Metal-detectable earplug and preparation method therefor

Abstract

The present invention provides a metal-detectable earplug and a preparation method therefor. The metal-detectable earplug comprises an earplug body primarily composed of polyurethane or thermoplastic rubber. Metal powder accounting for 0.5%-15% of the weight of the earplug body is uniformly distributed in the earplug body. By uniformly distributing the metal powder in the polyurethane or TPR, the metal-detectable earplug of the present invention can be detected by a metal detector without compromising the sound isolation efficacy and wearing comfort of the earplug.

Description

Metal detectable earplug and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of earplugs, and in particular to a metal detectable earplug and a preparation method thereof. Background Art

[0002] In production workshops, machines generate noise exceeding 85dB. Prolonged exposure to such noise can lead to hearing loss. Therefore, workers are required to wear earplugs for hearing protection. However, earplugs are small and soft, easily deforming and falling out of the ear canal. In some specialized industries, such as those producing or processing food, beverages, and pharmaceuticals, there's a risk of earplugs falling into the product, causing foreign matter contamination. To address this risk, these specialized industries incorporate metal components such as metal rods, metal springs, and metal wire into the earplugs. Metal detectors are used to detect dropped earplugs to prevent foreign matter contamination.

[0003] For example, the Chinese appearance patent with authorization number CN305940606S discloses an earplug (metal detectable TPR). From the appearance diagram disclosed in the patent, it can be seen that a metal rod is provided inside the earplug, and a metal detector can detect the earplug by detecting the metal rod.

[0004] For example, Chinese utility model patent with authorization number CN212416078U discloses a metal detectable TPR rubber earplug, in which a spring is provided inside the earplug body, and a metal detector can detect the earplug by detecting the spring.

[0005] However, embedding metal components such as metal rods and metal springs into the earplug increases its weight and hardness, making it uncomfortable to wear. To address this issue, Chinese utility model patent number CN214434795U discloses an earplug with a metal-detectable earplug cable. The cable comprises a connecting cable and earplug bodies at both ends of the connecting cable. The connecting cable comprises a metal wire and a plastic coating wrapped around the outer periphery of the metal wire, with both ends of the connecting cable inserted into the earplug body. This technical solution achieves a metal-detectable function by embedding a metal wire into the connecting cable of the earplug, effectively solving the problem of wearing discomfort caused by embedding detectable metal components into the earplug body.

[0006] However, the metal components such as metal rods, metal springs, and metal wires built into the earplug body increase the production process of inserting metal into the earplug, which reduces production efficiency and increases production costs.

[0007] Furthermore, common metals such as iron, copper, and aluminum generally conduct sound very well. The speed of sound in iron is 5200 m / s, in copper it is 3750 m / s, and in aluminum it is 5000 m / s. By comparison, the speed of sound in air is 340 m / s. The purpose of wearing earplugs is to reduce or block noise and protect the ears. However, the addition of metal components to earplugs increases the speed at which sound enters the ears, effectively reducing the sound insulation effect.

[0008] Therefore, it is urgent to develop a new metal detectable earplug to solve the defects of "increasing the weight and hardness of the earplug, making it uncomfortable to wear" and "reducing the sound insulation effect" caused by the built-in metal parts in the earplug.

[0009] Summary of the Invention

[0010] In order to overcome the shortcomings of the existing technology, the present invention provides a metal detectable earplug and a preparation method thereof, which solves the defects of the existing technology of "increasing the weight and hardness of the earplug, making it uncomfortable to wear" and "reducing the sound insulation effect" caused by building metal parts into the earplug.

[0011] The technical solution of the present invention is as follows: a metal detectable earplug, comprising an earplug body whose main component is polyurethane or TPR, wherein metal powder accounting for 0.5-15% of the weight of the earplug body is evenly distributed in the earplug body.

[0012] The metal powder is iron, copper, aluminum or a mixture thereof, and the particle size of the metal powder is 0.5um-350um.

[0013] The components contained in the metal detectable earplug and the content of each component are as follows: component A: 100 parts of isocyanate prepolymer; component B: 75-85 parts of water-based acrylate prepolymer, 3-7 parts of porosizing agent, 1-2 parts of softener, 2-30 parts of metal powder, and 9-10 parts of auxiliary agent; wherein the usage ratio of component A to component B is 1:1.

