JPS6030398B2 - How to recycle paper products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recycling paper products, and more particularly to a method for recovering cellulose fibers from paper products and similar cellulose-containing materials in a form suitable for producing new cellulosic products.

Generally speaking, the present invention relates to the defibration of essentially clean used paper products, the defibration of used paper products containing foreign matter,
It relates to defibrillation, which simultaneously removes ink and other contaminants from used paper products, and to partial fiberization and separation of various used cellulosic materials.

The increasing restrictions imposed on the wood-based industry have placed increasing demands on paper and paper boat manufacturers to seek other sources of cellulosic fiber to manufacture their products.

As a result, the regeneration of cellulose fibers from post-consumer paper and paperboard has become very important. In 1974, 35% of paper and paperboard manufactured in Australia was made from recycled fibres, and this proportion is set to increase in the future (Appitajoumal, 29M.
3 pp. 196-200, November 1973 R. W.
Nbddren).

Recycled used paper and paper products are widely used in industrial, commercial,
Collected from the household sector. Commonly used materials include boxes, carton board, fine paper, newsprint, wrapping paper and consumer container board. In certain cases,
Although used paper and paperboard are essentially free of contaminants, used paper and paperboard often contain unwanted foreign matter. The degree and type of foreign material varies widely and varies depending on the source of the paper product, but typically includes metal, glass, plastic, paper, pressure sensitive tape, asphalt,
Contains contaminants such as laminate, carbon paper, sand, stones and household debris. In some cases, printing and ink on paper surfaces are also considered contaminants. All undesirable components must be removed and rendered non-hazardous before being introduced into the paper and paperboard making machine.
Machines that regenerate fiber from clean or dirty materials generally disperse used paper fibers to produce an aqueous suspension. The dispersed fibers produced (also known as stock or pulp) may be further processed to remove or disperse any contaminants present in the raw feedstock. Many of the machines in use in recent years that convert used paper and paperboard into pulp slurry are
rati. n. f S■Ck for papenna
King” J. 100-14 by Phenson in N.S.
6 pages first edition (MeG mouse w-Hill S.N.Y. 1951
)It is described in. A machine that is widely used and represents many functions is known as a hydropulp machine. This pulp machine basically consists of a vertical, bowl-shaped tank with a multi-blade rotor fitted through the base.

The used paper and paperboard are dumped into a bowl with sufficient water and the final result is a 3-5% pulp slurry.
A constant punch is applied to the contents of the hydropulp machine in such a manner as to gradually release the fibers from the feedstock outside the multi-bladed row. In batch operations, the defibration cycle can take an hour or more, and fiber release is often aided by the addition of heat and appropriate chemicals. Heating and chemical addition are essential when concomitant ink release occurs. Debris removal within a hydropulp machine involves contamination and can proceed in many different ways.

Contaminated foreign matter (matchsticks and foamed plastic) floats to the top and can be removed by skimming. Vehicle foreign objects (metal and glass) sink to the bottom and enter a specially designed compartment, from where they are removed by a bucket elevator. Relatively large and essentially medium loose materials (plastic sheets, ropes, threads, lanterns) are removed by wrapping them around a suitable length of barbed wire and pulling them out of the bowl. Used paper materials and contaminants that are particularly difficult to handle in hydropulping machines are high-moisture strength paper, pressure tape, waxed cartons, glassine paper, plastics or metals or adhesives, or other materials containing asphalt as a waterproofing agent. Paper made of thin layers of laminated materials.

High-temperature, high-strength paper (in which the natural bonds of cellulose fibers are strengthened by the power of resin) cannot be easily dispersed in a hydropulp machine.

The high-temperature, high-strength paper is mirror-divided into four flakes by individual fibers. If this wet strength paper makes up the majority or part of the feed V feed, additional processing must be performed after hydropulping to remove flakes. According to Nneddern, it is said that dispersing high-temperature wet strength paper with a hydropulp machine requires a force of 450 kWhr/ton, which is greater than dispersing with an air drying kraft valve. In materials containing sensitive tapes, waxed cartons and altruts, the problem encountered is that when these are present as foreign substances, adhesives, waxes and bitumen combine with the fibers to form a pulp dispersion in the hydropal machine. . These adhesives, waxes and asphalts (collectively known as bitumen) are not removed in the next stage of pulp production and become defects within the final paper or paperboard. Industrial experience shows that even amounts of bitumen as low as lk9 per 200 tons of recovered paper can render the entire batch unfavorable for consumable packaging sogboard. Apart from this, the presence of bitumen particles has the disadvantage that the final paper or paperboard is difficult to print. As a result, this type of contamination leads to fibers regenerated having much lower applicability than would be warranted by the inherent mechanical properties of the fibers themselves. In short, existing used paper and paperboard recovery techniques, such as those exemplified by Hyde-o-pulp processing, have a number of drawbacks. Namely, 1 Defibration rates are relatively slow, with 1 hour or more being common in batch operations.

