KR101954650B1

KR101954650B1 - Composite sheet for absorbing impact

Info

Publication number: KR101954650B1
Application number: KR1020170010121A
Authority: KR
Inventors: 박종현; 류종호; 이재규; 정성헌
Original assignee: 일진머티리얼즈 주식회사
Priority date: 2017-01-23
Filing date: 2017-01-23
Publication date: 2019-03-06
Also published as: WO2018135916A1; KR20180086559A

Abstract

The present invention relates to a graphite layer; An adhesive layer provided on the graphite layer; A thermally conductive layer provided on the adhesive layer; And a shock absorbing layer directly provided on the thermally conductive layer, wherein the impact absorbing layer comprises a polymer foam. According to the present invention, by providing the impact absorbing layer directly on the heat conduction layer, it is possible to provide a shock absorbing composite sheet improved in heat radiation performance.

Description

Composite sheet for absorbing impact [0002]

More particularly, the present invention relates to a shock absorbing composite sheet, which can omit an interlaminar adhesive in a composite sheet to provide a thin shape, improve heat dissipation and impact absorption performance, apply graphite to a composite sheet, And more particularly to an improved composite sheet for shock absorption.

Electronic devices such as cell phones, hard disk drives (HDD), televisions and liquid crystal displays are made up of precision mechanical parts and electronic devices. In addition, recently, electronic devices and electronic parts tend to be thinned and simplified.

According to recent trends such as this, thinned and simplified electronic apparatuses are likely to be broken or damaged if a physical impact is applied from the outside, and space for mounting the electronic elements is narrow and electronic elements are integrated, The heat quantity was greatly increased. In addition, contaminants such as dust introduced from the outside interfere with the air flow in the electronic device, causing overheating of the electronic device, thereby shortening the lifetime of the electronic device.

Conventionally, when a shock absorber and a heat-radiating material are provided on a metal sheet, products formed by laminating an impact absorber and a metal sheet using an adhesive or the like have been used. In the case of products manufactured by such a method, in order to satisfy the impact absorbing performance and the heat radiation performance due to the use of the adhesive, the impact absorption performance or the heat radiation performance is decreased by the thickness of the adhesive provided on the metal sheet. There is a problem that the structure of the parts must be redesigned so that the absorption function or the heat radiation performance can be improved.

An object of the present invention is to provide a composite sheet excellent in heat radiation performance by further including graphite on one surface of a heat conduction layer.

Another object of the present invention is to provide a shock absorbing composite sheet improved in heat radiation performance by directly providing an impact absorbing layer on a heat conduction layer.

Another object of the present invention is to provide a shock absorbing composite sheet with improved process efficiency and reduced production cost by providing an impact absorbing layer directly on the heat conductive layer without using an interlayer adhesive in the composite sheet.

According to an aspect of the invention, an embodiment of the present invention provides a graphite layer; An adhesive layer provided on the graphite layer; A thermally conductive layer provided on the adhesive layer; And a shock absorbing layer directly provided on the thermally conductive layer, wherein the shock absorbing layer comprises a composite sheet for absorbing shock comprising a polymer foam.

The adhesive layer may be provided on one side of the graphite layer, and the insulator layer may be further formed on the other side of the graphite layer.

The cross-sectional area of the adhesive layer corresponds to the cross-sectional area of the insulator layer, and the graphite layer provided between the adhesive layer and the insulator layer may have a cross-sectional area smaller than that of the adhesive layer or the insulator layer.

The rim of the adhesive layer and the rim of the insulator layer may contact each other with the graphite layer therebetween to seal the graphite layer.

An impact absorbing layer may further be interposed between the adhesive layer and the heat conduction layer.

The graphite used for the graphite layer may be natural graphite or artificial graphite.

The thickness of the graphite layer may be in the range of 10 탆 to 100 탆.

The thickness of the graphite layer may be in the range of 15 탆 to 40 탆.

