Solventless pressure sensitive adhesive composition

Abstract

A method for producing a solvent-free pressure-sensitive adhesive composition, the method comprising mixing (A) a solid polyorganosilicate resin component with (B) an aliphatically unsaturated polydiorganosiloxane (B-1), a branched polyorganosiloxane (B-2), or a mixture of (B-1) and (B-2) at a temperature, followed by cooling. The solvent-free pressure-sensitive adhesive composition produced by the method has a low viscosity and can be cured to form a pressure-sensitive adhesive. The pressure-sensitive adhesive is suitable for use in protective film applications.

Description

Technical Field

[0001] This invention relates to a solvent-free pressure-sensitive adhesive composition and a method for preparing the pressure-sensitive adhesive composition. Background Technology

[0002] Polysilicate resins are solid at room temperature. In the absence of solvents, polysilicate resins are typically in powder or flake form, making them difficult to blend uniformly with other components when preparing silicone pressure-sensitive adhesive (PSA) compositions. Attempts to manufacture solvent-free PSA compositions typically involve dissolving the polysilicate resin in a solvent, or combining the polysilicate resin with other silicone components in a solvent, followed by solvent removal. Solvent removal steps (e.g., stripping) increase manufacturing and equipment costs, and the resulting compositions typically inherently contain more than 1,000 parts per million (ppm) of residual solvent. Furthermore, relatively low viscosity is desirable for certain applications, such as for protective films, for example, a viscosity of less than 5,000 mPa·s at room temperature. However, commercially available solvent-free PSA compositions typically have high viscosity, making it difficult to directly apply such compositions to substrates. In such cases, consumers still need to dilute the PSA composition with a solvent upon receipt and before use.

[0003] It is desirable to discover a method for preparing solvent-free PSA compositions that are suitable for use in protective films for electronic applications without the aforementioned problems. Summary of the Invention

[0004] The present invention solves the problem of finding solvent-free pressure-sensitive adhesive (PSA) compositions that do not have the above-mentioned problems.

[0005] This invention provides a novel method for preparing solvent-free PSA compositions, comprising preparing a silicone-based portion having a viscosity of less than 5,000 mPa·s at room temperature. The resulting solvent-free PSA composition of this invention can be directly applied to a substrate and cured to form a pressure-sensitive adhesive (PSA). PSAs can provide desired coating appearance and adhesive strength, particularly suitable for protective film applications, for example, peel strength of 20 g / in or less. Viscosity and adhesive strength properties can be measured according to the test methods described in the Examples section below.

[0006] In a first aspect, the present invention provides a method for preparing a solvent-free pressure-sensitive adhesive composition. The method includes:

[0007] (i) Providing a starting material (A) of solid polyorganosilicon component, comprising:

[0008] (A-1) A solid end-capping resin having a unitary formula (I-1) in a weight of greater than 30% to 100% by weight of the starting material (A):

[0009] (R M 3SiO 1 / 2 ) a (SiO 4 / 2 ) b Z c

[0010] Each R M Independently, each Z is a monovalent hydrocarbon group with 1 to 20 carbon atoms; each Z is independently a hydrolyzable group selected from the group consisting of alkoxy, hydroxyl, or mixtures thereof; c is 0 to a value sufficient to impart a hydrolyzable group content of up to 2% by weight based on the weight of the end-capping resin; and a and b have values ​​such that a > 4, b > 0, and the value of (a + b) is sufficient to impart a number average molecular weight of 500 g / mol to 8,000 g / mol to the end-capping resin; and

[0011] (A-2) Solid uncapped resin having unit formula (I-2) in a weight of 0 to less than 70% by weight of starting material (A):

[0012] (R M 3SiO 1 / 2 ) a’ (SiO 4 / 2 ) b’ Z c’

[0013] Where R M As described above, Z and a' and b' have values ​​such that a'>4, b'>0, and (a'+b') is sufficient to impart a number-average molecular weight of 500 g / mol to 8,000 g / mol to the uncapped resin; and c has a value sufficient to impart a hydrolyzable group content of >2% to 10% by weight to the uncapped resin based on the weight of the uncapped resin.

[0014] (ii) Mix the starting material (A) with the starting material (B) and optional starting material (C) at a temperature of 100°C or higher;

[0015] The starting material (B) is an aliphatic unsaturated polydiorganosiloxane (B-1), a branched polyorganosiloxane (B-2), or a mixture of (B-1) and (B-2).

[0016] Among them, the aliphatic unsaturated polydiorganosiloxane (B-1) contains unit formula (II-1):

[0017] (R 1 2R 2 SiO1 / 2 ) x (R 1 3SiO 1 / 2 ) y (R 1 R 2 SiO 2 / 2 ) z (R 1 2SiO 2 / 2 ) w

[0018] Each R 1 Independently, a monovalent hydrocarbon group of 1 to 20 carbon atoms without aliphatic unsaturated groups; each R 2 Independently, it is a monovalent aliphatic unsaturated hydrocarbon group with 2 to 20 carbon atoms; the values ​​of x, y, z, and w are such that x>0, y≥0, (x+y)=2, z≥0, w≥0, (w+z)>0, and the value of (x+y+z+w) is sufficient to give the aliphatic unsaturated polydiorganosiloxane a number average molecular weight of 5,000 g / mol to 50,000 g / mol;

[0019] Among them, the branched polyorganosiloxane (B-2) contains unit formula (II-2):

[0020] (R 1 3SiO 1 / 2 ) g (R 1 2R 2 SiO 1 / 2 ) h (R 1 2SiO 2 / 2 ) i (SiO 4 / 2 )

[0021] Where R 1 and R 2 As described above, and the values ​​of g, h, and i are such that 2≥g≥0, 4≥h≥0, 995≥i≥4, (g+h)=4, and the value of (g+h+i) is sufficient to give the branched polyorganosiloxane a number average molecular weight of 5,000 g / mol to 50,000 g / mol;

[0022] The starting material (C) is a polydiorganosiloxane resin with unit formula (III):

[0023] (R 1 2R G SiO 1 / 2 )2(R 1 2SiO 2 / 2 ) d

[0024] Where R 1 As mentioned above; each R G Independently, it is a monovalent aliphatic unsaturated hydrocarbon group, hydroxyl group, or combination thereof, consisting of 2 to 20 carbon atoms; and d has a number-average molecular weight value sufficient to impart a polydiorganosiloxane resin of 300,000 g / mol or greater;

[0025] The starting substances (A), (B) and (C) are present in an amount sufficient to provide 0.1 to 1.2 of the amount of starting substance (A) to the combined amount of starting substance (B) and, if present, starting substance (C).

[0026] (iii) Cool the mixture obtained in step (ii) to form an organosilicon-based fraction with a viscosity of less than 5,000 mPa·s at room temperature; and

[0027] (iv) The silicone-based material obtained in step (iii) is blended with starting material (D) polyorganohydrosiloxane, starting material (E) hydrosilylation catalyst, optional starting material (F) hydrosilylation inhibitor, and optional starting material (G) fixation additive to form a solvent-free pressure-sensitive adhesive composition.

[0028] In a second aspect, the present invention provides a solvent-free pressure-sensitive adhesive composition prepared by the method of the first aspect.

[0029] In a third aspect, the present invention provides a method for preparing an adhesive article, the method comprising:

[0030] Optionally (1) the surface of the substrate is treated.

[0031] (2) Applying the solvent-free pressure-sensitive adhesive composition of the second aspect to the surface of the substrate, and

[0032] (3) Curing the solvent-free pressure-sensitive adhesive composition. Detailed Implementation

[0033] "Solid" means that the resin or polymer is solid at room temperature (23±2 degrees Celsius (°C)).

[0034] “Alkyl” in this document means a cyclic, branched, or unbranched saturated monovalent hydrocarbon group. Examples of alkyl groups include 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, as well as branched alkyl groups with six or more carbon atoms; and cyclic alkyl groups such as cyclopentyl and cyclohexyl.

