KR20200011052A - Method of Manufacturing Carbonnanotube Pellet and Carbonnanotube Pellet Manufactured there by - Google Patents

Abstract

Provided by the present invention is a carbon nanotube pellet manufacturing method including: a step (a) of producing a mixture of polymerizable thermoplastic resin and carbon nanotubes which generate PA6 (nylon 6) in a case of reaction polymerization; a step (b) of producing a masterbatch by in-situ polymerization after adding a catalyst and an activator to the mixture of the step (a); and a step (c) of producing carbon nanotube pellets by introducing polymer resin and the masterbatch of the step (b) to an extruder having a dispersing structure for dispersion of carbon nanotubes on a screw. The carbon nanotube pellet manufactured by the method of the present invention minimizes mass production cost of products by minimizing the content of carbon nanotubes and provides advantages of excellent electrical conductivity and electromagnetic shielding efficiency by exhibiting the minimum level of electrical resistance.

Description

Method of manufacturing carbon nanotube pellets and carbon nanotube pellets produced by the same method {Method of Manufacturing Carbonnanotube Pellet and Carbonnanotube Pellet Manufactured there by}

The present invention relates to a method for producing carbon nanotube pellets and to carbon nanotube pellets prepared by the method, and more particularly, to preparing a mixture of a polymerizable thermoplastic resin and carbon nanotubes, a catalyst and activation in the mixture. Method of preparing a carbon nanotube pellet comprising the step of preparing a master batch by adding an agent and then in-situ polymerization and preparing the carbon nanotube pellet by injecting the master batch and a polymer resin into an extruder; It relates to carbon nanotube pellets produced by the production method.

Since carbon nanotubes were first discovered by Ijima, research on polymer resin composite materials using their excellent physical properties has been conducted. Regarding the development of the composite material, various composite materials that well express the physical properties of the carbon nanotubes have been developed and reported at the laboratory level, but are not meeting the expected level in mass production and distribution.

Graphene not only has a large surface area compared to other carbon materials, but also has excellent mechanical strength, thermal and electrical properties, and flexibility and transparency. Due to the excellent mechanical, electrical and thermal properties of the graphene, the graphene-filled polymer composite material may have greatly improved physical properties. In addition, graphene also exhibits excellent gas barrier properties due to its structural specificity, and thus, the polymer composite material including graphene includes various electronic devices, energy storage media, organic solar cells, heat radiation materials, film packaging materials, and biomimetic applications. It is attracting attention in the field.

On the other hand, after the rapid growth of smart devices, the need for conductive compound materials is expected to increase according to various trends such as the evolution of the Internet of Things (IoT) based on communication and the increasing proportion of automotive electronic systems. . The conductive polymer composite material prepared by incorporating the conductive filler into the polymer may have various applications depending on the surface resistance and the electrical conductivity level.

In such a market situation, nano materials such as carbon nanotubes and graphene are rapidly entering the market by replacing existing conductive polymer composite materials due to superior mechanical properties, electrical conductivity and thermal conductivity, compared to conventional conductive fillers. There is a constant demand for the development of conductive compound technology that enables low-cost processing by injection molding.

Recently, antistatic compounds incorporating commercially available multi-walled carbon nanotubes on a scale of several hundred tons to 3-5 wt% have been commercialized, but low cost is required for various applications.

Electromagnetic shielding compounds require lower levels of electrical resistance than antistatic compounds and inevitably require more than 8-10 wt% of carbon nanotubes to be incorporated into typical melt compounding processes. Failed to form.

Carbon nanotubes are the most popular conductive fillers on the market because they can improve the electrical conductivity of composite materials in small amounts due to their long aspect ratios, and multi-walled carbon nanotubes, which are relatively inexpensive, have been considered.

Since the unit cost of conductive compounds containing multi-walled carbon nanotubes is mostly due to the price of multi-walled carbon nanotubes used as conductive fillers, it is essential to reduce the amount of carbon nanotubes mixed by developing a high dispersion process to achieve low cost. Technology.

However, when a solvent is used for high dispersion of multi-walled carbon nanotubes, a long drying time is required, which leads to an increase in the cost of the compound. In addition, the non-solvent process may be implemented by using a resin having a low melt viscosity, but there is a problem that may lower the final physical properties of the compound.

