KR20220169865A - Flexible Planar Heater and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a flexible planar heating element and a method of manufacturing the same. The flexible planar heating element is made of nanocarbon composite material containing polymer, nanocarbon filler, hardener, and catalyst. The polymer is epoxy, a thermosetting resin. The nanocarbon filler includes multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). The flexible planar heating element is in the form of a film, and at least one of the multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) is surface-modified with a pyrene copolymer. According to the present invention, since the pyrene copolymer is non-covalently bonded to the surface of the CNT and GNP, and the surface is modified, it is possible to suppress agglomeration between particles and improve the dispersibility thereof. Also, the same can be effectively mixed with second conductive particles. The same has excellent high-temperature heating characteristics at low voltage. In addition, rapid high-output heat generation and excellent high-temperature stability are also secured. Thus, it is possible to achieve excellent durability.

Description

Flexible Planar Heater and Manufacturing Method Thereof

The present invention relates to a flexible planar heating element and a manufacturing method thereof, and more particularly, to a flexible planar heating element imparted flexibility by applying a bitrimer epoxy and a manufacturing method thereof.

In general, a heating material that can be applied as a heater for a battery needs to secure low-voltage drive, high-temperature heating characteristics, rapid high-power heating performance, flexibility, etc., but it is very difficult to achieve the above-described characteristics with existing heating materials.

In addition, since it must operate at a high temperature of 250 ° C, high temperature stability is required, and durability must be guaranteed even under severe conditions of 85 ° C / 85 RH%.

To this end, it can be said that it is appropriate to fill a heat-generating material such as nano-carbon or metal in a cross-linked thermosetting resin such as epoxy, and research and development are being conducted. It has disadvantages that are difficult to apply to

Accordingly, a heating material for application as a heater for a battery and a technology for incorporating it into a planar heating element must select a polymer material with good flexibility and high heat resistance, and effectively disperse the nano-carbon filler to generate heat uniformly over the entire surface. need.

Republic of Korea Patent Registration No. 10-2205081 Republic of Korea Patent Registration No. 10-2073670

The present invention has been devised in view of and solving the above-described conventional problems, and an object of the present invention is to provide a flexible planar heating element and a method for manufacturing the same, in which flexibility is imparted by applying a vitrimer epoxy.

The present invention is a surface-modified carbon nano tube (hereinafter referred to as 'CNT') and graphene nano platelet (hereinafter referred to as 'GNP') to ensure excellent dispersibility. An object of the present invention is to provide a flexible planar heating element and a manufacturing method thereof capable of realizing excellent durability by suppressing aggregation between particles to have excellent high-temperature heating characteristics at low voltage as well as rapid high-output heating and excellent high-temperature stability.

In the present invention, CNT and GNP are evenly dispersed, adhesive strength is strong, and a flexible epoxy resin is used instead of a brittle conventional epoxy resin. The purpose is to provide a flexible planar heating element and a method for manufacturing the same, which can maximize and exhibit planar heating characteristics through high electrical conductivity.

An object of the present invention is to provide a flexible planar heating element exhibiting suitable characteristics as a battery heater and a method for manufacturing the same.

The flexible surface heating element according to the present invention for achieving the above object is made of a nano-carbon composite material including a polymer, a nano-carbon filler, a curing agent, and a catalyst; The polymer is an epoxy, which is a thermosetting resin, and the nano-carbon filler includes multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs).

Here, the flexible plane heating element may be made in the form of a film.

Here, the flexible plane heating element may be used as a battery heater.

In addition, the method for producing a flexible surface heating element according to the present invention for achieving the above object, (A) synthesizing a pyrene copolymer having a pyrene functional group; (B) providing multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), and mixing the pyrene copolymer with at least one or both of them to perform a surface modification treatment; (C) preparing a nano-carbon filler by mixing an organic solvent with multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), at least one or both of which are surface-modified; (D) preparing a nano-carbon composite material by mixing a thermosetting resin, a curing agent and a catalyst with a nano-carbon filler; (E) coating the nano-carbon composite material on a support to form a planar heating element in the form of a film; characterized in that it comprises a.

Here, (F) forming electrodes on both ends of the planar heating element in the form of a film; may further include.

In addition to describing more various embodiments of the flexible surface heating element and its manufacturing method according to the present invention for achieving the above object, it will be described in detail below.

According to the present invention, it is possible to provide a flexible planar heating element securing excellent flexibility by applying a bitrimer epoxy.

According to the present invention, since the pyrene copolymer is non-covalently bonded to the surfaces of CNT and GNP to modify the surface, aggregation between particles can be suppressed and their dispersibility improved, and they can be effectively mixed with second conductive particles. In addition, it is possible to provide a flexible planar heating element capable of realizing excellent durability by securing rapid high-output heating and excellent high-temperature stability as well as excellent high-temperature heating characteristics at low voltage.

According to the present invention, since CNTs and GNPs are evenly dispersed, adhesive strength is strong, and a flexible epoxy resin is grafted, rather than a common epoxy resin that is brittle, it has a flexible surface that can secure excellent flexibility even when a large amount of nano-carbon is included. A heating element may be provided.

According to the present invention, it is possible to implement constant heat generation over the entire surface, and it is possible to provide a flexible surface heating element that exhibits effective functions and characteristics as a battery heater.

