Polyorganosiloxane release coatings, their preparation and use
阅读说明：本技术 聚有机硅氧烷防粘涂层及其制备和用途 (Polyorganosiloxane release coatings, their preparation and use ) 是由 黄福明 田中英文 西嶋一裕 张胜蓝 刘志华 于 2019-05-21 设计创作，主要内容包括：本发明提供了一种可固化聚有机硅氧烷防粘涂料组合物,该可固化聚有机硅氧烷防粘涂料组合物包含：A)支链脂族不饱和聚有机硅氧烷,B)每分子具有至少3个硅键合的氢原子的交联剂,C)硅氢加成反应催化剂,D)硅氢加成反应抑制剂,以及E)具有一定含量的脂族不饱和基团的芳基官能化聚二有机硅氧烷。还提供了具有该涂层(101)的防粘衬垫(100)及其制备方法。(The present invention provides a curable polyorganosiloxane release coating composition comprising: A) a branched aliphatic unsaturated polyorganosiloxane, B) a crosslinking agent having at least 3 silicon-bonded hydrogen atoms per molecule, C) a hydrosilylation reaction catalyst, D) a hydrosilylation reaction inhibitor, and E) an aryl-functionalized polydiorganosiloxane having a content of aliphatic unsaturated groups. A release liner (100) having the coating (101) and a method of making the same are also provided.)
1. A curable polyorganosiloxane release coating composition comprising:
A) a branched, aliphatically unsaturated polyorganosiloxane,
B) a crosslinking agent having at least 3 silicon-bonded hydrogen atoms per molecule,
C) a hydrosilylation reaction catalyst in an amount sufficient to provide from 1ppm to 500ppm by weight of a platinum group metal based on the combined weight of starting materials A), B), C), D), and E),
D) a hydrosilylation reaction inhibitor in an amount of 0.001% to 5% based on the combined weight of starting materials A), B), C), D), and E), and
E) an aryl-functionalized polydiorganosiloxane having aliphatic unsaturation in an amount > 0.06% and < 0.24%, wherein starting material E) is present in an amount > 0% to 1% based on the combined weight of starting materials A), B), C), D), and E); and is
Wherein all starting materials are present in an amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms to aliphatic unsaturation (overall SiH: Vi ratio) of >1.35:1 to <1.9:1 in the release coating composition.
2. The composition according to claim 1, further comprising one or more additional starting materials selected from the group consisting of F) anchorage additives, G) solvents, and H) anti-fog additives.
3. The composition of claim 1, wherein the branched aliphatic unsaturated polyorganosiloxane is selected from the group consisting of:
unit formula (A-1) (R)1 3SiO1/2)a(R2R1 2SiO1/2)b(R1 2SiO2/2)c(SiO4/2)dWherein each R is1Independently a monovalent hydrocarbon group free of aliphatic unsaturation, and each R2Is an aliphatic unsaturated hydrocarbon group, wherein subscript a is 0 or more and subscript b>0, subscript c is 15 to 995, and subscript d>0；
Unit formula (A-2) (R)1 3SiO1/2)e(R2R1 2SiO1/2)f(R1 2SiO2/2)g(R1SiO3/2)hWherein subscript e is not less than 0Mark f>0, subscript g is 15 to 995, and subscript h>0; and
a combination of both (A-1) and (A-2).
4. The composition of claim 3, wherein 22. gtoreq.a.gtoreq.0, 22. gtoreq.b >0, 995. gtoreq.c.gtoreq.15, 10. gtoreq.d >0, 12. gtoreq.0, 12. gtoreq.f >0, 995. gtoreq.g.gtoreq.15, and 10. gtoreq.h >0.
5. The composition of claim 3, wherein each R1Is an alkyl group of 1 to 6 carbon atoms (alternatively methyl), and each R2Is an alkenyl group of 2 to 6 carbon atoms (alternatively vinyl, allyl or hexenyl).
6. The composition of claim 1, wherein the crosslinker has the unit formula (B-1): (R)1 3SiO1/2)2(R1 2SiO2/2)k(R1HSiO2/2)mWherein each R is1Independently selected from the group consisting of monovalent hydrocarbon groups free of aliphatic unsaturation and monovalent halogenated hydrocarbon groups free of aliphatic unsaturation, subscript k ≧ 0, subscript m>0, and the amount (m + k) is 8 to 400.
7. The composition of claim 6, wherein each R1Is an alkyl group of 1 to 6 carbon atoms (alternatively methyl).
8. The composition of claim 1, wherein the platinum group metal catalyst is selected from the group consisting of: (C-1) a metal selected from the group consisting of platinum, rhodium, ruthenium, palladium, osmium and iridium; (C-2) a compound of said metal (C-1), (C-3) a complex of said compound (C-2) with an organopolysiloxane, and (C-4) said compound (C-2) microencapsulated in a matrix or core/shell type structure.
9. The composition of claim 1, wherein the hydrosilylation reaction inhibitor is selected from the group consisting of a combination of two or more of (D-1) alkynols, (D-2) silylated acetylenic compounds, (D-3) cycloalkenylsiloxanes, (D-4) ene-yne compounds, (D-5) triazoles, (D-6) phosphines, (D-7) thiols, (D-8) hydrazines, (D-9) amines, (D-10) fumarates, (D-11) maleates, (D-12) nitriles, (D-13) ethers, and (D-14) (D-1) to (D-13).
10. The composition of claim 1 wherein the aryl-functionalized polydiorganosiloxane has the unit formula: (R)3 3SiO1/2)r(R3 2R4SiO1/2)s(R3 2R5SiO1/2)t(R3 2SiO2/2)u(R3R4SiO2/2)v(R3R5SiO2/2)w(R4 2SiO2/2)xWherein each R is3Is an independently selected alkyl group, each R4Is an independently selected aryl group, each R5Independently selected from alkenyl and alkynyl, subscript r is greater than or equal to 0, subscript s is greater than or equal to 0, subscript t is greater than or equal to 0, subscript u is greater than or equal to 0, subscript w is greater than or equal to 0, subscript x is greater than or equal to 0, and the amount (r + s + t) is 2, the amount (t + w) being sufficient to provide the aryl-functionalized polydiorganosiloxane in an amount of>0.06% to<0.24% of aliphatically unsaturated groups, amount (s + v + x)>0, and the amount (r + s + t + u + v + w + x) ≥ 3.
11. The composition of claim 10, wherein the aryl-functionalized polydiorganosiloxane has the unit formula: (R)3 3SiO1/2)2(R3 2SiO2/2)u(R3R4SiO2/2)v(R3R5SiO2/2)w(R4 2SiO2/2)xWherein u is 0-1,000, v is 0-120, 0<w ≦ 4, 0 ≦ x ≦ 26, and the value of the amount (v + x) is sufficient to provide the aryl-functionalized polydiorganosiloxane with a content of 0.07% to 0.21%, alternatively 0.08% to 0.19%, alternatively 0.09% to 0.16%, alternatively 0.10% to 0.14%, additionallyOptionally 0.11% to 0.13%, and alternatively 0.12% of aliphatic unsaturation.
