FI73268C - Procedure for dry decolouration of secondary fiber sources. - Google Patents

Description

li 73268

Method for removing ink from secondary fiber sources by the dry method

Commercial production of different types of papers 5 requires the use of waste paper as a source of paper fibers due to the high cost of new fibers. Before such secondary fiber sources are used to make a commercial product, it is necessary to treat the fiber source to remove unwanted chemical constituents. The most significant impurities to be removed are printing inks or inks, which degrade the color and whiteness of the secondary fibers used as raw material. The ink layers on the paper are extremely thin, 15 and are roughly or about 0.0025 mm thick. From a chemical point of view, printing inks are usually mixtures of pigment or organic dye, binder and solvent. Some printing inks also contain metallic desiccants, plasticizers and waxes to achieve the desired properties »Thus, their chemical composition can be very complex. However, inks should not be included in the same group as other additives or impurities, such as varnishes, adhesives and thinners, which are chemically and physically different in nature, as deionized experts know.

The purification of secondary fibers has in the past generally been done using various methods for waste fiber sources. The most common treatment is chemical wet aniseing. For example, U.S. Patent 3,098,784,

Gorman, a method for deinking printed paper by slurrying printed paper in water containing 0.2 to 0.5% (by weight of paper) of a water-soluble nonionic surfactant at a temperature of about 30 to 80 ° C is described. 35 The treatment is carried out in a conventional pulp defibering machine, in which the paper raw material is comminuted into approximately 2,73268 separate fibers. U.S. Patent No. 3,179,555 to Krodel et al. Describes an aqueous process that uses certain salts to effect a change in the zeta-potency between ink particles and material particles.

A detergent is used to emulsify the separated ink particles, whereby the ink particles can be removed from the pulp by washing. U.S. Patent No. 3,377,234 to Illingworth describes a melt-10 agent for use in aqueous solution consisting of a mixture of alkyl sulfates, alkyl aryl sulfonates, and sodium polyphosphate. U.S. Patent 1,422,251 (1952); Billingham, describes the comminution of waste fiber sources into a preparation for wet decontamination. U.S. Patent No. 15,018,938 (1935) to Wells describes a wet decontamination process in which waste paper is comminuted in a soap solution with a hammer mill. U.S. Patent 2,926,412 (1959),

Altmann et al., Describes a wet deinking process in which slurried waste paper (3.25% water content) is coarsely ground and then ground at a temperature below 45 ° C to remove ink from the fibers. DE patent 2,836,805 (1979) describes the melting of waste paper in a fiberizer at a concentration of 3 to 5% in the presence of electrolytes, whereby the fibers swell and the printing inks crumble. However, these and other wet decontamination methods can be expensive and generate large amounts of sludge, causing a disposal problem. In addition, there are certain types of paper that cannot be successfully deinked by conventional wet methods because these papers do not react chemically with the deinking agents.

Other methods of treating waste fibers have focused on separating impurities other than inks, such as plastic coatings and various particulate matter, from waste fibers. For example, FR Patent 35 1,295,608 (1961) describes the recovery of waste paper coated with synthetic material or plastic films by contacting the waste paper and rubbing the slurry in a cholester. The hydrophobic plastic particles can be separated from the hydrophilic fibrous material broken down by the cholester into particles (fibers) smaller than the plastic particles. GB Patent 940,250 (1963) describes a method for recovering fibrous materials from waste paper products coated with synthetic resins in the form of a rigid film. The waste material is subjected to a strong mechanical treatment in the presence of water at a concentration of less than 70% by weight to decompose the material into fibers, leaving the synthetic resin film in relatively large pieces. GB Patent 1,228,276 (1971) describes a method for recovering fibrous material from plastic-coated or plastic-containing waste paper. The waste paper is defibered in water, whereby the plastic separates from the fibers as small particles. The plastic particles are then separated from the fibers. In the Russian article "Dry Comminution of Waste Paper", M.V. Vanchakov, V.N. Erokhin, M.N. Anurov (January 14, 1981) describes the dry grinding of waste paper 20 as a pretreatment prior to a water fiber, which separates large contaminants such as fasteners, fabric, polyethylene films, and others. The ground material was passed through separating sieves with 4 mm and 8 mm holes and the portions passed through the sieves were defibered in a water fiberizer. However, as mentioned above, none of these methods is a deinking method. They all concern the removal of plastic films and coatings, which parts stand out in relatively large pieces. All of these methods, with the exception of the Russian article, use water and cannot therefore be considered as dry methods. On the other hand, the Russian article does not deal with deinking, but with the removal of large contaminants instead of fine ones.

