JPS6128693B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a foamed elastic sealing material used to fill gaps in various structures such as buildings, civil engineering, vehicles, and light electrical equipment. Conventionally, as foamed elastic sealing materials, bituminous substances such as asphalt, synthetic resins such as polyacrylic esters, polyisobutylene, ethylene-vinyl acetate copolymers, and other styrene-butadiene copolymer rubbers, ethylene-propylene copolymer rubbers, etc. A liquid substance is prepared by dissolving a film-forming substance made of synthetic rubber in an organic solvent or emulsifying it in water, and this is impregnated and coated on an open foam such as polyurethane foam or polyvinyl chloride foam, and then heated. It is known to be dried. The above-mentioned film-forming substance is used to form a film on the entire pore walls of the open foam to appropriately fill the pores and exhibit waterproof properties. In this type of sealing material, the air permeability changes depending on the amount of liquid impregnated, that is, the thickness of the coating formed on the hole wall. Good results can be obtained. However, on the other hand, when the sealing material is compressed at a relatively high temperature, the impregnated material tends to flow out of the open foam due to pressure and temperature, increasing the risk of contaminating structures and workers. This tendency is particularly noticeable when the film-forming substance has adhesive properties. In addition, the weight of the sealing material itself becomes heavy, which is disadvantageous in terms of workability and economic efficiency, and it also has drawbacks such as limited application areas, inability to fully demonstrate its original sealing function, and poor appearance. come. The reason for this is obvious: as the amount of impregnation increases, the sealant itself becomes harder, making it difficult to properly follow and adhere the sealant to the uneven surface of the adherend. This is because, when applied to a body, bending failure tends to occur on the inner and outer circumferential surfaces of the sealing material, and furthermore, the compressibility is limited, making it difficult to compress and fill adherends with extremely uneven surfaces. On the other hand, in order to solve this problem, if the amount of impregnation is reduced and the thickness of the coating is made thin, the air permeability becomes large and the waterproof property becomes unsatisfactory. This invention aims to avoid the above-mentioned conventional drawbacks, and its gist is that after impregnating an open foam with a liquid material containing a heat-sensitive foaming agent and an adhesive film-forming substance, , a method for producing a foamed elastic sealing material, comprising drying the foaming agent while gasifying and foaming it by heating to form an adhesive foam coating on the pore walls of the foam. That is, in this invention, a heat-sensitive foaming agent is pre-impregnated into the liquid material to be impregnated, and the foaming agent is gasified and foamed when the open foam is impregnated with the heat-sensitive foam and then dried by heating. An adhesive foam coating is formed on the hole walls of the sealant, and since this foam coating has a foam structure, even if the thickness of the foam coating is made considerably thick, there is no need to worry about adding weight or hardness to the sealing material. Moreover, the compressibility of the sealing material is maintained at a high level. Therefore, according to the foamed elastic sealing material of the present invention provided with such an adhesive foamed coating, it is possible to exhibit the desired waterproof performance, and it is also possible to prevent run-off, contamination, and increase in weight due to excessive impregnated amount as in the past. There is no disadvantage in terms of workability or economic efficiency. In addition, since the sealant itself is flexible and has a high compressibility, and the foam coating has adhesive properties, it can adhere well to uneven surfaces of adherends, and can also adhere to curved surfaces. It has the advantage that there is less risk of bending failure during construction, and it can be compressed and filled well even to adherends with extremely uneven surfaces. It is possible to seal various adherends with good appearance and sealing function without any problems. The open foam used in this invention may be a urethane foam or other foam, and a wide range of conventionally known foams can be used as long as they have open cell properties. Typical examples include polyether-based or polyester-based urethane foams and polyvinyl chloride-based foams. The type of liquid to be impregnated into the foam may be any of the various types conventionally used as impregnating liquids, such as organic solvent-based and aqueous emulsion-based liquids. The film-forming substance to be included in this liquid must have adhesive properties, such as bituminous substances such as asphalt as already mentioned, polyacrylic esters, polyisobutylene, and ethylene-vinyl acetate copolymers. Those having adhesive properties are selected from among various synthetic resins such as , natural rubber, styrene-butadiene copolymer rubber, ethylene-propylene copolymer rubber, and other synthetic rubbers as main materials. The proportion of this film-forming substance in the liquid is usually 30 to 70.
