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(seven) adhesive layer drying
In the composition of the film coated with the entrained glue, more than 75% is the encapsulant, and only 25% of the solid material has the final adhesion. But these 25% have the final value of the material, only rely on 75% of the olefins melting, alleviation can play its role. Although 75% of the olefins are large, they are only needed during the synthesis and coating process. They are a temporary component and must be evaporated before being combined with the printed matter. It does not evaporate and cannot form a valuable 25% solids material that can produce a strong bond to both the film and the print in both directions. Therefore, the film and the composite material are bonded firmly or not, that is, the foaming is not blistering. The basis is not only the quality of the glue, the concentration of the glue, the thickness of the glue, but more importantly, the entrained material in the glue liquid is volatilized. , whether the glue is dry before compounding.
In order to ensure the dryness of the adhesive layer, the laminating machine is designed with a drying path several meters long. Just want to be in such a long distance, in a closed drying box, through a number of electric heating tube emits uniform heat, and the front of several fans to the drying tunnel, the rear exhaust fan to the outside world, so that Continuously supplying a strong hot air stream volatilizes the entrained material in the glue layer applied on the film surface. There are several situations under these conditions:
1 The olefin is used as the main component of the glue to effect the dissolution and synthesis of the resin. After being dissolved by the resin, the synthesized encapsulant itself is also changed by the dissolved and synthesized substance. The process of dissolution and synthesis is not only a physical process of mixing and morphological changes of several materials, but also a chemical reaction that interacts and reacts with each other to produce new properties. The encapsulants that dissolve the resin and other chemical raw materials, and the encapsulants that are added to meet the coating operations, have a relatively large relative density, boiling point, evaporation rate, flash point, etc. Variety. Just like using tap water to make porridge, after adding rice, beans, and alkaline tap water to make porridge, its composition is no longer just H2O, but there are alkali, starch and other chemical components, and the nature has changed. In such a case, the entrainment of the entrained material in the vapour to the atmosphere is volatilized, and although it is supplemented with the external force conditions of the hot gas stream, it is much slower and much more difficult to volatilize than the pure entrained material. Relevant scientific research departments have done experiments, the pure olefins and the olefins were synthesized, and the diluted adhesives were respectively coated on a 20 μm corona-treated biaxially oriented BOPP film under the same conditions of hot air flow. Baking and drying effect, the residual amount of pure olefin was 21PPm, and the difference between them was 15.33 times. This test shows that the volatilization rate and volatilization amount of the entrained mixture in the glue solution is only 1/15 of the pure encapsulant. Just like a bowl of clean water splashed on the ground, it will quickly infiltrate into the soil, leaving only traces of wetting; and a bowl of rice porridge spilled on the ground, the water in the porridge can not quickly infiltrate into the soil, still stay in the porridge, keep very For the same long time. Therefore, the glue on the film that comes out through the drying tunnel is not a dry solid but a somewhat sticky gel body.
2 Generally, the adhesive layer applied on the film is more than 5um. After the passage through the tunnel, the first thing that evaporates is the encapsulant in the surface glue, just like the rice porridge that has fallen on the ground. Drying starts from the surface first. Ground rice porridge also has another important drying route that is absorbed by the soil. The volatilization of the internal deep olefins can only be achieved by the action of the olefin molecules that breaks through the molecular attractiveness of other substances in the glue and the activity rises to the surface of the glue layer. At this time, the molecules of the encapsulant encounter two difficulties: one is that after the envelop of the surface layer volatilizes, the volume of the adhesive layer will shrink, and it will become a kind of surface “dry-up†and become the activity of the internal deep encapsulant molecules. It is separated from the rubber matrix and evaporated into the lid of the atmosphere; the other is the time needed to overcome the intermolecular attraction from the deep inside and rise to the surface. This time is often longer than when the film passes through the drying tunnel under the action of a high-strength hot air stream. As a result of these two difficulties, the volatilization of the encapsulant in the depth of the adhesive layer is blocked by the surface layer, and forms an illusion that the outer layer does not dry out.
