Q&A about printing paper (208-225)

208. Which are mainly chemical pulp? What are the performance characteristics?
A: Papers based on chemical pulps include advanced non-coated papers, advanced coated papers, and advanced specialty papers. These papers contain little or no mechanical pulp and contain 5% to 25% fillers. Pulp includes softwood pulp and hardwood pulp. This paper is characterized by its high tensile strength, whiteness and good storage properties.

209. Which paper does the advanced non-coated paper include? How to classify?
A: The advanced non-coated paper can be divided into three types according to the coating (sizing) method: low-coated paper, first painted with a sizing device, and standard advanced coated paper, and then coated after pre-coating. Fine art paper needs three coats. According to the quantitative divided into offset printing paper and lightweight paper.

210. What are the performance characteristics of offset printing paper?
A: Offset printing paper is referred to as offset paper, and its quantitative range is very wide, from 40 to 300 g/m2. ISO brightness> 80%, high surface strength, easy to lose hair, powder off is its biggest feature, multi-layer filling technology also gives high filler content of offset paper brings a good printing effect.

211. What are the performance characteristics of lightweight paper?
A: Lightweight paper refers to low-quantity offset paper with a quantification range of 25 to 40 g/m2. The most representative is dictionary paper.

212. Advanced coated paper including what paper?
A: Advanced coated paper includes standard high-grade coated paper, WFC paper, low-coated paper, and art coated paper (copper paper).

213. What are the performance characteristics of standard advanced coated paper? What is the main application range?
A: The standard high-grade coated paper has a basis weight of 90 to 170 g/m2, an ISO brightness of 80% to 96%, a fiber ratio of more than 90% is a chemical pulp, a total pigment content of 30% to 45%, and calcium carbonate. White clay is the most commonly used pigment. The standard high-grade coated paper is mainly used for printing advertisements, books, boutique newspapers and high-quality catalogs as well as magazines and direct mail advertisements.

214. What are the performance characteristics of low-coated paper? What is the main application range?
Answer: The quantity of low-coated paper is generally 55 to 135 g/m2, the coating volume is 3 to 14 g/m2·face, and the total loading is 20% to 35%. Its scope of use is narrower than that of standard high-grade coated paper, and it is generally used for books, dictionaries, timetables, and booklets.

215. What are the performance characteristics of coated paper? What is the main application range?
Answer: The quantitative range of coated paper is 100-230g/m2, and the coating amount is 20-40g/m2. Mainly used for printing atlases, calendars, and manuals.

216. Advanced specialty paper including what paper?
A: Advanced specialty paper includes copy paper, digital printing paper, and continuous recording paper.

217. What are the performance characteristics of copy paper?
A: The most important property of copy paper is that it can pass through the copier smoothly and has good dimensional stability. When copying, it must not be curled or pleated, and it cannot afford static electricity.

218. What are the performance characteristics of digital printing paper?
A: Digital printing paper is a rapidly growing type of paper that uses chemical pulp as the main raw material. It is mainly non-coated paper, but advanced coated paper is used more and more. Most of these papers are used for short-run printing, image scanning, and database printing.

219. What are the performance characteristics of continuous printing paper?
A: The continuous printing paper is used for the list and setting table printing, the quantitative is 40 ~ 90g/m2, the paper has high tensile strength and good dimensional stability, the surface is clean, the filler content is 5% ~ 25%.

220. What is paper disease? What are the common paper diseases?
A: Any paper defect that is not covered by the paper quality technical requirements is called paper disease, including those that cannot be seen and cannot be touched. Some performance defects that can only be known through testing or printing, such as brittle, print-through, and hair loss , powder, etc.; also includes various defects and defects that can be seen or felt directly on the surface of the paper sheet, such as dust, spots, pleats, holes, curtains, rigid blocks, embossing, pulp, etc. .

221. What is the quantitative unevenness of paper?
A: There are two aspects of uneven paper quantification. On the one hand, fluctuations in paper quantification refer to quantitative fluctuations in the direction of the paper machine (longitudinal direction of the paper), including periodic instantaneous fluctuations and irregular quantitative fluctuations; The aspect is the unevenness of the paper web.

222. What is the reason for the periodic fluctuations in the paper's quantitative periodicity?
A: The periodic transient fluctuations are caused by the periodic vibration of the feed system of the paper headbox, the vibration of the front wing screen or the pulp pump of the headbox, and sometimes due to the bending of the homogenizer roll in the headbox or Unreasonable opening. This fluctuation has little effect on the larger amount of paper, but it is more detrimental to the use of thin paper.

223. What is the cause of irregular fluctuations in the amount of paper produced?
A: The specific reasons include: fluctuations in pulp consistency caused by changes in the consistency of the pulp; improper pulping operations in the beater and poor mixing in the slurry pool; the air mixed in the pulp "sticks" the paper stock; the speed of the paper machine changes.

224. What is the uneven web weight? What is the specific reason?
A: The uneven ration of paper web refers to the quantitative inconsistency along the width direction of the paper machine. That is, half of the web thickness is thin or one thin. The main reasons for the uneven ration of the paper web are: the flow speed of the paper material at various points in the entire width of the headbox is inconsistent; the opening degree of the sizing lip is uneven or the lip is defective; the edger causes the web paper Material "folding"; copper network vertical "ditch."

225. How to judge whether the web ration is even?
A: The easiest way to judge whether the paper web is even or not is to observe the unevenness of the wet line. The wet line refers to the boundary between the bright light that can be seen when the paper material is dehydrated online and the light that cannot see water. If the wetlines are flush, the paper banners must be more evenly quantified; if the wetlines are severely misaligned, the banner rations of the paper are likely to differ significantly. Generally, the site of elongation of the wet water line is high, and the site of the shortening of the wet water line is low.
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