GB2282829A

GB2282829A - Sound absorbing member

Info

Publication number: GB2282829A
Application number: GB9419447A
Authority: GB
Inventors: Hirosi Matsukawa; Kyoichi Watanabe; Hiroshi Sugawara
Original assignee: Nissan Motor Co Ltd; Mitsubishi Kasei Corp
Current assignee: Nissan Motor Co Ltd; Mitsubishi Kasei Corp
Priority date: 1993-09-27
Filing date: 1994-09-27
Publication date: 1995-04-19
Anticipated expiration: 2014-09-27
Also published as: JPH0788030A; GB2282829B; GB9419447D0; JPH0817732B2

Abstract

A sound absorbing member comprises a fiber assembly consisting essentially of short fibers and having a thickness of not less than 5 mm, in which new and/or reclaimed polyester fibers are used as the short fibers and not less than 30% by weight of the polyester fibers used have a fiber size of not more than 4 denier. The member may be used in automobiles, eg as a floor insulator or as a dashboard insulator (4). The member is made by hot-pressing the fibres. <IMAGE>

Description

SOUND ABSORBING MEMBER This invention relates to a sound absorbing member comprised of a cheap sound insulation structural body having high performances, and more particularly to a sound absorbing member having improved sound absorbing performance, sound insulating performance, and economical efficiency and a high contribution to social welfare by positively utilizing reclaimed polyethylene terephthalate (PET) materials.

The sound absorbing members according to the invention are particularly suitable as interior sound absorbing members for automobiles, such as floor insulator, dash insulator arranged on a dash panel and the like.

The invention will be described with respect to the dash insulator for the automobile used under severe restricting conditions among the sound absorbing members below. As shown in Fig. 1, the conventional dash insulator 2 locates on a surface of a dash panel 1 dividing an engine room E and a compartment R, and is provided with a sound insulating layer 3 and a sound absorbing layer 4, and serves to prevent transmission of noise from the engine room E to the compartment R.

As shown in Fig. 2, the dash insulator 2 arranged on the dash panel 1 is generally a multilayer structural body of the sound insulating layer 3 having a relatively high density, such as polyvinyl chloride sheet, rubber sheet or the like incorporating a filler therein, and the sound absorbing layer 4 of a porous material, such as felt, polyurethane foam, nonwoven fabric or the like.

In the conventional dash insulator, noise from the engine room E is absorbed by the sound absorbing layer 4, while good soundproof performance is developed by a double sound insulating effect through the dash panel 1 and the sound insulating layer 3.

Recently, it has been confirmed that the sound insulating performance of the dash insulator largely changes in accordance with the adhesion to the dash panel 1. As a result, there are mainly used dash insulators in which a molded sound absorbing member exactly fitting to a surface shape of the dash panel is used as the sound absorbing layer 4. For example f'bsous sour. absorbing werers are ...cru~fact~red by adding a resin binder to chemical fibers or natural fibers and shaping and pressing them under heating. As the resin binder, use may be made of thermoplastic resins such as polyethylene resin, polypropylene resin, polyester resin and the like or thermosetting resins such as phenolic resin and the like.

In this connection, US Patent No. 5,064,714 discloses an internal trim member for automobile in which a fiber assembly in the member is mainly formed by a filling method wherein fibers are blown in a mold together with air. In this method, however, the fibers do not easily come into details of the mold, so that it is required to use thick fibers (6-8 denier) having a relatively heavy weight for attaining complete filling. On the contrary, the use of fine fibers having a size of not more than 4 denier is required for giving high sound absorbing performances to the internal trim member, but these fine fibers are poor in the dispersibility and are unapplicable for the above method because the productivity and the sound absorbing performances can not simultaneously be established. Particularly, not less than 30% by weight of fibers having a size of not more than 4 denier, preferably not more than 2 denier should be included in the internal trim member for satisfying the sound absorbing performances, which is not attained by this method.

In the sound absorbing layer 4 for the conventional dash insulator, felt or the like comprised of natural fibers is mainly used, so that the scattering of fineness is very large to bring about ronWn-formity of sound insulating performance and hence it is difficult to constantly hold such a performance as a product.

