JPS628783A - Production of seat cushion pad having different hardness layers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a seat cushion pad having plastic foam layers of different hardness, including a relatively hard layer and a soft layer. The present invention relates to a method of manufacturing a seat cushion pad in which layers are simultaneously foam-molded.

(Prior Art) In cushion pads used for automobile seats, the upper layer that comes into contact with the occupant is formed of a flexible plastic foam such as polyurethane foam, so as to provide a good feeling when sitting on the seat and It is desirable that the lower layer be formed of a relatively rigid plastic foam to ensure its support. In such a case, conventionally, for example, the upper layer is pre-molded from a soft plastic foam, and this is placed in a mold that molds the cushion pad with it upside down.
By foaming and molding relatively hard plastic foam thereon, a seat cushion pad having layers of different hardness was obtained.

However, this manufacturing method not only requires a separate mold for the upper layer, but also impregnates the surface of the pre-molded soft plastic foam layer with the foaming solution for the hard plastic foam layer, resulting in a poor quality of the product. An extremely hard boundary layer is formed between the soft layer and the hard layer, resulting in a problem in that the feeling when sitting is deteriorated and the durability is also poor.

In view of these problems, a method has been proposed in which a layer made of soft plastic foam and a layer made of relatively hard plastic foam are simultaneously foam-molded, as shown in Japanese Patent Application Laid-Open No. 55-98195. There is. In this method, first, a first foaming solution that foams to form a hard plastic foam layer is poured into a mold, and after this first foaming solution foams to some extent, a second foaming solution that becomes a soft plastic foam layer. The second foaming stock solution is injected and the first and second foaming stock solutions are foamed and hardened.

By using such a method, the second foaming stock solution is injected when the first foaming stock solution partially foams and expands inside the mold and its specific gravity becomes small.
The foaming stock solution sinks below the first foaming stock solution to form a layer due to the difference in specific gravity. Therefore, if these first and second foaming stock solutions are foamed and hardened in that state,
It is possible to obtain a single-layer plastic foam molded product of different hardness, in which the lower layer is a soft plastic foam layer and the upper layer is a hard plastic foam layer. When used as a seat cushion pad, the obtained product may be turned upside down.

However, in this method of floating the first foaming stock solution to the upper surface of the foaming stock solution 82 using the difference in specific gravity between the first foaming stock solution and the second foaming stock solution, the first foaming stock solution is The second foaming stock solution must be injected after foaming and expanding until its specific gravity becomes reliably lower than that of the second foaming stock solution. The foaming stock solution is injected when the first foaming stock solution foams and expands to 10% or more of its potential expansion amount.

The time when the foam reaches about 10% of the potential expansion amount is the time when the first foaming solution has been foamed and hardened to a considerable extent. Therefore, if the second foaming stock solution is injected at such a time, there will be a difference in fluidity between the second foaming stock solution and the first foaming stock solution, making it difficult to obtain a uniform calendar throughout. .

In view of these problems, the present inventor proposed a method in which the second foaming stock solution is injected while the first foaming stock solution remains in a substantially liquid state, and the second foaming stock solution is infiltrated below the first foaming stock solution. (Patent Application No. 59-211!8281 and Patent Application No. 1973)
No. 9-287389).

(Problems to be Solved by the Invention) By the way, when molding a seat cushion pad having a plastic foam layer of different hardness by such a method, the mold used for the molding is such that the cushion pad is molded with the cushion pad upside down. It is assumed that Therefore, the upper surface of the cushion pad is formed by the upper surface of the lower mold. Usually, the upper surface of the cushion pad is relatively flat. However, the support parts on both sides are often formed higher than the central seat part, and the seat part is inclined slightly upward toward the front.
In many cases, an upwardly protruding part is formed on the rear end edge to support the buttocks of the occupant. In such cases, the upper surface of the lower mold has an inclined surface that slopes downward from front to back or from side to side with the ridge line as the boundary. Be prepared.

