JPS6128496B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables the production of synthetic resin foam without using groove-shaped release paper, without slicing the obtained foam, or without any other post-processing. This invention relates to a method for producing a foam that can be used as a final product as it is.

Conventionally, to manufacture polyurethane foam and other foams, a continuous removable container made of kraft paper or thin synthetic resin plate coated with synthetic resin, wax, etc. on the inside is placed on a conveyor that moves at a constant speed. , which is run at a constant speed, and a synthetic resin foaming stock solution is discharged from a nozzle into the mold release container, and is heated to foam within the mold release container, thereby producing continuous production. The resulting large slab is then cut into lengths of 1 to 2 meters and stored for approximately 24 hours to completely cure the slab.Then, the epidermis and other defective parts are removed. It is sliced to a predetermined thickness and served as pine tresses and other cushions.

However, a number of problems have been pointed out in the conventional method for producing foams. In other words, in the past, a large slab was created and then subjected to slicing and other cutting processes, which resulted in high post-processing costs and the production of a large amount of defective material. 2000mm x height 900mm x length
Due to the large size of 2000mm, internal heat generation of 150 to 170℃ was generated during curing after the foaming reaction, and this continued for several hours, causing fire and other dangers. For example, in polyurethane foam, yellowing occurs significantly, and in particular, the commercial value of the product obtained is extremely reduced. In order to avoid these problems, various studies have been conducted to obtain foams with the final thickness dimension without the need for post-processing such as slicing. The outer skin becomes extremely hard and feels completely different from the soft interior, and the cross-sectional shape of the foam becomes sloping, making it impossible to obtain a square cross-sectional shape. When removing the release paper that made up the groove-shaped container from the foamed foam, there were various problems such as the occurrence of severe roughness on the surface of the foam. However, as in the past, large slabs are continuously produced, cut into large pieces, cured completely, and then sliced to produce the final product. This invention solves these conventional drawbacks at once, and provides a method for producing synthetic resin foam in which the foam obtained by discharging a foaming stock solution and completing the foaming reaction can be used as a final product as it is. The conveyor belt has a bottom conveyor belt made of a releasable member, and side belts that are separate from the conveyor belt and move in synchronization with the conveyor belt on both sides of the upper surface, without using a grooved release paper. A concave conveyor is formed, and at one end of the conveyor, 10% by weight or more of water is added and mixed with a urethane prepolymer made by reacting a polyether polyol containing 15 to 60% by weight of ethylene oxide with an organic isocyanate. Continuously inject the foaming stock solution made of foam to prevent the foaming stock solution from leaking from the seam between the bottom conveyor belt and the side band and cause the foaming reaction to occur. The method is characterized in that the upper surface of the foam is lightly compressed using a pressure conveyor from the point at which the formation reaction ends to the point at which the crosslinking reaction ends to form a foam having the thickness of the final product. The details of this invention will be explained below based on an illustrated embodiment.

In the figure, reference numeral 1 denotes a conveyor, on which an endless belt of Teflon sheets, stainless steel plates, and other releasable members is stretched. Reinforcing plates 2 ₁ and 2 ₂ stand upright on both ends of the upper surface of the conveyor 1, and side bands 3 1 and 3 2 made of paper or the like coated with a release agent are attached to the inside of each of the reinforcing plates 2 ₁ and 2 ₂ from a winder roll (not shown). It is fed synchronously with the speed of the conveyor, so that a concave conveyor is formed here, surrounded by both. Note that this side band may be constructed of an upright endless conveyor belt made of Teflon or the like. 4 is a nozzle for supplying a foaming stock solution, which is made by adding and mixing 10% by weight or more of water to a urethane prepolymer made by reacting a polyether polyol containing 15 to 60% of the total ethylene oxide with an organic isocyanate. After the foaming stock solution is stirred by a mixing head, it is continuously supplied to one end of the concave conveyor.
By making the stock solution to be discharged special as described above, the stock solution discharged from the nozzle 4 immediately becomes cream-like and increases in viscosity. Experiments have shown that liquid leakage from the joints can be prevented by simply arranging the side bands 3 ₁ and 3 ₂ on the top side of the conveyor 1, without having to fold a sheet of release paper into a U-shape. This was confirmed as a result. The above-mentioned special foaming stock solution has already been proposed and known by the applicant in Japanese Patent Application Laid-open No. 51-20996, and its characteristics include adding and mixing a large amount of water of 10 parts by weight or more to the urethane prepolymer. By simply leaving it to stand, the reaction begins immediately without adding any catalysts such as amines or tin, and the resulting foam has superior texture and properties to urethane foam produced using conventional methods. be. In addition, in order for the obtained foam to have the same thickness as the final product, the discharge amount of the foaming stock solution must be adjusted in advance to a predetermined amount corresponding to the thickness of the final product. 5 is a pressure conveyor that lightly compresses the upper surface of the foam from the point where the bubble generation reaction ends to the point where the crosslinking reaction ends, and is a press conveyor that lightly compresses the upper surface of the foam from the point where the bubble generation reaction ends to the point where the crosslinking reaction ends. Use sexual parts. This pressing conveyor 5 is required to lightly compress the foam from the time when the foaming gas has finished coming out from the surface of the foam and the bubble generation reaction has ended, and the upper surface of the foam must be pressed even before that point. , there is a risk that the foaming reaction itself may be suppressed, resulting in bursting of bubbles and other bubble roughness. In addition, the pressure of the foam is limited to light compression,
If more pressure is applied than necessary, uniform foam formation cannot be expected. Further, the pressure conveyor is spaced apart from the conveyor belt 1 according to the thickness of the product, and
As for the length, it is necessary to lightly compress the upper surface of the foam until the cross-linking reaction is completed, so the curing time varies depending on the thickness of the resulting foam, and cannot be determined uniformly. If you use the pine tress method, a length of about 10 meters is sufficient. It goes without saying that the pressing conveyor 5 is moved in the same direction in synchronization with the conveyor 1 forming the bottom of the concave conveyor. Furthermore, if a transfer roll is used on the pressure conveyor 5 and the conveyor 1 constituting the groove-shaped container and a release agent is applied to the surface, the mold release from the obtained foam can be done smoothly. First, the surface properties of the foam can be further improved.

