JPH0241430B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite pressure-sensitive copying sheet, and more specifically, in a composite pressure-sensitive copying sheet of carbonless and back carbon, which is provided with a carbonless color developer layer on the front surface and a carbon ink layer on the back surface. It is an object of the present invention to provide a composite pressure-sensitive copying sheet that improves ink setting properties during printing, prevents reduction in surface whiteness due to penetration of back carbon ink, and has excellent copyability. Generally, carbonless paper contains an upper paper coated with fine capsules containing an electron-donating colorless or light-colored leuco dye dissolved in an organic solvent (capsule oil) on the back side, and an electron-accepting color developer. It consists of a bottom paper with a color developing layer on its surface, and these two
By stacking the seeds so that the coated surfaces face each other and applying pressure with a ballpoint pen or typewriter, the capsule in the pressurized area is destroyed, and the capsule oil containing the leuco dye is transferred to the color developing layer, causing a color reaction. In particular, a printed record can be obtained. On the other hand, back carbon paper has been widely used for office documents since ancient times, and pigments such as black, navy blue, and red are mixed with waxes such as paraffin wax, synthetic wax, castor oil, cylinder oil, and calcium carbonate. Solid ink mixed with filler is heated and melted, and then printed on the back side of high-quality paper or medium-quality paper using a flexo printing machine or a convex (intaglio) printing machine. Normally, when back carbon paper is placed on top of plain paper such as high-quality paper and pressure is applied with a ballpoint pen or typewriter, the carbon ink in that area is transferred to the plain paper and printed. In recent years, the demand for these types of copy paper has increased significantly due to the rationalization of office work, the development of the information industry, and the spread of computer computers, and their uses have also diversified. Composite types of slips that take advantage of this have come into use. Taking delivery slips from department stores as an example, slips such as the one shown in FIG. 1, which are made of a combination of back carbon paper and one-time carbon paper, have traditionally been used. In the figure, sheets 1, 2, 3, and 6 are back carbon paper with carbon ink layer A on the back side, sheets 4 and 7 are high-quality paper, and 5 is one-time carbon paper. , 2 is the sales floor receipt, 3 is the product attachment, 4 is the shipping receipt, 6 is the delivery slip,
7 functions as a delivery note. Of these, slips 4 and 7 are read using an optical reader (OCR).
This is a so-called OCR paper that is read by a computer and stored and processed by a computer, and is printed and recorded by the transfer of ink from the back carbon papers 3 and 6. Due to its characteristics, OCR paper requires a strong contrast between the printed part and the blank paper part, and because it does not like the reading device to get dirty, one-time carbon paper is 5 is inserted. However, the above-mentioned slip has disadvantages such as getting the customer's receipt slip 1 made of back carbon paper, which stains hands and clothes, and the need to insert one-time carbon paper 5, which does not function as a slip. , slips such as the one shown in Figure 2, which are a combination of carbonless paper and back carbon paper, have come into use. In Figure 2, 1
1 is a carbonless upper paper, 12 and 16 are carbonless lower papers with a carbon ink layer A on the back side,
13 is back carbon paper, 14 is OCR paper with leuco dye-containing capsule layer B on the back side, 17 is OCR paper with leuco dye-containing capsule layer B on the back side.
It is OCR paper. Further, C in the figure indicates a carbonless color developing layer. The functions of each slip correspond to the slips in Figure 1, with 11 being a customer receipt and 12 being a customer receipt.
13 is a sales counter, 13 is a product attachment, 14 is a shipping receipt, 16
is a delivery slip, and 17 is a delivery slip. In the slip shown in Figure 2, customer receipt slip 11 and shipping receipt OCR
By using carbonless top paper for the paper 14, it has become possible to remove the carbon paper one-time while eliminating the risk of staining the customer's hands. The present invention provides the above-mentioned slips with 12,1
This is an improved composite pressure-sensitive copying sheet used as No. 6, which has a carbonless color developing layer on the front surface and a carbon ink layer on the back surface. Normally, this composite pressure-sensitive copying sheet is printed using a flexo or relief (intaglio) printing machine using a flexo or relief (intaglio) printing machine to print hot-melt carbon ink on the back side of a rolled carbonless base sheet according to the layout. It is created by However, in the above-mentioned carbon ink printing, since the front and back surfaces of the sheet come into contact when the sheet is rolled up, there is a problem in that the carbon ink transfers to the carbonless color developing layer and causes stains. This is because the color developing layer has good receptivity to capsule oil etc. due to its original function, and the inability to obtain the set-off properties of ordinary back carbon paper is a major hindrance in high-speed printing. It's summery. As a countermeasure to this problem, it has been attempted to add calcium carbonate, which has good oil absorption properties, to the base paper.