2 Due to the inherent nature of hydropulping processing, the stock is relatively highly diluted (3-5% solids content).

This creates liquid flow disposal problems, particularly when chemicals are used to aid in hydropulping. 3
Means for removing contaminants vary and are complex.

4. It is difficult to recycle high-temperature wet-strength paper, and the energy required for it is expensive.

5 Insufficient removal of bitumen from stock;
This results in defects in the final product.

6 In hydropulping, it is not possible to separate fiber fractions of different strength unless equipment is provided for this, unless initial hand sorting is performed prior to introduction into the Hyde0 pulping machine.

As a result of various studies, the present inventor found that paper products, etc. can be completely or partially defibrated using pressure pulping technology, and has thus completed the present invention.

Therefore, the method of the present invention can provide a method for recycling paper products that overcomes the drawbacks of the above conventional method.

That is, the process of the invention consists of subjecting the cellulose-containing material to a highly pressurized environment, rapidly transferring the material under turbulent conditions to a low pressure environment, and separating the cellulose fibers from the resulting product stream. The high pressure environment may be a liquid and/or gaseous environment.

If ink and/or other coatings are to be simultaneously removed from a cellulose-containing material, the material may first be impregnated with water and then heated prior to or concurrently with being subjected to a high pressure environment.

When the cellulose-containing material consists of a mixture of strong and relatively weak cellulose fibers and it is desired to separate the fibers from each other, the resulting product stream is divided into a downward stream containing relatively weak and strong cellulose fibers, respectively. separated into the upper flow.

The present invention can also be pulped whenever produced by these methods.

The carrier medium for the cellulose-containing material may be a gas or a liquid or a mixture of gas and liquid.

The cellulose-containing material may be at ambient or elevated temperature before being transferred from the high pressure environment to the low pressure environment, and the process of the invention may be carried out in the presence or absence of added chemicals.
When the invention concerns the simultaneous removal of ink and/or other coatings, the initial impregnation of the cellulose-containing material is usually carried out with just water, but small amounts of alkali may be added.

The final processing step of separating cellulose fibers from ink and other coating particles may be performed by many known methods.

Accordingly, the present invention provides deinking and uncoating methods - in some embodiments, with or without the use of relatively small amounts of deinking/decoating agent chemicals.

As a result, the fluid disposal problems associated with the present invention are less severe than with other methods. Furthermore, the deinking process of the present invention is rapidly and well adapted to simultaneous or sequential processing of a wide range of paper products of different types. That is, the speed and efficiency of the deinking/decoating process is minimally affected. In summary, the invention can be applied to achieve the following results.

1 Defibration of essentially post-consumer paper and paperboard to obtain moisture, dry or moisture defined products.

2. Essentially defibrates high-temperature strength paper with minimal chemical use or inconvenience to obtain a pulp product that requires little secondary treatment prior to introduction into a paper or paper board machine.

3. Separation of cellulose fibers from foreign matter in a simplified manner relative to existing processing methods, and at the same time removing most of the Bitumen-type materials from the raw material. 4. Mixed used paper and paperboard materials are separated into relatively weak fiber components in response to the process of the invention.

5 The recycled material is defibrillated and deinked,
A fast processing method is provided to obtain a pulp product that is essentially free of ink and other coatings or has a reduced amount of ink and coatings.

As will be apparent from the above and following discussion, the present invention has the following advantages over known used paper and paperboard recycling methods.

1 Rapid defibration cycle 2 Minimum use of heat and chemicals 3 Simplification of contaminant removal techniques 4 Reduction of water usage 5 Essential removal of bitumen from stocks 6 Use of material without manual sorting as pre-treatment BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings.

