KR102273847B1 - Polymer Composite with Superior Mechanical Strength and Electrical Conductivity, Preparing Method Thereof and Agitator Used for Preparing the Same - Google Patents

Abstract

The present invention provides a method for manufacturing a polymer composite material in which carbon nanotubes are dispersed in a polymer and a polymer composite material manufactured by the method. The manufacturing method according to the present invention comprises the steps of: preparing a solid-state monomer and a solid-state carbon nanotube; manufacturing a raw material mixture in a solid state by mixing and dispersing the monomer and carbon nanotubes; and polymerizing the raw material mixture.

Description

Polymer Composite with Superior Mechanical Strength and Electrical Conductivity, Preparing Method Thereof and Agitator Used for Preparing the Same

The present invention relates to a polymer composite material having excellent mechanical strength and electrical conductivity, a method for manufacturing the same, and a stirrer used for manufacturing the same.

Polymer materials exhibit unique mechanical, electrical, and thermal properties according to their basic monomer and chemical structure. Although the properties of a pure polymer material exhibit a certain range, it is possible to improve various properties by adding reinforcement. A form in which a solid reinforcing material, that is, a filler, is dispersed using a polymer material as a matrix is called a polymer composite material.

An example of a polymer material is nylon, and in particular, monomer cast nylon (MC nylon) (hereinafter abbreviated as 'MC nylon') is a kind of engineering plastic, manufactured by catalyzing a chemical component to caprolactam. It is a crystalline polymer. MC nylon has a molecular weight of about 10 times or more and a crystallinity of about 2 times or more compared to conventional nylon-6, and is in the spotlight as a material that can be used in various industrial fields based on very excellent mechanical strength.

However, MC nylon, which is electrically insulating, has no static-removing function, that is, no static-static function. For this reason, MC nylon is used as equipment for the manufacturing process or assembly process of precision electronic products that can be fatally damaged by fine spikes caused by static electricity such as PCB, LCD, etc., for example, a bogie wheel, work tool, transport pallet, etc. is limited in that it cannot be used. Thus, efforts are being made to impart at least a semiconductor level of electrical conductivity (volume resistivity of about 106 Ω·cm) to MC nylon.

As a method of imparting a predetermined electrical conductivity to MC nylon, there is a method of adding carbon black, graphite, etc., which are carbon-based materials, when melt casting a monomer such as caprolactam. However, MC nylons prepared by adding carbon black or graphite generally have somewhat lowered mechanical strength.

In the case of carbon black, it is not dispersed well because of its large specific surface area, and it is present in the form of paste by adsorbing a large amount of raw material monomers, thereby hindering polymerization. As a result, the manufactured MC nylon has a significant deterioration in properties, and electrical conductivity also has a problem in that it does not reach a desired level, that is, a semiconductor level.

Although graphite is relatively well dispersed compared to carbon black, it nevertheless tends to settle in molten monomers or polymers in molten form and is not easily dispersed. Graphite must also be used in large amounts (at least 5% by weight of the total weight of MC nylon) to give the MC nylon a desired level of electrical conductivity, which may lead to a decrease in the mechanical strength of the MC nylon, particularly a decrease in abrasion resistance.

Therefore, in order to solve this problem, the use of carbon nanotubes having superior mechanical strength as well as electrical conductivity as well as thermal conductivity is attracting attention compared to the two carbon-based materials described above.

Such carbon nanotubes can impart a predetermined electrical conductivity to MC nylon while greatly improving its mechanical strength, particularly abrasion resistance. In general, the abrasion resistance of MC nylon is not superior to that of other engineering polymers, so the compounding with carbon nanotubes is expected to greatly expand the industrial application range of MC nylon.

However, carbon nanotubes are easily entangled and agglomerated by themselves as fibrous materials, and thus the desired level of dispersion is not achieved no matter how pulverized/mixed/stirred in the molten monomer or molten polymer containing carbon nanotubes.

If polymerization is performed in this state, there is a high possibility that polymerization is not easily performed in the portion where the carbon nanotubes are biased.

Even after polymerization is completed, if the carbon nanotubes are not sufficiently dispersed, the effect of improving the mechanical strength may be insignificant or absent, and in some cases, the mechanical strength may be reduced in the portion where the carbon nanotubes are biased. In addition, it may be possible that only a portion of the MC nylon exhibits electrical conductivity, or it may not be possible to achieve the desired electrical conductivity in terms of the overall product.

On the other hand, carbon nanotubes biased on the other hand may bloom during work in an environment such as a clean room, causing a secondary problem of contaminating the clean room workplace.

If only the above problems are solved, the composite material made of MC nylon and carbon nanotubes has not only excellent mechanical strength but also electrical conductivity at the semiconductor level, so it can be used as an all-weather engineering material applicable to various industrial fields requiring these properties. There will be.

Therefore, the present invention provides a novel manufacturing method capable of solving the above-mentioned problems and a composite material manufactured by the same, in which predetermined electrical conductivity and excellent mechanical strength are compatible, as well as a structure specialized for the manufacturing method of the present invention Agitator is provided.

According to one aspect of the present invention, there is provided a method for manufacturing a polymer composite material, for example, a composite material of carbon nanotubes and MC nylon.

The manufacturing method of the present invention has one feature in that a solid-state raw material mixture is first prepared by mixing and dispersing a solid-state monomer and a solid-state carbon nanotube at a predetermined time and speed in a stirrer having a specific structure. This feature of the present invention can significantly improve the problem that carbon nanotubes are not easily dispersed in the conventional molten monomer or polymer in a molten form.

