In the past two decades, the coated film has been used as a surface finishing process for printed products after printing with solid-phase material films. It has been widely used in domestic printing, packaging, and surveying and mapping industries. However, the pollution caused by the production process, the end of the use of laminated products, the difficulty in recycling the resources when they are used, and the awareness of environmental protection that the thin film is easy to associate with “white pollutionâ€, so that the people in the industry and society can And doubts can continue to apply.
Can glazing replace film? Can gloss guarantee mechanical strength? What is the status of the film and future development trends? Has become a concern in the industry.
First, the status of the film
1. Obvious effect
With the advancement of social civilization and the development of the market economy, people are increasingly demanding the printing quality and surface finish effects of paper-based publications and packaging; and the barrier-to-standard and light-proof capabilities of synthetic substrates for plastic color-printed flexible packaging. The requirements for reliability such as odor-free migration are continuously increasing, and the film-covering industry is encouraged to change the extensive processing of single materials and traditional processes, and a variety of technological innovation processes such as solvent-free dry compounding and non-polluting and non-toxic cleaning raw materials are used for papermaking. / Plastic composite or plastic / plastic, plastic / metal and other substrates, a variety of layers of film composite.
Paper-based publications, packaging, and other printed matter are printed and film-finished after printing. The graphic and text are protected and the visual effect is better. In particular, the matt film has no wide-angle, excessive-light diffuse reflection, and gives people softer, Deep, noble, luxurious new feeling. The film can increase the depth and brightness of the color and improve the color contrast so that the graphic can be waterproof, non-sticky, oil-resistant, and abrasion-resistant. To improve the physical and mechanical strength of paper tension, smoothness, photoaging, tear resistance, anti-jamming, etc., and to suppress the physical properties of moisture absorption, to reduce the deformation and breakage caused by the influence of moisture on paper products, and to improve the rigidity and molding of the products. stability. The coated paper or plastic is no longer a single carrier for graphic color representation. Defects in paper or plastic are compensated by BOPP plastic film, which effectively protects the core of the book or packaged goods, facilitating the design, operation, transportation, storage, display and consumer use. Even after exposure to sunlight, post-laminated prints can delay the fading process. According to statistics, good packaging can increase sales by 15-18%. The investment in the cost of post-press finishing film is far lower than the increase in product added value, product promotion rate, and safe and convenient use value.
According to incomplete statistics, there were 71,150 kinds of books published in 1999, about 2.076 billion volumes, equivalent to 259,500 reams of cover paper, 14,528 kinds of textbooks, about 2.665 billion volumes, and 336,300 copies of cover paper. Orders; 2866 periodicals, about 996 million copies, 249,600 reams of cover paper, all using coated precision finishing methods. Excluding the packaging of video products, only 88.5 million kinds of books, textbooks, and periodicals were covered with about 8.85 million sheets, 5.737 billion sheets, and 3,841,700 reams. The use of film is about 9,415 tons, with an output value of 19,200,000 yuan, accounting for 1.5% of the total output value of the national book and book printing industry. Except for publications such as textbooks, books, periodicals, advertisements, photo albums, wall charts, and other paper products, such as cartons, cartons, and paper bags for wine, food, medicine, clothing, shoes, hats, electronics, and home appliances, etc. , Paper / plastic composite and continue to the vegetables, fruits, pesticides, food, seeds, feed, cosmetics, hardware, daily necessities, soft drinks, handicrafts and other industries.
The plastic color printing flexible packaging industry has made progress in the intaglio printing technology of BOPP film to flexible printing and printing technology, which has reduced the cost, shortened the cycle, and enlarged the composite concept. With the advancement of science and technology and the production of new and superior materials, the film is no longer a simple single-layer composite of BOPP/PE, BOPP/PET, BOPP/CPP, and BOPP/BOPP (single-sided heat-sealing) substrates. Instead, BOPP is used as a matrix for the compatibility of multi-layered composites and multi-layer co-extruded substrates, or ultra-thin metallic webs, for printing substrates and various substrates. The technological innovation enables BOPP to be used as an intermediate and can be combined with other substrates to form a new type of composite material with superior performance.
