JPH07126973A - Production of fiber-formed cushioning material - Google Patents

Abstract

PURPOSE:To obtain a fiber-formed cushioning material hardly changing the touch feeling, hardness and thickness by hot-pressing a laminated web composed of partially fused and bonded fiber having different melting points, cooling the hot-pressed web and then carrying out the compression treatment at least once. CONSTITUTION:This method for producing a fiber-formed cushioning material is to hot-press a web composed of polyester-based staple fiber and low-melting staple fiber having a lower melting point than that of the former fiber by >=40 deg.C, e.g. a thermoplastic polyester-based elastomer to a temperature above the melting point of the low-melting fiber and below the melting point of the polyester-based staple fiber, fuse and bond at least a part of crossover points of the low-melting staple fiber, cool the hot-pressed web and then carry out the compression treatment at 40-95%, preferably 50-90% compression ratio at least once (as necessary, about three times). The resultant fiber-formed cushioning material has soft feeling and hardly changes the touch feeling, hardness and thickness when undergoing compression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-molded cushion material used for vehicle seats, furniture cushions, bedding mats and the like.

[0002]

2. Description of the Related Art At present, as a fiber-formed cushioning material used for vehicle seats, furniture cushions, bedding mats, etc., a method of web-forming short fibers containing heat-adhesive fibers, followed by compression and thermoforming (for example, , Tokkyo 1-18
183, JP-A-4-126856, JP-A-3-220354) and a cushion structure (PCT / JP9) in which inelastic fibers are fixed with a thermoplastic elastomer.
1/00703) and the like are known.

However, the conventional fiber-formed cushion material has a hard texture, and the texture and hardness due to compression during use,
There was a drawback that the change in thickness was large. In particular, in order to improve the feeling and fatigue, changing the low melting point polymer or changing the cross-sectional shape of the low melting point fiber, the spinnability at the time of fiberizing becomes poor, and the process is complicated. (Japanese Patent Application Laid-Open No. 4-126856), there is a problem in that the cross-sectional shape of the high melting point fiber is changed and the molding shrinkage is too high due to latent crimp development during heat treatment. However, there is a drawback that the unevenness of the card is large when it is made into a web (JP-A-3-220354). When all low melting point fibers are melted and adhered in a skewered shape, there is a drawback that the molding shape becomes unstable due to the shrinkage of the low melting point fiber that occurs before fusion, resulting in uneven thickness and uneven density. (Japanese Patent Publication No. 1-18183). However, in neither case is there any mention of a method for further processing and improvement after thermoforming.

[0004]

OBJECT OF THE INVENTION The object of the present invention is to improve the drawbacks of the conventional fiber-molded cushioning materials, such as the hardness of the texture and the large changes in the texture, hardness and thickness due to compression during use, by a compression treatment. However, as a fiber molded cushioning material used for vehicle seats, furniture cushions, bedding mats, etc., it has a softer texture than before, and changes in texture, hardness, and thickness when repeatedly compressed. An object of the present invention is to provide a method for producing a small amount of fiber-molded cushion material.

[0005]

That is, the present invention provides a web comprising a polyester type short fiber and a low melting point short fiber having a melting point lower than that of the polyester by 40 ° C. or more. As described above, in the method for producing a fiber-molded cushioning material in which at least a part of the entanglement points of the low-melting-point short fibers are fusion-bonded by being pressed and heated at a temperature not higher than the melting point of the polyester-based short fibers, after heating under pressure, cooling, A method for producing a fiber-formed cushion material, which comprises performing compression treatment at least once with a compression ratio of ˜95% (Claim 2) The fiber-formed cushion according to claim 1, wherein the low-melting-point short fibers are made of a thermoplastic elastomer. (Claim 3) A method for producing a fiber-molded cushioning material according to claim 1, wherein a majority of the fiber surface of the low melting point short fibers is covered with a thermoplastic elastomer in the fiber cross section. . (Claim 4) The process according to claim 2 or 3 of the fiber molded cushioning material is a polymer constituting the low melting staple fibers is a polyester-based elastomer. "A.

The polyester short fibers in the present invention are ordinary polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate,
Short fibers made of polytetramethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, polypivalolactone or a copolymer ester thereof, a blended body of those fibers, or two or more kinds of the above polymers Such as a composite fiber. The cross-sectional shape of the short fibers may be circular, flat, irregular or hollow.

