Viewing the quality of perfect binding from the change of bonding dynamics
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
The use of bonding technology for bookbinding is an old and practical technique. With the development of science and technology, natural products (bone glue, starch, etc.) have been used as adhesives to enter a new development period of polymer blending and polymerization to form multi-component synthetic adhesives. The replacement of flat binding by wireless binding has fundamentally changed the backward state of the post-pressing process, ensuring the rapid development of the printing industry as a whole.
In the early stages of the alternate update of the wireless binding and the new technology, there will inevitably be some problems. The main performance is that after binding into a book by using the binding technology, there are problems such as batch droppage, falling frame, difficulty in unfolding, and deformation of the spine after turning. Even the senior leaders were alarmed, so that the printing industry's old predecessors issued the "adhesive without passing" advice. The industry authorities also proposed the overall layout of the year 2000 as the quality of the binding.
Why are these problems occurring? Even the world-class Martini linkage production line is not immune?
The key lies in the unique characteristics and advantages of the bonding body (book block and cover), bonding material (adhesive hot melt adhesive) and adhesive (adhesive binding machine), which cannot be comprehensively played in the binding production process. New dynamic changes in production conditions constrain damage.
First, the bond body (book block and cover)
The rapid development of the market economy has driven the prosperity of the news and publishing industry, and the quality and quantity of China's paper industry and its products have continuously hit record highs. In order to improve the quality of paper in China, special sizing agent, dispersing agent, flocculating agent, defoaming agent, lubricant, adhesive, waterproofing agent, anti-adhesive agent, moisturizing agent, release agent, softener, anti-mold agent, retention The application of auxiliary chemical products such as agents and filter aids opens up a broad prospect for improving the production process and product characteristics of pulp, paper and paperboard. Mastering the characteristics and technical requirements of caustic soda, bleach, fillers, coatings, and accurately controlling the quantity used is an important part of the stable pulping and papermaking process.
As the bookbinding and cover paper of the wireless adhesive binding body, although it is developed in the direction of coated paper (adhesive paper, coated paper), it is still biased on the cover for a large number of primary and secondary school textbooks and general books. The distinction between coated paper (offset paper, coated paper) and plain paper (profile paper, offset paper).
The main source of the raw paper is wood pulp fiber. The wood pulp used in the base paper has three categories: chemical softwood pulp, chemical hardwood pulp, and mechanical wood pulp. In general, the "hardwood" has 10 times more fiber per unit volume than "softwood"; the northern wood has a smaller fiber size than the southern wood; the softwood fiber is longer and stronger. However, the wood species also has the southern yellow pine of softwood fiber, the red rubber tree of western hemlock and hardwood fiber, birch, white cedar, oak, eucalyptus and the like. The difference in fiber size, the "fines" produced after being beaten or refined, will fill the gaps in the fiber layer, and determine the smoothness, uniformity, opacity, etc. of the base paper.
In the chemical method, lignin and resin and the like together with the fibers are dissolved in the cooking process and separated from the fibers by washing, and finally bleached to obtain a bleaching slurry. Alkaline systems have the potential to replace fibers with fillers. The amount of paper given by the filler also reduces the paper strength.
The fibers constituting the base paper have a diameter of 20 um to 65 um even after the pulping process of semi-prep (or beating), pressing and drying, and the base paper is subjected to water-swelling and cellulose-decomposing in the papermaking process. Each cycle of "wet" and "dry" increases the roughness of the original paper surface.
The fine grinding process of the base paper into a pulp, when the fibers are excessively cut, the result is that the fiber length becomes short.
The proportion of forest area in China is very small. Wood pulp for papermaking is basically imported. In order to protect forest resources and reduce the cost of papermaking, in the past 20 years, the fast-growing forests have not been clustered before and for the protection of the ecological environment. The non-wood pulp is mixed with the base paper, coated base paper and coated raw paperboard, which has been adopted and will continue to be adopted. The essential ratio and process are implemented in China's paper industry.
It means that whether it is cover paper or text paper in the perfect binding adhesive, compared with advanced foreign countries, there are defects such as rough surface, low strength, easy to pull off powder and so on. Under the new conditions of pre-press popular electronic color separation, laser photo-alignment and multi-color high-speed equipment for printing applications, the printing cycle is greatly shortened, and the requirements for binding are both good and fast. The dynamic new reaction on the bond is:
1. The inner core of the surface is rough, the strength is low, and the powder is easy to pull off. The cutting surface of the milling cutter is not a smooth and smooth interface, but the spine coating surface and the edge of the milling slot are fluffed. Velvet convex obstacle. It not only reduces the machining geometry of the bond, but also changes the state of the bond interface, while blocking the wetting and filling of the bond surface by the hot melt fluid within a specified time.
2, fast printing on the binding processing without the long time interval interval requirements, paper, especially the non-textographic binding book ridge part of the moisture absorbed by the outside can not be distributed to the outside, so that the internal album in the high moisture content into the binding production line . There will be three new phenomena happening:
2.1 After the book is glued into a book, the water content of the internal album is gradually volatilized, causing the paper to shrink and shrinking in the same proportion with the milling groove. Separation of the "slot large inlay" that is loosely bonded to the glued hot melt adhesive;
2.2 The internal album is in contact with the glued hot melt adhesive. The high temperature (170oC) hot melt colloid promotes the evaporation of moisture on the surface of the album. At the same time, the applied hot melt adhesive does not allow the water vapor that escapes to the surrounding atmosphere to press against the book bonding interface. Volatile and contained water vapor molecules, which are a newly formed dispersed separation layer between the colloid and the bond, and cause gelation on the surface of the molten hot melt adhesive. The overall fluidity is changed and destroyed, and the spine is reduced. Wetting and filling of the milling groove. In particular, the milling groove is more severely blocked by the fiber fluff produced by cutting.
