JP2024515526A - Pressure-sensitive adhesive composition and method for preparing same and use in flexible organic light-emitting diodes - Patents.com - Google Patents

Abstract

The pressure-sensitive adhesive composition can be cured by hydrosilylation to form a pressure-sensitive adhesive. The pressure-sensitive adhesive composition can be coated on a substrate and cured to form a protective film. The protective film is useful, for example, in the fabrication process of flexible OLED devices to protect the passivation layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/172,737, filed April 9, 2021. U.S. Provisional Patent Application No. 63/172,737 is incorporated herein by reference.

The present invention relates to a pressure-sensitive adhesive composition useful in a process for fabricating flexible organic light-emitting diode (OLED) displays. The pressure-sensitive adhesive composition is cured to form a pressure-sensitive adhesive that has low initial adhesion, high adhesion stability over time, and low migration.

In a typical process for making flexible OLED displays, the OLED is formed on a relatively rigid substrate (e.g., glass or glass coated with a polyimide varnish) and a passivation layer is formed on the surface of the OLED opposite the substrate. During further processing, the rigid substrate is removed. Weak or fragile layers need to be protected from damage (e.g., scratches or other impacts) during further processing.

To protect layers during the fabrication process, a protective film with low adhesion is desired to prevent delamination of layers (e.g., passivation layers) on the surface of the OLED module when the protective film is peeled off after use. If adhesion control fails and adhesion increases over time (i.e., during the fabrication process), layers may delaminate or be damaged when the protective film is removed. Therefore, the industry needs to provide protective films with low adhesion and high adhesion stability (where adhesion does not increase during the time required for the fabrication process to a degree that would cause delamination or damage).

It is also important to keep the surface of the layer clean so that additional films or layers can be laminated after the protective film is removed. Thus, there is a need in the industry to provide protective films that have low migration properties (so that no or minimal adhesive from the protective film remains on the surface of the layer of the flexible OLED device after the protective film is removed).

The pressure sensitive adhesive composition comprises
a poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer having silicon-bonded alkyl groups having 1 to 10 carbon atoms and silicon-bonded alkenyl groups having 2 to 6 carbon atoms, the alkenyl groups being present in an amount of 0.14% to <0.3%, based on the weight of the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer;
a polyalkylhydrogensiloxane having the unit formula (R ¹ ₂ HSiO _1/2 ) ₂ (R ¹ ₂ SiO _2/2 ) _x (R ¹ HSiO _2/2 ) _y , where each R ¹ is an independently selected alkyl group of 1 to 10 carbon atoms, subscript x≧0, subscript y≧0, and the amount (x+y) is sufficient for the viscosity of the polyalkylhydrogensiloxane to be <20 mPa·s;
A platinum group metal catalyst;
Acetylenic alcohol,
and an organic solvent.

Also disclosed are methods for preparing the pressure-sensitive adhesive composition, methods for forming a pressure-sensitive adhesive tape using the pressure-sensitive adhesive composition, and methods for fabricating a flexible organic light-emitting diode device using the pressure-sensitive adhesive tape.

The pressure sensitive adhesive composition comprises
A) 85 to 100 parts by weight of a poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer having silicon-bonded alkyl groups having 1 to 10 carbon atoms and silicon-bonded alkenyl groups having 2 to 6 carbon atoms, the alkenyl groups being present in an amount of 0.14% to <0.3% based on the weight of the copolymer;
C) 0.1 to 5 parts by weight of a polyalkylhydrogensiloxane having the unit formula (R ¹ ₂ HSiO _1/2 ) ₂ (R ¹ ₂ SiO _2/2 ) _x (R ¹ HSiO _2/2 ) _y , where each R ¹ is an independently selected alkyl group of 1 to 10 carbon atoms, subscript x > 0, subscript y > 0, and the amount (x + y) is sufficient for the viscosity of the polyalkylhydrogensiloxane to be < 20 mPa·s (alternatively 8 mPa·s to 16 mPa·s);
F) a platinum group metal catalyst in an amount sufficient to provide a 10-5000 ppm concentration of Pt group metal in the composition;
E) 0.01 to 1 part by weight of acetylene alcohol;
G) 10% to 90% by weight of an organic solvent, based on the combined weight of all starting materials in the composition, provided that all starting materials in the combined composition have a molar ratio of silicon-bonded hydrogen atoms to silicon-bonded alkenyl groups (SiH:Alkenyl ratio) of 0.5:1 to 2:1.

Starting Material A) Poly(dialkylsiloxane/alkylalkenylsiloxane) Copolymer Starting material A) in the pressure sensitive adhesive composition is a poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer having silicon-bonded alkyl groups having 1 to 10 carbon atoms and silicon-bonded alkenyl groups having 2 to 6 carbon atoms, the alkenyl groups being present in an amount of 0.14% to <0.3%, based on the weight of the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer. Alternatively, starting material A) may contain at least 0.15%, alternatively >0.20%, alternatively at least 0.21%, alternatively at least 0.22% alkenyl groups, while at the same time starting material A) may contain, on the same basis, up to 0.29%, alternatively up to 0.28%, alternatively up to 0.27%, alternatively up to 0.26%, alternatively up to 0.25%, alternatively up to 0.24%, alternatively up to 0.23%, alternatively up to 0.22%, and alternatively up to 0.21% alkenyl groups. Alternatively, the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer may contain 0.14% to <0.3%, alternatively >0.20% to 0.26% alkenyl groups, alternatively 0.202% alkenyl groups. Without being bound by theory, if the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer contains >0.3% alkenyl groups, the pressure-sensitive adhesive prepared from the composition may cause burrs, which may cause damage to the passivation layer when the pressure-sensitive adhesive film is removed during the fabrication of electronic devices such as flexible organic light-emitting diode devices. Also, if the alkenyl content of the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer is too low (e.g., <0.14%), migration may increase, subsequent adhesion strength test results may be too low, and/or adhesion may increase with age (poor adhesion stability may result). Starting material A) may not contain silicon-bonded aromatic hydrocarbyl groups. In this context, "free" means that the starting material A) does not contain aromatic hydrocarbyl groups (such as phenyl, tolyl, xylyl, or benzyl) or amounts of aromatic hydrocarbyl groups that are not detectable by gas chromatography mass spectrometry (GCMS) analysis.

The starting material A) may comprise a poly(dialkylsiloxane/alkylalkenylsiloxane) of average unit formula (I): (R ¹ ₂ R ² SiO _1/2 ) _d (R ¹ ₃ SiO _1/2 ) _e (R ¹ R ² SiO _2/2 ) _f (R ¹ ₂ SiO _2/2 ) _g , where subscript d≧0, subscript e≧0, subscript f>0, subscript g≧0, the amount (d+e)=2, and the amount (d+e+f+g) is from 3 to 10,000, alternatively from 2,000 to 9,500, alternatively from 4,500 to 5,000. Alternatively, the subscripts d, e, f, and g have values such that 2≧d≧0, 2≧e≧0, 70≧f≧0, 10,000≧g≧0. Alternatively, the subscript f may have a value such that 50≧f≧0, alternatively 40≧f≧10, alternatively 37≧f≧20. Alternatively, the subscript g may have a value such that 9,500≧g≧0, alternatively 5,500≧g≧4,000, alternatively 5,000≧g≧4,500, alternatively 4,950≧g≧4,450. The subscripts d, e, f, and g have values selected such that the poly(dialkylsiloxane/alkylalkenylsiloxane) has the alkenyl content set forth above. Alternatively, the subscripts d, e, f, and g may have values such that the number average molecular weight (Mn) of the starting material A) is at least 200,000 g/mol, alternatively at least 250,000 g/mol, alternatively at least 300,000 g/mol, alternatively at least 330,000 g/mol, while at the same time Mn may be at most 500,000 g/mol, alternatively at most 450,000 g/mol, alternatively at most 400,000 g/mol, alternatively at most 370,000 g/mol, as measured by gel permeation chromatography according to the test method of column 31, Reference Example 1 of U.S. Pat. No. 9,593,209.

