JP2015214042A - Blanket for surface conditioning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blanket for a surface conditioning roll capable of more stable surface conditioning.SOLUTION: A compression rigidity S in the thickness direction satisfies inequality: PS≥0.0049e(PS:compression stress, PL:amount of compression), and a surface free energy E of a surface on one side is 23 mN/m or less.

Description

  The present invention relates to a leveling blanket for leveling an ink surface printed on a printing medium before curing in an offset printing process.

In the printing process of offset printing, the surface of the ink printed on the substrate by the blanket cylinder is leveled with a leveling roll before curing to arrange the leveling process to reduce the unevenness of the ink surface, and printing A technique for improving the glossiness of the toner is known.
An offset printing machine provided with such a leveling roll is described in Patent Document 1, for example.

  Patent Document 1 is equipped with an elastic layer formed as a blanket on the outer periphery of the leveling roll, and a high-rigidity layer formed with an aluminum layer outside the elastic layer, and a silicone layer on the outermost periphery. It is described that it is coated.

JP 2009-274432 A

By the way, in the leveling process using the leveling roll as described in Patent Document 1, the ink is pulled toward the leveling roll when there is a large amount of ink printed on the printing material, and edge picking is performed. May occur. Therefore, it is desired that more stable leveling can be achieved without the ink being pulled toward the leveling roll.
From the viewpoint of handling, it is desired that a blanket alone attached to the leveling roll is provided with a configuration capable of stable leveling without providing a layer outside the blanket.

  Therefore, a problem to be solved by the present invention is to provide a blanket for a leveling roll capable of more stable leveling.

In order to solve the above problems, the present invention has the following configurations 1) to 3).
1) The compression rigidity S in the thickness direction satisfies PS ≧ 0.0049e ^21.087PL (PS: compression stress, PL: compression amount), and the surface free energy E of one surface is 23 mN / m or less. It is a blanket for face.
2) The blanking blanket according to 1), wherein the material of the one surface is silicone rubber or PTFE.
3) The leveling blanket according to 2), which is formed in a multilayer structure including at least a sponge layer.

  According to the present invention, it is possible to obtain an effect that more stable surface adjustment is possible.

It is a graph for demonstrating the compression rigidity S of the blanket for leveling which concerns on embodiment of this invention. 3 is a graph for explaining a characteristic SB shown in FIG. 1. It is a fragmentary sectional view for demonstrating the blanket 1 which is Example 1 of the leveling blanket of this invention. It is a figure equivalent to sectional drawing for demonstrating the leveling roll body 11 which mounted | wore the leveling roll 10 with the blanket 1. FIG. It is a partial schematic diagram for demonstrating the offset printing machine 21 provided with the leveling roll body 11. FIG. It is a fragmentary sectional view for demonstrating the blanket 31 which is Example 2 of the leveling blanket of this invention. It is a figure equivalent to sectional drawing for demonstrating the leveling roll body 131 which mounted | wore the leveling roll 10 with the blanket 31. FIG. It is a table | surface for demonstrating the experimental content and experimental result of a surface treatment.

  The leveling blanket of the present invention has a compression rigidity S higher than a predetermined characteristic (hard as compression feel), and free surface of the outermost surface that contacts the surface of the uncured ink K printed on the printing substrate. The energy E is set to a predetermined value Ea or less.

First, the compression rigidity S will be described with reference to FIG.
FIG. 1 is a graph showing the relationship between the amount of compression in the thickness direction and the compressive stress in a leveling blanket. In this graph, the horizontal axis represents the compression amount PL (mm), and the vertical axis represents the compression stress PS (kN / cm ² ).
As will be described later, the leveling blanket is formed in a multilayer structure including a sponge layer, and the compression rigidity S can be adjusted mainly by the material of the sponge layer.
FIG. 1 shows the characteristics of three types of blankets A, B, and C having different compressive rigidity S in three stages of large and small (in order of characteristic SA, characteristic SB, and characteristic SC in descending order of rigidity). In FIG. 1, a plurality of individual data are described for each characteristic.

The difference between the three types is, for example, about 0.09 to 0.10 mm in the characteristic SA and 0.13 to 0 in the characteristic SB when viewed from the compression amount PL at which the compressive stress PS becomes 0.1 kN / cm ^2. .14 mm, and the characteristic SC is 0.20 to 0.23 mm.
In terms of the compression amount PL at which the compressive stress PS is 0.4 kN / cm ² , the characteristic SA is generally 0.13 to 0.14 mm and the characteristic SB is 0.19 to 0.21 mm. The characteristic SC is 0.34 to 0.37 mm.

Each characteristic SA to SC draws a curve in which the increase of the compression stress PS with respect to the increase of the compression amount PL increases as the compression amount PL increases in the range where the compression stress PS is approximately 0.4 kN / cm ² or less.

