A heat resistant paper bowl

Abstract

This application discloses a heat-resistant paper bowl, comprising a body with an opening at the top and a heat-resistant layer attached to the outside of the body. The heat-resistant layer is obtained by laminating a heat-resistant coating, which comprises the following raw materials in parts by weight: 100 parts polysiloxane, 34-42 parts tetraethyl orthosilicate, 14-20 parts ethanol, 0.5-0.7 parts alkali, 23-32 parts water, and 30-39 parts inorganic filler. The coating has both heat resistance and suitable thermal conductivity, allowing the paper bowl to be heated by a heat source.

Description

Technical Field

[0001] This application relates to containers, and more particularly to a heat-resistant paper bowl. Background Technology

[0002] Paper bowls are made of cardboard or paper. A waterproof membrane is usually attached to the inner layer of the formed paper to prevent water from seeping into the paper food container.

[0003] If paper bowls are heated in a microwave or electric oven, the paper material is easily damaged, deformed, or even charred and ignited. Therefore, for paper bowls that require heating or even secondary heating, it is necessary to improve their heat resistance to ensure the stability and safety of the paper bowl during the heating process. Summary of the Invention

[0004] To achieve stable heating and temperature rise of the paper bowl and to heat the contents, a heat-resistant paper bowl is provided.

[0005] The above-mentioned objective of this invention is achieved through the following technical solutions: A heat-resistant paper bowl includes a body with an opening at the top and a heat-resistant layer attached to the outside of the body. The heat-resistant layer is obtained by laminating a heat-resistant coating, and the heat-resistant coating comprises the following raw materials in parts by weight: 100 parts of polysiloxane 34-42 parts of tetraethyl orthosilicate 14-20 parts of ethanol 0.5-0.7 parts alkali, 23-32 parts water 30-39 parts of inorganic filler.

[0006] By employing the above technical solution, tetraethyl orthosilicate undergoes alcoholysis in ethanol, followed by polymerization with polysiloxane to form polysiloxanes with longer molecular chains. After drying and curing, these polysiloxanes exhibit excellent heat resistance. Inorganic fillers have free hydroxyl groups on their surface, which have good compatibility with polysiloxanes. When mixed into coatings, they enhance the adhesion of the coatings to the paper surface, making the coating easier to apply. Furthermore, appropriately proportioned inorganic fillers fill the cured polysiloxanes, reducing the porosity in the cured coating and thus improving the thermal conductivity of the cured polysiloxanes. This allows the coating to have both heat resistance and suitable thermal conductivity, enabling the paper cup to be heated by a heat source.

[0007] Optionally, the inorganic filler includes aluminum powder, which accounts for 40-55% of the mass of the inorganic filler.

[0008] By adopting the above technical solution, the inorganic filler also includes aluminum powder, which enables the paper bowl to be heated by electromagnetic eddy current.

[0009] Optionally, the aluminum powder has a particle size of 10~20μm.

[0010] By adopting the above technical solution, the aluminum powder particles at this particle size are more evenly distributed, and the electromagnetic eddy current heating speed is faster.

[0011] Optionally, the inorganic filler further includes alumina, wherein the alumina accounts for 45-60% of the mass of the inorganic filler.

[0012] By adopting the above technical solution, alumina has high strength and a porous surface with a large specific surface area. After being added, it has good bonding strength with polymeric siloxane, which effectively improves the coating strength and prevents the coating from peeling off due to scratches. Additionally, it can temporarily store water and ethanol in the coating during the drying process, making the polysiloxane shrink more densely during curing, reducing the internal pores after curing, and improving the thermal conductivity of the coating.

[0013] Optionally, the inorganic filler is alumina-coated aluminum powder microparticles, and the particle size of the inorganic filler is 40~50μm.

[0014] By adopting the above technical solution, aluminum powder is coated with alumina to prevent the aluminum powder from directly contacting or being exposed to the paper, thereby avoiding the possibility of burns caused by human hand contact after electromagnetic eddy current heating.

[0015] Optionally, the inorganic filler is prepared as follows: The aluminum powder was cleaned with an alkaline solution, then added to aluminum hydroxide gel, mixed thoroughly, dried, and granulated to obtain a dried material. The dried material was heated to 300℃, dehydrated to constant weight, and then ball-milled and sieved to obtain inorganic filler.

[0016] By adopting the above technical solution, aluminum powder is cleaned with alkaline solution to remove any oil stains that may remain on the surface, thereby activating the aluminum powder surface and generating trace amounts of aluminum hydroxide on the surface due to the galvanic cell reaction. This enhances the adhesion activity of aluminum oxide to aluminum powder, resulting in good coating effect of aluminum oxide on aluminum powder, and good bonding strength between inorganic filler and cured polymeric siloxane.

