Mixtures of coated pigments and fatty acid salts for dyeing PVC

Abstract

The present invention relates to mixtures of pigments comprising at least one inorganic compound selected from the group of iron oxides, iron oxide hydrates, zinc ferrites, zinc oxides, magnesium ferrites and manganese ferrites, wherein the at least one inorganic compound is equipped with a coating comprising at least one hydroxide or oxide of magnesium or calcium and at least one calcium salt or magnesium salt of a fatty acid, to processes for production thereof, to the use thereof for coloring polyvinyl chloride (PVC) and to processes for coloring PVC and to PVC colored with such mixtures, and also to plastics products comprising such mixtures.

Claims

1. A mixture comprising: at least one coated pigment comprising at least one inorganic compound selected from the group consisting of iron oxides, iron oxide hydroxides, zinc ferrites, zinc oxides, magnesium ferrites and manganese ferrites, wherein the at least one inorganic compound comprises a coating comprising at least one hydroxide or oxide of magnesium and optionally at least one hydroxide or oxide of calcium, whereby the coated pigment comprises 0.3% to 30% by weight of magnesium, and may include traces of calcium to provide a calcium content of 0.1% by weight or less, and at least one calcium salt and/or magnesium salt of a fatty acid of the general formulae C.sub.nH.sub.2n+1COOH (I), C.sub.nH.sub.2n1COOH (II), C.sub.nH.sub.2n3COOH (III) and/or C.sub.nH.sub.2n5COOH (IV), where n is 10 to 20.

2. The mixture as claimed in claim 1, wherein the coating does not include hydroxides or oxides of calcium.

3. The mixture as claimed in claim 1, wherein the coating is bonded directly to the at least one inorganic compound, and the coated pigment comprises 0.5 wt % to 30 wt % of magnesium and 0.001 wt % to 0.1 wt % of calcium.

4. The mixture as claimed in claim 1, wherein the mixture comprises a combined total of 0.3% to 30% by weight of magnesium and calcium, calculated as the sum total of the contents of the elements magnesium and calcium, where the sum total of the contents of the elements magnesium and calcium is based on the total weight of the mixture.

5. The mixture as claimed in claim 1, wherein the mixture comprises 0.2% to 15% by weight of the at the least one calcium salt and/or magnesium salt of a fatty acid.

6. The mixture as claimed in claim 1, wherein n is 15 to 19.

7. The mixture as claimed in claim 6, wherein: the coating is bonded directly to the at least one inorganic compound; the mixture comprises 0.3% to 30% by weight combined total of magnesium and calcium, calculated as the sum total of the contents of the elements magnesium and calcium, where the sum total of the contents of the elements magnesium and calcium is based on the total weight of the mixture; and the mixture comprises 0.2% to 15% by weight of at the least one calcium salt and/or magnesium salt of a fatty acid.

8. The mixture as claimed in claim 7, wherein: the coating comprises only the at least one hydroxide and/or oxide of magnesium and no oxides or hydroxides of calcium; the coated pigment comprises 0.5 to 20 wt % magnesium and may contain 0.001 to 0.1 wt % calcium; the mixture comprises 1% to 20% by weight combined total of magnesium and calcium, calculated as the sum total of the contents of the elements magnesium and calcium, where the sum total of the contents of the elements magnesium and calcium is based on the total weight of the mixture; and the at least one calcium salt and/or magnesium salt comprises calcium stearate and/or magnesium stearate.

9. A process for producing the mixture as claimed in claim 1, the process comprising: forming an aqueous suspension of the at least one inorganic compound; precipitating the coating onto the inorganic compound by at least one of: adding magnesium salts and optionally calcium salts to the suspension, and then adding a precipitant selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and ammonia to the suspension to form coated pigment; or adding a precipitant selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and ammonia to the suspension, and then adding magnesium salts and optionally calcium salts to the suspension to form the coated pigment; at least one of: isolating the coated pigment, washing the coated pigment, drying the coated pigment, and comminuting the coated pigment to provide a processed coated pigment; and mixing the processed coated pigment with the at least one calcium salt and/or magnesium salt of a fatty acid at a temperature of 10 to 40 C. to form the mixture.

10. The process for producing the mixture as claimed in claim 9, wherein the process does not include a calcination step.

11. A plastics product comprising: the mixture as claimed in claim 1, and at least one polymer, where at least 50% by weight of the polymer is formed from monomers of vinyl chloride, wherein the aforementioned components add up to 40% to 100% by weight, based on the total weight of the plastics product.

