ELASTOMERIC COMPOSITIONS AND THEIR APPLICATIONS

Abstract

A gel is provided which is the condensation reaction product of the following composition: (i) at least one condensation curable silyl terminated polymer having at least one hydrolysable and/or hydroxyl functional group(s) per molecule; (ii) a cross-linker selected from the group of a silicone, an organic polymer, a silane or a disilane molecule which contains at least two hydrolysable groups per molecule; and (iii) a condensation catalyst selected from the group of titanates, zirconates or tin (II). The molar ratio of hydroxyl and/or hydrolysable groups in polymer (i) to hydrolysable groups from component (ii) is between 0.5:1 and 1:1 using a monosilane cross-linker or 0.75:1 to 3:1 using disilanes, and the molar ratio of M-OR or tin (II) functions to the hydroxyl and/or hydrolysable group(s) in polymer (i) is comprised between 0.01:1 and 0.5:1, where M is titanium or zirconium. The composition, and uses for the gel are also disclosed.

Claims

1. A gel which is the condensation reaction product of the following composition: (i) at least one condensation curable silyl terminated polymer having at least one hydrolysable and/or hydroxyl functional group(s) per molecule; (ii) a cross-linker selected from the group of a silicone, an organic polymer, a silane or a disilane molecule which contains at least two hydrolysable groups per molecule; and (iii) a condensation catalyst selected from the group of titanates, zirconates or tin (II); wherein the molar ratio of hydroxyl and/or hydrolysable group(s) in polymer (i) to hydrolysable groups from component (ii) is between 0.5:1 and 1:1 using a monosilane cross-linker or 0.75:1 to 3:1 using disilanes; and wherein the molar ratio of M-OR or tin (II) functions to the hydroxyl and/or hydrolysable group(s) in polymer (i) is comprised between 0.01:1 and 0.5:1, where M is titanium or zirconium.

2. A condensation curable gel composition for making the gel in accordance with claim 1, the composition comprising components (i), (ii), and (iii).

3. The condensation curable gel composition in accordance with claim 2, wherein the composition is stored in two parts having polymer (i) and cross-linker (ii) in one part, and polymer (i) and catalyst (iii) in the other part.

4. The condensation curable gel composition in accordance with claim 2, wherein the composition is stored in two parts having cross-linker (ii) in one part, and polymer (i) and catalyst (iii) in the other part.

5. The condensation curable gel composition in accordance with claim 2, wherein the composition is stored in two parts having a first polymer (i) and cross-linker (ii) in one part, and a second polymer (i) and catalyst (iii) in the other part.

6. The condensation curable gel composition in accordance with claim 2, wherein the molar ratio of hydroxyl and/or hydrolysable group(s) in polymer (i) to hydrolysable groups from component (ii) is between 0.5:1 and 0.75:1 using a monosilane cross-linker or 0.75:1 to 3:1 using disilanes.

7. The condensation curable gel composition in accordance with claim 2, wherein the molar ratio of M-OR or tin (II) functions to the hydroxyl and/or hydrolysable group(s) in polymer (i) is comprised between 0.02:1 and 0.2:1.

8. The condensation curable gel composition in accordance with claim 2, further comprising a polymer curable by hydrosilylation, a hydrosilylation cross-linker, and a hydrosilylation catalyst.

9. The gel in accordance with claim 1, exhibiting a hardness below Shore 80 in the type 00 scale according to ASTM D 2240-05(2010).

10. A method of making the gel in accordance with claim 1, wherein the composition is stored in two parts, provided the cross-linker (ii) is in one part, the catalyst (iii) is in the other part, and the polymer (i) is in either or both parts, and wherein the two parts of the composition are intermixed and cured.

11. An encapsulant or a pottant for electronic devices, solar photovoltaic modules, and/or light emitting diodes, wherein the encapsulant or pottant comprises the gel according to claim 1.

12. An implant, a shoe sole, or a self-sealing anti-puncture coating for tyres, wherein the implant, shoe sole, or coating comprises the gel in accordance with claim 1.