[0014] The auxiliary agent includes: 3-7 parts of surface stabilizer, 1-2 parts of coagulant, 1-2 parts of color powder, and 1-2 parts of temperature-sensing agent.

[0015] The preparation method of the metal detectable earplug is as follows: 1) measuring component B and component A respectively; 2) adding component A to material tank one and heating to 40° C.; 3) adding component B to material tank two, mixing evenly, and cooling to 8-12° C.; 4) extruding the materials in material tanks one and two into an injection molding machine, stirring at a speed of 5000 rpm for 10 minutes to carry out a foaming reaction, and extruding into a mold and injection molding to obtain the metal detectable earplug.

[0016] The components and content of the metal detectable earplug are as follows: 30-55% of polyether polyol, 25-30% of polyester polyol, 10-20% of isocyanate, 0.5-15% of metal powder, 0.5-1% of water, 1-2% of silicone oil, and 7.5-14% of additives.

[0017] The auxiliary agent comprises: 1.5-12% of a surface stabilizer, 0.5-2% of a coagulant, 0.5-2% of a color powder, and 1-2% of a temperature-sensing agent.

[0018] The preparation method of the metal detectable earplug is as follows: weigh the materials, add them into a material tank machine, mix them evenly, extrude them into an injection molding machine, stir them at a speed of 5000 rpm for 10 minutes, carry out foaming reaction, extrude them into a mold, and injection mold them to obtain the metal detectable earplug.

[0019] The components and content of the metal detectable earplug are as follows: 85-93% of thermoplastic rubber (TPR), 1-3% of metal powder, 1-2% of silicone oil, and 5-10% of auxiliary agent.

[0020] The auxiliary agent comprises: 3-8% of surface stabilizer, 0.5-2% of coagulant, 0.5-1% of color powder and 1-2% of temperature sensitive agent.

[0021] The preparation method of the metal detectable earplug is as follows: weighing various materials, adding them into a kneader, crushing and melting them, injecting them into an injection molding machine and extruding them into a mold, and injection molding them to obtain the metal detectable earplug.

[0022] The surface stabilizer is selected from magnesium stearate, aluminum stearate, potassium stearate, etc. The coagulant is ethylenediaminetetraacetic acid, and the temperature-sensitive agent is a temperature-sensitive color-changing powder.

[0023] The metal detectable earplugs described herein are made by reacting an isocyanate prepolymer with a water-based acrylate prepolymer to produce polyurethane; polyether polyols and polyester polyols also react with isocyanates to produce polyurethane. This invention evenly distributes trace amounts of metal powder within polyurethane or TPR molecules, separating the metal powders from each other and preventing them from effectively conducting sound. This addresses the prior art issue of metal components in earplugs, which, due to the metal components' sound-conducting properties, can reduce the earplug's sound insulation or isolation.

[0024] At the same time, the metal detector uses the principle of electromagnetic induction, using a coil with alternating current passing through it to generate a magnetic field. This magnetic field induces eddy currents on the metal, thereby affecting the changes in the coil's magnetic field, causing the metal detector buzzer to emit a sound. Since the particle size of the metal powder is 0.5um-300um and is evenly distributed in the earplug, even if the metal powder is separated by polyurethane molecules or TPR molecules, each independent metal powder can independently induce eddy currents and gather together to affect the changes in the coil's magnetic field, causing the metal detector buzzer to emit a sound. Therefore, detection by the metal detector can be achieved.

[0025] Furthermore, because the metal powder is evenly distributed in the earplug, even if an earplug dropped on the production line is cut into small pieces, it can still be detected by metal detectors. However, if the earplug with metal components is cut away, the part without metal components cannot be detected.

[0026] The metal powder described in this application is added together with other raw materials during the earplug production process without adding additional steps, thereby improving production efficiency and reducing production costs.

[0027] Because metal powder accounts for only 0.5-15% of the total earplug mass, its content is relatively low and evenly distributed throughout the earplug. While the metal powder slightly increases the weight of the earplug, its impact on wearing comfort is negligible. This trace amount of metal powder will not reduce the softness and insulating properties of polyurethane or TPR earplugs.

