JPH07324266A - Production of cushioning material - Google Patents

Abstract

PURPOSE:To obtain a textile cushioning material capable of forming to complicated shape and of obtaining highly cushionable products. CONSTITUTION:A fiber assembly comprising crimped synthetic short fibers and thermoadhesive short fibers having a melting point >=30 deg.C lower than that of the former short fibers at the weight ratio of (30:70) to (90:10) is blown via an opening 3 into molds 1,2 and then compressed so as to be >=100% in compression rate and heated to a temperature lower than the former short fibers but higher than the melting point of the latter fibers and then cooled to a temperature lower than the melting point of the latter fibers to effect adhesive setting of part of the synthetic short fibers with the thermoadhesive short fibers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fiber cushion material, and more particularly to a method for manufacturing a cushion material having a complicated shape, which is suitable for automobiles, office chairs and the like.

[0002]

2. Description of the Related Art As a cushioning material used for automobiles, office chairs, etc., there are used urethane foam, polyester short fiber stuffed cotton, resin cotton or hard cotton to which polyester short fibers are bonded. In particular, urethane foam is often used because it has good durability against a compressive load and can be easily molded into a complicated shape by a molding method or the like.

However, the urethane foam is
It has low breathability and poor moisture and water permeability, so it easily gets damp, and it also has a large feeling of bottoming and is often not preferred as a cushioning material. Further, there are many problems such as difficulty in imparting flame retardancy, generation of toxic gas when burned, and chemicals used during manufacturing causing pollution.

Also, in polyester short-fiber cotton, since the fibers are not fixed, the shape easily collapses during use,
There is a drawback in that the bulkiness and elasticity are greatly reduced due to the movement of fibers and the crimping.

On the other hand, resin cotton or hard cotton to which polyester short fibers are adhered cannot be molded into a complicated shape because the polyester short fibers are fixed by an adhesive or a binder fiber, and the shape of the cushion material is changed. There is a drawback that a large amount of waste is generated when cutting.

By the way, Japanese Patent Laid-Open No. 4-136256 discloses a method of molding a fiber assembly by expanding a fiber assembly in a mold by placing a high-density primary molded body in a mold and heating it. The method of making it proposed is proposed. However, this method requires a step of producing a high-density primary molded body, and in this step, the crimping of the fiber is apt to occur and the cushioning property is deteriorated. Further, since the fiber aggregate is expanded, the product has a low density and the feeling of bottoming becomes large.

[0007]

The object of the present invention is to solve the above-mentioned problems of the prior art, to form a complex shape, and to obtain a product having excellent cushioning properties. It is to provide a method for manufacturing a cushion material.

Another object of the present invention is to provide a method for producing a cushioning material having partially different densities without cutting a fiber molded article or joining with an adhesive.

A further object of the present invention is to provide a method of manufacturing a cushioning material which has a low toxicity of combustion gas at the time of waste incineration, is easy to dispose, and is easy to recycle.

[0010]

The method for producing a fiber cushioning material of the present invention comprises a synthetic short fiber having crimps and a heat-adhesive short fiber having a melting point of 30 ° C. or more lower than the melting point of the fiber (hereinafter,
(A heat-bonding fiber) is blown into a molding die and heated to a temperature below the melting point of the synthetic short fiber and above the melting point of the heat-bonding fiber, and then below the melting point of the heat-bonding fiber. In a method of manufacturing a cushioning material in which synthetic short fibers are partially adhered and fixed by heat-adhesive fibers by cooling to, after blowing the mixed fiber aggregate into a compression molding die, before and after heating At least one of them is characterized in that the mold is closed and the mixed fiber assembly is compressed to increase the density of the mixed fiber assembly by 100% or more.

In the present invention, at least one of the male mold and the female mold of the mold is composed of a plurality of split mold members that are independently movable in the mold closing direction of the mold. At the time of mold closing of the mold, the mixed fiber aggregate is partially compressed at a different ratio by using a mold adapted to make the mold closing force of each split mold member different.
It is also possible to use a cushion material having a partially different density.

