Stiffness-improved engine compartment insulation for electric cars

Abstract

The present invention is configured by integrally laminating a chemical nonwoven fabric and (corrugated) kraft paper on both sides of a polyurethane foam sheet. This allows for not only reinforcing rigidity by increasing elongation through the (corrugated) kraft paper, but also satisfying the eco-friendliness required for ESG management by enabling the recycling of the paper material. Furthermore, the use of (corrugated) kraft paper allows for easy molding of engine room sound-absorbing materials with complex shapes, thereby improving sound absorption performance in high-frequency ranges of 2,000 Hz or higher through improved moldability and rigidity. Additionally, by using a polyolefin-based binder to attach the polyurethane foam sheet and (corrugated) kraft paper, the present invention can improve moldability, rigidity, and sound absorption performance by increasing the adhesive strength of the (corrugated) kraft paper through a polyolefin-based binder that is similar to the molding temperature conditions of the polyurethane foam.

Description

Technology Field

[0001] The present invention relates to a sound-absorbing material for an electric vehicle engine room with improved rigidity. More specifically, by integrally laminating a chemical nonwoven fabric on one side of a polyurethane foam sheet and kraft paper or corrugated kraft paper on the other side, the rigidity can be reinforced through the kraft paper or corrugated kraft paper, and moldability can be improved by increasing elongation, as well as sound absorption performance in the high-frequency range of 2,000 Hz or higher. At this time, recycled or regenerated paper is added to the kraft paper or corrugated kraft paper to make it environmentally friendly while further improving the rigidity reinforcement and sound absorption performance. In addition, by attaching a polyolefin-based thermoplastic binder between the polyurethane foam sheet and the kraft paper or corrugated kraft paper, the adhesive strength can be increased while matching the molding conditions of the polyurethane foam. Background Technology

[0002] Generally, as shown in [Fig. 1], engine room insulation, which is typically installed in fossil fuel vehicles, is installed inside the engine room of an electric vehicle. Examples of the engine room insulation include, for instance, a hood (H), a dashboard panel (D), and a cover (E) installed on the underside of the power generation unit. This engine room insulation is configured to control noise and heat generated within the engine room and reduce their release to the outside, thereby reducing engine noise during driving, protecting the engine and surrounding components, and creating a comfortable interior environment.

[0004] The following (Patent Document 1) to (Patent Document 3) disclose technology related to such engine room insulation.

[0005] (Patent Document 1) Korean Published Patent No. 10-2024-0015796

[0006] By adding nanocellulose when manufacturing polyurethane foam, the sound absorption performance of the polyurethane foam in the high-frequency range of 3,000 to 5,000 Hz can be improved, and the rigidity of the polyurethane foam can be reinforced through the nanocellulose, thereby enabling stable use. In particular, by adding nanocellulose such that the amount of added nanocellulose accounts for 0.5 to 2 weight percent of the total weight percent of the polyurethane foam, the sound absorption material for an electric vehicle engine room can reinforce rigidity while minimizing the increase in the weight of the polyurethane foam. Furthermore, since low-density polyurethane can be used as rigidity is reinforced, the total weight of the sound absorption material for an electric vehicle engine room can be reduced, thereby improving the fuel efficiency of the electric vehicle.

[0008] (Patent Document 2) Korean Published Patent No. 10-2023-0004980

[0009] As the polyurethane is manufactured with densities of 11–13 kg / m³ and 16–20 kg / m³, respectively, the sound absorption performance is similar in the mid-low frequency range of 800–1,600 Hz, but the sound absorption performance can be improved by about 20% in the high frequency range of 3,000 Hz or higher. In addition, as the polyurethane is manufactured with densities of 11–13 kg / m³ and 14–16 kg / m³, respectively, not only is sound absorption performance exhibited in the mid-low frequency range of 1,000–2,000 Hz, but the sound absorption performance in the high frequency band of 3,000 Hz can also be improved by about 18%. At this time, when bonding polyurethanes with different densities, a polyester web adhesive can be used to obtain a breathability effect along with sound absorption performance, or by applying TPO elastomer as an adhesive, sound insulation performance can be improved along with sound absorption performance.

