JP3167139B2 - Laminated sheet for printing and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated sheet for printing which is excellent in water resistance, printing workability, low chargeability and weather resistance, and a method for producing the same.

[0002]

2. Description of the Related Art Paper or a synthetic resin film is used as a base layer,
As a laminated sheet in which a synthetic resin layer is formed on the surface to take advantage of the characteristics of the resin layer, a photographic paper support, a synthetic paper, and the like are known. As a laminated sheet for printing, for example, inorganic pigments can be mixed into the outermost layer, the function of the resin can be used as it is, or the surface properties can be changed to improve opacity, improve ink adhesion, and suppress static electricity generation. Those provided with such a function are also known. However, since the surface of such a laminated sheet is a non-absorbent material, the ink dries poorly at the time of printing, and as the prints overlap, a load is applied and the ink shifts to the back side, and the printed matter is stained. The printing efficiency is very poor because the paper is peeled off, damaging the stamped surface, and the ink and sheet stick to each other, causing blocking. I have. It is also known to spray starch powder during printing as a method for improving these.

[0003]

Since the surface of the laminated sheet described above is made of a synthetic resin, it hardly absorbs ink during printing, has poor drying, and has problems such as generation of static electricity and poor sliding. ing. That is, if handled carefully using a low-speed, special ink or a special printing method, a corresponding printed matter can be obtained, but it is not satisfactory from the viewpoint of poor productivity and practicality. For example, the generation of static electricity, the slippage and the set-off of the ink can be slightly improved by the above-mentioned inorganic pigment compounding and printing device,
Not enough. For example, in the case of offset sheet-fed printing, a commercially available starch powder can be sprayed at the time of discharge immediately after printing as an ingenuity in printing, so that ink set-off can be considerably eliminated. In the case of offset printing, there are many problems such as the fact that starch powder is eluted by the dampening water and serves as an adhesive to stick the sheets together. In addition, there are problems such as double feeding due to static electricity and poor slippage during paper feeding before printing, and there are limits to the conventionally proposed blending of inorganic pigments and ingenuity in printing. Therefore, the present invention is less slippage of ink and generation of static electricity in the printing operation, slippery,
It is an object of the present invention to provide a laminated sheet for printing with less trouble in paper feeding and discharging.

[0004]

According to the present invention, a base material layer and at least one layer of a thermoplastic synthetic resin laminated on the base material layer are provided. According to the pattern, scattered and independent projections are formed on the printing surface in a number of 0.5 to 50 / cm ² at a height of 5 to 40 μm or 1 to 100 / cm ² at a height of 10 to 500 μm.
Is provided on the non-printing surface by the number of sheets.

According to the present invention, when the thermoplastic synthetic resin is extrusion-coated and laminated on the base material layer, before the resin layer is hardened, the base material layer is cooled and pressure-bonded with a cooling roll having a predetermined pattern of depressions on the surface, The method for producing a laminated sheet for printing according to claim 1, wherein a protrusion is formed on a resin surface.

In order to achieve the above object, the present inventors provide in advance a certain range of protrusions on the surface of the outermost resin layer, that is, alleviate the adhesion between the laminated sheets by the protrusions. Has been found to be very effective.

However, it is extremely difficult to provide predetermined projections on the surface of the outermost resin layer, and it is practically not easy to set the size and the number per unit area to predetermined values.

Further, when a projection is provided on the printing surface,
It is important to control the size (height) and the number of protrusions per area within a certain range so as not to hinder the printing effect. On the other hand, when the projection is provided on the non-printing surface, a relatively large (coarse) projection may be used unlike the case of the printing surface. Of course, it can be provided on both the printed surface and the non-printed surface, and can be combined depending on the picture, the use, and the required degree of the printed matter.

As described above, according to the present invention, when the projections are provided on the printing surface, the projections have a height of 5 to 40 μm in view of the size of the halftone dots of the offset printing and the finish of the printing.
The number is in the range of 0.5 to 50 pieces / cm ² . On the other hand, when the projections are provided on the non-printing surface, the number may be somewhat larger than the printing surface and may be many, and may be 1 to 100 / cm ² at a height of 10 to 500 μm. .

According to the present invention, as a method of providing protrusions on the surface of a resin layer, for example, when a thermoplastic synthetic resin is extrusion-coated and laminated on a base material layer, a predetermined pattern is formed on the surface before the resin is cured. The most effective method is to press-fit and cool with a cooling roll having a concave portion to form a projection on the resin surface.