Furthermore, the sound absorbing aye has the drawbacks that (i) the sound absorbing performance is poor because a great amount of fibers having a thick denier are existent, (ii) the sound absorbing performance is low in proportion to weight owing to the use of the resin binder, and the like.

Under the above circumstances, it is an object of the invention to provide a sound absorbing member comprised of a light and economical sound insulating structural body in which a fiber assembly is formed from polyester fibers, preferably reclaimed polyester fibers, to provide sound absorbing performances of uniform quality based on the uniform fiber assembly having a regular fiber size.

The use of reclaimed polyester material in the Invention is preferable in view of contribution to social welfare through recycling and economical efficiency. That is, a market of reclaimed PET material is about t0,CUC year it the year Of 599C in aran, which Is aily reused carpet, bedding cotton and the like. However, the full amount of the reclaimed PET material is not always reused and 5,000 t per year thereof is unused at the present.

Recently, the recovery of PET bottles is started and is active socially because the PET bottles have been produced in an amount of 120,000 t per year in the year of 1990 and substantially unused up to the present. The recycle movement of the PET materials becomes more expanded from year to year and will extend to a recovery of 50B in the year 2000.

Moreover, the reclaimed PET material is specified as a second designated product according to a law of utilization promotion of reclaimed sources in 1993, so that the supply of the reclaimed PET material is considered to more increase in future. However, the reuse means of the reclaimed PET material is less at the present, so that the excessive supply can easily be expected in future.

The inventors effectively utilize the reclaimed PET material to develop members having high sound absorbing performances and largely contribute to social welfare by applying such members to automobiles and the like.

According to the invention, there is the provision of a sound absorbing member comprised of a fiber assembly consisting essentially of short fibers and having a thickness of not less than 5 mm, in which polyester fibers (hereinafter referred to as PET fiber) are used as the short fiber and not less than 308 by weight of the PET fiber used have a fiber size of not more than 4 denier.

The invention will be described with reference to the accompanying drawings, wherein: Fig. 1 is a partly sectional fragmentary schematic view illustrating an arrangement of a dash insulator between an engine room and a compartment is an automobile; and Fig. 2 is an enlarged section view of the dash insulator shown in Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS When the sound absorbing member according to the invention is used as a dash insulator for an automobile located on a surface of a dash panel dividing an engine room and a compartment, the fiber assembly in the sound absorbing member is comprised of reclaimed polyester fibers, whereby the sound insulating performance and the economical efficiency are enhanced and the weight is reduced.

The sod ir.suatir.g erforace can ne shown by the easreret of vibration transmissibility and sound absorption coefficient. The vibration transmissibility shous transmission of energy when a body vibrates by the energy. Therefore, the dash insulator is required to have such a performance that vibrations do not transmit from the engine to the compartment. As a result of investigations on the improvement of such a performance by the fiber assembly, it has been confirmed that the performance is largely affected by the formulation of the fibers. The spring constant of the fiber assembly itself largely takes part ifl the vibration transmissibility. That is, the vibration transmissibility can be decreased by reducing the spring constant, whereby the sound insulating performance can be improved.

On the other hand, the spring constant is strongly interrelated to the fineness of the fiber. That is, the fiber assembly comprised of fibers having a fine fiber size has a relatively low spring constant. However, it is technically difficult to reduce the fiber size, which is a factor of increasing the cost from a viewpoint of economical reason and is disadvantageous in the forming step of nonwoven fabric.

From a viewpoint of the performances of the fiber assembly, the fiber size is required to be not more than 4 denier. Considering the balance between the processability and the cost, thick fibers of more than 4 denier are required to be formulated in an amount of 708 by weight at maximum.

In order to obtain most satisfactory sound insulating performance, the spring constant is required to be not more than 80,000 NAT. When the sprig constant exceeds the above value, the degree of transm'ittng vibrations becomes high and the sound insulating performance considerably lowers. As the value of the spring constant becomes small, the sound insulating performance is improved, so that the lower limit is not particularly restricted.