[0011] (Patent Document 3) Korean Published Patent No. 10-2015-0072551

[0012] The purpose is to provide an automotive engine room insulation that improves sound absorption and insulation performance relative to the weight increase of the polyurethane foam by modifying the cell structure of the polyurethane foam, which primarily functions as a sound-absorbing material, through the addition of carbon nanotubes (CNT) during manufacturing. In particular, another purpose is to provide an automotive engine room insulation with excellent sound absorption performance relative to the weight increase by manufacturing this polyurethane foam using the same process as conventional polyurethane foam, but by adding only carbon nanotubes to the polyurethane foam base liquid.

[0014] Meanwhile, conventional engine room insulation made in this way is made only of sound-absorbing material as shown in [Fig. 2], or is made of a multi-layer structure using other sound-absorbing or sound-insulating materials including this sound-absorbing material. At this time, the sound-absorbing material is mainly manufactured by integrally attaching chemical nonwoven fabrics (2, 3) to both sides of two types of polyurethane foam sheets (1', 1") with different densities. Prior art literature

[0015] Korean Published Patent No. 10-2024-0015796 (Publication Date: 2024.02.06) Korean Published Patent No. 10-2023-0004980 (Publication Date: 2023.01.09) Korean Published Patent No. 10-2015-0072551 (Publication Date: 2015.06.30) The problem to be solved

[0016] However, the conventional sound-absorbing materials used in these engine rooms have the following problems.

[0017] (1) Polyurethane foam material is not only lightweight, but also has excellent sound absorption performance in the frequency range of 1,000 to 2,000 Hz, but its sound absorption performance is poor in the high frequency range of 2,000 Hz or higher.

[0018] (2) This is because, when the electric vehicle's motor and surrounding devices rotate at high RPM, high frequencies of approximately 2,000 Hz or higher are generated, so if conventional sound-absorbing materials are applied to the electric vehicle, sufficient sound absorption performance cannot be obtained.

[0019] (3) In addition, chemical nonwoven fabric can protect the surface of the polyurethane foam sheet from contamination of the product, but it cannot reinforce or improve the strength of the polyurethane foam. This weakens the overall rigidity of the engine room sound-absorbing material, which may cause it to tear or break easily.

[0020] (4) And, existing engine room sound-absorbing materials that lack strength like this have disadvantages in product manufacturing, such as deformation or bending after molding due to the lack of strength.

[0022] The present invention takes these points into consideration and aims to provide an engine room sound-absorbing material for electric vehicles with improved rigidity, which is configured by integrally laminating a chemical nonwoven fabric and kraft paper or corrugated kraft paper on each side of a polyurethane foam sheet, thereby not only reinforcing rigidity by increasing elongation through the kraft paper or corrugated kraft paper but also satisfying the eco-friendliness required for ESG management by allowing the paper material to be recycled.

[0023] In addition, the present invention has another objective of providing an engine room sound-absorbing material for electric vehicles with improved rigidity, which allows for the easy molding of engine room sound-absorbing materials of complex shapes through the use of such kraft paper or corrugated kraft paper, thereby improving sound absorption performance in the high-frequency range of 2,000 Hz or higher through improved moldability and rigidity.

[0024] Furthermore, another objective of the present invention is to provide an engine room sound-absorbing material for electric vehicles with improved rigidity, which can improve moldability, rigidity, and sound absorption performance by using a polyolefin-based binder to attach a polyurethane foam sheet and kraft paper or corrugated kraft paper, thereby increasing the adhesive strength of the kraft paper or corrugated kraft paper through a polyolefin-based binder similar to the molding temperature conditions of the polyurethane foam. means of solving the problem

[0025] The sound-absorbing material for an electric vehicle engine room with improved rigidity according to the present invention for achieving these purposes is,

[0026] Chemical nonwoven fabric (10);

[0027] Polyurethane foam sheet (20);

[0028] Polyolefin binder (30); and

[0029] Kraft paper or pleated kraft paper (40);

[0030] It is characterized by being formed as a single unit by stacking in sequence.

