Hydrogenated silanized pressure-sensitive adhesive composition containing 1-COD

Abstract

A one-component pressure-sensitive adhesive composition comprises: (a) a silicone resin; (b) a linear silicone containing an average of at least two terminal alkenyl groups per molecule; (c) a reactive diluent having terminal alkenyl groups; (d) a crosslinking agent having at least two hydrogenated silyl groups per molecule; (e) a 1-COD hydrogenated silanization catalyst; (f) optionally, a hydrogenated silanization inhibitor; and (g) a non-reactive organic solvent comprising less than 10% by weight of the one-component pressure-sensitive adhesive composition.

Description

Technical Field

[0001] The present invention relates to a hydrogenated silanized curable organosilicon pressure-sensitive adhesive composition comprising a platinum(II) ω-olefinic complex containing 1,5-cyclooctadiene, referred to as 1-COD, as a catalyst. Background Technology

[0002] Pressure-sensitive adhesive (PSA) compositions are curable compositions that form a PSA upon curing. Typically, PSA compositions are applied to a substrate and then cured to form a PSA on the substrate. A common type of curing chemistry for PSA compositions is hydrosilylation, in which organosilicones with carbon-carbon double bond (C=C) functional groups react with a crosslinking agent containing hydrosilyl (SiH) functional groups in the presence of a hydrosilylation catalyst. Karstedt catalysts are perhaps the most widely used hydrosilylation catalysts in these systems; however, there are challenges to overcome when using Karstedt catalysts. Karstedt catalysts tend to be highly efficient in inducing hydrosilylation reactions, meaning that the hydrosilylation reaction occurs rapidly in the presence of a Karstedt catalyst. Therefore, once the catalyst is introduced into the PSA composition, PSA compositions using Karstedt catalysts have a short processability time. Similarly, PSA compositions containing Karstedt catalysts cannot be easily compounded and stored for any reasonable period of time, which hinders the formulation of PSA compositions as single-component systems.

[0003] Inhibitors such as 1-ethynyl-1-cyclohexanol (ETCH) can be added to PSA compositions containing Karstedt catalysts to slow down the rapid curing reaction. ETCH inhibits the catalytic hydrosilylation reaction of the Karstedt catalyst at lower temperatures but allows the reaction to proceed at higher temperatures. The use of inhibitors presents its own challenges for PSA compositions containing Karstedt catalysts. Typically, the inhibitor-catalyst complex is insoluble in the components of the PSA composition, especially those compositions with little or no solvent. This incompatibility can lead to phase separation of the inhibitor / catalyst complex, or even precipitation from the PSA composition over time, resulting in a decrease in the reactivity of the PSA composition over time. This deactivation manifests as a shortened shelf life of the PSA composition as the inhibitor / catalyst separates from the PSA composition over time, and the usefulness of the PSA composition decreases due to reduced reactivity, preventing the PSA composition from curing completely (if any). In addition, the inhibitor / catalyst complex can cause undesirable discoloration of the PSA composition.

[0004] The aim is to enhance the controllability, flexibility, and ease of use of PSA compositions by identifying a PSA composition that can be formulated as a single-component system containing both reactants and catalysts, but can be formulated with inhibitors without experiencing a decrease in reactivity over time (storage stability) and without experiencing the degree of discoloration (color stability) experienced by similar PSA compositions containing Karstedt catalysts. Summary of the Invention

[0005] Surprisingly, this invention provides a single-component PSA composition that simultaneously contains reactants and a catalyst, yet can be formulated with an inhibitor without experiencing a decrease in reactivity over time (i.e., exhibiting shelf stability) and without discoloration in the presence of the inhibitor (i.e., exhibiting color stability). Even more advantageously and surprisingly, based on the weight of the PSA composition, the PSA composition of this invention can contain less than 10 wt%, or even less than 5 wt%, of a non-reactive organic solvent, and still achieve these results.

[0006] This invention stems from the discovery that these results unexpectedly occur when using "1-COD" as a hydrosilylation catalyst. "1-COD" is a platinum(II)ω-enyl complex with 1,5-cyclooctadiene, having the following structure ("Vi" is a vinyl group):

[0007]

[0008] 1-COD is a known catalyst for hydrogenation silylation reactions, but it is not known to solve all the problems discovered in this invention, particularly storage stability and color stability, not to mention in reactive compositions as complex as PSA compositions and in the presence of almost no non-reactive organic solvents.

