JPH03247449A - Ink coating method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an ink coating method, and more particularly to an ink coating method for printing vertical striped patterns of two or more colors on the surface of a printing material.

(Prior art and its problems) Conventionally, when printing output prints from computers or word processors using a thermal transfer method, a thermal transfer sheet with a heat-melting ink layer provided on one side of a base film has been used. .

This conventional thermal transfer sheet has a thickness of 1 mm as a base film.
Using paper such as capacitor paper or paraffin paper with a thickness of 0 to 20 μm, or a plastic film such as polyester or cellophane with a thickness of 3 to 2041 m, a layer of heat-melting ink made by mixing coloring agents such as pigments and dyes with wax is applied. It is manufactured by coating it to provide a uniform thickness.

The conventional thermal transfer method described above has been used to print a variety of characters, but recently it has been used for printing barcodes on barcode labels because of its simplicity and suitability for small lot printing. It started to be used.

Labels with barcodes printed on them are attached to many products, but when these products are packaged, there is an inconvenience in that the contents of the product cannot be easily identified with the naked eye from the barcode. In some cases, it was required to clearly indicate the contents of the item using a felt-tip pen, etc. This type of method degrades the appearance of the packaging and is very complicated.As a way to solve these problems, we use thermal transfer sheets for printing barcodes as shown in Figures 1 to 3. However, the present inventor proposed a method of printing a black barcode in the area 2a and printing a chromatic mark on the article using chromatic ink in the area 2b, thereby identifying the contents of the article by color.

Thermal transfer sheets as shown in FIGS. 1 to 3 are obtained by forming ink layers 2a and 2b in a vertical striped pattern on one surface of a base film l using inks of two or more colors by a method as shown in FIG. However, if the chromatic area 2b is first coated with chromatic ink and then the black ink 2a is coated, if the performance of the doctor 5 is poor or the doctor 5 is worn out, the gravure plate 3 may The black ink in the non-image area 8 is not sufficiently scraped off, and the black ink 2a is also applied to the chromatic area 2b.
There is a problem that stains (b) occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the prior art described above and to provide an ink coating method that does not cause the above-mentioned stains.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a method in which the printing material is passed between a gravure plate and its plate cylinder, and hot-melt ink of two or more colors is coated in a vertical striped pattern in the longitudinal direction of the printing material. This ink coating method is characterized in that the surface of the plate cylinder corresponding to the non-image area of the plate is made into a concave portion.

(Function) By making the surface of the plate cylinder corresponding to the non-image area of the gravure plate into a recessed part, even if ink remains in the non-image area of the gravure plate, the gravure plate and the plate cylinder are in close contact. do not. Therefore, the ink remaining in the non-image area of the gravure plate is not transferred to the printing material, and the printing material is not stained.

(Preferred Embodiments) Next, the present invention will be explained in more detail with reference to preferred embodiments.

FIG. 1 is a diagram illustrating the appearance of a thermal transfer sheet obtained by the method of the present invention, and FIG. 2 is a diagram showing its cross section.

The thermal transfer sheet obtained by the method of the present invention is shown in Figures 1 and 2.
As schematically shown in the figure, when forming a heat-fusible ink layer on one side of the base film 1, most of this ink layer is a black ink layer 2a, and the rest is a chromatic ink layer 2b. It is characterized by

An article in which a barcode is printed in black on a barcode label using such a thermal transfer sheet, and the barcode label is attached to the top, bottom, or either side of the printed barcode with colored ink. Print a specific mark that corresponds to the content. By attaching such a barcode label to the packaging of an article, the contents of the article can be easily identified with the naked eye.

Further, the chromatic ink portion is not limited to one color, but may be two colors as shown in the third figure, or may be three or more colors.

The thermal transfer sheet may be in the form of a continuous sheet as shown in the first figure, or may be in the form of a sheet formed by cutting this into an appropriate size. Further, the width of these thermal transfer sheets varies depending on the printer used, and may be any width. Further, the black ink layer 2a accounts for 50 to 90% of the film, and the chromatic ink layer 2b accounts for about 1 to 50%.