In unit formula (I), each R ¹ is independently an alkyl group of 1 to 10 carbon atoms, and each R ² is independently an alkenyl group of 2 to 6 carbon atoms. Suitable alkyl groups include branched or unbranched saturated monovalent hydrocarbon groups. Alkyl is exemplified by, 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, heptyl, octyl, nonyl and decyl, and branched saturated monovalent hydrocarbon groups of 6 to 10 carbon atoms. Alternatively, each R ¹ may be selected from methyl, ethyl, and isopropyl. Alternatively, each R ¹ may be methyl. Suitable alkenyl groups include branched or unbranched monovalent hydrocarbon groups having a terminal double bond. Alkenyl is exemplified by, but is not limited to, vinyl, allyl, butenyl (e.g., isobutenyl, n-butenyl, tert-butenyl, and/or sec-butenyl), and hexenyl, which include branched and straight chain groups of 6 carbon atoms. Alternatively, each ^R2 can be an alkenyl. Alternatively, each ^R2 can be vinyl, allyl, or hexenyl. Alternatively, each ^R2 can be vinyl or hexenyl.

The alkenyl content of the starting material A) can be calculated by calculating the total molecular weight of the poly(dialkylsiloxane/alkylalkenylsiloxane), calculating the molecular weight of each unit containing an alkenyl group, and dividing the combined molecular weights of each unit containing an alkenyl group by the total molecular weight. For example, starting material A, ₍ ^{R12R2SiO1 /2} _{) d} ( _R13SiO1 ^/ ₂ ) _e ⁽ R1R2SiO2 ^/ ₂ ) _f ( ^R12SiO2 _{/ 2} ) _g , where ^R1 is methyl, ^R2 is vinyl, subscript d=2, subscript e=0, subscript f=25, and subscript g=4829, is a dimethylvinylsiloxy-terminated poly(dimethylsiloxane/ _{methylvinylsiloxane} ) copolymer ( _{MVi2DVi25D4829} ) and the number average molecular weight ( ^Mn ) and ^alkenyl ( _vinyl ) content are calculated as follows:
Number average molecular weight of the copolymer, 360,429.89 gf/mol M ^Vi Mw = 93.20 g/mol, D Mw = 74.15 g/mol and D ^Vi Mw = 86.17 g/mol → Mn M ^Vi D ₄₈₂₉ D ^Vi ₂₅ M ^Vi = 2 * 93.2 + 4829 * 74.15 + 25 * 86.17 = 360,429.89 g/mol Vinyl content = 0.202%
M ^Vi Mw = 93.20 g/mol, D Mw = 74.15 g/mol, D ^vi Mw = 86.17 g/mol, and vinyl Mw = 27;
→ M ^Vi D ₄₈₂₉ D ^Vi ₂₅ M ^Vi 's Mn = (27 * 27) / (2 * 93.2 + 4829 * 74.15 + 25 * 86.17) x 100% = 0.2022%

The starting material A) is
i) dimethylvinylsiloxy-terminated poly(dimethylsiloxane/methylvinylsiloxane);
ii) dimethylvinylsiloxy-terminated polymethylvinylsiloxane;
iii) bis-trimethylsiloxy-terminated poly(dimethylsiloxane/methylvinylsiloxane);
iv) trimethylsiloxy-terminated polymethylvinylsiloxane;
v) dimethylvinylsiloxy-terminated poly(dimethylsiloxane/methylvinylsiloxane);
vi) dimethylhexenylsiloxy-terminated poly(dimethylsiloxane/methylhexenylsiloxane);
vii) dimethylhexenylsiloxy-terminated polymethylhexenylsiloxane;
viii) trimethylsiloxy-terminated poly(dimethylsiloxane/methylhexenylsiloxane);
ix) trimethylsiloxy-terminated polymethylhexenyl siloxane;
x) dimethylhexenylsiloxy-terminated poly(dimethylsiloxane/methylhexenylsiloxane);
xi) is exemplified by a combination of two or more of i), ii), iii), iv), v), vi), vii), viii), ix), and x).

Starting material A) can be one poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer or a combination of two or more poly(dialkylsiloxane/alkylalkenylsiloxane) copolymers that differ in at least one property, such as the selection of alkyl groups, the selection of alkenyl groups, the molecular weight, and the number of dialkylsiloxane units and alkylalkenylsiloxane units. Methods for the preparation of poly(dialkylsiloxane/alkylalkenylsiloxane) suitable for use as starting material A), such as hydrolysis and condensation of the corresponding organohalosilanes or equilibration of cyclic polydiorganosiloxanes, are well known in the art.

Starting Material B) Polyalkylsiloxane Resin The pressure sensitive adhesive composition may optionally further comprise starting material B) a polyalkylsiloxane resin. The polyalkylsiloxane resin is an MQ resin consisting essentially of R ³ ₃ SiO _1/2 (M) and SiO _4/2 (Q) units, where each R ³ is independently selected from the group consisting of alkyl groups of 1 to 10 carbon atoms as described above for R ¹ , and alkenyl groups of 2 to 6 carbon atoms as described above for R ^2. Starting material B) may be free of silicon-bonded aromatic hydrocarbyl groups.

As prepared, the polyorganosilicate resins contain the M and Q units described above and may further contain units having silanol (silicon-bonded hydroxyl) groups and may also include neopentamers of the formula Si(OSiR ³ _{O 3} ) ₄ , where R ³ is as defined above. As described in Reference Example 2 of column 32 of U.S. Pat. No. 9,593,209, using Si ²⁹ nuclear magnetic resonance (NMR) spectroscopy, the moles of M and Q units are expressed as M(resin)+(M(neopentamer))/(Q(resin)+Q(neopentamer)), which represents the molar ratio of the total number of triorganosiloxy groups (M units) in the resin and neopentamer portions of the polyorganosilicate resin to the total number of silicate groups (Q units) in the resin and neopentamer portions (M:Q ratio). The M:Q ratio can be from 0.5:1 to 1.5:1, alternatively from 0.6:1 to 1.2:1.

The Mn of the polyorganosilicate resin depends on a variety of factors, including the type of hydrocarbon group represented by ^R3 present. The Mn of the polyorganosilicate resin refers to the number average molecular weight measured using gel permeation chromatography (GPC) according to the procedure in Reference Example 1, column 31 of U.S. Pat. No. 9,593,209, where the peak representing the neopentamer is excluded from the measurement. The Mn of the polyorganosilicate resin can be 2,000 g/mol or more, alternatively >2,000 g/mol to 10,000 g/mol, alternatively 3,000 g/mol to 8,000 g/mol. Alternatively, the Mn of the polyorganosilicate resin can be 4,000 g/mol to 7,000 g/mol.

