JPH11277558A - Molding method of fiber aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method of fiber aggregate which can curtail a molding time, does not generate packing spots and heat treatment spots, and is capable of mass production with high quality. SOLUTION: In a molding method of fiber aggregate to obtain a cushioning material through a packing process in which the fiber aggregate 1 in which binder fibers are dispersed/mixed is packed into mold cavities C by a conveying air current and a heat treatment process in which finally a molding air current for heating and/or cooling is made to penetrate the aggregate 1, the contact surface between molds 6-8 and the aggregate 1 is partitioned into sections, the flow rate and/or pressures (dynamic pressure and static pressure) of the current passing through each partitioned contact surface W1-W5 are changed corresponding to preset conditions respectively so that the air current in the mold cavity C in the packing process and the heat treatment process is controlled to be suitable for each process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fiber aggregate (hereinafter referred to as "fiber aggregate") in which binder fibers having a lower melting point than the matrix fibers are dispersed and mixed in matrix fibers of synthetic fibers.
The present invention relates to a method for molding a fiber assembly in which a mold cavity is filled with a fiber assembly to form a cushion material after the fiber assembly is filled into a mold cavity for molding.

[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 has problems such as generation of toxic gas at the time of combustion and difficulty in recycling and using it.

[0003] In view of such problems, in recent years, as a material for replacing urethane foam, a cushion material using the above-mentioned fiber aggregate has been attracting attention as a material that can solve these problems. This cushioning material is filled with the fiber aggregate into the cavity of the mold, and by thermoforming this, the binder fibers contained in the fiber aggregate are melted to bond the fibers in the fiber aggregate to each other. It was formed.

[0004] As a method of manufacturing the above cushioning material, a mold is made of a material having air permeability, and a fiber assembly is filled in a mold cavity along with a carrier airflow, and then the fiber filled in the mold cavity is filled. A method of forming a cushion material by flowing heated air and cooled air through the aggregate has been proposed in, for example, JP-A-7-324266. This method has an advantage that the cushion material can be heat-treated quickly and uniformly because the heating material and the cooling air flow through the fiber assembly to thermoform the cushion material.

However, according to the above-mentioned molding method, a cushion material having a complicated shape such as a seat back having a bag structure on an upper portion and having a bent structure on both sides as a backrest of an automobile or the like has excellent quality. There is a problem that a cushion material cannot be obtained. This is because the air flow conditions in the mold cavity required in the process of filling the fiber cavities with the carrier airflow and filling the mold cavities, and the heating air and the cooling air flowing through the fiber aggregates to allow the cushion to flow. This is because the airflow conditions in the mold cavity required in the heat treatment step for molding the material are different. This will be described in detail below.

First, in the step of filling the fiber assembly into the mold cavity, it is said that the fiber assembly must be filled with a predetermined bulk density without causing the fiber assembly to be underfilled in the mold cavity. Conditions are imposed. Therefore, it is necessary to make it easier for the air flow of the fiber assembly to enter the mold cavity where the underfill is likely to occur, so that the portion where the underfill is likely to occur has a higher air permeability of the mold than other portions. There is a need. On the other hand, the forming airflow into the fiber aggregate filled in the mold cavity (in the present invention,
The “forming airflow” and the “heating air and / or cooling air” are used in the same meaning.)
In order not to generate thermoformed spots on the obtained cushioning material,
It is necessary that the molding airflow uniformly and uniformly flow through the mold in a state where the fiber aggregate is filled.

As is clear from the above description, a filling step in which the fiber assembly is gradually filled into the mold cavity, and a heat treatment step in which the fiber assembly is already filled in the mold cavity. Then, the behavior of the air flow in the mold cavity is completely different.

Further, the shape of the mold cavity in the filling step is generally different from that in the heat treatment step unless the molding conditions are so special. Because the bulk density of the fiber aggregate at the time of filling is low, in order to achieve a predetermined bulk density, the mold must be moved in the compression direction to compress the fiber aggregate,
Naturally, this is because the shape of the mold cavity is different between the filling step and the heat treatment step.

As described above, in the filling step and the heat treatment step, the shape of the mold cavity, the flow resistance of the gas flow, the behavior of the gas flow in the mold cavity required in the flow path of the gas flow, and the like differ greatly. I have. In other words, the required characteristics of the behavior of the transport airflow required for transporting the fiber aggregate and the behavior of the forming airflow for converting the fiber aggregate into the cushion material are greatly different. In spite of the great difference in the required properties, the conventional molding method using a mold that does not change the air permeability between the filling step and the heat treatment step avoids the occurrence of uneven spots and uneven heat treatment. Thus, it is extremely difficult to obtain a cushion material of excellent quality.