In the figure, at 1 the regenerated cellulosic material enters the system. If the material contains glass, metal or foreign matter and is heavy, some of it can be removed in the device 2 by known methods. The known methods are magnetic selection,
Air friction or flotation. The processing line device 3 is a rough cutter which reduces the size of the material somewhat if necessary. Although not required, this splitter is advantageous for spent material that leads to inefficient packing and volume utilization in the next processing step. The cellulose material to be regenerated is divided by the dividing machine 3.
and enters a digester 12 capable of withstanding temperature, pressure and chemical conditions suitable for the practice of the present invention.

Although the drawing shows a batch type digester, the digester 12
It can also be in batch or continuous format. This does not affect the principles of the invention. However, for proper implementation of the present invention, the digester must be of a design that allows for rapid release of the contents at the end of a preselected treatment condition. In batch operation, the digester may be filled with the cellulosic material to be regenerated and water or liquid added from tank 6.

Water or liquid for defibrillation is not essential to the practice of this invention and may be omitted if a dry or green limited product is desired.

However, in many cases it is preferred to use water or a liquid as it reduces the energy required for the subsequent overall defibration step. If water or liquid is added, sufficient water or liquid should be introduced to obtain uniform fiber infiltration conditions. In practice, it is preferred to use a minimum of 4 parts by weight per part by weight of cellulosic material. If ink and/or coating removal is to be performed essentially simultaneously with defibrillation, the use of a liquid is essential.

The chemicals used for the deinking fluid may include alkalis such as soda ash, caustic soda, sodium silicate, sodium peroxide and sodium sulfate. It may also contain a bleaching agent such as hydrogen peroxide. It may further contain a surfactant. The concentration and nature of the deinking fluid will be determined by the particular feedstock. For example, a highly printed material will require a more concentrated liquid than a less printed supply stock. However, in most applications, the total combined amount of dissolved liquid components is unlikely to exceed 5% by weight of the total liquid, and is generally lower than that when adding water to the digester. For non-deinking applications of the invention, the performance of the invention is determined by adding a small amount of alkali and/or surfactant to water (2% by weight of water).
(below) can be improved in certain environments by dissolving them.

Although not required, this is advantageous when processing high temperature paper or paperboard or other relatively impervious stock. When using water or liquid, the water or liquid may be added wet or cold. If the components in the digester are then to be heated, it is advantageous to use hot liquid or hot water, as this reduces the required processing time. After filling the digester 12 with the regenerated cellulosic material and optionally water or liquid, the digester is sealed.

The components of the digester may then be heated. If the material printed by the method of the present invention is to be simultaneously defibrated and deinked, or if high-humidity strength paper is to be defibrated, heating is required. The digester 12 may be heated in a variety of known ways;
Preferably, the heating is done by direct injection into the bottom of the tank. If heating is performed, the heating rate is preferably as fast as possible. That is, heating times of 2-3 minutes are preferred over more extended temperature approaches. The maximum temperature of the components within the digester will be governed by the nature of the material being processed.

Deinking or defibrillating high-wet strength paper and cardboard or board requires higher processing temperatures than relatively thinner and more easily wetted qualities, but in many cases
It may be sufficient for the practice of this invention that the components within the digester have a maximum temperature of less than or equal to 80:00. Once the required operating temperature is reached, the digester components may be maintained at that temperature, if necessary for a short period of time.

Otherwise, the digester is further pressurized by supplying a suitably water-soluble gas or gas mixture from the compressed gas tank 9.
Although it is within the scope of this invention to introduce the gas or gas mixture before heating the digester components, it is generally preferred to introduce the gas after the desired operating temperature has been reached. If the digester components were not heated, a moderate water soluble gas or gas or gas mixture would be present in the digester 12.
is introduced immediately after it is sealed.

