JP3150846B2 - Fiber molded cushion material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various types of vehicle seats, furniture cushions, bedding mats, bed mats and various cushioning materials molded into various molded shapes such as thick flat or three-dimensional curved surfaces. The present invention relates to a fiber-molded cushion material used in the present invention.

[0002]

2. Description of the Related Art At present, a fiber-formed cushion material used in the field of cushions for vehicle seats, furniture, bedding and the like is formed by webbing short fibers containing heat-adhesive fibers, and then compressing and thermoforming (for example). , Tokuhei 1-18
183, JP-A-4-126856, JP-A-3-220354 and the like. However, conventional fiber molded cushion materials have low elasticity when compressed, have a hard texture, have a large change in texture, hardness, and thickness due to compression during use, and change in form due to breakage of adhesion points. There are drawbacks such as occurrence. In addition, in order to improve the texture and set, changing the low-melting polymer or changing the cross-sectional shape of the low-melting fiber has problems such as poor spinnability during fiberization and high cost. The adhesiveness with the polyester fiber as the skeleton is not sufficiently improved, and the cushioning properties are insufficient (Japanese Patent Laid-Open No. 4-126856). In the case of changing the shape of the high melting point fiber, the drawback is that the shrinkage during molding is too large due to the appearance of latent crimping during heat treatment, which is inconvenient, and the trouble and unevenness in the card when forming into a web are large And the skeleton is made of polyester fiber, so that the strain applied by compression tends to remain, resulting in insufficient durability (Japanese Patent Laid-Open No. 3-220354). In the one that is configured to melt all the low-melting fiber at the processing temperature and adhere in a skewer,
Due to the large shrinkage of the low-melting fiber that occurs before fusing, there are drawbacks in that the shape of the molded product becomes unstable and uneven thickness and density occur. Therefore, the texture when subjected to compression has low elasticity, is coarse and hard, and has low compression durability (Japanese Patent Publication No. 1-18183). In addition, these fiber molded cushion materials are rigid and hard because the high melting point fiber constituting the skeleton is composed of a conjugate polymer composed of a polyester polymer alone or a combination of polyester polymers. The material has low elasticity and is coarse and hard. There is a limit to the recovery from compression deformation, and large deformation is applied for a long time, and a cushion material subjected to repeated deformation has a problem in durability against a change in thickness and a change in compression characteristics.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems in such a conventional fiber molded cushion material.
That is, it is an object of the present invention to provide a fiber-molded cushion material in which the texture is hard and coarse and hard, there is no elasticity, the texture when compressed, the hardness, and the rate of change in thickness is large. .

[0004]

According to the present invention, there is provided (claim 1) a polyester-based crimped staple fiber and a low-melting staple fiber having a melting point lower than that of the staple fiber by 30 ° C. or more. In the fiber molded cushion material, the polyester crimped short fiber is a non-elastomeric polyester 9
8 to 50 parts by weight and elastomeric polyester 2 to 5
A fiber molded cushion material comprising a homogeneous mixture composition with 0 parts by weight. (Claim 2) The fiber molded cushion material according to claim 1, wherein at least a part of the polymer constituting the low melting point fiber is made of a polyester elastomer. (Claim 3) The fiber molded cushion material according to claim 2, wherein the low melting point fiber is a conjugate fiber, and a majority of the fiber surface is covered with a polyester elastomer. (Claim 4) The polyester elastomer uniformly mixed in the polymer constituting the polyester crimped staple fiber and the polyester elastomer constituting at least a part of the polymer constituting the low melting point fiber are the same polyester elastomer. The fiber molded cushion material according to claim 2 or 3. ".

[0005] The polyester-based crimped staple fiber in the present invention comprises a homogeneous mixture of 98 to 50 parts by weight of a non-elastomeric polyester and 2 to 50 parts by weight of an elastomeric polyester. Non-elastomeric polyesters include ordinary polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate,
It is an ordinary polyester polymer composed of poly-1,4-dimethylcyclohexane terephthalate, polypivalolactone or a copolymer ester thereof.

