Hydrophobically modified polyisocyanurate plastic and method for production thereof

Abstract

The invention relates to novel modified polyisocyanurate plastics, obtainable by means of catalytic trimerization of a composition (A), wherein the composition (A) contains oligomeric, modified polyisocyanates (B), which represent a reaction product from an oligomeric polyisocyanate (B1) and at least one functionalization reagent (B2) which is reactive to isocyanate groups, wherein the composition (A) comprises a content of monomeric diisocyanates of 20 wt % at maximum and wherein the at least one functionalization reagent (B2) which is reactive to isocyanate groups has at least one relative functional group which is reactive to isocyanate groups and which is not an isocyanate group. The invention further relates to the method by which the polyisocyanurate plastics according to the invention are obtainable, to the use of the polyisocyanurate plastics according to the invention for producing coatings, films, semi-finished products, composite materials and molded parts, and substrates coated by such a coating.

Claims

1. A modified polyisocyanurate plastic obtained by a process comprising the steps of: a1) providing a composition A), containing oligomeric, modified polyisocyanates B) and not more than 20% by weight of monomeric diisocyanates based on the weight of the composition A), wherein the oligomeric modified polyisocyanates B) constitute a reaction product of an oligomeric polyisocyanate B1) and at least one isocyanate-reactive functionalization reagent B2), and wherein the at least one isocyanate-reactive functionalization reagent B2) comprises at least one isocyanate-reactive functional group which is not an isocyanate group, and wherein the at least one isocyanate-reactive functionalization reagent B2) after reaction with polyisocyanate B1) lowers the surface energy of the polyisocyanurate plastic by at least 2 mN/m; (a2) catalytic trimerization of the composition A), wherein the modified polyisocyanurate plastic is a solid, transparent and bubble-free molding.

2. The modified polyisocyanurate plastic as claimed in claim 1, wherein the at least one isocyanate-reactive functionalization reagent B2) has a surface tension of <20 mN/m.

3. The modified polyisocyanurate plastic as claimed in claim 1, wherein the at least one isocyanate-reactive functionalization reagent B2) is an alcohol.

4. The modified polyisocyanurate plastic as claimed in claim 1, wherein an oligomeric, modified polyisocyanate B) of an oligomeric structure is used as oligomeric, modified polyisocyante B), wherein the oligomeric structure is chosen from uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structure.

5. The modified polyisocyanurate plastic as claimed in claim 1, wherein the oligomeric polyisocyanate B1) is constructed on the basis of 1,5-diisocyanatopentane (PDI), 1,6-diisocyanatohexane (HDI), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 2,4′-diisocyanatodicyclohexylmethane or 4,4′-diisocyanatodicyclohexylmethane (H12MDI) or mixtures thereof.

6. The modified polyisocyanurate plastic as claimed in claim 1, wherein the catalytic trimerization is carried out in the presence of a trimerization catalyst C), wherein the trimerization catalyst C) comprises at least one alkali metal or alkaline earth metal salt.

7. The modified polyisocyanurate plastic as claimed in claim 6, wherein the trimerization catalyst C) comprises potassium acetate as the alkali metal salt.

8. The modified polyisocyanurate plastic as claimed in claim 6, wherein the trimerization catalyst C) comprises a polyether.

9. The modified polyisocyanurate plastic as claimed in claim 1, wherein the composition A) has a content of monomeric diisocyanate of not more than 15% by weight, not more than 10% by weight or not more than 5% by weight, based in each case on the weight of the composition A).

10. The modified polyisocyanurate plastic as claimed in claim 1, wherein it constitutes a highly converted modified polyisocyanurate plastic in which not more than 20% of the isocyanate groups originally contained in the composition A) have been preserved.

