KR20230096676A - Expandable resin composition, method for preparing the same and foamed molded article produced therefrom - Google Patents

Abstract

The foamable resin composition of the present invention includes 100 parts by weight of a polypropylene resin; 30 to 130 parts by weight of a polyolefin-based elastomer; and 2 to 14 parts by weight of carbon black; and a foamable resin composition in the form of foamed particles in which the foaming ratio is 30 to 80 times and the average cell size is 150 to 350 μm. It is characterized in that the measured density is 10 to 40 g/L, and the dynamic modulus measured according to KS F 2868 is 10 to 20 MN/m ³ . The foamable resin composition has excellent heat insulation properties, heat resistance, sound insulation properties, appearance characteristics, and the like.

Description

Expandable resin composition, manufacturing method thereof, and expanded molded article produced therefrom

The present invention relates to a foamable resin composition, a method for preparing the same, and an expanded molded article prepared therefrom. More specifically, the present invention relates to a foamable resin composition having excellent thermal insulation properties, heat resistance, sound insulation properties, appearance properties, and the like, a manufacturing method thereof, and an expanded molded article manufactured therefrom.

An expandable resin composition in the form of expanded particles can be prepared by introducing the foamable resin composition together with water into a high-pressure reactor, utilizing carbon dioxide gas, etc. as a foaming agent and discharging under reduced pressure at a constant temperature and pressure condition, and manufacturing the foamed particles into a mold. It can be filled in, heated and fused to produce a molded article (foam molded article). Molded articles manufactured in this way have excellent stiffness, light weight, buffering properties, waterproofness, heat retention, and heat insulation, and are used in various fields such as packaging materials for home appliances, boxes for agricultural and marine products, riches, and insulation materials for building materials.

Among them, in relation to floor impact sound regulation in the field of construction, a problem of discrepancy between certificate marking and field performance (difference with field performance: 60%, 2019 Board of Audit and Inspection) has been reported. Results were reported that were satisfactory for light impacts but unsatisfactory for heavy impacts. As a result, after 2022, the regulation of floor impact sound will change from a pre-approval system to a post-evaluation system, and from July 2022, performance tests will be conducted at the site before completion. However, there is a problem that it is difficult to pass field performance tests with existing materials.

Therefore, it is necessary to develop a foamable resin composition having excellent thermal insulation properties and sound insulation properties (blocking light impact sound and heavy impact sound).

The background art of the present invention is disclosed in Korean Patent Publication No. 10-2009-0121088 and the like.

An object of the present invention is to provide a foamable resin composition having excellent heat insulation properties, heat resistance, sound insulation properties, appearance properties, and the like.

Another object of the present invention is to provide a method for preparing the foamable resin composition.

Another object of the present invention is to provide a foam molded article formed from the foamable resin composition.

The above and other objects of the present invention can all be achieved by the present invention described below.

1. One aspect of the present invention relates to a foamable resin composition. The foamable resin composition includes 100 parts by weight of a polypropylene resin; 30 to 130 parts by weight of a polyolefin-based elastomer; and 2 to 14 parts by weight of carbon black; and a foamable resin composition in the form of foamed particles in which the foaming ratio is 30 to 80 times and the average cell size is 150 to 350 μm. It is characterized in that the measured density is 10 to 40 g/L, and the dynamic modulus measured according to KS F 2868 is 10 to 20 MN/m ³ .

2. In the first embodiment, the polypropylene resin may include at least one of a propylene homopolymer, a propylene-ethylene random copolymer, and an ethylene-propylene copolymer.

3. In the embodiment 1 or 2, the polyolefin-based elastomer may include at least one of ethylene-octene rubber, ethylene-propylene rubber, ethylene-butene rubber, and ethylene propylene diene monomer rubber.

4. In the above 1 to 3 embodiments, the weight ratio of the polyolefin-based elastomer and the carbon black may be 1:0.03 to 1:0.3.

5. Another aspect of the present invention relates to a method for preparing a foamable resin composition. The preparation method comprises preparing a mixture by mixing a dispersion medium containing water and a dispersing agent with a resin composition containing 100 parts by weight of a polypropylene resin, 30 to 130 parts by weight of a polyolefin elastomer, and 2 to 14 parts by weight of carbon black; And adding a foaming agent to the mixture, and foaming so that the foaming ratio is 30 to 80 times and the average cell size is 150 to 350 μm, and the density measured according to ISO 845 is 10 to 40 g / L And, it is characterized in that the dynamic elastic modulus measured in accordance with KS F 2868 is 10 to 20 MN / m ³ .