The elastomeric polyester is a polyetherester block copolymer obtained by copolymerizing a thermoplastic polyester as a hard segment and a poly (alkylene oxide) glycol as a soft segment, more specifically, terephthalic acid, isophthalic acid, Phthalic acid,
Naphthalene-2,6-dicarboxylic acid, naphthalene 2,7
-Dicarboxylic acid, diphenyl-4,4-dicarboxylic acid,
Diphenoxyethane dicarboxylic acid, aromatic dicarboxylic acid such as sodium 3-sulfoisophthalate, alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, succinic acid, oxalic acid, adipic acid, sebacic acid, dodecane diacid, At least one dicarboxylic acid selected from aliphatic dicarboxylic acids such as dimer acid, or ester-forming derivatives thereof, and 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexa Aliphatic diols such as methylene glycol, neopentyl glycol, decamethylene glycol and the like, or alicyclic diols such as 1,1-cyclohexane dimethanol, 1,4-cyclohexane dimethanol and tricyclodecane dimethanol, or And at least one diol component selected from the ester-forming derivatives thereof, and polyethylene glycol, poly (1,2- and 1,3-propylene oxide) glycol, poly (tetramethylene) having an average molecular weight of about 400 to 5,000. Terpolymers composed of at least one of poly (alkylene oxide) glycols, such as (oxide) glycol, a copolymer of ethylene oxide and propylene oxide, and a copolymer of ethylene oxide and tetrahydrofuran.

However, from the viewpoints of miscibility with general polyesters, spinnability, temperature characteristics, physical properties, etc., a block copolymerized polyether polyester having polybutylene terephthalate as a hard segment and polyoxytetramethylene glycol as a soft segment. Is preferred. In this case, the polyester portion constituting the hard segment is polybutylene terephthalate in which the main acid component is terephthalic acid and the main diol component is a butylene glycol component. Of course, a part of this acid component (usually 3
(0 mol% or less) may be substituted with another dicarboxylic acid component or oxycarboxylic acid component, and similarly, a part of the glycol component may be substituted with a dioxy component other than the butylene glycol component. Further, the polyether component constituting the soft segment may be a polyether substituted with a dioxy component other than tetramethylene glycol. In the polymer, various stabilizers, ultraviolet absorbers, thickening and branching agents, matting agents, coloring agents, and other various improvers may be added as necessary.

The mixing ratio of the non-elastomeric polyester to the elastomeric polyester is 98 to 50 parts by weight for the non-elastomeric polyester and 2 to 50 parts by weight for the elastomeric polyester. When the mixing ratio of the non-elastomeric polyester exceeds 98 parts by weight and the mixing ratio of the elastomeric polyester is less than 2 parts by weight, the amount of the elastomer component is too small, and the strain recovery of the skeleton fiber decreases. When the mixing ratio of the non-elastomeric polyester is less than 50 parts by weight, and when the mixing ratio of the elastomeric polyester exceeds 50 parts by weight, the modulus of the fiber serving as the skeleton becomes too low, so that it is difficult to maintain bulkiness during molding. Therefore, it is difficult to obtain a low-density fiber molded cushion material. In addition, the resilience of the molded fiber molded cushion material is also reduced.

As a method of uniformly mixing the polyester elastomer, a general polyester resin and a polyester elastomer are mixed in a chip state,
Examples include a method of extruding and spinning with a ruder while melting, and a method of adding and mixing during polymerization. It is necessary that the polyester elastomer is uniformly present in the polyester polymer, and a part thereof may be reactively bonded to the polyester by a transesterification reaction, may be mixed in a finely dispersed state, or may be a polymer arrangement. It may be distributed in a streak like a body.

[0010] The polyester-based crimped short fibers may be a cotton blend containing fibers of the above composition, or a conjugate fiber composed of two or more of the above polymers. The cross-sectional shape of the short fiber may be any of a circle, a flat, an irregular shape, and a hollow. In addition, spiral crimping or indentation crimping by anisotropic cooling or conjugate, or ω by combination of both.
It may be a mold crimp.

The conventional general polyester polymer has a limit in strain recovery from applied compressive deformation,
With repeated compression, distortion due to deformation remains and the thickness becomes thinner, and the recovery stress against compression deformation is small.
On the other hand, when a polyester elastomer is uniformly mixed with a normal polyester polymer, the recovery from deformation is extremely improved, and the fibers constituting the framework of the heat-fixed fiber-molded cushioning material also recover the strain from compression deformation. And the durability is improved because the resilience is also improved as a cushion material. Of course, the hardness and elasticity of the fiber are also greatly improved by uniformly mixing the polyester elastomer, and the texture, elasticity and thermal adhesiveness of the heat-bonded fiber molded cushion material are greatly improved. To improve.

