JPH075756B2 - Conductive film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a conductive film, and more particularly to a noiseless typewriter, a computer computer printout, a computer computer output printout or a copy transmission record, and the like. The present invention relates to a useful electrotransfer recording material, a jacket such as a floppy disc or a compact disc, and a conductive film used for a bag or the like when storing or transporting IC or LSI.

[Conventional technology]

In recent years, thermal transfer recording has been attracting attention in the fields of electronic calculators, facsimile machines, etc., because it is non-impact, noiseless, low cost, and can be made compact and lightweight.Especially, the method of conducting thermal transfer by means of a current-carrying head is an effective hard copy. This is the most promising method.

In general, the electric current transfer recording method is performed by pressing the electric current head composed of the electric current recording electrode and the return electrode to the electric current transfer recording material composed of the resistance layer, the conductive layer, the ink layer, and the like to heat the resistance layer to heat it up. Then, heat is transferred to the conductive layer, the temperature of the ink layer rises, and the ink layer melts and flows, so that transfer recording is performed on the recording material.

In such an energization transfer recording method, it is important to properly set the resistance value of the resistance layer because the resistance layer generates heat when energized. Conventionally, a metal material such as copper, iron or aluminum is dispersed in a resin to form a sheet or A method of forming a film-like resistance layer (hereinafter referred to as a resistance layer) or a method of forming a resistance layer by dispersing graphite and acetylene black in a resin (Japanese Patent Publication No. 56-27382) or DBP.
A method in which a carbon black with an oil absorption of 300 ml / 100 g or more is dispersed in a resin solution and a resistance layer is formed by a solution casting method (JP-A-60-71293). Further, the carbon black is dispersed in a resin and melt-pressed. A method of forming a resistance layer by a method (Japanese Patent Laid-Open No. 59-120494) has also been known.

[Problems to be solved by the invention]

However, in the resistance layer formed by the conventional method, for example, when metal powder is used, it is difficult to uniformly disperse the metal powder, so the transfer recording performance is deteriorated, and when graphite is used, the surface resistance value is reduced. It is difficult to lower the value to a practical value, and it is possible to lower the surface resistance layer when using a carbon black with a DBP oil absorption of 300 ml / 100 g or more. In order to form the resistance layer by the method, a device for coating the resin solution, solvent drying, recovery, etc. is required, and the device itself becomes complicated, and in the method of forming the resistance layer by the melt extrusion method, the surface of the obtained resistance layer is Since the resistance value and the specific resistance value are very high, the applied voltage is also high, and there is a problem with the moldability as well, and it has not been put to practical use. In any case, the moldability is good and the resistance is low. Value of conductive film Development was desired.

[Means for solving problems]

Therefore, the inventors of the present invention have conducted extensive studies to solve the conventional problems, and as a result, have further studied by paying attention to forming a conductive film by a melt extrusion method that is simple in terms of equipment, It is possible to sufficiently reduce the surface resistance value and the specific resistance value of the conductive film by using the carbon black having a specific physical property as a component that imparts conductivity to the conductive film. The present invention has been completed by finding that a film can be obtained.

That is, it is an object of the present invention to provide a conductive film having high characteristics, particularly a conductive film which can be sufficiently used at a low applied voltage and has a high performance and which has excellent durability. Then, the purpose is composed of a carbon black and a thermoplastic resin, in a conductive film obtained by the melt extrusion method, the film has a pore volume of 2.5cc / g or less by the mercury porosimeter method, also mercury porosimeter method It is easily achieved by the conductive film characterized by the carbon black obtained by the furnace method with the maximum peak position of the pore distribution of 200 Å or more and the DBP oil absorption of 20 to 250 ml / 100 g and the thermoplastic resin. It

Hereinafter, the present invention will be described in detail.

The carbon black used in the present invention is a carbon black obtained by the furnace method, the pore volume by the mercury porosimeter method is 2.5 cc / g or less, and the maximum peak position of the pore distribution is 200 Å or more, preferably 300 Å or more. It has a physical property of DBP oil absorption of 20 to 250 ml / 100 g.

