TW202407064A - Polysiloxane filler treating agent and compositions prepared therewith - Google Patents

Abstract

The present invention relates to a composition comprising: (a) a polyorganosiloxane; (b) filler particles; and (c) a filler treating agent of Formula I: where R1, R2, m, n, p, and q are as defined herein. The composition is useful as a thermally conductive formulation.

Description

Polysiloxane filler treatment agent and compositions prepared therefrom

The present invention relates to a filler treatment agent based on polysiloxane and its application in thermal conductive formulations.

Increased demand for thermally conductive composite materials has driven the discovery of thermally conductive formulations that provide more even and efficient heat dissipation for integrated circuits, battery packs, microelectronic circuit systems, and electric motors. The main components of conventional thermal conductive formulations are matrix polymer, inorganic filler particles, and filler treating agent (FTA). Inorganic particles are inexpensive components of thermally conductive formulations and provide heat dissipation. Therefore, what is desired is a high level of loading and uniform dispersion of filler particles into the matrix polymer; however, uniform dispersion is challenging because filler particles are often incompatible with the matrix polymer, leading to phase separation. FTA, which has a chemical function that is compatible with both the matrix polymer and the filler particles, promotes compatibility and improves the dispersion of the filler particles and the matrix by associating with the surface of the inorganic particles. An example of a commercially available FTA is monotrimethoxysiloxy-terminated polydimethylsiloxane, which is represented by the following formula: (See US 7,592,383 B2, column 6). Unfortunately, although this and other structurally similar FTA's are high performing, they are very expensive because they are prepared through multi-step synthetic procedures and numerous purification steps that require the use of toxic reagents and solvents. Therefore, in the art of compatibilizers for thermally conductive formulations, it would be advantageous to find relatively low-cost FTAs with acceptable performance characteristics, including extrusion flow, extrusion rate, and viscosity.

The present invention solves the needs in the art by providing a composition comprising: a) polyorganosiloxane; b) filler particles; and c) filler treatment agent of formula I: I wherein m is 5 to 150; n is 1 to 3; p is 0 to 3; q is 0 to 8; each R ¹ is independently C ₁ -C ₆ -alkyl, vinyl, phenyl, or benzyl ; Each R ^{1 '} is independently C ₁ -C ₆ -alkyl; R ² is: wherein r is 0 to 5; s is 0 or 1; t is 0 to 15; each R ³ is independently C ₁ -C ₆ -alkyl; a is an integer from 1 to 3; wherein the polyorganosiloxane has Degree of polymerization in the range of 40 to 800.

The compositions of the present invention can be used as thermally conductive formulations.

The present invention is a composition, which includes: a) polyorganosiloxane; b) filler particles; and c) filler treatment agent of formula I: I wherein m is 5 to 150; n is 1 to 3; p is 0 to 3; q is 0 to 8; each R ¹ is independently C ₁ -C ₆ -alkyl, vinyl, phenyl, or benzyl ; Each R ^{1 '} is independently C ₁ -C ₆ -alkyl; R ² is: Where r is 0 to 5; s is 0 or 1; t is 0 to 15; each R ³ is independently C ₁ -C ₆ -alkyl; a is an integer from 1 to 3; and the dotted line represents the relationship with the alkylene group Point of attachment; wherein the polyorganosiloxane has a degree of polymerization in the range of 40 to 800.

FTA of Formula I is a random copolymer; that is, the structural units with subscripts m, n, and p need not be in the order depicted in Formula I. Preferably, m ranges from 20 or 50 to preferably 125; preferably, n ranges from 1 or 1.5 or 1.8 to 3 or to 2.5 or to 2.2; p ranges from 0 to 3 or to 2 or to 1 or to 0.5; q is 1 or 2 to 6 or to 4; each R ¹ is preferably independently C ₁ -C ₆ -alkyl, more preferably methyl or ethyl, and most preferably methyl; R ³ is preferably It is methyl or ethyl, more preferably methyl; a is preferably 2 or 3, more preferably 3.

In one aspect, R ² is represented by: where t is 0 or 1 or 2 or 3.

In another aspect, R ² is represented by: where q + t is in the range of 0 or 1 or 3 or 5 to 20 or to 14 or to 9.

The filler treatment agent of the present invention can be prepared by making a compound of formula Ia: where x is n + p; in contact with a compound of formula Ib: It is in the presence of a platinum catalyst and at high temperature to form a compound of formula I, wherein R ² is:

Filler treatment agents can also be prepared by making compounds of formula Ic: where x is n + p; in contact with a compound of formula Id: This is done in the presence of a platinum catalyst and at high temperature to form a compound of formula I, where s is 0 and y is 0 to 25.

Polyorganosiloxanes may be functionalized, for example, with one or more crosslinkable groups, such as terminal vinyl groups. Examples of such functionalized polyorganosiloxanes include monovinyl-di-C ₁ -C ₆ -alkyl terminated polysiloxanes and bis(vinyl-di-C ₁ -C ₆ -alkyl) End-capped polysiloxane, more specifically bis(vinyl-dimethyl) end-capped polysiloxane, which can be prepared as described in US 4,329,273.

