JP3945899B2 - Method for forming fiber assembly - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a fiber assembly in which binder fibers having a melting point lower than that of a matrix fiber are dispersed and mixed in a matrix fiber made of synthetic fibers (hereinafter simply referred to as “fiber assembly”) is thermoformed into a cushion material. At this time, the present invention relates to a method for filling a fiber assembly, in which the fiber assembly filled in a mold cavity is thermoformed while being controlled to a predetermined bulk density.
[0002]
[Prior art]
In general, inexpensive urethane foam has been widely used as a cushioning material for seats having complicated shapes such as automobiles and aircraft. However, since urethane foam has problems such as generation of toxic gas at the time of combustion and difficulty in recycle use, an alternative molding material has been eagerly desired.
[0003]
Because of these problems, in recent years, cushion materials using the above-described fiber assembly as a material for replacing urethane foam have attracted attention as materials that can solve these problems. This cushion material is formed by filling a fiber assembly into a cavity of a mold and melting the binder fiber contained in the fiber assembly by thermoforming it to bond the fibers in the fiber assembly. It is formed.
[0004]
As a method of manufacturing the cushion material, the mold is made of a material having air permeability, the fiber aggregate is filled in the mold cavity along with the conveying air flow, and then the fiber aggregate filled in the mold cavity is filled. For example, Japanese Laid-Open Patent Publication No. 7-324266 proposes a method of forming a cushion material by causing heating air and cooling air to flow through. Compared to the conventional method of filling mold cavities using automated machines such as hand lay-ups and robots, this method thermo-molds the cushioning material by allowing heating air and cooling air to flow through the fiber assembly. Therefore, there is an advantage that the cushion material can be heat-treated quickly and uniformly.
[0005]
However, in such a conventional molding method, when trying to mold a cushion material having a complicated shape such as a seat back that becomes a backrest of an automobile or the like having a bag structure at the top and a bent structure on both sides. The following problems occur.
[0006]
That is, in the method of filling the fiber assembly into the mold cavity using an automated machine such as a hand layup or robot, partly control the bulk density of the fiber assembly in order to obtain a cushioning material with excellent sitting comfort. Then, it is necessary to fill a fiber assembly whose bulk density is adjusted in advance corresponding to each part of the required mold cavity. For this reason, it is required to prepare a fiber assembly having a bulk density adjusted corresponding to each part of the mold cavity and place it on each part of the determined mold cavity. For this reason, in the method of adjusting the predetermined bulk density corresponding to each part of the mold cavity, it takes time for the preparation step to partially adjust the bulk density of the fiber assembly, shortening the molding time, Or it is difficult to reduce the molding cost.
[0007]
Further, in the method of filling the mold cavity with the fiber aggregate accompanying the conveying airflow (hereinafter referred to as “air blowing method”), the bulk density can be controlled corresponding to each part of the mold cavity. difficult. In particular, the fiber assembly is filled in a mold cavity C (a region surrounded by the upper mold 1, the lower mold 2, and the side mold 3) having a narrow standing wall portion 7 as shown in FIG. In this case, it is difficult to blow and fill the standing wall portion 7 without lacking the fiber assembly.
[0008]
Furthermore, even if such a standing wall portion 7 can be filled with the fiber assembly without excess or deficiency, in the conventional fiber assembly molding method in which the upper mold 1 is moved downward and compressed in the up and down direction, The above-described compression of the standing wall portion 7 is not sufficiently performed as compared with other portions, and it is difficult to control to a fiber assembly having the required bulk density. For this reason, in the cushion material 10 obtained by completing thermoforming as shown in FIG. 4, a predetermined hardness is applied to a D portion (indicated by hatching in the drawing) corresponding to the standing wall portion 7 of the mold cavity C. Can not have.
[0009]
[Problems to be solved by the invention]
In view of the above-mentioned problems, the problem to be solved by the present invention is “for preparing a fiber assembly corresponding to each part of a mold cavity with respect to a mold cavity having a complicated shape. It is an object of the present invention to provide a method for forming a fiber assembly that can be easily packed by filling the bulk density of the fiber assembly to a predetermined bulk density without requiring a preparation step.
[0010]
[Means for Solving the Problems]
Here, as means for solving the problems of the present invention, “filling a fiber assembly in which binder fibers having heat-fusibility are dispersed and mixed in a matrix synthetic fiber into a mold cavity having a standing wall portion, and filling In the method for forming a fiber assembly, the fiber assembly is obtained by compressing the fiber assembly in the vertical direction to adjust the bulk density and finally thermally bonding the fibers together with the binder fiber to obtain a cushioning material. The fiber assembly filled in the mold cavity is further compressed against the standing wall portion from the side, thereby controlling the fiber assembly to a predetermined bulk density. Is provided.
