Adhesives having improved chemical resistance and curable silicone compositions for preparing the adhesives Number:7,521,125 from the United States Patent and Trademark Office (PTO) owispatent This invention relates to a composition that can be cured to form an adhesive. The adhesive is useful in the electronics industry. The composition is prepared by mixing components including: (I) a polyorganosiloxane having an average of at least two terminally-unsaturated organic groups per molecule, (II) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, (III) a hydrosilylation catalyst, (IV) a fluoroorganosilicone having at least one functional group reactive with component (I), component (II), or both, (V) an unsaturated ester-functional compound, and (VI) an adhesion promoter. The composition may also include one or more optional components selected from (VII) a void reducing agent, (VIII) a pigment, (IX) a filler, (X) a cure modifier, (XI) a rheology modifier, and (XII) a spacer.<H compositions, resistance, Adhesives, havin, 7521125.html, Patent, pto, 7521125

Title: Adhesives having improved chemical resistance and curable silicone compositions for preparing the adhesives

Abstract: This invention relates to a composition that can be cured to form an adhesive. The adhesive is useful in the electronics industry. The composition is prepared by mixing components including: (I) a polyorganosiloxane having an average of at least two terminally-unsaturated organic groups per molecule, (II) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, (III) a hydrosilylation catalyst, (IV) a fluoroorganosilicone having at least one functional group reactive with component (I), component (II), or both, (V) an unsaturated ester-functional compound, and (VI) an adhesion promoter. The composition may also include one or more optional components selected from (VII) a void reducing agent, (VIII) a pigment, (IX) a filler, (X) a cure modifier, (XI) a rheology modifier, and (XII) a spacer.

Patent Number: 7,521,125 Issued on 04/21/2009 to Ahn, et al.

Inventors: Ahn; Dongchan (Midland, MI), Rolley; Patricia Ann (Midland, MI)
Assignee: Dow Corning Corporation (Midland, MI)

Appl. No.: 11/181,301

Filed: July 14, 2005

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
10641758	Aug., 2003	7045586

Current U.S. Class: 428/447 ; 427/387; 525/478; 528/15; 528/26; 528/31; 528/32; 528/42

Current International Class: C08G 77/24 (20060101)

Field of Search: 528/15,26,31,32,42 427/387 428/447 525/478

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Primary Examiner: Moore; Margaret G
Attorney, Agent or Firm: Brown; Catherine U.

Parent Case Text

CROSS REFERENCE

This application is a continuation in part of U.S. patent application Ser. No. 10/641,758, filed on 14 Aug. 2003 now U.S. Pat. No. 7,045,586 and claims priority thereto under 35 U.S.C. .sctn. 120 and 35 U.S.C. .sctn.365(c). U.S. patent application Ser. No. 10/641,758 is hereby incorporated by reference.

Claims

The invention claimed is:

1. A method comprising: (1) applying a composition to a substrate, and (2) curing the composition; where the composition is prepared by mixing components comprising (I) a polyorganosiloxane having an average of at least two unsaturated organic groups per molecule, where component (I) is free of fluorine atoms; (II) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, where component (II) is free of fluorine atoms; (III) a hydrosilylation catalyst; (IV) a fluoroorganosilicone having at least one functional group reactive with component (I), component (II), or both; (V) an unsaturated ester-functional compound comprising ##STR00002## v) a combination thereof; where in formula i), each R.sup.18 is independently a hydrogen atom, a monovalent hydrocarbon group of 1 to 4 carbon atoms, or CF.sub.3, each R.sup.19 is independently a divalent organic group of 1 to 20 carbon atoms, each R.sup.20 is independently a hydrogen atom or a monovalent hydrocarbon group of 1 to 20 carbon atoms, in formula ii), n has an average value of 0 to 2 and m=4-n, each R.sup.21 is independently a hydroxyl group, or CF.sup.3, each R.sup.22 is independently a hydrogen atom, a monovalent hydrocarbon group of 1 to 4 carbon atoms, or CF.sup.3, each R.sup.23 is independently a hydrogen atom or a monovalent hydrocarbon group of 1 to 20 carbon atoms, in formula iii), each R.sup.24 is independently a fluoroalkyl group, an epoxy functional group, or a polyether group, each R.sup.25 is independently anoxygen-bridged monovalent organic group or a carbon-bridged carbonyl group, with the proviso that at least one of R.sup.24 or R.sup.25 is unsaturated, in formula iv), each R.sup.26 is independently a monovalent organic group or a hydrogen atom, with the proviso that at least one R.sup.26 is an aliphatically unsaturated monovalent organic group or a hydrogen atom, and each R.sup.27 is independently an oxygen atom or a divalent organic group; and (VI) an adhesion promoter.

2. The method of claim 1, where the substrate comprises an epoxy, a polycarbonate, a poly(butylene terephthalate) resin, a polyamide resin, a blend of polyamide resin with syndiotactic polystyrene, an acrylonitrile-butadiene-styrene, a styrene-modified poly(phenylene oxide), a poly(phenylene sulfide), a vinyl ester, a polyphthalamide, a polyimide, silicon, aluminum, a stainless steel alloy, titanium, copper, nickel, silver, gold, or combinations thereof.

