JP2007091241A - Method for selecting protective material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for selecting an inexpensive protective material that can prevent the sensitivity deterioration of a coating layer from occurring. <P>SOLUTION: A patch cardboard is selected based on an amount of moisture release from the patch cardboard to put limit on an amount of moisture released from the patch cardboard according to selection, thus preventing the sensitivity deterioration of the coating layer of a PS printing plate. Specifically, since the sensitivity deterioration of the coating layer of the PS printing plate can be prevented without using a dry patch board, a process of drying the patch board can be omitted, which allows cutdown in air-conditioning facility investment costs, electricity bill, etc. The above selection also solves a problem concerning PS printing plate packaging of the sensitivity deterioration of the coating layer of the PS printing plate caused by direct or indirect contact between the patch cardboard and the PS printing plate, can realize the inexpensive patch cardboard, and further solves an environmental problem posed by a conventionally used low-density polyethylene laminated patch cardboard. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for selecting a protective material for protecting a lithographic printing plate.

  Photosensitive lithographic printing plates (hereinafter referred to as “PS plates” where appropriate) are generally subjected to surface treatments such as graining, anodizing, silicate treatment, and other chemical conversion treatments on a support such as a sheet-like or coil-like aluminum plate. Are performed alone or in appropriate combination, and then, after the photosensitive solution is applied and dried, it is cut into a desired size. This PS plate is subjected to plate making processing such as exposure, development processing, and gumming, and is set in a printing machine, and ink is applied to print characters, images, and the like on the paper surface.

  In such a PS plate, protective cardboards (hereinafter referred to as “contact balls”) are arranged above and below the laminated PS plate to prevent the PS plate from being bent, deformed by external force, and damaged. The contact ball and the PS plate are contacted directly or indirectly (when a slip sheet is disposed between the contact ball and the PS plate), whereby the photosensitive layer or the heat-sensitive layer of the PS plate (hereinafter, these are collectively referred to as “ There is a problem in that the sensitivity of the “coated layer” decreases.

  The cause of this decrease in sensitivity is that moisture generated from the hitting ball affects the coating layer. As in Patent Document 1, it is generated from the hitting ball by laminating an unstretched polypropylene film on the surface of the hitting ball. Although there is a method of preventing moisture from being lost and preventing the sensitivity of the coating layer from being lowered, there is a high cost due to the unstretched polypropylene film or a burden on environmental problems.

On the other hand, the lithographic printing plate has changed from a conventional lithographic printing plate to a lithographic printing plate compatible with a thermal laser, and the influence of moisture generated from the contact ball on the coating layer has become extremely large.
JP 2001-233385 A

  In view of the above facts, an object of the present invention is to provide an inexpensive method for selecting a protective material that can prevent a decrease in sensitivity of a coating layer.

  The invention according to claim 1 is a method for selecting a protective material that is disposed at least on the uppermost portion of a laminated lithographic printing plate, protects the lithographic printing plate, and is packaged together with the lithographic printing plate by a packaging material, Based on the correlation between the laser sensitivity for exposing the lithographic printing plate and the amount of moisture released from the protective material, a protective material for the amount of released water that releases water with the laser sensitivity of 100% or less is selected. To do.

  In the first aspect of the invention, based on the correlation between the laser sensitivity for exposing the lithographic printing plate and the amount of moisture released from the protective material, the protective material having the amount of moisture released so that the laser sensitivity is 100% or less is used. Yes. Thus, by selecting the protective material based on the amount of water released, the amount of water generated from the protective material is defined. Thereby, the sensitivity fall of coating layers, such as a photosensitive layer of a lithographic printing plate, or a thermosensitive layer, can be prevented.

  That is, since it is possible to prevent a decrease in sensitivity of the coating layer of the planographic printing plate without using a dried protective material, the step of drying the protective material can be omitted. For this reason, cost reductions such as investment in air conditioning facilities and electricity costs can be achieved.

  Further, by setting the laser sensitivity to 100% or less, the life of the laser can be extended, and the running cost can be reduced.

  In addition, by defining the amount of moisture released from the protective material, it is possible to prevent a decrease in the sensitivity of the lithographic printing plate coating layer, so there is no need to apply a low-density polyethylene laminate on the surface of the protective material, greatly reducing costs. It is possible to solve the environmental problems caused by using a low density polyethylene laminate or the like.