3 When many pilots found such problems during operation, they often used the method of increasing the power of the heating tube in the drying tunnel and increasing the amount of air discharged from the motor. It was hoped that higher temperatures and more wind could cause the encapsulant to evaporate completely. . However, the excessive evaporation of the solvent causes the surface temperature of the adhesive layer to drop rapidly, and the temperature contrast in the small area on the surface of the adhesive layer with the surrounding atmospheric environment. This temperature difference causes the water vapor molecules in the hot air stream to condense into tiny vapors on the surface of the adhesive layer, covering the surface of the adhesive layer and compounding the film with the printed matter. The existence of this kind of water vapor, on the one hand, forms a separation layer of glue and ink printing layer to affect the bonding, on the other hand, it affects the transparency of the adhesive layer after compounding, and the phenomena of whitening and fading occur.
(8) Changes after compounding
The adhesive layer applied on the surface of the film passes through a small light roller-small rubber roller system before passing through the hot press-fitting mechanism. This system determines the initial bonding position of films and films or materials such as film and paper. The gap size not only determines the initial pressure of the film and the composite material, but also affects the operating speed, passing time, and the amount of air discharged, as well as the composite quality.
When the film is composited with the composite material, the encapsulant contained in the “dry-up†adhesive layer still exists. In particular, the active encapsulant molecules in the inner surface of the “dry-up†will continue to move, making the adhesive layer sticky. In a soft state, breaking the bubble and touching the sticky glue is a good illustration.
The encapsulant of the encapsulant is determined by its volatilization properties and must continue to be active after being compounded with the composite material, in order to find ways to escape from the rubber matrix by various means. A part of the adhesive layer skin that has been broken by the pressure of the hot laminating mechanism is “dried†to the inner surface of the film, and the other part gradually moves away from the attraction between the resin molecules of the adhesive layer to reach the surface of the ink layer.
The encapsulant molecules that have polymerized on the inner surface of the film cannot be penetrated through the film due to the gas barrier effect of the film and escape to the atmosphere and evaporate and gradually converge. The thicker encapsulant molecules will swell the film, making the flat, smooth film less bulky due to swelling and forming bubbles. Just as people's hands are soaked in water for a long time, the skin will be swollen with blisters.
The encapsulant molecules that reach the surface of the printing ink layer will have affinity, corrosion, and decomposition with the oils therein, so that the pigment in the ink loses the binding of the oil and becomes scattered particles, which reduces the adhesiveness of the adhesive layer. At the same time, the color printing ink contains a certain amount of chemicals such as additives and thinners. When these encapsulant molecules and the encapsulant molecules in the glue solution are subjected to the air resistance of the BOPP film adhered to the surface thereof, the printing ink layer is formed on the other side by the hot air drying of the crust to form a wrinkle, and only exists in the ink. The convergence under the inner surface of the film further exacerbates the swelling effect on the film, and blistering, whitening, and false voiding are unrealistic.
According to the analysis of the operating procedures, the reason for foaming can basically be understood. The main reason is not that the operator is misconducted or that the sense of responsibility is not strong. However, there is a big difference between the process design and the implementation effect. That is, the coating coating process itself exists. Serious flaws. Its craft is:
Film discharge → coating glue → drying → pressing → winding → storage → slitting → finished products ↑ ↑
Adhesive transfer printing
Plastic/plastic/plastic/metal/paper/plastic composites play a decisive role in plastics. In the glue compounding process, only the olefin (solvent) type glue can be used for operation. In order to facilitate the operation, the material must be re-enforced. Dosage. The increase in the amount of encapsulant, on the one hand, reduces the adhesive force of the glue and on the other hand increases the volatilization of the encapsulant. In the case of “thickness cannot be coated, thin and weak, the strength is not enough, and the thickness is dry. Impervious to such a state of extreme contradiction and unscientific, the elusive blistering problem continues to occur. Of course, if the compounding speed is slower than 300r/min, it will be better, the amount of olefins will be much more volatile, and the ink and glue will be dry, but the production cycle is too tight to allow you to take it slow. Increasing the concentration and increasing the thickness is also a method, but the concentration is increased, the thickness is increased, and the cohesive force generated after the glue is dried is also increased, which not only can not solve the problem of foaming due to swelling, but also occurs a new film folding bubble. bubble.
