51. How does the polymer dissolve and dissolve?
The dissolution of the polymer occurs in two stages: swelling first and then dissolving. Because there are a lot of gaps between the segments of each molecule of the polymer, the solvent molecules can penetrate when in contact with the solvent. “The volume of the polymer is increased first, and the chain is pushed open so that the gap between the segments increases. The solvent continues. Infiltration allows more molecules to be solvated and the distance between the segments becomes larger and larger so that the entire long chain of the macromolecule is separated from each other into the solvent and the dissolution process is completed.â€
52. What is the role of solvents in plastics and compounding?
Solvents are an important part of gravure inks and flexographic inks, and are indispensable materials for plastic film composite adhesives.
The solvent has the ability to dissolve substances and volatilize itself, and its volatilization rate is an important factor that determines the ink layer drying of the volatile ink and affects the printing quality. If the solvent volatilizes slowly, the print reproducibility is poor. However, if the solvent does not completely evaporate during rotary printing, the ink layer is likely to stick during printing. On the other hand, if the solvent in the ink volatilizes too quickly during the printing process, the ink will fade and the roller will stick. Therefore, the choice of solvent is very important.
53, there are several commonly used solvents for gravure and flexo printing?
Commonly used solvents for gravure and flexo printing are:
Hydrocarbons: toluene, etc.
Esters: methyl acetate, ethyl acetate, n-butyl acetate and the like.
Ketones: acetone, methyl ethyl ketone and so on.
Alcohols: isopropanol, isobutanol, n-butanol, ethanol and the like.
54, isopropyl alcohol and its performance?
Isopropanol (CH3)2CHOH, colorless and transparent body. It smells like ethanol. The specific gravity is 0.7851 (20/4°)°C. The melting point is 117.3°C. Distilled at a boiling point of 78.10°C. Can dissolve many organic compounds and some inorganics. Can burn. Ethanol evaporation and air mixing can form explosives with an explosion limit of 3.5-10.0% (volume). It is very versatile. As a thinner for water-based plastic inks. In summer it can be used as a mixed solvent for polyamide gravure inks.
55, what is ethanol and its performance?
Ethanol CH3CH2OH, commonly known as alcohol. Colorless, transparent, volatile and flammable liquids. There is the smell of wine. The specific gravity is 0.7893 (20/4°). The melting point is 117.3°C. The boiling point of 78.4 °C. Soluble in water, methanol, ether and chloroform. Hygroscopicity. Forms an azeotropic mixture with water. Normal alcohol contains 95.57% (by weight) of ethanol and distills at 78.10°C. Can dissolve many organic compounds and some inorganics. Can burn. Ethanol evaporation and air mixing can form explosives with an explosion limit of 3.5 to 18.0% (volume). It is very versatile. As a thinner for water-based plastic inks. In summer it can be used as a mixed solvent for polyamide gravure inks.
56, what is butanol? What is the use of plastic printing?
Butanol C4H9OH, there are four isomers. Important butanol and isobutanol are important. Can be used for plastic gravure ink slow drying agent.
(1) n-butanol CH3(CH2)2CH2OH. The colorless liquid has a wine odor. The specific gravity is 0.8098 (20/4°). Boiling point 117.7°. Freezing point - 89.0°. Soluble in water, miscible with ethanol and ether. Vapors and air form an explosive mixture with an explosion limit of 3.7-10.2% by volume and are used as solvents and dehydrating agents.
(2) Isobutanol (CH3)2CHCH2OH, colorless transparent liquid. There is a special smell. The specific gravity is 0.806 (15°C). Melting point -108 °C. The boiling point of 107 °C. Soluble in water, ethanol and acetic acid. Vapors and air form an explosive mixture with an explosion limit of 2.4% (volume). For solvents, plasticizers and antioxidants.
57. What is the solvent of methyl ethyl ketone commonly used in the solvent formula of gravure ink? How is it characteristic?
Methyl ethyl ketone is an abbreviation for methyl(ethyl)ethyl ketone CH3COC2H5. Also known as butanone. Colorless flammable liquid. Poisonous, can cause blindness after drinking. The specific gravity is 0.7915 (20/4°) and the melting point is 97.8°C. The boiling point is 64.65 °C. Compatible with water and various organic solvents.
