KR20120096451A - The process of manufacturing of electrically conductive silicone rubber heater - Google Patents

Abstract

PURPOSE: A method for manufacturing a conductive silicon rubber heating element is provided to obtain a conductive silicon rubber heating element with uniform temperature distribution using an extrusion die. CONSTITUTION: A method for manufacturing a conductive silicon rubber heating element comprises the steps of: producing a conductive silicon rubber composition by dispersing one or more kinds of conductive carbon in silicon rubber by 4-100 weight%(11), coating the conductive silicon rubber composition on core yarn through extrusion to obtain extruded conductive yarn(12), and weaving the extruded conductive yarn(13).

Description

The process of manufacturing of electrically conductive silicone rubber heater

The present invention relates to a method for manufacturing a heating element, specifically, to prepare a conductive silicone rubber composition by dispersing the conductive carbon in the silicone rubber, the silicone rubber composition is coated with a core yarn by extrusion molding (extruding) An electrically conductive yarn) is produced, and the extruded conductive yarn is made in the form of a fabric, to a method for producing a heating element.

In the heating element of the conventional conductive liquid silicone rubber, the liquid silicone rubber is excellent in low temperature characteristics and heat resistance, the liquid silicone rubber as a conductive binder is coated on a support such as a mesh form to form a conductive coating film to form a heating element. That is, since the conductive coating is formed by coating on the support, the conductive passage is a structure flowing in four directions in the form of a mesh.

However, the silicone rubber-based conductive layer formed of liquid silicone rubber has low interfacial adhesion with support fibers or metal terminals, so that the conductive coating film of the connecting portion is easily peeled off or destroyed due to repeated thermal and physical stresses, and thus is electrically disconnected and bypassed to the disconnected periphery. There is a problem that the current is concentrated and overheated, and conductive carbon is dispersed on the liquid silicone rubber, so that a precipitation problem occurs during the coating process, thereby causing a difference in thickness and electrical conductivity of the coating film formed on a support such as a mesh form. . In addition, organic solvents volatilize during the process of drying the conductive film on the support, fine pores are formed in the conductive film, and foreign matter penetrates into the formed pores and swells.

In order to solve the problems of the prior art as described above, an object of the present invention is to manufacture an extruded conductive yarn by extrusion molding, and to produce a heating element in which the conductive conductive passage is formed only in one direction in parallel with the extruded conductive yarn. In addition, the organic solvent is not used to provide an environmentally friendly heating element.

The present invention provides a conductive silicone rubber composition by dispersing conductive carbon in silicone rubber, and coating the conductive silicone rubber composition on a core yarn by extrusion molding to produce an extrusion conductive conductive yarn, and the extrusion It provides a method for producing a heating element comprising a conductive yarn in the form of a fabric.

The conductive silicone rubber heating element according to the present invention is more environmentally friendly than conventional liquid silicone rubber or a heating element using a solvent binder, and can provide a uniform temperature distribution and a safe heating element by an extrusion process for forming a uniform coating by an extrusion die. .

1 is a manufacturing process chart of the conductive silicone rubber heating element according to the present invention.
2 is a cross-sectional view of a screening die from which an extruded conductive yarn according to the present invention is produced.
3 is a state diagram of the conductive silicone rubber heating element according to the present invention.
Figure 4 is a comparison of the four-way conductive passage of the one-way conductive passage and the existing heating element according to the present invention.

The present invention relates to a method for producing a conductive silicone rubber heating element, wherein the conductive carbon selected from carbon black, graphite powder, carbon nanotubes, and chopped carbon fibers is 4 parts by weight to 100 based on silicone rubber. Dispersing in the silicone rubber in the range of parts by weight to prepare a conductive silicone rubber composition;

Coating the conductive silicone rubber composition on a core yarn by extrusion molding to produce an extrusion conductive conductive yarn;

The extruded conductive yarn provides a method for manufacturing a conductive silicone rubber heating element comprising a fabric form in which a conductive passage is formed only in one direction that is electrically parallel.

Hereinafter, the present invention will be described in more detail.

