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Title:
DAMPING SOLUTION ADDITIVE FOR OFFSET PRINTING MACHINES
Document Type and Number:
WIPO Patent Application WO/2012/052157
Kind Code:
A1
Abstract:
In a process for modifying a damping solution of an offset printing machine, a mixture of an alcohol selected from a monobutyl ether of mono-, di- or triethylene glycol, monobutyl ether of mono-, di- or tripropylene glycol, 2-methylpentane-2,4- diol (hexylene glycol) and 2-ethylhexanol (isooctyl alcohol), or a mixture thereof, and an acetic or propionic ester with any one of same alcohols or a mixture of such esters in a ratio of about 40-60:about 15-25 parts by volume is introduced in such an amount into the damping solution preparation unit of the offset printing machine that the total concentration of the mixture in the damping solution of the damping solution circuit is about 0.1% by volume to about 1.75% by volume. A concentrate composition and also its use as an additive in damping solutions of an offset printing machine is likewise described.

Inventors:
MUELLER THOMAS (DE)
Application Number:
PCT/EP2011/005228
Publication Date:
April 26, 2012
Filing Date:
October 18, 2011
Export Citation:
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Assignee:
DC PLUS BETEILIGUNGS GMBH (DE)
MUELLER THOMAS (DE)
International Classes:
B41F7/24; B41N3/08
Domestic Patent References:
WO1998020075A11998-05-14
Foreign References:
US20090286701A12009-11-19
JPH06344533A1994-12-20
US5387279A1995-02-07
EP1688266A12006-08-09
Other References:
None
Attorney, Agent or Firm:
JACOBY, Georg (Widenmayerstr. 5, Munich, DE)
Download PDF:
Claims:
Claims . Process for modifying a damping solution of an offset printing machine, characterized in that a mixture of an alcohol selected from a monobutyl ether of mono-, di- or triethylene glycol, monobutyl ether of mono-, di- or tripropylene glycol, 2-methylpentane-2,4-diol (hexylene glycol) and

2-ethylhexanol (isooctyl alcohol), or a mixture thereof, and an acetic or propionic ester with any one of same alcohols or a mixture of such esters in a ratio of about 40-60:about 15-25 parts by volume is introduced in such an amount into the damping solution preparation unit of the offset printing machine that the total concentration of the mixture in the damping solution of the damping solution circuit is about 0.1% by volume to about 1.75% by volume.

2. Process according to Claim 1 , characterized in that the mixture is

introduced into a water feed line to the damping solution preparation unit.

3. Process according to Claim 1 or 2, characterized in that the mixture is

introduced into the water feed line in such an amount that the total concentration of the mixture in the damping solution of the damping solution circuit is about 0.2% or about 0.4% or about 0.6%, or about 0.8% by volume to about 1.5% by volume.

4. Process according to any one of Claims 1 to 3, characterized in that the mixture is in water-diluted form in a concentrate container and is introduced into the water feed line of the damping solution preparation unit via a metering pump or some other metering means.

5. Process according to any one of Claims 1 to 3, characterized in that the water and the mixture are in a volume ratio of about 0.2:1 to about 5:1.

6. Process according to any one of Claims 1 to 5, characterized in that the alcohol is diethylene glycol monobutyl ether (butyldiglycol). Process according to any one of Claims 6 to 10, characterized in that the acetic or propionic ester is 2-butoxyethyl acetate (butylglycol acetate).

Concentrate composition, characterized in that it comprises an aqueous mixture of an alcohol selected from a monobutyl ether of mono-, di- or triethylene glycol, a monobutyl ether of mono-, di- or tripropylene glycol, 2-methylpentane-2,4-diol (hexylene glycol) and 2-ethylhexanol (isooctyl alcohol), or a mixture thereof, and an acetic or propionic ester with any one of same alcohols or a mixture of such esters and water.

Concentrate composition according to Claim 8, characterized in that it comprises the aqueous mixture of an alcohol, an acetic or propionic ester and water in a volume ratio (alcohol plus ester):water of about 0.2:1 to about 5:1 , wherein the volume ratio of alcohol to ester in the mixture is about 40-60:15-25.

Concentrate composition according to Claim 8 or 9, characterized in that the alcohol, the acetic or propionic ester and the water are in a volume ratio of about 40-60: 15-25: 15-55.

Concentrate composition according to any one of Claims 8 to 10, characterized in that the volume ratio of alcohol, acetic or propionic ester and water is about 50:about 20:about 30.

Concentrate composition according to any one of Claims 8 to 11 , characterized in that the alcohol is diethylene glycol monobutyl ether (butyldiglycol).

