Ink is made byChromophore(such as pigmentdyestuffEtc.), binding material, filling (filling) material, additional material, etcHomogeneous mixture；It can be printed and can bePrintedUpper drying;yesColoredSlurry adhesive with certain fluidity.Therefore, color (hue), body (rheological properties such as thinness and fluidity) and drying performance are the three most important properties of ink.There are many kinds of them,physical propertyAlso different, some are very thick and sticky;Some are quite rare.Some takevegetable oilAs binding material;Some use resin, solvent or water as binding material.These are based on the object of printing, namelySubstrate, printing methodPrinting plateType and drying method.
Ink is a substance used to form graphic information in the printing process. Therefore, ink plays a very important role in printing. It directly determines theStep tone, ColordefinitionEtc.In printing, we need to understand the composition and classification of ink.
The ink shall have bright color, good printing adaptability and suitable drying speed.In addition, it should also have certain application indicators of resistance to solvent, acid, alkali, water, light, heat, etc.As printing, paper and other requirements become higher and highertechnical conditionsAlso improved.Such as modern high-speed multi-color printing press and color wheelPrinting machineThe ink is required to dry at a speed of several seconds or even faster.Glass card, gold and silver cardart paperBright ink is required.Print plastic film, which shall be well combined with plastic film;Or the ink that is adhered to the plastic film to the maximum extent.It is required to use photosensitive ink to print special printing materials.
Ink is mainly used forPrinting industry。Pigments and binders are the two main raw materials of inks.
Printing ink
printingjockeyWhen selecting ink, color is generally regarded as the first requirement. Ink color (hue) is one of the most intuitive indicators. In fact, it is a major indicator reflecting the quality of printing to a large extent.Therefore, the quality of pigment plays a decisive role in the quality of ink.Pigment is a solid powdery substance with a certain color that is insoluble in water, oil or binder.It is not only the main solid component of ink, but also the visible color body part printed on any object.To a large extent, it determines the quality of ink, such as color (hue), thinness, etc.It has great influence on viscosity, physical and chemical properties, printing performance, etc.Therefore, it is required that the pigments have bright colors, high concentrations, goodDispersityAnd other relevant properties required by the ink.
In fact, perfect ideal pigments do not exist and can only be satisfied relatively or partially.
Binder is a sticky fluid.As the name suggests, it plays a connecting role.In the ink industry, it is to mix and connect powdery pigments and other substances, so that they may form a slurry with a certain fluidity after grinding and dispersingAdhesiveBody.
Binder is the fluid component of ink.The fluidity (property), viscosity (property), dryness, and printing performance of the ink all depend on the binder.Therefore, binders are the basis of ink quality.All kinds of vegetable oils can be used to make ink binding materials.someAnimal oil、mineral oilIt is also used in ink binders.Solvents and water are no exception.
In recent decades, the emergence of various resins has expanded the source and variety of binders.Filling (filling) material is white, transparent, translucent or transparent powdery material, which is also a solid part of ink.Mainly fromFilling actionOf.In ink, it is the pigment filling part.Proper use of some fillers can not only reduce the amount of pigment used, reduce costs, but also adjust the properties of ink, such as thinness, fluidity, etc.It also improves the flexibility of formula design.
Additional materials.It is not difficult to understand that additive is an additional part of ink in addition to its main components.They may be additional parts of pigments, binders, or finished inks, depending on the characteristics and requirements of the product.
Of course, many additional materials are also printing (auxiliary) auxiliaries.
There are about 5000 kinds of raw materials used to manufacture ink in the world.
Ink composition
Announce
edit
The main components of the ink are as follows:
Printing ink
Pigment is the solid component of ink, which is the color developing substance of ink, and is generally insoluble in water.Ink colorsaturation、Colouring force, transparency and other properties are closely related to the performance of pigments.
Binder is the liquid component of ink, and pigment is the carrier.stayPrinting processThe binder carries pigment particles from the ink half of the printing pressink roller、Printing plate, transferred toSubstrateAn ink film is formed on the substrate, and is fixed, dried and adhered to the substrate.Gloss, drynessmechanical strengthThe properties are related to the properties of binders.
The additives added to the ink are to improve thePrintability, such as viscosity, adhesiveness, dryness, etc.
along withPrinting technologyWith the development of, the variety of ink is increasing, and there are many classification methods.If according toPrinting modeThere are five categories:
relief printingInk: books and periodicalsBlack ink, rotating black ink, colorLetterpress inkEtc;
The ink configuration process is relatively complex. Generally, pigments, binders and various additives are mixed in a certain proportion in the ink blender to form oilPaste, and thenRoller grinderOr it is made by repeatedly grinding to make the pigment disperse evenly in the binder with fine particles.
