JPH10272861A - Cylindrical blanket for printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable execution of stable printing for a long period, although this blanket has a relatively simple constitution. SOLUTION: A cylindrical blanket having a cylindrical sleeve 11 and a seamless cylindrical layer structure which is formed on the circumferential surface of the cylindrical sleeve 11 and has a compressive layer 13 and a surface elastic layer 15 formed thereon. A cylindrical elongation preventing layer 14 constituted of an elastic base 14a having short fibers 14b dispersed therein is provided immediately below the surface elastic layer 15. The short fibers 14b are arranged respectively in the circumferential direction substantially.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylindrical blanket for offset printing, and more particularly, to a cylindrical blanket used in so-called gapless printing or sleeve offset printing among offset printing.

[0002]

2. Description of the Related Art Conventionally, a blanket used for offset printing is generally in the form of a sheet. To attach the blanket to a blanket cylinder, the blanket is wound around the blanket cylinder, and both ends of the blanket cylinder are provided on the blanket cylinder. Need to be inserted into In a blanket cylinder equipped with such a sheet-like blanket, the blanket portion corresponding to the gap has a recess even if the gap is narrow, and the plate cylinder or the impression cylinder comes into contact with the recess. Since the printing press vibrates due to the impact at that time, it has been difficult to improve the printing speed. In addition, the blanket portion corresponding to the gap cannot be involved in printing, and is wasted.

In recent years, there has been proposed a cylindrical blanket which does not require a gap in a blanket cylinder for mounting (Japanese Patent Laid-Open Nos. 3-128247 and 5-30).
No. 1483, No. 5-138865, No. 6-3
Gapless printing or sleeve offset printing using this cylindrical blanket has been put to practical use.

[0004] This cylindrical blanket is basically
It has a structure in which a compressible layer made of sponge rubber or the like is formed around a cylindrical sleeve via an adhesive layer, and a surface rubber layer is formed thereon.

When the printing blanket is pressed against the plate cylinder in a state of being mounted on the blanket cylinder, the surface rubber layer is dented by the plate cylinder, and a bulge called a bulge is generated around the depression. This bulge is
In order to increase the effective circumference of the blanket, doubles and slurs occur in the printed matter. This phenomenon occurs irrespective of whether the blanket is sheet-shaped or cylindrical.

Therefore, in the case of a cylindrical blanket,
In order to minimize this phenomenon, a yarn having a diameter of 0.13 to 0.76 mm, preferably about 0.4 mm, is provided between the surface rubber layer and the compressible layer by a predetermined distance. It has been proposed to spirally wind at intervals (for example, see Japanese Patent Application Laid-Open No. Hei 5-301483). Since the wound yarn layer does not elongate itself, the elongation of the surface rubber layer can be prevented, and the occurrence of bulge can be suppressed.

However, in an offset printing press, the printing pressure is usually set to about 0.1 mm. Therefore, if a cylindrical blanket wound with a yarn having the above-mentioned thickness is used for a long time, the yarn becomes flat. As a result, unevenness occurs on the surface rubber layer, resulting in vertical streaks and transfer to printed matter.

That is, when winding a yarn, the yarn is first dipped in a rubber adhesive (rubber glue) and wound while fixing it on a blanket, but the rubber glue reaches the central portion of the yarn and is impregnated. In many cases, unpenetrated portions of rubber paste remain. In a blanket where the printing pressure is repeatedly applied several million times from the surface rubber layer side, the yarn is flattened due to the non-penetrated portion, so that the adjacent space between the yarns is narrowed, and the rubber existing there is The layer portion rises, and the surface rubber layer becomes uneven.

In order to solve this problem, it is necessary to sufficiently impregnate the yarn with rubber paste, but this requires a long residence time of the yarn in the rubber paste, which is not efficient. It is also conceivable to use a thinner thread. However, if a thinner thread is used, it takes a longer time to feed the thread when spirally winding the thread. If a plurality of yarns are wound together to avoid this, it is difficult not only to arrange the yarns uniformly along the circumferential direction, but also inconveniences such as overlapping of the yarns occur.

