KR102075923B1 - metal CNT Polymer Composite and Manufacturing Method - Google Patents

Abstract

A method of manufacturing a low resistance (Ω) Al-CNT polymer composite material by using aluminum oxidation expansion according to the present invention comprises: a first step of oxidizing the surface of an aluminum powder; a second step of settling the surface-oxidized aluminum powder and a CNT powder into an organic acid solution to mix the surface-oxidized aluminum powder and the CNT powder with the organic acid solution; a third step of hot-pressing the material of the second step to manufacture an Al-CNT plate shaped pellet, and drying the Al-CNT plate shaped pellet to pyrolyze an organic acid; a fourth step of producing an Al-CNT polymer composite material by compounding the Al-CNT plate shaped pellet manufactured by the third step with polymer plastics; a fifth step of forming a polymer composite electrode catalyst for water electrolysis by using an electroconductive Al-CNT polymer composite material manufactured in the fourth step; and a sixth step of oxidation-expanding and aging an aluminum powder in the polymer composite electrode catalyst by anodic oxidation method. The method according to the present invention has effects of improving dispersibility of CNT and enabling contact point of CNT due to oxidation expansion to be reinforced in the polymer by using oxidation characteristics of the aluminum powder.

Description

Manufacturing method of low-resistance Al-CNT polymer composite material using aluminum oxide expansion, manufacturing method of polymer composite electrode catalyst for water electrolysis and its products {metal CNT Polymer Composite and Manufacturing Method}

The present invention relates to a low-resistance Al-CNT polymer composite material that can replace the electrolytic platinum group (platinum, ruthenium, rhodium, iridium, titanium, etc.) electrode catalyst, and more specifically, Al, Ti MW-CNT dispersibility is improved in the polymer by oxidizing properties of metal powder, Mg, Zn, etc., and the contact of CNT network structure by oxidative expansion of metal powder in polymer when applied as water electrolysis catalyst It relates to a method for producing a polymer composite electrode catalyst for water electrolysis that can be improved.

Recently, many systems and equipment have been developed to produce hydrogen by water electrolysis as an alternative to the hydrogen energy industry to replace hydrogen fueled cars and limited fossil fuels and to solve the global warming problem caused by greenhouse gases.

Conventionally, as an electrocatalyst for water electrolysis, it has been manufactured using expensive platinum (Pt), ruthenium (Ru), rhodium (RH), iridium (Ir) and various other metals. There is a limit.

In addition, the CNT of the existing metal powder is dispersed, coated and sintered to be used as a metal-based addition to Zn, tin, copper, etc., or developed and applied as a thermally conductive metal CNT composite material. It is limited and difficult to use as a water electrolysis electrocatalyst to replace the platinum-based electrocatalyst.

Recently, there are many materials in which CNTs are dispersed in polymer materials, but most of them are used for coating or master batch. Due to van der Waals effects, CNTs have a high content (more than 25%) when compounding with polymer materials. there was.

In addition, as the surfactant used as the CNT dispersant escapes, the performance of the electrocatalyst for water electrolysis is drastically reduced, and the contact resistance between the CNT and the CNT is increased, which may be an issue of use as an electrode catalyst requiring low performance. It is difficult to add a high content of CNT to CNTs by mechanical dispersion, or unmolded or deteriorated physical properties during injection of low-resistance and electrically conductive polymer plastics.

Therefore, there is a need for a polymer plastic electrode catalyst having excellent productivity and economical efficiency as a new alternative.

KR Patent Publication No. 10-1666881 (2016.10.11) KR Patent Publication No. 10-1666884 (2016.10.11)

The present invention was devised to solve the same problem as before, utilizing the oxidation characteristics of metal powders such as Al, Ti, Mg, Zn to improve the dispersibility of CNTs and improve the contact point of CNTs due to oxidative expansion in polymers. It is an object of the present invention to provide a method for producing a low-resistance Al-CNT polymer composite material using a metal oxide expansion that can be strengthened and a method for preparing a polymer composite electrode catalyst for water electrolysis.

