WO2008132876A1

WO2008132876A1 - Marking ink of electrical wire

Info

Publication number: WO2008132876A1
Application number: PCT/JP2008/053733
Authority: WO
Inventors: Takeshi Kamata; Keigo Sugimura; Daikichi Kinoshita
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2007-04-20
Filing date: 2008-02-26
Publication date: 2008-11-06
Anticipated expiration: 2009-10-20
Also published as: JP2008266453A

Abstract

The present invention is to provide an ink for marking an electrical wire without clogging of a nozzle of a marking apparatus. The marking ink is ejected to an outer surface of the electrical wire by a prescribed amount in a droplet. The marking ink contains 100 parts by weight of an ink main material, which contains a solvent, an acrylic resin and a coloring material, and 2-10 parts by weight of ethylene glycol.

Description

DESCRIPTION

MARKING INK OF ELECTRICAL WIRE

Technical Field

The present invention relates to an ink for marking an outer surface of an electrical wire with a prescribed amount of the ink.

Related Art

A motor vehicle is equipped with a variety of electronic devices. Electrical power or electrical signal is fed to the electronic devices via a wiring harness from a power supply or a computer,- respectively. The wire harness includes a plurality of electrical wires and a connector attached to ends of the electrical wires. The electrical wires each include a conductive core wire and an insulation covering the core wire. The connector includes a plurality of terminals and a connector housing. Assembly of the wiring harness is made in a manner that the electrical wires are cut by a prescribed length and the insulations of the end portions of the electrical wires are stripped and the terminals are connected to the stripped portions and the terminals are inserted into the connector housing.

Each of the electrical wires of the wiring harness is identified with respect to a diameter of the core wire, a material of the insulation about heat resistance, and a purpose of use. The purpose of use of the electrical wire is classified into a control system such as air bag, ABS (Antilock Brake System) , speed, and a power system.

The insulation of the electrical wire is formed with a synthetic resin containing a coloring material by an extrusion apparatus (for example, JP,H5-111947-A, JP, H6-119833-A, JP,H9-9205β-A) . In the conventional method, it is necessary to stop the extrusion apparatus when a color of an outer surface of the electrical wire is changed. This operation increases a time for manufacturing the electrical wire and decreases productivity thereof.

As an alternative way, the color of the insulation can be changed by adding a next coloring material to a current coloring material of the extrusion apparatus. This operation causes the electrical wire having a portion mixed with the previous color and the next color, resulting in low yield of the electrical wire. The applicant of the present invention proposed to color an outer surface of an electrical wire covered with an insulation of a plain color in order to improve the productivity of the electrical wire and reduce the loss of the electrical wire (WO2003/019580) . The same applicant also proposed an apparatus for marking an outer surface of an electrical wire by ejecting a prescribed amount of an ink toward the outer surface thereof (JP, 2004-134371-A) .

The marking apparatus disclosed in JP, 2004--134371-A utilizes a marking ink containing an organic solvent, a PMMA (polymethyl methacrylate) resin as a binder, a coloring material, and a dispersing agent. The marking apparatus is disposed in a step of cutting the electrical wire or a step of attaching a terminal to an end of the electrical wire.

The conventional marking apparatus utilizes a fast-drying type ink. When the marking apparatus is stopped for a certain period of time, the ink remained in the nozzle of the marking apparatus is exposed to air and solidified, and the solidified ink clogs the nozzle. The clogging of the nozzle is solved by washing the nozzle, resulting in low production of the electrical wire. Even though the nozzle is not completely clogged by the solidified ink, the solidified ink interferes a prescribed direction of ejection of the ink to the electrical wire, so that a design of pattern is disturbed.

Disclosure of the Invention An object of the present invention is to provide a marking ink of an electrical wire without clogging a nozzle.

According to a first aspect of the present invention, an ink for marking an outer surface of an electrical wire with ejection of a prescribed amount of the ink, contains 100 parts by weight of an ink main material, which contains a solvent, an acrylic resin, and a coloring material, and 2-10 parts by weight of ethylene glycol.

Brief Description of the Drawings

FIG. 1 is a side view of an apparatus for forming a mark on an electrical wire with a marking ink of an embodiment of the present invention;

FIG. 2 is a sectional view of an ink-ejecting unit of the marking apparatus taken along line II-II of FIG. 1;

FIG. 3 is a sectional view of a marking nozzle of the ink-ejecting unit of FIG. 2;

FIG. 4A is a perspective view of the electrical wire marked with a dot formed with the marking apparatus of FIG. 1; and

FIG. 4B is a plan view of the electrical wire of FIG. 4A.