12. The composition of claim 2 wherein F) the anchor additive is present and is selected from the group consisting of F-1) polyorganosiloxanes having at least one aliphatically unsaturated hydrocarbon group, at least one hydrolyzable group, and at least one epoxy functional group per molecule, and epoxy-functional alkoxysilanes; f-2) a combination of a polyorganosiloxane having at least one aliphatic unsaturated hydrocarbon group and at least one hydrolyzable group per molecule and an epoxy-functional alkoxysilane; and F-3) a combination of F-1) and F-2).
13. The composition of claim 2, wherein the solvent is present and is selected from the group consisting of: polyalkylsiloxanes, alcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, glycol ethers, tetrahydrofuran, mineral spirits, naphtha, or combinations thereof.
14. A method for preparing a release liner comprising a release coating on a surface of a substrate, the method comprising:
optionally treating the surface of the substrate with a treatment,
1) applying the composition of any one of the preceding claims to the surface of the substrate,
optionally 2) removing the solvent, if present;
3) curing the composition to form the release coating on the surface of the substrate.
15. The method of claim 14, wherein the composition is present in an amount sufficient to provide 0.97g/m2To 1.3g/m2The coating weight of the release coating is applied.
16. A release liner prepared by the method of claim 14.
17. The release liner of claim 16 wherein the release liner has a sustained adhesion strength of > 80% as measured by the test method in reference example 2(4) and a peel force of <3.0 g/inch as measured by the test method in reference example 2 (2).
18. Use of the release liner of claim 17 for a silicone pressure sensitive adhesive article in an electronic device application.
19. The use of claim 18, wherein the electronic device comprises a touch panel to which the pressure sensitive adhesive article is applied.
Technical Field
The silicone release coating composition can be coated on a substrate such as plastic film or paper and cured via a hydrosilylation reaction to form a release liner. Silicone release coating compositions can provide one or more benefits over release liners known in the art, such as lower release force and/or good subsequent adhesion strength and/or low mobility (for adhesives adhered to the back side of the release liner and/or substrate). Release liners can be used in applications such as electronic device applications (e.g., touch panels) for tape stripping, label stripping, and/or adhesive transfer films.
Background
Silicone release coatings are useful in applications requiring relatively non-tacky surfaces. Single-sided liners (such as backing papers for pressure sensitive adhesive labels) are typically adapted to temporarily hold the labels without affecting the adhesive properties of the labels. Double-sided liners, such as backing paper for double-sided tape and transfer tape, are used to protect the self-adhesive tape.
A disadvantage of known silicone release coatings is that the release coating composition can suffer migration if formulated to have the desired ultra-low release force.
Disclosure of Invention
A curable polyorganosiloxane release coating composition (composition) comprising:
A) a branched, aliphatically unsaturated polyorganosiloxane,
B) a crosslinking agent having at least 3 silicon-bonded hydrogen atoms per molecule,
C) a catalyst for the hydrosilylation reaction, and a catalyst,
D) a hydrosilylation reaction inhibitor, and
E) aryl-functionalized polydiorganosiloxanes with aliphatic unsaturation.
The release coating composition may be coated on the surface of a substrate and cured via a hydrosilylation reaction to produce a release liner.
Drawings
Fig. 1 shows a partial cross-section of a release liner 100. The release liner includes a release coating 101 prepared by curing the above composition on the first surface 102 of a film substrate 103. The release liner 100 also includes a carrier 104 mounted to an opposing surface 105 of the film substrate 103.
Detailed Description
A curable polyorganosiloxane release coating composition (composition) comprising:
A) a branched, aliphatically unsaturated polyorganosiloxane,
B) a crosslinking agent having at least 3 silicon-bonded hydrogen atoms per molecule,
C) a catalyst for the hydrosilylation reaction, and a catalyst,
D) a hydrosilylation reaction inhibitor, and
E) aryl-functionalized polydiorganosiloxanes with aliphatic unsaturation.
The release coating composition may also optionally comprise one or more additional starting materials selected from the group consisting of: F) an anchorage additive, G) a solvent and H) an antimisting additive.
A) Branched aliphatically unsaturated polyorganosiloxanes
In the curable polyorganosiloxane release coating compositions, the starting materials A) are branched aliphatically unsaturated polyorganosiloxanes. The branched aliphatic unsaturated polyorganosiloxane may be selected from (A-1) Q-branched polyorganosiloxanes, (A-2) silsesquioxanes, and (A-3) combinations of both (A-1) and (A-2).
The Q-branched polyorganosiloxane has the unit formula (A-I): (R)1 3SiO1/2)a(R2R1 2SiO1/2)b(R1 2SiO2/2)c(SiO4/2)dWherein each R is1Independently of one another is free of aliphatic unsaturationAnd a monovalent hydrocarbon group of the group or a monovalent halogenated hydrocarbon group free of aliphatic unsaturation, and each R2Is an aliphatically unsaturated monovalent hydrocarbon group, subscript a is 0 or more, and subscript b>C is more than or equal to 0, 15 and more than or equal to 995, and subscript d>0。
R1Examples of the monovalent hydrocarbon group of (1) are: an alkyl group of 1 to 6 carbon atoms, an aryl group of 6 to 10 carbon atoms, a haloalkyl group of 1 to 6 carbon atoms, or a haloaryl group of 6 to 10 carbon atoms. Is suitable for R1Examples of alkyl groups of (a) are, but 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, and branched, saturated hydrocarbon groups of 6 carbon atoms. Is suitable for R1Examples of aryl groups of (a) are, but not limited to, phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. Is suitable for R1Examples of haloalkyl groups of (a) are, but are not limited to, alkyl groups as described above wherein one or more hydrogen atoms are replaced by a halogen atom such as F or Cl. For example, fluoromethyl, 2-fluoropropyl, 3,3, 3-trifluoropropyl, 4,4, 4-trifluorobutyl, 4,4,4,3, 3-pentafluorobutyl, 5,5,5,4,4,3, 3-heptafluoropentyl, 6,6,6,5,5,4,4,3, 3-nonafluorohexyl, and 8,8,8,7, 7-pentafluorooctyl, 2-difluorocyclopropyl, 2, 3-difluorocyclobutyl, 3, 4-difluorocyclohexyl, and 3, 4-difluoro-5-methylcycloheptyl, chloromethyl, chloropropyl, 2-dichlorocyclopropyl, and 2, 3-dichlorocyclopentyl are examples of suitable haloalkyl groups. Is suitable for R1Examples of the halogenated aryl group of (a) are, but not limited to, the above aryl groups in which one or more hydrogen atoms are replaced with a halogen atom such as F or Cl. For example, chlorobenzyl and fluorobenzyl are suitable haloaryl groups. Alternatively, each R1Independently a monovalent hydrocarbon group free of aliphatic unsaturation. Alternatively, each R1Is an alkyl group. Alternatively, each R1Independently methyl, ethyl or propyl. R1May be the same or different. Alternatively, each R1Is a methyl group.
R2Is capable of undergoing a hydrosilylation reaction. Is suitable for R2Examples of the aliphatic unsaturated hydrocarbon group of (a) are alkenyl groups such as vinyl, allyl, butenyl and hexenyl; and alkynyl groups such as ethynyl and propynyl. Alternatively, each R2May be vinyl, allyl or hexenyl; and alternatively a vinyl or hexenyl group. R2May be the same or different. Alternatively, each R2Is a vinyl group. The subscripts in the above (a-I) unit formula may have values sufficient such that the vinyl content of the branched siloxane of (a-I) may be from 0.1% to 1%, alternatively from 0.2% to 0.5%, based on the weight of the branched siloxane (a-I).
