JPH0795971B2 - Method of molding polyurethane sheet pad - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for molding a polyurethane sheet pad used for a seat of an automobile, and the like.
The present invention relates to a method for molding a polyurethane sheet pad in which a bank portion having different hardness is formed on both sides of the seat portion or a peripheral portion of the seat portion.

[Prior Art and Problems to be Solved by the Invention] In recent years, as a method of manufacturing a seat for an automobile or the like, a method of covering a polyurethane sheet pad (stuffing) having a bank on both sides of a seat with a skin material has been proposed. It is widely used, and in this case, the polyurethane sheet pad having a uniform hardness as a whole is also used, but a bank portion different hardness urethane sheet pad in which the hardness of both bank portions is higher than the hardness of the sitting portion is used. It is preferably used from the standpoints of improving the supportability and improving the appearance of the upholstery material.

Conventionally, a method shown in FIGS. 13 and 14 is known as a method for manufacturing the above-mentioned bank portion different hardness polyurethane sheet pad.
That is, in the method shown in FIG. 13, a weir plate d is projected on a boundary between a center portion b corresponding to the seat portion of the cavity and side portions c and c corresponding to the bank portion in the mold a, Liquid A, which is a foaming raw material for obtaining a foam having a low hardness, is injected into the part b, and liquid B, which is a foaming raw material for obtaining a foam having a high hardness, is injected into both side parts c and c to foam these. Is the way. In addition, the method shown in FIG. 14 is such that, in the mold a of FIG. 13, metal partition plates e, e are provided on the bottoms of both side parts c, c, respectively.
Or the partition plates e, e made of foamed resin are arranged, and the liquid A is injected into the inside of the partition plates e and e, and the liquid B is injected into the outside to perform foaming. When a metal partition plate is projected, this partition plate is removed from the pad after foaming, and when a foam resin partition plate is used, this partition plate sticks to the polyurethane foam and remains on the pad. Is.

However, the above-mentioned conventional methods for manufacturing the urethane sheet pad with different hardness of the bank portion have the following drawbacks, respectively.

That is, in the pad obtained by the method of FIG. 13, the entire bank portion f has a high hardness as shown in FIG. In addition, the joint surface between the high hardness foam and the low hardness foam is easily peeled off. Also, the pad obtained by the method of FIG.
Since the removal groove g of the partition plate remains on the top of the bank portion f as shown in FIG. 16 or the partition plate e made of foamed resin remains as shown in FIG. The g and the partition plate e are felt on the thighs and the like, which also causes a feeling of strangeness and makes it uncomfortable to sit on. Further, in the method shown in FIG. 14, during foaming, part of the liquids A and B move over the partition plates e, e and move to the opposite side, so that the boundary between the high hardness portion and the low hardness portion is unclear. And becomes unstable in terms of quality, and B
Since the liquid does not spread sufficiently to the back side of the pad (the part indicated by h in Fig. 16 and 17), it becomes insufficient in terms of supportability and skin material swelling, and the timing of injecting A and B liquids. However, if the timing is not correct, one of the liquids will pass over the partition plates e, e and flow in a large amount to the other side, so that a pad of appropriate quality cannot be obtained.

As another method for manufacturing the above-mentioned embankment part different hardness polyurethane sheet pad, a container made of expanded polystyrene is attached to both side walls in the mold, and liquid B is injected into this container and liquid A is injected into the other parts to foam. At the same time, a method has also been proposed in which the container A is contracted by external heating or the heat of foaming reaction to integrate the polyurethane foam of liquid A and the polyurethane foam of liquid B (JP-A-63-25008).

According to this manufacturing method, the above-mentioned problems such as sitting comfort, supportability, and skin material swelling property can be improved, but the following drawbacks remain.

(1) The foaming stock solution usually contains an organic solvent such as methylene chloride as a foaming agent. In such a case, the foaming polystyrene sheet constituting the container is dissolved by this solvent component immediately after the stock solution is injected, In some cases, the foaming undiluted solution flows out of the container and the purpose of separating the undiluted solutions A and B cannot be sufficiently achieved. Further, in this case, the container is extremely softened even if liquid leakage does not occur, it is difficult to hold the container in a predetermined shape until the end of foaming, and it may be impossible to stably form the seat pad. Occurs.