58, plastic printing ink solvent how to choose?
Plastic printing inks usually need to consider the following factors: (1) the speed of the printing press; (2) the structure of the drying system; (3) the characteristics of the printing material; (4) the indoor temperature and relative humidity; (5) the type of printing plate; The solvent cannot corrode with the printing plate; (6) It should have good dissolving power, free from any mechanical impurities and free acids, alkalis, and moisture; it has a good evaporation rate (commonly known as dryness). These several requirements are the key indicators for selecting ink solvents. (7) The solvent cannot react chemically with the components of the ink; (8) The odor is small, the toxicity is low (the most ideal solvent is non-toxic and odorless), the volatile gas must meet the requirements of environmental protection, and it should be used for food packaging. Actually non-toxic grade; printed products must not have the odor of residual solvents. (9) Storage stability, no decomposition, no moisture absorption; (10) Low price and abundant supply.
59, what are the factors that affect the volatilization of ink?
(1) Mixing ratio of solvents. The volatilization rate of the mixed solvent is restricted by the solvent molecules, and its volatilization rate is not the average of their volatilization rates.
(2) Effect of resin. The volatilization of the solvent in the ink is relatively complex. When the resin dissolves in a dry solvent, the molecules of the two substances bind tightly to each other (the action of the solvent). At this time, the volatilization rate of the solvent is lower than the volatilization rate of the solvent itself. A certain viscosity liquid ink volatilizes the attached solvent during the drying process, the resin content increases, and the solvent volatilization rate also slows down.
(3) The condition of pigment particles. When ink is added, the rate of volatilization of the solvent is greatly reduced when pigments, fillers, and other materials are added. The finer the particles of the pigment, the larger the surface area and the slower the evaporation rate of the solvent.
(4) Influence of ambient temperature and humidity. The higher the room temperature in the printing shop, the faster the evaporation rate of the solvent, and vice versa. Indoor air circulates and the solvent evaporates quickly. If the interior is relatively closed, the solvent evaporates slowly. So high-speed gravure or flexo presses are equipped with heating and exhaust. The conditional plastic printing factory should be equipped with a solvent recovery device, which not only solves the problem of drying of the solvent volatile ink layer, but also solves the problem of sewage discharge, which is beneficial to the physical and mental health of employees.
63, ink viscosity and viscosity are different?
Viscosity is also called stickiness or internal friction. Fluid (including liquids and gases) has a property that hinders its relative flow inside. When a liquid is agitated, its flow rate is proportional to the amount used, and the force used (shear stress) = constant X shear rate.
The size of the viscosity is mainly determined by the composition of the ink. If the viscosity of the binder in the ink is large, the viscosity of the ink is also large; in addition, the solvent content is large and the viscosity is small; the pigment content is large and the viscosity is large. The higher the temperature in the workshop, the lower the twist and so on.
The viscosity of ink is also called stickiness. Refers to the ink in the printing process, between the ink and the ink roller, between the ink roller and the printing plate, between the printing plate and the object to be printed, at the moment of separation of the ink film layer, the ink molecule produces a resistance ink layer The force of separation is called the adhesion of the ink.
The viscosity of the ink is low. From the printing paper, the linking material will permeate too much into the paper and the print will lack luster, which will affect the fixing of the print. The thin layer formed from printing and printing is so thin that the color and gloss of the printed product are thin. If the viscosity of the ink is too high. Paper printing and printing will cause poor transmission of ink, ink inequality, and even the phenomenon of block printing plate cable. Therefore, the viscosity of the ink must be moderate. Paper printing ink with oil viscosity adjustment. Need to increase the viscosity of the ink when adding No. 0 varnish, need to reduce viscosity when adding No. 6 varnish. Plastic film gravure printing and flexo printing, color plastic film fast-drying thinning agent and slow-drying thinning agent to adjust ink viscosity. The viscosity is related to the printing speed. The higher the printing speed, the lower the viscosity. Flexographic inks are more viscous than gravure inks. Gravure ink pigment content 10-30%, viscosity (poise) 0.5-10; soft ink pigment content 10-40%, viscosity (poise) 1-100.