V. Causes, Effects, and Elimination of Static Electricity Produced by Lamination
As the film-coating technique is reformed from a glued wet compounding process to a hot-melt adhesive precoating film dry compounding process, the fire caused by the static electricity ignited organic solvent volatilization gas generated during the film production process can be eliminated, but the static electricity is applied to the film. The impact of the production process operation still exists. Elimination of static and guaranteeing the smooth progress of film production and reprocessing of its products has become a new topic in the technology of film coating technology, and it has yet to discuss with colleagues.
(a) Causes of static electricity in the film
Film is a composite of BOPP plastic film and other plastic film or paper prints. Before being compounded by the hot laminating mechanism of the special laminating machine, the BOPP plastic film should be rotated by the heated roller in the discharge mechanism and passively discharged. At this time, BOPP plastic film tightly wound together must first pass through several metal flattening rollers, relying on the friction, expansion, and tight fitting with the metal roller, and keeping the BOPP plastic film itself in full-frame. Width flatness and tension consistent. Stacked stacks of paper prints are to be removed from their original position by the workers or through the friction caused by the equipment pulling again and again, and they are sent to the hot-pressing mechanism. The friction between the rubber conveyor belt of the paper conveying mechanism and the driving metal roller causes the conveyor belt to constantly move. Immediately after this, the print with the paper and ink prints or ink prints rubbed against each other immediately entered the double rubbing state with the rubber conveyor belt. There is no double rub between the conveyor belt and the drive roller, between the paper print and the rubber conveyor belt, and it is not possible to form a print that is positioned before the print.
When the hot press mechanism is used, the BOPP plastic film on the surface is rubbed by the metal heating roller. The printed paper on the bottom is strongly squeezed and rubbed by the rubber pressure roller to form the diffusion of adhesive molecules to the print itself. Bonding and compounding of BOPP plastic film, at the same time, is "rolled out" by rolling, leaving the hot pressing mechanism.
The paper/plastic composite product leaving the hot laminating mechanism is pulled by the receiving structure and pulled up for winding. In other words, the paper and the plastic surface are formed into closely intertwined frictional windings and are rolled into semi-finished products.
Semi-finished paper/plastic composites, but also through the pulling of artificial forces, the long strip-like complexes are cut one by one to reduce the original size of the single-finished products. The process of the finished product slitting includes both rotating tangential stripping friction and rake plane overlapping friction.
The entire laminating process is not only the process of BOPP plastic film and paper position changes, but also the process of BOPP plastic film, paper and metal roller, like the contact position of the roller to move and change. All in the plastic film / plastic film, plastic film / metal, paper / ink, paper / film / metal, paper / ink, paper / rubber, plastic / paper between the frictional movement without stopping.
Regardless of the basic material of BOPP plastic film, paper print, ink, metal flat roll, rubber pressure roll, each is composed of molecules and atoms. The atom consists of positively charged nuclei and negatively charged electrons. There are protons and neutrons in the nucleus, neutrons are not charged, and protons are positively charged. The negative charge of an electron is equal to the positive charge of a proton. Under normal circumstances, the total number of electrons and the total number of protons contained in any part of each of the above-mentioned objects are equal to each other, so that no electric power is exhibited to the outside world. Just as paper, BOPP plastic film, and laminating machine are stored separately, there is no release and influence of static electricity when there is no interaction movement and it is still.