Concentrate composition according to any one of Claims 8 to 12, characterized in that the acetic or propionic ester is 2-butoxyethyl acetate (butylglycol acetate).

14. Concentrate composition according to any one of Claims 8 to 13, characterized in that in addition to the aqueous mixture it further contains one or more customary damping solution additives comprising one or more from a viscosity enhancer, a corrosion inhibitor, a complex agent, a biocide, a surfactant/wetting agent, a stabilizer, a dye and a scent.

15. Use of a concentrate composition according to any one of Claims 8 to 14 as additive in a damping solution in a damping solution circuit of an offset printing machine.

16. Use according to Claim 15, characterized in that the concentrate

composition is added to the damping solution via a water feed line to the damping solution preparation unit.

17. Use according to Claim 15 or 16, characterized in that the concentrate

composition is introduced into the water feed line in such an amount that the total concentration of the nonaqueous concentrate constituents in the damping solution of the damping solution circuit is about 0.1% by volume to about 1.75% by volume.

18. Process for modifying a damping solution, characterized in that damping solution additives having two or more components are introduced via at least two separate metering means into a water feed line to a damping solution preparation unit of an offset printing machine.

Description:
Damping solution additive for offset printing machines Field of invention The invention relates to a process for modifying a damping solution of offset printing machines and also to a concentrate composition useful as an additive in the damping solution.

Background of invention

Offset printing is an indirect chemical planographic printing process which is widely used in book, newspaper, jobbing and packaging printing and which is based on the principle of hydrophilicity and hydrophobicity, more specifically usually the repellence between fat and water. In the last case, the printing forme is coated with an aqueous damping solution before contact with printing ink. The nonprinting part of the printing forme rendered hydrophilic is wetted by the aqueous damping solution to which no hydrophobic and/or oil-containing ink adheres. The printing parts of the printing plate or forme are lipophilic or hydrophobic, repel water and are not wetted by the damping agent, they attract oils and lipophilic solvents and therefore accept the printing ink containing substances of this type.

Offset printing is further an indirect process of printing. The printing forme does not print directly onto the printing stock, e.g. paper, but first deposits the printing ink on a rubber blanket. It is only this rubber blanket which transfers the ink to the paper, hence the elements to be printed are in a read-right position on the printing forme, unlike other printing processes. Ink transfer in offset printing only requires slight contact pressure.

Transporting the printing ink and the damping solution to the printing forme which in reel-fed offset printing is carried by a first cylinder is done by rolls forming part of the inking system and the damping unit of the printing machine. A second cylinder is covered with the rubber blanket. The third cylinder is a counterpressure cylinder which form part of a lower printing unit and may likewise be covered with a rubber blanket. In other words, in reel-fed offset printing, the first-impression and the back-up sides can be printed simultaneously in successive printing units. The paper web passes between the second and third cylinders. Folding assemblies are connected to the machines.

Up to about 75 000 sections per hour are printed in reel-fed offset printing. The paper web is unwound off a reel in the process. Reel change is done on the fly in comparatively large installations. The web of the new reel is glued to the end of the paper web on the running machine and so printing can be continued without interruption.

A printing stock, e.g. paper, that dusts will contaminate the rubber blanket.

Depending on the grade of printing stock, the rubber blanket has to be cleaned on the running machine after about 20 000-40 000 sections. In this operation, all rubber blankets are cleaned, at full or reduced printing speed, by means of an automatic washer which is fixedly installed on the printing machine.

During the operation of washing, the paper continues to run through the printing machine. This paper goes for broke (becomes waste, that is). The washing operations with regard to the rubber blankets thus give rise to unproductive dead time and broke, which generally amounts to between 4 and 10% of the entire paper used. Paper in turn represents the largest expense item in a printing works.

It is an object of the present invention to reduce printing machine dead time and broke.

Summary of invention

The invention provides a process for modifying a damping solution of an offset printing machine, characterized in that a mixture of an alcohol selected from a monobutyl ether of mono-, di- or triethylene glycol, monobutyl ether of mono-, di- or tripropylene glycol, 2-methylpentane-2,4-diol (hexylene glycol) and

2-ethylhexanol (isooctyl alcohol), or a mixture thereof, and an acetic or propionic ester with any one of same alcohols or a mixture of such esters in a ratio of about 40-60:about 15-25 parts by volume is introduced in such an amount into the damping solution preparation unit of the offset printing machine that the total concentration of the mixture in the damping solution of the damping solution circuit is about 0.1 % by volume to about 1.75% by volume.

