JP2000125995A - Production of pad for seat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease molding defects, such as air pockets and under fills, and to improve moldability by blowing a polyurethane stock solution added with carbon dioxide to the prescribed sections in a forming mold and executing expansion molding. SOLUTION: The forming mold 10 is two-split metal molds consisting of a recessed lower mold 12 which is approximately horizontally held and molds the front surface side of a pad and an upper mold 14 which is capable of opening and closing the lower mold 12 by turning around a hinge part 13 disposed at one end of this lower mold 12 and molds the rear surface side of the pad. At least one side wall of the lower mold 12 is provided with an undercut part 12a bulging toward an outer side. The upper mold 14 is provided with a projecting part 14 which projects upward. The polyurethane stock solution 16 prefoamed by adding the carbon dioxide thereto is directly blown to the undercut part 12a of the lower mold 12, the corner part of the forming mold 10 for molding the corner part of the pad 30 and the projecting part 14a of the upper mold 14 in the state of opening the upper mold 14. The upper mold 14 is then closed and expansion molding is executed within the forming mold 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a pad for a seat, which is a cushion used mainly for an automobile seat.

[0002]

2. Description of the Related Art Seat pads called cushion pads and bag pads used for seats and backrests of automobile seats are obtained by injecting a polyurethane solution into a molding die.
It is manufactured by foam molding.

[0003] In detail, a polyurethane stock solution comprises a polyol and an isocyanate, and is usually injected into a mold while continuously mixing them according to a predetermined composition. The injected polyurethane stock solution undergoes foaming and certain curing in a molding die to foam-mold a sheet pad made of urethane foam.

Conventionally, in such foam molding, FIG.
As shown in (a), a concave lower mold 1 held substantially horizontally
2 and an upper mold 14 for opening and closing the lower mold 12, a polyurethane undiluted solution 22 is injected from the nozzle 20 into the lower mold 12 with the upper mold 14 opened, and FIG.
As shown in (b), it is common to foam the pad 30 by closing the upper mold 14.

[0005]

However, in such a conventional method, the undercut portion 12a of the lower mold 12 and the upper mold 14 and the upwardly projecting convex portion 14a of the upper mold 14 have the liquid of the polyurethane stock solution 22. The rotation is poor, and as a result, as shown in FIG. 7A, an air pool X is generated in a portion corresponding to the undercut portion 12a,
As shown in FIG. 7B, there is a problem that molding failure is likely to occur, for example, the underfill Y is generated in a portion corresponding to the convex portion 14a of the upper die 14.

Accordingly, an object of the present invention is to provide a method of manufacturing a sheet pad which is excellent in moldability by reducing molding defects such as air pockets and underfill.

[0007]

The method for producing a sheet pad according to the present invention is a method for producing a sheet pad by injecting an undiluted polyurethane solution into a molding die and subjecting it to foam molding. Is sprayed onto a predetermined portion of a molding die and foamed.

[0008] The polyurethane stock solution is usually a highly fluid liquid immediately after mixing the polyol and the isocyanate for about 5 seconds, but when carbon dioxide gas is added, immediately after the addition, the final foaming state is reduced. About 20 to 25% is in a pre-foamed state, which is a foamed state, and in this state, the fluidity is significantly reduced. Therefore, when a polyurethane solution to which carbon dioxide is added is sprayed on a predetermined portion of the mold,
Due to its low fluidity, the polyurethane concentrate is less likely to flow from the sprayed site to other sites. Therefore, it is possible to preferentially foam from the sprayed portion, and it is possible to prevent molding defects such as air pockets and underfill in the portion.

Therefore, the above-mentioned predetermined portion is a molding die having a concave lower die held substantially horizontally and an upper die for opening and closing the lower die. It is preferable to set a part that is difficult to mold, such as a convex part protruding upward, where molding defects are likely to occur.