No. 8,580,073, column 3, line 5 to column 4, line 31, are incorporated herein by reference to disclose silicone resins that are suitable polyorganosilicate resins for use herein. The polyorganosilicate resins can be prepared by any suitable method, such as cohydrolysis of the corresponding silanes or a silica hydrosol capping method. The polyorganosilicate resins can be prepared by a silica hydrogel capping process, such as those disclosed in U.S. Pat. No. 2,676,182 to Daudt et al., U.S. Pat. No. 4,611,042 to Rivers-Farrell et al., and U.S. Pat. No. 4,774,310 to Butler et al. The Daudt et al. method involves reacting a silica hydrosol 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 copolymers typically contain 2 to 5 weight percent silicon-bonded hydroxyl (silanol) groups.

The intermediates used to prepare the polyorganosilicate resins can be triorganosilanes and silanes or alkali metal silicates containing four hydrolyzable substituents. The triorganosilanes can have the formula R ³ ₃ SiX ¹ , where R ³ is as above and X ¹ represents a hydrolyzable substituent such as halogen, alkoxy, acyloxy, hydroxyl, oximo, or ketoximo, alternatively halogen, alkoxy, or hydroxyl. The silanes with four hydrolyzable substituents can have the formula SiX ² ₄ , where each X ² is halogen, alkoxy, or hydroxyl. Suitable alkali metal silicates include sodium silicates.

The polyorganosilicate resins prepared as described above typically contain silicon-bonded hydroxyl groups, for example, with units of the formula HOSi _3/2 and/or HOR ³ ₂ SiO _1/2 . The polyorganosilicate resins may contain up to 2% silicon-bonded hydroxyl groups. The concentration of silicon-bonded hydroxyl groups present in the polyorganosilicate resins can be determined using Fourier Transform-Infra Red (FTIR) spectroscopy in accordance with ASTM Standard E-168-16. In certain applications, it may be desirable for the amount of silicon-bonded hydroxyl groups to be less than 0.7%, alternatively less than 0.3%, alternatively less than 1%, alternatively between 0.3% and 0.8%. The silicon-bonded hydroxyl groups formed during the preparation of the polyorganosilicate resin can be converted to trihydrocarbylsiloxy groups, or other hydrolyzable groups, by reacting the polyorganosilicate resin with a silane, disiloxane, or disilazane containing the appropriate terminal group. The silane containing the hydrolyzable group may be added in molar excess over the amount required to react with the silicon-bonded hydroxyl groups in the polyorganosilicate resin.

Alternatively, the polyorganosilicate resin may further comprise up to 2%, alternatively up to 0.7%, alternatively up to 0.3%, alternatively from 0.3% to 0.8% of units represented by the formula XSiO3 _/2 and/or ^NXR32SiO1 _{/ 2} , where ^R3 is as defined above and X represents a hydrolyzable substituent as defined above for ^X1 .

Alternatively, the polyorganosilicate resin may have terminal aliphatic unsaturation. Polyorganosilicate resins having terminal aliphatic unsaturation may be prepared by reacting the product of Daudt et al. with an unsaturated organic group-containing end-capping agent and an end-capping agent free of aliphatic unsaturation in an amount sufficient to provide 3-30 mole percent unsaturated organic groups in the final product. Examples of end-capping agents include, but are not limited to, silazanes, siloxanes, and silanes. Suitable end-capping agents are known in the art and are exemplified in U.S. Pat. Nos. 4,584,355, 4,591,622, and 4,585,836. A single end-capping agent or a mixture of such agents may be used to prepare such resins.

Alternatively, the polyalkylsiloxane resin may comprise the unit formula (II): ( ^R12R2SiO1 _/ ² ) _a ( ^R13SiO1 _{/ 2} ) _b (SiO4 _/2 ) _c , where ^R1 and ^R2 _are as defined above and subscripts a, b, and c represent mole fractions having values such that subscript a > 0, subscript b > 0, subscript c > 0, the amount (a+b) > 0, and subscripts a, b, and c have values such that 0.9 < (a+b)/c < 1.3.

The amount of starting material B) in the pressure-sensitive adhesive composition depends on a variety of factors, including the desired form of the reaction product of the composition, the amount and hydrosilylation reactivity of alkenyl groups in starting material A), the type and amount of catalyst, and the silicon-bonded hydrogen atom content of starting material C). Alternatively, the amount of starting material B) can range from 0 to 15 parts by weight, alternatively >0 to 15 parts by weight, per 100 parts by weight of starting material A) on the same basis.

Starting Material C) Polyalkylhydrogensiloxane The pressure sensitive adhesive composition further comprises starting material C) a polyalkylhydrogensiloxane. The polyalkylhydrogensiloxane has the formula (III):
(R ¹ ₂ HSiO _1/2 ) ₂ (R ¹ ₂ SiO _2/2 ) _x (R ¹ HSiO _2/2 ) _y , where R ¹ is as defined above.

In formula (III), subscript x > 0, subscript y > 0, and the amount (x + y) is sufficient to provide the polyalkylhydrogensiloxane with a viscosity of < 20 mPa·s, alternatively 8 mPa·s to 16 mPa·s, as measured by a capillary viscometer at 25°C. Subscript x may be sufficient to provide starting material C), the polyalkylhydrogensiloxane, with a SiH content of > 0 to < 1%, alternatively > 0 to 0.75%, based on the weight of starting material C).

The polyalkylhydrogensiloxanes of starting material C) are exemplified by the following:
a) dimethylhydrogensiloxy-terminated polydimethylsiloxane;
b) dimethylhydrogensiloxy-terminated poly(dimethylsiloxane/methylhydrogensiloxane);
c) dimethylhydrogensiloxy-terminated polymethylhydrogensiloxane; and d) a combination of two or more of a), b) and c).

Methods for preparing polyalkylhydrogensiloxanes suitable for use as starting material C), such as hydrolysis and condensation of organohalosilanes, are well known in the art.

The exact amount of starting material C) in the composition will depend on a variety of factors, including the reactivity of starting material A), whether starting material B) is present, and, if present, the type and amount of any additional starting materials (e.g., starting material D). However, the amount of starting material C) in the pressure-sensitive adhesive composition may be from 0.1% to 5%, alternatively from 0.5% to 3%, alternatively from 0.5% to 2%, based on the total weight of all starting materials in the composition.

The alkenyl content of starting material A) and any other starting materials in the composition containing silicon-bonded alkenyl groups (e.g., if alkenyl-functional, starting material B) and starting material C)) and the SiH content of starting material B) and any other SiH-containing materials in the pressure-sensitive adhesive composition (e.g., if SiH-functional, starting material D) adhesion promoter) are sufficient to provide a pressure-sensitive adhesive composition having a molar ratio of silicon-bonded hydrogen atoms to silicon-bonded alkenyl groups (SiH/alkenyl) ratio of at least 0.5:1, alternatively up to 2:1, alternatively 0.5:1 to 2:1, alternatively 1:1 to 1.5:1, and alternatively >1 to 1.2.

