A foam gasket suitable for beverages that replaces molded gaskets

Abstract

The present invention relates to the field of gasket technology, and specifically to a foam gasket suitable for beverages that can replace molded gaskets. The foam gasket includes a gasket matrix using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix also include the following percentages: 2-4% strong rib filler, 1.5-3% strong rib complementary material, 0.5-1.5% foaming gas, and 0.3-0.8% nucleating agent; it has a foamed pore structure, and its density is lower than that of traditional materials. The amount of gasket material used for the same volume is small, the loss is low, and the production cost can be reduced; at the same time, the foam gasket does not need to be pressed into shape, which is conducive to maintaining the foaming structure and facilitating the improvement of production efficiency; importantly, the foam gasket can obtain higher material strength through the cooperation of the thermoplastic composite material with the strong rib filler, thereby avoiding the strength reduction phenomenon caused by the foaming structure, and at the same time, the strong rib complementary material can improve the elasticity or toughness of the material while improving the material strength, thereby facilitating the acquisition of a good compression deformation rate, so that it can reduce the sealing torque of the beverage.

Description

Technical Field

[0001] The present invention relates to the technical field of gaskets, in particular to a foam gasket suitable for beverages and capable of replacing a molded gasket. Background Art

[0002] At present, in order to obtain good sealing performance, beverage filling bottles generally have molded gaskets installed inside the bottle caps. After sealing, the molded gaskets are squeezed between the beverage bottle mouth to form a large sealing torque, which requires a large force for consumers to open. If there are defects in the process matching, it is difficult for consumers to unscrew it.

[0003] In addition, existing molding processes present significant technical challenges. These processes utilize equipment capable of extruding granular materials, such as polyethylene and polypropylene, which are then melted and added to a bottle cap mold, where they are then pressed into the desired shape according to the mold's contours. During production, machine productivity is significantly affected by material type, weight, and shape. The extrusion-blanking-compression molding process results in high material density, high material loss, and high unit product weight, resulting in low production efficiency. Therefore, a foam gasket was considered that could reduce production costs and minimize losses. In light of this, we propose a foam gasket suitable for beverages as an alternative to molded gaskets. Summary of the Invention

[0004] In order to make up for the above deficiencies, the present invention provides a foam gasket suitable for beverages that can replace the molded gasket.

[0005] The technical solution of the present invention is:

[0006] A foam gasket suitable for beverages that replaces molded gaskets. The foam gasket includes a gasket matrix using a thermoplastic composite material as a base material. The raw materials for preparing the gasket matrix also include the following percentages: 2-4% strong rib filler, 1.5-3% strong rib complementary material, 0.5-1.5% foaming gas, and 0.3-0.8% nucleating agent.

[0007] Preferably, the mass percentages of the components of the thermoplastic composite material are as follows:

[0008] Polyethylene: 40-50%;

[0009] Polypropylene: 40-50%;

[0010] Styrene-acrylonitrile copolymer: 10-20%.

[0011] It should be noted that polyethylene and polypropylene materials have good flexibility and sealing properties, which can prevent beverages from leaking or oxidizing. However, their main toughness characteristics lead to lower strength, and the addition of fillers will cause the toughness to decrease. Therefore, the amount of filler used is relatively small. Styrene-acrylonitrile copolymer can obtain good strength and toughness, improve the material's compressive and tensile strength, and has corrosion resistance. It can be used in beverages containing acetic acid, malic acid, and carbonated beverages. At the same time, this material is conducive to cooperating with gas to form a pore structure, and the pore-forming effect is better.

[0012] Preferably, the reinforcing filler is any one or more of silicate, calcium carbonate, alumina, activated silica, talc, and perlite. This filler can improve the material's high-temperature resistance, enabling the filling of high-temperature beverages. Importantly, the foamed material increases in volume, meaning its unit volume density decreases, which reduces its strength. This requires the addition of reinforcing fillers to enhance strength. However, the addition of such fillers, while increasing strength, also reduces the material's toughness.

