Hospitals 

A sheet of paper has the following size features. Cardboard. Paper. Company "Bereg" - coated paper, designer paper, designer cardboard. Sorption capacity of paper

The properties of paper determine its appearance, quality and purpose. These include - structural, geometric, mechanical, optical, chemical, electrical and properties determined using a microscope.

The structural and geometric properties of paper include parameters such as weight, thickness, smoothness, bulk, lumen and porosity.

The mechanical properties of paper can be divided into strength and deformation properties. Deformation properties are manifested when external forces act on the material and are characterized by a temporary or permanent change in the shape or volume of the body. During the main technological operations of printing, paper is subjected to significant deformation of the paper, for example: stretching, compression, bending.

The main indicators of optical properties are: whiteness, opacity, transparency (opacity), gloss and color.

The chemical properties of paper are determined mainly by the type of wood used, the method and degree of pulping and bleaching, as well as the type and amount of non-fibrous components added, and are important because they determine the physical, electrical and optical properties.

Structural and geometric properties. According to GOST R53636-2009 “Pulp, paper, cardboard. Terms and Definitions"

Mass or weight.

The mass (or weight) of one square meter of paper is the most common indicator, since most papers are sold by weight of 1m 2. The mass of paper is more often referred to as a unit of area than to a unit of volume (as is done with respect to other materials), because paper is used in the form of a sheet and area in this case plays a more important role than volume. According to the accepted classification, the mass of 1 m 2 of printed paper can be from 40 to 250 g. Papers weighing more than 250g/m2 are classified as boards.

Thickness

The thickness of the paper, measured in microns (µm), determines both the permeability of the paper in the printing press and the consumer properties - primarily strength - of the finished product.

Smoothness

Smoothness characterizes the state of the surface of the paper, due to mechanical finishing, and determines the appearance of the paper - rough paper, as a rule, is unattractive in appearance. Smoothness is important for writing papers, for printing papers, and also when gluing paper.

The opposite of smoothness is roughness, which is measured in microns (µm). It directly characterizes the microrelief of the paper surface. One of these two values ​​is always present in paper specifications.

Bulk

Bulkness is measured in cubic centimeters per gram (cc/g). The bulk of printed papers ranges on average from 2 cm 3 /g (for loose, porous) to 0.73 cm 3 /g (for high-density calendered papers). In practice, this means that if you take a thicker paper of a smaller gram, then with equal opacity there will be more sheets in a ton of paper.

Clearance

The clearance of paper characterizes the degree of uniformity of its structure, that is, the degree of uniformity of the distribution of fibers in it. The lumen of the paper is judged by observation in transmitted light. Paper with a highly cloudy gap is extremely inhomogeneous. Its thin spots are also the least durable and easily pass water, ink, printing ink. Due to the uneven perception of the printing ink by the paper, printing on cloudy paper is of poor quality.

Paper with a cloudy gap is difficult to color, multi-tone clouds are formed. Thick sections of the paper web are colored more intensively and less intensively thin ones.

Porosity

Porosity directly affects the absorbency of the paper, that is, its ability to accept printing ink, and may well serve as a characteristic of the structure of the paper. Paper is a porous capillary material; at the same time, macro- and microporosity are distinguished. Macropores, or simply pores, are spaces between fibers filled with air and moisture. Micropores, or capillaries, are the smallest spaces of indefinite shape penetrating the coating layer of coated papers, as well as spaces formed between filler particles or between them and the walls of cellulose fibers in uncoated papers. There are also capillaries inside cellulose fibers. All uncoated, not overly compacted papers, such as newsprint, are macroporous. The total pore volume in such papers reaches 60% or more, and the average pore radius is about 0.160.18 µm. Such papers absorb paint well due to the loose structure, that is, the highly developed inner surface.

Mechanical properties

Mechanical strength.

The tensile strength of paper does not depend on the strength of individual components, but on the strength of the paper structure itself, which is formed during the paper production process. This property is usually characterized by breaking length in meters or breaking force in Newtons. So, for softer printing papers, the breaking length is at least 2500 m, and for hard offset papers this value increases to 3500 m and more.

Break resistance.

The fracture resistance index depends on the length of the fibers from which the paper is formed, on their strength, flexibility and on the bonding forces between the fibers. Therefore, the highest fracture resistance is characterized by paper, consisting of long, strong, flexible and tightly bonded fibers.

Burst resistance.

This indicator is of great importance for wrapping papers. It is related to the breaking load of paper and its elongation at break.

Extensibility.

Paper elongation to break, or its extensibility, characterizes the ability of paper to stretch. This property is especially important for packaging paper, sack paper and cardboard, for the production of stamped products, for the base of waxed paper used for automatic wrapping.

Softness.

The softness of paper is related to its structure, that is, its density and porosity. Thus, large-pore newsprint can deform under compression up to 28%, and for dense coated paper, the compression deformation does not exceed 68%.

Linear deformation when moistened.

The increase in the dimensions of a wetted sheet of paper in its width and length, expressed as a percentage of the original dimensions of a dry sheet, is called linear deformation when wetted. The values ​​of paper deformation when wet and permanent deformation are important indicators for many types of paper (for offset, chart, cartographic, for the base of the photo substrate, for paper with watermarks). High values ​​of these indicators lead to misalignment of ink contours during printing and, as a result, to low-quality printing. However, it should be noted that in GOST 12057-81 “Paper and cardboard. Methods for determining linear deformation.» very stringent test conditions are laid down (wetting a calibrated strip of paper for a certain time), the use of which is impractical for most printed types of paper. European standards suggest the use of the term "moisture expansion", which determines the change in the linear dimensions of a strip of paper when the air humidity changes from 30 to 80%. High humidity dramatically reduces the mechanical tensile strength of the paper.

Optical properties

optical brightness.

Optical brightness is the ability of paper to reflect light diffusely and evenly in all directions.

White.

The true whiteness of a paper is related to its luminosity or absolute reflectivity, i.e. visual efficiency. Whiteness is based on the measurement of light reflection by white or almost white papers with one wavelength (GOST 30113-94 "Paper and cardboard. Method for determining whiteness." Provides 457 millimicrons, that is, in the visible spectrum) and is defined as the ratio of the amounts of incident and distributed reflected light (%).

Yellowing.

Paper yellowing is a term that conventionally refers to the decrease in its whiteness due to exposure to light rays or elevated temperature. Paper can be protected from light damage by storing it in a room without windows or with windows covered with thick curtains.

Opacity, or opacity.

Opacity is the ability of paper to transmit light rays. The opacity property of paper is determined by the total amount of light transmitted (diffuse and non-diffuse). Opacity is usually determined by the degree of penetration of the image into the material under test, placed directly opposite the object in question.

The term "paper opacity" is more commonly used - the ratio of the amount of light reflected from a sheet lying on a black substrate to the light reflected by an opaque stack of this paper.

Transparency

Transparency is related in some way to opacity, but differs from it in that it is determined by the amount of light that passes through without scattering. The transparency ratio is a better estimate of highly transparent materials (cripples), while the opacity measurement is more suitable for relatively opaque papers.

Gloss or gloss.

Gloss (gloss) is a property of paper that expresses the degree of glossiness, gloss, or the ability of a surface to reflect light falling on it. This indicator can be thought of as the property of the surface of the paper to reflect light at a given angle. Thus, gloss (gloss) can be characterized as the ratio of the amount of light reflected in the specular direction to the amount of incident light.

Chemical properties.

Wet strength.

The wet strength of paper is judged by the degree to which it retains its original strength in the wet state, that is, according to the strength that it had before wetting, being in the air-dry state.

Humidity.

Ash content.

The ash content of paper depends on the quantitative content of fillers in its composition. High-strength paper should have a low ash content, as minerals reduce paper strength.

Paper weight is measured by the weight of one square meter (g/m2) and varies depending on the destination from 40 to 250 grams. When printing newspapers or magazines on sheet-fed offset machines, it is recommended to use thicker grades of paper (at least 80 g/m2), it is advisable to use thin grades of paper in role-rotating machines: newspapers - about 50 g/m2, books - 60-80 g/m2 . One of the most important properties of paper is smoothness. The higher this indicator, the tighter the contact of the paper web with the printing form and the ability to reproduce thin strokes without distortion. The smoothness of paper is determined on a special device and is characterized by the time of expiration of a specified volume of air between a paper sample and a smooth plate tightly pressed against it; measured in seconds. Newsprint cannot be smooth, as it contains a lot of wood pulp, and therefore it is porous. Intaglio printing (300-500 sec) has the highest requirements for paper smoothness, while offset paper has an average level of smoothness of 80-150 sec).

The degree of compaction of paper affects its bulk (thickness). The higher this indicator, the higher the degree of opacity. As a rule, the largest bulkiness is 2 cm3/g, the smallest is 0.7 cm3/g.

The porosity index indicates the degree of absorption of the printing ink by the paper. Macro- and micropores are formed between the fibers, therefore loose grades of paper, such as newsprint, are called macroporous (the pore radius can vary from 0.16 microns to 0.18 microns), and compressed coated papers are called microporous (with a pore size of about 0.03 microns). This indicator is important to take into account already at the prepress stage of preparing the graphic material, since it most of all affects the value of the dot gain. If you want to get saturated colors, you need to choose paper with the lowest porosity.

For legibility, it is necessary to create a brightness difference between the black ink and the color of the unprinted areas of the paper. Therefore, the higher the whiteness value, the greater the contrast can be achieved. Cellulose fibers have a yellow tint, which is sometimes eliminated by adding a blue dye of the opposite color. The whiteness of newsprint is about 60%, offset - about 70%, and coated - more than 80%.

One of the main properties of paper for printing is opacity. For an optimal level of opacity, a combination of a mixture of unmilled pulps from different tree species is necessary. It has been established that paper samples consisting of 30% unmilled softwood pulp and 70% hardwood pulp have a more uniform gap, the length of the main part of the fibers of these samples is from 0.4 mm to 1.0 mm. In samples with poor lumen, about 10% of fibers longer than 1 mm are present. Coated papers have an opacity level of more than 90%, newsprint - from 50%.

The paper softness setting is important for choosing the printing method. For example, under high pressure from embossed letterpress printing plates, the paper should provide the greatest contact with the printing plate, that is, be soft and quickly recover from deformation. Embossing paper should have completely opposite indicators.

Paper intended for offset printing has increased moisture resistance; for this, special hydrophobic substances are introduced into its composition. Otherwise, when the printing plate is moistened and moisturizing solutions get on the printed material, the paper web will deform, which will lead to loss of strength and the effect of ink mismatch in full-color printing.

Zaitsev Danil

This work is devoted to the description of the properties of paper. In the course of practical research, these properties were determined.

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Chapter 2. Practical part

2.1. Description of experiences.

Purpose: to determine the quality of paper (color, smoothness, strength, thickness) and properties (absorbs water, wrinkles, cuts, burns, etc.)

Equipment and material: different types of paper, scissors, matches, water containers.

Let's experiment with some types of paper and find out which one has the best characteristics. The main properties of paper are strength, elasticity, plasticity, light resistance, etc.

  1. Experience No. 1 Smoothness.I took different sheets of newsprint, offset, parchment, photo paper and noticed that it was mostly smooth. The appearance of the paper depends on the smoothness.

Conclusion: Smoothness is important for writing papers, for printing papers, and also when gluing paper.

Conclusion: Paper is made up of fibers that make the paper strong.

