Block made of paper and cardboard-derived material and its production method

Abstract

The invention relates to sheets and their production methods, which are used as protective packaging in the assembly, transportation, fastening, and support of products or materials manufactured in industrial sectors. The sheets subject to the invention are made from recycled materials and are produced from laminated paper and cardboard derivatives bonded together with adhesive.

Description

[0001] DESCRIPTION

[0002] BLOCK MADE OF PAPER AND CARDBOARD-DERIVED MATERIAL AND ITS

[0003] PRODUCTION METHOD

[0004] Technical Field

[0005] The invention relates to sheets with a thickness of at least 5 mm made from recycled material and the associated products, as well as the production method thereof.

[0006] State of Art

[0007] Today, wood and wood-based products are widely used in various fields, either directly as solid wood or in composite forms such as pressed composite coatings, particleboard, fiberboard, and similar materials.

[0008] One such product is blocks. Blocks are commonly produced from materials such as wood, chipboard, plywood, MDF, and plastic to ensure balanced and protected logistics for stacking or supporting products or materials on floors in all industrial sectors.

[0009] However, each material choice presents different issues. For instance, wood decays and deforms in humid environments. Additionally, wood and plastic are disadvantaged in terms of strength. These disadvantages often lead to balance issues and occupational accidents after products or materials are stacked.

[0010] Moreover, the use of these products poses risks such as mold, bacteria, fungi, oxidation, worm infestation, insect attacks, resin leakage, and splinters, creating hygiene concerns that can harm human and environmental health. Furthermore, due to the structure of wood-based blocks, there is a risk of combustion in fire situations, which may exacerbate the fire

[0011] For these reasons, studies have been conducted to develop blocks made from new materials.

[0012] In the current state of the art, studies on paper-based blocks exist.

[0013] For example, US2010062233A1 discloses a method for producing a block from paper. The proposed method involves using waste paper. The waste paper is used without undergoing any additional processes other than shredding. Adhesive is applied to the shredded paper, and the pieces are then joined to form a panel. Panels with a thickness ranging from 6.53 mm to 2.54 cm are produced using this method. However, the panels produced using this method cannot achieve sufficient strength, resulting in plates of inadequate thickness. During cutting and use, gaps and separations occur between laminations. Additionally, due to the use of adhesive between the laminations, the panels may bend under weight. These issues prevent paper-based blocks from being widely used, despite the utilization of paper and cardboard waste.

[0014] Investigations and research have revealed that the technical issues associated with paper-based blocks, particularly in the current state of the art, and the inadequacy of existing solutions have made it necessary to develop advancements in this technical field.

[0015] Brief Description and Objectives of the Invention

[0016] The main objective of this invention is to introduce a sheet structure and its production method. The sheet is made from multilayered, recycled paper and cardboard-derived raw materials, ensuring sufficient strength, resistance to bending, and durability, without experiencing any separation or disintegration during use.

[0017] To achieve the above advantages, the production method involves the use of multiple layers of recycled paper or cardboard with a rough and porous surface. These layers are coated on at least one side with a starch-based adhesive that has a surface density of 40-60 g / m2The layers are stacked in a lamination station, and the stacked layers are then pressed with a pressure ranging from 50 to 200 bars for a duration of 0.5 to 15 minutes. This process allows the adhesive to partially penetrate the layers and eliminates or reduces the surface roughness, forming blocks. To create a sheet with a thickness of at least 5 mm, multiple blocks are coated on at least one side with adhesive at a surface density of 40-60 g / m2and are placed on top of each other. The stacked blocks are then pressed under a pressure of 50 to 150 bars for a duration of 0.5 to 10 hours, resulting in the final sheet.

[0018] By utilizing the rough and porous structure of recycled paper in this production process, the use of a higher volume of adhesive is made possible. The appropriate adhesive selection, combined with the application of specific pressure values and the segmented block-by-block production method, allows for the production of sheets from paper or cardboard with a thickness exceeding 5 mm. This results in a high-strength sheet. This solution also offers environmental advantages due to the use of recycled paper, making it more eco-friendly than its alternatives. Additionally, the use of natural adhesives eliminates the need for drying ovens. The pressure values used in this method also expel a portion of the oxygen from the adhesive and layers, making the sheet more resistant to ignition.