In the present invention, the synthetic short fibers are polyester fibers, and the heat-bonding fibers have melting points of 3 with each other.
It is preferable to use a laminated or core-sheath type composite fiber of two-component polyesters that differ by 0 ° C. or more.

Further, in the present invention, a polyester fiber is used as the synthetic staple fiber, and a laminated or core-sheath type composite fiber of polyester and a polyester elastomer having a melting point lower than the melting point of the polyester by 30 ° C. or more is used as the thermal bonding fiber. It is more preferable to use.

The present invention will be described in detail below with reference to the drawings. 1 and 2 show vertical cross sections of examples of molds used in the present invention, the molds are not limited to these, and various molds can be used without departing from the spirit of the present invention. Shaped molds can be used. In the description of the drawings, the top and bottom of FIGS. 1 and 2 are referred to as the top and bottom, and the left and right are referred to as the left and right.

In FIG. 1, a male mold (1) and a female mold (2) are integrally formed. On the right side of the female mold (2), an opening (3) for blowing the fiber assembly is formed. In Fig. 1, the male type (a) indicated by the chain double-dashed line shows the male type (1) at the position when the fiber assembly is blown through the opening (3), and the male type (b) indicated by the solid line. Shows the male mold (1) in the position when the fiber assembly is compressed. The openings (3) may be formed at arbitrary positions depending on the shape of the mold, but when the mold has a complicated shape, it is preferable that the openings are formed at a plurality of locations. Further, it is preferable that the opening is formed at a position where the hole is closed by the other mold when the mold is closed.

In FIG. 2, the female mold (12) of the mold is integrated, and the male mold (11) is composed of three split mold members (11A) (11B) (11C). The female mold (12) is similar to that shown in FIG.
2) An opening (13) for blowing the fiber assembly is formed on the right side. Split mold members (11A) (11B) (11
C) is movable independently in the vertical direction, and when the mold is closed, each split mold member (1
The mold closing force of 1A) (11B) (11C) can be made different. Further, as in the case of FIG. 1, the male type (a) represented by the chain double-dashed line shows the male type (11) at the position when the fiber assembly is blown from the opening (13) and is represented by the solid line. The male type (b) is
Figure 7 shows the male mold (11) in position when compressing the fiber assembly.

At least a part of the mold is made of a material having air permeability. As such a material, for example, a punching plate, a porous ceramic or the like is suitable. In the case of a punching plate, it is preferable that a mesh plate or the like is attached to the inner surface of the plate in order to prevent the fibers from being blown out from the punch portion of the punching plate when the fiber assembly is blown.

The fiber assembly used in the present invention is a mixture of crimped synthetic short fibers and heat-bonded fibers having a melting point lower than the melting point of the fibers by 30 ° C. or more. If the melting point difference is less than 30 ° C., the properties of the synthetic short fibers may be deteriorated in the heat treatment step described later, and a high-performance cushion material may not be obtained. If possible, there is a melting point difference of 50 ° C. or more. More preferable.

As the crimped synthetic short fibers, polyester fibers, polyamide fibers, polypropylene fibers and the like can be used, but polyester fibers are preferable from the viewpoint of durability of the cushioning material. Specifically, as the polyester fiber, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, polyethylene naphthalate, polyarylate, or the like, or a copolymerized ester fiber composed of monomers constituting these polyesters can be exemplified. . Furthermore, from the viewpoint of elasticity, polyester fibers provided with a coil-shaped three-dimensional crimp are more preferable. The cross-sectional shape of the synthetic short fibers may be circular, irregular, or hollow, and the thickness thereof is preferably in the range of 4 to 200 denier. If the thickness of the single fiber is less than 4 denier, the density of the cushioning material must be increased to obtain the required hardness, and the elasticity decreases. Further, if the thickness of the single fiber exceeds 200 denier, the number of fiber constituents of the cushion material decreases, and it becomes impossible to mold it into a complicated shape.
Further, in the present invention, it is also useful to mix two or more kinds of fibers.