The invention further provides a concentrate composition characterized in that it comprises an aqueous mixture of an alcohol selected from a monobutyl ether of mono-, di- or triethylene glycol, a monobutyl ether of mono-, di- or tripropylene glycol, 2-methylpentane-2,4-diol (hexylene glycol) and 2-ethylhexanol (isooctyl alcohol), or a mixture thereof, and an acetic or propionic ester with any one of same alcohols or a mixture of such esters and water.

The invention further provides for the use of the concentrate composition according to the invention as an additive in a damping solution in a damping solution circuit of an offset printing machine.

The invention finally provides a process for modifying a damping solution, characterized in that damping solution additives having two or more components are introduced via at least two separate metering means into a water feed line to a damping solution preparation unit of an offset printing machine.

Detailed description The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. One of the essential offices of the damping solution in a printing machine of the offset process is to wet the printing plate in order to ensure, at the time of ink application, that the printing ink should only adhere to those places on the printing plate which shall subsequently also produce the printed image. The damping solution is thus a consumable which is continuously consumed in printing.

The damping solution consists of water (generally tap water or partially

demineralized water) and additives. The mixture is prepared continuously in the damping solution preparation unit of the printing machine, from 2 or at most 3 components. When damping solution is prepared from 2 components, a mixture of additives, which is referred to as damping solution concentrate or additive, is mixed into water, while in the case of the preparation from 3 components alcohol, generally isopropanol, is added to the water as well as the damping solution additive.

Metering the damping solution additive into the water is done from a stock reservoir container via a metering means directly into the container of the damping solution preparation unit. The maximum concentration of damping solution additive in the damping solution is normally not more than 5% by volume.

The damping solution additives currently used in offset printing are aqueous mixtures of various constituents and contain essentially the following components: a) about 1 -20% by weight of buffer substances, for example

polycarboxylic acids and salts thereof, such as citric acid/citrate (e.g. from citric acid and inorganic bases such as aqueous sodium hydroxide solution). Dicarboxylic acids having 4 to 10 carbon atoms are particularly suitable;

b) about 5-70% by weight of one or more solvents/wetting agents, such as alcohols, glycol ethers, acetates, glycols;

c) about 0.5-5% by weight of one or more solubilizers, for example hydrophilic thickeners such as modified starch or cellulose, polyols, polyglycols or similar substances customary for this purpose; d) about 2-10% by weight of one or more biocides (preservatives): for example bronopol, isothiazolinone, benzyl alcohol hemiformal, n- methylolchloroacetamide

e) about 0.01-5% by weight of one or more surfactants/wetting agents, preferably in nonionic form, for example tertiary acetylene glycol, ethylene oxide, propylene oxide and ethylene oxide/propylene oxide surfactant, fatty alcohol ethoxylates, fatty acid ethoxylates and siloxane alkoxylates,

f) about 0.1-5% by weight of defoamers based on stabilized copolymer dispersions for example on the basis of a stabilized copolymer dispersion,

g) about 0.1-10% by weight of one ro more corrosion inhibitors for iron/steel/nickel: e.g. phosphoric acids, such as orthophosphoric acid or polyphosphoric acid and/or salts thereof, tolyltriazole derivatives, copper ions

h) about 0.1-5% by weight of one or more complexing agents, such as EDTA, triethanolamine, phosphonic acid

i) about 25-90% by weight of water, preferably fully

demineralized/deioinized (completely ion-free water (fully Dl water, PURW).

Offices of the damping solution additive are:

• establishing a stable ink-water emulsion

• reducing the surface tension of the damping solution to improve plate

wetting

• improving damping solution transfer

• stabilizing the circuit pH

• preventing corrosion

• preventing formation of algae and microbes

• influencing the ink drying

• preventing salt deposits on the machine rolls (through complexation of hardness ions such as calcium and magnesium ions)

• preventing ink build-up on rolls It has now been found that, surprisingly, the addition of the above-defined mixture of an alcohol and an acetic or propionic ester to the damping solution of an offset printing machine, as described above, leads to less rapid soiling of the rubber blankets. This makes it possible to reduce the number of washing operations, which reduces dead time and the formation of broke.

