JPH041708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording material for electrical transfer, and more specifically, a recording material for electrical transfer that is useful for printing records such as noiseless typewriters, computer printing, computer output, and copies of electronic transmission records. Regarding.

As electronic computers and facsimile machines have gradually become more sophisticated, their terminal devices, printers, have also come to occupy an important position. These terminal devices can be broadly divided into impact printers (mechanical printers) and non-impact printers, and the recording methods of the latter include (1) electrophotography, (2) thermal recording, (3) electrical discharge recording, and ( 4) thermal transfer, (5) electrical transfer, etc. are known. However, the former impact printer has a defect in that it is impossible to avoid noise due to its mechanism.

On the other hand, the recording method used in the latter (non-impact printer) is also advantageous in that it does not generate noise, but has various problems. That is,
The electrophotographic method requires five steps of charging, exposure, development, transfer, and cleaning, making the process complicated, and has disadvantages in terms of reliability in consistently obtaining high-quality transferred images and miniaturization of the apparatus. In the heat-sensitive recording method, there are still problems with the storage stability of the heat-sensitive recording material used therein, and the heat-sensitive recording material itself has the disadvantage that it is processed paper and plain paper cannot be used. The discharge recording method is advantageous in that discharge transfer can be performed on plain paper, but it has the disadvantage that odor and burnt residue are generated due to discharge breakdown. In addition, because the thermal transfer method uses a thermal head, it is difficult to obtain high-density images (the limit is about 10 lines/mm), and the recording speed is slow (the limit is about 1 msec/dot). There are drawbacks.

Although it is the same non-impact printer method, it differs from the above method in that the electric transfer method (current transfer recording method) can obtain high-density images on plain paper, has a fast recording speed, and the equipment used in this method is also compact. It has the advantage that it can be used to For this reason, several proposals have been made regarding the current transfer material (recording material for current transfer) used in this method and further improvements to the method.

For example, Japanese Patent Application Laid-Open No. 54-87234 discloses that a coloring material is placed on a conductive substrate, and a coloring material that is soluble in a solvent that does not damage the substrate and has a softening point lower than that of the substrate. An electrically conductive transfer material provided with a transfer layer mainly composed of a plastic polymer resin has been proposed. Here, a polycarbonate resin containing conductive carbon black particles is exemplified as a preferred substrate (ie, base layer). However, although the current transfer material disclosed herein has good abrasion resistance in the transfer layer (i.e., ink layer), there are still drawbacks in the mechanical strength and heat resistance of the base layer.

() Japanese Patent Publication No. 55-12394, Japanese Patent Publication No. 53-7246,
Publications such as JP-A No. 56-8276 and JP-B No. 55-12393 describe two-layer electrical transfer paper in which a conductive ink layer is provided on an anisotropic conductive base layer or a metal-dispersed conductive layer. However, the anisotropic conductive base layer here is high in cost because it is made using special and expensive materials such as metal powder and complicated manufacturing methods. Further, since it is difficult to uniformly disperse the metal powder, there is a drawback that the dot shape becomes distorted and the resolution decreases due to the formation of an inhomogeneous base.

In addition, because the heat resistance and strength of the layer in contact with the electrode needles of many conventional electrical transfer recording materials were not sufficient, they were susceptible to heat damage under conditions (high applied voltage - current) that produced sufficient dot density. The stylus got dirty easily. On the other hand, if the sheet is made to have high heat resistance, the sheet will be easily torn due to insufficient flexibility, making it difficult to scan the electrode needles smoothly. Furthermore, recording materials with a multi-layer structure have the disadvantage that part of the base layer is transferred along with the transferred ink, resulting in uneven dot density and uneven dot shape, resulting in slightly inferior dot quality compared to single-layer types. Ta.

In addition, as mentioned above, in the case of conventional recording materials for electrical transfer, the strength of the layer in contact with the electrode needles was not sufficient, so considerable care must be taken when handling them during manufacturing, cartridge resetting, transportation, etc. The reality is that this is necessary.

