KR102290975B1 - Foam compositions for sound-absorbing materials with improved fire-retardancy and sound-absorption, and sound-absorbing materials for sound box using the same - Google Patents

Abstract

According to the present specification, disclosed are a foamed composition for a sound-absorbing material formed by mixing a foamable polyurethane raw material, thermoplastic resin powder, boric acid and carbon nanostructures and having improved flame retardancy and sound-absorbing properties, and a sound-absorbing material for an acoustic chamber manufactured using the foamed composition for a sound-absorbing material of the present invention.

Description

Foam compositions for sound-absorbing materials with improved fire-retardancy and sound-absorption, and sound-absorbing materials for sound box using the same}

The present invention relates to a foamed composition for a sound-absorbing material with improved flame retardancy and sound absorption and a sound-absorbing material for an acoustic chamber using the same, and more specifically, to a foamed composition for a sound-absorbing material with improved flame retardancy through uniform dispersion, stabilization, and synergistic action of the flame retardant, and the same It relates to a sound-absorbing material for an acoustic chamber used.

The acoustic room is a space for the demonstration of a performance. In order to increase the concentration of the audience or performers on the performance, noise introduced from the outside of the acoustic chamber needs to be minimized. Therefore, construction for soundproofing is usually performed from the floor to the wall and ceiling of the acoustic chamber.

Conventionally, a soundproofing material to which resinized felt, glass wool, etc. are added has been used for soundproofing construction. However, such materials need to be added by compression at a high weight in order to improve sound absorption or sound insulation performance, and have limitations in that they do not have flame retardancy, cause itchiness when in contact with the body, or that composition and physical properties are not easily controlled.

Furthermore, in the case of glass fibers, odors are continuously generated due to the aging of the fibers, and when used in a closed environment such as an acoustic room, a separate ventilation means needs to be devised, and unnecessary noise may occur due to such limitations. .

Therefore, in order to solve the above-mentioned problems, research on alternative materials for resinized felt and glass fibers has been continued. In particular, among several candidate materials, the use of polyurethane foam was considered from the viewpoint of easy securing of sound insulation and workability. Polyurethane foam foam has improved sound absorption performance compared to conventional glass fibers, and at the same time, it is easy to mold and has resistance to corrosion, so it has desirable properties to be used as a wall material of an acoustic room.

However, in the case of expanded polyurethane foam, there is a limitation in that thermal stability is inferior. As an invention for overcoming such limitations, Korean Patent Publication No. 10-2011-107675 (hereinafter, 'Patent Document 1') has been published. In the invention of Patent Document 1, CNT is added and dispersed in a stock solution of polyurethane. It is characterized in that the polyurethane foam is foamed after.

According to Patent Document 1, by the addition of CNT, the insulation, durability, and thermal stability of the polyurethane foam can be improved. However, the performance improvement of Patent Document 1 according to the addition of CNTs is only a slight improvement in thermal stability, and it is considered difficult to secure flame retardancy such as self-extinguishing properties. In the case of the acoustic room, a number of expensive equipment is not only used therein, but also a sealed environment is maintained, so that it is inevitably vulnerable to fire, so it is necessary to additionally provide flame retardancy.

In addition, the conventional polyurethane foam is known to have a relatively low sound absorption coefficient in a high frequency region of 1,500 Hz or more.

No. 10-2011-107675

The present invention has been developed to solve the above technical problem, and an object of the present invention is to provide a sound absorbing material for an acoustic chamber with improved sound absorption and flame retardancy.

On the other hand, it is a detailed object of the present invention to provide a foamed composition for a sound-absorbing material that can be used to manufacture the sound-absorbing material for an acoustic chamber.

The present inventors have devised an invention including the following configuration as a result of research in order to solve the above-described problems. Specifically, the present specification is a foamable polyurethane raw material; thermoplastic resin powder; Disclosed is a foamed composition for a sound absorbing material formed by mixing boric acid and carbon nanostructures and having improved flame retardancy and sound absorption.