1 is a chemical structural formula showing a pyrene copolymer used as a surface modifier in the present invention.
Figure 2 is an exemplary view showing a flexible surface heating element according to an embodiment of the present invention.
3 is a process flow chart showing a method for manufacturing a flexible planar heating element according to an embodiment of the present invention.
Figure 4 is characteristic evaluation data showing the tensile strength (tensile strength) according to the content of CNT and GNP in the flexible planar heating element according to the present invention.
Figure 5 is characteristic evaluation data showing the stress-strain according to the content of CNT and GNP in the flexible planar heating element according to the present invention.
6 to 8 are characteristic evaluation data showing the time-heating temperature according to the voltage in the flexible planar heating element according to the present invention,
9 is characteristic evaluation data showing electrical conductivity measurement values in a flexible planar heating element according to the present invention.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings, and through this detailed description, the purpose and configuration of the present invention and the characteristics thereof will be better understood.

Flexible surface heating element according to an embodiment of the present invention is composed of a configuration including a nano-carbon composite material consisting of a polymer, a nano-carbon filler, a curing agent, a catalyst.

In addition to this, an organic solvent may be included for effective dispersion treatment of the materials used.

As shown in FIG. 2, the flexible surface heating element may be formed by being coated on a support.

The flexible surface heating element is formed in the form of a film by coating as described above, and the support may be removed.

It is preferable to use a film made of polyimide (PI) or Teflon as the support.

It can be said that it is more preferable to apply a polyimide film having excellent heat resistance in addition to the ease of separation from the flexible planar heating element made in the form of a film by coating as the support.

Electrodes may be formed at both ends of the flexible planar heating element. The electrode is formed to apply a voltage to the flexible plane heating element and may be formed of a (+) electrode and a (-) electrode.

At this time, the electrode is a silver (Ag) nanowire or silver (Ag) paste, an oxide electrode such as ITO (indium tin oxide), ZnO (zinc oxide), SnO ₂ (tin oxide), carbon nanotubes, such as graphene It may be formed of any one selected from non-oxide electrodes, and various other electrode materials having conductivity may be applied without being particularly limited thereto.

As the polymer, epoxy, which is a thermosetting resin, is used.

At this time, the epoxy is preferably a bisphenol type epoxy, and more preferably, a dylpether of bisphenol A (DGEBA) epoxy is used.

The curing agent may be one selected from fatty acid, succinic anhydride, glutaric anhydride, and a carboxylic acid-based cured product.

The catalyst uses zinc acetate dihydrate or imidazole-based amine.

Here, the curing agent and catalyst are used to impart flexibility.

The organic solvent is used to disperse conductive particles such as nanocarbon, and chloroform, acetone, toluene, methylpyrrolidone (NMP), isopropyl alcohol (IPA), tetrahydrofuran (THF), dimethylformamide ( DMF), at least one of which may be selected and used.

The nano-carbon filler may use carbon nanotubes (CNT) and graphene (GNP), and in detail, it is more preferable to use a combination of multi-walled carbon nanotubes (CNT) and graphene nanoplatelets (GNP). can do.

At this time, it is preferable to mix and use the multi-walled carbon nanotubes (CNTs) and the graphene nanoplatelets (GNPs) in a weight ratio of 7 to 9:1 to 3.

More specifically, the multi-walled carbon nanotubes (CNTs) have a length of 100 to 200 μm and a diameter of 6 to 15 nm, and the graphene nanoplatelets (GNPs) have a diameter of 20 to 30 μm and a surface area of 6 to 15 nm. It is preferable to apply that of 30 to 60 m ² /g.

Here, the epoxy and the curing agent are blended in an equivalent ratio of 1:0.5 to 1.5, and the catalyst is preferably blended in an amount of 1 to 3 parts by weight based on 100 parts by weight of the epoxy.

In addition, the nano-carbon filler is preferably formulated to account for 8 to 15% by weight of the total 100% by weight of the nano-carbon composite material.

In the present invention, by increasing the heat resistance of the mixed binder through such components and formulations, it is possible to provide an advantage that there is no change in resistance of the material or damage to the coating film even when heat is generated at a high temperature of 200 ° C. or higher.

Here, at least one or both of the multi-walled carbon nanotubes (CNTs) and the graphene nanoplatelets (GNPs) are preferably surface-modified with a surface modifier made of a pyrene copolymer.

As shown in FIG. 1, the surface modifier made of the pyrene copolymer may have a structure represented by Chemical Formula 1 below.

(Formula 1)

Here, in the pyrene copolymer, group A, group B, and group C are bonded to each other as a block copolymer, and pyrene is bonded to group B to form a network.

In this case, the pyrene copolymer is preferably synthesized in a ratio of (x+y) : z = 7 to 9 : 1 to 3, and x may have a composition smaller than or equal to y.

Here, the pyrene copolymer having the structure of Chemical Formula 1 preferably has a molecular weight of 10,000 to 40,000 g/mol.

Here, in the surface modification treatment, it is preferable to graft the pyrene copolymer and the multi-walled carbon nanotube (CNT) or graphene nanoplatelet (GNP) at a weight ratio of 1 to 3: 1 for surface modification treatment. .

Here, when the blending ratio is less than 1:1, the surface modification effect is low and dispersibility is lacking, resulting in poor properties and performance. can be lowered

In this way, by utilizing the surface modification using the pyrene copolymer, it is possible to induce high electrical conductivity while maximizing the dispersion of the nano-carbon filler in which the CNT and GNP are blended, and through this, the surface heating characteristics can be improved.

As an example, the flexible planar heating element according to the present invention having a configuration including the nano-carbon composite material as described above has excellent high-temperature heating characteristics at low voltage, as well as rapid high-output heating and excellent high-temperature stability, so that excellent durability can be implemented. Can be used as a battery heater.

