Skin-adhesive silicone gel

Abstract

Silicone gels are described that are adhesive to the skin. The gels are able to be used in particular for articles that are adhesive to the skin for medical or paramedical use.

Claims

1. A silicone composition A which is a precursor of a silicone gel G and which is crosslinkable by hydrosilylation, the silicone composition A comprising: 1) at least one organopolysiloxane B comprising: (I) at least two siloxyl units of formula (B1):
(Y).sub.a(Z).sub.bSiO.sub.(4(a+b)/2(B1) in which: Y represents a monovalent radical containing from 2 to 6 carbon atoms, having at least one alkenyl group, Z represents a monovalent radical containing from 1 to 20 carbon atoms and not comprising an alkenyl group; a and b represent integers, a being 1, 2 or 3, b being 0, 1 or 2 and (a+b) being 1, 2 or 3; (ii) and optionally comprising other siloxyl units of formula (B2):
(Z).sub.cSiO.sub.(4c)/2(B2) Z has the same meaning as above, and c represents an integer which is 0, 1, 2 or 3, 2) at least one organopolysiloxane CE comprising: two siloxyl end units, which are identical or different, of formula (CE-1):
(H).sub.p(R.sup.1).sub.qSiO.sub.1/2(CE-1) in which: the symbol R.sup.1 corresponds to a C.sub.1 to C.sub.8 alkyl group or to a C.sub.6 to C.sub.10 aryl group; and the symbol H represents a hydrogen atom, with p=0 or 1, q=2 or 3 and (p+q)=3; at least one siloxyl unit of formula (CE-2):
(H).sub.n(R.sup.2).sub.mSiO.sub.2/2(CE-2) in which the radical R.sup.2 corresponds to a C.sub.1 to C.sub.8 alkyl group or a C.sub.6 to C.sub.10 aryl group, the symbol H represents a hydrogen atom and with n=0 or 1, m =1 or 2 and (n+m)=2, and wherein the organopolysiloxane CE contains two hydrogen atoms each one bonded to a different silicon atom per polymer, 3) at least one organopolysiloxane XL comprising: at least three siloxy units of formula (XL-1):
(H)(L).sub.eSiO.sub.(3e)/2(XL-1) in which the symbol H represents a hydrogen atom, the symbol L represents an alkyl having from 1 to 8 carbon atoms inclusive or a C.sub.6 to C.sub.10 aryl, and the symbol e is equal to 0, 1 or 2; and optionally other siloxy units of formula (XL-2):
(L).sub.gSiO.sub.(4g)/2(XL-2) in which the symbol L represents an alkyl having from 1 to 8 carbon atoms inclusive or a C.sub.6 to C.sub.10 aryl and the symbol g is equal to 0, 1, 2 or 3, and wherein the organopolysiloxane XL contains from 2.5% to 15.0% by weight of SiH function per polymer, 4) an effective amount of at least one hydrosilylation catalyst E, 5) at least one hydrosilylation reaction inhibitor D, 6) optionally at least one additive K, and the weight amounts of the organopolysiloxanes B, CE and XL are chosen so as to satisfy the following three conditions: a) a molar ratio RHAlk=tH/tAlk3.0, b) a molar ratio RH.sup.CEV=nH.sup.CE/tAlk2.25; and c) a mol % RH.sup.CE=(nH.sup.CE/tH)100, which is greater than or equal to the value RH.sup.CE1, which is determined by the formula: RH.sup.CE1=81.36(3.6RHAlk), wherein: tH=number of moles of hydrogen atom directly bonded to a silicon atom of the organopolysiloxanes CE and XL, tAlk=number of moles of alkenyl directly bonded to a silicon atom of the organopolysiloxane B; and nH.sup.CE=number of moles of hydrogen atom directly bonded to a silicon atom of the organopolysiloxane CE.

2. The silicone composition A as claimed in claim 1, wherein: the organopolysiloxane B has a dynamic viscosity at 25 C. of from 100 mPa.Math.s to 120,000 mPa.Math.s, the organopolysiloxane CE has a dynamic viscosity at 25 C. of from 1 mPa.Math.s to 500 mPa.Math.s, and the organopolysiloxane XL has a dynamic viscosity at 25 C. of from 5 mPa.Math.s to 2,000 mPa.Math.s.

