Method for producing a polyisocyanurate composite material

Abstract

The invention relates to a process for producing a composite polyisocyanurate material, comprising the following steps: a) providing a polyisocyanate composition A) which comprises oligomeric polyisocyanates and is low in monomeric diisocyanates, “low in monomeric diisocyanates” meaning that the polyisocyanate composition A) has a content of monomeric diisocyanates of not more than 20% by weight, and b) catalytically trimerizing the polyisocyanate composition A) in the presence of at least one fibrous filler B) and of a trimerization catalyst C) to give the composite polyisocyanurate material, where the trimerization catalyst C) comprises at least one metal salt and/or quaternary ammonium salt. The invention further relates to composite polyisocyanurate materials obtainable by the process according to the invention and to the use thereof for production of a component, and to components consisting of or comprising a composite polyisocyanurate material according to the invention.

Claims

1. A process for producing a composite polyisocyanurate material, comprising the following steps: a) providing a polyisocyanate composition A) consisting of one or more oligomeric polyisocyanates and not more than 0.5% by weight of one or more unconverted monomeric diisocyanates, based on the weight of the polyisocyanate composition A), and b) catalytically trimerizing the polyisocyanate composition A) in the presence of at least one fibrous filler B) and of a trimerization catalyst C) to give the composite polyisocyanurate material, wherein the trimerization catalyst C) comprises at least one of a metal salt and a quaternary ammonium salt and an optional polyether; and the trimerization catalyst C) is provided in an amount of from 0.4% to 15.0% by weight based on the weight of the polyisocyanate composition A); wherein each of the one or more oligomeric polyisocyanates is prepared by: reacting an excess of monomeric diisocyanate, yielding the oligomeric polyisocyanate and the unconverted monomeric diisocyanate, and removing at least a portion of the unconverted monomeric diisocyanate; and wherein at least 70 wt % of the one or more oligomeric polyisocyanates are oligomeric aliphatic polyisocyanates and/or oligomeric alicyclic polyisocyanates.

2. The process according to claim 1, wherein at least 80%, 85%, 90%, 95%, 98% or 99% by weight of the one or more oligomeric polyisocyanates are oligomeric aliphatic polyisocyanates and/or oligomeric alicyclic polyisocyanates.

3. The process according to claim 1, wherein the polyisocyanate composition A) has a mean NCO functionality of 1.0 to 6.0.

4. The process according to claim 1, wherein at least 50 mol %, based on the sum total of the oligomeric polyisocyanates in the polyisocyanate composition A), have a structure selected from the group consisting of uretdione, urethane, isocyanurate, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione.

5. The process according to claim 1, wherein 100 mol %, based on the sum of the oligomeric polyisocyanates in the polyisocyanate composition A), have a structure selected from the group consisting of uretdione, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione.

6. The process according to claim 1, wherein the fibrous filler B) is selected from the group consisting of glass fibres, basalt fibres, carbon fibres and mixtures thereof.

7. The process according to claim 1, wherein the fibrous filler B) is glass fibres.

8. The process according to claim 1, wherein the trimerization catalyst C) comprises an alkali metal salt or alkaline earth metal salt of a carboxylic acid.

9. The process according to claim 1, wherein the trimerization catalyst C) comprises potassium acetate.

10. The process according to claim 1, wherein the trimerization catalyst C) further comprises a polyethylene glycol as the polyether.

11. The process according to claim 1, wherein the catalytic trimerization is conducted at a temperature of greater than 150° C. within less than 10 minutes, at least up to a conversion level at which only at most 20% of isocyanate groups originally present in the polyisocyanate composition A) are still present.

12. The process according to claim 11, wherein the conversion level is a conversion level at which only at most 10% of the isocyanate groups originally present in the polyisocyanate composition A) are present.

13. A composite polyisocyanurate material obtained by a process according to claim 1.

14. The composite polyisocyanurate material according to claim 13, wherein the amount of nitrogen in the composite polyisocyanurate material is at least 9% by weight, based on the total weight of the polyisocyanurate plastic matrix in the composite polyisocyanurate material.

15. The composite polyisocyanurate material according to claim 13, wherein the proportion by weight of metal or metal ions in the composite polyisocyanurate material is at least 0.00025% by weight, based on the polyisocyanate composition A).

