Hydrosilylation-reaction curable composition for forming a silicone pressure-sensitive adhesive that adheres to an optical silicone elastomer, and its preparation and method of use in a flexible display device

Abstract

The present invention provides a silicone pressure-sensitive adhesive, which is prepared by curing a hydrosilylation reaction-curable composition. The composition comprises: (A) a polydiorganosiloxane gum component, (B) a polyorganosilicate resin component, (C) a hydrosilylation reaction catalyst, (D) a polyorganohydrogensiloxane, (E) an alkyl borate, (F) a hydrosilylation reaction inhibitor, (G) a solvent, and (H) an anchoring additive. The silicone pressure-sensitive adhesive adheres to an optical silicone elastomer and can be used to prepare components of a flexible display device.

Description

[0001] Cross - reference to related applications

[0002] None Technical field

[0003] The present invention relates to a silicone pressure - sensitive adhesive and methods for its preparation and use. More specifically, the present invention relates to a hydrosilylation - curable composition that cures to form a silicone pressure - sensitive adhesive suitable for flexible display devices. Background art

[0004] Flexible display devices that can be deformed, for example, by bending, folding, winding, rolling up, or stretching are being developed. Flexible display devices can be deformed according to the needs of consumers or the circumstances in which the flexible display device is used. Generally, the various components of a display device are made of multiple layers, and it is important that these layers adhere to each other and do not suffer damage that causes component failure when the flexible display device is deformed.

[0005] Optical silicone elastomers can be used to form light - transmissive (e.g., transparent or translucent) layers in flexible display devices. Optical silicone elastomers are known in the art and are commercially available. For example, SILASTIC TM MS - 1001, MS - 1002, MS - 1003, MS - 4001, MS - 4002, and MS - 4007 are moldable optical silicone elastomers, and SYLGARD TM 182, 184, and 186 are also optical silicone elastomers, all of which are commercially available from Dow Silicones Corporation, Midland, Michigan, USA.

[0006] However, optical silicone elastomers (such as those described above) may have the disadvantage of being difficult to adhere to other layers in flexible display devices. Therefore, there is a need in the industry for a silicone pressure - sensitive adhesive that can adhere to optical silicone elastomers and does not cause failure of flexible display devices. Summary of the invention

[0007] A hydrosilylation - curable composition capable of forming a silicone pressure - sensitive adhesive is provided. A method for preparing the composition and a method for using the composition to manufacture an article are provided. The article can form a component of a flexible display device. Brief description of the drawings

[0008] Figure 1 A partial cross - section of the components of a flexible display device 100 is shown.

[0009] Reference numeral

[0010] 100 Part of a flexible display device component

[0011] 101 Substrate

[0012] 101b Surface of substrate 101

[0013] 102 Silicone pressure - sensitive adhesive

[0014] 102a Surface of silicone pressure - sensitive adhesive 102

[0015] 102b Opposite surface of silicone pressure - sensitive adhesive 102

[0016] 103 Optical silicone elastomer

[0017] 103a Surface of optical silicone elastomer 103 Detailed implementation mode

[0018] The hydrosilylation - curable composition for forming a silicone pressure - sensitive adhesive contains:

[0019] (A) Polydiorganosiloxane gum component, which contains

[0020] Based on the combined weight of starting materials (A) to (F), 32.2 wt% to 44.6 wt% of the unit formula (R M 2 R U SiO 1 / 2 ) 2 (R M 2 SiO 2 / 2 ) a of (A - 1) aliphatically unsaturated polydiorganosiloxane gum, where each R M is a monovalent hydrocarbon group having 1 to 30 carbon atoms independently selected and free of aliphatic unsaturated groups; each R U is a monovalent aliphatically unsaturated hydrocarbon group having 2 to 30 carbon atoms independently selected; and the subscript a has a value sufficient to give the polydiorganosiloxane gum a plasticity of 50 to 200; and

[0021] 0 wt% to <1.2 wt% of the unit formula ((HO)R M 2 SiO 1 / 2 ) 2 (R M 2 SiO 2 / 2 ) a’ of (A - 2) hydroxyl - terminated polydiorganosiloxane gum, where each R Mis a monovalent hydrocarbon group having from 1 to 30 carbon atoms, independently selected and free of aliphatic unsaturated groups; each subscript a' has a value sufficient to impart a plasticity to the polydiorganosiloxane gum of from 20 mils (0.51 mm) to 80 mils (2.03 mm);

[0022] provided that the weight ratio of (A-1) the aliphatic unsaturated polydiorganosiloxane gum : (A-2) the hydroxyl-terminated polydiorganosiloxane gum {(A-1):(A-2) ratio} ≥ 37.4:1;

[0023] (B) a polyorganosilicate resin component, which comprises

[0024] 44.8% to 58.9% by weight, based on the combined weight of starting materials (A) to (F), of the unitary (R M 3 SiO 1 / 2 ) z (SiO 4 / 2 ) o Z p capped resin of (B-1), where Z is a hydrolysable group, the subscript p is from 0 to a value sufficient to impart a hydrolysable group content of at most 2% to the capped resin, and the values of the subscripts z and o are such that z > 4, o > 1, and the quantity (z + o) has a value sufficient to provide the capped resin with a number-average molecular weight of from 500 g / mol to 2,700 g / mol; and

[0025] 0% to 7% by weight, based on the combined weight of starting materials (A) to (F), of the unitary (R M 3 SiO 1 / 2 ) z’ (SiO 4 / 2 ) o’ Z p’ uncapped resin of (B-2), where the subscript p' has a value sufficient to impart a hydrolysable group content of > 3% to 10% to the uncapped resin, and the values of the subscripts z' and o' are such that z' > 4, o' > 1, and the quantity (z' + o') has a value sufficient to provide the uncapped resin with a number-average molecular weight of from 500 g / mol to 5,000 g / mol, where, based on the combined weight of starting materials (A) to (F), (B-1) the capped resin and (B-2) the uncapped resin are present in a combined amount of 44.8% to 65.8% by weight, provided that the weight ratio of (B-2) the uncapped resin : (B-1) the capped resin {(B-2):(B-1) ratio} is from 0.032:1 to 0.125:1;

[0026] wherein component (A) the polydiorganosiloxane gum and component (B) the polyorganosilicate resin are present in a weight ratio of (B):(A) of ≤2.0:1 (resin:gum ratio);

[0027] 0.01 wt% to 5 wt% of (C) a hydrosilylation catalyst, based on the combined weight of starting materials (A) to (F);

[0028] (D) a polyorganohydrogensiloxane of the unit formula (R M 2 SiO 2 / 2 ) e (HR M SiO 2 / 2 ) f (R M 2 HSiO 1 / 2 ) g (R M 3 SiO 1 / 2 ) h wherein subscript e≥0, subscript f≥0, the amount (e + f) is from 4 to 500, subscript g is 0, 1 or 2, subscript h is 0, 1 or 2, the amount (g + h) = 2, and the amount (f + g) ≥ 3; wherein component (D) the polyorganohydrogensiloxane is present in an amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms to aliphatic unsaturated hydrocarbon groups of component (A) the polydiorganosiloxane gum of 20.8:1 to 57.7:1 {(D):(A) ratio};

[0029] 0.05 wt% to 4.64 wt% of (E) a trialkyl borate, based on the combined weight of starting materials (A) to (F);

[0030] 0 wt% to 5 wt% of (F) a hydrosilylation inhibitor, based on the combined weight of starting materials (A) to (F); and

[0031] >0 wt% to 90 wt% of (G) a solvent, based on the combined weight of all starting materials in the composition; and

[0032] 0 wt% to 5 wt% of (H) an anchoring additive, based on the combined weight of starting materials (A) to (F).

[0033] (A) Polydiorganosiloxane gum component

[0034] The hydrosilylation-curable composition comprises (A) a polydiorganosiloxane gum component. The polydiorganosiloxane gum component comprises: (A-1) an aliphatic unsaturated polydiorganosiloxane gum and (A-2) a hydroxyl-terminated polydiorganosiloxane gum.

[0035] The starting material (A-1), an aliphatic unsaturated polydiorganosiloxane gum, has the unit formula (R M 2 R U SiO 1 / 2 ) 2 (R M 2 SiO 2 / 2 ) a , where each R M is a monovalent hydrocarbon group having 1 to 30 carbon atoms, independently selected and free of aliphatic unsaturated groups; each R U is a monovalent aliphatic unsaturated hydrocarbon group having 2 to 30 carbon atoms, independently selected; and the subscript a has a value sufficient to impart to the (A-1) aliphatic unsaturated polydiorganosiloxane gum a plasticity of from 20 mils (0.51 mm) to 80 mils (2.03 mm), alternatively from 30 mils (0.76 mm) to 70 mils (1.78 mm), and alternatively from 55 mils (1.40 mm) to 65 mils (1.65 mm), where the plasticity is measured based on ASTM D926 by applying a 1 kg load to a spherical sample weighing 4.2 g at 25 °C for 3 minutes, and the result is measured in thousandths of an inch (mils), and the procedure is carried out in accordance with ASTM D926.

