JPH1149316A - Molding method of cushion structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To favourably absorb deformation and contaction of a molded article by compressing a fiber aggregate up to a state leaving a compression flap of a specific range rather than a final compressed position, finishing a heating process thereafter and compressing the fiber aggregate to the final compressed position while a cooling process is finished. SOLUTION: A fiber aggregate 1 dispersing and mixing binder fiber having a lower melting point than short fiber in a matrix consisting of wound and contracted short fiber of synthetic fiber is fed to a fiber opening machine 2 and opened, transferred in the inside of a transfer duct 4 on an air current supplied from an air blower 3, molded and closed in a mold cavity C, and thereafter, the binder fiber is melted by circulating hot air in the fiber aggregate. Before starting such a heating process, the fiber aggregate filled in the mold cavity C is compressed to a state leaving a compression flap of 5-50 mm rather than a final compressed state, and thereafter, the fiber aggregate 1 is compressed to the final compressed state while the heating process is finished and a cooling process is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for filling a mold cavity with a fiber assembly in which a binder fiber having a melting point lower than that of a crimped short fiber is dispersed and mixed in a matrix composed of crimped short fibers of synthetic fibers. The present invention relates to a method for forming a cushion structure by thermoforming in a mold cavity to obtain a cushion structure.

[0002]

2. Description of the Related Art Inexpensive urethane foams have been widely used as cushioning materials for seats having complicated shapes such as automobiles and aircraft. However, urethane foam generates toxic gases when burned. In addition, there is a problem that it is difficult to use it for recycling. For this reason,
An alternative cushioning material has been desired.

[0003] Due to such problems, molded articles obtained from fiber aggregates have recently been receiving attention as a material for replacing urethane foam. Here, the fiber aggregate is obtained by dispersing and mixing binder fibers having a melting point lower than that of the short fibers in a matrix composed of short fibers of synthetic fibers. And, a molded product of this fiber aggregate has attracted attention as a material capable of solving the above-mentioned problems. This molded product is filled in a mold cavity with an air flow accompanying the opened fiber assembly, as proposed in Japanese Patent Application Laid-Open No. 62-152407, and thermoformed. can get. That is, the fibers are formed by thermally fusing the fibers in the fiber assembly at their intersections with the binder fibers contained in the fiber assembly.

However, when mass production and cost reduction are required as in a cushion structure for an automobile, it is required to shorten the molding time required for the heating step and the cooling step in order to shorten the molding cycle. You. For this reason, in order to shorten the heating time, it is essential that a high-speed and large amount of heated air flow through the fiber assembly filled in the mold cavity in the heating step. However, the heated fiber assembly has significantly lost elasticity as compared with a state where the fiber assembly is kept at a normal room temperature, and is deformed by the wind pressure. . In addition, since the binder fiber is deformed while being melted, there is a problem that the dimensional stability of the obtained cushion structure is poor. Further, the fiber aggregate generally has a property of causing heat shrinkage of 3 to 5%, and therefore, there is a problem that a smaller size product is formed than a molded product having the intended size. I have.

[0005] For this reason, it is conceivable to suppress the wind speed of the heated air. Indeed, according to this method, problems such as thermal shrinkage of the fiber assembly can be solved. However, for example, when heating at a low wind speed in accordance with these required characteristics, it takes 10 minutes or more to heat the fiber assembly to a predetermined temperature. Therefore, shortening the molding cycle is not considered at all, and reduction in molding cost cannot be expected.

[0006]

In view of the above-mentioned problems, the objects of the present invention are as follows. That is, the object of the present invention is to solve the drawbacks of the conventional method such that the intended shape of the molded article and the required dimensional stability cannot be obtained due to deformation of the molded article due to heated air or shrinkage during thermoforming. And
An object is to provide a method by overcoming these disadvantages.

[0007]

According to the present invention, a fiber assembly in which binder fibers having a melting point lower than that of short fibers are dispersed and mixed in a matrix composed of crimped short fibers of synthetic fibers is used in a mold. The mold is packed into the cavity, and then a heating step of flowing hot air through the fiber assembly to melt the binder fibers, a melting step of fusing the fibers of the fiber assembly at the intersection thereof, and a cooling air flow In the molding method of performing a cooling step of solidifying the melted binder fibers to obtain a cushion structure, before the start of the heating step and / or during the heating step, the fiber aggregate is moved 5 to 5 degrees from the final compression position. The fiber assembly is compressed to a state where a compression allowance of 50 mm remains, and then the fiber assembly is compressed to a final compression position before the heating step is completed and the cooling step is completed. Molding process of the cushion structure characterized is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The material of the crimped short fibers of synthetic fibers constituting the matrix of the fiber aggregate of the present invention is not particularly limited. However, for example, short fibers made of polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, polypivaractone, or copolymerized esters thereof, and mixed fiber aggregates of these fibers A body or a composite fiber (conjugate fiber) composed of two or more of the above polymer components is suitable. Further, the cross-sectional shape of the short fiber may be any of a circle, a flat, an irregular shape, and a hollow. Further, in this case, it is preferable that the crimp applied to the short fibers of the synthetic fibers is an actual crimp. This apparent crimp can be obtained by a mechanical method using a crimper or the like, a method using anisotropic cooling during spinning, a method using heating a side-by-side type or eccentric sea core type composite fiber, and the like.