16. The composite polyisocyanurate material according to claim 13, wherein the composite polyisocyanurate material has a density of greater than 1.30 g/cm.sup.3 determined according to DIN EN ISO 1183-1.

17. Components consisting of or comprising a composite polyisocyanurate material according to claim 13.

Description

GENERAL DETAILS

(1) All percentages, unless stated otherwise, are based on percent by weight (% by weight).

(2) The ambient temperature of 25° C. at the time of conduct of the experiments is referred to as RT (room temperature).

(3) The NCO functionality of the various raw materials was in each case determined by calculation or taken from the respective datasheet for the raw material.

Test Methods

(4) The methods detailed hereinafter for determining the relevant parameters were employed for performing/evaluating the examples and are also the methods for determining the parameters relevant in accordance with the invention in general.

Determination of Yellowing by Means of Cie-Lab Measurement

(5) After crosslinking and cooling, the composite material was removed from the mould and the measurement was conducted on the lower, smooth face of the material. For this purpose, a color-guide sphere spin colorimeter from BYK-Gardner GmbH with CIE L*a*b system scale, d/8° measurement geometry and D65/10° illuminant/observer was used. The value used corresponds to the arithmetic mean of 5 measurements.

Determination of Tg by Means of DSC

(6) The glass transition temperature T.sub.g 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 stated below are based in each case on the evaluation of the 1st heating curve since in the investigated reactive systems, changes in the sample are possible in the measuring process at high temperatures 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.

Determination of Shore Hardnesses

(7) Shore hardnesses were measured to DIN 53505 with the aid of a Zwick 3100 Shore hardness tester (from Zwick, Germany) at 23° C. and 50% air humidity.

Determination of Weathering Resistance

(8) The weathering tests were conducted in a Ci5000 from Atlas Material Testing Technology. The samples were placed into the instrument with the smooth side facing the xenon lamp and the cycles were run in accordance with the standard SAE J 2527. At particular intervals, visual examinations were conducted for cracks, surface gloss and smoothness, appearance and change in colour. For comparison, a second sample was produced as well in each case, but was not weathered and instead kept in the dark at room temperature and 40% to 70% relative humidity and utilized as reference.

Determination of Pot Life

(9) The viscosity of a small amount of the reactive resin material including the added catalyst was measured at 23° C. with a Physica MCR 51 from Anton Paar (plate/plate; shear rate 1 s.sup.−1). The pot life was the time taken for the viscosity of the sample to double.

Experimental Determination of the Nitrogen Content of the Polymer Matrix in the Finished Composite Polyisocyanurate Material

(10) A few milligrams of the polymer matrix were cautiously scraped away from the composite polyisocyanurate material. A portion of this is burnt under an air atmosphere in TGA (1000° C.), and the noncombustible solids content (fibre, inorganic fillers) is determined as the residue. Then the nitrogen content is determined with a further portion of the sample in a vario EL Cube from elementar Americas INC. The difference is determined to calculate the nitrogen content in the matrix.

Theoretical Determination of the Nitrogen Content of the Polymer Matrix in the Finished Composite Polyisocyanurate Material

(11) The nitrogen content is ascertained as the sum total of all nitrogen atoms present in the polymer matrix from organic materials, i.e. from isocyanate groups, organic additives with amino groups, aromatic heterocycles with nitrogen functionalities etc., divided by the total amount of organic compounds and multiplied by 100%.

Feedstocks

(12) Desmodur N 3600 is an HDI trimer (NCO functionality >3) with an NCO content of 23.0% by weight from Covestro AG. The viscosity is about 1200 mPas at 23° C. (DIN EN ISO 3219/A.3).

(13) Desmodur H is an HDI monomer (NCO functionality 2) with an NCO content of 49.7% by weight from Covestro AG. The viscosity is about 3 mPas at 23° C. (DIN EN ISO 3219/A.3).

(14) Desmodur ECO N 7300 is a PDI timer (NCO functionality >3) with an NCO content of 21.5% by weight from Covestro AG. The viscosity is about 9500 mPas at 23° C. (DIN EN ISO 32191A.3).

(15) Desmodur I is an IPDI monomer (NCO functionality 2) with an NCO content of 37.5% by weight from Covestro AG. The viscosity is about 10 mPas at 23° C. (DIN EN ISO 3219/A.3).