[0009] In a first aspect, the present invention is a one-component pressure-sensitive adhesive composition comprising the following active component: (a) 50% to 80% by weight of an R3SiO2-containing... 1 / 2 and SiO 4 / 2 Organosilicon resins with siloxane units, wherein each R is independently selected from hydrocarbon groups having 1 to 20 carbons, wherein the organosilicon resin does not contain non-aromatic alkenyl groups, and SiO 4 / 2(a) Up to 5 mol% of oxygen atoms on the siloxane unit participate in the SiOZ bond, wherein Z is selected from hydrogen and alkyl groups having 1 to 6 carbon atoms; (b) 15 wt% to 40 wt% of a linear organosilicon, wherein each molecule of the linear organosilicon contains an average of at least two terminal alkenyl groups; (c) 0 wt% to 7 wt% of a reactive diluent having terminal alkenyl groups; (d) a crosslinking agent having at least two hydrosilyl groups per molecule, the concentration of which is sufficient to make the molar ratio of hydrosilyl to alkenyl groups in the one-component pressure-sensitive adhesive composition range from 1:1 to 40:1; (e) a 1-COD hydrosilylation catalyst, the concentration of which is sufficient to make the platinum concentration range from 15 parts by weight per million parts by weight of the reactive pressure-sensitive adhesive composition to 250 parts by weight per million parts by weight of the reactive pressure-sensitive adhesive composition; (f) 0% to 1% by weight of a hydrogenated silanization inhibitor; and (g) less than 10% by weight of a non-reactive organic solvent; wherein the weight percentage is relative to the weight of the one-component pressure-sensitive adhesive composition.

[0010] In a second aspect, the present invention is a method for preparing a pressure-sensitive adhesive, the method comprising the steps of: (a) providing a one-component pressure-sensitive adhesive composition according to any one of claims 1-6; and (b) heating the one-component pressure-sensitive adhesive composition to a temperature of at least 60 degrees Celsius and curing the one-component pressure-sensitive adhesive composition.

[0011] The compositions of the present invention can be used as PSA compositions, which can be used to produce PSA coatings. Detailed Implementation

[0012] When a date is not indicated by a test method number, the test method refers to the most recent test method as of the priority date of this document. References to test methods include references to both the testing association and the test method number. The following test method abbreviations and designations apply to this document: ASTM refers to ASTM International Society Methods; END refers to European Standards; DIN refers to the German Institute for Standardization; ISO refers to the International Organization for Standardization; and UL refers to Underwriters Laboratories.

[0013] Products identified by their trade names refer to compositions available under those trade names as of the priority date of this document.

[0014] "Multiple" means two or more. "And / or" means "and, or as an alternative." Unless otherwise specified, all ranges include the endpoints.

[0015] "Organosilicon" refers to polysiloxanes, which are molecules containing multiple siloxane units. Siloxane units are typically identified using the abbreviations M, D, T, and Q. M-type siloxane units refer to those with the chemical formula R... a 3SiO 1 / 2The unit. D-type siloxane units refer to those with the chemical formula R. a 2SiO 2 / 2 The unit. A T-type siloxane unit refers to a unit with the chemical formula R. a SiO 3 / 2 The Q-type siloxane unit refers to a unit with the chemical formula SiO. 4 / 2 The unit. In these general formulas, each R a Each time it appears, it is independently selected from hydrogen, a hydrocarbon group (substituted or unsubstituted), a hydroxyl group, an alkoxy group, or essentially any other group bonded to a silicon atom. O refers to an oxygen atom bonded to silicon that is shared with a silicon atom or a Z group (hydrogen or alkyl) of another siloxane unit. The subscript is a multiple of ½ to reflect that oxygen is bonded to this silicon atom and to another functional group, such as a -Z group or silicon atom, of another siloxane unit that is also a multiple of ½ in the denominator, and thus shares ownership with it—both siloxane units reflect ½ ownership of the same oxygen atom. The number in the oxygen subscript reflects how much oxygen is bonded to the specified silicon atom, which is also bonded to a silicon atom of another siloxane unit. Typically, there is a subscript associated with the siloxane unit itself to indicate the relative amount of siloxane units in the molecule. If the subscript associated with the siloxane unit is greater than one, then the subscript refers to the average number of those siloxane units in the molecule. If the subscript associated with a siloxane unit is less than one, then the subscript refers to the average molar ratio of the siloxane unit associated with that subscript to the total number of moles of all siloxane units in the molecule. Subscript one is usually not specified, so if a siloxane unit does not include a subscript, it should be understood to have subscript one. The chemical formula of organosilicones is usually listed in blocks for siloxane units, but this does not necessarily imply block polymerization (i.e., siloxane units exist as blocks in the molecule), but rather it is presented in blocks for convenience to indicate how much of each siloxane unit is present in the polymer in total.

