Application of kraft paper in the printing and packaging industry

Kraft paper as a common material in the printing and packaging industry, then you know how to use kraft paper correctly?

The use of kraft paper
In the printing and packaging industry, kraft paper is commonly used for printing financial statement covers, envelopes, commodity packaging, document bags, information bags, hand bags, file boxes, file bags, etc.

Specification of kraft paper
Commonly used kraft paper has various specifications such as 60g/m2, 70g/m2, 80g/m2, 100g/m2, 120g/m2, 150g/m2 and even 250~450g/m2.

Characteristics of kraft paper
Advantages: Kraft paper has the advantages of good toughness, hard and strong texture, not easily torn and broken, and resistant to wear and tear.
Disadvantages: kraft paper paper surface roughness, easy to appear on the buckle under the pick, falling hair, de powder phenomenon, whiteness, flatness, smoothness is poor.

The use of kraft paper skills
① Hanging and adjusting wet treatment: the first step to the surface unevenness and has been broken paper removed, the second step will be the paper surface impurities, paper ash clean, hanging drying treatment, so that the temperature and humidity of kraft paper and offset printing workshop temperature and humidity to maintain consistent. Kraft paper after hanging drying moisture treatment, placed on top of the paper stack pressed paper splint, with large stones, iron plate compaction, to avoid paper fluffy not solid. Doing so can effectively avoid the emergence of kraft paper due to uneven moisture content appears on the phenomenon of buckling under the pick.

② choose a good model: because of the 80g/m2 thicker kraft paper, in the paper delivery nozzle often can not absorb the paper, so when the kraft paper thickness ≥ 80g/m, it is best not to use small four or eight open offset printing machine printing. In addition, due to the small paper width, easy to double or multi-sheet failure, or paper skewed in the delivery of paperboard. And with the folio offset press or full-opening offset press printing ≥ 80g / m of kraft paper, the effect will be better.

③ adjust offset printing machine paper delivery system: the thickness of the paper is larger is easy to cause rolling stop accidents, so before starting the printing machine must be before the punch control, skew control, double control, and other electrical devices to adjust the appropriate, to prevent the kraft paper more than one roll bad machine. Should be adjusted to the size of the suction nozzle suction volume, paper suction nozzle and paper feed suction nozzle to use the diameter and thickness are larger rubber ring.

④ keep the printing cylinder and rubber cylinder center distance unchanged: adjust the center distance of the impression cylinder and rubber cylinder and keep the center distance unchanged, when printing 250 ~ 450g / m kraft paper, this center distance can be enlarged by 0.2 ~ 0.4mm. kraft paper surface roughness, smoothness is poor, the tightness of the paper is much less than copperplate paper, offset paper, therefore, printing kraft paper, but also correspondingly increase the printing pressure. When printing kraft paper thickness ≥ 400g / m, the printing plate cylinder and rubber cylinder gap of 3.95mm, rubber cylinder and impression cylinder gap adjustment for 3.40mm, the total package lining of the printing plate cylinder for 0.65 ~ 0.75mm, the total package lining of the rubber cylinder for 3.15 ~ 3.35mm. If the printing paper from thick to thin, should be drawn from the printing plate lining in the reduced thickness of the Package lining, plus to the rubber cylinder package lining; if the paper from thin to thick, should be drawn from the rubber cylinder to increase the thickness of the package lining, plus to the printing plate cylinder package lining.

⑤ kraft paper surface rough, loose, easy to powder, hair, so when printing to diligently scrub the rubber cylinder and printing plate cylinder, to avoid paper hair, paper powder adhered to the rubber cylinder and printing plate cylinder and affect the ink transfer, resulting in graphics off the plate, lack of pen broken row. If it is encountered in the summer when the monochrome printing, kraft paper hair, powder serious problems, can be printed before the overlay layer of water, which can effectively reduce the paper hair, powder phenomenon, so that the paper is more flat.

Post time: Nov-01-2022