JPH05220883A - Damping sheet - Google Patents

Abstract

PURPOSE:To provide a damping sheet capable of being bonded to a vibration object having a curved surface shape, capable of developing excellent damping characteristics especially after bonded to the vibration object without requiring heat treatment. CONSTITUTION:A damping sheet having self-adhesiveness has a three-layered structure consisting of a highly elastic restriction layer 3, an intermediate restriction layer 2 composed of a vulcanized rubber mixture compounded with a hot- melt adhesive and a reinforcing material and a low elastic self-adhesive layer 1 having self-adhesiveness to a vibration object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping sheet which is directly attached to a vehicle such as an automobile, a home electric appliance, an OA equipment or the like for vibration damping, and particularly to a product. The present invention relates to a vibration damping sheet improved so that its performance can be exhibited without the need for heat treatment after being attached to.

[0002]

2. Description of the Related Art For continuously vibrating objects such as automobiles, a so-called viscoelastic substance converts mechanical energy due to vibration into heat energy by internal heat generation and dissipates the energy to disperse the vibration of a panel or the like. Damping processing is performed to reduce the generation of noise by damping.
In addition to automobiles, railway vehicles, transportation equipment such as aircraft, hoppers, industrial equipment such as crushers, building materials, buildings such as bridges, OA
It is also widely used in equipment and home appliances.

In this way, utilizing the characteristics of viscoelastic materials,
A material that damps vibrations of the structure and reduces noise generation is called a vibration damping sheet.
It can be roughly divided into the following two types.

That is, the first is a single-layer type damping sheet for damping the vibration of the vibration-damped body by utilizing the internal heat generated by the expansion and contraction of the viscoelastic substance, and the second is the viscoelastic substance relatively. It is a laminated type vibration damping sheet which is similarly sandwiched between constraining layers having a high elastic modulus to cause shear deformation and thereby vibration damping.

As the above-mentioned first single-layer vibration damping sheet, a heat-fusion asphalt sheet widely used as a vibration damping material for automobile body panels is well known. this is,
It is a solid sheet that does not show any fluidity at room temperature, and it is left standing on the panel body to be subjected to vibration damping during the automobile manufacturing process, and the temperature applied when baking the thermosetting resin paint is used. The vibration damping process is performed by fusing onto the panel.

In the second laminated vibration damping sheet, a viscoelastic substance, for example, an alkyl group having 4 to 10 carbon atoms is used.
Alkyl acrylate, lower alkyl acrylate,
An acrylate-based adhesive composition obtained by copolymerizing lower alkyl methacrylate, vinyl acetate, etc., or a tackifier for one or more of natural rubber, styrene-butadiene rubber, butyl rubber, re-vulcanized recycled rubber, etc. An unvulcanized rubber composition obtained by blending a rubber softening agent, a filler, etc., and applying or laminating this to a metal thin plate such as aluminum which functions as a constraining layer to a thickness of 0.1 to 3 mm, There is a damping material that makes this adhere to the panel body to be subjected to damping treatment.

However, in the case of the above-mentioned first single-layer type vibration damping sheet, in order to obtain sufficient vibration damping characteristics, the vibration damping sheet layer has to be made quite thick to 3-5 mm, and as a result,
When the weight becomes large and the weight of automobiles is required to be reduced, its use is limited.

Moreover, this type of vibration damping sheet has a large temperature dependence in its vibration damping characteristics, and has sufficient vibration damping properties at around room temperature, but has almost no vibration damping properties at high temperatures of 40 ° C. or higher.

On the other hand, the second laminated type vibration damping sheet is thinner and has higher damping characteristics than the first single layer type vibration damping sheet, so that it can be made lighter in weight. Similar to the layered type vibration damping sheet, the vibration damping characteristics have a large temperature dependency, and at a high temperature of 40 ° C. or higher, the vibration damping characteristics hardly exist.

