KR20200074606A - Polytetra fluoroethylene-carbon nano tube composite with good electronic property - Google Patents

Abstract

The present invention relates to a method of manufacturing a polytetrafluoroethylene (PTFE)-carbon nanotube (CNT) composite material having electrical conductivity. The present invention, more specifically, relates to a method of manufacturing a PTFE-CNT composite material having electrical conductivity, wherein the PTFE-CNT composite material has been improved to have electrical conductivity capable of replacing metals by incorporating CNT among carbon-based materials with a PTFE resin having excellent chemical resistance.

Description

PTFE-CNT composite material with electrical conductivity{Polytetra fluoroethylene-carbon nano tube composite with good electronic property}

The present invention relates to a composite material of PTFE (Polytetrafluoroethylene)-CNT (Carbon Nano Tube) having electrical conductivity, and carbon nanotubes (CNT) are incorporated in a carbon-based material to a PTFE (Polytetrafluoroethylene) resin having excellent chemical resistance. The present invention relates to a PTFE-CNT composite material having improved electrical conductivity to have replaceable electrical conductivity.

There are many industrial groups dealing with hazardous compounds at industrial sites.

At this time, the harmful compound refers to a strong acid, strong alkali, and toxic substances such as hydrochloric acid, nitric acid, sulfuric acid, etc., which are found in many chemical manufacturing factories, PCBs, plating factories, etc. that make semiconductor harmful compounds.

However, in recent years, incidents of hazardous compound spills have increased rapidly, and secondary accidents due to environmental pollution, fires, etc., and property loss due to accidents have increased. This is a lack of facility management.

As the core of such facility management, a high-sensitivity sensor with excellent chemical resistance to detect fluid leakage is required.

For example, in the semiconductor industry, a device that detects a solution leakage accident in the process of washing with an acidic solution, that is, a high-sensitivity sensor is required, and excellent electrical conductivity is required for fast signal transmission.

However, the metal, which is an excellent electrical conductor, is very chemically resistant to acidic substances and cannot be used.

As such, since a metal cannot be used due to corrosion problems as a material for the sensor, and particles must not be generated in the material in a high-cleanliness management area such as a semiconductor, there is no sensor material satisfying this.

Therefore, a method capable of solving this requires a new material of the sensor suitable for this, and the new material should not have particles and should have chemical resistance that does not corrode, endure at high temperatures, and in particular, function as a high-efficiency sensor. It should be possible to replace the metal.

Conventionally, as a material that can replace metal, a composite material in which a polymer resin is mixed with a conductive filler for electrical conductivity has been developed and used in various fields.

As a conductive filler in the production of polymer resins, well-known fine metallic powders such as carbon black, graphite, silver, copper, nickel, aluminum, etc. are uniformly used. There is a way to disperse.

However, in order for these conductive fillers to impart conductivity to the polymer, it is necessary to form a pathway in which the fillers have continuity between particles in the polymer resin.

That is, the metal particles or the carbon black particles are in close contact with each other in the material so that the conductive particles must be able to connect electrons to each other.

For example, when carbon black is added to a urethane resin to impart electrical conductivity, approximately 15 to 30% by weight of carbon black is used relative to the weight of the resin, but 40% by weight or more is used to obtain better conductivity. Is required.

However, the introduction of such a large amount of carbon black makes it difficult for the particles to be uniformly dispersed, reduces the melt viscoelasticity of the resin, and causes the filler particles to aggregate with each other, resulting in an extremely high viscosity. .

As a result, the properties of the polymer resin itself are significantly lowered, and problems such as contamination due to abrasion and short circuit of electrical conductivity occur.

On the other hand, in the case of using a metal powder, the metal powder has a specific surface area smaller than that of carbon black, so that it has to be blended in an amount of 2 to 3 times or more to generate conductivity.

On the other hand, as a specific example that discloses a method for imparting conductivity to a polymer resin or an elastic body, Japanese Patent Application Laid-Open No. 9-000816, Japanese Patent Laid-Open No. 2000-077891, U.S. Patent No. 6,768,524, U.S. Patent No. 6,784,363 and U.S. Patent No. 4,548,862 And the like.

In addition, as a conductive composite material using a polymer resin and carbon nanotubes, Korean Patent Publication No. 10-2012-0077647, “Method for Manufacturing Polymer/Carbon Nanotube Composite Materials”, and Korean Patent Publication No. 10-2011-0078154 And a carbon nanotube-polymer nanocomposite material to which a fluidized layer multi-walled carbon nanotube is applied and a method of manufacturing the same.

However, the above-mentioned prior art techniques require a very high chemical resistance, such as a sensor material for detecting the leakage of harmful chemicals, while requiring sufficient electrical conductivity to sufficiently replace the metal, and requiring various characteristics. It could not be said that it is suitable as a material for high-sensitivity sensor for leaking solution in chemical process.