64. What are the contents of conventional inks?
(1) the color of the ink; (2) the viscosity of the ink; (3) the absolute viscosity of the ink, measured in poise or centipoise as the viscosity of the fluid. From the comparison of the flow time of the falling-viscosity fluid in the capillary viscometer; (4) the adhesiveness of the ink; (5) the dryness of the ink; (6) the coloring power of the ink; (7) the fineness of the ink; 8) The degree of ink flow; (9) The acid and alkali resistance of the ink. Resistance to ethanol.
65, plastic ink is how to classify and name it?
There are many kinds of plastic inks, and there are no uniform regulations for its classification and nomenclature. There are generally the following:
(1) According to the printing plate type, plastic ink is divided into: plastic letterpress printing ink. Plastic gravure inks, plastic flexo inks, and plastic screen (shim) inks.
(2) According to the plastic ink drying form can be divided into: oxidation drying ink, volatile drying ink and double liquid melon-type composite ink.
(3) According to the use of the connecting material can be divided into: such as polyamide type, acrylic type and rubber type ink.
(4) According to the different solvents used can be divided into. Mixed solvent type, water type, benzene type, etc.
66, why different types of plastic ink can not be mixed?
Plastic inks are generally based on the speed of the printing press, the characteristics of the material being printed, and the process used. For example, plastic printing and plastic flexographic printing, although the same as the embossing, but the former printing speed is very slow, the need to oxidize the conjunctival ink The latter has a fast printing speed and requires volatile drying inks, which must not be used interchangeably. For another example, plastic flexographic printing and plastic gravure printing are rotary printing, and the printing speeds are similar. Volatile inks are used. However, the former is a resin plate, taking into account whether the solvent in the ink has a corrosive effect on the plate. Whereas the latter is a metal plate, there is no need to consider the effect of the solvent on the plate. In addition, polyethylene, polypropylene, polyester, cellophane, etc. in common packaging materials are all plastic transparent films, but their respective printability is not the same, and corresponding inks are also needed.
67, plastic gravure ink should have what printability?
Plastic film gravure printing ink is the thinnest, the least viscous, like spray paint, contains many solvents, has a good fluidity and transferability of colloidal fluid. Ink manufacturers are designed based on the following conditions.
(1) Gravure printing machine printing speed is fast, the domestic satellite gravure rotary printing press and the gravure gravure printing machine's printing speed is 65-80M/MIN, the introduction of the gravure rotary printing machine can print up to 150-200M/MIN. In addition, the concave depth of the gravure is generally 25-35 um, and the deepest is 40 um. The ink transfer rate on the plate is generally 35-45%, and the thickness of the ink layer on the substrate is 9-20UM. With such rapid printing and plate indentation depths, the oxidized conjunctiva alone cannot achieve fast drying. Therefore, a volatile drying ink is used. It is filled and coated with intaglio patterns by its own fluidity and adhesion. in. The drying of the printing ink layer is accomplished by volatilization of the solvent contained in the ink.
(2) Polyethylene and polypropylene are the most used for plastic packaging materials. This kind of film basically belongs to the non-polar plastic, the surface tension is low, acid and alkali resistant, the ink layer only sticks with the film surface. In addition, additives (white oil, anti-static agents, etc.) in the plastic raw materials are continuously oozing out to the surface, affecting the print fastness. Therefore, the plastic oil must have good affinity.
(3) Plastic gravure inks should have good weatherability. Our country is vast in size and the climate in the north and south is very different. General gravure ink drying temperature 20-30 °C. Above 30°C, the drying rate increases with volatilization, and below 20°C, evaporation and drying slow down. Relative humidity of 65-75% is the most suitable. Therefore, there should be a corresponding solvent to adjust the drying speed.
(4) Gravure inks should have vivid hue, high saturation, good transparency or opacity, strong attachment fastness, and bright enough to accommodate multi-color, high-speed, continuous printing requirements.
68, what kind of gravure ink should have?
