Process for the preparation of multifunctional polycarbodiimides which are used as crosslinking agents

Abstract

A process for the preparation of multifunctional polycarbodiimides, which are used as crosslinking agents, in which the polycarbodiimide is prepared by reacting mono- and polyisocyanates in the presence of a mono- or polyisocyanate that contains one or multiple additional reactive functional groups and in the presence of a carbodiimide catalyst, and thereafter terminating or chain extending the polycarbodiimide chain. Between 0 and 10% of an organic solvent and/or between 0 and 30% of a plasticizer and/or between 0 and 30% of a surface active component is added to the product during, before or after the polycarbodiimide forming reaction and/or the capping reaction and/or the chain extending reaction. Further, the invention relates to a coating mixture in which the polycarbodiimide is used as crosslinking agent and to the cured material obtained with the coating mixture.

Claims

1. A process for the preparation of water-dispersible multifunctional polycarbodiimides to be used as crosslinking agents, comprising: A. the reaction of a mono- and/or polyisocyanate at 80-180 C. in the presence of a carbodiimide catalyst, in which a polycarbodiimide or an isocyanate functional polycarbodiimide is formed with a mean value of 1-10 carbodiimide functions; B. terminating and/or chain extending the isocyanate functional polycarbodiimide chain, during or after the formation of the polycarbodiimide chain by the addition of 0.05 to 1.0 equivalent, regarding to the isocyanate functions that are not consumed in the formation of the polycarbodiimide chain, of a compound containing a hydrophilic group and one or multiple amine and/or hydroxyl functions, together with, prior to, or followed by capping of the remaining isocyanate functions with a compound containing one or multiple amine and/or hydroxyl functions, in which the compound containing one or multiple amine and/or hydroxyl functions can also contain an additional functional group, where in step A one or multiple mono- and/or polyisocyanates containing one or multiple additional functional groups, of which the isocyanate group contributes to the carbodiimide formation is present, at least one of said additional functional groups being selected from the group consisting of: halogen; alkenyl; arylalkene; alkynyl; arylalkyn; alkadiene; aldehyde; dialkylacetal; dithioacetal; ketone; unsaturated aldehyde; ketone; ketone ester; carboxylic ester; nitrile; imine; alkylalkoxy silane; alkoxysilane; anhydride; mixed anhydride; oxime-protected diisocyanate; diketone; ketoester; thioketoester; ketothioester; and thioketothioester.

2. A process according to claim 1, wherein said mono- and/or polyisocyanate that contains an additional functional group contains a trimethoxysilane, dimethoxymethylsilane or a tri-ethoxysilane as additional reactive functional group.

3. A process according to claim 1, wherein said mono- and/or polyisocyanate that contains an additional functional group contains as additional reactive functional group a three, four, five, six, seven or eight membered ring that contains one or multiple nitrogen and/or oxygen and/or sulphur and/or keto and/or keto-enol functions.

4. A process according to claim 1, wherein said mono- and/or polyisocyanate that contains an additional functional group is (3-isocyanato-propyl)trimethoxysilane, (3-isocyanatopropyl)tri-ethoxysilane or (3-isocyanatopropyl)methyldimethoxysilane.

5. A process according to claim 1, wherein the polycarbodiimide crosslinker contains no solvent.

6. A process according to claim 1, wherein the polycarbodiimide crosslinker contains no plasticizer.

7. A process according to claim 1, wherein the plasticizer is a phosphate ester, polyetherpolyester or a polyether.

8. A process according to claim 1, wherein the compound containing one or multiple amine and/or hydroxyl functions that can also contain an additional functional group contains an additional functional group that is an additional reactive functional group selected from the group consisting of: a halogen; alkenyl; arylalkene; alkynyl; arylalkyn; alkadiene; aldehyde; dialkylacetal; dithioacetal; ketone; unsaturated aldehyde; ketone ester; carboxylic ester; nitrile; imine, alkyloxy silane; alkoxysilane; anhydride; mixed anhydride; oxime-protected diisocyanate; diketone; ketoester; thioketoester; ketothioester; and thioketo-thioester.

