阅读说明：本技术 一种保温环保食品包装盒及其生产方法 (Heat-preservation environment-friendly food packaging box and production method thereof ) 是由 刘瑞霞 于 2021-07-26 设计创作，主要内容包括：本发明公开了一种保温环保食品包装盒及其生产方法。本发明的保温环保食品包装盒,包括内胆和外盒,所述内胆设置在外盒内,内胆上沿与外盒上沿完全贴合,所述内胆和外盒之间设置有发热保温材料。本发明所制备的发热保温材料具有强吸水性能和保温性能,具有无毒无污染、轻质等优点,可以使得保温盒在很长时间维持较高的温度,同时制备得到的多功能材料还可以重复利用,节约原料,降低成本。(The invention discloses a heat-preservation environment-friendly food packaging box and a production method thereof. The heat-preservation environment-friendly food packaging box comprises an inner container and an outer box, wherein the inner container is arranged in the outer box, the upper edge of the inner container is completely attached to the upper edge of the outer box, and a heating and heat-preservation material is arranged between the inner container and the outer box. The heating and heat-insulating material prepared by the invention has strong water absorption performance and heat-insulating performance, has the advantages of no toxicity, no pollution, light weight and the like, can ensure that a heat-insulating box can maintain higher temperature for a long time, and meanwhile, the prepared multifunctional material can be recycled, thereby saving raw materials and reducing cost.)

1. The heat-insulating environment-friendly food packaging box comprises an inner container and an outer box, and is characterized in that a heat-insulating material is arranged between the inner container and the outer box.

2. The heat-insulating environment-friendly food packaging box according to claim 1, wherein the material of the outer box is antibacterial polyamide.

3. The heat-preservation environment-friendly food packaging box according to claim 2, wherein the inner container is made of one or a mixture of more than two of polypropylene, polyethylene and polyethylene.

4. The heat-insulating environment-friendly food packaging box according to claim 1, further comprising a box cover and a temperature sticker, wherein the box cover is made of antibacterial polyamide, and the temperature sticker is stuck on the box cover.

5. The heat-insulating environment-friendly food packaging box according to claim 1, wherein the heat-generating heat-insulating material is composed of the following raw materials: 50-65 wt% of iron powder, 3-8 wt% of sodium chloride, 1-4 wt% of alumina, 5-10 wt% of fly ash, 3-8 wt% of vermiculite, 1-5 wt% of tourmaline powder, 5-20 wt% of multifunctional material and the balance of water.

6. The heat-preserving and environment-friendly food packing box according to claim 5, wherein the multifunctional material is prepared by the following steps:

s1, mixing ferric acetylacetonate and ethylene glycol, and adding trisodium citrate and ammonium acetate to react to obtain carboxylated ferroferric oxide microspheres;

s2, dissolving the carboxylated ferroferric oxide microspheres in water, performing ultrasonic treatment, adding a hydroxyethyl methacrylate monomer and copper sulfate, stirring, and adding ammonium persulfate to obtain a mixed solution I;

and S3, placing the mixed solution I obtained in the step S2 in a carbon dioxide environment, and drying to obtain the multifunctional material.

7. The heat-preserving and environment-friendly food packing box according to claim 6, wherein the multifunctional material is prepared by the following steps:

s1, mixing ferric acetylacetonate and ethylene glycol, and adding trisodium citrate and ammonium acetate to react to obtain carboxylated ferroferric oxide microspheres;

s2, dissolving the carboxylated ferroferric oxide microspheres in water, performing ultrasonic treatment, adding a hydroxyethyl methacrylate monomer and copper sulfate, stirring, and adding ammonium persulfate to obtain a mixed solution I;

s3, mixing methyl orthosilicate, ethylene glycol, water, urea and a surfactant, adding methyltrimethoxysilane, and stirring to obtain silicon dioxide sol;

and S4, mixing the mixed solution I obtained in the step S2 and the silica sol obtained in the step S3 for reaction, and drying in a carbon dioxide environment to obtain the multifunctional material.

8. The heat-insulating environment-friendly food packaging box according to claim 7, wherein the surfactant is dodecyl dimethyl betaine and/or polyethylene glycol.

9. The heat-insulating environment-friendly food packaging box of claim 1, wherein the heat-generating heat-insulating material is arranged between the outer box and the bottom of the inner container or between the outer box and the side wall of the inner container.

