Constrained mode damping metal plate having foamed cells and method of manufacturing the same

Abstract

The present invention provides a constrained damping metal plate having foamed holes and a manufacturing method thereof. The constrained damping metal plate having foamed holes of the present invention includes a lower metal plate, a foamed resin film bonded on the lower metal plate, and an upper metal plate bonded on the foamed resin film, wherein the foamed resin film contains, in terms of weight % by itself, a thermoplastic polyethylene resin having a number average molecular weight of 8000 to 12000: 85-95%, stearic acid: 0.1-1%, styrene-ethylene-butadiene-styrene (SEBS) resin: 1-5%, foaming agent: 0.5-5%, dicumyl peroxide crosslinking agent: 1-4%, foaming aid ZnO: 0.5-2%.

Description

Cross-references to related applications

[0001] This application is a divisional application of Chinese Patent Application No. 2021800661479, filed on September 13, 2021, entitled "Constrained Vibration-Damping Metal Plate with Foamed Holes and Method for Manufacturing the Same". This application claims priority to KR10-2020-0124880 (September 25, 2020). Technical Field

[0002] This invention relates to the manufacture of a constrained vibration damping metal plate with foamed pores, and more specifically, to a constrained vibration damping metal plate with foamed pores and a method thereof, wherein the constrained vibration damping metal plate is foamed and cooled after bonding a foamed resin film between metal plates, thereby achieving the effect of controlling vibration and blocking noise. Background Technology

[0003] Generally, vibration-damping steel plates are divided into two types: constrained composite steel plates made by laminating resin between two steel plates, and non-constrained vibration-damping steel plates that function to block noise or vibration by coating or laminating resin onto a single steel plate. In the case of the non-constrained type, the manufacturing process is simple due to the two-layer structure; however, compared to the constrained type, the vibration-damping effect is relatively reduced, resulting in poorer performance as a vibration-damping steel plate. Therefore, most vibration-damping steel plates have a constrained structure.

[0004] In other words, although the forms of vibration reduction effects of constrained and unconstrained types differ, in the case of constrained vibration-damping steel plates, the shear deformation of the resin layered between the steel plates absorbs external vibrations or noise applied to the steel plates as heat energy, thereby reducing vibration or noise. Conversely, in the case of unconstrained vibration-damping steel plates, the expansion and contraction deformation of the resin coated on the steel plates absorbs external vibrations or noise applied to the steel plates as heat energy, thereby reducing vibration or noise.

[0005] This type of vibration-damping steel plate can be widely used in the outer panels of household appliances that generate a lot of noise, such as refrigerators, washing machines, and air purifiers; oil pans in engine parts, which are the main source of noise in automobiles; dashboards and other automotive components; precision instruments; building materials, and other applications.

[0006] However, existing vibration-damping steel plates achieve their vibration-damping performance by inserting thermoplastic polymer resins such as polyethylene into the steel plate in the form of a sandwich panel or by coating it with liquid polymer resin. That is, typically, polymer resins such as polyester (Japanese Patent Application Laid-Open No. 51-93770), polyamide (Japanese Patent Application Laid-Open No. 56-159160), ethylene / α-olefin, and cross-linked polyolefin (Japanese Patent Application Laid-Open No. 59-152847) are used to ensure vibration-damping performance, but there are limitations when applying them to household appliances or automobiles that generate a lot of noise. Summary of the Invention

[0007] Technical problems to be solved The purpose of this invention is to provide a constrained vibration-damping metal plate. In order to improve the vibration-damping performance, the metal plate not only utilizes the viscoelastic properties of polymer resin, but also utilizes the effect of foaming pores. Through the vibration / noise blocking effect of the viscoelastic properties of polymer resin and foaming pores, the vibration-damping performance and sound insulation performance are achieved, thereby minimizing the vibration / noise of the product.

[0008] Furthermore, the technical problem to be solved by the present invention is not limited to the technical problems mentioned above. Those skilled in the art can clearly understand other technical problems not mentioned through the following description.