Crushed polyester fibers are
Because it is a matrix that serves as a framework for
Use something. The bulkiness (JIS-L-1097)
0.5g / cm^Three40cm under the load of^Three/ G or more, 10
g / cm^Three15cm under the load of ^Three/ G or more is preferred
Preferably, more preferably, 50 cm each.^Three/ G or less
Top, 20cm^Three/ G or more. Low bulkiness of these
And the elasticity and compression rebound of the obtained fiber molded cushion material
The problem of low propensity becomes significant.

The fineness of the polyester crimped staple fiber is from 2 to
A range of 500 denier is preferred, more preferably 4 denier.
~ 200 denier. If the fineness is less than 2 denier, the bulkiness is not exhibited, and the cushioning property and the repulsion are poor. On the other hand, if it is larger than 500 denier, it is difficult to form a web, and the number of constituent fibers of the obtained fiber molded cushion material is too small, so that only those having poor cushioning properties can be obtained.

On the other hand, the number of crimps of the polyester crimped short fibers is preferably 4 to 25 pieces / inch, and the degree of crimp is preferably 20 to 40%. If the number of crimps and the degree of crimp are too small, the bulk of the web hardly appears and it is difficult to form a web, which is not preferable. The resulting cushioning material also has poor resilience and can only be obtained with low durability. On the other hand, if the number of crimps and the degree of crimp are too large, the bulkiness of the web is not increased, and only a high-density cushion material is obtained. Is not preferred.

On the other hand, the cushioning material of the present invention is a short fiber in which a low melting point polymer having a melting point lower than the melting point of the polyester crimped short fiber by 30 ° C. or more forms at least a part thereof. Melts and fuses with polyester crimped short fibers or low melting point fibers. Here, when a plurality of melting peaks are recorded by differential thermal analysis, the melting point of the polyester-based crimped staple fiber is defined as the temperature on the high temperature side. If this melting point difference is less than 30 ° C., the processing temperature becomes close to the melting point of the polyester-based short fibers, the physical properties and crimping properties of the polyester short fibers are reduced, the cushioning performance is deteriorated, and the shrinkage during molding is increased. .

The heat-fusible fibers include known copolyester fibers, fibers containing a thermoplastic elastomer, polyolefin fibers, polyvinyl alcohol fibers and the like. In particular, a conjugate fiber containing a low-melting-point polymer as a component is preferable because it has excellent shape retention stability and moldability. The composite form is preferably a side-by-side type, a core-sheath type, an eccentric core-sheath type, or the like. In particular, a composite form in which the low melting point component is exposed on the surface is preferable. The non-adhesive component of the conjugate fiber is preferably a general polyester, but the polymer composition constituting the polyester crimped staple fiber is particularly preferable.

However, after hot-sealing molding, it is repeatedly compressed and deformed, and the amount of compression or deformation is large (for example,
In a cushioning application (50% of the thickness), it is necessary to be easily deformed when a deforming stress is applied to the heat fixing point, and to return to the original position without leaving a distortion when the deforming stress is removed. is there. When a large deformation is applied to the fiber molded cushion body, further deformations such as a large angle change, stretching, twisting, etc. are applied to the entanglement point composed of the low melting point polymer of the fiber constituting the fiber structure. Therefore, the heat-fixing polymer needs to have a property of largely deforming and recovering, and is preferably made of a thermoplastic elastomer having a large breaking elongation and a good elongation recovering property. For that purpose, the compression treatment after the molding heat treatment and cooling is more effective. In a conventional low melting point polymer having a low elongation and low elongation elastic recovery, even at a compression rate of about 40%, the bonding point is broken by a slight deformation and the compression hardness is remarkably reduced. If it becomes too small or severe, it becomes floc. Because the thermoplastic elastomer of the present invention has a high elongation and elongation recovery rate, the decrease width by the compression treatment is small,
The decrease during use is also small at the initial stage, and the change during use is also small. In particular, the thermoplastic elastomer is heat-resistant because it is molded at a high temperature. A polyester-based elastomer is particularly preferable because the matrix fiber to be heat-fixed is a polyester-based fiber and a polyester-based elastomer is uniformly mixed in a part of its components. In the case of heat-sealing, the same polyester system greatly improves the adhesive strength.