[0010] Furthermore, instead of winding the yarn, it is conceivable to wind a sheet of cloth, film, non-woven fabric or the like.
In this case, a seam occurs in the sheet, and a step occurs in the overlapping portion. It is also conceivable to cover with a plastic sleeve, but there are problems such as too hard and poor adhesion, which is not suitable for practical use.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned conventional problems, and provides a cylindrical blanket for printing that has a relatively simple structure and enables stable printing over a long period of time. The task is to

[0012]

In order to solve the above-mentioned problems, the present invention provides a cylindrical sleeve, a compressible layer formed on a circumferential surface of the cylindrical sleeve, and a surface formed thereon. A cylindrical layer structure having an elastic layer, wherein the cylindrical layer structure is made of an elastic material in which short fibers are dispersed between the compressible layer and the surface elastic layer, in contact with the surface elastic layer. A printing cylindrical blanket having a cylindrical anti-stretch layer, wherein the staple fibers are arranged substantially along a circumferential direction of the cylindrical sleeve.

Preferably, the short fibers have a length of 0.5 mm to 8 mm. The stretch-preventing layer preferably contains short fibers in a proportion of 2 to 15% by weight of the elastic substance. Further, the short fibers can be selected from cotton fibers, vinylon fibers, nylon fibers, polyester fibers, aromatic polyamide fibers, glass fibers, carbon fibers, alumina fibers, stainless steel fibers or mixtures thereof.

Further, according to the present invention, there is provided the above-mentioned method for producing a cylindrical blanket for printing, comprising forming a compressible layer on the cylindrical sleeve, and then rotating the cylindrical sleeve to form the elastic material precursor. A paste-like substance obtained by blending a solvent with a mixture containing short fibers and a short fiber is uniformly coated on the compressible layer by a doctor coat method so that the short fibers are arranged in a circumferential direction, and dried and stretched. A method for producing a cylindrical blanket for printing is provided, wherein a stop layer is formed and a surface elastic layer is formed thereon. The doctor blade to be used preferably has a rounded edge in order to prevent the fiber from being caught.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same parts and members are denoted by the same reference numerals. FIG. 1 is a perspective view showing a cylindrical blanket according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view (enlarged) taken along line II-II of FIG. As shown in these figures, the cylindrical blanket 10 of the present invention has the structure of an ordinary cylindrical blanket, except that an anti-stretch layer is interposed between the surface elastic (rubber) layer and the compressible layer. Have.

That is, the cylindrical blanket 10
Has a cylindrical sleeve 11 as a support for each layer, and a cylindrical layer structure including a compressible layer 13 and a surface rubber layer 15 is formed on the entire circumference of the cylindrical sleeve 11 in a seamless state to a uniform thickness. Have been. The cylindrical layer structure includes a compressible layer 13.
The stretch-preventing layer 14 formed between the surface rubber layer 15 and the surface rubber layer 15 is included immediately below the surface rubber layer 15. In the embodiment shown in FIGS. 1 and 2, the cylindrical layer structure has a cushion layer 12 in contact with a cylindrical sleeve 11.

In the present invention, the cylindrical sleeve 11 is
0.125mm ~ 0.15mm by metal such as nickel
It can be formed in the thickness of. In the present invention, the cushion layer 12 can be formed of various solid rubbers, and is particularly preferably formed of nitrile butadiene rubber (NBR). The cushion layer 12
May be omitted in some cases. Cushion layer 1
2 is 0.5 mm to 1.0 mm
It can be formed in the thickness of. This cushion layer 1
2 can be formed by an ordinary method such as a doctor coating method.

The compressible layer 1 is provided all around the cushion layer 12.
3 is formed in a uniform thickness. The compressible layer 13 is made of an elastic material, particularly a porous body of rubber such as NBR, and is usually called a sponge rubber layer. Compressible layer 13
Typically has a thickness of 0.2 mm to 0.4 mm. This compressible layer 13 can also be formed by an ordinary method such as a doctor coating method.