11. A process for producing a modified polyisocyanurate plastic solid, transparent and bubble-free body, comprising the steps of: a1) providing a composition A), containing oligomeric, modified polyisocyanates B) and not more than 20% by weight of monomeric diisocyanates based on the weight of the composition A), wherein the oligomeric modified polyisocyanates B) constitute a reaction product of an oligomeric polyisocyanate B1) and at least one isocyanate-reactive functionalization reagent B2), and wherein the at least one isocyanate-reactive functionalization reagent B2) comprises at least one isocyanate-reactive functional group which is not an isocyanate group, and wherein the at least one isocyanate-reactive functionalization reagent B2) after reaction with polyisocyanate B1) lowers the surface energy of the polyisocyanurate plastic by at least 2 mN/m; a2) catalytic trimerization of the composition A), wherein the solid, transparent and bubble-free body is a molding.

12. The process as claimed in claim 11, wherein the oligomeric polyisocyanate B1) is constructed on the basis of 1,5-diisocyanatopentane (PDI), 1,6-diisocyanatohexane (HDI), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 2,4′-diisocyanatodicyclohexylmethane or 4,4′-diisocyanatodicyclohexylmethane (H12MDI) or mixtures thereof, wherein the at least one isocyanate-reactive functionalization reagent B2) has a surface tension of <20 mN/m and/or wherein the composition A) has a content of monomeric diisocyanate of not more than 15% by weight, not more than 10% by weight or not more than 5% by weight, based in each case on the weight of the composition A).

13. The process as claimed in claim 11, wherein the catalytic trimerization is continued at least up to a degree of conversion at which only not more than 20% of the isocyanate groups originally contained in the composition A) remain present, so that a highly converted modified polyisocyanurate plastic is obtained.

Description

EXAMPLES

(1) All reported percentages are based on weight unless otherwise stated.

(2) The NCO contents are determined by titrimetry in accordance with DIN EN ISO 11909.

(3) The residual monomer contents are measured in accordance with DIN EN ISO 10283 by gas chromatography with an internal standard.

(4) All the viscosity measurements are made with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (Germany) to DIN EN ISO 3219.

(5) The densities of the starting polyisocyanates are determined to DIN EN ISO 2811, and those of the cured polyisocyanurate plastics to DIN EN ISO 1183-1.

(6) The contents (mol %) of the uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structures present in the starting polyisocyanates are calculated from the integrals of proton-decoupled .sup.13C NMR spectra (recorded on a Bruker DPX-400 instrument) and are each based on the sum total of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structures present. In the case of HDI polyisocyanates, the individual structural elements have the following chemical shifts (in ppm): uretdione: 157.1; isocyanurate: 148.4; allophanate: 155.7 and 153.8, biuret: 155.5; iminooxadiazinedione: 147.8, 144.3 and 135.3; oxadiazinetrione: 147.8 and 143.9.

(7) The glass transition temperature Tg is determined by means of DSC (differential scanning calorimetry) with a Perkin Elmer DSC-7 in accordance with DIN EN 61006. Calibration is effected via the melt onset temperature of indium and lead. 10 mg of substance are weighed out in standard capsules. The measurement is 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 is effected by means of liquid nitrogen. The purge gas used is nitrogen. The values stated in the table below are based in each case on the evaluation of the 3rd heating curve. The glass transition temperature Tg determined is the temperature at half the height of a glass transition step.

(8) Shore hardnesses are measured to DIN 53505 with the aid of a Zwick 3100 Shore hardness tester (from Zwick, Germany).

(9) IR spectra is recorded on a Spectrum Two FT-IR spectrometer equipped with an ATR unit, from Perkin Elmer, Inc.

(10) Water absorption of the test specimens is determined by gravimetric means after seven-day storage in water at 23° C.

(11) Contact angle, surface tension and surface energy are determined at 23° C. with an OCA 20 contact angle measuring instrument from Dataphysics GmbH.

(12) All further raw materials were, unless otherwise described, obtained from Sigma-Aldrich in analytical quality.

