JPH042061Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical field] This invention relates to a thermal transfer typewriter ribbon. [Background Art] A thermal transfer type writer ribbon has a thermal transfer layer consisting of an ink layer that melts when heated by a thermal head on one side of a strip-shaped film serving as a base, and is used in a typewriter with a thermal head type heating printing means. It is something. In this typewriter, a ribbon is sandwiched between the heating printing means and the typing paper with the thermal transfer layer facing the typing paper, and the heating printing means heats the thermal transfer layer of the ribbon to apply ink in the shape of a predetermined printed image. The ink is melted and transferred onto type paper to form a printed image on the paper. The temperature of the heating printing means is usually 100 to 500°C. Conventional ribbons have had a problem in that when characters with a large number of strokes, such as Chinese characters, are typed onto paper, the clarity of the typed characters deteriorates. In addition, in order to make the cartridge that houses the ribbon more compact and to make the ribbon longer, it is being considered to make the ribbon film thinner. As a result, it has become difficult to make the cartridge more compact. [Purpose of the invention] This invention was made in view of the above circumstances, and it is possible to type characters with a large number of strokes clearly on any type paper, and it is easy to run even if it is thin. Our goal is to provide superior typewriter ribbons. [Disclosure of the invention] In order to achieve the above object, this invention provides a thermal transfer layer consisting of an ink layer that is melted by heating with a thermal head on one side of a strip-shaped film serving as a base, and enables thermal printing using a thermal head. In the typewriter ribbon used in the typewriter of the present invention, the substrate is a biaxially stretched polypropylene film, and a heat-resistant resin layer is provided on one side of the substrate.
The ink layer is provided on the other side, and the total thickness of the biaxially stretched polypropylene film and the heat-resistant resin layer is 3.
~16μ, the surface roughness Ra of the ink layer side surface of the polypropylene film is 0.2μ or less, and the surface roughness Ra of the exposed surface of the heat-resistant resin layer is 0.07~
The gist is typewriter ribbon, which is 1.5μ.
Hereinafter, this invention will be explained in detail based on drawings showing embodiments. 1 and 2 both show a typewriter ribbon according to this invention. As shown in both figures, the typewriter ribbons 1 and 1' according to this invention both have a biaxially stretched polypropylene film 2 as a base, a heat-resistant resin layer 3 is provided on one side, and a heat-resistant resin layer 3 is provided on the other side. An ink layer (thermal transfer layer) 4 which is melted by heat transfer is provided. The surface roughness Ra of the ink layer side surface 2a of the polypropylene film 2 is 0.2μ or less, and the heat-resistant resin layer 3
The surface roughness Ra of the exposed surface 3a is 0.07 to 1.5μ. Here, biaxially oriented polypropylene (hereinafter referred to as
A film (abbreviated as OPP) is a biaxially stretched film that is stretched by a well-known stretching method such as simultaneous biaxial or sequential biaxial stretching, and is a film in which 50% by weight or more of the film is made of polypropylene. As the polypropylene, a commonly used polypropylene homopolymer can be used, and as other resins to be mixed, α-olefin homopolymers and copolymers represented by ethylene and butene-1 can be used. Polymers and the like can be preferably used. In this invention, the surface roughness Ra of the laminated film surface on the side where the ink layer is provided is as described above.
It is necessary to make it 0.2μ or less, preferably
The thickness should be 0.1μ or less. Here, the surface roughness
Ra is center line average roughness (cutoff value 0.25mm)
It is based on JIS B 0601. In this way, by providing an ink layer on a surface with particularly small surface irregularities, that is, a smooth surface, the clarity of characters during typing can be greatly improved. On the other hand, if the surface roughness Ra of the surface on which the ink layer is provided exceeds 0.2 μ, the clarity of typed characters deteriorates, and characters are likely to be cut off, fluffed, etc. In addition, as a base film,
Because OPP film is used, which is strong, has little elongation, is flexible, and has low elasticity, the ribbon is not affected by the smoothness (surface roughness) of the type paper surface.
