A method for preparing a dry paper-based cushioning material and the dry paper-based cushioning material.

Abstract

This invention relates to the field of paper-based materials technology, and discloses a method for preparing a dry-process paper-based cushioning material and the dry-process paper-based cushioning material itself. This invention uses flexible polyurethane foam as a binder, leveraging its foaming ability to increase cushioning performance and also acting as a binder for fibers. Additionally, hot-melt fibers also play a bonding role and enhance the material's strength. Cellulose nanofibers ensure the high strength of the polyurethane material, giving each layer similar strength, thereby ensuring the overall strength of the material. The paper-based cushioning material prepared using this method has significant advantages in strength and cushioning performance, protecting items from external impacts. This invention employs a dry molding process, which, compared to traditional wet methods, reduces water consumption and wastewater discharge; using only a small amount of adhesive effectively reduces environmental pressure and promotes the development of more environmentally friendly and efficient packaging solutions.

Description

Technical Field

[0001] This invention relates to a method for preparing a dry paper-based cushioning material and the dry paper-based cushioning material itself, belonging to the field of paper-based material technology. Background Technology

[0002] In the modern packaging industry, cushioning materials play a crucial role, especially in protecting fragile items from impacts, vibrations, and pressure damage during transportation and handling. Paper-based cushioning materials, as an environmentally friendly and highly efficient new type of cushioning material, have received widespread attention and development in recent years. Traditional cushioning materials such as polyethylene foam (EPE) and polystyrene foam (EPS), while possessing good cushioning performance, suffer from drawbacks such as difficulty in degradation and recycling, placing a certain burden on the environment. In contrast, paper-based cushioning materials use renewable resources as raw materials, effectively reducing environmental pollution and aligning with the development concept of a circular economy.

[0003] Dry forming technology is a forming process relative to the traditional wet process. It uses air instead of water as the medium for dispersing and transporting fibers, primarily through physical methods (using only a small amount of adhesive) to process paper fibers or other fibrous materials into cushioning products with specific shapes and structures. This manufacturing process does not require large amounts of water, reducing water consumption and wastewater discharge, thus lowering environmental impact. It also reduces the enormous energy consumption required for the drying process in traditional wet manufacturing, saving significant energy. Furthermore, due to the good air permeability of paper-based materials, dry-process paper-based cushioning materials exhibit unique advantages in applications requiring maintained humidity or ventilation. With increasing societal awareness of environmental protection and technological advancements, dry-process paper-based cushioning materials, with their green and sustainable characteristics, are gradually becoming an important development direction in the future packaging industry. Summary of the Invention

[0004] The technical problem this invention aims to solve is to address the high energy consumption of wet molding processes by utilizing dry molding technology to prepare a paper-based cushioning material with excellent elasticity and strength. This technology features low energy consumption, simple steps, and ease of operation. This invention also provides a method for preparing a dry-process paper-based cushioning material. This method utilizes flexible polyurethane foam, cellulose nanofibers, and hot-melt fibers to prepare a paper-based material with excellent strength and cushioning effect, while ensuring ease of operation and controllability to meet the needs of different application scenarios.

[0005] To solve the above problems, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a dry paper-based cushioning material, comprising the following steps:

[0007] Step 1) Take the pulp board, divide it into small pieces, put it into a shredder to break it into pulp fibers, and filter out the fine fiber particles;

[0008] Step 2) Mix the above pulp fibers with hot melt fibers to obtain mixed fibers;

[0009] Step 3) Prepare polyurethane foam material by uniformly spraying a layer of polyurethane foam material onto the bottom of the mold;

[0010] Step 4) Quickly spread the mixed fibers from step 2) evenly on the surface of the polyurethane foam material to obtain a mixed fiber layer;

[0011] Step 5) Quickly spray a layer of polyurethane foam material onto the surface of the mixed fiber layer, and press it firmly with a cover plate to ensure it is fully bonded;

[0012] Step 6) Repeat the above steps until the total material thickness reaches the target requirement;

[0013] Step 7) Place the prepared mold material in an oven for heating treatment. On the one hand, the polyurethane foam material foams and matures, thereby playing an adhesive and buffering role; on the other hand, the hot melt fiber partially melts, thereby playing a further adhesive role. Then, cool to obtain the final product.