The polymeric foams may be selected from the group consisting of acrylic foams, polyurethane foams, polyethylene foams, polyolefin foams, polyvinyl chloride foams, polycarbonate foams, polyimide foams, polyetherimide foams, polyamide foams, polyester foams, polyvinylidene chloride foams, poly Methyl methacrylate foam, and polyisocyanate foam.

The density of the polymer foam may have a graphite of 0.2 g / cm ³ to 0.8 g / cm ^3.

The tensile strength of the polymer foam may be from 1 kgf / cm ² to 15 kgf / cm ² .

The tensile strength of the polymer foam was 2.5 kgf / cm < ² > To 12.5 kgf / cm < ² >.

The thickness of the polymer foam may be from 50 [mu] m to 250 [mu] m.

The thickness of the polymer foam may be 80 [mu] m to 150 [mu] m.

The thermally conductive layer may be at least one selected from the group consisting of copper, aluminum, plated copper, a mixture of copper and polymer, and plated aluminum.

The plating treatment may be performed using at least one of nickel, tin, cobalt, chromium, gold, and silver.

The thickness of the thermally conductive layer may be 8 [mu] m to 150 [mu] m.

The impact absorption layer may have an impact absorption rate of 5% to 50% and a recovery ratio of 50% to 100%.

The composite sheet may have an impact absorption rate of 1% to 30% and a recovery ratio of 50% to 100%.

The total thickness of the composite sheet for impact absorption may be 80 μm to 300 μm, and the impact absorbing layer may be 50 μm to 250 μm.

The composite sheet for impact absorption may further comprise an acrylic adhesive layer and a film layer on at least one of the outermost surfaces.

According to the present invention as described above, the composite sheet having excellent heat radiation performance can be provided by further including graphite on one surface of the heat conduction layer.

According to the present invention, a shock absorbing composite sheet having improved heat radiation performance can be provided by directly providing the impact absorbing layer to the heat conduction layer.

According to the present invention, it is possible to provide a shock absorbing composite sheet in which the process efficiency is improved and the production cost is reduced by directly providing the impact absorbing layer to the heat conduction layer without using the interlayer adhesive in the composite sheet.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view schematically showing the overall configuration of a shock absorbing composite sheet provided with graphite according to an embodiment of the present invention. Fig.
2 is a sectional view of a shock absorbing composite sheet having graphite according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view schematically illustrating a state in which an impact absorbing layer is directly provided on both sides of a heat conduction layer according to an embodiment of the present invention.

The details of other embodiments are included in the detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various forms. In the following description, it is assumed that a part is connected to another part, But also includes a case in which other media are connected to each other in the middle. In the drawings, parts not relating to the present invention are omitted for clarity of description, and like parts are denoted by the same reference numerals throughout the specification.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

Fig. 1 is a perspective view schematically showing the overall configuration of a shock absorbing composite sheet having graphite according to an embodiment of the present invention. Fig. 2 is a perspective view schematically showing a composite shock absorbing sheet having graphite according to an embodiment of the present invention. Fig.

1 and 2, the composite sheet for impact absorption according to an embodiment of the present invention includes a graphite layer 120; A thermally conductive layer 140 provided on one side of the graphite layer 120; And an impact absorbing layer 150 directly disposed on one or both surfaces of the thermally conductive layer 140. The insulator layer 110 and the adhesive layer 130 are provided on both surfaces of the graphite layer 120, The impact absorbing layer 150 may include a polymer foam.

The graphite used for the graphite layer 120 may be natural graphite or artificial graphite, and artificial graphite may be preferably used.

The thickness of the graphite layer may be 10 [mu] m to 100 [mu] m. If the thickness of the graphite layer is less than 10 탆, the workability may be deteriorated. If the thickness of the graphite layer is more than 100 탆, the heat dissipation performance may be decreased due to a decrease in density of the graphite sheet. More preferably, the thickness of the graphite layer may be between 15 탆 and 40 탆.

The heat conduction layer 140 may be at least one selected from among copper, aluminum, plated copper, and plated aluminum, preferably copper or copper foil. The plating treatment may be performed using at least one of nickel, tin, cobalt, chromium, gold, and silver. The copper foil may be any conventional copper foil known in the art without limitation, including all copper foils manufactured by rolling and electrolytic methods. More preferably, the electrolytic copper foil is not limited to the examples.

