Complete explanation of prepress technical cases 1

2022-06-17
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Complete solution of prepress technical cases (13)

III. ink is a kind of fluid substance with certain viscosity, which is evenly dispersed in the connecting material by pigment particles, fillers, additives, etc

1. Composition of ink

pigment is a kind of color, black or white powder material with high dispersion, which is insoluble in water and organic solvents. It plays a role in displaying color in ink. According to the source and chemical composition of pigment components, it can be divided into organic pigments and inorganic pigments: inorganic pigments are composed of non-ferrous metal oxides or some metal insoluble metal salts, and inorganic pigments can be divided into natural inorganic pigments (mineral pigments) and artificial inorganic pigments; Organic pigments refer to colored organic compounds, which can also be divided into natural and synthetic categories according to their sources. Now the commonly used organic printing inks are basically synthetic organic pigments with complete colors and better performance than inorganic pigments

printing requires high ink and pigment, especially color purity, dispersion, light resistance, transparency, etc. At ordinary times, it is required that the hue of the pigment of the color ink should be close to the spectral color, and the saturation should be as large as possible. The pigment transparency of the three primary color inks (cyan, magenta and yellow) must be high, otherwise it will greatly affect the quality of the printed matter. No matter what kind of pigment, it must have good water resistance, be able to quickly and evenly combine with the connecting material, and have good acid, alkali, alcohol and heat resistance

binder is a kind of chemical substance, commonly known as ink blending oil, which plays a role in dispersing pigments, giving ink proper viscosity, fluidity and transfer performance, and fixing pigments on the surface of printed matter through film-forming after printing. The connecting material can be made of various substances, such as dry vegetable oil, mineral oil, solvent, water and various synthetic resins. The fluidity, viscosity, neutral acid value, color intensity, water resistance and printing performance of the ink during use all depend on the binder. The same pigment can use different binder to make different types of inks; Because the same binder uses different pigments, it still produces the same type of ink. Because the binder does not have the fundamental performance to change the ink, the quality of the ink mainly depends on the binder in addition to the pigment itself

the filler is a white transparent, translucent or opaque powdery material, which plays the role of filling. Proper use of some fillers in the pigment can not only reduce the amount of pigment to reduce the cost, but also adjust the thinness and fluidity of the ink, and improve the flexibility of the ink formulation design

additives are materials added to improve the performance of the ink itself in the process of ink manufacturing or printing. When the ink composed according to the basic formula still cannot meet the use requirements in some characteristics, or cannot meet the printing requirements due to changes in conditions, a small amount of additional materials must be added to solve the problem

2. Types of inks

according to different methods, inks can also be divided into different types. Commonly used are relief printing ink, lithographic printing ink, gravure printing ink, silk hole printing ink, special functional ink, etc

relief printing ink can be divided into printing ink for books and periodicals, printing color ink (copperplate ink), printing plastic ink, rubber relief plastic ink (flexible plastic ink), relief water-based ink, relief rotary printing ink, etc. according to different characteristics. This kind of ink basically belongs to penetration drying ink. In the printing process, we should pay attention to the appearance of poor adhesion, chalking, dirt and other ills

offset printing inks include various offset printing inks, offset iron ink, offset photosensitive ink, offset thermosetting ink, etc. The ink for lithography requires high colouring power, water resistance, good fluidity and drying speed

gravure printing inks include various photographic gravure inks, engraving gravure inks, Gravure plastic film inks, etc

printing inks for silk hole printing include silk printing ink, silk plastic ink, oily transfer ink, water transfer ink, etc

in addition to the above commonly used inks, there is also an ink that can play a certain special effect, such as micro colloidal ink, gold silver ink, fluorescent ink, magnetic ink, security anti-counterfeiting ink, conductive ink, replication ink, monitoring ink, temperature indicating ink, color developing ink, edible ink, etc

3. Characteristics of ink

ink is a kind of slurry adhesive with certain fluidity. Viscosity, yield value, thixotropy, fluidity and dryness all determine the performance of ink

viscosity: it is a property that prevents the flow of fluid substances. It is a measure of the relative motion ability of the method standards such as the interaction between fluid molecules and the determination of potassium permanganate consumption in GB 31604.2, that is, the resistance of fluid flow. The viscosity of the ink is related to the transfer of the ink and the nature and structure of the paper during the printing process. If the viscosity of the ink is too large, the transfer of the ink during the printing process is not easy to be uniform, and the phenomenon of roughening the paper occurs, causing the layout to be scratched; The viscosity is too small, the ink is easy to emulsify and dirty, which affects the quality of the printed matter. The requirements for ink viscosity in the printing process depend on the printing speed of the printing machine, the degree of public software on the paper structure, the change of temperature and humidity in the surrounding environment and other factors

yield value: refers to the minimum moving stress required to make the liquid start flowing. If the yield value of the ink is too large, the fluidity will become poor and it will not be easy to open. If the yield value is too small, the printing point is easy to halo, resulting in unclear printing. The yield value is related to the structure of the ink and has a direct impact on the fluidity of the ink. It is an important test index for the quality of offset and gravure ink

