JPH03119063A - Viscoelastic resin composition for vibration damper - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in bond strength and vibration damping performance, good in electrical resistance weldability by incorporating a viscoelastic vibration damping resin with electrically conductive granules and inorganic powder of specific mean granular size. CONSTITUTION:The objective composition suitable for making up a viscoelastic interlayer for composite vibration dampers can be obtained by incorporating (A) 100 pts.wt. of a viscoelastic vibration damping resin (e.g. epoxy-crosslinked polyester resin) with (B) electrically conductive granules (e.g. nickel powder, nickel-plated glass granules, carbon black) and (C) inorganic powder with its mean granular size being <=1/3 of the thickness of the intermediate resin layer of the above mentioned vibration damper [pref. 1-250 (esp. 1-150) pts.wt. of calcium carbonate, or 1-50 (esp. 1-25) pts.wt. of silica, or 1-50 (esp. 1-25) pts.wt. of kaolin].

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a viscoelastic resin composition for vibration damping materials, and more specifically for use as structural members or parts of various structures such as machines, buildings, and vehicles. The present invention relates to a viscoelastic resin composition for a vibration damping material used as an intermediate layer in a multi-layered vibration damping material.

[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 also a trend in workplaces to regulate noise and vibration in order to improve the working environment. In response to this trend, we are developing vibration damping performance for metal materials that are noise sources and vibration sources, that is, converting the vibration energy of the noise-generating member itself into thermal energy to attenuate the vibration speed or vibration amplitude. , there is a need to add a function to reduce acoustic radiation and to further improve this function.

Based on such demands, as one type of damping material that exhibits such performance, a composite damping material having a multilayer structure in which a viscoelastic intermediate layer is sandwiched between metal layers has been devised. These composite vibration damping materials are used in automobile oil pans, engine covers, dash panels, hopper chutes, stoppers for conveyor equipment, home appliances, vibration reduction members for other metal processing machines, and precision machinery where vibration prevention is desired. It has been studied and adopted for structural members, etc.

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 damping performance is expressed by a loss coefficient, it is known that this damping performance shows a peak characteristic at a certain constant temperature, and is most effective when used near this peak characteristic temperature.

Conventionally, as a viscoelastic composition constituting the viscoelastic intermediate layer of such a composite damping material, for example, polyester alone (
JP-A-50-143880), polyester with a plasticizer added (see JP-A-51-93770), polyurethane foam alone (JP-A-51-93770),
91981), polyamide alone (Japanese Patent Application Laid-open No. 1983)
-159160), ethylene-vinyl acetate copolymer alone (see JP-A-57-34949), polyvinyl butyral, or a composition of polyvinyl butyral and polyvinyl acetate mixed with a plasticizer and a tackifier. (see Japanese Patent Publication No. 55-27975), copolymers of isocyanate prepolymer and vinyl monomer (see Japanese Patent Publication No. 52-26554), and furthermore
Copolymers disclosed in Japanese Patent Publication No. 12451, Japanese Patent Publication No. 45-34703, and Japanese Patent Application Laid-Open No. 62-74645 are known.

In addition, in vibration damping steel plates whose skins are steel plates, conductive metal powder is added to the intermediate resin layer for the purpose of ensuring electrical resistance weldability (Japanese Unexamined Patent Application Publication No. 79920/1983). Publication No. 53-128687, Japanese Patent Publication No. 57-51
453, JP 61-290044, JP 62-87341, JP 62-90236, JP 62-151332, JP 63-
67142, JP 63-74634, JP 63-158243, JP 63-1700
No. 31, JP-A-63-188040, etc.), or those using graphite and/or carbon-based particles as conductive substances in the intermediate resin layer (JP-A-62-154405).
JP-A No. 63-158242, etc.) are known.

[Problem to be solved by the invention]

By the way, first of all, composite damping materials are required to have a high value of loss coefficient and high adhesive strength between the viscoelastic intermediate layer made of a viscoelastic composition and the metal layer. but,
Composite vibration damping materials manufactured using the above-mentioned conventional viscoelastic compositions have problems in all of their performances and are not fully satisfactory. In particular, in order to exhibit high vibration damping performance near room temperature, it is necessary to set the glass transition temperature below room temperature, and with conventional known resins, lowering the glass transition temperature significantly reduces the adhesive strength.
It could not be used in applications requiring high adhesiveness.

In addition, in the case of vibration-damping steel plates that use steel plates as the skin material, it is necessary to have electric resistance weldability in addition to the above characteristics.
In conventional viscoelastic resins, when conductive particles are added to impart electrical resistance weldability, the adhesive strength tends to be significantly lower than when the resin is used alone.