The thickness of the thermally conductive layer 140 may be 8 [mu] m to 150 [mu] m. If the thickness of the thermally conductive layer 140 is less than 8 占 퐉, the thermally conductive layer 140 may suffer from wrinkles or the like during the roll-to-roll operation, It can be a problem. If the thickness of the thermally conductive layer 140 is more than 150 占 퐉, curl may occur during the roll-to-roll operation, and the yield of the composite sheet may be decreased due to mass production, There is a problem because the sex is not good. Further, since the thickness of the heat conduction layer 140 is too thick, the application of the applicable composite sheet may be limited.

The impact absorbing layer 150 includes a polymer foam, and the polymer foam may be an acrylic foam, a polyurethane foam, a polyethylene foam, a polyolefin foam, a polyvinyl chloride foam, a polycarbonate foam, a polyimide foam, a polyetherimide foam, Amide foams, polyester foams, polyvinylidene chloride foams, polymethyl methacrylate foams, and polyisocyanate foams. Preferably, it may be a polyurethane foam or an acrylic foam.

The density of the polymer foam may be from 0.2 g / cm < ³ > to 0.8 g / cm < ³ >. If the density of the polymer foam is less than 0.2 g / cm ³ , the strength of the impact absorbing layer may be reduced and tear easily, the reworkability after adhesion may not be good, and the shock absorbing rate may be lowered, making it difficult to protect the substrate. When the density of the polymer foam is more than 0.8 g / cm ³ , the impact absorbing layer becomes solidified and the function of the foam is lost, so that the substrate can not be protected.

The tensile strength of the polymer foam may be from 1 kgf / cm ² to 15 kgf / cm ² . When the tensile strength of the polymer foam is 1 kgf / cm ² , The strength of the impact absorbing layer may be lowered, which may be easily broken or torn by an external force, and re-workability is not good even after attaching. In addition, the tensile strength of the polymer foam is too low, so that the shock absorption rate may be lowered, and it is difficult to protect the base material. When the tensile strength of the polymer foam exceeds 15 kgf / cm ² , the impact absorbing layer becomes hard and the substrate can not be protected. More preferably, the tensile strength of the polymer foam may be 2.5 kgf / cm ² to 12.5 kgf / cm ² .

The thickness of the polymer foam may be from 50 [mu] m to 250 [mu] m. If the thickness of the polymer foam is less than 50 탆, the shock absorption rate of the polymer foam may be lowered so that the substrate can not be protected. When the thickness of the polymer foam exceeds 250 탆, the heat radiation performance is decreased. The thickness of the composite sheet to which the foam is applied becomes too thick, which is problematic.

The polymer foam is formed by forming a large number of small bubbles inside a polymer material, and is relatively lightweight compared to a polymer material, and has flexibility and impact resistance. Therefore, the polymer foam can be widely applied as a packaging material, a buffer material, and a lightweight structural material. The method of producing the polymer foam may be a chemical method or a physical method. The chemical method is a method of producing a foam by generating a gas by decomposing the foaming agent after appropriately mixing the polymer resin and the foaming agent, The method is a method in which a foaming agent is infiltrated into a resin and then expanded under reduced pressure to produce a foam. Chemical methods can be applied mainly to the production of polyurethane foams and polyolefin foams, and physical methods can be applied mainly to prepare polystyrene foams and polyolefin foams.

In the production of polymer foams, a problem of environmental pollution has arisen, and a method of manufacturing synthetic resin foamed particles using physical methods rather than chemical methods has been widely adopted. Organic foaming agents such as CFC, propane, and butane and inorganic foaming agents such as carbon dioxide and nitrogen may be used as physical foaming agents, but the use of inorganic foaming agents such as carbon dioxide is increasing in consideration of air pollution.

FIG. 3 is a cross-sectional view schematically illustrating a state in which an impact absorbing layer is directly provided on both sides of a heat conduction layer according to an embodiment of the present invention.

