JPS62152750A - Viscoelastic composition for vibration-damping material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a viscoelastic composition for vibration damping materials, and more particularly to structural members of various structures such as machines, buildings, and vehicles, or parts thereof. The present invention relates to a viscoelastic composition for a vibration damping material used as an intermediate layer in a three-layer vibration damping material used as a third layer.

[Conventional technology]

In recent years, with the development of transportation systems and the proximity of residences to factories, noise and vibration problems have become a social problem as pollution. There is a tendency to regulate. In response to these trends, we are developing vibration damping performance for metal materials that are noise sources and vibration sources, that is, absorbing the vibration energy of the noise-generating components themselves and converting them into thermal energy, increasing the vibration speed or vibration amplitude. There is a need to provide and improve the function of attenuating acoustic radiation and reducing acoustic radiation.

Based on these demands, one type of damping material that exhibits such damping performance is a composite vibration damping material with a three-layer structure in which a viscoelastic intermediate layer is sandwiched between two metal layers. is proposed.

This composite damping material is used in automobile oil pans,
It has been studied and adopted for engine covers, hopper chutes, stoppers for transport equipment, home appliances, vibration reduction members for other metal processing machines, and structural members for precision machinery where vibration prevention is desired.

Generally, the damping performance of such a composite vibration damping material depends on the performance of the viscoelastic intermediate layer that constitutes the intermediate layer.

When this vibration damping performance is expressed as a loss coefficient (m, which is a measure of the conversion of external imaging energy into thermal energy due to internal friction and is related to mechanical hysteresis loss due to vibration), this vibration damping performance peaks at a certain temperature. showing the characteristics,
It is known that it is most effective to use it near this peak characteristic temperature.

Conventionally, as a viscoelastic composition constituting the viscoelastic intermediate layer of such a composite vibration damping material, polyamide (Japanese Unexamined Patent Application Publication No. 1983-1999) has been used as a viscoelastic composition.
159.160), ethylene-vinyl acetate copolymer (JP-A-57-34.949), polyvinyl butyral, or a composition of polyvinyl butyral and polyvinyl acetate mixed with a plasticizer and a tackifier. thing(
(Japanese Patent Publication No. 55-27.975), Copolymer of isocyanate prepolymer and vinyl monomer (Japanese Patent Publication No. 52-27-975)
26.554) etc. are known.

[Problem that the invention seeks to solve]

By the way, the characteristics required for composite vibration damping materials are as follows:
First of all, it is required that the value of the loss coefficient is high and the adhesive strength between the viscoelastic intermediate layer made of the viscoelastic composition and the metal layer is high, but the conventional viscoelastic composition described above is required. Composite vibration damping materials manufactured using synthetic materials have problems in terms of their performance and have not been fully satisfactory.

[Means to solve the problem]

The present invention was created in view of this point of view, and is a viscoelastic composition that exhibits good adhesion to metal materials and that can be used as a viscoelastic intermediate layer and provide excellent vibration damping performance. It provides:

That is, the present invention provides a control compound comprising 20 to 300 parts by weight of an inorganic filler per 100 parts by weight of a terpolymer of ethylene, an unsaturated carboxylic acid, and an ester or vinyl ester of an unsaturated acid. This is a viscoelastic composition for vibration materials.

In the present invention, the vibration damping material is a composite vibration damping material having a so-called three-layer structure in which a viscoelastic intermediate layer that connects these metal layers to each other is sandwiched between two metal layers. The metal material forming the metal layer may be any material that faces each other and constitutes a vibration damping material with a viscoelastic composition sandwiched between them; for example, two metal plates, two concentric metal tubes, Examples include two shaped steels, two molded bodies that can be stacked on top of each other, a metal molded body and a backing plate, and other two-layered structures. Examples of metals mentioned here include iron, copper, aluminum, etc., and commonly used metals include steel materials, aluminum, and alloys thereof. Moreover, these metal materials may be surface-treated such as plated steel plates.

The viscoelastic intermediate layer sandwiched between the two metal layers formed by the above-mentioned metal material is composed of a viscoelastic composition made of a specific resin and an inorganic filler.