[0014] Preferably, in step 1), the pulp board includes one or both of softwood pulp board and hardwood pulp board. When both are used, the weight ratio of the softwood pulp board to the hardwood pulp board is 3:7 to 5:5.

[0015] Preferably, in step 1), the pulp board is different from the solid pulp board and is obtained by dispersing the solid pulp board.

[0016] Preferably, in step 1), the time for the pulverizer to mechanically crush the pulping plate is controlled between 8 and 30 seconds.

[0017] Preferably, in step 2), the mixing ratio of hot melt fiber to pulp fiber is 1:9 to 2:8, and the hot melt fiber includes one of PE fiber and ES fiber.

[0018] Preferably, in step 3), the method for preparing the special soft polyurethane foam material includes: sequentially and precisely adding polyether polyol 2070A, polyether polyol EP-330N, polymer polyol POP3682, foam stabilizer B8002, triethylenediamine, dibutyltin dilaurate, and deionized water to an aerosol can according to the specified ratio; then adding weighed diphenylmethane diisocyanate W8019 raw material and cellulose nanofibers; then filling with gas, sealing the can opening, shaking the can thoroughly, and connecting it to a spray gun head for use.

[0019] Preferably, in step 3), cellulose nanofibers are added to the special soft polyurethane foam material to enhance the strength of the polyurethane foam layer material. By adjusting the size and addition ratio of the cellulose nanofibers, the mechanical properties are similar to those of the upper and lower fiber layers.

[0020] More preferably, the cellulose nanofibers should have a diameter ≤100nm, a length between 0.5 and 20μm, and the ratio of cellulose nanofibers to polyurethane foam material should be between 0.5:9.5 and 3:7.

[0021] Preferably, in step 4), the ratio of polyurethane foam material to mixed fiber is controlled between 1.2:8.8 and 1.6:8.4.

[0022] Preferably, in step 4), the thickness of each fiber layer is controlled to be around 5 to 8 mm.

[0023] Preferably, in step 7), the oven temperature is controlled between 135 and 140°C, and the time is controlled between 20 and 45 minutes.

[0024] Secondly, the present invention also provides a paper-based cushioning material prepared by the above-described preparation method.

[0025] Preferably, the paper-based cushioning material comprises 7-8 parts by weight of pulp fiber, 0.8-1.8 parts by weight of hot melt fiber, and 1.2-1.6 parts by weight of polyurethane foam material.

[0026] Preferably, the pulp fiber is a mixture of softwood pulp and hardwood pulp, with a weight ratio of 3:7 to 5:5.

[0027] Preferably, the hot-melt fiber includes PE fiber and ES fiber.

[0028] This invention provides a paper-based cushioning material and its preparation method. The preparation steps of this paper-based cushioning material are simple and easy to operate. The dry-process paper-based cushioning material provided by this invention can provide excellent compression and shock absorption performance, protecting items from external impacts. It is recyclable and biodegradable, which is in line with the development trend of modern green packaging. This invention uses a dry forming process to prepare the paper-based cushioning material. Compared with the traditional wet process, its production process does not use water, reducing water consumption and wastewater discharge. It uses only a small amount of adhesive, effectively reducing environmental pressure and promoting the development of more environmentally friendly and efficient packaging solutions. Attached Figure Description

[0029] Figure 1 A flowchart illustrating the method for preparing paper-based cushioning material provided by the present invention. Detailed Implementation

[0030] To make the present invention more apparent and understandable, preferred embodiments are described in detail below.

