KR20220069255A - Thermally conductive plastic - Google Patents

Abstract

A thermally conductive plastic according to the present invention comprises: a thermally conductive bead including a first thermally conductive filler having an aspect ratio of 30 or more on a surface; a second thermally conductive filler having an aspect ratio of 3 to 20; a poly(acrylonitrile-butadiene-styrene) copolymer; and a polyolefin.

Description

Thermally conductive plastic

The present invention relates to a thermally conductive plastic having excellent mechanical strength as well as thermal conductivity.

Polymers are easy to mold and inexpensive, so they are used in various fields, not only for daily necessities but also for special purposes. However, in many cases, it is difficult to satisfy mechanical strength, thermal or electrical properties even if the types of polymers are diversified by the polymer itself. In this case, the properties of the polymer are often strengthened by mixing the polymer and the filler, and various studies are being conducted on the polymer and the filler.

Among these, studies on polymers including thermally conductive fillers are actively conducted in order to improve the thermal conductivity of polymers, and through this, attempts to make plastic molded articles having more excellent thermal conductivity are continuing. Plastics with excellent thermal conductivity are most often used in electronic devices that generate heat, and are often used to rapidly dissipate heat and protect electronic devices. In addition, it can be applied in various ways when fast heat transfer is required among household items.

These thermally conductive fillers often use particles having a large aspect ratio due to their characteristics, and accordingly, there is a problem in that the thermal conductivity differs greatly depending on the direction of the thermally conductive filler. In particular, when a plastic product is molded along the flow direction, such as extrusion, there is a problem in that the difference in thermal conductivity according to the direction is large.

Republic of Korea Patent Publication No. 10-2014-0108405

An object of the present invention is to provide a thermally conductive plastic having excellent thermal conductivity.

Another object of the present invention is to provide a thermally conductive plastic having excellent mechanical strength.

Another object of the present invention is to provide a thermally conductive plastic having high thermal conductivity compared to the input amount of the thermally conductive filler with uniform thermal conductivity.

Thermally conductive plastic according to the present invention is a thermally conductive bead comprising a first thermally conductive filler having an aspect ratio of 30 or more on the surface;

a second thermally conductive filler having an aspect ratio of 3 to 20;

poly(acrylonitrile-butadiene-styrene) copolymers; and

polyolefin; and

In the thermally conductive plastic according to an embodiment of the present invention, the first thermally conductive filler may be a carbon-based thermally conductive filler.

In the thermally conductive plastic according to an embodiment of the present invention, the second thermally conductive filler may be boron nitride.

In the thermally conductive plastic according to an embodiment of the present invention, the thermally conductive plastic may further include a titanate-based coupling agent.

In the thermally conductive plastic according to an embodiment of the present invention, the thermally conductive plastic may further include maleic anhydride.

In the thermally conductive plastic according to an embodiment of the present invention, the thermally conductive plastic comprises 30 to 80 parts by weight of the thermally conductive bead, 20 to 70 parts by weight of the second thermally conductive filler, and 10 to 30 parts by weight of poly( Acrylonitrile-butadiene-styrene) copolymer may be included.

Thermally conductive plastic according to the present invention is a thermally conductive bead comprising a first thermally conductive filler having an aspect ratio of 30 or more on the surface; a second thermally conductive filler having an aspect ratio of 3 to 20; poly(acrylonitrile-butadiene-styrene) copolymers; and polyolefin; including excellent thermal conductivity, as well as excellent mechanical strength.

Advantages and features of embodiments of the present invention, and methods of achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

In describing the embodiments of the present invention, if it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

Thermally conductive plastic according to the present invention is a thermally conductive bead comprising a first thermally conductive filler having an aspect ratio of 30 or more on the surface; a second thermally conductive filler having an aspect ratio of 3 to 20; poly(acrylonitrile-butadiene-styrene) copolymers; and polyolefin;

The thermally conductive plastic according to the present invention simultaneously includes a first thermally conductive filler with a high aspect ratio and a second thermally conductive filler with a relatively low aspect ratio, thereby exhibiting significantly superior thermal conductivity compared to the case of including only one of them. .