Best Mode for Carrying out the Invention

FIGS. 1-4 show an apparatus for marking an electrical wire with a marking ink, hereafter referred to as ink, of the present invention. The marking apparatus 1 forms a mark 6 on an outer surface 3a of the electrical wire 3. The electrical wire 3 includes a conductive core wire 4 and an insulation 5 as shown in FIG. 4A, and is wired in a motor vehicle in a form of a wiring harness. The core wire 4 has a plurality of metal wires or a single wire. The insulation 5 is formed with a synthetic resin such as polyvinylchloride (PVC) or polyolefin (PE, PP) and covers the core wire 4. An outer surface of the insulation 5 is thus the outer surface 3a of the electrical wire 3.

The insulation 5 has a plain color P of the synthetic resin itself or the synthetic resin containing a coloring agent. When the plain color P is originated from the synthetic resin itself, the plain color P is so-called color-free. The outer surface 3a of the electrical wire 3 thus has a color of color-free or white.

The outer surface 3a of the electrical wire 3 has the mark

6 having a plurality of dots 7 as depicted in FIGS. 4A and 4B. The dots 7, which are indicated by diagonal lines, have a color

B different from the plain color P and are formed in the longitudinal direction of the outer surface 3a of the electrical wire 3 with a prescribed distance between the adjacent dots 7.

A bundle of the electrical wires 3 forms the wiring harness connected with a connector so that the wire harness supplies electrical signal or power to electronic devices of the motor vehicle.

Each of the electrical wires 3 is identified with the color

B of the dots 7. FIGS. 4A and 4B show the same color B but each dot 7 can have a color ^■ different from each other. The identification by means of the color B is intended for identifying kind and purpose of use of the electrical wire 3.

Referring to FIG. 1, the marking apparatus 1 includes a frame 10, a guide roller 11, a pair of pulling rollers 12, a correcting unit 13, a stretching unit 14, an ink-ejecting unit

15, a duct 16, an encoder 17, a cutter 18, and a control device 19 .

The frame 10 is placed on a floor of a factory and extends horizontally. The guide roller 11 is disposed on one end of the frame 10 and wound with the long electrical wire 3 unmarked with the mark 6. The guide roller 11 sends forth the electrical wire 3 through the correcting unit 13, the stretching unit 14, the ink-ejecting unit 15, the duct 16, the encoder 17, and the cutter 18, in its order.

The pulling rollers 12 are disposed on the other end of the frame 10 and vertically opposed to each other and pull the electrical wire 3 from the guide roller 11. The pulling rollers 12 thereby stretch and move the electrical wire 3 relative to a plurality of marking nozzles 31 in a direction K indicated by an arrow in FIG. 1. The correcting unit 13 is disposed downstream of the guide roller 11 and includes a main body 20, a plurality of first rollers 21, and a plurality of second rollers 22.

The first and second rollers 21, 22 are supported with the main body 20 and horizontally disposed in the direction K. The first and second rollers 21, 22 are alternately disposed above and below the electrical wire 3 as shown in FIG. 1. The first and second rollers 21, 22 of the correcting unit 13 hold the electrical wire 3 therebetween to stretch the electrical wire 3 with a frictional force. The correcting unit 13 applies a first urging force Hl against the stretching force in the direction K applied by the pulling rollers 12. It is apparent that the stretching force is larger than the first urging force Hl.

The stretching unit 14 is disposed between the correcting unit 13 and the ink-ejecting unit 15. The stretching unit 14 includes a pair of guide-roller frames 23, a pair of guide rollers 24, a transfer-roller frame 25, a transfer roller 26, and an air cylinder 27.

The guide-roller frames 23 are fixed to the frame 10 and disposed spaced each other along the direction K of movement of the electrical wire 3. The guide rollers 24, which are rotatably connected to the guide-roller frames 23, support the electrical wire 3 with outer surfaces thereof and guide the electrical wire 3 in the direction K.

The transfer-roller frame 25 is disposed between the guide-roller frames 23. The transfer roller 26 is rotatably attached to the transfer-roller frame 25 and disposed above the electrical wire 3 and vertically movable with respect to the electrical wire 3.

