JPS61258794A - Water-swellable ducter roller - Google Patents

Abstract

PURPOSE:To enhance durability, provide water absorptivity and water retention property suitable for an offset press and facilitate handling, by using a material comprising a water-swellable high molecular weight substance uniformly dispersed in an elastomeric substance as a material for a ducter roller. CONSTITUTION:The elastomeric substance is preferably a butadiene-acrylonitrile copolymer, polychloroprene, polyisoprene or the like, which is excellent in oil resistance, durability, processability or the like. The water-swellable high molecular weight substance is a block copolymer having the linkage form of (hydrophobic polymer segment)-(hydrophilic segment)-(hydrophobic polymer segment), and is used in a amount of about 10-200pts.wt. per 100pts.wt. of the elastomeric substance. It is necessary that the elastomeric substance be finally cross-linked, and in the production, a cross-linking agent such as sulfur, magnesium oxide, zinc white and a sulfur-containing compound and, optionally, a vulcanization accelerator are incorporated into a raw material compound when required.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a water rod for supplying immersion water in an offset printing press.

(Prior art) In an offset printing machine, a water film is formed on the non-image area of the printing plate to repel ink, and water is supplied to the plate surface corresponding to the non-image area in order to avoid staining the non-image area. There is a need to.

Furthermore, this water film must be uniform and the amount of water must be controlled to an optimum level. In other words, it is necessary to control the amount of soaking water supplied to the plate surface depending on the plate material used, the properties of the ink, the paper, the area ratio of printed areas to non-printed areas, and other printing conditions. A water rod is used for supply.

BACKGROUND ART Conventionally, water sticks have been made of cotton or the like woven into a cylinder, or made by covering a rubber roll with a paper tube-shaped nonwoven fabric.

(Problem to be solved by the invention) Cylindrical woven materials such as cotton have a very high water retention capacity, but the fibers may fall off and stick to the printed surface, or the water retention capacity is so high that it cannot be soaked in water. There are drawbacks such as the inability to quickly regulate supply and poor durability.

Although paper tube-shaped nonwoven fabrics have improved the above problems, they do not have cushioning properties and have very little dimensional flexibility, so they require specialized rubber rolls with high precision, and the installation accuracy is also poor. There are problems that require careful attention.

As a result of intensive research in order to solve the above-mentioned drawbacks of the prior art, the present invention solves the above-mentioned prior art by using a rubber-like substance with a water-swellable polymer uniformly dispersed in the water rod. The present invention was completed based on the finding that the drawbacks were solved.

(Means for Solving the Problems) That is, the present invention provides a water-swellable water-swelling material characterized in that the main raw materials are a rubber-like substance and a water-swellable polymer uniformly distributed in the rubber-like substance. It's a stick.

To explain the present invention in detail, the rubbery substances that serve as the base material of the water rod of the present invention include natural rubber, polybutadidine, polyisoprene, polyisobutylene, butadiene-styrene copolymer, and isoprene-styrene copolymer. , butadiene-acrylonitrile copolymer, polychloroprene, ethylene propylene rubber, acrylic rubber, ethylene-vinyl acetate copolymer, silicone rubber, urethane rubber, etc., and any conventionally known rubbery substances can be used in the present invention. I can do it.

Particularly preferred rubber-like substances in the present invention are butadiene-acrylonitrile copolymers, polychloroprene, polyisoprene, etc., which are excellent in oil resistance, durability, processability, and the like.

The water-swellable polymers used in the present invention include those having anionic hydrophilic groups such as starch-sodium polyacrylate grafted products, saponified starch-polyacrylonitrile grafted products, cellulose-sodium polyacrylate, vinyl Alcohol = sodium (meth)acrylate-(meth)acrylic acid copolymer, crosslinked sodium poly(meth)acrylate, alkali neutralized product of crosslinked inbutylene-maleic anhydride copolymer, sodium salt of crosslinked carboxymethylcellulose, etc. are mentioned,
Examples of nonionic hydrophilic groups include crosslinked polyoxyethylene oxide, crosslinked polyoxyethylene chain-containing urethane resins, and any conventionally known ones can be used.

