XDI-terminated polyurethane, and composition comprising said polyurethane

Abstract

The present invention relates to a novel XDI-terminated polyurethane. The present invention also relates to the use of said polyurethane for manufacturing an adhesive, mastic and/or surface coating composition, especially for the construction field, which is stable over time in terms of viscosity.

Claims

1. An XDI-terminated polyurethane based on methylene diphenyl diisocyanate or based on a mixture of meta-xylylene diisocyanate and methylene diphenyl diisocyanate, said polyurethane not being solid at a temperature ranging from 5 C. to 35 C., characterized in that the polyurethane is obtained using an XDI/(XDI+MDI) molar ratio ranging from 16% to 25% or strictly greater than 50%.

2. The polyurethane as claimed in claim 1, capable of being obtained by a polyaddition reaction of at least one polyol composition with at least one polyisocyanate composition, under anhydrous conditions, in amounts of polyisocyanate(s) and of polyol(s) leading to an NCO/OH molar ratio ranging from 1.6 to 2.5.

3. The polyurethane as claimed in claim 2, characterized in that the polyol composition is a mixture of polyether diol and of polyether triol.

4. The polyurethane as claimed in claim 1, characterized in that it is based on methylene diphenyl diisocyanate and is meta-xylylene diisocyanate-terminated.

5. The polyurethane as claimed in claim 4, capable of being obtained: by a first polyaddition reaction of at least one polyol composition with at least one methylene diphenyl diisocyanate composition, under anhydrous conditions, in amounts of polyisocyanate(s) and of polyol(s) leading to an NCO/OH molar ratio strictly less than 1 in order to obtain an OH-terminated polyurethane, followed by a second polyaddition reaction of the OH-terminated polyurethane with a meta-xylylene diisocyanate composition, under anhydrous conditions, in amounts of polyisocyanate(s) and of polyol(s) leading to an NCO/OH molar ratio ranging from 1.6 to 2.5.

6. The polyurethane as claimed in claim 1, obtained using an XDI/(XDI+MDI) molar ratio ranging from 16% to 25% or 55% to 95%, preferably ranging from 16% to 25%.

7. A polyurethane composition comprising at least one polyurethane as claimed in claim 1 and at least some residual meta-xylylene diisocyanate monomers.

8. A process for preparing a polyurethane as claimed in claim 1, said process comprising the mixing of a polyisocyanate composition comprising meta-xylylene diisocyanate and methylene diphenyl diisocyanate with a polyol composition.

9. The process as claimed in claim 8, wherein the mixing is carried out in two steps, the first step comprising a polyaddition reaction of at least one polyol composition with at least one methylene diphenyl diisocyanate composition, under anhydrous conditions, in amounts of polyisocyanate(s) and of polyol(s) leading to an NCO/OH molar ratio strictly less than 1 in order to obtain an OH-terminated polyurethane and the second step comprising a polyaddition reaction of said OH-terminated polyurethane with a meta-xylylene diisocyanate composition, under anhydrous conditions, in amounts of polyisocyanate(s) and of polyol(s) leading to an NCO/OH molar ratio ranging from 1.6 to 2.5.

10. A composition comprising: at least one polyurethane as claimed in claim 1, at least one filler, and at least one crosslinking catalyst.

11. The composition as claimed in claim 10, comprising: from 10% to 30% by weight of at least one polyurethane as claimed in claim 1, from 25% to 70% by weight of at least one filler, from 0.01% to 1% by weight of at least one crosslinking catalyst, the percentages by weight being expressed relative to the total weight of said composition.

12. The composition as claimed in claim 10, comprising less than 0.1% by weight of residual methylene diphenyl diisocyanate monomers and less than 0.5% by weight of residual meta-xylylene diisocyanate monomers, the percentages by weight being expressed relative to the total weight of said composition.

