JPH0641775B2 - Vehicle vibration control structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vibration damping treatment method for, for example, the floor surface of an automobile, and more specifically, it is a lightweight, lightweight material capable of exhibiting a peak of significantly excellent vibration damping property under a temperature condition of around 40 ° C. Vibration suppression processing method.

Conventionally, a sheet-shaped material containing a bituminous material and an inorganic filler as main components was cut into an arbitrary shape and heat-bonded alone to a floor surface of an automobile for use. These bituminous sheet-shaped damping materials have different damping effects depending on the temperature conditions due to the temperature sensitivity of bituminous materials, and when a normal 2 mm thick material is heat-sealed and applied, it will be around room temperature. It has the characteristic that the peak of the vibration damping property appears, and that the vibration damping property decreases temporarily at temperatures below and above it. Further, the temperature at which the vibration damping property has a magnitude and a peak increases or decreases in proportion to the thickness of the bituminous sheet-shaped vibration damping material, and moves to the high-low temperature side. Therefore, in order to satisfy the requirement of the vibration damping property that doubles the conventional level of the vibration damping property at around 40 ° C., which has been increasing recently, the thickness of the vibration damping material is about 3 to 4 times, that is, 8 to
It was necessary to increase to about 10 m / m, and on the other hand, there was a contradiction that could not be resolved with the high demand for weight reduction, and it was not practically applicable.

On the other hand, as a proposal to apply the foamable material between the steel sheets, the heat-foamable sound insulation member is housed in the hollow portion formed by joining the steel sheet and the steel sheet at the entire circumference of the peripheral portion and at any other point to heat-foam. A method of manufacturing a soundproof wall of an automobile that fills the hollow portion has been proposed. (Japanese Patent Laid-Open No. 52-62815) However, in the proposal, steel plates are joined to each other at the entire circumference of the peripheral portion and at any other points, and the heat-foamable sound insulating member is made of foamed rubber, foamed resin or the like. The use of plate-like sheets is only recommended, and the damping method and the use of bituminous foam material and the expansion ratio without binding the vehicle body steel plate and the plate-like object which becomes the constraining layer to each other. Should not be selected, etc.

The inventors of the present invention have made the above-mentioned demands regarding the vibration damping processing method for automobiles,
That is, research has been continued in order to provide a lightweight vibration damping method that exhibits a peak of vibration damping that doubles that of conventional ones at around 40 ° C., and in particular to provide an inexpensive bituminous material for satisfying the above-mentioned demand.

As a result, surprisingly, a sheet-like material that is mainly composed of bituminous material and an inorganic filler and, if necessary, is mixed with a rubber component and / or a resin component, which has been used as a conventional unit, is foamed at a specific ratio. The intermediate damping layer and the intermediate layer do not have a Young's modulus of 5 × 10 ¹⁰ dyne / cm ² at around 20 ° C. and a body steel sheet, and a vibration damping treatment method of forming a Saint-Gerci structure satisfies the above-mentioned demands. It has been found.

Therefore, an object of the present invention is to provide a lightweight vibration damping method capable of revealing a peak of remarkably excellent vibration damping property under a temperature condition of around 40 ° C.

INDUSTRIAL APPLICABILITY The invention of the present application is based on a vibration damping method of a Sangertian structure consisting of a base material / intermediate layer / constraint layer, and is capable of manifesting a vibration damping effect due to a slipping action generated in the intermediate layer due to vibration. It is possible to realize a vibration damping effect which is several times better than that of the above-mentioned proposal of the prior application in which the peripheral portion is joined and the hollow portion is filled.

The bituminous material used in the present invention may be any asphalt, and may be one or a mixture of two or more of straight asphalt, bron asphalt, semibron asphalt and the like.

Generally, softening points of bituminous substances alone or mixed asphalt and mixtures thereof with rubber components and / or resin components are 65 to 115 ° C and penetration is 5 to 100. When the penetration is increased, the softening point of asphalt is lowered and there is a drawback that workability is poor.To eliminate such a problem, a rubber component and / or a resin component is blended to increase the softening point and workability is improved. It is preferable to improve.

As the rubber component to be mixed if necessary, natural rubber or synthetic rubber such as polybutadiene, styrene-butadiene rubber, butyl rubber, neoprene rubber, chloroprene rubber may be selectively used. Also, the use of recycled rubber is preferable in terms of cost.

As with the rubber composition, the resin component to be mixed as necessary is preferably one or more of petroleum resin, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

Examples of the inorganic filler used as the other main component of the intermediate layer according to the present invention include talc, clay, powders such as calcium carbonate, fibrous substances such as asbestos and slug wool, and mica, scaly substances such as mica. The inorganic filler may be used alone or as a mixture of two or more kinds.

