WO2025111676A1 - Method for recycling paper money or special paper, fibrous suspension, recycled fibre, use of same, and paper obtained - Google Patents

Abstract

The present invention pertains to the fields of recovery or reuse of waste materials. The present invention discloses a method for recycling banknotes. The process of producing banknotes generates solid waste, such as paper rejected due to quality problems and printing defects, resulting in a considerable amount of waste that must be managed properly. The present invention aims to overcome the aforementioned problem and proposes a method for recycling current paper money on the basis of its composition. In this way, the recycling of scraps from the banknote manufacturing process highlights the relevance of the circular economy and the responsible use of resources in the printing industry.

Description

RECYCLING PROCESS OF PAPER MONEY OR SPECIAL PAPER, FIBROUS SUSPENSION, RECYCLED FIBER AND USE OF THE SAME AND PAPER OBTAINED

FIELD OF APPLICATION

The present invention applies to the fields of recovery or utilization of waste materials. The present invention discloses a process for recycling waste material from the banknote production process.

FUNDAMENTALS OF THE INVENTION

Recycling scraps from the banknote production process and/or paper money recycling is a fundamental practice in the sustainable management of waste generated by banknote printing companies. The banknote production process normally generates solid waste from printed or unprinted paper rejects due to quality problems, paper rejected for printing adjustments, possible paper from printer jams, refills from the process of cutting sheets until the final format of the banknotes is correct, and also printed banknotes rejected due to possible printing errors or any other unacceptable defects. To deal with this waste, they are duly shredded (scraps) in special machines at the printing companies to de-characterize them in order to avoid any improper use of the material after it is destined for disposal or recycling.

These paper scraps can play a crucial role in reducing waste and promoting sustainability. For example, they can be recycled, which allows them to be used as a source of fiber in the manufacture of high-quality papers. This practice not only helps to minimize the environmental impact by reducing the amount of waste sent to landfills, but also contributes to the preservation of natural resources, as it avoids the need to produce paper from virgin raw materials. In this context, in order to solve the problem explained above, the present invention provides a process for recycling current paper money, based on its composition. In this way, recycling scraps from the banknote production process illustrates the importance of the circular economy and the responsible use of resources in the printing industry. STATE OF THE ART

Document PI 9605508-1 reveals the development of a technology that enables the recycling of papers containing chemical additives based on formaldehyde-melamine, a product commonly known as wet strength. Such papers, in this case currency papers, are currently incinerated or deposited in landfills and sanitary landfills, as there is no national technology that allows them to be reused by the recycling industry. This causes environmental and ecological problems, as such material does not decompose or dissolve in water, remaining intact in the soil, releasing printing ink and pollutants. In order to enable the recycling of such material, this technology was developed that enables the reuse of papers impregnated with formaldehyde-melamine. To this end, alkalis are used together, products that act on the chemical bonds of formaldehyde-melamine.

Unlike what is reported in the document above, current paper money uses epichlorohydrin resin as its UR principle. The disuse of urea resin for this purpose is linked to its high toxicity. Although this product has historically been used in the manufacture of paper to provide moisture resistance, this substance, which belongs to the formaldehyde resin family, is known for its strong and unpleasant odor, as well as its toxic nature. With the change in chemical agent, the mass works in a neutral medium, in the pH range of 7. In the present invention, there is no need for the mass to be immersed and the process of the present invention occurs for a period of up to 6 hours and with controlled pressure.

Document CN109294034 reveals a method for transforming waste banknotes into recycled composite material. The method comprises the following steps: Step 1. Pretreat the waste banknotes and confidential waste paper to optimize the fiber structure and morphology to obtain pre-modified fibers; Step 2. Weigh in parts by weight: 30-50 parts of pre-modified fiber, 52-67 parts of recycled polyethylene particles, 1-3 parts of maleic anhydride grafted polyethylene, 0.5-1 parts of polyethylene wax, 0.1-0.2 parts of light stabilizer, 0.1-0.2 parts of antioxidant 168; Step 3. The pre-modified fiber and recycled polyethylene granules weighed in step 2 are placed in a high-speed mixer, mixed well, and then maleic anhydride grafted polyethylene, polyethylene wax, light stabilizer and antioxidant are added sequentially. Mix the antioxidant 168 to obtain a mixture I, and add the mixture I to the twin-screw flat extruder from the main feeding port in a uniform feeding manner, and extrude the granules for sealing; Step 4. The extruded pellet obtained in step 3 is injection molded by an injection molding machine, and then demolded and cooled to obtain a composite material.