(16) Desmodur W is an H12MDI monomer (NCO functionality 2) with an NCO content of 31.8% by weight from Covestro AG. The viscosity is about 30 mPas at 23° C. (DIN EN ISO 3219/A.3).

(17) Polyethylene glycol 400 was sourced with a purity of >99% by weight from ACROS.

(18) Triethylene glycol was sourced with a purity of >99% by weight from ACROS.

(19) Potassium acetate was sourced with a purity of >99% by weight from ACROS.

(20) The short glass fibres designated 910A-10P were supplied by Owens Corning and were in the form of bundles of about 4.5 mm in length. The diameter of the individual fibres was 0.01 mm.

(21) All raw materials except for the catalyst were degassed under reduced pressure prior to use, and the polyols were additionally dried.

Preparation of the Catalyst

(22) Potassium acetate (5.0 g) was stirred in the 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 was obtained and was used as catalyst without further treatment.

Production of the Polyisocyanurate Composites

(23) Unless stated otherwise, the polyisocyanurate composites were produced by first preparing the isocyanate composition by mixing the appropriate isocyanate components at 25° C. in a Speedmixer DAC 150.1 FVZ from Hauschild at 2750 min.sup.−1 for 60-300 seconds. This was then mixed with the catalyst at RT (Speedmixer). Subsequently, one tenth of the amount of glass fibres was added at first. The overall mixture was mixed in a Speedmixer DAC 150.1 FVZ from Hauschild at 2750 min.sup.−1 for 60 to 300 seconds, in the course of which the short glass fibre bundles are exfoliated and the whole mixture forms a slurry-like mass. Then the remaining amount of glass fibres is added and the mixture is mixed again in the Speedmixer at 2750 min.sup.−1 for about 60 seconds.

(24) Subsequently, the mixture was transferred to a mould (metal lid, about 6 cm in diameter and about 1 cm in height) and cured in an oven. This was done using the following heating programme: 30 min at 180° C. in the presence of Desmodur I or W; otherwise 30 min at 160° C.

Inventive Examples for the Production of the Composite Polyisocyanurate Materials

Inventive Example

(25) As described above, Desmodur N 3600 (40.0 g) was mixed with catalyst (0.80 g), the short glass fibres (20.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 6.71. The pot life was more than 5 hours. In the weathering test, after 1000 hours, no changes in the surface or colour were noted on visual inspection.

Inventive Example 2

(26) As described above, a mixture of Desmodur N 3600 (36.0 g) and Desmodur H (4.0 g) was mixed with catalyst (0.80 g), the short glass fibres (30.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 6.39.

Inventive Example 3

(27) As described above, a mixture of Desmodur N 3600 (36.0 g) and Desmodur H (4.0 g) was mixed with catalyst (0.80 g), the short glass fibres (20.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 6.77. The pot life was more than 5 hours. In the weathering test, after 1000 hours, no changes in the surface or colour were noted on visual inspection. The Tg was 117° C.

Inventive Example 4

(28) As described above, Desmodur N 3600 (40.0 g) was mixed with catalyst (0.80 g), the short glass fibres (30.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 6.40. The pot life was more than 5 hours.

Inventive Example 5

(29) As described above, a mixture of Desmodur N 3600 (30.0 g) and Desmodur ECO N 7300 (10.0 g) was mixed with catalyst (0.80 g), the short glass fibres (20.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 7.89. The pot life was more than 5 hours. In the weathering test, after 1000 hours, no changes in the surface or colour were noted on visual inspection.

Inventive Example 6

(30) As described above, a mixture of Desmodur N 3600 (20.0 g) and Desmodur ECO N 7300 (20.0 g) was mixed with catalyst (0.80 g), the short glass fibres (20.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 7.60. The pot life was more than 5 hours. The Tg was 124° C.

Inventive Example 7

(31) As described above, a mixture of Desmodur H (5.0 g) and Desmodur ECO N 7300 (45.0 g) was mixed with catalyst (1.00 g), the short glass fibres (25.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 7.4. The pot life was more than 180 minutes. In the weathering test, after 9000 hours, no changes in the surface or colour were noted on visual inspection.

Inventive Example 8

(32) As described above, a mixture of Desmodur N 3600 (32.0 g) and Desmodur W (8.0 g) was mixed with catalyst (0.80 g), the short glass fibres (40.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was less than 7.

