Silicone elastomer compositions
There is provided curable silicone elastomer compositions having enhanced adhesive properties with respect to a wide variety of substrates. The curable silicone elastomer compositions described herein are provided with a phenylmethylpolysiloxane based additive which comprises at least one, alternatively at least two Si—H groups per molecule and at least one, alternatively at least two anhydride functional groups per molecule. Said phenylmethylpolysiloxane based additives provide resulting elastomers with improved heat-humidity stabilization.
1. A curable silicone elastomer composition that can achieve adhesion on plastic/thermoplastic/resin material substrates, the curable silicone elastomer composition comprising:
(A) one or more organopolysiloxanes containing at least 2 alkenyl and/or alkynyl groups per molecule and having a viscosity in a range of 1,000 to 500,000 mPa·s at 25° C.;
(B) a curing agent comprising
(B)(i) an organic peroxide radical initiator; or
(B)(ii) a hydrosilylation cure catalyst package comprising a hydrosilylation catalyst and an organosilicon compound having at least 2 Si—H groups per molecule, optionally at least 3 Si—H groups per molecule;
(C) at least one reinforcing filler and optionally one or more non-reinforcing fillers; and
(D) an organopolysiloxane based additive which comprises at least one Si—H group per molecule, optionally at least two Si—H groups per molecule and which comprises at least two anhydride functional groups per molecule,
wherein the organopolysiloxane based additive (D) is of the following formula
[(XR 3 SiO) a (HR 3 SiO) m (SiR 3 O)]—O—Y—[(SiR 3 O)(OSiR 3 H) m (OSiR 3 X) a ]
wherein, repeating units in [ ] brackets have a cyclic siloxane structure with the silicon atom in (SiR 3 O) connecting the cyclic siloxane structure to the rest of the molecule, each R 3 group is an alkyl group containing from 1 to 6 carbons, each X is an anhydride containing group, m is an integer of at least 1, optionally at least 2, a is an integer of at least 1; Y is a linear siloxane group of the structure (SiPhR 3 O) n or (SiPh 2 O) n ; Ph is a phenyl group and n is an integer of from 2 to 20.
2. The curable silicone elastomer composition in accordance with claim 1 , wherein m is 2, a is 1, and the average value of n is between 4 and 10.
3. The curable silicone elastomer composition in accordance with claim 1 , wherein the organopolysiloxane based additive (D) is added to the composition in an amount of from 0.5 to 5% by weight of the total composition.
4. The curable silicone elastomer composition in accordance with claim 1 , wherein the composition comprises a cure inhibitor.
5. The curable silicone elastomer composition in accordance with claim 1 , stored before use in at least 2 separate parts.
6. A process for preparing an article or a composite part of an article, the process comprising:
a) forming a mixture of the curable silicone elastomer composition according to claim 1 ;
b) applying the mixture onto a surface of a substrate; and
c) curing the mixture at a temperature of from 80 to 250° C.
7. The process in accordance with claim 6 , wherein the substrate is a polycarbonate.
8. An article containing a silicone elastomer cured from the curable silicone elastomer composition according to claim 1 .
9. The article in accordance with claim 8 , wherein the silicone elastomer is adhered to a plastic substrate.
10. The article in accordance with claim 8 , wherein the silicone elastomer is adhered to a thermoplastic substrate, an organic resin substrate, or a thermoplastic and organic resin substrate.
11. The article in accordance with claim 8 , selected from housings with a silicone seal or gasket, plugs and connectors, components of sensors, membranes, diaphragms, climate venting components, personal electronic equipment, mobile phone cover seals, mobile phone accessories, precision electronic equipment, electrical switches and switch covers, watches and wristbands, or wearable electronic devices.
12. A composite part comprising a silicone elastomer cured from the curable silicone elastomer composition according to claim 1 on a plastic/thermoplastic/resin material substrate, optionally on a polycarbonate material substrate.
13. The composite part in accordance with claim 12 , selected from housings with a silicone seal or gasket, plugs and connectors, components of sensors, membranes, diaphragms, climate venting components, personal electronic equipment, mobile phone cover seals, mobile phone accessories, electronic equipment, electrical switches and switch covers, watches and wristbands, wearable apparatus and/or wearable electronic devices, parts of mobile phones, mobile telecommunications equipment, gaming machines, clocks, image receivers, DVD equipment, MD-media device and mini-disk equipment, CD equipment, microwave ovens, refrigerators, electric rice cookers, cathode ray TVs, thin displays of liquid crystal TVs and plasma TVs, home appliances, copying machines, printers, facsimile machines, and office automation equipment, connector seals, spark plug caps, and automobile components.