Further, in order to manufacture a substantially bag-shaped sheet pad in which an inward flange portion is integrally provided on a side portion on the back surface side of the pad, a concave lower mold for molding the front surface side of the pad is provided. A three-part mold comprising an upper mold that can be opened and closed with respect to the lower mold, and a core that is set in the upper mold and that is provided separately from the upper mold so as to be separable and that forms the inside of the flange portion. When using the molding die described above, it is preferable that the predetermined portion is set to a portion of the molding die where the flange portion is molded.

In the above description, the term "stock solution of polyurethane to which carbon dioxide is added" refers to a stock solution of polyurethane to which carbon dioxide is added separately from carbon dioxide produced by the reaction between isocyanate and water.

The carbon dioxide gas may be added to the mixture immediately after the mixing of the polyol and the isocyanate, or may be added to the polyol or the isocyanate immediately before the mixing of the polyol and the isocyanate.

The amount of carbon dioxide added is
It is preferably 4.0 parts by weight or less based on 00 parts by weight. If the amount exceeds 4.0 parts by weight, the open cell effect due to the addition of carbon dioxide gas becomes excessive, which may cause a problem of causing collapse. Usually, it may be about 2.0 parts by weight based on 100 parts by weight of the polyol.

Further, in the above, the entire pad may be formed only with the carbon dioxide-added polyurethane stock solution sprayed on a predetermined portion, or in addition to the spraying on the predetermined portion, a separate molding may be performed. A polyurethane solution may be injected into a mold and foamed.

The polyol used in the present invention is not particularly limited, but a polyfunctional polyol having a functional group number of 3 or more is used because the stability of the foam is maintained against the open cell effect due to the addition of carbon dioxide. Is preferred. Although the isocyanate is not particularly limited, it is usually T
DI, MDI, etc. are used.

[0016]

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

FIG. 1 is a sectional view of a molding die 10 in a method for manufacturing a sheet pad according to a first embodiment of the present invention.

This embodiment relates to a method of manufacturing the pad 30 shown in FIG. The pad 30 is a substantially rectangular cushion pad used for a seat surface of an automobile seat.

As shown in FIG. 1, a molding die 10 is held substantially horizontally and has a concave lower die 12 for molding the front side (upper side) of the pad 30, and is disposed at one end of the lower die 12. An upper die 14 for molding the back surface (lower surface side) of the pad 30 that can open and close the lower die 12 by rotating about the hinge portion 13.
This is a split mold consisting of

At least one side wall of the lower mold 12 is provided with an undercut portion 12a bulging outward. The upper mold 14 is provided with a convex portion 14a protruding upward.

When manufacturing the cushion pad 30 using the molding die 10, as shown in FIG. 1, the upper die 14 is opened and the undercut portion 12 of the lower die 12 is opened.
a, a foam stock 16 pre-foamed by adding carbon dioxide to the corners of the mold 10 for shaping the corners A of the pad 30 shown in FIG.
Is blown directly from the nozzle 18, the upper mold 14 is closed, and foam molding is performed in the molding die 10 as shown in FIG.

Here, in the present embodiment, the amount of spraying on each part is made in order to form the entire cushion pad 30 only with the above-described undercut portion 12a, the undiluted polyurethane solution 16 sprayed on the corners and the convex portions 14a. Has been adjusted.

According to this embodiment, the polyurethane stock solution 16 to which carbon dioxide gas has been added has a low fluidity due to prefoaming immediately after the addition, so that it is difficult for the solution to flow from the sprayed portion to another portion. . Particularly, in the convex portion 14a of the upper mold 14, when the carbon dioxide gas is not added, the polyurethane stock solution almost flows down to the lower mold 12 due to the mold closing operation. The polyurethane undiluted solution 1 is applied to the convex portion 14a.
6 can be stopped.

For this reason, the foam can be preferentially foamed from the sprayed portion, and the foam spreads throughout the molding die 10 based on the portion, so that the undercut portions 12a and the corners which are difficult to mold are formed. Molding defects in the convex part 14a of the upper part and the upper mold 14 can be prevented. In addition, by such a simple method of adding and spraying carbon dioxide gas, it is possible to prevent molding defects,
The cushion pad 30 having good moldability can be manufactured at low cost.