Inventive Example 9

(33) As described above, a mixture of Desmodur N 3600 (32.0 g) and Desmodur I (8.0 g) was mixed with catalyst (0.80 g), the short glass fibres (40.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was less than 7.

Non-Inventive Examples for the Production of the Composite Polyisocyanurate Materials

Comparative Example

(34) As described above, a mixture of Desmodur N 3600 (36.0 g) and Desmodur H (4.0 g) was mixed with catalyst (0.012 g), the short glass fibres (20.0 g) were incorporated and the mixture was pushed into the mould. The mixture was placed in the oven at 160° C. for 30 minutes. After this time, the mixture was still tacky and not hard, i.e. the crosslinking reaction was incomplete. The material was not subjected to further analysis.

(35) Comparative Example 1 shows that the catalyst concentration below or equal to an amount of 0.03% by weight is insufficient to obtain a fully crosslinked polyisocyanurate plastic within a short time.

Comparative Example 2

(36) As described above, a mixture of Desmodur N 3600 (30.0 g) and Desmodur H (10.0 g) was mixed with catalyst (0.80 g), the short glass fibres (20.0 g) were incorporated and the mixture was pushed into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b value measured was 8.27. The pot life was more than 5 hours.

(37) Comparative Example 2 shows that, in the case of a monomer content exceeding 20% by weight, there is a distinct rise in the b value measured, meaning that the visual appearance of the component deteriorates and there is onset of unwanted side reactions.

Non-Inventive Examples for Polyisocyanurate Materials Without Fibrous Filler

(38) Unless stated otherwise, the fibre-free polyisocyanurate materials were produced by first preparing the polyisocyanate composition by mixing the appropriate isocyanate components at 25° C. in a Speedmixer DAC 150.1 FVZ from Hauschild at 2750 min.sup.−1 for 60-300 seconds. This was mixed with the catalyst at room temperature (RT) (Speedmixer). Subsequently, the mixture was transferred to a mould (metal lid, about 6 cm in diameter and about 1 cm in height) and cured in an oven. This was done using the following heating programme: 30 min at 180° C. in the presence of Desmodur I or W; otherwise 30 min at 160° C.

Comparative Example 3

(39) As described above, a mixture of Desmodur N 3600 (36.0 g) and Desmodur H (4.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b* value measured was 9.16.

Comparative Example 4

(40) As described above, a mixture of Desmodur N 3600 (30.0 g) and Desmodur H (10.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b* value measured was 9.44.

Comparative Example 5

(41) As described above, a mixture of Desmodur N 3600 (30.0 g) and Desmodur ECO N 7300 (10.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b* value measured was 9.80. The pot life was more than 180 minutes.

Comparative Example 6

(42) As described above, a mixture of Desmodur N 3600 (20.0 g) and Desmodur ECO N 7300 (20.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b* value measured was 11.72. The pot life was more than 180 minutes.

Comparative Example 7

(43) As described above, Desmodur H (20.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. When heated, the reaction proceeded in a violent and highly exothermic manner with formation of smoke. The product obtained was a blistered, brown to dark brown porous material that was not subjected to further analysis.

Comparative Example 8

(44) As described above, a mixture of Desmodur N 3600 (30.0 g) and Desmodur W (10.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b* value measured was 13.3.

Comparative Example 9

(45) As described above, a mixture of Desmodur N 3600 (30.0 g) and Desmodur I (10.0 g) was mixed with catalyst (0.80 g) and the mixture was poured into the mould. After curing, the block was removed from the mould and the smooth reverse side was analysed with the colorimeter. The b* value measured was 19.

(46) The experiments show that the composite polyisocyanurate materials according to the invention from Inventive Examples 1 to 7 have distinctly lower yellowing (a lower yellow value or b value) compared to the fibre-free polyisocyanurate materials. This means that the fully reacted polyisocyanurate matrix material of the composite polyisocyanurate materials according to the invention, under the severe reaction conditions is subject to much less damage compared to the fibre-free polyisocyanurate material or no damage. Moreover, the reactive resin mixtures with the catalyst concentrations used here exhibited pot lives of more than 30 min with simultaneously rapid crosslinking times, which very closely approximates to a one-component system and enables very easy practical handling. It is therefore possible to dispense with inconvenient and costly metering apparatus as necessary in the case of two-component systems. This should pave the way for the efficient utilization of pure, fibre-reinforced composite polyisocyanurate materials in industry.