[0019] The resulting sheet demonstrates improved sound and heat insulation performance compared to alternative products. Its surface can be polished, painted, or treated with plaster or mortar, enabling its use in a variety of applications.

[0020] In a preferred embodiment of the invention, the adhesive is mixed with borax before application, imparting flame-retardant properties to the sheet and preventing the growth of fungi and other microorganisms over time. The sheet can also be shaped as desired during the production process, particularly during the sizing and cutting stages. It can be manufactured and used in various three-dimensional geometric shapes and sizes, such as cylinders, pyramids, or cubes.

[0021] Reducing operational costs and raw material expenses while protecting nature are also among the objectives of this invention.

[0022] Description of the Figures of the Invention

[0023] To better understand the subject of the invention, the necessary figures and their corresponding explanations are provided below:

[0024] Figure 1: A view of a layer.

[0025] Figure 2: A view of a block formed from laminations.

[0026] Figure 3: A view of a sheet formed from blocks.

[0027] Figure 4: A flow diagram of the production process for the sheet, the subject of the invention.

[0028] Figure 5: A schematic sectional view before and after pressing.

[0029] Figure 6: A microscopic image showing the surface of recycled paper.

[0030] Figure 7: Light transmittance graph for Sample 1.

[0031] Figure 8: Light transmittance graph for Sample 2.

[0032] Figure 9: Light transmittance graph for Sample 3.

[0033] Figure 10: Specific optical density graph for Sample 1.

[0034] Figure 11: Specific optical density graph for Sample 2.

[0035] Figure 12: Specific optical density graph for Sample 3. Reference Numbers

[0036] The parts and components shown in the figures are numbered to enhance understanding of the subject of the invention:

[0037] 10: Layer

[0038] 101: Layer surface

[0039] 11: Block

[0040] 111: Block surface

[0041] 12: Sheet

[0042] 13: Layers before press

[0043] 14: Layers after press

[0044] 15: Adhesive molecules

[0045] 20: Lamination

[0046] 30: Press

[0047] 40: Secondary press

[0048] 50: Sizing

[0049] 60: Optional processes

[0050] Detailed Description of the Invention

[0051] As shown in Figure 1, layers (10) made from recycled paper and / or cardboard are used in the production process of a sheet (12). The flow diagram of this process is represented in Figure 4.

[0052] The term "recycled paper / cardboard" here refers to paper or cardboard that has undergone a recycling process, which results in altered surface characteristics, including higher porosity and roughness, as compared to used paper. Preferably, used paper / cardboard does not undergo processes such as de-inking, coating, or calendaring during recycling, as these processes reduce porosity and roughness values.

[0053] The porosity value of recycled paper depends on the paper / cardboard's type, fiber quality, and production process. Porosity measures the ease with which air or liquids pass through the paper and is expressed in units such as cm3 / (min cm2) (Bendtsen method). Preferably, the porosity of the recycled paper used in the current method is between 100-3000 mL / min, and particularly between 500-3000 mL / min. A higher porosity value enhances the technical benefits of the process. The surface roughness value of recycled paper / cardboard is measured using a stylus profilometer. A profilometer is a device that uses a fine-tipped pen to trace the surface and record vertical deviations, thereby measuring the roughness or texture of the surface. In the preferred embodiment of the invention, the surface roughness value of recycled paper / cardboard, as measured by the stylus profdometer, ranges between 3 pm and 10 pm. Paper / cardboard with higher roughness values offers greater technical advantages.

[0054] First, the layers (10) are cut and sized according to the desired dimensions. Subsequently, the sized layers (10) undergo a lamination (20) process. In the first step of the lamination (20) process, adhesive is applied to the layer surfaces (101). The adhesive is applied to one side or both sides of each layer (10) at a surface density of 40-60 g / m2The adhesive used can be a polyvinyl alcohol (PVA)-based adhesive or a starch-based adhesive. The starch-based adhesive may be selected from dextrin, hydroxyethyl starch, or carboxymethyl starch. Dextrin is particularly preferred as a starch-based adhesive because it forms hydrogen bonds with the cellulose fibers present in the structure of the layers (10). Preferably, the adhesive is applied to one surface (101) of the layers (10), ensuring that adhesive is present between the stacked layers, as illustrated in Figure 2, forming a block (11).

