JP2993250B2 - Recycling method of polyurethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating a polyurethane foam, and more particularly to a method for heating and compressing a polyurethane foam to regenerate and reuse the polyurethane foam to obtain a molded sheet of a foam.

[0002]

2. Description of the Related Art As a conventional method for regenerating a polyurethane foam, for example, there is the following method. Defective products when molding polyurethane seats, burrs on molded products, etc.
Alternatively, polyurethane foam such as offcuts in the slab foam manufacturing process, burrs during foam molding, or defective products is crushed, and a polyurethane-based adhesive is applied to the obtained crushed product by spraying, and steam steam is heated. It is well known that the adhesive is cured to bond a pulverized urethane product (called a chip foam) to form in a mold. These waste urethane foams have a density of about
It is 0.03 g / cc and the foam recycled with the adhesive has a density of about 0.06 g / cc. A method is also known in which RIM urethane used in a bumper is crushed and reused for a mudguard or the like using an adhesive. Further, the present inventor has disclosed a polyurethane rubber fine powder in Japanese Patent Application No. 3-222398 to obtain a solid rubber-like elastic body having a density of 1.0 g / cc or more.
It was suggested that this could be used for mudguards and the like. Here, the density of 0.50 ~
A method for obtaining a polyurethane molded product as a foam of 0.85 g / cc was proposed.

[0003]

However, in such a conventional method for regenerating a polyurethane foam,
Since the urethane-based adhesive uses an organic solvent (such as methylene chloride), when it is heated and cured with water vapor, the organic solvent is volatilized into the atmosphere, causing air pollution or using an adhesive. A process is required, and it is difficult to control the density of the regenerated foam due to steam heat curing.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem. A polyurethane foam is pulverized to obtain a powder having a particle size of 3 to 8 mm.
Preheat at 00-180 ° C, heat at 190 ° C-210 ° C, charge a predetermined amount in the mold, control the thickness of the molded sheet according to the land height of the mold, and control the density of 0.50-0.85g / cc. The polyurethane foam can be regenerated by obtaining a molded product. That is, in the method for regenerating a polyurethane foam of the present invention, a thermosetting polyurethane foam is obtained by pulverizing a thermosetting polyurethane foam in a method for regenerating a polyurethane foam which obtains a molded article by heating and compressing after pulverizing the thermosetting polyurethane foam. Powder with a particle size of 3-8 mm
Preheat at a temperature of 180180 ° C., preferably 170 ° C. for at least 5 minutes, preferably 20 minutes, and in a mold at a temperature in the range of 190-210 ° C.,
It is characterized in that the molded product is heated and formed by controlling the thickness of the molded product with a land spacer of the mold so that the density becomes 0.50 to 0.85 g / cc.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Example 1 Remove scraps of building slab foam, or urethane waste in the factory or polyurethane foam used for seat cushions or seat backs of scrap cars from the car, remove the vinyl cover etc., remove the headrest, Next, the urethane foam of the seat cushion and the seat back was cut into a size of about 10 cm square using a band saw.

[0006] Next, except for the cloth, the reinforcing portion, and the reinforcing metal, the material was roughly pulverized by a usual pulverizer to a diameter of 5 mm to 8 mm.
Next, the ground product was dried in an oven at 170 ° C. for about 20 minutes and preheated. Next, heat the mold in advance to 190-200 ° C, fill the mold with the pulverized product, apply pressure, pressurize it until it contacts the land spacer of the mold, and heat for about 5 minutes. Thus, a molded product was obtained.

Depending on the weight of the pulverized product to be filled in the mold and the height of the land spacer of the mold, the density of the molded product is 0.50 to 0.50.
Although it is possible to change it to 0.85 g / cc, if the filling amount of the crushed product of the molding raw material is reduced in the molding die and a flat plate having a constant thickness is molded, the specific gravity becomes small, but the specific gravity during molding is reduced. Since the internal pressure of the resin is also reduced, the surfaces of the powders are insufficiently heat-sealed to lower the strength. With this hot press molding method, the density
If it is less than 0.5, it cannot be said that it is sufficient for practical strength.
If it is larger than 0.85 g / cc, a part of the molded article becomes transparent. Here, the heat fusibility of urethane foam is explained as follows. Urethane bond is 190
It is known in principle that, by dissociation at around ° C, it develops thermoplastic properties (SAE 910581).
Recycling of RIM scrapby Compression Molding).

