Polyphenylsiloxane with anhydride functionalized adhesion promoter

Abstract

The present invention addresses a need in the art by providing a composition comprising: a) a compound of Formula 1: (I) b) a divinyl-terminated polyphenylsiloxane; c) a vinyl-terminated polyphenylsiloxane resin; d) a hydrogenphenylsiloxane; and e) a hydrosilylation catalyst; where R, DH, x, m, and n are as defined herein. The composition of the present invention is useful as a coating for electronic devices.

Description

[0001] Polyphenylsiloxane with Anhydride Functionalized Adhesion Promoter

[0002] Background of the Invention

[0003] The present invention relates to a composition comprising a polyphenylsiloxane and an anhydride functionalized adhesion promoter. Polyphenylsiloxanes are widely used in coatings for applications that require optical clarity and high modulus such as electronic devices because of their high refractive index and good mechanical properties. Unfortunately, the inherent hardness of these coatings causes them to readily delaminate from a variety of substrates to which they are adhered. Inasmuch as the properties of hardness and adhesion are both desirable, it would be an advance in the art of coatings for electronic devices to find compositions that form coatings with optical clarity, acceptable hardness, and excellent adhesion.

[0004] Summary of the Invention

[0005] The present invention addresses a need in the art by providing a composition comprising: a) a compound of Formula 1 :

[0006] Formula 1 b) a divinyl-terminated polyphenylsiloxane; c) a vinyl-terminated polyphenylsiloxane resin; d) a hydrogenphenylsiloxane; and e) a hydrosilylation catalyst; where each R is a Cs-Cn-alkyl anhydride group; the sum of m and n is in the range of from 1 to 4; and -DHX- is a mono- or diradical of the compound of Formula 2:

[0007] Formula 2 where x is from 3 to 10, and y is x - 3.

[0008] The composition of the present invention is useful as a coating for electronic devices.

[0009] Detailed Description of the Invention The present invention is a composition comprising: a) a compound of Formula 1 :

[0010] Formula 1 b) a divinyl-terminated polyphenylsiloxane; c) a vinyl-terminated polyphenylsiloxane resin; d) a hydrogenphenylsiloxane; and e) a hydrosilylation catalyst; where each R is a Cs-Ci2-alkyl anhydride group; the sum of m and n is in the range of from 1 to 4; and -DHX- is a mono- or diradical of the compound of Formula 2:

[0011] Formula 2 where x is from 3 to 10, and y is x - 3.

[0012] Examples of suitable anhydride substituents for the compound of Formula 1 include succinic anhydride, maleic anhydride, oxalic anhydride, and phthalic anhydride groups. Where the anhydride group is a succinic anhydride group, R is represented by the following fragment: where z is from 1 to 10, and where the dotted line represents the point of attachment to the DHXdiyl group.

[0013] DHXis represented by the compound of Formula 2. When x is 4, y is 1. Thus, DH4 is represented by the compound of Formula 2a:

[0014] Formula 2a

[0015] In one embodiment, m is 1, n is 1, y is 1, and z is 1. Accordingly, a possible configuration of a compound of the present invention is represented by Formula 3:

[0016] It is understood that the R groups can be attached to any of the Si atoms of the DHXgroups and that the DHXgroups may be a blend of DHXgroups. For example, DHXmay be a mixture of DH4, DH5, and DH6. It is further understood that the compound of Formula 1 may comprise a blend of mono-, di-, tri-, and tetrasubstituted alkyl anhydride groups. In one embodiment, the compound of Formula 1 comprises a blend of mono- and disubstituted alkyl anhydride groups; i.e., m + n is in the range of 1 to 2. The concentration of the compound of Formula 1 is preferably in the range of from 0.2 to 5 weight percent, based on the weight of the composition. The compound of Formula 1 (where m is 1 and n is 1) can be prepared in 2-steps, as illustrated: where Formula lois represented by the following formula:

[0017] Formula l0and Anh is an anhydride group. An example of a suitable acid catalyst is tris(pentafluorophenyl)borane (BCF).

[0018] The term “divinyl-terminated polyphenylsiloxane” refers to a compound of the following Formula 4: where Ph is phenyl; each R' is independently Ci-Ce-alkyl or phenyl; and n is from 1 or from 5 or from 10 to 500 or to 200 or to 100. Preferred Ci-CT-alkyl groups are methyl groups. Preferably, each R' is methyl. Preferably, the concentration of the divinyl-terminated polyphenylsiloxane, is in the range of from 1 or from 2 or from 4 weight percent, to 10 or to 8 weight percent, based on the weight of the composition.

[0019] The vinyl-terminated polyphenylsiloxane resin is conveniently prepared by reacting together a tri-Ci-Ce-alkoxyphenylsilane and a compound of Formula 5:

[0020] Formula 5 where n' is from 1 to 20, preferably to 10, and more preferably to 5; most preferably, n' is 1 and each R' is methyl. This most preferred vinyl-terminated polyphenylsiloxane resin - MMePhV1aTPhb, where a and b are mole fractions - can be conveniently prepared by contacting trimethoxyphenylsilane with l,3-dimethyl-l,3-diphenyl-l,3-divinyldisiloxane in the presence of an acid catalyst. Mole fraction “a” is preferably in the range of from 0.10 to 0.40 and mole fraction “b” is preferably in the range of from 0.60 to 0.90.MCPIIV1is represented by the following fragment: and TPhis represented by the following fragment: where the dotted lines represent bonds to other silicon atoms in the vinyl -terminated polyphenylsiloxane resin. Preferably, the concentration of the vinyl-terminated polyphenylsiloxane resin is in the range of from 50 to 80 weight percent, based on the weight of the composition.

