WO2023095960A1 - Ptc constant temperature heating element containing silver particle-graphene composite - Google Patents

Abstract

The present invention relates to a PTC constant temperature heating element and a planar heating element comprising a silver-graphene composite, and a manufacturing method thereof.

Description

PTC constant temperature heating element containing silver particle-graphene composite

The present invention relates to a method for manufacturing a silver particle-graphene composite, a method for manufacturing a high-efficiency PTC constant temperature heating element including a silver-particle graphene composite-based polymer nanocomposite with improved PTC (Positive Temperature Coefficient) strength by adding the same, and a method for manufacturing a high-efficiency PTC constant temperature heating element It relates to a PTC constant temperature heating element and a plane heating element having self-temperature control characteristics manufactured through

Recently, as the research and development of energy-saving heating materials and heating elements using them is accelerated, the development of new technologies for minimizing leakage current due to wet construction has emerged.

Until now, wire heaters have been mainly used as heating elements for heating in a wet construction method. However, since the onboard heating element is made of heating materials such as Ni-Cr and Fe-Ni-Cr, the thermal efficiency is relatively low due to the on-board heating, so the power consumption is relatively high, and one circuit is open due to the series circuit configuration. If it is, there is difficulty in maintenance, such as the entire heating element does not heat up. In addition, there is a high risk of damage to the heating element and fire due to an abnormal heating phenomenon such as local overheating such as collecting heat, and the product lacks stability.

On the other hand, the carbon-based planar heating element has superior thermal efficiency compared to the linear heating element, but since conductive particles such as carbon black are applied as a resistance heating source, this also greatly changes the resistance value due to repeated use and causes abnormalities such as local overheating such as collecting heat. There is a high risk of damage to the heating element and fire due to the heat generation phenomenon, and the product lacks stability.

In order to secure stability, a temperature control system such as an overheating prevention sensor for a linear heating element and a plane heating element is being devised, but it causes abnormal heating phenomena such as local overheating such as collecting heat. The main path of the abnormal heating phenomenon occurs from keeping warm, heat storage, or overheating. In particular, as the temperature of the heat storage part rises rapidly, local overheating of the heating element damages the finishing material and causes an electrical fire.

In particular, when a surface heating element with relatively excellent thermal efficiency is used as a heating element for wet construction, overcoming the problems of the onboard heating element currently being used for wet construction, the leakage current is rapidly increased compared to the onboard heating element, resulting in the operation of the circuit breaker. .

This is because conventional planar heating elements are mostly made of PET film for electrical insulation and flame retardant purposes and have been mainly used for dry construction. In addition, there were weak points such as moisture or condensation due to strong alkalinity in contact with the cement mortar floor during wet construction and interfacial contact with the PET film of the planar heating element having a wider construction floor than the linear heating element.

In addition, as requirements for energy efficiency and stability due to heat generation are expanding, development of a next-generation high-efficiency PTC constant-temperature heating element and a heating element using the same is required.

[Prior art literature]

[Patent Literature]

(Patent Document 1) Republic of Korea Patent Registration No. 10-1168906

(Patent Document 2) Republic of Korea Patent Registration No. 10-1593983

Accordingly, the present invention prepares a silver particle-graphene-based PTC constant-temperature heating paste by mixing a silver particle-graphene composite prepared by a mechanical exfoliation/dispersion method and a polymer binder, and then printing or coating the silver particle-graphene-based polymer It is intended to provide a method for manufacturing a high-efficiency PTC constant temperature heating element using a nanocomposite material, a high-efficiency PTC constant temperature heating element and a plane heating element.

In particular, it is an object of the present invention to provide a high-efficiency PTC constant-temperature heating element and a method for manufacturing the same, which have excellent heat generation characteristics by securing excellent PTC characteristics, reduce power consumption, prevent damage to the heating element due to heat collection, and increase the effect of preventing the risk of fire.

However, the problem to be solved by the present application is not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

One aspect of the present application, a wet treatment step of adding graphite to normal methyl-2-pyrrolidone (N-Methyl-2-pyrolidone, NMP) and stirring;

preparing a graphene-containing composition by mechanically exfoliating and dispersing the wet graphite; and

After adding silver particles to the graphene-containing composition, further mechanically exfoliating and dispersing them to prepare a silver particle-graphene composite,

A method for preparing a silver particle-graphene composite is provided.