Unlike the present invention, the document above reports the transformation of paper scraps with RU as part of a polymeric material, which will serve as raw material for the extruder.

Document BR 10 2019 003165 4 describes the production of polymer composites based on polypropylene and banknotes (banknotes referring to any currency) for the manufacture of objects made of polypropylene as the main material. The polypropylene used can be virgin and/or recycled. Blends of polypropylene and other polyolefins are also considered, aiming to provide a viable alternative to significantly reduce the accumulation of this waste. This technology has enabled an efficient method for recovering waste banknotes unsuitable for circulation based on the production of composites containing polypropylene, without the need for prior treatment of the note and impregnation. with resins. The choice of polypropylene is related to its wide industrial use, due to the diversity of items produced based on this polymer. For this technology, the installed capacity to produce the same items made of all types of polypropylene was used, using the composite produced with virgin polypropylene and/or recycled with banknotes. From the composite produced, it is possible to mold items used in the automotive and packaging industries, to manufacture toys, furniture, among others.

Unlike the present invention, the document above reports the reuse of paper money as an integral material of a polymeric compound aimed at the manufacture of new objects.

SUMMARY OF THE INVENTION

The banknote production process generates solid waste, such as paper rejected due to quality issues and printing errors, resulting in a considerable amount of waste that needs to be managed properly.

In this scenario, aiming to solve the aforementioned problem, the present invention offers a current paper money recycling process, based on its composition. In this way, the recycling of scraps from the banknote manufacturing process highlights the relevance of the circular economy, the responsible use of resources in the printing industry, the reduction of the consumption of virgin fibers in paper production and the reduction of the volume of waste destined for landfills.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 illustrates the simplified flowchart of the process covering step (c);

Figure 2 illustrates the material to be recycled;

Figures 3 and 4 illustrate the final product obtained in step (c).

DETAILED DESCRIPTION OF THE INVENTION

The invention can be better understood through the following detailed description, in line with the attached figures.

As illustrated in part of Figure 1, the present invention discloses a process for recycling special or security paper, comprising the steps of:

(a) Perform thermal and chemical treatment of the material to be recycled by pressure cooking; and

(b) Wash the material.

Special or security paper is defined as: paper money, wine labels, abrasive paper, passport, decorative paper, stamps, official documents, among others, which contain wet-resistant resin (RU).

The material to be recycled is special or security paper, preferably with a 100% cotton composition by weight and a resin with wet strength (WW) greater than 0.25% of the final paper (1000 kg cotton paper / 2.50 kg resin), such as residual materials from the production of banknotes or from any other source, such as notes withdrawn from circulation on the market, without the need for prior cleaning. In addition, the size of the material to be used in the process can be variable; preferably, it is suggested to use perforated material, as illustrated in Figure 2, since the larger the contact area, the greater the favoring of the chemical reactions present here; however, size is not an impediment.

The process is carried out in batches, so in step (a), the material is weighed, for example, 1000 kg or 2000 kg, depending on the equipment used in the process. The material is subjected to thermal and chemical treatment aimed at breaking it down into reusable fibers, breaking down the original wet strength of the special or security paper, dissolving the polyester-based security threads, for example, and dispersing the various inks, metallic pigments, resins and varnishes used in the banknote printing process.

Thermal and chemical treatment is carried out in equipment that perform agitation at the time of cooking, for example, spherical or cylindrical rotary digesters or autoclaves. Preferably, these equipments are built in carbon steel coated externally with insulating material for better heat exchange, avoiding thermodynamic losses.

For example, the capacity for a spherical digester with a volume of 10.8 ^m3 is 1000 kg of material per batch and for a cylindrical digester with a volume of 23 ^m3 it is 2000 kg per batch.

The material to be recycled is dosed with water and an alkaline agent, preferably caustic soda. The concentration of the alkaline agent used is 48.5% to 50.5% by weight, preferably 50% by weight. The proportions used in the process include a load of 2 parts of water and 0.1 part of alkaline agent for 1 part of material to be recycled (volume/weight), for example, for every 2000 L of water, 1000 kg of material to be recycled and 100 L of alkaline agent are used. The quality of the water to be used is invariable, being possible, for example, the use of industrial water, which includes a color standard > 30 uc and turbidity > 2.0 ntu. After feeding the equipment with the material to be recycled, water and the alkaline agent solution, it is hermetically sealed to begin the pressure cooking process.

The internal pressure of the equipment is raised from 4.3 to 4.7 bar and controlled by introducing saturated steam from, for example, a boiler in the company's utilities area.

A movement, preferably rotational, is applied with the aim of homogenizing the material during the process, making the chemicals interact uniformly with the shavings being treated.