[0016] "Resin-like polysiloxanes," also known as "silicone resins" or simply "resins," contain 30 mol% or more, and may contain 50 mol% or more, 70 mol% or more, 90 mol% or more, or even 100 mol% of the total of Q-type, T-type, or Q-type and T-type siloxane units. In contrast, "non-resin-like" organosilicones (which are often simply referred to as "polymers" or "linear" organosilicones, siloxanes, or polysiloxanes) contain less than 30 mol% of a combination of Q-type and T-type siloxane units, and typically contain only siloxane groups selected from M-type and D-type siloxane units.

[0017] The "hydrosilyl" functional group refers to a group with hydrogen atoms that are directly bonded to silicon atoms to form a SiH group.

[0018] The number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution of organosilicon resins were determined using gel phase chromatography (GPC) with ethyl acetate as solvent, employing an Agilent Technologies 1260 Infinity chromatograph. The chromatograph used two columns: an Agilent PLgel Mixed-D column and a PLgel Mixed-E column. The chromatograph was calibrated using polystyrene standards. Samples were prepared by dissolving the sample material (resin) in toluene (approximately 20 mg / mL) and immediately analyzing the material via GPC at a flow rate of 1 mL / min and a column temperature of 35 °C.

[0019] One-component PSA composition

[0020] In a first aspect, the present invention is a one-component pressure-sensitive adhesive (PSA) composition. A PSA composition is a composition curable into a pressure-sensitive adhesive. The PSA composition of the present invention can be cured using a hydrosilanization chemistry. The PSA composition of the present invention is a "one-component" PSA composition, meaning that all components of the PSA composition exist together as a fully formulated PSA composition without immediate reaction (i.e., it has a certain shelf stability). The "one-component" PSA composition contrasts with a "two-component" PSA composition, which preserves the reactive components of the PSA composition in two separate compositions during storage, and then mixes the two separate compositions together just before use to form a fully formulated PSA composition.

[0021] The one-component PSA composition of the present invention comprises: (a) an organosilicon resin; (b) a linear organosilicon; (c) an optional reactive diluent; (d) a crosslinking agent; (e) a hydrogen silanization catalyst; (f) optionally, a hydrogen silanization inhibitor; and (g) an organic solvent of less than 10% by weight based on the one-component PSA composition.

[0022] (a) Organosilicon resin

[0023] The organosilicon resin of the present invention contains R3SiO 1 / 2 and SiO 4 / 2The siloxane unit, wherein each R is independently selected from a hydrocarbon group having 1 to 20 carbon atoms. The R group may contain one or more, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or even ten or more carbon atoms, while simultaneously containing 20 or fewer and may contain 18 or fewer, 16 or fewer, 14 or fewer, 12 or fewer, or even ten or fewer carbon atoms. The silicone resin does not contain non-aromatic alkenyl groups and may not contain any alkenyl groups. The silicone resin may be made from R3SiO 1 / 2 and SiO 4 / 2 The siloxane unit composition makes it a "MQ" resin.

[0024] Regardless of whether the silicone resin is an MQ resin or contains siloxane units other than M and Q siloxane units, SiO 4 / 2 In a siloxane unit, up to 5 mol% of oxygen atoms participate in the SiOZ bond, where Z is selected from hydrogen and alkyl groups having 1 to 6 carbon atoms. This means that SiO 4 / 2 In siloxane units, 0 mol% or more, 1 mol% or more, 2 mol% or more, 3 mol% or more, or even 4 mol% or more, while 5 mol% or less, 4 mol% or less, 3 mol% or less, 2 mol% or less, or even 1 mol% or less of oxygen atoms participate in such SiOZ bonds (such as silanol bonds).

[0025] Using silicon-29 ( 29 The SiOZ content (“OZ content”) of the resin was determined by nuclear magnetic resonance (NMR) spectroscopy, expressed as a concentration in mol%. NMR spectra were collected using an Agilent 500 MHz DD2 (mi-MR-06) system equipped with a 16 mm organosilicon-free AutoX probe or a Varian Inova NMR (mi-MR-04) spectrometer with a proton operating frequency of 400 MHz. Samples were prepared in deuterated chloroform with 0.02 moles of chromium acetylacetone (III) (Cr(acac)3). The OZ content is the sum of the molar numbers of alkoxy and hydroxyl groups bonded to silicon atoms, expressed as a percentage relative to the molar number of silicon atoms in the molecule. The relative molar concentration of functional groups was determined by integrating peaks corresponding to different siloxane units (M, D, and T) based on predetermined attribution identifiers known in the art. 29 The OZ content is determined by Si NMR spectroscopy. The OZ content is the sum of the products of the molar concentration of each functional group and the number of OZ groups associated with each functional group.

