JP2010175272A - Pulp evaluating method, printing paper evaluating method, and printing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for estimating the production of plate damage in offset printing, and printing paper not bringing about the printing fault caused by the plate damage of offset printing. <P>SOLUTION: In this pulp evaluating method, pulp 5 is processed by a cut flat screen, the number of the solids contained in screen residue is counted by a needle tip and the production of the printing fault caused by the plate damage in the offset printing of the printing paper, which uses the pulp as a raw material, is estimated on the basis of the counted number of the solids. Further, the pulp 5 obtained by beating the printing paper is processed by the cut flat screen, the number of the solids contained in the screen residue is counted by the needle tip and, if the number of the solids is five/1 kg or below of absolute dry pulp, the production of the printing fault caused by the plate damage at the time of offset printing of the printing paper is judged to be within an allowable range. The printing paper is characterized in that the number of the solids is five/1 kg or below of absolute dry pulp. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printing defect evaluation method due to plate scratches occurring when printing paper is printed by an offset printing machine, and a printing paper which does not cause printing defects due to plate scratches when printing by an offset printing machine.

  In recent years, printing technology has made great progress such as high-speed mass printing and automation as well as offset printing and color printing. Offset printing is a system in which ink and dampening water are supplied to a printing plate called a PS plate, and the ink is transferred to paper through a blanket. The PS plate is treated so that the image area is oleophilic and the non-image area is hydrophilic. Ink adheres to the oleophilic image area and water is applied to the hydrophilic non-image area. As a result, the image line portion and the non-image line portion are formed and printed.

  However, a phenomenon of “dirt” in which ink adheres to a non-image area may occur as a printing failure in offset printing. This occurs when a non-image area that is inherently hydrophilic becomes oleophilic. For example, a phenomenon of “greasy sensitization” is known, in which components such as a resin component contained in pulp and a sizing agent applied to the surface of printing paper migrate to and accumulate on a PS plate. On the other hand, the solid matter mixed in the paper is taken up by the blanket, and a “plate scratch” trouble that damages the PS plate may occur. When such a plate damage trouble occurs, it is necessary to stop the printing machine and replace the PS plate, which deteriorates printing workability.

  As a method for quantifying foreign matter contained in pulp, JISP8145 paper and paperboard foreign matter test method (Non-Patent Document 1) and TAPPIUM240 mechanical pulp binding fiber content (Non-Patent Document 2) are known. However, these test methods identify and classify foreign matter according to the appearance and size of the foreign matter and have no direct relationship with offset printing plate scratches. However, it was necessary to confirm the hardness of the foreign material that damages the plate.

JIS Handbook Paper / Pulp 2007 TAPPI practical test method 1988 edition

  In view of the above circumstances, an object of the present invention is to provide a method for predicting the occurrence of plate scratches in offset printing. It is another object of the present invention to provide a printing paper that does not cause printing defects due to plate damage of offset printing.

  The present invention solves the above-described problem, and treats the pulp with a 5-cut flat screen, counts the number of solids contained in the screen residue with a needle tip, and uses the pulp as a raw material according to the number. A pulp evaluation method for predicting the occurrence of printing defects due to plate scratches in offset printing of printing paper. And the pulp which disaggregated the printing paper is processed with a 5-cut flat screen, the number of solids contained in the screen residue is counted with a needle tip, and if the number is 5 / absolutely dry pulp 1 kg or less, the printing A method for evaluating printing paper, in which the occurrence of printing defects due to printing scratches is within an allowable range when the paper is offset printed. In addition, a printing paper in which the pulp from which the printing paper has been disaggregated is treated with a 5-cut flat screen, the number of solids contained in the screen residue is counted with a needle tip, and the number is 5 / one kg or less of dry pulp. It is.

  ADVANTAGE OF THE INVENTION According to this invention, the method of estimating generation | occurrence | production of the printing defect by the plate damage in offset printing can be provided. Furthermore, it is possible to provide a printing paper that does not cause printing defects due to plate damage of offset printing.