Another aspect of the present invention includes preparing a silver particle-graphene composite by the method described above;

mixing the silver particle-graphene composite with a polymer binder to prepare a PTC constant-temperature heating paste based on the silver particle-graphene composite; and

Printing or coating the silver particle-graphene composite-based PTC constant temperature heating paste to prepare a PTC constant temperature heating element using a silver particle-graphene composite-based polymer nanocomposite material; including,

Provided is a method for manufacturing a high-efficiency PTC constant temperature heating element including a silver particle-graphene composite-based polymer nanocomposite material.

Another aspect of the present invention includes a silver particle-graphene composite and a polymer binder,

The PTC intensity (Intensity) calculated by Equation 1 below is 10,000% or more,

A PTC constant temperature heating element is provided.

[Equation 1]

PTC Intensity [%] = (R _100℃ / R _20℃ )x100

(In Equation 1, R _{20 ° C} and R _{100 ° C} are the resistance values (Ω) of the graphene PTC composition measured at 20 ° C and 100 ° C, respectively.)

Another aspect of the present invention is a planar heating layer including a PTC constant temperature heating element including a silver particle-graphene composite and a polymer binder;

insulation layer; and

Including, a foamed adhesive layer between the planar heating layer and the heat insulating layer

A planar heating element is provided.

Another aspect of the present invention, including the planar heating element,

A heating device is provided.

The high-efficiency PTC constant-temperature heating element using the silver-graphene composite-based polymer nanocomposite material according to the present invention secures excellent PTC characteristics and has excellent heating characteristics, while reducing power consumption, preventing damage to the heating element due to heat collection, and significantly reducing the risk of fire. There is an effect that can reduce it.

In addition, due to the excellent properties of the high-efficiency PTC constant temperature heating element using the graphene-based polymer nanocomposite material according to the present invention, it can be used as a flexible planar heating element included in automobile seats in the future, or a nanostructure that requires precise temperature control. It is possible to manufacture a heating device of excellent quality that can be applied in various fields such as a heating device of

1 is a schematic diagram of a planar heating element manufactured by Production Example 3.

2 is a transmission electron microscope (TEM) image of graphene prepared by mechanically exfoliating and dispersing graphite in Preparation Example 1;

3 is a TEM image and an energy dispersive X-ray spectroscopy (EDS) image of the silver nanoparticle-graphene composite prepared in Preparation Example 1.

Figure 4 is a schematic diagram of a planar heating element manufactured by Preparation Example 3 in which a temperature sensor is installed to analyze the heating performance of the planar heating element.

Hereinafter, with reference to the accompanying drawings, embodiments and embodiments of the present application will be described in detail so that those skilled in the art can easily practice the present invention. However, this disclosure may be embodied in many different forms and is not limited to the implementations, examples, and drawings described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted.

Throughout the specification, when a certain component is said to "include", it means that it may further include other components, not excluding other components unless otherwise stated.

One aspect of the present application, a wet treatment step of adding graphite to normal methyl-2-pyrrolidone (N-Methyl-2-pyrolidone, NMP) and stirring; preparing a graphene-containing composition by mechanically exfoliating and dispersing the wet graphite; and adding silver particles to the graphene-containing composition, then mechanically exfoliating and dispersing the silver particles to prepare a silver nanoparticle-graphene composite. .

The graphite is impression graphite, and the average particle size may be 10 μm to 30 μm, and the average particle size of the silver particles may be 1 μm to 5 μm.

The size of the silver particles may become nano-sized while passing through steps of exfoliation and dispersion after being introduced.

Meanwhile, the graphene may be graphene in which two or more layers and 45 or less layers are stacked.

In addition, the wet treatment may be performed for 12 hours or more and 36 hours or less, the temperature of the wet treatment may be 200 ° C. or more and 210 ° C. or less, and the peeling and dispersion may be performed for 5 hours or more and 24 hours or less. can

In one embodiment, the mechanical separation and dispersion may include mechanical separation and dispersion at a speed of 100 to 2,000 rpm using a bead mill, a wet ball mill, a dry stirrer, and a complex stirrer using one or more of them. .

Meanwhile, before and/or after the wet treatment step, a cooling step of cooling the graphite at a temperature of 0 to -100 °C for 20 to 30 hours may be further included.

Through the cooling step, the interlayer/molecular attraction of graphene inside the graphite may be weakened, and as a result, NMP having the closest surface energy to graphite may easily intercalate graphite. NMP intercalated between the graphite layers through such a single or multi-stage thermal shock step further weakens the intermolecular attraction between the graphene layers inside the graphite, so that graphene can be easily prepared through subsequent mechanical exfoliation and dispersion steps.