Further, when molding a molded product, the raw material is supplied into the mold through a nozzle, and the nozzle is washed with an organic solvent such as methylene chloride each time the raw material is supplied. At this time, the container may be damaged by the organic solvent used for cleaning.

(2) Further, in the above method, the expanded polystyrene container is heat-shrinked, but it is preferable that the container after heat-shrinking has flexibility equivalent to that of polyurethane foam. However, when a container is made of expanded polystyrene sheet prepared so that such good flexibility can be obtained after heat shrinkage, the container has low strength before heat shrinkage and poor self-supporting property. It is difficult to maintain a predetermined shape when the raw material is injected. On the other hand, when a container is made of a foamed polystyrene sheet prepared so that sufficient self-supporting property is obtained at the time of injecting the raw material, such a container becomes extremely hard and brittle after heat shrinkage, and is flexible. Not only the elasticity and elasticity required for the seat pad are impaired,
When it receives a large force or deformation, it may crack or break.

The present invention has been made in view of the above circumstances, in the case of manufacturing a bank portion different hardness polyurethane sheet pad,
By using a liquid storage container that always has the same flexibility and feel as polyurethane foam, the part of the embankment that touches the thighs can be formed softly, and the partitioning groove and the partition plate remain on the top of the embankment. Without letting
Good sitting comfort can be obtained, and the characteristics of the foaming raw material can be exhibited satisfactorily, and the hard part and the soft part can be well bonded and integrated, and the boundary between these different parts is clear and stable without a feeling of discomfort. It is an object of the present invention to provide a method for molding a polyurethane sheet pad that is formed in a uniform manner.

[Means and Actions for Solving the Problems] In order to achieve the above-mentioned object, the present invention uses a polyurethane sheet pad having a bank portion on both sides or a peripheral portion of a seat portion as a cavity and a center portion corresponding to the seat portion and the above. In a method of molding using a foaming mold having a side part corresponding to a bank part, a liquid reservoir made of foamed polypropylene or foamed polyethylene is mounted in each side part of the foaming mold, and a space between these liquid reservoirs is attached. Injecting the undiluted foaming liquid to obtain a low-hardness foam into the cavity, and injecting the undiluted foaming liquid to obtain the high-hardness foam into the liquid reservoir container to cause foaming, A method for molding a polyurethane sheet pad, characterized in that the polyurethane sheet pad remaining inside as is is obtained.

In the present invention, a polypropylene polypropylene or polyethylene foam liquid reservoir is provided in the side portion of the cavity,
Since the foaming stock solution for low hardness foam is injected into the cavities between the liquid reservoirs of each side part, and the foaming stock solution for high hardness foam is injected into the above liquid reservoir container, the bottom part of the side part The undiluted solution of low-hardness foam flows into the space. Therefore, the inside and top of the seat pad that touches the thigh is formed by the low-hardness foam as well as the seat. Never. Also, the liquid storage container remains in the bank of the pad,
Since it does not remain on the top, the seated person does not feel the remaining container. Further, the container prevents both undiluted liquids from being mixed with each other, and the high hardness portion and the low hardness portion of the pad are partitioned by the liquid storage container, so that the boundary between the high hardness portion and the low hardness portion is located at a predetermined position. Clearly formed and stable in quality. Further, by using foamed polypropylene or foamed polyethylene as the material of the liquid reservoir, it is possible to satisfactorily bond and integrate the hard part and the soft part without heat shrinking, and a container made of these materials is suitable. Since it has both excellent flexibility and rigidity, it can always give good elasticity to the seat pad without cracking or breaking even when subjected to a large force or deformation, and when it is embedded in the product There is no feeling of strangeness. Further, the container made of these materials is stable to an organic solvent such as methylene chloride, the compounding ingredients of the foaming stock solution are not limited, and a desired foaming raw material can be used. It can be fully reflected in the product.

