——Solve the problem of low surface strength. An effective method for paper lint-free in offset printing. Offset-printed paper with low surface strength often causes problems such as lint-free, peeling, and powder-removal during the printing process, which increases the labor intensity of the operator. , It also increases the downtime cleaning time, eventually there will be poor quality, low efficiency and other issues, operators often feel very headache when printing this paper. Judging from the paper quality situation in recent years, such problems as peeling and de-powdering have been relatively reduced, but the phenomenon of paper loss still exists.
At present, the determination of the strength of various types of coated paper and offset paper used by printing houses in the country is mainly measured by the critical “pile†speed measured by the paper adaptability tester as a test measurement data. Coated paper grade is divided into O grade, A grade and B grade three, offset paper grade is divided into special number (overpressure), 1 (super, universal pressure) and 2 (common pressure) three. The greater the value of the “pickup†speed tested, the higher the surface strength of the paper, and the less likely it is to lose hair; conversely, the smaller the value of the “pile†speed, the lower the surface strength of the paper, and the easier it is to lose hair.
From the paper on the paper strength grades of the coated paper and offset paper currently used by the printing industry, the relevant departments:
Coated paper: The grades of grade O and different gram weights are of the best quality. The “pile†speed is maintained at 200 cm/s. Grades A and B are graded. As the weight of the paper increases, the “pile†speed increases. The reduction.
Offset paper; special number, No. 1 and No. 2 offset paper, the measured paper range is 60-120g/m2, and the “pulling†speed is between 110-60cm/s, that is, as the weight of the paper increases, "The speed is reduced. Extra-thick offset paper is the best strength.
From the comparison of the development of the papermaking industry in China's papermaking industry and other countries in the world, due to the constraints of raw materials, papermaking equipment, and process technology, the paper's surface strength is still somewhat different from that of imported paper. For comparable indicators, such as “pulling†speed, most imported papers are above 500cm/s, while domestic papers are generally below 200cm/s, with a difference of 1-2 times.
In the actual printing production process, in addition to the low surface strength (pile speed) of the paper, the paper is also affected by the adhesion of the ink to the paper, the adhesion of the ink to the paper due to the high-speed operation of the roller, and the high-speed operation of the roller. The force of ink on the stripping force of the paper and the suction force of the blanket on the paper are three kinds of constraints. Among the many forces mentioned above, some are constant factors and some are variable factors. The absorptivity of the blanket to the paper is basically the same, and the surface strength of the paper, due to the limitations of the type and price of the printed product, prescribes in advance the type and weight of the paper, and how the operator of the offset press has low surface strength. The exquisite products printed on the paper can only be solved by both the adhesion of the ink and the peeling tension. From the following four aspects to explore how to solve the paper surface due to the low strength of the printed products to bring adverse effects, as well as solutions.
First, the size of the stripping tension The size of the stripping tension depends on three aspects, namely: the viscosity of the ink, the printing speed and the printing pressure. The size of the ink adhesion also depends on the viscosity of the ink. Therefore, to sum up the above points, the variable factors include the viscosity value of the ink, the printing speed, and the printing pressure. This makes it possible to use the paper with low surface strength to print the key to the operation of a good product.
Second, reduce the viscosity of the ink If you want to reduce the viscosity of the ink, you can add in the ink to reduce the viscosity of the auxiliary agent, the general printing plant generally adopts No. 6 varnish or to (withdraw) adhesive and other methods to reduce the ink viscosity. After testing, generally, for every 1% of No. 6 varnish added to the ink, the tack value will decrease by about 0.2-0.3, and the fluidity will increase by about 0.5%. If only to reduce the viscosity, the effect is relatively small. In general, in order to reduce the viscosity of the ink, we should take appropriate amount of (adhesion) agent to improve the "pulling" speed of the paper.
Taking Beijing 80g/m2 offset paper and printing No. 8139 yellow ink as an example, when 3-4% of the release agent was added, the "pile" speed was increased by 126% compared with that before use. It can be seen that, after the original surface strength of the paper is added to the ink (withdraw) adhesive, the "pulling" speed value can be increased by several times. Therefore, for paper with severe hair loss, measures should be taken to add (remove) adhesives to the ink. However, it must be noted that the amount of adding (removing) adhesives should be strictly controlled and cannot exceed 5%, otherwise there will be problems such as greasy dirt, unclear dots, and slow drying.
Third, on the change in printing speed Because the printing speed is proportional to the peeling tension, so the faster the printing speed, the easier it is to lose hair. However, reducing the printing speed is equivalent to reducing the production efficiency. In general, the machine speed should not be reduced too much. This can only be a transitional method.
Fourth, on the change of the printing pressure In theory, the printing pressure is reduced, the stripping tension is also reduced, it seems to be good for paper lint, but in actual printing is not the case. In many cases when printing paper that is easy to lose hair, if the pressure is increased by 0.05 mm, the number of times of washing the blanket is reduced, and the ink of the printed product is firmer than the original. Although the undergrowth was still seen on the blanket, the effect was much better. This is probably due to the fact that the surface of the paper, which is generally susceptible to linting, is relatively sparse. Increasing the pressure increases the ink transfer rate.
