Printing processing considerations

Die-cut production

Usually in the making of the manuscript, the packaged die-cuts are made into the same file so that the inspection can be performed intuitively. In this case, a layer should be set up specifically for the die-cut. Monochrome film to facilitate the production of die-cutting tools. The method of drawing a die-cut version is basically the same as the drawing method of a paper packaging structure diagram.

"bleeding" setting

In the manuscript draft, when the background or picture of the package reaches the border, the edge lines of the color block and the picture should be extended to about 3mm beyond the cutting line, so as to prevent the printed product from appearing white due to errors in the cutting process. Edge, affect the appearance. The edge line outside the patch that extends beyond the cutting line is called the "bleeding line."

Resolution

In computer-aided design, there are two main methods for drawing illustrations. One is vector graphics. If you use 11lustrator, Freehand, or Coreldrow software, you can enlarge the image many times without affecting the total clarity of the tiger. The use of scanning or electrical points of the pictures and illustrations, through the use of Photoshop, Painter and other graphics processing software to create a bitmap image, the bitmap is composed of a pixel, can not be arbitrarily zoomed like a vector. Therefore, it is very important to deal with the relationship between image size and resolution. The output resolution is represented by the number of pixels in the length unit. The resolution setting should be based on the specific design needs. In general, objects that are viewed within 2 meters of a person's eyes, such as albums and packaging, require at least a resolution of 300 dpi or more in order to exhibit a fine, soft continuous tone. Therefore, when processing the image of the packaging design, reasonable output resolution should not be provided in order to achieve a beautiful printing effect.

Color output mode

For monochrome prints, the output of a monochrome film can be, but the color printing is done by color separation, the output of magenta, yellow, blue, black four-color film for plate making, so in the image design software, the image should be set to The CMYK four-color mode, which matches the four-color printing, can obtain the desired four-color separation sheet.

Spot color settings

In order to achieve the aim of pursuing the color saturation and brightening effect of the main colors, many packagings are provided with special color printing plates. For special edition inks, special color separations must be output. The output film usually does not reflect the color, should be attached with an accurate color code, in order to use as a proof and printing process.

Register line settings

Also known as the "color registration line," when a design draft requires two or more colors for printing, a register line is required. The registration lines are usually arranged at the four corners outside the layout and are cross-shaped or T-shaped for the purpose of accurate overprinting during printing. Therefore, in order to achieve accurate overprinting, each plate, including the die-cut version, must accurately register lines. Registers are superimposed together to ensure that the packaging is printed accurately.

Bar code making and printing

The barcoding of products has greatly improved the efficiency of the logistics links such as delivery, purchase, inventory and sales of goods. Barcodes must be correctly read by the scanner and require high standards for platemaking and printing. Bar code plate printing and printing should pay attention to the following issues.

(1) Bar code printing size in platemaking When the packaging area size allows, the bar code standard size should be 37.29mm X 26.26mm, and the scaling ratio should be 0.8-2.0 times.

(2) The height of bar code symbol shall not be arbitrarily shortened. For some special cases where the product packaging area is small, the height of bar code symbol may be appropriately truncated, but the remaining height shall not be lower than 2/3 of the original height.

(3) The font of the character with bar code shall be in the shape of the character set printing image in the national standard GBl2508, and the printing position shall be placed in accordance with the provisions of the national standard GBTl4257-1993 "Location of general product bar code symbol".

(4) The background color when printing is usually white or light, the lines are black or dark, and the contrast density between the background and the lines is greater than 0.5. The lower the reflectivity of the bar code, the better, and the higher the reflectivity of the blank, the better.

(5) Note the printability of the bar code.

(6) It is required that the direction of the paper fibers of the bar code be consistent with the direction of the bar code so as to reduce the variation of the bar and space.

Deinking: The decisive factor is the type of ink impurities in waste paper
Current deinking technology removes most of the impurities and inks. However, with the continuous development of new printing technologies and the increasing complexity of ink formulations, the complete removal of ink has become a major challenge. The deinking operation largely depends on the type of ink and impurities in the waste paper.

First, the composition and characteristics of printing ink

1. The composition of the ink depends on the type of paper to be printed, the printing method, the drying process, and the purpose of the paper.

There are two main components:

1 Pigment or Dyes: The pigment provides color and opacity to form a certain contrast with the sheet of paper it is intended to use. It is also important for the viscosity transfer and the required flow characteristics.

2 Carrier (Binder): The binder imparts the necessary transfer properties to the ink, and has the function of spreading and carrying ink particles. It is the carrier of the pigment particles and is advantageous for the retention of pigments or dyes on paper sheets. The binders usually have dry vegetable oils, mineral oils, synthetic or natural resins, plastics and organic solvents.