According to one aspect of the present invention, the present invention provides a polymer composite material manufactured by the above manufacturing method, specifically, a polymer composite material that is a carbon nanotube-containing monomer cast nylon.

The polymer composite material of the present invention has very good mechanical strength, in particular, superior abrasion resistance compared to conventional MC nylon, and at the same time has electrical conductivity at a level usable as a material for equipment in the electronics industry.

According to one aspect of the present invention, the present invention provides a stirrer having a specialized structure that can very effectively disperse the solid-state monomer and carbon nanotubes.

Such a stirrer can induce the dispersion mechanism described above repeatedly for a predetermined time to very effectively disperse the carbon nanotubes in the monomer.

By the above aspects, the present invention can significantly solve the above-mentioned conventional technical problems, the technical basis of the present invention for achieving this will be described in detail below.

Manufacturing method and polymer composite material

In one embodiment, the present invention provides a method for producing a polymer composite material in which carbon nanotubes are dispersed in a polymer.

The manufacturing method according to the present invention,

Preparing a solid-state monomer and solid-state carbon nanotubes;

preparing a raw material mixture in a solid state by mixing and dispersing the monomer and carbon nanotubes; and

Polymerizing the raw material mixture may be included.

In one specific example, in the step of preparing the raw material mixture in a solid state, the monomer in a solid state and the carbon nanotubes in a solid state may be added to a stirrer to mix and disperse.

The manufacturing method according to the present invention is characterized in that a solid-state raw material mixture is first prepared by mixing and dispersing a solid-state monomer and a solid-state carbon nanotube at a predetermined time and speed. This feature of the present invention can significantly improve the problem that carbon nanotubes are not easily dispersed in the conventional molten monomer or polymer in a molten form.

Specifically, in the method according to the present invention, mixing and dispersion of carbon nanotubes is induced in the solid-state monomer, and at this time, the so-called agglomerated phase, in which the carbon nanotubes are aggregated or entangled, is a small unit (length: 10~ 200 μm; 7-20 nm in diameter) and can be easily segmented. This is considered to be because the carbon nanotubes are not in a wet state.

For example, in carbon nanotubes, fine fiber strands are agglomerated and entangled, and they exist in a so-called sponge-like wet state in the melt. In this state, the fiber strands are not easily segmented into small units and tend to continue to aggregate. This is presumed to be the main reason that carbon nanotubes were hardly dispersed in the conventional molten monomer.

On the other hand, in the present invention, based on the above-described characteristics, fiber strands can be easily segmented, which is a major feature that carbon nanotubes can be better dispersed.

In the manufacturing method of the present invention, the dispersion mechanism is, as described above, that small units of well-segmented carbon nanotubes are scattered throughout the monomer while scattered in the stirrer, and some small units are, for example, by the driving force of the stirrer impeller. It is adsorbed or desorbed by solid monomer powder particles while moving between the monomers in a random direction regardless of up, down and left or right.

If this dispersion mechanism is repeatedly performed, it is possible to disperse carbon nanotubes that are not easily dispersed, that is, difficult to disperse, to a desired level.

In order to optimally perform this dispersion mechanism, it is important to determine the time and at what rate to induce the movement of carbon nanotubes repeatedly. The present invention provides optimal conditions for achieving this.

In one specific example, the mixing and dispersing is performed at room temperature, and may be performed in the range of 50 to 700 rpm in the stirrer.

In some cases, mixing and dispersion may be performed while variably changing the rpm within the rpm range, and in this case, it may be divided into two or more different rpm sections falling within the range. In addition, the increase/decrease of rpm in each arbitrarily divided section may be changed according to the situation, or alternatively, it may be performed by fixing the rpm to an arbitrary rpm selected in each section.

In one example for this, a preliminary mixing and dispersing step is performed in the range of 50 to 100 rpm, specifically in the range of 50 to 70 rpm, followed by mixing in the range of 100 to 700 rpm, specifically 200 to 700 rpm. and dispersion.

The mixing and dispersing step is performed in the rpm range for 6 hours or more, specifically 7 hours or more, and more specifically 9 hours or more, but may be performed for 10 hours or less.

In the present invention, in dividing the mixing and dispersing step into several steps, the preliminary mixing and dispersing step may be performed for 0.5 to 1.5 hours, and the subsequent intensive mixing and dispersing step may be performed for 4 to 10 hours .

More specifically, in dividing the mixing and dispersing step into three steps, the first step may be performed at a relatively low rpm for 0.5 hour to 1 hour, preferably for 1 hour. The second step may be performed at a relatively higher rpm than the preceding step for 0.5 hour to 1 hour, preferably for 1 hour. The final third step may be performed at a higher rpm compared to the previous step in order to suppress the aggregation of the segmented carbon nanotubes as much as possible while rapidly dispersing the carbon nanotubes segmented in the previous step. In addition, it can be carried out for a sufficient time to segment the inevitably formed agglomerated phase into small units again and disperse it throughout the stirrer, specifically at least 4 hours and at most 7 hours.

In one specific example in relation to the above, the mixing and dispersing are

A first stirring performed in the stirrer at room temperature at 50 to 80 rpm for 30 minutes to 1 hour;

a second stirring performed for 30 minutes to 2 hours at 100 to 300 rpm in the stirrer at room temperature; and

In the stirrer at room temperature, the third stirring may be performed at 200 to 700 rpm for 4 hours or more.

