JPH04312845A - Vibration-damping metal plate - Google Patents

Abstract

PURPOSE:To obtain a vibration-damping metal plate. CONSTITUTION:A vibration-damping metal plate consists of a resin composition, present in a thickness ranging from 30 to 150mum, which contains 25 to 250 pts.wt. of epoxy resin having two or more epoxy groups in a single molecule and 5 to 50 pts.wt. of curing agent blended with 100 pts.wt. of a copolymer, of vinyl esters and unsaturated carboxylic acids, at a temperature, indicating the maximum value of a loss tangent (tandelta) based on a glass transition point, staying between -70 to 120 deg.C. Thus the vibration-damping metal plate thus obtained is best suited for use at a normal or a high temperature.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a vibration-damping metal plate (hereinafter referred to as vibration-damping material) which is used as a damping material for noise sources by interposing a resin composition with excellent vibration-damping properties as an intermediate layer. metal plate). More specifically, the present invention relates to a vibration-damping metal plate that constitutes a component of a building or a machine, or a part thereof, and has a high vibration damping ability that reduces noise by reducing vibrations thereof.

0002

[Background Art] In recent years, with the development of transportation systems and the proximity of residences to factories and workplaces, countermeasures against noise generated by various transportation systems and machinery have become an important issue from the perspective of environmental conservation in local communities. It has become. In particular, vibration-damping metal plates are being considered or adopted for automobile oil pans, dash panels, outer panels of electric washing machines, hopper chutes, general-purpose engine covers, and vibration reduction members for metal processing machines.

Polyurethane has conventionally been used as the intermediate layer resin of this vibration-damping metal plate (Japanese Patent Application Laid-open No. 19277-1989).
, vinyl urethane resin (JP-A-50-39737), polyester resin (JP-A-50-143880), polyamide resin (JP-A-51-79146), polyisobutylene (JP-A-54-43251)
(Japanese Unexamined Patent Publication No. 1982-8), ethylene/α-olefin
4655), EVA (Japanese Unexamined Patent Publication No. 57-34949)
Publication No.), cross-linked olefin (JP-A-59-152847)
(Japanese Patent Application Laid-open No. 60-38), polyvinyl acetal
Publication No. 149) etc. are being considered, and asphalt,
Synthetic rubber, acrylic adhesives, and the like are also known to have vibration damping properties.

0004

[Problem to be solved by the invention] Among these resins,
Resins that are flexible at room temperature, such as acrylic adhesives, polyisobutylene, and EVA, have relatively high vibration damping properties at temperatures around room temperature, but their adhesive strength is low due to the low cohesive force of the resin at room temperature. The damping metal plate used cannot withstand forming processes such as press working, and does not have adhesive heat resistance to the extent that it can withstand a baking process.

[0005] Furthermore, polyolefin resins modified or modified by copolymerization or blending, such as ethylene/α-olefin resins, have a molecular weight of 50 to 10% compared to the former.
It has relatively excellent vibration damping properties in the high temperature range of 0℃, has high resin cohesion at room temperature, and is compatible with molding processing.
It is said that a vibration damping metal plate using the resin is suitable for vibration damping metal plates used at high temperatures such as oil pans of automobiles.

However, even if their uses are limited, they cannot be said to reach sufficiently satisfactory levels in vibration damping properties and adhesive strength, and since they are thermoplastic resins, they cannot be used at high temperatures during the baking process. There is also no adhesive heat resistance at the bottom. Therefore, vibration-damping metals, such as parts around the body of automobiles, must have high vibration-damping properties in a temperature range ranging from room temperature to high temperatures, and must also have strong adhesive strength that can be used in molding processes, and adhesive heat resistance at high temperatures. Not much is known about the resin suitable for boards.

[0007] The present invention solves the above problems and can be used as an intermediate layer at room temperature (0~40°C) and high temperature (60°C).
-120℃) or a wide temperature range (0 to 120℃), and uses a resin composition that has strong adhesive strength that follows molding processing and adhesive heat resistance under the high temperature of the baking painting process. The object of the present invention is to provide a vibration-damping metal plate.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have made extensive studies and have developed a method using a copolymer of specific vinyl esters and unsaturated carboxylic acids, an epoxy resin, and a curing agent. The present inventors have discovered that a vibration-damping metal plate having extremely excellent properties can be obtained by using a resin composition, and have completed the present invention.

That is, the present invention provides a copolymer of vinyl esters and unsaturated carboxylic acids, an epoxy resin, and a cured resin having a maximum loss tangent (tan δ) between -70 and 120°C between metal plates. This is a vibration-damping metal plate in which a resin composition consisting of an agent is interposed with a thickness of 30 to 150 μm.

