PROCESS FOR PRODUCING POLYISOCVANURATE PLASTICS HAVING FUNCTIONALIZED SURFACES

Abstract

The invention relates to a process for producing polyisocyanurate plastics having a functionalized surface, comprising the following steps: a) providing a polyisocyanate composition A) containing monomeric and/or oligomeric polyisocyanates; b) catalytically trimerizing the polyisocyanate composition A) so as to obtain a bulk polyisocyanurate material as intermediate; c) surface functionalizing the intermediate by contacting at least one surface of the intermediate with at least one functionalizing reagent D); d) continuing the catalytic trimerization. The invention further relates to a polyisocyanurate plastic having a functionalized surface obtainable from the process of the invention.

Claims

1.-16. (canceled)

17. A process for producing polyisocyanurate plastics having a functionalized surface, comprising the following steps: a) providing a polyisocyanate composition A) containing monomeric and/or oligomeric polyisocyanates; b) catalytically trimerizing the polyisocyanate composition A) so as to obtain a bulk polyisocyanurate material as intermediate; c) surface functionalizing the intermediate by contacting at least one surface of the intermediate with at least one functionalizing reagent D); d) continuing the catalytic trimerization.

18. The process according to claim 17, wherein the polyisocyanurate intermediate obtained in step b) has a viscosity sufficiently high that complete mixing does not take place in the course of contacting with the functionalizing reagent in step c), but at least an intact layer of the bulk polyisocyanurate material is instead conserved.

19. The process according to claim 17, wherein the catalytic trimerization in step b) is continued until a viscosity of at least 100 000 mPas or the gel point has been attained.

20. The process according to claim 17, wherein the catalytic trimerization in step b) is effected up to a conversion level at which more than 20% of isocyanate groups originally present in the polyisocyanate composition A) are present.

21. The process according to claim 17, wherein the continuation of the catalytic trimerization in step d) is effected up to a conversion level at which only at most 20% of isocyanate groups originally present in the polyisocyanate composition A) are present.

22. The process according to claim 17, wherein the contacting in step c) is effected by flow coating, dipping, spraying, printing, pipetting, roller coating, bar coating, scattering, vapour deposition and/or painting.

23. The process according to claim 17, wherein excess functionalizing reagent D) is removed between steps c) and d).

24. The process according to claim 17, wherein the functionalizing reagent D) is selected from the group consisting of compounds containing alcohol, thiol, amine, epoxide, anhydride, organic acid, isocyanate groups and mixtures thereof.

25. The process according to claim 17, wherein the polyisocyanate composition A) contains predominantly oligomeric polyisocyanates and is low in monomeric polyisocyanates, wherein said low in monomeric polyisocyanates wherein the polyisocyanate composition A) has a content of monomeric polyisocyanates of not more than 20% by weight, based on the weight of the polyisocyanate composition A).

26. Process according to claim 25, wherein the polyisocyanate composition A) has a content of monomeric polyisocyanates of not more than 15% by weight, based on the weight of the polyisocyanate composition A).

27. Process according to claim 25, wherein the polyisocyanate composition A) has a content of monomeric polyisocyanates of not more than 5% by weight, based on the weight of the polyisocyanate composition A).

28. The process according to claim 17, wherein the isocyanurate structure content in the polyisocyanate composition A) is at least 20 mol %, based on the sum total of the oligomeric structures from the group consisting of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione structure present in the polyisocyanate composition A).

29. The process according to claim 17, wherein the polyisocyanate composition A) consists to an extent of at least 80% by weight, based on the weight of the polyisocyanate composition A), of monomeric diisocyanates and/or oligomeric polyisocyanates having exclusively aliphatically and/or cycloaliphatically bonded isocyanate groups, where the oligomeric polyisocyanates optionally have exclusively aliphatically and/or cycloaliphatically bonded isocyanate groups.

30. The process according to claim 17, wherein the polyisocyanate composition A) consists to an extent of at least 95% by weight, based on the weight of the polyisocyanate composition A), of monomeric diisocyanates and/or oligomeric polyisocyanates having exclusively aliphatically and/or cycloaliphatically bonded isocyanate groups, where the oligomeric polyisocyanates optionally have exclusively aliphatically and/or cycloaliphatically bonded isocyanate groups.

31. The process according to claim 17, wherein the oligomeric polyisocyanates consist of one or more oligomeric polyisocyanates formed from 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, isophorone diisocyanate or 4,4-diisocyanatodicyclohexylmethane or mixtures thereof, and/or in that the monomeric polyisocyanates consist of one or more monomeric diisocyanates selected from 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, isophorone diisocyanate or 4,4-diisocyanatodicyclohexylmethane or mixtures thereof.