9. A process according to claim 8, wherein the additional reactive functional group in the compound that contains one or multiple amine and/or hydroxyl functions together with one or multiple additional reactive functional groups is a trimethoxysilane, a triethoxysilane, an epoxide; an aziridine or an oxazolidine group.

10. A process according to claim 1, wherein the polyisocyanate is dicyclohexylmethane-4, 4-diisocyanate or 3-isocyanatomethyl-3,5,5-trimethyl-cyclohexylisocyanate.

11. A process according to claim 1, wherein the compound containing an hydrophilic group and one or more amine and/or hydroxyl functions is a polyethoxy mono- or diol with a molecular weight between 100 and 3000 Dalton, a polyethoxy mono- or diamine with a molecular weight between 100 and 3000, a diol or diamine containing a pendant polyalkoxy chain, an hydroxyl- or amine alkylsulfonate, or a dialkylamino-alkyl-alcohol or amine, or a mixture thereof, wherein all molecular weights are number average molecular weights.

12. A process according to claim 1, wherein 0.05 to 0.30 equivalents, regarding to the polyisocyanates, of a mono- or polyol or a mono- or polyamine are added during, before or after the formation of the polycarbodiimide chain, which mono- or polyol or mono- or polyamine is a mono- or polyhydroxy alkane, a polyether mono- or polyol, a polyester polyol, a polycarbonate polyol, a polycaprolactam polyol, a mono- or polyamino alkane, or a polyether mono- or polyamine.

13. A process according to claim 1, wherein an organic solvent and/or a plasticizer and/or a surface active component is added, during, before or after the carbodiimide forming reaction and/or the capping reaction and/or the chain extending reaction.

14. A process according to claim 1, wherein no surface active component is added, during, before or after the carbodiimide forming reaction and/or the capping reaction and/or the chain extending reaction.

Description

EXAMPLES

Examples 1-26

The Preparation of Multifunctional Polycarbodiimides

(1) Under a nitrogen atmosphere a mixture of diisocy-anate, octadecylisocyanate (in the following indicated as ODIC), and an isocyanate with an additional functional group as indicated in Table 1 and 1-methylphospholene-1-oxide was heated to 140 C. while stirring and heating was continued until a NCO-content was obtained corresponding to the desired theoretical amount of carbodiimide functions in the polymer, as indicated in Table 1. The reaction time was 4 to 8 hrs. Then the mixture was cooled to 90-100 C. Hydroxyl functional compounds were added as indicated in Table 1. 0.01 Weight % of dibutyl tin laureate or bismuth carboxylate was added as catalyst and the mixtures were reacted further at 90-100 C. until the NCO-content was decreased such that this NCO-content corresponds with reacting away of the hydroxyl functional compounds. Amine functional compounds were added subsequently or simultaneously as indicated in Table 1. The completeness of the reaction was checked by infrared analysis. Plasticizers were added during or after the process steps described above, as indicated in Table 1. Samples were subjected to a stability test at 50 C. Every 2 weeks the carbodiimide amount was checked. The products were stable for at least 8 weeks at 50 C.

