Aminosiloxanes of high purity

Abstract

Disclosed herein is a composition comprising amino-functional polysiloxanes of high purity and their preparation. Also disclosed herein is an aminoalkyl-functional polysiloxane, a process for purifying this aminoalkyl-functional polysiloxane, a process for preparing the composition, a use of the composition, a polyorganosiloxane-polyorgano block copolymer, a process for the preparation of a polyorganosiloxane-polyorgano block copolymer and a shaped, formed and/or extruded shaped article.

Claims

1. A composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 comprising: (A) at least one aminoalkyl-functional polysiloxane of general formula (I): ##STR00020## wherein R.sub.1 is independently selected from the group consisting of a monovalent linear alkyl, branched alkyl, arylalkyl, alkylaryl, and aryl groups containing up to 20 carbon atoms, each R.sub.2 is independently a linear or branched divalent C3 or C4 alkyl group, and n is an integer of from 0 to 7; and (B) at least one compound comprising at least one iminoalkyl functional group obtained from the hydrosilylation of at least one olefinic amine and at least one hydridosiloxane in the presence of a platinum catalyst, wherein the H.sub.2N-functionality is determined by .sup.1H NMR using the equation:
[H.sub.2N?functionity=2.0*(1?[mol % impurity?CH]/100, wherein the mole percent impurity-CH functionality is calculated from the corresponding area integral of the impurity (N?CH)-signals of the iminoalkyl groups, observed in the range of from 7.4 to 7.7 ppm versus the integrals of the SiCH.sub.n, where n is 1 or 2 observed in the range of from 0.4 to 0.7 ppm, and wherein the composition is made by a process comprising the steps of: (i) reacting a composition having an H.sub.2N-functionality of greater than 0 and less than 1.96 and/or color according to Hazen number of greater than 100 comprising at least one an aminoalkyl-functional polysiloxane and at least one compound comprising at least one iminoalkyl functional group with a stoichiometric excess, related to the content of H.sub.2N-groups, of an acid with a pKa less than or equal to 5.5 and a stoichiometric excess of water, related to the acid, to provide for a reaction product composition, (ii) removing the volatile compounds present in the reaction product composition of step (i) by distillation, optionally with the use of an inert carrier gas, at a temperature of from 40? C. to 250? C. and at a pressure of from 0.1 mbar to 1030 mbar to provide for a devolatilized higher boiling composition, (iii) neutralizing the resulting devolatilized higher boiling composition of step (ii) with at least one base to provide for a neutralized and devolatilized higher boiling composition, and (iv) depolymerizing the neutralized and devolatilized higher boiling composition of step (iii) in the presence of at least one base to produce a composition containing at least one amino-functional polysiloxane of formula (I), and (v) distilling the composition containing at least one amino-functional polysiloxane of step (iv) at a temperature of from 60? C. to 250? C. and at a pressure of from 0.1 mbar to 1030 mbar to provide for the composition comprising components (A) and (B) and having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00.

2. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein the at least one acid of reaction step (i) is hydrochloric acid.

3. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein the base catalyst in step (iv) is sodium hydroxide, potassium hydroxide, cesium hydroxide or their related silanolates.

4. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein the R.sub.1 groups are monovalent methyl or phenyl groups.

5. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein the R.sub.2 groups are CH.sub.2CH.sub.2CH.sub.2 or CH(CH.sub.3)CH.sub.2.

6. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein in process step (i) the aminoalkyl-functional polysiloxane has a color according to Hazen in the range of greater than 100 to 500.

7. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein in process step (i), wherein the excess of water to acid is in a range of from 3 moles of water to acid to 10 moles of water to acid.

8. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein in process step (i), the reaction temperature is controlled between 10-30 degrees Celsius.

9. The composition having a Hazen number of from 0 to 100 and a H.sub.2N-functionality of from 1.96 to less than 2.00 according to claim 1, wherein in process step (iv) the base used is the base from step (iii).

