DE2248606A1 - WETTING LIQUID COMPOSITION FOR AN OFFSET PRINTING PLATE - Google Patents

Description

PATHNTANWÄL'fe

H. LElNWIiBER dipping. H. ZIMMERMANN

DIPL.-ING. A. Gf. ν. WENGERSKY - _:

S MUNICH 2, ITASENTAL 7, 2nd exercise.

7 7 U 8 6 O 6 ΤΘΐ.-Adr. iefnpat MUndien

Telephone (0811) 2683989

Postschedc account: Munich 22045

^the October 4, 1972

Our sign

Z / P / Sm - POS 28

MITSUBISHI PAPER MILLS, LTD., Chiyoda-ku, Tokyo / Japan Wetting liquid composition for an offset printing plate

The present invention relates to a wetting liquid Composition to improve the printability of a basic offset plate or pressure plate. In particular, the invention relates to a wetting liquid composition which for wetting a presensitized printing plate, an offset printing plate operating with a silver salt diffusion transfer system (For example, as described in Japanese Patent Publication 14 330/67 and Japanese Patent Application 72 039/67 according to the USA patent application Serial Ιο. 71 is described) or a silver salt offset printing plate, such as the photolithographic plate containing the developer described in U.S. Patent 3,146,104.

The effect of a wetting or “dampening liquid” in offset printing is known to be on the non-printing areas (ie the ink-wetting hydrophilic areas)

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give a printing plate a uniform ink-repellent effect imparting, whereby a smooth printing can be achieved and a clear print copy can be obtained.

However, it has often been found in printing processes that the conventional wetting fluids even using a suitable method of consultation does not allow hard copies to be made deliver with consistent properties.

Further, in the case of the conventional wetting liquid-j in which the most diverse chemical substances are contained together, difficulties with regard to the Storage stability and problems in obtaining clear hard copies have occurred. In addition, by the not provided If ink adheres to non-printing areas of the copy, the base color can easily be stained. This phenomenon probably depends, among other things, on the type of printing ink, the ambient conditions (temperature or humidity of the working area) and the number of wetting processes.

When printing for a long time On the other hand, the oil components present in the printing ink cause emulsification of the wetting liquid causes. This emulsification prevents sticking the printing ink on the printing areas, with the result that these areas are broken or non-printing areas get stained with paint. The wetting effect and the emulsification phenomenon are closely related to one another. The wetting liquids with high wetting power generally tend to cause emulsification; those

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Wetting liquids which do not cause emulsification show essentially no wetting effect. It therefore exists a need for wetting liquids with good resistance, so that a satisfactory balance between the two named phenomena is taken care of.

It was found that the wetting liquids used in the conventional manner, which have an i ! or more hydrophilic substances such as carboxymethyl cellulose! Gum arabic, sodium alginate, glycol compounds and metal salts of nitric acid, phosphoric acid, etc., are 'not' suitable for printing processes carried out over a longer period of time. The properties of many of these wetting fluids! are also subject to very strong fluctuations, which depend on the The type of plates, the type of printing inks and the variation in the printing conditions depend. Such wetting liquids are sine not suitable for practical purposes. For example, if printing is carried out using an offset printing plate, at which the silver salt diffusion transfer system is applied and which by providing a polyester film with a hydrophilic base layer and subsequent application of a surface layer to it, the seeds for physical development in the form of fine particles of heavy metals or their sulfides and up to 30 percent by weight (based on these germs) a compound with a high molecular weight (cf. the US patent registration Serial No. 71 632), emulsification occurs particularly easily. When this emulsification is suppressed, the equilibrium in terms of wetting effect is lost, resulting in contamination of the j Hard copies leads.

In an attempt to eliminate the aforementioned disadvantages, various stabilizers and dispersants were used .

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ι and Aktivaloren added. Has been made by such an addition j but rather the aggregation-precipitation-effect and the buffer- ' effect influenced.

; Extensive studies of the inventors in ^view; the above-described liachteile and undesirable phenomena in offset printing have shown that a wetting ^; liquid composition which contains four components, ie, A) at least one type of transparent, water-insoluble '■

fine particles with a grain size of 0.1 micron or less, preferably at least one sol of an oxide or hydroxide; one of the III. or IV. group of the course period system hearing metal, such as colloidal silicon dioxide or aluminum oxide,

13) at least one organic or inorganic alkali salt, preferably anhydrous salt, such as the sulfates, halides or ilitrates of sodium and potassium, in some cases containing water of crystallization Salts, ■ I

C) at least one low molecular weight polyhydric alcohol _: and / or l.iindectens a polyalkylene oxide with a molecular weight of at most 1000, such as polyethylene glycol, propylene glycol, pentaerythritol or glycerol, as well as

D) at least one of those conventionally used to speed up printability and maintain an appropriate pjj value used weak organic acids such as citric acid, succinic acid, tartaric acid, adipic acid, or ascorbic acid Propionic acid,

has a remarkably high stability and is capable of doing so, the printability of offset printing plates is very strong to improve. Under "polyalkylene oxides having a molecular weight from a maximum of 1000 "are to be understood here as the commercially available polyalkylene oxides.

t; j

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. The aforementioned component A) preferably has a particle size rüLu of at most. O, 1 micron, preferably 0.001 to 0 o ^r j microns. The reason for this is that if this component takes the form of a v / äs acidic dispersion, it must be transparent, it must not lose the water retention effect and it must be compatible with the other components. In this case, the ionic and covalent bonds with the alkali salt appear to create a stable dispersion.