thixotropy: refers to the phenomenon that the ink changes from thick to thin with the mixing action when it is stirred by external force, and returns to the original consistency when the mixing action stops. Due to the thixotropy of the ink, the ink will increase the fluidity and ductility after being rotated by the printing press on the ink roller, making the ink easy to transfer; When the ink is transferred to the paper after printing, due to the loss of external force, the ink thickens from thin to thick and does not flow around, forming a good impression. If the thixotropy of the ink is too large, the ink in the ink bucket is not easy to rotate, which will affect the ink transfer function of the ink roller

fluidity: refers to that the ink will flow like a liquid under its own gravity, which is determined by the viscosity, yield value and thixotropy of the ink, and is also closely related to the temperature. The fluidity of ink is related to whether the ink can be poured out of the container, transported from the ink storage tank to the ink bucket of the printing machine, smoothly transferred from the ink bucket, well distributed on the printing machine, transferred to the layout and transferred to the substrate, and also affects the printing effect

length of ink filament: refers to the extent that the ink is initially stretched into a filament without breaking. Its length is related to the thixotropy, yield value and plastic viscosity of the ink. Ink with short ink filaments is an ink with good printing performance in offset printing and letterpress printing. It will not cause ink flying in the printing process. At the same time, the ink layer on the printed matter is also uniform and thick. The length of ink is a common method to measure the performance of ink

ink drying: ink drying refers to the process in which the ink becomes a solid film from a liquid or paste after it is attached to the printed matter to form an imprint. This process is completed by the transformation of the edge material in the ink from a liquid or paste to a solid. Because the binder used in various inks and its formula proportion are different, the drying process of inks is also different. After the ink is transferred from the printing plate to the printing surface, a part of the connecting material in the ink penetrates, and the solvent in the connecting material also begins to volatilize. Some connecting materials begin to produce chemical or physical reactions, so that the imprinted ink layer on the surface of the substrate gradually increases its viscosity and hardness, and finally forms a solid film layer. Generally, relief printing inks are mainly permeable drying, offset printing inks are mainly oxidized conjunctiva drying, and intaglio printing inks are mainly volatile drying because they use highly volatile solvent as connecting material

prepress printing common sense and demonstration price

1 Unit of paper:

a. gram: weight of one square meter (length × Width ÷ 2) =g is the weight

b. order: 500 sheets of paper unit weight: order (ex factory specification)

c. ton: the same as the normal unit, 1 ton =1000 kg, used to calculate the paper price

2. Paper specification and name:

a. there are four most common paper specifications:

(1) Positive paper: 109.2 cm long Width 78.7 cm

(2) Large size paper: 119.4 cm long Width 88.9 cm

(3) Self adhesive: 765cm long Width 535 cm

(4) Carbonless paper: there are positive and generous specifications, but there is paper loading Medium paper The paper price is different according to the paper (see the classification of paper price)

b. the most common name of paper:

(1) Copy paper: 17g positive specification: used for value-added tax tickets, gift inner packaging, generally pure white

(2). Typing paper: 28g positive specification: used for joint sheet The table has seven colors: white Red Yellow LAN Green Pale green Purple

(3). Glossy paper: G positivity specification: glossy on one side, used for copy Table Notes, low-grade printing paper

(4). Writing paper: G size It is used for low-grade printing, most of which is domestic paper

(5) Double offset paper: G large Both positive and negative, used for medium - grade printed matter and domestic products Joint ventures and imports are common

(6). Paper: G roller paper Positive paper Newspaper selection

(7). Carbon free paper: G size Positive degree is available, with direct copying function, and points are available Medium Lower paper,

upper, middle and lower paper can not be exchanged or reused. The paper price is different. There are seven colors, which are commonly used for joint order The oil delivery valve of the electronic universal testing machine is a shunt flow regulating valve table

(8). Coated paper:

a. positive degree of double copper G It is used for high-grade printing

b. single copper: used for carton Cartons Tote Bag. Medicine box, etc High grade printing

(9). Matte paper: G for elegant appearance High grade color printing

(10). Gray background white paper: more than 200g, with white background gray, used for packaging

(11). White cardboard: 200g, double-sided white, used for medium-grade packaging

(12). Kraft paper: G, used for packaging Cartons file pocket. File bag. Envelope

(13). Special paper: usually imported paper, mainly used for cover ornament. Arts and Crafts. Fine printing

3. Quotation formula and skills:

(1) Carefully observe the strength of customers and their printed samples

(2). Carefully measure the sample specification, paper and various post printing Prepress process

(3). Use a calculator to calculate costs and profits in detail

(4). The quotation adopts puns. The price is not high (not higher than the psychological price of the customer) and the price is not low (lower than the price of the same trade)

(5) Bargaining refers to negotiating with customers on the reasons and grounds for bidding

for example, paper size, paper quality, domestic and imported films, printing quality, delivery time, and what kind of machine is used for printing Good conditions for the other party to accept your offer

(6). Demeanor: sophisticated Generous Honesty Feeling

(7) Friendly language: be polite Be civilized Laugh before you speak Neither humble nor overbearing

4. Proofreading andTips for purchasing rangefinder
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