阅读说明：本技术 包含无机颗粒的第一团聚体和第二团聚体的粉末组合物以及包含聚合物和该粉末组合物的聚合物组合物 (Powder composition comprising a first agglomerate and a second agglomerate of inorganic particles and polymer composition comprising a polymer and the powder composition ) 是由 克里斯托夫·莱斯尼亚克 罗伯托·M·舍德尔 克里希纳·B·乌贝尔 于 2018-12-18 设计创作，主要内容包括：本公开涉及一种包含无机颗粒的第一团聚体和第二团聚体的粉末组合物,涉及一种包含聚合物和所述粉末组合物的聚合物组合物,并且涉及一种由所述聚合物组合物制成的复合制品。本公开还涉及一种用于制备所述粉末组合物的方法和一种用于制备所述复合制品的方法,并且涉及所述粉末组合物作为热传导手段来控制电气和电子部件或组件或电池的温度的用途。本公开还涉及一种用于制备所述粉末组合物的部件套件。(The present disclosure relates to a powder composition comprising a first agglomerate and a second agglomerate of inorganic particles, to a polymer composition comprising a polymer and the powder composition, and to a composite article made from the polymer composition. The present disclosure also relates to a process for preparing the powder composition and a process for preparing the composite article, and to the use of the powder composition as a heat conducting means to control the temperature of an electrical and electronic component or assembly or battery. The present disclosure also relates to a kit of parts for preparing the powder composition.)

1. A powder composition comprising a first agglomerate of inorganic particles and a second agglomerate, wherein the encapsulation density of the first agglomerate is from 20% to 70% of the theoretical density of the inorganic particles of the first agglomerate, and wherein the encapsulation density of the second agglomerate is from 50% to 100% of the theoretical density of the inorganic particles of the second agglomerate, and wherein the encapsulation density of the second agglomerate is higher than the encapsulation density of the first agglomerate.

2. The powder composition of claim 1, wherein the first agglomerates have an encapsulation density that is 30% to 65% of the theoretical density of the inorganic particles of the first agglomerates, and wherein the second agglomerates have an encapsulation density that is 65% to 95% of the theoretical density of the inorganic particles of the second agglomerates.

3. The powder composition of claim 1 or 2, wherein the encapsulation density of the second agglomerates is at least 5% higher or at least 10% higher or at least 20% higher than the encapsulation density of the first agglomerates, based on the encapsulation density of the first agglomerates.

4. The powder composition according to any one of claims 1 to 3, wherein the inorganic particles of the first agglomerates and the second agglomerates are selected from boron nitride, aluminum oxide, aluminum nitride, silicon carbide, silicon nitride, magnesium oxide or mixtures thereof.

5. The powder composition according to any one of claims 1 to 4, wherein the inorganic particles of the first agglomerates and the second agglomerates comprise boron nitride, or wherein the inorganic particles of the first agglomerates and the second agglomerates comprise aluminum oxide, or wherein the inorganic particles of the first agglomerates and the second agglomerates comprise aluminum nitride, or wherein the inorganic particles of the first agglomerates and the second agglomerates comprise silicon carbide, or wherein the inorganic particles of the first agglomerates and the second agglomerates comprise silicon nitride, or wherein the inorganic particles of the first agglomerates and the second agglomerates comprise magnesium oxide.

6. The powder composition according to any one of claims 1 to 5, wherein the inorganic particles of the first agglomerates comprise at least 50 wt% boron nitride, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise at least 50 wt% boron nitride, based on the total weight of the second agglomerates,

or wherein the inorganic particles of the first agglomerates comprise at least 50 wt.% of alumina based on the total weight of the first agglomerates and the inorganic particles of the second agglomerates comprise at least 50 wt.% of alumina based on the total weight of the second agglomerates,

or wherein the inorganic particles of the first agglomerates comprise at least 50 wt% of aluminum nitride, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise at least 50 wt% of aluminum nitride, based on the total weight of the second agglomerates,

or wherein the inorganic particles of the first agglomerates comprise at least 50 wt% silicon carbide, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise at least 50 wt% silicon carbide, based on the total weight of the second agglomerates,

or wherein the inorganic particles of the first agglomerates comprise at least 50 wt% silicon nitride, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise at least 50 wt% silicon nitride, based on the total weight of the second agglomerates,

or wherein the inorganic particles of the first agglomerate comprise at least 50 wt.% magnesium oxide based on the total weight of the first agglomerate and the inorganic particles of the second agglomerate comprise at least 50 wt.% magnesium oxide based on the total weight of the second agglomerate.