3. The silicone composition A as claimed in claim 2, wherein the organopolysiloxanes B, CE and XL are chosen such that a dynamic viscosity at 25 C. of the silicone composition A is from 200 mPa.Math.s to 100,000 mPa.Math.s.

4. The silicone composition A as claimed in claim 1, wherein: the organopolysiloxane CE has at least 5 silicon atoms and a (number of moles of SiH group)/(total number of silicon atoms) ratio of from 0.05 to 0.40, and the organopolysiloxane XL has at least 5 silicon atoms and a (number of moles of SiH group)/(total number of silicon atoms) ratio of from 0.05 to 0.80.

5. The silicone composition A as claimed in claim 1, wherein the composition comprises at least two organopolysiloxanes B comprising, per molecule, at least two C.sub.2 to C.sub.6 alkenyl radicals each bonded to a silicon atom, the first of the at least two C.sub.2 to C.sub.6 alkenyl radicals having a dynamic viscosity at 25 C. of from 50,000 mPa.Math.s and 120,000 mPa.Math.s, and the second of the at least two C.sub.2 to C.sub.6 alkenyl radicals having a dynamic viscosity at 25 C. of from 500 mPa.Math.s to 20,000 mPa.Math.s.

6. A silicone gel G, wherein the silicone gel G is obtained by crosslinking the composition A as claimed in claim 1, by heating at a temperature of from 70 C. to 200 C. and/or under the action of infrared radiation.

7. The silicone gel G as claimed in claim 6, wherein the gel is included in a medical device selected from the group consisting of a mammary prosthesis, an adhesive dressing which adheres to the skin and a sensor-, probe-, catheter- or needle-type device for holding in place medical accessories used in contact with the skin.

8. An item which adheres to the skin, the item comprising a substrate S, which is a plastic film, wherein at least one of two surfaces of the substrate S is continuously or discontinuously coated with the silicone gel G as claimed in claim 6.

9. The item as claimed in claim 8, wherein the substrate S is a perforated flexible polyurethane film or a continuous flexible polyurethane film.

10. A dressing or patch for medical or paramedical use, the dressing or patch comprising the item which adheres to the skin as claimed in claim 8.

11. A mammary prosthesis comprising a polyurethane pouch comprising the silicone gel G as claimed in claim 6.

12. A cushion or mattress for minimizing pressure sores, the cushion or mattress comprising the silicone gel G as claimed in claim 6.

13. The silicone composition A as claimed in claim 1, wherein the organopolysiloxane CE contains, per polymer, two siloxyl units of formula (CE-1) in which p=1 and at least one siloxyl unit of formula (CE-2) in which n=0.

14. The silicone composition A as claimed in claim 1, wherein organopolysiloxane XL contains from 3.0% to 15.0% by weight of SiH function per polymer.

15. The silicone composition A as claimed in claim 14, wherein the organopolysiloxane XL contains from 3.5% to 12.5% by weight of SiH function per polymer.

16. The silicone composition A as claimed in claim 1, wherein the molar ratio RHAlk satisfies the relation: 3.0RHAlk=tH/tAlk24.

17. The silicone composition A as claimed in claim 16, wherein the molar ratio RHAlk satisfies the relation: 3.5RHAlk20.

18. The silicone composition A as claimed in claim 1, wherein the molar ratio RH.sup.CEV satisfies the relation: 2.25RH.sup.CEV=nH.sup.CE/tAlk24.

19. The silicone composition A as claimed in claim 18, wherein the molar ratio RH.sup.CEV satisfies the relation: 2.25RH.sup.CEV10.

20. The silicone composition A as claimed in claim 2, wherein the dynamic viscosity at 25 C. of the polyorganosilicone CE is from 5 to 200 mPa.Math.s.

21. The silicone composition A as claimed in claim 2, wherein the dynamic viscosity at 25 C. of the polyorganosilicone CE is from 5 to 500 mPa.Math.s.

