Thermal grease composition
A composition with specific filler particles and ether-functionalized trialkoxysilanes addresses the challenge of increasing thermal conductivity without raising viscosity, enhancing thermal grease performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-02-19
- Publication Date
- 2026-03-11
AI Technical Summary
Existing thermal greases face a challenge in achieving higher thermal conductivity without increasing viscosity, which affects printability and handling properties.
A composition comprising specific filler particles and treating agents, including ether-functionalized trialkoxysilanes, is used to enhance thermal conductivity while maintaining low viscosity.
The composition achieves high thermal conductivity with reduced viscosity, enabling better processability and performance in thermal interface materials.
Smart Images
Figure 2026508499000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to non-curing thermal grease compositions containing ether-functionalized trialkoxysilanes. [Background technology]
[0002] Non-curing thermal greases are widely used as thermal interface materials for transferring heat from heat-generating electronic components to heat sinks. Useful thermal greases are characterized by high bulk thermal conductivity, low thermal resistance, thin bondline thickness, and good flow and re-handling properties. Thermal greases typically contain over 90% by weight of a combination of thermally conductive fillers, such as zinc oxide, alumina, aluminum, boron nitride, and aluminum nitride, dispersed in a silicone-based fluid. Rapid increases in the power and power density of electronic components result in greater heat generation, necessitating higher thermal conductivity for thermal greases.
[0003] Thermal conductivity can be increased by increasing the loading of thermally conductive filler used in the formulation of the thermal grease. Unfortunately, however, higher filler loadings result in higher thermal grease viscosity, which reduces important properties such as printability and handling. To address this issue, U.S. Patent Application Publication No. 2008 / 0213578(A1) (Endo) discloses a thermal grease composition containing, inter alia, a trialkylsilyl-trialkoxysilyl-terminated polysiloxane (component B, paragraph
[0034] ) and an alkoxysilane (component C, paragraph
[0035] ). The inclusion of component C provides a lower viscosity and thus improved thermal grease flow compared to greases that do not contain this component.
[0004] There remains a need to achieve even lower thermal grease viscosities, and therefore it would be an advance in the non-hardening thermal grease art to find a thermal grease that can achieve higher thermal conductivity without a concomitant increase in viscosity. Summary of the Invention
[0005] The present invention provides a composition comprising, based on the weight of the composition, a) 80 to 95 wt. % of one or more filler particles selected from the group consisting of aluminum, alumina, silicon, silicon dioxide, magnesium oxide, aluminum nitride, graphite, silicon carbide, and zinc oxide; and b) 0.2 to 10 wt. % of a first treating agent of Formula 1:
[0006] [ka] In the formula, R and R 1’ are each independently C1-C6 alkyl, Y is O or CH2-CH2, and x is 20 to 200; and c) 0.05 to 2 wt. % of a second treatment agent of Formula 2:
[0007] [ka] In the formula, R 2 is C1~C 10 -alkyl, and each R 3 is independently C1-C6-alkyl, y is 0-8, and z is 1-10; and and d) up to 8 wt. % boron nitride platelet particles.
[0008] The compositions of the present invention are useful as non-hardening thermal greases. DETAILED DESCRIPTION OF THE INVENTION
[0009] The present invention provides a composition comprising, based on the weight of the composition, a) 80 to 95 wt. % of one or more filler particles selected from the group consisting of aluminum, alumina, silicon, silicon dioxide, magnesium oxide, aluminum nitride, silicon carbide, graphite, and zinc oxide; and b) 0.2 to 10 wt. % of a first treating agent of Formula 1:
[0010] [ka] In the formula, R and R 1’ are each independently C1-C6 alkyl, Y is O or CH2-CH2, and x is 20 to 200; and c) 0.05 to 2 wt. % of a second treatment agent of Formula 2:
[0011] [ka] In the formula, R 2 is C1~C 10 -alkyl, and each R 3 is independently C1-C6-alkyl, y is 0-8, and z is 1-10; and d) up to 8 wt. % boron nitride platelet particles.
[0012] The composition preferably comprises aluminum and zinc oxide filler particles in a combined concentration ranging from 85% or 90% to 95% by weight based on the weight of the composition. The concentration of aluminum particles is preferably within the range of 65%, or 68%, or 70% to 80%, or 78%, or 75% by weight of the composition. The aluminum particles advantageously have a diameter of: a) 0.5 μm or 1 μm to 5 μm or 3 μm; 50 and b) smaller particles having a volume average particle size D ranging from 7 μm to 20 μm, or 15 μm, or 12 μm. 50 The distribution is bimodal with larger particles having a volume average particle size.