In general, since carbon nanotubes have a strong tendency to become entangled or agglomerate, it is not possible to completely suppress the generation of agglomerated phases of carbon nanotubes even by performing typical mixing and dispersing as known in the prior art. It is not well dispersed. However, surprisingly, when the mixing and dispersing steps of the solid-state monomer and carbon nanotubes are performed according to the subdivided steps of the present invention as previously taught, that is, the mixing and dispersing sections are divided, but at an rpm suitable for each section. Dispersion as intended by the present invention can be achieved when the stirring time is met. This is presumed to be because the granular mixing and dispersing step according to the present invention and the optimized rpm and stirring time are combined to form an agglomerated phase, which is again segmented and dispersed into small units.

In another aspect, it may be difficult to achieve a desired level of dispersion by performing the mixing and dispersing step for a rather short time, which is out of the preferred scope of the present invention, and it may be difficult to control the cycle of generation and fragmentation of the inevitably generated aggregated phase. Executing the mixing and dispersing steps for too long can also make it difficult to control the cycle of aggregated phase formation and fragmentation.

In one specific example, before polymerizing the raw material mixture, the method may further include heating and melting the raw material mixture in a solid state.

At this time, the raw material mixture in the solid state in a vacuum or dry nitrogen stream so that the moisture content is 0.01% by weight or less It is heated to 70°C to 130°C, specifically 70°C to 110°C, and melted by heating for 10 to 60 minutes, and moisture in the raw material mixture is removed. If the moisture of the raw material mixture is not sufficiently removed, the basic catalyst and moisture react in the polymerization process and there is a risk of explosion, and the reaction efficiency may be reduced.

In one specific example, the method may further include dividing the molten raw material mixture and distributing it to n different containers, stirring each, and then combining them again and stirring again. In this stirring step, carbon nanotubes may be further dispersed.

In one specific example, before polymerizing the raw material mixture, the method may further include adding and mixing a polymerization inducing additive to the molten raw material mixture, in this step, adding the polymerization inducing additive and 90 It can be mixed for 10 to 60 minutes at 40 to 80 rpm at ℃ to 110 ℃.

The polymerization inducing additive may include 0.4 to 0.6 parts by weight of a diisocyanate-based polymerization initiator based on 100 parts by weight of the monomer and 0.2 to 0.3 parts by weight of a basic catalyst based on 100 parts by weight of the monomer.

The diisocyanate-based polymerization initiator is not particularly limited, and specifically, may be hexamethylene diisocyanate or toluene diisocyanate.

The basic catalyst may be an alkali and/or alkaline earth metal, the alkali metal may be, for example, one or more selected from the group consisting of lithium, sodium and potassium, and the alkaline earth metal is, for example, calcium, magnesium, barium, It may be at least one selected from the group consisting of strontium, beryllium and radium.

In one specific example, the polymerization may be to put the molten raw material mixture into a mold heated to a temperature of 160 ° C. to 170 ° C. and polymerize for 30 to 60 minutes.

In one specific example, the raw material mixture may include 0.1 parts by weight to 2.5 parts by weight of carbon nanotubes based on 100 parts by weight of the monomer.

When the content of the carbon nanotubes exceeds the above range, polymerization may not be performed, and when the content of the carbon nanotubes is lower than the above range, both mechanical strength and electrical conductivity of the polymer composite material may be relatively deteriorated, which is not preferable.

In one specific example, the monomer is in a solid state at room temperature, and may include an amide functional group in its molecular structure.

In one specific example, the monomer may be caprolactam or lauryl lactam, specifically caprolactam.

In one embodiment, the present invention provides a polymer composite material prepared by the above manufacturing method, wherein the polymer composite material may be a carbon nanotube-containing monomer cast nylon.

Such a polymer composite material may satisfy all of the following physical properties:

- tensile strength of 800 kg/cm ^{2 or more;}

- more than 20% elongation;

- flexural strength of 1,100 kg/cm ^{2 or more;}

- a flexural modulus of at least 30,000 kg/cm ^{2 ;}

- Impact strength of 4.0 kgf.cm/cm or more;

- Thermal deformation temperature above 175℃

- ^{Volume resistivity of 10e 3} Ω·cm or more;

- wear rate of 0.07% by weight or less.

The wear rate was calculated by using a grinding stone from CALIBRADE H-18 of TABER INDUSTRIES in the United States to produce a carbon nanotube-polyamide composite material as an 80x80x50mm specimen, and grind the specimen 2000 times at 70 rpm under a load of 1 kg to obtain a carbon nanotube- It can be measured by comparing the weight of the polyamide composite material with the weight of the carbon nanotube-polyamide composite material after polishing.

agitator

In one embodiment, the present invention provides a stirrer for preparing the raw material mixture in the solid state.

The stirrer of the present invention,

a stirring chamber including an inner chamber accommodating the raw material mixture and an outer chamber formed to surround the inner chamber and spaced apart from the inner chamber by a predetermined distance to form an inner space;

a shaft disposed inside the inner chamber;

a driving unit providing a driving force to the shaft;

a first impeller coupled to the shaft to rotate together, disposed adjacent to a bottom surface of the inner chamber, and inclined toward a rotational direction of the shaft; and

A second impeller coupled to the shaft to rotate together, disposed above the first impeller, and inclined toward the rotational direction of the shaft may be included.

In one specific example, the agitator may further include a chamber cover for sealing the stirring chamber.

In one specific example, the stirring chamber cover,

a cover hole for circulating the inner chamber and the outer space;

a filter for shielding the cover hole; and

It may include a sealing cap sealing the cover hole.

In one specific example, the agitator may further include a circulation pump for circulating cold water or hot water in the inner space of the stirring chamber.

In one specific example, the stirrer may further include a spacer inserted into the shaft and disposed between the first impeller and a bottom surface of the inner chamber.