As shown by the characteristics SA to SC, in the blankets A, B, and C, the blanket A is the hardest and the blanket C is the softest in terms of compression feel.
Here, the surface blanket of the present invention has a compression rigidity S that includes the characteristic SB and is larger than that.

FIG. 2 shows an actual measurement value having the smallest compression rigidity S among a plurality of specific actual measurement values of the characteristic SB and an approximate curve thereof.
In FIG. 2, the approximate curve is represented by (Equation 1).
(Equation 1)
PS = 0.0049e ^21.087PL
Therefore, the compression stiffness S of the surface blanket of the present invention is such that the compression stress PS is at least in the range of 0.05 to 0.55 kN / cm ² shown in FIG.
(Equation 2)
PS ≧ 0.0049e ^21.087PL
It satisfies.

On the other hand, for the surface free energy E, the predetermined value Ea is set to 23 mN / m.
That is, the surface blanket of the present invention has a surface free energy E of 23 mN / m or less on the surface brought into contact with the surface of the ink K.
The surface free energy E is dependent on the material, but the outermost material of the surface blanket is not limited as long as the surface free energy E on the outermost surface is 23 mN / m or less.

  As described above, the leveling blanket of the present invention has a compression rigidity S satisfying (Equation 2) and a surface free energy E on the outermost surface of 23 mN / m or less.

  A surface blanket according to the present invention will be described with reference to FIGS.

Example 1
A blanket 1 is a first embodiment of the leveling blanket of the present invention.
As shown in FIG. 3 which is a partial cross-sectional view of the blanket 1, a base layer 2 made of rubber and a sponge-like layer laminated on one surface side of the base layer 2 with a first base fabric layer 3 interposed therebetween. The sponge layer 4, the second base fabric layer 5 laminated on the sponge layer 4, the film 7 which is a resin film laminated on the second base fabric layer 5 via the adhesive layer 6, and the film 7 The surface rubber layer 8 has a multilayer structure.

The rubber forming the base layer 2 is, for example, NBR rubber.
The 1st base fabric layer 3 and the 2nd base fabric layer 5 are formed with the woven fabric formed including resin fibers, such as a nylon fiber and a polyester fiber, for example.
The sponge layer 4 is formed of a foam of rubber (for example, chloroprene rubber) or synthetic resin (for example, polyurethane).
The adhesive layer 6 is made of, for example, an acrylic adhesive.
The film 7 is, for example, a PET (polyethylene terephthalate) film.
The surface rubber layer 8 is formed of silicone rubber.
Each layer is integrally laminated by bonding.

As shown in FIG. 4, the blanket 1 is attached to the outer peripheral surface of a roll-shaped body 10 with the base layer 2 as the inner peripheral side. Therefore, the outermost peripheral surface becomes the surface rubber layer 8.
The body 10 with the blanket 1 attached thereto is referred to as a leveling roll body 11.
FIG. 4 corresponds to a cross-sectional view, and hatching is not given.

  The leveling roll body 11 is used by being attached to an offset printing machine 21 (hereinafter also simply referred to as a printing machine 21). FIG. 5 is a schematic diagram for explaining a main part of the printing machine 21.

The printing machine 21 includes a printing unit PB1 including a plate cylinder 22 and a blanket cylinder 23, and a pressure cylinder 24 that can be pressed against the blanket cylinder 23.
In the printing unit PB 1, water from the water roller 25 and ink K from the ink roller 26 are supplied to the plate cylinder 22. Then, the ink pattern corresponding to the plate of the plate cylinder 22 is transferred to the blanket cylinder 23 and further printed on the printing medium W conveyed between the blanket cylinder 23 and the impression cylinder 24. The to-be-printed body W is paper, a film, or the like.

Ink K is a UV curable type. The printing machine 21 includes a UV irradiator 27 as an ink curing unit PB2 on the downstream side in the transport direction from the printing unit PB1 in order to cure the ink K printed on the printing medium W.
The UV irradiator 27 irradiates the printed material W conveyed from the printing unit PB1 with a predetermined amount of ultraviolet light L1 to cure the printed ink K.

The printing machine 21 includes a leveling unit PB3 for leveling the surface of the uncured ink K printed on the printing medium W in the printing unit PB1 between the printing unit PB1 and the ink curing unit PB2. Yes.
The leveling section PB3 includes a leveling roll body 11 and a leveling pressure drum 28 that can be pressed against the leveling roll body 11. In the leveling section PB3, a predetermined pressure is applied in the thickness direction by the leveling roll body 11 to the ink K printed on the printing medium W conveyed from the printing section PB1.
Specifically, the surface rubber layer 8 of the blanket 1 of the leveling roll body 11 is in pressure contact with the surface Ka of the printed ink K.
As a result, the surface Ka of the ink K is reduced in surface roughness and becomes flatter than before pressure welding.

