NON-HOT-MELT MDI-BASED POLYURETHANE COMPOSITION BEARING NCO END GROUPS AND HAVING A LOW CONTENT OF MDI MONOMER, COMPRISING AT LEAST ONE ISOCYANATE COMPOUND OF PARTICULAR MOLAR VOLUME

Abstract

1) Polyurethane composition comprising: a) at least 98% by weight of at least one non-hot-melt polyurethane bearing NCO end groups based on diphenyl methane diisocyanates (MDI), b) a MDI monomer content of less than or equal to 1% by weight, c) at least one particular isocyanate compound with a molar volume of less than or equal to 300 millilitres per mole.

2) Process for preparing a polyurethane composition as defined previously, and an adhesive, mastic and/or surface coating composition formulated from such a polyurethane composition.

Claims

1. Polyurethane composition comprising: a) at least 98% by weight of at least one non-hot-melt polyurethane bearing NCO end groups based on diphenylmethane diisocyanate (MDI), b) a content of MDI monomer of less than or equal to 1% by weight, c) at least one isocyanate compound with a molar volume of less than or equal to 300 millilitres per mole (mL/mol) (noted compound (A)), chosen from those in which the isocyanate group(s) are not linked to a carbon atom of an aromatic hydrocarbon-based ring, and those which are different from the polyisocyanate(s) used for the synthesis of the MDI-based polyurethane bearing NCO end groups mentioned in a), the weight percentages being expressed relative to the total weight of the polyurethane composition.

2. Composition according to claim 1, characterized in that the compound(s) (A) are chosen from monoisocyanates and diisocyanates.

3. Composition according to claim 1, characterized in that compound (A) is chosen from XDI, HMDI and IPDI.

4. Composition according to claim 1, characterized in that it comprises a total content of compound(s) (A) which is non-zero and less than 1.5% by weight relative to the weight of said composition.

5. Composition according to claim 1, characterized in that the non-hot-melt polyurethane(s) bearing NCO end groups based on MDI may be obtained via a polyaddition reaction of a polyisocyanate composition consisting of MDI, and of a composition consisting of polyol(s), at a temperature of less than 95 C., under anhydrous conditions, in amounts of polyisocyanate(s) and of polyol(s) leading to an NCO/OH ratio noted r1 ranging from 1.60 to 1.95.

6. Composition according to claim 5, characterized in that the temperature ranges from 70 to 80 C. and the NCO/OH ratio noted r1 ranges from 1.60 to 1.75.

7. Composition according to claim 5, characterized in that the composition consisting of polyol(s) is a mixture of polyether diol and polyether triol.

8. Composition comprising: from 10% to 30% by weight of a polyurethane composition as defined 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 weight percentages being expressed relative to the total weight of the composition.

9. Process for preparing a composition as defined in claim 1, comprising a step in which the compound(s) (A) and the other ingredient(s) optionally present in said composition, are mixed with a polyurethane composition comprising at least one an polyurethane bearing NCO end groups based on MDI, which is not solid at a temperature ranging from 5 to 35 C., and a MDI content of less than or equal to 1% by weight relative to the weight of said polyurethane composition, at a temperature of less than or equal to 50 C., under anhydrous conditions in post-synthesis of said MDI-based polyurethane bearing NCO end groups.

10. Process according to claim 9 characterized in that the compound(s) (A) are mixed with said composition: either directly after the end of the reaction for the synthesis of the polyurethane bearing NCO end groups based on MDI as defined in claim 9, or after one, several or all of the other ingredients of the composition have been mixed with the polyurethane bearing NCO end groups based on MDI as defined in claim 9.

11. A process for stabilizing the viscosity of a composition comprising at least one polyurethane based on MDI bearing NCO end groups, which is not solid at a temperature ranging from 5 to 35 C., and a MDI content of less than or equal to 1% by weight relative to the weight of said composition, comprising adding at least one isocyanate compound with a molar volume of less than or equal to 300 millilitres per mole other than MDI.

Description

EXAMPLES

Preparation of the Polyurethane Compositions: Examples 1 to 3 (Reference)

[0204] The polyurethane compositions of Examples 1 to 3 were prepared by mixing the ingredients indicated in Table 1 at a temperature of less than or equal to 95 C. under anhydrous conditions. The amounts indicated in Table 1 are expressed as weight percentages relative to the total weight of the polyurethane composition of each of the examples.