An object of the present invention is to provide a recording material for electrical transfer that can provide sufficient dot density and has excellent dot quality, mechanical strength, durability, and heat resistance. Another object of the present invention is to provide a recording material for electrical transfer that is easy to handle.

That is, in the present invention, a recording body and a recording material for electrical transfer are placed one on top of the other, a return electrode is brought into contact with the recording material, and a recording electrode needle is brought into contact with the surface of the recording material, and a voltage is applied to energize the recording material. , the recording material used in the current transfer recording method in which ink is transferred onto the recording body has a two-layer structure consisting of a base layer and an ink layer from the recording electrode side, or a three-layer structure consisting of a base layer, an intermediate layer and an ink layer. structure, and the base layer has the general formula −NH−Ar ₁ −
It is characterized by containing NHCO-Ar ₂ -CO- (wherein Ar ₁ and Ar ₂ are divalent aromatic groups which may be the same or different) (hereinafter referred to as aromatic polyamide) and carbon black as the main components. .

Hereinafter, the present invention will be explained in more detail based on the accompanying drawings. FIG. 1 is a sectional view of a recording material 1 of the present invention having a two-layer structure of a base layer B11 and an ink layer I13, and FIG. FIG. 2 is a cross-sectional view of material 1'. Here, the intermediate layer 12 is provided as necessary.

The main functions required for each layer are (a) Base layer 11
The type that generates Joule heat in (b) the ink layer 13 and the type that generates Joule heat in the ink layer 13 are different in terms of electrical resistance R, but both types have the following in common: The base layer 11 on the electrode needle side must have high heat resistance to prevent heat damage and stylus staining, and the ink layer 13 has a low softening point. In the recording material of the type (b) above in which the intermediate layer 12 is provided, the intermediate layer 12 generates more heat than the base layer 11 and the ink layer 13, and therefore, in this case, The intermediate layer 12 is formed of at least a flexible film layer. Providing the intermediate layer 12 is advantageous in various respects, which will be more fully understood from the following description.

In order to fully exhibit the above-mentioned functions, the electrical resistance R of each layer in the recording material shown in FIG.
For type (b), it is necessary to set R _I > R _B , and for type (b) above, R _B > R _I
It is necessary to do so. On the other hand, in the recording material shown in Fig. 2, the electrical resistance R of each layer must be set to R _M ≧ R _I > R _B or R _I > R _M > R _B for the type (a) above. , Regarding the type (b) above,
It is necessary to satisfy R _M ≧ R _B > R _I or R _B > R _M > R _I.

Due to this relationship, especially in the recording material shown in FIG. This reduces heat generation in the base layer 11, solving problems such as damage to the base layer 11 due to heat and dirt on the stylus, and also reduces contact resistance with the stylus, reducing dot dropouts and the like. Since the current flows concentratedly in the ink layer 13 immediately below the stylus, the dot remains sharp, and other effects are brought about.

Further, if a material that is easily separated from the base layer 11 is used for the intermediate layer, it becomes possible to obtain a more desirable recording material. That is, as shown in FIG. 3, when the heat generated by the current from the stylus 6 is concentrated directly below the stylus 6, only the portion of the intermediate peeling layer 12' where the heat is concentrated is peeled off from the base layer 11 and together with the ink layer 13. Transferred to recording body 2. This makes it possible to achieve sharp dot quality and uniform density.

The materials forming each layer are as follows.

Of course, the base layer 11 is required to have high heat resistance, and as mentioned earlier, it is necessary to improve the mechanical strength, particularly the tear strength and heat resistance of the recording material (ink sheet, ink ribbon), and to It facilitates handling during ribbon manufacturing, cartridge loading, transportation, etc., and furthermore,
In order to minimize damage to the surface of the base layer due to electrical conduction, the present invention particularly uses a sheet-like material whose main components are aromatic polyamide as a binder and carbon black as a conductive agent. Here, the ratio of aromatic polyamide to carbon black is 70 to 70 for the former by weight.
97%, the latter 3 to 30% is appropriate.

