Printing – Processes
Patent
1995-02-16
1997-01-28
Burr, Edgar S.
Printing
Processes
101147, B41M 700
Patent
active
055969305
DESCRIPTION:
BRIEF SUMMARY
This invention concerns a process and a device for moistening a moving web of printed and thermally dried material according to the generic portion of patent claims 1 and 13.
In processing flat materials, especially webs of material, it is often necessary to moisten the material that is being processed before performing another processing step. Remoistening is especially necessary when processing printed and then thermally dried printed materials such as webs of paper or fabric.
Webs of paper, for example, are printed at a high speed in rotary offset printing and then they are subjected to a thermal drying process in order to dry and set the printing inks. In doing so, the printed web of paper must be moistened before the final processing in order to assure the original paper moisture content and thus the elasticity and dimensional stability of the paper required for the final processing. This is necessary because dry paper is very brittle and breaks or tears easily when folded or cut. In addition, dry paper expands when it absorbs moisture from the atmosphere, leading to unattractive waviness of finished coated newspapers, etc. and irregular "growth" of the individual pages in the cut areas.
In a known process for moistening webs of material (German patent 3,115,958 C2), a web of material is subjected to a corona treatment before a moistening agent is applied to it in a moistening station. This treatment is supposed to create a number of adhesive centers to promote adhesion of the particles of moistening agent. A moistening bath or a spray device that is not described in further detail is used as the moistening station.
With a known device for moistening moving webs of material, especially webs of paper (German patent 3,823,739 A1), one side of the web of paper is passed by a continuous belt whose top side has a conductive coating to which a high voltage is applied. To form aerosols of the moistening agent, a conductive atomizer is provided on the other side of the web of paper at some distance from it. A strong electric field is created between the atomizer and the conductive coating, causing the aerosol particles to be polarized and then accelerated so they not only wet the web of paper but also penetrate into the pores of the paper.
A disadvantage of this known device is that for a relatively high output, it is necessary to work with a high voltage in the range of 50 kV, so the moistening device is very sensitive to fluctuations in atmospheric humidity, because if the atmospheric humidity is too high, spark discharges may occur and can damage the web of paper. in addition, expensive shielding measures must be provided as a safety measure. Another disadvantage is that this known device needs a relatively large amount of space, so it cannot be added subsequently to existing printing machines or other processing machines.
With another known device (German patent 4,021,296 A1), an applicator roll that is in turn wetted by a scoop roll that dips into the moistening agent must be used to apply the moistening agent to the web of material. In order to moisten a web of material, the applicator roll is pivoted toward a web of paper or other material in such a way that it deflects the web out of its path of conveyance. As a result, the web of material moving over the applicator roll rubs off the film of moistening agent.
Since the contact between the web of material and the applicator roll is not uniform with this device, a uniform and defined application of moistening agent is impossible.
With another device for applying moistening agent to a web of material (U.S. Pat. No. A 3,066,046), an applicator roll is provided with an applicator surface that consists of a fabric with a rubber coating on the reverse side. The driven applicator roll is clamped between a scoop roll that dips into a moistening agent bath and a pressure roll. The web of material to be moistened is preferably passed through the crimping area between the pressure roll and the applicator roll.
The uptake of moistening agent by the surface of the
REFERENCES:
patent: 3066046 (1962-11-01), Walton
patent: 3168037 (1965-02-01), Dahlgren
patent: 3198199 (1965-08-01), Schultz
patent: 3647525 (1972-03-01), Dahlgren
patent: 4092440 (1978-05-01), Wohr et al.
patent: 4219864 (1980-08-01), Grunenfelder et al.
Cernea Gunther
Keller Alfred
Burr Edgar S.
Nguyen Anthony H.
Weitmann & Konrad GmbH & Co.
LandOfFree
Process and device for moistening a moving printed then thermall does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process and device for moistening a moving printed then thermall, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and device for moistening a moving printed then thermall will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-936247