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US-12624256-B2 - Silicone pressure sensitive adhesive composition containing a cyanate-functional silane additive and methods for the preparation and use of said composition

US12624256B2US 12624256 B2US12624256 B2US 12624256B2US-12624256-B2

Abstract

A silicone pressure sensitive adhesive composition is curable to form a silicone pressure sensitive adhesive. The silicone pressure sensitive adhesive composition can be coated on a substrate and cured to form a topside protective film. The topside protective film can be used to protect an anti-fingerprint hard coating in a screen protective film on cover glass for a display device, such as a smartphone.

Inventors

  • Jingui Jiang
  • Zhihua Liu
  • Fuming Huang
  • Wenjie Chen
  • Chengrong Zhu
  • Jiayin Zhu

Assignees

  • DOW SILICONES CORPORATION

Dates

Publication Date
20260512
Application Date
20210708

Claims (17)

  1. 1 . A silicone pressure sensitive adhesive composition comprising: 30 weight % to <80 weight %, based on combined weights of starting materials (A) to (G), of (A) an alkenyl-functional polydiorganosiloxane comprising unit formula: (R M 2 R U SiO 1/2 ) a (R M 3 SiO 1/2 ) b (R M 2 SiO 2/2 ) c (R M R U SiO 2/2 ) d (R M SiO 3/2 ) e (R U SiO 3/2 ) f (SiO 4/2 ) g , where each R M is an independently selected alkyl group of 1 to 30 carbon atoms; each R U is an independently selected alkenyl group of 2 to 30 carbon atoms; and subscripts a, b, c, and d represent average numbers of each unit per molecule, subscript a≥0, subscript b≥0, subscript c≥0, subscript d≥0, subscript e≥0, subscript f≥0, a quantity (a+d+f)≥2, subscript g≥0, and a quantity (a+b+c+d+e+f+g) is 4 to 10,000; 0.5 weight % to 5 weight %, based on combined weights of starting materials (A) to (G), of (B) a polyorganohydrogensiloxane comprising unit formula (R M 3 SiO 1/2 ) dd (H cc R M (3-cc) SiO 1/2 ) h (SiO 4/2 ) i (ZO 1/2 ) ee , where R M is as described above, each Z is independently selected from the group consisting of hydrogen and R M , subscripts dd and h represent relative weights of monofunctional siloxane units in the formula, subscript i represents relative weight of tetrafunctional siloxane units in the formula, subscript dd≥0, subscript h>0, subscript i>0, subscripts dd, h, and i have values sufficient to provide the polyorganohydrogensiloxane with a weight ratio of monofunctional units: tetrafunctional units {(dd+h):i} of 0.4:1 to 2:1, subscript ee represents relative weight of hydrolyzable groups in the formula, subscript ee≥0, subscript ee has a value sufficient to provide 0 to 2 weight % of hydrolyzable groups based on weight of the polyorganohydrogensiloxane; subscript cc represents the number of silicon bonded hydrogen atoms in each monofunctional unit, 2≥cc≥1; and where starting material (B) is present in a sufficient amount to provide a molar ratio of silicon bonded hydrogen atoms to alkenyl groups in starting material (A) (SiH:Vi ratio) of 0.5 to 20; a sufficient amount of (C) a platinum group metal hydrosilylation reaction catalyst to provide 1 ppm to 5,200 ppm of the platinum group metal, based on combined weights of starting materials (A) to (G); 10 to 50 weight %, based on combined weights of starting materials (A) to (G), of (D) a polyorganosilicate resin; 8 weight % to 17 weight %, based on combined weights of starting materials (A) to (G), of (E) a cyanate-functional silane of formula R′R″ n Si(OR M ) 3−n , where R M is as described above, subscript n is 0 or 1, R′ is a cyano-substituted hydrocarbyl group, and R″ is selected from the group consisting of R′ and R M ; 0 to 5 weight %, based on combined weights of starting materials (A) to (G), of (F) an anchorage additive; 0.01 weight % to 5 weight %, based on combined weights of starting materials (A) to (G), of (G) a hydrosilylation reaction catalyst inhibitor; and 0 to 90 weight %, based on combined weights of all starting materials in the composition, of (H) a solvent.