[0026] Advantageously, the silicone resin has a weight-average molecular weight (Mw) in the range of 8,400 Daltons to 29,000 Daltons (Da). The Mw of the silicone resin can be 10,000 Da or greater, 12,000 Da or greater, 14,000 Da or greater, or even 16,000 or greater, while typically it is 29,000 Da or less, or even 27,000 Da or less, 25,000 Da or less, 230,000 Da or less, 21,000 Da or less, 19,000 Da or less, or even 17,000 or less.

[0027] A suitable silicone resin is a trimethylsilyl-terminated MQ resin with a Mn of about 3700 Daltons, a Mw of about 16,800 Daltons, and an OZ content of about 4.1 mol in the form of SiOH.

[0028] The concentration of the silicone resin in the PSA composition of the present invention is advantageously 50% by weight (wt%) or more of the single-component PSA composition, and may be 55 wt% or more, 60 wt% or more, 65 wt% or more, 70 wt% or more, or even 75 wt% or more, and is typically 80 wt% or less, and may be 75 wt% or less, 70 wt% or less, 65 wt% or less, 60 wt% or less, or even 55 wt% or less.

[0029] (b) Linear organosilicon

[0030] The linear organosilicon of the present invention has, on average, at least two terminal alkenyl groups per molecule. The terminal alkenyl groups are attached to the silicon atoms of the M-type siloxane unit. Advantageously, the linear organosilicon of the present invention has one or more alkenyl groups at different ends of the linear molecule, thereby forming alkenyl-terminated organosilicon. Advantageously, the alkenyl group is a vinyl group.

[0031] The linear organosilicon can be, for example, one or more combinations of vinyl-terminated polydimethylsiloxanes having the following chemical structures:

[0032]

[0033] in:

[0034] Vi refers to the vinyl group;

[0035] x and z are each independently averages within the range of 1 to 3, and can be one or more, or even two or more, simultaneously three or fewer, or even two or fewer; and

[0036] y has an average value in the range of 125 to 175, and can be 125 or greater, 130 or greater, 135 or greater, 140 or greater, 145 or greater, 150 or greater, 155 or greater, 160 or greater, 165 or greater, or even 170 or greater, while it is usually 175 or less, and can be 170 or less, 165 or less, 160 or less, 155 or less, or even 150 or less.

[0037] The linear organosilicon is advantageously present at a concentration of 15 wt% or higher relative to the weight of the single-component PSA composition, and may be present at a concentration of 20 wt% or higher, 25 wt% or higher, 30 wt% or higher, or even 35 wt% or higher, while it is present at a concentration of 40 wt% or lower, and may be present at a concentration of 35 wt% or lower, 30 wt% or lower, 25 wt% or lower, or even 20 wt% or lower.

[0038] (c) Reactive diluent

[0039] The single-component PSA composition of the present invention may or may not contain a reactive diluent. The reactive diluent is advantageously an unsaturated hydrocarbon, typically a straight-chain olefin. Preferably, the reactive diluent is a terminally unsaturated straight-chain hydrocarbon selected from any combination of one or more compounds having the following chemical structures:

[0040]

[0041] The subscript n has an average value that is usually 5 or greater, 6 or greater, 7 or greater, 8 or greater, 9 or greater, 10 or greater, 11 or greater, 12 or greater, 14 or greater, 16 or greater, and can be 18 or greater, while usually 20 or less, and can be 18 or less, 16 or less, 14 or less, 13 or less, 12 or less, or even 11 or less.

[0042] Relative to the weight of the single-component PSA composition of the present invention, the concentration of the reactive diluent in the single-component PSA composition is typically 0 wt% or greater, and may be 1 wt% or greater, 2 wt% or greater, 3 wt% or greater, 4 wt% or greater, 5 wt% or greater, or even 6 wt% or greater, while typically 10 wt% or less, and may be 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, or even 1 wt% or less.

[0043] (d) Crosslinking agent

[0044] The single-component PSA composition of the present invention comprises a crosslinking agent. Each molecule of the crosslinking agent has an average of at least two hydrogenated silyl (SiH) groups. Advantageously, the crosslinking agent is a linear organosilicon, and even more advantageously, a linear organosilicon having side SiH groups rather than terminal SiH groups. The side SiH groups are located on siloxane units other than M-type siloxane units.

