JPS5812792A - Composite material for planography - Google Patents

Abstract

PURPOSE:To provide the titled composite material free from fatigue rupture of a metallic foil, excellent in useful life length, printing durability and inexpensive, by combining a metallic foil with a support which has a strength-elongation characteristic equal to that of the metallic foil. CONSTITUTION:The metallic foil e.g., an aluminum foil is combined with the support (e.g., cardboard) which has a strength-elongation characteristic comparative to that of the foil by an extrusion laminating system or the like.

Description

Detailed Description of the Invention The present invention relates to a composite material for lithographic printing, and is a composite material consisting of a metal foil and a support (for example, cardboard, plastic, etc.), which has excellent fatigue rupture in the metal foil and excellent printing durability. It is an object of the present invention to provide the above-mentioned composite material for lithographic printing at a low cost.

This lithographic plate takes advantage of the property that water and oil repel each other, and has a hydrophilic non-image area and an oil-sensitive image area with no difference in height on the same plate surface, and is used for printing. In addition to printing plates, which repel fatty ink to the hydrophilic wet parts of the non-printing area and selectively apply ink only to the oil-sensitive printing areas, metal plates are generally used. used. This metal plate includes zinc, aluminum, iron, and special alloy metals.
■Light and easy to handle and will not be damaged.

■Large plates are easy to obtain and inexpensive. ■It is known that it has advantages such as being curved and easy to install for rotary printing presses, but recently, in order to further promote these advantages, there has been a rise in prices especially in recent years. In order to reduce printing costs when using metal aluminum as a plate material, metal foil and cardboard are used instead of the metal aluminum plate material.

Many ideas have been proposed to put into practical use so-called composite printing materials made by laminating woven fabrics, non-woven fabrics, plastic sheets, etc.

However, this type of composite plate material generally has a low printing durability because the metal foil is prone to fatigue rupture, and its printing capacity is usually several hundred copies, and even in the case of high-quality composite plate material, the limit is several thousand copies. has been done. For this reason, even if such a composite plate material can be obtained at a low cost, it does not necessarily function effectively as a substitute for a metal plate, and its use is currently almost discouraged. The reason for this is mainly due to the fact that the printing force f/C of this composite plate material depends decisively on the thickness of the applied metal foil, and of course the thickness of the foil itself becomes a problem. After all, there is a limit to the thickness of the foil, so there is inevitably a limit to the printing power per surface, so we cannot give up.
．． Tei/(It was due to Toto.

Based on the above points, the inventors have determined -1-
As a result of numerous experiments in order to solve the problem of profit path described in the book, I came to discover the following fact.

That is, a huge silk composite material 1 was prepared from the above-mentioned type of support to be laminated on the metal foil 1, and this was used as a specimen to determine the strength and elongation characteristics and printing durability of both materials (metal foil and support material). When we experimentally investigated the relationship between force and force, we discovered that there is an inseparable relationship between them as follows.

The relationship between the dimensions will be explained with reference to the drawings, taking as an example the case of a laminate of aluminum foil and cardboard (support).

First, in order to discuss the essential differences between materials, we will ignore the stress distribution of the metal foil, J: and support composite material O, which correspond to the thickness. Is there stress?
Assuming that, for a single aluminum plate, the stress in the direction of 1 is ±εmm (the tensile stress is (in the -1 direction,
Compressive stress means that stress occurs in the ←) direction)
Therefore, if aluminum foil and cardboard are simply composite 17, the support and the cardboard will be more easily strained by this stress than aluminum foil, ε”Inm (!:
.

Normally, the amount of strain is greater than that of aluminum foil by 0ε/oε=Δε. For this reason, although cardboard is called a support, it cannot be said to be a mechanical support for the aluminum foil against the stress during printing, and as a result, the load on the aluminum foil alone becomes excessive, causing distortion of the aluminum foil. The stress is unilaterally borne at the point where the gauge becomes the same as the stiffness of cardboard, that is, the bend becomes ε'. In order for the aluminum foil to be distorted by 2ε' mm in FIG. 1, an excessive stress of σ+Δr−σ′ must be applied. This excessive stress is repeated every time the plate rotates 111 times in a rotary printing press, so
In each case, the distortion of 1t ε'mm corresponding to z1 is also repeated. Therefore, it naturally accumulates] 1. No. 1 is that the fatigue caused by the process becomes excessive, leading to early fatigue failure. This reduces printing durability. It is clear from the figure that the Δhio rise Δε, which is the cause of this, is influenced by the ε′ of the cardboard that is the support. IL will appear soon.

In order to elucidate the essential problem, we have ignored the influence of the thickness of the painting material. However, in reality, this problem is caused by the thickness of each layer of composite plate materials. are of course different. However, many experiments that take into account the thickness factor have fundamentally shown that it is essential to reduce the above-mentioned fatigue due to the aluminum foil in order to improve printing durability.

Hereinafter, the structure of the composite plate A will be specifically explained based on the present invention.