Since the seat surface is formed sufficiently wide, one side of the sloped surface is long and slopes gently, and the other side is short and slopes at a large angle.

On the other hand, the foaming stock solution poured into such a mold has high fluidity until it foams to a certain extent.

For this reason, if the foaming solution is injected, for example, near the ridgeline of the upper surface of the lower mold, more of the foaming solution will flow toward the short and steeply sloped surface. The thickness of the layer cannot be controlled to a predetermined thickness, and the interface between the soft layer and the hard layer of the molded cushion pad is distorted. If the soft plastic foam layer is thicker than a predetermined thickness, the buttocks will sink considerably when seated, making it impossible to obtain a good fit.

Furthermore, if the foaming stock solution in a liquid state flows forcefully toward a short, steeply sloped surface, turbulence will occur there. Therefore, if it is the second foaming stock solution that forms the lower layer of the first foaming stock solution, the interface therebetween will be disturbed and the foaming stock solutions will mix together.

The present invention has been made in view of such problems, and its purpose is to use a mold with a short sloped surface and a long sloped surface formed on the upper surface, and to form a soft layer with a predetermined thickness. It is an object of the present invention to provide a seat cushion pad having a particularly hard layer.

(Means for solving the problem) In order to achieve this object, in the present invention, after the first foaming stock solution is injected, the second foaming stock solution is injected into the mold along the ridge line of the upper surface of the mold. The mold is injected onto the upper surface of the mold at a certain distance away from the long inclined surface.

(Function) By doing this, the second foaming stock solution overflows over the ridgeline and forms a short slope.

It will flow to the side. Therefore, a large amount of the foaming stock solution does not flow to the short slope side, and the flow becomes gentle. Further, on the long slope side, the foaming stock solution flows in a laminar flow. Therefore, the interface between the first foaming stock solution and the second foaming stock solution will not be disturbed.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

In the drawings, FIG. 1 shows an embodiment of the method for manufacturing a seat cushion pad according to the present invention, and is a longitudinal sectional view showing the state of the foaming solution inside the mold at each stage of the manufacturing process. Further, FIG. 2 is a perspective view of a mold used in the manufacturing method, and FIG. 3 is a partially cutaway perspective view of a cushion pad for an automobile seat obtained by the manufacturing method.

As is clear from FIG. 3, the automobile seat cushion pad 1 includes a seat portion 2 that supports the weight of an occupant, and both side support portions 3.3 on both the left and right sides of the seat portion 2.
is formed higher than the central seat surface 2, so that one occupant can be supported without moving in the left-right direction even when a lateral load is applied during cornering of the vehicle. The seat portion 2 is inclined slightly upward toward the front, and is formed so that the thighs of the occupant are supported in a stable driving posture. Further, an upwardly protruding portion 2 is provided at the rear end edge of the seat portion 2 to fit the rear surface of the occupant's buttocks and prevent rearward movement.
a is formed.

The upper part of the seat part 2 is formed of a soft polyurethane foam layer 4 so that the occupant can be supported softly. In addition, the lower part of the seat part 2 and both side support parts 3
is formed by a relatively hard polyurethane foam layer 5 in order to provide reliable support.

Such a cushion pad 1 is molded using an aluminum alloy mold 6 as shown in Figure MS2. In this mold 6, a lower mold 7 molds the upper surface side of the cushion pad 1, and an upper mold 8 molds the lower surface thereof. Therefore, the cushion pad l is molded by this mold 6 in an upside-down state.

As is clear from FIG. 1.2, the upper surface of the lower mold 7 is provided with a central molding part 9 for molding the seat part 2 of the cushion pad 1 and both side molding parts 10 for molding the support parts 3 on both sides. ing. The central molded portion 9 is formed with a long inclined surface 9a that gently slopes downward toward the front (to the right in the figure). Further, a short inclined surface 9b that slopes downward at a relatively large angle toward the rear is formed at the rear end edge. Therefore, the central molded portion 9 has the highest ridgeline 9c between the long sloped surface 9a and the short sloped surface 9b. A protruding weir 11 is provided between the central molded part 9 and both side molded parts 10.