2 and 3, the shock absorbing layer 150 may be directly provided on the heat conduction layer 140 without a connecting member such as an adhesive, a pressure sensitive adhesive, or the like, (140), or may be provided on both sides.

In the conventional case, the impact absorbing layer and the heat conduction layer are made of materials of different materials, and the surfaces between the shock absorbing layer and the heat conduction layer are not easily joined to each other. Is generally used. The composite sheet comprising the impact absorbing layer and the heat conductive layer and the adhesive interposed therebetween lowers the impact absorbing and heat radiation performance of the composite sheet by the thickness of the adhesive and unnecessarily increases the thickness of the composite sheet. Therefore, when the composite sheet is applied to an electric or electronic device having a limited thickness, there is a problem that the structure of the component must be additionally designed to compensate for the shock absorbing property and the heat dissipating property which are reduced by the thickness of the adhesive.

The shock absorbing composite sheet according to the present invention can firmly attach the impact absorbing layer 150 and the heat conduction layer 140 even though the adhesive is omitted between the impact absorbing layer 150 and the heat conduction layer 140. Therefore, it is possible to prevent the shock absorbing property and the heat radiation performance, which are conventionally caused by the use of the adhesive, from deteriorating. In addition, since the impact absorbing layer 150 is provided directly on the heat conduction layer 140, no adhesive is present between the impact absorbing layer 150 and the heat conduction layer 140, thereby reducing the thickness of the composite sheet. Further, the composite sheet for shock absorption according to the present invention may further comprise graphite, and the heat dissipation performance can be further improved by the graphite.

The impact absorption layer 150 may have an impact absorption rate of 5% to 50% and a recovery ratio of 50% to 100%. If the impact absorption rate of the impact absorbing layer 150 is less than 5% or less than 50%, the base material may not be protected and may be broken.

The composite sheet may have an impact absorption rate of 1% to 30% and a recovery ratio of 50% to 100%. If the shock absorptance of the composite sheet is less than 1% or the recovery rate is less than 50%, the composite sheet may not be suitable for applications such as electronic equipment, and the material comprising the composite sheet may not be adequately protected, I do not.

The total thickness of the composite sheet for impact absorption may be 80 μm to 300 μm, and the impact absorbing layer may be 50 μm to 250 μm. If the total thickness of the shock absorbing composite sheet is less than 80 占 퐉 or the thickness of the impact absorbing layer is less than 50 占 퐉, the base material may not be protected and may be broken.

The composite sheet for impact absorption according to the present invention may further include an acrylic adhesive layer 160 and a film layer 170 sequentially on one or both sides. The film layer 170 may be formed of a cellulose film such as a TAC (triacetyl cellulose) film or the like, a polyester film such as a polyethylene terephthalate (PET) film, a polycarbonate film, a polyethersulfone film, an acrylic film, A propylene film, a polyolefin film such as a cycloolefin or norbornene structure-containing polyolefin film, or an ethylene-propylene copolymer film, but the present invention is not limited thereto. More preferably, a releasable PET film having a releasing force of about 10 gf / in can be used to facilitate releasing.

The composite sheet for shock absorption with graphite according to the present invention is characterized in that the adhesive layer 130 is provided on one side of the graphite layer 120 and the insulator layer 110 is further provided on the other side of the graphite layer 120 . The graphite layer 120 interposed between the insulator layer 110 and the adhesive layer 130 is formed on the insulator layer 110 and the adhesive layer 130, The adhesive layer 130 may have a smaller cross-sectional area than the adhesive layer 130.

The insulator layer 110 and the adhesive layer 130 facing each other with the graphite layer 120 interposed therebetween are closely adhered to the graphite layer 120 to form the graphite layer 120, Can be sealed. Accordingly, the graphite layer 120 can be prevented from peeling off from the composite sheet.

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the scope of the present invention is not limited by the following examples.

