NIR-inert substrates comprising bis-oxodihydroindolylen-benzodifuranones

Abstract

A method for producing infra-red inert substrates, including molded polymeric articles, films, fibers and coatings and other organic and inorganic materials, by incorporating into the substrate or onto the surface of the substrate an effective amount of a dispersed bis-oxodihydroindolylen-benzodifuranone colorant. The thus obtained, also claimed substrates so produced are reflective and transparent to much of the near infra red radiation not reflected. There are multiple applications for cases of devices comprising electronic components, outdoor construction elements, outdoor furniture, automotive, marine or aerospace parts, laminates, artificial leather or textile materials, as well as in polychrome printing processes and optical fibers. The thus obtained substrates can also be subjected to laser welding. New bis-oxo-dihydroindolylen-benzodifuranone compounds are also claimed.

Claims

1. A method for preparing a near infra red inert organic or inorganic substrate, the method comprising: applying a composition onto a surface of a substrate selected from the group consisting of a reflective organic or inorganic substrate, a transparent organic or inorganic substrate, and a semi-transparent organic or inorganic substrate, the composition comprising: a polymeric binder; and a bis-oxodihydroindolylen-benzodifuranone pigment of formula ##STR00007## or an isomer or tautomer thereof, wherein: the bis-oxodihydroindolylen-benzodifuranone pigment of formula (Ia) or (Ib) or isomer or tautomer thereof is in the form of particles (i) of mean size ≦0.5 μm or (ii) of mean size >0.5 μm and thickness ≧0.4 μm, which particles are well dispersed in the composition and are present in an amount effective to impart: an infra red reflectance of 20% to the resulting near infra red inert substrate when the substrate is the reflective organic or inorganic substrate, an infra red transmittance of ≧30% to the resulting near infra red inert substrate when the substrate is the transparent organic or inorganic substrate, or a combined infra red reflectance and transmittance of 25% to the resulting near infra red inert substrate when the substrate is the semi-transparent organic or inorganic substrate, each at wavelengths from 850 to 1600 nm; R.sub.1 and R.sub.6 are each independently of the other H or F; R.sub.2, R.sub.4, R.sub.5, R.sub.7, R.sub.9, and R.sub.10 are H, F, or Cl; R.sub.3 and R.sub.8 are H, NO.sub.2, OCH.sub.3, OC.sub.2H.sub.5, Br, Cl, CH.sub.3, C.sub.2H.sub.5, N(CH.sub.3).sub.2, N(CH.sub.3)(C.sub.2H.sub.5), N(C.sub.2H.sub.5).sub.2, α-naphthyl, β-naphthyl or SO.sub.3.sup.−; R.sub.1 is identical to R.sub.6, R.sub.2 is identical to R.sub.7, R.sub.3 is identical to R.sub.8, R.sub.4 is identical to R.sub.9, and/or R.sub.5 is identical to R.sub.10; and the amount effective of the particles is of from 0.01 to 50% by weight, based on the total weight of the composition.

2. The method according to claim 1, wherein the substrate is comprises a polymer selected from the group consisting of a thermoplastic polymer, an elastomeric polymer, and a crosslinked or inherently crosslinked polymer.

3. The method according to claim 1, wherein R.sub.1 and R.sub.6 are H.

4. The method according to claim 1, wherein the composition is in the form of a coating system or preformed film which both adheres to the substrate and is selected from the group consisting of an automotive coating, a marine coating, a paint, an ink, a laminate, a receiving layer for printing applications, and a protective or decorative coating for glazing applications.

5. The method according to claim 1, wherein: the composition as applied to the substrate is in the form of a mark showing a pattern which is different when viewed or recorded under sequential irradiation by two electromagnetic waves of different emission spectra in the range from 400 nm to 2 μm under the same or different dihedral angles to the surface of the substrate, or viewed or recorded under irradiation by electromagnetic waves of the same emission spectrum in the range from 400 nm to 2 μm under different dihedral angles to the surface of the substrate, which mark comprises at least two different pigments, each pigment being embedded in a wet, dry or cured ink which may be the same or different for part or all of the pigments, at least two wet, dry or cured inks reflecting differently under irradiation by electromagnetic waves of emission spectrum in the range from 400 nm to 2 μm, and the amount effective of the particles of formula (Ia) or (Ib) or an isomer or tautomer thereof is present in at least one of the wet, dry or cured inks.

