Sound-absorbing material and method for preparing the same

Abstract

The present invention relates to a sound-absorbing material and a method for preparing the sound-absorbing material. More particularly, the sound-absorbing material, which may be prepared by impregnating a binder into a nonwoven fabric formed of a heat-resistant fiber, is provided. The sound-absorbing may have superior sound-absorbing property, flame retardancy, heat resistance and heat-insulating property, thereby being applicable to parts operating at a temperature of about 200° C. or greater and being shapeable due to the binder. In addition, the method for preparing the sound-absorbing material is provided.

1 . A sound-absorbing material comprising:
 a nonwoven fabric comprising an amount of about 30 wt % to about 100 wt % of a heat-resistant fiber; and   a binder impregnated in the same layer as the nonwoven fabric and maintaining a three-dimensional shape inside the nonwoven fabric.   
     
     
         2 . The sound-absorbing material according to  claim 1 , wherein the heat-resistant fiber has a limiting oxygen index (LOI) of about 25% or greater and a heat resistance temperature in a range of about 150° C. or greater. 
     
     
         3 . The sound-absorbing material according to  claim 2 , wherein the heat-resistant fiber is one or more selected from the group consisting of aramid fiber, polyphenylene sulfide (PPS) fiber, oxidized polyacrylonitrile (oxi-PAN) fiber, polyimide (PI) fiber, polybenzimidazole (PBI) fiber, polybenzoxazole (PBO) fiber, polytetrafluoroethylene (PTFE) fiber, polyketone (PK) fiber, metallic fiber, carbon fiber, glass fiber, basalt fiber, silica fiber and ceramic fiber. 
     
     
         4 . The sound-absorbing material according to  claim 3 , wherein the heat-resistant fiber is an aramid fiber. 
     
     
         5 . The sound-absorbing material according to  claim 1 , wherein the nonwoven fabric is a single-layer nonwoven fabric formed of an aramid fiber having a fineness in a range of about 1 denier to about 15 denier and having a thickness in a range of about 3 mm to about 20 mm. 
     
     
         6 . The sound-absorbing material according to  claim 1 , wherein the nonwoven fabric has a density in a range of about 100 g/m 2  to about 2000 g/m 2 . 
     
     
         7 . The sound-absorbing material according to  claim 5 , wherein the nonwoven fabric has a density in a range of about 200 g/m 2  to about 1200 g/m 2 . 
     
     
         8 . The sound-absorbing material according to  claim 1 , wherein the binder is a thermosetting resin. 
     
     
         9 . The sound-absorbing material according to  claim 8 , wherein the thermosetting resin is an epoxy resin. 
     
     
         10 . The sound-absorbing material according to  claim 9 , wherein the epoxy resin is one or more selected from the group consisting of bisphenol A diglycidyl ether, bisphenol B diglycidyl ether, bisphenol AD diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, polyoxypropylene diglycidyl ether, bisphenol A diglycidyl ether polymer, phosphazene diglycidyl ether, bisphenol A novolac epoxy, phenol novolac epoxy resin and o-cresol novolac epoxy resin. 
     
     
         11 . The sound-absorbing material according to  claim 1 , wherein the sound-absorbing material is shaped to have a three-dimensional shape to which the sound-absorbing material is applied. 
     
     
         12 . The sound-absorbing material according to  claim 1 , wherein the sound-absorbing material is formed in a single layer or multiple layers. 
     
     
         13 . The sound-absorbing material according to  claim 1 , wherein the sound-absorbing material is used in a vehicle. 
     
     
         14 . A method for preparing a sound-absorbing material:
 immersing a nonwoven fabric comprising an amount of about 30 wt % to about 100 wt % of a heat-resistant fiber in a binder solution; and   drying the nonwoven fabric.   
     
     
         15 . The method for preparing the sound-absorbing material according to  claim 14 , further comprises, after said drying the nonwoven fabric, preparing the sound-absorbing material by shaping the dried nonwoven fabric at elevated temperature. 
     
     
         16 . The method for preparing the sound-absorbing material according to  claim 14 , wherein the heat-resistant fiber has a limiting oxygen index (LOI) of about 25% or greater and a heat resistance temperature of about 150° C. or greater. 
     
