KR101209174B1 - Conductive ink composition for heating unit using carbon nanotube - Google Patents

Abstract

PURPOSE: A conductive ink composition is provided to prevent decrease of durability due to change of resistance value because of excellent electric resistance stability and to prevent separation from an object generated during processing a product because of excellent adhesion with an object. CONSTITUTION: A conductive ink composition using carbon nanotubes comprises 100.0 parts by weight of organic solvent, 0.5-3.5 parts by weight of carbon nanotubes, 15-20 parts by weight of carbon black, 0.05-0.5 parts by weight of an anionic dispersant, 0.1-2 parts by weight of a non-ionic surfactant, and 30-70 parts by weight of a polyester-based resin. The diameter of the carbon nanotubes is 15-25 nm and the length is 1-25 micron. The granularity of the carbon black is 3-10 micron. The phosphate of the anionic dispersant is phosphate. The organic solvent is butyl cellosolve acetate. [Reference numerals] (AA) Laminex film(P.E.T); (BB) Copper Booth bar EVA, EEA high temperature bonding; (CC) Silver Booth bar; (DD) Carbon heating unit; (EE) Base film

Description

Conductive Ink Composition for Heating Unit Using Carbon Nanotube}

The present invention relates to a conductive ink composition for a heating element using carbon nanotubes including carbon nanotubes, carbon black, anionic dispersants, organic solvents, nonionic surfactants and polyester resins.

The planar heating element is classified into a metal heating element and a nonmetallic heating element. In recent years, the non-metallic heating element is mostly used according to weight reduction and sheeting.

In particular, the non-metallic heating element is manufactured with an ink composition using a carbon material having a low cost, and mainly carbon black or graphite is used.

Carbon black or graphite particles are present in a random or spherical form, the ink composition prepared according to this form is because the particles are easily agglomerated or separated from each other, the coating distribution of the ink is not uniform when printing with a heating layer. As a result, the resistance value of the heat generating layer is not uniform, so that the heat generating element of the portion having a high heat generation temperature deteriorates earlier than the portion having a low heat generation, thereby causing a problem of shortening the life. In addition, since the adhesion between the adherend and the heat generating layer is lowered, a phenomenon of peeling or peeling off easily appears, thereby deteriorating resistance stability and durability.

In addition, the planar heating element generally used has a low resistance value, so that the carbon black and graphite content must be increased to produce the planar heating element. In this case, the adhesion and printability of the carbon material and the resin are not balanced. It does not function properly.

Recently, ink compositions using new materials such as carbon nanofibers and carbon nanotubes, which are high-purity carbon materials, have been introduced to solve such problems. However, there are disadvantages in that dispersibility and expensive materials are used.

On the other hand, Republic of Korea Patent Publication No. 10-2008-0088712 40 to 80% by weight of the non-aqueous mixed solvent; 15-50 wt% of copper nanoparticles; 0.01 to 5 weight percent dispersant; And 1 to 20% by weight of a humectant.

Republic of Korea Patent Publication No. 10-2008-0088712

The present inventors have tried to develop a conductive ink composition for a heating element excellent in mechanical properties, thermal stability and adhesion. As a result, a heating element was manufactured using a conductive ink composition for a heating element including carbon nanotubes, carbon black, anionic dispersant, an organic solvent, a nonionic surfactant, and a polyester-based resin. It prevents degradation of durability (evenness of heat generation temperature) due to the change of value, and prevents falling off with adherends generated during processing of products due to excellent adhesion with adherends, and prevents electrical short or spark caused by falling out. By confirming the effect to be prevented, the present invention has been completed.

Accordingly, an object of the present invention is to provide a conductive ink composition for a heating element using carbon nanotubes.

Another object of the present invention to provide a method for producing a conductive ink composition for a heating element using carbon nanotubes.

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

According to an aspect of the present invention, the present invention provides a conductive ink composition for a heating element using carbon nanotubes including carbon nanotubes, carbon black, anionic dispersants, organic solvents, nonionic surfactants and polyester resins. .

The present inventors have tried to develop a conductive ink composition for a heating element excellent in mechanical properties, thermal stability and adhesion. As a result, a heating element was manufactured using a conductive ink composition for a heating element including carbon nanotubes, carbon black, anionic dispersant, an organic solvent, a nonionic surfactant, and a polyester-based resin. It prevents degradation of durability (evenness of heat generation temperature) due to the change of value, and prevents falling off with adherends generated during processing of products due to excellent adhesion with adherends, and prevents electrical short or spark caused by falling out. The effect to be prevented was confirmed.