In order to solve the above problems, KR Patent Application No. 10-2014-0043519 (name of the invention: a composite material of a filler and a polymer resin and a manufacturing method thereof) is a thermoplastic resin by dispersing and mixing a polymerization catalyst in a polymerizable thermoplastic resin. Preparing a composition; Preparing a masterbatch made of a filler and a polymer resin by mixing and heating the filler and the thermoplastic resin composition to in situ polymerization; And it discloses a filler and a polymer resin composite material manufacturing method comprising the step of pelletizing the addition of the polymer resin to the master batch or the master batch through a compounding process.

However, in the above-mentioned patent document, since the dispersibility of a filler is inferior, there exists a problem that the amount of filler mixing is high.

Throughout this specification, many papers and patent documents are referenced and their citations are indicated. The disclosures of cited papers and patent documents are incorporated herein by reference in their entirety, and the level of the technical field to which the present invention belongs and the contents of the present invention are more clearly described.

The inventors of the present invention minimized the content of the carbon nanotubes, but because of the minimum level of electrical resistance, and tried hard to develop carbon nanotube pellets for injection or extrusion molding excellent in electrical conductivity and electromagnetic shielding efficiency. As a result, after mixing a catalyst and an activator to a mixture of anionic polymerization type PA6 and carbon nanotubes to prepare a master batch through a polymerization reaction, the extrusion process for pellet production by mixing the master batch and a polymer resin The present invention was completed by discovering that the extruder used in the extrusion process can solve the problem described above when the dispersion structure for dispersing carbon nanotubes is included.

Accordingly, an object of the present invention is to provide a method for producing carbon nanotube pellets.

In addition, another object of the present invention to provide a carbon nanotube pellet prepared by the above production method.

In addition, another object of the present invention is to provide an antistatic tray manufactured using carbon nanotube pellets.

In addition, another object of the present invention to provide a cell phone case for electromagnetic shielding manufactured using carbon nanotube pellets.

Other objects and advantages of the present invention will become apparent from the following detailed description, claims and drawings.

The present invention provides a method for producing pellets.

The inventors of the present invention minimized the content of the carbon nanotubes, but because of the minimum level of electrical resistance, and tried hard to develop carbon nanotube pellets for injection or extrusion molding excellent in electrical conductivity and electromagnetic shielding efficiency. As a result, after mixing a catalyst and an activator to a mixture of anionic polymerization type PA6 and carbon nanotubes to prepare a master batch through a polymerization reaction, the extrusion process for pellet production by mixing the master batch and a polymer resin In the extruder used in the extrusion process, it was confirmed that the problem described above could be solved by including a dispersion structure for dispersing carbon nanotubes.

According to one aspect of the present invention, the present invention provides a method for producing carbon nanotube pellets comprising the following steps: (a) a polymerizable thermoplastic resin and a carbon nanotube which produces PA6 (nylon 6) when reacting polymerization; Preparing a mixture of; (b) adding a catalyst and an activator to the mixture of step (a) and then in-situ polymerizing to prepare a masterbatch; And (c) preparing carbon nanotube pellets by injecting the masterbatch of the step (b) and a polymer resin into an extruder equipped with a dispersion structure for dispersing carbon nanotubes in a screw.

As used herein, the term 'polymerizable thermoplastic resin that produces PA6 (nylon 6) when reacting polymerization' refers to a thermoplastic resin that is lowered in viscosity when heated and melted and polymerized to become PA6 (nylon 6) resin when heated continuously. can do.

The term 'in-situ polymerization' used in the present specification may mean that the polymerizable thermoplastic resin is melted and polymerized by heating to form a polymer resin.

As used herein, the term “master batch” may refer to a composite material before a pelletization process is performed as a composite material obtained by a mixture of a filler and a thermoplastic resin composition through a polymerization process.

As used herein, the term “dispersion structure” may refer to a structure capable of inducing a state of division, phase change, or mixing of the injected material due to the shape peculiar to the structure.

As used herein, the term 'pellet' may refer to a powder or granulated state after mixing and extruding a material including a filler and a polymer resin in a molten state and then grinding or cutting.

As used herein, the term 'carbon nanotube' may mean any carbon-based material capable of bonding at the molecular level while being nano units (1000 nm or less) in size.

In the present invention, it is very important to use a polymerizable thermoplastic resin that produces PA6 (nylon 6) when reacting polymerization. This is because caprolactam, a polymerizable thermoplastic resin that produces PA6 (nylon 6) when it is reactively polymerized, is inexpensive compared to other polymerizable thermoplastic resins, and the mechanical properties of the finished product using the reactively polymerized PA6 are very high. Because it is excellent.