[0036] In the unit formula (A-1), each R M is a monovalent hydrocarbon group having 1 to 30 carbon atoms, independently selected and free of aliphatic unsaturated groups. Alternatively, each R M can have 1 to 12 carbon atoms, alternatively 1 to 6 carbon atoms. R MExamples of suitable monovalent hydrocarbon groups include alkyl groups and aromatic groups, such as aryl groups and aralkyl groups. "Alkyl" means a cyclic, branched or unbranched saturated monovalent hydrocarbon group. Examples of alkyl include, but are not limited to, methyl, ethyl, propyl (e.g., isopropyl 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 having 6 or more carbon atoms; and cycloalkyl groups, such as cyclopentyl and cyclohexyl. "Aryl" means a cyclic, completely unsaturated hydrocarbon group. Examples of aryl include, but are not limited to, cyclopentadienyl, phenyl, anthracenyl and naphthyl. Monocyclic aryl groups can have 5 to 9 carbon atoms, alternatively 6 to 7 carbon atoms and alternatively 5 to 6 carbon atoms. Polycyclic aryl groups can have 10 to 17 carbon atoms, alternatively 10 to 14 carbon atoms and alternatively 12 to 14 carbon atoms. "Aralkyl" means an alkyl group having a side chain aryl group and / or a terminal aryl group or an aryl group having a side chain alkyl group. Exemplary aralkyl groups include tolyl, xylyl, benzyl, phenethyl, phenylpropyl and phenylbutyl. Alternatively, each R M can be independently selected from the group consisting of alkyl and aryl. Alternatively, each R M can be independently selected from methyl and phenyl. Alternatively, each R M can be alkyl. Alternatively, each R M can be methyl.

[0037] In unit (A-1), each R U is an independently selected monovalent aliphatic unsaturated hydrocarbon group having 2 to 30 carbon atoms. Alternatively, each R U can have 2 to 12 carbon atoms, alternatively 2 to 6 carbon atoms. Suitable monovalent aliphatic unsaturated hydrocarbon groups include alkenyl groups and alkynyl groups. "Alkenyl" means a branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. Examples of suitable alkenyl groups include vinyl, allyl, butenyl, pentenyl, hexenyl and heptenyl (including branched and straight-chain isomers having 3 to 7 carbon atoms); and cyclohexenyl. "Alkynyl" means a branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon triple bonds. Examples of suitable alkynyl groups include ethynyl, propynyl and butynyl (including branched and straight-chain isomers having 2 to 4 carbon atoms). Alternatively, each R U can be alkenyl, such as vinyl, allyl or hexenyl.

[0038] Polydiorganosiloxane gums are known in the art and can be prepared by methods such as hydrolysis and condensation of corresponding organohalosilanes or equilibration of cyclic polydiorganosiloxanes. Examples of suitable polydiorganosiloxane gums for hydrosilylation-curable compositions are:

[0039] i) Polydimethylsiloxane endblocked with dimethylvinylsilyloxy,

[0040] ii) Poly(dimethylsiloxane / methylphenyl)siloxane endblocked with dimethylvinylsilyloxy,

[0041] iii) Poly(dimethylsiloxane / diphenyl)siloxane endblocked with dimethylvinylsilyloxy,

[0042] iv) Polydimethylsiloxane endblocked with phenyl, methyl, vinyl - silyloxy,

[0043] v) Polydimethylsiloxane endblocked with dimethylhexenylsilyloxy,

[0044] vi) Poly(dimethylsiloxane / methylphenyl)siloxane endblocked with dimethylhexenyl - silyloxy,

[0045] vii) Poly(dimethylsiloxane / diphenyl)siloxane endblocked with dimethylvinylsilyloxy,

[0046] viii) A combination of two or more of i) to vii). Alternatively, the polydiorganosiloxane gum may be selected from the group consisting of: i) Polydimethylsiloxane endblocked with dimethylvinylsilyloxy,

[0047] v) Polydimethylsiloxane endblocked with dimethylhexenylsilyloxy, and a combination of i) and v).

[0048] Based on the combined weight of starting materials (A) to (F), the starting material (A - 1) aliphatic unsaturated polydiorganosiloxane gum is present in the hydrosilylation - curable composition in an amount of at least 32.2% by weight, alternatively at least 34% by weight, and alternatively at least 34.2% by weight, while this amount may be at most 44.62% by weight, alternatively at most 35% by weight, and alternatively at most 34.4% by weight. Alternatively, based on the combined weight of starting materials (A) to (F), the amount of (A - 1) aliphatic unsaturated polydiorganosiloxane gum may be from 32.2% by weight to 44.6% by weight, alternatively from 34% by weight to 35% by weight.

[0049] In addition to the (A - 1) aliphatic unsaturated polydiorganosiloxane gum, the starting material (A) polydiorganosiloxane component may optionally further comprise units of the formula (R M 2 R U SiO 1 / 2 ) 2 (R M 2 SiO 2 / 2 )a’ (A-2) hydroxy-terminated polydiorganosiloxane gum, wherein R M and R U are as described above; and the subscript a' has a value sufficient to impart a plasticity to the (A-2) hydroxy-terminated polydiorganosiloxane gum of from 20 mils (0.51 mm) to 80 mils (2.03 mm), alternatively from 30 mils (0.76 mm) to 70 mils (1.78 mm), and alternatively from 45 mils (1.14 mm) to 65 mils (1.65 mm), where the plasticity is measured based on ASTM D926 by applying a 1 kg load to a spherical sample weighing 4.2 g at 25 °C for 3 minutes, and the result is measured in thousandths of an inch (mils), and the procedure is based on ASTM D926.

[0050] Hydroxy-terminated polydiorganosiloxane gums suitable as starting material (A-2) are known in the art and can be prepared by methods such as hydrolysis and condensation of corresponding organohalosilanes or equilibration of cyclic polydiorganosiloxanes. Examples of suitable hydroxy-terminated polydiorganosiloxane gums for use as starting material (A-2) in hydrosilylation reaction curable compositions are:

[0051] i) Dihydroxy-terminated polydimethylsiloxane,

[0052] ii) Dihydroxy-terminated poly(dimethylsiloxane / methylphenylsiloxane),

[0053] iii) Dihydroxy-terminated poly(dimethylsiloxane / diphenylsiloxane),

[0054] iv) Phenyl, methyl, hydroxy-methylsiloxy-terminated polydimethylsiloxane,

[0055] v) A combination of two or more of i) to iv). Alternatively, the starting material (A-2) comprises dihydroxy-terminated polydimethylsiloxane.

[0056] Based on the combined weight of starting materials (A) to (F), the (A-2) hydroxy-terminated polydiorganosiloxane gum is present in the hydrosilylation reaction curable composition in an amount of from 0 wt% to <1.2 wt%. Alternatively, the (A-2) hydroxy-terminated polydiorganosiloxane gum can be present in an amount of at least 0.1 wt%, alternatively at least 0.13 wt%, while on the same basis, the amount can be at most 1.19%, alternatively at most 0.5%.

[0057] The starting materials (A-1) an aliphatically unsaturated polydiorganosiloxane gum and (A-2) a dihydroxy-terminated polydiorganosiloxane can be present in an amount such that the weight ratio (A-1):(A-2) can be ≥ 37.4:1. Alternatively, the weight ratio (A-1):(A-2) can be at least 37.4:1, alternatively at least 50:1, alternatively at least 100:1, alternatively at least 150:1, alternatively at least 200:1, alternatively at least 250:1 and alternatively at least 270:1; simultaneously, when there is present (A-2) a hydroxy-terminated polydiorganosiloxane gum, the weight ratio (A-1):(A-2) can be at most 350:1, alternatively at most 340:1, alternatively at most 325:1, alternatively at most 300:1, alternatively at most 275:1.

[0058] (B) Polysilicate resin component

[0059] The hydrosilylation-curable composition further comprises a starting material (B) a polyorganosilicate resin component, which component comprises (B-1) a capped resin and (B-2) an uncapped resin. The polyorganosilicate resin comprises monofunctional units (“M” units) of the formula R M 3 SiO 1 / 2 and tetrafunctional silicate units (“Q” units) of the formula SiO 4 / 2 wherein R M is as described above. Alternatively, at least one third, or at least two thirds, of the R M groups are alkyl groups (e.g., methyl groups). Alternatively, examples of M units can be (Me 3 SiO 1 / 2 ) and (Me 2 PhSiO 1 / 2 ). The polyorganosilicate resin is soluble in solvents such as those described below, examples being liquid hydrocarbons such as benzene, toluene, xylene and heptane; or liquid organosilicon compounds such as low-viscosity linear and cyclic polydiorganosiloxanes.