It is the figure which showed the pulp blend of the printing paper of Examples 1-4, the comparative examples 1 and 2, and the reference examples 1 and 2, the conditions of a foreign material removal apparatus, and the evaluation result of the number of solid substances and a plate damage.

  As a result of intensive studies on the relationship between foreign matter contained in printing paper and plate damage in offset printing, the present inventors have completed the present invention.

  As a cause of foreign matter contamination of paper, it is mixed in waste paper, chips and raw wood used as pulp raw materials, and components contained in these and chemicals added in pulping and chip making processes of chips, raw wood and waste paper May be scaled and mixed.

  In the paper industry, waste paper is the main raw material from the viewpoint of effective use of resources, and waste paper that is relatively poorly sorted is also used, so removal of foreign matter in waste paper is an important issue. . Foreign materials mixed in waste paper include vinyl and plastic, but sand in soil may also be mixed. Similarly, in chemical pulp and mechanical pulp, soil foreign substances brought from mountain forests may be mixed into raw material chips and raw wood.

  On the other hand, dirt (scale) that adheres and accumulates on manufacturing equipment such as pipes and equipment during the paper / pulp manufacturing process is a pitch component, rosin size, alkyl ketene dimer, sizing agents such as alkenyl succinic anhydride, Contained in paper strength enhancers such as starch, cationized starch and modified polyacrylamide, clay from filler, talc, calcium carbonate, sulfuric acid band, printing ink contained in waste paper, adhesive organic components such as hot melt, and other water It has a complex composition composed of inorganic components such as calcium, barium and iron, and slime from bacteria, sputum and the like.

  In the papermaking industry, neutral papers can use cheap calcium carbonate as a filler, and white paper, high opacity paper can be obtained, and the storability of manufactured paper is good. Its production is increasing. As the proportion of such neutral paper containing calcium carbonate as recovered paper increases, a portion of this calcium carbonate dissolves into the process water in the used paper deinking process, and the recycling of process water is actively promoted. As a result, the calcium concentration in the process water tends to increase compared to the conventional method. In this process, calcium ions in water combine with silicate ions derived from sodium silicate used as a deinking aid or hydrogen peroxide bleaching aid to form a calcium silicate scale. In addition, waste paper treatment in the waste paper deinking process treats not only neutral waste paper but also acidic waste paper at the same time, so the sizing agents and dyes used in acidic paper can be fixed on pulp fibers, yield, drainage A sulfuric acid band added for the purpose of improvement elutes in the process water, which precipitates as aluminum hydroxide as the pH rises, and combines with the silicate ions in the process of crystal growth to produce an aluminum silicate scale. To do.

  On the other hand, in the papermaking process, for example, neutral paper uses calcium carbonate as a filler, so a part of calcium carbonate elutes in the process water and combines with silicate ions in the process water to produce a calcium silicate scale. In addition, when a sulfuric acid band is used for the purpose of improving size fixing and pitch control, the sulfuric acid band is combined with silicate ions in the process of becoming aluminum hydroxide due to the increase in pH. Or generate.

  As described above, as the concentration of calcium carbonate, calcium silicate, and aluminum silicate in process water and service water increases, these may become scales alone, but most of them are combined and grow as scales. Furthermore, it is considered that the aluminum hydroxide produced from the sulfuric acid band has a strong aggregating action and thus agglomerates the scale components and promotes scaling. The problem of scale has become even greater due to the recent increase in the ratio of used paper and the promotion of recycling and recycling of process water. As a countermeasure against this, it is preferable to increase the frequency of line cleaning. However, the line cleaning accompanied by the operation stop brings about a decrease in productivity. Also, the use of a scale inhibitor is conceivable, but not all scale components can be dealt with.