Another aspect of the present invention includes preparing a silver particle-graphene composite by the method described above; mixing the silver particle-graphene composite with a polymer binder to prepare a PTC constant-temperature heating paste based on the silver particle-graphene composite; and printing or coating a silver particle-graphene composite-based PTC constant-temperature heating paste to prepare a high-efficiency PTC constant-temperature heating element using a silver particle-graphene composite-based polymer nanocomposite; Provides a method for manufacturing a high-efficiency PTC constant temperature heating element including a polymer-based nanocomposite material.

In one aspect of the present invention, the polymer binder is polyethylene, polypropylene, polybutadiene, polyolefin, polyester, polyvinyl chloride, polyvinyl acetate, polyethylene vinyl acetate, polyester-polyethylene vinyl acetate copolymer, polyethylene terephthalate, polystyrene, polyethylene It includes any one selected from the group consisting of ketone, polyethylene terephthalate glycol, polyethyleneimide, and a composite polymer in which one or more of these are mixed, and the silver particle-graphene composite and the polymer binder are in a weight ratio of 1:100 to 40:100. including mixing

Preferably, the polymeric binder may be used by mixing a polyester-based binder and a polyolefin-based binder in a weight ratio of 0.1:10 to 10:0.1, and more preferably, a weight ratio of 1:5 to 5:1. there is.

The polyester binder is a polyester resin having excellent compatibility and adhesiveness with other component layers of a planar heating element such as a polyester plastic film (PET film) or nonwoven fabric, and good chemical resistance, bending resistance and printability (workability). as the main component. More specifically, 5-11 wt% of vinyl-based synthetic resin, 20-35 wt% of polyester-based synthetic resin, 20-50 wt% of aromatic hydrocarbon-based solvent, 20-40 wt% of ketone-based solvent, 0.5-1.5 wt% of antifoaming agent, leveling It can be prepared by mechanically stirring a composition containing 0.5 to 1.5 wt% in a reactor capable of heating. Vinyl-based synthetic resins include polyvinyl chloride and polyvinyl acetate, and polyester-based synthetic resins include polyester and the like. Aromatic hydrocarbon-based solvents include toluene and xylene, and ketone-based solvents include methyl ethyl ketone and acetone. Preferably, the polyester binder includes 5.03wt% of polyvinyl chloride as a vinyl-based synthetic resin, 5.03wt% of polyvinyl acetate, 30.15wt% of polyester as a polyester-based synthetic resin, and an aromatic hydrocarbon solvent. A composition containing 24.12 wt% of toluene, 6.03 wt% of methyl ethyl ketone as a ketone solvent, 28.1 wt% of acetone, 0.5 wt% of an antifoaming agent, and 1 wt% of a leveling agent can be heated. It can be prepared by mechanical stirring in a reactor.

The polyolefin binder is a mixture of crystalline polymers such as polyethylene (PE), polypropylene (PP) and/or ethylene vinyl acetate (EVA), and more specifically, 1 to 10 wt% of polyethylene, A composition containing 1 to 5 wt% of polypropylene, 5 to 30 wt% of polyethylene vinyl acetate copolymer, 10 to 90 wt% of an aromatic hydrocarbon solvent, 0.5 to 1.5 wt% of an antifoaming agent, and 0.5 to 1.5 wt% of a leveling agent is heated. It can be prepared by mechanical stirring in a possible reactor. Preferably, the polyolefin binder contains 2.84 wt% of polyethylene, 0.95 wt% of polypropylene, 9.48 wt% of polyethylene vinyl acetate copolymer, 56.87 wt% of toluene as an aromatic hydrocarbon solvent, 28.44 wt% of xylene, and 0.47 wt% of antifoaming agent. %, it can be prepared by mechanically stirring a composition containing 0.95wt% of a leveling agent in a reactor capable of heating.

More preferably, as the polymeric binder, a mixture of a polyester-based binder and a polyolefin-based binder in a weight ratio of 1:1 may be used.

In one aspect of the present invention, the printing or coating method includes gravure printing, comma coating, silk screen printing, spray coating, dip coating, roll coating, Meyer bar coating, blade coating, microgravure coating, slot die coating, slide coating, curtain It includes any one method selected from the group consisting of coating and printing or coating methods in which one or more of these are mixed.

Another aspect of the present invention provides a PTC constant-temperature heating element including a silver particle-graphene composite and a polymer binder and having a PTC intensity of 10,000% or more as calculated by Equation 1 below.