The polyester elastomer having a low melting point may be any of the above-mentioned polyester elastomers, and may be different from the polyester elastomer contained in the polyester crimped short fibers. Considering this, it is particularly preferable to use the same polyester elastomer.

The single fiber fineness of the short fiber containing the low melting point polymer is preferably 2 to 150 denier, and the fiber length is 38 to 2 denier.
55 mm, crimping is preferably 4 to 50 pieces / inch. Outside of this range, it is difficult to mix or web. In addition, the cushion performance and compression durability of the molded product also deteriorate.

The mixing ratio of the low-melting fiber is 10 to 70% by weight.
Is preferred. If the ratio of the low melting point fiber is less than 10% by weight, the number of the bonding points of the fiber structure becomes insufficient, and the compression rebound and the compression durability are lowered. On the other hand, when the ratio is higher than 70% by weight, the number of bonding points of the fibrous structure is too large, and the fiber structure becomes hard and the cushioning property is reduced. In addition, the shape of a molded product designed in advance is difficult to obtain due to shrinkage of the low melting point fiber.

The density of the cushion material is 0.005 to 0.1
g / cm ³ is preferable, and the thickness of the cushioning material is ³ g / cm 3.
~ 1000 mm is preferred. If the density is lower than this range, the resilience and compression durability fall below the practical range. On the other hand, if the density is too high, on the contrary, the fiber density and the density of the bonding points are too high and become hard. When the thickness is less than 3 mm, the cushioning property is not exhibited. If the thickness exceeds 1000 mm, it is practically unsuitable as a cushion material.

In the present invention, a polyester-based crimped short fiber in which a polyester elastomer is uniformly mixed and a low-melting short fiber are mixed, opened with a card or the like, and formed into a web.
Laminate webs and pack a predetermined amount of webs into a mold having air permeability so that a predetermined shape can be obtained, or sandwich a laminated web etc. on a flat plate composed of a punching plate or a caterpillar type upper and lower conveyor, and form a low melting point fiber. Pressing and heating at a temperature higher than the melting point and lower than the melting point of the polyester-based crimped staple fiber to melt the low-melting-point polymer and to form the entanglement between the low-melting-point fiber and the polyester-based short fiber and the low-melting-point fiber. By pressurizing and heating at least a part of the entanglement points and heat-sealing, a fiber forming cushion material having a predetermined shape is obtained.

Here, in the present invention, cooling is performed after heat treatment under pressure, but in order to maintain dimensional stability and physical property stability at higher temperatures, the temperature is kept at a constant temperature equal to or lower than the melting point of the low-melting fiber during cooling. Reheating to a temperature below the melting point of the low-melting fiber after cooling or cooling is a preferred embodiment. After cooling, it is also a preferable method to compress and remove incomplete bonding portions in advance. The compression ratio (the amount of compression in the thickness direction with respect to the thickness of the cushion material measured with an initial load of 0.5 g / cm ² ) when performing this compression treatment is preferably 40 to 95%.

[0024]

【The invention's effect】

(1) The fiber molded cushion material of the present invention is a cushion material molded using a polyester fiber as a skeleton, in which an elastomer having excellent elasticity and recovery properties is uniformly mixed in the fiber as compared with the conventional fiber molded cushion material. Therefore, the elasticity with respect to compression is extremely high, and the durability of the cushioning material to which repeated large deformation is applied is extremely high due to its excellent deformation recovery.

(2) Since these cushioning materials are all made of thermoplastic fibers, they can be re-melted after use and recycled again into new fibers, molded plastics and the like. In particular, it is also possible to use the new polymer as a skeleton fiber of the cushioning material while partially using the new polymer, or to use it as a non-adhesive component of a part of the low melting point fiber. In addition, generation of toxic gas upon combustion is small. Therefore,
The three-dimensionally curved or planar thick cushion material obtained by these heat treatments is suitable as a fiber-forming cushion material used for various vehicle seats, furniture cushions, bedding mats, bed mats, various cushion materials, and the like.