In one specific example, the stirrer may include a sweeper coupled to the end of the second impeller, positioned between the second impeller and the inner circumferential surface of the inner chamber, and sweeping the inner circumferential surface of the inner chamber.

One feature of the manufacturing method of the present invention is that a solid-state raw material mixture is first prepared by mixing and dispersing a solid-state monomer and a solid-state carbon nanotube at a predetermined time and speed. This feature of the present invention can significantly improve the problem that carbon nanotubes are not easily dispersed in the conventional molten monomer or polymer in a molten form.

The polymer composite material of the present invention has very good mechanical strength, particularly excellent abrasion resistance, and at the same time has electrical conductivity at a level usable as a material for equipment in the electronics industry.

The stirrer of the present invention has a specialized structure that can very effectively disperse solid-state monomers and carbon nanotubes.

1 is a diagram schematically showing the configuration of a stirrer according to an embodiment of the present invention.
2 is a view schematically showing the configuration of a stirring chamber according to an embodiment of the present invention.
3 is a perspective view of an impeller according to an embodiment of the present invention.
4 is a front view of an impeller according to an embodiment of the present invention.
5 is a plan view of an impeller according to an embodiment of the present invention.
6 is a view schematically showing the configuration of a stirring chamber according to another embodiment of the present invention.
7 is a perspective view of an impeller according to another embodiment of the present invention.
8 is a front view of an impeller according to another embodiment of the present invention.
9 is a plan view of an impeller according to another embodiment of the present invention.
10 is a photograph taken using SEM at an observation magnification of 50,000 of the polymer composite material prepared in Example 3;
11 is a photograph taken using SEM at an observation magnification of 50,000 of the polymer composite material prepared in Example 8. FIG.
12 is a photograph taken using SEM at an observation magnification of 50,000 of the polymer composite material prepared in Comparative Example 1. FIG.
13 is a photograph taken using SEM at an observation magnification of 50,000 of the polymer composite material prepared in Comparative Example 2;

Hereinafter, the structure and effect of the stirrer of the present invention will be described in more detail with reference to the drawings according to specific embodiments of the present invention. However, it should be understood that the examples and terms used therein are not intended to limit the technology described in the present specification to specific embodiments, and include various modifications, equivalents, and/or substitutions of the embodiments. In relation to the description of the drawings, similar reference numerals may be used for similar components, and overlapping description thereof will be omitted. The accompanying drawings are provided for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the present specification is not limited by the accompanying drawings.

The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves. Also, the singular expression may include the plural expression unless the context clearly dictates otherwise.

In this specification, expressions such as “A or B” or “at least one of A and/or B” may include all possible combinations of items listed together. Expressions such as "first," "second," "first," or "second," can modify the corresponding elements, regardless of order or importance, and to distinguish one element from another element. It is used only and does not limit the corresponding components. When an (eg, first) component is referred to as being “connected (functionally or communicatively)” or “connected” to another (eg, second) component, that component is It may be directly connected to the component or may be connected through another component (eg, a third component).

As used herein, "configured to (or configured to)" according to the context, for example, hardware or software "suitable for," "having the ability to," "modified to ," "made to," "capable of," or "designed to" may be used interchangeably. In some circumstances, the expression “a device configured to” may mean that the device is “capable of” with other devices or parts.

In this specification, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In this specification, particularly in the description below, the agitated object means an object that is accommodated in a stirrer and stirred, but according to the main idea of the present invention, the object of stirring is for implementing the polymer composite material of the present invention. The stirred material may be understood as a raw material mixture for realizing the polymer composite material of the present invention, in particular, a raw material mixture in a solid state. However, the stirrer of the present invention is not specifically used for the raw material mixture, and those skilled in the art will be able to apply it to agitation of various materials based on its structure.

1 is a diagram schematically showing the configuration of a stirrer 100 according to an embodiment of the present invention, and FIG. 2 is a diagram schematically showing the configuration of a stirring chamber 110 according to an embodiment of the present invention .

The stirrer 100 according to an embodiment of the present invention may include a stirring chamber 110 , a shaft 120 , a driving unit 130 , a first impeller 151 , and a second impeller 153 .

The stirring chamber 110 according to an embodiment may include an inner chamber 111 and an outer chamber 113 . The inner chamber 111 according to an embodiment may have a cylindrical shape with an open top and a flat bottom. Agitated material may be introduced into the inner chamber 111 through the open upper surface. A shaft 120 , a first impeller 151 , and a second impeller 153 , which will be described later, may be disposed in the inner chamber 111 , and the agitated material is supplied by the first impeller 151 and the second impeller 153 . It can be crushed and dispersed.

The outer chamber 113 according to an exemplary embodiment may have a cylindrical shape with an open upper surface like the inner chamber 111 , and may be formed in a shape surrounding the inner chamber 111 and spaced apart from the inner chamber 111 by a predetermined distance. An inner space may be formed as much as the inner chamber 111 and the outer chamber 113 are spaced apart from each other. In describing the stirring chamber 110 according to one embodiment, a cylindrical shape has been described as an example, but the present invention is not limited thereto, and a shape capable of accommodating the agitated material therein and accommodating the shaft 120 and the impeller 150 . This can be used in a variety of ways.