Starting material D) Anchoring additive Starting material D) is an anchoring additive that can be optionally included in the pressure-sensitive adhesive composition. Without being bound by theory, it is believed that the anchoring additive promotes the bonding of the pressure-sensitive adhesive prepared by curing the pressure-sensitive adhesive composition described herein to a substrate. However, the presence of the anchoring additive does not adversely affect the desired peel force, thereby allowing the pressure-sensitive adhesive to be removed from an electronic device without damaging the device or leaving significant residue.

Suitable fixation additives 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, as well as mixtures or reaction mixtures of such silane coupling agents. Alternatively, the fixation additive can be tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, allyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or 3-methacryloxypropyltrimethoxysilane.

Alternatively, examples of the fixing additives include reaction products of alkenyl-functional alkoxysilanes (e.g., vinyl alkoxysilanes) with epoxy-functional alkoxysilanes, reaction products of alkenyl-functional acetoxysilanes (e.g., vinyl acetoxysilanes) with epoxy-functional alkoxysilanes, 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 hydroxy-terminated vinyl-functional polydimethylsiloxane and glycidoxypropyltrimethoxysilane). Suitable fixing additives and methods for their preparation are disclosed, for example, in U.S. Pat. No. 9,562,149, U.S. Patent Application Publication Nos. 2003/0088042, 2004/0254274, 2005/0038188, and 2012/0328863, paragraph [0091], and U.S. Patent Application Publication No. 2017/0233612, paragraph [0041], and European Patent No. 0556023.

Fixation additives are commercially available. For example, SYL-OFF™ 297, SYL-OFF™ 397, and SYL-OFF™ 9176 are available from Dow Silicones Corporation (Midland, Michigan, USA). Other exemplary fixation additives include D-1) vinyltriacetoxysilane, D-2) glycidoxypropyltrimethoxysilane, D-3) 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, D-4) combinations of two or more of D-1), D-2), and D-3), and D-5) combinations of any of D-1), D-2), D-3), and/or D-4) with polydimethylsiloxanes terminated with hydroxyl groups, methoxy groups, or both hydroxyl and methoxy groups. The combination of D-4) and D-5) can be a physical blend and/or a reaction product.

The amount of the adhesion promoter will vary depending on a variety of factors, including the type of substrate to which the composition is applied and whether a primer or other surface treatment is used prior to application of the composition. However, the amount of adhesion promoter may be 0-5%, alternatively 1%-5%, alternatively 1%-3%, alternatively 0%-1%, based on the combined weight of all starting materials in the composition. The adhesion promoter may be free of silicon-bonded aromatic hydrocarbyl groups.

Starting Material E) Inhibitor The pressure sensitive adhesive composition further comprises starting material E) an acetylenic alcohol. The acetylenic alcohol may be added as an inhibitor or stabilizer of the pressure sensitive adhesive composition. Suitable acetylenic alcohols are exemplified by methylbutynol, ethynylcyclohexanol (ETCH), dimethylhexynol, 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. Alternatively, starting material E) may be selected from the group consisting of (E-1) 1-ethynyl-1-cyclohexanol, (E-2) methylbutynol, (E-3) diallyl maleate, and (E-4) a combination of two or more of (E-1), (E-2), and (E-3). Alternatively, starting material E) is exemplified by ETCH.

The amount of acetylenic alcohol added to the composition will depend on a variety of factors, including the desired pot life of the pressure-sensitive adhesive composition, whether the composition is a one-part or multi-part composition, the particular acetylenic alcohol used, and the selection and amount of starting material C). However, when present, the amount of starting material E) may range from 0.01 to 0.5 parts by weight.

Starting Material F) Hydrosilylation Reaction Catalyst The pressure-sensitive adhesive composition further comprises starting material F) a hydrosilylation reaction catalyst. Suitable hydrosilylation reaction catalysts are known in the art and commercially available. The hydrosilylation catalyst may be a platinum group metal selected from platinum, rhodium, ruthenium, palladium, osmium, and iridium. Alternatively, the hydrosilylation catalyst may be a compound of such a metal (e.g., chloroplatinic acid, chloroplatinic acid hexahydrate, platinum dichloride), and complexes of the above compounds with low molecular weight organopolysiloxanes, or platinum compounds microencapsulated in a matrix or core/shell type structure. Complexes of platinum with low molecular weight organopolysiloxanes include 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane complexes with platinum. These complexes may be microencapsulated in a resin matrix. Exemplary hydrosilylation catalysts are described in U.S. Patent Nos. 3,159,601, 3,220,972, 3,296,291, 3,419,593, 3,516,946, 3,814,730, 3,989,668, 4,784,879, 5,036,117, and 5,175,325, and in European Patent No. 0347895(B). Microencapsulated hydrosilylation catalysts and methods for their preparation are known in the art, as exemplified in U.S. Patent Nos. 4,766,176 and 5,017,654.

The hydrosilylation catalyst is added to the pressure-sensitive adhesive composition in an amount sufficient to catalyze the hydrosilylation reaction, typically in an amount sufficient to provide from 10 ppm to 5,000 ppm by weight of platinum group metal.

Starting Material G) Solvent The pressure sensitive adhesive composition further comprises a solvent. The solvent may be an organic solvent. The organic solvent may be an alcohol, such as methanol, ethanol, isopropanol, butanol, or n-propanol; a ketone, such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; an aromatic hydrocarbon, such as benzene, toluene, or xylene; an aliphatic hydrocarbon, such as heptane, hexane, or octane; a glycol ether, 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; a halogenated hydrocarbon, such as dichloromethane, 1,1,1-trichloroethane, or methylene chloride; chloroform; dimethyl sulfoxide; dimethylformamide, acetonitrile; tetrahydrofuran, white spirits; mineral spirits, naphtha; n-methylpyrrolidone; or a combination thereof. Alternatively, the solvent may be selected from the group consisting of benzene, toluene, ethylbenzene, xylene, and combinations of two or more thereof.

The amount of solvent depends on a variety of factors, including the type of solvent selected and the amount and type of other starting materials selected for the pressure-sensitive adhesive composition. However, the amount of solvent may range from 10% to 90%, alternatively 20% to 60%, based on the total weight of all starting materials in the pressure-sensitive adhesive composition. The solvent may be added during preparation of the pressure-sensitive adhesive composition, for example, to aid in mixing and delivery. All or a portion of the solvent may be added with one of the other starting materials. For example, starting material A) and, if present, starting material B) may be dissolved in a solvent, such as an aromatic hydrocarbon, before combining with the other starting materials in the composition. All or a portion of the solvent may be optionally removed after preparing the pressure-sensitive adhesive composition.

Starting Material H) Additional Polyalkylhydrogensiloxanes The pressure sensitive adhesive compositions may optionally further comprise up to 20% by weight of starting material C) additional polyalkylhydrogensiloxanes having the unit formula (R ¹ ₃ SiO _1/2 ) ₂ (R ¹ HSiO _2/2 ) _z , where R ¹ is as defined above and subscript z is 200 to 250. Without being bound by theory, it is believed that starting material H) may be used to adjust the SiH:alkenyl ratio to the ranges described herein.