TABLE-US-00001 TABLE 1 Ingredients 1 2 3 PPG triol with a number-average molar mass 49.5 50.5 51.3 of 4000 g/mol PPG diol with a number-average molar mass 32.5 33.2 33.6 of 2000 g/mol 4,4-MDI (% NCO = 33.6% by weight) 18.1 16.2 15 Catalyst 0.1 0.1 0.1 NCO/OH ratio 2.01 1.78 1.61

Characterization:

[0205] For each of the polyurethane compositions of Examples 1 to 3 obtained: [0206] The weight content of unreacted diisocyanate monomer present in the polyurethane synthesis medium is measured via an HPLC method equipped with a UV detector as described previously (C18 reverse phase, mobile phase: aqueous solution of acetonitrile, buffered with an aqueous solution containing 0.2% by weight of tetrabutylammonium bisulfate at a pH equal to 2.5, detection wavelength: 254 nm). The values measured are expressed as a weight percentage relative to the weight of the composition of each of Examples 1 to 3. [0207] The viscosity of the polyurethane composition is measured at the end of reaction (D) and then 30 days after the end of the reaction (D+30) at 23 C. under anhydrous storage conditions. It is considered that after 30 days, the increase in viscosity over time of the polyurethane is negligible. The viscosity measurement is taken at 23 C. using a Brookfield RVT viscometer, with a number 6 needle at a spin speed of 20 revolutions per minute (rpm). The value measured is expressed in millipascal-seconds (mPa.Math.s).

TABLE-US-00002 TABLE 2 Characterization before stabilization 1 2 3 Residual MDI content calculated >1 <0.8 <0.5 (in % by weight relative to the weight of the polyurethane composition) Viscosity at 23 C. (mPa .Math. 5500 5800 5200 s) (D) Viscosity at 23 C. (mPa .Math. 87 000 300 000 300 000 s) (D + 30)

[0208] It is observed that after 30 days of storage under conditions identical to those mentioned above, the polyurethane compositions of Examples 2 and 3 obtained with a residual MDI monomer content of less than or equal to 1% by weight relative to the weight of the polyurethane composition have a viscosity about 3.5 times greater than that measured on the polyurethane composition of Example 1 obtained with a residual MDI monomer content of greater than 1% by weight relative to the weight of the polyurethane composition.

[0209] The viscosity of a polyurethane composition comprising a residual MDI monomer content of less than or equal to 1% by weight relative to the weight of the polyurethane composition thus changes more rapidly than that of a polyurethane composition comprising more than 1% by weight of residual MDI monomer relative to the weight of the polyurethane composition.

[0210] Stabilization of the Polyurethane Composition of Example 2: Examples 2A to 2I

[0211] The compositions of Examples 2A to 2I are prepared by mixing the polyurethane composition of Example 2 (noted polyurethane 2) and a compound (A) of molar volume less than or equal to 300 mL/mol in accordance with the invention, or an isocyanate with a molar volume of greater than 300 mL/mol for comparative purposes. The nature and amounts of the ingredients used are indicated in Table 3 below. The amounts given in Table 3 are expressed in grams relative to the weight of the composition.

Characterization:

[0212] For each of the compositions of Examples 2A to 2F, the effect of adding a compound (A) with a molar volume of less than or equal to 300 mL/mol to the polyurethane composition of Example 2 judged as being unstable in terms of viscosity was evaluated.

[0213] For comparative purposes, for each of the compositions of Examples 2G to 2I, the effect of adding an isocyanate with a molar volume of greater than 300 mL/mol to the polyurethane composition of Example 2 judged as being unstable in terms of viscosity was evaluated.

[0214] For each of the compositions 2A to 2I, the percentage of stabilization observed at D+30 corresponding to the reduction in viscosity measured at 23 C., 30 days after adding the isocyanate compound to the polyurethane composition was calculated relative to the viscosity of the same composition not stabilized (composition of Example 2) observed at the same period and under the same conditions. This viscosity reduction is calculated via the following formula and is expressed as a percentage:

[00001]$100-\left(\frac{\mathrm{viscosity}.Math..Math.\mathrm{of}.Math..Math.\mathrm{the}.Math..Math.\mathrm{composition}.Math..Math.\mathrm{of}.Math..Math.\mathrm{Example}.Math..Math.2}{\begin{array}{c}\mathrm{viscosity}.Math..Math.\mathrm{of}.Math..Math.\mathrm{the}.Math..Math.\mathrm{composition}.Math..Math.\mathrm{of}\\ \mathrm{Example}.Math..Math.2.Math.i.Math..Math.\left(\mathrm{with}.Math..Math.i.Math..Math.\mathrm{ranging}.Math..Math.\mathrm{from}.Math..Math.A.Math..Math.\mathrm{to}.Math..Math.I\right)\end{array}.Math.}100\right)$

[0215] When the addition of the isocyanate compound leads to a reduction in viscosity relative to the reference viscosity of Example 2, the percentage stabilization value is preceded by the sign + indicating a gain in stability relative to the reference (consisting of the composition of Example 2).