6. In the above 5 embodiments, the foaming is performed by heating and pressurizing the mixture into which the foaming agent is added to a temperature condition of 130 to 160 ° C and a pressure condition of 20 to 60 kgf / cm ² , and then exposing to room temperature and atmospheric pressure conditions can

7. Another aspect of the present invention relates to an expanded molded article. The foam molded article is characterized in that it is formed by filling a mold with the foamable resin composition according to any one of 1 to 4, heating and fusing it.

8. In the 7 specific examples, the foamed molded article may have a thermal conductivity of 0.030 to 0.038 W/m·K, measured according to ISO 8301.

9. In the 7 embodiments, the foam molded article may have a heat deflection temperature (HDT) of 68 to 80 °C, measured under conditions of a load of 18.5 kgf/cm ² and a heating rate of 120 °C/hr in accordance with ASTM D648.

10. In the 7 embodiments, the foam molded article may have a weight impact sound difference of 1 to 6 dB calculated according to Equation 1 below:

[Equation 1]

Weight impact sound difference = weight impact sound for basic slab - weight impact sound after adding foam molding

In Equation 1, the weight impact sound for the basic slab is the impact sound measured by impacting a basic slab with a thickness of 210 mm with a bang machine according to KS F 2863-2, and the weight impact sound after adding the foam molded body is KS F 2863- Based on 2, the impact sound was measured by installing a 40 mm thick foam molding (buffer material) and 70 mm finishing mortar on the slab in order, and then impacting them with a bang machine.

The present invention has the effect of the invention to provide a foamable resin composition excellent in heat insulation, heat resistance, sound insulation, appearance characteristics, etc., a manufacturing method thereof, and an expanded molded article manufactured therefrom.

Hereinafter, the present invention will be described in detail as follows.

A foamable resin composition according to the present invention comprises (A) a polypropylene resin; (B) a polyolefin-based elastomer; and (C) carbon black.

In this specification, "a to b" representing a numerical range is defined as "≥a and ≤b".

(A) polypropylene resin

A polypropylene resin according to one embodiment of the present invention is a base resin for forming a foamable resin composition and an expanded molded article, and includes a propylene homopolymer; propylene-ethylene random copolymers; an ethylene-propylene copolymer obtained by stepwise polymerization of a propylene homopolymerization portion and an ethylene-propylene copolymerization portion in a reactor; or combinations thereof. For example, propylene-ethylene random copolymers can be used.

In an embodiment, the polypropylene resin has a melt-flow index of 1 to 50 g/10 min, for example 5 to 30 g, measured under a load condition of 230° C. and 2.16 kg, according to ASTM D1238. /may be 10 minutes. Within the above range, the foamable resin composition may have excellent mechanical strength, molding processability, foamability, and the like.

(B) polyolefin elastomer

The polyolefin-based elastomer according to one embodiment of the present invention is applied to a polypropylene resin together with carbon black to improve heat insulation, sound insulation, impact resistance, etc. Polyolefin-based elastomers used in the polyolefin foamable resin composition of can be used.

In specific embodiments, ethylene-octene rubber, ethylene-propylene rubber, ethylene-butene rubber, ethylene propylene diene monomer rubber, combinations thereof, and the like may be used as the polyolefin-based elastomer. Preferably, ethylene-octene rubber may be used.

In embodiments, the polyolefin-based elastomer may have an ethylene content of 10 to 60% by weight, for example, 15 to 50% by weight, as measured using an IR analyzer. Within this range, compatibility and bonding strength with components may be excellent, and impact resistance and sound insulation properties of the expandable resin composition and the foam molded article may be excellent.

In embodiments, the polyolefin-based elastomer may be included in an amount of 30 to 130 parts by weight, for example, 40 to 120 parts by weight, specifically 44 to 115 parts by weight, based on 100 parts by weight of the polypropylene resin. When the content of the polyolefin-based elastomer is less than 30 parts by weight based on 100 parts by weight of the polypropylene resin, there is a risk of deterioration in sound insulation and impact resistance of the foamable resin composition and the foam molded article, and when it exceeds 130 parts by weight, There is a possibility that the heat resistance, compressive strength, etc. of the foamable resin composition and the molded foam article may decrease.