Classification of inks
Announce
edit
Printing ink
With the development of printing technology, the variety of ink is increasing, and there are many classification methods.If classified according to the printing method, there are five kinds of letterpress printing ink: black ink for books and periodicals, rotary black ink, color letterpress ink, etc;
Special printing ink: foaming ink, magnetic ink, fluorescent ink, conductive ink, etc.
Printing suitability of ink
The performance of substrate, printing ink and other materials that match the printing conditions and are suitable for printing operations is called printability.
The printability of the ink refers to the performance that the ink matches the printing conditions and is suitable for printing operations.It mainly includes viscosity, adhesionThixotropy, dryness, etc.
Ink viscosity can be usedViscometerThe commonly used viscometers are parallel plate viscometers,Rotary viscometer, Lalay viscometer, etc.
The faster the speed of the printing machine, the greater the fluidity of the ink and the smaller the viscosity.
The viscosity of ink can be usedInking oilOr inkdiluentMake adjustments.
2. Adhesion of ink
Printing ink
Ink fromInk fountaintowardsink roller, printing plate（Blanket）When the substrate surface is transferred, the ink film first splits and then transfers. The ability of the ink film to prevent the ink film from breaking in this dynamic process is called the adhesion of the ink.The physical quantity that measures the adhesiveness of the ink is called the Tack value of the ink.
Ink Tack value can be measured with ink adhesion tester.
In the process of printing, if the adhesion of the ink does not match the performance of the substrate and the printing conditions, the paper will lose powder, hairink trapping BadPrinted editionDirt, etcprinting trouble。
The adhesion of ink can be adjusted with adhesive remover or ZY ink additive.
3. Thixotropy of ink
At a certain temperature, after the ink is stirred or applied with external mechanical force, the fluidity is improved and the viscosity is reduced;Stand stillAfter that, the fluidity becomes bad and the viscosity rises. This property is called the thixotropy of ink.
During printing, if the inkThixotropyIf it is not good, printing failures such as "poor inking", uneven ink transmission, and severe dot enlargement will occur.In order to prevent the above failures, it is necessary to use an ink shovel to frequently stir the ink in the ink bucket or install ink in the ink bucketAgitatorThe ink is blocked from time to time.
4. Drying of ink
The drying of ink is more complex, mainly in the following three forms.
Osmotic drying。Some of the binders in the ink penetrate into the substrate, and the other part is fixed with the pigment on the substrate surface for drying.high speedWeb printing machineThe non thermosetting rotary ink used is mainly osmotic dryingPrinted newspapers, periodicals.
Oxidative polymerizationdry.The binder in the ink and oxygen in the air occurpolymerizationFilm forming and drying on the substrate surface.Offset bright resin ink, bright color, good gloss, mainly oxidation polymerization drying, used for printing high-grade fine offset products.
Volatilization drying.Some binders in the ink evaporate into the air, and the remaining binders and pigments are fixed on the substrate surface and dry.Gravure printing ink uses volatile solvent as binder, and the binder used is benzenexylene。At the beginning of the 20th century, water basedWater-based ink, forGravure printingandFlexographic printingIt reduces the pollution to the environment and has a bright future.Volatile and dry ink is particularly suitable for printingAbsorptivityOfFilm material, such asplastic film、Metal foilEtc.
The drying of many inks is often a combination of two drying forms to complete the ink film drying.For example, quick fixing of sheet paperOffset printing inkIt is suitable for printing general offset printing products. It is dried by combining infiltration and oxidative polymerization.
During printing, if the ink dries poorly, the back of the sheet will be causedset-off Printing faults such as page sticking, ink film tarnishing, ink "crystallization", etc.
In order to speed up the drying of ink, you can addDesiccant。The commonly used driers are: cobalt dry oil, manganese dry oil, lead dry oil, etc.In order to reduce the drying speed of the ink, drying can be added to the inkinhibitor。
component
Announce
edit
Printing ink
Pigment is insoluble in water andOrganic solventHigh in color, black, or whiteDispersityIt is a kind of powder material that plays the role of displaying color in ink.According to the source and chemical composition of pigment components, it can be divided intoOrganic pigmentandInorganic pigmentTwo categories: inorganic pigments are made of nonferrous metalsoxideOr some metal insolubleMetal saltComposition, inorganic pigments can also be divided into natural inorganic pigments（Mineral pigment）And artificial inorganic pigments;Organic pigment refers to coloredOrganic compoundIt can also be divided into natural and synthetic categories according to its source.The commonly used organic printing inks are basicallySynthetic organic pigmentThe color is complete and the performance is better than that of inorganic pigments.During printing, there is a high requirement for ink and pigment, especially for color purity, dispersionLightfastnessTransparency.At ordinary times, it is required that the hue of the pigment of color ink should be close to the spectral color, and the saturation should be as large as possible,TricolorInk (greenMagenta, yellow) must have high transparency, otherwise the quality of printed matter will be greatly affected.No matter what kind of pigment, there must be goodWater resistance, can quickly and evenlyJoining materialIt has good acid resistance, alkali resistance, alcohol resistance, heat resistance and other properties.