(2) TABLE-US-00001 TABLE 1 Theoretical Viscosity amount of of Diiso- X- MPEG- MPEG- Silane- carbodiimide product Ex- Diiso- cyanate ODIC NCO.sup.c) 750.sup.d) 350.sup.e) HDA.sup.f) OA.sup.g) NH.sup.h) Plasticizer functions at 20 C. ample cyanate (g) (g) (g) (g) (g) (g) (g) (g) (g) in polymer (mPa .Math. s) 1 IPDI.sup.a) 200 212 111.sup.k) 64 2.0 600 2 IPDI 200 89 125.sup.k) 105 2.0 1250 3 HMDI.sup.b) 200 75 105.sup.k) 91 2.0 1900 4 IPDI 200 115.sup.k) 113 61 2.0 6500 5 IPDI 200 77.sup.k) 105 3.0 38200 6 IPDI 200 77.sup.k) 87 23 TBEP.sup.i) 3.0 14400 7 IPDI 200 57.sup.k) 87 4.0 680000 8 IPDI 200 57.sup.k) 87 86 TBEP.sup.i) 4.0 156000 9 IPDI 200 38 26 90 3.5 43000 10 IPDI 200 115.sup.k) 113 86 TBEP.sup.i) 2.0 1500 11 HMDI 200 79.sup.k) 79 2.0 15000 12 IPDI 200 92.sup.k) 61 12 77 2.0 19000 13 IPDI 200 92.sup.k) 61 12 77 101 TG.sup.j) 2.0 750 14 IPDI 200 92.sup.k) 38 77 2.0 42000 15 IPDI 200 92.sup.k) 38 77 104 TG.sup.j) 2.0 1000 16 IPDI 200 92.sup.k) 55 29 31 2.0 18000 17 IPDI 200 92.sup.k) 55 29 31 92 TG 2.0 800 18 IPDI 200 92.sup.k) 51 64 40 2.0 22000 19 IPDI 200 92.sup.k) 51 64 40 102 TG 2.0 900 20 IPDI 200 103.sup.k) 52 24 71 1.8 37000 21 IPDI 200 103.sup.k) 52 24 71 130 TG 1.8 600 22 IPDI 200 103.sup.k) 52 39 79 1.8 20000 23 IPDI 200 103.sup.k) 52 39 79 136 TG 1.8 500 24 IPDI 200 103.sup.k) 52 39 79 136 TBEP 1.8 1300 25 IPDI 200 123.sup.l) 52 39 79 1.8 24000 26 IPDI 200 55.sup.m) 52 39 79 1.8 32000 27 IPDI 200 0 52 153 2.0 2400000 .sup.a)IPDI is 3-isocyanatomethyl-3,5,5-trimethlylcyclohexylisocyanate; .sup.b)HMDI is dicyclohexylmethaan-4,4-diisocyanate; .sup.c)X-NCO is an isocyanaat with an additional functional group, specified further in foot notes; .sup.d)MPEG750 is a polyehtylene glycol monomethyl either that has a mean molecular weight of 750; .sup.e)MPEG350 is a polyethlene glycol monomethyl ether that has a mean molecular weight of 350; .sup.f)HDA is hexadecylalcohol; .sup.g)OA is 1-octanol; .sup.h)Silane-NH is di-(3-trimethoxy-silylpropyl amine; .sup.i)TBEP is tributoxy-ethylphosphate; .sup.j)TG is tetraethylene glycol dimethylether; .sup.k)The isocyanate with additional functional group is (3-isocyanatopropyl)trimethoxysilane; .sup.l)The isocyanate with additional functional group is (3-isocyanatopropyl-ethoxysilane; .sup.m)The isocyanate with additional functional group is methacryloyl isocyanate

Example 27

Comparative Example

The Preparation of a Multifunctional Polycarbodiimide not Using an Isocyanate that Contains an Additional Functional Group

(3) Under a nitrogen atmosphere a mixture of diisocy-anate, as indicated in Table 1, and 1-methylphospholene-1-oxide was heated to 140 C. while stirring and heating was continued until a NCO-content was obtained corresponding to the desired theoretical amount of carbodiimide functions in the polymer, as indicated in Table 1. The reaction time was 4 to 8 hours. Then the mixture was cooled to 90-100 C. A hydroxyl functional compound was added as indicated in Table 1. 0.01 Weight % of dibutyl tin laureate was added as catalyst and the mixtures were reacted further at 90-100 C. until the NCO-content was decreased such that this NCO-content corresponds with reacting away the hydroxyl functional compounds.