7. According to claims 1 to6, wherein the inorganic particles of the first agglomerates comprise at least 50 wt% boron nitride based on the total weight of the first agglomerates, and wherein the inorganic particles of the second agglomerates comprise at least 50 wt% boron nitride based on the total weight of the second agglomerates, and wherein the amount of the first agglomerates is from 50 wt% to 95 wt% based on the total content of the first agglomerates and the second agglomerates, and wherein the amount of the second agglomerates is from 5 wt% to 50 wt% based on the total content of the first agglomerates and the second agglomerates, and wherein the average agglomerate size (d) of the first agglomerates₅₀) Is from 25 μm to 500 μm, and wherein the second agglomerates have an average agglomerate size (d)₅₀) From 25 to 500 μm, and wherein the encapsulation density of the first agglomerates is from 30 to 65% of the theoretical density of the inorganic particles of the first agglomerates, and the encapsulation density of the second agglomerates is from 65 to 95% of the theoretical density of the inorganic particles of the second agglomerates, and wherein the specific surface area of the first agglomerates is at most 30m²And wherein the specific surface area of the second agglomerates is at most 30m²/g。

8. The powder composition according to any one of claims 1 to 7, wherein the amount of the first agglomerates is up to 99 wt. -%, based on the total content of the first agglomerates and the second agglomerates, and wherein the amount of the second agglomerates is up to 99 wt. -%, based on the total content of the first agglomerates and the second agglomerates.

9. The powder composition according to any one of claims 1 to 8, wherein the first agglomerate or the second agglomerate of the inorganic particles does not have a spherical shape, or wherein the first agglomerate and the second agglomerate of the inorganic particles does not have a spherical shape.

10. A polymer composition comprising a polymer and the powder composition according to any one of claims 1 to 9.

11. A composite article made from the polymer composition of claim 10.

12. Kit of parts for preparing a powder composition according to any one of claims 1 to 9, wherein the kit of parts comprises a first part comprising a first agglomerate of inorganic particles in powder form and a second part comprising a second agglomerate of inorganic particles in powder form, wherein the encapsulation density of the first agglomerate is between 20% and 70% of the theoretical density of the inorganic particles of the first agglomerate, and wherein the encapsulation density of the second agglomerate is between 50% and 100% of the theoretical density of the inorganic particles of the second agglomerate, and wherein the encapsulation density of the second agglomerate is higher than the encapsulation density of the first agglomerate.

13. A process for preparing the powder composition according to any one of claims 1 to 9, the process comprising the steps of:

providing a first powder comprising a first agglomerate of inorganic particles and a second powder comprising a second agglomerate of inorganic particles, and

mixing the first powder and the second powder;

wherein the first agglomerates have an encapsulation density of 20% to 70% of the theoretical density of the inorganic particles of the first agglomerates, and wherein the second agglomerates have an encapsulation density of 50% to 100% of the theoretical density of the inorganic particles of the second agglomerates, and wherein the encapsulation density of the second agglomerates is higher than the encapsulation density of the first agglomerates.

14. A method for making the composite article of claim 11, the method comprising the steps of

Providing a powder composition according to any one of claims 1 to 9 and a polymer,

mixing the powder composition and the polymer to obtain a mixed composition,

placing the mixed composition in a mold, and

curing the mixed composition, thereby obtaining the composite article.

15. Use of the powder composition according to any one of claims 1 to 9 as a means of thermal conduction to control the temperature of an electrical and electronic component or assembly or battery.

Technical Field

The present disclosure relates to an agglomerate mixture of first and second agglomerates of inorganic particles, and to a composition comprising a polymer and the agglomerate mixture of first and second agglomerates of inorganic particles.