In this case, the carbon ink penetrates and is adsorbed onto the paper surface, improving the set-off properties of the ink, but on the other hand, due to the penetration of the ink, the whiteness of the surface decreases, so-called see-through, and the ink bleeds toward the surface. The so-called strike-through phenomenon occurs, or the copying ability deteriorates, resulting in a decrease in the commercial value of the back carbon paper. Particularly when a large number of copies of a slip are to be made, it is necessary to reduce the thickness of the copy paper, so it is difficult to prevent see-through and strike-through. In order to improve the above-mentioned drawbacks, the inventors of the present invention have conducted extensive research and found that by applying an opaque paint consisting of a specific combination of fillers and a binder as an undercoat to the carbon ink layer, the composite pressure-sensitive copying machine has excellent performance. It has been found that a sheet can be obtained.
That is, the present invention is characterized in that an opaque layer consisting of a binder and a filler containing three types of kaolin clay, calcium carbonate with an average particle size of 2 μ or less, and titanium oxide is provided between the support and the carbon ink layer. The present invention provides a composite pressure-sensitive copying sheet. When carbon ink is printed solidly through the opaque layer configured as described above, the set-off property of the carbon ink also improves in the developing layer on the front side, which is forced to come into contact with the carbon ink layer on the back side when wound up. Because of this, it doesn't get dirty. In addition, since no show-through or strike-through phenomenon occurs, the whiteness of the color developing layer is maintained and the contrast of color printing is clear, while it also has excellent copying ability as a back carbon paper. These excellent properties are probably due to the fact that the flat-shaped kaolin clay suppresses excessive penetration of the carbon ink, and at the same time, the ink is properly adsorbed and fixed by the fine particles of calcium carbonate. Sets up quickly,
It is believed that this prevents print-through and improves copyability, and the combination of titanium oxide, which has excellent opacity, eliminates see-through and maintains a high degree of whiteness on the developing surface. . As mentioned above, the present invention uses three types of fillers with different properties in combination to obtain an unprecedented composite pressure-sensitive copying sheet, but in order to achieve the purpose of the present invention in a well-balanced manner The blending ratio of the three types of fillers is 20 to 70 parts of kaolin clay, 15 to 70 parts of calcium carbonate with an average particle size of 2μ or less, and 5 to 30 parts of titanium oxide.
It is preferable to set it as part. Note that other fillers may be added within a range that does not impede the effects of the present invention. Furthermore, as a binder for adhesively fixing the filler, a natural or synthetic polymer used in general coating materials is used. Opaque paints are prepared by adding 15 to 35 parts of these binders to 100 parts of total filler. The type and blending ratio of the binder are appropriately selected depending on the required surface strength of the coating layer, but when the synthetic polymer emulsion is used alone or in combination with other binders, good printability and water resistance can be achieved. can get. The paint prepared as described above was coated on the back side of the support having a carbonless color developing layer on the surface using a coating machine such as an air knife coater, blade coater, or roll coater in an amount of 5 to 10 g/m ² . The coating is preferably applied at a concentration of 6 to 7 g/m ² to form an opaque layer. Further, using a flexo printing machine, hot melted carbon ink is printed all over the opaque layer of the roll to obtain a composite pressure-sensitive copying sheet. The present invention will be described below with reference to Examples. Example 1 Dissolve 0.21 parts by weight of sodium hexametaphosphate as a dispersant in 130 parts by weight of water, and add kaolin to this solution.
75 parts by weight was added to prepare a kaolin dispersion.
