What kind of paper is used for general teaching materials, and the density is so high? Why do textbooks use this paper to make books so heavy?

Classification of paper by purpose and quality (continental classification)

It is usually divided into six categories according to the purpose: printing paper and cardboard; Paper and paperboard for writing, painting and reproduction; Wrapping paper and cardboard; Paper and paperboard for life, hygiene and decoration; Technical paper and paperboard; Processing paper base paper.

Printing paper and paperboard

1, coated with printing paper and paperboard

There are offset printing coated paper, offset printing coated base paper, coated stamp paper, coated stamp base paper, coated white board, low quantitative offset printing coated paper, embossed offset printing coated paper, cast coated paper, cast coated white board base paper, matte printing coated paper, coated cardboard, coated box board and low quantitative gravure coated paper.

2. uncoated printing paper and paperboard

There are newsprint, Bible paper, map paper, ocean map, offset book paper, letterpress printing paper, textbook paper for primary and middle school students, offset printing paper, single-sided offset printing paper, book cover paper, sea newspaper, white cardboard, rice cardboard, gravure paper, securities paper, stamp paper, political paper, braille printing paper, playing card paper, weekly newspaper, thin embossed paper and single-sided book cover.

Paper and paperboard for culture, art and daily life

1, writing paper

There are typing paper, drawing paper, Xuan paper, writing paper, single-sided writing paper (glossy paper), drawing paper, watercolor paper, sketch paper, charcoal drawing paper, double red paper, striped writing paper, ledger paper, edge paper, historical paper, leather drawing paper, water writing paper, oil painting blank paper, blotting paper and plum red paper.

2. Copy paper

There are tracing paper, stylus wax paper base paper, dry electrostatic copy paper, blueprint base paper, dry diazo photosensitive paper, carbon-free copy paper, typing copy paper, double-low map base paper, electrostatic copy tracing paper, typing wax paper base paper, carbon-free copy paper, typing wax paper base paper, thermal paper, electrostatic plate-making paper and carbon-free copy paper.

3. Toilet paper

There are sanitary napkins, wrinkled toilet paper, diaper paper, thin non-woven fabric, rat killing paper, plaster paper, medical cotton paper, water-soluble medical paper, cotton paper and wet paper towels.

4, household paper

There are shoemaking cardboard, woven base paper, paper insoles, black photographic cardboard, tablecloth paper, cloth substitute paper, kitchen paper, art paper, mirror cleaning paper and petticoat paper.

5. Decorative paper

There are decal paper, decal paper backing paper, wax paper, decorative base paper, wax paper base paper, wallpaper base paper, plastic-coated wallpaper, wrinkled base paper, adhesive base paper, plastic decorative panel, gypsum board, base paper, facial paper, ceramic membrane decal paper, ceramic membrane decal paper, metal decal paper, enamel decal paper,

Wrapping paper and cardboard

1, universal wrapping paper

There are bag paper, kraft paper, egg paper, aluminum foil lining paper, needle-wrapped paper, translucent paper, striped kraft paper, film protection base paper, match paper, neutral packaging paper, extensible bag paper, tissue packaging paper, ordinary packaging paper, striped packaging paper, agricultural packaging paper, soap packaging paper, corrugated tire packaging paper, paddle residue packaging paper, aluminum packaging paper, packaging base paper and vinylon cloth paper composite packaging materials. Recycled kraft paper, recycled cement bag paper, waterproof bag paper, phosphate fertilizer bag paper, recycled corrugated bag paper, wrapping paper, kraft paper board, gray lining paper, blue coated sandpaper, composite corrugated base paper, machine-made white paper, empty aluminized base paper, vacuum aluminized paper, and film lining paper.

2. Special wrapping paper

There are industrial parchment, superfine parchment, industrial parchment base paper, superfine parchment, neutral paraffin base paper, cellophane, striped asphalt base paper, striped asphalt base paper, moisture-proof drainage base paper, vapor-phase moisture-proof base paper, vapor-phase rust-proof base paper, black opaque paper, sodium benzoate rust-proof paper, neutral plastic wax moisture-proof wrapping paper and asphalt-lined paper.

3, food packaging paper

There are food parchment, food sheepskin base paper, candy packaging base paper, popsicle wrapping paper, imitation parchment, common food wrapping paper, oil-proof paper, liquid food packaging composite material, extruded candy wrapping paper, cake fresh-keeping oxygen-proof composite packaging material and cake fresh-keeping deoxidizer bag paper.

4, packaging cardboard

There are single-sided white board, thick board, yellow board, neutral board, box board, kraft board, corrugated base paper, standard board, suitcase board, tea board, match box board, match box board, double-sided broken board and green broken board.

Technical paper and paperboard

1. Paper and board for testing and information recording

There are non-perforated paper tape for information processing, perforated electronic newspaper, computer continuous recording format base paper, industrial automation instrument recording paper, electrocardiogram paper, information processing continuous format paper, single-page telex paper, perforated cardboard, wet sonar recording paper, spark recording base paper, red translucent force sensing recording paper and white translucent force sensing recording paper. Deep well water-resistant recording paper, thermal fax paper, deep well polyester card paper, deep well pressure recording paper, electroencephalogram paper, low-voltage electrical sensitive paper, oscillographic recording paper, electro-acoustic paper, force sensitive recording paper, meteorological recording paper, ribbon paper for instrument calibration, thermal recording paper, ECG base paper, spark fax paper, spark relay fax paper, pH test paper, hydrogen sulfide analysis paper and carbon paper.