Preferred gases for the present invention are free of carbon dioxide, nitrogen, halocarbons, hydrocarbons and particles.
Contains low oxygen content fuel gas. Air may be used if desired, but in all gas mixtures containing free oxygen, it is desirable to limit the final digester pressure to an extent that makes the system safe from uncontrolled oxidation and explosion. If you are using a liquid containing a strong alkali such as caustic soda,
It may be advantageous to limit the introduced gases, carbon dioxide and sulfur dioxide, to a range where reactions between the introduced gases and the liquid alkali component are not significant. The pressure of the gas or gas mixture should be such that sufficient fiber dissociation is obtained during the subsequent transfer operation. The optimum gas pressure will be governed by the very nature of the cellulosic material being processed, and the temperature, time and liquid composition can vary depending on the particular embodiment of the invention.
In many cases, an applied gas pressure of 20M a or less is sufficient for the practice of the invention. Once the liquid or water has been added to the digester, the digester 12 is then pressurized with gas from tank 9 and the digester components are allowed to submerge for 2-3 minutes under the applied gas pressure. During this soaking period, the applied gas pressure forces the water or liquid into the interstices of the used paper, used paper board, or similar material. This weakens the internal fiber hydrogen bonds in the case of untreated papers and paperboards or the resin-setting bonds in the case of high-wet strength papers. Hydrolysis of resin-set bonds is aided by heat and the presence of alkaline chemicals in the liquid. A similar mechanism occurs in the processing of printed materials. The flow of hot liquid into the printed paper or board is facilitated by the applied gas pressure. The hot liquid causes the cellulose fibers to swell within the paper or paperboard, and the chemicals in the liquid attack the ink-fiber bond and loosen it. At the end of the immersion period, the digester outlet valve 15 is opened and
The applied gas pressure causes the components within the digester to move rapidly into the vessel 16.

If no water or liquid is added to the digester, no immersion period is necessary and the valve 15 may be opened once the desired gas pressure is reached in the digester.

the diameter of the transfer line connecting the digester 12 and the vessel 16;
The design of the digester outlet valve 5 is such that the pressure differential maintained between the digester 12 and the vessel 16 during the transfer period is such that highly turbulent conditions are maintained during the transfer period. This is necessary for practicing the invention. The high degree of turbulence in the moving process imparts shearing and tensile forces to the paper or paper board. This force releases cellulose fibers from the treated material,
Also, in the case of printed feedstocks, ink and other coatings are released from the cellulosic fiber surface. Due to the fixed digester geometry, the degree of turbulence achieved during travel is directly proportional to the gas pressure applied to the digester 12. Relatively high pressures will enhance relatively high turbulence. Hence making fiber dissociation and ink removal more effective. For a fixed gas pressure, the degree of turbulence during the transfer process can be increased by installing airfoil-shaped turbulence enhancers in the transfer line. The speed of the transfer process and the efficiency of fiber dissociation are influenced by the design of the digester outlet valve 15.

For maximum efficiency, valve 15 should be of a full flow type, such as a plug or ball valve, and valve 15 should open as quickly as possible. The maximum operating time from full closure to full opening should not exceed 1 second, preferably less than 0.2 millimeters. The energy used to rapidly move the components within the digester is provided by compressed gas.

The diameter of the line connecting the gas tank 9 to the digester 12 and the design of the valve 8 are such that the line connecting the gas tank 9 to the digester 12 is
There should be free flow of gas. For gas economy, valve 8 should be closed when the digester components have been sufficiently released. The design of vessel 16 should allow rapid separation of the gaseous stream from the product stream.

In the figures, vessel 16 is shown as a cyclone, but a large capacity collection tank could equally be used as an example. The defibrillation effect obtained during the moving process can be further enhanced by placing a plate with a textured surface near the entrance of the container 16.

When the released digester components hit this plate,
Further turbulence is created and additional fibrillation and longitudinalization is achieved. container 1
The gaseous stream 17 from 6 is exhausted to atmosphere or
May be collected in a compressed gas tank.

Product flow from container 16 proceeds to the second step. The nature of the second treatment applied to the product in container 16 will be determined by the implementation of the particular embodiment of the invention. Specific examples and secondary treatments are summarized in Table A below.

Table A Secondary processing of digester products The method of the present invention will be further explained in detail by the following examples.

EXAMPLE 1 This example relates to defibrillating recovered newspaper and corrugated boxboard according to the present invention.

The material to be treated is loaded into the digester along with water at 18° C. and the device is sealed.

Further pressurize with nitrogen gas. After immersion for 3 minutes under gas pressure,
The components (contents) in the device are rapidly transferred to the bottle collector at atmospheric pressure by opening the digester outlet valve for less than 0.1 seconds. The degree of dissociation of the resulting fibers is determined by screening the ejected material on a 0.25 leg slotted screen. The emissive material passing through the slotted screen consists essentially of dissociated cellulose fibers. The total degree of defibration obtained by both samples is directly proportional to the applied gas pressure, the higher the pressure the better fiber dissociation is obtained (see Table IA) Table IA Dissolution of Newspaper and Corrugated Boxboard Effect of applied gas pressure on fibers Digester operating temperature 18qo Water: Used paper = 12.7:1 Total defibration of recovered material under a given pressure is affected by temperature, the higher the operating temperature gives better scale fiber results.