In addition, in each foam composition for a sound absorbing material of the present invention, with respect to 100 parts by weight of the foamable polyurethane raw material, 15 to 35 parts by weight of the thermoplastic resin powder is included, 5 to 15 parts by weight of boric acid is included, and the carbon nanostructure is 1 It is preferable to include to 5 parts by weight.

In addition, in each foam composition for sound absorbing material of the present invention, the thermoplastic resin powder is preferably at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyvinyl chloride resin, nylon resin, phenol resin, and mixtures thereof.

In addition, in each foam composition for sound absorbing material of the present invention, the carbon nanostructure is preferably at least one selected from the group consisting of carbon black, carbon nanotubes, graphene, and derivatives thereof.

In addition, in each foam composition for sound absorbing material of the present invention, the thermoplastic resin powder includes a nylon resin, and it is preferable that 25 parts by weight of the thermoplastic resin powder is included with respect to 100 parts by weight of the foamable polyurethane raw material.

In addition, in each foam composition for sound absorbing material of the present invention, the thermoplastic resin powder contains polyvinyl chloride resin, and it is preferable that the thermoplastic resin powder is contained in 25 parts by weight with respect to 100 parts by weight of the foamable polyurethane raw material.

In addition, in each foam composition for a sound absorbing material of the present invention, the thermoplastic resin powder includes a nylon resin and a polyvinyl chloride resin, and the polyvinyl chloride and the nylon resin are preferably in a ratio of 2 to 1.

In addition, in each foam composition for a sound absorbing material of the present invention, the carbon nanostructure is carbon black, and it is preferable that 1 part by weight of the carbon nanostructure is included with respect to 100 parts by weight of the foamable polyurethane raw material.

In addition, in the foaming composition for each sound absorbing material of the present invention, with respect to 100 parts by weight of the foamable polyurethane raw material, 10 parts by weight of the nylon resin and 5 parts by weight of the polyvinyl chloride resin are included, and 1 part by weight of the carbon nanostructure is included. desirable.

On the other hand, the present invention further discloses a sound absorbing material for a sound absorbing material manufactured by using any one of the sound absorbing foam composition for the sound absorbing material of the present invention.

Through the adoption of the above-described means, the sound-absorbing material for the acoustic chamber of the present invention can provide improved flame retardancy by including both the thermoplastic resin powder and boric acid.

In addition, the sound-absorbing material for an acoustic chamber of the present invention can provide improved sound absorption in a high-frequency region of 1,500 Hz or more by including both the thermoplastic resin powder and the carbon nanostructure.

The terms used in this application are only used to describe specific examples. Therefore, for example, a singular expression includes a plural expression unless the context clearly requires it to be singular. In addition, terms such as "comprises" or "comprises" used in the present application are used to clearly indicate that there is a feature, step, function, component, or a combination thereof described in the specification, and other features It should be noted that it is not intended to preliminarily exclude the existence of elements, steps, functions, components, or combinations thereof.

Meanwhile, unless otherwise defined, all terms used herein should be regarded as having the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Accordingly, unless explicitly defined herein, certain terms should not be construed in an unduly idealistic or formal sense.

In the description of the present specification, the polyurethane foam is a type of porous polymer, and has a characteristic that it contains a large number of pores in terms of its structural characteristics. Since the sound transmitted from the outside is absorbed by a plurality of pores constituting the polyurethane foam and converted into thermal energy, the pores of the polyurethane foam are the fundamental cause of the sound absorption of the polyurethane foam.

In each description of the present specification, the term 'fine fibers' refers to fibers having an average diameter of several micrometers to several hundred micrometers. On the other hand, 'nanofiber' means a fiber whose average diameter is smaller than the lower limit of the average diameter of 'fine fiber'. On the other hand, the broad meaning of 'fiber' is general fiber, and the narrow term means fibers whose average diameter is larger than the upper limit of the average diameter of 'fine fibers'.

