JPH11138763A - Printing ink roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll having a long lifetime, hardly generating a density unevenness, a density change and a mist of ink, hardly producing deformation by a nip pressure even in the case of using for a long period. SOLUTION: A rubber roll containing a nitrile rubber having a hardness of 25 to 60 deg. as a cover rubber has many V-shaped grooves of a shade line state with an angle of 30 to 80 deg. and 100 to 150 deg. with respect to an axial direction of the roll on a front surface of the rubber roll so that its surface roughness (Rz) is 100 to 250 μm, the V-shaped grooves are partly discontinuous, and an insulator part is formed on the surface of the roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing ink roll, and more particularly to an ink transfer roll having a large number of grooves on its surface.

[0002]

2. Description of the Related Art As a printing ink roll or ink roller (both are simply referred to as rolls in the present invention), they are used as fountain rolls, ink transfer rolls, rolls for applying ink to a plate cylinder, and the like. In a roll used for transferring ink between rolls or between a roll and a plate cylinder, it is known that the surface condition of the roll affects ink density, generation of ink mist, life of the roll, and the like. For example, a roll having only grooves parallel to the axial direction of the roll has insufficient ink supply in the roll rotation direction, while a roll having grooves only in the roll rotation direction has a problem with the roll axis. In addition to the insufficient supply of ink in the parallel direction, there is a problem that ink mist is easily generated, and the scattered mist adversely affects the environment. For the purpose of solving these problems, Japanese Patent Application Laid-Open No. Hei 6-239
No. 65 describes a printing roller having a concave portion in which the surface of the roller is roughened and communicated with a lattice type groove or an oblique line type groove. With such a printing roll, although excellent printability can be obtained in the early stage of use, printability deteriorates when used for a long period of time, and problems such as the life of the roll remain.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a roll having a long life span, with less unevenness of ink density, change in density and generation of mist, less deformation due to nip pressure even after long-term use. It is.

[0004]

Means for Solving the Problems The present inventors have determined the material, hardness, surface groove shape, depth, width, angle with respect to the roll axis direction, groove contact, presence / absence of a grooveless portion, and the like. As a result of the study, it was found that such a problem was solved and a printed matter having stable quality was obtained, and the present invention was completed.

That is, the first aspect of the present invention is that the hardness is 25 to 6
A rubber roll having a nitrile rubber of 0 ° as a cover rubber, wherein the surface of the rubber roll is 30 ° with respect to the axial direction of the roll.
It consists of a large number of diagonal V-shaped grooves at angles of -80 ° and 100-150 ° with a surface roughness (Rz) of 100-25.
The present invention relates to a printing ink roll having a thickness of 0 μm. A second aspect of the present invention is the first aspect of the present invention, in which the hardness of the nitrile rubber is 30 to 50 °, and the hatched grooves are at 45 to 75 ° and 105 to 135 ° with respect to the axial direction of the roll. The present invention relates to a printing ink roll. A third aspect of the present invention is the printing according to any one of the first to second aspects of the present invention, wherein the V-shaped groove is partially discontinuous and the island portion is formed on the roll surface. It relates to an ink roll for use.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing ink roll made of rubber. As the printing ink roll, a nitrile rubber which is a synthetic rubber of a butadiene-acrylonitrile copolymer system excellent in ink resistance is preferable.
As the nitrile rubber, hardness (JIS K-63 described later)
01) is preferably from 25 to 60 °, especially from 30 to 50 °. By using such a material, when the surface of the roll is roughened as in the present invention, there is little roll swelling or deterioration due to ink even when used for a long period of time, and the roll is less deformed by the nip pressure. can get. If the hardness of the nitrile rubber is less than 25 °, the roll has poor compression resistance, and if it exceeds 60 °, the ink supply tends to be insufficient.

[0007] In order to prevent unevenness in the density of the ink and a change in the density over time, the transfer of the ink between the rolls or to the plate cylinder is performed uniformly and well, and mist is generated when the roll rotates and transfers the ink. The roll surface must have a special surface in order to obtain a roll having a small roll length and a long roll life due to a small deformation of the roll due to the nip pressure even after long-term use. The ink roll of the present invention is obtained by roughening the surface of the roll to a surface as shown in FIG. In FIG. 2, the horizontal direction indicates the axial direction of the roll, and the oblique lines indicate V-shaped grooves. On the entire surface of the roll, a large number of V-shaped grooves are provided in an oblique manner so as to intersect. The groove is substantially V
It is necessary to be in the shape of a letter
In the letter shape, the roll is likely to be deformed by the nip pressure. The surface roughness of the roll by providing a large number of V-shaped grooves is 100 to 250 μm in terms of 10-point average roughness (Rz),
Preferably it is 130 to 230 μm. Surface roughness Rz
If it is less than 100 μm, the transfer of the ink becomes insufficient, and if it exceeds 250 μm, the roll is easily deformed by the nip pressure, and the life of the roll is shortened.