3 Others: Printing inks may also include some other components such as adhesives, solvents, drying agents, wetting agents, and paraffin waxes.

2. Printing ink must meet certain requirements

It should be able

1 provides good contrast;

2 has good printability for the printing method adopted;

3 has good drying characteristics;

4 The stability is good.

Important ink properties are viscosity, tackiness, size, and drying characteristics. The viscosity of the ink determines the flow properties of the ink and how the ink yields under plate pressure. The fluidity of the ink also affects the penetration of the ink. Viscosity refers to the action of the ink against external forces, such as the tension of the printing plate, so that it does not fall off from the surface of the sheet. The ink must have a certain viscosity in order to adhere well to the paper sheet. However, if the viscosity is too high, the surface of the paper sheet may be torn or fluffed, and the powder may fall off. The size is used to measure the dispersion of the ink particles on the paper sheet. The short and coarse ink particles will cause spots and the ink layer will wrinkle: The long stick ink particles will cause ink drawing, which is a special problem in newsprint production. . In addition, the fixing properties of the ink are particularly important because further processing after printing must be performed after the ink is fixed.

All of these ink properties are directly related to the removal efficiency of the ink. They determine the tightness of the bond between the ink and the fiber and the ease of release.

3. Ink fixation

The fixation of the ink on the paper sheet is based on one of two main mechanisms:

1 The binder is adsorbed on the pores of the sheet;

2 The ink cures on the surface of the sheet.

Second, modern printing technology

With the continuous development of printing technology in recent years, a variety of new printing processes have emerged, such as flexographic printing, laser printing, xerography and inkjet printing, and corresponding special ink formulations. An obvious requirement for printing ink is to be able to adapt to the required printing method. Naturally, the formulation of a particular ink is adapted to the type of printing it is intended to use. Before we discuss how to remove these new inks, let us take a look at the printing methods they apply.

1. Newsprint/magazine paper printing process

1 Toppan Printing: Toppan printing is mainly used for newsprint, magazines and cowhide bags. The embossed ink has a moderate viscosity and viscosity, and it is in a paste form. It consists of a pigment and a desiccant mixed in a dry oil binder. Dispersion of carbon black in oil (hydrocarbons) is a typical formulation for letterpress inks. Resins and other adjuvants are sometimes added to achieve special properties such as gloss. The ink can be dried by penetration, volatilization, or gel fixation. Most sheet-fed embossed inks are anchored by oxidized conjunctiva.

2Plain printing: Printing is based on the principle of oil-water immiscibility to make the text part inking, non-graphical part of the indirect printing method does not ink. The offset ink is composed of water-insoluble or solvent-resistant water-resistant binders and pigments. Compared with the embossed inks, the pigments used in the plain inks have strong coloring power and often use flax oil as a binder. In modern ink formulations, alkyd resins and dry oils are used as the binder. Polymerization occurs when dried, resulting in a strong cross-linked film. Thermosetting inks are commonly used as a binder for hydrocarbon-based resins and are dried by evaporation. UV light-curable inks are composed of acrylic monomers and their prepolymers. They are polymerized under UV light to form a strong film, which is commonly used in newsprint color printing.

3 Gravure printing: Rotary rotogravure printing is the use of the graphic part of the concave section of the plate to form the graphic, the blank part is higher than the graphic part. Intaglio printing ink is a kind of quick-drying ink. The main mechanism of drying is: relying on the volatilization of the ink solvent, drying is usually achieved under heating conditions. These inks have low viscosity and are easily transferred from the concave portion of the printing plate to the paper under the effect of capillaries in the sheet. This type of ink is typically a polyamide or polyacrylamide dissolved in an aromatic or ester solvent as a varnish. Because this type of ink has a fire, or even the risk of explosion, some inks use water-based inks with low alcohol content, water and alcohol as the connecting material.

4 Flexographic Printing Inks: Flexographic printing is improved from letterpress printing. In relief printing, some of the ink spills from the side of the high pressure zone. Because not all inks are instantly absorbed by the sheet, it is more important that the hardness of the metal or plastic plate will cause permanent deformation of the surface structure of the sheet. These quality defects promote the development of the flexographic printing plate. The new printing plate is called aniline letterpress. Often used for low-cost packaging paper and paperback printing, this technology is now more and more widely used for newsprint printing.

Similar to gravure inks, flexible inks have two distinct properties, low viscosity, and fast drying. Commonly used alcohol and ester mixed solvents are used as connecting materials and rely on volatile drying.

Reproduced from: 55jx.com