Graphite Manufacture of composite sheet for impact absorption

[Example 1]

A copper foil having a thickness of 35 탆 and formed in a layer shape was prepared. The foaming agent was mixed with the polyurethane resin on the thus prepared copper foil, and the foaming agent was allowed to stand at a temperature of 200 占 폚 to form a polyurethane foam layer having a thickness of 105 占 퐉. Then, an acryl pressure-sensitive adhesive layer of 10 탆 was coated on the polyurethane foam layer and dried at 160 캜 for 3 minutes. The coating was carried out using a comma coater.

Thereafter, a copper foil and graphite were laminated using a 10 탆 adhesive layer and then sealed with a 10 탆 insulator layer on the graphite side to prepare a composite sheet having a total thickness of 190 탆.

Here, the acrylic adhesive layer may be provided as a kind of pressure-sensitive adhesive layer using acrylic, without bonding the foaming agent, and may be provided to bond neighboring materials, and means a material such as an acrylic foam having no air bubbles therein.

Example 1 was prepared so that a polyurethane foam was directly provided on a copper foil without using an adhesive or the like, and the values of the respective layers for Example 1 were as shown in Table 1.

[Example 2]

As shown in Table 1, a copper foil having a thickness of 40 占 퐉 was used, and a polyurethane foam layer was formed to have a thickness of 100 占 퐉.

[Example 3]

As shown in Table 1, a copper foil having a thickness of 45 탆 was used, and a polyurethane foam layer was formed to have a thickness of 95 탆.

[Example 4]

As shown in Table 4, a copper foil having a thickness of 35 탆 was used, and an acrylic foam layer was formed to have a thickness of 105 탆.

[Example 5]

As shown in Table 4, a copper foil having a thickness of 40 占 퐉 was used, and an acrylic foam layer was formed to have a thickness of 100 占 퐉.

[Example 6]

As shown in Table 4, a copper foil having a thickness of 45 탆 was used, and an acrylic foam layer was formed to have a thickness of 95 탆.

[Comparative Example 1]

As shown in Table 1, a copper foil having a thickness of 35 탆 was formed in the same manner as in Example 1, except that an acrylic adhesive layer having a thickness of 10 탆 was formed and a polyurethane foam layer was adhered.

[Comparative Example 2]

As shown in Table 1, a copper foil having a thickness of 70 탆 and a polyurethane foam layer were formed in the same manner as in Example 1, except that the foaming layer was formed in a thickness of 70 탆.

[Comparative Example 3]

As shown in Table 1, a composite sheet was prepared in the same manner as in Example 1, except that the adhesive layer was coated on the copper foil without polyurethane foaming and the graphite layering method described in Example 1 was used.

[Comparative Example 4]

As shown in Table 4, a copper foil having a thickness of 35 탆 was prepared in the same manner as in Example 4, except that the adhesive layer and the acrylic foam layer were omitted and the acrylic adhesive layer was directly bonded.

[Comparative Example 5]

As shown in Table 4, an adhesive layer was formed on a copper foil having a thickness of 35 占 퐉, and an acrylic foam layer having a thickness of 95 占 퐉 and an acrylic adhesive layer were bonded to each other.

[Comparative Example 6]

As shown in Table 4, a copper foil having a thickness of 70 占 퐉 was prepared in the same manner as in Example 4, except that an acrylic foam layer and an acrylic adhesive layer of 70 占 퐉 were adhered except for the adhesive layer.

The values for the copper foil layer, the adhesive layer (acrylic adhesive layer), the polyurethane foam layer / acrylic foam layer, the acrylic adhesive layer, the double-sided tape, the graphite and the total thickness of the composite sheets of Examples 1 to 6 and Comparative Examples 1 to 6 The results of evaluating the physical properties of the composite sheets of Examples 1 to 6 and Comparative Examples 1 to 6 are shown in Tables 2 and 3, Table 5 and Table 6 below The experimental method is as follows.

[Shock absorption rate measurement]

- Shock absorption rate measurement condition: 0.2 J (height: 45 cm, ball weight: 45 g free fall)

- Experimental method:

Place the prepared (PMMA + Acrylic) set on a shock absorber sensor.