Binder is a kind of chemistry that disperses pigment, gives ink proper viscosity, fluidity and transfer performance, and fixes pigment on the surface of printed matter through film formation after printingmaterial, commonly known as inking oil.Connecting material can be made of various substances, such as dryvegetable oil、mineral oil, solvents and water, and varioussynthetic resinEtc.Liquidity, viscosity and neutrality of ink in useacid value, color and lustreWater resistanceThe performance of the printed matter depends on the binder. The same pigment can use different binders to make different types of inks;Because the same binder uses different pigments, it is still made of the same type of ink. Because the binder does not have the ability to change the fundamental performance of the ink, the quality of the ink depends on the binder in addition to the pigment itself.
The filler is white, transparent, translucent orOpaqueOfPowdery substance, plays the role of filling.Proper use of some fillers in the pigment can reduce the amount of pigment tocost reduction, and can adjust the ink thinningConsistency, liquidity, can also improve inkFormulation designThe flexibility of time.
Additives are some materials added in order to improve the performance of ink itself in ink manufacturing or printing use.When the ink composed according to the basic formula still cannot meet the requirements of use in some aspects of characteristics, or cannot meet the requirements of printing use due to the change of conditions, a small amount of additives must be added to solve the problem.
characteristic
Announce
edit
performance
Ink is a kind of paste adhesive with certain fluidityYield value, thixotropy, fluidity, dryness and so on all decide the ink performance.
Viscosity:It is a property that prevents the flow of fluid substances. It is a fluidIntermolecular interactionTo prevent the intermolecular relativityAthletic abilityA measure of resistance to fluid flow.The viscosity of ink has an important relationship with the transfer of ink in the printing process, the nature and structure of paper. The viscosity of ink is too large, the transfer of ink in the printing process is not easy to be uniform, andPaper rougheningThe phenomenon of, make the layout;The viscosity is too small, and the ink is easy to emulsifyDirtying, affecting the quality of printed matter.The requirements for ink viscosity during printing depend on thePrinting speed, the degree of public software on the paper structuresurrounding environmentThe change of temperature and humidity.
Yield value:It refers to the minimum moving stress required to make the liquid flow.If the yield value of ink is too high, the fluidity willVariogramIt is not easy to open, the yield value is too small, and the dot is easy to become dizzy when printing, which causes the printed matter unclear.The yield value is related to the structure of the ink and has a direct impact on the fluidity of the inkGravure printingImportance of Ink QualityTest index。Generally speaking, the particle size and quantity of pigment in ink increase, and the force and viscosity that hinder liquid flow will also increase.For example, letterpress andLithographyThe ink contains a lot of pigments, and the force must be greater than a certain value to flow.Therefore, the force on the ink must be greater than a certain value to flow, which is the yield value of the ink.
Thixotropy:It refers to the phenomenon that when the ink is stirred by external force, it changes from thick to thin with the stirring action, and then returns to the original consistency when the stirring action stops.Due to the thixotropy of the ink, the ink is subject toPrinting machineAfter the rotation of, it will increase the fluidityDuctility, 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 becomes thinner and thicker without flowing around, forming a good impression.If the thixotropy of the ink is too large, the ink in the ink bucket will not rotate easily, which will affect the ink transfer function of the ink roller.
Printing ink
mobility:It means 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 temperature.The fluidity of ink is related to whether the ink can be poured out of the container, transferred from the ink storage tank to the ink bucket of the printing machine, transferred smoothly from the ink bucketPrinting machineGood distribution, transfer to the layout and transfer to the substrate also affect the printing effect.
Ink length:It refers to the extent to which the ink is initially drawn into filaments without breaking. Its length depends on the thixotropy, yield value andPlastic viscosityofInk with short ink threadOffset printingIn letterpress printing, the ink with good printing performance will not cause the phenomenon of flying ink in the printing process. At the same time, the ink layer on the printed matter is also uniform and thick.The length of ink filament is a common method to measure the quality of ink.
