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US-12624168-B2 - Methods for making polyfunctional organosiloxanes and compositions containing same

US12624168B2US 12624168 B2US12624168 B2US 12624168B2US-12624168-B2

Abstract

A polyfunctional organohydrogensiloxane is prepared using a boron containing Lewis acid as catalyst. The polyfunctional organohydrogensiloxane may be formulated into release coating compositions. Alternatively, the polyfunctional organohydrogensiloxane may be further functionalized with a curable group to form a clustered functional organosiloxane. The clustered functional organosiloxane may be formulated into thermal radical cure adhesive compositions.

Inventors

  • Eric JOFFRE
  • Nanguo Liu
  • Gang Lu
  • Zhenbin NIU
  • David Rich

Assignees

  • DOW SILICONES CORPORATION

Dates

Publication Date
20260512
Application Date
20230905

Claims (17)

  1. 1 . A method for preparing a product comprising: 1) reacting starting materials comprising B) a hydroxyl terminated polydiorganosiloxane of formula where subscript n is 2 to 2,000, and each R1 is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups; and C) a cyclic polyorganohydrogensiloxane of formula (RHSiO2/2) v, where subscript v is 3 to 12; and each R is an independently selected monovalent hydrocarbon group; thereby preparing the product comprising a polyfunctional organohydrogensiloxane and a by-product comprising H2 in the presence of A) a boron containing Lewis acid thereby preparing the product, which comprises a polyfunctional organohydrogensiloxane and a by-product comprising H2; where the polyfunctional organohydrogensiloxane has formula: where R, R1, subscript n and subscript v are as described above.
  2. 2 . The method claim 1 , where subscript n is 2 to 1,000, subscript v is 4 to 10, each R is an alkyl group of 1 to 6 carbon atoms, and each R 1 is selected from the group consisting of an alkyl group of 1 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, or a halogenated alkyl group of 1 to 20 carbon atoms.
  3. 3 . The method of claim 1 , further comprising: 2) during and/or after step 1), removing the H 2 generated during formation of the polyfunctional organohydrogensiloxane.
  4. 4 . The method of claim 1 , further comprising: 3) neutralizing residual boron containing Lewis acid in the polyfunctional organohydrogensiloxane.
  5. 5 . A method for preparing a product comprising: 1) reacting starting materials comprising B) a hydroxyl terminated polydiorganosiloxane of formula where subscript n is 2 to 2,000, and each R 1 is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups; and C) a cyclic polyorganohydrogensiloxane of formula (RHSiO 2/2 ) v , where subscript v is 3 to 12; and each R is an independently selected monovalent hydrocarbon group; thereby preparing the product comprising a polyfunctional organohydrogensiloxane and a by-product comprising H 2 in the presence of A) a boron containing Lewis acid, thereby preparing the product, which comprises a polyfunctional organohydrogensiloxane and a by-product comprising H 2 ; where the polyfunctional organohydrogensiloxane has unit formula: [(HRSiO 2/2 ) v-1 (—RSiO 2/2 )] 2 [O—(R 1 2 SiO 2/2 ) n ] n′ [(HRSiO 2/2 ) v-2 (—RSiO 2/2 ) 2 ] o′ , where subscripts n and v and R 1 and R are as described above, subscript o′ is 0 to 1, and subscript n′=(o′+1), 2) during and/or after step 1), removing the H 2 generated during formation of the polyfunctional organohydrogensiloxane, 3) neutralizing residual boron containing Lewis acid in the polyfunctional organohydrogensiloxane, and 4) removing a particulate derived from neutralizing the boron containing Lewis acid in step 3).
  6. 6 . The method of claim 1 , further comprising: recovering the polyfunctional organohydrogensiloxane.
  7. 7 . The method of claim 1 , where B) the hydroxyl terminated polydiorganosiloxane and C) the cyclic polyorganohydrogensiloxane are present in amounts sufficient to provide a molar ratio of silicon bonded hydrogen atoms to hydroxyl groups (SiH:OH ratio) of at least 1.8:1.
  8. 8 . The method of claim 2 , where each R is a methyl group, each R 1 is a methyl group, each subscript v is independently 1, 2, or 3, and subscript n is 5 to 15.