An anti-stretch layer 14 according to the present invention is formed over the entire circumference of the compressible layer 13 with a uniform thickness. The stretch-preventing layer 14 is formed by dispersing a large number of short fibers 14b in a solid elastic base material 14a made of a material having rubber elasticity, in particular, rubber such as NBR. It is substantially arranged in the circumferential direction of the cylindrical blanket. That is, as best shown in FIG. 2, each short fiber 14b extends in the circumferential direction.

The short fibers 14b are non-stretchable in the length direction and are not twisted by themselves. Suitable short fibers include cotton staple, vinylon staple, nylon staple, polyester staple, and aromatic polyamide staple (aramid staple) (typically, Teijin Conex, DuPont). Kevlar), glass short fiber, Tyranno short fiber (typically made by Ube Industries), alumina short fiber, stainless steel short fiber such as stainless steel short fiber (typically NASRON made by Nippon Seikon), etc. It is. Among them, cotton and vinylon short fiber are particularly preferable in consideration of adhesion to rubber, particularly NBR, difficulty in elongation, heat resistance, chemical resistance, strength, flexibility, ease of handling, cost, and the like.

The length of the short fiber 14b is desirably as long as possible without interfering with the formation of the elongation-stopping layer 14. In general, a short fiber having a length of about 0.5 mm to 8 mm can be used. . If it is longer than 8 mm, the short fibers may be entangled with each other and uniform dispersion in the stretch-preventing layer 14 and arrangement in the circumferential direction may not be achieved.

The thickness (diameter) of the short fiber is 0.02 to 0.
It is preferably 1 mm. By using such thin short fibers, flattening of the fibers due to printing pressure can be avoided.

Short fiber 14 blended in stretch-preventing layer 14
The amount of b is determined in consideration of the effect of preventing the surface rubber layer 15 from being stretched, the uniform dispersion and the arrangement in the circumferential direction in the layer 14, and the uniformity of the coating. That is, if the amount of the short fibers 14b is too small, the elongation preventing effect is not sufficiently obtained, and if the amount is too large, the short fibers 14b are uniformly dispersed in the elongation preventing layer 14, and are arranged in the circumferential direction and uniform in coating. Not enough. Short fiber 14
The amount of b depends on the material and length of the short fiber, the composition of the rubber compound (a constituent material of the elastic base material 14a) described later, the amount of the solvent used for forming the elongation preventing layer 14, and the like. Although it cannot be specified unconditionally, a rubber compound (excluding the solvent), that is, a ratio of 2 to 15% by weight of the elastic base material 14a is preferable.

The thickness of the elongation-preventing layer 14 in which the short fibers 14b are uniformly dispersed in the elastic base material 14a is sufficient to exert a sufficient elongation-preventing effect without impairing the compression characteristics of the compressible layer 13. Have. If the thickness of the stretch-preventing layer 14 is too large, the compression characteristics of the compressible layer 13 located thereunder are attenuated. If the thickness is too thin, a sufficient stretch-preventing effect cannot be obtained. This thickness depends on the material and length of the short fiber 14b,
Since it depends on the blending amount and the like, it cannot be specified unconditionally,
It is preferably within a range of 1 to 0.4 mm.

The stretch-preventing layer 14 can be formed as follows. That is, first, while rotating the cylindrical sleeve 11 in which the cushion layer 12 and the compressible layer 13 are formed on the cylindrical sleeve 11, a predetermined rubber paste substance is applied by a doctor coating method. More specifically, as shown in FIG. 3, while rotating the cylindrical sleeve 11 on which the cushion layer and the compressible layer are formed in the direction indicated by the arrow,
2 to apply. By this application, the short fibers 14b in the pasty substance 31 are arranged in the circumferential direction. The doctor blade 32 to be used preferably has a rounded coating edge. For example, as shown in FIG.
The edge portion 32a is bent to the side opposite to the side in contact with the rubber paste-like substance to form a curved surface, or as shown in FIG. Can be provided. By using a doctor blade having such a rounded edge, even if the dispersion of the short fibers in the rubber paste-like substance 31 is uneven, or even if the viscosity is uneven, the uniform The stretch-preventing layer 14 can be formed,
It was found that the short fibers could be arranged along the circumferential direction.