Second, bonding materials (adhesive hot melt adhesive)
The back surface of the book block that has been subjected to the milling back groove surface is evenly coated with a certain thickness (width) of the adhesive material through the glue roller of the perfect binding machine - the adhesive hot melt adhesive is then automatically transported. Cover bonding. Curing occurs as the adhesive diffuses, rheological, infiltrates, merges, and drops in temperature. When the distance between the macromolecule of the adhesive and the surface of the adherend is less than 5A, they will attract each other, generate van der Waals force or form hydrogen bonds, covalent bonds, coordination bonds, ionic bonds, etc., and insert the wedge colloid into the milling groove. The binding process is completed by the infiltration of the adhesive that penetrates into the pores to create a myriad of small "glue hooks".
Due to the objective reality of the structure and surface state of the former self-adhesive, the poor aging resistance of the bonding material synthesis, and the inevitable aging of the coating process, the peeling strength and unevenness of the bonding layer are peeled off. Strength, impact strength and low temperature toughness are low. At present, the industry lacks effective non-destructive testing methods and adaptive technical standards for the quality control of bonding materials, so that the binding enterprises can hardly distinguish the bonding materials of the hot-melt adhesives, and pay after the binding construction. In order to verify the great cost of quality.
The problem lies in the production process and the selection and configuration of raw materials for synthesis and use.
Conventional kettle-type production methods can cause aging of the binder during the synthesis process due to errors that cannot be precisely controlled by temperature control and conduction.
The advanced rod extrusion production method has high viscosity and different softening points due to the processing object, and the uneven blending often occurs.
In order to improve the affinity of the paper-hair-attached spine after surface treatment, it is necessary to increase the amount of tackifying resin, which is a gene that affects the impact strength and self-aging.
In order to ensure a rapid and full filling of the milling groove, it is necessary to increase its fluidity. The quality and quantity of the modifier used in turn affects its own peel strength and low temperature toughness.
Manufacturers of hot melt adhesives with extremely different technical content grab the market at low prices and engage in unfair competition. Binding and processing enterprises purchase at a price rather than a quality, and push the hot melt adhesive to advance production misunderstanding from both supply and demand.
Third, the adhesive (adhesive machine)
Each year, the bookbinding process of 7 billion books (including 3.6 billion textbooks) has promoted the development of bookbinding machinery. At present, the binding company uses 480~600 copies/hour strip-type binding machine, 900~4000 copies/hour of the original package, and most of them are not equipped with frequency conversion system. It is difficult to ensure the consistency of the depth and spacing of the milling groove in the actual production operation process. The binding-linking line milling cutter pallet is seriously worn during the processing of the domestic paper printed matter, and the replacement is more diligent. After the replacement, the deviation of the front, back, left and right is also easy to occur, which affects the standard of milling back slotting.
A serious problem is the open structure of the upper opening of the glue tank and the volume of the coating which is more than 2 hours.
The glue groove and the rotating roller rubber wheel which are easy to apply and open, increase the contact area of the hot melt adhesive with air to promote sufficient oxidation. In order to ensure uniform coating, the reserve of a large amount of hot melt adhesive, and the heating temperature that has been kept at the time of storage, it is the source of rapid aging of the hot melt adhesive and reduction of strength. The drawing of the glue on the perfect binding machine is the aging mark of the coated or uncoated glue.
In addition, the quality of the heating element itself and the sensitive difference cause the error of the temperature display of the glue tank to be higher than 100oC, which is not only difficult to control the aging of the colloid, but also to ensure the overall good fluidity when adding a new rubber compound.
Fourth, adapt to improve
Based on the current state of the bond and advances in printing technology, the bond and bonder should be technically modified to accommodate the bond. Fundamentally, the basis for determining the quality of binding is the quality of the glued hot melt adhesive and the stability of the adhesive binding production process.
1. As a bonding material, the synthetic process of binding hot melt adhesive should be based on ensuring the stability of blending modification.
The selection of raw materials for the polymerization components should be based on ensuring quality. Through the use of new and excellent materials, the contradiction between viscosity and strength, strength and softening point, softening point and fluidity, fluidity and toughness are mutually affected and mutually affected.
It is necessary to change the design thinking that simply changes the temperature to change the fluidity and ensure the glue effect. Established an innovative technology for the development of low-temperature (≤130oC) bottom and edge rubber universal new adhesive hot melt adhesive. Completely solve the deterioration of the mass due to high temperature (≥170oC) melting. The new type of glued hot melt adhesive should have the advantages of small specific gravity (≤0.95), consumption (0.5~1.3mm for spine flat coating), good compatibility with paper fiber fluff and affinity.
2. The milling cutter of the binding machine should be replaced regularly to maintain sharpness and a good working interface.
The pallet should be calibrated to ensure that the work surface is consistent.
Check the accuracy of the colloidal melting electric heating element, master the basic error, and change the glue tank under the premise of ensuring uniform coating. Try to reduce the amount of glue in the melt tank. At the same time, it is equipped with a pre-melting tank (≤100oC) secondary glue supply device which is quantitatively supplied according to the coating requirements.
Clean the brush reader in time, carefully maintain and repair the suction device to ensure that the paper scrap is completely separated from the book block album.
3. Carry out technical training for production management and operators to improve their theoretical level and operational skills. Can better deal with problems in the production process.
4. As soon as possible, formulate the “Fixed Hot Melt Adhesive Technology Standard” to ensure the quality of the binding and the “Hot Melt Adhesive Quality Standard Inspection Method” for the convenience of binding enterprises, standardize the production and use of hot melt adhesives, and prevent the listing and use of non-standard products.