  9. 9 . A method for preparing a product comprising: 1) reacting starting materials comprising B) a hydroxyl terminated polydiorganosiloxane of formula where subscript n is 2 to 2,000, and each R 1 is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups; and C) a cyclic polyorganohydrogensiloxane of formula (RHSiO 2/2 ) v , where subscript v is 3 to 12; and each R is an independently selected monovalent hydrocarbon group; in the presence of A) a boron containing Lewis acid; thereby preparing a reaction product comprising a polyfunctional organohydrogensiloxane and a by-product comprising H 2 ; optionally 2) during and/or after step 1), removing the H 2 generated during formation of the polyfunctional organohydrogensiloxane; optionally 3) neutralizing residual boron containing Lewis acid in the polyfunctional organohydrogensiloxane; wherein steps 1), 2) and 3) are free of platinum group metal catalysts; optionally 4) removing a particulate derived from neutralizing the boron containing Lewis acid in step 3); optionally 5) recovering the polyfunctional organohydrogensiloxane; and 6) combining starting materials comprising a) the polyfunctional organohydrogensiloxane, b) a hydrosilylation reaction catalyst, and c) a reactive species having an average, per molecule at least one aliphatically unsaturated group capable of undergoing an addition reaction with a silicon bonded hydrogen atom of starting material a) and further comprising one or more curable groups per molecule; thereby preparing the product, which comprises a clustered functional organosiloxane of unit formula: [(R 8 RSiO 2/2 ) v-1 (—RSiO 2/2 )] 2 [O—(R 1 2 SiO 2/2 ) n ] n′ [(R 8 RSiO 2/2 ) v-2 (—RSiO 2/2 ) 2 ] o′ , where subscripts v and n and groups R and R 1 are as described above; subscript o′ is 0 to 100, subscript n′=(o′+1); and each R 8 is independently selected from the group consisting of H and a curable group, with the proviso that at least one R 8 per molecule is a curable group other than hydrogen.
  10. 10 . The method of claim 9 , where B) the hydroxyl terminated polydiorganosiloxane and C) the cyclic polyorganohydrogensiloxane are present in amounts sufficient to provide a molar ratio of silicon bonded hydrogen atoms to hydroxyl groups (SiH:OH ratio) of at least 4:1.
  11. 11 . The method of claim 9 , where o′ is 0 or 1.
  12. 12 . The method of claim 9 , where the reactive species comprises a silane of formula R 4 y SiR 5 (4-y) , where subscript y is 1 to 3, each R 4 is the aliphatically unsaturated group capable of undergoing an addition reaction, and each R 5 is the curable group; thereby preparing a product comprising a clustered functional organosiloxane.
  13. 13 . The method of claim 9 , where the reactive species has formula R 6 R 7 , where each R 6 is the aliphatically unsaturated group capable of undergoing an addition reaction, and each R 7 is the curable group.
  14. 14 . The method of claim 13 , where C) the reactive species is selected from the group consisting of allyl acrylate, allyl glycidyl ether, allyl methacrylate, and combinations thereof.
  15. 15 . The method of claim 14 , where C) the reactive species is allyl glycidyl ether.
  16. 16 . The method of claim 9 , where the clustered functional organosiloxane has SiH functionality in addition to the curable group introduced by starting material c).
  17. 17 . The method of claim 9 , where the product comprises a clustered functional polyorganosiloxane of formula: where each subscript p is 1, 2, or 3, 2≤n≤10, each R is methyl, phenyl, or trifluoropropyl; and each R8 is H or glycidyloxypropyl, with the proviso that said clustered functional polyorganosiloxane has an average of two glycidyloxypropyl groups per molecule.