The stirring chamber 110 according to an embodiment may have an open upper surface thereof by the chamber cover 160 may be sealed. By sealing the stirring chamber 110 with the chamber cover 160, it is possible to prevent the agitated material in powder form from being scattered and leaking to the outside during the grinding and dispersing process. The chamber cover 160 according to an embodiment may further include a cover hole 161 , a filter 163 , and a sealing cap 165 . Stirred materials may be introduced into the stirring chamber 110 through the cover holes 161 formed in the chamber cover 160 , and the agitated materials scattered during the input process may be minimized. The cover hole 161 may be shielded by the filter 163 , and the cover hole 161 may be completely sealed through the sealing cap 165 . In the stirring chamber 110 , the cover hole 161 may be opened by opening the sealing cap 165 to control the internal pressure in the stirring chamber 110 , so that the agitated material scattered in this process does not leak to the outside. It can be filtered out by the filter 163 .

The agitator 100 according to an embodiment of the present invention may further include a circulation pump 140 . The circulation pump 140 may circulate hot or cold water in the inner space of the stirring chamber 110 . The circulation pump 140 may be freely changed and applied as long as it is a device capable of circulating hot or cold water. Although FIG. 1 shows that the circulation pump 140 is disposed in an arbitrary space located below the stirring chamber 110, the present invention is not limited thereto, and the position may be freely changed as needed. An inlet and an outlet for inflow of hot or cold water may be formed on the outer peripheral surface of the outer chamber 113 . The circulation pump 140 may cool or heat the internal chamber 111 by supplying hot or cold water to the internal space. Although it has been described as an example that the circulation pump 140 according to an embodiment circulates hot or cold water, it is not limited thereto and a material capable of cooling or heating the internal chamber 111 through heat exchange may be variously applied. .

The shaft 120 according to an embodiment rotates by receiving power from the driving unit 130 , and may be disposed inside the stirring chamber 110 . The shaft 120 is formed to pass through the bottom surface of the inner chamber 111 and can be rotated by a motor. The driving unit 130 may be freely applied in a form capable of providing the rotational force of the shaft 120 . Although it is illustrated in FIG. 1 that the driving unit 120 is disposed in an arbitrary space located below the stirring chamber 110, it may be freely changed as needed. The first impeller 151 and the second impeller 153 may be coupled to the shaft 120 , and the first impeller 151 and the second impeller 153 may rotate together according to the rotation of the shaft 120 . have.

3 is a perspective view of an impeller 150 according to an embodiment of the present invention, FIG. 4 is a front view of the impeller 150 according to an embodiment of the present invention, and FIG. 5 is an embodiment of the present invention It is a plan view of the impeller 150 according to.

The impeller 150 according to an embodiment of the present invention may include a first impeller 151 and a second impeller 153 . The first impeller 151 according to an exemplary embodiment may be coupled to the shaft 120 to rotate together, be disposed adjacent to the bottom surface of the inner chamber 111 and be inclined in the rotational direction. The inclination angle of the blades of the first impeller 151 may be formed to gradually increase with respect to the rotation direction. In other words, the shape of the cross-section of the blade of the first impeller 151 may be similar to that of a semi-ellipse. The first impeller 151 rotates together with the shaft 120 in a state formed to be inclined with respect to the rotational direction, thereby pressing the agitated material to the bottom surface of the inner chamber 111 . In addition, since the first impeller 151 continuously rotates together with the shaft 120 , the agitated material is pressed against the bottom surface of the inner chamber 111 and rubbed to pulverize it. When different types of agitated materials are added together, the first impeller 151 may continuously rotate and disperse the agitated materials to be mixed well while pulverizing them.

The agitator 100 according to an embodiment may further include a spacer 121 inserted into the shaft 120 and positioned between the first impeller 151 and the bottom surface of the inner chamber 111 . In order for the first impeller 151 to pulverize the agitated material well, it is necessary to maintain a uniform and fine gap with the bottom surface of the inner chamber 111 . The spacer 121 may be formed in a shape similar to a washer and be positioned between the first impeller 151 and the bottom surface of the inner chamber 111 to maintain a uniform and fine gap.

The second impeller 153 according to an embodiment may be coupled to the shaft 120 to rotate together and be disposed above the first impeller 151 . The second impeller 153 may guide the agitated substances injected into the inner chamber 111 to the bottom surface of the inner chamber 111 . The second impeller 153 may have a rectangular plate shape, and as it extends from the shaft 120 side toward the inner circumferential surface of the inner chamber 111 , it may be twisted toward the rotational direction of the second impeller 153 . For example, the wings of the second impeller 153 are coupled in the vertical direction on the shaft 120 side, but in a portion adjacent to the inner circumferential surface of the inner chamber 111 to be inclined toward the rotational direction of the second impeller 153. can Through this, the agitated material scattered in the inner chamber 111 or the agitated material adhered to the inner circumferential surface of the inner chamber 111 may be guided to the bottom surface of the inner chamber 111 .

A sweeper 155 may be disposed at an end of the second impeller 153 according to an exemplary embodiment. The sweeper 155 may be formed of a material having elasticity, and may serve to fill a gap between the second impeller 153 and the inner circumferential surface of the inner chamber 111 . Through this, the agitated material adhered to the inner circumferential surface of the inner chamber 111 may be more effectively guided to the lower surface of the inner chamber 111 . For example, the sweeper 155 may be in the form of an elastic body made of rubber or a brush.

6 is a diagram schematically showing the configuration of the stirring chamber 110 according to another embodiment of the present invention.

The stirrer 100 according to another embodiment of the present invention is similar to the stirrer 100 of FIGS. 2 to 5 , the stirring chamber 110 , the shaft 120 , the driving unit 130 , the first impeller 151 and the second 2 impellers 153 may be included. The stirring chamber 110 , the shaft 120 , the driving unit 130 , and the second impeller 153 may be substantially the same as or similar to the stirrer 100 of FIGS. 2 to 5 . However, there may be differences in the shape of the first impeller 151 as will be described later with reference to FIGS. 7 to 9 .