For aromatic polyamides, for example, JP-A-53-
Those described in Japanese Patent No. 35797 can be used. Specifically, poly(m-phenylene isophthalamide), poly(m-phenylene terephthalamide), poly(p-phenylene isophthalamide), poly(p-phenylene terephthalamide),
are cited as representative examples. Among them, poly(m-phenylene isophthalamide), poly(m-
Phenylene terephthalamide) is useful when forming a film using a wet method (casting method) because it is soluble in many solvents and can be dissolved at a high concentration. Dimethylacetamide, N-
Methyl-2-pyrrolidone and the like are preferred.

In any case, the above aromatic polyamides may be used alone or in combination of two or more. Further, it is desirable that the softening point of the resin binder component (aromatic polyamide) forming these base layers 11 is 180° C. or higher.

The intermediate layer 12 or intermediate release layer 12' has a softening point of 150
Resins with temperatures above ℃ are suitable. If a resin with a softening point lower than 150°C is used, the film-forming ability will be low, and the sheet will not be strong enough and will soften or melt due to the heat generated when electricity is applied, making it difficult to function as a film-forming layer. become unable.

Examples of resins that can be used for the intermediate layer 12 include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, and vinyl chloride-vinyl acetate copolymer.
Vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, acrylic ester-styrene copolymer, methacrylic ester-acrylonitrile copolymer , methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, urethane elastomer, nylon-silicon resin, nitrocellulose-polyamide resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene- Acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cellulose diacetate,
cellulose triacetate, cellulose propionate, nitrocellulose, etc.), polycarbonate, styrene-butadiene copolymer, polyester resin, chlorovinyl ether-acrylic acid ester copolymer, amino resin, various rubber-based thermoplastic resins, and these It is a mixture of etc. Other materials include cellulose acetate with a plasticizer added, polycarbonate, uncured polyester (solution type), polyvinyl alcohol, nylon, styrene-butadiene copolymer (low styrene type),
Styrene-acrylic copolymers, styrene with a plasticizer added, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, and these with a plasticizer added are preferable.

Examples of flexibility imparting agents include phthalate esters, phosphate esters, fatty acid esters, glycols,
There are oils and fats.

Further, for the intermediate release layer 12', a resin having a release effect is selected for the purpose of aiding ink transfer, and therefore, resins such as silicone resin, methyl methacrylate, polyethylene, polypropylene, fluorine-containing polymer, polyvinyl alcohol, polyester are selected. In addition to cellulose resins (for cellulose), binders containing carbonates of inorganic oxides such as silicon oxide and magnesium carbonate, and chlorinated rubber, commercially available release agents (trade name Chiron C: myristic acid chromic chloride) ) etc. can be used.

The intermediate layer 12 (including the intermediate release layer 12')
, it is preferable to use a relatively high resistance (10 ⁴ to 10 ⁶ Ω) to generate heat more efficiently, and a relatively low resistance (10 ⁰ to 10 ^{3 Ω} ) to make the dots sharp. Ω) is preferable.

On the other hand, as the resin forming the ink layer 13,
Softening point or melting point is 50-200℃, preferably 60-120℃
℃, such as low-molecular polystyrene, styrene-butyl methacrylate copolymer, and low-molecular polyamide, and in addition to these, waxes such as carnauba wax, oils and fats such as linseed oil, and various modified rosins. It is better to add something like Since the ink layer 13 has the role of carrying out electricity faithfully to the shape (diameter and round shape) of the electrode needle, and at the same time melting with low energy and transferring to the recording medium 2, the resin used therein should be within the above range. It is necessary to have a certain softening point or melting point. If the softening point or melting point is lower than 50℃, scumming will occur during transportation or pressure welding;
If the temperature is higher than ℃, the ink will melt with low energy and will not form a good heat transfer ink.

Further, a coloring component is added and dispersed in the ink layer 13, and this coloring component (coloring pigment, coloring dye)
constitutes a thermal transfer ink together with a portion of the resin (binder) present around it.
In addition to carbon black (particularly furnace-type carbon black, acetylene black, lamp black, etc.), these coloring components include phthalocyanine, alkali blue, spirit black, benzidine yellow, first-strength, and crystal coloring organic or inorganic dyes and pigments. Examples include violet, iron oxide, and cadmium sulfide.

