Experience in the use of digital printing press paper
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Digital printing equipment is generally divided into color digital printing machines and black and white digital printing machines; according to the type of paper, it can be divided into single-page paper and continuous paper digital printing machines, but regardless of the classification, each category has different brands. Digital presses with different speeds and different functions. As far as the daily use of digital printing paper is concerned, any digital printing equipment will have a set of paper precautions that conform to its structure, performance and operation. If it is necessary to be precise to each machine and each type of paper, then How many versions of paper should have precautions for how many digital presses? Therefore, the articles listed in this article are only some of the precautions for paper use, which will be explained in the following five aspects.
First, the use of plain paper
Before using digital printing equipment, you should first familiarize yourself with the paper manual to understand the paper requirements, which standards are applicable to the applicable paper, and what are the standard compliance parameters for each standard. Generally, the paper that meets the standard needs to meet the standards of paper type, weight, filling and slurry. This requires first-time inspection of the paper. The inspection indicators include the following three points.
(1) Paper type. Through hardness, electrical resistance, double-sided characteristics, water content, ash content (excluding other components other than pulp), packaging and storage conditions, post-press curvature, fixing (ability to permanently absorb ink), paper feeding 9 items Indicators to check if the paper type meets the requirements of the digital press.
(2) Paper quantification. There is usually a quantitative range of paper available for the press in the manual. Using lighter (or thinner) paper may cause the paper to tear, the paper hole to rupture, or misloading. Using a heavier (or thicker) piece of paper may cause misfeeds (not smooth paper feed) or stains, falling off the feeder, etc., because the paper is too hard. To avoid these problems, be sure to use paper that meets the quantitative requirements.
(3) Paper loading and slurry. If the amount ratio of the filler is too high, the pulp composition is too low, and even if the paper amount meets the specifications, the hardness of the paper is not appropriate. This can also cause the printer to jam, incorrectly fold or wrinkle.
Therefore, papers that meet the applicable range of digital presses should be used in strict accordance with the paper manual of the digital press.
Second, the use of recycled paper
If you want to use recycled paper, be sure to check the print quality and folding function in advance. These inspections are done for each box of recycled paper. After checking the above items, contact the paper manufacturer to inquire about whether the recycled paper maintains consistent paper characteristics.
Note the following points when using recycled paper.
(1) Since the recycled paper is easily damp, please store it with a moisture-proof film.
(2) Recycled paper produces a large amount of paper ash. These paper dusts can adhere to the rollers, sensors, paper feed channels, and drum components, which can cause various problems. Therefore, always clean the paper ash.
(3) Since the recycled paper is easily damp and bent, and the hardness is low, the paper often has a paper feed error.
(4) Recycled paper that is too curved may cause paper feed or stacking errors.
(5) Recycled paper of low mechanical strength may cause damage to the paper feed hole, incorrect folding or wrinkling.
(6) Non-smooth recycled paper will reduce print quality.
(7) If a pile of paper contains recycled paper of different nature, the print quality may vary.
Third, the use of special paper
The paper mill will continue to develop and sell a variety of new special papers. In order to use these special papers, the product must be tested in advance. The precautions for the use of several common special papers are as follows.
(1) label paper
The label paper must be stored in an environment with a temperature of 15 ° C to 32 ° C and a humidity of 40% to 70% and must be used within one year after production. After shipment, the label paper must be moisture-proof film or similar packaging as early as possible to prevent moisture. The print quality of the tangent portion may be reduced. Therefore, it is necessary to avoid printing on the tangent portion. For the sake of printing accuracy, a 2mm border should be left. If the quality and thickness of the label and back sheet are different, fixing heating may cause the paper to curl. To avoid this, the label and back page must be printed with static electricity so that the paper does not become noticeably curled when heated. If the label paper stack is too high, the binder of the bottom paper may be squeezed out due to the stack weight. Therefore, consult the paper manufacturer's maximum stack height.
(2) holed paper
Perforated bumps or burrs may have a negative impact on print quality. Therefore, be sure to use only paper that has no bumps and burrs. Avoid printing near perforations when designing the print format. For perforation reasons, a margin of approximately 3.5 mm should be left for each perforation.