[0055] In the production of the sheet (12) subject to the invention, paper / cardboard waste with irregularly arranged cellulose fibers, resulting in a rough surface, is used. The surfaces of these recycled paper / cardboard layers (10) are rough, providing a larger surface area for the layers (10). This increased surface area allows for a greater application area for the starch-based adhesive and expands the contact surfaces between the layers (10). The increased contact and friction between the layers (10) ensure that they adhere more effectively to each other.

[0056] Adhesive application can be performed using rollers or anilox rollers. In the lamination (20) station, adhesive-coated layers (10) are stacked so that the surface (101) of each layer (10) comes into contact with the surface (101) of another layer (10). Subsequently, blank layers (10) are placed on top of the adhesive-coated layers (10), preventing the adhesion of layer groups to one another. Preferably, the stacked layers (10) consist of 2-5 layers (10).

[0057] Another characteristic of the recycled paper / cardboard layers (10) is their porous structure. The layers (10) are porous throughout their volume, allowing the adhesive applied to the layer surfaces (101) to diffuse throughout the layer (10). This property ensures that the adhesive dries more slowly during the lamination process until the desired primary block (11) thickness is achieved. As a result, problems such as rapid drying and inability to form a block (11) are mitigated.

[0058] The stacked layers (10) are then transferred to the pressing section (30). In the pressing section (30), a heated conveyor, preferably operating at an operational temperature of 70-120 °C, is used for transporting and pressing the stacked layers (10), with pressure applied from the upper part of the conveyor. This method enables a shorter application time in the pressing section (30). If pressing is performed using a system with a heated conveyor, the application time is reduced by approximately 20%. In the pressing section (30), a pressure ranging from 50 to 200 bars is applied to the stacked layers (10) for 0.5-15 minutes, depending on their thickness. Preferably, the pressing environment temperature is 17-26 °C.

[0059] Pressing can also be performed using a press machine or by placing a weight that provides the specified pressure range. The pressing section (30) ensures the uniform distribution of the adhesive between the layers (10) and facilitates the release of trapped air within the adhesive. This prevents potential deformities caused by trapped air, such as wrinkles on the surfaces of the layers (10), minimizing and preventing these issues. Moreover, the release of air contributes to the fire-retardant properties of the final product, the sheet (12). As a result of the pressing process, a block (11) is obtained, with a thickness greater than 5 mm.

[0060] Referring to Figures 5 and 6, pressing causes the adhesive to diffuse through the pores of the layers. This eliminates the air pockets in the pores of the layer structure (10). Additionally, the rough structure of the layers (10) is smoothed during pressing, resulting in a smooth block surface (111).

[0061] The obtained block (11) has a dense structure that further restricts air diffusion. The absence of air within the block (11) enhances its fire-retardant properties.

[0062] For producing sheets (12) with a thickness of 5-20 mm, a pressure of 39-59 bars must be applied in the pressing section (30). Similarly, for thicknesses of 21-30 mm, 59-79 bars are applied; for 31-50 mm, 79-98 bars; and for sheets thicker than 51 mm, 98-138 bars. The pressing durations corresponding to these thickness and pressure ranges are determined as 0.5-7 minutes, 0.5-9 minutes, 0.5-10 minutes, and 0.5-12 minutes, respectively. In Figure 5, the pre-press layers (13) and post-press layers (10) are depicted. In this figure, adhesive molecules (15) can be observed between the pre-press layers (13). After pressing, the layers (10) exhibit a structure where the adhesive molecules (15) have penetrated into the layers (10).

[0063] With this method, it is not possible to produce blocks (11) with a thickness exceeding 5 mm. When blocks (11) thicker than 5 mm are desired, the adhesive dries prematurely during the application stage due to the large number of layers (10). This prevents the adhesive from being evenly distributed among the layers (10), effectively penetrating the layers (10), and facilitating the effective evacuation of air between the layers (10) during the pressing stage (30).