  2. 2 . The composition of claim 1 , where (A) alkenyl-functional polydiorganosiloxane is selected from the group consisting of: (A1) an alkenyl-functional polydiorganosiloxane gum of unit formula (R M 2 R U SiO 1/2 ) j (R M 2 SiO 2/2 ) k (R M R U SiO 2/2 ) m (R M 3 SiO 1/2 ) n , where R M and R U are as described above; subscripts j, k, m, and n represent average numbers of each unit per molecule; subscript j is 0, 1, or 2; subscript n is 0, 1, or 2; a quantity (j+n)=2; subscript k≥0; subscript m≥0; a quantity (k+m) is 3,000 to 10,000; and a quantity (j+m)≥2; (A2) an alkenyl-functional polydiorganosiloxane polymer of unit formula (R M 2 R U SiO 1/2 ) o (R M 2 SiO 2/2 ) p (R M R U SiO 2/2 ) q (R M 3 SiO 1/2 ) r , where R M and R U are as described above; subscripts o, p, q and r, represent average numbers of each unit per molecule; subscript o is 0, 1, or 2; subscript r is 0, 1, or 2; a quantity (r+0)=2; subscript p≥0; subscript q≥0; a quantity (p+q) is 100 to 1,200; and a quantity (o+q)≥2; (A3) a branched alkenyl-functional polyorganosiloxane of unit formula (R M 3 SiO 1/2 ) u (R M 2 R U SiO 1/2 ) v (R M 2 SiO 2/2 ) s (SiO 4/2 ) t , where R M and R U are as described above; subscripts s, t, u, and v represent average numbers of each unit per molecule; 2≥u≥0; 4≥v≥0; 995≥s≥4; t=1; (u+v)=4; and (u+v+s+t) has a value sufficient to impart a viscosity>100 mPa·s measured at room temperature by rotational viscometry to the branched alkenyl-functional polyorganosiloxane; (A4) an alkenyl-functional silsesquioxane polymer of unit formula (R M 3 SiO 1/2 ) ii (R U R M 2 SiO 1/2 ) jj (R M 2 SiO 2/2 ) kk (R U R M SiO 2/2 ) mm (R M SiO 3/2 ) nn , where R M and R U are as described above; Subscripts ii, jj, kk, mm, and nn represent average numbers of each unit per molecule; subscript 12≥ii≥0, subscript 12≥jj>0, subscript 995≥kk≥15, subscript 10≥nn>0, and subscript 800≥mm≥0; and (A5) a combination of two or more of (A1), (A2), (A3), and (A4).
  3. 3 . The composition of claim 1 , where starting material (B), the polyorganohydrogensiloxane, comprises unit formula (HR M 2 SiO 1/2 ) h (SiO 4/2 ) i , where R M is as described above; and a weight ratio (h:i) is 1:1 to 2:1.
  4. 4 . The composition of claim 1 , where starting material (C), the hydrosilylation reaction catalyst, comprises a platinum-organosiloxane complex.
  5. 5 . The composition of claim 1 , where starting material (D) the polyorganosilicate resin, comprises unit formula: (R M 3 SiO 1/2 ) w (R M 2 R U SiO 1/2 ) x (SiO 4/2 ) y (ZO 1/2 ) z , where R M , R U , and Z are as described above; subscripts w, x, and y represent mole fractions of each unit in the formula, and have values such that w>0; x≥0; y>1; with the proviso that a quantity (w+x+y) has a value sufficient to provide the polyorganosilicate resin with a number average molecular weight of 1,000 g/mol to 10,000 g/mol; and subscript z is 0 to a value sufficient to give (D) the polyorganosilicate resin a hydrolyzable group content of up 4 weight % based on weight of the polyorganosilicate resin.
  6. 6 . The composition of claim 1 , where starting material (E), the cyanate-functional silane is selected from the group consisting of gamma-isocyanatopropyl trimethoxysilane; delta-isocyanatobutyl trimethoxysilane; 11-isocyanatoundecyl trimethoxysilane; gamma-isocyanatopropyl triethoxysilane; delta-isocyanatobutyl triethoxysilane; 11-isocyanatoundecyl triethoxysilane; and a combination thereof.
  7. 7 . The composition of claim 1 , where each R M is methyl and each R U is independently selected from the group consisting of vinyl, allyl, and hexenyl.
  8. 8 . The composition of claim 1 , where starting material (F), the anchorage additive, is present, and the anchorage additive is selected from the group consisting of (F-1) vinyltriacetoxysilane, (F-2) glycidoxypropyltrimethoxysilane, (F-3) a combination of (F-1) and (F-2), and (F-4) a combination of (F-3) and a polydimethylsiloxane terminated with hydroxyl groups, methoxy groups, or terminated with both a hydroxy group and a methoxy group.
  9. 9 . The composition of claim 1 , where starting material (G), the hydrosilylation reaction inhibitor, is selected from the group consisting of 1-ethynyl-1-cyclohexanol, methyl butynol, and diallyl maleate.
  10. 10 . The composition of claim 1 , where starting material (H), the solvent, is present and is selected from the group consisting of toluene, xylene, heptane, ethyl benzene, ethyl acetate, and a combination of two or more thereof.