Methods for preparing polyalkylhydrogensiloxanes suitable for use as starting material H), such as the hydrolysis and condensation of alkylhalosiloxanes, are well known in the art. Examples of additional hydrosilylation reaction catalysts suitable for starting material H) include: H-1) trimethylsiloxy-terminated poly(methylhydrogensiloxanes);
H-2) trimethylsiloxy-terminated poly(dimethylsiloxane/methylhydrogensiloxane); and H-3) a combination of both H-1) and H-2).

When selecting starting materials for the pressure sensitive adhesive compositions described above, certain starting materials described herein may have multiple functions and therefore may overlap between types of starting materials. For example, certain alkoxysilanes may be useful as filler treatments and adhesion promoters. Certain particulates, such as carbon black, may be useful as fillers, pigments, and even flame retardants. When additional starting materials are added to the composition, the additional starting materials are different from each other and from the starting materials required for the composition.

The pressure sensitive adhesive composition can be prepared by a process that includes combining all of the starting materials by any convenient means, such as mixing at ambient or elevated temperature. Starting material E) acetylenic alcohol can be added before starting material F) platinum group metal catalyst, for example, when the pressure sensitive adhesive composition is prepared at elevated temperature and/or when the composition is prepared as a one-part composition.

Alternatively, the pressure-sensitive composition may be prepared as a multi-part composition, for example when the composition is stored for an extended period of time prior to use. In a multi-part composition, the starting material F) platinum group metal catalyst is stored in a separate part from the starting material having silicon-bonded hydrogen atoms, for example starting material C) polyalkylhydrogensiloxane and starting material H) (if present) and parts are combined parts immediately prior to using the pressure-sensitive adhesive composition. For example, a two-part composition may be prepared by combining starting materials including A) alkenyl-containing polydialkylsiloxane, C) polyalkylhydrogensiloxane (and starting material H), if present), and G) organic solvent, and optionally one or more other additional starting materials described above, by any convenient means, such as mixing, to form a base. The curing agent may be prepared by combining starting materials including A) alkenyl-containing polydialkylsiloxane, F) platinum group metal catalyst, and G) organic solvent, and optionally one or more other additional starting materials described above, by any convenient means, such as mixing. The starting materials may be mixed at ambient or elevated temperature. Starting material E) the acetylenic alcohol may be included in one or more of the base, the hardener part, or a separate additional part. Starting material D) the anchoring additive, if used, may be added to the base or as a separate additional part. Starting material B) the polyalkylsiloxane resin, if used, may be added to the base, the hardener part, or a separate additional part. When a two-part composition is used, the weight ratio of the amount of base to the amount of hardener part may range from 1:1 to 10:1. The pressure sensitive adhesive composition cures by a hydrosilylation reaction to form the pressure sensitive adhesive.

The above method may further include one or more additional steps. The pressure-sensitive adhesive composition prepared as described above may be used to form an adhesive article, such as a pressure-sensitive adhesive, on a substrate, prepared by curing the pressure-sensitive adhesive composition. The above method may further include applying the pressure-sensitive adhesive curable composition to a substrate.

Applying the pressure-sensitive adhesive curing composition to the substrate can be carried out by any convenient means. For example, the pressure-sensitive adhesive curing composition can be applied to the substrate by a gravure coater, an offset coater, an offset gravure coater, a roller coater, a reverse roller coater, an air knife coater, or a curtain coater.

The substrate can be any material capable of withstanding the curing conditions (described below) used to cure the pressure-sensitive adhesive curable composition to form a pressure-sensitive adhesive on the substrate. For example, any substrate capable of withstanding heat treatment at temperatures of 120° C. or higher, alternatively 150° C., is suitable. Examples of materials suitable for such substrates include plastic films such as polyimide (PI), polyetheretherketone (PEEK), polyethylenenaphthalate (PEN), liquid crystal polyarylate, polyamideimide (PAI), polyethersulfide (PES), or polyethyleneterephthalate (PET), or PE (polyethylene), or PP (polypropylene). Alternatively, the substrate can be a metal foil such as aluminum foil or copper foil. The thickness of the substrate is not critical, but the thickness can range from 5 micrometers to 300 micrometers.

To improve bonding of the pressure-sensitive adhesive to the substrate, the method may optionally further comprise treating the substrate prior to applying the pressure-sensitive adhesive composition. Treating the substrate may be carried out by any convenient means, such as applying a primer or subjecting the substrate to a corona discharge treatment, etching, or plasma treatment prior to applying the pressure-sensitive adhesive composition to the substrate.

Adhesive articles, such as protective films, can be prepared by applying the pressure-sensitive adhesive composition described above onto the substrate described above. The method may optionally further comprise removing all or a portion of the solvent before and/or during curing. Removal of the solvent may be carried out in any convenient manner, such as by heating the pressure-sensitive adhesive composition at a temperature that vaporizes the solvent without completely curing it, for example at a temperature of 70° C. to 120° C., alternatively 50° C. to 100° C., alternatively 70° C. to 80° C., for a time sufficient to remove all or a portion of the solvent (e.g., 30 seconds to 1 hour, alternatively 1 minute to 5 minutes). The method then further includes curing the pressure-sensitive adhesive composition (which may remove some or all of the solvent when a drying step is performed) by heating at room temperature or at a temperature of 140°C to 220°C, alternatively 150°C to 220°C, alternatively 160°C to 200°C, and alternatively 165°C to 180°C for a time sufficient to cure the pressure-sensitive adhesive curable composition (e.g., 30 seconds to 1 hour, alternatively 1 minute to 5 minutes). This forms a pressure-sensitive adhesive on the substrate. Drying and/or curing can be performed by placing the substrate in an oven. The amount of pressure-sensitive adhesive composition applied to the substrate depends on the particular application, but the amount can be sufficient that the thickness of the pressure-sensitive adhesive after curing can be 5 micrometers to 200 micrometers, and in the case of a protective film, the thickness can be 10 micrometers to 50 micrometers, alternatively 20 micrometers to 40 micrometers, alternatively 30 micrometers.

The methods described herein may optionally further include applying a removable release liner to the pressure-sensitive adhesive on the side opposite the substrate, for example, to protect the pressure-sensitive adhesive prior to use of the adhesive article.

The adhesive articles (e.g., protective films) prepared as described above are suitable for use in flexible OLED device fabrication processes as protective films with low adhesion, high adhesion stability, and/or low migration.

For example, a method for fabricating a flexible OLED device may include forming an OLED module on a surface of a substrate, e.g., a passivation layer on a surface of the OLED module opposite the substrate, and applying a protective film prepared as described herein to the surface of the passivation layer opposite the OLED module.

These examples are intended to illustrate some embodiments of the invention and should not be construed as limiting the scope of the invention as set forth in the claims. The starting materials used in these examples are listed in Table 1.

In the above table, "N/A" means not applicable and "Me" means methyl. DOWSIL™, SILASTIC™, and SYL-OFF™ products are commercially available from Dow Silicones Corporation, Midland, Michigan, USA.