The mixing ratio of the bituminous material and the inorganic filler is preferably 50 parts by weight to 250 parts by weight of the inorganic filler with respect to 100 parts by weight of the bituminous material. If it is less than 50 parts by weight, there is a problem that the peak of the anti-vibration effect moves too much to the low temperature side of 40 ° C or less, and if it exceeds 250 parts by weight, the bituminous material cannot serve as a binder, and the As a result, the viscoelasticity of the intermediate layer is lost and the vibration damping effect itself deteriorates.

The sheet-shaped molded product of the present invention is 1.2 to 2.5 times as large as the sheet-shaped molded product at the time of heat-foaming fusion of the plate-shaped product having the specified Young's modulus on the surface and the body surface of the other surface on the other side. The foaming is performed at a ratio of, and the temperature at which the peak of the vibration damping property is moved to around 40 ° C., and the vibration damping effect is further improved, and it is necessary to mix the foaming agent as an essential component. Is.

As the foaming agent, one having a decomposition temperature of 90 to 160 ° C. is preferable in view of the temperature of the baking furnace in the painting process of automobiles,
On the other hand, in the production of the sheet-shaped molded product, it is necessary to consider kneading with the bituminous material and the inorganic filler at a temperature not higher than the decomposition temperature of the foaming agent. Diazoaminobenzol, azoisobutylnitrile, benzolsulfohydrazide, carbamic acid azide and the like can be used, but preferably azodicarbonamide, P, P′-oxybenzolsulfohydrazide, benzylmonohydrazole, dinitrosopentamethylenetetramine and the like. is there.

It is effective to use urea or its derivative and a thermosetting resin as the foaming aid.

The foaming agent is used in a proportion 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 sheet-shaped molded product. When the expansion ratio is 1.2 or less, a satisfactory foam cannot be obtained, the temperature peak of the vibration damping effect cannot be shifted to around 40 ° C, and the temperature peak of the vibration damping effect remains around 60 ° C. If it exceeds the range, there is a problem that the temperature peak of the vibration damping effect shifts too much to a low temperature region of 40 ° C. or less.

Further, a water absorbing composition may be used instead of the foaming agent or together with the foaming agent. Mixing of the water absorbent composition,
Even if water is simply mixed in as a substance that emits volatilized gas by heating, it does not disperse and uniform foaming cannot be expected. Therefore, it is attempted to obtain a sufficiently dispersed state by sufficiently adsorbing water to the water absorbing composition. It is a thing.

In any case, according to the present invention, the foamed state after heat-sealing is 1.
It is essential to foam 2 to 2.5 times, and only when a foamed state in such a range can be achieved, a peak of extremely excellent vibration isolation is exhibited under a temperature condition of around 40 ° C. It is possible to obtain a sheet having excellent anti-vibration properties in the temperature range, and in order to obtain such an expansion ratio, the type of foaming agent,
The amount of foaming agent should be determined in consideration of temperature conditions and sheet thickness. To more clearly show the reason for limiting the numerical value of the foaming ratio of 1.2 to 2.5 times the thickness ratio, when the expansion ratio is less than 1.2, the sheet-shaped molded product has a sheet thickness of Since the thickness of such a sheet is not sufficiently thick, the temperature at which the vibration damping performance is most excellent is around room temperature with such a thickness of the sheet, and the excellent vibration damping performance can be revealed at around 40 ° C where the vibration damping performance is most required while the vehicle is running. Therefore, the vibration damping property cannot be improved.

On the contrary, when the expansion ratio exceeds 2.5, the sheet thickness of the sheet-shaped molded article exceeds the desired thickness due to such foaming, and therefore, at such a sheet thickness, the temperature at which the vibration damping performance is the most excellent. Is in a low temperature range, and excellent vibration damping performance cannot be realized at around 40 ° C. where the most vibration damping performance is required while the vehicle is running, and therefore vibration damping performance cannot be improved.

Therefore, it is necessary to adjust the thickness of the sheet-shaped molded product so that the temperature at which the vibration damping performance is the best is around 40 ° C. at which the vibration damping performance is most required while the vehicle is running. -2.5 times the expansion ratio.

As an additional note, due to excessive foaming as a secondary matter, the internal density of the sheet-shaped molded article decreases, and the strength against pressure decreases,
The application to the floor of an automobile becomes unfavorable, and the thickness ratio must be specified from this point as well.

The sheet-shaped molded product to be used in the vehicle vibration damping method according to the present invention can be manufactured in the same process as that of the conventional vibration damping sheet, if the mixing timing of the foaming agent is selected. For example, when the conventional process of mixing the bituminous material that has been heated and melted and the inorganic filler in a warm kneader, and extruding and then thickening the bituminous material alone is 18
Since the bituminous material and the filler are kneaded to some extent because they are heated and melted to about 0 ° C., the foaming agent should be mixed when the temperature of the kneaded material reaches 90 ° C. or less. At this time, the initial mixing and the mixing of the foaming agent into the initial mixture may be performed in different steps, and in the case of a horizontal narrow continuous mixer, the foaming agent may be mixed in the middle of the mixer.

