KR101673599B1 - Manufacturing method of Polymer Nanocomposites containing Carbonnanotube and Nanoclay - Google Patents

Abstract

The present invention relates to a method for producing a polymer nanocomposite containing a carbon nanotube and a nanoclay, and more particularly, to a method for producing a nanoclay comprising a carbon nanotube dispersed in a matrix polymer by a high shear dispersion method, The present invention also relates to a method for producing a polymer nanocomposite in which two nanomaterials are uniformly and stably dispersed in the same matrix resin. According to the method for producing a polymer nanocomposite of the present invention, effective simultaneous dispersion of nanoparticles is induced without a pretreatment step for improving the dispersibility of carbon nanotubes or nano-clays, and excellent heat resistance and mechanical strength Can be manufactured. The polymer nanocomposite thus prepared can be applied to plastic parts such as automobile interior and exterior materials, building materials, and the like.

Description

Technical Field [0001] The present invention relates to a method for producing a polymer nanocomposite containing carbon nanotubes and a nanoclay,

The present invention relates to a method for producing a polymer nanocomposite containing both carbon nanotubes and nanoclays at the same time. According to the manufacturing method of the present invention, a polymer having excellent heat resistance and mechanical properties without a pretreatment process for dispersing carbon nanotubes and nano- Nanocomposites can be manufactured, and the produced polymer nanocomposite can be usefully applied to automobile interior and exterior materials, parts, and building interior materials.

Currently, the research direction of automobile technology focuses on improvement of fuel efficiency, emission reduction of pollutants and recycling of parts as a way to solve environmental problems. Therefore, in the field of automotive materials, researches have been actively carried out to improve the fuel efficiency of a vehicle by reducing the weight of the vehicle by developing a polymer composite excellent in dimensional stability, mechanical properties and heat resistance. In particular, polymer nanocomposites have recently been emerging as a method to improve weight and recyclability while maintaining improved physical properties of conventional polymer composites, and various approaches have been proposed.

Carbon nanotubes are carbon nanotubes, long-barrel nano-diameters, which are 1000 times more conductive than copper and have high strength and elastic modulus that is 100 times that of steel. Carbon nanotubes are used in applications such as electric / electronic products and automobile fields to realize high performance, light weight and miniaturization by combining with existing materials. In particular, it has been attracting attention as a polymer composite exhibiting a high aspect ratio with respect to a length-to-diameter ratio and showing a high rigidity with respect to the same weight.

Meanwhile, nanoclay composites, which were the main research subjects of polymer nanocomposites before the discovery of nanotubes, showed excellent thermal and mechanical properties, even though they contain a lower ratio of inorganic materials than conventional composites It has received much attention because of it. Nano-clay is also a nano-inorganic particle with a high aspect ratio, which has the advantage of improving heat resistance, gas barrier properties and mechanical strength of a composite material.

Therefore, it is expected that lightweight composites with the advantages of both materials can be produced by mixing the two nanomaterials to produce a composite material. However, carbon nanotubes are agglomerated by interfacial entanglement at the ㎛ level and surface attraction such as van der Waals force at nm level in the manufacturing process of the composite, There is a problem that a large amount is added to maintain the characteristics of the existing composite material by providing a cause of deteriorating the properties of the composite material. Also, there is a problem that the nanoclay is difficult to disperse in a polymer matrix that is lipophilic due to high van der Waals energy and hydrophilic surface between the layers. A general method of introducing nano-clay into a polymer is to insert a low-molecular-weight organic agent between the layered structures between the clay layers, but there is still a limit in dispersing the clay in the polymer having a high viscosity.

In Japanese Unexamined Patent Publication (Kokai) No. 5, pp. 393 to 499, a polystyrene composite material in which carbon nanotubes and nano clays are dispersed in an emulsion state of polystyrene is disclosed. However, The dispersion of the clay was not good and the effect of improving the physical properties by the addition of the nanoclay was not satisfied. Korean Patent No. 10-0706652 discloses a thermoplastic resin composition comprising a carbon nanotube and an organically treated nano clay. Korean Patent No. 10-0860828 discloses a nano-clay and carbon obtained by introducing a polar group onto the surface Nanomaterials, and nanotubes. However, the above-described techniques have a problem in that a pretreatment process is required, such as physical or chemical treatment for organic treatment or polar group introduction. Korean Patent No. 10-0827861 discloses a method for producing a nanocomposite by mixing carbon nanotubes and graphite nanoparticles, but does not show the property of improving the physical properties.