The rapid development of the film-covered industry with paper/plastic and plastic/plastic composites as the mainstay has driven plastic packaging materials, books and periodicals, and packaging and printing. The rapid development of various laminating machinery, different types of adhesives and other industries. The new composite material industry has already formed in China. The innovation of film-covering technology has promoted the development of packaging improvement work and the development of China's economy.
2. Problems that exist
The advancement of printing technology, the updating of printed materials and other prerequisites for the constraints of the film, and the influence of changing factors of the post-press processing conditions on the film, as well as the improvement of the printing quality standards and market demands, require that the film-covering industry must press the objective Changes in conditions and structural adjustments to new quality and technical standards. Due to various factors, adjustments that should be made often lag behind. As a result, there are certain problems in the production process and product quality assurance.
The main manifestations of these problems are: backward production processes, improper use of raw materials, random technical operation, and low knowledge content.
(1) The production process is backward
Currently accounting for 96% of the book and book printing industry, 88% of advertising production, 90% of the packaging industry, 10% of the surveying and mapping industry, and 98% of other industries. The coating processing methods for paper/plastic composites or plastic/plastic composites still use the instant glue. Wet composite process. That is, when the film is produced, the adhesive is applied on the BOPP film on line and dried and then compounded after drying the device.
In this production process, the in-line coating operation must be completed after the solid resin is dissolved in the liquid organic solvent to synthesize the liquid adhesive; the organic solvent in the liquid adhesive must be volatilized and then reduced to a solid material before the bonding can be completed. This kind of design that depends on phase change to perform construction operations is not only a cumbersome act, but also a self-contradictory between motivation and effect. A large number of facts and experiments have proved that this kind of glue-bonded composite production process is the production process of pollution, sudden fire, wood sticky effect, late adhesive decay, composite material curling, graphic color change, Causes the source of odor migration.
(2) Improper use of raw materials
Adhesives for film coating are available in one-component and two-component adhesives. In order to reduce costs and facilitate operation, except for high-temperature cooking and vacuum-packed composites, most other types of coated films use one-component adhesives.
The main adhesive resin of one-component adhesives is mostly SBS. SBS (styrene-butadiene-styrene block copolymer) is a rubber elastomer material. Although there is a wide range of adhesive properties and a good initial tack effect, it is difficult to completely dry the cured, sub-sensitive adhesive. The synthesis of one-component adhesives depends on aromatic hydrocarbons such as benzene, toluene and other organic solvents. Its flash point is -11.1°C and 4.4°C, respectively. The pure solvent specific evaporation rate is 5 times and 1.95 times the butyl acetate, respectively. The organic solvent swells the BOPP film and increases the thickness and weight of the film by 3.6% and 12.8%, respectively. When the organic solvent is synthesized into an adhesive, the evaporation rate is reduced by more than 15.3%. This data indicates that the drying time given in the film production process is far from ensuring complete volatilization of the organic solvent. On the one hand, Xu Fu caused a large amount of mixed solvent residues in the adhesive on the BOPP film, which reduced the realization of the thermoplastic curability, increased the performance of the sub-sensitive non-dryness, and made the initial viscous strength under the external conditions of hot pressing. Gradually attenuate; at the same time, during the hot press and during the post-cure stage, the movement of the organic solvent molecules mixed in the adhesive increases the swell of the BOPP film, and also causes the cut-off damage to the oil-pigment linkage of the ink and exacerbates. BOPP/ink printing exhibition/composite material's erosion resistance decomposition. On the other hand, the continuous evaporation of organic solvents in the production process (a displacement of a laminator with a width of 800mm is 40m3/min), which increases the concentration of organic solvents in the space around the equipment and is easily generated by the BOPP film material. The electrostatic spark ignites a sudden fire; at the same time, it causes the deterioration of the working conditions in the production environment, allowing the production operator to absorb vapors of benzene-based organic solvents with a content of 40% to 65% from the air, damaging the brain, adrenal glands, liver and blood, and destroying them. Human health.