[0045] The crosslinking agent can be a trimethylsiloxy-terminated polymethylhydrosiloxane copolymer. Trimethylsiloxy-terminated polymethylhydrosiloxane copolymers may have the following chemical structures:

[0046]

[0047] in:

[0048] “Me” refers to the methyl group;

[0049] The subscript 'a' typically has an average value of 1 or greater, and can be 2 or greater, even 3 or greater; it is also typically 10 or less, and can be 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, even 4 or less; and

[0050] The subscript b typically has an average value of 2 or greater, and can be 3 or greater, 4 or greater, 5 or greater, or even 6 or greater, while it is typically 10 or less, and can be 9 or less, 8 or less, or even 7 or less.

[0051] The concentration of the crosslinking agent in the one-component PSA composition is sufficient to make the molar ratio of SiH groups (from the crosslinking agent) to alkenyl groups in the one-component PSA composition range from 1:1 to 40:1, and can be 1:1 or greater, 2:1 or greater, 3:1 or greater, 4:1 or greater, 5:1 or greater, 6:1 or greater, 7:1 or greater, 8:1 or greater, 9:1 or greater, 10:1 or greater, 15:1 or greater, 20:1 or greater, 25:1 or greater, 30:1 or greater, or even 35:1 or greater, while being 40:1 or less, and can be 35:1 or less, 30:1 or less, 25:1 or less, 20:1 or less, 15:1 or less, 10:1 or less, or even 5:1 or less.

[0052] (e) Hydrosilylation catalyst

[0053] The one-component PSA composition of the present invention contains 1-COD as a hydrogen silylation catalyst. Surprisingly, the present invention stems at least in part from the discovery of the remarkable benefits of using 1-COD as a hydrogen silylation catalyst in a one-component PSA composition. One surprising result is that the one-component PSA composition can simultaneously contain a hydrogen silylation inhibitor and a 1-COD hydrogen silylation catalyst while maintaining reactivity to hydrogen silylation over time. Furthermore, the one-component PSA composition of the present invention does not undergo discoloration in the presence of the inhibitor, a problem present in other platinum-based hydrogen silylation catalysts.

[0054] The concentration of the 1-COD hydrogen silanization catalyst in the single-component PSA composition of the present invention is sufficient to make the platinum concentration range from 15 parts by weight per million parts by weight of the single-component PSA composition to 250 parts by weight per million parts by weight of the single-component PSA composition (PPM), and is sufficient to make the platinum concentration 15 PPM or greater, 20 PPM or greater, 25 PPM or greater, 50 PPM or greater, 75 PPM or greater, 100 PPM or greater, 125 PPM or greater, 150 PPM or greater, 175 PPM or greater, 200 PPM or greater, or even 225 PPM or greater, while being 250 PPM or less, or even 200 PPM or less, 190 PPM or less, 180 PPM or less, 170 PPM or less, 160 PPM or less, or even 155 PPM or less.

[0055] The single-component PSA composition may be, and advantageously does not contain, platinum hydrosilylation catalysts other than 1-COD, such as Karstedt catalysts.

[0056] (f) Hydrosilylation inhibitors

[0057] The one-component PSA compositions of the present invention can and advantageously do contain a hydrosilylation inhibitor. To suppress gelation of the one-component PSA composition during storage, a hydrosilylation inhibitor may be desirable in slowing down or delaying the reactivity of the one-component PSA composition. However, as previously described herein, a combination of a hydrosilylation inhibitor and a platinum-containing hydrosilylation catalyst can also lead to detrimental effects, such as discoloration or reduced reactivity of the one-component PSA composition containing such a combination. Surprisingly, the one-component PSA compositions of the present invention can contain both a hydrosilylation inhibitor and a 1-COD hydrosilylation catalyst without resulting in discoloration or a significant reduction in reactivity.

[0058] Examples of suitable hydrosilylation inhibitors include any combination of one or more of the following: acetylene compounds, such as 2-methyl-3-butyn-2-ol; 3-methyl-1-butyn-3-ol; 3,5-dimethyl-1-hexyn-3-ol; 2-phenyl-3-butyn-2-ol; 3-phenyl-1-butyn-3-ol; 1-ethynyl-1-cyclohexanol; 1,1-dimethyl-2-propynyl)oxy)trimethylsilane; methyl(tris(1,1-dimethyl-2-propynyloxy))silane; And 1-ethynyl-1-cyclohexanol (ETCH); enynylene compounds, such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; triazoles, such as benzotriazoles; hydrazine-based compounds; phosphine-based compounds; thiol-based compounds; cycloalkenylsiloxanes, including methylvinylcyclosiloxanes, such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane.