  11. 11 . A silicone pressure sensitive adhesive prepared by curing a silicone pressure sensitive adhesive composition comprising: 30 weight % to <80 weight %, based on combined weights of starting materials (A) to (G), of (A) an alkenyl-functional polydiorganosiloxane comprising unit formula: (R M 2 R U SiO 1/2 ) a (R M 3 SiO 1/2 ) b (R M 2 SiO 2/2 ) c (R M R U SiO 2/2 ) d (R M SiO 3/2 ) e (R U SiO 3/2 ) f (SiO 4/2 ) g , where each R M is an independently selected alkyl group of 1 to 30 carbon atoms; each R U is an independently selected alkenyl group of 2 to 30 carbon atoms; and subscripts a, b, c, and d represent average numbers of each unit per molecule, subscript a≥0, subscript b≥0, subscript c≥0, subscript d≥0, subscript e≥0, subscript f≥0, a quantity (a+d+f)≥2, subscript g≥0, and a quantity (a+b+c+d+e+f+g) is 4 to 10,000; 0.5 weight % to 5 weight %, based on combined weights of starting materials (A) to (G), of (B) a polyorganohydrogensiloxane comprising unit formula (R M 3 SiO 1/2 ) dd (H cc R M (3−cc) SiO 1/2 ) h (SiO 4/2 ) i (ZO 1/2 ) ee , where R M is described above, each Z is independently selected from the group consisting of hydrogen and R M , subscripts dd and h represent relative weights of monofunctional siloxane units in the formula, subscript i represents relative weight of tetrafunctional siloxane units in the formula, subscript dd≥0, subscript h≥0, subscript i≥0, subscripts dd, h, and i have values sufficient to provide the polyorganohydrogensiloxane with a weight ratio of monofunctional units: tetrafunctional units {(dd+h):i} of 0.4:1 to 2:1, subscript ee represents relative weight of hydrolyzable groups in the formula, subscript ee≥0, subscript ee has a value sufficient to provide 0 to 2 weight % of hydrolyzable groups based on weight of the polyorganohydrogensiloxane: subscript cc represents the number of silicon bonded hydrogen atoms in each monofunctional unit, 2≥cc≥1; and where starting material (B) is present in a sufficient amount to provide a molar ratio of silicon bonded hydrogen atoms to alkenyl groups in starting material (A) (SiH:Vi ratio) of 0.5 to 20; a sufficient amount of (C) a platinum group metal hydrosilylation reaction catalyst to provide 1 ppm to 5,200 ppm of the platinum group metal, based on combined weights of starting materials (A) to (G); 10 to 50 weight %, based on combined weights of starting materials (A) to (G), of (D) a polyorganosilicate resin; 8 weight % to 17 weight %, based on combined weights of starting materials (A) to (G), of (E) a cyanate-functional silane of formula R′R″ n Si(OR M ) 3−n , where R M is as described above, subscript n is 0 or 1, R′ is a cyano-substituted hydrocarbyl group, and R″ is selected from the group consisting of R′ and R M ; 0 to 5 weight %, based on combined weights of starting materials (A) to (G), of (F) an anchorage additive; 0.01 weight % to 5 weight %, based on combined weights of starting materials (A) to (G), of (G) a hydrosilylation reaction catalyst inhibitor; and 0 to 90 weight %, based on combined weights of all starting materials in the composition, of (H) a solvent.
  12. 12 . The silicone pressure sensitive adhesive of claim 11 , where starting material (E), the cyanate-functional silane is selected from the group consisting of gamma-isocyanatopropyl trimethoxysilane; delta-isocyanatobutyl trimethoxysilane; 11-isocyanatoundecyl trimethoxysilane; gamma-isocyanatopropyl triethoxysilane; delta-isocyanatobutyl triethoxysilane; 11-isocyanatoundecyl triethoxysilane; and a combination thereof.
  13. 13 . A protective film comprising: 1) the silicone pressure sensitive adhesive of claim 11 , 2) a substrate having a surface, where the silicone pressure sensitive adhesive is coated on the surface of the substrate.
  14. 14 . A method comprising: optionally 1) treating a surface of a substrate, 2) coating a silicone pressure sensitive adhesive composition on the surface of the substrate, where the silicone pressure sensitive adhesive composition comprises: 30 weight % to <80 weight %, based on combined weights of starting materials (A) to (G), of (A) an alkenyl-functional polydiorganosiloxane comprising unit formula: (R M 2 R U SiO 1/2 ) a (R M 3 SiO 1/2 ) b (R M 2 SiO 2/2 ) c (R M R U SiO 2/2 ) d (R M SiO 3/2 ) e (R U SiO 3/2 ) f (SiO 4/2 ) g , where each R M is an independently selected alkyl group of 1 to 30 carbon atoms; each R U is an independently selected alkenyl group of 2 to 30 carbon atoms; and subscripts a, b, c, and d