[0028] The beneficial effects of the present invention are as follows: the metal detectable earplugs of the present invention, by evenly distributing metal powder in polyurethane or TPR, can be detected by a metal detector without reducing the sound insulation effect and wearing comfort of the earplugs. DETAILED DESCRIPTION

[0029] In order to make the purpose of the invention, technical solutions and technical effects of the present invention more clear, the present invention will be further described below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Example 1 A metal detectable earplug includes an earplug body, wherein the earplug body contains 90% by weight of polyurethane and 5% by weight of metal powder, wherein the metal powder is iron and has a particle size of 100 μm.

[0031] Example 2 A metal detectable earplug includes an earplug body, wherein the earplug body contains 85% by weight of polyurethane and 0.5% by weight of metal powder, wherein the metal powder is copper and has a particle size of 350 μm.

[0032] Example 3 A metal detectable earplug includes an earplug body, wherein the earplug body contains 93% by weight of thermoplastic rubber and 15% by weight of metal powder. The metal powder is a mixture of iron, copper, and aluminum, and the particle size of the metal powder is 5 μm.

[0033] Example 4 A metal detectable earplug includes an earplug body, wherein the earplug body contains 90% by weight of thermoplastic rubber and 2% by weight of metal powder, wherein the metal powder is iron and has a particle size of 150 μm.

[0034] Example 5 A metal detectable earplug includes an earplug body, wherein the earplug body contains 70% by weight of thermoplastic rubber and 10% by weight of metal powder. The metal powder is a mixture of iron and copper, and the particle size of the metal powder is 12.5 μm to 200 μm.

[0035] Example 6 A metal detectable earplug includes an earplug body, wherein the earplug body contains 80% by weight of thermoplastic rubber and 1% by weight of metal powder, wherein the metal powder is aluminum and has a particle size of 200 μm.

[0036] Example 7: A metal detectable earplug comprising the following components and their respective proportions: Component A: 100 parts isocyanate prepolymer; Component B: 85 parts water-based acrylate prepolymer, 4 parts porous sponge, 1.5 parts softener, 10 parts metal powder, and 9 parts additives; the ratio of Component A to Component B is 1:1. The additives include 4 parts surface stabilizer, 2 parts coagulant, 1 part colorant, and 1 part temperature-sensing agent. The metal powder is a mixture of iron, copper, and aluminum, and has a particle size of 100 μm.

[0037] The preparation method of the metal detectable earplug is as follows: 1) measuring component B and component A respectively; 2) adding component A to material tank one and heating to 40° C.; 3) adding component B to material tank two, mixing evenly, and cooling to 10° C.; 4) extruding the materials in material tanks one and two into an injection molding machine, stirring at a speed of 5000 rpm for 10 minutes to carry out a foaming reaction, and extruding into a mold and injection molding to obtain the metal detectable earplug.

[0038] Example 8: A metal detectable earplug comprising the following components and their respective proportions: Component A: 100 parts isocyanate prepolymer; Component B: 80 parts water-based acrylate prepolymer, 7 parts porous sponge, 2 parts softener, 1 part metal powder, and 10 parts additives; the ratio of Component A to Component B is 1:1. The additives include 3 parts surface stabilizer, 1 part coagulant, 2 parts colorant, and 2 parts temperature-sensing agent. The metal powder is iron, and its particle size is 50 μm.

[0039] The preparation method of the metal detectable earplug is as follows: 1) measuring component B and component A respectively; 2) adding component A to material tank one and heating to 40° C.; 3) adding component B to material tank two, mixing evenly, and cooling to 12° C.; 4) extruding the materials in material tanks one and two into an injection molding machine, stirring at a speed of 5000 rpm for 10 minutes to carry out a foaming reaction, and extruding into a mold and injection molding to obtain the metal detectable earplug.

[0040] Example 9: A metal detectable earplug comprising the following components and their respective proportions: Component A: 100 parts isocyanate prepolymer; Component B: 75 parts water-based acrylate prepolymer, 3 parts porosifier, 1 part softener, 15 parts metal powder, and 9.5 parts additives; the ratio of Component A to Component B being 1:1. The additives include 7 parts surface stabilizer, 1.5 parts coagulant, 1.5 parts colorant, and 1.5 parts temperature-sensing agent. The metal powder is iron, copper, aluminum, or a mixture thereof, and has a particle size of 12.5 μm to 200 μm.