On the other hand, as the binder fiber, for example, a polyurethane-based elastomer or a polyester-based elastomer fiber, in particular, a conjugate fiber in which these polymers are exposed on a part of the fiber surface can be suitably used. An appropriate amount of the binder fiber is dispersed and mixed in the matrix fiber according to the required performance of the product to be molded.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view schematically illustrating an apparatus for performing the method of the present invention. In the figure, 1 is a fiber assembly, 2 is an opening machine, 3 is a blower, 4 is a transfer duct, 5 is a forming mold, 6 is an upper mold having air permeability, 7 is a lower mold having air permeability, 8 is an upper mold actuator, 9 is a lower mold actuator, 10
Is an exhaust chamber, 11 is an exhaust fan, 12 is a heating air supply device, 1
Reference numeral 3 denotes a cooling air supply port, reference numeral 14 denotes an exhaust fan for heating air and cooling air, and reference numeral C denotes a mold cavity.

In the apparatus configured as described above,
As shown in (a), the fiber assembly 1 is sent to the opening device 2 and spread, and is transferred in the transfer duct 4 along with the air flow supplied from the blower 3 to be supplied to the mold cavity C. Is done. The mold cavity C is a space formed by the molding frame 5, the upper mold 6, and the lower mold 7, and the space is filled with the fiber assembly 1 and thermoformed. At this time, the transport airflow that transports the fiber assembly 1 supplied to the mold cavity C is exhausted from the exhaust chamber 10 by the exhaust fan 11. When the mold cavity C is filled with the fiber assembly 1 in this manner, the process proceeds to the next step.

In this step, as shown in FIG. 2B, the upper mold 6 and the lower mold 7 are respectively moved up and down by an actuator, and the fiber assembly filled in the mold cavity C by a predetermined amount is moved. One can start by compressing one.
However, this compression may be performed during the heating step described below.

In this heating step, a heated air flow is supplied from a heating air supply device 12 in the direction of the arrow shown in FIG.
It starts by flowing the fiber assembly filled in the mold cavity C and melting the binder fibers in the fiber assembly. At this time, it goes without saying that the air blower 14 is operating. In this way, the fibers in the fiber assembly are bonded together at the intersection with the binder fiber.

At this time, what is important in the method of the present invention is that the fiber assembly filled in the mold cavity C is moved 5 to 50 mm from the final compression position before and / or during the heating step. This means compressing to the state where the compression allowance is left. By heating the fiber aggregate in such a state, the fiber aggregate is thermoformed, and the fiber aggregate gradually starts to contract as the temperature of the fiber aggregate itself increases. Eventually, heat shrinks to a shape smaller than the accommodated mold cavity. In addition,
The heat shrinkage increases as the bulk density of the fiber aggregate decreases, and decreases as the bulk density increases. Further, it is needless to say that the above-mentioned compression allowance of the present invention is set to be equal to or more than the clearance amount finally generated between the fiber assembly and the mold due to such heat shrinkage.

Further, in the heating step, it is preferable that the heated air flow through the fiber assembly from below the mold cavity to above the mold cavity in a direction against gravity. because,
This is because, in the heating step, deformation due to the weight of the fiber aggregate is added in addition to the wind pressure of the heated air, and the heat shrinkage is further increased.

Next, as shown in FIG. 3C, the fiber assembly is further compressed to the final compression position by the time the heating step is completed and the cooling step is completed, thereby crushing the compression allowance. Very important. This is because by performing this step, the above-mentioned clearance generated between the mold and the heat-shrinked molded product can be eliminated for the first time. Further, by doing so, even if heat shrinkage occurs in the molded product, the mold shape can be accurately transferred to the molded product. Then, the dimensional stability of the obtained molded product is extremely improved, and a cushion structure having desired characteristics and shape can be molded as intended. The cooling air at this time is generated by operating the exhaust fan 14 to take in the cooling air at room temperature from the cooling air supply port and to flow through the fiber assembly.

The above-mentioned compression allowance may be appropriately selected and used according to the performance of the cushion structure to be thermoformed. However, it is not preferable that the compression allowance exceeds 50 mm, because the fiber aggregate moves from a predetermined position, and the bulk density unevenness and bloody flesh occur due to the influence of the wind pressure of the heated air. If it is less than 5 mm, it is difficult to transfer a mold having a desired shape, and the dimensional stability after molding is deteriorated.

[0018]

As described above, according to the present invention, the deformation of the molded product due to the heated air and the shrinkage during thermoforming can be favorably absorbed, and the shape of the mold can be accurately and as intended. It has an extremely remarkable effect that it can be transferred. In addition, the molded article obtained by the method of the present invention has excellent dimensional stability.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view schematically illustrating an apparatus for explaining a method of forming a cushion structure according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber aggregate 2 Spreader 3 Blower 4 Transfer duct 5 Mold frame 6 Upper die 7 Lower die 8, 9 Actuator 10 Exhaust chamber 11 Exhaust air 12 Hot air supply device 13 Cooling air supply port 14 Exhaust air

Claims (2)

[Claims] 1. 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 crimped short fibers of a synthetic fiber, is filled into a mold cavity. A heating step of causing the hot air to flow through to melt the binder fibers, a melting step of fusing the fibers of the fiber assembly at the intersection thereof, and a cooling step of flowing the cooling air to solidify the melted binder fibers, respectively. In the molding method for obtaining the cushion structure by applying, before the start of the heating step and / or during the heating step, the fiber assembly is compressed to a state leaving a compression allowance of 5 to 50 mm from the final compression position, Wherein the fiber aggregate is compressed to a final compression position before the heating step is completed and the cooling step is completed. . 2. The method of molding a cushion structure according to claim 1, wherein, in the heating step, heated air flows from below the mold cavity to above the mold cavity in a direction against gravity.