When producing the recording material of the present invention, the base layer 11 and the ink layer 13 or the base layer 1
1. In order to make the electrical resistances of the intermediate layer 12 (including the intermediate peeling layer 12') and the ink layer 13 conform to the above relationship, appropriate amounts of various organic or inorganic conductive materials are added to each of the above layers. . Examples of such conductive materials include conductive carbon black (which is also ideal as a coloring component), ordinary carbon black, graphite,
A typical example is oil black.

In order to actually produce the recording material of the present invention, it is sufficient to disperse or dissolve the materials necessary for each layer in an appropriate solvent and apply and dry them one after another on a glass plate, metal plate, etc. After forming the layer 13 to have a thickness of 1 to 10 μm, preferably 2 to 4 μm, the intermediate layer 12 to a thickness of 5 to 20 μm, preferably 5 to 10 μm, and the base layer 11 to a thickness of 0.5 to 10 μm, preferably 3 to 5 μm, a glass plate, a metal plate, etc. Just peel it off. When providing the intermediate peeling layer 12' with peelability, the film thickness is the same as above for the ink layer 13, and the thickness of the intermediate peeling layer 1
2' is 0.5 to 5 μm, preferably 1 to 3 μm, base layer 1
1 is 5 to 20 μm, preferably 5 to 10 μm.

Further, as the solvent, dimethylformamide, dimethylacetamide, N-
In addition to methyl-2-pyrrolidone, examples include tetrahydrofuran, 1,2-dichloroethane, methyl ethyl ketone, toluene, petroleum ether, ethyl acetate, dimethylformamide, and methanol.

In order to carry out current transfer recording using the recording material for current transfer produced in this way, the ink layer 13 is brought into close contact with the recording body 2, and the intermediate layer 12 (or , intermediate release layer 1
The return electrode 4 is brought into contact with the base layer 11 via the base layer 2'), and the current signal from the recording applied voltage 5 is applied to the base layer 11 through the recording needle 3 to generate the recording current 6 indicated by the arrow. (However, in the case of (b) above).

When the recording material 1' is energized, the current density directly below the recording needle is maximum and the return electrode 4 has a larger contact area than the recording needle 3.
As it approaches , the current spreads and the current density becomes smaller. The ink is softened or melted by the Joule heat generated by this energization and transferred to the recording medium 2. Here, an image corresponding to the current signal is formed on the recording medium 2.

Current conditions, number of scanning lines, etc. greatly affect image formation, but generally 10 to 200V and 0.05V for energization time.
~1 msec, and the number of scanning lines is approximately 3 to 20 lines/mm. The recording material 1' and the recording medium 2 are brought into complete contact with each other. Since the recording material of the present invention does not transfer all of the colored components onto the recording medium 2 even when a relatively strong current is applied, it can be used repeatedly.

Although the above-described current transfer recording method is explained based on the recording material 1' shown in FIG. 2, the same applies to the recording material 1 shown in FIG.

As described above, by using the recording material of the present invention, a high quality image can be quickly formed on a recording medium such as plain paper with low recording energy. This is because the recording material has a two-layer structure consisting of a base layer and an ink layer, or a three-layer structure consisting of a base layer, an intermediate layer, and an ink layer, and the functions of each layer are separated, and preferably the intermediate layer is made of a removable material. It has become clear that excellent image quality can be obtained by using an intermediate release layer.

Furthermore, the base layer in the recording material of the present invention has a completely different structure from the conventional special and expensive anisotropically conductive base layer, and can simply be a uniformly dispersed layer containing a conductive material. Since it is more uniform than the anisotropically conductive base layer, it has the effect of allowing high-quality dot recording that is faithful to the shape of the recording needle.

In addition, in the recording material of the present invention, by increasing the mechanical strength (particularly tear strength) and heat resistance of the base layer, even better quality and sharp dot recording can be obtained with high reliability.

Next, examples and comparative examples will be shown. Note that all parts are parts by weight.