In the present invention, it is very important to prepare a master batch through the in-situ polymerization process. Because, when manufacturing the master batch through the in-situ polymerization process, it is possible to remarkably improve the dispersion of high concentration carbon nanotubes inside the master batch to significantly increase the surface resistance and electromagnetic shielding efficiency of the carbon nanotube pellets. Because.

According to a preferred embodiment of the present invention, the polymerizable thermoplastic resin of step (a) of the present invention may preferably be in powder form.

According to a preferred embodiment of the present invention, the catalyst of step (b) of the present invention may preferably be a sodium metal.

According to a preferred embodiment of the present invention, the activator of step (b) of the present invention may preferably be diisocyanate.

In the present invention, it is very important to add sodium metal as a catalyst and diisocyanate as an activator. This is because the addition of diisocyanate as a catalyst and sodium metal as a catalyst to a polymerizable thermoplastic resin and a carbon nanotube mixture that produces PA6 (nylon 6) upon reaction polymerization does not include a catalyst and an activator. This is because the in situ polymerization time can be significantly reduced compared to the case.

According to a preferred aspect of the present invention, the masterbatch of the present invention preferably is based on 100 parts by weight of the polymerizable thermoplastic resin, 0.05 to 0.1 parts by weight of the sodium metal and 100 parts by weight of the polymerizable thermoplastic resin Diisocyanate may comprise 0.1-2.0 parts by weight.

According to a preferred embodiment of the present invention, the carbon nanotube pellet of the present invention may preferably comprise 0.1-3% by weight of the carbon nanotubes based on the weight of the carbon nanotube pellets.

In the present invention, containing 0.1-3% by weight of the carbon nanotubes is a very important configuration. Because, when manufacturing carbon nanotube pellets by the general method, the carbon nanotube pellets should contain 5-20% by weight of carbon nanotube pellets to exhibit the desired surface resistance and electromagnetic shielding efficiency. In this case, even when the carbon nanotubes contain 0.1-3% by weight, the surface resistance and electromagnetic shielding efficiency are equivalent to those of the carbon nanotube pellets containing 5-10% by weight of carbon nanotubes, thereby producing carbon nanotube pellets. This can be lowered significantly.

According to a preferred embodiment of the present invention, the polymerization temperature in the in-situ polymerization of the present invention may be preferably 130-260 degrees Celsius.

According to a preferred embodiment of the present invention, the polymer resin of the present invention may preferably be a PA6 (nylon 6) resin or a resin miscible with the PA6 resin.

According to a preferred aspect of the present invention, the extruder of the present invention is preferably a barrel, a hopper installed on one side of the barrel to inject the raw material into the barrel, the raw material installed in the barrel and introduced into the barrel A screw for conveying in one direction, a dispersing structure for dispersing the molten raw material conveyed by the screw, the heating unit for heating the raw material introduced into the barrel and the other end of the barrel is melted And a discharge port provided with a mold for discharging the raw material and forming the molten raw material into a specific shape.

According to a preferred aspect of the present invention, the dispersion structure of the present invention is preferably formed in plurality in the middle portion of the screw, the shape of the dispersion structure is repeated mixing and separation of the molten raw material in the barrel It may be a shape that can be flown while.

In the present invention, manufacturing carbon nanotube pellets using an extruder equipped with a dispersion structure for dispersing carbon nanotubes on a screw is a very important configuration. When manufacturing carbon nanotube pellets using an extruder equipped with a dispersing structure for dispersing carbon nanotubes on a screw, the carbon nanotube pellets are significantly improved by significantly improving the dispersion of high concentrations of carbon nanotubes inside the carbon nanotube pellets. This is because the surface resistance and the electromagnetic wave shielding efficiency of can be significantly increased.

That is, the in-situ polymerization process can significantly improve the dispersion degree of the carbon nanotubes included in the masterbatch, and through the extruder equipped with a dispersion structure for dispersing the carbon nanotubes in the screw The degree of dispersion of the carbon nanotubes (exactly the degree of dispersion of the masterbatch) contained in the nanotube pellets can be significantly improved.

