JPH0116422B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to the production of a regeneration solution from the asphalt foam previously proposed by the applicant, particularly its cutting waste and defective molded products, and the regeneration solution and the asphalt foam having open cells. The present invention relates to a method for producing recycled asphalt foam from polyurethane foam.

[Technical background of the invention]

Conventionally, urethane foam with open cells is impregnated with molten asphalt or asphalt emulsion to provide the water repellency and slow multiplicity required for joint materials as joint materials for houses, vehicles, and civil engineering works. It is widely used (hereinafter, a product that has the water repellency of asphalt and the multidimensional strength of foam will be referred to as asphalt foam). However, conventional asphalt foam has the problem of not being able to obtain uniform quality due to so-called uneven impregnation, and when repeatedly compressed, the asphalt attached to the cell walls of the foam is gradually lost due to impregnation, resulting in poor quality. There was a problem with the decrease in

Therefore, the applicant has previously proposed a method for producing asphalt foam that does not cause quality unevenness or quality deterioration. This production method is characterized by adding and mixing a urethane prepolymer obtained by reacting a polyether polyol with an ethylene oxide content of 15% or more with an organic isocyanate to an aqueous asphalt emulsion and foaming the mixture. be. The urethane prepolymer used was specifically limited because the asphalt component is added as an aqueous emulsion, so the urethane prepolymer in this case is required to have good affinity with water. This is because it satisfies this requirement.

In this case, when the aqueous asphalt emulsion and urethane prepolymer are mixed and stirred, the urethane prepolymer undergoes a polymerization reaction and polyurethane linkage grows, and the water in the asphalt emulsion and the free isocyanate groups in the urethane prepolymer are It reacts as shown below to generate carbon dioxide gas, resulting in a foaming effect.

-N=C=O+H ₂ O→-NH ₂ +CO ₂ Then, asphalt particles are uniformly dispersed throughout by the foaming action of the carbon dioxide gas generated above and the mechanical mixing operation by stirring, resulting in uniform quality. Moreover, since the asphalt itself constitutes the foam base, the asphalt does not separate from the foam base and cause quality deterioration as in the past, and has excellent durability.

When the applicant began research on the manufacturing method according to the above invention, his main interest was in asphalt foam as a joint material. However, as a result of various studies conducted on the asphalt foam obtained by the above-mentioned manufacturing method, it was found that this asphalt foam has a cellular structure with a large amount of asphalt component, and has excellent sound absorption and sound insulation properties. It was found that there were. Therefore, the asphalt foam obtained by the above-mentioned manufacturing method can be suitably used as an automobile floor material or a dash panel, and research in this field is currently being actively continued.

By the way, when the asphalt foam obtained by the above manufacturing method is used for specific purposes such as joint material or flooring material for automobiles, the asphalt foam that has been foam-molded into a large block is generally used in a suitable manner. It is used by slicing it into thick sheets, and in some cases, it is further cut into various shapes or punched. For this reason, a large amount of processing waste is generated before the final product is made, and products with poor surface properties such as the epidermis and hypodermis of asphalt foam blocks and defective products generated during foam molding. There is a considerable amount of defective products that cannot be replaced. Therefore,
As an effective method to effectively utilize processed scraps and defective products that have no choice but to be disposed of,
The applicant has already proposed a method for recycling these processing cutting waste and defective products from foam molding into raw materials for producing similar asphalt foam again.

That is, the above regeneration method previously proposed by the applicant is
The asphalt foam is added to a solution prepared by adding an amine catalyst, a tin catalyst, or an alkaline substance to a phosphoric ester plasticizer, either singly or in combination, and dissolved while heating and stirring.

The asphalt foam obtained by the method described above contains polyurethane linkages, but when the above-described recycling method is applied, the asphalt foam is dissolved and the polyurethane linkages are cut and decomposed. Therefore, the obtained regenerated solution can be used as a raw material when producing asphalt foam again by the same method.

[Purpose of the invention]

As described above, asphalt foam produced by the production method proposed by the applicant can be regenerated into asphalt foam by the same production method via a regeneration solution, but this regeneration route does not require the foaming process to be performed again. Must be implemented.

On the other hand, the regeneration solution contains, in addition to asphalt, a phosphoric acid ester plasticizer used as a solvent and a urethane decomposition solution, and therefore has a feature of high affinity for polyurethane foam. Therefore, the present invention provides a method for producing high quality recycled asphalt foam without performing a foaming process by utilizing the properties of this recycled solution.