10. The production method of the heat-insulating environment-friendly food packing box according to any one of claims 1 to 9, comprising the steps of:

(1) outer box and lid: preparing the outer box and the box cover from the antibacterial polyamide by a conventional injection molding process;

(2) an inner container: preparing the inner container from polypropylene by a conventional injection molding process;

(3) firstly, the heating and heat-insulating material is put into the outer box, then the inner container is put into the outer box, and the box cover is covered to obtain the heat-insulating environment-friendly food packaging box.

Technical Field

The invention relates to the technical field of food packaging, in particular to a heat-preservation and environment-friendly food packaging box and a production method thereof.

Background

The plastic packing boxes commonly used in the prior restaurants can not keep the food at the proper temperature for a long time, and the problem that whether a hot meal can be eaten or not is a big problem. Stomach is very critical to food, and raw, hard, cold, sour, spicy and other pungent foods can affect the work of stomach. Proper temperature is required for normal work of a plurality of digestive enzymes, and gastric acid secretion and the effects of the digestive enzymes can be influenced if people eat cold dishes for a long time. In the past, stomach diseases such as gastric ulcer and superficial gastritis may be affected.

Chinese patent (application number: 202010511901.2) discloses an environment-friendly biodegradable food packaging box, which is prepared from the following raw materials: the raw materials comprise the following components in parts by weight: 30-45 parts of sweet potato starch, 8-12 parts of hydroxypropyl methyl cellulose, 1-2 parts of a plant fiber modifier, 3-8 parts of an antibacterial solvent, 4-6 parts of polyethylene glycol, 1-2 parts of emulsifying gum, 0.05-0.1 part of cellulase, 1-3 parts of polyalcohol, 6-8 parts of chitosan and 6-8 parts of a composite filler.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a heat-preservation and environment-friendly food packaging box and a production method thereof.

In order to solve the technical problems, the invention adopts the technical scheme that:

the heat-insulating environment-friendly food packaging box comprises an inner container and an outer box, wherein a heat-insulating material is arranged between the inner container and the outer box.

The outer box is made of antibacterial polyamide.

The material of the inner container is any one or a mixture of more than two of polypropylene, polyethylene and polyethylene.

The heat-preservation environment-friendly food packaging box further comprises a box cover and a temperature sticker, the box cover is made of antibacterial polyamide, and the temperature sticker is pasted on the box cover.

The temperature paster can display the temperature within the range of 30-80 ℃.

The heating and heat-insulating material is composed of the following raw materials: 50-65 wt% of iron powder, 3-8 wt% of sodium chloride, 1-4 wt% of alumina, 5-10 wt% of fly ash, 3-8 wt% of vermiculite, 1-5 wt% of tourmaline powder, 5-20 wt% of multifunctional material and the balance of water.

The preparation method of the heating and heat-insulating material comprises the following steps: weighing raw materials in proportion, mixing without gravity, placing into a non-woven fabric bag, covering with a gas-impermeable and water-impermeable gelatin bag, vacuumizing, and sealing.

Ferroferric oxide gel is superior to ferroferric oxide gel in stronger magnetism because of wide application, but most ferroferric oxide gel is applied to the aspects of cancer thermotherapy, drug release control, microfluidics and the like. In order to increase the functionality, researchers add photosensitive components such as Au nanorods and graphene into the magnetic composite hydrogel. This combines magnetic properties with the ability to convert Near Infrared (NIR) absorption to heat, providing the possibility of simultaneous imaging and multiple therapy control. However, the application research of the ferroferric oxide gel in the aspects of water absorption and heat preservation is very little, and the application of the ferroferric oxide gel is also limited.

The invention discovers that a hydroxyethyl methacrylate monomer grafted on the surface of a ferroferric oxide microsphere can generate free radical polymerization reaction under certain conditions, a macromolecular nano brush-shaped gel factor is grafted on the surface of a carboxylated ferroferric oxide microsphere with a reactive functional group, and the gel factor is prepared by the following physical interaction between grafting chains: the gel network is constructed by the interaction of hydrogen bonds, hydrophobic interaction, electrostatic interaction, coordination and the like, the hydrogel which has excellent mechanical property and very strong water absorption property is prepared, and the prepared ferroferric oxide gel has a porous structure, has a relatively large specific surface area, has very strong adsorption property, can store certain energy and stably and uniformly releases heat, so that the heat preservation box has a long heat preservation time.