There are many types of plastic gravure inks, except that they are divided into "printing inks" and "printing inks", and the corresponding inks are produced according to the different substrates used. This means that for a plastic film, there is a special ink. For example: Japan's Toyo Oil
The dissolution of the polymer occurs in two stages: swelling first and then dissolving. Because there are a lot of gaps between the segments of each molecule of the polymer, the solvent molecules can penetrate when in contact with the solvent. “The volume of the polymer is increased first, and the chain is pushed open so that the gap between the segments increases. The solvent continues. Infiltration allows more molecules to be solvated and the distance between the segments becomes larger and larger so that the entire long chain of the macromolecule is separated from each other into the solvent and the dissolution process is completed.â€
52. What is the role of solvents in plastics and compounding?
Solvents are an important part of gravure inks and flexographic inks, and are indispensable materials for plastic film composite adhesives.
The solvent has the ability to dissolve substances and volatilize itself, and its volatilization rate is an important factor that determines the ink layer drying of the volatile ink and affects the printing quality. If the solvent volatilizes slowly, the print reproducibility is poor. However, if the solvent does not completely evaporate during rotary printing, the ink layer is likely to stick during printing. On the other hand, if the solvent in the ink volatilizes too quickly during the printing process, the ink will fade and the roller will stick. Therefore, the choice of solvent is very important.
53, there are several commonly used solvents for gravure and flexo printing?
Commonly used solvents for gravure and flexo printing are:
Hydrocarbons: toluene, etc.
Esters: methyl acetate, ethyl acetate, n-butyl acetate and the like.
Ketones: acetone, methyl ethyl ketone and so on.
Alcohols: isopropanol, isobutanol, n-butanol, ethanol and the like.
54, isopropyl alcohol and its performance?
Isopropanol (CH3)2CHOH, colorless and transparent body. It smells like ethanol. The specific gravity is 0.7851 (20/4°)°C. The melting point is 117.3°C. Distilled at a boiling point of 78.10°C. Can dissolve many organic compounds and some inorganics. Can burn. Ethanol evaporation and air mixing can form explosives with an explosion limit of 3.5-10.0% (volume). It is very versatile. As a thinner for water-based plastic inks. In summer it can be used as a mixed solvent for polyamide gravure inks.
55, what is ethanol and its performance?
Ethanol CH3CH2OH, commonly known as alcohol. Colorless, transparent, volatile and flammable liquids. There is the smell of wine. The specific gravity is 0.7893 (20/4°). The melting point is 117.3°C. The boiling point of 78.4 °C. Soluble in water, methanol, ether and chloroform. Hygroscopicity. Forms an azeotropic mixture with water. Normal alcohol contains 95.57% (by weight) of ethanol and distills at 78.10°C. Can dissolve many organic compounds and some inorganics. Can burn. Ethanol evaporation and air mixing can form explosives with an explosion limit of 3.5 to 18.0% (volume). It is very versatile. As a thinner for water-based plastic inks. In summer it can be used as a mixed solvent for polyamide gravure inks.
56, what is butanol? What is the use of plastic printing?
Butanol C4H9OH, there are four isomers. Important butanol and isobutanol are important. Can be used for plastic gravure ink slow drying agent.
(1) n-butanol CH3(CH2)2CH2OH. The colorless liquid has a wine odor. The specific gravity is 0.8098 (20/4°). Boiling point 117.7°. Freezing point - 89.0°. Soluble in water, miscible with ethanol and ether. Vapors and air form an explosive mixture with an explosion limit of 3.7-10.2% by volume and are used as solvents and dehydrating agents.
(2) Isobutanol (CH3)2CHCH2OH, colorless transparent liquid. There is a special smell. The specific gravity is 0.806 (15°C). Melting point -108 °C. The boiling point of 107 °C. Soluble in water, ethanol and acetic acid. Vapors and air form an explosive mixture with an explosion limit of 2.4% (volume). For solvents, plasticizers and antioxidants.
57. What is the solvent of methyl ethyl ketone commonly used in the solvent formula of gravure ink? How is it characteristic?
Methyl ethyl ketone is an abbreviation for methyl(ethyl)ethyl ketone CH3COC2H5. Also known as butanone. Colorless flammable liquid. Poisonous, can cause blindness after drinking. The specific gravity is 0.7915 (20/4°) and the melting point is 97.8°C. The boiling point is 64.65 °C. Compatible with water and various organic solvents.