[0013] Preferably, the reinforcing complementary material is any one or more of polyamide, nitrocellulose, and hydroxypropyl methylcellulose; the main purpose of the reinforcing complementary material is to cooperate with the reinforcing filler to further improve its reduced toughness and maintain good material toughness or elasticity. At the same time, the material can also promote strength improvement.

[0014] Preferably, the foaming gas is food-grade carbon dioxide, or any one or more of the inert gases nitrogen and helium. No chemical foaming agents are used in this process, and gas foaming can avoid chemical residues caused by foaming agents, making it suitable for beverages. At the same time, the physical gas does not affect the mechanical properties of the gasket, maintaining its durability.

[0015] Preferably, the nucleating agent is ethyl benzoate. It is worth noting that the role of the nucleating agent is to promote the formation of crystal nuclei in thermoplastic composite materials and promote the growth of crystal nuclei, thereby improving the crystallinity and physical and mechanical properties of the material, which is conducive to improving molding efficiency.

[0016] Preferably, an outer surface of the gasket substrate can be provided with an outer layer, and the outer layer material is any one or more of aluminum, tin, polypropylene, polyethylene, and polyester.

[0017] Preferably, the preparation method of the gasket matrix is: adding thermoplastic composite material to the extruder and mixing it with hot melt, then adding other prepared raw materials into the hot melt mixture in proportion and mixing, extruding it through the extruder outlet, forming a gasket inside the mold, and punching it to form a foam gasket of the required specifications.

[0018] Preferably, the foaming gas is injected during the mixing process of the hot melt mixture, and the gas pressure is controlled to be 2-6 MPa and the gas injection rate is controlled to be 10-30 ml / min.

[0019] Preferably, the punching process adopts a flat plate punching method, and the punching pressure is controlled to be 300-500 kN and the punching speed is 30-60 strokes / min.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The foam gasket suitable for beverages, which is a substitute for molded gaskets, has a foamed pore structure and a lower density than that of traditional materials. The same volume of gasket material uses less and has low loss, which can reduce production costs. At the same time, the foam gasket does not need to be pressed into shape, which is conducive to maintaining the foam structure and improving production efficiency. More importantly, the foam gasket can obtain higher material strength through the cooperation of thermoplastic composite materials with strong rib fillers, avoiding the strength reduction phenomenon caused by the foam structure. At the same time, the strong rib complementary materials can improve the elasticity or toughness of the material while improving the material strength, so as to obtain a good compression deformation rate and excellent compression rebound performance, and can ensure sealing and provide smaller beverage sealing torque support. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is one of the structural diagrams of the present invention;

[0023] Figure 2 This is the second structural diagram of the present invention;

[0024] Figure 3 This is the third structural diagram of the present invention;

[0025] Figure 4 This is the SEM image of the gasket substrate of Example 1 of the present invention.

[0026] The meaning of each number in the figure is:

[0027] 1. Gasket base; 2. Surface layer. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] See also Figure 1-4 The present invention describes the above technical solution in detail through the following embodiments:

[0030] Example 1

[0031] A foam gasket suitable for beverages that can replace molded gaskets is characterized in that the foam gasket includes a gasket matrix 1 using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix 1 also include the following percentages by mass of the thermoplastic composite material: 2% alumina as a reinforcing filler, 1.5% hydroxypropyl methylcellulose as a reinforcing complementary material, 1% food-grade carbon dioxide as a foaming gas, and 0.5% ethyl benzoate as a nucleating agent.

[0032] The specific mass percentages of the components of the thermoplastic composite material are:

[0033] Polyethylene: 40%;

[0034] Polypropylene: 40%;

[0035] Styrene-acrylonitrile copolymer: 20%.

[0036] The foam gasket of this embodiment adopts Figure 3 The structure shown is provided with only the gasket base 1, wherein Figure 4 This is the SEM image of the gasket substrate of Example 1, which has an obvious foaming structure.