22. The silicone composition A as claimed in claim 3, wherein the organopolysilanes B, CE and XL are chosen such that the dynamic viscosity at 25 C. of the silicone composition A is from 200 mPa.Math.s, to 80,000 mPa.Math.s.

23. The silicone composition A as claimed in claim 4, wherein the (number of moles of SiH group)/(total number of silicon atoms) ratio of the organopolysiloxane CE is from 0.08 to 0.35.

24. The silicone composition A as claimed in claim 4, wherein the (number of moles of SiH group)/(total number of silicon atoms) ratio of the organopolysiloxane XL is from 0.05 to 0.50.

Description

EXAMPLES

(1) 1) Measurement of the Tack:

(2) The test is carried out according to the standard ASTM D2979 with a PROBE TACK device (PT-1000). A cylindrical punch with a flat face is brought into contact with the gel of the composite to be tested (surface area of contact with the gel=0.2 cm.sup.2). The composite consists of a (paper-supported) flexible polyurethane film coated with 200 g/m.sup.2 of the silicone composition which is a precursor of the gel. The punch is then kept in contact with the gel for a contact time of 1 second at a constant pressure of 100 gf/cm.sup.2. Next, the punch is detached from the gel at a constant speed of 10 mm/s, and the detachment energy required to separate the gel from the rod is measured and expressed in mJ/cm.sup.2.

(3) 2) Evaluation of the Adhesion (Rub-Off) of the Silicone Gel to the Support which is a Flexible Polyurethane Film and of the Quality of the Gel

(4) The adhesion of the silicone gel to the support which is a flexible polyurethane film or Rub-Off) measurement consists of a qualitative evaluation of the resistance of the gel during scrubbing with the finger. The surface of the gel is rubbed with the finger and the number of (forward-and-back) passes of the finger is counted until a delamination appears. The gel will be considered to be more adhesive to the polyurethane film if the number of passes of the finger is higher before observing the delamination of the gel from its substrate. Above 30 scrubbings forward-and-back with the finger, it is considered that the adhesion to the polyurethane support is satisfactory.

(5) The quality of the gel is evaluated by means of a penetrometer (PEN) according to the standard NF ISO 2137, using a Petrotest penetrometer, model PNR 12, with a total weight of the rod and cone fixed at 62.5 g. The cone penetrability of a silicone gel is determined at 25 C. by measuring the depth of penetration of the cone into the sample, said depth being obtained by releasing the cone assembly of the penetrometer and leaving the cone to act for 5 seconds. The results are expressed in tenths of a mm (mm/10).

(6) 3) Preparation of the Gel Precursor Silicone Compositions According to the Invention

