Patent Description:
The present application relates to a composite material.

Heat-dissipating materials can be used in various applications. For example, since batteries and various electronic apparatuses generate heat during operation, a material capable of effectively controlling such heat is required.

As materials having good heat dissipation properties, ceramic materials having good thermal conductivity and the like are known, but since such materials have poor processability, a composite material produced by blending the ceramic filler or the like exhibiting high thermal conductivity in a polymer matrix can be used.

However, since a large amount of filler components must be applied in order to secure high thermal conductivity by the above method, various problems arise. For example, in the case of a material containing a large amount of filler components, the material itself tends to become hard, and in such a case, impact resistance or the like is deteriorated.

The present application relates to a composite material and in one example, it is intended to provide a composite material ensuring other excellent physical properties such as impact resistance and processability while having excellent thermal conductivity, or a method for producing the same.

The present application relates to a composite material. In the present application, the term composite material may mean a material comprising a metal foam and a polymer component.

In this specification, the term metal foam or metal skeleton means a porous structure comprising a metal or a metal alloy as a main component. Here, the fact that a metal or the like uses as a main component means that the ratio of the metal or the like is <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, or <NUM> weight% or more based on the total weight of the metal foam or the metal skeleton. The upper limit of the ratio of the metal or the like contained as the main component is not particularly limited, and for example, may be <NUM> weight%, <NUM> weight% or <NUM> weight% or so.

In this specification, the term porous property may mean a case where porosity is at least <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, or <NUM>% or more. The upper limit of the porosity is not particularly limited, and may be, for example, less than about <NUM>%, about <NUM>% or less, or about <NUM>% or less or so. The porosity can be calculated in a known manner by calculating the density of the metal foam or the like.

The composite material has high thermal conductivity, and accordingly, it can be used as a material for controlling heat, such as a heat-dissipating material.

For example, the composite has a thermal conductivity of <NUM> W/mK or more, <NUM> W/mK or more, <NUM> W/mK or more, <NUM> W/mK or more, <NUM> W/mK or more, <NUM> W/mK or more, <NUM> W/mK or more. The higher the thermal conductivity of the composite material, the composite material may have more excellent thermal control functions, which is not particularly limited, and in one example, it may be about <NUM> W/mk or less, <NUM> W/mK or less, <NUM> W/mK or less, <NUM> W/mK or less, <NUM> W/mK or less, <NUM> W/mK or less, <NUM> W/mK or less, <NUM> W/mK or less, <NUM> W/mK or less, or <NUM> W/mk or less. The method of measuring the thermal conductivity is not particularly limited, which can be measured by, for example, the method described in the following examples.

The thermal conductivity of the composite material is measured by the method described in Examples to be described below.

Among physical properties mentioned in this specification, when the measured temperature affects relevant physical properties, the physical properties are physical properties measured at room temperature, unless otherwise specified. The term room temperature is a natural temperature without being heated or cooled, which may be, for example, any temperature in a range of <NUM> to <NUM>, or a temperature of about <NUM> or about <NUM> or so.

While the composite material of the present application has excellent heat conduction properties as above, other properties such as processability and impact resistance can be stably secured, and such effects can be achieved by the contents described in this specification.

The shape of the metal foam is a film. In the composite material of the present application, a polymer component existing on the surface or in the interior of the metal foam in the film form is added.

Such a polymer component may form a surface layer on at least one surface of the metal foam, or may be filled and present in the voids inside the metal foam, and in some cases, it may also be filled into the metal foam while forming the surface layer. In the case of forming a surface layer, the polymer component may form the surface layer on at least one surface, some surfaces, or all surfaces among surfaces of the metal foam. In one example, the polymer component may form the surface layer on at least the upper and/or lower surfaces, which are the main surfaces of the metal foam. The surface layer may be formed to cover the entire surface of the metal foam, or may also be formed to cover only a part of the surface.

The metal foam in the composite material may have porosity in a range of about <NUM>% to <NUM>%. The metal foam having this porosity has a porous metal framework forming a suitable heat transfer network, and thus it can ensure excellent thermal conductivity even if a small amount of the relevant metal foam is applied. In another example, the porosity may be <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, or <NUM>% or more, or may be <NUM>% or less.

As described above, the metal foam is in the form of a film. In this case, the thickness of the film can be adjusted in consideration of the desired thermal conductivity or thickness ratio, and the like, in manufacturing a composite material according to a method to be described below. In order to ensure the target thermal conductivity, the thickness of the film is about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, or about <NUM> or more. The upper limit of the thickness of the film is controlled according to the purpose, which is not particularly limited, and is about <NUM> or less, about <NUM> or less, about <NUM> or less, about <NUM> or less, or about <NUM> or less or so.

In this specification, when the thickness of the relevant target is not constant, the thickness may be a minimum thickness, a maximum thickness or an average thickness of the target.

The metal foam may be a material having high thermal conductivity. In one example, the metal foam may comprise or consist of a metal or a metal alloy having thermal conductivity of about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, about <NUM> W/mK or more, or about <NUM> W/mK or more. The thermal conductivity is not particularly limited, which may be, for example, about <NUM>,<NUM> W/mk or less or so, because the higher the numerical value, the desired thermal control characteristics can be ensured while applying a small amount of the metal foam.