In the unit formula of (A-I), subscript a is 0 or more. Subscript b >0. Alternatively, subscript b.gtoreq.3. Subscript c ranges from 15 to 995. Subscript d >0. Alternatively, subscript d ≧ 1. Alternatively, for subscript a: a is more than or equal to 22 and more than or equal to 0; alternatively, 20 is more than or equal to a and more than or equal to 0; alternatively, a is more than or equal to 15 and more than or equal to 0; alternatively, a is more than or equal to 10 and more than or equal to 0; and alternatively 5 ≧ a ≧ 0. Alternatively, for subscript b: 22 is more than or equal to b and more than 0; alternatively, 22 is more than or equal to b is more than or equal to 4; alternatively, 20 ≧ b > 0; alternatively, 15 ≧ b > 1; alternatively, b is more than or equal to 10 and more than or equal to 2; and alternatively 15 ≧ b ≧ 4. Alternatively, for subscript c: c is more than or equal to 800 and more than or equal to 15; and alternatively 400 ≧ c ≧ 15. Alternatively, for subscript d: d is more than or equal to 10 and more than 0; alternatively, d is more than or equal to 10 and more than or equal to 1; alternatively, 5 ≧ d > 0; and alternatively d ═ 1. Alternatively, subscript d is 1 or 2. Alternatively, when subscript d ═ 1, subscript a may be 0, and subscript b may be 4.
The Q-branched polyorganosiloxanes may contain at least two of the formulae (R)1 2SiO2/2)yWherein each subscript y is independently 2 to 100. Alternatively, the branched siloxane may comprise linkages to four of the formula (R)1 2SiO2/2)zAt least one polydiorganosiloxane chain of the formula (SiO)4/2) Wherein each subscript z independently is 1 to 100.
The Q-branched polyorganosiloxane may be one Q-branched polyorganosiloxane or a combination of more than one Q-branched polyorganosiloxane of the unit formulae (A-I) which differ in one or more properties selected from molecular weight, structure, siloxane units and sequence. Examples of Q-branched polyorganosiloxanes suitable for the starting material (A-1) are those disclosed in U.S. Pat. No. 6,806,339.
The silsesquioxane has the unit formula (A-II): (R)1 3SiO1/2)e(R2R1 2SiO1/2)f(R1 2SiO2/2)g(R1SiO3/2)hWherein R is1And R2As mentioned above, subscript e ≧ 0 and subscript f>0, subscript g is 15 to 995, and subscript h>0. Subscript e may be 0 to 10. Alternatively, for subscript e: e is more than or equal to 12 and more than or equal to 0; alternatively, e is more than or equal to 10 and more than or equal to 0; alternatively, e is more than or equal to 7 and more than or equal to 0; alternatively, e is more than or equal to 5 and more than or equal to 0; and alternatively 3 ≧ e ≧ 0.
Alternatively, subscript f ≧ 1. Alternatively, subscript f ≧ 3. Alternatively, for subscript f: 12 is more than or equal to f and more than 0; alternatively, f is more than or equal to 12 and more than or equal to 3; alternatively, 10 ≧ f > 0; alternatively, 7 is more than or equal to f is more than 1; alternatively, f is more than or equal to 5 and more than or equal to 2; and alternatively 7 ≧ f ≧ 3. Alternatively, for subscript g: 800 is more than or equal to g and more than or equal to 15; and alternatively 400. gtoreq.g.gtoreq.15. Alternatively, subscript h ≧ 1. Alternatively, subscript h is 1 to 10. Alternatively, for subscript h: h is more than or equal to 10 and more than 0; alternatively, 5 is more than or equal to h and more than 0; and alternatively h-1. Alternatively, subscript h is 1 to 10, alternatively subscript h is 1 or 2. Alternatively, when subscript h is 1, then subscript f may be 3 and subscript e may be 0. The value of subscript f may be sufficient to provide a silsesquioxane of unit formula (a-II) having an alkenyl content of from 0.1% to 1%, alternatively from 0.2% to 0.6%, based on the weight of the silsesquioxane.
The silsesquioxane can be one silsesquioxane or a combination of more than one silsesquioxane of unit formula (a-II) that differ in one or more characteristics selected from molecular weight, structure, siloxane units, and sequence. Examples of suitable silsesquioxanes for the starting material (A-2) are those disclosed in U.S. Pat. No. 4,374,967.
B) Crosslinking agent
The starting material B) is a crosslinker having an average of at least 3 silicon-bonded hydrogen atoms per molecule. The crosslinking agent may be a poly of the unit formula (B-I)Organohydrogensiloxane crosslinker: (R)1 3SiO1/2)2(R1 2SiO2/2)k(R1HSiO2/2)mWherein R is1As described above, and subscript k ≧ 0, subscript m>0, and the amount (m + k) is 8 to 400. The values of subscripts m and k may be selected such that the polyorganohydrogensiloxane crosslinker has a viscosity of from 5 to 1000mPa · s, alternatively from 10 to 350mPa · s, at 25 ℃. The amount of starting material B) added to the release coating composition may be from 0.5 to 10 parts by weight per 100 parts by weight of starting material a).
Examples of polyorganohydrogensiloxanes of component B) are:
b-1) trimethylsiloxy-terminated poly (dimethylsiloxane/methylhydrogensiloxane),
b-2) trimethylsiloxy-terminated polymethylhydrosiloxane, and
b-3) a combination of B-1) and B-2). The crosslinking agent may be a polyorganohydrogensiloxane crosslinking agent or a combination of two or more crosslinking agents that differ in one or more characteristics selected from molecular weight, structure, siloxane units, and sequence.
C) Hydrosilylation catalyst
The starting material C) is a hydrosilylation catalyst. The catalyst may be selected from: (C-1) a metal selected from the group consisting of platinum, rhodium, ruthenium, palladium, osmium and iridium; (C-2) a compound of a metal (C-1), (C-3) a complex of the compound (C-2) with an organopolysiloxane, and (C-4) a compound (C-2) microencapsulated in a matrix or core/shell structure. Suitable hydrosilylation catalysts are known in the art and are commercially available. Such conventional hydrosilylation catalysts may be (C-1) a metal selected from the group consisting of platinum, rhodium, ruthenium, palladium, osmium, and iridium. Alternatively, the hydrosilylation reaction Catalyst may be (C-2) a compound of such a metal, for example tris (triphenylphosphine) rhodium (I) chloride (Wilkinson's Catalyst), a rhodium diphosphine chelate such as [1, 2-bis (diphenylphosphino) ethane ] dichlorodirhodium or [1, 2-bis (diethylphosphine) ethane ] dichlorodirhodium, chloroplatinic acid (Speier Catalyst), chloroplatinic acid hexahydrate, platinum dichloride. Alternatively, the hydrosilylation reaction catalyst may be (C-3) a complex of the above (C-2) compound with a low molecular weight organopolysiloxane, or a platinum compound microencapsulated in a matrix or core/shell type structure. Complexes of platinum with low molecular weight organopolysiloxanes include complexes of 1, 3-divinyl-1, 1,3, 3-tetramethyldisiloxane with platinum (Karstedt's catalyst). Alternatively, the hydrosilylation reaction catalyst may include (C-4) the above compound or complex microencapsulated in a resin matrix. Exemplary hydrosilylation catalysts are described in U.S. Pat. nos. 3,159,601; 3,220,972; 3,296,291, respectively; 3,419,593; 3,516,946, respectively; 3,814, 730; 3,989,668, respectively; 4,784,879, respectively; 5,036,117, respectively; and 5,175,325 and EP 0347895B. Microencapsulated hydrosilylation catalysts and methods for making them are known in the art, as exemplified in U.S. Pat. Nos. 4,766,176 and 5,017,654.