Two-component adhesives are based on polyester adhesives. By adding a curing agent, the isocyanate is brought into contact with the active hydrogen in the main agent splitter, and a cross-linking reaction occurs in the glue solution to generate a urethane structure and a cross-linked product having a steric conformation with a branched chain structure, having high cohesive force. . However, after the aromatic polyester adhesive is used as a composite packaging material for cooking foods, its main raw material, toluene diisocyanate (TDI), will become aromatic amines after hydrolysis. Aromatic gum migrates through the inner plastic film to food, potentially causing cancer.
(3) Free of technical operation
There are three main types of performance:
The first manifestation is the use of raw materials that are not quantified. There is a lack of scientific and quantitative control over the concentration of adhesives and diluents and the thickness of the adhesive coating.
Randomly change the concentration ratio and the coating thickness specified by the technical department to ensure that the dry basis weight is applied. For the purpose of rapid drying, add more diluent; in order to increase the adhesion, increase the coating thickness. The result is to reduce the relay and increase the swelling of the substrate, destroying the composite effect.
The second manifestation is the free change of equipment operation control parameters. For the normalized equipment parameters such as temperature setting value, air volume setting value, pressure setting value, speed setting value, tension control value, etc., in order to catch up with the production, the method of increasing the temperature and increasing the air volume is used to obtain the adhesive coating. The drying of the layer (temperature increase will only accelerate the coating crust of the glue, which will adversely affect the volatilization of the organic solvent in the middle and deep layers of the coating; the increase of air volume will only lead to a sharp drop in the temperature of the surface of the adhesive coating, so that the drying tunnel The space forms a special microclimate that is hot and cold, and the moisture of the upper hot air rapidly condenses out on the surface of the lower relatively cold adhesive coating to become a kind of disperse phase barrier adhesive and the composite substrate is bonded; or directly improve the machine The operating speed makes the actual use value of the set input data significantly lower (when the operating speed increases from 12m/min to 15m/min in increments of 1m/min, the working pressure drops by It is 8%, 17.5%, and 27%; the decrease in operating temperature is 13%, 27%, and 41%, respectively).
The third manifestation is not good at summing up lessons learned. Can not insist on the basis of raw materials, composites, climate and other objective conditions, the initial setting of the construction program for each batch of processed products first sample test, quality testing, and appropriate adjustments to repeat the test after the batch construction work procedures. According to subjective experience, random mass production can easily result in the loss of targeted construction plans.
(4) Low knowledge content
Lamination is a labor-intensive production process. The fixed processing mode, simple mechanical equipment, and repeated manual operations cover the physics, chemical changes, and inclusive multi-disciplinary knowledge of mechanical, light, chemical, electronics, meteorology, heat, and color. Lamination is actually an integrated product of cutting-edge science and technology and cross-cutting science and technology. It is an initial project of compound technology implementation and composite material manufacturing. Due to a process attributed to postpress processing, linear space is difficult to attract experts and scholars to further study. For a relatively long period of time, it has been developing with a small amount of investment, quick and rapid development, and extensive repetitive operations based on habits and experiences.
3. Innovative technology
(1) The glue-applied wet compounding process has turned to the use of emulsion adhesive (namely known as water-based adhesive)
To solve the pollution and sudden fire caused by the coating process, the solvent-based adhesive for the film has been gradually applied to poly vinyl acetate (PVDC), polyacrylate (PMMA), and other auxiliary materials in the dispersion medium. Under the action of an initiator, an anionic or non-ionic emulsifier, a synthetic polymer suspension type adhesive that is homopolymerized or copolymerized to dissolve in water is replaced by a certain procedure and ratio.