However, under certain external forces, such as self-peeling when BOPP plastic film is discharged, friction occurs, friction occurs when BOPP plastic film and metal flat roll runs, friction when paper and paper leave, and paper and rubber pressure roll mill Rolling friction, friction between BOPP plastic film and heated roller, friction between paper and plastic composites, separation of plastic and paper, frictional force, contact distance is one
In the composition of the film coated with the entrained glue, more than 75% is the encapsulant, and only 25% of the solid material has the final adhesion. But these 25% have the final value of the material, only rely on 75% of the olefins melting, alleviation can play its role. Although 75% of the olefins are large, they are only needed during the synthesis and coating process. They are a temporary component and must be evaporated before being combined with the printed matter. It does not evaporate and cannot form a valuable 25% solids material that can produce a strong bond to both the film and the print in both directions. Therefore, the film and the composite material are bonded firmly or not, that is, the foaming is not blistering. The basis is not only the quality of the glue, the concentration of the glue, the thickness of the glue, but more importantly, the entrained material in the glue liquid is volatilized. , whether the glue is dry before compounding.
In order to ensure the dryness of the adhesive layer, the laminating machine is designed with a drying path several meters long. Just want to be in such a long distance, in a closed drying box, through a number of electric heating tube emits uniform heat, and the front of several fans to the drying tunnel, the rear exhaust fan to the outside world, so that Continuously supplying a strong hot air stream volatilizes the entrained material in the glue layer applied on the film surface. There are several situations under these conditions:
1 The olefin is used as the main component of the glue to effect the dissolution and synthesis of the resin. After being dissolved by the resin, the synthesized encapsulant itself is also changed by the dissolved and synthesized substance. The process of dissolution and synthesis is not only a physical process of mixing and morphological changes of several materials, but also a chemical reaction that interacts and reacts with each other to produce new properties. The encapsulants that dissolve the resin and other chemical raw materials, and the encapsulants that are added to meet the coating operations, have a relatively large relative density, boiling point, evaporation rate, flash point, etc. Variety. Just like using tap water to make porridge, after adding rice, beans, and alkaline tap water to make porridge, its composition is no longer just H2O, but there are alkali, starch and other chemical components, and the nature has changed. In such a case, the entrainment of the entrained material in the vapour to the atmosphere is volatilized, and although it is supplemented with the external force conditions of the hot gas stream, it is much slower and much more difficult to volatilize than the pure entrained material. Relevant scientific research departments have done experiments, the pure olefins and the olefins were synthesized, and the diluted adhesives were respectively coated on a 20 μm corona-treated biaxially oriented BOPP film under the same conditions of hot air flow. Baking and drying effect, the residual amount of pure olefin was 21PPm, and the difference between them was 15.33 times. This test shows that the volatilization rate and volatilization amount of the entrained mixture in the glue solution is only 1/15 of the pure encapsulant. Just like a bowl of clean water splashed on the ground, it will quickly infiltrate into the soil, leaving only traces of wetting; and a bowl of rice porridge spilled on the ground, the water in the porridge can not quickly infiltrate into the soil, still stay in the porridge, keep very For the same long time. Therefore, the glue on the film that comes out through the drying tunnel is not a dry solid but a somewhat sticky gel body.
2 Generally, the adhesive layer applied on the film is more than 5um. After the passage through the tunnel, the first thing that evaporates is the encapsulant in the surface glue, just like the rice porridge that has fallen on the ground. Drying starts from the surface first. Ground rice porridge also has another important drying route that is absorbed by the soil. The volatilization of the internal deep olefins can only be achieved by the action of the olefin molecules that breaks through the molecular attractiveness of other substances in the glue and the activity rises to the surface of the glue layer. At this time, the molecules of the encapsulant encounter two difficulties: one is that after the envelop of the surface layer volatilizes, the volume of the adhesive layer will shrink, and it will become a kind of surface “dry-up†and become the activity of the internal deep encapsulant molecules. It is separated from the rubber matrix and evaporated into the lid of the atmosphere; the other is the time needed to overcome the intermolecular attraction from the deep inside and rise to the surface. This time is often longer than when the film passes through the drying tunnel under the action of a high-strength hot air stream. As a result of these two difficulties, the volatilization of the encapsulant in the depth of the adhesive layer is blocked by the surface layer, and forms an illusion that the outer layer does not dry out.