Description

EXAMPLES

(1) Unless explicitly stated differently, all percentages given are weight percentages. The given NH.sub.2-functionalities were determined by .sup.1H-NMR as described above. This means that a 500 MHz .sup.1H-NMR spectrum of product in CDCl.sub.3 was used. The signal at 7.4 to 7.7 ppm referring to the impurity was integrated using the limits exactly set to 7.4 to 7.7 ppm. Moreover, the peak at 0.46 ppm was integrated using limits exactly set to 0.3 to 0.6 ppm and the integral was set to 1.0000. Finally, the peak at 0.67 ppm was integrated using the limits exactly set to 0.6 to 0.75 ppm. The mol-% impurity-CH was calculated using the above-shown formula, the result of which was then used to determine the NH.sub.2-functionality using the above-shown formula.

Example 1

(2) 250 g of a linear aminopropyl-functional polydimethylsiloxane with an amine content of 2.6 mmolNH.sub.2/g (650 mmol NH.sub.2), a Hazen color value of 146 and 2.5 mole-% of iminoalkyl groups and a NH.sub.2-functionality of 1.95 based upon the total amine content and 40 g of water were charged to a 500 ml reactor equipped with a dropping funnel, a thermometer, condenser with distillation receiver. The dropping funnel was charged with 60 g of water and 72 g of 35% aqueous hydrochloric acid (681 mmol HCl, 105 mole-%) and the whole apparatus was placed under a nitrogen atmosphere. The HCl/water solution was added to the reactor over 25 minutes at a temperature of below 30? C. Then 40 g of Dowanol PM was added and the reaction mixture was agitating for 1 hour. The product was stripped applying heat and vacuum until achieving 100? C. and 15 mbar and holding these conditions for 1 hour. The reactor was cooled to 55? C. Then 100 g water and 95 g of 40% potassium hydroxide solution were added. After agitation for 1 hour the two-phase mixture was allowed to settle and the lower phase was decanted. This neutralized siloxane was highly colored and essentially free of all iminopropyl groups.

(3) To the neutralized siloxane was added 4 g of 40% potassium hydroxide solution and the reaction heat and vacuum were applied for fractional distillation. The distillation fraction obtained between 55 and 104? C. at 2-3 mbar was collected. This fraction consisted of 135 g of a colorless and essentially iminoalkyl-free mixture of aminopropylsiloxanes and cyclodimethylsiloxanes with an amino-content of 2.84 mmol NH.sub.2/g (81.7 mole-% yield) and a NH.sub.2-functionality of 1.99.

Example 2

(4) To 118 g of the mixture of aminopropylsiloxanes and cyclodimethylsiloxanes from Example 1 and 52.5 g of additional octamethylcyclotetrasiloxane was added 3.4 g of tetramethylammonium siloxanoate with about a 2.8% tetramethylammonium content and the reaction was placed under a nitrogen atmosphere. The reaction mixture was heated to 80? C. for 8 hours with agitation. The catalyst was then deactivated by heating to 150? C. for 1 hour. Finally the reaction mixture was stripped of excess cyclosiloxanes to 140? C. and <1 mbar and filtered to obtain 148 g of a aminopropyl-functional polydimethylsiloxane with 1.94 mmolNH.sub.2/g, a Hazen color value of 23, a viscosity of 14.6 mPa*s at 25? C., and according to .sup.1H NMR an iminoalkyl content of 0.08 mole-% and a NH.sub.2-functionality of 1.9984.

Example 3

(5) 250 g of a linear aminopropyl-functional polydimethylsiloxane with an amine content of 2.11 mmolNH.sub.2/g, a Hazen color value of 413 and 7.5 mole-% of iminoalkyl groups and a NH.sub.2-functionality of 1.85 was treated with acid as in Example 1 to yield after reaction with additional octamethylcyclotetrasiloxane as in Example 2 an amount of 196 g aminopropyl-functional polydimethylsiloxane with 2.04 mmolNH.sub.2/g, a Hazen color value of 37, a viscosity of 14.3 mPa*s at 25? C., and an iminoalkyl content according to .sup.1H NMR of 0.2 mole-% and a NH.sub.2-functionality of 1.996.

(6) As can be seen from the results of examples 1 to 3 an amino-functional polysiloxane can be obtained which has a higher purity than the respective educt. The iminoalkyl content in the educt has been significantly reduced using the process steps according to the present invention. Moreover, the products are essentially free of color. They can be obtained in a good yield.