Background

The use of thermally conductive polymer compounds for thermal management solutions, such as in electronic devices in mobile devices, L ED technology, or electric vehicles, has increased demand for thermally conductive and electrically insulating polymer materials.

WO2008042446 discloses a boron nitride composition comprising at least two different types of boron nitride powder materials, such as spherical agglomerates of boron nitride and platelet boron nitride. When flake boron nitride having large flakes is added to spherical boron nitride, the viscosity of the silicone resin filled with boron nitride decreases.

There remains a need for filled polymeric materials having high thermal conductivity at low viscosity.

Disclosure of Invention

In a first aspect, the present disclosure relates to a powder composition comprising a first agglomerate and a second agglomerate of inorganic particles, wherein the encapsulation density of the first agglomerate is between 20% and 70% of the theoretical density of the inorganic particles of the first agglomerate, and wherein the encapsulation density of the second agglomerate is between 50% and 100% of the theoretical density of the inorganic particles of the second agglomerate, and wherein the encapsulation density of the second agglomerate is higher than the encapsulation density of the first agglomerate.

In another aspect, the present disclosure also relates to a polymer composition comprising a polymer and the powder composition disclosed herein.

In yet another aspect, the present disclosure relates to a composite article made from the polymer composition disclosed herein.

In yet another aspect, the present disclosure relates to a method for preparing the powder composition disclosed herein, the method comprising the steps of:

providing a first powder comprising a first agglomerate of inorganic particles and a second powder comprising a second agglomerate of inorganic particles,

mixing the first powder and the second powder;

wherein the first agglomerates have an encapsulation density of 20% to 70% of the theoretical density of the inorganic particles of the first agglomerates, and wherein the second agglomerates have an encapsulation density of 50% to 100% of the theoretical density of the inorganic particles of the second agglomerates, and wherein the encapsulation density of the second agglomerates is higher than the encapsulation density of the first agglomerates.

In yet another aspect, the present disclosure relates to a method for making the composite article disclosed herein, comprising the steps of:

providing the powder composition and polymer disclosed herein,

mixing the powder composition and the polymer to obtain a mixed composition,

placing the mixed composition in a mold, and

curing the mixed composition, thereby obtaining the composite article.

In a further aspect, the present disclosure relates to the use of the powder composition disclosed herein as a means of thermal conduction to control the temperature of an electrical and electronic component or assembly or battery.

In yet another aspect, the present disclosure relates to a kit of parts for preparing the powder composition disclosed herein, the kit of parts comprising a first part comprising a first agglomerate of inorganic particles in powder form and a second part comprising a second agglomerate of inorganic particles in powder form, wherein the first agglomerate has an encapsulation density of 20% to 70% of the theoretical density of the inorganic particles of the first agglomerate, and wherein the second agglomerate has an encapsulation density of 50% to 100% of the theoretical density of the inorganic particles of the second agglomerate, and wherein the second agglomerate has an encapsulation density higher than the encapsulation density of the first agglomerate.

In some embodiments, the viscosity of the polymer composition filled with the powder composition comprising first agglomerates and second agglomerates as disclosed herein is lower than would be expected from a linear relationship between the viscosity of a polymer composition filled with only first agglomerates and only second agglomerates. The thermal conductivity of the composite article filled with the powder composition comprising first agglomerates and second agglomerates as disclosed herein may be as expected from a linear relationship between the thermal conductivities of composite articles filled with only first agglomerates and only second agglomerates, and in some embodiments, the thermal conductivity may even exceed the value expected from the linear relationship.

In some embodiments, for the composite article made with the powder composition comprising first agglomerates and second agglomerates as disclosed herein, the filler loading of the thermally conductive filler may be higher than that obtainable with only the first agglomerates, and thus the thermal conductivity of the composite article made with the powder composition comprising first agglomerates and second agglomerates as disclosed herein may be higher than that obtainable with only the first agglomerates or second agglomerates.

In some embodiments, for the composite article made with the powder composition comprising first agglomerates and second agglomerates as disclosed herein, the thermal conductivity is as high as, or nearly as high as, the thermal conductivity of a composite article made with only first agglomerates, while the viscosity of the polymer composition used to make the composite article may be lower than, or significantly lower than, the viscosity of a polymer composition made with only first agglomerates.

