti0 2 content of the powder is greater than 80%wt, for example ⁇ 85%wt or around ⁇ 95%wt.
  • the surface area is at least 20 m 2 /g, preferably at least 50 m 2 /gm, more preferably at least 70 m 2 /g, most preferably at least 90 m 2 /g, as measured by the 5 point BET method.
  • the surface area is at least 100 m 2 /g, for example at least 150 m 2 /g or even greater, for example, at least 200 m 2 /g, at least 250 m 2 /g, or even at least 300 m 2 /g.
  • the photoactive titanium dioxide has a particle size of less than 150 nm, preferably less than 50 nm, for example 5-50 nm, 5-40 nm, 5-30 nm, 5-25 nm, or even 5-20 nm.
  • the photoactive titanium dioxide may be micronized. In these cases, the particle size may be 15 nm or less, for example, 5-15 nm or even 5-10 nm.
  • references to particle size will be understood to mean the average particle size of the titanium dioxide particulates.
  • the particle sizes may be measured by suitable methods apparent to those skilled in the art, and it will be understood that the above values should be read to embrace proximal values that may be attributed to experimental error.
  • the particle sizes may be measured by, for example, transmission electron microscopy (TEM) or X-ray diffraction (XRD).
  • TEM transmission electron microscopy
  • XRD X-ray diffraction
  • Suitable photoactive titanium dioxide commercially available includes CristalACTIVTMPC500, CristalACTIVTMPC105, CristalACTIVTMPC105M (micronized), and PCX4 (all available from Cristal).
  • the photoactive titanium dioxide is present in coatings and compositions of the invention. Owing to the cost of photoactive titanium dioxide, preferably the amount is equal to or less than 1 1 %wt of the total formulation.
  • photoactive titanium dioxide may be present in coatings and compositions of the invention in an amount from 1 -1 1 %wt, for example, 3-1 1 %wt, preferably 3-8wt%. The preferred amount may vary with the exact nature of the composition and its intended use.
  • compositions applied on a coil coating line are preferably, 5-8%wt, most preferably around 7.5%wt.
  • the amount is preferably lower; around 3-5%wt, for example around 4%wt.
  • the numbers given are %wt of the composition and prior to application and drying to form the coating.
  • pigmentary Ti0 2 This refers to titanium dioxide pigment, as may be included in, for example, coil coatings, protective coatings, powder coating, automotive, OEM and refinishing systems.
  • the pigmentary titanium dioxide is rutile titanium dioxide, for example, chloride process rutile titanium dioxide.
  • Pigmentary titanium dioxide may have a larger average particle size than photoactive titanium dioxide. For example, the average particle size may be about 0.2 to 0.35 microns.
  • Commercially available pigmentary titanium dioxide suitable for use in the present invention includes TiONA ® 696 (available from Cristal) and Ti-Pure R-960 ® (available from DuPont ® ).
  • the NO x active coatings and compositions of the invention include pigmentary titanium dioxide.
  • the pigmentary titanium dioxide content of the NO x active coatings and compositions of the invention may be 0-50%wt, preferably 5-50%wt, more preferably 5-40%wt, more preferably 10-40%wt, more preferably 20-40%wt, more preferably 25-40%, more preferably 30-40%, most preferably 35-37%wt.
  • the numbers given are %wt of the composition and prior to application and drying to form the coating.
  • pigments may be in addition to pigmentary titanium dioxide.
  • no pigmentary titanium dioxide may be present, and only one or more other pigments provided.
  • Suitable pigments are known in the art and may include iron oxide reds, yellows and blacks.
  • Other suitable pigments may be modified titanium dioxide, for example, spinel titanates in which ⁇ 02 has been modified with other elements such as nickel and antimony.
  • the pigment to binder ratio may be in the range 1 :1 to 1 .5:1 , preferably 1 .3:1 to 1 .4:1 .
  • the coatings and compositions of the invention comprise a binder.
  • the binder comprises a silicone and a polymer.
  • the polymer is an organic polymer; in other words, it has a carbon-containing backbone.
  • the polymer is a polyester, as described herein, although it will be appreciated that other polymers may be used, for examples, acrylates and methacrylates.
  • the binder comprises only silicone and polymer.
  • the binder may include a solvent. Suitable solvents are known in the art. This facilitates manufacture and application of the compositions to the substrates.
  • references to the binder herein refer to solids in the binder.