[Summary of the invention]

The method for producing recycled asphalt foam according to the present invention involves adding and mixing a urethane prepolymer produced by the reaction of a polyether polyol with an ethylene oxide content of 15% or more with an organic isocyanate to an aqueous asphalt emulsion and foaming the foam. The asphalt foam is added to a solution containing a phosphoric acid ester plasticizer and an amine catalyst, a tin catalyst, or an alkaline substance added alone or in combination, and the asphalt foam is dissolved under heating and stirring to create a regenerated asphalt foam solution. After the preparation, a polyurethane foam having open cells is impregnated with appropriate amounts of both the regenerating solution and the organic isocyanate, and then heated and cured.

In preparing the asphalt foam regeneration solution in the present invention, first, 100 parts by weight of a phosphoric acid ester plasticizer (triaryl phosphate is particularly suitable) and an amine catalyst (triethylenediamine, triethanolamine, triethylamine, etc.) are added. ), tin catalyst (sternus octoate,
Prepare a solution in which 0.5 parts by weight or more of dibutyltin dilaurate, etc.) or alkaline substances (aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, etc.) are added alone or in combination. Subsequently, asphalt foam is added to the solution and dissolved by heating and stirring. At that time, it is best to add the asphalt foam little by little in the form of small pieces. In addition, the heating temperature varies depending on the amount of asphalt foam added and the type of catalyst, but is generally approximately 150℃ to 250℃.
It is ℃.

Asphalt foam pieces are added and stirred while heating to a constant temperature, they gradually decompose into a liquid state, and the desired regenerated solution is obtained. In that case, the amount of asphalt foam particles added depends on the concentration of the regeneration solution to be obtained, but as a rough guide,
The range is preferably up to 800 parts by weight per 100 parts by weight.
If a larger amount is added than this, the decomposition will not proceed as expected, and the obtained regenerated solution will also tend to solidify significantly when cooled to room temperature.

After preparing the regeneration solution as described above, the present invention impregnates the regeneration solution and organic isocyanate into an open-celled polyurethane foam. As this organic isocyanate, 4,
In addition to 4-diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, etc., prepolymers having terminal NCO groups can be used. At that time, the organic isocyanate may be mixed into the regeneration solution and impregnated, or may be impregnated separately after being impregnated with the regeneration solution. In any case, the regeneration solution to be impregnated should be liquefied at a temperature of approximately 70°C to 150°C, and
Adjust the viscosity. In addition, in order to improve the physical properties of the product such as rigidity and flame retardance, fillers such as calcium carbonate and aluminum hydroxide may be added as necessary, or asphalt may be blended as a modifier. . When using asphalt as a modifier, blending with one with high penetration will make the product soft, and blending with one with low penetration will make the product harder and less sticky.

The amount of regeneration solution and organic isocyanate impregnated varies depending on the physical properties of the target product and the density of the urethane foam used, but it is recommended that the regeneration solution and organic isocyanate be at least 150 parts by weight per 100 parts by weight of the polyurethane foam.
The amount of organic isocyanate is preferably 5 parts by weight or more. When impregnating by mixing the regeneration solution and organic isocyanate, the mixing ratio is 1:0.005~
Around 40 is good.

As a method for impregnating the polyurethane foam with the regeneration solution and organic isocyanate, a dipping method in a bathtub, a spray method, a transfer method, etc. can be used, but as mentioned above, heating is required to adjust the viscosity, so transfer Particularly preferred is the method or immersion method.

After the above impregnation treatment is completed, the product is heated and cured in an oven or the like. By this heat treatment, a portion of the impregnated organic isocyanate foams to make the cells denser, and the stickiness of the product is eliminated. In addition, foaming can also be promoted using heating in a steam oven if necessary.

The quality of the recycled asphalt foam produced by the above-mentioned method of the present invention is deteriorated compared to that produced by impregnating it with solution asphalt, etc., because the impregnated regenerating solution has good affinity for polyurethane foam. It has excellent quality, as it does not cause any problems, has a dense cell structure due to the foaming of the organic isocyanate, and eliminates surface stickiness.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

Example (1) Production of asphalt foam 50 parts by weight of blown asphalt, 50 parts by weight of water, and 0.3 parts by weight of sodium sulfate as a surfactant were uniformly mixed and dispersed using a homogenizer (mixing/dispersing machine) to prepare an aqueous asphalt emulsion. Obtained.