As the above-mentioned heat-bonding fibers, conventionally known thermoplastic synthetic fibers such as polyolefin fibers, modified nylon fibers, modified polyester fibers, etc., and a laminated type of these polymers with other polymers, or a core-sheath. Thermobonded fibers, such as moulded composite fibers, can be used. When the heat-adhesive fiber is composed of one component, the hardness of the cushioning material cannot be sufficiently obtained in many cases, so that the heat-adhesive component occupies 50% or more of the surface, a bonding type of two or more components, or a core. Sheath type conjugate fibers are preferred as the heat-bonding fibers.

As such a heat-bonding fiber, a composite fiber composed of a polyethylene terephthalate component and a copolyester component having a melting point of 30 ° C. or more lower than that is preferable from the viewpoint of adhesiveness and durability.

Polyester elastomers are also useful as the heat-adhesive component. Polyester elastomer is a thermoplastic polyester hard segment,
It is a polyester ether copolymer having a polyalkylene diol as a soft segment or a polyester ester copolymer having an aliphatic polyester as a soft segment. In the present invention, as the heat-bonding fiber, a composite fiber of polyethylene terephthalate and a polyester elastomer having a melting point lower by 30 ° C. or more than the melting point of the polyethylene terephthalate is more preferable from the viewpoint of cushioning property and durability. By using the polyester-based elastomer as the heat-adhesive component in this manner, since the formed adhesive portion has rubber elasticity, elasticity and durability against compression are significantly improved.

Specific examples of preferable combinations of these synthetic short fibers and thermal bonding fibers include: synthetic short fibers: polyethylene terephthalate and thermal bonding fibers: composite fibers of polyethylene terephthalate and low melting point copolyester, synthetic short fibers: polyethylene. Terephthalate and heat-bonding fiber: A composite fiber of polyethylene terephthalate and polyester elastomer can be used.

As described above, by using all polyester fiber materials as the cushion material, the toxicity of the combustion gas at the time of incineration of the cushion material is reduced, so that the disposal is facilitated and the recycling is facilitated.

In the present invention, the mixing ratio of the synthetic short fibers and the heat-bonding fibers constituting the fiber assembly is such that the cushion material 1
The range of 10 to 70% by weight of the heat-bonding fiber is preferable with respect to 00% by weight, and the range of 30 to 60% by weight is more preferable. If the thermal bonding fiber is less than 10% by weight, the cushion material is likely to lose its shape because there are few bonding points, and if the thermal bonding fiber is more than 70% by weight, the ratio of the crimped synthetic short fiber is reduced and the elasticity is reduced. Is not suitable as a cushioning material.

In the method for producing the cushioning material of the present invention, the synthetic short fibers having crimps and the heat-bonding fibers can be mixed by a known method, but after being roughly mixed with a blender or the like, the mixture is further homogenized. Can be mixed. This latter mixing is preferably performed using a roller card, a random weber or the like, which has excellent openability. If the mixing is not carried out uniformly, the unevenness of the number of adhesion points between the fibers increases the hardness unevenness of the cushion material, and the shape easily collapses. Further, if the fiber openability is poor, a large number of aggregates of fibers will be present, and the comfort of the cushioning material will be poor.

In the present invention, it is preferable to use an air flow to blow the fiber assembly into the mold. The fleece spun from a roller card or the like is directly sucked or is once taken out as a fiber aggregate and then blown into a mold by a blow nozzle. When blowing into the mold, for example, the male mold (1) in FIG. 1 is held at the position (a). After blowing a predetermined amount of the fiber aggregate, the male mold (1) is lowered to the position (b) to compress the fiber aggregate and increase the density of the fiber aggregate by 100% or more. With no compression or a density increase of less than 100%, in order to blow the fiber aggregate in an amount necessary for obtaining an optimum density as a cushioning material,
A very high-pressure air flow is required, and even if it is blown in, the density unevenness becomes large. Preferred density increase is 30
It is about 0 to 800%.

