ENVIRONMENTALLY STABLE ORGANIC PIGMENTS

Abstract

The invention relates to environmentally stable organic pigment which is modified by a polymer and characterized by a change of Delta E (dE) of less than 5 after 2000 h simulated accelerated weathering measured according to DIN EN ISO 11341 in silicone paint.

Claims

1. Environmentally stable organic pigment which is modified by a polymer and characterized by a change of Delta E (dE) of less than 5 after 2000 h simulated accelerated weathering measured according to DIN EN ISO 11341 in silicone paint.

2. Environmentally stable organic pigment according to claim 1, wherein the organic pigment is chosen from the group of azo, isoindolinone, isoindoline, anthanthrone, thioindigo, thiazineindigo, triarylcarbonium, quinophthalone, anthraquinone, dioxazine, phthalocyanine, quinacridone, quinacridonequinone, indanthrone, perylene, perinone, pyranthrone, diketopyrrolopyrrole, isoviolanthrone, and azomethine pigments.

3. Environmentally stable organic pigment according to claim 1, wherein the polymer is a the bulk polymer, solution polymer or a water-dispersible polymer.

4. Aqueous organic pigment dispersion comprising a pigment according to claim 1 which is dispersed in water in the presence of a wetting or dispersing agent and a carrier.

5. Aqueous organic pigment dispersion according to claim 4 which comprises a surfactant.

6. Aqueous organic pigment dispersion according to claim 4, wherein the wetting or dispersing agent may be used as single component or as a mixture of different wetting and/or dispersing agents.

7. Aqueous organic pigment dispersion according to claim 4, wherein the dispersing agent represents at least 0.1 and up to 25% by weight of the organic pigment particle weight.

8. Aqueous organic pigment dispersion according to claim 4, wherein pigment is modified with an acrylic, polyester, polyurethane, polyester-polyurethane, epoxy resin, vinyl chloride resin, vinyl ester resin, ethylene vinyl ester, styrene, styrene acrylic resin, styrene acrylonitrile resin, polyimide, polycarbonate, amino resin, phenolic resin, polysulfide, urea resins, polyethylene (meth) acrylic acid copolymers, carboxylated polybutadiene or a perfluorinated sulfonic acid polymer or a combination of these polymers.

9. Aqueous organic pigment dispersion according to claim 4, wherein the solid pigment content is in the range from 10 and 80% by weight.

10. Aqueous organic pigment dispersion according to claim 4, wherein the polymer content is in the range from 10 and 80% by weight.

11. Method to prepare an environmentally stable organic pigments dispersion according to claim 4, which comprising the steps of: (a) dispersing an organic pigment using a wetting or dispersing agent in water; (b) adding at least one aqueous polymer dispersion to the dispersed organic pigment of step (a) to form a first dispersed pigment/polymer resin/aqueous mixture; and (c) heating the first dispersed pigment/polymer resin/aqueous mixture under stirring to form an environmentally stable organic pigment dispersion; and (d) optionally removing the water from the environmentally stable organic pigment dispersion to obtain dried environmentally stable organic pigments.

12. Method according to claim 11, wherein the wetting and dispersing agent is selected from the group consisting of anionic, cationic or non-ionic bulk polymer, solution polymer or a water-dispersible polymer.

13. Method according to claim 11, wherein the polymeric dispersant has a number average molecular weight of 1,000 to 20,000 Daltons.

14. Method according to claim 11, wherein the D50 value is 10 μm or less.

15. Method according to claim 11, wherein the progress of the dispersion is monitored until the target value for the D50 value is reached.

16. Method according to claim 11, wherein the dispersed pigment/polymer resin/aqueous mixture is heated up to a temperature up to 80° C. in step (c).

17. Use of the environmental stable pigment of claim 1 for pigmenting exterior or interior decorative coatings, automotive coatings or industrial coatings.

18. Use of the pigment dispersion of claim 4 for pigmenting exterior or interior decorative coatings, automotive coatings or industrial coatings.

Description

EXAMPLE 1: FORMATION OF PIGMENT PREPARATION FROM PRESSCAKE

[0079] To 3088.5 g of presscake of diketopyrrolopyrrole-pigment (Hostaperm Red® D3G70) containing 42.8 wt-% dry pigment are added 129.1 g of Dispersogen® PTS and 52.5 g of water. This pigment dispersion is “pre-dispersed” using a high shear agitation apparatus (Dispermat, Getzmann, AE03) for 30 minutes at 2000 rpm and then milled using a bead mill apparatus (MiniCer, Netzsch) using Silibeads (0.6-0.8 mm) for 2 hours at 2000 rpm. The pigment has an average particle size (D50) of 0.17 micron.