3. The method of claim 1, where the substrate comprises a metal.

4. The method of claim 1, where component (I) comprises a polyorganosiloxane of the formula: (a) R.sup.1.sub.3SiO(R.sup.1.sub.2SiO).sub..alpha.(R.sup.1R.sup.2SiO).sub..be- ta.SiR.sup.1.sub.3, (b) R.sup.3.sub.2R.sup.4SiO(R.sup.3.sub.2SiO).sub..chi.(R.sup.3R.sup.4SiO).su- b..delta.SiR.sup.3.sub.2R.sup.4, or (c) a combination thereof, where .alpha. has an average value of 0 to 2000, .beta. has an average value of 2 to 2000, each R.sup.1 is independently a monovalent organic group, each R.sup.2 is independently an unsaturated monovalent organic group, .chi. has an average value of 0 to 2000, .delta. has an average value of 0 to 2000, each R.sup.3 is independently a monovalent organic group, and each R.sup.4 is independently an unsaturated monovalent organic group.

5. The method of claim 1, where component (I) comprises an MQ resin consisting essentially of R.sup.5.sub.3SiO.sub.1/2 units and SiO.sub.4/2 units, a TD resin consisting essentially of R.sup.5SiO.sub.3/2 units and R.sup.5.sub.2SiO.sub.2/2 units, an MT resin consisting essentially of R.sup.5.sub.3SiO.sub.1/2 units and R.sup.5SiO.sub.3/2 units, an MTD resin consisting essentially of R.sup.5.sub.3SiO.sub.1/2 units, R.sup.5SiO.sub.3/2 units, and R.sup.5.sub.2SiO.sub.2/2 units, or a combination thereof, where each R.sup.5 is a monovalent organic group of 1 to 20 carbon atoms, and the resin contains an average of 3 to 30 mole percent of unsaturated organic groups.

6. The method of claim 1, where component (II) comprises siloxane units selected from HR.sup.6.sub.2SiO.sub.1/2, R.sup.6.sub.3SiO.sub.1/2, HR.sup.6SiO.sub.2/2, R.sup.6.sub.2SiO.sub.2/2, R.sup.6SiO.sub.3/2, SiO.sub.4/2, or combinations thereof; where each R.sup.6 is independently selected from monovalent organic groups free of aliphatic unsaturation.

7. The method of claim 1, where component (II) comprises a compound of the formula: (a) R.sup.7.sub.3SiO(R.sup.7.sub.2SiO).sub..epsilon.(R.sup.7HSiO).sub..phi.Si- R.sup.7.sub.3, or (b) R.sup.8.sub.2HSiO(R.sup.8.sub.2SiO).sub..gamma.(R.sup.8HSiO).sub..eta.SiR- .sup.8.sub.2H, (c) a combination thereof, where .epsilon. has an average value of 0 to 2000, .phi. has an average value of 2 to 2000, each R.sup.7 is independently a monovalent organic group free of aliphatic unsaturation, .gamma. has an average value of 0 to 2000, .eta. has an average value of 0 to 2000, and each R.sup.8 is independently a monovalent organic group free of aliphatic unsaturation.

8. The method of claim 1, where component (III) comprises a platinum metal, a rhodium metal, or an organometallic compound.

9. The method of claim 1, where component (IV) comprises a compound of the formula: (a) R.sup.9.sub.3SiO(R.sup.9.sub.2SiO).sub..tau.(R.sup.9R.sup.10SiO).sub..phi- .SiR.sup.9.sub.3, (b) R.sup.11.sub.2R.sup.12SiO(R.sup.11.sub.2SiO).sub..kappa.(R.sup.11R.sup.12- SiO).sub..lamda.SiR.sup.11.sub.2R.sup.12, (c) F.sub.3C(CF.sub.2).sub..nu.R.sup.13--Si--[O--Si(R.sup.14).sub.2(R.sup.15)- ].sub.3, (d) a resinous or branched structure consisting essentially of R.sup.15R.sup.14.sub.2SiO.sub.1/2 units, CF.sub.3(CF.sub.2).sub..nu.R.sup.13SiO.sub.3/2 units, and optionally SiO.sub.4/2 units, or (e) a combination thereof; where .xi. has an average value of 0 to 2000, .phi. has an average value of 1 to 500, each R.sup.9 is independently a hydrogen atom or a monovalent organic group, with the proviso that at least one R.sup.9 is a hydrogen atom or an unsaturated monovalent organic group; each R.sup.10 is independently a fluoro-functional organic group; .kappa. has an average value of 0 to 2000; .lamda. has an average value of 0 to 500; each R.sup.11 is independently a hydrogen atom or a monovalent organic group, with the proviso that at least one R.sup.11 is a hydrogen atom or an unsaturated monovalent organic group; each R.sup.12 is independently a fluoro-functional organic group; each R.sup.13 is independently a divalent organic group; each R.sup.14 is independently a monovalent hydrocarbon group free of aliphatic unsaturation; .nu. is 0 to 10; and each R.sup.15 is independently a hydrogen atom or an unsaturated monovalent organic group.

10. The method of claim 1, where component (VI) comprises a transition metal chelate, an alkoxysilane, a combination of an alkoxysilane and a hydroxy-functional polyorganosiloxane, or a combination thereof.