represent average numbers of each unit per molecule, subscript a≥0, subscript b≥0, subscript c≥0, subscript d≥0, subscript e≥0, subscript f≥0, a quantity (a+d+f)≥2, subscript g≥0, and a quantity (a+b+c+d+e+f+g) is 4 to 10,000; 0.5 weight % to 5 weight %, based on combined weights of starting materials (A) to (G), of (B) a polyorganohydrogensiloxane comprising unit formula (R M 3 SiO 1/2 ) dd (H cc R M (3−cc) SiO 1/2 ) h (SiO 4/2 ) i (ZO 1/2 ) ee , where R M is as described above, each Z is independently selected from the group consisting of hydrogen and R M, subscripts dd and h represent relative weights of monofunctional siloxane units in the formula, subscript i represents relative weight of tetrafunctional siloxane units in the formula, subscript dd≥0, subscript h≥0, subscript i≥0, subscripts dd, h, and i have values sufficient to provide the polyorganohydrogensiloxane with a weight ratio of monofunctional units: tetrafunctional units {(dd+h):i} of 0.4:1 to 2:1, subscript ee represents relative weight of hydrolyzable groups in the formula, subscript ee≥0, subscript ee has a value sufficient to provide 0 to 2 weight % of hydrolyzable groups based on weight of the polyorganohydrogensiloxane; subscript cc represents the number of silicon bonded hydrogen atoms in each monofunctional unit, 2≥cc≥1; and where starting material (B) is present in a sufficient amount to provide a molar ratio of silicon bonded hydrogen atoms to alkenyl groups in starting material (A) (SiH:Vi ratio) of 0.5 to 20; a sufficient amount of (C) a platinum group metal hydrosilylation reaction catalyst to provide 1 ppm to 5,200 ppm of the platinum group metal, based on combined weights of starting materials (A) to (G); 10 to 50 weight %, based on combined weights of starting materials (A) to (G), of (D) a polyorganosilicate resin; 8 weight % to 17 weight %, based on combined weights of starting materials (A) to (G), of (E) a cyanate-functional silane of formula R′R″ n Si(OR M ) 3−n , where R M is as described above, subscript n is 0 or 1, R′ is a cyano-substituted hydrocarbyl group, and R″ is selected from the group consisting of R′ and R M ; 0 to 5 weight %, based on combined weights of starting materials (A) to (G), of (F) an anchorage additive; 0.01 weight % to 5 weight %, based on combined weights of starting materials (A) to (G), of (G) a hydrosilylation reaction catalyst inhibitor; and 0 to 90 weight %, based on combined weights of all starting materials in the composition, of (H) a solvent, optionally 3) removing some or all of the solvent, when present, and 4) curing the pressure sensitive adhesive composition, thereby preparing a topside protective film comprising a silicone pressure sensitive adhesive having a first surface adhered to the surface of the substrate, the silicone pressure sensitive adhesive having a second surface opposite the first surface.
  15. 15 . The method of claim 14 , further comprising: 5) applying the second surface of the silicone pressure sensitive adhesive to an anti-fingerprint hard coating in a display device.
  16. 16 . The method of claim 15 , further comprising: 6). removing the silicone pressure sensitive adhesive from the anti-fingerprint hard coating in a display device with a dynamic coefficient of friction <0.5.
  17. 17 . The method of claim 14 , where starting material (E), the cyanate-functional silane is selected from the group consisting of gamma-isocyanatopropyl trimethoxysilane; delta-isocyanatobutyl trimethoxysilane; 11-isocyanatoundecyl trimethoxysilane; gamma-isocyanatopropyl triethoxysilane; delta-isocyanatobutyl triethoxysilane; 11-isocyanatoundecyl triethoxysilane; and a combination thereof.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a U.S. national stage filing under 35 U.S.C. § 371 of PCT Application No. PCT/CN2021/105220 filed on 8 Jul. 2021, currently pending. PCT Application No. PCT/CN2021/105220 is hereby incorporated by reference. TECHNICAL FIELD A silicone pressure sensitive adhesive composition can be cured on a substrate to form a topside protective film. The topside protective film is useful in electronics applications for protection of an anti-fingerprint hard coating layer in a screen protective film on a display glass. BACKGROUND Protective films can be used during fabrication and shipping of display devices, such