The resin constituting this viscoelastic composition is a terpolymer of ethylene, an unsaturated carboxylic acid, and an ester or vinyl ester of the unsaturated acid. Here, the unsaturated carboxylic acid is a crosslinking point monomer, and includes, for example, acrylic acid, methacrylic acid, and the like, as well as monoalkyl esters such as maleic acid and fumaric acid. In addition, examples of esters of unsaturated acids include alkyl esters of acrylic acid and methacrylic acid, and typical examples include methyl acrylate, ethyl acrylate, isobutyl acrylate, and ethyl methacrylate. Methyl acrylate is preferred. Further, a typical vinyl ester is vinyl acetate. A specific example of a terpolymer suitable for the viscoelastic composition of the present invention is Bemac (trade name) manufactured by De Bont.

The above terpolymer of ethylene, unsaturated carboxylic acid, ester of unsaturated acid, or vinyl ester can be vulcanized with amine, and if necessary, hexamethylene diamine, 4.
Vulcanization is carried out using a diamine vulcanizing agent such as 4-methylene dianiline or a guanidine accelerator such as diphenylguanidine or diorthotolylguanidine. This vulcanization shifts the peak characteristic temperature of the loss factor slightly to the higher temperature side, but
It has almost no effect on the value of the stone fire coefficient.

The above terpolymer does not exhibit sufficient adhesion to metal materials, regardless of whether it is vulcanized or not. However, by adding an inorganic filler to this terpolymer, it exhibits sufficient adhesion to metal materials. Examples of such inorganic fillers include calcium carbonate, magnesium carbonate, barium sulfate, alumina, silica, iron oxide, titanium oxide, talc, clay, mica, slag, glass fiber, white carbon, reinforcing carbon black, and stone. Examples include N. These inorganic fillers may be used alone, or two or more types may be appropriately combined and used as a mixture. Furthermore, clay is particularly preferred for improving the adhesion between the viscoelastic composition constituting the intermediate layer and the metal material, and it is preferred to use this clay as a component of the inorganic filler.

Furthermore, conductivity can be imparted to the above terpolymer by blending a conductive solid substance as a filler, and the resulting damping material can be made into a material that can be spot welded. Conductive solid materials used for this purpose include, for example, metals such as SUS, copper, brass, and nickel processed into powder, flake, fiber, and wire shapes, and copper-plated glass. Examples include flakes, fibers, flakes of nickel-plated glass, and other metal-plated materials, and conductive carbonaceous materials such as electrically conductive carbon black, graphite, and carbon fiber.

The blending ratio of the terpolymer and inorganic filler is usually 20 to 300 parts by weight, preferably 20 to 240 parts by weight, per 1 part by weight of the terpolymer. It is. If the blending ratio of the inorganic filler is less than 20 parts by weight based on the terpolymer, the effect of blending the inorganic filler will not be sufficient; on the other hand, if it exceeds 300 parts by weight, the resulting intermediate layer will be hard. If it becomes too much, the adhesion with the metal material decreases. When an inorganic filler is blended into a terpolymer, the peak characteristic temperature of the loss factor may shift to a higher temperature side as the blending ratio increases, but the blending amount of the inorganic filler may vary depending on the viscoelastic composition. It is determined by considering both the adhesion between the constituent intermediate layer and the metal material and the peak characteristic temperature required of the damping material.

Third additives such as tackifiers, plasticizers, antioxidants, and processing aids can be added to the viscoelastic composition as required.

The tackifier has the effect of improving the tackiness of the viscoelastic composition and shifting the peak characteristic temperature of the loss coefficient in the damping material to a higher temperature side. As this tackifier, for example,
Examples include alkylphenol resin, terpenephenol resin, rosin, rosin ester, hydrogenated rosin ester, coumaron-indene resin, phenol-modified coumaron resin, petroleum resin, etc. Among them, coumaron-indene resin is preferred for improving adhesiveness. These are coumaron resins such as indene resin and phenol-modified coumaron resin.