Example 4 (Comparative Example)

(7) 168.7 g of a hydride terminated polydimethylsiloxane with a content of 2.47 mmol (SiH)/g and 31.3 g of allyl amine (0.55 mol) were charged to a 500 ml reactor equipped with a thermometer, condenser with distillation receiver and placed under an inert atmosphere. 1.2 g (60 ppm Pt) of a 1% solution in xylenes of the Pt(0) complex of tetravinyltetramethylcyclotetrasiloxane as described in U.S. Pat. No. 6,177,583 was added and the reaction was heated to 60? C. for 3 hours. A control sample determined that there was 100% conversion of the SiH groups. The reaction product was then stripped to 150? C. and <20 mbar, holding for 1 hour, cooled to ambient temperature and filtered over a Seitz K300 filter to yield 125 g of an aminopropyl-functional polydimethylsiloxane with a viscosity at 25? C. of 11.6 mPa*s, a Hazen color value of 454, an amine content of 2.03 mmol NH.sub.2/g. According to .sup.1H NMR the product had a content of 7.5 mole-% iminoalkyl groups and a NH.sub.2-functionality of 1.85.

Example 5 (Comparative Example)

(8) 151.4 g of a hydride terminated polydimethylsiloxane with a content of 2.8 mmol (SiH)/g and 48.5 g of allyl amine (0.85 mol) were charged to a 500 ml reactor equipped with a thermometer, condenser with distillation receiver and placed under an inert atmosphere. 0.6 g (30 ppm Pt) of a 1% solution in xylenes of the Pt(0) complex of tetravinyltetramethylcyclotetrasiloxane as described in U.S. Pat. No. 6,177,583 was added and the reaction was heated to 60? C. and held at reflux 6 hours. During the reaction the temperature rose to 75? C. A control sample determined that there was 100% conversion of the Sill groups. The reaction product was then stripped to 150? C. and <20 mbar, holding for 1 hour, cooled to ambient temperature and filtered over a Seitz K300 filter to yield 163 g of an aminopropyl-functional polydimethylsiloxane with a viscosity at 25? C. of 10.7 mPa*s, a Hazen color value of 181, an amine content of 2.26 mmol NH.sub.2/g. According to .sup.1H NMR the product had a content of 6.3 mole-% iminoalkyl groups and a NH.sub.2-functionality of 1.874.

(9) Repeating these experiments under various reaction conditions, including the use of polar solvents, such as toluene or 2-methoxypropanol, and other catalysts such as the Pt(0) complex of divinyltetramethyldisiloxane also described in U.S. Pat. No. 6,177,583 or hexachloroplatinic acid or the platinum catalyst according to U.S. Pat. No. 3,220,972, or Pt(NH.sub.3).sub.2Cl.sub.2, always yielded products with at least 3.0 mole-% iminoalkyl groups or a NH.sub.2-functionality of less than 1.94.

Example 6 (Comparative Example)

(10) 100 g of a linear aminopropyl-functional polydimethylsiloxane with an amine content of 2.14 mmolNH.sub.2/g and 5.31 mole-% of iminoalkyl groups was treated with 40 g toluene, 40 g water and 2 g of acid activated clay (Tonsil CO 614G, Clariant) according to GB 2,185,984 to obtain an isolated aminosiloxane with a 5.15 mole-% iminoalkyl content and a NH.sub.2-functionality of 1.897.

Example 7 (Comparative Example)

(11) 100 g of a linear aminopropyl-functional polydimethylsiloxane with an amine content of 2.14 mmolNH.sub.2/g (214 mmol NH.sub.2) and 5.31 mole-% of iminoalkyl groups was reacted with 60 g water and 10 g 35% aqueous hydrochloric acid (95 mmol HCl, 44 mole-%), but otherwise as in Example 1, to yield after neutralization an aminosiloxane with 4.47 mole-% iminoalkyl content and a NH.sub.2-functionality of 1.91.

(12) While the invention has been described above with references to specific embodiments thereof, it is apparent that many changes, modifications and variations can be made without departing from the invention concept disclosed herein. Accordingly, it is intended to embrace all such changes, modifications, and variations that fall within the spirit and broad scope of the appended claims.