(7) a) Starting Materials Used POS B1=,-(dimethylvinylsiloxy) polydimethylsiloxane oil having a dynamic viscosity at 25 C. equal to 60 000 mPa.Math.s. POS B2=,-(dimethylvinylsiloxy) polydimethylsiloxane oil having a dynamic viscosity at 25 C. equal to 10 000 mPa.Math.s. POS B3=,-(dimethylvinylsiloxy) polydimethylsiloxane oil having a dynamic viscosity at 25 C. equal to 1000 mPa.Math.s. POS CE=poly(dimethylsiloxy)-, dimethylhydrosiloxy oil having a viscosity of approximately 8.5 mPa.Math.s, containing on average 5.7% by weight of SiH unit, having a structure of the M.sup.HD.sub.xM.sup.H type with x between on average 7 and 15 and having a (number of SiH groups)/(total number of silicon atoms) ratio=0.154; POS XL.sup.1=poly(dimethylsiloxy) (methylhydrosiloxy) , dimethylhydrosiloxy oil having an average viscosity of 395 mPa.Math.s, containing 1.90% by weight of SiH groups (or 0.066% by weight of hydrogen atom originating from SiH functions) per polymer and having a structure of the M.sup.HD.sub.xD.sub.w.sup.HM.sup.H type with x between on average 73 and 77 and w on average between 1 and 3 and having a (number of SiH groups)/(total number of silicon atoms) ratio=0.048; POS XL.sup.2=poly(dimethylsiloxy) (methylhydrosiloxy) , dimethylhydrosiloxy oil having an average viscosity of 275 mPa.Math.s, containing 4.75% by weight of SiH groups (or 0.165% by weight of hydrogen atom originating from SiH functions) per polymer and having a structure of the M.sup.HD.sub.xD.sub.w.sup.HM.sup.H type with x between on average 132 and 136 and w on average between 15 and 17 and having a (number of SiH groups)/(total number of silicon atoms) ratio=0.116; POS XL.sup.3=poly(dimethylsiloxy) (methylhydrosiloxy) , dimethylhydrosiloxy oil having an average viscosity of 30 mPa.Math.s, containing 7.30% by weight of SiH groups (or 0.253% by weight of hydrogen atom originating from SiH functions) per polymer and having a structure of the M.sup.HD.sub.xD.sub.w.sup.HM.sup.H type with x between on average 24 and 28 and w on average between 3 and 5 and having a (number of SiH groups)/(total number of silicon atoms) ratio=0.181; POS XL.sup.4=poly(dimethylsiloxy) (methylhydrosiloxy) , dimethylhydrosiloxy oil having an average viscosity of 22 mPa.Math.s, containing 20.00% by weight of SiH groups (or 0.694% by weight of hydrogen atom originating from SiH functions) per polymer and having a structure of the M.sup.HD.sub.xD.sub.w.sup.HM.sup.H type with x between on average 18 and 20 and w on average between 15 and 17 and having a (number of SiH groups)/(total number of silicon atoms) ratio=0.478; POS XL.sup.5: poly(dimethylsiloxy) (methylhydrosiloxy) , dimethylhydrosiloxy oil having an average viscosity of 40 mPa.Math.s, containing 30.50% by weight of SiH groups (or 1.059% by weight of hydrogen atom originating from SiH functions) per polymer and having a structure of the M.sup.HD.sub.xD.sub.w.sup.HM.sup.H type with x between on average 17 and 19 and w on average between 36 and 38 and having a (number of SiH groups)/(total number of silicon atoms) ratio=0.655; Hydrosilylation catalyst E (Cate E)=organometallic platinum complex (Karstedt Platinum) used as hydrosilylation reaction catalyst corresponding to 10% of platinum. Inhibitor D=hydrosilylation reaction inhibitor=1-ethynyl-1-cyclohexanol (ECH)
b) Preparation of the Composites (=Support Coated with a Silicone Gel)

(8) The silicone compositions tested are in the two-component form. The parts called Part A and Part B are then mixed in a 1:1 weight ratio. The composition before crosslinking is indicated in the table corresponding to the test. The silicone composition which is a precursor of a gel is then applied, at a content of 200 g/m.sup.2, to a polyurethane support (paper-supported flexible film) using a coating scraper. After the coating, the crosslinking of the composite is carried out for 30 min at 120 C. in a ventilated oven so as to obtain a support coated with a gel. The results are reported in tables 1 to 8 below.

(9) In these tables, the symbol x signifies that the measurement was not carried out since a hard silicone elastomer was obtained, that is to say different than a silicone gel.

(10) TABLE-US-00001 TABLE 1 Properties of the gels obtained from a composition comprising a POS XL.sup.1 crosslinker containing 1.90% by weight of SiH groups per polymer. Test No. C-1 C-2 C-3 C-4 C-5 C-6 C-7 C-8 Parts by weight (per 100 parts of the composition) POS B1 85.53 87.53 81.57 82.51 79.58 81.76 81.53 75.53 POS B3 4.4508 4.4508 4.12 4.27 4.01 4.23 4.45 4.45 ECH 0.0060 0.0060 0.0051 0.0055 0.0048 0.0054 0.0060 0.0060 POS CE 0.00 3.00 2.55 4.00 2.40 5.00 9.00 15.01 POS XL.sup.1 10.00 5.00 11.75 9.20 14.00 9.00 5.00 5.00 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 Calculations ratios of the silicone compositions which are precursors of a gel RHAlk 2.2 2.9 4.4 4.7 5.0 5.3 6.9 11.5 RH.sup.CEV 0.00 1.80 1.64 2.54 1.59 3.21 5.75 10.24 RH.sup.CE 0.00 62.19 37.31 54.37 31.97 60.35 83.15 89.16 RH.sup.CE1 = 81.36 (3.6 RHAlk) 73.31 70.93 65.49 64.53 63.49 62.23 56.47 40.02 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 100.00 12.33 43.04 15.75 49.64 3.02 +47.26 +122.80 Properties of the gels obtained after crosslinking Physical state = gel No No No No No No No No Gel adhesive to No No No No No No No No polyurethane support and having a good tack (14 mJ/cm.sup.2)
When a crosslinker having 1.90% by weight of SiH functions is used, even in SiH excess within the composition (RHAlk between 2 and 11), a silicone gel is not obtained.