Table IB shows the results of heating the unreleased contents from 50 to 11,000 °C. Temperature influence on No. IB expressed fibers Pressure inside the digester before transfer = 4.83 MPa Water:
Spent Paper = 19.2: I Another factor influencing the degree of fiberization obtained by the method of the invention was the ratio of water to spent paper solids loaded into the digester.

The results of varying this ratio in newspapers are shown in Table IC. All examples listed in Table IC were conducted at 18°C and an initial digester internal pressure of 4.83 MPa. Table IC Influence of water:used paper solids ratio in defibrinating newspaper When air-dried raw materials are defibrillated by the method of the present invention,
Relatively high initial digester pressures are necessary to obtain the same degree of defibrillation as is obtained when water-saturated feedstocks are processed.

Therefore, after the first release, the partially defibrated and lengthened product is returned to the digester for a second release and so on. Table ID shows the results of continuous discharge of air-dried newspaper from an initial digester pressure of 48.3 MPa. TABLE ID CONTINUOUS DISCHARGE OF AIR-DRIED NEWSPAPERS The example with a water:solids ratio of 0.1:1 is for air-dried newspapers and no additional water added to the digester.

The resulting defibrillation was relatively poor (15.4%), but a dry product was obtained. If water is added up to a water:solids ratio of 7.1, the degree of total defibration increases rapidly. The newspaper was fully saturated with water and the rattan fiber was 62.3%. Dry newspaper at a ratio of 0.1:1 and water-saturated newspaper at a ratio of 7.0:1, although increasing the water:solids ratio to 19.2:1 can improve defibration somewhat further. Particles become smaller in relation to the increase in time. The inherent properties of the inventive process are that the water:solids ratio is lower than that possible in hydropulping machine type operations (water:solids is typically 20:1 to 33:1) or at a certain moisture content. The main advantage is that used paper or board can be defibrillated at any time.

When processing air-dried feedstocks, the choice of water added to the digester is determined by the intended use of the dissociated fibers.

If the fiber is to be used for paper or paperboard production by conventional means, it is advantageous to saturate the digester contents with water. However, if the fibers are to be used essentially for dry forming operations, fibrillation of the recovered paper or paperboard in the air-dry state yields a vertical, fluffy fibrous mass.
Example 2 The role of the turbulence propeller in the transfer line is illustrated by the following example relating to a recovered corrugated paper weave.

The diameter of the transfer line used in the examples was 51 skin.

This can be contracted to the 9.5 diameter side by ironing an annular chiyoke with a sharp edge to the iso. The results are shown in Table 2. Both examples had a float of 0, water:used paper solids ratio = 11.0:1, and an applied gas pressure of 4.83 MPa.
It was held in The corrugated paper was allowed to submerge for 3 minutes under the above gas pressure and the digester outlet valve was opened. Table 2 Effect of constricting the moving line 9.5 Side diameter chokes increase the turbulence of the flow during the moving period.

Therefore, it increases the force acting on the ejecting used paper. This results in increased fibrillation compared to the non-choked embodiment. Example 3 Many of the foreign substances in contaminated used paper have high temperature lubricity.

Therefore, when the method of the present invention is applied to contaminated waste paper or paperboard and sufficient water is added to the digester to immerse the recovered material, the next pressurized bond period will be untreated. Significantly weakens the structure of used paper or paperboard, but has minimal effect on foreign objects. During the next transfer step, the forces introduced by the turbulent flow considerably scale and fiber the water-saturated used paper, while leaving foreign objects relatively unaffected. Table 3 shows the effectiveness of used paper or paperboard contaminated by the method of the invention. Sufficient water is added to immerse the feedstock, the digester is sealed, and the 4.83M
Pressurize to Pa. The digester contents were clarified for 2 minutes under applied gas pressure. Then open the digester outlet valve. The digester contents were not heated and the process was carried out at an ambient temperature of 18 oo. From Table 3, most of the foreign substances are not affected by the rapid release from the digestive system.

Foreign matter and dissociated fibers can be easily separated by a simple sorting operation. Table 3 Sensitivity of various materials when subjected to the process of the invention When compared with hydropulping machines, the process of the invention has the advantage of obtaining a minimal dispersion of asphalt, adhesives, waxes and other bituminous substances. .