Other known methods for treating waste paper still use different approaches. Example 4,73268 to U.S. Patent 3,736,221 (1973) to Evers et al. Describes a process for making shaped articles from waste paper by defibering the waste paper in a hammer mill, coating the fibers with an aqueous binder, pressing under pressure, and heating. No attempt is made to remove ink from the waste paper. U.S. Patent No. 4,124,168 (1978) to Bialski et al. Describes a method for recovering various types of waste paper from a waste mixture by fragmenting the source materials and separating the various components based on their comminutability. This method only sorts the different types of waste paper in the mixture and does not attempt to remove printing ink from the waste paper. DE 1 097 802 (1961) describes a method for recovering waste paper by tearing and cleaning the paper, crimping and rolling the torn paper practically dry and defibering it dry, possibly in the presence of dry steam. This method seeks to overcome the difficulties encountered in defibering waste-20 families coated with hydrophobic materials that do not respond well to methods using water. However, the publication does not state that inks could be removed by such treatment.

Thus, there is still a need for a deinking process that avoids or minimizes the formation of sludge and minimizes chemical costs. Although various known methods have sought to meet this need, none of these methods have been successful.

30 A deinking method has now been invented which is simpler and more economical than conventionally used wet deinking methods. In general terms, the method (a) mechanically defiberizes the waste ink source or feedstock containing the printing ink in a substantially dry, preferably air-dry, manner, thereby forming substantially discrete fibers and fines; and (b) 5 73268 separating the fines from the fibers. The defibering is done with the waste fiber source air-dry or sufficiently dry to prevent the resulting fibers and fines from sticking. The fines, which include the ink-5-containing particles, can be removed or separated from the fibers, for example, by sieving with a sieve with openings small enough to leave the fibers on it, but still large enough for the fines to pass through. The fines may include ink particles, fibrous fragments containing ink, other ink-containing particulate substances such as additives or fillers, fibrous fragments formed during defibering, and additives or fillers in the waste fiber source. In any case, it is clear that at least 15 parts of the fine parts are ink-containing fine parts or ink particles.

As used herein and in the appended claims, the terms have the following meanings: "Secondary fiber source" means pulp products containing printing ink 20, such as printed waste paper, recovered for use as paper fiber sources.

"Air dry" means that the moisture content of the secondary fiber source is in equilibrium with the prevailing ambient conditions.

25 "Substantially loose fibers" means substantially separate fibers, allowing some fiber aggregates to be multiple in length by diameter.

The secondary fiber sources typically contain from about 3% to about 9% by weight of moisture, which for the purposes of this invention is approximately equal to the moisture content of air-dried paper. Therefore, it is preferable that in the practice of the present invention, the fibrous secondary fiber source does not contain or add extra water. It has been found that as the water content of the paper 35 increases, the energy requirement of the defibering device increases rapidly. This increase in energy tends to destroy 6,73268 fibers, resulting in undesirable fiber breakdown. As the water content increases, the fibers and fines formed during defibering also tend to stick or agglomerate with each other, which can clog the device, prevent separation, and reduce the yield of usable fiber. Thus, the secondary fiber source is approximately dry when defibering is performed, and although water may be present or added, it should not be so present as to cause undesirable or uneconomical degradation of the fibers or energy consumption or clogging of the defiberist. The exact numerical upper limit of the water content depends mainly on the characteristics of the secondary fiber source and the operation and economics of the defibering device used in the process. These limits can be determined experimentally by those skilled in the art. In general, however, a moisture content of about 20% by weight of solids is considered to be a practical limit in most cases.