  • dried materials (coatings) formed from the compositions described herein are substantially free of solvent, that is, the binder in the coatings described herein may comprise only solids. It follows that for such substantially solvent-free materials (coatings), references to solids in the binder refer to the binder.
  • Suitable silicone-modified saturated polyesters include Benester SL compositions
  • the present inventors speculate (without wishing to be bound to any particular theory) that comparatively high silicone content contributes to the desirable durability profile for the NO x active coats and compositions of the present invention.
  • the binder comprises at least 30%wt silicone, preferably at least 35%wt silicone, more preferably, at least 40%wt silicone, more preferably at least 45%wt, more preferably at least 50%wt.
  • the silicone content of the binder may be less than 80%wt, for example less than 70%, for example less than 60%
  • the silicone is provided in combination with a polymer, preferably a polyester, in the binder.
  • the binder comprises at least 30% polymer. These percentages refer to % by weight in the binder. Any solvent provided is not, for the ratios and %wt values given herein, considered a part of the binder.
  • the binder in the composition, or composition prior to application and drying to form the material may comprise silicone and polymer in a ratio between 3:7 and 7:3.
  • the binder comprises silicone and polymer in a ratio of between 1 :1 and 7:3, for example between 7:6 and 5:3, for example, between 4:3 and 5:4.
  • the binder comprises silicone and polymer in a ratio of around 6:4.
  • the binder may comprise the silicone as an oil; that is, the binder may be a blend of silicone oil and polymer.
  • pre-treat the binder so as to pre-react the silicone and the polymer, for example, to cause reaction between the silicone and the hydroxyl groups on the polymer (in the case of a polyester or similar) to form covalent bonds.
  • This pre-treatment step may comprise a heating step.
  • the polymer may be thinned in a suitable solvent (i.e. one that will provide compatibility without interrupting the course of the reaction) and the silicone adding during heating.
  • a suitable solvent is 1 -methoxy-2-propyl acetate.
  • This solvent component is, for the ratios and %wt values given herein, not considered a part of the binder.
  • a catalyst for example, a titanate is added.
  • the catalyst may be added at 0.01 to 0.1 %wt of the total monomers.
  • This catalyst is, for the ratios and %wt values given herein, not considered a part of the binder.
  • any solvent added to thin the polymer is not considered a part of the binder. Rather, this solvent is considered part of the solvent content of the formulations.
  • the heating step is at a temperature above 100 °C, for example, around 140 °C until viscosity and non-volatile requirements are met.
  • Silicones are polymeric structures made up of repeating units of siloxane.
  • the silicones described herein are mixed inorganic-organic polymers in which silicon atoms bear organic R substituents, where each R is an organic group such as methyl or phenyl. They may also be referred to as polymerized siloxanes or polysiloxanes.
  • the silicone of the binders described herein comprises both methyl and phenyl groups.
  • the ratio of phenyl to methyl groups is in the range 0.5:1 to 1 :1 , for example 0.6:1 , 0.7:1 , 0.8:1 or 0.9:1 . Preferably, it is about 1 :1.
  • Higher methyl group content formulations are cheaper and react faster, but the inclusion phenyl groups in the ratios specified aids handling and / or mechanical properties of the end product (high methyl content leads to hard resins). Appropriate selection for the desired cost performance relationships are within the remit of the skilled person.
  • the silicone content in the compositions and NO x active material described is at least 5%wt of the total weight of the composition prior to application and drying to form the material, more preferably at least 7%wt, more preferably at least 10%wt.
  • it may be 7-15%wt, for example, 9-13%wt.
  • polyester refers generally to any and all polymers that contain an ester functional group in their main chain.
  • polyester refers to thermoset polyesters.
  • Certain preferred polyesters include polyesters formed from
  • dicarboxylic acid monomers including orthophthalic acid, isophthalic acid, and terephthalic acid, and hydrogenated versions thereof, and other aliphatic acids including succinic acid, glutaric acid and adipic acid. It will be appreciated that anhydrides of these dicarboxylic acid monomers may be present and indeed may be used as starting materials.
  • dicarboxylic acid monomers include isophthalic acid and hexahydrophthalic anhydride and 1 ,3 and 1 ,4-CHDAs.
  • the present inventors attribute poor durability at least in part to significant absorption of the binder in the UV region 290-400 nm.
  • the polyester does not absorb significantly at wavelengths over 300 nm, more preferably, at wavelengths over 290 nm.
  • dicarboxylic acids in which the two acid moieties are not in conjugation are preferred. These include hexahydrophthalic anhydride and other aliphatic diacids including cyclohexane 1 ,3 and 1 ,4 dicarboxylic acid, and isophthalic acid (owing to the meta configuration).