The alcohol used in the mixture, which is also the alcohol in the concentrate composition according to the invention, is selected from the following alcohols: ethylene glycol monobutyi ether (or butoxyethanol or butylglycol):

CH3-(CH 2 )3-0-(CH 2 )2-OH diethylene glycol monobutyi ether (or 2-(2-butoxyethoxy)ethanol or butyldiglycol): CH 3 -(CH 2 )3-0-(CH2)2-0-(CH2)2-OH triethylene glycol monobutyi ether (or 2-(2-butoxyethoxyethoxy)ethanol or butyltriglycol):

CH 3 -(CH2)3-0-(CH2)2-0-(CH 2 )2-0-(CH 2 )2-OH propylene glycol monobutyi ether (or butoxypopanol):

CH 3 -(CH 2 )3-0-(CH 2 )3-OH dipropene glycol monobutyi ether (or 2-(2-butoxypropoxy)propanol):

CH 3 -(CH 2 )3-0-(CH 2 ) 3 -0-(CH 2 ) 3 -OH tripropylene glycol monobutyi ether (or 2-(2-butoxypropoxpropoxy)propanol): CH 3 -(CH 2 )3-0-(CH 2 )3-0-(CH2) 3 -0-(CH 2 ) 3 -OH 2-methylpentane-2,4-diol (hexylene glycol): CH 3 -CHOH-CH2-C(CH 3 )OH-CH3

2-ethylhexanol (isooctyl alcohol): CH3-(CH2)3-CH(C 2 H5)-CH 2 OH Preference is given to diethylene glycol monobutyl ether (butyldiglycol).

The acetic or propionic ester of the mixture, which is also the acetic or propionic ester in the concentrate composition according to the invention, is selected from any desired acetic or propionic ester of the above alcohols, but independently thereof: butoxyethyl acetate (butylglycol acetate) or propionate:

CH 3 -(CH 2 )3-0-(CH2)2-OC(0)-(CH 2 )o or 1-CH3

2-(2-butoxyethoxy)ethyl acetate (butyldiglycol acetate) or propionate:

CH 3 -(CH 2 )3-O-(CH 2 )2-0-(CH2)2-OC(0)-(CH 2 )o or 1-CH3

2-(2-butoxyethoxyethoxy)ethyl acetate or propionate:

CH3-(CH 2 )3-0-(CH2) 2 -0-(CH 2 ) 2 -0-(CH2)2-OC(0)-(CH 2 )o or 1-CH3 butoxypropyl acetate or propionate:

CH 3 -(CH 2 )3-0-(CH 2 )3-OC(0)-(CH 2 )o or 1-CH3

2-(2-butoxypropoxy)propyl acetate or propionate:

CH 3 -(CH 2 )3-0-(CH2)3-O-(CH2)3-OC(0)-(CH 2 )o or 1-CH3

2-(2-butoxypropoxpropoxy)propyl acetate or propionate:

CH 3 -(CH 2 ) 3 -0-(CH 2 )3-0-(CH 2 )3-0-(CH 2 )3-OC(0)-(CH 2 )o or 1-CH3

2-methylpentan-2-ol-4-yl acetate or propionate:

CH 3 -(CH 2 )o or i-C(0)0-(CH3)CH-CH 2 -C(CH 3 )OH-CH 3

2-ethylhexyl acetate or propionate:

CH 3 -(CH 2 )3-CH(C 2 H 5 )-CH 2 OC(0)-(CH 2 )o or 1-CH3 butoxyethyl acetate (butylglycol acetate) is preferred. Both the alcohol component and the ester component of the mixture used according to the invention and of the concentrate composition aqueous mixture according to the invention are high-boiling liquids having a low vapour pressure under ambient conditions.

The water in the concentrate composition according to the invention is generally deionized or completely ion-free water (fully Dl water/PURW).

The total concentration in the damping solution of the damping solution circuit of the mixture used in the process according to the invention is about 0.1% by volume to about 1.75% by volume, preferably about 0.2%, about 0.4%, about 0.6% or about 0.8% by volume to about 1.5% by volume, in the damping solution of the damping solution circuit, while the volume ratio of alcohol, to acetic or propionic ester in the mixture is about 40-60:15-25.

The mixture used in the process according to the invention may be in a water- diluted form in a concentrate container. In this case, the volume ratio of water to mixture may be in the range from about 0.2:1 to about 5:1 , and more specifically about 0.3:1 or about 0.4:1 to about 4:1 or about 3:1 , while the volume ratio of alcohol to acetic or propionic ester in the mixture is still as before about

40-60:15-25.

The volume ratio of (alcohol plus acetic or propionic ester) to water in the concentrate composition according to the invention is about 0.2:1 to 5:1 and specifically about 0.3:1 or about 0.4:1 to about 4:1 or about 3:1 , while the volume ratio of alcohol to acetic or propionic ester is still as before about 40-60:15-25.

The volume ratio between alcohol, acetic or propionic ester and water may be for example about 40-60:15-25:15-55. It is preferably about 50:about 20:about 30.