In the present invention, the solid matter that causes plate scratches in offset printing is measured by the following procedure.
1) Collect 500 g of absolutely dry pulp. (When collecting from paper, pulp is obtained by disaggregating the paper with a standard disaggregator specified in JISP8220.)
2) Using a test flat screen, screen residue is collected on black filter paper using a 5-cut plate (slit width 0.13 mm).
3) The screen residue collected on the filter paper is magnified by a factor of 10 using an optical microscope, and the visible foreign matter is pressed with a needle tip (handled needle) and the number of solids is counted. At this time, the foreign matter having elasticity or adhesiveness or the crushed foreign matter held by the tip of the needle is not counted.
4) Calculate the number of solids per kg of dry pulp.
The procedure described above will be described in more detail.
A solid substance having a larger particle diameter is taken by the blanket during printing, and easily reaches the PS plate, and the PS plate is easily damaged. Therefore, it is considered necessary to specify the lower limit of the particle size of the solid matter that causes the plate scratches and to consider the influence (weighting) on the plate scratches due to the size of the particle size. However, when the solids contained in the pulp that has undergone the fine selection process are measured by the above method, the maximum size is about twice the slit width, and no more is seen, so the particle size distribution is narrow. It was. Therefore, it has been found that the influence on the plate damage can be determined by specifying the lower limit of the solid particle diameter and counting the number without intentionally performing the influence (weighting) on the plate damage by the particle size.
Here, the reason why the 5-cut plate (slit width 0.13 mm) is used is that even if a solid material having a small particle size is captured using a plate plate having a smaller slit width, the particle size is small. This is because it has been confirmed in an experiment described later that the solid matter does not affect the plate damage. If the slit width is larger than that of the 5-cut plate, the solid matter is not sufficiently captured, and the solid matter that causes the plate damage cannot be counted.
The reason for not counting elastic or sticky foreign materials or crushed foreign materials by pressing with the needle tip is that there is no risk of elastic or sticky foreign materials damaging the plate even if it reaches the PS plate. This is because the crushed foreign matter is easily crushed when a mechanical force is applied in the subsequent processes.

If solid foreign matter is mixed in the pulp raw material, it is preferable to enhance the cleaning of the chip. However, the chip of the kraft pulp raw material has high moisture content and poor digestibility when washed. Therefore, there are restrictions on the cleaning of the chip.
Conventionally, in order to remove solid foreign matters mixed in pulp, foreign matter removing devices such as screens and cleaners have been used. However, a number of such foreign matter removal devices are installed, such as the manufacturing process of each pulp and the pre-process of the paper machine after blending the pulp, and the operating conditions of each device (screen cleaner rejection rate, cleaner It has been difficult to determine whether the number of prints is effective as a countermeasure against printing scratches. The rejection rate is the ratio of the solid content weight removed as a defective part in the process to the solid content weight entering the process. Simply increasing the rejection rate of the foreign matter removing apparatus becomes a factor of lowering the processing capacity of these apparatuses, and the pulp that can be originally used is washed away, and the yield of the pulp is deteriorated.

  Therefore, by using the evaluation method of the present invention, it is possible to set the optimum operating conditions of the foreign matter removing apparatus in each step. For example, pulp is sampled before and after the foreign matter removing device or the inlet of the paper machine, the number of solids is measured by the evaluation method of the present invention, and the number of solids allowed in each step is set, thereby a screen, a cleaner, etc. It is possible to set the optimum operating conditions of the foreign matter removing apparatus.

  According to the measurement method of the present invention, it is possible to predict the occurrence of printing defects due to plate scratches when the printing paper is put on the printing press, so that it is possible to avoid printing scratch troubles in the printing press. In addition, by applying the measurement method of the present invention in each process of printing paper production, it can be used to identify the cause of occurrence of foreign matter that causes plate damage. Furthermore, it is possible to provide printing paper that does not cause plate damage during offset printing.

  The paper machine used for making the printing paper of the present invention is preferably a double-side dewatering gap former or on-top former, but is not limited thereto. Further, the papermaking pH may be either acidic or neutral.

  As the pulp used for the printing paper of the present invention, the same pulp raw material as that for normal printing paper can be used, and it is not particularly limited. For example, machinery such as kraft pulp (KP), groundwood pulp (GP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), such as softwood bleached kraft pulp, hardwood bleached kraft pulp Pulp, deinked pulp (DIP), etc. can be used.

