Corrugated carton with heat insulation and heat preservation functions

Abstract

The invention discloses a corrugated carton with heat insulation and heat preservation functions, and belongs to the field of carton materials. The corrugated carton comprises surface paper, a corrugated paper core, a heat insulation layer and inner paper which are sequentially stacked, the heat insulation layer is made of cellulose-polyurethane composite aerogel, and the corrugated carton is prepared through the following steps that glycerin is added into cellulose pretreatment liquid containing a cellulose source, ultrasonic treatment is conducted, and cellulose suspension liquid is obtained; the preparation method comprises the following steps: mixing cellulose suspension with polyurethane, then adding a cross-linking agent, reacting to obtain cellulose-polyurethane composite sol, then immersing the cellulose-polyurethane composite sol into a hydrophobic modifier, then transferring the cellulose-polyurethane composite sol into a freeze dryer, drying the cellulose-polyurethane composite sol at the temperature of-50 to-30 DEG C under the pressure of 0.1-0.4 mbar to obtain porous composite aerogel, and finally, carrying out hot pressing and spraying a polylactic acid solution to obtain the composite aerogel. The cellulose-polyurethane composite aerogel is obtained. The cellulose-polyurethane composite aerogel is used as a heat insulation layer of the corrugated carton, so that the heat insulation performance of the corrugated carton can be improved, and the structural stability of the material is enhanced.

Description

Technical Field

[0001] The present invention belongs to the field of carton materials, and particularly relates to a corrugated carton with heat insulation and heat preservation functions. Background Art

[0002] With the rapid development of the fresh food e-commerce, cold chain logistics, and pharmaceutical distribution industries, the demand for transportation packaging with heat insulation performance is increasing day by day. The common heat preservation packaging on the market mainly relies on foam plastic boxes. Although it has good heat insulation effect, it has problems such as non-degradability, difficult recycling, and environmental pollution, which do not conform to the green packaging policies implemented globally.

[0003] Traditional corrugated cartons are widely used because of their advantages such as light weight, low cost, and recyclability. However, their heat insulation performance is poor and it is difficult to meet the storage and transportation requirements of temperature-sensitive goods. Therefore, it is urgent to develop a corrugated carton with excellent heat insulation and heat preservation performance, which can not only maintain the light weight and recyclability of traditional cartons, but also improve the heat insulation performance through optimizing the material combination and structural design, while taking into account environmental protection and economy to meet the high standards of cold chain logistics, pharmaceutical transportation and other fields. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a corrugated carton with heat insulation and heat preservation functions, which can increase the heat insulation and heat preservation performance of the carton while maintaining the light weight of the traditional corrugated carton, and meet the needs of cold chain and high-temperature logistics.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A corrugated carton with heat insulation and heat preservation functions, the corrugated carton includes a face paper, a corrugated paper core, a heat insulation layer, and a lining paper stacked in sequence; wherein, the material of the heat insulation layer is cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps:

[0007] S1: Provide a cellulose pretreatment solution containing a cellulose source;

[0008] S2: Add glycerol to the cellulose pretreatment solution and perform ultrasonic treatment to obtain a cellulose suspension;

[0009] S3: Mix the cellulose suspension with polyurethane, and then add a cross-linking agent to react to obtain a cellulose-polyurethane composite sol, and the polyurethane is amino-terminated polyurethane or hydroxyl-terminated polyurethane;

[0010] S4: Immerse the cellulose-polyurethane composite sol in a hydrophobic modifier;

[0011] S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at a temperature of -50 to -30 °C and a pressure of 0.1 - 0.4 mbar to obtain a porous composite aerogel;

[0012] S6: Hot press the porous composite aerogel and spray a polylactic acid solution to obtain a cellulose-polyurethane composite aerogel.

[0013] It should be noted that in the present invention, a cellulose-polyurethane composite aerogel is used as the thermal insulation layer. Among them, cellulose serves as the skeletal material, which can provide a porous structure; the flexible segments of polyurethane are embedded in the rigid network of cellulose, absorbing stress and preventing the aerogel from brittle cracking, which can enhance toughness and improve the brittleness of the aerogel. Cellulose is rich in hydroxyl groups, which can provide active sites for cross-linking reactions; the terminal functional groups in amino-terminated ATPU / hydroxyl-terminated polyurethane HTPU are -NH2 / -OH, which can also form Schiff bases or ether bonds with cross-linking agents. Therefore, the cross-linking agent can simultaneously bridge cellulose and polyurethane to form a three-dimensional interpenetrating network through the synergistic reaction of covalent bonds / hydrogen bonds, constructing a cellulose-polyurethane composite aerogel with a rigid-flexible network. The cellulose suspension and polyurethane are mixed in a mass ratio of 5 - 7:3, and the elongation at break of the composite aerogel can reach 15%, which can effectively improve the stability of the composite aerogel and further improve the thermal insulation performance of the composite aerogel.

