Crepe Paper

Crepe paper is a single-layered, highly absorbent hygienic paper made from groundwood and/or secondary fibers. The basis weight is 27 g m . The most important uses are toilet paper, paper handkerchiefs, and cleaning rolls. 

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Paper may also be colored by surface appHcation of dyestuff solutions after the paper has been formed and dried or partially dried by utilizing size-press addition, calendar staining, or coating operations on the paper machine. In addition, paper may be colored in off-machine processes by dip dyeings or absorption of dyestuff solution and subsequent drying, such as for decorative crepe papers. 

Cotton or wood pulp as delivered to nitrocellulose plants contains 6% or more of moisture. This moisture should be removed prior to nitration so that it does not bring about any dilution of the mixed acid and thereby change the course of the reaction. Cotton is usually transported in the form of compressed bales, which are opened and shredded before drying. Wood cellulose, in the form of pressed cellulose pulp or of crepe paper, is dealt with similarly. Dryers for dehydrating cotton or cellulose may be of various types. The simplest is the shelf drier, equipped with mechanical ventilation and heaters situated at the bottom, supplied with water or steam so as to maintain a temperature of 80-100°C inside the drier. 

The nitration plant was identical in principle with that described above, with mechanical stirring. In the German method cellulose in the form of crepe paper prepared from 70% birch and 30% spruce was nitrated. Cellulose, tom to pieces in rollers, was dried to reduce its moisture content from 6-7 to 1.2%. Towards the end of the war the drying stage was omitted at Kriimmel, and cellulose containing 6-7% of moisture was nitrated, since the time saved and the economy in steam achieved then was reckoned sufficient compensation for the need to make use of more concentrated acids. 

The fibers from the fiber-shredding units fall into a fleece shaft with a perforated conveyor belt at the bottom. The fibers are deposited as a thick fleece due to the application of a slight vacuum. A lubricating oil emulsion (e.g. vegetable oil) is added to the fleece shaft to reduce the frictional forces and hence the chafing of fibers. In the absence of binders the fibers can be used as loose wool or stitched or nailed onto a support, such as wire gauze, crepe paper or corrugated paper, into mats. 

One of the true arts, still practised in papermaking, is the colouration of paper. Chapter 10 covers this subject with great delicacy. Explanations are given of how colour is perceived by the human eye and how differences in shade are distinguished. The chemistry of various chromophores is discussed as well as the conditions under which these chemicals are best used e.g. acid dye use in crepe paper, basic dyes in newsprint and direct dyes in printing and writing papers. 

Acid dyes are generally small molecules, with a molecular weight of 350-500, and a small conjugated double bond system (Fig. 10.2), with no attractive forces. As such they have very little afOnity for cellulose fibres. They do, however, have extremely high solubility and normally produce very bright shades. They can be apphed at the surface and they are generally restricted to papers which have a limited use, i.e. crepe paper. 

Creped paper backings can be divided roughly into two groups. 

Thick creped papers with a thickness of more than 300 pm can be used without a backsize coat for high-elongation masking tapes for painting. 

Flat creped papers saturated with rubberlike polymer latices generally have a back-size coating to control the unwind characteristic without impairing the adhesion of paints. In combination with natural-rubber-based adhesives, these tapes are used for masking in the automotive industry, for assembling electronic components, and insulation of low-voltage devices etc. 

Widely used backings are rigid and conformable films, nonwovens, fabrics, creped paper, and foams based on pol)mrethanes, polyolefins and their copolymers, etc. Generally the thickness of the adhesive layer has to be increased with increasing roughness of the substrates. Foams are especially usefid for rugged or profiled surfaces. 

An important element is the interliner, which mainly is coated with a silicone release agent, as described in Chapter 2.4. Glassine kraft paper is used most frequently. Creped paper, rigid and semirigid films are also used. Besides the peel force, stiffness and conformability are significant features of the interliners. More detailed information is in [211, p. 691-705]. 

Gardener, flower, and decoration crepe. Gardener s crepe is a white or colored, highly expandable paper that has longitudinal grooves and serves as decorative flowerpot wrappers. Flower crepe paper is wood-free and is used to make artificial flowers. Decoration crepe paper is flameproofed by impregnation with chemicals and is used for decorations of various types. 

Absorbing paper Crepe paper using NBKP 0.002 0.005 Less than 0.5 0.08... 

Pressure sensitive tapes and labels are offered with a variety of backing materials such as crepe paper, aluminum foil, fabric, cellophane, kraft paper, cellulose acetate, polyester film, polyethylene, polypropylene, plasticized poly (vinyl chloride), woven glass fiber cloth, or other flexible materials. Pressure sensitive adhesives may be applied from solvent, latex, hot melt, or radiation cured 100% solids systems. A wide variety of coating methods are utilized such as roll coating, calendering, slot die, and transfer coating. 

German troops had no protection similar to American and British covers and capes, but relied on a gasplane or antigas sheet made of treated crepe paper, parchment paper, wax paper, rubberized fabric or plastic coated fabric, about four feet by seven feet in size. Troops could have used these sheets to cover supplies or weapons, and could convert them into protective capes by cutting a hole in the center. ... 

Defoamers are based on ->fatty acids, - fatty alcohols and - fatty acid esters and are available in paste, solid or liquid form. - Fatty acid ethoxy-lates, - fatty alcohol ethoxylates and - fatty acid ethanolamides with only a few EO are also used. Aids for creping paper control the adhesion of the sheet to the creping device. Among others, animal glues (- glue, animal) are used. 

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