It is most useful to set the pn-V / ert to et ¹ Ja 4.0 to b ', b after wetting. This p ^ setting is made with the aid of the aforementioned weak acids or their salts, such as sodium acetate, borax or sodium citrate.

A ptT fourth caused outside of the aforementioned range thus a significant reduction in printability and instability of the liquid. The said liquid naturally takes the form of an aqueous dispersion.

In this case, it is necessary to limit the proportion of cbr components; the finely divided component A) is preferably present in a proportion of about 0.1 to M> _t, in particular about 0.5 $ (as a solid). The proportion of the alkali salt component B) is preferably 3 to G times, in particular 4 to 6 times, the proportion of the fine T-compounds mentioned. The polyol is preferably b to 10 i "present in a proportion of about even though this amount depends on the adjustment of the viscosity and the resistance. Component D) (black organic acid) can be used in an amount required to set the o ^ value; their proportion is preferably 0.1 to 10 percent by weight of the wetting composition. _: ■

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The Müssigkol !. is diluted to about iu- to 20-fold. The percentage of thinning depends on the plates, the type of printing ink and the given pressure (type of printing machine, external interference limitation) and cannot be set within a defined range ,, 'la dilution degree of the less than fold 10 leads l'.' However, allo of orfindungsgemclßen wetting composition easily iinulgierun _a;. occur _J scu'Gcheinung, while a dilution level of Lieh j as dom 20-fold difficulty in bite-cutting operation läiöt.

With regard to the Unteracheidimgcvormögon and the appearance the wetting liquid composition can also contain dyes such as cobalt chloride, iiangan chloride, phthalocyanine pigment, Malachite green or ultramarine, in a small amount [can be added.

Furthermore, if necessary, hydrophilic substances such as carboxymethyl cellulose, gum arabic, sodium alginate, vinyl pyrrolidone, vinyl iiaidazole, methyl vinyl ether or maleic anhydride, which substances represent tried and tested conventional wetting components, organic solvents which are miscible with water, such as methanol, dimethylformamide or dioxane, and those in der ion-containing compound described in Japanese Patent Publication 1o 910/61 and United States Patent 3 490 90b ^!

j be added. ;

ι ^:

The invention is now intended to be based on the following examples explained.

^; example 1

i'lc is a liquid made from two parts by weight of water, b parts by weight of succinic acid, ü, 4 parts by weight of borax, 2b

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Parts by weight of anhydrous sodium sulfate, 2.2 parts by weight Cobalt chloride-he: .ahydrate, 100 parts by weight ethylene glycol and 2o parts by weight of colloidal silicon dioxide (2u percent liquid) produced. The p-fourth of the liquid is

Ij

·}, «-. The liquid is diluted with 1j times the amount of water ", thereby making a wetting liquid composition tii auxiliary liquid).

Wan also makes a printing plate by cliing a base with a thickness on a polyester Lasis film of Ίου microns and the foil in one by going together The paliadium sulfide sol prepared from liquids I to III described below is immersed:

Liquid 1:

ο g PdCl, AO ml HCl, Ή; · ϋϋ ml water;

Liquid II:

o, b g im.pS, 30 ml Polyäthjlenglykoi, "iü nil alkyl ether (Ίο percent), 1uo0 al water;

Liquid III:

1ou inl iiethylvinyl [ither / i-ialeiiicäureaii] ihydrid-uo] ^ olymer (1, 2i) percent).

On the offset printing plate obtained in this way, an image is transferred from an original original using the silver-as-diffusion transfer process. Subsequently, the Oifset pressure plate is wetted with the aforementioned wettable liquid, for example. water stirrer made. Then the plate is used suiü Druck in a commercially available OfiGet printing machine. The conditions for printing are normal temperature (23 ⁰ C) and VY> »relative humidity.

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Comparative example 1

A conventional wetting liquid containing 10 g of NILHoP
V) g Νϊ (Ν0 ₇ ) ο · ο HoO, 4 g carboxymethyl cellulose, 100 g glycerine
! and contains 1000 ml of mixing water, add water to the 10-
; times thinned.