[0060] When prepared, the polyorganosilicate resin comprises the above M and Q units, and the polyorganosiloxane further comprises units having silicon-bonded hydroxy groups and can comprise neopentyloligomers of the formula Si(OsiR M 3 ) 4 wherein R M is as described above, for example, the neopentyloligomer can be tetrakis(trimethylsilyloxy)silane. 29Si NMR spectroscopy can be used to measure the hydroxyl content and molar ratio of M and Q units, where the ratio is expressed as {M(resin)} / {Q(resin)}, excluding M and Q units from neopentamers. The M:Q ratio represents the molar ratio of the total number of triorganosiloxy groups (M units) in the resin portion of the polyorganosilicate resin to the total number of silicate groups (Q units) in the resin portion. The M:Q ratio can be from 0.5:1 to 1.5:1.

[0061] The Mn of the polyorganosilicate resin depends on various factors, including the type of hydrocarbon group represented by R M When the peak representing the neopentamer is excluded from the measurement results, the Mn of the polyorganosilicate resin refers to the number average molecular weight measured using GPC. The Mn of the polyorganosilicate resin is 500 g / mol to 5,000 g / mol, or 2,500 g / mol to 5,000 g / mol, or 2,700 g / mol to 4,900 g / mol, or 2,700 g / mol to 4,700 g / mol. The GPC test method applicable to measuring Mn is disclosed in Referential Example 1 in Column 31 of U.S. Patent 9,593,209.

[0062] U.S. Patent 8,580,073, lines 5 of column 3 to line 31 of column 4 and U.S. Patent Publication 2016 / 0376482, paragraphs

[0023] to

[0026] are hereby incorporated by reference to disclose MQ resins, which are suitable polyorganosilicate resins for the hydrosilylation reaction curable compositions described herein. The polyorganosilicate resin can be prepared by any suitable method such as co-hydrolysis of corresponding silanes or by a silica sol capping method. The polyorganosilicate resin can be prepared by a silica sol capping method such as those disclosed in U.S. Patent 2,676,182 to Daudt et al.; U.S. Patent 4,611,042 to Rivers-Farrell et al.; and U.S. Patent 4,774,310 to Butler et al. The method of Daudt et al. mentioned above involves reacting a silica sol with a hydrolyzable triorganosilane (such as trimethylchlorosilane), a siloxane (such as hexamethyldisiloxane) or a mixture thereof under acidic conditions, and recovering a copolymer having M and Q units. The resulting copolymer typically contains 2 wt% to 5 wt% of hydroxyl groups.

[0063] Intermediates for preparing the polyorganosilicate resin can be triorganosilanes and silanes having four hydrolyzable substituents or alkali metal silicates. The triorganosilane can have the formula R M 3 SiX 1 where R M is as described above and X1 represents a hydrolysable substituent such as halogen, alkoxy, acyloxy, hydroxy, oxime or ketoxime group; alternatively, halogen, alkoxy or hydroxy. A silane having four hydrolysable substituents may have the formula SiX 2 4 , where each X 2 is halogen, alkoxy or hydroxy. Suitable alkali metal silicates include sodium silicate.

[0064] The polyorganosilicate resin prepared as described above is an uncapped resin that typically contains silicon-bonded hydroxy groups, for example, of the formula HOSi 3 / 2 and / or HOR M 2 SiO 1 / 2 . As measured by NMR spectroscopy, the polyorganosilicate resin may contain >3% to 10% of silicon-bonded hydroxy groups. For certain applications, it may be desirable for the amount of silicon-bonded hydroxy groups to be ≤2%, alternatively ≤0.89%, alternatively <0.7%, alternatively below 0.3%, alternatively less than 1% and alternatively 0.3% to 2%. The silicon-bonded hydroxy groups formed during the preparation of the polyorganosilicate resin can be converted to trihydrocarbyloxysilyl groups or to different hydrolysable groups by reacting the organosilicon resin with a silane, disiloxane or disilazane containing appropriate end groups in a process called capping. The silane containing a hydrolysable group can be added in an amount in excess of the amount required to react with the silicon-bonded hydroxy groups on the polyorganosilicate resin.

[0065] When the polyorganosilicate resin is a capped resin, the capped resin may contain 2% or less, or 0.7% or less, or 0.3% or less, or 0.3% to 0.8% of units represented by the formula HOSiO 3 / 2 and / or HOR M 2 SiO 1 / 2 , where R M is as described above. The concentration of silanol groups present in the polyorganosiloxane can be determined using NMR spectroscopy as described above.

[0066] Thus, the polyorganosilicate resin component comprises (B-1) a capped resin as described above and (B-2) an uncapped resin as described above. The capped resin may have the unit formula (R M 3 SiO 1 / 2 ) z (SiO 4 / 2 ) o Z p , where R MAs described above, and the values of the subscripts z and o are such that o > 1 and the subscript z > 4, the quantity (o + z) has a value sufficient to impart the above Mn to the end-capped resin (e.g., 500 g / mol to 5,000 g / mol, or 1,000 g / mol to 4,700 g / mol, or 2,900 g / mol to 4,700 g / mol, or 2,900 g / mol to 4,100 g / mol), and the subscript p has a value sufficient to impart the hydrolyzable group content as described above (e.g., 0% to 2%, or 0% to 0.7%, or 0% to 0.3%) to the end-capped resin. The starting material (B-2) uncapped resin may have the unit formula (R M 3 SiO 1 / 2 ) z’ (SiO 4 / 2 ) o’ Z p’ , where R M As described above, and the values of the subscripts z' and o' are such that o' > 1 and the subscript z' > 4, the quantity (o' + z') has a value sufficient to impart the above Mn to the uncapped resin (e.g., 500 g / mol to 5,000 g / mol, or 1,000 g / mol to 4,700 g / mol, or 2,700 g / mol to 4,700 g / mol, or 2,700 g / mol to 4,300 g / mol), and the subscript p' has a value sufficient to impart the hydrolyzable group content as described above (e.g., > 3% to 10%) to the uncapped resin.

[0067] Based on the combined weight of starting materials (A) to (F) (e.g., based on the combined weight of all starting materials in the hydrosilylation reaction curable composition, excluding solvents), the hydrosilylation reaction curable composition contains (B) a polyorganosilicate resin in an amount of 44.8 wt% to 65.8 wt%, alternatively 46.2 wt% to 65.8 wt%, and alternatively 61.5 wt% to 62.6 wt%. The amounts of the end-capped resin and the uncapped resin in starting material (B) may be sufficient to provide an uncapped resin:end-capped resin weight ratio of 0.032:1 to 0.125:1, alternatively 0.118:1 to 0.124:1, and alternatively 0.123:1 to 0.124:1 (i.e., the (B-2):(B-1) ratio). Alternatively, the (B-2):(B-1) ratio can be at least 0.032, alternatively at least 0.11, and alternatively at least 0.118, while the (B-2):(B-1) ratio can be at most 0.125, alternatively at most 0.124, and alternatively at most 0.12.

[0068] The starting material (A), a polydiorganosiloxane gum component, and the starting material (B), a polyorganosilicate resin component, may be present in the hydrosilylation reaction curable composition in amounts sufficient to provide a weight ratio of (B) polyorganosilicate resin component : (A) polydiorganosiloxane gum component of ≤ 2.0:1 {i.e., (B):(A) ratio}. Alternatively, the (B):(A) ratio may be at least 1.5:1, alternatively < 1.8:1, while the (B):(A) ratio may be at most 2.0:1, alternatively at most 1.8:1. Alternatively, the (B):(A) ratio may be from 1.0:1 to 2.0:1, alternatively from 1.8:1 to 1.9:1.

[0069] (C) Hydrosilylation catalyst

[0070] The starting material (C) in the hydrosilylation-curable composition is a hydrosilylation catalyst. Hydrosilylation catalysts are known in the art and are commercially available. Hydrosilylation catalysts include platinum group metal catalysts. Such hydrosilylation catalysts can be (C-1) metals selected from the following: platinum, rhodium, ruthenium, palladium, osmium, and iridium; alternatively platinum, ruthenium, and iridium; and alternatively the metal can be platinum. Alternatively, the hydrosilylation catalyst can be (C-2) a compound of such a metal, such as tris(triphenylphosphine)rhodium(I) chloride (Wilkinson's Catalyst), rhodium diphosphine chelates such as [1,2-bis(diphenylphosphino)ethane]dichlorodirhodium or [1,2-bis(diethylphosphino)ethane]dichlorodirhodium, chloroplatinic acid (Speier's Catalyst), chloroplatinic acid hexahydrate, or platinum dichloride. Alternatively, the hydrosilylation catalyst can be (C-3) a complex of a platinum group metal compound and an alkenyl-functionalized organopolysiloxane oligomer, or (C-4) a platinum group metal compound microencapsulated in a matrix or core-shell type structure. The complex of platinum and an alkenyl-functionalized organopolysiloxane oligomer includes the complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and platinum (Karstedt's Catalyst). Alternatively, the hydrosilylation catalyst can comprise (C-5) a complex microencapsulated in a resin matrix. Exemplary hydrosilylation catalysts are those described in U.S. Patent 2,823,218 to Speier, U.S. Patent 3,159,601 to Ashby, U.S. Patent 3,220,972 to Lamoreaux, U.S. Patent 3,296,291 to Chalk et al., U.S. Patent 3,419,593 to Willing, U.S. Patent 3,516,946 to Modic, U.S. Patent 3,715,334 to Karstedt, U.S. Patent 3,814,730 to Karstedt, U.S. Patent 3,928,629 to Chandra, U.S. Patent 3,989,668 to Lee et al., U.S. Patent 4,766,176 to Lee et al., U.S. Patent 4,784,879 to Lee et al., U.S. Patent 5,017,654 to Togashi, U.S. Patent 5,036,117 to Chung et al., U.S. Patent 5,175,325 to Brow, and EP 0 347 895 A to Togashi et al. Hydrosilylation catalysts are commercially available, such as SYL-OFF TM 4000 catalyst and SYL-OFF TM 2700 are available from Dow Silicones Corporation.