  According to a second aspect of the present invention, in the method for selecting a protective material according to the first aspect of the present invention, the relationship of the amount of released water C = basis ball basis weight M × (A−B) / 100 is satisfied. Here, the amount C of released water is the amount of water released from the protective material, and A is a constant temperature and humidity chamber where the contact ball 62 is left for 240 hours at a temperature of 25 ° C. and a relative humidity of 30 to 70%. Measure the equilibrium moisture content of the protective material after conditioning to reach the equilibrium moisture content by the measurement method according to JIS P 8202, 8203. Correlation between the relative humidity and the equilibrium moisture content of the protection material in a temperature 25 ° C environment The equilibrium water content of the protective material obtained from the approximate expression obtained by the equation B is 48 in a state where the protective material adjusted to the equilibrium water content is packaged together with the planographic printing plate in a temperature of 45 ° C. and a relative humidity of 75%. Approximate formula obtained by correlating the relative humidity and the moisture content of the protective material at a temperature of 25 ° C. after measuring the moisture content of the protective material by measuring according to JIS P 8202 and 8203. Obtained from It is the moisture content of the protective material.

  Since the present invention is configured as described above, the amount of water generated from the protective material is defined by selecting the protective material based on the amount of released water. Thereby, it is possible to prevent a decrease in sensitivity of the coating layer such as a photosensitive layer or a heat-sensitive layer of the lithographic printing plate, and to prevent a decrease in sensitivity of the coating layer of the lithographic printing plate without using a dried protective material. Can do. For this reason, it becomes possible to omit the process of drying a protective material, and it can aim at cost reductions, such as investment in air-conditioning equipment and electricity bill.

  In addition, by regulating the amount of moisture released from the protective material, it is possible to prevent a decrease in sensitivity of the coating layer of the lithographic printing plate, so there is no need to apply a low-density polyethylene laminate or the like on the surface of the protective material, resulting in significant costs. In addition to being able to down, environmental problems due to the use of a low density polyethylene laminate can be solved.

  FIG. 1 shows a processing line 100 of a normal photosensitive lithographic printing plate (hereinafter referred to as “PS plate”).

  On the upstream side (upper right side in FIG. 1) of the processing line 100, a feeder 14 for sequentially unwinding the web 12 previously wound in a roll shape is disposed. The elongate web 12 delivered from the delivery machine 14 is curled and then bonded with a slip sheet 18. Then, they are brought into close contact with each other by charging and reach the notch 20, and the web 12 is provided with a punched portion. Next, the cutting blade 24 constituting the cutting portion 22 moves in the width direction of the web 12 and continuously cuts the web 12 at the punching position.

  In this way, the web 12 cut to a predetermined cutting width is cut by the running cutter 30 at the instructed timing. Thereby, the PS plate 10 having the set size is manufactured. The PS plate 10 is sent to the stacking device 40 by the conveyor 32, and a predetermined number of sheets are stacked by the stacking device 40 to form a stacked body 60.

  On the other hand, a cutting section 39 of cardboard 62 (hereinafter referred to as “abutting ball 62”) as a protective material, which will be described later, is disposed in the vicinity of the stacking device 40, and is cut in advance according to the size of the laminated body 60. Is done.

  The cut application balls 62 are conveyed by the conveyor 70 and placed on at least the uppermost part of the stacked body 60. The contact ball 62 prevents the PS plate 10 constituting the laminated body 60 from being bent, deformed or damaged by an external force.

  And the laminated body 60 is sent to storage warehouses, such as a rack warehouse, or a packaging process through the conveyance part 35, and is packaged with packaging materials (a tape, an interior material, an exterior material, etc.). It is also possible to stack on a skid 41 for an automatic plate making machine.

  Although the PS plate 10 is packaged and shipped as described above, depending on the packaging form, the interleaf paper 18 and other packaging materials may be omitted.

