JPH03151214A - Mold for molding of hot cure urethane foam - Google Patents

Abstract

PURPOSE:To obtain a urethane molded product to which a film is stuck, by a method wherein the film is suck to a molding surface through a small hole in the molding surface by generating negative pressure in a chamber in a die and a stock solution of urethane resin is cast onto the film and foam molding is performed. CONSTITUTION:A film 14 is set up on a molding surface 13 of a die 10, negative pressure is applied to the molding surface 13 through a small hole 15 by decompressing the inside of a chamber 11 and a film 14 is molded into a fixed form by sucking the film 14 to the molding surface 13. Then an intermediate die 21 is set up on a die 10, a top force 22 is put over the same and the chamber 11 is decompressed away in succession. Then a stock solution 24 of a hot cure urethane foam is cast within a cavity 23 through a nozzle 25 and a urethane foam pad 2 is obtained by reacting and curing the stock solution. With this construction, monolithic molding of the skin of the hot cure urethane becomes possible without generating a hindrance of adhesion with a mold release material.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a mold for molding body cure urethane used for vehicle seats and pads for furniture cushions such as chairs. [Prior art] Sheets made by the Surebond method (5URE-BOND method), in which a skin is integrally attached to the surface of a pad made of urethane foam, are not highly durable and cannot be used repeatedly due to their design advantages. It also tends to be used a lot, especially in car seats, because it does not wrinkle easily. There are two types of methane foam: hot-cured urethane foam, which requires high processing temperatures, and cold-cured urethane foam, which requires low processing temperatures. The processing temperature for cold-cured urethane is generally around 60° C., and although a highly elastic foam can be obtained, the cost is high because it has a high density and requires crushing. On the other hand, the processing temperature for Hot Kiko and Aurethane is 120°C to 130°C.
It is easier to create a frame with a lower density than cold cure urethane, the material cost is low, and since a club sink is not required, it is easy to foam the frame integrally with the frame embedded in the pad, etc. There are advantages. However, with hot-cured urethane that is treated at high temperatures, the mold release agent is more likely to migrate to the urethane surface than with cold-cured urethane, and therefore, even if you try to adhere the skin to the urethane pad after molding, the release agent that remains on the pad surface will remain. It was difficult to adhere the epidermis using the molding agent. Therefore, the present inventors focused on using a film that is releasable to urethane resin, such as polyfluorinated ethylene resin (trade name: Teflon), instead of a mold release agent. In this case, the above film is placed on the molding surface of a mold kept at a predetermined temperature, and the urethane foam stock solution is injected onto it to foam and harden.Then, after the film is peeled off, the skin is attached with an adhesive. A process such as gluing is used. [Issues to be solved by the invention@] When using a film that has releasability to urethane resin as described above, the urethane may not be cured well, and an investigation of the causes revealed the following. Understood. Conventional molds for molding urethane foam indirectly heat the molding surface by blowing a heat medium such as high-temperature steam into the mold to maintain the urethane processing temperature. If the film is simply placed on the molding surface, the film cannot be brought into sufficient contact with the molding surface, so that a heat insulating space may be created between the film and the molding surface. Moreover, since the polybutylene resin film has high heat insulation properties, the thermal conductivity between the molding surface and the urethane foam becomes even worse. Therefore, when urethane foam is molded using a mold in this condition, the heat from the temperature-controlled mold cannot be sufficiently transferred to the urethane foam, making it difficult to control the processing temperature accurately. Therefore, an object of the present invention is to be able to accurately control the processing temperature of urethane foam while using a film instead of a mold release agent, and to mold hot-cured urethane foam without using a mold release agent. [Means for Solving the Problems] The mold of the present invention developed to achieve the above object has a chamber formed inside the mold and connected to an exhaust means. a molding surface on which a film having a melting temperature of 120° C. or higher and non-adhesive to urethane resin is set; and a molding surface formed on the molding surface and communicating with the chamber to suppress the negative pressure generated in the chamber. A small hole that acts on the film to attract and hold the film on the molding surface, and a direct heating means that is disposed along the molding surface and directly heats the molding surface to the processing temperature of the urethane resin. Equipped with