7 is a perspective view of an impeller 150 according to another embodiment of the present invention, FIG. 8 is a front view of the impeller 150 according to another embodiment of the present invention, and FIG. 9 is another embodiment of the present invention It is a plan view of the impeller 150 according to.

The impeller 150 according to another embodiment of the present invention may include a first impeller 151 and a second impeller 153 . The second impeller 153 according to another embodiment may be substantially the same as or similar to the second impeller 153 of FIGS. 2 to 5 . In explaining the first impeller 151 according to another embodiment, in order to help the understanding of the present invention, the difference from the first impeller 151 of FIGS. 2 to 5 will be mainly described.

The first impeller 151 according to another embodiment is coupled to the shaft 120, rotates together, is disposed adjacent to the bottom surface of the inner chamber 111, and may be formed to be inclined toward the rotational direction, and the first impeller ( The inclination angle of the blades of 151) may be formed to gradually increase with respect to the rotational direction. However, the number of blades may be increased so that the first impeller 151 can pulverize and disperse the agitated material more effectively, and a weight may be further disposed on the blades of the first impeller 151 . By pressing the wing of the first impeller 151 toward the bottom of the inner chamber 111, the weight can more effectively pulverize the agitated material, and the weight itself collides with the agitated material during the rotation of the first impeller 151 By doing so, dispersion of the agitated material can be effectively induced.

Meanwhile, in the following, the effects of the manufacturing method of the present invention and the polymer composite material prepared thereby will be demonstrated through Examples and Comparative Examples. The ingredients used in the examples below are as follows:

- Monomer: caprolactam

- carbon nanotube: multi-carbon nanotube (abbreviated as CNT), diameter: about 7 to about 20 nm (average diameter: about 12 nm); Bulk density: 80-150 kg/mㅃ; Length: about 10 to about 200 μm; Carbon purity: 94% by weight or more; Moisture content: less than 3% physical properties

- Additives for inducing polymerization: toluene diisocyanate (abbreviated as TDI) and sodium (abbreviated as Na)

<Example 1>

1,000 g of caprolactam in a solid state and 10 g of CNT in a solid state were added to a stirrer as shown in FIG. 1 . Thereafter, the mixture was stirred at room temperature at a speed of 300 to 500 rpm for 6 hours to prepare a raw material mixture in a solid state.

The raw material mixture thus prepared was transferred to a dispersing tank, and water was removed while melting in a vacuum and at about 100° C. for about 30 minutes. Then, the molten raw material mixture was divided into different containers by 1/2, and 2.5 g TDI and 0.125 g of Na were respectively added to the molten raw material mixture contained in each container, and the mixture was stirred at about 60 rpm in a vacuum and at about 100 ° C. . Then, the molten mixture contained in each vessel was combined into one, and then heated at 100°C to 120°C for 10 minutes.

Then, the molten mixture was put into a mold heated to about 160° C., polymerized for 30 minutes, and the polymer was taken out of the mold and cooled at room temperature to obtain a polymer composite material.

<Example 2>

1,000 g of caprolactam in a solid state and 10 g of CNT in a solid state were added to a stirrer as shown in FIG. 1 . Thereafter, the first stirring was carried out at room temperature at a speed of 50 to 70 rpm for 1 hour. Then, a second stirring was performed at a speed of 300 to 500 rpm for about 6 hours to prepare a raw material mixture in a solid state.

The raw material mixture thus prepared was transferred to a dispersing tank, and water was removed while melting in a vacuum and about 100° C. for about 30 minutes. Then, the molten raw material mixture was divided into different containers by 1/2, and 2.5 g TDI and 0.125 g of Na were respectively added to the molten raw material mixture contained in each container, and the mixture was stirred at about 60 rpm in a vacuum and at about 100 ° C. . Then, the molten mixture contained in each vessel was combined into one, and then heated at 100°C to 120°C for 10 minutes.

Then, the molten mixture was put into a mold heated to about 160° C., polymerized for 30 minutes, and the polymer was taken out of the mold and cooled at room temperature to obtain a polymer composite material.

<Example 3>

1,000 g of caprolactam in a solid state and 10 g of CNT in a solid state were added to a stirrer as shown in FIG. 1 . Thereafter, the first stirring was carried out at room temperature at a speed of 50 to 70 rpm for 1 hour. Then, a second stirring was carried out at a speed of 200 to 300 rpm for about 1 hour. Thereafter, a third stirring was performed at a speed of 400 to 500 rpm for about 6 hours to prepare a raw material mixture in a solid state.

The raw material mixture thus prepared was transferred to a dispersing tank, and water was removed while melting in a vacuum and at about 100° C. for about 30 minutes. Then, the molten raw material mixture was divided into different containers by 1/2, and 2.5 g TDI and 0.125 g of Na were respectively added to the molten raw material mixture contained in each container, and the mixture was stirred at about 60 rpm in a vacuum and at about 100 ° C. . Then, the molten mixture contained in each vessel was combined into one, and then heated at 100°C to 120°C for 10 minutes.

Then, the molten mixture was put into a mold heated to about 160° C., polymerized for 30 minutes, and the polymer was taken out of the mold and cooled at room temperature to obtain a polymer composite material.

<Examples 4 to 12>

As shown in Table 1, a polymer composite material was prepared in the same manner as in Example 3, except that the manufacturing conditions of the raw material mixture in the solid state were changed.