     
         17 . The method for preparing the sound-absorbing material according to  claim 16 , wherein the heat-resistant fiber is one or more selected from the group consisting of aramid fiber, polyphenylene sulfide (PPS) fiber, oxidized polyacrylonitrile (oxi-PAN) fiber, polyimide (PI) fiber, polybenzimidazole (PBI) fiber, polybenzoxazole (PBO) fiber, polytetrafluoroethylene (PTFE) fiber, polyketone (PK) fiber, metallic fiber, carbon fiber, glass fiber, basalt fiber, silica fiber and ceramic fiber. 
     
     
         18 . The method for preparing the sound-absorbing material according to  claim 14 , wherein the heat-resistant fiber is an aramid fiber having a fineness in a range of about 1 denier to about 15 denier having a yarn length in a range of about 20 mm to about 100 mm. 
     
     
         19 . The method for preparing the sound-absorbing material according to  claim 14 , wherein the nonwoven fabric has a thickness in a range of about 3 mm to about 20 mm and a density in a range of about 100 g/m 2  to about 2000 g/m 2 . 
     
     
         20 . The method for preparing the sound-absorbing material according to  claim 15 , further comprises, before said immersing the nonwoven fabric, forming an aramid nonwoven fabric having a thickness in a range of about 3 mm to about 20 mm by needle punching of a heat-resistant aramid fiber having a fineness in a range of about 1 denier to about 15 denier. 
     
     
         21 . The method for preparing the sound-absorbing material according to  claim 20 , wherein the nonwoven fabric is formed by continuously performing up-down needling, down-up needling and up-down needling. 
     
     
         22 . The method for preparing the sound-absorbing material according to  claim 20 , wherein the nonwoven fabric is formed with a needle stroke in a range of about 30 times/m 2  to about 350 times/m 2 . 
     
     
         23 . The method for preparing the sound-absorbing material according to  claim 14 , wherein the binder solution comprises an amount of about 1 wt % to about 60 wt % of a binder, an amount of about 0.1 wt % to about 10 wt % of a curing agent, an amount of about 0.01 wt % to about 5 wt % of a catalyst, an amount of about 1 wt % to about 40 wt % of an additive and a solvent as the remainder, based on the total weight of the binder solution. 
     
     
         24 . The method for preparing the sound-absorbing material according to  claim 23 , wherein the binder solution comprises an amount of about 1 wt % to about 30 wt % of a binder, an amount of about 0.1 wt % to about 10 wt % of a curing agent, an amount of about 0.01 to about 5 wt % of a catalyst, an amount of about 1 wt % to about 30 wt % of a flame retardant and an amount of about 40 wt to about 95 wt % of a solvent, based on the total of the binder solution. 
     
     
         25 . The method for preparing the sound-absorbing material according to  claim 14 , wherein the binder is a thermosetting resin. 
     
     
         26 . The method for preparing the sound-absorbing material according to  claim 25 , wherein the thermosetting resin is an epoxy resin. 
     
     
         27 . The method for preparing the sound-absorbing material according to  claim 26 , wherein the epoxy resin is one or more selected from the group consisting of bisphenol A diglycidyl ether, bisphenol B diglycidyl ether, bisphenol AD diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, polyoxypropylene diglycidyl ether, bisphenol A diglycidyl ether polymer, phosphazene diglycidyl ether, bisphenol A novolac epoxy, phenol novolac epoxy resin and o-cresol novolac epoxy resin. 
     
     
         28 . The method for preparing a sound-absorbing material according to  claim 14 , wherein the drying is performed at a temperature in a range of about 70° C. to about 200° C. and the dried nonwoven fabric comprises an amount of about 1 part to about 300 parts by weight of a binder based on 100 parts by weight of the nonwoven fabric. 
     
     
         29 . The method for preparing the sound-absorbing material according to  claim 14 , wherein the sound-absorbing material is for an automobile. 
     
     
         30 . A method for reducing noise of a noise-generating device,
 comprising:   i) checking a three-dimensional structure of the noise-generating device;   ii) preparing and shaping a sound-absorbing material of according to  claim 1  in the three-dimensional structure of the device partially or entirely; and   iii) bringing the sound-absorbing material adjacent to the noise-generating device.   
     
     
         31 . The method for reducing noise of the noise-generating device according to  claim 30 , wherein the device is a motor, an engine or an exhaust system. 
     
     
         32 . The method for reducing noise of the noise-generating device according to  claim 30 , wherein the sound-absorbing material is brought adjacent to the noise-generating device by attaching the sound-absorbing material to the noise-generating device, providing the sound-absorbing material with a distance from the noise-generating device, or shaping the sound-absorbing material as a part of the noise-generating device.