[0014] It should also be noted that drying at -50 °C and 0.1 - 0.4 mbar in a freeze dryer can form continuous porous channels. The low temperature of -50 °C ensures that water is completely frozen into fine ice crystals, and the extremely low pressure of 0.1 - 0.4 mbar can directly sublimate the ice crystals (avoiding the presence of liquid phase), quickly remove water, reduce the capillary force during the drying process, prevent the collapse of the pore walls, and the uniform pores can effectively block heat conduction and reflect more infrared radiation, thereby obtaining more excellent thermal insulation and heat preservation performance.

[0015] In some embodiments, the cellulose source is selected from at least one of rice husk pulp, wood pulp, and cotton pulp.

[0016] In some embodiments, the temperature of the treatment liquid in S1 is 60 - 80 °C, and the reaction time is 2 - 3 h; the glycerol concentration in S2 is 0.4 - 0.7 wt%, the ultrasonic treatment time is 20 - 40 min, and the ultrasonic frequency is 30 - 50 kHz.

[0017] In some embodiments, the treatment liquid is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, and sodium bicarbonate solution.

[0018] In some embodiments, after adding a crosslinking agent in S3, the reaction is carried out at 50 - 70 °C for 40 - 60 min, the concentration of the crosslinking agent is 0.1 - 0.3 wt%, and the crosslinking agent is glutaraldehyde or glyoxal; in S4, after immersion in a hydrophobic modifier, it is allowed to stand for 22 - 26 h.

[0019] In some embodiments, the hydrophobic modifier is selected from at least one of methyltrimethoxysilane, octyltriethoxysilane, cetyltrimethoxysilane, aminopropyltriethoxysilane, trichloromethylsilane, and methyldiethoxyhydrosilane.

[0020] It should be noted that the hydrophobic agent can reduce the hygroscopicity of the aerogel, thereby improving the heat insulation performance of the composite aerogel.

[0021] In some embodiments, the drying time in S5 is 36 - 48 h; in S6, the hot pressing temperature is 60 - 80 °C, the hot pressing pressure is 0.5 - 0.7 MPa, the hot pressing time is 8 - 12 min, and the concentration of the polylactic acid solution is 4 - 6 wt%.

[0022] It should be noted that the hot pressing treatment can improve the density uniformity of the porous composite aerogel, and the polylactic acid solution can enhance the adhesion and waterproof ability of the aerogel.

[0023] In some embodiments, the thickness of the cellulose - polyurethane composite aerogel is 2 - 3 mm.

[0024] In some embodiments, the spraying thickness in S6 is 3 - 5 μm.

[0025] In some embodiments, in S3, the mass ratio of the cellulose suspension to polyurethane is 5 - 7:3.

[0026] The number of heat insulation layers in the corrugated cardboard box can be set to one or more according to actual application requirements, and can be located on any one or both sides of the corrugated paper core.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The cellulose-polyurethane composite aerogel provided by the present invention is a lightweight material with a nano-porous structure, having a high porosity and excellent thermal stability. The cellulose-based composite aerogel not only inherits the excellent heat insulation performance of the aerogel but also obtains better mechanical properties and processing properties, which can enhance the structural stability of the material and adjust its thermal properties. The nano-porous and low-density properties of the cellulose-based composite aerogel can effectively hinder the transfer of heat; it has an extremely high specific surface area and a unique pore structure with uniform pore distribution, which enables the aerogel to provide more adsorption sites and enhance the heat isolation effect. In addition to the above, a polylactic acid solution is sprayed on both sides of the cellulose-polyurethane composite aerogel provided by the present invention, further enhancing the waterproof and heat insulation properties of the composite aerogel.