According to another aspect of the invention, the present invention comprises the steps of (a) preparing a mixture of polymerizable thermoplastic resin and carbon nanotubes to produce PA6 (nylon 6) when the reaction polymerization; (b) adding a catalyst and an activator to the mixture of step (a) and then in-situ polymerizing to prepare a masterbatch; And (c) preparing carbon nanotube pellets by inserting the masterbatch and polymer resin of step (b) into an extruder equipped with a dispersion structure for dispersing carbon nanotubes in a screw. Including a tube pellet, the carbon nanocube pellets comprises the carbon nanotubes 0.1-1% by weight based on the weight of the carbon nanotube pellet, the surface resistance of the carbon nanotube pellets is 100-10000 Ω / sq, The electrical conductivity of carbon nanotube pellets provides an antistatic tray manufactured using carbon nanotube pellets having a 0.00001-0.01 S / m.

In the present invention, the matters related to the manufacturing method of the carbon nanotube pellets are overlapped with the above-described method for producing the carbon nanotube pellets, and thus, detailed descriptions thereof will be omitted in order to prevent the present specification from being excessively complicated.

According to another aspect of the invention, the present invention comprises the steps of (a) preparing a mixture of a polymerizable thermoplastic resin and carbon nanotubes to produce PA6 (nylon 6) when the reaction polymerization; (b) adding a catalyst and an activator to the mixture of step (a) and then in-situ polymerizing to prepare a masterbatch; And (c) preparing carbon nanotube pellets by inserting the masterbatch and polymer resin of step (b) into an extruder equipped with a dispersion structure for dispersing carbon nanotubes in a screw. Including a tube pellet, the carbon nanocube pellets include the carbon nanotubes 2.0-3.0 wt% based on the weight of the carbon nanotube pellet, the surface resistance of the carbon nanotube pellet is 10-100 Ω / sq, The electrical conductivity of carbon nanotube pellets provides an electromagnetic shielding cell phone case manufactured using carbon nanotube pellets of 10-1000 S / m.

In the present invention, the matters related to the manufacturing method of the carbon nanotube pellets are overlapped with the above-described method for producing the carbon nanotube pellets, and thus, detailed descriptions thereof will be omitted in order to prevent the present specification from being excessively complicated.

According to another aspect of the present invention, in the carbon nanocube pellets prepared by reacting carbon nanotubes and thermoplastic resins, the carbon nanotube pellets are polymerizable to produce PA6 (nylon 6) when the reaction polymerization is carried out. The carbon nanocube pellets are prepared by reacting a thermoplastic resin and a carbon nanotube powder. The carbon nanocube pellets contain 0.1-3.0 wt% of the carbon nanotubes based on the weight of the carbon nanotube pellets, and the surface resistance of the carbon nanotube pellets is 10-. 10000 Ω / sq, and the carbon nanotube pellets have an electrical conductivity of 0.00001-1000 S / m.

According to a preferred embodiment of the present invention, the carbon nanotube pellet of the present invention preferably comprises the steps of (a) preparing a mixture of a polymerizable thermoplastic resin and a carbon nanotube which produces PA6 (nylon 6) upon reaction polymerization; (b) adding a catalyst and an activator to the mixture of step (a) and then in-situ polymerizing to prepare a masterbatch; And (c) preparing a carbon nanotube pellet by injecting the masterbatch of the step (b) and a polymer resin into an extruder equipped with a dispersing structure for dispersing carbon nanotubes in a screw. .

In the present invention, the matters related to the manufacturing method of the carbon nanotube pellets are overlapped with the above-described method for producing the carbon nanotube pellets, and thus, detailed descriptions thereof will be omitted in order to prevent the present specification from being excessively complicated.

The features and advantages of the present invention are summarized as follows:

(1) The present invention provides a method for preparing carbon nanotube pellets comprising the following steps: (a) preparing a mixture of a polymerizable thermoplastic resin and carbon nanotubes that produces PA6 (nylon 6) upon reaction polymerization; step; (b) adding a catalyst and an activator to the mixture of step (a) and then in-situ polymerizing to prepare a masterbatch; And (c) preparing carbon nanotube pellets by injecting the masterbatch of the step (b) and a polymer resin into an extruder equipped with a dispersion structure for dispersing carbon nanotubes in a screw.

(2) The carbon nanotube pellets prepared by the method of the present invention can minimize the mass production cost of the product by minimizing the content of carbon nanotubes, as well as exhibit a minimum level of electrical resistance, so that electrical conductivity and electromagnetic shielding efficiency This offers remarkably superior advantages.