[0059] The concentration of the hydrosilylation inhibitor relative to the weight of the single-component PSA composition is 0 wt% or greater, and may be 0.05 wt% or greater, 0.10 wt% or greater, 0.15 wt% or greater, 0.20 wt% or greater, 0.25 wt% or greater, or even 0.29 wt% or greater, while typically 1 wt% or less, and may be 0.90 wt% or less, 0.80 wt% or less, 0.70 wt% or less, 0.60 wt% or less, 0.50 wt% or less, 0.40 wt% or less, or even 0.30 wt% or less.

[0060] (g) Non-reactive organic solvents

[0061] The single-component PSA compositions of the present invention may contain very little non-reactive organic solvent, making them desirable in applications where residual organic solvent is undesirable. Non-reactive organic solvents are organic solvents that do not participate in the hydrosilylation reaction. For example, reactive diluents participate in the hydrosilylation reaction and therefore do not meet the criteria for non-reactive organic solvents.

[0062] Non-reactive organic solvents can be aromatic or aliphatic. Examples of aromatic non-reactive organic solvents include benzene, toluene, xylene, and combinations thereof. Examples of aliphatic non-reactive organic solvents include pentane, hexane, heptane, octane, nonane, decane, and combinations thereof.

[0063] The one-component PSA composition of the present invention may contain less than 10 wt% of a non-reactive organic solvent relative to the weight of the one-component PSA composition, and preferably contains 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, or even 1 wt% or less of a non-reactive organic solvent. The one-component PSA composition of the present invention may be free of non-reactive organic solvents.

[0064] Methods for preparing PSA

[0065] In a second aspect, the present invention provides a method for preparing PSA, the method comprising the steps of: (a) providing a one-component PSA composition according to the first aspect of the invention; and (b) heating the one-component PSA composition to a temperature of at least 60°C and curing the one-component PSA composition. Preferably, the one-component PSA composition in step (b) is heated to a temperature of 80°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, or even 150°C or higher, while typically heated to a temperature of 250°C or lower, preferably 200°C or lower, or even 180°C or lower, to cure the one-component PSA composition.

[0066] The second aspect of the method may further include applying a one-component PSA composition onto a substrate after step (a) and before step (b). This additional step produces a cured PSA coating on the substrate.

[0067] Example

[0068] Table 1 lists the components used in this section for sample preparation.

[0069]

[0070] PSA raw material mixture

[0071] A PSA feedstock mixture was prepared by combining 287.22 g of silicone resin, 107.02 g of linear silicone, and 14.63 g of reactive diluent into a single-necked 1 L flask. The flask was loaded onto a rotary evaporator equipped with a dry ice condenser and a hot oil bath set at 150 °C. The flask was evacuated (pressure <133 Pascals) while rotating at 25 rpm for 1 hour to vaporize volatiles such as non-reactive organic solvents.

[0072] catalyst solution

[0073] A reference catalyst solution was prepared by combining 0.501 g of Karstedt catalyst with 22.104 g of solvent.

[0074] A 1-COD catalyst solution was prepared by combining 0.501 g of 1-COD catalyst with 36.88 g of solvent.

[0075] PSA intermediate composition

[0076] A baseline PSA intermediate composition was prepared by combining 250.00 g of PSA feedstock mixture, 0.650 g of inhibitor and 8.00 g of baseline catalyst solution.

[0077] A 1-COD PSA intermediate composition was prepared by combining 250.00 g of PSA feedstock mixture, 0.642 g of inhibitor and 8.02 g of 1-COD catalyst solution.

[0078] Reference PSA composition—Karstedt catalyst

[0079] A single-component PSA composition was prepared by combining 26.02 g of a baseline PSA intermediate composition with 1.43 g of a crosslinking agent.

[0080] The PSA composition of the present invention—1-COD catalyst

[0081] A one-component PSA composition was prepared by combining 26.02 g of 1-COD PSA intermediate composition and 1.43 g of crosslinking agent.

[0082] Table 2 defines the composition of the reference PSA composition and the PSA composition of the present invention, showing the amount of the components expressed in grams (g) and wt% values.

[0083]

[0084] Characterization of single-component PSA compositions

[0085] The following procedures were used to characterize the color stability, reactive stability, initial tack, and bond strength of the reference PSA composition and the PSA composition of the present invention.

[0086] Color stability

[0087] The color of each PSA composition was monitored over time to determine if the color changed.