Measure the impact absorption amount by dropping the ball in the state that the foam (Foam) is not inserted. Place the prepared (PMMA + Foam + Acrylic) set on the shock absorber sensor. With the foam inserted, measure the shock absorption by dropping the ball. The test is carried out 30 times per product, but the average value is calculated by the following formula 1, except for the Min / Max value where the impact value does not differ by more than 10%.

Equation 1:

[Compression set test method (ASTM D3574)]

The specimen is cut to a size of 50 mm x 50 mm and placed in a compression zig and compressed by 50% of the foam thickness using a flat gauge. Place in oven at 70 ℃ for 22 hours. Uncompress and verify unrecovered thickness. Tests are taken from the center in the width direction of each lot.

Calculations: C = [(t ₀ - t _i ) / (t ₀ - gauge thickness)] x 100

t ₀ initial thickness / t ₁ thickness after test

[Dupont impact]

The DuPont impact test was performed by evaluating the bond strength (cracking, peeling) by dropping the weights of a certain height and a constant load after the specimen was horizontally raised and the punch of radius was touched.

The shock absorbing layer Polyurethane A foam layer Occation

Copper foil layer
(탆) Adhesive layer
(탆) Polyurethane
Foam layer
(탆) acryl
Adhesive layer
(탆) Insulator layer
(탆) Adhesive layer
(탆) Graphite
(탆) Total thickness
(탆) Example 1 35 0 105 10 10 10 20 190 Example 2 40 0 100 10 10 10 20 190 Example 3 45 0 95 10 10 10 20 190 Comparative Example 1 35 10 95 10 10 10 20 190 Comparative Example 2 70 0 70 10 10 10 20 190 Comparative Example 3 35 - - 10 10 10 20 85

Compressive strength
(kg / cm ² ) Recovery rate
(%) Dupont
Impact
(mJ) Compression set
(%) Dimensional stability
(%) Thermal conductivity
(W / mK) Example 1 2.29 99.71 0.192 <3 <1 193 Example 2 2.21 99.29 0.179 <3 <1 203 Example 3 1.99 99.55 0.171 <3 <1 213 Comparative Example 1 2.15 99.10 0.160 <3 <1 192 Comparative Example 2 1.80 99.23 0.138 <3 <1 261 Comparative Example 3 Not measurable Not measurable 0.035 Not measurable <1 408

Tensile strength of the impact absorbing layer
(kgf / cm ² ) Compression se of shock absorbing layer
(%) t Of the shock absorbing layer
Shock absorption rate
(%) Composite sheet
Shock absorption rate
(%) Example 1 5.37 <3 16.72 16.90 Example 2 5.13 <3 15.03 15.50 Example 3 4.70 <3 14.17 14.25 Comparative Example 1 4.63 <3 14.10 14.22 Comparative Example 2 3.79 <3 8.37 8.64 Comparative Example 3 Not measurable Not measurable Not measurable 0.22

The shock absorbing layer acryl A foam layer Occation

Copper foil
(탆) Adhesive layer
(탆) acryl
Foam layer
(탆) acryl
Adhesive layer
(탆) Insulator layer
(탆) Adhesive layer
(탆) Graphite
(탆) Total thickness
(탆) Example 4 35 0 105 10 10 10 20 190 Example 5 40 0 100 10 10 10 20 190 Example 6 45 0 95 10 10 10 20 190 Comparative Example 4 35 0 0 10 10 10 20 85 Comparative Example 5 35 10 95 10 10 10 20 190 Comparative Example 6 70 0 70 10 10 10 20 190

Compressive strength
(kg / cm ² ) Recovery rate
(%) Dupont
Impact
(mJ) Compression set
(%) Dimensional stability
(%) Thermal conductivity
(W / mK) Example 4 3.31 99.34 0.241 <3 <1 194.1 Example 5 3.18 99.59 0.227 <3 <1 202.0 Example 6 3.04 99.15 0.216 <3 <1 213.6 Comparative Example 4 Not measurable Not measurable 0.035 Not measurable <1 408.9 Comparative Example 5 3.03 99.52 0.203 <3 <1 193.1 Comparative Example 6 2.37 99.31 0.191 <3 <1 260.9