(2) New hot melt adhesive pre-coated film and composite technology have been applied to promote
Through the optimization of EVA, APP, PA and other host materials and formulas. The new type of hot melt adhesive, which is produced by the temperature-controlled synthetic new-type film hot-melt adhesive and the solvent-free melt quantitative coating technology with automatic temperature control, has become a new type of composite material that is pollution-free, non-toxic and safe. Use this new type
Can glazing replace film? Can gloss guarantee mechanical strength? What is the status of the film and future development trends? Has become a concern in the industry.
First, the status of the film
1. Obvious effect
With the advancement of social civilization and the development of the market economy, people are increasingly demanding the printing quality and surface finish effects of paper-based publications and packaging; and the barrier-to-standard and light-proof capabilities of synthetic substrates for plastic color-printed flexible packaging. The requirements for reliability such as odor-free migration are continuously increasing, and the film-covering industry is encouraged to change the extensive processing of single materials and traditional processes, and a variety of technological innovation processes such as solvent-free dry compounding and non-polluting and non-toxic cleaning raw materials are used for papermaking. / Plastic composite or plastic / plastic, plastic / metal and other substrates, a variety of layers of film composite.
Paper-based publications, packaging, and other printed matter are printed and film-finished after printing. The graphic and text are protected and the visual effect is better. In particular, the matt film has no wide-angle, excessive-light diffuse reflection, and gives people softer, Deep, noble, luxurious new feeling. The film can increase the depth and brightness of the color and improve the color contrast so that the graphic can be waterproof, non-sticky, oil-resistant, and abrasion-resistant. To improve the physical and mechanical strength of paper tension, smoothness, photoaging, tear resistance, anti-jamming, etc., and to suppress the physical properties of moisture absorption, to reduce the deformation and breakage caused by the influence of moisture on paper products, and to improve the rigidity and molding of the products. stability. The coated paper or plastic is no longer a single carrier for graphic color representation. Defects in paper or plastic are compensated by BOPP plastic film, which effectively protects the core of the book or packaged goods, facilitating the design, operation, transportation, storage, display and consumer use. Even after exposure to sunlight, post-laminated prints can delay the fading process. According to statistics, good packaging can increase sales by 15-18%. The investment in the cost of post-press finishing film is far lower than the increase in product added value, product promotion rate, and safe and convenient use value.
According to incomplete statistics, there were 71,150 kinds of books published in 1999, about 2.076 billion volumes, equivalent to 259,500 reams of cover paper, 14,528 kinds of textbooks, about 2.665 billion volumes, and 336,300 copies of cover paper. Orders; 2866 periodicals, about 996 million copies, 249,600 reams of cover paper, all using coated precision finishing methods. Excluding the packaging of video products, only 88.5 million kinds of books, textbooks, and periodicals were covered with about 8.85 million sheets, 5.737 billion sheets, and 3,841,700 reams. The use of film is about 9,415 tons, with an output value of 19,200,000 yuan, accounting for 1.5% of the total output value of the national book and book printing industry. Except for publications such as textbooks, books, periodicals, advertisements, photo albums, wall charts, and other paper products, such as cartons, cartons, and paper bags for wine, food, medicine, clothing, shoes, hats, electronics, and home appliances, etc. , Paper / plastic composite and continue to the vegetables, fruits, pesticides, food, seeds, feed, cosmetics, hardware, daily necessities, soft drinks, handicrafts and other industries.
The plastic color printing flexible packaging industry has made progress in the intaglio printing technology of BOPP film to flexible printing and printing technology, which has reduced the cost, shortened the cycle, and enlarged the composite concept. With the advancement of science and technology and the production of new and superior materials, the film is no longer a simple single-layer composite of BOPP/PE, BOPP/PET, BOPP/CPP, and BOPP/BOPP (single-sided heat-sealing) substrates. Instead, BOPP is used as a matrix for the compatibility of multi-layered composites and multi-layer co-extruded substrates, or ultra-thin metallic webs, for printing substrates and various substrates. The technological innovation enables BOPP to be used as an intermediate and can be combined with other substrates to form a new type of composite material with superior performance.