1 is a manufacturing process chart of the conductive silicone rubber heating element according to the present invention, at least one conductive carbon selected from carbon black, graphite powder, carbon nanotubes, chopped carbon fibers based on silicon rubber 4 parts by weight In the mixing step (11) of preparing a conductive silicone rubber composition by dispersing in a silicone rubber in the range of 100 parts by weight, the conductive silicone rubber composition is coated on a core yarn by extrusion molding, thereby extruding electrically conductive yarn The extrusion step 12 to be manufactured and the extrusion conductive yarn includes a weaving step 13 to be made of a fabric form in which the conductive passage is formed only in one direction that is electrically parallel.

The conductive carbon that can be used in the present invention is carbon black, graphite, carbon nanotubes, chopped carbon fibers are suitable, it is also possible to use each single material or to mix them.

In particular, when graphite powder, carbon nanotubes, and chopped carbon fibers are used in combination with carbon black, not only the conductivity can be greatly improved, but also the phenomenon in which the carbon black is fused to each other can be greatly reduced, and there is also a reinforcing effect. The characteristics of carbon black are shown from particle size, specific surface area, structure, surface properties, etc. In order to apply to the present invention, generally, the particles are small, porous and have a large surface area, and the structure is highly developed and contains less impurities. It is good and there is no restriction on the manufacturing method.

It is preferable that the primary particle diameter of the carbon black which can be used for this invention is 30 nm-70 nm, and it is preferable that DBP (dibutyl phthalate) oil absorption amount is 120 mL / 100 g-500 mL / 100 g. If the particle diameter is less than 30 nm or the DBP oil absorption is less than 120ml / 100g, the desired electrical conductivity cannot be achieved.

DBP oil absorption amount shows the degree of the structure (structure) which is a complex aggregation by the chemical and physical bonding between each particle of carbon black, and means the number of ml of DBP contained per 100 g of carbon black.

The particle size of the graphite powder is 0.5㎛ to 10㎛, battery specific resistance is preferably 0.005Ω? Cm to 0.08Ω? Cm. It is inappropriate to maintain electrical stability if it is out of the above range.

Carbon nanotubes that can be used in the present invention preferably has a particle diameter of 5nm to 90nm. If it is out of the above range because the dispersion stability is significantly reduced.

The length of the carbon fiber in the chopped state is preferably 50㎛ to 10mm. If the length is less than 50 μm, the reinforcing effect does not appear, and if it exceeds 10 mm, the orientation of the extruded conductive yarn is difficult. The addition amount is preferably 1 part by weight to 10 parts by weight with respect to the silicone rubber.

The amount of carbon black added is preferably 4 to 100 parts by weight based on 100 parts by weight of the silicone rubber, but is preferably 7 to 60 parts by weight. If the added amount is less than 4 parts by weight, the conductivity is low, and if it exceeds 100 parts by weight, the mechanical strength of the cured product may deteriorate.

The blending amount of the carbon black is reduced by the amount of graphite powder, carbon nanotubes, and chopped carbon fiber. The mixture is characterized by uniformly mixing by using a rubber kneader such as a two-stage roll mill, a banbury mixer, a dough mixer, and the like.

The roll spacing of the two-stage roll mill is preferably 2.5 mm to 20 mm. Less than 2.5mm shear strength is high, the structure of the carbon black is broken, rather the conductivity is lowered, when exceeding 20mm shear force is too weak to be difficult to disperse.

The conductive silicone rubber of this invention mix | blends said conductive carbon, processing aid, etc. with the silicone rubber containing the organopolysiloxane base polymer which becomes a rubber elastic body by hardening by heating etc. basically, a hardening | curing agent, etc. as needed.

Fig. 2 is a cross-sectional view of a screening die coating die produced by the extrusion conductive yarn according to the present invention, and the screening rubber covering coating 21 in the screening process 21 using the above-mentioned conductive silicone rubber as a coating material. The extrusion process is divided into two stages, which are divided into a molding process formed by an initial extrusion and a curing process that is cured at a high temperature. Although the molding conditions are not specifically limited in the hardening process which determines the physical property of a silicone rubber, the range of 5 second-1 hour is preferable at 100 degreeC-400 degreeC. In the case of secondary heat treatment after molding, heat treatment is preferred in the range of 1 hour to 30 hours at 150 ° C to 200 ° C. The heat treatment is to volatilize the residue of the curing agent or to improve the physical properties of the conductive silicone rubber.