[0035] In this document, "aryl" refers to a cyclic, fully unsaturated hydrocarbon group. Examples of aryl groups include, but are not limited to, cyclopentadienyl, phenyl, anthraceneyl, and naphthyl. Monocyclic aryl groups may have 5 to 9, 6 to 7, or 5 to 6 carbon atoms. Polycyclic aryl groups may have 10 to 17, 10 to 14, or 12 to 14 carbon atoms.

[0036] "Aryl group" in this document means an alkyl group having a side-chain aryl group and / or a terminal aryl group, or an aryl group having a side-chain alkyl group. Exemplary aryl groups include tolyl, xylyl, benzyl, phenethyl, phenylpropyl, and phenylbutyl.

[0037] In this article, "alkenyl" refers to a branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds.

[0038] A method for preparing the solvent-free PSA composition of the present invention includes (i) providing a starting material (A), a starting material (B), and optionally a starting material (C). The starting material (A) used in the present invention is a solid polyorganosilicate resin component comprising, based on the weight of the starting material (A), greater than 30% to 100% by weight of (A-1) solid end-capped resin and 0 to less than 70% by weight of (A-2) solid unend-capped resin.

[0039] The solid end-capping resin (A-1) that can be used in this invention has a unitary formula (I-1):

[0040] (R M 3SiO 1 / 2 ) a (SiO 4 / 2 ) b Z c

[0041] Each R M Each Z is independently a monovalent hydrocarbon group of 1 to 20 carbon atoms; each Z is independently a hydrolyzable group selected from the group consisting of alkoxy, hydroxyl, or mixtures thereof; c is 0 to a value sufficient to impart a hydrolyzable group content of up to 2% by weight based on the weight of the end-capping resin; and a and b have values ​​such that a > 4, b > 0, preferably b > 1, and the value of (a + b) is sufficient to impart a number-average molecular weight (Mn) of 500 g / mol to 8,000 g / mol to the end-capping resin, as measured by gel permeation chromatography (GPC) analysis. GPC analysis can be performed according to the test methods described in the Examples section below.

[0042] R M The hydrocarbon group can be selected from the group consisting of: alkyl groups, alkenyl groups, aryl groups, aralkyl groups, or mixtures thereof. (The last part, "R," appears to be a typographical error and is left untranslated.) MThe alkyl group typically has 1 to 20 carbon atoms, 1 to 15 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Examples of suitable alkyl groups include methyl, ethyl, propyl, pentyl, hexyl, and cyclohexyl. (The last part, "by R," appears to be a typo and can be left as is.) M The alkenyl group typically has 2 to 20 carbon atoms, 2 to 10 carbon atoms, 2 to 8 carbon atoms, or 2 to 6 carbon atoms. (The last part, "by R," appears to be a typographical error and is left untranslated.) M Examples of suitable alkenyl groups include vinyl, allyl, butenyl, and hexenyl. Preferably, the alkyl group is methyl, and the alkenyl group is vinyl. (By R) M The indicated aryl group may include cyclopentadienyl, phenyl, anthraceneyl, and naphthyl. Each R M It can be independently selected from methyl, vinyl, and phenyl. Preferably, at least one-third or at least two-thirds of R M The group is an alkyl group (e.g., a methyl group). For example, each R M An alkyl group, which is independently composed of 1 to 6 carbon atoms, preferably methyl.

[0043] The value of (a+b) in formula (I-1) is sufficient to impart 500 g / mol or greater, 1,000 g / mol or greater, 1,500 g / mol or greater, 2,000 g / mol or greater, 2,500 g / mol or greater, or even 2,700 g / mol or greater, and simultaneously 8,000 g / mol or less, 7,000 g / mol or less, 6,500 g / mol or less, 6,000 g / mol or less, 5,500 g / mol or less, 5,000 g / mol or less, or even 4,700 g / mol or less, as determined by GPC analysis. For example, the value of a can be 40 to 55 or 43 to 50. The value of b can be 45 to 65 or 50 to 57.

[0044] In formula (I-1), the value of c ranges from 0 to a value sufficient to impart a hydrolyzable group content of 0 to a maximum of 2% to the end-capping resin. The hydrolyzable group is typically a hydroxyl group. For example, a solid end-capping resin (A-1) contains 2% or less of silicon-bonded hydroxyl (OH) groups (also known as “silanol groups”) by weight based on the weight of the end-capping resin, such as 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, or even 1% or less of silicon-bonded hydroxyl groups. The weight percentage of silicon-bonded hydroxyl groups can be determined by nuclear magnetic resonance (NMR) spectroscopy. NMR analysis can be performed according to the test methods described in the Examples section below.

[0045] The solid uncapped resin (A-2) that can be used in this invention has a unitary formula (I-2):

[0046] (R M 3SiO 1 / 2 ) a’ (SiO 4 / 2 ) b’ Z c’

[0047] Each R M And Z as described above in the end-capping resin (A-1) section; c' has a value sufficient to impart to the uncapped resin a hydrolyzable group content of >2% to 10% by weight based on the weight of the uncapped resin, and a' and b' have values ​​such that a'>4, b'>0, preferably b'>1, and the value of (a'+b') is sufficient to impart to the uncapped resin 500 g / mol to 8000 g / mol of Mn, as measured by GPC analysis, for example, 1,000 g / mol or greater, 1,5 The concentrations of silicon-bonded OH groups may be 0.00 g / mol or greater, 2,000 g / mol or greater, 2,500 g / mol or greater, or even 2,700 g / mol or greater, and simultaneously 8,000 g / mol or less, 7,000 g / mol or less, 6,500 g / mol or less, 6,000 g / mol or less, 5,500 g / mol or less, 5,000 g / mol or less, or even 4,700 g / mol or less, as determined by GPC analysis. For example, the value of a' may be 40 to 55 or 43 to 50. The value of b' may be 45 to 65 or 50 to 57. The solid uncapped resin may contain >2%, >2.5%, or even >3% of silicon-bonded OH groups. The weight percentage of silicon-bonded OH groups can be determined by NMR spectroscopy. GPC and NMR analyses may be performed according to the test methods described in the Examples section below.

[0048] The solid polyorganosilicate resins that can be used in this invention (e.g., (A-1) and (A-2) above) contain the formula R M 3SiO 1 / 2 One functional unit (“M” unit) and SiO 4 / 2 The tetrafunctional silicate unit (“Q” unit). An example of the M unit could be (Me3SiO) 1 / 2 (Me2PhSiO) 1 / 2 ) or (Me2ViSiO 1 / 2 ), where Me represents methyl, Ph represents phenyl, and Vi represents vinyl. Polyorganosilicate resins may contain compounds having the formula (R MThe novel pentamer organopolysiloxanes (SiO)₄Si, which are byproducts of resin preparation, such as tetrakis(trimethylsiloxy)silane. The molar ratio of M units to Q units in polyorganosilicate resins (“M / Q ratio”) is typically in the range of 0.5 to 1.5, 0.65 to 1.3, or 0.8 to 1.2, as determined by NMR analysis. The M / Q ratio represents the total number of M units to the total number of Q units in the polyorganosilicate resin and includes contributions from any novel pentamers (if present). Polyorganosilicate resins may contain HOSiO 3 / 2 Unit (TOH unit) and / or HOR M 2SiO 1 / 2 This explains the content of silicon-bonded hydroxyl groups in polyorganosilicate resins.