(13) Starting Compounds

(14) Oligomeric Starting Polyisocyanate B1)-1

(15) For use as polyisocyanate composition A), the starting polyisocyanate A1) prepared is an HDI polyisocyanate containing isocyanurate groups, prepared in accordance with Example 11 of EP-A 330 966. The reaction is stopped at an NCO content of the crude mixture of 40% by addition of dibutyl phosphate. Subsequently, unconverted HDI is removed by thin-film distillation at a temperature of 130° C. and a pressure of 0.2 mbar.

(16) NCO content: 21.8%

(17) NCO functionality: 3.4

(18) Monomeric HDI: 0.1%

(19) Viscosity (23° C.): 3000 mPas

(20) Density (20° C.): 1.17 g/cm.sup.3

(21) Distribution of the Oligomeric Structure Types:

(22) Isocyanurate: 84.5 mol %

(23) Iminooxadiazinedione 5.4 mol %

(24) Uretdione 2.9 mol %

(25) Allophanate: 7.2 mol %

(26) Oligomeric, Modified Polyisocyanate (B)-1

(27) 870 g (4.51 val) of the oligomeric starting polyisocyanate B1)-1 are admixed with 50 g of dodecanol at room temperature with stirring and subsequently heated to 50° C. for 3 h. After cooling to room temperature and further stirring for 12 h a clear, oligomeric, modified polyisocyanate is obtained.

(28) Oligomeric, Modified Polyisocyanate (B)-2

(29) 870 g (4.51 val) of the oligomeric starting polyisocyanate B1)-1 are admixed with 50 g of perfluoroheptanol at room temperature with stirring and subsequently heated to 50° C. for 3 h. After cooling to room temperature and further stirring for 12 h a clear, oligomeric, modified polyisocyanate is obtained.

(30) Catalyst Mixture C)-1

(31) To produce the catalyst 159.058 g of diethylene glycol are mixed with 24.588 g of 18-crown-6 and 7.557 g of potassium acetate and stirred at room temperature until a homogeneous solution is formed.

(32) Production of the Inventive Examples:

(33) 120 g of the starting polyisocyanate (B)-1 and (B)-2 are weighed into a polypropylene cup together with 3.7 g of the catalyst mixture C)-1 and homogenized at 3500 rpm for 1 min using a DAC 150 FVZ Speed-Mixer (Hauschild, Germany). 12 g of the obtained mixture are poured into an aluminum dish having a diameter of 9.7 cm and subsequently cured at 180° C. for 15 minutes in an oven.

(34) Production of the Noninventive Example:

(35) 120 g of the starting polyisocyanate (B)-1 are weighed into a polypropylene cup together with 3.7 g of the catalyst mixture C)-1 and homogenized at 3500 rpm for 1 min using a DAC 150 FVZ Speed-Mixer (Hauschild, Germany). 12 g of the obtained mixture are poured into an aluminum dish having a diameter of 9.7 cm and subsequently cured at 180° C. for 15 minutes in an oven.

(36) TABLE-US-00001 Batches: (B)-1 + C)-1 (B)-2 + C)-1 B1)-1 + C)-1 Shore hardness D 75 44 77 Tg (DSC) 1.sup.st heating 82 34 106 Contact angle 91 46 40 (sample underside)

(37) Viscosity is determined from the obtained modified polyisocyanurates and surface composition, hardness, Tg and surface tension are determined from the obtained cured polymers. The results show a distinct hydrophobization of the polyisocyanurates modified and cured in accordance with the invention. At the same time glass transition temperature and hardness are reduced. Analysis of the surfaces by FT IR spectroscopy shows a distinct change in the surface IR spectrum compared to the starting compound. The hydrophobically modified isocyanurate compounds are concentrated at the surface of the plastic (see the CF vibration in the IR of sample ((B)-2+C)-1) at 1230 cm.sup.−1 and the higher intensity of the CH stretching vibration of ((B)-1+C)-1) in the IR at 2950 cm.sup.−1. This achieves a higher resistance and insensitivity in particular to hydrophilic impurities such as water and alcohols and also to polar solvents such as acetone, as is discernible from the increasing contact angle of the inventive examples.