12. The plastics product as claimed in claim 11, wherein the plastics product comprises 10% to 90% by weight of the mixture.

13. The plastics product as claimed in claim 11, further comprising 0% to 15% by weight of plasticizer based on the amount of polymer present in the plastics product.

14. The plastics product as claimed in claim 11, wherein the polymer is pulverulent and the plastics product comprises a mixture of the pulverulent polymer and the mixture.

15. A product comprising at least one plastics product as claimed in claim 11.

16. The product as claimed in claim 15, wherein the product comprises window profiles, pipes, floor coverings, insulation material or roofing sheets.

17. A process for producing the plastics products as claimed in claim 11, the process comprising kneading or extruding the polymer with the mixture.

18. A process for producing the plastics product as claimed in claim 14, the process comprising mixing the mixture and pulverulent polyvinyl chloride, by mixing the constituents at a temperature of 0.5 to 20 K below the melting point of the polyvinyl chloride.

19. A method of coloring polyvinyl chloride, the method comprising mixing the mixture as claimed in claim 1 with polyvinyl chloride.

Description

EXAMPLES AND METHODS

I. Description of the Measurement and Test Methods Used

(1) The results of the measurements for the examples are summarized in Table 1.

(2) I.1 Mg and Ca Determination

(3) The magnesium and calcium content of the pigments was measured via optical emission spectrometry after excitation in an inductively coupled plasma (ICP-OES: inductively coupled plasma-optical emission spectrometry) as the content of elements.

(4) I.2 Oil Value

(5) The oil value was determined according to standard DIN ISO 787/5 in g of oil/100 g of sample. Sample means either the pigment or the mixture.

(6) I.3 Testing of PVC Stability by Means of Thermo Haake Rheomix 600p Kneader (Kneader Stability)

(7) A pulverulent PVC mixture consisting of 50% by weight of Vestolit B 7021 Ultra+50% by weight of SorVyl DB 6888 Natur 3/03 is mixed homogeneously with the mixture to be tested (4% by weight based on 100% PVC composition).

(8) A pulverulent PVC mixture consisting of 50% by weight of Vestolit B 7021 Ultra+50% by weight of SorVyl DB 8688 Natur 3/03 is mixed homogeneously with the pulverulent pigment sample to be tested (4% by weight based on 100% PVC composition) or the mixture to be tested.

(9) The pigmented PVC mixture is introduced manually into the recording kneader (Thermo Haake Rheomix 600p with R6 roll rotors) which has been preheated to 190 C. and is equipped with a rotary rheometer. The recording program (PolyLab Monitor) is started and records the torque on the roll rotors and the temperature of the sample against time. The pigmented PVC mixture is kneaded at 190 C. and 50 rpm. In order to determine the suitability of the mixture with regard to the stabilization of PVC, the maximum torque on the time axis in minutes at which the highest product temperature was measured is reported. After this maximum torque, the torque declines significantly, since the PVC breaks down to an increasing degree after this time and the viscosity of the kneaded product decreases as a result. These values are compared with the corresponding value for the same, albeit uncoated, pigment powder. The longer the period of time until said maximum, the higher the stability of the PVC colored with the mixture.

II. Examples

II.1 Properties of the Inorganic Pigments and Plastics Used

(10) Bayferrox 110 pigment powder from LANXESS Deutschland GmbH: hematite (red iron oxide, -Fe2O3) having a BET surface area to DIN ISO 9277 of 13-18 m.sup.2/g.

(11) Bayferrox 920: goethite, -FeOOH paste from LANXESS Deutschland GmbH, from which Bayferrox 920 powder is produced by drying and grinding. The pulverulent pigment has a BET surface area to DIN ISO 9277 of 11-15 m.sup.2/g. Alternatively, it is also possible to mix the pulverulent Bayferrox 920 pigment with water to give a slurry having the appropriate pigment concentration (see examples).

(12) Calcium stearate: Powder from VWR BDH PROLABO with Ca content between 9% and 11% by weight (calculated as CaO).

(13) SorVyl DB 668 Natur 3/03: Rigid PVC compound from Polymerchemie (powder form, stabilized with Ca/Zn, where the content of bis(pentane-2,4-dionato)calcium is less than 1% by weight, with softening point >120 C., flashpoint >190 C., ignition temperature >300 C., density to DIN EN ISO 1183-1 method A, of 1.39 g/cm.sup.3, bulk density to DIN EN ISO 60 of 0.54 g/ml, thermal stability to DIN EN 60811-3-2 of greater than/equal to 25 min.).