Since polyester type short fibers are a matrix that is fused by low melting point fibers to form a frame of a cushion material, even polyester type short fibers alone need to be bulky. The bulkiness alone is 50 cm ³ / g or more under a load of 0.5 g / cm ² and 20 under a load of 10 g / cm ^2.
cm ³ / g or more, more preferably,
Each, 60cm ³ / g or more, and preferably in 25 cm ³ / g or more. If the bulkiness is low, the elasticity and compression repulsion of the obtained fiber molded cushion material will be insufficient.

The single yarn fineness of the polyester staple fiber is 2 to
A range of 500 denier is preferred, more preferably 4
~ 200 denier. If the single yarn fineness is less than 2 denier, the bulkiness is not exhibited, and the cushioning property and the repulsion force become poor. Further, when it is more than 500 denier, it is difficult to form a web, and the number of constituent fibers of the obtained fiber cushion material is small, so that only a cushioning material having poor cushioning properties can be obtained.

The number of crimps of the polyester type short fiber is 4 to 2
5 pieces / inch, and the crimping degree is preferably 20 to 40%. If the number of crimps or the degree of crimping is too small, the web is less likely to be bulky and web formation is difficult, which is not preferable. Further, the obtained cushioning material has poor resilience, and only a material having low durability can be obtained. If the number of crimps or the degree of crimping is too large, the bulkiness of the web is low, and only a high-density cushioning material can be obtained, or the fibers are strongly entangled when the web is formed, and streaky unevenness occurs, which is not preferable. .

On the other hand, the low melting point short fibers of the present invention are short fibers whose low melting point polymer having a melting point of 40 ° C. or more lower than the melting point of polyester short fibers constitutes at least a part thereof, and at least the surface thereof is heated. Part of the melted,
The polyester short fibers and the low melting point short fibers or the low melting point short fibers are fused at the entanglement points. If this difference in melting point is less than 40 ° C., the processing temperature will be close to the melting point of the polyester short fibers, the physical properties and crimping properties of the polyester short fibers or the cushioning performance of the fiber molded cushion material will deteriorate, and the shrinkage during molding will increase. .

Examples of the heat-fusible fibers include copolyester fibers, thermoplastic elastomer fibers, polyolefin fibers, polyvinyl alcohol fibers and the like. In particular,
A composite fiber having a low melting point polymer component is preferable because it is excellent in shape retention stability and moldability. The complex form is
It is a side-by-side type, a core-sheath type, an eccentric core-sheath type and the like. A cross-sectional form in which the low melting point component is exposed on the surface is preferable. However, in cushioning applications in which the amount of compression, that is, the amount of deformation is large due to repeated compressive deformation (for example, 50% of the thickness), when the deformation stress is applied to the heat fixing point, the deformation is easy, and when the deformation stress is removed. Must be restored without leaving any distortion. When a large amount of deformation is applied to the fiber-molded cushion material, a larger angle change, extension, twist, etc. are applied to the low-melting point polymer entanglement point (heat-fixing point) constituting the fiber-molded cushion material. Therefore, this heat-fixing point polymer needs to have sufficient deformation recovery characteristics, and for that purpose, a thermoplastic elastomer having a high fracture elongation and an excellent elongation recovery characteristic is preferable. Especially after being molded once,
The compression treatment after cooling the molding heat treatment is more effective. In the conventional low melting point polymer with low elongation and elongation elastic recovery rate, the thermal fixation point (bonding point) is destroyed and the compression hardness is remarkably lowered, and the desired thickness can be obtained even with the compression treatment of about 40% compression rate. No, it becomes cotton-like in extreme cases. Since the thermoplastic elastomer has high elongation and elongation recovery, the decrease due to the compression treatment is small.

As the thermoplastic elastomer, in the present invention in which the matrix fiber is a polyester fiber,
A polyester elastomer having heat resistance and capable of being thermoformed at high temperature is particularly preferable. As a polyester elastomer, thermoplastic polyester is used as a hard segment,
Polyetherester block copolymer obtained by copolymerizing 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, diphenoxyethanedicarboxylic acid, 3-
Aromatic dicarboxylic acids such as sodium sulfoisophthalate, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, succinic acid, oxalic acid, adipic acid, sebacic acid, dodecanedioic acid, aliphatic dicarboxylic acids such as dimer acid, Or at least one dicarboxylic acid selected from these ester-forming derivatives, 1,4-butanediol, ethylene glycol, trimethylene glycol,
Aliphatic diols such as tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol and decamethylene glycol, and fats such as 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and tricyclodecanedimethanol. At least one diol component selected from cyclic diols or ester-forming derivatives thereof, and polyethylene glycol, poly (1,2- and 1,3-propylene oxide) glycol having an average molecular weight of about 400 to 5,000. , Poly (tetramethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, copolymers of ethylene oxide and tetrahydrofuran, etc. Terpolymer composed from one and the like.