These remain combined with foreign substances, but are removed during the next product sorting. Therefore, the present invention can be used to effectively treat feedstocks contaminated with more pitumen than would be tolerated for hydropulp type processing. Example 4 The principle of selective disassembly can also be applied to the separation of mixed used paper stock.

Composite carton boards, such as corrugated boxboard, are manufactured from different quality materials.

Therefore, in this boxboard, the corrugated synthetic fibers in the core of the board are generally rich in neutral sulfite pulp, while the outer liner pleats are rich in relatively strong kraft pulp. When the carton board is saturated with water according to the method of the invention and the saturated board is rapidly discharged from the digester, different components of the corrugated boxboard exhibit different responses to discharge. Under conditions of incomplete defibration, a relatively keyed corrugated paper is more easily defibrated than a relatively strong externally pleated paper.

When screening partially defibrated products, the material passing through the screen provides a stream rich in relatively strong kraft fibers, while the screened material is rich in relatively weak sulfite pulp. Table 4A shows the results of treating corrugated boxboard according to the method of the invention.

This box board was filled with 12.7 parts of water per weight into the fire extinguisher, the fire extinguisher was sealed, and nitrogen gas was added to
3 MPa), and the pressurized board is immersed and released for 3 minutes. The discharged product is screened on a 0.25 rib slotted screen, separated into over-screen and under-screen fractions and collected. The fractions larger than the size are further defibrated in the Rokuazusa tank scale fiber machine, and after the fiber dissociation is completed, the paper-making properties of the two fractions are evaluated by the Appita standard method. As can be seen from the Table, the higher the fraction of kraft fibers above the screen size reflects the higher paper-making power of that fraction.

Table 4A Separation of corrugated boxboard by the method of the invention (
Digester operating temperature = 18 °C) The present method is not limited to separating components from composite carton boards, where the fractions of the mixture have different sensitivities to the turbulence associated with digester discharge. Can be applied to all mixtures of paper or paperboard.

The method of the invention is also not limited to the treatment of wet or damp paper or paperboard, but can also be applied to dry raw materials.

The table is made of kraft wrapping paper and newspaper 50/5. %
The results are shown when the mixture was processed under air dry conditions and without adding water to the digester.

The digester was pressurized to 4.83 Mpa at ambient temperature and discharged the spent paper mixture. This process was repeated for three releases, after which the product was screened. The fractions below the screen size and the fractions above the screen size were fractionated and collected, moistened again with water and evaluated for paper manufacturing properties by the Appita standard method. Table 4B Since kraft wrapping paper defibrillates more easily and is thicker than newspaper, this is reflected in the higher strength properties of the screen size and above fractions.

Example 5 When operated at ambient temperature, the process of the invention is insufficient for the total defibration of hot, cloudy, strong papers.

However, at elevated temperatures, the method of the present invention can defibrillate high-temperature high-strength paper. Table 5 shows high temperatures; defibrillation of high-strength kraft bag paper; The results are shown below.

In a first embodiment, the paper is placed in a digester with enough soda to cover it and the digester is heated from ambient temperature to 120 DEG C. in 8 minutes. The device contents were then held at 120q0 for an additional 5 minutes and discharged. The applied gas pressure was 2.01 MPa. The second example was processed similarly to the first example except that water rather than caustic soda was charged into the digester.
Table 5: When high-humidity strong back kraft paper was defibrated using 1 female/1 caustic soda, it was completely defibrated,
When water was used, 99% defibration was achieved.

Example 6 The problem in defibrating used paper and paperboard is the total defibration of dry pulp.

Rewetting of beletized pulp (where the pulp is provided as pellets approximately 1 m in diameter and 25 sides long) is particularly difficult.

If residual black liquor remains in the pulp as a result of insufficient pulp washing, this will tend to act as a binder in the dried pulp and prevent rewetting of the pulp. In this condition, rewetting of the pellets takes several hours in a hydropulp type device. The method of the invention can also be used to facilitate cleaning of pulp pellets and the like. Under the operating conditions shown in Table 6, it was possible to completely defibrillate neutral sulfite pulp pellets made from eucalyptus wood without using any chemicals. Table 6 Example 7 Another embodiment of the method of the invention is the removal of pigment, clay and starch particles from used paper and bulk board.