Specifically, when a conventional thermally conductive filler having a high aspect ratio is introduced, a problem in which the directionality of the filler is formed due to the high aspect ratio in the process of extrusion, etc. occurred. However, the thermally conductive plastic according to the present invention is characterized in that the first thermally conductive filler having a high aspect ratio is distributed on the bead to prevent the problem of forming such a directionality, thereby minimizing the difference in thermal conductivity according to the heat transfer direction.

Furthermore, the thermally conductive plastic according to the present invention includes a second thermally conductive filler with a relatively low aspect ratio at the same time, thereby preventing a decrease in thermal conductivity that may occur due to distribution of the thermally conductive filler only on the bead and having a more uniform thermal conductivity. have.

As described above, the thermally conductive plastic according to the present invention includes thermally conductive beads formed on the surface of the first thermally conductive filler having a relatively large aspect ratio, thereby preventing a difference in thermal conductivity due to the formation of orientation of the thermally conductive filler during molding, Thermally conductive plastic has the characteristic of having uniform thermal conductivity even if the direction of heat transfer is different.

Specifically, the thermally conductive bead including the first thermally conductive filler on the surface may be a first thermally conductive bead attached to a conventional polymer bead, in which case the attachment of the first thermally conductive filler is attached using a coupling agent or The bead to which the thermally conductive filler is attached may be manufactured using an electrospray method, etc., but the present invention is not limited thereto.

In this case, the coupling agent may use a silane coupling agent or a titanate-based coupling agent to be described later, and preferably use a titanate-based coupling agent to improve adhesion.

The polymer bead can be used without limitation when the first thermally conductive bead is an attachable bead, and the present invention is not limited thereto. As a specific and non-limiting example, the polymer beads may be one or two or more selected from epoxy, acrylic, polyethylene, polypropylene and poly (acrylonitrile-butadiene-styrene) copolymers, preferably epoxy or acrylic beads. can

In the thermally conductive plastic according to the present invention, the first thermally conductive filler may be a carbon-based thermally conductive filler. More specifically, the carbon-based thermally conductive filler may be one or two or more selected from graphene, graphite, carbon nanotubes, graphite, and carbon black, and preferably one or two or more selected from graphene, graphite and carbon nanotubes. is available.

In the thermally conductive plastic according to an embodiment of the present invention, the thermally conductive beads may have an average particle diameter of 5 to 30 μm, and the advantage of forming a thermally conductive plastic with uniform physical properties while ensuring ease of molding by satisfying this range There is this.

The thermally conductive plastic according to an embodiment of the present invention may contain 30 to 80 parts by weight, preferably 40 to 70 parts by weight, of thermally conductive beads relative to 100 parts by weight of the polyolefin, and when a small amount of thermally conductive beads is included, thermal conductivity This lowering problem may occur, and when a large amount of thermally conductive beads is included, a problem of lowering impact strength and durability may occur.

The thermally conductive plastic according to the present invention includes a second thermally conductive filler that is directly mixed into the polyolefin substrate in addition to the thermally conductive beads, and in this case, the second thermally conductive filler may use a low aspect ratio of 3 to 20. As described above, when the thermally conductive beads are formed and mixed with polyolefin, the problem of orientation of the thermally conductive filler can be solved, but the problem of intensive gathering of the thermally conductive filler on the surface of the thermally conductive bead may occur, and the thermal conductivity according to the present invention The conductive plastic has solved this problem by further including a second thermally conductive filler.

In particular, by using a filler having a low aspect ratio as the second thermally conductive filler, there is an advantage in that it is possible to solve the problem caused by the mixing of thermally conductive beads while preventing the problem of orientation formation. Specifically, the second thermally conductive filler may be boron nitride, and there is an advantage in that thermal conductivity can be further improved by using boron nitride.