In addition, in each description of the present specification, 'short fiber' means a fiber whose average length is between several hundred micrometers and several tens of millimeters. As a contrasting term, ‘long fiber’ means a fiber whose average length is several hundred millimeters or more.

The present specification is a foamable polyurethane raw material; thermoplastic resin powder; Disclosed is a foamed composition for a sound absorbing material formed by mixing boric acid and carbon nanostructures and having improved flame retardancy and sound absorption. Hereinafter, each component included in the foam composition for sound absorbing material of the present invention will be described in more detail.

The present invention relates to a polyurethane foam composition that can be molded as a sound-absorbing material for an acoustic chamber and has improved sound-absorbing properties and flame retardancy. In the polyurethane foam composition of the present invention, thermoplastic resin powder, boric acid, and carbon nanostructures may be dispersed.

On the other hand, the thermoplastic resin powder contained in the polyurethane foam composition of the present invention assists in the dispersion of boric acid and/or carbon nanostructures, and increases the hardness of the polyurethane foam composition, thereby enabling use as an exterior material.

In addition, boric acid contained in the polyurethane foam composition of the present invention (Boric acid, H ₃ BO ₃ ) is used to impart flame retardancy to the sound-absorbing material for sound rooms made using the polyurethane foam composition of the present invention. Upon heating, boric acid can inhibit heat transfer by forming a coating layer inside the polyurethane foam. In addition, as described below, by mixing the flame retardant material and boric acid that do not form a coating layer, synergistic flame retardancy can be imparted to the sound absorbing material including the polyurethane foam composition of the present invention.

In addition, the carbon nanostructure contained in the polyurethane foam composition of the present invention interacts evenly with the thermoplastic resin powder and boric acid, thereby further contributing to the implementation of a foam having a uniform composition and at the same time improving the thermal stability of the foam. Therefore, according to at least one aspect of the present invention, in the polyurethane foam composition of the present invention, the carbon nanostructure may be used to assist in uniform pore formation of the polyurethane foam and to impart primary heat resistance.

In addition, in each foam composition for sound absorbing material of the present invention, with respect to 100 parts by weight of the foamable polyurethane raw material, 15 to 35 parts by weight of the thermoplastic resin powder is preferably included. For example, when the thermoplastic resin powder is added in less than 15 parts by weight, the polyurethane foam may not be able to secure sufficient hardness, and as will be described later, the uniform dispersion of boric acid and carbon nanostructures may be limited, and further , the enjoyment of synergistic flame retardancy may be limited.

Conversely, when the thermoplastic resin powder is added in excess of 35 parts by weight, there may be a problem in that the content of the polyurethane is too small. For example, there is a possibility that the pores of the polyurethane are not formed uniformly and densely, so that the sound absorption may be deteriorated, and the moldability of the polyurethane foam may also be limited.

On the other hand, in each foam composition for sound absorbing material of the present invention, it is preferable that 5 to 15 parts by weight of boric acid are included with respect to 100 parts by weight of the foamable polyurethane raw material. For example, when boric acid is included in less than 5 parts by weight, there is a fear that boric acid may not sufficiently function as a flame retardant. Conversely, when included in excess of 15 parts by weight, agglomeration occurs in the foam composition for sound absorbing material, and the bias of sound absorption and flame retardancy may be a problem, and furthermore, it is impossible to completely rule out the possibility that the heat insulation coating layer is formed early in the molding process. .

In addition, in each foam composition for sound absorbing material of the present invention, the thermoplastic resin powder is preferably at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyvinyl chloride resin, nylon resin, phenol resin, and mixtures thereof. Based on 100 parts by weight of the foamable polyurethane raw material, 15 to 35 parts by weight of the thermoplastic resin powder is preferably included. The thermoplastic resin powder of the present invention may be included in the form of nanofibers and/or microfibers, and may be included in the form of short fibers and/or long fibers.