11. The method of claim 1, where component (VI) comprises an unsaturated alkoxysilane, an epoxy-functional alkoxysilane, an epoxy-functional siloxane, or a combination thereof.

12. The method of claim 1, where component (VI) comprises an alkoxysilane of the formula R.sup.28 .sub..mu.Si(OR.sup.29).sub.(4-.mu.), where .mu. is 1, 2, or 3, each R.sup.28 is independently a monovalent organic group, with the proviso that at least one R.sup.28 is an unsaturated organic group or an epoxy-functional group, and each R.sup.29 is independently an unsubstituted, saturated hydrocarbon group of at least 1 carbon atom.

13. The method of claim 1, where the composition further comprises (VII) a void reducing agent, (VIII) a pigment, (IX) a filler, (X) a cure modifier, (XI) a rheology modifier, (XII) a spacer, an acid acceptor, an anti-oxidant, a stabilizer, a flame retardant, a flow control additive, a reactive diluent, an anti-settling agent, a silylating agent, a desiccant, a blowing agent, or a combination thereof.

14. The method of claim 1, where the composition has SiH.sub.tot/Vi.sub.tot of 1.05 to 5.0.

15. The method of claim 1, where the method forms a product selected from die attach adhesives, as lid seals, gels and encapsulants.

16. The method of claim 1, where the composition is applied to more than one substrate in step (1).

Description

FIELD OF THE INVENTION

This invention relates to curable silicone compositions and products formed by curing the curable silicone compositions. More particularly, this invention relates to hydrosilylation-curable compositions that cure to form products having improved adhesion and chemical resistance.

BACKGROUND OF THE INVENTION

Plastics containing low surface energy polymers, e.g., blends of Nylon and syndiotactic polystyrene (sPS), are seeing growing acceptance as a replacement for denser, hygroscopic plastics such as polybutyleneterephthalate (PBT) and Nylon as substrates in high performance applications such as those found in the electronics and automotive industries. For example, existing adhesives used in the electronics industry suffer from the drawback of having poor adhesion to substrates containing syndiotactic polystyrene. Therefore, there is a need for developing adhesives having improved adhesion to substrates containing sPS while retaining adhesion to a variety of other organic and inorganic substrates.

Furthermore, polyorganosiloxane elastomer adhesives, such as polydimethylsiloxane-based elastomers, are frequently used in the electronics industry for properties such as their thermal stability and ability to relieve stresses over a broad thermal range. However, these adhesives may suffer from the drawback of poor resistance to some organic chemicals, such as solvents and engine oils. Fluorosilicone elastomers and organic elastomers have been used to improve chemical resistance. However, fluorosilicone elastomers suffer from the drawback of having higher cost than polyorganosiloxane elastomers (that are non-fluorinated). One proposed approach to address this is to combine fluorosilicone elastomers with polyorganosiloxane elastomers. However, proposed approach has generally not been used due to concerns that the fluorosilicone and non-fluorinated organosilicone components would phase separate, resulting in unstable properties. Organic elastomers may suffer from the drawback of having insufficient flexibility or bulk thermal properties. Therefore, there is a need in the electronics industry for adhesives having improved chemical resistance while retaining flexibility and bulk thermal properties.

SUMMARY OF THE INVENTION

This invention relates to a composition prepared by mixing components comprising: (I) a polyorganosiloxane having an average of at least two unsaturated organic groups per molecule, (II) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, (III) a hydrosilylation catalyst, (IV) a fluoroorganosilicone having at least one functional group reactive with component (I), component (II), or both, (V) an unsaturated ester-functional compound, and (VI) an adhesion promoter. Component (I) is free of fluorine atoms. Component (II) is free of fluorine atoms.

DETAILED DESCRIPTION OF THE INVENTION

All amounts, ratios, and percentages are by weight unless otherwise indicated. The following is a list of definitions, as used herein.

DEFINITIONS AND USAGE OF TERMS

"A" and "an" each mean one or more.

"Chemical resistance" means reduced tendency of a silicone elastomer to swell, or degrade, or both, when exposed to solvents and oils.

"Combination" means two or more items put together by any method.

The abbreviation "cP" means centipoise.

The abbreviation "IR" means infrared.

"Pa.s" means Pascal seconds.

The abbreviation "ppm" means parts per million.

"Silicone" and "siloxane" are used interchangeably herein.

This invention relates to a composition prepared by mixing components comprising: (I) a polyorganosiloxane having an average of at least two unsaturated organic groups per molecule, (II) an organohydrogenpolysiloxane having an average of at least two silicon bonded hydrogen atoms per molecule, (III) a hydrosilylation catalyst, (IV) a fluoroorganosilicone having at least one functional group reactive with component (I), component (II), or both, (V) an unsaturated ester-functional compound, and (VI) an adhesion promoter.

