HRP920276A2 - Offset printing ink - Google Patents

Description

With the development of printing over the past thirty years, offset printing has become the predominant technology in the entire printing industry. The production of offset printing inks amounts to 40% of the total European and world production of printing inks. There are several reasons for this, but the basic one is the quality, application and development in the production of printing offset machines. In addition, this type of printing pollutes the environment very little or negligibly, and special devices for environmental protection are not required, as is, for example, required with gravure printing technology.

In printing machines where sheets of paper are printed, the colors dry by penetration, oxidation and decomposition of the binder. Due to modern machines that work at 12 and more thousand since, (araka) per hour and practically the print must be so dry in such a short time that the colors no longer rub off during further processing, it was necessary to make colors that will be suitable for such requirements . Due to the preservation of knowledge in that area, it was not possible to find such binders, nor information for the production of paints, so a group of experts had to work intensively for three years. such colors, because otherwise the production of offset colors would cease.

Three types of new offset inks have been produced that meet the previously described requirements:

1) quick-drying colors (type 22) offset

2) fast-drying inks for packaging printing, for food products (type 26) offset

3) fresh offset colors (type 28)

All these colors are made in 11 basic shades from which another 73 shades can be made according to the given recipes in the printing shops themselves.

Within the 11 basic shades, there are shades for "EUROPA SCALE" and "DIN SCALE", which greatly facilitates work in printing houses, as well as in color production itself.

Shades for all three types of colors will be marked with the same three-digit codes, and the addition in front of the shade code 22, 26 or 38 indicates the purpose of that offset color.

Markings and characteristics for 11 basic offset colors

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When mixing these 11 basic colors, attention should be paid to the characteristic so that it is not used incorrectly. Namely, the characteristic of the mixed color has the same characteristic as the basic color with the worst characteristics.

Raw materials and semi-finished products that enter the offset color system

1. Binders

2. Pigments

3. Alkyd

- linen alkyd-

It serves to increase the adhesion of colors on the substrate and to increase the gloss of the printed color.

- viscosity 116 P

- acid number 5.2

- tolerance to AF oils (non-aromatic) 737% (unlimited)

4. Offset gel

13 Al-linoleate

77 Linseed oil

10 Mineral oil

5. Co sicative

7 Cobalt oxide hydrate

59 Organic carbonic acid

34 Mineral oil

It serves to accelerate the surface drying of colors.

6. Sprimol paste

14 Benton

8 Mn borate (manganese)

5 Linseed oil alkyd

23 Linseed oil

30 Mineral oil

It serves to speed up the drying of the paint.

7. Retarder

20 Zuinol

80 Diethylene glycol

It serves to slow down the surface oxidation of colors in the mass.

Technological process of making offset colors (continuous) for flat printing

(scheme no. 1)

Binder I and Binder II are batched into the device for mixing and pre-dispersing the paint according to the work order via the flow meter, and with intensive mixing (1000-1200 rpm) the solid components are dosed via an automatic scale. The mass is pre-dispersed for 30 minutes, i.e. until the temperature of 55-60oC is reached. The heated and pre-dispersed mixture is fed by a toothed mono-pump into the pearl mill filled with steel and glass balls (depending on the shade), and the color flow through the mill is determined by the type of mill, type of pigment, choice of binder, and color temperature.

In the pearl mill, the color dispersion process is carried out, so at the exit from the pearl mill, the fineness of the particles is controlled, and the flow is adjusted for further continuous work. The color tested in this way is transported through the filter and dosed to the trowel. The role of the polisher is to increase the shine of the paint (orientation of the molecules) and remove possible impurities and thereby ensure a quality product, and cool the paint to 25-30oC. The pressure between the rollers is 40-60 bar. The quality of the paint is tested according to the internal regulations provided for this type of paint.

Additives are dosed from tanks 10 and 11 to the color tested in this way, they are homogenized with the color and the final quality control is performed.

If the quality is not satisfactory, either the process of dispersing on the poison roller is repeated or correction is made by adding binders or additives from tank 10 or 11, all in agreement with the technologist.

The tested color is filled with a filler into the available packaging.

Technological process of making offset colors (discontinuous) for flat printing

(scheme 2)

The binder is dosed into the moving vessel (boiler) via a flow meter and the solid components are dosed via automatic scales according to the work order. The moving vessel is placed under a high-speed mixer (1000-1200 rpm) where the work of pre-dispersing the paint is carried out until a temperature of 55-60oC is reached. The heated and pre-dispersed paint is dosed onto the roller at 100-150 bar pressure between the rollers (depending on the type of roller).

The fineness of dispersing is tested after the trowel, so if it is within the permissible limits, the necessary additives are dosed manually (it is about quantities of up to 10 kg per batch). Homogenization of additives with color is done under a high-speed mixer.

Instead of a trowel for dispersing paint, a pearl mill can be used (which is not shown in scheme no. 1), depending on the type of offset paint. Quality control is performed according to the internal regulations provided for this group of colors, and any repairs are made in agreement with the technologist.