Filler particles are metal, metal oxide, metal hydrate, or ceramic nitride particles, such as aluminum, aluminum oxide/alumina, aluminum trihydrate, boron nitride, or zinc oxide particles. The _D50 particle size of filler particles (as determined using a HELOS laser diffraction device) is generally in the range of 0.5 µm to 100 µm. Multimodal (eg, bimodal) distributions of first and second filler particles can be used in formulations to increase filler particle concentration.

Based on the weight of the composition, the polyorganosiloxane concentration is preferably in the range of 1.9 or 5 wt.% to 15 or 10 wt.%; based on the weight of the composition, the FTA concentration is preferably in the range of 0.1 or In the range of 0.2 or 0.3 wt.% to 3 or to 1 or to 0.7 or to 0.5 wt.%; and based on the weight of the composition, the filler loading is preferably 70 or 80 or 85 or 90 wt.% to Within the range of 98 or to 94 wt.%. The formulated compositions of the present invention have been found to have advantageous extrusion flow rates, viscosity, extrusion rates, and thermal conductivities. Example size exclusion chromatography method

SEC separations were performed on a liquid chromatograph with an Agilent 1260 Infinity II isocratic pump, multi-column thermostat, integrated degasser, autosampler, and refractive index detector. The system is equipped with two PLgel Mixed A columns (300 × 7.5 mm i.d., particle size = 20 µm) and a guard column (50 × 7.5 mm i.d.). The column oven and refractive index detector were operated at 40°C. The sample injection volume was 100 µL, and the separation was performed using THF as eluent at a flow rate of 1.0 mL/min. The instrument was calibrated using ten narrow dispersion polystyrene standards ranging from 580 to 371,000 Da. Data analysis was performed using Agilent GPC/SEC software suite version A.02.01 (Build 9.34851). NMR spectroscopy methods

NMR spectroscopy was performed using a Bruker Avance III HD 500 spectrometer (Billerica, MA) equipped with a 5-mm Prodigy BBO CryoProbe. Proton spectra were obtained with a pulse repetition delay of 10 s. Chemical shifts are expressed relative to the residual solvent protons of CDCl3 (δ ¹ H, 7.26 ppm). Example A – Preparation of Filler Treatment Agent

The copolymer of formula Ia' and the compound of formula Ib' are mixed at room temperature in a 1:1 molar ratio of vinyl groups to Si-H groups. Karstedt's catalyst (0.1 mol% based on vinyl) was added to the mixture and the temperature was raised to 120°C. After 2 h, the mixture was allowed to cool to room temperature, after which the reaction mixture was _diluted with CHCl and filtered through activated carbon/celite. Volatile materials in the polymer solution were removed, and the products were characterized by SEC and NMR. Example B – Preparation of Filler Treatment Agent

The copolymer of formula Ic' and the compound of formula Id' were mixed at room temperature in a 1:1 molar ratio of vinyl to Si-H groups, and the reaction, work-up, and characterization were as described in Example A conduct. Examples C, D, E – Preparation of Filler Treatment Agent

Compounds of Formula Ie' and Formula Ib' were mixed at room temperature in 3:1, 3:2, and 1:1 molar to molar ratios of vinyl to Si-H groups to prepare Examples C, D , and E. Examples 1 to 5 and Comparative Example 1 - Preparation of Formulations Containing FTA

The formulation was prepared by combining FTA (0.23 g) with DOWSIL ^™ 2-7287 vinyldimethyl-terminated polydimethylsiloxane (5.31 g, viscosity = 80 cP, The Dow Chemical Company or its subsidiary Company trademark) and DOWSIL ^™ CV-119 vinyldimethyl-terminated polydimethylsiloxane (1.79 g, viscosity = 450 cP) were combined in a Max-10 mixing cup and mixed at 2000 rpm 30 seconds. Next, this blend was combined with SB 36 alumina trihydrate (7.07 g, D ₅₀ = 25 µm) in a Max-40 mixing cup and mixed at 1300 rpm for 30 s. Maxfil MX200 alumina trihydrate (35.57 g, D ₅₀ = 45 µm) was added to the formula and mixed at 1300 rpm for 30 s. Next, the prepared materials were mixed manually, then mixed again at 1300 rpm for 30 s, then transferred to a glass jar and heated under vacuum at 150 °C for 1 h. The total filler loading of the material was 85.3 wt.% and 69.7 vol%. Measurement of extrusion flow

The squeeze flow test was used to characterize the flowability of test formulations containing FTA samples as follows: The thermal conductivity test formulation (0.6 g) was sandwiched between two glass slides (25 × 75 × 1.0 mm, obtained from Thermofisher) , and separated by two 1-mm spacers to control thickness. The top slide was manually pressed down to ensure even spread of material, and the initial diameter of the material was recorded as _D1 . Next, the 1-mm spacer was removed from the test sample, and a 350-g mass was placed on the top glass and allowed to sit for 1 min. The diameter after extrusion is recorded as D ₂ , and the extrusion flow rate is calculated as ΔR = (D ₂ – D ₁ )/2 (mm). Measurement of viscosity at 0.1% strain