Of the shock absorbing layer
The tensile strength
(kgf / cm ² ) Compression set of shock absorbing layer
(%) Of the shock absorbing layer
Shock absorption rate
(%) Composite sheet
Shock absorption rate
(%) Example 4 10.75 <3 19.39 19.50 Example 5 10.47 <3 18.42 18.70 Example 6 10.04 <3 17.30 17.95 Comparative Example 4 Not measurable Not measurable Not measurable 0.22 Comparative Example 5 10.04 <3 17.30 17.63 Comparative Example 6 8.89 <3 15.57 15.91

In Table 2 and Table 3, in the case of Comparative Example 1 which is a composite sheet including a bonding layer, the specific gravity of the adhesive layer in the composite sheet is not large at 10 占 퐉. However, And DuPont impact test results were lower than those of Example 1, and the adhesion strength was also not high.

In the case of Comparative Example 2, the copper foil had a thickness of 70 탆 and the thermal conductivity was relatively high. However, the impact absorption layer was thick at 70 탆, which was low in the restoration ratio, compressive strength, shock absorption rate test and DuPont impact test .

In Comparative Example 3, no impact absorbing layer was provided, and it was impossible to measure the compressive strength, the recovery ratio, the compression set, the tensile strength of the impact absorbing layer, the compression set of the impact absorbing layer, and the shock absorbing rate to the impact absorbing layer in Tables 2 and 3.

Compared to Comparative Example 3, in the case of Examples 1 to 3, the thermal conductivity was lower than that of the composite sheet produced using only the copper foil (Comparative Example 3) And shows good results in terms of compression strength and restoration ratio.

That is, in the case of Examples 1 to 3, the tensile strength of the impact absorbing layer, the impact absorbing rate to the impact absorbing layer, and the impact absorbing rate to the composite sheet are excellent in comparison with Comparative Examples 1 to 3 In the case of Comparative Example 2 and Comparative Example 3 in which the tensile strength of the impact absorbing layer is remarkably low, the impact absorbing rate for the impact absorbing layer and the shock absorbing rate for the composite sheet are significantly lower than those of Examples 1 to 3 .

In Examples 1 to 3, the tensile strength of the impact absorbing layer, the impact absorbing rate of the impact absorbing layer, and the impact absorbing rate of the composite sheet are excellent in comparison with Comparative Examples 1 to 3 In the case of Comparative Example 2 and Comparative Example 3 in which the tensile strength of the impact absorbing layer is remarkably low, the impact absorbing rate for the impact absorbing layer and the shock absorbing rate for the composite sheet are significantly lower than those of Examples 1 to 3 .

It was confirmed that Examples 1 to 3 had better results than Comparative Examples 1 and 2 in the case where both the adhesive layer and the impact absorbing layer were provided, even though there was no adhesive layer capable of having a buffer function against impacts and the like.

Table 3 shows that the impact absorption rate of the composite sheet is lower than that of the impact absorbing layer. This is because the composite sheet has a total impact absorption rate with the copper foil. Therefore, The result is that the shock absorption rate is further decreased by the copper foil. That is, as the thickness of the copper foil increases, the impact absorption rate of the entire composite sheet is relatively reduced.

Tables 4 to 6 show the results of confirming the polymer release layer as an impact absorbing layer using an acrylic foam layer. When the acrylic adhesive layer, the adhesive layer, and the acrylic foam layer were not present as in Comparative Example 4, the results on the impact absorbing layer (tensile strength, compression set, etc.) could not be confirmed.

It was confirmed that Examples 4 to 6 had better results than Comparative Examples 5 and 6 in which both the adhesive layer and the impact absorbing layer were provided, even though there was no adhesive layer capable of having a buffer function against impacts and the like.

In the case of Examples 4 to 6 according to the present example, it was confirmed that even though the adhesive layer is omitted in comparison with Comparative Example 4, the result is more excellent.