32. The process according to claim 17, wherein the polyisocyanate composition A) has a mean NCO functionality of 2.0 to 5.0 and/or the polyisocyanate composition A) has a content of reactive isocyanate groups of 8% to 60% by weight, based on the weight of the polyisocyanate composition A).

33. The process according to claim 17, wherein the oligomeric polyisocyanates are selected from at least one oligomeric polyisocyanate having uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione or oxadiazinetrione structure or mixtures thereof.

34. A polyisocyanurate plastic having a functionalized surface obtainable from the process according to claim 17.

Description

EXAMPLES

[0146] All percentages are based on weight, unless stated otherwise.

[0147] All the viscosity measurements were made with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) to DIN EN ISO 3219.

[0148] The glass transition temperature T was 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 in the table below 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 glass transition temperature T.sub.g determined was the temperature at half the height of a glass transition step.

[0149] Shore hardnesses were measured on the underside of the specimens to DIN 53505 with the aid of a Zwick 3100 Shore hardness tester (from Zwick, Germany) at 23 C. and 50% air humidity.

[0150] The contents (mol %) of the uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structures present in the starting polyisocyanates were 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.

[0151] IR spectra were recorded on a TraTwo FT-IR spectrometer equipped with an ATR unit from Perkin Elmer, Inc.

Starting Materials

Starting Polyisocyanate (Oligomeric Polyisocyanate)

[0152] HDI polyisocyanate containing isocyanurate groups, prepared in accordance with Example 11 of EP-A 330 966, with the alteration that the catalyst solvent used was 2-ethylhexanol rather than 2-ethylhexane-1,3-diol. The reaction was stopped at an NCO content of the crude mixture of 42% by adding dibutyl phosphate. Subsequently, unconverted HDI was removed by thin-film distillation at a temperature of 130 C. and a pressure of 0.2 mbar.

NCO content: 23.0%
NCO functionality: 3.2

Monomeric HDI: 0.1%

[0153] Viscosity (23 C.): 1200 mPas
Density (20 C.): 1.17 g/cm.sup.3

[0154] Distribution of the oligomeric structure types:

Isocyanurate: 89.7 mol %

Iminooxadiazinedione 2.5 mol %

Uretdione 2.7 mol %

Allophanate: 5.1 mol %

Functionalizing Reagents:

[0155] 1. glycerol (hydrophilic) [0156] 2. lauryl alcohol (hydrophobic) [0157] 3. Dytek A (hydrophilic) [0158] 4. Desmophen NH 1220 (hydrophilic) [0159] 5. Dabco 33LV (urethanization catalyst)

[0160] Glycerol and lauryl alcohol were purchased from Merck in PA quality, and each was blended with 3% of a solution of Dabco 33LV (33% strength) based on the total amount of polyol as urethanization catalyst and used as such.

[0161] Dytek A was purchased from Sigma-Aldrich in PA quality and used as such.

[0162] Desmophen NH 1220 (sterically hindered secondary diamine) was purchased from Bayer Material Science and used as obtained.

[0163] HDI=hexamethylene diisocyanate=Desmodur H was purchased from Bayer Material Science and used as obtained.

[0164] Dabco 33LV purchased from Sigma-Aldrich and used as obtained.

Working Example

Inventive Process

[0165] 100 g of the starting polyisocyanate were weighed into a polypropylene cup together with a catalyst mixture consisting of 0.177 g of potassium acetate, 0.475 g of [18]crown-6 and 3.115 g of diethylene glycol, and homogenized at 2750 rpm with the aid of a Speed-Mixer DAC 150 FVZ (from Hauschild, Germany) for 1 min. 16 g of the contents of the polypropylene cup in each case were weighed into an aluminium dish of diameter 6.3 cm and depth 1 cm. The aluminium dish thus filled was heated in a drying cabinet at 50 C. for 40 min. During this time, the starting polymer was converted by progressive trimerization of the starting polyisocyanate used to a gel-like mass which no longer forms threads at RT after contact with a wooden splint, achieving a conversion of <80% of the isocyanate groups used.