13. A pressure sensitive adhesive comprising the gel in accordance with claim 1.

14. A lamination process to laminate substrates together comprising laminating at least one substrate to another substrate with the gel in accordance with claim 1.

15. A coating formed from the condensation curable gel composition in accordance with claim 2, wherein the composition is applied on to a substrate using a dispenser selected from curtain coaters, spray devices, die coaters, dip coaters, extrusion coaters, knife coaters, and screen coaters.

16. A medical application comprising the gel in accordance with claim 1.

17. The medical application in accordance with claim 16, wherein the gel is for drug delivery, the gel is for wound care, a soft skin adhesive comprises the gel, a transdermal patch comprises the gel, and/or the gel is for the controlled release of medicaments.

18. The gel in accordance with claim 1, which is also the hydrosilylation reaction product of: a polymer curable by hydrosilylation; a hydrosilylation cross-linker; and a hydrosilylation catalyst.

19. The gel in accordance with claim 1, wherein the polymer (i) of the composition has at least two hydrolysable and/or hydroxyl functional groups per molecule.

20. The gel in accordance with claim 1, wherein the cross-linker (ii) of the composition contains at least three hydrolysable groups per molecule.

Description

EXAMPLES

[0062] In a first embodiment wherein the gel is solely cured via a condensation pathway, a series of gels (examples 1 to 16) as herein described were prepared as a one part composition (to save lab time). It was identified that compositions of the type depicted in Examples 1-16 will in practice have to be sold in multiple part compositions because they were found to cure in the cartridge prior to intended use. Examples 17-19 provide examples of how the compositions need to be stored prior to use with a view to avoid curing in storage. The compositions in Examples 1 to 19 were unexpectedly found to be cured in bulk after only 2 to 3 hours, contrary to expectations. All viscosity values were measured at 23° C. using a Brookfield cone plate viscometer (RV DIII) adapting the cone plate and the speed according to the polymer viscosity. Each prepared composition was evaluated to determine penetration and softness, using the methods described below, in the Tables below:

Example 1

[0063] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 1 part by weight of methyltrimethoxysilane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.08 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 70 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in a Relative Humidity (RH) of 50%.

Example 2

[0064] The same method of preparation was utilised as described in Example 1 with the exception that 1 part of tetraethoxysilane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 3

[0065] The same method of preparation was utilised as described in Example 1 with the exception that 0.4 parts of 1, 6-bis(trimethoxysilyl)hexane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 4

[0066] The same method of preparation was utilised as described in Example 1 with the exception that 0.5 parts of 1, 6-bis(trimethoxysilyl)hexane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 5

[0067] The same method of preparation was utilised as described in Example 1 with the exception that 0.7 parts of 1, 6-bis(trimethoxysilyl)hexane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 6

[0068] The same method of preparation was utilised as described in Example 1 with the exception that 1 part of 1, 6-bis(trimethoxysilyl)hexane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 7

[0069] The same method of preparation was utilised as described in Example 1 with the exception that 1 part of methyltrioximino silane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 8

[0070] The same method of preparation was utilised as described in Example 1 with the exception that 1 part of a 50/50 by weight mixture of methyl triacetoxysilane and ethyl triacetoxysilane per 100 parts by weight of the polymer was utilised as the cross-linker.

Example 9

[0071] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethyl siloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.8 part of methyltrimethoxysilane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.02 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 184.69 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 10

[0072] 100 parts per weight (e.g. 150 g) of a hydroxydimethyl silyl terminated polydimethyl siloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.77 parts (e.g. 1.15 g) of tetraethoxysilane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.02 parts of tetra n-butyl titanate (e.g.0.30 g) per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 151.45 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 11

[0073] The same method of preparation was utilised as described in Example 9 with the exception that 0.6 parts of 1, 6-bis(trimethoxysilyl)hexane per 100 parts by weight of the polymer was utilised as the cross-linker and 0.2 parts of tetra t-butyl titanate was added and the weight of the final mixture was 218.3 g