As the base film 1, the same base film used in conventional thermal transfer sheets can be used as is, and other materials can also be used, and there is no particular restriction.

Specific examples of preferred base films include polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride,
There are plastics such as polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, and ionomers, papers such as condenser paper and paraffin paper, and nonwoven fabrics, as well as base films that are composites of these materials. You can.

The thickness of this base film can be changed as appropriate depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 25 μm.

The hot-melt ink used in the present invention comprises a colorant and a vehicle, and may further contain various additives as required.

As this coloring agent, carbon black is of course suitable for the black ink layer part, and for other chromatic ink parts,
For example, pigments such as cyan, magenta, and yellow are used.

The vehicle used includes wax as a main component, and mixtures of wax with drying oil, resin, mineral oil, cellulose, rubber derivatives, and the like.

Representative examples of wax include microcrystalline wax, carnauba wax, paraffin wax, and the like. Furthermore, various waxes are used, such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolatum, as-needed wax, fatty acid ester, fatty acid amide, etc. It will be done.

Further, in order to provide the hot-melt ink layer with good thermal conductivity and melt transferability, a thermally conductive substance can be blended into the hot-melt ink. Examples of this substance include carbonaceous substances such as carbon black, aluminum, copper, tin oxide, and molybdenum dioxide.

As a method for forming the heat-fusible ink layer on the base film, a gravure printing method is suitable, and other known methods may be used.

A particularly preferred method in the present invention is as shown in FIG.
When forming the black ink layer 2a on the base film 1 on which the chromatic ink layer 2b has already been formed in the previous step, the black gravure plate 3 is immersed in the molten black ink tank 4, and the ink 2
A is placed on the gravure plate 3, and the black ink 2a is transferred to a desired area of the base film l.

At this time, the black ink 2a in the area corresponding to the chromatic ink layer 2b (which is a non-image area for black ink) is scraped off from the gravure plate 3 by the doctor 5.
The black ink 2a is never transferred onto the chromatic ink layer 2b.

However, if the doctor 5 has poor performance or is worn out, the black ink 2a is also transferred onto the chromatic ink layer 2b, resulting in staining of the chromatic ink layer 2b.

In the present invention, we have discovered a method to effectively solve these problems. That is, in the impression cylinder 6 that presses the base film l against the gravure plate 3, the area corresponding to the chromatic ink layer 2b (the non-image area with respect to the black ink 2a) is made into the recessed part 7 (by which In the area 7, the chromatic ink layer 2b is not pressed against the gravure roll 3, so even if the performance of the doctor 5 deteriorates and black ink remains in the non-image area 7 of the gravure plate 3, the black ink is not pressed against the gravure roll 3. 2a is the base film 1
Since the black ink 2a is not transferred onto the chromatic ink layer 2b, the chromatic ink layer 2b is not stained by the black ink 2a.

Subsequently, the obtained film is cut into 2 to 3 equal parts as required to obtain a thermal transfer sheet as shown in the first figure.

In the above method, the black ink layer 2a is formed after the chromatic ink layer 2b is formed, but it goes without saying that the order may be reversed.

The thickness of the ink layers 2a, 2b to be formed should be determined so as to balance the required concentration and thermal sensitivity, and should be 0.00000.
It is in the range of 1 to 30 μm, preferably in the range of 1 to 20 μm.

In the present invention, a surface layer (not shown) made of wax may be formed on the ink layer. The surface layer forms a part of the transfer film, forms the surface in contact with the transfer paper, seals the printed area of the transfer paper during transfer, prevents scumming, and prevents the ink layer from being covered. It has the function of improving adhesion to transfer paper.

When a heat-sensitive material is used for the base film 1, it is preferable to provide a heat-resistant slipping layer (not shown) on the surface in contact with the thermal head to prevent sticking of the thermal head. The basic components of the heat-resistant slipping layer are a heat-resistant resin and a substance that functions as a heat release agent or a lubricant.