The thermally conductive plastic according to an embodiment of the present invention may use 20 to 70 parts by weight, preferably 30 to 60 parts by weight, of the second thermally conductive filler relative to 100 parts by weight of the polyolefin, and a small amount of the second thermally conductive filler In this case, thermal conductivity may be lowered, and when a large amount of the second thermally conductive filler is included, there may be a problem in that the durability of the thermally conductive plastic is deteriorated.

The thermally conductive plastic according to the present invention comprises a polyolefin and poly(acrylonitrile-butadiene-styrene) copolymer as a substrate. At this time, as the polyolefin, one or more selected from polyethylene, polypropylene, etc. may be used, and polypropylene may be preferably used.

In this case, the polyolefin may have a melt index of 10 to 25 g/10 min, and the poly(acrylonitrile-butadiene-styrene) copolymer may have a melt index of 35 to 50 g/10 min. By satisfying the above-described range, the thermally conductive plastic has high mechanical strength while ensuring moldability by injection or extrusion.

The thermally conductive plastic according to an embodiment of the present invention may include 10 to 30 parts by weight, preferably 15 to 25 parts by weight, of the poly(acrylonitrile-butadiene-styrene) copolymer, based on 100 parts by weight of the polyolefin. When a small amount of the (acrylonitrile-butadiene-styrene) copolymer is included, the mechanical strength improvement effect is insignificant, and when a large amount of the poly(acrylonitrile-butadiene-styrene) copolymer is included, compatibility with the thermally conductive filler degradation may occur.

The thermally conductive plastic according to an embodiment of the present invention may further include maleic anhydride, and by further including such maleic anhydride, the compatibility of the polyolefin and the poly(acrylonitrile-butadiene-styrene) copolymer is improved. can be further improved. The thermally conductive plastic according to an embodiment of the present invention may further contain 1 to 10 parts by weight of maleic anhydride relative to 100 parts by weight of the polyolefin, and when a small amount of maleic anhydride is included, compatibility between polymer substrates may decrease. And, if a large amount of maleic anhydride is included, a decrease in mechanical strength may occur.

The thermally conductive plastic according to an embodiment of the present invention may further include a titanate-based coupling agent. By further including such a titanate-based coupling agent, it has a characteristic of exhibiting an excellent compatibility improvement effect compared to the case of using a conventional silane coupling agent. It has the advantage of being strong.

In the thermally conductive plastic according to an embodiment of the present invention, the titanate-based coupling agent is preferably Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris neodecanoato-O; Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, iris(dodecyl)benzenesulfonato-O; Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris(dioctyl)phosphato-O; Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris(dioctyl)pyrophosphato-O; Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris(2-ethylenediamino)ethylato; And Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris(3-amino)phenylato may be one or two or more selected from, and by using such a titanate-based coupling agent, even with a small amount of coupling agent, It has the advantage of excellent dispersibility improvement effect.

The thermally conductive plastic according to an embodiment of the present invention may contain 2 to 20 parts by weight, preferably 3 to 10 parts by weight of the titanate-based coupling agent, based on 100 parts by weight of the polyolefin, and a small amount of the titanate-based coupling agent. In this case, compatibility may decrease, and if a large amount of titanate-based coupling agent is included, problems such as decrease in mechanical strength may occur.

Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples. The examples below are only for helping understanding of the present invention, and the scope of the present invention is not limited by the examples below.

[Production Example 1]

1. Preparation of thermally conductive beads

As the first thermally conductive filler, 10 g of graphite having an aspect ratio of about 7,000 was mixed with 150 g of water, and 40 g of polyvinyl alcohol having a molecular weight of about 20,000 and 50 g of acrylic beads having an average particle diameter of 40 μm were added to uniformly After mixing, they were granulated using an electrospray method, and then dried at 30° C. for 12 hours to prepare thermally conductive beads. At this time, the electrospray method was set to a discharge rate of 0.012 ㎖/min, an applied voltage of 20 kV, and a nozzle diameter of 20G.