The amount of hydrosilylation reaction catalyst used in the curable polyorganosiloxane release coating composition will depend on a number of factors including the selection of starting materials a) and B), and the respective levels of silicon-bonded hydrogen atoms and aliphatic unsaturation, however the amount of catalyst is sufficient to catalyze the hydrosilylation reaction of SiH and aliphatic unsaturation, alternatively the amount of catalyst is sufficient to provide 1ppm to 500ppm, alternatively 1ppm to 300ppm, alternatively 1ppm to 100ppm, and alternatively 5ppm to 100ppm of a platinum group metal on the same basis, based on the combined weight of all starting materials in the composition.
The starting material D) is an inhibitor. The inhibitor may be selected from: (D-1) an alkynol, (D-2) a silylated acetylenic compound, (D-3) a cycloalkenylsiloxane, (D-4) an ene-acetylenic compound, (D-5) a triazole, (D-6) a phosphine, (D-7) a thiol, (D-8) a hydrazine, (D-9) an amine, (D-10) a fumarate such as a dialkyl fumarate, a dialkenyl fumarate or a dialkoxyalkyl fumarate, (D-11) a maleate, (D-12) a nitrile, (D-13) an ether, and (D-14) a combination of two or more of (D-1) to (D-13). Suitable alkynols include dimethylhexyn and 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. Suitable cycloalkenylsiloxanes include methylvinylcyclosiloxanes, examples of which are: 1,3,5, 7-tetramethyl-1, 3,5, 7-tetravinylcyclotetrasiloxane, 1,3,5, 7-tetramethyl-1, 3,5, 7-tetrahexenylcyclotetrasiloxane, and combinations thereof. Suitable ene-yne compounds include 3-methyl-3-penten-1-yne, 3, 5-dimethyl-3-hexen-1-yne. Suitable triazoles include benzotriazole. Suitable amines include tetramethylethylenediamine. Suitable fumarates include those disclosed in U.S. patent 4,774,111. Suitable maleates include diallyl maleate.
Alternatively, the inhibitor may be a silylated acetylenic compound. Without wishing to be bound by theory, it is believed that the addition of the silylated acetylenic compound reduces yellowing of the reaction product produced by the hydrosilylation reaction of the composition as compared to the reaction product resulting from hydrosilylation of a composition that does not contain the silylated acetylenic compound or contains an organoalkynol stabilizer such as those described above.
Examples of the silylated acetylenic compound are (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) silanemethylvinylsilane, bis ((1, 1-dimethyl-2-propynyl) oxy) dimethylsilane, methyl (tris (1, 1-dimethyl-2-propynyl) silane, methyl (tris (3-methyl-1-butyn-3-oxy)) silane, (3-methyl-1-butyn-3-oxy) dimethylphenylsilane, and mixtures thereof, (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, and mixtures thereof, (cyclohexyl-1-ethynyl-1-oxy) dimethylhexenylsilane, (cyclohexyl-1-ethynyl-1-oxy) dimethylvinylsilane, (cyclohexyl-1-ethynyl-1-oxy) diphenylmethylsilane, (cyclohexyl-1-ethynyl-1-oxy) trimethylsilane, and combinations thereof. Silylated acetylenic compounds useful as inhibitors herein may be prepared by methods known in the art, for example, U.S. patent 6,677,740 discloses silylating the acetylenic alcohols described above by reacting them with chlorosilanes in the presence of an acid acceptor.
The amount of inhibitor added to the release coating composition will depend on a variety of factors including the desired pot life of the release coating composition, whether the release coating composition will be a one-part composition or a multi-part composition, the particular inhibitor used, and the selection and amount of crosslinker. However, the amount of inhibitor may be from 0.001 to 1 part by weight per 100 parts by weight of starting material a). Alternatively, the amount of inhibitor may be alternatively 0.001% to 5%, alternatively 0.001% to 1%, alternatively 0.01% to 0.5%, and alternatively 0.0025% to 0.025%, based on the weight of all starting materials in the release coating composition.
E) Aryl-functionalized polydiorganosiloxanes
The aryl-functionalized polydiorganosiloxane has the unit formula (E-1): (R)3 3SiO1/2)r(R3 2R4SiO1/2)s(R3 2R5SiO1/2)t(R3 2SiO2/2)u(R3R4SiO2/2)v(R3R5SiO2/2)w(R4 2SiO2/2)xWherein each R is3Is an independently selected alkyl group, each R4Is an independently selected aryl group, each R5Independently selected from alkenyl and alkynyl, subscript r is greater than or equal to 0, subscript s is greater than or equal to 0, subscript t is greater than or equal to 0, subscript u is greater than or equal to 0, subscript w is greater than or equal to 0, subscript x is greater than or equal to 0, amount (r + s + t) ═ 2, amount (t + w)>0 and a value sufficient to provide an aryl-functionalized polydiorganosiloxane in an amount of>0.06% to<0.24% of aliphatically unsaturated groups, amount (s + v + x)>0, and the amount (r + s + t + u + v + w + x) ≥ 3. Is suitable for R3Examples of alkyl groups of (a) are, but 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, and branched, saturated hydrocarbon groups of 6 carbon atoms. R3May be the same or different. Alternatively, each R3May be a methyl group. Is suitable for R4The aryl group of (a) may have 6 to 10 carbon atoms and is exemplified by, but not limited to, phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. R4May be the same or different. Alternatively, each R4May be phenyl. Is suitable for R5Examples of aliphatic unsaturated groups of (a) are alkenyl groups such as vinyl, allyl, butenyl and hexenyl; and alkynyl groups such as ethynyl and propynyl. Alternatively, each R5May be vinyl, allyl or hexenyl; and alternatively a vinyl or hexenyl group. R5May be the same or different. Alternatively, each R5Is a vinyl group.
The content of aliphatic unsaturated groups in the aryl-functionalized polydiorganosiloxane is > 0.06% to < 0.24%. Alternatively, the content of aliphatic unsaturation may be 0.07% to 0.21%, alternatively 0.08% to 0.19%, alternatively 0.09% to 0.16%, alternatively 0.10% to 0.14%, alternatively 0.11% to 0.13%, and alternatively 0.12%. The amount (t + w) is sufficient to provide such levels of aliphatic unsaturation to the aryl-functionalized polydiorganosiloxane.