1 shows the electrical conductivity and the shielding rate of the carbon nanotube pellets according to the carbon nanotube content.
Figure 2 shows the formation reaction of the imide dimer during the anionic polymerization of PA6.
Figure 3 shows a flow chart of the carbon nanotube pellet manufacturing method according to an embodiment of the present invention.
Figure 4 shows the difference in the reaction time of the anionic polymerization type PA6 with or without a catalyst and activator.
Figure 5 shows the difference in surface resistance according to the carbon nanotube content and processing method.
Figure 6 shows the appearance of the dispersion structure for the dispersion of the screw and carbon nanotubes included in the extruder.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Although the embodiments of the present invention have been described with reference to the accompanying drawings, this will be described for the purpose of illustration, and the technical concept and construction and operation of the present invention are not limited thereto.

In the embodiments of the present invention, a filler (preferably a powder-type filler) is mixed with a composition (preferably a powder-type composition) in which a polymerization catalyst and a polymerizable thermoplastic resin are dispersed and mixed. Master batches are prepared by in-situ polymerization and are also pelletized via an extrusion process.

Accordingly, even when the composite material of the filler and the polymer resin is manufactured, in particular, in mass production, the filler content may be included in a low content of 3 wt% or less of the composite. In addition, as described above, even if the content is low, a composite material of a polymer resin having greatly improved physical properties such as mechanical properties, thermal properties, and electrical properties, in particular, electrical properties can be obtained.

In the method of preparing a filler and a polymer resin composite material according to the embodiments of the present invention, preparing a thermoplastic resin composition by dispersing and mixing a polymerization catalyst in a polymerizable thermoplastic resin, and mixing and heating a filler and the thermoplastic resin composition Preparing a master batch composed of a filler and a polymer resin by in situ polymerization, and melting the mixture of the polymer resin further added to the master batch or the master batch, mixing the mixture in a molten state, and extruding the pellets.

Hereinafter, each step will be described. Since carbon nanotubes among fillers are particularly difficult to induce high dispersion, embodiments of the present invention may be usefully applied. Hereinafter, carbon nanotubes among fillers will be described below. However, all kinds of fillers, such as other fillers such as fillers of non-carbon based materials (such as metal fillers or ceramic fillers) and non-nano size micro fillers, are highly dispersed in the polymer resin composite material. Embodiments of may be suitably used. In addition, the fillers may use one or more combinations.

3 is a view schematically showing a process for preparing a carbon nanotube and a polymer resin composite material filler according to an embodiment of the present invention.

Referring to FIG. 3, in an embodiment of the present invention, a polymerizable thermoplastic resin and carbon nanotubes are first dispersed and mixed by using a mixer to prepare a mixture.

The polymerizable thermoplastic resin is then used to have a low melt viscosity to facilitate penetration and impregnation into the nano carbon nanotubes in the master batch manufacturing step.

That is, the polymerizable thermoplastic resin has a low melt viscosity of, for example, several tens to several hundred cps, and may be, for example, a cyclic butylene terephthalate (CBT), a caprolactam, or an oligomer resin. The CBT may be polybutylene terephtalate (PBT) after polymerization, the caprolactam may be a polyamide resin (nylon 6) after polymerization, and the oligomer resin may be a polymer resin after polymerization. In particular, caprolactam resin is not only excellent in heat resistance and mechanical strength, but also inexpensive and suitable as a composite material.

Among these, anion polymerization type PA6 (nylon 6) is an optimal reactive polymerization type thermoplastic resin for applying to injection products because the unit cost is less than half as low as CBT and thermoplastic DCPD.

PA6 is an aliphatic polyamide resin with amide bonds. In 1939, DuPont Carothers first invented a synthetic fiber called PA6.6. In addition, PA6 is a German I.G. It was first used in synthetic fibers in 1942 by Schlack of Farben, and is now commercialized in various parts, and has been developed into various types such as PA 4, 11, 12 and 610.

Among them, a general polymerization method of PA6 is a condensation polymerization method and an anion polymerization method of lactam which is a cyclic monomer.

In the case of the condensation polymerization method, which is a common commercial method, the lactam is hydrolyzed and ring-opened as shown in the following figure, and then reacted at a high temperature for a certain time to produce condensation reaction between the ring-opened monomers. It is also called hydrolysis polymerization because the reaction proceeds by hydrolyzing the first monomer.