0010

[Operation] The structure and operation of the present invention will be explained. The resin composition used in the present invention is a material for an intermediate layer for a vibration-damping metal plate, which is composed of a plurality of metal layers and an intermediate layer that joins them together, and is composed of vinyl esters and unsaturated carboxylic acids. It consists of a copolymer, a predetermined amount of epoxy resin, and a curing agent. This resin composition has a tan δ maximum temperature of −7
It is a copolymer of vinyl esters and unsaturated carboxylic acids at a temperature between 0 and 120°C.

[0011] The vibration-damping metal plate is used for things that require vibration-damping properties in the room temperature range, such as automobile dash panels, floors, outer panels of electric washing machines, hopper chutes, general-purpose engine covers, and automobile oil. Damping properties are mainly required in the high temperature range of 80 to 100°C for bread, and in order to exhibit damping properties in any of the above temperature ranges, the maximum temperature of tan δ must be between -70 to 120°C. There needs to be something in between. In order to exhibit vibration damping properties at room temperature, tanδ
It is preferable that the maximum temperature of is between -50 and 40°C. In addition, in order to exhibit vibration damping properties in a high temperature range, tan
It is desirable that the maximum temperature of δ is between 20 and 80°C.

The copolymer of vinyl esters and unsaturated carboxylic acids used in the present invention can be synthesized by radical copolymerization of vinyl esters and unsaturated carboxylic acids.

Vinyl esters which are one component of the copolymer include vinyl carboxylates such as vinyl acetate, vinyl propionate or vinyl butyrate, methyl acrylate,
Acrylic esters such as ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate or 2-ethylhexyl methacrylate; and the like. Two or more of these vinyl esters can also be used in combination.

On the other hand, examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid or fumaric acid, and anhydrides thereof. Alternatively, a mixture thereof may be used.

[0015] As a polymerization initiator for copolymerization,
Any conventional polymerization initiator such as azobisisobutyronitrile or benzoyl peroxide is suitably used.

Examples of the solvent used in the polymerization include methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, isopropyl acetate, and benzene. From the viewpoint of controlling the polymerization temperature and the degree of polymerization of the resulting copolymer, these solvents may be used alone or as a mixed solvent as appropriate.

The proportion of the unsaturated carboxylic acid component in the copolymer produced according to the invention is preferably in the range of 1 to 6 mol %. If it exceeds this range, the vibration damping properties of the copolymer will deteriorate, which is not preferable.

The vinyl esters, unsaturated carboxylic acids, and polymerization initiators are all commercially available, or can be manufactured and used by known methods.

Copolymerization of vinyl esters and unsaturated carboxylic acids can be carried out under solution polymerization conditions using, for example, methyl alcohol or acetone. The copolymer obtained by removing the solvent has a number average molecular weight of 5.
It has a molecular weight of 1,000 to 100,000 and is usually soluble in solvents such as methyl alcohol and acetone.

[0020] In addition, epoxy resin contains 2 in one molecule.
Examples include bisphenol A-based epoxy resins, bisphenol F-based epoxy resins, phenol novolak epoxy resins, cresol novolak epoxy resins, and various rubber-modified epoxy resins. These epoxy resins may be used alone or in combination of two or more.

The curing agent is a curing agent commonly used in the curing reaction of epoxy resins, and includes chain aliphatic polyamines, cycloaliphatic polyamines, aliphatic/aromatic polyamines, aromatic polyamines, aromatic diamine eutectic mixtures, etc. Primary amines, modified polyamines consisting of various adducts, secondary amines,
Examples include tertiary amines, polyamide resins and adducts thereof, various imidazoles, and various latent curing agents. These curing agents may be used alone or in combination of two or more.

In the resin composition used in the present invention, the epoxy group in the epoxy resin reacts with the curing agent and the carboxyl group in the copolymer consisting of vinyl esters and unsaturated carboxylic acids, so that the final The copolymer is crosslinked to satisfy various properties such as vibration damping properties, adhesive strength, and adhesive heat resistance at high temperatures. In this crosslinking reaction, the types and amounts of the epoxy resin and curing agent used are appropriately combined in order to achieve an appropriate reaction rate in accordance with the actual operating conditions of the production line. The amount of the epoxy resin to satisfy various properties such as vibration damping properties and adhesive strength is preferably 25 to 100 parts by weight and the curing agent is 5 to 50 parts by weight.