Alternatively, the aryl-functionalized polydiorganosiloxane can have the unit formula (E-2): (R)3 3SiO1/2)2(R3 2SiO2/2)u(R3R4SiO2/2)v(R3R5SiO2/2)w(R4 2SiO2/2)xWherein u is 0-1,000, v is 0-120, 0<w.ltoreq.4, 0. ltoreq. x.ltoreq.26 and the amount (v + x) is of a value sufficient to provide a content of from 0.07% to 0.21%, alternatively 0, for the aryl-functionalized polydiorganosiloxane.08% to 0.19%, alternatively 0.09% to 0.16%, alternatively 0.10% to 0.14%, alternatively 0.11% to 0.13%, and alternatively 0.12% of aliphatic unsaturation.
Examples of aryl-functional polydiorganosiloxanes include trimethylsiloxy-terminated poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers, trimethylsiloxy-terminated poly (diphenyl/methylvinyl) siloxane copolymers, dimethylvinylsiloxy-terminated poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers, dimethylvinylsiloxy-terminated poly (diphenyl/methylvinyl) siloxane copolymers, and combinations of two or more thereof. Such aryl-functional polydiorganosiloxanes having methyl, vinyl and phenyl groups may have viscosities (cone plates) of from 500 mPa-s to 60,000 mPa-s, alternatively from 600 mPa-s to 10,000 mPa-s, and alternatively from 600 mPa-s to 8,000 mPa-s, each measured at 25 ℃ by a Brookfield Dial viscometer with cone spindle CP-52. Exemplary polysiloxanes having methyl, vinyl, and phenyl groups are known in the art and are commercially available, for example, as VPT-1323 from Gelest, Inc. Alternatively, aryl-functional polydiorganosiloxanes may be synthesized by equilibrium processes known in the art, such as those described in U.S. patent 6,956,087 and U.S. patent 5,169,920.
The amount of starting material E) aryl-functional polydiorganosiloxane in the curable polyorganosiloxane release coating composition is > 0% to 1% based on the combined weight of starting materials a), B), C), D) and E) in the composition. Alternatively, the amount of starting material E) may be 0.2% to 0.9%, and alternatively 0.4% to 0.8%, on the same basis.
Starting materials a), B), C), D), and E) are present in amounts sufficient to provide a total molar ratio of aliphatically unsaturated groups to silicon-bonded hydrogen atoms (SiH: Vi ratio) of >1.35:1 to <1.9:1, alternatively 1.4:1 to 1.8:1, alternatively 1.5:1 to 1.7:1, and alternatively 1.6: 1.
The release coating composition may also optionally include one or more additional starting materials. The additional starting materials may be selected from: F) an anchorage additive, G) a solvent and H) an antimisting additive.
F) Fixation additive
The starting substances F) are fixing additives. Examples of suitable anchorage additives are the reaction product of a vinylalkoxysilane with an epoxy-functionalized alkoxysilane; the reaction product of a vinyl acetoxy silane and an epoxy-functional alkoxysilane; and combinations (e.g., physical blends and/or reaction products) of polyorganosiloxanes having at least one aliphatically unsaturated hydrocarbon group and at least one hydrolyzable group per molecule with epoxy-functional alkoxysilanes (e.g., a combination of a hydroxyl-terminated vinyl-functional polydimethylsiloxane and glycidoxypropyltrimethoxysilane). Suitable anchorage additives and methods for their preparation are disclosed in, for example, U.S. patent application publication nos. 2003/0088042, 2004/0254274, and 2005/0038188; and EP 0556023. The exact amount of the anchorage additive depends on a variety of factors, including the type of substrate and whether or not a primer is used, however, the amount of anchorage additive in the release coating composition may be 0% to 2%, alternatively 0.01% to 2%, alternatively 0.1% to 1%, alternatively 0.2% to 0.9%, alternatively 0.3% to 0.8%, alternatively 0.4% to 0.7%, and alternatively 0.5% to 0.6%, based on the combined weight of starting materials a), B), C), D), and E).
Starting material G) solvent
Starting material G) is a solvent. Suitable solvents include polyalkylsiloxanes, alcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, glycol ethers, tetrahydrofuran, mineral spirits, naphtha, or combinations thereof. Polyalkylsiloxanes having suitable vapor pressures can be used as solvents, and these include hexamethyldisiloxane, octamethyltrisiloxane, hexamethylcyclotrisiloxane and other low molecular weight polyalkylsiloxanes, such as DOWSIL, from 0.5cSt to 1.5cStTM200 flowBody and DOWSILTMOS fluids, which are commercially available from Dow Silicones Corporation (Midland, Michigan, u.s.a.).
Alternatively, the starting material G) may comprise an organic solvent. The organic solvent may be an alcohol such as methanol, ethanol, isopropanol, butanol, or n-propanol; ketones such as acetone, methyl ethyl ketone or methyl isobutyl ketone; aromatic hydrocarbons such as benzene, toluene or xylene; aliphatic hydrocarbons such as heptane, hexane or octane; glycol ethers such as propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether or ethylene glycol n-butyl ether, tetrahydrofuran; solvent oil; naphtha; or a combination thereof.
The amount of solvent will depend on a variety of factors including the type of solvent selected and the amount and type of other starting materials selected for the curable polyorganosiloxane release coating composition. However, the amount of solvent may be from 0% to 99%, alternatively from 2% to 50%, based on the weight of all starting materials in the release coating composition. Solvents may be added during the preparation of the release coating composition, for example, to aid in mixing and delivery of one or more starting materials. For example, the catalyst may be delivered in a solvent. After the release coating composition is prepared, all or a portion of the solvent may optionally be removed.
H) Anti-fog additive
Starting material H) is an anti-mist additive which can be added to the curable polyorganosiloxane release coating composition to reduce or inhibit the formation of silicone mist during coating, especially with high speed coating equipment. The anti-mist additive may be the reaction product of an organohydrogensilicon compound, oxyalkylene compound or organoalkenylsiloxane having at least three silicon-bonded alkenyl groups per molecule and a suitable catalyst. Anti-fog additives suitable for starting material H) are disclosed in, for example, U.S. patent application 2011/0287267; us patent 8,722,153; U.S. Pat. nos. 6,586,535; and in us patent 5,625,023.
The amount of anti-fog additive will depend on a number of factors, including the amount and type of other starting materials selected for the release coating composition. However, the amount of anti-fog additive may be from 0% to 10%, alternatively from 0.1% to 3%, based on the weight of all starting materials in the release coating composition.
Other optional starting materials which may also be added to the curable polyorganosiloxane release coating compositions described herein include, for example, reactive diluents, fragrances, preservatives and fillers such as silica, quartz or chalk.
Alternatively, the curable polyorganosiloxane release coating composition may contain no filler or only a limited amount of filler, such as from 0 to 30 wt% of the release coating composition. The filler may agglomerate or otherwise adhere to the coater equipment used to apply the release coating. They can hinder the optical properties, such as transparency, of the release coating and release liner formed therefrom. The filler may be disadvantageous in adhesion to the adherend.