[0216] In the opposite case, the percentage stabilization value is preceded by the sign indicating a loss of stability relative to said reference.

[0217] The viscosity measurements are performed under the same measuring conditions (apparatus and time) and storage conditions (anhydrous conditions) as previously for Examples 1 to 4. The results are indicated in Table 3 below.

Results:

[0218] It is observed that after 30 days of storage under conditions identical to those mentioned above, the compositions of Examples 2A to 2F according to the invention comprising a compound (A) with a molar volume of less than or equal to 300 mL/mol show a significant reduction in viscosity (in particular greater than or equal to 50%) relative to the viscosity measured on the non-stabilized polyurethane composition of Example 2.

[0219] On the other hand, it is observed that after 30 days of storage, the compositions of Comparative Examples 2G to 2I comprising a diisocyanate with a molar volume of greater than 300 mL/mol do not show any significant reduction in viscosity (less than or equal to 5%) relative to the viscosity measured on the non-stabilized polyurethane composition of Example 2.

[0220] Stabilization of the Polyurethane Composition of Example 3: Examples 3A to 31

[0221] The compositions of Examples 3A to 31 are prepared by mixing the polyurethane composition of Example 3 (noted polyurethane 3) and a compound (A) with a molar volume of less than or equal to 300 mL/mol in accordance with the invention, or a diisocyanate with a molar volume of greater than 300 mL/mol for comparative purposes. The nature and amounts of the ingredients used are indicated in Table 4 below. The amounts given in Table 4 are expressed in grams relative to the weight of the composition.

Characterization:

[0222] For each of the compositions of Examples 3A to 3F, the effect of adding a compound (A) with a molar volume of less than or equal to 300 mL/mol to the polyurethane composition of Example 3 judged as being unstable in terms of viscosity was evaluated.

[0223] For comparative purposes, for each of the compositions of Examples 3G to 31, the effect of adding a diisocyanate with a molar volume of greater than 300 mL/mol to the polyurethane composition of Example 3 judged as being unstable in terms of viscosity was evaluated.

[0224] The viscosity measurements are performed under the same measuring and storage conditions as previously for Examples 1 to 4. The results are indicated in Table 4 below. The stabilization value expressed as a % is deduced therefrom as previously. The comparison is made this time relative to the viscosity of the reference composition, consisting of the composition of Example 3.

Results:

[0225] It is observed that after 30 days of storage under the abovementioned conditions, the compositions of the examples according to the invention 3A to 3F comprising a compound (A) with a molar volume of less than or equal to 300 mL/mol show a significant reduction in viscosity (in particular greater than or equal to 30%) relative to the viscosity measured on the non-stabilized polyurethane composition of Example 3.

[0226] On the other hand, it is observed that after 30 days under the abovementioned storage conditions, the compositions of Comparative Examples 3G to 31 comprising a diisocyanate with a molar volume of greater than 300 mL/mol do not show a significant reduction in viscosity (less than or equal to 5%) relative to the viscosity measured on the non-stabilized polyurethane composition of Example 3.

[0227] Examples of Stabilization of Mastic Compositions

[0228] The stabilizing effect of the addition of a compound A according to the invention to two different mastic compositions was tested, each composition comprising: [0229] from 20% to 30% by weight of a composition comprising at least 98% by weight of an MDI-based non-hot-melt polyurethane bearing NCO end groups with an MDI content such that the MDI content relative to the weight of the mastic composition is less than 0.1% by weight, [0230] from 20% to 25% by weight of carbonated filler, [0231] from 10% to 20% by weight of organic filler and/or rheology agent, [0232] from 0.01% to 1% by weight of a crosslinking catalyst.

[0233] For each of the mastic compositions tested, 0.1 g of XDI was added to 100 g of mastic composition, at a temperature of less than or equal to 50 C. and under anhydrous conditions.