Next, the fiber assembly in the mold is heated to a temperature below the melting point of the synthetic short fibers and above the melting point of the heat-bonding fibers. This heating may be carried out by heating a mold in which a heater is embedded, but it is better to pass the gas at the above temperature through the fiber assembly in the mold, because the thermal efficiency is better,
It is preferable because the temperature can be raised to the inside of the fiber assembly in a short time. In this case, use a mold made of breathable material. For example, place the female mold (2) on the suction box (40) as shown in FIG. From inside the suction box (40) to create a negative pressure in the suction box (40). Allow heated gas to penetrate the body (4). Conversely, the male mold (1) side may be sucked and the heated gas may be supplied from the female mold (2) side.
Furthermore, it is also effective to put the entire mold in a vacuum oven, suck air between the fiber assemblies (4) in the die, and then blow heated gas into the vacuum oven. By the heat treatment, the adhesive component of the heat-bonding fibers is melted, and the synthetic short fibers and the heat-bonding fibers and the intersections of the heat-bonding fibers are partially bonded.

This heating step can be carried out before the above-described compression step of the fiber assembly, or after the fiber assembly has been compressed to some extent, it can be heated and then compressed.

When using synthetic staple fibers having a large apparent heat shrinkage, it is preferable to heat and then compress.
When compression is performed first and after heating to the final molded shape,
In some cases, the fiber assembly may be further shrunk and a predetermined shape may not be obtained. On the other hand, when using a heat-bonding fiber having a large apparent heat shrinkage rate, it is preferable to perform heating after compression or to perform two-stage compression before and after heating.
Under a low binding force, the heat-adhesive fibers contract, easily enter the inside of the fiber assembly, the ratio of the heat-adhesive fibers on the surface is apparently reduced, and the surface strength of the cushioning material is weak and fluffing easily occurs. Therefore, it is necessary to select the most suitable method according to the properties of the fiber used.

After compression and heating, the fiber assembly in the molding die is cooled to a temperature below the melting point of the heat-bonding fiber. This cooling is
As in the case of heating, it is preferable to perform it by a method in which a gas having the above temperature is passed through the fiber assembly in the mold. By the cooling treatment, the melted adhesive component of the heat-bonded fiber is solidified,
The intersections between the synthetic short fibers and the heat-bonding fibers and between the heat-bonding fibers are firmly bonded.

[0032]

The present invention will be described in more detail with reference to the following examples. [Example 1] Polyethylene terephthalate short fibers with a hollow cross section having a three-dimensional denier of 13 denier (melting point 256 ° C) as synthetic short fibers, and 4-denier core-sheath type polyester-based composite short fibers as thermal bonding fibers (trade name, Eslanal E) (sheath component flow starting temperature 123 ° C.) was used. These synthetic short fibers and heat-bonded fibers were mixed in a blender at a ratio of 7: 3, and a fiber aggregate was obtained using a roller card. This fiber assembly was blown into a molding die (1) (2) made of a punching plate shown in FIG. 1 by an air flow through an opening (3). At this time, the male mold (1) is held at the position (a). Next, the male mold (1) was moved downward and the fiber assembly was compressed so that the compression ratio was 100%. After compression, as shown in FIG. 3, 170 ° C. air was passed through the mold for 3 minutes to heat the fiber assembly, and then air at room temperature was passed through for 1 minute to be cooled to obtain a cushion material. The compression rate of the above fiber assembly is defined by the following equation. Fiber assembly compression rate (%) = {(mold internal volume before compression-mold internal volume after compression) / mold internal volume after compression} x 100

The average density and density unevenness of the obtained cushioning material were measured as follows. <Average Density> Average Density of Cushion Material (g / cc) = Weight of Cushion Material / Volume of Cushion Material <Density unevenness> 10 cm x 10 c from the entire cushion material
A rectangular parallelepiped of m × 3 cm (thickness) was cut out as much as possible, the density of each rectangular parallelepiped was measured, the maximum density, the minimum density and the average density of the rectangular parallelepiped were calculated, and calculated by the following formula.
(In this example, 16 rectangular parallelepipeds could be cut out.) Density unevenness of cushion material (%) = {(maximum density-minimum density) / average density} x 100

Further, the evaluation of the molding shape of the obtained cushion material was visually classified into the following four stages. ⊚: The shape of the mold is good and the finish of the edge is sharp. ○: The shape of the mold is the same, but the edge is slightly sagging. Δ: There are some recessed portions on the edge compared to the shape of the mold. : Compared to the shape of the mold, the edge has a large recessed portion. The above results are shown in Table 1.