In addition, in each foam composition for sound absorbing material of the present invention, the thermoplastic resin powder contains nylon resin and/or polyvinyl chloride, and with respect to 100 parts by weight of the foamable polyurethane raw material, 25 parts by weight of the thermoplastic resin powder is preferably included. do.

On the other hand, in the foam composition for a sound absorbing material of the present invention, the average degree of polymerization of the polyvinyl chloride resin contained in the thermoplastic resin powder is preferably 200 to 600 or more. For example, when the average degree of polymerization of polyvinyl chloride is less than 200, the radical reaction by the chloride group is limited, so it is difficult to expect a synergistic action with respect to flame retardancy. Conversely, when the average degree of polymerization of the polyvinyl chloride resin exceeds 600, agglomeration by the polyvinyl chloride resin may be observed.

The nylon resin contained in the thermoplastic resin powder may be nylon-6,6 or nylon-6, but it is preferably nylon-6,10. In the case of nylon-6,10, it has a feature that it is easy to simultaneously interact with boric acid and carbon nanostructures by securing both relatively hydrophilicity and hydrophobicity. It is thought that nylon forms an interaction such as hydrogen bonding with boric acid and carbon nanostructures, contributing to dispersion of boric acid and carbon nanostructures.

In addition, polypropylene resin or polyethylene resin powder is included in the polyurethane foam composition of the present invention to function as a binder, and may be used to increase the hardness of the polyurethane foam.

Based on 100 parts by weight of the foamable polyurethane raw material, it is preferable that 1 to 5 parts by weight of carbon nanostructures are included. When the carbon nanostructure is included in less than 1 part by weight, the securing of flame retardancy may be limited. Conversely, when the carbon nanostructure is included in excess of 5 parts by weight, the viscosity of the foamed composition is excessively increased, so that the thermoplastic resin powder and/or boric acid may rather aggregate, resulting in poor overall performance of the foam.

In each foam composition for sound absorbing material of the present invention, the carbon nanostructure may be at least one selected from nanopowders, nanotubes, nanofibers and/or nanoparticles. Nanotubes are cylindrical and contain unsaturated hexagonal rings. In some cases, nanotubes can have high tensile strength. In addition, the nanotubes may be single-walled or multi-walled.

In each foam composition for sound absorbing material of the present invention, the nanostructure may take various sizes and shapes. In the nanostructure applied to the present invention, at least one numerical value may have an average value between about 1 nm and 1 μm. Preferably, the nanostructures of the present invention have an average value of at least one dimension between about 10 nm and 100 nm. More specifically, in the nanostructures of the present invention, it is preferred that at least one numerical value has an average value between about 10 nm and 50 nm.

In addition, in each foam composition for sound absorbing material of the present invention, the carbon nanostructure is preferably at least one selected from the group consisting of carbon black, carbon nanotubes, graphene, and derivatives thereof. Based on 100 parts by weight of the foamable polyurethane raw material, it is preferable that 1 to 5 parts by weight of carbon nanostructures are included. As described above, when the carbon nanostructure is included in an amount of less than 1 part by weight, securing of flame retardancy may be limited. Conversely, when the carbon nanostructure is included in excess of 5 parts by weight, the viscosity of the foamed composition is excessively increased, so that the thermoplastic resin powder and/or boric acid may rather aggregate, resulting in poor overall performance of the foam.

In addition, in each of the foam compositions for sound absorbing materials of the present invention, in the case of carbon black as the carbon nanostructure, 1 part by weight is more preferably included with respect to 100 parts by weight of the foamable polyurethane raw material, on the extension of the technical significance described above. In the same context, the carbon nanostructure is graphene, and it is more preferable to include 3 parts by weight based on 100 parts by weight of the foamable polyurethane raw material.

On the other hand, the foamable polyurethane raw material of the present invention may include various types of additional materials in addition to the above-mentioned components. Catalysts, blowing agents, additional cell openers, surfactants, crosslinking agents, chain extenders, colorants, antistatic agents, preservatives, neutralizing agents, antioxidants and the like can be considered as examples of additional materials.

