JPH0441705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a viscoelastic composition for producing a composite vibration damping material, and more particularly, it relates to a viscoelastic composition for producing a composite vibration damping material, and more specifically for use in a viscoelastic composition for producing a component of a machine or a structure, or a part thereof. The present invention relates to a viscoelastic composition used in the production of a composite vibration damping material with high vibration absorption ability that can reduce vibrations and noise of machines and structures.

[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, and noise and vibration regulations have also been implemented in workplaces with the aim of improving the working environment. There is a tendency to In response to such trends, it is required to provide vibration damping performance to metal materials that are sources of noise and vibration, and to improve the vibration damping performance.

Therefore, a composite vibration damping material having a three-layer structure in which a viscoelastic intermediate layer made of a viscoelastic resin is sandwiched between two metal layers has been proposed as one of the materials that exhibit such vibration damping performance. For example, it has been considered and adopted for use in automobile oil pans and engine covers, hopper chute parts, transport equipment stoppers, home appliances, vibration reduction parts for other metal processing machines, and structural parts of precision machinery where vibration prevention is desired. has been done.

Note that the composite vibration damping material referred to herein has a so-called three-layer structure in which a viscoelastic intermediate layer for bonding these metal layers to each other is sandwiched between two metal layers. The metal materials constituting the two metal layers may be any metal material that faces each other and can form a damping material by sandwiching a viscoelastic resin between them. For example, two metal plates, two concentric Examples include metal tubes, two steel sections, two molded bodies that can be stacked on top of each other, a metal formed body and a backing plate, and other two-layered structures. The metal forming the metal layer mentioned here is not particularly limited, but usually iron,
It may be aluminum, copper, lead, or alloys containing these as one component, metal materials plated with zinc, tin, chromium, etc., and surfaces treated with epoxy resin, melamine resin, etc. .

By the way, the damping performance of such a composite damping material generally depends on the performance of its viscoelastic intermediate layer, and this damping performance is determined by a loss coefficient (external vibration energy is converted into thermal energy due to internal friction). It is known that when expressed as a conversion scale (quantity related to mechanical hysteresis loss due to vibration), it usually shows a peak characteristic at a certain temperature, and the best vibration damping performance is exhibited near this peak characteristic temperature. There is.

As the viscoelastic resin constituting the viscoelastic intermediate layer of such a composite damping material, polyamide (Japanese Patent Application Laid-Open No. 159160/1982) and ethylene-vinyl acetate copolymer (Japanese Patent Application Laid-open No. 57-34949) are used. Publications), polyvinyl butyral or blends of polyvinyl butyral and polyvinyl acetate with plasticizers and tackifying substances (Japanese Patent Publication No. 1983-27975), copolymers of isocyanate prepolymers and vinyl monomers (Japanese Patent Publication No. 55-27975), (Japanese Patent Publication No. 52-26554), olefin resin multilayer body (Japanese Patent Publication No. 60-82349), compositions of saturated polyester resins mixed with organic peroxides and fillers as crosslinking agents (Japanese Patent Publication No. 53-9794) Publication No.),
Resin compositions of polyester resin or polyester resin and polyolefin resin
-89842) etc. are known.

[Problem that the invention seeks to solve]

By the way, the first characteristic required of a composite damping material is high damping performance, which is generally expressed by the magnitude of the loss coefficient. Second, since the composite damping material is used as a structural member and also undergoes secondary processing such as press processing, the adhesive strength between the viscoelastic intermediate layer made of viscoelastic resin and the metal layer is In particular, high shear adhesive strength is also required. Furthermore, thirdly, the composite vibration damping material that has undergone press processing may undergo a baking coating process in which it is heated to about 200°C, and it is also required that the viscoelastic intermediate layer does not wash away at around the above temperature.

Composite vibration damping materials manufactured using the above-mentioned conventional viscoelastic compositions have some problems in performance and are not fully satisfactory.

In particular, in the case of a damping material that exhibits excellent damping performance in the room temperature range of 0°C to 60°C, the glass transition region of the viscoelastic intermediate layer resin composition must be at or below room temperature, and the elastic modulus at room temperature is It has a low composition. On the other hand, compositions exhibiting a high elastic modulus are generally superior in terms of shear adhesive strength, which has an important effect on press workability. In other words, vibration damping performance, which is the first required property required for composite vibration damping materials, and shear adhesive strength, which is related to press workability, are contradictory properties regarding the elastic modulus of the viscoelastic intermediate layer resin. However, there has been no material that fully satisfies both of these characteristics.