Drying of ink:The drying of ink refers to that the ink changes from liquid or paste to solid after it attaches to the printed matter to form an impressionPellicleThis process is completed by the transition of the edge material in the ink from liquid or paste to solid.Because the connecting material and formula proportion used by various inks are differentdrying processNot the same.After the ink is transferred from the printing plate to the surface of the printed matter, a part of the linker in the ink penetrates, and the solvent in the linker begins to volatilize. Some linkers begin to producechemical reactionorPhysical reactionSo that the printing ink layer on the substrate surface gradually increases its viscosity and hardness, and finally forms a solidfilm 。Usually letterpress printing ink is used toPermeabilityMainly dry,LithographyOffset printing inkair drying Mainly,gravureUsing inkvolatilityStrongerSolution agentIt is a binder, so it is mainly volatile drying.
difference
Difference between table and interior printing ink
Ink is an indispensable material for commodity decoration and packaging.Through printing, the packaging surface becomes beautiful, colorful, exquisite and attractive.In recent years, with theprinting businessWith the rapid development of, packaging and printing of various plastics and paper industries continue to improveProduct packagingThe level is becoming higher and higher.Composite flexible packagingPrinting andGeneral packagingThere are some differences between the two printing methods, that is, the former is interior printing, and the latter is surface printing. The inks used by both are called interior printing ink and surface printing ink. We must analyze the differences between the two inks before printing, and it is of great significance to use them correctly.Most inks in China are composed of 20%~40% binders, 5%~15% pigments, 40%~60% organic solvents and 0%~5% additives.Binder is a cohesive resin and a key component of the ink. It binds the pigment and the printed material together to play an adhesive role and make the ink shiny.Pigment determines the kind of color.Solvents dissolve resins, adjust viscosity, adjust drying speed, and improve theWetting action。Additives can improve viscosityWeatherabilityIt can resist aging and increase luster.The following is a brief analysis of the differences between interior printing ink and surface printing ink summarized by our factory over the years.
Difference of binder
surfacestamp-pad inkInk binders are mainlyPolyamide resin, whichadhesionGood, good gloss, but at high temperaturenot suited to, when compoundingfastnessPoor, the binders of non cooking printing ink are mainlyChlorinated polypropylene, also useful abroadnitric acidFiber andvinyl chloride———vinyl acetate Copolymer resin.The domestic Jinlong GD-1 and Dongfang 200 belong to this category.High temperature cooking resistant printing oil binder ispolyurethane, add a certain amount when usingHardener, mixed with two liquids and cross-linked by reaction, such as Dongfang 300.
Differences in solvents used
The solvents used for surface printing ink are mainlyxylene，Isopropanol。But the general inner sealInk solventMainly toluene and ethyl acetate.High temperature resistant cooking inner sealprinting inkIt is ethanoneEthyl acetateEtc.Interior printing ink solvent is suitable for high-speed printing and solventVolatilityFasterSolvent residueVery few.
As polyamide resin has good softness and greater elasticity, the additives added can improve its abrasion resistance and make it more firm in contact with external objects.Interior sealInk resinChlorinated polypropylene resinThe rigidity is particularly good, and the wear resistance is poor. Due to the inner printing, the requirements for wear resistance are correspondingly low.
Difference between different excipients
Due to different connection between surface printing ink and interior printing ink, their auxiliary materials, additives and additives are also differentwater lossApple，kiwifruitFruit acid ester is used to improve adhesion, gloss and viscosity.Interior printing ink is also added with variousPigment dispersant、Enhancer、DefoamerAnd other additives.
The interior printing plate making process is the same as the general plate making process, but the image on the plate isInverted image, after printingPositive imageThe image and text of the inner printing plate are positive, and they are negative after printing.Slow printing speed of surface printing ink, and printing speed of interior printing inkSpeed ratioThe surface printing speed is fast.Printing colorThe order is also different.
How to get rid of the pollution from ink
As the solvent in the ink volatilizes, pigments, resins and additives are mainly left in the printed matterDrug packagingShould not be mixed with fooddirect contact 。The grease, alcohol and ester in food (wine and spice) may dissolve the resin in ink.Then the food may be contaminated by resin and pigment.In particular, solvent based, water-based and other volatile drying inks are more likely to be resoluble.UV ink may be better because it isPhotocuringDifferent from the drying of oxidized conjunctiva of offset printing ink, it is less likely to be re dissolved after drying.