6. The method according to claim 1, wherein: the composition as applied to the substrate is in the form of a mark identifying the substrate and comprising the pigment of formula (Ia) or (Ib) or an isomer or tautomer thereof; and applying the composition comprises recording the mark under irradiation by electromagnetic waves of wavelength from 715 to 2000 nm.

7. The method according to claim 1, wherein: the substrate is a case of a device comprising electronic components; and the composition further comprises a white, low- or non-NTR-absorbing black, colour, metallic or interference pigment, in a weight ratio of from 1:99 to 99:1 relative to the pigment of formula (Ia) or (Ib) or isomer or tautomer thereof.

8. The method according to claim 1, wherein: the substrate is an outdoor construction element, outdoor furniture, automotive, marine or aerospace part, laminate, artificial leather or textile material; and the composition further comprises a white, low- or non-NTR-absorbing black, colour, metallic or interference pigment, in a weight ratio of from 1:99 to 99:1 relative to the pigment of formula (Ia) or (Ib) or isomer or tautomer thereof.

9. The method according to claim 1, wherein the composition is in the form of a black ink for a polychrome printing process.

10. The method according to claim 1, wherein the composition as applied to the substrate is in the form of a film.

11. The method according to claim 2, wherein the polymer is selected from the group consisting of a polyolefin, a polyamide, a polyurethane, a polyacrylate, a polyacrylamide, a polyvinyl alcohol, a polycarbonate, a polystyrene, a polyester, a polyacetal, a natural or synthetic rubber, and a halogenated vinyl polymer.

12. The method according to claim 1, wherein the bis-oxodihydroindolylen-benzodifuranone pigment of formula (Ia) or (Ib) or isomer or tautomer thereof is in the form of particles of mean size ≦0.5 μm.

13. The method according to claim 1, wherein the bis-oxodihydroindolylen-benzodifuranone pigment of formula (Ia) or (Ib) or isomer or tautomer thereof is in the form of particles of mean size >0.5 μm and thickness ≧0.4 μm.

14. The method according to claim 1, wherein the substrate is the reflective organic or inorganic substrate, and the resulting near infra red inert substrate has an infra red reflectance of ≧20%.

15. The method according to claim 1, wherein the substrate is the transparent organic or inorganic substrate, and the resulting near infra red inert substrate has an infra red transmittance of ≧30%.

16. The method according to claim 1, wherein the substrate is the semi-transparent organic or inorganic substrate, and the resulting near infra red inert substrate has a combined infra red reflectance and transmittance of ≧25%.

17. The method according to claim 1, wherein: the composition further comprises a white pigment in a weight ratio of from 1:99 to 99:1 relative to the pigment of formula (Ia) or (Ib) or isomer or tautomer thereof; and the method further comprises applying a basecoat to the composition as applied to the substrate, the basecoat comprising at least one of a black pigment, a color pigment, a metallic pigment, and an interference pigment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a daylight picture of a sample according to example 18.

(2) FIG. 1B shows a picture of a sample according to example 18 under infra red light exposure using a filter (passthrough 715-1000 nm).

(3) FIG. 2 is an electronic absorption spectrum of the printed polyester substrate according to example 18, measured against blank Melinex® (reference 306, thickness 100 μm) with a Lambda™ 15 UV-VIS spectrophotometer (Perkin-Elmer).

(4) FIG. 3A is a daylight picture of a sample according to example 19.

(5) FIG. 3B is a picture of a sample according to example 19 under infra red light exposure using a filter (passthrough 715-1000 nm).

(6) FIG. 4A is a picture of the samples setup according to example 21, wherein the print on polyester according to example 18 is laid on top of the right side of two adjacent labels, the top one printed with an IR absorber and the bottom one printed with C. I. Pigment Black 7.