EXAMPLE 2: FORMATION OF PIGMENT PREPARATION FROM PIGMENT POWDER

[0080] To 492.4 g of diketopyrrolopyrrole-pigment powder (Hostaperm® Red D3G70) are added 44.3 g of Dispersogen® PTS and 663.4 g of water. This pigment dispersion is “pre-dispersed” using a high shear agitation apparatus (Dispermat, Getzmann, AE03) for 30 minutes at 2000 rpm and then milled using a bead mill apparatus (MiniCer, Netzsch) using Silibeads (0.6-0.8 mm) for 2 hours at 2000 rpm. The pigment has an average particle size (D50) of 0.2 micron.

EXAMPLE 3

[0081] To 2000.0 g of pigment preparation of Example 1 is added 478.3 g of Baybond® PU 406 and 2.0 g of Dispersogen® PTS. After mixing for 1 hour at room temperature, the mixture is heated to 80° C. and stirred for 8 hours. After cooling down to room temperature a liquid dispersion of environmentally stable organic pigment is obtained. The product may be used as liquid dispersion (44.2 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 4 (COMPARATIVE EXAMPLE WITHOUT STABILIZATION)

[0082] To 2000.0 g of pigment preparation of Example 1 is added 2.0 g of Dispersogen® PTS. After mixing for 1 hour at room temperature, the mixture is stirrer for 8 hours at room temperature. The product may be used as liquid dispersion (42.4 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 5

[0083] The procedure of Example 3 is followed except that 673.6 g of Baybond® PU 406 is added to 1126.6 g Hostaperm® Red D3G70 pigment preparation containing 1.1 g Dispersogen® PTS. The environmentally stable organic pigment dispersion obtained after the heating/cooling cycle (as described in Example 3) may be used as liquid dispersion (41.5 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 6

[0084] To 415 g of pigment preparation of Example 2 is added 100.0 g of Baybond® PU 406 and 1.7 g of Dispersogen® PTS. After mixing for 10 min at room temperature, the mixture is heated to 80° C. and stirred for 2 hours. After cooling down to room temperature a liquid dispersion of environmentally stable organic pigment is obtained. The product may be used as liquid dispersion (43.4 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 7(COMPARATIVE EXAMPLE WITHOUT HEATING)

[0085] To 415 g of pigment preparation of Example 2 is added 100.0 g of Baybond® PU 406 and 1.7 g of Dispersogen® PTS. After mixing for 10 min at room temperature, the mixture is stirred for 2 hours at room temperature. The product may be used as liquid dispersion (42.4 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 8

[0086] To 950 g of pigment preparation of Example 2 is added 264.3 g of Takelac® W-6061 and 3.9 g of Dispersogen® PTS. After mixing for 10 min at room temperature, the mixture is heated to 80° C. and stirred for 2 hours. After cooling down to room temperature a liquid dispersion of environmentally stable organic pigment is obtained. The product may be used as liquid dispersion (42.0 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 9

[0087] To 950 g of pigment preparation of Example 2 is added 264.3 g of Takelac® W-5100 and 3.9 g of Dispersogen® PTS. After mixing for 10 min at room temperature, the mixture is heated to 80° C. and stirred for 2 hours. After cooling down to room temperature 250 g of water is added and a liquid dispersion of environmentally stable organic pigment is obtained. The product may be used as liquid dispersion (33.0 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 10

[0088] The procedure of Example 1 is followed except that 156.2 g of Chemipearl® S200 is added to 400.0 g Hostaperm® Red D3G70 pigment preparation containing 1.7 g Dispersogen® PTS. The product obtained after the heating for 2 hours at 80° C. and cooling down may be used as liquid dispersion (55.0 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

EXAMPLE 11

[0089] The procedure of Example 1 is followed except that 103.0 g of Chemipearl® V200 is added to 400.0 g Hostaperm® Red D3G70 pigment preparation containing 1.7 g Dispersogen® PTS. The product obtained after the heating for 2 hours at 80° C. and cooling down may be used as liquid dispersion (61.1 wt-% dry content) or dried for use in this form or it may be further treated by methods well known in the art.