(C) carbon black

Carbon black according to one embodiment of the present invention can be applied to a polypropylene resin together with a polyolefin-based elastomer to improve heat insulation, sound insulation, impact resistance, etc. As such, carbon black applied to conventional foamable resin compositions can be used.

In embodiments, the carbon black may have a surface area of 20 to 60 m ² /g, for example, 30 to 50 m ² /g, as measured by the Nitrogen surface area ASTM D6556 method. Within the above range, the foamable resin composition and the foam molded article may have excellent thermal insulation properties.

In embodiments, the carbon black may be included in an amount of 2 to 14 parts by weight, for example, 2.5 to 13.8 parts by weight, based on 100 parts by weight of the polypropylene resin. If the content of the carbon black is less than 2 parts by weight based on 100 parts by weight of the polypropylene resin, there is a risk of deterioration in thermal insulation properties of the foamable resin composition and the foamed molded article, and if it exceeds 14 parts by weight, the foamable resin composition and foaming There is a possibility that the foamability, moldability (processability), external appearance characteristics (voids), stiffness (tensile strength), and the like of the molded article may be deteriorated.

In an embodiment, the weight ratio of the polyolefin-based elastomer and the carbon black may be 1:0.03 to 1:0.3, for example, 1:0.03 to 1:0.25. Within the above range, heat insulation, heat resistance, sound insulation, balance of physical properties, and the like of the foamable composition and the foamed molded article may be more excellent.

The foamable resin composition according to one embodiment of the present invention has an expansion ratio of 30 to 80 times and an average cell size of 150 to 350 μm in the resin composition including the polypropylene resin, polyolefin-based elastomer, and carbon black. It is in the form of expanded particles prepared by foaming as much as possible.

In embodiments, the resin composition may be in the form of pellets obtained by mixing the components and melt-extruding them at 150 to 240° C., for example, 160 to 230° C., using a conventional single-screw or twin-screw extruder.

In embodiments, the expandable resin composition (expanded particles) may have an expansion ratio of 30 to 80 times, for example, 40 to 60 times, and an average cell size of 150 to 350 μm, for example, 150 to 300 μm. there is. Within the above range, foam moldability (adhesion property) and mechanical properties of the expanded particles (expandable resin composition) may be excellent. Here, the foaming ratio of the foamed particles can be measured by a direct immersion method, and in detail, the density of the foamed particles is calculated by measuring the weight and volume of the dried foamed particles using a measuring cylinder and a scale, and then the resin composition before foaming. It is a value converted by taking the particle density of 0.9 g/cm ³ as a standard 1 time, and the average size of the cell is obtained by cutting the cross section after cooling the expanded particle with liquid nitrogen, and using a scanning electron microscope (SEM) to determine the cell size of the expanded particle. It is a value obtained by measuring 10 or more diameters (sizes) and then calculating the average value.

In embodiments, the expandable resin composition (expanded particles) may have a density of 10 to 40 g/L, for example, 10 to 30 g/L, as measured according to ISO 845. If it is out of the above range, there is a concern that the lightness, heat insulation, mechanical properties, etc. of the foamable resin composition and the foamed molded article may be deteriorated.

In a specific embodiment, the expandable resin composition (expanded particles) may have a dynamic modulus of 10 to 20 MN/m ³ , for example, 14 to 19 MN/m ³ measured according to KS F 2868. If it is out of the above range, there is a concern that sound insulation and mechanical properties (tensile strength, compressive strength, etc.) of the foamable resin composition and the molded foam article may deteriorate.

The foamable resin composition according to one embodiment of the present invention may further include additives used in conventional foamable resin compositions within a range that does not impair the objects and effects of the present invention. Examples of the additive include antioxidants, light stabilizers, heat stabilizers, flame retardants, colorants, plasticizers, slip agents, combinations thereof, and the like, but are not limited thereto. When using the additive, the content thereof may be 0.001 to 40 parts by weight, for example, 0.1 to 10 parts by weight, based on 100 parts by weight of the polypropylene resin.

The expandable resin composition according to one embodiment of the present invention may be prepared according to a known method for preparing expanded particles. For example, preparing a mixture by mixing the resin composition with a dispersion medium containing water and a dispersant; In addition, a foaming agent may be added to the mixture and foamed to have the foaming ratio and the average cell size.

