KR20150062471A - Thermal conductive composition for dual bonding having improved adhesive property with substrate - Google Patents

Abstract

The present invention relates to a dual boding composition having improved thermal conductivity and adhesion with a resin. More specifically, a block tricopolymer of an aromatic vinyl compound and a conjugated diene-based compound and a thermally conductive filler are included, thereby ensuring excellent thermal conductivity and hardness and remarkably improving adhesion with a base material, because dual injection is possible.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermally conductive double bonding composition having improved bonding properties to a substrate. [0002]

The present invention relates to a thermally conductive double bonding composition having improved bonding properties to a base material, and more particularly, to a thermally conductive double bonding composition comprising an aromatic vinyl compound and a block terpolymer of a conjugated diene compound and a thermally conductive filler, And capable of double injection, whereby bonding properties to a substrate are remarkably improved.

 Electric and electronic devices with heat-generating components Metal has been the most widely used to date for most heat sinks, boards, housings, connectors, and other materials. Metals with high thermal conductivity can dissipate heat faster than other materials, protecting heat-sensitive electrical and electronic components from localized high-temperature heat. Further, the metal has high mechanical strength and is suitable for a heat dissipation material having a complicated shape due to easy processing of a sheet metal or a metal mold.

However, metal has a disadvantage that it is difficult to reduce weight because of its high density and high unit cost. In order to solve these drawbacks, the development of thermally conductive materials using polymer resins is continuing.

Recently, due to the high integration and high performance of electronic devices, more and more heat is being generated in the device, and as the devices become thinner and lighter, it becomes difficult to rapidly diffuse the generated heat to the surroundings.

As a result, the occurrence of localized high temperatures leads to malfunction and ignition of electronic devices. However, the low thermal conductivity of the thermally conductive resin developed so far has a limit to solve such a problem.

As the thermal conductivity of the thermally conductive resin is improved and the thermally conductive filler is filled in a larger amount, the viscosity of the thermally conductive resin increases, and the extrusion and injection moldability are significantly decreased, which makes it difficult to produce the product.

In addition, as a heat-dissipating material, a silicone pad type in which a thermally conductive filler is added to silicon as a thermosetting resin to form and cure the silicone pad is widely used. However, silicon rubber generates low molecular siloxane at a high temperature, which can lead to poor contact with an electric circuit, etc., and it is difficult to realize various shapes due to incapability of injection, a long production time, and a high unit cost.

Korean Patent Laid-Open Publication No. 2013-0057411 (Patent Document 1) discloses a thermally conductive elastomer composition in which a thermally conductive filler surface-treated to a thermoplastic elastomer composition is added to improve thermal conductivity. However, as the content of the thermally conductive filler increases, the molding workability such as extrusion and injection remarkably decreases, and the bonding property between the resins is poor, so that double injection is difficult.

Accordingly, there is still a demand for development of a flexible thermoplastic injection material which has excellent thermal conductivity as well as excellent injection-processability and excellent bonding property to a base material and which can be double-injected.

Korean Patent Publication No. 2013-0057411

In order to solve the above problems, it is an object of the present invention to provide a thermally conductive double bonding composition having a high heat dissipation property and improved bonding property to a substrate. More specifically, by adding a thermally conductive filler to a block terpolymer of an aromatic vinyl compound and a conjugated diene compound, the thermally conductive filler is excellent in thermal conductivity and excellent in bonding properties with various substrates such as polycarbonate and polyolefin, It is an object of the present invention to provide a composition for double bonding.

It is also an object of the present invention to provide a thermally conductive double bonding composition which is flexible, has a soft touch, and is excellent in surface hardness.

It is another object of the present invention to provide a molded article made of a thermally conductive double bonding composition.

The present invention provides a method for producing a block copolymer comprising (A) 100 parts by weight of a block terpolymer of an aromatic vinyl compound (Ar, Ar ') having an Ar-CD-Ar structure and a conjugated diene compound , And (B) 40 to 1500 parts by weight of a thermally conductive filler.

