Process for preparing organopolysiloane gels

Abstract

Storage stable organopolysiloxane gels, preparable in commercial quantities are prepared by the hydrosilylation reaction of a silicone resin containing a hydrosilyatable group, a short chain Si—H-functional silicone, and a long chain Si—H-functional silicone.

Claims

1. A process for producing organopolysiloxane gels, comprising: reacting (1a) unsaturated organopolysiloxane resins comprising units of the formulae
SiO.sub.2(Q units) and
R.sub.3SiO.sub.1/2 and R.sub.2R.sup.1SiO.sub.1/2(M units), where R each independently is a monovalent, optionally substituted hydrocarbon radical having 1 to 18 carbon atoms per radical, R.sup.1 each independently is a monovalent hydrocarbon radical onto which Si-H groups are optionally added in a hydrosilylation reaction, with the proviso that the organopolysiloxane resins contain at least 2 R.sup.1 radicals, and that the molar ratio of M units to Q units is in the range from 0.5 to 4.0, the organopolysiloxane resins optionally containing, in addition to the M and Q units, small amounts of RSiO.sub.3/2 (T) units and/or R.sub.2SiO.sub.2/2 (D) units, in amounts of 0.01 to 20 mol %, based on the sum total of all siloxane units, the organopolysiloxane resins optionally containing up to 10% by weight of Si-bonded hydroxyl or alkoxy groups, and optionally (1b) compounds having a polar organic group and a hydrosilylatable end group, with (2) a mixture of two Si-H-containing organopolysiloxanes which have different average chain lengths, of the formula:
(R.sup.2.sub.3-xH.sub.xSiO.sub.1/2) (R.sup.2.sub.2SiO.sub.2/2).sub.a(R.sup.2HSiO.sub.2/2).sub.b(R.sup.2.sub.3-xH.sub.xSiO.sub.1/2)  (I) where R.sup.2 each independently is an unsubstituted or optionally heteroatom-substituted, aliphatic, cycloaliphatic or aromatic, optionally polycyclic, C.sub.1-C.sub.18 hydrocarbon radical, x is 0 or 1, a and b are each integers ≥0, with the provisos that the sum total of a+b ≥30, that the organopolysiloxanes contain an average of at least 2 Si-bonded hydrogen atoms, and that the long-chain organopolysiloxane has at least 3 times the chain length (a+b) of the short-chain organopolysiloxane, in the presence of (3) catalysts that promote the addition of Si-bonded hydrogen onto aliphatic multiple bonds, where (1a), optionally (1b) and (2) is/are dispersed in (4) diluents and the reaction is stopped by addition of (5) stopper compounds used as catalyst poisons.

2. The process of claim 1, wherein x=0 in formula (I).

3. The process of claim 1, wherein the sum of a+b >55 in the formula (I).

4. The process of claim 1, wherein catalysts (3) are metal catalysts in amounts of 1 to 100 ppm by weight (parts per weight per million parts by weight), calculated as elemental metal, based in each case on the total weight of components (1a), optionally (1b) and (2).

5. The process of claim 1, wherein at least one diluent (4) is a polydimethylsiloxane having 2 to 50 silicon atoms, an aliphatic or alicyclic hydrocarbons having 4 to 30 carbon atoms, or an ester of a carboxylic acid having 2 to 30 carbon atoms.

6. The process of claim 1, wherein at least one stopper compound (5) is an organic compound having mercapto groups (SH) or an organopolysiloxane having mercaptoalkyl groups.

7. The process of claim 1, wherein the stopper compounds (5) are used in amounts of at least 1.1 mol of functional group that brings about the stopping per mole of elemental metal.

8. The process of claim 1, wherein the organopolysiloxane gels obtained after the reaction are homogenized to obtain organopolysiloxane gels which do not separate into two or more phases in the course of storage at room temperature (20° C.) for six months.

9. The process of claim 1, wherein the organopolysiloxane gels obtained are diluted with further diluents (4) and/or active ingredients for personal care or healthcare and then optionally homogenized.

10. A cosmetic composition comprising an organopolysiloxane gel produced according to claim 1.

Description

EXAMPLES

(1) The examples which follow serve to further illustrate the invention and describe its function and use in practice. In this regard, they should be considered to be illustrative and not restrictive.