[0013] The concentration of ZnO particles is preferably in the range of 10% or 15% to 25% or 20% by weight based on the weight of the composition. The ZnO particles preferably have a diameter D ranging from 50 nm or 80 nm to 500 nm or 200 nm or 150 nm. 50 The volume average particle size of aluminum, zinc oxide, and alumina particles is 50 and D 99 The volume average particle size is the D measured using laser refractometry. 50 Refers to the volume average particle size.
[0014] The concentration of the first treatment agent of Formula 1 is in the range of 0.2 wt.%, or 1 wt.%, or 3 wt.% to 8 wt.% based on the weight of the composition. 1 are each preferably methyl, more preferably methyl; and x is within the range of 20 to 200, or up to 150, or up to 100, or up to 50.
[0015] The concentration of the second treatment agent of Formula 2 is in the range of 0.05% or 0.1% to 2%, or 1%, or 0.5% by weight based on the weight of the composition. 2 and R 3 are each independently ethyl or methyl, preferably methyl; y is 0 to 8 or 6 or 5; and z is 1 to 10 or 8 or 6.
[0016] The composition optionally includes boron nitride platelet particles that increase thermal conductivity at the expense of viscosity. The platelet particles preferably have a thickness in the range of 750 nm to 5 μm as measured by scanning electron microscopy (SEM) and a D of preferably in the range of 3 μm to 40 μm as measured by dynamic light scattering. 50The boron nitride platelet particles preferably have a diameter-to-thickness aspect ratio in the range of 2:1, or 3:1, or 4:1 to 50:1, or 30:1, or 20:1, or 10:1. The boron nitride platelet particles have a hexagonal crystal structure. During assembly, the boron nitride platelet particles align along approximately the same direction as the substrates after the platelet particles are applied between the substrates. Therefore, the D of the boron nitride platelet particles 50 Particle size does not affect the final bondline thickness. Commercially available examples of boron nitride platelet particles include CarboTherm PCTP30 boron nitride from St. Gobain and PolarTherm PT110 from Momentive Performance Materials. The concentration of the boron nitride platelet particles ranges from 0 wt%, or 0.5 wt%, or 1 wt%, or 2 wt%, to 8 wt%, or 6 wt%, or 5 wt%, or 4 wt%, based on the weight of the composition.
[0017] The compositions of the present invention provide non-hardening greases that are capable of achieving high thermal conductivity at dispensable and processable viscosities. [Example]
[0018] In the following examples, pbw refers to parts by weight. All mixing was performed using a Flacktek Speedmixer at 1500 rpm unless otherwise noted.
[0019] General procedure for preparation of thermally conductive materials A first filler treating agent (TA1, 6.01 pbw, each of R and R 1=CH3, R = O, and x = 30 (prepared as described in U.S. Patent Application Publication No. 2006 / 0100336), second filler treatment (TA-2 through TA-6, 0.2 pbw), Zoco 102 ZnO particles (ZnO-1, 11.76 pbw, 0.12 μm), and Zoco 104 ZnO particles (ZnO-2, 5.88 pbw, 0.20 μm) were added to a MAX100 cup and mixed for 15 seconds. Then, first aluminum particles (Al-1, 24.38 pbw, 2.0 μm, equivalent to TCP-2 Al powder) were added to the mixer and the contents were mixed for 15 seconds. Then, TCP-9 Al powder (Al-2, 48.77 pbw, 9.9 μm) was added to the mixer and mixing continued for 40 seconds. The mixture was then mixed by hand using a spatula and then further mixed in the mixer for 40 seconds. Boron nitride (BN, 3 pbw) was then added to the mixer and mixing continued for 15 seconds. The compounded composition was transferred to an aluminum pan and heated at 150°C under vacuum (23 torr) for 1 hour.