Component (I) Polyorganosiloxane

Component (I) is a polyorganosiloxane having an average of at least two unsaturated organic groups per molecule. Component (I) may have a linear, branched, or resinous structure. Component (I) may be a homopolymer or a copolymer. The unsaturated organic groups may be alkenyl groups having from 2 to 12 carbon atoms and are exemplified by, but not limited to, vinyl, allyl, butenyl, and hexenyl. The unsaturated organic groups may be alkynyl groups having 2 to 12 carbon atoms, and are exemplified by, but not limited to, ethynyl, propynyl, and butynyl. Alternatively, the unsaturated organic groups may contain acrylate-functional or methacrylate-functional groups and are exemplified by, but not limited to, acryloyloxyalkyl such as acryloyloxypropyl and methacryloyloxyalkyl such as methacryloyloxypropyl. The unsaturated organic groups in component (I) may be located at terminal, pendant, or both terminal and pendant positions.

The remaining silicon-bonded organic groups in component (I) may be monovalent organic groups free of aliphatic unsaturation. These monovalent organic groups may have 1 to 20 carbon atoms, alternatively 1 to 10 carbon atoms, and are exemplified by, but not limited to alkyl such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl; cycloalkyl such as cyclohexyl; aryl such as phenyl, tolyl, xylyl, benzyl, and 2-phenylethyl; and cyano-functional groups such as cyanoalkyl groups exemplified by cyanoethyl and cyanopropyl. Component (I) is free of fluorine atoms.

The viscosity of component (I) is not specifically restricted, however, component (I) may have a viscosity of 0.05 to 500 Pa.s at 25.degree. C., alternatively 0.1 to 200 Pa.s at 25.degree. C. Component (I) is added to the composition in an amount of 100 weight parts. Component (I) may comprise a polyorganosiloxane of the formula (a) R.sup.1.sub.3SiO(R.sup.1.sub.2SiO).sub..alpha.(R.sup.1R.sup.2SiO).sub..be- ta.SiR.sup.1.sub.3, (b) R.sup.3.sub.2R.sup.4SiO(R.sup.3.sub.2SiO).sub..chi.(R.sup.3R.sup.4SiO).su- b..delta.SiR.sup.3.sub.2R.sup.4, or (c) a combination thereof.

In formula (a), .alpha. has an average value of 0 to 2000, and .beta. has an average value of 2 to 2000. Each R.sup.1 is independently a monovalent organic group. Suitable monovalent organic groups include, but are not limited to, acrylic functional groups such as acryloyloxypropyl and methacryloyloxypropyl; alkyl groups such as methyl, ethyl, propyl, and butyl; alkenyl groups such as vinyl, allyl, and butenyl; alkynyl groups such as ethynyl and propynyl; aromatic groups such as phenyl, tolyl, and xylyl; and cyanoalkyl groups such as cyanoethyl and cyanopropyl. Each R.sup.2 is independently an unsaturated monovalent organic group. R.sup.2 is exemplified by alkenyl groups such as vinyl, allyl, and butenyl and alkynyl groups such as ethynyl and propynyl, and acrylic functional groups such as acryloyloxypropyl and methacryloyloxypropyl.

In formula (b), .chi. has an average value of 0 to 2000, and .delta. has an average value of 0 to 2000. Each R.sup.3 is independently a monovalent organic group. Suitable monovalent organic groups include, but are not limited to, acrylic functional groups such as acryloyloxypropyl and methacryloyloxypropyl; alkyl groups such as methyl, ethyl, propyl, and butyl; alkenyl groups such as vinyl, allyl, and butenyl; alkynyl groups such as ethynyl and propynyl; aromatic groups such as phenyl, tolyl, and xylyl; and cyanoalkyl groups such as cyanoethyl and cyanopropyl. Each R.sup.4 is independently an unsaturated organic hydrocarbon group. R.sup.4 is exemplified by alkenyl groups such as vinyl, allyl, and butenyl; alkynyl groups such as ethynyl and propynyl; and acrylic functional groups such as acryloyloxypropyl and methacryloyloxypropyl.

Component (I) may comprise polydiorganosiloxanes such as i) dimethylvinylsiloxy-terminated polydimethylsiloxane, ii) dimethylvinylsiloxy-terminated poly(dimethylsiloxane/methylvinylsiloxane), iii) dimethylvinylsiloxy-terminated polymethylvinylsiloxane, iv) trimethylsiloxy-terminated poly(dimethylsiloxane/methylvinylsiloxane), v) trimethylsiloxy-terminated polymethylvinylsiloxane, vi) dimethylvinylsiloxy-terminated poly(dimethylsiloxane/methylphenylsiloxane), vii) dimethylvinylsiloxy-terminated poly(dimethylsiloxane/diphenylsiloxane), viii) phenyl,methyl,vinyl-siloxy-terminated polydimethylsiloxane, ix) dimethyl-acryloyloxypropyl-siloxy-terminated polydimethylsiloxane, x) dimethyl-methacryloyloxypropyl-siloxy-terminated polydimethylsiloxane, xi) dimethylhexenylsiloxy-terminated polydimethylsiloxane, xii) dimethylhexenylsiloxy-terminated poly(dimethylsiloxane/methylhexenylsiloxane), xiii) dimethylhexenylsiloxy-terminated polymethylhexenylsiloxane, xiv) trimethylsiloxy-terminated poly(dimethylsiloxane/methylhexenylsiloxane), xv) dimethylvinylsiloxy-terminated poly(dimethylsiloxane/methylcyanopropylsiloxane), and xvi) combinations thereof.

