JP2607487B2 - Cylindrical sleeve of non-woven web material - Google Patents

Description

The present invention relates to a cover member of a humidifying roll used for printing, particularly for lithography. More specifically, the present invention relates to a cylindrical sleeve made of a nonwoven web material partially having special fibers. or,
The present invention also relates to a method for manufacturing a cylindrical sleeve which exhibits improved characteristics when used as a humidifying roll cover.

〔background〕

Lithographic printing involves the application of a humidified aqueous solution to a print plate to cover the background area of the blade and then apply an oil-based ink to this area to serve as an image area. The aqueous solution is generally delivered from the source to the print plate by a series of rolls, including an ink transfer roll and a waterform roll, as will be appreciated in the following detailed description of the invention. The aim is to apply a clean, abundant thin-film aqueous solution that is as economical and efficient as possible and continuous over the duration of the printing process cycle to the background area of the printing plate. This versatile purpose is accompanied by many inherently conflicting requirements, and there are a few obstacles to achieving it.

Since integral rolls are generally very expensive, the demands on efficiency and economy begin with providing an interchangeable surface for the humidifier rolls. The replaceable surface in the form of a roll cover must be sized so that it can be easily mounted on the roll and then properly attached to the roll despite the rotational or other deformation forces that occur during operation. This mounting and grasping problem has been addressed in the prior art, a typical of which is U.S. Pat.
3,180,115. This patent describes a roll cover member that includes an elastic thread to avoid the deficiencies of many auxiliary fixing devices such as adhesives and end ties used in the prior art. A related improvement in elastic humidifying roll covers is described in U.S. Pat. No. 4,043,142, which uses a knitted fabric that reduces the tendency of the fabric to create patterns in printed copies.

A continuous, uniform aqueous humidification film is important in achieving good quality printing. Film discontinuities or patterns can be caused by irregularities in the cover surface, and the basic design of the cover member (US Pat. No. 3,180,115)
U.S. Pat.No. 4,043,
No. 042) or distortion or wear of the cover member during use. Thus, the cover member must be of uniform abrasion to eliminate irregularities during use without inherent irregularities in the initial design. In addition, the cover member must have sufficient structural integrity to resist the deformation forces that occur during use. The problem of non-uniformity due to fluffy fibers occurs in the ragged and coarsely woven cotton fabric called molleton. The fibers tend to compress in the time required for the interruption period to reach a stable state such that uniformity is achieved.

As far as providing a clean humidifying film, there are at least two considerations in selecting a humidifying roll cover.
First, the roll cover member can be a source of contaminants in the form of scraped cotton or coarsely woven fibers. During the humidification process, the accumulation of waste cotton or coarse woven fibers on the print plate prevents ink application to the next plate, resulting in a loss of print quality. The second consideration is the problem of ink contamination of the roll cover member and the ability to remove ink from the cover. After the pressing process, a small amount of ink that cannot be ignored is returned to the ink reservoir, and the ink is transferred and adheres to the roll cover. Accordingly, the ease of cleaning the roll cover member for removing ink is an important measure for evaluating the usefulness of the cover. To give an example,
If the Moreton roll is soiled with ink residue, it is necessary to remove the entire roll device and wash the surface in a separate washing tank.
Removal and replacement of the Moreton cover also occurs when changing the color of the ink, as often required for monochrome printing. The cover, which is the object of the present invention, can be washed on the printing press and no replacement is required for changing the color of the ink.

U.S. Pat. Is soluble,
It consists of hydrophilic, irregularly-arranged fibers that have certain properties in terms of extensibility and dimensional stability during drying. Examples of such fibers include polyvinyl alcohol (PV
A) Fiber, polypyrrolidone, rayon, cotton, partially saponified cellulose acetate fiber and others. Soluble fixative fiber or resin (eg PV
A) As the ratio of hydrophilic fibers (for example, rayon) increases, the strength of the sleeve also increases, but the water retention capacity and permeability decrease. A cover member made of these fibers performs well as a humidifying (forming) roll, but if it has sufficient strength to maintain structural integrity over a long period of use, it can serve as an ink transfer roll. Moisture retention and permeability are insufficient for use.

The ability to obtain an abundant amount of humidified aqueous solution depends on the liquid holding characteristics of the roll cover member. Even if the actual liquid source is contained within the reservoir, the degree of control to humidify the background surface of the print plate lies in the effective function of the ink transfer roll. For this reason, the roll cover must have the ability to absorb moisture from the sump roll, retain sufficient moisture, and release a controlled amount of liquid to meet the requirements and provide sufficient moisture from the roll. .