FIG. 2 is a sectional view of a molding die in a method for manufacturing a sheet pad according to a second embodiment of the present invention.

In the second embodiment, in addition to the spraying of the stock solution 16 of carbon dioxide added to the difficult-to-mold portion in the first embodiment, the stock solution of polyurethane 22 is separately injected into the lower mold 12. And foam molding.

That is, as shown in FIG. 2A, with the upper die 14 opened, the undercut portion 12 of the lower die 12 is opened.
a and an undiluted polyurethane solution 16 in which carbon dioxide is added to the convex portion 14a of the upper mold 14 by a nozzle 18, and thereafter,
As shown in FIG. 2B, the nozzle 2
The polyurethane stock solution 22 is poured from 0, the upper mold 14 is closed, and foam molding is performed as shown in FIG.

In this case, the undiluted polyurethane solution 16 sprayed on the undercut portion 12a and the convex portion 14a and the lower mold 12
The undiluted polyurethane solution 22 injected into the mold 10 is integrated in the mold 10 to form the cushion pad 30. Therefore, the amounts of the undiluted polyurethane solution 16 and the undiluted polyurethane solution 22 are adjusted so that the entire cushion pad 30 is foam-molded.

Here, the polyurethane stock solution 22 to be injected into the center of the lower mold 12 may be the same formulation as the above-mentioned sprayed polyurethane stock solution 16 or may be a different formulation. Also, with or without the addition of carbon dioxide gas, Is also good.

Note that when carbon dioxide gas is added to the undiluted polyurethane solution, the hardness of the foamed molded article becomes lower than when no carbon dioxide gas is added. Therefore, the above-mentioned sprayed polyurethane stock solution 1
In the case where 6 and the undiluted polyurethane solution 22 have the same composition, when the latter 22 is injected without adding carbon dioxide gas, a hardness difference occurs in the pad 30. Therefore, when it is desired to make the pad 30 have a hardness difference, the above-mentioned polyurethane stock solution 16 to be sprayed and the polyurethane stock solution 22 to be injected are used.
And the same composition, and it is preferable to add carbon dioxide only to the polyurethane stock solution 16 to be sprayed. On the other hand, when carbon dioxide gas is also added to the polyurethane stock solution 22 to be injected, the hardness of the pad 30 can be made uniform. In addition, when carbon dioxide is not added to the polyurethane solution 22 to be injected into the lower mold 12, in order to make the hardness of the pad 30 uniform, the composition of the polyurethane solution 16 to be sprayed and the polyurethane solution 22 to be injected should be different. In this case, the latter 22 may be used in such a manner that a molded product having a lower hardness can be obtained.

Further, when carbon dioxide gas is added to the undiluted polyurethane solution, (1) the surface layer of the molded article is softened and the tactile sensation is improved. (2) If the density is the same, the amount of water added during blending should be reduced. Therefore, an effect that excessive urea bonds are hardly generated and deterioration of wet heat compression set can be prevented, so that a problem of deterioration in settability of a molded body can be avoided. Therefore, if such effects are emphasized, it is preferable to add carbon dioxide gas to both the above-mentioned polyurethane stock solution 16 to be sprayed and the polyurethane stock solution 22 to be injected.

FIGS. 3 to 5 relate to a third embodiment of the present invention.

In the third embodiment, a back pad 40 shown in FIG. 3 is used for a backrest of an automobile seat.
A method for producing the same. The back pad 40 has flange portions 42 inwardly formed on three sides of both sides and an upper side for mounting the seat frame on the back side of the substantially rectangular pad.
Have a substantially bag shape integrally provided.

A molding die 50 for molding the pad 40 includes:
As shown in FIG. 4, the lower mold 52 is held substantially horizontally and forms a surface of the pad 40, and the lower mold 52 is pivoted about a hinge 53 provided at one end of the lower mold 52. An upper die 54 capable of opening and closing the die 52, and a core 56 which is set in the upper die 54 and is provided separately from the upper die 54 so as to be separable and forms the inside of the flange portion 42. This is a split mold.