3 When many pilots found such problems during operation, they often used the method of increasing the power of the heating tube in the drying tunnel and increasing the amount of air discharged from the motor. It was hoped that higher temperatures and more wind could cause the encapsulant to evaporate completely. . However, the excessive evaporation of the solvent causes the surface temperature of the adhesive layer to drop rapidly, and the temperature contrast in the small area on the surface of the adhesive layer with the surrounding atmospheric environment. This temperature difference causes the water vapor molecules in the hot air stream to condense into tiny vapors on the surface of the adhesive layer, covering the surface of the adhesive layer and compounding the film with the printed matter. The existence of this kind of water vapor, on the one hand, forms a separation layer of glue and ink printing layer to affect the bonding, on the other hand, it affects the transparency of the adhesive layer after compounding, and the phenomena of whitening and fading occur.
(8) Changes after compounding
The adhesive layer applied on the surface of the film passes through a small light roller-small rubber roller system before passing through the hot press-fitting mechanism. This system determines the initial bonding position of films and films or materials such as film and paper. The gap size not only determines the initial pressure of the film and the composite material, but also affects the operating speed, passing time, and the amount of air discharged, as well as the composite quality.
When the film is composited with the composite material, the encapsulant contained in the “dry-up†adhesive layer still exists. In particular, the active encapsulant molecules in the inner surface of the “dry-up†will continue to move, making the adhesive layer sticky. In a soft state, breaking the bubble and touching the sticky glue is a good illustration.
The encapsulant of the encapsulant is determined by its volatilization properties and must continue to be active after being compounded with the composite material, in order to find ways to escape from the rubber matrix by various means. A part of the adhesive layer skin that has been broken by the pressure of the hot laminating mechanism is “dried†to the inner surface of the film, and the other part gradually moves away from the attraction between the resin molecules of the adhesive layer to reach the surface of the ink layer.
The encapsulant molecules that have polymerized on the inner surface of the film cannot be penetrated through the film due to the gas barrier effect of the film and escape to the atmosphere and evaporate and gradually converge. The thicker encapsulant molecules will swell the film, making the flat, smooth film less bulky due to swelling and forming bubbles. Just as people's hands are soaked in water for a long time, the skin will be swollen with blisters.
The encapsulant molecules that reach the surface of the printing ink layer will have affinity, corrosion, and decomposition with the oils therein, so that the pigment in the ink loses the binding of the oil and becomes scattered particles, which reduces the adhesiveness of the adhesive layer. At the same time, the color printing ink contains a certain amount of chemicals such as additives and thinners. When these encapsulant molecules and the encapsulant molecules in the glue solution are subjected to the air resistance of the BOPP film adhered to the surface thereof, the printing ink layer is formed on the other side by the hot air drying of the crust to form a wrinkle, and only exists in the ink. The convergence under the inner surface of the film further exacerbates the swelling effect on the film, and blistering, whitening, and false voiding are unrealistic.
According to the analysis of the operating procedures, the reason for foaming can basically be understood. The main reason is not that the operator is misconducted or that the sense of responsibility is not strong. However, there is a big difference between the process design and the implementation effect. That is, the coating coating process itself exists. Serious flaws. Its craft is:
Film discharge → coating glue → drying → pressing → winding → storage → slitting → finished products ↑ ↑
Adhesive transfer printing
Plastic/plastic/plastic/metal/paper/plastic composites play a decisive role in plastics. In the glue compounding process, only the olefin (solvent) type glue can be used for operation. In order to facilitate the operation, the material must be re-enforced. Dosage. The increase in the amount of encapsulant, on the one hand, reduces the adhesive force of the glue and on the other hand increases the volatilization of the encapsulant. In the case of “thickness cannot be coated, thin and weak, the strength is not enough, and the thickness is dry. Impervious to such a state of extreme contradiction and unscientific, the elusive blistering problem continues to occur. Of course, if the compounding speed is slower than 300r/min, it will be better, the amount of olefins will be much more volatile, and the ink and glue will be dry, but the production cycle is too tight to allow you to take it slow. Increasing the concentration and increasing the thickness is also a method, but the concentration is increased, the thickness is increased, and the cohesive force generated after the glue is dried is also increased, which not only can not solve the problem of foaming due to swelling, but also occurs a new film folding bubble. bubble.