For example, a blowing agent is required to prepare the polyurethane foam used in the sound absorbing material for the acoustic chamber of the present invention, and a preferred example of the blowing agent is water in that it can dissolve the components included in the foamed composition of the present invention. .

However, when the amount of water is not sufficient to obtain the desired density of the foam by other known methods for producing polyurethane foams, methods of introducing reduced pressure or pressurized conditions, air, gases such as _{N 2} and CO _{2 are used.} method, using conventional blowing agents such as chlorofluorocarbons, hydrofluorocarbons, hydrocarbons and fluorocarbons, other reactive blowing agents, i.e. reacting with any component in the reaction mixture and resulting Additional considerations include the use of a gas-releasing agent that foams the mixture, the use of a catalyst that promotes a reaction that induces gas formation, such as the use of a carbodiimide-forming-promoting catalyst such as phospholene oxide. there is. It is also permissible to combine one or more of the above methods. The amount of the blowing agent may vary greatly, but it is preferable to include 1 to 15 parts by weight, more specifically 1 to 12 parts by weight, based on 100 parts by weight of the polyol.

On the other hand, the foam composition of the present invention may further include one or more catalysts. Illustrative of suitable catalysts are at least one amine catalyst selected from the group consisting of a primary amine catalyst, a secondary amine catalyst, and a tertiary amine catalyst.

Non-limiting examples of amine catalysts include trimethylamine, triethylamine, dimethylethanolamine, N-methylmorpholine, N-ethyl-morpholine, N,N-dimethylbenzylamine, N,N-dimethylethanolamine, N ,N,N',N'-tetramethyl-1,4-butanediamine, N,N-dimethylpiperazine, 1,4-diazobicyclo-2,2,2-octane, bis(dimethylaminoethyl)ether , bis(2-dimethylaminoethyl)ether, morpholine, 4,4'-(oxydi2,1-ethanediyl)bis, triethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, N-acetyl N,N-dimethylamine, N-coco-morpholine, N,N-dimethylaminomethyl, N-methylethanolamine, N,N,N'-trimethyl-N'-hydroxyethylbis(aminoethyl ) ether, N,N-bis(3-dimethylaminopropyl)N-isopropanolamine, (N,N-dimethyl)amino-ethoxyethanol, N,N,N',N'-tetramethylhexanediamine, 1, 8-diazabicyclo-5,4,0-undecane-7, N,N-dimorpholinodiethyl ether, N-methylimidazole, dimethylaminopropyldipropanolamine, bis(dimethylaminopropyl)amino- 2-propanol, tetramethylaminobis(propylamine), dimethyl(aminoethoxyethyl)dimethylamineethylether, tris(dimethyl-aminopropyl)amine, dicyclohexylmethylamine, bis(N,N-dimethyl-3- aminopropyl)amine, 1,2-ethylenepiperidine, and methyl-hydroxyethylpiperazine can be considered.

On the other hand, the present specification additionally discloses a sound absorbing material for a sound absorbing material manufactured by using any one of the sound absorbing foam composition for the sound absorbing material of the present invention. As will be described later, the sound-absorbing material for an acoustic chamber of the present invention is characterized in that flame retardancy is further added compared to the conventional sound-absorbing material for an acoustic chamber, and exhibits improved sound-absorbing properties.

The sound absorbing material for an acoustic chamber of the present invention may be used alone or may be used in a manner in which additional lamination is made on one or both surfaces thereof. The additional lamination may be performed for the purpose of further imparting a sense of aesthetics, further improving sound absorption, further enhancing impact resistance, or further enhancing corrosion resistance. For example, as a material that can be used in parallel with the sound-absorbing material for an acoustic chamber of the present invention, a water-repellent nonwoven fabric, a CPP film, an LLPDE film, and the like may be considered.