[0088] To understand the compatibility between the catalyst and the inhibitor, a PSA feedstock mixture was combined and mixed with a conventional or 1-COD catalyst solution and an inhibitor (as applicable) to obtain a mixture. Each mixture was placed in a capped vial and aged in air at room temperature. The color change of each mixture over time was visually monitored. At certain times, as shown in Tables 3 (and 4 for reactivity stability), a crosslinking agent was added to each mixture to provide a baseline PSA composition and the PSA composition of the present invention, and the compositions were mixed on a dental mixer at 3500 RPM for 30 seconds. Each composition was then analyzed by differential scanning calorimetry (DSC), and its appearance over time was visually examined. DSC was measured by heating each sample composition from 40°C to 200°C under N2 protection via a TA DSC-2500 DSC. In each of these compositions, the platinum content was the same, at 150-151 PPM, and the total ratio of silicon-bonded hydrogen atoms to silicon-bonded vinyl groups was the same, at 1.9 / 1 mol / mol (SiH vs. SiVi). Tables 3 and 4 below describe the color changes and DSC data of the baseline PSA composition and the PSA composition of the present invention over time intervals, respectively.

[0089] The results of the color stability test are shown in Table 3. Ideally, the composition begins and remains nearly colorless. As shown in Table 3, the combination of the reference catalyst solution and the inhibitor resulted in undesirable precipitation and color change in the reference PSA composition over time, which is undesirable and problematic throughout the anti-stick coating industry. In contrast, no significant color change or precipitation over time was observed in the case of the 1-COD catalyst solution and the inhibitor, resulting in the transparent PSA composition of the present invention.

[0090]

[0091] Reactivity and stability

[0092] The stability of the cured properties of PSA compositions is also critical for industrial applications. Therefore, the reactivity of PSA compositions was evaluated using DSC characterization to determine whether they retain reactivity over time. This evaluation determined the storage stability of the PSA compositions in terms of hydrogenation silylation reactivity—whether the reactivity of the PSA compositions decreases over time.

[0093] Differential scanning calorimetry (DSC) is a powerful technique for analyzing the reactivity of curable coating systems. It measures the heat flux associated with thermal transformations within the material, providing insights into the material's curing behavior. When applied to curable coating systems, DSC can measure parameters such as peak temperature (T0). 峰) and 95% conversion temperature (T 95 This provides valuable information about the curing process. 峰 This represents the maximum heat flux or peak temperature observed during the curing process of the coating system. It corresponds to the point where the curing reaction is at its most active or exothermic, indicating the maximum rate of reaction and energy release during curing. 95 This indicates the temperature at which 95% of the conversion or curing process occurs. It reflects the point at which most of the material has undergone the curing reaction, marking the near completion of the curing process. By analyzing these parameters using DSC, the reactivity and curing behavior of the coating system can be evaluated. Understanding T 峰 and T 95 This helps to gain a deeper understanding of the responsiveness of the tested PSA system.

[0094] As shown in Table 4, the curing properties of the baseline PSA composition, which includes a mixture of conventional catalysts and inhibitors, deteriorate progressively with aging. 峰 and T 95 Both increased significantly over time. Furthermore, color change and precipitation also increased accordingly. Conversely, the catalyst and inhibitor of the present invention do not have compatibility issues; as demonstrated by aging of the PSA composition of the present invention containing a mixture of 1-COD catalyst and inhibitor, its curing properties did not change over time (T0). 峰 and T 95 Both remain almost unchanged.

[0095]

[0096] Initial tack and bond strength

[0097] The PSA composition was confirmed to be usable as a pressure-sensitive adhesive after curing by evaluating its initial tack and bond strength in the following tests.

[0098] For each of the benchmark and the PSA compositions of this invention, a PSA composition film was coated onto a 2-mil polyester (PET) sheet using a 1.5-mil coating rod on a vacuum coating plate. Each PSA composition film was cured at 150°C for 5 minutes. Prior to testing, the cured samples were aged at 21°C and 50% relative humidity for 24 hours. The cured PSA film samples on the PET sheet were then cut into 1-inch wide strips for initial tack and bond strength testing.

[0099] Initial tack test

[0100] Initial tack test was performed according to ASTM D2979. The sample was tested on a PT-1000 probe initial tack tester with a dwell time of 1.0 second. Ten measurements were performed, discarding high and low values, and then averaging the remaining eight measurements to obtain the initial tack value (grams).

[0101] The initial tack test results are provided in Table 5. PSA needs to maintain an initial tack greater than 100 grams to achieve optimal performance. The results show that both the PSA composition of this invention and the benchmark PSA meet this threshold.