The fiber assembly is required to have a thickness of not less than 5 m. When the thickness is less than 5 mm, the fiber assembly used in the sound absorbing member can not develop satisfactory performances.

The upper limit of the thickness is determined by the weight and economical efficiency, but it is not critical.

Furthermore, the fiber assembly may be formulated with heatfusible fibers having a melting point lower by at least 20CC thar. that of the polyester fiber. As the heat-fusible fiber, use may be made of low- melting point polyester fibber, polyethylene fiber, polypropylene tiber and the like.

An. the fiber assembly according to the 'nven-'o-, the sr.crt fibers having different finenesses may uniformly be dispersed, or the short fibers having the same fineness may locally be gathered to form a bulk or a sheet.

As compared with the fiber assembly of polyester fibers, conventional felt contains about 608 by weight of fibers having a fiber size of not less than 6 denier, so that it can not be said that the felt is effective to reduce the vibration transmissibility.

According to the invention, it is preferable that the intrinsic viscosity of the reclaimed PET material is not less than 0.4 from a viewpoint of the processability at the spinning step. When the intrinsic viscosity is less than 0.4, if the spinning is carried out by using the reclaimed PET material, it is difficult to conduct the spinning due to hanging down of PET melt at dies portion of the spinning apparatus and also yarn breakage is frequently generated and hence it is considerably difficult to form the fiber. On the other hand, the upper limit of the intrinsic viscosity is not particularly restricted.

Furthermore, the reclaimed PET material Dreferably has carboxyl end groups of not more than 100 x 10-6 equivalent/g from a viewpoint of the processability. When the amount of terminal carboxyl end groups exceeds the above value, if the reclaimed PET material is used to form the reclaimed PET fibers in an extrusion spinning machine, melt viscosity is largely decreased due to thermal decomposition and hence it is extremely difficult to conduct the PET melt to the nozzles of an extrusion spinning machine. In addition, yellow coloring is conspicuous in the resulting reclaimed PET fiber to degrade the appearance. Since the sound absorbing member is frequently used in the compartment, the appearance is a large factor in addition to the performances. Under the above circumstance, the upper limit of the carboxyl end groups is determined. On the other hand, the lower limit is not particularly restricted. Although the coloring generated when the amount of carboxyl end groups is within the above value does not come into problem in practical use, it may be avoided from a conspicuous place by using a surface coating member or by using the sound absorbing member in a cor.-ealed location.

In general, it can be said that the sound insulating performance is improved as the sound absorption coefficient becomes high. However, as the density of the fiber assembly is increased, the weight and cost undesirably Increase to degrade the economical efficiency of the sound absorbing member. Furthermore, as the density increases, the vibration transmissibility increases to lower the sound insulating performance. For this end, the density of the fiber assembly is favorable to be not more than 1.5 kg/:r2 considerlro the sound absorption, vibration transnIssibilIty arc weight. Preferably, the density is within a range of 0.6-1.2 kg/m2.

As to the easy production of the fiber assembly, when using short fibers having a fine size, it is difficult to increase the carding rate to form the fiber assemblage at carding machine and a long time is taken for the formation of fiber assembly sheet and hence the efficiency is poor, which is a cause of increasing the cost. Further, the resulting fibers themselves become light and the settlement of the fiber assembly sheet is poor. Therefore, the use of fibers having a thick size becomes good from a viewpoint of the processability. For this purpose, fibers having a relatively thick size of not less than 6 denier is used in an amount of 5 708 by weight, preferably 10-30% by weight in the production of the fiber assembly.

The sound absorbing member according to the invention is applicable to various automobile parts such as dash insulator, floor carpet, head lining and the like and is useful for industrial materials.

According to the invention, industrial sound absorbing members having excellent sound absorbing and insulating performances and processability can be obtained by adjusting the fiber size and suppressing the scattering of fiber size and setting the density to a certain range.

Furthermore, industrial sound absorbing members having high performances and economical efficiency can be provided by using the reclaimed polyester fibers as compared with the conventional members.

The following examples are given in illustration of the invention and are not intended as limitations thereof.

