JPH09111628A - Molding of cushion material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cushion material free from wrinkles and strains and excellent in quality, when an inner layer and a fiber aggregate surrounding the inner layer are thermally molded. SOLUTION: This method for molding the cushion material comprises molding as a cushion material a fiber aggregate comprising an inner layer in which thermoplastic elastic short fibers are dispersed and blended in a matrix comprising a non-elastic crimped short fiber aggregate, and an outer layer which surrounds the inner layer and in which thermoplastic elastic short fibers or the mixture of the thermoplastic elastic short fibers with one or more kinds of flame-resistant crimped short fibers and flame-retardant crimped short fibers are dispersed and blended in a matrix comprising a non-elastic crimped short fiber aggregate. Therein, the molding of the fiber aggregates constituting the inner layer and the outer layer in molds (1 and 2) comprises temporarily molding only a fiber aggregate (4) constituting the outer layer to form the outer shape of the cushion material, charging a fiber aggregate constituting the inner layer into the molded outer layer and subsequently thermally molding the combination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushioning material for seats of automobiles, airplanes, etc., and a method for molding a cushioning material used for furniture, bedding and the like.

[0002]

2. Description of the Related Art In recent years, with the advancement of lifestyles, cushioning of furniture, bedding (particularly, beds for nursing homes and hospitals), cushions for seats of various transportation facilities, etc. has become flame-resistant or difficult from the viewpoint of safety. Flammability has come to be required. In particular, regarding seat cushions for aircraft, it is the first priority to protect the precious lives of passengers from fire, etc., and therefore extremely strict flame-retardant standards are determined by the Federal Aviation Administration of the United States (FAA) standards. Is a well-known fact.

As a cushioning material that meets the above conditions, WO94-03393 proposes a cushioning material having a two-layer structure composed of an outer layer fiber structure surrounding an inner layer fiber structure. Here, with respect to the fiber structure forming the inner layer and the outer layer of the cushion material,
This will be briefly described below.

First, as the fiber structure constituting the outer layer,
One or more kinds of "flame-resistant crimped short fibers" together with "thermoplastic elastic short fibers" in some cases, in a matrix composed of fiber aggregates composed of "non-elastic crimped short fibers". And / or "flame-retardant crimped staple fiber"
Including. 2) is dispersed and mixed, and a part of the entanglement points of the "thermoplastic elastic short fibers" and other fibers are heat-sealed, and thus a fibrous structure is used.

The fiber structure constituting the inner layer may be composed of the same kind of fiber aggregate as the fiber structure constituting the outer layer, but the fiber composed of the above-mentioned "non-elastic crimped short fibers". "Thermoplastic elastic short fibers" were dispersed and mixed in the matrix composed of the aggregate, and a part of the entanglement points between the "thermoplastic elastic short fibers" and the "non-elastic crimped short fibers" were heat-sealed. Fibrous structures are used to reduce costs.

Here, examples of the above "non-elastic crimped short fibers" include polyester fibers and meta-aramid fibers. The "thermoplastic elastic short fibers" have a melting point lower than that of "non-elastic crimped short fibers" by 60 ° C or more, and are eccentric sheath-core type composites composed of thermoplastic elastomer and non-elastic polyester. A fiber etc. can be mentioned. Furthermore, examples of the "flame-resistant crimped short fibers" include fibers obtained by subjecting polyacrylonitrile fibers to flameproofing treatment (preoxidized), and examples of the "flame-retardant crimped short fibers" include phosphorus-based or halogen-based fibers. Examples thereof include polyester fibers obtained by copolymerizing or blend-polymerizing the above compound, and the above-mentioned meta-aramid fibers.

By the way, regarding the method for molding the above-mentioned fibrous structure having a two-layer structure, this is also described in WO94.
-03393 only discloses a method in which a fiber assembly composed of an inner layer is surrounded by a fiber assembly constituting an outer layer in advance, and the fiber assembly is placed in a cavity of a mold and thermoformed. This method will be briefly described with reference to FIGS. 1 and 2.

FIG. 3 shows a mold for molding a fiber assembly, which comprises an upper mold (10) and a lower mold (20).
The mold is provided with a cavity (C ′) for filling the fiber assembly as shown in FIG. 4 and shaping it into the cavity shape, and for thermoforming. . In addition, in the cavity (C ′), the fiber aggregates (4a to 4d and 4e and 4f) forming the outer layer,
The fiber aggregates (3a to 3c) forming the inner layer are placed with their shapes shaped as shown in FIG. 4, respectively. Then, in this state, the upper mold (10) and the lower mold (2
0) is overlaid and heated in this state to obtain a cushion material having a predetermined shape. In addition,
In FIG. 4, the fiber aggregates (4e and 4f) installed on the front side and the back side of the figure are not shown.

However, in such a molding method, when the cavity shape of the mold becomes complicated, the fiber assembly is smoothly shaped into the mold cavity shape in the process of filling the cavity with the fiber assembly composed of the inner and outer layers. As a result, wrinkles and distortions often occur in the molded product (fibrous structure) after molding. For this reason,
The fiber assembly must be placed with great care so that wrinkles and distortion are not generated, but wrinkles and distortion often occur even with such close attention. Therefore, it has been strongly desired to improve this process in order to obtain a molded product having excellent quality.