Therefore, there is still a need to develop a new material that can be used in certain places and environments where strong chemical resistance to chemicals, low electrical resistance, and pollution prevention, such as a clean process, are required.

Korean Patent Publication No. 10-2012-0077647 "Method for manufacturing polymer/carbon nanotube composite materials" Korean Patent Publication No. 10-2011-0078154 "Carbon nanotube-polymer nanocomposite material applied with multi-walled carbon nanotubes of fluidized layer and method for manufacturing the same"

The present invention was created in consideration of various problems in the prior art as described above, and is prepared to meet the current market conditions, and has strong chemical resistance to chemicals, low electrical resistance, and prevention of contamination such as a clean process. The main purpose is to provide a PTFE-CNT composite material having electrical conductivity that can be used in specific places and environments where is required.

In addition, another object of the present invention is to provide a PTFE-CNT composite material having electrical conductivity with an electrical resistance of 1.00E+00Ω.cm to 1.00E-02Ω.cm volume resistivity.

The present invention as a means for achieving the above object, a preparation step of heating the stirring chamber temperature 30 ~ 60 ℃;

Raw material input step of introducing NMP mixed with 10-30% by weight of PTFE powder, 1-10% by weight of CNT mixture and lithium bromide as a polar organic solvent into the stirring chamber based on 100% by weight

A first stirring step of stirring for a stirring time proportional to the total amount of raw material input while controlling the temperature and pressure of the stirring chamber within a preset range;

When the viscosity (Viscosity) inside the stirring chamber is 3,000 to 5,000 CPS, a mixture of vinylidene fluoride and perfluoro-1,3-dioxole in a weight ratio of 1:1 based on 100 parts by weight of the polar organic solvent 0.1-0.2 Parts by weight; C ₁₈ H ₂₄ N ₂ 0.2-0.3 parts by weight and C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti 0.3-0.6 parts by weight of functional control agent input step;

Secondary stirring step to stop by reacting and stirring for 30 to 60 minutes after adding the functional regulator;

An organic solvent removal step of removing the liquid organic solvent after the second stirring;

Provided PTFE-CNT composite material having electrical conductivity, characterized in that produced by a manufacturing method comprising; low-temperature drying step of manufacturing a composition obtained by removing the organic solvent in the liquid at a low temperature to synthesize CNT composite material on PTFE. do.

At this time, it is also characterized in that the product produced in the low-temperature drying step is pulverized to commercialize it as one of powder, sheet, film, or bar products.

In addition, the CNT mixture introduced in the raw material injection step is characterized by using a mixture consisting of 50% by weight of MWCNT having a particle size of 5-15nm, 40% by weight of polypropylene resin as a wrapping agent, and 10% by weight of graphite. have.

In addition, the primary and secondary agitation steps,

Mixing screw rotating step of rotating the mixing screw inserted into the stirring chamber,

It is also characterized in that the stirring chamber rotates at the same time to rotate the stirring chamber in the opposite direction to the mixing screw.

In addition, the primary and secondary stirring steps,

The mixing screw is rotated at a high speed of 5,000 to 1,5000 RPM, and the stirring chamber is also characterized by rotating at a low speed of 1 to 200 RPM.

In addition, the primary and secondary stirring steps,

It is also characterized by stirring while varying the rotation speed of the mixing screw and the stirring chamber.

In addition, the stirring chamber rotating step is characterized by repeatedly controlling on/off by an intermittent rotation method.

In addition, the polar organic solvent in the raw material injection step is characterized in that the lithium bromide and NMP (N-Methyl-2-pyrrolidone) is a solvent mixed in a weight ratio of 0.5:9.5.

According to the present invention, the following effects can be obtained.

First, a PTFE-CNT composite material having an electrical conductivity function synthesized by adding CNT as a conductive filler to a PTFE resin known to have the best chemical resistance among polymer materials can be provided.

Second, the PTFE-CNT composite material can provide a composite material having a conductive function while maintaining the characteristics of the PTFE itself, so it is possible to provide a specific place where strong chemical resistance to chemicals, low electrical resistance, and pollution prevention such as clean processes are required. There is an advantage that can be used in the environment.

Third, it is possible to realize low electrical resistance characteristics (Volume Resistivity of 1.0E+00Ω.cm~1.0E-02Ω.cm).

Fourth, it can be applied in various fields such as electricity, electronics, telecommunications, automobile, medical, aviation, etc. using PTFE-CNT composite material, and it is possible to produce high quality products.