TABLE-US-00001 TABLE 1 Properties of environmentally stable organic pigments Solid CS (in content Thermosan) D50 D90 Example (%) (%) (μm) (μm) Example 4 40.9 105.4 0.19 0.32 (Comparative example without stabilization) Example 7 42.4 82.5 2.60 5.45 (Comparative example without heating) Example 3 44.2 77.0 0.31 1.67 Example 5 41.5 65.7 1.20 4.49 Example 8 42.0 39.8 1.83 4.58 Example 9 33.0 41.2 1.48 2.55 Example 10 55.0 91.0 0.18 0.29 Example 11 61.1 93.4 0.18 0.30

[0090] Table 1 shows the results of the invented environmentally stable organic pigments. Due to the presence of the polymer on the surface of the pigment, the size increases (D50 and D90 values) and the colour strength decreases.

TABLE-US-00002 TABLE 2 Weather fastness results - Change in coloristic (dE) over time dE in Thermosan ® NQG (silicone paint) Example 500 h 1000 h 1500 h 2000 h Example 4 0.6 1.4 2.8 5.0 (Comparative example without stabilization) Example 7 0.4 1.6 3.4 5.7 (Comparative example without heating) Example 3 1.5 0.6 1.1 3.7 Example 5 1.7 1.0 0.9 2.8 Example 9 1.1 0.7 1.1 2.3

[0091] Table 2 clearly demonstrates the effect of the environmentally stabilized organic pigments compared to their unstabilized pigments comparative Example 4 (without polymer) and 7 (without heating step).

TABLE-US-00003 TABLE 3 Accelerated oxidation fastness results - Change in coloristic (CS and dE) over time Oxidation in Stucco di Luce 3 weeks 6 weeks Example CS (%) dE CS (%) dE Example 4 78 1.7 61 3.7 (Comparative example without stabilization) Example 7 83 1.4 69 3.1 (Comparative example without heating) Example 3 88 1.0 75 2.5 Example 5 86 1.3 82 2.4

[0092] Table 3 clearly demonstrates the effect of the environmentally stable organic pigments compared to their unstabilized pigments comparative Example 4 (without polymer) and 7 (without heating).

[0093] FIGS. 1 and 2 show the different rheological behaviours of samples with (Example 6) and without heating (comparative Example 7), respectively. Samples, which are pure mixtures of pigments and polymer dispersion without the heating step exhibit a much higher viscosity and show shear thinning behaviour. Samples of the invented environmental stable organic pigments exhibit lower comparative viscosities at the same shear rate and do not show shear thinning behaviour.

[0094] Instruments

[0095] Pigment preparations were obtained by predispersing pigments using high shear agitation apparatus Dispermat AE03 (Getzmann) followed by milling using a bead mill apparatus MiniCer (Netzsch) using Silibeads (0.6-0.8 mm).

[0096] Particle size distribution were measured on a Malvern Mastersizer 2000, where the distribution is determined by the D-Values D50 and D90, which are the intercepts for 50% and 90% of the cumulative mass.

[0097] The rheological properties were measured on a Malvern Kinexus Pro equipped with a plate-plate configuration at 25° C. The diameter of the plates was 50 mm and the measuring gap was 1 mm. The measurement was carried out in five steps: [0098] 1. Shear rate: 100 s.sup.−1 for 300 s (shearing) [0099] 2. Shear rate: 0 s.sup.−1 for 300 s (resting) [0100] 3. Shear rate: 100 s.sup.−1 for 300 s (shearing) [0101] 4. Shear rate: 0 s.sup.−1 for 300 s (resting) [0102] 5. Shear rate: 100 s.sup.−1 for 300 s (shearing)

[0103] Determination of Colour Strength

[0104] All the samples are tested in a silicone based coating (Thermosan NQG, DAW) and their colour strength is compared to a standard. The standard corresponds to a commercial product (Colanyl® Red D3GD 500, Clariant) containing the same pigment as in the Examples 1-11, whereby the pigment is not stabilized by a polymer. Each pigment preparation (Examples 1-11), as well as the standard, is then mixed with Thermosan NQG in a way that the final coloured coating has a pigment content of 0.5% by weight. Mixing is achieved for 3 minutes at 3500 rpm using a SpeedMixer™ (DAC 150.1 FVZ, Hauschild Engineering). The coloured coating is then applied on a test card (Chromolux® 200) using a film applicator with 200 μm gap height (RK K Control Coater, Erichsen). The test card is then dried at 40° C. for approximatively 25 minutes and then at room temperature for 40 minutes. When the coating is dried on the card, the colour strength is then measured in comparison to Colanyl® Red D3GD 500 using a colorimeter (Datacolor® remission spectrophotometer Spectraflash SF 600 PLUS CT, Datacolor International).