Reference Example 1 Reclaimed PET fibers having a fiber size of 2 denier are stably produced by using reclaimed PET having an intrinsic viscosity of 0.5 and spinning and drawing it at an extrusion temperature of 2700C (drawing temperature: 70or, drawing ratio: 4 times).

Reference Example 2 Reclaimed PET fibers having a fiber size of 3 denier are stably produced by using reclaimed PET having carboxyl end groups of 90 X 10-6 equivalent/g and spinning and drawing it at an extrusion temperature of 2700C (drawing temperature: 700C, drawing ratio: 4 times).

Example 1 A sound absorbing member No. 1 is produced by pressing a fiber :assembly having a density of 0.8 kg/m2 and a size of 300 X 300 X 30 mm, which consists of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 2 A sound absorbing member No. 2 is produced by pressing a fiber assembly having a density of 1.3 kg/m and a size of 300 x 300 x 30 mm, which consists of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 3 A sound absorbing member No. 3 is produced by pressing a fiber assembly having a density of 1.5 kg/m2 and a size of 300 x 300 x 30 mm, which consists of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, under a pressure of 50 kgf/cm2 while heating at 165 C.

Example 4 A sound absorbing member No. 4 is produced by pressing a fiber assembly having a density of 0.9 kg/m2 and a size of 300 x 300 x 30 mm, which consists of 808 by weight of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, 15% by weight of polyester fibers having a fineness of 4-6 denier and 58 by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 5 A sound absorbing member No. 5 is produced by pressing a fiber assembly having a density of 1.0 kg/m2 and a size of 300 x 300 x 30 mm, which consists of 808 by weight of polyester fixers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, 158 by weight of polyester fibers having a fineness of 4-6 denier and 58 by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 6 A sound absorbing member No. 6 is produced by pressing a fiber assembly having a density of 1.3 kg/m2 and a size of 300 x 300 x 30 mm, which consists of 80% by weight of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, 158 by weight of polyester fibers having a fineness of 4-6 denier and 58 by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 7 A sound absorbing member No. 7 is produced by pressing a fiber assembly having a density of 0.8 kg/m2 and a size of 300 x 300 x 30 mm, wr. consists cf 60; by e$rht of polyester fibers havIng a fI- eness cf not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equlvalent/g, 30% by weight of polyester fibers having a fineness of 4-6 denier and 10% by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 8 A sound absorbing member No. 8 is produced by pressing a fiber assembly having a density of 1.2 kg/m2 and a size of 300 X 300 X 30 mm, which consists of 605 by weight of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, 30% by weight of polyester fibers having a fineness of 4-6 denier and 108 by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 1650C.

Example 9 A sound absorbing member No. 9 is produced by pressing a fiber assembly having a density of 1.4 kg/m2 and a size of 300 x 300 x 30 mm, which consists of 608 by weight of polyester fibers having a fineness of not more than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 x 10-6 equivalent/g, 30% by weight of polyester fibers having a fineness of 4-6 denier and 108 by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 165 C.

Reference Example 3 The same procedure as in Reference Example 1 is repeated by using reclaimed PET having an intrinsic viscosity of 0.35 and carboxyl end groups of 90 , 10-6. In this case, however, yar breakage s freetly cased at a dies portion of a spinning machine and hence good reclaimed PET fibers can not be obtained.

Reference Example 4 The same procedure as in Reference Example 2 is repeated by using reclaimed PET having an intrinsic viscosity of 0.5 and carboxyl end groups of 110 x 10-6. In this case, however, the viscosity largely lowers due. to thermal decomposition of the reclaimed PET in the extrusion spinning machine and the fiber size is largely scattered and hence good reclaimed PET fibers can not be obtained. Furthermore, the resulting reclaimed PET fibers are considerably colored (yellow).

Comparative Example 1 A sound absorbing member is produced by pressing a fiber assembly having a density of 1.0 kg/m2 and a size of 300 x 300 x 30 m, which consists of 208 by weicht of polyester fibers having a fineness of not ore than 4 denier, an intrinsic viscosity of 0.5 and carboxyl end groups of 90 X 10-6 equivalent/g, 30; by weght of pcrnyester ferns having a fiess of 4-6 denier and 508 by weight of polyester fibers having a fineness of not less than 6 denier, under a pressure of 50 kgf/cm2 while heating at 1650C.