[Equation 1]

PTC Intensity [%] = (R _100℃ / R _20℃ )x100

(In Equation 1, R _{20 ° C} and R _{100 ° C} are the resistance values (Ω) of the graphene PTC composition measured at 20 ° C and 100 ° C, respectively.)

Another aspect of the present invention is a planar heating layer including a PTC constant temperature heating element including a silver particle-graphene composite and a polymer binder; insulation layer; It provides a planar heating element comprising a; and a foamed adhesive layer between the planar heating layer and the heat insulating layer.

Meanwhile, the foamed adhesive layer may be a foamed polyurethane layer containing silica airgel powder.

The polyurethane layer may include 1 wt% or more and 5 wt% or less of silica airgel powder.

The silica airgel powder has a particle size of 2-40 μm, a pore diameter of 20 nm or less, a particle density of 120-150 kg/m ³ , a surface area of 600-800 m ² /g, and a thermal conductivity of 0.012 W/m K. @ 25°C or less.

In addition, the heat insulating layer may be a polymer foam heat insulating sheet layer or a silica airgel heat insulating sheet layer composed of closed cells.

The thermal conductivity of the polymer foam insulation sheet composed of the closed cell may be 0.05 W/m K or more and 0.07 W/m K or less, and the thermal conductivity of the silica airgel insulation sheet may be 0.02 W/m K or more and 0.04 W/m Can be less than or equal to K.

The thermal conductivity of the planar heating element is 0.07 W / m K or less, the leakage current is 0.3 mA or less, and the power consumption reduction rate at a heating temperature of 40 ° C. compared to the power consumption at ambient temperature may be 40% or more.

That is, the foamed adhesive layer and the heat insulating layer of the planar heating element can improve the heating efficiency by reducing the thermal conductivity, leakage current and power consumption of the planar heating element.

The planar heating element may further add a configuration commonly used in a planar heating element. More specifically, there may be an electrode layer, an electrically conductive layer, a waterproof film layer, other heating layers, a metal or non-metal film layer, a non-woven fabric layer, and the like, but the present invention is not limited thereto.

The electrode layers are formed with a certain width on both sides of the PTC constant temperature heating element to control the flow of current between the electrodes and maintain the heating temperature of the heating element. Materials of the electrodes of the electrode layer include conductive polymers such as polyaniline, polypyrrole, and polythiophene; conductive components such as carbon; At least one selected from the group consisting of metals such as silver, gold, platinum, palladium, copper, aluminum, tin, iron and nickel may be used. Preferably, copper having excellent thermal conductivity and electrical conductivity is used.

Other heating layers may be stacked together with a PTC constant temperature heating element on top of the electrode layer, and generate heat when electricity flows. The material is preferably any one or a mixture of two or more of conductive carbon, carbon black, graphene, carbon nanotube (CNT), and graphite, and a heating layer woven of carbon fiber, CNT or graphene on nonwoven fabric. An impregnated heating layer, a nonwoven fabric impregnated with conductive carbon, a heating layer prepared by coating CNT, graphene paste, or ink on a base film may be further included and used.

As the other film layer, one or more layers selected from metal, non-metal, or metal-non-metal mixture films may be additionally attached. An air layer may be formed in the metal, non-metal or metal-non-metal mixed film. Aluminum, copper, etc. may be included as the metal film, polymer or ceramic may be selectively used as the non-metal film, and aluminum-polymer or aluminum-ceramic may be selectively used as the metal-nonmetal mixed film. Specifically, the polymer film is polyethylene terephthalate, and the metal-non-metal mixed film is preferably aluminum-polyethylene terephthalate, but is not limited thereto. The metal, non-metal, or metal-non-metal mixed film may be attached to one or both surfaces of the outermost surface of the heating element, but is not limited thereto and may be added in one or more layers between various layers of the heating element.

In addition, in order to minimize the leakage current due to the increase in the large area during construction of the heating element, a waterproof film layer and a nonwoven fabric layer interposed between the heating element and the waterproof film layer may be further included on both sides of the heating element.

The waterproof film layer is used for the purpose of minimizing the leakage current generated according to the increase in the large area during wet construction and providing waterproofness during wet construction. Any material capable of imparting insulation and waterproofness may be used without limitation, and specifically, polyethylene terephthalate, polypropylene, polyester, polystyrene, polyether ether ketone, polyethylene terephthalate glycol, and polyethyleneimide. One selected from the group consisting of can be used.