In the case of PA6 condensation polymerization, the reaction is simple, the process cost is low, and the polymerization can be easily carried out, but the reaction time is long, and the degree of polymerization cannot be increased.

In the case of anionic polymerization applied to the present invention, it begins by forming Lactamate by an anionic catalyst, and the anionic catalyst used here includes alkyl lithium, Grgnard reagent, sodium hydride, sodium metal, organo-metallic compound, etc. .

The lactamate originally disclosed in PA6 anion polymerization should proceed with the reaction of carbonyl of lactam and the formation of imide dimers while opening the ring, as shown in FIG. Due to the polymerization characteristics, lactams attacked with carbonyl by lactamate lose hydrogen by sodium, and thus anionized lactams are very unstable, making it difficult to form imide dimers.

Therefore, the reaction rate is slow and the reaction does not proceed completely. This is called the induction period. Due to this long induction period, the monomer alone is not commercially available, and an activator is a material required for commercial anionic polymerization.

The activator generally uses lactam compounds in which N-acyl, isocyanate, etc. are bound, or carboimide is used directly, and such activator is acyl substitution of lactam. The imide dimer is made externally by reaction or urethane reaction with isocyanate, and then added to the polymerization to remove the reaction mechanism (derivative group) starting from the monomer.

That is, the present invention is a technology capable of producing an excellent anionic PA6 polymer by optimizing the catalyst and the activator and optimizing the reaction conditions in the polymerization process.

The polymerizable thermoplastic resin that produces PA6 (nylon 6) in the case of reaction polymerization may be in the form of powder or pellets.However, in-situ polymerization after powder mixing in the preparation of the masterbatch described later may lead to carbon nanotubes. From the viewpoint of being preferred for dispersing, the thermoplastic resin is preferably in the form of a powder.

The catalyst is to be mixed with a polymerizable thermoplastic resin that produces PA6 (nylon 6) when the reaction polymerization to form a PA6 resin composition, which can induce and promote the polymerization reaction of the thermoplastic resin.

Alkyl lithium, Grgnard reagent, sodium hydride, sodium metal or organo-metallic compound, etc. may be used as the catalyst, in particular sodium metal.

In the reaction polymerization, a mixture of a polymerizable thermoplastic resin and a catalyst that produces PA6 (nylon 6) is mixed using a carbon nanotube and a thinky mixer.

The polymerizable thermoplastic resin of a mixture of a polymerizable thermoplastic resin and a catalyst which produces PA6 (nylon 6) when reacted and mixed with carbon nanotubes is impregnated between the carbon nanotubes with a significant drop in viscosity during melting to enable even dispersion. While polymerizing to prepare a masterbatch. Accordingly, even when the carbon nanotubes are contained in a low content of 3 wt% or less of the carbon nanotube pellets, it is possible to improve high electrical conductivity and electromagnetic shielding efficiency, thereby improving physical properties of the carbon nanotube pellets.

The method of mixing the carbon nanotubes with the mixture of the polymerizable thermoplastic resin and the catalyst which produces PA6 (nylon 6) when reacting polymerization is not particularly limited as long as the thermoplastic resin composition and the carbon nanotubes can be uniformly mixed.

In an exemplary embodiment, the mixing process may be performed using a thinky mixer or a ball mill.

After the mixing, in situ polymerization is performed. That is, a mixture of a thermoplastic resin composition and a catalyst and a mixture of carbon nanotubes are provided to a polymerizer and in situ polymerized to prepare a masterbatch made of carbon nanotubes and a polymer resin. As described above, through the in-situ polymerization process, the polymer resin is uniformly infiltrated and impregnated between the carbon nanotubes as described above, thereby producing a master batch in which the carbon nanotubes are evenly dispersed.

Polymerizable thermoplastic resins undergo rapid polymerization at high temperatures and slow polymerization at low temperatures. Therefore, it is made to heat in the range of the temperature before thermal decomposition more than the polymerization start temperature of the said thermoplastic resin. In addition, it is preferable that the polymerizable thermoplastic resin is heated to a polymerization start temperature within a short time, maintained at a polymerization start temperature to a temperature before pyrolysis, and then rapidly cooled.