  Moreover, as a filler mix | blended with the printing paper of this invention, generally used fillers, such as calcium carbonate, talc, clay, kaolin, white carbon, titanium dioxide, urea formalin resin, polystyrene resin, can be used.

  Furthermore, if necessary, saponified rosin sizing agent, rosin emulsion sizing agent, internal sizing agent such as alkyl ketene dimer and alkenyl succinic anhydride, paper strength enhancer such as polyacrylamide, polyvinyl alcohol and cationized starch, and filtration You may contain an aqueous | water-based improving agent, a yield improving agent, dye, a pH adjuster, a pitch control agent, a slime control agent, etc.

Furthermore, as surface treatment agents, starches such as oxidized starch, esterified starch and cationized starch, cellulose compounds such as carboxymethylcellulose and hydroxyethylcellulose, proteins such as casein, synthetic protein and soybean protein, and synthetic products An adhesive such as polyacrylamide or polyvinyl alcohol may be applied. In order to prevent the solid matter causing the plate damage from being taken on the plate, it is preferable to increase the coating amount of the adhesive contained in the surface treatment agent or to use an adhesive having a strong adhesive force.
In addition, synthetic latexes such as a styrene-butadiene copolymer, a methyl methacrylate-butadiene copolymer, and an acrylonitrile-butadiene copolymer can also be used. In addition, surface sizing agents such as anionic polymer compounds such as styrene maleic acid copolymer, styrene acrylic acid copolymer and olefin maleic acid copolymer, and cationic polymer compounds such as styrene polymer, carbonic acid You may apply pigments, such as calcium, clay, and titanium oxide.

  The coating apparatus is not particularly limited, but roll coaters such as two roll size presses, blade metering size presses, rod metalling size presses, gate roll coaters, blade coaters, rod coaters, bar coaters, air knife coaters, curtains. Devices such as coaters and spray coaters are used.

  In the production of the printing paper of the present invention, it is desirable to perform a smoothing process by a calendar device after the surface treatment agent is applied. As such a calendar device, a commonly used calendar device such as a super calendar, a soft calendar, a gloss calendar, a shoe calendar, or the like can be used.

  In this way, the printing paper of the present invention has 5 solids / 1 kg or less of absolutely dry pulp, and the printing paper of the present invention has less plate damage trouble.

  Examples of the present invention will be described below. Unless otherwise specified, parts and% are expressed in terms of solid content or active ingredients.

Example 1
As a pulp, 90% by weight of deinked waste paper pulp (Canadian standard freeness 150ml) and 10% by weight of thermomechanical pulp (Canadian standard freeness 90ml) are mixed. White is used as a filler for 100 parts by weight of pulp. Paper is made by adding 1 part by weight of carbon, 0.4 part by weight of sulfuric acid band, and 1 part by weight of rosin emulsion sizing agent. Then, the coated paper is coated with 0.7 g / m ² of oxidized starch on both sides using a gate roll coater. Manufactured.
In the thermomechanical pulp manufacturing process, dust is removed by a cleaner (primary to quaternary: processed in cascade), and the rejection of the quaternary cleaner is discharged out of the system, and the rejection rate of the cleaner is 1.3% by weight. Yes.
Also, in the paper machine pre-process, the blended pulp passes through the primary fan pump from the seed box, and after dust removal and deaeration by a cleaner (primary to tertiary: cascade processing), passes through the secondary fan pump. The dust is removed by a screen (primary to fourth order: processed in a cascade manner), supplied from the inlet to the wire part of the paper machine, and paper is made. The rejection of the tertiary cleaner and the rejection of the fourth screen are discharged out of the system, and the rejection rate of the cleaner is 0.4% by weight.
The number of solids of the obtained printing paper and the evaluation results of plate scratches during offset printing are shown in FIG.

(Example 2)
A printing paper was produced in the same manner as in Example 1 except that the mixing ratio of the pulp was 80% by weight of deinked waste paper pulp and 20% by weight of thermomechanical pulp. FIG. 1 shows the number of solids on the printing paper and the evaluation results of plate scratches during offset printing.