The dissociation of ink particles and other coatings from the recovered material proceeds simultaneously with the overall defibration of the recovered material. Dissociated ink particles and other coatings are then removed by washing according to known techniques. When recovered paper and paperboard are defibrillated in the presence of elevated sewage water, some ink and coating dissociation occurs.

Table 7A shows the results of treating newspaper with water at various temperatures.

Sufficient water is added to the digester to thicken the newspaper;4.
Pressurize with nitrogen gas to 83 MPa and then heat the digester contents to a predetermined temperature. As soon as the temperature reaches a predetermined temperature, the contents are released to atmospheric pressure. The pulp thus produced is washed on a vibrating screen to remove all dissociated ink. The pulp is made into handsheets by Appita's standard method. Ellejo (E) using a green filter
Gloss was measured by photometa (Irepho). A control sample was prepared by further defibrillation of a newspaper sample in a British standard digester.

As seen in Figure 7A, the gloss of the pulp product progressively decreased as the cooking temperature was increased to 130 oo or above. This is due to the gradual enrichment of lignin, 20
The gloss of the product decreases more and more until the pulp gloss decreases to 26.7% at 0oo. No. 7A Temperature influence on ink removal from newspaper removal is performed.

Particularly bright pulps can be obtained if hydrogen peroxide is also added to the liquor.

Table 7B shows the results of carrying out the method of the invention using alkaline liquids.

The cooking and pulping techniques are the same as described above in this example. 7th. IB Surface Deinking of Newspaper Using Alkaline Liquid Next, preferred specific examples falling within the technical scope of the present invention will be enumerated.

1 Defibration of paper and similar cellulose-containing materials involves the steps of subjecting said cellulose-containing material to a high-pressure environment, rapidly transferring said material under turbulent conditions to a low-pressure environment, and removing cellulose from the produced product stream. A method for recycling paper products, comprising a step of separating fibers.

2. The method according to 1 above, wherein the cellulose-containing material is uniformly saturated with water or liquid before being subjected to the high pressure environment.

3. The method according to 2 above, wherein the liquid is an aqueous solution containing one or more components selected from the group consisting of alkali, alkaline reaction salt, bleached and surfactant.

4. The method according to 2 above, wherein the saturated cellulose-containing material is heated before or simultaneously with being subjected to the high pressure environment.

5. 1 or 2 above, wherein the high-pressure environment is a closed system pressurized with a gas selected from the group consisting of nitrogen gas, carbon dioxide, halocarbon, hydrocarbon, halohydrocarbon, particle-free low-oxygen fuel gas, and air. Method described.

6. The method of claim 2, wherein said saturated cellulose-containing material is subjected to a high pressure environment for a period of up to about 5 minutes.

7. Rapidly transferring the material from the high pressure environment to the low pressure environment by rapidly opening a transfer line located between the two environments and configured to reliably apply a separating force and a tensile force to the passage of the material. The device according to 1 or 2 above.

8. Atsushi's method for separating the product stream into lower and upper flow fractions containing plexus and relatively tough cellulose, respectively.

9. The method of item 2 above, wherein the product stream is washed to remove the coating and then sorted to separate the cellulose fibers.

10. The method according to 1 or 2 above, wherein the product stream is sorted to separate the fibers from foreign matter or unsardine fiber material.

11 Cellulose fibers produced according to the above method.

12 Essentially the same method as depicted in the drawings.

13 Essentially the same method as described in Examples.

14 Cellulose fibers produced as described in Examples

[Brief explanation of the drawing]

The drawing shows a wall sheet of a system for carrying out the method of the invention. 1...Recovered cellulose fiber-containing material inlet, 2.
... Glass and metal removal equipment, 3... Cutting machine, 4,
5... Valve, 6... Water or liquid tank, 7... Chemical and/or water inlet, 8, 10... Valve, 9...
Compressed gas tank, 11... Finishing gas inlet, 12...
- Digestion device, 13... Steam inlet, 14, 15... Valve, 16... Cyclone, 17... Gas outlet, 18... Stock tank, 19... Water inlet, 20, 21... Valve,
22...Secondary treatment, 23...Pulp outlet.

Claims (1)

[Claims] 1 Defibration of paper and similar cellulose-containing materials involves the steps of subjecting said cellulose-containing material to a high-pressure environment, rapidly transferring said material under turbulent conditions to a low-pressure environment, and removing cellulose from the produced product stream. A method for recycling paper products, comprising a step of separating fibers.