Reference Example 1 (Preparation of Pressure Sensitive Adhesive Composition Samples)
Pressure sensitive adhesive composition samples were prepared by combining the starting materials shown in Table 1. First, 100 parts by weight of starting material A1) dimethylvinylsiloxy terminated poly(dimethylsiloxane/methylvinylsiloxane) copolymer was mixed with starting material G1) toluene solvent to make a 25 wt % solution. One or more of polyalkylhydrogensiloxanes (H1)-H4) and C1) were added to the mixture in the amounts shown in Tables 2 and 3 below. The amount of polyalkylhydrogensiloxane was sufficient to provide a SiH/Vi molar ratio of 0.5, 1, or 2 in the mixture. This ratio included the vinyl present in the vinyl-containing siloxane complexed platinum catalyst F1), which was added at the end of the procedure. Inhibitor E1) was added and the resulting combination was mixed well. After the mixture was homogenized, starting material (F1) was added to the mixture. The mixture was immediately and carefully mixed again to avoid heat generation. The resulting pressure sensitive adhesive composition sample was then ready for use. The amount (parts by weight) of each starting material in the samples is shown below in Tables 2 (comparative) and 3 (working), which also show the SiH/Vi ratio, total Pt content, and % solids (based on the weight of all starting materials excluding solvent).

Reference Example 2 - Preparation of PSA Sheet A pressure-sensitive adhesive composition sample was prepared as described in Reference Example 1 and coated onto a 50 um polyethylene terephthalate (PET) film to form a pressure-sensitive adhesive layer (having a thickness of 30 um after curing). A pressure-sensitive adhesive sheet was produced by heating the coated film at 150°C for 2 minutes. The substrate film (PET) is commercially available and sold under the trade name of Toray Advanced Material Korea (trade name SH-86, TAMK).

Reference Example 3 - Initial Adhesion Measurement Pressure sensitive adhesive tapes were formed by cutting the sheets obtained according to Reference Example 2 into strips of 1 inch width. The adhesive strength to stainless steel plate (SUS304) was measured according to the 180° peel test specified in ASTM D1000. Each tape was peeled from the peelable polyethylene terephthalate film and adhered to an adherend in the form of a mirror-finished stainless steel plate (SUS304) under a pressure of 2 kgf generated by a rubber roller. An initial adhesion higher than 2 gf/inch was defined as failure.

Reference Example 4 - Adhesion at 85°C/85% (Adhesion Stability)
Pressure-sensitive adhesive tapes were formed by cutting the sheets obtained according to Reference Example 2 into strips 1 inch wide. The adhesive strength to stainless steel plates (SUS304) was measured after aging according to the 180° peel test specified in ASTM D1000 as follows: Each tape was peeled off from the peelable polyethylene terephthalate film and adhered to an adherend in the form of a mirror-finished stainless steel plate (SUS304) under a pressure of 2 kgf generated by a rubber roller. The tapes were aged for 1 day (24 hours) and 3 days (72 hours) in an oven at 85°C/85% moisture. After cooling to room temperature, the adhesive strength was measured by peeling the pressure-sensitive adhesive tape from the adherend at an angle of 180° to the surface of the adherend using a tensile tester at a constant speed of 12 inches/min. (Testing equipment, AR-1000 (Chemininstrument Company)). The results are shown in Tables 2 and 3 below. In some applications, it may be desirable for adhesion to be <9 gf/in after 24 hours and <15 gf/in after 72 hours.

Reference Example 5 - Simple Scratch Test (Bur Test)
A pressure-sensitive adhesive sheet was prepared according to Reference Example 2. The pressure-sensitive adhesive surface was cut with a cutter, and the cross section was observed with the naked eye and under a microscope. If the cut edge looked clean and no dust was generated, it was considered to pass. If dust was observed on the edge or if burrs were observed on the edge, it was considered to fail.

Reference Example 6 - Simple rub-off test (fixation test)
The pressure-sensitive adhesive coated on PET was prepared according to Reference Example 2, and the adhesion of the pressure-sensitive adhesive was evaluated as follows: Cutting was performed: A 10 cm x 10 cm X mark was made only on the PSA by a cutter (be careful not to cut the bottom PET). The marked surface was rubbed vigorously with a finger. After rubbing for 30 seconds, the surface was observed to determine whether the PSA was rubbed off. If the PSA was rubbed off, the result was a failure.

Reference Example 7 - Residual Adhesive Residual Properties and Silicone Migration Properties (Residual Adhesion) After Exposure to 85°C/85% Conditions
Pressure-sensitive adhesive tapes were formed by cutting the sheets obtained according to Reference Example 2 into strips 1 inch wide. Each tape was peeled off from the peelable polyethylene terephthalate film and adhered to an adherend in the form of a mirror-finished stainless steel plate (SUS304) under a pressure of 2 kgf generated by a rubber roller. These were aged in an oven at 85°C/85% for 1 day (24 hours) and 3 days (72 hours). After cooling to room temperature, the PSA tape was removed from the mirror-finished stainless steel plate. Nitto 31B was adhered with a 2KG roller to the place where the Si tape was removed. After 30 minutes, the adhesion was measured by peeling the pressure-sensitive adhesive tape from the adherend at an angle of 180° to the surface of the adherend using a tensile tester at a constant speed of 12 inches/min. The results for each sample are also shown in Tables 2 and 3 below. "AF" in the tables indicates adhesive failure, which is not desirable for some applications.

Reference Example 8 - Burr Test Pressure-sensitive adhesive sheet samples prepared according to Reference Example 2 were used. A cutter was used to make cuts in the pressure-sensitive adhesive surface, which were visually observed with the naked eye and by microscope. If the edges of the cut appeared clean and no dust was generated, the sample was passed. If dust or debris was generated on the edge, or if a burr was observed, the sample was failed. The results for each sample are also shown in Tables 2 and 3 below.

In Tables 2 and 3, "N/D" means not detected due to adhesive migration; "AF" means adhesion failure, i.e., adhesive migrates to the substrate; "RF" means friction failure, i.e., adhesive rubs off due to stress; and "RF" means the result is "not applicable" to the present invention.

Example 9 (Comparative Example)
The sample was prepared according to the procedure of Reference Example 1, except that the starting material A2) was a comparative dimethylvinylsiloxy-terminated poly(dimethylsiloxane/methylvinylsiloxane) copolymer having both pendant and terminal vinyl groups, but with a vinyl content of 0.41%, DP>5,000, and a composition containing 100 parts by weight of 300 parts by weight of toluene, 0.748 parts by weight of starting material H4), 0.15 parts by weight of starting material E1), and 1.5 parts by weight of starting material F1). A silicone pressure-sensitive adhesive prepared by curing this composition failed the flash test when tested according to Reference Example 8. Without being bound by theory, it is believed that if the vinyl content of starting material A) in the pressure-sensitive adhesive composition was too high, the pressure-sensitive adhesive prepared therefrom failed the flash test.

Industrial Applicability The pressure-sensitive adhesive compositions described herein are cured to form pressure-sensitive adhesives suitable for use in flexible OLED device fabrication processes. The above examples have shown that the pressure-sensitive adhesives prepared by curing the above pressure-sensitive adhesive compositions can have an initial adhesion of <2 gf/inch on stainless steel (SUS) (when tested according to Reference Example 3), an adhesion of <9 gf/inch after 24 hours and an adhesion of <15 gf/inch after 72 hours when tested according to Reference Example 4. The pressure-sensitive adhesive compositions described herein can also be cured to form pressure-sensitive adhesives with residual adhesion of >300 gf/in after 24 hours and >250 g/in after 72 hours on SUS (when tested according to Reference Example 7). SUS is the industry standard for developing and testing pressure-sensitive adhesives. Thus, without wishing to be bound by theory, it is believed that the adhesion properties on SUS provide results comparable to substrates used in OLED fabrication processes, such as passivation layers, and it is anticipated that this combination of properties will enable the pressure sensitive adhesive film to be used as a protective film on a passivation layer during the fabrication of flexible OLED devices.