Low-resistance Al-CNT polymer composite material manufacturing method using aluminum oxide expansion according to the present invention for achieving the above object,

A first step of oxidizing the aluminum powder surface;

A second step of precipitating and mixing the surface-oxidized aluminum powder and the CNT powder of the first step into an organic acid solution;

A third step of thermally compressing the material of the second step to prepare Al-CNT plate-shaped pellets and drying to pyrolyze the organic acid;

A fourth step of compounding the Al-CNT plate-shaped pellet prepared by the third step and the polymer plastic to produce an Al-CNT polymer composite material; Characterized in that it comprises a.

In addition, a fifth step of molding into a polymer composite electrode catalyst for water electrolysis using the electrically conductive Al-CNT polymer composite material prepared in the fourth step;

A sixth step of oxidatively expanding and aging the aluminum powder in the polymer composite electrode catalyst by anodizing; It characterized in that it further comprises.

In addition, the aluminum powder of the first step is characterized in that the particle size of 10 ~ 60㎛.

In addition, the CNT powder of the second step is 60 to 80% by weight, aluminum powder is mixed in a ratio of 20 to 40% by weight dry weight, while precipitated aluminum powder in an organic acid solution and stirred with agitator RPM 5 ~ 10, CNT powder After 60 to 80% by weight, it is characterized by mixing by stirring for 10 to 20 minutes.

In addition, the thermal compression roll interval of the third step is 1mm, the diameter of the roll is 150mm, proceeds twice at a speed of 3 to 5 RPM at 190 ~ 200 ℃ temperature, the residual moisture content at the chamber temperature 100 ~ 120 ℃ It is characterized by drying to 2 to 4% by weight.

In addition, the polymer plastic material of the fourth step is one selected from PP, PE, SEBS with excellent chemical resistance, but mixed 60 to 70% by weight of the polymer plastic material, 30 to 40% by weight of Al-CNT plate pellets After extruded at a twin extruder temperature 200 ~ 240 ℃ characterized in that the hot cut to a size of 3 ~ 5mm.

In addition, after binding the polymer composite electrode catalyst of the sixth step to one (+) pole and one sheet to the (-) pole at a 2 mm interval, 10 wt% (1000 g) of citric acid was added to 10 l of water in a plastic container. Prepare a citric acid electrolytic solution with a water temperature of 25 ℃, install a combined electrode catalyst, apply a voltage of DC12V, and set the power supply time to 30 to 60 minutes, and replace the (+) and (-) poles again. The total time is 60 to 120 minutes by electrolysis of 30 to 60 minutes, characterized by anodizing and expanding from the aluminum powder dispersed on the polymer surface to the inside.

The method for producing low-resistance Al-CNT polymer composite material and the method for preparing polymer composite electrode catalyst for water electrolysis using aluminum oxide expansion according to the present invention improve the dispersibility of CNT by utilizing the oxidation characteristics of aluminum powder. There is an effect that can strengthen the contact point of the CNT due to oxidative expansion in the polymer.

1 is a process chart showing a low-resistance Al-CNT polymer composite material manufacturing process using aluminum oxide expansion according to the present invention.

Hereinafter, a method of manufacturing a low resistance Al-CNT polymer composite material using aluminum oxide expansion according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a process chart showing a low-resistance Al-CNT polymer composite material manufacturing process using aluminum oxide expansion according to the present invention, the aluminum powder surface oxidation step as shown in the figure; Surface oxidation-treated aluminum powder and CNT powder mixing step; Al-CNT platelet pellet preparation and citric acid pyrolysis step; Extrusion pellet production step after compounding with polymer plastic; Preparing an electroconductive electrocatalyst for water electrolysis; Electrocatalyst binding aging step; It includes.

[First Step] Aluminum Powder Surface Oxidation Step

The specific gravity of the metal powder is aluminum (AL) of 2.7, titanium (Ti) of 4.51, magnesium (Mg) of 1.74, and zinc (Zn) of 7.1. use. Platinum group metals such as platinum (Pt), iridium (Ir), rhodium (Rh), ruthenium (Ru), and osmium (Os) are limited in production and expensive. Iron (Fe) and copper (Cu) When water electrolysis, the oxidized portion may be precipitated to cause a problem or internal pores may be generated to drastically reduce the physical properties of the electrode catalyst. All metals are partially oxidized in the atmosphere, but it is difficult to improve the aggregation of light-weight CNTs by van der Waals forces.

