JP5506314B2 - Damping composition, damping material and damping sheet - Google Patents

Description

  The present invention relates to a vibration damping composition, a vibration damping base material, and a vibration damping sheet.

Conventionally, a thin plate is used as a part of a part of a car or home appliance, and the vibration sound of the thin plate is generated when the car or home appliance is operated. Therefore, in order to prevent the generation of this vibration sound, it is known to improve the vibration damping property of the thin plate, for example, by sticking a vibration damping sheet having a resin layer to the thin plate.
In addition, a thin plate disposed in the vicinity of a motor of an automobile engine room or a home appliance is likely to be at a high temperature. Therefore, a damping sheet capable of exhibiting a damping effect even at a high temperature is desired.

  For example, in order to obtain good vibration damping characteristics at a high temperature of 40 ° C. or higher, a damping sheet made of a damping material for high temperature containing butyl rubber and C5 petroleum resin has been proposed (for example, see Patent Document 1). ).

JP-A-9-136998

However, in the vibration damping sheet described in Patent Document 1, an improvement in vibration damping properties at room temperature (about 20 ° C.) and high temperature (about 40 ° C.) is recognized.
However, in such a vibration damping sheet, an improvement in the vibration damping property at room temperature is recognized, while a further improvement in the vibration damping property at a high temperature is desired.
An object of the present invention is to provide a vibration damping composition, a vibration damping base material, and a vibration damping sheet that are further improved in vibration damping properties at high temperatures.

In order to achieve the above object, the vibration damping composition of the present invention contains a millable silicone rubber and is molded into a sheet having a thickness of 1.8 mm, and then a C-type hardness meter according to JIS K 7312. The hardness measured 10 seconds after the start of pressing is 60 or less.
In the vibration damping composition of the present invention, it is preferable that the millable silicone rubber is uncrosslinked.

In addition, the vibration damping composition of the present invention preferably further contains a filler.
In addition, the vibration damping composition of the present invention preferably further contains a tackifier.
The vibration damping base material of the present invention is characterized in that the vibration damping composition described above is formed into a sheet shape.
The vibration damping sheet of the present invention includes the above-described vibration damping base material and a constraining layer laminated on one surface of the vibration damping base material.

The vibration damping composition of the present invention is further improved in vibration damping properties at high temperatures.
Therefore, if the damping base material of the present invention obtained by molding the damping composition of the present invention into a sheet and the damping sheet including the same are attached to a thin plate, the thin plate can be sufficiently controlled even when used at high temperatures. Can shake.

An embodiment of the vibration damping sheet of the present invention is an explanatory view of a method for arranging a vibration damping sheet on a thin plate, and (a) is a step of preparing the vibration damping sheet and peeling the release paper, (B) shows the process of sticking a damping sheet to a thin plate.

The vibration damping composition of the present invention contains millable silicone rubber as a main component.
The millable silicone rubber contains a linear polymer having a degree of polymerization of 3000 to 10,000, and a known additive such as a silica-based reinforcing filler is added.
Examples of the linear polymer include dimethyl silicone, diphenyl silicone, copolymers thereof, and copolymers thereof with vinyl silicone. These linear polymers can be used alone or in combination of two or more.

Examples of the silica reinforcing filler include precipitated silica, fumed silica, colloidal silica, and the like.
The plasticity of such a millable silicone rubber is, for example, 140 to 630, preferably 150 to 430. The plasticity of the millable silicone rubber is calculated according to JIS K6249.

As such a millable silicone rubber, a commercially available product can be used. For example, silicone rubber KE951U (manufactured by Shin-Etsu Chemical Co., Ltd.), KE551U (manufactured by Shin-Etsu Chemical Co., Ltd.) or the like is used.
In the present invention, the millable silicone rubber is preferably used without crosslinking (vulcanizing) the above-described linear polymer, that is, uncrosslinked (unvulcanized). That is, the millable silicone rubber preferably contains an uncrosslinked (vulcanized) rubber that does not contain a crosslinking agent (vulcanizing agent) or a crosslinking agent (vulcanizing agent), but is heated (for example, 160 ° C. or higher). Used as uncrosslinked rubber that has not been crosslinked (vulcanized) by heating. More preferably, the millable silicone rubber is an uncrosslinked rubber that does not contain a crosslinking agent.