Referring to Table 6, it can be confirmed that the impact absorption rate of the composite sheet is higher than that of the impact absorption layer. Generally, the composite sheet contains a copper foil, so that the shock absorption rate tends to be lowered by the copper foil. On the other hand, the composite sheet according to the present embodiment further includes graphite, and further includes an adhesive layer for fixing the graphite in the composite sheet. The additional adhesive layer has a buffer function due to an external force in the composite sheet, whereby the shock absorption rate of the composite sheet is higher than that of the pressure-sensitive adhesive layer.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

100: composite sheet
110: insulator layer
120: graphite layer
130: adhesive layer
140: heat conduction layer
150: shock absorbing layer
160: acrylic adhesive layer
170: release film layer

Claims

Graphite layer;
An adhesive layer provided on one surface of the graphite layer;
A thermally conductive layer provided on the adhesive layer; And
And an impact absorbing layer directly disposed on the heat conduction layer,
Wherein the impact absorbing layer comprises a polymer foam,
Wherein the adhesive layer is provided on one side of the graphite layer and further includes an insulator layer on the other side of the graphite layer,
Wherein a cross-sectional area of the adhesive layer corresponds to a cross-sectional area of the insulator layer, and a graphite layer provided between the adhesive layer and the insulator layer is provided in a cross-sectional area smaller than that of the adhesive layer or the insulator layer,
Wherein the rim of the adhesive layer and the rim of the insulator layer contact each other with the graphite layer interposed therebetween to seal the graphite layer.

delete

The method according to claim 1,
And a shock absorbing layer between the adhesive layer and the heat conductive layer.

The method according to claim 1,
Wherein the graphite used for the graphite layer is natural graphite or artificial graphite.

The method according to claim 1,
Wherein the thickness of the graphite layer is 10 占 퐉 to 100 占 퐉.

8. The method of claim 7,
Wherein the thickness of the graphite layer is 15 占 퐉 to 40 占 퐉.

The method according to claim 1,
The polymeric foams may be selected from the group consisting of acrylic foams, polyurethane foams, polyethylene foams, polyolefin foams, polyvinyl chloride foams, polycarbonate foams, polyimide foams, polyetherimide foams, polyamide foams, polyester foams, polyvinylidene chloride foams, poly Methyl methacrylate foam, polyisocyanate foam, and the like.

10. The method of claim 9,
Wherein the polymer foam is a polyurethane foam or an acrylic foam.

The method according to claim 1,
The density of the polymer foam is 0.2 g / cm ³ to 0.8 g / cm ³ The impact-absorbing composite sheet.

The method according to claim 1,
Wherein the polymer foam has a tensile strength of 1 kgf / cm ² to 15 kgf / cm ² .

The method according to claim 1,
The tensile strength of the polymer foam was 2.5 kgf / cm < ² > To 12.5 kgf / cm < ² >.

The method according to claim 1,
Wherein the polymer foam has a thickness of 50 占 퐉 to 250 占 퐉.

15. The method of claim 14,
Wherein the polymer foam has a thickness of 80 mu m to 150 mu m.

The method according to claim 1,
Wherein the thermally conductive layer is at least one selected from the group consisting of copper, aluminum, plated copper, a mixture of copper and polymer, and plated aluminum.

17. The method of claim 16,
Wherein the plating treatment is a plating treatment using at least one of nickel, tin, cobalt, chromium, gold and silver.

The method according to claim 1,
Wherein the thermally conductive layer has a thickness of 8 mu m to 150 mu m.

19. The method according to any one of claims 1 to 18,
Wherein the impact absorbing layer has an impact absorption rate of 5% to 50% and a recovery ratio of 50% to 100%.

The method according to claim 1,
Wherein the shock absorbing composite sheet has an impact absorption rate of 1% to 30% and a recovery ratio of 50% to 100%.

The method according to claim 1,
Wherein the total thickness of the shock absorbing composite sheet is 80 占 퐉 to 300 占 퐉 and the impact absorbing layer is 50 占 퐉 to 250 占 퐉.

The method according to claim 1,
Wherein the impact absorbing composite sheet further comprises an acrylic adhesive layer on at least one of the outermost surfaces and a film layer provided on the acrylic adhesive layer.