Specifically, (1) preparing carboxylated ferroferric oxide microspheres by a hydrothermal method; (2) dispersing the carboxylated ferroferric oxide microspheres with the reactive functional groups in water, and then sequentially adding a hydroxyethyl methacrylate monomer, inorganic salt copper sulfate and initiator ammonium persulfate, wherein the addition of the inorganic salt copper sulfate is favorable for improving the efficiency of preparing the high-molecular hydrogel to obtain a mixed solution; (3) and introducing inert gas carbon dioxide into the raw material mixed solution, and grafting the hydroxyethyl methacrylate monomer on the surface of the carboxylated ferroferric oxide microsphere with the reactive functional group under a certain condition to obtain the multifunctional material.

The preparation method of the multifunctional material comprises the following steps:

s1, mixing ferric acetylacetonate and ethylene glycol, and adding trisodium citrate and ammonium acetate to react to obtain carboxylated ferroferric oxide microspheres;

s2, dissolving the carboxylated ferroferric oxide microspheres in water, performing ultrasonic treatment, adding a hydroxyethyl methacrylate monomer and copper sulfate, stirring, and adding ammonium persulfate to obtain a mixed solution I;

s3, placing all the mixed solution I obtained in the step S2 in a carbon dioxide environment, and drying to obtain the multifunctional material.

Preferably, the preparation method of the multifunctional material is as follows:

s1, mixing 0.5-2 parts by weight of ferric acetylacetonate and 30-50 parts by weight of ethylene glycol, stirring at room temperature and 1000rpm for 20-50min, adding 0.1-1 part by weight of trisodium citrate and 1-5 parts by weight of reducing agent ammonium acetate, continuously stirring for 15-30min, transferring to a reaction kettle, carrying out hydrothermal reaction at 150 ℃ and 180 ℃ for 8-16h, centrifuging, washing, and carrying out vacuum drying at 60-80 ℃ for 10-20h to obtain carboxylated ferroferric oxide microspheres;

s2, dissolving 0.5-3 parts by weight of the carboxylated ferroferric oxide microspheres in 80-120 parts by weight of water, performing ultrasonic treatment at the ultrasonic power of 100-300W and the ultrasonic frequency of 20-60kHz for 20-50min, adding 1-5 parts by weight of hydroxyethyl methacrylate monomer and 0.1-1 part by weight of copper sulfate, stirring at the ultrasonic frequency of 400rpm of 200-1 for 5-20min, adding 0.01-0.1 part by weight of initiator ammonium persulfate, and continuously stirring for 5-15min to obtain a mixed solution I;

s3, placing all the mixed solution I obtained in the step S2 under the protection of nitrogen, reacting for 15-30h at 40-80 ℃, placing the mixture in a carbon dioxide environment after the reaction is finished, and drying for 4-10h under the conditions of 10-16MPa of pressure and 70-90 ℃ to obtain the multifunctional material.

The silica sol not only has low thermal conductivity and good insulativity, but also has good stability, and can be stably stored for several days at normal temperature, so the silica sol gel is compounded to the heating and heat-insulating material with good water absorption performance, and the heat-insulating performance of the heating and heat-insulating material can be further improved.

Specifically, the multifunctional material is prepared by preparing silica sol in S3, mixing the obtained mixed solution containing the carboxylated ferroferric oxide microspheres with all the silica sol obtained in S3, heating and reacting under the protection of nitrogen, decomposing the silica sol into gel by urea, and reacting the hydroxyl-containing surfactant on the surface of the silica gel with the carboxyl on the surface of the ferroferric oxide.

The dodecyl dimethyl betaine has good foamability and dispersibility, the expansion rate of the silicon dioxide gel is improved, and the heat insulation performance is improved; the polyethylene glycol has good hydrophilicity, moisture retention, dispersibility and cohesiveness, can effectively improve the binding property with the ferroferric oxide gel, further improve the stability of the multifunctional material, and simultaneously can change the hydrophilicity of the surface of the silicon dioxide particles and increase the water absorption property after the surface of the silicon dioxide gel is modified, so that the hydrophilicity and the water absorption property are improved, and the two are synergistic to jointly improve the heat insulation property of the multifunctional material.