(Example 3)
A printing paper was produced in the same manner as in Example 1 except that the blending ratio of pulp was 70% by weight of deinked waste paper pulp and 30% by weight of thermomechanical pulp. FIG. 1 shows the number of solids on the printing paper and the evaluation results of plate scratches during offset printing.

Example 4
Printing paper as in Example 3 except that the fourth cleaner is not used in the thermomechanical pulp manufacturing process, the third cleaner reject is discharged outside the system, and the cleaner rejection rate is 1.8% by weight. Manufactured. FIG. 1 shows the number of solids on the printing paper and the evaluation results of plate scratches during offset printing.

(Comparative Example 1)
A printing paper was produced in the same manner as in Example 1 except that the mixing ratio of the pulp was 60% by weight of deinked waste paper pulp and 40% by weight of thermomechanical pulp. FIG. 1 shows the number of solids on the printing paper and the evaluation results of plate scratches during offset printing.
(Reference Example 1)
The number of solids of the printing paper of Comparative Example 1 was evaluated using a 4-cut plate plate (slit width 0.10 mm), and the evaluation results and the evaluation results of plate scratches are shown in FIG.

(Comparative Example 2)
The mixing ratio of the pulp was 60% by weight of deinked waste paper pulp and 40% by weight of thermomechanical pulp, and a quaternary cleaner was added in the pre-process of the paper machine, and the quaternary cleaner reject was discharged outside the system (reject rate 0) Printing paper was produced in the same manner as in Example 1 except that the amount was 3% by weight. FIG. 1 shows the number of solids on the printing paper and the evaluation results of plate scratches during offset printing.
(Reference Example 2)
The number of solids of the printing paper of Comparative Example 2 was evaluated using a 4-cut plate (slit width 0.10 mm), and the evaluation results and the evaluation results of the plate scratches are shown in FIG.

Each evaluation in Examples, Comparative Examples, and Reference Examples was performed as follows.
(Evaluation of the number of solids)
Print paper is disaggregated by the pulp disaggregation method specified in JISP8220, and 500 g of absolutely dry pulp is collected. Using a flat screen for testing, a 5-cut plate plate (slit width 0.15 mm) is used as a screen residue. Is collected on black filter paper. The screen residue collected on the filter paper is pressed with a needle tip (handled needle) for a foreign substance that can be visually recognized using an optical microscope (magnification 10 times), and the number of solid matters alone is counted. (Pressing with a needle tip does not count elastic or sticky foreign matter or crushed foreign matter). Then, the number of solids per 1 kg of absolutely dry pulp was determined. The same sample was measured twice, and the average value was defined as the number of solids.
(Evaluation of plate damage)
After printing 20,000 sheets on an offset sheet-fed machine and printing an unnecessary image line due to scratches on the PS plate, it was judged as plate scratches and the number of the prints was evaluated.

In the result shown in FIG. 1, it can be seen that the solid matter measurement method according to the present invention is effective as an evaluation method for printing plate scratches, as can be seen by comparing the number of solids and evaluation of plate scratches. It can also be seen that printing scratches are suppressed in the printing paper in which the number of solids is 5 / one kg or less of absolutely dry pulp. Here, it can be seen from the results of the comparative example and the reference example that the number of plate scratches is not affected even when a 5-cut plate plate or a 4-cut plate plate is used.

Claims (3)

  The pulp is treated with a 5-cut flat screen, the number of solids contained in the screen residue is counted with the needle tip, and printing defects due to plate scratches in offset printing of printing paper that uses the pulp as a raw material are counted according to the number. Predicted pulp evaluation method.   The pulp from which the printing paper is disaggregated is treated with a 5-cut flat screen, and the number of solids contained in the screen residue is counted with a needle tip. If the number is 5 / one kg or less of dry pulp, the printing paper is A printing paper evaluation method that determines that the occurrence of printing defects due to plate damage is within an allowable range when offset printing is performed. A printing paper in which the pulp from which the printing paper has been disaggregated is treated with a 5-cut flat screen, the number of solids contained in the screen residue is counted with a needle tip, and the number is 5 / one kg or less of absolutely dry pulp.

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