JPH0150331B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an asphalt foam, and particularly to a method for producing an asphalt foam that has excellent sound absorption and sound insulation effects and high elastic strength. Joint materials used in houses, vehicles, and civil engineering work are required to have the basic properties of water repellency and slow restoring power. Products that utilize resilience have been known for a long time (hereinafter referred to as asphalt foam). However, since conventional asphalt foams are manufactured by impregnating urethane foams with open cells with molten asphalt or asphalt emulsion, there is a problem in that so-called uneven impregnation occurs and uniform quality cannot be obtained. In addition, since the asphalt attached to the cell walls of the foam due to impregnation is relatively easy to detach, there is a problem in that repeated compression causes the impregnated asphalt emulsion to gradually be lost and the quality to deteriorate. Therefore, the applicant previously proposed a method for manufacturing asphalt foam that does not cause uneven quality or deterioration of quality in Japanese Patent Application No. 57-95392 and Japanese Patent Application Laid-Open No. 58-213029. This manufacturing method involves adding and mixing 40 to 250 parts by weight of a urethane prepolymer obtained by reacting a polyether polyol with an ethylene oxide content of 15% or more with an organic isocyanate to 100 parts by weight of an aqueous asphalt emulsion. It is characterized by foaming. The reason why the amount of the urethane prepolymer added in the invention of the earlier application is set to 40 parts by weight or more per 100 parts by weight of the asphalt emulsion is that the urethane prepolymer acts as a blowing agent. This is because if the amount is less than 1 part by weight, the resulting asphalt foam will have a low expansion ratio and become too hard, making it unsuitable as a joint material. However, the inventors subsequently reexamined the production method proposed above, and found that an asphalt foam that can be used satisfactorily as a joint material even when the amount of urethane prepolymer added was less than 40 parts by weight. In addition, we discovered that this asphalt foam has excellent sound absorption and sound insulation properties due to its cellular structure containing a large amount of asphalt, making it ideal for use as automobile floor materials and dash panels, leading us to complete the present invention. It is something. That is, the present invention includes 10 parts by weight or more and less than 40 parts by weight of a urethane prepolymer obtained by reacting a polyether polyol with an ethylene oxide content of 15% or more with an organic isocyanate, with respect to 100 parts by weight of an aqueous asphalt emulsion. silicone oil
This is a method for producing asphalt foam, characterized by adding and mixing 0.5 to 3.0 parts by weight and foaming. The aqueous emulsion of asphalt used in the present invention can be obtained by known emulsion techniques, such as mechanically stirring and dispersing asphalt in water using a cationic or anionic surfactant. In this case, the asphalt may be natural asphalt, straight asphalt obtained as a residue from distillation of asphalt-based crude oil, or blown asphalt obtained by oxidative polymerization by introducing heated air into this asphalt. Further, the ratio of asphalt to water is preferably 0.3 to 2.0 parts by weight of water to 1 part by weight of asphalt. If the water content is less than 0.3 parts by weight, it is difficult to obtain a uniform emulsion;
On the other hand, if it exceeds 2.0 parts by weight, the amount of asphalt will be so small that it will not be possible to obtain an asphalt foam with the desired properties. The urethane prepolymer used in the present invention not only serves as a blowing agent, but also remains in the asphalt foam and functions as a connecting material or filler. The reason why a reaction product of a polyether polyol with an ethylene oxide content of 15% or more and an organic isocyanate is used as the urethane prepolymer is because the asphalt component is added as an aqueous emulsion as described above. This is because the urethane prepolymer is required to have good affinity with water, and the above-mentioned urethane prepolymer satisfies this requirement. The reason why the amount of the urethane prepolymer added is less than 40 parts by weight per 100 parts by weight of the asphalt emulsion is as described above. On the other hand, the reason why the amount of the urethane prepolymer added is set to 10 parts