[0031] Preparation Example

[0032] A special flexible polyurethane foam material comprises the following components by weight:

[0033] 40 parts of polyether polyol 2070A (Dow Chemical Company);

[0034] 50 parts of polyether polyol EP-330N (Shandong Lanxing Dongda Chemical Co., Ltd.);

[0035] 10 portions of polymer polyol POP3682 (Shandong Lanxing Dongda Chemical Co., Ltd.);

[0036] One part of foam stabilizer B8002 (Evonik Degussa (China) Investment Co., Ltd.);

[0037] Triethylenediamine (Shandong Binli New Materials Co., Ltd.) 0.3 parts;

[0038] Dibutyltin dilaurate (Air Products, Inc.) 0.1 part;

[0039] 3 parts deionized water;

[0040] 70 parts of diphenylmethane diisocyanate W8019 (Wanhua Chemical Group Co., Ltd.);

[0041] 10 parts of cellulose nanofibers (diameter ≤100nm, length between 0.5 and 20μm).

[0042] The preparation method is as follows: In an aerosol can, polyether polyol 2070A, polyether polyol EP-330N, polymer polyol POP3682, foam stabilizer B8002, triethylenediamine, dibutyltin dilaurate and deionized water are added in sequence according to the specified ratio. Then, weighed diphenylmethane diisocyanate W8019 raw material and cellulose nanofibers are added. Then, gas (DME and propane) is filled in, the can is sealed, the can is shaken thoroughly, and then it is connected to the spray gun head for use.

[0043] Example 1

[0044] A paper-based cushioning material comprises the following components by weight: 7.92 parts pulp fiber, 0.88 parts hot melt fiber, and 1.2 parts polyurethane foam material.

[0045] The method for preparing the paper-based cushioning material includes the following steps:

[0046] (1) Prepare two types of pulp boards, softwood pulp board and hardwood pulp board, divide them into small pieces of 0.5cm×0.5cm and put them into a shredder. Control the shredder to shred for 11s to break them into pulp fibers. Filter out the fine fiber particles. Repeat this step to obtain sufficient pulp fibers. Then mix the two types of pulp fibers evenly in a ratio of 4:6.

[0047] (2) Take 7.92 parts of the above-mentioned uniformly mixed pulp fiber and 0.88 parts of PE fiber, mix them evenly to obtain mixed fiber;

[0048] (3) The total weight of polyurethane foam material used in this preparation (according to the preparation method described in the preparation example) is 1.2 parts. Use a spray gun to evenly spray a layer of the prepared special soft polyurethane foam material on the bottom of the mold. Note the amount of polyurethane foam material used each time.

[0049] (4) Quickly and evenly spread the mixed fibers on the surface of the polyurethane foam material to obtain a mixed fiber layer, and control the thickness of the mixed fiber layer to be about 6 mm.

[0050] (5) Quickly spray a layer of polyurethane foam material onto the surface of the mixed fiber layer. At this time, it is also important to control the amount of polyurethane foam material used. Then use a cover plate to press it down appropriately so that it is fully bonded.

[0051] (6) Repeat the above steps until the total material thickness meets the target requirements;

[0052] (7) The mold material is placed in an oven for heating treatment. The oven temperature is set to 140℃ and the heating time is 35min. Heating makes the polyurethane foam material foam and mature, which plays a bonding and buffering role. On the other hand, it melts the PE fiber and plays a bonding role. The melted PE fiber makes the internal bonding of the pulp fiber more complete. After cooling, the final product is obtained.

[0053] Example 2

[0054] A paper-based cushioning material comprises the following components by weight: 7.04 parts pulp fiber, 1.76 parts hot melt fiber, and 1.2 parts polyurethane foam material.

[0055] The method for preparing the paper-based cushioning material includes the following steps:

[0056] (1) Prepare two types of pulp boards, softwood pulp board and hardwood pulp board, divide them into small pieces of 0.5cm×0.5cm and put them into a shredder. Control the shredder to shred for 11s to break them into pulp fibers. Filter out the fine fiber particles. Repeat this step to obtain sufficient pulp fibers. Then mix the two types of pulp fibers evenly in a ratio of 4:6.