Further, by appropriately setting the size, shape, plate thickness, mounting position, etc. of this liquid storage container, it is possible to variously change the shape, position, etc. of the boundary line between the high hardness portion and the low hardness portion,
Therefore, the performance of the pad such as support can be adjusted arbitrarily without modifying the mold at all.
By increasing the volume of the liquid storage container, a large amount of the foaming stock solution can be stored in the container, so that the accuracy of the injection timing and the injection amount of the foaming stock solution can be eased.

An embodiment of the present invention will be described below with reference to the drawings.

[Embodiment] First, as shown in FIGS. 1 and 2, the above-described foam molding die 4 having a center portion 2 corresponding to a seat portion of a seat pad and side portions 3 and 3 corresponding to a bank portion is provided in a cavity 1. Liquid reservoirs (5, 5) made of expanded polypropylene or expanded polyethylene are installed in the side parts (3, 3) in a state of being separated from the lowest surfaces of these side parts (3, 3). In addition, 6 and 6 show the weir board which protruded in the boundary of the center part 2 and the side parts 3,3. In this case, as the foaming mold, in addition to the one in which the side portions 3 and 3 are provided on both sides of the center portion 2 facing each other as shown in FIGS. It is also possible to use a molding die which has not only both sides but also the other side portions facing each other, and in this case, the liquid reservoir can be attached to the other both side portions. Further, as shown in FIG. 3, the closed mold 4 including the upper mold 4a and the lower mold 4b may be used, and the containers 5 and 5 may be attached to the upper mold 4a.

Here, the shape of the liquid reservoir 5 is not particularly limited, but it is preferable to use a container having an arched bottom. That is, as shown in FIG. 4, the seat pad 7 is formed by using the hollow hemispherical container 5 having an arch-shaped bottom, and when the seat pad 7 is formed by using the container 5 having a flat bottom as shown in FIG. Comparing with the case of molding, even if the width and volume of the boundary layer 8 are the same, the one of FIG. 4 has a stronger resistance to the external force F than the one of FIG. 5, and therefore the supportability becomes higher.

As this liquid storage container, it is preferable to use a container in which a liquid storage part 5a and a mounting part 5b are connected in series like the container shown in FIGS. Can be easily attached to, but Fig. 6 (A), (B)
As shown in Figure 5, a container or liquid reservoir consisting only of the liquid reservoir 5a
It is also possible to mount a container in which a small mounting piece 5c is connected to 5a in a mold of a molding die using a pin or the like. That is, as shown in FIGS. 7A and 7B, one side portion of the liquid reservoir 5 is attached to the attachment pins 3a, 3a, 3a arranged on the outer wall of the side portion 3 of the molding die 4. With the mounting piece
The container 5 is mounted in the mold of the molding die by attaching 5c to the pin 6a protruding on the barrier plate 6, or the support rod 3b is arranged in the central portion of the side portion 3 as shown in FIG. The container 5 can be mounted in the mold by mounting the liquid reservoir 5a on the pin 3c protruding from the tip of the support rod 3b. Further, in this case, when the attachment piece 5c is provided, the attachment piece 5c can be attached to the pin 6a of the dam plate 6 as in the case shown in FIG.

Further, as shown in FIG. 9, the container 5 having both the mounting portion 5b and the mounting piece 5c is used, and the mounting portion 5b is used.
The spigot part of the closed mold 4 (grinding part)
It is also possible to mount the container 5 in the side portion 3 by attaching it to the pin 3d provided on the 4c and attaching the attaching piece 5c to the pin 6a provided on the barrier plate 6. In this case, since the container 5 is made of expanded polypropylene or expanded polyethylene having excellent flexibility, the sealing property of the closed mold is not impaired even if the mounting part 5b is sandwiched between the spigot parts 4c of the mold.