(4) Subsequently an amine functional compound was added as indicated in Table 1. The completeness of the reaction was checked by infrared analysis.

(5) Comparing the viscosity of Example 27 with the viscosities of Examples 1 to 4 and 10 to 26 demonstrates that the viscosities of Examples 1 to 4 and 10 to 26 are much lower than the viscosity of Example 27 while the theoretical amount of carbodiimide functions in the polymer is the same. Also the viscosities of Examples 5 and 7 are much lower than the viscosity of Example 27 while the theoretical amount of carbodiimide functions in the polymer is higher in Examples 5 and 7 than in Example 27.

Example 28

(6) Testing of the products from Examples 2, 12, 13, 15, 19, 23 and 24 as crosslinker in a polyurethane dispersion with the product from Example 27 as comparative example. 6 weight % of the products from Examples 2, 12, 13, 15, 19, 23 and 24 were mixed with RU-13-085 (a polyurethane dispersion of +Stahl Europe) or with a top coat formulation (a mixture comprising several polyurethane dispersions of Stahl Europe). In case of comparative Example 27 first a 1:1 dilution in a solvent was made so that the processibility is improved and subsequently 12 weight % of this dilution was mixed with RU-13-085 or a top coat formulation. Each dispersion was, with a thickness of 200 i, applied on a glass sheet and the glass sheet with the applied film on it was dried for 1 day at room temperature and subsequently for 1 hour at 80 C. in an oven. Samples of the dried film were subjected to a solvent uptake test with ethanol or MEK (methyl-ethylketone, or 2-butanone) as solvent. In this test pieces of dried and weighted film are immersed into ethanol or MEK for 1 hour and then the increase of the weight of the film is determined.

(7) The weight increase in this solvent uptake test is a measure for the crosslinking in which a lower increase of weight indicates a higher degree of crosslinking. Further, the mechanical properties and the elongations of the films were measured with a MTS Synergy 200 apparatus. The mechanical properties are a measure for the crosslinking in which a larger stress value at a certain strain indicates a higher degree of crosslinking. The results of the tests are presented in Table 2.

(8) The results show that the crosslinking with the crosslinking agent of Examples 2, 12, 13, 15, 19, 23 and 24 is of a comparable degree as with comparative Example 27, which is demonstrated by the comparable strain in the film which is obtained when the film is stretched and by the comparable weight increase when the films are immersed in ethanol or MEK.

(9) TABLE-US-00002 TABLE 2 cross- Mechanical properties (MPa).sup.a) Weight Weight Poly- linker Elong- In- In- urethane used of ation.sup.b) crease crease dispersion Example M-100 M-200 % Ethanol.sup.c) MEK.sup.d) RU-13-085 None 5.5 8.6 570 88 Lost op RU-13-085 2 8.5 15.9 290 27 80 RU-13-085 12 11.6 23.7 215 27 72 RU-13-085 13 9.5 20.2 245 24 63 RU-13-085 23 9.8 20.5 250 25 55 RU-13-085 24 8.1 19 285 25 55 RU-13-085 27 12.1 25.2 220 27 56 Top coat None 2.8 3.9 225 53 63 Top coat 15 3.0 190 2 3 Top coat 19 2.8 165 10 4 Top coat 27 3.6 170 6 6 .sup.a)MPa is megapascal (10.sup.6 Nm.sup.2). The mechanical properties were measured on a MTS Synergy 200 apparatus. The values at M-100 and M-200 are strains of the films when they are stretched at respectively 100% and 200%. .sup.b)The elongation is the maximum elongation at the moment that the film breaks, measured on a MTS Synergy 200 apparatus. .sup.c)Weight increase is the % weight increase of the film as result of immersing into ethanol. .sup.d)Weight increase is the % weight increase of the film as result of immersing into MEK (methylethylketone, or 2-Butanone).