Bisphenol-cyclic polymethylhydrosiloxane compound and preparation thereof

Abstract

The present invention is a compound of Formula 1: wherein each n is 1, 2 or 3. The compounds of the present invention are useful as adhesion promoters in thermally conductive compositions. The invention also relates to a process for the preparation of the compounds of Formula 1.

Description

BACKGROUND

[0001] In recent years, efficient methods of adhering silicone rubber to incompatible materials such as organic resins have been described. For example, US 6,887,932 discloses the preparation and use of cyclic polymethylhydrosiloxanes containing mono-, di- or triphenylene backbones not directly bonded to silicon atoms. Examples of such compounds include BPA derivatives bonded to terminal cyclic polymethylhydrosiloxane groups through propoxy linkages, as shown:

[0002] wherein n is 1, 2, 3 or 4.

[0003] Unfortunately, the preparation of such adhesion promoters results in the formation of significant amounts of the following by-product which is terminated with only one D H 4group:

[0004] In addition, the preparation of such adhesion promoters requires the use of Pt catalysts which are difficult to remove, thereby adversely affecting the shelf life of the B-part addition cure formulation. Therefore, there is a need to find a reactive adhesion promoter which can be prepared in high yield and purity without Pt catalysts. SUMMARY

[0005] In one aspect, the present invention addresses the needs in the art by providing a compound of Formula 1:

[0006] wherein each n is 1, 2 or 3. The compounds of the present invention can be prepared in high purity and high yield and do not require platinum catalysts and are useful as adhesion promoters in thermally conductive compositions. DETAILED DESCRIPTION

[0007] The present invention is a compound of Formula 1:

[0008] wherein each n is 1, 2 or 3.

[0009] The compound of Formula 1 can be prepared in a single step by dehydrochelation of bisphenol A and a cyclic polymethylhydrosiloxane of Formula 2 in the presence of a catalytic amount of a Lewis acid such as tris(pentafluorophenyl)borane (BCF):

[0010] The reaction temperature is preferably controlled in the range of 20°C to 40°C. The BCF catalyst can be easily removed by treatment with AI2O3, or is completely deactivated at 100°C for 10 minutes. The compounds of the present invention do not require platinum catalysts, which is a significant advantage for the reasons described above.

[0011] The compound of Formula 1 can be used as an adhesion promoter in a thermally conductive composition. Thus, in another aspect, the present invention is a composition comprising a) a compound of Formula 1, b) a di-vinyl terminated poly(di-Ci-C6-alkyl)siloxane, preferably a di-vinyl terminated polydimethylsiloxane having a degree of polymerization (dp) in the range of 8 or 20 or 100 to 600 or to 300; c) an organohydrogenpolysiloxane (Si-H containing polysiloxane) having a dp preferably in the range of 10 to 100; d) thermally conductive filler particles, such as alumina or zinc oxide particles; e) a first filler treatment agent which is a trimethoxysilyl terminated polydimethylsiloxane (PDMS) having a dp preferably in the range of 10 to 150; f) a second filler treatment agent which is a C6-C 20 alkyltrimethoxysilane, such as n-decyltrimethoxysilane; and g) a platinum catalyst. The composition can also contain an inhibitor for the platinum catalyst such as phenylbutynol, and a pigment such as STAN-TONE 40SP03 blue pigment.

[0012] The concentration of the thermally conductive filler particles is preferably in the range of 1000 or 1200 pbw to 1600 or to 1450 pbw per 100 parts by weight (pbw) of the di-vinyl terminated poly(di-Ci-C6-alkyl)siloxane. The thermally conductive filler particles are preferably present in the composition in a multi-modal distribution of alumina or zinc oxide particles or both, the particles having a D 50 particle size in the ranges of 200 nm to 800 nm; 1 pm to 10 pm; and 20 pm to 100 pm as measured by laser diffraction.

[0013] The concentration of the first and second filler treatment agents is preferably in the range of 0.5 to 3 pbw per 100 pbw of the thermally conductive filler particles. The ratio of Si-H groups in the organohydrogenpolysiloxane to vinyl groups of the di-vinyl terminated poly(di-Ci-C6-alkyl)siloxane is preferably in the range of 0.5:1 to 1.1:1, and the ratio of the concentration of Si-H groups in the organohydrogenpolysiloxane to Si-H groups in the compound of Formula 1 is preferably in the range of 0.1:1 to 1:1.

[0014] Examples

[0015] Example 1 - Preparation of a compound of Formula 1 (n = 1)

[0016] Bisphenol A (BPA, 100.3 g), anhydrous toluene (295.2 g, ACS grade), heptane (77.0 g), and 809 g of D H4 g (809 g, available from Gelest) were placed into a 2-L flask. Residual water (from D) was removed by distilling the solvent and then refilling the flask with anhydrous toluene (160.0 g). H 4). The mixture was stirred overnight, and the tris(pentafluorophenyl)borane / toluene catalyst (248 µL of 4.46% BCF) was added to the flask. The flask temperature was maintained between 22°C and 38°C using a dry ice-cooled heating block, and stirring was continued for 3 hours and 50 minutes. Al₂O₃ (23 g) was then added to the flask to remove BCF. Stirring was continued for another 1.5 hours, and the contents of the flask were then filtered through a 0.45 µm membrane. Residual volatiles were removed at 1 Torr and 60°C for 50 minutes to obtain the desired product (278.0 g). 1 H, 13 C and 29 The structure was confirmed by Si NMR spectroscopy.

