Silicone elastomer composition

• US 20070106016A1
• Filed: 11/09/2005
• Published: 05/10/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Momentive Performance Materials Incorporated (Momentive Performance Materials Holdings LLC)
• Original Assignee: Momentive Performance Materials Incorporated (Momentive Performance Materials Holdings LLC)
• Inventors: Zhu, Aijun
• Granted Patent: US 7,479,522 B2
• Time in Patent Office: Days
• US Class Current: 524/588
• CPC Class Codes: A43B 13/04 Plastics, rubber or vulcanised fibre
• CPC Class Codes: A61L 29/06 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: C08F 283/12 on to polysiloxanes
• CPC Class Codes: C08F 290/068 Polysiloxanes
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/70 Siloxanes defined by use of the MDTQ nomenclature
• CPC Class Codes: C08G 77/80 Siloxanes having aromatic substituents, e.g. phenyl side groups
• CPC Class Codes: C08L 2205/035 containing four or more polymers in a blend
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• CPC Class Codes: C08L 2666/54 Inorganic substances
• CPC Class Codes: C08L 51/085 on to polysiloxanes
• CPC Class Codes: C08L 83/00 Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 83/04 Polysiloxanes

Abstract

High tear strength, low hardness silicone elastomer-forming composition is provided using a unique combination(s) of polyorganosiloxanes and organohydrogenpolysiloxanes, where the polyorganosiloxanes and the organohydrogenpolysiloxanes contain both straight-chain and resinous polyorganosiloxanes.

Claims

1. A curable high tear strength, low hardness silicone elastomer-forming composition comprising:

(A) at least two organopolysiloxanes each independently containing at least two silicon-bonded alkenyl groups per molecule, provided said at least two organopolysiloxanes (A) contain at least one substantially straight chain organopolysiloxane and at least one substantially resinous organopolysiloxane;

(B) at least two organohydrogenpolysiloxanes each independently containing at least two silicon-bonded hydrogen atoms per molecule, provided said at least two organohydrogenpolysiloxanes (B) contain at least one substantially straight chain organohydrogenpolysiloxane and at least one substantially resinous organohydrogenpolysiloxane said at least two organohydrogenpolysiloxanes (B) being used in an amount such that the mole ratio of total amount of silicon-bonded hydrogen atoms contained in at least two organohydrogenpolysiloxanes (B) to one silicon-bonded alkenyl group contained in at least two organopolysiloxanes (A) is of from about 1.3 to about 2.2;

(C) filler in an amount of from about 15 to about 45 parts per hundred of polyorganosiloxane (A);

(D) catalyst; and

,

(E) inhibitor, and where combined (A)-(E) comprises a curable high tear strength, low hardness silicone elastomer-forming composition.

2. The curable high tear strength, low hardness silicone elastomer forming composition of claim 1 where at least two organopolysiloxanes (A) comprises the reaction product of linear polyorganosiloxane, branched polyorganosiloxane, and three-dimensional network polyorganosiloxane.

3. The curable high tear strength, low hardness silicone elastomer forming composition of claim 1 where at least two polyorganosiloxanes (A) can further comprise, in addition to at least two polyorganosiloxanes that independently contain at least two silicon-bonded alkenyl groups per molecule and at least one substantially straight chain organopolysiloxane and at least one substantially resinous organopolysiloxane;

non-alkenyl containing polyorganosiloxane selected from the group consisting of linear polyorganosiloxane, branched polyorganosiloxane, cyclic organopolysiloxane, three-dimensional network polyorganosiloxane, resinous polyorganosiloxane and combinations thereof where each polyorganosiloxane does not contain any alkenyl groups.

4. The curable high tear strength, low hardness silicone elastomer forming composition of claim 1 where substantially straight chain polyorganosiloxane is polyorganosiloxane that comprises less than about 30 weight percent of T and/or Q units where T=R⁶SiO_3/2 and Q=SiO_4/2 where R⁶ is selected from the group consisting of a monovalent hydrocarbon radical of from one to about sixty carbon atoms;

an unsaturated monovalent hydrocarbon radical containing from 2 to 10 carbon atoms; and

combinations thereof.

5. The curable high tear strength, low hardness silicone elastomer forming composition of claim 1 where substantially resinous polyorganosiloxane is polyorganosiloxane that comprises no less than about 30 weight percent, of T and/or Q units where where T=R⁶SiO_3/2 and Q=SiO_4/2 where R⁶ is selected from the group consisting of a monovalent hydrocarbon radical of from one to about sixty carbon atoms;

an unsaturated monovalent hydrocarbon radical containing from 2 to 10 carbon atoms; and

combinations thereof.

6. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where each of substantially straight chain organopolysiloxane and substantially resinous organopolysiloxane has a viscosity of from about 10 to about 1,000,000 centipoise at 25 degrees celsius and has the formula:

M_aM^vi_bD_cD^vi_dT_eT^vi_fQ_g

where

M=R⁷R⁸R⁹SiO_1/2;

M^vi=R¹⁰R¹¹R¹²SiO_1/2;

D=R¹³R¹⁴SiO2/2;

D^vi=R¹⁵R¹⁶SiO_2/2;

T=R¹⁷SiO_3/2;

T^vi=R¹⁸SiO_3/2; and

Q=SiO_2/2;

where R⁷, R⁸, R⁹, R¹³, R¹⁴ and R¹⁷ are independently monovalent hydrocarbon radicals having from one to sixty carbon atoms;

R¹⁰ is a monovalent unsaturated hydrocarbon radical having from two to ten carbon atoms, and R¹¹ and R¹² are independently monovalent hydrocarbon radicals having from one to sixty carbon atoms;

R¹⁵ is a monovalent unsaturated hydrocarbon radical having from two to ten carbon atoms and R¹⁶ is a monovalent hydrocarbon radical having from one to sixty carbon atoms;

R¹⁷ is a monovalent unsaturated hydrocarbon radical having from two to ten carbon atoms;

the stoichiometric subscripts a, b, c, d, e, f, and g are either zero or positive subject to the following limitations;

c is greater than10;

d is from zero to about 20;

when d=0, b=2;

b is from zero to two, provided that when b=0, d=2;

b+d is of from 2 to about 20, when b=1, a=1;

a+b≧

2; and

in substantially straight chain organopolysiloxane if e+f+g>

0, then a+b+c+d>

e+f+g; and

in substantially resinous organopolysiloxane if e+f+g>

0, then a+b+c+d<

e+f+g; and

organopolysiloxane (A) contains at least two silicon-bonded alkenyl groups per molecule.

7. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where at least two silicon-bonded alkenyl groups contain from 1 to about 6 carbon atoms.

8. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where at least two silicon-bonded alkenyl groups are vinyl.

9. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where organo groups of at least two polyorganosiloxanes (A) comprise methyl and/or phenyl.

10. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where at least two organohydrogenpolysiloxanes (B) comprises the reaction product of linear organohydrogenpolysiloxane, branched organohydrogenpolysiloxane, cyclic organohydrogenpolysiloxane and three-dimensional network organohydrogenpolysiloxane.

11. The curable high tear strength, low hardness silicone elastomer forming composition of claim 1 where substantially straight chain organohydrogenpolysiloxane is organohydrogenpolysiloxane that comprises less than about 30 weight percent of T and/or Q units where T=R²⁴SiO_3/2 and Q=SiO_4/2, where R²⁴ is selected from the group consisting of a monovalent hydrocarbon radical of from one to about sixty carbon atoms;

an unsaturated monovalent hydrocarbon radical containing from 2 to 10 carbon atoms; and

combinations thereof.

12. The curable high tear strength, low hardness silicone elastomer forming composition of claim 1 where substantially resinous organohydrogenpolysilxoane is organohydrogenpolysiloxane that comprises no less than about 30 weight percent, of T and/or Q units where where T=R²⁴SiO_3/2 and Q=SiO_4/2, where R²⁴ is selected from the group consisting of a monovalent hydrocarbon radical of from one to about sixty carbon atoms;

an unsaturated monovalent hydrocarbon radical containing from 2 to 10 carbon atoms; and

combinations thereof.

13. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where each substantially straight chain organohydrogenpolysiloxane and each substantially resinous organohydrogenpolysiloxane has the formula:

M_hM^H_iD_jD^H_kT_LT^H_mQ_n

where

M=R²⁷R²⁸R²⁹SiO_1/2;

M^H=R³⁰R³¹HSiO_1/2;

D=R³²R³³SiO_2/2;

D^H=R³⁴HSiO_2/2;

T=R³⁵SiO_3/2;

T^H=HSiO_3/2; and

Q=SiO_4/2;

where R²⁷,R²⁸, R²⁹, R³², R³³, and R³⁵ are independently monovalent hydrocarbon radicals having from one to sixty carbon atoms and are substantially free of aliphatic unsaturation;

R³⁰, R³¹, and R³⁴ are independently monovalent hydrocarbon radicals having from one to sixty carbon atoms or hydrogen and are substantially free of aliphatic unsaturation the stoichiometric subscripts h, i, j, k, L, m and n being zero or positive subject to the following limitations;

j is greater than 0;

k is of from zero to about 20, when k=0, i=2;

h is of from zero to about 2;

subject to the further limitation that i+k is of from 2 to about 20, when i=1, h=1;

h+i≧

2; and

in at least one substantially straight chain organohydrogenpolysiloxane if L+m+n>

0 then h+i+j+k>

L+m+n; and

in at least one substantially resinous organohydrogenpolysiloxane when L+m+n>

0, then L+m+n>

h+i+j+k and each of at least two organohydrogenpolysiloxanes (B) contains at least two silicon-bonded hydrogen atoms per molecule.

14. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where each substantially straight chain organohydrogenpolysiloxane and each substantially resinous organohydrogenpolysiloxane has a viscosity of from about 0.1 to about 2000 centipoise at 25 degrees Celsius.

15. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where each of at least one substantially straight chain organohydrogenpolysiloxane and at least one substantially resinous organohydrogenpolysiloxane has a viscosity of from about 0.5 to about 1000 centipoise at 25 degrees celsius.

16. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where each of at least one substantially straight chain organohydrogenpolysiloxane and at least one substantially resinous organohydrogenpolysiloxane has a viscosity of from 1 to about 500 centipoise at 25 degrees celsius.

17. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where mole ratio of total amount of silicon-bonded hydrogen atoms contained in at least two organohydrogenpolysiloxanes (B) to one silicon-bonded alkenyl group contained in at least two organopolysiloxanes (A) is of from about 1.4 to about 2.0.

18. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where mole ratio of total amount silicon-bonded hydrogen atoms contained in at least two organohydrogenpolysiloxanes (B) to one silicon-bonded alkenyl group contained in at least two organopolysiloxanes (A) is of from about 1.5 to about 1.8.

19. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where filler (C) is present in an amount of from about 20 to about 40 parts by weight per 100 parts of at least two organopolysiloxanes (A).

20. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where filler (C) is present in an amount of from about 25 to about 35 parts by weight per 100 parts of at least two organopolysiloxanes (A).

21. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where filler is selected from the group consisting of silica, fumed silica, precipitated silica, titania, alumina, clay, wollastonite quartz, and combinations thereof.

22. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where catalyst (D) is at least one Group VIIIB catalyst.

23. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 where inhibitor (E) contains aliphatic unsaturation and is selected from the group consisting of diallyl maleate, D-4 vinyl, 2-methyl-3-butene-2-ol, 1-ethynyl-1-cyclohexanol, 3,5,-dimethyl-1-hexyn-3-ol and combinations thereof.

24. The curable high tear strength, low hardness silicone elastomer-forming composition of claim 1 comprising the specific formulation where at least two organopolysiloxanes (A) is a combination of (A-i) substantially straight chain vinyl organopolysiloxane having a viscosity of from about 50,000 to about 80,000 centipoise at 25 degrees celsius, and being present in an amount of from about 45 to about 50 weight percent;

(A-ii) substantially straight chain vinyl organopolysiloxane having a viscosity of from about 20,000 to about 45,000 centipoise at 25 degrees celsius, and being present in an amount of from about 20 to about 25 weight percent;

(A-iii) substantially resinous vinyl organopolysiloxane having a viscosity of from about 15 to about 250 centipoise at 25 degrees celsius, and being present in an amount of from about 1.5 to about 2.5 weight percent;

at least two organohydrogenpolysiloxanes (B) is a combination of (B-i) substantially straight chain organohydrogenpolysiloxane where (B-i) has terminal group silicon-bonded hydrogen atom and additional silicon-bonded hydrogen atom beyond terminal group silicon-bonded hydrogen atom per molecule and having a viscosity of from about 15 to about 100 centipoise at 25 degrees celsius, being present in an amount of from about 0.5 to about 1 weight percent; and

(B-ii) is substantially straight chain organohydrogenpolysiloxane containing silicon-bonded hydrogen atoms that are only terminal group silicon-bonded hydrogen atoms per molecule and having a viscosity of from 1 to about 10 centipoise at 25 degrees celsius, being present in an amount of from about 0.5 to about 1 weight percent; and

(B-iii) substantially resinous organohydrogenpolysiloxane having a viscosity of from about 15 to about 60 centipoise at 25 degrees celsius, and being present in an amount of from about 1.5 to about 2.5 weight percent;

filler (C) being fumed silica with a surface area of from about 200 to about 350 m²/g, said fumed silica having been treated with silane, where filler (C) is present in an amount of from about 20 to about 25 weight percent;

catalyst (D) is a platinum catalyst where catalyst (D) is present in an amount of from about 5 ppmto about 30 ppm and, inhibitor (E) is 1-ethynyl-1-cyclohexanol where inhibitor (E) is present in an amount of from about 0.02 to about 0.06 weight percent, with all weight percents being based upon the total weight of the curable high tear strength, low hardness silicone elastomer-forming composition.

25. The high tear strength, low hardness silicone elastomer obtained from the curing of the curable high tear strength, low hardness silicone elastomer-forming composition of claim 1.

26. The high tear strength, low hardness silicone elastomer of claim 25 where the high tear strength, low hardness silicone elastomer is liquid injection moldable silicone elastomer.

27. The high tear strength, low hardness silicone elastomer of claim 25 where the elastomer has a tear B value of at least about 180 ppi and a Shore A hardness of less than about 40.

28. The high tear strength, low hardness silicone elastomer of claim 25 where the elastomer has a tear B value of at least about 200 ppi and a Shore A hardness of less than about 35.

29. The liquid injection moldable silicone elastomer of claim 26 where the elastomer has a tear B value of at least about 220 ppi and a Shore A hardness of less than about 33.

30. The high tear strength, low hardness silicone elastomer of claim 25 where the elastomer is used in an application selected from the group consisting of sleep apnea masks, needle-less intravenous applications, peristaltic pump membranes, shoe insoles and catheter balloons.