U.S. Pat.No. 4,339,858 discloses a cover member for a humidifying roll comprising a cylindrical member having substantially uniform cross-sectional dimensions and having inner and outer concentric layers with the above-mentioned features, wherein the inner layer is The outer layer is made of a porous non-woven member having a water-permeable hydroscope-like shape with a porous smooth continuous surface made of hydrophilic irregularly arranged fibers. A cylindrical member having a first radial dimension when dry and a second radial dimension when humidified with a radially expanding force. Wherein the second radial dimension is greater than the first radial dimension, the cylindrical member can retain the second radial dimension by drying and the third radial dimension by re-humidifying, Dimension is the second radial direction Law smaller. The woven fabric of the inner layer is relatively expensive, and its use will
A Excessive migration of the adhesive is caused, resulting in a reduction in the strength of the outer layer.

(Summary of the Invention)

The present invention has both sufficient moisture holding capacity and strength,
An object of the present invention is to provide a cylindrical sleeve that can be used as a cover member of a humidifying roll.

The invention features a cylindrical sleeve of nonwoven web material consisting of partially hydrolyzed acrylic fibers and other hydrophilic fibers.

According to another aspect of the present invention, a synthetic cylinder comprising a nonwoven web material having at least one inner layer and at least one outer layer, the inner layer having partially hydrolyzed acrylic and other hydrophilic fibers. A sleeve is provided.

According to yet another aspect of the present invention, a method of manufacturing a cylindrical sleeve comprises: Immerse a nonwoven web with partially hydrolyzed alkali fibers and other hydrophilic fibers in water,
B. Winding the soaked web around a cylindrical base layer; c. Wrap the web with a woven tape that is tensioned in the circumferential direction; Subjecting the wrapped web to heat sufficient to form a durable sleeve.

The use of partially hydrolyzed acrylic fibers together with other hydrophilic fibers imparts increased strength, moisture absorption and permeability to the sleeve.

This is based on the discovery of an unexpected property of the partially hydrolyzed acrylic fiber by the present inventors, and the property and the reason will be described in detail later.

〔Example〕

FIG. 1 shows a typical humidification wheel train system, in which a humidified aqueous solution 1 placed in a dish box 3 is taken up by a delivery roll 5 and an ink transfer roll 7 provided with a composite roll cover 9.
Through the instantaneous contact between rolls 5 and 7. The reciprocation of the ink transfer roll 7 between the delivery roll 5 and the vibration roll 11 is controlled by a cam mechanism 13. The humidified aqueous solution is transferred to the cover 9 of the ink transfer roll 7.
Is transferred to a vibrating roll 11, and further sent to a water forming roll 15 having a cover 16, and finally sent to the surface of a print plate 17.

FIG. 2 shows details of the composite roll cover 9. It has a non-woven inner layer 19 made of partially hydrolyzed acrylic fibers and other hydrophilic fibers and a non-woven outer concentric layer 21 made of polyvinyl alcohol.

As is well known in the art, acrylic fibers are fabricated fibers such that the fiber former is any long-chain synthetic polymer comprising at least 85% by weight acrylonitrile. The partially hydrolyzed acrylic fibers of the present invention are preferably less than 50% per hydrolysis amount, more preferably 25% per hydrolysis amount. The fiber is preferably Lansil (L) obtained from Japan Explan Co., Ltd.
anseal) Core sheath hydrolyzed acrylic fibers such as F. The core sheath fibers are made by hydrolyzing the polyacrylonitrile fibers such that the fiber sheath is polyacrylate and the core is polyacrylonitrile.
These fibers are described as "superabsorbent" fibers. Applicants have discovered the unexpected properties of these fibers. When mixed in proper proportions with other fibers and processed under proper forming conditions, these fibers not only increase the water retention capacity, but also act as an adhesive and increase the strength of the sleeve. As can be seen from the micrographs of the sleeve of the present invention, the hydrolyzed portion of the acrylic fiber becomes sufficiently soft during processing that some polymeric material of the fiber flows and the adjacent hydrolyzed acrylic fiber and other nonwoven webs It makes it possible to form an adhesive between the fibers.

The nonwoven webs useful in the present invention preferably include only a small amount of hydrolyzed acrylic fibers and most other hydrophilic fibers, which may be adhesive fibers or otherwise. For example, it is preferred that 10% to 50% by weight of the hydrolyzed acrylic fiber, the balance being rayon or a mixture of rayon and polyvinyl alcohol.