The tested color is filled with a filler into the available packaging.

Laboratory control for the production of offset inks

1) Pigments

It is necessary to examine:

- pigment shade

- coloring intensity

- oil absorption

- bulk weight

- dispersing quality

2) For all pigments, the shade is tested according to a standard sample. The shade of all pigments must be identical to the standard, considering the exact recipes of mixing 73 shades and considering the shades of Europe and DIN scale.

3) The shade test method consists of the following:

The standard pigment and the pigment to be tested are uniformly dispersed on the Engelsman apparatus in linseed oil. It is necessary to disperse 10 g of a mixture of pigment and linseed oil in a ratio of 30 pigment to 70 oil. The mixture (paint) dispersed in this way is visually determined whether the shade is correct or not, it is printed on paper on the machine for test prints.

If the shade does not match completely (what the human eye can register), the pigment should not be used to make basic colors.

4) For all pigments, the intensity is tested in comparison with a standard pigment sample by mixing it with white paint (DIN norm no. 53204).

it is very important that the intensity does not deviate by more than ± 5%, because otherwise it would be impossible to tint the 73 shades according to the given recipes.

5) Oil absorption of pigments is tested according to DIN standard no. 53199, and should correspond to the oil absorption of the standard sample (or catalog data).

6) The bulk weight of the pigment is tested according to DIN norm no. 53194 and should correspond to the bulk weight of the standard sample, i.e. catalog data.

If the oil absorption or the bulk weight deviated significantly, this would affect the paint in such a way that the viscosity and flow of the paint would change significantly, which certainly affects the quality of the paint.

7) The quality of dispersing pigments is controlled on the Englesman apparatus by scrubbing the mixture of standard pigment and linseed oil, and the pigment being tested and linseed oil, with glass plates at 40 revolutions. The fineness of the pigment particle is determined with a grindometer - DIN norm no. 53203.

The particles after scrubbing must not be larger than 15 μ.

8) Alkyd

It is necessary to examine:

- viscosity

- acid number

- compatibility with AF oil

Viscosity should be 115-120 P, DIN norm 53015.

The acid number should be around 5.2 DIN norm 53402 or 53183.

Tolerance with AF oil about 740% (unlimited).

9) Offset gel

The stability of the gel structure is tested.

The prepared offset gel is left at room temperature for 24 hours. If the gel structure has not changed after 24 hours, it means that the offset gel is stable, and that it can be used either in color or as an addition to color during printing.

10) Co-sicative

The action of the shearing agent is tested.

1% Co detergent is added to bleached linseed oil. The oil should dry on the glass in 3 hours, unlike the oil itself, which dries on the glass in a 0.2 mm layer for 48 hours.

11) Sprimol paste (Sikativ)

The effect on the drying of paint is tested.

The addition of 2% Sprimol paste should dry a thinner spread of linseed oil in 24 hours. Without this slight drying effect, the oil dries in a thin layer on the glass for 48 hours.

12) Retarder

The action against the surface drying of the paint in the mass is tested - the property against "skinning" of the paint.

It is tested by applying a retarder in a very thin layer to the surface of the paint, which is in a small glass container with a diameter of 8-10 cm. Surface "skinning" must not appear on the paint for 24 hours.

13) Wax paste

It is examined:

- appearance

- size of particles - crystals of polyethylene wax

It should be visually determined that the paste has a "putty" appearance and is homogenized. Grindometer (DIN norm 53203) is used to determine the size of polyethylene wax crystal clusters. Accumulations must not be larger than 20 μ.

14) Bleached linseed oil

It is examined:

- drying

- acid number

- smell

A thin spread (0.2 mm) on a glass substrate should dry in 48 hours.

The acid number (tested according to DIN standard 53402) ranges from 0.2 to 0.4.

The smell of bleached linseed oil must be very mild.

15) Al-linoleate

According to the recipe for Gel-paste, Gel-paste is made and tested under point 9).

16) Mineral oil

It is examined:

- specific weight

- refraction

- viscosity

- boiling point - distillation

17) Co-oxide hydrate

It is examined:

- % metal

- action of sicative (Cosoli 2 ethyl hexoic acid)

- humidity

Co in Co oxide hydrate should be 61%.

The test is carried out using the classic analytical method for determining the metal Co.

The action of the sicating agent from the tested Co oxide hydrate is done by making the sicating agent according to the recipe, and performing the test as under 10).

Moisture is tested by drying in a dryer at 60oC until constant weight.

18) 2-ethyl-hexoic acid

It is examined:

- specific weight

- preparation of Co-sicative

The specific gravity should be 0.826 and it is determined by the method of DIN norm 51757.

The test is carried out according to the regulation described under point 10).

19) Manganese borate

It is examined:

- % metal

- humidity

The percentage of Mn is determined by the analytical method for determining the amount of Mn.

Moisture is tested by drying manganese borate in a dryer at 60oC until constant weight.