[0041] The preparation method of the metal detectable earplug is as follows: 1) measuring component B and component A respectively; 2) adding component A to material tank one and heating to 40° C.; 3) adding component B to material tank two, mixing evenly, and cooling to 8° C.; 4) extruding the materials in material tanks one and two into an injection molding machine, stirring at a speed of 5000 rpm for 10 minutes to carry out a foaming reaction, and extruding into a mold and injection molding to obtain the metal detectable earplug.

[0042] Example 10: A metal detectable earplug comprising the following components and their respective proportions: 55% polyether polyol, 25% polyester polyol, 10% isocyanate, 0.5% metal powder, 0.5% water, 1% silicone oil, and 7.5% additives. The additives include 1.5% surface stabilizer, 2% coagulant, 2% colorant, and 2% temperature-sensing agent.

[0043] The preparation method of the metal detectable earplug is as follows: weigh the materials, add them into a material tank machine, mix them evenly, extrude them into an injection molding machine, stir them at a speed of 5000 rpm for 10 minutes, carry out foaming reaction, extrude them into a mold, and injection mold them to obtain the metal detectable earplug.

[0044] Example 11: A metal detectable earplug comprising the following components and their respective proportions: 30% polyether polyol, 30% polyester polyol, 20% isocyanate, 6% metal powder, 1% water, 2% silicone oil, and 14% additives. The additives include 12% surface stabilizer, 0.5% coagulant, 0.5% colorant, and 1% temperature-sensing agent.

[0045] The preparation method of the metal detectable earplug is as follows: weigh the materials, add them into a material tank machine, mix them evenly, extrude them into an injection molding machine, stir them at a speed of 5000 rpm for 10 minutes, carry out foaming reaction, extrude them into a mold, and injection mold them to obtain the metal detectable earplug.

[0046] Example 12: A metal detectable earplug comprising the following components and their respective proportions: 45% polyether polyol, 28% polyester polyol, 12% isocyanate, 15% metal powder, 0.8% water, 1.2% silicone oil, and 11% additives. The additives include 7.5% surface stabilizer, 1% coagulant, 1% colorant, and 1.5% temperature-sensing agent.

[0047] The preparation method of the metal detectable earplug is as follows: weigh the materials, add them into a material tank machine, mix them evenly, extrude them into an injection molding machine, stir them at a speed of 5000 rpm for 10 minutes, carry out foaming reaction, extrude them into a mold, and injection mold them to obtain the metal detectable earplug.

[0048] Example 13: A metal detectable earplug, comprising the following components and their respective proportions: 93% thermoplastic rubber (TPR), 0.5% metal powder, 1% silicone oil, and 5% additives. The additives include: 3% surface stabilizer, 0.5% coagulant, 0.5% colorant, and 1% temperature-sensing agent.

[0049] The preparation method of the metal detectable earplug is as follows: weighing various materials, adding them into a kneader, crushing and melting them, injecting them into an injection molding machine, and extruding them into a mold, injection molding, to obtain the metal detectable earplug.

[0050] Example 14: A metal detectable earplug comprising the following components and their respective proportions: 85% thermoplastic rubber (TPR), 6% metal powder, 2% silicone oil, and 10% additives. The additives include 8% surface stabilizer, 0.5% coagulant, 0.5% colorant, and 1% temperature-sensing agent.

[0051] The preparation method of the metal detectable earplug is as follows: weighing various materials, adding them into a kneader, crushing and melting them, injecting them into an injection molding machine, and extruding them into a mold, injection molding, to obtain the metal detectable earplug.

[0052] Example 15: A metal detectable earplug comprising the following components and their respective proportions: 88% thermoplastic rubber (TPR), 15% metal powder, 1.5% silicone oil, and 8.5% additives. The additives include 5% surface stabilizer, 1% coagulant, 0.8% colorant, and 1.7% temperature-sensing agent.

[0053] The preparation method of the metal detectable earplug is as follows: weighing various materials, adding them into a material tank machine, kneading machine, crushing and melting, injecting them into an injection molding machine, and extruding them into a mold, injection molding, to obtain the metal detectable earplug.