5- In general, planographic plates undergo permanent deformation due to stress during printing.The prerequisite is not to cause such deformation. This relationship can be discussed only in the straight line section on the diagram within the elastic limit.

Therefore, the slope of the straight line, that is, Zθ4° and lθP in the figure
.

Its characteristics can be expressed by simplifying it to the angle .

If θ, -08 cardboard is an ideal support in terms of t, -, -1 material (without considering the thickness of the material), then aluminum foil and cardboard are mechanically the same material. Therefore, the stress that the aluminum foil receives in the composite plate material is exactly the same as the stress that the aluminum plate material of the same thickness receives. Therefore, if an ideal cardboard like jin is selected, the distortion and fatigue experienced by the aluminum foil and the aluminum plate will be exactly the same, and there will be no difference in printing durability between the two.However, there is a real problem. Therefore, it is very difficult to select a support with a strain amount of 6- (-1-) and (08-0 in both directions of (→). However, the principle of the present invention, the strength of If each f fee is evaluated using the scale of elongation characteristics, its improvement characteristics will become clear.
An ideal support can be easily approached. Is it a material that is advantageous in the (+) direction (tension) of the amount of strain, or is there an improved method that is advantageous in improving the amount of strain in the (+) direction (compression)? It can be evaluated based on θ. Therefore, h- in θP/θA-1 is ideal, but in practice, it has been experimentally proven that if θ, /θ8 is 0.8 or more, it will not have a large effect on printing durability. There is.

Below, we have explained two material approaches for the support, but in reality, changing the thickness of the support is also an important means of approaching θ, /θ, -1. should be considered in conjunction with . This is also important due to practical constraints such as the manufacturing process and economic efficiency of the hariai plate.

Based on this principle, the strength and elongation characteristic of 1/1- is used as a criterion for selecting a support, and the support is limited to cardboard.

Non-woven fabrics, plastic sheets, composite materials of these materials, etc. can be easily selected as supports as long as they satisfy the following conditions, and inexpensive composite plates with quick printing durability can be selected. What you get is what you get.

The present invention will be explained in more detail with reference to Examples below.

Example I Milk carton base paper 2507An' manufactured by A Paper Company 2
After obtaining a plate material by combining 0μ aluminum foil with polyethylene extrusion lamination method, this plate was used as an I) S plate and tested for printing durability on a rotary printing machine, and the aluminum foil broke after about 700 sheets. occurred. In addition to the above, the θ and /θ of this milk carton base paper. When the value was measured, it was found to be 0.73.

Next, the abrasive base paper made by Paper Company B was 110 Vm
2.150 f//m2: and 25oy7. z is selected, its warp is combined with aluminum foil with a thickness of 20μ in the same manner as above to obtain a plate material, and θ, /
The sharpness value and printing durability using a rotary printing press were measured. As shown in Table 1, the results are θ, /θ for rice jq'2509/m'
6 value of 0.96 is the best one-side printing force (indicated by the number of printed sheets), and even after printing 52,000 sheets, there is no negative effect on the lithography and printing quality, and it is suitable for printing more than 5000 sheets. It is certain that R2 Sano'1. It was satisfying.

Table 1 (Note) The printing durability value indicates the breaking limit of plate scraping.

Example 2 Three types of polypropylene films with a medium thickness of 250μ manufactured by Company C were randomly selected, and aluminum foil of 20μ (thickness) was attached to each of them using a two-component type urethane adhesive bond KU-15 (Konishi Co., Ltd.). The plate was laminated using a dry lamination method using a 9-PS plate made by the same company, and the θ, /θ6 values and printing durability were measured in the same manner as in Example 1. The results shown in Table 2 were obtained.As is clear from the wood surface, the stretched film with a θ, /θ6 value of 1.1o had the best printing durability, and even after printing 6,000 sheets, it still remained flat and printed. There were no problems with the quality, and it was much more satisfactory than non-stretched films.

Table 2 (Note) The printing durability values are the same as those in Table 1 (Note). Example 3 Two types of wet-laid nonwoven fabric made of rayon manufactured by Company D (200y)
7. z and] s o y/m'), and a 20μ (thickness) aluminum foil was placed on each of them according to Example 1.
A Ps plate was obtained after compounding in the same manner as above to obtain a plate material.

Next, we measured the θP/θ4 value and printing durability for both, and found that the printing durability of the latter was much faster than that of the former, and even after printing 5,000 sheets, the printing quality was the same as that of the flat plate. The results were extremely good with no defects (see Table 3).

Table 3 (Note) The printing durability values are the same as in Table 1 (total)

[Brief explanation of the drawing]

The drawing shows the strength and elongation characteristics of aluminum foil and cardboard composited therewith. A: Aluminum metal foil, B: Cardboard Patent applicant: Hokuetsu Paper Co., Ltd. 11- o H′ z amount → με

Claims (1)

[Claims] A composite material for lithographic printing characterized by combining a metal foil used as a plate material with a support having strength and elongation characteristics equivalent to that of a car.