In embodiments, the dispersant may include one or more of higher fatty acids, higher fatty acid esters, and higher fatty acid amides.

In an embodiment, the resin composition may be introduced into a reactor in which a dispersion medium is present, or a dispersion medium may be introduced into a reactor together with the resin composition to form a mixture.

In a specific embodiment, the blowing agent may be a blowing agent used for conventional foaming particles, for example, carbon dioxide, propane, butane, hexane, pentane, heptane, cyclobutane, cyclohexane, methyl chloride, ethyl chloride, methylene Chloride, dimethyl ether, diethyl ether, methyl ethyl ether, nitrogen, argon, etc. may be used alone or in combination of two or more.

In embodiments, the foaming is performed by mixing the mixture into which the blowing agent is introduced at a temperature condition of 130 to 160°C, for example, 135 to 155°C, and a pressure condition of 20 to 60 kgf/cm ² , for example, 30 to 50 kgf/cm ² . After heating and pressurizing to be, it may be performed by exposure to room temperature and atmospheric pressure conditions. Under the above temperature and pressure conditions, foam particles (expandable resin composition) having an expansion ratio of 30 to 80 times, for example 40 to 60 times, and an average cell size of 150 to 350 μm, for example 150 to 300 μm are obtained. can

In a specific embodiment, the expanded particles (expandable resin composition) may have an average particle diameter of 1 to 7 mm, for example, 2 to 6 mm, as measured by a vernier caliper, but is not limited thereto. Within this range, foam moldability and the like may be excellent.

The foam molded article according to the present invention can be formed by filling and fusing the expandable resin composition (foam particles) into a mold, and can be easily manufactured by those skilled in the art. For example, the expanded molded article is formed by filling (introducing) the expanded particles into a non-airtight mold, and supplying saturated steam (eg, saturated steam at a pressure of 2.0 to 3.5 bar) to the mold for about 30 seconds, It may be prepared by fusing the expanded particles with each other and drying them.

In a specific embodiment, the foam molded article may have a thermal conductivity of 0.030 to 0.038 W/m·K, for example, 0.031 to 0.036 W/m·K, as measured according to ISO 8301.

In one embodiment, the foam molded article has a heat deflection temperature (HDT) of 68 to 80 °C, for example, 70 to 78 °C, measured under conditions of a load of 18.5 kgf/cm ² and a heating rate of 120 °C/hr in accordance with ASTM D648. can be

In a specific embodiment, the foam molded article may have a weight impact sound difference of 1 to 6 dB, for example, 1 to 4 dB, calculated according to Equation 1 below.

[Equation 1]

Weight impact sound difference = weight impact sound for basic slab - weight impact sound after adding foam molding

In Equation 1, the weight impact sound for the basic slab is the impact sound measured by impacting a basic slab with a thickness of 210 mm with a bang machine according to KS F 2863-2, and the weight impact sound after adding the foam molded body is KS F 2863- Based on 2, the impact sound was measured by installing a 40 mm thick foam molding (buffer material) and 70 mm finishing mortar on the slab in order, and then impacting them with a bang machine.

In a specific embodiment, the foam molded article is useful as an interlayer sound insulation material for construction because it has excellent thermal insulation properties, heat resistance, sound insulation properties, and exterior properties.

Hereinafter, the present invention will be described in more detail through examples, but these examples are only for the purpose of explanation and should not be construed as limiting the present invention.

Example

Hereinafter, specifications of each component used in Examples and Comparative Examples are as follows.

(A) polypropylene resin

A propylene-ethylene random copolymer (manufacturer: Lotte Chemical, product name: SEP-550) was used.

(B) polyolefin elastomer

Ethylene-octene rubber (manufacturer: Lotte Chemical, product name: LEO0310) was used.

(C) carbon black

Carbon black (manufacturer: Orion, product name: HIBLACK®20L, surface area: 88 m ² /g) was used.