(A) may be a styrene-ethylene butadiene-styrene (SEBS) block copolymer, a styrene-ethylene propylene-styrene (SEPS) block copolymer, a styrene-isoprene-styrene (SIS) block copolymer, styrene-ethylene isoprene- SEIS) block copolymers and styrene-ethylene ethylene propylene-styrene (SEEPS) block copolymers.

The composition for double bonding may further comprise a softening agent (C) and an ethylene polymer (D).

The amount of the softener (C) is 10 to 200 parts by weight based on 100 parts by weight of the block terpolymer (A); And 10 to 150 parts by weight of the ethylene-based polymer (D).

The (D) softener may include paraffin oil having a kinetic viscosity of 95 to 215 cSt (@ 40 DEG C), and the ethylene polymer (D) may be an ethylene vinyl acetate copolymer (EVA), ethylene methyl acrylate (EEA) copolymer, an ethylene acrylic acid (EAA) copolymer, an ethylene butyl acrylate (EBA) copolymer and a low density polyethylene (LDPE) may be selected.

The thermally conductive filler (B) may be selected from at least one of magnesium oxide (MgO), alumina, aluminum nitride (AlN) and boron nitride (BN).

In order to achieve the above object, the present invention relates to a molded article formed from the above-described composition for double bonding.

The molded article may satisfy the following formulas (1) and (2).

2.0? Tc? 5.0 [Formula 1]

0.5? As? 3.0 [Formula 2]

(In the above Equation 1, Tc is the thermal conductivity (W / mK) measured in accordance with ASTM E1461 standard, and As is the bonding strength (N / m) with PC or PP specimen).

The composition for thermally conductive double bonding according to the present invention is excellent in dispersibility in a block terpolymer of an aromatic vinyl compound and a conjugated diene compound without a surface treatment of the thermally conductive filler to increase the content of the thermally conductive filler There is an advantage in that the processability such as extrusion or injection molding is excellent.

Further, by further including an ethylene polymer in the thermally conductive double-bonding composition of the present invention, bonding properties with various substrates such as a polyolefin-based resin and a polycarbonate-based resin are remarkably improved. Due to these characteristics, there is an advantage that double injection can be performed.

There is an advantage in that it is a high heat dissipation heat conductive material such as a housing of an electric and electronic material which is thin and has a high degree of integration because it maintains flexible and soft characteristics at the same time and is excellent in mechanical properties such as hardness.

One embodiment of the present invention relates to a thermally conductive double bonding composition having improved bonding properties to a substrate. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. It will be apparent to those skilled in the art that, unless otherwise defined, technical terms and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, And a description of the known function and configuration will be omitted.

The inventors of the present invention have studied to develop a composition for double bonding which is capable of double injection by adding a conductive filler to a thermoplastic elastomer and having excellent bonding property with a base material and mechanical properties. As a result, it has been found that a block copolymer of an aromatic vinyl compound and a conjugated diene compound It has been found that the addition of a thermally conductive filler to a copolymer improves the bonding property with various substrates such as polyolefin and polycarbonate systems, enables double injection, and exhibits a flexible and smooth surface, thereby completing the present invention.

In the present invention, the term " double junction "means a bonding between a heat dissipating material and a non-heat dissipating material, and the thermoconductive double bonding composition means a composition having double bonding characteristics suitable for double injection and having excellent thermal conductivity. Means co-extrusion without special additional processing, or bonding between materials by injection method.

Hereinafter, each component will be described in more detail.

(A) an aromatic vinyl compound and Conjugated diene series  Compound Block terpolymer

The block ternary copolymer of an aromatic vinyl compound and a conjugated diene compound according to an embodiment of the present invention can be used for the surface ductility characteristics of a thermally conductive double bonding composition.

In the block terpolymer, the aromatic vinyl compound (Ar, Ar ') and the conjugated diene compound (CD) may form an Ar-CD-Ar' structure. The Ar and Ar 'blocks are hard segments, and the CD blocks are soft segments. The hard segments are intended to prevent thermoplastic deformation, and the soft segments exhibit rubber properties. Various properties such as hardness, heat resistance, chemical resistance, and abrasion resistance can be implemented depending on the types of hard segment and soft segment, content, molecular weight and arrangement. In one example, the hard segment may be 20-35 wt% and the soft segment may be 65-80 wt%. More specifically, the hard segment may be 27 to 35 wt%, and the soft segment may be 65 to 73 wt%.