[Examples 2 to 4] The compressibility of the fiber assembly was
A cushioning material was obtained in the same manner as in Example 1 except that compression was performed so as to be 300% (Example 2), 500% (Example 3), and 800% (Example 4), respectively. Table 1 shows the evaluation of the average density, the density unevenness, and the molding shape of the obtained cushioning material.

[Comparative Examples 1 and 2] The compressibility of the fiber assembly was
A cushioning material was obtained in the same manner as in Example 1 except that the material was compressed or not compressed to 50% (Comparative Example 1) or 0% (Comparative Example 2). Table 1 shows the evaluation of the average density, the density unevenness, and the molding shape of the obtained cushioning material.

The cushion materials obtained by the methods of Examples 1 to 4 had good average density, little density unevenness, and excellent molding shape. On the other hand, the cushion material of Comparative Example 1 had large density unevenness and was slightly inferior in molding shape. Further, the cushion material of Comparative Example 2 had a larger density unevenness and had a very poor molding shape.

[0038]

According to the method of the present invention, after blowing the fiber assembly into the mold, and before and / or after heating, the mold is closed to compress the mixed fiber assembly, Since the density of the mixed fiber aggregate is increased by 100% or more, it is easy to blow, the cushion material can be molded into a complicated shape, and a product having excellent cushioning properties can be obtained. Further, in a preferred case of the present invention, in which at least one of the male mold and the female mold is composed of a plurality of split mold members, in a preferred case of the present invention, the fiber molded product is partially cut without cutting or joining with an adhesive. It is possible to easily manufacture cushioning materials having different densities.

[0039]

[Table 1]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a mold used in the present invention.

FIG. 2 is a vertical cross-sectional view showing an example of a mold used in the present invention.

FIG. 3 is a diagram for explaining a method of passing a heating gas through a fiber assembly in a mold.

[Explanation of symbols]

(1) (11)… Male type of mold (11A) (11B) (11C)… Three split mold members constituting the male mold (11) (2) (12)… Female mold of the mold (3) ( 13)… Blown holes for blowing fiber assembly (a)… Position of male mold (1) when blowing fiber assembly (b)… Position of male mold (1) when compressing fiber assembly ( 4) Fiber assembly (30) Hot air stove (31) Heated and cooled gas inlet (40) Suction box (41) Suction port

Claims (4)

[Claims] 1. A melting point of a synthetic short fiber, which is obtained by blowing a fiber assembly in which a synthetic short fiber having a crimp and a thermoadhesive short fiber having a melting point lower than the melting point of the fiber by 30 ° C. or more are mixed into a molding die. Heated below and above the melting point of the heat-adhesive short fibers,
Then, in a method of manufacturing a cushioning material in which synthetic short fibers are partially adhered and fixed by heat adhesive short fibers by cooling to a temperature equal to or lower than the melting point of the heat adhesive short fibers, a mixed fiber assembly is compressed into a mold. After being blown in, at least one of before heating and after heating, the mold is closed to compress the mixed fiber assembly so that the density of the mixed fiber assembly is 100.
%, Or more, and a method for manufacturing a fiber cushion material. 2. At least one of a male die and a female die of a mold is composed of a plurality of split mold members that are independently movable in a mold closing direction of the mold, and these split mold members are made of a mold. At the time of mold closing, the mixed fiber assembly is partially compressed at different ratios by using a mold adapted to make the mold closing forces of the split mold members different from each other, and a cushioning material having a partially different density. The method for producing a fiber cushion material according to claim 1, wherein: 3. A synthetic short fiber, a polyester fiber, and a heat-adhesive short fiber having different melting points of 30 ° C. or more.
The method for producing a fiber cushion material according to claim 1 or 2, wherein a laminated or core-sheath type composite fiber of the component polyester is used. 4. A laminated or core-sheath type composite fiber of polyester fiber as the synthetic short fiber, and polyester and a polyester elastomer having a melting point of 30 ° C. or more lower than the melting point of the polyester as the heat-adhesive short fiber. The method for producing a fiber cushion material according to claim 1 or 2, characterized in that.