DE2227485A1 - PRINT CYLINDERS FOR OFFSET PRINTING MACHINES - Google Patents

Description

DR. BERG DIPL.-ING. STAPF

PATENTANWÄLTE 8 MUNICH SO. MAUERKIRCHERSTR.

. Dr. Berg Dipl.-Ing. Stapf, 8 Munich 80, MauerkircherstraBe 45

Your sign Your letter Our mark

Attorney file 22 4-72 . Be / A

date

June 6, 1972

Kabushiko Kaisha Ricoh Tokyo (Japan)

"Printing cylinder for offset printing machines ¹¹

It is well known that offset printing is a printing process is, in which a color image (moistened), (usually from a moistened! planographic printing surface), first on an impression cylinder (usually a blanket cylinder) and then on the one to be printed

EPA 1077-1079 _209881/0439

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(0811) 48 82 72 <98 82 72) 48 70 43 <98 70 4j>& U ig (O 3B10] / Ifekftaijntf BERGSTAPFPATENT Mönchen TELEX 05 24 560 BERG d Bank: Bayerische Vereinsbank Mönchen 453100 Postscheck: Munich 653 43

Paper transfers, with offset printing being greasy or oily Printing ink is used which contains pigment, resin, drying oil and solvent.

For a better understanding of the invention, reference is made to the accompanying drawing, wherein Fig. 1 a Shows cross-section of the main parts of the offset printing machine as far as they relate to the invention. In Fig. 1, a Color image from a moistened planographic printing surface of a Forme cylinder 1 on a surface of a transfer cylinder, i.e. a cylinder 2 covered with rubber, and then transferred to the paper 3, the paper between two cylinder rollers, (the transfer cylinder 2 and the Impression cylinder 4), is guided by a paper transport device (not shown).

Awake to the finished printing process as a preparation for the next printing of the "transfer cylinder 2 with a Cleaning liquid 5 are washed, these from the cleaning device 6 by means of cleaning rollers 7 and 8 is fed. Such a cleaning liquid can be kerosene, toluene or xylene with a content of trichlorethylene or cyclohexane.

If the transfer cylinder is to be cleaned by placing paper between the transfer cylinder and the Can run through the printing cylinder without the cleaning device

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to use, 10 to 20 sheets of paper are required, to remove the ink from the transfer cylinder.

It is an object of the present invention to provide a to provide improved transfer cylinder available in which the printing ink on the transfer cylinder easily can be removed by placing 3 or 4 sheets of paper between the transfer cylinder and the impression cylinder can run through, whereby the cleaning device is dispensable in an offset printing machine.

The present invention relates to an improved transfer cylinder (Blanket cylinder) of an offset printing machine.

Using the improved transfer cylinder of the present invention in place of a conventional transfer cylinder in an offset press, can on. a cleaning device for the transfer cylinder is dispensed with because the printing ink on the transfer cylinder is easily made by passing 3 or 4 sheets Paper between the transfer cylinder and the impression cylinder can be removed.

The improved transfer cylinder can be formed by forming a üchicht or a film of high polymers with lower critical interfacial tension can be established on their surface ..

2ü9 881/0439

Such high polymers that have a low critical interfacial tension have and the values of the critical interfacial tension are given in the following table:

Critical interfacial tension (Dyne / cmTO

Polydimethylsiloxane 20

Polypropylene 23

Fluorine-containing high polymer,
for example poly- (1,1-dihydropentadecafluorooctyl methacrylate) 11

Polyhexafluoropropylene 16

letrafluoroethylene hexafluoropropylene copolymer 17th

Polytetrafluoroethylene 18

Polytrifluoroethylene 22

Polyvinylidene fluoride 25

Trifluorochloroethylene-vinylidene fluoride copolymer 25th

Hexafluoropropylene vinylidene fluoride copolymer 25th

With reference to the accompanying drawing, Pig.2 a method of measuring critical interfacial tension (fc) using a polypropylene film as an example will.

Water, glycerin and triethanolamine are on a surface a polypropylene plate and the angle

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O ₁ , Q ₂ and Q ₅ such as InJ ¹ Ig. 2 (a), I ¹ Ig ₀ 2 (b) and Pig »2 (c) are measured and the values cos 0-, cos Qp and

cos 0, obtained.

The angles -O ₁ , öp and Θ, and the cos values θ- ,, Q ₂ ^ηΐΩ - & ö * are:

= 82 ° COS Q = 0.14 ^Θ 2 = 75 ° cos θ = 0.26 S. = 59 ° cos Q = 0.51

The surface or _e G-rence surface tension of water, glycerol and Iriäthanolamin are:

Water 72 dyne / cm

Glycerin 65 ^M triethanolamine 5O "

From the values mentioned above, as in Prg. 2 (d) shown the points A, B and 0 with the values of the interfacial tension as abscissa compared to the values of cos θ plotted as ordinate »

From the point of intersection or the intersection line D of the extension the points A, B and G and the line at which cos θ = 1 is drawn perpendicular to the abscissa. on this way the critical interfacial tension of

Obtained polypropylene

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The values of the critical interfacial tension of the other high polymers can be determined in the same way as indicated above, be measured.

However, in the case of a high polymer formed in an organic Solvent, such as polydimethylsiloxane, is soluble, the critical interfacial tension can be obtained by that one uses a layer of the high polymer obtained by applying a solution of the high polymer to a surface of a solid body and then formed by drying it.

The layer or film of the high polymer given above -With the lower critical interfacial tension, the surface of the transfer cylinder can in the following Way to be formed:

(1) by applying a solution of the high polymer in an organic solvent to the surface of the transfer cylinder and then by drying, or

(2) by wrapping a film of the insoluble high polymer around the transfer cylinder.

