The difference between offset paper and pure paper
Offset paper, formerly known as "Dowling Paper", is mainly used for printing high-grade color printed matter by lithographic (offset) printing machines or other printing machines, and is suitable for printing monochrome or multicolor book covers, characters, inserts, pictorial, maps, posters, color trademarks and various packaging products.
Offset paper is divided into special number, 1 number and No.2 and No.3 according to the proportion of pulp, which has high strength and good printability. There are single-sided and double-sided, and there are two grades of super calendering and ordinary calendering. Offset printing is a kind of advanced printing paper for books and periodicals, which requires high contrast, expansion rate and surface strength, and the pH value should be close to neutral or weakly alkaline so as not to affect the printing paper.
Offset paper has small flexibility, uniform ink absorption, good smoothness, compact and opaque texture, good whiteness and strong water resistance. Conjunctival offset printing ink and good quality lead ink should be selected. The viscosity of ink should not be too high, otherwise there will be powder removal and galling. Also to prevent the back from getting dirty, generally use antifouling agent, dusting or lining paper.
Pure paper is refined from 100% imported high-quality wood fiber, and the product has all the natural characteristics of paper with advanced environmental protection concept. The paper is ultra-light and ultra-thick, economical and practical. Light paper is beige, and pure paper is cream. Its smooth and dull surface makes the printing more stereoscopic. Books printed with it have soft paper, mild color, ultra-low reflectivity and natural atmosphere, which will bring you a brand-new feeling.
The concept of pure paper
This product is made of 100% imported high-quality wood fiber, which has all the natural characteristics of paper with advanced environmental protection concept. The paper is ultra-light and ultra-thick, economical and practical. Light paper is beige, and pure paper is cream. Its smooth and dull surface makes the printing more stereoscopic. Books printed with it have soft paper, mild color, ultra-low reflectivity and natural atmosphere, which will bring you a brand-new feeling.
The main methods of the paper
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The production of general printing paper is divided into two basic processes: pulping and papermaking. Pulping is to dissociate plant fiber raw materials into natural pulp or bleached pulp by mechanical method, chemical method or a combination of the two. Papermaking is to combine pulp fibers suspended in water into sheets that meet various requirements through various processes.
Paper mills generally need to store enough raw materials for 4 ~ 6 months, so that the raw materials can naturally ferment during storage, which is beneficial to pulping and ensures the continuous production of paper mills. Raw materials such as reed, wheat straw and wood are cut into pieces (used to produce chemical pulp) or wood chips (used to produce ground wood pulp) in the material preparation section, and then small pieces of raw materials are put into a digester, added with chemical liquid, and steamed with steam to make the raw materials into pulp, or the wood chips are sent to a wood mill to be ground, or they can be ground after a certain degree of cooking. Then wash the pulp with plenty of clean water, and remove coarse chips, knots, stones and sand from the pulp through screening and purification. According to the requirements of paper types, the pulp is bleached to the required whiteness with bleaching agent, and then beaten with beating equipment. Then various auxiliary materials, such as fillers, sizing agents, sizing agents, etc., are added to the pulp, and then purified and screened. Finally, the paper pulp is sent to a paper machine, filtered for moisture in the wire section, squeezed and dehydrated, dried in a dryer, calendered and coiled, and then cut, rewound or cut to produce rolled paper and plain paper. If the production is to produce coated printing paper, it needs to be dried in the middle or produced into roll paper and then coated.
In addition to the above-mentioned basic procedures, it also includes some auxiliary procedures, such as the preparation of cooking liquid, the preparation of bleaching liquid, the boiling of rubber compound and the recovery of chemicals and heat energy from cooking waste liquid and waste gas.
Papermaking process
1: Cut down trees to make materials
2. Cut into suitable lengths.
Step 3: Peel the bark.
Step 4: Cut into pieces
5: Cut into thin slices
6. Concentrate the flakes and transport them to the paper mill.
7. Pulping with liquid medicine and steam.
8: Rinse with liquid medicine
9: Removing impurities
10: bleached pulp
1 1: Add chemicals to the pulp.
12: drain water with net.
13 field on the felt to absorb water.
14: high temperature drying moisture
15: Calendering with calender
16: made into paper roll.
Main surface characteristics of paper
① Sizing degree (water resistance): It is very important for writing paper that the surface of paper can prevent ink from permeating and diffusing during writing. Dip a duckbill pen in special ink and draw a line on the paper, which is expressed by the maximum width (mm) of the non-diffusion and non-permeability line. (2) Smoothness: Under a certain degree of vacuum, a certain volume of air passes through the air.
mica-paper
Under a certain pressure, the time required for the gap between the sample surface and the glass surface is expressed in seconds. ③ Surface strength: In order to prevent paper from falling off and pasting, offset printing paper requires good surface strength. The number of wax rod stages from pressing paper with wax rod to drawing fiber can also be expressed by measuring drawing speed with printing instrument. What drawing paper and tracing paper tested was its friction resistance, and it was a test of paper surface tissue bonding strength.
In addition to the above performance; There are many special performance test requirements in other technical documents. For example, the dielectric constant, dielectric strength, dielectric loss, burning speed, thermal conductivity of thermal insulation paper, resistance coefficient of filter paper to fluid and rejection coefficient of filter material, softness and water absorption of toilet paper are all important performance indexes of quality, which need to be tested according to specified standards to evaluate its performance.
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