In short, if you want to use a paper with low surface strength to print excellent products that satisfy your customers, the most effective method at present is to add an appropriate amount of desorption agent to the ink to solve the printing process caused by the low surface strength of the paper. Loss of hair, peeling, de-powdering and other phenomena. ("China Packaging News")
At present, the determination of the strength of various types of coated paper and offset paper used by printing houses in the country is mainly measured by the critical “pile†speed measured by the paper adaptability tester as a test measurement data. Coated paper grade is divided into O grade, A grade and B grade three, offset paper grade is divided into special number (overpressure), 1 (super, universal pressure) and 2 (common pressure) three. The greater the value of the “pickup†speed tested, the higher the surface strength of the paper, and the less likely it is to lose hair; conversely, the smaller the value of the “pile†speed, the lower the surface strength of the paper, and the easier it is to lose hair.
From the paper on the paper strength grades of the coated paper and offset paper currently used by the printing industry, the relevant departments:
Coated paper: The grades of grade O and different gram weights are of the best quality. The “pile†speed is maintained at 200 cm/s. Grades A and B are graded. As the weight of the paper increases, the “pile†speed increases. The reduction.
Offset paper; special number, No. 1 and No. 2 offset paper, the measured paper range is 60-120g/m2, and the “pulling†speed is between 110-60cm/s, that is, as the weight of the paper increases, "The speed is reduced. Extra-thick offset paper is the best strength.
From the comparison of the development of the papermaking industry in China's papermaking industry and other countries in the world, due to the constraints of raw materials, papermaking equipment, and process technology, the paper's surface strength is still somewhat different from that of imported paper. For comparable indicators, such as “pulling†speed, most imported papers are above 500cm/s, while domestic papers are generally below 200cm/s, with a difference of 1-2 times.
In the actual printing production process, in addition to the low surface strength (pile speed) of the paper, the paper is also affected by the adhesion of the ink to the paper, the adhesion of the ink to the paper due to the high-speed operation of the roller, and the high-speed operation of the roller. The force of ink on the stripping force of the paper and the suction force of the blanket on the paper are three kinds of constraints. Among the many forces mentioned above, some are constant factors and some are variable factors. The absorptivity of the blanket to the paper is basically the same, and the surface strength of the paper, due to the limitations of the type and price of the printed product, prescribes in advance the type and weight of the paper, and how the operator of the offset press has low surface strength. The exquisite products printed on the paper can only be solved by both the adhesion of the ink and the peeling tension. From the following four aspects to explore how to solve the paper surface due to the low strength of the printed products to bring adverse effects, as well as solutions.
First, the size of the stripping tension The size of the stripping tension depends on three aspects, namely: the viscosity of the ink, the printing speed and the printing pressure. The size of the ink adhesion also depends on the viscosity of the ink. Therefore, to sum up the above points, the variable factors include the viscosity value of the ink, the printing speed, and the printing pressure. This makes it possible to use the paper with low surface strength to print the key to the operation of a good product.
Second, reduce the viscosity of the ink If you want to reduce the viscosity of the ink, you can add in the ink to reduce the viscosity of the auxiliary agent, the general printing plant generally adopts No. 6 varnish or to (withdraw) adhesive and other methods to reduce the ink viscosity. After testing, generally, for every 1% of No. 6 varnish added to the ink, the tack value will decrease by about 0.2-0.3, and the fluidity will increase by about 0.5%. If only to reduce the viscosity, the effect is relatively small. In general, in order to reduce the viscosity of the ink, we should take appropriate amount of (adhesion) agent to improve the "pulling" speed of the paper.
Taking Beijing 80g/m2 offset paper and printing No. 8139 yellow ink as an example, when 3-4% of the release agent was added, the "pile" speed was increased by 126% compared with that before use. It can be seen that, after the original surface strength of the paper is added to the ink (withdraw) adhesive, the "pulling" speed value can be increased by several times. Therefore, for paper with severe hair loss, measures should be taken to add (remove) adhesives to the ink. However, it must be noted that the amount of adding (removing) adhesives should be strictly controlled and cannot exceed 5%, otherwise there will be problems such as greasy dirt, unclear dots, and slow drying.
Third, on the change in printing speed Because the printing speed is proportional to the peeling tension, so the faster the printing speed, the easier it is to lose hair. However, reducing the printing speed is equivalent to reducing the production efficiency. In general, the machine speed should not be reduced too much. This can only be a transitional method.
Fourth, on the change of the printing pressure In theory, the printing pressure is reduced, the stripping tension is also reduced, it seems to be good for paper lint, but in actual printing is not the case. In many cases when printing paper that is easy to lose hair, if the pressure is increased by 0.05 mm, the number of times of washing the blanket is reduced, and the ink of the printed product is firmer than the original. Although the undergrowth was still seen on the blanket, the effect was much better. This is probably due to the fact that the surface of the paper, which is generally susceptible to linting, is relatively sparse. Increasing the pressure increases the ink transfer rate.
In short, if you want to use a paper with low surface strength to print excellent products that satisfy your customers, the most effective method at present is to add an appropriate amount of desorption agent to the ink to solve the printing process caused by the low surface strength of the paper. Loss of hair, peeling, de-powdering and other phenomena. ("China Packaging News")
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