When people read books and newspapers, they should avoid the bad habit of dipping their fingers into saliva from their tongues to avoid bringing ink into their mouths.
application
Composition and Application of Gold and Silver Printing Ink
The pigment in gold ink is gold powder, which is actually made of copperkirsiteThe content of zinc in the gold powder is generally about 8%~30%. The gold ink with a zinc content of 8%~12% tends to be red, which is customarily called red gold, while the gold ink with a zinc content of 20%~30% tends to be blue, which is generally calledGreen gold, between red gold and green gold is called green red gold.In intaglio printing, 800 mesh gold powder is generally used to prepare gold ink, and the surface of gold powder particles is mostly coated withsurface active agent It can be well combined with resin binder.Silver powder is actually aluminum powder, which is composed of 65%Flaky aluminium powderAnd 35% volatilityHydrocarbonSolvent like composition.Aluminum powder pigment has small specific gravity and is easy to float in liquid.In gravure silver ink, floating silver powder with floating ability in the binder is used.Generally, 400~1000 mesh silver powder is used for silver ink. If silver ink is printed on a large area, a lower size can be usedMesh numberSilver powder of.For example, 400orderOfSilver powderTo modulate silver ink, which has highMetallic luster。
2. Binder
The binder used in gold and silver ink is a special inking oil, which is generally called gold or silver oil. The main components are oil, resin and organic solventAuxiliary materials。
The binding material of offset printing ink shall meet the following conditions:
① It must have enough viscosity to combine well with gold powder or silver powder;
② The transparency must be high and cannot affect the color of gold and silver ink;
③ The acidity of gold or silver adjusting oil should be low, otherwise it will cause chemical reaction of gold or silver powder;
④ The gold or silver transfer oil should also have fast drying and fast fixation properties to prevent the back of gold or silver ink printsMucilage。
3. Additives
Adding a small amount of bright paste or transparent yellow to the metal can enhance theInk affinityandTransitivity；In winter, adding a small amount of red dry oil to the gold ink can speed up the drying speed;InkingJoin atStearamideSurfactant can make gold powder fully wet, disperse and float in binder.reduceprinting inkDuring transferPaste versionInk piling.Adding a small amount of gloss paste to the gold ink can improve theLuminanceAnd viscosity, reduce the accumulation of gold and ink, improve liquidity.
Spot ink
Announce
edit
ISpot colorThe color of ink is more accurate.stayTintingIn theory, the use of three primary colors plus black, through the way of overprint can be deployed to any color, and finally presents a different color color.However, there are many factors that affect the final color of printed matter, such as:Ink balance, overprint effect, overprint precision, operator's skill, etc.And coloraccuracy, brightness, ink color, etc. Many spot colors are difficult to achieve through overprint, soSpot inkTo deploy.
2、 Consider cost and post process.If theBackground colorIf the same color is used, other large-area spot colors will be used in the post production processSpot color printingIn this way, one process will be omitted in the printing process, thus reducing the printing cost.
3、 Customer needs.along withcustomer demandWith the continuous diversification and personalization of, many customers will requireprinting plantUse the designated spot color for design and production to achieve the desired effect.The most common are enterprise logos, personalized business cards, high-end packaging, etc.
What are the basic requirements for spot color blending ink?Since ink is used to prepare spot colors, we are in the process of color phase preparation and printingApplicability, quantity, etc., as long as these requirements are met, the best effect and cost saving can be achieved.
Common solvent inks generally containAromatic hydrocarbonsolvent（toluene、xylene）。Some international ink companies were the first to launch non aromatic solvent inks in the Chinese market, using alcohol, ester, ether, ketone and gasoline as solvents, eliminating the possible harm caused by aromatic solvents.Solvent based inks previously used for flexographic printing are basically aromatic free, butVolatile organic solventThere are still many, which will mainly affect the printing workshopair quality。There are few residual odors in the printed matter. There may be a small amount of odor in the composite printed matter, but it is almost impossible to find it in the surface printed matter.
Water-based ink
Compared with solvent based ink, water-based ink is more environmentally friendly.It not only contains no aromatic solvents, but alsoVOCIt has also been greatly reduced, but still can not achieve zero content. It still contains a small amount of alcohol, ether, and even organic amines.It's rightenvironmental effectSmall, mainly due to air pollution in the workshop.
UV ink
UV offset printing inkExcludingVolatile organic compoundsFrom this point of view, it has taken a big step forward and is safer than water-based ink.However, its drying is achieved through ultraviolet radiation.UV inducedSkin cancerIt is possible to change oxygen into ozone, soTheThe drying device of the printing machine is equipped with an exhaust device to discharge ozone outdoors.Like water-based ink, water-based UV ink has a small amount of volatile organic solvents. Compared with ordinary UV offset ink, its environmental protection performance is worse.
In fact, the definition of environment-friendly ink is relative, but for offset printing ink with the largest usage, environment-friendly ink has a great impact onenvironmental protectionOur contribution has never stopped.