(2) The examples state physical parameters that have been determined by the test methods described hereinafter. If there are no details in the example text as to the exact traceability of measurement, these are already given in the descriptions of the test methods that follow here. In other words, in this case, further details are considered to be those given in the texts for the test methods.

Analytical Methods

(3) The viscosity of the organopolysiloxane gels was determined in accordance with DIN EN ISO 3219 at a shear rate of 1/s and 25° C.

(4) The viscosity of the organopolysiloxanes, such as Si—H-containing crosslinkers, organopolysiloxane resins and polydimethylsiloxanes, was determined in accordance with DIN 53019 in the linear range at 25° C.

(5) The iodine number was determined in accordance with DIN 53241-1 by the method according to Wijs.

(6) Gel permeation chromatography to determine the weight-average molecular weight Mw was conducted in accordance with ISO 16014-1 and ISO 16014-3.

(7) The organopolysiloxane gels of the invention result in sensory advantages in cosmetic applications in that they improve the distributability of the product on the skin and impart a silky-smooth feel to the product. The organopolysiloxane gels are comparable in terms of their performance only when they are adjusted to a uniform viscosity for sensory testing. A particularly advantageous viscosity for this purpose has been found to be in the range of 75,000-120,000 mPas at 25° C. A criterion for the successful production of the organopolysiloxane gels is therefore the possibility of establishing this viscosity corridor. If this is not possible, there is no comparability with the other organopolysiloxane gels. It is a particular characteristic of the process of the invention that it permits the establishment of a target viscosity, such as 75,000-120,000 mPas here, independently of the process with retention of the sensory properties. This is demonstrated in the examples which follow and this property is delimited from the rest of the prior art.

(8) The sensory properties of the organopolysiloxane gels described in the examples below were assessed by a trained group of 5 testers (panelists).

(9) The panelists applied 0.05 g in each case of the product to the cleaned lower arm over a circular area of 20 cm.sup.2, and the organopolysiloxane gels were compared with respect to their distributability relative to one another. The application was effected with the index finger or middle finger and a speed of rotation of two revolutions per second. A total of 30 revolutions were conducted. After a wait time of 60 seconds, the residues of the organopolysiloxane gels were compared with respect to their silkiness relative to one another.

(10) Relative direct comparability is always possessed here solely by the organopolysiloxane gels that have been produced using the same or at least an equivalent diluent, i.e. more particularly with a volatile or nonvolatile diluent. Since different diluents result in different behavior on application and in terms of the residue, products having different diluents have to be assessed separately from one another in each case.

Example 1 (Inventive)

(11) A 2000 mL glass reaction vessel is equipped with a condenser with attached nitrogen inlet, heating mantle, anchor stirrer and closed-loop temperature controller. The reaction vessel is charged with 497 g of a linear trimethylsilyl-terminated polydimethylsiloxane having a viscosity of 5 mPas at 25° C. Thereafter, 82 g of short-chain Si—H-containing polydimethyl-siloxane number 14 from table 1 (chain length 140) and 20 g of long-chain Si—H-containing polydimethylsiloxane number 28 from table 2 (chain length 450) are added.

(12) Then 109.55 g of a 50% solution of an MQ resin (M/M.sup.vi/Q=7.6/1/11.4; M.sub.n=2570, M.sub.w=5440, iodine number=18; M=Me.sub.3SiO.sub.1/2, M.sub.vi=Me.sub.2ViSiO.sub.1/2, Q=SiO.sub.4/2 with Me=methyl radical and Vi=vinyl radical) in the same linear trimethylsilyl-terminated polydimethylsiloxane having a viscosity of 5 mPas at 25° C. which is also used as diluent are added. Lastly, 0.7 g of a mixture of platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in divinyltetra-methyldisiloxane is added, with adjustment of the mixture such that the amount added corresponds to 52 ppm by weight of Pt, based on the sum total of the mass of the MQ resin and the two Si—H-containing organopolysiloxanes. The reaction vessel is closed and purged with nitrogen for 5 min.

(13) Subsequently, the reaction mixture is heated to 95° C. at a stirrer speed of about 200 rpm, employing a heating rate of 45° C./h. Gel formation takes place within 30 minutes after the internal temperature of 95° C. has been attained. On completion of gel formation, the heating is switched off and the mixture is stirred for a further 60 minutes.