It can always follow the unevenness of the paper surface, improving the adhesion of the ink layer, so that characters are always typed clearly, and the clarity of the characters remains unchanged no matter what type of paper is used. This is what happens. The thickness of the OPP film is preferably 2-15μ, more preferably 3-10μ. Here, the thickness of the OPP film is defined as the thickness of the OPP film when the cross section is viewed under a microscope and as shown in Figure 1, if both sides of the OPP film appear smooth, the smooth surface 2a
The thickness from the smooth surface 2a to the other smooth surface t ₁ , as shown in FIG. 2, when unevenness is visible on the surface on the heat-resistant resin layer side, the thickness t ₂ was measured at five locations each, the average value was determined, and this was taken as the thickness. The types of additives that are commonly known to be added to OPP films (thermal stabilizers, antioxidants,
Nucleating agents, antistatic agents, lubricants, weathering agents, etc.) may be added to the extent that they do not impair the properties of this invention. In this invention, since a biaxially stretched film is used as the base, the film can be made strong and with little elongation. Further, the mechanical properties and shrinkage properties in the length direction and width direction are well balanced, and the film can be made into a film with little thickness unevenness. Therefore, a ribbon with excellent performance can be obtained. The heat-resistant resin layer laminated to the OPP film is
Melting point is preferably 170℃ or higher, more preferably 200℃
It is sufficient if it is made of resin with a temperature of at least 0.degree. C. and does not cause sticking with the thermal head. Specific resins include, for example, poly-4-methylpentene-1, blends of poly-4-methylpentene-1 and other α-olefins, epoxy resins,
Examples include polyester resin, polyamide, polyimide, polysulfone, polycarbonate, and the like.
In the case of a blend of poly-4-methylpentene-1 and other α-olefins, the proportion of poly-4-methylpentene-1 is preferably 60% by weight or more, and preferably 80% by weight or more. is more preferable. The thickness of the heat-resistant resin layer is preferably 0.2 to 3μ. The total thickness of the OPP film 2 and the heat-resistant resin layer 3 needs to be 3 to 16 microns, preferably 4 to 11 microns. Here, the total thickness refers to the cross section shown in Figures 1 and 2 when viewed under a microscope.
As shown in the figure, when unevenness is visible on the exposed surface 3a of the heat-resistant resin layer, the thicknesses t ₃ and t ₄ from the smooth surface 2a to the apex of the convex portion of the exposed surface 3a, although not shown in the figure, are When the exposed surface of the heat-resistant resin layer is smooth and has no irregularities, measure the thickness from the smooth surface 2a to this smooth surface at 5 points, find the average value, and use this as the thickness. This is what I did. If the total thickness is thicker than 16 μm, heat transfer takes too long and is not suitable for high-speed recording. Furthermore, it is also unfavorable to make the cartridge more compact and to make the ribbon longer. Total thickness is 3μ
If it is thinner, the strength will be lower and the processability will be poor, which is not good. In addition, the surface roughness Ra of the outer surface of the heat-resistant resin layer needs to be within the range of 0.07 to 1.5 μ, and preferably 0.1 to 1.0 μ.
A more preferable range is 0.2 to 0.8μ. In this way, if the surface roughness of the exposed surface is 0.07 to 1.5μ,
The coefficient of friction between the non-ink laminated surface of the ribbon and the ink laminated surface or the running guide in the cartridge is reduced, and the running performance of the ribbon is improved. Therefore, good runnability is ensured even in the case of a typewriter ribbon based on a thin film of biaxially oriented polypropylene. If the surface roughness Ra is less than 0.07 μ, the coefficient of friction will increase, and the running properties of the film in the cartridge will deteriorate, causing distortion or breakage of typed characters, and stretching or breakage of the film. It becomes easier to On the other hand, if it exceeds 1.5μ, heat transfer from the thermal head will deteriorate, which is unfavorable in terms of printability, etc. In this invention, the type of transfer ink forming the ink layer is not particularly limited as long as it melts when heated, and any known type can be used. Specifically, the main components are a binder component, a coloring component, etc., and, if necessary, a softener, a flexibilizer, a melting point regulator, a smoothing agent, a dispersant, etc. are used as additive components. In short, it is constructed by appropriately selecting and combining well-known materials.