The curable polyorganosiloxane release coating composition may be free of conventional release modifiers that have been used in the past to control (reduce) the level of release force (adhesion between the release coating and its adherend such as a label comprising a pressure sensitive adhesive). Examples of such release modifiers include trimethylsiloxy terminated dimethyl, phenylmethylsiloxane. Without wishing to be bound by theory, it is believed that the inclusion of trimethylsiloxy terminated dimethyl, phenylmethylsiloxane in the release coating composition may reduce subsequent adhesion strength and/or increase migration of release coatings prepared therefrom.
The curable polyorganosiloxane release coating composition may be free of the fluorosilicone compound. It is believed that during curing, the fluorochemical will rapidly migrate to the interface of the coating composition and the substrate, e.g., the polyorganosiloxane release coating composition/PET film interface, due to its low surface tension, and prevent the release coating (prepared by curing the release coating composition) from adhering to the substrate by preparing a fluorine-containing barrier. By making the barrier, the fluorochemical prevents any of the components from reacting at the interface. Furthermore, fluorosilicone compounds are generally expensive.
The release coating compositions of the present invention can be prepared by mixing the starting materials together, for example, to prepare a one-part composition. However, it may be desirable to prepare the release coating composition as a multi-part composition in which the crosslinker and catalyst are stored in separate parts until the parts are combined at the time of use (e.g., immediately prior to application to a substrate).
For example, the multi-part composition may comprise:
part (A) a base part comprising A) a blend of branched aliphatic unsaturated polyorganosiloxanes, C) a hydrosilylation catalyst and E) an aryl-functional polydiorganosiloxane; and when present, H) an anti-fog additive, and
part (B) a curing agent part comprising A) a branched aliphatic unsaturated polyorganosiloxane blend and B) a crosslinking agent. Starting material D) hydrosilylation reaction inhibitor may be added to part (A), part (B), or both. When present, F) an anchorage additive and G) a solvent may be added to part (a), part (B), or both. Part (a) and part (B) may be combined in a weight ratio of 1:1 to 10:1, alternatively 1:1 to 5:1, and alternatively 1:1 to 2:1 of (a): (B). Instructions for part (a) and part (B) may be provided in the kit on how to combine the parts to prepare the release coating composition, and/or how to apply the release coating composition to a substrate.
Alternatively, when present, the anchorage additive may be incorporated into either part (a) or part (B), or it may be added to a separate (third) part.
Alternatively, the release coating composition may be prepared by a process comprising the steps of:
1) mixing starting materials comprising A) a branched aliphatic unsaturated polyorganosiloxane, B) a crosslinker, C) a hydrosilylation reaction catalyst, D) a hydrosilylation reaction inhibitor, E) an aryl-functionalized polydiorganosiloxane, and optionally one or more of F) an anchorage additive, G) a solvent, and H) an anti-fog additive, thereby forming a mixture; and
2) the mixture is applied to a substrate.
The release coating composition may be applied to the substrate, for example, by any convenient means, such as spraying, knife coating, dipping, screen printing, or by roll coating, e.g., offset web coating, kiss coating, or etch roll coating.
The release coating composition of the present invention may be applied to any substrate, such as a polymeric film substrate, for example a polyester, in particular a polyethylene terephthalate (PET), polyethylene, polypropylene or polystyrene film. Alternatively, the release coating composition may be applied to a paper substrate, including plastic coated paper (e.g., polyethylene coated paper), glassine paper, super-calendered paper, or clay coated kraft paper. Alternatively, the release coating composition may be applied to a metal foil substrate, such as aluminum foil.
The method may further comprise: 3) the substrate is treated before the mixture is coated on the substrate. Treating the substrate may be carried out by any convenient means, such as plasma treatment or corona discharge treatment. Alternatively, the substrate may be treated by applying a primer. In some cases, the anchorage of the release coating may be improved if the substrate is treated prior to coating.
The method may further comprise: 4) the solvent is removed, which can be done by any conventional means, such as heating at 50 ℃ to 100 ℃ for a time sufficient to remove all or a portion of the solvent. The method may further comprise: 5) the release coating composition is cured to form a release coating on the surface of the substrate. Curing may be carried out by any conventional means, such as heating at 100 ℃ to 200 ℃.
Under production coater conditions, curing can be achieved at an air temperature of 120 ℃ to 150 ℃ over a residence time of 1 second to 30 seconds, alternatively 1 second to 6 seconds, alternatively 1.5 seconds to 3 seconds. The heating of steps 4) and/or 5) may be carried out in an oven, such as an air circulation oven or a tunnel oven, or by passing the coated film around a heated cylinder.
The release coating may have a coating weight of 0.97g/m2To 1.3g/m2. Without wishing to be bound by theory, one benefit of the curable polyorganosiloxane release coatings described herein is at low coating weights (e.g., 1.3 g/m)2Or less) provide low peel force (as tested by the method in reference example 2(2)<3.0 g/inch) and high subsequent adhesion strength(as tested by the method in reference example 2 (4))>80%) of the total weight of the composition.
Application method
The release liner prepared as described above can be used to protect a pressure sensitive adhesive. The consumer can apply the liquid pressure sensitive adhesive composition directly onto a release liner and remove the solvent or water by heating, alternatively by UV curing, and then combine with the substrate layer and rewind into a roll. Alternatively, the consumer may laminate the release liner with a dry pressure sensitive adhesive or tacky film for tape, label, or die cut applications.
Examples
These examples are intended to illustrate some embodiments of the invention to a person skilled in the art and are not to be construed as limiting the scope of the invention as described in the claims. The following abbreviations are used: RF: peel force (peel tester), CW: coating weight (Oxford XRF), RO: rub-off (fixation performance), and SAS: subsequent adhesion strength (migration performance).
RT: room temperature at 25 ℃. Table 1 below shows the starting materials used in these examples. Unless otherwise indicated, viscosity was measured at 25 ℃.
TABLE 1 starting materials for the examples
In the above table, M represents formula (Me)3SiO1/2) Unit of (2), DPhIs represented by the formula (MePhSiO)2/2) Unit of (2), DViIs represented by the formula (MeViSiO)2/2) Unit of (2), DPh2Is represented by the formula (Ph)2SiO2/2) Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group.
Reference example 1-Preparation of anti-adhesive coating
Using the starting materials and amounts shown in the table, release coating composition samples were prepared by the following steps i.
I. Combining the following starting materials in a vessel:
i) mixture 1 or a mixture of A-2-1 and D-1-1,
ii) one of the release force modifiers E) of Table 1,
iii) an anchorage additive F-1-1, and
iv) crosslinker B-1-1 and mixed until homogeneous. If necessary, an appropriate amount of toluene solvent is added to homogenize the starting material.
Catalyst C-1-1 was added and the resulting mixture was mixed for 10 minutes to form a release coating composition.
The release coating composition was then coated on a PET substrate using a coater. The release coating composition is cured via thermal addition curing in an oven. (typically at 140 ℃ for 30 seconds). Three samples of each release coating composition (formulation F) were prepared and evaluated according to reference example 2, and the results were averaged. Unless otherwise indicated, the formulations are shown in table 2, with the amounts of each starting material being in parts by weight.
Reference example 2 evaluation of Release coating
(1) Evaluation in g/m using X-ray using an Oxford lab-X3500 instrument manufactured by Oxford Instruments PLC (Oxon, United Kingdom)2Coating weight in units (CW) to measure the coating weight of the cured release coating on the substrate. Uncoated PET was used as a control sample (blank). The test method is FINAT No. 7 (FINAT technical manual, 7 th edition, 2005).