According to the present invention, it is also possible to provide projections on the surface of the resin layer by a printing method. For example, the projections are formed on the surface of the laminated sheet as a height (height) of ink by gravure printing. However, this method is not suitable for providing a projection having a height of about 30 μm or more.

Examples of the method of providing the cooling roll with a recess include a sand blasting method, an etching method in plate making technology, an electronic engraving method, a laser beam method, and the like. It can be appropriately selected depending on the material and the like.

As the thermoplastic synthetic resin for the outermost layer, for example, polyolefin resins such as polyethylene, polypropylene and polymethylpentene resin, and resins capable of extrusion lamination such as polystyrene, polyester resin and nylon resin can be used. However, depending on the combination with the base material, the adhesiveness may be insufficient. In this case, for example, a graft-modified polyethylene or a copolymer of ethylene and acrylic acid or an acrylate ester may be used as appropriate. Can be enhanced. For example, paper, synthetic resin film, nonwoven fabric, or metal foil can be used as the substrate.

A filler such as an inorganic pigment can be added to the laminated sheet according to the present invention, particularly to the outermost layer thereof, depending on the purpose. That is, titanium oxide, calcium carbonate, silica, talc, kaolin, and the like are effective when it is desired to impart whiteness, opacity, pencil writing, and the like, and contribute to the improvement of generation of static electricity and blocking. Also, functionality such as conductivity can be imparted by kneading carbon black or metal powder.

According to the method for producing a laminated material of the present invention, a thermoplastic synthetic resin is extruded on at least one surface of a paper base layer or a film base layer from a T-die film forming machine, and the surface of a cooling roll is molten. To form the laminated material by cooling, but it is preferable to form a slightly larger and deeper dent on the surface of the cooling roll than intended. Thus, the reason why the recess slightly larger than the target projection is provided is that the resin contracts due to cooling, and the reason why the depth is deeper than the target depth is that the resin does not sufficiently enter the bottom of the recess.

[0016]

EXAMPLES Examples of the present invention and comparative examples are shown below. In addition, about the laminated material obtained by the Example and the comparative example, the following physical properties were measured, and the result was shown to Table 1 and Table 2.

[Measurement physical properties] [Measurement method] 1) Thickness: JIS P-8118 2) Basis weight: JIS P-8118 Printing workability 3) Offset start number: Use Roland offset lithographic printing machine (202B) did. The size of the printing paper is 297 x 429mm
(A-3), with a paper feed speed of 6700 sheets / hour and 3
000 sheets were printed using the same plate under the same conditions with a constant ink density. The atmosphere in the printing room was 20 ° C. × 50% RH. twenty four
After a lapse of time, counting was performed from the bottom (bottom) of the printed matter where 3,000 sheets overlapped, and the place where the ink set-off was started was observed to determine the set-off start number. The ink was manufactured by Toyo Ink Co., Ltd.
TK-CCM-KS was used. 4) Charge (KV): Surface potential meter (KDS-61, manufactured by Kasuga Electric Co., Ltd.)
10) was measured under the same conditions. 5) Number of troubles in feeding / discharging: Number of times the printing press was stopped due to double feed or paper jam during printing in the section of the number of set-off start sheets 6) Evaluation of the stamped surface: Observed the printing finish state such as uneven ink run-in . Evaluation: good ×: bad 7) Coefficient of friction: JIS P-8147

Example 1 Low density polyethylene (MFR 7.2 g / 10 min, density 0.917)
g / cm ³ ) was extruded from a T-die at a temperature of 290 ° C., and laminated on the surface of high-quality paper having a basis weight of 81 g / m ² and a width of 500 mm while blowing ozone-containing air onto the surface of the molten film to be bonded to the paper. At this time, a laminated sheet was obtained by pressure bonding with a mat-like cooling roll in order to uniformly or strengthen and fix the adhesion between the molten film and the paper. On the surface of this mat-like cooling roll, dents having a depth of 40 μm are formed in a number of ² / cm ² ,
It was transferred to the resin surface and became a protrusion on the resin surface. When measured by a stylus meter and an electron micrograph, it was reproduced as a protrusion having a height of 30 μm. At this time, the conditions of the ozone treatment were as follows: the lamination speed of the molten film was 100 m / min, and the air gap was 130 m.
m, the ozone concentration was 40 g / m ³ , and the ozone flow rate was 2 m ³ / hour.

Example 2 A laminated sheet was obtained in the same manner as in Example 1 except that a mat-like cooling roll having a surface with a depth of 11 μm and several 5 / cm ² dents was used. Was.