Meanwhile, hereinafter, a method for manufacturing a flexible planar heating element according to an embodiment of the present invention will be described.

As shown in Figure 3, the flexible planar heating element manufacturing method according to an embodiment of the present invention, pyrene copolymer synthesis step (S100), CNT / GMP surface modification step (S200), nano-carbon filler manufacturing step (S300), nano It may be configured to include a carbon composite material manufacturing step (S400), a coating step (S500), and an electrode forming step (S600).

In addition, a support removal step (S700) of removing the support used as the substrate in the coating step (S500) may be included.

The pyrene copolymer synthesizing step (S100) is a step of synthesizing a pyrene copolymer having a pyrene functional group.

The pyrene copolymer synthesis step (S100) is largely a step of synthesizing a polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA), and a polymethyl methacrylate into which a pyrene functional group is introduced. It can be carried out in the step of synthesizing methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA).

In detail, the step of synthesizing the polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) may be sequentially performed through the steps presented below.

(1) After putting chain transfer agent (CTA) and 2,2'-azobis (2-methyl-propionitrile (AINB) in a flask, stirring under vacuum to remove moisture and foreign substances on the surface, and then adding an organic solvent, Stir again at 250 to 350 rpm to completely dissolve.

(2) After adding and stirring dimethylaminoethyl methacrylate (DMAEMA) while flowing argon (Ar) gas, it is put into an oil bath at 70 to 90° C. and reacted for 12 to 15 hours.

(3) After adding methyl methacrylate (MMA) while flowing argon (Ar) gas, the reaction is further proceeded for 2 to 3 days.

(4) After the reaction is finished, put in an ice bath to stop the reaction, dilute the reactant in an organic solvent, and precipitate in n-hexane to obtain a precipitate.

Here, after obtaining the precipitate, in order to remove monomers and impurities that did not participate in the reaction in the precipitate, the precipitate was again diluted with an organic solvent and then precipitated in n-hexane to obtain a precipitate again. You can proceed, and you can repeat this 3 times.

(5) The precipitate is vacuum dried at room temperature for 1 to 3 days.

In the step of synthesizing polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) by sequentially performing these processes, the dimethylaminoethyl methacrylate (DMAEMA) and the The molecular weight of the synthesized polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) can be controlled by adjusting the amount of methyl methacrylate (MMA) added.

In addition, the step of synthesizing the pyrene functional group-introduced polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) can be sequentially performed through the steps presented below.

(1) Put polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) in a flask, add dimethylformamide (DMF) solvent, stir to completely dissolve.

(2) After adding 1-(bromomethyl)pyrene, react at room temperature for 20 to 30 hours to obtain a reactant.

(3) Remove the dimethylformamide (DMF) solvent from the reactants, add an organic solvent to dissolve them, and put them in hexane to obtain a precipitate.

(4) The precipitate is subjected to vacuum drying at room temperature for 1 to 3 days.

That is, a pyrene copolymer for use as a surface modifier may be synthesized through the above-described process, and the pyrene copolymer may be synthesized to have a molecular weight in the range of 10,000 to 40,000 g/mol.

In other words, the pyrene copolymer can be synthesized to have a chemical structure as shown in FIG. 1 .

Here, in the pyrene copolymer, as shown in FIG. 1, as a block copolymer, group A, group B, and group C are bonded to each other, and pyrene is bonded on group B to form a network. have

In this case, the pyrene copolymer is preferably synthesized in a ratio of (x+y) : z = 7 to 9 : 1 to 3, and x may have a composition smaller than or equal to y.

The CNT/GMP surface modification step (S200) includes multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), and at least one or both of them are mixed with the pyrene copolymer to surface This is a modification step.

In detail, the CNT / GMP surface modification step (S200) may sequentially proceed with the process presented below.

(a) Multi-walled carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs) and an organic solvent are put into a vial and mixed to form a dispersion, followed by primary ultrasonic treatment for 10 to 30 minutes.

The multi-walled carbon nanotubes (CNTs) may have a length of 100 to 200 μm and a diameter of 6 to 15 nm, and the graphene nanoplatelets (GNPs) may have a diameter of 20 to 30 μm and a surface area of 30 to 15 nm. 60 m ² /g can be used.

(b) After dissolving the pyrene copolymer in an organic solvent, it is mixed with the multi-walled carbon nanotube (CNT) dispersion or graphene nanoplatelet (GNP) dispersion that has been subjected to primary ultrasonic treatment and secondary ultrasonic treatment for 10 to 30 minutes. do.

(c) The multi-walled carbon nanotube (CNT) mixture or graphene nanoplatelet (GNP) mixture in which the pyrene copolymer is mixed is stirred at 250 to 350 rpm for 20 to 30 hours.

(d) By removing the unreacted pyrene copolymer through a filter, the pyrene copolymer is coated to obtain surface-modified multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs).

At this time, the process of (d) may be repeated three times.

As the filter, a micro Teflon filter or the like can be used.

The nano-carbon filler manufacturing step (S300) is a multi-walled carbon nanotube (CNT) surface-modified on at least one or both obtained through the above-described CNT / GMP surface modification step (S200) and graphene nanoplatelets ( This is a step of preparing a nano-carbon filler by mixing an organic solvent with GNP).

In detail, the nano-carbon filler manufacturing step (S300) may sequentially proceed with the process presented below.

(a) Multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), at least one or both of which are surface-modified, are measured and provided.