Further, the preparation method of the multifunctional material comprises the following steps:

s1, mixing ferric acetylacetonate and ethylene glycol, and adding trisodium citrate and ammonium acetate to react to obtain carboxylated ferroferric oxide microspheres;

s2, dissolving the carboxylated ferroferric oxide microspheres in water, performing ultrasonic treatment, adding a hydroxyethyl methacrylate monomer and copper sulfate, stirring, and adding ammonium persulfate to obtain a mixed solution I;

s3, mixing methyl orthosilicate, ethylene glycol, water, urea and a surfactant, adding methyltrimethoxysilane, and stirring to obtain silicon dioxide sol;

and S4, mixing the mixed solution I obtained in the step S2 and the silica sol obtained in the step S3 for reaction, and drying in a carbon dioxide environment to obtain the multifunctional material.

Preferably, the preparation method of the multifunctional material is as follows:

s1, mixing 0.5-2 parts by weight of ferric acetylacetonate and 30-50 parts by weight of ethylene glycol, stirring at room temperature and 1000rpm for 20-50min, adding 0.1-1 part by weight of trisodium citrate and 1-5 parts by weight of reducing agent ammonium acetate, continuously stirring for 15-30min, transferring to a reaction kettle, carrying out hydrothermal reaction at 150 ℃ and 180 ℃ for 8-16h, centrifuging, washing, and carrying out vacuum drying at 60-80 ℃ for 10-20h to obtain carboxylated ferroferric oxide microspheres;

s2, dissolving 0.5-3 parts by weight of the carboxylated ferroferric oxide microspheres in 80-120 parts by weight of water, performing ultrasonic treatment at the ultrasonic power of 100-300W and the ultrasonic frequency of 20-60kHz for 20-50min, adding 1-5 parts by weight of hydroxyethyl methacrylate monomer and 0.1-1 part by weight of copper sulfate, stirring at the ultrasonic frequency of 400rpm of 200-1 for 5-20min, adding 0.01-0.1 part by weight of initiator ammonium persulfate, and continuously stirring for 5-15min to obtain a mixed solution I;

s3, mixing 50-70 parts by weight of methyl orthosilicate, 10-30 parts by weight of ethylene glycol, 5-15 parts by weight of water, 1-4 parts by weight of urea and 1-4 parts by weight of surfactant, adjusting the pH to 4.5-6 by using 1-3mol/L hydrochloric acid, stirring for 20-40min at 500rpm of 300-;

and S4, mixing all the mixed solution I obtained in the step S2 with all the silica sol obtained in the step S3, reacting for 15-30h at 40-80 ℃ under the protection of nitrogen, placing in a carbon dioxide environment after the reaction is finished, and drying for 4-10h under the conditions of 10-16MPa of pressure and 70-90 ℃ to obtain the multifunctional material.

The surfactant is dodecyl dimethyl betaine and/or polyethylene glycol; preferably, the surfactant is composed of dodecyl dimethyl betaine and polyethylene glycol according to a mass ratio of (1-3) to (1-3).

The heating and heat-insulating material can be arranged between the outer box and the bottom of the inner container or between the outer box and the side wall of the inner container.

The production method of the heat-preservation environment-friendly food packaging box comprises the following steps:

(1) outer box and lid: preparing the outer box and the box cover from the antibacterial polyamide by a conventional injection molding process;

(2) an inner container: preparing the inner container from polypropylene by a conventional injection molding process;

(3) firstly, the heating and heat-insulating material is put into the outer box, then the inner container is put into the outer box, and the box cover is covered to obtain the heat-insulating environment-friendly food packaging box.

The invention has the beneficial effects that:

1. the multifunctional material prepared by the invention has strong water absorption and heat insulation performance, has the advantages of no toxicity, no pollution, light weight and the like, not only has low heat conductivity coefficient, but also has higher water absorption, can ensure that the heat insulation box can maintain higher temperature for a long time, and can be repeatedly utilized, thereby saving raw materials and reducing cost.

2. The heat-preservation environment-friendly food packaging box prepared by the invention has the advantages of low cost, simple and convenient operation, easily obtained raw materials and the like, is suitable for large-scale industrial production, and has a wide application range.

Detailed Description

The above summary of the present invention is described in further detail below with reference to specific embodiments, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples.

Introduction of some raw materials in this application:

antibacterial polyamide is purchased from the company of huge and positive new material science and technology (Dongguan), and the trade name is as follows: 22 CBK.