[0071] The amount of the hydrosilylation catalyst used herein will depend on a variety of factors, including the choice of the starting materials (D) polyorganohydrogensiloxane and (A) polydiorganosiloxane gum component, and the contents of their respective silicon-bonded hydrogen atoms (SiH) and aliphatic unsaturated groups, as well as the content of the platinum group metal in the selected catalyst. However, the amount of the hydrosilylation catalyst is sufficient to catalyze the hydrosilylation reaction of SiH and aliphatic unsaturated groups. Alternatively, based on the combined weight of the starting materials containing silicon-bonded hydrogen atoms and aliphatic unsaturated hydrocarbon groups, the amount of the catalyst is sufficient to provide 1 ppm to 6,000 ppm of the platinum group metal; alternatively, based on the same basis, 1 ppm to 1,000 ppm, or 1 ppm to 100 ppm of the platinum group metal. Alternatively, when the hydrosilylation catalyst comprises a platinum-organosiloxane complex, based on the combined weight of the starting materials (A) to (F) (e.g., the combined weight of all starting materials in the hydrosilylation-curable composition, excluding solvents), the amount of the hydrosilylation catalyst can be 0.01% to 5%.

[0072] (D) Polymethylhydrosiloxane

[0073] The starting material (D) in the hydrosilylation-curable composition is a unitary (R M 2 SiO 2 / 2 ) e (HR M SiO 2 / 2 ) f ,(R M 2 HSiO 1 / 2 ) g (R M 3 SiO 1 / 2 ) h of polyorganohydrogensiloxane; wherein R M As described above, the subscript e≥0, the subscript f≥0, the amount (e + f) is 4 to 500, the subscript g is 0, 1 or 2, the subscript h is 0, 1 or 2, the amount (g + h) = 2, and the amount (f + g)≥3. Alternatively, the amount (f + g) can be sufficient to provide a silicon-bonded hydrogen content of 0.5% to 2%, alternatively 0.6% to 1.5% for the polyorganohydrogensiloxane, and the silicon-bonded hydrogen (Si-H) content of the polyorganohydrogensiloxane can be determined by quantitative infrared analysis using ASTM E168.

[0074] Examples of suitable polyorganohydrogensiloxanes are:

[0075] (D-1) Bis-dimethylhydrogensilanyloxy-terminated poly(dimethyl / methylhydrogen)siloxane,

[0076] (D-2) Polymethylhydrogensiloxane endblocked with bis-dimethylhydrogensiloxy,

[0077] (D-3) Polydi-methyl / methylhydrogen)siloxane endblocked with bis-trimethylsilyloxy,

[0078] (D-4) Polymethylhydrogensiloxane endblocked with bis-trimethylsilyloxy, and

[0079] (D-5) A combination of two or more of (D-1), (D-2), (D-3) and (D-4). Methods for preparing polyorganohydrogensiloxanes, such as hydrolysis and condensation of organohydrogenhalosilanes, are well known in the art, see for example U.S. Patent 3,957,713 to Jeram et al. and U.S. Patent 4,329,273 to Hardman et al. Polyorganohydrogensiloxanes can also be prepared as described, for example, in U.S. Patent 2,823,218 to Speier et al., which discloses organohydrogensiloxane oligomers and linear polymers, such as 1,1,1,3,3-pentamethyldisiloxane; bis-trimethylsilyloxy endblocked polymethylhydrogensiloxane homopolymers; bis-trimethylsilyloxy endblocked poly(dimethyl / methylhydrogen)siloxane copolymers; and cyclic polymethylhydrogensiloxanes. Polyorganohydrogensiloxanes are also commercially available, for example those available from Gelest, Inc., Morrisville, Pennsylvania, USA, such as HMS-H271, HMS-071, HMS-993, HMS-301, HMS-301R, HMS-031, HMS-991, HMS-992, HMS-993, HMS-082, HMS-151, HMS-013, HMS-053, HAM-301, HPM-502 and HMS-HM271.

[0080] Based on the combined weight of starting materials (A) to (F), the amount of polyorganohydrogensiloxane in the hydrosilylation reaction curable composition is from 0.1% to 5%. Alternatively, the amount of polyorganohydrogensiloxane in the hydrosilylation reaction curable composition can be at least 0.1%, alternatively at least 0.25%, alternatively at least 0.3%; while, on the same basis, the amount can be at most 5%, alternatively at most 2.5%, alternatively at most 1.5%, alternatively at most 1%.

[0081] When relying on a hydrosilylation curing process, the ratio of silicon-bonded hydrogen to aliphatic unsaturated groups is important. Generally speaking, this is determined by calculating the total weight % of aliphatic unsaturated groups (such as vinyl) [V] in the composition and the total weight % of silicon-bonded hydrogen [H] in the composition. And assuming the molecular weight of hydrogen is 1 and the molecular weight of vinyl is 27, the molar ratio of silicon-bonded hydrogen to vinyl is 27[H] / [V]. The starting materials (A) polydiorganosiloxane gum component and (D) polyorganohydrogensiloxane can be present in the hydrosilylation reaction-curable composition in an amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms to aliphatic unsaturated hydrocarbon groups {(D):(A) ratio} of at least 20.8:1, alternatively at least 28.7:1, while this ratio can be at most 57.7:1, alternatively at most 54.7:1. Alternatively, the (D):(A) ratio can be from 20.8:1 to 57.7:1, alternatively from 28.7:1 to 54.7:1, alternatively from 20.8:1 to 28.8:1, alternatively from 28.7:1 to 57.7:1.

[0082] (E) Trialkyl borate

[0083] The starting material (E) in the hydrosilylation reaction-curable composition is a trialkyl borate of the formula B(OR A ) 3 where each R A is an alkyl group independently selected having from 1 to 30 carbon atoms, alternatively from 1 to 12 carbon atoms, alternatively from 1 to 6 carbon atoms. The alkyl group can be methyl, ethyl, propyl (e.g., isopropyl or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl or sec-butyl), pentyl (e.g., isopentyl, neopentyl or tert-pentyl), hexyl, a branched alkyl or cyclic alkyl group having 6 carbon atoms such as cyclopentyl or cyclohexyl. Examples of suitable trialkyl borates include trimethyl borate, triethyl borate, tributyl borate and combinations of two or more thereof. Alternatively, the trialkyl borate can be triethyl borate.

[0084] Trialkyl borates are known in the art and can be prepared by known methods (such as the method described in U.S. Patent 3,020,308 to Stange). Trialkyl borates are also commercially available. For example, triethyl borate can be obtained from Meryer(Shanghai)Chemical Technology Co.,Ltd., and trialkyl borate additives for silicone compositions are also known in the art, such as DOWSIL TM 7429PSA, which can be obtained from Dow Silicones Corporation.

[0085] Based on the combined weight of starting materials (A) to (F), the amount of (E) trialkyl borate added to the hydrosilylation-curable composition is from 0.05 wt% to 4.64 wt%. Alternatively, the amount of (E) trialkyl borate can be at least 0.05 wt%, alternatively at least 0.5 wt%, and alternatively at least 0.8%; meanwhile, on the same basis, the amount can be at most 4.64 wt%, alternatively at most 4 wt%, alternatively at most 2 wt%, alternatively at most 1.5 wt%, alternatively at most 1.0 wt%. Alternatively, on the same basis, the amount of (E) trialkyl borate can be from 0.5 wt% to 4.64 wt% and alternatively from 0.8 wt% to 4.64 wt%.