20) Hydroquinone

It is examined:

- solubility of hydroquinone in isopropanol and diethylene glycol

- effectiveness of hydroquinone in the form of a "retarder"

The solubility of hydroquinone in isopropyl alcohol and diethylene glycol must be at least 20%. The test is performed by dissolving with stirring at room temperature 20 g of hydroquinone in 80% isopropyl alcohol or ethylene glycol. If the hydroquinone dissolves after a short mixing, it means that it can be used to make a retarder.

The effectiveness of the hydroquinone that is tested is done according to the test under 12).

21) Concrete

It is examined:

- production of transparent paint

- particle size after one pass through the trowel of the transparent paint mixture

The paint is made in the laboratory according to the recipe. The color must be yellowish - transparent.

After one pass of the mixed mixture for transparent paint, the particle size, on the grindometer, should be 0 (DIN norm 53203).

Laboratory control of offset basic colors

For all the basic colors listed, the following tests must be performed - control:

- color intensity

- paint viscosity

- color shade

- size of color transfer

- stickiness, i.e. the inkometer value of the paint

- particle size

For all basic shades, there should be standards in the control laboratory, so that comparative tests always show the same relationship with any deviation of the tested sample.

Table of parameters that characterize a particular color

[image]

Test methods

The shade is determined visually, by comparing prints from the test print machine.

Color strength is tested according to DIN standard 53204.

Paint viscosity is tested with a Laray viscometer, DIN standard 53222.

Testing color transfer, as an important element of offset ink, is best done with a test print machine. A quality offset ink should have a "transfer" of 1.2 - 1.5 g/m2.

Stickiness test, or the so-called income meter values are done on Thwing Albert - INKOMETER.

With this device, we get a numerical unnamed size of the stickiness of the paint, which is very important when printing, especially on machines with a large number of prints. There must be a balance between the necessary stickiness, for the paint to transfer from roller to roller, and finally to the paper, and the stickiness of the paint, which can damage the paper at higher speeds.

This phenomenon greatly affects the quality of the print, and one of the biggest tasks in this work was to make such a color that a combination of binders, pigments and rheological additives achieves a high quality of print.

The size of the paint particles is determined according to DIN standard 63203.

The size of the ink transfer on the machine for test prints

0.2 cc of paint is applied to the scouring rollers with a micro pipette. The paint is rubbed on these rollers for 30 seconds. After scrubbing, the color is transferred to the impression form for 30 seconds as well. The form on which the paint has been applied is weighed and after that a print is made on paper with the form.

The form, from which the print was made, is weighed again and the transfer size in g/m2 is calculated from the difference.

Determining the stickiness of graphic paint - incometer value

Instrument: Thwing Albert – INCOMETER

This instrument determines the numerical unnamed value of stickiness, i.e. the incometer value.

The temperature of the roller on the instrument should be 33oC. A strictly defined amount of paint (1.4 cc) is applied to the rollers of the instruments using a pipette. The roller system consists of rollers coated with rubber and one metal roller, through which water flows from the thermostat in order to maintain the test system at a set temperature.

The paint applied to the upper roller of the instrument is rubbed on the roller system at a speed of 1200 rpm. Scrubbing at this speed takes 1 minute. In this way, a uniform layer of paint was created on the rollers. After scrubbing, the speed is reduced to 400 rpm and at that speed, the stickiness is measured by adjusting the weight on the balance lever, until balance is reached.

Claims (10)

1. Offset inks, for paper and cardboard printing, indicated by the fact that they contain 15-20% pigment, 10-15% alkyd resin, 5-10% wax paste, 2% offset gel, 1-2% surface dryer, up to 2% deep dryer, and 49-65% of the characteristic binding component for a certain group of colors. 2. KARTOSET paints indicated by the fact that their binding component is made on the basis of modified rosin, alkyd, linseed and mineral oil. 3. Offset paints (group 22) characterized by the fact that it has two types of binding components, namely component A made by dissolving rosin in mineral oil and component B composed of resin dissolved in linseed and mineral oil. 4. Offset colors (group 26) characterized by the fact that it has two types of binding components A and B (as under 3), but the oil used is poor in smell. 5. Chromofresh colors (group 38), indicated by the fact that the ratio of resin: mineral oil in binder component A is 45:55, and that binder component B contains isotridecyl alcohol. 6. All types of offset paints characterized by the fact that they contain linseed oil alkyd with an acid number of 5.2 and tolerance to AF oils of 737%. 7. In the formulations of offset colors, there is also an offset gel indicated by the fact that it contains Al linoleate, linseed and mineral oil. 8. Surface drier - Co sicable indicated by the fact that cobalt oxide hydrate is dissolved in organic hydrocarbon acid and mineral oil. 9. Deep dryer - Sprimol paste characterized by the fact that Mn borate dissolves in linseed oil, and contains benton, linseed oil alkyd, mineral oil. 10. A retarder characterized by the fact that it contains Zuinol dissolved in diethylglycol for the purpose of preventing the drying of colors in the mass.