JPH0784015B2 - Method for producing polyurethane foam - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyurethane foam.

[Prior Art] Conventionally, a urethane foam slab is a urethane foam that is foam-molded into a large block shape. By slicing this into a desired thickness or cutting it into a desired shape, it is used for vehicle interior materials and vehicles. Widely used as a cushion material.

By the way, as a method for producing a polyurethane foam, as shown in FIG. 5, a method for producing a polyurethane foam slab 2 by injecting a polyurethane foaming undiluted solution into a large container (foaming tank) 1, foaming it, and curing it. It has been known. In this case, it is usual to cover the inner surface of the foaming tank 1 with a release paper (not shown) to perform the foaming operation. According to such a batch-type manufacturing method, it can be carried out in a relatively narrow place. Further, this method has an advantage that a slab having an arbitrary shape can be manufactured by changing the shape of the foaming tank 1.

[Problems to be Solved by the Invention] However, the conventional batch-type manufacturing method has the following problems.

That is, when the polyurethane foaming stock solution is stirred and poured into the foaming tank 1, the foaming reaction proceeds, and the liquid surface gradually rises.
At this time, the viscosity of the stock solution that rises increases as the foaming reaction proceeds, so that foaming is hindered by the frictional resistance with the inner surface of the foaming tank in the vicinity of contact with the foaming tank 1. Therefore, the polyurethane foam slab 2 after the completion of foaming has a shape that is high in the center of the slab and low in the peripheral portion, as shown in FIGS. 5 and 6, and a flat top surface cannot be obtained.

As a result, as shown by the chain double-dashed line in FIG. 5, the convex apex of the obtained slab 2 must be cut out to a predetermined size, resulting in a waste portion or an increase in the number of steps. There was a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a polyurethane foam that can obtain a slab having a flat top surface when producing the polyurethane foam slab.

[Means for Solving Problems] In the present invention, after the polyurethane foaming stock solution is stirred and mixed and injected into the foaming tank, the foaming rise of the foaming stock solution is started. The gist is to place a weight with a flat back surface in the foaming tank from the upper part at any position to complete the foaming rise.

[Operation] According to the present invention, the polyurethane foam foaming stock solution, which is appropriately mixed and stirred, is injected into the foaming tank, and then the foaming rise (rise) of the foaming stock solution is started, which is completed when the foaming rise proceeds by about 70%. Immediately before, a polyurethane foam slab with a flat top surface can be obtained by placing a weight with a flat back surface in the foaming tank from the top to complete foam rise. Therefore, it is possible to eliminate a wasteful slab and omit the cutting step without cutting the convex top portion to a predetermined shape as in the conventional case.

In the present invention, as the material of the weight, various materials such as metal and plastic are used. However, in order to release the gas (carbon dioxide gas) due to the foaming reaction, an open-cell foam sheet such as a polyurethane foam sheet is used on the back surface of the weight. Is preferred.

The weight of the weight is not generally determined depending on the rate of rise of the foaming stock solution, the strength of gelation of the foam, and the size of the foaming tank, but is preferably about 0.5 to 2.0 g / cm. Here, if the weight is too heavy, foaming is suppressed and at the same time the foaming reaction is inhibited, causing cracks and the like. On the other hand, if it is too light, the weight of the foaming undiluted solution will be lifted as it is and will not be flat.

In the present invention, the polyurethane foam foaming stock solution is a polyol such as polyether polyol or polyester polyol, an organic isocyanate such as tolylene diisocyanate, an amine catalyst, a tin catalyst, a foaming agent (water), a foam stabilizer (silicone oil), and other pigments. The fillers and the like are used in an appropriate combination according to the required characteristics.

In the present invention, a weight is used anywhere after the foaming rise has progressed by about 70% and immediately before completion, which results in a foaming rise of 70% or more.
If it is less than%, the gelation is weak and the weight cannot be supported enough to hinder the foaming reaction.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Here, FIG. 1 is a polyurethane foam manufacturing apparatus according to the present invention, FIG. 2 is a perspective view of a foaming tank according to the apparatus, and FIG. 3 is an explanatory view of the operation of the foaming tank.