Therefore, in view of the above-mentioned state of the prior art, the viscoelastic resin composition for damping steel plates of the present invention has high adhesive strength at room temperature and maintains high vibration damping performance near room temperature.
It is an object of the present invention to develop a viscoelastic resin composition for damping materials that can provide good electrical resistance weldability.

[Means to solve the problem]

The present invention is a viscoelastic resin composition for a vibration damping material, which is made by blending conductive particles and an inorganic powder component with an average particle size of 1/3 or less of the resin layer thickness into a viscoelastic vibration damping resin. In particular, as an inorganic powder component, per 100 parts by weight of resin solid content,
1 to 250 parts by weight of calcium carbonate, more preferably 1 to 250 parts by weight
150 parts by weight of silica, or as an inorganic powder component, 1 to 50 parts by weight, more preferably 1 to 25 parts by weight of silica, per 100 parts by weight of resin solids, or as an inorganic powder component, resin solids It is desirable that the amount of kaolin be 1 to 50 parts by weight, more preferably 1 to 25 parts by weight, per 100 parts by weight.

[Effect]

The viscoelastic damping resin used in the viscoelastic resin composition for damping material of the present invention is desirably of poor quality from the viewpoint of improving damping performance. Examples of such resins include non-grade polyester, non-grade polyamide, non-grade polyamideimide, polyimide, polyurethane, polyurethane urea,
Examples include polyurea, acrylic resin, epoxy resin, vinyl acetate resin, non-grade polyolefin resin, and blends and copolymers of various resins.

A crosslinking agent may be used for the purpose of improving adhesiveness at high temperatures.

The present invention is characterized in that an inorganic powder component is blended into the viscoelastic damping resin. By using the viscoelastic resin composition for vibration damping materials of the present invention as an adhesive for composite vibration damping materials, adhesive strength higher than that of the resin alone at room temperature can be obtained, and a high level of vibration damping performance can be ensured. be. It is thought that by filling the viscoelastic vibration damping resin with inorganic powder, the rigidity of the entire resin increases, thereby improving the adhesive strength.

A wide range of inorganic powders can be used, but
It is preferable to use an inorganic powder that has little influence on the glass transition point of the viscoelastic vibration damping resin and does not adversely affect the vibration damping performance. In particular, calcium carbonate, silica, kaolin, carbon black, alumina, titanium oxide, zinc white, mica, graphite, etc. have desirable properties for the purpose of the present invention. These inorganic powders can exhibit similar effects when used alone or in a mixed state. The inorganic powder component added to the viscoelastic damping resin may be surface-modified with various surface modifiers for the purpose of improving interfacial adhesion with the resin. Examples of such surface modifiers include inorganic modifiers such as silane coupling agents and titanate coupling agents, and organic brimers.

The particle size of the inorganic powder component used in the present invention is 1 part of the intermediate resin layer thickness.
It is preferable to set the particle size to 1/3 or less, and by setting the particle size in this manner, it is possible to obtain an adhesive strength higher than that obtained when using the resin alone. If the particle size of the inorganic powder component used in the present invention exceeds 1/3 of the thickness of the intermediate resin layer, it is not preferable because the adhesive strength will decrease. This is considered to be because when the average particle size of the inorganic powder exceeds 1/3 of the resin layer thickness, defects tend to occur at the interface between the particles and the resin, resulting in a decrease in adhesive strength. For example, in the examples described below, the intermediate resin layer thickness is 0.
．． In the case of 05 mm, the effect of the present invention was observed up to calcium carbonate with a particle size of 14 μm, but the desired effect of the present invention was observed when using silica with a particle size of 17 μm, kaolin with a particle size of 21 μm, and calcium carbonate with a particle size of 90 μm. I can't. In addition, by adding calcium carbonate as an inorganic powder component in an amount of 1 to 250 parts by weight, more preferably 1 to 150 parts by weight, based on 100 parts by weight of the resin solid content, it is possible to avoid deteriorating vibration damping performance (adhesive strength). In this case, fine particles can be added in large quantities.The amount of calcium carbonate added exceeds 250 parts by weight per 100 parts by weight of resin solid content. If silica and kaolin are added, the amount of addition is 1 to 50 parts by weight, more preferably 1 to 50 parts by weight, based on 100 parts by weight of resin solid content. In the range of 25 parts by weight, it is possible to significantly improve the adhesive strength without reducing vibration damping performance.If the amount added exceeds the range of 1 to 50 parts by weight per 100 parts by weight of resin solid content, it is possible to improve the adhesive strength at room temperature. This is undesirable because the adhesion performance deteriorates markedly.If the amount of inorganic powder added exceeds a certain amount, both the adhesive strength and vibration damping performance decrease because the proportion of the viscoelastic vibration damping resin decreases. This is thought to be because the stress applied to the resin becomes too large.