[0009] Technical solution One aspect of the present invention relates to a constrained vibration-damping metal plate having foamed pores, comprising: Lower metal plate; A foamed resin film, which is bonded to the lower metal plate; and The upper metal plate is bonded to the foamed resin film. The foamed resin film, by its own weight percentage, comprises: thermoplastic polyethylene resin with a number average molecular weight of 8,000 to 12,000: 85-95%, stearic acid: 0.1-1%, styrene-ethylene-butadiene-styrene (SEBS) resin: 1-5%, foaming agent: 0.5-5%, dicumyl peroxide crosslinking agent: 1-4%, and foaming aid ZnO: 0.5-2%.

[0010] Furthermore, another aspect of the present invention provides a method for manufacturing a constrained vibration-damping metal plate having foamed pores, comprising the following processes: Prepare a foamed resin film having the foamed resin composition as described above; The prepared foamed resin film is stacked between two metal plates, and then the laminate is joined by rolling while maintaining a first heating zone at a temperature of 130-150°C. The laminated material, formed by roll pressing, is passed through a second heating zone maintained in a temperature range of 150-190°C to allow the foaming agent to foam, thereby forming foam pores within the foamed resin film; and The laminate with foamed pores is cooled to room temperature.

[0011] The foaming agent can be an azodicarbonamide-based powder foaming agent.

[0012] The thickness of the foamed resin film can be in the range of 50-250 μm.

[0013] The metal plate may be selected from cold-rolled steel plate, hot-rolled steel plate, galvanized steel plate, galvanized alloy steel plate, stainless steel plate and aluminum plate.

[0014] In the continuous manufacturing process, the line speed is preferably controlled at 0.5-5 m / min.

[0015] Beneficial effects The present invention, as described above, can effectively provide a constrained vibration damping metal plate with foamed pores. The metal plate is cooled by foaming a foaming agent after a foaming resin film is bonded between the metal plates, thereby achieving the effect of controlling vibration and blocking noise. Attached Figure Description

[0016] Figure 1 This is a manufacturing process diagram of a constraint-type vibration-damping metal plate according to one embodiment of the present invention.

[0017] Figure 2 This is a cross-sectional schematic diagram showing the cross-section of a metal plate manufactured according to different vibration-damping steel plate manufacturing processes of the present invention.

[0018] Figure 3 This is a diagram illustrating the modal evaluation method for measuring vibration reduction performance. Detailed Implementation

[0019] The present invention will now be described.

[0020] This invention is a technique for improving the vibration damping performance of metal plates by applying foaming pores to a coating. Specifically, it is characterized by exposing the foaming pores to the noise / vibration source, thereby blocking the generated noise / vibration within the pores and thus improving the vibration damping performance of the metal plate.

[0021] This constrained vibration damping metal plate of the present invention comprises: a lower metal plate; a foamed resin film bonded to the lower metal plate; and an upper metal plate bonded to the foamed resin film, wherein, by weight percent, the foamed resin film comprises: 85-95% thermoplastic polyethylene resin with a number average molecular weight of 8000 to 12000, 0.1-1% stearic acid, 1-5% styrene-ethylene-butadiene-styrene (SEBS) resin, 0.5-5% foaming agent, 1-4% dicumyl peroxide crosslinking agent, and 0.5-2% ZnO as a foaming aid.

[0022] First, the constraint-type vibration-damping metal plate of the present invention includes an upper metal plate and a lower metal plate to be bonded to both sides of a foamed resin film. In the present invention, the upper metal plate and the lower metal plate can be selected from cold-rolled steel plate, hot-rolled steel plate, galvanized steel plate, galvanized alloy steel plate, stainless steel plate and aluminum plate, respectively, and the thickness of the metal plates can be 0.2-2.0 mm.

[0023] Furthermore, the vibration-damping metal plate of the present invention includes a foamed resin film formed between the two metal plates. By weight percent, the foamed resin film comprises: 85-95% thermoplastic polyethylene resin with a number average molecular weight of 8000 to 12000, 0.1-1% stearic acid, 1-5% styrene-ethylene-butadiene-styrene (SEBS) resin, 0.5-5% foaming agent, 1-4% dicumyl peroxide crosslinking agent, and 0.5-2% ZnO as a foaming aid. Hereinafter, unless otherwise stated, "%" refers to "by weight".