Example 12

[0074] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethyl siloxane polymer having a viscosity at 23° C. of 4000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.71 parts of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.15 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 100.86 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 13

[0075] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethyl siloxane polymer having a viscosity at 23° C. of 13,500 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 5 rpm) was introduced into a dental container followed by 0.47 parts of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.10 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 100.57 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 14

[0076] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethyl siloxane polymer having a viscosity at 23° C. of 50,000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-51 at 0.5 rpm) was introduced into a dental container followed by 0.33 part of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.07 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 100.40 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 15

[0077] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethyl siloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.7 part of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.25 parts of titanium diisopropoxide bis(ethylacetoacetate) per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 100.95 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%. The cured product is yellowing over time.

Example 16

[0078] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer partially trimethylsilyl terminated exhibiting viscosity at 23° C. of about 12,500 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 5 rpm) was introduced into a dental container followed by 0.37 part of 1, 6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.08 parts of tetra t-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 100.45 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 17

Preparation of a Two Part Mixture

[0079] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 50,000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-51 at 0.5 rpm) was introduced into a dental container followed by 0.62 parts of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm and filled in a 300 ml cartridge as part A of a two part composition. 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 50,000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-51 at 0.5 rpm) was introduced into a dental container followed by 0.08 parts of tetra n-butyl titanate per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm and filled in a 300 ml cartridge as part B of the two part composition.

[0080] A mixture 1:1 in weight of part A and Part B were mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 18

Preparation of a Two Part Mixture

[0081] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 13,500 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 5 rpm) was introduced into a dental container followed by 0.94 parts of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm and filled in a 300 ml cartridge as part A of a two part composition.

[0082] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 13,500 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 5 rpm) was introduced into a dental container followed by 0.16 parts of tetra n-butyl titanate per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm and filled in a 300 ml cartridge as part B of the two part composition.

[0083] A mixture 1:1 in weight of part A and Part B were mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Example 19

Preparation of a Two Part Mixture

[0084] 100 parts per weight of a trimethoxysilyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 56,000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 5 rpm) was introduced into a dental container 0.2 parts of tetra n-butyl titanate per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm and filled in a 300 ml cartridge as part A of a two part composition. The aforementioned trimethoxysilyl terminated polydimethylsiloxane polymer functions in this example as the cross-linker.

[0085] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 50,000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 5 rpm) was introduced in a 300 ml cartridge as part B of the two part composition.

[0086] A mixture 1:5 in weight of part A and Part B were mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

[0087] A series of comparative compositions were also prepared as described below:

Comparative Example 1

[0088] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.5 part of methyltrimethoxysilane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.08 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was 70 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in a Relative Humidity (RH) of 50%.

Comparative Example 2

[0089] The same method of preparation was utilised as described in Comparative Example 1 with the exception that 0.5 part of tetraethoxysilane per 100 parts by weight of the polymer was utilised as the cross-linker.

Comparative Example 3

[0090] The same method of preparation was utilised as described in Comparative Example 1 with the exception that 2.5 part of methyltrimethoxysilane per 100 parts by weight of the polymer was utilised as the cross-linker.

Comparative Example 4

[0091] The same method of preparation was utilised as described in Comparative Example 1 with the exception that 2.5 part of tetraethoxysilane per 100 parts by weight of the polymer was utilised as the cross-linker.

Comparative Example 5

[0092] The same method of preparation was utilised as described in Comparative Example 1 with the exception that 2.5 part of 1, 6-bis(trimethoxysilyl)hexane per 100 parts by weight of the polymer was utilised as the cross-linker.

Comparative Example 6

[0093] The same method of preparation was utilised as described in Comparative Example 1 with the exception that 0.5 part of methyltrioximino silane per 100 parts by weight of the polymer was utilised as the cross-linker.