Reference numeral 11 in the figure is a cylindrical foaming tank having an open top. A frame 12 is provided on the foaming tank 11. The frame 12 is provided with a rotary shaft 14 having a sprocket 13 attached at a predetermined position. On the sprocket 13,
One end extends to the outside of the foaming tank 11 and the balancer is attached to its tip.
Three chains 16 suspending 15 are engaged. The other ends of these chains 16 are mounted in a well-balanced manner on the upper surface side of the weight 17 having a flat rear surface arranged in the foaming tank 11. A polyurethane foam sheet (not shown) is attached to the back surface of the weight 17. The side wall of the foaming tank 11 is provided with an undiluted foaming liquid introducing port 11a, and the introducing port 11a is provided with a door 18 which can be opened and closed.

A rail 20 is attached near the foaming tank 11.
A carriage 22 having wheels 21 on its legs is placed on the rail 20, and can be moved toward and away from the foaming tank 11 by expanding and contracting the pushing cylinder 23. A rotating shaft 24 is horizontally stretched around the carriage 22, and a cylindrical mixing and stirring tank 25 is pivotally fixed to the rotating shaft 24. The rotating shaft 24
Is rotated by a motor and an irregular gear (not shown), whereby the mixing and stirring tank 25 is tilted in the direction shown by the arrow in the drawing. A stirring blade 26 is provided inside the mixing and stirring tank 25 in the axial direction thereof, and the stirring blade 26 is rotationally driven by a motor 27 attached below the mixing and stirring tank 25. Also,
At the lower end portion of the side surface of the mixing and stirring tank 25, a foaming liquid discharge pipe 28 extends obliquely downward. This foaming liquid discharge pipe 28
The mixing and stirring tank 25 and the mixing and stirring tank 25 are communicated with each other via a solenoid valve 29 provided at the boundary between the two. Furthermore, the mixing and stirring tank 25
A measuring tank 30 for the organic isocyanate component is arranged on the upper part of the container, and the measuring tank 30 is connected to an organic isocyanate supply source through a pipe 31. A raw material supply pipe 32 is provided at the lower end of the measuring tank 30, and an electromagnetic valve 33 is provided between the raw material supply pipe 32 and the measuring tank 30. Further, a polyurethane foam raw material supply pipe 34 other than an isocyanate component such as a polyol or a catalyst is connected to the raw material supply pipe 32.

The organic isocyanate component measuring tank 30 is additionally provided with a cleaning solvent supply pipe 35 for polyurethane foam raw material, and the supply pipe 35 is connected to a cleaning solvent tank 36. Also,
A cleaning solvent waste liquid receiver 37 is installed, and this waste liquid receiver 37 is connected to the cleaning solvent tank 36 via a pump 38.

Next, the operation of the manufacturing apparatus having the above structure will be described.

First, the extrusion cylinder 23 is expanded and contracted, and the polyurethane foam foaming stock solution is adjusted with the mixing and stirring tank 25 retracted from the foaming tank 11. That is, after the organic isocyanate component is supplied from the pipe 31 into the measuring tank 30 for measurement, the solenoid valve 33 is opened to supply the predetermined amount of the isocyanate component from the raw material supply pipe 32 into the mixing stirring tank 25. At the same time, other raw materials such as the polyol component and the catalyst are put into the mixing and stirring tank 25 through the pipe 34. Subsequently, the stirring blade 26 is rotated to mix uniformly.

Next, the extrusion cylinder 23 is driven to expand and contract to advance the mixing and stirring tank 25 to the position shown in the figure, and the tip of the foaming stock solution discharge pipe 28 is inserted into the foaming tank 11 from the foaming stock solution inlet 11a. At that time, the door 16 is pushed by the foaming stock solution discharge pipe 28 and easily opened. Then, open the solenoid valve 29 to discharge the foaming stock solution adjusted in the mixing and stirring tank 25.
It is poured into the foaming tank 11 through 28. At that time, the rotating shaft 24 is rotated as necessary, and the mixing and stirring tank 25 is tilted forward to promote the outflow of the foaming stock solution.

After this, the mixing cylinder 25 is retracted by contracting the pushing cylinder 23, and the door 16 is closed. At this time, the state of the foaming stock solution in the foaming tank 11 is as shown in FIG. 3 (a). Then, in the foaming tank 11, the foaming reaction of the polyurethane foaming stock solution and the foaming rise thereby proceed.
After a while, for example, when the foam rise progresses by about 70%, the weight located above in the foam tank 11 is dropped downward as shown in FIG. 3 (b). As a result, in the foaming tank 11, the foaming undiluted solution pushes up the weight 17 and the rise progresses to obtain a desired polyurethane foam slab 19 (shown in FIG. 3 (c)).