[0234] Immediately after the end of mixing (t0) and 3 weeks after the end of mixing (t+3 weeks), the mastic compositions are extruded through an extrusion nozzle 4 mm in diameter under a pressure of 3 bar at constant temperature and hygrometry so as to evaluate their viscosity.

[0235] The viscosity measurement (in millipascal-seconds (mPa.Math.s)) is performed at 23 C. at t0 and t+3 weeks using a Brookfield RVT viscometer, with a number 6 needle at a spin speed of 20 revolutions per minute (rpm).

[0236] For each of the mastic compositions tested, the improvement in the extrusion rate, expressed as a percentage, observed at t0 and at t+3 weeks following the addition of XDI was calculated relative to the rate observed without XDI stabilization.

[0237] It was observed that the addition of 0.1% of XDI to the mastic compositions led to satisfactory extrusion rates (greater than or equal to 70 g/mn) and better than those measured on the mastic compositions without XDI. A gain in extrusion rate of the order of 60% to 85% is observed relative to the non-stabilized mastic compositions, reflecting better stability in terms of viscosity of the stabilized mastic compositions according to the invention.

TABLE-US-00003 TABLE 3 Examples 2 2A 2B 2C 2D 2E Ingredients reference invention Polyurethane 2 100 100 100 100 100 100 XDI 0.1 0.4 (molar volume = 157 mL/mol) IPDI 0.1 0.4 (molar volume = 212 mL/mol) HMDI 0.1 (molar volume = 246 mL/mol) Diisocyanate (molar volume = 621 mL/mol) Residual MDI content calculated 0.8 0.8 0.8 0.8 0.8 0.8 (in % by weight relative to the weight of the polyurethane composition) Viscosity at 23 C. (mPa .Math. s) (D) 5800 5160 4640 5040 5100 4820 Viscosity at 23 C. (mPa .Math. s) (D + 30) 300000 109000 100000 140000 130000 125000 Stabilization (at D + 30) relative 0% +63.7% +66.7% +53.3% +56.7% +58.3% to the reference composition Examples 2F 2G 2H 2I Ingredients invention comparative Polyurethane 2 100 100 100 100 XDI (molar volume = 157 mL/mol) IPDI (molar volume = 212 mL/mol) HMDI 0.4 (molar volume = 246 mL/mol) Diisocyanate 0.1 0.4 1 (molar volume = 621 mL/mol) Residual MDI content calculated 0.8 0.8 0.8 0.8 (in % by weight relative to the weight of the polyurethane composition) Viscosity at 23 C. (mPa .Math. s) (D) 4800 4890 4960 5100 Viscosity at 23 C. (mPa .Math. s) (D + 30) 115000 290000 310000 315000 Stabilization (at D + 30) relative +61.7% +3.3% 3.3% 5.0% to the reference composition

TABLE-US-00004 TABLE 4 Examples 3 3A 3B 3C 3D 3E Ingredients reference invention Polyurethane 3 100 100 100 100 100 100 XDI 0.3 0.8 (molar volume = 157 mL/mol) IPDI 0.3 0.8 (molar volume = 212 mL/mol) HMDI 0.3 (molar volume = 246 mL/mol) Diisocyanate (molar volume = 621 mL/mol) Residual MDI content calculated 0.5 0.5 0.5 0.5 0.5 0.5 (in % by weight relative to the weight of the polyurethane composition) Viscosity at 23 C. (mPa .Math. s) (D) 5200 4800 4400 4800 4600 4800 Viscosity at 23 C. (mPa .Math. s) (D + 30) 300000 170000 130000 200000 180000 180000 Stabilization (at D + 30) relative 0% +43.3% +56.7% +33.3% +40% +40% to the reference composition Examples 3F 3G 3H 3I Ingredients invention comparative Polyurethane 3 100 100 100 100 XDI (molar volume = 157 mL/mol) IPDI (molar volume = 212 mL/mol) HMDI 0.8 (molar volume = 246 mL/mol) Diisocyanate 0.1 0.4 1 (molar volume = 621 mL/mol) Residual MDI content calculated 0.5 0.5 0.5 0.5 (in % by weight relative to the weight of the polyurethane composition) Viscosity at 23 C. (mPa .Math. s) (D) 4400 5600 4900 4650 Viscosity at 23 C. (mPa .Math. s) (D + 30) 130000 315000 289000 298000 Stabilization (at D + 30) relative +56.7% 5.0% +3.7% +0.7% to the reference composition

[0238] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

[0239] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.