In addition, amorphous polyester resin is known to have excellent adhesion to metal materials, but it is especially important to use resins with a low glass transition temperature that exhibit vibration damping performance at room temperature. In this case, the shear adhesive strength does not show a value high enough to withstand press processing, and there are problems such as a decrease in adhesive strength at high temperatures. Furthermore, even if a commonly used isocyanate crosslinking agent is used, the shear adhesive strength is insufficient. The shear adhesive strength of the composition also does not show a value high enough for the obtained vibration damping material to withstand press processing.

[Means for solving problems]

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. The purpose of the present invention is to provide a viscoelastic composition that can satisfy two contradictory properties, particularly vibration damping performance in the room temperature range and shear adhesive strength that affects press workability.

That is, the present invention provides for 100 parts by weight of an amorphous polyester having a maximum value of loss tangent (tan δ) based on glass transition of 0.5 or more and a temperature at which this maximum occurs between -40°C and 120°C. 1 to 40 acid anhydrides
This is a viscoelastic composition for a composite vibration damping material, which contains 1 to 50 parts by weight of an epoxy compound having two or more epoxy groups in one molecule. The present invention will be explained in detail below.

First, the viscoelastic composition in the present invention is composed of a specific resin, an acid anhydride, and an epoxy compound.
The resin constituting this viscoelastic composition is an amorphous polyester with a maximum loss tangent (tan δ) based on glass transition of 0.5 or more, and a temperature at which this maximum occurs between -40°C and 100°C. be.

The damping performance of a damping steel plate obtained using polyester having a maximum tan δ value of less than 0.5 based on glass transition is low and cannot be said to be practical. In addition, vibration damping steel plates are used for things that require vibration damping performance in the normal temperature range, such as automobile dashboard panels and floors, and for things that require vibration damping performance in the high temperature range of 80 to 100 degrees Celsius, such as around automobile engines. This is the main factor, and in order to achieve vibration damping performance in any of the above temperature ranges,
It is necessary that the temperature showing the maximum of tan δ is between -40°C and 120°C. Further, in order to exhibit vibration damping performance in the room temperature range, it is preferable that the maximum of tan δ based on glass transition is between -20°C and 60°C.

Such amorphous polyesters are produced by dissolving crystalline saturated polyesters such as polyethylene terephthalate and polybutylene terephthalate in ethylene glycol at high temperature.
It can be synthesized by adding a saturated polyhydric alcohol such as 1,4-butanediol or neopentyl glycol and performing a transesterification reaction, or by copolymerizing a saturated polyhydric carboxylic acid and a saturated polyhydric alcohol. It can also be synthesized. The latter saturated polycarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,6 naphthalenedicarboxylic acid, diphenyldicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and trimellitic anhydride. etc. are exemplified.
Examples of saturated polyhydric alcohols include ethylene glycol, 1,4 butanediol, 1,5 pentanediol, 1,6 hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, neopentyl glycol, propylene glycol, and 1,4 cyclohexanediol. Examples include methanol, pentaerythritol, trimethylol, propane and the like. There are many combinations of these monomers, and they are appropriately selected and used depending on the desired melting point, glass transition temperature, degree of amorphism, etc. In addition, these amorphous polyesters are
All of these amorphous polyesters have a functional group such as a hydroxyl group or a carboxyl group at the end, and two or more of these amorphous polyesters can also be used in combination.

Acid anhydrides and epoxy compounds are used together with the above amorphous polyester, and examples of the acid anhydrides include maleic anhydride, dodecenylsuccinic anhydride,
Chlorendecic anhydride, sebacic anhydride polymer,
Phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, cyclopentanetetracarboxylic dianhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride,
Methylendomethylenetetrahydrophthalic anhydride, 5-(2,5-dioxotetrahydroxyfuryl)-3-methyl-3-cyclohexane-1,
Examples include 2-dicarboxylic anhydride, methylnadic anhydride, benzophenonetetracarboxylic anhydride, and the like.

These acid anhydrides can be used alone or in combination of two or more, but in order to effectively crosslink the amorphous polyester and develop excellent shear adhesive strength, it is necessary to use at least one of the acid anhydrides. One component is preferably a polyfunctional compound having two or more anhydride groups in one molecule.