According to the present invention, the discharged special foaming stock solution is lightly compressed between the releasable conveyors arranged at a distance from each other in terms of the thickness of the final product, and a foaming reaction is performed to produce the foam. The foam thus obtained not only has a rectangular cross-section, but also has a highly flexible surface that is comparable to or better than the virgin surface cut from a conventional slab. . Not only that, this method does not use release paper folded into grooves,
Even if release paper is used as the side plate, the amount used is small, and industrial waste can be prevented from being discharged compared to the conventional method in which a large amount of release paper is discharged. Of course, since curing is completed in succession with the foaming reaction, there is no internal heat generation or any risk of fire resulting from this. In addition to slicing, the resulting foam can be used immediately as it is, and manufacturing costs can be significantly reduced.

(Example) Polyurethane foam was continuously manufactured using the following formulation using the apparatus shown in the figure. However, the width of the conveyor is 1500mm, and the width between both sides of the conveyor is 1000mm.
mm, conveyor speed 2m/min, nozzle length 1m, gap between the bottom conveyor and the pressure conveyor 60mm, the bottom conveyor and side belt are separate, leaving a small gap between them, and both the bottom conveyor and the pressure conveyor are coated with silicone on top of Teflon coating. A material coated with a mold release agent was used.

Ethylene oxide content 55%, molecular weight 3300, trifunctional polyether polyol (trade name of Mitsui Nisso Co., Ltd.)
EP505S, 90 parts by weight and the company's product name MN3050,
1 part by weight of blended polyether polyol)
Add 31 parts by weight of tolylene diisocyanate to 100 parts by weight (parts by weight, same below) and heat at 90℃2.
By heating and stirring for a period of time, a prepolymer having an NCO content of 8.8% was obtained.

Next, 100 parts of the above prepolymer, 15 parts of water, and a small amount of silicone oil (foam stabilizer) were discharged from the mixing head onto the conveyor.

The product thus obtained was already in the initial stage of foaming when discharged from the nozzle, and there was no trace of water leaking from the gap between the bottom conveyor and the side band, and a foam with a square cross section with clean corners was obtained.

[Brief explanation of the drawing]

The figure is a perspective view of an apparatus according to an embodiment of the method of this invention. 1...Conveyor, 3 ₁ , 3 ₂ ...Side band, 4...
Nozzle, 5...press conveyor.

Claims (1)

[Claims] 1 A concave conveyor surrounded by a bottom conveyor belt made of a releasable member without using a grooved release paper, and side bands on both sides of the upper surface that are separate from the conveyor belt and move in synchronization with the conveyor belt. A urethane prepolymer is formed by reacting a polyether polyol containing 15 to 60% by weight of ethylene oxide with an organic isocyanate at one end.
A foaming solution made by adding and mixing 10% by weight or more of water is continuously injected to cause a foaming reaction while preventing leakage of the foaming solution from the seam between the bottom conveyor belt and the side belt. The upper surface of the foam is lightly compressed using a pressure conveyor from the point where the bubble generation reaction ends and the crosslinking reaction ends to the foam having the thickness of the final product. Characteristic method for producing synthetic resin foam.