[0017] Optional: Also includes octenyl succinic acid starch.

[0018] By adopting the above technical solution, octenyl succinic acid starch improves the film-forming properties of the coating, and when the paper bowl is overheated during the heating process, the carbonization volume expands, forming heat-insulating voids, which prevent the heat source from continuing to heat the paper bowl, thus playing a safety protection role.

[0019] Optional: The heat-resistant layer on the side of the body is covered with a side coating.

[0020] By adopting the above technical solution, the tactile feel of the paper bowl's side can be adjusted, and oil stains on the side can be avoided from affecting its appearance.

[0021] In summary, this application has at least the following beneficial effects: 1. The coating has both heat resistance and suitable thermal conductivity, allowing the paper bowl to be heated by a heat source; at the same time, the inorganic filler also includes aluminum powder, which allows the paper bowl to be heated by electromagnetic eddy currents. 2. Aluminum powder is coated with alumina to prevent it from coming into direct contact with or being exposed to the paper. This avoids the possibility of burns from human touch after electromagnetic eddy current heating, while also effectively improving the coating strength, preventing the coating from peeling off due to scratches, reducing the internal pores after the polymeric siloxane has cured, and improving the thermal conductivity of the coating. Attached image description: Figure 1 This is a structural diagram of a paper bowl; Figure 2 for Figure 1 A magnified view of a portion at point A.

[0022] Figure label: 1. Body; 2. Heat-resistant layer; 3. Side coating. Detailed Implementation

[0023] Unless otherwise specified, the raw materials used in this application are commercially available products. For details on the specifications of the raw materials, please refer to the specific examples.

[0024] Preparation Example 1 A heat-resistant coating comprising the following raw materials: 100 kg of polysiloxane, 40 kg of tetraethyl orthosilicate, 17 kg of ethanol, 0.6 kg of alkali, 28 kg of water, and 36 kg of inorganic filler.

[0025] The polysiloxane is a linear methoxy polysiloxane with a relative molecular weight of 3000.

[0026] The alkali is sodium hydroxide, but potassium hydroxide can also be used in other implementations. The inorganic filler is a composite filler, specifically a powder formed by aluminum powder particles coated with alumina, with an overall particle size of 45±5μm, of which the aluminum powder particle size is 15±5μm.

[0027] The preparation method of inorganic fillers is as follows: The surface of aluminum powder was cleaned with an alkaline solution, and then added to an aluminum hydroxide gel with a water content of 24.3 wt%. The mass ratio of aluminum powder to aluminum hydroxide was 50:76.5. After uniform mixing, the mixture was dried and granulated to obtain a dried material. The dried material was heated to 300℃, dehydrated to constant weight, and then ball-milled and sieved to obtain inorganic filler.

[0028] The alkaline solution is a 0.1 mol / L sodium hydroxide solution; in other implementations, a 0.1 mol / L potassium hydroxide solution may also be used. The aluminum hydroxide gel is obtained by adding ammonia to an aluminum chloride solution to form a flocculent precipitate, followed by washing with water to remove ammonium ions.

[0029] The preparation method of heat-resistant coating is as follows: Mix alkali and water at a ratio of 1:12 to form an alkali solution. Mix polysiloxane, tetraethyl orthosilicate, ethanol, alkali, remaining water, and inorganic filler evenly and stir continuously until the material viscosity reaches 6000 cps. Then add alkali solution, mix evenly, and stir to obtain the heat-resistant coating.

[0030] Preparation Example 2 A heat-resistant coating differs from Preparation Example 1 in that the inorganic filler is an equal mass of alumina powder with a particle size of 45±5μm.

[0031] Preparation Example 3 A heat-resistant coating differs from Preparation Example 1 in that the inorganic filler is alumina powder with a particle size of 45±5μm and aluminum powder with a particle size of 15±5μm, with a mass ratio of alumina powder to aluminum powder of 1:1.

[0032] Preparation Example 4 A heat-resistant coating differs from Preparation Example 1 in that the inorganic filler is aluminum powder with a particle size of 18 kg and a particle size of 15 ± 5 μm.

[0033] Preparation Example 5 A heat-resistant coating differs from Preparation Example 1 in that the inorganic filler is prepared using the following method: After cleaning the surface of aluminum powder with alkaline solution, it is mixed with alumina and water at a mass ratio of 1:1:0.2, dried and granulated to obtain dried material. The dried material was heated to 300℃, dehydrated to constant weight, and then ball-milled and sieved to obtain inorganic filler.

