CURABLE COMPOSITIONS, CURED COMPOSITIONS, AND COMPOSITE ARTICLES, AND METHODS FOR MAKING SAME - Patent application

Abstract

A curable composition comprising a siloxane compound and a tetraalkyl orthotitanate. The siloxane compound is represented by the formula -SiH(R 1 m divalent units represented by the formula -Si(R 1 )(OR 2 )O-, and n divalent units of the formula -Si(R 1 p divalent units represented by the formula: 1 each independently represents an alkyl group having 1 to 4 carbon atoms; 2 independently represent H or an alkyl group having 1 to 4 carbon atoms, m and n are integers greater than or equal to 1, and p is an integer greater than or equal to 0. Also disclosed are at least partially cured curable compositions, and composite articles comprising same.

Description

[Background technology]

[0001] Silicone encapsulants are used to protect various components within electronic devices from environmental damage and must adhere well to flexible polymer films, often made from polyimides or thermoplastic polyurethanes. Summary of the Invention

[0002] Many silicone encapsulants do not bond strongly to flexible polymer films such as polyimides and thermoplastic polyurethanes. The present disclosure solves this problem by providing materials and methods that can be used to provide a tie layer to improve bonding of the silicone encapsulant to the polymer film.

[0003] In a first aspect, the present disclosure provides a curable composition comprising: (i) formula [ka] m bivalent units represented by formula [ka] n divalent units represented by formula [ka] p bivalent units represented by [In the formula, each R 1 each independently represents an alkyl group having 1 to 4 carbon atoms; 2 each independently represents H or an alkyl group having 1 to 4 carbon atoms, m and n are integers of 1 or greater, and p is an integer of 0 or greater. A siloxane compound comprising: (ii) a tetraalkyl orthotitanate.

[0004] In another aspect, the present disclosure provides a curable composition according to the present disclosure that is at least partially cured.

[0005] In yet another aspect, the present disclosure provides a composite article, comprising: A substrate having a main surface; a tie layer disposed on a major surface of a substrate, the tie layer comprising an at least partially cured curable composition according to the present disclosure.

[0006] In yet another aspect, the present disclosure provides a method of making a composite article, comprising: providing a substrate having a bonding layer disposed on a surface thereof, the bonding layer comprising an at least partially cured curable composition according to the present disclosure; contacting a curable silicone-containing resin with a tie layer; and at least partially curing the curable silicone-containing resin.

[0007] As used herein, The term "siloxane compound" refers to a compound having a molecular structure based on a chain of alternating silicon and oxygen atoms with organic groups bonded to the silicon atoms. The term "tie layer" refers to a layer that, when placed between different adherends, can improve the adhesion between them. The tie layer does not have to be placed between two adherends in all cases (e.g., it may be placed on a single substrate, like a primer).

[0008] The features and advantages of the present disclosure will be further understood by considering the detailed description and the appended claims. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic side view of an exemplary composite article 100 according to the present disclosure.

[0010] Repeat use of reference characters in the specification and drawings is intended to represent the same or similar features or elements of the present disclosure. It is to be understood that those skilled in the art can devise numerous other modifications and embodiments that are within the scope and spirit of the principles of the present disclosure. The figures may not be drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The curable composition according to the present disclosure includes a siloxane compound and a tetraalkyl orthotitanate.

[0012] The siloxane compound is formula [ka] m bivalent units represented by formula [ka] n divalent units represented by formula [ka] The compound includes p divalent units represented by

[0013] Each R 1 independently represent an alkyl group having 1 to 4 carbon atoms. Examples include methyl, ethyl, propyl, and butyl.

[0014] Each R 2 independently represent H or an alkyl group having 1 to 4 carbon atoms. Examples include H, methyl, ethyl, propyl, and butyl.

[0015] In some embodiments, each R 1 and R 2 is methyl. In some embodiments, each R 1 is methyl, and each R 2 is ethyl.