(7) FIG. 4B is a picture of the same samples setup according to example 21 under infra red light exposure using a filter (passthrough 715-1000 nm).

(8) FIG. 5A is a daylight picture of the samples setup according to example 22), wherein an ink comprising the compound according to example 12b of WO 00/24 736 is printed on a paper sheet, the left half of which has previously been printed with an ink comprising an IR absorber.

(9) FIG. 5B is a picture of the same sample according to example 22 under infra red light exposure using a filter (passthrough 715-1000 nm).

(10) FIG. 1A, FIG. 1B, FIG. 3A, FIG. 3B, FIG. 4A, FIG. 5A and FIG. 5B are all colour photographic pictures which are digitalized then converted to greyscale.

(11) The examples that follow illustrate the invention, without limiting the scope thereof (unless otherwise specified, “%” is always % by weight):

Example 1

(12) A 12% millbase is prepared by dispersing 5.4 parts of the compound according to example 12b of WO 00/24 736 in 9.0 parts of butyl acetate for 15 minutes in a Skandex® disperser. 25.4 parts of Maprenal® MF 650 (30% in isobutanol/n-butanol/xylene 20:1:1, Solutia Inc.) are added and the mixture is dispersed again. Then, the pigment concentration is let down to 6% by adding 25.4 g cellulose acetobutyrate and 33.8 g of Dynapol® H700 and finally mixing. A layer is bar-coated on a glass plate with a 100 μm spiral bar. The transmission at 1200 nm is 68%. The CIE-colouristics are: L*=26.8, C*=1.3, h=290.2. The transmission value is enhanced to 77% by additionally using a dispersant.

Example 2

(13) It is proceeded similarly as in example 1, with the difference that the pigment concentration is decreased to 1%. The transmission at 1200 nm is 92%.

Example 3

(14) The compound according to example 12b of WO00/24736 is treated by wet-milling for 1 hour at 40° C. in the 10-fold amount of isopropanol (Skandex®), then filtered and dried. An easily dispersible pigment powder is obtained.

Example 4

(15) An about 0.3 mm thick PVC sheet comprising 0.2% of the pigment powder according to example 3 is prepared in conventional manner on a two-roll mill at 150-160° C. The transmission in the wavelength range from 850 to 1600 nm varies from 65% to 83%.

Example 5

(16) An about 0.4 mm thick flexible PVC film comprising 0.2% by weight of the pigment powder according to example 3 is prepared in conventional manner on a two-roll mill at 150-160° C. The temperature increase is determined in a heat box according to ASTM D4803-97 (2002)e1 under a commercial 250 W IR lamp. The PVC film shows about 7° C. less heat build up, as compared with a similar film containing 0.2% of commercial C Black FW 200 (Evonik, C. I. Pigment Black 7).

Example 6

(17) Polypropylene samples comprising 0.2% of the pigment powder according to example 3 are prepared by extrusion and injection moulding at 220° C. The results are comparable to those of example 4. Especially remarkable is the disapparition of the absorption peak at around 1.2 μm, at which wavelength the transmittance (˜77%) is even better than that of colourless polypropylene (˜74%). The CIE-colouristics are: L*=29.1, C*=3.5, h=79.4.

Example 7

(18) A mixture of the pigment powder according to example 3 and a LDPE-wax (1:1) is introduced at 0.1% in polypropylene (HF 420 FB, Borealis) at 260° C./56.2bar (800 psi) pressure and spun to 80 dtex/10 filaments with a stretching ratio of 1:4. A fine black yarn is obtained, which is woven to a polypropylene fabric showing about 10° C. less heat uptake and a lower NIR signature, compared with a similar fabric comprising with C. I. Pigment Black 7.

Example 8

(19) An about 25 μm LDPE (Lupolen® 1840D, Basell) blow film thick comprising 1% of the pigment powder according to example 3 is prepared in conventional manner by extrusion and blow moulding at 200° C. The transmission in the wavelength range from 800 nm to 1500 nm varies from 87 to 90%. A comparative sample comprising commercial C Black FW 200 (Evonik) shows values of 38 to 56%.