[0049] Solid polyorganosilicate resins used in this invention (e.g., (A-1) and (A-2) above) can be prepared by any suitable method, such as co-hydrolysis of the corresponding silane or by a silica hydrosol end-capping method. Solid polyorganosilicate resins can be prepared by silica hydrosol end-capping methods, such as those disclosed in U.S. Patent 2,676,182 to Daudt et al.; U.S. Patent 4,611,042 to Rivers-Farrell et al.; and U.S. Patent 4,774,310 to Butler et al. The methods of Daudt et al. involve reacting a silica hydrosol under acidic conditions with a hydrolyzable triorganosilane (such as trimethylchlorosilane), a siloxane (such as hexamethyldisiloxane), or a mixture thereof, and recovering copolymers having monofunctional and tetrafunctional units. The resulting copolymers typically contain 2% to 5% by weight of hydroxyl groups. The silicon-bonded hydroxyl groups formed during the preparation of the polyorganosilicate resin can be converted into trialkylsiloxane groups or different hydrolyzable groups by reacting the organosilicon resin with a silane, disiloxane, or disilazane containing suitable end groups in a process called end-capping. The silane containing the hydrolyzable groups can be added in excess molar amounts required to react with the silicon-bonded hydroxyl groups on the polyorganosilicate resin. Solid polyorganosilicate resins can be prepared, for example, as described in U.S. Patent 8,017,712 to Berry et al. and references therein, and U.S. Patent 10,351,742 to Brown et al. and references therein, followed by the removal of volatile substances. Solid polysilicate resins (e.g., sheet resins) are also commercially available from a variety of sources, such as Dow Silicones Corporation, Midland, Michigan, USA; Momentive Performance Materials, Albany, New York, USA; and Bluestar Silicones USA Corp., East Brunswick, New Jersey, USA.

[0050] The starting material (A) can be a mixture of two or more solid polyorganosilicate resins with different structures, Mn, siloxane units, sequences, and / or OH content of silicon bonds. For example, the solid end-capped resin (A-1) can be present in an amount of 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or even 100% by weight, based on the weight of the starting material (A). The solid unend-capped resin (A-2) can be present in an amount of 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or even 0% by weight, based on the weight of the starting material (A). The solid polyorganosilicate resin component can be composed of the above-mentioned solid end-capped resin (A-1) and solid unend-capped resin (A-2), that is, the total concentration of (A-1) and (A-2) can be equal to 100% by weight based on the weight of the starting material (A).

[0051] The method for preparing the solvent-free PSA composition of the present invention further includes (ii) mixing the above-mentioned starting material (A) with starting material (B) and optionally starting material (C). The resulting mixture is further cooled to form an organosilicon-based portion (e.g., step (iii) of the method).

[0052] The starting material (B) that can be used in this invention is an aliphatic unsaturated polydiorganosiloxane (B-1), a branched polyorganosiloxane (B-2), or a mixture of (B-1) and (B-2).

[0053] The aliphatic unsaturated polydiorganosiloxane (B-1) that can be used in this invention comprises unit formula (II-1):

[0054] (R 1 2R 2 SiO 1 / 2 ) x (R 1 3SiO 1 / 2 ) y (R 1 R 2 SiO 2 / 2 ) z (R 1 2SiO 2 / 2 ) w ,

[0055] Each R 1 Independently, a monovalent hydrocarbon group of 1 to 20 carbon atoms without aliphatic unsaturated groups; each R 2Independently, it is a monovalent aliphatic unsaturated hydrocarbon group having 2 to 20 carbon atoms; x>0, y≥0, (x+y)=2, z≥0, w≥0, (w+z)>0, and the value of (x+y+z+w) is sufficient to impart 5,000 g / mol to 50,000 g / mol of Mn to aliphatic unsaturated polydiorganosiloxanes, as measured by GPC analysis. For example, the Mn of aliphatic unsaturated polydiorganosiloxane (B-1) can be 5,200 g / mol or greater, 5,500 g / mol or greater, 5,800 g / mol or greater, 6,000 g / mol or greater, 6,200 g / mol or greater, 6,500 g / mol or greater, or even 7,000 g / mol or greater, and simultaneously 48,000 g / mol or less, 45,000 g / mol or less, 40,000 g / mol or less, 35,000 g / mol or less, 30,000 g / mol or less, 25,000 g / mol or less, 20,000 g / mol or less, or even 18,000 g / mol or less. GPC analysis can be performed according to the test methods described in the Examples section below. The value of (w+z) can be 50 or higher, 100 or higher, 150 or higher, 200 or higher, or even 300 or higher, and at the same time 600 or lower, 500 or lower, 450 or lower, or even 400 or lower.

[0056] R 1 It typically has 1 to 20 carbon atoms, 1 to 15 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. R 1 Examples of suitable monovalent hydrocarbon groups include alkyl groups and aromatic groups, such as aryl groups and aralkyl groups, as described above. Each R 1 It can be an alkyl group with 1 to 6 carbon atoms independently. At least 50 mol%, 60 mol% or more, 70 mol% or more, or even 80 mol% or more of R 1 The monovalent hydrocarbon group represented can be methyl. The molar percentage of methyl groups in this article can be determined by NMR analysis. Preferably, each R 1 It is a methyl group.

[0057] R 2 It typically has 2 to 20 carbon atoms, 2 to 10 carbon atoms, 2 to 8 carbon atoms, or 2 to 6 carbon atoms. 2 The monovalent aliphatic unsaturated hydrocarbon group can be an alkenyl group. R 2Examples of suitable alkenyl groups include vinyl, allyl, propenyl (e.g., isopropenyl and / or n-propenyl); and butenyl, pentenyl, hexenyl, and heptenyl, as well as their branched and linear isomers; and cyclohexenyl. Preferably, the alkenyl group is vinyl. The alkenyl group in the aliphatic unsaturated polydiorganosiloxane may be located at a terminal position, a side-chain position, or both.

[0058] Examples of suitable aliphatic unsaturated polydiorganosiloxanes (B-1) include b1) dimethylvinylsiloxy-terminated polydimethylsiloxane, b2) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), b3) dimethylvinylsiloxy-terminated polymethylvinylsiloxane, b4) trimethylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), b5) trimethylsiloxy-terminated polymethylvinylsiloxane, b6) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), b7) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylphenylsiloxane), and b8) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / (b9) diphenylsiloxane, (b10) dimethylhexenylsiloxane, (b11) dimethylhexenylsiloxane, (b12) dimethylhexenylsiloxane, (b13) trimethylsiloxane, (b14) trimethylsiloxane, (b15) dimethylhexenylsiloxane, (b16) dimethylvinylsiloxane, or combinations thereof. Preferably, the aliphatic unsaturated polydiorganosiloxane (B-1) is selected from the group consisting of: b1) dimethylvinylsiloxy-terminated polydimethylsiloxane, b2) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), or a combination of b1) and b2). Aliphatic unsaturated polydiorganosiloxanes are known in the art and can be prepared by methods such as hydrolysis and condensation of corresponding organohalosilanes or equilibration of cyclic polydiorganosiloxanes.

[0059] The branched polyorganosiloxane (B-2) that can be used in this invention comprises unit formula (II-2):

[0060] (R 1 3SiO 1 / 2 ) g (R1 2R 2 SiO 1 / 2 ) h (R 1 2SiO 2 / 2 ) i (SiO 4 / 2 )

[0061] Where R 1 and R 2 As described above, and the values ​​of g, h, and i are such that 2 ≥ g ≥ 0, 4 ≥ h ≥ 0, 995 ≥ i ≥ 4, (g + h) = 4, and the value of (g + h + i) is sufficient to impart 5,000 g / mol to the branched polyorganosiloxanes as determined by GPC analysis. GPC analysis can be performed according to the test methods described in the Examples section below. For example, the Mn of branched polydiorganosiloxane (B-2) can be 5,200 g / mol or greater, 5,500 g / mol or greater, 5,800 g / mol or greater, 6,000 g / mol or greater, 6,200 g / mol or greater, 6,500 g / mol or greater, or even 7,000 g / mol or greater, and simultaneously 48,000 g / mol or less, 45,000 g / mol or less, 40,000 g / mol or less, 35,000 g / mol or less, 30,000 g / mol or less, 25,000 g / mol or less, 20,000 g / mol or less, or even 18,000 g / mol or less. The value of i can be 50 or higher, 100 or higher, 150 or higher, 200 or higher, or even 250 or higher, and simultaneously 600 or lower, 500 or lower, 400 or lower, or even 300 or lower. Methods for preparing branched polyorganosiloxanes (B-2) and examples of suitable branched polyorganosiloxanes (B-2) are disclosed, for example, in U.S. Patent No. 6,806,339 and U.S. Patent Publication 2007 / 0289495.