For example, a polymerizable thermoplastic resin that produces PA6 (nylon 6) when reacting polymerization is melted at about 130 ° C and polymerization starts at 150 ° C or higher and proceeds faster at higher temperatures, but may be pyrolyzed when it exceeds 260 ° C. It is desirable to heat to the temperature range (eg 150 ° C. to 260 ° C.) within a short time (eg more than 0 seconds and up to 30 seconds), and to maintain a constant time (eg 1 minute to 24 hours, possible holding time is small). Then cool rapidly (e.g., 0 seconds to 60 seconds or less).

In an exemplary embodiment, the heating and cooling process for the in situ polymerization may be performed using temperature control of the mold. That is, after preparing a mixture by mixing the thermoplastic resin composition and nanocarbon, it is put into a mold, and the mold is rapidly heated to have a temperature in the range of 150 ℃ to 260 ℃ for a short time of more than 0 seconds to 30 seconds or less After that, it is maintained for 1 minute to 24 hours within the above temperature range. After the holding process, the mold may be rapidly cooled to room temperature for more than 0 seconds to 60 seconds or less. The heating rate or cooling rate may be, for example, 40 ° C to 50 ° C per second.

In an exemplary embodiment, it is desirable to heat the mold to a temperature of 250 to 260 ° C. and hold at that heating temperature for 1 to 2 minutes.

When the mold is rapidly heated as described above, and then cooled for a short time after maintaining a predetermined time, it is advantageous to mass-produce a composite material of carbon nanotubes and a polymer resin because the polymer composite material can be manufactured at high speed. In addition, since only the mold is rapidly cooled, it is possible to block factors that may affect the product properties, thereby producing a composite material having a uniform physical property.

In an exemplary embodiment, hot pressing may be performed by applying pressure in addition to heating when the master batch is manufactured. Such thermocompression may be made in a thermoforming mold.

The masterbatch prepared as described above can distribute the carbon nanotubes evenly in the masterbatch even when the content of the carbon nanotubes is low (for example, 3 wt% or less). In particular, powder carbon nanotubes and powdery mixtures (composition polymerizable thermoplastic resin and catalyst are dispersed and mixed to produce PA6 (nylon 6) when reacting polymerization) are mixed or powder mixed and then in situ polymerization It is particularly preferable to induce very even dispersion in the masterbatch even when the content of carbon nanotubes is low. As such, as the carbon nanotubes are manufactured, they contribute to the improvement of physical properties of the final carbon nanotube pellets. In particular, it can be made to have an excellent effect in terms of electrical conductivity, surface resistance and electromagnetic shielding rate.

Next, the composite material of the carbon nanotubes and the polymer resin in the masterbatch form is pelletized through an extrusion process (see FIG. 3).

In an exemplary embodiment, the pellet manufacturing step begins by incorporating the prepared masterbatch or the masterbatch with additional polymer resin in the hopper of the extrusion equipment. The polymer resin further used preferably uses a resin that is miscible with the thermoplastic resin that was used to prepare the composite material in the masterbatch form.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

Preparation Example: Preparation of Carbon Nanotube Pellets

Preparation Example 1 Preparation of Carbon Nanotube Pellets

Preparation Example 1-1 Preparation of Thermoplastic Resin Mixture

In order to prepare carbon nanotube pellets according to the present embodiment, multi-walled carbon nanotubes prepared by Hanwha Nanotech and not subjected to a special pretreatment process are prepared. Was dispersed and mixed to prepare a thermoplastic resin mixture.

Preparation Example 1-2 Preparation of Masterbatch

The carbon nanotubes and the thermoplastic resin mixture were uniformly mixed, heated to 250 ° C., and then press-molded at 20 MPa compression pressure for 2 minutes to induce a polymerization reaction (in situ polymerization) to prepare a master batch. The master batch made of the carbon nanotube and the thermoplastic resin mixture prepared by the reaction is 2mm thick.

Preparation Example 1-3 Pelletization

In the masterbatch, the content ratio of carbon nanotubes was 30 wt%, and the polymer resin was added to the masterbatch in various compositions and extruded to pelletize. Specifically, PA6 resin was mixed with the masterbatch in an extruder hopper and then extruded. The biaxial extrusion equipment used is a model including a screw equipped with a plurality of distributing structures (see FIG. 6 below), and the process conditions are as follows. The temperatures from the barrel to the nozzles were 260, 250, 250, 250, 240, 200 and 180 ° C., and the screw and mixing speeds were 300 and 24 rpm, respectively. The carbon nanotube content in the prepared carbon nanotube and polymer resin composite material was 1.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt% and 10.0 wt% (Examples 1-10).