(2) The 180 degree peel test was used to evaluate the peel force in g/in (RF-RT) to measure the peel force from the release liner. Tesa 7475 standard tape was laminated to the cured release coating and 20g/cm was applied2The load weight of (2) was placed on the laminated sample and left at RT (room temperature at 25 ℃) for 20 hours. After 20 hours, the load weight was removed and the sample was allowed to stand for 30 minutes. Then through ChemInstrThe items AR-1500 tested the peel force using FINAT test method 10 (FINAT technical Manual, 7 th edition, 2005).
(3) The 180 degree peel test was used to evaluate the peel force in g/in (RF-70 ℃ aging) to measure the peel force from the release liner. Tesa 7475 standard tape was laminated to the cured release coating and 20g/cm was applied2The load weight of (a) was placed on the laminated sample and left at 70 ℃ for 20 hours. After 20 hours, the load weight was removed and the sample was allowed to stand for 30 minutes. The peel force was then tested by chem instruments AR-1500 using FINAT test method 10 (FINAT technical manual, 7 th edition, 2005).
(4) SAS (subsequent adhesion strength, indicator of migration) in% was evaluated as follows. At 20g/cm2The test tape was laminated to the cured release coating by Nitto Denko 31B tape at a load weight and left at 70 ℃ for 20 hours. After 20 hours, the load weight was removed and the sample was allowed to stand at room temperature for 30 minutes. The 31B tape was then transferred to a PET substrate and allowed to wait an additional 1 hour. The peel force was tested by chem instruments AR-1500 using FINAT test method 11 (FINAT technical manual, 7 th edition, 2005). In this SAS test, the laminate 31B tape on PTFE substrate was tested and the PTFE sample was treated in the same manner as the cured release coating sample. Recording SAS values as RFrelease/RFPTFE×100％。
(5) Transparency was evaluated by visual inspection.
The starting materials used to prepare the different samples and the test results are shown in the table.
TABLE 2 Release coating samples, starting materials and evaluation results
Samples F1, F2, and F3; and samples F4, F5, and F6 show that release coatings prepared from compositions containing poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers as release force modifiers have higher Subsequent Adhesion Strength (SAS) than comparable release coating compositions containing trimethylsiloxy-terminated poly (dimethyl/methylphenyl) siloxane copolymers while maintaining comparable release forces tested under the same conditions. These examples also show that comparable compositions without release force modifiers produce release coatings with release forces (RF-RT) >3.0, which is undesirably high for some applications.
Samples F2, F18, and F19 show that when the SiH/Vi ratio of the release coating composition is ≦ 1.35:1, then the subsequent adhesion strength is undesirably low for some applications, and when the SiH/Vi ratio is ≧ 1.9:1, then the peel force (RF-RT) is too high (>3.0) for some applications.
The RF-RT, RF-70 ℃ and SAS evaluations described in reference example 2 were repeated except that the samples were aged for 1 month instead of 20 hours. Table 3 shows the results of these evaluations.
TABLE 3 aging evaluation
Sample (I)
F20 (working)
F21 (working)
RF-RT, 1 month
2.3
2.8
RF-70 deg.C for 1 month
4.6
5.1
SAS, 1 month
86.2
86.8
These results show that the samples have stable peel force over time and sustained adhesive strength.
TABLE 4 Release coating samples, starting materials and evaluation results
These examples show that release coatings prepared from compositions containing poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers have higher subsequent adhesion strengths than comparable release coating compositions containing trimethylsiloxy-terminated poly (dimethyl/methylphenyl) siloxane copolymers while maintaining comparable release forces tested under the same conditions. These examples also show that comparable compositions without release force modifiers produce release coatings with release forces (RF-RT) >3.0, which is undesirably high for some applications.
TABLE 5 comparative release coating compositions
Sample (I)
F11
F12
F13
F14
F15
F16
Mixture 1
80
80
80
80
80
80
B-1-1
1.52
1.57
1.57
1.57
1.66
1.57
F-1-1
0.6
0.6
0.6
0.6
0.6
0.6
C-1-1 (expressed in ppm of Pt)
130
130
130
130
130
130
E-1-2
0
20
0
0
0
E-1-3
0
0
0
0
0
20
E-1-4
0
0
20
0
0
0
E-1-5
0
0
0
20
0
0
E-1-6
20
0
0
0
0
0
E-1-7
0
0
0
0
20
0
CW
1.217
1.095
1.207
1.309
1.319
1.234
RF-RT
2.2
1.9
2.5
2.0
3.7
2.1
RF-70℃
2.6
2.1
3.4
2.3
4.8
2.9
SAS
65.7
70.6
70.1
68.7
71.9
69.6
These comparative examples show that when the amount of release force modifier is too high, the subsequent adhesion strength is < 80%, which is undesirably low for some applications. Furthermore, sample F15 shows that when a trimethylsiloxy-terminated poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymer with a vinyl content of 0.24% is used, the peel force is >3.0, which is undesirably high for some applications.
INDUSTRIAL APPLICABILITY
Release coating compositions containing aryl-functional polydiorganosiloxanes with aliphatic unsaturation are suitable for forming cured release coatings on substrates and which have desirable (high) sustained adhesion strength and (low) release force, making them suitable for use in electronic device applications, such as release liners for silicone pressure sensitive adhesives in electronic device applications such as touch panels. Without wishing to be bound by theory, it is believed that the aliphatic unsaturation reacts to form a partially cured network on the substrate that can provide a lower peel force to the tacky adhesive while maintaining a higher subsequent adhesion strength.
Embodiments of the invention
1. A curable polyorganosiloxane release coating composition (composition) comprising:
A) a branched aliphatic unsaturated polyorganosiloxane;
B) a cross-linking agent having at least 3 silicon-bonded hydrogen atoms per molecule;
C) a hydrosilylation reaction catalyst in an amount sufficient to provide from 1ppm to 500ppm by weight of a platinum group metal based on the combined weight of starting materials a), B), C), D), and E);
D) a hydrosilylation reaction inhibitor in an amount of 0.001% to 5% based on the combined weight of starting materials a), B), C), D), and E); and
E) an aryl-functionalized polydiorganosiloxane having an aliphatically unsaturated group content of 0.07% to 0.23%, wherein starting material E) is present in an amount of 0.4% to 0.8% based on the combined weight of starting materials A), B), C), D), and E); and is
Wherein all starting materials are present in an amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms to aliphatic unsaturation (overall SiH: Vi ratio) of from 1.4:1 to 1.8:1 in the release coating composition.
2. The composition of embodiment 1 further comprising one or more additional starting materials selected from the group consisting of F) anchorage additives, G) solvents, and H) anti-fog additives.