The method of the present invention is particularly useful for removing printing inks from secondary fiber sources treated or coated with a surface adhesive or liner. The adhesive acts as an insulator against the ink by preventing the ink from penetrating when it is applied to the secondary fiber source. In such cases, at least a portion of the adhesive or coating is removed with the ink particles during defibering and separates from the fibers. Examples of lining coatings or surface adhesives are starches, casein, animal glue, carboxymethylcellulose, polyvinyl alcohol, methylcellulose, wax emulsions and various resin polymers.

The discrete fibers without hydration obtained by the process of this invention (which is characteristic of fibers obtained by wet deinking processes) are suitable as secondary fibers and can be used in pulp products such as tissue paper, papers, wadding, sheets, wrapping paper, newsprint, and the like.

7 7 3268 for manufacture.

Figure 1 is a perspective view of an exemplary defibering apparatus used to implement the method of the present invention.

Fig. 2 is a perspective view of a fiberizer of the type shown in Fig. 1 with the front cover opened and the impeller blades and serrated impact surface visible.

Figure 3 is a perspective fragmentary view of the opened fiberizer with the impeller removed, showing the opening 10 through which the treated fibers are removed from the treatment chamber.

Figure 4 is a side view of a partially cut fiberizer illustrating the operation of the device.

Figure 5 is a perspective view of a defiberizer 15 converted to operate continuously.

Figure 6 is a flow chart illustrating the method of the invention.

Fig. 7 is a block diagram illustrating the use of the present invention in papermaking.

The invention will be described in more detail first with reference to Figure 1.

A turbine mill was used to collect this information as the fiberizer of Figure 1. However, it will be apparent to those skilled in the art that various defibering devices are available for carrying out the method of this invention, such as hammer mills, disc mills, vane rippers, etc. In general, the defiberizer 1 A secondary fiber source, for example printed waste paper, which may be torn, is fed to the defiberist through the feed opening 3 and the waste paper is comminuted or defibered into substantially individual fibers and fine particles. An internally mounted fan draws air in through the inlet 3 together with the waste paper and blows the air out through the outlet 35 4, transporting the fibers and fine particles with the air. The fibers are collected in a tubular perforated bag, ____ .. Γ ”8 73268 through which openings fine particles can penetrate and into which the fibers remain. The material of the perforated bag 5, which has been found to function satisfactorily, has a screen size (mesh) of 50 x 60 with an opening of 25.4 mm. The wire through-5 dimension was 0.23 mm (0.009 inches) and the size of the openings was 0.15 x 0.30 mm (0.006 x 0.012 inches). The open area of the screen fabric was 23% of the area. Figure 1 also shows a cooling device with a water supply pipe 6 and outlets 7, which removes heat generated by the action of friction 10 under the action of shear forces on the fibrous material to be fed. With the exception of the tubular perforated bag, the fiberizers of Figure 1 are commercially available devices. Such a fiberizer is described in U.S. Patent 3,069,103. The apparatus used and described specifically in connection with this invention was Pallman Ref. 4 -heater.