When the particle size of the metal powder is 10 μm or less, the oxidation expansion rate is weak in the polymer during natural oxidation and oxidation during the manufacturing process, thereby weakening the contact strengthening of the CNT and the CNT, and when the particle size is 60 μm or more, when mixed with CNT It can be separated by the difference in specific gravity.

Using 10 to 60 μm of particles of the metal powder improves CNT dispersion of the high content in the polymer, such as ball milling, in which the metal powder in the polymer is extruded and injected under pressure during the extrusion.

In addition, nano-size metal powder is mixed between the CNT and the CNT layer can be used for coating, but the use of the characteristics of oxidative expansion is weak.

Al, Ti, Mg and Zn of nano particle size have difficulty in reinforcing the strength of crosslinked junction between CNT and CNT by using the effect of oxidative volume expansion when used as water electrolysis electrocatalyst in polymer due to complete oxidation during working process have.

Surface oxidation treatment of the metal powder may be used by preparing an organic acid, but using one or two or more solutions of citric acid, malic acid, succinic acid and succinic acid. In the present invention, aluminum (Al) is used as the metal powder and citric acid is used as the organic acid.

The ratio of aluminum powder to CNT is 20 to 40% by weight of dry aluminum powder and 60 to 80% by weight of CNT powder. Here, if the aluminum powder is less than 20% by weight, the oxidative expansion is weak in the polymer to weaken the contact between the CNT and the CNT. If the aluminum powder is more than 40% by weight, the CNT content is relatively low, thereby increasing the surface resistance of the electrode catalyst. It may worsen the electrical conductivity.

[Step 2] CNT and Aluminum Powder Mixing Step

In 100 ml of water, a citric acid solution is prepared at a water temperature of 20 to 30 ° C. Citric acid powder content is 1 to 2% by weight, wherein the pH is 2.25 ~ 2.32 is produced with a weak acidity, but the surface oxidation degree of aluminum powder reveals that the pH can be adjusted according to the temperature, time and the like. Using citric acid solution is distinguished from anodizing and expanding the cell stack after the second and sixth steps.

First, the aluminum powder dry weight 20 to 40% by weight to 60 to 80% by weight of the citric acid solution is precipitated in the citric acid solution, while stirring with agitator RPM 5 to 10, divided into 60 to 80% by weight of CNT powder after 10 to 20 minutes Stir and mix. CNT is MW-CNT with a CNT content of 98 to 100% by weight, because CNT residual catalysts Fe, Co, Ni, etc. may be a problem due to precipitation during water electrolysis, it is preferable to use CNTs with less residual catalyst. At this time, if the citric acid solution is less than 60% by weight citric acid solution absorption in the aluminum powder and CNT powder may be weak, the drying time may be longer if the citric acid solution is more than 80% by weight.

[Step 3] Al-CNT Plate Pellet Preparation and Citric Acid Pyrolysis Step

Al-CNT plate-like pellets are produced by the material of the second step through a thermocompression roll. The thermal compression roll spacing is 1mm, the diameter of the roll is 150mm, and proceeds twice at RPM 3-5 speed at a temperature of 190 ~ 200 ℃. At this time, Al-CNT plate-like pellets may be broken when only one time progresses, and when the two or more times progresses, the compressive strength may be increased, thereby causing a problem in dispersion.

The Al-CNT plate-shaped pellets are dried at a chamber temperature of 100-120 ° C. such that the residual moisture content is 2-4% by weight. At this time, some water is removed, and the organic acid citric acid is thermally decomposed. Pyrolysis of citric acid can be further removed during extrusion and injection, which will be described later, Al-CNT plate-like pellets may be broken when the water content is 2% by weight or less and CNT due to moisture during the extrusion of the polymer material and compounding by more than 4% by weight. The interface can be weakened to the polymer resin.

During the thermal compression roll process and the drying process, the aluminum powder has a slight surface oxidation, and the Al-CNT platelet pellet is a surface oxide expanded aluminum having amphoteric ions since the aluminum powder between CNT and CNT is additionally oxidized. This improves agglomeration of CNTs and dispersibility in polymers. At this time, the size of the Al-CNT plate-like pellets are irregular sizes in the thickness of 1mm, the size of about 0.1 ~ 5mm around.