Particularly preferred water-swellable polymers include, for example, JP-A-54-
No. 47798, No. 54-83091, No. 54-839
No. 89, No. 54-87791, No. 54-108895
(Hydrophobic polymer segment) described in the publication, etc.
(Hydrophilic segment) - (Hydrophobic polymer segment)
It is a block copolymer with a bond type of . Among such block copolymers, preferred are those in which the hydrophilic group of the hydrophilic segment is an alkali metal salt of carboxylic acid or sulfonic acid.

A more preferable water-swellable polymer is, for example, disclosed in Japanese Patent Application Laid-Open No. 1986-
This is a crosslinked polyoxyethylene chain-containing urethane-based water-swellable polymer described in Japanese Patent No. 225115.

These preferred water-swellable polymers have excellent miscibility when dispersed in a rubber-like material, and exhibit sufficient water absorption and water retention properties even when dispersed in a rubber-like material.

In the present invention, the above-mentioned water-swellable polymers are preferably used at a ratio of about 10 to about 200 parts by weight per 100 parts by weight of the rubbery material as the raw material. Products with a high swelling power are available, but even if the amount used is less than 10 parts by weight, the degree of water swelling of the product water rod will be insufficient, and even with a low swelling power, the degree of water swelling will be insufficient if the amount used is less than 10 parts by weight. If it is used in an amount exceeding 1 part by weight, the resulting water stick will have insufficient physical strength.

Note that these water-swellable polymers can be used alone or as a mixture, but the above-mentioned crosslinked polyoxyethylene chain-containing urethane-based water-swellable polymer may be used alone or in combination with other water-swellable polymers. By using it in combination with a molecular substance, it is possible to sufficiently crosslink and exhibit sufficient water absorption swelling properties even for strong rubber-like substances, and also to increase the water absorption swelling rate. The amount used is preferably 5% by weight or more based on the total water-swellable polymer.

In addition, in the present invention, it is necessary that the rubber-like substance is ultimately crosslinked, and in the manufacturing method, known crosslinking agents such as sulfur, magnesium oxide, zinc white, and sulfur-containing compounds are added to the raw material compound. A vulcanization accelerator may be included depending on the conditions. These crosslinking agents and vulcanization accelerators may be used in conventionally customary amounts.

Furthermore, in order to increase water retention and cushioning properties, the entire water rod may be foamed using a conventionally known foaming agent.

The water rod of the Ikemizu invention optionally contains conventionally known rubber additives such as carbon black, various coloring pigments, ultraviolet absorbers, antioxidants, waxes, process oils, higher fatty acids, various fillers, extender pigments, etc. can do.

The raw materials constituting the water rod of the present invention are as described above, and other features of the water rod of the present invention will be further explained together with the manufacturing method thereof.

The water rod of the present invention is made by kneading and homogenizing the various necessary raw materials as described above in a predetermined composition using a roll or a Banbury mixer.
Then, it is molded into a desired shape by any method such as extrusion molding, press molding, calendar molding, etc. These cross-wire conditions and molding conditions may be conventionally used conditions.

The molded product may be used as it is as a water rod, but it is preferable to use one that has been immersed in charcoal water and has sufficiently absorbed and swelled. It does not expel water, has a suitable water retention ability, and has sufficient rubber strength and elasticity. ´ In the production of molded products, for example, a method is used in which the product is formed into a hollow cylindrical shape and an iron core is attached to it, a method in which the iron core is attached after water absorption and swelling, or a method in which uncrosslinked rubber is wound around the iron core and then crosslinked into a roll shape. There are methods such as using it as a water rod after absorbing water and swelling.

A preferred method is to mold it into a hollow cylindrical shape, absorb water and swell it, then attach it to an iron core.

The dimensions of the water rod of the present invention as described above vary depending on the size of the offset printing machine that uses it, but generally it is a round rod with a diameter of about 3 to 15 cm and a length of about 30".
It is about ZOOcm.

(Function/Effect) The water-swellable water stick of the present invention obtained as described above uses a crosslinked rubbery substance, so it has high rubber strength and elasticity. Even after absorbing water and swelling, the rubber does not lose its strength and elasticity, and is very durable. Furthermore, it has water absorption and water retention properties suitable for offset printing machines, and is easy to handle, solving the disadvantages of conventional water rods. It is something.