The air cylinder 27 includes a cylinder main body 28 and an extensible rod 29, and is fixed on the transfer-roller frame

25. The transfer roller 26 is attached to the extensible rod

29. When the extensible rod 29 is downwardly moved by the air cylinder 27, the transfer roller 26 is downwardly moved to urge the electrical wire 3 with a second urging force H2 which is smaller than the first urging force Hl.

When the electrical wire 3 is cut with a pair of blades 48, 49, the pulling rollers 12 stop movement of the electrical wire 3. An inertial movement of the guide roller 11 feeds the electrical wire 3 to some extent in the direction K, causing a sagging of the electrical wire 3. The transfer roller 26 downwardly pushes the electrical wire 3 and stretches the sagging electrical wire 3 with the second urging force H2.

The ink-ejecting unit 15 is disposed between the stretching unit 14 and the duct 16. Referring to FIG. 2, the ink-ejecting unit 15 includes a unit main body 30 , the plurality of the marking nozzles 31, a plurality of ink reservoirs 32, and a pressurized gas supply unit 33. The unit main body 30 is fixed to the frame 10 of the marking apparatus 1 and holds the plurality of the marking nozzles 31.

The marking nozzles 31 each eject a prescribed amount of a liquid ink, which is supplied from the associated reservoir 32, onto the outer surface 3a of the electrical wire 3 to form the mark 6. Referring to FIG. 3, the marking nozzle 31 includes a cylindrical nozzle main body 34, an insert member 35, an ink inlet 36, a tip portion 54, and a valve unit 38. The insert member 35 is cylindrical in shape and has an ink passage 39 therein. The ink passage 39 is filled with the ink supplied from the ink reservoir 32 via the ink inlet 36.

The tip portion 54 includes a first nozzle member 37, a second nozzle member 50, and a connection tube 51. The first nozzle member 37 is cylindrical in shape and communicated with the ink passage 39 and guides the ink outside of the marking nozzle 31. The first nozzle member 37 is formed with stainless steel .

The second nozzle member 50 is cylindrical in shape and made of polyether etherketone (PEEK) and communicated with the insert member 35 through the first nozzle member 37. The second nozzle member 50 has an inner diameter smaller than that of the

/ first nozzle member 37 , and is coaxially connected with the first nozzle member 37 and disposed closely to the electrical wire 3. The ink flows inside the first and second nozzle member 37, 50 which are watertight each other. Since the inner diameter of the second nozzle member 50 is smaller than that of the first nozzle member 37, one end face 50a of the second nozzle member 50 forms a step facing an end face of the first nozzle member 37.

A part of an end portion of the first nozzle member 37 and the second nozzle member 50 are removably received inside of the connection tube 51. The connection tube 51 is cylindrical in shape and made of a fluorocarbon resin. The valve unit 38 includes a coil 40, a valve main body 41, and a coil spring 42. The coil 40 is received in the insert member 35 disposed outside of the ink passage 39. An electric current is supplied to the coil 40. The valve main body 41 includes a conductive main portion 43 and a valve 44. The main portion 43 includes a cylinder portion 45 and a disk portion 46 connected to the cylinder portion 45. The main portion 43 or the valve main body 41 is received in the nozzle main body 34 and slidable in the longitudinal direction of the nozzle main body 34. The valve 44 is attached to the disk portion 46 of the main portion 43 and faces a base portion 37a of the first nozzle member 37. The valve 44 contacts and separates from the base portion 37a of the first nozzle member 37 with movement of the main portion 43 energized with the current supplied to the coil 40.

When the valve 44 contacts the base portion 37a, the valve 44 stops entering of the ink of the ink passage 39 into the first nozzle member 37. When the valve 44 separates from the base portion 37a, the valve 44 allows the ink to flow through the first and the second nozzle member 37, 50 so that the ink is ejected to the outer surface 3a of the electrical wire 3 through the tip portion 54. The valve 44 is positioned at an opening position and a close position indicated by a dotted-dashed line (-..-) and a solid line, respectively. The coil spring 42 urges the disk portion 46 toward the base portion 37a.