[0105] Weather Fastness Test

[0106] The accelerated weather is carried out in accordance with DIN EN ISO 11341. ⅓ and 1/25 of standard depth are considered for the weather fastness tests performed using a silicon based coating (Thermosan® NQG). For instance 1/25 standard depth means that 1 part of coloured pigment preparations must be mixed with the necessary amount of Thermosan® NQG to reach 1/25 of the depth of a defined standard (Colanyl® Red D3GD 500). When the right dosage is found, the coloured coating is then applied onto a weather fastness plaque and put in the Ci5000 Weather-Ometer® (Atlas) for at least 2000 hours following the standard weather fastness circle ISO 16474-2 (Paints and varnishes—Methods of exposure to laboratory light sources—Part 2: Xenon-arc lamps). All the changes in coloristic (dE) are measured over time using a colorimeter (Datacolor® remission spectrophotometer Spectraflash SF 600 PLUS CT, Datacolor international) and summarised in Table 2.

[0107] Accelerated Oxidation Fastness

[0108] A spackling paste (Stucco Di Luce) is chosen for its extreme oxidative character to assess the resistance against oxidation of the environmentally stable organic pigments contained in Examples 1-11 compared to the unprotected pigment contained in the standard (Colanyl® Red D3GD 500, Clariant). Each pigment preparation (Examples 1-11), as well as the standard, is then mixed with StuccoDecor Di Luce in a way that the final coloured coating has a pigment content of 1.5% by weight. Mixing is achieved for 2 minutes at 3000 rpm using a SpeedMixer™ (DAC 150.1 FVZ, Hauschild Engineering). The coloured coating is applied onto a card using a film applicator with 200 μm gap height (RK K Control Coater, Erichsen) and dried at room temperature. The card are placed in an oven dryer at 50° C. for 6 weeks. All the changes in coloristic (dE) and colour strength are measured after 3 and 6 weeks using a colorimeter (Datacolor® remission spectrophotometer Spectraflash SF 600 PLUS CT, Datacolor International) and summarised in the Table 3

[0109] Chemicals and Materials

[0110] Hostaperm® Red D3G 70 press cake—Clariant Plastics & Coatings (Germany) GmbH

[0111] Hostaperm® Red D3G 70 powder—Clariant Plastics & Coatings (Germany) GmbH

[0112] Colanyl® Red D3GD 500—Clariant Plastics & Coatings (Germany) GmbH Dispersogen® PTS—Clariant Products (Germany) GmbH is a nonionic, surfactant based dispersing agent for water-based pigment preparations, suitable for organic pigments and carbon blacks.

[0113] Baybond® PU 406—Covestro AG (PU dispersion)

[0114] Takelac® W-6061—Mitsui Chemicals, Inc. (PU dispersion)

[0115] Takelac® WS-5100—Mitsui Chemicals, Inc. (PU dispersion)

[0116] Takelac® WBP-341—Mitsui Chemicals, Inc. (PU dispersion)

[0117] Chemipearl® S200—Mitsui Chemicals, Inc. (Ionomer dispersion)

[0118] Chemipearl® V200—Mitsui Chemicals, Inc. (Non-ionic dispersion)

[0119] Thermosan® NQG—CAPAROL Farben Lacke Bautenschutz GmbH (silicone paint)

[0120] Capadecor StuccoDecor Di Luce (Stucco di Luce)—CAPAROL Farben Lacke Bautenschutz GmbH

LIST OF ABBREVIATIONS

[0121] dE Delta E (according to CIELAB coding and defined by DIN EN ISO 11664-4) [0122] CIE International Commission on Illumination [0123] CS colour strength [0124] UV ultra violet [0125] PU polyurethane [0126] NCO isocyanate [0127] IPDI isophorone diisocyanate [0128] IPDA isophorone diamine [0129] Mn number average molecular weight [0130] D50 average particle size determined by the D-Values D50, which is the intercepts for 50% of the cumulative mass [0131] D90 average particle size determined by the D-Values D90, which is the intercepts for 90% of the cumulative mass