The non-woven fabric layer is formed of fibers, and a plurality of pores formed between the fibers and irregularities may be further formed on the surface. Leakage current can be prevented through air pockets caused by pores and irregularities of the nonwoven fabric. The fibers forming the nonwoven substrate may have an average diameter of 0.1 μm to 10 μm. Fibers include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as aramids, polyacetals, polycarbonates, polyimides, polyether ether ketones, polyether sulfones, and polyethers. It may be formed of phenylene oxide, polyphenylene sulfide, polyethylene naphthalene, etc., but is not limited thereto.

Each structure layer is T-die method, inflation method, extrusion lamination, co-extrusion lamination; It can be laminated using an adhesive method such as dry lamination, sandwich lamination or thermal lamination using an adhesive such as polyurethane, unsaturated polyester, or epoxy resin, and more preferably dry lamination using a polyurethane adhesive and an isocyanate curing agent. can

Another aspect of the present invention provides a heating device including the planar heating element.

Hereinafter, the present application will be described in more detail using examples, but the present application is not limited thereto.

[Preparation Example 1] Preparation of graphene and silver particle-graphene composite

100 g of impression graphite (d50: 20 μm, carbon content: minimum 99.5%) was added to 1,000 g of NMP (N-Methyl-2-pyrrolidone, boiling point (bp): 204 ° C) and mechanically stirred for 24 hours. while wet.

The processed impression graphite is a counter rotating bead mill equipped with a disk coupled to a zirconia ceramic bead and a rotating shaft, processing capacity: maximum 1.8L / bead: zirconia (ZrO ₂ ), φ 0.8mm, A graphene composition was prepared by mechanical exfoliation and dispersion for 12 hours with centrifugal force by rotation of the disk (Mixer 100-200 rpm / Agitator 1,000-2,000 rpm) at a filling amount of 950 g).

3 g of silver particles (spherical, d50: 2.6 μm) were added to the prepared graphene composition, and the disk was rotated in a counter rotating bead mill equipped with a disk coupled to a zirconia ceramic bead and a rotating shaft. A silver particle-graphene composite coated with silver nanoparticles on the graphene surface was prepared by mechanical exfoliation and dispersion for 12 hours by centrifugal force by (Mixer 100-200 rpm / Agitator 1,000-2,000 rpm). .

[Example]

As shown in Table 1 below, 25 wt% of polyester as a polyester binder in 12 wt% of the silver particle-graphene composite prepared in Preparation Example 1, a polyolefin binder (polyethylene vinyl acetate copolymer, polyethylene vinylacetate copolymer ) at 25 wt%, solvent (using a mixture of toluene and xylene) at 45 wt%, Fatty acid modified polyester was added as a dispersant in an amount of 1 phr (parts per hundred rubber) compared to the total polymer binder content, and additional dispersion and exfoliation were performed in a counter rotating bead mill for 1 hour.

Then, 3.5 phr of Toluene Diisocyanate (TDI) was added as a curing agent and 3.5 phr of Dicumyl Peroxide (DCP) as a crosslinking agent to prepare a PTC ink (paste) based on a silver particle-graphene composite. . The contents of the components are shown in Table 1 below.

Ingredients	Composition [wt%]	additive
Silver particle-graphene composite	5	* Dispersant 1phr (added when mixing components) * Curing agent 3.5 phr (added after mixing the components) * Cross-linking agent 3.5 phr (added after mixing the components)
polyester binder	25
Polyolefin Binder	25
solvent	45
Sum	100

The prepared silver particle-graphene composite-based PTC ink (paste) was applied to a substrate and treated at 130 ° C. for 15 minutes to silk-screen print to prepare a graphene-based PTC heating element (coating film) having a thickness of 1 μm.

[Comparative example]

In the embodiment, instead of 5 wt% of the silver particle-graphene composite, 9 wt% of acetylene carbon black and 3 wt% of carbon nanotube (CNT) were changed, and the content of the binder, solvent, and additive was adjusted to obtain carbon black/CNT-based PTC ink (paste ) was prepared. The contents of the components are shown in Table 2 below.

Ingredients	Composition [wt%]	additive
acetylene carbon black	9	* Dispersant 1phr (added when mixing components) * Curing agent 5 phr (added after mixing the components) * Cross-linking agent 2phr (added after mixing the components)
carbon nanotube	3
polyester binder	22
Polyolefin Binder	22
solvent	44
Sum	100

[Production Example 2] Manufacturing constant temperature heating element

The PTC inks (paste) of Examples and Comparative Examples were applied to a substrate and treated at 130 ° C. for 15 minutes, and silk screen printing was performed to prepare a PTC constant temperature heating element (coating film) having a thickness of 1 μm.