The aromatic vinyl compound (Ar, Ar ') is an aromatic vinyl-based polymer, and more specifically, it may be a styrene-based polymer. The conjugated diene compound (CD) is a conjugated diene polymer, and ethylene-butadiene, isoprene, ethylene-isoprene, and ethylene-propylene polymer can be selected. Preferably ethylene butadiene.

The block terpolymer (A) may be at least one selected from the group consisting of a styrene-ethylene butadiene-styrene (SEBS) block copolymer, a styrene-ethylene propylene-styrene (SEPS) block copolymer, a styrene-isoprene- Isoprene-styrene block copolymer (SEIS), styrene-ethylene ethylene propylene-styrene (SEEPS) block copolymer, and the like. These may be used alone or in combination of two or more.

Of these, styrene-ethylene butadiene-styrene (SEBS) block copolymers, styrene-ethylene propylene-styrene (SEPS) block copolymers, styrene-isoprene-styrene (SIS) block copolymers and styrene- ≪ / RTI > copolymers (SEIS).

The block terpolymer may have a weight average molecular weight of 140,000 to 180,000 g / mol. More specifically from 147,000 to 170,000 g / mol.

(B) Thermal conductivity filler

The thermally conductive filler according to one embodiment of the present invention is added to the block terpolymer of the aromatic vinyl compound and the conjugated diene compound to improve the thermal conductivity of the composition for double bonding.

Materials that can be used as thermally conductive fillers having high thermal conductivity include carbon-based fillers such as carbon fiber, carbon nanotube, carbon nano fiber, and graphite, and metals There is powder.

However, carbon-based fillers and metal powders have high thermal conductivity as well as high electrical conductivity. Thus, more preferably, any electrically insulating, thermally conductive filler known in the art as a thermally conductive filler in the present invention can be used without limitation. For example, one or more of magnesium oxide (MgO), alumina, aluminum nitride (AlN) and boron nitride (BN) may be selected.

The shape of the thermally conductive filler may be spherical or plate-like. And more preferably spherical for improving the thermal diffusivity and fluidity. The spherical thermally conductive filler is excellent not only in the horizontal direction but also in the vertical direction so that the thermal conductivity can be remarkably improved regardless of the directionality.

The average particle diameter of the thermally conductive filler may be 30 to 80 占 퐉. More preferably 40 to 60 占 퐉. If the average particle diameter is less than 30 탆, the fluidity may be deteriorated, and if it is more than 80 탆, the thermal conductivity may be deteriorated.

The thermally conductive filler according to one embodiment of the present invention may contain 40 to 1500 parts by weight based on 100 parts by weight of the block terpolymer of the aromatic vinyl compound and the conjugated diene compound. More preferably 200 to 1400 parts by weight.

When the content of the thermally conductive filler is less than 40 parts by weight, the thermal conductivity of the molded product may be insufficient. When the content of the thermally conductive filler is more than 1500 parts by weight, the fluidity may decrease and the moldability may remarkably decrease. In addition, the impact strength of the molded article can be reduced.

(C) Softener

The softening agent according to one embodiment of the present invention is added for the purpose of improving the elongation percentage. The softening agent is well known in the art and can be used without limitation as long as it is compatible with a block terpolymer (thermoplastic elastomer). As an example, paraffin oil or naphthenic oil may be used.

The weight average molecular weight of the softening agent may be 400 to 1,200 g / mol, and may be 600 to 900 g / mol. In addition, the softener may have a kinematic viscosity of 95 to 215 cSt at 40 DEG C, and may be 100 to 210.5 cSt.

When the paraffin oil is used in the above-mentioned range, it is advantageous in mixing during extrusion or injection molding. In addition, when the content is out of the above-mentioned range, gas may be generated at the time of molding or tacky when molded into a molded product, which may reduce the processability.

