JPH0156664B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field] The present invention relates to vibration damping steel plates for structural members (vibration noise sources) of vehicles, ships, machines, etc., and more specifically, structures that require oil resistance such as vehicle oil pans, cylinder head covers, and shielding plates. Related to damping steel plates for members. [Prior art] Conventionally, as a means of reducing vibrations and noise generated from various structural members such as those mentioned above, a sandwich structure is used to create a sandwich structure with a viscoelastic material as an intermediate layer between two steel plates, and to reduce vibrations and noise caused by steady vibrations or blows and impacts. A damping steel plate is known that is configured to absorb vibration energy and further convert it into thermal energy due to internal friction to reduce noise, that is, to exhibit a damping effect.Generally, the viscoelastic body is made of resin. were mainly used. The required properties of the vibration damping steel plate include low to high temperatures, e.g. 0°C to
It is preferable that the value of the loss coefficient η is large and kept constant over a wide temperature range such as 100° C., and it is considered that there is no problem in practice if η is 0.03 or more. [Problems to be solved] However, the damping steel plates for structural members that require oil resistance as described above require the use of a specific resin with excellent oil resistance as a viscoelastic body, which limits flexibility in design. Not only is the viscoelastic characteristic unique to the resin, i.e., η is limited by the glass transition temperature (Tg)
Because it has a sharp peak (maximum) near the
The temperature range in which the damping effect is exerted is narrow, and
The temperature dependence of η is large, and when two types of resins with different Tg are blended in an attempt to widen the temperature range in which the vibration damping effect is exerted, the compatibility between the resins is poor, resulting in poor mechanical strength. It becomes unusable. Furthermore, in general, the adhesive strength between resin and steel plate is not only low (about 1 to 2 kg/cm in T-peel strength), but strong in tension and compression but weak in bending and peeling. There is a serious practical problem in that flow occurs at high temperatures (above the flow temperature) and the steel plate slips off. Based on such circumstances, the present invention further provides acrylonitrile-butadiene copolymer rubber (hereinafter referred to as
NBR) has a Tg in the low temperature range (around -55 to -20℃), but η is broad over a wide temperature range, has little temperature dependence, and has excellent oil resistance. , η is dependent on the modulus of elasticity (Young's modulus), and it was invented as a result of intensive research based on the knowledge that increasing the modulus of elasticity increases the value of η. Structural members of machinery, more specifically vehicle oil pans, cylinder head covers, shielding plates, etc., are required to be oil resistant, and they exhibit excellent vibration damping effects in a wide temperature range from 0°C to 100°C, as well as at high temperatures. It is an object of the present invention to provide a vibration-damping steel plate with excellent durability, which prevents the steel plate from slipping down when the steel plate is moved. [Solution Means] In order to achieve the above object, in the present invention, a vibration-damping steel plate is formed by sandwiching a viscoelastic body made of NBR mixed with a non-thermosetting phenolic resin between two steel plates. It was constructed. NBR is the amount of acrylonitrile (hereinafter referred to as ACN)
There is no particular limitation on the amount (described as "amount"), but in consideration of oil resistance, an amount of about 30 to 50% by weight is used. The peak temperature of η of such NBR is approximately -
It exists around 25°C to 0°C. As the non-thermosetting phenolic resin, 10 to 90 parts by weight of a novolac type phenol resin such as pure phenol, alkyl-modified phenol, cashew-modified phenol, terpene-modified phenol, etc. is blended with 100 parts by weight of NBR. In the present invention, the non-thermosetting phenolic resin was selected as the resin to be blended with NBR.