A block copolymerized polyether polyester having polybutylene terephthalate as a hard segment and polyoxytetramethylene glycol as a soft segment is particularly preferable from the viewpoints of adhesiveness with polyester short fibers, temperature characteristics, strength and physical properties. . The polyester portion constituting the hard segment is polybutylene terephthalate whose main acid component is terephthalic acid and whose main diol component is butylene glycol component. A part (usually 30 mol% or less) of the acid component may be replaced with another dicarboxylic acid component or an oxycarboxylic acid component, and similarly, a part of the glycol component may be replaced with a dioxy component other than the butylene glycol component. Good. Further, the polyether component constituting the soft segment may be a polyether substituted with a dioxy component other than tetramethylene glycol. Incidentally, various stabilizers, ultraviolet absorbers, thickening and branching agents, matting agents, coloring agents, and other various improving agents may be added to the polymer as required.

The single yarn fineness of the low melting point short fibers is preferably 2 to 150 denier, the fiber length is 38 to 255 mm, and the crimp is 4
-50 pieces / inch is preferable. Outside this range,
Processes such as blending and webbing become difficult. Also, the cushioning performance and compression durability of the fiber-molded cushioning material are reduced.

The blending ratio of the low melting point fiber is 10 to 70% by weight.
Is preferred. When the ratio of the low melting point fiber is less than 10% by weight, the bonding points of the fiber structure are insufficient, and the compression rebound and the compression durability are reduced. When the ratio of the low melting point fiber is higher than 70% by weight, the number of bonding points of the fiber structure is too large and the fiber structure becomes hard, so that an appropriate cushioning property cannot be obtained. Further, due to the shrinkage of the low melting point fiber, it is difficult to obtain a desired molded product shape.

The density of the fiber molding cushion material is 0.006
The range of up to 0.2 g / cm ³ is preferred. The thickness of the cushion material is preferably 3 mm or more. If the density is less than this range, the fiber density is too low, and the resilience and compression durability fall below the practical range. If the density is too high, on the contrary, the fiber density and the density of the bonding points become too high and the material becomes hard. If the thickness is too thin, cushioning properties will not be exhibited.

In the present invention, polyester short fibers and low melting point short fibers are mixed, opened with a card or the like, made into a web, and if necessary, webs are laminated to obtain a desired shape. A mold having a predetermined amount of web, or sandwiching the laminated web between a flat plate composed of punching plates or a caterpillar type upper / lower conveyor, and heated at a temperature higher than the melting point of the low melting point fiber and lower than the melting point of the polyester short fiber. A fiber-formed cushioning material having a predetermined shape is obtained by performing pressure and heat treatment and heat-sealing at least a part of the entanglement points between the low melting point fibers and the polyester-based short fibers or the entanglement points between the low melting point fibers. Then, it is cooled and compressed. This cooling requires cooling the molded fiber molded cushion material to a temperature lower than the glass transition temperature of the polyester short fibers. If this cooling temperature is too high, a good compression treatment effect cannot be obtained. That is, if the cooling temperature is too high, the rigidity of the fibers that form the skeleton is too low to break the incomplete heat-sealed portion or the fixed portion, and the both ends are heat-sealed and fixed in a bridged fiber. Does not disconnect. Therefore, it cannot be used as a fiber-molded cushioning material with little change in texture, hardness, and thickness in practical use in which it is repeatedly compressed and used.

Compressibility of compression treatment (initial load 0.5 g / c
The amount of compression in the thickness direction after the compression treatment with respect to the thickness of the cushion material measured in m ² ) is required to be 40 to 95%. It is preferably 50 to 90%. If this compression rate is too low,
The amount of deformation of compression is too small to break or peel the incomplete heat-sealed portion or the fixed portion. Further, it is impossible to cut a bridged fiber or the like whose both ends are heat-sealed so as to hinder compression. Therefore, during practical use, their destruction gradually progresses, causing changes in initial hardness, texture, thickness, and the like. Especially, the change is large at the initial stage of use.

On the other hand, if the compression rate of the compression process is too high, the fiber molding cushion material is deformed more than necessary, and the fiber molding cushion material is deformed by proper deformation to contribute to the repulsion, and is restored after the weight is removed. As a result, the skeletal fibers are plastically deformed, and as a result, the original shape cannot be restored. As a result, there arises a serious problem that the resilience is remarkably reduced and the thickness is reduced.