V. Causes, Effects, and Elimination of Static Electricity Produced by Lamination
As the film-coating technique is reformed from a glued wet compounding process to a hot-melt adhesive precoating film dry compounding process, the fire caused by the static electricity ignited organic solvent volatilization gas generated during the film production process can be eliminated, but the static electricity is applied to the film. The impact of the production process operation still exists. Elimination of static and guaranteeing the smooth progress of film production and reprocessing of its products has become a new topic in the technology of film coating technology, and it has yet to discuss with colleagues.
(a) Causes of static electricity in the film
Film is a composite of BOPP plastic film and other plastic film or paper prints. Before being compounded by the hot laminating mechanism of the special laminating machine, the BOPP plastic film should be rotated by the heated roller in the discharge mechanism and passively discharged. At this time, BOPP plastic film tightly wound together must first pass through several metal flattening rollers, relying on the friction, expansion, and tight fitting with the metal roller, and keeping the BOPP plastic film itself in full-frame. Width flatness and tension consistent. Stacked stacks of paper prints are to be removed from their original position by the workers or through the friction caused by the equipment pulling again and again, and they are sent to the hot-pressing mechanism. The friction between the rubber conveyor belt of the paper conveying mechanism and the driving metal roller causes the conveyor belt to constantly move. Immediately after this, the print with the paper and ink prints or ink prints rubbed against each other immediately entered the double rubbing state with the rubber conveyor belt. There is no double rub between the conveyor belt and the drive roller, between the paper print and the rubber conveyor belt, and it is not possible to form a print that is positioned before the print.
When the hot press mechanism is used, the BOPP plastic film on the surface is rubbed by the metal heating roller. The printed paper on the bottom is strongly squeezed and rubbed by the rubber pressure roller to form the diffusion of adhesive molecules to the print itself. Bonding and compounding of BOPP plastic film, at the same time, is "rolled out" by rolling, leaving the hot pressing mechanism.
The paper/plastic composite product leaving the hot laminating mechanism is pulled by the receiving structure and pulled up for winding. In other words, the paper and the plastic surface are formed into closely intertwined frictional windings and are rolled into semi-finished products.
Semi-finished paper/plastic composites, but also through the pulling of artificial forces, the long strip-like complexes are cut one by one to reduce the original size of the single-finished products. The process of the finished product slitting includes both rotating tangential stripping friction and rake plane overlapping friction.
The entire laminating process is not only the process of BOPP plastic film and paper position changes, but also the process of BOPP plastic film, paper and metal roller, like the contact position of the roller to move and change. All in the plastic film / plastic film, plastic film / metal, paper / ink, paper / film / metal, paper / ink, paper / rubber, plastic / paper between the frictional movement without stopping.
Regardless of the basic material of BOPP plastic film, paper print, ink, metal flat roll, rubber pressure roll, each is composed of molecules and atoms. The atom consists of positively charged nuclei and negatively charged electrons. There are protons and neutrons in the nucleus, neutrons are not charged, and protons are positively charged. The negative charge of an electron is equal to the positive charge of a proton. Under normal circumstances, the total number of electrons and the total number of protons contained in any part of each of the above-mentioned objects are equal to each other, so that no electric power is exhibited to the outside world. Just as paper, BOPP plastic film, and laminating machine are stored separately, there is no release and influence of static electricity when there is no interaction movement and it is still.
However, under certain external forces, such as self-peeling when BOPP plastic film is discharged, friction occurs, friction occurs when BOPP plastic film and metal flat roll runs, friction when paper and paper leave, and paper and rubber pressure roll mill Rolling friction, friction between BOPP plastic film and heated roller, friction between paper and plastic composites, separation of plastic and paper, frictional force, contact distance is one
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