[0021] The term “hydrogenphenylsiloxane” refers to a compound of Formula 6:

[0022] Formula 6 where each R is independently Ci-Ce-alkyl or phenyl; and m is from 1 to 50 or to 20 or to 10. Preferably m is 1. Preferred Ci-Ce-alkyl groups are methyl groups. Preferably, each R is phenyl. Preferably, the concentration of the hydrogenphenylsiloxane is in the range of from 10 to 30 weight percent.

[0023] The hydrosilylation catalyst is a catalyst that promotes hydrosilylation. Examples of suitable hydrosilylation catalysts include platinum(II) acetoacetonate, platinum(O) 1,3-divinyl-l, 1,3,3- tetramethyldisiloxane complex and trimethyl(methylcyclopentadienyl)platinum (IV). The composition may further contain an inhibitor for the platinum catalyst such as phenylbutynol or methyl(tris(l,l-dimethyl-2-propynyl) oxy) silane, and a pigment such as STAN-TONE 40SP03 Blue pigment.

[0024] The composition of the present invention forms optically clear, hard, and non-delaminating coatings for a variety of substrates such as paper, metal, plastic, and glass.

[0025] Examples

[0026] Intermediate Example 1 - Preparation of Formula lo A compound of Formula 2 (99.97 g, y is predominantly 1) then anhydrous toluene (49.97 g) were added to a N2 purged 1-L 3-neck round bottom flask equipped with a thermocouple, an overhead stirrer, and a septum. The contents of the flask were stirred, then BCF catalyst solution (0.32 g, 1% wt.% in toluene) was added. Diphenyldisilanol (56.07 g) was added in 4 portions over the course of ~1.5 h while maintaining a reaction temperature < 30 °C. The contents were stirred for an additional 1.5 h after addition was complete. A clear solution was obtained and treated with 36 pF of phenyl acetylene before volatiles were removed in vacuo at 80 °C.

[0027] Intermediate Example 2 - Preparation of a Compound of Formula 3

[0028] Formula 3

[0029] The compound of Formula lo(81.0 g) was charged into a three-neck round bottom flask and heated to 75 °C under N2 with stirring. Karstedt’s catalyst (5 ppm) was added, followed by the gradual addition of an allyl succinic anhydride solution (29.0 g in 7 g toluene). The addition rate was controlled so that the reaction mixture temperature did not exceed 80 °C. After completion of the addition, the reaction mixture was stirred at 75 °C under N2 for additional 1 h being allowed to cool to room temperature. 1-Ethynyl-l -cyclohexanol (0.43 g) was added to the mixture, after which time volatiles were removed in vacuo.

[0030] Examples

[0031] In the following examples, trimethyl(methylcyclopentadienyl)platinum (IV) is a solution of 1 part-by-weight (pbw) trimethyl(methylcyclopentadienyl)platinum (IV) diluted with 99 pbw of methyltrimethoxysilane; and Karstedt’s catalyst (platinum(O) 1,3-diethenyl-l, 1,3,3- tetramethyldisiloxane in 70 wt% isopropanol) is a solution of 0.5 pbw of Karstedt’s catalyst diluted with 99.5 pbw methyltrimethoxy silane.

[0032] Example 1 - Preparation and UV-Curing of a Resin Composition with Trimethyl(methylcyclopentadienyl)platinum (IV) Catalyst and Adhesion Promoter

[0033] MViDPh23MV1(6.49 pbw), polymethyphenylsiloxane resin (MMePhVio.23TPho.77, 68.08 pbw); 1, 1,5,5- tetramethyl-3,3-diphenyltrisiloxane (20.43 pbw); methyl(tris(l,l-dimethyl-2-propynyl) oxy) silane (0.0008 pbw); and Intermediate Example 2 (1 pbw) adhesion promoter were added to a vessel and mixed at 1,500 rpm for 2 min, followed by addition of Reolosil DM-30S fumed silica filler (3 pbw). Mixing was continued at 2,000 rpm for 2 min, then hand-mixed, then mixed again at 2,000 rpm for 2 min. Then, trimethyl(methylcyclopentadienyl)platinum (IV) (1 pbw) was added to the blend and mixing was continued at 1,500 rpm for an additional 2 min. The sample was cured by LED UV (Firejet FJ800) equipment with 365 nm and energy 5,000 mJ / cm2dosage of UVA; cure was completed by heating the sample to 70 °C for 30 min.