As a result, the present inventors have found that when dispersing carbon nanotubes and nanoclays in a matrix polymer resin, the particles are dispersed by applying a high shear force of not less than 2000 rpm rather than a usual shear force of about 600 rpm, The dispersing force is increased because the matrix polymer is permeated and the matrix polymer is separated therebetween. In addition, the nano-clay existing in the layered form is separated by the high shear force to cause the interval between the layers, It has been found that the polymer nanocomposite having excellent heat resistance and mechanical strength can be manufactured because it is difficult to aggregate the nanoclay particles when the already dispersed carbon nanotube enters between the layers.

Accordingly, it is an object of the present invention to provide a method for producing a polymer nanocomposite containing both carbon nanotubes and nanoclay without a pretreatment process.

According to the present invention,

A first step of melt-mixing the carbon nanotubes with the matrix polymer to prepare a carbon nanotube mixture;

 A second step of high-shear molding the carbon nanotube mixture to produce a carbon nanotube composite material;

A third step of preparing a nanoclay mixture by melt-mixing the carbon nanotube composite material and the nanoclay; And

A fourth step of high-shear molding the nanoclay mixture to produce a carbon nanotube-nanoclay composite material;

The present invention also provides a method for producing a polymer nanocomposite material.

According to the method for producing a polymer nanocomposite of the present invention, effective simultaneous dispersion of nanoparticles in a matrix resin is induced without a pretreatment step for improving the dispersibility of carbon nanotubes or nano-clay, And a carbon nanotube-nanoclay composite material having mechanical strength can be produced. In addition, the prepared polymer nanocomposites can be replaced with existing polymer-talc composites, polymer-glass fiber composites, and polymer-nano-clay composites, which can reduce the weight of automobile interior and exterior plastic parts and require various building materials and physical properties It is useful for plastic parts.

FIG. 1 is a diagram illustrating a process for producing the polymer nanocomposite of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for producing a novel polymer nanocomposite which effectively disperses carbon nanotubes and nanoclays simultaneously in a polymer matrix by using a high shear method, comprising the steps of mixing carbon nanotubes with a polymer and dispersing them in a high- Adding the nanoclay to the carbon nanotube polymer dispersion and dispersing it in a high shear method.

In the first step of preparing a mixture of carbon nanotubes by melt-mixing the carbon nanotubes with a matrix polymer, the carbon nanotubes may be single wall carbon nanotubes (SWNTs), double wall carbon nanotubes (DWNTs) (MWNT) may be used. As the matrix polymer, at least one selected from polyolefins such as polyethylene, polypropylene, polyethylene ether phthalate and epoxy resin, and elastomers such as polyamide and polyimide may be used, and polypropylene is preferably used. The polypropylene resin may be a propylene homopolymer, a random copolymer, a block copolymer, or a mixture thereof. It is preferable that the matrix polymer has a melt index (MI) of 0.5 to 30 g / 10 min (ASTM D 1238, 230 ° C). If the melt index is less than 0.5 g / 10 min, Problems may occur, and if it exceeds 30 g / 10 min, the mechanical properties of the final product may deteriorate due to excessive melt flowability.

In the process of preparing the carbon nanotube mixture, a compatibilizer may be further added to improve the dispersibility of the carbon nanotube. As such a compatibilizer, a polypropylene resin containing maleic anhydride graft polypropylene, a carboxy group and a hydroxyl group can be used, and it is preferable to use maleic anhydride graft polypropylene. In this case, the weight ratio of the carbon nanotubes to the compatibilizing agent is preferably in the range of 3: 7 to 7: 3. When the content of the compatibilizing agent is excessively large, the carbon nanotubes are effectively dispersed, On the contrary, when the amount is too small, it is difficult to expect a sufficient dispersion effect by the addition of the compatibilizing agent.

When the melt is mixed, the temperature is preferably 180 to 240 ° C. If the temperature is less than 180 ° C., the matrix polymer may not sufficiently melt and may not be uniformly mixed with the carbon nanotubes. When the temperature exceeds 240 ° C., The mechanical properties of the nanocomposite may be deteriorated. In this case, since the shear rate is 10 to 100 rpm, the influence of the thermal history can be neglected in contrast to the high-speed stage.