The marking nozzles 31 are attached to the unit main body 30 and each disposed in the direction K indicating moving direction of the electrical wire 3. Five marking nozzles 31 are disposed in FIG. 1. The marking nozzles 31 are supported with the unit main body 30 so as to eject the prescribed amount of the ink toward the uppermost portion of the electrical wire 3. Each axis of the first nozzle members 37 is pointed to the uppermost portion of the electrical wire 3. The ink reservoirs 32 each are connected to the associated marking nozzle 31. The ink reservoirs 32 are disposed between gas supply conduits 58 and ink supply conduits 59. A pressurized gas is supplied from the gas supply unit 33 to the ink reservoirs 32 through gas valves 62 and the gas supply conduits 58. The valves 62 control flow of the pressurized gas.

The ink supply conduits 59 are connected to the ink inlets 36 of the marking nozzles 31 and transfer the ink to the marking nozzles 31. The gas supply unit 33 can supply the plurality of the ink reservoirs 32.

The ink-ejecting unit 15 is controlled with the control device 19 so as to open the valves 62 and keep pressures in the ink reservoirs 32 at a prescribed level and supply the ink to the marking nozzles 31. The ink supplied to the associated marking nozzle 31 is ejected toward the electrical wire 3 by the prescribed amount through the ink passage 39. The ink is a liquid material containing a solvent dissolving or dispersed with a coloring material (industrial organic compound) . The organic compound is a dye or a pigment (mostly synthesized organic compound) .

The marking ink is thus a coloring liquid or a coating material.

In the coloring liquid, the dye is dissolved or dispersed in the solvent, and in the coating material, the pigment is dispersed in the solvent. When the coloring liquid is applied to the outer surface 3a of the electrical wire 3, the dye penetrates into the insulation 5. When the coating material is applied, the pigment adheres to the outer surface 3a of the insulation 5 without penetration. The outer surface 3a of the electrical wire 3 is thus dyed with the dye or coated with the pigment . It is preferable to use the solvent having an affinity with the synthetic resin to allow the assured penetration of the dye into the insulation 5 and the assured adherence of the pigment to the outer surface 3a. The ink is ejected to the outer surface 3a of the electrical wire 3 with a droplet. The duct 16 is tubular in shape and disposed downstream of the ink-ejecting unit 15. The duct 16 includes an evacuating means such as a vacuum pump to evacuate the solvent of the marking ink after the outer surface 3a of the electrical wire 3 is marked with the dots 7. The encoder 17 is disposed downstream of the pulling rollers 12 and has a pair of rotators 47. When the electrical wire 3 is forwarded in the direction K, the rotators 47 contacting the outer surface 3a of the electrical wire 3 rotate. The number of rotations of the rotators is proportional to a distance of the electrical wire 3 forwarded. The encoder 17 is connected to the control device 19 to output a pulse signal related to the forwarded distance to the control device 19.

When the number of the pulses does not correspond to the forwarded distance of the electrical wire 3, a speed meter can be utilized to compare with the encoder 17.

The cutter 18 is disposed downstream of the encoder 17 to cut the electrical wire 3 with the pair of the blades 48 and

49.

The control device 19 is a computer including a RAM, a ROM, and a CPU and controls the pulling rollers 12, the encoder 17, the cutter 18, and the ink-ejecting unit 15, that is, the entire marking apparatus 1.

The control device 19 stores the pattern of the mark 6 in advance and keeps the pressure of the ink reservoirs 32 at the prescribed level to press the ink. When the control device 19 receives the pulse signal, which is related to the distance forwarded, from the encoder 17, the control device 19 controls the marking nozzles 31 to each eject the droplet of the ink by the prescribed amount toward the electrical wire 3. The control device 19 controls a time interval of ejection of the associated ink according to the pattern of the mark 6 stored in a memory device. The higher the velocity of the movement of the electrical wire 3, the shorter the time interval of ejection, and vice versa.

When the prescribed distance of the electrical wire 3 is forwarded, the pulling rollers 12 stop pulling the electrical wire 3 and allow the blades 48, 49 to cut the electrical wire

3.

The mark 6 on the outer surface 3a of the electrical wire

3 is formed in the manner as described below. The guide roller 11 is attached to the frame 10. The pair of the blades 48, 49 is separated to each other. The electrical wire 3 wound on the guide roller 11 is passed through the correcting unit 13, the stretching unit 14, the ink-ejecting unit 14, the duct 16, and the pulling rollers 12 which hold the electrical wire 3 therebetween . The gas supply unit 33, the gas supply conduits 58, the ink reservoirs 32, the ink supply conduits 59, and the marking nozzles 31 are connected to allow flowing of the ink. The marking nozzles 31 are attached to the unit main body 30 and the associated gas valve 62 is opened. The pulling rollers 12 are driven to pull the electrical wire 3 from the guide roller 11 while the first urging force Hl and the second urging force H2 are applied to the electrical wire 3.