13. The composition as claimed in claim 10, which is in anhydrous form.

14. An article comprising the composition as claimed in claim 10 in airtight hermetic packaging.

15. The article as claimed in claim 14, wherein the hermetic packaging is an aluminum bag or an aluminum cartridge.

Description

EXAMPLES

Preparation of the Polyurethanes

(1) The polyurethanes of examples 1 to 5 according to the invention and of comparative examples A to D and of example 6 outside of the invention were prepared by mixing the ingredients indicated in tables 1 and 1a at a temperature below or equal to 95 C. under anhydrous conditions. The amounts indicated in tables 1 and 1a are expressed as a percentage by weight relative to the total weight of the polyurethane composition of each of the examples.

(2) When the polyurethane comprises both MDI units and XDI units, the process is sequential, that is to say that the MDI and the polyols were introduced in a first step in order to form an OH-terminated polyurethane, then in a second step the XDI was introduced in order to form the NCO-terminated polyurethane (terminated by an XDI unit).

(3) TABLE-US-00001 TABLE 1 comparative polyurethanes A B C D PPG triol having a number- 42 42.2 42.3 41 average molar mass of 4000 g/mol PPG diol having a number- 27.5 27.7 27.7 27 average molar mass of 2000 g/mol 4.4-MDI (% NCO = 14 11.9 10.68 11 33.6% by weight) XDI (% NCO = 44.7% 0 1.57 2.56 4.5 by weight) Catalyst (DOTL) 0.0006 0.006 0.006 0.006 Xylene 16.5 16.6 16.6 16.6 NCO/OH molar ratio 1.9 1.9 1.9 2.0 % by weight of final NCO 2.1 2.1 2.2 3.0 XDI/(XDI + MDI) molar 0 15.9 25.6 37.0 ratio in % Viscosity 25000 gel gel gel

(4) TABLE-US-00002 TABLE 1a polyurethanes 1 to 5 according to the invention and polyurethane 6 outside of the invention 1 2 3 4 5 6 PPG triol having a number- 41.8 41.7 41.4 41.9 42.5 42.5 average molar mass of 4000 g/mol PPG diol having a number- 27.4 27.4 27.2 27.5 27.9 27.9 average molar mass of 2000 g/mol 4.4-MDI (% NCO = 12.66 12.2 12.55 7.6 4.29 0 33.6% by weight) XDI (% NCO = 44.7% 1.70 2.1 2.51 6.35 8.6 12.87 by weight) Catalyst (DOTL) 0.0006 0.0006 0.006 0.006 0.0006 0.0006 Xylene 16.6 16.6 16.6 16.6 16.7 16.7 NCO/OH molar ratio 1.9 2.0 2.0 2.1 2.0 2.1 % by weight of final NCO 2.4 2.5 2.6 2.7 2.66 2.98 XDI/(XDI + MDI) molar 16.1 19.8 22.3 54.6 74.2 100 ratio in % Viscosity (D + 5) 56000 48000 50000 4960 40000 1600

(5) In table 1 above: The % by weight of final NCO corresponds to the amount of NCO functions in the polyurethane at the end of the polyurethane preparation reaction, expressed relative to the total weight of polyurethane. The viscosity of the polyurethane composition is measured 5 days after the end of the reaction (D+5) at 23 C. under anhydrous storage conditions. The viscosity measurement is carried out at 23 C. using a Brookfield RVT viscometer, with a number 6 spindle at a speed of rotation of 20 revolutions per minute (rpm). The value measured is expressed in millipascal-seconds (mPa.Math.s).

(6) The polyurethanes A and 1 to 6 were characterized before being formulated in mastic compositions: The viscosity of the polyurethane composition is measured 1 day after the end of the reaction V(D+1) then 7 days after the end of the reaction V(D+7) at 23 C. under anhydrous storage conditions. The viscosity measurement is carried out at 23 C. using a Brookfield RVT viscometer, with a number 6 spindle at a speed of rotation of 20 revolutions per minute (rpm). The value measured is expressed in millipascal-seconds (mPa.Math.s). The modulus at 100% is measured according to the standard ISO 11600 (referring especially to the standard ISO 8339). The elongation at break is measured according to the standard NF ISO 37 (March 2012), The modulus of rupture is measured according to the standard ISO 11600 (referring especially to the standard ISO 8339).

(7) The results of the characterization are indicated in table 2 below.