Once the material has been cooked, which can last up to 7 hours, the pressure in the equipment is gradually released, for example up to 3 hours, until atmospheric pressure (1 atm = 101325 Pa) is reached through relief valves. Once the cooking equipment is depressurized, it is opened using the hermetic lid and the treated material is transferred to a tank. where it will be fed to the next stage, washing the material.

In step (b), the material is washed to reduce the pH of the medium, preferably under moderate agitation. The washing is carried out by adding water with a pH close to 7 to the tank and leaving the recently cooked material from step (a) to soak in the equipment for an average time of 3 hours. Optionally, aluminum sulfate 11 - 12% m/m and pH 3.0 in a 1% solution can be added, in a proportion of 0.02 parts of aluminum sulfate to 1 part of recycled material (volume/mass), to speed up the washing due to the reduction in pH. Subsequently, the water is removed and new water is added to the washing tank. Throughout the washing, the pH of the suspension is controlled; when values between 7.0 and 8.0 are reached, the process is finished, thus obtaining a fibrous suspension with a neutral pH that can be used to produce any product that uses this raw material, in the production of paper and any other product of fibrous origin.

The fibrous suspension obtained from the process comprises neutral pH between 7.0 to 8.0 and 50% in water.

In order to produce special paper, an additional step can be implemented in the process, which is the extraction of water, step (c). This extraction facilitates the use of the fibrous suspension in the paper production process.

In step (c) the extraction of water from the material after washing is carried out by removing water from the fibrous suspension by means of gravity drainage on a forming screen, for example made of polyester, and subsequently the material is pressed, for example with pneumatic pressure of between 3 - 4 bar, and, preferably, with a wet press up to a value of up to 50% moisture in the recycled material.

Optionally, the wet press can be lined with felt.

This process does not remove the color entirely from the base material used, as the resulting fibers still contain a certain amount of particles from pigments, security threads, etc. The total process loss is estimated at approximately 10% of the original quantity of banknote trimmings initially purchased.

At the end of step (c), a recycled fiber is obtained that can be used in the production of paper and any other product of fibrous origin, as illustrated in figures 3 and 4.

The fiber obtained from the process with the addition of step (c) has a pH between 7.0 and 8.0, an average moisture content of 10% to 50% and a light and opaque color.

In this way, the special paper obtained from the process of the present invention can be carried out directly from step (b) with the fibrous suspension or from the fiber obtained after step (c).

The fibrous suspension, as well as the fiber obtained from the process, can be used to manufacture paper or any other product of fibrous origin, such as packaging, hygienic mats, acoustic insulation, among others.

In this way, any paper product or any other product of fibrous origin can be produced, such as special paper, banknotes, passports and tax stamps, comprising among one of its constituents the fibrous suspension or fiber as obtained by the process of the present invention.

As can be seen, the present invention enables the circular economy of a product, waste from banknotes, which until now has not been possible to use for the production of the base product: paper. In this way, there is less dependence on virgin raw material and a renewable input option of great value in the paper market is gained, which is cotton fiber.

The invention will be elucidated by the following examples, without being limited to or by them.

Examples

Example 1: Obtaining recycled special paper with fiber obtained from additional step (c) To obtain special recycled paper, the fiber obtained in step (c) undergoes a disintegration of the fibrous raw materials. That is, the material passes through a tank equipped with rotating blades that disintegrate the fed material. The process is carried out at a consistency (mass/mass concentration) of approximately 5%, that is, 5% consistency means that there is a ratio of 5 g of fibrous material (solid) to 100 g of water (liquid).

This disaggregated mass then passes through rotating blades that modify the fibers appropriately for paper production, with optional controls: inlet and outlet pressure at 2.5 to 4.0 Pa, electrical current of the equipment, which must be constant, and Schopper degree (°SR - unit of measurement referring to the degree of drainage of a fibrous suspension) according to the desired specification for the final paper.

This refined pulp goes to a tank where it receives additives such as dyes and bleaches, in continuous dosage such as glue, starch, retainers, coagulants, mineral filler, among others according to what is desired to be customized in the final product. The refined pulp is purified to eliminate part of the impurities in various centrifugal purifiers and fed through a distributor to the inlet box of the paper machine and then goes to the tank that feeds the paper machine.

The headbox distributes this fibrous suspension through a dosing lip on the flat table (Fourdrinier) whose function is to form the paper by draining it onto a perforated plastic screen. At the end of this stage, the continuous sheet of paper has a dry content of approximately 20%.