The rapid development of the film-covered industry with paper/plastic and plastic/plastic composites as the mainstay has driven plastic packaging materials, books and periodicals, and packaging and printing. The rapid development of various laminating machinery, different types of adhesives and other industries. The new composite material industry has already formed in China. The innovation of film-covering technology has promoted the development of packaging improvement work and the development of China's economy.
2. Problems that exist
The advancement of printing technology, the updating of printed materials and other prerequisites for the constraints of the film, and the influence of changing factors of the post-press processing conditions on the film, as well as the improvement of the printing quality standards and market demands, require that the film-covering industry must press the objective Changes in conditions and structural adjustments to new quality and technical standards. Due to various factors, adjustments that should be made often lag behind. As a result, there are certain problems in the production process and product quality assurance.
The main manifestations of these problems are: backward production processes, improper use of raw materials, random technical operation, and low knowledge content.
(1) The production process is backward
Currently accounting for 96% of the book and book printing industry, 88% of advertising production, 90% of the packaging industry, 10% of the surveying and mapping industry, and 98% of other industries. The coating processing methods for paper/plastic composites or plastic/plastic composites still use the instant glue. Wet composite process. That is, when the film is produced, the adhesive is applied on the BOPP film on line and dried and then compounded after drying the device.
In this production process, the in-line coating operation must be completed after the solid resin is dissolved in the liquid organic solvent to synthesize the liquid adhesive; the organic solvent in the liquid adhesive must be volatilized and then reduced to a solid material before the bonding can be completed. This kind of design that depends on phase change to perform construction operations is not only a cumbersome act, but also a self-contradictory between motivation and effect. A large number of facts and experiments have proved that this kind of glue-bonded composite production process is the production process of pollution, sudden fire, wood sticky effect, late adhesive decay, composite material curling, graphic color change, Causes the source of odor migration.
(2) Improper use of raw materials
Adhesives for film coating are available in one-component and two-component adhesives. In order to reduce costs and facilitate operation, except for high-temperature cooking and vacuum-packed composites, most other types of coated films use one-component adhesives.
The main adhesive resin of one-component adhesives is mostly SBS. SBS (styrene-butadiene-styrene block copolymer) is a rubber elastomer material. Although there is a wide range of adhesive properties and a good initial tack effect, it is difficult to completely dry the cured, sub-sensitive adhesive. The synthesis of one-component adhesives depends on aromatic hydrocarbons such as benzene, toluene and other organic solvents. Its flash point is -11.1°C and 4.4°C, respectively. The pure solvent specific evaporation rate is 5 times and 1.95 times the butyl acetate, respectively. The organic solvent swells the BOPP film and increases the thickness and weight of the film by 3.6% and 12.8%, respectively. When the organic solvent is synthesized into an adhesive, the evaporation rate is reduced by more than 15.3%. This data indicates that the drying time given in the film production process is far from ensuring complete volatilization of the organic solvent. On the one hand, Xu Fu caused a large amount of mixed solvent residues in the adhesive on the BOPP film, which reduced the realization of the thermoplastic curability, increased the performance of the sub-sensitive non-dryness, and made the initial viscous strength under the external conditions of hot pressing. Gradually attenuate; at the same time, during the hot press and during the post-cure stage, the movement of the organic solvent molecules mixed in the adhesive increases the swell of the BOPP film, and also causes the cut-off damage to the oil-pigment linkage of the ink and exacerbates. BOPP/ink printing exhibition/composite material's erosion resistance decomposition. On the other hand, the continuous evaporation of organic solvents in the production process (a displacement of a laminator with a width of 800mm is 40m3/min), which increases the concentration of organic solvents in the space around the equipment and is easily generated by the BOPP film material. The electrostatic spark ignites a sudden fire; at the same time, it causes the deterioration of the working conditions in the production environment, allowing the production operator to absorb vapors of benzene-based organic solvents with a content of 40% to 65% from the air, damaging the brain, adrenal glands, liver and blood, and destroying them. Human health.