As used herein, the term “heating element” is used interchangeably with the term “planar heating element”, and an application field of the heating element may be applied to the construction and construction field, industrial equipment field, military field, household goods field, concentrated fisheries field or automobile field, and the like. , The heating element is floor heating, wall heating, heating frame, snow melting system, plumbing insulation, military equipment heating, military supplies heating, portable heating mats, heating clothing, heating shoes, agricultural products drying racks, livestock floor heating, plastic house freezing prevention, aging A heating element used for cultivation, automobile seat heating, automobile steering wheel heating, and the like, more preferably the heating element is a heating film.

According to a preferred embodiment of the present invention, the composition of the present invention is 0.5 to 3.5 parts by weight of carbon nanotubes, 15 to 20 parts by weight of carbon black, 0.05 to 0.5 parts by weight of anionic dispersant, and nonionic interface based on 100 parts by weight of organic solvent. 0.1-2 parts by weight of active agent and 30-70 parts by weight of polyester resin, more preferably 0.6-3.3 parts by weight of carbon nanotube, 17-19 parts by weight of carbon black, and anionic dispersant based on 100 parts by weight of organic solvent. 0.1-0.2 parts by weight, 0.5-1 part by weight of nonionic surfactant, and 40-60 parts by weight of polyester resin.

In the composition of the present invention, when the components are included in the content, it has an excellent effect of adhesion, prevention of falling off with the adherend, electrical resistance stability and exothermic temperature distribution.

According to another preferred embodiment of the present invention, the carbon nanotubes included in the composition of the present invention is 15-25 nm in diameter and 1-25 μm in length, more preferably 18-22 nm in diameter and 1-25 μm in length. .

According to another preferred embodiment of the present invention, the carbon black included in the composition of the present invention has a particle size of 3-10 μm.

The anionic dispersant included in the composition of the present invention may use various anionic dispersants known in the art, but is preferably a phosphate ester salt.

The organic solvent included in the composition of the present invention may use a variety of organic solvents known in the art, but preferably butyl cellulsolve acetate.

The nonionic surfactant included in the composition of the present invention may use various nonionic surfactants known in the art, but is preferably a silicone glycol copolymer.

A feature of the present invention is an ink composition in which CNT composites and carbon materials are dispersed in a small amount, and, in spite of excellent conductivity, CNT, which has been difficult to be applied due to dispersibility problems, has high conductivity through a high dispersion treatment method. Maximized overcoming the shortcomings. This can reach a low resistance value by mixing a small amount of CNT content and a relatively low content of carbon material, the high specific surface area and the mesh structure of the CNT serves to hold the mixed carbon material to have a uniform distribution of ink composition Because I could. As a result, it has better electrical resistance stability than heat-generating inks based on existing carbon, and has excellent adhesion to adherends when manufacturing products, resulting in dropout from adherends generated during product processing, and bending during construction of finished products. It is possible to prevent the occurrence of electric short circuit or spark, which may occur due to the dropping of the adherend due to bending, or the like, and the deterioration in durability due to the change in the resistance value (the lowering of the uniformity of the heating temperature). In addition, it is possible to produce a planar heating element excellent in durability by using an ester-based resin having excellent mechanical properties, thermal stability and adhesion.

According to another aspect of the present invention, the present invention provides a method for producing a conductive ink composition for a heating element using carbon nanotubes comprising the following steps: (a) adding a carbon nanotube and an anionic dispersant to an organic solvent Dispersing carbon nanotubes; (b) mixing and milling carbon black, a nonionic surfactant, and a polyester-based resin into the product of step (a); And (c) adding an organic solvent to the resultant of step (b) to adjust the viscosity to have a value of 3000-6000 cps.

Method for producing a conductive ink composition for a heating element of the present invention is to produce a conductive ink composition for a heating element using the carbon nanotubes of the present invention described above, in order to avoid excessive complexity of the specification according to the repeated description, The description is omitted.

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

(Iii) The present invention relates to a conductive ink composition for a heating element using carbon nanotubes containing carbon nanotubes, carbon black, anionic dispersants, organic solvents, nonionic surfactants and polyester resins.

(Ii) Despite the excellent conductivity, CNTs, which were difficult to apply due to dispersibility problems, were overcome by the high dispersion treatment method to maximize the conductivity with a small amount of CNTs.

(Iii) In addition, a small amount of CNT content and a relatively low content of carbon material can be mixed to reach a low resistance value, and the high specific surface area and the mesh structure of the CNT serve to hold the mixed carbon materials, thereby providing a uniform ink composition. Has a distribution of.

(Iii) As a result, it has better electrical resistance stability than exothermic ink mainly composed of carbon, and has excellent adhesion to adherends when manufacturing products. Electric short circuit or spark that may occur due to dropping of the adherend due to bending or bending at the time, and durability deterioration (decreasing uniformity of heat generation temperature) due to change in resistance value may be prevented in advance. In addition, it is possible to produce a planar heating element excellent in durability by using an ester resin having excellent mechanical properties, thermal stability, and adhesion.