[0029] 2. The present invention uses the cellulose-polyurethane composite aerogel as the heat insulation layer of the corrugated cardboard box, which can greatly improve the heat insulation and heat preservation performance of the corrugated cardboard box. In addition, after the composite aerogel is added to the corrugated cardboard box, it will not significantly increase the weight of the box, which is very beneficial for the transportation and use of the cardboard box and will not increase the transportation cost or bring inconvenience to the user due to excessive weight.

[0030] 3. The corrugated cardboard box with heat insulation and heat preservation functions provided by the present invention also has compatibility and degradability, and can play an important role in environmental protection and sustainable development. Detailed Embodiments

[0031] The present invention will be further described in detail below with reference to the embodiments.

[0032] Embodiment 1

[0033] A corrugated cardboard box with heat insulation and heat preservation functions, the corrugated cardboard box includes a face paper, a corrugated paper core, a heat insulation layer, and a lining paper stacked in sequence;

[0034] The material of the heat insulation layer is cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps:

[0035] S1: Put rice husk pulp into a sodium hydroxide solution at 70°C and react for 2 h to obtain a cellulose pretreatment solution;

[0036] S2: Add glycerol with a concentration of 0.5 wt% to the cellulose pretreatment solution and ultrasonically treat it at 40 kHz for 30 min to obtain a cellulose suspension;

[0037] S3: Mix the cellulose suspension and amino-terminated polyurethane ATPU in a mass ratio of 6:3, then add glutaraldehyde and react at 60°C for 50 min to obtain a cellulose-polyurethane composite sol;

[0038] S4: Immerse the cellulose-polyurethane composite sol in methyltrimethoxysilane and let it stand for reaction for 24 h;

[0039] S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at -50 °C and 0.1 - 0.4 mbar for 36 h to obtain a porous composite aerogel;

[0040] S6: Hot press the porous composite aerogel at 70 °C and 0.6 MPa for 10 min, and spray a polylactic acid solution with a thickness of 3 μm and a concentration of 5 Wt%, thus obtaining the cellulose-polyurethane composite aerogel.

[0041] The corrugated cardboard box with heat insulation and heat preservation functions in this example is obtained by bonding the face paper, corrugated paper core, the above-prepared heat insulation layer - cellulose-polyurethane composite aerogel, and the inner paper in sequence from outside to inside with an adhesive. Among them, the adhesive can be selected from common adhesives on the market such as polyvinyl alcohol adhesive, sodium silicate adhesive, and starch-based adhesive.

[0042] Example 2

[0043] The material of the heat insulation layer in this example is cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps:

[0044] S1: Put wood pulp into a sodium hydroxide solution at 60 °C and react for 3 h to obtain a cellulose pretreatment solution;

[0045] S2: Add glycerol with a concentration of 0.4 wt% to the cellulose pretreatment solution and ultrasonically treat it at 30 kHz for 30 min to obtain a cellulose suspension;

[0046] S3: Mix the cellulose suspension and hydroxyl-terminated polyurethane HTPU in a mass ratio of 5:3, then add glyoxal and react at 50 °C for 40 min to obtain a cellulose-polyurethane composite sol;

[0047] S4: Immerse the cellulose-polyurethane composite sol in octyltriethoxysilane and let it stand for reaction for 22 h;

[0048] S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at -40 °C and 0.2 mbar for 48 h to obtain a porous composite aerogel;

[0049] S6: Hot press the porous composite aerogel at 60 °C and 0.5 MPa for 8 min, and spray a polylactic acid solution with a thickness of 4 μm and a concentration of 5 Wt%, thus obtaining the cellulose-polyurethane composite aerogel.

[0050] The preparation of the corrugated cardboard box with heat insulation and heat preservation functions in this example is the same as that in Example 1.

[0051] Example 3

[0052] In this embodiment, the material of the heat insulation layer is cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps:

[0053] S1: Put cotton pulp into a sodium hydroxide solution at 80°C and react for 3 h to obtain a cellulose pretreatment solution;

[0054] S2: Add glycerol with a concentration of 0.7 wt% to the cellulose pretreatment solution and perform ultrasonic treatment at 50 kHz for 40 min to obtain a cellulose suspension;

[0055] S3: Mix the cellulose suspension and amino-terminated polyurethane ATPU in a mass ratio of 7:3, then add glutaraldehyde and react at 70°C for 60 min to obtain a cellulose-polyurethane composite sol;

[0056] S4: Immerse the cellulose-polyurethane composite sol in cetyltrimethoxysilane and let it stand for reaction for 26 h;

[0057] S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at -30°C and 0.4 mbar for 48 h to obtain a porous composite aerogel;

[0058] S6: Hot press the porous composite aerogel at 80°C and 0.7 MPa for 12 min, and spray a polylactic acid solution with a thickness of 5 μm and a concentration of 6 Wt% to obtain the cellulose-polyurethane composite aerogel.