[0034] Preparation Example 6 A heat-resistant coating differs from Preparation Example 1 in that the inorganic filler is prepared using the following method: Aluminum powder was added to aluminum hydroxide gel with a water content of 24.3 wt%, and the mass ratio of aluminum powder to aluminum hydroxide was 50:76.5. The mixture was thoroughly mixed, dried, and granulated to obtain a dried material. The dried material was heated to 300℃, dehydrated to constant weight, and then ball-milled and sieved to obtain inorganic filler.

[0035] Preparation Example 7 A heat-resistant coating differs from Preparation Example 1 in that the raw materials also include 5.2~6.4 kg of octenyl succinic acid starch.

[0036] The preparation method of heat-resistant coating is as follows: Mix alkali and water at a ratio of 1:12 to form an alkali solution. Polysiloxane, tetraethyl orthosilicate, ethanol, alkali, remaining water, and inorganic filler are mixed evenly and stirred continuously until the material viscosity reaches 6000 cps. Then, alkali solution is added and mixed evenly. Finally, octenyl succinic acid starch is added and stirred evenly to obtain a heat-resistant coating.

[0037] Preparation Example 8 A heat-resistant coating differs from Preparation Example 1 in that the aluminum powder particle size in the inorganic filler is 2±1μm.

[0038] Preparation Example 9 A heat-resistant coating, which differs from Preparation Example 1 in that the particle size of the inorganic filler is 30±5μm.

[0039] Preparation Example 10 A heat-resistant coating, which differs from Preparation Example 1 in that the particle size of the inorganic filler is 80±5μm.

[0040] Blank preparation example 1 A heat-resistant coating, which differs from Preparation Example 1 in that the amount of inorganic filler is 0.

[0041] Example 1 As attached Figure 1 As shown, a heat-resistant paper bowl includes a paper body 1 with an open top.

[0042] As attached Figure 1 and attached Figure 2 As shown, a heat-resistant layer 2, formed by curing a heat-resistant coating, is attached to the side and bottom surfaces of the main body 1. The thickness of the heat-resistant layer 2 is 0.4 mm. The heat-resistant coating used in this embodiment is the heat-resistant coating of Preparation Example 1.

[0043] Meanwhile, the heat-resistant layer on the side of the main body is also covered with a coating film 3. The coating film 3 is an organic material, such as polypropylene, with a thickness of 0.05mm. This adjusts the tactile feel of the paper bowl's side and prevents the side from getting oil stains that affect its appearance.

[0044] Examples 2-10 A heat-resistant paper bowl differs from Example 1 in that it uses a different heat-resistant coating, as detailed in the table below.

[0045] Table 1. Sources of heat-resistant coatings used in Examples 2-10 Example 2 Preparation Example 2 Example 3 Preparation Example 3 Example 4 Preparation Example 4 Example 5 Preparation Example 5 Example 6 Preparation Example 6 Example 7 Preparation Example 7 Example 8 Preparation Example 8 Example 9 Preparation Example 9 Example 10 Preparation Example 10

[0046] A paper bowl that differs from Example 1 in that it consists only of the main body.

[0047] Blank example 2 A paper bowl, which differs from Example 1 in that the heat-resistant coating used is the blank preparation example 1.

[0048] Detection Examples 1-10 and the preparation examples of the corresponding coatings were tested. The tests included heat resistance test of the paper bowl, electromagnetic heating test of the paper bowl, and adhesion test of the heat-resistant coating.

[0049] Paper bowl heat resistance test: A circular thermocouple is used as the heat source. The bottom of an empty paper bowl is placed on the thermocouple for heating. The heating temperature starts at 180℃, and each stage is 10℃. If the paper bowl does not char, deform, or ignite within 30 minutes of each stage, it is considered to have passed the current heating temperature stage. The next stage test is conducted with a new sample and a new heating temperature. Deformation of the paper bowl (excluding the coating film) is the observation object. The test continues until the paper bowl chars, deforms, or ignites within 30 minutes of each stage. The previous stage test result is then taken as the heat resistance test result, and the heating temperature of the previous stage is recorded as the heat resistance temperature.

[0050] Paper bowl contact heating speed test: Add water to the paper bowl to half its volume and place it on an electric heating heater with a heating temperature of 220℃. Measure the heating time required for the water temperature in the paper bowl to rise to 80℃.

[0051] Paper bowl electromagnetic heating test: Add water to the paper bowl to half its volume, place it in the center of the heating zone of a 1200W, 220V induction cooker, turn on the induction cooker, and test the heating time required for the water temperature in the paper bowl to rise to 80℃.