3. The composition of embodiment 1 or embodiment 2, wherein the branched aliphatic unsaturated polyorganosiloxane is selected from the group consisting of:
unit formula (A-1) (R)1 3SiO1/2)a(R2R1 2SiO1/2)b(R1 2SiO2/2)c(SiO4/2)dWherein each R is1Independently a monovalent hydrocarbon group free of aliphatic unsaturation, and each R2Is an aliphatic unsaturated hydrocarbon group, wherein subscript a is 0 or more and subscript b>0, subscript c is 15 to 995, and subscript d>0；
Unit formula (A-2) (R)1 3SiO1/2)e(R2R1 2SiO1/2)f(R1 2SiO2/2)g(R1SiO3/2)hWherein the subscript e ≧0, subscript f>0, subscript g is 15 to 995, and subscript h>0; and a combination of both (A-1) and (A-2).
4. The composition of embodiment 3, wherein 22. gtoreq.a.gtoreq.0, 22. gtoreq.b >0, 995. gtoreq.c.gtoreq.15, 10. gtoreq.d >0, 12. gtoreq.0, 12. gtoreq.f >0, 995. gtoreq.g.gtoreq.15, and 10. gtoreq.h >0.
5. The composition of embodiment 3 or embodiment 4, wherein each R1Is an alkyl group of 1 to 6 carbon atoms, and each R2Is an alkenyl group of 2 to 6 carbon atoms.
6. The composition of embodiment 5 wherein each R1Is methyl, and each R2Is a vinyl group.
7. The composition of any of embodiments 1-6, wherein the crosslinker has the unit formula (B-1): (R)1 3SiO1/2)2(R1 2SiO2/2)k(R1HSiO2/2)mWherein each R is1Independently selected from the group consisting of monovalent hydrocarbon groups free of aliphatic unsaturation and monovalent halogenated hydrocarbon groups free of aliphatic unsaturation, subscript k ≧ 0, subscript m>0, and the amount (m + k) is 8 to 400.
8. The composition of embodiment 7 wherein in unit formula (B-1), each R1Is an alkyl group of 1 to 6 carbon atoms.
9. The composition of embodiment 8 wherein each R1Is methyl.
10. The composition according to any one of embodiments 1 to 9, wherein the platinum group metal catalyst is selected from the group consisting of: (C-1) a metal selected from the group consisting of platinum, rhodium, ruthenium, palladium, osmium and iridium; (C-2) a compound of said metal (C-1), (C-3) a complex of said compound (C-2) with an organopolysiloxane, and (C-4) said compound (C-2) microencapsulated in a matrix or core/shell type structure.
11. The composition according to any one of embodiments 1 to 10, wherein the hydrosilylation reaction inhibitor is selected from the group consisting of a combination of two or more of (D-1) an acetylenic alcohol, (D-2) a silylated acetylenic compound, (D-3) a cycloalkenylsiloxane, (D-4) an ene-yne compound, (D-5) a triazole, (D-6) a phosphine, (D-7) a thiol, (D-8) a hydrazine, (D-9) an amine, (D-10) a fumarate, (D-11) a maleate, (D-12) a nitrile, (D-13) an ether, and (D-14) (D-1) to (D-13).
12. The composition of any of embodiments 1 to 11 wherein the aryl-functionalized polydiorganosiloxane has the unit formula: (R)3 3SiO1/2)r(R3 2R4SiO1/2)s(R3 2R5SiO1/2)t(R3 2SiO2/2)u(R3R4SiO2/2)v(R3R5SiO2/2)w(R4 2SiO2/2)xWherein each R is3Is an independently selected alkyl group, each R4Is an independently selected aryl group, each R5Independently selected from alkenyl and alkynyl, subscript r is greater than or equal to 0, subscript s is greater than or equal to 0, subscript t is greater than or equal to 0, subscript u is greater than or equal to 0, subscript w is greater than or equal to 0, subscript x is greater than or equal to 0, and the amount (r + s + t) is 2, the amount (t + w) being sufficient to provide the aryl-functionalized polydiorganosiloxane in an amount of>0.06% to<0.24% of aliphatically unsaturated groups, amount (s + v + x)>0, and the amount (r + s + t + u + v + w + x) ≥ 3.
13. The composition of embodiment 12 wherein the aryl-functionalized polydiorganosiloxane has the unit formula: (R)3 3SiO1/2)2(R3 2SiO2/2)u(R3R4SiO2/2)v(R3R5SiO2/2)w(R4 2SiO2/2)xWherein u is 0-1,000, v is 0-120, 0<w ≦ 4, 0 ≦ x ≦ 26, and the value of the amount (v + x) is sufficient to provide the aryl-functionalized polydiorganosiloxane with an aliphatic unsaturation in an amount of 0.07% to 0.21%, alternatively 0.08% to 0.19%, alternatively 0.09% to 0.16%, alternatively 0.10% to 0.14%, alternatively 0.11% to 0.13%, and alternatively 0.12%.
14. The composition of embodiment 13 wherein the aryl-functional polydiorganosiloxane has a viscosity of 500 to 60,000 mPa-s and is selected from trimethylsiloxy-terminated poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers, trimethylsiloxy-terminated poly (diphenyl/methylvinyl) siloxane copolymers, dimethylvinylsiloxy-terminated poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers, dimethylvinylsiloxy-terminated poly (diphenyl/methylvinyl) siloxane copolymers, and mixtures thereof, And combinations of two or more thereof.
15. The composition of embodiment 14 wherein the aryl-functional polydiorganosiloxane has a viscosity of 600 to 60,000 mPa-s and is selected from trimethylsiloxy-terminated poly (dimethyl/methylphenyl/methylvinyl) siloxane copolymers, trimethylsiloxy-terminated poly (diphenyl/methylvinyl) siloxane copolymers, and combinations of two or more thereof.
16. The composition of embodiment 2 wherein F) the anchor additive is present and the anchor additive is selected from the group consisting of F-1) polyorganosiloxanes having at least one aliphatically unsaturated hydrocarbon group, at least one hydrolyzable group, and at least one epoxy functional group per molecule, and epoxy-functional alkoxysilanes; f-2) a combination of a polyorganosiloxane having at least one aliphatic unsaturated hydrocarbon group and at least one hydrolyzable group per molecule and an epoxy-functional alkoxysilane; and F-3) a combination of F-1) and F-2).
17. The composition of embodiment 2, wherein the solvent is present and is selected from the group consisting of: polyalkylsiloxanes, alcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, glycol ethers, tetrahydrofuran, mineral spirits, naphtha, or combinations thereof.
18. A method for preparing a release liner comprising a release coating on a surface of a substrate, the method comprising:
optionally treating the surface of the substrate with a treatment,
1) applying the composition according to any one of embodiments 1 to 17 to the surface of the substrate,
optionally 2) removing the solvent, if present;
3) curing the composition to form the release coating on the surface of the substrate.
19. The method of embodiment 186, wherein the composition is in an amount sufficient to provide 0.97g/m2To 1.3g/m2The coating weight of the release coating is applied.
20. A release liner prepared by the method of embodiment 18 or embodiment 19.
21. The release liner according to embodiment 20, wherein the release liner has a sustained adhesion strength of > 80% as measured by the test method in reference example 2(4) and a peel force of <3.0 g/inch as measured by the test method in reference example 2 (2).
22. Use of the release liner according to embodiment 20 or embodiment 21 for a silicone pressure sensitive adhesive article in an electronic device application.
23. The use of embodiment 22, wherein the electronic device comprises a touch panel to which the pressure sensitive adhesive article is applied.
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