<Comparative Example 1>

1,000 g of caprolactam in a solid state was melted in a dispersion tank at about 70° C., and water was removed while melting in a vacuum and at about 100° C. for about 30 minutes. After 10 g of CNT was added to the molten caprolactam, the mixture was stirred at room temperature at a speed of 300 to 500 rpm for 6 hours to prepare a raw material mixture in a molten state.

Then, the molten raw material mixture was divided into different containers by 1/2, and 2.5 g TDI and 0.125 g of Na were respectively added to the molten raw material mixture contained in each container, and the mixture was stirred at about 60 rpm in a vacuum and at about 100 ° C. . Then, the molten mixture contained in each vessel was combined into one, and then heated at 100°C to 120°C for 10 minutes.

Thereafter, the molten raw material mixture was put into a mold heated to about 160° C., polymerized for 30 minutes, and then removed from the mold and cooled at room temperature to prepare a polymer composite material.

<Comparative Example 2>

1,000 g of caprolactam in a solid state was melted in a dispersion tank at about 70° C., and water was removed while melting in a vacuum and at about 100° C. for about 30 minutes. After 10 g of CNT is added to the molten caprolactam, the first stirring is performed at room temperature at a speed of 50 to 70 rpm for 1 hour, and then, after a second stirring at a speed of 200 to 300 rpm for about 2 hours, 400 to A third stirring was performed at a speed of 500 rpm for about 6 hours to prepare a molten raw material mixture.

Then, the molten raw material mixture was divided into different containers by 1/2, and 2.5 g TDI and 0.125 g of Na were respectively added to the molten raw material mixture contained in each container, and the mixture was stirred at about 60 rpm in a vacuum and at about 100 ° C. . Then, the molten mixture contained in each vessel was combined into one, and then heated at 100°C to 120°C for 10 minutes.

Thereafter, the molten raw material mixture was put into a mold heated to about 160° C., polymerized for 30 minutes, and then removed from the mold and cooled at room temperature to prepare a polymer composite material.

<Experimental Example 1: Physical property evaluation>

The physical properties of the polymer composite materials prepared in Examples 1 to 12 and Comparative Examples 1 to 2 were measured by the following test method, and the results are shown in Table 2.

- Tensile strength: measured by ASTM D638

- Elongation: Measured by ASTM D638

- Flexural strength: measured by ASTM D790

- Flexural modulus: measured by ASTM D790

- Impact strength: measured by ASTM D256

- Heat Deflection Temperature: Measured by ASTM D648

- Volume resistivity: measured by ASTM D257

- Abrasion rate: Using a grinding stone from CALIBRADE H-18 of TABER INDUSTRIES, USA, abrasion specimen (80x80x50mm) was polished 2,000 times with a load of 1 kg and 70 rpm to determine the weight of the polymer composite material before polishing and the weight of the polymer composite material after polishing Compare the wear rate

Item Seal
burglar
(Kg/cm ² ) elongation
( % ) curve
burglar
( Kg/cm ² ) curve
modulus of elasticity
( Kg/cm ² ) Shock
burglar
(Kg · cm / cm) heat deflection temperature
( ℃
(18.6Kg/cm ² ) ) wear rate*
( % by weight) volume specific
resistance
(Ω cm) Example 1 900 20 1,200 35,000 3.5 185 0.035 7×10E5 Example 2 920 23 1,250 36,000 4.0 187 0.023 5×10E5 Example 3 980 30 1,350 37,500 4.5 195 0.015 5×10E4 Example 4 950 27 1,300 37,500 4.3 190 0.020 2×10E5 Example 5 900 20 1,230 35,500 3.7 180 0.030 3×10E6 Example 6 950 25 1,250 35,500 4.0 185 0.025 8×10E5 Example 7 1,050 30 1,450 40,500 5.5 205 0.010 3×10E3 Example 8 880 20 1,150 35,000 3.3 180 0.032 5×10E6 Example 9 850 23 1,100 33,500 3.0 180 0.038 2×10E7 Example 10 905 20 1,205 35,000 3.8 183 0.035 3×10E6 Example 11 830 18 1,080 32,000 2.8 178 0.040 5×10E8 Example 12 810 15 1,020 31,500 2.6 175 0.045 2×10E9 Comparative Example 1 650 10 850 26,500 1.5 155 0.152 >10E11
(10E12) Comparative Example 2 680 12 900 28,000 1.8 160 0.132 >10E11
(5×10E12)

Referring to Table 2, it can be seen that Examples 1 to 12 exhibit superior effects compared to Comparative Examples 1 and 2.

All of the examples are superior to the comparative examples in all measured properties such as tensile strength, elongation, flexural strength, flexural modulus, impact strength, thermal deformation temperature, wear rate, and volume resistivity. This is considered to be because the CNTs were well dispersed by performing the manufacturing method according to the present invention. Incidentally, the examples in which the raw material mixture was dispersed and mixed by dividing it into multiple stages with different stirring speeds obtained relatively better wear rate results.

In particular, it is worth noting that the wear rate of the example is improved by at least about 3 times and at least about 10 times compared to the comparative example. This can dramatically improve the lifespan of the MC nylon of the present invention when manufacturing parts, tools, devices, equipment, etc. from the material, and furthermore, it is possible to improve the operation rate of the process using them.

In addition, the Example exhibited an intrinsic volume resistance significantly superior to that of the Comparative Example, and these results suggest that the present invention clearly solves what the conventional MC nylon failed to achieve.

10 and 11 show pictures taken using SEM of the polymer composite material prepared in Example 3 (FIG. 10) and Example 8 (FIG. 11). Referring to these drawings, it can be visually confirmed that CNTs (grey-white objects) are uniformly distributed throughout the polymerized polymer.