[0017] Example 2 - Preparation of compounds of Formula 1 (n = 1, 2 and 3)

[0018] BPA (104.3 g), anhydrous toluene (494.5 g, ACS grade), and DOWSIL were added. ™ MH-1109 fluid (791.2 g, a trademark of The Dow Chemical Company or its affiliates) was loaded into a 2-L flask equipped with a thermocouple, mechanical stirrer, and N2 bubbler adapter. The headspace of the flask was purged with N2 for 5 minutes, after which 199 µL of 4.46% BCF catalyst (BCF) was added. The flask temperature was maintained between 22°C and 30°C using a dry ice-cooled heating block. Gas was released during this period, and when the release subsided, an additional amount of BCF / toluene catalyst (57 µL) was added, and this process was repeated 5 times. The contents of the flask were stirred for another 3 hours, followed by the addition of Al2O3 (47 g). Stirring was continued for another 2 hours, and then the contents of the flask were filtered through a 0.45 µm membrane. Residual volatiles were removed at 1 Torr and 60°C for 50 minutes to obtain the desired product (438.6 g). 1 H, 13 C and 29 The structure was confirmed by Si NMR spectroscopy.

[0019] Example 3 - Preparation of thermally conductive compounds

[0020] Vinyl-terminated polydimethylsiloxane (60 mPa·s, 6.5 pbw), trimethoxysiloxy-terminated polydimethylsiloxane (dp=30; 0.7 pbw), and n-decyltrimethoxysilane (0.2 pbw) were loaded into a 1-L planetary mixer, followed by the addition of AES-12 alumina (18.8 pbw) and AL-M734 alumina (20.8 pbw). The mixture was stirred at room temperature for 10 minutes, after which DAM-40K alumina particles (25 pbw) were added. Stirring was continued for 10 minutes, followed by the addition of another amount of DAM-40K alumina particles (25 pbw). Stirring was continued for another 10 minutes, followed by scraping and further mixing for another 10 minutes. The contents were heated under vacuum at 160°C for 60 minutes, and then cooled to room temperature for 30 minutes. STAN-TONE 40SP03 Blue (0.2 pbw), SiH-terminated polyorganosiloxane (dp=14, 2.62 pbw), the compound of Formula 1 from Example 2 (0.06 pbw), and phenylbutyninol (0.01 pbw) were added to a mixer and mixed for 15 minutes, followed by scraping and further vacuum mixing for another 15 minutes. The contents of the mixer were removed; then, platinum 85 catalyst (0.1 pbw, 6000 ppm Pt) was added to the mixture.

[0021] Measurement of hardness

[0022] A mold with a sheet size of 120mm × 120mm × 2mm was used, with PTFE sheets between each sheet in the mold. The composition was placed in the mold to form a sheet with a thickness of 2mm, and cured in a hot press at 120°C for 60 minutes, followed by JIS Type A hardness measurement using a JIS Type A hardness tester. Hardness was measured by stacking three sheets on top of each other. The hardness of each thermally conductive component was also measured after aging at 200°C for 72 hours.

[0023] Thermal conductivity (hot disc)

[0024] Test sheets for thermal conductivity samples were prepared in a mold with dimensions of 50 mm × 30 mm × 6 mm, with PTFE sheets between each plate of the mold. Each composition was placed in the mold to form a sheet with a thickness of 6 mm and cured in a hot press at 120 °C for 60 minutes. The sheets were removed from the mold and stored at 25 °C for 24 hours, after which the thermal conductivity of the two samples was measured using a Hot Disk TPS 500S from Hot Disk AB in Gothenburg, Sweden, and the average value was taken.

[0025] Lap shear strength and cohesive failure rate

[0026] The adhesive strength (MPa) and cohesive failure rate (%) of each thermally conductive component were measured by first cleaning the aluminum die-cast substrate (ADC12) with isopropanol. The composition was filled into an overlapping area defined by an aluminum die-cast substrate with dimensions of 10 mm × 24 mm × 1 mm. While in the overlapping area defined by the substrate, the composition was cured in a hot press at 120 °C for 60 minutes. After curing, excess cured product was removed from the periphery of the overlapping area by a cutter, and the properties were measured by tensile testing at a measurement speed of 50 mm / min.

[0027] Table 1 summarizes the hardness, adhesive strength, and cohesive failure rate of the composition of Example 3.

[0028]

Claims

1. A compound of formula 1: Each n is 1, 2, or 3.

2. Compounds of formula I, where each n is 1.

3. A method comprising the step of contacting bisphenol A with a compound of formula 2 under such conditions in the presence of a Lewis acid catalyst to form a compound of formula 1, wherein the compound of formula 2 is represented by the following structure: ； Furthermore, the compound of Formula 1 is represented by the following structure: ； Each n is 1, 2, or 3.

4. The method according to claim 3, wherein the Lewis acid catalyst is tris(pentafluorophenyl)borane, and the reaction temperature is maintained in the range of 20°C to 40°C.

5. The method of claim 4, wherein each n is 1.

Images