(11) TABLE-US-00002 TABLE 2 Properties of the gels obtained from a composition comprising a POS XL.sup.2 crosslinker containing 4.75% by weight of SiH groups per polymer and a POS B2 having a viscosity of 10 000 mPa .Math. s at 25 C. Test No. C-9 C-10 C-11 C-12 I-13 I-14 I-15 Parts by weight (per 100 parts of the composition) POS B2 94.80 93.33 92.26 92.32 92.34 92.38 92.39 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 POS XL.sup.2 0.93 1.29 2.77 2.16 1.92 1.56 1.39 POS CE 4.26 5.36 4.95 5.51 5.72 6.05 6.20 ECH 0.0080 0.0080 0.0080 0.0080 0.0080 0.0080 0.0080 Calculations ratios of the silicone compositions which are precursors of a gel RHAlk 2.000 2.600 3.000 3.000 3.000 3.000 3.000 RH.sup.CEV 1.675 2.140 2.000 2.222 2.308 2.439 2.500 RH.sup.CE 83.75 82.30 66.67 74.07 76.92 81.30 83.33 RH.sup.CE1 = 81.36 (3.6 RHAlk) 74.16 72.00 70.56 70.56 70.56 70.56 70.56 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 +12.94 +14.31 5.52 +4.98 +9.02 +15.22 +18.10 Properties of the gels obtained after crosslinking Physical state = gel Yes Yes Yes Yes Yes Yes Yes Penetrometer (mm/10) 178 210 110 175 210 265 277 Tack (mJ/cm.sup.2) 12 12 12 13 17 18 17 Rub-off number of passes 42 >50 >50 >50 >50 >50 >50 Gel adhesive to No No No No Yes Yes Yes polyurethane support and having a good tack (14 mJ/cm.sup.2)

(12) TABLE-US-00003 TABLE 3 Properties of the gels obtained from a composition comprising a POS XL.sup.2 crosslinker containing 4.75% by weight of SiH groups per polymer and a POS B2 having a viscosity of 10 000 mPa .Math. s at 25 C. Test No. I-16 I-17 I-18 I-19 I-20 POS B2 79.60 79.70 79.79 70.77 70.88 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 POS XL.sup.2 10.77 9.59 8.51 20.20 18.68 POS CE 9.62 10.70 11.69 9.02 10.42 ECH 0.0080 0.0080 0.0080 0.0080 0.0080 Ratio calculations RHAIk 9.000 9.000 9.000 14.239 14.239 RH.sup.CEV 4.500 5.000 5.454 4.746 5.477 RH.sup.CE 50.00 55.56 60.61 33.33 38.46 RH.sup.CE1 = 81.36 (3.6 RHAIk) 48.96 48.96 48.96 30.10 30.10 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 +2.12 +13.47 +23.78 +10.74 +27.78 Properties of the gels obtained after crosslinking Physical state = gel Yes Yes Yes Yes Yes Penetrometer (mm/10) 174 213 235 196 220 Tack (mJ/cm.sup.2) 17 19 19 18 20 Rub-off number of passes >50 >50 >50 >50 >50 Gel adhesive to polyurethane Yes Yes Yes Yes Yes support and having a good tack (14 mJ/cm.sup.2)