[0062] The starting material (B) can be a single aliphatic unsaturated polydiorganosiloxane (B-1); a mixture comprising two or more aliphatic unsaturated polydiorganosiloxanes that differ in at least one of the following properties: structure, Mn, siloxane unit and sequence; a single branched polyorganosiloxane (B-2); a mixture of two or more branched polyorganosiloxanes that differ in at least one of the following properties: structure, Mn, siloxane unit and sequence; or a mixture thereof. (B-1) and / or (B-2) can provide an amount of starting material (B) having a viscosity of 4,000 mPa·s or less, 3,500 mPa·s or less, 3,000 mPa·s or less, 2,500 mPa·s or less, 2,000 mPa·s or less, or even 1,500 mPa·s or less, as measured by a rotational viscometer, and simultaneously 200 mPa·s or greater, 300 mPa·s or greater, 400 mPa·s or greater, or even 500 mPa·s or greater. The viscosity can be determined according to the test methods described in the Examples section below.

[0063] The starting material (B) that can be used in this invention may be 46% or more, 47% or more, 48% or more, 49% or more, 50% or more, 51% or more, 52% or more, 53% or more, 54% or more, 55% or more, 60% or more, 62% or more, or even 65% or more, and simultaneously present in amounts of 90% or less, 85% or less, 80% or less, 75% or less, 74% or less, 73% or less, or even 70% or less. The total weight of the starting material in the solvent-free PSA composition may be the combined weight of starting materials (A) to (E) and starting materials (F) and (G), if present, as described below.

[0064] The starting material (C) that can be used in this invention is a polydiorganosiloxane resin having unit formula (III):

[0065] (R 1 2R G SiO 1 / 2 )2(R 1 2SiO 2 / 2 ) d

[0066] Where R 1 As mentioned above; each R GIndependently, it is a monovalent aliphatic unsaturated hydrocarbon group, hydroxyl group, or combination thereof having 2 to 20 carbon atoms; and d has a value sufficient to impart Mn to the polydiorganosiloxane resin of 300,000 g / mol or greater, such as 350,000 g / mol or greater, 400,000 g / mol or greater, 450,000 g / mol or greater, 500,000 g / mol or greater, and simultaneously 1,000,000 g / mol or less, 900,000 g / mol or less, 800,000 g / mol or less, 700,000 g / mol or less, or even 600,000 g / mol or less, as measured by GPC analysis. GPC analysis can be performed according to the test methods described in the Examples section below. For example, the value of d can be 4,000 or higher, 4,500 or higher, 5,000 or higher, 5,500 or higher, or even 6,000 or higher, and at the same time 10,000 or lower, 9,000 or lower, 8,000 or lower, or even 7,000 or lower.

[0067] R 1 As described above in the section on starting material (B). From R G The aliphatic unsaturated hydrocarbon group typically has 2 to 20 carbon atoms, 2 to 10 carbon atoms, 2 to 8 carbon atoms, or 2 to 6 carbon atoms. The aliphatic unsaturated hydrocarbon group can be alkenyl. (The last part, "R," appears to be a typographical error and is left untranslated.) G Examples of suitable alkenyl groups include vinyl, allyl, propenyl (e.g., isopropenyl and / or n-propenyl); and butenyl, pentenyl, hexenyl, and heptenyl, as well as their branched and linear isomers; and cyclohexenyl. Preferably, the alkenyl group is vinyl. The alkenyl and / or hydroxyl groups in the polydiorganosiloxane resin may be located at terminal positions. The starting material (C) may be a mixture of two or more different polydiorganosiloxane resins.

[0068] Examples of suitable polydiorganosiloxane resins include C1) dimethylvinylsiloxy-terminated polydimethylsiloxane, C2) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylphenyl)siloxane, C3) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / diphenyl)siloxane, C4) phenyl, methyl, vinyl-siloxy-terminated polydimethylsiloxane, and C5) dimethylhexenylsiloxy-terminated polydimethylsiloxane. C6) dimethylhexenyl-siloxy-terminated poly(dimethylsiloxane / methylphenyl)siloxane, C7) dimethylhexenyl-siloxy-terminated poly(dimethylsiloxane / diphenyl)siloxane, C8) hydroxyl-terminated poly(dimethylsiloxane / methylphenyl)siloxane, C9) hydroxyl-terminated poly(dimethylsiloxane / diphenyl)siloxane, C10) hydroxyl-terminated poly(dimethylsiloxane / diphenyl)siloxane, or mixtures thereof.

[0069] The starting material (C) that can be used in this invention may be 0 or more, 0.1% or more, 0.2% or more, 0.5% or more, 0.8% or more, 1% or more, 1.5% or more, or even 2% or more by weight, based on the total weight of all starting materials in the solvent-free PSA composition, and simultaneously present in amounts of 6% or less, 5.5% or less, 5% or less, 4% or less, 2.3% or less, 2% or less, or even 1.6% or less.

[0070] The starting substances (A), (B) and (C) are provided in amounts in the range of 0.1 to 1.2, 0.15 to 1.1, 0.2 to 1.0, 0.25 to 0.9, or 0.3 to 0.8, where the weight ratio of (A):[(B)+(C)] is (i.e., the amount of starting substance (A) is equal to the combined amount of starting substances (B) and (C), referred to as the R / P ratio).

[0071] The method for preparing the solvent-free PSA composition of the present invention further includes (iv) blending the organosilicon-based portion obtained above with other starting materials including starting materials (D) and (E) and optionally starting materials (F) and / or (G) to form a solvent-free PSA composition.

[0072] The starting material (D) used in this invention is one or more polyorganohydrosiloxanes. The starting material (D) acts as a crosslinking agent in the hydrosilylation reaction of the solvent-free PSA composition. Polyorganohydrosiloxanes typically have at least two or at least three silicon-bonded hydrogen atoms per molecule. Polyorganohydrosiloxanes may comprise unit formula (IV):

[0073] (R 1 3SiO 1 / 2 )2(R 1 2SiO 2 / 2) e (HR 1 2SiO 2 / 2 ) f

[0074] Where R 1 As mentioned above, e≥0, f≥3, and (e+f) is 4 to 500.

[0075] R 1 As described in section (B) above regarding starting materials. Preferably, each R 1 Alkyl groups having 1 to 6 carbon atoms independently, more preferably methyl groups. The value of (e+f) can be 4 or higher, 5 or higher, 7 or higher, 10 or higher, 20 or higher, 30 or higher, 40 or higher, or even 50 or higher, and simultaneously 500 or lower, 400 or lower, 200 or lower, 150 or lower, 140 or lower, 130 or lower, 120 or lower, 110 or lower, or even 100 or lower.

[0076] The polyorganohydrosiloxanes used in this invention may comprise, based on the weight of the polyorganohydrosiloxane, 0.38% or more, 0.5% or more, 0.6% or more, or even 0.75% or more, and simultaneously 2% or less, 1.9% or less, 1.8% or less, 1.75% or less, 1.7% or less, or even 1.6% or less, of silicon-bonded hydrogen atoms. The content of silicon-bonded hydrogen atoms can be determined by NMR analysis.

[0077] Methods for preparing polyorganohydrosiloxanes (such as the hydrolysis and condensation of organohydrohalosilanes) are well known in the art. Examples of suitable polyorganohydrosiloxanes include D1) trimethylsiloxy-terminated poly(dimethyl / methylhydro)siloxanes, D2) trimethylsiloxy-terminated polymethylhydrosiloxanes, D3) dimethylhydrosiloxy-terminated polydimethylsiloxanes, D4) dimethylhydrosiloxy-terminated poly(dimethylsiloxane / methylhydrosiloxanes, D5) dimethylhydrosiloxy-terminated polymethylhydrosiloxanes, or combinations thereof.