[Step 4] Al-CNT polymer composite production step after compounding with polymer plastic

Compounding the Al-CNT plate-shaped pellets and the polymer plastic produced by the third step to produce an Al-CNT composite material. Here, the polymer plastic material uses one of PP, PE, and SEBS having excellent chemical resistance. In the present invention, PP is used.

That is, after mixing 60 to 70% by weight of PP, 30 to 40% by weight of Al-CNT platelet pellets and extrusion at a twin extruder temperature of 200 ~ 240 ℃ hot-cut to 3 ~ 5mm size to produce an Al-CNT composite material. At this time, when Al-CNT platelet pellet is more than 40% by weight, CNT present in the platelet pellet becomes 32% by weight of high content CNT, which may be difficult or unmolded, and Al-CNT platelet pellet is 30% by weight. If it is less than the CNT content may be poor surface electrical conductivity. Pellet cutting is hot-cutting because water may penetrate into the CNTs when water-cooled.

[Fifth Step] Electrocatalyst Molding Step for Water Electrolysis

The electroconductive Al-CNT polymer composite material prepared in the fourth step prepares a polymer composite electrode catalyst for water electrolysis having a thickness of 4 mm, a width of 110 mm, and a length of 110 mm at an injection machine screw temperature of 220 ° C. to 240 ° C. The polymer composite electrode catalyst for water electrolysis may be manufactured by designing different shapes, sizes, and sizes according to water capacity, use, and container.

[Sixth Step] Electrocatalyst Binding Step

Oxidative expansion and aging of the aluminum powder in the polymer composite electrode catalyst by the anodic oxidation method. By reducing the contact resistance of CNT and CNT and strengthening the CNT-polymer interface, it is possible to improve acid resistance, chemical resistance, and electrical conductivity, and to obtain a constant and stable current (2A).

From the aluminum powder dispersed on the surface of the polymer composite electrode catalyst, oxidation expansion proceeded and citric acid among organic acids was used.

The polymer composite electrode catalyst prepared in the above step is bound to one sheet on the (+) pole and one sheet on the (-) pole at 2 mm intervals, and then 10 wt% (1000 g) of citric acid is added to 10 l of water in a plastic container to give a water temperature. A citric acid electrolytic solution at 25 ° C. was prepared, and a combined electrode catalyst was applied thereto and then a voltage of 12 V DC was applied. At this time, the power application time is 30 ~ 60 minutes, and the (+) and (-) poles are replaced, and electrolysis is again performed for 30 to 60 minutes, and the total time is 60 to 120 minutes. Anodic oxidation expands inward. Here, the organic acid may be used in addition to citric acid, but other organic acids may be used. The solution of 10 wt% citric acid may be PH 1.68, and the pH may be about 1.5 to 1.8. In addition, the use of the inorganic solution may weaken the function of the electrode catalyst due to the deterioration of physical properties of the polymer plastic due to strong acidity during anodization.

At this time, the surface anodic oxidation thickness of the aluminum powder particles dispersed in the polymer plastic is 2 ~ 6㎛, the contact surface portion with the water is 6㎛, and toward the inside of the polymer from 4㎛ to 2㎛ as the aluminum powder particles relative to the center of the electrode catalyst As little as 2㎛ around. This is because anodic oxidation proceeds rapidly from the surface as the current penetrates the entire metal plate and the solution penetration into the polymer decreases relatively.

The support for holding aluminum powder and CNT is a polymer plastic made of thermoplastic PP material. Excessive anodic oxidation time may swell or exfoliate the plastic surface, thereby weakening the electrocatalyst function.

The anodic oxidation aging time of the polymer composite electrode catalyst should not exceed 60 minutes, and surface cracking or peeling may occur due to internal stress and pressure during aluminum oxide expansion in a short time. In addition, after anodic oxidation, the anodic oxidation gradually increases during water electrolysis to maintain stability in the continuous electrode catalyst. If the anodization aging time is less than 30 minutes, the change in the current (A) when the power is applied is difficult to stable control.

The present invention can maintain a stable and stable surface electrical conductivity of the electrode catalyst inside the electrode catalyst in the above manner with excellent corrosion resistance and oxidation resistance, CNT maximizes a large surface area in the CNT by the microstructure and porous composition in the surface layer in contact with water You can.