Conventional Example 1 A sound absorbing member is produced by heating a felt comprised of disentangled synthetic fibers and natural fibers and having a size of 300 x 300 x 30 mm and a density of 1.0 kg/m2 at 2000C and then pressing under a pressure of 50 kgf/cm2.

Conventional Example 2 A sound absorbing member is produced by heating a felt comprised of disentangled synthetic fibers and natural fibers and having a size of 300 x 300 x 30 mm and a density of 1.2 kg/m2 at 2000C and then pressing under a pressure of 50 kgf/cm2.

Conventional Example 3 A sound absorbing member is produced by heating a felt comprised of disentangled synthetic fibers and natural fibers and having a size of 300 x 300 x 30 mm and a density of 2.1 kg/m2 at 2000C and then pressing under a pressure of 50 kgf/cm2.

Measurement The intrinsic viscosity and carboxyl end groups are measured as follows.

Measuring method 1 The intrinsic viscosity is measured at 300C by dissolving 1 g of a polymer in 100 ml of a mixed solvent of phenol and tetrachioroethane of 1:1 (weight ratio).

Measuring method 2 The amount of carboxyl end groups is measured by a method described in Analytical Chemistry, 26 (10), 1614 (1954).

Test Example 1 The sound absorption coefficient is measured with respect to each sample of the sound absorbing members obtained in Examples 1-9, Comparative example 1 and Conventional examples 1-3 according to a test method for sound absorption of acoustical material by the tube method defined in JIS-A-1405.

In this case, the size of the sample is 100 mm or 30 mm in diameter, and the frequency range to be measured is 100 Hz - 6.4 kHz.

Test Example 2 The vibration transmissibility is measured with respect to each sample of the sound absorbing members obtained in Examples 1-9, Comparative Example 1 and Conventional Examples 1-3 by vibrating at a vIbration force of 1.5 N within a frequency range of 5-130 Hz. The spring constant (N/m) is calcls=ed for. te measured data.

Test Example 3 The sound transmission loss is measured with respect to each sample of the sound absorbing members obtained in Examples 1-9, Comparative Example 1, and Conventional Examples 1-3 according to a method for laboratory measurement of sound transmission loss defined in JIS-A-1416, from which a difference of average sound insulating level (dB) to Conventional Example 2 as a standard is calculated within a frequency range of 200 Hz - 10 kHz.

The test results are shown in Table 1.

Table 1(a)

A B C D E F G H Average Carboxyl end Fiber weight % Fiber weight % Fiber weight % Density Intrinsic fiber size groups of less than 4d of 4-6d of more than 6d kg/m viscosity d (equivalent/g) 1 Example 1 100 0 0 4.00 0.80 0.5 0.00009 2 Example 2 100 0 0 4.00 1.30 0.5 0.00009 3 Example 3 100 0 0 4.0 1.60 0.5 0.00009 4 Example 4 80 15 5 4.30 0.90 0.5 0.00009 5 Example 5 80 15 5 4.30 1.00 0.5 0.00009 6 Example 6 80 15 5 4.30 1.30 0.5 0.00009 7 Example 7 60 30 10 4.50 0.80 0.5 0.00009 8 Example 8 60 30 10 4.50 1.20 0.5 0.00009 9 Example 9 60 30 10 4.50 1.40 0.5 0.00009 Comparative 10 20 30 50 5.30 1.00 0.5 0.00009 Example 1 Conventional 11 - - - - 1.00 - Example 1 Conventional 12 - - - - 1.20 - Example 2 Conventional 13 - - - - 2.10 - Example 3 Table 1(b)