Example 9

(20) Polyethyleneterephthalate (PET Arnite® D04-300, DSM) samples comprising 0.02% of the pigment powder according to example 3 are prepared by extrusion and injection moulding at 280° C. The results are similar to those of example 4.

Example 10

(21) Polymethylmethacrylate (PMMA 6N Glasklar™, Röhm GmbH, Darmstadt) samples comprising 0.05% of the pigment powder according to example 3 are prepared by extrusion and injection moulding at 200° C. The results are similar to those of example 4.

Example 11

(22) It is proceeded similarly to example 6, with the difference that 1% of titanium white is further added to the composition. An attractive neutral grey is obtained, the saturation and the hue of which are almost identical to those of carbon black, however with a much higher reflectivity:

(23) TABLE-US-00001 L* C* h example 5 67.8 3.6 246.4 Pigment Black 7 26.5 3.0 259.9

Example 12

(24) Coatings comprising the pigment powder according to example 3 are sprayed onto a steel plate onto which a primer comprising titanium white and aluminum flakes has been previously applied, giving a black appearance. The reflectance is significantly higher than that of the primer itself in the region from 800 nm to 1.35 m, and nearly identical from 1.35 μm to 1.6 μm.

Example 13

(25) A mill base is prepared by dispersing in a Skandex® 15.0 parts of the compound according to example 12b of WO 00/24 736, 13.5 parts Ciba® EFKA®4585, 1.2 parts dimethylethanolamine (DMEA 10%), 0.3 parts Ciba® EFKA® 2550 and 70.0 parts deionized water. 2 parts of this mill base are then dispersed into 18 parts of a waterborne polyurethane-acrylate hybrid clear system (0.54 parts Maprenal® MF900 W/95, 0.8 parts Surfynol® 104E, 0.3 parts Surfynol® MD20, 0.4 parts Envirogen® AE02, 5.51 parts butylglycol, 2 parts n-butanol, 0.2 parts Dow® DC57, 3.5 parts Viscalex® HV30, 0.25 parts DMEA, 37.25 parts APU® 1012 and 49.25 parts deionized water). Coatings comprising 4% pigment on solids are sprayed onto aluminum plates and a steel plate onto which a white primer has been previously applied giving a black appearance.

Example 14

(26) A mill base is prepared by dispersing in a Skandex® 2% of the pigment powder according to example 3 in a PES-CAB two coat system. Coatings are sprayed onto aluminum plates giving a black appearance.

Example 15

(27) A varnish is prepared by dispersing in a Skandex® 6% of the compound according to example 12b of WO 00/24 736, nitrocellulose and alcohol. This ink is applied with a hand coater (20μ wet film thickness) onto a white substrate, on which an image has been applied using an ink comprising a slighly coloured NIR absorber. Visually, the whole sample appears grey and the image can very uneasily be distinguished. However, when the samples are photographed using an IR filter (715-1000 nm), an image is obtained which is very similar to the image before application of the compound according to example 12b of WO 00/24 736. When a perylene black is used instead of the compound according to example 12b of WO 00/24 736, violet prints are obtained instead of desirably grey prints.

Example 16

(28) A varnish is prepared by dispersing in a Skandex® 3% of the pigment powder according to example 3 in a vinyl binder system (Movital® B20H, ethoxypropanol, methoxypropylacetate, diacetonealcohol). This ink is applied with a by hand-coater no 2 (12 μm wet film thickness) onto an aluminium foil to provide a greyish black print. When a perylene black is applied instead of the pigment powder according to example 3, violet prints are obtained instead of desirably grey prints.

Example 17 (Clear Varnish Preparation)

(29) 1 Kg of clear varnish is prepared by mild stirring at 23° C. of a formulation containing 30 g Citrofoll® BII (ATBC, Jungbunz-lauer), 150 g nitrocellulose chips AH27 containing 20% of ATBC (Christ), 10 g ethylcellulose N7 (Herkules), 40 g Kunstharz SK (Degussa), 100 g 1-ethoxypropanol, 200 g ethylacetate and 470 g ethanol. The thus obtained clear varnish has a viscosity of 18 seconds (Ford Cup n° 4).