Furthermore, it has been surprisingly found that when a pressure-sensitive adhesive composition contains a poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer having an alkenyl content of 0.14% to <0.3%, the resulting pressure-sensitive adhesive passes the flash test (whereas a comparative pressure-sensitive adhesive containing an alternative functional polydialkylsiloxane having an alkenyl content >0.3% failed the flash test, as shown in Example 8).

Terminology Usage All amounts, ratios, and percentages are by weight unless the context of the specification dictates otherwise. The articles "a,""an," and "the" each refer to one or more, unless the context of the specification dictates otherwise. The disclosure of ranges includes the range itself and any subsumed within the range, as well as the endpoints. For example, the disclosure of a range of 0.14 to <0.3 not only includes the range 0.14 to <0.3, but also 0.15, 0.20, 0.26, and <0.3 individually, as well as any other numbers subsumed within the range. Further, for example, the disclosure of a range of 0.15 to <0.3 includes the subsets, for example, 0.15 to 0.21, 0.15 to 0.26, 0.202 to 0.26, and 0.202 to <0.3, as well as any other subset subsumed within that range. Similarly, the disclosure of a Markush group includes the entire group, as well as any individual members and subgroups subsumed therein. For example, disclosure of a Markush group of vinyl, allyl, or hexenyl includes individually the member vinyl; the subgroups vinyl and hexenyl; and any other individual members and subgroups subsumed therein.

The abbreviations used herein have the following meanings: "°C" and "°C" mean degrees Celsius, "DP" means degree of polymerization, "ETCH" means ethynylcyclohexanol, "GPC" means gel permeation chromatography, "GCMS" means gas chromatography mass spectrometry, "gf" means grams force, "hr" means hours, "KG" or "kg" means kilograms, and "kgf" means kilogram force. "min" means minutes, "Me" means methyl, "mPa s" means millipascal seconds, "OLED" means organic light emitting diode, "um" means micrometer, and "Vi" means vinyl.

EMBODIMENTS OF THE PRESENT DISCLOSURE In a first embodiment, a method for fabricating a flexible organic light emitting diode device comprises:
1) applying a pressure sensitive adhesive composition to a surface of a substrate;
2) curing the pressure-sensitive adhesive composition to form a pressure-sensitive adhesive film; and
3) applying the pressure sensitive adhesive film to a passivation layer within the device;
a pressure sensitive adhesive composition comprising:
A) 85 to 100 parts by weight of a poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer, the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer having silicon-bonded alkyl groups having 1 to 10 carbon atoms and silicon-bonded alkenyl groups having 2 to 6 carbon atoms, the alkenyl groups being present in an amount of 0.14% to <0.3%, based on the weight of the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer;
C) 0.1 to 5 parts by weight of a polyalkylhydrogensiloxane having the unit formula (R ¹ ₂ HSiO _1/2 ) ₂ (R ¹ ₂ SiO _2/2 ) _x (R ¹ HSiO _2/2 ) _y , where each R ¹ is an independently selected alkyl group of 1 to 10 carbon atoms, subscript x ≧ 0, subscript y ≧ 0, and the amount (x + y) is sufficient for the viscosity of the polyalkylhydrogensiloxane to be < 20 mPa s when measured at 25°;
F) a platinum group metal catalyst in an amount sufficient to provide a 10-5000 ppm concentration of Pt group metal in the composition;
E) 0.01 to 1 part by weight of acetylene alcohol;
G) 10% to 90% by weight of an organic solvent, based on the combined weight of all starting materials in the composition, provided that all starting materials in the combined composition have a molar ratio of silicon-bonded hydrogen atoms to silicon-bonded alkenyl groups (SiH:Alkenyl ratio) of 0.5:1 to 2:1.

In a second embodiment, in the method of the first embodiment, the starting material A) has characteristics selected from the group consisting of i) a number average molecular weight of 200,000 g/mol to 500,000 g/mol, ii) an alkenyl group content of 0.20% to 0.26%, and iii) both i) and ii).

In a third embodiment, in the method of the first or second embodiment, starting material A) comprises the average unit formula: (R ¹ ₂ R ² SiO _1/2 ) _d (R ¹ ₃ SiO _1/2 ) _e (R ¹ R ² SiO _2/2 ) _f (R ¹ ₂ SiO _2/2 ) _g , where each R ¹ is independently an alkyl group of 1 to 10 carbon atoms and each R ² is independently selected from R ¹ , OH, and an alkenyl group of 2 to 6 carbon atoms, subscript d≧0, subscript e≧0, subscript f>0, subscript g≧0, and where the amount (d+e)=2 and the amount (d+e+f+g) is from 4,500 to 5,000.

In a fourth embodiment, in the method of any one of the first to third embodiments, the starting material C) has properties selected from the group consisting of: i) a viscosity of 8 mPa·s to 16 mPa·s at 25°C; ii) a SiH content of >0% to <1%; and iii) both i) and ii).

In a fifth embodiment, in the method of any one of the first to fourth embodiments, the starting material F) is selected from the group consisting of (F-1) platinum group metals selected from platinum, rhodium, ruthenium, palladium, osmium, and iridium, (F-2) compounds of platinum group metals, (F-3) complexes of compounds and low molecular weight organopolysiloxanes, and (F-4) compounds (F-2) or complexes (F-3) microencapsulated in a matrix or core/shell structure.

In a sixth embodiment, in the method of any one of the first to fifth embodiments, the starting material E) is selected from the group consisting of (E-1) 1-ethynyl-1-cyclohexanol, (E-2) methylbutynol, (E-3) diallyl maleate, and (E-4) a combination of two or more of (E-1), (E-2) and (E-3). The starting material E) comprises ethynylcyclohexanol.

In a seventh embodiment, in the method of any one of the first to sixth embodiments, the starting material G) is selected from the group consisting of benzene, toluene, heptane, ethylbenzene, xylene, and combinations of two or more thereof.

In an eighth embodiment, in the method according to any one of the first to seventh embodiments, the pressure sensitive adhesive composition further comprises up to 20% of additional polyalkylhydrogensiloxanes having H) units of formula (R ¹ ₃ SiO _1/2 ) ₂ (R ¹ HSiO _2/2 ) _z , based on the weight of the starting material C), where subscript z is 200 to 250.

In a ninth embodiment, in the method of any one of the first through eighth embodiments, the pressure sensitive adhesive composition further comprises up to 15 parts by weight of B) a polyalkylsiloxane resin comprising units of the formula (R ¹ ₂ R ² SiO _1/2 ) _a (R ¹ ₃ SiO _1/2 ) _b (SiO _4/2 ) _c , where each R ¹ is independently an alkyl group of 1 to 10 carbon atoms and each R ² is independently selected from R ¹ , OH, and an alkenyl group of 2 to 6 carbon atoms, with subscript a≧0, subscript b≧0, subscript c>0, the amount (a+b)>0, and subscripts a, b, and c having values such that 0.9≦(a+b)/c≦1.2.