Comparative Example 7

[0094] The same method of preparation was utilised as described in Comparative Example 1 with the exception that 0.5 part of a 50/50 by weight mixture of methyl triacetoxysilane and ethyl triacetoxysilane per 100 parts by weight of the polymer was utilised as the cross-linker.

Comparative Example 8

[0095] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.5 part of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.04 parts of tetra n-butyl titanate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was set to 70 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Comparative Example 9

[0096] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.5 part of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.08 parts of dimethyl tin neodecanoate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was set to 70 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

Comparative Example 10

[0097] 100 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s (Brookfield cone plate viscometer (RV DIII) using a cone plate CP-52 at 20 rpm) was introduced into a dental container followed by 0.5 part of 1,6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the polymer. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. Subsequently 0.08 parts of stannous octoate per 100 parts by weight of the polymer was added and the final mixture was stirred again in the speedmixer for a further 30 seconds at a speed of 2000 rpm. The total weight of the mixture was set to 70 g. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%.

[0098] The level of cure was observed after 4 days (4D) and 7 days (7D) in the Tables below. Each sample cured was tested for Penetration and Hardness as described below: Penetration was measured after 3 days of cure at a temperature 23° C. and 50% relative humidity using a Universal Penetrometer with a total weight of about 19.5 g after 5 seconds of penetration of the head in the material (ASTM D217-10 (2010)). Results are provided in 1/10mm and were measured a period of 7 days curing at 23° C. in an RH of 50%. Hardness was measured after 7 days (7D) of cure at a temperature 23° C. and 50% relative humidity according to ASTM D2240-05(2010) in the Shore 00 scale. The results of the above are depicted in the following Tables:

TABLE-US-00001 TABLE 1a Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Observation after 4 D CiD CiD CiD CiD CiD CiD Observation after 7 D CiD CiD CiD CiD CiD CiD Penetration (1/10 25 0 92 61 7 0 mm) after 7 D cure Hardness shore 00 0 18 0 0 0 13 after 7 D cure CiD = cure in depth.

TABLE-US-00002 TABLE 1b Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Observation after 4 D CiD CiD CiD CiD CiD CiD Observation after 7 D CiD CiD CiD CiD CiD CiD Penetration (1/10 106 8 37 27 35 50 mm) after 7 D cure Hardness shore 00 0 0 0 0 0 0 after 7 D cure

TABLE-US-00003 TABLE 1c Ex. Ex. Ex. Ex. Ex. Ex. Ex. 13 14 15 16 17 18 19 Observation after 4 D CiD CiD CiD CiD CiD CiD CiD Observation after 7 D CiD CiD CiD CiD CiD CiD CiD Penetration (1/10 50 62 0 107 47 7 31 mm) after 7 D cure Hardness shore 00 0 0 9 0 0 0 0 after 7 D cure

TABLE-US-00004 TABLE 2a Comparative Examples C Ex. 1 C Ex. 2 C Ex. 3 C Ex. 4 C Ex. 5 C Ex. 6 Observation No cure No cure Top skin Top skin Top skin No cure after 4 D cure not in cure not in cure not in bulk Cure bulk Cure bulk Cure like a one like a one like a one part part part elastomer elastomer elastomer Observation No cure No cure Cure in Cure in Cure in No cure after 7 D depth depth depth Hardness Not Not 55 45 48 Not shore 00 measured measured measured after 7 D cure

TABLE-US-00005 TABLE 2b Comparative Examples C Ex 7 C Ex 8 C Ex 9 C Ex 10 Observation after No cure No cure No cure Very gelly 4 D Observation after No cure Cured Cured like Cured 7 D a one part Penetration ( 1/10 Not measured 116 7 10 mm) after 7 D cure

[0099] Comparative examples 1 and 2 may be directly compared to Examples 1 to 2 and it is noticeable that halving the amount of monosilane cross-linker resulted in no cure. Disilane cross-linkers appeared to be more efficient in the curing process than monosilane cross-linkers. Comparative examples 3 to 5 were provided to demonstrate that above a certain level of crosslinker there is no cure in bulk in the system but merely a skin cure that occurs through a moisture diffusion process as might usually be expected in condensation cure systems. Such composition could not be formulated to provide bulk cure like the typical two part moisture curing systems.