Epoxy compounds have two or more epoxy groups in one molecule, and include bisphenol A-based epoxy resins, tetrabromobisphenol A-based epoxy resins, bisphenol F-based epoxy resins, and phenol novolac epoxy resins. resin,
Brominated phenol novolac epoxy resin, cresol novolac epoxy resin, tetraglycidyl metaxylene diamine, tetraglycidyl-
Polyfunctional glycidyl amine compounds such as 1,3-bisaminomethylcyclohexane, tetraglycidylamino diphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, diglycidylaniline, diglycidyl orthotoluidine, 1 ,4-butanedio-
Polyfunctional glycidyl ether compounds such as 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, glycerol polyglycidyl ether, sorbitol polyglycidyl ether, phthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester , glycidyl ester compounds such as trimellitic acid polyglycidyl ester, and the like. These epoxy compounds may be used alone or in combination of two or more.

The acid anhydride and epoxy compound are used in combination with the amorphous polyester, and the amount used is 1 to 40 parts by weight of the acid anhydride per 100 parts by weight of the amorphous polyester.
Parts by weight, more preferably 1 to 30 parts by weight, also 1
The amount of the epoxy compound having two or more epoxy groups in the molecule is 1 to 50 parts by weight, more preferably 2 to 40 parts by weight. If the content of the acid anhydride or epoxy compound is lower than the above lower limit, the adhesive strength, especially the shear adhesive strength that has an important effect on press workability, will not improve much, and the effect of adding both of the above compounds will be small. Furthermore, if the content of the acid anhydride or epoxy compound is higher than the above upper limit, although the shear adhesive strength is significantly improved, the damping performance decreases, making it unsuitable as a viscoelastic composition for vibration damping materials.

In addition, in order to improve adhesive strength without reducing the vibration damping performance caused by amorphous polyester, the acid anhydride and epoxy compound blended into the amorphous polyester have a molar ratio of epoxy group/acid anhydride group. in
It is preferably 0.5 to 5, more preferably
It is 0.5-4. This optimum blending ratio varies depending on the molecular weight of the amorphous polyester, the type of terminal functional group, and the types of acid anhydride and epoxy compound used together.

In the composition of the present invention, the functional group at the end of the amorphous polyester reacts with the acid anhydride group and the epoxy group, so that the amorphous polyester is finally crosslinked, improving adhesive strength and vibration damping performance. The following characteristics are satisfied. This crosslinking reaction involves the acid anhydride used,
Depending on the combination of epoxy compounds, the reaction may proceed easily by heating after a resin composition layer is formed between the metal materials. It is also possible to use various catalysts to match the appropriate reaction rates.

For example, catalysts for the reaction between hydroxyl groups and epoxy groups include Zn(BF ₄ ) ₂ , KOH, SnCl ₄ , etc. For reactions between carboxyl groups and epoxy groups, and for reactions between acid anhydrides and epoxy groups, benzylmethylamine, Tertiary amines such as tributylamine and tris(dimethylamino)methylphenol, quaternary ammonium salts such as triethylbenzylammonium chloride and tetramethylammonium chloride, 2-methyl-
Examples include imidazole compounds such as 4-ethylimidazole and 2-methylimidazole. Further, for the reaction between a hydroxyl group and an acid anhydride group, imidazole compounds, ferric acetylacetone salts, etc. are exemplified.

Furthermore, conductivity can be imparted to the composition 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 substances used for this purpose include metals such as stainless steel, zinc, tin, copper, brass, and nickel processed into powder, flake, fiber, and wire forms, and copper plating. Examples include treated glass flakes and fibers, metal-plated glass flakes such as nickel-plated glass flakes, and conductive carbonaceous materials such as carbon black, graphite, and carbon fiber. These conductive substances can be used alone or in combination of two or more. and,
As these conductive substances, metal substances are preferable in order to exhibit good conductivity with metal materials when producing a metal composite material. If this metal substance is in powder form, its maximum particle size, and
If it is in the form of a flake, its maximum thickness is taken as its representative length (l), and if it is in the form of a fiber or wire, its maximum diameter is taken as its representative length (l).
In order to develop better conductivity, the ratio (L/T) between this representative length (L) and the total thickness (T) of the resin intermediate layer after being bonded between the metal materials is set to 0.5.
The above value is preferably 0.8 or more, more preferably 1.0 or more.

In addition, various additives such as various fillers and antioxidants can be used as necessary.

