SILICONE RUBBER SYNTACTIC FOAM

Abstract

The present invention relates to a novel silicone rubber syntactic foam and the silicone precursor of said foam.

Claims

1. An addition curing type organopolysiloxane composition X comprises: a) at least one organopolyosiloxane A of the following formula: ##STR00003## in which: R and R, are chosen independently of one another from the group consisting of C.sub.1 to C.sub.30 hydrocarbon radical, and optionally R is an alkyl group chosen from the group consisting of methyl, ethyl, propyl, trifluoropropyl, and phenyl, and optionally R is a methyl group, R is a C.sub.1 to C.sub.20 alkenyl radical, and optionally R is chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally R is a vinyl radical, R is an alkyl group such as a methyl, ethyl, propyl, trifluoropropyl, phenyl, and optionally R is a methyl group, and n is an integer having a value from 5 to 1000, and optionally from 5 to 100, b) at least one silicon compound B comprising at least two hydrogen atoms bonded to silicon per molecule, and optionally a mixture of two silicon compounds B one comprising two telechelic hydrogen atoms bonded to silicon per molecule with no pendent hydrogen atoms bonded to silicon per molecule and the other comprising at least three hydrogen atoms bonded to silicon per molecule, c) an effective amount of hydrosilylation catalyst C, and optionally a platinum based hydrosilylation catalyst C. d) hollow glass beads D, and optionally hollow borosilicate glass microspheres, e) at least one reactive diluent E for reducing the viscosity of the composition and which reacts through hydrosilylation reaction and is chosen from the group consisting of: a silicon compound comprising a single silicon hydride group per molecule, and an organic compound containing a single ethylenically unsaturated group, optionally said organic compound is an organic ?-olefin containing from 3 to 20 carbon atoms, and optionally chosen from the group consisting of dodecene, tetradecene, hexadecene, octadecene and a combination of these and all with a terminal vinyl group, an organopolysiloxane having a single telechelic alkenyl group, and optionally said telechelic alkenyl group is chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally is a vinyl group, f) optionally at least one additive H optionally a pigment, a dye, clays, a surfactant, hydrogenated castor oil, wollastonite, aluminium trihydrate, magnesium hydroxide, halloysite, huntite hydromagnesite, expandable graphite, zinc borate, mica or a fumed silica, and g) optionally at least one cure rate controller G which slows the curing rate.

2. An addition curing type organopolysiloxane composition X according to claim 1, wherein hollow glass beads are hollow borosilicate glass microspheres.

3. An addition curing type organopolysiloxane composition X according to claim 2, wherein the hollow borosilicate glass microspheres have true density ranging from 0.10 gram per cubic centimeter to 0.65 gram per cubic centimeter.

4. An addition curing type organopolysiloxane composition X according to claim 1, wherein the level of hollow glass beads is up to 80% volume loading in the silicone rubber syntactic foam, and preferably between 5% and 70% by volume loading of the silicone rubber syntactic foam.

5. An addition curing type organopolysiloxane composition X according to claim 1, wherein the reactive diluent E: is chosen from the group consisting of dodecene, tetradecene, hexadecene, octadecene or a combination of these and all having a terminal vinyl group, or is a liquid organopolysiloxane with formula I ##STR00004## In which: R are R.sup.2, are chosen independently of one another from a C.sub.1 to C.sub.30 hydrocarbon radical, and optionally are chosen from the group consisting of methyl, ethyl, propyl, trifluoropropyl and phenyl, and optionally are methyl groups, R.sup.1 is a C.sub.1 to C.sub.20 alkenyl radical, and optionally R.sup.1 is chosen from the group consisting of vinyl, allyl, hexenyl, decenyl, or tetradecenyl, and optionally R.sup.1 is vinyl, and x is between 0 and 100, and is chosen so that it will lower the viscosity of addition curing type organopolysiloxane composition X compared to same composition without the reactive diluent.