[0064] For this reason, the blocks (11) produced at the end of the pressing stage (30) are used as building units for the production of the sheet (12), as shown in Figure 3. To this end, adhesive, preferably dextrin, is applied in sufficient quantity to at least one block surface (111) of multiple blocks (11) at a surface density of 40-60 g / m2to form a sheet (12). The sheet (12) is ensured to have a thickness of at least 5 mm. Preferably, adhesive is applied to at least one bare surface (101) of the layers (10) at the edges of each block (11). Then, the blocks (11) are stacked on top of each other, with the adhesive-coated surface (101) of one block (11) coming into contact with one of the surfaces (101) of the edge layers (10) from another block (11), or in other words, one of the block surfaces (111).

[0065] The stacked blocks (11) are then subjected to a second pressing stage (40). In the second press (40), a pressure ranging from 50 to 150 bars, preferably between 59 and 79 bars, is applied. The second pressing stage (40) is carried out for 0.5 to 10 hours, depending on the thickness of the stacked blocks (11).

[0066] During the second pressing stage (40), the ambient temperature may vary between 20°C and 28°C. However, to reduce the process duration, the conditioned ambient temperature in the second pressing stage (40) is preferably maintained around 90°C to 110°C.

[0067] During the second pressing stage (40), the adhesive in the stacked blocks (11) is dried. As a result, uniform distribution of the adhesive is achieved, and a sheet (12) with smoothed surfaces is produced. In some applications of the invention, the blocks (11) exiting the second pressing stage (40) are left to rest further without applying any additional pressure or heat.

[0068] After the second pressing stage (40), the stacked blocks (11) are preferably sent to the sizing (50) and shaping section to achieve sheets (12) in the desired geometry and dimensions. In the sizing (50) section, large saws, router blades, Computer Numerical Control (CNC) routers, plotters, laser cutters, or punch cutters can be used. During this stage, shaping the sheet (12) allows the production of geometries such as cylinders, pyramids, cubes, blocks, wedges, or slats.

[0069] The mentioned sizing techniques prevent the separation of layers (10) from one another. This method also provides an additional advantage. Normally, paper bonded with adhesive tends to separate when shaped into cylindrical forms. However, sheets (12) produced with this method eliminate this issue. During or after the production or bending stages, no separation occurs between the layers (10).

[0070] In some applications of the invention, borax is added to the adhesive in a weight ratio of 5-20%, preferably 7-12%, before it is applied to the layer surface (101). Borax acts as an agent that reduces the material's contact with oxygen. Therefore, the addition of borax enhances the flameretardant properties of the sheet (12). Additionally, as borax is known for its antifungal properties, it strengthens the antifungal characteristics of the sheet (12). Due to the porous structure of the layers (10), borax penetrates into the layers (10) along with the adhesive applied between the layers (10) and blocks (11), increasing the fire resistance of the sheet.

[0071] In certain embodiments of the invention, the recycled paper / cardboard used as the layer (10) preferably has a moisture content of at least 5%, ideally between 5% and 15% by weight. If the moisture content is below 5%, the adhesive will primarily try to saturate the layer (10), resulting in suboptimal adhesion performance. There is a positive correlation between the moisture content in the layer (10) and adhesive absorption. When needed, water or steam is sprayed onto the layer (10) before the lamination stage to increase the solution penetration rate. As a result, production speed and absorption improve.

[0072] In some applications of the invention, the sheets (12) obtained at the end of the sizing (50) section can be subjected to optional processes (60) to impart properties such as water repellency and anti-static behavior. These applications can be implemented on the final sheets (12) through spraying or dipping methods.

[0073] The sheet (12) obtained by the described method has flame-retardant properties and enhanced mechanical characteristics, including resistance to cracking, increased fracture strength, improved screw-holding capacity, enhanced sound insulation, and better thermal insulation.

[0074] A sample sheet (12) with dimensions of 990 mm in length, 193.3 mm in width, and 19.6 mm in thickness was subjected to a destructive impact test to determine its fracture strength. For this test, the specified sheet (12) sample was placed on a support with a span of 660 mm. The test was performed on four different sheet (12) samples, and the sample sheet (12) exhibited an average fracture strength of 14.8 MPa and a fracture load of 1.1 kN. Table 1 presents the results of the destructive impact test.