[0016] Both m and n independently represent an integer of 1 or greater (e.g., ≧1, ≧2, ≧3, ≧4, ≧5, ≧10, ≧15, ≧20, or ≧50) and p represents an integer of 0 or greater (e.g., ≧0, ≧1, ≧2, ≧3, ≧4, ≧5, ≧10, ≧15, ≧20, or ≧50). In some embodiments, the relative ratio m:n:p is 1-5:1-20:0-50. In some embodiments, the ratio m:n (i.e., m / n) is in the range of 1:20-20:1 (inclusive), preferably 1:25-1.35 (inclusive).

[0017] In some embodiments, the siloxane compound is linear. In these embodiments, the siloxane compound may comprise a linear polymer. In some embodiments, the linear polymer has a number average molecular weight (M) of 400 grams / mole to 10,000 grams / mole, preferably 500 grams / mole to 2,000 grams / mole. n ), although higher and lower molecular weights may also be used.

[0018] The aforementioned type of siloxane compound is, for example, -OSiH(R 1 )O- and optionally -OSi(R 1 ) 2O-difunctional silicones can be prepared by reaction of some of the hydride groups on the silicone with an alkanol, which results in replacement of the hydride with the corresponding alkoxide, as generally shown in Scheme I below. [ka] [In the formula, R 1 and R 2 is as defined above, a and x represent integers of 1 or more, and b represents an integer of 0 or more. * represents an additional unspecified structure consisting of a combination of Si, C, H, and / or O atoms (e.g., trimethylsiloxy and methyl, respectively), or two * may join together to form a covalent bond resulting in a cyclic structure as described herein below.

[0019] Trimethylsiloxy-terminated methylhydrosiloxane-dimethylsiloxane copolymers suitable for use in the above reaction can be made by conventional methods and / or commercially available from, for example, Gelest Inc., Morrisville, Pennsylvania (e.g., Product Codes: HMS-013, HMS-031, HMS-053, HMS-064, HMS-071, HMS-082, HMS-151, HMS-301, HMS-401, HMS-501, HMS-601, HMS-701, HMS-801, HMS-901, HMS-101, HMS-111, HMS-121, HMS-131, HMS-141, HMS-151, HMS-161, HMS-171, HMS-181, HMS-191, HMS-201, HMS-211, HMS-221, HMS-231, HMS-241, HMS-251, HMS-261, HMS-271, HMS-301, HMS-311, HMS-321, HMS-331, HMS-341, HMS-351, HMS-361, HMS-371, HMS-401, HMS-411, HMS-421, HMS-431, HMS-441, HMS-451, HMS-501, HMS-511, HMS-521, HMS-531, HMS-541, HMS-551, HMS-601, HMS-701, HMS-801, HMS-901, HMS-101, HMS-111, HMS-121, HMS-131, HMS-141, HMS-151, HMS-161, HMS-171, * and HMS-501); SiSiB Silanes and Silicones, Nanjing, China (e.g., under the trade name SISIB HF2050 in grades 100H75, 15H75, 55H55, 22H55, 60H36, 15H36, 15H100, 60H120, 15H43, 115H41, 21H20, 70H18, and 20H11); or Dow Corning, Midland, Michigan (e.g., under the trade name SYL-OFF 7678).

[0020] In some embodiments, the siloxane compound is cyclic. Exemplary such siloxane compounds are of the formula [ka] [In the formula, R 1 and R 2 is as previously defined, and c is 0, 1, or 2. It can be expressed as:

[0021] Combinations of cyclic siloxane compounds and combinations of linear siloxane compounds may be used. Combinations of cyclic and linear siloxane compounds may also be used.

[0022] Tetraalkyl orthotitanate has the formula [ka] wherein each R independently represents an alkyl group. In some preferred embodiments, each R independently has 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. Examples of R include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-heptyl, n-octyl, isooctyl, 2-ethyl-1-hexyl, n-decyl, and n-dodecyl. Typically, all four R groups are the same, although this is not a requirement.