Example 18

(30) A nitrocellulose ink is prepared in a Skandex® by dispersing for 2 hours in a 400 ml glass bottle 15 parts of the pigment powder according to example 3 and 230 g of glass beads of 2 mm diameter into 85 parts of the clear varnish according to example 17. Application by hand-coater n° 2 (12 μm wet film thickness) on transparent polyester foil (Melinex®, reference 306, thickness 100 μm) results in a black print. Photography in daylight without filter shows an intensely coloured black image (see FIG. 1A and FIG. 2), whereas photography under infra red light using a filter (passthrough 715-1000 nm) shows a transparent colourless image of the print (see FIG. 1B).

Example 19 (Comparative)

(31) A nitrocellulose ink is prepared by stirring with a Dispermat® at 6000 rpm for 20 minutes in a 400 ml glass bottle 25 parts Microlith® Black C-A (containing 60% C. I. Pigment Black 7), 2 parts nitrocellulose Chips AH27 (containing 20% of ATBC, Christ), 3 parts Joncryl® 68 (BASF), 5 parts Dowanol® PM (Fluka), 18 parts ethylacetate and 47 parts ethanol. Application by hand-coater n° 2 (12 μm wet film thickness) on transparent polyester foil (Melinex®, reference 306, thickness 100 μm) results in a black print. Both photographs in daylight and under infra red light using a filter (passthrough 715-1000 nm) show an intensely coloured black image (see FIG. 3A and FIG. 3B).

Example 20 (Comparative Coloristic Measurements of Examples 18 and 19)

(32) The samples according to examples 18 and 19 are coloristically measured with CGREC for Windows Version 2.61.05. Comparative example 19 is measured against example 18 taken as reference. The shade of the print obtained according to comparative example 19 is much yellower than that according to example 18 (ΔH*=2.6) and the colour strength of the print obtained according to comparative example 19 is 34% lower than that according to example 18:

(33) TABLE-US-00002 colour strength L* C* h [%] ΔH* contrast paper light area 96.3 4.0 91.8 dark area 33.1 2.2 31.5 example 18 over light 33.2 2.2 32.4 100 — over dark 26.5 1.4 8.6 example 19 over light 33.4 2.2 36.4  66 2.6 over dark 32.6 3.3 81.3

Example 21

(34) The print on polyester according to example 18 is laid on top of part of two adjacent labels, the first printed with an IR absorber and the second printed with C. I. Pigment Black 7. This set up is photographed both in daylight (see FIG. 4A) and under infra red light using a filter (passthrough 715-1000 nm) (see FIG. 4B). The label printed with an IR absorber (top left) appears almost colourless under daylight and grey under IR light, but where it is covered by the print on polyester according to example 18 (top right), it is entirely masked under daylight (FIG. 4A) and appears only under IR light (FIG. 4B). The label printed with carbon black (bottom left) appears black under daylight and dark grey under IR light (likely due to some partial IR reflection), but where it is covered by the print on polyester according to example 18 (bottom right), it is entirely masked under daylight (FIG. 4A) and appears only under IR light (FIG. 4B). That is, a pattern printed for example with carbon black or another colourless or coloured IR absorber, covered with a print layer according to example 18 is hidden under daylight but clearly recognizable under infra red light using a filter (passthrough 715-1000 nm), enabling excellent marking or security applications.

Example 22

(35) A security element is prepared by overprinting an ink containing the pigment powder according to example 3 on top of a print containing an IR absorber. An IR absorber containing offset ink is first printed on the left half of paper sheets with a Prufbau® apparatus (1.3 g/m.sup.2). An ink according to example 18 is then applied on the bottom part of the previous print by hand-coater n° 2 (12 m wet film thickness). Photography in daylight shows almost no difference between the left part with the ink according to example 18 printed on an underlayer with the IR absorber (see FIG. 5A), whereas photography under infra red light using a filter (passthrough 715-1000 nm) reveals a large difference (see FIG. 5B).