[0020] Table 1 summarizes the materials and amounts used to prepare the examples and comparative examples. TA-2, TA-3, TA-4, TA-5, and TA-6 have the following structures:
[0021] [ka]
[0022] [Table 1]
[0023] Viscosity measurement The complex viscosity (Pa·s) at the dilatant point was measured according to ASTM D4440-15 (Standard Test Method for Plastics: Dynamic Mechanical Properties Melt Rheology) using a TA Instruments ARES-G2 instrument with 25 mm parallel plates (serrated steel). Test conditions were based on a strain sweep performed at 25°C with a 2.0 mm gap. Measurements were performed using standard procedures with an oscillation frequency of 10 rad / s and a strain amplitude sweep from 0.01 to 200% with 20 sampling points every 10 seconds. The dilatant point was defined as the strain at which the complex viscosity began to increase.
[0024] Table 2 summarizes the viscosity at the dilatant point of the samples (column Viscosity) in Pa·s.
[0025] [Table 2]
[0026] The data show a significant reduction in viscosity for samples prepared with the ether-functionalized trimethoxysilane filler treatment relative to samples prepared with alkyltrimethoxysilane. Lower viscosity formulations provide a path for formulators to optimize viscosity and thermal conductivity. For example, when the formulation of Example 2 was modified to increase the BN concentration to 5 pbw and decrease the Al-2 concentration to 46.77 pbw, the thermal conductivity was measured to be 7.9 W / m·K, and the viscosity was found to increase to 68 Pa·s. In contrast, the thermal conductivity of Comparative Example 1 was measured to be 7.9 W / m·K, but had a viscosity of 89 Pa·s.
Claims
1. 1. A composition comprising, based on the weight of the composition, a) 80 to 95 wt. % of one or more filler particles selected from the group consisting of aluminum, alumina, silicon, silicon dioxide, magnesium oxide, aluminum nitride, silicon carbide, graphite, and zinc oxide; and b) 0.2 to 10 wt. % of a first treating agent of Formula 1: 【Chemistry 1】 In the formula, R and R １’ are each independently C １ ~C ６ -alkyl and Y is O or CH ２ -CH ２ and x is 20 to 200; and c) 0.05 to 2 wt. % of a second treating agent of Formula 2: 【Chemistry 2】 In the formula, R ２ is C １ ~C １０ -alkyl, and each R ３ are independently １ ~C ６ -alkyl, y is 0 to 8, and z is 1 to 10; and d) up to 8 wt. % boron nitride platelet particles.
2. The composition of claim 1 , wherein the filler particles are selected from the group consisting of aluminum, alumina, and zinc oxide.
3. 3. The composition of claim 2, comprising: a) aluminum and zinc oxide filler particles in a combined concentration ranging from 85 to 95 wt. %, based on the weight of the composition; and b) boron nitride platelet particles in a concentration ranging from 0.5 to 8 wt. %, based on the weight of the composition.
4. Y is O, x is 20 to 100, y is 0 to 6, z is 1 to 8, R, R １ , R ２ , and R ３ The composition of claim 3 , wherein each is methyl.
5. 3. The composition of claim 2, wherein the concentration of the first treatment agent of Formula 1 is in the range of 1 to 8 wt %, based on the weight of the composition, and the concentration of the second treatment agent of Formula 2 is in the range of 0.1 to 1 wt %, based on the weight of the composition.
6. a concentration of aluminum particles in the range of 65 to 80 wt. % based on the weight of the composition, a concentration of zinc oxide particles in the range of 10 to 25 wt. % based on the weight of the composition, and the aluminum particles have a D ５０ and b) smaller particles having a volume average particle size D in the range of 7 μm to 20 μm. ５０ and larger particles having a volume average particle size D in the range of 50 nm to 200 nm. ５０ The composition of claim 3 having a volume average particle size.
7. a concentration of aluminum particles in the range of 70 to 78 wt. % based on the weight of the composition, a concentration of zinc oxide particles in the range of 15 to 20 wt. % based on the weight of the composition, and the aluminum particles have a D ５０ and b) smaller particles having a volume average particle size D in the range of 7 μm to 15 μm. ５０ and larger particles having a volume average particle size D in the range of 80 nm to 150 nm. ５０ 6. The composition of claim 5, wherein the concentration of the first treatment agent of Formula 1 is in the range of 3 to 8 wt. %, and x is in the range of 20 to 50.
8. The second treating agent of Formula 2 is: 【Transformation 3】 and the concentration of the second treatment agent of Formula 2 is in the range of 0.1 to 0.5 wt %, based on the weight of the composition.