The softening agent according to an embodiment of the present invention may contain 10 to 200 parts by weight based on 100 parts by weight of the block terpolymer of the aromatic vinyl compound and the conjugated diene compound.

If the content of the softening agent is less than 10 parts by weight, there may be a problem that the workability during injection molding may be deteriorated. If the content is more than 200 parts by weight, sticking may occur due to bleeding phenomenon.

(D) Ethylene polymer

The ethylene polymer according to one embodiment of the present invention may be added to improve the bonding property to various substrates of the composition for thermally conductive double bonding.

The ethylene polymer may be selected from the group consisting of ethylene vinyl acetate copolymer (EVA), ethylene methyl acrylate (EMA) copolymer, ethylene ethyl acrylate (EEA) copolymer, ethylene acrylic acid (EAA) copolymer, ethylene butyl acrylate And a low density polyethylene (LDPE) may be selected, but not limited thereto. More preferably, it may be an ethylene methyl acrylate (EMA) copolymer.

The ethylene polymer according to an embodiment of the present invention may contain 10 to 150 parts by weight based on 100 parts by weight of the block terpolymer of the aromatic vinyl compound and the conjugated diene compound. Preferably 30 to 100 parts by weight.

When the content of the ethylene polymer is less than 10 parts by weight, bonding property may occur. When the content of the ethylene polymer is more than 150 parts by weight, the HDT (heat distortion temperature) may be too low to cause problems.

The composition for thermally conductive double bonding according to the present invention may be selected from the group consisting of an antioxidant, a lubricant, a flame retardant, a heat stabilizer, an inorganic additive, a pigment, a dye and a mixture thereof to improve physical properties and processability without hindering thermal conductivity Based on the total weight of the composition.

Conventional additives may be used in an amount of 30% by weight or less based on 100% by weight of the thermally conductive double bonding composition of the present invention.

The composition for thermally conductive double bonding of the present invention can be prepared by a known method. For example, each component and additives are mixed with a Henschel mixer, a V blender, a tumbler blender, a ribbon blender, etc., and melt-extruded at a temperature of 150 to 300 ° C using a single screw extruder or a twin screw extruder to produce a pellet . More specifically, extrusion was carried out using a twin-screw extruder having L / D of 20 to 60, Φ = 32 mm and 70 mm under the conditions of a fixed temperature of 240 ° C., a screw rotating speed of 300 to 600 rpm and a self- Whereby a pellet phase can be produced.

According to another embodiment of the present invention, there is provided a molded article produced by molding the composition for thermally conductive double bonding described above. That is, the thermally conductive double bonding composition can be used to produce a molded article by various processes such as injection molding, double injection molding, blow molding, extrusion molding, and thermoforming.

The molded article of the present invention can satisfy the following formulas (1) and (2).

2.0? Tc? 5.0 [Formula 1]

0.5? As? 3.0 [Formula 2]

(In the above Equation 1, Tc is the thermal conductivity (W / mK) measured in accordance with ASTM E1461 standard, and As is the bonding strength (N / m) with PC or PP specimen).

In particular, it can be applied to a variety of applications such as housings, bodies, heat sinks, and LED heat sinks for electrical and electronic products such as TVs, computers, mobile phones, and office automation devices that require excellent thermal conductivity.

Hereinafter, preferred embodiments of the present invention and methods for measuring properties thereof will be described in detail. The present invention may be better understood by the following examples, which are for the purpose of illustrating the present invention and are not intended to limit the scope of protection defined by the appended claims.

How to measure property

(One) Surface hardness (shore A)

The surface hardness was measured with Shore A according to KS M 6518 standard.

(2) Thermal Conductivity Measurement

The thermal conductivity (W / mK) was measured according to the ASTM E 1530 standard.

(3) Bond strength measurement

In accordance with KS M 6518, a polycarbonate with a primary side of 5 cm x 20 cm was extruded into a 5 cm x 20 cm rectangular primary specimen, and then the secondary side of the elastomer part was bent 180 °. This part was joined using a UTM device (shimadzu) The load until removal was measured. The results were calculated by dividing by the length of the joint.