The skeleton of the metal foam may be composed of various kinds of metals or metal alloys, where a material capable of exhibiting thermal conductivity in the above-mentioned range may be selected from these metals or metal alloys. Such a material can be exemplified by any metal selected from the group consisting of copper, gold, silver, aluminum, nickel, iron, cobalt, magnesium, molybdenum, tungsten and zinc, or an alloy of two or more thereof, and the like, but is not limited thereto.

Such metal foams are variously known, and also various methods for preparing metal foams are variously known. In the present application, such known metal foams or metal foams prepared by the known methods can be applied.

As a method for preparing a metal foam, a method of sintering a pore-forming agent such as a salt and a composite material of a metal, a method of coating a metal on a support such as a polymer foam and sintering it in this state or a slurry method, and the like is known. Furthermore, the metal foam can also be prepared by a method disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT>, and the like, which is a prior application of the present applicant.

The metal foam may also be prepared by the induction heating method from the methods described in the prior applications, where the metal foam may comprise at least a conductive magnetic metal. In this case, the metal foam may comprise <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, or <NUM> weight% or more of the conductive magnetic metal on the basis of weight. In another example, the ratio of the conductive magnetic metal in the metal foam may be about <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, <NUM> weight% or more, or <NUM> weight% or more. The upper limit of the ratio of the conductive magnetic metal is not particularly limited, and may be, for example, less than about <NUM> weight% or <NUM> weight% or less.

In the present application, the term conductive magnetic metal is a metal having predetermined relative magnetic permeability and conductivity, which may mean a metal capable of generating heat to such an extent that the metal can be sintered by the induction heating method.

In one example, as the conductive metal, a metal having relative magnetic permeability of <NUM> or more may be used. The relative magnetic permeability (µr) is a ratio (µ/µ<NUM>) of the magnetic permeability (µ) of the relevant material to the magnetic permeability (µ<NUM>) in the vacuum. In another example, the relative magnetic permeability may be <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, or <NUM> or more. The higher the relative magnetic permeability is, the higher the heat is generated at the time of application of the electromagnetic field for induction heating which is described below, whereby the upper limit is not particularly limited. In one example, the upper limit of the relative magnetic permeability may be, for example, about <NUM>,<NUM> or less.

The conductive magnetic metal may have conductivity at <NUM> of about <NUM>/m or more, <NUM>/m or more, <NUM>/m or more, <NUM>/m or more, <NUM>/m or more, <NUM>/m or more, or <NUM>/m or more. The upper limit of the conductivity is not particularly limited, and for example, the conductivity may be about <NUM>/m or less, <NUM>/m or less, or <NUM>/m or less.

A specific example of such a conductive magnetic metal includes nickel, iron or cobalt, and the like, but is not limited thereto.

The composite material further comprises a polymer component present on the surface of the metal foam or in the interior of the metal foam, as described above, wherein the ratio (T/MT) of the total thickness (T) of such a composite material to the thickness (MT) of the metal foam is <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, or <NUM> or less. The lower limit of the thickness ratio is not particularly limited, but in one example, it may be about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, or about <NUM> or more. Under such a thickness ratio, it is possible to provide a composite material having excellent processability or impact resistance, and the like, while ensuring the desired thermal conductivity.

The kind of the polymer component included in the composite material of the present application is not particularly limited, which may be selected in consideration of, for example, processability, impact resistance, insulation properties or the like of the composite material. An example of the polymer component applicable in the present application may include one or more selected from the group consisting of known acrylic resins, silicone resins, epoxy resins, urethane resins, amino resins, and phenol resins, but is not limited thereto.

In the case of the composite material, it is possible to secure excellent thermal conductivity while minimizing the ratio of components securing the thermal conductivity mainly through the application of the above-described metal foam, thereby securing the desired physical properties without damaging processability or impact resistance, and the like.

In one example, the ratio (MV/PV) of the volume (PV) of the polymer component and the volume (MV) of the metal foam contained in the composite material may be <NUM> or less. In another example, the ratio (MV/PV) may be <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, or <NUM> or less or so. The lower limit of the volume ratio is not particularly limited, which may be, for example, about <NUM> or so. The volume ratio can be calculated through the weight of the polymer component and the metal foam, included in the composite material, and the density of the relevant components.

The present application also relates to a method for preparing a composite material in the form as above. The method comprises a step of curing a curable polymer composition in a state where the polymer composition is present on the surface of or inside the metal foam, for example, the metal foam comprising a metal or a metal alloy having thermal conductivity of <NUM> W/mk or more and being in the form of a film.

The details of the metal foam applied in the method are as described above, and specific matters of the composite material to be prepared may also follow the contents as described above.

On the other hand, the polymer composition applied in the above is not particularly limited as long as it can form the above-mentioned polymer component through curing or the like, and such polymer components are variously known in the art.