2. Manufacture of thermally conductive plastics

Polypropylene having a melt index of 18 g/10 min (hereinafter referred to as PP), a poly(acrylonitrile-butadiene-styrene) copolymer having a melt index of 43.0 g/10 min (hereinafter referred to as ABS), the prepared thermally conductive beads, As the second thermally conductive filler, titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris neodecanoato-O, which is a coupling agent based on boron nitride, maleic anhydride, and titanate, having an aspect ratio of about 17 and a diameter of about 3 mm After mixing and blending in the ratio of Table 1, it was injected into an extruder to prepare a thermally conductive plastic having a thickness of 10 mm through melt extrusion.

[Preparation Examples 2 to 9]

It was prepared in the same manner as in Preparation Example 1, but mixed with the composition shown in Table 1 below to prepare a thermally conductive plastic. However, in Preparation Example 9, instead of the titanate-based coupling agent, a silane coupling agent of 3-aminopropyltriethoxysilane was added in 5 parts by weight based on 100 parts by weight of polypropylene to prepare a thermally conductive plastic.

production example pp ABS thermally conductive beads boron nitride titanate coupling agent maleic anhydride One 100 20 50 40 5 3 2 100 22 45 37 5 3 3 100 7 50 40 5 3 4 100 35 50 40 5 3 5 100 20 50 0 5 3 6 100 20 25 40 5 3 7 100 20 90 40 5 3 8 100 20 50 40 0 3 9 100 20 50 40 0 3

Measurement of thermal conductivity according to the direction of heat transfer

First, prepare a specimen with a thickness of 10 mm in an extruder (direction 1), and separately perform extrusion to a thickness of 100 mm according to each composition of Preparation Example, then cut a section to a thickness of 10 mm to prepare a specimen (direction 2) In accordance with ASTM E 1530, the thermal conductivity was measured in each direction, and the results are shown in Table 2.

strength measurement

The flexural strength of each specimen was measured according to ASTM D 790, and the results are shown in Table 2.

production example Thermal conductivity (W/m·K) Flexural strength (MPa) direction 1 direction 2 One 33.8 30.6 53 2 34.2 31.1 52 3 31.5 27.8 37 4 27.4 22.7 51 5 20.6 15.4 46 6 19.8 12.2 48 7 34.5 31.0 39 8 22.7 14.9 33 9 23.5 18.3 37

Referring to Table 2, it can be seen that the thermally conductive plastics of Preparation Examples 1 and 2 have insignificant differences in thermal conductivity according to directions and have high flexural strength. In addition, in the case of Preparation Examples 8 and 9 in which the titanate-based coupling agent was not used, it was determined that the simultaneous decrease in thermal conductivity and flexural strength occurred due to a decrease in compatibility.

Claims (6)

Thermally conductive beads comprising a first thermally conductive filler having an aspect ratio of 30 or more on the surface;
a second thermally conductive filler having an aspect ratio of 3 to 20;
poly(acrylonitrile-butadiene-styrene) copolymers; and
Polyolefin; Thermally conductive plastic containing. The method of claim 1,
The first thermally conductive filler is a thermally conductive plastic, characterized in that the carbon-based thermally conductive filler. The method of claim 1,
The second thermally conductive filler is a thermally conductive plastic, characterized in that boron nitride. The method of claim 1,
The thermally conductive plastic further comprises a titanate-based coupling agent. The method of claim 1,
The thermally conductive plastic is thermally conductive plastic, characterized in that it further comprises maleic anhydride. The method of claim 1,
The thermally conductive plastic includes 30 to 80 parts by weight of a thermally conductive bead, 20 to 70 parts by weight of a second thermally conductive filler, and 10 to 30 parts by weight of a poly(acrylonitrile-butadiene-styrene) copolymer based on 100 parts by weight of the polyolefin. Thermally conductive plastic, characterized in that.