Moreover, the vibration damping composition contains a filler and / or a tackifier as necessary.
Fillers are blended to improve vibration damping and processability, and include, for example, calcium carbonate (for example, heavy calcium carbonate, light calcium carbonate, white glaze), talc, mica, clay, mica powder, bentonite (olga) Including silica), silica, alumina, aluminum silicate, titanium oxide, carbon black, acetylene black, metal powder (for example, aluminum powder, iron powder), resin powder (for example, acrylic resin powder, styrene resin powder, etc.) Bead), glass powder (powder), boron nitride powder and the like.

These fillers can be used alone or in combination.
As the filler, talc and carbon black are preferably used in combination.
Further, when the vibration damping composition is required to have vibration damping properties and thermal conductivity, the filler is preferably a heat conductive filler such as metal powder or boron nitride powder.
Further, when the vibration damping composition is required to have vibration damping properties and electrical conductivity, the filler is preferably an electrically conductive filler such as carbon black or acetylene black.

The blending ratio of the filler is, for example, 150 parts by weight or less with respect to 100 parts by weight of the millable silicone rubber, and is preferably 100 parts by weight or less from the viewpoints of reinforcement, weight (weight reduction), and economy.
The tackifier is blended to improve vibration damping and adhesion, and includes, for example, rosin resin, terpene resin (eg, terpene-aromatic liquid resin), coumarone indene resin (coumarone resin) ), Petroleum resins (for example, C5 petroleum resins, C9 petroleum resins, C5 / C9 petroleum resins, C5 / C6 petroleum resins, etc.), phenol resins and the like.

These tackifiers can be used alone or in combination of two or more. The blending ratio of the tackifier is, for example, 100 parts by weight or less with respect to 100 parts by weight of the millable silicone rubber, and preferably 50 parts by weight or less from the viewpoints of solubility and adhesion (adhesion).
In addition to the above components, the vibration damping composition includes, for example, a thixotropic agent (for example, montmorillonite), a lubricant (for example, stearic acid), a pigment, a scorch inhibitor, a stabilizer, as necessary. Known additives such as softeners, plasticizers, antioxidants, antioxidants, UV absorbers, colorants, fungicides, flame retardants, and crosslinking agents such as peroxides in appropriate proportions It can also be contained.

And in order to prepare a damping composition, each above-mentioned component is mix | blended with the above-mentioned mixing | blending ratio, and these are mixed uniformly. The vibration damping composition can be prepared by kneading the above-described components with, for example, a mixing roll, a pressure kneader, an extruder, or the like.
The kneading conditions for each component are such that the temperature is lower than the vulcanization (crosslinking) temperature of the millable silicone rubber, and specifically, for example, 50 to 150 ° C, preferably 80 to 130 ° C.

Then, the obtained vibration damping composition (kneaded material) is formed into a sheet shape by a molding method such as calendar molding, extrusion molding or press molding.
The molding conditions of the sheet are that the temperature is lower than the vulcanization (crosslinking) temperature of the millable silicone rubber, and specifically, for example, 50 to 150 ° C, preferably 80 to 130 ° C.
Thereby, the sheet-like damping base material which consists of a damping composition can be obtained.

The thickness of the damping substrate is, for example, 0.2 to 3.0 mm, preferably 0.5 to 2.5 mm.
And, when the vibration damping base material has a thickness of 1.8 mm, a C-type hardness meter is used, and the hardness after 10 seconds after pressing the pressing needle against the sheet with a force of 10 N is 60 or less, preferably 50 or less, more preferably 40 or less, for example, 5 or more, preferably 10 or more.

When the hardness exceeds the above-mentioned range, the vibration damping performance is lowered and the vibration damping action cannot be expressed.
On the other hand, when the hardness is less than the above-described range, the vibration damping base material is likely to be deformed, and the handleability may be lowered.
The hardness of JIS K 7312 is calculated as the hardness 10 seconds after the pressing needle is pressed against the surface of the vibration damping substrate with a pressing force of 10 N using a C-type hardness meter.

Next, a vibration damping sheet provided with the above-described vibration damping substrate will be described.
The vibration damping sheet includes the above-described vibration damping base material and a constraining layer laminated on one side of the vibration damping base material.
The constraining layer constrains the damping base material to retain its shape, and imparts toughness to the damping base material to improve the strength. Further, the constraining layer has a sheet shape, is lightweight and thin, and is formed from a material that can be tightly integrated with the damping base material. Examples of such materials include glass cloth, metal foil, synthetic resin nonwoven fabric, and carbon fiber.