When the control device 19 receives the prescribed pulse signal from the encoder 17, the control device 19 controls the period of the time and the time interval of the current to the coil 40 of the associated marking nozzle 31 so as to eject the droplet of the ink by the prescribed amount toward the outer surface 3a of the electrical wire 3. The outer surface 3a of the electrical wire 3 is dyed with the dye or coated with the pigment. Then, the solvent of the ink adhered on the outer surface 3a of the electrical wire 3 evaporates. The duct 16 evacuates the vapor of the solvent.

The control device 19 stops rotation of the pulling rollers 12 in response to the signal from the encoder 17. The sagging of the electrical wire 3 upstream of the pulling rollers 12 is J- O

stretched by the extensible rod 29 which urges downwardly the electrical wire 3 as shown in the dotted-dashed line (-..-) in FIG. 1.

The pair of the blades 48, 49 approaches each other and cuts the electrical wire 3 and the mark 6 is formed on the outer surface 3a of the electrical wire 3 as shown in FIG. 4.

The marking ink for forming the mark 6 with the dots 7 contains 100 parts by weight of an ink main material and 5-15 parts by weight of ethylene glycol (1, 2-ethanediol) , the ink main material containing the solvent, an acrylic resin, and the coloring material.

The ink main material contains 96 parts by weight of the solvent, 3 parts by weight of the acrylic resin, and 1 part by weight of the coloring material . Ketone (organic solvent) such as acetone or methyl ethyl ketone is utilized for the solvent since the ketone satisfies solubility of the acrylic resin, volatility and handling. Highly volatile alcohol such as methanol or ethanol can be added to the ketone.

The coloring material is selected from the pigment, the dye or a mixture thereof utilized for an ink of an inkjet. The content of the coloring material is adjusted in a concentration with which a clear mark is formed and a suitable ejection is achieved.

When the pigment is utilized for the coloring material, it is necessary that the pigment is uniformly dispersed in the solvent of the acrylic resin and does not clog the second nozzle member 50. The dyes are selected from Oil Yellow 129 (CI Solvent Yellow 29), Oil Yellow 3G (CI Solvent Yellow 16) for yellow, Oil Red 513 (CI Solvent Red 27) , Oil Red RR (CI Solvent Red 24) for red, Oil Blue 2N (CI Solvent Blue 35), Fast Blue 1605 (CI Solvent Blue 38) for blue, and Oil Black HBB (CI Solvent Black 8), Oil Black BS (CI Solvent Black 7) for black. They are commercially available, e.g. from Orient Chemical Industries, LTD.

It is preferable to use the pigment or the mixture with the dye for the outer surface 3a with a deep color and to use the dye for the outer surface 3a with a white or a pale color.

The acrylic resin is selected from PMMA (polymethyl methacrylate) , or PMA (polymethyl acrylate) and a modified PMA, and the combination thereof is also adopted. It is preferable to use the acrylic resin containing a rubber component to achieve toughness of the mark 6. Such acrylic resin is commercially available, e.g. from Asahi Kasei Corporation.

The ink main material may contain a dispersing agent to improve the dispersion of the pigment and a viscosity modifier besides the solvent, the acrylic resin, and the coloring material.

All raw materials described above are mixed, stirred, dissolved, and dispersed together to form the marking ink of the present invention. The viscosity of the marking ink is adjusted so that the marking ink is ejected through the second nozzle members (inner diameter: 0.03-0.1 mm) with the droplet of 10-100 nL. The suitable viscosity and the surface tension of the marking ink are 0.3-2.0 mPa-s and 20-30 mN/m, respectively. It is necessary to contain the coloring material enough to provide a clear visual appearance of the mark 6. The marking ink of the present invention contains 2-10 parts by weight of the ethylene glycol to retard a rate of drying of the marking ink. Accordingly, when the operation is temporally stopped, the ink remained in the second nozzle member 50 of the marking apparatus 1 is not solidified even when the marking ink is exposed to air. The respective second nozzle members 50 are not clogged with the marking inks, so that the marking nozzles 31 are capable of ejecting the marking inks by the prescribed amount.