This is a serious problem in producing a large amount of cushioning material in a short time. because,
In order to prevent uneven heat treatment of the fiber assembly, the heat treatment can be eliminated by slowly raising and lowering the temperature of the fiber assembly over a period of, for example, about 30 minutes. It is too large to be mass-produced, cannot reduce the molding cost, and cannot be adopted at all.

In order to solve the above problem, there is a method of increasing the heat transfer efficiency from the molding airflow to the fiber assembly by flowing a large amount of molding air through the fiber assembly. However, it is necessary to increase the blowing speed of the forming airflow, and the wind pressure increases as the wind speed increases. For this reason, the fiber aggregate that has lost some elasticity due to heating is easily deformed under the influence of large wind pressure,
This causes a problem that the thickness of the obtained product is too small to obtain the desired product thickness, and a cushion material having excellent quality cannot be obtained.

In order to avoid this problem, the speed of the heated air is increased up to a temperature at which the binder fiber softens, and then reduced after the softening, or is reduced during cooling until the fiber aggregate melts or softens. It is also conceivable to increase the cooling rate by cooling with the cooling air at the time when the deformation hardly occurs. Although such a method can certainly reduce the time to some extent, it is still impossible to significantly reduce the heat treatment time required for the temperature raising step and the cooling step. Therefore, in the above method, it is extremely difficult to reduce the molding time to, for example, 5 minutes or less, and it is impossible to reduce the molding cost by mass production while maintaining good quality.

[0013]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the problem to be solved by the present invention is as follows. It is an object of the present invention to provide a method of forming a fiber aggregate for obtaining a cushion material which can be shortened and which is excellent in productivity and quality in which heat treatment unevenness does not occur ".

[0014]

Means for Solving the Problems Here, as means for solving the problems of the present invention, there is provided (claim 1) a fiber aggregate in which binder fibers are dispersed and mixed in matrix fibers composed of synthetic fibers. Through the filling step of filling the mold cavity formed by the air-permeable mold by the heat treatment step of finally flowing the molding airflow for heating and / or cooling into the filled fiber assembly. In the method for forming the obtained fiber assembly, the contact surface between the mold and the fiber assembly is divided into a plurality of sections, and the flow rate and / or the pressure of the airflow flowing through each of the divided contact faces are made to correspond to predetermined conditions, respectively. A method for individually controlling each air flow in the mold cavity during the filling step and during the heat treatment step by changing the air flow. The airflow flowing through each contact surface is controlled by suction and exhaust, and the flow rate of the airflow flowing through each contact surface and / or
Or the method of forming a fiber assembly according to claim 1, wherein the pressure is controlled in accordance with a preset condition, respectively. (Claim 3) In the filling step, a mold cavity in which the fiber assembly is hardly filled is formed. The molding method of a fiber aggregate according to claim 1 or 2, wherein the flow rate of the carrier airflow flowing through the contact surface is controlled to be selectively increased as compared with the other contact surfaces.
(Claim 4) The method for forming a fiber assembly according to any one of claims 1 to 3, wherein the flow rate of the forming airflow is controlled so as to flow over substantially the entire contact surface during the heat treatment step. Provided.

The synthetic fiber material constituting the matrix fiber of the "fiber aggregate" of the present invention is not particularly limited, and may be polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, or polytetramethylene terephthalate. 1,4-
Dimethyl cyclohexane terephthalate, polypivaractone, or a short fiber composed of a copolymer thereof,
Examples include mixed fiber aggregates of these fibers, and short fibers made of a composite fiber (conjugate fiber) composed of two or more of the above-mentioned polymer components.
Further, the cross section of the short fiber may be any of a circle, a flat, an irregular shape and a hollow. Furthermore, it is preferable that the short fibers of the synthetic fibers in this case are provided with crimps, and such crimps are particularly preferably actual crimps. This apparent crimp can be obtained by a mechanical method using a crimper or the like, a method using anisotropic cooling at the time of spinning, a method of heating a side-by-side type or an eccentric sea core type conjugate fiber, or the like.