On the other hand, while the foaming of the polytan foam slab is being performed in the foaming tank 11 as described above, the mixing and stirring tank 25 and the isocyanate component measuring tank 30 retracted from the foaming tank 11
Then, the polyurethane foaming stock solution adhering to the inner surface is washed as follows. That is, the pump 38 is driven,
The cleaning solvent is supplied into the cleaning solvent tank 36, and the mixing stirring tank 25 is further filled with the cleaning solvent. Next, stirring blade 26
By rotating, the stock solution for foaming adhering to the inner wall of the mixing and stirring tank 25 is dissolved, and then the electromagnetic valve 29 is opened to discharge the cleaning solvent. When the cleaning solvent is discharged, the foaming stock solution adhering to the inner wall of the discharge pipe 28 is also dissolved. The cleaning solvent discharged in this way is stored in the waste liquid receiver 37 and then sent to the cleaning solvent tank 36 by the pump 38 for reuse.

When the washing is completed, the next foaming raw material is prepared in the same manner as described above. The foam tank 11 is pulled out by rotating a turntable (not shown), and another foam tank is installed at the position shown instead. Thus, the polyurethane foam slab can be continuously manufactured by repeating the same operation as described above.

Therefore, according to the above-mentioned embodiment, after the polyurethane foam stock solution is stirred and injected into the foaming tank 11, the foaming rise of the foaming stock solution is started, and the weight 17 is placed when the rise progresses by about 70%. In order to complete the rise, during the rise, the approximate center part of the foaming undiluted solution in the foaming tank 11 is suppressed by the weight 17 and the peripheral part does not come into direct contact with the weight 17, so that the rise is free, and finally The entire top surface of the foaming stock solution becomes uniform, and a cylindrical polyurethane foam slab having a flat top surface can be obtained as shown in FIG.

In the above example, the weight was placed when the rise was about 70%, but the weight is not limited to this, and the rise is about 70%.
A weight may be appropriately placed anywhere from where the process has progressed to immediately before the completion.

Further, it goes without saying that the structure of the polyurethane foam manufacturing apparatus described in the above embodiment is not limited to the structure described above.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to obtain a polyurethane foam slab having a flat top surface as compared with a conventional one, and thus to cut a convex top portion into a predetermined shape as in the conventional one. Without doing so, it is possible to provide a method for producing a polyurethane foam that can improve the yield of slabs and omit the cutting step.

[Brief description of drawings]

FIG. 1 is an explanatory view of a polyurethane foam manufacturing apparatus according to the present invention, FIG. 2 is a perspective view of a foaming tank according to the apparatus, and FIG.
(A)-(c) is explanatory drawing of the foaming state in the same foaming tank, FIG. 4 is explanatory drawing of the conventional batch type manufacturing method, FIG. 5 is a perspective view of the polyurethane foam slab obtained by the conventional method, FIG. 6 is a front view of FIG. 5, and FIG. 7 is a front view of a polyurethane foam slab obtained by the method of the present invention. 11 …… Bubbling tank, 12 …… Frame, 13 …… Sprocket, 14…
… Rotation axis, 15 …… balancer, 16 …… chain, 17 ……
Weight, 18 ... Door, 20 ... Rail, 21 ... Wheel, 22 ... Truck, 23 ... Extrusion cylinder, 24 ... Rotating shaft, 25 ... Mixing and stirring layer, 26 ... Stirring blade, 27 ... … Motor, 28 …… Foaming stock solution discharge pipe, 29, 33 …… Solenoid valve, 30 …… Measuring tank, 31…
… Piping, 32 …… Raw material supply pipe, 34 …… Raw material supply pipe, 35…
… Cleaning solvent supply pipe, 36 …… Cleaning solvent tank, 37 …… Receptor for cleaning solvent waste, 38 …… Pump.

Claims (1)

[Claims] 1. A polyurethane foaming undiluted solution is stirred and mixed into a foaming tank and then the foaming rising of the foaming undiluted solution is started. A method for producing a polyurethane foam, characterized in that a weight having a flat back surface is placed therein to complete the rise of foaming.