[Comparative 1]

Comparison of Properties of Polymer Plastic PP with CNT Content

The present invention is tested by injection molding the following ratio condition thickness 4mm, horizontal 110mm, vertical 110mm size based on the data.

Rate condition

Al-CNT Plate Pellet Manufacturing Rate

1st step: Aluminum powder dry weight 20 ~ 40% by weight, CNT dry weight 80 ~ 60% by weight

Step 2: Based on the ratio of Al-CNT plate pellets prepared in step 1

A: When 40 weight% of Al-CNT sheet pellets and 60 weight% of PP

B: 20 wt% of aluminum powder, 40 wt% of aluminum powder, 32 wt% of CNT, 8 wt% of aluminum powder

40% by weight of aluminum powder, 40% by weight of CNT content, 24% by weight of CNT content and 16% by weight of aluminum powder.

D: 25% by weight of CNT, 75% by weight of PP

Measurement of surface resistance and weight on square plate before anodization

CNT content (% by weight) Surface resistance B CNT 32 / Aluminum Powder 8 0.18 C CNT 24 / Aluminum Powder 16 0.24 D CNT 24 / Aluminum Powder Zero 0.37

The data is the average value measured five times, the product is difficult to realize the unmolded when the CNT content of more than 25% by weight of the D conditions, and the aluminum powder CNT composite material of B is not as D when the maximum CNT content of 32% by weight or more Molding was obtained.

In addition, the internal density and weight was excellent in the aluminum powder of C No. 16 weight percent, but the electrically conductive surface resistance that can improve the performance was excellent in 32 wt% CNT No. B.

[Comparative 2]

Surface resistance change before and after anodizing at 60 minutes

All (Ω / □) After (Ω / □) B 0.18 0.16 C 0.24 0.21 D 0.37 0.46

5 measurement average

Comparative test results of before and after oxidation aging to electrode catalyst by citric acid solution

The number D of the aluminum powder is zero, which increases the surface resistance from 0.37Ω / □ to 0.46Ω / □ after 60 minutes due to the acidic nature of the citric acid solution. C can improve the function of the electrode catalyst by enhancing the contact between CNT and CNT due to the oxidative expansion of aluminum powder and improving the surface resistance from 0.24Ω / □ to 0.21Ω / □.

[Experiment 1]

In the experiment 2, 4000g of 25 ℃ tap water (TDS: 110ppm) was put in an insulation container after anodizing and the DC 12V was applied to change the current (A) for 28 days. The catalyst electrodes were bonded to each of the (+) and 1 (-) poles at 2mm intervals, respectively, and then proceeded without reversal to the electrodes (+ and-poles). Metal catalyst coated with ruthenium (Ru) 1.5㎛ at 110mm horizontally and 110mm vertically.

In addition, the electrolysis of water is relatively increased due to the amount of electrolyte in the water according to the amount of hydrogen, oxygen and may vary slightly due to the temperature change of the water.

First (A) 7 days (A) 14 days (A) 21 days (A) 28 days (A) Average A Down B 1.29 1.27 1.26 1.25 1.24 3.5% C 1.05 1.04 1.04 1.03 1.02 2.3% D 0.81 0.73 0.65 0.57 0.62 23.5% E 1.13 1.02 0.98 0.95 0.92 18.2%

Three sets of each were prepared and averaged after three repeated experiments, and water was replaced with a 1 day cycle.

As a result of experiments B and C, the oxidative expansion of aluminum powder strengthened the contact between CNT and CNT, and improved the performance of stable surface current and polymer plastic electrode catalyst.

After 28 days, D had no aluminum powder and the current decreased by 23.5%, E decreased by 18.2%, and the electrocatalyst performance decreased, and C, which has a high aluminum powder content of B and C, was more stable than B. It became.

In addition, the E-catalyst, which is a metal-based electrode catalyst, has a problem of weakening the water electrolysis function and reversing the electrode (+ pole,-pole) within at least 15 minutes as various mineral components are adsorbed and cured in water (H 2 O). In case of C, it can be seen that various minerals and foreign substances are not cured due to CNTs and polymer properties of carbon components, and thus sustaining efficacy can be maintained.