On the other hand, as the binder fiber, for example, a fiber made of a polymer of a polyurethane elastomer or a polyester elastomer can be exemplified. In particular, a conjugate fiber in which these polymers are exposed on a part of the fiber surface can be suitably used. . It goes without saying that 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.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front cross-sectional view illustrating an apparatus for forming a cushion material by an air blowing method of a fiber assembly for carrying out the method of the present invention. In the figure, 1 is a fiber assembly,
2 indicates a conveyor, 3 indicates an opener, 4 indicates a blower, and 5 indicates a duct. By adopting such an apparatus configuration, air can be blown, and the fiber assembly 1 can be filled into the mold cavity. That is, the fiber aggregate 1 supplied onto the conveyor 2 is sent to the opening device 3 to be opened, and then, along with the transport airflow generated by the blower 4, the mold cavity through the duct 5. Sent to C.

Here, the mold cavity C is provided in the upper mold 6.
, The lower mold 7, and the side mold 8. The upper mold 6 and the lower mold 7 are formed of a gas-permeable material having openings such as a punching plate, and slide on the inner wall surface of the side mold 8 also having gas permeability. Each can move independently. Further, 9 and 11 are exhaust fans, 10 is a blower,
12 is an exhaust pipe, 13 is an air pipe, and 14 and 15
Denotes upper and lower dampers, respectively, and the behavior of the airflow flowing through the mold wall is controlled via these devices.

According to the present invention, the contact surface that comes into contact with the fiber assembly 1 filled with the dies 6 to 7 is divided into a plurality of sections, and the flow rate and / or pressure (dynamic) The main feature is that the air flow in the mold cavity C is controlled by changing the pressure and the static pressure in accordance with preset conditions. Therefore, three contact surfaces W1 to W3 for the upper mold 7 illustrated in FIG. 1, and contact surfaces W for the lower mold 7 and the side mold 8 respectively.
4 and W5, the contact surface (W
1 to W5) are formed. In the example of the apparatus shown in FIG. 1, the lower die 7 and the side die 8 are provided with one contact surface W4 and one contact surface W5, respectively. In some cases, only one contact surface may be provided, or a plurality of contact surfaces may be provided. At this time, when the contact surface is divided into a plurality of sections, the behavior of the airflow flowing through the contact surface can be controlled more finely than in the case where the contact surface is not divided and one contact surface is provided, and the molding conditions are adjusted. A suitable embodiment may be appropriately adopted.

In the apparatus configured as described above, the method of the present invention is divided into a filling step and a heat treatment step with reference to the operation explanatory view of the forming apparatus of FIG. 2 having the same apparatus configuration as that of FIG. This will be described in detail below. 1A shows a preferred behavior of the carrier airflow during the filling step in FIG. 1, and FIG. 2B shows a forming airflow flowing through the compressed fiber aggregate 1 during the heat treatment step. FIG. 4 is a front cross-sectional view showing an example of an embodiment for explaining a preferable behavior of the present invention. However, the fiber assembly 1 shown in FIG.
Is in a compressed state as compared with the state of FIG. That is,
After filling the fiber assembly 1 into the mold cavity C by the filling step of FIG. 1A, the fiber assembly 1 is compressed by moving the upper mold 6 downward to have a predetermined bulk density. In state.

First, the filling step of FIG. 2A will be described. The contact surface W1 where the fiber assembly 1 contacts the upper mold 6 is described.
And the recessed mold cavity C having W3 is not sufficiently filled with the fiber assembly 1. Therefore, the air flow (exhaust amount) from the contact surfaces W1 and W2 is increased so that the fiber assembly 1 is sufficiently supplied to such a portion, and the transport airflow of the fiber assembly 1 is reduced by the contact surfaces W1 and W2. Must be sufficiently discharged from

In order to achieve the above object, FIG.
It is necessary to control the flow rate and / or pressure (dynamic pressure and static pressure) of the carrier airflow under predetermined conditions so that the carrier airflow flows in the direction of the arrow shown in FIG. This control is shown in FIG.
As shown in (1), the upper and lower dampers 14 and 15 can be closed, and the air blower 11 can be operated in this state to exhaust the conveying airflow upward from the upper mold 6 to realize the present invention. At this time, as described above, the upper and lower dampers 14 and 15 are so arranged that the transport airflow is not excessively discharged from the contact surface W5 where the side die 8 and the fiber assembly 1 contact.
Is closed, thereby changing the pressure (static pressure and dynamic pressure) at each contact surface, and increasing or decreasing the flow rate of the conveying airflow to thereby increase the contact surface W.
It is important that the fiber assembly 1 be sufficiently filled in the recessed mold cavity formed by W1 and W3.