These tackifiers may be used alone or as a mixture of two or more, if necessary. The usage time of this tackifier is determined appropriately depending on the peak characteristic temperature of the required loss coefficient, etc., but it is usually 0 to 150 parts by weight per 100 parts by weight of the above terpolymer. Preferably O~1
This tackifier is added to the terpolymer at the center of gravity at 20 times the center of gravity.
If 150 parts by weight or more is used relative to 0 parts by weight, the intermediate layer constituted by the viscoelastic composition will become too hard and the adhesiveness will decrease.

Furthermore, plasticizers are used for the purpose of facilitating the blending of the terpolymer and the inorganic filler, improving low-temperature properties, or shifting the peak characteristic temperature of the loss coefficient to the low-temperature side, such as , polyester plasticizers, polyether ester plasticizers, and diester plasticizers such as dioctyl azelate and dioctyl sebacate. Furthermore, as antioxidants, phosphorus ester antioxidants,
Hindered phenolic antioxidants and tophenyl-N
'-CD-toluenesulfonyl)-p-phenylenediamine, N,N'-di(naphthyl)-p-phenylenediamine, 4,4'-bis(α,α-dimethyl)-p-phenylenediamine, 4, Examples include amine-based antioxidants such as 4'-bis(α,α-dimethylbenzyl)diphenylamine, and amine-based antioxidants are preferred.

Furthermore, processing aids are used to improve workability when mixing a terpolymer and an inorganic filler, or to gel a viscoelastic composition when it is used in a coated form. For example, stearic acid, stearylamine, etc. are used to prevent this, and these may be used alone or in combination of two or more as necessary.

〔Example〕

Hereinafter, the viscoelastic composition of the present invention will be explained based on Examples and Comparative Examples.

Examples 1 to 4 and Comparative Examples 1 to 3 As a ternary copolymer consisting of ethylene, an unsaturated carboxylic acid, and an ester or vinyl ester of an unsaturated acid, a ternary copolymer consisting of ethylene, methyl acrylate, and an unsaturated organic acid was used. A polymer (product name: Beamatsuku ■ manufactured by DuPont) is used, calcium carbonate or clay is used as an inorganic filler, coumarone resin is used as a tackifier, and diphenylguanidine +4,4°- as a crosslinking agent. Methylene dianiline was used as an antioxidant with 4,4°-bis(α,
α-dimethylbenzyl)diphenylamine and stearylamine as a processing aid were used in the proportions shown in Table 1. Dissolving the above terpolymer in xylene,
The above-mentioned inorganic filler and various additives were mixed with this and dispersed in a sand mill to prepare a viscoelastic composition.

The obtained viscoelastic composition was sandwiched between two steel plates having a thickness of 0.8#, and the two steel plates were bonded together to obtain a composite damping material as a test piece. The thickness of the intermediate layer of the viscoelastic composition in this test piece was 80 μm.

For each test piece obtained, the T-peel strength and tensile shear strength were determined using a tensile tester, and the damping performance was evaluated by determining the peak characteristic temperature and loss coefficient using the mechanical impedance method. The results are shown in Table 1.

Further, Comparative Examples 1 to 3 show cases in which the above terpolymer was used and no inorganic filler was blended.

The maximum value of the loss factor is not significantly affected by the presence or absence of an inorganic filler, but the adhesive strength is greatly affected by the inorganic filler.
The value is small regardless of whether a tackifier or crosslinking agent is used.

The results are shown in Table 1.

〔Effect of the invention〕

The viscoelastic composition of the present invention is sandwiched between two metal plates to form an intermediate layer that exhibits excellent adhesion and vibration damping performance, so it can be used as a viscoelastic composition for producing a composite vibration damping material. It is extremely useful as a material.

Patent applicant Nippon Steel Chemical Co., Ltd. Same as above
Nippon Steel Corporation Representative Patent Attorney Katsuo Naruse (2 others)

Claims (2)

[Claims] (1) Viscous material for vibration damping material containing 20 to 300 parts by weight of an inorganic filler to 100 parts by weight of a terpolymer of ethylene, an unsaturated carboxylic acid, and an ester or vinyl ester of an unsaturated acid. Elastic composition. (2) The viscoelastic composition for a vibration damping material according to claim 1, wherein one component of the inorganic filler is clay.