Claims (10)

A first step of oxidizing the aluminum powder surface;
A second step of precipitating and mixing the surface-oxidized aluminum powder and the CNT powder of the first step into an organic acid solution;
A third step of thermally compressing the material of the second step to prepare Al-CNT plate-shaped pellets and drying to pyrolyze the organic acid;
A fourth step of compounding the Al-CNT plate-shaped pellet prepared by the third step and the polymer plastic; Low-resistance Al-CNT polymer composite material manufacturing method using aluminum oxide expansion, comprising a.
According to claim 1,
60 to 80% by weight of the CNT powder of the second step, aluminum powder is mixed at a ratio of 20 to 40% by weight of dry weight, CNT powder 60 ~ while stirring the precipitated aluminum powder in an organic acid solution with agitator RPM 5 ~ 10 After adding 80% by weight, mix by stirring for 10-20 minutes,
In the fourth step, the polymer plastic material is selected from PP, PE, and SEBS having excellent chemical resistance, but is mixed with 60 to 70% by weight of the polymer plastic material and 30 to 40% by weight of Al-CNT plate pellets. A low resistance Al-CNT polymer composite material manufacturing method using aluminum oxide expansion, characterized in that the hot-cut to 3 ~ 5mm size after extrusion at an extruder temperature 200 ~ 240 ℃.
A first step of oxidizing the aluminum powder surface;
A second step of precipitating and mixing the surface-oxidized aluminum powder and the CNT powder of the first step into an organic acid solution;
A third step of thermally compressing the material of the second step to prepare Al-CNT plate-shaped pellets and drying to pyrolyze the organic acid;
A fourth step of compounding the Al-CNT plate-shaped pellet manufactured by the third step and the polymer plastic to produce the Al-CNT polymer composite material;
A fifth step of molding the polymer composite electrode catalyst for water electrolysis using the electrically conductive Al-CNT polymer composite material prepared in the fourth step;
A sixth step of oxidatively expanding and aging the aluminum powder in the polymer composite electrode catalyst by anodizing; Method for producing a polymer composite electrode catalyst for water electrolysis comprising a.
The method of claim 3, wherein the aluminum powder of the first step has a particle size of 10 μm to 60 μm.
According to claim 3, wherein the CNT powder of the second step is 60 to 80% by weight, the aluminum powder is mixed in a ratio of 20 to 40% by weight dry, first precipitate the aluminum powder in an organic acid solution and then agitator RPM 5 ~ 10 Method for producing a polymer composite electrode catalyst for water electrolysis, characterized in that by stirring for 10 to 20 minutes after adding 60 ~ 80% by weight of CNT powder while stirring.
According to claim 3, wherein the thermocompression roll is used during the thermal compression of the third step, the thermal compression roll interval is 1mm, the diameter of the roll is 150mm, two times at a speed of 3 ~ 5 RPM at 190 ~ 200 ℃ temperature The process for producing a polymer composite electrode catalyst for water electrolysis, characterized in that for drying, so that the residual moisture content is 2 to 4% by weight at a chamber temperature of 100 ~ 120 ℃.
According to claim 3, wherein the polymer plastic material of the fourth step is selected from PP, PE, SEBS of the excellent chemical resistance, using 60 to 70% by weight of the polymer plastic material, Al-CNT plate pellets 30 to 40 weight Method for producing a polymer composite electrode catalyst for water electrolysis characterized in that the hot-cut to a size of 3 ~ 5mm after extrusion at a twin extruder temperature 200 ~ 240 ℃ after mixing%.
The method of claim 3, wherein the polymer composite electrode catalyst of the sixth step is bonded to one (+) pole and one (-) pole at 2 mm intervals, and then 10 wt% of citric acid (1000 g) in 10 l of water in a plastic container. ) Was prepared to prepare a citric acid electrolytic solution with a water temperature of 25 ℃, after mounting the combined electrode catalyst applied a voltage of DC12V, the power supply time is 30 ~ 60 minutes, and the (+) and (-) electrodes Electrolysis 30 ~ 60 minutes again to replace the total time is 60 ~ 120 minutes in the polymer composite electrode catalyst for water electrolysis characterized in that the anodic oxidation expansion from the aluminum powder dispersed on the polymer surface to the inside.
A low-resistance Al-CNT polymer composite material using aluminum oxide expansion prepared by the method of claim 1 or 2.
A polymer composite electrode catalyst for water electrolysis prepared by any one of claims 3 to 8.

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