The number of times of compression processing is 3 to 5 times as necessary. This compression treatment method may be performed on the entire fiber-molded cushion material, or may be performed by focusing on the portion used for compression during use. As a compression method, a flat plate shape may be repeatedly pressed to a predetermined compression rate, or a pair of nip rollers having a clearance may be passed. A load may be set, and a similar nip roller may be passed through to apply compression. Of course, performing these in multiple stages is a preferred embodiment. Also, in the case of a molded cushioning material with a three-dimensional curved surface, it is compressed by covering it with a fabric with low air permeability or a non-breathable film to remove air and compress it with a jig that has almost the same compression surface. And the like are preferable.

[0021]

EFFECTS OF THE INVENTION By applying pressure treatment after heating and cooling, the fiber-formed cushioning material of the present invention has a softer texture than conventional fiber-formed cushioning materials and can be repeatedly compressed and used. There is little change in the texture, hardness and thickness of the cushion material when it is pressed. In particular, when a low melting point fiber made of a thermoplastic elastomer suitable for a cushion material is used, the effect of the compression treatment is great, the initial rebound is not significantly reduced, and the change during use is extremely small. Further, since the fiber-formed cushioning material of the present invention is composed entirely of thermoplastic fibers, it can be melted after use and recycled again to new fibers or molded plastic. In addition, the generation of toxic gas during combustion is small.

The fiber-molded cushion material obtained by the method of the present invention is suitable as a seat cushion for various vehicles, a three-dimensionally curved flat seat having various thicknesses, a furniture cushion, and a matton material for bedding.

The present invention will be described below with reference to examples. The evaluation items in the examples were evaluated according to the following methods. <Crimp performance: Number of crimps, crimp degree> JIS-L-1015 <Residual compression strain> JIS-K-6401 <Residual compression strain 80,000 times> JIS-K-6401 <Hardness retention rate at 80,000 times> 25% after pre-compression of 75%
% Compressive stress (F0) and JISK-640
Repeatedly compressed 80,000 times with 1 and left for 30 minutes, then 7
Compressive stress (F
1) was calculated by [(F1 / F0) × 100%]. <Melting point> Using a thermal differential analyzer 990 type manufactured by DUPONT, measurement was performed at a temperature rise of 20 ° C./min to find a melting peak. If the melting temperature is not clearly observed, use a trace melting point measuring device (manufactured by Yanagimoto Seisakusho), sandwich about 3 g of polymer between two cover glasses, lightly press with tweezers, and raise the temperature at a heating rate of 20 ° C / min. Then, the thermal change of the polymer is observed. At this time, the temperature at which the polymer softens and begins to flow (softening point) is defined as the melting point. <Web bulkiness> JIS-L-1097

[0024]

Example 1 80/2 terephthalic acid and isophthalic acid
Polybutylene terephthalate 38 obtained by polymerizing an acid component mixed with 0 (mol%) and butylene glycol
% By weight of polytetramethylene glycol (molecular weight 2
000) 62% by weight and reacted by heating to obtain a block copolymerized polyether polyester elastomer. The melting point of this thermoplastic elastomer was 155 ° C. This thermoplastic elastomer is used as a sheath, polybutylene terephthalate (melting point 224 ° C.) is used as a core, and the sheath /
It was spun by a conventional method so that the weight ratio of the core was 50/50. The composite fiber was an eccentric sheath-core type composite fiber. After stretching the obtained fiber to 2.0 times,
After drying at 80 ° C to develop crimps, apply an oil agent,
It was cut to 64 mm. The obtained composite low melting point fiber has a single yarn fineness of 9 denier, a crimp number of 13 / inch, and a crimp degree of 3
It was 0%.

30% by weight of this composite fiber and polyethylene terephthalate short fiber (single yarn fineness 14
Denier, fiber length 64 mm, crimp number 9 / inch, crimp degree 34%, bulkiness 79 cm ^{3 under} a load of 0.5 g / cm ^2.
/ G, 34 cm ³ / g under a load of 10 g / cm ² , a cross-sectional shape is hollow, and a melting point of 256 ° C.) 70% by weight were mixed and made into a web with a card and laminated to obtain a laminated web. This web was sandwiched in a flat air-permeable mold so that the thickness was 5 cm and the density was 0.035 g / cm ³ ,
The mixture was heat-treated under pressure in a hot air oven at 0 ° C. for 5 minutes, and subsequently cooled at room temperature. At this time, the cooled cushion material is 30 ℃
Met.