Next, when the hollow fiber cavity 1 formed by the contact surfaces W1 and W3 is sufficiently filled with the fiber assembly 1, the air blower 9 is provided substantially opposite to the position where the duct 5 opens. , And the fiber aggregates 1 are successively filled into the mold cavity C from the mold cavity portion near the air blower 9, thereby completing the filling of the mold cavity C. By doing so, the transport airflow can be controlled to a state suitable for the filling step so that the filling unevenness of the fiber assembly 1 does not occur in the mold cavity C.

In the above-described filling step, not only the control by opening and closing the dampers 14 and 15 but also the amount and pressure of the exhaust air from the exhaust fans 9 and 11 are controlled, so that the inside of the mold cavity C is controlled. It goes without saying that the flow rate and / or the pressure (dynamic pressure and static pressure) of the carrier airflow can be controlled under predetermined conditions. Also, the contact surfaces W1 to W
The air permeability of the upper mold 6, the lower mold 7 at the contact surface W4, and the air permeability of the side mold 8 at the contact surface W5 can also be adjusted by changing the opening ratio of the mold, for example. Needless to say, it is possible to provide a suitable air permeability.

When the filling step of the fiber assembly 1 into the mold cavity C is completed, the process proceeds to a heat treatment step shown in FIG. 2B for converting the fiber assembly 1 into the cushion material 20. I do. At this time, the filled fiber assembly 1 is compressed to a state as shown in FIG. (B) by the movement of the upper mold 6 in the compression direction. In the compression of the fiber assembly 1 by the upper mold 6, for example, the upper mold 6 is further divided into a plurality of upper mold members so as to have contact surfaces W1 to W3, respectively. Each of the contact surfaces W1 to W3 may be independently moved downward. In this way, the bulk density of the fiber assembly 1 can be partially controlled so as to have a different bulk density corresponding to the degree of compression of each compression portion of the fiber assembly 1. Further, in order to avoid a problem in thermoforming that the obtained cushioning material 20 cannot obtain a predetermined molding size due to shrinkage or the like during heat treatment, the compression of the fiber assembly 1 is performed only before the heat treatment step is started. Alternatively, it can be performed in multiple stages during or after the heat treatment, and this method provides a cushion material having excellent dimensional stability. Is an effective way to obtain

As described above, the fiber aggregate 1 compressed and controlled to a predetermined bulk density is converted into a cushion material 20 in a heat treatment step, and this heat treatment step is performed by a heating step and a cooling step. Be composed. That is, in the heating step, the heated air is caused to flow through the fiber aggregate 1 to melt the binder fibers in the fiber aggregate 1, and the molten binder fibers have a function as a fusing agent. This is a step of fusing fibers included in the fiber assembly 1 with each other. The cooling step is a step in which cooling air is caused to flow through the fiber assembly 1 to solidify the melted portion and strongly bond the fibers. Through these two steps, the fiber aggregate 1 is converted into a cushion material having a mold shape.

According to the method of the present invention, in such a heat treatment step, the forming airflow flowing through the fiber assembly 1 can be sufficiently controlled. However, as described above, this forming airflow is Since the required behavior is different from the behavior of the conveying airflow, it is important to control the state to a desirable state as the forming airflow.

In the heat treatment step, as shown in FIG.
The fiber aggregate 1 filled in the side wall of the side mold 8, that is, the side of the mold cavity C, has a higher height and a narrower width than that filled in the center of the mold cavity C. Deposited and filled. Therefore, when trying to flow the forming airflow in the vertical direction of the fiber assembly 1, the fiber assembly filled in the central portion of the mold cavity C is caused by the difference in the flow resistance that the forming airflow receives from the fiber assembly 1. As compared with the case of No. 1, there is a problem that the molding airflow does not flow sufficiently into the fiber aggregate 1 filled on the side.