{Examples and Evaluation}

Hereinafter, with reference to embodiments will be described in more detail with respect to what the present specification claims. However, the embodiments presented in the present specification may be modified in various ways by those skilled in the art to have various forms, and the description of the present specification is not intended to limit the present invention to a specific disclosed form, but the present invention It should be regarded as including all equivalents or substitutes included in the spirit and scope of the present invention.

Examples 1 to 4. Sound absorbing material for acoustic chamber containing N10

에서 1분 동안 가열하고 상온에서 약 10 MPa의 압력으로 압축하여 본 발명의 음향실용 흡음재를 제조하였다. According to the composition of Table 1 below, as methylene diphenyl diisocyanate (MDI, Methylene diphenyl diisocyanate), polypropylene glycol (PPG, Polypropylene glycol), and thermoplastic resin powder in a mixer, polypropylene having an average particle diameter of about 30 μm ( PP, polypropylene) powder and nylon-6,10 resin powder (N10) with an average particle diameter of about 30㎛, boric acid (BA, Boric acid), and carbon black (CB, Carbon Black) are mixed, and water is used as a blowing agent. was added to prepare a foam sheet (thickness 150 mm). 200 before molding the foam sheet

A sound absorbing material for an acoustic chamber of the present invention was prepared by heating for 1 minute at room temperature and compression at a pressure of about 10 MPa at room temperature.

Examples 5 to 8. Sound absorbing material for acoustic chamber containing PVC

에서 1분 동안 가열하고 상온에서 약 10 MPa의 압력으로 압축하여 본 발명의 음향실용 흡음재를 제조하였다. According to the composition of Table 1 below, as methylene diphenyl diisocyanate (MDI, Methylene diphenyl diisocyanate), polypropylene glycol (PPG, Polypropylene glycol), and thermoplastic resin powder in a mixer, polypropylene having an average particle diameter of about 30 μm ( PP, polypropylene) powder and polyvinyl chloride resin powder (PVC) having an average particle diameter of about 30㎛, boric acid (BA, Boric acid), and carbon black (CB, Carbon Black) are mixed, and water is added as a blowing agent. to prepare a foam sheet (thickness 150 mm). 180 before molding the foam sheet

A sound absorbing material for an acoustic chamber of the present invention was prepared by heating for 1 minute at room temperature and compression at a pressure of about 10 MPa at room temperature.

Examples 9 to 12. Sound absorbing material for acoustic chamber comprising N10 and PVC

에서 1분 동안 가열하고 상온에서 약 10 MPa의 압력으로 압축하여 본 발명의 음향실용 흡음재를 제조하였다. According to the composition of Table 1 below, methylene diphenyl diisocyanate (MDI, Methylene diphenyl diisocyanate) and polypropylene glycol (PPG, Polypropylene glycol) were used as foamable polyurethane raw materials in a mixer, and the average particle diameter was about 30 μm. Polypropylene (PP, polypropylene) powder, nylon-6,10 resin powder (N10) with an average particle diameter of about 30 μm, and polyvinyl chloride resin powder (PVC) with an average particle diameter of about 30 μm were added as thermoplastic resin powder. , boric acid (BA, Boric acid), and carbon black (CB, Carbon Black) were mixed, and water as a blowing agent was added thereto to prepare a foam sheet (thickness 150 mm). About 210 prior to molding the foam sheet

A sound absorbing material for an acoustic chamber of the present invention was prepared by heating for 1 minute at room temperature and compression at a pressure of about 10 MPa at room temperature.

* PPG MDI PP N10 BA CB Water Example 1 49 51 10 15 10 One One Example 2 50 50 10 23 10 One One Example 3 48 52 10 15 15 One One Example 4 50 50 10 11 10 One One PPG MDI PP PVC BA CB Water Example 5 50 50 10 10 5 One One Example 6 49 51 10 14 5 One One Example 7 50 50 10 9 4 One One Example 8 50 50 10 5 5 One One PPG MDI PP N10 PVC BA CB Water Example 9 50 50 10 10 10 10 One One Example 10 49 51 10 14 5 10 One One Example 11 50 50 10 10 4 10 One One Example 12 50 50 10 5 9 10 One One

* The above figures are approximate calculations of relative weight parts.