1 is a photograph comparing the comparative example with that the heating layer of the heating film prepared by using the ink composition prepared according to an embodiment of the present invention is not broken or peeled off.
Figure 2 shows the structure of the heating element produced using the ink composition prepared according to the embodiment of the present invention.
Figure 3 is a photograph showing a heating film prepared using a comparative example and an ink composition prepared according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood that the scope of the present invention is not limited by these examples in accordance with the gist of the present invention, and it is to be understood by those skilled in the art that the present invention is not limited thereto It will be obvious.

Example

Throughout this specification,% used to refer to the concentration of a particular substance is (weight / weight)% solids / solid, (weight / volume)%, and liquid / Liquid is (volume / volume)%.

Preparation Example 1: Preparation of a conductive ink composition for a heating element using carbon nanotubes

To prepare a carbon nanotube (CNT) heating ink of the present invention with the composition shown in Table 1, which was used as Example 1.

Raw material name Part ratio(%) manufacturer Remarks Carbon nanotubes 1.5 1.2 Note) CNT Tube Carbon black 13.7 10.7 Columbian Chemicals Spherical Dispersants 1
(Phosphate ester salt) 0.12 0.1 Airproduct - Butyl Cellulose Acetate 75 58.4 Sigma aldrich - Dispersants 2
(Silicon Glycol Copolymer) 0.62 0.5 Dow corning - Polyester resin 37.5 29.2 Unitika ltd - Gross weight 124.7 100 - -

Specifically, the manufacturing process is mechanical and physical by first adding 6 g of CNTs having a diameter of 20 nm and a length of 1-25 μm, 0.5 g of anionic dispersant (phosphate ester salt), and 300 g of an organic solvent (butyl cellulose solution acetate). Dispersed by the method, 55 g of carbon black having a particle size of 3-10 μm, 2.5 g of a nonionic surfactant (silicon glycol copolymer), and 150 g of a polyester-based resin were mixed, stirred and milled again with a bead mill. Next, the planar heating element ink composition was prepared by adjusting the viscosity through an organic solvent (butyl cellulose solution acetate).

In addition, as a comparative example, the ink composition prepared according to the content of the planar heating element and the dispersed carbon nanotubes using only carbon black was prepared as shown in Table 2:

Raw material name Comparative example Example 2 Example 3 Example 4 Example 5 Part Part Part Part Part Dispersed Carbon Nanotubes - 2 4 6 10 Carbon black 70 55 55 55 55 Dispersants 1
(Phosphate ester salt) 0.5 0.5 0.5 0.5 0.5 Butyl Cellulose Acetate 300 300 300 300 300 Dispersants 2
(Silicon Glycol Copolymer) 2.5 2.5 2.5 2.5 2.5 Polyester resin 150 150 150 150 150

Experimental Example : Characteristic test of conductive ink composition for heating element using carbon nanotube

Various properties were analyzed for the planar heating element ink composition of Example 1, and the results are shown in Table 3:

SPEC. Unit of measure result Specification (equipment) Surface resistance Ω / □ 70-90 Bar coater no.14 Viscosity CPS / 25 ℃ 4,500 ~ 5,500 VISCOTECH
LVT (L3 10 rpm) Drying conditions ℃ / Min 140/2 Frenzy Adhesion Great HOT PRESS 100kgf
100 ℃ / 30SEC color black Visually

In addition, various properties were analyzed for the planar heating element ink compositions of Comparative Examples and Examples 2 to 5, and the results are shown in Table 4:

Analysis item Comparative example Example 2 Example 3 Example 4 Example 5 Surface resistance (Ω / □)
(Bar coater no.14) 80-150 200-250 100-150 70-90 50-70 Viscosity (cps) 10,000-15,000 3,000-5,000 3,000-5,000 4,000-6,000 10,000-15,000 De-Lami Test
(100 ℃, 100 kgf / ㎠) Peel off coating Good Good Good Good Printability usually Good Good Good Good Adhesion usually Good Good Good Good Coating hardness (H) 2-3 3-4 3-4 3-4 3-4 Resistance stability
(20 ℃ to 150 ℃) -16.8% -10.8% -9.8% -9.2% -9.8% Storage stability
(month) 3-6 6-12 6-12 6-12 6-12 Exothermic temperature distribution Instability Uniformity Uniformity Uniformity Uniformity

Property analysis in Tables 3 and 4 was carried out as follows:

1) Surface resistance measuring method: Measuring instrument HIOKI 3834 resistance measuring instrument (measurement jig), the interval between the measuring jig was 25 mm horizontally and vertically.