Drawings

Fig. 1 is an intrusion pattern obtained by mercury intrusion.

Detailed Description

The powder compositions disclosed herein comprise first agglomerates and second agglomerates of inorganic particles, wherein the encapsulation density of the first agglomerates is from 20% to 70% of the theoretical density of the inorganic particles of the first agglomerates, and wherein the encapsulation density of the second agglomerates is from 50% to 100% of the theoretical density of the inorganic particles of the second agglomerates. The encapsulation density of the second agglomerates is higher than the encapsulation density of the first agglomerates.

Hereinafter, the first agglomerates are also referred to as low density agglomerates, and the second agglomerates are also referred to as high density agglomerates.

In some embodiments, the encapsulation density of the first agglomerates of the powder compositions disclosed herein is from 30% to 65% of the theoretical density of the inorganic particles of the first agglomerates, and the encapsulation density of the second agglomerates is from 65% to 95% of the theoretical density of the inorganic particles of the second agglomerates.

In some embodiments, the encapsulation density of the second agglomerates of the powder compositions disclosed herein is at least 5% higher or at least 10% higher or at least 20% higher than the encapsulation density of the first agglomerates, based on the encapsulation density of the first agglomerates.

In some embodiments, the powder compositions disclosed herein consist of a first agglomerate and a second agglomerate of inorganic particles, wherein the encapsulation density of the first agglomerate is from 20% to 70% of the theoretical density of the inorganic particles of the first agglomerate, and wherein the encapsulation density of the second agglomerate is from 50% to 100% of the theoretical density of the inorganic particles of the second agglomerate. The encapsulation density of the second agglomerates is higher than the encapsulation density of the first agglomerates.

The envelope density of the agglomerates is defined by the ratio of the mass of the agglomerates to the sum of the volumes of the solids in each agglomerate and the voids within each agglomerate that are located within a tightly fitting hypothetical envelope that completely surrounds each agglomerate. The packing density is determined by the volume of the solid material, the open pores and the closed pores. The volume of the inter-agglomerate voids, i.e., the volume of the voids between agglomerates, is not a part of the encapsulated volume. In contrast, the total volume is the envelope volume of the agglomerates plus the volume of the interstitial spaces between the agglomerates. The envelope density is the mass of the agglomerates divided by the volume of the agglomerates within the hypothetical, closely fitting skin that encapsulates each agglomerate, and thus may contain a small volume of surface irregularities.

The envelope density is measured by mercury intrusion. The measurement can be carried out according to ISO15901-1 (2016-04-01). The volume of the inter-agglomerate voids was subtracted from the total volume to give the envelope volume. The envelope density is determined from the mass and envelope volume of the sample used for mercury intrusion measurements. The total volume was measured by mercury intrusion according to ISO15901-1 (2016-04-01). The volume of the inter-agglomerate voids is determined from an intrusion map obtained by mercury intrusion, wherein the first mathematical derivation of the map reaches a minimum after filling the agglomerate voids, i.e. after filling the inter-agglomerate voids.

Since the encapsulation density of the first agglomerates is lower than the encapsulation density of the second agglomerates, the first agglomerates are more porous than the second agglomerates.

The inorganic particles of the first agglomerates and the second agglomerates may be selected from boron nitride, alumina, aluminum nitride, silicon carbide, silicon nitride, magnesium oxide, or mixtures thereof.

The theoretical density of the inorganic particles is the density of the inorganic particles without defects. For boron nitride, the theoretical density of the inorganic particles is 2.27g/cm³. For alumina, the theoretical density of the inorganic particles is 3.95g/cm³. For aluminum nitride, the theoretical density of the inorganic particles is 3.26g/cm³. For silicon carbide, the theoretical density of the inorganic particles is 3.21g/cm³. For silicon nitride, the theoretical density of the inorganic particles is 3.44g/cm³. For magnesium oxide, the theoretical density of the inorganic particles is 3.58g/cm³。

In some embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerate and the second agglomerate comprise boron nitride. Preferably, the inorganic particles of the first agglomerates of these embodiments comprise at least 50 wt% boron nitride, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates preferably comprise at least 50 wt% boron nitride, based on the total weight of the second agglomerates.