By providing such a heat-resistant slipping layer, thermal printing is possible without sticking even on thermal transfer sheets based on heat-sensitive plastic films, and it is possible to print on thermal printing sheets without sticking. Benefits such as ease of use can be taken advantage of.

Thermal transfer images generally have glossy and beautiful prints, but they can also make documents difficult to read, so matte prints are sometimes desirable.In such cases, for example, the applicant's proposal ( (Japanese Patent Application No. 58-208306), a matte layer is provided by coating a base film with an inorganic pigment such as silica, calcium carbonate, etc. dispersed in an appropriate solvent, and then a heat-meltable It is preferable to form a thermal transfer sheet by forming an ink layer.Alternatively, the base film itself may be matted and used (the technique of Japanese Patent Application No. 58-208307, also proposed by the applicant).

Although the method of the present invention has been described above using the production of thermal transfer sheets as a representative example, the method of the present invention is not equally limited to the production of thermal transfer sheets, the printing material to be printed is not limited to film, and the ink is hot melt ink. However, the same effect can be achieved with any printing material and any ink. Of course, the printing material may be a continuous long material or a sheet-fed material.

(Example) Next, the present invention will be described in more detail with reference to Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 A polyethylene terephthalate film with a thickness of 3.5 μm was used as a base film, and red ink with the following composition was applied to one side of the base film using a gravure printing method at a coating amount of 3.5 g/rrr for 3 inks with a width of 2 cm. After coating, using a gravure roll as shown in Figure 4, three coats of black ink having the following composition were applied at a rate of 3.5 g/rrf using a gravure printing method and cooled, and then cut into three sections. This was then wound up into a roll to obtain a thermal transfer sheet as shown in the first figure. No stains due to black ink were observed in the red portion of this thermal transfer sheet.

Kumi Eno 1 Red pigment 15 parts ethylene/
Vinyl acetate copolymer (EVA Flex 31O1 manufactured by Mitsui Polychemicals) 8 parts paraffin wax (paraffin 150F, manufactured by Hiki Seiro)
50 parts carnauba wax 25 parts 凰亘ヱ2ヱ1 Carbon black (Diablack G, manufactured by Mitsubishi Kasei)
15 parts ethylene/vinyl acetate copolymer (EVA Flex 310, manufactured by Mitsui Polychemicals) 8 parts paraffin wax (paraffin 1
50F, made by Hiki Seiro) 50
25 parts carnauba wax Next, using the above thermal transfer sheet, a barcode label was used as the transfer paper, and a barcode and a red mark were printed using a commercially available barcode printer.

Example 2 A barcode with a green mark was printed on a barcode label in the same manner as in Example 1 except that green ink was used as the chromatic ink in Example 1.

The barcode labels of the above two examples were attached to packages that had the same appearance but different contents.

The different contents of these packages can be easily identified with the naked eye even from a distance.

(Effect) According to the present invention as described above, by making the surface of the plate cylinder corresponding to the non-image area of the gravure plate into a recessed part, even if ink remains in the non-image area of the gravure plate, the gravure There is no close contact between the plate and the plate cylinder. Therefore, the ink remaining in the non-image area of the gravure plate is not transferred to the printing material, and the printing material is not stained.

[Brief explanation of drawings]

FIGS. 1 to 3 are diagrams illustrating a part of the thermal transfer sheet obtained by the method of the present invention, and FIG. 4 is a diagram illustrating the method of the present invention for producing those thermal transfer sheets. It is. 1: Base film 3: Gravure roll 5: Doctor 7: Concave portion 2: Ink layer 4: Ink tank 6: Impression cylinder 8/non-image area

Claims (1)

[Claims] (1) In a method in which the printing material is passed between a gravure plate and its plate cylinder, and two or more colors of ink are applied in a vertical striped pattern in the longitudinal direction of the printing material, the non-image area of the gravure plate is An ink coating method characterized by forming a concave portion on the surface of the corresponding plate cylinder.