Oscillatory shear strain amplitude scans were performed on test formulation samples to characterize formulation viscosity and shear thinning behavior. Test formulation samples were loaded onto an Anton Paar High Throughput Rheometer (AP HT Rheometer) using a 25-mm parallel plate geometry. Trimming is performed with a 1.0-mm gap by an automatic trimming robot. After a 300-s pre-test soak time, measurements were performed using a standard procedure with an oscillation frequency of 10 rad/s, scanning from 0.01 to 300% strain amplitude, with 20 sampling points per decade. Describe the viscosity at 0.1% strain (low shear rate viscosity). Measurement of extrusion rate

Extrusion rates were measured by filling gel formulations into 30-mL EFD syringes. Next, the syringe was attached to the EFD dispensing equipment and the material was dispensed under nitrogen at 55 Psi for 5 s. Extrusion rate was recorded as the mass dispensed during the 5-s dosing period, as determined using an analytical balance. Thermal conductivity measurement

Thermal conductivity was measured using a Hot Disk transient planar heat source tool (TPS 2500S) and a thermal probe in a Kapton package. Isotropic body measurements were performed on 6 mm diameter vessels.

Table 1 illustrates the extrusion flow rate (SF, in mm), viscosity at 0.1% strain (Visc., in Pa·s), and extrusion rate at 55 psi (ER, in g) of the thermogel samples. /5 s). RMS-759 refers to DOWSIL ^™ RMS-759 monotrimethoxysiloxy-dimethylsiloxane polymer (a trademark of The Dow Chemical Company or its subsidiaries), which is the FTA used in Comparative Example 1. Thermal conductivity of all formulations was measured at 2.3 W/m·K. Table 1 – Characteristics of thermal gel samples Ex# FTA SF Visc. ER C1 RMS-759 9.6 61.9 0.46 1 Ex. A 8.3 88.0 2.3 2 Ex.B 7.8 88.5 2.4 3 Ex.C 8.6 108.8 2.0 4 Ex. D 9.4 194.8 2.9 5 Ex.E 9.5 243.1 2.3

The formulations of Examples 1 to 5 all exhibited acceptable extrusion flow, viscosity at 0.1% strain, extrusion rate, and thermal conductivity. The extrusion rate is significantly improved compared to the commercial formulation (C1). The formulations of the present invention also benefit from the ease of preparing FTA.

without

without

Claims (10)

A composition comprising: a) polyorganosiloxane; b) filler particles; and c) filler treatment agent of formula I: I wherein m is 5 to 150; n is 1 to 3; p is 0 to 3; q is 0 to 8; each R ¹ is independently C ₁ -C ₆ -alkyl, vinyl, phenyl, or benzyl ; Each R ^{1 '} is independently C ₁ -C ₆ -alkyl; R ² is: wherein r is 0 to 5; s is 0 or 1; t is 0 to 15; each R ³ is independently C ₁ -C ₆ -alkyl; a is an integer from 1 to 3; wherein the polyorganosiloxane has Degree of polymerization in the range of 40 to 800. For example, the composition of claim 1, wherein the concentration of the polyorganosiloxane is in the range of 1.9 to 15 wt.%, and the concentration of the filler particles is in the range of 70 to 98 wt.% based on the weight of the composition. Within the range, and the concentration of the filler treatment agent of Formula I is within the range of 0.1 to 3 wt%; wherein the filler particles are aluminum, aluminum oxide, aluminum trihydrate, boron nitride, or zinc oxide particles. The composition of claim 2, wherein each R ¹ is independently C ₁ -C ₆ -alkyl; p is 0 to 2; q is 2 to 4; each R ¹ is independently C ₁ -C ₆ -alkyl ; and a is 0; wherein the filler particles are alumina particles with a concentration in the range of 85 to 94 wt% based on the weight of the composition. The composition of claim 3, wherein each R ¹ is independently methyl or ethyl; and p is 0 or 1. Such as the composition of claim 4, wherein each R ¹ is methyl; m is 50 to 125; n is 1.8 to 2.2; each R ³ is methyl; and p is 0 to 0.5; wherein the alumina filler particles are There is a bimodal distribution of the first alumina filler particles and the second alumina filler particles. Such as the composition of any one of claims 1 to 5, wherein n is 2, and R ² is represented by the following: where t is 0 or 1 or 2 or 3; and p is 0. The compound of claim 6, wherein t is 0; and each R ³ is methyl. Such as the composition of any one of claims 1 to 5, wherein n is 2, and R ² is represented by the following: where q + t ranges from 0 to 20; and p is 0. Such as the composition of claim 8, wherein q + t is in the range of 3 to 14. Such as the composition of claim 8, wherein q + t is in the range of 5 to 9.