[0010]

DISCLOSURE OF THE INVENTION In order to solve the above problems and obtain a cushioning material having excellent flame retardancy or flame resistance, the present invention provides a fiber assembly having a two-layer structure consisting of inner and outer layers. It is an object of the present invention to provide a molded product on the market in which wrinkles and molding distortion are extremely small when molded into a complicated shape.

[0011]

According to the present invention, an inner layer in which thermoplastic elastic short fibers are dispersed and mixed in a matrix composed of non-elastic crimped short fiber aggregates and an inelastic crimped short fiber aggregates. A thermoplastic elastic short fiber in the matrix consisting of, or an outer layer surrounding the inner layer in which one or more kinds of flame-resistant crimped short fibers and / or flame-retardant crimped short fibers are dispersed and mixed together with the thermoplastic elastic short fiber; In a method of molding a fiber assembly comprising a cushion material as a cushioning material, the fiber assembly constituting the outer layer is temporarily molded to shape the outer shape of the cushioning material after molding, and the inner layer is formed inside the shaped outer layer. Provided is a method for molding a cushion material, which comprises filling the fiber assembly and then integrally molding the outer layer and the inner layer to obtain a cushion material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings.

1 and 2 are perspective views illustrating a part of a temporary molding apparatus for a fiber assembly constituting an outer layer for carrying out the molding method of the present invention. In the figure, 1 is an upper mold,
2 is a lower mold, 4 is a fiber assembly constituting the outer layer, 5 is a fluid pressure operated cylinder, 6 is a hot air blowing port, 7 is a hot air exhaust port,
Reference numeral 8 denotes a temporary molding apparatus main body, and C denotes a mold cavity.

In the temporary molding apparatus configured as described above, the upper mold (1) and the lower mold (2) are made of a material having air permeability (for example, made of stainless steel in which a large number of holes are perforated). Plate, wire mesh, etc.).

Here, the upper mold (1) is fitted to the lower mold (2) by moving downward by the fluid pressure actuated cylinder. Therefore, as shown in FIG. 2, the fiber assembly (4) forming the outer layer is placed between the upper and lower molds,
Sandwiching between the upper and lower molds, the shape of the cushion material which is the final molded product is shaped. As shown in FIG. 3, in the case of the box type, as shown in FIG. 3, the shaping process of the fiber assembly (4) forming the outer layer is performed by adding six shaped fiber assemblies each in the upper, lower, front, back, left and right directions. You may go to. However, in such a shaping process, the molding cost rises due to the equipment investment required for the shaping process, the complexity of the work, and the like.

Therefore, if necessary, for example, the fiber aggregate constituting the outer layer is shaped into a sheet, and the sheet is drawn to be shaped into a box-like shape with an open upper portion. Needless to say, the lower part, the front-rear part, and the left-right part can be shaped at once except for the upper part.

Next, the shaping effect of the fiber assembly will be briefly described below.

In the fiber assembly of the present invention, the "thermoplastic elastic short fibers" are dispersed and mixed in the "inelastic crimped short fibers" which are the main constituent fibers at the time of thermoforming. When heated above the melting point of the "fiber" and below the melting point of the "non-elastic crimped short fiber", the fibers are thermally fused (heat-bonded) at the entanglement point of the "thermoplastic elastic short fiber", whereby the short fiber Movement is restricted to form a fibrous structure. Moreover, the fiber structure molded in this way is
Since the entanglement points are three-dimensionally distributed by point fusion (point adhesion), there are many voids between fibers having a two-dimensional shape, which makes them extremely breathable and bulky. It has the property of being excellent.

Here, the molding conditions for the cushioning material of the present invention are as follows: the outer layer is first preliminarily molded and shaped, and then the inner layer is surrounded by the outer layer for main molding. In the processing, it is preferable to perform molding and shaping under conditions milder than those in the main molding. For example, it is preferable that the time required for temporary molding is shorter than the time required for main molding, or that the molding temperature is lower during temporary molding than during main molding.

Therefore, in FIG. 1 and FIG. 2, hot air having a temperature higher than the melting point of the thermoplastic elastic short fibers and lower than the melting point of the inelastic crimped fibers (in the direction of the arrow shown) is supplied to the hot air supply port ( 6) Supply from. At this time, since the upper die (1) and the lower die (2) are made of a material having air permeability, the hot air flows through the lower die (2) to form an outer layer fiber assembly. Heat fusion (thermal adhesion) occurs at the point where the thermoplastic short fibers of the fiber assembly are entangled by the heat supplied to the body and received at this time. Then, the hot air for generating heat fusion is discharged from the upper mold (2) also made of a gas permeable material through the exhaust port (7). The hot air may be exhausted outside the apparatus as it is, but it is preferable to circulate it from the viewpoint of energy saving.