The plate-like material used as the constraining layer of the present invention has a constraining layer like that of the present invention when the reason why the Young's modulus near 20 ° C. is limited to 5 × 10 ¹⁰ dyne / cm ² or more In the case of the vibration damping material, the vibration damping property is realized by converting the vibration energy as noise into the thermal energy by the displacement strain between the constraining layer and the damping layer which is the intermediate layer.
Therefore, as the physical properties of the constraining layer, it is necessary that the strain does not easily generate elongation strain with respect to external stress, that is, the physical properties have a large elastic modulus. In other words, it is necessary to have a Young's modulus above a certain level. It is mandatory.

The Young's modulus E is a constant of proportionality when a proportional relationship is established between the stress T and the strain ε in elongational deformation, and E = T /
The relationship of ε holds.

When the Young's modulus of the constraining layer is less than 5 × 10 ¹⁰ dyne / cm ² ,
For example, as an extreme example, when elastic rubber is used as the constraining layer, the constraining layer does not generate the necessary displacement strain between the constraining layer and the damping layer, which is the intermediate layer, against the stress of vibration, and The extension strain is generated following the damping layer of, and it does not exhibit the excellent damping performance as a multilayer damping material that utilizes shear strain.
There is a problem in that the vibration damping property fluctuates significantly with temperature changes (the vibration damping performance is not stable).

Therefore, as an indispensable structural requirement, the Young's modulus of the constraining layer near 20 ° C. is 5 × 10 ¹⁰ dyne / cm ² or more.

A vibration suppressor of a type in which a sheet-shaped molded product made of bituminous material, an inorganic filler and a foaming agent, and rubber components and resin components mixed as necessary is sandwiched between a plate-shaped object having a specific Young's modulus and a body steel plate. In order to form a material, a sheet-shaped molded body is laminated on the surface of a body steel plate of a vehicle or the like, and then a plate-like object which is a constraining layer is laminated, and then heat-softening fusion foaming is performed by baking,
It may be integrated, or a method in which a sheet-shaped molded product is previously stuck to a plate-shaped product is laminated on the surface of a body steel plate, and then heat-softening fusion-foaming is performed by baking to integrate them.

That is, for example, the body steel plate surface of an automobile and the plate-like material that is the constraining layer are laminated on the body steel plate surface through a sheet-shaped molded body having excellent adhesiveness without performing spot welding or seamless welding, and then baked. For example, it is essential that the heat-softening, fusion-bonding and foaming are integrated.

Upon heat-softening fusion integration, baking at 90 ° C. or higher for about 30 minutes is preferable, but the value is not particularly limited due to the difference in the thickness of the sheet-shaped molded product and the like.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. Naturally, the invention is not limited to the following examples.

Example 1 45 parts by weight of asphalt heated to about 180 ° C., 10 parts by weight of slag wool, 40 parts by weight of calcium carbonate and 5 parts by weight of SBR were kneaded in a horizontal fine continuous kneader, and the temperature of the kneaded product was 85 ° C. When the temperature dropped, 2 parts by weight of azodicarbonamide was added as a foaming agent, and the mixture was stirred and dispersed to obtain a sheet-shaped molded body having a thickness of 3 mm and which was Example 1.

The sheet-shaped compact is cut into a size of 20 × 180 mm,
0.8 × 20 × 200mm steel plate and 0.6 × 20 × 200
mm aluminum plate (Young's modulus: 7.1 × 10 ¹¹ dyne
/ cm ² ) and baked at 140 ° C. for 20 minutes. The sheet-shaped molded body was fused to a steel plate and an aluminum plate, and the sheet-shaped molded body was foamed to a thickness of about 4.5 mm.

Example 2 Except that the compounding amount of azodicarbonamide was 8 parts by weight,
A sheet-shaped molded body was molded and baked according to the same composition and method as in Example 1. The sheet-shaped compact is fused to a steel plate and an aluminum plate, and the sheet-shaped compact is about 7.2 mm.
Was foaming.

Comparative Example 1 A sheet-shaped compact was molded and baked by the same formulation and method as in Example 1, except that the amount of azodicarbonamide was 0.8 part by weight. The sheet-shaped compact was fused to a steel plate and an aluminum plate, and the sheet-shaped compact had a thickness of about 3.
It had foamed to a thickness of 3 mm.

Comparative Example 2 A sheet-shaped molded article was molded and baked by the same composition and method as in Example 1 except that the compounding amount of azodicarbonamide was 10 parts by weight. The sheet-shaped compact was fused to a steel plate and an aluminum plate, and the sheet-shaped compact had a thickness of about 8.
It had foamed to a thickness of 5 mm.