In addition, regardless of the use of additives such as the conductive solid substance described above, the use of a silane coupling agent is also effective in order to further improve the adhesive strength. The silane coupling agent is preferably one having a functional group that can react with any of the functional groups in the resin composition, ie, hydroxyl groups, carboxyl groups, acid anhydride groups, and epoxy groups. Such silane coupling agents include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyldiethoxymethoxysilane, and γ-aminopropyltriisopropoxysilane. Silane, N-β-(aminoethyl)-γ-
Aminopropyltrimethoxysilane, N-β-
(aminoethyl)-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltri(2-methoxyethoxy)silane, and other amine-based silane coupling agents having amino groups; (3,4-epoxy-cyclohexyl)
Epoxy-based silane coupling agents having epoxy groups such as ethyl-trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropyltrimethoxysilane;
-Mercaptopropyltrimethoxysilane, γ-
Examples include mercapto-based silane coupling agents having a mercapto group such as mercaptopropylmethyldiethoxysilane.

The method for producing the composite damping material using the viscoelastic composition of the present invention is not particularly limited, and may be any method such as a batch method using a cut plate or a continuous method using a coil. can be adopted. In addition, methods for forming a viscoelastic resin composition layer on a steel plate include a method in which a paint-like resin solution is applied to the steel plate, the solvent is dried, and the steel plate is bonded by heat and pressure; A method in which a viscoelastic resin composition layer is formed on a releasable base material such as release paper or polyolefin film, and the viscoelastic resin composition layer is transferred to the steel plate. Any method can be used, such as a method of bonding by heat-pressing.

[Effect]

The viscoelastic material of the present invention simultaneously satisfies the contradictory properties of vibration damping performance in the room temperature range and shear adhesive strength, which have been difficult to achieve with conventional compositions. The reason for this property is probably the relatively small amount of acid anhydride used in the amorphous polyester.
The epoxy compound is three-dimensionally crosslinked to form a crosslinked product in the resin composition, and the amorphous polyester, which has a functional group at the end and has excellent vibration damping performance, is also crosslinked at the same time, resulting in interfacial adhesion with metal materials. It also works effectively to improve vibration damping performance, achieving high adhesive strength that is difficult to achieve with a single non-crosslinked amorphous polyester resin or the commonly used multifunctional isocyanate crosslinking agents. ,
In particular, it is considered that it has become possible to improve shear adhesive strength, which has an important effect on press workability.

〔Example〕

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

The resin was prepared as a methyl ethyl ketone solution, and an acid anhydride, an epoxy compound, and various additives as necessary were added to the solution to form a paint-like composition. This paint-like composition was applied to a 0.8 mm thick cold-rolled steel plate, dried at 160°C for 3 minutes, then the two steel plates were laminated and heat-pressed at 180°C for 5 minutes to form an intermediate viscoelastic resin layer. A damping material with a diameter of 70 mm was obtained. T-peel adhesive strength is JIS K-6854
The shear adhesive strength was evaluated at a tensile speed of 5 mm/min based on JIS K-6850. Damping performance was measured using the mechanical impedance method at 500Hz.

Example 1 Loss tangent (tan
The maximum value of δ) is 1.31, and the temperature at which this maximum occurs is
At 11.1°C, 100 parts by weight of a 2:1 mixture of an amorphous polyester with a molecular weight of 15,000 to 20,000 and an amorphous polyester with a molecular weight of 15,000 to 20,000 whose maximum value of tan δ is 1.39 and a maximum temperature of 37.7°C. 5 parts by weight of pyromellitic anhydride (molecular weight: 188) and 12 parts by weight of 1,3-bis(N,N glycidylaminomethyl)cyclohexane (epoxy equivalent: 99) were blended, and a damping material was prepared by the method described above. In addition, in this formulation, the molar ratio of epoxy group/acid anhydride group is 2.3. T
Peel adhesive strength is 28Kgf/25mm, shear adhesive strength is
At 115Kgf/cm ² , the damping performance is as shown in Figure 1, the maximum value of loss coefficient ηmax = 0.85, and the temperature at which ηmax is reached.
Tp was 31°C.

Comparative Example 1 A damping material was produced in the same manner as in Example 1 using the amorphous polyester without using any acid anhydride or epoxy compound.

The T-peel adhesive strength was 7 Kgf/25 mm, the shear adhesive strength was 11 Kgf/cm ² , and the damping performance was ηmax = 1.2 and Tp = 26°C, as shown in Figure 1.

