JP4010578B2 - Molding method for fiber assembly - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a method for forming a fiber assembly in which a binder fiber having a melting point lower than that of a short fiber is dispersed and mixed in a matrix composed of short fibers of a synthetic fiber having a crimped form. The present invention relates to a mold filling method for filling a body (a cotton lump, hereinafter also referred to as “cotton” or “cotton lump”) into a mold cavity.
[0002]
[Prior art]
In general, urethane foam has been frequently 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 recycling, a molding material to replace this has been eagerly desired.
[0003]
Because of these problems, in recent years, as a material for replacing urethane foam, a fiber assembly in which binder fibers having a melting point lower than the short fibers are dispersed and mixed in a matrix composed of short fibers of synthetic fibers having a crimped form. A fiber structure using a body has attracted attention as a material that can solve the above problems. This fiber structure is obtained by filling cotton into a cavity of a mold and heat-bonding the binder fibers contained in the cotton by thermoforming.
[0004]
Conventionally, as a method for filling cotton into a cavity of a molding die, for example, a lump of cotton is temporarily shaped into a certain size, and the shaped cotton is hand-packed or molded by an automatic machine such as a robot. The method of filling into the mold has been adopted. However, this method requires temporary shaping of the cotton once and then stuffing the preliminarily shaped cotton into the cavity of the mold. There is a problem that a temporary storage place for installing the shaped cotton is also required.
[0005]
In order to solve such a problem, a method of pneumatically transporting cotton into a shaping die as a lump of cotton without temporarily shaping cotton is disclosed in, for example, Japanese Patent Publication No. 56-29556 and Japanese Patent Publication No. 62-29069. And Japanese Utility Model Publication No. 1-272727. In this method, after a cotton lump is formed by the spreader, the cotton lump coming out of the spreader is guided into the mold cavity together with the air flow generated by the blower, and the gold lump is conveyed by pneumatic transport. This is a method of filling the mold cavity with cotton.
[0006]
However, this mold filling method has been found to have the following serious problems when the fiber assembly is thermoformed into a fiber structure.
[0007]
That is, the fiber assembly is made into a cotton lump by a spreader, but considering the cotton lump itself at this time, in the lump, the fibers are entangled with each other. When the binder fibers are fused by thermoforming, they have a strong binding force with each other. However, as for the contact surface where the cotton lumps are in contact with each other, the entanglement between the fibers is not formed, so the binding force of only the part where the binder fibers contained in the adjacent cotton lumps melt and adhere There is only. For this reason, as a matter of course, the bonding strength at the contact surface between adjacent cotton lumps is weaker than other portions.
[0008]
Furthermore, in the filling of cotton by pneumatic transportation into the mold cavity, the cotton lumps are sequentially laminated in parallel along the surface from the cavity surface of the mold through which the air flow flows. Therefore, parallel layered arrangement surfaces (lamination surfaces) appear along the cavity surface of the mold. In such a layered arrangement surface, the bonding force between the surfaces is only the bonding force caused by the fusion of the binder fibers that are in contact with each other as described above. It becomes weaker than the binding strength of. For this reason, the strength of the bonding force of the fiber structure obtained by thermoforming is significantly different between the direction along the array surface of the fiber assembly and the direction perpendicular to the array surface. For such reasons, the thermoformed fiber structure has a problem that it tends to lose its shape.
[0009]
However, the appearance of the layered arrangement surface described above is fateful as long as the method of sequentially transferring the cotton lumps to the mold cavity by pneumatic transport and laminating and filling them as described above. Therefore, there is a need for a method for filling a fiber assembly that can eliminate the problem.
[0010]
[Problems to be solved by the invention]
In view of the above-described problems, the problem to be solved by the present invention is to fill cotton mold cavities by pneumatic transport without passing through an extra process such as a temporary shaping process that increases the cost of molding. It is to provide a fiber assembly mold-packing method that can skillfully eliminate the fatal defect that the fiber structure after thermoforming has a flawless bond strength while adopting this method. .
[0011]
[Means for Solving the Problems]
Here, according to the present invention, in order to thermoform a fiber assembly in which a binder fiber having a melting point lower than that of the short fiber is dispersed and mixed in a matrix composed of short fibers of a synthetic fiber having a crimped form, ventilation is performed. In the method of filling the fiber assembly opened into a cavity of a mold made of a functional member by pneumatic transportation,
After the fiber assembly is packed in the cavity of the mold, an array surface (hereinafter referred to as “array surface (P) ” ) that forms a layer of fiber assemblies formed in parallel along the surface of the cavity of the mold A method of filling a fiber assembly, characterized by repeatedly applying compression and decompression to the fiber assembly from a direction along the arrangement plane (P) .