In addition to the fact that phenolic resin itself has good compatibility with NBR, when thermosetting phenolic resin (resol type phenolic resin) is used, curing is accelerated by heating and the viscoelastic body becomes too hard, making it difficult to achieve the desired control. While the vibration effect cannot be obtained, by blending the non-thermosetting phenolic resin in a specific weight as described above, it works to moderately increase the elastic modulus and shift the peak temperature of η from the low temperature side to around room temperature. This is because the value of η can be maintained at 0.03 or more at 0°C to 100°C. In this respect, among the above-mentioned non-thermosetting phenolic resins, cashew-modified phenolic resins are preferred. Also,
If the amount of non-thermosetting phenolic resin is less than 10 parts by weight, it will be less effective in shifting the peak temperature of η of NBR to the high temperature side (near room temperature), and if it exceeds 90 parts by weight, the properties as a rubber-like viscoelastic body will deteriorate. is damaged,
The temperature range in which the vibration damping effect is exerted becomes rapidly narrower. The thickness of the steel plate is not particularly limited, but
A relatively thin material of about 0.4 to 1.5 mm is used, and the thickness of the viscoelastic material is 0.1 to 1.0 mm depending on the thickness of the steel plate.
It is appropriately selected and used within a range of about mm. Furthermore, the steel plate and the viscoelastic body are bonded together by heating and vulcanization using a vulcanizing adhesive that has been applied to the steel plate surface in advance, and has a strong adhesive force with a T-peel strength of approximately 5 to 25 kg/cm. combined. In addition to the above-mentioned components, fillers, reinforcing agents, softeners, anti-aging agents, vulcanization accelerators, vulcanizing agents, etc. are appropriately blended into the viscoelastic body in the present invention. [Effects of the Invention] As explained above, in the present invention, a material having a peak of η on the low temperature side, this peak being broad and having small temperature dependence, and having excellent oil resistance.
By using a viscoelastic material made by blending a specific amount of non-thermosetting phenolic resin with good compatibility with NBR as an intermediate layer between two steel plates, the mechanical properties of the viscoelastic material can be improved. It is possible to shift the peak of η to around room temperature (10 to 25°C) without losing strength, and it is possible to maintain the value of η at 0.03 or more at 0°C to 100°C. The viscoelastic material forming the intermediate layer has no flow phenomenon at high temperatures, and the viscoelastic material itself is thermosetting, so that it is firmly bonded to the body by vulcanization adhesion. The steel plate has excellent durability and does not slip off at all. The damping steel plate of the present invention can sufficiently withstand mechanical processing such as shearing and press working. [Example] Examples of the present invention are shown below. A vulcanized adhesive was applied to the surfaces of two steel plates (thickness 0.7 mm) to which the viscoelastic body was attached, and a viscoelastic body having the composition shown in Table 1 was interposed between the two steel plates.
A damping steel plate was obtained by vulcanization at ℃ for 30 minutes. The thickness of the viscoelastic body is 0.5 mm. Table 1 also lists the mechanical properties of the viscoelastic body. Further, Table 2 shows the results of investigating the damping properties, adhesive properties, oil resistance, etc. of the damping steel plate. Incidentally, the damping characteristics were measured by a mechanical impedance method. The adhesive properties were measured by bending the ends of the steel plate in opposite directions and performing so-called T-peeling. Oil resistance was determined by immersing a test piece (a damping steel plate cut into 50 mm squares) in lubricating oil (100°C x 168 hours) and examining the degree of swelling of the viscoelastic body. As is clear from the results in Tables 1 and 2, all of the examples are excellent in vibration damping properties, adhesive properties, oil resistance, and mechanical properties (viscoelastic body), whereas the comparative examples Not only are they inferior in vibration damping properties, but they also have quite a few shortcomings in other properties as well. In addition, for the products of Example and Comparative Example 1, a predetermined load was applied to them in the shearing direction, and 100
When left in a ℃ atmosphere, the steel plate of Comparative Example 1 slipped off after 24 hours, while the steel plates of Examples remained normal even after 168 hours.

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Claims (1)

[Scope of Claims] 1. A vibration-damping steel plate characterized in that a viscoelastic body made of acrylonitrile-butadiene copolymer rubber mixed with a non-thermosetting phenolic resin is sandwiched between two steel plates. 2 Add non-thermosetting phenolic resin to 100 parts by weight of acrylonitrile-butadiene copolymer rubber.
The vibration-damping steel plate according to claim 1, which contains 10 to 90 parts by weight to form a viscoelastic body. 3. The damping steel plate according to claims 1 and 2, wherein the non-thermosetting phenolic resin is a cashew-modified novolak type phenolic resin.