Therefore, recently, in a vibration-damping sheet having initial tackiness, the sheet has a three-layer structure comprising a high-elasticity restraint layer, a medium-elasticity restraint layer made of a thermosetting resin layer, and a low-elasticity tacky layer. It has been proposed that the
-297434).

[0011]

This is because it has high vibration damping and reinforcing properties in a wide temperature range.
Although it is extremely excellent, since a thermosetting resin is used as the intermediate elastic constraining layer that is the intermediate layer, this thermosetting resin has flexibility in the state before the heat treatment, but after the heat treatment, It becomes a highly elastic and highly rigid body.

Therefore, it is necessary to attach the vibrating body having a curved surface shape in a state before the heat treatment and perform the heat treatment together with the vibrating body. When is low, its use is limited. Also, thermosetting resins have a limited pot life,
Long-term storage cannot be performed in the state before heat treatment.

According to the present invention, in this type of laminated vibration damping sheet, it is possible to perform the work of sticking to a braking body having a curved shape, and in particular, after sticking to a vibrating body having a curved shape, An object of the present invention is to provide a vibration damping sheet that can exhibit excellent vibration damping characteristics without requiring heat treatment and is not affected by pot life.

[0014]

In order to achieve the above object, the vibration damping sheet of the present invention is a vibration damping sheet having an adhesive property, wherein the vibration damping sheet comprises a high elastic constraining layer, a hot melt adhesive and A three-layer structure comprising an intermediate constraining layer made of a vulcanized rubber mixture containing a reinforcing agent and a low-elasticity adhesive layer having adhesiveness to a braking body.

The high elastic constraining layer used in the present invention has a dynamic elastic modulus of 10 ¹¹ to 10 ¹² dyne / cm ² , and by selecting one having such a dynamic elastic modulus, it will be described later. It is desirable because the elastic constraining layer and the low elastic pressure-sensitive adhesive layer are constrained in a wide temperature range, and vibration damping due to shear deformation of the resin layer is efficiently generated.

Typical of those having such a dynamic elastic modulus are metal foils such as aluminum and stainless steel and inorganic fiber cloths such as glass cloth.

The high elastic constraining layer has a thickness of 1
It is preferably 0 to 300 μm, particularly 30 to 200 μm. If this thickness is less than 10 μm, the effect as a constraining layer is low, while if it exceeds 300 μm, the thickness is too thick, so that it lacks flexibility as a vibration damping sheet, and the workability of sticking to curved surfaces decreases, and the weight increases. Therefore, it is not preferable.

The medium elastic constraining layer has a hot melt adhesive function and a dynamic elastic modulus of 10 ⁸ to 10 10.
It is characterized by using a vulcanized rubber admixture of ¹⁰ dyne / cm ² .

Here, the means for achieving the hot-melt type adhesive function is not particularly limited,
Examples thereof include a method of kneading and blending a petroleum-based resin, an olefin-based elastomer, or the like into a vulcanized rubber mixture, or coating the surface of the vulcanized rubber mixture.

By the way, although natural rubber and various synthetic rubbers can be used as the base polymer of the vulcanized rubber mixture, the dynamic elastic modulus of the medium elastic constraining layer is 10 ⁸ to 10 10.
^In order to obtain ¹⁰ dyne / cm ² , a reinforcing filler such as carbon black, white carbon, glass fiber or glass beads is kneaded and blended.

Thus, the dynamic elastic modulus of the medium elastic constraining layer is set to 1
The reason for setting it to 0 ⁸ to 10 ¹⁰ dyne / cm ² is that if it deviates from this range, the vibration damping characteristics will deteriorate in a high temperature region of 40 ° C. or higher.

The thickness of this intermediate constraining layer is 0.1 to 2 mm.
When the thickness is less than 0.1 mm, the effect as an intermediate constraining layer is deteriorated, which is not preferable. On the other hand, when the thickness exceeds 2 mm, the effect due to the thickening is not recognized, which is uneconomical. In addition, the weight becomes large, which is not preferable.