The groove having a V-shaped cross section extends linearly on the surface of the roll to form a long groove (referred to as a groove line), and the direction of the groove line is 30 to the axial direction of the roll. 80 ° and 100-150 °, preferably 45-75 ° and 105
It has an angle of about 135 °, and a large number of groove lines are provided crossing obliquely. The groove line is 0 with respect to the axial direction of the roll.
If it is less than 30 ° (or more than 150 ° to 180 °), ink transfer is good in the axial direction of the roll but insufficient in the circumferential direction, and as a result, shading tends to occur. If the groove line is more than 80 ° and less than 100 ° with respect to the axial direction of the roll, the supply of ink in the axial direction of the roll is insufficient, and the amount of ink mist scattered in the air is reduced. More.

In the present invention, the V-shaped groove is partially discontinuous, and the island portion is formed on the roll surface. There is no particular limitation on the length of the groove line, but the groove line is cut off in some places, forming a partially discontinuous portion, and as a result, an island portion is formed on the roll surface, and the nip is formed. The roll is hardly deformed by the pressure, and the life of the roll can be extended. Since the roll is originally made by polishing, a shallow groove of about 50 to 60 μm or less may exist on the surface of the island. The lines of the intersecting grooves are not entirely connected,
The ink is sufficiently supplied both in the lateral direction and in the circumferential direction of the roll, and the formation of mist is suppressed.

In order to form a groove having the above-described structure on the roll surface, a specific grinding tool is used, and the tip of an abrasive is brought into contact with the roll surface to rotate the grinding tool. It is necessary to manufacture under the conditions. FIG. 1 shows a grinding tool used in the present invention. FIG. 1A is a view of the grinding tool 1 as viewed from a surface contacting a roll. The grinding tool 1 is annular, and 2 is a grinding surface, which is a rotating body in which the abrasive 3 is regularly implanted in a band shape on the plane side of the annular. Reference numeral 7 denotes a shaft hole of the grinding tool, which is attached to a rotary shaft of the grinder. FIG. 1B shows a part of a state where the abrasive 3 is regularly implanted. The shape of the tip of the abrasive may be a cone or a pyramid as long as the nitrile rubber can be ground, but a pyramid is preferred. The material of the abrasive may be a metal or an inorganic material having high hardness. As the rotating body, a disk shape, an annular shape,
Although hemispherical shape is mentioned, it is preferably an annular shape.

[0011] The length of the abrasive material is 100 degrees of V-shaped groove depth.
In order to form a layer having a thickness of about 250 μm, it may be 100 μm or more, and usually 0.5 to 5 mm. The lengths of the abrasives may be slightly irregular. The taper angle of the abrasive is selected to be suitable for grinding in contact with a roll to form the depth and width of the groove. In order to form a large number of diagonal grooves on the roll, the diameter of the ring and the density of the grinding material are determined by the roll diameter, the groove interval, the rotation speed of the roll, the rotation speed of the grinding tool, the translation of the grinding tool (traverse movement). ) Selected in consideration of speed. For example, the diameter of the ring is about 1/10 to 10 times the diameter of the roll, and the width of the plane part of the ring is 10 to 10 times.
At 100 mm, the density of the abrasive can be ² to 50 lines / cm ² . In the case of a grinding tool having a grinding material in the plane portion of the ring, the traversing of the grinding tool is performed once in one direction, and the intersecting grooves can be formed at one time. However, the grooves may be formed by a method of traversing a plurality of times by adjusting the abrasive density.

[0012] Alternatively, it is also possible to use a grinding tool having the same abrasive as that described above in the outer peripheral portion of the ring. In this case, traverse in one direction and traverse in the opposite direction are performed at least once each. Thereby, the intersecting grooves can be formed.

The length direction of the groove is 3 with respect to the axial direction of the roll.
To provide at angles of 0-80 ° and 100-150 °,
This is performed by adjusting the rotation speed of the roll, the rotation speed of the grinding tool, and the traverse speed of the grinding tool.