Example 23

(36) It is proceeded as in example 7, with the difference that the pigment powder according to example 3 is introduced at 1.0% in polypropylene and the fabric is used to manufacture camouflage nets.

Example 24

(37) It is proceeded similarly to example 1. A millbase is prepared by dispersing 1.8 parts of the compound according to example 12b of WO00/24 736 in 3.6 parts of butyl acetate for 15 minutes in a Skandex® disperser. 26.5 parts of Maprenal® MF 650 are added and the mixture is dispersed again. Then, the pigment concentration is let down to 2% by adding 26.5 parts of cellulose acetobutyrate and 35.0 parts of Dynapol® H700 and finally mixing. A layer is bar-coated on glass with a 100 μm spiral bar. The transmission in the wavelengths from 800 to 1500 nm varies from 77% to 87%.

Example 25 (Comparative)

(38) It is proceeded similarly to example 24, with the difference that C Black FW 200 (Evonik, C. I. Pigment Black 7) is used instead of the compound according to example 12b of WO 00/24 736. The transmission in the wavelengths from 800 to 1500 nm shows values around 22%.

Example 26

(39) It is proceeded as in example 1, with the difference that the pigment concentration is decreased to 1%. The paint is sprayed onto aluminium plates giving a clean black appearance. A typical thermosetting acrylic top coat is then applied, which contains a combination of UV absorber and hindered amines (HALS), like for example Tinuvin® 900 and Tinuvin® 292 (both Ciba).

Example 27

(40) A 50:50 pigment: aluminium reduction is prepared by mixing the millbase according to example 26 and an 8% aluminium base paint containing a 60% aluminium paste (Silverline® SS3334AR). The paint is sprayed onto aluminium plates giving a shiny black appearance. A typical thermosetting acrylic top coat is then applied, which contains a combination of UV absorber and hindered amines (HALS), like for example Tinuvin® 900 and Tinuvin® 292 (both Ciba).

Example 28

(41) A 20:80 pigment: TiO.sub.2 white reduction is prepared by mixing the millbase according to example 26 and a white base paint containing 20% of titanium dioxide (Kronos® 2310). The paint is sprayed onto aluminium plates giving a grey appearance. A typical thermosetting acrylic top coat is then applied, which contains a combination of UV absorber and hindered amines (HALS), like for example Tinuvin® 900 and Tinuvin® 292 (both Ciba).

Example 29

(42) A millbase is prepared by dispersing 0.6 parts of the compound according to example 12b of WO00/24736 and titanium dioxide (Kronos® 2310) in 3.8 parts of xylene, then in 29.2 parts of an alkydmelamine lacquer based on F 310™ (60% in Solventnaphtha® 100, Bayer) and 5.0 parts of the aminoplast crosslinker Cymel® 327 (Cytec) in a Skandex® disperser. A layer is bar-coated with a 100 μm spiral bar on an aluminium plate and baken in the oven for 30 minutes at 130° C. A grey colour is obtained.

Example 30

(43) The pigment powder according to example 3 is spun at 0.1% concentration into PES fibres (Polyester granulate GL 6105 type, Kuag Elana GmbH) at 110 dtex/24 filaments. A fine black yarn is obtained, which is weaved to a polyester fabric showing less heat uptake and a lower NIR signature as a comparable fabric comprising 0.1% C. I. Pigment Black 7.

Example 31

(44) It is proceeded as in example 30, with the difference that the concentration of the pigment powder according to example 3 is increased to 1%.

Example 32 (‘Let-Down’ Clear)

(45) A ‘let-down’ clear is prepared by stirring 29 parts Binder A (Bayhydrol® VPLS 2378, Bayer) and 40 parts Binder B (Bayhydrol® VPLS 2341, Bayer), then adding individually 2.5 parts butyl glycol and 6 parts n-methyl-pyrrolidone under stirring. The mixture is stirred for 15 minutes prior to further component additions. 15 parts Crosslinker A (Bayhydur® BL 5140, Bayer) and 7.5 parts Crosslinker B (Trixene® BI 7986) are added separately under stirring. The subsequent mixture is stirred for 1 hour prior to further additions to ensure all components are homogeneously mixed.