  Here, a photosensitive layer or a heat-sensitive layer (which may be collectively referred to as “coating layer”) is previously formed on a support made of aluminum on the web 12, and this photosensitive layer or heat-sensitive layer is formed. The formed surface is an image forming surface (surface of the web 12) of the PS plate 10. The web 12 is processed by the processing line 100 to have a desired size, and can be used for printing. 10

  The aluminum plate as the support is, for example, JIS 1050 material, JIS 1100 material, JIS 1070 material, Al—Mg alloy, Al—Mn alloy, Al—Mn—Mg alloy, Al—Zr alloy, Al—Mg. -Si-based alloys and the like can be applied. In the manufacturing process of an aluminum plate at a manufacturer, an aluminum ingot that conforms to the above-mentioned standard is manufactured, the aluminum ingot is hot-rolled, and then subjected to a heat treatment called annealing, if necessary, by cold rolling. Finished with a strip-shaped aluminum plate.

  The PS plate 10 is formed by applying a coating layer (a photosensitive layer in the case of a photosensitive printing plate, a thermal layer in the case of a thermal printing plate) on one surface of a thin aluminum plate formed in a rectangular plate shape. Has been. The coating layer is subjected to plate making processing such as exposure, development processing, and gumming, set in a printing machine, and ink is applied to print characters, images, and the like on the paper.

  The specific configuration of the PS plate 10 (web 12) is not particularly limited. For example, a lithographic printing plate that can be directly made from digital data by using a lithographic printing plate for a laser printing plate of a heat mode method and a photon method. It can be a version.

  The surface on which the coating layer is applied is referred to as an image forming surface, and the opposite surface, that is, the surface on which the coating layer is not applied is referred to as a non-image forming surface. Note that the PS plate 10 of the present embodiment is a stage before processing necessary for printing (exposure, development, etc.) and is sometimes referred to as a lithographic printing plate precursor or a lithographic printing plate material. There is also.

The PS plate 10 can be a lithographic printing plate corresponding to various plate making methods by selecting various components in the photosensitive layer or the heat sensitive layer. Examples of specific embodiments of the lithographic printing plate of the present invention include the following embodiments (1) to (11).
(1) An embodiment in which the photosensitive layer contains an infrared absorber, a compound that generates an acid by heat, and a compound that crosslinks by an acid.
(2) An embodiment in which the photosensitive layer contains an infrared absorber and a compound that becomes alkali-soluble by heat.
(3) A mode in which the photosensitive layer includes two layers of a compound that generates radicals upon irradiation with laser light, a layer containing an alkali-soluble binder, and a polyfunctional monomer or prepolymer, and an oxygen blocking layer.
(4) An embodiment in which the photosensitive layer is composed of two layers of a physical development nucleus layer and a silver halide emulsion layer.
(5) A mode in which the photosensitive layer includes three layers of a polymerization layer containing a polyfunctional monomer and a polyfunctional binder, a layer containing silver halide and a reducing agent, and an oxygen blocking layer.
(6) A mode in which the photosensitive layer includes two layers of a layer containing a novolac resin and naphthoquinone diazide and a layer containing silver halide.
(7) A mode in which the photosensitive layer contains an organic photoconductor.
(8) A mode in which the photosensitive layer includes 2 to 3 layers including a laser light absorbing layer to be removed by laser light irradiation, and a lipophilic layer and / or a hydrophilic layer.
(9) A compound in which the photosensitive layer absorbs energy to generate an acid, a polymer compound having a functional group that generates sulfonic acid or carboxylic acid by an acid in the side chain, and an acid generator by absorbing visible light The aspect containing the compound which gives energy to.
(10) The mode in which the photosensitive layer contains a quinonediazide compound and a novolac resin.
(11) A mode in which the photosensitive layer contains a compound that decomposes by light or ultraviolet rays to form a crosslinked structure with itself or other molecules in the layer and an alkali-soluble binder.

  In particular, in recent years, a lithographic printing plate coated with a high-sensitivity photosensitive type coating layer that is exposed with a laser beam or a thermosensitive type lithographic printing plate may be used (for example, the above-described (1) to (3)). Embodiment).