Methods of preparing polydiorganosiloxanes suitable for use as component (I), such as hydrolysis and condensation of the corresponding organohalosilanes or equilibration of cyclic polydiorganosiloxanes, are well known in the art.

Component (I) may comprise resins such as an MQ resin consisting essentially of R.sup.5.sub.3SiO.sub.1/2 units and SiO.sub.4/2 units, a TD resin consisting essentially of R.sup.5SiO.sub.3/2 units and R.sup.5.sub.2SiO.sub.2/2 units, an MT resin consisting essentially of R.sup.5.sub.3SiO.sub.1/2 units and R.sup.5SiO.sub.3/2 units, an MTD resin consisting essentially of R.sup.5.sub.3SiO.sub.1/2 units, R.sup.5SiO.sub.3/2 units, and R.sup.5.sub.2SiO.sub.2/2 units, or a combination thereof.

Each R.sup.5 is a monovalent organic group. The monovalent organic groups represented by R.sup.5 may have 1 to 20 carbon atoms, alternatively 1 to 10 carbon atoms. Examples of monovalent organic groups include, but are not limited to, acrylate functional groups such as acryloxyalkyl groups, methacrylate functional groups such as methacryloxyalkyl groups, cyano-functional groups, and monovalent hydrocarbon groups. Monovalent hydrocarbon groups include, but are not limited to, alkyl such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl; cycloalkyl such as cyclohexyl; alkenyl such as vinyl, allyl, butenyl, and hexenyl; alkynyl such as ethynyl, propynyl, and butynyl; and aryl such as phenyl, tolyl, xylyl, benzyl, and 2-phenylethyl. Cyano-functional groups include, but are not limited to cyanoalkyl groups such as cyanoethyl and cyanopropyl.

The resin may contain an average of 3 to 30 mole percent of unsaturated organic groups. The unsaturated organic groups may be alkenyl groups, alkynyl groups, acrylate-functional groups, methacrylate-functional groups, or combinations thereof. The mole percent of unsaturated organic groups in the resin is the ratio of the number of moles of unsaturated group-containing siloxane units in the resin to the total number of moles of siloxane units in the resin, multiplied by 100.

Methods of preparing resins are well known in the art. For example, resin may be prepared by treating a resin copolymer produced by the silica hydrosol capping process of Daudt et al. with at least an alkenyl-containing endblocking reagent. The method of Daudt et al., is disclosed in U.S. Pat. No. 2,676,182.

Briefly stated, the method of Daudt et al. involves reacting a silica hydrosol under acidic conditions with a hydrolyzable triorganosilane such as trimethylchlorosilane, a siloxane such as hexamethyldisiloxane, or mixtures thereof, and recovering a copolymer having M and Q units. The resulting copolymers generally contain from 2 to 5 percent by weight of hydroxyl groups.

The resin, which typically contains less than 2 percent by weight of silicon-bonded hydroxyl groups, may be prepared by reacting the product of Daudt et al. with an unsaturated organic group-containing endblocking agent and an endblocking agent free of aliphatic unsaturation, in an amount sufficient to provide from 3 to 30 mole percent of unsaturated organic groups in the final product. Examples of endblocking agents include, but are not limited to, silazanes, siloxanes, and silanes. Suitable endblocking agents are known in the art and exemplified in U.S. Pat. Nos. 4,584,355; 4,591,622; and 4,585,836. A single endblocking agent or a mixture of such agents may be used to prepare the resin.

Component (I) can be a single polyorganosiloxane or a combination comprising two or more polyorganosiloxanes that differ in at least one of the following properties: structure, viscosity, average molecular weight, siloxane units, and sequence.

Component (II) Organohydrogenpolysiloxane

Component (II) is an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule. Component (II) can be can be a homopolymer or a copolymer. Component (II) can have a linear, branched, cyclic, or resinous structure. The silicon-bonded hydrogen atoms in the component (II) can be located at terminal, pendant, or at both terminal and pendant positions. Component (II) is free of fluorine atoms.

Component (II) can comprise siloxane units including, but not limited to, HR.sup.6.sub.2SiO.sub.1/2, R.sup.6.sub.3SiO.sub.1/2, HR.sup.6SiO.sub.2/2, R.sup.6.sub.2SiO.sub.2/2, R.sup.6SiO.sub.3/2, and SiO.sub.4/2 units. In the preceding formulae, each R.sup.6 is independently selected from monovalent organic groups free of aliphatic unsaturation.

Component (II) may comprise a compound of the formula (a) R.sup.7.sub.3SiO(R.sup.7.sub.2SiO).sub..epsilon.(R.sup.7HSiO).sub..phi.Si- R.sup.7.sub.3, or R.sup.8.sub.2HSiO(R.sup.8.sub.2SiO).sub..gamma.R.sup.8HSiO).sub..eta.SiR.- sup.8.sub.2H, (c) a combination thereof.

In formula (a), .epsilon. has an average value of 0 to 2000, and .phi. has an average value of 2 to 2000. Each R.sup.7 is independently a monovalent organic group free of aliphatic unsaturation. Suitable monovalent organic groups free of aliphatic unsaturation include alkyl groups such as methyl, ethyl, propyl, and butyl; aromatic groups such as phenyl, tolyl, and xylyl; and cyano-functional groups exemplified by cyanoalkyl groups such as cyanoethyl and cyanopropyl.

In formula (b), .gamma. has an average value of 0 to 2000, and .eta. has an average value of 0 to 2000. Each R.sup.8 is independently a monovalent organic group free of aliphatic unsaturation. Suitable monovalent organic groups free of aliphatic unsaturation include alkyl groups such as methyl, ethyl, propyl, and butyl; aromatic groups such as phenyl, tolyl, and xylyl; and cyano-functional groups exemplified by cyanoalkyl groups such as cyanoethyl and cyanopropyl.

Component (II) is exemplified by i) dimethylhydrogensiloxy-terminated polydimethylsiloxane, ii) dimethylhydrogensiloxy-terminated poly(dimethylsiloxane/methylhydrogensiloxane), iii) dimethylhydrogensiloxy-terminated polymethylhydrogensiloxane, iv) trimethylsiloxy-terminated poly(dimethylsiloxane/methylhydrogensiloxane), v) trimethylsiloxy-terminated polymethylhydrogensiloxane, vi) a resin consisting essentially of H(CH.sub.3).sub.2SiO.sub.1/2 units and SiO.sub.4/2 units, and vii) combinations thereof.

Component (II) can be a combination of two or more organohydrogenpolysiloxanes that differ in at least one of the following properties: structure, average molecular weight, viscosity, siloxane units, and sequence.

Methods of preparing linear, branched, and cyclic organohydrogenpolysiloxanes suitable for use as component (II), such as hydrolysis and condensation of organohalosilanes, are well known in the art. Methods of preparing organohydrogenpolysiloxane resins suitable for use as component (II) are also well known as exemplified in U.S. Pat. Nos. 5,310,843; 4,370,358; and 4,707,531.

The molar ratio of silicon-bonded hydrogen atoms in component (B) to aliphatically unsaturated groups in component (A) (SiH.sub.B/Vi.sub.A) is not critical.

Component (III) Hydrosilylation Catalyst

Component (III) is a hydrosilylation catalyst. Component (III) is added to the composition in an amount of 0.1 to 1000 ppm of platinum group metal, alternatively 1 to 500 ppm, alternatively 2 to 200, alternatively 5 to 150 ppm, based on the weight of the composition. Suitable hydrosilylation catalysts are known in the art and commercially available. Component (III) may comprise a platinum group metal selected from platinum, rhodium, ruthenium, palladium, osmium or iridium metal or organometallic compound thereof, or a combination thereof. Component (III) is exemplified by compounds such as chloroplatinic acid, chloroplatinic acid hexahydrate, platinum dichloride, and complexes of said compounds with low molecular weight organopolysiloxanes or platinum compounds microencapsulated in a matrix or coreshell type structure. Complexes of platinum with low molecular weight organopolysiloxanes include 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane complexes with platinum. These complexes may be microencapsulated in a resin matrix.

Suitable hydrosilylation catalysts for component (III) are described in, for example, U.S. Pat. Nos. 3,159,601; 3,220,972; 3,296,291; 3,419,593; 3,516,946; 3,814,730; 3,989,668; 4,784,879; 5,036,117; and 5,175,325 and EP 0 347 895 B. Microencapsulated hydrosilylation catalysts and methods of preparing them are known in the art, as exemplified in U.S. Pat. No. 4,766,176 and the references cited therein; and U.S. Pat. No. 5,017,654.

Component (IV) Fluoroorganosilicone

Component (IV) is a fluoroorganosilicone having at least one functional group reactive with component (I), component (II), or both. The viscosity of component (IV) is not specifically restricted, however, component (IV) may have a viscosity of 0.0001 to 500 Pa.s at 25.degree. C.

Component (IV) may comprise a compound of the formula: (a) R.sup.9.sub.3SiO(R.sup.9.sub.2SiO).sub..tau.(R.sup.9R.sup.10SiO).sub..phi- .SiR.sup.9.sub.3, (b) R.sup.11.sub.2R.sup.12SiO(R.sup.11.sub.2SiO).sub..kappa.(R.sup.11R.sup.12- SiO).sub..lamda.SiR.sup.11.sub.2R.sup.12, (c) F.sub.3C(CF.sub.2).sub..nu.R.sup.13--Si--[O--Si(R.sup.14).sub.2(R.sup.15)- ].sub.3, (d) a resinous or branched structure consisting essentially of R.sup.15R.sup.14.sub.2SiO.sub.1/2 units, CF.sub.3(CF.sub.2).sub..nu.R.sup.13SiO.sub.3/2 units, and optionally SiO.sub.4/2 units, or (e) a combination thereof.

In formula (a) .tau. has an average value of 0 to 2000, and .phi. has an average value of 1 to 500. Each R.sup.9 is independently a hydrogen atom or a monovalent organic group. Suitable monovalent organic groups include monovalent hydrocarbon groups that are free of aliphatic unsaturation such as alkyl groups such as methyl, ethyl, propyl, and butyl; aromatic groups such as phenyl, tolyl, and xylyl; and cyano-functional groups exemplified by cyanoalkyl groups such as cyanoethyl and cyanopropyl. Suitable monovalent organic groups also include unsaturated monovalent organic groups exemplified by acrylate functional groups; methacrylate functional groups; alkenyl groups such as vinyl, allyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl. In formula (a) at least one R.sup.9 is a hydrogen atom or an unsaturated monovalent organic group. Each R.sup.10 is independently a fluoro-functional organic group. Suitable fluoro-functional organic groups include, but are not limited to, fluorinated alkyl groups such as 3,3,3-trifluoropropyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, and 6,6,6,5,5,4,4,3,3-nonafluorohexyl.