That is, for example, the composite material can be prepared by performing the curing through a known method using a material having appropriate viscosity among known components.

The present application can provide a composite material which comprises a metal foam and a polymer component and has other excellent physical properties such as impact resistance, processability and insulation properties while having excellent thermal conductivity.

<FIG> are photographs of the composite materials produced in Examples, respectively.

Hereinafter, the present application will be described in detail by way of examples and comparative examples, but the scope of the present application is not limited to the following examples.

The metal foam was a copper metal foam, where the copper foam in a film shape with a thickness of about <NUM> or so and porosity of about <NUM>% was used. The copper metal foam was impregnated with a thermosetting epoxy resin composition comprising a thermosetting epoxy compound (Kukdo Chemical Co. , YD128) and a curing agent (Kukdo Chemical Co. , G640), and an excess of composition was removed using an applicator so that the thickness of the final composite material was about <NUM> or so. Subsequently, the material was maintained in an oven at about <NUM> for about <NUM> hour or so and cured to prepare a composite material. As a result of being calculated based on the density and the applied weight of each of the applied polymer component (epoxy resin) and metal foam (copper metal foam), the ratio (MV/PV) of the volume (PV) of the polymer component and the volume (MV) of the metal foam was about <NUM> or so. <FIG> is a photograph of the prepared composite material, and the thermal conductivity of this composite material was about <NUM> W/mK.

The thermal conductivity was determined by obtaining the thermal diffusivity (A), specific heat (B) and density (C) of the composite material and substituting them into an equation of thermal conductivity=ABC, where the thermal diffusivity was measured with a laser flash method (LFA equipment, model name: LFA467), the specific heat was measured by way of DSC (differential scanning calorimeter) equipment and the density was measured with Archimedes method. Also, the thermal conductivity is a value with respect to the thickness direction (Z axis) of the composite material.

A composite material was prepared in the same manner as in Example <NUM>, except that a thermosetting silicone composition (PDMS, Sylgard <NUM> kit) was used as the polymer composition, and the curing process was performed in an oven at <NUM> for about <NUM> minutes (final composite thickness: about <NUM> or so). As a result of being calculated based on the density and the applied weight of each of the applied polymer component (silicone resin) and metal foam (copper metal foam), the ratio (MV/PV) of the volume (PV) of the polymer component and the volume (MV) of the metal foam was about <NUM> or so. <FIG> is a photograph of the prepared composite material, and as a result of measuring the thermal conductivity of this composite material in the above-mentioned manner, it was about <NUM> W/mK.

A composite material was prepared in the same manner as in Example <NUM>, except that the thickness of the final composite material was about <NUM> and the curing process was performed at about <NUM> for about <NUM> minutes. As a result of being calculated based on the density and the applied weight of each of the applied polymer component (silicone resin) and metal foam (copper metal foam), the ratio (MV/PV) of the volume (PV) of the polymer component and the volume (MV) of the metal foam was about <NUM> or so. As a result of measuring the thermal conductivity of this composite material in the above-mentioned manner, it was about <NUM> W/mK.

A composite material was prepared in the same manner as in Example <NUM>, except that the polymer composition was changed to a thermosetting silicone composition (PDMS, Sylgard <NUM> kit) and the curing process was performed at about <NUM> for about <NUM> minutes. As a result of being calculated based on the density and the applied weight of each of the applied polymer component (silicone resin) and metal foam (copper metal foam), the ratio (MV/PV) of the volume (PV) of the polymer component and the volume (MV) of the metal foam was about <NUM> or so. As a result of measuring the thermal conductivity of this composite material in the above-mentioned manner, it was about <NUM> W/mK.

A composite material was prepared in the same manner as in Example <NUM>, except that the thickness of the final composite material was about <NUM> or so. As a result of being calculated based on the density and the applied weight of each of the applied polymer component (silicone resin) and metal foam (copper metal foam), the ratio (MV/PV) of the volume (PV) of the polymer component and the volume (MV) of the metal foam was about <NUM> or so. As a result of measuring the thermal conductivity of this composite material in the above-mentioned manner, it was about <NUM> W/mK.

The polymer composition applied in Example <NUM> was cured alone to form a film having a thickness of about <NUM> or so. The thermal conductivity of the formed film was about <NUM> W/mK.

Claim 1:
A composite material, comprising:
a metal foam and
a polymer component,
wherein the metal foam is in the form of a film and has a thickness of <NUM> or more and <NUM> or less,
wherein the polymer component is present on the surface of the metal foam or in the interior of the metal foam,
wherein the polymer component forms a surface layer on the surface of the metal foam,
wherein the ratio (T/MT) of the total thickness(T) to the thickness (MT) of the metal foam is <NUM> or less, and
wherein the thermal conductivity with respect to the thickness direction of the composite material according to the below Equation <NUM> is <NUM> W/mk or more: <MAT>
A is the thermal diffusivity of the composite material, B is specific heat of the composite material and C is a density of the composite material, wherein the thermal diffusivity is measured by laser flash method, specific heat is measured by differential scanning calorimeter DSC, and density is measured by Archimedes method.