Using a grinding tool in which a large number of abrasives are implanted, while rotating the grinding surface, the grinding surface is brought into contact with the rotating rubber roll, and the rubber roll is traversed, so that the distance between the rubber roll and the grinding surface is increased. Is vibrated, so that a V-shaped groove is formed linearly, and the groove line is interrupted to form an island portion. In order to form such an island portion, the change in the interval between the rubber roll and the grinding surface may be caused by self-excited vibration or may be applied by forced vibration from outside. Such a V-shaped groove is formed in a linear shape, and the line of the groove is interrupted to form a part that is partially discontinuous. By forming an island, deformation due to the nip pressure of the roll is suppressed. , Can extend the life of the roll.

[0015]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. The hardness of the rubber of the roll is determined by a spring hardness test (A type) in JIS K-6301. The surface roughness Rz is according to JIS B-0601.

[Example 1] A rubber roll having a surface roughness Rz of 5 to 10 was used as a cover rubber made of nitrile rubber having a hardness of 36 °.
μm, 151 mm in diameter. As shown in FIG. 1, the grinding tool has a circular shape with a diameter of 152 mm, and the width of the flat portion of the circular shape is 25 mm, and the band portion has a length of about 2 mm, a root thickness of about 2 mm, and a spacing of about 2. A large number of 5 mm, pyramid tungsten carbide abrasives are regularly embedded (grid size # 550). Rubber roll 100r
The grinding surface was pressed against a rubber roll while the grinding tool was rotated at 4,450 rpm and traversed in one direction at 690 mm / min to roughen the entire roll surface. As a result, the rubber roll has a V-shaped groove, the surface roughness Rz is 160 to 180 μm, and the direction of the groove line is 60 to 65 ° and 115 to 12 with respect to the roll axis direction.
Many oblique lines at an angle of 0 ° crossed each other, and the groove lines had portions interrupted at various places (see FIG. 2). When the rubber roll obtained in this way was used as an ink transfer roll and printing was performed, the ink density of the printed matter was sufficient, there was no ink unevenness, there was little occurrence of ink mist during printing, Further, the deformation of the rubber roll due to the nip pressure was small, and printing could be stably performed even when the rubber roll was used for 6 months.

[Comparative Example 1] By the method according to Example 1,
A roll having a rough surface having a surface roughness Rz of 50 to 60 μm and a number of oblique lines crossing the groove in the longitudinal direction at angles of 60 to 65 ° and 115 to 120 ° with respect to the roll axis direction was manufactured.
As a result of printing using this roll, the supply of ink became insufficient shortly after the start of use.

[Comparative Example 2] According to the method of Example 1,
Rolls having a rough surface having a surface roughness Rz of 140 to 150 μm and a large number of oblique lines crossing the groove length direction at an angle of 10 to 20 ° and 160 to 170 ° with respect to the roll axis direction were manufactured. As a result of printing using this roll, the supply of ink in the rotational direction was insufficient, and ink unevenness was observed.

[Comparative Example 3]
A roll having a rough surface having a surface roughness Rz of 140 to 150 μm and a number of oblique lines crossing the groove in the longitudinal direction at an angle of 83 to 88 ° and 92 to 97 ° with respect to the roll axis direction was manufactured.
As a result of printing using this roll, a large amount of ink mist was generated, and ink supply in the axial direction of the roll was insufficient, and ink unevenness was observed.

[0020]

According to the present invention, a roll having a long life can be obtained with less unevenness of ink density, change in density and generation of mist, less deformation due to nip pressure even after long-term use.

[Brief description of the drawings]

FIG. 1 is a view showing a grinding tool used in the present invention.

FIG. 2 is a schematic view showing the surface of a printing ink roll of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grinding tool 2 Grinding surface 3 Grinding material 4 V-shaped groove 5 Island part 7 Shaft hole

Claims (3)

[Claims] 1. A rubber roll using a nitrile rubber having a hardness of 25 to 60 ° as a cover rubber, wherein the surface of the rubber roll is 30 to 80 ° and 100 to 1 with respect to the axial direction of the roll.
An ink roll for printing comprising a large number of oblique V-shaped grooves having an angle of 50 ° and a surface roughness (Rz) of 100 to 250 μm. 2. The nitrile rubber has a hardness of 30 to 50 °,
The printing ink roll according to claim 1, wherein the hatched grooves are at an angle of 45 to 75 ° and 105 to 135 ° with respect to the axial direction of the roll. 3. The printing ink roll according to claim 1, wherein the V-shaped groove is partially discontinuous, and the island portion is formed on the roll surface.