[0102]

[0103] Bond strength test

[0104] Adhesion strength was tested according to the PSTC-101 standard using the peel bond strength (180°) method. A sample strip (5 cm × 15 cm; 2 inch × 6 inch) was applied to a clean stainless steel panel using a 2 kg roller. The sample was allowed to remain at 21°C and 50% relative humidity for 20 minutes. The sample was evaluated using a TMI peel and bond strength tester at a rate of 30.5 cm (12 inches) / min with a 180° peel angle. The average of three measurements for each sample was taken, and the results were reported in grams per inch (g / in).

[0105] The bond strength test results are provided in Table 6. PSA needs to maintain a bond strength greater than 1000 g / in for optimal performance. The results show that both the PSA composition of this invention and the benchmark PSA meet this threshold.

[0106]

Claims

1. A one-component pressure-sensitive adhesive composition, said one-component pressure-sensitive adhesive composition comprising the following active components: (a) 50% to 80% by weight of R3SiO 1 / 2 and SiO 4 / 2 Organosilicon resins with siloxane units, wherein each R is independently selected from hydrocarbon groups having 1 to 20 carbons, wherein the organosilicon resin does not contain non-aromatic alkenyl groups, and the SiO 4 / 2 Up to 5 mol% of oxygen atoms on the siloxane unit participate in the SiOZ bond, where Z is selected from hydrogen and alkyl groups having 1 to 6 carbon atoms; (b) 15% to 40% by weight of linear organosilicon, wherein each molecule of the linear organosilicon contains an average of at least two terminal alkenyl groups; (c) 0% to 7% by weight of a reactive diluent having terminal alkenyl groups; (d) A crosslinking agent having at least two silyl groups per molecule, the concentration of which is sufficient to make the molar ratio of silyl groups to alkenyl groups in the one-component pressure-sensitive adhesive composition in the range of 1:1 to 40:

1. (e) 1-COD hydrogenation silanization catalyst, the concentration of which is sufficient to allow the platinum concentration to be in the range of 15 parts by weight per million parts by weight of the reactive pressure-sensitive adhesive composition to 250 parts by weight per million parts by weight of the reactive pressure-sensitive adhesive composition. (f) 0% to 1% by weight of a hydrosilylation inhibitor; and (g) Less than 10% by weight of non-reactive organic solvents; The weight percentage values ​​are relative to the weight of the one-component pressure-sensitive adhesive composition.

2. The one-component pressure-sensitive adhesive composition according to claim 1, wherein the one-component pressure-sensitive adhesive composition comprises 0.05% to 1% by weight of a hydrogenated silanization inhibitor based on the weight of the one-component pressure-sensitive adhesive composition.

3. The one-component pressure-sensitive adhesive composition according to any of the preceding claims, wherein: (a) The linear organosilicon is a vinyl-terminated polydimethylsiloxane; (b) The reactive diluent is a straight-chain olefin; and (c) The crosslinking agent is a trimethylsiloxy-terminated polydimethylsiloxane-polymethylhydrosiloxane copolymer.

4. The one-component pressure-sensitive adhesive composition according to any of the preceding claims, wherein the silicone resin is an MQ resin with a weight-average molecular weight in the range of 8,400 Daltons to 29,000 Daltons and has a silanol content of 4 mol%.

5. The one-component pressure-sensitive adhesive composition according to any of the preceding claims, wherein the linear organosilicon containing at least two terminal alkenyl groups per molecule has the following chemical structure: Vi x (CH3) (3-x) SiO[(CH3)2SiO] y SiVi z (CH3) (3-z) , where Vi refers to the vinyl group, x and z are each independently values ​​in the range of 1 to 3, and y is a value in the range of 125 to 175.

6. The one-component pressure-sensitive adhesive composition according to any one of the preceding claims, wherein the crosslinking agent has the following chemical composition: (CH3)3SiO[(CH3)2SiO] a [(CH3)HSiO] b Si(CH3)3, wherein subscript a has an average value in the range of 2 to 5, and subscript b has an average value in the range of 5 to 8.

7. The one-component pressure-sensitive adhesive composition according to any of the preceding claims, wherein the one-component pressure-sensitive adhesive composition is free of platinum hydrosilaneization catalysts other than 1-COD.

8. A method for preparing a pressure-sensitive adhesive, the method comprising the following steps: (a) A single-component pressure-sensitive adhesive composition according to any one of claims 1 to 6 is provided; as well as (b) Heating the one-component pressure-sensitive adhesive composition to a temperature of at least 60 degrees Celsius and curing the one-component pressure-sensitive adhesive composition.

9. The method of claim 8, further comprising coating the one-component pressure-sensitive adhesive composition onto a substrate after step (a) and before step (b).

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