JPH0564092B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a heat-resilient sheet suitable for filling and inserting as a soundproofing material or a heat insulating material into the voids of, for example, the body of an automobile or a building material panel. Regarding the manufacturing method.

[Conventional technology]

In an automobile body or building material panel, for example, as shown in Fig. 3, the outer shell is assembled with two steel plates 1a and 1b such as steel plates or stainless steel plates, and the inner cavity is filled with polyurethane foam, felt, glass fiber, etc. A sound insulating material 2 made of a sheet is inserted to improve sound absorption and insulation properties, and further improve heat insulation properties.

[Problem to be solved by the invention] By the way, recently, weight reduction has been particularly important in automobile bodies, so the gap between the steel materials 1a and 1b into which the soundproofing material 2 is to be charged is narrowed to about a few mm. I'm getting used to it. As a result, it becomes difficult to fill and install the soundproofing material 2 into such a narrow gap, resulting in problems such as decreased workability and productivity.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a method for producing a heat-recoverable sheet that has special properties that allow it to be easily filled into narrow voids.

[Means for solving problems]

The method for producing a heat-resilient sheet according to the present invention involves impregnating a flexible polyurethane foam sheet with a mixture of 100 parts by weight of asphalt emulsion and 5 to 55 parts by weight of thermoplastic resin emulsion, followed by drying. It is characterized by being compressed at a temperature of 30°C or less and maintaining the compressed state.

The asphalt emulsion used in the present invention may be one obtained by a known emulsion technique, 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 the distillation of asphalt-based crude oil, or blown asphalt obtained by oxidative polymerization by introducing heated air into this asphalt. A lower degree is preferable.

As the thermoplastic resin emulsion in the present invention, EVA resin emulsion (ethylene/vinyl acetate copolymer resin emulsion), polyethylene resin emulsion, vinyl acetate resin emulsion, nylon resin emulsion, etc. can be used. In the present invention, a mixed emulsion obtained by adding and mixing this thermoplastic resin emulsion to the above-mentioned asphalt emulsion is impregnated into a soft polyurethane foam. Solid content of emulsion is 5~
The amount shall be within the range of 55 parts by weight. The reason for this limitation will be explained in the section on effects below. The preferred mixing amount of these thermoplastic resin emulsions is 7.0 to 30 parts by weight based on 100 parts by weight of the asphalt emulsion.

The amount of impregnation in the above mixed emulsion may be adjusted depending on the application, but it is generally in the range of 300 to 1500% by weight in terms of solid content of the mixed emulsion.

In the present invention, the compressibility of the flexible polyurethane foam impregnated with the mixed emulsion is approximately 50% to 90% of the original thickness.

[Effect]

In the present invention, when a soft urethane foam is impregnated with a mixed emulsion of an asphalt emulsion and a thermoplastic resin emulsion and dried, a urethane foam with asphalt and thermoplastic resin particles attached to the inner wall surface of the open cells of the urethane foam is formed. is obtained. This impregnated urethane foam has lost some of its elasticity and restoring power due to the asphalt and thermoplastic resin particles contained in the cells.

Therefore, as shown in FIG. 1A, when this impregnated urethane foam 10 is cold pressed in a press machine kept at a temperature of 30°C or less, the impregnated urethane foam 10 has partially lost its restoring force. Due to the caking properties of the asphalt and thermoplastic resin particles contained therein, it is fixed in a thinly compressed state as shown in Figure B.

The sheet 11 obtained by compressing as described above is
At normal temperatures, it loses the restorability characteristic of urethane foam, but when heated, it becomes a heat-recoverable sheet that has the property of restoring to its original thickness.

In this case, the asphalt and the thermoplastic resin act synergistically with each other to suppress the restorability of the urethane foam. Therefore, the solid content of the thermoplastic resin emulsion in the mixed emulsion is 5 parts by weight per 100 parts by weight of the asphalt solid content.
If the amount is less than part by weight, use relatively low temperature (40℃~60℃)
℃), it has good resilience and recovers during storage and transportation at high temperatures. On the other hand, if the amount is more than 55 parts by weight, the characteristics of the asphalt particles, such as sound absorption, sound insulation, and heat insulation, will be reduced. This is the reason why, in the present invention, the mixing ratio of the asphalt emulsion and the thermoplastic resin emulsion is limited as described above.

The above-mentioned heat-resilient sheet 11 manufactured according to the present invention not only has a small volume and is easy to transport, but also can be made of a steel plate or the like when applied to the body of an automobile as a heat insulating material or a sound insulating material. Even when the internal void of the outer shell is very narrow, it can be filled with extremely good workability.

That is, as shown in FIG. 2A, two steel materials 1a,
The above-mentioned heat-recoverable sheet 1 manufactured with a thickness thinner than the void is placed in the internal void of the outer shell assembled in step 1b.
Insert 1. This operation is much easier than the conventional case of inserting and filling a sheet that is approximately the same as or slightly thicker than the gap, and can improve workability. Thereafter, when the inserted heat-resilient sheet 11 is heated, the sheet 11 expands and fills the internal void of the outer shell, as shown in FIG. It will be constructed in the best possible condition. The heating temperature for this is
Considering the time for restoration, a temperature of about 100 to 150°C is sufficient.

In the case of an automobile body, painting and baking processes are performed after inserting and filling the soundproofing material, so the inserted heat-recoverable sheet 11 is sufficiently heated in these processes. Therefore, there is no need to take any special heating means when applying the heat-recoverable sheet produced according to the present invention.

〔Example〕

Examples of the present invention will be described below.

Asphalt emulsion and ethylene/vinyl acetate copolymer resin are applied to a soft polyurethane foam sheet with specific gravity 0.016 and open cells of 5 mm thickness.
The mixture was mixed at a ratio of 100:15 and impregnated by the dipping method. The amount of impregnation was adjusted using a roll to 800 parts by weight per 100 parts by weight of the urethane foam.

Next, after drying by heating, cold pressing was performed using a press kept at a temperature of 25° C. to a thickness of 2 mm. The obtained sheet maintained a thickness of 2 mm at room temperature.

On the other hand, when this sheet was left in an oven kept at 120°C, it recovered to approximately its original thickness (approximately 5 mm).

〔Effect of the invention〕

As detailed above, according to the present invention, remarkable effects can be obtained, such as the ability to manufacture a heat-recoverable sheet with special properties that allow it to be easily filled into narrow voids.

[Brief explanation of the drawing]

Figures 1A and B are cross-sectional views for explaining the method of manufacturing a heat-recoverable sheet according to the present invention, and Figures 2A and B are
FIG. 3 is an explanatory diagram showing a method of using the heat-recoverable sheet manufactured according to the present invention, and FIG. 3 is a sectional view showing a soundproofing material sheet conventionally applied to the body of an automobile. 1a, 1b... Steel plate, 10... Impregnated urethane foam, 11... Heat restorable sheet.

Claims (1)

[Claims] 1 After impregnating a flexible polyurethane foam sheet with a mixture of 100 parts by weight (solid content) of asphalt emulsion and 5 to 55 parts by weight (solid content) of thermoplastic resin emulsion, it is dried and further heated to 30°C or less. A method for producing a heat-resilient sheet, characterized in that the sheet is compressed at a temperature of .