Specifically, "E-UHS", "# 30B", "APF", "# 10"
A furnace carbon black such as B ","# 5B "(manufactured by Mitsubishi Kasei Co., Ltd.) is used. Further, the thermoplastic resin of the present invention is a resin which has been conventionally used in the field of information equipment such as thermal transfer recording. It is not particularly limited as long as it is, polyethylene terephthalate, polystyrene, polyvinyl chloride, polycarbonate, nylon, polyethylene, polypropylene and the like are used, in particular, nylon,
Polypropylene, polycarbonate and polyethylene terephthalate are preferable in terms of heat resistance and durability.

20 to 200 parts by weight, preferably 30 to 150 parts by weight, of the carbon black specified in the present invention is added to the thermoplastic resin per 100 parts by weight of the resin. If necessary, an appropriate amount of additives such as a dispersant, a softening agent and a lubricant may be added.

The conductive film of the present invention has a thickness obtained by melt-extrusion after heating and uniformly mixing the above carbon black and thermoplastic resin.
It is obtained by forming a film having a thickness of 30 μm or less.

The melt extrusion method is not particularly limited as long as it is a generally known method, and specifically, a method of extruding a flat film from a T-type die (T die method),
Examples include a method of extruding compressed gas at the same time as extruding from a ring-shaped circular die to form a tube-shaped film (inflation method), or a stretching method of stretching the film obtained by these methods.

The electroconductive film of the present invention obtained as described above is used for various purposes. In particular, a conductive transfer recording material formed by laminating an electroconductive layer and an ink layer or an electroconductive layer, a peeling layer, an ink layer and the like. Used as a resistance layer for the.

For example, in the case of producing a current transfer recording material consisting of a resistance layer, a conductive layer, and an ink, after forming the resistance layer made of a conductive film as described above, a conductive layer such as aluminum having good conductivity is formed as the conductive layer. A thin film of a substance is formed on the resistance layer by a vapor deposition method or the like. Then, the ink layer is applied onto the conductive layer on the side opposite to the resistance layer by a hot melt method or a solution method.

The ink layer is not particularly limited as long as it is used in a known thermal transfer recording material, for example, paraffin wax, modified wax, carnauba wax, etc., about 60% by weight wax, coloring material pigment or About 20% by weight of dye,
It is advisable to make up about 20% by weight of resin.

Each layer is formed as described above. The thickness of each layer is as follows: ink layer; conductive layer; resistance layer 1 to 10 μm; 0.01 to 0.2 μm; 30 μm
The thickness is preferably 2-5 μm; 0.05-0.1 μm; 20 μm or less.

A peeling layer such as polyketone may be provided between the ink layer and the conductive layer in order to improve the peeling between the ink layer and the conductive layer.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Polypropylene “Novatec” -P-4100Y (Mitsubishi Kasei Kogyo Co., Ltd., MI; 1.2 g / 10 minutes) 1.4 kg and 0.6 kg carbon black having the physical properties shown in Table 2 have an internal volume of about 9
Insert it into the Hensiel mixer at 1
Mix for minutes.

The obtained mixture was allowed to stand in a vacuum dryer heated to 120 ° C., dried for 12 hours, and then kneaded with a biaxial kneader to obtain a chip-shaped compound. This compound in a vacuum dryer
Dry at 120 ℃ for 24 hours, then single screw extruder (30φ, 4D
= 22) to produce a conductive film under the conditions shown in Table 1. The physical properties of the obtained film are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 3 Except that the mixing ratio and the brand name of the carbon black when mixing the polypropylene and the carbon black of Example 1 with a Henschel mixer were changed as shown in Table 1.
A conductive film was produced in the same manner as in Example-1. The physical properties of the carbon black used here are as shown in Table 2.

Reference Example Aluminum was vapor-deposited on the film obtained in Example-1 to a thickness of 0.08 μm using a commercially available vacuum vapor deposition apparatus.