[0037] The preparation method of the foam gasket of this embodiment is as follows: adding a thermoplastic composite material to a single-screw extruder, heating, mixing and hot melting, controlling the temperature of the feeding zone to 160°C, the barrel zone to 190°C, and the screw speed to 200r / min, and adding other prepared raw materials in proportion to the feeding zone and mixing. The foaming gas, food-grade carbon dioxide, is injected during the mixing process, and the gas pressure is controlled to 4MPa and the gas injection rate is 20ml / min; extruding through the extruder outlet, controlling the die head temperature to 190°C and the die mouth temperature to 200°C, injecting into the mold to form a gasket, and punching to form a foam gasket with a diameter of 20±0.1mm and a thickness of 1mm.

[0038] Example 2

[0039] A foam gasket suitable for beverages that can replace molded gaskets is characterized in that the foam gasket includes a gasket matrix 1 using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix 1 also include the following percentages by mass of the thermoplastic composite material: 2% alumina as a reinforcing filler, 1.5% hydroxypropyl methylcellulose as a reinforcing complementary material, 1.5% food-grade carbon dioxide as a foaming gas, and 0.5% ethyl benzoate as a nucleating agent.

[0040] The specific mass percentages of the components of the thermoplastic composite material are:

[0041] Polyethylene: 40%;

[0042] Polypropylene: 40%;

[0043] Styrene-acrylonitrile copolymer: 20%.

[0044] The foam gasket of this embodiment adopts Figure 3 The structure shown is provided with only the gasket base 1, wherein Figure 4 This is the SEM image of the gasket substrate of Example 1, which has an obvious foaming structure.

[0045] The preparation method of the foam gasket of this embodiment is as follows: adding a thermoplastic composite material to a single-screw extruder, heating, mixing and hot melting, controlling the temperature of the feeding zone to 160°C, the barrel zone to 190°C, and the screw speed to 200r / min, and adding other prepared raw materials in proportion to the feeding zone and mixing, injecting foaming gas food-grade carbon dioxide during the mixing process, controlling the gas pressure to 4MPa, and the gas injection rate to 20ml / min; extruding through the extruder outlet, controlling the die head temperature to 190°C and the die mouth temperature to 200°C, injecting into the mold to form a gasket, and punching to form a foam gasket with a diameter of 20±0.1mm and a thickness of 1mm.

[0046] Example 3

[0047] A foam gasket suitable for beverages that can replace molded gaskets is characterized in that the foam gasket includes a gasket matrix 1 using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix 1 also include the following percentages by mass of the thermoplastic composite material: 2% alumina as a reinforcing filler, 1.5% hydroxypropyl methylcellulose as a reinforcing complementary material, 1% food-grade carbon dioxide as a foaming gas, and 0.5% ethyl benzoate as a nucleating agent.

[0048] The specific mass percentages of the components of the thermoplastic composite material are:

[0049] Polyethylene: 45%;

[0050] Polypropylene: 45%;

[0051] Styrene-acrylonitrile copolymer: 10%.

[0052] The foam gasket of this embodiment adopts Figure 3 The structure shown is provided with only the gasket base 1, wherein Figure 4 This is the SEM image of the gasket substrate of Example 1, which has an obvious foaming structure.

[0053] The preparation method of the foam gasket of this embodiment is as follows: adding a thermoplastic composite material to a single-screw extruder, heating, mixing and hot melting, controlling the temperature of the feeding zone to 160°C, the barrel zone to 190°C, and the screw speed to 200r / min, and adding other prepared raw materials in proportion to the feeding zone and mixing. The foaming gas, food-grade carbon dioxide, is injected during the mixing process, and the gas pressure is controlled to 4MPa and the gas injection rate is 20ml / min; extruding through the extruder outlet, controlling the die head temperature to 190°C and the die mouth temperature to 200°C, injecting into the mold to form a gasket, and punching to form a foam gasket with a diameter of 20±0.1mm and a thickness of 1mm.

[0054] Example 4

[0055] A foam gasket suitable for beverages that can replace molded gaskets is characterized in that the foam gasket includes a gasket matrix 1 using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix 1 also include the following percentages by mass of the thermoplastic composite material: 4% alumina as a reinforcing filler, 1.5% hydroxypropyl methylcellulose as a reinforcing complementary material, 1% food-grade carbon dioxide as a foaming gas, and 0.5% ethyl benzoate as a nucleating agent.