Figure 2 shows an operating chamber inside the defibrator, illuminating mainly the position of the impeller blades. The figure shows a toothed, grooved action surface 20 against which the material to be fed rubs against the action of the rotating impeller blades 9. Although not clear from the figure, there is a free space between the toothed contact surface and the wings where the cellulosic materials strike around. The position of the blade relative to the impact surface 25 8 is adjustable, which improves the controllability of the degree of defibering, which is also controlled by the speed of the impeller, the residence time and the nature of the impact surface. The impact surface 8 consists of six detachable segments. They can be replaced by a smaller or larger number of segments with different surface shapes and structures. This flexibility allows unlimited modification and optimization of fiberization. However, the structure described here has worked very satisfactorily. More specifically, the grooves of each of the segments 35 shown in the figure are parallel to each other and spaced about 2 mm apart from the top to the top. Each 9,73268 groove has a depth of about 1.5 mm. The width of each segment in the radial direction is about 10 cm. These dimensions are given for lighting purposes only and are not limiting. The figure also shows in part the action surface on the inner surface of the hinged lid 10 5, which is approximately similar to the already affected action surface 8. When the lid is closed, the two action surfaces form a chamber in which the material to be fed is defibered.

Fig. 3 is a perspective partial view of the defiberizer 10 from which the impeller has been removed, showing an opening 11 through which the defibered material passes before it passes through the outlet 4. The size of the orifice can be varied, which adjusts the degree of defibering by increasing or decreasing the air flow rate and thus the residence time in the defiberizer. The orifice is within a removable plate 12 to facilitate resizing of the orifice. An orifice diameter of 160 mm has been found to be suitable for air 3 at a flow rate of 10 m / min. Figure 3 also shows the impeller blades 13 of a fan for providing air flow through the fiber 20.

Figure 4 is a cross-sectional view of a partially open fiberizer illuminating the operation of the device. The arrows indicate the direction of air and fiber flow. More specifically, the secondary fiber source 15 is led 25 to a feed opening 3 where it comes into contact with the rotating vanes 9. The air flow leads between the rotating vanes of the secondary fiber source and the contact surface 8 so that the secondary fiber source is comminuted into smaller and smaller particles and eventually shrinks or the fibers are reduced to substantially discrete fibers and fines. The centrifugal forces generated by the impeller blades tend to push the particles, primarily the larger particles, to the tip 16 of the angle between the contact surfaces. These forces tend to prevent the larger particles 35 from escaping until they are completely defibered. When substantially complete fiberization has taken place, the comminuted solid materials pass through the opening 11 of the removable plate 12. The fan blades then push the fibers in the air stream out through the outlet 4.

Figure 5 illustrates the operation of the previously described fiberizer, which, however, has been slightly modified for continuous use as would probably be required for commercial production. In this embodiment, the feed opening 3 is tubular instead of the funnel shown in Fig. 1. 10 The supply pipe provides a continuous supply of a shredded secondary fiber source of suitable size and quality. Generally speaking, such material may be in pieces of about 2 to 15-25 cm in size or smaller, and should not contain scrap to protect the defibering device. However, the particle size and shape of the material to be fed depends on the performance of the fiberizer used, and is not a limiting factor of this invention. For example, a shredder can be used and was used to tear the secondary fiber sources used to obtain the results given in tau-20 locks I-III. Another variation shown is a continuously moving screen 18 on which the fibers are collected into a web or sheet 19. The density of the screen is selected so that the fines pass through it, preferably by means of a vacuum chamber 20 into which the fines are collected and passed to an appropriate collection point. W. S. Tyler Incorporated screen fabric with a mesh size of 150 (150 apertures 25.4 mm), a yarn diameter of 0.066 mm (0.0026 inches), an aperture size of 0.10 mm (0.0041 inches) and an open surface area of 37 , 4%, has been found to work best in producing a web having a basis weight of about 20 g / m 2 (12 lb. / 2800 ft) or less. Thicker plates tend to enclose fine portions regardless of the size of the screen openings. Shown in dashed lines, a modified outlet 4 is shown, enlarged to correspond to the width of the moving screen. In actual continuous operation, for example, perforated waste paper was fed to the Ball Fiber at a speed of 11,73268 at 0.7 kg / min. The defibrator was adjusted so that the distance between the toothed impact surface and the impeller blades was 3 mm. A removable plate with a 140 mm wide opening was mounted behind the impeller, which rotated at 5,430 rpm without load. The air flow through the fiberizer 3 was about 10 m / min. Cooling water was fed to the cooling jacket at a rate of 2 l / min. The water temperature initially measured was 15-15.5 ° C and stabilized at 19-20 ° C as the experiment continued. The speed of the wire receiving the defiberized material from the defiberizer was adjusted to 107 m / min.