[0075] Table 1. Destructive Impact Test Results

[0076] A sheet with a thickness of 4 cm was subjected to a thermal conductivity test at an ambient temperature of 23 °C. One surface of the sheet was heated, and the temperature of the heated surface reached 150 °C. However, due to the improved thermal insulation properties of the sheet, the temperature on the opposite surface rose to only 26 °C during 32 seconds of heat exposure.

[0077] In another test, the 4 cm-thick sheet was exposed to flame for 3 minutes. At the end of the 3- minute exposure, the temperature of the flame-applied surface reached at least 576 °C. However, in the same test, the temperature on the opposite surface, where no flame was applied, varied between 47 °C and 32 °C. It is also predicted that the sheet would demonstrate high performance in a 26-minute version of the same test, which is another recognized standard.

[0078] To determine the toxicity of the sheet, three samples were conditioned at a temperature of 23±2 °C and a relative humidity of 50±5%. These samples were 22.5 mm thick, with surface dimensions of 65 mm by 65 mm and a unit area density of 18.93 kg / m2Additionally, all surfaces of the samples, except the 65 mm by 65 mm surface exposed to heat, were covered with aluminum foil.

[0079] Non-flame pilot and 25 kWm2heat flux tests were conducted on these samples. The optical density of the resulting smoke was measured according to TS EN ISO 5659-2:2018 (Determination of Optical Density by Single Chamber Test). The concentrations of toxic gases in the smoke were measured according to TS EN 17084:2019 (Railway Applications - Fire Protection of Railway Vehicles - Toxicity Test for Materials and Components). Heat flux application lasted for 600 seconds.

[0080] In the resulting gas, almost no hydrogen cyanide (HCN) or hydrogen bromide (HBr) was detected, and no hydrogen fluoride (HF) was observed at any point. The results of the toxic gas concentrations for the three different samples are presented in Table 2, Table 3, and Table 4.

[0081] When comparing the concentrations of carbon dioxide (CCE), carbon monoxide (CO), hydrochloric acid (HC1), hydrogen fluoride (HF), hydrogen bromide (HBr), nitric oxide (NO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) with the safety limits defined by the Occupational Safety and Health Administration (OSHA), it is observed that the safety thresholds are 5000 ppm (9000 mg / m3) for CO2, 50 ppm (55 mg / m3) for CO, 5 ppm (7 mg / m3) for HC1, 3 ppm (2 mg / m3) for HF, 3 ppm (10 mg / m3) for HBr, 25 ppm (30 mg / m3) for NO, 5 ppm (9 mg / m3) forNO2, and 5 ppm (13 mg / m3) for SO2. The results show that the concentrations of carbon dioxide, hydrochloric acid, hydrogen bromide, hydrogen fluoride, nitric oxide, nitrogen dioxide, and sulfur dioxide gases were all within OSHA's safe limits. However, the concentration of carbon monoxide exceeded the safety limit.

[0082]

[0083] Table 2. Toxicity Test Results (1st Iteration)

[0084]

[0085] Table 2. Toxicity Test Results (2nd Iteration)

[0086] 5

[0087]

[0088] Table 3. Toxicity Test Results (3rd Iteration)

[0089] The results of the smoke optical density test are presented in Table 5. The time-dependent transmission and specific optical density for each sample can be observed in Figures 7, 8, 9, 10, 11, and 12.

[0090] Table 5. Smoke Optical Density Test Results In a sound insulation experiment conducted on the sheet (12), a sound source emitting 62 decibels in air under standard conditions was placed inside a box made from 4 cm thick sheets (12) prepared using the method described in this invention. As a result of using this box, the sound level emitted by the source was reduced to only 25 decibels. The sheet (12) produced using the described method can be used as an alternative building material for walls. Due to its shapeability and enhanced mechanical properties, it can serve as a support material such as a block or pallet in transportation. Furthermore, thanks to its advanced mechanical features, it is suitable for use as a framework, panel, or wall in the furniture and construction industries. Additionally, the sheet (12) can be cut into thin longitudinal strips for use as slats.