In the second step of high-shear molding the carbon nanotube mixture to prepare the carbon nanotube composite, the carbon nanotube mixture is injected into the high-end end screw. The resin injected into the screw causes shear deformation due to the pressure difference between the upper part of the screw and the lower part of the screw. This is referred to as a shear flow field, and a shear flow of 2000 to 5000 rpm is applied to the shear flow field, -shear) can be generated. In such a high shear condition, the intergranular separation of the carbon nanotubes takes place, and the dispersing force is increased because the matrix polymer penetrates and disperses. If the shear rate is less than 2000 rpm, the shear deformation may not occur due to the small pressure difference between the upper part of the screw and the lower part of the screw. Even if the shear rate exceeds 5000 rpm, . At this time, the temperature of the high-end portion is maintained at 180 to 240 ° C, the same as the melt-mixing temperature.

In the third step of preparing the nano-clay mixture by melt-mixing the carbon nanotube composite material and the nano-clay, the nano-clay is formed of montmorillonite, hectorite, vermiculite, At least one selected from the group consisting of saponite, sauconite, magadiite, kenyaite, kaolinite and thuringgite can be used. In the present invention, the nano-clay may be used in a non-emulsified state, or may be an organic compound containing at least one selected from the group consisting of octylammonium, decylammonium, dodecylammonium, hexadecylammonium, octadecylammonium and dimethylhydrogenated tallowammonium May be used.

In the preparation of the nanoclay mixture, a composition comprising 50 to 65 wt% of a matrix polymer, 25 to 45 wt% of the carbon nanotube composite material, and 1 to 10 wt% of a nano clay is heated at a temperature of 180 to 240 DEG C , And melt mixing at a shear rate of 10 to 100 rpm. In this case, the total content of the carbon nanotubes and the nanoclays in the final polymer nanocomposite is preferably adjusted to 1 to 15% by weight. When the content is less than 1% by weight, the effect of improving the physical properties is insignificant. The specific gravity of the composition is increased and it is difficult to reduce the weight, which is disadvantageous from the viewpoint of economy.

In addition, as in step 1 above, a compatibilizing agent such as maleic anhydride graft polypropylene may be further added to improve the dispersibility of the nanoclay when the nanoclay is added.

The temperature and shear rate in the fourth step of producing the carbon nanotube-nanoclay composite by high shear molding of the nanoclay mixture are the same as those in the second step, and the nanoclay mixture is present in a layer form during high- Layer separation of the nanoclays occurs, and the gap between the layers spreads and dispersion occurs in the matrix polymer. At this time, the carbon nanotubes already dispersed in the polymer are inserted between the layers to prevent aggregation of the nanoclay particles. In particular, carbon nanotubes have a hydrophobic surface, which stably maintains the layer of nanoclay without aggregation with the hydrophilic nanoclay surface. In addition, the dispersed carbon nanotubes are also prevented from re-aggregating between particles by the nanoclay layer.

The polymer nanocomposite of the present invention may further contain various additives such as an antioxidant, a colorant, a release agent, a lubricant, a light stabilizer, etc., and the amount of the additives to be used may be suitably adjusted according to various factors including desired end use and characteristics .

According to the method for producing a polymer nanocomposite of the present invention, effective simultaneous dispersion of nanoparticles is induced without a pretreatment step for improving the dispersibility of carbon nanotubes or nano-clays, and excellent heat resistance and mechanical strength Can be manufactured. The polymer nanocomposite thus prepared can be applied to plastic parts such as automobile interior and exterior materials, building materials, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

[Example]

Example: Preparation of Carbon Nanotube-Nanoclay Composites

97.3% by weight of a polypropylene random copolymer resin (R724J, GS Caltex) and 2.7% by weight of dried multi-walled carbon nanotubes (Nanocyl, Belgium) were uniformly mixed for 10 minutes at a melting temperature of 180 DEG C and 50 rpm To prepare a carbon nanotube mixture. Carbon nanotube composites were prepared by injecting a mixture of carbon nanotubes into the high end and applying a shear rate to the shear flow field at 2000 rpm. 38% by weight of the carbon nanotube composite material, 60% by weight of polypropylene random copolymer resin and 2% by weight of nano clay (montmorillonite, Cloisite 20A, USA) were added to the plasticizer, For 10 minutes to prepare a nanoclay mixture. The nanoclay mixture was injected into the high-shear end and the shear rate was applied again at 2000 rpm to prepare a carbon nanotube-nanoclay composite.