by weight or more is because a sufficient foaming ratio cannot be obtained if the amount is smaller than this. In addition, since the production method of the present invention produces an asphalt-rich product, particularly by implementing it in a mold type, it is possible to achieve further improvement in workability and joint effect. The silicone oil in the present invention acts as a foam stabilizer, and commonly used silicone foam stabilizers can be used. Further, the amount of silicone oil added is set to 0.5 to 1.5 parts by weight because if it is less than 0.5 parts by weight, there is no foam regulating effect, and if it is more than 1.5 parts by weight, the foaming effect will be suppressed. In the present invention, when the above aqueous asphalt emulsion, urethane prepolymer and silicone oil are mixed and stirred, the urethane prepolymer causes a polymerization reaction and polyurethane linkages grow, and the water in the asphalt emulsion and the urethane prepolymer The free isocyanate groups therein react as described below to generate carbon dioxide gas, resulting in a foaming action. -N=C=O+H ₂ O→-NH ₂ +CO ₂ The asphalt particles are uniformly dispersed throughout by the bubbling action of the carbon dioxide gas generated above and the mechanical mixing operation by stirring, so the obtained asphalt foam Unlike conventional methods, there is no local unevenness in the distribution of asphalt particles, and uniform quality can be obtained. Furthermore, in the asphalt foam obtained by the present invention, since the asphalt itself constitutes the foam base, the asphalt is not separated from the foam base unlike the conventional asphalt foam in which a synthetic resin foam is impregnated with asphalt. Never. Therefore, there is no deterioration in quality and it has excellent durability. Furthermore, in addition to the above-mentioned basic effects, since the asphalt foam produced according to the present invention has a cellular structure containing a large amount of asphalt, it has excellent sound absorbing and sound insulating properties. Therefore, it is suitable for use as flooring materials for vehicles, sound absorbing materials, building materials, etc. Incidentally, when the water contained in the aqueous asphalt emulsion is insufficient due to the foaming action of the urethane prepolymer, a necessary amount of water may be appropriately added and mixed. It goes without saying that fillers such as aluminum hydroxide, clay, and calcium carbonate, and additives such as pigments, rust preventives, and mold preventive agents may also be optionally added. Examples of the present invention will be described below. Examples 1 to 3 (1) 50 parts by weight of blown asphalt, 50 parts by weight of water, and 0.3 parts by weight of sodium alkyl sulfate as a surfactant were mixed using a homogenizer (mixing and dispersing machine).
The mixture was uniformly mixed and dispersed to obtain an aqueous asphalt emulsion. (2) Polyether polyol (molecular weight 3000, trifunctional) with an ethylene oxide content of 60% and tolylene diisocyanate were reacted at 85°C for 4 hours with stirring, resulting in 9.5% free isocyanate groups.
A urethane prepolymer was obtained. (3) The aqueous asphalt emulsion obtained above and the urethane prepolymer were mixed and foamed in the ratio shown in Table 1 below to produce three types of asphalt foams (Examples 1 to 3). In the same table, the specific gravities of the asphalt foams obtained in Examples 1 to 3 are also listed.

[Table] The asphalt foams obtained in Examples 1 to 3 all had water repellency and slow restoring power suitable for use as joint materials. As detailed above, according to the present invention, remarkable effects such as being able to manufacture an asphalt foam having excellent sound absorbing or sound insulating properties without causing unevenness or deterioration in quality can be obtained.

Claims (1)

[Claims] 1. 10 parts by weight or more and less than 40 parts by weight of a urethane prepolymer obtained by reacting a polyether polyol with an ethylene oxide content of 15% or more with an organic isocyanate per 100 parts by weight of an aqueous asphalt emulsion. A method for producing asphalt foam, which comprises adding and mixing 0.5 to 3.0 parts by weight of silicone oil and foaming. 2. The method for producing asphalt foam according to claim 1, wherein water is added in an amount necessary for the foaming action of the urethane prepolymer. 3. The method for producing asphalt foam according to claim 1 or 2, characterized in that fillers, foam stabilizers, pigments, and other additives are also added and mixed together.