JPH0214228B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vibration damping treatment method for, for example, the floor surface of an automobile, and more particularly to a lightweight vibration damping treatment method that can exhibit an extremely excellent peak of vibration damping performance under temperature conditions around 40°C. Conventionally, sheet materials containing bituminous materials and inorganic fillers as main components have been cut into arbitrary shapes and individually heat-sealed to the floor surfaces of automobiles. These bituminous sheet-shaped vibration damping materials have different damping effects depending on temperature conditions due to the temperature sensitivity of bituminous materials. It has the characteristic that a vibration damping property peak appears, and at temperatures below and above this peak, the damping property gradually decreases. Furthermore, the magnitude of the damping properties and the temperature at which the peak occurs increase or decrease and move toward higher and lower temperatures in proportion to the thickness of the bituminous sheet-like damping material. Therefore, in order to satisfy the recently increasing demand for damping performance that is twice the level of conventional damping performance at temperatures around 40℃, the thickness of the damping material must be increased by about 3 to 4 times, that is, 8 to 10 m. /m, and on the other hand, an irresolvable contradiction arose between this and the increasing demand for weight reduction, making it impossible to put it to practical use. In addition, there is a method in which the bituminous sheet vibration damping material is sandwiched between steel plates and the peak of vibration damping property is moved to the high temperature side.
Unless the adhesion area is 70% or more, excellent vibration damping properties may not be achieved. On the other hand, as a proposal to allocate a foamable material between steel plates, a heat-foamable sound insulating material is housed in a hollow space formed by joining the steel plates together at the entire periphery and at any other arbitrary point, and then heated and foamed. has proposed a method of manufacturing a soundproof wall for an automobile that fills the hollow space.
(Japanese Unexamined Patent Publication No. 52-62815) However, in this proposal, the steel plates are joined all around the periphery and at other arbitrary points, and the thermally foamable sound insulating member is made of foamed rubber, foamed resin, etc. The use of a plate-shaped sheet is only recommended, and a damping method that does not involve bonding the vehicle body steel plate and the plate-shaped material serving as the restraining layer to each other, the use of bituminous foam materials, and the foaming ratio There is no mention of whether one should choose the other. The present inventors have proposed a lightweight vibration damping method that can achieve a peak of damping performance that is double that of the conventional method at around 40°C, in particular, in order to satisfy the above-mentioned demands in a vibration damping treatment method for automobiles. Research has continued in order to provide the use of inexpensive bituminous materials. As a result, we unexpectedly found that a sheet-like material, which was conventionally used as a single material mainly composed of bituminous materials and inorganic fillers, was foamed at a specific ratio to form an intermediate layer, and a restraining layer made of steel plate etc. and a body steel plate. It has been discovered that a vibration damping treatment method using a sandwich structure structure advantageously satisfies the above requirements by completely adhering the vibration damping sheet to the surface of the restraining layer due to foaming. Therefore, it is an object of the present invention to provide a lightweight vibration damping method that allows complete adhesion between the damping sheet and the restraining layer surface, and furthermore allows a peak of extremely excellent damping performance to be achieved under temperature conditions around 40°C. It's about doing. Therefore, the gist of the present invention is that the mixing ratio is bituminous.
A vibration damping sheet made by mixing a foaming agent into a composition whose main components are a bituminous material and an inorganic filler, which is 50 to 250 parts of an inorganic filler per 100 parts by weight, is placed on a vehicle steel plate. A vibration damping treatment method for a vehicle, which comprises laminating a restraining layer and then heating the damping sheet to foam and fuse the vibration damping sheet to a foaming ratio of 1.1 to 2.5 times. It is in. The present invention reduces the adhesion area of the intermediate layer and the constraint layer to approximately
100%, and is based on the principle of vibration damping method of Sanderutsch structure consisting of base material/intermediate layer/restriction layer. It is possible to realize a vibration damping effect that is several times better than the proposal of the previous application in which the peripheral portions of the steel plates are joined and the hollow portion is filled. The bituminous material which is the main component of the vibration damping sheet of the present invention may be any asphalt, and may be one or a mixture of two or more of straight asphalt, blown asphalt, semi-brown asphalt, and the like. Generally, they are straight asphalt alone, blown asphalt alone, or a mixture of straight asphalt and blown asphalt. The inorganic fillers contained as other main components can be in the form of powders such as talc, clay, and calcium carbonate, in the form of fibers such as asbestos and slag wool, in the form of scales such as mica and mica, and in the form of hollow spheres such as silica balloons. It may be used alone or as a mixture of two or more of the inorganic fillers. In addition, when using organic fillers together, synthetic resin powder,
It is better to use synthetic resin fiber scraps, etc. The mixing ratio of the bituminous material and the inorganic filler is preferably 50 to 250 parts by weight of the inorganic filler to 100 parts by weight of the bituminous material. If it is less than 50 parts by weight, construction performance may be affected due to sagging during heat fusion. If the amount exceeds 250 parts by weight, the bituminous material will not be able to function as a binder, and will eventually lose its viscoelasticity as an intermediate layer.