Further, the low elastic pressure-sensitive adhesive layer is not particularly limited as long as it has a dynamic elastic modulus of 10 ⁵ to 10 ⁷ dyne / cm ² , but specific representative examples thereof are acrylic and unvulcanized. Examples thereof include those using a rubber-based or butyl rubber-based adhesive.

Here, the dynamic elastic modulus is 10 ⁵ dy
If it is less than ne / cm ² , the adhesive layer is too soft and the holding power for the adherend becomes too small, which is not preferable. On the other hand, if it exceeds 10 ⁷ dyne / cm ² , the vibration damping property at low temperature to around room temperature deteriorates. Therefore, it is not desirable.

The thickness of this low elastic pressure-sensitive adhesive layer is 0.05 to 2 m.
m, especially 0.1 to 1 mm, is preferable, and if this thickness is less than 0.05 mm, the vibration damping property deteriorates, while
If it exceeds 2 mm, not only is the effect of increasing the thickness almost reached the limit, which is meaningless, but it is uneconomical and increases the weight, which is not preferable.

By using the three-layer laminated structure having the above-mentioned three kinds of elastic moduli, it has a high loss coefficient in a wide temperature range of −20 to 80 ° C. and exhibits good vibration damping characteristics.

[0027]

The vibration-damping sheet of the present invention has the above-mentioned structure and is a three-layer laminated structure, whereby a conventional two-layer restraint type vibration-damping sheet comprising an asphalt-based or metal restraint layer and a viscoelastic layer is obtained. In comparison, the steel sheet, which is the adherend, can also have a reinforcing effect, and has the effect of becoming a useful vibration damping sheet having both characteristics of vibration damping and reinforcing.

Further, in this three-layer laminated vibration damping sheet, the medium elastic constraining layer has a hot melt type adhesive function and a dynamic elastic modulus of 10 ⁸ to 10 ¹⁰ dyne / c.
Since a vulcanized rubber admixture of m ² is used and such a medium elastic constraining layer is used, it is semipermanently flexible without being restricted by pot life unlike thermosetting resins. Can have. Further, this three-layer laminated structure makes it possible to obtain stable vibration damping characteristics in a wide temperature range, and at the same time, it is possible to carry out the work of sticking to a braking body having a curved shape, and in particular, it has a curved shape. After being attached to the vibrating body, excellent vibration damping characteristics can be exhibited without requiring heat treatment, and as a result, stability is improved.

[0029]

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 low-elasticity adhesive layer (1) having a thickness of 0.5 mm made of the composition (A) described below and a thickness of 0.8 mm made of the composition (B) described below. Vulcanization E
Medium elastic constraining layer (2) made of PDM rubber mixture and 0.1 mm
A vibration-damping sheet of the present invention having a three-layer laminated structure (thickness: 1.4 mm) of a high-elasticity constraining layer (3) made of an aluminum foil was obtained.

This vibration damping sheet was placed on a steel plate having a thickness of 0.8 mm and adhered without heating to obtain a test piece for evaluating vibration damping characteristics.

By the way, in each of the layers, the elastic modulus of each layer is determined by the butyl rubber adhesive layer (low elastic adhesive layer (1)).
Is 9 × 10 ⁶ dyne / cm ² , and the vulcanized EPDM rubber mixture (medium elastic constraining layer (2)) is 5 × 10 ⁹ dyne / cm 2.
^2. Aluminum foil (high elastic constraining layer (3)) is 2 × 10 ¹¹ d
It was yne / cm ² .

Composition (A) Butyl rubber 100 parts by weight Polybutene 110 parts by weight Petroleum resin 40 parts by weight Calcium carbonate 125 parts by weight Carbon black 2 parts by weight After the above components are sufficiently kneaded with a pressure kneader,
It was made into a sheet by a conventional method.

