JPH05131592A - Damping material - Google Patents

Abstract

PURPOSE:To provide a lightweight damping material having a thin constrained layer and a low-density adhesive viscoelastic layer. CONSTITUTION:In a damping material provided with a rigid base plate 2 and a viscoelastic substance layer 1 formed adhesively on the surface of the base plate, the viscoelastic substance layer contains a hollow filling agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping material which is directly attached and used for vibration damping of vehicles such as automobiles, home electric appliances and OA equipment.

[0002]

2. Description of the Related Art A damping material is a material that utilizes the characteristics of a viscoelastic substance to damp the vibration of a vibrating body to reduce noise generation. It can be roughly divided.

That is, the first one is a single-layer type damping material for damping the vibration of a vibrating body by utilizing the internal heat generated by the expansion and deformation of the viscoelastic substance, and the second one is a viscoelastic substance having a relatively high elastic modulus. It is a laminated type damping material which similarly performs vibration damping by causing shear deformation by sandwiching with a constraining layer having.

As the first single-layer damping material, a heat-fusion asphalt sheet widely used as a damping material for vehicle body panels of automobiles is well known. This is because the sheet thickness is made considerably thicker (3 to 10 mm) than the laminated damping material, or the high-density filler is kneaded in the viscoelastic material, in addition to the internal heat loss of the viscoelastic material. Then, the damping process is performed by adding the weight (equivalent mass) of the entire damping material.

The second constraining type vibration damping material may be a viscoelastic material, for example, an alkyl group having 4 to 10 carbon atoms.
Alkyl acrylate, lower alkyl acrylate,
Acrylate-based adhesive composition obtained by copolymerizing vinyl acetate or the like, or natural rubber, styrene-butadiene rubber,
An unvulcanized rubber composition obtained by mixing a tackifier, a rubber softening agent, a filler, etc. with one or more kinds of butyl rubber, reclaimed vulcanized reclaimed rubber, etc., which functions as a constraining layer It is configured such that a metal sheet such as aluminum is coated or laminated to a thickness of 0.1 to 3 mm and adhered to a vibration body to be subjected to a vibration damping treatment.

[0006]

In the case of the above-mentioned first single-layer type damping material, the damping material layer must be made considerably thick (3 to 10 mm) in order to obtain sufficient damping properties. As a result, the weight becomes large, and the use thereof is limited when the weight reduction of an automobile or the like is desired.

On the other hand, the second constraining type damping material is thinner than the first single layer type damping material and is expected to obtain high vibration damping performance. In order to obtain the performance of, the thickness of the constraining layer should be made considerably thick (about the same as the vibrating body), or the viscoelastic layer should be thicker, and the constraining type damping material should be a single layer type damping material. It is necessary to combine the functions of and are used in that way in reality. Therefore, as a result of this, in any case, the weight becomes large, and when the weight reduction is required, its use is limited.

It is an object of the present invention to provide a constraining layer damping material having a viscoelastic layer having an adhesive property, which is a lightweight damping material in which the constraining layer is thin and the viscoelastic layer has a low density. To do.

[0009]

In order to achieve the above object, the damping material of the present invention is a damping material comprising a rigid substrate and a viscoelastic material layer formed in close contact with the surface of the substrate. A hollow filler is contained in the viscoelastic material layer.

The rigid substrate used in the present invention includes:
It is not particularly limited as long as it holds and restrains the viscoelastic substance layer described later in a wide temperature range, but specifically, for example, aluminum, a metal foil such as stainless steel or an inorganic fiber cloth such as glass cloth is used. Can be mentioned.

The thickness of this rigid substrate is 10 to 300.
μm, especially 30 to 200 μm is desirable. If this thickness is less than 10 μm, the effect as a constraining layer is low. On the other hand, if it exceeds 300 μm, it is meaningless, and since the thickness is too thick, it lacks flexibility as a damping material and has poor workability for sticking to curved surfaces. It is not preferable because it lowers or increases the weight.

Examples of the viscoelastic material layer used in the present invention include those formed with the same adhesive as that used conventionally.

That is, as a specific example of this adhesive, for example, an acrylate-based adhesive composition obtained by copolymerizing an alkyl acrylate having an alkyl group with 4 to 10 carbon atoms, a lower alkyl acrylate, vinyl acetate, or the like, or An unvulcanized rubber composition obtained by compounding one or more kinds of natural rubber, styrene-butadiene rubber, butyl rubber, re-vulcanized reclaimed rubber, etc. with a tackifier, a rubber softening agent, a filler, etc. Can be mentioned.