There is a problem that it is difficult to adapt to areas with irregularities such as bead parts, and the damping performance itself deteriorates. In addition, it is preferable to mix a rubber component or a resin component with the vibration damping sheet component as necessary.As the rubber component, synthetic rubber such as natural rubber, polybutadiene, styrene-butadiene rubber, butyl rubber, neoprene rubber, or chloroprene rubber can be used. Good to use selectively. Further, the use of recycled rubber is preferable from the viewpoint of cost. As for the resin component to be mixed as needed like the rubber component, it is preferable to use one or more of petroleum resin, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer. The vibration damping sheet of the present invention is produced by foaming the vibration damping sheet at a magnification of 1.1 to 2.5 times during heating and foaming fusion of a restraining layer made of a steel plate or the like on the surface and the vehicle body surface on the other side. The sheet and the restraining layer are almost completely adhered to each other, and the temperature at which the vibration damping property peaks is shifted to around 40°C, and the vibration damping effect is improved. In addition, a foaming ratio of 1.2 to 1.5 times is most preferable for complete adhesion of the damping sheet and the restraining layer, but 1.1 to 2.5
If the range is twice that, these effects will be satisfactorily manifested. The blowing agent preferably has a decomposition temperature of 90 to 160°C, considering the temperature of the baking furnace used in the automobile painting process.On the other hand, when producing the sheet-like molded product, it is preferable to use a blowing agent whose decomposition temperature is below the decomposition temperature of the blowing agent. Consideration must be given to kneading with bituminous materials and inorganic fillers. Diazoaminobenzole, azoisobutylnitrile, benzol sulfohydrazide, carbamate azide, etc. can be used, but preferred are azodicarbonamide, P,P'-oxybenzole sulfohydrazide, benzyl monohydrazole, dinitrosopentamethylenetetramine, etc. . It is effective to use urea and its derivatives, thermosetting resins, etc. as foaming aids. The foaming agent is preferably used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the main component of the damping sheet. If the amount is less than 0.1 parts by weight, the foaming ratio is not more than 1.1. It is not possible to obtain a foam that
The temperature peak of the anti-vibration effect cannot be shifted to around 40℃,
The temperature peak of the anti-vibration effect remains around 60℃,
If the amount exceeds 10 parts by weight, the temperature peak of the vibration damping effect will be 40℃.