In order to solve the above problem, the contact surface W
Not only from 1 to W3 but also the side mold 8 and the fiber assembly 1
What is necessary is just to make it flow a molding airflow also from the contact surface W5 with this. That is, the flow rate of the forming airflow may be controlled so as to flow on substantially the entire contact surfaces W1 to W5. In the method of the present invention, to realize this, the upper damper 14 is opened and the lower damper 15 is closed, for example, as shown in FIG. By doing so, the flow of the forming airflow can be controlled in the direction indicated by the arrow in FIG. In this case, the forming airflow controlled to a predetermined temperature via a heat exchanger (not shown) is flowed by the blower 10 so as to flow through the fiber assembly 1 from below to above. At this time, since the upper damper 14 is opened and the lower damper 15 is closed, not only the contact surfaces W1 to W3 of the upper mold 6 and the fiber assembly 1 but also the side mold 8 and the fiber The molding airflow is also discharged from the contact surface W5 of the aggregate 1. At this time, the contact surface W1
In order to control the flow rate of the forming airflow flowing through W5 to a desirable value, the optimum flow rate condition is stored in a computer, and the motor rotation of the blower 10 and the exhaust fan 11 is controlled via an appropriate control means such as an inverter. It is also a preferable embodiment to control the amount of air blown by the blower 10 and the amount of air blown by the exhaust fan 11 by changing the number. Further, a flow control means such as a flow control valve or a damper may be provided in the exhaust pipe 12 and the blow pipe 13.

In the above embodiment, the upper damper 1
4, the lower damper 15 is closed, but as another embodiment, the upper damper 14 is closed and the lower damper 15 is opened (the position indicated by the broken line in FIG. (B)). The molding airflow can also flow from the contact surface W5 between the mold 8 and the fiber assembly 1. However, in this embodiment, unlike the previous embodiment in which the molding airflow is discharged from the contact surface W4, the direction of the molding airflow is reversed, and the molding airflow flows into the fiber aggregate 1 from the contact surface W4. Becomes

Further, as still another embodiment, air blow / discharge ducts are independently connected to each of the contact surfaces W1 to W5, and the air blow / discharge ducts are respectively connected to the respective contact surfaces W1 to W5. It is also possible to control the flow rate and pressure of the airflow in the duct. At this time, the contact surface W1 that moves up and down
Needless to say, the duct connected to W3 needs to be a flexible duct such as a telescopic bellows.

[0032]

According to the present invention described above, during the filling step in which the behavior of the transport airflow for transporting the fiber aggregate is important, and in the forming airflow where rapid and uniform heat exchange with the fiber aggregate is required. During the heat treatment step where the behavior is important, it is extremely easy to switch to an airflow behavior suitable for each step. Therefore, even if the cushioning material has a complicated shape, there is no unevenness in filling, and the molding time can be reduced, and at the same time, no unevenness in heat treatment occurs, and it is excellent in mass productivity, low cost molding, and quality. This has an extremely remarkable effect that a cushion material can be obtained.

[Brief description of the drawings]

FIG. 1 is a front sectional view illustrating an air blowing type apparatus to which a molding method of the present invention is applied.

2 (A) is a front sectional view illustrating a preferred behavior of a carrier airflow, and FIG. 2 (B) is a front sectional view illustrating a preferred behavior of a forming airflow flowing through a fiber assembly in a compressed state. It is.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fiber assembly 4 blower 5 duct 6 upper mold 7 lower mold 8 side mold 9 exhaust fan 10 blower 12 exhaust pipe 13 blower pipe 14 upper damper 15 lower damper C mold cavity W1 to W5 contact surface

Claims (4)

[Claims] 1. A filling process in which a fiber assembly in which binder fibers are dispersed and mixed in matrix fibers made of synthetic fibers is filled into a mold cavity formed by a gas-permeable mold by a carrier airflow, and finally, In a method for forming a fiber assembly, in which a cushioning material is obtained by a heat treatment step of flowing a molding airflow for heating and / or cooling into the filled fiber assembly, a contact surface between a mold and the fiber assembly is divided into a plurality of sections. By changing the flow rate and / or pressure of the airflow flowing through each of the divided contact surfaces in accordance with the preset conditions, the airflow in the mold cavity can be changed between the filling step and the heat treatment step. A fiber aggregate forming method, wherein the fiber aggregates are individually controlled. 2. The method according to claim 1, wherein the airflow flowing through each contact surface is controlled by suction and exhaust, and the flow rate and / or pressure of the airflow flowing through each contact surface is controlled in accordance with preset conditions. A method for forming a fiber assembly. 3. The method according to claim 1, wherein in the filling step, the flow rate of the carrier airflow flowing through the contact surface forming the mold cavity where the fiber aggregate is difficult to be filled is controlled to be selectively larger than the other contact surfaces. The method for molding a fiber aggregate according to claim 1 or 2. 4. The flow rate of the forming airflow is controlled so as to flow over substantially the entire contact surface during the heat treatment step.
The method for forming a fiber aggregate according to any one of claims 1 to 3.