[Example 1]

As shown in Table 1 below, the block triple copolymer (SEBS, hard segment is styrene, content is 33 wt%, soft segment is ethylene butadiene, content is 67 wt%, total molecular weight is 150,000 g / 100 parts by weight of a thermally conductive filler (G1651, manufactured by Nippon Kayaku Co., Ltd.) and 235 parts by weight of a thermally conductive filler (MgO having an average particle diameter of 50 탆, UBE Company and RF-50) 45 mm diameter twin-screw extruder to prepare a resin composition in the form of a pellet. The pellets thus obtained were dried at 90 DEG C for 3 hours or more, and their physical properties were measured at an injection temperature of 300 DEG C in a 10 oz injection machine.

[Example 2-7]

As shown in the following Table 1, specimens were prepared in the same manner as in Example 1 except that the contents of the respective components were changed. The properties were measured and the results are shown in Table 2 below.

[Comparative Example 1-3]

As shown in the following Table 1, specimens were prepared in the same manner as in Example 1 except that the contents of the respective components were changed. The properties were measured and the results are shown in Table 2 below.

[Table 1]

 [Table 2]

As shown in Table 2, from Examples 1 to 7 of the present invention, by containing the block ternary copolymer, the softening agent, the ethylene polymer and the thermally conductive filler in an optimum amount, it is possible to obtain a polyolefin- And the surface hardness and the thermal conductivity are remarkably improved.

On the other hand, referring to Comparative Example 1, which does not include a thermally conductive filler, softening agent and ethylene polymer, and Comparative Example 2, which does not include an ethylene polymer, mechanical properties and thermal conductivity are remarkably reduced and bonding with polycarbonate is deteriorated .

In Comparative Example 3, although the surface hardness and the thermal conductivity were good, the bonding property with the polycarbonate was poor, and the balance of the physical properties was deteriorated.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is clear that the present invention can be suitably modified and applied in the same manner. Therefore, the above description does not limit the scope of the present invention, which is defined by the limitations of the following claims.

Claims (9)

(A) 100 parts by weight of a block terpolymer of an aromatic vinyl compound (Ar, Ar ') having an Ar-CD-Ar' structure and a conjugated diene compound (CD)
(B) 40 to 1500 parts by weight of a thermally conductive filler.
The method according to claim 1,
(A) may be a styrene-ethylene butadiene-styrene (SEBS) block copolymer, a styrene-ethylene propylene-styrene (SEPS) block copolymer, a styrene-isoprene-styrene (SIS) block copolymer, styrene-ethylene isoprene- SEIS) block copolymers and styrene-ethylene ethylene propylene-styrene (SEEPS) block copolymers.
The method according to claim 1,
Wherein the composition for double bonding further comprises a softening agent (C) and an ethylene polymer (D).
The method of claim 3,
With respect to 100 parts by weight of the block (A) terpolymer,
(C) 10 to 200 parts by weight of a softening agent; And
Wherein the ethylene polymer (D) comprises 10 to 150 parts by weight of the ethylene polymer.
The method of claim 3,
Wherein the softener (D) comprises a paraffin oil having a kinetic viscosity of 95 to 215 cSt (@ 40 DEG C).
The method of claim 3,
The ethylene polymer (D) is at least one selected from the group consisting of ethylene vinyl acetate copolymer (EVA), ethylene methyl acrylate (EMA) copolymer, ethylene ethyl acrylate (EEA) copolymer, ethylene acrylic acid (EAA) copolymer, ethylene butyl acrylate EBA) copolymer and low density polyethylene (LDPE).
The method according to claim 1,
Wherein the thermally conductive filler (B) is at least one selected from the group consisting of magnesium oxide (MgO), alumina, aluminum nitride (AlN) and boron nitride (BN).
A molded article formed from the composition for double bonding according to any one of claims 1 to 7.
9. The method of claim 8,
Wherein the molded article satisfies the following formulas (1) and (2).
2.0? Tc? 5.0 [Formula 1]
0.5? As? 3.0 [Formula 2]
(In the above Equation 1, Tc is the thermal conductivity (W / mK) measured in accordance with ASTM E1461 standard, and As is the bonding strength (N / m) with PC or PP specimen).