At the time of mounting the container, the container 5 can be arranged apart from the outer wall of the side portion 3 so that the container 5 does not appear on the outer surface of the pad 7 as shown in FIG. However, in order to prevent lateral displacement of the container 5 and contact of the container 5 with the outer wall at this time, the support rod 9a and the support piece 9b are arranged in the side portion 3 as shown in FIG. 7 (B). Can be installed. Since the mounting pins 3a and 6a and the support rod 9a and the support piece 9b are needle-shaped or thin rod-shaped, they do not form a large hole or groove that impairs sitting comfort.

Further, as the container 5, as shown in FIG.
Width l is 20-100% of the total width of the side part, especially 40-80%,
The depth m is 10 to 100% of the total depth of the side part, especially 30 to 80
%, And a plate thickness of 1 to 6 mm, especially 1 to 4 mm is preferable, and thereby supportability can be improved. In addition,
Regarding the mounting position of the container 5, the distance n between the bottom of the side part 3 and the lower end of the container 5 is preferably 0 to 6 cm, particularly 1 to 6 cm, and more preferably 2 to 6 cm from the viewpoint of supportability.

Further, the volume of the container is preferably 0.8 to 2.5 liters, whereby the accuracy of the injection timing and the injection amount of the foaming stock solution can be relaxed and the productivity can be improved. Further, the inner and outer surfaces of the container may be processed to have an uneven surface to increase the surface area, thereby improving the adhesive strength with the urethane foam.

Next, a foaming stock solution for low-hardness foam (hereinafter referred to as "A liquid") is injected into the cavity between the liquid storage containers 5, 5, and a foaming stock solution for high-hardness foam (hereinafter referred to as B solution) is placed in the liquid storage containers 5, 5. It is called liquid and is injected to cause foaming.

In this case, the liquid A may be caused to flow from above the dam plate 6 to the center portion 2 and the side portion 3 as shown in FIG.
As shown in FIG. 12, the center portion 2 and the side portion 3 may be separately injected.

Further, as the foaming undiluted solution, soft, semi-rigid, those having a known composition as a foaming raw material of rigid polyurethane foam can be used, and those in which an organic solvent such as methylene chloride is blended as a foaming agent can also be preferably used, It is desirable to use liquid A which has a push-pull gauge (made by Aiko Engineering Co., Ltd.) of 10 to 20 kg / φ200 after foaming, and liquid B which has the same hardness of 1.8 to 4 kg / φ200 after foaming. This can enhance supportability.

In this way, the liquid reservoir container 5 made of expanded polypropylene or expanded polyethylene is arranged in the side parts 3, 3 of the foaming mold 4, and the liquid B is placed in the container 5 and the liquid A is placed in the cavity 1 other than the container 5. By injecting and foaming these,
The hard part and the soft part are well integrated, and the boundary between these different parts is formed clearly and stably, and the sitting comfort is good, and the characteristics of the foaming raw material are good. The hardness polyurethane sheet pad can be reliably manufactured.

That is, according to the above-described manufacturing method, the liquid A for low hardness foam flows into the bottom of the side portion 3 of the molding die 4, and the inner portion and the top portion which hit the thigh of the bank portion of the seat pad are as low as the seat portion. Since it is formed of a hardness foam, the thigh does not give a hard feel even when it hits the bank, and the container 5 remains in the bank of the pad and not at the top, so the seated person can feel the remaining container. In addition, it is possible to prevent the A liquid and the B liquid of the foaming raw material from being mixed with each other by the container 5, and the high hardness portion and the low hardness portion of the pad are surely partitioned by the container 5 so that the boundary between the both hardness portions is high. Is clearly formed at a predetermined position, and the quality is stable. Moreover, since the container 5 is formed of expanded polypropylene or expanded polyethylene, the high hardness portion and the low hardness portion are well bonded and integrated without heat shrinking the container 5, and the container 5 has an appropriate rigidity. Since it also has flexibility, good elasticity can always be given to the bank portion of the seat pad without cracking or breaking even when subjected to a large force or deformation. Further, this container 5 is stable to an organic solvent, and the components to be mixed in the foaming stock solution are not limited. A desired foaming raw material is used, and the characteristics of the foaming raw material (liquid A, liquid B) are sufficient for the product. It can be reflected. Further, when the container 5 is made of expanded polyethylene, in addition to the above effects, it is more advantageous in terms of cost than the conventional manufacturing method using a expanded polystyrene container.