The thickness of this viscoelastic material layer is 0.05 to 4
mm, particularly 0.1 to 3 mm is desirable, and if this thickness is less than 0.05 mm, desired adhesive force and damping characteristics cannot be obtained, while if it exceeds 4 mm, the effect of increasing the thickness is Not only does it reach the limit and is meaningless, but it also increases weight, which is not desirable.

The viscoelastic material layer used in the present invention is
In order to achieve overall weight reduction, its density is 0.3-
It is adjusted to 1.0 g / cm ³ .

The density of this viscoelastic material layer is 0.3 g / c.
If it is less than m ³ , the vibration damping property is low and the desired vibration damping effect cannot be obtained. On the other hand, if it exceeds 1.0 g / cm ³ , it becomes difficult to realize the desired weight reduction, which is not preferable.

As described above, in order to realize the weight reduction of the viscoelastic substance layer, the present invention is most characterized in that the viscoelastic substance layer contains the hollow filler.

The hollow filler may be an inorganic or organic hollow body, and a specific representative example thereof is a hollow glass bead having a density of 0.02 to 0.7 g / cm ³ or a shirasu. A hollow foam such as a balloon or a vinylidene chloride-based material can be used. The size of the hollow filler is preferably 2 to 200 μm, and particularly preferably 10 to 100 μm.

When the size of the hollow filler is less than 2 μm, it is difficult to obtain a hollow filler having a low specific gravity. On the other hand, 20
If it exceeds 0 μm, it becomes difficult to uniformly disperse it in the viscoelastic substance, and it easily breaks during the dispersion work, and it becomes impossible to achieve a desired low specific gravity.

[0020]

The damping material of the present invention has the above-mentioned constitution, and in particular, the hollow filler is contained in the viscoelastic substance layer formed in close contact with the rigid substrate surface, so that the overall weight reduction is realized. it can.

Further, it has the effect of converting the energy generated when the substrate vibrates into friction energy at the interface between the outer surface of the hollow filler and the viscoelastic substance to reduce the vibration.

In addition to that, the hollow filler slightly deforms when the substrate vibrates to absorb vibration energy, thereby exhibiting an extremely excellent vibration damping action.

[0023]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto. As shown in FIG. 1, a butyl rubber-based viscoelastic substance layer (1) having a thickness of 2 mm and having a composition of 100 μm
A vibration damping material of the present invention was obtained, which was composed of a laminate closely adhered to the aluminum sheet (rigid substrate) (2).

This damping material was placed and adhered on a steel plate having a thickness of 1.2 mm to obtain a test piece for evaluating damping characteristics.

Composition of viscoelastic material layer Butyl rubber 100 parts by weight Polybutene 80 parts by weight Petroleum resin 40 parts by weight SRF carbon 50 parts by weight Shirasu balloon 100 parts by weight

The above components were sufficiently kneaded with a pressure kneader and then formed into a sheet by a conventional method. * The density of this sheet was 0.41 g / cm ³ .

Comparative Example In the example, except that a hollow filler was contained in the viscoelastic substance layer, a so-called conventional type viscoelastic substance layer having the following composition using calcium carbonate was used. What was formed similarly to an Example was used. Therefore, the material and thickness of the rigid substrate, the thickness of the viscoelastic material layer, the kneading method, etc. were all the same as in the example.

Composition of viscoelastic material layer for comparative example Butyl rubber 100 parts by weight Polybutene 80 parts by weight Petroleum resin 40 parts by weight SRF carbon 50 parts by weight Calcium carbonate 100 parts by weight * Density as sheet 1.22 g / cm ³

Test Method (Damping Characteristics) Using the test pieces for evaluation in which the damping materials of Examples and Comparative Examples were attached to steel plates, the vibration damping performance of both test pieces was measured by the impulse vibration method. Loss factor η calculated from the measurement results
Fig. 2 shows the results obtained by determining the vibration damping effect with.

From the results shown in FIG. 2, it can be seen that the example shows better vibration damping characteristics at higher frequencies than the comparative example.

[0031]

In the damping material of the present invention, the density of the viscoelastic material layer used is remarkably lower than that of the conventional material, so that the damping material can be reduced in weight and can be filled. Since a hollow filler is used as the agent, an extremely excellent vibration damping effect can be obtained, especially in the high frequency region, as compared with the conventional one.

[0032]

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing damping characteristics of the example and the comparative example.

[0033]

[Explanation of symbols]

 1 Viscoelastic material layer 2 Rigid substrate

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukio Nishiyama 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (2)

[Claims] 1. A vibration damping material comprising a rigid substrate and a viscoelastic substance layer formed in close contact with the substrate surface, wherein a hollow filler is contained in the viscoelastic substance layer. Damping material. 2. The vibration damping material according to claim 1, wherein the hollow filler is an inorganic or organic hollow body.