Hereinafter, the present invention will be described specifically with reference to examples. Each evaluation item in the examples was evaluated according to the following methods. <Crimping performance; number of crimps, degree of crimping> According to JIS L-1015. <Compression residual strain> According to JIS K-6401. <80,000 times compression residual strain> According to JIS K-6401. <80,000 times hardness retention> Compressive stress (F0) and JI at the time of initial compression of 75% and then compression of 25% again
Repeated compression 80,000 times by SK-6401,
After standing for 75 minutes, a pre-compression of 75% was applied, and the compression stress (F1) when compressed again by 25% was measured, and [(F1 /
F0) × 100%]. <Melting point> Using a Differential Thermal Analyzer Model 990, manufactured by Dupont, the temperature was measured at a heating rate of 20 ° C./min, and the melting peak was determined. If the melting temperature is not clearly observed,
Using a trace melting point measuring device (manufactured by Yanagimoto Seisakusho), about 3 g of the polymer was sandwiched between two cover glasses, and the temperature was raised at a heating rate of 20 ° C./min while lightly pressing with tweezers to observe the thermal change of the polymer. . In this case, the temperature at which the polymer softens and starts to flow (softening point) is defined as the melting point here. <Bulkiness of web> According to JIS L-1097.

[0027]

Example 1 Terephthalic acid and isophthalic acid were mixed at 88/1
2 (mol%) of the acid component mixed with butylene glycol to obtain polybutylene-based terephthalate 38.
% (% By weight) was further reacted with 62% (% by weight) of polytetramethylene glycol (molecular weight: 2000) to obtain a block copolymerized polyester elastomer, which was formed into chips according to a conventional method. The melting point of this thermoplastic elastomer is 1
69 ° C. 20% by weight of this polyester elastomer chip and 80% by weight of polyethylene terephthalate chip (melting point: 256 ° C.) obtained according to a conventional method are mixed and supplied to an extruder, melted, anisotropically cooled, 14 denier, hollow The fiber was formed into a fiber having a ratio of 23%, further subjected to indentation crimping, and then heat-treated and cut to obtain an ω-type crimped polyester-based crimped short fiber having a fiber length of 64 mm. The melting point was 253 ° C.

On the other hand, the thermoplastic polyester elastomer is used as a sheath, and polybutylene terephthalate (melting point: 224 ° C.) obtained by a conventional method is used as a core. Was spun by a conventional method. The composite fiber was an eccentric sheath / core type composite fiber. The obtained fiber was stretched 2.0 times, dried at 80 ° C., developed crimp, applied an oil agent, and cut into 64 mm. The single-filament fineness of the obtained composite low melting point fiber is 9 deniers and the number of crimps is 16
The pieces / inch and the degree of crimp were 30%.

30% by weight of this conjugate fiber and polyester-based crimped short fibers (number of crimps: 9 / inch, degree of crimp: 34%, bulk specific gravity: 75 cm ³ / g under a load of 0.5 g / cm ² ,
Under a load of 0 g / cm ² , 70% by weight of 30 cm ³ / g) was mixed, and the mixture was webbed with a card and laminated to obtain a laminated web. This web was sandwiched in a flat air-permeable mold so as to have a thickness of 5 cm and a density of 0.035 g / cm ^{3, and} was subjected to a pressurizing / heating treatment in a hot air oven at 200 ° C. for 5 minutes, and then cooled at room temperature.

The texture of the obtained cushioning material was soft, not coarse and hard, and very elastic. Table 1 shows the performance of the obtained cushion material. The durability of this cushion material is repeated (compression of 80,000 times) and the durability in a high temperature atmosphere (70 ° C).
(Compression set) was very good as compared with the case where the polyester elastomer was not blended. The cushion material after the compression treatment of 80,000 times had a feeling that the change was hard to be understood even in comparison with the initial stage, and the durability was very good.