[0056] The specific mass percentages of the components of the thermoplastic composite material are:

[0057] Polyethylene: 40%;

[0058] Polypropylene: 40%;

[0059] Styrene-acrylonitrile copolymer: 20%.

[0060] The foam gasket of this embodiment adopts Figure 3 The structure shown is provided with only the gasket base 1, wherein Figure 4 This is the SEM image of the gasket substrate of Example 1, which has an obvious foaming structure.

[0061] The preparation method of the foam gasket of this embodiment is as follows: adding a thermoplastic composite material to a single-screw extruder, heating, mixing and hot melting, controlling the temperature of the feeding zone to 160°C, the barrel zone to 190°C, and the screw speed to 200r / min, and adding other prepared raw materials in proportion to the feeding zone and mixing. The foaming gas, food-grade carbon dioxide, is injected during the mixing process, and the gas pressure is controlled to 4MPa and the gas injection rate is 20ml / min; extruding through the extruder outlet, controlling the die head temperature to 190°C and the die mouth temperature to 200°C, injecting into the mold to form a gasket, and punching to form a foam gasket with a diameter of 20±0.1mm and a thickness of 1mm.

[0062] Example 5

[0063] A foam gasket suitable for beverages that can replace molded gaskets is characterized in that the foam gasket includes a gasket matrix 1 using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix 1 also include the following percentages by mass of the thermoplastic composite material: 2% alumina as a reinforcing filler, 3% hydroxypropyl methylcellulose as a reinforcing complementary material, 1% food-grade carbon dioxide as a foaming gas, and 0.5% ethyl benzoate as a nucleating agent.

[0064] The specific mass percentages of the components of the thermoplastic composite material are:

[0065] Polyethylene: 40%;

[0066] Polypropylene: 40%;

[0067] Styrene-acrylonitrile copolymer: 20%.

[0068] The foam gasket of this embodiment adopts Figure 3 The structure shown is provided with only the gasket base 1, wherein Figure 4 This is the SEM image of the gasket substrate of Example 1, which has an obvious foaming structure.

[0069] The preparation method of the foam gasket of this embodiment is as follows: adding a thermoplastic composite material to a single-screw extruder, heating, mixing and hot melting, controlling the temperature of the feeding zone to 160°C, the barrel zone to 190°C, and the screw speed to 200r / min, and adding other prepared raw materials in proportion to the feeding zone and mixing. The foaming gas, food-grade carbon dioxide, is injected during the mixing process, and the gas pressure is controlled to 4MPa and the gas injection rate is 20ml / min; extruding through the extruder outlet, controlling the die head temperature to 190°C and the die mouth temperature to 200°C, injecting into the mold to form a gasket, and punching to form a foam gasket with a diameter of 20±0.1mm and a thickness of 1mm.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 1 is that the reinforcing filler alumina is not added in this comparative example, and other conditions are the same.

[0072] Comparative Example 2

[0073] The difference between this comparative example 2 and Example 1 is that the gluten-strengthening complementary material hydroxypropyl methylcellulose is not added in this comparative example, and other conditions are the same.

[0074] Comparative Example 3

[0075] The difference between Comparative Example 3 and Example 1 is that food-grade carbon dioxide, a foaming gas, is not added in this comparative example, and other conditions are the same.

[0076] According to Examples 1-5 and Comparative Examples 1-3, corresponding foam gaskets were prepared as samples, and their compression residual strain and compression deformation rate were tested to determine their elasticity, sealing properties, and torque. The specific steps were as follows: each sample was placed between the parallel clamps of a compression tester, and when the load was applied to 9.8 N, the actual gasket height T0 was measured; the compression speed was controlled at 5 mm / min, and then the load was applied to 1176 N, maintained for 1 minute, and the compression test gasket height T1 was recorded; the load was then removed at a rate of 5 mm / min until the load reached 9.8 N, and the gasket height T2 was recorded:

[0077] The compression deformation rate (%) is calculated according to the formula:

[0078]

[0079] The compressive residual strain (%) is calculated according to the formula:

[0080]

[0081] Where: A is the compression deformation rate (%); B is the compression residual strain (%); T0 is the actual gasket height (mm); T1 is the gasket height after compression (mm); T2 is the gasket height after unloading (mm).