1 is a classification comparison of the electrical resistance of the composition to impart electrical conductivity to the polymer resin.
Figure 2 is a manufacturing process diagram for explaining an embodiment of the present invention.
3 is a graph of electrical resistance change according to the carbon nanotube input amount according to the present invention.
Figure 4 is a comparative photograph of the gloss and contamination measurement of the surface according to the present invention.
Figure 5 is an explanatory diagram for measuring the electrical volume resistance of the PTFE+MWCNT composite according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

Prior to the description of the present invention, the following specific structures or functional descriptions are merely exemplified for the purpose of illustrating the embodiments according to the concept of the present invention, and the embodiments according to the concept of the present invention may be implemented in various forms, It should not be construed as being limited to the embodiments described herein.

In addition, embodiments according to the concept of the present invention can be applied to various changes and may have various forms, so specific embodiments will be illustrated in the drawings and described in detail herein. However, this is not intended to limit the embodiments according to the concept of the present invention to a specific disclosure form, and it should be understood that it includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The present invention provides a method of manufacturing a PTFE-CNT composite material having an electrical conductivity function by combining carbon nanotubes (CNT) for imparting electrical conductivity to PTFE (polytetrafluoroethylene).

At this time, PTFE has a molecular formula such as (C ₂ F ₄ )n, and is a material having excellent chemical resistance, non-adhesiveness, antifouling properties, heat resistance, and friction characteristics, and CNT imparts insufficient electrical conductivity in PTFE. Make it conductive.

Therefore, the present invention can provide a composite material having excellent electrical conductivity such as metal while maintaining the basic properties of PTFE.

However, since PTFE is a crystalline resin having the best chemical resistance and no particles, compatibility with other materials is very difficult, and electrical insulation is very excellent, so it is not easy to impart electrical conductivity to it.

On the other hand, to replace metal, the electrical resistance must be low (<1.0E+00Ω.㎝ Volume Resistivity).

1 is a classification comparison of the electrical resistance of the composition to impart electrical conductivity to the polymer resin.

A typical polymer resin is a volume resistivity (hereinafter referred to as ``electrical resistance'') as an insulator (<1.00E+13Ω.cm~1.00E+14Ω.cm↑), and is charged with an electrically conductive filler to the polymer resin. Dissipative, electrical resistance of electrical resistance (l.00E+04Ω.cm~1.00E+06Ω.cm), electrical resistance of resistance (1.00E+07Ω.cm~1.00E+12Ω.cm) (1.00E+01Ω.㎝~1.00E+3Ω.㎝) is classified as a use of a conductor, and existing compositions in which a conductive filler is added to a polymer resin correspond to this.

Here, the electrical resistance of a typical PTFE resin shows (1.0E+15Ω.cm ↑) characteristics.

However, since the electric resistance to replace the metal requires 1.00E+00Ω.cm or less, it has been impossible to achieve low electrical resistance (Volume Resistivity of 1.0E+00Ω.cm~1.0E-02Ω.cm). The composite material produced according to the PTFE-CNT composite material manufacturing method by (1.00E-01Ω.㎝~1.00E-02Ω.㎝ Volume Resistivity) realized electrical resistance.

(1.0E+00Ω.cm ~ 1.0E-02 ohm):1.0 is an integer in the above-mentioned resistance mark, + indicates not, 00~ is 10 to 0 power, -02 to 10 minus 2 power. .

In order to impart electrical conductivity to PTFE (Polytetra fluoroethylene) polymer materials by applying a method for imparting electrical conductivity to general polymer resins, one or more carbon-based carbon black, carbon nanotubes, graphene, graphite, etc. However, it is a reality that synthesis is very difficult, and there are no domestic material producers.

In terms of competition, there is no composite material made of PTFE and CNT in the world yet, so it cannot be compared directly, but the most leading company in this field can be seen as Saint Gobain, France.

St. Gobain uses Carbon Black as its conductive material, which is problematic for use in high-clean areas due to particles. The specification of the conductive PTFE product of Govine is 3 times ohm in electrical resistance, showing a lot of difference from -2 ohm which can be used as a metal substitute.

In addition, other companies include Dyneon, which has durability and application limitations because the material is in the form of ink (INK) using carbon black.

In addition, graphene, carbon black, graphite, carbon fiber, etc. are inferior to carbon nanotubes in terms of electrical conductivity, and a large amount of conductive particles must be injected to connect electrons to each other, so the basic properties of PTFE are Falling, problems such as abrasion and contamination occur, and in the electrically conductive region, carbon nanotubes and one or more substances have a good effect of mixing, but when mixing is used, contamination by short circuit occurs.

In addition, the PTFE product of Gobine Corporation is (<1.0E+03Ω.㎝ Volume Resistivity) or more, so it does not have electrical conductivity enough to replace metal, so it is difficult to use in places such as materials in the sensor field that require sensitivity. There are many limitations in the field.