About 18.85% of the secondary fiber source passed through the wire in fine portions, while the remainder remained on the wire as a dry deinked product. The fines contained about 75% by weight of fiber particles and about 25% by weight of clay 15 (filler).

Figure 6 is a schematic diagram of the entire method of the present invention. More specifically, the secondary fiber source 15 is fed to a fiberizer 21 that is similar or functionally similar to the type of fiberizer shown in the previous Figures 20. As already mentioned above, for most fiberizers, it is probably advantageous to first rip the secondary fiber source. In the fiberizer, the secondary fiber source, either torn or non-torn, is substantially comminuted into individual or discrete fibers 25 and fines and collected on a moving screen 18. The deposition of fibers on the screen is facilitated by a vacuum chamber 20 which provides for the removal of fines. The fines contain a large portion of the ink contained in the raw feed and are collected in a suitable receiving container 22 for disposal. The vacuum in the vacuum chamber is provided by a blower 23 which pulls the fine particles through the screen and pushes them into a receiving vessel 22. The pulp or fibreboard deposited on the moving screen is then recovered by adjusting its thickness evenly with a suitable device 24 and baled in a baler 25. or it is fed 12,73268 directly to a fiberizer where it is made into a fibrous slurry for conventional papermaking. In addition, the recovered fibers can be fed to an air molding machine to produce air-layered webs or sheets. It will be apparent to those skilled in the art that various hardware or devices may be used to perform the functions described above.

Figure 7 further illustrates a method according to the present invention by means of a block diagram showing the entire process 10 for making paper using fibers recovered from a dry deinked secondary fiber source. As can be seen from the diagram, a secondary fiber source containing printing ink (such as printed waste paper) is defibered air-dry into substantially discrete fibers and fine-divided portions. The fines are separated from the fibers by any suitable means so that the recovered fibers remain usable as desired. There are at least seven possibilities. As can be seen from the diagram, the fibers can be baled for later production of the pulp 20 (dashed lines). They can also be fed directly to an air molding machine to produce air-laid webs. Alternatively, the fibers can be purified, for example, by the centrifugal method with water (Tables IV and V) or by wet deinking methods known in the art and exemplified in the wet deinking patents described above. In either case, the fibers obtained can be pulp by soaking in water and diluted to a concentration suitable for papermaking. 30 The papermaking raw material is then layered into a wet fibrous web and dried into a sheet of paper. The various stages of papermaking may vary, but are also well known in the art. The dry-cleaned fiber of the invention is a useful secondary fiber for tissue paper, fine paper, printing paper and other papers.

13 73268

Examples To illustrate the effectiveness of the method of the present invention, six different secondary fiber sources were mechanically defibered in accordance with the present invention as described above using the defiberer of Figures 1-4. The six different samples were a computer result strip, Xerocopy Bond "'", ink-coated UV-cured cardboard (UV-coated cardboard), lacquered cardboard, newsprint, and magazine paper. The second, third, and fourth examples mentioned above are, in fact, impossible to deal with by conventional wet cleaning methods. All secondary fiber sources were air-dry and treated at room temperature. It should be noted, however, that certain inks and adhesives are more oa-15 to handle at higher temperatures, making them more brittle and thus more likely to form fine particles. On the other hand, some inks or adhesives may be thermoplastic and therefore easier to handle at lower temperatures. The optimum processing temperature thus depends on the characteristics of the prevailing secondary fiber source and the economics of obtaining a suitable temperature.

