COLOURED PLASTICS BASED ON CROSSLINKED POLYISOCYANATES

Abstract

The invention relates to materials made from cross-linked isocyanates which are coloured by pigments and/or pigment formulations.

Claims

1.-9. (canceled)

10. A colored plastic obtained by the catalytic crosslinking of a polyisocyanate composition A in the presence of at least one pigment, wherein (i) the plastic contains at least 5% by weight of a fibrous filler having an aspect ratio of at least 100, based on the sum total of the weights of polyisocyanate composition A, dye and fibrous filler; and (ii) the nitrogen components bound within uretdione, isocyanurate, biuret and iminooxadiazinedione structures add up to at least 60% of the total nitrogen content of the polyisocyanate composition A.

11. The colored plastic as claimed in claim 10, wherein at least 8% by weight of the carbon present in the polyisocyanate composition A is bound within isocyanurate groups.

12. The colored plastic as claimed in claim 10, wherein the ratio of the sum total of all carbon atoms bound within isocyanurate and iminooxadiazinedione groups and the sum total of all carbon atoms bound within urethanes, allophanates, thiols, thiourethanes, thioallophanates, ureas and biurets in the cured polymer matrix of the composite material of the invention is between 500 and 1.

13. The colored plastic as claimed in claim 10, wherein the pigment is carbon black or zinc sulfide.

14. The colored plastic as claimed in claim 10 having a glass transition point the glass transition point of the uncolored plastic based on crosslinked polyisocyanates.

15. The colored plastic as claimed in claim 10 having a density the density of the uncolored plastic based on crosslinked polyisocyanates.

16. The colored plastic as claimed in claim 10, wherein the plastic includes the pigment in an amount within a range from 0.05% to 20% by weight, based on the total weight of the colored plastic.

17. A shaped body produced from the colored plastic as claimed in claim 10.

18. A process for producing a colored plastic based on crosslinked polyisocyanates, comprising the process steps of a) mixing the polyisocyanate composition A with at least one pigment, at least one fibrous filler having an aspect ratio of at least 100 and at least one crosslinking catalyst; and b) catalytically crosslinking the polyisocyanate composition A to give the colored plastic, wherein, at the end of the catalytic crosslinking, the nitrogen components bound within uretdione, isocyanurate, biuret and iminooxadiazinedione structures add up to at least 60% of the total nitrogen content of the polyisocyanate composition A.

Description

EXAMPLES

General Details:

[0118] In the examples, all percentages are to be understood as meaning percent by weight, unless otherwise stated.

[0119] The ambient temperature of 23 C. at the time of performance of the experiments is referred to as RT (room temperature).

Test Methods:

[0120] The methods detailed hereinafter for determination of the appropriate parameters were used for performance and evaluation of the examples and are also the methods for determination of the parameters of relevance in accordance with the invention in general.

Determination of Phase Transitions by DSC:

[0121] The phase transitions were determined by means of DSC (differential scanning calorimetry) with a Mettler DSC 12E (Mettler Toledo GmbH, Giessen, Germany) in accordance with DIN EN 61006. Calibration was effected via the melt onset temperature of indium and lead. 10 mg of substance were weighed out in standard capsules. The measurement was effected by three heating runs from 50 C. to +200 C. at a heating rate of 20 K/min with subsequent cooling at a cooling rate of 320 K/min. Cooling was effected by means of liquid nitrogen. The purge gas used was nitrogen. The values reported are each based on the evaluation of the 1st heating curve, since changes in the sample in the measurement process at high temperatures are possible in the reactive systems being examined as a result of the thermal stress in the DSC. The melting temperatures T.sub.m were obtained from the temperatures at the maxima of the heat flow curves. The glass transition temperature T.sub.g was obtained from the temperature at half the height of a glass transition step.

Determination of Infrared Spectra:

[0122] The infrared spectra were measured on a Bruker FT-IR spectrometer equipped with an ATR unit.

Starting Compounds:

[0123] Polyisocyanate A1: Desmodur N 3600 is an HDI trimer (NCO functionality >3) with an NCO content of 23.0% by weight from Covestro Deutschland AG. The viscosity is about 1200 mPas at 23 C. (DIN EN ISO 3219/A.3). Before use, the material was degassed under reduced pressure.

[0124] Polyethylene glycol (PEG) 400 was sourced from ACROS with a purity of >99% by weight and dried before use and degassed under reduced pressure.

[0125] Potassium acetate was sourced with a purity of >99% by weight from ACROS.

[0126] Dyes used were the following substances: [0127] carbon black (Printex G from Orion Engineered Carbons) [0128] organic dyes (Makrolex Green 5B from Lanxess), an anthraquinone dye [0129] zinc sulfide in carrier medium (UPL-10478 from Chromaflo)

Preparation of Catalyst Solution K1:

[0130] Potassium acetate (5.0 g) was stirred in PEG 400 (95.0 g) at RT until all of it had dissolved. In this way, a 5% by weight solution of potassium acetate in PEG 400 (K1) was obtained and was used as trimerization catalyst without further treatment.

Production of the Color Paste:

[0131] 25 g in each case of the dyes was added to 75 g of polyisocyanate Al and dispersed in a Speedmixer DAC 150.1 FVZ from Hauschild at 2750 min-1 for 5 min. UPL-10478 was used as obtained without dispersion in polyisocyanate Al.

Production of the Colored Polyisocyanurates:

[0132] The reaction mixture was prepared by mixing 38.4 g of polyisocyanate Al with 1.6 g of the catalyst solution at 23 C. for 3 min in a Speedmixer DAC 150.1 FVZ from Hauschild at 2750 min1. This was then admixed with an appropriate amount of color paste, poured into a suitable mold for crosslinking and then crosslinked in an oven at 180 C. for 5 min.

Working Example 1

[0133] As described above, 40 g of the reaction mixture was admixed with 2 g of a color paste based on Printex G and polyisocyanate Al and cured in an oven. This gave a homogeneous, black-colored plastic having a glass transition temperature of about 100 C. The conversion was >90% (determined by IR spectroscopy, decrease in the NCO band at 2270 cm-1).

Working Example 2

[0134] As described above, 40 g of the reaction mixture was admixed with 2 g of a color paste based on Makrolex Green 5B and polyisocyanate Al and cured in an oven. This gave a homogeneous, green-colored plastic having a glass transition temperature of about 100 C. The conversion was >90% (determined by IR spectroscopy, decrease in the NCO band at 2270 cm1).

Working Example 3

[0135] As described above, 40 g of the reaction mixture was admixed with 2 g of the color paste UPL-10478 and cured in an oven. This gave a homogeneous, white-colored plastic having a glass transition temperature T.sub.g of about 95 C. The conversion was >90% (determined by IR spectroscopy, decrease in the NCO band at 2270 cm1).