Therefore, the present invention solves the contamination problem caused by abrasion, etc. by selecting carbon nanotubes alone as a conductive filler, and solving the electrical conductivity problem by grafting the carbon nanotubes and PTFE into a matrix. It is configured to solve the contamination problem caused by short circuit while maximizing the electrical conductivity by CNT, especially MWCNT, which is combined with PTFE on (Matrix).

Here, the carbon nanotube (CNT) may be a single-walled carbon nanotube or a multi-walled carbon nanotube, but a multi-walled carbon nanotube (MWCNT) was used in terms of cost-effectiveness.

In addition, the graft reaction refers to copolymerization of one linear polymer with another type of polymer in a branched state, and the resulting polymer is called a graft polymerization product.

More specifically, PTFE must be modified to remove F from the C-F bond of PTFE, which is difficult to use, and to permanently fix CNT (ie, C) by grafting.

In other words, it should be made to be able to react, and the state should be made to make the particle size of the PTFE less than or equal to the size, and also, by maintaining the surrounding environment (temperature and pressure) constant, stirring for a certain period of time to perform graft reaction. It is possible to obtain the desired PTFE-CNT, more preferably a PTFE-MWCNT composite material.

At this time, additives and catalysts may be used to promote the graft reaction.

However, if it does not meet a specific condition, that is, it is sensitive to temperature due to the characteristics of PTFE, so it must be careful because the quality deviation is severe and defects occur.

Here, the condition for modifying PTFE to the state in which the reaction can be made is to make the particle size 0.5 µm or less, and the pressure during the reaction should be 10-20 N/cm 2 and the temperature should be maintained at 50-100°C.

In this case, the method of making the PTFE particle size to 0.5 µm or less is usually made by cutting PTFE particles having a size of 10-50 µm with a polar organic solvent (solvent), which is naturally made by stirring in a container.

Polar organic solvents used for this use N-Methyl-2-pyrrolidone (NMP) with lithium bromide added.

At this time, lithium bromide is added to NMP in a weight ratio of 0.5:9.5, and NMP is a polar solvent, which increases the resolution of pores in the particles of PTFE, thereby cutting the particle size to be small.

In addition, the pressure and temperature must be maintained to promote the graft reaction while continuously maintaining the particle size.

In addition, CNTs for imparting electrical conductivity to PTFE in the present invention, especially MWCNTs, must have a specific degree of dispersion. For example, in the case of the present invention, CNTs dispersed at 5-15 nm should be used to obtain desired electrical conductivity characteristics.

By the way, CNT has a hexagonal honeycomb-shaped graphene sheet, which is rounded to a size of several nanometers in diameter to form a tube, and has different properties according to the dried direction and shape.

These CNTs are divided into Sing Walled CNT (SWCNT), Double Walled CNT (DWCNT), Multi Walled CNT (MWCNT), and Nanotube Rope according to the number of external walls.

In the present invention, it is preferable to utilize MWCNT, which is relatively inexpensive while being able to realize excellent electrical conductivity characteristics.

However, CNTs (including MWCNTs) easily agglomerate easily due to their very low dispersion characteristics, and thus, when added simply, desired properties can be obtained. Therefore, in order to uniformly disperse in a stable state without aggregation or precipitation when CNT is added, it is necessary to provide a simultaneous affinity of the matrix of CNT and PTFE.

Examples of the CNT dispersion method include an ultrasonic method, a chemical treatment method, a surfactant treatment method, and a polymer wrapping method.

Here, the ultrasonic method is a method of uniformly dispersing and dispersing the CNT dilution solution with an ultrasonic device, but there is a problem of damage to the nanotube, occurrence of reaggregation, and the like.

In addition, the chemical treatment method is an acid solution treatment method in which a surface functional group is introduced on the surface with sulfuric acid or nitric acid, but is not widely used due to the cutting and low dispersion stability of CNT particles.

In addition, the surfactant treatment method is a method of inducing and dispersing an electrostatic repulsive force or a steric repulsive force after coating the CNT surface, so it is possible to maintain CNT intrinsic properties and has good dispersion stability, but it has a disadvantage of removing the surface surfactant in subsequent processes. Have

On the other hand, the polymer lapping method is suitable for the present invention because the dispersion efficiency is very high and the uniformity can be maintained because the CNT is mixed at the monomer level to produce a composite.

PP (polypropylene) is preferable as a polymer resin that can be used in such a polymer wrapping method.

At this time, how much to disperse MWCNT, that is, CNT for polymer wrapping is a very important factor. This is because the electrical conductivity varies depending on the degree of dispersion of CNTs.

In the present invention, since CNTs dispersed at 5-15 nm are required, CNTs having a particle size of 5-15 nm, in particular, 50% by weight of MWCNT, 40% by weight of polypropylene resin as a lapping agent and graphite (Graphite) to further increase the electrical conductivity properties A mixture consisting of 10% by weight is used.