In some other embodiments, the inorganic particles of the first agglomerates comprise at least 90 wt% boron nitride based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise at least 90 wt% boron nitride based on the total weight of the second agglomerates. The first agglomerate of these embodiments may have an encapsulation density of 0.5 to 1.6g/cm³And the second agglomerates may have an encapsulation density of 1.1 to 2.27g/cm³Or the first agglomerate may have an encapsulation density of 0.7 to 1.5g/cm³And the second agglomerates may have an encapsulation density of 1.5 to 2.2g/cm³。

In some other embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerates and the second agglomerates comprise alumina. Preferably, the inorganic particles of the first agglomerates of these embodiments comprise at least 50 wt% alumina, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates preferably comprise at least 50 wt% alumina, based on the total weight of the second agglomerates.

In some other embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerate and the second agglomerate comprise aluminum nitride. Preferably, the inorganic particles of the first agglomerate of these embodiments comprise at least 50 wt% aluminum nitride, based on the total weight of the first agglomerate, and the inorganic particles of the second agglomerate preferably comprise at least 50 wt% aluminum nitride, based on the total weight of the second agglomerate.

In some other embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerates and the second agglomerates comprise silicon carbide. Preferably, the inorganic particles of the first agglomerates of these embodiments comprise at least 50 wt% silicon carbide, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates preferably comprise at least 50 wt% silicon carbide, based on the total weight of the second agglomerates.

In some other embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerates and the second agglomerates comprise silicon nitride. Preferably, the inorganic particles of the first agglomerates of these embodiments comprise at least 50 wt% silicon nitride, based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates preferably comprise at least 50 wt% silicon nitride, based on the total weight of the second agglomerates.

In some other embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerate and the second agglomerate comprise magnesium oxide. Preferably, the inorganic particles of the first agglomerate of these embodiments comprise at least 50 wt.% magnesium oxide, based on the total weight of the first agglomerate, and the inorganic particles of the second agglomerate preferably comprise at least 50 wt.% magnesium oxide, based on the total weight of the second agglomerate.

Average agglomerate size (d) of first agglomerates and second agglomerates₅₀) May be 1 μm to 5 mm. In some embodiments, the average agglomerate size (d)₅₀) Is 25 to 500 μmOr 50 to 500 μm, or 70 to 250 μm. Average agglomerate size (d)₅₀) D of up to 2mm can be measured by laser diffraction (wet method measurement)₅₀. For average agglomerate sizes (d) greater than 2mm₅₀) The measurement can be performed using a sieve tower (sieve stack).

The specific surface area (BET) of the first agglomerates is higher than the specific surface area of the second agglomerates.

The first agglomerates and the second agglomerates may be spherical, flake-like or scaly in fibrous form or irregular shape.

The first agglomerates and the second agglomerates may have isotropic or anisotropic properties.

For embodiments of the powder composition having inorganic particles comprising first and second agglomerates of boron nitride, the specific surface area (BET) of the first and second agglomerates may be up to 30m²Per g, or up to 20m²Per g, or up to 15m²/g。

The oxygen content of the first agglomerates and the second agglomerates consisting essentially of boron nitride may be up to 5 wt.%, or up to 1 wt.%, or up to 0.5 wt.%, or up to 0.1 wt.%.

The inorganic particles of the first agglomerate and the second agglomerate may also be referred to as grains or primary particles. The first agglomerates and the second agglomerates of the powder compositions disclosed herein may comprise at least 2, or at least 5, or at least 10, or at least 15, or at least 20 primary particles. The primary particles can be observed as individual particles by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), or by polished cross-sections of composite articles made with the powder compositions and polymers disclosed herein.

Average particle size (d) of the primary particles₅₀) Can be 0.2 μm to 100 μm. Average particle size (d) of the primary particles₅₀) Can be measured by laser diffraction (wet measurement).

The boron nitride primary particles may be platelet-shaped.

The primary particles of the first agglomerate and the second agglomerate may have a preferred orientation in the agglomerates, or may be randomly oriented in the agglomerates.