When molding the first cushion pad using such a mold 6, first, as shown in FIG. 1(A),
The upper mold 8 is opened, and a predetermined amount of the first foaming stock solution 13 is discharged and injected from the first nozzle 12 onto the central molding part 9 of the lower mold 7 . This first foaming stock solution 13 is foamed to form a relatively hard polyurethane foam layer 5. The first foaming stock solution 13 is injected at the ridge line 9 of the central molding section 9.
It is assumed that it is on a long inclined surface 9a that is a predetermined short distance r away from c.

Subsequently, as shown in FIG. 1(B), a predetermined amount of the second foaming stock solution 15 is discharged and injected from the second nozzle 14. This second foaming stock solution 15 foams to form the soft polyurethane foam layer 4. The injection position of the second foaming stock solution 15 is similarly placed on the long inclined surface 9a that is a predetermined short distance r away from the ridgeline 9c of the central molding section 9. The second foaming stock solution 15 infiltrates below the first foaming stock solution 13 due to its discharge pressure, and forms a layer below the first foaming stock solution 13. As a result, a part of the first foaming stock solution 13 overflows over the weir 11 and flows to both side molding parts IO.

On the other hand, the first and second foaming stock solutions 13.
As shown in FIG. 1(C), part of the water 15 flows over the ridgeline 9c to the short slope 9b, and the rest flows along the long slope 9a and spreads out. During this time, type 6
are heated, and the first and second foaming stock solutions 13.15
is starting to foam. Therefore, these first and second
The foaming stock solution 13.15 flows while foaming, and the portion where fluidity has decreased due to foaming to some extent remains in the original position, and only the portion with high fluidity in a liquid state flows further downward.

In this way, as shown in FIG. 1(D), when the first and second foaming stock solutions 13.15 are spread throughout the mold 6, the thicknesses of those layers have a predetermined thickness distribution. Become. If foaming is continued in this state, the first and second foaming stock solutions 13.15 will be completely foamed and will fill the entire inside of the mold 6, as shown in FIG. 1(E).

When the first and second foaming stock solutions 13 and 15 are completely foamed and cured in this way, they become a relatively hard polyurethane foam layer 5 and a soft polyurethane foam layer 4, respectively, and these layers 5 and 4 become A continuously integrated laminate molded product is obtained. The boundary surface between the layers 4 and 5 is approximately planar.

When this molded product is removed from the mold 6 and turned upside down, only the upper surface of the seat portion 2 is covered with a soft polyurethane foam layer 4, and the surrounding area is a relatively hard polyurethane foam layer. 5 and in which the front and rear portions of the seat portion 2 are inclined upwardly can be obtained.

In this way, by injecting the second foaming stock solution 15 from the ridgeline 9c of the mold 6 to a position a certain distance #r away from the long slope 9a side, the short slope 9b side has the following properties:
Only the amount that overflowed over the ridgeline 9c will flow into the river.

Therefore, if the injection position is determined in advance according to the inclination angle of the long slope 9a and the injection amount of the second foaming stock solution 15, the second foaming stock solution 1 is guided to the short slope surface 9b side.
It becomes possible to control the amount of 5 to the optimum amount. In addition, since the foaming stock solution 15 flows over the ridgeline 9c to the short inclined surface 9b, the flow becomes gentle and no turbulence occurs. Therefore, the interface with the first foaming concentrate 13 will not be disturbed.

Since the long slope 9a side is sufficiently wide, turbulence does not occur in the flow of the foaming stock solution 13.15.