6. An addition curing type organopolysiloxane composition X according to claim 1, wherein: the viscosity at 25? C. of said organopolysiloxane A is between 5 mPa.Math.s and 60000 mPa.Math.s; and optionally between 5 mPa.Math.s and 5000 mPa.Math.s, and optionally between 5 mPa.Math.s and 350 mPa.Math.s, and the viscosity at 25? C. of said silicon compound B comprising two telechelic hydrogen atoms bonded to silicon per molecule with no pendent hydrogen atoms bonded to silicon per molecule is between 5 and 100 mPa.Math.s, and the viscosity at 25? C. of said silicon compound B comprising at least three hydrogen atoms bonded to silicon per molecule is between 5 and 2000 mPa.Math.s.

7. An addition curing type organopolysiloxane composition X according to claim 1, wherein the viscosities at 25? C. of said organopolysiloxane A and said silicon compound B comprising at least two hydrogen atoms bonded to silicon per molecule are chosen so that the viscosity at 25? C. of the addition curing type organopolysiloxane composition X is between 500 mPa.Math.s to 5000 mPa.Math.s and optionally between 500 mPa.Math.s to 2500 mPa.Math.s.

8. An addition curing type organopolysiloxane composition X according to claim 1, wherein the proportions in weight of the organopolysiloxane A, the reactive diluent E and the silicon compound B are such that the overall molar ratio of the hydrogen atoms bonded to the silicon to the overall alkenyl radicals bonded to the silicon is within a range from 0.35 to 10, and optionally within a range from 0.4 to 1.5.

9. An addition curing type organopolysiloxane composition X according to claim 1 which is stored before use as a multi-component RTV comprising at least two separate packages which are optionally airtight, whereas the hydrosilylation catalyst C is not present in the same package with silicon compound B or with reactive diluent E when it is a silicon compound comprising a single silicon hydride group per molecule.

10. An addition curing type organopolysiloxane composition X according to claim 1 which is stored before use as a multi-component RTV comprising at least two separate packages which are optionally airtight: a) the first package A1 comprising: 100 parts by weight of at least one organopolysiloxane A, from 5 to 30 parts by weight of hollow glass beads D, and from 5 to 30 parts by weight of at least one reactive diluent E, and from 4 to 150 ppm based on metal platinum of a platinum based hydrosilylation catalyst C. b) the second package A2 comprising: 100 parts by weight of at least one organopolysiloxane A, from 10 to 70 parts by weight of a silicon compounds B one comprising two telechelic hydrogen atoms bonded to silicon per molecule, from 5 to 25 parts by weight of a silicon compounds B comprising at least three hydrogen atoms bonded to silicon per molecule, from 5 to 30 parts by weight of hollow glass beads D, which is stored before use as a multi-component RTV comprising at least two separate packages which are optionally airtight, whereas the hydrosilylation catalyst C is not present in the same package with silicon compound B or with reactive diluent E when it is a silicon compound comprising a single silicon hydride group per molecule and an effective amount of at least one cure rate controller G which slows the curing rate.

11. A silicone rubber syntactic foam obtained by crosslinking said addition curing type organopolysiloxane composition X as defined in claim 1.

12. A process for the preparation of the addition curing type organopolysiloxane composition X according to claim 1 comprising: a) feeding into a base feed line a liquid silicone base MS1 comprising: i) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups, ii) hollow glass beads D, and optionally hollow borosilicate glass microspheres D1, iii) at least one silicon compound B having at least two and optionally at least three hydrogen atoms bonded to silicon per molecule, iv) at least one reactive diluent E for reducing the viscosity of the composition and which reacts through hydrosilylation reaction and is chosen from the group consisting of: a silicon compound comprising a single silicon hydride group per molecule, and an organic compound containing a single ethylenically unsaturated group, optionally said organic compound is an organic ?-olefin containing from 3 to 20 carbon atoms, and optionally chosen from the group consisting of dodecene, tetradecene, hexadecene, octadecene and a combination of these and all with a terminal vinyl group, and an organopolysiloxane having a single telechelic alkenyl group, and optionally said telechelic alkenyl group is chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally is a vinyl group, and v) optionally a cure rate controller G which slows the curing rate, b) feeding into a catalyst feed line a catalyst master batch MC comprising: i) at least one hydrosilylation catalyst C; and ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most optionally said alkenyl groups are vinyl groups; c) feeding into an inhibitor feed line an inhibitor master batch MI comprising: i) a cure rate controller G which slows the curing rate; and ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally said alkenyl groups are vinyl groups; and d) optionally feeding into an additive feed line an additive masterbatch MA comprising: i) at least one additive H such as a pigment, a dye, clays, a surfactant, hydrogenated castor oil, wollastonite, aluminium trihydrate, magnesium hydroxide, halloysite, huntite, hydromagnesite, expandable graphite, zinc borate, mica or a fumed silica, and ii) optionally at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally said alkenyl groups are vinyl groups; and e) directing said liquid silicone base MS1, said catalyst master batch MC and said inhibitor master batch MI and optionally said additive masterbatch MA into a tank to obtain the addition curing type organopolysiloxane composition X.