[0012]
Further, in the present invention, when forming the layered arrangement surface (P) , an air flow that flows from the inside of the mold cavity made of the air-permeable member to the outside of the mold is generated in the local portion. by locally substantially parallel layered arrangement surface of the surface layer portion of the fiber aggregate air flow is in contact with a mold portion which is then generated along the mold surface (P ') of the array surface (P) and the Forming it separately and performing the randomization on the array surface (P) is preferable in terms of improving the tear strength of the surface layer portion of the fiber structure.
[0013]
Here, as the air-permeable member constituting the mold, a member having a large number of holes perforated like a punching plate can be preferably used. Moreover, you may use the material which has air permeability, such as a porous sintered metal and a wire mesh, and these combination. The material at this time is preferably a metal such as stainless steel, but needless to say, it may be a heat-resistant resin or ceramic. Furthermore, after forming the basic skeleton of the mold, a woven or knitted fabric may be bonded to the basic skeleton with a metal or resin woven fabric or the like.
[0014]
For these breathable members, in order to control the packing density of cotton in the mold, the number, size, distribution density of holes, etc. corresponding to these packing densities May be changed to change the air permeability of each part of the mold.
[0015]
In addition, as a fiber assembly suitable for this invention, what is listed below is preferable.
[0016]
First, the synthetic short fibers constituting the matrix of the fiber assembly are not particularly limited. For example, ordinary polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly 1, Preferred are short fibers made of 4-dimethylcyclohexane terephthalate, polypivalolactone, or a copolymerized ester thereof, a blend of these fibers, or a composite fiber made of two or more of the above polymer components. . Moreover, the cross-sectional shape of the short fiber may be any of a circle, a flat shape, an irregular shape, and a hollow shape.
[0017]
Further, the crimp in this case is preferably an actual crimp, and this actual crimp is a mechanical method using a crimper or the like, a method using anisotropic cooling during spinning, a side-by-side type or an eccentric sea core type composite fiber. It can obtain by the method by the heating.
[0018]
On the other hand, as the binder fiber, for example, a polyurethane-based elastomer or a polyester-based elastomer may be mixed according to the required performance of the product to be molded.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the present invention described above will be described in detail below with reference to the drawings.
[0020]
FIG. 1 is a front cross-sectional view illustrating a conventional mold filling method by pneumatic transportation. In the figure, F is a small lump of cotton, 1 is a mold formed into a predetermined shape by a breathable member such as a punching plate (perforated plate), and the mold (1) is: It consists of an upper mold (1a) and a lower mold (1b), and these upper mold (1a) and lower mold (1b) are used to fill and thermoform a small piece of cotton (F). A cavity (C) is formed for this purpose. Reference numeral 2 denotes a pneumatic transport duct for supplying a small piece of cotton (F) to the mold (1). In addition, 1c shows the "back side" position where the cotton lump (F) of the mold (1) is filled first. The definitions of these symbols are the same in FIGS. 2 and 3 described later.
[0021]
In the mold (1) configured as described above, a small piece of cotton (F) is filled into the cavity (C) of the mold (1) by pneumatic transportation via the duct (2), Then, the air flow accompanied with the cotton lump (F) flows out from the upper and lower molds (1a) and (1b) having air permeability to the outside of the mold (1). At this time, the small pieces of cotton (F) that have been pneumatically transported are sequentially filled from the back side (1c) of the mold (1). For this reason, the cotton lumps (F) are deposited from the back side (1c) while being sequentially layered as shown in FIG. 1, and as indicated by the thin two-dot chain line in the figure, A layered arrangement surface (P) is formed. As described above, when such an array surface (P) is formed, a difference occurs in the binding force between the direction along the array surface (P) and the direction perpendicular thereto.
[0022]
FIG. 2 is a front cross-sectional view illustrating the mold filling method of the present invention for solving the above problem. In the figure, (A) shows a state in which a small piece of cotton (F) is packed in the cavity (C) of the mold (1) by pneumatic transportation. Since the cotton lump previously packed on the back side (1c) is compressed by the cotton lump that has been subsequently packed, the packing density is high.
[0023]
From such a state, as shown in FIG. (B), an arrangement surface (a layer of cotton lumps (F) formed in parallel along the surface of the cavity (C) of the mold (1) ( P) is repeatedly compressed and decompressed to the cotton blob (F) in the direction of the arrow in the figure, that is, along the arrangement plane (P), and the arrangement plane (P) is randomized. . Needless to say, such compression and decompression movements can be realized by repeatedly moving the upper die (1a) in the direction of the arrow in FIG.
[0024]
In FIG. 2, only the upper mold (1a) is repeatedly moved in the direction of the arrow in (B). However, the present invention is not limited to this mode. For example, the lower mold (1b) Instead, it goes without saying that the upper mold (1a) may be moved repeatedly or the upper and lower molds (1a) and (1b) may be moved simultaneously. In short, as shown in Fig. (A), avoid the formation of the layered arrangement surface (P) in the cotton blob (F), and (B) the orientation of the layered arrangement surface as explained with reference to the figure. It is important to randomize so that it has no directionality.