(8) TABLE-US-00003 TABLE 2 characterization of the polyurethanes A 1 2 3 4 5 6 V(D + 1) 8000 51000 3500 37000 1400 V(D + 7) 20000 30000 48000 59000 4960 40000 1600 Modulus 1020 1110 1150 1250 1190 2170 2470 at 100% (MPa) Elongation 310 290 310 354 340 320 276 at break (%) Modulus 1890 1950 2100 2760 2430 3760 3870 of rupture (MPa)

(9) Other tests were carried out: the polyurethanes 1a and 3a were prepared from the same ingredients as the polyurethanes 1 and 3 respectively, but with a one-step process, that is to say that the 4,4-MDI and the XDI are introduced simultaneously with the polyols.

(10) The polyurethanes 1a and 3a were also characterized. The results are presented in table 2a below.

(11) TABLE-US-00004 TABLE 2a characterization of the polyurethanes 1a and 3a 1a 3a V(D + 1) V(D + 7) 30000 50000 Modulus at 100% 1110 1200 Elongation at break 290 340 Modulus of rupture 1950 2600 % by weight of final NCO 2.1 2.6

(12) It was moreover observed that the content of residual MDI and XDI monomers of the compositions of polyurethanes 1a and 3a is close to the content of residual MDI and XDI monomers of the compositions of polyurethanes 1 and 3 respectively.

Preparation of the Mastic Compositions

(13) Since the comparative examples B to D formed a gel, they were not able to be formulated into mastic compositions.

(14) Mastic compositions were then formulated from the polyurethanes A and 1 to 6 that were prepared in accordance with the process above.

(15) The mastic compositions were obtained by mixing the following ingredients: 20% by weight of the previously prepared polyurethane, 15.5% by weight of the plasticizer, 30% by weight of filler(s), 12% by weight of urea gel, 4.5% by weight of solvent, 16% by weight of PVC, 2% by weight of other additives.

(16) The mastic compositions formulated from each polyurethane were characterized as reported in table 3.

(17) TABLE-US-00005 TABLE 3 characterization of the mastic compositions A 1 2 3 4 5 6 Skinning 70 80 90 106 300 220 360 time (min) Extrusion 163 210 236 273 845 125 1500 (g/min) Cure 24 h (mm) 4 4 4 3 3 3 3 Dumbbell 460 500 540 560 430 740 666 Modulus at 100% (kPa) Dumbbell 946 846 811 818 774 718 710 Elongation at break (%) % free MDI 0.2 0.05 0.05 0.07 <0.01 <0.01 <0.01 % free XDI 0.10 0.12 0.16 0.29 0.30 0.36 Characterization: The skinning time was measured according to the standard ISO 291 at 23 C. and 50% relative humidity. The extrusion corresponds to the amount of mastic in grams that was able to be extruded per minute, under a piston pressure of 3 bar, at 23 C. The cure 24 h was measured according to the standard ISO 291. The dumbbell modulus at 100% was measured according to the standard NF ISO 37 (March 2012) with dumbbell test specimens. The dumbbell elongation at break was measured according to the standard ISO 37 (March 2012) with dumbbell test specimens. The % free MDI corresponds to the amount of residual MDI monomers in the mastic composition expressed as a weight percentage relative to the weight of the mastic composition. The % free XDI corresponds to the amount of residual XDI monomers in the mastic composition expressed as a weight percentage relative to the weight of the mastic composition.

(18) For compositions 4, 5 and 6, it is observed that the amount of residual MDI monomers is below the detection limit of the apparatus (0.01%).

(19) The comparative composition A comprises a polyurethane based on MDI alone and it is noted that the amount of residual MDI monomers is 0.2%, which is above the regulatory limit that requires products to be labeled.

(20) The compositions 1 to 5 according to invention have satisfactory properties for the targeted applications and furthermore they have residual MDI and XDI contents below the regulatory limits imposed for the labeling of the products.

(21) Moreover, it is noted that the compositions 1 to 3 have the closest properties to the properties of the comparative composition A.

(22) An XDI-terminated polyurethane based on XDI (composition 6) has a limited industrial advantage since the cost of XDI is high.

(23) Of course, the present invention is not limited to the examples and embodiments described and represented, but can be varied in numerous ways which are achievable by a person skilled in the art.