Next, the present invention will be explained in more detail with reference to Examples. In addition, parts and percentages in the text are based on weight unless otherwise specified.

Example 1 50 parts of polyisoprene, 50 parts of polybutadiene, 60 parts of a water-swellable polymer (Dicewell, manufactured by Dainichiseika Industries, water swelling degree of about 150 times), cross-linked polyoxyethylene chain-containing urethane-based highly water-swellable polymer Molecular substance (water swelling degree approximately 15 times) 40 parts, kaolin clay 30 parts, precipitated calcium carbonate 20 parts
part, surfactant 5 parts, stearic acid 1.5 parts, zinc white 5 parts
2.5 parts of sulfur and 1.5 parts of 0M vulcanization accelerator were kneaded with a roll, and then press vulcanized in a hollow cylindrical mold at 160° C. for 15 minutes.

When the obtained molded product was immersed in water for about 30 days, it absorbed about three times its own weight in water and swelled.

Cut off both cross sections of the water absorbing rubber and attach the iron core to it.
The polished surface has appropriate elasticity and strength as a water rod, and when offset printing was performed using this,
Water could be supplied uniformly to the plate surface, and the printing condition was good. Additionally, this product had excellent durability as a water stick.

Example 2 100 parts of chloroprene rubber, crosslinked polyoxyethylene chain-containing urethane water I! i1 Swelling polymer (water swelling degree approx. 2)
0x) 80 parts, kaolin clay 60 parts, surfactant 2
0 parts, stearic acid 0.5 parts, magnesium oxide 4 parts,
After kneading 5 parts of zinc white and 221 parts of a vulcanization accelerator with a roll, press vulcanization was performed at 170° C. for 10 minutes in the same manner as in Example 1.

When the obtained molded product was immersed in water for 20 days, the water absorption and swelling ratio was approximately 1.8 times its own weight.

When an iron core was attached to this and used as a water rod, offset printing with good print quality was achieved as in Example 1.

Example 3 100 parts of NBR (medium nitrile), cross-linked sodium polyacrylate (water-swellable polymer, degree of water swelling approximately 250 times)
100 parts, 10 parts of crosslinked polyoxyethylene chain-containing urethane water-swellable polymer (water swelling degree approximately 15 times), Black Sub 4
0 parts, 60 parts of kaolin clay, 10 parts of surfactant, 1.5 parts of stearic acid, 5 parts of zinc white, 0.5 parts of sulfur, 21 parts of vulcanization accelerator and TTZ part of vulcanization accelerator. After kneading, the mixture was molded in the same manner as in Example 1.

When the obtained molded product was immersed in hot water at 50° C. for 10 days, it weighed about 3.5 times its own weight.

When we attached an iron core to this and used it as a water rod, it had appropriate cushioning properties and strength as in Example 1. When offset printing was performed using this, the water supply to the plate surface was uniform, and the printing The condition was also good. Additionally, this product had excellent durability as a water stick.

Example 4 100 parts of chloroprene rubber (extrusion type), 100 parts of water-swellable polymer (Dicewell, manufactured by Dainichiseika Industries, water swelling degree of about 120 times), 30 parts of kaolin clay, 20 parts of carbon black , 10 parts of process oil, 10 parts of black sub
0.5 parts of stearic acid, 5 parts of zinc white, 4 parts of magnesium oxide, and 2 parts of vulcanization accelerator - EUR1 were kneaded with a roll, extruded into a hollow cylinder, and then mixed with UHF and H
Continuous vulcanization was performed at AV (180°C) to obtain a molded product.

After cutting this molded product, it was immersed in water for 30 days.
It absorbed about 3.5 times its own weight of water and swelled.

This product had appropriate elasticity and strength, and when used as a water rod, the offset printing condition was good as in Example 1.