[0031] In particular, the polyolefin-based binder (30) is characterized as being a thermoplastic adhesive, a hot melt adhesive, or a hot melt film.

[0032] In addition, the above kraft paper or corrugated kraft paper (40) is characterized by having recycled or regenerated paper accounting for 10 to 30 percent of the total weight.

[0033] Finally, the polyurethane foam sheet (20) has a density of 12 to 18 kg / m³; the polyolefin-based binder (30) has an area density of 10 to 30 g / m²; and the kraft paper or corrugated kraft paper (40) has an area density of 60 to 150 g / m². Effects of the invention

[0034] The sound-absorbing material for an electric vehicle engine room with improved rigidity according to the present invention has the following effects.

[0035] (1) By integrally laminating chemical nonwoven fabric and kraft paper or corrugated kraft paper on both sides of a polyurethane foam sheet to manufacture an engine room sound-absorbing material, the rigidity of the engine room sound-absorbing material is reinforced by increasing the elongation of the kraft, thereby preventing it from being easily torn or damaged.

[0036] (2) In particular, by using kraft paper or corrugated kraft paper, the overall thickness can be made thin, so when forming into complex shapes or shapes that can improve sound absorption performance, it is not only easy to form, but complex shapes can also be made into desired shapes.

[0037] (3) In addition, the above kraft paper or corrugated kraft paper can satisfy the eco-friendliness required for ESG management by using recycled or recycled paper in an amount of 10 to 30 percent of the total weight of the kraft paper or corrugated kraft paper, thereby allowing the recycling of paper materials collected from industrial waste.

[0038] (4) Meanwhile, by attaching the polyurethane foam sheet and the kraft paper or corrugated kraft paper with a polyolefin-based binder, the adhesion between the polyurethane foam sheet and the kraft paper or corrugated kraft paper can be increased by using a binder similar to the molding temperature conditions of the polyurethane foam.

[0039] (5) And the sound-absorbing material for an electric vehicle engine room with improved rigidity according to the present invention can improve sound absorption performance in the high frequency range of 2,000 Hz or higher. Brief explanation of the drawing

[0040] [Fig. 1] is a side view of a car showing the mounting location of an engine room sound-absorbing material installed in the engine room of a conventional car. [Fig. 2] is a diagram showing the configuration of an engine room sound-absorbing material installed in the engine room of a conventional automobile, and is a cross-sectional view of an engine room sound-absorbing material in which the density of the polyurethane foam sheet in (a) is higher than the density of the polyurethane foam sheet in (b). [Fig. 3] is a cross-sectional view showing the layer structure of an engine room sound-absorbing material for an electric vehicle with improved rigidity according to the present invention. [Fig. 4] is a graph showing the absorption performance (Absorption Coefficient) according to the change in frequency (1 / 3 Octave Center Frequency [Hz]) for Comparative Example #1 and Comparative Example #2, which consist of an engine room sound absorbing material for an electric vehicle with improved rigidity according to the present invention (Example) and a conventional engine room sound absorbing material for an automobile. Specific details for implementing the invention

[0041] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention in accordance with the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0042] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0044] [Composition of Sound Absorbing Material for Electric Vehicle Engine Rooms with Improved Rigidity]

[0045] The sound-absorbing material for an electric vehicle engine room with improved rigidity according to the present invention is formed integrally by laminating in the order of a chemical nonwoven fabric (10), a polyurethane foam sheet (20), a polyolefin-based binder (30), and kraft paper or corrugated kraft paper (40), as shown in FIG. 3 and FIG. 4.