Polypropylene was purchased from kay pigeon plastification ltd, yao city, brand: T30S.

Iron powder is available from Shandong Bai Qian chemical Co., Ltd., reduced iron powder, 200 mesh.

The fly ash is purchased from Jiagong mineral products, Inc. of Lingshu county, 325 meshes.

Tourmaline powder was purchased from Cilong mineral processing factory, Lingshui county, 1250 mesh.

Vermiculite was purchased from mineral processing factory built in Guishou county, 100 mesh.

Polyethylene glycol was purchased from southern high-k chemical company, model number: PEG 4000.

Gelatin bags were purchased from the Foshan, Lilin packaging technologies, Inc., type: 2010.

the non-woven fabric is purchased from Jinhaochen non-woven fabrics Co Ltd of Huizhou city, and the gram weight is 40g/m²。

Temperature paster Cao doctor's temperature measuring paste purchased from Guangzhou gold core temperature measuring paste manufacturing plant.

Example 1

A heat-insulating environment-friendly food packaging box comprises an inner container, an outer box and a box cover, wherein a heating heat-insulating material is arranged between the inner container and the outer box;

the outer box and the box cover are both made of antibacterial polyamide;

the inner container is made of polypropylene.

The heating and heat-insulating material is composed of the following raw materials: 60 wt% of iron powder, 5 wt% of sodium chloride, 2 wt% of alumina, 6 wt% of fly ash, 5 wt% of vermiculite, 2 wt% of tourmaline powder and the balance of water;

the preparation method of the heating and heat-insulating material comprises the following steps: weighing raw materials in proportion, mixing in gravity-free machine (model WZ-0.1, Shenglong chemical machinery Co., Ltd., Lyzhou city) for 3min, putting 45g of the mixed material into a 10cm × 10cm × 0.5cm non-woven fabric bag, covering with an air-tight and water-tight gelatin bag, vacuumizing, and sealing to obtain the final product.

The production method of the heat-preservation environment-friendly food packaging box comprises the following steps:

(1) outer box and lid: preparing the outer box and the box cover from the antibacterial polyamide by a conventional injection molding process; the size of the inner edge of the upper surface of the outer box is 18cm multiplied by 18cm, the size of the inner edge of the bottom is 12cm multiplied by 12cm, and the height is 8 cm;

(2) an inner container: preparing the inner container from polypropylene by a conventional injection molding process; the size of the inner container is prepared according to the following requirements: controlling the size of a cavity between the outer box and the side wall of the inner container to be 1.8mm (namely the vertical distance between the outer box and the side wall of the inner container is 1.8mm), and controlling the size of a gap between the outer box and the bottom of the inner container to be 0.6cm (namely the vertical distance between the outer box and the bottom of the inner container is 0.6 cm); the thicknesses of the outer box, the inner container and the box cover are all 1 mm;

(3) firstly, the heating and heat-insulating material is put into the outer box, then the inner container is put into the outer box, and the box cover is covered to obtain the heat-insulating environment-friendly food packaging box.

The box cover is provided with a temperature sticker capable of displaying temperature.

The temperature sticker can display a temperature within the range of 30-80 ℃.

Example 2

A heat-insulating environment-friendly food packaging box comprises an inner container, an outer box and a box cover, wherein a heating heat-insulating material is arranged between the inner container and the outer box;

the outer box and the box cover are both made of antibacterial polyamide;

the inner container is made of polypropylene.

The heating and heat-insulating material is composed of the following raw materials: 60 wt% of iron powder, 5 wt% of sodium chloride, 2 wt% of alumina, 6 wt% of fly ash, 5 wt% of vermiculite, 2 wt% of tourmaline powder, 8 wt% of multifunctional material and the balance of water;

the preparation method of the heating and heat-insulating material comprises the following steps: weighing raw materials in proportion, mixing in a gravity-free machine (model WZ-0.1, Shenglong chemical machinery Co., Ltd., Lyzhou city) for 3min, putting 45g of the mixed material into a 10cm × 10cm × 0.5cm non-woven fabric bag, wherein the non-woven fabric bag is made of a microporous breathable film, covering with a breathable and waterproof gelatin bag, vacuumizing, and sealing to obtain the product.