  • Any suitable polyol may be used, for example, a diol or triol.
  • Certain preferred diols include neopentyl glycol (NPG), 1 ,6-hexane diol (HD), ethylene glycol (EG), 1 ,2 propylene glycol, 1 ,3 propylene glycol, 1 ,4 butandiol, 2 methyl propane diol (MP diol), and butylethylpropylene diol (BEPD).
  • triols include trimethylolpropane (TMP), glycerol, and trimethylolethane (TME, also known as pentaglycerol).
  • TMP trimethylolpropane
  • TME trimethylolethane
  • the triol is trimethylolpropane (TMP).
  • the polyester is formed from isophthalic acid and trimethylolpropane (TMP). In some preferred embodiments, the polyester is formed from hexahydrophthalic anhydride and trimethylolpropane (TMP).
  • TMP trimethylolpropane
  • the polyester is formed of dicarboxylic acid monomer and polyol in a ratio of 7:3 to 3:7. Preferably, a slight excess of polyol is used, that is preferably the ratio of dicarboxylic acid monomer to polyol is 1 :>1 , for example about 4:6, for example about 4.5:5.5.
  • cross-linkers are used in the coatings and compositions of the present invention.
  • Suitable cross-linkers include melamine cross-linkers and isocyanate cross-linkers, which may be blocked or unblocked.
  • a one pot system refers to a composition that includes a cross-linker.
  • the one pot compositions are applied and cross-linked with heating up to a peak metal temperature of 250 °C. This heating will activate the cross-linker.
  • one pot systems may be used on a coil coating line to produce pre-coated metal strip.
  • a two pot system is provided as two compositions. One of the compositions is a hardener composition including a cross-linker. The two
  • compositions are mixed prior to application.
  • Two pot systems are sometimes referred to in the art as two-component or 2K systems and generally cross-link at ambient temperatures.
  • Preferred cross-linkers include melamine cross-linkers, for example, methylated melamine monomers. Where appropriate, blocked isocyanates may also be used.
  • the cross-linker is blocked.
  • the acid used to catalyse the melamine cross-linkers may be amine blocked, such that they unblock at temperatures above 140 °C.
  • Isocyanate cross-linkers may be blocked by chemicals such as methyl ethyl keto-oxime or caprolactam. Again, the blocking agent is released by thermal treatment.
  • Both melamine and isocyanate cross-linkers are used in coil coating applications.
  • a commercially available cross-linker suitable for use is Cymel ® 303 LF Resin (commercially available from a number of sources including Allnex).
  • isocyanate cross-linkers may be preferred.
  • the cross- linker may be an aliphatic polyisocyanate such as an isocyanate based on hexamethylene diiocyanate trimer (HDI polymer).
  • HDI polymer hexamethylene diiocyanate trimer
  • the cross-linker may be used in combination with a catalyst.
  • the composition may include a catalyst, while the hardener composition includes an isocyanate cross-linker.
  • Suitable catalysts are known the art and include organometallic catalysts such as organo tin compounds.
  • the catalyst may be selected to adjust the pot life and drying time of the mixed composition. Suitably, the pot life is around 20 minutes.
  • the mixed composition when applied at a thickness of 15-20 microns is surface dry in about 1 hour, and hard dry in about 4 hours.
  • cross-linkers are present at 2-8%wt, more preferably, 3-6%wt, most preferably 3-4%wt.
  • the numbers given are %wt of the composition and prior to application and drying to form the coating.
  • additives may be included. These may include catalysts, wetting agents, matting agents, flow agents and solvents.
  • Catalysts for polyester melamine systems are typically amine-blocked aromatic sulphonic acids. Suitably, they comprise 0.05% by wt of the total composition.
  • Pigment wetting aids may be used to help improve the dispersion of the pigment in the binder.
  • suitable wetting agents are known in the art and include DisperByk 180 (available from Altana). If present, a wetting agent may comprise 0.5%wt, but as the skilled person will appreciate, the amount included may depend on the amount of pigment and its surface area. Waxes may be used to modify the surface characteristics.
  • PTFE typically blends of PTFE and polyethylene (for example, Shamrock S-381 available from Shamrock) or even pure PTFE (for example, FluoroSLIP 225, also available from Shamrock). Matting agents such as silica are commonly used. Suitable matting agents include Syloid® ED5, available from Grace). If present, a matting agent may comprise 5%wt of the formulation depending upon the efficiency of the matting agent and the desired gloss level. Flow agents are added to aid the appearance of the final film by equalising surface tension. Suitably, high molecular weight acrylate or polyester materials are used and may comprise 0.5% by wt of the total composition.
