Prohlášení o ochraně osobních údajů: Vaše soukromí je pro nás velmi důležité. Naše společnost slibuje, že vaše osobní údaje nezveřejní žádné zhoršení bez vašich explicitních povolení.
At the packaging various folding cartons and cartons that were processed with different liners and cardboards were exhibited to meet a wider range of printing needs. The successful printing method is to transfer the ink to printing materials in a controlled manner. The printed contents are text, solid and halftone images. In order to obtain a stable printing effect during the printing process, it is important to determine and control the properties of the paper that affect the relationship between the ink, the printing process, and the substrate.
First of all we have to distinguish between the main differences in print performance between paper and cardboard. The paper's easy-to-feed property plays an important role in the successful completion of the printing or finishing process. The main factors affecting the paper feeding include paper flatness, tear strength, hardness, ink absorption, dimensional stability, surface strength, tension and thickness.
Printability is a property of whether paper can stably reproduce images. It includes color density, flatness of the field output, hue range, hue, and ink transfer performance. In order to achieve better printability and paper-sheeting and corrugated paperboard transportability, it is necessary to understand the relevant paper properties.
■ Surface properties Print quality is affected by the surface characteristics of paper, liner, and paperboard, such as its optical appearance, ink absorbency, paper permeability, structure, and thickness. The surface properties of the backing material or paperboard are closely related to many factors, including the natural characteristics of the fibers used, the processing methods in the production process, the form of composition, the coating or post-processing procedures, and the like. One of the most important factors affecting print quality is the surface structure of the paper, which usually refers to the smoothness or roughness of the surface.
The smoothness of the paper is mainly controlled by the morphology of the fibers. Finishing, coating, or polishing can be used to obtain a specific surface structure. These factors also affect the paper's absorbency and permeability, as well as the final ink adhesion.
The thickness of paper varies with the way paper equipment and raw materials are processed. The thickness is directly affected by the moisture content, the pressure on the wet end, and the degree of polishing. Having a uniform thickness in the roll direction is an important guarantee for a stable printing effect. Variations in the thickness of the paper will lead to problems such as uneven output and overspreading of dots during the printing process.
The loose density of the paper determines the ratio of air and solid components in the paper. This relationship is very important for determining what kind of paper or liner material to use.
Compressibility refers to the degree to which the thickness of the paper decreases when the surface of the paper is subjected to a certain amount of pressure vertically. Compressibility essentially refers to the strength properties that affect the transfer of ink. Compressibility is affected by factors such as hardness, density, and composition.
■ Absorptive Absorption refers to the proportion of liquid (ink) entering the paper by capillary action. It is determined by the loose density of the paper. The structure of the paper presents many tiny channels and pores, and the capillary action depends on the relationship between the surface energy of the paper and the surface tension and viscosity of the ink.
The looser paper surface is relatively open, with many large pores that can absorb ink pigments and binders. Highly matte paper may absorb only the binder. The degree of absorption of the ink in the liner or paperboard is very important and it is actually a comparison of the information transmitted between the ink and the paper. If the pigment is absorbed only on the surface of the printing material, the ink can effectively absorb light. The more ink in the liner (corrugated), the more image loss will occur. Printing inks lose their luster once they are absorbed, and sometimes even show different colors. Black loses its brightness and sometimes even appears gray. The same type of ink is printed on the surface of a coated, less absorbent material that exhibits different colors. Therefore, the ability of paper to hold ink is of great significance.
The ink absorption capacity is also expressed in terms of density. Absorption rate mainly depends on the composition of the material, filler composition, size, degree of refining, degree of matte, density and surface coating and other factors. Uncoated paper usually has a lower density than coated paper.
■ The ink film, dust, and the chemical structure of the practical ink film should be thicker than the surface of the material to ensure the smooth deposition of the ink. Modern photopolymerized plate systems have Shore-A hardness and can overcome uneven paper surface structures. However, the softness of the corrugated flexo plate cannot reach this hardness, which will result in excessive dot gain.
The PET material underneath the printing plate often appears to be incompatible with the printing plate, tape, and corrugated foam, which may result in serious network expansion. The softer the corrugated plates, the easier it is for the press to overcome the problem of surface roughness; however, the clarity of the printed elements will also be reduced and the image elements will be compressed as if they were together.
On the other hand, the use of a thicker ink film during the printing process leads to serious dot gain. The thicker the ink film, the harder it is to dry. Extending the drying time in turn leads to lower printing speeds and increased costs. Low viscosity inks are often used in flexo printing. In this way, the binder is more flexible and can get into the coating more quickly, leaving the pigment on the surface. The image loses gloss and the pigment can be easily wiped off the surface. This situation can easily occur in the direct printing of corrugated paper using inferior backing paper. It is therefore very important to ensure that the absorbency of the liner matches the rheology of the ink.
Dust is clearly another printability problem associated with the printing process. Dust is an accessory for small fragments of paper surfaces and edges. If no ink filtration device is used, dust and dirt can collect in the ink and transfer to the plate. This phenomenon is "dirty output."
The chemical composition of paper also has a certain influence on printability. Excessive acidity in the liner can affect the drying speed of the ink. In general, the Ph value of the uncoated backing material should be 5 or 5.5 or slightly higher, and the coating material should be 7-8.5 in order to ensure the optimum drying time. (To be continued).
Liyang Paper products co., ltd is a factory and trade company located in Dongguan, China. Specialized in producing gift paper packaging and printing, such as gift box, gift bags, book printing, notebooks, folders, wine box,jewelry box, cosmetic box, watch box, shoe box,etc.Custom made base on your design is welcome, feel free to contact Liyang printing with your full details.
November 12, 2024
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November 12, 2024
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Ms. Lily Yu
Tel:86-769-82795922
Fax:86-769-85193253
Mobilní telefon:8613580852389
E-mailem:admin@lyprinting.com
Adresa:Jiumenzhai Jiuzui New District Road, Humen Town, Dongguan City, Guangdong Province, 523999, China., Dongguan, Guangdong
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Prohlášení o ochraně osobních údajů: Vaše soukromí je pro nás velmi důležité. Naše společnost slibuje, že vaše osobní údaje nezveřejní žádné zhoršení bez vašich explicitních povolení.
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Prohlášení o ochraně osobních údajů: Vaše soukromí je pro nás velmi důležité. Naše společnost slibuje, že vaše osobní údaje nezveřejní žádné zhoršení bez vašich explicitních povolení.