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation in part of U.S. patent application Ser. No. 17/277,644, filed on 4 Dec. 2019, and claims priority thereto under 35 U.S.C. § 120 and 35 U.S.C. § 365, and U.S. patent application Ser. No. 17/277,644 is a U.S. national stage filing under 35 U.S.C. § 371 of PCT Application Serial No. PCT/US19/064350, which claims the benefit of U.S. Provisional Patent Application No. 62/783,229 filed 21 Dec. 2018 under 35 U.S.C. § 119 (e). U.S. patent application Ser. No. 17/277,644, PCT Application Serial No. PCT/US19/064350, and U.S. Provisional Patent Application No. 62/783,229 are hereby incorporated by reference. TECHNICAL FIELD A method for making a polyfunctional organosiloxane is disclosed. The polyfunctional organosiloxane comprises a linear polydiorganosiloxane backbone with cyclic siloxane endblockers. The polyfunctional organosiloxane is useful in curable compositions, e.g., as a crosslinker. BACKGROUND Methods for making polyfunctional organosiloxane crosslinkers having linear polydiorganosiloxane backbones with cyclic siloxane endblockers have been proposed using platinum catalyzed reaction of cyclic polyorganohydrogensiloxanes with either vinyl terminated polydiorganosiloxanes or hydroxyl terminated polydiorganosiloxanes. These methods suffer from the drawbacks of requiring purification of the cyclic polyorganohydrogensiloxanes, which is costly. These methods further suffer from the drawback of poor ability to control structure and molecular weight of the products. SUMMARY A method for preparing a polyfunctional organohydrogensiloxane using a boron containing Lewis acid as catalyst is disclosed. The method may further comprise functionalizing the polyfunctional organohydrogensiloxane to form a clustered functional organosiloxane. The polyfunctional organohydrogensiloxane and the clustered functional organosiloxane are useful in curable compositions. DETAILED DESCRIPTION OF THE INVENTION The polyfunctional organohydrogensiloxane prepared by the method described herein comprises a linear polydiorganosiloxane backbone with cyclic SiH functional endblockers. The polyfunctional organohydrogensiloxane may be used as a crosslinker. The polyfunctional organohydrogensiloxane is useful in curable compositions, such as release coating compositions. A method for preparing a product comprising the polyfunctional organohydrogensiloxane comprises the steps of: 1) combining starting materials comprisingA) a boron containing Lewis acid;B) a hydroxyl terminated polydiorganosiloxane of formula where each subscript n is 2 to 2,000, and each R1 is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups; and C) a cyclic polyorganohydrogensiloxane of formula (RHSiO2/2)v, where subscript v is 3 to 12; and each R is an independently selected monovalent hydrocarbon group; thereby preparing the product comprising the polyfunctional organohydrogensiloxane and a by-product comprising H2. The starting materials in step 1) may optionally further comprise D) a solvent. The method may optionally further comprise one or more additional steps. The method may further comprise recovering the polyfunctional organohydrogensiloxane. The method may further comprise: 2) during and/or after step 1), removing the H2 generated during formation of the polyfunctional organohydrogensiloxane and/or 3) neutralizing residual boron containing Lewis acid in the product. By-product H2 may be removed by any convenient means, such as stripping and/or burning. Neutralizing may be performed by adding E) a neutralizing agent to the product and thereafter filtering the product. Steps 2) and 3) may be performed in any order. If a particulate by-product is present, e.g., as a result of neutralization, the method may further comprise 4) removing a particulate such as alumina after neutralization by any convenient means, such as filtration. One or more of the method steps may be performed at a temperature of 5° C. to 70° C., alternatively 5° C. to 65° C., alternatively 10° C. to 60° C., alternatively 15° C. to 50° C., alternatively 20° C. to 35° C., alternatively 5° C. to 30° C., and alternatively 30° C. Alternatively, step 1) may be performed at the temperature of 5° C. to 70° C., alternatively 5° C. to 65° C., alternatively 10° C. to 60° C., alternatively 15° C. to 50° C., alternatively 20° C. to 35° C., alternatively 5° C. to 30° C., and alternatively 30° C. Without wishing to be bound by theory, it is thought that performing the method, particularly step 1) at relatively low temperatures (e.g., 90° C. or less, alternatively 80° C. or less, alternatively 70° C. or less, and alternatively 50° C. or less) may provide improved reaction rate, yield, or both. The starting materials used in step 1) of the method, alternatively steps 1), 2), and 3) of the method, may be free of platinum group metal catalysts. The resulting product and