Example 3 Polypropylene (MFR 25 g / 10 min, density 0.91 g / cm
³ ) 65% by weight of a molten state was added, and 35% by weight of calcium carbonate was added thereto and mixed. Separately, a material not containing the above-mentioned polypropylene filler was prepared, and the resin containing no filler was used as the lower layer in contact with the paper, and the resin containing the above-mentioned filler was used as the outermost layer. 290 from the die
While being pressed at a temperature of ° C with a glossy cooling roll, the sheet was laminated on both sides of a waterproof copy paper having a basis weight of 64 g / m ² and a width of 500 mm to obtain a sheet. However, the cooling roll used for laminating the surface had a concave of 27 μm in depth on the surface at a number of 4 / cm ² . In co-extrusion,
The same ozone treatment as in Example 1 was performed on the surface of the molten resin film, which is the lower layer in contact with the paper, to be bonded to the paper. The water-resistant copy paper used in this example was prepared by using a high-quality paper as a base paper and applying a coating solution of starch / polyvinyl alcohol = 80/20 at an application amount of 1
This is a Xerograph copy paper having a Stöckigt size of 30 seconds coated with a size press at ２2 g / m ² .

[0021]

Example 4 In Example 3, the glossy cooling roll used for laminating on the front surface had no dent, and the depth of the dent on the surface of the glossy cooling roll used for laminating the back surface was lower. A laminated sheet was obtained in the same manner as in Example 3, except that the number was 110 μm and the number was 2 / cm ² .

Comparative Example 1 Example 1 was repeated except that the mat-like cooling roll used in the case of lamination had no dent.
In the same manner as in the above, a laminated sheet was obtained.

Comparative Example 2 Example 3 was repeated except that the glossy cooling roll had no dents on both sides when laminating.
In the same manner as in the above, a laminated sheet was obtained.

Example 5 In Example 1, the polypropylene used in Example 3 was used in place of the low-density polyethylene, and the stretched polypropylene film (OPP) was used in place of the high-quality paper. 10 μm / m at 11 μm
^A laminated sheet was obtained in the same manner as in Example 1 except that the ^two sheets were used.

Comparative Example 3 Example 5 was repeated except that the mat-like cooling roll used in the case of laminating had no dents.
In the same manner as in the above, a laminated sheet was obtained.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

According to the present invention, there is provided a laminated sheet for printing in which thermoplastic synthetic resin is laminated for water resistance and weather resistance, and the surface resin layer is provided with independent projections scattered according to a predetermined pattern. Thus, printing workability can be greatly improved. Specifically, by making it slippery and reducing the degree of adhesion between the front and back, it has the effect of generating static electricity on the printing press and smoothing the supply and discharge of paper. It was found that the set-off of the ink had a great effect. In addition to reducing or eliminating problems on the printing press, if a large number of printed materials can be stacked, the frequency of board removal can be reduced, and the space for leaving the printed materials until the ink is dried can be greatly saved. In addition, since the adhesion is relaxed, air can flow in and out and the oxidative polymerization of the ink can be promoted, so that the next printing, processing, and sending to the cutting process can be performed in a short time, which is a great harvest.

Continuing from the front page (72) Michio Takano, Chichikaigan, Chiba Pref., Mitsui Oil Chemical Industry Co., Ltd. (72) Inventor Takeshi Harada, Chikashikaigan, Ichihara City, Chiba Pref. References JP-A-62-248639 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 1/00-7/02 D21H 1/00-27/42

Claims (4)

(57) [Claims] 1. A base material layer and at least one layer of a thermoplastic synthetic resin laminated on the base material layer. At least one surface of the synthetic resin layer has scattered and independent projections in accordance with a predetermined pattern. At a height of 5 to 40 μm
0.5 to 50 pieces / cm ^{2 on} the printing surface or 10 to 500 height
A laminated sheet for printing, which is provided on a non-printing surface in a number of 1 to 100 pieces / cm ^{2 in} μm. 2. The laminated sheet according to claim 1, wherein the base sheet is paper. 3. The laminated sheet according to claim 1, wherein the base layer is a synthetic resin film. 4. When extruding and laminating a thermoplastic synthetic resin on a base material layer, before the resin layer is cured, it is cooled and pressure-bonded by a cooling roll having a concave of a predetermined pattern on the surface, and a protrusion is formed on the resin surface. The method for producing a laminated sheet for printing according to claim 1, wherein: