Questions and answers
Preparing to work as a laminator operator
1. Turn on the laminator and set the preliminary heating temperature to 75-80 °C. The temperature regime must be taken into account when setting the lamination speed: the higher it is, the higher the temperature. 2. Familiarize yourself with the technical specifications and prepare the necessary film. 3. Check that there is no dirt on the pressure shafts. 4. Check whether the prints are completely dry after printing.
It is advisable to wait a day to be completely sure that the paint has hardened. There should be no powder on the sheets. If there is powder on the sheets, take measures to remove it.
5. For thin paper – prepare and adjust the roll for rewinding the product into a roll to align the sheets after lamination to the product format. It is strictly not recommended to work without a reverse winding device if there is a risk of curling of product sheets.
6. Place the film on the laminator and adjust its tension.
7. The tension of the film web should be minimal. Strong tension leads to stretching of the film and curling of the product, while weak tension leads to wave formation, wrinkling when the film is brought to the roller and the possibility of its sticking to the roller.
1. Place the make-up sheets of the run on the work table and run the film through. 2. Turn on the minimum lamination speed. 3. Set the pressure to 3-4 units. 4. When adjusting the pressure on the heating rollers of the laminator, you must remember that if the heating rollers are in a heated state and the lamination process is not carried out, the pressure must be turned off, i.e. the shafts must be separated.
Keeping heated rollers together in such situations can lead to damage and deformation of the rubber of the laminator rollers! 5. Laminate several sheets, release the pressure and stop the laminator. 6. Visually assess the quality of the laminated sheets: the film should not peel off at the fold of the sheet, there should be no bubbles or silvering, the film should not come away from the material.
With good lamination, the film is difficult to tear off from the material even with force. The print must be free of marks, scratches and wrinkles. If necessary, we make corrections for pressure (but not more than the seventh division) and temperature. The choice of optimal lamination modes largely depends on the thickness of the laminated product, climatic conditions in the workshop, and lamination speed. REMEMBER: too high pressure on the rollers, temperature, and tension of the film web lead to defects. 7. After lamination is completed, carefully remove dirt and film residues from the rollers and clean the work area.
Lamination temperature and speed
Determining the ideal temperature requires experience. By the time the film comes into contact with the pressure roller, the film-to-paper adhesion temperature must be reached. If the laminator runs too fast, the film will not adhere to the material. The lamination speed depends on the temperature of the heating roller.
The optimal balance varies for different papers and films. The temperature is also determined by the characteristics of the film itself (manufacturers indicate the temperature in the technical specifications – it ranges from 70 degrees to 105 degrees for matte films and from 70 degrees to 110 degrees for glossy films)
Lamination. Problems and solutions
Problem: Film Wrinkling
Cause: Weak web tension; Solution: Tighten the canvas.
Reason: Incorrect threading of the fabric; Solution: Check the web wiring.
Cause: Incorrect installation of the pressure rollers; Solution: Check the installation of the shafts.
Cause: Insufficient temperature; Solution: Wait for the laminator to fully heat up; if necessary, increase the temperature or use a thinner film.
Problem: Paper Wrinkling
Cause: The sheet enters the laminator unevenly (the leading edge of the sheet should be parallel to the axis of the laminating rollers); Solution: Smooth out the sheet and reinsert it into the laminator.
Problem: Bubbles under the film
Cause: Weak web tension; Solution: Tighten the canvas.
Cause: Insufficient temperature; Solution: Wait for the laminator to fully heat up; if necessary, increase the temperature or use a thinner film.
Cause: Insufficient lamination pressure; Solution: Increase lamination pressure
Reason: Incorrect web threading; Solution: Check the web wiring.
Cause: Incorrect installation of shafts; Solution: Check how the shafts are installed.
Problem: Regularly recurring defects
Cause: Contamination of the laminating rollers; Solution: Clean the shafts.
Problem: Laminate waviness and print curling
Cause: Excessive heating temperature; Solution: Reduce the heating temperature of the shafts.
Cause: Incorrect installation of shafts; Solution: Check that the shafts are installed correctly.
Cause: High web tension; Solution: Reduce web tension.
Checking the quality of lamination: make several circulation sheets, let them cool for about 10-15 minutes and check the quality of lamination for repeated creasing and folding. The film should not lag behind the paper. If everything is fine, proceed to the process of mass industrial lamination.
The geometry of the paper surface is characterized by its smoothness or roughness.
The “surface geometry” of paper is determined not only by micro-irregularities, but also by macro-irregularities. The former are determined by microgeometry, the latter by the distribution of mass over the area.
There is a group of most common methods in which smoothness is measured using air flow.
The most common measurement methods are Bendtsen Sheffield and Parker (roughness). Becca (smoothness).
The essence of the Beck method is to measure the time required for air of a certain volume to pass into a vacuum chamber between the surfaces of the test sample and a polished glass plate of a certain area, pressed with a certain pressure. Smoothness is measured in seconds. The higher the smoothness, the greater the value of the indicator.
There are no strict relationships between the values of smoothness (roughness) indicators measured by different methods. There is a qualitative relationship between the Beck smoothness and Bendtsen roughness values.
The Bendtsen and Sheffield instruments measure the flow of air passing at constant pressure between the surface of the ring and a sheet of paper.
Bendtsen roughness is expressed in ml/min, Sheffield in Sheffield units.
The figures show qualitative relationships between parameters determined by different methods. They make it possible to evaluate the nature of changes in one parameter depending on changes in another and can help in comparing the smoothness and roughness of samples measured by different methods.
The Parker method (PPS) is used to measure the roughness of paper and cardboard under conditions similar to those of a printing press. The Parker roughness measurement result is expressed in microns.
A drop of theory
Light is electromagnetic waves emitted by a source. These waves are of different lengths, and people perceive them partially. We also do not see infrared and ultraviolet radiation. The human eye reads waves reflected from objects and turns them into shapes and colors. Different objects reflect waves in different ways: some well, others poorly, and others partially.
Science has proven that each color has its own wavelength. The reflection or absorption of a frequency is perceived by the brain as a corresponding color. When an object uniformly reflects all waves equally, we see white, and when completely absorbed, we see black.
Since childhood, we know: if you mix yellow with blue, you get green. All this is coloristics – the science of color, Oswald’s color wheel will help you.
It shows that opposite colors cancel each other out. So, red neutralizes green, blue neutralizes orange, and then in a circle: yellow neutralizes violet, and green neutralizes red. This circle is actively used by hairdressers to neutralize unwanted shades when dyeing hair.
The same goes for parsley with paper: its whiteness depends on the components included. One of them is lignin, I talked about it in previous articles, its color ranges from light cream to brown. If the paper is not bleached, it will turn brown, then it will be used to make kraft paper and cardboard.
Remember, they used to use blue dye to whiten clothes? The same principle applies to paper.
For a white sheet to be perceived this way, it must simultaneously reflect the total number of electromagnetic waves across its entire plane. To do this, they use the same blue additives, including fluorescent ones, which neutralize the yellow color. They reflect a larger number of rays hitting the sheet.
When you need to know paper weight
Imagine for a second: one sunny morning you decide that it is no longer possible to procrastinate, the company needs leaflets, employees business cards, and the accounting department needs a corporate quarterly calendar. Two calendars. And then you pick up the phone and bravely dial the printing house’s number. The dialogue with the manager is easy and relaxed, you almost relax, and suddenly at the other end of the line they ask a question:
—What is the thickness of the paper?
Still not understanding that this is addressed to you, you hesitantly ask again:
– Well, density. 130 grams, 150 grams chalk?
Feeling cheated (all this time the paper was thick and you didn’t know it):
– Uh… Well, let’s use the regular one, – a little doubting that there is a regular thickness of paper. Somewhere on the other end of the line, the manager sighs. And says:
—For what purposes do you need leaflets?
It seems they want to steal trade secrets, and probably sell them at exorbitant prices to competitors! There is simply no other way out.
-Pshsh, pshsh! It’s hard to hear! The connection is interrupted, and you hang up. Let us live without leaflets, but the accounting department will now print out a calendar on the printer… Two calendars.
When I came to work at the printing house, it seemed to me that everyone around me had gone crazy and the thickness of paper was measured in mass units. After some time, I realized that when talking with clients, managers miss the second part of this construction – it would be more correct to say “gram per square meter”, calling the unit of measurement of density.
To explain in simple words, the density of paper is how much its square meter weighs in grams. When a printing house talks about 115 grams, it means that if you put a sheet of paper measuring one meter by one meter on a very sensitive scale, they will show those same 115 grams.
However, it’s unlikely that you keep ultra-sensitive scales and several square meters of paper of different densities at home in order to estimate how thick the booklets or leaflets you need. That’s roughly what I thought – and I went for more understandable answers.
Lamination is easy! [article specially for sheenn]
| Post-press and finishing technologies
The end is the crown of the matter. We discuss everything related to cutting, gluing, stitching.
In this article I will look at one simple device that is found in almost every printing house – a laminator or equipment for pressing film. It is necessary to note that for all its apparent simplicity, this equipment and the technological process itself raise many questions and problems for beginners and can be a real disaster when the entire circulation goes into the trash.
Many newcomers come to me with questions: “Help. Scratches. Stripes! . The film peels off. The sheets are curled. “, and sometimes the answers to these questions lie on the surface; you just need to carefully analyze the factors that can influence the occurrence of a marriage. And in this article we’ll talk about them!
All laminators (this article discusses equipment for hot pressing of film) are designed the same and have no fundamental differences from each other. The process of film pressing is shown schematically in Fig. 1, where a special film with a pre-applied adhesive layer, which is melted on a hot “laminating” roller, is glued to the material under pressure created by the printing cylinder.
Everything seemed simple! But in order for this simple process to go off without a hitch, you need to know and take into account the factors that can affect the quality of the product.
Firstly, the condition of the equipment – the laminating roller and the printing cylinder must be clean and the surface of the cylinders must be perfectly flat and smooth: without chips, scratches or other mechanical damage, otherwise we will see “bubbles” on the print. , craters, inclusions.
|Tip: To clean the chrome surface of the laminating roller, it is recommended to use alcohol solutions or household FAIRY. To clean the rubber impression cylinder, use either an alcohol solution or products for cleaning dampening rollers in printing machines. I don’t recommend using regular cleaning solutions because of the slow evaporation time, and they stink.
Secondly, the parameters of pressure, temperature, film tension and operating speed must be correctly set on the laminator. The film tension must be adjusted so that the film on the laminating roller is evenly distributed: too high tension leads to film stretching, and too low tension leads to film wavy formation.
The clamping pressure must be experimentally selected taking into account the thickness of the material and film to ensure good adhesion of the film to the printed sheet (in most cases, the pressure on the pressure gauge is kept at 4-5 divisions). Temperature and speed are also selected based on experimental observations and these parameters are interrelated – the speed of operation depends on the temperature of the laminating roller.
If the laminator runs too fast, the glue will not have time to activate and the film will not adhere to the printed output. In practice, the temperature of the laminating roller is set in the range of 80–120° (for matte it is less, for glossy it is more).
Thirdly, the film for pressing can be different – they differ not only in thickness (from 24 microns to 250 microns), but also in the quality of both the film itself and the quality of the applied adhesive layer. Some simple tips on how to evaluate the quality of a film: 1.
Pay attention to the quality of winding the film onto the sleeve – the film should be wound evenly: without tails along the edges (the end should be smooth), without bumps or waviness. 2. Do not use film with mechanical damage to the roll – broken ends, cuts, dimples and punctures – all this will lead to defective laminated products. 3.
The adhesive layer must be applied evenly over the entire surface of the sheet. Visually assessing such a parameter is very problematic, but there are cases when halos and spots are visible to the naked eye, and this should already be alarming. 4. When further applying UV varnish and foil, care must be taken to use films with a corona (activated) surface.
Fourth, the printing sheets must be suitable for hot pressing of film. It is not recommended to use paper with a density of less than 130gsm, tracing paper, or designer papers with a rough texture for laminating. The quality of adhesion is also largely affected by printing ink – do not use prints printed with inks with a high wax content (this also applies to prints from digital machines that use toner with a high oil content).
Prints must be completely dry and the paper must not be too wet, as upon contact with a hot laminated surface, water particles begin to form on the surface of the material, which disrupt adhesion. It is optimal to start the lamination process 24-48 hours after printing.
|Tip: For prints that are planned to be laminated, it is better to use powders based on sugar (soluble) or starch. It is not recommended to use silicone-coated powders, because… particles of such powder will always be located on the surface of the paint layer and interfere with film adhesion.
When printing, using WD varnishes on printed prints can either help and improve the quality of lamination, or it can do harm. I highly recommend trying it!
Fifth, before starting work, check the quality of the pressing – make several prints, wait 15 minutes and check the quality of lamination by folding the print multiple times – the film should not lag behind the paper.
When sampling, it is necessary to follow the sequence of operations:
- from batch
products select units
- sheets are selected from product units
- sample sheets (samples) are selected and cut from the selected sheets
- in accordance with the requirements of standards for specific test methods, samples are cut
Sheets should not have wrinkles or folds and should be flat. They must be cut from undamaged sheets of products. The edges of the selected sheets must be parallel to the machine and cross direction of the paper. The sample sheets should be approximately (300 x 450) mm in size.
When handling sample sheets, care must be taken to protect them from exposure to sunlight, liquids, changes in humidity and other undesirable influences (GOST Sampling for determining average quality).
To bring test conditions into comparable conditions, paper samples are brought to certain standard conditions for humidity and temperature before testing. And the tests themselves are carried out under these conditions. This bringing of samples to standard conditions is called conditioning.
Conditioning conditions are of three types, as indicated in the table. Conditioning conditions at 50% relative humidity are more commonly used. Special conditions are used, for example, when conditioning banknote paper.
| Temperature, 0
|Relative humidity, %
|Conditioning conditions for most printed papers
|For tropical conditions
|For special conditions
The samples are kept until they reach equilibrium moisture content, which is considered achieved if, with two consecutive weighings of the sample carried out after 1 hour, the last mass differs from the previous one by no more than 0.25%.
When storing and testing samples, the equilibrium humidity should not change (GOST 13523–78. Method of conditioning samples).
Mondi offset paper | formats, prices
Mondi offset paper
– multifunctional cellulose paper with sizing and excellent surface properties for high-quality printing. It is characterized by a high degree of whiteness, opacity, uniform structure, resistance to plucking and the absence of dust separation. Excellent for various methods of printing highly artistic illustration and text publications, visual products and multi-color publications with a long service life (books, reference books, advertising and paper products). Widely used in printing houses for printing full-color book and magazine products, including multicolor publications with artistic content. This printed product contains complex halftone illustrations. It is subject to high requirements for shelf life. Offset paper is the main product the company specializes in. The share of JSC Mondi SYLPK accounts for 37% of the Russian offset paper market
JSC “Mondi Syktyvkar LPK”
Service station: 00279404-002-2009
60, 65, 70, 80, 90, 100, 120, 160, 190, 235 g/m 2
Certificate of conformity: download
Conclusion about durability:
Quality certificate: download
|characteristics of offset paper
|units of measurement
60 – 235
5 – 7
85 – 190
120 – 800
142 – 148
102 – 105
84 – 91
Longitudinal breaking length
See also: Kotlas offset paper
, Goznak offset paper
, Offset paper Kama
, Offset paper Turinsk
, Offset paper Svetogorsk
, Offset paper
US Standard Paper Weight
Determining paper density by the weight of the paper package was previously widely used in the UK, Europe, as well as in North America, where it is still used. The popularity of the method in Europe fell after the international standardization of paper sizes under ISO 216 and its national predecessors in European countries.
Weight is defined as the weight of a ream of uncut paper in pounds (lb) (Note: Reams of paper are often written # after the weight number instead of pounds). There are many types of uncut paper that are used in various industries: for office paper and cardboard, Bond, Cover and Index are used.