A I J K L M N O Evaluation Sound Sound Sound Spring transmission absorption absorption sound constant loss (dB) coefficient coefficient economical insulating N/m 200~10 kHz total (500 Hz) (1 kHz) efficiency performance average 1 Example 1 56200 0.21 0.43 0.56 2 Example 2 60000 0.30 0.62 1.34 3 Example 3 67600 0.32 0.68 1.63 4 Example 4 53500 0.26 0.56 0.86 5 Example 5 61200 0.26 0.57 0.93 6 Example 6 73600 0.28 0.63 1.21 7 Example 7 54800 0.20 0.40 0.70 8 Example 8 72500 0.25 0.54 1.00 9 Example 9 72600 0.26 0.58 1.14 Comparative 10 80100 0.20 0.44 -0.15 x Example 1 Conventional 11 84900 0.20 0.45 -0.20 x x Example 1 Conventional 12 92100 0.21 0.46 standard 0.00 standard x Example 2 Conventional 13 242000 0.26 0.50 0.20 x x Example 3 As seen from Table 1, the sound absorbing members according to the invention are low in the spring constant and high in the sound absorption coefficient as compared with the conventional ones, from which the sound insulating performance is suggested to be high as compared with the conventional one. On the other hand, satisfactory values of the performances can not be obtained in Comparative Example 1 prepared by the specification outside the scope of the invention.

As mentioned above, the sound absorbing member according to the invention is constructed with the fiber assembly of new polyester fibers or reclaimed polyester fibers having a regulated fineness, so that it maintains sound insulating and absorbing performances higher than those of the conventional felt and is low in the cost and high in the economical efficiency. Furthermore, when the reclaimed polyester fibers are used in the fiber assembly, the resulting sound absorbing member can be applied to a field not utilizing the recycled product, so that the contribution t

Claims

C1aLs:

1. A sound absorbing member comprising a fiber assembly s-5stantially consisting of short fibers and having a thickness of not less than 5 mm, in which polyester fibers are used as the short fibers and not less than 308 by weight of the polyester fibers used have a fiber size of not more than 4 denier.

2. A sound absorbing member according to claim 1, wherein the polyester fiber is a reclaimed polyester fiber produced by using a reclaimed polyester material having an intrinsic viscosity of not less than 0.4.

3. A sound absorbing member according to claim 1, wherein the polyester fiber is a reclaimed polyester fiber produced by using a reclaimed polyester material having carboxyl end groups of not more than 100 x 10-6 equivalent/g.

4. A sound absorbing member according to claim 1, wherein the fiber assembly has a density of not more than 1.5 kg/m2.

5. A sound absorbing member according to claim 1, wherein the fiber assembly contains 5-70% by weight of polyester fibers having a fineness of not less than 6 denier.

6. A sound absorbing member according to claim 1, wherein the fiber assembly has a spring constant of not more than 80,000 N/m.

7. A sound absorbing member for an automobile, comprising a fiber assembly s-k-antoatly consisting of short fibers and having a thickness of not less than 5 mm, in which reclaimed polyester fibers produced from a reclaimed polyester material having an intrinsic viscosity of not less than 0.4 and carboxyl end groups of not more than 100 x 10-6 eq-~ivalent/g are used as the short fibers,and not less than 308 by weight of the reclaimed polyester fibersused have a fiber size of not more than 4 denier.

8. A sound absorbing member comprising a fiber assembly consisting of polyester fibers containing 30-80% by weight of reclaimed polyester fibers in which not less than 30% by weight of the polyester fibersused have a fiber size of not more than 4 denier.

9. A sound absorbing member according to claim 8, wherein the reclaimed polyester fiber is produced by a molten spinning process starting from a reclaimed polyester material having an intrinsic viscosity of not less than 0.4 and carboxyl end groups of not more than 100 x 10-6 equivalent/g.

10. A sound absorbing member according to claim 8, wherein an amount of polyester fibers and/or reclaimed polyester fibers having a fineness of 6-15 denier is 10-80% by weight and the fiber assembly has a thickness of not less than 5 mm.

11. A sound absorbing member according to claim 8, wherein the fiber assembly has a density of 0.4-1.5 kg/m2.

12. A sound absorbing member according to claim 8, wherein the fiber assembly has a spring constant of not more than 80,000 N/m.

13. A sound absorbing member substantially as described with reference to any of Examples 1 to 9.