Apart from this, ethylene oxide content 60
% polyether polyol (molecular weight 3000, 3
(functional) and tolylene diisocyanate were reacted at 85° C. for 4 hours with stirring to obtain a urethane prepolymer containing 9.5% of free isocyanate groups.

Next, 30 parts by weight of the above-mentioned urethane prepolymer was mixed with 100 parts by weight of the aqueous asphalt emulsion obtained above, foamed, and the specific gravity
Obtained an asphalt form of 0.15.

(2) Production of regeneration solution 1000 g of phenyl diisopropylphenyl phosphate and 15 g of dibutyltin dilaurate were weighed and placed in a stainless steel container, and heated to 160° C. using a heater. Into this decomposition solution, 1500 g of the asphalt foam pieces obtained above were added little by little with stirring and dissolved. The final temperature was 190°C.

The asphalt foam regeneration solution thus obtained was a highly viscous liquid at room temperature.

(3) Production of recycled asphalt foam As shown in the attached drawing, the recycled asphalt foam solution 2 produced as described above is
1 in a dipping tank and heated to 90℃.
Density 0.020 g/cm ³ and thickness 10 mm in the regeneration solution bath
A flexible polyurethane foam sheet 10 was dipped to impregnate it with the regeneration solution. At this time, the regenerating solution is sufficiently absorbed and impregnated into the re-expanding polyurethane foam 10 by being once compressed by a pair of immersed rolls 3 ₁ and 3 ₂ placed in the regenerating solution 2 .

Subsequently, by passing through squeeze rolls 4 ₁ and 4 ₂ placed at the upper end of the dipping tank 1 and pulling it out, the amount of impregnated regenerating solution was adjusted to 260 parts by weight per 100 parts by weight of the soft polyurethane foam. .

Next, the organic isocyanate filled in the isocyanate bath 5 is applied to the polyurethane foam 10 via transfer rolls 6 ₁ , 6 ₂ , and the applied organic isocyanate is further passed through compression rolls 7 ₁ , 7 ₂ . was evenly impregnated.

Thereafter, it was introduced into a steam oven heated to 80°C and cured by heating to obtain a recycled asphalt foam 10'.

The recycled asphalt foam obtained in the above example had the characteristics of an asphalt foam, such as a slow reproduction speed and excellent sound absorbing and sound insulating properties. Moreover, the stickiness on the surface was almost completely eliminated.

〔Effect of the invention〕

As described in detail above, according to the present invention, the processing waste of asphalt foam manufactured by the method proposed by the previous applicant and the defective products during foam molding are used as a regeneration solution, and the foaming process is carried out from the regeneration solution. Remarkable effects such as the ability to produce high-quality recycled asphalt foam without the need for reprocessing can be obtained.

[Brief explanation of drawings]

The attached drawing is an explanatory diagram showing a recycled asphalt foam manufacturing apparatus used in one embodiment of the present invention. 1... Impregnation tank, 2... Regeneration solution, 3 ₁ , 3 ₂ ...
Impregnation roll, 4 ₁ , 4 ₂ ... Squeezing roll, 5 ... Isocyanate bath, 6 ₁ , 6 ₂ ... Transfer roll, 7 ₁ ,
7 ₂ ... Compression roll, 8... Heating oven.

Claims (1)

[Claims] 1. Asphalt foam obtained by adding and mixing a urethane prepolymer produced by the reaction of a polyether polyol having an ethylene oxide content of 15% or more with an organic isocyanate into an aqueous asphalt emulsion and foaming the mixture. , a phosphoric acid ester plasticizer, an amine catalyst, a tin catalyst,
Alternatively, a regenerated solution of asphalt foam is prepared by adding an alkaline substance alone or in combination to a solution and dissolving it while heating and stirring, and then both the regenerated solution and the organic isocyanate are added to a polyurethane foam having open cells. 1. A method for producing recycled asphalt foam, which comprises impregnating an appropriate amount of and heating and curing the foam. 2. The method for producing recycled asphalt foam according to claim 1, wherein the polyurethane foam having open cells is impregnated with the polyurethane foam having open cells and then impregnated with the organic isocyanate. 3. The method for producing recycled asphalt foam according to claim 1, characterized in that the regenerating solution and the organic isocyanate are mixed in advance, and the polyurethane foam having open cells is impregnated with this mixed solution. .