That is, it can be seen that the state of CNTs uniformly dispersed in the raw material mixture in the solid state is maintained even in the polymer after polymerization.

On the other hand, in particular, Comparative Examples 1 and 2 in which CNTs were dispersed in molten caprolactam, unlike Examples, had relatively poor physical properties. This is considered to be because the dispersion of CNTs in the molten monomer was not performed well.

In this regard, FIGS. 12 and 13 show photographs taken using SEM of the polymer composite material prepared in Comparative Example 1 and Comparative Example 2, respectively. Referring to the photograph, it can be seen that, unlike the previous embodiment, no gray-white object, which is CNT, was observed on the photograph.

From the results of these comparative examples, it can be understood that mixing and dispersing a solid monomer and CNT as in the present invention to prepare a raw material mixture and using the same plays a major role in preparing a polymer composite material having excellent physical properties.

Although described above with reference to the embodiments of the present invention, those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above content.

100: agitator 110: stirring chamber
111: inner chamber 113: outer chamber
120: shaft 121: spacer
130: driving unit 140: circulation pump
150: impeller 151: first impeller
153: second impeller 155: sweeper
160: chamber cover 161: cover hole
163: filter 165: sealing cap

Claims (21)

A method for producing a polymer composite material in which carbon nanotubes are dispersed in a polymer,
Preparing a solid-state monomer and solid-state carbon nanotubes;
preparing a raw material mixture in a solid state by mixing and dispersing the monomer and carbon nanotubes; and
polymerizing the raw material mixture,
In the step of preparing the raw material mixture in the solid state, the monomer in the solid state and the carbon nanotubes in the solid state are added to a stirrer to mix and disperse,
The mixing and dispersing is
A first stirring performed in the stirrer at room temperature at 50 to 70 rpm for more than 30 minutes to 1 hour;
a second stirring performed for 1 hour to 2 hours at 200 to 300 rpm in the stirrer at room temperature; and
In the stirrer at room temperature, comprising a third stirring performed at 400 to 500 rpm for 4 hours or more,
The stirrer,
a stirring chamber including an inner chamber accommodating the raw material mixture and an outer chamber formed to surround the inner chamber and spaced apart from the inner chamber by a predetermined distance to form an inner space;
a shaft disposed inside the inner chamber;
a driving unit providing a driving force to the shaft;
a first impeller coupled to the shaft to rotate together, disposed adjacent to a bottom surface of the inner chamber, and inclined toward a rotational direction of the shaft; and
A method of manufacturing a polymer composite material comprising a second impeller coupled to the shaft and rotating together, disposed above the first impeller, and inclined toward the rotational direction of the shaft. According to claim 1,
The monomer is in a solid state at room temperature, and comprises an amide functional group in the molecular structure. 3. The method of claim 2,
The monomer is caprolactam. delete delete delete According to claim 1,
Before polymerizing the raw material mixture, the method further comprising heating and melting the raw material mixture in a solid state. 8. The method of claim 7,
A method of heating the raw material mixture in a solid state to 70° C. to 110° C. under vacuum to melt it by heating for 10 to 60 minutes, and removing moisture in the raw material mixture. 8. The method of claim 7,
The method further comprising the step of dividing the molten raw material mixture by distributing it in n different containers and stirring each, then combining them again and stirring again. 10. The method according to claim 7 or 9,
Further comprising the step of adding and mixing an additive for inducing polymerization to the molten raw material mixture,
A method of adding the polymerization-inducing additive and mixing at 90° C. to 110° C. at 40 to 80 rpm for 10 to 60 minutes. 11. The method of claim 10,
The polymerization inducing additive comprises 0.4 to 0.6 parts by weight of a diisocyanate-based polymerization initiator based on 100 parts by weight of the monomer and 0.2 to 0.3 parts by weight of a basic catalyst based on 100 parts by weight of the monomer. According to claim 1,
The polymerization is to put the raw material mixture molten in a mold heated to a temperature of 160 ℃ to 170 ℃ and to polymerize for 30 to 60 minutes, the manufacturing method. According to claim 1,
The raw material mixture comprises 0.1 parts by weight to 2.5 parts by weight of carbon nanotubes based on 100 parts by weight of the monomer. delete According to claim 1,
The polymer composite material is a carbon nanotube-containing monomer cast nylon manufacturing method. According to claim 1,
The polymer composite material satisfies all of the following physical properties, a manufacturing method:
- tensile strength of 800 kg/cm ^{2 or more;}
- more than 20% elongation;
- flexural strength of 1,100 kg/cm ^{2 or more;}
- a flexural modulus of at least 30,000 kg/cm ^{2 ;}
- Impact strength of 4.0 kgf.cm/cm or more;
- Thermal deformation temperature above 175℃
- ^{Volume resistivity of 10e 3} Ω·cm or more;
- wear rate of 0.07% by weight or less. delete According to claim 1,
The agitator further comprises a chamber cover for sealing the stirring chamber,
The stirring chamber cover,
a cover hole for circulating the inner chamber and the outer space;
a filter for shielding the cover hole; and
A manufacturing method comprising a sealing cap sealing the cover hole. 19. The method of claim 18,
The agitator further comprises a circulation pump for circulating cold or hot water in the inner space of the stirring chamber. According to claim 1,
The agitator is inserted into the shaft, the manufacturing method further comprising a spacer disposed between the first impeller and the bottom surface of the inner chamber. 21. The method of claim 20,
The stirrer is coupled to the end of the second impeller, is positioned between the second impeller and the inner circumferential surface of the inner chamber, and includes a sweeper sweeping the inner circumferential surface of the inner chamber.

Images