In a tenth embodiment, in any one of the methods of the first to ninth embodiments, the pressure-sensitive adhesive composition further comprises up to 1 part by weight of D) an anchoring additive.

In an eleventh embodiment, in the method of the tenth embodiment, the starting material D) is selected from the group consisting of (D-1) vinyltriacetoxysilane, (D-2) glycidoxypropyltrimethoxysilane, (D-3) a combination of (D-1) and (D-2), and (D-4) a combination of (D-3) and a polydimethylsiloxane terminated with hydroxyl groups, methoxy groups, or a polydimethylsiloxane terminated with both hydroxyl groups and methoxy groups.

In a twelfth embodiment, the method of any one of the first to eleventh embodiments further comprises removing all or a portion of the solvent from the pressure-sensitive adhesive composition prior to step 2).

In embodiment 13, the method of any one of embodiments 1 to 12 further comprises treating the substrate prior to step 1).

In a fourteenth embodiment, starting material A) does not contain silicon-bonded aromatic hydrocarbyl groups, starting material B), if present, does not contain silicon-bonded aromatic hydrocarbyl groups, starting material C) does not contain silicon-bonded aromatic hydrocarbyl groups, and starting material D), if present, does not contain silicon-bonded aromatic hydrocarbyl groups or two or more thereof in the nineteenth embodiment.

Claims (15)

1. A pressure sensitive adhesive composition comprising:
A) 85 to 100 parts by weight of a poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer having silicon-bonded alkyl groups having 1 to 10 carbon atoms and silicon-bonded alkenyl groups having 2 to 6 carbon atoms, said alkenyl groups being present in an amount of 0.14% to <0.3%, based on the weight of said poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer;
C) 0.1 to 5 parts by weight of a polyalkylhydrogensiloxane having the unit formula ( ^R12HSiO1 _{/ 2} ) ₂ ( ^R12SiO2 _{/2 ) x} ( ^R1HSiO2 _/2 ) _y , where each ^R1 is an independently selected alkyl group of 1 to 10 carbon atoms, subscript x>0, subscript y>0, and the amount (x+y) is sufficient for the viscosity of said polyalkylhydrogensiloxane to be <20 mPa·s when measured at 25° C. using a capillary viscometer;
F) a platinum group metal catalyst in an amount sufficient to provide a concentration of 10 to 5000 ppm Pt group metal in said composition;
E) 0.01 to 1 part by weight of acetylene alcohol;
G) 10% to 90% by weight of an organic solvent, based on the combined weight of all starting materials in said composition, with the proviso that all starting materials in said composition combined have a molar ratio of silicon-bonded hydrogen atoms to silicon-bonded alkenyl groups (SiH:alkenyl ratio) of 0.5:1 to 2:1. 2. The composition of claim 1, wherein said composition further comprises up to 20% based on the weight of starting material C), of additional polyalkylhydrogensiloxanes having H) units of formula (R ¹ ₃ SiO _1/2 ) ₂ (R ¹ HSiO _2/2 ) _z , where subscript z is 200-250. The composition of claim 1 or 2, wherein starting material C) has a silicon-bonded hydrogen (SiH) content of >0 to <1 wt.%. 4. The composition of claim 1, further comprising: B) up to 15 parts by weight of a polyalkylsiloxane resin comprising units of the formula (R ¹ ₂ R ³ SiO _1/2 ) _a (R ¹ ₃ SiO _1/2 ) _b (SiO _4/2 ) _c , where each R ¹ is independently an alkyl group of 1 to 10 carbon atoms and each R ³ is independently selected from R ¹ , OH, and an alkenyl group of 2 to 6 carbon atoms, subscript a≧0, subscript b≧0, subscript c>0, the amount (a+b)>0, and subscripts a, b, and c have values such that 0.9≦(a+b)/c≦1.2. The composition according to any one of claims 1 to 4, further comprising up to 1 part by weight of D) a fixing additive. The composition of claim 5, wherein the starting material D) is selected from the group consisting of D-1) vinyltriacetoxysilane, D-2) glycidoxypropyltrimethoxysilane, D-3) 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, D-4) a combination of two or more of D-1), D-2), and D-3), and D-5) a combination of any of D-1), D-2), D-3), and/or D-4) with a polydimethylsiloxane terminated with hydroxyl groups, methoxy groups, or both hydroxyl and methoxy groups. A) The composition of any one of claims 1 to 6, wherein the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer has >0.2% to 0.26% alkenyl groups. A) The composition of any one of claims 1 to 7, wherein the poly(dialkylsiloxane/alkylalkenylsiloxane) copolymer comprises the unit formula: (R ¹ ₂ R ² SiO _1/2 ) _d (R ¹ ₃ SiO _1/2 ) _e (R ¹ R ² SiO _2/2 ) _f (R ¹ ₂ SiO _2/2 ) _g , where each R ¹ is independently an alkyl group of 1 to 10 carbon atoms and each R ² is independently an alkenyl group of 2 to 6 carbon atoms, subscript d > 0, subscript e > 0, subscript f > 0, subscript g > 0, and where the amount (d + e) = 2 and the amount (d + e + f + g) is from 4,500 to 5,000. The composition according to any one of claims 1 to 8, wherein the starting material F) is selected from the group consisting of (F-1) a platinum group metal selected from platinum, rhodium, ruthenium, palladium, osmium, and iridium, (F-2) a compound of said platinum group metal, (F-3) a complex of said compound with a low molecular weight organopolysiloxane, and (F-4) said compound (F-2) or said complex (F-3) microencapsulated in a matrix or a core/shell structure. The composition according to any one of claims 1 to 9, wherein the starting material E) is selected from the group consisting of (E-1) 1-ethynyl-1-cyclohexanol, (E-2) methylbutynol, (E-3) diallyl maleate, and (E-4) a combination of two or more of (E-1), (E-2), and (E-3). The composition according to any one of claims 1 to 10, wherein the starting material G) is selected from the group consisting of benzene, toluene, heptane, ethylbenzene, xylene, and combinations of two or more thereof. The composition of any one of claims 1 to 11, wherein the composition is a multi-part composition comprising a base and a hardener portion, the base comprising starting materials A), C), and G), the hardener portion comprising starting materials A), F), and G), and the composition further comprising starting material E) in one or more of the base or a separate third portion. 1. A method for preparing a pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive film on a surface of a substrate, the method comprising:
Optionally, 1) treating the surface of the substrate;
2) applying a pressure-sensitive adhesive composition according to any one of claims 1 to 12 to the surface of the substrate;
Optionally, 3) removing all or a portion of the solvent; and
4) curing the pressure sensitive adhesive composition to form the pressure sensitive adhesive film on the surface of the substrate. A method for fabricating a flexible organic light emitting diode device, comprising performing the method steps of claim 13 to thereby prepare a pressure sensitive adhesive tape, and applying the pressure sensitive adhesive tape to a passivation layer in the device. 14. Use of the pressure sensitive adhesive tape prepared by the method of claim 13 for protection of a passivation layer in a flexible organic light emitting diode device.