To give specific examples of main components, binder components include paraffin wax, carnauba wax,
Well-known waxes such as ester waxes and various low-melting point polymers are useful, and as the colorant component, carbon black and various organic and inorganic pigments or dyes are useful. Further, the ink includes a sublimation type ink. As a method for providing the ink layer on one surface of the OPP film, well-known methods such as hot-melt coating and solution coating methods such as gravure, reverse, and slit die methods can be used in a state in which a solvent is added. Note that in both the ribbons 1 and 1' of the embodiment shown in FIGS. 1 and 2, an ink layer is provided directly on the surface of the OPP film.
In order to improve the coating properties of the ink, the ink layer and
A coating layer or other polymer layer may be provided between the OPP films. Next, a method for manufacturing a film in which a heat-resistant resin layer is laminated on an OPP film, which is used in the ribbon according to this invention, will be explained. The methods for manufacturing laminated films can be roughly divided into two methods, regardless of the surface roughness Ra of the OPP film:
A heat-resistant resin layer having a rough surface with a surface roughness Ra of 0.07 to 1.5μ is laminated on the OPP film (first
(See figure) How to make surface roughness Ra 0.07~
A method in which a heat-resistant resin is laminated thinly on the rough surface of an OPP film that has been roughened to a thickness of 1.5μ, and the unevenness on the OPP film is exposed on the outer surface of the heat-resistant resin layer (see Figure 2). There is. More specifically, in the former method, polypropylene and a heat-resistant resin are co-extruded and then biaxially stretched vertically and horizontally, and the outer surface of the heat-resistant resin layer is roughened to a predetermined roughness depending on the stretching temperature conditions. A method of adding inorganic particles to a heat-resistant resin, coextruding it, and then biaxially stretching the heat-resistant resin so that the outer surface of the heat-resistant resin layer has a predetermined roughness with the inorganic particles. There is. As a lamination method, in addition to the above-mentioned coextrusion followed by biaxial stretching, a heat-resistant resin is laminated after uniaxial stretching of polypropylene, and then,
A method of stretching (biaxial stretching) in a direction perpendicular to the direction that has already been carried out, or laminating a heat-resistant resin film having the predetermined surface roughness Ra on top of an already biaxially stretched OPP film. There are ways to do this. Alternatively, a biaxially stretched OPP film may be coated with a heat-resistant resin containing inorganic particles. In the latter method, biaxial stretching is performed and the surface roughness on one side is
The most common method is to coat an OPP film with a thickness of 0.07 to 1.5μ with a heat-resistant resin. In order to make the OPP film surface have a predetermined surface roughness Ra, for example, the surface can be mechanically processed,
A method of crystallizing the polymer after melt extrusion, a method of adding inorganic particles to the polymer, or a combination thereof may be used. Next, Examples and Comparative Examples will be described. (Example) Polypropylene of 230°C MI (melt index) = 1.5 g/10 minutes was put into one extruder, poly4-methylpentene-1 (melting point 240°C, MI of 260°C =
A blend of 90% by weight (25g/10min) and 10% by weight of the polypropylene was fed to another extruder, respectively. Then, both were melted and coextruded at 300℃,
It was wound around a cooling drum at 30° C. to obtain an unstretched sheet with a thickness of about 270 μm (thickness of the base polypropylene of about 200 μm). This sheet was stretched 4 times in the longitudinal direction while heating it to 120°C, and then introduced into a tenter at 160°C and stretched 9 times in the transverse direction to give a relaxation rate of 7% and a thickness of 8μ (substrate A laminated film of polypropylene with a thickness of 6 μm was obtained. The base of this laminated film