[0025]
The cotton blob (F ′) in which the arrangement surfaces (P) arranged in layers in this manner are randomized is then clamped, and the binder fibers are heat-sealed by heating with circulating hot air, for example. The fiber structure. Then, for example, after cooling the fiber structure and the mold by blowing cold air into the cavity of the mold, the upper mold (1a) is lifted to open the mold (1), thereby the mold (1) A single molding cycle is completed by taking out the fiber structure from.
[0026]
Next, FIG. 3 shows a front sectional view for explaining another embodiment of the present invention, and this embodiment will be described in detail with reference to the drawing.
[0027]
In the figure, a mold (1) made of a breathable member has an air flow (air flowing in the direction of the arrow in the figure) flowing from the inside of the cavity (C) of the mold (1) to the outside of the mold. (Not shown) for locally generating a flow) is locally connected in contact with the mold (1). In addition, as a means for generating this local air flow, for example, a blower, a vacuum pump, or the like is used, and the mold (1) and these means are connected by a duct, through which the duct is connected. This can be realized by sucking air.
[0028]
Wherein the Figure 3 shows a state like that caused the air stream flowing through the inside to the outside of the cavity (C) of the mold (1) to below the lower mold (1b).
[0029]
In such an embodiment, the surface portion of the cavity (C) of the mold (1) selectively sucked by the aforementioned suction means (not shown) is substantially parallel to the surface of the mold (1) . A layered arrangement surface (hereinafter referred to as “layered arrangement surface (P ′ ) ” ) different from the layered arrangement surface (P) described in FIG. 1 and FIG. 2 can be formed. Along with this and the progress of the formation of the layered arrangement surface (P) in the suction part, a small piece of cotton transferred into the cavity (C) of the mold (1) by pneumatic transportation is transferred to the mold (1 also it becomes to be sequentially stacked from the back side (1c) of), whereby it is possible to realize a stacked state of nodules cotton as shown in Figure 3.
[0030]
In this way, when the filling of the small piece of cotton into the cavity (C) of the mold (1) is completed, the cavity of the mold (1) is moved by the movement of the upper mold (1a) as described above. The layered arrangement surface (P) of the inner layer part of (C) is randomized and thermoformed.
[0031]
As described above, along the surface of the cavity (C) of the mold (1), the cotton blob (F1) should form a parallel and selective layered arrangement surface (P ' ). The significance of this is that the in-plane surface tear strength can be improved without having directionality in the fiber structure. And thereby, the remarkable effect that the fiber structure excellent in the tear strength of the surface layer part of the fiber structure can be obtained will be exhibited.
[0032]
【The invention's effect】
As described above, according to the present invention, an extra process such as a temporary shaping process that increases the cost of molding is not employed. Moreover, in the present invention, while adopting a method of filling cotton into the mold cavity by pneumatic transportation, this method is substantially different from the arrangement surface with respect to the formation of the layered arrangement surface that is fatal. By repeatedly applying compression and decompression in a direction perpendicular to the surface, the arrangement surface can be disturbed, and this can solve the fatal defect that the bonding force on the arrangement surface of the fiber structure after thermoforming is weak. There is an extremely remarkable effect.
[0033]
In addition, there is an extremely remarkable effect that the in-plane tear strength can be selectively increased only in the surface layer portion of the fiber structure.
[Brief description of the drawings]
FIG. 1 is a front sectional view of a mold for explaining a conventional mold filling method by pneumatic transportation.
FIG. 2 is a front sectional view for explaining an embodiment of the mold filling method of the present invention.
FIG. 3 is a front sectional view for explaining another embodiment of the mold filling method of the present invention.
[Explanation of symbols]
1 Mold 1a Upper mold 1b Lower mold 2 Air transport duct F Fiber assembly (cotton)
P arrangement surface

Claims (2)

In order to thermoform a fiber assembly in which a binder fiber having a melting point lower than that of the short fiber is dispersed in a matrix composed of short fibers of a synthetic fiber having a crimped form, the inside of a cavity of a mold made of a breathable member In a method of filling the fiber assembly opened into a mold by pneumatic transportation,
After the fiber assembly is packed in the cavity of the mold, the array surface is arranged with respect to the array surface (P) that forms a layer of fiber assemblies formed in parallel along the surface of the mold cavity. A method of filling a fiber assembly, characterized by repeatedly applying compression and decompression to the fiber assembly from the direction along (P) . When forming the array surface (P) , a local air flow is generated by locally generating an air flow that flows from the inside of the mold cavity made of the air-permeable member to the outside of the mold. was the surface layer portion of the fiber assembly in contact with the mold part the separately formed from the array surface (P) substantially parallel layered arrangement surface (P ') along the mold surface, the array surface (P) 2. The fiber assembly die-packing method according to claim 1, wherein the randomization is performed on the fiber assembly.

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