In the powder compositions disclosed herein, the amount of the first agglomerates may be up to 99 wt% based on the total content of the first agglomerates and the second agglomerates, and the amount of the second agglomerates may be up to 99 wt% based on the total content of the first agglomerates and the second agglomerates. In some embodiments, the amount of the first agglomerates may be up to 95 wt% based on the total content of the first agglomerates and the second agglomerates, and the amount of the second agglomerates may be up to 95 wt% based on the total content of the first agglomerates and the second agglomerates. In some embodiments, the amount of the first agglomerates may be up to 90 wt% based on the total content of the first agglomerates and the second agglomerates, and the amount of the second agglomerates may be up to 90 wt% based on the total content of the first agglomerates and the second agglomerates.

In some embodiments, the amount of the first agglomerates may be at least 20 wt.%, or at least 50 wt.%, or at least 60 wt.%, or at least 70 wt.%, based on the total content of the first agglomerates and the second agglomerates. Correspondingly, the amount of second agglomerates may be up to 30 wt%, or up to 40 wt%, or up to 50 wt%, or up to 80 wt%, based on the total content of first agglomerates and second agglomerates.

In some embodiments, the amount of the first agglomerates may be from 10 wt% to 95 wt%, or from 25 wt% to 95 wt%, or from 50 wt% to 95 wt%, or from 75 wt% to 95 wt%, based on the total content of the first agglomerates and the second agglomerates, and the amount of the second agglomerates may be from 5 wt% to 90 wt%, or from 5 wt% to 75 wt%, or from 5 wt% to 50 wt%, or from 5 wt% to 25 wt%, based on the total content of the first agglomerates and the second agglomerates.

In some embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerates comprise boron nitride in an amount of at least 50 wt% based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise boron nitride in an amount of at least 50 wt% based on the total weight of the second agglomerates, and the second agglomerates comprise boron nitride in an amount of at least 50 wt% based on the total content of the first agglomerates and the second agglomeratesThe amount of the first agglomerates is from 50 to 95 wt% and the amount of the second agglomerates is from 5 to 50 wt% based on the total content of the first agglomerates and the second agglomerates, and the average agglomerate size (d) of the first agglomerates₅₀) Is 25 μm to 500 μm, and the average agglomerate size (d) of the second agglomerates₅₀) Is 25 to 500 [ mu ] m and the encapsulation density of the first agglomerates is 30 to 65% of the theoretical density of the inorganic particles of the first agglomerates and the encapsulation density of the second agglomerates is 65 to 95% of the theoretical density of the inorganic particles of the second agglomerates and the specific surface area of the first agglomerates is at most 30m²Per g and the specific surface area of the second agglomerates is at most 30m²/g。

In some embodiments of the powder compositions disclosed herein, the inorganic particles of the first agglomerates comprise boron nitride in an amount of at least 50 wt% based on the total weight of the first agglomerates, and the inorganic particles of the second agglomerates comprise boron nitride in an amount of at least 50 wt% based on the total weight of the second agglomerates, and the amount of the first agglomerates is from 50 wt% to 95 wt% based on the total content of the first agglomerates and the second agglomerates, and the amount of the second agglomerates is from 5 wt% to 50 wt% based on the total content of the first agglomerates and the second agglomerates, and the average agglomerate size (d) of the first agglomerates₅₀) Is 25 μm to 500 μm, and the average agglomerate size (d) of the second agglomerates₅₀) Is 25 to 500 [ mu ] m and the encapsulation density of the first agglomerates is 30 to 65% of the theoretical density of the inorganic particles of the first agglomerates and the encapsulation density of the second agglomerates is 65 to 95% of the theoretical density of the inorganic particles of the second agglomerates and the specific surface area of the first agglomerates is at most 30m²Per g and the specific surface area of the second agglomerates is at most 30m²And the first agglomerates and the second agglomerates are platelet-shaped.

In some embodiments of the powder compositions disclosed herein, the first agglomerate or the second agglomerate of inorganic particles does not have a spherical shape. In some other embodiments of the powder compositions disclosed herein, neither the first agglomerate nor the second agglomerate of inorganic particles have a spherical shape.