The multi-walled carbon nanotubes (CNTs) and the graphene nanoplatelets (GNPs) are preferably weighed in a weight ratio of 7-9: 1-3.

(b) Measured multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are mixed with an organic solvent and ultrasonicated for 10 to 30 minutes to form a dispersion.

In the multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), at least one or both of them may be subjected to surface modification treatment.

(c) The dispersion is treated with stirring at 250 to 350 rpm for 20 to 30 hours.

(d) Filtration through a filter to obtain a nano-carbon filler.

As the filter, a micro Teflon filter or the like can be used.

(e) Vacuum drying is performed for 1 to 3 days at room temperature for the nano-carbon filler thus obtained.

The nano-carbon composite material manufacturing step (S400) is a step of preparing a nano-carbon composite material by mixing a thermosetting resin, a curing agent and a catalyst with the nano-carbon filler manufactured through the above-described nano-carbon filler manufacturing step (S300).

In detail, the nano-carbon composite material manufacturing step (S400) may sequentially proceed with the process presented below.

(a) A nano-carbon filler is mixed with an organic solvent, but ultrasonicated for 30 to 60 minutes in an ice bath to make a nano-carbon filler dispersion.

(b) After adding the catalyst to the curing agent, the catalyst is melted by heating at a temperature of 120 to 180° C. for 4 to 8 hours.

The curing agent may be one selected from fatty acid, succinic anhydride, glutaric anhydride, and a carboxylic acid-based cured product.

As the catalyst, zinc acetate dihydrate or an imidazole-based amine may be used.

(c) A curing agent with a catalyst and epoxy, a thermosetting resin, are dissolved in an organic solvent.

The epoxy is preferably a bisphenol type epoxy, and in detail, a dylpether of bisphenol A (DGEBA) epoxy may be used.

The epoxy and the curing agent are preferably mixed in an equivalent ratio of 1: 0.5 to 1.5, and the catalyst may be mixed in an amount of 1 to 3 parts by weight based on 100 parts by weight of the epoxy.

(d) A nano-carbon composite material is prepared by adding the result of step (c) to the nano-carbon filler dispersion and ultrasonicating for 10 to 30 minutes.

(e) Vacuum drying is performed for 20 to 30 hours at room temperature for the nano-carbon composite material.

A post-process of pouring the resultant prepared in this way into a mold, curing at 210° C. for 1 hour, and then performing post-curing at 230° C. for 3 hours may be performed.

Here, the nano-carbon filler may be formulated to account for 8 to 15% by weight of the total 100% by weight of the nano-carbon composite material.

In addition, used in performing each step of the pyrene copolymer synthesis step (S100), CNT / GMP surface modification step (S200), nano-carbon filler manufacturing step (S300), nano-carbon composite material manufacturing step (S400) The organic solvent is used to increase the dispersibility between raw materials, and includes at least chloroform, acetone, toluene, methylpyrrolidone (NMP), isopropyl alcohol (IPA), tetrahydrofuran (THF), and dimethylformamide (DMF). One or more may be selected and used.

The coating step (S500) is a step of forming a surface heating element in the form of a film by coating the nano-carbon composite material prepared through the above-described nano-carbon composite material manufacturing step (S400) on a support.

The support may use polyimide (PI) or Teflon.

The electrode forming step (S600) is a step of forming an electrode for applying a voltage to both ends of the film-shaped planar heating element.

The electrode may be formed of a (+) electrode and a (-) electrode.

At this time, the electrode is a silver (Ag) nanowire or silver (Ag) paste, an oxide electrode such as ITO (indium tin oxide), ZnO (zinc oxide), SnO ₂ (tin oxide), carbon nanotubes, such as graphene It may be formed of any one selected from non-oxide electrodes, and various other electrode materials having conductivity may be applied without being particularly limited thereto.

The support removal step (S700) is a step of removing the support used as the substrate and separating it from the planar heating element in the form of a film.

That is, it is possible to manufacture a flexible plane heating element through the above-described process, and in particular, it is possible to provide a flexible plane heating element exhibiting functionality suitable for a battery heater.

Hereinafter, more specific embodiments for manufacturing a flexible surface heating element according to the present invention will be described and described.

[Example 1]

Synthesis of pyrene copolymers

The following block copolymers for the synthesis of pyrene copolymers can be prepared using RAFT polymerization, which is one of living radical polymerization methods.

(1) Synthesis of polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) having a molecular weight of 15000 g/mol

After putting CTA (4 g, 0.01097 mol) and AINB (0.27 g, 0.00165 mol) in a 500 mL flask, stirring under vacuum for 30 minutes to remove moisture and foreign substances on the surface, then adding 109.7 mL of toluene and stirring at room temperature at 300 rpm. Dissolve completely. Thereafter, dimethylaminoethyl methacrylate (DMAEMA) (60.35 g, 0.38 mol) was added while flowing argon (Ar) gas. After stirring for 10 minutes, the mixture was placed in a prepared 80° C. oil bath and reacted for 14 hours. Next, methyl methacrylate (MMA) (164.74 g, 1.6455 mol) was added while flowing argon (Ar) gas, and the reaction was further conducted for 72 hours. After the reaction is finished, the reaction is stopped by putting it in an ice bath, the reactant is diluted in tetrahydrofuran (THF), and precipitated dropwise in n-hexane to obtain a white precipitate. In order to remove monomers and impurities that did not participate in the reaction, the white precipitate was again diluted with tetrahydrofuran (THF) and precipitated in n-hexane, and this process was repeated three times. After that, the obtained white precipitate is vacuum dried at room temperature for 2 days.