Conclusion: Paper comes in different textures: thick and thin. Translucent paper depends on the compaction of the fibers.

  1. Experiment No. 4 Porosity.On a sheet of paper I dripped paint, it was absorbed. There are pores between the fibers.

Conclusion: Paper absorbs ink due to its porosity.

Conclusion: Paper folded like an accordion becomes more durable. The principle of "accordion" is used in the manufacture of boxes.

  1. Experience No. 6 Extensibility.I take a sheet of soft paper (napkins) and try to stretch it, the paper slowly stretches a little.

Conclusion: The paper is stretched. This property is especially important for wrapping paper.

  1. Experience No. 7 Softness.I try to crumple a sheet of paper into a ball, the paper lends itself easily. Conclusion: Paper is soft, softness depends on its density.

Conclusion: The stronger the paper before wetting, the less it loses its shape after wetting.

  1. Experience No. 9 Combustion.I try to set fire to the paper, it burns easily. Burning paper leaves ashes, ash.

Conclusion: Paper is highly flammable and burns very well.

Let me summarize our research:I have listed the main properties of paper. They need to be known to those people who make paper. Paper mills make different types of paper. Quality depends on its properties.


2.2. Research results. Conclusions.

In the course of the experiments, we crumpled the paper, tore it apart, pulled the edges in different directions, cut it, and put it in a bowl of water. They burned paper. Cut the paper with scissors.

We summarized the results of experimentation and named the various properties of paper.

As a result of mechanical action, we saw that paper:

Wrinkled;

Tears;

bends;

twisted;

cut;

Lit;

Absorbs water.

Conclusion.

As a result of the study, we learned the history of the emergence of paper. In the course of our research, we read more than 10 different articles, stories on a topic of interest to us, searched for the necessary information on the Internet. It turned out that there is paper for printing, colored paper, writing paper, absorbent paper, cardboard.

We learned that there are different properties of paper: structural and geometric (mass, thickness, smoothness, coating, bulk, lumen, porosity), mechanical (mechanical strength, fracture resistance, bursting resistance, extensibility, softness, deformation when moistened), optical (brightness , whiteness, yellowing, opacity, gloss), chemical (wet strength).

We learned to observe, summarize the knowledge gained and draw conclusions. We conducted a series of interesting experiments to identify the properties of paper and found out that:

  • The paper is crumpled, while the fibers from which it is made break, so it does not subsequently take on its original form;
  • If the paper gets wet, it will warp;
  • In order for the paper to warp, there is enough water contained in the glue. (this property is important to know when making paper applications);
  • Paper is plastic;
  • Paper is a fragile material;
  • Paper burns out.

In the course of our study, all the tasks set were achieved. As a result of research work, we came to the conclusion that paper is an amazing material, one of the most accessible, we encounter it daily. Looking around, we found out that books, newspapers, wallpapers, various packaging are all paper. It turned out that there are a huge number of types of paper. We found out that, knowing the properties of paper, the sheet becomes obedient to the hands, and you can create very interesting compositions using such types of paper work as appliqué and paper-plastic.

LITERATURE

Aleksin A. G., Alekseev S. P. “What is it. Who is "Encyclopedia 3rd edition. M.: Pedagogy, 1990. vol. 1. pp. 189-190

Bubnova E. New Encyclopedia of a Schoolchild, M .: Makhaon, 2003. - 383 p.: ill.

Geronimus T.M., "Little Master" textbook on labor training. 1 class. M.: Ast-press school, 2005 p. 128

Daukevich V. "How a book is made" M .: Children's literature, 1987. page 25

Zubkov B.V. "A book about a book" M .: Malysh 1984 pp. 9-11

Zubkov B.V., Chumakov S.V. "Encyclopedic Dictionary of a Young Technician" M .: Pedagogy, 1980. pp. 63-65

Knunyants I.L. Chemical Encyclopedia: in 5 volumes: vol. - M .: Sov. Encyclopedia, 1988. - 623 p.