In formula (b) .kappa. has an average value of 0 to 2000, and .lamda. has an average value of 0 to 500. Each R.sup.11 is independently a hydrogen atom or a monovalent organic group. Suitable monovalent organic groups include cyano-functional groups exemplified by cyanoalkyl groups such as cyanoethyl and cyanopropyl; and monovalent hydrocarbon groups free of aliphatic unsaturation, exemplified by alkyl groups such as methyl, ethyl, propyl, and butyl; and aromatic groups such as phenyl, tolyl, and xylyl. Suitable monovalent organic groups also include unsaturated monovalent organic groups exemplified by acrylate functional groups; methacrylate functional groups; alkenyl groups such as vinyl, allyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl. In formula (b) at least one R.sup.11 is a hydrogen atom or an unsaturated monovalent organic group. Each R.sup.12 is independently a fluoro-functional organic group. Suitable fluoro-functional organic groups include fluorinated alkyl groups such as 3,3,3-trifluoropropyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, and 6,6,6,5,5,4,4,3,3-nonafluorohexyl.

In formulae (c) and (d), .nu. is 0 to 10. Each R.sup.13 is independently a divalent organic group such as a divalent hydrocarbon group. Suitable divalent organic groups for R.sup.13 may have at least 2 carbon atoms, alternatively, 2 to 20 carbon atoms, alternatively 2 to 10 carbon atoms. Examples of suitable divalent hydrocarbon groups for R.sup.13 include alkylene groups such as methylene, ethylene, propylene, and butylene. Each R.sup.14 is independently a monovalent hydrocarbon group free of aliphatic unsaturation. R.sup.14 is exemplified by alkyl such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl; cycloalkyl such as cyclohexyl; and aryl such as phenyl, tolyl, xylyl, benzyl, and 2-phenylethyl. Each R.sup.15 is independently a hydrogen atom or an aliphatically unsaturated hydrocarbon group exemplified by alkenyl such as vinyl, allyl, butenyl, and hexenyl; and alkynyl such as ethynyl, propynyl, and butynyl. If one R.sup.15 is an aliphatically unsaturated hydrocarbon group, then all R.sup.15 in the molecule may be the same or different aliphatically unsaturated hydrocarbon group. If one R.sup.15 in a molecule is a hydrogen atom, then all R.sup.15 may be hydrogen atoms.

Component (IV) is exemplified by i) dimethylvinylsiloxy-terminated polymethyl3,3,3-trifluoropropyl siloxane, ii) dimethylvinylsiloxy-terminated poly(methylhydrogensiloxane/methyl-6,6,6,5,5,4,4,3,3-nonafluorohexylsilox- ane), iii) trimethylsiloxy-terminated poly(methylhydrogensiloxane/methyl-6,6,6,5,5,4,4,3,3-nonafluorohexylsilox- ane), and iv) combinations thereof.

Alternatively, compoinent (IV) is exemplified by i) dimethylvinylsiloxy-terminated polymethyl3,3,3-trifluoropropyl siloxane, ii) dimethylvinylsiloxy-terminated poly(methylhydrogensiloxane/methyl-6,6,6,5,5,4,4,3,3-nonafluorohexylsilox- ane), iii) trimethylsiloxy-terminated poly(methylhydrogensiloxane/methyl-6,6,6,5,5,4,4,3,3-nonafluorohexylsilox- ane), iv) trimethylsiloxy-terminated poly(methylhydrogensiloxane/methyl-3,3,3-trifluoropropylmethyl-6,6,6,5,5,- 4,4,3,3-nonafluorohexylsiloxane), v) trimethylsiloxy-terminated poly(methylvinylsiloxane/methyl-6,6,6,5,5,4,4,3,3-nonafluorohexylsiloxane- ) or vi) combinations thereof.

Component (IV) is added to the composition in an amount of 0.01 to 100 parts by weight based on the weight of component (I). As the optimal overall composition depends upon the specific properties desired such as viscosity, modulus, or cure speed, the optimal level of component (IV) may vary accordingly. Without wishing to be bound by theory, it is thought that the halogenated portion of component (IV) migrates to the surface of the composition when cured. It is thought that sufficient chemical resistance for many applications can be obtained without adding a higher amount of component (IV), which would dramatically increase the cost of the composition. Without wishing to be bound by theory, it is thought that component (IV) also facilitates migration of component (V) to the surface of the composition and to other interfaces, further increasing chemical resistance and improving adhesion. Component (IV) may be a combination of two or more fluoroorganosilicones that differ in at least one of the following properties: structure, average molecular weight, viscosity, siloxane units, and sequence.

Fluoroorganosilicones suitable for use as component (IV) are known in the art. Fluoroorganosilicones may be prepared by those methods disclosed above for components (I) and (II), by varying appropriate starting materials. One skilled in the art would be able to manufacture suitable fluoroorganosilicones for component (IV) without undue experimentation.