Example 33 (Titanium Dioxide Pigment Paste)

(46) A continuous phase is prepared by mixing 38.5 parts de-ionised water, 4.2 parts of Efka® 4580 (pigment dispersant, Ciba), 0.3 parts of Efka® 2550 (antifoam agent, Ciba) and 0.4 parts of Optigel® SH (anti-settlement agent), using a disperser equipped with a Cowles blade (toothed blade). Once homogeneous, 55.0 parts titanium dioxide pigment (Kronos® 2310) are added under stirring. Once all the pigment is incorporated, the pH of the slurry is adjusted in the range 7.5 to 8.5 by use of a 10% aqueous solution of dimethylethanolamine. The slurry is then predispersed using the same disperser/Cowles blade combination for 30 minutes to ensure large pigment agglomerates are adequately ‘wetted-out’ in the continuous phase. The ‘wetted-out’ slurry is transferred to a re-circulation dispersion mill filled with zirconia grind media until maximum particle size of the dispersed pigment is ≦10 μm according to a Hegmann grind gauge.

Example 34 (Comparative Carbon Black Pigment Paste)

(47) A continuous phase is prepared by mixing 65.7 parts deionised water, 10.0 parts of Efka® 4580 (pigment dispersant, Ciba) and 0.3 part of Efka® 2550 (antifoam agent, Ciba) with a disperser equipped with a Cowles blade (toothed blade). Once homogeneous, 12.0 parts Colour Black™ FW 200 (carbon black pigment, Evonik) are added under stirring. Once all the pigment is incorporated, the pH of the slurry is adjusted in the range 7.5 to 8.5 by use of a 10% aqueous solution of dimethylethanolamine. The slurry is then further processed as in example 33.

Example 35 (NIR-Inert Black Pigment Paste)

(48) A continuous phase is prepared by mixing 61.2 parts deionised water, 12.5 parts of Efka® 4580 (pigment dispersant, Ciba) and 0.3 parts of Efka® 2550 (antifoam agent, Ciba) by stirring using a disperser equipped with a Cowles blade (toothed blade). Once homogeneous, 20.0 parts of the pigment powder according to example 3 are added under stirring to the continuous phase. Once all the pigment is incorporated, the pH of the slurry is adjusted in the range 7.5 to 8.5 by use of a 10% aqueous solution of dimethylethanolamine. The slurry is then further processed as in example 33.

Example 36 (Deep Grey NIR Reflective Primer; 70:30 White:Black)

(49) To 39 parts of ‘let-down’ clear according to example 32, 28 parts titanium dioxide pigment paste according to example 33 and 32 parts IR-reflective black paste according to example 35 are added separately under stirring. Once all pastes are completely homogenised, 1 part of Efka® 3570 (levelling additive, Ciba) is added under stirring. The pH of the primer is adjusted by the addition of a 10% aqueous solution of dimethylethanolamine until a stable pH in the range 7.5 to 8.5 is obtained. To prepare the primer for final application, deionised water is added to the mixture until a viscosity of 30-35 seconds in a DIN 4 viscosity flow cup (23° C.) is obtained. This primer formulation is applied onto 1.0 mm thick glass panels using a drawdown bar to a dry film thickness of 40-50 μm, sufficient for full optical (visible light) opacity. After a flash off period of 30 minutes at ˜23° C., the panels are pre-baked for 15 minutes at 80° C. to drive off excess water and solvent, followed by a stowing cycle of 30 minutes at 150° C. to achieve full cure.