The powder compositions disclosed herein may also comprise inorganic particles in non-agglomerated form.

The powder compositions disclosed herein may have a metal content in elemental form of at most 5 wt.%, or at most 1 wt.%, or at most 0.1 wt.%, based on the total amount of the powder composition. The powder compositions disclosed herein may have a graphite content of at most 5 wt%, or at most 1 wt%, or at most 0.3 wt%, based on the total amount of the powder composition.

The first agglomerates and second agglomerates used herein may be prepared by methods known in the art, such as spray drying for preparing spherical agglomerates, or other methods such as bulk granulation. The first agglomerates and the second agglomerates comprising boron nitride may also be prepared by cold pressing and crushing, or by cold pressing, sintering and crushing, or by cold pressing, crushing and sintering. The pressing step may be repeated prior to sintering. The first agglomerates and the second agglomerates comprising boron nitride may also be prepared by hot pressing and milling. The first agglomerates and the second agglomerates comprising boron nitride can also be prepared by continuously feeding a uniform amount of boron nitride powder into the space between two counter-rotating rollers, thereby obtaining boron nitride agglomerates in the form of platelets. Such a process is described in US2012/0114905a 1.

To prepare the first agglomerates and second agglomerates used herein, a sintering step may also be performed. The sintering step may be performed at a temperature of 1200 ℃ to 2200 ℃ in an atmosphere comprising nitrogen for the first agglomerates and the second agglomerates comprising boron nitride, or 1700 ℃ to 2200 ℃ in an inert atmosphere or vacuum for the first agglomerates and the second agglomerates comprising silicon carbide.

After its preparation, the first agglomerate and the second agglomerate may be further processed. For example, one or more of the following possible treatments may be performed:

-steam treatment

Surface modification with silanes, titanates or other organometallic compounds at room temperature or under the influence of temperature and with a carrier or reaction gas.

Surface modification with polymers, for example with polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), copolymers, acrylates, oils or carboxylic acids.

By sol-gel systems, e.g. by boehmite sol or SiO₂Sol or infiltrated with water-insoluble glass or nanoparticles or surface-modified nanoparticles or mixtures thereof.

-infiltrating with a water-soluble or ethanol-soluble polymer. The boron nitride agglomerates may be infiltrated with a resin, such as, for example, a silicone resin, an epoxy resin, or a polyurethane resin, and the resin may be hardened with a hardener, or temperature hardened, prior to or during compounding.

Also disclosed herein is a polymer composition comprising a polymer and the powder composition disclosed herein. Suitable polymers are casting resins, thermoplastic polymers, thermoplastically processable hard-plastic polymers, thermoplastic elastomers, silicones, epoxy resins, polyurethanes, phenolic resins and melamine resins. One-component or two-component resins may be used.

The polymer composition can comprise 20 to 95 volume percent of the polymer and 5 to 80 volume percent of the powder composition disclosed herein, based on the total volume of the polymer composition. In some embodiments, the polymer composition can comprise 40 to 95 volume percent polymer and 5 to 60 volume percent of the powder composition disclosed herein, based on the total volume of the polymer composition. In some embodiments, the polymer composition comprises 40 to 95 volume percent of the polymer and 5 to 60 volume percent of the powder composition, based on the total volume of the polymer composition, and the inorganic particles of the first agglomerate of the powder composition comprise at least 50 weight percent of the boron nitride, based on the total weight of the first agglomerate, and the inorganic particles of the second agglomerate comprise at least 50 weight percent of the boron nitride, based on the total weight of the second agglomerate.

The polymer compositions disclosed herein may have a metal content in elemental form of at most 5 wt.%, or at most 1 wt.%, or at most 0.1 wt.%, based on the total amount of the polymer composition. The polymer compositions disclosed herein may have a graphite content of at most 5 wt.%, or at most 1 wt.%, or at most 0.3 wt.%, based on the total amount of the polymer composition.