Composition (B) EPDM rubber 100 parts by weight Glass fiber 100 parts by weight Carbon black 70 parts by weight Zinc oxide 5 parts by weight Stearic acid 2 parts by weight Vulcanization accelerator A 1 part by weight Vulcanization accelerator B 0.5 parts by weight Part Sulfur 2 parts by weight Olefin-based elastomer 10 parts by weight

After sufficiently kneading the above components with a pressure type kneader, a sheet is formed with a calender roll and at the same time,
It was laminated with the above aluminum foil (high elastic constraining layer) (3), and then heated in an oven at 160 ° C. for 30 minutes to be vulcanized and adhered.

Next, on the surface of this aluminum foil (high elastic constraining layer) (3), on the medium elastic constraining layer (2) comprising the composition (B), a low elastic constraining layer (constituting the above composition (A) ( 1) was formed into a sheet by a conventional method, and laminated and adhered.

It was confirmed that this product exhibits excellent adhesiveness to an adherend such as a steel plate without heating.

Comparative Example The same procedure as in Example was used except that a medium elastic constraining layer made of the composition (C) shown below was used in place of the medium elastic constraining layer.

Composition (C) Liquid epoxy resin 100 parts by weight Dicyandiamide 5 parts by weight Imidazole 0.6 parts by weight Talc 100 parts by weight Carbon 1 part by weight

However, in the comparative example, since the thermosetting resin is used, after mounting and adhering on the steel plate, 17
Cured by heating in a 0 ° C. oven for 30 minutes.

Test Method (Vibration Damping Property) The vibration damping performance of each of the test pieces of Examples and Comparative Examples prepared by the above method was measured by the impulse vibration method. The damping effect is determined by the loss coefficient η calculated from the measurement result, and a plot is shown in FIG.

Bending Strength Test (Reinforcement Property) A support base having two vertical flat plates (width 50 mm) having an inverted U-shaped cross section with tips having a radius of curvature of 5 mm and arranged in parallel with a distance between the tips of 100 mm, A vertical flat plate (width 50 mm) that horizontally supports a test piece 70 mm in width and has a U-shaped cross section with a radius of curvature of 10 mm from the top in the center thereof.
Bending stress when a load is applied at (kg / 70mm
The width) was measured. The results are shown in Table 1.

[0042]

[Table 1]

From the results shown in FIG. 2, the example has a wider temperature range (-20 to 80) than the comparative example.
It is recognized that excellent vibration damping properties are exhibited at (° C).

Further, from the results shown in Table 1, it is recognized that the examples have good reinforcing effects and are sufficiently practical.

[0045]

Since the present invention is constructed as described above, it has the same damping characteristics as when the conventional type thermosetting resin is used, and it was necessary in the conventional type. No heat treatment is required after attaching the braking body, and there is no restriction on pot life.

As a result, the present invention can be applied even if the portion to be attached to the braking body has a curved shape, and can be used even if the braking body cannot be heat-treated. In addition, it has the effect that it can be stored for a long period of time in the state of the vibration damping material alone.

[0047]

[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.

[0048]

[Explanation of symbols]

 1 Low elastic adhesive layer 2 Medium elastic constraining layer 3 High elastic constraining layer

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

Claims (2)

[Claims] 1. A vibration-damping sheet having tackiness, wherein the vibration-damping sheet comprises a highly elastic constraining layer, an intermediate constraining layer made of a vulcanized rubber mixture containing a hot-melt adhesive and a reinforcing agent, and a damping body. A vibration-damping sheet, which is a three-layer structure including a low-elasticity adhesive layer having adhesiveness with respect to. 2. The elastic modulus of each of the high elastic constraining layer, the medium elastic constraining layer and the low elastic constraining layer is 10 ¹¹ to 10 ¹² dyn.
e / cm ² , 10 ⁸ to 10 ¹⁰ dyne / cm ² or 1
The vibration damping sheet according to claim 1, which has a viscosity of 0 ⁵ to 10 ⁷ dyne / cm ² .