Furthermore, considering the manufacturing conditions of the vibration-damping metal plate, the resin composition comprising the copolymer, epoxy resin, and curing agent of the present invention is compatible with general-purpose solvents such as toluene, MEK (methyl ethyl ketone), and ethyl acetate. Preferably, it is dissolved in a solvent, which makes it easier to coat the metal plate, prevents gas from being entrained in the laminated part, and contains conductive fillers, additives, etc. to provide spot weldability during processing. Advantages such as ease of mixing or adding occur.

[0024] Furthermore, an antioxidant is added to improve the heat resistance of the resin composition. The amount of this antioxidant added is usually 1 to 4% by weight based on the resin composition. The antioxidant can also be added directly to the polymerization reaction solution after completion of polymerization. Further, the antioxidant is appropriately added using a suitable mixing device such as a kneader. As this antioxidant, high molecular weight hindered phenol [(Irganox 1076) manufactured by Nippon Ciba Geigy Co., Ltd.] and the like are used.

Furthermore, the resin composition used in the present invention includes:
Various conductive fillers such as carbon black, graphite, and metal powder can be blended to impart conductivity to the damping metal plate for the purpose of improving weldability. The properties of the resin composition thus obtained include good vibration damping properties, adhesive strength, adhesive heat resistance, and coatability.

The above-mentioned resin composition is interposed between metal plates to form a damping metal plate. The types of these metal plates are not particularly limited. Furthermore, these metal plates may be of the same type or of different types. As such a metal plate, for example, a steel plate (including a surface-treated steel plate, a stainless steel plate, etc.), an aluminum plate, a copper plate, and a surface-treated plate thereof can be suitably used depending on the application, environment, and the like.

[0027] The thickness of the intermediate resin layer is 30 to 150 μm.
If it is less than 30 μm, it may be affected by the surface condition or warpage of the metal plates to be laminated, and sufficient adhesive strength may not be obtained. Also 150μm
If it exceeds this, press formability will deteriorate significantly.

[0028] In the resin composition used in the present invention, the copolymer, epoxy resin, and hardening agent are stored separately, and the two are mixed during the production of vibration-damping metal plates.
When an aromatic polyamine or the like having low reactivity is used, the resin composition exists fairly stably at room temperature, so it can be supplied as a one-component type. One-component type or two-component type is selected depending on the resin composition and actual operating conditions of the production line, but in the case of two-component type, it is necessary to properly mix the two components and supply it to the production line. Therefore, the one-component type is preferable from an operational standpoint.

[0029] In order to produce a damping metal plate using the resin composition, 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 resin composition on a metal plate include a method of applying a paint-like resin solution to the metal plate, drying the solvent, and bonding the metal plate by heat-pressing, or a method using release paper, Any method can be employed, such as a method of forming a resin composition layer on a release film such as polyolefin, transferring the resin composition to a metal plate, and bonding the metal plate by heat and pressure bonding.

[0030]

[Examples] Examples of the present invention will be described below, but the present invention is not limited thereto. The methods for measuring the characteristics of the copolymer of vinyl esters and unsaturated carboxylic acids used in the examples, the laminating/adhering method, and the method for measuring the characteristics of the vibration-damping metal plate are as follows.

■Number average molecular weight of the copolymer (bar Mn) The copolymer was dissolved in tetrahydrofuran and subjected to size exclusion chromatography (manufactured by Nippon Waters Limited).
Mn was determined using polystyrene conversion (GPC).

(2) Glass transition temperature (Tg) of copolymer Measured using a heat flux differential scanning calorimeter manufactured by Rigaku Corporation at a heating rate of 10° C./min.

■Metal Plate Used A cold-rolled steel plate with a thickness of 0.8 mm was degreased and used.

■ Lamination/adhesion method A predetermined amount of epoxy resin and a curing agent dissolved in propylene glycol methyl ether are added to a copolymer solution synthesized in an acetone solvent, and MEK is added as necessary to reduce the solid content to approximately 30. % solution was applied to one side of a steel plate using a roll coater to give a resin film thickness of 100 μm, and after application, it was dried and the solvent was removed in a drier (140° C. for 3 minutes). After that, another steel plate was placed on the resin coated surface, and it was molded using a compression molding machine (240℃ x 2 minutes x surface pressure 20kgf/cm2).
) was heated and bonded and evaluated.

① Adhesive Strength The steel plates laminated and bonded above were cut to a width of 35 mm, and the shear tensile strength was measured at room temperature according to the JIS method (K6850). Similarly, it was cut to a width of 25 mm, and the T-peel strength was measured at room temperature according to the JIS method (K6854).