Accordingly, a mixture of diethylene glycol monobutyl ether (butyldiglycol), butoxyethyl acetate (butylglycol acetate), Fully Dl water/PURW in a volume ratio of about 50:about 20:about 30 is very particularly preferred. Optionally, the concentrate composition according to the invention may further contain small quantities of customary damping solution additives, which include one or more from viscosity-enhancing agents (for example polyvinyl alcohol and its derivatives for example in an amount of about 0.1 to about 5% (v/v or w/v), corrosion inhibitors (for example about 0.1% to about 5% w/v), complexing agents (for example about 0.1% to about 5% w/v), biocides (for example up to about 1% w/v) surfactants/wetting agents (for example pyrrolidone and its derivatives in an amount of about 0.1% to about 5% by volume), stabilizers (for example up to about 1.5% w/v, dyes (up to about 0.2% w/v) and scents (up to about 0.2% w/v).

The concentrate composition according to the invention can be used as an additive in the damping solution in a damping solution circuit of an offset printing machine. It is preferably added to the damping solution via a water feed line to the damping solution preparation unit. In general, the total concentration in the damping solution of the damping solution circuit of alcohol plus acetic or propionic ester is about 0.1% by volume to about 1.75% by volume, preferably about 0.2, about 0.4 or about 0.6 or about 0.8% by volume to about 1.5% by volume. To obtain the recited concentrations in the damping solution, the composition according to the invention is generally not mixed with customary damping solution additives, since the alcohol and ester components would generally not form stable mixtures in the same at the requisite concentrations. Therefore, the addition to the damping solution preferably takes place separately from the other damping solution additization, viz. preferably via a suitable metering means, for example a metering pump, into the water feed line to the damping solution preparation unit. It was found that this circumvents any possible solubility problems.

Unconsumed damping solution modified with the concentrate composition according to the invention, having passed through the damping solution circuit, is generally returned into the damping solution preparation unit via a filtering means or other cleaning means. Using the concentrate composition according to the invention surprisingly allows appreciably greater intervals between necessary washes of the rubber blankets.

This has very advantageous consequences:

- reduced broke

shortened order-processing times

reduced wash and consumable requirements

less waste

reduced emissions - enhanced environmental protection

- minimizing possible broken webs due to washing

reduced primary energy requirements.

A further aspect of the invention provides a process for modifying a damping solution, characterized in that damping solution additives having two or more components are introduced via at least two separate metering means into a water feed line to a damping solution preparation unit of an offset printing machine.

This process is advantageous when there are solubility problems or problems with the compatibility of individual components in a single mixture.

The example which follows illustrates the invention.

Example The concentrate composition was tested on a HEIDELBERG Harris M 600 offset printing machine, from 2001 , with 4 double printing units and a varnishing unit for 16 A4 pages using the following materials: damping solution additive: Wassertop HS 2.48 Spezial

- rubber blankets: Vulkan Alto Plus

printing plates: Kodak Polychrome XD plate thickness 0.3 mm

printing rolls: WESTLAND

printing inks: HUBER Revolution range paper variety: M-real Galerie Fine

water: tap water having a conductivity of 304 uS/cm and a German water hardness of 9.8° - concentrate composition consisting of diethylene glycol monobutyl ether (butyldiglycol), butoxyethyl acetate (butylglycol acetate), Fully Dl

water/PURW water in a volume ratio of 50:20:30.

Machine speed was 35 000 cylinder revolutions per minute.

To test the concentrate composition, an additional metering pump was installed into the water feed line to the damping solution preparation unit (Technotrans), the metering range of which was 0% to 5%. The damping solution preparation unit was filled with the concentrate composition (1 % by volume added), Wassertop HS 2.48 Spezial damping solution additive (3% by volume added) and 96% by volume of tap water. Metering was monitored via consumption data (water-meter and weighing scales). Conductivity and pH was measured.

Test result:

Adding 1 % by volume of concentrate composition gave a good printing result. Washing times and ink build-up on the rubber blanket decreased substantially. The ink feed was very stable and the water window was wide enough. Ink build-up on the dampening rolls is very low. The water feed can be reduced to minimal.

The print run was 8 million copies. 400 000 kg of paper were printed in

10 production days.

The percentage of broke was reduced by 2% from 4.5% to 2.5%.

The paper saved amounted to about 8,000 kg. The amount of concentrate composition consumed amounted to about

15 I - 20 I per production day. The entire content of all documents cited herein, such as patents, patent

applications, journal essays and sales brochures, is herein incorporated by reference.

It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.