Comparative Examples 1 to 5. Sound absorbing material comprising N10 and/or PVC

에서 1분 동안 가열하고 상온에서 약 10 MPa의 압력으로 압축하여 본 발명의 음향실용 흡음재를 제조하였다. According to the composition of Table 1 below, methylene diphenyl diisocyanate (MDI, Methylene diphenyl diisocyanate) and polypropylene glycol (PPG, Polypropylene glycol) were used as foamable polyurethane raw materials in a mixer, and the average particle diameter was about 30 μm. Polypropylene (PP, polypropylene) powder, nylon-6,10 resin powder (N10) with an average particle diameter of about 30 μm, and polyvinyl chloride resin powder (PVC) with an average particle diameter of about 30 μm were added as thermoplastic resin powder. , boric acid (BA, Boric acid), and carbon black (CB, Carbon Black) were mixed, and water as a blowing agent was added thereto to prepare a foam sheet (thickness 150 mm). About 210 prior to molding the foam sheet

A sound absorbing material for an acoustic chamber of the present invention was prepared by heating for 1 minute at room temperature and compression at a pressure of about 10 MPa at room temperature.

* PPG MDI PP N10 PVC BA CB Water Comparative Example 1 50 50 10 5 - 10 One One Comparative Example 2 49 51 10 - - 10 One One Comparative Example 3 50 50 10 10 - 20 One One Comparative Example 4 50 50 - 10 5 - One One Comparative Example 5 50 50 10 10 5 - - One

* The above figures are approximate calculations of relative weight parts.

Evaluation 1. Evaluation of physical properties of Examples and Comparative Examples

Each of the sound absorbing material specimens of Examples 1 to 12 and Comparative Examples 1 to 5 was collected, and the physical properties of each specimen were measured. The evaluation results are shown in Table 3 below. The evaluation items are density and hardness, and each evaluation criterion is in accordance with JIS K-6301 and KS M 6784. In detail, the evaluation of hardness is a value corresponding to the median of five hardness measurements with a type E durometer hardness machine.

Evaluation items Evaluation items Evaluation target Density (kg/m ² ) Hardness Evaluation target density Hardness Example 1 39 51 Example 9 41 53 Example 2 42 48 Example 10 41 49 Example 3 40 49 Example 11 39 51 Example 4 37 48 Example 12 36 52 density Hardness density Hardness Example 5 38 53 Comparative Example 1 47 38 Example 6 40 58 Comparative Example 2 49 34 Example 7 39 53 Comparative Example 3 48 33 Example 8 37 52 Comparative Example 4 43 31 - Comparative Example 5 41 35

Referring to Table 3, it was confirmed that the sound absorbing materials for acoustic chambers corresponding to Examples 1 to 12 of the present invention generally had a lower density and greater hardness than the sound absorbing materials of Comparative Examples 1 to 5. Referring to the evaluation results of Examples 1 to 12 and Comparative Examples 1 to 5, when the hardness of the sound absorbing material is determined, the type and content of the thermoplastic resin powder, whether or not boric acid is added and the content, and whether or not the carbon nanostructure is added are complex. appeared to work. In particular, it was evaluated that whether PVC, BA, and CB were added and their content was an important factor in determining hardness.

Evaluation 2. Evaluation of sound absorption of Examples and Comparative Examples

An additional experiment was conducted to evaluate the sound absorption of the sound-absorbing material for an acoustic chamber of the present invention. The evaluation objects were the specimens of Examples 1, 6, 11, and 12, and Comparative Examples 4 and 5. The composition of the specimen is summarized in Table 4 below.

