JPS62282986A - Rubber blanket for offset printing - Google Patents

Abstract

PURPOSE:To perform uniform printing, by using a rubber blanket formed of base cloth having a structure consisting of a warp yarn comprising a high strength and low elongation polyvinyl alcohol long fiber and a weft yarn comprising one or more of a synthetic fiber, a regenerated fiber and a cotton fiber or by laminating a plurality of said base cloths and other base cloth and applying natural rubber to said base cloth or the laminated one as a topping layer. CONSTITUTION:A high strength and low elongation polyvinyl alcohol long fiber yarn is used as a warp yarn and one or more of a synthetic fiber such as a polyester fiber, a regenerated fiber such as a rayon fiber and a cotton yarn is used as a weft yarn to prepare base cloth for a blanket. This base cloth for the blanket is about 10 times in cutting strength and also low in tensile elongation at break as compared with conventional base cloth using a cotton yarn. A coating layer of natural rubber or synthetic rubber is provided to the single surface of the base cloth or a laminate consisting of a plurality of said base cloths and other base cloths. As a result, non-uniformity of a yarn thickness and yarn knots are absent and no weaving inferiority is generated and, therefore, the blanket has a uniform surface and uniform printing can be performed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a medium for transferring ink supplied onto a plate cylinder onto a printing medium such as paper in an offset printing machine. A rubber blanket (hereinafter referred to as a blanket) that plays the role of
It is related to.

[Conventional technology]

In general, an offset printing machine mainly consists of a plate cylinder having a plate surface, a blanket, and an impression cylinder.The blanket receives ink supplied onto the plate cylinder, and the ink is ink supplied between the blanket and the impression cylinder. Most of the materials were obtained by topping (coating) natural rubber or synthetic rubber on the base fabric.

[Problem that the invention seeks to solve]

However, since the cotton thread that is the material of the base fabric is obtained by spinning raw cotton obtained from cotton,
Not only do cotton scum exist and the thread thickness is uneven, but there are also quite a few knotted points during the production of cotton thread, and knotted points also occur during weaving, as well as uneven thread thickness. There are disadvantages such as poor weaving due to the weaving process, which causes unevenness on the blanket surface, which in turn causes uneven printing.Currently, corrective inspection is carried out by one person for a long time. Chiru. Although we are trying to stabilize the quality of weaving by manufacturing the required yarn count using this twisted yarn, it is still not sufficient, and the current focus is on removing defects by manual work.

Furthermore, offset printing has the advantage of being able to perform continuous high-speed operation by attaching a printing blanket to a cylinder, but due to continuous high-speed operation, the blanket may be distorted during operation. Distortion is directly linked to printing defects, so its elimination is required. The cause of this distortion is thought to be the elongation in the warp direction, and this has to do with the difficulty of attaching the blanket to the cylinder, but the residual elongation in the warp direction is 0.2-3% (300-300%). 1
000 at a load of 97 m).

In order to meet this requirement, conventional blanket base fabrics required fairly severe work.

In other words, the breaking elongation of a 20 count single cotton yarn is 6 to 7 inches, and when this is twisted and further made into a fabric, the breaking elongation increases to 14 to 15%. ), it was necessary to apply considerable force in the warp direction of the fabric and stretch it by about 10% to reduce the residual elongation. However, such harsh operations often damage the shape of the fabric, resulting in tears in the edges, holes in the center, and even breakage, which greatly reduces the product yield9. be.

[Means and effects for solving the problem] In view of the current situation, the present invention uses polyvinyl alcohol-based long fiber yarn with high strength and low elongation as the warp yarn, and uses one or more of synthetic fibers, recycled fibers, and cotton yarn as the weft yarn. By laminating multiple sheets of the base fabric obtained by weaving the base fabric alone or with other base fabrics, and topping (coating) with natural rubber or synthetic rubber, uneven thickness of the threads can be reduced. There are no knots or thread knots, so there are no weaving defects, so the bracket surface is uniform, and uniform printing is possible.In addition, because it has little shrinkage, it can eliminate the need for the conventional stretching process in the manufacturing process. The present invention will now be described in detail, providing a rubber blanket for printing.

The polyvinyl alcohol long fiber yarn used in the present invention is a long fiber yarn made of a polyvinyl alcohol resin mainly containing polyvinyl alcohol.

It has excellent smoothness and heat resistance, as well as high strength and low elongation. The polyvinyl alcohol long fibers used here are particularly required to have high tenacity and low elongation, and desirably have one strength of 11.5 to 15 g/d and elongation at break of 5 to 7%. Various finenesses are used, but 2
It is desirable that it be within the range of 00 to 1500 d.

Polyvinyl alcohol-based long fiber yarn is used for the warp to weave the base fabric for the blanket, while for the weft, one or more of synthetic fibers such as polyester and polyamide, recycled fibers such as rayon and acetate, and cotton yarn are used. The texture of the fabric may be of various types, but a flat texture is preferable.