(14) VESTOLIT B 7021 Ultra: Mikro-S-PVC homopolymer from Vestolit (powder form, K value to DIN EN ISO 1628-2 of 70, viscosity number to DIN EN ISO 1628-2 of 125 cm.sup.3/g, bulk density to DIN EN ISO 60 of 0.3 g/cm.sup.3, sieve analysisresidue on 0.063 mm sieve to DIN EN ISO 1624 of <1%, water content according to K. Fischer DIN 53 715 of 0.3%, pH of the aqueous extract to DIN EN ISO 1284 of 8, 1.5/s paste viscosity of 1.8 Pa s 45/s paste viscosity of 2.2 Pa s).

II.2 Inventive Examples and Comparative Examples

Example 1 (Comparative Example)

(15) 145.6 g of Bayferrox 110 pigment and 4.5 g of calcium stearate were added to the Henschel FM4 mixer (from Thyssen Henschel). The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

Example 2 (Comparative Example)

(16) 141 g of Bayferrox 110 pigment and 9 g of calcium stearate were added to the Henschel FM4 mixer. The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

Starting Material for Examples 3 and 4

(17) To 3.3 dm.sup.3 of aqueous suspension of Bayferrox 110 (8.28 mol of Fe.sub.2O.sub.3 having a pH of 4.8 were added, at 60 C. while stirring, 1443 ml of an MgSO.sub.4 solution (corresponding to 2.58 mol/dm.sup.3 of MgO). Subsequently, 3.98 mol of NaOH per mole of Fe.sub.2O.sub.3 were added dropwise as a solution while stirring within 30 min. (2215 g with concentration 16.6 mol/dm.sup.3). The suspension was stirred for a further 60 min. The pH of the suspension was >11. After the reaction had ended, the pigment was filtered through a suction filter, washed until the conductivity of the filtrate was below 300 S/cm, dried to constant weight in a drying cabinet at 120 C. and ground in a Bauermeister mill (cross-beater mill with a sieve insert, mesh size 1 mm).

Example 3

(18) 145.5 g of pigment starting material 1 and 4.5 g of calcium stearate were added to the Henschel FM4 mixer. The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

Example 4

(19) 141 g of pigment (starting material 1) and 9 g of calcium stearate ware added to the Henschel FM4 mixer. The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

Example 5 (Comparative Example)

(20) 145.5 g of Bayferrox 920 pigment powder and 4.5 g of calcium stearate were added to the Henschel FM4 mixer. The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

Starting Material 2 for Examples 6 and 7

(21) To 2.05 dm.sup.3 of aqueous suspension of Bayferrox 920 (5.83 mol of FeOOH) having a pH of 4 were added, at 60 C. while stirring, 3571 ml of an MgSO.sub.4 solution (1.39 mol/dm.sup.3 as MgO). Subsequently, 1.41 mol of NaOH per mole of FeOOH are added dropwise as a solution while stirring within 15 min. (1283 g with concentration 7.87 mol/dm.sup.3). The suspension was stirred for a further 60 min. The pH of the suspension was about 10. After the reaction had ended, the pigment was filtered through a suction filter, washed until the conductivity of the filtrate was below 300 S/cm, dried to constant weight in a drying cabinet at 120 C. and ground in a Bauermeister mill (cross-beater mill with a sieve insert, mesh size 1 mm).

Example 6 (Inventive)

(22) 145.5 g of pigment (starting material 2) and 4.5 g of calcium stearate were added to the Henschel FM4 mixer. The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

Example 7 (Inventive)

(23) 141 g of pigment (starting material 2) and 9 g of calcium stearate were added to the Henschel FM4 mixer. The two substances were mixed together at room temperature (20 to 25 C.) and 1000 rpm for 20 min. The pulverulent product is used for the testing without further treatment.

(24) The properties of the products are compiled in table 1.

(25) TABLE-US-00001 TABLE 1 Calcium Oil value stearate (g of oil/ Kneader Mg content content 100 g of stability Example (% by wt.) (% by wt.) sample) (min.) Bayferrox 0.01 0 24.8 14 110 .sup.a) 1 0.01 3 24.1 14 2 0.01 6 24.1 14 3 7.6 3 28.3 19 4 7.4 6 28.2 20 Bayferrox 0.02 0 27.6 13 920 .sup.b) 5 0.02 3 28.0 13 6 14.0 3 38.3 19 7 13.6 6 33.3 20 .sup.a) uncoated pigment as direct comparison with examples 1 to 4, .sup.b) uncoated pigment as direct comparison with examples 5 to 7.