[0078] The starting material (B) is present in an amount sufficient to provide a molar ratio (referred to as the SiH / Vi ratio) of silicon-bonded hydrogen atoms to aliphatic unsaturated hydrocarbon groups in all starting materials containing aliphatic unsaturated hydrocarbon groups in a solvent-free PSA composition of 1 to 10, 1.1 to 8, 1.2 to 7, 1.3 to 6, 1.4 to 5, or 1.5 to 4. Typically, the starting material (B) is present in an amount of 0.1% or more, 1% or more, or even 2% or more by weight, based on the total weight of the starting materials containing aliphatic unsaturated hydrocarbon groups in the solvent-free PSA composition, and simultaneously in an amount of 5% or less, 4% or less, or even 3% or less.

[0079] The starting material (E) that can be used in this invention is a hydrosilylation catalyst. The hydrosilylation catalyst can promote the addition reaction between the starting material (B) and the starting material (D). The hydrosilylation catalyst may include a platinum group metal catalyst. Such hydrosilylation catalysts may include (E1) metals selected from platinum, rhodium, ruthenium, palladium, osmium, and iridium, preferably platinum; (E2) compounds of such metals, including, for example, triphenylphosphine-rhodium(I) (Wilkinson's Catalyst), diphosphine-rhodium chelates such as [1,2-bis(diphenylphosphine)ethane]dichloro-rhodium or [1,2-bis(diethylphosphine)ethane]dichloro-rhodium, chloroplatinic acid (Speier's Catalyst), chloroplatinic acid hexahydrate, or platinum dichloride; (E3) complexes of platinum group metal compounds with low molecular weight organopolysiloxanes; (E4) platinum group metal compounds or combinations thereof microencapsulated in a matrix or core-shell structure; and (E5) complexes or combinations thereof microencapsulated in a resin matrix. Complexes of platinum with low molecular weight organopolysiloxanes include complexes of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum (Karstedt catalysts). Exemplary hydrosilylation catalysts are described in U.S. Patents 3,159,601 and 3,220,972.

[0080] The concentration of the hydrosilylation catalyst is sufficient to catalyze the hydrosilylation reaction between silicon-bonded hydrogen atoms and aliphatic unsaturated groups in a solvent-free PSA composition. Typically, the concentration of the hydrosilylation catalyst is sufficient to provide, based on the total weight of the starting materials in the solvent-free PSA composition, 1 or more parts per million (ppm), 5 ppm or more, 10 ppm or more, 20 ppm or more, or even 30 ppm or more, while simultaneously providing 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 100 ppm or less, or even 50 ppm or less of platinum group metals.

[0081] The starting material (F) that can be used in this invention is a hydrosilylation reaction inhibitor, which can optionally be used to change the reaction rate of silicon-bonded hydrogen atoms and aliphatic unsaturated groups in a solvent-free PSA composition (compared to the reaction rate of the same starting material but without the inhibitor). Examples of suitable inhibitors of hydrosilylation reactions include alkynols, such as methylbutynol, etynylcyclohexanol, 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-octyyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-etynyl-1-cyclohexanol (ETCH), and combinations thereof; cycloalkenylsiloxanes, such as methylvinylcyclosiloxanes, examples of which include 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1 3,5,7-Tetrahexenylcyclotetrasiloxanes and combinations thereof; alkenylene compounds, such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne and combinations thereof; triazoles, such as benzotriazoles; phosphines; thiols; hydrazides; amines, such as tetramethylethylenediamine, 3-dimethylamino-1-propyne, n-methylpropynylamine, propynylamine and 1-ethynylcyclohexylamine; dialkyl esters of fumarate, such as diethyl fumarate, dienyl fumarate, diallyl fumarate, dialkoxyalkyl fumarate, maleic esters, such as diallyl maleate and diethyl maleate; nitriles; ethers; carbon monoxide; alkenes, such as cyclooctadiene, divinyltetramethyldisiloxane; alcohols, such as benzyl alcohol; or mixtures thereof.

[0082] The hydrosilylation reaction inhibitors that can be used in this invention can be 0 or more, 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, or even 1% or more by weight, based on the total weight of the starting material in the solvent-free PSA composition, and simultaneously present in amounts of 5% or less, 4% or less, 3% or less, or even 2% or less.

[0083] The starting material (G) that can be used in this invention is a fixation additive. The fixation additive may include reaction products of alkoxysilanes, vinylacetoxysilanes and epoxy-functional alkoxysilanes, alkoxysilanes and polyorganosiloxanes having at least one aliphatic unsaturated hydrocarbon group and at least one hydrolyzable group per molecule, and blends and / or reaction products of epoxy-functional alkoxysilanes (e.g., blends and / or reaction products of hydroxyl-terminated vinyl-functional polydimethylsiloxanes with glycidyl etheroxypropyltrimethoxysilane), or mixtures thereof. Alkoxysilanes can be unsaturated or epoxy-functionalized alkoxysilanes, methyltrimethoxysilanes, 3-methacryloyloxypropyltrimethoxysilanes, 3-aminopropyltrimethoxysilanes, N-(2-aminoethyl)-3-aminopropyltrimethoxysilanes, bis(trimethoxysilyl)propane and bis(trimethoxysilyl)hexane; tetramethoxysilanes, tetraethoxysilanes, dimethyldimethoxysilanes, methylphenyldimethoxysilanes, methylphenyldiethoxysilanes, phenyltrimethoxysilanes, methyltrimethoxysilanes, methyltrimethoxysilanes, or mixtures thereof. Examples of suitable epoxy-functionalized alkoxysilanes include 3-epoxypropoxypropyltrimethoxysilanes, 3-epoxypropoxypropyltriethoxysilanes, (epoxycyclohexyl)ethyldimethoxysilanes, (epoxycyclohexyl)ethyldiethoxysilanes, or mixtures thereof. Examples of suitable unsaturated alkoxysilanes include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hexenyltrimethoxysilane, undecenyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, or mixtures thereof. Suitable commercially available fixative additives may include, for example, SYL-OFF. TM 297. SYL-OFF TM 397 and SYL-OFF TM SL 9250, all of them are available from Dow Silicones, Inc. in Midland, Michigan, USA (SYL-OFF is a trademark of Dow Silicones).

[0084] Specifically, examples of immobilizing additives include (G1) vinyltriacetoxysilane, (G2) glycidyl etheroxypropyltrimethoxysilane, (G3) blends or reaction products of (G1) and (G2), and (G4) blends or reaction products of (G3) and polydimethylsiloxanes capped with hydroxyl groups, methoxy groups, or both hydroxyl groups and methoxy groups.

[0085] The fixation additives that can be used in this invention may be present in amounts of 0 or more, 0.01% or more, 0.05% or more, 0.1% or more, or even 0.5% or more by weight, based on the total weight of the starting material in the solvent-free PSA composition, and simultaneously in amounts of 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, or even 1% or less.

[0086] A method for preparing the solvent-free PSA composition of the present invention includes (i) providing a starting material (A), a starting material (B), and optionally one or more other additional starting materials such as a starting material (C), and (ii) mixing the starting materials (A) and (B), and optionally the starting material (C), at a temperature of 100°C or higher, such as 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, or even 150°C or higher, and simultaneously at a temperature of 230°C or lower, 220°C or lower, 210°C or lower, 200°C or lower, 190°C or lower, or even 180°C or lower. When mixed with the starting material (B) and optionally the starting material (C), the solid polyorganosilicate resin used for the starting material (A) (e.g., (A-1) and (A-2)) may be in flake or powder form. The mixing temperature in step (ii) may be selected to form a homogeneous mixture that is generally clear to the naked eye. The term "homogeneous mixture" as used herein refers to a mixture that does not exhibit phase separation or stratification when observed with the naked eye. The mixing of starting materials can be achieved through any technique known in the art, such as milling, blending, extrusion, and stirring, in a batch or continuous process. The duration of mixing the aforementioned starting materials may depend on the molecular weight and concentration of the starting materials (A) and (B), and / or the mixing method, for example, 10 minutes to 4 hours, 0.5 hours to 2 hours, or 1 hour to 2 hours.