  • compositions are formulated with about 60%wt solid content. That is, the non- solvent content of the compositions, also referred to as the resin component or solid component of the dried product, forms about 60%wt of the compositions.
  • Solvent as used herein may refer to a single solvent, or a combination of solvents. Suitable solvent blends for coil coatings are known in the art and typical consist of a mixture of aromatic solvents (for example SolvessoTM 150, available from ExxonMobil Chemical) and oxygenated solvents (for example, propylene glycol methyl ether acetate) in a 1 :1 ratio.
  • retention and maintenance of aesthetic appearance As used herein, this is determined by two methods, the percentage gloss retention level and chalking.
  • Outdoor durable systems are classified according to EN 10169-2 by the percentage gloss retention level attained after 2 years exposure in Florida or 2000 hours in a cabinet irradiated with UV light using fluorescent tubes as the source with a peak irradiance at 340 nm, operated on a 4 hours light and 4 hours humidity cycle.
  • a product with more than 30% gloss retention after 2000 hours in a cabinet irradiated with UV light using fluorescent tubes as the source is classified as an Ruv2 class material (EN10169-2).
  • a product with over 60% gloss retention after 2000 hours in a cabinet irradiated with UV light using fluorescent tubes as the source is classified as an Ruv3 class material.
  • the coatings described herein are Ruv2 class materials.
  • the coating formed using compositions as described herein are Ruv2 class materials.
  • Durability may also be determined by determining the extent of chalking (graded on a 0-10 scale as described herein).
  • Coated substrates were exposed to UV A conditions of cycling 4 h UV, 4 h condensation (EN13523-10 specification) or cycling 8 h UV or 4 h condensation (ASTM G154 Cycle 1 ).
  • the temperature during UV irradiation was controlled at 60 °C for both procedures but the temperature during condensation was 40 °C for the EN 13523-10 test and 50 °C for the ASTM G154.
  • the extent of chalking was determined according to ASTM D4214 Section 7.2.1 by running a finger along the surface then pressing the finger to a black sheet of paper, then visually quantifying the deposit.
  • the coatings described herein are rated 6 or more in the chalking test, more preferably 8 or more, more preferably 10.
  • suitably coatings produced by compositions described herein are rated 6 or more in the chalking test, more preferably 8 or more, more preferably 10.
  • This term as used herein refers to the property of materials as described herein to facilitate reaction of NO x gases to reduce the total amount of NO x gases in the atmosphere
  • ⁇ abatement performance was assessed by Cristal using a ranking system, in each case as described herein.
  • the paint films were irradiated with 0.89 W/m 2 UV at 340 nm for 1000, 1500 and 2000 hours using a filtered QUV A -340 light source (QUV Tester with Solar Eye 230V) before carrying out the test. This activates or increases the activity of the coatings over and above the un- exposed coatings.
  • the samples were irradiated with a UV fluorescent tube which emits 10 W/m 2 UV in the range of 300 to 400 nm.
  • the NO x that is used is NO at 225 ppb in nitrogen.
  • UVA is/NIR spectrophotometers
  • the UV absorbance was evaluated at each wavelength by scanning through the UV wavelengths from 190-450 nm at a speed of 1 19 nm/min. Readings were recorded by the instrument and plotted on an absorbance vs wavelength chart. The absorbance at 290 and 300nm was then recorded manually (Table 1 ). For convenience, the numbers 1 , 2, 3, 4, and 5 will be used generally to refer to those binders as described.
  • * %wt refers to the bine er and not the binder + solvent.
  • Binder dioxide (as 2000 h QUV A dioxide (as % of binder 2000 h
  • micronized photoactive titanium dioxide is advantageous in terms of durability and/or NO x performance (M in all cases denotes micronized), as can be seen by a comparison of the two examples using binder 4 in Table 2 (above).
  • the inventors attribute this to an increase in photo-activity owing to increased available surface area and the decrease in the unevenness of degraded surfaces leading to better gloss retention results.
  • Each of the binders 1 -5 was used to produce a coating having NO x activity. Binders 1 , 2, and 3 gave active coatings, while binders 4 and 5 gave active coatings having good durability (gloss retention) and excellent chalking results (Table 4). Each coating was produced as a one pot system.