The present invention has been made based on this chemical principle. The dissociation of the urethane bond is shown by the following equation:

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Example 2 In this example, a molded article was obtained in the same manner as in Example 1 except that the particle size of the polyurethane foam powder was changed. When the particle size of the powder is about 1 mm, about 5 mm and about 10 mm, the density is
After molding to 0.75 g / cc, the tensile strength and elongation were measured, and the obtained results are shown in Table 1. When the particle size was about 5 mm, both the strength and the elongation were large. If the particle size is about 10mm, the filling will be poor,
The molded article was uneven in density, resulting in defects, poor surface smoothness, and reduced strength.

The particle size is about 5 mm, and the density is 0.5 g / cc to 0.8 g / cc.
When changed to cc, as shown in Table 2, both tensile strength and elongation show larger values as the density increases, and the density increases to 0.85 g / c.
Above c, there is more transparency and the foam loses its properties. There are two types of polyurethane foam: HRF (high resilience foam) type, which is mainly used for the cushion side and has excellent elastic recovery, and HOT (hot mold) type, which is mainly used for the seat back (back) side. Table 3 shows the results obtained by comparing the two at a density of 0.75 g / cc. From these results, it can be seen that the strength is the same and that the HRF has larger elongation.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

Under the preheating condition at the time of molding, without preheating, moisture in the polyurethane foam evaporates into the mold at the time of molding, and the strength of the molded product is reduced. With a preheating temperature of 170 ° C,
As shown in Table 4, the preheating time was 5 minutes, 10 minutes, 20 minutes, and 30 minutes.
In terms of minutes, 20 minutes gave the best physical properties. If the time is longer than 20 minutes, the productivity is lowered and the physical properties are not improved.
When the preheating temperature was higher than 180 ° C., urethane turned yellow, indicating oxidative deterioration, and as shown in Table 5, both tensile strength and elongation were reduced. 170 ° C. is a desirable preheating temperature.

Next, as shown in Table 6, when the conditions of 190 ° C., 200 ° C. and 220 ° C. are changed,
The best physical properties were obtained at 0 ° C.

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

[Table 6]

[0019]

As described above, according to the present invention, a polyurethane foam is crushed and preheated to a particle size of about 3 to 8 mm at a temperature of 100 to 180 ° C. for 5 minutes or more, and a mold temperature of 190 to 190 ° C. A method of obtaining a molded article of a foam by charging a predetermined amount at a temperature of up to 210 ° C., performing pressure molding using a spacer having a constant thickness, and controlling the density, so that a crushed polyurethane foam is used as an adhesive. This eliminates the need for bonding, prevents air pollution due to the emission of organic solvent that dissolves the adhesive into the air, and controls the density of the foam molded product arbitrarily. And an effect that a high-strength novel polyurethane foam can be obtained.

[0020] Polyurethane foam molded articles are excellent in elastic recovery force, but are not frequently used because of expensive raw materials. However, since recycled materials can greatly reduce raw material costs, they can be bonded to carpet fabrics to adhere to floors. Available as a mat. This floor mat has soundproofing, vibrationproofing and heat insulating effects. It can also be used for dash insulators and has a soundproofing effect.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 04 105: 26

Claims (1)

(57) [Claims] 1. A method for regenerating a polyurethane foam in which a thermosetting polyurethane foam is pulverized and then heated and compressed to obtain a molded article, wherein a powder having a particle size of 3 mm to 8 mm obtained by pulverizing the thermosetting polyurethane foam. To 1
Preheat for 5 minutes or more at a temperature of 00-180 ° C and 190--21 in a mold.
A method for regenerating a polyurethane foam, which comprises heating, compressing, and molding by controlling the thickness of a molded product by a land spacer of a mold so that the temperature is in a range of 0 ° C and the density is 0.50 to 0.85 g / cc. .