[0086] (F) Hydrosilylation inhibitor

[0087] Compared with a composition containing the same starting materials but omitting the inhibitor, starting material (F) is an optional hydrosilylation reaction inhibitor (inhibitor) that can be used to change the rate of the hydrosilylation reaction. Starting material (F) can be selected from the group consisting of: (F-1) alkynol, (F-2) silylated alkynol, (F-3) ene-yne compound, (F-4) triazole, (F-5) phosphine, (F-6) thiol, (F-7) hydrazine, (F-8) amine, (F-9) fumarate, (F-10) maleate, (F-11) ether, (F-12) carbon monoxide, (F-13) alkenyl-functionalized siloxane oligomer, and (F-14) a combination of two or more thereof. Alternatively, the hydrosilylation reaction inhibitor can be selected from the group consisting of: (F-1) alkynol, (F-2) silylated alkynol, (F-9) fumarate, (F-10) maleate, (F-13) carbon monoxide, (F-14) a combination of two or more thereof.

[0088] Examples of alkynols include: 3,5-dimethyl-1-hexyn-3-ol, 1-butyn-3-ol, 1-propyn-3-ol, 2-methyl-3-butyn-2-ol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3-phenyl-1-butyn-3-ol, 4-ethyl-1-octyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol and 1-ethynyl-1-cyclohexanol and combinations thereof. Alkynols are known in the art and are commercially available from various sources, see for example U.S. Patent 3,445,420 to Kookootsedes et al. Alternatively, the inhibitor can be a silylated acetylenic compound. Without wishing to be bound by theory, it is believed that the addition of a silylated acetylenic compound reduces the yellowing of the reaction product prepared by a hydrosilylation reaction as compared to the reaction product obtained by hydrosilylation of starting materials that do not contain a silylated acetylenic compound or contain an organic alkynol inhibitor (such as those described above). Examples of silylated acetylenic compounds include (3-methyl-1-butyn-3-oxy)trimethylsilane, ((1,1-dimethyl-2-propynyl)oxy)trimethylsilane, bis(3-methyl-1-butyn-3-oxy)dimethylsilane, bis(3-methyl-1-butyn-3-oxy)silane methylvinylsilane, bis((1,1-dimethyl-2-propynyl)oxy)dimethylsilane, methyl(tris(1,1-dimethyl-2-propynyloxy))silane, methyl(tris(3-methyl-1-butyn-3-oxy))silane, (3-methyl-1-butyn-3-oxy)dimethylphenylsilane, (3-methyl-1-butyn-3-oxy)dimethylhexenylsilane, (3-methyl-1-butyn-3-oxy)triethylsilane, bis(3-methyl-1-butyn-3-oxy)methyltrifluoropropylsilane, (3,5-dimethyl-1-hexyn-3-oxy)trimethylsilane, (3-phenyl-1-butyn-3-oxy)diphenylmethylsilane, (3-phenyl-1-butyn-3-oxy)dimethylphenylsilane, (3-phenyl-1-butyn-3-oxy)dimethylvinylsilane, (3-phenyl-1-butyn-3-oxy)dimethylhexenylsilane, (cyclohexyl-1-ethyn-1-oxy)dimethylhexenylsilane, (cyclohexyl-1-ethyn-1-oxy)dimethylvinylsilane, (cyclohexyl-1-ethyn-1-oxy)diphenylmethylsilane, (cyclohexyl-1-ethyn-1-oxy)trimethylsilane and combinations thereof. The silylated acetylenic compounds useful as inhibitors herein can be prepared by methods known in the art, for example, U.S. Patent 6,677,407 to Bilgrien et al. discloses the silylation of alkynols by reacting the alkynols described above with chlorosilanes in the presence of an acid acceptor.

[0089] Alternatively, the inhibitor can be an ene-yne compound such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne; and combinations thereof. Alternatively, the inhibitor can include triazole, examples being benzotriazole. Alternatively, the inhibitor can include phosphine. Alternatively, the inhibitor can include thiol. Alternatively, the inhibitor can include hydrazine. Alternatively, the inhibitor can include amine. Examples of amines are tetramethylethylenediamine, 3-dimethylamino-1-propyne, N-methylpropargylamine, propargylamine, 1-ethynylcyclohexylamine or combinations thereof. Alternatively, the inhibitor can include fumarate. Fumarates include dialkyl fumarates such as diethyl fumarate, diallyl fumarates such as diallyl fumarate, and dialkoxyalkyl fumarates such as bis(methoxymethyl)ethyl fumarate. Alternatively, the inhibitor can include maleate. Maleates include dialkyl maleates such as diethyl maleate, diallyl maleates such as diallyl maleate, and dialkoxyalkyl maleates such as bis(methoxymethyl)ethyl maleate. Alternatively, the inhibitor can include ether.

[0090] Alternatively, the inhibitor can include carbon monoxide. Alternatively, the inhibitor can include alkenyl-functionalized siloxane oligomers, which can be cyclic or linear, such as methylvinylcyclosiloxanes, examples being 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahydrohexenylcyclotetrasiloxane, 1,3-divinyl-1,3-diphenyl-1,3-dimethyldisiloxane; 1,3-divinyl-1,1,3,3-tetramethyldisiloxane; and combinations of two or more of them. Compounds that can be used as the above inhibitors can be commercially obtained, for example, from Sigma-Aldrich Inc. or Gelest, Inc., and are known in the art, for example, see U.S. Patent 3,989,667 granted to Lee et al. Examples of inhibitors suitable for use herein are those described as stabilizer E in paragraphs

[0148] to

[0165] of U.S. Patent Application Publication 2007 / 0099007.

[0091] The amount of the inhibitor will depend on various factors, including the desired pot life, whether the composition is a one-part composition or a multi-part composition, the specific inhibitor used, and the choice and amount of the (C) hydrosilylation reaction catalyst. However, when present, based on the combined weight of the starting materials (A) to (F) in the hydrosilylation reaction-curable composition, the amount of the (F) inhibitor can be in the range of 0% to 5%, alternatively 0% to 1%, alternatively 0.001% to 1%, alternatively 0.01% to 0.5%, and alternatively 0.0025% to 0.025%.

[0092] (G) Solvent

[0093] The hydrosilylation-curable composition further comprises a starting material (G), a solvent. The solvent can be an organic solvent such as a hydrocarbon, a ketone, an acetate, an ether, and / or a cyclic siloxane having an average degree of polymerization of 3 to 10. The hydrocarbon suitable for the solvent can be (G-1) an aromatic hydrocarbon such as benzene, toluene, or xylene; (G-2) an aliphatic hydrocarbon such as hexane, heptane, octane, or isoparaffin; or (G-3) a combination thereof. Alternatively, the solvent can be a glycol ether such as propylene glycol methyl ether, dipropylene glycol methyl ether, or propylene glycol n-butyl ether. Suitable ketones include acetone, methyl ethyl ketone, or methyl isobutyl ketone. Suitable acetates include ethyl acetate or isobutyl acetate. Suitable ethers include diisopropyl ether or 1,4-dioxolane. Suitable cyclic siloxanes having a degree of polymerization from 3 to 10, alternatively 3 to 6, include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and / or decamethylcyclopentasiloxane. Alternatively, the solvent can be selected from the group consisting of benzene, toluene, xylene, heptane, ethylbenzene, ethyl acetate, and combinations of two or more thereof.

[0094] The amount of the solvent will depend on various factors, including the type of the solvent selected and the amounts and types of other starting materials selected for the hydrosilylation-curable composition. However, based on the combined weight of all the starting materials in the hydrosilylation-curable composition, the amount of the solvent can range from >0% to 90%, alternatively 0% to 60%, alternatively 20% to 60%, alternatively 45% to 65%, and alternatively 50% to 60%. The solvent can be added during the preparation of the hydrosilylation-curable composition, for example, to assist in mixing and delivering one or more of the above-mentioned starting materials. All or a part of the solvent can be added together with one or more of the other starting materials. For example, the polyorganosilicate resin and / or the hydrosilylation catalyst can be dissolved in the solvent before being combined with the other starting materials in the hydrosilylation-curable composition. All or a part of the solvent can be optionally removed after the preparation of the hydrosilylation-curable composition.

[0095] (H) Fixing additive

[0096] The starting material (H) in the hydrosilylation-curable composition is an adhesion promoter. Without wishing to be bound by theory, it is believed that the adhesion promoter will enhance the adhesion to the substrate by means of the silicone pressure-sensitive adhesive prepared by curing the hydrosilylation-curable composition described herein.

[0097] Suitable anchoring additives for the starting material (H) include silane coupling agents such as methyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, bis(trimethoxysilyl)propane and bis(trimethoxysilyl)hexane; and mixtures or reaction mixtures of said silane coupling agents. Alternatively, the anchoring additive may be tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, allyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, or 3-methacryloxypropyltrimethoxysilane.

[0098] Examples of other suitable anchoring additives are reaction products of vinylalkoxysilanes with epoxy-functionalized alkoxysilanes; reaction products of vinylacetoxysilanes with epoxy-functionalized alkoxysilanes; and combinations (e.g., physical blends and / or reaction products) of polyorganosiloxanes having at least one aliphatic unsaturated hydrocarbon group and at least one hydrolysable group per molecule with epoxy-functionalized alkoxysilanes (e.g., combinations of hydroxy-terminated vinyl-functionalized polydimethylsiloxane with glycidoxypropyltrimethoxysilane).