(3) Sealed envelope paper
Uneven adhesive can cause misfeeds or negatively affect print quality. Therefore, use of print media that has such problems should be avoided. Important data should not be printed near the adhesive and should be at least 3.5mm. If you stack too many sealed envelopes together, stacking pressure can cause the media to stick together, so consult the manufacturer for the maximum stackable height. Partially sealed envelopes have a shorter storage time than normal media, which also requires consultation with the manufacturer about the shelf life and storage conditions.
(4) Mail-type media (postcard type)
The two sides (possibly one side) of the postal paper medium (postcard type) are coated with a binder. Due to the strict requirements for the pre-printing environment (such as ink type and color quantity) of such media, please consult the paper manufacturer before purchasing. Each side of the print media is coated with a pressure sensitive adhesive. Therefore, when the surface coated with the adhesive is printed, the adhesion may fail due to insufficient bonding strength. To prevent this type of problem, you should avoid printing the symmetrical position of the fold bond when designing the page.
(5) colored paper
Color paper has a smoother surface than normal paper because colorants and fixing agents (resins) penetrate into the paper fibers. Therefore, the toner does not easily penetrate into the paper fibers, and the toner fixing strength is low. When the adsorption force between the fixing agent and the toner is low, the toner fixing strength is particularly low. If you must use colored paper, carefully check the printing conditions and preprint.
(6) embossed paper
Embossed paper with company logos and other marks is called embossed paper. Inconsistent or uneven thickness of each part of the paper may cause paper jams or negatively affect the print quality. The print conditions must be carefully checked and pre-printed.
(7) coated paper
Paper coated with titanium oxide, kaolin, clay or calcium carbonate is used as art paper, coated paper, light coated paper or fully coated paper. Generally, the coated paper has a low toner fixing strength and a low print quality. When printing coated paper, consult the paper manufacturer in advance to carefully confirm the printing conditions and preprint.
(8) Carbonless copy paper
The carbonless copy paper consists of three parts that can sense the pressure. On a contact press, carbonless copy paper enables simultaneous printing. The pressure sensing medium can deliver the printed content to the second and third portions. When using a non-contact press, all three parts need to be printed separately and then stapled together. Carbonless copy paper is thin in each part, prone to paper feed or stacking errors, or melts the paper's pressure-sensing medium due to temperature factors, so spare parts replacement and maintenance conditions should be evaluated before mass printing of carbonless copy paper.
Fourth, avoid paper
The inapplicability of paper consists of a number of factors that will reduce print quality or cause some unusual paper feed errors. It is best not to use the following types of paper:
(1) Paper that is incorrectly folded;
(2) torn paper or paper having irregular holes;
(3) paper with missing corners;
(4) curved, wrinkled, undulating or sunken paper;
(5) paper placed obliquely;
(6) Paper (such as wax, metal sheet, glue, resin, etc.) with small pieces of paper and external objects;
(7) Special paper with glue or tape.
Fifth, the storage of paper
In addition to the use of paper type, paper quantification and other digital printing machine performance, daily paper storage box can not be ignored, if improper storage, it will cause paper deformation, and will directly affect the effect of printed products, or cause printing failure .
First the paper cannot be placed directly on the floor. Placement directly on the floor can cause the paper to get wet. Place the paper tray horizontally on a flat shelf, flat shelf or tow table. To prevent paper distortion, do not stack too much paper on top of each other. The stacking height must not exceed 1 meter. In order to prevent the paper from drying or getting wet, it is best to place the paper in a sealed box at 10 ° C ~ 30 ° C and maintain a relative humidity of 40% to 50% (the highest drying temperature is 29 ° C).
When opening the box and found that the paper does not have waterproof storage conditions, place the paper tray in a suitable environment with waterproof measures. The recommended environment is a temperature of 15 ° C ~ 25 ° C, relative humidity of 30% ~ 70%. Paper can't be placed for too long (more than 6 months) even in an environment that is resistant to moisture and moisture. Once the tray is opened, the paper must be wrapped with a waterproof film to prevent it from becoming too dry or damp. Paper should not be subjected to sudden temperature changes to prevent it from becoming too dry or damp. It is best to ship to the place of use beforehand and buffer it for a while.
These are some of the basic daily experience of digital printing press paper, and I hope to be helpful to digital printing practitioners.