[0082] The specific data are as follows:

[0083] Compression deformation rate (%) Compressive residual strain (%) Example 1 52.3 12.1 Example 2 56.1 10.3 Example 3 49.5 13.7 Example 4 47.1 14.9 Example 5 53.5 9.8 Comparative Example 1 64.2 30.9 Comparative Example 2 33.7 24.7 Comparative Example 3 22.3 27.9

[0084] The data in the table above show that adding an appropriate amount of food-grade carbon dioxide as the foaming gas can increase the compression set rate and maintain good resilience, with a slightly reduced compression residual strain. Without adding the foaming gas, the compression set rate will be greatly reduced, and the compression residual strain will increase, that is, the elasticity will be reduced, which is not conducive to obtaining good sealing and small torque.

[0085] A decrease in the content of styrene-acrylonitrile copolymer and an increase in the content of aluminum oxide as a reinforcing filler in thermoplastic composite materials will both result in a decrease in the compression deformation rate and an increase in the compression residual strain, that is, a decrease in resilience; styrene-acrylonitrile copolymer can enhance toughness and improve elasticity, while aluminum oxide as a reinforcing filler will increase strength, resulting in a decrease in toughness, which in turn leads to a decrease in resilience, affecting sealing and torque; and an increase in hydroxypropyl methylcellulose as a reinforcing filler can improve resilience, result in a higher compression deformation rate, and provide better sealing.

[0086] Moreover, if the reinforcing filler alumina is not added, although a higher compression deformation rate can be obtained, the insufficient mechanical strength of the material will greatly reduce the rebound resilience and cause a higher compressive residual strain.

[0087] In summary, embodiment 2 or embodiment 5 may be preferred.

[0088] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A foam gasket suitable for beverages that replaces molded gaskets, characterized by: The foamed gasket comprises a gasket matrix (1) using a thermoplastic composite material as a base material, and the raw materials for preparing the gasket matrix (1) further comprise the following percentages of the thermoplastic composite material: 2-4% reinforcing filler, 1.5-3% reinforcing complementary material, 0.5-1.5% foaming gas, and 0.3-0.8% nucleating agent; The reinforcing filler is alumina, and the reinforcing complementary material is hydroxypropyl methylcellulose; The mass percentages of the components of the thermoplastic composite material are specifically as follows: Polyethylene (PE): 40-50%; Polypropylene: 40-50%; Styrene-acrylonitrile copolymer: 10-20%.

2. The foam gasket suitable for beverages as a substitute for molded gaskets according to claim 1, characterized in that: The foaming gas is any one or more of food-grade carbon dioxide, inert gas nitrogen, and helium.

3. The foam gasket suitable for beverages as a substitute for molded gaskets according to claim 1, characterized in that: The nucleating agent is ethyl benzoate.

4. The foam gasket suitable for beverages as a substitute for molded gaskets according to claim 1, characterized in that: The outer surface of the gasket base (1) is provided with an outer layer (2), and the material of the outer layer (2) is any one or more of aluminum, tin, polypropylene, polyethylene, and polyester.

5. The foam gasket suitable for beverages as a substitute for molded gaskets according to claim 1, characterized in that: The preparation method of the gasket matrix (1) is as follows: adding a thermoplastic composite material to an extruder for hot melting, then adding other raw materials to the hot melt mixture in proportion and mixing, extruding through the extruder outlet, forming a gasket inside a mold, and punching to form a foam gasket of required specifications.

6. The foam gasket suitable for beverages as a substitute for molded gaskets according to claim 1, characterized in that: The foaming gas is injected during the mixing process of the hot melt mixture, and the gas pressure is controlled to be 2-6 MPa and the gas injection rate is 10-30 ml / min.

7. The foam gasket suitable for beverages as a substitute for molded gaskets according to claim 1, characterized in that: The punching process adopts a flat plate punching method, and the punching pressure is controlled to be 300-500 kN and the punching speed is 30-60 strokes / min.

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