[0099] Exemplary anchoring additives are known in the art, such as U.S. Patent 9,562,149, U.S. Patent Application Publication No. 2003 / 0088042, U.S. Patent Application Publication No. 2004 / 0254274, U.S. Patent Application Publication No. 2005 / 0038188, U.S. Patent Publication 2012 / 0328863, paragraph

[0091] , and U.S. Patent Publication 2017 / 0233612, paragraph

[0041] ; and European Patent 0 556 023. Anchoring additives are commercially available. For example, SYL-OFF TM 9250, SYL-OFF TM 9176, SYL-OFF TM 297 and SYL-OFF TM 397 are available from Dow Silicones Corporation, Midland, Michigan, USA. Other exemplary anchoring additives include (G-1) vinyltriacetoxysilane, (G-2) glycidoxypropyltrimethoxysilane, and (G-3) a combination of (G-1) and (G-2). This combination (G-3) can be a mixture and / or reaction product.

[0100] The amount of the anchoring additive depends on a variety of factors, including the type of substrate to which the organosilicon pressure-sensitive adhesive will adhere. However, when present, based on the combined weight of all starting materials in the hydrosilylation-curable composition that do not include a solvent, the amount of the anchoring additive can be from 0.5% to 5%, alternatively from 0.5% to 3%, and alternatively from 0.5% to 2.5%.

[0101] Method for preparing a hydrosilylation-curable composition

[0102] The hydrosilylation-curable composition can be prepared by a method including the following process: combining all of the starting materials as described above by any convenient means (such as mixing at room temperature or elevated temperature). For example, when the hydrosilylation-curable composition will be prepared at an elevated temperature and / or the hydrosilylation-curable composition will be prepared as a one-part composition, the hydrosilylation inhibitor can be added before the hydrosilylation catalyst.

[0103] The method can also include delivering one or more starting materials (e.g., the hydrosilylation catalyst and / or the polyorganosilicate resin) in a solvent, which one or more starting materials can be dissolved in the solvent when combined with one or more other starting materials in the hydrosilylation-curable composition. Those skilled in the art will understand that if it is desired that the resulting hydrosilylation-curable composition will be solvent-free (i.e., will not contain a solvent or may contain trace residual solvents from the delivery of the starting materials), the solvent can be removed after combining two or more of the starting materials, and in such a case, no solvent will be intentionally added to the hydrosilylation-curable composition.

[0104] Alternatively, for example, when the hydrosilylation-curable composition will be stored for a longer time before use, such as up to 6 hours before applying the hydrosilylation-curable composition to an optical organosilicon elastomer or other substrate, the hydrosilylation-curable composition can be prepared as a multi-part composition. In the multi-part composition, the hydrosilylation catalyst is stored in a part separate from any starting material having a silicon-bonded hydrogen atom (such as a polyorganohydrogensiloxane), and the parts are combined immediately before using the hydrosilylation-curable composition.

[0105] For example, a multi-part composition can be prepared by the following process: combining starting materials comprising at least some of a polydiorganosiloxane gum component, a polyorganohydrogensiloxane, and optionally one or more of the other starting materials described above (other than the hydrosilylation catalyst) in any convenient manner, such as by mixing, to form a base portion. A curing agent can be prepared by combining starting materials comprising at least some of the following in any convenient manner, such as by mixing: a polydiorganosiloxane gum, a hydrosilylation catalyst, and optionally one or more of the other starting materials described above (other than the polyorganohydrogensiloxane). The starting materials can be mixed at ambient temperature or elevated temperature. A hydrosilylation inhibitor can be included in one or more of the base portion, the curing agent portion, or a separate additional portion. A polyorganosilicate resin can be added to the base portion, the curing agent portion, or a separate additional portion. Alternatively, the polyorganosilicate resin can be added to the base portion. A solvent can be added to the base portion. Alternatively, starting materials comprising some or all of the polyorganosilicate resin and the solvent can be added in a separate additional portion. When using a two-part composition, the weight ratio of the amount of the base portion to the amount of the curing agent portion can be in the range of 1:1 to 10:1. The hydrosilylation curable composition will cure via a hydrosilylation reaction to form a silicone pressure-sensitive adhesive.

[0106] Method of use

[0107] The above method can further include one or more additional steps. The hydrosilylation curable composition prepared as described above can be used to form an adhesive article on a substrate, such as a silicone pressure-sensitive adhesive (prepared by curing the hydrosilylation curable composition as described above). Accordingly, the method can further include applying the hydrosilylation curable composition to a substrate.

[0108] The hydrosilylation curable composition can be applied to the substrate by any convenient manner. For example, the hydrosilylation curable composition is applied to the substrate by a gravure coater, a comma coater, an offset coater, an offset gravure coater, a roll coater, a reverse roll coater, an air knife coater, a curtain coater, or a slot die.

[0109] The substrate can be any material that can withstand the curing conditions (described below) for curing the hydrosilylation-reaction curable composition to form a silicone pressure-sensitive adhesive on the substrate. For example, any substrate that can withstand heat treatment at a temperature equal to or greater than 120 °C, alternatively 150 °C, is suitable. Examples of materials suitable for such substrates include polymer films such as polyimide (PI), polyetheretherketone (PEEK), polyethylene naphthalate (PEN), liquid crystal polyarylate, polyamideimide (PAI), polyethersulfide (PES), polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU), polyethylene (PE) or polypropylene (PP). Alternatively, the substrate can be glass. Alternatively, for example, when the silicone pressure-sensitive adhesive is to be used in a dry-casting method, the substrate can be a release liner. The thickness of the substrate is not critical; however, the thickness can be from 5 μm to 300 μm, alternatively 10 μm to 200 μm. Alternatively, the substrate can be selected from the group consisting of PI, PET, TPU, PMMA, and optical silicone elastomers.

[0110] Optical silicone elastomers are known in the art and are described, for example, in U.S. Patent 8,859,693 to Hasegawa et al. and U.S. Patent 8,853,332 to Akitomo et al. Optical silicone elastomers are commercially available. For example, the optical silicone elastomers SILASTIC TM MS-1001, MS-1002, MS-1003, and MS-4002, as well as MS-4007, are moldable optical silicone elastomers, and SYLGARD TM 182, 184, and 186 are other optical silicone elastomers, all of which are commercially available from Dow Silicones Corporation, Midland, Michigan, USA.

[0111] To improve the adhesion of the silicone pressure-sensitive adhesive to the substrate, the method for forming the adhesive article can also optionally include treating the substrate prior to applying the hydrosilylation-reaction curable composition. Treating the substrate can be carried out by any convenient means, such as applying a primer, or subjecting the substrate to corona discharge treatment, etching, or plasma treatment prior to applying the hydrosilylation-reaction curable composition to the substrate.

[0112] The method described herein may optionally further include applying a removable release liner to the silicone pressure-sensitive adhesive opposite the substrate, e.g., to protect the silicone pressure-sensitive adhesive before using the adhesive article. The release liner may be applied before, during, or after curing the hydrosilylation reaction curable composition; alternatively, it may be applied after curing. The adhesive article may be a component for a flexible display device, such as an optical component.

[0113] Use of an organosilicon pressure-sensitive adhesive in components of a flexible display device

[0114] Figure 1 A partial cross-section of a flexible display device component (100) is shown. The component (100) includes a silicone pressure-sensitive adhesive (102) having a surface (102a) and an opposite surface (102b). The opposite surface (102b) of the silicone pressure-sensitive adhesive (102) adheres to the surface (103a) of the optical silicone elastomer (103) with a peel adhesion of >500 g / in, as measured by the test method described in the following examples. The silicone pressure-sensitive adhesive (102) may have a thickness of 10 μm to 200 μm. The silicone pressure-sensitive adhesive (102) adheres to a substrate (101) having a surface (101a) and an opposite surface (101b). The surface (102a) of the silicone pressure-sensitive adhesive (102) contacts the opposite surface (101b) of the substrate (101). The substrate (101) may be selected from the group consisting of PI, PET, TPU, PMMA, and optical silicone rubber (which may be the same as or different from the optical silicone rubber (103)) and may have a thickness of 10 μm to 200 μm.

[0115] The above hydrosilylation reaction curable composition and method can be used to fabricate the flexible display device component (100) via wet casting. For example, the hydrosilylation reaction curable composition can be applied to the opposite surface (101b) of the substrate (101) and cured to form the silicone pressure-sensitive adhesive (102). Alternatively, the hydrosilylation reaction curable composition described herein can be applied to the surface (103a) of the optical silicone elastomer (103) and cured to form the silicone pressure-sensitive adhesive (102). Alternatively, the hydrosilylation reaction curable composition can be applied to the surface of a release liner and cured to form the silicone pressure-sensitive adhesive (102). Thereafter, the optical silicone rubber (103) can be brought into contact with the opposite surface (102b) of the silicone pressure-sensitive adhesive (102), and the substrate (101) can be brought into contact with the surface (102a) of the silicone pressure-sensitive adhesive (102).