Likum A. “Everything about everything. Popular encyclopedia for children. M.: Slovo., 1993. volume 1 pp. 200-204

Likum A. “Tell me why. Popular encyclopedia for children "M.: Bustard, 1997. volume. 1 pp. 123-124

Madguik U., Kerrod D. "The Book of Knowledge in Questions and Answers" M .: Makhaon 2003. page 70

Ovchinnikova O.O. Popular encyclopedic illustrated dictionary.

Internet sources.

www.itype.ru

www.bestreferat.ru

www.poigrat.net

www.chelny-bumaga.ucoz.ru

www.wikipedia.ord

Lecture 6

Physical properties of paper

The physical properties of paper include the mass of a square meter, thickness, density, porosity, bulkiness.

For determining mass of a square meter paper, a rectangle of the appropriate size is cut out of paper, weighed, and then recalculated to the mass of one square meter.

Paper density defined as the ratio of the mass of the paper sample to the volume (g/cm3).

Paper thickness usually ranges from 0.03 to 0.25 mm. Cardboard - up to 3 mm. Determination of paper thickness is carried out using a thickness gauge. For practical purposes, take 10 sheets of paper, measure their thickness and divide by 10.

The porosity of paper is the ratio of the size of the pores to the total volume of the paper. Porosity is expressed in %. Since paper is made from fibers of various sizes, the formation of the following types of pores is possible in it:

§ through;

§ dead ends;

§ closed;

§ ring.

Determination of porosity is carried out using various porometers.

In practice, porosity is determined by the formula:

Pore ​​\u003d (1-d / 1.5) * 100%, where d is the density of the paper.

The porosity of various types of papers ranges from 30-70%: tracing paper - 30%, newsprint - 70%.

Porosity can be used to control the drying speed of certain types of printing inks.

In practice, not only porosity is more important, but also the size distribution of pores. The smaller the difference between the smallest and largest pores, the better the image quality will be (narrow pore size distribution).

Puffiness is the reciprocal of density; unit of measure is cm3/g. The amount of bulk is often given in certificates for paper from foreign manufacturers.

… depends on:

§ direction of fiber distribution in a paper sheet (anisotropy). In the longitudinal direction, the strength of the fiber is higher;

§ Strength of an individual fiber. The strength of an individual fiber depends on the method of obtaining, the type of wood, the degree of grinding;

§ the presence of hydrogen bonds. If the compound has N, O, F, then hydrogen bonds can form. Hydrogen bonds are formed between molecules that have N, O or F atoms and H atoms in their composition. Hydrogen bonds themselves are very weak, but the cellulose molecule contains millions of hydroxyl groups and therefore the total effect of hydrogen bonds can provide the strength of the paper sheet. A simple experiment can be done to prove the effect of hydrogen bonding on paper strength. To do this, the paper sheet must be soaked in water, alcohol and mineral oil. In the first case, the strength of the paper is the smallest, in the latter, the greatest. In the 1st case, water molecules will destroy the hydrogen bonds between cellulose molecules. In the latter case, mineral oil does not contain N, O, F, and therefore the strength of the paper will not change. If the paper begins to dry, then hydrogen bonds will form again between the cellulose molecules and the strength of the paper will increase.


§ Humidity of the surrounding air. Therefore, all measurements of paper properties are carried out under standard conditions at a relative humidity of 60-65%.

In practice, a number of the following indicators are used to characterize the strength of paper:

1) zero breaking length;

2) breaking length;

3) elongation.

BREAKING LENGTH - an indirect value that characterizes the length of a strip of paper, which, being suspended at one end, will break under its own weight. The breaking length is measured in meters (rarely km). For most printing papers, the breaking length should be greater than or equal to 3000-3500mm.

In practice, the breaking length is determined on a tearing machine by tearing a strip of paper under certain conditions. Then the breaking load, at which the break occurred, is recalculated according to the formula to the breaking length. To determine the breaking length, the clamps of the machine are spaced 100 mm apart.