[0046] In particular, the use of the above kraft paper or corrugated kraft paper (40) not only reinforces the rigidity of the engine room sound-absorbing material according to the present invention, but also increases the elongation rate so that complex shapes can be easily and accurately formed, thereby improving sound absorption performance.

[0047] In addition, by using a kraft paper or corrugated kraft paper (40) in which recycled or recycled paper is added in an amount of 10 to 30 percent of the total weight, the paper material collected from industrial waste can be recycled, thereby satisfying the eco-friendliness required for ESG management.

[0048] And the polyurethane foam sheet (20) and the kraft paper or corrugated kraft paper (40) are configured to be integrally attached with a polyolefin-based binder (30), thereby using a binder similar to the molding temperature conditions of the polyurethane foam, so that the adhesive strength between the polyurethane foam sheet (20) and the kraft paper or corrugated kraft paper (40) can be increased.

[0049] Finally, the polyurethane foam sheet (20) is used with a density of 12 to 18 kg / m³, the polyolefin-based binder (30) is used with an area density of 10 to 30 g / m², and the kraft paper or corrugated kraft paper (40) is used with an area density of 60 to 150 g / m², thereby improving the sound absorption performance in the high frequency range of 2,000 Hz or higher.

[0051] The following is a more detailed explanation of this configuration with reference to the attached drawings.

[0052] go. Chemical non-woven fabric

[0053] The chemical nonwoven fabric (10) is attached integrally to the surface of the polyurethane foam sheet (20) to be described later, as shown in [Fig. 3].

[0055] Here, the chemical nonwoven fabric (20) refers to a nonwoven fabric manufactured by allowing an adhesive to penetrate the fibers and drying them when bonding a web made of fibers such as PET (polyethylene terephthalate) fibers. At this time, the penetration of the adhesive into the fibers can be achieved through a immersion bonding method, which creates adhesive by immersing the web, or a spray bonding method, which creates adhesive by spraying the adhesive. This chemical nonwoven fabric (20) is well known to be used as a clothing interlining and coating foam, etc., due to its excellent flexibility and breathability.

[0057] These chemical nonwoven fabrics (20) protect the surface of the polyurethane foam sheet (20) and the engine room sound-absorbing material from contamination.

[0059] B. Polyurethane foam sheet

[0060] The polyurethane foam sheet (20) is laminated facing the chemical nonwoven fabric (10) described above, as shown in [Fig. 3]. Here, polyurethane foam is flexible, lightweight, highly durable, and can be manufactured in various shapes and densities, so it is used in various industrial fields, and is particularly well known to be effective in blocking heat and noise and absorbing shock as a cushioning material.

[0062] In a preferred embodiment of the present invention, it is preferable to use a polyurethane foam sheet (20) having a density of 12 to 18 kg / m³. This is to enable improved sound absorption performance in the high-frequency range of 2,000 Hz or higher when laminated with other components and manufactured as a single unit.

[0064] C. Polyolefin-based binder and Kraft paper or wrinkles Kraft paper

[0065] Kraft paper or corrugated kraft paper (40) is attached to the surface of the aforementioned polyurethane foam sheet (20) as shown in [Fig. 3]. At this time, a polyolefin-based binder (30) is inserted between the polyurethane foam sheet (20) and the kraft paper or corrugated kraft paper (40) to bond them together.

[0067] Here, by using a thermoplastic adhesive, hot melt adhesive, or hot melt film as the polyolefin-based binder (30), the kraft paper or corrugated kraft paper (40) can be firmly adhered to the surface of the polyurethane foam sheet (20) by using a binder that matches the molding temperature conditions for molding the polyurethane foam. In addition, it is preferable to use a polyolefin-based binder (30) with a surface density of 10 to 30 g / m² so that the adhesive strength can be maximized and the sound absorption performance can be improved in conjunction with other components.