[0100] Comparative examples 6 and 7 should be compared with examples 7 and 8 and show the lower limit of crosslinker for oxime and acetoxy curing system respectively below which no cure is observed.

[0101] Comparative example 8 is to be compared to example 4 and provides the lower limit of titanate to be added in the system below which no cure is observed. At this level very slow cure is observed and the material is very soft. Comparative example 9 and 10 is comparable to example 4 and is showing that a tin IV catalyst is leading to a skin curing system and not to a bulk cure and the tin II is leading to a bulk cure but at a very low curing rate, which highlights that titanate catalyst works better for this system.

[0102] In a second embodiment there is provided a dual cure system in which there is provided a mixture of a condensation curable polymer and a hydrosilylation curable polymer, which are respectively cured using a condensation cross-linker and catalyst and using a hydrosilylation cross-linker and catalyst which results in cured end product being cured partially via a condensation pathway and partially via a hydrosilylation pathway

Example 20

Preparation of a Two Part Dual Cure Mixture

[0103] 50 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 2000 mPa.Math.s was introduced into a dental container followed by 50 parts per weight of a dimethylvinyl silyl terminated polydimethylsiloxane polymer per 50 parts by weight of hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 450 mPa.Math.s. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. 0.5 parts per weight of 1, 6-bis(trimethoxysilyl)hexane cross-linker per 100 parts by weight of the total polymer weight was introduced into the mixture and the resulting mixture was again stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. 0.9 parts per weight of a trimethylsiloxy-terminated polydiorganosiloxane having an average of five methylhydrogensiloxane units and three dimethylsiloxane units per molecule with a silicon-bonded hydrogen atom content of about 0.7 to 0.8 weight percent was then introduced and the resulting mixture was again stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. The final composition was filled in a 300 ml cartridge as part A of a two part composition.

[0104] 50 parts per weight of a silanol terminated polydimethylsiloxane polymer exhibiting a viscosity at 23° C. of about 2,000 mPa.Math.s has been added in a dental container followed by the addition of 50 parts per weight of a vinyl terminated polydimethylsiloxane polymer exhibiting a viscosity at 23° C. of about 450 mPa.Math.s per 50 parts per weight of a silanol terminated polydimethylsiloxane polymer. The mixture was then mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. Then 0.016 parts per weight of platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane has been added in the mixture and mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. Finally, 0.08 parts per weight of tetra t-butyl titanate was added in the mixture and then mixed in a speedmixer for 30 seconds at a speed of 2000 rpm and filled in a 300 ml cartridge as part B.

[0105] 50 parts per weight of a hydroxydimethyl silyl terminated polydimethylsiloxane polymer having a viscosity at 23° C. of 13,500 mPa.Math.s was introduced into a dental container followed by 50 parts per weight of a dimethylvinyl silyl terminated polydimethylsiloxane polymer per 50 parts, per weight of the hydroxydimethyl silyl terminated polydimethylsiloxane polymer, having a viscosity at 23° C. of 450 mPa.Math.s. The resulting mixture was then stirred in a speedmixer for 30 seconds at a speed of 2000 rpm. 0.016 parts per weight of the total polymer weight in Part B Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane was added in the mixture with the resulting mixture being mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. Finally, 0.08 parts per weight of tetra t-butyl titanate was added and the final mixture was also mixed in a speedmixer for 30 seconds at a speed of 2000 rpm and subsequently then filled in a 300 ml cartridge as part B of the two part composition.

[0106] A mixture 1:1 in weight of part A and Part B were mixed in a speedmixer for 30 seconds at a speed of 2000 rpm. The mixture was poured in a 50 ml aluminium cup and cured at 23° C. in an RH of 50%. The resulting cured material was noted to be cured in bulk in about 12 minutes and after 7 days of cure had a hardness of Shore 00 (measured as described above) of 40.