At this time, the polypropylene resin is for dispersive induction of CNTs, and graphite is for enhancing electrical conductivity.

In addition, an anti-agglomeration agent should be added to prevent re-agglomeration of PTFE during the grafting reaction. As a preferred anti-aggregation agent, vinylidene fluoride and perfluoro-1,3-dioxole are mixed in a weight ratio of 1:1. Use that.

These vinylidene fluoride and perfluoro-1,3-dioxole inhibit fibrillation of PTFE and prevent it from reagglomerating.

In addition, C ₁₈ H ₂₄ N ₂ (N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) may be further added to prevent oxidation by heat.

Since the oxidation by heat reduces the quality, it can be prevented to maintain a uniform quality.

In addition, the additive C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti(Titanium(4+) dioctyl phosphate 2,2-bis[(allyloxy)methyl]-1-butanolate(1:3:1)) is added to accelerate the reaction. Can be added.

At this time, the additive C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti is the average molecular weight (Average mass): 1225.398 Da, the structural formula is as follows.

In summary, the manufacturing method according to the present invention includes PTFE, MWCNT and an organic solvent in a stirring chamber and stirred, and then a functional regulator (anti-agglomeration, anti-oxidation, additive) containing C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti as an additive. After input and stirring, the organic solvent is removed using a centrifuge to prepare a composite material.

At this time, a special heat-pressing stirrer is used, and the polymer material PTFE (Polytetra fluoroethylene) is multiplied to have electrical conductivity, which is a metal replacement resistance (<1.0E+00Ω.㎝~1.0E-2Ω.㎝ Volume Resistivity). PTFE-CNT having an electrical conductivity function that maintains the properties such as chemical resistance, abrasion resistance, high heat resistance, and high gloss of PTFE while synthesizing wall carbon nanotubes (MWCNT) is sufficient to replace metal, more preferably Will be able to provide PTFE-MWCNT composites.

2 is a manufacturing process diagram for explaining an embodiment of the present invention. The manufacturing method according to the present invention will be described in detail with reference to FIG. 2 as follows.

The PTFE-MWCNT composite material manufacturing method according to the present invention proceeds as follows based on 100% by weight.

(1) Preparation step of heating the stirring chamber temperature 30 ~ 60 ℃ (S10).

(2) 10-30% by weight of PTFE powder (10um~250um) is added to the stirring chamber, 1-10% by weight of the MWCNT mixture is added to the stirring chamber, and the rest is charged with NMP mixed with lithium bromide, a polar organic solvent. Raw material input step (S20).

Here, the MWCNT mixture is a mixture of 50% by weight of MWCNT having a particle size of 5-15 nm, 40% by weight of a polypropylene resin as a lapping agent, and 10% by weight of graphite.

(3) while controlling the stirrer pressure (10 to 20 N/cm 2) while controlling and driving the stirrer mixing screw to 5,000 to 15,000 rpm, and the stirring chamber to convert and drive 10-200 rpm in the opposite direction to the rotation direction of the mixing screw to stir 1 Next stirring step (S30).

(4) When the viscosity (Viscosity) inside the stirring chamber is 3,000 ~ 5,000 CPS, a mixture of vinylidene fluoride and perfluoro-1,3-dioxole in a weight ratio of 1:1 based on 100 parts by weight of the polar organic solvent 0.1-0.2 parts by weight; C ₁₈ H ₂₄ N ₂ 0.2-0.3 parts by weight and C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti 0.3-0.6 parts by weight of the functional control agent input step (S40).

(5) A second stirring step (S50) in which the functional control agent is added and then stopped by reacting and stirring for 30 to 60 minutes.

(6) The organic solvent removal step of removing the organic solvent in the liquid phase by transferring it from the stirring chamber to a centrifuge (S60).

(7) Low temperature drying step (S70) of managing the residual gas (<50PPM) of the composite material composition from which the liquid organic solvent is removed.

(8) In order to commercialize the composite material completed in the low-temperature drying step (S70), it may be pulverized to an appropriate size and commercialized as a powder, or may be commercialized as a sheet or a bar using powder.

Here, in the preparation step (S10), a PTFE powder, a MWCNT mixture, and a polar organic solvent are prepared as raw materials.

In this case, MWCNT may use single-walled carbon nanotubes, and preferably, multi-walled carbon nanotubes.

In addition, carbon nanotubes use MWCNT that has undergone dispersion treatment as a material having its own aggregation phenomenon.

That is, a dispersion-treated MWCNT having a weakened van der Waals force and eliminating agglomeration due to ambient temperature must be prepared, as described above.

In addition, in order to adjust the stirring chamber to a suitable temperature, in the experiment of the present invention, it was exemplified to adjust to 30-60°C, and the temperature was initially adjusted to about 30°C.