I I

Comparative Example 2 ;

An analogous wetting liquid is used as in Bei- |

game 1 used, but in which the sodium sulfate and the ^l ! colloidal silicon dioxide can be omitted or replaced by tertiary sodium phosphate. i

j The table below shows the properties that j

j with the wetting liquids described above er j be targeted.

Tabel

Example 1 comparative comparative | example 1 example 2>

j resistance h- O -

, Emulsification state + X -

Spotting of the - \ - X
ι base color

j ■ π-! very good
O: good
X: relatively bad i

-: bad

The above evaluations were made with the naked eye. It

mean: .

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Persistence: According to the degree of clarity of the liquid

Leave to stand for 7 days at constant temperature and humidity.

Emulsification degree of clarity of the liquid and additive at . the wetting roller stopped after about 1

Hour from the start of printing.

Staining Degree of staining or soiling of the base color: _{at 50>? m} ^ _m ^ r _{jQQe and}

Hard copy.

The wetting condition is always the same in the above experiments.

The wetting effect achievable according to the invention is not much affected by differences in type of ink and process conditions; with appropriate Experiments essentially give the results shown in the table above.

Example 2 .

Basically the same effects as in Example 1 are achieved if, in this example, aluminum oxide sol is used instead of colloidal silicon dioxide and a mixture of 60 g of polyethylene glycol and 20 g of ethylene glycol were used instead of ethylene glycol.

Example 3

5 g of 4-phenyl catechol and 50 g of dibutyl phthalate are dispersed in 300 g of a 10 percent gelatin solution

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greed. The dispersion obtained is in turn with the help of a Colloid mill in a dispersion medium of 25 ml of 8 percent Saponin solution and 180 ml v / water dispersed. One obtains a developer dispersion.

An aqueous dispersion is then prepared with the following composition:

aforementioned developer dispersion 120 g

aqueous gelatin solution (10 percent) 400 g aqueous saponin solution (15 percent) 50 g

aqueous formaldehyde solution (formalin) (2 percent) 5 g

Water 425 g

The aqueous dispersion is applied to a paper carrier on which polyethylene is laminated (applied proportion: about 7 g / m). When the layer obtained is fixed, a photosensitive liquid is also applied to it the following components applied in a proportion of 15 g / m:

AgCl emulsion (silver concentration 3.2 mol percent) 600 g

v / a syry saponin solution (15 percent) 40 g

aqueous forraaldehyde solution (2 percent) 7g

V / ater 830 g

The cloudy photosensitive coating liquid obtained by mixing the following liquids I and II is also applied to the last-mentioned layer in a proportion of about 7 g / m 2. The deterioration of the liquid v / urde made by chemical means during about 40 minutes above 4O ⁰ C.

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Composition of liquid I:

AegCl emulsion (silver concentration 3.2 mole percent) 360 g

V / ater - '200 g

IaOH (0.25N) 24g

aqueous formaldehyde solution (2 percent) 5 g

Composition of the liquid II:

H ₂ SO ₄ (2 n) ■ 3.5 g

aqueous saponin solution (15 percent) 10 g

aqueous formaldehyde solution (2 percent) 2 g

Water 955 g

The offset printing plate obtained in the manner described above is exposed through a line original. The exposed plate is about 20 seconds with a 4 percent aqueous sodium carbonate solution and then Treated for 1 minute with 2 percent acetic acid as a breaker solution. Eventually the plate is through a 1 percent aqueous phosphoric acid solution out. A printing plate is obtained.

This plate is used in the manner described in Example 1 using the same wetting liquid Offset printing carried out; essentially the same results as in Example 1 are obtained.

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Claims (4)

P a i G η 1, a n s ρ r υ c Ii ο: Lasting liquid compound for an offset printing plate t do, abstain h) at least one type of transparent, water-insoluble.! a particle with a grain size of 0.1 micron or less, L>) at least one jilkalisalio, G) at least; a low molecular weight polyhydric alcohol and / or at least one; a polyalkylene oxide with a molecular weight of liüchsteiiü 10UÜ, as well as
D) at least one weak organic acid. 2. Composition according to claim 1, characterized in that component A) is at least one sol of an oxide or hydroxide of one of III. or IV. Group of metals belonging to the periodic table, such as colloidal silicon dioxide or aluminum oxide, component B) at least one sulfate, halide and / or kitrate of sodium and potassium, component G) poly; ith; _; . Ionic glycol, propylene glycol, pentaerythritol, glycerine, diethylene glycol and / or hexylene glycol and component D) are citric acid, succinic acid, tartaric acid, adipic acid, ascorbic acid and / or propionic acid. 3. Composition according to claim 1, characterized in that it has a pu value of et v / a 4.0 to 3.6. 4. Composition according to claim 1 to 3, characterized in that the proportion of component A) about 0.1 to 1 f °, that of component B) about 3 to 8 times that of component A), that of component C. ) about b to 10 $> and that of component D) about 0.1 to 10 percent by weight of the composition. 309816/1052 BATH