(2) Synthesis of polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) having a molecular weight of 25000 g/mol

Through the same process as in step (1), the amount of DMAEMA as a monomer (99.03 g, 0.63 mol) and the amount of methyl methacrylate (MMA) (274.32 g, 2.74 mol) were added.

(3) Synthesis of polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) having a molecular weight of 35000 g/mol

Through the same process as in step (1), the amount of dimethylaminoethyl methacrylate (DMAEMA) as a monomer (135.19 g, 0.86 mol) and the amount of methyl methacrylate (MMA) (383.46 g, 3.83 mol) ) as much as

(4) Synthesis of polymethyl methacrylate and polydimethylaminoethyl methacrylate (PMMA-b-PDMAEMA) block copolymer with pyrene functional group introduced

Put PMMA-b-PDMAEMA (0.5g) block copolymer in a 100mL flask, add 9.6mL of dimethylformamide (DMF), and stir for 30 minutes until completely dissolved. Add 1-(bromomethyl)pyrene (0.16g, 0.056mM) and proceed with the reaction at room temperature for 24 hours. After removing the dimethylformamide (DMF) solvent, the resultant was dissolved in 30 mL of tetrahydrofuran (THF) and put into 200 mL of nucleic acid to obtain a precipitate. The resulting product is vacuum dried at room temperature for 2 days.

That is, the pyrene copolymer can be synthesized and prepared in a form having the chemical structural formula shown in FIG. 1 through the above process, and a pyrene copolymer having a molecular weight of 10,000 to 40,000 g/mol can be synthesized.

[Example 2]

Carbon nanotube (CNT) and graphene nanoplatelet (GNP) surface modification

(1) Manufacture of carbon nanotube (CNT) coated with pyrene copolymer

Put 10 mg of carbon nanotube (CNT) in 90 mL of chloroform in a 100 mL vial and sonicate for 10 minutes. 10 mg of the pyrene copolymer is dissolved in 10 mL of chloroform, mixed with the sonicated carbon nanotube (CNT) dispersion, and then ultrasonicated for 30 minutes. Then, stirring is performed at 300 rpm for 24 hours. After stirring, unreacted block copolymers are removed through a 0.2 micrometer Teflon filter, and this process is performed three times to obtain surface-modified carbon nanotubes (CNTs) coated with a block copolymer having a pyrene functional group.

(2) Preparation of graphene nanoplatelet (GNP) coated with pyrene copolymer

It can be obtained by the same process as in (1), and at this time, instead of carbon nanotubes (CNT), graphene nanoplatelets (GNP) are used.

[Example 3]

Manufacture of nano-carbon filler

Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were put into chloroform, an organic solvent, according to the weight ratio (80:20, 60:40, 40:60, 20:80), ultrasonicated for 30 minutes, and then treated for 24 hours. while stirring at 300 rpm. Filter through a micrometer Teflon filter to obtain a hybrid nanovalent filler. The nano-carbon filler thus obtained proceeds with vacuum drying at room temperature for 3 days.

[Example 4]

Manufacture of nano-carbon composite materials

The CNT/GNP hybrid nano-carbon filler was put into chloroform at a rate of 0.05 mg/ml, and sonicated for 50 minutes in an ice bath. First, Zn acetate dihydrate (0.0787 g), a catalyst, was added to fatty acid (6.1424 g), a curing agent, and heated at 150° C. for 6 hours to dissolve the catalyst. After dissolving the curing agent and DGEBA epoxy in chloroform, they are added to the sonicated nano-carbon filler dispersion and then ultrasonicated for 10 minutes.

At this time, the curing agent and DGEBA epoxy were added in an equivalent ratio of 1:1, and the mixture paste after the dispersion process was subjected to a solvent drying process at room temperature for 24 hours in a vacuum oven before curing, and then cured the resulting product at 210 ° C for 1 hour. Post-curing was performed at 230° C. for 3 hours.

[Example 5] Characteristic evaluation of planar heating element

The paste prepared in Example 4 was poured onto a polyimide (PI) film and bar-coated to make a planar heating element. After curing the planar heating element thus prepared at 210 ° C. for 1 hour using an oven, post-curing is performed at 230 ° C. for 3 hours. As shown in Figure 2, the planar heating element made in this way is cut into a width of 2.5 cm, a length of 2.5 cm, and a thickness of 0.2 mm (excluding PI film thickness). Electrodes were formed with silver paste at both ends of the planar heating element prepared above, and a voltage was applied to evaluate heating characteristics using a thermal imaging camera.

At this time, a DC power supply (KEITHLEY 2260B-30-72 720W) was used for voltage application, and a FLIR-T62101 was used as a thermal imaging camera.

Table 1 below shows that a nano-carbon composite material according to Example 4 was prepared by setting the mixing ratio of carbon nanotubes (CNT) and graphene nanoplatelets (GNP) to 80:20 according to Example 3, and using the same, a planar heating element After manufacturing, the data showing the surface heating temperature after 30 seconds and 60 seconds according to voltage application are summarized in a table.

6 is a graph showing time-heating temperature according to application of a voltage of 4V, FIG. 7 is a graph showing time-heating temperature according to application of a voltage of 5V, and FIG. 8 is time-heating according to application of a voltage of 6V. It is a graph showing the temperature.

F-CNT / F-GNP described in Table 1 and FIGS. 6 to 8 means that a nano-carbon filler surface-modified with a pyrene copolymer is used for both CNT and GNP, and F-CNT / P-GNP is CNT This means that only nano-carbon filler surface-modified with pyrene copolymer is used.