  The glass cloth is made of glass fiber and includes a known glass cloth. The glass cloth includes a resin-impregnated glass cloth. The resin-impregnated glass cloth is obtained by impregnating the above-described glass cloth with a synthetic resin such as a thermosetting resin or a thermoplastic resin, and includes known ones. In addition, as a thermosetting resin, an epoxy resin, a urethane resin, a melamine resin, a phenol resin etc. are mentioned, for example. Examples of the thermoplastic resin include vinyl acetate resin, ethylene / vinyl acetate copolymer (EVA), vinyl chloride resin, EVA / vinyl chloride resin copolymer, and the like. The above-mentioned thermosetting resin and thermoplastic resin can be used alone or in combination, respectively, and thermosetting resin and thermoplastic resin (for example, melamine resin and vinyl acetate resin) are mixed. You can also.

Examples of the metal foil include known metal foils such as an aluminum foil and a steel foil.
Of these constrained layers, glass cloth is preferably used in consideration of weight, adhesion, strength, and cost.
Moreover, the thickness of a constrained layer is 50 micrometers-2 mm, for example. In particular, when glass cloth is used as the constraining layer, the thickness is preferably 300 μm or less, and when a metal foil is used as the constraining layer, the thickness is preferably 100 μm or less from the viewpoint of handling. It is.

And a damping sheet can be obtained by bonding together the above-mentioned damping base material and a constraining layer. The total thickness of the vibration damping substrate and the constraining layer is, for example, 0.3 to 5 mm, and preferably 0.6 to 3.5 mm.
In addition, in the obtained damping sheet, a separator (until it is actually used on the surface of the damping base material (the surface on the opposite side to the back surface on which the constraining layer is attached), if necessary. Release paper) can also be attached.

The vibration damping sheet is used for damping a thin plate.
The thin plate is not particularly limited as long as vibration is required, and examples include thin plates used for various industrial products. The material for forming such a thin plate is not particularly limited, and is, for example, a metal (for example, aluminum or iron) or a resin (including FRP or synthetic resin). Specific examples of such thin plates include steel plates and outer plates of automobiles. In addition, examples of the thin plate include steel plates such as electric appliances and home appliances, and more specifically, steel plates inside a casing of a computer, a computer display, a television, a game device, a refrigerator, and a vacuum cleaner.

FIG. 1 is an explanatory view of a vibration damping base material and a method of using the vibration damping sheet for damping the vibration damping sheet of the present invention by sticking it to a thin plate.
Next, with reference to FIG. 1, the vibration damping base material and a method of using the vibration damping sheet, in which the vibration damping sheet is pasted on a thin plate, will be described.
First, in this method, a vibration damping sheet 1 is prepared as shown in FIG.

As described above, the damping sheet 1 has the damping base material 2 and the constraining layer 3 bonded together, and the surface of the damping base material 2 (the surface opposite to the back surface to which the constraining layer 3 is stuck). ), Release paper 6 is attached if necessary.
Next, in this method, the damping sheet 1 is disposed on the thin plate 5 as shown in FIG.
The thin plate 5 is used for the various industrial products described above, and includes, for example, an outer surface that appears in appearance and an inner surface that faces inward and does not appear in appearance.

In order to arrange the damping sheet 1 on the thin plate 5, as shown by the phantom line in FIG. 1A, first, the release paper 6 is peeled off from the surface of the damping substrate 2, and then, FIG. As shown in FIG. 2, the surface of the damping base material 2 is adhered to the inner surface of the thin plate 5.
In sticking the damping base material 2 to the thin plate 5, thermocompression bonding (hot pressing) can be performed as necessary.

The heating temperature in the thermocompression bonding is, for example, lower than the vulcanization (crosslinking) temperature of the millable silicone rubber, specifically 50 to 150 ° C., preferably 80 to 130 ° C., and the pressure is, for example, 0 15 to 10 MPa.
And by sticking the above-mentioned damping sheet 1 to the thin plate 5, even if the thin plate 5 is used under high temperature, it can fully dampen.

That is, the damping property of the thin plate 5 in a temperature range of 30 to 130 ° C., preferably 40 to 100 ° C., can be improved.
Specifically, the loss coefficient measured in the evaluation of Examples described later is 40 to 100 ° C., for example, 0.040 or more, preferably 0.050 or more, and usually 0.500 or less.