In addition, the wavelength of the laser beam here is not particularly limited. For example,
(A) A laser having a wavelength range of 350 to 450 nm (as a specific example, a laser diode having a wavelength of 405 ± 5 nm).
(B) A laser having a wavelength range of 480 to 540 nm (specific examples are an argon laser having a wavelength of 488 nm, a (FD) YAG laser having a wavelength of 532 nm, a solid laser having a wavelength of 532 nm, and a (green) He—Ne laser having a wavelength of 532 nm).
(C) A laser having a wavelength range of 630 to 680 nm (specific examples are a He—Ne laser having a wavelength of 630 to 670 nm and a red semiconductor laser having a wavelength of 630 to 670 nm).
(D) A laser having a wavelength range of 800 to 830 nm (as a specific example, an infrared (semiconductor) laser having a wavelength of 830 nm).
(E) A laser having a wavelength of 1064 to 1080 nm (specifically, a YAG laser having a wavelength of 1064 nm).

  Etc. Among these, for example, both of the laser beams in the wavelength regions (b) and (c) can be applied to both the lithographic printing plate having the photosensitive layer or the heat-sensitive layer of the above-described aspect (3) or (4). It is. Further, both of the laser beams in the wavelength ranges of (d) and (e) can be applied to both the lithographic printing plates having the photosensitive layer or the heat-sensitive layer of the above-described aspect (1) or (2). Of course, the relationship between the wavelength range of the laser beam and the photosensitive layer or the heat-sensitive layer is not limited thereto.

  The shape or the like of the PS plate 10 is not particularly limited. For example, a photosensitive layer or a single layer of an aluminum plate having a thickness of 0.1 to 0.5 mm, a long side (width) of 200 to 1650 mm, and a short side (length) of 200 to 3150 mm is provided. The heat sensitive layer may be applied.

  The interleaving paper used may be a general one used for a lithographic printing plate, but typical examples are shown below. The specific configuration of the interleaf paper 18 is not limited as long as the coated layer of the web 12 can be reliably protected. For example, paper using 100% wood pulp or synthetic pulp without using 100% wood pulp is used. And paper having a low density polyethylene layer on the surface of these papers can be used.

In particular, paper that does not use synthetic pulp reduces the material cost, so that the interleaf paper 18 can be manufactured at low cost. More specifically, basis weight 20-55 g / m ² made from bleached kraft pulp, density 0.7-0.85 g / cm ³ , moisture 4-6%, Beck smoothness 10-800 seconds, PH 4-6 A slip sheet having an air permeability of 15 to 300 sec can be mentioned, but the present invention is not limited to this.

  Here, the contact ball as the protective material according to the embodiment of the present invention will be described.

  Normally, as shown in FIG. 2, the laminated body 60 is packaged in a state in which the contact balls 62 are arranged above and below the laminated body 60, and prevents the PS plate 10 from being bent, deformed or damaged by an external force. However, since the contact ball 62 and the PS plate 10 are in direct or indirect contact (in the case where the interleaf paper 18 is disposed between the contact ball 62 and the PS plate 10, the configuration shown in FIG. 2), The moisture generated from the balls 62 causes the sensitivity of the coated layer of the PS plate 10 to decrease.

For this reason, the selection method of the contact ball 62 which can prevent the sensitivity fall of the application layer of PS plate 10 is demonstrated below.
1) In a constant temperature and humidity chamber, the contact ball 62 is left for 240 hours at a temperature of 25 ° C. and a relative humidity of 30 to 70% (in 5% increments), and the humidity is adjusted until the equilibrium moisture content is reached. And the moisture content of the contact ball 62 after humidity control is measured by the measuring method by JISP8202 and 8203. By this measurement, the correlation between the relative humidity and the equilibrium moisture content A of the contact ball 62 in a temperature 25 ° C. environment is graphed (see FIG. 3), an approximate expression,
Y = 0.0996X + 2.0001 (Formula 1)
Get.
2) As shown in FIG. 2, the contact ball 62 adjusted to the equilibrium water content A in 1) is directly or indirectly brought into contact with the PS plate 10 compatible with the thermal laser, and the ball 62 and the PS plate 10 are correspondingly applied. Is hermetically packaged with aluminum kraft paper 63.
3) A sample is prepared for each relative humidity set in 1), and left in a packaged state for 48 hours in an environment of a temperature of 45 ° C. and a relative humidity of 75% (so-called thermotreatment).
4) After the thermo-treatment of 3), the moisture content B of the contact ball 62 after opening the sample was measured by the measuring method according to JIS P 8202, 8203. By this measurement, the relative humidity and the contact ball in a temperature 25 ° C. environment were measured. The correlation with the moisture content B of 62 is graphed (see FIG. 4),
Y = 0.064X + 3.6593 (Expression 2)
Get.
5) The correlation between the contact ball equilibrium moisture content A measured in 1) and the contact ball moisture content B measured in 4) is graphed (see FIG. 5), and an approximate expression Y = 0.6385X + 2.4219 (...) Formula 3)
Get.
6) From 5), the amount of water released from the contact ball 62 (hereinafter referred to as “amount of released water”) is calculated for each sample.