■Vibration damping property A rectangular sample (20 mm width x 200 mm length) was prepared from the laminated and bonded steel plates described above, and was tested at B&K (Briuel
and Kjeaer Ltd. ) using a complex elastic modulus measuring device made by the company, the measurement frequency was 250 by the resonance method.
Vibration damping tests were conducted at Hz.

■ Formability The steel plates laminated and bonded above are 20 mm wide x 200 mm.
The pieces were cut into long pieces, and the ends were bent at a right angle of 10 mm. Those with peeling at the bent portions were marked with an x, and those with no change were marked with a mark of ○. Similarly, the bent parts were left in a constant temperature bath at 150℃ for 8 hours, and the bent parts peeled off.
Items with no change are marked with a circle.

The acrylic ester resin, epoxy resin, and curing agent shown in Tables 1, 2, and 3 were prepared, and a resin composition prepared by mixing each of them at the mixing ratio shown in the table was interposed, and the above-mentioned (1) lamination/ A damping steel plate was manufactured using the gluing method. The properties of the damping steel plate obtained through this process (adhesive strength,
The temperature dependence of moldability and vibration damping properties) were measured, and the measurement results are shown in Tables 1, 2, and 3.

According to the measurement results shown in Tables 1, 2, and 3, the bending process of Example 9 in Table 3 was
In a peel test in which the resin composition was left in a constant temperature bath at 50°C for 8 hours, no defects were observed except for peeling. A steel plate was obtained.

[0040] In the table, GY260: Bisphenol A
Type epoxy resin (manufactured by Nippon Ciba Geigy, epoxy equivalent: 180-200), YL6066: Rubber-modified epoxy resin (manufactured by Yuka Shell Epoxy, epoxy equivalent: 35)
2), EP-4005: Bisphenol A alkylene oxide adduct (manufactured by Asahi Denka Kogyo Co., Ltd., epoxy equivalent: 50
0 to 575), YR-450: Flexible epoxy resin (
MY-24, AH-162, and AH-209: Amicure (manufactured by Ajinomoto Co., Ltd.) were used in this example.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

Atmospheric temperature and loss coefficient (tan δ) of a vibration damping steel plate prototyped using a resin composition consisting of n-butyl acrylate and acrylic acid as an acrylic ester resin
Figure 1 shows the results of examining the relationship.

[0045] As is clear from Fig. 1, the vibration damping steel plate prototyped using the resin composition described above was
The loss coefficient in the area is 0.1 or more, and the damping performance is high.

Similarly, FIG. 2 shows an example of the results of examining the relationship between the ambient temperature and the loss coefficient (tan δ) of vibration damping steel plates prototyped using acrylic acid ester resins with different types of monomers.

As is clear from FIG. 2, by changing the type of monomer, the maximum temperature, maximum value, and temperature dependence of the loss coefficient can be changed in a preferable direction.

[0048] Therefore, it can be seen that the vibration-damping metal plate interposed with the resin composition used in the present invention is suitable for use at room temperature or constant temperature depending on the usage conditions.

[0049]

Effects of the Invention Since the present invention is constructed as described above, the epoxy resin and curing agent used together with the copolymer of vinyl esters and unsaturated carboxylic acids are three-dimensionally crosslinked to form a resin composition. In addition to forming a crosslinked product in the object, the carboxyl groups in the copolymer are also crosslinked at the same time, which effectively improves the adhesion at the interface with metal materials, improving press workability without reducing vibration damping properties. This is thought to be due to the high adhesive strength (shear tensile strength) that has a large effect on the adhesive properties and the adhesive heat resistance under the high temperatures of the baking painting process.
A vibration-damping metal plate having favorable vibration-damping properties, adhesive strength, and adhesive heat resistance can be obtained, and is extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is an actual measurement graph showing an example of the temperature dependence of the loss coefficient of the damping metal plate of the present invention.

FIG. 2 is an actual measurement graph showing an example of the temperature dependence of the loss coefficient of the damping metal plate of the present invention.

Claims (1)

[Claims] Claim 1: As an essential component, the temperature at which the loss tangent (tan δ) reaches a maximum due to glass transition is -70 to -70.
For 100 parts by weight of a copolymer of vinyl esters and unsaturated carboxylic acids between 120°C and 25 to 25 parts by weight of an epoxy resin having two or more epoxy groups in one molecule.
A resin composition for an intermediate layer containing 100 parts by weight and 5 to 50 parts by weight of a curing agent was placed between a plurality of metal plates at 30 parts by weight.
A vibration-damping metal plate characterized in that the vibration-damping metal plate is interposed with a thickness in the range of 150 μm.