(14) Thereafter, 5.83 g of polydimethylsiloxane having 3-mercaptopropyl groups and a viscosity of 190 mPas at 25° C. and a mercaptan content (SH content) of 0.29% by weight are added as stopper. The amount of mercaptan that was added in this way corresponds to 108 ppm by weight, based on the total amount of Si—H-containing organopolysiloxanes and MQ resin, and is thus more than twice as large as the amount of platinum used.

(15) In addition, 89.68 g of the polydimethylsiloxane used as diluent having a viscosity of 5 mPas at 25° C. are added, and the stopper and the further diluent are stirred in while tilting by an ULTRA-TURRAX® T 50 at 6000 rpm for 5 minutes. This operation is repeated twice more with the same amount of diluent each time. No further stopper is added here. In this way, a creamy, transparent gel with very smooth consistency is obtained, which is suitable for use in cosmetic products.

(16) The solids content, i.e. the total content of network of MQ resin and the two Si—H-containing organopolysiloxanes, and also the stopper and the catalyst in the diluent, after dilution is 16% by weight.

(17) The organopolysiloxane gel obtained has a viscosity of 117,000 mPas at 25° C.

(18) According to the assessment by the panelists, the organopolysiloxane gel obtained has very good distributability.

(19) The residue was classified as plentiful and by the majority as predominantly silky and velvety.

Example 2 (Inventive)

(20) The procedure corresponds to that described in example 1, with the difference that, in example 2, rather than the nonvolatile linear diluent, volatile decamethylpentacyclosiloxane is used as diluent.

(21) After diluting to a solids content of 16% by weight, the viscosity is 152,000 mPas at 25° C.

(22) According to the assessment by the panelists, the organopolysiloxane gel obtained has very good distributability. The residue was classified as plentiful and by the majority as dry, silky and velvety.

Example 3 (Inventive)

(23) The procedure corresponds essentially to that described in example 1. By contrast with example 1, the diluent used, rather than a nonvolatile trimethylsilyl-terminated linear polydimethylsiloxane having a viscosity of 5 mPas at 25° C., is a volatile trimethylsilyl-terminated linear polydimethylsiloxane having a viscosity of 2 mPas at 25° C. The amount of diluent initially charged in the reaction vessel is 425.0 g. Rather than short-chain Si—H-containing polydimethylsiloxane number 14 from table 1, 67.75 g of short-chain Si—H-containing polydimethylsiloxane number 11 from table 1 (chain length 75) are weighed in and 20.0 g of long-chain Si—H-containing polydimethylsiloxane number 28 from table 2 (chain length 450) are added. 100.0 g of the same MQ resin formulation as used in example 1 are added. Lastly, 3.0 g of a mixture of platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in divinyltetramethyldisiloxane diluted with the trimethylsilyl-terminated polydimethylsiloxane having viscosity 2 mPas at 25° C. are added, with adjustment of the mixture such that the amount added corresponds to 26 ppm by weight of Pt, based on the sum total of the mass of the MQ resin and the two Si—H-containing polydimethylsiloxanes.

(24) The further procedure corresponds to that described in example 1. For stopping, 2.0 g of polysiloxane having 3-mercaptopropyl groups and a viscosity of 190 mPas at 25° C. and a mercaptan content (SH content) of 0.29% by weight are added as stopper. The amount of mercaptan that was added in this way corresponds here to 42 ppm by weight, based on the total amount of Si—H-containing polydimethylsiloxanes and MQ resin, and thus corresponds to 1.6 times the amount of platinum used. This base gel is then diluted by adding 57.75 g of further diluent in the first dilution step, 67.54 g in the second step and 104.3 g in the third step. The procedure in the dilution corresponds to the same as described in example 1.

(25) The final solids content, i.e. the content of network formed from the Si—H-containing polydimethylsiloxanes and the MQ resin together with the amount of catalyst used and the stopper oil, is 16% by weight. The following viscosities were measured during the dilution:

(26) Before the first dilution: solids content: 22.5%: 344,000 mPas

(27) After the first dilution: solids content: 20.5%: 258,000 mPas

(28) After the second dilution: solids content: 18.5%: 169,000 mPas

(29) After the third dilution: solids content: 16%: 91,400 mPas

(30) According to the assessment by the panelists, the organopolysiloxane gel obtained has very good distributability. The residue was classified as plentiful and by the majority as dry, silky and velvety.