[0057] (2) Take 7.04 parts of the above-mentioned uniformly mixed pulp fiber and 1.76 parts of PE fiber, mix them evenly to obtain mixed fiber;

[0058] (3) The total weight of polyurethane foam material used in this preparation (according to the preparation method described in the preparation example) is 1.2 parts. Use a spray gun to evenly spray a layer of the prepared special soft polyurethane foam material on the bottom of the mold. Note the amount of polyurethane foam material used each time.

[0059] (4) Quickly and evenly spread the mixed fibers on the surface of the polyurethane foam material to obtain a mixed fiber layer, and control the thickness of the mixed fiber layer to be about 7mm.

[0060] (5) Quickly spray a layer of polyurethane foam material onto the surface of the mixed fiber layer. At this time, it is also important to control the amount of polyurethane foam material used. Then use a cover plate to press it down appropriately so that it is fully bonded.

[0061] (6) Repeat the above steps until the total material thickness meets the target requirements;

[0062] (7) The mold material is placed in an oven for heating treatment. The oven temperature is set to 140℃ and the heating time is 40min. Heating makes the polyurethane foam material foam and mature, which plays a bonding and buffering role. On the other hand, it melts the PE fiber and plays a bonding role. The melted PE fiber makes the internal bonding of the pulp fiber more complete. After cooling, the final product is obtained.

[0063] Example 3

[0064] A paper-based cushioning material comprises the following components by weight: 7.56 parts pulp fiber, 0.84 parts hot melt fiber, and 1.6 parts polyurethane foam material.

[0065] The method for preparing the paper-based cushioning material includes the following steps:

[0066] (1) Prepare two types of pulp boards, softwood pulp board and hardwood pulp board, divide them into small pieces of 0.5cm×0.5cm and put them into a shredder. Control the shredder to shred for 11s to break them into pulp fibers. Filter out the fine fiber particles. Repeat this step to obtain sufficient pulp fibers. Then mix the two types of pulp fibers evenly in a ratio of 4:6.

[0067] (2) Take 7.56 parts of the above-mentioned uniformly mixed pulp fiber and 0.84 parts of ES fiber, mix them evenly to obtain mixed fiber;

[0068] (3) The total weight of polyurethane foam material used in this preparation (according to the preparation method described in the preparation example) is 1.6 parts. Use a spray gun to evenly spray a layer of the prepared special soft polyurethane foam material on the bottom of the mold. Note the amount of polyurethane foam material used each time.

[0069] (4) Quickly and evenly spread the mixed fibers on the surface of the polyurethane foam material to obtain a mixed fiber layer, and control the thickness of the mixed fiber layer to be about 7mm.

[0070] (5) Quickly spray a layer of polyurethane foam material onto the surface of the mixed fiber layer. At this time, it is also important to control the amount of polyurethane foam material used. Then use a cover plate to press it down appropriately so that it is fully bonded.

[0071] (6) Repeat the above steps until the total material thickness meets the target requirements;

[0072] (7) The mold material is placed in an oven for heating treatment. The oven temperature is set to 135℃ and the heating time is 40min. Heating makes the polyurethane foam material foam and mature, which plays a bonding and buffering role. On the other hand, it melts the ES fiber and plays a bonding role. The melted ES fiber makes the internal bonding of the pulp fiber more complete. After cooling, the final product is obtained.

[0073] Comparative Example

[0074] A method for preparing a cushioning packaging material includes the following steps:

[0075] (1) Weigh out 65 parts corn starch, 55 parts rice straw (80 mesh), 10 parts kaolin, and 1.5 parts glyceryl monostearate by weight and mix them evenly to obtain a mixture.

[0076] (2) Add the mixture obtained in step (1) along with 10 parts of polyvinyl alcohol and 1.5 parts of sodium hydroxide to 180 parts of water, stir evenly, add 4 parts of aluminum powder foaming agent, stir evenly and pour into the mold, put the mold into the oven, dry at 135℃ for 1.5h, cool, demold, and obtain the finished product.