58, plastic printing ink solvent how to choose?
Plastic printing inks usually need to consider the following factors: (1) the speed of the printing press; (2) the structure of the drying system; (3) the characteristics of the printing material; (4) the indoor temperature and relative humidity; (5) the type of printing plate; The solvent cannot corrode with the printing plate; (6) It should have good dissolving power, free from any mechanical impurities and free acids, alkalis, and moisture; it has a good evaporation rate (commonly known as dryness). These several requirements are the key indicators for selecting ink solvents. (7) The solvent cannot react chemically with the components of the ink; (8) The odor is small, the toxicity is low (the most ideal solvent is non-toxic and odorless), the volatile gas must meet the requirements of environmental protection, and it should be used for food packaging. Actually non-toxic grade; printed products must not have the odor of residual solvents. (9) Storage stability, no decomposition, no moisture absorption; (10) Low price and abundant supply.
59, what are the factors that affect the volatilization of ink?
(1) Mixing ratio of solvents. The volatilization rate of the mixed solvent is restricted by the solvent molecules, and its volatilization rate is not the average of their volatilization rates.
(2) Effect of resin. The volatilization of the solvent in the ink is relatively complex. When the resin dissolves in a dry solvent, the molecules of the two substances bind tightly to each other (the action of the solvent). At this time, the volatilization rate of the solvent is lower than the volatilization rate of the solvent itself. A certain viscosity liquid ink volatilizes the attached solvent during the drying process, the resin content increases, and the solvent volatilization rate also slows down.
(3) The condition of pigment particles. When ink is added, the rate of volatilization of the solvent is greatly reduced when pigments, fillers, and other materials are added. The finer the particles of the pigment, the larger the surface area and the slower the evaporation rate of the solvent.
(4) Influence of ambient temperature and humidity. The higher the room temperature in the printing shop, the faster the evaporation rate of the solvent, and vice versa. Indoor air circulates and the solvent evaporates quickly. If the interior is relatively closed, the solvent evaporates slowly. So high-speed gravure or flexo presses are equipped with heating and exhaust. The conditional plastic printing factory should be equipped with a solvent recovery device, which not only solves the problem of drying of the solvent volatile ink layer, but also solves the problem of sewage discharge, which is beneficial to the physical and mental health of employees.
63, ink viscosity and viscosity are different?
Viscosity is also called stickiness or internal friction. Fluid (including liquids and gases) has a property that hinders its relative flow inside. When a liquid is agitated, its flow rate is proportional to the amount used, and the force used (shear stress) = constant X shear rate.
The size of the viscosity is mainly determined by the composition of the ink. If the viscosity of the binder in the ink is large, the viscosity of the ink is also large; in addition, the solvent content is large and the viscosity is small; the pigment content is large and the viscosity is large. The higher the temperature in the workshop, the lower the twist and so on.
The viscosity of ink is also called stickiness. Refers to the ink in the printing process, between the ink and the ink roller, between the ink roller and the printing plate, between the printing plate and the object to be printed, at the moment of separation of the ink film layer, the ink molecule produces a resistance ink layer The force of separation is called the adhesion of the ink.
The viscosity of the ink is low. From the printing paper, the linking material will permeate too much into the paper and the print will lack luster, which will affect the fixing of the print. The thin layer formed from printing and printing is so thin that the color and gloss of the printed product are thin. If the viscosity of the ink is too high. Paper printing and printing will cause poor transmission of ink, ink inequality, and even the phenomenon of block printing plate cable. Therefore, the viscosity of the ink must be moderate. Paper printing ink with oil viscosity adjustment. Need to increase the viscosity of the ink when adding No. 0 varnish, need to reduce viscosity when adding No. 6 varnish. Plastic film gravure printing and flexo printing, color plastic film fast-drying thinning agent and slow-drying thinning agent to adjust ink viscosity. The viscosity is related to the printing speed. The higher the printing speed, the lower the viscosity. Flexographic inks are more viscous than gravure inks. Gravure ink pigment content 10-30%, viscosity (poise) 0.5-10; soft ink pigment content 10-40%, viscosity (poise) 1-100.