A particularly preferred grade of other adhesive fibers for nonwoven webs is polyvinyl alcohol fiber, from about 0.5 denier to
It is a polyvinyl alcohol fiber having an average fiber length of 0.5 cm to 6 cm (preferably 1 cm to 4 cm) at 6 denier.
Polyvinyl alcohol fibers come in various grades depending on their solubility characteristics in hot water. The use of polyvinyl alcohol fibers improves the abrasion resistance of the roll cover, and the use of a high percentage (25-50%) of polyvinyl alcohol fibers is necessary for roll covers subjected to high abrasion forces. Other useful heat-soluble fibers, i.e., fibers that can adhere to each other under heat and pressure, with or without moisture, include polypyrrolidone fibers.

In general, it is preferred to incorporate additional hydrophilic fibers that are not necessarily thermally soluble into the nonwoven web. Cellulose fibers such as cotton, regenerated cellulose, viscose rayon, cellulose acetate rayon, and other rayons are also incorporated to alter the properties of the nonwoven web or sleeve, for example, to increase strength and hydrogroscopy properties. The saponified cellulose acetate fiber, in particular, the cellulose acetate fiber, which is saponified in a uniform state suitable for production and is 0.5 denier to 3 denier and 0.6
An average length of a single fiber of 4 cm to 5.1 cm (preferably 1.3 cm to 3.81 cm) in combination with up to 40 weight percent of hydrolyzed acrylic fiber is used in the humidifying roll cover according to the present invention. It provides a non-woven material that exhibits excellent properties when exposed.

The sleeve of the present invention, which does not contain polyvinyl alcohol (PVA) but has improved tensile strength and moisture absorption as compared to sleeves made from a nonwoven blend of PVA and rayon, has reduced abrasion resistance as compared to such sleeves. Thus, sleeves of the present invention that do not contain PVA fibers should be used only on humidifying rolls, such as in low speed offset printing presses, where the cover has been exposed to normal or low abrasion forces.

In another embodiment shown in FIG. 2, the sleeve of the present invention is used as the inner layer of a composite cover having excellent tensile strength and moisture absorption in conjunction with the outer layer of PVA and rayon, which exhibit excellent wear resistance. Is done. In particular, the sleeve of the present invention can be used in place of the inner knit layer of the composite sleeve described in U.S. Pat. No. 4,339,858. A sleeve comprising the sleeve of the present invention as the inner layer and a high wear sleeve as the outer layer is particularly useful as an ink transfer roll cover which receives a large abrasion force.

Nonwoven materials are generally described in U.S. Pat. No. 3,293,097, referenced herein.
No. 3,229,351. These patents describe the use of non-woven fibers that can be processed in a preliminary direction for humidifying roll covers. As already mentioned, the forming roll covers described in these patents show only a few lithographic printing machine ink transfer positions due to the lack of moisture retention capacity.

In a preferred forming method, a non-woven web consisting of rayon, polyvinyl alcohol fiber and acrylic fiber obtained by hydrolysis of the core sheath is air-laid pr.
ocess) (or cross wrapping carded web). The handling strength of the nonwoven web can be improved by drilling a needle or applying an extremely thin aqueous solution of polyvinyl alcohol resin and drying in an oven. These treatments do not affect the characteristics of the formed sleeve.

The web is dipped in water or a weakly acidic aqueous solution and formed or wrapped in several layers around a cylindrical metal mandrel. Oxidation of the saturated water to a pH value of 3 to 4 is advantageous to the handling strength of the nonwoven web by temporarily reducing the water absorption of the acrylic fibers by hydrolysis. Following formation, this can be re-established by neutralizing the sleeve on a weak aqueous basis.

The nonwoven web on the mandrel is wrapped with a wet, woven tape under tension to apply significant radial compression to the fibers. Preferably the tension should be about 20% of the original combined thickness with some layers.
Must be enough to compress to%. The wrapped web is then subjected to sufficient heat to cause the acrylic fibers to adhere to a predetermined limit. The sleeve temperature must rise to at least 105 ° C, while the sleeve is still wet for acceptable adhesion. Depending on the heating method and the temperature, the heating time can be as short as several minutes to as long as one hour. Following tape removal, the sleeve is sanded to remove tape marks, removed from the mandrel, soaked in a water or weakly aqueous base, then expanded and dried.