Discharged water content C = basis ball basis weight M × (A−B) / 100 (Formula 4)
7) The PS plate 10 that has been in direct or indirect contact with the contact ball 62 is taken out, and the following sensitivity evaluation is performed.

First, the PS plate 10 is exposed by changing the laser output value of the thermal laser using a plate setter (exposure device), and then the PS plate 10 is developed by an automatic developing machine. Then, a laser output value (hereinafter sometimes referred to as “sensitivity”) at which an image is normally formed is measured.
8) Graph the correlation between the released water amount C obtained in 6) and the sensitivity obtained in 7) to obtain FIG.
9) From 8), the amount of released water C ₁ with a sensitivity of 100% or less is obtained, and the contact ball 62 with less sensitivity influence is provided.

Discharged water content C ₁ = basis ball basis weight M × (A−B) / 100 (Formula 5)
10) From the approximate expression (Equation 3) obtained from FIG. 5, the water content B of the hit ball is expressed by the formula of the equivalent water content A of the hit ball, and is substituted into (Equation 5) to calculate the weight of the hit ball and the balance of the hit ball. The relationship of moisture content A is obtained. In other words, when the amount of water released C ₁ is the basis weight M of the hitting ball, if the hitting ball equilibrium water content A or less is selected, it is possible to prevent a decrease in sensitivity of the PS plate 10.

In addition, by obtaining the relative humidity D at which the contact ball equilibrium moisture content A is obtained by the approximate expression (Equation 1) in FIG. It becomes possible to manage the ball moisture content.
12) Here, the basis weight of protective cardboard 62 and _{100g / m 2 ~800g / m 2} . Desirably, a _{200g / m 2 ~400g / m 2} , by fewer basis weight, it is possible to rely lowering the water content of the ball 62 itself, cost reduction can be realized.

Here, when the basis weight of the contact ball 62 is set to 100 g / m ₂ or less, the hardness of the contact ball 62 itself becomes low, and handling in the packaging process becomes difficult. Further, when the basis weight of the contact ball 62 is set to 800 g / m ₂ or more, there is a demerit that the cost of the contact ball is increased.
(Example)
1) An example in which the moisture content of the contact ball 62 is defined by the above-described method for the thermal laser CTP using a contact ball 62 (100% waste paper) of 600 g / m ₂ is shown.

Next, when the relationship between the released water amount C and the sensitivity was measured and evaluated, it was found that if the released water amount was 2 g / m ₂ or less, the sensitivity was 100% or less, and a decrease in sensitivity could be prevented.

When the amount of water released is 2 g / m ₂ ,
2 = 600 × (A−B) / 100 (Expression 6)
It becomes. And according to (Equation 3)
B = 0.6385A + 2.4219 (Expression 7)
Substituting
2 = 600 × (A− (0.6385A + 2.4219)) / 100 (Equation 8)
Thus, A = 7.62% is obtained.

Next, the relative humidity (D) when A = 7.62% is the equilibrium moisture content is obtained from (Equation 1) obtained from FIG.
7.62 = 0.0996D + 2.0001 (formula 9)
Thus, D = 56.4% is obtained.

That is, in the case of the contact ball 600 g / m ² , it has been found that the use of the contact ball 62 having an equilibrium water content of 7.62% or less can prevent a decrease in sensitivity of the PS plate 10. Moreover, it turned out that the same effect is acquired by handling in an environment with relative humidity 56.4% or less.
2) An example in which the moisture content of the contact ball 62 is defined by the above-described method with respect to the thermal laser CTP using a contact ball 62 (100% waste paper) of 300 g / m ² is shown.

2 = 300 × (A−B) / 100 (Equation 10)
And
B = 0.6385A + 2.4219 (Equation 11)
Substituting
2 = 300 × (A− (0.6385A + 2.4219)) / 100 (Equation 12)
Thus, A = 8.54% is obtained.