The preparation method of the multifunctional material comprises the following steps:

s1, mixing 1 weight part of ferric acetylacetonate and 40 weight parts of glycol, stirring at room temperature and 800rpm for 30min, adding 0.15 weight part of trisodium citrate and 3 weight parts of reducing agent ammonium acetate, continuously stirring for 20min, transferring to a reaction kettle, carrying out hydrothermal reaction at 160 ℃ for 12h, centrifuging, washing, and carrying out vacuum drying at 70 ℃ for 12h to obtain the carboxylated ferroferric oxide microspheres;

s2, dissolving 0.8 part by weight of the carboxylated ferroferric oxide microspheres in 100 parts by weight of water, performing ultrasonic treatment for 30min at an ultrasonic frequency of 35kHz and an ultrasonic power of 300W, adding 3 parts by weight of hydroxyethyl methacrylate monomer and 0.5 part by weight of copper sulfate, stirring for 10min at 300rpm, adding 0.05 part by weight of initiator ammonium persulfate, and continuing stirring for 10min to obtain a mixed solution I;

and S3, placing all the mixed solution I obtained in the step S2 under the protection of nitrogen, reacting for 20 hours at 60 ℃, placing the mixture in a carbon dioxide environment after the reaction is finished, and drying for 5 hours under the conditions of pressure of 12MPa and 85 ℃ to obtain the multifunctional material.

The production method of the heat-preservation environment-friendly food packaging box comprises the following steps:

(1) outer box and lid: preparing the outer box and the box cover from the antibacterial polyamide by a conventional injection molding process; the size of the inner edge of the upper surface of the outer box is 18cm multiplied by 18cm, the size of the inner edge of the bottom is 12cm multiplied by 12cm, and the height is 8 cm;

(2) an inner container: preparing the inner container from polypropylene by a conventional injection molding process; the size of the inner container is prepared according to the following requirements: controlling the size of a cavity between the outer box and the side wall of the inner container to be 1.8mm (namely the vertical distance between the outer box and the side wall of the inner container is 1.8mm), and controlling the size of a gap between the outer box and the bottom of the inner container to be 0.6cm (namely the vertical distance between the outer box and the bottom of the inner container is 0.6 cm); the thicknesses of the outer box, the inner container and the box cover are all 1 mm;

(3) firstly, the heating and heat-insulating material is put into the outer box, then the inner container is put into the outer box, and the box cover is covered to obtain the heat-insulating environment-friendly food packaging box.

The box cover is provided with a temperature sticker capable of displaying temperature.

The temperature sticker can display a temperature within the range of 30-80 ℃.

Example 3

A heat-insulating environment-friendly food packaging box comprises an inner container, an outer box and a box cover, wherein a heating heat-insulating material is arranged between the inner container and the outer box;

the outer box and the box cover are both made of antibacterial polyamide;

the inner container is made of polypropylene.

The heating and heat-insulating material is composed of the following raw materials: 60 wt% of iron powder, 5 wt% of sodium chloride, 2 wt% of alumina, 6 wt% of fly ash, 5 wt% of vermiculite, 2 wt% of tourmaline powder, 8 wt% of multifunctional material and the balance of water;

the preparation method of the heating and heat-insulating material comprises the following steps:

weighing raw materials in proportion, mixing in a gravity-free machine (model WZ-0.1, Shenglong chemical machinery Co., Ltd., Lyzhou city) for 3min, putting 45g of the mixed material into a 10cm × 10cm × 0.5cm non-woven fabric bag, wherein the non-woven fabric bag is made of a microporous breathable film, covering with a breathable and waterproof gelatin bag, vacuumizing, and sealing to obtain the product.

The preparation method of the multifunctional material comprises the following steps:

s1, mixing 1 weight part of ferric acetylacetonate and 40 weight parts of glycol, stirring at room temperature and 800rpm for 30min, adding 0.15 weight part of trisodium citrate and 3 weight parts of reducing agent ammonium acetate, continuously stirring for 20min, transferring to a reaction kettle, carrying out hydrothermal reaction at 160 ℃ for 12h, centrifuging, washing, and carrying out vacuum drying at 70 ℃ for 12h to obtain the carboxylated ferroferric oxide microspheres;

s2, dissolving 0.8 part by weight of the carboxylated ferroferric oxide microspheres in 100 parts by weight of water, performing ultrasonic treatment for 30min at an ultrasonic frequency of 35kHz and an ultrasonic power of 300W, adding 3 parts by weight of hydroxyethyl methacrylate monomer and 0.5 part by weight of copper sulfate, stirring for 10min at 300rpm, adding 0.05 part by weight of initiator ammonium persulfate, and continuing stirring for 10min to obtain a mixed solution I;