[0052] Heat-resistant layer scratch test: The heat-resistant coating is applied to a 1.5mm thick, flat coated paper. After drying, a 0.4mm coating is obtained. The adhesion strength of the heat-resistant coating is tested using the cross-cut test method. The results are recorded as scratch damage grades 0-5, with grade 0 being the best and grade 5 being the worst. The scratch damage grade evaluation criteria correspond to the 0-5 coating damage conditions in the cross-cut test method of GB9286 for paint films. Grade 0 corresponds to grade 0, grade 1 corresponds to grade 1, and so on.

[0053] The test results are as follows: Table 2. Results of heat resistance test and electromagnetic heating test for Examples 1-10 and Blank Example 1

[0054] In the electromagnetic heating test, "*" indicates that the temperature is constantly rising, and electromagnetic heating is not feasible.

[0055] Table 3. Scratch resistance test results of preparation examples 1-10 and blank preparation example 1

[0056] As can be seen from Tables 2 and 3, the heat resistance temperature of the paper bowls in Examples 1-10 is significantly higher than that of blank Example 1. Based on the commonalities of Examples 1-10, it can be seen that this application prepares the heat-resistant coating of Examples 1-10 by coating the bottom and outer surface of the paper bowl and curing it to form a heat-resistant layer, which can effectively improve the stability of the paper bowl during the heating process.

[0057] Comparing Examples 1-2 with Blank Example 1, it can be seen that Example 1 can be heated under electromagnetic eddy current, while Example 2 and Blank Example 1 cannot. The heat-resistant layer cured by the heat-resistant coating containing aluminum powder can enable the paper bowl to be heated by electromagnetic force.

[0058] Comparing Examples 1-2 with Blank Example 2, and comparing Preparation Examples 1-2 with Blank Preparation Example 1, it can be seen that the inorganic filler has free hydroxyl groups on its surface, which have good compatibility with polysiloxane. When mixed into the coating, it enhances the adhesion of the coating to the paper surface, making the coating easier to apply. Furthermore, the appropriate proportion of inorganic filler fills the cured polysiloxane, reducing the porosity in the cured coating, thereby improving the thermal conductivity of the cured polysiloxane. This allows the coating to have both heat resistance and suitable thermal conductivity, enabling the paper cup to be heated by a heat source.

[0059] Comparing Examples 1 and 3-6, it can be seen that the composition of inorganic fillers, the structure of powder, and the overall density of powder structure during the preparation process affect the heat resistance temperature of the heat-resistant layer on the paper cup, and also affect the scratch resistance of the heat-resistant layer.

[0060] For Examples 3-4, only aluminum powder is used as an inorganic filler. The bonding strength between the aluminum powder surface and the cured polysiloxane is relatively weak, and the edges of the aluminum powder surface are sharp. When dragged, it is easy to further scratch the heat-resistant layer, resulting in poor scratch resistance of the heat-resistant layer.

[0061] The inorganic filler obtained by directly mixing alumina and aluminum powder, then drying and ball milling, has pores easily trapped between the alumina and aluminum powder particles, making the particles prone to breakage. Therefore, when the heat-resistant layer is scratched or squeezed, the scratch resistance of Example 5 is also worse than that of Example 1.

[0062] Inorganic fillers prepared by simply mixing aluminum powder with aluminum hydroxide gel and then processing it still have gaps between the aluminum powder and aluminum hydroxide bonding surfaces in the powder particles. Only by mixing aluminum powder that has been alkali-washed with a non-dense aluminum hydroxide gel, and then gradually densifying and dehydrating it to tightly coat the aluminum powder, creating a sharp edge coating, and improving the bonding strength between the inorganic filler and the cured polysiloxane, thereby enhancing the scratch resistance of the heat-resistant layer. Therefore, the scratch resistance of Example 1 is better than that of Examples 3-6.

[0063] In addition, the addition of alumina to the inorganic filler has a synergistic effect on improving the heat resistance temperature of paper bowls.

[0064] Comparing Examples 1 and 7, it can be seen that adding octenyl succinic acid starch to the heat-resistant coating can improve the film-forming properties of the heat-resistant coating. When the paper bowl is overheated during heating, the carbonization volume expands and forms heat-insulating voids, which prevent the heat source from continuing to heat the paper bowl and provide a safety protection function. Therefore, Example 7 is superior to Example 1 in terms of heat resistance stability, and the scratch resistance of the coating prepared in Example 7 is superior to that prepared in Example 1.