As described in U.S. Pat. No. 3,229,351, the cover 9 has a seamless surface weave and a seamless, coherent, porous, easily squeezed non-woven cylindrical structure. The fibers are preferably a. Is substantially insoluble at temperatures below about 37 ° C (100 ° F), preferably below 76 ° C (170 ° F); Preferably at least 3% in the longitudinal direction when moistened with moisture; c. It has dimensional stability when dried, and d. It is a fiber having a hydrophilic irregular arrangement such that when moisture is humidified, it contracts in the longitudinal direction from its expanded state.

The nonwoven web can be comprised of a single layer or multiple layers of nonwoven material.
The use of hydrophilic fibers and / or resins that exhibit heat and moisture solubility in conjunction with other hydrophilic fibers in the non-woven web and heat, or heat and moisture, can be applied to the multilayer material simultaneously. Appropriate pressure can be applied in the apparatus to bond the multiple layers of web together. Of course, the specific conditions of heat, humidity and pressure depend on the fiber and resin used.

Water absorption up to 50% greater than comparable sleeves without Lanseal F due to the use of low levels of hydrolyzed acrylic fibers and Lanseal F together with polyvinyl alcohol fibers in a single nonwoven web It has been found that a sleeve having the same strength can be obtained.

In the case of the implementation of a composite sleeve, the use of Lanseal F in a nonwoven web as a substitute for the woven inner layer described in U.S. Pat. No. 4,339,858 provides a retention force equivalent to up to twice as much moisture absorption and twice as much resistance. A wearable sleeve is obtained.

EXAMPLE Test Method Two bench tests are useful as screening tools to determine the suitability of a forming sleeve for a humidifying cover.

Moisture absorbency Dry swatches are weighed, immersed in water for 30 seconds, wet on a humidified sponge and weighed again. Moisture absorption is reported as a percentage of dry weight. Experience has shown that a water absorption of 40-75% is preferred for a humidifying (forming) sleeve, and an absorption of 75% or more is preferred for an ink transfer sleeve or a "reservoir" therein. This test is described in U.S. Pat. No. 4,339,858, incorporated herein by reference.

Force at 5% elongation Uniform size 2.54cm x 15.24cm (1 ")
× 6 ″) sample length piece was cut from “around the cylinder” and weighed in a dry state. The sample is thoroughly dry,
The specimen was clamped by a tensile tester and a tensile strain rate of 5% per minute was imposed. Force at 5% elongation is normalized to dry sleeve base weight of 300 g / m ^2. Applicants' experience indicates that the forming sleeve must have a "5% force" of at least about 17 N / cm if it must be used as a unitary sleeve. If a strong backing is required during the forming process, a "5% force" of at least about 13 N / cm must be allowed to withstand the shear forces during use.

Fiber Acrylic fiber is Lanseal F fiber available from Exlan Japan. The Lanseal F fibers in Examples 1, 3, 5, 7, 9 and 11 are 7d × 56 cm and Examples 2, 4, 6,
The 8, 10, 12, 13, 14 and 15 F fibers had a size of 2.6 d × 35 mm. The rayon fiber available from American Enka as F700 is 1.5d x 35mm and Claron VP from Kurashiki Rayon
The one available as B101 was also 1.5d x 35mm.

EXAMPLES 1-8 AND COMPARATIVE EXAMPLES AD The following first set of examples was prepared by dipping a nonwoven fiber backing in 1% acetic acid.
This was performed by wrapping around a 51.3 mm diameter hollow mandrel. The backing was packaged in wet woven nylon with sufficient tension to apply a standard pressure of 1.22 kg / cm ² (122 KPa). A thermocouple was inserted during the packaging. A bag of Scotch pac was taped around the mandrel (to keep the sleeve moist) and the mandrel was inserted into the furnace at the set temperature.
After the thermocouples had reached temperature stability for at least 2 hours, the bag was removed and the sleeve allowed to dry for at least 1 hour at the set temperature.

According to the results of the above tests, Lanseal begins to bond at a lower temperature than PVA, but the bonding efficiency with temperature increases slightly with PVA.

Examples 9 and 10 and Comparative Example E The following are slightly different forming methods. After applying a normal pressure of 1.22 kg / cm ² (122 KPa) by wrapping tape on the wet backing, steam was passed through the hollow mandrel for 10 minutes. Due to mandrel leakage, the maximum steam temperature was about 115 ° C and the maximum sleeve temperature was about 98 ° C.