In the step of introducing the raw material (S20), a PTFE powder, a MWCNT mixture, and a polar organic solvent are introduced into the stirring chamber at an appropriate ratio.

The polar organic solvent is the same as described above, and the PTFE is introduced in a size of 10-50 µm, and the polar organic solvent is introduced and stirred to make the size less than 0.5 µm while weakening the van der Waals force of PTFE to primarily agglomerate. To prevent.

CNT uses a dispersion-treated multi-walled carbon nanotube (MWCNT) 5 to 15 nm in size.

In the first stirring step (S30), the rotating screw inserted into the stirring chamber and the stirring chamber itself are rotated to stir.

At this time, the temperature and pressure inside the stirring chamber should be properly adjusted.

The temperature starts stirring at about 10°C or higher set in the preparation step, and the pressure starts stirring at a pressure of about 1 atmosphere, that is, 10 N/cm 2.

In other words, in the initial start-up phase, stirring can be started under normal room temperature and atmospheric pressure without separately controlling pressure and temperature.

However, since the temperature rise and the pressure rise during stirring, it must be adjusted to maintain the experimentally determined temperature and pressure range.

Preferably, the temperature is increased to 10 to 30°C at the start of stirring, controlled so as not to exceed 100°C during stirring, and starts to be stirred at a pressure of 10N/cm 2 in the starting step, and the pressure at the time of stirring is adjusted to 20N at the end of stirring. Adjust the pressure to follow /cm2 and stir.

In the stirring method, the rotating screw inside the stirring chamber is rotated while varying the speed in the range of 5,000 to 15,000 RPM, and the stirring chamber is rotated while varying the speed in the range of 10 to 200 RPM.

At this time, the rotating screw inside the stirrer and the stirring chamber are rotated in opposite directions so that double reverse rotation is applied, so that the rotational pressure received by the substances being stirred inside is doubled, so that agitation is better.

The internal pressure and temperature are increased due to high-speed rotational agitation. The temperature and pressure can be adjusted by installing a temperature control means and a pressure control means in the stirring chamber, and controlling the stirring rotational speed.

In the step of introducing the functional control agent (S40), when the viscosity of the stirring material is a predetermined viscosity, re-agglomeration, that is, an anti-agglomeration agent that prevents secondary aggregation, an antioxidant that inhibits oxidation by heat, and an additive that promotes a graft reaction are respectively determined. Add the dose according to the recipe.

In this case, it is difficult to measure the viscosity of the substance being stirred inside the stirring chamber.

Therefore, the primary agitation time is determined by experimentally obtaining the primary agitation time in which the viscosity of the agitated raw material becomes 3,000 to 5,000 CPS corresponding to the total amount of the raw material input.

Accordingly, when the first stirring time corresponding to the total amount of the input raw material has elapsed, the viscosity of the agitated internal material is expected to be in the range of 3,000 to 5,000 CPS, and accordingly, when the first stirring time has elapsed, a functional control agent is added.

The second agitation step (S50) is a step of injecting a functional modulator to perform agitation reaction, and performs a second agitation step according to a recipe determined by experimentally obtaining temperature, pressure, and time. When the second agitation is performed, the solid absorbs gas and liquid to form an intermediate result in an 80% by weight paste state.

In the organic solvent removal step (S60), the intermediate product in the paste state produced by the stirring step is transferred to a centrifuge to separate and remove liquid and gas.

In the low temperature drying step (S70), the intermediate organic product in a liquid state is removed from the intermediate product, and the intermediate product in the paste state is dried at low temperature with dehumidification.

In this way, a desired composition can be obtained by making it in a bake state by drying at a low temperature.

Thereafter, the composition thus obtained is commercialized for use.

For example, it may be exemplified to pulverize the lumped composition in a bake state, or to extrude the powder into a sheet or rod compressed by crushing the powder into a sheet, or to commercialize the product in a desired shape.

Hereinafter, an example in which the characteristics of the composite material obtained according to the present invention is confirmed will be described.

3 is a graph of electrical resistance change according to the amount of carbon nanotube input according to the present invention.

In order to obtain a low resistance value, the weight percentage of the CNT mixture at a weight ratio of 100% is the electrical resistance volume resistivity 1.0E+00Ω.cm is 3-4% by weight, and the electrical resistance volume resistivity 1.0E- 02Ω.㎝ is preferably 4 to 6% by weight, and 7 to 10% by weight was added to obtain a lower resistance value, but the electrical resistance volume resistivity (1.0V) was not changed.

The target value of the experiment was expected to decrease the resistance value in proportion to increasing the input amount of the CNT mixture, but it was found that there was a convergence section with virtually no change in resistance.