Component (V) Unsaturated Ester-Functional Compound

Component (V) is an unsaturated ester-functional compound, i.e., an organic compound having at least one ester group per molecule and at least one unsaturated group per molecule capable of undergoing hydrosilylation. Component (V) may comprise:

##STR00001## vi) a combination thereof.

In formula i), each R.sup.16 is independently a hydrogen atom, a monovalent hydrocarbon group of 1 to 4 carbon atoms, or CF.sub.3. Examples of monovalent hydrocarbon groups for R.sup.16 include alkyl groups such as methyl, ethyl, propyl, and butyl. Each R.sup.17 is independently a hydrogen atom, a monovalent organic group, with the proviso that not all R.sup.17 are hydrogen atoms, or a metal ion. Examples of monovalent organic groups for R.sup.17 include monovalent hydrocarbon groups, fluoroalkyl groups, epoxy functional groups, and polyether groups. Examples of monovalent hydrocarbon groups include, but are not limited to, alkyl such as methyl, ethyl, propyl, pentyl, octyl, undecyl, dodecyl, and octadecyl; cycloalkyl such as cyclohexyl; alkenyl such as vinyl, allyl, butenyl, and hexenyl; alkynyl such as ethynyl, propynyl, and butynyl; and aryl such as phenyl, tolyl, xylyl, benzyl, and 2-phenylethyl. Examples of epoxy-functional groups for R.sup.17 include 3-glycidoxypropyl. Examples of fluoroalkyl groups for R.sup.17 include but are not limited to --(CH.sub.2).sub.x(CF.sub.2).sub.yCF.sub.3 where x has an average value of 0 to 20 and y has an average value of 0 to 20, branched fluoroalkyl groups such as perfluoro t-butyl, and cyclic fluoroalkyl groups such as perfluorocyclohexyl, and fluoroaryl groups such as perfluorophenyl. Examples of polyether groups for R.sup.17 include, but are not limited to, --(CH.sub.2CH.sub.2O).sub.zCH.sub.2CH.sub.3, --(CH(CH.sub.3)CH.sub.2O).sub.zCH(CH.sub.3)CH.sub.3, --(CH2CH.sub.2O).sub.zCH.sub.2CH.dbd.CH.sub.2, --(CH(CH.sub.3)CH.sub.2O).sub.zCH.sub.2CH.dbd.CH.sub.2, --(CH.sub.2CH.sub.2CH.sub.2CH.sub.2O).sub.zCH.sub.2CH.sub.3, --(CH.sub.2CH.sub.2CH.sub.2CH.sub.2O).sub.zCH.dbd.CH.sub.2, --(CH.sub.2CH.sub.2O).sub.zCH.sub.2CH.sub.2OH, --(CH(CH.sub.3)CH.sub.2O).sub.zCH(CH.sub.3)CH.sub.2--OH, --(CH.sub.2CH.sub.2O).sub.zCH.sub.2CH.sub.2OCH3, and --(CH(CH.sub.3)CH.sub.2O).sub.zCH(CH.sub.3)CH.sub.2--OCH.sub.3 where z has an average value of 1 to 20, and cyclic ethers such as tetrahydrofurfuryl and 2-(caprolactone)ethyl. Examples of fluoropolyether groups for R.sup.17 include, but are not limited to, --(CF.sub.2--CF.sub.2--O).sub.zH, --(CF(CF.sub.3)CF.sub.2O).sub.zH, --(CF.sub.2CF.sub.2O).sub.zCF.sub.3, --(CF(CF.sub.3)CF.sub.2O).sub.zCF.sub.3, where z is as defined above, --(CH.sub.2).sub.i(CF(CF.sub.3)).sub.j--(O--CF(CF.sub.3).sub.k--F where i has an average value of 0 to 10, j has an average value of 0 to 10 and k has an average value of 1 to 20. Examples of metal ions for R.sup.17 include, but are not limited to, positive ions such as Zn, Al, Ca, Na, Mg and K.

In formula ii), each R.sup.18 is independently a hydrogen atom, a monovalent hydrocarbon group of 1 to 4 carbon atoms, or CF.sub.3. Examples of monovalent hydrocarbon groups for R.sup.18 include alkyl such as methyl, ethyl, propyl, and butyl. Each R.sup.19 is independently a divalent organic group of 1 to 20 carbon atoms. Examples of divalent organic groups for R.sup.19 include, but are not limited to, alkylene such as methylene, ethylene, propylene, pentylene, neo-pentylene, octylene, undecylene, and octadecylene; cycloalkylene such as cylcohexylene; alkenylene such as vinylene, allylene, butenylene, and hexenylene; alkynylene such as ethynylene, propynylene, and butynylene; arylene such as phenylene, tolylene, xylylene, benzylene, and 2-phenylethylene; ether diol derivatives such as --(CH.sub.2CH.sub.2O).sub.z--CH.sub.2CH.sub.2-- and --CH(CH.sub.3)CH.sub.2O).sub.z--CH(CH.sub.3)CH.sub.2 where z is as defined above for R.sup.19; alkylene/arylene combinations such as 4,4'-isopropylidene diphenyl (also known as Bispheno