The present inventor discovered that the ridgeline 9 at the injection position of the second foaming stock solution 15
An experiment was conducted to find the optimal distance r from c. In the experiment, the total length of the central molded part 9 was 51Qmm, and the long inclined surface 9
A mold 6 with a length of 400 m1M and a mirror-finished inner surface was used. The first foaming stock solution 13 is injected for 2.5 seconds at a rate of 269g per second, and the second foaming stock solution 15 is injected at a rate of 269g/second.
The zero foaming conditions, in which injection was performed at a speed of 80g for 1.3 seconds, were the same as in the normal case.

As a result of the experiment, when the inclination angle of the long inclined surface 9a with respect to the horizontal plane is 5° to IO°, especially 5° to 7°,
It has been found that a desirable cushion pad 1 can be obtained by injecting the foaming stock solution 15 at a position offset by about 25 mm from the ridgeline 9c toward the long slope 9a.

In the above embodiment, the first foaming stock solution 13 is also injected at the same position as the second foaming stock solution 15, but the first foaming stock solution 13, which is injected first, may be slightly injected at the time of injection. Even if turbulent flow occurs, it will not cause any problem, so the injection position may be closer to the ridgeline 9c. In that case, a large amount of the first foaming stock solution 13 will flow into the short slope 9b side, but the height of the weir 11 should be set appropriately so that it overflows from the short slope 9b side to the molding parts 10 on both sides. The amount can be adjusted by means such as.

Further, in the above embodiment, a case where a long inclined surface 9a and a short inclined surface 9b are formed in the central molding part 9, which is a part of the upper surface of the mold 6, on both sides of the ridgeline 9c is taken as an example. However, the present invention can also be applied to a case where a long sloped surface and a short sloped surface are provided on either side of a ridgeline extending in the front-rear direction.

(Effect of the invention) As is clear from the above explanation, according to the present invention, the first
The second foaming stock solution injected after the foaming stock solution is injected at a position a certain distance away from the ridge line between the long slope and the short slope on the upper surface of the mold toward the long slope. As a result, a predetermined amount of the second foaming stock solution is distributed to each inclined surface side, and a seat cushion pad having a soft plastic foam layer of a predetermined thickness can be obtained. In addition, the flow of the foaming stock solution becomes gentle and the interface between it and the first foaming stock solution is not disturbed, so that the flow between the soft plastic foam layer and the hard plastic foam layer becomes It becomes possible to obtain a seat cushion pad with a flat interface. Therefore, the seat cushion pad provides good seating comfort.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the method for manufacturing a seat cushion pad according to the present invention, and (A) to (E) show the states of the mold and the foaming solution inside the mold at different stages of the manufacturing process. FIG. 2 is a perspective view of the mold used for manufacturing the seat cushion pad, and FIG. 3 is a partially cutaway view of the automobile seat cushion paratra obtained by the manufacturing method. FIG. 1...Seat cushion pad 2...Seat surface part 4...Soft polyurethane foam layer 5...Hard polyurethane foam layer 6...Mold 7...Lower mold 9...Central molding part (of the mold) Upper surface) 9a...Long slope 9b...Short slope 9
c...Ridge line 12...First nozzle 13.
...First foaming stock solution 14...Second nozzle 15...
・Second foaming stock solution

Claims (1)

[Claims] On the upper surface 9 of the mold 6, which has a long inclined surface 9a and a short inclined surface 9b that slope downward on both sides with a ridgeline 9c in between, a first molding material which is foamed to form a relatively hard plastic foam is provided. A second foam that foams with the foaming stock solution 13 to form a soft plastic foam.
This is a method for producing a seat cushion pad having plastic foam layers of different hardness by sequentially injecting the foaming stock solutions 15 and forming a layer of the foaming stock solutions 13 and 15 in the mold 6 and foaming and hardening them. A seat cushion having a layer of different hardness, characterized in that the second foaming stock solution 15 is injected from the ridge 9c of the mold 6 to a position a certain distance r away from the long slope 9a side. Method of manufacturing pads.