[0059] The preparation of the corrugated cardboard box with heat insulation and heat preservation functions in this embodiment is the same as that in Embodiment 1.

[0060] Example 4

[0061] In this embodiment, the material of the heat insulation layer is cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps:

[0062] S1: Put rice husk pulp into a sodium hydroxide solution at 70°C and react for 2.5 h to obtain a cellulose pretreatment solution;

[0063] S2: Add glycerol with a concentration of 0.6 wt% to the cellulose pretreatment solution and perform ultrasonic treatment at 35 kHz for 35 min to obtain a cellulose suspension;

[0064] S3: Mix the cellulose suspension and amino-terminated polyurethane ATPU in a mass ratio of 6:3, then add glyoxal and react at 60°C for 60 min to obtain a cellulose-polyurethane composite sol;

[0065] S4: Immerse the cellulose-polyurethane composite sol in aminopropyltriethoxysilane and let it stand for reaction for 25 h;

[0066] S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at -50 °C and 0.4 mbar for 44 h to obtain a porous composite aerogel;

[0067] S6: Hot press the porous composite aerogel at 75 °C and 0.6 MPa for 9 min, and spray a polylactic acid solution with a thickness of 3 μm and a concentration of 5 Wt%, thus obtaining a cellulose-polyurethane composite aerogel.

[0068] Example 5

[0069] The material of the thermal insulation layer in this example is a cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps:

[0070] S1: Put wood pulp into a sodium hydroxide solution at 75 °C and react for 3 h to obtain a cellulose pretreatment solution;

[0071] S2: Add glycerol with a concentration of 0.45 wt% to the cellulose pretreatment solution and perform ultrasonic treatment at 20 kHz for 35 min to obtain a cellulose suspension;

[0072] S3: Mix the cellulose suspension and amino-terminated polyurethane ATPU in a mass ratio of 5:3, then add glyoxal and react at 60 °C for 60 min to obtain a cellulose-polyurethane composite sol;

[0073] S4: Immerse the cellulose-polyurethane composite sol in aminopropyltriethoxysilane and let it stand for reaction for 26 h;

[0074] S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at -50 °C and 0.4 mbar for 46 h to obtain a porous composite aerogel;

[0075] S6: Hot press the porous composite aerogel at 75 °C and 0.7 MPa for 12 min, and spray a polylactic acid solution with a thickness of 4 μm and a concentration of 5 Wt%, thus obtaining a cellulose-polyurethane composite aerogel.

[0076] Comparative Example 1

[0077] The preparation steps of this example are the same as those of Example 1, and the only difference is that in S3, the cellulose suspension and polyurethane are mixed in a mass ratio of 4:7.

[0078] Comparative Example 2

[0079] The preparation steps of this example are the same as those of Example 1, and the only difference is that S5 adopts a normal temperature vacuum drying method.

[0080] Comparative Example 3

[0081] The preparation steps of this example are the same as those of Example 1, and the only difference is that no hydrophobic modifier is added.

[0082] Comparative Example 4

[0083] This example is the same as that of Example 1 in the preparation steps, with the only difference being that no heat insulation layer is added.

[0084] Performance tests were carried out on the corrugated cardboard boxes with heat insulation and heat preservation functions prepared in Examples 1-3 and Comparative Examples 1-4. The performance tests included thermal conductivity, tensile strength, and bursting strength. The performance test results are shown in Table 1.

[0085] The thermal conductivity was detected according to the ASTM-D5470 standard test method for the materials prepared in the examples; the tensile properties were tested for the tensile strength of the materials prepared in the examples according to the ASTM D3039 / D3039M-14 standard; the bursting strength was carried out in accordance with the standard GB / T 6544-2008, and the test methods and sampling methods in the standard were implemented.