The pasty substance is converted into an elastic substance by vulcanization or the like, and a solvent such as toluene or methyl ethyl ketone is mixed with an elastic substance precursor (generally used rubber compound) for forming the elastic base material 14a. It is made into a paste form, and is prepared by blending short fibers in the above ratio.
In order to achieve good uniformity of application and good alignment of short fibers in the circumferential direction, the viscosity of the rubber paste is
Preferably 50 to 50 poise,
The amount of solvent can range from 250% to 30% of the weight of the rubber compound.
It is desirable to set it to about 0%.

Referring again to FIGS. 1 and 2, after forming the elongation preventing layer 14 as described above, the surface elastic (rubber) layer 15 as the uppermost layer is formed. This surface rubber layer 15 usually has a thickness of 0.2 to 0.4 mm,
It can be formed by a conventional method such as a doctor coating method.

In the cylindrical blanket having the above-described structure, the elongation preventing layer 14 effectively prevents the surface rubber layer 15 from elongating due to the printing pressure applied by the plate cylinder or the like. That is, a large number of short fibers arranged substantially in the circumferential direction in the stretch-stopping layer 14 do not stretch themselves, so that the stretch-stopping layer 14 is prevented from stretching, thereby preventing the surface rubber layer 15 from stretching. I do. Thus, the cylindrical blanket of the present invention can prevent the occurrence of a bulge in the surface rubber layer and provide a high-quality printed product free of doubles, slurs, and the like for a long period of time.

FIG. 6 shows a cylindrical blanket according to a second embodiment of the present invention, and is a cross-sectional view corresponding to a cross section orthogonal to the cross section of FIG. 1 and 2 except that a cylindrical blanket 60 has a non-stretchable layer 61 formed of a wound yarn 62 and adjacent yarns joined by a rubber 63 on the entire peripheral surface of the compressible layer 13. It has the same structure as the cylindrical blanket 10 described with reference to FIG.

The cylindrical blanket 60 shown in FIG. 6 can be manufactured by the same method as the cylindrical blanket 10 except for the non-stretchable layer 61. Non-stretchable layer 61
Is formed by dipping a yarn having a diameter of, for example, 0.2 to 0.3 mm in a rubber compound, winding the yarn around the compressible layer 13 and heating and vulcanizing the rubber compound in accordance with the known method. Can be. By providing such a non-stretchable layer 61, the stretch-preventing layer 1
In combination with the presence of No. 4, it is possible to provide an even more stable printed matter free of doubles and slurs for a long period of time.

[0031]

The present invention will be described below with reference to examples. Example 1 In this example, a cylindrical blanket having the same structure as that described with reference to FIGS. 1 and 2 was manufactured. That is, an NBR solid rubber layer having a hardness of 60 ° is formed as a cushion layer 12 on a nickel sleeve 11 having an outer diameter of 170 mm, and an NBR sponge rubber layer 13 is formed thereon as a compressible layer, and these are vulcanized. Polished. On the other hand, a rubber compound having the composition shown in Table 1 below was prepared, and toluene was added thereto to prepare a pasty substance.
mm, a vinylon short fiber having a diameter of 0.02 mm was mixed at a ratio of 3% by weight with respect to 100 parts by weight of the rubber compound.
This mixture was applied by a doctor coat method to a thickness after drying of 0.3 mm as described with reference to FIG. 3 and dried. At this time, the main shaft rotation speed of the blanket cylinder was set to 25 rotations / minute, and the coating was completed in 20 minutes. A rubber paste for forming a surface layer was similarly coated on the anti-stretch layer thus obtained to a thickness of 0.5 mm, vulcanized, and polished to a thickness of 0.3 mm. Thus, a cylindrical blanket having an outer diameter of 174 mm and a surface length of 910 mm was obtained.