[0077] The performance of the paper-based cushioning materials in Examples 1-3 and the cushioning packaging materials in the comparative examples was tested, and the results are shown in Table 1 below.

[0078] (1) Compression rebound rate: The percentage of the sample volume to the original volume after the volume of the obtained cushioning packaging material is compressed by 50% and maintained for 72 hours.

[0079] (2) Impact strength: The impact strength is tested in accordance with GB / T 17657-2022.

[0080] Table 1

[0081] name Rebound rate (%) <![CDATA[Impact strength (KJ·m 2 )]]> <![CDATA[Density (kg / m 3 )]]> Example 1 83 6.81 52 Example 2 87 6.93 55 Example 3 84 7.05 59 Comparative Example 82.1 6.58 152

[0082] As can be seen from the table, the three types of paper-based cushioning materials prepared have good resilience and impact resistance. Their resilience and impact strength are superior to those of the material prepared in the comparative example, and their density is also significantly better than that of the comparative example, making them suitable for use in the packaging material field. In addition, the oven heating time required in the preparation process of this method is much shorter than that of the comparative example, greatly reducing energy consumption and balancing production costs to a certain extent.

[0083] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a dry-process paper-based cushioning material, characterized in that, Includes the following steps: Step 1) Take the pulp board, divide it into small pieces, put it into a shredder to break it down into pulp fibers, and filter out the fine fiber particles; Step 2) Mix the above pulp fibers with hot melt fibers to obtain mixed fibers; Step 3) Prepare polyurethane foam material by uniformly spraying a layer of polyurethane foam material onto the bottom of the mold; Step 4) Quickly spread the mixed fibers from step 2) evenly on the surface of the polyurethane foam material to obtain a mixed fiber layer; Step 5) Quickly spray a layer of polyurethane foam material onto the surface of the mixed fiber layer, and press it down with a cover plate to ensure it is fully bonded; Step 6) Repeat the above steps until the total material thickness reaches the target requirement; Step 7) Place the prepared mold material in an oven for heating treatment. On the one hand, the polyurethane foam material foams and matures, thereby playing an adhesive and cushioning role; on the other hand, the hot melt fiber partially melts, thereby playing a further adhesive role. Then, cool to obtain the final product. In step 2), the mixing ratio of hot melt fiber to pulp fiber is 1:9 to 2:8, and the hot melt fiber includes one of PE fiber and ES fiber. In step 3), the polyurethane foam material preparation method includes: adding polyether polyol 2070A, polyether polyol EP-330N, polymer polyol POP3682, foam stabilizer B8002, triethylenediamine, dibutyltin dilaurate and deionized water to an aerosol can in sequence according to the specified ratio; then adding weighed diphenylmethane diisocyanate W8019 raw material and cellulose nanofibers; then filling with gas, sealing the can opening, shaking the can thoroughly, and connecting to a spray gun head for use. In step 4), the ratio of polyurethane foam material to mixed fiber is controlled between 1.2:8.8 and 1.6:8.

4. In step 4), the thickness of each fiber layer is controlled at 5-8 mm.

2. The preparation method according to claim 1, characterized in that, In step 1), the pulp board includes one or both of softwood pulp board and hardwood pulp board. When both are used, the weight ratio of softwood pulp board to hardwood pulp board is 3:7 to 5:

5.

3. The preparation method according to claim 1, characterized in that, In step 1), the time for the pulverizer to mechanically crush the pulping plate is controlled between 8 and 30 seconds.

4. The preparation method according to claim 1, characterized in that, In step 3), the cellulose nanofibers should preferably have a diameter ≤100nm, a length between 0.5 and 20μm, and the ratio of cellulose nanofibers to polyurethane foam material should be between 0.5:9.5 and 3:

7.

5. The preparation method according to claim 1, characterized in that, In step 7), the oven temperature is controlled between 135 and 140°C, and the time is controlled between 20 and 45 minutes.

6. A dry-process paper-based cushioning material, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

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