[0166] 2.5 g of the respective functionalizing reagent were poured onto the polyisocyanurate mass thus obtained. According to the functionalizing reagent chosen, the blanketed mass was kept at a selected temperature (see table of experiments in each case) for a selected time. Thereafter, it was cooled to RT and excess functionalizing reagent was removed by repeated washing with acetone and water, and the mass having surface functionalization on one side that was thus obtained was cured at 180 C. for 10 minutes up to a conversion of more than 80%, based on the isocyanate groups used in the starting polyisocyanate, by continuing the trimerization. Alternatively, the functionalizing reagent is poured onto the gel-like mass and heated together therewith to 180 C. for 10 minutes and then, as described above, excess functionalizing reagent is removed by repeated washing with acetone and water.

Non-Inventive Process

[0167] 100 g of the starting polyisocyanate were weighed into a polypropylene cup together with a catalyst mixture consisting of 0.177 g of potassium acetate, 0.475 g of [18]crown-6 and 3.115 g of diethylene glycol, and homogenized at 2750 rpm with the aid of a Speed-Mixer DAC 150 FVZ (from Hauschild, Germany) for 1 min. 16 g of the contents of the polypropylene cup in each case were weighed into an aluminium dish of diameter 6.3 cm and depth 1 cm. The aluminium dish thus filled was heated in a drying cabinet at 150 C. for 40 min, and the starting polyisocyanate present was preferentially converted by trimerization to a polyisocyanurate. In the course of this, the starting polymer was converted to a solid mass, achieving a conversion of >80%, based on the isocyanate groups used in the starting polyisocyanate.

[0168] The functionalizing was effected analogously to the inventive process by cooling to RT, blanketing with functionalizing reagent, etc.

[0169] The results of the functionalization are compared by means of surface IR analysis (ATR) with reference to succinct signals. For comparison, for the functionalized side and the unfunctionalized side, the NHOH vibration in the region of about 3400 cm.sup.1, the bands corresponding to the CH stretch vibration in the region of about 2900 cm.sup.1, and the bands corresponding to the NCO vibration in the region of about 2300 cm.sup.1 and to the isocyanurate vibration in the region of about 1650 cm.sup.1 were compared in terms of peak height. For this purpose, normalization was effected in each case to the isocyanurate vibration of the functionalized and unfunctionalized side. If the ratios of isocyanurate vibration to isocyanate vibration to CH stretch vibration and NHOH vibration differ, this is a clear indication of an altered chemical surface, i.e. that surface modification or functionalization has taken place. The examples cited are intended to illustrate merely the method in principle. Contact conditions, residual isocyanate content and reactivity of the reagents allow a broad variation in the desired surface modification or functionalization in terms of absolute magnitude and in terms of penetration depth, i.e. the depth to which the functionalizing reagent penetrates during the contact time proceeding from the surface of the bulk material into the interior of the bulk material.

TABLE-US-00001 Peak height ratios in ATR measurement: OHNH to CH stretch to NCO to isocyanurate Functionalizing unfunctionalized Sample reagent Conditions functionalized 1 glycerol 30 min 50 C. 0.1:0.5:0:2 0.4:0.6:0:2 2 10 min 180 C. 0.05:0.5:0:2 3:2:0:2 3 lauryl alcohol 30 ml/min; 50 C. 0.05:0.4:0.1:2.2 0.3:0.8:0:2.2 4 10 min 180 C. 0.05:0.4:0.1:2.2 0.2:0.8:0.1:2.2 5 Desmophen 10 ml/min; 23 C. 0.05:0.4:0.2:2.2 NH1220 0.2:0.4:0.7:2.2 6 20 min 50 C. 0.05:0.3:0.1:2 0.2:0.6:0.3:2.2 7 Dytek A 10/23 C. 0.05:0.35:0.1:2 0.4:0.9:0.05:2 8-14 Comparative Analogous execution of the Before and after functionalization experiments functionalization to 1-7 by the non-inventive process, no 8, 9 glycerol proceeding from a significant difference in the ATR 10, 11 lauryl alcohol specimen with >80% analyses of the surfaces was 12, 13 Desmophen conversion of isocyanate found. What was obtained was NH1220 functionality of the starting always the spectrum of a typical 14 Dytek A polyisocyanate unfunctionalized surface with the with following peak ratios: 1 as 8, 2 as 9, etc. 0.1:0.4:0.1:2

[0170] The inventive examples show consistently clear functionalization of the surface with a wide variety of different functionalizing reagents. Well-defined surfaces are obtained which clearly differ from unfunctionalized bodies. It can also be seen that functionalizing reaction does not significantly impair the final curing and further reaction of the starting polyisocyanate by trimerization by the process of the invention.