[0024] By weight, the foamed resin film of the present invention contains 85-95% thermoplastic polyethylene resin with a number average molecular weight of 8,000 to 12,000. When the number average molecular weight is less than 8,000, the film is too soft and difficult to maintain strength as a vibration-damping steel plate. However, when the number average molecular weight exceeds 12,000, it may be difficult to form foam cells due to its excessive rigidity. Furthermore, since the foamed resin film of the present invention contains 85-95% polyethylene resin, if this content range is exceeded, it may be difficult to function as a vibration-damping steel plate due to insufficient amounts of other additives.

[0025] Furthermore, the foamed resin film of the present invention contains 0.1-1% stearic acid to improve the melt workability of polyethylene when molten polyethylene resin is added. Adding less than 0.1% stearic acid does not help the melt workability of polyethylene resin; on the contrary, adding more than 1% stearic acid may hinder the physical properties of the polyethylene film.

[0026] Furthermore, the foamed resin film of the present invention contains 11-5% styrene-ethylene-butadiene-styrene (SEBS) resin to improve the adhesion between the upper and lower metal plates and the polyethylene film. When the SEBS resin content is less than 1%, the effect on improving adhesion is small; conversely, when the SEBS resin content exceeds 5%, the film has high softness and may be uneconomical.

[0027] Furthermore, the foamed resin film of the present invention contains 0.1-5% of a foaming agent for forming pores. When the content of the foaming agent is less than 0.1%, the amount of gas generated is insufficient; when the content of the foaming agent exceeds 5%, the foaming efficiency is excellent due to the increased amount of gas generated, but it may be difficult to maintain the strength as a vibration damping steel plate.

[0028] In this invention, the powdered foaming agent shown in Table 1 below, namely azodicarbonamide, can be used as the foaming agent.

[0029] Alternatively, the foaming agent can also be a capsule foaming agent containing a foaming agent in a thermoplastic acrylonitrile-based resin shell structure as shown in Table 2 below.

[0030] [Table 1]

[0031] [Table 2]

[0032] Furthermore, the foamed resin film of the present invention contains a crosslinking agent to protect the shape of the foam pores generated in the plastic resin, preferably using dicumyl peroxide as shown in Table 3 below. In this case, the added content is preferably limited to 1-4%. When the added content is less than 1%, it is difficult to function as a crosslinking agent due to insufficient addition; conversely, when the added content exceeds 4%, the increased degree of crosslinking may lead to a decrease in foaming rate due to the formation of crosslinked portions before the formation of foam pores.

[0033] [Table 3]

[0034] Furthermore, the foamed resin film of the present invention contains 0.5-2% ZnO as a foaming aid.

[0035] When manufacturing vibration-damping steel plates, prolonged foaming at temperatures above 200°C for extended periods within a foamed resin film can alter the rigidity of the metal material or cause heat damage to the polymer resin, leading to economic disadvantages. Therefore, it is necessary to minimize the foaming temperature. Typically, azodicarbonamide, used as a foaming agent, decomposes at 205°C. Since the foaming agent decomposes at 150-170°C when ZnO is added, it prevents losses in processing temperature and enhances the crosslinking effect of the crosslinking agent.

[0036] Therefore, the foamed resin film of the present invention contains 0.5-2% ZnO as a foaming aid to reduce the decomposition temperature of the foaming agent. When the amount of ZnO added is less than 0.5%, the effect of reducing the decomposition temperature is insufficient. When the amount of ZnO added exceeds 2%, the added ZnO may hinder the formation of foam pores.

[0037] Next, the method for manufacturing the constraint-type vibration-damping metal plate of the present invention will be described.

[0038] The method for manufacturing a constraint-type vibration-damping metal plate according to the present invention includes the following processes: preparing a foamed resin film having a foamed resin composition as described above; laminating the prepared foamed resin film between two metal plates, and then bonding the laminate by rolling it through a first heating zone maintained at a temperature of 130-150°C; passing the roll-bonded laminate through a second heating zone maintained at a temperature range of 150-190°C to foam the foaming agent, thereby forming foam pores in the foamed resin film; and cooling the laminate with the formed foam pores to room temperature.

[0039] Figure 1 This is a manufacturing process diagram of a constraint-type vibration-damping metal plate according to one embodiment of the present invention.

[0040] like Figure 1 As shown, the method for manufacturing the constraint-type vibration-damping metal plate of the present invention generally includes, in sequence, a foaming film manufacturing process, a film bonding process, a film foaming process, and a cooling and compression process.