So if you have a sheet of 20lb Bond Letter, it will be the same thickness as 20lb Bond Legal, although the sheets will weigh differently. But a sheet of 28lb Bond Letter sized paper will not be the same size as a 28lb Cover Letter sized paper since the uncut Bond and Cover sheets are different.
The paper most commonly used in offices is 20-24 lb. Often suppliers will omit the word Bond on the packaging and simply list the weight as 20 lbs or 24 lbs, since other packaging formats always write Index or Cover unless the default Bond type has been used.
Newsprint has its own type, Newsprint, which measures 24″ x 36″ in uncut sheet size. This is significantly thicker than the untrimmed Bond and Cover types, so the most common 30lb Newsprint is actually significantly thinner than the 20lb Bond type. The next page talks about the different types of stock types of uncut sheets of paper.
Tables for converting paper weight from g/m2 to lb and vice versa.
Density grams per square meter (gsm)
Paper weight according to ISO 536 is indicated mainly on the product packaging in g/m2 or GSM. This standard defines the weight of one sheet of A0 paper (which has an area of 1m2) depending on the specific gravity. This means that an A0 sheet of 80 g/m2 paper will weigh 80 grams, an A0 sheet of 100 g/m2 paper will weigh 100 grams, and so on.
Note: the packs are usually written GSM, not g/m2 in most companies. This was due to the inability of early computer packages to display superscript characters—a feature of inventory, accounting, and billing systems.
Paper commonly used in offices typically has a weight between 70gsm and 80gsm, with 80gsm being the most commonly found weight. Some accountants and lawyers use thicker paper, ranging from 90gsm to 120gsm for formal correspondence.
See this page for a chart of individual sheet weights of 4A0, 2A0, A0, A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10 for various commonly used paper weights.
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; In this case, a distinction is made between macro and micro porosity.
Macropores, or simply pores, are spaces between fibers filled with air and moisture. Micropores, or capillaries, are tiny spaces of indeterminate shape that penetrate the top 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, lightly 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 microns. Such papers absorb paint well due to their loose structure, that is, a highly developed inner surface.
If we depict the structure of paper in the form of a scale, then at one of its ends there will be macroporous papers consisting entirely of wood pulp, for example, newspaper. The other end of the scale will accordingly be occupied by pure cellulose microporous papers, for example coated ones.
Thus, coated papers are classified as microporous, or capillary, papers. They also absorb paint well, but under the influence of capillary pressure forces. Here the porosity is only 30%, and the pore size does not exceed 0.03 microns. The remaining papers occupy an intermediate position.
In fact, this means that when printing on offset paper, both the solvents contained in the paint and the coloring pigments penetrate into the pores, as a result of which the concentration of pigment on the surface is low and it is impossible to achieve rich colors.
Macroporous papers accept paint well, absorbing it as a whole. The paints here are low viscosity. Liquid paint quickly fills large pores, absorbing to a fairly large depth, and excessive absorption can even cause the print to “punch through,” that is, the image will become visible from the back of the sheet.
The most common types of paper weights used in printing for the manufacture of various products:
40-70g/m2 – the thinnest, it can be coated or newspaper. Coated paper is used for printing large circulations of multi-page magazines and reference books, and newsprint is used for printing cheap forms and newspapers. .
80gsm is a common office paper that everyone uses to print office documents. In the Raveda printing house this paper is used for black and white printing and reproduction. It is called “80g offset paper”.
90-115gsm – Used for printing handout flyers and multi-page brochures. 90g paper at the Raveda printing house is used for printing blocks of quarterly calendars for clients who want to order quarterly calendars cheaply in Moscow
130gsm – used for printing booklets and pages when making brochures up to 40 pages.
150g/m2 – paper for thick leaflets or flyers.
170g/m2 – this paper is used when you need to print desk calendars at the lowest price in Moscow and print house calendars
200g/m2 – used for printing covers when you need to print catalogs and when you need to order paper bags cheaply in Moscow.
250 g/m2 – for printing flyers, as well as brochure covers in cases where you need to order the production of catalogs.
300 g/m2 – a type of paper for making covers in brochures and notebooks, when you need cheap production of notebooks, as well as printing business cards in Lyubertsy