Finally, it can be preferably used as the "non-elastic crimped short fibers", "thermoplastic elastic short fibers", "flame-resistant crimped short fibers" and "flame-retardant crimped short fibers" used in the present invention. The details are shown below.

As the "non-elastic crimped short fibers" constituting the outer layer used in the present invention, aramid fibers and polyester fibers are preferably used. For example, as the non-elastic polyester crimped short fibers, usual polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly 1,4-dimethylcyclohexane terephthalate, polypivalolactone, or copolymerization thereof is used. Examples thereof include short fibers made of ester, a blended body of these fibers, and a composite fiber made of two or more kinds of the above polymer components. In order to improve the flame retardancy and heat resistance of these polyester fibers, it is particularly preferable to use those obtained by copolymerizing or blending phosphorus-based or halogen-based compounds. Further, the cross-sectional shape of the short fibers may be circular, flat, irregularly shaped or hollow.

Further, the crimp in this case is preferably an actual crimp, and the actual crimp is a mechanical method such as a crimper, an anisotropic cooling method during spinning, a side-by-side type or an eccentric sheath core. It can be obtained by a method such as heating the type composite fiber.

On the other hand, as "thermoplastic elastic short fibers",
For example, a composite fiber formed of a thermoplastic elastomer such as a polyurethane elastomer or a polyester elastomer and an inelastic polyester, which has a melting point of 60 ° C. or more lower than that of the “inelastic crimped short fiber” forming the matrix is preferably used. can do. In this case, if the difference in melting point is less than 60 ° C., the “thermoplastic elastic short fibers” are likely to deteriorate during heat treatment, which is not preferable.

As the "thermoplastic elastic short fibers", a thermoadhesive polymer is arranged on a sheath / core type (or side-by-side type) composite fiber sheath (one side in the side-by-side type), It is also known that the core (the other side in the side-by-side type) is provided with a high melting point polymer constituting a matrix fiber. As the sheath-core type composite fiber made of the “thermoplastic elastic short fiber” used in the present invention, an eccentric core portion is preferable because a coil-shaped elastic crimp is developed.

Next, as the "flame-resistant crimped short fibers", those having a weight residual ratio of 35% or more by the flameless test method are preferable. For example, polyacrylonitrile fibers or crosslinked phenolic fibers are subjected to air oxidation treatment (flame resistance). (Treated) flame-resistant fiber (pre-oxydized fiber), carbon fiber obtained by completely carbonizing the flame-resistant fiber, and polybenzimidazole (PBI) fiber. Furthermore, pitch-based carbon fibers that have been infusibilized using pitch refined from coal or petroleum and then carbonized can be preferably used.

The weight residual ratio by the above flameless test method is measured as follows.

An electric heater is installed in a cubic box of 50 cm on a side, and 1 g of the sample is placed in the container in the center so that the sample to be measured does not melt and drip.
A thermal decomposition treatment is performed at 750 ° C. for 4 minutes. At that time, the temperature is detected by a thermocouple installed on the sample mounting stage, and as a weight residual rate, a difference (W-W) between the weight of the measurement sample before thermal decomposition (W) and that after thermal decomposition (W ') is detected. ′) Is measured and (W
-W ') is divided by W, and this is expressed in percentage.

Finally, examples of the "flame-retardant crimped short fibers" that can be preferably used in the present invention include polyester fibers and aramid fibers. When polyester fibers are used, those obtained by copolymerizing or blending phosphorus-based or halogen-based compounds are preferable in order to improve their flame retardancy and heat resistance.

[0030]

As described above, according to the present invention, when thermoforming a fiber assembly comprising an inner layer and an outer layer surrounding the inner layer,
The occurrence of wrinkles and distortion is extremely reduced, and therefore, there is an extremely large effect that a cushion material of excellent quality can be provided to the market.

[Brief description of the drawings]

FIG. 1 is a perspective view of a molding apparatus of the present invention.

FIG. 2 is a front view of the molding apparatus of the present invention.

FIG. 3 is a perspective view illustrating a mold for temporary molding of the outer layer fiber assembly used in the present invention.

FIG. 4 is an explanatory view showing a conventional thermoforming method.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 4 Outer layer fiber assembly 5 Fluid pressure operated cylinder 6 Hot air exhaust port 7 Hot air supply port 8 Device body

Claims (1)

[Claims] 1. An inner layer in which thermoplastic elastic short fibers are dispersed and mixed in a matrix composed of non-elastic crimped short fiber aggregates, and thermoplastic elastic short fibers in a matrix composed of non-elastic crimped short fiber aggregates, or In a method for forming a cushioning material, a fiber assembly comprising thermoplastic elastic short fibers together with one or more kinds of flame-resistant crimped short fibers and / or flame-retardant crimped short fibers dispersed and mixed, and an outer layer surrounding the inner layer , Temporarily shape the fiber assembly that constitutes the outer layer, shape the outer shape of the cushion material after molding, fill the inside of the shaped outer layer with the fiber assembly that constitutes the inner layer, and then integrate the inner layer and the outer layer A method for forming a cushion material, which comprises forming the cushion material.