[0069] Meanwhile, the above-mentioned kraft paper or corrugated kraft paper (40) is mounted in close contact with the surface of the aforementioned polyurethane foam sheet (20) via the polyolefin-based binder (30) as shown in [Fig. 3]. Here, kraft paper refers to brown paper made of unbleached kraft pulp (sulfate pulp) processed into a corrugated shape, manufactured using conventional technology to ensure it does not tear easily and can also strengthen rigidity. Corrugated kraft paper refers to kraft paper formed into a wave or corrugated shape to increase elongation and further reinforce rigidity. At this time, it is preferable to use kraft paper or corrugated kraft paper (40) with a surface density of 60 to 150 g / m² so that rigidity reinforcement and sound absorption performance can be improved together with other components. In addition, it is desirable to manufacture the kraft paper or corrugated kraft paper (40) by adding recycled or regenerated paper in an amount of 10 to 30 percent of the total weight of the kraft paper or corrugated kraft paper (40), thereby enabling the recycling of paper materials collected from industrial waste and satisfying the eco-friendliness required for ESG management.

[0071] Meanwhile, the test results evaluating the sound absorption performance of the sound-absorbing material for an electric vehicle engine room with improved rigidity according to the present invention are as follows.

[0072] (Sound absorption performance evaluation)

[0073] Sound absorption performance was evaluated by detecting sound absorption performance according to frequency change for the example, comparative example #1, and comparative example #2, as shown in [Table 1] below.

[0074] Comparative Example #1 Comparative Example #2 Examples Chemical nonwoven fabric Chemical nonwoven fabric Chemical nonwoven fabric PU D18 PU D12 PU D12 Chemical nonwoven fabric Chemical nonwoven fabric Pleated kraft paper 1) PU D12: Polyurethane foam sheet with a density of 12 kg / m³. 2) PU D18: Polyurethane foam sheet with a density of 18 kg / m³.

[0076] The results of measuring sound absorption performance according to frequency change for the Example, Comparative Example #1, and Comparative Example #2 are as shown in [Fig. 4] below. In [Fig. 4], the horizontal axis represents frequency (1 / 3 Octave Center Frequency [Hz]), the vertical axis represents sound absorption performance (Absorption Coefficient), the black line represents the sound absorption performance graph of Comparative Example #1, the blue line represents the sound absorption performance graph of Comparative Example #2, and the red line represents the sound absorption performance graph of the Example.

[0078] As a result, as shown in [Fig. 5], it can be seen that the example can achieve sound absorption performance that is lower than Comparative Example #2 but higher than Comparative Example #1 in the high frequency range of 2,000 Hz or higher.

[0080] As described above, the present invention can form a composite structure that improves insufficient strength by attaching kraft paper or corrugated kraft paper to one side of a polyurethane foam sheet using a chemical nonwoven fabric and to the other side using a polyolefin-based binder, and can also produce a lightweight engine room sound-absorbing material for electric vehicles with excellent sound absorption performance in a high frequency range of 2,000 Hz or higher. Explanation of the symbols

[0081] 10: Chemical nonwoven fabric 20: Polyurethane foam sheet 30: Polyolefin binder 40: Kraft paper or pleated kraft paper

Claims

Claim 1 An engine room sound-absorbing material for an electric vehicle with improved rigidity, characterized by being formed integrally by laminating in the order of a chemical nonwoven fabric (10); a polyurethane foam sheet (20); a polyolefin-based binder (30); and a corrugated kraft paper (40), wherein the polyurethane foam sheet (20) has a density of 12-18 kg / m³, the polyolefin-based binder (30) has an area density of 10-30 g / m², and the corrugated kraft paper (40) has an area density of 60-150 g / m². Claim 2 In claim 1, the polyolefin-based binder (30) is characterized as being a thermoplastic adhesive, a hot melt adhesive, or a hot melt film, thereby providing an engine room sound-absorbing material for an electric vehicle with improved rigidity. Claim 3 In claim 1, the above-mentioned corrugated kraft paper (40) is a sound-absorbing material for an electric vehicle engine room with improved rigidity, characterized in that recycled or regenerated paper accounts for 10 to 30 percent of the total weight. Claim 4 delete

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