And, P-CNT/P-GNP is a comparative group according to the present invention, which means that a nano-carbon filler without surface modification using a pyrene copolymer is used for both CNT and GNP.

This applies equally to all of the descriptions below.

characteristic nano carbon filler Applied voltage (V) 4V 5V 6V 30 seconds 60 seconds 30 seconds 60 seconds 30 seconds 60 seconds surface temperature
(℃) P-CNT/P-GNP 80:20 68 88 113 147 161 180 F-CNT/P-GNP 80:20 118 137 178 206 210 245 F-CNT/F-GNP 80:20 128 144 195 218 222 258

Table 1 and FIGS. 6 to 8 show that the surface heating temperature increases as the applied voltage increases. When a 6V voltage is applied under the condition of F-CNT/F-GNP, heat is generated up to 258 ° C. after 60 seconds. It was confirmed that, even under the condition of F-CNT/P-GNP, heat generation up to 245° C. occurred after 60 seconds when a 6V voltage was applied.

In addition, under the conditions of F-CNT/F-GNP and F-CNT/P-GNP, the heating rate of heat generation is rapidly increased to a high temperature within 30 seconds compared to the control group. In particular, when a voltage of 6V is applied, it is only about 30 seconds It shows that rapid heating occurs at a high temperature of 200 ° C or higher.

That is, in the present invention, the dispersibility of CNTs and GNPs is improved through surface modification on the CNT and GNP side through the use of a pyrene copolymer, and the interfacial contact between the epoxy resin and the nano-carbon filler is achieved by the three-dimensional structure of the nano-carbon filler. can be increased, which shows that power can be effectively converted into heat.

Figure 4 is a graph showing the tensile strength (tensile strength) according to the content of CNT and GNP in the present invention, Figure 5 is a graph showing the stress-strain (stress-strain) according to the content of CNT and GNP in the present invention .

4 and 5, it can be seen that as the content of CNT increases, the tensile strength increases and the elongation decreases. These tensile properties are also nano-carbon fillers in the nano-carbon composite material through surface modification through the pyrene copolymer. It can be said that the dispersibility of is improved.

F-CNT/P-GNP and F-CNT/F-GNP show tensile strengths of 5.65 Mpa and 5.91 Mpa, which are the highest values compared to other ratios, at the ratio of 80:20 on the nano-carbon filler side in nano-carbon composite materials. , showing the lowest elongation values of 20.7 and 20.1.

This can be attributed to the fact that the load transfer capability of the nano-carbon composite material is greatly improved by the three-dimensional structure of the nano-carbon filler as well as the utilization of the pyrene copolymer.

9 is data showing measured values of electrical conductivity according to the contents of CNT and GNP in the present invention.

Such electrical conductivity was measured using a dielectric analyzer (Dielectric analyzer, GmbHCONTECT40), and after making a circular sample having a diameter of 40 mm and a thickness of 0.5 mm, silver paste was applied to form electrodes on both sides, and then measured.

Here, too, it is shown that the electrical conductivity is improved in the condition using the pyrene copolymer compared to the non-utilizing condition.

In the nano-carbon composites under F-CNT/P-GNP conditions and F-CNT/F-GNP conditions, in particular, 3.69 × 101 (S/cm) and 4.84 × It shows the highest electrical conductivity of 101 (S / cm), and it can be confirmed that it has excellent electrical conductivity.

Table 2 below shows the sheet resistance and tensile properties according to the molecular weight and CNT content of the copolymer according to Example 1.

CNTs subjected to surface modification through 15000, 25000, and 35000 g/mol copolymers are denoted as 15k-F-CNT, 25k-F-CNT, and 35k-F-CNT, respectively.

characteristic CNT content (wt%) CNT 15k-F-CNT 25k-F-CNT 35k-F-CNT sheet resistance
(Ohm/sq.) 0.5 383 289 315 348 One 217 98.9 118 132 3 108 52.8 64.2 76.2 5 13.2 5.9 6.8 7.6 10 7.8 1.89 3.1 4.9 The tensile strength
(Mpa) 0.5 1.67 1.76 1.77 1.82 One 1.95 2.08 2.13 2.32 3 2.26 2.52 2.65 2.78 5 2.94 3.42 3.51 3.67 10 3.52 3.89 4.07 4.25 elongation rate 0.5 64.8 60.5 59 60.3 One 52 49.4 50.1 49.6 3 45.9 42.5 43.1 42.8 5 40 36.2 35.3 35.7 10 29.7 26 25.8 26.4

(1) Sheet resistance properties: The nano-carbon composite material exhibits a lower sheet resistance as the content of CNT increases, and when the copolymer is applied, the sheet resistance is lower because the dispersibility of the CNT in the nano-carbon composite material is improved.

In the case of 10wt% nano-carbon composite material, 7.8 Ohm/sq. when CNT is applied, 1.89 Ohm/sq. when 15k-F-CNT is applied, 3.1 Ohm/sq. when 25k-F-CNT is applied, and 35k-F-CNT is applied It shows a sheet resistance of 4.9 Ohm/sq.

When surface modification of CNT was performed through 15,000 g/mol copolymer, it showed the lowest sheet resistance value. Since this copolymer is a polymer, that is, an insulator, the larger the molecular weight, the thicker the coating on the CNT surface becomes. Accordingly, since the distance between the nano-carbon fillers in the epoxy becomes farther and hinders the movement of electrons, the lowest sheet resistance value is obtained when a copolymer of 15,000 g/mol with a low molecular weight is applied.