[0023] Tetraalkyl orthotitanates can be made, for example, by reaction of titanium tetrachloride with an alkanol, or they may be obtained from commercial sources such as Sigma-Aldrich Chemical Co., Saint Louis, Missouri, or DuPont, Wilmington, Delaware.

[0024] The tetraalkyl orthotitanate catalyzes the crosslinking of the siloxane compound through hydrosilylation of the alkoxy group and the generation of the corresponding alcohol. The amount of tetraalkyl orthotitanate relative to the siloxane compound can be any amount, depending, for example, on relative molecular weight and / or equivalent weight. In many embodiments, the tetraalkyl orthotitanate is present in an amount of 5 percent or less based on the combined weight of the tetraalkyl orthotitanate and the siloxane compound.

[0025] In some embodiments, the curable composition further comprises at least one trialkoxysilane, preferably having from 3 to 18 carbon atoms, more preferably from 3 to 12 carbon atoms, more preferably from 3 to 6 carbon atoms. Exemplary trialkoxysilanes include trimethoxysilane, triethoxysilane, tripropoxysilane, and tributoxysilane.

[0026] Typically, the hardenable composition is essentially free of water, i.e., does not contain more than unintentional incidental amounts of water (e.g., less than 0.01 weight percent, less than 0.001 weight percent, or even less than 0.0001 weight percent water).

[0027] The curable composition can be at least partially cured (e.g., cured to at least a non-flowable state or fully cured) by the application of thermal energy, for example, by heating in an oven at about 80° C. or by using a heat lamp or heat gun.

[0028] The curable composition can be applied to a substrate and at least partially cured (preferably fully cured) to provide a bonding layer when contacted with another material, such as, for example, a silicone encapsulant resin.

[0029] 1 thus illustrates a composite article 100 including a substrate 110 having a major surface 112 and a tie layer 120 disposed on major surface 112. The tie layer includes an at least partially cured curable composition according to the present disclosure. An optional silicone elastomer 130 layer is disposed over at least a portion of tie layer 120.

[0030] Exemplary substrates include flexible films (and other flexible substrates) including polymers such as, for example, polyimides, thermoplastic polyurethanes, polyesters, polyolefins (e.g., polyethylene and polypropylene), polyamides, and acrylics, particularly those used in electronics applications (e.g., polyimides and thermoplastic polyurethanes). Substrates may also be rigid (e.g., epoxy circuit boards) or a combination of flexible and rigid. Substrates may include inorganic materials such as glass or ceramics, or organic materials such as organic polymers or wood.

[0031] The curable composition may be applied to the substrate by any suitable method, including, for example, spraying, roll coating, inkjet printing, screen printing, dip coating, knife coating, curtain coating, brush coating, bar coating, slot coating, and wire wound rod coating. Any desired thickness may be used. In many embodiments, the curable composition is applied at a dried and / or cured thickness of 0.5 microns to 10 microns.

[0032] To facilitate coating / printing, the curable composition may contain an optional amount of organic solvent (eg, ethyl acetate and / or heptane).

[0033] In some embodiments, a curable silicone-containing resin can be placed on the bonding layer and cured.Any curable silicone-containing resin can be used.Examples include RTV and moisture-curable silicone resins.In some preferred embodiments, the curable silicone-containing resin can be cured by hydrosilylation reaction and contains an effective amount of hydrosilylation catalyst.Exemplary hydrosilylation-curable silicone resins include the mixture of hydride-containing silicone and vinyl-containing silicone resins combined with hydrosilylation catalyst.