Examples 1 to 6 and Comparative Examples 1 to 5

After adding each of the above constituents in an amount as shown in Tables 1 and 2 below, a resin composition (1.2 mg, Φ 0.8 mm × 1.1 mm in pellet form) was prepared by extrusion at 220 ° C. For extrusion, a single screw extruder (screw rotational speed: 700 rpm) with L/D = 34 and a diameter of 40 mm was used. Then, 100 parts by weight of the resin composition was put into an autoclave together with 300 parts by weight of a dispersion medium (water to which a dispersant was added). After adding carbon dioxide (CO ₂ ) as a foaming agent to the autoclave, the temperature and pressure inside the autoclave were adjusted to 140 to 150° C. and 40 kg/cm ² while stirring. Next, the contents of the autoclave were exposed to the atmosphere to prepare expanded particles (expandable resin composition, expansion ratio: 40 times). After drying the expanded particles at room temperature for 24 hours, they were put in a pressure tank and pressurized from atmospheric pressure (1 bar) to 3 bar over 10 hours, and then filled into a mold (450 mm × 450 mm × 50 mm). Thereafter, saturated steam of 2.5 bar was supplied to the mold for 30 seconds, and the expanded particles were fused together, cooled, and then dried in a convection oven at 70° C. for 12 hours to prepare an expanded molded article. For the manufactured foam molded article, physical properties were evaluated by the following method, and the results are shown in Tables 1 and 2 below.

How to measure physical properties

(1) Average cell size: A specimen of foamed particles (expandable resin composition) expanded so that the expansion ratio is 40 times cooled with liquid nitrogen, and then the cross section is cut, 10 cells are randomly selected, and each cell diameter ( size) was measured using a scanning electron microscope (SEM), and then the average value of the cell diameter (average size, unit: μm) was calculated.

(2) Density (unit: g/L): According to ISO 845, the density of the expanded particle specimen was measured.

(3) Dynamic modulus of elasticity (Unit: MN/m ³ ): In accordance with KS F 2868, the dynamic modulus of elasticity of the expanded particle specimens was measured.

(4) Thermal conductivity (unit: W/m K): According to ISO 8301, the thermal conductivity of the molded foam specimen was measured.

(5) Heat deflection temperature (unit: °C): Heat deflection temperature (HDT) was measured under the conditions of a load of 18.56 kgf/cm ² and a heating rate of 120 °C/hr in accordance with ASTM D648.

(6) Weight impact sound difference (unit: dB): The weight impact sound difference was calculated according to Equation 1 below.

[Equation 1]

Weight impact sound difference = weight impact sound for basic slab - weight impact sound after adding foam molding

In Equation 1, the weight impact sound for the basic slab is the impact sound measured by impacting a basic slab having a thickness of 210 mm with a bang machine (impacting a 7.3 kg tire at a height of 85 cm) in accordance with KS F 2863-2, The weight impact sound after adding the foam molded body is measured according to KS F 2863-2 by installing a foam molded body (buffer material) with a thickness of 40 mm and a finishing mortar of 70 mm in order on the slab, and then impacting them with a bang machine. Here, when the impact sound difference is negative (-), it means that the noise (impact sound) is amplified.

Example One 2 3 4 5 6 (A) (parts by weight) 100 100 100 100 100 100 (B) (parts by weight) 44.1 46.9 69 74.1 104.2 113.6 (C) (parts by weight) 2.9 9.4 3.4 11.1 4.2 13.6 Average cell size (μm) 220 150 250 150 250 150 Density (g/L) 17 17 17 17 17 17 Dynamic modulus of elasticity (MN/m ³ ) 17 19 16 18 15 17 Thermal conductivity (W/m K) 0.036 0.031 0.036 0.031 0.036 0.031 Heat deflection temperature (℃) 72 74 72 76 70 71 Weight Impact Sound Difference (dB) 2 One 3 2 3 2

comparative example One 2 3 4 5 (A) (parts by weight) 100 100 100 100 100 (B) (parts by weight) 26.3 166.7 67.8 110 75.5 (C) (parts by weight) 5.3 11.1 1.7 15 13.2 Average cell size (μm) 170 250 250 100 130 Density (g/L) 17 17 17 17 17 Dynamic modulus of elasticity (MN/m ³ ) 25 13 16 19 18 Thermal conductivity (W/m K) 0.035 0.035 0.040 0.031 0.030 Heat deflection temperature (℃) 77 62 72 73 73 Weight Impact Sound Difference (dB) -2 0 3 2 2

From the above results, the expandable resin composition (expanded particles) of the present invention can form an expanded molded article having excellent cell quality, heat insulation (thermal conductivity), heat resistance (heat deflection temperature), and sound insulation (difference in light weight and weight impact sound). know that it can. In addition, since the average cell size is in the range of 150 to 350 μm, it can be seen that the appearance characteristics are excellent.