If the clamps of the tensile testing machine are as close as possible, then determine the ZERO BREAKING LENGTH. It characterizes the strength of individual fibers. Since the zero breaking length is higher than the breaking length, the strength of the individual fibers is higher than the strength of the paper sheet.

RELATIVE ELONGATION EXTENSIBILITY)

Elongation = (Dl/l)*100% (1)

When the paper is torn, it lengthens. This elongation is defined as elongation at break and is calculated by Formula 1. The elongation value for paper is 1-5%. It is known from the theory of resistance of materials that the higher the extensibility, the more stable the strength properties of materials operating under stress. Thus, the higher the stretch, the lower the paper breakage in printing.

In practice, to increase extensibility, they try to raise the relative humidity of the paper from 5-6% to 7-8%.

In practice, in addition to the breaking length and relative elongation, the following types of paper tests are used:

§ fracture resistance;

§ tear resistance;

§ sheet edge resistance;

§ bursting resistance;

§ ring compression test;

§ determination of stiffness in static bending;

§ resistance to delamination;

§ loss of mechanical strength during aging of paper.

1. FRAGMENT RESISTANCE is measured on a strip of paper as it is stretched. In this case, the paper sample is bent back and forth at an angle of 180. One back and forth movement is called double kink, and the fracture resistance is measured in c.f.p. - the number of double kinks.

Most printing papers have a break resistance greater than or equal to 1012 p.f. And only cartographic types of paper and the so-called "special" types of paper are characterized by a fracture resistance greater than or equal to 40-100 h.f.p.

2. TEAR RESISTANCE is characterized by the force that causes tearing of pre-cut paper along the edge to a certain length. The test is carried out on 4 pieces of paper, which are pre-cut along the edge and then cut with a pendulum-type knife.

For printed papers, this figure is used in the newsprint standard.

Close in essence to tear resistance is the index RESISTANCE TO TEAR OF THE SHEETS EDGE. It is characterized by the force that must be applied to tear the edge of the sheet. This indicator is important for printing cardboard used for the manufacture of playing cards.

Characterizes strength paper clamped around the ring, force directed perpendicular to its surface. Basically, this indicator is used to evaluate cardboard.

Determination of stiffness in static bending consists in determining the force applied to the free end of a cantilevered cardboard sample and bending it through a certain angle.

Ring compression test- provides for the measurement of the breaking force during axial compression of a strip of paper placed on the edge and rolled into a ring.

Peel resistance test: is to determine the force required to delaminate the test sample.

Definition loss of mechanical strength during aging. It consists in keeping a paper sample in an air thermostat at a temperature of 150 degrees for a certain time and measuring standard strength indicators. The loss of strength is expressed as a percentage of the original. And the index of fracture resistance has the greatest sensitivity to aging. To characterize paper aging, whiteness loss is determined in a similar manner.

The printing properties that define it can be combined into the following groups:

Geometric: smoothness, thickness and weight of 1 m 2, density and porosity;
Optical: optical brightness, opacity, gloss;
Mechanical (strength and deformation): surface plucking strength, breaking length or tear strength, fracture strength, tear resistance, delamination resistance, stiffness, compressive resilience, etc.
Sorption: wet strength, hydrophobicity, ability to absorb printing ink solvents.

All these indicators are closely related to each other. The degree of their influence on the assessment of the printing properties of paper is different for different printing methods.

Paper is often classified by the degree of surface finish. It can be unfinished paper - matte, machine smooth paper and glazed (otherwise calendered) paper, which was additionally processed in supercalenders to give it high density and smoothness.