[0034] Hydrosilylation, also called catalytic hydrosilylation, refers to the addition of a Si-H bond to an unsaturated bond. Hydrosilylation reactions are typically catalyzed by platinum catalysts and generally involve the application of heat to effect the reaction. In this reaction, Si-H is added to a double bond to form new C-H and Si-C bonds. This process is described, for example, in WO 2000 / 068336 (Ko et al.), WO 2004 / 111151 (Nakamura), and WO 2006 / 003853 (Nakamura).

[0035] Useful hydrosilylation catalysts can include thermal catalysts (which can be activated at room temperature or higher) and / or photocatalysts. Among these, photocatalysts may be preferred due to their long-term storage stability and ease of handling. Exemplary thermal catalysts include platinum complexes such as HPtCl (Speiller's catalyst), coordination complexes such as platinum and divinylsiloxane (Karstedt's catalyst), and organometallic platinum complexes such as tris(triphenyl-phosphine)-rhodium(I) chloride (Wilkinson's catalyst).

[0036] Useful platinum photocatalysts are disclosed, for example, in U.S. Patent No. 7,192,795 (Boardman et al.) and references cited therein. Certain preferred platinum photocatalysts are selected from the group consisting of Pt(II) β-diketonate complexes (such as those disclosed in U.S. Patent No. 5,145,886 (Oxman et al.)), (η5-cyclopentadienyl)tri(σ-aliphatic)platinum complexes (such as those disclosed in U.S. Patent No. 4,916,169 (Boardman et al.), U.S. Patent No. 4,510,094 (Drahnak)), and C7-20-aromatically substituted (η5-cyclopentadienyl)tri(σ-aliphatic)platinum complexes (such as those disclosed in U.S. Patent No. 6,150,546 (Butts)). The hydrosilylation photocatalyst is activated, for example, by exposure to actinic radiation, typically ultraviolet light, according to known methods.

[0037] The amount of hydrosilylation catalyst can be any effective amount, in some embodiments, the amount of hydrosilylation catalyst is from about 0.5 parts by weight to about 30 parts by weight of platinum per million parts by weight of the total composition in which it is present, although greater or lesser amounts can be used.

[0038] Hydrosilylation-curable silicone resins are commercially available and / or can be made according to known methods, such as those described in U.S. Pat. No. 10,793,681 (Sweier et al.) and U.S. Patent Application Publication No. 2021 / 0032469 (Hayashi et al.). Commercial sources of hydrosilylation-curable silicone resins include Shin-Etsu Chemical Co., Ltd., Tokyo, Japan; Dow Silicones, Midland, Michigan; Momentive Performance Materials, Waterford, New York; Wacker Chemicals, Adrian, Missouri, and Gelest, Inc, Morrisville, Pennsylvania.

[0039] Objects and advantages of the present disclosure are further illustrated by the following non-limiting examples, but the specific materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit the disclosure. EXAMPLES

[0040] All parts, percentages, ratios, etc. in the examples are by weight unless otherwise noted. All reagents used in the examples were obtained or available from common chemical suppliers, such as, for example, Sigma-Aldrich, Inc. (Saint Louis, Missouri), or can be synthesized by conventional methods.

[0041] The materials used in the examples are reported in Table 1 below.

[0042] [Table 1]

[0043] Preparation of cyclic poly(ethoxymethyl-co-methylhydro)siloxane (polymer 1) SYL-OFF 7048 (10 g, 166.7 mmol of SiH) was mixed with ethanol (3.8 g, 82.6 mmol) in a 100 mL round-bottom flask, followed by the addition of Pd / C (0.008 g) at room temperature under nitrogen. The addition of Pd / C resulted in the rapid evolution of hydrogen gas, indicating the replacement of ethoxy groups. After stirring at room temperature for 4-5 h, Fourier transform infrared (FT-IR) spectroscopy of the reaction mixture (ca. 2160 cm -1 The reaction was confirmed to be complete by analysis (Si-H reduction at 200 rpm). To isolate the product, the Pd / C was filtered off using a 1.0 micron glass filter and then the unreacted / residual ethanol was evaporated using vacuum.