On the other hand, in the case of Comparative Example 1 using a small amount of the polyolefin-based elastomer, it can be seen that the sound insulation properties, etc. are reduced, and in the case of Comparative Example 2, in which the polyolefin-based elastomer is used in an excessive amount, it can be seen that the heat resistance, sound insulation properties, etc. are reduced, and carbon black In the case of Comparative Example 3, in which a small amount was used, it can be seen that the thermal insulation properties, etc. were lowered, and in the case of Comparative Example 4, in which an excessive amount of carbon black was used, it was found that the appearance properties, etc. were lowered, and the formability (processability), tensile strength, etc. were lowered. confirmed. In addition, even in the case of Comparative Example 5 having an average cell size less than the range of the present invention, it was confirmed that the appearance characteristics and the like were deteriorated, and the formability (processability) and tensile strength were also deteriorated.

So far, the present invention has been looked at mainly through embodiments. Those skilled in the art to which the present invention pertains will be able to understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent scope will be construed as being included in the present invention.

Claims (10)

100 parts by weight of polypropylene resin; 30 to 130 parts by weight of a polyolefin-based elastomer; and 2 to 14 parts by weight of carbon black; an expandable resin composition in the form of expanded particles obtained by foaming a resin composition having a foaming ratio of 30 to 80 times and an average cell size of 150 to 350 μm,
The density measured according to ISO 845 is 10 to 40 g / L,
A foamable resin composition characterized in that the dynamic elastic modulus measured in accordance with KS F 2868 is 10 to 20 MN/m ³ .
The foamable resin composition according to claim 1, wherein the polypropylene includes at least one of a propylene homopolymer, a propylene-ethylene random copolymer, and an ethylene-propylene copolymer.
The foamable resin composition according to claim 1, wherein the polyolefin-based elastomer includes at least one of ethylene-octene rubber, ethylene-propylene rubber, ethylene-butene rubber, and ethylene propylene diene monomer rubber.
The foamable resin composition according to claim 1, wherein the weight ratio of the polyolefin-based elastomer and the carbon black ranges from 1:0.03 to 1:0.3.
A mixture is prepared by mixing a dispersion medium containing water and a dispersing agent with a resin composition containing 100 parts by weight of a polypropylene resin, 30 to 130 parts by weight of a polyolefin elastomer, and 2 to 14 parts by weight of carbon black; and
Adding a foaming agent to the mixture, and foaming the mixture so that the foaming ratio is 30 to 80 times and the average cell size is 150 to 350 μm,
The density measured according to ISO 845 is 10 to 40 g / L,
A method for producing a foamable resin composition, characterized in that the dynamic elastic modulus measured in accordance with KS F 2868 is 10 to 20 MN/m ³ .
The method of claim 5, wherein the foaming is performed by heating and pressurizing the mixture into which the foaming agent is added to a temperature condition of 130 to 160° C. and a pressure condition of 20 to 50 kgf/cm ² , and then exposing to room temperature and atmospheric pressure conditions. Method for producing a foamable resin composition to be.
An expanded molded article characterized in that it is formed by filling a mold with the expandable resin composition according to any one of claims 1 to 4, heating and fusing it.
8. The molded foam article according to claim 7, wherein the molded foam article has a thermal conductivity of 0.030 to 0.038 W/m·K measured according to ISO 8301.
The foamed article according to claim 7, wherein the foamed molded article has a heat deflection temperature (HDT) of 68 to 80 °C measured under conditions of a load of 18.5 kgf/cm ² and a heating rate of 120 °C/hr in accordance with ASTM D648. molded body.
The foam molded article according to claim 7, wherein the foam molded article has a weight impact sound difference of 1 to 6 dB, calculated according to Equation 1 below:
[Equation 1]
Weight impact sound difference = weight impact sound for basic slab - weight impact sound after adding foam molding
In Equation 1, the weight impact sound for the basic slab is the impact sound measured by impacting a basic slab with a thickness of 210 mm with a bang machine according to KS F 2863-2, and the weight impact sound after adding the foam molded body is KS F 2863- Based on 2, the impact sound was measured by installing a 40 mm thick foam molding (buffer material) and 70 mm finishing mortar on the slab in order, and then impacting them with a bang machine.