[0041] First, in this invention, a composition consisting of a polymer resin having the composition shown above and a foaming material is uniformly mixed in a mixer according to a hot melting method and then extruded into a film.

[0042] Specifically, the mixing sequence of these compositions is as follows: First, polyethylene resin with a number average molecular weight of 8000 to 12000 is melted at 140°C, and then 0.1-1% by weight of stearic acid is mixed in. Next, 1-5% of styrene-ethylene-butadiene-styrene (SEBS) is mixed in. Then, 0.1-10% of a foaming agent and 0.5-2% of ZnO as a foaming aid are mixed in. Finally, 1-4% of dicumyl peroxide as a crosslinking agent is added and uniformly mixed to prepare a foamed resin composition. The prepared resin composition is then used to manufacture a film through a T-die of an extruder, and foaming should not occur during film manufacturing.

[0043] In this invention, the thickness of the membrane is preferably controlled within the range of 50-250 μm. When the membrane thickness is less than 50 μm, the membrane is too thin, resulting in insufficient vibration damping performance of the damping steel plate. When the membrane thickness exceeds 250 μm, although the vibration damping performance is excellent, the membrane thickness is too thick, which may lead to poor processability.

[0044] Next, in this invention, the prepared foamed resin film is laminated between two metal plates, and then the laminate is joined by rolling while maintaining a first heating zone at a temperature of 130-150°C. That is, after inserting the film between the metal plates and the metal, the metal and the foamed film are pressed and bonded by rolling in a first heating zone at a temperature above the melting point of the polymer resin.

[0045] In this invention, a continuous manufacturing process is used, in which the manufactured foamed resin film is inserted between metal plates and bonded by rolling through a first heating zone at 130-150°C above the melting point of polyethylene resin.

[0046] Furthermore, in this invention, the laminated material, which is roll-bonded, is subjected to a second heating zone maintained in a temperature range of 150-190°C to cause the foaming agent to foam, thereby forming foam pores within the foaming resin film.

[0047] That is, when the roll-bonded laminate is passed through a second heating zone at 150-190°C, the foaming agent decomposes and the film foams simultaneously. At this time, the extrusion roller is only squeezed by the weight of the roller, thus allowing for sufficient foaming.

[0048] In this foaming process, the foaming agent of the pre-mixed polymer film is decomposed in a second heating zone within the temperature range where the foaming agent is decomposed, and foaming of the polymer film is formed between metal plates. In this invention, the foaming pores are formed by uniformly mixing the foaming agent in the thermoplastic polymer resin using a chemical foaming method, and then using the gas generated by decomposing the foaming agent at a certain temperature for foaming.

[0049] Finally, in this invention, the laminate with the foamed pores is cooled to room temperature. After the foaming process of the foamed resin film described above, the temperature when passing through the cooling zone is room temperature, and the gap of the extrusion rollers is adjusted according to the required thickness of the product to manufacture the product. Generally, it is considered that 100% to 300% of the thickness of the film before foaming is the optimal choice to maintain the vibration damping performance and strength as a vibration damping steel plate.

[0050] Figure 2 This is a cross-sectional schematic diagram showing the cross-section of a metal plate manufactured according to different vibration-damping steel plate manufacturing processes of the present invention.

[0051] Furthermore, in this invention, during the continuous manufacturing process of the aforementioned vibration-damping metal plate, the linear speed is preferably controlled at 0.5-5 m / min. When the linear speed is less than 0.5 m / min, productivity may decrease; when the linear speed exceeds 5 m / min, it may be difficult to form the foamed polyethylene resin layer. Detailed Implementation

[0052] The present invention will be described in detail below through examples.

[0053] (Example) Polyethylene resin with a number average molecular weight of 8000 to 12000 was melted at 140°C, and then 0.1-1% (by weight) of stearic acid was mixed in. 1-5% of styrene-ethylene-butadiene-styrene (SEBS) resin was mixed in, followed by 0.5-2% of azodicarbonamide as a powder blowing agent and ZnO as a blowing aid. Finally, 1-4% of dicumyl peroxide as a crosslinking agent was added and the mixture was homogeneously mixed to prepare a foamed resin composition. As shown in Tables 3 and 4 below, foamed resin compositions were prepared by varying the content of the blowing agent. The prepared resin compositions were then used to manufacture a foamed resin film with a thickness of 100 μm using a T-die of an extruder.