Preparation Example 2 Preparation of Comparative Example Carbon Nanotube Pellets

PA6 resin was mixed with the carbon nanotube powder in the extruder hopper and the extrusion process was performed. The twin screw extrusion equipment used is TEK20 model of SM PLATEK of Korea and the process conditions are as follows. The temperatures from the barrel to the nozzles were 260, 250, 250, 250, 240, 200 and 180 ° C., and the screw and mixing speeds were 300 and 24 rpm, respectively. The carbon nanotube content in the final prepared carbon nanotube pellet was 1.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt % And 10.0 wt% (Comparative Examples 1 to 10).

Experimental Example

Experimental Example 1 Measurement of In Situ Polymerization Reaction Time According to the Presence of Catalyst and Activator

Preparation of carbon nanotube pellets in the same manner as in Preparation Example 1 described above, but proceeding in-situ polymerization without the addition of a catalyst and an activator to prepare a master batch, the reaction time was measured to measure the The reaction time for preparing the master beach prepared by the method was compared, and the results are shown in FIG. 4.

Experimental Example 2 Measurement of Surface Resistance of Carbon Nanotube Pellets According to Manufacturing Process

The surface resistance of the carbon nanotube pellets prepared by the method of Example 1 to Example 10 and the carbon nanotube pellets prepared by the method of Preparation Examples 1 to 10 was measured, and the results are shown in FIG. 5. Here, the surface resistance measurement environment of the carbon nanotube pellets was a place where the electromagnetic shielding is sufficiently. In addition, the measurement conditions were in principle maintained at a temperature of 25 ± 1 ° C and a relative humidity of 60% or less. After leaving the sample in the measurement environment for 30 minutes or more to reach a constant temperature, the surface resistance was measured.

Claims (10)

Carbon nanotube pellet manufacturing method comprising the following steps:
(a) preparing a mixture of polymerizable thermoplastic resin and carbon nanotubes that when reacted polymerize produces PA6 (nylon 6);
(b) adding a catalyst and an activator to the mixture of step (a) and then in-situ polymerizing to prepare a masterbatch; And
(c) preparing a carbon nanotube pellet by injecting the master batch of the step (b) and a polymer resin into an extruder equipped with a dispersion structure for dispersing carbon nanotubes in a screw.
The method of claim 1,
The polymerizable thermoplastic resin of step (a) is a carbon nanotube pellet manufacturing method, characterized in that the powder form.
The method of claim 2,
The catalyst of step (b) is a carbon nanotube pellet manufacturing method, characterized in that the sodium (Sodium) metal.
The method of claim 3, wherein
Carbon nanotube pellet manufacturing method, characterized in that the activator of step (b) is diisocyanate.
The method of claim 4, wherein
The masterbatch may include 100 parts by weight of the polymerizable thermoplastic resin, 0.05-0.1 parts by weight of the sodium metal and 0.1-2.0 parts by weight of the diisocyanate based on 100 parts by weight of the polymerizable thermoplastic resin. Carbon nanotube pellet manufacturing method.
The method of claim 5, wherein
The carbon nanotube pellet is a carbon nanotube pellet manufacturing method comprising 0.1-3% by weight of the carbon nanotube pellet based on the weight of the carbon nanotube pellet.
The method of claim 6,
In the in-situ polymerization, the polymerization temperature is carbon nanotube pellet manufacturing method, characterized in that 130 to 260 degrees Celsius.
The method of claim 7, wherein
The polymer resin is a carbon nanotube pellet manufacturing method characterized in that the resin is miscible with PA6 (nylon 6) resin or PA6 resin.
The method of claim 8,
The extruder is installed in the barrel, a hopper installed on one side of the barrel to inject the raw material into the barrel, a screw installed in the barrel to transfer the raw material introduced into the barrel in one direction, and installed in the barrel. A dispersing structure for dispersing the molten raw material conveyed by the screw, a heating unit for heating the raw material introduced into the barrel and the other end of the barrel to discharge the molten raw material, the molten raw material in a specific shape Carbon nanotube pellet manufacturing method comprising a discharge port provided with a molding die.
The method of claim 9,
The dispersion structure is formed in plurality in the middle portion of the screw, the shape of the dispersion structure is carbon nanotubes, characterized in that the molten raw material in the barrel can be flowed while mixing and separation is repeated Pellet production method.

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