[0086] Table 1

[0087] Thermal conductivity (W / m*k) Tensile strength (MPa) Bursting strength (kPa) Example 1 0.0235 2.06 3920 Example 2 0.0261 2.05 3580 Example 3 0.0247 2.03 3745 Example 4 0.0251 2.04 3612 Example 5 0.0243 2.03 3540 Comparative example 1 0.0289 1.94 3100 Comparative example 2 0.0317 1.98 3220 Comparative example 3 0.0324 2.01 3150 Comparative example 4 0.0371 1.73 2530

[0088] The thermal conductivity of the thermal insulation material is one of the important indicators for evaluating the thermal insulation performance of the material. The smaller the thermal conductivity, the better the thermal insulation performance of the material. As can be seen from Table 1, the corrugated cardboard boxes prepared in the examples of the present invention are all less than 0.03W / m*k, and have excellent thermal insulation performance compared with the comparative documents. Since no heat insulation layer was added in Comparative Example 4, the thermal conductivity is much higher than that of the examples. Therefore, it can be shown that the cellulose-polyurethane composite aerogel provided by the present invention can effectively improve the thermal insulation performance of the corrugated cardboard box.

[0089] The bursting strength and tensile strength of the corrugated cardboard boxes prepared by the technical solutions described in the examples of the present invention both meet the standard requirements and are higher than those of the comparative examples. From this, it can be shown that the technical solutions provided by the present invention can not only improve the thermal insulation performance of the corrugated cardboard box, but also improve the mechanical strength of the corrugated cardboard box through the cellulose-polyurethane composite aerogel.

[0090] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A corrugated cardboard box with heat insulation and heat preservation functions, characterized in that, The corrugated cardboard box includes a face paper, a corrugated paper core, a heat insulation layer, and a lining paper that are stacked in sequence; wherein, the material of the heat insulation layer is cellulose-polyurethane composite aerogel, and the cellulose-polyurethane composite aerogel is prepared by the following steps: S1: Provide a cellulose pretreatment solution containing a cellulose source; S2: Add glycerol to the cellulose pretreatment solution and perform ultrasonic treatment to obtain a cellulose suspension; S3: Mix the cellulose suspension with polyurethane, and then add a crosslinking agent to react to obtain a cellulose-polyurethane composite sol, and the polyurethane is amino-terminated polyurethane or hydroxyl-terminated polyurethane; S4: Immerse the cellulose-polyurethane composite sol in a hydrophobic modifier; S5: Transfer the mixed system obtained in S4 to a freeze dryer and dry it at a temperature of -50 to -30°C and a pressure of 0.1-0.4 mbar to obtain a porous composite aerogel; S6: Hot press the porous composite aerogel and spray a polylactic acid solution to obtain the cellulose-polyurethane composite aerogel.

2. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, characterized in that, The cellulose source is selected from at least one of rice husk pulp, wood pulp, and cotton pulp.

3. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, wherein, In S1, the temperature of the treatment solution is 60-80°C and the reaction time is 2-3 h; in S2, the glycerol concentration is 0.4-0.7 wt%, the ultrasonic treatment time is 20-40 min, and the ultrasonic frequency is 30-50 kHz.

4. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 3, characterized in that, The treatment solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, and sodium bicarbonate solution.

5. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, characterized in that, In S3, after adding the crosslinking agent, react at 50-70°C for 40-60 min, the crosslinking agent concentration is 0.1-0.3 wt%, and the crosslinking agent is glutaraldehyde or glyoxal; in S4, after immersion in the hydrophobic modifier, let it stand for 22-26 h.

6. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 5, characterized in that, The hydrophobic modifier is selected from at least one of methyltrimethoxysilane, octyltriethoxysilane, cetyltrimethoxysilane, aminopropyltriethoxysilane, trichloromethylsilane, and methyldiethoxysilane.

7. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, wherein In S5, the drying time is 36-48 h; in S6, the hot pressing temperature is 60-80°C, the hot pressing pressure is 0.5-0.7 MPa, the hot pressing time is 8-12 min, and the concentration of the polylactic acid solution is 4-6 wt%.

8. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, characterized in that, The thickness of the cellulose-polyurethane composite aerogel is 2-3 mm.

9. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, characterized in that, In S6, the spraying thickness is 3-5 μm.

10. The corrugated cardboard box with heat insulation and heat preservation functions according to claim 1, characterized in that, In S3, the mass ratio of the cellulose suspension to polyurethane is 5-7:3.