  • Binder dioxide (as 2000 h QUV A
  • Coated panels according to the present invention have been exposed in Kuala Lumpur and Florida in private locations for 6 and 12 month periods. In each case, NO x reduction activity was measured on the unwashed panels and washed panels (washing removes dirt and particulate build up on the surface).
  • compositions of the present invention and compositions to form NO x active top coats of the present invention may be formed as follows:
  • Composition is applied to substrate at 35-55 microns wet film thickness using a suitable wire wound bar drawn through a pool of the coating placed at the far end of the panel to be coated.
  • the coated panel is then placed in an electric convection oven and baked to a PMT of 232 -241 °C with a dwell time 30-35 s.
  • the oven temperature is 265 °C.
  • the panel is then extracted from the oven and quenched in a water bath at room temperature.
  • the end result is a panel coated with a film of paint between 18 and 20 microns thick. Extent of reaction is determined using an MEK double rub test with adequate reaction being defined by more than 150 MEK double rubs (EN13523-1 1 ).
  • Two pot compositions may be produced in a similar manner, omitting the cross-linker.
  • a separate hardener composition is provided. The two compositions are combined before application. Binder as supplied in
  • a composition comprising a suitable cross-linker in solvent is provided as a hardener composition.
  • the composition may be applied using a bar coater, brush or spray gun. It will be appreciated that solvents may be selected to suit the application method. The selection of suitable solvents in apparent to one of skill in the art.
  • Composition should be applied to substrate at 35-55 microns wet film thickness using a suitable wire wound bar drawn through a pool of the coating placed at the far end of the panel to be coated.
  • the coated panel is then placed in an electric convection oven and baked to a PMT of 232-241 °C with a dwell time 30-35s.
  • the oven temperature is 265 °C.
  • the panel is then extracted from the oven and quenched in a bucket of water at room temperature.
  • the end result is a panel coated with a film of paint between 18 and 20 microns thick. Extent of reaction is determined using an MEK double rub test with adequate reaction being defined by more than 150 MEK double rubs (EN13523-1 1 ).
  • compositions are combined before application.
  • a composition comprising a suitable cross-linker in solvent is provided as a hardener composition.
  • the composition may be applied using a bar coater, brush or spray gun. It will be appreciated that solvents may be selected to suit the application method. The selection of suitable solvents in apparent to one of skill in the art.
  • any one or more of the aspects of the present invention may be combined with any one or more of the other aspects of the present invention.
  • any one or more of the features and optional features of any of the aspects may be applied to any one of the other aspects.
  • the discussion herein of optional and preferred features may apply to some or all of the aspects.
  • optional and preferred features relating to the composition, methods of making the composition and methods of using the composition, etc apply to aspects related to the coated substrate and material.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Inorganic Chemistry (AREA)
  • Laminated Bodies (AREA)
  • Paints Or Removers (AREA)

Abstract

L'invention concerne un substrat métallique revêtu comprenant un matériau actif de NOx. Le matériau actif de NOx comprend du dioxyde de titane photosensible et un liant. Le liant comprend de la silicone et un polymère, et la teneur en silicone du liant est d'au moins 30 % en poids des solides dans le liant. L'invention concerne également des systèmes à un ou deux composants pour fournir de tels revêtements.
PCT/EP2015/080893 2014-12-23 2015-12-21 Revêtements réduisant la pollution WO2016102520A1 (fr)

Applications Claiming Priority (2)

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GB201423090 2014-12-23

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080003367A1 (en) * 2004-09-14 2008-01-03 John Stratton Composition Useful for Providing Nox Removing Coating On Material Surface
US20080011195A1 (en) * 2004-06-04 2008-01-17 Peter Grochal Coating Composition
US20110059315A1 (en) * 2009-09-10 2011-03-10 The National Titanium Dioxide Co. Ltd. (Cristal) Methods of producing titanium dioxide nanoparticles
US20130164542A1 (en) * 2007-05-10 2013-06-27 Ppg B.V. Primer Composition

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080011195A1 (en) * 2004-06-04 2008-01-17 Peter Grochal Coating Composition
US20080003367A1 (en) * 2004-09-14 2008-01-03 John Stratton Composition Useful for Providing Nox Removing Coating On Material Surface
US20130164542A1 (en) * 2007-05-10 2013-06-27 Ppg B.V. Primer Composition
US20110059315A1 (en) * 2009-09-10 2011-03-10 The National Titanium Dioxide Co. Ltd. (Cristal) Methods of producing titanium dioxide nanoparticles

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