After applying typewriter ribbon ink at a rate of 10 g/cm ² onto the surface of the OPP film, it was slit into a width of 13 cm ² and wound onto a spool. The cartridge typewriter ribbon thus obtained had a cross-sectional structure as shown in FIG. That is, OPP of the substrate
A heat-resistant resin layer 3 made of a blend of poly-4-methylpentene-1 and polypropylene is laminated on the film 2 to form a laminated film. The surface roughness Ra was 0.061μ, and the surface roughness Ra of the heat-resistant resin layer side surface (non-ink laminated surface) 3a was 0.62μ. An ink layer 5 was provided on the outer surface 2a of the OPP film 2. (Comparative Example 1) A typewriter ribbon was made in the same manner as in Example 1, except that the blend of poly4-methylpentene-1 and polypropylene was not laminated on the OPP film. (Comparative Example 2) A typewriter ribbon was made in the same manner as in Example 1, except that silicon dioxide was added to polypropylene at a ratio of 7% by weight. Table 1 shows the surface roughness Ra of the ink laminated surface and the non-ink laminated surface of the laminated film in the typewriter ribbons of Examples, Comparative Example 1, and Comparative Example 2. Each typewriter ribbon was placed in a cartridge, and this card cartridge was used to perform printing with a typewriter, and the clarity of characters printed on type paper and cartridge running properties were examined.
The results are also shown in Table 1. However, the clarity of the characters and the runnability of the cartridge were examined as follows. Sharpness of Typed Characters Typed characters are magnified 20 times, with no cut-offs,
Observe the fuzz, distortion of letters, thickness, etc. Cartridge running performance Measure the ribbon winding torque in the cartridge. The smaller the number, the better the running performance.

[Effect of idea]

The typewriter ribbon of this invention described above has the following effects and is highly practical. Effect Characters with a large number of strokes are recorded clearly. This means that the surface roughness Ra of the biaxially stretched polypropylene film surface on the side where the ink layer is provided is 0.2μ.
This is because the following. Effect Good running performance even if it is thin. This is the surface roughness of the exposed surface of the heat-resistant resin layer.
This is because Ra is 0.07 to 1.5μ and the coefficient of friction is reduced. Effect: High-speed recording is possible. The total thickness of the biaxially oriented polypropylene film and the heat-resistant resin layer is 3 to 16μ, and the surface roughness of the exposed surface of the heat-resistant resin layer is Ra.
is 1.5μ or less, heat transfer from the thermal head to the ink layer is good, and the film can be transported at high speed. Effect: There is no need to worry about thermal head sticking. This is because a heat-resistant resin layer is always interposed between the biaxially stretched polypropylene film and the thermal head.

[Brief explanation of drawings]

1 and 2 are structural explanatory diagrams of an embodiment of the typewriter ribbon according to this invention, respectively. 1, 1'... Typewriter ribbon, 2... Biaxially stretched polypropylene film, 3... Heat resistant resin layer, 4... Ink layer.

Claims (1)

[Claims for Utility Model Registration] (1) A type used in typewriters with thermal head-type heating printing means, which has a thermal transfer layer consisting of an ink layer that melts when heated by a thermal head on one side of a strip-shaped film serving as a base. In the lighter ribbon, the base is a biaxially oriented polypropylene film, the heat resistant resin layer is provided on one side and the ink layer is provided on the other side, and the total thickness of the biaxially oriented polypropylene film and the heat resistant resin layer is 3 to 3. The surface roughness of the ink layer side surface of the polypropylene film is 16μ.
A typewriter ribbon having an Ra of 0.2μ or less and a surface roughness Ra of the exposed surface of the heat-resistant resin layer of 0.07 to 1.5μ. (2) The thickness of the biaxially stretched polypropylene film is 2
The typewriter ribbon according to claim 1 of the utility model registration claim, which has a thickness of ~15μ.