There is a problem in which the temperature shifts too far to the following low temperature range. Furthermore, the water-absorbing composition may be used as an alternative to or together with a foaming agent. The mixing of the water-absorbing composition is a material that releases volatile gas when heated, and even if water is simply mixed in, it will not be dispersed and uniform foaming cannot be expected. The aim is to obtain a distributed state. In any case, in the present invention, it is essential that the foamed state after heat fusion is 1.1 to 2.5 times the thickness of the vibration damping sheet compared to before heat fusion, and within this range. Only by achieving this state can we obtain a sheet that exhibits an extremely excellent vibration-proofing property peak under a temperature condition of around 40°C and has excellent vibration-damping properties over a wide temperature range. In order to obtain the foaming ratio, the amount of foaming agent should be determined by taking into consideration the type of foaming agent, temperature conditions, and sheet thickness. If the foaming ratio is less than 1.1, the peak of the vibration damping effect will shift to around 40℃ and no improvement in damping performance will be obtained, and if it exceeds 2.5, the peak of the vibration damping effect will shift to below 40℃. In addition to this, the compressive strength decreases, causing problems when applied to, for example, automobile floors. The sheet-like molded body used in the vehicle vibration damping method of the present invention can be manufactured in the same process as conventional vibration damping sheets by selecting the timing of mixing the foaming agent. For example, when using the conventional process of mixing heat-molten bituminous material and inorganic filler in a heating kneader, extruding, and then rolling, the bituminous material alone has been heated and melted at about 180°C, so the bituminous material is When the filler and filler have been kneaded to some extent and the temperature of the kneaded material has dropped to 90°C or less, the blowing agent should be mixed in. At this time, the initial mixing and the mixing of the blowing agent into the initial mixture may be separate processes, and in the case of a horizontally narrow continuous mixer, the blowing agent may be mixed in the middle of the mixer. As the plate-like material used as the constraining layer of the present invention, an aluminum plate, an FRP plate-like material, preferably a metal plate such as a steel plate, a mineral-based hard plate, a synthetic resin-based hard plate, etc. can be suitably used. In order to create a damping material of the type in which a damping sheet made of a bituminous material, an inorganic filler, a foaming agent, and rubber components and resin components mixed as necessary are sandwiched between the restraining layer and the body steel plate, A method is used in which a damping sheet is laminated on the steel plate surface of a body such as a vehicle, and then a plate-like object with a restraining layer is laminated, and then thermally softened and fused and foamed by baking to integrate. That is, for example, the surface of an automobile body steel plate and a plate-shaped object serving as a restraining layer are laminated on the body steel plate surface via a vibration damping sheet with excellent adhesiveness without performing spot welding or seamless welding, and then baking, etc. It is essential to integrate the materials by thermal softening, fusion, and foaming. For thermal softening and fusion integration, it is preferable to bake at 90°C or higher for about 30 minutes, but this value is not particularly limited due to differences in the thickness of the damping sheet. Examples are given below to explain embodiments of the present invention in more detail. Naturally, the present invention is not limited to the following examples. Example 1 45 parts by weight of asphalt heated and melted at about 180°C,
10 parts by weight of asbestos and 45 parts by weight of calcium carbonate were kneaded in a horizontal narrow continuous mixer, and when the temperature of the kneaded product fell to 85°C, 2 parts by weight of azodicarbonamide was added as a blowing agent and dispersed with stirring. ,3
A sheet-like molded body was made as an example with a thickness of m/m. The sheet-like molded body was cut into a size of 20×180 m/m, sandwiched between steel plates of 0.8×20×200 and 0.4×20×200 m/m, and baked at 140° C. for 20 minutes. The sheet-like molded body is fused to two steel plates,
The sheet-shaped molded product was foamed to a thickness of about 4.8 m/m. Example 2 45 parts by weight of asphalt heated and melted at about 180°C,
10 parts by weight of asbestos, 40 parts by weight of calcium carbonate and 5 parts by weight of SBR are kneaded in a horizontal narrow continuous mixer,
When the temperature of the kneaded product decreased to 85° C., 2 parts by weight of azodicarbonamide as a blowing agent was added, stirred and dispersed, and a sheet-like molded product of Example 2 having a thickness of 3 m/m was formed. The sheet-like molded body was cut into a size of 20 x 180 m/m, and a steel plate of 0.8 x 20 x 200 m/m and a 0.6 x 20 x
Clamped between 200m/m aluminum plates and heated at 140℃ for 20
I baked it for a minute. The sheet-like molded body is
It was fused to the steel plate and the aluminum plate, and the sheet-shaped molded product was foamed to a thickness of about 4.5 m/m. Example 3 35 parts by weight of asphalt heated and melted at about 180°C,
10 parts by weight of asbestos, 45 parts by weight of calcium carbonate, and 10 parts by weight of petroleum resin are kneaded in a horizontal narrow continuous mixer, and when the temperature of the kneaded material drops to 85°C, a gel-like mixture that has absorbed 500 times more water from the middle is formed. 20 parts by weight of vinyl alcohol/acrylic acid copolymer were added, stirred and dispersed to form a sheet-like molded product of Example 3 having a thickness of 3 m/m. The sheet-shaped molded body was cut into a size of 20 x 180 m/m, and a steel plate of 0.8 x 20 x 200 m/m and a 0.8 x 20 x
It was sandwiched between 200 m/m FRP plates and baked at 140°C for 20 minutes. The sheet-like molded body is made of a steel plate and
Fused to FRP board, the sheet-shaped molded body is approximately 4.9m/m
It was foaming thickly. Comparative Example 1 45 parts by weight of asphalt, 10 parts by weight asbestos, and 45 parts by weight of calcium carbonate were sequentially kneaded in a horizontal narrow continuous kneader, and after stirring and dispersion, a sheet-like molded product with a thickness of 3 m/m as a comparative example was obtained. did. The sheet-like molded body was cut into a size of 20 x 180 m/m, sandwiched between 0.8 x 20 x 200 and 0.4 x 20 x 200 m/m steel plates, and baked at 140°C for 20 minutes.