[0087] The method for preparing the solvent-free PSA composition of the present invention further includes (iii) cooling the resulting mixture obtained in step (ii) to form a silicone-based portion. The cooling temperature can be 60°C or lower, 50°C or lower, 40°C or lower, 30°C or lower, or even 25°C or lower. The silicone-based portion is liquid at room temperature and is typically a homogeneous mixture. When measured by a rotational viscometer, the silicone-based portion has a viscosity of less than 5,000 mPa·s at room temperature, for example, 4,950 mPa·s or less, 4,900 mPa·s or less, 4,800 mPa·s or less, 4,500 mPa·s or less, 4,000 mPa·s or less, 3,500 mPa·s or less, 3,000 mPa·s or less, 2,500 mPa·s or less, or even 2,000 mPa·s or less. The viscosity can be determined according to the test methods described in the Examples section below.

[0088] The method for preparing the PSA composition of the present invention further includes (iv) blending the silicone-based portion obtained in step (iii) with starting materials (D) a hydrosilylation catalyst and (E) a polyorganohydrosiloxane, and optionally other additional starting materials including a hydrosilylation inhibitor and / or a fixation additive. When present, the hydrosilylation inhibitor may be added to the silicone-based portion prior to the hydrosilylation catalyst, for example, when the solvent-free PSA composition is to be prepared as a single-component composition. The method for preparing the solvent-free PSA composition can be used to prepare a multi-component composition comprising at least the silicone-based portion and a curing agent portion obtained from step (iii) of the above method. The curing agent portion may be prepared by incorporating starting materials comprising at least the hydrosilylation catalyst, the polyorganohydrosiloxane, and optionally the other additional starting materials described above. The hydrosilylation inhibitor may be included in one or more of the silicone-based portion, the curing agent portion, or a separate additional portion. The fixation additive may be added to the silicone-based portion and / or the curing agent portion, or may be added as a separate additional portion. Combine the components of the solvent-free PSA composition just before use. When using a two-part composition, the weight ratio of the base component to the curing agent component can be in the range of 1:1 to 10:1.

[0089] The method for preparing the solvent-free PSA composition of the present invention can be carried out in the absence of a substantially solvent-free environment, i.e., without the intentional addition of solvent during the preparation of the solvent-free PSA composition. For example, the method of the present invention does not require the addition of solvent to dissolve one or more starting materials (such as solid polysilicate resin components) in the solvent-free PSA composition and / or the addition of solvent to the silicone-based portion. “Substantially solvent-free” means a solvent content of 100 ppm or less, 80 ppm or less, 50 ppm or less, or even 0 ppm by weight, based on the total weight of the starting materials in the solvent-free PSA composition. The solvent content can be measured by gas chromatography (GC). “Solvent” as used herein refers to any compound capable of dissolving the solid polysilicate resin component (starting material (A)), i.e., the polysilicate resin component is soluble in a solvent. The solvent may be an organic solvent, such as saturated or unsaturated aliphatic or aromatic hydrocarbons, such as benzene, toluene, xylene, hexane, heptane, octane, isoalkanes, hydrocarbon compounds having 8 to 18 carbon atoms per molecule and at least one aliphatic unsaturated group, such as tetradecene; ketones, such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; acetates, such as ethyl acetate or isobutyl acetate; ethers, such as glycol ethers, such as propylene glycol methyl ether, dipropylene glycol methyl ether and propylene glycol n-butyl ether, diisopropyl ether, or 1,4-dioxane; cyclic siloxanes having an average degree of polymerization of 3 to 10, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and / or decamethylcyclopentasiloxane; or mixtures thereof.

[0090] Because there is essentially no solvent, the method for preparing solvent-free PSA compositions does not involve (i.e., does not contain) additional stripping procedures for solvent removal, such as stripping to remove solvent. The method of the present invention enables the preparation of solvent-free PSA compositions without the aid of solvents, while still providing a resulting solvent-free PSA composition having the desired low viscosity as described below. The PSA compositions prepared by the method of the present invention are solvent-free. The solvent-free PSA compositions contain no solvent or may contain trace amounts of residual solvent resulting from the delivery of the starting material in the PSA composition, for example, less than 100 ppm of solvent by weight based on the total weight of the solvent-free PSA composition (e.g., based on the total weight of the starting material in the solvent-free PSA composition). The amount of residual solvent in the solvent-free PSA composition can be measured by gas chromatography (GC). The solvent-free PSA compositions prepared by the method of the present invention can provide low viscosity, making them suitable for direct coating onto a substrate without the need to add solvent to the solvent-free PSA composition prior to use. For example, solvent-free PSA compositions typically have a viscosity of less than 5,000 mPa·s at room temperature when measured with a rotational viscometer within 0.5 hours of mixing all the starting materials of the PSA composition together; for example, 4,950 mPa·s or less, 4,900 mPa·s or less, 4,800 mPa·s or less, 4,500 mPa·s or less, 4,000 mPa·s or less, 3,500 mPa·s or less, 3,000 mPa·s or less, 2,500 mPa·s or less, or even 2,000 mPa·s or less. The viscosity can be determined according to the test methods described in the Examples section below.

[0091] This invention also relates to a pressure-sensitive adhesive comprising a cured product of a solvent-free PSA composition, i.e., a pressure-sensitive adhesive formed by curing a solvent-free PSA composition via a hydrosilylation reaction. Adhesive articles (such as films or strips) can be prepared by applying a solvent-free PSA composition to a substrate. This invention also relates to a method for preparing adhesive articles such as protective films, the method comprising: applying a solvent-free PSA composition to a substrate, and curing the solvent-free PSA composition. The application of the solvent-free PSA composition to the substrate can be performed in various ways, including, for example, dispensing, spin coating, film coating, spraying, jetting, dipping, casting, screen printing, or by using brushes, rollers, or coating bars, such as gravure coating machines, comma coating machines, offset coating machines, offset gravure coating machines, roller coating machines, reverse roller coating machines, air knife coating machines, or curtain coating machines. The substrate can be any material capable of withstanding the curing conditions described below for curing the solvent-free PSA composition to form a PSA on the substrate. Suitable substrates may include, for example, polymer films such as polyimide (PI), polyetheretherketone (PEEK), polyethylene naphthalate (PEN), liquid crystal polyaramid, polyamide-imide (PAI), polyether sulfide (PES), polyethylene terephthalate (PET), polycarbonate (PC), thermoplastic polyurethane (TPU), polyethylene (PE), or polypropylene (PP); glass cloth, aluminum foil, titanium, copper foil, nickel, silver, or gold. The substrate may be a PET or PI film.

[0092] The method of preparing the adhesive article may optionally include treating the substrate prior to the application of the solvent-free PSA composition. The substrate treatment may be carried out by any convenient means, such as applying a primer, or subjecting the substrate to corona discharge treatment, etching, or plasma treatment before the solvent-free PSA composition is applied to the substrate.

[0093] Since no solvent is present in the method for preparing the solvent-free PSA composition of the present invention, the method for preparing the adhesive article does not include (i.e., does not include) steps such as removing the solvent before and / or during curing the solvent-free PSA composition. Curing of the solvent-free PSA composition can be carried out at high temperatures up to 200°C (e.g., 80°C to 200°C, 100°C to 160°C, or 110°C to 150°C) for a time sufficient to cure the solvent-free PSA composition, for example, 30 seconds to 1 hour or 1 minute to 5 minutes. This forms a pressure-sensitive adhesive on the substrate. The amount of solvent-free PSA composition to be applied to the substrate depends on the specific application; however, this amount is sufficient to ensure that (after curing) the film thickness of the pressure-sensitive adhesive can be 5 micrometers (μm) to 100 μm, 6 μm to 50 μm, 8 μm to 40 μm, or 10 μm to 30 μm.

[0094] The method of preparing the adhesive article of the present invention may optionally include applying a removable release liner to the PSA opposite to the substrate, such that the PSA is located between the substrate and the release liner. The release liner may be applied before, during, or after curing the solvent-free PSA composition.