[0054] To further verify the effectiveness of the metal-detectable earplugs described herein, the applicant prepared Comparative Examples 1-15, corresponding to Examples 1-15 above. Each Comparative Example differs from the Examples in that it contains no metal powder. Other components and preparation methods were identical. Each Example and Comparative Example was tested using a commercially available metal detector. The earplugs prepared in each Example were also cut into 1-cubic-centimeter pieces and tested using a metal detector.

[0055] In addition, each earplug was flattened and its rebound speed was recorded with a timer. Each earplug was measured three times and the average value was taken.

[0056] The sound attenuation of the earplugs obtained in each comparative example and each embodiment was measured according to GB5893.3-86 "Subjective Measurement Method for Ear Protectors," where background noise was measured using Method A in GB5893.3-86. The results are shown in the following table.

[0057] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, its architecture can be flexible and varied, and a series of products can be derived. Simply making a few simple deductions or substitutions should be considered to fall within the scope of patent protection of the present invention as determined by the submitted claims.

Claims

1. A metal detectable earplug, characterized in that: The earplug body comprises an earplug body whose main component is polyurethane or thermoplastic rubber, wherein metal powder accounting for 0.5-15% of the weight of the earplug body is evenly distributed in the earplug body.

2. The metal detectable earplug according to claim 1, characterized in that: The metal powder is iron, copper, aluminum, manganese, nickel, chromium, superconductive carbon black or a mixture thereof, and the particle size of the metal powder is 2um-350um.

3. The metal detectable earplug according to claim 1 or 2, characterized in that: The components and the content of each component are as follows: component A: 100 parts of isocyanate prepolymer; component B: 75-85 parts of water-based acrylic prepolymer, 3-7 parts of porous agent, 1-2 parts of softener, 1-30 parts of metal powder, and 9-10 parts of auxiliary agent; the usage ratio of component A to component B is 1:

1.

4. The metal detectable earplug according to claim 3, characterized in that: The auxiliary agent includes: 3-7 parts of surface stabilizer, 1-2 parts of coagulant, 1-2 parts of color powder, and 1-2 parts of temperature-sensing agent.

5. The method for preparing the metal detectable earplug according to claim 3 or 4, characterized in that: The method comprises the following steps: 1) measuring component B and component A respectively; 2) adding component A into a first material tank and heating the mixture to 40° C.; 3) adding component B into a second material tank, mixing the mixture evenly, and cooling the mixture to 8-12° C.; and 4) extruding the materials in the first and second material tanks into an injection molding machine, stirring the materials at a speed of 5000 rpm for 10 minutes to perform a foaming reaction, and extruding the materials into a mold and performing injection molding to obtain the metal detectable earplug.

6. The metal detectable earplug according to claim 1 or 2, characterized in that: The components and content of the metal detectable earplug are as follows: 30-55% of polyether polyol, 25-30% of polyester polyol, 10-20% of isocyanate, 0.5-15% of metal powder, 0.5-1% of water, 1-2% of silicone oil, and 7.5-14% of additives.

7. The metal detectable earplug according to claim 6, characterized in that: The auxiliary agent comprises: 1.5-12% of a surface stabilizer, 0.5-2% of a coagulant, 0.5-2% of a color powder, and 1-2% of a temperature-sensing agent.

8. The method for preparing the metal detectable earplug according to claim 6 or 7, characterized in that: The method comprises the following steps: weighing various materials, adding them into a material tank machine, mixing them evenly, extruding them into an injection molding machine, stirring them at a speed of 5000 rpm for 10 minutes, performing a foaming reaction, and extruding them into a mold, injection molding, and obtaining the metal detectable earplug.

9. The metal detectable earplug according to claim 1 or 2, characterized in that: The components and content of the metal detectable earplug are as follows: 85-93% of thermoplastic rubber (TPR), 0.5-15% of metal powder, 1-2% of silicone oil, and 7-10% of auxiliary agent.

10. The method for preparing the metal detectable earplug according to claim 9, characterized in that: The preparation method of the metal detectable earplug comprises the following steps: weighing various materials, adding them into a kneader, crushing and melting them, injecting them into an injection molding machine, extruding them into a mold, and injection molding to obtain the metal detectable earplug.

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