[0116] Examples

[0117] The following examples are provided to illustrate the present invention to those skilled in the art, and these examples should not be construed as limiting the present invention as set forth in the claims. The starting materials used herein are described in Table 1.

[0118] Table 1 - Starting materials

[0119]

[0120]

[0121] In Table 1, the starting materials with the trademarks DOWSIL TM , SILASTIC TM and SYL-OFF TM are commercially available from Dow Silicones Corporation.

[0122] In this Reference Example 1, samples of the hydrosilylation-curable composition were prepared using the starting materials and amounts shown in Table 2 below. Unless otherwise specified, the amounts are in parts by weight. The starting material (A) polydiorganosiloxane gum component and the starting material (B) polyorganosilicate resin component were dissolved in the (G) solvent under mixing until the resulting mixture was homogeneous. Then the starting material (F) hydrosilylation inhibitor was thoroughly blended into the above mixture. And then the starting material (E) trialkyl borate was thoroughly blended into the above mixture. And then the starting material (D) polyorganohydrogensiloxane was thoroughly blended into the above mixture. And optionally then the starting material (H) anchoring additive (if used) was thoroughly blended into the above mixture. Finally, the starting material (C) hydrosilylation catalyst was added and mixed until homogeneous. All starting materials were mixed at RT. The starting materials and their amounts (by weight) are shown in Table 2 below.

[0123] Table 2 - Hydrosilylation-curable compositions

[0124]

[0125]

[0126] The hydrosilylation-curable composition in Table 2 contains a small amount of Residual Solvent 1 introduced together with the starting materials.

[0127] Before applying the hydrosilylation-curable composition to a substrate, DOWSIL TM7499 PSA primer was applied to the substrate to a thickness sufficient to provide a dry coating weight of 0.20 gsm after heating in an oven at 120 °C for 0.5 minutes. The primer layer on the substrate provided sufficient adhesion between the substrate and the cured silicone pressure-sensitive adhesive. In this Reference Example 2, the hydrosilylation reaction-curable composition was applied to the substrate and cured according to the following procedure. Each sample prepared as described above was applied to a 50-μm-thick PET film to a thickness sufficient to provide a dry coating weight of 50 μm after heating in an oven at 140 °C for 2 minutes. After curing, the strip samples were cut into 1-inch widths for the peel adhesion test in the following steps.

[0128] The resulting strip samples were applied to the substrate such that the silicone pressure-sensitive adhesive contacted the substrate. The substrates were SUS and Si rubber B, and after the silicone pressure-sensitive adhesive was brought into contact with the substrate, the samples were held at RT for 20 minutes and then tested. The test was repeated, but the samples were held at 70 °C for 1 day before testing.

[0129] Table 3 - Calculated and measured values for hydrosilylation-curable compositions

[0130]

[0131]

[0132] In this Reference Example 3, the samples prepared as described in Reference Example 2 were tested as follows. The adhesion of each strip sample prepared as described above to the SUS and Si rubber B substrates was tested by peeling each strip from the substrate and checking for any transfer of the silicone pressure-sensitive adhesive from the PET film to the substrate. An adhesion / peel tester AR-1500 was used. The width of each PET sheet was 1 inch. The peel rate and peel angle were 0.3 m / min and 180°, respectively. The unit was grams per inch. The results are shown in Table 4 below.

[0133] The adhesion test method for SUS refers to the test standard ASTM D3330. The stainless steel plate was cleaned with a solvent. The strip sample (1-inch wide) was applied to the stainless steel plate. It was rolled twice in each direction at a speed of 10 mm / s with a standard 2-kg test roller. After a 20-minute pressure holding time, the sample was peeled from the steel plate at a peel angle of 180° at a rate of 300 mm / min using the AR-1500.

[0134] The adhesion test method for silicone rubber B refers to the test standard ASTM D3330. Clean the silicone rubber sheet with a solvent. Apply the tape sample (1 inch wide, i.e., 25.4 mm) to the silicone rubber sheet. Roll the standard 2 kg test roller at a speed of 10 mm / s in each direction twice. After a 20-minute pressure holding time, use an AR-1500 to peel the sample from the silicone rubber sheet at a peeling angle of 180° at a rate of 300 mm / min.

[0135] The adhesion test method for silicone rubber (70°C - 1 day) refers to the test standard ASTM D3330. Clean the silicone rubber sheet with a solvent. Apply the tape sample (1 inch wide, i.e., 25.4 mm) to the silicone rubber sheet. Roll the standard 2 kg test roller at a speed of 10 mm / s in each direction twice. After aging the sample at 70°C for one day (24 hours), use an AR-1500 to peel the sample from the silicone rubber sheet at a peeling angle of 180° at a rate of 300 mm / min.

[0136] The test method for rheological data (Tg, G' at -20°C, 25°C, and 100°C) refers to the test standard ASTM D4440-15.

[0137] Prepare cured pure silicone pressure-sensitive adhesive films (without substrate) each with a thickness of 0.5 mm - 1.5 mm for rheological property testing on a rheometer TA DHR-2 or ARES-G2 on parallel plates with a diameter of 8 mm. Measure the loss modulus G'' and storage modulus G' at different temperatures (i.e., 200°C to -80°C) in oscillatory mode at 1 Hz with a cooling rate of 3°C / min and a strain of 0.25% through a temperature ramp program. Calculate tanδ by G'' / G'. The glass transition temperature is defined as the temperature at the peak point of tanδ. The results are shown in Table 4 below.

[0138] Table 4 - Results

[0139] Samples Comparative Example 1 Comparative Example 2 Comparative Example 3 Working Example 1 Working Example 2 Working Example 3 Working Example 4 On SUS (RT - 20 min) 2175.0 1362.9 1040.7 1510.0 883.7 1498.2 578.8 On Si rubber B (RT - 20 min) 380.5 314.4 240.3 744.0 713.5 504.1 958.7 On Si rubber B (70 °C - 1 d) 613.2 490.5 474.4 1238 1198 865 1500.8 Tg (°C) 9.9 -4.86 -8.80 -7.60 -8.14 -2.10 -62.20 G’ (-20 °C) (kPa) 920.2 783.2 550.0 690.0 510.0 852.0 39.0 G’ (25 °C) (kPa) 51.04 37.4 29.5 35.1 32.8 42.5 31.0 G’ (100 °C) (kPa) 20.1 21.5 22.3 25.6 22.13 21.1 28.6

[0140] Industrial applications

[0141] The above examples show that a hydrosilylation reaction curable composition can be prepared which cures to form a silicone pressure sensitive adhesive having desired adhesive properties: adhesion to stainless steel > 500 g / inch, adhesion to an optical silicone elastomer at RT > 500 g / inch, and adhesion to an optical silicone elastomer after aging the silicone pressure sensitive adhesive on an optical silicone rubber at 70 °C for one day > 800 g / inch. The high adhesion makes the interface between the silicone pressure sensitive adhesive and the substrate (adherend) strong enough to resist delamination in repeated deformation tests (e.g., by folding, bending, rolling or stretching tests) of a flexible display device. The silicone pressure sensitive adhesive may also have a Tg ≤ 0 °C, G' < 1 MPa at -20 °C, G' < 50 kPa at 25 °C, and G' < 50 kPa at 100 °C. The low Tg and low G' over a wide temperature range make the silicone pressure sensitive adhesive suitable for use over a wide temperature range with lower stress applied to other layers during repeated deformation tests (e.g., by folding, bending, rolling and stretching tests). This combination of properties makes the silicone pressure sensitive adhesive suitable for flexible display devices, particularly the optical components of flexible display devices. Due to the excellent properties of the silicone elastomer to resist repeated folding, bending, rolling and stretching, the combination of the silicone pressure sensitive adhesive prepared as described herein with an optical silicone elastomer results in excellent reliability testing of articles for flexible display devices when subjected to repeated deformation tests (e.g., folding, bending, rolling and stretching tests).

[0142] Definition and use of terms

[0143] Unless otherwise indicated, all amounts, ratios and percentages herein are by weight. The Summary of the Invention and the Abstract of the Disclosure are hereby incorporated by reference. Unless the context of this specification otherwise indicates, the articles "a", "an" and "the" each refer to one or more. The transitional phrases "comprising", "consisting essentially of" and "consisting of" are used as described in Chapters §2111.03I., II. and III of the Ninth Edition of the Manual of Patent Examining Procedure (Patent Examining Procedure Ninth Edition), last revised in January 2018, Revision 08.2017. The use of "for example", "for instance", "such as" and "including" to list exemplary examples does not mean limitation to the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to" and encompasses other similar or equivalent examples. The abbreviations used herein have the definitions in Table 5.