[0044] Preparation of cyclic poly(methoxymethyl)-co-poly(methylhydro)siloxane (Polymer 2) SYL-OFF 7048 (10 g, 166.7 mmol of SiH) was mixed with methanol (2.5 g, 54.3 mmol) in a 100 mL round-bottom flask, followed by the addition of Pd / C (0.008 g) at room temperature under nitrogen. The addition of Pd / C resulted in the rapid evolution of hydrogen gas, indicative of the replacement of methoxy groups. After stirring at room temperature for 4-5 h, FT-IR spectroscopy of the reaction mixture (~2160 cm) showed a 1:1 ratio of 1:1. -1 The reaction was confirmed to be complete by analysis (Si-H reduction at 200 rpm). To isolate the product, the Pd / charcoal was filtered off using a 1.0 micron glass filter and then the unreacted / residual methanol was evaporated using vacuum.

[0045] Preparation of Linear Poly(ethoxymethyl)-co-poly(dimethyl)-co-poly(methylhydro)siloxane (Polymer 3) Syl-Off 7678 (10 g, 116.9 mmol of SiH) was mixed with ethanol (1.0 g, 21 mmol) in a 100 mL round-bottom flask, followed by the addition of Pd / C (0.008 g) at room temperature under nitrogen. The addition of Pd / C resulted in the rapid evolution of hydrogen gas, indicative of the replacement of ethoxy groups. After stirring at room temperature for 4-5 h, FT-IR spectroscopy of the reaction mixture (~2160 cm) revealed a 1:1 ratio of 1:1. -1The reaction was confirmed to be complete by analysis (Si-H reduction at 200 rpm). To isolate the product, the Pd / C was filtered off using a 1.0 micron glass filter and then the unreacted / residual ethanol was evaporated using vacuum.

[0046] Preparation of Linear Poly(methoxymethyl)-co-poly(dimethyl)-co-poly(methylhydro)siloxane (Polymer 4) SYL-OFF 7678 (10 g, 116.9 mmol of SiH) was mixed with methanol (0.8 g, 25 mmol) in a 100 mL round-bottom flask, followed by the addition of Pd / C (0.008 g) at room temperature under nitrogen. The addition of Pd / C resulted in the rapid evolution of hydrogen gas, indicative of the replacement of methoxy groups. After stirring at room temperature for 4-5 h, FT-IR spectroscopy of the reaction mixture (~2160 cm) showed a 1:1 ratio of 1:1. -1 The reaction was confirmed to be complete by analysis (Si-H reduction at 100° C.). To isolate the product, the Pd / C was filtered off using a 1.0 micron glass filter, and then the unreacted / residual methanol was evaporated using vacuum.

[0047] Examples EX1 to EX18 and Comparative Examples CE1 to CE3 A curable composition was prepared by mixing the materials listed in Table 2 below in 100 grams of a heptane / ethyl acetate mixture (70:30 by weight).

[0048] [Table 2]

[0049] Coating the tie layer onto the substrate The curable compositions in Table 2 were coated onto PI or TPU film samples using a No. 3 wire wound rod from RD Specialties, Webster, New York (nominal wet thickness 0.05 mm) and then heated in an 80° C. oven for 15 to 60 seconds to remove the solvent and cure the curable compositions.

[0050] Silicone Encapsulation, Coating, and Curing Preparation of UV-cured silicones: DMS-V46 (100 grams) or DMS-S45 (100 grams), SYL-OFF 7678 (1.0 grams) were mixed in a 250.0 g opaque plastic bottle. Then, 50 ppm of Pt catalyst-1 mixture was added. Pt catalyst-1 mixture was prepared as 2 wt% Pt catalyst in toluene. To test the adhesion of the silicone elastomer on the substrate film, the silicone material was coated onto the film using a knife coater. To compare the duration of cure, all coated silicone materials were kept at a thickness of 0.025 centimeters. The cure of the films was carried out under a benchtop UV curing system equipped with two 15 watt 350 nm black UV lamps. The lamps were maintained at a height of 2.0 inches above the sample during cure.