(2) Tensile properties: As the content of CNT increases, the tensile strength increases while the elongation decreases.

Tensile properties can also be expected to improve the dispersibility of CNTs in the nano-carbon composite material through surface modification of CNTs through copolymers, and can be confirmed from the results in Table 2.

In the nano-carbon composite material, the tensile strength of 3.52Mpa and elongation of 29.7 when 10wt% of CNT is applied, the tensile strength of 3.89Mpa and 26 when 15k-F-CNT is applied, and the tensile strength of 4.07Mpa when 25k-F-CNT is applied and an elongation of 25.8, and exhibits a tensile strength of 4.25Mpa and an elongation of 26.4) when 35k-F-CNT is applied, and shows the highest tensile strength and low elongation when a copolymer of 35,000g/mol is applied.

Accordingly, it can be confirmed that the properties of the planar heating element can be influenced and controlled even according to the molecular weight control of the pyrene copolymer.

The embodiments described above are merely those of preferred embodiments of the present invention and are not extremely limited to these embodiments, and various modifications and variations or modifications by those skilled in the art within the scope of the technical spirit and claims of the present invention. It will be said that the substitution of steps can be made, which will fall within the scope of the technical rights of the present invention.

Claims (33)

It is made of a nano-carbon composite material including a polymer, a nano-carbon filler, a curing agent, and a catalyst;
The polymer is an epoxy, which is a thermosetting resin,
The nano-carbon filler is a flexible surface heating element, characterized in that it comprises a multi-walled carbon nanotube (CNT) and graphene nanoplatelet (GNP). According to claim 1,
The flexible plane heating element is a flexible plane heating element, characterized in that consisting of a film form. According to claim 1,
The flexible plane heating element is flexible plane heating element, characterized in that used as a battery heater. According to claim 1,
The epoxy is a bisphenol type epoxy,
The curing agent is one selected from fatty acid, succinic anhydride, glutaric anhydride, and carboxylic acid-based cured products,
The catalyst is a flexible surface heating element, characterized in that zinc acetate dihydrate or imidazole-based amine. According to claim 4,
The epoxy is a flexible plane heating element, characterized in that the diglycidylether of bisphenol A (DGEBA) epoxy. According to claim 1,
The nano-carbon filler,
Multi-walled carbon nanotubes (CNTs) with a length of 100 to 200 μm and a diameter of 6 to 15 nm are mixed with graphene nanoplatelets (GNPs) with a diameter of 20 to 30 μm and a surface area of 30 to 60 m ² /g. A flexible planar heating element, characterized in that. According to claim 1,
The epoxy and the curing agent are 1: flexible surface heating element, characterized in that blended in an equivalent ratio of 0.5 to 1.5. According to claim 1,
The nano-carbon filler,
Flexible surface heating element, characterized in that it accounts for 8 to 15% by weight of the total 100% by weight of the nano-carbon composite material. According to claim 1,
The catalyst is a flexible surface heating element, characterized in that 1 to 3 parts by weight is blended with respect to 100 parts by weight of epoxy. According to claim 1,
The nano-carbon filler,
A flexible surface heating element characterized in that it is blended in a weight ratio of 7 to 9: 1 to 3 for multi-walled carbon nanotubes (CNT) and graphene nanoplatelets (GNP). According to claim 1,
The multi-walled carbon nanotubes (CNTs) and the graphene nanoplatelets (GNPs) are flexible surface heating elements, characterized in that at least one or both of them are surface-modified with a surface modifier made of a pyrene copolymer. According to claim 11,
The surface modifier made of the pyrene copolymer,
Flexible plane heating element, characterized in that consisting of the structure of formula (1) below.
(Formula 1)

According to claim 11,
The pyrene copolymer and the multi-walled carbon nanotube (CNT) or graphene nanoplatelet (GNP) are 1 to 3: a flexible surface heating element, characterized in that the surface modification treatment in a weight ratio of 1. According to claim 11,
The pyrene copolymer is a flexible surface heating element, characterized in that the molecular weight is 10,000 ~ 40,000g / mol. According to claim 12,
The pyrene copolymer is synthesized in a ratio of (x + y): z = 7 to 9: 1 to 3, and x is less than or equal to y. (A) synthesizing a pyrene copolymer having a pyrene functional group;
(B) providing multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), and mixing the pyrene copolymer with at least one or both of them to perform a surface modification treatment;
(C) preparing a nano-carbon filler by mixing an organic solvent with multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), at least one or both of which are surface-modified;
(D) preparing a nano-carbon composite material by mixing a thermosetting resin, a curing agent and a catalyst with a nano-carbon filler;
(E) coating a nano-carbon composite material on a support to form a planar heating element in the form of a film; Flexible planar heating element manufacturing method comprising a. According to claim 16,
(F) forming electrodes at both ends of the planar heating element in the form of a film; Flexible planar heating element manufacturing method characterized in that it further comprises. According to claim 16,
The pyrene copolymer,
Flexible planar heating element manufacturing method, characterized in that consisting of the structure of formula (1) below.
(Formula 1)