2, filter paper and cardboard

There are quantitative filter paper, qualitative filter paper, filter paper, non-heat sealing tea filter paper, chromatographic filter paper, industrial filter paper, engine oil filter paper base paper, J- 140 engine oil filter paper, WJ- 140 engine oil filter paper, J-85 engine oil filter paper, 5um fine diesel oil filter paper, C- 170 diesel oil filter paper base paper. Hm- 180 aviation filter paper, J- 180 cotton glue filter paper, M- 150 cotton glue filter paper, non-impregnated 530 filter paper, heat-sealed tea filter paper, K- 120 air filter paper, K-280 air filter paper and K-80 air filter paper. Water purification paper, cancer cell filter paper, filter paper for precision grinder, hydraulic oil filter paper, activated carbon filter paper, activated carbon filter paper special for radioactive gas determination, filter paper containing synthetic fiber, corrugated plate WG-59 filter paper, oil-gas separation filter paper, slit filter paper, smokemeter filter paper, lead smoke filter paper, high-temperature air resistant filter paper, ion exchange resin filled filter paper, cation exchange fiber filter paper, uncoated sterilized asbestos filter board, membrane-covered sterilized liquid purification filter board, Non-film-covered sterilization liquid purification filter plate, SI corrugated filter paper, high-efficiency corrugated base paper, 69 gas mask filter paper, 69 air purification filter paper, 49 air purification filter paper, 0. 1um high-efficiency air filter paper, tea wrapping paper and three filter papers.

3. Paper and paperboard for electrical insulation

There are impregnated insulation paper, power cable paper, communication cable paper, semiconductor cable paper, telephone paper, electrical insulation cardboard, winding insulation paper, electrolytic capacitor paper, capacitor paper, corrugated cable paper, polyester composite insulation paper, double-layer double-density dry electrolytic capacitor paper,1/kloc-0 ~ 330 kv high voltage cable paper, 500kV ultra-high voltage cable paper and porcelain capacitor specialty.

4, industrial and agricultural production supporting paper and cardboard

There are red electro-optic gun paper, cotton tube steel cardboard, filter paper, cartridge paper, fuse paper, sandstone base paper, explosive cigarettes, hard steel cardboard, mild steel cardboard, steel tube, steel base paper, linoleum base paper, (general anesthesia) cigarette paper, silkworm egg paper, jacquard cardboard, accordion box cardboard, asphalt waterproof cardboard, plastic template paper, gold hot pressing copy paper and so on. Water-resistant sandpaper base paper, clock paper, adhesive paper, hygroscopic paper, lacquer paper base paper, bottle mouth sealing liner paper, rice seedling transplanting paper, beet germination paper, onion skin paper, seedling base paper, black hot-pressed paper, PVC heat-sealed paper, battery absorbent paper, parchment paper, 50 1 perforated black belt paper, photosensitive film base paper, wool spinning professional paper, wax stick matches.

5. Other technical papers

Dental engagement paper, blood test paper, gastric cancer test paper, fracture fixation paper, flame retardant paper, carbon-filled heat insulation paper, water-soluble paper, quick-burning paper, bacterial culture paper, high-temperature heat insulation paper, font paper.

Mechanical paper

1. Printing paper includes newsprint, letterpress printing paper, offset paper, gravure printing paper, coated paper, book cover paper, sea newspaper, etc.

2. Writing paper includes writing paper, glossy paper and printing paper.

3. Drawing, drawing paper includes tracing paper, drawing and drawing paper.

4. Electrical insulating paper includes capacitor paper, telephone paper, cable paper and insulating paper.

5. Cigarette paper includes cigarette paper and cigarette holder paper.

6. Absorbent paper includes blotting paper, filter paper, steel paper base paper and parchment base paper.

7. Instrument paper includes typed telegraph paper tape, reel telegraph, punched card paper, etc.

8. Photosensitive paper includes photographic base paper and photosensitive base paper.

9. transfer paper base paper includes carbon paper base paper, typing wax paper base paper, etc.

10. industrial technical paper includes jacquard paper, sandpaper base paper, paper rope paper, moisture-proof base paper, corrugated base paper, etc.

1 1. Packaging paper includes cowhide packaging paper, straw pulp packaging paper, wood pulp packaging paper, waste paper packaging paper, reed pulp packaging paper, miscellaneous pulp packaging paper, plant parchment paper, imitation parchment paper, carton paper, match paper, paper bag, etc.

paperboard

1. Binding boards include gray waste boards, binding box boards, etc.

2. Box-making boards include straw board, white board, corrugated board and box board.

3. Electrical insulating cardboard includes electrical insulating cardboard, lightning conductive cardboard, etc.

4. Cardboard for industrial technology includes ticket board, kraft board, jacquard board, letter board, etc.

5. Building cardboard includes roof cardboard, wall cardboard and linoleum base paper.

6. Shoe-making cardboard includes heel cardboard, rag leather insole cardboard, etc.