[0054] Furthermore, the foamed resin film manufactured as described above is inserted and laminated between 0.5T galvanized steel sheets, and then the laminate is rolled together by rolling while maintaining a first heating zone at a temperature of 130-150°C. Next, the rolled-bonded laminate is passed through a second heating zone maintained at a temperature range of 150-190°C to foam the foaming agent, thereby forming foam pores within the foamed resin film. Finally, the laminate with the formed foam pores is cooled to room temperature, ultimately producing a constraint-type vibration-damping steel sheet.

[0055] For each vibration-damping steel plate thus manufactured, the foaming performance of the foam film was evaluated based on the content of the foaming agent, and the results are shown in Table 4 below.

[0056] Furthermore, the loss factor was measured based on the foaming agent content, and the value is shown in Table 5 below. Vibration damping performance is a quantity representing the ability to convert vibrational energy into heat energy when vibration is applied to a material. As a measure of this vibration damping performance, the loss factor (η), which has the same meaning as internal friction, is used. The loss factor η is defined by the following equation 1, where the total vibrational energy of the vibrating system is E, and the energy dissipated as heat energy in one cycle of vibration is ΔE.

[0057] [Relation 1] η = ΔE / 2πE (η ≤ 1) In addition, using Figure 3 Modal evaluation, as a method for measuring the loss coefficient, is a form of vibration testing. It measures the loss coefficient by analyzing the vibration characteristics generated after impacting a specimen with a hammer using an impact test, thereby assessing vibration reduction performance. Generally, a higher loss coefficient indicates better vibration reduction performance.

[0058] Furthermore, when each manufactured vibration damping steel plate is bent at 90°, the resin layer and galvanized steel plate are visually observed for peeling and the retention of the 90° shape to determine the processability of the vibration damping steel plate. The results are shown in Table 5 below. Additionally, the judgment criteria are divided into good (no peeling, retains 90° shape), average (no peeling, insufficient retention of 90° shape), and poor (peeling).

[0059] [Table 4]

[0060] [Table 5]

[0061] As shown in Tables 4 and 5, it can be seen that when vibration-damping steel plates are bonded together with foamed resin films containing 0.1-5% of the foaming agent component of the present invention, not only are the foaming rates within an appropriate range (50-300%), but the loss coefficient is also high and the processability is excellent. Conversely, it can be seen that when the foaming agent content is less than 0.1%, the foaming rate is insufficient, and when the foaming agent content exceeds 5%, the processability is poor.

[0062] As described above, preferred embodiments of the present invention have been presented in the detailed description of the invention. However, those skilled in the art can make various modifications without departing from the scope of the invention. Therefore, the scope of the invention is not limited to the described embodiments and should be determined by the claims and their equivalents.

Claims

1. A constrained vibration damping metal plate with foamed pores, comprising: Lower metal plate; A foamed resin film, which is directly bonded to the lower metal plate; as well as The upper metal plate is directly bonded to the foamed resin film. The foamed resin film, by its own weight percentage, comprises: thermoplastic polyethylene resin with a number average molecular weight of 8000 to 12000: 85-95%, stearic acid: 0.1-1%, styrene-ethylene-butadiene-styrene (SEBS) resin: 1-5%, foaming agent: 0.5-5%, dicumyl peroxide crosslinking agent: 1-4%, and foaming aid ZnO: 0.5-2%. The foaming rate of the foamed resin film is 50% to 300%.

2. The constrained vibration damping metal plate with foamed pores according to claim 1, characterized in that, The foaming agent is an azodicarbonamide-based powder foaming agent.

3. The constrained vibration damping metal plate with foamed pores according to claim 1, characterized in that, The foaming agent is a capsule foaming agent containing a foaming agent in a thermoplastic acrylonitrile-based resin shell structure.

4. The constrained vibration damping metal plate with foamed pores according to claim 1, characterized in that, The metal plate is selected from cold-rolled steel plate, hot-rolled steel plate, galvanized steel plate, galvanized alloy steel plate, stainless steel plate and aluminum plate.

5. The constrained vibration damping metal plate with foamed pores according to claim 1, characterized in that, The thickness of the foamed resin film ranges from 50 to 250 μm.

Images