As described above, in the blanket 1 of Example 1, the surface rubber layer 8 brought into contact with the surface Ka of the ink K is formed of silicone rubber.
The surface free energy E on the surface of the surface rubber layer 8 made of silicone rubber can be obtained by measurement with a contact angle meter.
The surface free energy E is, for example, 13 mN / m 2, and the above-described predetermined value Ea = 23 mN / m or less.
In the blanket 1 of Example 1, the physical properties of the sponge layer 4 are adjusted, and the compression rigidity S satisfies (Equation 2).

  The thickness of each layer of the blanket 1 is not limited. That is, the ratio of the thickness of each layer shown in FIG. 3 is an example, and the ratio of the thickness of each layer in the blanket 1 is not limited.

(Example 2)
Example 2 is a blanket 31.
As shown in FIG. 6, which is a partial sectional view of the blanket 31, the first bottom base fabric layer 32, the first adhesive rubber layer 33 laminated on the one surface side, and the first adhesive rubber layer 33 are laminated. The second bottom base fabric layer 34, the sponge layer 35 stacked on the second bottom base fabric layer 34, the intermediate base fabric layer 36 stacked on the sponge layer 35, and the intermediate base fabric layer 36. An intermediate rubber layer 37 and a surface layer 39 laminated on the intermediate rubber layer 37 via a second adhesive rubber layer 38 are configured.

The 1st bottom base fabric layer 32, the 2nd bottom base fabric layer 34, and the intermediate | middle base fabric layer 36 are formed with the woven fabric formed including resin fibers, such as a nylon fiber and a polyester fiber, for example.
The sponge layer 35 is formed of a foam of rubber (such as chloroprene rubber) or a synthetic resin (polyurethane).
The intermediate rubber layer 37 is made of, for example, NBR rubber.
The first adhesive rubber layer 33 and the second adhesive rubber layer 38 have adhesiveness, for example, with NBR rubber as a main component.
The surface layer 39 is formed of a PTFE (polytetrafluoroethylene) sheet.
Each layer is integrally laminated by bonding.

As shown in FIG. 7, the blanket 31 is also attached to the outer periphery of the body 10 in the same manner as the blanket 1. At that time, the inner peripheral side becomes the first bottom base fabric layer 32, and the outer peripheral surface becomes the surface layer 39.
A body in which the blanket 31 is attached to the body 10 is referred to as a leveling roll body 131.
FIG. 7 corresponds to a cross-sectional view, and hatching is not given.

The leveling roll body 131 is attached to the printing machine 21 in the same manner as the leveling roll body 11, and the surface layer 39 of the blanket 31 is applied to the surface Ka of the uncured ink K printed by the printing unit PB1 of the printing machine 21. It comes to come in pressure contact.
As a result, the surface Ka of the ink K is reduced in surface roughness and becomes flatter than before pressure welding.

In the blanket 31 of the second embodiment, the surface layer 39 that is a portion in contact with the surface Ka of the ink K is PTFE.
The surface free energy E on the surface of the surface layer 39 made of PTFE is obtained by measurement with a contact angle meter.
The surface free energy E is, for example, 18 mN / m 2 and is not more than the predetermined value Ea = 23 mN / m described above.
In the blanket 31 of Example 2, the physical properties of the sponge layer 35 are adjusted, and the compression rigidity S satisfies (Equation 2).

  The thickness of each layer of the blanket 31 is not limited. That is, the ratio of the thickness of each layer shown in FIG. 6 is an example, and the ratio of the thickness of each layer in the blanket 31 is not limited.

  Next, the gloss improvement effect of printing by the blankets 1 and 31 of Example 1 and Example 2 will be described with reference to FIG. 8 showing experimental results.

In the experiment, first, six types of test blankets shown in FIG. 8 were prepared.
And the leveling roll body which attached each test blanket was mounted | worn to the printing machine 21 one by one, and the leveling process was performed on the printed uncured UV curable ink on the same conditions.
The surface treatment was evaluated comprehensively based on the glossiness of the print after ink curing and the stability of the printing state.
The evaluation results are given as ◎ (excellent), ○ (excellent), and Δ, in order from the better grade, ◎ and ○ are appropriate, and Δ is inappropriate.
In this experiment, the compression amount of the leveling roll body to which the blanket was attached was 0.13 mm.
The glossiness was evaluated visually. The stability was evaluated based on the presence / absence of edge picking depending on the amount of ink and the extent to which it occurred.

<Test blanket: See Fig. 8>
(Example blanket 1A, 1B)
Blanket 1A: The blanket of Example 1, in which the surface free energy E is 13 mN / m, and the compression rigidity S is adjusted to obtain the characteristic SA.
Blanket 1B: The blanket of Example 1, wherein the compression rigidity S is adjusted to the characteristic SB with respect to the blanket 1A.
Blanket 31A: The blanket of Example 2, wherein the surface free energy E is 18 mN / m, and the compression rigidity S is adjusted to obtain the characteristic SA.
Blanket 31B: The blanket of Example 2, wherein the compression rigidity S is adjusted to the characteristic SB with respect to the blanket 1A.