as mobile phones and tablets. A topside protective film that adheres to an anti-fingerprint hard coating used in a display device, in order to protect cover glass from scratches and other damage during processing and/or shipping is desired. However, it is further desired that the topside protective cleanly release from the anti-fingerprint hard coating, e.g., without leaving residue discernable to an end user of the display device. SUMMARY A silicone pressure sensitive adhesive (Si-PSA) composition and method for its preparation are disclosed. The Si-PSA composition is curable to form a Si-PSA on various substrates. A topside protective film comprising the Si-PSA on a surface of a substrate may be used on an anti-fingerprint hard coating of a screen protective film on a cover glass useful in a display device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a partial cross section of a protective film used on an anti-fingerprint coating on a cover glass, which is suitable for use in a display device. REFERENCE NUMERALS 100 protective film100a screen protective film100b topside protective film101 polymeric substrate101b surface of polymeric substrate 101102 topside Si-PSA102a surface of topside Si-PSA 102102b opposing surface of topside Si-PSA 102103 anti-fingerprint hard coating103a surface of AF hard coating 103103b opposing surface of AF hard coating 103104 substrate104a surface of substrate 104104b opposing surface of substrate 104105 Si-PSA105a surface of Si-PSA 105105b opposing surface of Si-PSA 105106 anti-fingerprint coating106a surface of AF coating 106106b opposing surface of AF coating 106107 display cover glass107a surface of display cover glass 107 DETAILED DESCRIPTION The Si-PSA composition comprises: (A) an alkenyl-functional polyorganosiloxane; (B) a polyorganohydrogensiloxane: (C) a hydrosilylation reaction catalyst; (D) a polyorganosilicate resin; (E) an cyanate-functional silane; (F) an anchorage additive: (G) a hydrosilylation reaction inhibitor; and optionally (H) a solvent. Starting Material (A) Alkenyl-functional Polyorganosiloxane Starting material (A) in the Si-PSA composition is an alkenyl-functional polyorganosiloxane comprising unit formula (A-I): (RM2RUSiO1/2)a(RM3SiO1/2)b(RM2SiO2/2)c(RMRUSiO2/2)d(RMSiO3/2)e(RUSiO3/2)f(SiO4/2)g, where each RM is an independently selected alkyl group of 1 to 30 carbon atoms; each RU is an independently selected alkenyl group of 2 to 30 carbon atoms; and subscripts a, b, c, and d represent average numbers of each unit per molecule. In unit formula (A-I), subscript a≥0, subscript b≥0, subscript c≥0, subscript d≥0, subscript e≥0, subscript f≥0, a quantity (a+d+f)≥2, subscript g≥0, and a quantity (a+b+c+d+e+f+g) is 4 to 10,000. Each RM is an independently selected alkyl group of 1 to 30 carbon atoms. Alternatively, each RM may have 1 to 12 carbon atoms, alternatively 1 to 9 carbon atoms, alternatively 1 to 8 carbon atoms, and alternatively 1 to 6 carbon atoms. “Alkyl” means a cyclic, branched, or unbranched, saturated monovalent hydrocarbon group. Suitable alkyl groups for RM are exemplified by linear and branched alkyl groups such as methyl, ethyl, propyl (e.g., iso-propyl and/or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl, and/or sec-butyl), pentyl (e.g., isopentyl, neopentyl, and/or tert-pentyl), hexyl, heptyl, octyl, nonyl, and decyl, and branched alkyl groups of 6 to 30 carbon atoms; or cyclic alkyl groups such as cyclopentyl and cyclohexyl. Alternatively, each RM may be independently selected from the group consisting of linear alkyl and branched alkyl. Alternatively, each RM may be linear alkyl. Alternatively, each RM may be methyl. In unit formula (A-I), each RU is an independently selected monovalent alkenyl group of 2 to 30 carbon atoms. Alternatively, each RU may have 2 to 12 carbon atoms, alternatively 2 to 8 carbon atoms, and alternatively 2 to 6 carbon atoms. “Alkenyl” means a cyclic, branched or unbranched, monovalent hydrocarbon group having one or more carbon-carbon double bonds. Suitable alkenyl groups are exemplified by vinyl; allyl; isopropenyl; and butenyl, pentenyl, hexenyl, and heptenyl, (including branched and linear isomers of 4 to 7 carbon atoms); and cyclohexenyl. Alternatively, each RU may be linear alkenyl, such as vinyl, allyl, or hexenyl. Starting material (A)