Table 1 Ingredients Compounding amount (parts by weight) NBR JSR N232S 100 (Nitrile / butadiene rubber manufactured by Nippon Synthetic Rubber) Zinc Hua No. 1 5 (Zinc oxide) Sulfur 2 Succinol DM 1.5 (Vulcanization acceleration manufactured by Sumitomo Chemical Co., Ltd.) Nocrack SP 2.0 (Ouchi Shinko Chemical anti-aging agent) Celite 505 40 (filler: diatomaceous earth manufactured by Johns-Manville) Hysil 233 15 (reinforcing agent: hydrous silica manufactured by Pittsburgh Plate Glass) titanium white 5 (Colorant: titanium oxide) Example 2 After forming the compressible layer and before forming the elongation-preventing layer, the diameter of the compressible layer was set at 0.
An outer diameter of 174 mm having the structure shown in FIG. 3 was obtained in the same manner as in Example 1, except that the yarn of 3 mm was wound at a feed pitch of 0.4 mm while being immersed in the rubber paste used in Example 1.
A cylindrical blanket having a surface length of 910 mm was obtained.

Comparative Example After a cushion layer and a compressible layer were formed on a nickel sleeve in the same manner as in Example 1, a 0.3 mm diameter yarn was immersed in the rubber paste used in Example 1 to form a 0.4 mm diameter yarn. It was wound uniformly at the feed pitch. Thereafter, a surface rubber layer was formed in the same manner as in Example 1 to obtain a cylindrical blanket.

Using the cylindrical blankets obtained in Examples 1 and 2 and Comparative Example, printing was performed with a gapless printing machine, and printing misalignment and uneven streaks and settling of the blanket were examined. The results are shown in Table 2 below.

Table 2 Example 1 Example 2 Comparative Example Misalignment after printing 100,000 copies 1.0 mm 0.7 mm 2.5 mm Straight streaks after printing 3 million copies None None Yes Settling after printing 3 million copies 0.03 mm 0 .05mm 0.06mm

[0036]

As described above, according to the present invention,
A printing cylindrical blanket that solves the conventional problems and enables stable printing over a long period of time with a relatively simple configuration is provided, and the manufacturing of the cylindrical blanket is easy.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a cylindrical blanket according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view for explaining the method for manufacturing a cylindrical blanket of the present invention.

FIG. 4 is a schematic perspective view showing a doctor blade used when manufacturing the cylindrical blanket of the present invention.

FIG. 5 is a schematic perspective view showing another doctor blade used in manufacturing the cylindrical blanket of the present invention.

FIG. 6 is a schematic sectional view showing a cylindrical blanket according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Cylindrical sleeve 12 ... Cushion layer 13 ... Compressible layer 14 ... Stretch preventing layer 14a ... Elastic base material 14b ... Short fiber 15 ... Surface rubber layer 32 ... Doctor blade 60 ... Non-stretchable layer

Claims (6)

[Claims] 1. A cylindrical layer comprising: a cylindrical sleeve; and a cylindrical layer structure formed on a circumferential surface of the cylindrical sleeve and having a compressible layer and a surface elastic layer formed thereon. The structure has, between the compressible layer and the surface elastic layer, a cylindrical anti-stretch layer made of an elastic material in which short fibers are dispersed in contact with the surface elastic layer, and the short fibers are substantially formed. A cylindrical blanket for printing, which is arranged along the circumferential direction of the cylindrical sleeve. 2. The printing blanket according to claim 1, wherein the short fibers have a length of 0.5 mm to 8 mm. 3. The stretch-preventing layer is made of 2 to 15 elastic materials.
3. The printing blanket according to claim 1, which comprises short fibers in a proportion of% by weight. 4. The short fiber is a cotton fiber, a vinylon fiber, a nylon fiber, a polyester fiber, an aromatic polyamide fiber,
The cylindrical blanket for printing according to any one of claims 1 to 3, comprising glass fiber, carbon fiber, alumina fiber, stainless steel fiber or a mixture thereof. 5. The method for producing a cylindrical blanket for printing according to claim 1, wherein after forming a compressible layer on the cylindrical sleeve, the elastic material precursor and the short fiber are rotated while rotating the cylindrical sleeve. The short fibers are arranged in a circumferential direction by uniformly applying a paste-like substance obtained by blending a solvent with the mixture containing the mixture on the compressible layer by a doctor coat method, and then drying this to form an anti-stretch layer. Forming a surface elastic layer thereon, a method for producing a cylindrical blanket for printing. 6. The method according to claim 5, wherein the paste-like substance is applied using a doctor blade having a rounded edge.