Example 5 100 parts of chloroprene rubber, 150 parts of water-swellable polymer (Dicewell, manufactured by Dainichiseika Chemical Industry, water swelling degree of about 100 times)
1 part, 20 parts of a crosslinked polyoxyethylene chain-containing urethane water-swellable polymer (water swelling degree approximately 15 times), 50 parts of kaolin clay, 30 parts of precipitated calcium carbonate, 15 parts of process oil, 0.5 parts of stearic acid part, blowing agent DPTS part,
5 parts of urea foaming aid, 4 parts of magnesium oxide, 5 parts of zinc white
parts, vulcanization accelerator -221 parts and vulcanization accelerator EUR1,
After kneading the two parts with a roll, extrude it into a hollow cylinder shape and form HAV
Continuous foam vulcanization is performed at 180℃, and the porosity is approximately 20%.
A molded product was obtained.

When this molded product is cut and immersed in warm water at 50°C for 15 days, it absorbs about 4 times its own weight in water.

Ta.

This product had appropriate elasticity and strength, and when used as a water rod, the offset printing condition was good as in Example 1.

Example 6 100 parts of NBR (medium high nitrile), water-swellable polymer (
Dicewell, manufactured by Dainichiseika Kogyo, water swelling rate approximately 120 times)
20 parts, 50 parts of crosslinked polyoxyethylene chain-containing urethane water-swellable polymer (water swelling degree approximately 15 times), Black Sub 10
1 part, 20 parts of kaolin clay, 2 parts of precipitated calcium carbonate
0 parts, 10 parts of surfactant, 1.5 parts of stearic acid, and press vulcanization for 5 minutes to obtain a cylindrical molded product with an iron core.

When this material was soaked in warm water at 50°C for about 30 days,
It absorbed water and swelled to about twice its own weight.

A material with both cross sections cut off and the surface polished has appropriate elasticity and strength as a water rod, and when offset printing was performed using this, the water supply to the plate surface was uniform and the printing condition was good. Met.

This product also had excellent durability as a water stick.

Example 7 [-Oka Yuunichloroprene rubber 100 parts Water-swellable polymer (Dicewell, manufactured by Dainichiseika Chemical Industries, water swelling degree approximately 120 times) 20 parts Urethane-based water-swellable polymer containing crosslinked polyoxyethylene chains material (water swelling degree approximately 15 times) 100 parts clay 4
0 parts black sub 50 parts stearic acid 0.5 parts surfactant
15 parts magnesium oxide
4 parts zinc white
5 parts Vulcanization accelerator - 220, 8 parts Yuyu 5BR 1502 100 parts Precipitated calcium carbonate 210 parts Carbon black 10 parts Process oil
20 parts stearic acid
2 parts zinc white
5 parts sulfur 2.5
Part vulcanization accelerator - DM 0, 8 parts After applying adhesive to the iron core, the above formulation (1 part) was made into a sheet form.
) Wrap the compound around the iron core to an outer diameter of 65 mm while applying pressure to prevent air from entering. Next, wrap the compound of formulation (2) over it, and heat it in a vulcanizer for 1 hour at a steam pressure of 5 to 8.
Vulcanize for 5 minutes. By polishing the vulcanizate, the rubber part of formulation (2) is removed. When this material is immersed in warm water at 50°C for 20 days, it absorbs water and swells to an outer diameter of 62 mm.
The one was changed to 66mm.

This material was polished to 64 mm to give a smooth surface. This water-absorbing and swelling material has appropriate elasticity and strength as a water rod, and when offset printing is performed using this material,
Water was supplied uniformly to the plate surface, and the printing condition was good. This product also had excellent durability as a water stick.

Claims (5)

[Claims] (1) A water-swellable water rod characterized in that the main raw materials are a rubber-like substance and a water-swellable polymer uniformly distributed in the rubber-like substance. (2) The water rod according to claim (1), wherein the hydrophilic group of the water-swellable polymer is anionic. (3) The water rod according to claim (1), wherein the hydrophilic group of the water-swellable polymer is of a nonionic type or a combination of a nonionic type and an anionic type. (4) The water-swellable polymer has at least one
The water rod according to claim 1, which is a block or graft copolymer having a (hydrophobic polymer segment)-(hydrophilic segment)-(hydrophobic polymer segment) bonding format. (5) Claim No. 1, wherein the nonionic water-swellable polymer is a urethane-based material containing a crosslinked polyoxyethylene chain.
) The water stick mentioned in section.