When molding the pad 40 using the molding die 50, the upper die 54 and the core 56 are opened with respect to the lower die 52 as shown in FIG.
Is separated from the upper mold 54, and a carbon stock is added to a portion 54 a of the upper mold 54 where the flange portion 42 is formed, and a pre-foamed low-fluid polyurethane stock solution 16 is added.
Is sprayed directly by the nozzle 18. Further, the polyurethane undiluted solution 22 is injected into the center of the lower mold 52 from the nozzle 20. Here, the polyurethane solution 22 to be injected into the lower mold 52
In the same manner as in the second embodiment described above, the mixture may be the same as or different from the undiluted polyurethane solution 16 sprayed by the nozzle 18, and carbon dioxide may be added or not added. Thereafter, as shown in FIG.
Is closed and foam molding is performed in the molding die 50.

In the above, the upper mold 54 and the core 5
6 where the flange portion 42 is formed in a state in which the flange 6 is opened.
Although the undiluted polyurethane solution 16 is sprayed on the portion a, the undiluted polyurethane solution 16 may be sprayed toward the recess formed by closing the upper mold 54 and the core 56.

Also in this embodiment, the flange 42
Since the undiluted polyurethane solution 16 sprayed on the portion 54a where the resin is molded has a low fluidity due to the addition of carbon dioxide, it is difficult to flow to other portions, and therefore, it can be preferentially foamed from the portion. Therefore, molding failure in the flange portion 42 can be prevented.

[0038]

As described above, according to the present invention,
By spraying a pre-foamed low-fluid polyurethane stock solution with the addition of carbon dioxide gas on the difficult-to-mold area, the sprayed polyurethane stock solution is separated from the sprayed area due to its low flow property. It is difficult to flow to the part of
Therefore, it is possible to preferentially foam from the sprayed portion, and it is possible to prevent molding defects such as air pockets and underfill in the portion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a molding die in a manufacturing process of a sheet pad according to a first embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views of a forming die in a manufacturing process of a sheet pad according to a second embodiment.

FIG. 3 is a perspective view of a sheet pad according to a third embodiment.

FIG. 4 is a cross-sectional view of a molding die during foam molding in a method for manufacturing a sheet pad according to a third embodiment.

FIG. 5 is a cross-sectional view of a molding die at the time of spraying an undiluted polyurethane solution in the same manufacturing method.

6A and 6B are cross-sectional views of a molding die in a conventional manufacturing process of a sheet pad, wherein FIG. 6A shows a time when a polyurethane undiluted solution is injected, and FIG.

FIG. 7A is a perspective view showing a front side of a sheet pad manufactured by a conventional manufacturing method, and FIG. 7B is a perspective view showing a back side of the sheet pad.

[Explanation of symbols]

 Reference Signs List 10 Molding die 12 Lower die 12a Undercut portion 14 Upper die 14a Convex part of upper die 16 Undiluted polyurethane solution to which carbon dioxide is added 18 Nozzle 30, 40 Sheet Pad 42 Flange 50 Mold 52 Lower mold 54 Upper mold 54a Flange molding part 56 Core

Claims (3)

[Claims] 1. A method of manufacturing a sheet pad by injecting a polyurethane stock solution into a mold and foaming the same, wherein a polyurethane stock solution to which carbon dioxide gas has been added is sprayed onto a predetermined portion of the mold to foam and mold. A method for producing a pad for a sheet, comprising: 2. The mold according to claim 1, wherein the mold includes a concave lower mold held substantially horizontally, and an upper mold for opening and closing the lower mold. 2. The method according to claim 1, wherein the pad is at least one of a corner portion and a convex portion protruding upward in the upper mold. 3. A method for manufacturing a substantially bag-shaped sheet pad, wherein an inward flange portion is integrally provided on a side portion on a back surface side of the pad, wherein the molding die forms the front surface side of the pad. A concave lower mold to be opened, an upper mold that can be opened and closed with respect to the lower mold, and a core that is set in the upper mold and that is provided so as to be able to be separated from the upper mold and forms the inside of the flange portion. The method according to claim 1, wherein the predetermined portion is a portion where the flange portion is formed.