Two-component adhesives are based on polyester adhesives. By adding a curing agent, the isocyanate is brought into contact with the active hydrogen in the main agent splitter, and a cross-linking reaction occurs in the glue solution to generate a urethane structure and a cross-linked product having a steric conformation with a branched chain structure, having high cohesive force. . However, after the aromatic polyester adhesive is used as a composite packaging material for cooking foods, its main raw material, toluene diisocyanate (TDI), will become aromatic amines after hydrolysis. Aromatic gum migrates through the inner plastic film to food, potentially causing cancer.
(3) Free of technical operation
There are three main types of performance:
The first manifestation is the use of raw materials that are not quantified. There is a lack of scientific and quantitative control over the concentration of adhesives and diluents and the thickness of the adhesive coating.
Randomly change the concentration ratio and the coating thickness specified by the technical department to ensure that the dry basis weight is applied. For the purpose of rapid drying, add more diluent; in order to increase the adhesion, increase the coating thickness. The result is to reduce the relay and increase the swelling of the substrate, destroying the composite effect.
The second manifestation is the free change of equipment operation control parameters. For the normalized equipment parameters such as temperature setting value, air volume setting value, pressure setting value, speed setting value, tension control value, etc., in order to catch up with the production, the method of increasing the temperature and increasing the air volume is used to obtain the adhesive coating. The drying of the layer (temperature increase will only accelerate the coating crust of the glue, which will adversely affect the volatilization of the organic solvent in the middle and deep layers of the coating; the increase of air volume will only lead to a sharp drop in the temperature of the surface of the adhesive coating, so that the drying tunnel The space forms a special microclimate that is hot and cold, and the moisture of the upper hot air rapidly condenses out on the surface of the lower relatively cold adhesive coating to become a kind of disperse phase barrier adhesive and the composite substrate is bonded; or directly improve the machine The operating speed makes the actual use value of the set input data significantly lower (when the operating speed increases from 12m/min to 15m/min in increments of 1m/min, the working pressure drops by It is 8%, 17.5%, and 27%; the decrease in operating temperature is 13%, 27%, and 41%, respectively).
The third manifestation is not good at summing up lessons learned. Can not insist on the basis of raw materials, composites, climate and other objective conditions, the initial setting of the construction program for each batch of processed products first sample test, quality testing, and appropriate adjustments to repeat the test after the batch construction work procedures. According to subjective experience, random mass production can easily result in the loss of targeted construction plans.
(4) Low knowledge content
Lamination is a labor-intensive production process. The fixed processing mode, simple mechanical equipment, and repeated manual operations cover the physics, chemical changes, and inclusive multi-disciplinary knowledge of mechanical, light, chemical, electronics, meteorology, heat, and color. Lamination is actually an integrated product of cutting-edge science and technology and cross-cutting science and technology. It is an initial project of compound technology implementation and composite material manufacturing. Due to a process attributed to postpress processing, linear space is difficult to attract experts and scholars to further study. For a relatively long period of time, it has been developing with a small amount of investment, quick and rapid development, and extensive repetitive operations based on habits and experiences.
3. Innovative technology
(1) The glue-applied wet compounding process has turned to the use of emulsion adhesive (namely known as water-based adhesive)
To solve the pollution and sudden fire caused by the coating process, the solvent-based adhesive for the film has been gradually applied to poly vinyl acetate (PVDC), polyacrylate (PMMA), and other auxiliary materials in the dispersion medium. Under the action of an initiator, an anionic or non-ionic emulsifier, a synthetic polymer suspension type adhesive that is homopolymerized or copolymerized to dissolve in water is replaced by a certain procedure and ratio.
(2) New hot melt adhesive pre-coated film and composite technology have been applied to promote
Through the optimization of EVA, APP, PA and other host materials and formulas. The new type of hot melt adhesive, which is produced by the temperature-controlled synthetic new-type film hot-melt adhesive and the solvent-free melt quantitative coating technology with automatic temperature control, has become a new type of composite material that is pollution-free, non-toxic and safe. Use this new type
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