13. A process for the preparation of the addition curing type organopolysiloxane composition X according to claim 1 comprising: a) feeding into a base feed line a liquid silicone base MS2 comprising: i) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most optionally said alkenyl groups are vinyl groups, and ii) at least one silicon compound B having at least two and optionally at least three hydrogen atoms bonded to silicon per molecule, iii) optionally a cure rate controller G which slows the curing rate, iv) at least one reactive diluent E for reducing the viscosity of the composition and which reacts through hydrosilylation reaction and is chosen from the group consisting of: a silicon compound comprising a single silicon hydride group per molecule, and an organic compound containing a single ethylenically unsaturated group, optionally said organic compound is an organic ?-olefin containing from 3 to 20 carbon atoms, and optionally chosen from the group consisting of dodecene, tetradecene, hexadecene, octadecene and a combination of these and all with a terminal vinyl group, and an organopolysiloxane having a single telechelic alkenyl group, and optionally said telechelic alkenyl group is chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally is a vinyl group, and b) feeding into a catalyst feed line a catalyst master batch MC comprising: i) at least one hydrosilylation catalyst C; and ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally said alkenyl groups are vinyl groups; c) feeding into an inhibitor feed line an inhibitor master batch MI comprising: i) a cure rate controller G which slows the curing rate; and ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally said alkenyl groups are vinyl groups; and d) optionally feeding into an additive feed line an additive masterbatch MA comprising: i) at least one additive H optionally a pigment, a dye, clays, a surfactant, hydrogenated castor oil, wollastonite, aluminium trihydrate, magnesium hydroxide, halloysite, huntite hydromagnesite, expandable graphite, zinc borate, mica or a fumed silica, and ii) optionally at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, optionally said alkenyl groups are chosen from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and optionally said alkenyl groups are vinyl groups; e) directing said liquid silicone base MS2, said catalyst master batch MC and said inhibitor master batch MI and optionally said additive masterbatch MA into a stirring tank; and f) operating said stirring tank, thereby mixing said liquid silicone base MS1, said catalyst master batch MC and said inhibitor master batch MI and optionally said additive masterbatch MA optionally by using a high flow, low-shear mixer, and g) adding hollow glass beads D and preferably hollow borosilicate glass microspheres D1 into said stirring tank, optionally by means using gravity discharge or screw feeder to obtain the addition curing type organopolysiloxane composition X.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0156] FIGS. 1 and 2 provide a schematic representation of two preferred embodiments of a method for producing an addition curing type organopolysiloxane composition X wherein the inhibitor master batch MI and catalyst master batch MC are separately fed into other components so as to control the curing rate.

[0157] FIG. 1 shows a method for producing an addition curing type organopolysiloxane composition X according to one embodiment of the invention wherein said liquid silicone base MS1 is stored in a storage tank 1, said catalyst master batch MC is stored in a storage tank 20, said inhibitor master batch MI is stored in a storage tank 50 and said additive masterbatch MA is stored in a storage tank 65 and are fed separately into their respective feed lines 200, 210, 220 and 230 respectively. The storage tank 1 of the liquid silicone base MS2 is connected to the stirring tank 80 via a feed pump 10, which can be any large displacement pump, and via an optional feed rate adjuster 15. The storage tank 20 of the catalyst master batch MC is connected to the stirring tank 80 via a feed pump 25, which can be any small piston displacement pump, gear pump, micro motion injector pump, or other positive displacement pump, and via an optional feed rate adjuster 30. The storage tank 50 of the inhibitor master batch MI is connected to the stirring tank 80 via a feed pump 55, which can be any small piston displacement pump, gear pump, micro motion injector pump, or other positive displacement pump, and via an optional feed rate adjuster 60. The storage tank 65 of the additive masterbatch MA is connected to the stirring tank 80 via a feed pump 70, which can be any small piston displacement pump, gear pump, micro motion injector pump, or other positive displacement pump, and via an optional feed rate adjuster 75. When said liquid silicone base MS2, said catalyst master batch MC and said inhibitor master batch MI and optionally said additive masterbatch MA are directed into said stirring tank 80; the resulting mixture is mixed preferably by using a high flow, low-shear mixer to yield the addition curing type organopolysiloxane composition X according to the invention. Said composition is now available to be introduced into for example a battery module casing of an electric battery by mean 100 which could be either via an injection apparatus or via a pump to allow free flow to fill the free spaces of said battery module casing and cures via crosslinking.