The obtained flat plate type cushion material was compressed with a flat plate hydraulic press machine for 0.3 seconds three times until the thickness became 15 mm (compression rate 70%). The cushioning material had an extremely soft texture and was not elastic and had elasticity. Table 1 shows the performance of the cushion material. The durability of the cushion material (80,000 compressions) and the durability in a high temperature atmosphere (70 ° C compression residual strain) were very good as compared with the fiber molded cushion material that was not subjected to compression treatment after cooling. . The cushioning property of the cushioning material after the 80,000-time compression treatment was about the same as the initial feeling. The results are shown in Table 1.

[0027]

[Comparative Example 1] A fiber-molded cushion material was obtained by processing in the same manner as in Example 1 except that pressure heat treatment was carried out in a hot air oven at 200 ° C, and compression treatment was not performed after cooling. The obtained fiber-molded cushion material had a coarse and hard feeling, was hard, and was inferior in elasticity. The performance of this cushion material is shown in Table 1. The residual strain after the 80,000 compression treatment was poor, and the hardness retention after the 80,000 compression treatment was very poor. Further, the cushioning material after the 80,000-time compression treatment had a significantly different feeling compared to that before the initial treatment. The results are shown in Table 1.

[0028]

Example 2 The fiber molded cushion material obtained in Comparative Example 1 was passed twice at a speed of 2 m / min between a pair of nip rollers (roller diameter 20 cm) having a clearance of 10 mm (compression rate 80%). The obtained cushioning material did not have a feeling of coarse and hard texture and was rich in elasticity. The performance of this cushion material is shown in Table 1. The compression durability and hardness retention rate were also good. The sample after repeated compression was good with no change from that before compression (initial stage). The results are shown in Table 1.

[0029]

Example 3 The web obtained in Example 1 was cut into a predetermined size, weight and shape. Two sets of upper and lower breathable three-dimensional punching metal molds were formed so that the shape of an automobile seat was exposed, and predetermined cut webs were arranged at predetermined positions on the lower side (non-bearing surface). Then, the seat surface-shaped mold was covered and fixed from above.
Then, it was placed in a hot air oven at 200 ° C. and heat-treated for 10 minutes to perform thermoforming. Then, it was sufficiently cooled at room temperature to obtain an automobile seat type fiber molded seat cushion material. After cooling, a compression jig having substantially the same shape as this seat surface was used, the upper mold was removed, and the lower mold remained, and compression treatment was performed 5 times so that the thickness became 60%. The seat portion of the automobile cushion sheet obtained here was soft and elastic. In addition, in the wearing test for 6 months while replacing the sheet with the comparative sheet, the initial texture was maintained and the change was small. Also, there were few recesses on the seat surface, and it was almost invisible.

[0030]

Comparative Example 2 An automobile cushion sheet was obtained in the same manner as in Example 3 except that the compression treatment was not performed. The seat surface of the obtained cushion had a coarse and hard feeling and was poor in elasticity.
In the wearing test for 6 months while replacing the seat of Example 3 with the seat, the initial texture was obviously changed. In addition, the recess on the seat surface was partly large, which was a bad recess.

[0031]

Comparative Example 3 The fiber-molded cushion material obtained in Comparative Example 1 was compressed twice by the method shown in Example 1 until the thickness became 2.3 mm. The obtained cushioning material was very soft, the resilience was too low, and the compressive residual strain of the cushioning material was also high. In addition, when the structure was observed with a scanning electron microscope, many bonding points were broken, the hollow cross-section fibers of the matrix were also considerably broken, and the residual strain due to compression was large, which was unsuitable for a cushion material. The results are shown in Table 1.

[0032]

[Table 1]

Claims (4)

[Claims] 1. A web comprising polyester short fibers and low melting short fibers having a melting point lower than that of the fibers by 40 ° C. or more is pressed at a melting point of the low melting fibers or more and a melting point of the polyester short fibers or less. , Heating, in the method for producing a fiber molding cushioning material in which at least a part of the entanglement points of the low melting point short fibers are fusion-bonded, after heating under pressure and after cooling,
A method for producing a fiber-molded cushion material, comprising performing compression treatment at least once at a compression ratio of 40 to 95%. 2. The method for producing a fiber-molded cushioning material according to claim 1, wherein the low-melting point fiber is made of a thermoplastic elastomer. 3. The method for producing a fiber molded cushion material according to claim 1, wherein a majority of the fiber surface of the low melting point fiber is covered with the thermoplastic elastomer in the fiber cross section. 4. The method for producing a fiber molded cushion material according to claim 2, wherein the polymer constituting the low melting point fiber is a polyester elastomer.