Comparative Example 2 Using the amorphous polyester of Example 1, a vibration damping material was prepared by adding 5 parts by weight of pyromellitic anhydride to 100 parts by weight of the amorphous polyester without blending an epoxy compound. T-peel adhesive strength is 8kg
f/25 mm, and shear adhesive strength was 10 Kgf/cm ² .
Moreover, the damping performance was almost the same as that of Comparative Example 1.

Comparative Example 3 Using the amorphous polyester of Example 1, 12 parts by weight of 1,3-bis(N,N glycidylaminomethyl)cyclohexane was blended with 100 parts by weight of the amorphous polyester, and the acid anhydride was A damping material was produced without using it.

The T-peel adhesive strength was 3 kgf/25 mm, the shear adhesive strength was 4 kgf/cm ² , and the vibration damping performance was almost the same as that of Comparative Example 1.

Example 2 The amorphous polyester of Example 1 was used, the acid anhydride of Example 1 was replaced with benzophenonetetracarboxylic anhydride (molecular weight 320), and 8 parts of this was added to 100 parts by weight of the amorphous polyester. Part by weight, 1,
A damping material was prepared by blending 12 parts by weight of 3-bis(N,N glycidylaminomethyl)cyclohexane (epoxy equivalent: 99). In addition, in this formulation, the molar ratio of epoxy group/acid anhydride group is 2.4.

The T-peel adhesive strength was 18 Kgf/25 mm, and the shear adhesive strength was 75 Kgf/cm ² . In addition, the damping performance is shown in Example 1.
It was almost the same as ηmax=0.8 and Tp=30°C.

Example 3 Using the amorphous polyester of Example 1, the epoxy compound of Example 1 was replaced with a bisphenol A type epoxy resin having an epoxy equivalent of 190, and this was added in an amount of 15 parts by weight per 100 parts by weight of the amorphous polyester. Department,
A damping material was prepared using 5 parts by weight of pyromellitic anhydride (molecular weight 188). In addition, in this formulation, the molar ratio of epoxy group/acid anhydride group is 1.5.

The T-peel adhesive strength was 30 kgf/25 mm, and the shear adhesive strength was 110 kgf/cm ² . Furthermore, the damping performance was almost the same as in Example 1, with ηmax=0.82 and Tp=28°C.

Example 4 To the composition of Example 3 consisting of the amorphous polyester, epoxy compound, and acid anhydride, 30 parts by weight of nickel powder classified to 200 mesh (74 μm) or less was added to 100 parts by weight of the amorphous polyester. , we created a vibration damping material.

The T-peel adhesive strength was 30 kgf/25 mm, and the shear adhesive strength was 100 kgf/cm ² . As shown in Figure 1, the damping performance was ηmax = 0.62 and Tp = 34°C.

This material has a pressure of 250Kg, a current flow of 12KA,
Spot welding was possible without any problems under the condition of 10 cycles of current application.

Comparative Example 4 The amorphous polyester of Example 1 was used, and 100 parts by weight of the amorphous polyester was mixed with an isocyanate crosslinking agent, a tolylene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethane,
A vibration damping material was obtained using 10 parts by weight of Coronate L).

The T-peel adhesive strength was 13 kgf/25 mm, and the shear adhesive strength was 25 kgf/cm ² .

〔Effect of the invention〕

The viscoelastic composition of the present invention exhibits excellent vibration damping performance when sandwiched between two metal materials, and in particular, simultaneously achieves contradictory properties of vibration damping performance at room temperature and shear adhesive strength. Since a satisfactory intermediate layer is formed, a composite damping material that can be used in a wide temperature range can be provided, and is extremely useful as a viscoelastic composition for a damping material.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the temperature dependence of the loss coefficient of a damping material.

Claims (1)

[Claims] 1. The maximum value of loss tangent (tan δ) based on glass transition is 0.5 or more, and the temperature at which this maximum occurs is -40°C.
For 100 parts by weight of amorphous polyester between ~120°C, 1 to 40 parts by weight of acid anhydride, 2 parts per molecule.
1 epoxy compound having 1 or more epoxy groups
A viscoelastic composition for a composite vibration damping material containing ~50 parts by weight. 2. The composite mold according to claim 1, wherein the acid anhydride and epoxy compound blended into the amorphous polyester have an epoxy group/acid anhydride group molar ratio of 0.5 to 5. Viscoelastic composition for vibration materials. 3. Composite vibration damping according to claims 1 or 2, characterized in that at least one component of the acid anhydride is a polyfunctional compound having two or more acid anhydride groups in one molecule. Viscoelastic composition for materials.