64. What are the contents of conventional inks?
(1) the color of the ink; (2) the viscosity of the ink; (3) the absolute viscosity of the ink, measured in poise or centipoise as the viscosity of the fluid. From the comparison of the flow time of the falling-viscosity fluid in the capillary viscometer; (4) the adhesiveness of the ink; (5) the dryness of the ink; (6) the coloring power of the ink; (7) the fineness of the ink; 8) The degree of ink flow; (9) The acid and alkali resistance of the ink. Resistance to ethanol.
65, plastic ink is how to classify and name it?
There are many kinds of plastic inks, and there are no uniform regulations for its classification and nomenclature. There are generally the following:
(1) According to the printing plate type, plastic ink is divided into: plastic letterpress printing ink. Plastic gravure inks, plastic flexo inks, and plastic screen (shim) inks.
(2) According to the plastic ink drying form can be divided into: oxidation drying ink, volatile drying ink and double liquid melon-type composite ink.
(3) According to the use of the connecting material can be divided into: such as polyamide type, acrylic type and rubber type ink.
(4) According to the different solvents used can be divided into. Mixed solvent type, water type, benzene type, etc.
66, why different types of plastic ink can not be mixed?
Plastic inks are generally based on the speed of the printing press, the characteristics of the material being printed, and the process used. For example, plastic printing and plastic flexographic printing, although the same as the embossing, but the former printing speed is very slow, the need to oxidize the conjunctival ink The latter has a fast printing speed and requires volatile drying inks, which must not be used interchangeably. For another example, plastic flexographic printing and plastic gravure printing are rotary printing, and the printing speeds are similar. Volatile inks are used. However, the former is a resin plate, taking into account whether the solvent in the ink has a corrosive effect on the plate. Whereas the latter is a metal plate, there is no need to consider the effect of the solvent on the plate. In addition, polyethylene, polypropylene, polyester, cellophane, etc. in common packaging materials are all plastic transparent films, but their respective printability is not the same, and corresponding inks are also needed.
67, plastic gravure ink should have what printability?
Plastic film gravure printing ink is the thinnest, the least viscous, like spray paint, contains many solvents, has a good fluidity and transferability of colloidal fluid. Ink manufacturers are designed based on the following conditions.
(1) Gravure printing machine printing speed is fast, the domestic satellite gravure rotary printing press and the gravure gravure printing machine's printing speed is 65-80M/MIN, the introduction of the gravure rotary printing machine can print up to 150-200M/MIN. In addition, the concave depth of the gravure is generally 25-35 um, and the deepest is 40 um. The ink transfer rate on the plate is generally 35-45%, and the thickness of the ink layer on the substrate is 9-20UM. With such rapid printing and plate indentation depths, the oxidized conjunctiva alone cannot achieve fast drying. Therefore, a volatile drying ink is used. It is filled and coated with intaglio patterns by its own fluidity and adhesion. in. The drying of the printing ink layer is accomplished by volatilization of the solvent contained in the ink.
(2) Polyethylene and polypropylene are the most used for plastic packaging materials. This kind of film basically belongs to the non-polar plastic, the surface tension is low, acid and alkali resistant, the ink layer only sticks with the film surface. In addition, additives (white oil, anti-static agents, etc.) in the plastic raw materials are continuously oozing out to the surface, affecting the print fastness. Therefore, the plastic oil must have good affinity.
(3) Plastic gravure inks should have good weatherability. Our country is vast in size and the climate in the north and south is very different. General gravure ink drying temperature 20-30 °C. Above 30°C, the drying rate increases with volatilization, and below 20°C, evaporation and drying slow down. Relative humidity of 65-75% is the most suitable. Therefore, there should be a corresponding solvent to adjust the drying speed.
(4) Gravure inks should have vivid hue, high saturation, good transparency or opacity, strong attachment fastness, and bright enough to accommodate multi-color, high-speed, continuous printing requirements.
68, what kind of gravure ink should have?
There are many types of plastic gravure inks, except that they are divided into "printing inks" and "printing inks", and the corresponding inks are produced according to the different substrates used. This means that for a plastic film, there is a special ink. For example: Japan's Toyo Oil
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