Decontaminated fibers obtained by treating each sample with the method of the present invention (test sample) and uncleaned fibers (control sample) obtained by tearing each sample into small pieces and slurrying them in warm water (43 ° C) with gentle agitation between the fibers. to break the bonds, both were used as an aqueous slurry in preparing 2Q paper test sheets in a conventional manner. The test sheets thus prepared were then examined for degree of whiteness using an Elrepho Photoelectric Reflectance Photometer (ISO 3688) and ash content (as a measure of coating and / or filler removal (TAPPI T211M-58)). In addition, runoff properties (Canadian Standard Freeness TAPPI T227m-58) were also measured from 25 test and reference masses.

* "Husky2 Xerocopy Bond, (Kastaman Kodak), photocopy paper ____ .. τ ~ 14 73268

The results are shown in Tables I, II and III.

Table I

(Canadian Standard Freeness (incl.)) Sample Comparison Experiment 5 Computer Strip 380 590

Copy paper 500 700+ UV-coated cardboard 500 700+

Lacquered cardboard 500 700+

Newspaper 100 270 10 Magazine 130 280

Table II

(Ash content (% by weight) Sample Comparison Experiment

Computer strip 10.3 6.2 15 Copy paper 9.3 4.6 UV-coated cardboard 4.6 2.4

Varnished cardboard 5.1 3.2

Newspaper

Magazine 23 15 20

Table III (Degree of whiteness) Sample Comparison Experiment

Computer Strip 72 77

Copy paper 81 85 25 UV-coated cardboard 75 78

Varnished cardboard 79 82

Newspaper 35 44

Magazine 51 58 30 As can be seen from the results, the final whiteness and ash content of the sheet were improved when the fibers obtained by the process of the invention were used to make the sheet. In addition, the method of the present invention also improved the flow properties of the pulp (degree of grinding).

35 There had also been a dramatic reduction in the number of visible ink spots in the desiccated samples compared to the untreated samples. Although not specifically measured, this improvement is reflected, at least in part, in whiteness measurements.

In addition to being used as the sole treatment for a secondary fiber source for papermaking feedstock, the dry cleaning process of the present invention can also be used as a pretreatment followed by further fiber cleaning or conventional wet deinking treatment. Using this method as a pretreatment, it reduces wet sludge formation in wet deinking (which minimizes the waste problem caused by sludge formation) and lowers chemical costs, as some of the ink has already been removed before the next wet deinking. Tables IV and V show comparison results for decontaminated cigarette packs showing that some physical properties of the two secondary fiber sources (cigarette packs) have improved after the packs have been dry-cleaned and subsequently purified in a hydroxyclone (centrifugal cleaning).

20 Table IV

(WINSTON Cigarette Packs) Wet Clean Dry Dry Clean + Background Clean Centrifugal Cleaning

Grinding degree 616 619 700

Elrepho whiteness 76.5 75.3 77.6

Ash,% - 3.3 1.8

Table V

30 (SALEM Cigarette Packs) Wet Cleaning - Dry Cleaning - Background Cleaning + Background Cleaning Centrifugal Cleaning

Degree of grinding 636 658 699 35 Elrepho degree of whiteness 81.2 79.5 79.9

Ash,% - 3.0 2.1 __ττ —- ie 73268

In both tables, the first column contains the physical properties of the product obtained by treating the sample with a conventional wet deinking method. The method used has nothing to do with the method according to the invention, but only serves as an aid for making comparisons. More specifically, the deinking solution contained 3.0 g of sodium hydroxide, 0.2 g of tetrasodium pyrophosphate, 0.2 of Armak Ethofat 242/25 surfactant and 1667 ml of water. Thus, the backing solution was heated to 80 ° C and 50 g of oven-dry waste paper, cut or torn into pieces about a centimeter in diameter, was added with stirring.

After the sample decomposed into fibers, it was washed three times by diluting with water to a concentration of 15%. Then the degree of grinding of the washed product (Canadian

Standard Freeness) was measured and made into test sheets for whiteness measurements.

The second column shows the corresponding results for the products obtained by the dry cleaning method 20 according to the invention described above.