Example 1 A mixture consisting of 9 parts of poly(m-phenylene terephthalamide), 9 parts of carbon black (manufactured by Nippon EC Co., Ltd.), 1 part of calcium chloride, 5 parts of N-methyl-2-pyrrolidone, and 85 parts was dispersed in a ball mill for 120 hours. The material was cast onto a glass plate using a blade with a gap of 200 μm, dried in a dryer at 110°C for 1 hour, and then immersed in cold water at about 5°C for 1 minute to peel it off from the glass plate. Next, after washing in running water at about 20°C, in a wet state, it was stretched twice in each direction, lengthwise and horizontally, and then heat-treated at 300°C for 10 minutes to form a film with a thickness of about 20μm and an electrical resistance.
A base layer sheet of 60KΩ was obtained. Next, a mixture consisting of 85 parts of oligostyrene (softening point 65°C), 15 parts of carbon black (manufactured by Nippon EC Co., Ltd.), and 900 parts of cyclohexane was dispersed on top of this using a ball mill for 24 hours, and a blade with a gap of 100 μm was dispersed thereon. Apply it using a hair dryer, dry it for 1 minute at 100℃,
An ink layer with a thickness of about 5 μm was formed.

The electrical resistance of the entire ink sheet (recording material for electrical transfer) made in this way is 5KΩ,
In addition, the mechanical strength of this product is tensile strength 1200
It was confirmed that the film had sufficient strength with a tear strength of 150 g/20 μm and a tear strength of 150 g/20 μm.

Recording was performed on this ink sheet using a multi-stylus in which recording electrodes with a diameter of about 60 μm were arranged in two rows in a staggered manner at a density of 8 electrodes/mm under conditions of a signal voltage of 150 V and an application time of 0.1 msec. , clear and high-density characters with a high resolution of 16 dots/mm and a dot density of 1.4 were obtained on plain paper (recording material).

Further, even when 10,000 characters were repeatedly recorded using this ink sheet, no adhesion was observed on the surface of the multi-stylus. this is,
It is thought that the heat deformation temperature of the base layer in this ink sheet was as high as 250 to 300°C, and as a result, the base layer did not adhere due to heat.

Example 2 A mixture consisting of 88 parts of poly(m-phenylene isophthalamide, 9 parts carbon black (manufactured by Nippon EC Co., Ltd.), 1 part calcium chloride, 2 parts dimethylacetamide) was used as the material for the base layer sheet. An ink sheet was prepared in the same manner as in Example 1. However, here, the base layer sheet had a thickness of about 15 μm, an electrical resistance of 100 KΩ,
The thickness of the ink layer was approximately 3 μm, and the electrical resistance of the entire ink sheet was 10 KΩ.

Next, this ink sheet was slit to a width of 6.35 mm, stored in a cartridge, and recorded under the same conditions as in Example 1, resulting in 16 dots/mm on plain paper.
Clear and high-density characters with a dot density of 1.2 were obtained with a high resolution of .

Furthermore, this character quality remained the same even when 10,000 characters were repeatedly recorded. This is considered to be due to the high thermal deformation temperature of the base layer, as described in Example 1. The mechanical strength of this slit ink ribbon was 950 g/15 μm in tensile strength and 180 g/15 μm in tear strength.

Comparative Example 1 A mixture consisting of 93 parts of cellulose triacetate, 7 parts of carbon black (manufactured by Nippon EC Co., Ltd.) and 1400 parts of methylene chloride was dispersed in a ball mill for 24 hours, and then spread on a polyester film with a gap of 300 μm.
Cast coating on a plate of 70 m and dried with a dryer
Dry at ℃ for 1 minute, electrical resistance 100KΩ, thickness approx.
A base layer of 15 μm was formed. Next, an ink layer (with a thickness of approximately 3 μm) was formed on this base layer in the same manner as in Example 1, and then the base layer and ink layer were integrally peeled off from the polyester film to obtain an ink sheet. Obtained. The electrical resistance of the entire ink sheet in this comparison was 5KΩ.

