JPH0524835B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides an adhesive layer on both sides of a sheet-like thermoplastic resin with vibration damping performance, and firmly bonds this sheet-like resin between two metal plates, especially two steel plates. The present invention relates to a composite vibration damping material which exhibits excellent vibration damping properties over a wide temperature range around room temperature and also exhibits excellent moldability. (Conventional technology) Traditionally, construction materials, vehicles, ships,
Various vibration damping materials have been proposed and put into practical use for the purpose of preventing vibrations and noise accompanying vibrations in home appliances and the like. Among these, the Sanderch-type composite vibration damping steel plate, in which a viscoelastic resin is sandwiched between two steel plates, has the excellent mechanical properties of steel and the excellent vibration damping performance of a viscoelastic resin.
It is an excellent structural material and has a wide range of uses. The performance of vibration-damping steel plates largely depends on the core material resin, and examples of core material resins include polyisobutylene, olefin hydrocarbon resin (Japanese Patent Application Laid-Open No.
43251), butyl rubber (Japanese Patent Publication No. 59-52644), polyvinyl chloride (Japanese Patent Publication No. 51-22781), polyvinyl acetal (Japanese Patent Publication No. 54-23489), acrylonitrile-butadiene copolymer rubber/epoxy resin ( JP-A No. 60-245550) and many others have been reported. However, although many of these conventional core material resins have high vibration damping performance around a certain temperature,
Most of them are applicable in the so-called medium to high temperature range, and they have the disadvantage of poor vibration damping performance near room temperature. In addition, a large amount of plasticizer is added to exhibit vibration damping performance near room temperature (Special Publication No. 54-23489).
JP-A No. 52-63253) was also proposed, but in this case there were problems such as oozing of the plasticizer or a decrease in the adhesive strength between the resin and the steel plate. (Problems to be Solved by the Invention) The present invention aims to solve the following two problems in composite vibration damping materials, particularly vibration damping steel plates. (1) The application temperature of damping steel plates should be wide range around room temperature: In general, damping steel plates are most often used around room temperature, but if regional and seasonal differences are taken into consideration, -20 It is necessary to exhibit sufficient vibration damping performance in the temperature range of ~+50°C. In other words, it is well known that vibration damping performance is affected by temperature, and even if the temperature changes within the above range, the loss coefficient (η) for 500Hz
to maintain at least 0.05 or higher. (2) Improving the adhesive strength between the steel plate and the core resin: Generally, vibration-damping steel plates are manufactured into products such as oil pans and engine covers by being subjected to plastic processing using a press, etc., in the same way as conventional steel plates. However, if the adhesive strength between the steel plate and the core resin is not sufficient, openings and wrinkles may occur due to misalignment and peeling during press working, bending, etc., and the concrete molded product cannot be used as Therefore, the adhesive strength should be 10Kgf/25mm or more in the T-peel test. (Means for Solving the Problems) In the present invention, in a composite vibration damping material in which an adhesive layer is provided on both sides of a sheet-shaped thermoplastic resin, and this sheet-shaped resin is bonded between two metal plates, (1) An acrylonitrile thermoplastic elastomer is used as the sheet-like thermoplastic resin that is the core resin, and (2) the -NCO/-OH molar ratio is in the range of 0.1 to 5.0 on both sides of the core resin. The above object is achieved by providing an adhesive layer formed by blending an isocyanate compound with a thermoplastic polyester adhesive. (Function) Vibrations of various frequencies are applied to the composite vibration damping material of the present invention depending on its use, but considering vibration mainly due to sound, there are many relatively low frequency components, so 500 Hz is used as the standard frequency. The vibration damping performance for this frequency, that is, the loss coefficient (η)
In the present invention, vibration damping performance is defined as at least 0.05 or more. A condition for the composite vibration damping material of the present invention is to be able to exhibit such damping performance even in a wide temperature range (-20 to +140°C) around room temperature. In addition, in the present invention, the sheet-shaped core material resin used to ensure the above-mentioned vibration damping performance is
Use an acrylonitrile thermoplastic elastomer that has a compression set of 45% or less when measured for 22 hours and a hardness (according to JIS K6301 - Vulcanized rubber physical test method - Spring hardness test type A) of 60 or less. . However, since this acrylonitrile thermoplastic elastomer does not have adhesive properties to metal plates such as steel plates, it is essential to use an adhesive in combination. It goes without saying that the adhesive used for this purpose is limited to those that can exhibit adhesion to both a metal plate such as a steel plate and an acrylonitrile thermoplastic elastomer. , -NCO/-OH molar ratio is 0.1~
Use an adhesive made by blending an isocyanate compound with a thermoplastic polyester adhesive so that the viscosity is in the range of 5.0. -NCO/-OH molar ratio in adhesive is 0.1~