Example 37 (Middle Grey NIR Reflective Primer; 85:15 White:Black)

(50) To 44 parts of ‘let-down’ clear according to example 32, 37 parts titanium dioxide pigment paste according to example 33 and 18 parts IR-reflective black paste according to example 35 are added separately under stirring. Once all pastes are completely homogenised, 1 part of Efka® 3570 (levelling additive, Ciba) is added under stirring. The pH of the primer is adjusted by the addition of a 10% aqueous solution of dimethylethanolamine until a stable pH in the range 7.5 to 8.5 is obtained. To prepare the primer for final application, deionised water is added to the mixture until a viscosity of 30-35 seconds in a DIN 4 viscosity flow cup (23° C.) is obtained, which is then applied onto glass panels according to the procedure of example 36.

Example 38 (Black NIR-Inert Primer)

(51) It is proceeded in analogy to example 36, with the difference that only the NIR-inert black paste according to example 35 and no titanium dioxide are used as pigments.

Example 39 (Comparative Middle Grey Primer; 95:5 White:Black)

(52) To 46 parts of ‘let-down’ clear according to example 32, 43 parts titanium dioxide pigment paste according to example 33 and 11 parts carbon black pigment paste according to example 34 are added separately under stirring. Once all pastes are completely homogenised, 1 part of Efka® 3570 (levelling additive, Ciba) is added under stirring. The pH of the primer is adjusted by the addition of a 10% aqueous solution of dimethylethanolamine until a stable pH in the range 7.5 to 8.5 is obtained. To prepare the primer for final application, deionised water is added to the mixture until a viscosity of 30-35 seconds in a DIN 4 viscosity flow cup (23° C.) is obtained. This primer formulation is then applied onto 1.0 mm thick glass panels according to the procedure of example 36.

Example 40 (Comparative Black Primer)

(53) It is proceeded according to example 36, with the difference that the carbon black pigment paste according to example 34 is used as the only pigment.

(54) The approximative transmission and the reflection of the cured glass panels according to examples 36, 37, 38, 39 and 40 are then measured with a Lambda™ 900 UV/VIS spectrophotometer (Perkin Elmer) in the near infra-red spectral range from 700 to 1200 nm. As compared with the conventional, carbon black comprising grey primer according to comparative example 39, the grey primers according to examples 36 and 37 show about 3 to 6 times higher NIR reflectance as well as a significant NIR transmission above about 850 nm (no transmission is observed with comparative example 39 comprising carbon black). The black sample according to example 38 is also superior to the black sample according to comparative example 40 both in transmission and in reflection throughout the measured range. Above about 1000 nm, the sample according to example 38 transmits most NIR radiation and reflects a large part of the remaining, not transmitted NIR radiation, while the sample according to comparative example 40 transmits no NIR radiation and reflects about 4 times less NIR radiation than the sample according to example 38.

(55) Similar results are obtained when the waterborne stoving formulation according to examples 32 to 40 is replaced by stoving solventborne primers and primers formulated for different curing conditions, for example ambient cured, solventborne and waterborne acrylic (and/or polyester)+isocyanate and epoxide+polyamine, 2-component primer systems.

Example 41

(56) According to procedures well-known to skilled artisans, the grey primer formulation according to example 37 is applied to a scale model car body by spraying. A pigmented layer comprising the pigment according to example 2 of EP application 08 157 426.1 (C. I. Pigment Yellow 139) and a clear coat, each based on coating formulations similar to and compatible with those of example 32 to 40, are then applied wet-on-wet. Curing then leads to a very uniform colouration independently of the angle of view. The model car body is then mounted on a chassis equipped with a remote control. Remote controls of relatively low heat specifications can be used without failure under sun exposure, decreasing the overall costs.

Example 42

(57) According to procedures well-known to skilled artisans, the primer formulation according to example 36 is applied to an automotive hood by spraying (dry film thickness ˜50 μm). After curing, the primer layer is overcoated by spraying first a layer of the red composition according to example 1 of EP 1 549 706 B1 (dry film thickness ˜20 μm), then in a wet-on-wet process with an usual protective transparent topcoat layer comprising UV absorbers and antioxidants (dry film thickness ˜50 μm). The red car hood uptakes only little heat under sun exposure and leads to enhanced durability of the coating and longer time to failure of the onboard electronic equipment (engine and brakes control systems).