s3, mixing 60 parts by weight of methyl orthosilicate, 20 parts by weight of ethylene glycol, 10 parts by weight of water, 2 parts by weight of urea and 2 parts by weight of surfactant, adjusting the pH to 5 by using 2mol/L hydrochloric acid, stirring at 400rpm for 30min, adding 10 parts by weight of methyltrimethoxysilane, and continuing to stir at 80 ℃ for 30min to obtain silicon dioxide sol;

and S4, mixing all the mixed solution I obtained in the step S2 with all the silica sol obtained in the step S3, reacting for 20 hours at 60 ℃ under the protection of nitrogen, placing in a carbon dioxide environment after the reaction is finished, and drying for 5 hours under the conditions of pressure of 12MPa and 85 ℃ to obtain the multifunctional material.

The surfactant is dodecyl dimethyl betaine.

The production method of the heat-preservation environment-friendly food packaging box comprises the following steps:

(1) outer box and lid: preparing the outer box and the box cover from the antibacterial polyamide by a conventional injection molding process; the size of the inner edge of the upper surface of the outer box is 18cm multiplied by 18cm, the size of the inner edge of the bottom is 12cm multiplied by 12cm, and the height is 8 cm;

(2) an inner container: preparing the inner container from polypropylene by a conventional injection molding process; the size of the inner container is prepared according to the following requirements: controlling the size of a cavity between the outer box and the side wall of the inner container to be 1.8mm (namely the vertical distance between the outer box and the side wall of the inner container is 1.8mm), and controlling the size of a gap between the outer box and the bottom of the inner container to be 0.6cm (namely the vertical distance between the outer box and the bottom of the inner container is 0.6 cm); the thicknesses of the outer box, the inner container and the box cover are all 1 mm;

(3) firstly, the heating and heat-insulating material is put into the outer box, then the inner container is put into the outer box, and the box cover is covered to obtain the heat-insulating environment-friendly food packaging box.

The box cover is provided with a temperature sticker capable of displaying temperature.

The temperature sticker can display a temperature within the range of 30-80 ℃.

Comparative example 1

The same as in example 3, except that the multifunctional material was prepared as follows:

s1, mixing 60 parts by weight of methyl orthosilicate, 20 parts by weight of ethylene glycol, 10 parts by weight of water, 2 parts by weight of urea and 2 parts by weight of surfactant, adjusting the pH to 5 by using 2mol/L hydrochloric acid, stirring at 400rpm for 30min, adding 10 parts by weight of methyltrimethoxysilane, and continuing to stir at 80 ℃ for 30min to obtain silicon dioxide sol;

and S2, placing the silica sol obtained in the step S1 under the protection of nitrogen, reacting for 20 hours at 60 ℃, placing the obtained product in a carbon dioxide environment after the reaction is finished, and drying for 5 hours under the conditions of pressure of 12MPa and 85 ℃ to obtain the multifunctional material.

The surfactant is dodecyl dimethyl betaine.

Example 4

The same as in example 3, except that the surfactant was polyethylene glycol.

Example 5

The same as example 3, except that the surfactant was composed of dodecyl dimethyl betaine and polyethylene glycol in a mass ratio of 1: 1.

Test example 1

And (3) testing the temperature rising and reducing characteristics: the heating and cooling characteristics of the heat-generating and heat-insulating materials obtained in examples 1 to 5 and comparative example 1 were measured. The test method is as follows: tearing off the outer belt of the heating and heat-insulating material, placing the non-woven fabric inner bag in an environment with the temperature of 25 ℃ and the relative humidity of 45%, testing the surface temperature of the middle center of the heating and heat-insulating material every 1 minute, recording the highest surface temperature, the time (min) for reaching the highest temperature, the time (min) for lasting over 45 ℃ and the time required for recovering to 25 ℃, testing 3 times in each group, and averaging, wherein the test results are shown in table 1.