[Production Example 3] Production of planar heating element

After spray-coating the foamed adhesive material on one side of the silver particle-graphene composite-based PTC constant temperature heating element prepared in Preparation Example 2 using the silver particle-graphene composite-based PTC ink (paste) of Example, the heat insulating material After bonding (laminating) by thermal compression (80 ~ 120 ℃ / 6 kgf / cm ² ), heat treatment at a temperature of 40 ~ 50 ℃ for 24 hours to foam and harden the adhesive material, Planar heating element of the structure shown in Figure 1 was manufactured.

For the foamed adhesive material, 21 wt% of liquid polyurethane, 59 wt% of methyl propyl ketone (MPK), 1 wt% of silica airgel powder, and 1.5 phr of a dispersant were added/mixed, followed by vigorous stirring for 30 minutes, and liquid polyisocyanate It was prepared by adding/mixing 15 wt% and further stirring for 10 minutes. Thereafter, 4 wt% of water as a foaming agent was prepared by adding/mixing and stirring immediately before spray coating.

Components and content ranges of the foamed adhesive material are shown in Table 3 below.

Ingredients		Composition [wt%]	note
subject	Polyurethane	20 to 25	* Dispersant 1.5phr
curing agent	polyisocyanate	10 to 15
organic solvent	MPK	55 to 60
blowing agent		water		1 to 5
additive		silica airgel		1 to 5
Sum		100

The silica airgel powder has a particle size of 2-40 μm, a pore diameter of 20 nm or less, a particle density of 120-150 kg/m ³ , a surface area of 600-800 m ² /g, and a thermal conductivity of 0.012 W/m K. @ 25 ℃ or less.

In addition, as the heat insulating material, a polymer foam insulating sheet composed of closed cells (thermal conductivity: 0.05 to 0.07 W/m K) or a silica airgel insulating sheet (thermal conductivity: 0.02 to 0.04 W/m K) was used

[Experimental Example 1] Transmission electron microscope (TEM) and EDS analysis of graphene and silver particle-graphene composite of Preparation Example 1

A TEM image of graphene prepared by mechanically exfoliating and dispersing graphite in Preparation Example 1 is shown in FIG. 2 .

Through TEM, graphene was confirmed to have 2 to 23 layers.

In addition, it was confirmed through EDS analysis that it contained carbon and oxygen elements, and the content of carbon was 98.99 atomic % (atom %) and the oxygen content was confirmed to be 1.01 atomic % (atom %).

Meanwhile, a TEM image of the silver nanoparticle-graphene composite prepared in Preparation Example 1 is shown in FIG. 3A.

Through the additional mechanical exfoliation and dispersion process, it was confirmed that the graphene layer was reduced to have 2 to 15 layers, and silver nanoparticles were attached to the graphene surface.

In addition, as shown in FIG. 3B, it was confirmed through EDS analysis that the silver nanoparticle-graphene composite contained carbon, oxygen, and silver, and the carbon content was 84.6 atom%, and the oxygen content It was confirmed that the silver content was 14.6 atomic% (atom%) and the silver content was 0.8 atomic% (atom%).

[Experimental Example 2] Powder resistance analysis of the silver nanoparticle-graphene composite prepared in Preparation Example 1

Powder resistance of the silver nanoparticle-graphene composite prepared in Preparation Example 1 was measured, and the resultant values are shown in Table 4 below.

Powder resistance was measured using a powder resistance meter (Hantech, HPRM-FA). The thickness and density of a powder as a unit of measurement pressure changes. Resistance, sheet resistance, specific resistance and electrical conductivity were measured.

LOAD [kgf]	thickness [mm]	resistance (R) [Ω]	noodle resistance (SR) [Ω/sq]	resistivity (VR) [Ωcm]	electrical conductivity (Conductivity) [S/cm]	density (Density) [g/cc]
486.50	1.932	0.00363	0.016	0.003	315.012	1.362
1027.50	1.691	0.00319	0.014	0.002	408.920	1.556
1514.00	1.545	0.00297	0.013	0.002	481.049	1.703

As the thickness became thinner, it was confirmed that the density decreased and the resistance decreased (electrical conductivity improved).