The screening is a thread in the center, and the screening 21 is pulled out to the center of the die 22 through a tapered guider and a conductive silicone rubber is coated on the screening, thereby extruded conductive yarns ( 23) is made.

Although the material of the said examination is not specifically limited, Polyester yarn, glass fiber, aramid fiber, high strength PVA fiber, etc. which do not have electrical conductivity are preferable.

The fineness of the screening is preferably 500 denier to 10,000 denier. If less than 500 denier, the mechanical strength of the heating element is weak, and when the excess of 10,000 denier mesh hole of the heating element is small, clogging occurs in the insulation coating.

The conductive layer thickness of the extruded conductive yarn 23 is preferably 0.2 mm to 2 mm. If the conductive layer is thinner than 0.2mm, the mechanical strength is weak, and when the thickness exceeds 2mm, the mesh hole of the heating element is small, which causes clogging during the insulation coating.

Figure 3 is a state diagram of the conductive silicone rubber heating element according to the present invention, the fabric type is the warp yarn 31 is opened in the upper and lower groups by the opening motion of the weaving machine heald, the weft yarn is opened by the drum motion The fabric is formed by weaving and weaving the weft in which the body is enclosed in the opening to the front of the woven fabric to complete the warp and weft tissue to form a fabric, the warp of the fabric being formed into the blade tissue And, on both sides of the fabric is arranged to replace the warp of several strands with an electrical conductor line 33, the weft is characterized in that composed of an extruded conductive yarn (23).

Textile fabrics are formed by supporting the threads from each other by weaving or knitting from the threads. The fabric is formed in a weaving and knitting manner in which the thread is guided above and below adjacent yarns.

In one embodiment of the fabric, weaving is a fabric in which warp and weft yarns cross each other up and down to form a planar body of any width. It is woven into looms and is made into various fabrics depending on how the warp and weft intersect.

The main motion of the weaving process is the shedding motion, which is the process of separating the warp into two layers according to the fabric and forming a tunnel called shed, and weaving the weft through the warp according to the width of the fabric. It consists of a picking motion to pass through and a beating motion to push the weft through the opening to the front of the woven fabric as a body to complete the warp and weft tissue. In order to continue the weaving, the warp is released from the warp beam, and a certain amount of fabric is removed from the weaving area by the required speed and proper tension to the weaving part (let-off) and the required weft spacing, and the fabric is wound on the roller. Take-up is necessary.

It is characterized in that the warp of several strands on both sides of the fabric is arranged to replace the electrical conductor wire (33).

The electrical conductor wire 33 serves as an electrode wire for applying power to the weft yarn, which is an extruded conductive yarn 23.

The material of the electrical conductor wire is preferably a copper wire, an aluminum wire, a stainless steel wire, or the like.

The electrical conductor wire is preferably formed of the blade structure of the fabric.

As for the textile structure of this invention, a blade structure (lenojig) is preferable. The wing tissues are not parallel to each other, and the two warp yarns are twisted together to form an eight-shaped weft. Thus, a mesh-like crop is formed.

In particular, the extruded conductive yarns are in contact in the openings in which the electric conductor wires are twisted with each other, thereby improving contact between the electric conductor wires and the extruded conductive yarns.

The warp yarn is a general fiber yarn, but the material is not limited, and particularly, aramid fiber, fluorine fiber, flon fiber, superfiber such as ultra high tensile PVA or glass fiber, nylon, polyester fiber and the like are preferable. In particular, the glass fiber is preferably a yarn in which the yarn is twisted in several strands. This is because the twist resistance is good when the thread is twisted.

The fabric is characterized by having a fabric structure insulated and coated with the following resin.

The resin type is preferably epoxy, polyurethane, silicone, fluorine, EPDM, polyester, bituminous, oleoresin, phenol, alkyd, PVC resin and the like. In particular, silicone rubber, EPDM rubber or fluorine rubber is preferable.