Next, 0.05 parts by weight of sodium polycarboxylate as a dispersant was dissolved in 11 parts by weight of water, and then 5 parts by weight of titanium oxide was added to prepare a titanium oxide dispersion. A calcium carbonate dispersion was prepared by dissolving 0.25 parts by weight of sodium polycarboxylate in 32 parts by weight of water, and then adding 20 parts by weight of calcium carbonate. While stirring 205 parts by weight of the kaolin dispersion prepared as above, 16 parts by weight of a titanium oxide dispersion and 52 parts by weight of a calcium carbonate dispersion were added, and then styrene-butadiene copolymer latex (solid content 46 parts by weight) was added.
%) and 50 parts by weight of oxidized starch (solid content 20%) were added to create a paint that forms an opaque layer. The paint thus obtained was applied to the back side of commercially available carbonless paper (NW40B, manufactured by Jujo Paper Industries) at a coating amount of 6 to 7 g/m ² to form an opaque layer. Furthermore, carbon ink (TMW-13S indigo, manufactured by Teikoku Ink) was printed on this opaque layer at a coating amount of 5 to 6 g/m ² to produce a composite pressure-sensitive copying sheet. Examples 2 to 14 Composite pressure-sensitive copying sheets were obtained in the same manner as in Example 1, using kaolin, titanium oxide, and calcium carbonate as shown in Table 1. Comparative Example 1 A carbon ink layer was directly formed on the back side of a commercially available carbonless base paper (NW40B, manufactured by Jujo Paper Industries) without providing an opaque layer. Comparative Examples 2 to 5 As shown in Table 1, composite pressure-sensitive copying sheets lacking at least one of kaolin, titanium oxide, and calcium carbonate were obtained in the same manner as in Example 1. The following quality tests were conducted on the composite pressure-sensitive copying sheets shown in the above Examples and Comparative Examples. (1) Opacity: Measure the reflectance using a Hunter reflectance meter (manufactured by Toyo Seiki,
(using a green filter), and the reflectance ratio was expressed as a percentage. The higher the value, the better. (2) Whiteness after ink application: Measure the reflectance of the sheet surface with a Hunter reflectance meter (using a blue filter)
It was measured by The higher the value, the less see-through it is, which is preferable. (3) Strike-through: The strike-through of carbon ink onto the sheet surface was visually observed and evaluated. (4) Set-off property: The degree of transfer of carbon ink to the developing layer was evaluated by observing with the naked eye. (5) Copying suitability: The sheet was placed on top of high-quality paper, type-printed, and the density of carbon ink transferred to the high-quality paper was observed and evaluated with the naked eye. The test results are shown in Table 1.

[Table] From Table 1, the composite pressure-sensitive copying sheet according to the example achieved satisfactory results in all evaluation items. In particular, it has been found that extremely excellent quality can be obtained when the blending ratio of fillers is 20 to 70 parts of kaolin clay, 15 to 70 parts of calcium carbonate with an average particle size of 2 microns or less, and 5 to 30 parts of titanium oxide.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a slip made by combining back carbon paper and one-time carbon paper, and FIG. 2 is an explanatory diagram showing an example of a slip made by combining carbonless paper and back carbon paper to which the present invention is applied. be. 1, 11...Customer copy, 2,12...Sales counter copy,
3, 13...Product pasting, 4,14...Shipping receipt, 5
... One-time carbon paper, 6, 16 ... Delivery slip, 17 ... Delivery slip, A ... Carbon ink layer,
B... Leuco dye-containing capsule layer, C... Carbonless color developing layer.

Claims (1)

[Scope of Claims] 1. In a composite pressure-sensitive copying sheet comprising a carbonless color developing layer on the surface of a support and a carbon ink layer on the back, kaolin clay is provided between the support and the carbon ink layer. , a composite pressure-sensitive copying sheet comprising an opaque layer comprising a binder and a filler containing calcium carbonate and titanium oxide having an average particle size of 2 μm or less. 2 The blending ratio of filler is 20 to 70 parts of kaolin clay,
The composite pressure-sensitive copying sheet according to claim 1, characterized in that it contains 15 to 70 parts of calcium carbonate and 5 to 30 parts of titanium oxide with an average particle size of 2 μm or less.