Example 3 Petroleum resin 1 in place of 5 parts by weight of SBR in the formulation of Example 1
A sheet-shaped molded product was molded and baked by the same composition and method as in Example 1 except that 0 part by weight was compounded.
The sheet-shaped molded body was fused to a steel plate and an aluminum plate, and the sheet-shaped molded body was foamed to about 4.2 mm.

Example 4 A sheet-shaped molded product was molded and baked by the same composition and method as in Example 1 except that 5 parts by weight of a petroleum resin was added in addition to the composition in Example 1. The sheet-shaped molded product was fused to a steel plate and an aluminum plate, and the sheet-shaped molded product was foamed to a thickness of about 4.2 mm.

Example 5 A sheet-shaped molded body was obtained by the same composition and method as in Example 1, and the sheet-shaped molded body was cut into a size of 20 × 180 mm, and 0.8 × 20 × 200 mm steel plate and 0.4 × 20x2
00 mm steel plate (Young's modulus: 2.1 × 10 ¹² dyne / cm ² )
C., and baked at 140.degree. C. for 20 minutes. The sheet-shaped molded product was fused to two upper and lower steel plates, and the sheet-shaped molded product was foamed to a thickness of about 4.5 mm.

Comparative Example 3 A sheet-shaped molded body was obtained by the same composition and method as in Example 1, and the sheet-shaped molded body was cut into a size of 20 × 180 mm, and 0.8 × 20 × 200 mm steel plate and 0.6 × 20x2
00 mm polypropylene foam sheet (Young's modulus: 1.
It was sandwiched with 5 × 10 ¹¹ dyne / cm ² ) and baked at 140 ° C. for 20 minutes. The sheet-shaped molded body was fused to a steel plate and a polypropylene foam thin plate, and the sheet-shaped molded body was foamed to a thickness of about 4.5 mm.

Comparative Example 4 A sheet-shaped molded body was obtained by the same composition and method as in Example 1, the sheet-shaped molded body was cut into a size of 20 × 180 mm, and a 0.8 × 20 × 200 mm steel plate and 0.6 × 20x2
00 mm thin elastic rubber plate (Young's modulus: 3.0 × 10 ⁸ dyne
/ cm ² ) and baked at 140 ° C. for 20 minutes. The sheet-shaped molded product was fused to a steel plate and an elastic rubber thin plate, and the sheet-shaped molded product was foamed to a thickness of about 4.5 mm.

Test content The areal density (Kg / m ² ) of the sheet-shaped molded products obtained from the examples and comparative examples was measured with a platform.

According to the resonance method (refer to page 438 of "Handbook for Noise Control" published by Japan Society for Acoustic Materials), 20 ℃, 40 ℃, 60 ℃,
The loss coefficient η at each temperature of 80 ° C. was obtained. It is said that the larger the value of η is, the higher the damping effect is, and if the value is 0.05 or more, the damping effect is obtained.

As described above, the vehicle damping structure according to the present invention has a temperature of 40 ° C.
It was revealed that the vibration control structure has a very excellent vibration control effect and does not conflict with the reduction of vehicle weight.

[Brief description of drawings]

FIG. 1 shows that the ratio of the initial thickness and the thickness after heating is changed by adjusting the amount of the foaming agent blended in the sheet-shaped molded product,
The thickness ratio is plotted along the horizontal axis, the Young's modulus of the laminated plate-like material is 7.1 × 10 ¹¹ dyne / cm ² , and the thickness of the substrate steel sheet is 0.8 m.
It is a graph when the loss coefficient η at m and 40 ° C. is plotted on the vertical axis. FIG. 2 shows that the Young's modulus of the plate-shaped material is changed by changing the material of the plate-shaped material to be laminated on the sheet-shaped molding, and the Young's modulus is plotted on the horizontal axis, and the thickness ratio of the sheet-shaped molding from the beginning is changed. It is a graph when the vertical axis is the loss factor η at 1.5 times, the thickness of the substrate steel sheet is 0.8 mm, and 40 ° C.

Claims (4)

[Claims] 1. A bituminous material and an inorganic filler as main components, additives are mixed and heated to 1.2 to the initial thickness.
One side of a sheet-like molded article containing a foaming agent so as to have a thickness of 2.5 times has Young's modulus of 5 × 1 at around 20 ° C.
A vibration damping structure for a vehicle, characterized in that a plate-like material having a rate of 0 ¹⁰ dyne / cm ² or more is integrated with the other surface of the steel plate surface of a vehicle floor by heat-foam fusion bonding. 2. The vibration control structure for a vehicle according to claim 1, wherein the additive is a rubber component. 3. The vehicle vibration damping structure according to claim 1, wherein the additive is a resin component. 4. The vehicle vibration damping structure according to claim 1, wherein the additives are a rubber component and a resin component.