[0095] The adhesive articles prepared as described above can be used in electronic applications such as display devices. The solvent-free PSA composition of the present invention can be cured to form a PSA on glass or stainless steel with a peel bond strength of 20 g / in (7.87 g / cm) or less, for example, 0.5 g / in to 20 g / in, 1 g / in to 15 g / in, or 3 g / in to 10 g / in. The low adhesion properties of the PSA to glass and stainless steel prepared from the solvent-free PSA composition make the protective film suitable for surface protection of electronic devices, such as screen or other surface protection during shipment of devices (such as smartphones or tablets), or for screen protection of such devices at the end-user location. The adhesive article can be a protective film that can be used to protect display glass.

[0096] Example

[0097] Some embodiments of the invention will now be described in the following examples, wherein all parts and percentages are by weight unless otherwise stated.

[0098] Except for ETCH (available from BASF) and tetradecene (available from BP), all the following materials listed in Table 1 are available from Dow Silicones.

[0099] Table 1

[0100]

[0101]

[0102] *Viscosity was measured according to the test methods described below. Mn was measured by GPC as described below. The OH content and vinyl content of silicon bonds (in weight %) were determined by NMR analysis as described below. M represents (CH3)3SiO 1 / 2 -,D represents (CH3)2SiO 2 / 2 -,D' represents (CH3)2HSiO 2 / 2 -, Q represents SiO 4 / 2 -, M Vi It represents (CH3)2(CH2=CH)-SiO 1 / 2 -and D Vi It represents (CH3)(CH2=CH)-SiO 2 / 2 -

[0103] The following standard analytical equipment and methods are used to illustrate and determine the properties and characteristics described herein:

[0104] NMR analysis

[0105] Using the reference embodiment 2 described in column 32 of U.S. Patent 9,593,209. 29 Si NMR technology measures the weight percentage of silicon-bonded hydroxyl groups, the molar percentage of methyl groups, the amount of M units relative to Q units, the content of silicon-bonded hydrogen atoms, and the vinyl content.

[0106] Gel permeation chromatography (GPC) analysis

[0107] The number-average molecular weight (Mn) of the starting material (A) was determined using GPC analysis as follows. The sample was diluted in HPLC-grade ethyl acetate (~10 mg / mL), filtered through a 0.45 μm PTFE filter, and analyzed by GPC. The injection volume of the sample was 100 μL. The columns used in this analysis consisted of a PLgel Mixed D column, a PLgel Mixed E column, and a guard column. The columns and all detectors were heated to 35°C. ASTM-certified polystyrene with a weight-average molecular weight (Mw) of 113,500 was used for instrument calibration (100 μL injection). A Viscotek TDA-305 triple detector array was used in conjunction with a Viscotek GPCmax autosampler for data collection. Data acquisition was performed using Omni Sec version 4.6.

[0108] Mn in starting materials (B) and (C) was determined using GPC analysis. The chromatographic apparatus consisted of a Waters 2695 separation module equipped with a vacuum degasser and a Waters 2414 refractive index detector. Three Styragel... TM HR column (300 mm × 7.8 mm) (molecular weight separation range 100 to 4,000,000), followed by Styragel. TMSeparation was performed using a guard column (30 mm × 4.6 mm), Styragel, a trademark of Waters Technologies Corporation. Analysis was performed using certified-grade tetrahydrofuran (THF) flowing at 1.0 mL / min as the eluent, with both the column and detector heated to 35°C. A 1.0% weight / volume (wt. / v) sample was prepared by weighing 0.050 g into an 8 mL glass vial and diluting with 5 mL of THF. After filtration through a 0.45 μm PTFE filter, the sample solution was transferred to a glass autosampler vial. A 100 μL injection volume was used, and data were collected over 37 min. Data collection was performed using Waters Empower GPC software. Data analysis was performed using Agilent Cirrus software. The molecular weight average was determined relative to a calibration curve (3rd order) created using polystyrene standards covering a molecular weight range of 474–1,270,000.

[0109] Adhesion test

[0110] At least 50 grams of the silicone PSA composition sample were applied to a polyethylene terephthalate (PET) film using a four-bird bar, and then cured in an oven at 140°C for 2 minutes. After curing, the coating thickness of the resulting PSA was measured using a micrometer and is given in Table 2. The resulting film with the silicone PSA was cooled and cut into strips one inch wide.

[0111] These strip samples were laminated onto a clean substrate using a 2 kg roller, pressing back and forth twice to ensure contact between the silicone PSA and the substrate, and then held at 25°C for 24 hours prior to testing. The substrate was either stainless steel (SS) or glass. The adhesion of each strip sample to the substrate was then tested by peeling each strip from the substrate at a 180° angle and a speed of 12 inches / minute (0.3 m / min) on a TMI Release and Adhesion Tester. Adhesion strength on the substrate is reported in g / in. The results are given in Table 2.

[0112] Viscosity

[0113] Viscosity was measured at room temperature (23±2℃) using a rotational viscometer (Brookfield RVDV-I+PRO viscometer) with rotor #6 at a speed of 10 revolutions per minute (rpm).

[0114] Gas chromatography (GC)

[0115] Residual solvent was determined using GC. The sample (0.05 g) was added to a 2 mL vial and then treated with 1 mL of hexane to form a hexane solution (using 10 μL of dodecane as an internal standard). The hexane solution was analyzed using flame ionization detection (FIR) with GC. The experimental relative response factor (RRF = 0.934 for xylene) was calculated. The GC instrument conditions and parameters used are as follows:

[0116] GC instrument: Agilent 6890N; Oven: 40℃ (3 min) to 310℃ (35 min), 15℃ / min; Inlet: 280℃, 18.5 psi, split 20:1; Column: DB-5MS UI, 30 m × 0.25 mm × 0.25 μm; Detector: FID, Temperature: 300℃, H2 flow rate: 40.0 mL / min, Air flow rate: 450.0 mL / min, Makeup flow rate: 45 mL / min; and Injection volume: 1.0 μL.

[0117] Examples (Ex) 1-8

[0118] Based on the formulations given in Table 2, solid resin and vinyl polymer (and / or gum, if present) were added to a flask equipped with a stirrer and mixed under stirring. The contents of the flask were heated and maintained at 150°C for 2 hours with stirring, resulting in a clear, homogeneous mixture. The mixture in the flask was then cooled to room temperature to form a homogeneous liquid silicone-based fraction. The viscosity of the silicone-based fraction was measured according to the test methods described above, and the results are given in Table 2.

[0119] The ETCH inhibitor was then added to the base material and mixed for 5 minutes. The crosslinking agent, catalyst, and fixative additive were then added sequentially, with each starting material mixed for at least 1 minute before adding the next. The adhesive properties of the resulting silicone PSA composition were evaluated according to the adhesive strength test method described above.

[0120] As shown in Table 2, the base portion of all solvent-free PSA compositions of Examples 1-8 exhibits a viscosity of less than 5,000 mPa·s. The base portion of Example 1 has <0.2 ppm of residual solvent, as measured by the GC assay described above. The solvent-free PSA compositions of Examples 1-8 were directly coated onto a PET film and cured to form a PSA with an adhesion of ≤20 g / in on stainless steel or glass, suitable for protective film applications.

[0121] Table 2. Formulation and properties of solvent-free PSA compositions

[0122]

[0123] * Visually inspect the appearance of the PSA film (i.e., the coating appearance). If the surface of the PSA film is smooth and does not show any fire pits, the film appearance is defined as "good". Conversely, if fire pits are observed on the surface of the PSA film, the film appearance is defined as "unacceptable".

[0124] The R / P ratio is calculated by dividing the total weight of the solid resins by the total weight of the gum and vinyl polymers.

[0125] The SiH / Vi ratio is calculated by dividing the amount of silicon-bonded hydrogen atoms from the crosslinking agent by the combined amount of vinyl groups from the starting material (including vinyl polymers and gums).