  In the above description, the damping base material 2 is bonded to the constraining layer 3 to form the damping sheet 1. For example, as shown by the phantom lines in FIG. When the gap between the outer surface of the thin plate 5 and the inner surface of the housing 7 is narrow (gap), the damping base material 2 is not prepared without preparing the constraining layer 3. Alternatively, it can be inserted into the gap between the outer surface of the thin plate 5 and the inner surface of the housing 7 and interposed between the thin plate 5 and the housing 7.

  In this case, the housing 7 is provided as a constraining layer, and the material thereof is preferably a metal such as aluminum or steel, preferably FRP.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the examples and comparative examples.
Example 1
100 g of millable silicone rubber (trade name “silicone rubber KE951U”, plasticity 240, manufactured by Shin-Etsu Chemical Co., Ltd.) is mixed with 20 g of talc, 5 g of carbon black and 10 g of a tackifier (petroleum resin), and these are 120 ° C. A vibration damping composition was prepared by kneading with a mixing roll.

Next, the vibration damping composition was press-molded at 80 ° C. and formed into a sheet having a thickness of 1.8 mm, thereby producing a vibration damping substrate.
Then, the vibration damping sheet | seat was obtained by bonding the produced damping base material and the 0.2-mm-thick glass cloth together.
Example 2
Except that the tackifier was not blended, each component was kneaded in the same manner as in Example 1 to prepare a vibration damping composition, then a vibration damping substrate was prepared, and then a vibration damping sheet was prepared. Obtained.

Example 3
Except that talc and carbon black were not blended, each component was kneaded in the same manner as in Example 1 to prepare a vibration damping composition, and then a vibration damping base material was prepared. Got.
Example 4
Except that talc, carbon black and tackifier were not blended, each component was kneaded in the same manner as in Example 1 to prepare a vibration damping composition, and then a vibration damping substrate was prepared. , Got a damping sheet.

Comparative Example 1
Each component was kneaded in the same manner as in Example 1 except that 2 g of the peroxide crosslinking agent was further added to the prepared vibration damping composition, and then a vibration damping base material was produced. A vibration sheet was obtained.
That is, in the same manner as in Example 1, by blending 100 g of millable silicone rubber with 20 g of talc, 5 g of carbon black and 10 g of a tackifier (petroleum resin) and kneading them by mixing at 120 ° C., A vibration damping composition was prepared, and then the vibration damping composition was cooled to 60 ° C., and peroxide-based crosslinking agent (2,5-dimethyl-2,5-bis (tertiary butyl peroxy) hexane was added in 80 2% hexane was added.

Next, the vibration damping composition was press-molded at 80 ° C. and formed into a sheet having a thickness of 1.8 mm, thereby producing a vibration damping substrate.
Thereafter, the produced vibration damping base material and a 0.2 mm thick glass cloth were bonded together, and then the vibration damping base material was vulcanized by heating to 165 ° C. to obtain a vibration damping sheet.
Table 1 shows the amount of each component of the vibration damping composition in each example and comparative example.

(Evaluation)
(1) Hardness By obtaining the value after 10 seconds using a C-type hardness meter in accordance with the test method of JIS K 7312 for the damping base materials (thickness 1.8 mm) of each Example and Comparative Example. The hardness was calculated. The results are shown in Table 1.
(2) Vibration control (loss factor)
By cutting out the vibration damping sheets obtained in each Example and Comparative Example to a size of 10 × 250 mm, and sticking this to one side of a cold-rolled steel plate having a size of 0.8 × 10 × 250 mm A test piece was obtained.

  Thereafter, the loss factor of the secondary resonance point at each temperature of 40 ° C., 60 ° C., 80 ° C., and 100 ° C. was measured by the central excitation method. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Damping sheet 2 Damping base material 3 Constrained layer 7 Case

Claims (5)

Containing millable silicone rubber uncrosslinked,
After being formed into a sheet having a thickness of 1.8 mm, the hardness after 10 seconds from the start of pressing, measured using a C-type hardness meter in accordance with JIS K 7312, is 60 or less, Damping composition. The vibration-damping composition according to claim 1 , further comprising a filler. The vibration-damping composition according to claim 1 or 2 , further comprising a tackifier. A vibration damping substrate, wherein the vibration damping composition according to any one of claims 1 to 3 is formed into a sheet shape. A damping base material according to claim 4 ;
A vibration damping sheet comprising a constraining layer laminated on one side of the vibration damping base material.

Images