According to claim 16,
The pyrene copolymer has a molecular weight of 10,000 to 40,000 g / mol. According to claim 18,
The pyrene copolymer is synthesized in a ratio of (x + y): z = 7 to 9: 1 to 3, and x is less than or equal to y. According to claim 16,
The multi-walled carbon nanotube (CNT) has a length of 100 to 200 μm and a diameter of 6 to 15 nm,
The graphene nanoplatelet (GNP) has a diameter of 20 to 30 μm and a surface area of 30 to 60 m ² /g. According to claim 16,
The support is
Flexible plane heating element manufacturing method, characterized in that polyimide (PI) or Teflon material. According to claim 16,
In step (A),
(a) synthesizing polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA);
(b) synthesizing polymethyl methacrylate into which a pyrene functional group is introduced and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA); Flexible planar heating element manufacturing method comprising a. 24. The method of claim 23,
In step (a),
(1) After putting chain transfer agent (CTA) and 2,2'-azobis (2-methyl-propionitrile (AINB) in a flask, stirring under vacuum to remove moisture and foreign substances on the surface, and then adding an organic solvent, completely dissolving by stirring again at 250 to 350 rpm;
(2) dimethylaminoethyl methacrylate (DMAEMA) was added and stirred while flowing argon (Ar) gas, and then placed in an oil bath at 70 to 90° C. and reacted for 12 to 15 hours;
(3) adding methyl methacrylate (MMA) while flowing argon (Ar) gas and further proceeding with the reaction for 2 to 3 days;
(4) when the reaction is finished, putting it in an ice bath to stop the reaction, diluting the reactant in an organic solvent, and precipitating it in n-hexane to obtain a precipitate;
(5) vacuum drying the precipitate at room temperature for 1 to 3 days; Flexible planar heating element manufacturing method comprising a. 25. The method of claim 24,
In step (4),
After obtaining a precipitate, diluting the precipitate in an organic solvent again to remove monomers and impurities that did not participate in the reaction in the precipitate, and then precipitating in n-hexane to obtain a precipitate again; Flexible planar heating element manufacturing method characterized in that it further comprises. 25. The method of claim 24,
In step (a),
Polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) synthesized by adjusting the amount of dimethylaminoethyl methacrylate (DMAEMA) and methyl methacrylate (MMA) added A method for producing a flexible planar heating element, characterized in that for controlling the molecular weight. 24. The method of claim 23,
In step (b),
(1) Put polymethyl methacrylate and polydimethylaminoethyl methacrylate block copolymer (PMMA-b-PDMAEMA) in a flask, add dimethylformamide (DMF) solvent, stir to completely dissolve;
(2) obtaining a reactant by adding 1-(bromomethyl)pyrene and reacting at room temperature for 20 to 30 hours;
(3) removing the dimethylformamide (DMF) solvent from the reactants, dissolving them by adding an organic solvent, and adding them to hexane to obtain a precipitate;
(4) vacuum drying the precipitate at room temperature for 1 to 3 days; Flexible planar heating element manufacturing method comprising a. According to claim 16,
In step (B),
(a) adding multi-walled carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs) and organic solvents to a vial, mixing them to form a dispersion, and then first ultrasonicating for 10 to 30 minutes;
(b) After dissolving the pyrene copolymer in chloroform, mixing with the first ultrasonically treated multi-wall carbon nanotube (CNT) dispersion or graphene nanoplatelet (GNP) dispersion and second ultrasonic treatment for 10 to 30 minutes step;
(c) stirring at 250 to 350 rpm for 20 to 30 hours for a multi-walled carbon nanotube (CNT) mixture or a graphene nanoplatelet (GNP) mixture in which a pyrene copolymer is mixed;
(d) removing unreacted pyrene copolymers through a filter to obtain surface-modified multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) coated with the pyrene copolymers; Flexible planar heating element manufacturing method comprising a. According to claim 16,
In step (C),
(a) measuring and providing multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) on at least one or both of which are surface-modified;
(b) mixing multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) with an organic solvent and ultrasonicating for 10 to 30 minutes to form a dispersion;
(c) stirring the dispersion at 250 to 350 rpm for 20 to 30 hours;
(d) filtering through a filter to obtain a nano-carbon filler;
(e) vacuum-drying the nano-carbon filler at room temperature for 1 to 3 days; Flexible planar heating element manufacturing method comprising a. According to claim 29,
The multi-walled carbon nanotubes (CNT) and the graphene nanoplatelet (GNP) are 7 to 9: a method for manufacturing a flexible plane heating element, characterized in that weighed in a weight ratio of 1 to 3. According to claim 16,
In step (D),
(a) mixing the nano-carbon filler with an organic solvent and ultrasonicating in an ice bath for 30 to 60 minutes to make a nano-carbon filler dispersion;
(b) dissolving the catalyst by adding the catalyst to the curing agent and heating at a temperature of 120 to 180° C. for 4 to 8 hours;
(c) dissolving a curing agent having a catalyst and an epoxy, which is a thermosetting resin, in an organic solvent;
(d) preparing a nano-carbon composite material by adding the result of step (c) to the nano-carbon filler dispersion and ultrasonicating for 10 to 30 minutes;
(e) vacuum drying the nano-carbon composite material at room temperature for 20 to 30 hours; Flexible planar heating element manufacturing method comprising a. 32. The method of claim 31,
The epoxy is a bisphenol type epoxy,
The curing agent is one selected from fatty acid, succinic anhydride, glutaric anhydride, and carboxylic acid-based cured products,
The catalyst is zinc acetate dihydrate or an imidazole-based amine, characterized in that the flexible plane heating element manufacturing method. 32. The method of claim 31,
The epoxy and the curing agent are mixed in an equivalent ratio of 1: 0.5 to 1.5,
The catalyst is blended in an amount of 1 to 3 parts by weight based on 100 parts by weight of epoxy,
Of the total 100% by weight of the nano-carbon composite material, the nano-carbon filler is a flexible surface heating element manufacturing method, characterized in that it accounts for 8 to 15% by weight.

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