(Comparative blanket 101, 102)
Blanket 101: a first blanket for comparison, in which the outermost layer is an NBR rubber layer in order to make the surface free energy E higher than that in Example 2. The blanket 101 had a surface free energy E of 26 mN / m. Further, the compression rigidity S was adjusted to a characteristic SB.
Blanket 102: a second blanket for comparison, in which the compression stiffness S is significantly smaller than the characteristic SB (soft as a tactile sensation). Specifically, the compression stiffness S of the blanket 31B is adjusted to obtain a characteristic SC.

As shown in FIG. 8, the blanket 1 </ b> A was suitable for “excellent” in glossiness and stability and “excellent” in overall evaluation.
The blankets 1B, 31A, and 31B were suitable for “excellent” in at least one of glossiness and stability.
On the other hand, the blankets 101 and 102 of the comparative blanket were unsuitable for glossiness and stability, and were not suitable for comprehensive evaluation.

From this result, the surface blanket is improved not only in glossiness but also in stability by making the surface free energy E 18 mN / m or less and the compression rigidity S larger than the characteristic SB (hard as tactile sensation). It became clear.
Although not shown in FIG. 8, in a similar experiment, when the compression rigidity S satisfies (Equation 2), the overall evaluation is appropriate when the surface free energy E is 23 mN / m or less. .

These effects are exhibited regardless of the type of ink by setting the physical property values of both items of the compression rigidity S and the surface free energy E within the range of the surface blanket of the present invention.
Specifically, by setting the predetermined value Ea of the surface free energy E to 23 mN / m or less, ink repelling on the outer surface of the leveling blanket is improved, the separation of the pressed blanket is improved, and the leveling is improved. The surface is stable.

  Further, by satisfying (Equation 2) for the compression rigidity S, the ink behavior associated with the pressure contact is clearly different from the behavior on the blanket side even if the amount of printed ink is large. Therefore, the ink does not follow as it is picked up by the blanket, the ink separation is good, and the leveling is stabilized.

  As described above, the surface blanket has a compressive rigidity S satisfying (Equation 2) and a surface free energy E of the outermost surface of 23 mN / min without adding a layer or other treatment. When it is less than or equal to m, it is possible to stably perform leveling to improve printing gloss when used in the leveling step.

  The conditions on the printing machine 21 side are not particularly limited as long as the conditions are within a condition range in which leveling is possible. For example, the amount of compression of the blankets 1 and 31 in the leveling step is not limited, and includes the amount of compression 0.13 mm in the above-described experiment, for example, 0.05 mm to 0.20 mm.

  The embodiment of the present invention is not limited to the above-described configuration and procedure, and may be modified as long as it does not depart from the gist of the present invention.

As for the blanket 1, the material of the other layer is not limited as long as the material of the surface rubber layer 8 is silicone rubber.
As for the blanket 31, the material of the other layers is not limited as long as the material of the surface layer 39 is PTFE.
The blanket 1 does not necessarily include the sponge layer 4. Further, the blanket 31 does not necessarily include the sponge layer 35. In any case, it is only necessary that the compression stiffness S in the thickness direction satisfies (Equation 2).
Compression stiffness

1A, 1B blanket 2 base layer, 3 first base fabric layer, 4 sponge layer 5 second base fabric layer, 6 adhesive layer, 7 film, 8 surface rubber layer 10 body 11, 131 leveling roll body 21 (offset ) Printing machine 22 Plate cylinder, 23 Blanket cylinder, 24 Impression cylinder 25 Water roller, 26 Ink roller, 27 UV irradiator 28 Impression cylinder for leveling 31, 31A, 31B Blanket 32 First bottom base fabric layer, 33 First adhesion Rubber layer, 34 Second bottom base layer 35 Sponge layer, 36 Intermediate base layer, 37 Intermediate rubber layer 38 Second adhesive rubber layer, 39 Surface layer E Surface free energy, Ea Predetermined value K ink, Ka surface L1 Ultraviolet PB1 Printing section, PB2 ink curing section, PB3 leveling section S compression rigidity, SA to SC (of compression rigidity S) characteristics W substrate

Claims (3)

For surface flattening where the compression stiffness S in the thickness direction satisfies PS ≧ 0.0049e ^21.087PL (PS: compression stress, PL: compression amount), and the surface free energy E of one surface is 23 mN / m or less blanket.   2. The leveling blanket according to claim 1, wherein the material of the one surface is silicone rubber or PTFE.   The blanket for leveling according to claim 2, wherein the blanket is formed in a multilayer structure including at least a sponge layer.

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