TABLE 1 test of temperature rising and lowering characteristics

From the results in table 1, it can be seen that the heat preservation time of the packaging box can be prolonged by adding the heating and heat-insulating material into the heat preservation and environment-friendly food packaging box, and the maximum temperature is not greatly affected, but the time for reaching the maximum temperature is prolonged because the added multifunctional material is in a gel foaming state, has a certain heat insulation property and a relatively low thermal conductivity, and the heat conduction speed is slowed down, so the time for reaching the maximum heat preservation is prolonged to a certain extent; then the heat preservation time is greatly improved after the heating and heat preservation material is added, the time lasting for more than 45 ℃ is obviously prolonged, and the time required for recovering to 25 ℃ is also longer, the reason is that the ferroferric oxide gel has very strong water absorption performance, and the prepared ferroferric oxide gel has a porous structure, has a larger specific surface area, has very strong adsorption performance, can store certain energy and stably and uniformly release heat, so that the heat preservation box has longer heat preservation time, and the silica sol not only has low thermal conductivity, good insulativity and good stability, can be stably stored for a plurality of days at normal temperature, therefore, the silica sol gel is compounded to the heating and heat preservation material with good water absorption performance, the heat preservation performance of the heating and heat preservation material can be further improved, the two are synergistic, the heat preservation time is prolonged.

Comparing examples 3-5, example 5 adding the surfactants dodecyl dimethyl betaine and polyethylene glycol can further prolong the holding time; the reason is that the dodecyl dimethyl betaine has good foamability and dispersibility, the expansion rate of the silicon dioxide gel is improved, and the heat preservation performance is improved; the polyethylene glycol has good hydrophilicity, moisture retention, dispersibility and cohesiveness, can effectively improve the binding property with the ferroferric oxide gel, further improve the stability of the multifunctional material, and simultaneously can change the hydrophilicity of the surface of the silicon dioxide particles and increase the water absorption property after the surface of the silicon dioxide gel is modified, so that the heat preservation property of the multifunctional material is improved and the heat preservation time is further prolonged.

Test example 2

Testing the heat release performance: DSC experiments were performed on the exothermic and thermal insulating materials obtained in examples 1 to 5 and comparative example 1, with a sample weight of 3.05mg, and the exothermic amounts of the reactions at different temperatures were obtained by integrating the DSC curves, and based thereon, similar ratios were calculated, averaged for 3 times, and the results of the experiments were shown in Table 2.

TABLE 2 exothermic value test results

From the above results, it was confirmed that the heat-generating and heat-insulating material was added to further prolong the heat-insulating time, but in example 1, the multifunctional material was not added, and the energy released in the same time was more increased under the same conditions for generating the same energy, and thus the temperature was more easily returned to the normal temperature, and the heat-insulating time was longer because the energy was slowly released after the multifunctional material was added.

Test example 3

Testing the heat preservation performance: 3kg of cooked rice with the temperature of 50 ℃ and the water content of 60 percent are respectively filled in the inner containers of the heat-preservation environment-friendly food packaging boxes of the embodiments 1 to 5 and the comparative example 1, the gelatin bag of the heating and heat-preservation material is torn, the non-woven fabric inner bag is placed in the cavity at the bottom and the side between the outer box and the bottom of the inner container, the box cover is covered, the packaging box is placed in the environment with the temperature of 15 ℃ and the relative humidity of 50 percent, the box cover is opened after 1.5h, the temperature at the center of the cooked rice is tested by an electronic temperature gun, and the heat-preservation performance of the heat-preservation environment-friendly food packaging box is tested. The heat-preservation environment-friendly food packaging boxes described in each example were tested 8 times each, and the average value was taken as the final data.

TABLE 3 Heat insulation Performance test results

From the above table 3, it can be seen that the heat-generating and heat-insulating material prepared by the present invention has good heat-insulating properties, and the temperature of the cooked rice in the examples 3-5 is increased after being placed for 1.5h, because the package box is placed in an environment with a humidity of 50%, the non-woven fabric bag is exposed to the air with a relative humidity, oxygen in the air enters the non-woven fabric bag through the air-permeable film, iron in the non-woven fabric bag serves as a negative electrode, oxygen in the air serves as a positive electrode to form a galvanic cell, and a galvanic cell reaction occurs to convert chemical energy into heat energy, whereas the multifunctional material prepared by the present invention has water-absorbing, heat-insulating properties, the carboxylated ferroferric oxide gel has water-absorbing properties, and the silica gel has heat-insulating properties, a part of generated water vapor with heat can be stored in the voids of the multifunctional material, and is slowly released through the voids in the multifunctional material and the non-woven fabric, thereby slowing the temperature drop.