[Experimental Example 3] PTC intensity analysis of PTC constant temperature heating element

Using the PTC ink (paste) of Examples and Comparative Examples, electrodes are installed on the PTC constant-temperature heating element manufactured according to Preparation Example 2, and wires connected to the electrodes are pulled out to the outside of the oven, and the digital multimeter instrument placed outside the oven connected.

Thereafter, while increasing the oven temperature by 10 ° C from 20 to 100 ° C, the resistance change of the PTC constant temperature heating element was measured using a digital multimeter device to measure the PTC intensity and shown in Table 5 below.

temperature [℃]	Example PTC ink (paste) use PTC constant temperature heating element	Comparative Example Using PTC Ink (Paste) PTC constant temperature heating element
PTC Intensity [%]	11,000%	781%
☞ PTC Intensity [%] = (R 100℃ / R 20℃ )x100

In Table 5, R _{20 ° C} and R _{100 ° C} are resistance values (Ω) measured at 20 ° C and 100 ° C, respectively.

It was found that the silver particle-graphene-based PTC constant temperature heating element of Example exhibited superior PTC characteristics compared to the existing PTC constant temperature heating element of Comparative Example.

[Experimental Example 4] Analysis of thermal conductivity and leakage current of plane heating element

The thermal conductivity and leakage current of the PTC constant-temperature heating element prepared using the PTC ink (paste) of Example and the planar heating element prepared by Preparation Example 3 are analyzed and shown in Table 6 below.

Thermal conductivity was measured using a thermal conductivity meter (model name : TCI-2-A).

In addition, the leakage current is measured by spraying 20g of water on the lower iron plate among the two iron plates, installing the PTC constant temperature heating element and plane heating element on the lower iron plate, and spraying 20g of water on the upper surface of the PTC constant temperature heating element and plane heating element, then on the PTC constant temperature heating element and plane heating element. After placing another iron plate on the , leakage current was measured using a leakage current meter (MI 2094 (METREL)).

	thermal conductivity [W/m K]	leakage current [mA]
PTC constant temperature heating element prepared according to Preparation Example 2 using the PTC ink (paste) of Example	0.1	0.5
Planar heating element of Production Example 3	0.05	0.2

The planar heating element of Preparation Example 3 in which a heat insulating material is bonded to one side of the PTC constant temperature heating element manufactured according to Preparation Example 2 using the PTC ink (paste) of Example 3 using the PTC ink (paste) of Example Compared to the PTC constant temperature heating element manufactured according to Preparation Example 2, it was confirmed that the thermal conductivity was lowered and the leakage current was reduced.

That is, compared to the PTC constant-temperature heating element prepared according to Preparation Example 2 using the PTC ink (paste) of Example 3, the plane heating element of Preparation Example 3 had reduced heat loss and leakage current, and improved heating efficiency.

[Experimental Example 5] Analysis of the heating performance of the plane heating element

As shown in Figure 4, four temperature sensors were installed on one side of the planar heating element manufactured by Preparation Example 3.

After connecting to a power source, the heating temperature was adjusted to 40° C. over 1 hour, and power energy, voltage, and current were measured, and are shown in Table 7 below.

hour [minute]	power energy [W]	Voltage [V]	electric current [A]	fever temperature [℃]				around temperature [℃]
				①	②	③	④
0	14.4	12	1.2	25.4	25.2	25.2	25.3	23.1
60	8.4	12	0.7	40.3	39.6	39.4	39.7	22.7

The exothermic temperature in Table 7 is the temperature measured by each of the four installed sensors.

Through the heating performance analysis, it was found that the plane heating element manufactured by Preparation Example 3 had a power consumption reduction rate of 41.7% at a heating temperature of 40 ° C. compared to power consumption at ambient temperature.

In this way, when the PTC constant temperature heating element and the surface heating element using the PTC ink (paste) of the embodiment of the present invention are energized under conditions where the temperature rises, the electrical resistance increases and the amount of current decreases, thereby effectively reducing the amount of heat generated. Through the self-temperature control (or constant temperature heating) characteristics of these PTC constant temperature heating elements and flat heating elements, it is possible to prevent damage to heating elements or fire hazards due to overheating and overcurrent, and to reduce power consumption. A heating element can be manufactured.

As described above, the PTC constant temperature heating element of the present invention includes a silver particle-graphene composite, so that the PTC effect is improved compared to the conventional PTC constant temperature heating element using carbon black, CNT or graphite. It can be efficiently manufactured, and due to these excellent characteristics, it is expected to be used as a heating device such as a heating sheet and a nano heating element requiring temperature control in the future, and can be applied to various other fields.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the scope of the present invention is not limited to the disclosed embodiments, and is interpreted by the claims to be described later, and all changes or modified forms of technical ideas derived from the meaning and scope of the claims and equivalent concepts thereof It should be construed as being included in the scope of the present invention.