[0011]
In the above-described method of the present invention, it is preferable to adopt a method in which a fiber assembly is accompanied by a conveying air flow and conveyed to the mold cavity when filling the mold cavity with the fiber assembly.
[0012]
Here, the synthetic fiber material constituting the matrix fiber of the “fiber assembly” of the present invention is not particularly limited, and polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly 1, Short fibers made of 4-dimethylcyclohexane terephthalate, polypivalactone, or a copolymerized ester thereof, a mixed fiber assembly of these fibers, or a composite fiber (conjugate fiber) made of two or more of the above polymer components, etc. The short fiber which consists of can be illustrated. Further, the cross-sectional shape of the short fiber may be any of a circular shape, a flat shape, an irregular shape, and a hollow shape. Furthermore, it is preferable that crimps are imparted to the short fibers of the synthetic fiber in this case, and as such crimps, it is particularly preferable that the crimps are manifest. This actual crimping can be obtained by a mechanical method using a crimper or the like, a method using anisotropic cooling during spinning, a method of heating a side-by-side type or eccentric sea core type composite fiber, or the like.
[0013]
On the other hand, examples of the binder fiber include fibers made of a polyurethane-based elastomer or a polyester-based elastomer polymer. Particularly, a composite fiber in which these polymers are exposed on a part of the fiber surface can be preferably used. Needless to say, an appropriate amount of the binder fiber is dispersed and mixed in the matrix fiber in accordance with the required performance of the product to be molded.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail together with the operation thereof with reference to the drawings.
[0015]
1 and 2 are front sectional views illustrating a mold for carrying out the method of the present invention.
In the figure, 1 is an upper mold, 2 is a lower mold, 3 is a mold frame, 4 is a left mold, 5 is a right mold, and reference numeral 6 shown by a two-dot chain line (imaginary line) Indicates each inlet. Here, the mold frame 3 itself also serves as a side mold in the front and rear direction (perpendicular to the paper surface of FIGS. 1 and 2). Therefore, the mold cavity C is formed by the inside of the region surrounded by the upper mold 1, the lower mold 2, the mold frame 3, and the left and right side molds 4 and 5. The upper mold 1 and / or the lower mold 2 are configured to be movable in the vertical direction, and the fiber assembly (not shown) filled in the mold cavity C can be compressed in the vertical direction. Further, the left side mold 4 and the right side mold 5 are configured to be movable in the left and right directions, respectively, so that the fiber assembly filled in the mold cavity C can be compressed in the left and right side directions.
[0016]
In the mold for molding the cushion material 10 configured as described above, a method of filling the fiber assembly into the mold cavity C may be, for example, an air blowing method or a hand lay-up. Accordingly, the method for filling the fiber cavity into the mold cavity C need not be particularly limited, but the air blowing method is used to fill the fiber cavity with the fiber aggregate in carrying out the method of the present invention. The time can be shortened compared with other methods, which is preferable. This is because, according to the air blowing method, for example, the mold is completely opened and the fiber assembly (usually in the form of a web shaped in advance) is placed in the mold cavity, and then the mold This is because a process such as closing can be omitted.
[0017]
In addition, when filling the fiber assembly into the mold cavity C by the air blowing method, it is generated by a blower or the like (not shown) from the blowing port 6 indicated by a two-dot chain line in FIGS. The transported air flow is accompanied by a small fiber aggregate and blown into the mold cavity C. In the embodiment shown in the figure, the blowing port 6 is provided on the front side or the rear side of the mold frame 3 so as to open to the mold frame 3. Hereinafter, the method of the present invention will be described by the air blowing method.
[0018]
In the air blowing method, the mold is formed of a gas-permeable material having an opening such as a punching plate, and the fiber assembly is conveyed to the mold cavity along with the conveyance airflow. It is preferable to quickly discharge from the mold cavity through the mold. In addition, as another advantage of using the air-permeable mold in this way, when the fiber assembly filled in the mold cavity is converted into the cushion material 10 by the heat treatment process, the fibers are passed through the mold. A heating airflow or a cooling airflow can be allowed to flow into the aggregate, and heating and cooling of the fiber aggregate can be made uniform.
[0019]
In order to fill the mold cavity C by the air blowing method, it is important to expand the shape of the mold cavity as a preparatory step from the position where the final shape is formed on the cushion material 10. This will be described with reference to the embodiment illustrated in FIG. 1. The mold cavity C is arranged such that the upper mold 1, the left mold 4, and the right mold 5 are positioned as shown in FIG. Move to and be greatly expanded. At this time, the standing wall portion 7 shown in FIG. 1 is expanded in the left-right direction by moving the left-side mold 4 and the right-side mold 5 in the left-right direction. Therefore, unlike the conventional method in which a narrow standing wall shape as shown in FIG. 3 has to be adopted, the method of the present invention makes it possible to secure a wide path for the conveying air current, so that the conveying air current is sufficiently high. It is possible to penetrate the portion 7 and to sufficiently supply the fiber aggregate to the standing wall portion 7 without excess or deficiency.