PPG MDI PP N10 PVC BA CB Water Example 1 50 50 10 15 - 10 One One Example 6 50 50 10 - 14 5 One One Example 11 50 50 10 10 4 10 One One Example 12 50 50 10 5 9 10 One One PPG MDI PP N10 PVC BA CB Water Comparative Example 4 50 50 - 10 5 - One One Comparative Example 5 50 50 10 10 5 - - One

The sound absorption properties of each specimen were evaluated based on the sound absorption coefficient obtained by comparing the sound pressures of the incident wave and the reflected wave. The sound absorption rate was investigated by the in-pipe method, and the sound absorption tester of Daehan Solution was used. The sound absorption coefficient is 1 when the sound pressure of the reflected wave is 0, and 0 when the sound pressure of the reflected wave is equal to the sound pressure of the incident wave.

In both of the specimens of Examples and Comparative Examples, gentle linearity was confirmed between the Hz of the incident wave and the sound rate up to about 1,500 Hz. However, in the specimens of Comparative Examples 4 and 5, the maximum point was about 1,500 Hz, and it was found that the sound absorption coefficient converges to 0.6 or less at 1,500 Hz or more. On the other hand, in the case of Examples 1, 6, 11, and 12, the maximum point appeared at 1,800 Hz or more, and the sound absorption rate at the maximum point was also larger than that of the comparative example. In addition, it was found to have a sound absorption coefficient of 0.75 or more even at Hz of 2,000 Hz or more. The experimental results are summarized in Table 5 below. According to the evaluation result, in the case of Example 11, it was confirmed that it had especially outstanding sound absorption.

Example 1 Example 6 Example 11 Example 12 Comparative Example 4 Comparative Example 5 maximum point ^* 2,000 2,200 2,050 2,000 1,500 1,450 Absorption rate ^** 0.88 0.91 0.95 0.85 0.64 0.58

* Unit is Hz.

** Round off values to two decimal places

Evaluation 3. Flame-retardant evaluation of Examples and Comparative Examples

An additional experiment was conducted to evaluate the flame retardancy of the sound-absorbing material for an acoustic chamber of the present invention. The evaluation target is the same as in evaluation 2. The flame retardancy was evaluated through thermogravimetric analysis (TGA). The decomposition temperature of each specimen is shown in Table 6 below. Referring to Table 6, it can be seen that polyvinyl chloride, nylon-6,10, and boric acid are all included in the sound-absorbing material for an acoustic chamber of the present invention, and thus, in particular, the flame retardancy is improved. On the other hand, according to the evaluation results of Examples 1 and 6, it is also worth paying attention to the additional improvement of the flame retardancy that can be enjoyed by including both polyvinyl chloride and boric acid.

On the other hand, in the case of Example 11, it was confirmed that the decomposition temperature was formed at a relatively high point even though it contained a relatively small amount of polyvinyl chloride. It is considered that nylon-6,10 achieves uniform dispersion of boric acid and suppresses radical reaction by polyvinyl chloride, thereby enjoying additional advantages.

Example 1 Example 6 Example 11 Example 12 Comparative Example 4 Comparative Example 5 Decomposition temperature (℃) 194 212 209 213 161 158

Claims (7)

foamed polyurethane raw materials; thermoplastic resin powder; As a foamed composition for sound absorbing material formed by mixing boric acid and carbon nanostructures and having improved flame retardancy and sound absorption,
Based on 100 parts by weight of the foamable polyurethane raw material, 10 parts by weight of polypropylene, 10 parts by weight of nylon-6,10 resin powder, and 4 parts by weight of polyvinyl chloride resin powder are included as the thermoplastic resin powder,
The boric acid is included in 10 parts by weight,
As the carbon nanostructure, 1 part by weight of carbon black is included, a foamed composition for a sound absorbing material.
delete delete delete delete delete A sound absorbing material for an acoustic chamber, manufactured using the foam composition for the sound absorbing material of claim 1 .