Subsequently, when this ink sheet was used to record under the same conditions as in Example 1, sharp characters with a dot density of 1.2 were obtained on plain paper. Also, the heat distortion temperature of the base layer in this ink sheet is
Since the temperature was approximately 180°C, some stains on the multi-stylus were observed, but the above-mentioned character quality was maintained until 10,000 characters were repeatedly recorded.

However, the mechanical strength of this ink sheet is tensile strength of 500 g/15 μm and tear strength of 20 g/15 μm.
It was confirmed that the ink ribbon was weak at 15 μm and was often cut when it was slit into a ribbon with a width of 6.35 mm, and the ink ribbon was often cut during recording in the cartridge.

Comparative Example 2 A mixture consisting of 9 parts polycarbonate, 1 part carbon black (manufactured by Nippon EC Co., Ltd.) and 100 parts of 1,2-dichloroethane was dispersed in a ball mill for 24 hours. A comparative ink sheet was prepared in the same manner as in Example 1. However, here the base layer is approximately 15μ thick.
m, electrical resistance is 50KΩ, and the ink layer is approximately 3μ thick.
m, and the electrical resistance of the entire ink sheet was set to 4KΩ.

Next, this ink sheet was slit to a width of 6.35 mm, stored in a cartridge, and printed under the same conditions as in Example 1. At the beginning, relatively sharp characters with a dot density of 1.1 to 1.2 were obtained on plain paper. However, when recording 100 to 1000 characters repeatedly, it was observed that the dot density decreased to 0.5 to 1.0.

When the surface of the multi-stylus was observed after repeated recording, it was found that the base layer had adhered there due to heat. This means that the heat distortion temperature of the base layer is approximately 120
This is thought to have occurred due to the low temperature.

Example 3 A solution consisting of 95 parts of silicone resin, 5 parts of ketten black, and 900 parts of xylene was applied onto the same base layer as in Example 2 (thickness: about 15 μm, electrical resistance: 100 KΩ) using a blade with a gap of 50 μm. It was dried for minutes to form an intermediate layer about 2 μm thick. Furthermore, a liquid consisting of 80 parts of low-molecular styrene, 20 parts of styrene black, and 900 parts of cyclohexane is applied onto this intermediate layer using a blade with a gap of 100 μm, and dried at 70°C for 1 minute to form an ink layer approximately 3 μm thick. I created a sheet. Incidentally, the electrical resistance of this ink sheet as a whole was 9KΩ.

Next, this ink sheet was applied with a signal voltage of 100 V and an application time of 0.1 m using the same device used in Example 1.
When recording was performed under conditions of sec, sharp characters with a dot density of 1.5 were recorded on plain paper (recording material). Furthermore, similar printing quality was obtained even after 10,000 characters were repeatedly recorded using this ink sheet.

In the case of this ink sheet, although it has not been confirmed through testing, it is presumed that the main part of the heat generated by electricity is generated by the intermediate layer (see Figure 4). It is thought that it is possible to record more characters repeatedly than what was described.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of two examples of recording materials according to the present invention, and FIGS. 3 and 4 are diagrams showing an outline of recording. 1, 1'...Recording material for electrical transfer, 2...Recording body, 3...Stylus, 4...Return electrode, 5...
Recording applied voltage, 6... Recording current, 11... Base layer, 12... Intermediate layer, 12'... Intermediate release layer, 1
3...Ink layer.

Claims (1)

[Claims] 1 A recording body and a recording material for electrical transfer are placed one on top of the other, a return electrode is brought into contact with the recording material, a recording electrode needle is brought into contact with the surface of the recording material, and a voltage is applied to the recording material to energize the recording material. The recording material used in the current transfer recording method for transferring onto a recording medium has a double structure consisting of a base layer and an ink layer from the recording electrode side, or a three-layer structure consisting of a base layer, an intermediate layer and an ink layer, And the base layer has the general formula −NH−Ar ₁ −NHCO−Ar ₂ −CO−
(However, Ar ₁ and Ar ₂ may be the same or different divalent aromatic groups) and carbon black as main components.