The method for molding the polyurethane sheet pad of the present invention is not limited to the above-mentioned embodiment. For example, in the above-mentioned embodiment, one liquid reservoir container is provided at each side portion, but if necessary, each side container is provided. It is also possible to provide two or more liquid reservoirs in each part, and to inject the same foaming raw liquid into these plural liquid reservoirs, or to inject the foaming raw liquids having different characteristics from each other. The shape and the like of the molding die may be variously modified within the scope of the present invention.

[Effects of the Invention] As described above, the present invention has the following effects.

It is possible to obtain a seat pad that has a soft inner portion and a top portion that touch the thighs of the bank portion and that is comfortable to sit on.

It is possible to obtain a seat pad that does not give an uncomfortable feeling to a seated person without making the seated person feel the remaining liquid storage container.

Since it is possible to prevent the high-hardness foam undiluted solution and the low-hardness foam undiluted solution from being mixed with each other, the boundary between the high-hardness portion and the low-hardness portion can be clearly formed and stably formed at a predetermined position, Therefore, a seat pad with stable quality can be obtained.

It is possible to obtain a seat pad in which the high hardness portion and the low hardness portion are well bonded and integrated.

By appropriately setting the shape, size, plate thickness, and mounting position of the liquid storage container, the performance of the seat pad such as supportability can be arbitrarily adjusted.

By increasing the volume of the liquid storage container, the accuracy of the injection timing and the injection amount of the foaming stock solution can be relaxed, and therefore the productivity can be improved.

The above adjustment can be easily performed by changing the shape of the container without modifying the mold.

By making the pad side end portion hard, the contour of the pad can be clarified and the appearance of the seat skin can be improved.

There is no limitation on the blending component of the foaming raw material, a desired raw material can be used, and the characteristics of the foaming raw material injected into the liquid storage container can be well reflected in the product.

It is possible to surely obtain stable elasticity and good sitting comfort without causing the liquid reservoir container to be easily cracked or broken.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a molding die used for carrying out the present invention, FIG. 2 is a plan view of the molding die, FIG. 3 is a sectional view showing another example of the molding die, FIG. 4 and FIG. FIG. 5 is a partially omitted sectional view showing a seat pad obtained by the present invention, respectively.
Figures (A) and (B) are perspective views showing other examples of the container, and Figures 7 (A), (B) to 9 show the mounting mode of the liquid reservoir, respectively. ) Is a partial plan view, 7th
7B is a sectional view taken along line BB in FIG. 7A, FIGS. 8 and 9 are sectional views showing other mounting modes, and FIG. 10 is another example of a pad. Sectional views showing, FIG. 11 and FIG. 12 are explanatory views showing a state of injecting a foaming stock solution in the present invention, FIG. 13 and FIG. 14 are explanatory views showing a conventional molding method, respectively, and FIGS. FIG. 3 is a partially omitted sectional view showing a seat pad obtained by a conventional method. 1 ... Cavity, 2 ... Center part, 3 ... Side part, 4 ... Foaming mold, 5 ... Liquid reservoir.

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Claims (1)

[Claims] 1. A polyurethane sheet pad having a bank on both sides or a peripheral edge of a stool is molded in a cavity using a foaming mold having a center part corresponding to the stool and a side part corresponding to the bank. In the method described above, a liquid storage container made of expanded polypropylene or expanded polyethylene is attached in each side part of the foaming mold, and a foaming stock solution for obtaining a low-hardness foam is injected into a cavity between the liquid storage containers. At the same time, a polyurethane sheet pad in which the liquid storage container remains as it is inside is obtained by injecting a raw foaming liquid for obtaining a high-hardness foam into the liquid storage container to perform foaming. Sheet pad molding method.