[0144] Table 5 - Abbreviations

[0145]

[0146]

[0147] The present invention has been described by way of example, and it should be understood that the terms used are intended to be of a descriptive rather than limiting nature. With respect to any Markush group relied upon herein to describe a particular feature or aspect, different, special, and / or unexpected results can be obtained from each member of the corresponding Markush group independent of all other Markush members. Each member of the Markush group can be relied upon individually and / or in combination and provides adequate support for specific embodiments within the scope of the appended claims.

[0148] In addition, any ranges and sub-ranges relied upon in describing the present invention fall independently and jointly within the scope of the appended claims, and it should be understood that all ranges are described and contemplated as including all and / or part of the values therein, even if such values are not explicitly written herein. Those skilled in the art will readily recognize that the recited ranges and sub-ranges fully describe the various embodiments of the present invention and render them possible, and such ranges and sub-ranges can be further delineated into related one-half, one-third, one-fourth, one-fifth, and any other sub-ranges contained within the range. Merely by way of example, the range of "0.05 to 4.64" for the amount of trialkyl borate can be further delineated into the lower one-third, i.e., "0.05 to 1.58", the middle one-third, i.e., "1.59 to 3.11", and the upper one-third, i.e., "3.12 to 4.64", and alternatively, the range "0.05 to 4.64" includes the sub-ranges "0.05 to 0.98", "0.78 to 0.98", and "0.98 to 4.64" as well as the individual values 0.05, 0.78, 0.98, and 4.64, each of which individually and jointly falls within the scope of the appended claims and can be relied upon individually and / or in combination and provides adequate support for specific embodiments within the scope of the appended claims. Further, with respect to language that defines or modifies a range, such as "at least", "greater than", "less than", "not exceeding", etc., it should be understood that such language includes sub-ranges and / or upper or lower limits.

Claims

1. A hydrosilylation-curable composition for forming a silicone pressure-sensitive adhesive, wherein the composition comprises: (A) A polydiorganosiloxane gum component, which comprises Based on the combined weight of starting materials (A) to (F), 32.2% to 44.6% by weight of the unitary (R M 2 R U SiO 1 / 2 ) 2 (R M 2 SiO 2 / 2 ) a of the (A-1) aliphatically unsaturated polydiorganosiloxane gum, wherein each R M is a monovalent hydrocarbon group independently selected having 1 to 30 carbon atoms and free of aliphatic unsaturated groups; each R U is a monovalent aliphatically unsaturated hydrocarbon group independently selected having 2 to 30 carbon atoms; and the subscript a has a value sufficient to impart a plasticity of 20 mils (0.51 mm) to 80 mils (2.03 mm) to the polydiorganosiloxane gum, wherein the plasticity is measured based on ASTM D926 by applying a 1 kg load to a spherical sample weighing 4.2 g at 25 °C for 3 minutes, and the result is measured in thousandths of an inch (mils), and the procedure is based on ASTM D926, and 0% to <1.2% by weight of the unitary ((HO)R M 2 SiO 1 / 2 ) 2 (R M 2 SiO 2 / 2 ) a’ of the (A-2) hydroxyl-terminated polydiorganosiloxane gum, wherein each R M is a monovalent hydrocarbon group independently selected having 1 to 30 carbon atoms and free of aliphatic unsaturated groups; each subscript a' has a value sufficient to impart a plasticity of 20 mils (0.51 mm) to 80 mils (2.03 mm) to the polydiorganosiloxane gum; and Provided that the weight ratio of (A-1) the aliphatically unsaturated polydiorganosiloxane gum : (A-2) the hydroxyl-terminated polydiorganosiloxane gum ≥ 37.4:1; (B) A polyorganosilicate resin component, which comprises Based on the combined weight of starting materials (A) to (F), 44.8 wt% to 58.9 wt% of the unitary: (R M 3 SiO 1 / 2 ) z (SiO 4 / 2 ) o Z p -capped resin, where Z is a hydrolyzable group, the subscript p is a value from 0 to sufficient to give the capped resin a hydrolyzable group content of at most 2%, and the values of the subscripts z and o are such that z > 4, o > 1, and the quantity (z + o) has a value sufficient to provide the capped resin with a number average molecular weight of 500 g / mol to 2,700 g / mol; and Based on the combined weight of starting materials (A) to (F), 0 wt% to 7 wt% of the unitary (R M 3 SiO 1 / 2 ) z’ (SiO 4 / 2 ) o’ Z p’ of the (B-2) uncapped resin, where the subscript p’ has a value sufficient to impart a hydrolyzable group content of >3% to 10% to the uncapped resin, the values of the subscripts z’ and o’ are such that z’ > 4, o’ > 1, and the amount (z’ + o’) has a value sufficient to provide a number average molecular weight of 500 g / mol to 5,000 g / mol to the uncapped resin, where based on the combined weight of starting materials (A) to (F), (B-1) the capped resin and (B-2) the uncapped resin are present in a combined amount of 44.8 wt% to 65.8 wt%, provided that the weight ratio of (B-2) the uncapped resin:(B-1) the capped resin is 0.032:1 to 0.125:1; wherein (A) the polydiorganosiloxane gum component and (B) the polyorganosilicate resin component are present in a weight ratio of (B):(A) ≤ 2.0:1; 0.01% to 5% by weight of (C) a hydrosilylation catalyst, based on the combined weight of starting materials (A) to (F); Based on the combined weight of starting materials (A) to (F), 0.1% to 5% by weight of (D) units of the formula: (R M 2 SiO 2 / 2 ) e (HR M SiO 2 / 2 ) f (R M 2 HSiO 1 / 2 ) g (R M 3 SiO 1 / 2 ) h of a polyorganohydrogensiloxane; wherein the subscript e ≥ 0, the subscript f ≥ 0, the quantity (e + f) is from 4 to 500, the subscript g is 0, 1 or 2, the subscript h is 0, 1 or 2, the quantity (g + h) = 2, and the quantity (f + g) ≥ 3; wherein (D) the polyorganohydrogensiloxane is present in an amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms to aliphatically unsaturated hydrocarbon groups of the polydiorganosiloxane gum component (A) of from 20.8:1 to 57.7:1; 0.05% to 4.64% by weight of (E) a trialkyl borate, based on the combined weight of starting materials (A) to (F); 0% to 5% by weight of (F) a hydrosilylation inhibitor, based on the combined weight of starting materials (A) to (F); >0% to 90% by weight of (G) a solvent, based on the combined weight of all starting materials in the composition; and 0% to 5% by weight of (H) an anchoring additive, based on the combined weight of starting materials (A) to (F).

2. The composition according to claim 1, wherein in component (A), the polydiorganosiloxane gum, each R M is independently selected from alkyl groups having 1 to 6 carbon atoms; and Each R U is independently selected from the group consisting of vinyl, allyl, and hexenyl; and the subscript a is sufficient to provide a plasticity value of from 30 mils (0.76 mm) to 70 mils (1.778 mm).

3. The composition according to claim 1, wherein in component (B), the polyorganosilicate resin, each R M is independently selected from alkyl groups having 1 to 6 carbon atoms; and Each Z is OH.

4. The composition according to claim 1, wherein (C) the hydrosilylation catalyst comprises a Karstedt catalyst.

5. The composition according to claim 1, wherein in the polyorganohydrogensiloxane (D), each R M is an independently selected alkyl group having 1 to 6 carbon atoms, subscript g = 0, and subscript h = 2.

6. The composition according to claim 1, wherein (E) the trialkyl borate comprises triethyl borate.

7. The composition according to claim 1, wherein the composition is a multi-part composition comprising a base part and a curing agent part, wherein the base part comprises starting materials A) and C); and the curing agent part comprises starting materials A) and D); and the composition further comprises starting materials B), E) and F) in one or more of the base part, the curing agent part or a separate additional part.

8. A wet casting method, the wet casting method comprising 1) applying the composition according to claim 1 to a substrate, and 2) curing the composition to form the silicone pressure-sensitive adhesive on the substrate.

9. A dry casting method, the dry casting method comprising 1) applying the composition according to claim 1 to a release liner, 2) curing the composition to form the silicone pressure-sensitive adhesive on the release liner, and 3) applying the silicone pressure-sensitive adhesive to a substrate.

10. The method according to claim 8 or claim 9, wherein the substrate is an optical silicone elastomer.

11. The method according to claim 8 or claim 9, wherein the silicone pressure-sensitive adhesive is optically transparent.

12. An article prepared by the method according to claim 8 or claim 9.

13. The article according to claim 12, wherein the article is part of a flexible display device.

14. A component of a flexible display device, the component comprising: I) an optical silicone elastomer layer, and II) A silicone pressure-sensitive adhesive layer adhered to the optical silicone elastomer layer, wherein the silicone pressure-sensitive adhesive layer is a product of the composition according to any one of claims 1 to 5.

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