The high-efficiency PTC constant-temperature heating element using the silver-graphene composite-based polymer nanocomposite material according to the present invention secures excellent PTC characteristics and has excellent heating characteristics, while reducing power consumption, preventing damage to the heating element due to heat collection, and significantly reducing the risk of fire. There is an effect that can reduce it.

In addition, due to the excellent properties of the high-efficiency PTC constant temperature heating element using the graphene-based polymer nanocomposite material according to the present invention, it can be used as a flexible planar heating element included in automobile seats in the future, or a nanostructure that requires precise temperature control. It is possible to manufacture a heating device of excellent quality that can be applied in various fields such as a heating device of

Claims (11)

1. A wet treatment step of adding graphite to normal methyl-2-pyrrolidone (N-Methyl-2-pyrolidone, NMP) and stirring;

   preparing a graphene-containing composition by mechanically exfoliating and dispersing the wet graphite; and

   After adding silver particles to the graphene-containing composition, further mechanically exfoliating and dispersing them to prepare a silver particle-graphene composite,

   A method for producing a silver particle-graphene composite.
2. According to claim 1,

   The mechanical separation and dispersion comprises mechanical separation and dispersion at a speed of 100 to 2,000 rpm using a bead mill, a wet ball mill, a dry stirrer, and a composite stirrer using one or more of them,

   A method for producing a silver particle-graphene composite.
3. preparing a silver particle-graphene composite by the method of claim 1 or 2;

   mixing the silver particle-graphene composite with a polymer binder to prepare a PTC constant-temperature heating paste based on the silver particle-graphene composite; and

   Printing or coating the silver particle-graphene composite-based PTC constant temperature heating paste to prepare a PTC constant temperature heating element using a silver particle-graphene composite-based polymer nanocomposite material; including,

   Method for manufacturing a PTC constant temperature heating element including a silver particle-graphene composite-based polymer nanocomposite material.
4. According to claim 3,

   The polymer binder is polyester, polyethylene vinyl acetate, polyester-polyethylene vinyl acetate copolymer, polyvinyl chloride, polyethylene, polypropylene, polybutadiene, polyolefin, polyvinyl chloride, polyvinyl acetate, polyethylene terephthalate, polystyrene, polyethylene ketone , Polyethylene terephthalate glycol, polyethyleneimide, and any one selected from the group consisting of a composite polymer in which one or more of them are mixed,

   Including a silver particle-graphene composite, wherein the silver particle-graphene composite and the polymer binder are mixed in a weight ratio of 1:100 to 40:100.

   Manufacturing method of PTC constant temperature heating element.
5. According to claim 4,

   The printing or coating method includes gravure printing, comma coating, silk screen printing, spray coating, dip coating, roll coating, Mayer bar coating, blade coating, microgravure coating, slot die coating, slide coating, curtain coating, and one or more of these Including a PTC constant temperature heating element including a silver particle-graphene composite, including any one method selected from the group consisting of mixed printing or coating methods,

   Manufacturing method of PTC constant temperature heating element.
6. A silver particle-graphene composite and a polymer binder,

   The PTC intensity (Intensity) calculated by Equation 1 below is 10,000% or more,

   PTC constant temperature heating element.

   [Equation 1]

   PTC Intensity [%] = (R _100℃ / R _20℃ )x100

   (In Equation 1, R _{20 ° C} and R _{100 ° C} are the resistance values (Ω) of the graphene PTC composition measured at 20 ° C and 100 ° C, respectively.)
7. a planar heating layer including a PTC constant temperature heating element including a silver particle-graphene composite and a polymer binder;

   insulation layer; and

   Including, a foamed adhesive layer between the planar heating layer and the heat insulating layer

   face heating element.
8. According to claim 7,

   The foamed adhesive layer is a foamed polyurethane layer containing silica airgel powder,

   face heating element.
9. According to claim 7,

   The heat insulating layer is a polymer foam heat insulating sheet layer or a silica airgel heat insulating sheet layer composed of closed cells,

   Face heating element.
10. According to claim 7,

    The thermal conductivity of the planar heating element is 0.07 W / m K or less,

    Leakage current is less than 0.3 mA,

    Face heating element.
11. Including the planar heating element of claim 7,

    heating device.

Images