It is about % by weight. The heat-sensitive foaming agent used together with the film-forming substance is preferably one that gives the adhesive foamed film a closed-cell structure, but it may also have an open-cell structure. Examples of blowing agents that provide a closed cell structure include azo compounds such as azodicarbonamide and azobisisobutyronitrile, nitroso compounds such as dinitrosopentamethylenetetramine, paratoluenesulfonyl hydrazide, and 4,4'-oxybis Examples include sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide. In addition, when forming an adhesive foam coating into an open-cell structure, it is generally preferable to use a foam with a low decomposition temperature, and using a foaming agent such as the one described above with a foaming aid such as an organic acid or urea lowers the decomposition temperature. It tends to have an open cell structure. The amount of the heat-sensitive foaming agent to be used depends on the type of adhesive film-forming substance and its proportion in the liquid so that the foaming ratio when heated and foamed is 1.1 to 10 times, particularly preferably 3 to 5 times. It can be set as appropriate. Generally, the amount is about 2 to 20 parts by weight per 100 parts by weight of the adhesive film-forming substance. In the present invention, any means may be used to impregnate the open foam with the above-mentioned liquid material, heat dry it, and foam it, and the impregnation step and heat drying (foaming) step may be continuous or discontinuous steps. If it is a continuous process, for example as shown in Figure 1,
The continuous foam 1 wound into a roll is introduced into a storage tank 3 for impregnating liquid material 2 via impregnating rolls 4, 4,
After impregnating an appropriate amount with the impregnation control rolls 5, 5, the heating and drying chamber 6 is connected to perform foaming and drying of the liquid medium at the same time. The amount of impregnation varies considerably depending on the type and specific gravity of the open foam, the type and viscosity of the impregnating liquid, and the intended use of the sealant, but in general, it is The solid content weight ratio is preferably 0.1 to 10 times, particularly preferably 0.5 to 5 times. As described above, the present invention is characterized in that the above-mentioned amount of impregnation can be reduced compared to the conventional method, and the thickness of the coating formed by foaming after impregnation can be increased. As a heating means in the heating drying chamber, blowing hot air or other known means can be used, but the heating temperature is set to a temperature at which the heat-sensitive foaming agent can be gasified and foamed and the liquid medium can be volatilized and removed. In FIG. 1, numeral 7 shows the state in which the foamed elastic sealing material of the present invention obtained as described above is wound into a roll. It can be effectively used as a sealing material to fill gaps in various structures such as architecture, civil engineering, vehicles, and light electrical equipment. Next, examples of this invention will be described. Example A toluene solution with a solid content of 30% by weight and a viscosity (20°C) of 500 centipoise was prepared by dissolving and mixing 100 parts by weight of butyl polyacrylate and 5 parts by weight of dinitrosopentamethylenetetramine.
0.030 polyether urethane foam (10mm
x 1000mm x 2000mm) in an impregnating liquid tank equipped with two rolls so that the solid content is 4 times the weight ratio, and then heated in a heating drying room at 140℃ for 10 minutes to gasify and foam. The solvent was removed by volatilization to obtain a foamed elastic sealing material of the present invention. The adhesive foam coating of this sealing material had a foaming ratio of 3 to 4 times, that is, a thickness of 3 to 4 times that of one not containing a foaming agent. Comparative Example Except that the foaming agent (dinitrosopentamethylenetetramine) was removed from the impregnating solution and the amount of impregnation was increased so that the coating thickness after heat drying was the same as the adhesive foam coating of the example. A foamed elastic sealing material was obtained by the same operation as in the example. The characteristics of each of the sealing materials of the above Examples and Comparative Examples were evaluated and were as shown in the following table.

【table】

[Table] As is clear from the above table, it can be seen that the foamed elastic sealing material of the present invention has suitable characteristics as a sealing material.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining an example of manufacturing the foamed elastic sealing material of the present invention, and FIG. 2 is a sectional view showing the shape and dimensions of an apparatus used to examine the watertightness of the foamed elastic sealing material. . DESCRIPTION OF SYMBOLS 1... Continuous foam, 2... Liquid material containing a heat-sensitive foaming agent and adhesive film forming substance, 3... Liquid material storage tank, 6... Heating drying chamber, 7... Foamed elastic sealing material.

Claims (1)

[Claims] 1. After impregnating an open foam with a liquid containing a heat-sensitive foaming agent and an adhesive film-forming substance, the foaming agent is dried while being gasified and foamed by heating, and the pore walls of the foam are A method for producing a foamed elastic sealing material, the method comprising forming an adhesive foamed film on.