[Function] The above film is set on the molding surface of the mold, and by generating negative pressure in the chamber in the mold using the exhaust means, the film is adsorbed to the molding surface through the small holes in the molding surface, and the film is Shape and hold in a specified shape. By injecting a urethane resin stock solution onto this film and carrying out foam molding, a urethane molded article with the above film adhered to it can be obtained. This urethane molded product can be easily released from the mold because the film is present at the interface with the mold. If the film adhering to the surface of the urethane molded product is peeled off after the mold release, the surface can be bonded. [Example 1] An example of the present invention will be described below with reference to the drawings. The automobile seat 1 shown in FIG. 2 includes a pad 2 which is a molded product of hot-cured urethane foam molded into a predetermined shape, and a skin 3 that covers the outside of the pad 2.
An adhesive 41 is used to bond the skin 3 to the pad 2. Note that a well-known seat frame may be embedded inside the pad 2. Hollow molding die 10 shown in FIGS. 1 and 3, etc.
is equipped with a chamber 11 inside. This chamber 11 has an exhaust device 12 as a negative pressure generation source.
is connected. A molding surface 13 corresponding to the product shape of the pad 2 is provided on the upper surface side of the mold 10 in the drawing. On this molding surface 13, the melting temperature is 120°C or higher, that is, the
A polyfluorinated ethyl-1 non-resin film 14 is set as an example of a resin film that has a temperature equal to or higher than the curing temperature of the hot-cure urethane resin and has non-adhesive properties to the urethane resin. Further, a large number of small holes] 5 are formed on the molding surface 13. These small holes 15 are connected to the chamber 161. By applying the negative pressure generated in the chamber 11 to the film 14, the film 4 can be attracted to and held on the molding surface 3. Along the inner surface of the mold wall 16 of the molding surface 13, a heat medium pipe 17 as an example of direct heating means is arranged. This piping 17 is provided with a pipe 12 so that high-temperature steam, which is an example of a heating medium, is supplied from a steam supply source 18 to directly heat the molding surface 13 to the processing temperature of the urethane foam. In addition, by arranging an electric heater instead of the heat medium pipe 17, the mold wall 16 can be heated to the above temperature by 1f.
17 may also be used for direct heating. The manufacturing process of the sheet 1 is as follows. As shown in FIG. 3, the film 14 is set on the molding surface 13 of the mold 10. Then, as shown in FIG. 4, by reducing the pressure in the chamber 1 and applying negative pressure to the molding surface 13 through the small holes 15, the film 14 is attracted to the molding surface 13 and molded into a predetermined shape. At this time, the heat medium pipe 17
Since the molding surface 13 is heated through the molding surface 13 and the film 14 is softened, the film 14 can be easily plastically deformed along the shape of the molding surface 13. Further, the film 14 can be preheated to around the processing temperature (120° C. to 130° C.) of the 1-notane resin through the heated molding surface 13. As mentioned above, since the film 14 is adsorbed and held on the molding surface 13 prior to foam molding of the urethane resin, the generation of a heat insulating space due to the accumulation of air between the molding surface 13 and the film 14 is prevented. It can be prevented. Furthermore, since the film [4] is completely in close contact with the entire surface of the molding surface 13, even if the film 14 has low thermal conductivity, the heat from the molding surface 13 can be efficiently transferred to the urethane resin. Note that the film 14 may be formed into a predetermined shape in advance. As shown in FIG. 5, an intermediate mold 21 is placed on the mold 10.
At the same time, set the upper mold 2 as a lid on top of it.
Cover with 2. The pressure in the chamber 11 is continued to be reduced, and the film 14 is adsorbed onto the molding surface 13. Note that the negative pressure may be released after the film [4] is held in the holding state; At this time, there is also a method of holding the film 14 on the inner surface of the mold 0 using an adhesive. Into the cavity 23 surrounded by the mold 10, 21, 22, a stock solution 24 of hot glue and urethane foam is injected through a nozzle 25, reacted and hardened, and a pad 2 of urethane foam is obtained. In this case, since the molding surface 13 is covered with a film 14 instead of a mold release agent, the pad 2 is covered with the film 14.
Cured on 4. The film 4 made of a polyphenylene-free resin can be easily peeled off from the molding surface 13. There is no need to apply a mold release agent to the molding surface 13 in sub-2. Intermediate money! ff21 and 1: M type agent may be applied to the mold 22. After releasing Bad 2 from the mold, film]
Peel off 4, and then add an example of adhesive 4 and 1. At the same time as covering the skin with a hot melt film, the epidermis 3
By covering it with and heating it to the melting temperature of the adhesive material 4,
A skin 3 is integrally bonded to the surface of a pad 2. Note that the resin film 14 described above has a melting temperature of 12
A hot-melt adhesive film having a temperature of 0° C. or higher (hot-melt adhesive film or higher than the processing temperature of hotkico or urethane) may be used. In this way, by leaving the film 14 as it is on the surface of the pad 2 after the mold release, the film 14 can be used as an adhesive for bonding the surface. Further, the film 14 may be made of polyethylene or polypropylene having a melting temperature of 120° C. or higher. The skin-integrated sheet obtained through the above process has the skin 3 firmly integrated with the pad 2, so it does not wrinkle even if used repeatedly, has high durability 1, and has a good design. Are better. Since there is no need to apply a mold release agent to the molding surface 13, the release agent does not inhibit or cause adhesion when adhering the skin 3, and hot cure urethane (skin integral molding) is now possible. [Effects of the Invention] By using the mold of the present invention, hot-cured urethane suitable for integral skin molding can be produced without using a mold release agent.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a perspective view showing a part of gold 1, Fig. 2 is a cross-sectional view of the sheet integrally molded with the skin, and Fig. 3
The figure is a cross-sectional view showing the mold and film, and Figure 4 shows the film adsorbed to the molding surface! . FIG. 5 is a cross-sectional view showing one part into which the urethane stock solution is injected, and FIG. 6 is a cross-sectional view of a molded urethane knot. DESCRIPTION OF SYMBOLS 1... Automobile seat, 2... Pad, 3... Outer skin, 4... Adhesive material, 1o... Molding mold, 11...
- Chamber, 12... Exhaust device, 13... Molding surface,
14... Film, 15... Small holes, 17... Heat medium piping (direct heating means), 24... Urethane stock solution.

Claims (1)

[Claims] A hollow mold used when foam-molding hot-cured urethane resin, comprising: a chamber formed inside the mold and connected to an exhaust means; A molding surface on which a film that is non-adhesive to resin is set; and a molding surface formed on the molding surface and communicating with the chamber, by applying negative pressure generated in the chamber to the film. A hot mold characterized by comprising a small hole that attracts and holds the molding surface, and a direct heating means that is arranged along the molding surface and directly heats the molding surface to the processing temperature of the urethane resin. Mold for molding cured urethane foam.