[0031]

COMPARATIVE EXAMPLE 1 Polyester terephthalate alone was used as the composition of the polyester-based crimped staple fiber without uniformly blending the polyester-based elastomer with a denier of 14 denier and a hollow ratio of 23% (the number of crimps was 9 / inch, crimped). Degree 30%, bulk specific gravity 77 cm under a load of 0.5 g / cm ^2
3 / g, 32 cm ³ / g) under a load of 10 g / cm ² , and was used in the same manner as in Example 1 except that this was used in place of the polyester-based crimped short fiber, to obtain a fiber molded cushion material. Was. The obtained fiber molded cushion material had a rough and hard feeling, was hard, and had a low elasticity. Table 1 shows the performance of the cushion material. The residual strain after 80,000 compressions is poor,
The hardness retention after the compression treatment of 80,000 times was very poor. Further, it was felt that the feel of the cushion material after the 80,000 compression treatments was significantly different from that of the initial stage.

[0032]

Example 2 85% by weight of polybutylene terephthalate (melting point: 224 ° C.) chips obtained by a conventional method and 85% by weight
15% by weight of the thermoplastic elastomer chip obtained by the above method was mixed to obtain a denier of 20%, a hollow ratio of 10%, and a fiber length of 64.
mm indented crimped polyester crimped short fibers were obtained. Melting point was 222 ° C. This polyester crimped short fiber (10 crimps / inch, degree of crimp 28%, bulk specific gravity 63 cm ³ / g under load of 0.5 g / cm ² , 10 g /
Example 1 with 70% by weight of 22 cm ³ / g) under a load of ² cm ²
Was mixed with 30% by weight of the composite low-melting fiber to form a web, and a flat cushion material having a thickness of 5 cm and a density of 0.045 g / cm ³ was obtained in the same manner as in Example 1. The obtained cushioning material was very soft and excellent in elasticity. The performance is shown in Table 2. The obtained cushioning material was excellent in durability, small in compression residual strain at 70 ° C., and very excellent.

[0033]

Comparative Example 2 The same procedure as in Example 2 was carried out except that the thermoplastic elastomer was not mixed into the polybutylene terephthalate. Crimp degree: 26%, bulk specific gravity: 65 cm ³ / g under load of 0.5 g / cm ² , 10 g / c
This was carried out in the same manner as in Example 2 using 24 cm ³ / g under a load of m ² to obtain a flat cushion material. Table 2 shows the performance of the obtained cushion material. This cushion material had a high residual compression set, and the durability after 80,000 compressions was not very good.

[0034]

Comparative Example 3 A polyester crimped short fiber was obtained in the same manner as in Example 1 except that the amount of the thermoplastic elastomer chip was changed to 55% by weight. The resulting crimped staple fiber has a number of crimps of 7 pieces / inch, a degree of crimp of 20%, and a bulk specific gravity of 0.1.
55 cm ³ / g, 10 g / cm ² under a load of 5 g / cm ²
It was as low as 15 cm ³ / g under load. 70% by weight of the polyester-based crimped short fibers and 30% by weight of the composite low melting point short fibers of Example 1 were mixed together, formed into a web, and molded to obtain a flat cushion material having a thickness of 5 cm and a density of 0.045. Table 2 shows the performance of the obtained cushion material. The obtained cushioning material had low repulsion, and the cushioning material was unsuitable. In addition, the residual strain after 80,000 compressions was large and the durability was low.

[0035]

[Table 1]

[0036]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-40239 (JP, A) JP-A-58-31150 (JP, A) JP-A-62-177269 (JP, A) JP-A-5-31269 311559 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D04H 1/00-18/00 B68G 1/00-15/00

Claims (4)

(57) [Claims] 1. A fiber molded cushion material comprising polyester-based crimped staple fibers and low-melting-point staple fibers having a melting point lower than that of the staple fibers by 30 ° C. or more. A fiber molded cushion material, wherein the fibers are composed of a homogeneous mixture of 98 to 50 parts by weight of a non-elastomeric polyester and 2 to 50 parts by weight of an elastomeric polyester. 2. The fiber molded cushion material according to claim 1, wherein at least a part of the polymer constituting the low melting point fiber is made of a polyester elastomer. 3. The fiber molded cushion material according to claim 2, wherein the low melting point fiber is a conjugate fiber, and a majority of the fiber surface is covered with a polyester elastomer. 4. A polyester elastomer which is uniformly mixed in a polymer constituting a polyester crimped short fiber and a polyester elastomer constituting at least a part of a polymer constituting a low melting point fiber. The fiber molded cushion material according to claim 2 or 3, wherein