That is, as shown in FIG. 3, when the CNT mixture is not added to the PTFE, the electrical resistance is 1.0E+14Ω.cm, and when the 5% by weight of the CNT mixture is added, the electrical resistance is 1.0E-01Ω.cm. When adding 6% by weight of CNT mixture, it was found that the electrical resistance was 1.0E-02Ω.cm, and when adding 7% by weight of CNT mixture, it was found that the electrical resistance value did not change even though the input amount increased as the electrical resistance was 1.0E-02Ω.cm. .

In this experiment, the CNT mixture had a maximum area of 6 to 7% by weight of 1.0E-02Ω.cm, and a convergence section in which electrical resistance did not change even when the addition amount increased was confirmed.

In addition, when the viscosity (Viscosity) inside the stirring chamber exceeds 3,000 CPS, a mixture of vinylidene fluoride and perfluoro-1,3-dioxole in a weight ratio of 1:1 based on 100 parts by weight of a polar organic solvent is 0.15 weight Wealth; 0.25 parts by weight of C ₁₈ H ₂₄ N ₂ was further added to prevent re-agglomeration of PTFE and oxidation by heat.

At the same time, in order to increase the affinity and reactivity between the interfaces of the PTFE and CNT mixture, 0.4 parts by weight of C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti, an additive that promotes reaction, that is, coupling, was added based on 100 parts by weight of a polar organic solvent, By maintaining the chamber temperature at 65°C and preparing a graft polymer for 10~20N/cm2 pressure, mixed screw 7,000RPM, and 45 minutes, the mechanical properties and physical properties of the existing foreign company's conductive PTFE (polytetrafluoroethylene) were compared. .

division
The tensile strength
kgf/㎠
ASTM D638
Flexural elasticity
kgf/㎠
ASTM D790
Impact strength
kqf/㎠
ASTM D256
importance
ASTM D792
Exterior
resistance
Ω.㎝
ASTM D257
existing
product
250 ~ 350
4,650
10-12
2.0 ~ 2.2
Great
1.0E+02 ~ 03
The present invention
product
400 ~ 500
5,800
11-13
2.0 ~ 2.2
Extremely
Great
1.0E-01 ~ -02

Here, the existing product is a conductive PTFE product of St. Gobain, France, and the present product manufactured by the present invention is compared with this existing product.

Compared to the product to which the conventional carbon black is added, the product according to the present invention has been improved in almost all measurement fields, and it has been found that, in particular, it has a low electrical resistance capable of metal replacement.

In the present invention, the composition was prepared with a sheet having a thickness of 0.3 mm, and a specimen was prepared by a conventional test method to test and compare tensile strength, flexural elasticity, impact strength and specific gravity, and visually judged the appearance and resistance of the specimen. It is the result of manufacturing and measuring through a measuring device.

As a result of experiment and comparison of the existing product with the present invention product, the tensile strength, flexural elasticity, and impact strength are superior to the existing product, the specific gravity is the same, the appearance is very excellent, and the resistance is especially incomparable to the existing product. It shows a large characteristic difference, and it was found that the resistance value for the purpose of replacing the metal was sufficiently implemented.

Figure 4 is a comparative photograph drawing of the gloss and contamination of the surface according to the present invention, Figure 5 is an explanatory diagram for measuring the electrical volume resistance of the PTFE-MWCNT composite material according to the present invention.

A 0.3 mm film was made of the composite material obtained according to the present invention, and the surface condition and the degree of contamination were measured and verified.

In the photo drawing of FIG. 4, the first conductive left PTFE in the first picture (A) was sampled with a conductive PTFE to which carbon black of an existing foreign company was added, which caused sludge caused by abrasion and short circuit of electrical conductivity. . In the middle photo (B), 2. CNT 5%+PTFE is a composite material synthesized by adding 5% by weight of CNT to PTFE. The surface condition was poor, such as white spots and pinholes appearing on the surface. .

3.CNT5%+PTFE+CA in the right photo (c) is 5% by weight of CNT mixture in PTFE and vinylidene fluoride and perfluoro-1,3-dioxole in a weight ratio of 1:1 in a functional control agent. 0.15 parts by weight of the mixture, 0.25 parts by weight of C ₁₈ H ₂₄ N ₂ and C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti as an additive were added to show the result of synthesis, and showed excellent results in surface roughness and dispersion contamination.

That is, when 5 wt% of the CNT mixture was added to the PTFE and synthesized, a functional modifier was added in a set amount, and the result of stirring and synthesis was able to obtain the best result.

division
▶Existing Conductive PTFE
▶CNT 5%
▶PTFE
▶CNT 5%
▶PTFE
▶Functional regulator
▶CNT 8%
▶PTFE
▶Functional regulator
Composition
Appearance roughness
○
Ｘ
◎
△
Composition
Internal cross section
○
Ｘ
◎
△
Composition
Roughness, pollution
Ｘ
△
◎
△

-Composition evaluation comparison (◎: very good, ○: good, △: normal, Ｘ: bad)

Here, the existing conductive PFTE is a sample of conductive PTFE added with carbon block of Govine.