Polyvinyl alcohol-based long fiber yarn is 11, for example 600.
In case of d, the cutting strength is 6000. ! i', the cutting elongation is 5-6%, and the cutting strength of the 20th twin yarn of the same thickness as the conventional material cotton yarn is 6005'.

While the cutting elongation is 7 to 8%, the cutting strength is 10 times greater and the cutting elongation is small. Therefore, in the case of a blanket base fabric woven using polyvinyl alcohol-based long fiber yarns of 600 dt-warp, the cutting strength in the warp direction is 135 to 150/cm, and the cutting elongation is 7 to 150/cm.
10%, and the cutting strength of the blanket base fabric woven using 20 count double yarn cotton yarn is 10 to 151 Cg/
m, cutting elongation is 12 to 15%, whereas the cutting strength is about 10 times lower, and the cutting elongation is also clearly smaller, indicating that the base fabric using polyvinyl alcohol long fiber yarn is superior. It is clear that

The base fabric for the blanket has a specified strength (10 kg/Crn or more) and elongation (3 to 10
0.2 to 3%) at 9/crn), the strength is 20 to 9/cm or more, and 20kg
It is required that the permissible elongation is 2 to 3% under a load of /cm, but this required property can be achieved in the base fabric using polyvinyl alcohol long fiber yarn as the warp and in the state before finishing processing. is satisfied, and there is no need to apply a strong stretching force to the base fabric after weaving it to reduce the residual shrinkage rate, unlike in the case of base fabrics using cotton yarn. In addition,
The permissible elongation required by the longitudinal tension applied during rewinding to adjust the texture of the fabric or during the next production of the blanket can be satisfied to a certain extent.

Next, a plurality of base fabrics using the polyvinyl alcohol-based long fiber yarns as warp threads are laminated together alone or together with other base fabrics. When bonding with another base fabric, it is desirable to use a base fabric in which polyvinyl alcohol-based long fiber yarn is used as the warp for at least one of the outermost layers. Although various adhesives can be used for bonding, liquid materials such as nitrile rubber and chloroprene rubber are preferable.

A coating layer of natural rubber or synthetic rubber is provided on one side of the laminate obtained in this way, but when the base fabric uses a polyvinyl alcohol long fiber yarn as the warp together with another base fabric. In this case, it is desirable to provide a topping layer (coating layer) of natural rubber or synthetic rubber on a base fabric whose warp is polyvinyl alcohol long fiber yarn used in at least one of the outermost layers. This is because the base fabric adjacent to the coated rubber layer has the greatest effect on the properties such as smoothness and non-shrinkage of the rubber layer, and if economy is required, inexpensive base fabrics can also be used. However, the method of use with other base fabrics is not limited to this, and various combinations are possible.As the synthetic rubber, nitrile rubber, chloroprene rubber, polyacrylate rubber, epichlorohydrin rubber, polysulfide rubber, etc. are preferable. These molten particles are topped (coated) and vulcanized to form a topping layer (coating layer).

〔Example〕

Polyvinyl alcohol-based long fiber yarn 600di warp (50
500 d of polyester long fiber yarns are woven into a flat weave (30 strands/inch) as wefts (30 strands/inch).
Winding work into a roll was carried out at a load of 500:9 per m width, which also served as adjustment of the texture of the fabric and preparation for the sizing process. The resulting fabric had a cutting strength of 13 kg 7 cm and a cutting elongation of 8%.
Met. Prepare four sheets of this fabric, first adhere two sheets together using a nitrile rubber adhesive, heat and vulcanize at 150°C, then attach the next sheet and heat vulcanize, and so on. A rubber blanket' was obtained by laminating the sheets together, and then repeatedly applying a nitrile rubber liquid to the surface about 100 times to form a topping layer having a thickness of about 500 ml, followed by heating and vulcanization.

Regarding the yield rate, the gray fabric pass rate for the base fabric is 95 yen.

The pass rate after the correction was 97.5%, and for the blanket it was 97%. In addition, for the base fabric when conventional cotton yarn was used, the gray fabric pass rate was 82%, the pass rate after correction was 87%, and for the blanket it was 82%.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, smooth, high strength, low elongation polyvinyl alcohol long fiber yarns soaked in heat resistance are used as warp yarns, so that the thickness of the yarns is uneven. , there are no yarn knots, no weaving defects, and therefore the blanket surface is uniform, which not only enables uniform printing, but also eliminates the need for the conventional stretching process, reducing costs. It has excellent practical effects such as low cost.

Claims (1)

[Claims] A base fabric obtained by weaving high-strength, low-elongation polyvinyl alcohol-based long-fiber yarns as warps and one or more of synthetic fibers, recycled fibers, and cotton yarns as wefts, either alone or in combination with other base fabrics. A rubber blanket for offset printing that is made by laminating sheets and topping (coating) them with natural rubber or synthetic rubber.