[0051] Preparation of heat-cured silicone: VQM-146 (100 grams), SYL-OFF 7678 (5.0 grams), and diallyl maleate (50 ppm relative to VQM) were mixed in a 250.0 g plastic bottle. Then, 50 ppm of Karstedt's catalyst was added. Testing the adhesion of silicone elastomers on substrate films. The silicone formulations were coated onto substrate films (e.g., polyimide) using a knife coater. All coated silicone materials were kept at a thickness of 0.025 centimeters to compare the duration of cure. The films were cured at 120°C / 1-2 min in a benchtop oven.

[0052] Measurement of adhesion between cured silicone elastomer and substrate film Silicone elastomer / encapsulant adhesion was measured by manually peeling the cured silicone elastomer from the substrate film and recording adhesive or cohesive failure of the silicone elastomer / encapsulant. Adhesive failure is indicated by easy and clean peeling of the encapsulant without leaving any residue, and cohesive failure is measured by tearing of the encapsulant during peeling or the presence of encapsulant remaining on the film. The adhesion results are summarized in Table 3 (adhesion to PI film) and Table 4 (adhesion to TPU film).

[0053] [Table 3]

[0054] [Table 4]

[0055] The preceding description is intended to enable one skilled in the art to practice the disclosure as set forth in the claims and should not be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereof.

Claims

1. A composite article, comprising: a substrate having a main surface; a tie layer disposed on the major surface of the substrate; a silicone elastomer in contact with the tie layer; Including, The tie layer comprises an at least partially cured curable composition, the curable composition comprising: (i) formula 【Chemical 1】 m divalent units represented by formula 【Chemistry 2】 n divalent units represented by formula 【Chemistry 3】 p bivalent units represented by [In the formula, each R １ independently represent an alkyl group having 1 to 4 carbon atoms, and each R ２ each independently represents H or an alkyl group having 1 to 4 carbon atoms, m and n are integers of 1 or greater, and p is an integer of 0 or greater. a siloxane compound comprising: (ii) tetraalkyl orthotitanate; and Composite articles, including:

2. The composite article of claim 1, wherein said tetraalkyl orthotitanate comprises tetrakis(2-ethylhexyl) titanate.

3. 3. The composite article of claim 1 or 2, wherein p is 0 and the siloxane compound is cyclic.

4. 3. The composite article of claim 1 or 2, wherein the ratio of m:n:p is 1-5:1-20:0-50.

5. 5. The composite article of claim 4, wherein the ratio of m:n is in the range of 1:20 to 20:1 inclusive.

6. 3. The curable composition of claim 1 or 2, further comprising at least one trialkoxysilane.

7. 3. The composite article of claim 1 or 2, wherein the substrate comprises a polymer film, the polymer film comprising at least one of a polyimide or a polyurethane.

8. 1. A method of manufacturing a composite article, comprising: providing a substrate having a bonding layer disposed on a surface thereof; disposing a curable silicone-containing resin on the tie layer; at least partially curing the curable silicone-containing resin; Including, The tie layer comprises an at least partially cured curable composition, the curable composition comprising: (i) formula 【Chemistry 4】 m divalent units represented by formula 【Chemistry 5】 n divalent units represented by formula 【Chemistry 6】 p bivalent units represented by wherein each R 1 independently represents an alkyl group having 1 to 4 carbon atoms, each R 2 independently represents H or an alkyl group having 1 to 4 carbon atoms, m and n are integers of 1 or greater, and p is an integer of 0 or greater. a siloxane compound comprising: (ii) tetraalkyl orthotitanate; and A method comprising:

9. The method of claim 8 , wherein the at least partially curing the curable silicone-containing resin comprises photocuring.

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