A range of 5.0 is suitable, but a range of 0.5 to 2.0 is particularly preferred. If the -NCO/-OH molar ratio is less than 0.1, that is, if the -OH groups are in excess, the adhesive layer becomes too soft and the adhesive strength decreases. Furthermore, if the -NCO/-OH molar ratio exceeds 5.0, that is, if the -NCO group is excessive, the adhesive layer becomes too hard and cracks occur during molding, which is disadvantageous. The isocyanate compound used in the present invention may be any commonly used organic polyisocyanate, but particularly representative ones include hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate (TDI), and diphenyl diisocyanate. Methane diisocyanate (MDI), naphthalene diisocyanate (NDI), xylene diisocyanate (XDI), and alcohol-denatured isocyanates (typically, tolylene diisocyanate modified with trimethylolpropane): Products There is a name called Coronate L). Further, the thickness of the thermoplastic elastomer and the thickness of the adhesive layer used in the present invention are not particularly limited, but from the comprehensive viewpoint of vibration damping performance, adhesiveness, and moldability, the thickness of the thermoplastic elastomer is
The thickness of the adhesive layer is preferably 5 to 20 μm on one side. This is because, if the content is outside this range, any one of the properties of vibration damping performance, adhesiveness, and moldability will deteriorate. The acrylonitrile thermoplastic elastomer used as the core resin in the present invention includes:
As in ordinary thermoplastic elastomers,
It is of course possible to use various colorants in combination with stabilizers, fillers, plasticizers, etc. However, in any case, if excessively added, there is a risk that the desired properties as a vibration-damping steel plate will be lost, so consideration must be given to the amount used. (Example) Next, the present invention will be described with reference to Examples and Comparative Examples. In these examples and comparative examples, degreased steel plates (0.6 mm thick) were used, and the adhesive was applied with a brush or roller until the dry thickness was reduced to one side.
It was coated to a thickness of 10 μm. All sheets with a thickness of 100 μm were used as the core resin, and thermoplastic elastomer of the following grade was used. Acrylonitrile elastomer Denka LCS Z-1050: Denka Kagaku Kogyo Co., Ltd. Denka LCS Z-1060: Denka Kagaku Kogyo Co., Ltd. Denka LCS Z-4250: Denka Kagaku Kogyo Co., Ltd. Vinyl chloride elastomer Denka Reomer G- 5655: Manufactured by Denki Kagaku Kogyo Co., Ltd. Each measurement value was measured and judged according to the following conditions. 1) Temperature dependence of loss coefficient (η) (damping performance): After placing a composite damping steel plate sample in a constant temperature chamber, using a frequency of 500 Hz, we measured the resonance point for each set temperature in order from the low temperature side. The sharpness was determined using the mechanical impedance method, and the temperature range in which the loss coefficient (η) was 0.05 or more was determined. 2) T-type peel strength (adhesive strength): JIS k-6854 3) Formability: Using an Excelin tester, a cylindrical deep drawing ratio of 2.0 or more was considered to be a pass. Example 1 Adhesive A (manufactured by Toyobo Co., Ltd., product name: Vylon)
After applying an adhesive with a -NCO/-OH molar ratio of 1.0 obtained by blending isocyanate compound C (manufactured by Nippon Polyurethane Industries Co., Ltd., product name: Coronate L) with 300) on the inside of two steel plates. A sheet-like acrylonitrile thermoplastic elastomer of the grade shown in Table 1 was sandwiched between two steel plates in a sandwich structure, and the sheets were pressed together using a hot press at 160° C. for 10 minutes. The temperature dependence of loss coefficient at 500 Hz, T-peel strength, and formability of the obtained composite damping steel plate were measured, and all showed satisfactory performance. Comparative Example 1 A composite damping steel plate was created using the same conditions as in Example 1, except for the type of elastomer that was the core material resin. Although a vinyl chloride elastomer that does not contain acrylonitrile was used as the core resin, all of the composite damping steel plates obtained had low vibration damping performance in the low temperature range and could not achieve the target value. Example 2 Same elastomer LCS Z- as Example 1(1)
1050 and using adhesive B (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., Polyester LP-033) instead of adhesive A, or using the same adhesive A.
Composite vibration-damping steel plates were created in which the NCO/-OH molar ratio was changed to 0.5 or 2.0 within the range of 0.1 to 5.0. Under all conditions, although there was some variation in adhesive strength, the target value could be achieved. Example 3 Isocyanate compound D (Nippon Polyurethane Industry Co., Ltd.) was used instead of isocyanate compound C in Example 1.
A composite vibration damping steel plate was produced under the same conditions as in Example 1(1) except that Coronate 2030 (trade name: Coronate 2030) or E (trade name: Coronate HL), manufactured by the same company, was used. In both cases, results satisfying the target values were obtained. Comparative example 2 -NCO/-OH molar ratio outside the range of 0.1 to 5.0
A composite damping steel plate was produced under the same conditions as in Example 2(2) or 2(3) except that the value was changed to 0.05 or 7.0. Although the target value for vibration damping performance was achieved, in all cases the adhesive strength was weak and the moldability was poor.

【table】

[Table] (Effects of the invention) The vibration damping steel plate of the present invention exhibits excellent vibration damping performance in a wide temperature range (-20 to +50°C) near room temperature, which is the most frequently used area, and also has extremely high adhesive strength. Therefore, it can be used extremely well even in areas where deep drawing is required.

Claims (1)

[Scope of Claims] 1. A composite vibration damping material in which an adhesive layer is provided on both sides of a sheet-shaped thermoplastic resin, and the sheet-shaped resin is bonded between two metal plates, (1) the sheet-shaped thermoplastic resin is bonded between two metal plates; the resin is an acrylonitrile-based thermoplastic elastomer; 1. A composite vibration damping material characterized by being an adhesive layer formed by blending so that the molar ratio -NCO/-OH with respect to the group is 0.1 to 5.0.