Example 4 (Inventive, in a Two-Stage Process)

(31) The procedure corresponds to that of example 1, except that the hydrosilylation here is run in two stages. Firstly, the short-chain Si—H-containing polydimethylsiloxane is hydrosilylated on its own, then the long-chain Si—H-containing polydimethylsiloxane is hydrosilylated. The solvent used here, rather than the nonvolatile trimethylsilyl-terminated polydimethylsiloxane having a viscosity of 5 mPas from example 1, is decamethylcyclopentasiloxane. Moreover, in this example, there is no subsequent dilution, but addition of the total amount of diluent required from the start.

(32) A 2000 mL glass reaction vessel is equipped with a condenser with attached nitrogen inlet, heating mantle, anchor stirrer and closed-loop temperature controller. The reaction vessel is charged with 446.4 g of decamethylcyclopentasiloxane. Thereafter, 62.5 g of a 50% solution of an MQ resin (M/M.sup.vi/Q=7.6/1/11.4, M.sub.n=2570, M.sub.w=5440, iodine number=18), as described in example 1, in a nonvolatile linear trimethylsilyl-terminated polydimethylsiloxane having a viscosity of 5 mPas at 25° C. are added, followed by 46.8 g of short-chain Si—H-containing polydimethylsiloxane number 14 from table 1 (chain length 140). Lastly, 0.4 g of a mixture of platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in divinyltetramethyldisiloxane is added, with adjustment of the mixture such that the amount added corresponds to 51 ppm by weight of Pt, based on the sum total of the mass of the MQ resin and the two Si—H-containing polydimethylsiloxanes. Only the short-chain Si—H-containing polydimethylsiloxane was added here at first, but the amount of platinum is already calculated for the sum total of the amount of both Si—H-containing polydimethylsiloxanes. The reaction vessel is closed and purged with nitrogen for 5 min.

(33) Subsequently, the reaction mixture is heated to 95° C. at a stirrer speed of about 200 rpm, employing a heating rate of 45° C./h. Gel formation takes place within 30 minutes after the internal temperature of 95° C. has been attained. On completion of gel formation, stirring is continued at internal temperature 95° C. for one hour.

(34) Then 11.7 g of long-chain Si—H-containing polydimethylsiloxane number 28 from table 2 (chain length 450) are metered in and the mixture is stirred at 95° C. for a further hour. After this time, gel formation is complete.

(35) Thereafter, 3.24 g of polysiloxane having 3-mercaptopropyl groups and a viscosity of 190 mPas at 25° C. and a mercaptan content (SH content) of 0.29% by weight are added as stopper. The amount of mercaptan that was added in this way corresponds to 104 ppm by weight, based on the total amount of Si—H-containing polydimethylsiloxanes and MQ resin, and is thus twice as large as the amount of platinum used.

(36) The gel obtained has a solids content of 16% by weight and has a viscosity of 98,000 mPas at 25° C.

(37) According to the assessment by the panelists, the organopolysiloxane gel obtained has very good distributability. The residue was classified as plentiful and by the majority as silky and velvety.

Comparative Example 1

Noninventive, Solely Short-Chain Si—H-Containing Organopolysiloxane, High Heating Rate

(38) The procedure corresponds essentially to that described in example 1:

(39) By contrast with example 1, solely an Si—H-containing polydimethylsiloxane is used, which is short-chain Si—H-containing polydimethylsiloxane number 14 from table 1 (chain length 140, a:b=50:1). 102.4 g thereof are used.

(40) In this example, the heating rate is set to 90° C./h. Such a high heating rate is easy to achieve in the laboratory on this scale, but industrially at a size of 1 m.sup.3 or more is no longer possible, even when working with high-pressure steam. Moreover, there is the risk of significant local overheating that leads to drying-out of the gel at these sites and irreversible particle formation that destroys the sensory properties of the gel.

(41) A gel is obtained with a solids content of 16% by weight and a viscosity of 108,000 mPas at 25° C.

(42) According to the assessment by the panelists, the organopolysiloxane gel obtained has very good distributability. The residue was classified as plentiful and by the majority as predominantly silky and velvety.

Comparative Example 2

Noninventive, Analogous to Comparative Example 1, but with Lower Heating Rate

(43) The procedure corresponds to that of comparative example 1 except that heating is now at a heating rate of 45° C./h. The product does not attain the consistency of a gel, but remains free-flowing, and its properties correspond more to those of an oil. In an attempt to test it, it runs of its own accord even prior to manual distribution on the skin.

