company news about Corrugated base paper purchase instructions

Corrugated base paper purchasing notice
In order to attract more consumers' attention, more and more corrugated box manufacturers choose offset printing or pre-printing (flexographic printing, gravure) to make corrugated boxes. However, due to the purchase of "sick" paper, the increase in the waste rate of corrugated boxes caused by the downtime of printing equipment and the increase in the rate of customer complaints, corrugated box manufacturers have paid a heavy price. Then, what are the paper diseases of the face paper (mainly gray-backed whiteboard paper, coated kraft cardboard, etc.) used to make corrugated boxes? Influence 7 In this article, the author analyzes the common causes of corrugated base paper one by one, hoping to help corrugated box manufacturers to identify the pros and cons when purchasing base paper.

 

Diagnosis of common diseases of corrugated paper

 

 

Symptom 1: Static electricity

cause:

(1) In the process of paper making, the content of rosin is too much, and the electrolyte such as aluminum sulfate and the filler such as kaolin are less, and high-voltage static electricity is generated after drying and high-temperature and high-pressure treatment.

(2) During the printing process, if the paper itself contains less water, static electricity will also be generated in the process of mutual friction.

(3) Paper piles up in the paper library. And the time is short, and the moisture in the paper does not have time to reach equilibrium.

(4) The temperature of the paper (related to the ambient temperature of the paper library) is quite different from the temperature of the printing workshop. cause the paper to shrink. Generates physical static electricity.

harm:

After the paper is electrostatically charged, it will be difficult to separate, and during the offset printing process, multiple sheets of paper will be formed into the printing machine at the same time. In web printing, they repel each other due to same-sex charges. There will be drift of printed products, inaccurate overprinting, uneven delivery of paper, or difficulty in rewinding paper.

In addition, paper with static electricity is also easy to absorb dust and paper scraps in the air, making it stick to the printed matter and directly contaminate the printed matter. Sparks are generated when static electricity accumulates to a certain strength. Plant a fire hazard. In winter when dry. Such accidents are especially prone to occur.

 

 

Symptom 2: Hair loss. powder

cause:

(1) Improper slurry ratio or filling amount weakens the fiber binding force.

(2) The beating degree does not meet the requirements.

(3) The fluctuation of the paper leaf on the Internet is large, and the evenness is not good.

(4) The pressure set by the press drum is not enough.

(5) There are attachments on the surface of the dryer.

(6) The temperature of the drying section is too high.

(7) The paper cutter is dusty. The cutter is too dull.

(8) The moisture content of the finished paper is too low.

harm:

Paper wool and filler block the printing plate, affecting the normal production of the printing press.

 

 

Symptom 3: Fluctuation of paper basis weight and uneven basis weight of paper web

The fluctuation of the basis weight of the paper includes the basis weight fluctuation in the longitudinal direction of the paper and the basis weight fluctuation in the direction of the paper web. These fluctuations can be divided into periodic fluctuations and irregular fluctuations.

The main reasons for cyclical fluctuations:

(1) Because the conveying system of the paper stock to the headbox is subject to periodic

vibration.

(2) Vibration of the rotor screen or slurry pump in front of the headbox.

The main reasons for irregular fluctuations:

(1) The production process is unreasonable or caused by improper operation.

(2) The change of the original pulp concentration causes the concentration of the finished pulp to fluctuate.

(3) The pulping operation of the beater is improper, resulting in poor mixing of the pulp tank.

(4) The air mixed in the pulp resists the paper stock.

(5) The speed of the paper machine has changed.

The non-uniform basis weight in the direction of the paper web refers to the inconsistent basis weight in the direction of the width of the paper machine, that is, the half thickness of the paper web. Half thin or one thick. A thin.

main reason:

(1) The stock is in the entire width of the headbox. The flow velocity at each point is not

Consistent.

(2) The opening of the sizing lip is uneven or the lip is defective.

(3) The edge setter causes the paper material on the net to be corrugated.

(4) There are "ditch beams" in the longitudinal direction of the copper mesh.

harm:

Uneven weight of the paper web will cause uneven printing pressure, resulting in uneven inking and inconsistent dot restoration.

In addition to the above-mentioned hazards, the uneven quantification in the longitudinal direction may also cause the printing cylinder and the impression cylinder to collide with each other, shortening the life of the machine and the printing plate.

When carton manufacturers purchase base paper. A simple way to check whether the paper weight is uniform can be used: observe whether the wet water line of the paper is neat. If the wet water line is neat, it means that the paper weight is relatively uniform. If the wet water line is seriously uneven, it means that the paper weight change may be large. Generally, the quantitative part of the elongation of the wet water line is higher. The quantification of the part where the wet water line is shortened is low.

 

 

Symptom 4: Dust-spotted hard lumps

(1) Dust: refers to the surface exposed on cardboard or paper. Various impurities that can be seen at any angle and have a distinct color difference from other parts. Divided into black dust and other dust.

(2) Spots: Spots are not much different from dust. It is mainly due to the inconsistent glossiness and reflections on the paper surface. According to the characteristics of the spots can be divided into wet spots. Cylinder spot. Calendered dark spots, paste and bubble spots, filler spots, paint spots and bright and white spots. The spots on the paper are poorly inked. The ink is not easy to absorb the printing color or the writing is inconsistent with other parts.

(3) Hard block: Hard block refers to the hard blocky material and coarse-grained material that occasionally appears on the paper, such as wood knot grass knot, pulp block, raw meal block, etc. The hard block is very harmful to printing, it will crush the printing plate and blanket, and even cause serious damage to the printing press. Large, hard lumps on the paper can cause serious printing failures.

 

 

Symptom 5: Poor evenness

main reason:

(1) In the beating process, the pulp of the long fibers is insufficiently beaten, and the pulp is cut less during the beating process, so that the pulp in the fibers is intertwined into a group.

(2) The vibration of the head box and the net of the paper machine, and the insufficient dispersion of the fibers will also lead to poor uniformity.

(3) During the printing process, the paper with poor evenness will produce stress concentration under the tension of the printing machine, especially the roll paper printing machine, and the phenomenon of high paper breakage rate will occur.

An easy way to check for poor formation is to point the paper at a strong light source. evenness

Defective paper will appear flocculated clumps.

 

 

Symptom 6: Cracks

A rip is a crack or break in the middle or edge of the paper. These cracks or broken 1:3 are easy to expand or be pulled off during the printing process, resulting in paper breakage and downtime. affect production efficiency. Increase paper loss.

 

 

Symptom 7: Inconsistent hues

Whiteness and tone inconsistencies appear in the same batch of paper or even the same color

The phenomenon.

This phenomenon often occurs in some small and medium-sized papermaking enterprises. Because the whiteness of the paper is different. There is a clear difference between the light and dark of the printed pattern. Customers can easily refuse.

 

 

Symptom 8: Ruffles

Ruffle refers to the edge of the paper. In particular, the paper loses its original straight state in the longitudinal direction. By observing the side of the paper, it is easy to find that the side of the paper with ruffles has irregular honeycomb-like pores. When printing on ruffled paper. Overprinting and wrinkles will occur. Fine fold phenomenon. Paper with severe ruffles cannot be machine printed. The above 8 kinds of paper diseases are all problems that corrugated box manufacturers may encounter in the process of purchasing base paper. If you can understand the causes and identification methods of paper defects, you can identify them in the procurement process and reduce unnecessary losses.