[0034] Example 2 - Preparation and Heat-Curing of a Resin Composition with Platinum, 1,3-Diethenyl-

[0035] 1.1.3.3-Tetramethyldisiloxane Catalyst and Adhesion Promoter

[0036] The procedure as described for Example 1 was repeated, except that Karstedt’s catalyst (0.04 pbw) was used as the catalyst. The sample was cured at 150 °C for 1 h.

[0037] Comparative Example 1 - Preparation and UV-Curing of a Resin Composition with Trimethyl(methylcyclopentadienyl)platinum (IV) Catalyst Without Adhesion Promoter

[0038] The procedure was carried out substantially described in Example 1 except that the adhesion promoter of Intermediate 2 was excluded from the mixture.

[0039] Comparative Example 2 - Preparation and Heat-Curing of a Resin Composition with Platinum,

[0040] 1.3-Diethenyl- 1 , 1,3,3-Tetramethyldisiloxane Catalyst Without Adhesion Promoter

[0041] The procedure was carried out substantially described in Example 2 except that the adhesion promoter of Intermediate 2 was excluded from the mixture.

[0042] Peel Strength Testing Procedure

[0043] Two thermoplastic Ultradur B 4300 G4 Polybutylene Terephthalate 25 -mm x 100-mm substrates with a thickness of 3 mm were cleaned with isopropanol and dried for 18 h at 120 °C. The thermoplastic substrates were preheated at 150 °C for 5 min prior to overmolding with the LSR. Substrates were overmolded with a 3-mm layer of the LSR formulation, and compression molded for 5 min at 150 °C at a pressure of 300 bar.

[0044] Adhesion was tested in a 90° peel test using a floating roller device as described in DIN EN ISO 22631 (“Adhesives - Test method for adhesives for floor and wall coverings”). A tensile tester was used at a pulling speed of 100 mm / min.

[0045] Crosshatch Procedure

[0046] ASTM D3359 was used to measure the area removed on a coated glass slide. The coated surface was etched in a crosshatched fashion and tested. The crosshatch test classifications are illustrated in Table 1.

[0047] Table 1 - Crosshatch Test Classifications

[0048] Adhesion Lap Shear Testing

[0049] Lap shear testing was carried out using an Instron 3366 mechanical testing system. The cured samples (10-mm thick) were sandwiched between two 0.5-mm thick glass or aluminum (Al) substrates; each substrate was pulled and pushed parallel to the sample until breakage occurred due to adhesive failure (AF), cohesive failure (CF), or substrate failure (SF). The results of the adhesion lap shear, crosshatch testing, and failure modes of the samples are illustrated in Table 2.

[0050] Table 2 - Adhesion Lap Shear, Crosshatch, and Failure Mode of Cured Coated Substrates

[0051] The data show that the samples with the adhesion promoter met all the desired criteria of high adhesion lap shear strength, cohesive failure, and excellent crosshatch properties for the substrates tested.

Claims

Claims:

1. A composition comprising: a) a compound of Formula 1 :Formula 1 b) a divinyl-terminated polyphenylsiloxane; c) a vinyl-terminated polyphenylsiloxane resin; d) a hydrogenphenylsiloxane; and e) a hydrosilylation catalyst; where each R is a Cs-Ci2-alkyl anhydride group; the sum of m and n is in the range of from 1 to4; and -DHX- is a mono- or diradical of the compound of Formula 2:Formula 2 where x is from 3 to 10, and y is x - 3.

2. The composition of Claim 1 wherein x is in the range of from 4 to 6; and m + n is in the range of from 1 to 2; wherein the divinyl-terminated polyphenylsiloxane is a compound of the following formula:where Ph is phenyl, each R' is independently methyl or phenyl; and n is from 5 to 200;3. The composition of Claim 2 where x is 4; wherein the vinyl-terminated polyphenylsiloxane resin is the reaction product of a tri-Ci-Ce-alkoxyphenylsilane and a divinyl-terminated polyphenylsiloxane of the following formula:where n' is 1, and each R' is methyl; and wherein hydrogenphenylsiloxane is a compound of the following formula:where each R is independently Ci-Ce-alkyl or phenyl; and m is from 1 to 10.

4. The composition of Claim 3 wherein each R is represented by the following fragment:where each z is from 1 to 10, and where the dotted line represents the point of attachment to the DHXdiyl group; wherein m is 1, and R is phenyl.

5. The composition of Claim 4 wherein the vinyl-terminated polyphenylsiloxane resin is of the form MMePhV1aTPhb, where a and b are mole fractions, where mole fraction “a” is in the range of from 0.10 to 0.40 and mole fraction “b” is in the range of from 0.60 to 0.90.

6. The composition of Claim 2 wherein the hydrosilylation catalyst is a platinum catalyst.

7. The composition of Claim 4 where each z is 1; wherein the platinum catalyst is platinum(II) acetoacetonate, platinum(O) l,3-divinyl-l,l,3,3-tetramethyldisiloxane complex or trimethyl(methylcyclopentadienyl)platinum (IV) .

8. The composition of Claim 6 which further comprises an inhibitor for the platinum catalyst.

9. The composition of Claim 7 which further comprises phenylbutynol or methyl(tris(l,l- dimethyl-2-propynyl) oxy) silane.

10. The composition of Claim 1 which is represented by Formula 3:

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