[0065] The particle size of aluminum powder affects the coating of aluminum powder by alumina in inorganic filler powder, and the overall particle size variation of inorganic filler affects the dispersion of inorganic filler in heat-resistant coating and even the cured heat-resistant layer. Comparing Examples 1 and Examples 8-10, it can be seen that the heat resistance temperature of Example 1 is better than that of Examples 8-10, and the scratch resistance of Example 1 is better than that of Examples 8-10. Therefore, in this application, the particle size of inorganic filler is preferably 40-50 μm, and the particle size of aluminum powder is preferably 10-20 μm.

[0066] Preparation Example 11 A heat-resistant coating, differing from that of Preparation Example 7, contains: 100 kg of polysiloxane, 34 kg of tetraethyl orthosilicate, 14 kg of ethanol, 0.5 kg of alkali, 23 kg of water, 30 kg of inorganic filler, and 5.2 kg of octenyl succinic acid starch.

[0067] Preparation Example 12 A heat-resistant coating, differing from that of Preparation Example 7, contains: 100 kg of polysiloxane, 42 kg of tetraethyl orthosilicate, 20 kg of ethanol, 0.7 kg of alkali, 32 kg of water, 39 kg of inorganic filler, and 6.4 kg of octenyl succinic acid starch.

[0068] Preparation Example 13 A heat-resistant coating differs from Preparation Example 7 in that the amounts of aluminum powder and aluminum hydroxide gel are adjusted, and aluminum powder accounts for 40 wt% of the inorganic filler.

[0069] Preparation Example 14 A heat-resistant coating differs from Preparation Example 7 in that the amounts of aluminum powder and aluminum hydroxide gel are adjusted, and aluminum powder accounts for 55 wt% of the inorganic filler.

[0070] Example 11 A heat-resistant paper bowl, which differs from Example 1 in that the heat-resistant coating used is the same as that used in Preparation Example 11.

[0071] Example 12 A heat-resistant paper bowl, which differs from Example 1 in that the heat-resistant coating used is the same as that used in Preparation Example 12.

[0072] Example 13 A heat-resistant paper bowl, which differs from Example 1 in that the heat-resistant coating used is the same as that used in Preparation Example 13.

[0073] Example 14 A heat-resistant paper bowl, which differs from Example 1 in that the heat-resistant coating used is the same as that used in Preparation Example 14.

[0074] The paper bowls of Examples 11-14 and the coatings prepared in Preparation Examples 11-14 were tested, and the test results are as follows.

[0075] Table 4. Results of heat resistance test and electromagnetic heating test for Examples 11-14

[0076] Table 5. Results of heat resistance test and electromagnetic heating test for preparation examples 11-14

[0077] As shown in Tables 2-4, by comparing the blank example, Example 1, Example 7, and Examples 11-14, the mass ratio of raw materials used in the heat-resistant coating on the paper bowl can be: polysiloxane: tetraethyl orthosilicate: ethanol: alkali: water: inorganic filler: octenyl succinic acid starch = 100: (34-42): (14-20): (0.5-0.7): (23-32): (30-39): (5.2-6.4). Within this range, superior heat resistance and scratch resistance are achieved, ensuring that the paper bowl can maintain structural stability under heating, and the coating is not easily damaged by scratches, thus affecting the product's appearance and coating effect.

[0078] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of protection claimed by the present invention, they are protected by patent law.

Claims

1. A heat resistant paper bowl characterized by: The device includes a body (1) with an opening at the top and a heat-resistant layer (2) attached to the outside of the body. The heat-resistant layer (2) is obtained by laminating a heat-resistant coating, which comprises the following raw materials in parts by weight: 100 parts of polysiloxane 40 parts of tetraethyl orthosilicate 17 parts of ethanol Sodium hydroxide 0.6 parts, 28 parts water 36 parts of inorganic filler; The polysiloxane is a linear methoxy polysiloxane with a relative molecular weight of 3000; The inorganic filler is a composite filler, specifically a powder formed by aluminum powder particles coated with alumina, with an overall particle size of 45±5μm, of which the aluminum powder particle size is 15±5μm.

2. The heat-resistant paper bowl according to claim 1, characterized in that, The aluminum powder accounts for 40-55% of the inorganic filler mass, and the alumina accounts for 45-60% of the inorganic filler mass.

3. A heat-resistant paper bowl according to claim 2, characterized in that, The preparation method of the inorganic filler is as follows: The aluminum powder was cleaned with an alkaline solution, then added to aluminum hydroxide gel, mixed thoroughly, dried, and granulated to obtain a dried material. The dried material was heated to 300℃, dehydrated to constant weight, and then ball-milled and sieved to obtain inorganic filler.

4. A heat-resistant paper bowl according to claim 1 or 2, characterized in that, It also includes octenyl succinic starch.

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