The marking ink of the present invention is not clogged at the outer end face 50b of the associated second nozzle member 50 shown in FIG. 3, so that the marking nozzle 31 is capable of ejecting the marking ink by the prescribed amount and providing the desirable pattern.

The marking inks each containing 1, 2, 5, 10, 20, 30 parts by weight of the ethylene glycol with respect to 100 parts by weight of the ink main material were prepared and compared with the ink only containing the ink main material about clogging of the nozzle 31 and ejectability. TABLE 1 shows the result.

The ink main material of the experiment of TABLE 1 contained 96 parts by weight of acetone (at least 99 percent purity) as the solvent, 3 parts by weight of the acrylic resin (PMMA) , and 1 part by weight of the oil soluble dye as the coloring material. The ink main material had the viscosity of 0.3-2.0 mPa-s and the surface tension of about 3OmNm. The second nozzle member 50 with the inner diameter of 0.065 mm was utilized for the marking apparatus 1.

TABLE 1

The electrical wire 3 covered with a polypropylene insulation 5, which has an outer diameter of 1.4 mm and a white color, was advanced along its longitudinal direction to form the mark 6 with a thickness of about 10 μm after drying. The ejectability of the ink was evaluated about the second nozzle member 50. Then, the operation of the marking apparatus 1 was quiescence for 4 hours and started again and the clogging of the second nozzle member 50 was evaluated. Good, Fair and Poor about the ejectability indicated in TABLE 1 mean that the amount of the ejection of the ink was enough, that the amount thereof was not enough but the dots were identified, and that the amount thereof was not enough and the dots were not identified, respectively. Good, Fair and Poor about the clogging indicated in TABLE 1 mean that the second nozzle member 50 could eject the ink without washing after the marking apparatus 1 was stopped for 4 hours, that the second nozzle member 50 could eject the ink but the ink could not be ejected perpendicularly to the electrical wire 3, and that the second nozzle member 50 was clogged and the ink could not be ejected, respectively.

TABLE 1 shows that the marking ink containing less than 2 parts by weight of the ethylene glycol caused clogging of the second nozzle member 50. TABLE 1 shows that the marking ink containing more than 10 parts by weight of the ethylene glycol caused the poor ejectability.

The marking ink was evaluated about stability during transportation.

TABLE 2

The marking inks 1-8 of TABLE 2 contained 100 parts by weight of the ink main material and 2 parts by weight of the ethylene glycol. The ink main material contained 96 parts by weight of the acetone (at least 99 percent purity) as the solvent, 3 parts by weight of the acrylic resin (PMMA) , and the oil soluble dye as the coloring material. The resultant ink had the viscosity of 0.3-2.0 mPa-s and the surface tension of about 30 mNm.

The inks 1-8 were received in vessels and kept at temperature between 1-27 degrees C with vibration of ±30 G (acceleration of gravity) . The viscosity and the density of the inks 1-8 prior to and after the test were measured.

TABLE 2 shows that the viscosity and the density of the inks 1-8 were not changed after the test and shows that the inks are stable when the inks are utilized in the factory of marking the electrical wire and the shipment of the marked electrical wire to the assembly factory.

It is appreciated that the embodiment of the present invention is adapted to not only the electrical cable 3 of the motor vehicle but electrical wires used in electronic devices such as portable computer or electrical machines.

It is appreciated that a liquid can be utilized for the pressurized gas supply unit 33. It is appreciated that the marking nozzle 31 can be formed in a tubular or orifice shape in place of the valve unit 38. It is appreciated that the first nozzle member 37 can be integrally formed with the second nozzle member 50.

The embodiments of the present invention are only exemplary but not limited thereto. Any modification or alteration of the embodiments is within the spirit of the scope of the invention.

Industrial Applicability

An addition of 2-10 parts by weight of ethylene glycol to 100 parts by weight of an ink main material moderately delays rate of drying of a marking ink containing the ink main material and the ethylene glycol. Accordingly, when a marking apparatus is temporarily stopped and the marking ink remained in a nozzle is exposed to air, the drying of the marking ink is prevented from solidifying and a clogging of the nozzle is prevented. The nozzle of the marking apparatus assuredly ejects the marking ink in a prescribed direction.

Claims

1. An ink for marking an outer surface of an electrical wire with ejection of a prescribed amount of the ink in a droplet, the ink containing

100 parts by weight of an ink main material, which contains a solvent, an acrylic resin and a coloring material; and 2-10 parts by weight of ethylene glycol.