(44) By contrast with comparative example 1, what it leaves is not a matt, silky film but an oily, shiny layer, which has not been assessed as silky by any of the panelists.

(45) It is unsuitable for use in cosmetic products since it does not have a suitable consistency and does not have suitable sensory properties.

(46) The process in its composition according to comparative example 1, owing to its sensitivity to the heating rate, in the given composition, cannot be increased from the laboratory scale (with a high heating rate) to the production scale of 1 m.sup.3 or greater (with a lower heating rate).

Comparative Example 3

Noninventive, Analogous to Comparative Example 2 with Low Heating Rate but Longer-Chain Si—H-Containing Organopolysiloxane

(47) The procedure corresponds to that described in comparative example 2, except that the Si—H-containing organopolysiloxane used is long-chain Si—H-containing polydimethylsiloxane number 28 from table 2 (chain length 450, a:b=50:1) rather than the short-chain Si—H-containing organopolysiloxane. Only this one Si—H-containing polydimethylsiloxane is used.

(48) An elastomer gel is obtained which, at a solids content of 16% by weight, has a viscosity of 205,000 mPas at 25° C. and which, at a solids content of 14% by weight, has a viscosity of 122,000 mPas at 25° C.

(49) By contrast with comparative example 1, a very much higher viscosity is obtained at a desired solids content of 16% by weight. If the solids content is reduced to 14% by weight, only then is a comparable viscosity to that in comparative example 1 obtained. But both factors, the solids content and the viscosity, affect the sensory properties of the gel.

(50) According to the assessment of the gel adjusted to 122 000 mPas by the panelists, the organopolysiloxane gel obtained has very good distributability. The residue was classified as plentiful and as silky and oily.

(51) The gel obtained is suitable for production of cosmetic products, but has good sensory distinguishability from the corresponding gel from comparative example 1. In the direct comparison, 4 out of 5 panelists preferred the gel from comparative example 1 over this gel.

(52) The test was then repeated with the same panelists, without telling them that they were comparing the same gels with one another again. In the repetition, 5 out of 5 panelists preferred the gel from comparative example 1 over this gel.

(53) In the transfer from the laboratory scale with high heating rate to the production scale with low heating rate, on replacement of the short-chain Si—H-containing organopolysiloxane by the long-chain Si—H-containing organopolysiloxane, it is not possible to obtain an organopolysiloxane gel having comparable sensory properties.

Example 5

Inventive, Adjustment of the Amounts of Si—H-Containing Organopolysiloxanes to Altered Heating Rate, with Retention of the Same Properties of the Organopolysiloxane Gel

(54) The procedure corresponds to that described in example 1. By contrast with example 1, however, heating is now not at 45° C./h, but at 90° C./h, i.e. twice as high a heating rate is employed.

(55) By contrast with example 1, the following amounts of the Si—H-containing polydimethylsiloxanes are now used:

(56) 92 g of Si—H-containing polydimethylsiloxane number 14 from table 1 (chain length 140) and 10 g of Si—H-containing polydimethylsiloxane number 28 from table 2 (chain length 450, a:b=50:1).

(57) Otherwise, the experimental procedure corresponds exactly to that described in example 1. As a result, an organopolysiloxane gel having a viscosity of 121,000 mPas is obtained at a solids content of 16% by weight.

(58) According to the assessment by the panelists, the organopolysiloxane gel obtained has very good distributability. The residue was classified as plentiful and by the majority as predominantly silky and velvety.

(59) In the direct comparison test, 3 out of 5 panelists preferred the gel from example 1 over this gel from example 5. The comparison test was repeated with the same panelists, without telling them that they were comparing the same gels with one another again. In the repetition, 2 out of 5 panelists preferred the gel from example 1 over this gel from example 5, and only one of the two panelists who preferred the gel from example 1 in the repeat test already arrived at this result in the first test. There is therefore no certain distinguishability of the two gels from example 1 and from example 5 on the basis of their sensory properties.

(60) This means that the two gels have virtually equivalent properties and the inventive use of two kinds of Si—H-containing organopolysiloxanes, a short-chain and a long-chain Si—H-containing organopolysiloxane, permits adjustment to altered boundary conditions, such as change in the heating rate, with retention of the desired properties of the organopolysiloxane gel, which would not be possible with use of just one kind of Si—H-containing organopolysiloxane, solely a short-chain or solely a long-chain Si—H-containing organopolysiloxane.