[0020]
When the fiber assembly is filled in the mold cavity C in this manner, the fiber assembly is then compressed to the shape shown in FIG. 2 in order to adjust and control the fiber assembly to a predetermined bulk density. . The method of the present invention is characterized by compressing the fiber assembly filled in this compression step not only in the vertical direction but also from the side. By such a method, not only the bulk density of the fiber assembly in the front-rear direction but also the bulk density of the fiber assembly in the left-right or front-rear direction can be controlled to a predetermined value for the first time. That is, by the method of the present invention, it is possible to achieve for the first time by compressing from the side the bulky high density control that cannot be achieved only by the compression from the vertical direction of the standing wall portion 7 that extends long in the vertical direction. It is.
[0021]
At this time, with respect to the shape when the mold cavity C is enlarged, the hardness and softness required for each part of the cushioning material 10 to be molded, the air permeability, etc. from the shape of the mold cavity when the final shape cushioning material 10 is obtained. It goes without saying that the compression ratios are set corresponding to the compression ratios in the front and rear, left and right, and up and down directions according to the characteristics.
[0022]
The fiber assembly compressed as described above and controlled to a predetermined bulk density is converted into the cushion material 10 in the heat treatment step, and this heat treatment step is constituted by a heating step and a cooling step. . That is, in the heating step, heating air is passed through the fiber assembly to melt the binder fiber in the fiber assembly, and the melted binder fiber has a function as a fusion agent. This is a step of fusing fibers contained in the aggregate. The cooling step is a step of causing the cooling air to flow into the fiber assembly to solidify the melted portion and firmly bond the fibers together. Through these two steps, the fiber assembly is converted into a cushion material 10 in which the mold shape is accurately shaped.
[0023]
The fiber assembly may be compressed vertically or laterally as the first stage compression before the heat treatment of the fiber assembly begins, or in multiple stages during or after the heat treatment. You can also Such multi-stage compression is preferable for obtaining a cushioning material excellent in heat shrinkage and thermal stability when the fiber assembly is converted into a cushioning material having a predetermined shape, and further, the mold shape is changed. It is also preferable for obtaining an accurately shaped cushion material.
[0024]
Moreover, according to the method of the present invention, not only the air blowing method but also other methods such as the hand lay-up method, the fiber assembly is preliminarily molded to the characteristics required for each part of the cushion material, and the bulk is increased. It is not necessary to go through a preparation step for adjusting the density. In other words, after preparing a fiber assembly having a uniform bulk density and filling it in the mold cavity, the fiber assembly is predetermined by simply moving each mold and compressing the fiber assembly. It is also possible to adjust and control locally to a high density.
[0025]
【The invention's effect】
According to the present invention described above, “fibers can be prepared without preparing a fiber assembly corresponding to each part of the mold cavity for a mold cavity having a complicated shape. It is possible to provide a method for forming a fiber aggregate that can be easily packed by adjusting the bulk density of the aggregate to a predetermined bulk density.
[Brief description of the drawings]
FIG. 1 is a front sectional view of a mold illustrating a state of a mold cavity when a fiber assembly is filled.
FIG. 2 is a front sectional view of a mold illustrating a state of a mold cavity when compression of a fiber assembly is completed.
FIGS. 3A and 3B are front sectional views of a mold for explaining a conventional method, wherein FIG. 3A shows a state when the fiber assembly is filled, and FIG. 3B shows a state when the filling of the fiber assembly is completed. Show.
4 is a perspective view illustrating a cushion material obtained by molding using the mold of FIG. 3. FIG.
[Explanation of symbols]
1 Upper mold 2 Lower mold 3 Mold frame 4 Left mold 5 Right mold 6 Blowing port 7 Standing wall C Mold cavity

Claims (2)

Filling a mold cavity with a standing wall with a fiber assembly in which binder fibers having heat-fusible properties are mixed in the matrix synthetic fiber, and compressing the filled fiber assembly in the vertical direction to adjust the bulk density. while, finally by heat fusion of the fibers by the binder fibers in the molding process of the fiber aggregate to obtain a cushion material, wherein the further side of the filled fiber aggregate into the mold cavity having a standing wall portion A method of forming a fiber assembly, wherein the fiber assembly is controlled to a predetermined bulk density by compressing the standing wall portion . 2. The method of forming a fiber assembly according to claim 1, wherein when the fiber assembly is filled in the mold cavity, the fiber assembly is transported to the mold cavity along with the transport airflow.

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