Comparative Example 1: Production of polypropylene resin with shear applied

The polypropylene random copolymer resin was subjected to shearing at a shear rate of 2000 rpm to prepare a polypropylene resin having a shearing action.

Comparative Example 2: Production of carbon nanotube composite material

97% by weight of polypropylene random copolymer resin and 3% by weight of multi-walled carbon nanotubes (Nanocyl, Belgium) were uniformly mixed for 10 minutes at a melting temperature of 180 DEG C and 50 rpm for 10 minutes, The carbon nanotube composite material was prepared by applying a shear rate to the flow field at 2000 rpm.

Comparative Example 3: Preparation of nanoclay composite

The nanoclay composite was prepared in the same manner as in Comparative Example 2 except that the multiwall carbon nanotubes were replaced with nano clay (montmorillonite, Cloisite 20A, Southern Clay Products Inc., USA).

Property measurement test

In order to measure the mechanical properties of the composite material and the polypropylene resin prepared in the above Examples and Comparative Examples 1 to 3, the specimens were molded according to the following physical properties measurement methods through injection molding, And the results are shown in Table 1. < tb >< TABLE > Here, the tensile property measurement specimen is a dumbbell-shaped specimen, and the impact strength specimen is a specimen having a notch formed on the specimen.

1) Measurement of tensile properties

Tensile Strength and Young Modulus values were measured using a universal testing machine (Instron 4467) by making test specimens according to ASTM D 638.

2) Method of measuring impact strength

A test specimen was prepared in accordance with ASTM D 256, and the impact strength value was measured using an Izod impactor (TINIUS OLSEN 892).

Test Items unit Comparative Example 1
PP Comparative Example 2
PP / CNT
(3% by weight) Comparative Example 3
PP / clay
(3% by weight) Example
PP / CNT / clay
(3% by weight) The tensile strength Mpa 28.2 36 28.55 36.13 Young's modulus MPa 1280 1795 1588 2250 Impact strength kJ / m ² 2.4 3.0 5.55 6.28

As shown in Table 1, the composite material of Comparative Example 2 in which the carbon nanotubes were added to the polypropylene resin had excellent tensile strength characteristics, and in Comparative Example 3 in which nanoclays were added, the impact strength was greatly improved Can be seen. The composite material prepared in the example of the present invention in which carbon nanotubes and nanoclays were dispersed through a high shear stage exhibited both the effect of addition of two reinforcing agents, and thus, both the tensile strength and the impact strength were excellent. Also, it shows that the Young's modulus synergy effect is excellent and shows excellent elastic characteristics.

As a result, according to the method for producing a polymer nanocomposite of the present invention in which two nanomaterials are simultaneously added by a high shear dispersion method, a composite material having excellent mechanical strength can be produced. The produced polymer nanocomposite can be used for automobile interior and exterior materials, It can be confirmed that it can be applied.

Claims (6)

A first step of melt-mixing the carbon nanotubes with the matrix polymer to prepare a carbon nanotube mixture;
A second step of forming the carbon nanotube composite by molding the carbon nanotube mixture at a shear rate of 2000 to 5000 rpm;
A third step of preparing a nanoclay mixture by melt-mixing the carbon nanotube composite material and the nanoclay; And
A fourth step of preparing the carbon nanotube-nanoclay composite by molding the nanoclay mixture at a temperature of 180 to 240 DEG C and a shear rate of 2000 to 5000 rpm;
Wherein the polymeric nanocomposite material is a polymeric nanocomposite material.
The method of claim 1, wherein the carbon nanotubes are at least one selected from single wall carbon nanotubes (SWNTs), double wall carbon nanotubes (DWNTs), and multiwall carbon nanotubes (MWNTs) Way.
The method for producing a polymer nanocomposite material according to claim 1, wherein the matrix polymer is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene ether phthalate, epoxy resin, polyamide and polyimide.
The method of claim 1, wherein the nanoclay is selected from the group consisting of montmorillonite, hectorite, vermiculite, saponite, sauconite, magadiite, kenyaite, ), Kaolinite, and thuringgite. The method for producing a polymer nanocomposite according to claim 1,
delete The method of claim 1, wherein the total content of the carbon nanotube and the nano-clay in the polymer nanocomposite is 1 to 15 wt%.

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