And when substituting into (Equation 1),
8.54 = 0.0996D + 2.0001 (Formula 13)
Thus, D = 65.7% is obtained.

In other words, in the case of a contact ball of 300 g / m ² , it was found that a decrease in sensitivity of the PS plate 10 can be prevented by using the contact ball 62 having an equilibrium water content of 8.54% or less. Moreover, it turned out that the same effect is acquired by handling in an environment with a relative humidity of 65.7% or less.

  Thus, by selecting the contact ball 62 by the amount C of released water, the amount of water generated from the ball 62 is regulated accordingly. Thereby, the sensitivity fall of the application layer of PS plate 10 can be prevented.

  That is, since it is possible to prevent a decrease in sensitivity of the coating layer of the PS plate 10 without using the dried hitting ball 62, the step of drying the hitting ball 62 can be omitted. For this reason, cost reductions such as investment in air conditioning facilities and electricity costs can be achieved.

  Further, by lowering the weight of the contact ball 62, the contact ball 62 itself can be made inexpensive and the environmental humidity can be set high, so that costs such as electricity costs can be reduced. Furthermore, by setting the laser output value of the thermal laser to 100% or less, the lifetime of the thermal laser can be extended and the running cost can be reduced.

  Further, regarding the packaging of the PS plate 10, the lowering of the sensitivity of the coating layer of the PS plate 10 caused by direct contact or indirect contact between the contact ball 62 and the PS plate 10 can be solved. realizable. Moreover, it can also solve the environmental problems that have been a problem with hitting balls laminated with low density polyethylene that have been used conventionally.

  Furthermore, when the PS plate 10 is packaged with a shrink film, in the case of a low-density polyethylene laminated contact ball, there was a risk that the shrink film, the low-density polyethylene laminate and the contact ball were thermally welded. In this case, such a problem does not occur.

  In addition, this form is an Example to the last, and it cannot be overemphasized that it can change suitably in the range which does not deviate from the main point of this invention.

It is the schematic which shows the processing line of a lithographic printing plate. It is sectional drawing which shows the contact ball and laminated body which concern on embodiment of this invention. It is a graph which shows the correlation with relative humidity and the equilibrium moisture content of a contact ball. It is a graph which shows the correlation with relative humidity and the moisture content of the contact ball after a thermo process. It is a graph which shows the correlation with the equilibrium moisture content A of a contact ball, and the moisture content B of a contact ball. It is a graph which shows the correlation between a laser sensitivity and the amount of moisture discharge | released of a contact ball.

Explanation of symbols

10 PS plate (lithographic printing plate)
60 Laminate (lithographic printing plate)
62 Contact ball (protective material)
C Water released

Claims (2)

A method of selecting a protective material that is disposed at least on the top of a laminated lithographic printing plate, protects the lithographic printing plate, and is packaged together with the lithographic printing plate by a packaging material,
A protection material that selects a protective material with a water release amount that makes the laser sensitivity 100% or less based on a correlation between a laser sensitivity for exposing the lithographic printing plate and a water release amount released from the protective material. Material selection method. The method for selecting a protective material according to claim 1, wherein the relationship of the amount of water released C = basis weight of the applied ball M × (A−B) / 100 is satisfied.
Here, the amount C of released water is the amount of water released from the protective material, and A is a constant temperature and humidity chamber where the contact ball 62 is left for 240 hours at a temperature of 25 ° C. and a relative humidity of 30 to 70%. Measure the equilibrium moisture content of the protective material after conditioning to reach the equilibrium moisture content by the measurement method according to JIS P 8202, 8203. Correlation between the relative humidity and the equilibrium moisture content of the protection material in a temperature 25 ° C environment The equilibrium water content of the protective material obtained from the approximate expression obtained by the equation B is 48 in a state where the protective material adjusted to the equilibrium water content is packaged together with the planographic printing plate in a temperature of 45 ° C. and a relative humidity of 75%. Approximate formula obtained by correlating the relative humidity and the moisture content of the protective material at a temperature of 25 ° C. after measuring the moisture content of the protective material by measuring according to JIS P 8202 and 8203. Protected from This is the moisture content of the protective material.

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