[0091] The surfaces of the final product, the sheet (12), are suitable for coating with materials such as plaster, decorative paper, fabric, phenolic film, or plastic laminate.

Claims

AMENDED CLAIMS received by the International Bureau on 08 December 20251. A method for producing a sheet (12) is characterized by comprising the following steps: a) Coating at least one surface (101) of multiple layers (10) made of recycled paper or cardboard with a rough and porous surface with an adhesive at a surface density of 40-60 g / m2, b) Stacking the adhesive-coated layers (10) in a lamination (20) station such that the adhesive is present between any two layers (10), c) Pressing the stacked layers (10) with a pressure ranging between 50 and 200 bars for 0.5 to 15 minutes to ensure that at least part of the adhesive penetrates the layers (10) and reduces or eliminates the roughness on the surfaces of the layers (10), thereby forming a block (11), d) Coating at least two blocks (11) on at least one block surface (111) with an adhesive at a surface density of 40-60 g / m2and stacking the blocks (11) such that adhesive is present between any two blocks (11) and are subjected to processing in a second pressing stage (40) under a pressure ranging between 50 and 150 bars for 0.5 to 10 hours to produce a sheet (12) with a thickness of at least 5 mm.

2. A production method according to Claim 1, characterized by using recycled paper / cardboard with a moisture content of at least 5% as the recycled paper / cardboard.

3. A production method according to Claim 1 or 2, characterized by coating layers (10) made of recycled paper / cardboard with a Bendtsen air permeability of at least 500 mL / min with adhesive.

4. A production method according to any of Claims 1-3, characterized by coating layers (10) made of recycled paper / cardboard with a roughness of at least 3 pm with adhesive.

5. A production method according to any of the preceding claims, characterized by using a polyvinyl alcohol-based adhesive as the adhesive.

6. A production method according to any of Claims 1-4, characterized by using a starch- based adhesive as the adhesive.

7. A production method according to Claim 6, characterized by using dextrin as the starch- based adhesive.

8. A production method according to any of the preceding claims, characterized by adding borax to the adhesive in an amount of 5-20% by weight of the adhesive.

9. A production method according to any of the preceding claims, characterized by adding borax to the adhesive in an amount of 7-12% by weight of the adhesive.

10. A production method according to any of the preceding claims, characterized by stacking 2-5 layers (10) on top of each other in the lamination (20) station.

11. A production method according to any of the preceding claims, characterized by pressing of step b at a temperature of 17-26 °C.

12. A production method according to any of Claims 1-10, characterized by shortening the pressing time in the pressing of step b by using a heated conveyor, which applying pressure from above, operating at 70-120 °C.

13. A production method according to any of the preceding claims, characterized by applying pressure in the pressing of step b using either a press machine or by placing a specific weight on the stacked layers (10).

14. A production method according to any of the preceding claims, characterized by applying a pressure of 50-59 bars for 0.5-7 minutes in the pressing of step b for the production of a sheet (12) with a thickness of 5-20 mm.

15. A production method according to any of Claims 1-13, characterized by applying a pressure of 59-79 bars for 0.5-9 minutes in pressing of step b for the production of a sheet (12) with a thickness of 21-30 mm16. A production method according to any of Claims 1-13, characterized by applying a pressure of 79-98 bars for 0.5-10 minutes in the pressing of step b for the production of a sheet (12) with a thickness of 31-50 mm.

17. A production method according to any of Claims 1-13, characterized by applying a pressure of 98-138 bars for 0.5-12 minutes in pressing of step b for the production of a sheet (12) with a thickness greater than 51 mm.

18. A production method according to any of the preceding claims, characterized by applying pressure in the second pressing stage (40) at an ambient temperature of 20-28 °C.

19. A production method according to any of the preceding claims, characterized by reducing the processing time in the second pressing stage (40) by setting the ambient temperature to 90-110 °C.

20. A production method according to Claim 20, characterized by further comprises a step of sizing by using large saws, router blades, Computer Numerical Control (CNC) routers, plotters, laser cutters, or punch cutters.

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