It was found that the applied to the cylinder Printing ink bearing a layer or film of the above-mentioned high polymer on its surface the paper to be printed in a higher than 80 / day

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2227A85

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Amount, based on the printing ink, can be transferred ".

The printing ink that is present on the transfer cylinder Invention is printed on, can therefore be easily removed by just placing several sheets of paper between the transfer cylinder and the printing cylinder can pass through. It can therefore rely on a washing process of the transfer cylinder with cleaning liquid when the printing process has ended, be waived.

The (absolute) migration speed of the printing ink from the forme cylinder to the transfer cylinder is lower compared to that using the conventional rubber-covered cylinder. However, the_walking speed is the printing ink from the transfer cylinder on the paper to be printed is higher compared to the conventional one Gummy cloth cylinder, so that a printed material with higher density can be achieved.

The present invention is illustrated by the following examples.

The following offset printing machine and offset printing ink were used in the examples.

Offset printing machine from KK Hicoh under the trademark "RICOH OPFdEl ¹ 1000".

-8th-

2 09 88 1/043 9

An offset press was used with the cleaning device removed.

The offset printing ink was made up of the following ingredients manufactured:

Parts by weight

Carbon black 3.8

Alkyd resin 5.0

Tall oil 5.6

Xylene 5.4

Cobalt naphthenate 0.2

Polybutene (Nippon Petrochemicals Oo.,

Ltd., trademark "LV-10") 5.4

Esters of alginic acid and propylene glycol

(2 "/ olge aqueous solution) 50.0

Polyvinyl methyl ether-maleic anhydride copolymer 0.5

liquid paraffin. 1.0

Monoethanolamine 0.4

Water 75.0

example 1

An organic solution was made from the following ingredients:

Parts by weight

Polydimethylsiloxane (Shinetsu Silicone

Go., Ltd., trademark "KE42TS") 10

n-heptane '10

—Q_

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The organic solution produced in this way was applied to a transfer cylinder (a nitrile-butadiene-rubber-padded cylinder) and then ^{dried at a temperature of 50 °} C. and a relative humidity of 60 % for 48 hours. A layer of polydiraethylsiloxane with Tc of 20 dyne / cm was formed on the surface of the transfer cylinder. Performing the printing process using the transfer cylinder prepared above provided a higher density printed material. After the end of the printing process and after the planographic printing surface (or the original image) had been removed, papers were passed through between the transfer cylinder and the impression cylinder. The transfer cylinder could be cleaned by passing paper sheets through it.

Example 2

The same procedure as in Example 1 was repeated except that polydimethylsiloxane manufactured by Shinetsu Silicone Co., Ltd., trademark "KE45S-RTV" in place of "KE42TS" in Example 1 was used.

When using "KE4-5S-RTV" a layer of polydimethylsiloxane with Tc of 20 dyne / cm was formed on the surface of the printing cylinder.

The same result as in Example 1 was obtained.

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Example 3

A film of tetrafluoroethylene-hexafluoropropylene mixed polymer (E.I. du Pont de Nemours and Co., Inc., trademark "TEiXON FEP") with a thickness of 0.5 mm and ^ of 17 dyne / cm was placed around the transfer cylinder instead that a layer of polydimethylsiloxane was formed on the surface of the transfer cylinder. Using of such a transfer cylinder, the same result as in Example 1 was obtained. The transfer cylinder could can be cleaned in the same way by passing 3 sheets of paper through after the printing process has ended.

Example 4

A film of polypropylene with a thickness of 0.2 mm and Tc of 23 dyne / cm instead of "TEFLON FEP" in Example 3 was applied around the transfer cylinder.

The transfer cylinder could by passing through Sheets of paper should be cleaned after printing is finished.

Example 5

A film of polyvinylidene fluoride having a thickness of 0.3 mm and Tc of 25 dyne / cm was applied around the transfer cylinder. Using such a transfer cylinder, the same result as in Example 4 was obtained.

According to the invention, a metal cylinder, such as aluminum

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minium, copper, brass, iron or stainless steel 'as Cylinder as a transfer cylinder instead of the blanket cylinder, or it can be a synthetic resin cylinder Resin such as phenolic resin, epoxy resin, acrylic resin, melamine resin, polyester resin or acrylonitrile-butadiene-btyrene is used will.

The metal or resin cylinders can be used in the manner by covering the surface of the cylinder with a film of the above-mentioned high polymers.

-Patent claims-

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Claims (5)

- 12 patent claims: 1. transfer cylinder of an offset printing machine, characterized in that it has a Layer or film made of a high polymer having a low critical interfacial tension of less than 25 dyne / cm on a surface of the transfer cylinder. 2. Transfer cylinder of an offset printing machine according to Claim 1, characterized in that the high polymer is a fluorine-containing high polymer, 3. Transfer cylinder of an offset printing machine according to claim 1, characterized in that that the fluorine-containing high polymer poly (I.1-dihydropentadecafluorooctyl methacrylate), Poly-hexafluoropropylene, l'etrafluoroethylene-hexaflouropropylene copolymer, Polytetrafluoroethylene, polytrifluoroethylene, polyvinylidene fluoride , Trifluoroethylene-vinylidene-fluoride mixed polymer and / or hexafluoropropylene vinylidene fluoride copolymer. 4-. Transfer cylinder of an offset printing machine according to claim 1, characterized in that that the high polymer is polydimethylsiloxane. 2U9 88 1/0439 2227A85 5. transfer cylinder of an offset printing machine according to claim 1, characterized in that that the high polymer is polypropylene. 2U9881 / 0439 AH Blank page