[0126] Compare examples A and B.

[0127] Following the procedure described in Example 1, the base material portions of Comparative Examples A and B were prepared based on the formulations given in Table 3. Then, the inhibitors, crosslinking agents, catalysts, and fixative additives given in Table 3 were sequentially added to the obtained base material portions. The resulting mixtures of Comparative Examples A and B both gelled.

[0128] Table 3. Formulations of comparative organosilicon PSA compositions

[0129]

[0130] *The R / P ratio is calculated by dividing the total weight of the solid resin by the total weight of the gum and vinyl polymer.

[0131] The SiH / Vi ratio is calculated by dividing the amount of silicon-bonded hydrogen atoms from the crosslinking agent by the combined amount of vinyl groups from the vinyl polymer and the resin.

Claims

1. A method for preparing a solvent-free pressure-sensitive adhesive composition, the method comprising: (i) Providing a starting material (A) of a solid polyorganosilicate resin component, comprising: (A-1) A solid end-capping resin having a unitary formula (I-1) at a weight of 90% to 100% based on the starting material (A): (R M 3SiO 1 / 2 ) a (SiO 4 / 2 ) b Z c Each R M Each Z is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms; each Z is independently a hydrolyzable group selected from the group consisting of alkoxy, hydroxyl, or mixtures thereof; c The value is 0 to a value sufficient to impart to the end-capping resin a hydrolyzable group content of up to 2% by weight based on the weight of the end-capping resin; and a and b The value it has makes a > 4. b >0, and ( a + b The value of ) is sufficient to impart a number-average molecular weight of 500 g / mol to the end-capping resin from 8,000 g / mol; as well as (A-2) 0 to 10% by weight of a solid uncapped resin having a unit formula (I-2) based on the starting material (A): (R M 3SiO 1 / 2 ) a’ (SiO 4 / 2 ) b’ Z c’ Where R M And Z as described above; a’ and b’ The value it has makes a’ > 4. b’ > 0, and ( a’ + b’ The value of ) is sufficient to give the uncapped resin a number-average molecular weight of 500 g / mol to 8,000 g / mol; and c’ It has a value sufficient to impart a hydrolyzable group content of >2% to 10% by weight based on the weight of the uncapped resin; (ii) Mix the starting material (A) with the starting material (B) and the starting material (C) at a temperature of 100°C or higher; The starting material (B) is an aliphatic unsaturated polydiorganosiloxane (B-1), a branched polyorganosiloxane (B-2), or a mixture of (B-1) and (B-2). The aliphatic unsaturated polydiorganosiloxane (B-1) comprises unit formula (II-1): (R 1 2R 2 SiO 1 / 2 ) x (R 1 3SiO 1 / 2 ) y (R 1 R 2 SiO 2 / 2 ) z (R 1 2SiO 2 / 2 ) w Each R 1 Independently, a monovalent hydrocarbon group having 1 to 20 carbon atoms that does not contain aliphatic unsaturated groups; each R 2 Independently, it is a monovalent aliphatic unsaturated hydrocarbon group having 2 to 20 carbon atoms; x , y , z and w The value it has makes x > 0、 y ≥ 0、( x + y ) = 2、 z ≥ 0、 w ≥ 0, ( w + z ) > 0, and ( x + y + z + w The value of ) is sufficient to give the aliphatic unsaturated polydiorganosiloxane a number-average molecular weight of 5,000 g / mol to 50,000 g / mol; The branched polyorganosiloxane (B-2) comprises unit formula (II-2): (R 1 3SiO 1 / 2 ) g (R 1 2R 2 SiO 1 / 2 ) h (R 1 2SiO 2 / 2 ) i (SiO 4 / 2 ) Where R 1 and R 2 As mentioned above, and g , h and i The value that makes 2≥ g ≥0, 4≥ h >0, 995≥ i ≥4、( g + h ) = 4, and ( g + h + i The value of ) is sufficient to give the branched polyorganosiloxane a number-average molecular weight of 5,000 g / mol to 50,000 g / mol; The starting material (C) is a polydiorganosiloxane resin with unit formula (III): (R 1 2R G SiO 1 / 2 )2(R 1 2SiO 2 / 2 ) d Where R 1 As mentioned above; each R G Independently, it is a monovalent aliphatic unsaturated hydrocarbon group having 2 to 20 carbon atoms; and d It has a number-average molecular weight value sufficient to impart a molecular weight of 300,000 g / mol or greater to the polydiorganosiloxane resin; The starting materials (A), (B), and (C) are provided in an amount that is 0.3 to 0.8 of the weight ratio of the amount of starting material (A) to the combined amount of starting material (B) and starting material (C), wherein the amount of starting material (B) is 50% to 80% by weight based on the total weight of the starting materials in the solvent-free pressure-sensitive adhesive composition, and the amount of starting material (C) is 1% to 6% by weight based on the total weight of the starting materials in the solvent-free pressure-sensitive adhesive composition. (iii) Cooling the mixture obtained in step (ii) to form an organosilicon-based portion having a viscosity of less than 5,000 mPa·s at room temperature; and (iv) The organosilicon-based material obtained in step (iii) is blended with starting material (D) polyorganohydrosiloxane, starting material (E) hydrosilylation catalyst, optional starting material (F) hydrosilylation inhibitor, and optional starting material (G) fixation additive; thereby forming the solvent-free pressure-sensitive adhesive composition. The method is carried out using a solvent of 100 ppm or less by weight, based on the total weight of the starting materials in the solvent-free pressure-sensitive adhesive composition.

2. The method of claim 1, wherein each R 1 Independently an alkyl group having 1 to 6 carbon atoms and each R 2 Independently, it is an alkenyl group having 2 to 6 carbon atoms.

3. The method according to claim 1, wherein the aliphatic unsaturated polydiorganosiloxane (B-1) and the branched polyorganosiloxane (B-2) each independently have a number-average molecular weight of 5,500 g / mol to 20,000 g / mol.

4. The method according to claim 1, wherein the mixing in step (ii) is carried out at a temperature of 120°C to 230°C.

5. The method according to claim 1, wherein the starting material (B) has a viscosity of 3,000 mPa·s or less at room temperature.

6. The method of claim 1, wherein each R M Independently, it is an alkyl group having 1 to 6 carbon atoms.

7. The method of claim 1, wherein the starting material is present in an amount provided as a molar ratio of silicon-bonded hydrogen atoms to aliphatic unsaturated groups in the solvent-free pressure-sensitive adhesive composition of 1 to 10.

8. The method according to claim 1, wherein the weight ratio of the amount of starting material (A) to the combined amount of starting material (B) and, if present, starting material (C) is in the range of 0.3 to 0.

8.

9. The method of claim 1, wherein the solvent-free pressure-sensitive adhesive composition has a viscosity of less than 5,000 mPa·s at room temperature.

10. The method according to claim 1, wherein the hydrosilylation reaction catalyst comprises platinum.

11. The method of claim 1, wherein the starting material (C) is present in an amount of 0 to 6% by weight based on the total weight of the starting material in the solvent-free pressure-sensitive adhesive composition.

12. The method of claim 1, wherein the polyorganohydrosiloxane comprises unit formula (IV): (R 1 3SiO 1 / 2 )2(R 1 2SiO 2 / 2 ) e (HR 1 2SiO 2 / 2 ) f , where R 1 As mentioned above, e ≥ 0, f ≥ 3, and ( e + f The value is between 4 and 500.

13. The method of claim 1, wherein the method is carried out with a solvent of 80 ppm or less by weight, based on the total weight of the starting materials in the solvent-free pressure-sensitive adhesive composition.

14. A solvent-free pressure-sensitive adhesive composition prepared by the method according to any one of claims 1-13.

15. A method for preparing an adhesive article, the method comprising: Optionally (1) the surface of the substrate is treated. (2) Applying the solvent-free pressure-sensitive adhesive composition according to claim 14 to the surface of the substrate, and (3) Curing the solvent-free pressure-sensitive adhesive composition.

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