[0158] FIG. 2 shows a method for producing an addition curing type organopolysiloxane composition X according to another embodiment of the invention wherein said liquid silicone base MS2 is stored in a storage tank 1, said catalyst master batch MC is stored in a storage tank 20, said inhibitor master batch MI is stored in a storage tank 50 and said additive masterbatch MA is stored in a storage tank 65 and are fed separately into their respective feed lines 200, 210, 220 and 230 respectively. The storage tank 1 of the liquid silicone base MS2 is connected to the stirring tank 80 via a feed pump 10, which can be any large displacement pump, and via an optional feed rate adjuster 15. The storage tank 20 of the catalyst master batch MC is connected to the stirring tank 80 via a feed pump 25, which can be any small piston displacement pump, gear pump, micro motion injector pump, or other positive displacement pump, and via an optional feed rate adjuster 30. The storage tank 50 of the inhibitor master batch MI is connected to the stirring tank 80 via a feed pump 55, which can be any small piston displacement pump, gear pump, micro motion injector pump, or other positive displacement pump, and via an optional feed rate adjuster 60. The storage tank 65 of the additive masterbatch MA is connected to the stirring tank 80 via a feed pump 70, which can be any small piston displacement pump, gear pump, micro motion injector pump, or other positive displacement pump, and via an optional feed rate adjuster 75. When said liquid silicone base MS2, said catalyst master batch MC and said inhibitor master batch MI and optionally said additive masterbatch MA are directed into said stirring tank 80; the resulting mixture is mixed preferably by using a high flow, low-shear mixer. To said resulting mixture, hollow glass beads D and preferably hollow borosilicate glass microspheres D1 which are stored in storage tank 90, which is preferably a hopper, are transferred into said stirring tank 80 either directly by gravity discharge or via screw feeder 95 to yield addition curing type organopolysiloxane composition X according to the invention. Said composition is now available to be introduced into for example a battery module casing of an electric battery by mean 100 which could be either via an injection apparatus or via a pump to allow free flow to fill the free spaces of said battery module casing and cures via crosslinking.

[0159] Other advantages provided by the present invention will become apparent from the following illustrative examples.

EXAMPLES

I) Definition of the Components

[0160] Organopolysiloxane A1=polydimethylsiloxane with dimethylvinylsilyl end-units with a viscosity at 25? C. ranging from 80 mPa.Math.s to 120 mPa.Math.s;
Organopolysiloxane A2=polydimethylsiloxane with dimethylvinylsilyl end-units with a viscosity at 25? C. ranging from 500 mPa.Math.s to 650 mPa.Math.s; [0161] Organopolysiloxane 131 (CE) as chain extender=polydimethylsiloxane with dimethylsilylhydride end-units with a viscosity at 25? C. ranging from 7 mPa.Math.s to 10 mPa.Math.s and formula: MD.sub.xM
In which: [0162] D is a siloxy unit of formula (CH.sub.3).sub.2SiO.sub.2/2 [0163] M is a siloxy unit of formula (CH.sub.3).sub.2(H)SiO.sub.1/2 [0164] and x is an integer ranging from 8 to 11; [0165] Organopolysiloxane B2 (XL) as crosslinker, with a viscosity at 25? C. ranging from 18 mPa.Math.s to 26 mPa.Math.s, over 10 SiH reactive groups are present (in average from 16 to 18 SiH reactive groups): poly(methylhydrogeno) (dimethyl)siloxane with SiH groups in-chain and end-chain (?/?), [0166] Hollow glass beads D1: 3M? Glass Bubbles Series S15, sold by 3M Company, Particle Size (50%) microns by volume=55 microns, Isostatic Crush Strength: Test Pressure 300 psi (2.07 MPa.), True Density (g/cc)=0.15. [0167] Hollow glass beads D2: 3M? iM16K Glass Bubbles, sold by 3M Company, (Particle Size (50%) microns by volume=20 microns, Isostatic Crush Strength Test Pressure 16,000 psi, True Density (g/cc)=0.46. [0168] Cure rate controller G1: 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane. [0169] Cure rate controller G2: 1-Ethynyl-1-cyclohexanol (ECH). [0170] Cure rate controller G3-MB: 90% by weight of Organopolysiloxane A1 and 10% by weight of cure rate controller G2. [0171] Catalyst C: 10% platinum as Karstedt catalyst in 350 cS dimethylvinyldimer, sold by Johnson Matthey Company. [0172] Catalyst C-MB: 98% by weight of Organopolysiloxane A1 and 2% by weight of Catalyst C. [0173] Reactive diluent E=1-tetradecene.