2) Viscosity: Measured by VISCOTECH LVT (L3 10 rpm), the temperature 25 ℃, 2 min was measured based on the viscosity at this time.

3) Curing condition: It is based on hot air drying furnace, temperature is 140 ℃ and time is 1 min 30 sec-2 min.

4) Adhesion TEST (DE-lami): This test is to test the adhesion of ink to PET film, which is the outside of the heating film.

 PET film: 200 was applied to a thickness of 8-10 μm by a bar coating (gravure printing) or gravure printing method to 200 mm size and cured under the above curing conditions.

-HEATING TEST (Hot Laminating): HEATING TEMP: 100 ℃, PRESS (kgf): 100kgf, PRESS TIME: 30sec

  The hot laminating film of the same size as the cured test piece was placed on the cured ink and the heating plate, and subjected to hot press under the conditions described above, and then, after standing at room temperature for 1 hour, the two test pieces were peeled off. . At this time, there should be no ink on the laminated film.

5) Resistance Stability: The resistance stability was evaluated by measuring the change in resistance value when the ink composition was cured on a PET film and raised from 20 ° C to 150 ° C as described above.

6) Exothermic Temperature Distribution: The exothermic temperature distribution was measured using an infrared thermal imaging camera (FLIR_E60, Sweden).

As can be seen in Tables 3 and 4, the composition of the present invention showed excellent properties as a planar heating element ink composition. As can be seen from the resistivity of the composition of the present invention, even if a small amount of CNT is added, it may have a lower resistivity than the ink composition of a carbon material, and a viscosity within a range of 4,000 to 6,000 cps suitable for printing during heating film manufacturing. It has a suitable viscosity and printability as a printing method of PET film in heating film printing process. In addition, it was found that the adhesion between the coating layer and the film is excellent in the delaminating test, which is one of important physical properties.

And, as can be seen in Figure 1 attached below, in the existing carbon-based product line (base) product, there was a problem of the risk of fire due to electrical performance due to the decline in durability performance, insufficient adhesion to PET film, However, when coated with the composition of the present invention it can be confirmed that the heat generating layer is not broken or peeled off by maintaining the network formation of the carbon material and carbon nanotubes by the structural aspect of the CNT. In addition, due to the uniformity of nanoparticle size, there is less variation in electrical resistance due to excellent conductivity and thermal conductivity compared to the conductive ink of the existing carbon base, and uniform thermal conductivity and durability without changing the electrical characteristics by long time use. It has a strong advantage (see Table 4).

Preparation Example 2: Structure of a heating element manufactured using the conductive ink composition for a heating element using the carbon nanotubes of the present invention

As can be seen in Figure 2, gravure printing the exothermic composition solution added CNT on the PET film and each heating element is connected in parallel with silver paste (Silver Paste), after forming the electrode with a copper ribbon (Copper Ribbon) EVA / PET The state-of-the-art far-infrared heating element laminated with the film was able to be processed.

As described above in detail a specific part of the present invention, it is apparent to those skilled in the art that the specific technology is only a preferred embodiment, which is not intended to limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.

Claims (8)

0.5-3.5 parts by weight of carbon nanotubes, 15-20 parts by weight of carbon black, 0.05-0.5 parts by weight of anionic dispersant, 0.1-2 parts by weight of nonionic surfactant, and polyester resin 30-70 based on 100 parts by weight of organic solvent. Conductive ink composition for a heating element using a carbon nanotube, including a weight part.
delete The composition of claim 1, wherein the carbon nanotubes are 15-25 nm in diameter and 1-25 μm in length.
The composition of claim 1, wherein the carbon black has a particle size of 3-10 μm.
The composition of claim 1, wherein the anionic dispersant is a phosphate ester salt.
The composition according to claim 1, wherein the organic solvent is butyl celusolve acetate.
The composition of claim 1, wherein the nonionic surfactant is a silicone glycol copolymer.
It comprises the following steps, 0.5-3.5 parts by weight of carbon nanotubes, 15-20 parts by weight of carbon black, 0.05-0.5 parts by weight of anionic dispersant, 0.1-2 parts by weight of nonionic surfactant, and 100 parts by weight of organic solvent, and Method for producing a conductive ink composition for a heating element using carbon nanotubes, including 30 to 70 parts by weight of polyester resin:
(a) dispersing carbon nanotubes by adding a carbon nanotube and an anionic dispersant to an organic solvent;
(b) mixing and milling carbon black, a nonionic surfactant, and a polyester-based resin into the product of step (a); And
(c) adding an organic solvent to the resultant of step (b) to adjust the viscosity to have a value of 3000-6000 cps.

Images