(13) TABLE-US-00004 TABLE 4 Properties of the gels obtained from a composition comprising a POS XL.sup.2 crosslinker containing 4.75% by weight of SiH groups per polymer and a POS B1 having a viscosity of 60 000 mPa .Math. s at 25 C. Test No. C-21 C-22 C-23 C-24 C-25 C-26 I-27 I-28 Parts by weight (per 100 parts of the composition) POS B1 93.54 90.54 92.91 90.54 86.53 86.85 87.08 83.55 POS B3 4.45 4.45 4.44 4.45 4.45 4.45 4.44 4.45 ECH 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 POS CE 0.00 0.00 1.99 2.50 4.00 5.10 6.58 7.00 POS XL.sup.2 2.00 5.00 0.65 2.50 5.00 3.60 1.89 5.00 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 Ratio calculations RHAlk 1.0 2.6 1.5 2.8 5.1 5.0 5.0 7.2 RH.sup.CEV 0.00 0.00 1.14 1.46 2.44 3.10 3.99 4.40 RH.sup.CE 0.00 0.00 77.59 52.94 47.37 61.45 79.62 61.17 RH.sup.CE1 = 81.36 (3.6 RHAlk) 77.72 71.99 76.06 71.41 62.83 63.22 63.34 55.49 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 100.00 100.00 +2.00 25.86 24.61 2.80 +25.72 +10.23 Properties of the gels obtained after crosslinking Physical state = gel No No No No No Yes Yes Yes Penetrometer (mm/10) x x x x 64 103 233 128 Tack (mJ/cm.sup.2) x x x x x 12 19 14 Rub-off number of passes x x x x x >50 >50 >50 Gel adhesive to No No No No No No Yes Yes polyurethane support and having a good tack (14 mJ/cm.sup.2)

(14) TABLE-US-00005 TABLE 5 Properties of the gels obtained from a composition comprising a POS XL.sup.2 crosslinker containing 4.75% by weight of SiH groups per polymer and a POS B1 having a viscosity of 60 000 mPa .Math. s at 25 C. Test No. I-29 I-30 I-31 I-32 I-33 I-34 I-35 Parts by weight (per 100 parts of the composition) POS B1 83.40 83.55 84.05 83.95 78.05 73.05 73.05 POS B3 4.45 4.45 4.45 4.45 4.45 4.45 4.45 ECH 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 POS CE 7.65 8.00 8.49 8.99 9.99 9.99 12.49 POS XL.sup.2 4.50 4.00 3.00 2.60 7.50 12.49 9.99 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 Ratio calculations RHAlk 7.3 7.3 7.0 7.1 11.1 14.9 15.1 RH.sup.CEV 4.81 5.02 5.31 5.63 6.66 7.05 8.81 RH.sup.CE 65.67 69.23 76.12 79.57 60.00 47.37 58.44 RH.sup.CE1 = 81.36 (3.6 RHAlk) 54.99 55.24 56.25 55.90 41.41 27.81 27.11 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 +19.42 +25.33 +35.33 +42.35 +44.90 +70.32 +115.59 Properties of the gels obtained after crosslinking Physical state = gel Yes Yes Yes Yes Yes Yes Yes Penetrometer (mm/10) 152 178 209 251 173 181 227 Rub-off number of passes >50 >50 >50 >50 >50 >50 >50 Tack (mJ/cm.sup.2) 16 20 20 20 17 20 20 Gel adhesive to Yes Yes Yes Yes Yes Yes Yes polyurethane support and having a good tack (14 mJ/cm.sup.2)