In addition to the powder compositions disclosed herein, the polymer compositions disclosed herein may also contain other inorganic filler materials, such as oxides, hydroxides, carbides, nitrides, minerals, and combinations thereof. The oxides, hydroxides, nitrides and carbides may be selected from the group consisting of alumina, magnesia, aluminum nitride, aluminum hydroxide, aluminum oxyhydroxide, silica, silicon carbide, silicon nitride and mixtures thereof. The mineral filler used may be selected from aluminosilicate, magnesium silicate (2MgO SiO)₂) Magnesium aluminate (MgO. about. Al)₂O₃) Brucite (magnesium hydroxide, Mg (OH)₂) Quartz, cristobalite, phyllosilicates such as talc and mixtures thereof. The aluminosilicate or alumino-silicate used may be, for example, kyanite (Al)₂SiO₅) And/or mullite (3 Al)₂O₃*2SiO₂)。

Also disclosed herein is a composite article made from the polymer composition disclosed herein.

The composite article may have a thermal conductivity of at least 1W/m K. The thermal conductivity of the composite article is understood to be the bulk thermal conductivity.

The composite article may be an adhesive article or a non-adhesive article.

The composite article may be a solid or a paste. For pastes, for example, silicone oils or fluorinated oils can be used as polymers.

The polishing portion can be prepared from a solid form of the composite article to determine the porosity of the different agglomerates, i.e., the porosity of the first agglomerate and the second agglomerate in the composite article. The porosity of the individual agglomerates can be determined by image analysis of the area of pores within the agglomerates in the polished section. The image analysis may be performed on a micrograph of the polished portion taken by an optical microscope, a scanning electron microscope, or a transmission electron microscope. The area percentage of pores corresponds to the porosity of the individual agglomerates, expressed as a volume percentage. The porosity, expressed as a volume percentage, corresponds to the envelope density, expressed as the theoretical density of the inorganic particles of the agglomerate.

Also disclosed herein is a kit of parts for preparing the powder composition disclosed herein. The kit of parts includes a first component comprising a first agglomerate of inorganic particles in powder form and a second component comprising a second agglomerate of inorganic particles in powder form. The encapsulation density of the first agglomerates is 20% to 70% of the theoretical density of the inorganic particles of the first agglomerates, and the encapsulation density of the second agglomerates is 50% to 100% of the theoretical density of the inorganic particles of the second agglomerates. The encapsulation density of the second agglomerates is higher than the encapsulation density of the first agglomerates.

The powder compositions disclosed herein may be prepared according to a process comprising the steps of:

providing a first powder comprising a first agglomerate of inorganic particles and a second powder comprising a second agglomerate of inorganic particles, and

mixing the first powder and the second powder;

wherein the first agglomerates have an encapsulation density of 20% to 70% of the theoretical density of the inorganic particles of the first agglomerates, and wherein the second agglomerates have an encapsulation density of 50% to 100% of the theoretical density of the inorganic particles of the second agglomerates, and wherein the encapsulation density of the second agglomerates is higher than the encapsulation density of the first agglomerates.

The step of mixing the first and second powders may be performed in standard mixing units known in the art, such as a can roll, Eirich mixer, V-blender, or a drum and hoop mixer.

The composite articles disclosed herein can be prepared according to a process comprising the steps of:

providing the powder compositions and polymers disclosed herein,

mixing the powder composition and the polymer to obtain a mixed composition,

placing the mixed composition in a mold, and

curing the mixed composition, thereby obtaining the composite article.

The mixing step of the powder composition and the polymer can be carried out by standard mixing units known in the art, such as mixing drums, V-blenders, drum hoop mixers, vibratory ball mills or Eirich mixers, or by extrusion using standard compounding units known in the art, such as single screw extruders, twin screw extruders, tangential or close intermeshing, co-or counter rotating, planetary roll extruders, slotted barrel extruders, pin extruders, calendering, Buss co-kneaders, shear roll extruders, injection molding machines and stirred tanks.

If the step of placing the mixed composition in a mold and curing is performed by casting, the mold may also be a device from which the molded and cured article is not demolded, such as a housing, or a space between a transformer and its housing.

The powder compositions disclosed herein can be used as a means of thermal conduction to control the temperature of electrical and electronic components or assemblies or batteries, such as in mobile devices, L ED technology, or electric vehicles.