Then, an ink having the following composition was applied on the vapor deposition surface to a thickness of 4 μm.

Ink composition and production method Carbon black ……………… 15 parts (Mitsubishi Chemical Co., Ltd. “MA-8”) Paraffin wax ………… 25 parts Oxidation wax ………… 40 parts Ethylene / vinyl acetate co-weight Combined ... 20 parts ("TM-PEV-720" manufactured by Hoechst) The above mixture was premixed with a mixer and then kneaded 5 times with a 6-inch three-roll mill. 3μ in this innki
None of the above carbon black aggregates were present. The finished ribbon was printed on plain paper under the conditions of applied voltage of 12 V, pulse frequency of 100 Hz, pulse width of 2 ms and paper feed speed of 16 mm / s. As a result, clear and unblurred characters were recorded.

Prints using this ribbon have been found to be superior to commercially available ribbons for similar purposes.

In addition, since the resistance of the resistance layer made of a conductive film was as low as about 10 ohms, the applied voltage for driving could be 12 V and printing could be performed at an extremely low voltage.

Evaluation methods of various physical properties Among the physical properties of carbon black, the DBP oil absorption is JIS-K-6221.
-A method was used.

The pore volume and the maximum peak position of the pores were measured by the mercury intrusion method in the pore radius range of 75 to 75000Å. (The equipment used is Micrometrics Instrument (Micr
omeritics Instrument's "Auto Pore"("A
uto Pore ")-9200) MI of the compound was measured by using a melt indexer manufactured by Takara Kogyo Co., Ltd. under the conditions of a temperature of 230 ° C and a load of 11 kg.

The film resistance was measured using an apparatus as shown in FIG.

That is, a stock film piece 1 having a diameter of 30 mm or more is sandwiched between electrodes having a diameter of 25 mm [2; upper electrode (1100 g) "2"; lower electrode], and 1.
The resistance after 30 seconds with a load of 0 kg applied is measured with a resistance meter 4 ["Digital Multimeter TR-6856" (manufactured by Takeda Riken)]
It was measured at.

The film moldability is 10 cm ^{2 of} film extruded by T-die.
Thickness is measured at more than 30 places using a commercially available dial thickness gauge (measurement can be made to a minimum of 1 μm), and the thickness variation is 10% or less relative to the average thickness, ○, 10 to 20% △, 20% or more It was evaluated as x.

[Effects of the Invention] According to the present invention, a conductive film having good moldability and capable of sufficiently generating heat at a low voltage can be easily obtained, and the conductive film of the present invention is particularly suitable at a low applied voltage. It is suitable as an electrically conductive transfer recording material having excellent durability that can be used for.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a film resistance measuring device used for measuring a resistance value of a conductive film according to the present invention. 1; Sample film piece, 2, 2 '; Electrode, 3; Load, 4; Resistance meter

Claims (5)

[Claims] 1. A conductive film comprising a carbon black and a thermoplastic resin, obtained by a melt extrusion method, wherein the film has a pore volume of 2.5 cc / g or less measured by a mercury porosimeter method, and a mercury porosimeter method. The maximum peak position of the pore distribution is 200Å or more, and DBP
A conductive film comprising a carbon black obtained by the furnace method with an oil absorption of 20 to 250 ml / 100 g and a thermoplastic resin. 2. The conductive film according to claim 1, wherein the film has a thickness of 30 μm or less. 3. The conductive film according to claim 1, wherein the conductive film contains 20 to 200 parts by weight of carbon black based on 100 parts by weight of the thermoplastic resin. 4. The conductive film according to claim 1, wherein the thermoplastic resin is polypropylene, nylon, polycarbonate or polyethylene terephthalate. 5. The carbon black has a pore volume of 2.5 cc / g or less by the mercury porosimeter method, the maximum peak position of the pore distribution by the mercury porosimeter method is 300 Å or more, and DBP.
The conductive film according to claim 1, which has an oil absorption of 20 to 250 ml / 100 g.