JPS5849297A - Cover for damping roller of offset press - Google Patents

Abstract

PURPOSE:To obtain a cover capable of being used for a long period of time by a method wherein moisture and water absorbing nylon is used as warp and knitted in a cylindrical form, the thread being highly water absorbent and abrasion resistant and in addition provided with the property of strongly fit to the damping roller. CONSTITUTION:A cover for a damping roller, the cover being knitted in a cylindrical form (it is preferred that polyurethan fiber drafted twice as large as the ordinary one is used as ground yarn and water soluble PVA fiber as core thread and in addition the core thread is covered with other filament which is soluble in water or cotten yarn so as to fix the polyurethan fiber as particular thread and the like), and the cover being composed of moisture and water absorbing nylon as upper thread. EFFECT: Special thread being used as ground yarn and knitted in a cylindrical form, it can be strongly fitted to the roller. Since the warp is limited, it offers excellent water absorption and abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cover for a water rod roller of an offset printing press.

In an offset printing press, the water rod roller that supplies water to the plate surface is a rubber roller with a cylindrical cover attached to the outside, which absorbs water and applies it to the surface of the plate cylinder.

Conventionally, covers for water rod rollers (hereinafter simply referred to as water rod covers) have mainly been made of braided fibers such as cotton, and cylindrical molded products made of synthetic resin have also been proposed. It can be divided into

The former has been used for a long time and has excellent water absorption, but has the disadvantage of poor abrasion resistance. Moreover, the latter is still not sufficient in water absorption, and has not yet been put into practical use as widely as knitted articles made of fibers. In any case, it is expected that an excellent water bar cover will emerge for rotary printing machines, which have become extremely faster, in order to maintain an excellent water supply function and durability that can withstand long-term use.

The present invention was made as a result of intensive research under such circumstances, and takes advantage of the water absorbing properties of the fiber braided body.
Furthermore, the present invention provides a water rod cover that has a high degree of wear resistance that can withstand high speed and severe use, and furthermore has strong fitting properties to the roller shaft.

That is, the present invention is a cylindrical braided water rod cover, which is characterized in that hygroscopic or water-absorbing Neuron is used as the upper thread.

In the present invention, as the ground yarn forming the braided body, threads (filaments or spun yarns) of various fibers that are normally used for water rod covers can be used, but particularly preferred are polyurethane fibers drafted twice or more and water-soluble Nine special yarns are produced by using polyurethane fibers as a core yarn and covering this with other water-insoluble filaments or spun yarns to fix polyurethane fibers.

A cylindrical braided body using such yarn as the ground yarn is
By treating the water with water after attaching it to the roller and prior to use, it creates an extremely strong fit to the roller.

Next, an important point in the present invention is to use a water-absorbent or hygroscopic nylon filament or spun yarn as the needle thread. Usually, this is braided using other threads as the base thread.The nylon used as the upper thread must be water-absorbent or hygroscopic nylon (hereinafter simply referred to as water-absorbent nylon). This nylon differs from conventional nylon in that it has water absorbency comparable to that of cotton, and it also has high abrasion resistance, which is a characteristic of nylon. It is interesting that it exhibits excellent water supply performance and high durability against water.

In order to manufacture the water rod cover of the present invention, for example, strong human silk thread or non-acetalized polyvinyl alcohol fiber,
Alternatively, the special yarn described above is used as the ground yarn, and the above-mentioned water-absorbing nylon filament or spun yarn is used as the upper yarn to knit into a cylindrical shape using a circular knitting machine. Constituent conditions of the ground yarn are not particularly limited as compared to knitting conditions 1, and known means can be adopted, but it is extremely important to use water-absorbing nylon as the upper yarn.
Furthermore, when the above-mentioned special thread is used as the ground thread, it is strongly nipped against the water rod roller, so that the effect of the present invention as a water cover can be further enhanced.

Note that the pile may be shirred into a velpet shape.

Since the present invention is constructed as described above, it has excellent water absorbency and high abrasion resistance, and also fits strongly into the water rod roller without causing the cover to twist or bulge. It can be used in high-speed rotary printing machines to fully demonstrate its printing capacity, and can withstand long-term use, making it extremely effective as a cover for water rollers.

Claims (1)

[Claims] A cover for a water rod roller of an offset printing press, characterized in that it is formed of a set of cylindrical rollers and uses hygroscopic or water-absorbing nylon as the upper thread.