The sheet-like molded body was fused to two steel plates. Comparative Example 2 45 parts by weight of asphalt, 10 parts by weight of asbestos, and 45 parts by weight of calcium carbonate were kneaded in a horizontal narrow continuous kneader, and when the temperature of the kneaded product fell to 85°C, azodicarbonate was added as a blowing agent. 2 parts by weight of amide was added, stirred and dispersed to form a sheet-like molded product having a thickness of 3 m/m as a comparative example. The sheet-like molded body was cut into a size of 20 x 180 m/m, sandwiched between 0.8 x 20 x 200 and 0.4 x 20 x 200 m/m steel plates, and baked at 140°C for 20 minutes.
The sheet-like molded body is fused to two steel plates and has a thickness of approximately
It was foaming to a height of 8.4m. Comparative Example 3 45 parts by weight of asphalt, 10 parts by weight of asbestos, and 45 parts by weight of calcium carbonate were sequentially kneaded in a horizontal narrow continuous kneader, and after stirring and dispersion, a sheet-like molded product with a thickness of 9 m/m as a comparative example was obtained. did. The sheet-shaped molded body was cut into a size of 20 x 180 m/m, placed on a 0.8 x 20 x 200 steel plate, and heated at 140°C.
I baked it for 20 minutes. The sheet-like molded body was fused to a steel plate. Comparative Example 4 45 parts by weight of asphalt, 10 parts by weight of asbestos, and 45 parts by weight of calcium carbonate were sequentially kneaded in a horizontal narrow continuous mixer, and after stirring and dispersion, a sheet-like molded product with a thickness of 3 m/m as a comparative example was obtained. did. The sheet-shaped molded body was cut into a size of 20 x 180 m/m, placed on a 0.8 x 20 x 200 m/m steel plate,
Baking was performed at 140°C for 20 minutes. The sheet-like molded body was fused to a steel plate. Test details The areal densities (Kg/m ² ) of the sheet-like molded bodies obtained in Examples and Comparative Examples were measured using a stand. By the resonance method (see page 438 of "Noise Countermeasures Handbook" published by Japan Acoustic Materials Association), 20℃, 40℃,
The loss coefficient η at each temperature of 60°C and 80°C was determined. The larger the value of η, the higher the soundproofing effect, and it is said that if it is 0.05 or more, there is a vibrationproofing effect. Test results Example 1 13.7Kg/m ² (0.8t/3m/m sheet with a foaming ratio of 1.6x/0.4t) Example 2 13.9Kg/m ² (0.8t/3m/m sheet with a foaming ratio of 1.6x/0.6 t) Example 3 13.4Kg/m ² (0.8t/3m/m sheet with a foaming ratio of 1.7 times/0.8t) Comparative Example 1 13.7Kg/m ² (0.8t/3m sheet/
m/0.4t) Comparative Example 2 13.7Kg/ ^m2 (0.8t/3m/m sheet with a foaming ratio of 2.8x/0.4t) Comparative Example 3 19.6Kg/ ^m2 (0.8t/sheet 9m/
m) Comparative Example 4 10.6Kg/m ² (0.8t/sheet 3m/
m)

[Table] As described above, the sandwich structure obtained by the vehicle vibration damping method of the present invention exhibits a peak of extremely excellent vibration damping effect at 40°C, and does not interfere with vehicle mitigation. It was hot.

Claims (1)

[Claims] 1. A vibration damping sheet made by mixing a foaming agent into a composition whose main components are a bituminous material and an inorganic filler, with a mixing ratio of 50 to 250 parts by weight of an inorganic filler to 100 parts by weight of a bituminous material, A vibration damping treatment method for a vehicle, which comprises placing the damping sheet on a vehicle steel plate, laminating a restraining layer, and then heating the damping sheet to foam and fuse the damping sheet to a foaming ratio of 1.1 to 2.5 times.