Geometric Properties paper

(In a practical application, this means that if you take a thicker paper of a smaller gram, then with equal opacity, there will be more sheets in a ton of paper)

Porosity directly affects the absorbency of paper, that is, its ability to accept printing ink, and may well serve as a characteristic of the structure of the paper. Paper is a porous-capillary material, while macro- and microporosity are distinguished. Macropores, or simply pores, are spaces between fibers filled with air and moisture. Micropores, or capillaries, are the smallest spaces of indefinite shape penetrating the cover layer of coated papers, and also formed between filler particles or between them and the walls of cellulose fibers in uncoated paper. There are also capillaries inside cellulose fibers. All uncoated, not overly compacted papers, such as newsprint, are macroporous. The total pore volume in such papers reaches 60% or more, and the average pore radius is about 0.16-0.18 µm. Such papers absorb paint well, due to their loose structure, that is, a highly developed inner surface.

A special place in the structure of the printing properties of paper is occupied by optical properties, that is, whiteness, opacity, gloss (gloss).

Optical brightness is the ability of paper to reflect light diffusely and evenly in all directions. High optical brightness for printed papers is highly desirable, since the clarity, readability of the publication depends on the contrast of the printed and blank areas of the print.

With multi-color printing, the color accuracy of the image, its correspondence to the original is possible only when printing on sufficiently white paper. To increase the optical brightness, so-called optical brighteners - phosphors, as well as blue and violet dyes, which eliminate the yellowish tint inherent in cellulose fibers, are added to expensive high-quality papers. This technique is called highlighting. Thus, coated papers without optical brightener have an optical brightness of at least 76%, and with optical brightener - at least 84%. Printed papers containing wood pulp should have an optical brightness of at least 72%, but newsprint may not be white enough. Its optical brightness averages 65%.

Another important practical property of printed paper is its opacity. Opacity is especially important for duplex printing. To increase the opacity, a composition of fibrous materials is selected, their degree of grinding is combined, and fillers are introduced.

The next group of printing properties is the mechanical properties of paper, which can be divided into strength and deformation. Deformation properties are manifested when external forces act on the material and are characterized by a temporary or permanent change in the shape or volume of the body. The main technological operations of printing are accompanied by significant paper deformation, for example: stretching, compression, bending. The normal (uninterrupted) course of technological processes of printing and subsequent processing of printed products depends on how paper behaves under these influences. So, when printing with a high method from rigid forms at high pressures, the paper should be soft, that is, it should be easy to compress, level out under pressure, providing the most complete contact with the printing plate.

Sorption properties paper

Finally, we come close to one of the most important properties of printed paper - its absorbency. The correct assessment of absorbency means the fulfillment of the conditions for the timely and complete fixing of the ink and, as a result, obtaining a high-quality print.

absorbency paper, primarily depends on its structure, since the processes of interaction between paper and printing ink are fundamentally different. Before talking about the features of this interaction in certain cases, it is necessary to recall once again the main types of structures of modern printed papers. If we depict the structure of paper in the form of a scale, then macroporous papers consisting entirely of wood pulp, for example, newsprint, will be placed at one of its ends. The other end of the scale, respectively, will be occupied by pure cellulose microporous papers, for example, coated papers. A little to the left will be pure cellulose uncoated paper, also microporous. And everyone else will take the rest of the gap.

Macroporous papers take ink well, absorbing it as a whole. The colors are thin here. Liquid paint quickly fills large pores, absorbing to a sufficiently large depth. Moreover, its excessive absorption can even cause the “breakthrough” of the print, that is, the image becomes visible from the defense side of the sheet. Increased macroporosity of paper is undesirable, for example, in illustrative printing, when excessive absorbency leads to loss of saturation and glossiness of the ink. Microporous (capillary) papers are characterized by the so-called “selective absorption” mechanism, when, under the action of capillary pressure forces, mainly a low-viscosity paint component (solvent) is absorbed into the micropores of the surface layer of the paper, while the pigment and film former remain on the surface of the paper. This is exactly what is required to obtain a clear image. Since the mechanism of paper-ink interaction in these cases is different, for coated and uncoated papers, various paints are prepared.