The exterior roughness visually inspected the external appearance of each sample sheet, the internal cross-section was checked, and the roughness and contamination level were the lighting reflectance, and the contamination level was when the surface was rubbed to see if there was contamination. Was tested.

In addition, although not indicated in the table, whether the short circuit contamination, that is, the electrical conductivity is uniform, was tested by measuring the electrical conductivity at each position of the entire area of the sheet using the measuring contact as shown in FIG.

To measure the electrical volume resistance of the PTFE-CNT composite material according to the present invention, a sheet having a thickness of 0.3 mm was prepared as shown in Fig. 5(A), and a specimen was prepared with a width of 1 inch, that is, 15 cm X 10 cm X 0.3 mm, , Remove foreign substances on the surface. Subsequently, a low-resistance meter (HIOKI M-3548) as in the second photo of (B) was used, and the volume resistance within 1 inch/sq was measured according to the ASTM D257 measurement method. The resistance of the measuring table was 1.0E+14Ω.㎝ The above conditions were maintained.

Specimens prepared by the present invention, that is, 5% by weight of CNT and functional control agent added to the PTFE, the results of measuring the specimens of the composite material prepared by stirring with the above measuring method, the results of 1.0E-02Ω.cm Got.

S10: Preparation stage S20: Raw material input stage
S30: 1st stir step S40: Function modulator input step
S50: 2nd stirring step S60: Organic solvent removal step
S70: drying step

Claims (8)

Preparation step of heating the stirring chamber temperature 30 ~ 60 ℃;
A raw material input step of adding 10 to 30% by weight of PTFE powder, 1 to 10% by weight of CNT mixture, and NMP mixed with lithium bromide as a polar organic solvent to the stirring chamber based on 100% by weight;
A first stirring step of stirring for a stirring time proportional to the total amount of raw material input while controlling the temperature and pressure of the stirring chamber within a preset range;
When the viscosity (Viscosity) inside the stirring chamber is 3,000 to 5,000 CPS, a mixture of vinylidene fluoride and perfluoro-1,3-dioxole in a weight ratio of 1:1 based on 100 parts by weight of the polar organic solvent 0.1-0.2 Parts by weight; C ₁₈ H ₂₄ N ₂ 0.2-0.3 parts by weight and C ₆₀ H ₁₂₃ O ₁₅ P ₃ Ti 0.3-0.6 parts by weight of functional control agent input step;
Secondary stirring step to stop by reacting and stirring for 30 to 60 minutes after adding the functional regulator;
An organic solvent removal step of removing the liquid organic solvent after the second stirring;
PTFE-CNT composite material having electrical conductivity, characterized in that produced by a manufacturing method comprising; low-temperature drying step of preparing a composite material is CNT-synthesized to PTFE by drying the composition with the liquid organic solvent removed at a low temperature.
According to claim 1,
PTFE-CNT having electrical conductivity, characterized in that the resultant produced in the low-temperature drying step is pulverized to produce a product of any one of powder, sheet, film, or bar. Composite material.
According to claim 1,
The CNT mixture introduced in the raw material injection step is 50% by weight of MWCNT having a particle size of 5-15nm, and electrical conductivity characterized by using a mixture consisting of 40% by weight of a polypropylene resin as a wrapping agent and 10% by weight of graphite. Having PTFE-CNT composite material.
According to claim 1,
The primary and secondary stirring steps,
Mixing screw rotating step of rotating the mixing screw inserted into the stirring chamber,
PTFE-CNT composite material having electrical conductivity, characterized in that the stirring chamber rotating step of rotating the stirring chamber in the opposite direction to the mixing screw at the same time.
According to claim 4,
The primary and secondary stirring steps,
The mixing screw is rotated at a high speed of 5,000 ~ 1,5000 RPM, the stirring chamber is PTFE-CNT composite material having electrical conductivity, characterized in that rotating at a low speed of 1 ~ 200 RPM.
According to claim 4,
The primary and secondary stirring steps,
PTFE-CNT composite material having electrical conductivity, characterized in that the rotation of the mixing screw and the rotation speed of the stirring chamber are varied while stirring.
According to claim 4,
The stirring chamber rotating step, PTFE-CNT composite material having electrical conductivity, characterized in that the on/off is repeatedly controlled by an intermittent rotation method.
According to claim 1,
In the raw material injection step, the polar organic solvent is a lithium-bromide and NMP (N-Methyl-2-pyrrolidone) is a PTFE-CNT composite material having electrical conductivity, characterized in that the solvent is mixed in a weight ratio of 0.5:9.5.

Images