4 is a comparison diagram of the one-way conductive passage and the four-way conductive passage of the existing heating element according to the present invention, comparing the four-way conductive passage state diagram 41 of the existing heating element and the one-way conductive passage state diagram 42 according to the present invention. One comparison is. The conductive path coated on the mesh support having the conventional four-way conductive path maintains the energization even in the case of a defect, and a bypass current flows to the vicinity of the defect, causing a risk of overheating due to the concentrated current. The one-way conductive passage structure according to the invention can be disconnected at the time of occurrence of a defect to prevent overheating.

<Examples>

(1) Preparation of conductive silicone rubber composition

100 parts by weight of silicone rubber, carbon black is a denka black product, 20 parts by weight, and 4 parts by weight of a curing agent. Was prepared.

(2) Preparation of Extruded Conductive Yarn

In the screening, a 1000 denier of polyester yarn and the composition prepared in the above (1) were produced by extrusion extrusion yarn with a diameter of 1 mm in the hole of the die of the extruder. The curing time was cured at 200 ° C. for 60 seconds.

(3) Preparation of conductive silicone rubber heating element

Weft yarn is used as the extruded conductive yarn prepared in the above (2), and the warp yarn is woven into two strands of polyester 500 denier (fineness), and the warp seals on both sides are alternately arranged by 10 strands of copper wire having a diameter of 0.32 mm, Weaving width 30 centimeters, weaving density 3 squares per inch. The fabric was coated with liquid silicone rubber at 0.5 mm thickness for electrical insulation purposes.

(4) The thickness of the conductive layer of the extruded conductive yarn woven in the above (3) is about 0.5 mm.

The power consumption of the conductive silicone rubber heating element manufactured by the process (1) to (4) was about 70 watts (rated voltage 220V) per meter. Average rises to 50.3 ℃ when 220V power is applied (ambient temperature 20 ℃)

(5) The temperature was measured by equally distributing the phase of the heating element manufactured in (4) above and below the length of 1m, 50.5 ℃ at the top, 50.9 ℃ at the middle, 49.5 ℃ at the bottom. The maximum and minimum deviations were 1.4 ° C, representing a 2.7% deviation.

Although described in detail with respect to preferred embodiments of the present invention as described above, those of ordinary skill in the art, without departing from the spirit and scope of the invention as defined in the appended claims Various modifications may be made to the invention. Therefore, changes in the future embodiments of the present invention will not depart from the technology of the present invention.

11: Mixing step
12: extrusion step
13: weaving stage
21: core yarn
22: die
23: extruding electrically conductive yarn
31: warp
33: electrical conductor wire
41: Four-way conduction state diagram of the existing heating element
42: one-way conductive path state diagram according to the present invention

Claims (5)

The conductive silicone rubber composition is dispersed by dispersing at least one conductive carbon selected from carbon black, graphite powder, carbon nanotube, and chopped carbon fiber in the silicone rubber in a range of 4 parts by weight to 100 parts by weight based on the silicone rubber. A mixing step of preparing;
An extrusion step of coating the conductive silicone rubber composition on a core yarn by extrusion molding to produce an extrusion conductive conductive yarn;
The extrusion conductive yarn weaving step consisting of a fabric form in which the conductive passage is formed only in one direction that is electrically parallel type;
Method for producing a conductive silicone rubber heating element comprising a. The method of claim 1,
The screening is any one or more of polyester yarn, glass fiber, aramid fiber, high-strength PVA fiber, the screening fineness is 500 to 10000 denier manufacturing method of a conductive silicone rubber heating element. The method of claim 1,
The conductive layer thickness of the extruded conductive yarn is 0.2mm to 2mm manufacturing method of the conductive silicone rubber heating element, characterized in that. The method of claim 1,
The above-described fabric type is the opening of the warp 32 in the upper and lower groups by the opening movement of the weaving heald, the weft through the opening of the warp through the weft movement, the weft of the body in the opening in front of the woven fabric The fabric is formed by successive repetition of body needle movement to complete the tissue of warp and weft by pushing it up to form a fabric, and the warp of the fabric is formed into a blade structure, and the warp of several strands on both sides of the fabric is connected to the electric conductor wire ( 33) and a method of manufacturing a conductive silicone rubber heating element, characterized in that the weft is composed of an extruded conductive yarn (23). The method of claim 1,
The length of the finely chopped carbon fiber is a method for producing a conductive silicone rubber heating element, characterized in that 50㎛ to 10mm.

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