TABLE-US-00001 TABLE 1 Inventive two-parts formulation 1 precursor of a silicone rubber syntactic foam Parts by weight Part A Organopolysiloxane A1 81.88 Reactive diluent E 5.03 Catalyst C 0.037 hollow glass beads D1 13.05 Part B Organopolysiloxane A1 81.88 Organopolysiloxane B2 (XL) 8.6 Organopolysiloxane B1 (CE) 53.41 Cure rate controller G1 0.01 hollow glass beads D1 13.05

TABLE-US-00002 TABLE 2 Inventive two-parts formulation 2 precursor of a silicone rubber syntactic foam. Parts by weight Part A Organopolysiloxane A1 78.27 Reactive diluent E 8.62 Catalyst C 0.063 hollow glass beads D1 13.05 Part B Organopolysiloxane A1 69.23 Organopolysiloxane B2 (XL) 2.46 Organopolysiloxane B1 (CE) 15.26 Cure rate controller G1 0.0029 hollow glass beads D1 13.05 [0174] For two-parts formulation 1, parts A and B were combined as a 6:1 w/w (weight ratio) to prepare the compositions I before curing [0175] For two-parts formulation 2, parts A and B were combined as a 1:1 w/w (weight ratio) to prepare the compositions II before curing

[0176] Each composition 1 and 2 were cured at room temperature to yield a silicone rubber syntactic foam comprising a silicone rubber binder and hollow glass beads.

[0177] Other formulations were prepared according to the invention and are described in Table 3. Each formulation was cured to yield a silicone rubber syntactic foam according to the invention. Thermal Conductivity (W/mK) and specific gravity (g/cm3) were measured. Thermal conductivity was measured using a Thermtest Hot Disk TPS (Transient Plane Source) 2500S Tester.

TABLE-US-00003 TABLE 2 Inventive two-parts formulations 3, 4 & 5 precursor of a silicone rubber syntactic foam. Mix Ratio 1:1 Formulation 3 Formulation 4 Formulation 5 by weight (Invention) (Invention) (Invention) Part A Organopolysiloxane A2 89.09% 89.09% 89.09% Hollow glass beads D2 9.09% 9.09% 9.09% Catalyst C-MB 1.82% 1.82% 1.82% Total 100.00% 100.00% 100.00% Part B Organopolysiloxane A2 80.627% 78.124% 74.097% Hollow glass beads D2 9.091% 9.091% 9.091% Organopolysiloxane B1 (CE) 8.479% 9.943% 13.640% Reactive diluent E 0.909% 1.818% 1.818% Organopolysiloxane B2 (XL) 0.756% 0.886% 1.216% Cure rate controller G3-MB 0.138% 0.138% 0.138% Total 100.000% 100.000% 100.000% (H as SiH)/Vinyl Molar Ratio 0.72 0.72 1.00 Form when cured Sticky Gel Sticky Gel Gel/Elastomer Thermal Conductivity 0.17 0.18 0.18 W/mK Specific Gravity of the syntactic 0.87 0.87 0.87 foam ASTM D 792, 23? C.