The present invention is characterized in that conductive particles are further blended into the viscoelastic resin composition for the purpose of imparting electrical resistance weldability. By mixing and adding an inorganic powder component and conductive particles to the viscoelastic resin, it is possible to maintain high vibration damping performance while ensuring a higher adhesive strength than when using only the viscoelastic resin. It becomes possible to obtain good electric resistance weldability.

In the present invention, a wide variety of conductive particles can be used as the conductive particles, and although there are no particular limitations, these conductive particles can provide good conductivity. Particular preference is given to using metallic substances. Such particles include, for example, metal substances made of powdered stainless steel, copper, brass, nickel, etc., copper-plated glass particles, nickel-plated glass particles, or conductive carbon materials such as carbon black and graphite. Examples include substances. These conductive substances can be used alone or in combination of two or more. Further, in order to exhibit better conductivity, it is preferable that the thickness of the particles after being sandwiched between the vibration damping materials is 0.8 to 1.0 times the thickness of the intermediate resin layer.

The amount of conductive particles to be added is preferably 0.5 to 10% by volume relative to the intermediate layer, and as long as the amount is within this range, the adhesive strength will not be impaired.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

1 to 11 and 1 to 9 Epoxy crosslinked polyester resin is used as the basic resin, and nickel powder with an average particle size of 0.05 mm is used as an inorganic powder component and conductive particles as shown in Tables 1 and 2. In addition, a viscoelastic resin composition was created.

The created viscoelastic resin composition was sandwiched at a thickness of 0.05 mm between two 0.8 mm thick phosphate-treated steel plates to create a composite vibration damping metal plate, and its shear adhesive strength was measured according to JISK 68.
Measured according to No. 50. In addition, the vibration damping performance has a vibration frequency of 50
The loss coefficient at 082 was determined. Furthermore, regarding weldability, we attached the composite vibration damping metal plate to an actual welding machine.
A welding test was conducted under the conditions of 250 kgf, 9.6 kA, and 10 cycles, and the judgment was made.

Examples 1.2.3 and 4 are samples in which calcium carbonate having a particle size of 1.4 μm and conductive particles were added.

An increase in shear adhesive strength is observed compared to the samples of Comparative Examples 1 and 2 to which no inorganic powder component was added. In addition, the vibration damping performance has a loss coefficient of 0.1 or more near normal temperature,
Maintains high performance. Similarly, Examples 5 and 6 are samples in which calcium carbonate with a particle size of 14 μm and conductive particles are added, Examples 7 and 8 are samples in which silica with a particle size of 2.6 μm and conductive particles are added, Examples 9 and 10 are samples in which kaolin with a particle size of 2.5 μm and conductive particles were added, and the shear adhesive strength increased compared to the samples of Comparative Examples 1 and 2, in which no inorganic powder components were added. Is recognized. Example 11 is an example in which calcium carbonate, silica, and kaolin were mixed and added, and the performance did not deteriorate even if inorganic powder was mixed and added. Comparative examples 3, 4, 5,
6, 7.8 and 9 added conductive particles, and
This is a sample in which an excessive amount of inorganic powder component is added, or a sample in which an inorganic powder component whose particle size exceeds 1/3 of the thickness of the intermediate resin layer is added, and the shear adhesive strength is extremely low. In addition, some samples with damping performance of less than 0.1 were also observed.

〔Effect of the invention〕

The composite vibration damping metal plate made using the viscoelastic resin composition for damping material according to the present invention has a higher level of vibration damping than the composite vibration damping metal plate made using the viscoelastic resin composition containing no inorganic powder component.
It has high adhesive strength at room temperature, can maintain high vibration damping performance, and can also be used for electric resistance welding due to the conductive particles. Thus, the viscoelastic resin composition according to the present invention is extremely useful as a viscoelastic resin composition for vibration damping materials.

Margin below

Claims (1)

[Scope of Claims] 1. A control characterized by blending conductive particles and an inorganic powder component with an average particle size of 1/3 or less of the resin layer thickness into a viscoelastic vibration damping resin. Viscoelastic resin composition for vibration materials. 2. The viscoelastic resin composition for vibration damping materials according to claim 1, characterized in that 1 to 250 parts by weight of calcium carbonate is blended as an inorganic powder component with respect to 100 parts by weight of resin solid content. 3. The viscoelastic resin composition for vibration damping materials according to claim 1, characterized in that 1 to 50 parts by weight of silica is blended as an inorganic powder component with respect to 100 parts by weight of resin solid content. 4. The viscoelastic resin composition for vibration damping materials according to claim 1, wherein the inorganic powder component is 1 to 50 parts by weight of kaolin per 100 parts by weight of resin solid content.