After this sheet passes through presses equipped with felts to absorb the water removed by this pressure until a dry content of approximately 40%.

The sheet is then dried using steam-heated cylinders until the product reaches its final moisture content of approximately 5%.

In the middle of the drying process, the web may receive a surface bath treatment (usually a modified starch) to improvement of some paper properties in a dosing equipment called a glue press or size press.

After this treatment, the paper is dried again using steam-heated cylinders or infrared dryers.

Some papers also receive mechanical treatment using heated steel or rubber-coated calenders to improve the uniformity of the paper surface (smoothness, roughness), as well as to partially adjust the thickness of the product.

The paper is then rolled onto spools and removed from the paper machine.

These rolls, called jumbo rolls, are destined for a finishing equipment called a rewinder where these rolls are wound under tension and cut to the required width into coils.

These coils can then be packaged for their destination and sale or go through cutters where they are cut into sheets and then packaged for sale.

The present invention has been disclosed in this descriptive report in terms of its preferred embodiment. However, other modifications and variations are possible from the present description, and are still within the scope of the invention disclosed herein.

Claims

1. Special or security paper recycling process, CHARACTERIZED by comprising the steps of: (a) carry out thermal and chemical treatment of the material to be recycled by pressure cooking; and (b) wash the material. 2. Process, according to claim 1, CHARACTERIZED in that the material to be recycled is special or security paper, preferably with a composition of 100% by weight of cotton and a resin participation with wet strength (RU) greater than a participation of 0.25% on the paper. 3. Process, according to claim 1 or 2, CHARACTERIZED by the size of the material to be used in the process being variable, preferably, the material being perforated. 4. Process according to any one of claims 1 to 3, CHARACTERIZED by occurring in batch, in which, in step (a), the material to be recycled is subjected to thermal and chemical treatment in equipment that performs agitation at the time of cooking, in which the material to be recycled is dosed with water and an alkaline agent, in which the concentration used of the alkaline agent is 48.5% to 50.5% by weight; the proportions comprising a load of 2 parts of water and 0.1 part of alkaline agent for 1 part of material to be recycled (volume/weight); where, after feeding the equipment with the material to be recycled, water and alkaline agent solution, it is hermetically sealed to begin the pressure cooking process, where the internal pressure is increased from 4.3 to 4.7 bar and controlled with the introduction of saturated steam; Once the material has finished cooking, the pressure in the equipment is gradually released to atmospheric pressure to open the hermetic lid and the treated material is transferred to a tank. 5. Process, according to claim 4, CHARACTERIZED due to the fact that the equipment that performs agitation during cooking is a spherical or cylindrical rotary digester or autoclave and is made of carbon steel and coated externally with insulating material. 6. Process, according to any one of claims 1 to 5, CHARACTERIZED in that, in step (b), the washing of the material is under agitation; where the washing takes place by inserting water with a pH close to 7 into the tank and leaving the recently cooked material, coming from step (a), to soak for 3h; subsequently, the water is removed and new water is inserted into the washing tank; throughout the washing, the pH of the suspension is controlled, when values between 7.0 and 8.0 are reached, the process is finalized, obtaining a fibrous suspension. 7. Process, according to claim 6, CHARACTERIZED by further comprising the addition of aluminum sulfate 11 - 12% m/m and pH 3.0 to a 1% solution, in a proportion of 0.02 parts of aluminum sulfate to 1 part of recycled material (volume/mass). 8. Process, according to claim 6, CHARACTERIZED by further comprising a step (c) to produce special paper, which is the extraction of water, carried out by means of the removal of water from the fibrous suspension by means of gravity dewatering in a forming screen and, subsequently, the material is pressed, preferably, with a wet press to a value of up to 10% humidity. 9. Process, according to claim 8, CHARACTERIZED in that the wet press is additionally coated with felt. 10. Fibrous suspension CHARACTERIZED by being obtained by the process, as defined in claim 1, comprising neutral pH between 7.0 to 8.0 and 50% in water. 11. Recycled fiber CHARACTERIZED by being obtained from the extraction of water from the fibrous suspension, as defined in claim 10, comprising pH between 7.0 to 8.0, average moisture content of 10% to 50% and light and opaque color. 12. Use of fibrous suspension, as defined in claim 10, CHARACTERIZED by being for the production of paper or a product of fibrous origin. 13. Use of recycled fiber, as defined in claim 11, CHARACTERIZED by being for the production of paper or a product of fibrous origin. 14. Paper or product of fibrous origin CHARACTERIZED by comprising fibrous suspension, as defined in claim 10, or recycled fiber, as defined in claim 11.