The third column shows the results for the products obtained by centrifugal purification of the fibers obtained from the dry sieving step according to the second column. More specifically, the dry-cleaned fibers were slurried in water 25 so that the content of the slurry fed was about 0.5% by dry weight. The slurry fibers were fed to a Bauer "600N" Centricleaner at a gauge pressure of 2.8 atm at a rate of about 150 1 / min (40 gallons per minute, assumed to be a US gallon). conical with a nominal internal diameter at the top of 7.5 cm and a height of about 90 cm The centrifugal cleaner separates the fibers from smaller and higher density particles · in a manner familiar to those familiar with mechanical separation methods.

17 7 3 2 6 8 These results illustrate the effectiveness of the dry cleaning method of this invention as a pre-cleaning treatment, particularly with respect to the removal of fines, as measured by the increased degree of grinding of both samples. In addition, both washed samples had a slightly better degree of white-5 than dry-cleaned products.

Although not described herein, dry-cleaned products can also be wet-cleaned by conventional methods well known to those skilled in the art. For example, the dry-deinked fibers can be slurried in the deinking-10 solution for a period of time such that the excess ink is removed and washed and / or centrifuged.

Therefore, it should be noted that the present invention has use as a method combined with either the deinking process per se or other papermaking methods. In addition, the invention has numerous hitherto unattainable advantages.

Claims (14)

A method for deinking a secondary fiber source containing printing ink, characterized in that the secondary fiber source is mechanically decomposed into substantially separate fibers and fines into said fibers, said secondary fiber source being substantially fine portions of said fibers, said fibers being suitable as secondary fibers. A method according to claim 1, characterized in that said secondary fiber source contains at most about 20% by weight of moisture. A method according to claim 1, characterized in that said secondary fiber source is air dry. A method according to claim 1, characterized in that said fines are separated from said fibers by passing the fines through a screen having a sufficiently small screen size to prevent the passage of said fibers. A method according to claim 1, characterized in that the separated fibers are slurried directly in water for the production of a pulp product. A method according to claim 1, characterized in that the separated fibers are fed directly to the air molding device. A method according to claim 1, characterized in that the separated fibers are formed into a substantially uniform sheet and baled. A method according to claim 1, characterized in that the separated fibers are purified in an aqueous solution. 19 73268 Process according to Claim 6, characterized in that the separated fibers are purified in a hydrocyclone. 10 UV-cured ink-coated cardboard, lacquered cardboard, newsprint, cigarette packs or magazine paper. Method according to Claim 6, characterized in that the separated fibers are purified by a wet deinking method. A method according to claim 1, characterized in that the secondary fiber source is computer print strip paper, photocopy paper, 12. A method of de-inking a secondary fiber source containing printing ink treated with a surface adhesive, characterized in that the secondary fiber source is mechanically decomposed into substantially separate fibers and fine portions containing ink and glue, said disintegration into fibers occurring in said secondary fiber. air dry or sufficiently dry to prevent gluing of the resulting fibers and fines, and separating the fines from said fibers, said fibers being suitable as secondary fibers. 13. A method of making paper from a printing-containing secondary fiber source, characterized in that a) the secondary fiber source is mechanically decomposed into substantially discrete fibers and fines, said disintegration occurring into said fibers, said secondary fiber source being substantially air-dry or sufficiently dry ; b) separating said fine portions from said 35 fibers; _______ - ~ .. - 73268 c) slurrying said fibers in water to obtain a papermaking raw material; d) depositing the papermaking raw material wet to form a fibrous web; and 5 e) drying the web. A secondary fiber usable for recycling in the manufacture of a pulp product and made from a secondary fiber source containing printing ink, characterized in that it consists of discrete fibers obtained by mechanically disintegrating said secondary fiber source into fibers when air-dry or sufficiently dry. and that said discrete fibers are separated from the resulting fine particles, and that said discrete fibers do not exhibit the hydration characteristic of fibers obtained from wet recycling. 2i 73268