(15) TABLE-US-00006 TABLE 6 Properties of the gels obtained from a composition comprising a POS XL.sup.3 crosslinker containing 7.3% by weight of SiH groups per polymer and a POS B1 having a viscosity of 60 000 mPa .Math. s at 25 C. Test No. I-36 I-37 I-38 I-39 I-40 I-41 Parts by weight (per 100 parts of the composition) POS B1 90.79 90.76 87.78 87.53 85.38 85.08 POS B3 4.4508 4.4747 4.4508 4.4508 4.4508 4.4508 ECH 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 POS CE 4.00 3.65 6.25 7.00 7.65 8.58 POS XL.sup.3 0.75 1.10 1.50 1.00 2.50 1.88 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 Ratio calculations RHAlk 2.9 3.0 5.0 5.1 6.9 6.9 RH.sup.CEV 2.33 2.12 3.74 4.20 4.69 5.28 RH.sup.CE 78.90 69.94 74.50 83.08 68.21 76.23 RH.sup.CE1 = 81.36 (3.6 RHAlk) 70.75 70.45 63.27 63.15 56.58 56.43 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 +11.53 0.71 +17.75 +31.56 +20.55 +35.08 Properties of the gels obtained after crosslinking Physical state = gel Yes Yes Yes Yes Yes Yes Penetrometer (mm/10) 224 146 231 286 227 Rub-off number of passes >50 >50 >50 >50 >50 >50 Tack (mJ/cm.sup.2) 11 11 17 20 22 17 Gel adhesive to No No Yes Yes Yes Yes polyurethane support and having a good tack (14 mJ/cm.sup.2)

(16) TABLE-US-00007 TABLE 7 Properties of the gels obtained from a composition comprising a POS XL.sup.4 crosslinker containing 20.0% by weight of SiH groups per polymer and a POS B1 having a viscosity of 60 000 mPa .Math. s at 25 C. Test No. C-42 C-43 C-44 C-45 C-46 Parts by weight (per 100 parts of the composition) POS B1 93.04 92.54 90.26 89.56 88.08 POS B3 4.45 4.45 4.47 4.47 4.45 ECH 0.0060 0.0060 0.0060 0.0060 0.0060 POS CE 2.00 2.00 5.00 4.95 7.00 POS XL.sup.4 0.50 1.00 0.25 1.00 0.45 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 Ratio calculations RHAIk 2.3 3.5 3.5 5.3 5.3 RH.sup.CEV 1.15 1.16 2.95 2.94 4.22 RH.sup.CE 50.12 33.44 83.40 55.42 79.62 RH.sup.CE1 = 81.36 (3.6 RHAIk) 73.10 68.92 68.63 62.27 62.27 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 31.44 51.48 +21.51 11.00 +27.86 Properties of the gels obtained after crosslinking Physical state = gel No No Yes No No Penetrometer (mm/10) x x 124 23 63 Rub-off number of passes x x >50 x x Tack (mJ/cm.sup.2) x x 11 x x Gel adhesive to polyurethane No No No No No support and having a good tack (14 mJ/cm.sup.2)

(17) TABLE-US-00008 TABLE 8 Properties of the gels obtained from a composition comprising a POS XL.sup.5 crosslinker containing 30.50% by weight of SiH groups per polymer and a POS B1 having a viscosity of 60 000 mPa .Math. s at 25 C. Test No. C-47 C-48 C-49 C-50 C-51 C-52 C-53 Parts by weight (per 100 parts of the composition) POS B1 91.14 91.54 90.69 88.29 87.54 85.29 81.29 POS B3 4.4486 4.4504 4.4508 4.4504 4.4504 4.4504 4.4504 ECH 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 0.0060 POS CE 4.25 3.75 4.75 7.00 7.50 10.00 14.00 POS XL.sup.5 0.15 0.25 0.10 0.25 0.50 0.25 0.25 Pt Catalyst 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 Ratio calculations RHAlk 2.9 3.0 3.1 5.0 6.2 7.0 9.9 RH.sup.CEV 2.46 2.16 2.76 4.17 4.50 6.14 8.96 RH.sup.CE 83.61 72.97 89.53 83.44 72.97 87.80 90.97 RH.sup.CE1 = 81.36 (3.6 RHAlk) 70.77 70.69 70.24 63.37 59.15 56.19 45.89 [(RH.sup.CE RH.sup.CE1)/RH.sup.CE1] *100 +18.15 +3.24 +27.46 +31.68 +23.36 +56.28 +98.25 Properties of the gels obtained after crosslinking Physical state = gel Yes No Yes No No No Yes Penetrometer (mm/10) 139 64 224 x x x 99 Rub-off number of passes >50 x >50 x x x 25 Tack (mJ/cm.sup.2) 13 x 13 x x x 12 Gel adhesive to No No No No No No No polyurethane support and having a good tack (14 mJ/cm.sup.2)