The Lanseal backing described above does not adhere like the PVA backing, but exhibits excellent moisture absorption. By way of example, Lanseal F fibers must be exposed to high temperatures for extended periods of time to obtain good adhesion.

Examples 11 to 15 and Comparative Examples F to H Next, a hollow mandrel having a diameter of 52.8 mm was used as described below. The lap tape tension was controlled to give two different normal pressures. 160 ° C steam was passed through the mandrel for various times. Under these conditions, the sleeve temperature was close to 110 ° C, while the backing was still wet and 150 ° C after the backing had dried.

Examples G and 13 above demonstrate the advantage of using Lanseal fibers to obtain increased moisture absorption and strength in low adhesive fiber blends. Examples 14, 15 and Comparative Example H
As shown, the benefits obtained by using Lanseal F are diminished in high adhesive mixtures.

Example 16 As an example of a synthetic forming sleeve, a 60% (weight) fiber 700 rayon (1.5d × 3) in which a hollow mandrel of 52.8 mm diameter was wetted with 1% acetic acid in three layers of 80 g / m ² base weight web
8mm), 17% VPB101 Polyvinyl alcohol fiber 1.5d × 3
8 mm) and 23% Lanseal F fiber (7d × 56 mm). 115 g / m ² basis weight web of 54% fibers 700 and 46% VPB101PVA is wound on a multi-web given wet with 1% acetic acid. A wet woven nylon cured tape is placed on these webs at 1.03 kg / cm ² (103 KPa) perpendicular to the mandrel surface
Wound under sufficient tension to give The mandrel was internally heated for 7 minutes using steam below 6.10 kg / cm ² (610 KPa). After the cured tape was unwound, the drying sleeve was sanded with 100 grid sandpaper to remove the tape markings. The sleeve was removed from the mandrel, immersed in 0.1 N aqueous ammonia, expanded to a diameter of 55.1 mm, and dried in this expanded state. This synthetic sleeve is 93% suitable for ink transfer roller cover
It had a 30 second moisture absorption rate.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a humidifying device in a typical lithographic printing press, and FIG. 2 is a perspective view of a synthetic roll cover of the present invention with a part removed to show a lower structure. 9: Composite roll cover, 19: Inner layer of cover 9, 21
... The outer layer of the cover 9.

Claims (15)

(57) [Claims] 1. A cylindrical sleeve of a nonwoven web material composed of partially hydrolyzed acrylic fibers and other hydrophilic fibers. 2. A cylindrical sleeve according to claim 1, wherein said partially hydrolyzed acrylic fiber is an acrylic fiber having a core sheath hydrolyzed. 3. The sleeve of claim 2, wherein said partially hydrolyzed acrylic fibers have a denier of 1 to 9. 4. The sleeve of claim 1, wherein the nonwoven web has at least 10% by weight of a partially hydrolyzed acrylic fiber. 5. The sleeve of claim 1, wherein the nonwoven web has up to 50% by weight of partially hydrolyzed acrylic fibers. 6. The cylindrical sleeve of claim 5, further comprising cellulosic fibers. 7. The sleeve of claim 6, wherein said cellulosic fibers are saponified cellulose acetate fibers. 8. The sleeve of claim 4, wherein said nonwoven web further comprises another heat-fusible fiber. 9. The sleeve according to claim 8, wherein said another heat-soluble fiber is a polyvinyl alcohol fiber. 10. The sleeve according to claim 1, wherein the partially hydrolyzed fibers are per hydrolyzed volume.
A cylindrical sleeve that is less than 50%. 11. At least one inner layer and at least one inner layer
A synthetic cylindrical sleeve having two outer layers, said inner layer comprising a non-woven web material having partially hydrolyzed acrylic and other hydrophilic fibers. 12. The sleeve of claim 11, wherein said outer layer comprises a nonwoven web comprising polyvinyl alcohol. 13. A method for producing a cylindrical sleeve, comprising the steps of: (a) immersing a nonwoven web having partially hydrolyzed alkali fibers and other hydrophilic fibers in water; and (b) applying the immersed web to a cylindrical base layer. C) wrapping the web with a woven tape tensioned to a circumferential length, and d. Subjecting the wrapped web to heat sufficient to form a durable sleeve. 14. The method of claim 13 wherein heat is provided by holding said web at a temperature of at least 105 ° C. for at least 4 minutes. 15. The method of claim 13, wherein the total tension in the circumferential length is sufficient to compress the layer of the web to a thickness of at least 20% of its original thickness. One way.